National Library of Energy BETA

Sample records for negligible negligible negligible

  1. Negligible sample heating from synchrotron infrared beam

    SciTech Connect (OSTI)

    Martin, Michael C.; Tsvetkova, Nelly M.; Crowe, John H.; McKinney, Wayne R.

    2000-08-30

    The use of synchrotron sources for infrared (IR) spectromicroscopy provides greatly increased brightness enabling high-quality IR measurements at diffraction-limited spatial resolutions. This permits synchrotron-based IR spectromicroscopy to be applied to biological applications at spatial resolutions of the order of the size of a single mammalian cell. The question then arises, ''Does the intense synchrotron beam harm biological samples?'' Mid-IR photons are too low in energy to break bonds directly, however they could cause damage to biological molecules due to heating. In this work, we present measurements showing negligible sample heating effects from a diffraction-limited synchrotron IR source. The sample used is fully hydrated lipid bilayers composed of dipalmitoylphosphatidylcholine(DPPC), which undergoes a phase transition from a gel into a liquid-crystalline state at about 315 K during heating. Several IR-active vibrational modes clearly shift in frequency when the sample passes through the phase transition. We calibrate and then use these shifting vibrational modes as an in situ temperature sensor.

  2. Application of Negligible Creep Criteria to Candidate Materials for HTGR Pressure Vessels

    SciTech Connect (OSTI)

    Jetter, Robert I; Sham, Sam; Swindeman, Robert W

    2011-01-01

    Two of the proposed High Temperature Gas Reactors (HTGRs) under consideration for a demonstration plant have the design object of avoiding creep effects in the reactor pressure vessel (RPV) during normal operation. This work addresses the criteria for negligible creep in Subsection NH, Division 1 of the ASME B&PV (Boiler and Pressure Vessel) Code, Section III, other international design codes and some currently suggested criteria modifications and their impact on permissible operating temperatures for various reactor pressure vessel materials. The goal of negligible creep could have different interpretations depending upon what failure modes are considered and associated criteria for avoiding the effects of creep. It is shown that for the materials of this study, consideration of localized damage due to cycling of peak stresses results in a lower temperature for negligible creep than consideration of the temperature at which the allowable stress is governed by creep properties. In assessing the effect of localized cyclic stresses it is also shown that consideration of cyclic softening is an important effect that results in a higher estimated temperature for the onset of significant creep effects than would be the case if the material were cyclically hardening. There are other considerations for the selection of vessel material besides avoiding creep effects. Of interest for this review are (1) the material s allowable stress level and impact on wall thickness (the goal being to minimize required wall thickness) and (2) ASME Code approval (inclusion as a permitted material in the relevant Section and Subsection of interest) to expedite regulatory review and approval. The application of negligible creep criteria to two of the candidate materials, SA533 and Mod 9Cr-1Mo (also referred to as Grade 91), and to a potential alternate, normalized and tempered 2 Cr-1Mo, is illustrated and the relative advantages and disadvantages of the materials are discussed.

  3. Negligible Magnetism in Excellent Structural Quality Cr[subscript x]Ti[subscript 1-x]O[subscript 2] Anatase: Contrast with High-T[subscript C] Ferromagnetism in Structurally Defective Cr[subscript x]Ti[subscript 1-x]O[subscript 2

    SciTech Connect (OSTI)

    Kaspar, T.C.; Heald, S.M.; Wang, C.M.; Bryan, J.D.; Droubay, T.; Shutthanandan, V.; Thevuthasan, S.; McCready, D.E.; Kellock, A.J.; Gamelin, D.R.; Chambers, S.A.

    2010-07-19

    We reexamine the mechanism of ferromagnetism in doped TiO{sub 2} anatase, using epitaxial Cr:TiO{sub 2} with excellent structural quality as a model system. In contrast to highly oriented but defective Cr:TiO{sub 2} ({approx}0.5{micro}{sub B}/Cr), these structurally superior single crystal films exhibit negligible ferromagnetism. Similar results were obtained for Co:TiO{sub 2}. We show for the first time that charge-compensating oxygen vacancies alone, as predicted by F-center mediated exchange, are not sufficient to activate ferromagnetism. Instead, the onset of ferromagnetism correlates with the presence of structural defects.

  4. Down-regulation of gibberellic acid in poplar has negligible effects on host-plant suitability and insect pest response

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Buhl, Christine; Strauss, Steven H.; Lindroth, Richard L.

    2015-01-06

    Abstract Endogenous levels and signaling of gibberellin plant hormones such as gibberellic acid (GA) have been genetically down-regulated to create semi-dwarf varieties of poplar. The potential benefits of semi-dwarf stature include reduced risk of wind damage, improved stress tolerance, and improved wood quality. Despite these benefits, modification of growth traits may have consequences for non-target traits that confer defense against insect herbivores. According to the growth-differentiation balance hypothesis, reductions in growth may shift allocation of carbon from growth to chemical resistance traits, thereby altering plant defense. To date, host-plant suitability and pest response have not been comprehensively evaluated in GAmore » down-regulated plants. We quantified chemical resistance and nitrogen (an index of protein) in GA down-regulated and wild-type poplar (Populus alba × P. tremula) genotypes. We also evaluated performance of both generalist (Lymantria dispar) and specialist (Chrysomela scripta) insect pests reared on these genotypes. Our evaluation of resistance traits in four GA down-regulated genotypes revealed increased phenolic glycosides in one modified genotype and reduced lignin in two modified genotypes relative to the non-transgenic wild type. Nitrogen levels did not vary significantly among the experimental genotypes. Generalists reared on the four GA down-regulated genotypes exhibited reduced performance on only one modified genotype relative to the wild type. Specialists, however, performed similarly across all genotypes. Results from this study indicate that although some non-target traits varied among GA down-regulated genotypes, the differences in poplar pest susceptibility were modest and highly genotype-specific.« less

  5. Down-regulation of gibberellic acid in poplar has negligible effects on host-plant suitability and insect pest response

    SciTech Connect (OSTI)

    Buhl, Christine; Strauss, Steven H.; Lindroth, Richard L.

    2015-01-06

    Abstract Endogenous levels and signaling of gibberellin plant hormones such as gibberellic acid (GA) have been genetically down-regulated to create semi-dwarf varieties of poplar. The potential benefits of semi-dwarf stature include reduced risk of wind damage, improved stress tolerance, and improved wood quality. Despite these benefits, modification of growth traits may have consequences for non-target traits that confer defense against insect herbivores. According to the growth-differentiation balance hypothesis, reductions in growth may shift allocation of carbon from growth to chemical resistance traits, thereby altering plant defense. To date, host-plant suitability and pest response have not been comprehensively evaluated in GA down-regulated plants. We quantified chemical resistance and nitrogen (an index of protein) in GA down-regulated and wild-type poplar (Populus alba P. tremula) genotypes. We also evaluated performance of both generalist (Lymantria dispar) and specialist (Chrysomela scripta) insect pests reared on these genotypes. Our evaluation of resistance traits in four GA down-regulated genotypes revealed increased phenolic glycosides in one modified genotype and reduced lignin in two modified genotypes relative to the non-transgenic wild type. Nitrogen levels did not vary significantly among the experimental genotypes. Generalists reared on the four GA down-regulated genotypes exhibited reduced performance on only one modified genotype relative to the wild type. Specialists, however, performed similarly across all genotypes. Results from this study indicate that although some non-target traits varied among GA down-regulated genotypes, the differences in poplar pest susceptibility were modest and highly genotype-specific.

  6. Fuel Cell Handbook (Seventh Edition)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... having equal number of mols of gas reactants and products, has a negligible change in entropy and thus a negligible heat effect if carried out reversibly at constant temperature. ...

  7. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    reactor systems is negligible because the neutron capture cross-section is low for fast fission neutrons. At the INL, scientists have previously transported fission products...

  8. DOE/EIA-0358

    U.S. Energy Information Administration (EIA) Indexed Site

    of nonpurchased byproduct or waste stream fuels and a negligible amount of nontraditional energy sources such as solar, hydropower, etc. When this figure is adjusted to account for...

  9. U.S. DEPARTMENT OF ENERGY * SAVANNAH RIVER ...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    E-mail: dale.haas@srnl.doe.gov Uses naturally occurring microorganisms Negligible toxicity Promotes rapid hydrocarbon breakdown Provides for oil recovery from existing waste...

  10. Research Highlights Sorted by Title

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... Frost Flowers Have Negligible Influence on Cloud Longwave Warming ARM ASR Xu, L., Russell, L. M. Are Increases in Thunderstorm Activity in Southeast China Related to Air Pollution? ...

  11. Controlled Rapid Pressurization Using Liquid Propellants for EGS Well Stimulation

    Broader source: Energy.gov [DOE]

    Project objective: Investigate the use of non-toxicŽ or negligible environmental impact liquid propellants for the stimulation of geothermal fields.

  12. SPEC CPI Demonstration

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Example of Region with High Concentration (3 cm -3 ) of Small Particles that Cause Effects of Shattering to be Negligible Example of Region with Low Concentration (0.2 cm -3 )...

  13. Depolarization due to beam-beam interaction in electron-positron...

    Office of Scientific and Technical Information (OSTI)

    in the Stanford Linear Collider (SLC) and a possible future TeV linear collider (TLC). The effects are found to be negligibly small for SLC and not very large for TLC. 7...

  14. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... the velocity of Fe-rich liquids increases upon compression and decreases with increasing sulfur content, whereas temperature has negligible effect on the velocity of Fe-S liquids. ...

  15. Directory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    order Object Created Object Last Modified Assessment of Negligible Creep Off-Normal Welding and Heat Treatment of GR91 Steel for Nuclear Reactor Pressure Vessel Application.pdf...

  16. Free Boundary, High Beta Equilibrium in a Large Aspect Ratio...

    Office of Scientific and Technical Information (OSTI)

    ... a, will be non-negligible. The higher n Fourier components of the vacuum field decay ... The higher rz Fourier components of the vacuum field decay rapidly away from the external ...

  17. MiniBooNE E. D. Zimmerman

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    SciBooNE Detector TargetHorn SciBooNE constraint reduces error at MiniBooNE * Flux errors become 1-2% level: negligible for this analysis * Cross-section errors reduced, but...

  18. untitled

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... Likewise, the facility would not be a major source of air pollution as defined in Chapter 62-210, Florida Administrative Code and would result in only a negligible impact on air ...

  19. Ultrashort pulse laser machining of metals and alloys

    DOE Patents [OSTI]

    Perry, Michael D.; Stuart, Brent C.

    2003-09-16

    The invention consists of a method for high precision machining (cutting, drilling, sculpting) of metals and alloys. By using pulses of a duration in the range of 10 femtoseconds to 100 picoseconds, extremely precise machining can be achieved with essentially no heat or shock affected zone. Because the pulses are so short, there is negligible thermal conduction beyond the region removed resulting in negligible thermal stress or shock to the material beyond approximately 0.1-1 micron (dependent upon the particular material) from the laser machined surface. Due to the short duration, the high intensity (>10.sup.12 W/cm.sup.2) associated with the interaction converts the material directly from the solid-state into an ionized plasma. Hydrodynamic expansion of the plasma eliminates the need for any ancillary techniques to remove material and produces extremely high quality machined surfaces with negligible redeposition either within the kerf or on the surface. Since there is negligible heating beyond the depth of material removed, the composition of the remaining material is unaffected by the laser machining process. This enables high precision machining of alloys and even pure metals with no change in grain structure.

  20. TMX-upgrade. X-ray diagnostic: low-energy temperature determination

    SciTech Connect (OSTI)

    Jacoby, B.A.

    1981-05-01

    In order to properly design the x-ray filter set, a reasonable computational model of the plasma emission had to be developed. The radiation continuum computed consisted of two components: bremsstrahlung and recombination radiation. The contribution of line radiation from low Z impurities was estimated to be negligible for x-ray energies above 1 keV.

  1. Cycling firing method for bypass operation of bridge converters

    DOE Patents [OSTI]

    Zabar, Zivan (99-72 66th Rd., Apt. 9N, Forest Hills, NY 11375)

    1982-01-01

    The bridge converter comprises a number of switching elements and an electronic logic system which regulated the electric power levels by controlling the firing, i.e., the initiation of the conduction period of the switching elements. Cyclic firing of said elements allows the direct current to bypass the alternating current system with high power factor and negligible losses.

  2. Rotary pneumatic valve

    DOE Patents [OSTI]

    Hardee, Harry C.

    1991-01-01

    A rotary pneumatic valve which is thrust balanced and the pneumatic pressure developed produces only radial loads on the valve cylinder producing negligible resistance and thus minimal torque on the bearings of the valve. The valve is multiplexed such that at least two complete switching cycles occur for each revolution of the cylinder spindle.

  3. SU-E-T-277: Raystation Electron Monte Carlo Commissioning and Clinical Implementation

    SciTech Connect (OSTI)

    Allen, C; Sansourekidou, P; Pavord, D

    2014-06-01

    Purpose: To evaluate the Raystation v4.0 Electron Monte Carlo algorithm for an Elekta Infinity linear accelerator and commission for clinical use. Methods: A total of 199 tests were performed (75 Export and Documentation, 20 PDD, 30 Profiles, 4 Obliquity, 10 Inhomogeneity, 55 MU Accuracy, and 5 Grid and Particle History). Export and documentation tests were performed with respect to MOSAIQ (Elekta AB) and RadCalc (Lifeline Software Inc). Mechanical jaw parameters and cutout magnifications were verified. PDD and profiles for open cones and cutouts were extracted and compared with water tank measurements. Obliquity and inhomogeneity for bone and air calculations were compared to film dosimetry. MU calculations for open cones and cutouts were performed and compared to both RadCalc and simple hand calculations. Grid size and particle histories were evaluated per energy for statistical uncertainty performance. Acceptability was categorized as follows: performs as expected, negligible impact on workflow, marginal impact, critical impact or safety concern, and catastrophic impact of safety concern. Results: Overall results are: 88.8% perform as expected, 10.2% negligible, 2.0% marginal, 0% critical and 0% catastrophic. Results per test category are as follows: Export and Documentation: 100% perform as expected, PDD: 100% perform as expected, Profiles: 66.7% perform as expected, 33.3% negligible, Obliquity: 100% marginal, Inhomogeneity 50% perform as expected, 50% negligible, MU Accuracy: 100% perform as expected, Grid and particle histories: 100% negligible. To achieve distributions with satisfactory smoothness level, 5,000,000 particle histories were used. Calculation time was approximately 1 hour. Conclusion: Raystation electron Monte Carlo is acceptable for clinical use. All of the issues encountered have acceptable workarounds. Known issues were reported to Raysearch and will be resolved in upcoming releases.

  4. Retrofit device to improve vapor compression cooling system performance by dynamic blower speed modulation

    DOE Patents [OSTI]

    Roth, Robert Paul; Hahn, David C.; Scaringe, Robert P.

    2015-12-08

    A device and method are provided to improve performance of a vapor compression system using a retrofittable control board to start up the vapor compression system with the evaporator blower initially set to a high speed. A baseline evaporator operating temperature with the evaporator blower operating at the high speed is recorded, and then the device detects if a predetermined acceptable change in evaporator temperature has occurred. The evaporator blower speed is reduced from the initially set high speed as long as there is only a negligible change in the measured evaporator temperature and therefore a negligible difference in the compressor's power consumption so as to obtain a net increase in the Coefficient of Performance.

  5. Shell structure in the density profiles for noninteracting fermions in anisotropic harmonic confinement

    SciTech Connect (OSTI)

    Vignolo, Patrizia; Minguzzi, Anna

    2003-05-01

    We develop a Green's function method to evaluate the exact equilibrium particle-density profiles of noninteracting Fermi gases in external harmonic confinement in any spatial dimension and for arbitrary trap anisotropy. While in a spherically symmetric configuration the shell effects are negligible in the case of a large number of particles, we find that for very anisotropic traps the quantum effects due to single-level occupancy and the deviations from the Thomas-Fermi approximation are also visible for mesoscopic clouds.

  6. Relaying an optical wavefront

    DOE Patents [OSTI]

    Sweatt, William C. (Albuquerque, NM); Vawter, G. Allen (Corrales, NM)

    2007-03-06

    A wavefront rely devices samples an incoming optical wavefront at different locations, optically relays the samples while maintaining the relative position of the samples and the relative phase between the samples. The wavefront is reconstructed due to interference of the samples. Devices can be designed for many different wavelengths, including for example the ultraviolet, visible, infrared and even longer wavelengths such as millimeter waves. In one application, the device function as a telescope but with negligible length.

  7. Alignment of Iron Nanoparticles in a Magnetic Field Due to Shape Anisotropy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Radhakrishnan, Balasubramaniam; Nicholson, Don M; Eisenbach, Markus; Ludtka, Gerard Michael; Rios, Orlando; Parish, Chad M

    2015-07-09

    During high magnetic field processing there is evidence for alignment of non-spherical metallic particles above the Curie temperature in alloys with negligible magneto-crystalline anisotropy. The main driving force for alignment is the magnetic shape anisotropy. Current understanding of the phenomenon is not adequate to quantify the effect of particle size, aspect ratio, temperature and the magnetic field on particle alignment. We demonstrate a Monte Carlo approach coupled with size scaling to show the conditions under which alignment is possible.

  8. Self-pumping impurity control

    DOE Patents [OSTI]

    Brooks, Jeffrey N. (Darien, IL); Mattas, Richard F. (Downers Grove, IL)

    1991-01-01

    Apparatus for removing the helium ash from a fusion reactor having a D-T plasma comprises a helium trapping site within the reactor plasma confinement device, said trapping site being formed of a trapping material having negligible helium solubility and relatively high hydrogen solubility; and means for depositing said trapping material on said site at a rate sufficient to prevent saturation of helium trapping.

  9. Nonproliferation, Nuclear Security, and the Insider Threat

    SciTech Connect (OSTI)

    Balatsky, Galya I.; Duggan, Ruth

    2012-07-12

    Insider threat concept is evolving and getting more attention: (1) Domestically, internationally and in foreign countries, (2) At the government, academia, and industry levels, and (3) Public awareness and concerns are also growing. Negligence can be an insider's action. Technology advancements provide more opportunities, new tools for the insider. Our understanding of the insider is shaped by our cultural, social and ethnic perceptions and traditions. They also can limit our recognition of the issues and response actions.

  10. siemens-postcap | netl.doe.gov

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Slipstream Development and Testing of Siemens POSTCAP Capture and Separation Technology Project No.: DE-FE0003714 Siemens Energy, Inc. will design, install, and operate a pilot plant for treating a 2.5 MW equivalent slipstream at the TECO Energy Big Bend Station to demonstrate POSTCAP technology for post-combustion CO2 gas capture. POSTCAP based technology utilizes an amino acid salt (AAS) that can operate in a conventional scrubber system similar to that for MEA, but with negligible solvent

  11. FRAP-T5 predictions during reactor shutdown events. [PWR; BWR

    SciTech Connect (OSTI)

    Peeler, G.B.; Laats, E.T.

    1980-01-01

    The Transient Fuel Rod Analysis Program, FRAP-T5, was recently assessed by EG and G Idaho, Inc. As part of this assessment, the measured and FRAP-T5 predicted fuel centerline temperature response during reactor shutdown events were compared. For these events either forced convection or nucleate boiling boundary conditions existed, resulting in a negligible effect on fuel behavior from cladding temperature and deformation uncertainties. This allowed the assessment of internal heat transfer to be emphasized.

  12. Microsoft PowerPoint - Johnson - How EM Does Business (FINAL)

    Energy Savers [EERE]

    How EM Does Business Thomas Johnson, Jr. Associate Deputy Assistant Secretary for Acquisition and Project Management Environmental Management Site-Specific Advisory Board Chairs Meeting September 17, 2014 www.energy.gov/EM 2 Procurement Policy Implementation * Ensure contracts align with taxpayer interests and structure contracts so contractors bear responsibility * Hold contractors accountable for overruns due to negligence * Share savings due to better-than-promised performance * Improve

  13. Nevada Test Site DOE/EIS-0243-SA-01

    National Nuclear Security Administration (NNSA)

    Impacts to members of the public from routine airborne emissions of radionuclides were analyzed by evaluating current and planned airborne emissions of radionuclides and the resulting dose to the offsite maximally exposed individual. Impacts to the maximally exposed off-site individual from all sources of airborne emissions of radionuclides in 2000 were less than 2 percent of the 10 millirem annual limit. New emissions from new missions and projects would have a negligible impact on the total

  14. Emerging trends in environmental consultant liability

    SciTech Connect (OSTI)

    Witkin, J.B.

    1995-12-01

    Two federal district judges have recently opened the door for negligence suits aimed specifically an environmental consultants. In William Levy and Harper Realty, Inc. v. Versar, Inc., the respective courts allowed negligence-based claims to survive motions to dismiss, suggesting environmental consultants who fail to discover and/or disclose contamination on the properties they are investigating may be liable for considerable damages, including remediation costs and the economic losses suffered as a result of a claimant`s reliance on the environmental consultant`s work product. These cases poses great concern for environmental consultants. This paper will review these cases in detail, and other legal issues of concern to environmental consultants. It will also review the steps consultants can take to limit their liability, including obtaining errors and omissions insurance, using properly drafted environmental services agreements, properly training their employees, effectively communicating about risks with their clients, and other risk management techniques. In light of the exorbitant costs of environmental clean up, and the expansive breadth of liability imposed by federal environmental laws, consultants need to understand the potential causes of action that can be brought against them. Two federal district judges from Illinois have recently opened the door for negligence suits aimed specifically at environmental consultants, in William Levy and Harper Realty, Inc. v. Versar Inc. This paper will analyze the versar and Mobil Oil cases in detail. It will also explore other issues on professional liability generally of concern to environmental consultants. Finally, suggestion are briefly offered to guide environmental consultants as they embark on clean up activities, to reduce their potential liability to third parties.

  15. Doping suppression and mobility enhancement of graphene transistors fabricated using an adhesion promoting dry transfer process

    SciTech Connect (OSTI)

    Cheol Shin, Woo; Hun Mun, Jeong; Yong Kim, Taek; Choi, Sung-Yool; Jin Cho, Byung E-mail: tskim1@kaist.ac.kr; Yoon, Taeshik; Kim, Taek-Soo E-mail: tskim1@kaist.ac.kr

    2013-12-09

    We present the facile dry transfer of graphene synthesized via chemical vapor deposition on copper film to a functional device substrate. High quality uniform dry transfer of graphene to oxidized silicon substrate was achieved by exploiting the beneficial features of a poly(4-vinylphenol) adhesive layer involving a strong adhesion energy to graphene and negligible influence on the electronic and structural properties of graphene. The graphene field effect transistors (FETs) fabricated using the dry transfer process exhibit excellent electrical performance in terms of high FET mobility and low intrinsic doping level, which proves the feasibility of our approach in graphene-based nanoelectronics.

  16. Inelastic transport through Aharonov-Bohm interferometer in Kondo regime

    SciTech Connect (OSTI)

    Yoshii, Ryosuke; Eto, Mikio; Sakano, Rui; Affleck, Ian

    2013-12-04

    We formulate elastic and inelastic parts of linear conductance through an Aharonov-Bohm (AB) ring with an embedded quantum dot in the Kondo regime. The inelastic part G{sub inel} is proportional to T{sup 2} when the temperature T is much smaller than the Kondo temperature T{sub K}, whereas it is negligibly small compared with elastic part G{sub el} when T ? T{sub K}. G{sub inel} weakly depends on the magnetic flux penetrating the AB ring, which disturbs the precise detection of G{sub el}/(G{sub el}+G{sub inel}) by the visibility of AB oscillation.

  17. Enhanced retained dose uniformity in NiTi spinal correction rod treated by three-dimensional mesh-assisted nitrogen plasma immersion ion implantation

    SciTech Connect (OSTI)

    Lu, Q. Y.; Hu, T.; Kwok, Dixon T. K.; Chu, Paul K.

    2010-05-15

    Owing to the nonconformal plasma sheath in plasma immersion ion implantation of a rod sample, the retained dose can vary significantly. The authors propose to improve the implant uniformity by introducing a metal mesh. The depth profiles obtained with and without the mesh are compared and the implantation temperature at various locations is evaluated indirectly by differential scanning calorimeter. Our results reveal that by using the metal mesh, the retained dose uniformity along the length is greatly improved and the effects of the implantation temperature on the localized mechanical properties of the implanted NiTi shape memory alloy rod are nearly negligible.

  18. Recovery of Mo/Si multilayer coated optical substrates

    DOE Patents [OSTI]

    Baker, S.L.; Vernon, S.P.; Stearns, D.G.

    1997-12-16

    Mo/Si multilayers are removed from superpolished ZERODUR and fused silica substrates with a dry etching process that, under suitable processing conditions, produces negligible change in either the substrate surface figure or surface roughness. The two step dry etching process removes SiO{sub 2} overlayer with a fluroine-containing gas and then moves molybdenum and silicon multilayers with a chlorine-containing gas. Full recovery of the initial normal incidence extreme ultra-violet (EUV) reflectance response has been demonstrated on reprocessed substrates. 5 figs.

  19. Recovery of Mo/Si multilayer coated optical substrates

    DOE Patents [OSTI]

    Baker, Sherry L.; Vernon, Stephen P.; Stearns, Daniel G.

    1997-12-16

    Mo/Si multilayers are removed from superpolished ZERODUR and fused silica substrates with a dry etching process that, under suitable processing conditions, produces negligible change in either the substrate surface figure or surface roughness. The two step dry etching process removes SiO.sub.2 overlayer with a fluroine-containing gas and then moves molybdenum and silicon multilayers with a chlorine-containing gas. Full recovery of the initial normal incidence extreme ultra-violet (EUV) reflectance response has been demonstrated on reprocessed substrates.

  20. Calculation of anharmonic couplings and THz linewidths in crystalline PETN

    SciTech Connect (OSTI)

    Pereverzev, Andrey Sewell, Thomas D. Thompson, Donald L.

    2014-03-14

    We have developed a method for calculating the cubic anharmonic couplings in molecular crystals for normal modes with the zero wave vector in the framework of classical mechanics, and have applied it, combined with perturbation theory, to obtain the linewidths of all infrared absorption lines of crystalline pentaerythritol tetranitrate in the terahertz region (<100 cm{sup ?1}). Contributions of the up- and down-conversion processes to the total linewidth were calculated. The computed linewidths are in qualitative agreement with experimental data and the results of molecular dynamics simulations. Quantum corrections to the linewidths in the terahertz region are shown to be negligible.

  1. ANALYSIS OF HARRELL MONOSODIUM TITANATE LOT #s 46000606120, 46000722120, AND 46000808120

    SciTech Connect (OSTI)

    Taylor-Pashow, K.

    2012-10-08

    Monosodium titanate (MST) for use in the Actinide Removal Process (ARP) must be qualified and verified in advance. A single qualification sample for each batch of material is sent to SRNL for analysis, as well as a statistical sampling of verification samples. The Harrell Industries Lot #s 46000706120, 46000722120, and 460008081120 qualification and verification samples met each of the selected specification requirements that were tested with the exception of a few pails being marginally below the lower weight percent solids limit. These deviations from the specifications are viewed as negligible since the corresponding density of the slurries indicates no appreciable shortage of MST solids. Therefore, SRNL recommends acceptance and use of these pails.

  2. Robust broadcast-communication control of electric vehicle charging

    SciTech Connect (OSTI)

    Chertkov, Michael; Turitsyn, Konstantin; Sulc, Petr; Backhaus, Scott

    2010-01-01

    The anticipated increase in the number of plug-in electric vehicles (EV) will put additional strain on electrical distribution circuits. Many control schemes have been proposed to control EV charging. Here, we develop control algorithms based on randomized EV charging start times and simple one-way broadcast communication allowing for a time delay between communication events. Using arguments from queuing theory and statistical analysis, we seek to maximize the utilization of excess distribution circuit capacity while keeping the probability of a circuit overload negligible.

  3. Process for forming silicon carbide films and microcomponents

    DOE Patents [OSTI]

    Hamza, A.V.; Balooch, M.; Moalem, M.

    1999-01-19

    Silicon carbide films and microcomponents are grown on silicon substrates at surface temperatures between 900 K and 1700 K via C{sub 60} precursors in a hydrogen-free environment. Selective crystalline silicon carbide growth can be achieved on patterned silicon-silicon oxide samples. Patterned SiC films are produced by making use of the high reaction probability of C{sub 60} with silicon at surface temperatures greater than 900 K and the negligible reaction probability for C{sub 60} on silicon dioxide at surface temperatures less than 1250 K. 5 figs.

  4. Hermetic G-16 percussion primer

    SciTech Connect (OSTI)

    Durand, N.A.; Weinmaster, R.R.; Massis, T.M.

    1988-01-01

    Studies were conducted to optimize a Hermetic percussion primer capable of surviving temperatures of 200/degree/C for up to 48 hours. These studies included work with typical brass percussion primers and the pyrotechnic composition designed G-16. The G-16 mixture is composed of antimony sulfide, calcium silicide, and potassium. The hermetically sealed assembly consists of a brass cup and anvil loaded with G-16 pyrotechnic mixture and assembly includes a steel disc which is laser welded over the sealing mechanisms cause negligible changes. This assembly can be used with other primers and is capable of enhanced output for specialized applications. 4 refs., 8 figs., 4 tabs.

  5. Current Renewable Energy Technologies and Future Projections

    SciTech Connect (OSTI)

    Allison, Stephen W; Lapsa, Melissa Voss; Ward, Christina D; Smith, Barton; Grubb, Kimberly R; Lee, Russell

    2007-05-01

    The generally acknowledged sources of renewable energy are wind, geothermal, biomass, solar, hydropower, and hydrogen. Renewable energy technologies are crucial to the production and utilization of energy from these regenerative and virtually inexhaustible sources. Furthermore, renewable energy technologies provide benefits beyond the establishment of sustainable energy resources. For example, these technologies produce negligible amounts of greenhouse gases and other pollutants in providing energy, and they exploit domestically available energy sources, thereby reducing our dependence on both the importation of fossil fuels and the use of nuclear fuels. The market price of renewable energy technologies does not reflect the economic value of these added benefits.

  6. Vacuum leak detector and method

    DOE Patents [OSTI]

    Edwards, Jr., David (7 Brown's La., Bellport, NY 11713)

    1983-01-01

    Apparatus and method for detecting leakage in a vacuum system involves a moisture trap chamber connected to the vacuum system and to a pressure gauge. Moisture in the trap chamber is captured by freezing or by a moisture adsorbent to reduce the residual water vapor pressure therein to a negligible amount. The pressure gauge is then read to determine whether the vacuum system is leaky. By directing a stream of carbon dioxide or helium at potentially leaky parts of the vacuum system, the apparatus can be used with supplemental means to locate leaks.

  7. Gravitomagnetic gyroscope precession in Palatini f(R) gravity

    SciTech Connect (OSTI)

    Ruggiero, Matteo Luca

    2009-04-15

    We study gravitomagnetic effects in the Palatini formalism of f(R) gravity. On using the Kerr-de Sitter metric, which is a solution of f(R) field equations, we calculate the impact of f(R) gravity on the gravitomagnetic precession of an orbiting gyroscope. We show that, even though an f(R) contribution is present in principle, its magnitude is negligibly small and far to be detectable in the present (like GP-B) and foreseeable space missions or observational tests around the Earth.

  8. A=4HE (1992TI02)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    He (1992TI02) (See Energy Level Diagrams for 4He) GENERAL: Ground state:Due to non-central forces, the wave function for the Jπ = 0+ ground state of 4He can be a positive-parity mixture of three 1S0, six 3P0, and five 5D0 orthogonal states (1967BE74). Of course, the symmetric S-wave component is the dominant part of the wavefunction, with significant D-wave and almost negligible P-wave contributions. Since the D-state admixture can be inferred from measurements such as the tensor analyzing

  9. A Monolithic Interconnected module with a tunnel Junction for Enhanced Electrical and Optical Performance

    SciTech Connect (OSTI)

    Murray, Christopher Sean; Wilt, David Morgan

    1999-06-30

    An improved thermophotovoltaic (TPV) n/p/n device is provided. Monolithic Interconnected Modules (MIMs), semiconductor devices converting infrared radiation to electricity, have been developed with improved electrical and optical performance. The structure is an n-type emitter on a p-type base with an n-type lateral conduction layer. The incorporation of a tunnel junction and the reduction in the amount of p-type material used results in negligible parasitic absorption, decreased series resistance, increased voltage and increased active area. The novel use of a tunnel junction results in the potential for a TPV device with efficiency greater than 24%.

  10. Influence of pulse duration, energy, and focusing on laser-assisted water condensation

    SciTech Connect (OSTI)

    Petit, Y.; Henin, S.; Kasparian, J.; Wolf, J. P.; Rohwetter, P.; Stelmaszczyk, K.; Hao, Z. Q.; Nakaema, W. M.; Woeste, L.; Vogel, A.; Pohl, T.; Weber, K.

    2011-01-24

    We investigate the influence of laser parameters on laser-assisted water condensation in the atmosphere. Pulse energy is the most critical parameter. Nanoparticle generation depends linearly on energy beyond the filamentation threshold. Shorter pulses are more efficient than longer ones with saturation at {approx}1.5 ps. Multifilamenting beams appear more efficient than strongly focused ones in triggering the condensation and growth of submicronic particles, while polarization has a negligible influence on the process. The data suggest that the initiation of laser-assisted condensation relies on the photodissociation of the air molecules rather than on their photoionization.

  11. House Testimony | Jefferson Lab

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    House Testimony October 6, 2009 When I took on the role of director, one of the remarks I made to the search committee was that I imagined that the spectrum of interactions with politicians would be an area in which I would be challenged. My experience to that point had been minimal, and my understanding of how it worked was negligible. After a year in the position, I still feel myself to be a neophyte. I still grope for how to say things and when to say them. But my education is fairly intense.

  12. Passivation Effects in Copper Thin Films (Journal Article) | SciTech

    Office of Scientific and Technical Information (OSTI)

    Connect Passivation Effects in Copper Thin Films Citation Details In-Document Search Title: Passivation Effects in Copper Thin Films We studied the influence of a 10 nm AlxOy passivation on the stress-temperature behavior of 100 nm and 1 {mu}m thick Cu films. At low temperatures, the passivation induces a large tensile stress increase in the 100 nm film; however, its effect on the 1 {mu}m film is negligible. At high temperatures, the opposite behavior is observed; while the passivation does

  13. Numerical calculation of the ion polarization in MEIC

    SciTech Connect (OSTI)

    Derbenev, Yaroslav; Lin, Fanglei; Morozov, Vasiliy; Zhang, Yuhong; Kondratenko, Anatoliy; Kondratenko, M A; Filatov, Yury

    2015-09-01

    Ion polarization in the Medium-energy Electron-Ion Collider (MEIC) is controlled by means of universal 3D spin rotators designed on the basis of "weak" solenoids. We use numerical calculations to demonstrate that the 3D rotators have negligible effect on the orbital properties of the ring. We present calculations of the polarization dynamics along the collider's orbit for both longitudinal and transverse polarization directions at a beam interaction point. We calculate the degree of depolarization due to the longitudinal and transverse beam emittances in case when the zero-integer spin resonance is compensated.

  14. Ideal solar cell equation in the presence of photon recycling

    SciTech Connect (OSTI)

    Lan, Dongchen Green, Martin A.

    2014-11-07

    Previous derivations of the ideal solar cell equation based on Shockley's p-n junction diode theory implicitly assume negligible effects of photon recycling. This paper derives the equation in the presence of photon recycling that modifies the values of dark saturation and light-generated currents, using an approach applicable to arbitrary three-dimensional geometries with arbitrary doping profile and variable band gap. The work also corrects an error in previous work and proves the validity of the reciprocity theorem for charge collection in such a more general case with the previously neglected junction depletion region included.

  15. Adsorption of silver dimer on graphene - A DFT study

    SciTech Connect (OSTI)

    Kaur, Gagandeep, E-mail: gaganj1981@yahoo.com [Department of Physics and Centre of Advanced Studies in Physics, Panjab University, Chandigarh-160014, India and Chandigarh Engineering College, Landran, Mohali-140307, Punjab (India); Gupta, Shuchi [Department of Physics and Centre of Advanced Studies in Physics, Panjab University, Chandigarh-160014, India and University Institute of Engineering and Technology, Panjab University, Chandigarh -160014 (India); Rani, Pooja; Dharamvir, Keya [Department of Physics and Centre of Advanced Studies in Physics, Panjab University, Chandigarh-160014 (India)

    2014-04-24

    We performed a systematic density functional theory (DFT) study of the adsorption of silver dimer (Ag{sub 2}) on graphene using SIESTA (Spanish Initiative for Electronic Simulations with Thousands of Atoms) package, in the generalized gradient approximation (GGA). The adsorption energy, geometry, and charge transfer of Ag2-graphene system are calculated. The minimum energy configuration for a silver dimer is parallel to the graphene sheet with its two atoms directly above the centre of carbon-carbon bond. The negligible charge transfer between the dimer and the surface is also indicative of a weak bond. The methodology demonstrated in this paper may be applied to larger silver clusters on graphene sheet.

  16. Impact of graphene polycrystallinity on the performance of graphene field-effect transistors

    SciTech Connect (OSTI)

    Jimnez, David; Chaves, Ferney [Departament d'Enginyeria Electrnica, Escola d'Enginyeria, Universitat Autnoma de Barcelona, 08193-Bellaterra (Spain); Cummings, Aron W.; Van Tuan, Dinh [ICN2, Institut Catal de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain); Kotakoski, Jani [Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Wien (Austria); Department of Physics, University of Helsinki, P.O. Box 43, 00014 University of Helsinki (Finland); Roche, Stephan [ICN2, Institut Catal de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain); ICREA, Instituci Catalana de Recerca i Estudis Avanats, 08070 Barcelona (Spain)

    2014-01-27

    We have used a multi-scale physics-based model to predict how the grain size and different grain boundary morphologies of polycrystalline graphene will impact the performance metrics of graphene field-effect transistors. We show that polycrystallinity has a negative impact on the transconductance, which translates to a severe degradation of the maximum and cutoff frequencies. On the other hand, polycrystallinity has a positive impact on current saturation, and a negligible effect on the intrinsic gain. These results reveal the complex role played by graphene grain boundaries and can be used to guide the further development and optimization of graphene-based electronic devices.

  17. Results of First Outdoor Comparison Between Absolute Cavity Pyrgeometer (ACP) and Infrared Integrating Sphere (IRIS) Radiometer at PMOD (Presentation)

    SciTech Connect (OSTI)

    Reda, I.; Grobner, J.; Wacker, S.; Stoffel, T.

    2013-03-01

    The ACP and IRIS are developed to establish a world reference for calibrating pyrgeometers with traceability to SI units. The two radiometers are unwindowed with negligible spectral dependence, and traceable to SI units through the temperature scale (ITS-90). The first outdoor comparison between the two designs was held from January 28 to February 8, 2013 at the Physikalisch-Metorologisches Observatorium Davos (PMOD). The difference between the irradiance measured by ACP and that of IRIS was within 1 W/m2. A difference of 5 W/m2 was observed between the irradiance measured by ACP&IRIS and that of the interim World Infrared Standard Group (WISG).

  18. Monolithic interconnected module with a tunnel junction for enhanced electrical and optical performance

    DOE Patents [OSTI]

    Murray, Christopher S. (Bethel Park, PA); Wilt, David M. (Bay Village, OH)

    2000-01-01

    An improved thermophotovoltaic (TPV) n/p/n device is provided. Monolithic Interconnected Modules (MIMS), semiconductor devices converting infrared radiation to electricity, have been developed with improved electrical and optical performance. The structure is an n-type emitter on a p-type base with an n-type lateral conduction layer. The incorporation of a tunnel junction and the reduction in the amount of p-type material used results in negligible parasitic absorption, decreased series resistance, increased voltage and increased active area. The novel use of a tunnel junction results in the potential for a TPV device with efficiency greater than 24%.

  19. Negative to positive magnetoresistance and magnetocaloric effect in

    Office of Scientific and Technical Information (OSTI)

    Pr0.6Er0.4Al2 (Journal Article) | DOE PAGES Negative to positive magnetoresistance and magnetocaloric effect in Pr0.6Er0.4Al2 Title: Negative to positive magnetoresistance and magnetocaloric effect in Pr0.6Er0.4Al2 We report on the magnetic, magnetocaloric and magnetotransport properties of Pr0.6Er0.4Al2. The title compound exhibits a large positive magnetoresistance (MR) for H ≥ 40 kOe and a small but non negligible negative MR for H ≤ 30 kOe. The maximum positive MR reaches 13% at H =

  20. Tracking single-particle rotation during macrophage uptake

    SciTech Connect (OSTI)

    Sanchez, Lucero; Patton, Paul; Anthony, Stephen Michael; Yi, Yi; Yu, Yan

    2015-06-10

    We investigated the rotational dynamics of single microparticles during their internalization by macrophage cells. The microparticles used were triblock patchy particles that display two fluorescent patches on their two poles. The optical anisotropy made it possible to directly visualize and quantify the orientation and rotation of the particles. We show that particles exhibit a mixture of fast and slow rotation as they are uptaken by macrophages and transiently undergo directional rotation during their entry into the cell. As a result, the size of the particles and the surface presentation of ligands exerted a negligible influence on this heterogeneity of particle rotation.

  1. Direct Measurements of an increased threshold for stimulated Brillouin scattering with polarization smoothing in ignition hohlraum plasmas

    SciTech Connect (OSTI)

    Froula, D; Divol, L; Berger, R L; London, R; Meezan, N; Neumayer, P; Ross, J S; Stagnito, S; Suter, L; Glenzer, S H; Strozzi, D

    2007-11-08

    We demonstrate a significant reduction of stimulated Brillouin scattering by polarization smoothing. The intensity threshold is measured to increase by a factor of 1.7 {+-} 0.2 when polarization smoothing is applied. The results were obtained in a high-temperature (T{sub 3} {approx_equal} 3 keV) hohlraum plasma where filamentation is negligible in determining the backscatter threshold. These results are explained by an analytical model relevant to ICF plasma conditions that modifies the linear gain exponent to account for polarization smoothing.

  2. Tracking single-particle rotation during macrophage uptake

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sanchez, Lucero; Patton, Paul; Anthony, Stephen Michael; Yi, Yi; Yu, Yan

    2015-06-10

    We investigated the rotational dynamics of single microparticles during their internalization by macrophage cells. The microparticles used were triblock patchy particles that display two fluorescent patches on their two poles. The optical anisotropy made it possible to directly visualize and quantify the orientation and rotation of the particles. We show that particles exhibit a mixture of fast and slow rotation as they are uptaken by macrophages and transiently undergo directional rotation during their entry into the cell. As a result, the size of the particles and the surface presentation of ligands exerted a negligible influence on this heterogeneity of particlemore » rotation.« less

  3. Microsoft PowerPoint - NEILS for HTF page 1_ebf.ppt [Compatibility Mode]

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    A good HTF must be able to absorb a substantial amount of energy in a given volume, a property known as volumetric heat capacity. Physical properties such as viscosity, thermal stability, and thermal conductivity must also be considered. Ionic liquids (IL) were discovered more than 30 years ago and are organic compounds with negligible vapor pressure. ILs are molten salts with low melting points below 100°C, high liquid range above 400°C, in some cases, freezing points below 0°C. For example,

  4. Electronic band structure imaging of three layer twisted graphene on single crystal Cu(111)

    SciTech Connect (OSTI)

    Marquez Velasco, J.; Department of Physics, National Technical University of Athens, Athens ; Kelaidis, N.; Xenogiannopoulou, E.; Tsoutsou, D.; Tsipas, P.; Speliotis, Th.; Pilatos, G.; Likodimos, V.; Falaras, P.; Dimoulas, A.; Raptis, Y. S.

    2013-11-18

    Few layer graphene (FLG) is grown on single crystal Cu(111) by Chemical Vapor Deposition, and the electronic valence band structure is imaged by Angle-Resolved Photo-Emission Spectroscopy. It is found that graphene essentially grows polycrystalline. Three nearly ideal Dirac cones are observed along the Cu ?{sup }K{sup } direction in k-space, attributed to the presence of ?4 twisted three layer graphene with negligible interlayer coupling. The number of layers and the stacking order are compatible with Raman data analysis demonstrating the complementarity of the two techniques for a more accurate characterization of FLG.

  5. Process for forming silicon carbide films and microcomponents

    DOE Patents [OSTI]

    Hamza, Alex V. (Livermore, CA); Balooch, Mehdi (Berkeley, CA); Moalem, Mehran (Berkeley, CA)

    1999-01-01

    Silicon carbide films and microcomponents are grown on silicon substrates at surface temperatures between 900 K and 1700 K via C.sub.60 precursors in a hydrogen-free environment. Selective crystalline silicon carbide growth can be achieved on patterned silicon-silicon oxide samples. Patterned SiC films are produced by making use of the high reaction probability of C.sub.60 with silicon at surface temperatures greater than 900 K and the negligible reaction probability for C.sub.60 on silicon dioxide at surface temperatures less than 1250 K.

  6. Spin-current diode with a ferromagnetic semiconductor

    SciTech Connect (OSTI)

    Sun, Qing-Feng Xie, X. C.

    2015-05-04

    Diode is a key device in electronics: the charge current can flow through the device under a forward bias, while almost no current flows under a reverse bias. Here, we propose a corresponding device in spintronics: the spin-current diode, in which the forward spin current is large but the reversed one is negligible. We show that the lead/ferromagnetic quantum dot/lead system and the lead/ferromagnetic semiconductor/lead junction can work as spin-current diodes. The spin-current diode, a low dissipation device, may have important applications in spintronics, as the conventional charge-current diode does in electronics.

  7. Letter, Arthur C. Compton to Enrico Fermi, September 14, 1942, "Establishing Site X"

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ontheaain,Sasurday,I~ttuDugh~e~nt6sol,~~wocrJuldsa6efy~rhanacrianatgingthc~-si~ p~cuptoa~~~afProrn10to100~~abwe~iRidatvaIue. Asyouhavedoubllessibundforyourself~alOdegreoC riscioquins~ughIyl000k#~wadhours,nnd~an~~torhcunshIoldedpifctoabme50rofgammataysphtr~~ tImesesmuohneunnnmdl&n. ~gming~p~ng~~giba~~leshicldofbl~ofparaffin,cadmiamand~at cement blocka, this could be readily reduced to a negligible qmtity foraslngle dose, A month after qcration, a 1 kg bIock of metal vmxld have an acdvityof 1

  8. Integrated Modeling of Building Energy Requirements IncorporatingSolar Assisted Cooling

    SciTech Connect (OSTI)

    Firestone, Ryan; Marnay, Chris; Wang, Juan

    2005-08-10

    This paper expands on prior Berkeley Lab work on integrated simulation of building energy systems by the addition of active solar thermal collecting devices, technology options not previously considered (Siddiqui et al 2005). Collectors can be used as an alternative or additional source of hot water to heat recovery from reciprocating engines or microturbines. An example study is presented that evaluates the operation of solar assisted cooling at a large mail sorting facility in southern California with negligible heat loads and year-round cooling loads. Under current conditions solar thermal energy collection proves an unattractive option, but is a viable carbon emission control strategy.

  9. The effects of heat conduction on the vaporization of liquid invading superheated permeable rock

    SciTech Connect (OSTI)

    Woods, Andrew, W.; Fitzgerald, Shaun D.

    1996-01-24

    We examine the role of conductive and convective heat transfer in the vaporization of liquid as it slowly invades a superheated permeable rock. For very slow migration, virtually all of the liquid vaporizes. As the liquid supply rate increases beyond the rate of heat transfer by thermal conduction, a decreasing fraction of the liquid can vaporize. Indeed, for sufficiently high flow rates, the fraction vaporizing depends solely on the superheat of the rock, and any heat transfer from the superheated region is negligible. These results complement earlier studies of vaporization under very high injection rates, in which case the dynamic vapour pressure reduces the mass fraction vaporizing to very small values.

  10. Active Climate Stabilization: Practical Physics-Based Approaches to Prevention of Climate Change

    DOE R&D Accomplishments [OSTI]

    Teller, E.; Hyde, T.; Wood, L.

    2002-04-18

    We offer a case for active technical management of the radiative forcing of the temperatures of the Earth's fluid envelopes, rather than administrative management of atmospheric greenhouse gas inputs, in order to stabilize both the global- and time-averaged climate and its mesoscale features. We suggest that active management of radiative forcing entails negligible--indeed, likely strongly negative--economic costs and environmental impacts, and thus best complies with the pertinent mandate of the UN Framework Convention on Climate Change. We propose that such approaches be swiftly evaluated in sub-scale in the course of an intensive international program.

  11. Relativistic Point Coupling Model for Vibrational Excitations in the Continuum

    SciTech Connect (OSTI)

    Ring, P.; Daoutidis, J.; Litvinova, E.; Niksic, T.; Paar, N.; Vretenar, D.

    2009-08-26

    An implementation of the relativistic random phase approximation with the proper treatment of the continuum has been developed for the relativistic point coupling model and applied to investigate collective excitations in spherical nuclei. The results are compared with the spectral implementation of the same model. In heavy nuclei, where the escape width is negligible, we find an excellent agreement between both methods in the region of giant resonance and some discrepancies in the region of low-lying pygmy resonance. The differences are more pronounced in light nuclei due to the larger values of the escape widths.

  12. An ultra-thin diamond membrane as a transmission particle detector and vacuum window for external microbeams

    SciTech Connect (OSTI)

    Grilj, V.; Skukan, N.; Jaki?, M.; Pomorski, M.; Kada, W.; Iwamoto, N.; Kamiya, T.; Ohshima, T.

    2013-12-09

    Several applications of external microbeam techniques demand a very accurate and controlled dose delivery. To satisfy these requirements when post-sample ion detection is not feasible, we constructed a transmission single-ion detector based on an ultra-thin diamond membrane. The negligible intrinsic noise provides an excellent signal-to-noise ratio and enables a hit-detection efficiency of close to 100%, even for energetic protons, while the small thickness of the membrane limits beam spreading. Moreover, because of the superb mechanical stiffness of diamond, this membrane can simultaneously serve as a vacuum window and allow the extraction of an ion microbeam into the atmosphere.

  13. Operation Sandstone. Scientific Director's report of atomic-weapon tests at Eniwetok, 1948. Annex 8. Gamma-ray measurements. Parts 1, 2, 3, 4, and 5. Sandstone report No. 29

    SciTech Connect (OSTI)

    Shonka, F.R.; Pawlicki, G.S.

    1985-09-01

    Curves of absorption of gamma rays in boron carbide and a few points on the absorption curve in lead were obtained during the three atomic explosions of Operation Sandstone. Radiation was detected by integrating ionization chambers and by photographic emulsions. A few recording-type ionization chambers were used to give intensities as a function of time. Radiation detectors were located inside of shelters which protected them from blast and shielded them from scattered radiation. Because of geometry, scattered radiation was negligible and the analysis of absorption curves yields the true total absorption coefficient for the radiation.

  14. Glucose Biosensor Based on Immobilization of Glucose Oxidase in Platinum Nanoparticles/Graphene/Chitosan Nanocomposite Film

    SciTech Connect (OSTI)

    Wu, Hong; Wang, Jun; Kang, Xinhuang; Wang, Chong M.; Wang, Donghai; Liu, Jun; Aksay, Ilhan A.; Lin, Yuehe

    2009-09-01

    The bionanocomposite film consisting of glucose oxidase/Pt/functional graphene sheets/chitosan (GOD/Pt/FGS/chitosan) for glucose sensing was described. With the electrocatalytic synergy of FGS and Pt nanoparticles to hydrogen peroxide, a sensitive biosensor with detection limit of 0.6 M glucose was achieved. The biosensor also had good reproducibility, long term stability and negligible interfering signals from ascorbic acid and uric acid comparing to the response to glucose. The large surface area and good conductivity of graphene suggests that graphene is a potential candidate for sensor material. The hybrid nanocomposite glucose sensor provides new opportunity for clinical diagnosis and point-of-care applications.

  15. Laser machining of explosives

    DOE Patents [OSTI]

    Perry, Michael D. (Livermore, CA); Stuart, Brent C. (Fremont, CA); Banks, Paul S. (Livermore, CA); Myers, Booth R. (Livermore, CA); Sefcik, Joseph A. (Tracy, CA)

    2000-01-01

    The invention consists of a method for machining (cutting, drilling, sculpting) of explosives (e.g., TNT, TATB, PETN, RDX, etc.). By using pulses of a duration in the range of 5 femtoseconds to 50 picoseconds, extremely precise and rapid machining can be achieved with essentially no heat or shock affected zone. In this method, material is removed by a nonthermal mechanism. A combination of multiphoton and collisional ionization creates a critical density plasma in a time scale much shorter than electron kinetic energy is transferred to the lattice. The resulting plasma is far from thermal equilibrium. The material is in essence converted from its initial solid-state directly into a fully ionized plasma on a time scale too short for thermal equilibrium to be established with the lattice. As a result, there is negligible heat conduction beyond the region removed resulting in negligible thermal stress or shock to the material beyond a few microns from the laser machined surface. Hydrodynamic expansion of the plasma eliminates the need for any ancillary techniques to remove material and produces extremely high quality machined surfaces. There is no detonation or deflagration of the explosive in the process and the material which is removed is rendered inert.

  16. Exact analytical solution of the linear structure growth rate in {Lambda}CDM cosmology and its cosmological applications

    SciTech Connect (OSTI)

    Zhang Pengjie [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Science, 80 Nandan Road, Shanghai, China, 200030 (China)

    2011-03-15

    We derive the exact analytical solution of the linear structure growth rate in {Lambda}CDM cosmology with flat or curved geometry, under the Newtonian gauge. Unlike the well known solution under the Newtonian limit [D. J. Heath, Mon. Not. R. Astron. Soc. 179, 351 (1977)], our solution takes all general relativistic corrections into account and is hence valid at both the sub- and superhorizon scales. With this exact solution, we evaluate cosmological impacts induced by these relativistic corrections. (1) General relativistic corrections alter the density growth from z=100 to z=0 by 10% at k=0.01 h/Mpc and the impact becomes stronger toward larger scales. We caution the readers that the overdensity is not gauge invariant and the above statement is restrained to the Newtonian gauge. (2) Relativistic corrections introduce a k{sup -2} scale dependence in the density fluctuation. It mimics a primordial non-Gaussianity of the local type with f{sub NL}{sup local{approx}}1. This systematical error may become non-negligible for future all sky deep galaxy surveys. (3) Cosmological simulations with box size greater than 1 Gpc are also affected by these relativistic corrections. We provide a postprocessing recipe to correct for these effects. (4) These relativistic corrections affect the redshift distortion. However, at redshifts and scales relevant to redshift distortion measurements, such effect is negligible.

  17. Introduction of a methoxymethyl side chain into p-phenylenediamine attenuates its sensitizing potency and reduces the risk of allergy induction

    SciTech Connect (OSTI)

    Goebel, Carsten; Troutman, John; Hennen, Jenny; Rothe, Helga; Schlatter, Harald; Gerberick, G. Frank; Blmeke, Brunhilde

    2014-02-01

    The strong sensitizing potencies of the most important primary intermediates of oxidative hair dyes, p-phenylenediamine (PPD) and p-toluylenediamine (PTD, i.e. 2-methyl-PPD) are well established. They are considered as the key sensitizers in hair dye allergic contact dermatitis. While modification of their molecular structure is expected to alter their sensitizing properties, it may also impair their color performance. With introduction of a methoxymethyl side chain we found the primary intermediate 2-methoxymethyl-p-phenylenediamine (ME-PPD) with excellent hair coloring performance but significantly reduced sensitizing properties compared to PPD and PTD: In vitro, ME-PPD showed an attenuated innate immune response when analyzed for its protein reactivity and dendritic cell activation potential. In vivo, the effective concentration of ME-PPD necessary to induce an immune response 3-fold above vehicle control (EC3 value) in the local lymph node assay (LLNA) was 4.3%, indicating a moderate skin sensitizing potency compared to values of 0.1 and 0.17% for PPD and PTD, respectively. Finally, assessing the skin sensitizing potency of ME-PPD under consumer hair dye usage conditions through a quantitative risk assessment (QRA) indicated an allergy induction risk negligible compared to PPD or PTD. - Highlights: Methoxymethyl side chain in p-phenylenediamine reduces its strong skin sensitizing properties. Reduced protein reactivity and dendritic cell activation. Reduced skin sensitizing potency in local lymph node assay (LLNA). Negligible allergy induction risk under hair dye usage conditions.

  18. Fast dose kernel interpolation using Fourier transform with application to permanent prostate brachytherapy dosimetry

    SciTech Connect (OSTI)

    Liu, Derek Sloboda, Ron S.

    2014-05-15

    Purpose: Boyer and Mok proposed a fast calculation method employing the Fourier transform (FT), for which calculation time is independent of the number of seeds but seed placement is restricted to calculation grid points. Here an interpolation method is described enabling unrestricted seed placement while preserving the computational efficiency of the original method. Methods: The Iodine-125 seed dose kernel was sampled and selected values were modified to optimize interpolation accuracy for clinically relevant doses. For each seed, the kernel was shifted to the nearest grid point via convolution with a unit impulse, implemented in the Fourier domain. The remaining fractional shift was performed using a piecewise third-order Lagrange filter. Results: Implementation of the interpolation method greatly improved FT-based dose calculation accuracy. The dose distribution was accurate to within 2% beyond 3 mm from each seed. Isodose contours were indistinguishable from explicit TG-43 calculation. Dose-volume metric errors were negligible. Computation time for the FT interpolation method was essentially the same as Boyer's method. Conclusions: A FT interpolation method for permanent prostate brachytherapy TG-43 dose calculation was developed which expands upon Boyer's original method and enables unrestricted seed placement. The proposed method substantially improves the clinically relevant dose accuracy with negligible additional computation cost, preserving the efficiency of the original method.

  19. Method and apparatus for powering an electrodeless lamp with reduced radio frequency interference

    DOE Patents [OSTI]

    Simpson, J.E.

    1999-06-08

    An electrodeless lamp waveguide structure includes tuned absorbers for spurious RF signals. A lamp waveguide with an integral frequency selective attenuation includes resonant absorbers positioned within the waveguide to absorb spurious out-of-band RF energy. The absorbers have a negligible effect on energy at the selected frequency used to excite plasma in the lamp. In a first embodiment, one or more thin slabs of lossy magnetic material are affixed to the sidewalls of the waveguide at approximately one quarter wavelength of the spurious signal from an end wall of the waveguide. The positioning of the lossy material optimizes absorption of power from the spurious signal. In a second embodiment, one or more thin slabs of lossy magnetic material are used in conjunction with band rejection waveguide filter elements. In a third embodiment, one or more microstrip filter elements are tuned to the frequency of the spurious signal and positioned within the waveguide to couple and absorb the spurious signal's energy. All three embodiments absorb negligible energy at the selected frequency and so do not significantly diminish the energy efficiency of the lamp. 18 figs.

  20. Method and apparatus for powering an electrodeless lamp with reduced radio frequency interference

    DOE Patents [OSTI]

    Simpson, James E.

    1999-01-01

    An electrodeless lamp waveguide structure includes tuned absorbers for spurious RF signals. A lamp waveguide with an integral frequency selective attenuation includes resonant absorbers positioned within the waveguide to absorb spurious out-of-band RF energy. The absorbers have a negligible effect on energy at the selected frequency used to excite plasma in the lamp. In a first embodiment, one or more thin slabs of lossy magnetic material are affixed to the sidewalls of the waveguide at approximately one quarter wavelength of the spurious signal from an end wall of the waveguide. The positioning of the lossy material optimizes absorption of power from the spurious signal. In a second embodiment, one or more thin slabs of lossy magnetic material are used in conjunction with band rejection waveguide filter elements. In a third embodiment, one or more microstrip filter elements are tuned to the frequency of the spurious signal and positioned within the waveguide to couple and absorb the spurious signal's energy. All three embodiments absorb negligible energy at the selected frequency and so do not significantly diminish the energy efficiency of the lamp.

  1. First principles studies of proton conduction in KTaO{sub 3}

    SciTech Connect (OSTI)

    Kang, Sung Gu; Sholl, David S.

    2014-07-14

    KTaO{sub 3} (KTO) is a useful prototypical perovskite for examining the mechanisms of proton transport in perovskites. Previously, Gomez et al. [J. Chem. Phys. 126, 194701 (2007)] reported density functional theory (DFT) calculations describing proton hopping in defect-free KTO. We use DFT calculations to extend that work in two directions, namely, understanding isotope effects in low and high temperature proton transport and the role of native point defects in KTO. At cryogenic temperatures, quantum tunneling plays a vital role in the net hopping of protons in KTO. At the elevated temperature characteristic of applications involving proton-conducting perovskites, tunneling is negligible but zero point energy effects still lead to non-negligible isotope effects for H{sup +}, D{sup +}, and T{sup +}. We also use DFT to characterize the populations of relevant point defects in KTO as a function of experimental conditions, and to examine the migration of protons that are close in proximity to these defects. This information gives useful insight into the overall transport rates of protons through KTO under a variety of external environments. We also assess the overall diffusivity of protons in KTO at various ranges of oxygen vacancy concentrations by performing kinetic Monte Carlo simulations.

  2. Dependence of enhanced asymmetry-induced transport on collision frequency

    SciTech Connect (OSTI)

    Eggleston, D. L.

    2014-07-15

    A single-particle code with collisional effects is used to study how asymmetry-induced radial transport in a non-neutral plasma depends on collision frequency. For asymmetries of the form ?{sub 1}(r)?cos(kz)?cos(?t?l?), two sources for the transport have been identified: resonant particles and axially trapped particles. The simulation shows that this latter type, which occurs near the radius where ? matches the azimuthal rotation frequency ?{sub R}, is usually dominant at low collision frequency ? but becomes negligible at higher ?. This behavior can be understood by noting that axially trapped particles have a lower trapping frequency than resonant particles. In the low ? (banana) regime, the radial oscillations have amplitude ?r???v{sub r}/?{sub T}, so axially trapped particles dominate, and the transport may even exceed the resonant particle plateau regime level. As ? increases, collisions start to interrupt the slower axially trapped particle oscillations, while the resonant particles are still in the banana regime, so the axially trapped particle contribution to the transport decreases. At the largest ? values, axially trapped particle transport is negligible and the observed diffusion coefficient matches that given by plateau regime resonant particle theory. Heuristic models based on these considerations give reasonable agreement with the observed scaling laws for the value of the collision frequency where axially trapped particle transport starts to decrease and for the enhancement of the diffusion coefficient produced by axially trapped particles.

  3. Oxidation of methanol on single crystal platinum electrodes in alkaline solution

    SciTech Connect (OSTI)

    Tripkovic, A.V.; Marinkovic, N.; Adzic, R.R.

    1995-10-01

    Methanol oxidation has been studied on three low-index single crystal Pt electrodes and four stepped surfaces, vicinal to the (111) and (100) orientations in alkaline solutions. Considering the onset of the reaction, it appears that the activity decreases in the sequence Pt(100), Pt(110) and Pt(111). This can also be inferred from the quasi-steady-state measurements. The current peaks, observed at different potentials, show the highest activity of Pt(111). The steps cause increase of the surface activity, but are prone to a fast poisoning. The reaction involves a formation of a small amount of CO on Pt(100) but a negligible amount on Pt(111). This was inferred from the in situ FTIR measurements. Two different reaction mechanisms were identified for the Pt(111) and Pt(100). The data clearly show that a large difference of the activity of Pt for methanol oxidation in acid and alkaline solutions originates in a smaller or negligible poisoning effects in alkaline solutions.

  4. Measurement of tool forces in diamond turning

    SciTech Connect (OSTI)

    Drescher, J.; Dow, T.A.

    1988-12-01

    A dynamometer has been designed and built to measure forces in diamond turning. The design includes a 3-component, piezoelectric transducer. Initial experiments with this dynamometer system included verification of its predicted dynamic characteristics as well as a detailed study of cutting parameters. Many cutting experiments have been conducted on OFHC Copper and 6061-T6 Aluminum. Tests have involved investigation of velocity effects, and the effects of depth and feedrate on tool forces. Velocity has been determined to have negligible effects between 4 and 21 m/s. Forces generally increase with increasing depth of cut. Increasing feedrate does not necessarily lead to higher forces. Results suggest that a simple model may not be sufficient to describe the forces produced in the diamond turning process.

  5. Absence of exchange interaction between localized magnetic moments and conduction-electrons in diluted Er{sup 3+} gold-nanoparticles

    SciTech Connect (OSTI)

    Lesseux, G. G. Urbano, R. R.; Iwamoto, W.; Garca-Flores, A. F.; Rettori, C.

    2014-05-07

    The Electron Spin Resonance (ESR) of diluted Er{sup 3+} magnetic ions in Au nanoparticles (NPs) is reported. The NPs were synthesized by reducing chloro triphenyl-phosphine gold(I) and erbium(III) trifluoroacetate. The Er{sup 3+} g-value along with the observed hyperfine splitting indicate that the Er{sup 3+} impurities are in a local cubic symmetry. Furthermore, the Er{sup 3+} ESR spectra show that the exchange interaction between the 4f and the conduction electrons (ce) is absent or negligible in Au{sub 1x}Er{sub x} NPs, in contrast to the ESR results in bulk Au{sub 1x}Er{sub x}. Therefore, the nature of this interaction needs to be reexamined at the nano scale range.

  6. Third-order nonlinear optical response of colloidal gold nanoparticles prepared by sputtering deposition

    SciTech Connect (OSTI)

    Castro, Hemerson P. S.; Alencar, Mrcio A. R. C.; Hickmann, Jandir M.; Wender, Heberton; Department of Physics, Universidade Federal do Mato Grosso do Sul, 79070-900, Campo Grande ; Teixeira, Sergio R.; Dupont, Jairton

    2013-11-14

    The nonlinear optical responses of gold nanoparticles dispersed in castor oil produced by sputtering deposition were investigated, using the thermally managed Z-scan technique. Particles with spherical shape and 2.6 nm of average diameter were obtained and characterized by transmission electron microscopy and small angle X-ray scattering. This colloid was highly stable, without the presence of chemical impurities, neither stabilizers. It was observed that this system presents a large refractive third-order nonlinear response and a negligible nonlinear absorption. Moreover, the evaluation of the all-optical switching figures of merit demonstrated that the colloidal nanoparticles prepared by sputtering deposition have a good potential for the development of ultrafast photonic devices.

  7. Two-neutron stripping in ({sup 18}O, {sup 16}O) and (t,p) reactions

    SciTech Connect (OSTI)

    Cavallaro, M.; Agodi, A.; Carbone, D.; Cunsolo, A.; Bond, M.; Cappuzzello, F.; Nicolosi, D.; Tropea, S.; Borello-Lewin, T.; Rodrigues, M. R. D.; De Napoli, M.; Garcia, V. N.

    2014-11-11

    The {sup 12}C({sup 18}O,{sup 16}O){sup 14}C reactions has been investigated at 84 MeV incident energy. The charged ejectiles produced in the reaction have been momentum analyzed and identified by the MAGNEX magnetic spectrometer. Q-value spectra have been extracted with an energy resolution of 160 keV (Full Width at Half Maximum) and several known bound and resonant states of {sup 14}C have been identified up to 15 MeV. In particular, excited states with dominant 2p - 4h configuration are the most populated. The absolute values of the cross sections have been extracted showing a striking similarity with those measured for the same transitions by (t,p) reactions. This indicates that the effect of the {sup 16}O core is negligible in the reaction mechanism.

  8. Radiation pressure efficiency measurements of nanoparticle coated microspheres

    SciTech Connect (OSTI)

    Kim, Soo Y.; Taylor, Joseph D.; Ladouceur, Harold D.; Hart, Sean J.; Terray, Alex

    2013-12-02

    Experimental measurements of the radiation pressure efficiency (Q{sub pr}) for several microparticles have been compared to theoretical calculations extrapolated from the Bohren-Huffman code for Mie scattering of coated particles. An increased shift of the Q{sub pr} parameter was observed for 2??m SiO{sub 2} core particles coated with nanoparticles of higher refractive indices. Coatings of 14?nm melamine particles were found to increase the Q{sub pr} parameter 135 times over similar coatings using SiO{sub 2} particles of the same size. While a coating of 100?nm polystyrene particles also showed a significant increase, they did not agree well with theoretical values. It is hypothesized that other factors such as increased scatter, drag, and finite coating coverage are no longer negligible for coatings using nanoparticles in this size regime.

  9. Molten uranium dioxide structure and dynamics

    SciTech Connect (OSTI)

    Skinner, L. B.; Parise, J. B.; Benmore, C. J.; Weber, J. K.R.; Williamson, M. A.; Tamalonis, A.; Hebden, A.; Wiencek, T.; Alderman, O. L.G.; Guthrie, M.; Leibowitz, L.

    2014-11-21

    Uranium dioxide (UO2) is the major nuclear fuel component of fission power reactors. A key concern during severe accidents is the melting and leakage of radioactive UO2 as it corrodes through its zirconium cladding and steel containment. Yet, the very high temperatures (>3140 kelvin) and chemical reactivity of molten UO2 have prevented structural studies. In this work, we combine laser heating, sample levitation, and synchrotron x-rays to obtain pair distribution function measurements of hot solid and molten UO2. The hot solid shows a substantial increase in oxygen disorder around the lambda transition (2670 K) but negligible U-O coordination change. On melting, the average U-O coordination drops from 8 to 6.7 0.5. Molecular dynamics models refined to this structure predict higher U-U mobility than 8-coordinated melts.

  10. The green entrepreneur: Business opportunities that can save the Earth make you money

    SciTech Connect (OSTI)

    Berle, G.

    1993-01-01

    The Green Entrepreneur looks at business opportunities for the many small operators working their way through the landslide. Gustav Berle's book is an alarming cornucopia of good ideas, helpful references, and summaries of today's preoccupying business concerns to reduce waste, save materials, and conserve energy. This quick-read is also interspersed with a lower-octane blend of popularist solutions to such global problems as world hunger, world peace, and the world's needs for resource reallocation. The ideas spread throughout this text may trigger some start-up thoughts, and the many helpful references may assist those eager to learn how to use the backhoe and pick axe. Unfortunately, the small players are probably a small part of the needed answer. The momentous claim of the book - the need to combine environmentally sound concepts with sharp business plans and competent management' - isn't bad nor negligent advice for the giants, either, that still roam the globe.

  11. GHz laser-free time-resolved transmission electron microscopy: A stroboscopic high-duty-cycle method

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Qiu, Jiaqi; Zhu, Yimei; Ha, Gwanghui; Jing, Chunguang; Baryshev, Sergey V.; Reed, Bryan W.; Lau, June W.

    2015-11-10

    In this study, a device and a method for producing ultrashort electron pulses with GHz repetition rates via pulsing an input direct current (dc) electron beam are provided. The device and the method are based on an electromagnetic-mechanical pulser (EMMP) that consists of a series of transverse deflecting cavities and magnetic quadrupoles. The EMMP modulates and chops the incoming dc electron beam and converts it into pico- and sub-pico-second electron pulse sequences (pulse trains) at >1 GHz repetition rates, as well as controllably manipulates the resulting pulses. Ultimately, it leads to negligible electron pulse phase-space degradation compared to the incomingmore » dc beam parameters. The temporal pulse length and repetition rate for the EMMP can be continuously tunable over wide ranges.« less

  12. Cr/sup 3 +/-doped colquiriite solid state laser material

    DOE Patents [OSTI]

    Payne, S.A.; Chase, L.L.; Newkirk, H.W.; Krupke, W.F.

    1988-03-31

    Chromium doped colquiriite, LiCaAlF/sub 6/:Cr/sup 3 +/, is useful as a tunable laser crystal that has a high intrinsic slope efficiency, comparable to or exceeding that of alexandrite, the current leading performer of vibronic sideband Cr/sup 3 +/ lasers. The laser output is tunable from at least 720 nm to 840 nm with a measured slope efficiency of about 60% in a Kr laser pumped laser configuration. The intrinsic slope efficiency (in the limit of large output coupling) may approach the quantum defect limited value of 83%. The high slope efficiency implies that excited state absorption (ESA) is negligible. The potential for efficiency and the tuning range of this material satisfy the requirements for a pump laser for a high density storage medium incorporating Nd/sup 3 +/ or Tm/sup 3 +/ for use in a multimegajoule single shot fusion research facility. 4 figs.

  13. Method for reducing nitrogen oxides in combustion effluents

    DOE Patents [OSTI]

    Zauderer, Bert (Merion Station, PA)

    2000-01-01

    Method for reducing nitrogen oxides (NO.sub.x) in the gas stream from the combustion of fossil fuels is disclosed. In a narrow gas temperature zone, NO.sub.x is converted to nitrogen by reaction with urea or ammonia with negligible remaining ammonia and other reaction pollutants. Specially designed injectors are used to introduce air atomized water droplets containing dissolved urea or ammonia into the gaseous combustion products in a manner that widely disperses the droplets exclusively in the optimum reaction temperature zone. The injector operates in a manner that forms droplet of a size that results in their vaporization exclusively in this optimum NO.sub.x -urea/ammonia reaction temperature zone. Also disclosed is a design of a system to effectively accomplish this injection.

  14. Image intensifier gain uniformity improvements in sealed tubes by selective scrubbing

    DOE Patents [OSTI]

    Thomas, S.W.

    1995-04-18

    The gain uniformity of sealed microchannel plate image intensifiers (MCPIs) is improved by selectively scrubbing the high gain sections with a controlled bright light source. Using the premise that ions returning to the cathode from the microchannel plate (MCP) damage the cathode and reduce its sensitivity, a HeNe laser beam light source is raster scanned across the cathode of a microchannel plate image intensifier (MCPI) tube. Cathode current is monitored and when it exceeds a preset threshold, the sweep rate is decreased 1000 times, giving 1000 times the exposure to cathode areas with sensitivity greater than the threshold. The threshold is set at the cathode current corresponding to the lowest sensitivity in the active cathode area so that sensitivity of the entire cathode is reduced to this level. This process reduces tube gain by between 10% and 30% in the high gain areas while gain reduction in low gain areas is negligible. 4 figs.

  15. On the kinetic barriers of graphene homo-epitaxy

    SciTech Connect (OSTI)

    Zhang, Wei; Yu, Xinke; Xie, Ya-Hong; Cahyadi, Erica; Ratsch, Christian

    2014-12-01

    The diffusion processes and kinetic barriers of individual carbon adatoms and clusters on graphene surfaces are investigated to provide fundamental understanding of the physics governing epitaxial growth of multilayer graphene. It is found that individual carbon adatoms form bonds with the underlying graphene whereas the interaction between graphene and carbon clusters, consisting of 6 atoms or more, is very weak being van der Waals in nature. Therefore, small carbon clusters are quite mobile on the graphene surfaces and the diffusion barrier is negligibly small (?6?meV). This suggests the feasibility of high-quality graphene epitaxial growth at very low growth temperatures with small carbon clusters (e.g., hexagons) as carbon source. We propose that the growth mode is totally different from 3-dimensional bulk materials with the surface mobility of carbon hexagons being the highest over graphene surfaces that gradually decreases with further increase in cluster size.

  16. Enhanced optoelectronic quality of perovskite thin films with hypophosphorous acid for planar heterojunction solar cells

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Wei; Pathak, Sandeep; Sakai, Nobuya; Stergiopoulos, Thomas; Nayak, Pabitra K.; Noel, Nakita K.; Haghighirad, Amir A.; Burlakov, Victor M.; deQuilettes, Dane W.; Sadhanala, Aditya; et al

    2015-11-30

    Solution-processed metal halide perovskite semiconductors, such as CH3NH3PbI3, have exhibited remarkable performance in solar cells, despite having non-negligible density of defect states. A likely candidate is halide vacancies within the perovskite crystals, or the presence of metallic lead, both generated due to the imbalanced I/Pb stoichiometry which could evolve during crystallization. Herein, we show that the addition of hypophosphorous acid (HPA) in the precursor solution can significantly improve the film quality, both electronically and topologically, and enhance the photoluminescence intensity, which leads to more efficient and reproducible photovoltaic devices. We demonstrate that the HPA can reduce the oxidized I2 backmore » into I-, and our results indicate that this facilitates an improved stoichiometry in the perovskite crystal and a reduced density of metallic lead.« less

  17. PEAK READING VOLTMETER

    DOE Patents [OSTI]

    Dyer, A.L.

    1958-07-29

    An improvement in peak reading voltmeters is described, which provides for storing an electrical charge representative of the magnitude of a transient voltage pulse and thereafter measuring the stored charge, drawing oniy negligible energy from the storage element. The incoming voltage is rectified and stored in a condenser. The voltage of the capacitor is applied across a piezoelectric crystal between two parallel plates. Amy change in the voltage of the capacitor is reflected in a change in the dielectric constant of the crystal and the capacitance between a second pair of plates affixed to the crystal is altered. The latter capacitor forms part of the frequency determlning circuit of an oscillator and means is provided for indicating the frequency deviation which is a measure of the peak voltage applied to the voltmeter.

  18. ESR of Gd{sup 3+} in the Kondo-lattice compound YbAgCu{sub 4} and its reference compounds RAgCu{sub 4} (R=Y,Lu)

    SciTech Connect (OSTI)

    Pagliuso, P.G.; Rettori, C.; Oseroff, S.B.; Sarrao, J.; Fisk, Z.; Cornelius, A.; Hundley, M.F.

    1997-10-01

    Low-temperature (T{lt}30thinspK) electron-spin-resonance (ESR) experiments of Gd{sup 3+} diluted in the Kondo-lattice compound YbAgCu{sub 4} and its reference compounds YAgCu{sub 4} and LuAgCu{sub 4} are interpreted in terms of an enhanced density of states at the Fermi level for the Yb-based compound. The results of susceptibility and ESR (Korringa rate and g-shift) measurements show negligible electron-electron exchange enhancement for all the studied compounds. The exchange interaction between the Gd{sup 3+} local moment and the conduction electrons (c-e) is c-e wave vector dependent in all three compounds. {copyright} {ital 1997} {ital The American Physical Society}

  19. Search for supersymmetry in pp collisions at 7 TeV in events with jets and missing transverse energy

    SciTech Connect (OSTI)

    Khachatryan, Vardan; et al.

    2011-04-01

    A search for supersymmetry with R-parity conservation in proton-proton collisions at a centre-of-mass energy of 7 TeV is presented. The data correspond to an integrated luminosity of 35 inverse picobarns collected by the CMS experiment at the LHC. The search is performed in events with jets and significant missing transverse energy, characteristic of the decays of heavy, pair-produced squarks and gluinos. The primary background, from standard model multijet production, is reduced by several orders of magnitude to a negligible level by the application of a set of robust kinematic requirements. With this selection, the data are consistent with the standard model backgrounds, namely t t-bar, W + jet and Z + jet production, which are estimated from data control samples. Limits are set on the parameters of the constrained minimal supersymmetric extension of the standard model. These limits extend those set previously by experiments at the Tevatron and LEP colliders.

  20. Temporal characterization of a time-compensated monochromator for high-efficiency selection of extreme-ultraviolet pulses generated by high-order harmonics

    SciTech Connect (OSTI)

    Poletto, L.; Villoresi, P.; Benedetti, E.; Ferrari, F.; Stagira, S.; Sansone, G.; Nisoli, M.

    2008-07-15

    Ultrafast extreme-ultraviolet pulses are spectrally selected by a time-delay-compensated grating monochromator. The intrinsic very short duration of the pulses is obtained by exploiting the high-order harmonic generation process. The temporal characterization of the harmonic pulses is obtained using a cross-correlation method: pulses as short as 8 fs are measured at the output of the monochromator in the case of the 23rd harmonic. This value is in agreement with the expected duration of such pulses, indicating that the influence of the monochromator is negligible. The photon flux has been measured with a calibrated photodiode, pointing out the good efficiency of the monochromator, derived by the exploitation for the two gratings of the conical diffraction mounting.

  1. An inflationary model with small scalar and large tensor nongaussianities

    SciTech Connect (OSTI)

    Cook, Jessica L.; Sorbo, Lorenzo E-mail: sorbo@physics.umass.edu

    2013-11-01

    We study a model of inflation where the scalar perturbations are almost gaussian while there is sizable (equilateral) nongaussianity in the tensor sector. In this model, a rolling pseudoscalar gravitationally coupled to the inflaton amplifies the vacuum fluctuations of a vector field. The vector sources both scalar and tensor metric perturbations. Both kinds of perturbations are nongaussian, but, due to helicity conservation, the tensors have a larger amplitude, so that nongaussianity in the scalar perturbations is negligible. Moreover, the tensors produced this way are chiral. We study, in the flat sky approximation, how constraints on tensor nongaussianities affect the detectability of parity violation in the Cosmic Microwave Background. We expect the model to feature interesting patterns on nongaussianities in the polarization spectra of the CMB.

  2. Wind load design methods for ground-based heliostats and parabolic dish collectors

    SciTech Connect (OSTI)

    Peterka, J A; Derickson, R G

    1992-09-01

    The purpose of this design method is to define wind loads on flat heliostat and parabolic dish collectors in a simplified form. Wind loads are defined for both mean and peak loads accounting for the protective influence of upwind collectors, wind protective fences, or other wind-blockage elements. The method used to define wind loads was to generalize wind load data obtained during tests on model collectors, heliostats or parabolic dishes, placed in a modeled atmospheric wind in a boundary-layer wind-tunnel at Colorado State University. For both heliostats and parabolic dishes, loads are reported for solitary collectors and for collectors as elements of a field. All collectors were solid with negligible porosity; thus the effects of porosity in the collectors is not addressed.

  3. Indirect excitation of ultrafast demagnetization

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Vodungbo, Boris; Tudu, Bahrati; Perron, Jonathan; Delaunay, Renaud; Müller, Leonard; Berntsen, Magnus H.; Grübel, Gerhard; Malinowski, Grégory; Weier, Christian; Gautier, Julien; et al

    2016-01-06

    Does the excitation of ultrafast magnetization require direct interaction between the photons of the optical pump pulse and the magnetic layer? Here, we demonstrate unambiguously that this is not the case. For this we have studied the magnetization dynamics of a ferromagnetic cobalt/palladium multilayer capped by an IR-opaque aluminum layer. Upon excitation with an intense femtosecond-short IR laser pulse, the film exhibits the classical ultrafast demagnetization phenomenon although only a negligible number of IR photons penetrate the aluminum layer. In comparison with an uncapped cobalt/palladium reference film, the initial demagnetization of the capped film occurs with a delayed onset andmore » at a slower rate. Both observations are qualitatively in line with energy transport from the aluminum layer into the underlying magnetic film by the excited, hot electrons of the aluminum film. As a result, our data thus confirm recent theoretical predictions.« less

  4. Status report on a solar photovoltaic concentrating energy system for a hospital in Hawaii

    SciTech Connect (OSTI)

    Seki, A.; Curtis, G.; Yuen, P.

    1983-06-01

    The largest parabolic concentrating photovoltaic/solar thermal system in the U.S. began producing electricity and hot water for a hospital on the island of Kauai, Hawaii in November 1981. Each of the 80 parabolic collectors is 6 feet by 10 feet and concentrates incident sunlight on photovoltaic cells mounted on two faces of the receiver at the focus. Although the 35 kilowatt system has been designed to produce 22,000 net kilowatt-hours per year of electricity and 620,000 gallons of 180 F water, electrical output (12 to 15 kilowatt-hours per day) is only 20 percent of that expected, primarily because insolation at the site has been only 40 percent of predicted values. A second problem with fungal attack on the receivers has been solved by better sealing. The system has also withstood a hurricane with negligible damage.

  5. Non-adiabatic perturbations in decaying vacuum cosmology

    SciTech Connect (OSTI)

    Zimdahl, W.; Fabris, J.C.; Borges, H.A.; Carneiro, S.; Hiplito-Ricaldi, W.S. E-mail: humberto@ufba.br E-mail: fabris@pq.cnpq.br

    2011-04-01

    We investigate a spatially flat Friedmann-Lematre-Robertson-Walker cosmology in which a decaying vacuum term causes matter production at late times. Assuming a decay proportional to the Hubble rate, the ratio of the background energy densities of dark matter and dark energy changes with the cosmic scale factor as a{sup ?3/2}. The intrinsically non-adiabatic two-component perturbation dynamics of this model is reduced to a single second-order equation. Perturbations of the vacuum term are shown to be negligible on scales that are relevant for structure formation. On larger scales, dark-energy perturbations give a somewhat higher contribution but remain always smaller than the dark-matter perturbations.

  6. X-ray photoelectron spectroscopy studies on Pd doped SnO{sub 2} liquid petroleum gas sensor

    SciTech Connect (OSTI)

    Phani, A.R.

    1997-10-01

    The present investigation deals with the electrical response of palladium doped tin oxide, as a means of improving the selectivity for liquid petroleum gas (LPG) in the presence of CO, CH{sub 4}. The sensor element with the composition of Pd(1.5 wt{percent}) in the base material SnO{sub 2} sintered at 800{degree}C, has shown a high sensitivity towards LPG with a negligible cross interference of CO and CH{sub 4} at an operating temperature of 350{degree}C. This greatly suggests the possibility of utilizing the sensor for the detection of LPG. X-ray photoelectron spectroscopy studies have been carried out to determine the possible chemical species involved in the gas-solid interaction and the enhancing mechanism of the Pd doped SnO{sub 2} sensor element, towards LPG sensitivity. {copyright} {ital 1997 American Institute of Physics.}

  7. Assessment of acreage and vegetation change in Florida`s Big Bend tidal wetlands using satellite imagery

    SciTech Connect (OSTI)

    Raabe, E.A.; Stumpf, R.P.

    1997-06-01

    Fluctuations in sea level and impending development on the west coast of Florida have aroused concern for the relatively pristine tidal marshes of the Big Bend. Landsat Thematic Mapper (TM) images for 1986 and 1995 are processed and evaluated for signs of change. The images cover 250 km of Florida`s Big Bend Gulf Coast, encompassing 160,000 acres of tidal marshes. Change is detected using the normalized difference vegetation index (NDVI) and land cover classification. The imagery shows negligible net loss or gain in the marsh over the 9-year period. However, regional changes in biomass are apparent and are due to natural disturbances such as low winter temperatures, fire, storm surge, and the conversion of forest to marsh. Within the marsh, the most prominent changes in NDVI and in land cover result from the recovery of mangroves from freezes, a decline of transitional upland vegetation, and susceptibility of the marsh edge and interior to variations in tidal flooding.

  8. Detection and imaging of the oxygen deficiency in single crystalline YBa{sub 2}Cu{sub 3}O{sub 7??} thin films using a scanning positron beam

    SciTech Connect (OSTI)

    Reiner, M.; Gigl, T.; Hugenschmidt, C.; Jany, R.; Hammerl, G.

    2015-03-16

    Single crystalline YBa{sub 2}Cu{sub 3}O{sub 7??} (YBCO) thin films were grown by pulsed laser deposition in order to probe the oxygen deficiency ? using a mono-energetic positron beam. The sample set covered a large range of ? (0.191?negligible influence of potentially present Ba or Cu vacancies to the found correlation. Moreover, scanning with the positron beam allowed us to analyze the spatial variation of ?, which was found to fluctuate with a standard deviation of up to 0.079(5) within a single YBCO film.

  9. NEW LIMITS ON GAMMA-RAY EMISSION FROM GALAXY CLUSTERS

    SciTech Connect (OSTI)

    Griffin, Rhiannon D.; Dai, Xinyu; Kochanek, Christopher S. E-mail: xdai@ou.edu

    2014-11-01

    Galaxy clusters are predicted to produce ?-rays through cosmic ray interactions and/or dark matter annihilation, potentially detectable by the Fermi Large Area Telescope (Fermi-LAT). We present a new, independent stacking analysis of Fermi-LAT photon count maps using the 78 richest nearby clusters (z < 0.12) from the Two Micron All Sky Survey cluster catalog. We obtain the lowest limit on the photon flux to date, 2.3 10{sup 11} photons cm{sup 2} s{sup 1} (95% confidence) per cluster in the 0.8-100 GeV band, which corresponds to a luminosity limit of 3.5 10{sup 44} photons s{sup 1}. We also constrain the emission limits in a range of narrower energy bands. Scaling to recent cosmic ray acceleration and ?-ray emission models, we find that cosmic rays represent a negligible contribution to the intra-cluster energy density and gas pressure.

  10. LIMB-DARKENED RADIATION-DRIVEN WINDS FROM MASSIVE STARS

    SciTech Connect (OSTI)

    Cure, M.; Cidale, L.

    2012-10-01

    We calculated the influence of the limb-darkened finite-disk correction factor in the theory of radiation-driven winds from massive stars. We solved the one-dimensional m-CAK hydrodynamical equation of rotating radiation-driven winds for all three known solutions, i.e., fast, {Omega}-slow, and {delta}-slow. We found that for the fast solution, the mass-loss rate is increased by a factor of {approx}10%, while the terminal velocity is reduced about 10%, when compared with the solution using a finite-disk correction factor from a uniformly bright star. For the other two slow solutions, the changes are almost negligible. Although we found that the limb darkening has no effects on the wind-momentum-luminosity relationship, it would affect the calculation of synthetic line profiles and the derivation of accurate wind parameters.

  11. Commissioning a passive-scattering proton therapy nozzle for accurate SOBP delivery

    SciTech Connect (OSTI)

    Engelsman, M.; Lu, H.-M.; Herrup, D.; Bussiere, M.; Kooy, H. M.

    2009-06-15

    Proton radiotherapy centers that currently use passively scattered proton beams do field specific calibrations for a non-negligible fraction of treatment fields, which is time and resource consuming. Our improved understanding of the passive scattering mode of the IBA universal nozzle, especially of the current modulation function, allowed us to re-commission our treatment control system for accurate delivery of SOBPs of any range and modulation, and to predict the output for each of these fields. We moved away from individual field calibrations to a state where continued quality assurance of SOBP field delivery is ensured by limited system-wide measurements that only require one hour per week. This manuscript reports on a protocol for generation of desired SOBPs and prediction of dose output.

  12. Nonlinear propagation of ultraintense and ultrashort laser pulses in a plasma channel limited by metallic walls

    SciTech Connect (OSTI)

    Sid, A.; Debbache, D.; Bendib, A.

    2006-08-15

    The nonlinear propagation of an ultraintense and ultrashort (UIUS) laser pulse in a metallic capillary is investigated using a classical model which takes into account the inverse bremsstrahlung absorption (IBA) in the formed plasma. The attenuation of the laser pulse due to the IBA in the plasma and to the laser energy dissipation in the metallic walls is shown. The guiding length and the twist of the laser pulse temporal envelope are presented for several values of the parameters of the plasma, the laser pulse and the metal. The numerical treatment shows that the guiding length increases when the pulse duration becomes shorter. This calculus shows also that in the case of moderate electronic densities, n{sub e}<10{sup 17} m{sup -3}, the formed plasma has a negligible effect compared to that of the metallic walls.

  13. Negative to positive magnetoresistance and magnetocaloric effect in Pr0.6Er0.4Al2

    SciTech Connect (OSTI)

    Pathak, Arjun K.; Gschneidner, Jr., K. A.; Pecharsky, V. K.

    2014-10-13

    We report on the magnetic, magnetocaloric and magnetotransport properties of Pr0.6Er0.4Al2. The title compound exhibits a large positive magnetoresistance (MR) for H ≥ 40 kOe and a small but non negligible negative MR for H ≤ 30 kOe. The maximum positive MR reaches 13% at H = 80 kOe. The magnetic entropy and adiabatic temperature changes as functions of temperature each show two anomalies: a broad dome-like maximum below 20 K and a relatively sharp peak at higher temperature. As a result, observed behaviors are unique among other binary and mixed lanthanide compounds.

  14. Lepton-mediated electroweak baryogenesis

    SciTech Connect (OSTI)

    Chung, Daniel J. H.; Garbrecht, Bjorn [University of Wisconsin, Madison, Wisconsin, 53706-1390 (United States); Ramsey-Musolf, Michael J. [University of Wisconsin, Madison, Wisconsin, 53706-1390 (United States); California Institute of Technology, Pasadena, California 91125 (United States); Tulin, Sean [California Institute of Technology, Pasadena, California 91125 (United States)

    2010-03-15

    We investigate the impact of the tau and bottom Yukawa couplings on the transport dynamics for electroweak baryogenesis in supersymmetric extensions of the standard model. Although it has generally been assumed in the literature that all Yukawa interactions except those involving the top quark are negligible, we find that the tau and bottom Yukawa interaction rates are too fast to be neglected. We identify an illustrative 'lepton-mediated electroweak baryogenesis' scenario in which the baryon asymmetry is induced mainly through the presence of a left-handed leptonic charge. We derive analytic formulas for the computation of the baryon asymmetry that, in light of these effects, are qualitatively different from those in the established literature. In this scenario, for fixed CP-violating phases, the baryon asymmetry has opposite sign compared to that calculated using established formulas.

  15. Intumescent flame retardants for polymers. I. The poly(acrylonitrile)-ammonium polyphosphate-hexabromocyclododecane system

    SciTech Connect (OSTI)

    Ballistreri, A.; Montaudo, G.; Puglisi, C.; Scamporrino, E.; Vitalini, D.

    1983-05-01

    The influence of ammonium polyphosphate (APP) and hexabromocyclododecane (HBCD) as flame retardant (FR) on poly(acrylonitrile) (PAN) has been examined. The APP-HBCD system behaves as an intumescent flame retardant (IFR) formulation, APP being the char-forming agent and HBCD the blowing agent. A negligible gas-phase mode of action was ascertained for HBCD with this substrate. A synergism between the two FR agents was observed, corresponding to about 50% increased efficacy with respect to the separate effects of the two components. Thermogravimetry (TG), oxygen index (OI), nitrous oxide index (NOI) experiments and phosphorous residue measurements were performed to substantiate the conclusion that a condensed phase mechanism of action accounts for all the facts observed.

  16. Bacillus anthracis spores germinate extracellularly at air-liquid interface in an in vitro lung model under serum-free conditions

    SciTech Connect (OSTI)

    Powell, Joshua D.; Hutchison, Janine R.; Hess, Becky M.; Straub, Tim M.

    2015-07-30

    Aims: To better understand the parameters that govern spore dissemination after lung exposure using in vitro cell systems. Methods and Results: We evaluated the kinetics of uptake, germination and proliferation of B. anthracis Sterne spores in association with human primary lung epithelial cells, Calu-3, and A549 cell lines. We also analyzed the influence of various cell culture media formulations related to spore germination. Conclusions: We found negligible spore uptake by epithelial cells, but germination and proliferation of spores in the extracellular environment was evident, and was appreciably higher in A549 and Calu-3 cultures than in primary epithelial cells. Additionally, our results revealed spores in association with primary cells submerged in cell culture media germinated 1 h

  17. Surrogate Guderley Test Problem Definition

    SciTech Connect (OSTI)

    Ramsey, Scott D.; Shashkov, Mikhail J.

    2012-07-06

    The surrogate Guderley problem (SGP) is a 'spherical shock tube' (or 'spherical driven implosion') designed to ease the notoriously subtle initialization of the true Guderley problem, while still maintaining a high degree of fidelity. In this problem (similar to the Guderley problem), an infinitely strong shock wave forms and converges in one-dimensional (1D) cylindrical or spherical symmetry through a polytropic gas with arbitrary adiabatic index {gamma}, uniform density {rho}{sub 0}, zero velocity, and negligible pre-shock pressure and specific internal energy (SIE). This shock proceeds to focus on the point or axis of symmetry at r = 0 (resulting in ostensibly infinite pressure, velocity, etc.) and reflect back out into the incoming perturbed gas.

  18. The beaming pattern of external Compton emission from relativistic outflows: The case of anisotropic distribution of electrons

    SciTech Connect (OSTI)

    Kelner, S. R.; Lefa, E.; Rieger, F. M.; Aharonian, F. A.

    2014-04-20

    The beaming pattern of radiation emitted by a relativistically moving source, such as jets in microquasars, active galactic nuclei, and gamma-ray bursts, is a key issue for understanding acceleration and radiation processes in these objects. In this paper, we introduce a formalism based on a solution of the photon transfer equation to study the beaming patterns for emission produced by electrons accelerated in the jet and the upscattering photons of low-energy radiation fields of external origin (the so-called external Compton scenario). The formalism allows us to treat non-stationary, non-homogeneous, and anisotropic distributions of electrons, but assuming homogeneous/isotropic and non-variable target photon fields. We demonstrate the non-negligible impact of the anisotropy in the electron distribution on angular and spectral characteristics of the EC radiation.

  19. Dominance of interface chemistry over the bulk properties in determining the electronic structure of epitaxial metal/perovskite oxide heterojunctions

    SciTech Connect (OSTI)

    Chambers, Scott A.; Du, Yingge; Gu, Meng; Droubay, Timothy C.; Hepplestone, Steven; Sushko, Petr

    2015-06-09

    We show that despite very similar crystallographic properties and work function values in the bulk, epitaxial Fe and Cr metallizations on Nb:SrTiO3(001) generate completely different heterojunction electronic properties. Cr is Ohmic whereas Fe forms a Schottky barrier with a barrier height of 0.50 eV. This contrast arises because of differences in interface chemistry. In contrast to Cr [Chambers, S. A. et al., Adv. Mater. 2013, 25, 4001.], Fe exhibits a +2 oxidation state and occupies Ti sites in the perovskite lattice, resulting in negligible charge transfer to Ti, upward band bending, and Schottky barrier formation. The differences between Cr and Fe are understood by performing first-principles calculations of the energetics of defect formation which corroborate the observed interface chemistry and structure.

  20. Cr.sup.3+ -doped colquiriite solid state laser material

    DOE Patents [OSTI]

    Payne, Stephen A. (Castro Valley, CA); Chase, Lloyd L. (Livermore, CA); Newkirk, Herbert W. (Livermore, CA); Krupke, William F. (Pleasanton, CA)

    1989-01-01

    Chromium doped colquiriite, LiCaAlF.sub.6 :Cr.sup.3+, is useful as a tunable laser crystal that has a high intrinsic slope efficiency, comparable to or exceeding that of alexandrite, the current leading performer of vibronic sideband Cr.sup.3+ lasers. The laser output is tunable from at least 720 nm to 840 nm with a measured slop efficiency of about 60% in a Kr laser pumped laser configuration. The intrinsic slope efficiency (in the limit of large output coupling) may approach the quantum defect limited value of 83%. The high slope efficiency implies that excited state absorption (ESA) is negligible. The potential for efficiency and the tuning range of this material satisfy the requirements for a pump laser for a high density storage medium incorporating Nd.sup.3+ or Tm.sup.3+ for use in a multimegajoule single shot fusion research facility.

  1. Environmental Impacts, Health and Safety Impacts, and Financial Costs of the Front End of the Nuclear Fuel Cycle

    SciTech Connect (OSTI)

    Brett W Carlsen; Urairisa Phathanapirom; Eric Schneider; John S. Collins; Roderick G. Eggert; Brett Jordan; Bethany L. Smith; Timothy M. Ault; Alan G. Croff; Steven L. Krahn; William G. Halsey; Mark Sutton; Clay E. Easterly; Ryan P. Manger; C. Wilson McGinn; Stephen E. Fisher; Brent W. Dixon; Latif Yacout

    2013-07-01

    FEFC processes, unlike many of the proposed fuel cycles and technologies under consideration, involve mature operational processes presently in use at a number of facilities worldwide. This report identifies significant impacts resulting from these current FEFC processes and activities. Impacts considered to be significant are those that may be helpful in differentiating between fuel cycle performance and for which the FEFC impact is not negligible relative to those from the remainder of the full fuel cycle. This report: • Defines ‘representative’ processes that typify impacts associated with each step of the FEFC, • Establishes a framework and architecture for rolling up impacts into normalized measures that can be scaled to quantify their contribution to the total impacts associated with various fuel cycles, and • Develops and documents the bases for estimates of the impacts and costs associated with each of the representative FEFC processes.

  2. Molten uranium dioxide structure and dynamics

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Skinner, L. B.; Parise, J. B.; Benmore, C. J.; Weber, J. K.R.; Williamson, M. A.; Tamalonis, A.; Hebden, A.; Wiencek, T.; Alderman, O. L.G.; Guthrie, M.; et al

    2014-11-21

    Uranium dioxide (UO2) is the major nuclear fuel component of fission power reactors. A key concern during severe accidents is the melting and leakage of radioactive UO2 as it corrodes through its zirconium cladding and steel containment. Yet, the very high temperatures (>3140 kelvin) and chemical reactivity of molten UO2 have prevented structural studies. In this work, we combine laser heating, sample levitation, and synchrotron x-rays to obtain pair distribution function measurements of hot solid and molten UO2. The hot solid shows a substantial increase in oxygen disorder around the lambda transition (2670 K) but negligible U-O coordination change. Onmore » melting, the average U-O coordination drops from 8 to 6.7 ± 0.5. Molecular dynamics models refined to this structure predict higher U-U mobility than 8-coordinated melts.« less

  3. FULLY CONVECTIVE MAGNETOROTATIONAL TURBULENCE IN STRATIFIED SHEARING BOXES

    SciTech Connect (OSTI)

    Bodo, G.; Rossi, P.; Cattaneo, F.; Mignone, A.

    2013-07-10

    We present a numerical study of turbulence and dynamo action in stratified shearing boxes with zero magnetic flux. We assume that the fluid obeys the perfect gas law and has finite (constant) thermal diffusivity. We choose radiative boundary conditions at the vertical boundaries in which the heat flux is proportional to the fourth power of the temperature. We compare the results with the corresponding cases in which fixed temperature boundary conditions are applied. The most notable result is that the formation of a fully convective state in which the density is nearly constant as a function of height and the heat is transported to the upper and lower boundaries by overturning motions is robust and persists even in cases with radiative boundary conditions. Interestingly, in the convective regime, although the diffusive transport is negligible, the mean stratification does not relax to an adiabatic state.

  4. Emulation to simulate low resolution atmospheric data

    SciTech Connect (OSTI)

    Hebbur Venkata Subba Rao, Vishwas [ORNL; Archibald, Richard K [ORNL; Evans, Katherine J [ORNL

    2012-08-01

    Climate simulations require significant compute power, they are complex and therefore it is time consuming to simulate them. We have developed an emulator to simulate unknown climate datasets. The emulator uses stochastic collocation and multi-dimensional in- terpolation to simulate the datasets. We have used the emulator to determine various physical quantities such as temperature, short and long wave cloud forcing, zonal winds etc. The emulation gives results which are very close to those obtained by simulations. The emulator was tested on 2 degree atmospheric datasets. The work evaluates the pros and cons of evaluating the mean first and inter- polating and vice versa. To determine the physical quantities, we have assumed them to be a function of time, longitude, latitude and a random parameter. We have looked at parameters that govern high stable clouds, low stable clouds, timescale for convection etc. The emulator is especially useful as it requires negligible compute times when compared to the simulation itself.

  5. GHz laser-free time-resolved transmission electron microscopy: A stroboscopic high-duty-cycle method

    SciTech Connect (OSTI)

    Qiu, Jiaqi; Zhu, Yimei; Ha, Gwanghui; Jing, Chunguang; Baryshev, Sergey V.; Reed, Bryan W.; Lau, June W.

    2015-11-10

    In this study, a device and a method for producing ultrashort electron pulses with GHz repetition rates via pulsing an input direct current (dc) electron beam are provided. The device and the method are based on an electromagnetic-mechanical pulser (EMMP) that consists of a series of transverse deflecting cavities and magnetic quadrupoles. The EMMP modulates and chops the incoming dc electron beam and converts it into pico- and sub-pico-second electron pulse sequences (pulse trains) at >1 GHz repetition rates, as well as controllably manipulates the resulting pulses. Ultimately, it leads to negligible electron pulse phase-space degradation compared to the incoming dc beam parameters. The temporal pulse length and repetition rate for the EMMP can be continuously tunable over wide ranges.

  6. Apparatus and method for polarizing polarizable nuclear species

    DOE Patents [OSTI]

    Hersman, F. William; Leuschner, Mark; Carberry, Jeannette

    2005-09-27

    The present invention is a polarizing process involving a number of steps. The first step requires moving a flowing mixture of gas, the gas at least containing a polarizable nuclear species and vapor of at least one alkali metal, with a transport velocity that is not negligible when compared with the natural velocity of diffusive transport. The second step is propagating laser light in a direction, preferably at least partially through a polarizing cell. The next step is directing the flowing gas along a direction generally opposite to the direction of laser light propagating. The next step is containing the flowing gas mixture in the polarizing cell. The final step is immersing the polarizing cell in a magnetic field. These steps can be initiated in any order, although the flowing gas, the propagating laser and the magnetic field immersion must be concurrently active for polarization to occur.

  7. Enhanced optoelectronic quality of perovskite thin films with hypophosphorous acid for planar heterojunction solar cells

    SciTech Connect (OSTI)

    Zhang, Wei; Pathak, Sandeep; Sakai, Nobuya; Stergiopoulos, Thomas; Nayak, Pabitra K.; Noel, Nakita K.; Haghighirad, Amir A.; Burlakov, Victor M.; deQuilettes, Dane W.; Sadhanala, Aditya; Li, Wenzhe; Wang, Liduo; Ginger, David S.; Friend, Richard H.; Snaith, Henry J.

    2015-11-30

    Solution-processed metal halide perovskite semiconductors, such as CH3NH3PbI3, have exhibited remarkable performance in solar cells, despite having non-negligible density of defect states. A likely candidate is halide vacancies within the perovskite crystals, or the presence of metallic lead, both generated due to the imbalanced I/Pb stoichiometry which could evolve during crystallization. Herein, we show that the addition of hypophosphorous acid (HPA) in the precursor solution can significantly improve the film quality, both electronically and topologically, and enhance the photoluminescence intensity, which leads to more efficient and reproducible photovoltaic devices. We demonstrate that the HPA can reduce the oxidized I2 back into I-, and our results indicate that this facilitates an improved stoichiometry in the perovskite crystal and a reduced density of metallic lead.

  8. A novel design for monolithic interconnected modules (MIMs) for thermophotovoltaic (TPV) power conversion

    SciTech Connect (OSTI)

    Ward, J.S.; Duda, A.; Wanlass, M.W.

    1997-06-01

    The design for the fabrication of Monolithic Interconnected Modules (MIMs) for thermophotovoltaic (TPV) power conversion described in this paper utilizes a novel, interdigitated contacting scheme that increases the flexibility in the size of the component cells and hence the output current and voltage of the module. This flexibility is gained at the expense of only minimally increased grid obscuration. Because the design uses the grid fingers of the component cells as the interconnect structure, the area of the device used for this purpose becomes negligible. In this paper the authors report on the specifics of the design as well as issues related to the fabrication of the modules. Preliminary performance data for representative modules also are offered.

  9. Energetics of runaway electrons during tokamak disruptions

    SciTech Connect (OSTI)

    Riemann, J.; Helander, P.; Smith, H. M.

    2012-01-15

    In a tokamak disruption, a substantial fraction of the plasma current can be converted into runaway electrons. Although these are usually highly relativistic, their total energy is initially much smaller than that of the pre-disruption plasma. However, following a suggestion by Putvinski et al.[Plasma Phys. Controlled Fusion 39, B157 (1997)], it is shown that as the post-disruption plasma drifts toward the first wall, a non-negligible part of the energy contained in the poloidal magnetic field can be converted into kinetic energy of the runaway electrons. This process is simulated numerically, and it is found that in an ITER-like tokamak runaway electrons can gain kinetic energies up to about 70 MJ by this mechanism.

  10. Sagittal focusing of synchrotron x radiation with curved crystals

    SciTech Connect (OSTI)

    Sparks, C.J. Jr.; Ice, G.E.; Wong, J.; Batterman, B.W.

    1981-01-01

    We describe the sagittal focusing of x rays with singly bent crystals that accept the meridian plane divergence from a similar but flat crystal to form a pair in a nondispersive two-crystal Bragg monochromator. Curved crystals can intercept from 5 to 20 times the sagittal divergence of curved mirrors at x-ray energies above 10 keV. Anticlastic (transverse) bending of the crystal is made negligible in the meridian plane with reinforcing ribs cut parallel to the plane of scattering. Results show that at energies of 10, 20, and 30 keV the bent crystal performs efficiently and images the source size at the Cornell High Energy Synchrotron Source.

  11. Influence of Li ions on the oxygen reduction reaction of platinum electrocatalyst

    SciTech Connect (OSTI)

    Liu, H; Xing, YC

    2011-06-01

    A Li-air battery can provide a much higher theoretical energy density than a Li-ion battery. The use of aqueous acidic electrolytes may prevent lithium oxide deposition from aprotic electrolytes and lithium carbonate precipitation from alkaline electrolytes. The present communication reports a study on the effect of Li ions on the oxygen reduction reaction (ORR) in sulfuric acid electrolytes. It was found that the Li ions have negligible interactions with the active surface of Pt catalysts. However, significantly lower ORR activities were found when Li ions are present in the sulfuric acid. The intrinsic kinetic activities were found to decrease with the increase of Li ion concentrations, but level off when the Li ion concentrations are larger than 1.0 M. The low activities of Pt catalysts in Li ion containing electrolytes were attributed to a constraining effect of Li ions on the diffusion of oxygen in the electrolyte solution. (C) 2011 Elsevier B.V. All rights reserved.

  12. Investigation of Wave Energy Converter Effects on the Nearshore Environment: A Month-Long Study in Monterey Bay CA.

    SciTech Connect (OSTI)

    Roberts, Jesse D.; Chang, Grace; Magalen, Jason; Jones, Craig

    2014-09-01

    A modified version of an indust ry standard wave modeling tool, SNL - SWAN, was used to perform model simulations for hourly initial wave conditio ns measured during the month of October 2009. The model was run with an array of 50 wave energy converters (WECs) and compared with model runs without WECs. Maximum changes in H s were found in the lee of the WEC array along the angles of incident wave dire ction and minimal changes were found along the western side of the model domain due to wave shadowing by land. The largest wave height reductions occurred during observed typhoon conditions and resulted in 14% decreases in H s along the Santa Cruz shoreline . Shoreline reductions in H s were 5% during s outh swell wave conditions and negligible during average monthly wave conditions.

  13. Investigation of Wave Energy Converter Effects on Wave Fields: A Modeling Sensitivity Study in Monterey Bay CA.

    SciTech Connect (OSTI)

    Roberts, Jesse D.; Grace Chang; Jason Magalen; Craig Jones

    2014-08-01

    A n indust ry standard wave modeling tool was utilized to investigate model sensitivity to input parameters and wave energy converter ( WEC ) array deploym ent scenarios. Wave propagation was investigated d ownstream of the WECs to evaluate overall near - and far - field effects of WEC arrays. The sensitivity study illustrate d that b oth wave height and near - bottom orbital velocity we re subject to the largest pote ntial variations, each decreas ed in sensitivity as transmission coefficient increase d , as number and spacing of WEC devices decrease d , and as the deployment location move d offshore. Wave direction wa s affected consistently for all parameters and wave perio d was not affected (or negligibly affected) by varying model parameters or WEC configuration .

  14. Magnetization plateaus of dipolar spin ice on kagome lattice

    SciTech Connect (OSTI)

    Xie, Y. L.; Wang, Y. L.; Yan, Z. B.; Liu, J.-M.

    2014-05-07

    Unlike spin ice on pyrochlore lattice, the spin ice structure on kagome lattice retains net magnetic charge, indicating non-negligible dipolar interaction in modulating the spin ice states. While it is predicted that the dipolar spin ice on kagome lattice exhibits a ground state with magnetic charge order and ?3???3 spin order, our work focuses on the magnetization plateau of this system. By employing the Wang-Landau algorithm, it is revealed that the lattice exhibits the fantastic three-step magnetization in response to magnetic field h along the [10] and [01] directions, respectively. For the h//[1 0] case, an additional ?3/6M{sub s} step, where M{sub s} is the saturated magnetization, is observed in a specific temperature range, corresponding to a new state with charge order and short-range spin order.

  15. Half-metallic ferromagnetism in Cr-doped semiconducting Ge-chalcogenide: Density functional approach

    SciTech Connect (OSTI)

    Saini, Hardev S.; Singh, Mukhtiyar; Thakur, Jyoti; Kashyap, Manish K.

    2014-04-24

    A supercell approach has been used to calculate the electronic and magnetic properties of Cr-doped Ge chalcogenide, Ge{sub 1−x}Cr{sub x}Te (x = 0.25 and 0.125). The calculations have been performed using full potential Linear Augmented Plane Wave (FPLAPW) method within generalized gradient approximation (GGA) as exchange-correlation (XC) potential. The calculated results show that the doping of Cr induces the 100% spin polarization at Fermi level (EF) and showed the robust half metallic ferromagnetism in this compound. Thus, the compound at both dopant concentrations behave as dilute magnetic semiconductor (DMS) showing metallic property in majority and semiconducting for minority spin channels which is best suited for spintronic applications. The total magnetic moments of this compound are mainly due to Cr-d states present at E{sup F} with negligible contribution from electronic states of other atoms.

  16. Robustness of n-GaAs carrier spin properties to 5 MeV proton irradiation

    SciTech Connect (OSTI)

    Pursley, Brennan C.; Song, X.; Torres-Isea, R. O.; Bokari, E. A.; Kayani, A.; Sih, V.

    2015-02-16

    Modern electronic devices utilize charge to transmit and store information. This leaves the information susceptible to external influences, such as radiation, that can introduce short timescale charge fluctuations and, long term, degrade electronic properties. Encoding information as spin polarizations offers an attractive alternative to electronic logic that should be robust to randomly polarized transient radiation effects. As a preliminary step towards radiation-resistant spintronic devices, we measure the spin properties of n-GaAs as a function of radiation fluence using time-resolved Kerr rotation and photoluminescence spectroscopy. Our results show a modest to negligible change in the long-term electron spin properties up to a fluence of 1 × 10{sup 14} (5 MeV protons)/cm{sup 2}, even as the luminescence decreases by two orders of magnitude.

  17. Analytical and computational study of the ideal full two-fluid plasma model and asymptotic approximations for Hall-magnetohydrodynamics

    SciTech Connect (OSTI)

    Srinivasan, B.; Shumlak, U.

    2011-09-15

    The 5-moment two-fluid plasma model uses Euler equations to describe the ion and electron fluids and Maxwell's equations to describe the electric and magnetic fields. Two-fluid physics becomes significant when the characteristic spatial scales are on the order of the ion skin depth and characteristic time scales are on the order of the ion cyclotron period. The full two-fluid plasma model has disparate characteristic speeds ranging from the ion and electron speeds of sound to the speed of light. Two asymptotic approximations are applied to the full two-fluid plasma to arrive at the Hall-MHD model, namely negligible electron inertia and infinite speed of light. The full two-fluid plasma model and the Hall-MHD model are studied for applications to an electromagnetic plasma shock, geospace environmental modeling (GEM challenge) magnetic reconnection, an axisymmetric Z-pinch, and an axisymmetric field reversed configuration (FRC).

  18. Particle-in-cell/accelerator code for space-charge dominated beam simulation

    Energy Science and Technology Software Center (OSTI)

    2012-05-08

    Warp is a multidimensional discrete-particle beam simulation program designed to be applicable where the beam space-charge is non-negligible or dominant. It is being developed in a collaboration among LLNL, LBNL and the University of Maryland. It was originally designed and optimized for heave ion fusion accelerator physics studies, but has received use in a broader range of applications, including for example laser wakefield accelerators, e-cloud studies in high enery accelerators, particle traps and other areas.more » At present it incorporates 3-D, axisymmetric (r,z) planar (x-z) and transverse slice (x,y) descriptions, with both electrostatic and electro-magnetic fields, and a beam envelope model. The code is guilt atop the Python interpreter language.« less

  19. Structural modifications due to interface chemistry at metal-nitride interfaces

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yadav, S. K.; Shao, S.; Wang, J.; Liu, X. -Y.

    2015-11-27

    Based on accurate first principles density functional theory (DFT) calculations, an unusual phenomenon of interfacial structural modifications, due to the interface chemistry influence is identified at two metal-nitride interfaces with strong metal-nitrogen affinity, Al/TiN {111} and Al/VN {111} interfaces. It is shown that at such interfaces, a faulted stacking structure is energetically preferred on the Al side of the interface. And both intrinsic and extrinsic stacking fault energies in the vicinity Al layers are negligibly small. However, such phenomenon does not occur in Pt/TiN and Pt/VN interfaces because of the weak Pt-N affinity. As a result, corresponding to structural energiesmore » of metal-nitride interfaces, the linear elasticity analysis predicts characteristics of interfacial misfit dislocations at metal-nitride interfaces.« less

  20. Electron heating due to microwave photoexcitation in the high mobility GaAs/AlGaAs two dimensional electron system

    SciTech Connect (OSTI)

    Ramanayaka, A. N.; Mani, R. G.; Wegscheider, W.

    2013-12-04

    We extract the electron temperature in the microwave photo-excited high mobility GaAs/AlGaAs two dimensional electron system (2DES) by studying the influence of microwave radiation on the amplitude of Shubnikov-de Haas oscillations (SdHOs) in a regime where the cyclotron frequency, ?{sub c}, and the microwave angular frequency, ?, satisfy 2? ? ?{sub c} ? 3.5? The results indicate that increasing the incident microwave power has a weak effect on the amplitude of the SdHOs and therefore the electron temperature, in comparison to the influence of modest temperature changes on the dark-specimen SdH effect. The results indicate negligible electron heating under modest microwave photo-excitation, in good agreement with theoretical predictions.

  1. Uncertainty Analysis for Photovoltaic Degradation Rates (Poster)

    SciTech Connect (OSTI)

    Jordan, D.; Kurtz, S.; Hansen, C.

    2014-04-01

    Dependable and predictable energy production is the key to the long-term success of the PV industry. PV systems show over the lifetime of their exposure a gradual decline that depends on many different factors such as module technology, module type, mounting configuration, climate etc. When degradation rates are determined from continuous data the statistical uncertainty is easily calculated from the regression coefficients. However, total uncertainty that includes measurement uncertainty and instrumentation drift is far more difficult to determine. A Monte Carlo simulation approach was chosen to investigate a comprehensive uncertainty analysis. The most important effect for degradation rates is to avoid instrumentation that changes over time in the field. For instance, a drifting irradiance sensor, which can be achieved through regular calibration, can lead to a substantially erroneous degradation rates. However, the accuracy of the irradiance sensor has negligible impact on degradation rate uncertainty emphasizing that precision (relative accuracy) is more important than absolute accuracy.

  2. Synergy between pair coupled cluster doubles and pair density functional theory

    SciTech Connect (OSTI)

    Garza, Alejandro J.; Bulik, Ireneusz W.; Henderson, Thomas M.; Scuseria, Gustavo E.

    2015-01-28

    Pair coupled cluster doubles (pCCD) has been recently studied as a method capable of accounting for static correlation with low polynomial cost. We present three combinations of pCCD with KohnSham functionals of the density and on-top pair density (the probability of finding two electrons on top of each other) to add dynamic correlation to pCCD without double counting. With a negligible increase in computational cost, these pCCD+DFT blends greatly improve upon pCCD in the description of typical problems where static and dynamic correlations are both important. We argue thatas a black-box method with low scaling, size-extensivity, size-consistency, and a simple quasidiagonal two-particle density matrixpCCD is an excellent match for pair density functionals in this type of fusion of multireference wavefunctions with DFT.

  3. Collisionless damping of circularly polarized nonlinear Alfvn waves in solar wind plasmas with and without beam protons

    SciTech Connect (OSTI)

    Nariyuki, Y.; Hada, T.; Tsubouchi, K.

    2014-10-01

    The damping process of field-aligned, low-frequency right-handed polarized nonlinear Alfvn waves (NAWs) in solar wind plasmas with and without proton beams is studied by using a two-dimensional ion hybrid code. The numerical results show that the obliquely propagating kinetic Alfvn waves (KAWs) excited by beam protons affect the damping of the low-frequency NAW in low beta plasmas, while the nonlinear wave-wave interaction between parallel propagating waves and nonlinear Landau damping due to the envelope modulation are the dominant damping process in high beta plasmas. The nonlinear interaction between the NAWs and KAWs does not cause effective energy transfer to the perpendicular direction. Numerical results suggest that while the collisionless damping due to the compressibility of the envelope-modulated NAW plays an important role in the damping of the field-aligned NAW, the effect of the beam instabilities may not be negligible in low beta solar wind plasmas.

  4. Bacillus anthracis spores germinate extracellularly at air-liquid interface in an in vitro lung model under serum-free conditions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Powell, Joshua D.; Hutchison, Janine R.; Hess, Becky M.; Straub, Tim M.

    2015-07-30

    Aims: To better understand the parameters that govern spore dissemination after lung exposure using in vitro cell systems. Methods and Results: We evaluated the kinetics of uptake, germination and proliferation of B. anthracis Sterne spores in association with human primary lung epithelial cells, Calu-3, and A549 cell lines. We also analyzed the influence of various cell culture media formulations related to spore germination. Conclusions: We found negligible spore uptake by epithelial cells, but germination and proliferation of spores in the extracellular environment was evident, and was appreciably higher in A549 and Calu-3 cultures than in primary epithelial cells. Additionally, ourmore » results revealed spores in association with primary cells submerged in cell culture media germinated 1 h« less

  5. Line-focus solar central power system, phase I. Subsystem experiment: receiver heat transfer

    SciTech Connect (OSTI)

    Slemmons, A J

    1980-04-01

    Wind-tunnel tests confirmed that heat losses due to natural convection are negligible in the line-focus, solar-powered receiver. Anomalies in the forced-convection tests prevented definitive conclusions regarding the more important forced convection. Flow-visualization tests using a water table show much lower velocities inside the receiver cavity than outside, supporting the supposition that the forced-heat transfer should be less than that from a standard exposed cylinder. Furthermore, the water-table tests showed ways to decrease the low velocities in the cavity should this be desired. Further wind-tunnel testing should be done to confirm estimates and to support advanced design. This testing can be done in standard wind tunnels since only the forced convection is of concern.

  6. The Dependence of the Oxidation Enhancement of InP(100) Surface on the Coverage of the Adsorbed Cs

    SciTech Connect (OSTI)

    Sun, Yun

    2010-06-07

    We report the oxidation of the InP(100) surface promoted by adsorbed Cs by synchrotron radiation photoemission. Oxygen exposure causes reduction of the charge transferred to the InP substrate from Cs and the growth of indium oxide and phosphorous oxide. The oxide growth displays a clear dependence on the Cs coverage. The oxidation of phosphorous is negligible up to 1000 L of O{sub 2} exposure when the Cs coverage is less than half a monolayer (ML), but the formation of the second half monolayer of Cs greatly accelerates the oxidation. This different enhancement of the InP oxidation by the first and the second half monolayer of Cs is due to the double layer structure of the adsorbed Cs atoms, and consequently the higher 6s electron density in the Cs atoms when Cs coverage is larger than 0.5 ML.

  7. Simulation of Electric Field in Semi Insulating Au/CdTe/Au Detector under Flux

    SciTech Connect (OSTI)

    Franc, J.; James, R.; Grill, R.; Kubat, J.; Belas, E.; Hoschl, P.; Moravec, P.; Praus, P.

    2009-08-02

    We report our simulations on the profile of the electric field in semi insulating CdTe and CdZnTe with Au contacts under radiation flux. The type of the space charge and electric field distribution in the Au/CdTe/Au structure is at high fluxes result of a combined influence of charge formed due to band bending at the electrodes and from photo generated carriers, which are trapped at deep levels. Simultaneous solution of drift-diffusion and Poisson equations is used for the calculation. We show, that the space charge originating from trapped photo-carriers starts to dominate at fluxes 10{sup 15}-10{sup 16}cm{sup -2}s{sup -1}, when the influence of contacts starts to be negligible.

  8. Ultraviolet Absorption Spectrum of Malonaldehyde in Water Is Dominated by Solvent-Stabilized Conformations

    SciTech Connect (OSTI)

    Xu, Xuefei; Zheng, Jingjing; Truhlar, Donald G.

    2015-07-01

    Free energy calculations for eight enol isomers of malonaldehyde (MA) and simulation of the ultraviolet (UV) absorption spectrum in both the gas phase and water (pH = 3, where the molecule exists in neutral undeprotonated form) show that in water the two s-trans nonchelated enol conformers of MA become thermodynamically more stable than the internally hydrogen-bonded (chelated enol) conformer (CE). The pure CE conformer in water has a slightly red-shifted UV spectrum with respect to that in the gas phase, but the blue-shifted spectrum observed in water at pH 3 is dominated by solvent-stabilized conformations that have negligible populations in the gas phase. Density functional calculations with the solvation model based on density (SMD) and an ensemble-averaged vertical excitation model explain the experimental observations in detail.

  9. Image intensifier gain uniformity improvements in sealed tubes by selective scrubbing

    DOE Patents [OSTI]

    Thomas, Stanley W. (Livermore, CA)

    1995-01-01

    The gain uniformity of sealed microchannel plate image intensifiers (MCPIs) is improved by selectively scrubbing the high gain sections with a controlled bright light source. Using the premise that ions returning to the cathode from the microchannel plate (MCP) damage the cathode and reduce its sensitivity, a HeNe laser beam light source is raster scanned across the cathode of a microchannel plate image intensifier (MCPI) tube. Cathode current is monitored and when it exceeds a preset threshold, the sweep rate is decreased 1000 times, giving 1000 times the exposure to cathode areas with sensitivity greater than the threshold. The threshold is set at the cathode current corresponding to the lowest sensitivity in the active cathode area so that sensitivity of the entire cathode is reduced to this level. This process reduces tube gain by between 10% and 30% in the high gain areas while gain reduction in low gain areas is negligible.

  10. Analysis of core damage frequency due to external events at the DOE (Department of Energy) N-Reactor

    SciTech Connect (OSTI)

    Lambright, J.A.; Bohn, M.P.; Daniel, S.L. ); Baxter, J.T. ); Johnson, J.J.; Ravindra, M.K.; Hashimoto, P.O.; Mraz, M.J.; Tong, W.H.; Conoscente, J.P. ); Brosseau, D.A. )

    1990-11-01

    A complete external events probabilistic risk assessment has been performed for the N-Reactor power plant, making full use of all insights gained during the past ten years' developments in risk assessment methodologies. A detailed screening analysis was performed which showed that all external events had negligible contribution to core damage frequency except fires, seismic events, and external flooding. A limited scope analysis of the external flooding risk indicated that it is not a major risk contributor. Detailed analyses of the fire and seismic risks resulted in total (mean) core damage frequencies of 1.96E-5 and 4.60E-05 per reactor year, respectively. Detailed uncertainty analyses were performed for both fire and seismic risks. These results show that the core damage frequency profile for these events is comparable to that found for existing commercial power plants if proposed fixes are completed as part of the restart program. 108 refs., 85 figs., 80 tabs.

  11. Particle Image Velocimetry Measurements and Analysis of Bypass Data for a Scaled 6mm Gap

    SciTech Connect (OSTI)

    J.R. Wolf; T.E. Conder; R.R. Schultz

    2012-09-01

    The purpose of the fluid dynamics experiments in the MIR (Matched Index of-Refraction) flow system at Idaho National Laboratory (INL) is to develop benchmark databases for the assessment of Computational Fluid Dynamics (CFD) solutions of the momentum equations, scalar mixing, and turbulence models for the flow ratios between coolant channels and bypass gaps in the interstitial regions of typical prismatic standard fuel element (SFE) or upper reflector block geometries of typical Modular High-temperature Gas-cooled Reactors (MHTGR) in the limiting case of negligible buoyancy and constant fluid properties. The experiments will use optical techniques, primarily particle image velocimetry (PIV) in the INL Matched Index of Refraction (MIR) flow system.

  12. Accelerated high-temperature tests with spent PWR and BWR fuel rods under dry storage conditions

    SciTech Connect (OSTI)

    Porsch, G.; Fleisch, J.; Heits, B.

    1986-09-01

    Accelerated high-temperature tests on 25 intact pressurized water and boiling water reactor rods were conducted for more than 16 months at 400, 430, and 450/sup 0/C in a helium gas atmosphere. The pretest characterized rods were examined by nondestructive methods after each of the three test cycles. No cladding breaches occurred and the creep deformation remained below 1%, which was in good agreement with model calculations. The test atmospheres were analyzed for /sup 85/Kr and tritium. The /sup 85/Kr concentrations were negligible and the tritium release agreed with the theoretical predictions. It can be concluded that for Zircaloy-clad fuel, cladding temperatures up to 450/sup 0/C are acceptable for dry storage in inert cover gases.

  13. Study of surface morphology and alignment of MWCNTs grown by chemical vapor deposition

    SciTech Connect (OSTI)

    Shukrullah, S. E-mail: noranimuti-mohamed@petronas.com.my Mohamed, N. M. E-mail: noranimuti-mohamed@petronas.com.my Shaharun, M. S. E-mail: noranimuti-mohamed@petronas.com.my; Yasar, M.

    2014-10-24

    In this research work, Multiwalled Carbon Nanotubes (MWCNTs) have been synthesized successfully by using floating catalytic chemical vapor deposition (FCCVD) method. Different ferrocene amounts (0.1, 0.125 and 0.15 g) were used as catalyst and ethylene was used as a carbon precursor at reaction temperature of 800C. Characterization of the grown MWCNTs was carried out by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The obtained data showed that the catalyst weight affects the nanotubes diameter, alignment, crystallinity and growth significantly, whereas negligible influence was noticed on CNTs forest length. The dense, uniform and meadow like patterns of grown CNTs were observed for 0.15 g ferrocene. The average diameter of the grown CNTs was found in the range of 32 to 75 nm. Close inspection of the TEM images also confirmed the defects in some of the grown CNTs, where few black spots were evident in CNTs structure.

  14. Giant magnetoelastic distortions of the crystal structure of the weakly anisotropic compound UFe/sub 2/

    SciTech Connect (OSTI)

    Popov, Y.F.; Levitin, R.Z.; Zeleny, M.; Deryagin, A.V.; Andreev, A.V.

    1980-06-01

    We investigate the temperature dependences of the crystal-lattice parameters, of the anisotropy, and of the Young's modulus of the intermetallide compound UFe/sub 2/. The contribution of the uranium ions to the magnetic moment of this compound is negligible (..mu../sub U/=0.06..mu../sub B/), owing to the almoft complete delocalization of the uranium 5f electrons. The measured magnetic anisotropy is relatively small (K/sub 1/approx. =-10/sup 6/ erg/cm/sup 3/ at 0 K). However, the transition to the magnetically ordered state (T/sub c/=170 K) is accompanied by large rhombohedral distortions of the UFe/sub 2/ crystal structure and by a considerable anomaly of the Young's modulus, thus attesting to a large value of the magnetoelastic interaction in this compound (..delta..K/sub 1/ /sup m/eapprox. =-8 x 10/sup 6/ erg/cm/sup 3/).

  15. On the minimum dark matter mass testable by neutrinos from the Sun

    SciTech Connect (OSTI)

    Busoni, Giorgio; Simone, Andrea De; Huang, Wei-Chih E-mail: andrea.desimone@sissa.it

    2013-07-01

    We discuss a limitation on extracting bounds on the scattering cross section of dark matter with nucleons, using neutrinos from the Sun. If the dark matter particle is sufficiently light (less than about 4 GeV), the effect of evaporation is not negligible and the capture process goes in equilibrium with the evaporation. In this regime, the flux of solar neutrinos of dark matter origin becomes independent of the scattering cross section and therefore no constraint can be placed on it. We find the minimum values of dark matter masses for which the scattering cross section on nucleons can be probed using neutrinos from the Sun. We also provide simple and accurate fitting functions for all the relevant processes of GeV-scale dark matter in the Sun.

  16. Magnetic anisotropies in epitaxial Fe{sub 3}O{sub 4}/GaAs(100) patterned structures

    SciTech Connect (OSTI)

    Zhang, W. Zhang, D.; Yuan, S. J.; Huang, Z. C.; Zhai, Y.; Wong, P. K. J.; Wu, J.; Xu, Y. B.

    2014-10-15

    Previous studies on epitaxial Fe{sub 3}O{sub 4} rings in the context of spin-transfer torque effect have revealed complicated and undesirable domain structures, attributed to the intrinsic fourfold magnetocrystalline anisotropy in the ferrite. In this Letter, we report a viable solution to this problem, utilizing a 6-nm-thick epitaxial Fe{sub 3}O{sub 4} thin film on GaAs(100), where the fourfold magnetocrystalline anisotropy is negligible. We demonstrate that in the Fe{sub 3}O{sub 4} planar wires patterned from our thin film, such a unique magnetic anisotropy system has been preserved, and relatively simple magnetic domain configurations compared to those previous reports can be obtained.

  17. Fluid dynamics, particulate segregation, chemical processes, and natural ore analog discussions that relate to the potential for criticality in Hanford tanks

    SciTech Connect (OSTI)

    Barney, G.S.

    1996-09-27

    This report presents an in-depth review of the potential for nuclear criticality to occur in Hanford defense waste tanks during past, current and future safe storage and maintenance operations. The report also briefly discusses the potential impacts of proposed retrieval activities, although retrieval was not a main focus of scope. After thorough review of fluid dynamic aspects that focus on particle segregation, chemical aspects that focus on solubility and adsorption processes that might concentrate plutonium and/or separate plutonium from the neutron absorbers in the tank waste, and ore-body formation and mining operations, the interdisciplinary team has come to the conclusion that there is negligible risk of nuclear critically under existing storage conditions in Hanford site underground waste storage tanks. Further, for the accident scenarios considered an accidental criticality is incredible.

  18. Measurement of cross-field power loss due to rovibrationally excited H{sub 2} in a detached hydrogen divertor plasma simulator

    SciTech Connect (OSTI)

    Hollmann, E.M.; Pigarov, A.Yu.; Yan, Z.

    2006-05-15

    The cross-field power loss due to radiation, plasma, and neutrals are measured for hydrogen discharges in a linear divertor simulator experiment. Radiation appears to be the dominant power loss channel; however, power loss due to heating of H{sub 2} neutrals is found to be quite significant, being only 2x weaker than radiation in the higher neutral pressure experiments. The H{sub 2} vibrational temperature T{sub vib} is found to be the most important channel for carrying neutral energy out of the plasma--more important than either kinetic temperature T{sub kin} or rotational temperature T{sub rot}. Power carried radially to the wall by plasma cross-field transport is found to be negligible when compared to neutral and radiation losses. These results demonstrate the importance of including of H{sub 2} neutrals in understanding power balance in detached tokamak divertors.

  19. High-resolution single-shot spectral monitoring of hard x-ray free-electron laser radiation

    SciTech Connect (OSTI)

    Makita, M.; Karvinen, P.; Zhu, D.; Juranic, P. N.; Grünert, J.; Cartier, S.; Jungmann-Smith, J. H.; Lemke, H. T.; Mozzanica, A.; Nelson, S.; Patthey, L.; Sikorski, M.; Song, S.; Feng, Y.; David, C.

    2015-10-16

    We have developed an on-line spectrometer for hard x-ray free-electron laser (XFEL) radiation based on a nanostructured diamond diffraction grating and a bent crystal analyzer. Our method provides high spectral resolution, interferes negligibly with the XFEL beam, and can withstand the intense hard x-ray pulses at high repetition rates of >100 Hz. The spectrometer is capable of providing shot-to-shot spectral information for the normalization of data obtained in scientific experiments and optimization of the accelerator operation parameters. We have demonstrated these capabilities of the setup at the Linac Coherent Light Source, in self-amplified spontaneous emission mode at full energy of >1 mJ with a 120 Hz repetition rate, obtaining a resolving power of Ε/δΕ > 3 × 104. In conclusion, the device was also used to monitor the effects of pulse duration down to 8 fs by analysis of the spectral spike width.

  20. Cryogenic Test of a Coaxial Coupling Scheme for Fundamental and Higher Order Modes in Superconducting Cavities

    SciTech Connect (OSTI)

    J.K. Sekutowicz, P. Kneisel

    2009-05-01

    A coaxial coupling device located in the beam pipe of the TESLA type superconducting cavities provides for better propagation of Higher Order Modes (HOMs) and their strong damping in appropriate HOM couplers. Additionally, it also provides efficient coupling for fundamental mode RF power into the superconducting cavity. The whole coupling device can be designed as a detachable system. If appropriately dimensioned, the magnetic field can be minimized to a negligible level at the flange position. This scheme, presented previously*, provides for several advantages: strong HOM damping, flangeable solution, exchangeability of the HOM damping device on a cavity, less complexity of the superconducting cavity, possible cost advantages. This contribution will describe the results of the first cryogenic test.

  1. Self-field effects on instability of wave modes in a two-stream free-electron laser with an axial magnetic field

    SciTech Connect (OSTI)

    Mohsenpour, Taghi Rezaee Rami, Omme Kolsoum

    2014-07-15

    Free electron lasers (FEL) play major roles in the Raman Regime, due to the charge and current densities of the beam self-field. The method of perturbation has been applied to study the influence of self-electric and self-magnetic fields. A dispersion relation for two-stream free electron lasers with a helical wiggler and an axial magnetic field has been found. This dispersion relation is solved numerically to investigate the influence of self-fields on the FEL coupling and the two-stream instability. It was found that self-fields can produce very large effects on the FEL coupling, but they have almost negligible effects on two-stream instability.

  2. Infrared Absorption Spectroscopy and Chemical Kinetics of Free Radicals, Final Technical Report

    DOE R&D Accomplishments [OSTI]

    Curl, Robert F.; Glass, Graham P.

    2004-11-01

    This research was directed at the detection, monitoring, and study of the chemical kinetic behavior by infrared absorption spectroscopy of small free radical species thought to be important intermediates in combustion. Work on the reaction of OH with acetaldehyde has been completed and published and work on the reaction of O({sup 1}D) with CH{sub 4} has been completed and submitted for publication. In the course of our investigation of branching ratios of the reactions of O({sup 1}D) with acetaldehyde and methane, we discovered that hot atom chemistry effects are not negligible at the gas pressures (13 Torr) initially used. Branching ratios of the reaction of O({sup 1}D) with CH{sub 4} have been measured at a tenfold higher He flow and fivefold higher pressure.

  3. Defect tolerant transmission lithography mask

    DOE Patents [OSTI]

    Vernon, Stephen P. (Pleasanton, CA)

    2000-01-01

    A transmission lithography mask that utilizes a transparent substrate or a partially transparent membrane as the active region of the mask. A reflective single layer or multilayer coating is deposited on the membrane surface facing the illumination system. The coating is selectively patterned (removed) to form transmissive (bright) regions. Structural imperfections and defects in the coating have negligible effect on the aerial image of the mask master pattern since the coating is used to reflect radiation out of the entrance pupil of the imaging system. Similarly, structural imperfections in the clear regions of the membrane have little influence on the amplitude or phase of the transmitted electromagnetic fields. Since the mask "discards," rather than absorbs, unwanted radiation, it has reduced optical absorption and reduced thermal loading as compared to conventional designs. For EUV applications, the mask circumvents the phase defect problem, and is independent of the thermal load during exposure.

  4. Renormalization group flow and fixed point of the lattice topological charge in the 2D O(3) {sigma} model

    SciTech Connect (OSTI)

    DElia, M.; Farchioni, F.; Papa, A.

    1997-02-01

    We study the renormalization group evolution up to the fixed point of the lattice topological susceptibility in the 2D O(3) nonlinear {sigma} model. We start with a discretization of the continuum topological charge by a local charge density polynomial in the lattice fields. Among the different choices we propose also a Symanzik-improved lattice topological charge. We check step by step in the renormalization group iteration the progressive dumping of quantum fluctuations, which are responsible for the additive and multiplicative renormalizations of the lattice topological susceptibility with respect to the continuum definition. We find that already after three iterations these renormalizations are negligible and an excellent approximation of the fixed point is achieved. We also check by an explicit calculation that the assumption of slowly varying fields in iterating the renormalization group does not lead to a good approximation of the fixed point charge operator. {copyright} {ital 1997} {ital The American Physical Society}

  5. Particle-in-cell/accelerator code for space-charge dominated beam simulation

    SciTech Connect (OSTI)

    2012-05-08

    Warp is a multidimensional discrete-particle beam simulation program designed to be applicable where the beam space-charge is non-negligible or dominant. It is being developed in a collaboration among LLNL, LBNL and the University of Maryland. It was originally designed and optimized for heave ion fusion accelerator physics studies, but has received use in a broader range of applications, including for example laser wakefield accelerators, e-cloud studies in high enery accelerators, particle traps and other areas. At present it incorporates 3-D, axisymmetric (r,z) planar (x-z) and transverse slice (x,y) descriptions, with both electrostatic and electro-magnetic fields, and a beam envelope model. The code is guilt atop the Python interpreter language.

  6. Reference electrode for strong oxidizing acid solutions

    DOE Patents [OSTI]

    Rigdon, Lester P. (Livermore, CA); Harrar, Jackson E. (Castro Valley, CA); Bullock, Sr., Jack C. (Pleasanton, CA); McGuire, Raymond R. (Brentwood, CA)

    1990-01-01

    A reference electrode for the measurement of the oxidation-reduction potentials of solutions is especially suitable for oxidizing solutions such as highly concentrated and fuming nitric acids, the solutions of nitrogen oxides, N.sub.2 O.sub.4 and N.sub.2 O.sub.5, in nitric acids. The reference electrode is fabricated of entirely inert materials, has a half cell of Pt/Ce(IV)/Ce(III)/70 wt. % HNO.sub.3, and includes a double-junction design with an intermediate solution of 70 wt. % HNO.sub.3. The liquid junctions are made from Corning No. 7930 glass for low resistance and negligible solution leakage.

  7. Method of making dense, conformal, ultra-thin cap layers for nanoporous low-k ILD by plasma assisted atomic layer deposition

    DOE Patents [OSTI]

    Jiang, Ying-Bing (Albuquerque, NM); Cecchi, Joseph L. (Albuquerque, NM); Brinker, C. Jeffrey (Albuquerque, NM)

    2011-05-24

    Barrier layers and methods for forming barrier layers on a porous layer are provided. The methods can include chemically adsorbing a plurality of first molecules on a surface of the porous layer in a chamber and forming a first layer of the first molecules on the surface of the porous layer. A plasma can then be used to react a plurality of second molecules with the first layer of first molecules to form a first layer of a barrier layer. The barrier layers can seal the pores of the porous material, function as a diffusion barrier, be conformal, and/or have a negligible impact on the overall ILD k value of the porous material.

  8. Reduction of Carbon Monoxide. Past Research Summary

    DOE R&D Accomplishments [OSTI]

    Schrock, R. R.

    1982-01-01

    Research programs for the year on the preparation, characterization, and reactions of binuclear tantalum complexes are described. All evidence to date suggest the following of these dimeric molecules: (1) the dimer does not break into monomers under mild conditions; (2) intermolecular hydride exchange is not negligible, but it is slow; (3) intermolecular non-ionic halide exchange is fast; (4) the ends of the dimers can rotate partially with respect to one another. The binuclear tantalum hydride complexes were found to react with carbon monoxide to give a molecule which is the only example of reduction of CO by a transition metal hydride to give a complex containing a CHO ligand. Isonitrides also reacted in a similar manner with dimeric tantalum hydride. (ATT)

  9. Electron acceleration by a tightly focused Hermite-Gaussian beam: higher-order corrections

    SciTech Connect (OSTI)

    Zhao Zhiguo; Yang Dangxiao; Lue Baida

    2008-03-15

    Taking the TEM{sub 1,0}-mode Hermite-Gaussian (H-G) beam as a numerical calculation example, and based on the method of the perturbation series expansion, the higher-order field corrections of H-G beams are derived and used to study the electron acceleration by a tightly focused H-G beam in vacuum. For the case of the off-axis injection the field corrections to the terms of order f{sup 3} (f=1/kw{sub 0}, k and w{sub 0} being the wavenumber and waist width, respectively) are considered, and for the case of the on-axis injection the contributions of the terms of higher orders are negligible. By a suitable optimization of injection parameters the energy gain in the giga-electron-volt regime can be achieved.

  10. Evaluation of two-stage system for neutron measurement aiming at increase in count rate at Japan Atomic Energy Agency-Fusion Neutronics Source

    SciTech Connect (OSTI)

    Shinohara, K. Ochiai, K.; Sukegawa, A.; Ishii, K.; Kitajima, S.; Baba, M.; Sasao, M.

    2014-11-15

    In order to increase the count rate capability of a neutron detection system as a whole, we propose a multi-stage neutron detection system. Experiments to test the effectiveness of this concept were carried out on Fusion Neutronics Source. Comparing four configurations of alignment, it was found that the influence of an anterior stage on a posterior stage was negligible for the pulse height distribution. The two-stage system using 25 mm thickness scintillator was about 1.65 times the count rate capability of a single detector system for d-D neutrons and was about 1.8 times the count rate capability for d-T neutrons. The results suggested that the concept of a multi-stage detection system will work in practice.

  11. Structural modifications due to interface chemistry at metal-nitride interfaces

    SciTech Connect (OSTI)

    Yadav, S. K.; Shao, S.; Wang, J.; Liu, X. -Y.

    2015-11-27

    Based on accurate first principles density functional theory (DFT) calculations, an unusual phenomenon of interfacial structural modifications, due to the interface chemistry influence is identified at two metal-nitride interfaces with strong metal-nitrogen affinity, Al/TiN {111} and Al/VN {111} interfaces. It is shown that at such interfaces, a faulted stacking structure is energetically preferred on the Al side of the interface. And both intrinsic and extrinsic stacking fault energies in the vicinity Al layers are negligibly small. However, such phenomenon does not occur in Pt/TiN and Pt/VN interfaces because of the weak Pt-N affinity. As a result, corresponding to structural energies of metal-nitride interfaces, the linear elasticity analysis predicts characteristics of interfacial misfit dislocations at metal-nitride interfaces.

  12. Nonlocal microscopic theory of quantum friction between parallel metallic slabs

    SciTech Connect (OSTI)

    Despoja, Vito

    2011-05-15

    We present a new derivation of the friction force between two metallic slabs moving with constant relative parallel velocity, based on T=0 quantum-field theory formalism. By including a fully nonlocal description of dynamically screened electron fluctuations in the slab, and avoiding the usual matching-condition procedure, we generalize previous expressions for the friction force, to which our results reduce in the local limit. Analyzing the friction force calculated in the two local models and in the nonlocal theory, we show that for physically relevant velocities local theories using the plasmon and Drude models of dielectric response are inappropriate to describe friction, which is due to excitation of low-energy electron-hole pairs, which are properly included in nonlocal theory. We also show that inclusion of dissipation in the nonlocal electronic response has negligible influence on friction.

  13. Toward crystal design in organic conductors and superconductors.

    SciTech Connect (OSTI)

    Geiser, U.

    1999-04-23

    We have seen that many different types of intermolecular interactions in organic conducting cation radical salts. Hydrogen bonding between the donor molecules and the anions is weak but not negligible. The ionic Madelung energy is insufficient to completely intersperse anions and cations, thus the layers favored by the van der Waals interactions remain intact. The search for new conducting and superconducting salts has been mainly by trial-and-error methods, even though simple substitutions have been employed in order to obtain isostructural analogs of successful (e.g., superconducting) salts. However, even seemingly minor substitutions sometimes destroy the packing type, and different crystal structures result. Simulations with the aim at predicting crystal structures have not succeeded, mainly because the different interaction types are of comparable energy, and the delocalized and partial charges render the calculations of the ionic terms extremely unreliable. Clearly, the development of suitable crystal modeling techniques with predictive capabilities is one of the great needs of the field.

  14. Impact of the control rod consumption on the reactivity control of a SFR break-even core

    SciTech Connect (OSTI)

    Blanchet, D.; Fontaine, B.

    2012-07-01

    Current design studies on Sodium Fast Reactor (SFR) differ from those performed in the past by the fact that design criteria are now those of the Generation IV reactors. In order to improve their safety, reactors with break-even cores are preferred because they minimize the needs in terms of reactivity control and limit the consequences of control rod withdrawal. Furthermore, as the reactivity control needs are low, break-even core enables the use of absorbing materials with reduced efficiency (natural boron, hafnium...). Nevertheless, the use of control rods with few absorbing materials may present the disadvantage of a non-negligible ({approx}10%) loss of efficiency due to their consumption under irradiation. This paper presents a methodology to calculate accurately and analyze this consumption. (authors)

  15. Hydrogeologic characterization of an arid zone Radioactive Waste Management Site

    SciTech Connect (OSTI)

    Ginanni, J.M.; O`Neill, L.J. [USDOE Nevada Operations Office, Las Vegas, NV (United States); Hammermeister, D.P.; Blout, D.O.; Dozier, B.L.; Sully, M.J.; Johnejack, K.R.; Emer, D.F. [Reynolds Electrical and Engineering Co., Inc., Las Vegas, NV (United States); Tyler, S.W. [Nevada Univ., Reno, NV (United States). Desert Research Inst.

    1994-06-01

    An in-depth subsurface site characterization and monitoring program for the soil water migration pathway has been planned, implemented, and completed to satisfy data requirements for a waiver from groundwater monitoring, for an exemption from liner leachate collections systems, and for different regulatory driven performance assessments. A traditional scientific approach has been taken to focus characterization and monitoring efforts. This involved developing a conceptual model of the hydrogeologic system and defining and testing hypotheses about this model. Specific hypotheses tested included: that the system was hydrologically heterogenous and anisotropic, and that recharge was very low or negligible. Mineralogical, physical, and hydrologic data collected to test hypotheses has shown the hydrologic system to be remarkably homogenous and isotropic rather than heterogenous and anisotropic. Both hydrodynamic and environmental tracer approaches for estimating recharge have led to the conclusion that recharge from the Area 5 RWMS is not occurring in the upper region of the vadose zone, and that recharge at depth is extremely small or negligible. This demonstration of ``no migration of hazardous constituents to the water table satisfies a key requirement for both the groundwater monitoring waiver and the exemption from liner leachate collection systems. Data obtained from testing hypotheses concerning the soil water migration pathway have been used to refine the conceptual model of the hydrogeologic system of the site. These data suggest that the soil gas and atmospheric air pathways may be more important for transporting contaminants to the accessible environment than the soil water pathway. New hypotheses have been developed about these pathways, and characterization and monitoring activities designed to collect data to test these hypotheses.

  16. Residual Viremia in Treated HIV+ Individuals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Conway, Jessica M.; Perelson, Alan S.

    2016-01-06

    Antiretroviral therapy (ART) effectively controls HIV infection, suppressing HIV viral loads. However, some residual virus remains, below the level of detection, in HIV-infected patients on ART. Furthermore, the source of this viremia is an area of debate: does it derive primarily from activation of infected cells in the latent reservoir, or from ongoing viral replication? Our observations seem to be contradictory: there is evidence of short term evolution, implying that there must be ongoing viral replication, and viral strains should thus evolve. The phylogenetic analyses, and rare emergent drug resistance, suggest no long-term viral evolution, implying that virus derived frommore »activated latent cells must dominate. We use simple deterministic and stochastic models to gain insight into residual viremia dynamics in HIV-infected patients. Our modeling relies on two underlying assumptions for patients on suppressive ART: that latent cell activation drives viral dynamics and that the reproductive ratio of treated infection is less than 1. Nonetheless, the contribution of viral replication to residual viremia in patients on ART may be non-negligible. However, even if the portion of viremia attributable to viral replication is significant, our model predicts (1) that latent reservoir re-seeding remains negligible, and (2) some short-term viral evolution is permitted, but long-term evolution can still be limited: stochastic analysis of our model shows that de novo emergence of drug resistance is rare. Thus, our simple models reconcile the seemingly contradictory observations on residual viremia and, with relatively few parameters, recapitulates HIV viral dynamics observed in patients on suppressive therapy.« less

  17. Preparation of water soluble L-arginine capped CdSe/ZnS QDs and their interaction with synthetic DNA: Picosecond-resolved FRET study

    SciTech Connect (OSTI)

    Giri, Anupam; Goswami, Nirmal; Lemmens, Peter; Pal, Samir Kumar

    2012-08-15

    Graphical abstract: Frster resonance energy transfer (FRET) studies on the interaction of water soluble arginine-capped CdSe/ZnS QDs with ethidium bromide (EB) labeled synthetic dodecamer DNA. Highlights: ? We have solubilized CdSe/ZnS QD in water replacing their TOPO ligand by L-arginine. ? We have studied arginine@QDDNA interaction using FRET technique. ? Arginine@QDs act as energy donor and ethidium bromide-DNA acts as energy acceptor. ? We have applied a kinetic model to understand the kinetics of energy transfer. ? Circular dichroism studies revealed negligible perturbation in the DNA B-form in the arg@QD-DNA complex. -- Abstract: We have exchanged TOPO (trioctylphosphine oxide) ligand of CdSe/ZnS core/shell quantum dots (QDs) with an amino acid L-arginine (Arg) at the toluene/water interface and eventually rendered the QDs from toluene to aqueous phase. We have studied the interaction of the water soluble Arg-capped QDs (energy donor) with ethidium (EB) labeled synthetic dodecamer DNA (energy acceptor) using picoseconds resolved Frster resonance energy transfer (FRET) technique. Furthermore, we have applied a model developed by M. Tachiya to understand the kinetics of energy transfer and the distribution of acceptor (EB-DNA) molecules around the donor QDs. Circular dichroism (CD) studies revealed a negligible perturbation in the native B-form structure of the DNA upon interaction with Arg-capped QDs. The melting and the rehybridization pathways of the DNA attached to the QDs have been monitored by the CD which reveals hydrogen bonding is the associative mechanism for interaction between Arg-capped QDs and DNA.

  18. SHORT VERSUS LONG AND COLLAPSARS VERSUS NON-COLLAPSARS: A QUANTITATIVE CLASSIFICATION OF GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Bromberg, Omer; Piran, Tsvi; Sari, Re'em [Racah Institute of Physics, The Hebrew University, 91904 Jerusalem (Israel)] [Racah Institute of Physics, The Hebrew University, 91904 Jerusalem (Israel); Nakar, Ehud [The Raymond and Berverly Sackler School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel)] [The Raymond and Berverly Sackler School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel)

    2013-02-20

    Gamma-ray bursts (GRBs) are traditionally divided into long and short according to their durations (lg2 s). It was generally believed that this reflects a different physical origin: collapsars (long) and non-collapsars (short). We have recently shown that the duration distribution of collapsars is flat, namely, independent of the duration, at short durations. Using this model for the distribution of Collapsars we determine the duration distribution of non-Collapsars and estimate the probability that a burst with a given duration (and hardness) is a Collapsar or not. We find that this probability depends strongly on the spectral window of the observing detector. While the commonly used limit of 2 s is conservative and suitable for BATSE bursts, 40% of Swift's bursts shorter than 2 s are Collapsars and the division lg0.8 s is more suitable for Swift. We find that the duration overlap of the two populations is very large. On the one hand there is a non-negligible fraction of non-Collapsars longer than 10 s, while on the other hand even bursts shorter than 0.5 s in the Swift sample have a non-negligible probability to be Collapsars. Our results enable the construction of non-Collapsar samples while controlling the Collapsar contamination. They also highlight that no firm conclusions can be drawn based on a single burst and they have numerous implications concerning previous studies of non-Collapsar properties that were based on the current significantly contaminated Swift samples of localized short GRBs. Specifically (1) all known short bursts with z > 1 are most likely Collapsars; (2) the only short burst with a clear jet break is most likely a Collapsar, indicating our lack of knowledge concerning non-Collapsar beaming; and (3) the existence of non-Collapsars with durations up to 10 s imposes new challenges to non-Collapsar models.

  19. Residual Viremia in Treated HIV+ Individuals

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Conway, Jessica M.; Perelson, Alan S.

    2016-01-06

    Antiretroviral therapy (ART) effectively controls HIV infection, suppressing HIV viral loads. However, some residual virus remains, below the level of detection, in HIV-infected patients on ART. Furthermore, the source of this viremia is an area of debate: does it derive primarily from activation of infected cells in the latent reservoir, or from ongoing viral replication? Our observations seem to be contradictory: there is evidence of short term evolution, implying that there must be ongoing viral replication, and viral strains should thus evolve. The phylogenetic analyses, and rare emergent drug resistance, suggest no long-term viral evolution, implying that virus derived frommore » activated latent cells must dominate. We use simple deterministic and stochastic models to gain insight into residual viremia dynamics in HIV-infected patients. Our modeling relies on two underlying assumptions for patients on suppressive ART: that latent cell activation drives viral dynamics and that the reproductive ratio of treated infection is less than 1. Nonetheless, the contribution of viral replication to residual viremia in patients on ART may be non-negligible. However, even if the portion of viremia attributable to viral replication is significant, our model predicts (1) that latent reservoir re-seeding remains negligible, and (2) some short-term viral evolution is permitted, but long-term evolution can still be limited: stochastic analysis of our model shows that de novo emergence of drug resistance is rare. Thus, our simple models reconcile the seemingly contradictory observations on residual viremia and, with relatively few parameters, recapitulates HIV viral dynamics observed in patients on suppressive therapy.« less

  20. Multiple scattering of electrons in solids and molecules: A cluster-model approach

    SciTech Connect (OSTI)

    Garcia de Abajo, F. J.; Van Hove, M. A.; Fadley, C. S.

    2001-02-15

    A method for the simulation of electron scattering and diffraction in solids and molecules within the cluster approach is presented with explicit applications to photoelectron diffraction, electron scattering in molecules, and low-energy electron diffraction. No approximations are made beyond the muffin-tin model, and, in particular, an exact representation of the free-electron Green function is used. All multiple-scattering paths are accounted for up to an order of scattering that ensures convergence. The method relies upon a convenient separation of the free-electron Green function in rotation matrices and translations along the z axis, which greatly reduces the computation time and storage demand. The evaluation of the multiple-scattering expansion is implemented using the fully convergent recursion method, which permits one to perform an iterative refinement of the final-state wave function, as expressed in the basis set of spherical harmonics attached to each atom of the cluster. Examples are offered in which the direct multiple-scattering expansion and the more elaborated simultaneous relaxation method fail to converge, whereas the recursion method leads to convergence. The computation time needed by the resulting computer program of electron diffraction in atomic clusters to determine the self-consistently scattered wave function is proportional to N{sup 2}(l{sub max}+1){sup 3}, where N is the number of atoms in the cluster and l{sub max} is the maximum angular momentum for which the scattering phase shifts take non-negligible values. Within this method it is possible to establish that in practical cases N>1000 might be needed for a convergence of the cluster size, although the angular averaging inherent in many experiments may reduce this. The recursion method was also modified to reduce the effort in computing angular distributions of photoelectrons and low-energy diffracted electrons, which now require negligible time for each angle of emission once the wave function has been determined for a given electron energy. Angle and energy distributions of core-level photoemission, elastic scattering of electrons from a free molecule, and low-energy electron diffraction in large-unit-cell surfaces are calculated.

  1. Diffuse γ-ray emission from galactic pulsars

    SciTech Connect (OSTI)

    Calore, F.; Di Mauro, M.; Donato, F. E-mail: mattia.dimauro@to.infn.it

    2014-11-20

    Millisecond pulsars (MSPs) are old fast-spinning neutron stars that represent the second most abundant source population discovered by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi). As guaranteed γ-ray emitters, they might contribute non-negligibly to the diffuse emission measured at high latitudes by Fermi-LAT (i.e., the Isotropic Diffuse γ-Ray Background (IDGRB)), which is believed to arise from the superposition of several components of galactic and extragalactic origin. Additionally, γ-ray sources also contribute to the anisotropy of the IDGRB measured on small scales by Fermi-LAT. In this manuscript we aim to assess the contribution of the unresolved counterpart of the detected MSPs population to the IDGRB and the maximal fraction of the measured anisotropy produced by this source class. To this end, we model the MSPs' spatial distribution in the Galaxy and the γ-ray emission parameters by considering observational constraints coming from the Australia Telescope National Facility pulsar catalog and the Second Fermi-LAT Catalog of γ-ray pulsars. By simulating a large number of MSP populations through a Monte Carlo simulation, we compute the average diffuse emission and the anisotropy 1σ upper limit. We find that the emission from unresolved MSPs at 2 GeV, where the peak of the spectrum is located, is at most 0.9% of the measured IDGRB above 10° in latitude. The 1σ upper limit on the angular power for unresolved MSP sources turns out to be about a factor of 60 smaller than Fermi-LAT measurements above 30°. Our results indicate that this galactic source class represents a negligible contributor to the high-latitude γ-ray sky and confirm that most of the intensity and geometrical properties of the measured diffuse emission are imputable to other extragalactic source classes (e.g., blazars, misaligned active galactic nuclei, or star-forming galaxies). Nevertheless, because MSPs are more concentrated toward the galactic center, we expect them to contribute significantly to the γ-ray diffuse emission at low latitudes. Because, along the galactic disk, the population of young pulsars overcomes in number that of MSPs, we compute the γ-ray emission from the whole population of unresolved pulsars, both young and millisecond, in two low-latitude regions: the inner Galaxy and the galactic center.

  2. Investigation of a Novel NDE Method for Monitoring Thermomechanical Damage and Microstructure Evolution in Ferritic-Martensitic Steels for Generation IV Nuclear Energy Systems

    SciTech Connect (OSTI)

    Nagy, Peter

    2013-09-30

    The main goal of the proposed project is the development of validated nondestructive evaluation (NDE) techniques for in situ monitoring of ferritic-martensitic steels like Grade 91 9Cr-1Mo, which are candidate materials for Generation IV nuclear energy structural components operating at temperatures up to ~650{degree}C and for steam-generator tubing for sodium-cooled fast reactors. Full assessment of thermomechanical damage requires a clear separation between thermally activated microstructural evolution and creep damage caused by simultaneous mechanical stress. Creep damage can be classified as "negligible" creep without significant plastic strain and "ordinary" creep of the primary, secondary, and tertiary kind that is accompanied by significant plastic deformation and/or cavity nucleation and growth. Under negligible creep conditions of interest in this project, minimal or no plastic strain occurs, and the accumulation of creep damage does not significantly reduce the fatigue life of a structural component so that low-temperature design rules, such as the ASME Section III, Subsection NB, can be applied with confidence. The proposed research project will utilize a multifaceted approach in which the feasibility of electrical conductivity and thermo-electric monitoring methods is researched and coupled with detailed post-thermal/creep exposure characterization of microstructural changes and damage processes using state-of-the-art electron microscopy techniques, with the aim of establishing the most effective nondestructive materials evaluation technique for particular degradation modes in high-temperature alloys that are candidates for use in the Next Generation Nuclear Plant (NGNP) as well as providing the necessary mechanism-based underpinnings for relating the two. Only techniques suitable for practical application in situ will be considered. As the project evolves and results accumulate, we will also study the use of this technique for monitoring other GEN IV materials. Through the results obtained from this integrated materials behavior and NDE study, new insight will be gained into the best nondestructive creep and microstructure monitoring methods for the particular mechanisms identified in these materials. The proposed project includes collaboration with a national laboratory partner and the results will also serve as a foundation to guide the efforts of scientists in the DOE laboratory, university, and industrial communities concerned with the technological challenges of monitoring creep and microstructural evolution in materials planned to be used in Generation IV Nuclear Energy Systems.

  3. Neutron Interactions in the CUORE Neutrinoless Double Beta Decay Experiment

    SciTech Connect (OSTI)

    Dolinski, M J

    2008-09-24

    Neutrinoless double beta decay (0{nu}DBD) is a lepton-number violating process that can occur only for a massive Majorana neutrino. The search for 0{nu}DBD is currently the only practical experimental way to determine whether neutrinos are identical to their own antiparticles (Majorana neutrinos) or have distinct particle and anti-particle states (Dirac neutrinos). In addition, the observation of 0{nu}DBD can provide information about the absolute mass scale of the neutrino. The Cuoricino experiment was a sensitive search for 0{nu}DBD, as well as a proof of principle for the next generation experiment, CUORE. CUORE will search for 0{nu}DBD of {sup 130}Te with a ton-scale array of unenriched TeO{sub 2} bolometers. By increasing mass and decreasing the background for 0{nu}DBD, the half-life sensitivity of CUORE will be a factor of twenty better than that of Cuoricino. The site for both of these experiments is the Laboratori Nazionali del Gran Sasso, an underground laboratory with 3300 meters water equivalent rock overburden and a cosmic ray muon attenuation factor of 10{sup -6}. Because of the extreme low background requirements for CUORE, it is important that all potential sources of background in the 0{nu}DBD peak region at 2530 keV are well understood. One potential source of background for CUORE comes from neutrons, which can be produced underground both by ({alpha},n) reactions and by fast cosmic ray muon interactions. Preliminary simulations by the CUORE collaboration indicate that these backgrounds will be negligible for CUORE. However, in order to accurately simulate the expected neutron background, it is important to understand the cross sections for neutron interactions with detector materials. In order to help refine these simulations, I have measured the gamma-ray production cross sections for interactions of neutrons on the abundant stable isotopes of Te using the GEANIE detector array at the Los Alamos Neutron Science Center. In addition, I have used the GEANIE data to set an upper limit for the production of a 2529 keV gamma-ray from the {sup 126}Te(n,n{prime}{gamma}) reaction. This gamma-ray is a potential source of interference for the 0{nu}DBD peak. Based on this measurement, the contribution of this line to the background is expected to be negligible.

  4. Hydrogenation of palladium rich compounds of aluminium, gallium and indium

    SciTech Connect (OSTI)

    Kohlmann, H.

    2010-02-15

    Palladium rich intermetallic compounds of aluminium, gallium and indium have been studied before and after hydrogenation by powder X-ray diffraction and during hydrogenation by in situ thermal analysis (DSC) at hydrogen gas pressures up to 39 MPa and temperatures up to 700 K. Very weak DSC signals and small unit cell increases of below 1% for AlPd{sub 2}, AlPd{sub 3}, GaPd{sub 2}, Ga{sub 5}Pd{sub 13}, In{sub 3}Pd{sub 5}, and InPd{sub 2} suggest negligible hydrogen uptake. In contrast, for both tetragonal modifications of InPd{sub 3} (ZrAl{sub 3} and TiAl{sub 3} type), heating to 523 K at 2 MPa hydrogen pressure leads to a rearrangement of the intermetallic structure to a cubic AuCu{sub 3} type with an increase in unit cell volume per formula unit by 3.6-3.9%. Gravimetric analysis suggests a composition InPd{sub 3}H{sub a}pprox{sub 0.8} for the hydrogenation product. Very similar behaviour is found for the deuteration of InPd{sub 3}. - Graphical abstract: In situ differential scanning calorimetry of the hydrogenation of tetragonal InPd{sub 3} (ZrAl{sub 3} type) at 1.3 MPa hydrogen pressure.

  5. Life cycle assessment of urban waste management: Energy performances and environmental impacts. The case of Rome, Italy

    SciTech Connect (OSTI)

    Cherubini, Francesco Bargigli, Silvia; Ulgiati, Sergio

    2008-12-15

    Landfilling is nowadays the most common practice of waste management in Italy in spite of enforced regulations aimed at increasing waste pre-sorting as well as energy and material recovery. In this work we analyse selected alternative scenarios aimed at minimizing the unused material fraction to be delivered to the landfill. The methodological framework of the analysis is the life cycle assessment, in a multi-method form developed by our research team. The approach was applied to the case of municipal solid waste (MSW) management in Rome, with a special focus on energy and material balance, including global and local scale airborne emissions. Results, provided in the form of indices and indicators of efficiency, effectiveness and environmental impacts, point out landfill activities as the worst waste management strategy at a global scale. On the other hand, the investigated waste treatments with energy and material recovery allow important benefits of greenhouse gas emission reduction (among others) but are still affected by non-negligible local emissions. Furthermore, waste treatments leading to energy recovery provide an energy output that, in the best case, is able to meet 15% of the Rome electricity consumption.

  6. Asymmetric radiative damping of low shear toroidal Alfven eigenmodes

    SciTech Connect (OSTI)

    Nyqvist, R. M.; Sharapov, S. E.

    2012-08-15

    Radiative damping of toroidicity-induced Alfven eigenmodes (TAEs) in tokamaks, caused by coupling to the kinetic Alfven wave (KAW), is investigated analytically in the limit of low magnetic shear. A significant asymmetry is found between the radiative damping of the odd TAE, whose frequency lies above the central TAE gap frequency {omega}{sub 0}, and that of the even TAE, with frequency {omega}<{omega}{sub 0}. For the even TAE, which consists of a symmetric combination of neighboring poloidal harmonics (and therefore has ballooning-type mode structure), the coupling results in two non-overlapping, outgoing fluxes of KAWs that propagate radially away from each other and the TAE localization region. In contrast, the odd TAE consists of an antisymmetric combination of neighboring poloidal harmonics, resulting in anti-ballooning mode structure. For this mode, the KAWs initially propagate towards each other and form an interference pattern in the TAE localization region, resulting in a negligibly small escaping flux and a correspondingly low radiative damping rate. As a result of the up/down asymmetry in radiative damping with respect to the mode frequency, the odd TAE may be destabilized by fusion born alpha particles more easily than the usual, even TAE.

  7. Weldon Spring historical dose estimate

    SciTech Connect (OSTI)

    Meshkov, N.; Benioff, P.; Wang, J.; Yuan, Y.

    1986-07-01

    This study was conducted to determine the estimated radiation doses that individuals in five nearby population groups and the general population in the surrounding area may have received as a consequence of activities at a uranium processing plant in Weldon Spring, Missouri. The study is retrospective and encompasses plant operations (1957-1966), cleanup (1967-1969), and maintenance (1969-1982). The dose estimates for members of the nearby population groups are as follows. Of the three periods considered, the largest doses to the general population in the surrounding area would have occurred during the plant operations period (1957-1966). Dose estimates for the cleanup (1967-1969) and maintenance (1969-1982) periods are negligible in comparison. Based on the monitoring data, if there was a person residing continually in a dwelling 1.2 km (0.75 mi) north of the plant, this person is estimated to have received an average of about 96 mrem/yr (ranging from 50 to 160 mrem/yr) above background during plant operations, whereas the dose to a nearby resident during later years is estimated to have been about 0.4 mrem/yr during cleanup and about 0.2 mrem/yr during the maintenance period. These values may be compared with the background dose in Missouri of 120 mrem/yr.

  8. Effects of electron recirculation on a hard x-ray source observed during the interaction of a high intensity laser pulse with thin Au targets

    SciTech Connect (OSTI)

    Compant La Fontaine, A.; Courtois, C.; Lefebvre, E.; Bourgade, J. L.; Landoas, O.; Thorp, K.; Stoeckl, C.

    2013-12-15

    The interaction of a high intensity laser pulse on the preplasma of a high-Z solid target produced by the pulse's pedestal generates high-energy electrons. These electrons subsequently penetrate inside the solid target and produce bremsstrahlung photons, generating an x-ray source which can be used for photonuclear studies or to radiograph high area density objects. The source characteristics are compared for targets with thin (20 μm) and thick (100 μm) Au foils on the Omega EP laser at Laboratory for Laser Energetics. Simulations using the particle-in-cell code CALDER show that for a 20 μm thickness Au target, electrons perform multiple round-trips in the target under the effect of the laser ponderomotive potential and the target electrostatic potential. These relativistic electrons have random transverse displacements, with respect to the target normal, attributed to electrostatic fluctuation fields. As a result, the x-ray spot size is increased by a factor 2 for thin target compared to thick targets, in agreement with experimental results. In addition, the computed doses agree with the measured ones provided that electron recirculation in the thin target is taken into account. A dose increase by a factor 1.7 is then computed by allowing for recirculation. In the 100 μm target case, on the other hand, this effect is found to be negligible.

  9. Inward Lithium-Ion Breathing of Hierarchically Porous Silicon Anodes

    SciTech Connect (OSTI)

    Xiao, Qiangfeng; Gu, Meng; Yang, Hui; Li, Bing; Zhang, Cunman; Liu, Yang; Liu, Fang; Dai, Fang; Yang, Li; Liu, Zhongyi; Xiao, Xingcheng; Liu, Gao; Zhao, Peng; Zhang, Sulin; Wang, Chong M.; Lu, Yunfeng; Cai, Mei

    2015-11-05

    Silicon has been identified as one of the most promising candidates as anode for high performance lithium-ion batteries. The key challenge for Si anodes is the large volume change induced chemomechanical fracture and subsequent rapid capacity fading upon cyclic charge and discharge. Improving capacity retention thus critically relies on smart accommodation of the volume changes through nanoscale structural design. In this work, we report a novel fabrication method for hierarchically porous Si nanospheres (hp-SiNSs), which consist of a porous shell and a hollow core. Upon charge/discharge cycling, the hp-SiNSs accommodate the volume change through reversible inward expansion/contraction with negligible particle-level outward expansion. Our mechanics analysis revealed that such a unique volume-change accommodation mechanism is enabled by the much stiffer modulus of the lithiated layer than the unlithiated porous layer and the low flow stress of the porous structure. Such inward expansion shields the hp-SiNSs from fracture, opposite to the outward expansion in solid Si during lithiation. Lithium ion battery assembled with this new nanoporous material exhibits high capacity, high power, long cycle life and high coulombic efficiency, which is superior to the current commercial Si-based anode materials. The low cost synthesis approach reported here provides a new avenue for the rational design of hierarchically porous structures with unique materials properties.

  10. Response to"Analysis of the Treatment, by the U.S. Department of Energy, of the FEP Hydrothermal Activity in the Yucca Mountain Performance Assessment" by Yuri Dublyansky

    SciTech Connect (OSTI)

    Houseworth, J.E.; Hardin, E.

    2008-11-17

    This paper presents a rebuttal to Dublyansky (2007), which misrepresents technical issues associated with hydrothermal activity at the proposed Yucca Mountain nuclear waste repository and their importance to the long-term performance of the repository. In this paper, questions associated with hydrothermal activity are reviewed and the justification for exclusion of hydrothermal activity from performance assessment is presented. The hypothesis that hydrothermal upwelling into the present-day unsaturated zone has occurred at Yucca Mountain is refuted by the unambiguous evidence that secondary minerals and fluid inclusions in the unsaturated zone formed in an unsaturated environment from downward percolating meteoric waters. The thermal history at Yucca Mountain, inferred from fluid inclusion and isotopic data, is explained in terms of the tectonic extensional environment and associated silicic magmatism. The waning of tectonic extension over millions of years has led to the present-day heat flux in the Yucca Mountain region that is below average for the Great Basin. The long time scales of tectonic processes are such that any effects of a resumption of extension or silicic magmatism on hydrothermal activity at Yucca Mountain over the 10,000-year regulatory period would be negligible. The conclusion that hydrothermal activity was incorrectly excluded from performance assessment as asserted in Dublyansky (2007) is contradicted by the available technical and regulatory information.

  11. PROBLEM DEPENDENT DOPPLER BROADENING OF CONTINUOUS ENERGY CROSS SECTIONS IN THE KENO MONTE CARLO COMPUTER CODE

    SciTech Connect (OSTI)

    Hart, S. W. D.; Maldonado, G. Ivan; Celik, Cihangir; Leal, Luiz C

    2014-01-01

    For many Monte Carlo codes cross sections are generally only created at a set of predetermined temperatures. This causes an increase in error as one moves further and further away from these temperatures in the Monte Carlo model. This paper discusses recent progress in the Scale Monte Carlo module KENO to create problem dependent, Doppler broadened, cross sections. Currently only broadening the 1D cross sections and probability tables is addressed. The approach uses a finite difference method to calculate the temperature dependent cross-sections for the 1D data, and a simple linear-logarithmic interpolation in the square root of temperature for the probability tables. Work is also ongoing to address broadening theS (alpha , beta) tables. With the current approach the temperature dependent cross sections are Doppler broadened before transport starts, and, for all but a few isotopes, the impact on cross section loading is negligible. Results can be compared with those obtained by using multigroup libraries, as KENO currently does interpolation on the multigroup cross sections to determine temperature dependent cross-sections. Current results compare favorably with these expected results.

  12. Analysis on storage off-gas emissions from woody, herbaceous, and torrefied biomass

    SciTech Connect (OSTI)

    Tumuluru, Jaya Shankar; Lim, C. Jim; Bi, Xiaotao T.; Kuang, Xingya; Melin, Staffan; Yazdanpanah, Fahimeh; Sokhansanj, Shahab

    2015-03-02

    Wood chips, torrefied wood chips, ground switchgrass, and wood pellets were tested for off-gas emissions during storage. Storage canisters with gas-collection ports were used to conduct experiments at room temperature of 20 C and in a laboratory oven set at 40 C. Commercially-produced wood pellets yielded the highest carbon monoxide (CO) emissions at both 20 and 40 C (1600 and 13,000 ppmv), whereas torrefied wood chips emitted the lowest of about <200 and <2000 ppmv. Carbon dioxide (CO?) emissions from wood pellets were 3000 ppmv and 42,000 ppmv, whereas torrefied wood chips registered at about 2000 and 25,000 ppmv, at 20 and 40 C at the end of 11 days of storage. CO emission factors (milligrams per kilogram of biomass) calculated were lowest for ground switchgrass and torrefied wood chips (2.68 and 4.86 mg/kg) whereas wood pellets had the highest CO of about 10.60 mg/kg, respectively, at 40 C after 11 days of storage. In the case of CO?, wood pellets recorded the lowest value of 55.46 mg/kg, whereas switchgrass recorded the highest value of 318.72 mg/kg. This study concludes that CO emission factor is highest for wood pellets, CO? is highest for switchgrass and CH? is negligible for all feedstocks except for wood pellets, which is about 0.374 mg/kg at the end of 11-day storage at 40 C.

  13. Hygrothermal Simulation of Foundations: Part 1 - Soil Material Properties

    SciTech Connect (OSTI)

    Kehrer, Manfred; Pallin, Simon B

    2012-10-01

    The hygrothermal performance of soils coupled to buildings is a complicated process. A computational approach for heat transfer through the ground has been well defined (EN ISO 13370:2007, 2007), and simplified methods have been developed (Staszczuk, Radon, and Holm 2010). However, these approaches generally ignore the transfer of soil moisture, which is not negligible (Janssen, Carmeliet, and Hens 2004). This study is divided into several parts. The intention of the first part is to gather, comprehend and adapt soil properties from Soil Science. The obtained information must be applicable to related tasks in Building Science and validated with hygrothermal calculation tools. Future parts of this study will focus on the validation aspect of the soil properties to be implemented. Basic changes in the software code may be requested at this time. Different types of basement construction will be created with a hygrothermal calculation tool, WUFI. Simulations from WUFI will be compared with existing or ongoing measurements. The intentions of the first part of this study have been fulfilled. The soil properties of interest in Building Science have been defined for 12 different soil textures. These properties will serve as input parameters when performing hygrothermal calculations of building constructions coupled to soil materials. The reliability of the soil parameters will be further evaluated with measurements in Part 2.

  14. Assessment of the Electrohol process to manufacture acetaldehyde from ethanol electrogeneratively. Final report

    SciTech Connect (OSTI)

    Trevino, A.A.

    1985-04-10

    Preliminary process economics data for the electrogenerative process to manufacture acetaldehyde from ethanol were generated based on patent information. The technology was assessed in four alternative processing options. The Electrohol process is viable in the US only if integrated to the production of 190 pf ethanol from corn in a large scale unit. To be competitive, the Electrohol process must show yields in excess of 93%. Its attractiveness depends on corn prices remaining under $2.90/bu and DDG selling for more than $132/T. A corn price of $2.00/bu is needed to make a farm-size corn-based processing alternative competitive. A plant based on the fermentation of molasses proved too expensive under the US economic assumptions. The Electrohol technology based on purchased ethanol cannot compete with the existing ethylene-based process under current conditions. To become attractive, the Electrohol process must have access to cheap ethanol ($1.43/gal). The zero electricity generation mode is the most attractive mode of operation for the Electrohol technology in the US. The penalty for low levels of generation (0.130 kwh/kg AcH) is, however, negligible. The optimum operating mode in W. Europe is the generation of 0.312 kwh/kg AcH. In Japan, the low generation level is perferred (0.130 kwh/kg AcH). In general, higher energy prices improve the competitiveness of the Electrohol processing alternatives.

  15. Experience in operating the Bratsk Reservoir

    SciTech Connect (OSTI)

    Nazarov, A.V.

    1984-04-01

    The Bratsk reservoir is the largest in the USSR and second largest in the world. Initially, the reservoir was expected to be filled by the end of 1966. However, the actual filling was not completed until September of 1967. During filling and in the first years of operation it was constantly necessary to deal with floating timber in order to ensure normal operation of the hydrostation, navigation safety, conditions for fishery, and fulfillment of the sanitary requirements. During seasonal variations of the reservoir level about 160 sq km of the shore zone was subjected to variable flooding and waterlogging. Maximum erosion occurred on expanded stretches, and within their limits on slopes composed of loam and sand deposits. Within the narrows, where the banks are composed mainly of hard and soft rocks and wave action is weak, erosion is negligible. Wind setup and setdown cause maximum denivellation of the water surface. The maximum increase of the level during setup reaches 232 cm and the maximum decrease during setdown is 24 cm. Seiche oscillations with various amplitudes and periods are observed on the reservoir surface. The main uses of the complex are hydropower, water transport, timber floating, water supply, and fishery. For the successful development of the shores of reservoirs it is necessary to select the construction sites with consideration of possible occurrence of karstic and landslide processes; the construction of heavy structures requires special karst-control measures. 3 references, 3 figures, 1 table.

  16. Magnetic field transfer device and method

    DOE Patents [OSTI]

    Wipf, S.L.

    1990-02-13

    A magnetic field transfer device includes a pair of oppositely wound inner coils which each include at least one winding around an inner coil axis, and an outer coil which includes at least one winding around an outer coil axis. The windings may be formed of superconductors. The axes of the two inner coils are parallel and laterally spaced from each other so that the inner coils are positioned in side-by-side relation. The outer coil is outwardly positioned from the inner coils and rotatable relative to the inner coils about a rotational axis substantially perpendicular to the inner coil axes to generate a hypothetical surface which substantially encloses the inner coils. The outer coil rotates relative to the inner coils between a first position in which the outer coil axis is substantially parallel to the inner coil axes and the outer coil augments the magnetic field formed in one of the inner coils, and a second position 180[degree] from the first position, in which the augmented magnetic field is transferred into the other inner coil and reoriented 180[degree] from the original magnetic field. The magnetic field transfer device allows a magnetic field to be transferred between volumes with negligible work being required to rotate the outer coil with respect to the inner coils. 16 figs.

  17. Magnetic field transfer device and method

    DOE Patents [OSTI]

    Wipf, Stefan L. (Hamburg, DE)

    1990-01-01

    A magnetic field transfer device includes a pair of oppositely wound inner coils which each include at least one winding around an inner coil axis, and an outer coil which includes at least one winding around an outer coil axis. The windings may be formed of superconductors. The axes of the two inner coils are parallel and laterally spaced from each other so that the inner coils are positioned in side-by-side relation. The outer coil is outwardly positioned from the inner coils and rotatable relative to the inner coils about a rotational axis substantially perpendicular to the inner coil axes to generate a hypothetical surface which substantially encloses the inner coils. The outer coil rotates relative to the inner coils between a first position in which the outer coil axis is substantially parallel to the inner coil axes and the outer coil augments the magnetic field formed in one of the inner coils, and a second position 180.degree. from the first position, in which the augmented magnetic field is transferred into the other inner coil and reoriented 180.degree. from the original magnetic field. The magnetic field transfer device allows a magnetic field to be transferred between volumes with negligible work being required to rotate the outer coil with respect to the inner coils.

  18. Enhanced memory effect via quantum confinement in 16?nm InN nanoparticles embedded in ZnO charge trapping layer

    SciTech Connect (OSTI)

    El-Atab, Nazek; Nayfeh, Ammar; Cimen, Furkan; Alkis, Sabri; Orta, Blend; Alevli, Mustafa; Dietz, Nikolaus; Okyay, Ali K.

    2014-06-23

    In this work, the fabrication of charge trapping memory cells with laser-synthesized indium-nitride nanoparticles (InN-NPs) embedded in ZnO charge trapping layer is demonstrated. Atomic layer deposited Al{sub 2}O{sub 3} layers are used as tunnel and blocking oxides. The gate contacts are sputtered using a shadow mask which eliminates the need for any lithography steps. High frequency C-V{sub gate} measurements show that a memory effect is observed, due to the charging of the InN-NPs. With a low operating voltage of 4?V, the memory shows a noticeable threshold voltage (V{sub t}) shift of 2?V, which indicates that InN-NPs act as charge trapping centers. Without InN-NPs, the observed memory hysteresis is negligible. At higher programming voltages of 10?V, a memory window of 5?V is achieved and the V{sub t} shift direction indicates that electrons tunnel from channel to charge storage layer.

  19. Low power zinc-oxide based charge trapping memory with embedded silicon nanoparticles via poole-frenkel hole emission

    SciTech Connect (OSTI)

    El-Atab, Nazek; Nayfeh, Ammar; Ozcan, Ayse; Alkis, Sabri; Okyay, Ali K.; Department of Electrical and Electronics Engineering, Bilkent University, 06800 Ankara

    2014-01-06

    A low power zinc-oxide (ZnO) charge trapping memory with embedded silicon (Si) nanoparticles is demonstrated. The charge trapping layer is formed by spin coating 2?nm silicon nanoparticles between Atomic Layer Deposited ZnO steps. The threshold voltage shift (?V{sub t}) vs. programming voltage is studied with and without the silicon nanoparticles. Applying ?1?V for 5?s at the gate of the memory with nanoparticles results in a ?V{sub t} of 3.4?V, and the memory window can be up to 8?V with an excellent retention characteristic (>10 yr). Without nanoparticles, at ?1?V programming voltage, the ?V{sub t} is negligible. In order to get ?V{sub t} of 3.4?V without nanoparticles, programming voltage in excess of 10?V is required. The negative voltage on the gate programs the memory indicating that holes are being trapped in the charge trapping layer. In addition, at 1?V the electric field across the 3.6?nm tunnel oxide is calculated to be 0.36 MV/cm, which is too small for significant tunneling. Moreover, the ?V{sub t} vs. electric field across the tunnel oxide shows square root dependence at low fields (E??2.7 MV/cm). This indicates that Poole-Frenkel Effect is the main mechanism for holes emission at low fields and Phonon Assisted Tunneling at higher fields.

  20. Ionic Liquids with Ammonium Cations as Lubricants or Additives

    SciTech Connect (OSTI)

    Qu, Jun; Blau, Peter Julian; Dai, Sheng; Luo, Huimin; Truhan, Jr., John J

    2006-01-01

    Friction and wear are estimated to cost 6% of the US gross national product, or around $700 billion annually. A new class of more effective lubricants could lead to huge energy savings. Limited recent literature has suggested potential for using room-temperature ionic liquids as lubricants, however only a few out of millions (or more) of species have been evaluated. Recent ORNL work discovered a new category of ionic liquids with ammonium cations that have demonstrated promising lubricating properties as net lubricants or lubricant additives, particularly in lubricating difficult-to-lubricate metals like aluminum. More than 30% friction reduction has been observed on ammonium-based ionic liquids compared to conventional hydrocarbon oils. The inherent polarity of ionic liquids is believed to provide strong adhesion to contact surfaces and form a boundary lubricating film leading to friction and wear reductions. Other advantages of ionic liquids include (1) negligible volatility, (2) high thermal stability, (3) non-flammability, and (4) better intrinsic properties that eliminate the necessity of many expensive lubricant additives. With very flexible molecular structures, this new class of lubricants, particularly ammonium-based ionic liquids, can be tailored to fit a big variety of applications including but not limited to bearings, combustion engines, MEMS, and metal forming.

  1. Deployment of an alternative cover and final closure of the Mixed Waste Landfill, Sandia National Laboratories, Albuquerque, New Mexico.

    SciTech Connect (OSTI)

    Peace, Gerald L.; Goering, Timothy James; McVey, Michael David (GRAM, Inc., Albuquerque, NM); Borns, David James

    2003-06-01

    An alternative cover design consisting of a monolithic layer of native soil is proposed as the closure path for the Mixed Waste Landfill at Sandia National Laboratories, New Mexico. The proposed design would rely upon soil thickness and evapotranspiration to provide long-term performance and stability, and would be inexpensive to build and maintain. The proposed design is a 3-ft-thick, vegetated soil cover. The alternative cover meets the intent of RCRA Subtitle C regulations in that: (a) water migration through the cover is minimized; (b) maintenance is minimized by using a monolithic soil layer; (c) cover erosion is minimized by using erosion control measures; (d) subsidence is accommodated by using a ''soft'' design; and (e) the permeability of the cover is less than or equal to that of natural subsurface soil present. Performance of the proposed cover is integrated with natural site conditions, producing a ''system performance'' that will ensure that the cover is protective of human health and the environment. Natural site conditions that will produce a system performance include: (a) extremely low precipitation and high potential evapotranspiration; (b) negligible recharge to groundwater; (c) an extensive vadose zone; (d) groundwater approximately 500 ft below the surface; and (e) a versatile, native flora that will persist indefinitely as a climax ecological community with little or no maintenance.

  2. Searching for Stopped Gluinos at CMS

    SciTech Connect (OSTI)

    Ratnikov, Fedor

    2010-02-10

    We describe plans for a search for long-lived particles which will become stopped by the CMS detector. We will look for the subsequent decay of these particles during time intervals where there are no pp collisions in CMS: during gaps between crossings in the LHC beam structure, and during inter-fill periods between the beam being dumped and re-injection. Such long living particles decays will be recorded with dedicated calorimeter triggers. For models predicting these particles, such as split-susy gluinos, the large cross-section combined with good stopping power of CMS, yields a significant number of triggerable decays. If LHC instantaneous luminosity approaches 10{sup 32} cm{sup -2}s{sup -1} in 2009-10, 5sigma significance can be established in a matter of days, since these decays occur on top of a negligible background.Due to limited size, this paper concentrates on main idea and expected results. More details are available in https://twiki.cern.ch/twiki/bin/view/CMS/PhysicsResults.

  3. Electrodeposition of nickel from low temperature sulfamate electrolytes.Part 1 :Electrochemistry and film stress.

    SciTech Connect (OSTI)

    Hachman, John T.; Kelly, J.J. (IBM Talin, Albert Alec; Goods, Steven Howard

    2005-11-01

    The film stress of Ni films deposited at near-ambient temperatures from sulfamate electrolytes was studied. The particulate filtering of the electrolyte, a routine industrial practice, becomes an important deposition parameter at lower bath temperatures. At 28 C, elevated tensile film stress develops at low current densities (<10 mA/cm{sup 2}) if the electrolyte is filtered. Filtering at higher current densities has a negligible effect on film stress. A similar though less pronounced trend is observed at 32 C. Sulfate-based Ni plating baths display similar film stress sensitivity to filtering, suggesting that this is a general effect for Ni electrodeposition. It is shown that filtering does not significantly change the current efficiency or the pH near the surface during deposition. The observed changes in film stress are thus attributed not to adsorbed hydrogen but instead to the effects of filtering on the formation and concentration of polyborate species due to the decreased solubility of boric acid at near-ambient temperatures.

  4. Electronic structure of the heavy-fermion caged compound Ce?Pd??X? (X = Si, Ge) studied by density functional theory and photoelectron spectroscopy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yamaoka, Hitoshi; Jarrige, Ignace; Schwier, Eike F.; Arita, Masashi; Shimada, Kenya; Tsujii, Naohito; Jiang, Jian; Hayashi, Hirokazu; Iwasawa, Hideaki; Namatame, Hirofumi; et al

    2015-03-30

    The electronic structure of Ce?Pd??X? (X = Si, Ge) has been studied using detailed density functional theory (DFT) calculations and high-resolution photoelectron spectroscopy (PES) measurements. The orbital decomposition of the electronic structure by DFT calculations indicates that Ce atoms at the (8c) site surrounded by 16 Pd atoms have a more localized nature and a tendency to be magnetic. Ce atoms in the (4a) site surrounded by 12 Pd and 6 X atoms, on the other, show only a negligible magnetic moment. In the photoemission valence-band spectra we observe a strong f? (Ce??) component with a small fraction of fmore(Ce?) component. The spectral weight of f component near the Fermi level Ce?Pd??Si? is stronger than that for Ce?Pd??Ge? at the 4d-4f resonance, suggesting stronger c-f hybridization in the former. This may hint to the origin of the large electronic specific coefficient of Ce?Pd??Si? compared to Ce?Pd??Ge?.less

  5. Disformal theories of gravity: from the solar system to cosmology

    SciTech Connect (OSTI)

    Sakstein, Jeremy

    2014-12-01

    This paper is concerned with theories of gravity that contain a scalar coupled both conformally and disformally to matter through the metric. By systematically deriving the non-relativistic limit, it is shown that no new non-linear screening mechanisms are present beyond the Vainshtein mechanism and chameleon-like screening. If one includes the cosmological expansion of the universe, disformal effects that are usually taken to be absent can be present in the solar system. When the conformal factor is absent, fifth-forces can be screened on all scales when the cosmological field is slowly-rolling. We investigate the cosmology of these models and use local tests of gravity to place new constraints on the disformal coupling and find M?>O(eV), which is not competitive with laboratory tests. Finally, we discuss the future prospects for testing these theories and the implications for other theories of modified gravity. In particular, the Vainshtein radius of solar system objects can be altered from the static prediction when cosmological time-derivatives are non-negligible.

  6. Development of high performance scientific components for interoperability of computing packages

    SciTech Connect (OSTI)

    Gulabani, Teena Pratap

    2008-12-01

    Three major high performance quantum chemistry computational packages, NWChem, GAMESS and MPQC have been developed by different research efforts following different design patterns. The goal is to achieve interoperability among these packages by overcoming the challenges caused by the different communication patterns and software design of each of these packages. A chemistry algorithm is hard to develop as well as being a time consuming process; integration of large quantum chemistry packages will allow resource sharing and thus avoid reinvention of the wheel. Creating connections between these incompatible packages is the major motivation of the proposed work. This interoperability is achieved by bringing the benefits of Component Based Software Engineering through a plug-and-play component framework called Common Component Architecture (CCA). In this thesis, I present a strategy and process used for interfacing two widely used and important computational chemistry methodologies: Quantum Mechanics and Molecular Mechanics. To show the feasibility of the proposed approach the Tuning and Analysis Utility (TAU) has been coupled with NWChem code and its CCA components. Results show that the overhead is negligible when compared to the ease and potential of organizing and coping with large-scale software applications.

  7. Effect of ZnO seed layer on the morphology and optical properties of ZnO nanorods grown on GaN buffer layers

    SciTech Connect (OSTI)

    Nandi, R. Mohan, S. Major, S. S.; Srinivasa, R. S.

    2014-04-24

    ZnO nanorods were grown by chemical bath deposition on sputtered, polycrystalline GaN buffer layers with and without ZnO seed layer. Scanning electron microscopy and X-ray diffraction show that the ZnO nanorods on GaN buffer layers are not vertically well aligned. Photoluminescence spectrum of ZnO nanorods grown on GaN buffer layer, however exhibits a much stronger near-band-edge emission and negligible defect emission, compared to the nanorods grown on ZnO buffer layer. These features are attributed to gallium incorporation at the ZnO-GaN interface. The introduction of a thin (25 nm) ZnO seed layer on GaN buffer layer significantly improves the morphology and vertical alignment of ZnO-NRs without sacrificing the high optical quality of ZnO nanorods on GaN buffer layer. The presence of a thick (200 nm) ZnO seed layer completely masks the effect of the underlying GaN buffer layer on the morphology and optical properties of nanorods.

  8. Occurrence of Knudsen minima in diverging microchannels

    SciTech Connect (OSTI)

    Hemadri, Vadiraj; Bhandarkar, Upendra; Agrawal, Amit

    2014-12-09

    Rarefied gas flow is gaining increasing importance with the emergence of Micro Electro Mechanical Systems (MEMS). Knudsen minima is one of the characteristic feature of such rarefied flows and has been observed in uniform cross section channels such as plane channel, cylindrical tube and annulus. However, data pertaining to gaseous flow in varying cross section channel is relatively sparse. Channels of varying cross section are frequently encountered in MEMS devices and are fundamental to the design of micro-scale nozzles and micro-valves. In this context, rarefied gas flow through a diverging microchannel (divergence angle 12 degree) is studied experimentally with three different gases (argon, nitrogen and oxygen). The experiments are performed over a wide range with the mean Knudsen number varying from slip to the transitional regime (0.07 to 1.2). It is found that the effect of molecular weight of the gas on the non-dimensional mass flow rate is negligible. The Knudsen minima is experimentally observed for the first time in microchannel of non-uniform cross section.

  9. Modulation of contact resistance between metal and graphene by controlling the graphene edge, contact area, and point defects: An ab initio study

    SciTech Connect (OSTI)

    Ma, Bo; Wen, Yanwei E-mail: bshan@mail.hust.edu.cn; Gong, Cheng; Cho, Kyeongjae; Chen, Rong; Shan, Bin E-mail: bshan@mail.hust.edu.cn

    2014-05-14

    A systematic first-principles non-equilibrium Green's function study is conducted on the contact resistance between a series of metals (Au, Ag, Pt, Cu, Ni, and Pd) and graphene in the side contact geometry. Different factors such as the termination of the graphene edge, contact area, and point defect in contacted graphene are investigated. Notable differences are observed in structural configurations and electronic transport characteristics of these metal-graphene contacts, depending on the metal species and aforementioned influencing factors. It is found that the enhanced chemical reactivity of the graphene due to dangling bonds from either the unsaturated graphene edge or point defects strengthens the metal-graphene bonding, leading to a considerable contact resistance reduction for weakly interacting metals Au and Ag. For stronger interacting metals Pt and Cu, a slightly reduced contact resistance is found due to such influencing factors. However, the wetting metals Ni and Pd most strongly hybridize with graphene, exhibiting negligible dependence on the above influencing factors. This study provides guidance for the optimization of metal-graphene contacts at an atomic scale.

  10. Environmental factors affecting long-term stabilization of radon suppression covers for uranium mill tailings

    SciTech Connect (OSTI)

    Young, J.K.; Long, L.W.; Reis, J.W.

    1982-04-01

    Pacific Northwest Laboratory is investigating the use of a rock armoring blanket (riprap) to mitigate wind and water erosion of an earthen radon suppression cover applied to uranium mill tailings. To help determine design stresses for the tailings piles, environmental parameters are characterized for the five active uranium-producing regions on a site-specific basis. Only conventional uranium mills that are currently operating or that are scheduled to open in the mid 1980s are considered. Available data indicate that flooding has the most potential for disrupting a tailings pile. The arid regions of the Wyoming Basins and the Colorado Plateau are subject to brief storms of high intensity. The Texas Gulf Coast has the highest potential for extreme precipitation from hurricane-related storms. Wind data indicate average wind speeds from 3 to 6 m/sec for the sites, but extremes of 40 m/sec can be expected. Tornado risks range from low to moderate. The Colorado Plateau has the highest seismic potential, with maximum acceleration caused by earthquakes ranging from 0.2 to 0.4 g. Any direct effect from volcanic eruption is negligible, as all mills are located 90 km or more from an igneous or hydrothermal system.

  11. Encoding technique for high data compaction in data bases of fusion devices

    SciTech Connect (OSTI)

    Vega, J.; Cremy, C.; Sanchez, E.; Portas, A.

    1996-12-01

    At present, data requirements of hundreds of Mbytes/discharge are typical in devices such as JET, TFTR, DIII-D, etc., and these requirements continue to increase. With these rates, the amount of storage required to maintain discharge information is enormous. Compaction techniques are now essential to reduce storage. However, general compression techniques may distort signals, but this is undesirable for fusion diagnostics. We have developed a general technique for data compression which is described here. The technique, which is based on delta compression, does not require an examination of the data as in delayed methods. Delta values are compacted according to general encoding forms which satisfy a prefix code property and which are defined prior to data capture. Several prefix codes, which are bit oriented and which have variable code lengths, have been developed. These encoding methods are independent of the signal analog characteristics and enable one to store undistorted signals. The technique has been applied to databases of the TJ-I tokamak and the TJ-IU torsatron. Compaction rates of over 80{percent} with negligible computational effort were achieved. Computer programs were written in ANSI C, thus ensuring portability and easy maintenance. We also present an interpretation, based on information theory, of the high compression rates achieved without signal distortion. {copyright} {ital 1996 American Institute of Physics.}

  12. WIYN open cluster study. LXII. Comparison of isochrone systems using deep multi-band photometry of M35

    SciTech Connect (OSTI)

    Thompson, B.; Frinchaboy, P.; Kinemuchi, K.; Sarajedini, A.; Cohen, R.

    2014-11-01

    The current generation of stellar isochrone models exhibits non-negligible discrepancies due to variations in the input physics. The success of each model is determined by how well it fits the observations, and this paper aims to disentangle contributions from the various physical inputs. New deep, wide-field optical and near-infrared photometry (UBVRIJHK{sub S} ) of the cluster M35 is presented, against which several isochrone systems are compared: Padova, PARSEC, Dartmouth, and Y {sup 2}. Two different atmosphere models are applied to each isochrone: ATLAS9 and BT-Settl. For any isochrone set and atmosphere model, observed data are accurately reproduced for all stars more massive than 0.7 M {sub ?}. For stars less massive than 0.7 M {sub ?}, Padova and PARSEC isochrones consistently produce higher temperatures than observed. Dartmouth and Y{sup 2} isochrones with BT-Settl atmospheres reproduce optical data accurately; however, they appear too blue in IR colors. It is speculated that molecular contributions to stellar spectra in the near-infrared may not be fully explored, and that future study may reconcile these differences.

  13. Relationship between Particle Size Distribution of Low-Rank Pulverized Coal and Power Plant Performance

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ganguli, Rajive; Bandopadhyay, Sukumar

    2012-01-01

    Tmore » he impact of particle size distribution (PSD) of pulverized, low rank high volatile content Alaska coal on combustion related power plant performance was studied in a series of field scale tests. Performance was gauged through efficiency (ratio of megawatt generated to energy consumed as coal), emissions (SO 2 , NO x , CO), and carbon content of ash (fly ash and bottom ash). The study revealed that the tested coal could be burned at a grind as coarse as 50% passing 76 microns, with no deleterious impact on power generation and emissions. The PSD’s tested in this study were in the range of 41 to 81 percent passing 76 microns. There was negligible correlation between PSD and the followings factors: efficiency, SO 2 , NO x , and CO. Additionally, two tests where stack mercury (Hg) data was collected, did not demonstrate any real difference in Hg emissions with PSD. The results from the field tests positively impacts pulverized coal power plants that burn low rank high volatile content coals (such as Powder River Basin coal). These plants can potentially reduce in-plant load by grinding the coal less (without impacting plant performance on emissions and efficiency) and thereby, increasing their marketability.« less

  14. THE CENTRAL ENGINES OF TWO UNUSUAL RADIO-INTERMEDIATE/QUIET ACTIVE GALACTIC NUCLEI: III Zw 2 AND PG 1407+265

    SciTech Connect (OSTI)

    Chen Liang; Cao Xinwu; Bai, J. M. E-mail: cxw@shao.ac.cn

    2012-04-01

    We use the accretion disk/corona+jet model to fit the multi-band spectral energy distributions (SEDs) of two unusual radio-intermediate/quiet quasars. It is found that the optical/UV emission of III Zw 2 is probably dominated by the emission from the accretion disk. The X-ray emission should be dominated by the radiation from the jet, while the contribution of the disk corona is negligible. The optical/UV component in the SED of PG 1407+265 can be well modeled as the emission from the accretion disk, while the IR component is attributed to the thermal radiation from the dust torus with an opening angle of {approx}50 Degree-Sign . If the X-ray continuum emission is dominated by the synchrotron emission of the jet, the source should be a 'high peak frequency blazar', which obviously deviates from the normal blazar sequence. The observed SED can also be fitted quite well by the accretion disk/corona model with the viscosity parameter {alpha} = 0.5. The spectrum of the accretion disk/corona in PG 1407+265 satisfies the weak-line quasar criterion suggested in Laor and Davis.

  15. Cold-Air-Pool Structure and Evolution in a Mountain Basin: Peter Sinks, Utah

    SciTech Connect (OSTI)

    Clements, Craig B.; Whiteman, Charles D.; Horel, John D.

    2003-06-01

    The evolution of potential temperature and wind structure during the buildup of nocturnal cold-air pools was investigated during clear, dry, September nights in Utah's Peter Sinks basin, a 1-km-diameter limestone sinkhole that holds the Utah minimum temperature record of -56 C. The evolution of cold-pool characteristics depended on the strength of prevailing flows above the basin. On an undisturbed day, a 30 C diurnal temperature range and a strong nocturnal potential temperature inversion (22 K in 100 m) were observed in the basin. Initially, downslope flows formed on the basin sidewalls. As a very strong potential temperature jump (17 K) developed at the top of the cold pool, however, the winds died within the basin and over the sidewalls. A persistent turbulent sublayer formed below the jump. Turbulent sensible heat flux on the basin floor became negligible shortly after sunset while the basin atmosphere continued to cool. Temperatures over the slopes, except for a 1 to 2-m-deep layer, became warmer than over the basin center at the same altitude. Cooling rates for the entire basin near sunset were comparable to the 90 W m-2 rate of loss of net longwave radiation at the basin floor, but these rates decreased to only a few watts per square meter by sunrise. This paper compares the observed cold-pool buildup in basins with inversion buildup in valleys.

  16. Ultra-lean combustion at high inlet temperatures

    SciTech Connect (OSTI)

    Anderson, D.N.

    1981-01-01

    Combustion at inlet-air temperatures of 1100 to 1250/sup 0/K was studied for application to advanced automotive gas turbine engines. Combustion was initiated by the hot environment, and therefore no external ignition source was used. Combustion was stabilized without a flameholder. The tests were performed in a 12-cm-diameter test section at a pressure of 2.5 x 10/sup 5/ Pa, with reference velocities of 32 to 60 m/s and at maximum combustion temperatures of 1350 to 1850/sup 0/K. Number 2 diesel fuel was injected by means of a multiple-source fuel injector. Unburned hydrocarbons emissions were negligible for all test conditions. Nitrogen oxides emissions were less than 1.9 g NO/sub 2//kg fuel for combustion temperatures below 1680/sup 0/K. Carbon monoxide emissions were less than 16 g CO/kg fuel for combustion temperatures greater than 1600/sup 0/K, inlet-air temperatures higher than 1150/sup 0/K, and residence times greater than 4.3 ms.

  17. Ammonia formation from NO reaction with surface hydroxyls on rutile TiO2 (110) - 11

    SciTech Connect (OSTI)

    Kim, Boseong; Kay, Bruce D.; Dohnalek, Zdenek; Kim, Yu Kwon

    2015-01-15

    The reaction of NO with hydroxylated rutile TiO2(110)-11 surface (h-TiO2) was investigated as a function of NO coverage using temperature-programmed desorption. Our results show that NO reaction with h-TiO2 leads to formation of NH3 which is observed to desorb at ~ 400 K. Interestingly, the amount of NH3 produced depends nonlinearly on the coverage of NO. The yield increases up to a saturation value of ~1.31013 NH3/cm2 at a NO dose of 51013 NO/cm2, but subsequently decreases at higher NO doses. Preadsorbed H2O is found to have a negligible effect on the NH3 desorption yield. Additionally, no NH3 is formed in the absence of surface hydroxyls (HObs) upon coadsorption of NO and H2O on a stoichiometric TiO2(110) (s-TiO2(110)). Based on these observations, we conclude that nitrogen from NO has a strong preference to react with HObs on the bridge-bonded oxygen rows (but not with H2O) to form NH3. The absolute NH3 yield is limited by competing reactions of HOb species with titanium-bound oxygen adatoms to form H2O. Our results provide new mechanistic insight about the interactions of NO with hydroxyl groups on TiO2(110) .

  18. Electronic structure of the heavy-fermion caged compound Ce3Pd20X6(X=Si,Ge) studied by density functional theory and photoelectron spectroscopy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yamaoka, Hitoshi; Schwier, Eike F.; Arita, Masashi; Shimada, Kenya; Tsujii, Naohito; Jarrige, Ignace; Jiang, Jian; Hayashi, Hirokazu; Iwasawa, Hideaki; Namatame, Hirofumi; et al

    2015-03-30

    The electronic structure of Ce₃Pd₂₀X₆ (X = Si, Ge) has been studied using detailed density functional theory (DFT) calculations and high-resolution photoelectron spectroscopy (PES) measurements. The orbital decomposition of the electronic structure by DFT calculations indicates that Ce atoms at the (8c) site surrounded by 16 Pd atoms have a more localized nature and a tendency to be magnetic. Ce atoms in the (4a) site surrounded by 12 Pd and 6 X atoms, on the other, show only a negligible magnetic moment. In the photoemission valence-band spectra we observe a strong f⁰ (Ce⁴⁺) component with a small fraction of f¹more »(Ce³⁺) component. The spectral weight of f¹ component near the Fermi level Ce₃Pd₂₀Si₆ is stronger than that for Ce₃Pd₂₀Ge₆ at the 4d-4f resonance, suggesting stronger c-f hybridization in the former. This may hint to the origin of the large electronic specific coefficient of Ce₃Pd₂₀Si₆ compared to Ce₃Pd₂₀Ge₆.« less

  19. Extending Higgs inflation with TeV scale new physics

    SciTech Connect (OSTI)

    He, Hong-Jian; Xianyu, Zhong-Zhi E-mail: xianyuzhongzhi@gmail.com

    2014-10-01

    Higgs inflation is among the most economical and predictive inflation models, although the original Higgs inflation requires tuning the Higgs or top mass away from its current experimental value by more than 2? deviations, and generally gives a negligible tensor-to-scalar ratio r?10{sup -3} (if away from the vicinity of critical point). In this work, we construct a minimal extension of Higgs inflation, by adding only two new weak-singlet particles at TeV scale, a vector-quark T and a real scalar S. The presence of singlets (T,S) significantly impact the renormalization group running of the Higgs boson self-coupling. With this, our model provides a wider range of the tensor-to-scalar ratio r=O(0.1)-O(10{sup -3}), consistent with the favored r values by either BICEP2 or Planck data, while keeping the successful prediction of the spectral index n{sub s}?0.96. It allows the Higgs and top masses to fully fit the collider measurements. We also discuss implications for searching the predicted TeV-scale vector-quark T and scalar S at the LHC and future high energy pp colliders.

  20. Evidence for the temperature dependence of phase transformation behavior of silicon at nanoscale

    SciTech Connect (OSTI)

    Mangalampalli S. R. N., Kiran; Tran, Tuan; Smillie, Lachlan; Haberl, Bianca; Subianto, D.; Williams, James S.; Bradby, Jodie E.

    2015-01-01

    This study uses the in-situ high-temperature nanoindentation coupled with electrical measurements to investigate the temperature dependence (25 to 200 C) of the phase transformation behavior of crystalline silicon (dc-Si) at the nanoscale. Along with in-situ indentation and electrical data, ex-situ characterizations such as Raman and cross-sectional transmission electron microscopy (XTEM) have been used to reveal the dominant mode of deformation under the indenter. In contrast to the previous studies, the dominant mode of deformation under the nanoindenter at elevated temperatures is not the dc-Si to metallic phase ( -Sn) transformation. Instead, XTEM images from 150 C indents reveal that the dominant mode of deformation is twinning along {111} planes. While the in-situ high-temperature electrical measurements show an increase in the current due to metallic phase formation up to 125 C, it is absent 150 C, revealing that the formation of the metallic phase is negligible in this regime. Thus, this work provides clear insight into the temperature dependent deformation mechanisms in dc-Si at the nanoscale.

  1. Control of the polarization of a vacuum-ultraviolet, high-gain, free-electron laser

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Allaria, Enrico; Diviacco, Bruno; Callegari, Carlo; Finetti, Paola; Mahieu, Benoît; Viefhaus, Jens; Zangrando, Marco; De Ninno, Giovanni; Lambert, Guillaume; Ferrari, Eugenio; et al

    2014-12-02

    The two single-pass, externally seeded free-electron lasers (FELs) of the FERMI user facility are designed around Apple-II-type undulators that can operate at arbitrary polarization in the vacuum ultraviolet-to-soft x-ray spectral range. Furthermore, within each FEL tuning range, any output wavelength and polarization can be set in less than a minute of routine operations. We report the first demonstration of the full output polarization capabilities of FERMI FEL-1 in a campaign of experiments where the wavelength and nominal polarization are set to a series of representative values, and the polarization of the emitted intense pulses is thoroughly characterized by three independentmore » instruments and methods, expressly developed for the task. The measured radiation polarization is consistently >90% and is not significantly spoiled by the transport optics; differing, relative transport losses for horizontal and vertical polarization become more prominent at longer wavelengths and lead to a non-negligible ellipticity for an originally circularly polarized state. The results from the different polarimeter setups validate each other, allow a cross-calibration of the instruments, and constitute a benchmark for user experiments.« less

  2. Highly Charged Ion (HCI) Modified Tunnel Junctions

    SciTech Connect (OSTI)

    Pomeroy, J. M.; Grube, H. [Atomic Physics Division, National Institute of Standards and Technology (NIST) 100 Bureau Dr., MS 8423, Gaithersburg, MD 20899-8423 (United States)

    2009-03-10

    The neutralization energy carried by highly charged ions (HCIs) provides an alternative method for localizing energy on a target's surface, producing features and modifying surfaces with fluences and kinetic energy damage that are negligible compared to singly ionized atoms. Since each HCI can deposit an enormous amount of energy into a small volume of the surface (e.g., Xe{sup 44+} delivers 51 keV of neutralization energy per HCI), each individual HCI's interaction with the target can produce a nanoscale feature. Many studies of HCI-surface features have characterized some basic principles of this unique ion-surface interaction, but the activity reported here has been focused on studying ensembles of HCI features in ultra-thin insulating films by fabricating multi-layer tunnel junction devices. The ultra-thin insulating barriers allow current to flow by tunneling, providing a very sensitive means of detecting changes in the barrier due to highly charged ion irradiation and, conversely, HCI modification provides a method of finely tuning the transparency of the tunnel junctions that spans several orders of magnitude for devices produced from a single process recipe. Systematic variation of junction bias, temperature, magnetic field and other parameters provides determination of the transport mechanism, defect densities, and magnetic properties of these nano-features and this novel approach to device fabrication.

  3. Cross-correlation measurement of quantum shot noise using homemade transimpedance amplifiers

    SciTech Connect (OSTI)

    Hashisaka, Masayuki Ota, Tomoaki; Yamagishi, Masakazu; Fujisawa, Toshimasa; Muraki, Koji

    2014-05-15

    We report a cross-correlation measurement system, based on a new approach, which can be used to measure shot noise in a mesoscopic conductor at milliKelvin temperatures. In contrast to other measurement systems in which high-speed low-noise voltage amplifiers are commonly used, our system employs homemade transimpedance amplifiers (TAs). The low input impedance of the TAs significantly reduces the crosstalk caused by unavoidable parasitic capacitance between wires. The TAs are designed to have a flat gain over a frequency band from 2 kHz to 1 MHz. Low-noise performance is attained by installing the TAs at a 4 K stage of a dilution refrigerator. Our system thus fulfills the technical requirements for cross-correlation measurements: low noise floor, high frequency band, and negligible crosstalk between two signal lines. Using our system, shot noise generated at a quantum point contact embedded in a quantum Hall system is measured. The good agreement between the obtained shot-noise data and theoretical predictions demonstrates the accuracy of the measurements.

  4. Absorptive separation of NO from dilute off-gas

    SciTech Connect (OSTI)

    Zapfel, W.; Marr, R.; Siebenhofer, M.

    1999-04-01

    With regard to its negligible absorption properties, the separation of nitrogen monoxide from dilute off-gas is limited to bench-scale experiments. Investigation has been centered on improving the rate of absorption by the use of complex-forming additives based on iron(II) compounds. Further efforts have been made to improve the separation efficiency by the use of reactive additives. Due to the low reactivity of nitrogen monoxide, these attempts did not succeed. The oxidation of moderately concentrated off-gas with ozone and the absorption of the so-formed nitrogen dioxide have been reported. Technical as well as economical considerations do not permit the application of the process to the treatment of dilute off-gas. The principle underlying this process led to the investigation of direct oxidation of the off-gas under electrical discharge followed by absorption with aqueous diamide solution. Temperature and moisture of the off-gas have been considered, in addition to various feed contents of nitrogen monoxide. The results of this investigation show that direct oxidation of nitrogen monoxide by corona discharge is possible. The rate of conversion increases with increasing gas velocity, accompanied by a decreasing specific energy consumption. Applied to tunnel off-gas purification, the direct oxidation route seems to offer promising technical boundaries as it is accompanied by efficient particle separation.

  5. Distributed resonance self-shielding using the equivalence principle

    SciTech Connect (OSTI)

    Altiparmakov, D.

    2012-07-01

    This paper presents an extension of the equivalence principle to allow distributed resonance self-shielding in a multi-region fuel configuration. Rational expansion of fuel-to-fuel collision probability is applied in order to establish equivalence between the actual fuel configuration and a homogeneous mixture of hydrogen and resonant absorber, which is a commonly used model to calculate library tables of resonance integrals. The main steps in derivation are given along with the basic physics assumptions on which the presented approach relies. The method has been implemented in the lattice code WIMS-AECL and routinely used for calculation of CANDU-type reactor lattices. Its capabilities are illustrated by comparison of WIMS-AECL and MCNP results of {sup 238}U resonance capture in a CANDU lattice cell. In order to determine optimal rational expansion of fuel-to-fuel collision probability, the calculations were carried out by varying the number of rational terms from 1 to 6. The results show that 4 terms are sufficient. The further increase of the number of terms affects the computing time, while the impact on accuracy is negligible. To illustrate the convergence of the results, the fuel subdivision is gradually refined varying the number of fuel pin subdivisions from 1 to 32 equal-area annuli. The results show very good agreement with the reference MCNP calculation. (authors)

  6. Sunna 535-nm photo-fluorescent film dosimeter response to different environmental conditions

    SciTech Connect (OSTI)

    Murphy, Mark K.; Kovacs, Andras; Mclaughlin, William L.; Miller, Steven D.); Puhl, James M.

    2003-12-01

    Evaluations on the influence of environmental variabilities on the red fluorescence component of the Sunna Model? photo-fluorescent dosimeter have previously been reported. This present paper describes the environmental effects on the response of the green fluorescence component of the same dosimeter, which is manufactured using the injection molding technique. The results presented include temperature, relative humidity, and light influences both during and after irradiation. The green fluorescence signal shows a significant dependence on irradiation temperature below room temperature at 1%/C. Above room temperature (approximately 24C to 60C), the irradiation temperature effect varies from -0.1-1.0%/C, depending on the absorbed dose level. For facilities with irradiation temperatures between 30-60C and absorbed dose levels above 10 kGy, irradiation temperature effects are minimal. Light-effects results indicate that the dosimeter is influenced by ultraviolet and blue wavelengths during irradiation as well as during the post-irradiation stabilization period (approx. 22 hours), requiring the use of light-tight packaging. Results also show that the dosimeter exhibits negligible effects from ambient moisture during and after irradiation when in the range of 33-95% relative humidity.

  7. Cladding burst behavior of Fe-based alloys under LOCA

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Terrani, Kurt A.; Dryepondt, Sebastien N.; Pint, Bruce A.; Massey, Caleb P.

    2015-12-17

    Burst behavior of austenitic and ferritic Fe-based alloy tubes has been examined under a simulated large break loss of coolant accident. Specifically, type 304 stainless steel (304SS) and oxidation resistant FeCrAl tubes were studied alongside Zircaloy-2 and Zircaloy-4 that are considered reference fuel cladding materials. Following the burst test, characterization of the cladding materials was carried out to gain insights regarding the integral burst behavior. Given the widespread availability of a comprehensive set of thermo-mechanical data at elevated temperatures for 304SS, a modeling framework was implemented to simulate the various processes that affect burst behavior in this Fe-based alloy. Themore » most important conclusion is that cladding ballooning due to creep is negligible for Fe-based alloys. Thus, unlike Zr-based alloys, cladding cross-sectional area remains largely unchanged up to the point of burst. Furthermore, for a given rod internal pressure, the temperature onset of burst in Fe-based alloys appears to be simply a function of the alloy's ultimate tensile strength, particularly at high rod internal pressures.« less

  8. Magnetocaloric effect in gadolinium-oxalate framework Gd{sub 2}(C{sub 2}O{sub 4}){sub 3}(H{sub 2}O){sub 6}⋅(0{sub ⋅}6H{sub 2}O)

    SciTech Connect (OSTI)

    Sibille, Romain Didelot, Emilie; Mazet, Thomas; Malaman, Bernard; François, Michel

    2014-12-01

    Magnetic refrigerants incorporating Gd{sup 3+} ions and light organic ligands offer a good balance between isolation of the magnetic centers and their density. We synthesized the framework material Gd{sub 2}(C{sub 2}O{sub 4}){sub 3}(H{sub 2}O){sub 6}⋅0.6H{sub 2}O by a hydrothermal route and characterized its structure. The honeycomb lattice of Gd{sup 3+} ions interlinked by oxalate ligands in the (a,c) plane ensures their decoupling in terms of magnetic exchange interactions. This is corroborated by magnetic measurements indicating negligible interactions between the Gd{sup 3+} ions in this material. The magnetocaloric effect was evaluated from isothermal magnetization measurements. The maximum entropy change −ΔS{sub M}{sup max} reaches 75.9 mJ cm{sup −3} K{sup −1} (around 2 K) for a moderate field change (2 T)

  9. NON-BAROTROPIC LINEAR ROSSBY WAVE INSTABILITY IN THREE-DIMENSIONAL DISKS

    SciTech Connect (OSTI)

    Lin, Min-Kai

    2013-03-10

    Astrophysical disks with localized radial structure, such as protoplanetary disks containing dead zones or gaps due to disk-planet interaction, may be subject to the non-axisymmetric Rossby wave instability (RWI) that leads to vortex formation. The linear instability has recently been demonstrated in three-dimensional (3D) barotropic disks. It is the purpose of this study to generalize the 3D linear problem to include an energy equation, thereby accounting for baroclinity in three dimensions. Linear stability calculations are presented for radially structured, vertically stratified, geometrically thin disks with non-uniform entropy distribution in both directions. Polytropic equilibria are considered but adiabatic perturbations assumed. The unperturbed disk has a localized radial density bump, making it susceptible to the RWI. The linearized fluid equations are solved numerically as a partial differential equation eigenvalue problem. Emphasis on the ease of method implementation is given. It is found that when the polytropic index is fixed and adiabatic index increased, non-uniform entropy has negligible effect on the RWI growth rate, but pressure and density perturbation magnitudes near a pressure enhancement increase away from the midplane. The associated meridional flow is also qualitatively changed from homentropic calculations. Meridional vortical motion is identified in the nonhomentropic linear solution, as well as in a nonlinear global hydrodynamic simulation of the RWI in an initially isothermal disk evolved adiabatically. Numerical results suggest that buoyancy forces play an important role in the internal flow of Rossby vortices.

  10. The structural and magnetic properties of Pr{sub 1−x}Er{sub x}Al{sub 2}

    SciTech Connect (OSTI)

    Pathak, Arjun K.; Gschneidner, K. A.; Pecharsky, V. K.

    2015-05-07

    We report on the effect of Er addition to PrAl{sub 2} on the lattice parameters, magnetic behavior, heat capacity, and magnetocaloric effect by using x-ray diffraction, magnetization, and heat capacity measurements. Unlike Pr{sub 0.6}Er{sub 0.4}Al{sub 2}, other alloys we studied in the pseudobinary (Pr{sub 1−x}Er{sub x})Al{sub 2} system do not exhibit a sharp peak in heat capacity with the application of magnetic field. Both the cubic lattice parameter and the Curie temperature decrease with increasing Er concentration. The nuclear specific heat coefficient decreases from 660 mJ K mol{sup −1} for x = 0.05 to a nearly negligible value for x = 0.95. The magnetic entropy and adiabatic temperature change varies from 2 to 4 J mol{sup −1} K{sup −1} and 2.5 to 5 K at ΔH = 20 kOe for x = 0.05 to 0.95, respectively. These values of the magnetocaloric effect are comparable to those of the other rare-earth dialuminides systems.

  11. In situ measurement of interfacial tension of Fe-S and Fe-P liquids under high pressure using X-ray radiography and tomography techniques

    SciTech Connect (OSTI)

    Terasakia, H; Urakawa, S; Funakoshi, K; Nishiyama, N; Wang, Y; Nishida, K; Sakamaki, T; Suzuki, A; Ohtani, E

    2009-09-14

    Interfacial tension is one of the most important properties of the liquid iron alloy that controls the core formation process in the early history of the Earth and planets. In this study, we made high-pressure X-ray radiography and micro-tomography measurements to determine the interfacial tension between liquid iron alloys and silicate melt using the sessile drop method. The measured interfacial tension of liquid Fe-S decreased significantly (802-112 mN/m) with increasing sulphur content (0-40 at%) at 1.5 GPa. In contrast, the phosphorus content of Fe had an almost negligible effect on the interfacial tension of liquid iron. These tendencies in the effects of light elements are consistent with those measured at ambient pressure. Our results suggest that the effect of sulphur content on the interfacial tension of liquid Fe-S (690 mN/m reduction with the addition of 40 at% S) is large compared with the effect of temperature (~273 mN/m reduction with an increase of 200 K). The three-dimensional structure of liquid Fe-S was obtained at ~2 GPa and 1373-1873 K with a high-pressure tomography technique. The Fe-S droplet was quite homogeneous when evaluated in a slice of the three-dimensional image.

  12. Radiography apparatus using gamma rays emitted by water activated by fusion neutrons

    SciTech Connect (OSTI)

    Smith, D.L.; Ikeda, Yujiro; Uno, Yoshitomo

    1995-12-31

    Radiography apparatus includes an arrangement for circulating pure water continuously between a location adjacent a source of energetic neutrons, such as a tritium target irradiated by a deuteron beam, and a remote location where radiographic analysis is conducted. Oxygen in the pure water is activated via the {sup 16}O(n,p) {sup 16}N reaction using 14-MeV neutrons produced at the neutron source via the {sup 3}H(d,n) {sup 4}He reaction. Essentially monoenergetic gamma rays at 6.129 (predominantly) and 7.115 MeV are produced by the 7.13-second {sup 16}N decay for use in radiographic analysis. The gamma rays have substantial penetrating power and are useful in determining the thickness of materials and elemental compositions, particularly for metals and high-atomic number materials. The characteristic decay half life of 7.13 seconds of the activated oxygen is sufficient to permit gamma ray generation at a remote location where the activated water is transported, while not presenting a chemical or radioactivity hazard because the radioactivity falls to negligible levels after 1--2 minutes.

  13. Draft Title 40 CFR 191 compliance certification application for the Waste Isolation Pilot Plant. Volume 8: Appendices HYDRO, IRD, LTM, NUTS, PAR, PMR, QAPD, RBP

    SciTech Connect (OSTI)

    1995-03-31

    Geohydrologic data have been collected in the Los Medanos area at the US Department of Energy`s proposed Waste Isolation Pilot Plant (WIPP) site in southeastern New Mexico since 1975 as part of a study evaluating the feasibility of storing defense-associated nuclear wastes within the bedded salt of the Salado Formation of Permian age. Drilling and hydrologic testing have identified three principal water-bearing zones above the Salado Formation and one below that could potentially transport wastes to the biosphere if the proposed facility were breached. The zones above the Salado are the contact between the Rustler and Salado Formations and the Culebra and Magenta Dolomite Members of the Rustler Formation of Permian age. The zone below the Salado Formation consists of channel sandstones in the Bell Canyon Formation of the Permian Delaware Mountain Group. Determinations of hydraulic gradients, directions of flow, and hydraulic properties were hindered because of the negligible permeability of the water-bearing zones. Special techniques in drilling, well completion, and hydraulic testing have been developed to determine the hydrologic characteristics of these water-producing zones.

  14. The GISMO two-millimeter deep field in GOODS-N

    SciTech Connect (OSTI)

    Staguhn, Johannes G.; Kovcs, Attila; Arendt, Richard G.; Benford, Dominic J.; Dwek, Eli; Fixsen, Dale J.; Jhabvala, Christine A.; Maher, Stephen F.; Miller, Timothy M.; Moseley, S. Harvey; Sharp, Elmer H.; Wollack, Edward J.; Decarli, Roberto; Walter, Fabian; Hilton, Gene C.; Irwin, Kent D.; Karim, Alexander; Leclercq, Samuel

    2014-07-20

    We present deep continuum observations using the GISMO camera at a wavelength of 2 mm centered on the Hubble Deep Field in the GOODS-N field. These are the first deep field observations ever obtained at this wavelength. The 1? sensitivity in the innermost ?4' of the 7' diameter map is ?135 ?Jy beam{sup 1}, a factor of three higher in flux/beam sensitivity than the deepest available SCUBA 850 ?m observations, and almost a factor of four higher in flux/beam sensitivity than the combined MAMBO/AzTEC 1.2 mm observations of this region. Our source extraction algorithm identifies 12 sources directly, and another 3 through correlation with known sources at 1.2 mm and 850 ?m. Five of the directly detected GISMO sources have counterparts in the MAMBO/AzTEC catalog, and four of those also have SCUBA counterparts. HDF850.1, one of the first blank-field detected submillimeter galaxies, is now detected at 2 mm. The median redshift of all sources with counterparts of known redshifts is z-tilde =2.910.94. Statistically, the detections are most likely real for five of the seven 2 mm sources without shorter wavelength counterparts, while the probability for none of them being real is negligible.

  15. Measured Black Carbon Deposition on the Sierra Nevada Snow Pack and Implication for Snow Pack Retreat

    SciTech Connect (OSTI)

    Hadley, O.L.; Corrigan, C.E.; Kirchstetter, T.W.; Cliff, S.S.; Ramanathan, V.

    2010-01-12

    Modeling studies show that the darkening of snow and ice by black carbon deposition is a major factor for the rapid disappearance of arctic sea ice, mountain glaciers and snow packs. This study provides one of the first direct measurements for the efficient removal of black carbon from the atmosphere by snow and its subsequent deposition to the snow packs of California. The early melting of the snow packs in the Sierras is one of the contributing factors to the severe water problems in California. BC concentrations in falling snow were measured at two mountain locations and in rain at a coastal site. All three stations reveal large BC concentrations in precipitation, ranging from 1.7 ng/g to 12.9 ng/g. The BC concentrations in the air after the snow fall were negligible suggesting an extremely efficient removal of BC by snow. The data suggest that below cloud scavenging, rather than ice nuclei, was the dominant source of BC in the snow. A five-year comparison of BC, dust, and total fine aerosol mass concentrations at multiple sites reveals that the measurements made at the sampling sites were representative of large scale deposition in the Sierra Nevada. The relative concentration of iron and calcium in the mountain aerosol indicates that one-quarter to one-third of the BC may have been transported from Asia.

  16. Device and method for electron beam heating of a high density plasma

    DOE Patents [OSTI]

    Thode, Lester E. (Los Alamos, NM)

    1981-01-01

    A device and method for relativistic electron beam heating of a high density plasma in a small localized region. A relativistic electron beam generator produces a high voltage electron beam which propagates along a vacuum drift tube and is modulated to initiate electron bunching within the beam. The beam is then directed through a low density gas chamber which provides isolation between the vacuum modulator and the relativistic electron beam target. The relativistic beam is then applied to a high density target plasma which typically comprises DT, DD, hydrogen boron or similar thermonuclear gas at a density of 10.sup.17 to 10.sup.20 electrons per cubic centimeter. The target plasma is ionized prior to application of the electron beam by means of a laser or other preionization source. Utilizing a relativistic electron beam with an individual particle energy exceeding 3 MeV, classical scattering by relativistic electrons passing through isolation foils is negligible. As a result, relativistic streaming instabilities are initiated within the high density target plasma causing the relativistic electron beam to efficiently deposit its energy into a small localized region within the high density plasma target.

  17. Manipulation of Zeeman coherence in solids at room temperature: Ramsey interference in the coherent-population-trapping spectrum of ruby

    SciTech Connect (OSTI)

    Kolesov, Roman; Scully, Marlan O.; Kocharovskaya, Olga [Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States)

    2006-11-15

    Coherent population trapping (CPT) in a three-level atomic medium pumped by two subsequent short optical pulses is considered under the condition of negligible population decay from the excited optical state. It is shown that the amount of atomic population transferred to the excited state by the combined action of the pulses strongly depends on the phase of the ground-state coherence excited by the first pulse at the arrival time of the second pulse. Oscillatory behavior of optical excitation efficiency on the time delay between the pulses is predicted. It is also shown that saturating optical pulses can produce population inversion in a resonantly pumped quasi-two-level system. A class of solid materials in which the predicted phenomena can be observed at room temperature is found. It includes some rare-earth and transition-metal doped dielectric crystals where Orbach relaxation between ground-state Zeeman states is suppressed: ruby, alexandrite, and several others. On the basis of the theoretical predictions, experimental observation of Ramsey fringes in CPT spectrum of ruby is reported.

  18. hhjj production at the LHC

    SciTech Connect (OSTI)

    Dolan, Matthew J.; Englert, Christoph; Greiner, Nicolas; Nordstrom, Karl; Spannowsky, Michael

    2015-08-25

    The search for di-Higgs production at the LHC in order to set limits on the Higgs trilinear coupling and constraints on new physics is one of the main motivations for the LHC high-luminosity phase. Recent experimental analyses suggest that such analyses will only be successful if information from a range of channels is included. We therefore investigate di-Higgs production in association with two hadronic jets and give a detailed discussion of both the gluon- and the weak boson-fusion (WBF) contributions, with a particular emphasis on the phenomenology with modified Higgs trilinear and quartic gauge couplings. We perform a detailed investigation of the full hadronic final state and find that hhjj production should add sensitivity to a di-Higgs search combination at the HL-LHC with 3 ab-1. Since the WBF and GF contributions are sensitive to different sources of physics beyond the Standard Model, we devise search strategies to disentangle and isolate these production modes. In addition, while gluon fusion remains non-negligible in WBF-type selections, sizeable new physics contributions to the latter can still be constrained. As an example of the latter point we investigate the sensitivity that can be obtained for a measurement of the quartic Higgs–gauge boson couplings.

  19. A Validation Study of Pin Heat Transfer for UO2 Fuel Based on the IFA-432 Experiments

    SciTech Connect (OSTI)

    Phillippe, Aaron M; Clarno, Kevin T; Banfield, James E; Ott, Larry J; Philip, Bobby; Berrill, Mark A; Sampath, Rahul S; Allu, Srikanth; Hamilton, Steven P

    2014-01-01

    The IFA-432 (Integrated Fuel Assessment) experiments from the International Fuel Performance Experiments (IFPE) database were designed to study the effects of gap size, fuel density, and fuel densification on fuel centerline temperature in light-water-reactor fuel. An evaluation of nuclear fuel pin heat transfer in the FRAPCON-3.4 and Exnihilo codes for uranium dioxide (UO$_2$) fuel systems was performed, with a focus on the densification stage (2.2 \\unitfrac{GWd}{MT(UO$_{2}$)}). In addition, sensitivity studies were performed to evaluate the effect of the radial power shape and approximations to the geometry to account for the thermocouple hole. The analysis demonstrated excellent agreement for rods 1, 2, 3, and 5 (varying gap thicknesses and density with traditional fuel), demonstrating the accuracy of the codes and their underlying material models for traditional fuel. For rod 6, which contained unstable fuel that densified an order of magnitude more than traditional, stable fuel, the magnitude of densification was over-predicted and the temperatures were outside of the experimental uncertainty. The radial power shape within the fuel was shown to significantly impact the predicted centerline temperatures, whereas modeling the fuel at the thermocouple location as either annular or solid was relatively negligible. This has provided an initial benchmarking of the pin heat transfer capability of Exnihilo for UO$_2$ fuel with respect to a well-validated nuclear fuel performance code.

  20. Does water dope carbon nanotubes?

    SciTech Connect (OSTI)

    Bell, Robert A.; Payne, Michael C.; Mostofi, Arash A.

    2014-10-28

    We calculate the long-range perturbation to the electronic charge density of carbon nanotubes (CNTs) as a result of the physisorption of a water molecule. We find that the dominant effect is a charge redistribution in the CNT due to polarisation caused by the dipole moment of the water molecule. The charge redistribution is found to occur over a length-scale greater than 30 , highlighting the need for large-scale simulations. By comparing our fully first-principles calculations to ones in which the perturbation due to a water molecule is treated using a classical electrostatic model, we estimate that the charge transfer between CNT and water is negligible (no more than 10{sup ?4}?e per water molecule). We therefore conclude that water does not significantly dope CNTs, a conclusion that is consistent with the poor alignment of the relevant energy levels of the water molecule and CNT. Previous calculations that suggest water n-dopes CNTs are likely due to the misinterpretation of Mulliken charge partitioning in small supercells.

  1. Controlling Wind Turbines for Secondary Frequency Regulation: An Analysis of AGC Capabilities Under New Performance Based Compensation Policy: Preprint

    SciTech Connect (OSTI)

    Aho, J.; Pao, L. Y.; Fleming, P.; Ela, E.

    2015-02-01

    As wind energy becomes a larger portion of the world's energy portfolio there has been an increased interest for wind turbines to control their active power output to provide ancillary services which support grid reliability. One of these ancillary services is the provision of frequency regulation, also referred to as secondary frequency control or automatic generation control (AGC), which is often procured through markets which recently adopted performance-based compensation. A wind turbine with a control system developed to provide active power ancillary services can be used to provide frequency regulation services. Simulations have been performed to determine the AGC tracking performance at various power schedule set-points, participation levels, and wind conditions. The performance metrics used in this study are based on those used by several system operators in the US. Another metric that is analyzed is the damage equivalent loads (DELs) on turbine structural components, though the impacts on the turbine electrical components are not considered. The results of these single-turbine simulations show that high performance scores can be achieved when there is sufficient wind resource available. The capability of a wind turbine to rapidly and accurately follow power commands allows for high performance even when tracking rapidly changing AGC signals. As the turbine de-rates to meet decreased power schedule set-points there is a reduction in the DELs, and the participation in frequency regulation has a negligible impact on these loads.

  2. Neutron scattering study on cathode LiMn{sub 2}O{sub 4} and solid electrolyte 5(Li{sub 2}O)(P{sub 2}O{sub 5})

    SciTech Connect (OSTI)

    Kartini, E. Putra, Teguh P. Jahya, A. K. Insani, A.; Adams, S.

    2014-09-30

    Neutron scattering is very important technique in order to investigate the energy storage materials such as lithium-ion battery. The unique advantages, neutron can see the light atoms such as Hydrogen, Lithium, and Oxygen, where those elements are negligible by other corresponding X-ray method. On the other hand, the energy storage materials, such as lithium ion battery is very important for the application in the electric vehicles, electronic devices or home appliances. The battery contains electrodes (anode and cathode), and the electrolyte materials. There are many challenging to improve the existing lithium ion battery materials, in order to increase their life time, cyclic ability and also its stability. One of the most scientific challenging is to investigate the crystal structure of both electrode and electrolyte, such as cathodes LiCoO{sub 2}, LiMn{sub 2}O{sub 4} and LiFePO{sub 4}, and solid electrolyte Li{sub 3}PO{sub 4}. Since all those battery materials contain Lithium ions and Oxygen, the used of neutron scattering techniques to study their structure and related properties are very important and indispensable. This article will review some works of investigating electrodes and electrolytes, LiMn{sub 2}O{sub 4} and 5(Li{sub 2}O)(P{sub 2}O{sub 5}), by using a high resolution powder diffraction (HRPD) at the multipurpose research reactor, RSG-Sywabessy of the National Nuclear Energy Agency (BATAN), Indonesia.

  3. Optimum Electron Distributions for Space Charge Dominated Beams in Photoinjectors

    SciTech Connect (OSTI)

    Limborg-Deprey, C.; Bolton, P.R.; /SLAC

    2006-06-15

    The optimum photo-electron distribution from the cathode of an RF photoinjector producing a space charge dominated beam is a uniform distribution contained in an ellipsoid. For such a bunch distribution, the space charge forces are linear and the emittance growth induced by those forces is totally reversible and consequently can be compensated. With the appropriate tuning of the emittance compensation optics, the emittance, at the end of photoinjector beamline, for an ellipsoidal laser pulse, would only have two contributions, the cathode emittance and the RF emittance. For the peak currents of 50A and 100 A required from the SBand and L-Band RF gun photoinjectors discussed here, the RF emittance contribution is negligible. If such an ellipsoidal photo-electron distribution were available, the emittance at the end of the beamline could be reduced to the cathode emittance. Its value would be reduced by more than 40% from that obtained using cylindrical shape laser pulses. This potentially dramatic improvement warrants review of the challenges associated with the production of ellipsoidal photo-electrons. We assume the photo-electrons emission time to be short enough that the ellipsoidal electron pulse shape will come directly from the laser pulse. We shift the challenge to ellipsoidal laser pulse shaping. To expose limiting technical issues, we consider the generation of ellipsoidal laser pulse shape in terms of three different concepts.

  4. Detecting Silent Data Corruption for Extreme-Scale Applications through Data Mining

    SciTech Connect (OSTI)

    Bautista-Gomez, Leonardo; Cappello, Franck

    2014-01-16

    Supercomputers allow scientists to study natural phenomena by means of computer simulations. Next-generation machines are expected to have more components and, at the same time, consume several times less energy per operation. These trends are pushing supercomputer construction to the limits of miniaturization and energy-saving strategies. Consequently, the number of soft errors is expected to increase dramatically in the coming years. While mechanisms are in place to correct or at least detect some soft errors, a significant percentage of those errors pass unnoticed by the hardware. Such silent errors are extremely damaging because they can make applications silently produce wrong results. In this work we propose a technique that leverages certain properties of high-performance computing applications in order to detect silent errors at the application level. Our technique detects corruption solely based on the behavior of the application datasets and is completely application-agnostic. We propose multiple corruption detectors, and we couple them to work together in a fashion transparent to the user. We demonstrate that this strategy can detect the majority of the corruptions, while incurring negligible overhead. We show that with the help of these detectors, applications can have up to 80% of coverage against data corruption.

  5. A groundwater flow and transport model of long-term radionuclide migration in central Frenchman flat, Nevada test site

    SciTech Connect (OSTI)

    Kwicklis, Edward Michael [Los Alamos National Laboratory; Becker, Naomi M [Los Alamos National Laboratory; Ruskauff, Gregory [NAVARRO-INTERA, LLC.; De Novio, Nicole [GOLDER AND ASSOC.; Wilborn, Bill [US DOE NNSA NSO

    2010-11-10

    A set of groundwater flow and transport models were created for the Central Testing Area of Frenchman Flat at the former Nevada Test Site to investigate the long-term consequences of a radionuclide migration experiment that was done between 1975 and 1990. In this experiment, radionuclide migration was induced from a small nuclear test conducted below the water table by pumping a well 91 m away. After radionuclides arrived at the pumping well, the contaminated effluent was discharged to an unlined ditch leading to a playa where it was expected to evaporate. However, recent data from a well near the ditch and results from detailed models of the experiment by LLNL personnel have convincingly demonstrated that radionuclides from the ditch eventually reached the water table some 220 m below land surface. The models presented in this paper combine aspects of these detailed models with concepts of basin-scale flow to estimate the likely extent of contamination resulting from this experiment over the next 1,000 years. The models demonstrate that because regulatory limits for radionuclide concentrations are exceeded only by tritium and the half-life of tritium is relatively short (12.3 years), the maximum extent of contaminated groundwater has or will soon be reached, after which time the contaminated plume will begin to shrink because of radioactive decay. The models also show that past and future groundwater pumping from water supply wells within Frenchman Flat basin will have negligible effects on the extent of the plume.

  6. Eolian cover sands: a sedimentologic model and paleoenvironmental implications

    SciTech Connect (OSTI)

    Lea, P.D.

    1985-01-01

    In periglacial areas, accumulations of eolian sand commonly form low-relief blankets without well-developed dunes. Internally, these sandsheet deposits exhibit subhorizontal lamination rather than high-angle cross-bedding. Such cover sands of late-Pleistocene age mantle extensive areas in northern Europe, but have been reported more rarely from North America. The processes by which cover sands, as opposed to dunes, accumulate have not yet been determined conclusively. Wind ripples and sand dunes do not form a continuum; flow separation and avalanching and negligible in the former and vital in the latter. Accretion of a sand patch into a mound sufficient to cause flow separation and dune growth requires a consistently available supply of loose sand. In cover-sand areas, sand may be immobilized prior to dune development by several factors: (1) a sparse vegetation cover, (2) moist ground conditions, (3) snow cover, and (4) a shallow permafrost table and/or an ice-cemented active layer. Detailed sedimentologic studies may allow discrimination among these various controls. The importance of the individual controlling factors can vary seasonally in a given deposit, as well as between deposits in different paleogeographic settings. However, all factors imply more mesic conditions than those associated with many dune deposits. The association of cover sands with paraboloid dunes is also consistent with somewhat moist conditions. The relatively mesic nature of cover sands controls their Pleistocene distribution; they become decreasingly important relative to dunes in maritime-to-continental transects across Alaska and northern Europe.

  7. Electronic coupling calculations with transition charges, dipoles, and quadrupoles derived from electrostatic potential fitting

    SciTech Connect (OSTI)

    Fujimoto, Kazuhiro J.

    2014-12-07

    A transition charge, dipole, and quadrupole from electrostatic potential (TrESP-CDQ) method for electronic coupling calculations is proposed. The TrESP method is based on the classical description of electronic Coulomb interaction between transition densities for individual molecules. In the original TrESP method, only the transition charge interactions were considered as the electronic coupling. In the present study, the TrESP method is extended to include the contributions from the transition dipoles and quadrupoles as well as the transition charges. Hence, the self-consistent transition density is employed in the ESP fitting procedure. To check the accuracy of the present approach, several test calculations are performed to a helium dimer, a methane dimer, and an ethylene dimer. As a result, the TrESP-CDQ method gives a much improved description of the electronic coupling, compared with the original TrESP method. The calculated results also show that the self-consistent treatment to the transition densities contributes significantly to the accuracy of the electronic coupling calculations. Based on the successful description of the electronic coupling, the contributions to the electronic coupling are also analyzed. This analysis clearly shows a negligible contribution of the transition charge interaction to the electronic coupling. Hence, the distribution of the transition density is found to strongly influence the magnitudes of the transition charges, dipoles, and quadrupoles. The present approach is useful for analyzing and understanding the mechanism of excitation-energy transfer.

  8. Relativistic structure, stability, and gravitational collapse of charged neutron stars

    SciTech Connect (OSTI)

    Ghezzi, Cristian R.

    2005-11-15

    Charged stars have the potential of becoming charged black holes or even naked singularities. We present a set of numerical solutions of the Tolman-Oppenheimer-Volkov equations that represents spherical charged compact stars in hydrostatic equilibrium. The stellar models obtained are evolved forward in time integrating the Einstein-Maxwell field equations. We assume an equation of state of a neutron gas at zero temperature. The charge distribution is taken as being proportional to the rest mass density distribution. The set of solutions present an unstable branch, even with charge-to-mass ratios arbitrarily close to the extremum case. We perform a direct check of the stability of the solutions under strong perturbations and for different values of the charge-to-mass ratio. The stars that are in the stable branch oscillate and do not collapse, while models in the unstable branch collapse directly to form black holes. Stars with a charge greater than or equal to the extreme value explode. When a charged star is suddenly discharged, it does not necessarily collapse to form a black hole. A nonlinear effect that gives rise to the formation of a shell of matter (in supermassive stars), is negligible in the present simulations. The results are in agreement with the third law of black hole thermodynamics and with the cosmic censorship conjecture.

  9. Multimodal Imaging of Alzheimer Pathophysiology in the Brain's Default Mode Network

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Shin, Jonghan; Kepe, Vladimir; Small, Gary W.; Phelps, Michael E.; Barrio, Jorge R.

    2011-01-01

    The spatial correlations between the brain's default mode network (DMN) and the brain regions known to develop pathophysiology in Alzheimer's disease (AD) have recently attracted much attention. In this paper, we compare results of different functional and structural imaging modalities, including MRI and PET, and highlight different patterns of anomalies observed within the DMN. Multitracer PET imaging in subjects with and without dementia has demonstrated that [C-11]PIB- and [F-18]FDDNP-binding patterns in patients with AD overlap within nodes of the brain's default network including the prefrontal, lateral parietal, lateral temporal, and posterior cingulate cortices, with the exception of the medial temporalmore » cortex (especially, the hippocampus) where significant discrepancy between increased [F-18]FDDNP binding and negligible [C-11]PIB-binding was observed. [F-18]FDDNP binding in the medial temporal cortex—a key constituent of the DMN—coincides with both the presence of amyloid and tau pathology, and also with cortical areas with maximal atrophy as demonstrated by T1-weighted MR imaging of AD patients.« less

  10. Ota City : characterizing output variability from 553 homes with residential PV systems on a distribution feeder.

    SciTech Connect (OSTI)

    Stein, Joshua S.; Miyamoto, Yusuke; Nakashima, Eichi; Lave, Matthew

    2011-11-01

    This report describes in-depth analysis of photovoltaic (PV) output variability in a high-penetration residential PV installation in the Pal Town neighborhood of Ota City, Japan. Pal Town is a unique test bed of high-penetration PV deployment. A total of 553 homes (approximately 80% of the neighborhood) have grid-connected PV totaling over 2 MW, and all are on a common distribution line. Power output at each house and irradiance at several locations were measured once per second in 2006 and 2007. Analysis of the Ota City data allowed for detailed characterization of distributed PV output variability and a better understanding of how variability scales spatially and temporally. For a highly variable test day, extreme power ramp rates (defined as the 99th percentile) were found to initially decrease with an increase in the number of houses at all timescales, but the reduction became negligible after a certain number of houses. Wavelet analysis resolved the variability reduction due to geographic diversity at various timescales, and the effect of geographic smoothing was found to be much more significant at shorter timescales.

  11. Unintentional F doping of SrTiO3(001) etched in HF acid-structure and electronic properties

    SciTech Connect (OSTI)

    Chambers, Scott A.; Droubay, Timothy C.; Capan, Cigdem; Sun, Guangyuan

    2012-02-01

    We show that the HF acid etch commonly used to prepare SrTiO3(001) for heteroepitaxial growth of complex oxides results in a non-negligible level of F doping within the terminal surface layer of TiO2. Using a combination of x-ray photoelectron spectroscopy and scanned angle x-ray photoelectron diffraction, we determine that on average ~ 13% of the O anions in the surface layer are replaced by F, but that F does not occupy O sites in deeper layers. Despite this perturbation to the surface, the Fermi level remains unpinned, and the surface-state density, which determines the amount of band bending, is driven by factors other than F doping. The presence of F at the STO surface is expected to result in lower electron mobilities at complex oxide heterojunctions involving STO substrates because of impurity scattering. Unintentional F doping can be substantially reduced by replacing the HF-etch step with a boil in deionized water, which in conjunction with an oxygen tube furnace anneal, leaves the surface flat and TiO2 terminated.

  12. Effect of Ligands on Characteristics of (CdSe)13 Quantum Dot

    SciTech Connect (OSTI)

    Gao, Yang; Zhou, Bo; Kang, Seung-gu; Xin, Minsi; Yang, Ping; Dai, Xing; Wang, Zhigang; Zhou, Ruhong

    2014-01-01

    The widespread applications of quantum dots (QDs) have spurred an increasing interest in the study of their coating ligands, which can not only protect the electronic structures of the central QDs, but also control their permeability through biological membranes with both size and shape. In this work, we have used density functional theory (DFT) to investigate the electronic structures of (CdSe)13 passivated by OPMe2(CH2)nMe ligands with different lengths and various numbers of branches (Me=methyl group, n = 0, 1-3). Our results show that the absorption peak in the ultraviolet-visible (UV-vis) spectra displays a clear blue-shift, on the scale of ~100 nm, upon the binding of ligands. Once the total number of ligands bound with (CdSe)13 reached a saturated number (9 or 10), no more blue-shift occurred in the absorption peak in the UV-vis spectra. On the other hand, the aliphatic chain length of ligands has a negligible effect on the optical properties of the QD core. Analyses of the bonding characteristics confirm that optical transitions are dominantly governed by the central QD core rather than the organic passivation. Interestingly, the density of states (DOS) share similar characteristics as vibrational spectra, even though there is no coordination vibration mode between the ligands and the central QD. These findings might provide insights on the material design for the passivation of quantum dots for biomedical applications.

  13. Gravitational wave background from Standard Model physics: qualitative features

    SciTech Connect (OSTI)

    Ghiglieri, J.; Laine, M.

    2015-07-16

    Because of physical processes ranging from microscopic particle collisions to macroscopic hydrodynamic fluctuations, any plasma in thermal equilibrium emits gravitational waves. For the largest wavelengths the emission rate is proportional to the shear viscosity of the plasma. In the Standard Model at T>160 GeV, the shear viscosity is dominated by the most weakly interacting particles, right-handed leptons, and is relatively large. We estimate the order of magnitude of the corresponding spectrum of gravitational waves. Even though at small frequencies (corresponding to the sub-Hz range relevant for planned observatories such as eLISA) this background is tiny compared with that from non-equilibrium sources, the total energy carried by the high-frequency part of the spectrum is non-negligible if the production continues for a long time. We suggest that this may constrain (weakly) the highest temperature of the radiation epoch. Observing the high-frequency part directly sets a very ambitious goal for future generations of GHz-range detectors.

  14. Symmetry breaking indication for supergravity inflation in light of the Planck 2015

    SciTech Connect (OSTI)

    Li, Tianjun; Li, Zhijin; Nanopoulos, Dimitri V.

    2015-09-01

    Supergravity (SUGRA) theories with exact global U(1) symmetry or shift symmetry in Kähler potential provide natural frameworks for inflation. However, quadratic inflation is disfavoured by the new results on primordial tensor fluctuations from the Planck Collaboration. To be consistent with the new Planck data, we point out that the explicit symmetry breaking is needed, and study these two SUGRA inflation in detail. For SUGRA inflation with global U(1) symmetry, the symmetry breaking term leads to a trigonometric modulation on inflaton potential. Coefficient of the U(1) symmetry breaking term is of order 10{sup −2}, which is sufficient large to improve the inflationary predictions while its higher order corrections are negligible. Such models predict sizeable tensor fluctuations and highly agree with the Planck results. In particular, the model with a linear U(1) symmetry breaking term predicts the tensor-to-scalar ratio around r∼0.01 and running spectral index α{sub s}∼−0.004, which comfortably fit with the Planck observations. For SUGRA inflation with breaking shift symmetry, the inflaton potential is modulated by an exponential factor. The modulated linear and quadratic models are consistent with the Planck observations. In both types of models the tensor-to-scalar ratio can be of order 10{sup −2}, which will be tested by the near future observations.

  15. Observations on the Optimality Tolerance in the CAISO 33% RPS Model

    SciTech Connect (OSTI)

    Yao, Y; Meyers, C; Schmidt, A; Smith, S; Streitz, F

    2011-09-22

    In 2008 Governor Schwarzenegger of California issued an executive order requiring that 33 percent of all electricity in the state in the year 2020 should come from renewable resources such as wind, solar, geothermal, biomass, and small hydroelectric facilities. This 33% renewable portfolio standard (RPS) was further codified and signed into law by Governor Brown in 2011. To assess the market impacts of such a requirement, the California Public Utilities Commission (CPUC) initiated a study to quantify the cost, risk, and timing of achieving a 33% RPS by 2020. The California Independent System Operator (CAISO) was contracted to manage this study. The production simulation model used in this study was developed using the PLEXOS software package, which allows energy planners to optimize long-term system planning decisions under a wide variety of system constraints. In this note we describe our observations on varying the optimality tolerance in the CAISO 33% RPS model. In particular, we observe that changing the optimality tolerance from .05% to .5% leads to solutions over 5 times faster, on average, producing very similar solutions with a negligible difference in overall distance from optimality.

  16. Results from intercropping fast-growing trees and food crops at Morogoro, Tanzania

    SciTech Connect (OSTI)

    Redhead, J.F.

    1992-12-31

    In Morogoro, Tanzania, agroforestry trials were set up to investigate intercropping with primarily eucalypt species. The climate in the region is very similar to Kolar, Karnataka State, India. Three crops-sorghum, bean and maize-were grown annually under Eucalyptus tereticornis at 2.5 m x 2.5 m for three years with a range of weeding practices. Plots that were intercropped with beans showed best results. Shading by the eucalypts after three years resulted in negligible crop yields in all treatments. Three tree spacings of E. camaldulensis (3 m x 3 m, 4 m x 4 m, and 5 m x 5 m) were combined with the intercropping of beans and maize. Beans gave satisfactory yields at all spacings, but the maize showed significantly depressed yields at 3 m x 3 m at 4 m x 4 m, but was similar to pure maize crop at 5 m x 5 m spacing. Overall the extra revenue from a food crop in the first and second year of tree growth increases the return from the land. The short rotation of fast growing trees depleted the soil of nutrients and, as with other crops, the fertility would have to be maintained by applying fertilizer.

  17. Construction and Test of a Novel Superconducting RF Electron gun

    SciTech Connect (OSTI)

    Bisognano, Joseph J.

    2014-04-16

    The University of Wisconsin-Madison has completed installation of a superconducting electron gun. Its concept was optimized to be the source for a CW free electron laser facility with multiple megahertz repetition rate end stations. This VHF superconducting configuration holds the promise of the highest performance for CW injectors. Initial commissioning efforts show that the cavity can achieve gradients of 35 MV/m at the cathode position. With the cathode inserted CW operation has been achieved at 20 MV/m with good control of microphonics, negligible dark current, and Q0 > 3×109 at 4 K. Bunch charges of ~100 pC have been delivered, and first simple beam measurements made. These preliminary results are very encouraging for production of 100s pC bunches with millimeter-milliradian or smaller normalized emittances. Plans are in place to carry out more definitive studies to establish the full capabilities. However, since the grant was not renewed, the electron gun is currently mothballed, and without supplemental fund the opportunity for further work will be lost.

  18. Effects of the proximity of Au nanoparticles on magnetic and transport properties of LSMO ultrathin layers

    SciTech Connect (OSTI)

    Brivio, S.; Magen Dominguez, Cesar; Sidorenko, A; Petti, D.; Cantoni, M.; Finazzi, M; Ciccacci, F; Renzi, R; Varela del Arco, Maria; Picozzi, S.; Bertacco, R.

    2010-01-01

    The effect of the proximity of Au nanoparticles on the transport and magnetic properties of ultrathin La2/3Sr1/3MnO3 (LSMO) films has been investigated. We find a huge increase of the resistivity of the manganite (by four orders of magnitude for a Au nominal thickness of 2 nm), which is accompanied by a strong decrease of the Curie temperature. A combined scanning transmission electron microscopy and electron energy loss spectroscopy (STEM-EELS) analysis shows that interfaces are coherent and atomically sharp, and that the structural quality is very high. On the other end, a strong reduction of the Mn oxidation state is seen upon Au capping. NMR data show a strong attenuation of the double exchange signal upon formation of Au nanoparticles. Ab-initio calculations indicate a negligible influence of Au on LSMO at an ideal interface, with the LSMO surface magnetic and electronic properties essentially unchanged upon creation of the Au/LSMO interface. In view of these calculations, the experimental results cannot be explained in terms of purely electrostatic effects induced by the proximity of a noble metal. Here we propose that the main driving force underlying the observed change in physical properties is the high reactivity of Au nanoparticles which can locally pump oxygen from the manganite, thus favouring a phase separation ensuing from O inhomogeneity which deteriorates the transport and electrical properties.

  19. Fermi-LAT γ-ray anisotropy and intensity explained by unresolved radio-loud active galactic nuclei

    SciTech Connect (OSTI)

    Mauro, Mattia Di; Cuoco, Alessandro; Donato, Fiorenza; Siegal-Gaskins, Jennifer M. E-mail: alessandro.cuoco@to.infn.it E-mail: jsg@tapir.caltech.edu

    2014-11-01

    Radio-loud active galactic nuclei (AGN) are expected to contribute substantially to both the intensity and anisotropy of the isotropic γ-ray background (IGRB). In turn, the measured properties of the IGRB can be used to constrain the characteristics of proposed contributing source classes. We consider individual subclasses of radio-loud AGN, including low-, intermediate-, and high-synchrotron-peaked BL Lacertae objects, flat-spectrum radio quasars, and misaligned AGN. Using updated models of the γ-ray luminosity functions of these populations, we evaluate the energy-dependent contribution of each source class to the intensity and anisotropy of the IGRB. We find that collectively radio-loud AGN can account for the entirety of the IGRB intensity and anisotropy as measured by the Fermi Large Area Telescope (LAT). Misaligned AGN provide the bulk of the measured intensity but a negligible contribution to the anisotropy, while high-synchrotron-peaked BL Lacertae objects provide the dominant contribution to the anisotropy. In anticipation of upcoming measurements with the Fermi-LAT and the forthcoming Cherenkov Telescope Array, we predict the anisotropy in the broader energy range that will be accessible to future observations.

  20. A first-principles study of Pt thin films on SrTiO{sub 3}(100): Support effects on CO adsorption

    SciTech Connect (OSTI)

    Yuk, Simuck F.; Asthagiri, Aravind

    2015-03-28

    Density functional theory was used to study CO adsorption on thin Pt metal films supported on SrO- and TiO{sub 2}-terminated SrTiO{sub 3}(100) surfaces. Regardless of substrate-termination, significant enhancement in CO binding occurred on the Pt monolayer compared to the bulk Pt(100) surface. We also observed CO-coverage dependent shifting of Pt atoms, influenced by the nature of underlying oxide atoms. These oxide-induced effects become negligible after depositing more than 2 monolayers of Pt. Evaluating the electronic structures of oxide-supported Pt showed that the interaction of filled Pt d{sub xz+yz} and empty Pt d{sub z{sup 2}} states with CO molecular orbitals can be directly related to CO adsorption on the Pt/SrTiO{sub 3}(100) surface. A hybrid d-band model is able to capture the CO adsorption trends for systems that do not show large lateral distortion except for the case of Pt adsorbed above the Sr atom on the SrO-termination. For this case, charge transfer from adjacent Pt atoms leads to a large filled d{sub z{sup 2}} peak below the Fermi level that weakens the Pt–CO σ bonding due to Pauli repulsion.

  1. Parallel Tensor Compression for Large-Scale Scientific Data.

    SciTech Connect (OSTI)

    Kolda, Tamara G.; Ballard, Grey; Austin, Woody Nathan

    2015-10-01

    As parallel computing trends towards the exascale, scientific data produced by high-fidelity simulations are growing increasingly massive. For instance, a simulation on a three-dimensional spatial grid with 512 points per dimension that tracks 64 variables per grid point for 128 time steps yields 8 TB of data. By viewing the data as a dense five way tensor, we can compute a Tucker decomposition to find inherent low-dimensional multilinear structure, achieving compression ratios of up to 10000 on real-world data sets with negligible loss in accuracy. So that we can operate on such massive data, we present the first-ever distributed memory parallel implementation for the Tucker decomposition, whose key computations correspond to parallel linear algebra operations, albeit with nonstandard data layouts. Our approach specifies a data distribution for tensors that avoids any tensor data redistribution, either locally or in parallel. We provide accompanying analysis of the computation and communication costs of the algorithms. To demonstrate the compression and accuracy of the method, we apply our approach to real-world data sets from combustion science simulations. We also provide detailed performance results, including parallel performance in both weak and strong scaling experiments.

  2. Dynamics of laser induced metal nanoparticle and pattern formation

    SciTech Connect (OSTI)

    Peláez, R. J. Kuhn, T.; Rodríguez, C. E.; Afonso, C. N.

    2015-02-09

    Discontinuous metal films are converted into either almost round, isolated, and randomly distributed nanoparticles (NPs) or fringed patterns of alternate non transformed film and NPs by exposure to single pulses (20 ns pulse duration and 193 nm wavelength) of homogeneous or modulated laser beam intensity. The dynamics of NPs and pattern formation is studied by measuring in real time the transmission and reflectivity of the sample upon homogeneous beam exposure and the intensity of the diffraction orders 0 and 1 in transmission configuration upon modulated beam exposure. The results show that laser irradiation induces melting of the metal either completely or at regions around intensity maxima sites for homogeneous and modulated beam exposure, respectively, within ≤10 ns. The aggregation and/or coalescence of the initially irregular metal nanostructures is triggered upon melting and continues after solidification (estimated to occur at ≤80 ns) for more than 1 μs. The present results demonstrate that real time transmission rather than reflectivity measurements is a valuable and easy-to-use tool for following the dynamics of NPs and pattern formation. They provide insights on the heat-driven processes occurring both in liquid and solid phases and allow controlling in-situ the process through the fluence. They also evidence that there is negligible lateral heat release in discontinuous films upon laser irradiation.

  3. THE STELLAR NUMBER DENSITY DISTRIBUTION IN THE LOCAL SOLAR NEIGHBORHOOD IS NORTH-SOUTH ASYMMETRIC

    SciTech Connect (OSTI)

    Yanny, Brian; Gardner, Susan

    2013-11-10

    We study the number density distribution of a sample of K and M dwarf stars, matched north and south of the Galactic plane within a distance of 2 kpc from the Sun, using observations from the Ninth Data Release of the Sloan Digital Sky Survey. We determine distances using the photometric parallax method, and in this context systematic effects exist which could potentially impact the determination of the number density profile with height from the Galactic planeand ultimately affect a number density north-south asymmetry. They include: (1) the calibration of the various photometric parallax relations, (2) the ability to separate dwarfs from giants in our sample, (3) the role of stellar population differences such as age and metallicity, (4) the ability to determine the offset of the Sun from the Galactic plane, and (5) the correction for reddening from dust in the Galactic plane, though our stars are at high Galactic latitudes. We find the various analyzed systematic effects to have a negligible impact on our observed asymmetry, and using a new and larger sample of stars we confirm and refine the earlier discovery of Widrow et al. of a significant Galactic north-south asymmetry in the stellar number density distribution.

  4. PACE-90 water and solute transport calculations for 0.01, 0.1, and 0. 5 mm/yr infiltration into Yucca Mountain; Yucca Mountain Site Characterization Project

    SciTech Connect (OSTI)

    Dykhuizen, R.C.; Eaton, R.R.; Hopkins, P.L.; Martinez, M.J.

    1991-12-01

    Numerical results are presented for the Performance Assessment Calculational Exercise (PACE-90). One- and two-dimensional water and solute transport are presented for steady infiltration into Yucca Mountain. Evenly distributed infiltration rates of 0.01, 0.1, and 0.5 mm/yr were considered. The calculations of solute transport show that significant amounts of radionuclides can reach the water table over 100,000 yr at the 0.5 mm/yr rate. For time periods less than 10,000 yr or infiltrations less than 0.1 mm/yr very little solute reaches the water table. The numerical simulations clearly demonstrate that multi-dimensional effects can result in significant decreases in the travel time of solute through the modeled domain. Dual continuum effects are shown to be negligible for the low steady state fluxes considered. However, material heterogeneities may cause local amplification of the flux level in multi-dimensional flows. These higher flux levels may then require modeling of a dual continuum porous medium.

  5. Measurement of the Top Quark Mass in the Lepton+Jets Channel Using the Lepton Transverse Momentum

    SciTech Connect (OSTI)

    Aaltonen, T.; Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Apresyan, A.; /Purdue U. /Waseda U. /Dubna, JINR

    2011-01-01

    This letter reports a measurement of the top quark mass, M{sub top}, in data from p{bar p} collisions at {radical}s = 1.96 TeV corresponding to 2.7 fb{sup -1} of integrated luminosity at the Fermilab Tevatron using the CDF II detector. Events with the lepton+jets topology are selected. An unbinned likelihood is constructed based on the dependence of the lepton transverse momentum, P{sub T}, on M{sub top}. A maximum likelihood fit to the data yields a measured mass M{sub top} = 176.9 {+-} 8.0{sub stat} {+-} 2.7{sub syst} GeV/c{sup 2}. In this measurement, the contribution by the jet energy scale uncertainty to the systematic error is negligible. The result provides an important consistency test for other M{sub top} measurements where explicit use of the jet energy is made for deriving the top quark mass.

  6. On the relationship among cloud turbulence, droplet formation and drizzle as viewed by Doppler radar, microwave radiometer and lidar

    SciTech Connect (OSTI)

    Feingold, G.; Frisch, A.S.; Cotton, W.R.

    1999-09-01

    Cloud radar, microwave radiometer, and lidar remote sensing data acquired during the Atlantic Stratocumulus Transition Experiment (ASTEX) are analyzed to address the relationship between (1) drop number concentration and cloud turbulence as represented by vertical velocity and vertical velocity variance and (2) drizzle formation and cloud turbulence. Six cases, each of about 12 hours duration, are examined; three of these cases are characteristic of nondrizzling boundary layers and three of drizzling boundary layers. In all cases, microphysical retrievals are only performed when drizzle is negligible (radar reflectivity{lt}{minus}17dBZ). It is shown that for the cases examined, there is, in general, no correlation between drop concentration and cloud base updraft strength, although for two of the nondrizzling cases exhibiting more classical stratocumulus features, these two parameters are correlated. On drizzling days, drop concentration and cloud-base vertical velocity were either not correlated or negatively correlated. There is a significant positive correlation between drop concentration and mean in-cloud vertical velocity variance for both nondrizzling boundary layers (correlation coefficient r=0.45) and boundary layers that have experienced drizzle (r=0.38). In general, there is a high correlation (r{gt}0.5) between radar reflectivity and in-cloud vertical velocity variance, although one of the boundary layers that experienced drizzle exhibited a negative correlation between these parameters. However, in the subcloud region, all boundary layers that experienced drizzle exhibit a negative correlation between radar reflectivity and vertical velocity variance. {copyright} 1999 American Geophysical Union

  7. Turbine-scale wind field measurements using dual-Doppler lidar

    SciTech Connect (OSTI)

    Newsom, Rob K.; Berg, Larry K.; Shaw, William J.; Fischer, Marc

    2015-02-01

    Spatially resolved measurements of micro-scale winds are retrieved using scanning dual-Doppler lidar, and validated against independent in situ wind measurements. Data for this study were obtained during a month-long field campaign conducted at a site in north-central Oklahoma in November of 2010. Observational platforms include one heavily instrumented 60-m meteorological tower and two scanning coherent Doppler lidars. The lidars were configured to perform coordinated dual-Doppler scans surrounding the 60-m tower, and the resulting radial velocity observations were processed to retrieve the 3-component velocity vector field on surfaces defined by the intersecting scan planes. Raw radial velocity measurements from the lidars were calibrated by direct comparison to a sonic anemometer located at the 60 m level on the tower. Wind retrievals were performed using both calibrated and uncalibrated measurements, and validated against the 60-m sonic anemometer observations. Retrievals using uncalibrated radial velocity data show a significant slow bias in the wind speed of about 14%; whereas the retrievals using the calibrated data show a much smaller slow bias of 1.2%. Retrievals using either the calibrated or uncalibrated data exhibit negligible bias in the wind direction (<0.2o), and excellent correlation in the wind speeds (>0.96).

  8. On the dissolution of iridium by aluminum.

    SciTech Connect (OSTI)

    Hewson, John C.

    2009-08-01

    The potential for liquid aluminum to dissolve an iridium solid is examined. Substantial uncertainties exist in material properties, and the available data for the iridium solubility and iridium diffusivity are discussed. The dissolution rate is expressed in terms of the regression velocity of the solid iridium when exposed to the solvent (aluminum). The temperature has the strongest influence in the dissolution rate. This dependence comes primarily from the solubility of iridium in aluminum and secondarily from the temperature dependence of the diffusion coefficient. This dissolution mass flux is geometry dependent and results are provided for simplified geometries at constant temperatures. For situations where there is negligible convective flow, simple time-dependent diffusion solutions are provided. Correlations for mass transfer are also given for natural convection and forced convection. These estimates suggest that dissolution of iridium can be significant for temperatures well below the melting temperature of iridium, but the uncertainties in actual rates are large because of uncertainties in the physical parameters and in the details of the relevant geometries.

  9. Factors influencing the transport of actinides in the groundwater environment. Final report

    SciTech Connect (OSTI)

    Sheppard, J.C.; Kittrick, J.A.

    1983-07-31

    This report summarizes investigations of factors that significantly influence the transport of actinide cations in the groundwater environment. Briefly, measurements of diffusion coefficients for Am(III), Cm(III), and Np(V) in moist US soils indicated that diffusion is negligible compared to mass transport in flowing groundwater. Diffusion coefficients do, however, indicate that, in the absence of flowing water, actinide elements will migrate only a few centimeters in a thousand years. The remaining investigations were devoted to the determination of distribution ratios (K/sub d/s) for representative US soils, factors influencing them, and chemical and physical processes related to transport of actinides in groundwaters. The computer code GARD was modified to include complex formation to test the importance of humic acid complexing on the rate of transport of actinides in groundwaters. Use of the formation constant and a range of humic acid, even at rather low concentrations of 10/sup -5/ to 10/sup -6/ molar, significantly increases the actinide transport rate in a flowing aquifer. These computer calculations show that any strong complexing agent will have a similar effect on actinide transport in the groundwater environment. 32 references, 9 figures.

  10. Theoretical Study of Trimethylacetic Acid Adsorption on CeO 2 (111) Surface

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Weina; Thevuthasan, S.; Wang, Wenliang; Yang, Ping

    2016-01-11

    We investigated trimethylacetic acid (TMAA) adsorption on stoichiometric and oxygen-deficient CeO2(111) surfaces using density functional theory that accounts for the on-site Coulomb interaction via a Hubbard term (DFT+U) and long-range dispersion correction. Both the molecular state and dissociative state (TMAA → TMA– + H+) were identified on stoichiometric and oxygen-deficient CeO2(111) surfaces. For the stoichiometric surface, two thermodynamically favorable configurations with adsorption energies of the order of -30 kcal/mol are identified; one is a molecule adsorption state, and the other one is a dissociative state. For the oxygen-deficient surface, dissociative states are more favorable than molecular states. Moreover, the mostmore » favorable configuration is the dissociative adsorption of TMAA with the adsorption energy of the order of -77 kcal/mol. The dissociated TMA moiety takes the position of oxygen vacancy, forming three Ce–O bonds. The signature vibrational frequencies for these thermodynamically stable structures are reported as well as their electronic structures. The effects of long-range dispersion interactions are found to be negligible for geometries but important for adsorption energies.« less

  11. Rate dependence of swelling in lithium-ion cells

    SciTech Connect (OSTI)

    Oh, KY; Siegel, JB; Secondo, L; Kim, SU; Samad, NA; Qin, JW; Anderson, D; Garikipati, K; Knobloch, A; Epureanu, BI; Monroe, CW; Stefanopoulou, A

    2014-12-01

    Swelling of a commercial 5 Ah lithium-ion cell with a nickel/manganese/cobalt-oxide cathode is investigated as a function of the charge state and the charge/discharge rate. In combination with sensitive displacement measurements, knowledge of the electrode configuration within this prismatic cell's interior allows macroscopic deformations of the casing to be correlated to electrochemical and mechanical transformations in individual anode/separator/cathode layers. Thermal expansion and interior charge state are both found to cause significant swelling. At low rates, where thermal expansion is negligible, the electrode sandwich dilates by as much as 1.5% as the charge state swings from 0% to 100% because of lithium-ion intercalation. At high rates a comparably large residual swelling was observed at the end of discharge. Thermal expansion caused by joule heating at high discharge rate results in battery swelling. The changes in displacement with respect to capacity at low rate correlate well with the potential changes known to accompany phase transitions in the electrode materials. Although the potential response changes minimally with the C-rate, the extent of swelling varies significantly, suggesting that measurements of swelling may provide a sensitive gauge for characterizing dynamic operating states. (C) 2014 Elsevier B.V. All rights reserved.

  12. Large area atmospheric-pressure plasma jet

    DOE Patents [OSTI]

    Selwyn, Gary S. (Los Alamos, NM); Henins, Ivars (Los Alamos, NM); Babayan, Steve E. (Huntington Beach, CA); Hicks, Robert F. (Los Angeles, CA)

    2001-01-01

    Large area atmospheric-pressure plasma jet. A plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two planar, parallel electrodes are employed to generate a plasma in the volume therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly spacing the rf-powered electrode. Because of the atmospheric pressure operation, there is a negligible density of ions surviving for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike the situation for low-pressure plasma sources and conventional plasma processing methods.

  13. Space-time contours to treat intense field-dressed molecular states

    SciTech Connect (OSTI)

    Paul, Amit K.; Adhikari, Satrajit; Baer, Michael

    2010-01-21

    In this article we consider a molecular system exposed to an intense short-pulsed external field. It is a continuation of a previous publication [A. K. Paul, S. Adhikari, D. Mukhopadhyay et al., J. Phys. Chem. A 113, 7331 (2009)] in which a theory is presented that treats quantum effects due to nonclassical photon states (known also as Fock states). Since these states became recently a subject of intense experimental efforts we thought that they can be treated properly within the existing quantum formulation of dynamical processes. This was achieved by incorporating them in the Born-Oppenheimer (BO) treatment with time-dependent coefficients. The extension of the BO treatment to include the Fock states results in a formidable enhancement in numerical efforts expressed, in particular, in a significant increase in CPU time. In the present article we discuss an approach that yields an efficient and reliable approximation with only negligible losses in accuracy. The approximation is tested in detail for the dissociation process of H{sub 2}{sup +} as caused by a laser field.

  14. Translational and internal energy distributions of methyl and hydroxyl radicals produced by 157 nm photodissociation of amorphous solid methanol

    SciTech Connect (OSTI)

    Hama, Tetsuya; Yokoyama, Masaaki; Yabushita, Akihiro; Kawasaki, Masahiro; Wickramasinghe, Piyumie; Guo Wei; Loock, Hans-Peter; Ashfold, Michael N. R.; Western, Colin M.

    2009-12-14

    Methanol is typically observed within water-rich interstellar ices and is a source of interstellar organic species. Following the 157 nm photoexcitation of solid methanol at 90 K, desorbed CH{sub 3}(v=0) and OH(v=0,1) radicals have been observed in situ, near the solid surface, using resonance-enhanced multiphoton ionization (REMPI) detection methods. Time-of-flight and rotationally resolved REMPI spectra of the desorbed species were measured, and the respective fragment internal energy and kinetic energy distributions were obtained. Photoproduction mechanisms for CH{sub 3} and OH radicals from solid methanol are discussed. The formation of O({sup 1}D and {sup 3}P) atoms and H{sub 2}O was investigated, but the yield of these species was found to be negligible. CH{sub 3} products arising following the photoexcitation of water-methanol mixed ice showed similar kinetic and internal energy distributions to those from neat methanol ice.

  15. Effect of particles attachment to multi-sized dust grains present in electrostatic sheaths of discharge plasmas

    SciTech Connect (OSTI)

    Zaham, B.; Tahraoui, A. Chekour, S.; Benlemdjaldi, D.

    2014-12-15

    The loss of electrons and ions due to their attachment to a Gauss-distributed sizes of dust grains present in electrostatic sheaths of discharge plasmas is investigated. A uni-dimensional, unmagnetized, and stationary multi-fluid model is proposed. Forces acting on the dust grain along with its charge are self-consistently calculated, within the limits of the orbit motion limited model. The dynamic analysis of dust grains shows that the contribution of the neutral drag force in the net force acting on the dust grain is negligible, whereas the contribution of the gravity force is found considerable only for micrometer particles. The dust grains trapping is only possible when the electrostatic force is balanced by the ion drag and the gravity forces. This trapping occurs for a limited radius interval of micrometer dust grains, which is around the most probable dust grain radius. The effect of electron temperature and ion density at the sheath edge is also discussed. It is shown that the attachment of particles reduces considerably the sheath thickness and induces dust grain deceleration. The increase of the lower limit as well as the upper limit of the dust radius reduces also the sheath thickness.

  16. Significant Silica Solubility in Geothermal Steam

    SciTech Connect (OSTI)

    James, Russell

    1986-01-21

    Although it is widely believed that silica solubility in low pressure (5 to 10 bar) geothermal steam is negligible, when one takes into account steam flows exceeding 10 million tonnes a year--at Wairakei, for instance--it is found that the amount transmitted in the vapor has the potential to give significant deposits on turbine nozzles and blades. A 150 MWe power station, when based on flows from a hot water reservoir at (a) 250 C or (b) 315 C, and with separator pressures of 6 bar, is found to carry about 100 and 200 kg/year respectively in the steam phase. In the case of a similar sized station exploiting a dry steam reservoir such as The Geysers, equivalent silica flows are obtained, dissolved in steam and carried as dust--the latter as solid particles precipitating from the vapor en route from source to turbine, and not preexisting in the formations as is commonly considered. Choking or coating of subterranean rock near such dry steam wells due to exsolving silica, may be the principal cause of declining steam discharge under production. Silica from completely dry or superheated steam can also seal the cap and sides of steam reservoirs when expanding below the criticus temperature (236 C) in a way previously thought possible only by hot water or wet steam.

  17. Hydroelectric power in Hawaii: a reconnaissance survey

    SciTech Connect (OSTI)

    1981-02-01

    The major conclusion of this study is that hydropower resources in the State of Hawaii are substantial, and they offer the potential for major increases in hydropower generating capacity. Hydropower resources on all islands total about 50 megawatts of potential generating capacity. Combined with the 18 megawatts of existing hydropower capacity, hydropower resources potentially could generate about 307 million kilowatt-hours of electric energy annually. This represents about 28% of the present combined electricity needs of the Neighbor Islands - Kauai, Molokai, Maui, and the Big Island. Hydropower resources on Kauai equal 72% of that island's electricity needs; on Molokai, 40%; on the Big Island, 20%; and on Maui, 18%. The island of Oahu, however, has only small hydropower resources, and could only generate a negligible portion of its electricity needs from this energy source. Existing and future (potential) hydropower capacities are summarized, and annual outputs for each island are estimated. Future hydropower facilities are subdivided into two categories, which show how much of the potential capacity is being actively considered for development, and how much is only tentatively proposed at the time.

  18. Hydroelectric power in Hawaii. A report on the statewide survey of potential hydroelectric sites

    SciTech Connect (OSTI)

    Beck, C. A.

    1981-02-01

    An assessment was made of the hydropower potential in Hawaii. The major conclusion of this study is that hydropower resources in the State of Hawaii are substantial, and they offer the potential for major increases in hydropower generating capacity. Hydropower resources on all islands total about 50 MW of potential generating capacity. Combined with the 18 MW of existing hydropower capacity, hydropower resources potentially could generate about 307 million kWh of electric energy annually. This represents about 28% of the present combined electricity needs of the Neighbor Islands, Kauai, Molokai, Maui, and the Big Island. Hydropower resources on Kauai equal 72% of that island's electricity needs; on Molokai, 40%, on the Big Island, 20%; and on Maui, 18%. The island of Oahu, however, has only small hydropower resources, and could only generate a negligible portion of its electricity needs from this energy source. A summary of existing and future (potential) hydropower capacities and estimated annual outputs for each island is presented. How much of the potential capacity is being actively considered for development and how much is only tentatively proposed at the time is indicated. The economics of hydropower at specific sites were analyzed. The major conclusion of this analysis is that hydropower development costs vary widely among the different sites, but that generally the cost of hydroelectric power is either less than or comparable to the cost of oil-fired power.

  19. Lensing reconstruction from a patchwork of polarization maps

    SciTech Connect (OSTI)

    Namikawa, Toshiya; Nagata, Ryo E-mail: rnagata@post.kek.jp

    2014-09-01

    The lensing signals involved in CMB polarization maps have already been measured with ground-based experiments such as SPTpol and POLARBEAR, and would become important as a probe of cosmological and astrophysical issues in the near future. Sizes of polarization maps from ground-based experiments are, however, limited by contamination of long wavelength modes of observational noise. To further extract the lensing signals, we explore feasibility of measuring lensing signals from a collection of small sky maps each of which is observed separately by a ground-based large telescope, i.e., lensing reconstruction from a patchwork map of large sky coverage organized from small sky patches. We show that, although the B-mode power spectrum obtained from the patchwork map is biased due to baseline uncertainty, bias on the lensing potential would be negligible if the B-mode on scales larger than the blowup scale of 1/f noise is removed in the lensing reconstruction. As examples of cosmological applications, we also show 1) the cross-correlations between the reconstructed lensing potential and full-sky temperature/polarization maps from satellite missions such as PLANCK and LiteBIRD, and 2) the use of the reconstructed potential for delensing B-mode polarization of LiteBIRD observation.

  20. Analysis of core damage frequency from internal events: Peach Bottom, Unit 2

    SciTech Connect (OSTI)

    Kolaczkowski, A.M.; Lambright, J.A.; Ferrell, W.L.; Cathey, N.G.; Najafi, B.; Harper, F.T.

    1986-10-01

    This document contains the internal event initiated accident sequence analyses for Peach Bottom, Unit 2; one of the reference plants being examined as part of the NUREG-1150 effort by the Nuclear Regulatory Commission. NUREG-1150 will document the risk of a selected group of nuclear power plants. As part of that work, this report contains the overall core damage frequency estimate for Peach Bottom, Unit 2, and the accompanying plant damage state frequencies. Sensitivity and uncertainty analyses provided additional insights regarding the dominant contributors to the Peach Bottom core damage frequency estimate. The mean core damage frequency at Peach Bottom was calculated to be 8.2E-6. Station blackout type accidents (loss of all ac power) were found to dominate the overall results. Anticipated Transient Without Scram accidents were also found to be non-negligible contributors. The numerical results are largely driven by common mode failure probability estimates and to some extent, human error. Because of significant data and analysis uncertainties in these two areas (important, for instance, to the most dominant scenario in this study), it is recommended that the results of the uncertainty and sensitivity analyses be considered before any actions are taken based on this analysis.

  1. Dependence of inverse-spin Hall effect and spin-rectified voltage on tantalum thickness in Ta/CoFeB bilayer structure

    SciTech Connect (OSTI)

    Kim, Sang-Il; Seo, Min-Su; Park, Seung-Young; Kim, Dong-Jun; Park, Byong-Guk

    2015-01-19

    Ta-layer thickness (t{sub Ta}) dependence of the measured DC voltage V from the inverse-spin Hall effect (ISHE) in Ta/CoFeB bilayer structure is experimentally investigated using the ferromagnetic resonance in the TE{sub 011} resonant cavity. The ISHE signals excluding the spin-rectified effect (SRE) were separated from the fitted curve of V against t{sub Ta}. For t{sub Ta} ≈ λ{sub Ta} (Ta-spin diffusion length = 2.7 nm), the deviation in ISHE voltage V{sub ISH} between the experimental and theoretical values is significantly increased because of the large SRE contribution, which also results in a large deviation in the spin Hall angle θ{sub SH} (from 10% to 40%). However, when t{sub Ta} ≫ λ{sub Ta}, the V{sub ISH} values are consistent with theoretical values because the SRE terms become negligible, which subsequently improves the accuracy of the obtained θ{sub SH} within 4% deviation. The results will provide an outline for an accurate estimation of the θ{sub SH} for materials with small λ value, which would be useful for utilizing the spin Hall effect in a 3-terminal spintronic devices in which magnetization can be controlled by in-plane current.

  2. COUNTER-ROTATION IN RELATIVISTIC MAGNETOHYDRODYNAMIC JETS

    SciTech Connect (OSTI)

    Cayatte, V.; Sauty, C.; Vlahakis, N.; Tsinganos, K.; Matsakos, T.; Lima, J. J. G.

    2014-06-10

    Young stellar object observations suggest that some jets rotate in the opposite direction with respect to their disk. In a recent study, Sauty et al. showed that this does not contradict the magnetocentrifugal mechanism that is believed to launch such outflows. Motion signatures that are transverse to the jet axis, in two opposite directions, have recently been measured in M87. One possible interpretation of this motion is that of counter-rotating knots. Here, we extend our previous analytical derivation of counter-rotation to relativistic jets, demonstrating that counter-rotation can indeed take place under rather general conditions. We show that both the magnetic field and a non-negligible enthalpy are necessary at the origin of counter-rotating outflows, and that the effect is associated with a transfer of energy flux from the matter to the electromagnetic field. This can be realized in three cases: if a decreasing enthalpy causes an increase of the Poynting flux, if the flow decelerates, or if strong gradients of the magnetic field are present. An illustration of the involved mechanism is given by an example of a relativistic magnetohydrodynamic jet simulation.

  3. Tomographic imaging system for measuring impurity line emission in a field-reversed configuration

    SciTech Connect (OSTI)

    Roche, T.; Heidbrink, W. W.; McWilliams, R.; Bolte, N.; Garate, E.; Wessel, F.

    2012-10-15

    A 16 chord optical tomography system has been developed and implemented in the flux coil generated-field reversed configuration (FRC). The chords are arranged in two fans of eight, which cover {approx}35% of the vessel area at the midplane. Each illuminate separate photomultiplier tubes (PMTs) which are fitted with narrow band-pass filters. In this case, filters are centered at 434.8 nm to measure emission from singly ionized argon. PMT crosstalk is negligible. Background noise due to electron radiation and H{sub {gamma}} line radiation is <10% of argon emission. The spatial resolution of the reconstruction is 1.5 cm. Argon is introduced using a puff valve and tube designed to impart the gas into the system as the FRC is forming. Reconstruction of experimental data results in time-dependent, 2D emissivity profiles of the impurity ions. Analysis of these data show radial, cross-field diffusion to be in the range of 10-10{sup 3} m{sup 2}/s during FRC equilibrium.

  4. Activation of Air and Utilities in the National Ignition Facility

    SciTech Connect (OSTI)

    Khater, H; Pohl, B; Brererton, S

    2010-04-08

    Detailed 3-D modeling of the NIF facility is developed to accurately simulate the radiation environment within the NIF. Neutrons streaming outside the NIF Target Chamber will activate the air present inside the Target Bay and the Ar gas inside the laser tubes. Smaller levels of activity are also generated in the Switchyard air and in the Ar portion of the SY laser beam path. The impact of neutron activation of utilities located inside the Target Bay is analyzed for variety of shot types. The impact of activating TB utilities on dose received by maintenance personnel post-shot is analyzed. The current NIF facility model includes all important features of the Target Chamber, shielding system, and building configuration. Flow of activated air from the Target Bay is controlled by the HVAC system. The amount of activated Target Bay air released through the stack is very small and does not pose significant hazard to personnel or the environment. Activation of Switchyard air is negligible. Activation of Target Bay utilities result in a manageable dose rate environment post high yield (20 MJ) shots. The levels of activation generated in air and utilities during D-D and THD shots are small and do not impact work planning post shots.

  5. Comparison of numerical models of a pyrotechnic device

    SciTech Connect (OSTI)

    Pierce, K.G.

    1986-01-01

    The predictions of two numerical models of a hot-wire initiated pyrotechnic device are compared to each other and to experimental results. Both models employ finite difference approximations to the heat diffusion equation in cylindrical coordinates. The temperature dependence of the thermal properties of the pyrotechnic materials and of the bridgewire are modeled. An Arrhenius' model is used to describe the exothermic reaction in the powder. One model employs a single radial coordinate and predicts the radial temperature distribution in the bridgewire and surrounding powder mass. In addition to the radial coordinate, the other model also employs a longitudinal coordinate to predict the temperature distribution parallel to the axis of the bridgewire. The predictions of the two-dimensional model concerning the energy requirements for ignition and the energy losses from the ends of the bridgewire are presented. A comparison of the predictions of the two models and the development of thermal gradients are employed to define the regime where the assumption, in the one-dimensional model, of negligible heat transfer axial to the bridgewire does not lead to significant error. The general problems associated with predicting ignition from a diffusion model are also discussed.

  6. The HD 5980 multiple system: Masses and evolutionary status

    SciTech Connect (OSTI)

    Koenigsberger, Gloria [Instituto de Ciencias Fsicas, Universidad Nacional Autnoma de Mxico, Ave. Universidad S/N, Cuernavaca, Morelos 62210 (Mexico); Morrell, Nidia [Las Campanas Observatory, The Carnegie Observatories, Colina El Pino s/n, Casillas 601, La Serena (Chile); Hillier, D. John [Department of Physics and Astronomy, and Pittsburgh Particle Physics, Astrophysics and Cosmology Center (PITT PACC), 3941 O'Hara Street, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Gamen, Roberto [Facultad de Ciencias Astronmicas y Geofsicas, Universidad Nacional de La Plata, and Instituto de Astrofsica de La Plata (CCT La Plata-CONICET), Paseo del Bosque S/N, B1900FWA La Plata (Argentina); Schneider, Fabian R. N.; Gonzlez-Jimnez, Nicols; Langer, Norbert [Argelander-Institut fr Astronomie, Auf dem Hgel 71, D-53121 Bonn (Germany); Barb, Rodolfo, E-mail: gloria@astro.unam.mx, E-mail: nmorrell@lco.edu, E-mail: hillier@pitt.edu, E-mail: rgamen@fcaglp.unlp.edu.ar, E-mail: fschneid@astro.uni-bonn.de, E-mail: ngonzalez@astro.uni-bonn.de, E-mail: nlanger@astro.uni-bonn.de, E-mail: rbarba@dfuls.cl [Departamento de Fsica, Av. Juan Cisternas 1200 Norte, Universidad de la Serena, La Serena (Chile)

    2014-10-01

    New spectroscopic observations of the LBV/WR multiple system HD 5980 in the Small Magellanic Cloud are used to address the question of the masses and evolutionary status of the two very luminous stars in the 19.3 day eclipsing binary system. Two distinct components of the N V 4944 line are detected in emission and their radial velocity variations are used to derive masses of 61 and 66 M {sub ?}, under the assumption that binary interaction effects on this atomic transition are negligible. We propose that this binary system is the product of quasi-chemically homogeneous evolution with little or no mass transfer. Thus, both of these binary stars may be candidates for gamma-ray burst progenitors or even pair instability supernovae. Analysis of the photospheric absorption lines belonging to the third-light object in the system confirm that it consists of an O-type star in a 96.56 day eccentric orbit (e = 0.82) around an unseen companion. The 5:1 period ratio and high eccentricities of the two binaries suggest that they may constitute a hierarchical quadruple system.

  7. Shell effects in hot nuclei and their influence on nuclear composition in supernova matter

    SciTech Connect (OSTI)

    Nishimura, Suguru [Department of Pure and Applied Physics, Waseda University, 3-4-1 Okubo Shinjuku-ku, Tokyo 169-8555 (Japan); Takano, Masatoshi [Department of Pure and Applied Physics, Waseda University, 3-4-1 Okubo Shinjuku-ku, Tokyo 169-8555, Japan and Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo Shinjuku-ku, Tokyo 169-8555 (Japan)

    2014-05-02

    We calculate nuclear composition in supernova (SN) matter explicitly taking into account the temperature dependence of nuclear shell effects. The abundance of nuclei in SN matter is important in the dynamics of core-collapse supernovae and, in recently constructed equations of state (EOS) for SN matter, the composition of nuclei are calculated assuming nuclear statistical equilibrium wherein the nuclear internal free energies govern the composition. However, in these EOS, thermal effects on the shell energy are not explicitly taken into account. To address this shortfall, we calculate herein the shell energies of hot nuclei and examine their influence on the composition of SN matter. Following a simplified macroscopic-microscopic approach, we first calculate single-particle (SP) energies by using a spherical Woods-Saxon potential. Then we extract shell energies at finite temperatures using Strutinsky method with the Fermi distribution as the average occupation probability of the SP levels. The results show that at relatively low temperatures, shell effects are still important and magic nuclei are abundant. However, at temperatures above approximately 2 MeV, shell effects are almost negligible, and the mass fractions with shell energies including the thermal effect are close to those obtained from a simple liquid drop model at finite temperatures.

  8. Large area graphene ion sensitive field effect transistors with tantalum pentoxide sensing layers for pH measurement at the Nernstian limit

    SciTech Connect (OSTI)

    Fakih, Ibrahim, E-mail: ibrahim.fakih@mail.mcgill.ca; Sabri, Shadi; Szkopek, Thomas, E-mail: thomas.szkopek@mcgill.ca [Department of Electrical and Computer Engineering, McGill University, Montreal, Quebec H3A 2A7 (Canada); Mahvash, Farzaneh [Department of Electrical and Computer Engineering, McGill University, Montreal, Quebec H3A 2A7 (Canada); Dpartement de Chimie et Biochimie, Universite du Qubec Montral, Montreal, Quebec H3C 3P8 (Canada); Nannini, Matthieu [McGill Nanotools Microfab, McGill University, Montreal, Quebec H3A 2A7 (Canada); Siaj, Mohamed [Dpartement de Chimie et Biochimie, Universite du Qubec Montral, Montreal, Quebec H3C 3P8 (Canada)

    2014-08-25

    We have fabricated and characterized large area graphene ion sensitive field effect transistors (ISFETs) with tantalum pentoxide sensing layers and demonstrated pH sensitivities approaching the Nernstian limit. Low temperature atomic layer deposition was used to deposit tantalum pentoxide atop large area graphene ISFETs. The charge neutrality point of graphene, inferred from quantum capacitance or channel conductance, was used to monitor surface potential in the presence of an electrolyte with varying pH. Bare graphene ISFETs exhibit negligible response, while graphene ISFETs with tantalum pentoxide sensing layers show increased sensitivity reaching up to 55?mV/pH over pH 3 through pH 8. Applying the Bergveld model, which accounts for site binding and a Guoy-Chapman-Stern picture of the surface-electrolyte interface, the increased pH sensitivity can be attributed to an increased buffer capacity reaching up to 10{sup 14} sites/cm{sup 2}. ISFET response was found to be stable to better than 0.05 pH units over the course of two weeks.

  9. Pionic contribution to neutrinoless double beta decay

    SciTech Connect (OSTI)

    Vergados, J. D. [Physics Department, University of Ioannina, Ioannina, GR 451 10 (Greece); Theory Division, CERN, Geneva (Switzerland); Faessler, Amand [Institute fuer Theoretische Physik, Universitaet Tuebingen (Germany); Toki, H. [RCNP, Osaka University, Osaka, 567-0047 (Japan)

    2010-02-01

    It is well known that neutrinoless double decay is going to play a crucial role in settling the neutrino properties, which cannot be extracted from the neutrino oscillation data. It is, in particular, expected to settle the absolute scale of neutrino mass and determine whether the neutrinos are Majorana particles, i.e. they coincide with their own antiparticles. In order to extract the average neutrino mass from the data, one must be able to estimate the contribution of all possible high mass intermediate particles. The latter, which occur in practically all extensions of the standard model, can, in principle, be differentiated from the usual mass term, if data from various targets are available. One, however, must first be able to reliably calculate the corresponding nuclear matrix elements. Such calculations are extremely difficult since the effective transition operators are very short ranged. For such operators processes like pionic contributions, which are usually negligible, turn out to be dominant. We study such an effect in a nonrelativistic quark model for the pion and the nucleon.

  10. High dynamic range measurement of spectral responsivity and linearity of a radiation thermometer using a super-continuum laser and LEDs

    SciTech Connect (OSTI)

    Yoo, Y. S.; Lee, D. H.; Park, C. W.; Park, S. N. [Korea Research Institute of Standards and Science 209 Gajeong-Ro, Yuseong-Gu, Daejon 305-340 (Korea, Republic of)] [Korea Research Institute of Standards and Science 209 Gajeong-Ro, Yuseong-Gu, Daejon 305-340 (Korea, Republic of)

    2013-09-11

    To realize the temperature scale above the freezing point of silver according to the definition of ITS-90, the dynamic range of the spectral responsivity is one of the most important factors which limit its uncertainty. When the residual spectral response at both side bands of a spectral band is not negligible, a significant uncertainty can be caused by a low dynamic range of the spectral responsivity measurement. In general, incandescent lamps are used to measure the spectral responsivity and the linearity. The dynamic range of the spectral responsivity measurement is often limited by a trade-off with the desired spectral resolution, which is less than 6 decades. Nonlinearity is another limiting fact of uncertainties of the temperature scale. Tungsten lamps have disadvantage in the nonlinearity measurements in terms of adjustability of radiance level and spectral selectivity. We report spectral responsivity measurements of which the measurable dynamic range is enhanced 50 times after replacing a QTH lamp with a super continuum laser. We also present a spectrally selected linearity measurement over a wide dynamic range using high-brightness light emitting diode arrays to observe a slight saturation of linearity.

  11. Status of LLNL Hot-Recycled-Solid oil shale retort, January 1991--September 30, 1993

    SciTech Connect (OSTI)

    Cena, R.J.

    1993-11-01

    Our objective, together with our CRADA partners, is to demonstrate advanced technology that could lead to an economic and environmentally acceptable commercialization of oil shale. We have investigated the technical and economic barriers facing the introduction of an oil shale industry and we have chosen Hot-Recycled-Solid (HRS) oil shale retorting as the primary advanced technology of interest. We are investigating this approach through fundamental research, operation of a 4 tonne-per-day HRS pilot plant and development of an Oil Shale Process (OSP) mathematical model. The LLNL Hot-Recycled-Solid process has the potential to improve existing oil shale technology. It processes oil shale in minutes instead of hours, reducing plant size. It processes all oil shale, including fines rejected by other processes. It provides controls to optimize product quality for different applications. It co-generates electricity to maximize useful energy output. And, it produces negligible SO{sub 2} and NO{sub x} emissions, a non-hazardous waste shale and uses minimal water.

  12. Status of LLNL Hot-Recycled-Solid oil shale retort

    SciTech Connect (OSTI)

    Baldwin, D.E.; Cena, R.J.

    1993-12-31

    We have investigated the technical and economic barriers facing the introduction of an oil shale industry and we have chosen Hot-Recycled-Solid (HRS) oil shale retorting as the primary advanced technology of interest. We are investigating this approach through fundamental research, operation of a 4 tonne-per-day, HRS pilot plant and development of an Oil Shale Process (OSP) mathematical model. Over the last three years, from June 1991 to June 1993, we completed a series of runs (H10--H27) using the 4-TPD pilot plant to demonstrate the technical feasibility of the HRS process and answer key scale-up questions. With our CRADA partners, we seek to further develop the HRS technology, maintain and enhance the knowledge base gained over the past two decades through research and development by Government and industry and determine the follow on steps needed to advance the technology towards commercialization. The LLNL Hot-Recycled-Solid process has the potential to improve existing oil shale technology. It processes oil shale in minutes instead of hours, reducing plant size. It processes all oil shale, including fines rejected by other processes. It provides controls to optimize product quality for different applications. It co-generates electricity to maximize useful energy output. And, it produces negligible SO{sub 2} and NO{sub x} emissions, a non-hazardous waste shale and uses minimal water.

  13. Quasi-free Cross Section Measurements at CLAS: ? D ? p ? ? ( p ) , ? D ? K ? ( 892 ) 0 ? ( p ) , ? D ? K + ? ? ( 1385 ) ? ( p )

    SciTech Connect (OSTI)

    Mattione, Paul

    2014-09-01

    Preliminary measurements of the quasi-free differential cross sections of the gD -->pp-(p), gD --> K*(892)0L(p), and gD --> K+S*(1385)?(p) reactions are shown using data from the Jefferson Lab Hall B CLAS g13 experiment. No experimental cross section data have yet been published on gD --> K*(892)0L(p), and the only published cross section data on gD --> K+S*(1385)?(p) are at forward angles, where t-channel K+ and K*+ exchanges are predicted to dominate. These data can be used to contribute to the search for the "missing" N* resonances, some of which are predicted to have non-negligible couplings to the excited strangeness channels. These cross sections are shown to be sizable compared to the ground-state channels, indicating that it is important to include excited channels in coupled-channels analyses used to extract the N* resonances. In addition, the gD --> pp?(p) data provide a significant increase to the world statistics, and will be used to study rescattering effects within the deuteron.

  14. Observation of finite-wavelength screening in high-energy-density matter

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chapman, D. A.; Vorberger, J.; Fletcher, L. B.; Baggott, R. A.; Divol, L.; Döppner, T.; Falcone, R. W.; Glenzer, S. H.; Gregori, G.; Guymer, T. M.; et al

    2015-04-23

    A key component for the description of charged particle systems is the screening of the Coulomb interaction between charge carriers. First investigated in the 1920s by Debye and Hückel for electrolytes, charge screening is important for determining the structural and transport properties of matter as diverse as astrophysical and laboratory plasmas, nuclear matter such as quark-gluon plasmas, electrons in solids, planetary cores and charged macromolecules. For systems with negligible dynamics, screening is still mostly described using a Debye–Hückel-type approach. Here, we report the novel observation of a significant departure from the Debye–Hückel-type model in high-energy-density matter by probing laser-driven, shock-compressedmore » plastic with high-energy X-rays. We use spectrally resolved X-ray scattering in a geometry that enables direct investigation of the screening cloud, and demonstrate that the observed elastic scattering amplitude is only well described within a more general approach.« less

  15. Kinetic mix mechanisms in shock-driven inertial confinement fusion implosions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rinderknecht, H. G.; Sio, H.; Li, C. K.; Hoffman, N.; Zylstra, A. B.; Rosenberg, M. J.; Frenje, J. A.; Gatu Johnson, M.; Seguin, F. H.; Petrasso, R. D.; et al

    2014-05-19

    Shock-driven implosions of thin-shell capsules, or ''exploding pushers,'' generate low-density, high-temperature plasmas in which hydrodynamic instability growth is negligible and kinetic effects can play an important role. Data from implosions of thin deuterated-plastic shells with hydroequivalent D3He gas fills ranging from pure deuterium to pure 3He [H. G. Rinderknecht et al., Phys. Rev. Lett. 112, 135001 (2014)] were obtained to evaluate non-hydrodynamic fuel-shell mix mechanisms. Simulations of the experiments including reduced ion kinetic models support ion diffusion as an explanation for these data. Several additional kinetic mechanisms are investigated and compared to the data to determine which are important inmore » the experiments. Shock acceleration of shell deuterons is estimated to introduce mix less than or comparable to the amount required to explain the data. Beam-target mechanisms are found to produce yields at most an order of magnitude less than the observations« less

  16. Evidence for the temperature dependence of phase transformation behavior of silicon at nanoscale

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mangalampalli S. R. N., Kiran; Tran, Tuan; Smillie, Lachlan; Haberl, Bianca; Subianto, D.; Williams, James S.; Bradby, Jodie E.

    2015-01-01

    This study uses the in-situ high-temperature nanoindentation coupled with electrical measurements to investigate the temperature dependence (25 to 200 C) of the phase transformation behavior of crystalline silicon (dc-Si) at the nanoscale. Along with in-situ indentation and electrical data, ex-situ characterizations such as Raman and cross-sectional transmission electron microscopy (XTEM) have been used to reveal the dominant mode of deformation under the indenter. In contrast to the previous studies, the dominant mode of deformation under the nanoindenter at elevated temperatures is not the dc-Si to metallic phase ( -Sn) transformation. Instead, XTEM images from 150 C indents reveal that themore » dominant mode of deformation is twinning along {111} planes. While the in-situ high-temperature electrical measurements show an increase in the current due to metallic phase formation up to 125 C, it is absent 150 C, revealing that the formation of the metallic phase is negligible in this regime. Thus, this work provides clear insight into the temperature dependent deformation mechanisms in dc-Si at the nanoscale.« less

  17. Fatigue Performance of Advanced High-Strength Steels (AHSS) GMAW Joints

    SciTech Connect (OSTI)

    Feng, Zhili; Sang, Yan; Jiang, Cindy; Chiang, Dr. John; Kuo, Dr. Min

    2009-01-01

    The fatigue performance of gas metal arc welding (GMAW) joints of advanced high strength steels (AHSS) are compared and analyzed. The steel studied included a number of different grades of AHSS and baseline mild steels: DP600, DP780, DP980, M130, M220, solution annealed boron steel, fully hardened boron steels, HSLA690 and DR210 (a mild steel). Fatigue testing was conducted under a number of nominal stress ranges to obtain the S/N curves of the weld joints. A two-phase analytical model is developed to predict the fatigue performance of AHSS welds. It was found that there are appreciable differences in the fatigue S/N curves among different AHSS joints made using the same welding practices, suggesting that the local microstructure in the weld toe and root region plays non-negligible role in the fatigue performance of AHSS welds. Changes in weld parameters can influence the joint characteristics which in turn influence fatigue life of the weld joints, particularly of those of higher strength AHSS. The analytical model is capable of reasonably predicting the fatigue performance of welds made with various steel grades in this study.

  18. Effect of short-term material balances on the projected uranium measurement uncertainties for the gas centrifuge enrichment plant

    SciTech Connect (OSTI)

    Younkin, J.M.; Rushton, J.E.

    1980-02-05

    A program is under way to design an effective International Atomic Energy Agency (IAEA) safeguards system that could be applied to the Portsmouth Gas Centrifuge Enrichment Plant (GCEP). This system would integrate nuclear material accountability with containment and surveillance. Uncertainties in material balances due to errors in the measurements of the declared uranium streams have been projected on a yearly basis for GCEP under such a system in a previous study. Because of the large uranium flows, the projected balance uncertainties were, in some cases, greater than the IAEA goal quantity of 75 kg of U-235 contained in low-enriched uranium. Therefore, it was decided to investigate the benefits of material balance periods of less than a year in order to improve the sensitivity and timeliness of the nuclear material accountability system. An analysis has been made of projected uranium measurement uncertainties for various short-term material balance periods. To simplify this analysis, only a material balance around the process area is considered and only the major UF/sub 6/ stream measurements are included. That is, storage areas are not considered and uranium waste streams are ignored. It is also assumed that variations in the cascade inventory are negligible compared to other terms in the balance so that the results obtained in this study are independent of the absolute cascade inventory. This study is intended to provide information that will serve as the basis for the future design of a dynamic materials accounting component of the IAEA safeguards system for GCEP.

  19. Improved Characterization of Transmitted Wavefront Error on CADB Epoxy-Free Bonded Solid State Laser Materials

    SciTech Connect (OSTI)

    Bayramian, A

    2010-12-09

    Current state-of-the-art and next generation laser systems - such as those used in the NIF and LIFE experiments at LLNL - depend on ever larger optical elements. The need for wide aperture optics that are tolerant of high power has placed many demands on material growers for such diverse materials as crystalline sapphire, quartz, and laser host materials. For such materials, it is either prohibitively expensive or even physically impossible to fabricate monolithic pieces with the required size. In these cases, it is preferable to optically bond two or more elements together with a technique such as Chemically Activated Direct Bonding (CADB{copyright}). CADB is an epoxy-free bonding method that produces bulk-strength bonded samples with negligible optical loss and excellent environmental robustness. The authors have demonstrated CADB for a variety of different laser glasses and crystals. For this project, they will bond quartz samples together to determine the suitability of the resulting assemblies for large aperture high power laser optics. The assemblies will be evaluated in terms of their transmitted wavefront error, and other optical properties.

  20. A NEW INTERPHASE FORCE IN TWO-PHASE FLUIDIZED BEDS

    SciTech Connect (OSTI)

    D. ZHANG; W. VANDERHEYDEN

    2001-05-01

    Mesoscale structures such as particle clusters have been observed both in experiments and in numerical simulations of circulating fluidized beds. In a numerical simulation, in order to account for the effects of such mesoscale structures, the computational grids have to be fine enough. The use of such fine grids is impractical in engineering applications due to excessive computational costs. To predict the macroscopic behavior of a fluidized bed with reasonable computation cost, they perform a second average over the averaged equations for two-phase flows. A mesoscale inter-phase exchange force is found to be the correlation of the particle volume fraction and the pressure gradient. This force is related to the mesoscale added mass of the two-phase flow. Typically, added mass for particle scale interactions is negligible in gas-solid flows since the gas density is small compared to density of solid particles. However, for a mesoscale structure, such as a bubble, the surrounding media is the mixture of gas and particles. The surrounding fluid density experienced by the mesoscale structure is the density of the surrounding mixture. Therefore, the added mass of a mesoscale structure, such as bubbles, cannot be neglected. The property of this new force is studied based on the numerical simulation of a fluidized bed using high grid resolution. It is shown that this force is important in the region where the particle volume fraction is high. The effects of the inhomogeneity to the interphase drag are also studied.

  1. Inflatable Dark Matter

    SciTech Connect (OSTI)

    Davoudiasl, Hooman; Hooper, Dan; McDermott, Samuel D.

    2015-07-30

    We describe a general scenario, dubbed Inflatable Dark Matter, in which the density of dark matter particles can be reduced through a short period of late-time inflation in the early universe. The overproduction of dark matter that is predicted within many otherwise well-motivated models of new physics can be elegantly remedied within this context, without the need to tune underlying parameters or to appeal to anthropic considerations. Thermal relics that would otherwise be disfavored can easily be accommodated within this class of scenarios, including dark matter candidates that are very heavy or very light. Furthermore, the non-thermal abundance of GUT or Planck scale axions can be brought to acceptable levels, without invoking anthropic tuning of initial conditions. Additionally, a period of late-time inflation could have occurred over a wide range of scales from ~ MeV to the weak scale or above, and could have been triggered by physics within a hidden sector, with small but not necessarily negligible couplings to the Standard Model.

  2. Results of Second Outdoor Comparison Between Absolute Cavity Pyrgeometer (ACP) and Infrared Integrating Sphere (IRIS) Radiometer at PMOD (Presentation)

    SciTech Connect (OSTI)

    Reda, I.; Grobner, J.; Wacker, S.

    2014-01-01

    The Absolute Cavity Pyrgeometer (ACP) and InfraRed Integrating Sphere radiometer (IRIS) are developed to establish a world reference for calibrating pyrgeometers with traceability to SI units. The two radiometers are un-windowed with negligible spectral dependence, and traceable to SI units through the temperature scale (ITS-90). The second outdoor comparison between the two designs was held from September 30 to October 11, 2013 at the Physikalisch-Metorologisches Observatorium Davos (PMOD). The difference between the irradiance measured by ACP and that of the IRIS was within 1 W/m2 (3 IRISs: PMOD + Australia + Germany). From the first and second comparisons, a difference of 4-6 W/m2 was observed between the irradiance measured by ACP&IRIS and that of the interim World Infrared Standard Group (WISG). This presentation includes results from the first and second comparison in an effort to establish the world reference for pyrgeometer calibrations, a key deliverable for the World Meteorological Organization (WMO), and the DOE-ASR.

  3. Measurement of SQUID noise levels for SuperCDMS SNOLAB detectors - Final Paper

    SciTech Connect (OSTI)

    Lee, Maxwell

    2015-08-27

    SuperCDMS SNOLAB is a second generation direct dark matter search. In the SuperCDMS SNOLAB experiment, detectors are able to pick up from signals from dark matter nuclear recoil interactions which occur inside the bulk of the detectors. These interactions produce both phonon and charge signals. HEMTs read out charge signals whereas TES are used to detect phonon signals which are then read out by SQUID amplifiers. SQUID amplifiers must add negligible noise to the TES intrinsic noise which has been previously measured and is approximately 50pA/?Hz down to 100Hz for ease of signal distinguishability in dark matter nuclear interactions. The intrinsic noise level of the SQUID was tested in the SLAC 300mK fridge and determined to provide adequately low levels of noise with a floor of approximately 3pA/?Hz. Furthermore, a 10x amplifier was tested for addition of extraneous noise. This noise was investigated with and without this amplifier, and it was found that it did not add a significant amount of noise to the intrinsic SQUID noise.

  4. The Effect Of ZnO Addition On Co/C Catalyst For Vapor And Aqueous Phase Reforming Of Ethanol

    SciTech Connect (OSTI)

    Davidson, Stephen; Sun, Junming; Hong, Yongchun; Karim, Ayman M.; Datye, Abhaya K.; Wang, Yong

    2014-02-05

    The effect of ZnO addition on the oxidation behavior of Co along with catalytic performance in vapor and aqueous phase reforming of ethanol were investigated on Co supported on carbon black (XC-72R). Carbon was selected to minimize the support interactions. Effect of ZnO addition during both vapor and aqueous phase reforming were compared at 250 C. ZnO addition inhibited the reduction of cobalt oxides by H2 and created surface sites for H2O activation. During vapor phase reforming at 450 C the redox of cobalt, driven by steam oxidation and H2 reduction, trended to an equilibrium of Co0/Co2+. ZnO showed no significant effect on cobalt oxidation, inferred from the minor changes of C1 product yield. Surface sites created by ZnO addition enhanced water activation and oxidation of surface carbon species, increasing CO2 selectivity. At 250 C cobalt reduction was minimal, in situ XANES demonstrated that ZnO addition significantly facilitated oxidation of Co0 under vapor phase reforming conditions, demonstrated by lower C1 product yield. Sites introduced by ZnO addition improved the COx selectivity at 250 C. Both Co/C and Co-ZnO/C rapidly oxidized under aqueous phase reaction conditions at 250 C, showing negligible activity in aqueous phase reforming. This work suggests that ZnO affects the activation of H2O for Co catalysts in ethanol reforming.

  5. The role of acetate in alcohol-induced alterations of uterine glucose metabolism in the mouse during pregnancy

    SciTech Connect (OSTI)

    Simm, B. ); Murdoch, R.N. )

    1990-01-01

    The acute exposure of mice to ethanol during post-implantation pregnancy has been reported to cause alterations in the levels of several glycolytic intermediates in the uterus, suggesting a possible indirect mechanism of alcohol embryo-toxicity. The present study was undertaken to assess whether the ethanol metabolite, acetate is implicated in this phenomenon. Blood and uterine alcohol concentrations in day 9 - pregnant Quackenbush Swiss mice were maximal 15 minutes after the intraperitoneal injection of ethanol, and fell to almost negligible levels 6 hours later. In response to this treatment, the levels of blood and uterine acetate increased, liver glycogen decreased, plasma glucose increased, and uterine glucose, glucose-6-phosphate (G-6-P), fructose-6-phosphate (F-6-P), and citrate increased. When acetate was administered to pregnant mice in amounts approximating those generated by exposure to alcohol, the levels of uterine F-6-P and citrate increased while other metabolic parameters remained unaffected. The administration of 4-methylpyrazole to mice subsequently treated with alcohol produced conditions of alcohol exposure in the absence of ethanol-derived acetate and depressed the ethanol-induced rise in uterine G-6-P and citrate.

  6. Nanolaminated Permalloy Core for High-Flux, High-Frequency Ultracompact Power Conversion

    SciTech Connect (OSTI)

    Kim, J; Kim, M; Galle, P; Herrault, F; Shafer, R; Park, JY; Allen, MG

    2013-09-01

    Metallic magnetic materials have desirable magnetic properties, including high permeability, and high saturation flux density, when compared with their ferrite counterparts. However, eddy-current losses preclude their use in many switching converter applications, due to the challenge of simultaneously achieving sufficiently thin laminations such that eddy currents are suppressed (e.g., 500 nm-1 mu m for megahertz frequencies), while simultaneously achieving overall core thicknesses such that substantial power can be handled. A CMOS-compatible fabrication process based on robot-assisted sequential electrodeposition followed by selective chemical etching has been developed for the realization of a core of substantial overall thickness (tens to hundreds of micrometers) comprised of multiple, stacked permalloy (Ni80Fe20) nanolaminations. Tests of toroidal inductors with nanolaminated cores showed negligible eddy-current loss relative to total core loss even at a peak flux density of 0.5 T in the megahertz frequency range. To illustrate the use of these cores, a buck power converter topology is implemented with switching frequencies of 1-2 MHz. Power conversion efficiency greater than 85% with peak operating flux density of 0.3-0.5 T in the core and converter output power level exceeding 5 W was achieved.

  7. hhjj production at the LHC

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dolan, Matthew J.; Englert, Christoph; Greiner, Nicolas; Nordstrom, Karl; Spannowsky, Michael

    2015-08-25

    The search for di-Higgs production at the LHC in order to set limits on the Higgs trilinear coupling and constraints on new physics is one of the main motivations for the LHC high-luminosity phase. Recent experimental analyses suggest that such analyses will only be successful if information from a range of channels is included. We therefore investigate di-Higgs production in association with two hadronic jets and give a detailed discussion of both the gluon- and the weak boson-fusion (WBF) contributions, with a particular emphasis on the phenomenology with modified Higgs trilinear and quartic gauge couplings. We perform a detailed investigationmore » of the full hadronic final state and find that hhjj production should add sensitivity to a di-Higgs search combination at the HL-LHC with 3 ab-1. Since the WBF and GF contributions are sensitive to different sources of physics beyond the Standard Model, we devise search strategies to disentangle and isolate these production modes. In addition, while gluon fusion remains non-negligible in WBF-type selections, sizeable new physics contributions to the latter can still be constrained. As an example of the latter point we investigate the sensitivity that can be obtained for a measurement of the quartic Higgs–gauge boson couplings.« less

  8. Electrochemical-thermal modeling and microscale phase change for passive internal thermal management of lithium ion batteries.

    SciTech Connect (OSTI)

    Fuller, Thomas F.; Bandhauer, Todd; Garimella, Srinivas

    2012-01-01

    A fully coupled electrochemical and thermal model for lithium-ion batteries is developed to investigate the impact of different thermal management strategies on battery performance. In contrast to previous modeling efforts focused either exclusively on particle electrochemistry on the one hand or overall vehicle simulations on the other, the present work predicts local electrochemical reaction rates using temperature-dependent data on commercially available batteries designed for high rates (C/LiFePO{sub 4}) in a computationally efficient manner. Simulation results show that conventional external cooling systems for these batteries, which have a low composite thermal conductivity ({approx}1 W/m-K), cause either large temperature rises or internal temperature gradients. Thus, a novel, passive internal cooling system that uses heat removal through liquid-vapor phase change is developed. Although there have been prior investigations of phase change at the microscales, fluid flow at the conditions expected here is not well understood. A first-principles based cooling system performance model is developed and validated experimentally, and is integrated into the coupled electrochemical-thermal model for assessment of performance improvement relative to conventional thermal management strategies. The proposed cooling system passively removes heat almost isothermally with negligible thermal resistances between the heat source and cooling fluid. Thus, the minimization of peak temperatures and gradients within batteries allow increased power and energy densities unencumbered by thermal limitations.

  9. Xe-135 Production from Cf-252

    SciTech Connect (OSTI)

    C. A. McGrath; T. P. Houghton; J. K. Pfeiffer; R. K. Hague

    2012-03-01

    135Xe is a good indicator that fission has occurred and is a valuable isotope that helps enforce the Comprehensive Test Ban Treaty. Due to its rather short half life and minimal commercial interest, there are no known sources where 135Xe can be purchased. Readily available standards of this isotope for calibrating collection and analytical techniques would be very useful. 135Xe can be produced in the fissioning of actinide isotopes, or by neutron capture on 134Xe. Since the neutron capture cross section of 134Xe is 3 mB, neutron capture is a low yield, though potentially useful, production route. 135Xe is also produced by spontaneous fission of 252Cf. 252Cf has a spontaneous fission rate of about 6 x 1011 s-1g-1. The cumulative yield from the spontaneous fission of 252Cf is 4.19%; and the competing neutron capture reaction that depletes 135Xe in thermal reactor systems is negligible because the neutron capture cross-section is low for fast fission neutrons. At the INL, scientists have previously transported fission products from an electroplated 252Cf thin source for the measurement of nuclear data of short-lived fission products using a technique called He-Jet collection. We have applied a similar system to the collection of gaseous 135Xe, in order to produce valuable standards of this isotope.

  10. Heavy-quark production in ultrarelativistic heavy-ion collisions within a partonic transport model

    SciTech Connect (OSTI)

    Uphoff, Jan; Fochler, Oliver; Greiner, Carsten; Xu Zhe

    2010-10-15

    The production and space-time evolution of charm and bottom quarks in nucleus-nucleus collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) are investigated with the partonic transport model BAMPS (Boltzmann approach of multiparton scatterings). Heavy quarks, produced in primary hard parton scatterings during nucleon-nucleon collisions, are sampled using the Monte Carlo event generator pythia or the leading-order minijet model in conjunction with the Glauber model, revealing a strong sensitivity on the parton distribution functions, scales, and heavy-quark mass. In a comprehensive study exploring different charm masses, K factors, and possible initial gluon conditions, secondary production and the evolution of heavy quarks are examined within a fully dynamic BAMPS simulation for central heavy-ion collisions at RHIC and LHC. Although charm production in the quark-gluon plasma can be neglected at RHIC, it is significant at LHC but very sensitive to the initial conditions and the charm mass. Bottom production in the quark-gluon plasma, however, is negligible both at RHIC and LHC.

  11. Radiography apparatus using gamma rays emitted by water activated by fusion neutrons

    DOE Patents [OSTI]

    Smith, D.L.; Ikeda, Yujiro; Uno, Yoshitomo

    1996-11-05

    Radiography apparatus includes an arrangement for circulating pure water continuously between a location adjacent a source of energetic neutrons, such as a tritium target irradiated by a deuteron beam, and a remote location where radiographic analysis is conducted. Oxygen in the pure water is activated via the {sup 16}O(n,p){sup 16}N reaction using {sup 14}N-MeV neutrons produced at the neutron source via the {sup 3}H(d,n){sup 4}He reaction. Essentially monoenergetic gamma rays at 6.129 (predominantly) and 7.115 MeV are produced by the 7.13-second {sup 16}N decay for use in radiographic analysis. The gamma rays have substantial penetrating power and are useful in determining the thickness of materials and elemental compositions, particularly for metals and high-atomic number materials. The characteristic decay half life of 7.13 seconds of the activated oxygen is sufficient to permit gamma ray generation at a remote location where the activated water is transported, while not presenting a chemical or radioactivity hazard because the radioactivity falls to negligible levels after 1--2 minutes. 15 figs.

  12. Radiography apparatus using gamma rays emitted by water activated by fusion neutrons

    DOE Patents [OSTI]

    Smith, Donald L.; Ikeda, Yujiro; Uno, Yoshitomo

    1996-01-01

    Radiography apparatus includes an arrangement for circulating pure water continuously between a location adjacent a source of energetic neutrons, such as a tritium target irradiated by a deuteron beam, and a remote location where radiographic analysis is conducted. Oxygen in the pure water is activated via the .sup.16 O(n,p).sup.16 N reaction using .sup.14 -MeV neutrons produced at the neutron source via the .sup.3 H(d,n).sup.4 He reaction. Essentially monoenergetic gamma rays at 6.129 (predominantly) and 7.115 MeV are produced by the 7.13-second .sup.16 N decay for use in radiographic analysis. The gamma rays have substantial penetrating power and are useful in determining the thickness of materials and elemental compositions, particularly for metals and high-atomic number materials. The characteristic decay half life of 7.13 seconds of the activated oxygen is sufficient to permit gamma ray generation at a remote location where the activated water is transported, while not presenting a chemical or radioactivity hazard because the radioactivity falls to negligible levels after 1-2 minutes.

  13. A high sensitivity fiber optic macro-bend based gas flow rate transducer for low flow rates: Theory, working principle, and static calibration

    SciTech Connect (OSTI)

    Schena, Emiliano; Saccomandi, Paola; Silvestri, Sergio

    2013-02-15

    A novel fiber optic macro-bend based gas flowmeter for low flow rates is presented. Theoretical analysis of the sensor working principle, design, and static calibration were performed. The measuring system consists of: an optical fiber, a light emitting diode (LED), a Quadrant position sensitive Detector (QD), and an analog electronic circuit for signal processing. The fiber tip undergoes a deflection in the flow, acting like a cantilever. The consequent displacement of light spot center is monitored by the QD generating four unbalanced photocurrents which are function of fiber tip position. The analog electronic circuit processes the photocurrents providing voltage signal proportional to light spot position. A circular target was placed on the fiber in order to increase the sensing surface. Sensor, tested in the measurement range up to 10 l min{sup -1}, shows a discrimination threshold of 2 l min{sup -1}, extremely low fluid dynamic resistance (0.17 Pa min l{sup -1}), and high sensitivity, also at low flow rates (i.e., 33 mV min l{sup -1} up to 4 l min{sup -1} and 98 mV min l{sup -1} from 4 l min{sup -1} up to 10 l min{sup -1}). Experimental results agree with the theoretical predictions. The high sensitivity, along with the reduced dimension and negligible pressure drop, makes the proposed transducer suitable for medical applications in neonatal ventilation.

  14. Rotational and radial velocities of 1.3-2.2 M {sub ?} red giants in open clusters

    SciTech Connect (OSTI)

    Carlberg, Joleen K.

    2014-06-01

    This study presents the rotational distribution of red giant (RG) stars in 11 old to intermediate age open clusters. The masses of these stars are all above the Kraft break, so they lose negligible amounts of their birth angular momentum (AM) during the main-sequence (MS) evolution. However, they do span a mass range with quite different AM distributions imparted during formation, with the stars less massive than ?1.6M {sub ?} arriving on the MS with lower rotation rates than the more massive stars. The majority of RGs in this study are slow rotators across the entire red giant branch regardless of mass, supporting the picture that intermediate-mass stars rapidly spin down when they evolve off the MS and develop convection zones capable of driving a magnetic dynamo. Nevertheless, a small fraction of RGs in open clusters show some level of enhanced rotation, and faster rotators are as common in these clusters as in the field RG population. Most of these enhanced rotators appear to be red clump stars, which is also true of the underlying stellar sample, while others are clearly RGs that are above or below the clump. In addition to rotational velocities, the radial velocities (RVs) and membership probabilities of individual stars are also presented. Cluster heliocentric RVs for NGC 6005 and Pismis 18 are reported for the first time.

  15. Low-lying dipole response in the stable {sup 40,48}Ca nuclei with the second random-phase approximation

    SciTech Connect (OSTI)

    Gambacurta, D.; Catara, F.

    2011-09-15

    Low-energy dipole excitations are analyzed for the stable isotopes {sup 40}Ca and {sup 48}Ca in the framework of the Skyrme-second random-phase approximation. The corresponding random-phase approximation calculations provide a negligible strength distribution for both nuclei in the energy region from 5 to 10 MeV. The inclusion and the coupling of 2 particle-2 hole configurations in the second random-phase approximation lead to an appreciable dipole response at low energies for the neutron-rich nucleus {sup 48}Ca. The presence of a neutron skin in the nucleus {sup 48}Ca would suggest the interpretation of the low-lying response in terms of a pygmy excitation. The composition of the excitation modes (content of 1 particle-1 hole and 2 particle-2 hole configurations), their transition densities and their collectivity (number and coherence of the different contributions) are analyzed. This analysis indicates that, in general, these excitations cannot be clearly interpreted in terms of oscillations of the neutron skin against the core with the exception of the peak with the largest B(E1) value, which is located at 9.09 MeV. For this peak the neutron transition density dominates and the neutron and proton transition densities oscillate out of phase in the internal part of the nucleus leading to a strong mixing of isoscalar and isovector components. Therefore, this state shows some features usually associated to pygmy resonances.

  16. Self-organisation Processes In The Carbon ARC For Nanosynthis

    SciTech Connect (OSTI)

    Ng, J.; Raitses, Yefgeny

    2014-02-02

    The atmospheric pressure carbon arc in inert gases such as helium is an important method for the production of nanomaterials. It has recently been shown that the formation of the carbon deposit on the cathode from gaseous carbon plays a crucial role in the operation of the arc, reaching the high temperatures necessary for thermionic emission to take place even with low melting point cathodes. Based on observed ablation and deposition rates, we explore the implications of deposit formation on the energy balance at the cathode surface, and show how the operation of the arc is self-organised process. Our results suggest that the can arc operate in two di erent regimes, one of which has an important contribution from latent heat to the cathode energy balance. This regime is characterised by the enhanced ablation rate, which may be favourable for high yield synthesis of nanomaterials. The second regime has a small and approximately constant ablation rate with a negligible contribution from latent heat.

  17. Self-organisation Processes In The Carbon ARC For Nanosynthis

    SciTech Connect (OSTI)

    Ng, Jonathan; Raitses, Yevgeny

    2014-02-26

    The atmospheric pressure carbon arc in inert gases such as helium is an important method for the production of nanomaterials. It has recently been shown that the formation of the carbon deposit on the cathode from gaseous carbon plays a crucial role in the operation of the arc, reaching the high temperatures necessary for thermionic emission to take place even with low melting point cathodes. Based on observed ablation and deposition rates, we explore the implications of deposit formation on the energy balance at the cathode surface, and show how the operation of the arc is self-organised process. Our results suggest that the can arc operate in two di erent regimes, one of which has an important contribution from latent heat to the cathode energy balance. This regime is characterised by the enhanced ablation rate, which may be favourable for high yield synthesis of nanomaterials. The second regime has a small and approximately constant ablation rate with a negligible contribution from latent heat.

  18. Laser-launched flyer plate and confined laser ablation for shock wave loading: Validation and applications

    SciTech Connect (OSTI)

    Paisley, Dennis L.; Luo Shengnian; Greenfield, Scott R.; Koskelo, Aaron C.

    2008-02-15

    We present validation and some applications of two laser-driven shock wave loading techniques: laser-launched flyer plate and confined laser ablation. We characterize the flyer plate during flight and the dynamically loaded target with temporally and spatially resolved diagnostics. With transient imaging displacement interferometry, we demonstrate that the planarity (bow and tilt) of the loading induced by a spatially shaped laser pulse is within 2-7 mrad (with an average of 4{+-}1 mrad), similar to that in conventional techniques including gas gun loading. Plasma heating of target is negligible, in particular, when a plasma shield is adopted. For flyer plate loading, supported shock waves can be achieved. Temporal shaping of the drive pulse in confined laser ablation allows for flexible loading, e.g., quasi-isentropic, Taylor-wave, and off-Hugoniot loading. These techniques can be utilized to investigate such dynamic responses of materials as Hugoniot elastic limit, plasticity, spall, shock roughness, equation of state, phase transition, and metallurgical characteristics of shock-recovered samples.

  19. Effects of Laser Energy and Wavelength on the Analysis of LiFePO4 Using Laser Assisted Atom Probe Tomography

    SciTech Connect (OSTI)

    Santhanagopalan, Dhamodaran; Schreiber, Daniel K.; Perea, Daniel E.; Martens, Rich; Janssen, Yuri; Kalifah, Peter; Meng, Ying S.

    2015-01-21

    The effects of laser wavelength (355 nm and 532 nm) and laser pulse energy on the quantitative accuracy of atom probe tomography (APT) examinations of LiFePO4 (LFP) are considered. A systematic investigation of ultraviolet (UV, 355 nm) and green (532 nm) laser assisted APT of LFP has revealed distinctly different behaviors. With the use of UV laser the major issue was identified as the preferential loss of oxygen (up to 10 at. %) while other elements (Li, Fe and P) were observed to be close to nominal ratios. Lowering the laser energy per pulse to 1 pJ increased the observed oxygen concentration to near its correct stoichiometry and was well correlated with systematically higher concentrations of 16O2+ ions. This observation supports the premise that lower laser energies lead to a higher probability of oxygen molecule ionization. Conversely, at higher laser energies the resultant lower effective electric field reduces the probability of oxygen molecule ionization. Green laser assisted field evaporation led to the selective loss of Li (~50% deficiency) and correct ratios of the remaining elements, including the oxygen concentration. The loss of Li is explained by selective dc evaporation of lithium between laser pulses and relatively negligible oxygen loss as neutrals during green-laser pulsing. Lastly, plotting of multihit events on a Saxey plot for the straight-flight path data (green laser only) revealed a surprising dynamic recombination process for some molecular ions mid-flight.

  20. Electron microscope phase enhancement

    DOE Patents [OSTI]

    Jin, Jian; Glaeser, Robert M.

    2010-06-15

    A microfabricated electron phase shift element is used for modifying the phase characteristics of an electron beam passing though its center aperture, while not affecting the more divergent portion of an incident beam to selectively provide a ninety-degree phase shift to the unscattered beam in the back focal plan of the objective lens, in order to realize Zernike-type, in-focus phase contrast in an electron microscope. One application of the element is to increase the contrast of an electron microscope for viewing weakly scattering samples while in focus. Typical weakly scattering samples include biological samples such as macromolecules, or perhaps cells. Preliminary experimental images demonstrate that these devices do apply a ninety degree phase shift as expected. Electrostatic calculations have been used to determine that fringing fields in the region of the scattered electron beams will cause a negligible phase shift as long as the ratio of electrode length to the transverse feature-size aperture is about 5:1. Calculations are underway to determine the feasibility of aspect smaller aspect ratios of about 3:1 and about 2:1.

  1. Validating the role of AFVs in voluntary mobile source emission reduction programs.

    SciTech Connect (OSTI)

    Santini, D. J.; Saricks, C. L.

    1999-03-17

    Late in 1997, EPA announced new allowances for voluntary emission control programs. As a result, the US Department of Energy's (DOE) Clean Cities and other metro areas that have made an ongoing commitment to increasing participation by alternative fuel vehicles (AFVs) in local fleets have the opportunity to estimate the magnitude and obtain emission reduction credit for following through on that commitment. Unexpectedly large reductions in key ozone precursor emissions in key locations and times of the day can be achieved per vehicle-mile by selecting specific light duty AFV offerings from original equipment manufacturers (OEMs) in lieu of their gasoline-fueled counterparts. Additional benefit accrues from the fact that evaporative emissions of non-methane hydrocarbons (generated in the case of CNG, LNG, and LPG by closed fuel-system AFV technology) can be essentially negligible. Upstream emissions from fuel storage and distribution with the airshed of interest are also reduced. This paper provides a justification and outlines a method for including AFVs in the mix of strategies to achieve local and regional improvements in ozone air quality, and for quantifying emission reduction credits. At the time of submission of this paper, the method was still under review by the US EPA Office of Mobile Sources, pending mutually satisfactory resolution of several of its key points. Some of these issues are discussed in the paper.

  2. Extending Higgs inflation with TeV scale new physics

    SciTech Connect (OSTI)

    He, Hong-Jian; Xianyu, Zhong-Zhi

    2014-10-10

    Higgs inflation is among the most economical and predictive inflation models, although the original Higgs inflation requires tuning the Higgs or top mass away from its current experimental value by more than 2σ deviations, and generally gives a negligible tensor-to-scalar ratio r∼10{sup −3} (if away from the vicinity of critical point). In this work, we construct a minimal extension of Higgs inflation, by adding only two new weak-singlet particles at TeV scale, a vector-quark T and a real scalar S . The presence of singlets (T, S) significantly impact the renormalization group running of the Higgs boson self-coupling. With this, our model provides a wider range of the tensor-to-scalar ratio r=O(0.1)−O(10{sup −3}) , consistent with the favored r values by either BICEP2 or Planck data, while keeping the successful prediction of the spectral index n{sub s}≃0.96 . It allows the Higgs and top masses to fully fit the collider measurements. We also discuss implications for searching the predicted TeV-scale vector-quark T and scalar S at the LHC and future high energy pp colliders.

  3. Commercialization of High-Temperature Solar Selective Coating: Cooperative Research and Development Final Report, CRADA Number CRD-08-300

    SciTech Connect (OSTI)

    Gray, M. H.

    2014-01-01

    The goal for Concentrating Solar Power (CSP) technologies is to produce electricity at 15 cents/kilowatt-hour (kWh) with six hours of thermal storage in 2015 (intermediate power) and close to 10 cents/kWh with 12-17 hours of thermal storage in 2020 (baseload power). Cost reductions of up to 50% to the solar concentrator are targeted through technology advances. The overall solar-to-electric efficiency of parabolic-trough solar power plants can be improved and the cost of solar electricity can be reduced by improving the properties of the selective coating on the receiver and increasing the solar-field operating temperature to >450 degrees C. New, more-efficient selective coatings will be needed that have both high solar absorptance and low thermal emittance at elevated temperatures. Conduction and convection losses from the hot absorber surface are usually negligible for parabolic trough receivers. The objective is to develop new, more-efficient selective coatings with both high solar absorptance (..alpha.. > 0.95) and low thermal emittance (..epsilon.. < 0.08 @ 450 degrees C) that are thermally stable above 450 degrees C, ideally in air, with improved durability and manufacturability, and reduced cost.

  4. A reevaluation of the National Emission Standards for Hazardous Air Pollutants (NESHAP - 40 CFR 61, Subpart H) program at Sandia National Laboratories, New Mexico

    SciTech Connect (OSTI)

    Culp, T.A.; Hylko, J.M.

    1997-10-01

    The initial National Emission Standards for Hazardous Air Pollutants (NESHAP - 40 CFR 61, Subpart H) Program at Sandia National Laboratories, New Mexico (SNL/NM) required: (1) continuous air monitoring of sources if the calculated effective dose equivalent (EDE) to the maximum exposed individual (MEI) was > 0.1 mrem/yr; (2) the determination of emissions based on measurements or measured parameters if the EDE to the MEI was < 0.1 mrem/yr; and (3) the calculation of worst case releases when the expected air concentrations were below detection limits using standard monitoring equipment. This conservative interpretation of the regulation guided SNL/NM to model, track, and trend virtually all emission sources with the potential to include any radionuclides. The level of effort required to implement these activities was independent of the EDE contributing from individual sources. A recent programmatic review found the NESHAP program to be in excess of the legal requirements. A further review found that, in summation, 13 of 16 radionuclide sources had a negligible impact on the final calculated EDE to the MEI used to demonstrate compliance at 20 separate on-site receptor locations. A reevaluation was performed to meet the legal requirements of 40 CFR 61, Subpart H, and still be reasonable and appropriate under the existing circumstances.

  5. Settling of loose-fill insulations due to vibration

    SciTech Connect (OSTI)

    Yarbrough, D.W.; McElroy, D.L.; Wright, J.W.

    1981-12-01

    Vibration and impact testing of loose-fill cellulosic, fiberglass, and rock wool insulations has been carried out to provide a data base for settled density tests. The ratio of final density to initial density for the three materials has been determined for repeated 19-mm (0.75-in.) drops, repeated 152-mm (6.0-in.) drops, and vibrations at frequencies from 10 to 60 Hz with displacements from 0.1 mm (0.004 in.) to 6.35 mm (0.25 in.). Repeated 19-mm or 152-mm drops increased the density ratio for rock wool insulation specimens the most, while the cellulosic insulation specimens were affected the least. Density ratios after 200 19-mm drops averaged 1.75 for loose-fill rock wool, 1.45 for loose-fill fiberglass, and 1.27 for loose-fill cellulosic insulations. Vibration tests for 7200 s at 0.1-mm displacement and 15 Hertz produced negligible changes in the densities of all three loose-fill insulations. An 1800-s vibration test at 2.5 mm (0.1 in.) and 10 Hz resulted in average density ratios of 1.05, 1.11, and 1.18 for specimens of loose-fill cellulosic, rock wool, and fiberglass insulations, respectively. Changes in either frequency of vibration, displacement, or test duration can be used to achieve a wide range of laboratory results. Efforts to correlate laboratory results with in situ density measurements are presented.

  6. Settling of loose-fill insulations due to vibration

    SciTech Connect (OSTI)

    Yarbrough, D.W.; Wright, J.H.; McElroy, D.L.; Scanlan, T.F.

    1983-01-01

    Vibration and impact testing of loose-fill cellulosic, fiberglass, and rock wool insulations has been carried out to provide a data base for settled density tests. The ratio of final density to initial density for the three materials has been determined for repeated 19-mm (0.75-in.) drops, repeated 152-mm (6.0-in.) drops, and vibrations at frequencies from 10 to 60 Hz with displacements from 0.1 mm (0.004 in.) to 6.35 mm (0.25 in.). Repeated 19-mm or 152-mm drops increased the density ratio for rock wool insulation specimens the most, while the cellulosic insulation specimens were affected the least. Density ratios after 200 19-mm drops averaged 1.75 for loose-fill rock wool, 1.45 for loose-fill fiberglass, and 1.27 for loose-fill cellulosic insulations. Vibration tests for 7200 s at 0.1-mm displacement and 15 Hertz produced negligible changes in the densities of all three loose-fill insulations. An 1800-s vibration test at 2.5 mm (0.1 in.) and 10 Hz resulted in average density ratios of 1.05, 1.11, and 1.18 for specimens of loose-fill cellulosic, rock wool, and fiberglass insulations, respectively. Changes in either frequency of vibration, displacement, or test duration can be used to achieve a wide range of laboratory results. Efforts to correlate laboratory results with in situ density measurements are presented.

  7. A comparison of hydrogen vs. helium glow discharge effects on fusion device first-wall conditioning

    SciTech Connect (OSTI)

    Dylla, H.F.

    1989-09-01

    Hydrogen- and deuterium-fueled glow discharges are used for the initial conditioning of magnetic fusion device vacuum vessels following evacuation from atmospheric pressure. Hydrogenic glow discharge conditioning (GDC) significantly reduces the near-surface concentration of simple adsorbates, such as H/sub 2/O, CO, and CH/sub 4/, and lowers ion-induced desorption coefficients by typically three orders of magnitude. The time evolution of the residual gas production observed during hydrogen-glow discharge conditioning of the carbon first-wall structure of the TFTR device is similar to the time evolution observed during hydrogen GDC of the initial first-wall configuration in TFTR, which was primarily stainless steel. Recently, helium GDC has been investigated for several wall-conditioning tasks on a number of tokamaks including TFTR. Helium GDC shows negligible impurity removal with stainless steel walls. For impurity conditioning with carbon walls, helium GDC shows significant desorption of H/sub 2/O, CO, and CO/sub 2/; however, the total desorption yield is limited to the monolayer range. In addition, helium GDC can be used to displace hydrogen isotopes from the near-surface region of carbon first-walls in order to lower hydrogenic retention and recycling. 38 refs., 6 figs.

  8. Galvanic corrosion of a copper alloy in lithium bromide heavy brine environments

    SciTech Connect (OSTI)

    Itzhak, D.; Greenberg, T.

    1999-08-01

    Galvanic corrosion of the copper alloy 84% Cu-15% Zn-1% Ni was studied in 55 wt% lithium bromide (LiBr) environments. The galvanic couples studied were: 84% Cu-15% Zn-1% Ni-Ti2, 84% Cu-15% Zn-1% Ni-Ti7, 84% Cu-15% Zn-1% Ni-30% Cu-70% Ni, 84% Cu-15% Zn-1% Ni-Pb, 84% Cu-15% Zn-1% Ni-Ag, and 84% Cu-15% Zn-1% Ni-Sn. Potentiodynamic polarization measurements, open-circuit potential (OCP), and weight change measurements were carried out to evaluate the galvanic effect. Results indicated that Ti alloys and 30% Cu-70% Ni were the most passive alloys tested, and they behaved as cathodes. Although galvanic corrosion was expected, a negligible effect was measured because of an effective passivation layer on the surface of Ti alloys and 30% Cu-70% Ni. Pb, Ag, and Sn showed anodic behavior as compared to 84% Cu-15% Zn-1% Ni. As a result of the galvanic coupling, significant weight loss of these metals was measured. Sn was the most effective anode as compared to the other tested alloys; it acted as a sacrificial anode. Sn provided effective cathodic protection to 84% Cu-15% Zn-1% Ni in 55 wt% LiBr environments at 140 C.

  9. Model for flue-gas desulfurization in a circulating dry scrubber

    SciTech Connect (OSTI)

    Neathery, J.K.

    1996-01-01

    A simple model was developed to describe the absorption of SO{sub 2} in a circulating dry scrubbing (CDS) process, which is a semi dry, lime-based, flue-gas desulfurization (FGD) process that utilizes a circulating fluidized bed arrangement for contacting a sorbent with SO{sub 2}-laden flue gas under coolside conditions. The reaction chemistry is thought to be similar to that of spray-drying absorption. The liquid-phase mass-transfer coefficient was successfully modeled as a function of the sorbent particle spacing on the wetted surfaces. Gas-phase mass-transfer resistances were assumed to be insignificant. Due to the high surface area available in a CDS reactor, the evaporation rate of water from the slurry was modeled as constant-rate drying according to classic spray-dryer theory. However, the falling-rate and diffusion evaporation stages were negligible in CDS since sorbent particle bunching at the surface of the slurry is nonexistent.

  10. Tidally distorted exoplanets: Density corrections for short-period hot-Jupiters based solely on observable parameters

    SciTech Connect (OSTI)

    Burton, J. R.; Watson, C. A.; Fitzsimmons, A.; Moulds, V.; Pollacco, D.; Wheatley, P. J.; Littlefair, S. P.

    2014-07-10

    The close proximity of short-period hot-Jupiters to their parent star means they are subject to extreme tidal forces. This has a profound effect on their structure and, as a result, density measurements that assume that the planet is spherical can be incorrect. We have simulated the tidally distorted surface for 34 known short-period hot-Jupiters, assuming surfaces of constant gravitational equipotential for the planet, and the resulting densities have been calculated based only on observed parameters of the exoplanet systems. Comparing these results to the density values, assuming the planets are spherical, shows that there is an appreciable change in the measured density for planets with very short periods (typically less than two days). For one of the shortest-period systems, WASP-19b, we determine a decrease in bulk density of 12% from the spherical case and, for the majority of systems in this study, this value is in the range of 1%-5%. On the other hand, we also find cases where the distortion is negligible (relative to the measurement errors on the planetary parameters) even in the cases of some very short period systems, depending on the mass ratio and planetary radius. For high-density gas planets requiring apparently anomalously large core masses, density corrections due to tidal deformation could become important for the shortest-period systems.

  11. Long-term leaching test of incinerator bottom ash: Evaluation of Cu partition

    SciTech Connect (OSTI)

    Lin, Cheng-Fang Wu, Chung-Hsin; Liu, Yen-Chiun

    2007-07-01

    Two types of leaching tests were performed on the bottom ash from municipal solid waste incinerators. A short-term batch test specified by the America Nuclear Society (ANS) and long-term column tests with acetic acid (pH 5.2) as leaching solution were used to evaluate copper leachability. The Cu leaching after the 5-d ANS test is about 1% of the original Cu content of 5300 mg/kg. Upon addition of a stabilizing agent, the Cu leaching quantity is reduced; the extent of reduction depends on the type of chemical used (phosphate, carbonate and sulfide). The 1.6% Na{sub 2}S addition showed negligible Cu leaching, and Na{sub 2}S was, therefore, used in subsequent column tests. The 30-d column test indicates a steady increase of Cu leaching amount with time and reaches about 1.5% of the original Cu content after 30 d. A 180-d column test further increased the Cu leaching to about 5.1% of the original Cu content, whereas no appreciable Cu leaching was found with the addition of 1.6% Na{sub 2}S. A sequential extraction was conducted on the raw ash, ash with the addition of Na{sub 2}S and the residue ash after 30 d of operation to characterize Cu affinity for different solid fractions. The data were used to evaluate the fate of Cu through these interactions.

  12. Performance of pancake coils of parallel co-wound Ag/BSCCO tape conductors in static and ramped magnetic fields

    SciTech Connect (OSTI)

    Schwenterly, S.W.; Lue, J.W.; Lubell, M.S.; Walker, M.S.; Hazelton, D.W.; Haldar, P.; Rice, J.A.; Hoehn, J.G. Jr.; Motowidlo, L.R.

    1994-12-31

    Critical Currents are reported for several Ag/BSCCO single-pancake coils in static magnetic fields ranging from 0 to 5 T and temperatures from 4.2 K to 105 K. The sample coils were co-wound of one to six tape conductors in parallel. Since the closed loops formed in such an arrangement could lead to eddy current heating or instability in changing fields, one of the coils was also tested in helium gas, in fields ramped at rates of up to 1.5 T/s. For these quasi-adiabatic tests, at each temperature the transport current was set just below the critical value for a preset static field of 3.3 or 4.9 T. The field was then rapidly ramped down to zero, held for 20 sec, and then ramped back up to the original value. The maximum observed temperature transient of about 1.7 K occurred at 9 K, for a field change of 4.75 T. The temperature transients became negligible when the sample was immersed in liquid helium. Above 30 K, the transients were below 1 K. These results give confidence that parallel co-wound HTSC coils are stable in a rapidly-ramped magnetic field, without undue eddy current heating.

  13. Control of the polarization of a vacuum-ultraviolet, high-gain, free-electron laser

    SciTech Connect (OSTI)

    Allaria, Enrico; Diviacco, Bruno; Callegari, Carlo; Finetti, Paola; Mahieu, Benot; Viefhaus, Jens; Zangrando, Marco; De Ninno, Giovanni; Lambert, Guillaume; Ferrari, Eugenio; Buck, Jens; Ilchen, Markus; Vodungbo, Boris; Mahne, Nicola; Svetina, Cristian; Spezzani, Carlo; Di Mitri, Simone; Penco, Giuseppe; Trov, Mauro; Fawley, William M.; Rebernik, Primoz R.; Gauthier, David; Grazioli, Cesare; Coreno, Marcello; Ressel, Barbara; Kivimki, Antti; Mazza, Tommaso; Glaser, Leif; Scholz, Frank; Seltmann, Joern; Gessler, Patrick; Grnert, Jan; De Fanis, Alberto; Meyer, Michael; Knie, Andr; Moeller, Stefan P.; Raimondi, Lorenzo; Capotondi, Flavio; Pedersoli, Emanuele; Plekan, Oksana; Danailov, Miltcho B.; Demidovich, Alexander; Nikolov, Ivaylo; Abrami, Alessandro; Gautier, Julien; Lning, Jan; Zeitoun, Philippe; Giannessi, Luca

    2014-12-02

    The two single-pass, externally seeded free-electron lasers (FELs) of the FERMI user facility are designed around Apple-II-type undulators that can operate at arbitrary polarization in the vacuum ultraviolet-to-soft x-ray spectral range. Furthermore, within each FEL tuning range, any output wavelength and polarization can be set in less than a minute of routine operations. We report the first demonstration of the full output polarization capabilities of FERMI FEL-1 in a campaign of experiments where the wavelength and nominal polarization are set to a series of representative values, and the polarization of the emitted intense pulses is thoroughly characterized by three independent instruments and methods, expressly developed for the task. The measured radiation polarization is consistently >90% and is not significantly spoiled by the transport optics; differing, relative transport losses for horizontal and vertical polarization become more prominent at longer wavelengths and lead to a non-negligible ellipticity for an originally circularly polarized state. The results from the different polarimeter setups validate each other, allow a cross-calibration of the instruments, and constitute a benchmark for user experiments.

  14. Nonlinear interaction of fast particles with Alfven waves in toroidal plasmas

    SciTech Connect (OSTI)

    Candy, J.; Borba, D.; Huysmans, G.T.A.; Kerner, W.; Berk, H.L.

    1996-12-17

    A numerical algorithm to study the nonlinear, resonant interaction of fast particles with Alfven waves in tokamak geometry has been developed. The scope of the formalism is wide enough to describe the nonlinear evolution of fishbone modes, toroidicity-induced Alfven eigenmodes and ellipticity-induced Alfven eigenmodes, driven by both passing and trapped fast ions. When the instability is sufficiently weak, it is known that the wave-particle trapping nonlinearity will lead to mode saturation before wave-wave nonlinearities are appreciable. The spectrum of linear modes can thus be calculated using a magnetohydrodynamic normal-mode code, then nonlinearly evolved in time in an efficient way according to a two-time-scale Lagrangian dynamical wave model. The fast particle kinetic equation, including the effect of orbit nonlinearity arising from the mode perturbation, is simultaneously solved of the deviation, {delta}f = f {minus} f{sub 0}, from an initial analytic distribution f{sub 0}. High statistical resolution allows linear growth rates, frequency shifts, resonance broadening effects, and nonlinear saturation to be calculated quickly and precisely. The results have been applied to an ITER instability scenario. Results show that weakly-damped core-localized modes alone cause negligible alpha transport in ITER-like plasmas--even with growth rates one order of magnitude higher than expected values. However, the possibility of significant transport in reactor-type plasmas due to weakly unstable global modes remains an open question.

  15. A low cost, high energy density and long cycle life potassium-sulfur battery for grid-scale energy storage

    SciTech Connect (OSTI)

    Lu, Xiaochuan; Bowden, Mark E.; Sprenkle, Vincent L.; Liu, Jun

    2015-08-15

    Alkali metal-sulfur batteries are attractive for energy storage applications because of their high energy density. Among the batteries, lithium-sulfur batteries typically use liquid in the battery electrolyte, which causes problems in both performance and safety. Sodium-sulfur batteries can use a solid electrolyte such as beta alumina but this requires a high operating temperature. Here we report a novel potassium-sulfur battery with K+-conducting beta-alumina as the electrolyte. Our studies indicate that liquid potassium exhibits much better wettability on the surface of beta-alumina compared to liquid sodium at lower temperatures. Based on this observation, we develop a potassium-sulfur battery that can operate at as low as 150C with excellent performance. In particular, the battery shows excellent cycle life with negligible capacity fade in 1000 cycles because of the dense ceramic membrane. This study demonstrates a new battery with a high energy density, long cycle life, low cost and high safety, which is ideal for grid-scale energy storage.

  16. THE CLOSEST KNOWN FLYBY OF A STAR TO THE SOLAR SYSTEM

    SciTech Connect (OSTI)

    Mamajek, Eric E.; Barenfeld, Scott A.; Ivanov, Valentin D.; Boffin, Henri M. J.; Kniazev, Alexei Y.; Visnen, Petri; Beletsky, Yuri

    2015-02-10

    Passing stars can perturb the Oort Cloud, triggering comet showers and potentially extinction events on Earth. We combine velocity measurements for the recently discovered, nearby, low-mass binary system WISE J072003.20-084651.2 (Scholzs star) to calculate its past trajectory. Integrating the Galactic orbits of this ?0.15 M{sub ?} binary system and the Sun, we find that the binary passed within only 52{sup +23}{sub ?14} kAU (0.25{sup +0.11}{sub ?0.07} pc) of the Sun 70{sup +15}{sub ?10} kya (1? uncertainties), i.e., within the outer Oort Cloud. This is the closest known encounter of a star to our solar system with a well-constrained distance and velocity. Previous work suggests that flybys within 0.25 pc occur infrequently (?0.1 Myr{sup ?1}). We show that given the low mass and high velocity of the binary system, the encounter was dynamically weak. Using the best available astrometry, our simulations suggest that the probability that the star penetrated the outer Oort Cloud is ?98%, but the probability of penetrating the dynamically active inner Oort Cloud (<20 kAU) is ?10{sup ?4}. While the flyby of this system likely caused negligible impact on the flux of long-period comets, the recent discovery of this binary highlights that dynamically important Oort Cloud perturbers may be lurking among nearby stars.

  17. Cosmology from Cosmic Shear with DES Science Verification Data

    SciTech Connect (OSTI)

    Abbott, T.

    2015-07-20

    We present the first constraints on cosmology from the Dark Energy Survey (DES), using weak lensing measurements from the preliminary Science Verification (SV) data. We use 139 square degrees of SV data, which is less than 3% of the full DES survey area. Using cosmic shear 2-point measurements over three redshift bins we find ?8(m=0.3)0.5 = 0:81 0:06 (68% confidence), after marginalising over 7 systematics parameters and 3 other cosmological parameters. Furthermore, we examine the robustness of our results to the choice of data vector and systematics assumed, and find them to be stable. About 20% of our error bar comes from marginalising over shear and photometric redshift calibration uncertainties. The current state-of-the-art cosmic shear measurements from CFHTLenS are mildly discrepant with the cosmological constraints from Planck CMB data. Our results are consistent with both datasets. Our uncertainties are ~30% larger than those from CFHTLenS when we carry out a comparable analysis of the two datasets, which we attribute largely to the lower number density of our shear catalogue. We investigate constraints on dark energy and find that, with this small fraction of the full survey, the DES SV constraints make negligible impact on the Planck constraints. The moderate disagreement between the CFHTLenS and Planck values of ?8(?m=0.3)0.5 is present regardless of the value of w.

  18. Parametric instability of a monochromatic Alfven wave: Perpendicular decay in low beta plasma

    SciTech Connect (OSTI)

    Gao, Xinliang; Lu, Quanming; Shan, Lican; Wang, Shui; Li, Xing

    2013-07-15

    Two-dimensional hybrid simulations are performed to investigate the parametric decay of a monochromatic Alfven wave in low beta plasma. Both the linearly and left-hand polarized pump Alfven waves are considered in the paper. For the linearly polarized pump Alfven wave, either a parallel or obliquely propagating wave can lead to the decay along the perpendicular direction. Initially, the parametric decay takes place along the propagating direction of the pump wave, and then the decay occurs in the perpendicular direction. With the increase of the amplitude and the propagating angle of the pump wave (the angle between the propagating direction of the pump wave and the ambient magnetic field), the spectral range of the excited waves becomes broad in the perpendicular direction. But the effects of the plasma beta on the spectral range of the excited waves in perpendicular direction are negligible. However, for the left-hand polarized pump Alfven wave, when the pump wave propagates along the ambient magnetic field, the parametric decay occurs nearly along the ambient magnetic field, and there is no obvious decay in the perpendicular direction. Significant decay in the perpendicular direction can only be found when the pump wave propagates obliquely.

  19. Composition and Bonding in Amorphous Carbon Films Grown by Ion Beam Assisted Deposition: Influence of the Assistance Voltage

    SciTech Connect (OSTI)

    Albella, J.M.; Banks, J.C.; Climent-Font, A.; Doyle, B.L.; Gago, R.; Jimenez, I.; Terminello, L.J.

    1998-11-12

    Amorphous carbon films have been grown by evaporation of graphite with concurrent Ar+ ions bombardment assistance. The ion energy has been varied between 0-800 V while keeping a constant ion to carbon atom arrival ratio. Film composition and density were determined by ion scattering techniques (RBS and ERDA), indicating a negligible hydrogen content and a density dependence with the assistance voltage. The bonding structure of the films has been studied by Raman and X-ray Absorption Near-Edge (XANES) spectroscopy. Different qualitative effects have been found depending on the ion energy range. For ion energies below 300 eV, there is a densification of the carbon layer due to the increase in the sp3 content. For ion energies above 300 eV sputtering phenomena dominate over densification, and thinner films are found with increasing assistance voltage until no film is grown over 600 V. The films with the highest SP3 content are grown with intermediate energies between 200-300 V.

  20. Indirect detection of gravitino dark matter including its three-body decays

    SciTech Connect (OSTI)

    Choi, Ki-Young; Restrepo, Diego; Yaguna, Carlos E.; Zapata, Oscar E-mail: restrepo@udea.edu.co E-mail: pfozapata@eia.edu.co

    2010-10-01

    It was recently pointed out that in supersymmetric scenarios with gravitino dark matter and bilinear R-parity violation, gravitinos with masses below M{sub W} typically decay with a sizable branching ratio into the 3-body final states W*l and Z*?. In this paper we study the indirect detection signatures of gravitino dark matter including such final states. First, we obtain the gamma ray spectrum from gravitino decays, which features a monochromatic contribution from the decay into ?? and a continuum contribution from the three-body decays. After studying its dependence on supersymmetric parameters, we compute the expected gamma ray fluxes and derive new constraints, from recent FERMI data, on the R-parity breaking parameter and on the gravitino lifetime. Indirect detection via antimatter searches, a new possibility brought about by the three-body final states, is also analyzed. For models compatible with the gamma ray observations, the positron signal is found to be negligible whereas the antiproton one can be significant.

  1. On the Issue of the {zeta} series convergence and loop corrections in the generation of observable primordial non-Gaussianity in slow-roll inflation. II. The trispectrum

    SciTech Connect (OSTI)

    Rodriguez, Yeinzon; Valenzuela-Toledo, Cesar A.

    2010-01-15

    We calculate the trispectrum T{sub {zeta}}of the primordial curvature perturbation {zeta}, generated during a slow-roll inflationary epoch by considering a two-field quadratic model of inflation with canonical kinetic terms. We consider loop contributions as well as tree-level terms, and show that it is possible to attain very high, including observable, values for the level of non-Gaussianity {tau}{sub NL} if T{sub {zeta}}is dominated by the one-loop contribution. Special attention is paid to the claim in J. Cosmol. Astropart. Phys. 02 (2009) 017 that, in the model studied in this paper and for the specific inflationary trajectory we choose, the quantum fluctuations of the fields overwhelm the classical evolution. We argue that such a claim actually does not apply to our model, although more research is needed in order to understand the role of quantum diffusion. We also consider the probability that an observer in an ensemble of realizations of the density field sees a non-Gaussian distribution. In that respect, we show that the probability associated to the chosen inflationary trajectory is non-negligible. Finally, the levels of non-Gaussianity f{sub NL} and {tau}{sub NL} in the bispectrum B{sub {zeta}}and trispectrum T{sub {zeta}}of {zeta}, respectively, are also studied for the case in which {zeta} is not generated during inflation.

  2. Melt-spin processing of high {Tc} oxide superconductors

    SciTech Connect (OSTI)

    Folkerts, T.J.; Wu, Hengning; Yoo, S.I.; Merkle, B.D.; Arrasmith, S.R.; Dennis, K.W.; Kramer, M.J.; McCallum, R.W.

    1993-10-01

    Containerless techniques offer distinct advantages for the melt processing of oxide superconductors. The majority of these materials form liquids which are highly reactive with standard crucible materials such as Al{sub 2}O{sub 3} and Pt, resulting in non-negligible contamination. We have developed a containerless melt-spin processing technique where in 50--400 {mu}m particles of REBa{sub 2}Cu{sub 3}O{sub 7-x} high temperature oxide superconductors are melted in free fall through a vertical tube furnace and quenched onto a copper wheel. Previously this method has been successful in producing glasses of NdBa{sub 2}Cu{sub 3}O{sub 7-x} and GdBa{sub 2}Cu{sub 3}O{sub 7-x}. In this report we discuss the results for both stoichiometric and non-stoichiometric YBa{sub 2}Cu{sub 3}O{sub 7-x} (Y123). Thermal, microstructural, and superconducting characterization of both the as-quenched and the annealed materials will be presented.

  3. Direct observation of intrinsic piezoelectricity of Pb(Zr,Ti)O{sub 3} by time-resolved x-ray diffraction measurement using single-crystalline films

    SciTech Connect (OSTI)

    Fujisawa, Takashi; Ehara, Yoshitaka; Yasui, Shintaro; Kamo, Takafumi; Funakubo, Hiroshi; Yamada, Tomoaki; Sakata, Osami

    2014-07-07

    Lead zirconate titanate, Pb(Zr,Ti)O{sub 3} or PZT, is one of the most widely investigated ferroelectric and piezoelectric materials due to its superior properties. However, the intrinsic properties of PZT have not been directly measured due to the lack of fabrication of single crystals even though a basic understanding of intrinsic properties has been of interest developing lead-free piezoelectric materials. We demonstrated the direct observation of the intrinsic piezoelectric property by means of the detection of electric-field induced crystal lattice distortion of thick Pb(Zr{sub 0.35}Ti{sub 0.65})O{sub 3} single-crystalline films with single polar-axis orientation and negligible residual strain using the time-resolved X-ray diffraction (XRD) together with the polarization response. Consequently, the effective converse piezoelectric response was experimentally revealed; hence, the electrostrictive coefficient, which is the conversion coefficient between the electrical and mechanical response, was determined. The obtained effective electrostrictive coefficient was 5.26.3??10{sup ?2} m{sup 4}/C{sup 2}, which agrees with theoretical prediction.

  4. Accurate calculations of the WIMP halo around the Sun and prospects for its gamma-ray detection

    SciTech Connect (OSTI)

    Sivertsson, Sofia; Edsjoe, Joakim

    2010-03-15

    Galactic weakly interacting massive particles (WIMPs) may scatter off solar nuclei to orbits gravitationally bound to the Sun. Once bound, the WIMPs continue to lose energy by repeated scatters in the Sun, eventually leading to complete entrapment in the solar interior. While the density of the bound population is highest at the center of the Sun, the only observable signature of WIMP annihilations inside the Sun is neutrinos. It has been previously suggested that although the density of WIMPs just outside the Sun is lower than deep inside, gamma rays from WIMP annihilation just outside the surface of the Sun, in the so-called WIMP halo around the Sun, may be more easily detected. We here revisit this problem using detailed Monte Carlo simulations and detailed composition and structure information about the Sun to estimate the size of the gamma-ray flux. Compared to earlier simpler estimates, we find that the gamma-ray flux from WIMP annihilations in the solar WIMP halo would be negligible; no current or planned detectors would be able to detect this flux.

  5. Microscopic description of anisotropic low-density dipolar Bose gases in two dimensions

    SciTech Connect (OSTI)

    Macia, A.; Mazzanti, F.; Boronat, J.; Zillich, R. E.

    2011-09-15

    A microscopic description of the zero-energy two-body ground state and many-body static properties of anisotropic homogeneous gases of bosonic dipoles in two dimensions at low densities is presented and discussed. By changing the polarization angle with respect to the plane, we study the impact of the anisotropy, present in the dipole-dipole interaction, on the energy per particle, comparing the results with mean-field predictions. We restrict the analysis to the regime where the interaction is always repulsive, although the strength of the repulsion depends on the orientation with respect to the polarization field. We present a series expansion of the solution of the zero-energy two-body problem, which allows us to find the scattering length of the interaction and to build a suitable Jastrow factor that we use as a trial wave function for both a variational and diffusion Monte Carlo simulation of the infinite system. We find that the anisotropy has an almost negligible impact on the ground-state properties of the many-body system in the universal regime where the scattering length governs the physics of the system. We also show that scaling in the gas parameter persists in the dipolar case up to values where other isotropic interactions with the same scattering length yield different predictions.

  6. High power impulse magnetron sputtering: Current-voltage-timecharacteristics indicate the onset of sustained self-sputtering

    SciTech Connect (OSTI)

    Anders, Andre; Andersson, Joakim; Ehiasarian, Arutiun

    2007-08-03

    The commonly used current-voltage characteristics are foundinadequate for describing the pulsed nature of the high power impulsemagnetron sputtering (HIPIMS) discharge, rather, the description needs tobe expanded to current-voltage-time characteristics for each initial gaspressure. Using different target materials (Cu, Ti, Nb, C, W, Al, Cr) anda pulsed constant-voltage supply it is shown that the HIPIMS dischargestypically exhibit an initial pressure dependent current peak followed bya second phase that is power and material dependent. This suggests thatthe initial phase of a HIPIMS discharge pulse is dominated by gas ionswhereas the later phase has a strong contribution from self-sputtering.For some materials the discharge switches into a mode of sustainedself-sputtering. The very large differences between materials cannot beascribed to the different sputter yields but they indicate thatgeneration and trapping ofsecondary electrons plays a major role forcurrent-voltage-time characteristics. In particular, it is argued thatthe sustained self-sputtering phase is associated with thegeneration ofmultiply charged ions because only they can cause potential emission ofsecondary electrons whereas the yield caused by singly charged metal ionsis negligibly small.

  7. Extrinsic Sources of Scatter in the Richness-Mass Relation of Galaxy Clusters

    SciTech Connect (OSTI)

    Rozo, Eduardo; Rykoff, Eli; Koester, Benjamin; Nord, Brian; Wu, Hao-Yi; Evrard, August; Wechsler, Risa; /KIPAC, Menlo Park /Stanford U., Phys. Dept.

    2012-03-27

    Maximizing the utility of upcoming photometric cluster surveys requires a thorough understanding of the richness-mass relation of galaxy clusters. We use Monte Carlo simulations to study the impact of various sources of observational scatter on this relation. Cluster ellipticity, photometric errors, photometric redshift errors, and cluster-to-cluster variations in the properties of red-sequence galaxies contribute negligible noise. Miscentering, however, can be important, and likely contributes to the scatter in the richness - mass relation of galaxy maxBCG clusters at the low mass end, where centering is more difficult. We also investigate the impact of projection effects under several empirically motivated assumptions about cluster environments. Using SDSS data and the maxBCG cluster catalog, we demonstrate that variations in cluster environments can rarely ({approx} 1%-5% of the time) result in significant richness boosts. Due to the steepness of the mass/richness function, the corresponding fraction of optically selected clusters that suffer from these projection effects is {approx} 5%-15%. We expect these numbers to be generic in magnitude, but a precise determination requires detailed, survey-specific modeling.

  8. Upscaling of U(VI) Desorption and Transport from Decimeter-Scale Heterogeneity to Plume-Scale Modeling

    SciTech Connect (OSTI)

    Curtis, Gary P; Kohler, Matthias; Kannappan, Ramakrishnan; Briggs, Martin; Day-Lewis, Fred

    2015-02-24

    Reactive solute transport in aquifers is commonly affected by rate limited mass transfer. This slow mass transfer can exhibit significant control on the times required to restore contaminated aquifers to near-pristine conditions under both ambient and forced-gradient flow systems and is therefore important to understand. Both nonreactive and reactive tracer experiments provide valuable insight into the exchange of solute between mobile and immobile porosity. At the grain scale and column scale, mass transfer limitations were manifested as a concentration rebound when contaminated sediments were contacted with pristine groundwater. This behavior was successfully modeled using the multirate mass transfer model. Mass transfer observed in a 2 m long intermediate laboratory scale experiment showed significant concentration rebound in the first half meter along a flowpath through the tank and negligible rebound near the exit of the tank. Experimental observations and model simulations show that although concentration rebound was small at the end of the tank, the overall elution of uranium from of the tank was still controlled by mass transfer which was manifested by a long tail. At the field scale, mass transfer parameters inferred from geo-electrical measurements of bulk conductivity and traditional conductivity measurements of fluid samples showed significant spatial variability. Overall the improved understanding of mass transfer across multiple scales should lead to more robust reactive transport simulations and site management.

  9. Layering and temperature-dependent magnetization and anisotropy of naturally produced Ni/NiO multilayers

    SciTech Connect (OSTI)

    Pappas, S. D.; Trachylis, D.; Velgakis, M. J.; Kapaklis, V.; Joensson, P. E.; Papaioannou, E. Th.; Delimitis, A.; Poulopoulos, P.; Fumagalli, P.; Politis, C.

    2012-09-01

    Ni/NiO multilayers were grown by magnetron sputtering at room temperature, with the aid of the natural oxidation procedure. That is, at the end of the deposition of each single Ni layer, air is let to flow into the vacuum chamber through a leak valve. Then, a very thin NiO layer ({approx}1.2 nm) is formed. Simulated x-ray reflectivity patterns reveal that layering is excellent for individual Ni-layer thickness larger than 2.5 nm, which is attributed to the intercalation of amorphous NiO between the polycrystalline Ni layers. The magnetization of the films, measured at temperatures 5-300 K, has almost bulk-like value, whereas the films exhibit a trend to perpendicular magnetic anisotropy (PMA) with an unusual significant positive interface anisotropy contribution, which presents a weak temperature dependence. The power-law behavior of the multilayers indicates a non-negligible contribution of higher order anisotropies in the uniaxial anisotropy. Bloch-law fittings for the temperature dependence of the magnetization in the spin-wave regime show that the magnetization in the multilayers decreases faster as a function of temperature than the one of bulk Ni. Finally, when the individual Ni-layer thickness decreases below 2 nm, the multilayer stacking vanishes, resulting in a dramatic decrease of the interface magnetic anisotropy and consequently in a decrease of the perpendicular magnetic anisotropy.

  10. Household energy use in urban Venezuela: Implications from surveys in Maracaibo, Valencia, Merida, and Barcelona-Puerto La Cruz

    SciTech Connect (OSTI)

    Figueroa, M.J.; Sathaye, J.

    1993-08-01

    This report identifies the most important results of a comparative analysis of household commercial energy use in Venezuelan urban cities. The use of modern fuels is widespread among all cities. Cooking consumes the largest share of urban household energy use. The survey documents no use of biomass and a negligible use of kerosene for cooking. LPG, natural gas, and kerosene are the main fuels available. LPG is the fuel choice of low-income households in all cities except Maracaibo, where 40% of all households use natural gas. Electricity consumption in Venezuela`s urban households is remarkably high compared with the levels used in households in comparable Latin American countries and in households of industrialized nations which confront harsher climatic conditions and, therefore, use electricity for water and space heating. The penetration of appliances in Venezuela`s urban households is very high. The appliances available on the market are inefficient, and there are inefficient patterns of energy use among the population. Climate conditions and the urban built form all play important roles in determining the high level of energy consumption in Venezuelan urban households. It is important to acknowledge the opportunities for introducing energy efficiency and conservation in Venezuela`s residential sector, particularly given current economic and financial constraints, which may hamper the future provision of energy services.

  11. Estimated Uncertainties in the Idaho National Laboratory Matched-Index-of-Refraction Lower Plenum Experiment

    SciTech Connect (OSTI)

    Donald M. McEligot; Hugh M. McIlroy, Jr.; Ryan C. Johnson

    2007-11-01

    The purpose of the fluid dynamics experiments in the MIR (Matched-Index-of-Refraction) flow system at Idaho National Laboratory (INL) is to develop benchmark databases for the assessment of Computational Fluid Dynamics (CFD) solutions of the momentum equations, scalar mixing, and turbulence models for typical Very High Temperature Reactor (VHTR) plenum geometries in the limiting case of negligible buoyancy and constant fluid properties. The experiments use optical techniques, primarily particle image velocimetry (PIV) in the INL MIR flow system. The benefit of the MIR technique is that it permits optical measurements to determine flow characteristics in passages and around objects to be obtained without locating a disturbing transducer in the flow field and without distortion of the optical paths. The objective of the present report is to develop understanding of the magnitudes of experimental uncertainties in the results to be obtained in such experiments. Unheated MIR experiments are first steps when the geometry is complicated. One does not want to use a computational technique, which will not even handle constant properties properly. This report addresses the general background, requirements for benchmark databases, estimation of experimental uncertainties in mean velocities and turbulence quantities, the MIR experiment, PIV uncertainties, positioning uncertainties, and other contributing measurement uncertainties.

  12. Multifunctional Properties of Cyanate Ester Composites with SiO2 Coated Fe3O4 Fillers

    SciTech Connect (OSTI)

    Sun, Weixing; Sun, Wuzhu; Kessler, Michael R.; Bowler, Nicola; Dennis, Kevin W.; McCallum, R. William; Li, Qi; Tan, Xiaoli

    2013-02-22

    SiO2 coated Fe3O4 submicrometer spherical particles (a conducting core/insulating shell configuration) are fabricated using a hydrothermal method and are loaded at 10 and 20 vol % into a bisphenol E cyanate ester matrix for synthesis of multifunctional composites. The dielectric constant of the resulting composites is found to be enhanced over a wide frequency and temperature range while the low dielectric loss tangent of the neat cyanate ester polymer is largely preserved up to 160 ?C due to the insulating SiO2 coating on individual conductive Fe3O4 submicrometer spheres. These composites also demonstrate high dielectric breakdown strengths at room temperature. Dynamic mechanical analysis indicates that the storage modulus of the composite with a 20 vol % filler loading is twice as high as that of neat resin, but the glass transition temperature considerably decreases with increasing filler content. Magnetic measurements reveal a large saturation magnetization and negligibly low coercivity and remanent magnetization in these composites.

  13. Effect of moisture on the traction-separation behavior of cellulose nanocrystal interfaces

    SciTech Connect (OSTI)

    Sinko, Robert; Keten, Sinan

    2014-12-15

    Interfaces and stress transfer between cellulose nanocrystals (CNCs) dictate the mechanical properties of hierarchical cellulose materials such as neat films and nanocomposites. An interesting question that remains is how the behavior of these interfaces changes due to environmental stimuli, most notably moisture. We present analyses on the traction-separation behavior between I? CNC elementary fibrils, providing insight into how the presence of a single atomic layer of water at these interfaces can drastically change the mechanical behavior. We find that molecular water at the interface between hydrophilic CNC surfaces has a negligible effect on the tensile separation adhesion energy. However, when water cannot hydrogen bond easily to the surface (i.e., hydrophobic surface), it tends to maintain hydrogen bonds with other water molecules across the interface and form a capillary bridge that serves to increase the energy required to separate the crystals. Under shear loading, water lowers the energy barriers to sliding by reducing the atomic friction and consequently the interlayer shear modulus between crystals. Our simulations indicate that these nanoscale interfaces and physical phenomena such as interfacial adhesion, interlayer shear properties, and stick-slip friction behavior can be drastically altered by the presence of water.

  14. Cement paste prior to setting: A rheological approach

    SciTech Connect (OSTI)

    Bellotto, Maurizio

    2013-10-15

    The evolution of cement paste during the dormant period is analyzed via small amplitude oscillation rheological measurements. Cement paste, from the very first moments after mixing cement and water, shows the formation of an elastic gel whose strength is rapidly increasing over time. Up to the onset of Portlandite precipitation G?(t) increases by more than 2 orders of magnitude and in the acceleratory period G?(t) continues steadily to increase. A microstructural modification is likely to occur between the dormant and the acceleratory period. At low deformations in the linearity domain the storage modulus G?(?) exhibits a negligible frequency dependence. At higher deformations cement paste shows a yield stress which increases on increasing paste concentration. The presence of superplasticizers decreases the yield stress and increases the gelation threshold of the paste. Above the gelation threshold the evolution of cement paste with superplasticizers follows similar trends to the neat paste. -- Highlights: The gelation of cement paste during the dormant period is analyzed via rheometry. The observed evolution is proposed to be related to the pore structure refinement. Similarities are observed with colloidal gels and colloidal glasses.

  15. Amplifying Real Estate Value through Energy&WaterManagement: From ESCO to 'Energy Services Partner'

    SciTech Connect (OSTI)

    Mills, Evan

    2004-06-08

    The energy service company (ESCO) business model could become significantly more effective by integrating the energy-efficiency purveyor and their capital into the underlying building ownership and operation partnership, rather than the current model in which the ESCO remains an outsider with higher transaction costs and limited interest and participation in the value created by the cost savings. Resource conservation advocates rarely use the language of real estate to articulate the cost effectiveness of capital improvements aimed at reducing utility costs in commercial and residential income properties. Conventional methods that rely on rarefied academic notions of simple payback time or a narrow definition of return on investment fail to capture a significant component of the true market value created by virtue of reduced operating expenses. Improvements in energy and water efficiency can increase the fundamental profitability of real estate investments by raising Net Operating Income (NOI), and hence returns during the holding period, and, ultimately, proceeds at time of sale. We introduce the concept of an Energy Services Partner, who takes an equity interest in a real estate partnership in exchange for providing the expertise and capital required to reduce utility operating costs. Profit to all partners increases considerably as a result. This approach would also help to address a crisis facing ESCOs today stemming from their considerable liabilities (through guaranteed savings) and negligible offsetting assets.

  16. Probing dark matter self-interaction in the Sun with IceCube-PINGU

    SciTech Connect (OSTI)

    Chen, Chian-Shu; Lee, Fei-Fan; Lin, Guey-Lin; Lin, Yen-Hsun E-mail: fflee@mail.nctu.edu.tw E-mail: chris.py99g@g2.nctu.edu.tw

    2014-10-01

    We study the capture, annihilation and evaporation of dark matter (DM) inside the Sun. It has been shown that the DM self-interaction can increase the DM number inside the Sun. We demonstrate that this enhancement becomes more significant in the regime of small DM mass, given a fixed DM self-interaction cross section. This leads to the enhancement of neutrino flux from DM annihilation. On the other hand, for DM mass as low as as a few GeVs, not only the DM-nuclei scatterings can cause the DM evaporation, DM self-interaction also provides non-negligible contributions to this effect. Consequently, the critical mass for DM evaporation (typically 3 ? 4 GeV without the DM self-interaction) can be slightly increased. We discuss the prospect of detecting DM self-interaction in IceCube-PINGU using the annihilation channels ????{sup +}?{sup -},??-bar as examples. The PINGU sensitivities to DM self-interaction cross section ?{sub ??} are estimated for track and cascade events.

  17. Kinetic mix mechanisms in shock-driven inertial confinement fusion implosions

    SciTech Connect (OSTI)

    Rinderknecht, H. G.; Sio, H.; Li, C. K.; Hoffman, N.; Zylstra, A. B.; Rosenberg, M. J.; Frenje, J. A.; Gatu Johnson, M.; Seguin, F. H.; Petrasso, R. D.; Betti, R.; Yu Glebov, V.; Meyerhofer, D. D.; Sangster, T. C.; Seka, W.; Stoeckl, C.; Kagan, G.; Molvig, K.; Bellei, C.; Amendt, P.; Landen, O.; Rygg, J. R.; Smalyuk, V. A.; Wilks, S.; Greenwood, A.; Nikroo, A.

    2014-05-19

    Shock-driven implosions of thin-shell capsules, or ''exploding pushers,'' generate low-density, high-temperature plasmas in which hydrodynamic instability growth is negligible and kinetic effects can play an important role. Data from implosions of thin deuterated-plastic shells with hydroequivalent D3He gas fills ranging from pure deuterium to pure 3He [H. G. Rinderknecht et al., Phys. Rev. Lett. 112, 135001 (2014)] were obtained to evaluate non-hydrodynamic fuel-shell mix mechanisms. Simulations of the experiments including reduced ion kinetic models support ion diffusion as an explanation for these data. Several additional kinetic mechanisms are investigated and compared to the data to determine which are important in the experiments. Shock acceleration of shell deuterons is estimated to introduce mix less than or comparable to the amount required to explain the data. Beam-target mechanisms are found to produce yields at most an order of magnitude less than the observations

  18. Investigation of Spatial Variation of Sea States Offshore of Humboldt Bay CA Using a Hindcast Model.

    SciTech Connect (OSTI)

    Dallman, Ann Renee; Neary, Vincent Sinclair

    2014-10-01

    Spatial variability of sea states is an important consideration when performing wave resource assessments and wave resource characterization studies for wave energy converter (WEC) test sites and commercial WEC deployments. This report examines the spatial variation of sea states offshore of Humboldt Bay, CA, using the wave model SWAN . The effect of depth and shoaling on bulk wave parameters is well resolved using the model SWAN with a 200 m grid. At this site, the degree of spatial variation of these bulk wave parameters, with shoaling generally perpendicular to the depth contours, is found to depend on the season. The variation in wave height , for example, was higher in the summer due to the wind and wave sheltering from the protruding land on the coastline north of the model domain. Ho wever, the spatial variation within an area of a potential Tier 1 WEC test site at 45 m depth and 1 square nautical mile is almost negligible; at most about 0.1 m in both winter and summer. The six wave characterization parameters recommended by the IEC 6 2600 - 101 TS were compared at several points along a line perpendicular to shore from the WEC test site . As expected, these parameters varied based on depth , but showed very similar seasonal trends.

  19. Reconstruction of a yeast cell from x-ray diffraction data

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Thibault, Pierre; Elser, Veit; Jacobsen, Chris; Shapiro, David; Sayre, David

    2006-06-21

    We provide details of the algorithm used for the reconstruction of yeast cell images in the recent demonstration of diffraction microscopy by Shapiro, Thibault, Beetz, Elser, Howells, Jacobsen, Kirz, Lima, Miao, Nieman & Sayre. Two refinements of the iterative constraint-based scheme are developed to address the current experimental realities of this imaging technique, which include missing central data and noise. A constrained power operator is defined whose eigenmodes allow the identification of a small number of degrees of freedom in the reconstruction that are negligibly constrained as a result of the missing data. To achieve reproducibility in the algorithm's output,more » a special intervention is required for these modes. Weak incompatibility of the constraints caused by noise in both direct and Fourier space leads to residual phase fluctuations. This problem is addressed by supplementing the algorithm with an averaging method. The effect of averaging may be interpreted in terms of an effective modulation transfer function, as used in optics, to quantify the resolution. The reconstruction details are prefaced with simulations of wave propagation through a model yeast cell. These show that the yeast cell is a strong-phase-contrast object for the conditions in the experiment.« less

  20. Can p-channel tunnel field-effect transistors perform as good as n-channel?

    SciTech Connect (OSTI)

    Verhulst, A. S. Pourghaderi, M. A.; Collaert, N.; Thean, A. V.-Y.; Verreck, D.; Van de Put, M.; Groeseneken, G.; Sore, B.

    2014-07-28

    We show that bulk semiconductor materials do not allow perfectly complementary p- and n-channel tunnel field-effect transistors (TFETs), due to the presence of a heavy-hole band. When tunneling in p-TFETs is oriented towards the gate-dielectric, field-induced quantum confinement results in a highest-energy subband which is heavy-hole like. In direct-bandgap IIIV materials, the most promising TFET materials, phonon-assisted tunneling to this subband degrades the subthreshold swing and leads to at least 10 smaller on-current than the desired ballistic on-current. This is demonstrated with quantum-mechanical predictions for p-TFETs with tunneling orthogonal to the gate, made out of InP, In{sub 0.53}Ga{sub 0.47}As, InAs, and a modified version of In{sub 0.53}Ga{sub 0.47}As with an artificially increased conduction-band density-of-states. We further show that even if the phonon-assisted current would be negligible, the build-up of a heavy-hole-based inversion layer prevents efficient ballistic tunneling, especially at low supply voltages. For p-TFET, a strongly confined n-i-p or n-p-i-p configuration is therefore recommended, as well as a tensily strained line-tunneling configuration.

  1. Is the effect of the Sun's gravitational potential on dark matter particles observable?

    SciTech Connect (OSTI)

    Bozorgnia, Nassim; Schwetz, Thomas E-mail: schwetz@fysik.su.se

    2014-08-01

    We consider the effect of the Sun's gravitational potential on the local phase space distribution of dark matter particles, focusing on its implication for the annual modulation signal in direct detection experiments. We perform a fit to the modulation signal observed in DAMA/LIBRA and show that the allowed region shrinks if Solar gravitational focusing (GF) is included compared to the one without GF. Furthermore, we consider a possible signal in a generic future direct detection experiment, irrespective of the DAMA/LIBRA signal. Even for scattering cross sections close to the current bound and a large exposure of a xenon target with 270 ton yr it will be hard to establish the presence of GF from data. In the region of dark matter masses below 40 GeV an annual modulation signal can be established for our assumed experimental setup, however GF is negligible for low masses. In the high mass region, where GF is more important, the significance of annual modulation itself is very low. We obtain similar results for lighter targets such as Ge and Ar. We comment also on inelastic scattering, noting that GF becomes somewhat more important for exothermic scattering compared to the elastic case.

  2. Lattice-Mismatched GaAs/InGaAs Two-Junction Solar Cells by Direct Wafer Bonding

    SciTech Connect (OSTI)

    Tanabe, K.; Aiken, D. J.; Wanlass, M. W.; Morral, A. F.; Atwater, H. A.

    2006-01-01

    Direct bonded interconnect between subcells of a lattice-mismatched III-V compound multijunction cell would enable dislocation-free active regions by confining the defect network needed for lattice mismatch accommodation to tunnel junction interfaces, while metamorphic growth inevitably results in less design flexibility and lower material quality than is desirable. The first direct-bond interconnected multijunction solar cell, a two-terminal monolithic GaAs/InGaAs two-junction solar cell, is reported and demonstrates viability of direct wafer bonding for solar cell applications. The tandem cell open-circuit voltage was approximately the sum of the subcell open-circuit voltages. This achievement shows direct bonding enables us to construct lattice-mismatched III-V multijunction solar cells and is extensible to an ultrahigh efficiency InGaP/GaAs/InGaAsP/InGaAs four-junction cell by bonding a GaAs-based lattice-matched InGaP/GaAs subcell and an InP-based lattice-matched InGaAsP/InGaAs subcell. The interfacial resistance experimentally obtained for bonded GaAs/InP smaller than 0.10 Ohm-cm{sup 2} would result in a negligible decrease in overall cell efficiency of {approx}0.02%, under 1-sun illumination.

  3. Impacts of a high-burnup spent fuel on a geological disposal system design

    SciTech Connect (OSTI)

    Cho, D.K.; Lee, Y.; Lee, J.Y.; Choi, H.J.; Choi, J.W. [Korea Atomic Energy Research Institute, Yuseong-gu, Daejeon-city (Korea, Republic of)

    2007-07-01

    The influence of a burnup increase of a spent nuclear fuel on a deep geological disposal system was evaluated in this study. First, the impact of a burnup increase on each aspect related to thermal and nuclear safety concerns was quantified. And then, the tunnel length, excavation volume, and the raw materials for a cast insert, copper, bentonite, and backfill needed to constitute a disposal system were comprehensively analyzed based on the spent fuel inventory to generate 1 Terawatt-year (TWa), to establish the overall effects and consequences on a geological disposal. As a result, impact of a burnup increase on the criticality safety and radiation shielding was shown to be negligible. The disposal area, however, is considerably affected because of a higher thermal load. And, it is reasonable to use a canister such as the Korean Reference Disposal Canister (KDC-1) containing 4 spent fuels up to 50 GWD/MtU, and to use a canister containing 3 spent fuels beyond 50 GWD/MtU. Although a considerable increased, 33 % in the tunnel length and 30 % in the excavation volume, was observed as the burnup increases from 50 to 60 GWD/MtU, because a decrease in the canister needs can offset an increase in the excavation volume, it can be concluded that a burnup increase of a spent fuel is not a critical concern for a geological disposal of a spent fuel. (authors)

  4. Using Atmosphere-Forest Measurements To Examine The Potential For Reduced Downwind Dose

    SciTech Connect (OSTI)

    Viner, B.

    2015-10-13

    A 2-D dispersion model was developed to address how airborne plumes interact with the forest at Savannah River Site. Parameters describing turbulence and mixing of the atmosphere within and just above the forest were estimated using measurements of water vapor or carbon dioxide concentration made at the Aiken AmeriFlux tower for a range of stability and seasonal conditions. Stability periods when the greatest amount of mixing of an airborne plume into the forest were found for 1) very unstable environments, when atmospheric turbulence is usually at a maximum, and 2) very stable environments, when the plume concentration at the forest top is at a maximum and small amounts of turbulent mixing can move a substantial portion of the plume into the forest. Plume interactions with the forest during stable periods are of particular importance because these conditions are usually considered the worst-case scenario for downwind effects from a plume. The pattern of plume mixing into the forest was similar during the year except during summer when the amount of plume mixed into the forest was nearly negligible for all but stable periods. If the model results indicating increased deposition into the forest during stable conditions can be confirmed, it would allow for a reduction in the limitations that restrict facility operations while maintaining conservative estimates for downwind effects. Continuing work is planned to confirm these results as well as estimate specific deposition velocity values for use in toolbox models used in regulatory roles.

  5. Guanidino groups greatly enhance the action of antimicrobial peptidomimetics against bacterial cytoplasmic membranes

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Andreev, Konstantin; Bianchi, Christopher; Laursen, Jonas S.; Citterio, Linda; Hein-Kristensen, Line; Gram, Lone; Kuzmenko, Ivan; Olsen, Christian A.; Gidalevitz, David

    2014-05-28

    In this study, antimicrobial peptides or their synthetic mimics are a promising class of potential new antibiotics. Herein we assess the effect of the type of cationic side chain (i.e., guanidino vs. amino groups) on the membrane perturbing mechanism of antimicrobial ?-peptide?-peptoid chimeras. Langmuir monolayers composed of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylglycerol (DPPG) were used to model cytoplasmic membranes of both Gram-positive and Gram-negative bacteria, while lipopolysaccharide Kdo2-lipid A monolayers were mimicking the outer membrane of Gram-negative species. We report the results of the measurements using an array of techniques, including high-resolution synchrotron surface X-ray scattering, epifluorescence microscopy, and in vitro antimicrobial activity tomorestudy the molecular mechanisms of peptidomimetic interaction with bacterial membranes. We found guanidino group-containing chimeras to exhibit greater disruptive activity on DPPG monolayers than the amino group-containing analogues. However, this effect was not observed for lipopolysaccharide monolayers where the difference was negligible. Furthermore, the addition of the nitrobenzoxadiazole fluorophore did not reduce the insertion activity of these antimicrobials into both model membrane systems examined, which may be useful for future cellular localization studies.less

  6. Relation between combustion heat and chemical wood composition during white and brown rot

    SciTech Connect (OSTI)

    Dobry, J.; Dziurzynski, A.; Rypacek, V.

    1986-01-01

    Samples of beech and spruce wood were incubated with the white rot fungi Pleurotus ostreatus and Lentinus tigrinus and the brown rot fungi Fomitopsis pinicola and Serpula lacrymans (S. lacrimans) for four months. Decomposition (expressed as percent weight loss) and amounts of holocellulose, lignin, humic acids (HU), hymatomelanic acids (HY) and fulvo acids (FU) were determined and expressed in weight percent. Combustion heat of holocellulose and lignin was determined in healthy wood and in specimens where decomposition was greater than 50%. During white rot decomposition, combustion heat was unchanged even at high decomposition and the relative amounts of holocellulose and lignin remained the same. Total amounts of HU, HY and FU increased during the initial stages and stabilized at 20%. The content of HU plus HY was negligible even at the highest degree of decomposition. During brown rot decomposition, combustion heat was unchanged only in the initial stages, it increased continously with increasing rot. Lignin content was unchanged in the initial stages and increased after 30% weight loss. Total amounts of HU, HY and FU increased continuously, reaching higher values than in white rot decomposition; there were differences between the two species. Biosynthesis of HU plus HY began when weight loss reached 30%; there were differences in absolute and relative amounts between species. 24 references.

  7. Opportunities and Challenges for Water and Wastewater Industries to Provide Exchangeable Services

    SciTech Connect (OSTI)

    Sparn, Bethany; Hunsberger, Randolph

    2015-11-13

    Water and wastewater treatment plants and distribution systems use significant amounts of energy, around 2 - 4% of the total electricity used in the US, and their energy use is projected to increase as populations increase and regulations become more stringent. Water and wastewater systems have largely been disconnected from the electric utilities' efforts to improve energy efficiency and provide energy efficiency and provide grid services, likely because their core mission is to provide clean water and treated wastewater. Energy efficiency has slowly crept into the water and wastewater industry as the economic benefit has become more apparent, but there is still potential for significant improvement. Some of the larger, more progressive water utilities are starting to consider providing grid services; however, it remains a foreign concept to many. This report explores intrinsic mechanisms by which the water and wastewater industries can provide exchangeable services, the benefit to the parties involved, and the barriers to implementation. It also highlights relevant case studies and next steps. Although opportunities for increasing process efficiencies are certainly available, this report focuses on the exchangeable services that water and wastewater loads can provide to help maintain grid reliability, keep overall costs down, and increase the penetration of distributed renewables on the electric grid. These services have potential to provide water utilities additional value streams, using existing equipment with modest or negligible upgrade cost.

  8. Simulation of lean NOx trap performance with microkinetic chemistry and without mass transfer.

    SciTech Connect (OSTI)

    Larson, Rich; Daw, C. Stuart; Pihl, Josh A.; Chakravarthy, V. Kalyana

    2011-08-01

    A microkinetic chemical reaction mechanism capable of describing both the storage and regeneration processes in a fully formulated lean NO{sub x} trap (LNT) is presented. The mechanism includes steps occurring on the precious metal, barium oxide (NO{sub x} storage), and cerium oxide (oxygen storage) sites of the catalyst. The complete reaction set is used in conjunction with a transient plug flow reactor code to simulate not only conventional storage/regeneration cycles with a CO/H{sub 2} reductant, but also steady flow temperature sweep experiments that were previously analyzed with just a precious metal mechanism and a steady state code. The results show that NO{sub x} storage is not negligible during some of the temperature ramps, necessitating a re-evaluation of the precious metal kinetic parameters. The parameters for the entire mechanism are inferred by finding the best overall fit to the complete set of experiments. Rigorous thermodynamic consistency is enforced for parallel reaction pathways and with respect to known data for all of the gas phase species involved. It is found that, with a few minor exceptions, all of the basic experimental observations can be reproduced with these purely kinetic simulations, i.e., without including mass-transfer limitations. In addition to accounting for normal cycling behavior, the final mechanism should provide a starting point for the description of further LNT phenomena such as desulfation and the role of alternative reductants.

  9. Formation of PtSi Schottky barrier MOSFETs using plasma etching

    SciTech Connect (OSTI)

    Woo, Young Min; Hwang, Wan Sik; Yoo, Won Jong

    2015-03-15

    PtSi Schottky barrier (SB) MOSFETs were fabricated and their device performance was characterized. PtSi was selected instead of NiSi to form the p-type SB junction since such a configuration would be easy to fabricate through SF{sub 6} based plasma etching. The addition of He-O{sub 2} in SF{sub 6} decreases the etching rate of PtSi while the etching rate of Pt remains unchanged. The retardation in the etching rate of PtSi in He-O{sub 2}/SF{sub 6} is attributed to the formation of a metal oxide on the etched PtSi surface, as evidenced by the x-ray photoelectron spectroscopy results. Optical emission spectroscopy was conducted to establish the endpoint where the wavelength from the feed gas was traced instead of tracing the etching by-products since the by-products have little association with the plasma reaction. The I{sub DS}V{sub DS} curves at various V{sub G}V{sub TH} indicate that plasma etching resulted in the successful removal of the Pt on the sidewall region, with negligible damage to the S/D area.

  10. Calculation of combined diffusion coefficients in SF{sub 6}-Cu mixtures

    SciTech Connect (OSTI)

    Zhong, Linlin; Wang, Xiaohua Rong, Mingzhe Wu, Yi; Murphy, Anthony B.

    2014-10-15

    Diffusion coefficients play an important role in the description of the transport of metal vapours in gas mixtures. This paper is devoted to the calculation of four combined diffusion coefficients, namely, the combined ordinary diffusion coefficient, combined electric field diffusion coefficient, combined temperature diffusion coefficient, and combined pressure diffusion coefficient in SF{sub 6}-Cu mixtures at temperatures up to 30?000?K. These four coefficients describe diffusion due to composition gradients, applied electric fields, temperature gradients, and pressure gradients, respectively. The influence of copper fluoride and sulfide species on the diffusion coefficients is shown to be negligible. The effect of copper proportion and gas pressures on these diffusion coefficients is investigated. It is shown that increasing the proportion of copper generally increases the magnitude of the four diffusion coefficients, except for copper mole fractions of 90% or more. It is further found that increasing the pressure reduces the magnitude of the coefficients, except for the combined temperature diffusion coefficient, and shifts the maximum of all four coefficients towards higher temperatures. The results presented in this paper can be applied to the simulation of high-voltage circuit breaker arcs.

  11. Bulgeless galaxies at intermediate redshift: Sample selection, color properties, and the existence of powerful active galactic nuclei

    SciTech Connect (OSTI)

    Bizzocchi, Luca; Leonardo, Elvira; Grossi, Marco; Afonso, Jos; Fernandes, Cristina; Retr, Joo; Filho, Mercedes E.; Lobo, Catarina; Griffith, Roger L.; Anton, Sonia; Bell, Eric F.; Brinchmann, Jarle; Henriques, Bruno; Messias, Hugo

    2014-02-10

    We present a catalog of bulgeless galaxies, which includes 19,225 objects selected in four of the deepest, largest multi-wavelength data sets availableCOSMOS, AEGIS, GEMS, and GOODSat intermediate redshift (0.4 ? z ? 1.0). The morphological classification was provided by the Advanced Camera for Surveys General Catalog (ACS-GC), which used publicly available data obtained with the ACS instrument on the Hubble Space Telescope. Rest-frame photometric quantities were derived using kcorrect. We analyze the properties of the sample and the evolution of pure-disk systems with redshift. Very massive [log (M {sub *}/M {sub ?}) > 10.5] bulgeless galaxies contribute to ?30% of the total galaxy population number density at z ? 0.7, but their number density drops substantially with decreasing redshift. We show that only a negligible fraction of pure disks appear to be quiescent systems, and red sequence bulgeless galaxies show indications of dust-obscured star formation. X-ray catalogs were used to search for X-ray emission within our sample. After visual inspection and detailed parametric morphological fitting we identify 30 active galactic nuclei (AGNs) that reside in galaxies without a classical bulge. The finding of such peculiar objects at intermediate redshift shows that while AGN growth in merger-free systems is a rare event (0.2% AGN hosts in this sample of bulgeless galaxies), it can indeed happen relatively early in the history of the universe.

  12. Catastrophic photometric redshift errors: Weak-lensing survey requirements

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bernstein, Gary; Huterer, Dragan

    2010-01-11

    We study the sensitivity of weak lensing surveys to the effects of catastrophic redshift errors - cases where the true redshift is misestimated by a significant amount. To compute the biases in cosmological parameters, we adopt an efficient linearized analysis where the redshift errors are directly related to shifts in the weak lensing convergence power spectra. We estimate the number Nspec of unbiased spectroscopic redshifts needed to determine the catastrophic error rate well enough that biases in cosmological parameters are below statistical errors of weak lensing tomography. While the straightforward estimate of Nspec is ~106 we find that using onlymore » the photometric redshifts with z ≤ 2.5 leads to a drastic reduction in Nspec to ~ 30,000 while negligibly increasing statistical errors in dark energy parameters. Therefore, the size of spectroscopic survey needed to control catastrophic errors is similar to that previously deemed necessary to constrain the core of the zs – zp distribution. We also study the efficacy of the recent proposal to measure redshift errors by cross-correlation between the photo-z and spectroscopic samples. We find that this method requires ~ 10% a priori knowledge of the bias and stochasticity of the outlier population, and is also easily confounded by lensing magnification bias. In conclusion, the cross-correlation method is therefore unlikely to supplant the need for a complete spectroscopic redshift survey of the source population.« less

  13. Geoneutrinos and Heat Production in the Earth: Constraints and Implications

    ScienceCinema (OSTI)

    McDonough, Bill [University of Maryland, College Park, Maryland, United States

    2010-01-08

    Recent results from antineutrino (geoneutrino) studies at KamLAND are coincident with geochemical models of Th and U in the Earth.  KamLAND and Borexino detectors are on line, thus uncertainties in counting statistics will be reduced as data are accumulated.  The SNO+ detector, situated in the middle of the North American plate will come on line in ~3 yrs and will be best suited to yield a precise estimate of the continental contribution to the Earth?s Th & U budget.  The distribution of heat producing elements in the Earth drives convection and plate tectonics.  Geochemical models posit that ~40% of the heat producing elements are in the continental crust, with the remainder in the mantle.  Although models of core formation allow for the incorporation of heat producing elements, the core contribution of radiogenic heating is considered to be negligible.  Most parameterized convection models for the Earth require significant amounts of radiogenic heating of the Earth, a factor of two greater than geochemical models predict.  The initial KamLAND results challenge these geophysical models and support geochemical models calling for a significant contribution from secular cooling of the mantle.

  14. Effect of Cl{sub 2}- and HBr-based inductively coupled plasma etching on InP surface composition analyzed using in situ x-ray photoelectron spectroscopy

    SciTech Connect (OSTI)

    Bouchoule, S.; Vallier, L.; Patriarche, G.; Chevolleau, T.; Cardinaud, C.

    2012-05-15

    A Cl{sub 2}-HBr-O{sub 2}/Ar inductively coupled plasma (ICP) etching process has been adapted for the processing of InP-based heterostructures in a 300-mm diameter CMOS etching tool. Smooth and anisotropic InP etching is obtained at moderate etch rate ({approx}600 nm/min). Ex situ x-ray energy dispersive analysis of the etched sidewalls shows that the etching anisotropy is obtained through a SiO{sub x} passivation mechanism. The stoichiometry of the etched surface is analyzed in situ using angle-resolved x-ray photoelectron spectroscopy. It is observed that Cl{sub 2}-based ICP etching results in a significantly P-rich surface. The phosphorous layer identified on the top surface is estimated to be {approx}1-1.3-nm thick. On the other hand InP etching in HBr/Ar plasma results in a more stoichiometric surface. In contrast to the etched sidewalls, the etched surface is free from oxides with negligible traces of silicon. Exposure to ambient air of the samples submitted to Cl{sub 2}-based chemistry results in the complete oxidation of the P-rich top layer. It is concluded that a post-etch treatment or a pure HBr plasma step may be necessary after Cl{sub 2}-based ICP etching for the recovery of the InP material.

  15. Environmental assessment for the proposed CMR Building upgrades at the Los Alamos National Laboratory, Los Alamos, New Mexico. Final document

    SciTech Connect (OSTI)

    NONE

    1997-02-04

    In order to maintain its ability to continue to conduct uninterrupted radioactive and metallurgical research in a safe, secure, and environmentally sound manner, the US Department of Energy (DOE) proposes to upgrade the Los Alamos National Laboratory (LANL) Chemistry and Metallurgy Research (CMR) Building. The building was built in the early 1950s to provide a research and experimental facility for analytical chemistry, plutonium and uranium chemistry, and metallurgy. Today, research and development activities are performed involving nuclear materials. A variety of radioactive and chemical hazards are present. The CMR Building is nearing the end of its original design life and does not meet many of today`s design codes and standards. The Proposed Action for this Environmental Assessment (EA) includes structural modifications to some portions of the CMR Building which do not meet current seismic criteria for a Hazard Category 2 Facility. Also included are upgrades and improvements in building ventilation, communications, monitoring, and fire protection systems. This EA analyzes the environmental effects of construction of the proposed upgrades. The Proposed Action will have no adverse effects upon agricultural and cultural resources, wetlands and floodplains, endangered and threatened species, recreational resources, or water resources. The Proposed Action would have negligible effects on human health and transportation, and would not pose a disproportionate adverse health or environmental impact on minority or low-income populations within an 80 kilometer (50 mile) radius of the CMR Building.

  16. Enhanced reaction rates in NDP analysis with neutron scattering

    SciTech Connect (OSTI)

    Downing, R. Gregory

    2014-04-15

    Neutron depth profiling (NDP) makes accessible quantitative information on a few isotopic concentration profiles ranging from the surface into the sample a few micrometers. Because the candidate analytes for NDP are few, there is little interference encountered. Furthermore, neutrons have no charge so mixed chemical states in the sample are of no direct concern. There are a few nuclides that exhibit large probabilities for neutron scattering. The effect of neutron scattering on NDP measurements has not previously been evaluated as a basis for either enhancing the reaction rates or as a source of measurement error. Hydrogen is a common element exhibiting large neutron scattering probability found in or around sample volumes being analyzed by NDP. A systematic study was conducted to determine the degree of signal change when neutron scattering occurs during analysis. The relative signal perturbation was evaluated for materials of varied neutron scattering probability, concentration, total mass, and geometry. Signal enhancements up to 50% are observed when the hydrogen density is high and in close proximity to the region of analysis with neutron beams of sub thermal energies. Greater signal enhancements for the same neutron number density are reported for thermal neutron beams. Even adhesive tape used to position the sample produces a measureable signal enhancement. Because of the shallow volume, negligible distortion of the NDP measured profile shape is encountered from neutron scattering.

  17. Loss of spent fuel pool cooling PRA: Model and results

    SciTech Connect (OSTI)

    Siu, N.; Khericha, S.; Conroy, S.; Beck, S.; Blackman, H.

    1996-09-01

    This letter report documents models for quantifying the likelihood of loss of spent fuel pool cooling; models for identifying post-boiling scenarios that lead to core damage; qualitative and quantitative results generated for a selected plant that account for plant design and operational practices; a comparison of these results and those generated from earlier studies; and a review of available data on spent fuel pool accidents. The results of this study show that for a representative two-unit boiling water reactor, the annual probability of spent fuel pool boiling is 5 {times} 10{sup {minus}5} and the annual probability of flooding associated with loss of spent fuel pool cooling scenarios is 1 {times} 10{sup {minus}3}. Qualitative arguments are provided to show that the likelihood of core damage due to spent fuel pool boiling accidents is low for most US commercial nuclear power plants. It is also shown that, depending on the design characteristics of a given plant, the likelihood of either: (a) core damage due to spent fuel pool-associated flooding, or (b) spent fuel damage due to pool dryout, may not be negligible.

  18. Estimates of mercury flux into the United States from non-local and global sources : results from a 3-D CTM simulation.

    SciTech Connect (OSTI)

    Drewniak, B. A.; Kotamarthi, V. R.; Streets, D.; Kim, M.; Crist, K.; Ohio Univ.

    2008-11-01

    The sensitivity of Hg concentration and deposition in the United States to emissions in China was investigated by using a global chemical transport model: Model for Ozone and Related Chemical Tracers (MOZART). Two forms of gaseous Hg were included in the model: elemental Hg (HG(0)) and oxidized or reactive Hg (HGO). We simulated three different emission scenarios to evaluate the model's sensitivity. One scenario included no emissions from China, while the others were based on different estimates of Hg emissions in China. The results indicated, in general, that when Hg emissions were included, HG(0) concentrations increased both locally and globally. Increases in Hg concentrations in the United States were greatest during spring and summer, by as much as 7%. Ratios of calculated concentrations of Hg and CO near the source region in eastern Asia agreed well with ratios based on measurements. Increases similar to those observed for HG(0) were also calculated for deposition of HGO. Calculated increases in wet and dry deposition in the United States were 5-7% and 5-9%, respectively. The results indicate that long-range transcontinental transport of Hg has a non-negligible impact on Hg deposition levels in the United States.

  19. On the nature of the deactivation of supported palladium nanoparticle catalysts in the decarboxylation of fatty acids.

    SciTech Connect (OSTI)

    Ping, E. W.; Pierson, J.; Wallace, R.; Miller, J. T.; Fuller, T. F.; Jones, C. W.

    2011-04-15

    Supported palladium catalysts are effective catalysts for the hydrogen-free decarboxylation of fatty acids. However, the catalysts deactivate severely after one use. Here, the recyclability of a well-defined, mesoporous silica-supported palladium nanoparticle catalyst is evaluated in the batch decarboxylation of stearic acid at 300 C under inert atmosphere, producing n-heptadecane. The nature of the catalyst deactivation is examined in detail via an array of characterization techniques. X-ray photoelectron spectroscopy (XPS) demonstrates that little palladium surface oxidation occurs over the course of the reaction, and a combination of X-ray absorption spectroscopy and transmission electron microscopy (TEM) suggests negligible particle sintering or agglomeration. Physisorption and chemisorption measurements demonstrate substantial loss in total surface area and porosity as well as accessible palladium surface area with these losses attributed to significant organic deposition on the catalyst, as verified via thermogravimetric analysis. High temperature calcination is applied to combust and remove these residues, but resultant nanoparticle agglomeration is significant. Solid state nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FT-IR) and solid dissolution followed by organic extraction methodologies demonstrate that the carbonaceous deposits are not coke but rather strongly adsorbed reactants and products. Detrimental coke formation, as suggested by prior literature, is verified to be absent, as extraction of the surface-deposited organic species yields nearly complete recovery of the total surface area, pore volume, and active palladium surface area. Furthermore, the regenerated catalyst exhibits a corresponding significant recovery of decarboxylation activity.

  20. Radiation source

    DOE Patents [OSTI]

    Thode, Lester E. (Los Alamos, NM)

    1981-01-01

    A device and method for relativistic electron beam heating of a high-density plasma in a small localized region. A relativistic electron beam generator or accelerator produces a high-voltage electron beam which propagates along a vacuum drift tube and is modulated to initiate electron bunching within the beam. The beam is then directed through a low-density gas chamber which provides isolation between the vacuum modulator and the relativistic electron beam target. The relativistic beam is then applied to a high-density target plasma which typically comprises DT, DD, or similar thermonuclear gas at a density of 10.sup.17 to 10.sup.20 electrons per cubic centimeter. The target gas is ionized prior to application of the relativistic electron beam by means of a laser or other preionization source to form a plasma. Utilizing a relativistic electron beam with an individual particle energy exceeding 3 MeV, classical scattering by relativistic electrons passing through isolation foils is negligible. As a result, relativistic streaming instabilities are initiated within the high-density target plasma causing the relativistic electron beam to efficiently deposit its energy into a small localized region of the high-density plasma target.

  1. Effect of Phosphate, Fluoride, and Nitrate on Gibbsite Dissolution Rate and Solubility

    SciTech Connect (OSTI)

    Herting, Daniel L.

    2014-01-29

    Laboratory tests have been completed with simulated tank waste samples to investigate the effects of phosphate, fluoride, and nitrate on the dissolution rate and equilibrium solubility of gibbsite in sodium hydroxide solution at 22 and 40{degrees}C. Results are compared to relevant literature data and to computer model predictions. The presence of sodium nitrate (3 M) caused a reduction in the rate of gibbsite dissolution in NaOH, but a modest increase in the equilibrium solubility of aluminum. The increase in solubility was not as large, though, as the increase predicted by the computer model. The presence of phosphate, either as sodium phosphate or sodium fluoride phosphate, had a negligible effect on the rate of gibbsite dissolution, but caused a slight increase in aluminum solubility. The magnitude of the increased solubility, relative to the increase caused by sodium nitrate, suggests that the increase is due to ionic strength (or water activity) effects, rather than being associated with the specific ion involved. The computer model predicted that phosphate would cause a slight decrease in aluminum solubility, suggesting some Al-PO4 interaction. No evidence was found of such an interaction.

  2. Numerical simulation of plasma heating of a composite powder particle

    SciTech Connect (OSTI)

    Demetriou, M.D.; Lavine, A.S.; Ghoniem, N.M.

    1999-07-01

    The use of fine composite powder particles (composed of a ceramic core and a metallic coating) in plasma spraying processes is desirable in developing thin film coatings that possess high abrasion as well as high fracture resistance. Quantitative knowledge of the thermal behavior of a composite particle in a plasma beam is essential in optimizing the process variables to achieve uniform melting of the coating material. In this work, a numerical model is developed to analyze the in-flight thermal behavior of a spherically symmetric WC-Co composite particle travelling in an argon arc-jet DC plasma under strongly unsteady plasma conditions. The model gives quantitative as well as qualitative information about the thermal response of the heated particle. The important features that are addressed are the temperature response of the particle; the history of the location of the melting and vaporization fronts; and the physical state of the particle at the end of its flight. For the conditions investigated, it was determined that the internal conduction resistance is negligible as compared to the net external resistance. However, the presence of the ceramic base was found to affect the transient heating process since its content in the particle composition determines the time constant of the process. Another interesting observation is that proper selection of the particle injection speed and injection location can be effective means for optimizing the heating process and achieving uniform melting of the coating material.

  3. Oxygen transport in off-stoichiometric uranium dioxide mediated by defect clustering dynamics

    SciTech Connect (OSTI)

    Yu, Jianguo Bai, Xian-Ming; El-Azab, Anter; Allen, Todd R.

    2015-03-07

    Oxygen transport is central to many properties of oxides such as stoichiometric changes, phase transformation, and ionic conductivity. In this paper, we report a mechanism for oxygen transport in uranium dioxide (UO{sub 2}) in which the kinetics is mediated by defect clustering dynamics. In particular, the kinetic Monte Carlo method has been used to investigate the kinetics of oxygen transport in UO{sub 2} under the condition of creation and annihilation of oxygen vacancies and interstitials as well as oxygen interstitial clustering, with variable off-stoichiometry and temperature conditions. It is found that in hypo-stoichiometric UO{sub 2?x}, oxygen transport is well described by the vacancy diffusion mechanism while in hyper-stoichiometric UO{sub 2+x}, oxygen interstitial cluster diffusion contributes significantly to oxygen transport kinetics, particularly at high temperatures and high off-stoichiometry levels. It is also found that di-interstitial clusters and single interstitials play dominant roles in oxygen diffusion while other larger clusters have negligible contributions. However, the formation, coalescence, and dissociation of these larger clusters indirectly affects the overall oxygen diffusion due to their interactions with mono and di-interstitials, thus providing an explanation of the experimental observation of saturation or even drop of oxygen diffusivity at high off-stoichiometry.

  4. High-resolution single-shot spectral monitoring of hard x-ray free-electron laser radiation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Makita, M.; Karvinen, P.; Zhu, D.; Juranic, P. N.; Grünert, J.; Cartier, S.; Jungmann-Smith, J. H.; Lemke, H. T.; Mozzanica, A.; Nelson, S.; et al

    2015-10-16

    We have developed an on-line spectrometer for hard x-ray free-electron laser (XFEL) radiation based on a nanostructured diamond diffraction grating and a bent crystal analyzer. Our method provides high spectral resolution, interferes negligibly with the XFEL beam, and can withstand the intense hard x-ray pulses at high repetition rates of >100 Hz. The spectrometer is capable of providing shot-to-shot spectral information for the normalization of data obtained in scientific experiments and optimization of the accelerator operation parameters. We have demonstrated these capabilities of the setup at the Linac Coherent Light Source, in self-amplified spontaneous emission mode at full energy ofmore » >1 mJ with a 120 Hz repetition rate, obtaining a resolving power of Ε/δΕ > 3 × 104. In conclusion, the device was also used to monitor the effects of pulse duration down to 8 fs by analysis of the spectral spike width.« less

  5. Suppression of metastable-phase inclusion in N-polar (0001{sup }) InGaN/GaN multiple quantum wells grown by metalorganic vapor phase epitaxy

    SciTech Connect (OSTI)

    Shojiki, Kanako Iwabuchi, Takuya; Kuboya, Shigeyuki; Choi, Jung-Hun; Tanikawa, Tomoyuki; Hanada, Takashi; Katayama, Ryuji; Matsuoka, Takashi; Usami, Noritaka

    2015-06-01

    The metastable zincblende (ZB) phase in N-polar (0001{sup }) (?c-plane) InGaN/GaN multiple quantum wells (MQWs) grown by metalorganic vapor phase epitaxy is elucidated by the electron backscatter diffraction measurements. From the comparison between the ?c-plane and Ga-polar (0001) (+c-plane), the ?c-plane MQWs were found to be suffered from the severe ZB-phase inclusion, while ZB-inclusion is negligible in the +c-plane MQWs grown under the same growth conditions. The ZB-phase inclusion is a hurdle for fabricating the ?c-plane light-emitting diodes because the islands with a triangular shape appeared on a surface in the ZB-phase domains. To improve the purity of stable wurtzite (WZ)-phase, the optimum conditions were investigated. The ZB-phase is dramatically eliminated with decreasing the V/III ratio and increasing the growth temperature. To obtain much-higher-quality MQWs, the thinner InGaN wells and the hydrogen introduction during GaN barriers growth were tried. Consequently, MQWs with almost pure WZ phase and with atomically smooth surface have been demonstrated.

  6. Electronic structure of the heavy-fermion caged compound Ce3Pd20X6(X=Si,Ge) studied by density functional theory and photoelectron spectroscopy

    SciTech Connect (OSTI)

    Yamaoka, Hitoshi; Schwier, Eike F.; Arita, Masashi; Shimada, Kenya; Tsujii, Naohito; Jarrige, Ignace; Jiang, Jian; Hayashi, Hirokazu; Iwasawa, Hideaki; Namatame, Hirofumi; Taniguchi, Masaki; Kitazawa, Hideaki

    2015-03-30

    The electronic structure of Ce₃Pd₂₀X₆ (X = Si, Ge) has been studied using detailed density functional theory (DFT) calculations and high-resolution photoelectron spectroscopy (PES) measurements. The orbital decomposition of the electronic structure by DFT calculations indicates that Ce atoms at the (8c) site surrounded by 16 Pd atoms have a more localized nature and a tendency to be magnetic. Ce atoms in the (4a) site surrounded by 12 Pd and 6 X atoms, on the other, show only a negligible magnetic moment. In the photoemission valence-band spectra we observe a strong f⁰ (Ce⁴⁺) component with a small fraction of f¹ (Ce³⁺) component. The spectral weight of f¹ component near the Fermi level Ce₃Pd₂₀Si₆ is stronger than that for Ce₃Pd₂₀Ge₆ at the 4d-4f resonance, suggesting stronger c-f hybridization in the former. This may hint to the origin of the large electronic specific coefficient of Ce₃Pd₂₀Si₆ compared to Ce₃Pd₂₀Ge₆.

  7. Observation of finite-wavelength screening in high-energy-density matter

    SciTech Connect (OSTI)

    Chapman, D. A.; Vorberger, J.; Fletcher, L. B.; Baggott, R. A.; Divol, L.; Döppner, T.; Falcone, R. W.; Glenzer, S. H.; Gregori, G.; Guymer, T. M.; Kritcher, A. L.; Landen, O. L.; Ma, T.; Pak, A. E.; Gericke, D. O.

    2015-04-23

    A key component for the description of charged particle systems is the screening of the Coulomb interaction between charge carriers. First investigated in the 1920s by Debye and Hückel for electrolytes, charge screening is important for determining the structural and transport properties of matter as diverse as astrophysical and laboratory plasmas, nuclear matter such as quark-gluon plasmas, electrons in solids, planetary cores and charged macromolecules. For systems with negligible dynamics, screening is still mostly described using a Debye–Hückel-type approach. Here, we report the novel observation of a significant departure from the Debye–Hückel-type model in high-energy-density matter by probing laser-driven, shock-compressed plastic with high-energy X-rays. We use spectrally resolved X-ray scattering in a geometry that enables direct investigation of the screening cloud, and demonstrate that the observed elastic scattering amplitude is only well described within a more general approach.

  8. CALIBRATING STELLAR VELOCITY DISPERSIONS BASED ON SPATIALLY RESOLVED H-BAND SPECTRA FOR IMPROVING THE M{sub BH}-{sigma}{sub *} RELATION

    SciTech Connect (OSTI)

    Kang, Wol-Rang; Woo, Jong-Hak; Park, Daeseong; Schulze, Andreas; Riechers, Dominik A.; Kim, Sang Chul; Smolcic, Vernesa

    2013-04-10

    To calibrate stellar velocity dispersion measurements from optical and near-IR stellar lines, and to improve the black hole mass (M{sub BH})-stellar velocity dispersion ({sigma}{sub *}) relation, we measure {sigma}{sub *} based on high-quality H-band spectra for a sample of 31 nearby galaxies, for which dynamical M{sub BH} is available in the literature. By comparing velocity dispersions measured from stellar lines in the H-band with those measured from optical stellar lines, we find no significant difference, suggesting that optical and near-IR stellar lines represent the same kinematics and that dust effect is negligible for early-type galaxies. Based on the spatially resolved rotation and velocity dispersion measurements along the major axis of each galaxy, we find that a rotating stellar disk is present for 80% of galaxies in the sample. For galaxies with a rotation component, {sigma}{sub *} measured from a single aperture spectrum can vary by up to {approx}20%, depending on the size of the adopted extraction aperture. To correct for the rotational broadening, we derive luminosity-weighted {sigma}{sub *} within the effective radius of each galaxy, providing uniformly measured velocity dispersions to improve the M{sub BH}-{sigma}{sub *} relation.

  9. Flexible Pillared Graphene-Paper Electrodes for High-Performance Electrochemical Supercapacitors

    SciTech Connect (OSTI)

    Wang, Gongkai; Sun, Xiang; Lu, Fengyuan; Sun, Hongtao; Yu, Mingpeng; Jiang, Weilin; Liu, Changsheng; Lian, Jie

    2012-02-09

    Flexible graphene paper (GP) pillared by carbon black (CB) nanoparticles using a simple vacuum filtration method is developed as a high-performance electrode material for supercapacitors. Through the introduction of CB nanoparticles as spacers, the self-restacking of graphene sheets during the filtration process is mitigated to a great extent. The pillared GP-based supercapacitors exhibit excellent electrochemical performances and cyclic stabilities compared with GP without the addition of CB nanoparticles. At a scan rate of 10 mV s?1, the specific capacitance of the pillared GP is 138 F g^?1 and 83.2 F g^?1 with negligible 3.85% and 4.35% capacitance degradation after 2000 cycles in aqueous and organic electrolytes, respectively. At an extremely fast scan rate of 500 mV s ^?1, the specific capacitance can reach 80 F g^?1 in aqueous electrolyte. No binder is needed for assembling the supercapacitor cells and the pillared GP itself may serve as a current collector due to its intrinsic high electrical conductivity. The pillared GP has great potential in the development of promising flexible and ultralight-weight supercapacitors for electrochemical energy storage.

  10. Modeling particle loss in ventilation ducts

    SciTech Connect (OSTI)

    Sippola, Mark R.; Nazaroff, William W.

    2003-04-01

    Empirical equations were developed and applied to predict losses of 0.01-100 {micro}m airborne particles making a single pass through 120 different ventilation duct runs typical of those found in mid-sized office buildings. For all duct runs, losses were negligible for submicron particles and nearly complete for particles larger than 50 {micro}m. The 50th percentile cut-point diameters were 15 {micro}m in supply runs and 25 {micro}m in return runs. Losses in supply duct runs were higher than in return duct runs, mostly because internal insulation was present in portions of supply duct runs, but absent from return duct runs. Single-pass equations for particle loss in duct runs were combined with models for predicting ventilation system filtration efficiency and particle deposition to indoor surfaces to evaluate the fates of particles of indoor and outdoor origin in an archetypal mechanically ventilated building. Results suggest that duct losses are a minor influence for determining indoor concentrations for most particle sizes. Losses in ducts were of a comparable magnitude to indoor surface losses for most particle sizes. For outdoor air drawn into an unfiltered ventilation system, most particles smaller than 1 {micro}m are exhausted from the building. Large particles deposit within the building, mostly in supply ducts or on indoor surfaces. When filters are present, most particles are either filtered or exhausted. The fates of particles generated indoors follow similar trends as outdoor particles drawn into the building.

  11. Short-circuit current density imaging of crystalline silicon solar cells via lock-in thermography: Robustness and simplifications

    SciTech Connect (OSTI)

    Fertig, Fabian Greulich, Johannes; Rein, Stefan

    2014-11-14

    Spatially resolved determination of solar cell parameters is beneficial for loss analysis and optimization of conversion efficiency. One key parameter that has been challenging to access by an imaging technique on solar cell level is short-circuit current density. This work discusses the robustness of a recently suggested approach to determine short-circuit current density spatially resolved based on a series of lock-in thermography images and options for a simplified image acquisition procedure. For an accurate result, one or two emissivity-corrected illuminated lock-in thermography images and one dark lock-in thermography image have to be recorded. The dark lock-in thermography image can be omitted if local shunts are negligible. Furthermore, it is shown that omitting the correction of lock-in thermography images for local emissivity variations only leads to minor distortions for standard silicon solar cells. Hence, adequate acquisition of one image only is sufficient to generate a meaningful map of short-circuit current density. Beyond that, this work illustrates the underlying physics of the recently proposed method and demonstrates its robustness concerning varying excitation conditions and locally increased series resistance. Experimentally gained short-circuit current density images are validated for monochromatic illumination in comparison to the reference method of light-beam induced current.

  12. Global Distribution and Climate Forcing of Marine Organic Aerosol - Part 2: Effects on Cloud Properties and Radiative Forcing

    SciTech Connect (OSTI)

    Gantt, Brett; Xu, Jun; Meskhidze, N.; Zhang, Yang; Nenes, Athanasios; Ghan, Steven J.; Liu, Xiaohong; Easter, Richard C.; Zaveri, Rahul A.

    2012-07-25

    A series of simulations with the Community Atmosphere Model version 5 (CAM5) with a 7-mode Modal Aerosol Model were conducted to assess the changes in cloud microphysical properties and radiative forcing resulting from marine organic aerosols. Model simulations show that the anthropogenic aerosol indirect forcing (AIF) predicted by CAM5 is decreased in absolute magnitude by up to 0.09 Wm{sup -2} (7 %) when marine organic aerosols are included. Changes in the AIF from marine organic aerosols are associated with small global increases in low-level incloud droplet number concentration and liquid water path of 1.3 cm{sup -3} (1.5 %) and 0.22 gm{sup -2} (0.5 %), respectively. Areas especially sensitive to changes in cloud properties due to marine organic aerosol include the Southern Ocean, North Pacific Ocean, and North Atlantic Ocean, all of which are characterized by high marine organic emission rates. As climate models are particularly sensitive to the background aerosol concentration, this small but non-negligible change in the AIF due to marine organic aerosols provides a notable link for ocean-ecosystem marine low-level cloud interactions and may be a candidate for consideration in future earth system models.

  13. Construction and operation of the Howard T. Ricketts Laboratory.

    SciTech Connect (OSTI)

    Van Lonkhuyzen, R.; Stull, L.; Butler, J.; Chang, Y.; Allison, T.; O'Rourke, D.

    2006-01-01

    The National Institutes of Health (NIH) has proposed to partially fund the construction of the Howard T. Ricketts (HTR) regional biocontainment laboratory (RBL) by the University of Chicago at the U.S. Department of Energy's (DOE's) Argonne National Laboratory in Argonne, Illinois. The HTR Laboratory (HTRL) would be constructed, owned, and operated by the University of Chicago on land leased to it by DOE. The preferred project site is located north of Eastwood Drive and west of Outer Circle Road and is near the biological sciences building. This environmental assessment addresses the potential environmental effects resulting from construction and operation of the proposed facility. The proposed project involves the construction of a research facility with a footprint up to approximately 44,000 ft{sup 2} (4,088 m{sup 2}). The proposed building would house research laboratories, including Biosafety Level 2 and 3 biocontainment space, animal research facilities, administrative offices, and building support areas. The NIH has identified a need for new facilities to support research on potential bioterrorism agents and emerging and re-emerging infectious diseases, to protect the nation from such threats to public health. This research requires specialized laboratory facilities that are designed, managed, and operated to protect laboratory workers and the surrounding community from accidental exposure to agents. The proposed HTRL would provide needed biocontainment space to researchers and promote the advancement of knowledge in the disciplines of biodefense and emerging and re-emerging infectious diseases. Several alternatives were considered for the location of the proposed facility, as well as a no action alternative. The preferred alternative includes the construction of a research facility, up to 44,000 ft{sup 2} (4,088 m{sup 2}), at Argonne National Laboratory, a secure government location. Potential impacts to natural and cultural resources have been evaluated in this document. The proposed activities would result in the conversion of approximately 4 acres (2 ha) of old field and open woodland for the proposed facility and landscaped areas. Impacts of the proposed project on the following resources would be minor or negligible: human health, socioeconomics, air quality, noise levels, water quality, waste management, land use, the visual environment, cultural resources, soils, terrestrial biota, wetlands or aquatic biota, threatened and endangered species, transportation, utilities and services, and environmental justice. This environmental assessment has been completed to satisfy the requirements of the National Environmental Policy Act of 1969 and has been prepared in accordance with NIH guidelines and in coordination with federal, state, and local agency requirements. On the basis of the results of this assessment, impacts to environmental resources from the proposed project would be minor or negligible, provided that the project is implemented in accordance with the impact avoidance and mitigation measures described herein.

  14. Dielectric properties of Ba{sub 3-x}K{sub x}CaNb{sub 2}O{sub 9-{delta}} (0.5 < x < 1.25) (KBCN) double perovskites

    SciTech Connect (OSTI)

    Bhella, Surinderjit Singh; Thangadurai, Venkataraman

    2011-05-15

    Graphical abstract: Electrical conductivity, dielectric constant and dielectric loss of Ba{sub 1.75}K{sub 1.25}CaNb{sub 2}O{sub 9-{delta}} in air at 400-700 {sup o}C. Research highlights: {yields} We show the effectiveness of AC impedance spectroscopy to screen dielectric materials and to understand contributing effects on the dielectric properties of polycrystalline metal oxides. {yields} Unlike Ba{sub 3}CaNb{sub 2}O{sub 9}, Ba{sub 3-x}K{sub x}CaNb{sub 2}O{sub 9-{delta}} exhibits negligible grain-boundary and electrode effects to the total electrical properties and is consistent with perovskite-type K-doped BaZrO{sub 3}. {yields} Among the samples investigated, Ba{sub 1.75}K{sub 1.25}CaNb{sub 2}O{sub 9-{delta}} sintered at 1100 {sup o}C showed the highest dielectric constant of 65 at 10{sup 6} Hz and dielectric loss of 0.14 at 400 {sup o}C in air. -- Abstract: We report synthesis, structure and dielectric properties of double perovskite-type Ba{sub 3-x}K{sub x}CaNb{sub 2}O{sub 9-{delta}} (x = 0.5, 0.75, 1, 1.25) (KBCN). Powder X-ray diffraction (XRD) confirmed the formation of double perovskite-type structure and lattice constant decreases with increasing K in KBCN. AC impedance study showed a single semicircle over the investigated temperatures and frequencies in dry H{sub 2}, H{sub 2} + 3% H{sub 2}O, 3% H{sub 2}O + N{sub 2}, while two semicircles were observed at low temperatures in air, which could be attributed to bulk and grain-boundary contributions. Unlike un-doped BCN, KBCN exhibits negligible grain-boundary and electrode effects to the total electrical properties and is consistent with perovskite-type K-doped BaZrO{sub 3}. The bulk dielectric constant and dielectric loss were found to increase with increasing K content in KBCN and also found to change with sintering temperature. Among the samples investigated, Ba{sub 1.75}K{sub 1.25}CaNb{sub 2}O{sub 9-{delta}} sintered at 1100 {sup o}C showed the highest dielectric constant of 65 at 10{sup 6} Hz and dielectric loss of 0.14 at 400 {sup o}C in air. Isothermal dielectric constant and electrical conductivity at 1 MHz were found to be independent at elevated temperatures, while vary at low-frequency and low temperatures. Below 700 {sup o}C, dielectric constant and dielectric loss decreases with increasing frequency, whereas an opposite trend was observed for the electrical conductivity.

  15. Optimization of leaf margins for lung stereotactic body radiotherapy using a flattening filter-free beam

    SciTech Connect (OSTI)

    Wakai, Nobuhide; Sumida, Iori; Otani, Yuki; Suzuki, Osamu; Seo, Yuji; Isohashi, Fumiaki; Yoshioka, Yasuo; Ogawa, Kazuhiko; Hasegawa, Masatoshi

    2015-05-15

    Purpose: The authors sought to determine the optimal collimator leaf margins which minimize normal tissue dose while achieving high conformity and to evaluate differences between the use of a flattening filter-free (FFF) beam and a flattening-filtered (FF) beam. Methods: Sixteen lung cancer patients scheduled for stereotactic body radiotherapy underwent treatment planning for a 7 MV FFF and a 6 MV FF beams to the planning target volume (PTV) with a range of leaf margins (?3 to 3 mm). Forty grays per four fractions were prescribed as a PTV D95. For PTV, the heterogeneity index (HI), conformity index, modified gradient index (GI), defined as the 50% isodose volume divided by target volume, maximum dose (Dmax), and mean dose (Dmean) were calculated. Mean lung dose (MLD), V20 Gy, and V5 Gy for the lung (defined as the volumes of lung receiving at least 20 and 5 Gy), mean heart dose, and Dmax to the spinal cord were measured as doses to organs at risk (OARs). Paired t-tests were used for statistical analysis. Results: HI was inversely related to changes in leaf margin. Conformity index and modified GI initially decreased as leaf margin width increased. After reaching a minimum, the two values then increased as leaf margin increased (V shape). The optimal leaf margins for conformity index and modified GI were ?1.1 0.3 mm (mean 1 SD) and ?0.2 0.9 mm, respectively, for 7 MV FFF compared to ?1.0 0.4 and ?0.3 0.9 mm, respectively, for 6 MV FF. Dmax and Dmean for 7 MV FFF were higher than those for 6 MV FF by 3.6% and 1.7%, respectively. There was a positive correlation between the ratios of HI, Dmax, and Dmean for 7 MV FFF to those for 6 MV FF and PTV size (R = 0.767, 0.809, and 0.643, respectively). The differences in MLD, V20 Gy, and V5 Gy for lung between FFF and FF beams were negligible. The optimal leaf margins for MLD, V20 Gy, and V5 Gy for lung were ?0.9 0.6, ?1.1 0.8, and ?2.1 1.2 mm, respectively, for 7 MV FFF compared to ?0.9 0.6, ?1.1 0.8, and ?2.2 1.3 mm, respectively, for 6 MV FF. With the heart inside the radiation field, the mean heart dose showed a V-shaped relationship with leaf margins. The optimal leaf margins were ?1.0 0.6 mm for both beams. Dmax to the spinal cord showed no clear trend for changes in leaf margin. Conclusions: The differences in doses to OARs between FFF and FF beams were negligible. Conformity index, modified GI, MLD, lung V20 Gy, lung V5 Gy, and mean heart dose showed a V-shaped relationship with leaf margins. There were no significant differences in optimal leaf margins to minimize these parameters between both FFF and FF beams. The authors results suggest that a leaf margin of ?1 mm achieves high conformity and minimizes doses to OARs for both FFF and FF beams.

  16. A COOL DUST FACTORY IN THE CRAB NEBULA: A HERSCHEL STUDY OF THE FILAMENTS

    SciTech Connect (OSTI)

    Gomez, H. L.; Clark, C. J. R.; Gomez, E. L.; Gear, W. K. [School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA (United Kingdom); Krause, O.; Besel, M.-A.; Bouwman, J.; Henning, Th. [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Barlow, M. J.; Swinyard, B. M.; Owen, P. J.; Matsuura, M. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Rho, J. [SOFIA Science Center, Universities Space Research Association, NASA Ames Research Center, MS 232, Moffett Field, CA 94035 (United States); Ivison, R. J.; Sibthorpe, B. [UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Polehampton, E. T. [Space Science and Technology Department, Rutherford Appleton Laboratory, Oxfordshire, OX11 0QX (United Kingdom)

    2012-11-20

    Whether supernovae are major sources of dust in galaxies is a long-standing debate. We present infrared and submillimeter photometry and spectroscopy from the Herschel Space Observatory of the Crab Nebula between 51 and 670 {mu}m as part of the Mass Loss from Evolved StarS program. We compare the emission detected with Herschel with multiwavelength data including millimeter, radio, mid-infrared, and archive optical images. We carefully remove the synchrotron component using the Herschel and Planck fluxes measured in the same epoch. The contribution from line emission is removed using Herschel spectroscopy combined with Infrared Space Observatory archive data. Several forbidden lines of carbon, oxygen, and nitrogen are detected where multiple velocity components are resolved, deduced to be from the nitrogen-depleted, carbon-rich ejecta. No spectral lines are detected in the SPIRE wavebands; in the PACS bands, the line contribution is 5% and 10% at 70 and 100 {mu}m and negligible at 160 {mu}m. After subtracting the synchrotron and line emission, the remaining far-infrared continuum can be fit with two dust components. Assuming standard interstellar silicates, the mass of the cooler component is 0.24{sup +0.32} {sub -0.08} M {sub Sun} for T = 28.1{sup +5.5} {sub -3.2} K. Amorphous carbon grains require 0.11 {+-} 0.01 M {sub Sun} of dust with T = 33.8{sup +2.3} {sub -1.8} K. A single temperature modified blackbody with 0.14 M {sub Sun} and 0.08 M {sub Sun} for silicate and carbon dust, respectively, provides an adequate fit to the far-infrared region of the spectral energy distribution but is a poor fit at 24-500 {mu}m. The Crab Nebula has condensed most of the relevant refractory elements into dust, suggesting the formation of dust in core-collapse supernova ejecta is efficient.

  17. Energy and global warming impacts of HFC refrigerants and emerging technologies: TEWI-III

    SciTech Connect (OSTI)

    Sand, J.R.; Fischer, S.K.; Baxter, V.D.

    1997-06-01

    The use of hydrofluorocarbons (BFCs) which were developed as alternative refrigerants and insulating foam blowing agents to replace chlorofluorocarbons (CFCs) is now being affected by scientific investigations of greenhouse warming and questions about the effects of refrigerants and blowing agents on global warming. A Total Equivalent Warming Impact (TEWI) assessment analyzes the environmental affects of these halogenated working fluids in energy consuming applications by combining a direct effect resulting from the inadvertent release of HFCs to the atmosphere with an indirect effect resulting from the combustion of fossil fuels needed to provide the energy to operate equipment using these compounds as working fluids. TEWI is a more balanced measure of environmental impact because it is not based solely on the global warming potential (GWP) of the working fluid. It also shows the environmental benefit of efficient technologies that result in less CO{sub 2} generation and eventual emission to the earth`s atmosphere. The goal of TEWI is to assess total global warming impact of all the gases released to the atmosphere, including CO{sub 2} emissions from energy conversion. Alternative chemicals and technologies have been proposed as substitutes for HFCs in the vapor-compression cycle for refrigeration and air conditioning and for polymer foams in appliance and building insulations which claim substantial environmental benefits. Among these alternatives are: (1) Hydrocarbon (HC) refrigerants and blowing agents which have zero ozone depleting potential and a negligible global warming potential, (2) CO{sub 2} as a refrigerant and blowing agent, (3) Ammonia (NH{sub 3}) vapor compression systems, (4) Absorption chiller and heat pumping cycles using ammonia/water or lithium bromide/water, and (5) Evacuated panel insulations. This paper summarizes major results and conclusions of the detailed final report on the TEWI-111 study.

  18. Stoichiometry and temperature sensitivity of methanogenesis and CO2 production from saturated polygonal tundra in Barrow, Alaska

    SciTech Connect (OSTI)

    Roy Chowdhury, Taniya; Herndon, Elizabeth M; Phelps, Tommy Joe; Elias, Dwayne A; Gu, Baohua; Liang, Liyuan; Wullschleger, Stan D; Graham, David E

    2015-01-01

    Arctic permafrost ecosystems store ~50% of global belowground carbon (C) that is vulnerable to increased microbial degradation with warmer active layer temperatures and thawing of the near surface permafrost. We used anoxic laboratory incubations to estimate anaerobic CO2 production and methanogenesis in active layer (organic and mineral soil horizons) and permafrost samples from center, ridge and trough positions of water-saturated low-centered polygon in Barrow Environmental Observatory, Barrow AK, USA. Methane (CH4) and CO2 production rates and concentrations were determined at 2, +4, or +8 C for 60 day incubation period. Temporal dynamics of CO2 production and methanogenesis at 2 C showed evidence of fundamentally different mechanisms of substrate limitation and inhibited microbial growth at soil water freezing points compared to warmer temperatures. Nonlinear regression better modeled the initial rates and estimates of Q10 values for CO2 that showed higher sensitivity in the organic-rich soils of polygon center and trough than the relatively drier ridge soils. Methanogenesis generally exhibited a lag phase in the mineral soils that was significantly longer at 2 C in all horizons. Such discontinuity in CH4 production between 2 C and the elevated temperatures (+4 and +8 C) indicated the insufficient representation of methanogenesis on the basis of Q10 values estimated from both linear and nonlinear models. Production rates for both CH4 and CO2 were substantially higher in organic horizons (20% to 40% wt. C) at all temperatures relative to mineral horizons (<20% wt. C). Permafrost horizon (~12% wt. C) produced ~5-fold less CO2 than the active layer and negligible CH4. High concentrations of initial exchangeable Fe(II) and increasing accumulation rates signified the role of iron as terminal electron acceptors for anaerobic C degradation in the mineral horizons.

  19. Size-dependent fluorescence of bioaerosols: Mathematical model using fluorescing and absorbing molecules in bacteria

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hill, Steven C.; Williamson, Chatt C.; Doughty, David C.; Pan, Yong-Le; Santarpia, Joshua L.; Hill, Hanna H.

    2015-02-02

    This paper uses a mathematical model of fluorescent biological particles composed of bacteria and/or proteins (mostly as in Hill et al., 2013 [23]) to investigate the size-dependence of the total fluorescence emitted in all directions. The model applies to particles which have negligible reabsorption of fluorescence within the particle. The specific particles modeled here are composed of ovalbumin and of a generic Bacillus. The particles need not be spherical, and in some cases need not be homogeneous. However, the results calculated in this paper are for spherical homogeneous particles. Light absorbing and fluorescing molecules included in the model are aminomore » acids, nucleic acids, and several coenzymes. Here the excitation wavelength is 266 nm. The emission range, 300 to 370 nm, encompasses the fluorescence of tryptophan. The fluorescence cross section (CF) is calculated and compared with one set of published measured values. We investigate power law (Ady) approximations to CF, where d is diameter, and A and y are parameters adjusted to fit the data, and examine how y varies with d and composition, including the fraction as water. The particle's fluorescence efficiency (QF=CF/geometric-cross-section) can be written for homogeneous particles as QabsRF, where Qabs is the absorption efficiency, and RF, the fraction of the absorbed light emitted as fluorescence, is independent of size and shape. When QF is plotted vs. mid or mi(mr-1)d, where m=mr+imi is the complex refractive index, the plots for different fractions of water in the particle tend to overlap.« less

  20. On the radiation stability of crown ethers in ionic liquids.

    SciTech Connect (OSTI)

    Shkrob, I.; Marin, T.; Dietz, M.

    2011-04-14

    Crown ethers (CEs) are macrocyclic ionophores used for the separation of strontium-90 from acidic nuclear waste streams. Room temperature ionic liquids (ILs) are presently being considered as replacements for traditional molecular solvents employed in such separations. It is desirable that the extraction efficacy obtained with such solvents should not deteriorate in the strong radiation fields generated by decaying radionuclides. This deterioration will depend on the extent of radiation damage to both the IL solvent and the CE solute. While radiation damage to ILs has been extensively studied, the issue of the radiation stability of crown ethers, particularly in an IL matrix, has not been adequately addressed. With this in mind, we have employed electron paramagnetic resonance (EPR) spectroscopy to study the formation of CE-related radicals in the radiolysis of selected CEs in ILs incorporating aromatic (imidazolium and pyridinium) cations. The crown ethers have been found to yield primarily hydrogen loss radicals, H atoms, and the formyl radical. In the low-dose regime, the relative yield of these radicals increases linearly with the mole fraction of the solute, suggesting negligible transfer of the excitation energy from the solvent to the solute; that is, the solvent has a 'radioprotective' effect. The damage to the CE in the loading region of practical interest is relatively low. Under such conditions, the main chemical pathway leading to decreased extraction performance is protonation of the macrocycle. At high radiation doses, sufficient to increase the acidity of the IL solvent significantly, such proton complexes compete with the solvent cations as electron traps. In this regime, the CEs will rapidly degrade as the result of H abstraction from the CE ring by the released H atoms. Thus, the radiation dose to which a CE/IL system is exposed must be maintained at a level sufficiently low to avoid this regime.

  1. The Superoxide Reductase from the Early Diverging Eukaryote Giardia Intestinalis

    SciTech Connect (OSTI)

    Cabelli, D.E.; Testa, F.; Mastronicola, D.; Bordi, E.; Pucillo, L.P.; Sarti, P.; Saraiva, L.M.; Giuffre, A.; Teixeira, M.

    2011-10-15

    Unlike superoxide dismutases (SODs), superoxidereductases (SORs) eliminate superoxide anion (O{sub 2}{sup {sm_bullet}-}) not through its dismutation, but via reduction to hydrogen peroxide (H{sub 2}O{sub 2}) in the presence of an electron donor. The microaerobic protist Giardia intestinalis, responsible for a common intestinal disease in humans, though lacking SOD and other canonical reactive oxygen species-detoxifying systems, is among the very few eukaryotes encoding a SOR yet identified. In this study, the recombinant SOR from Giardia (SOR{sub Gi}) was purified and characterized by pulse radiolysis and stopped-flow spectrophotometry. The protein, isolated in the reduced state, after oxidation by superoxide or hexachloroiridate(IV), yields a resting species (T{sub final}) with Fe{sup 3+} ligated to glutamate or hydroxide depending on pH (apparent pK{sub a} = 8.7). Although showing negligible SOD activity, reduced SOR{sub Gi} reacts with O{sub 2}{sup {sm_bullet}-} with a pH-independent second-order rate constant k{sub 1} = 1.0 x 10{sup 9} M{sup -1} s{sup -1} and yields the ferric-(hydro)peroxo intermediate T{sub 1}; this in turn rapidly decays to the T{sub final} state with pH-dependent rates, without populating other detectable intermediates. Immunoblotting assays show that SOR{sub Gi} is expressed in the disease-causing trophozoite of Giardia. We propose that the superoxide-scavenging activity of SOR in Giardia may promote the survival of this air-sensitive parasite in the fairly aerobic proximal human small intestine during infection.

  2. Derivation of general analytic gradient expressions for density-fitted post-Hartree-Fock methods: An efficient implementation for the density-fitted second-order MllerPlesset perturbation theory

    SciTech Connect (OSTI)

    Bozkaya, U?ur

    2014-09-28

    General analytic gradient expressions (with the frozen-core approximation) are presented for density-fitted post-HF methods. An efficient implementation of frozen-core analytic gradients for the second-order MllerPlesset perturbation theory (MP2) with the density-fitting (DF) approximation (applying to both reference and correlation energies), which is denoted as DF-MP2, is reported. The DF-MP2 method is applied to a set of alkanes, conjugated dienes, and noncovalent interaction complexes to compare the computational cost of single point analytic gradients with MP2 with the resolution of the identity approach (RI-MP2) [F. Weigend and M. Hser, Theor. Chem. Acc. 97, 331 (1997); R. A. Distasio, R. P. Steele, Y. M. Rhee, Y. Shao, and M. Head-Gordon, J. Comput. Chem. 28, 839 (2007)]. In the RI-MP2 method, the DF approach is used only for the correlation energy. Our results demonstrate that the DF-MP2 method substantially accelerate the RI-MP2 method for analytic gradient computations due to the reduced input/output (I/O) time. Because in the DF-MP2 method the DF approach is used for both reference and correlation energies, the storage of 4-index electron repulsion integrals (ERIs) are avoided, 3-index ERI tensors are employed instead. Further, as in case of integrals, our gradient equation is completely avoid construction or storage of the 4-index two-particle density matrix (TPDM), instead we use 2- and 3-index TPDMs. Hence, the I/O bottleneck of a gradient computation is significantly overcome. Therefore, the cost of the generalized-Fock matrix (GFM), TPDM, solution of Z-vector equations, the back transformation of TPDM, and integral derivatives are substantially reduced when the DF approach is used for the entire energy expression. Further application results show that the DF approach introduce negligible errors for closed-shell reaction energies and equilibrium bond lengths.

  3. Ratios of W and Z cross sections at large boson $p_T$ as a constraint on PDFs and background to new physics

    SciTech Connect (OSTI)

    Malik, Sarah Alam; Watt, Graeme

    2014-02-05

    We motivate a measurement of various ratios of W and Z cross sections at the Large Hadron Collider (LHC) at large values of the boson transverse momentum (p T ? M W,Z ). We study the dependence of predictions for these cross-section ratios on the multiplicity of associated jets, the boson p T and the LHC centre-of-mass energy. We present the flavour decomposition of the initial-state partons and an evaluation of the theoretical uncertainties. We also show that the W + /W - ratio is sensitive to the up-quark to down-quark ratio of parton distribution functions (PDFs), while other theoretical uncertainties are negligible, meaning that a precise measurement of the W + /W - ratio at large boson p T values could constrain the PDFs at larger momentum fractions x than the usual inclusive W charge asymmetry. The W /Z ratio is insensitive to PDFs and most other theoretical uncertainties, other than possibly electroweak corrections, and a precise measurement will therefore be useful in validating theoretical predictions needed in data-driven methods, such as using W (? ??) + jets events to estimate the Z(? ??) + jets background in searches for new physics at the LHC. Furthermore, the differential W and Z cross sections themselves, d?/dp T , have the potential to constrain the gluon distribution, provided that theoretical uncertainties from higher-order QCD and electroweak corrections are brought under control, such as by inclusion of anticipated next-to-next-to-leading order QCD corrections.

  4. Mechanism of the hydroxy radical oxidation of methacryoyl peroxynitrate (MPAN) and its pathway toward secondary organic aerosol formation in the atmosphere

    SciTech Connect (OSTI)

    Nguyen, Tran B.; Bates, Kelvin H.; Crounse, J. D.; Schwantes, Rebecca H.; Zhang, Xuan; Kjaergaard, Henrik G.; Surratt, Jason D.; Lin, Peng; Laskin, Alexander; Seinfeld, John H.; Wennberg, P. O.

    2015-01-01

    Methacryoyl peroxynitrate (MPAN), the acylperoxyl nitrate of methacrolein, has been suggested to be an important secondary organic aerosol (SOA) precursor from isoprene oxidation. Yet, the mechanism by which MPAN produces SOA via reaction with the hydroxyl radical (OH) is unclear. We systematically evaluate three proposed mechanisms in controlled chamber experiments and provide the first experimental support for the theoretically-predicted lactone formation pathway from the MPAN + OH reaction, producing hydroxymethyl-methyl-?-lactone (HMML). The decomposition of the MPAN-OH adduct yields HMML + NO3 (~ 75%) and hydroxyacetone + CO + NO3 (~ 25%), out-competing its reaction with atmospheric oxygen. The production of other proposed SOA precursors, e.g., methacrylic acid epoxide (MAE), from MPAN and methacrolein are negligible (< 2 %). Furthermore, we show that the beta-alkenyl moiety of MPAN is critical for lactone formation. Alkyl radicals formed via OH abstraction nstead of addition are thermalized; thus, even if they are structurally identical to the MPAN-OH adduct, they do not decompose to HMML. The SOA formation from HMML, via polyaddition of the lactone to organic compounds, is close to unity under dry conditions. However, the SOA yield is sensitive to particle liquid water and solvated ions. In hydrated sulfate-containing particles, HMML reacts primarily with H2O and aqueous sulfate, producing monomeric 2-methylglyceric acid (2MGA) and the associated organosulfate. 2MGA, a tracer for isoprene SOA, is semivolatile and its volatility increases with decreasing pH in the aerosol water. Conditions that enhance the production of neutral 2MGA will suppress SOA mass from the HMML channel. Considering the liquid water content and pH ranges of ambient particles, MGA may exist largely as a gaseous compound in some parts of the atmosphere.

  5. Scuffing initiation in metals sliding against copper under non-lubricated conditions

    SciTech Connect (OSTI)

    Kovalchenko, A M; Blau, Peter Julian; Qu, Jun; Danyluk, S

    2011-01-01

    Metallic components in sliding contact are sometimes subjected to high-loads with little or no lubrication. Such starved conditions can lead to a phenomenon called scuffing. Various definitions exist for this term, but in the present case, three criteria were used to signal its onset: changes in friction, vibrations, and noise, coupled with surface examination. On this basis, scuffing initiation was determined for seven technically pure metals (Al, Mo, Nb, Ta, Ti, W, Cu) and stainless steel, all rubbing against Cu. A flat-ended pin-on-disk test configuration was used with normal loads of 1-3 N, and with step-wise increases in sliding speed from 0.16 to 2.56 m/s. Al was only weakly resistant to scuffing, presumably due to its solubility in Cu, its high ductility and its relatively low elastic modulus. Niobium provided satisfactory sliding behavior at low speeds and loads, presumably due to protective oxides; however, it scuffed at higher loads when the oxide broke through. Stainless steel, Mo, and Ta had higher friction coefficients than Al and Nb, presumably because the relatively high strengths of the former prevented severe wear even when their oxide films failed. Like Al, Ti scuffs on Cu, probably because of its high relative solubility; however, Ti's higher elastic modulus resists the more severe forms of surface damage than does Al. Of all the materials slid against Cu, W displayed the least scuffing, even under maximum speed and load. Tungsten's negligible solubility in Cu may have reduced its adhesion, and W's high elastic modulus resisted shear-deformation, even at high frictional heating. Self-mated Cu couple scuffed when the speed was increased. The oxides on the Cu surface serve as solid lubricant avoiding scuffing at lower speeds.

  6. Probing violation of the Copernican principle via the integrated Sachs-Wolfe effect

    SciTech Connect (OSTI)

    Tomita, Kenji; Inoue, Kaiki Taro

    2009-05-15

    Recent observational data of supernovae point to {lambda}-dominated flat cosmological models. However, an alternative model in which we happen to live in an underdense region requires no dark energy or modification of gravity. This challenges the Copernican principle. We show that the integrated Sachs-Wolfe (ISW) effect is an excellent discriminator between anti-Copernican inhomogeneous models and the standard Copernican models. As a reference model, we consider an anti-Copernican inhomogeneous model that consists of two inner negatively curved underdense regions and an outer flat Einstein-de Sitter region. We assume that these regions are connected by two thin walls at redshifts z=0.067 and z=0.45. In the inner two regions, the first-order ISW effect is dominant and comparable to that in the concordant flat-{lambda} models. In the outer Einstein-de Sitter region, the first-order ISW effect vanishes but the second-order ISW effect plays a dominant role, while the first-order ISW effect is dominant in the flat-{lambda} models at moderate redshifts. This difference can discriminate the anti-Copernican models from the concordant flat-{lambda} model. At high redshifts, the second-order ISW effect is dominant both in our inhomogeneous model and in the concordant model. In the outer region, moreover, the ISW effect due to large-scale density perturbations with a present matter density contrast {epsilon}{sub m0}<<0.37 is negligible, while the effect due to small-scale density perturbations (such as clusters of galaxies, superclusters, and voids) with {epsilon}{sub m0}>>0.37 would generate anisotropies which are larger than those generated by the ISW effect in the concordant model.

  7. Doping Dependence of the $(\\pi,\\pi)$ Shadow Band in La-Based Cuprates Studied by Angle-Resolved Photoemission Spectroscopy

    SciTech Connect (OSTI)

    Shen, Z. X.

    2011-08-15

    The ({pi},{pi}) shadow band (SB) in La-based cuprate family (La214) was studied by angle-resolved photoemission spectroscopy (ARPES) over a wide doping range from x = 0.01 to x = 0.25. Unlike the well-studied case of the Bi-based cuprate family, an overall strong, monotonic doping dependence of the SB intensity at the Fermi level (E{sub F}) was observed. In contrast to a previous report for the presence of the SB only close to x = 1/8, we found it exists in a wide doping range, associated with a doping-independent ({pi},{pi}) wave vector but strongly doping-dependent intensity: It is the strongest at x {approx} 0.03 and systematically diminishes as the doping increases until it becomes negligible in the overdoped regime. This SB with the observed doping dependence of intensity can in principle be caused by the antiferromagnetic fluctuations or a particular form of low-temperature orthorhombic lattice distortion known to persist up to x {approx} 0.21 in the system, with both being weakened with increasing doping. However, a detailed binding energy dependent analysis of the SB at x = 0.07 does not appear to support the former interpretation, leaving the latter as a more plausible candidate, despite a challenge in quantitatively linking the doping dependences of the SB intensity and the magnitude of the lattice distortion. Our finding highlights the necessity of a careful and global consideration of the inherent structural complications for correctly understanding the cuprate Fermiology and its microscopic implication.

  8. Aqueous foam toxicology evaluation and hazard review

    SciTech Connect (OSTI)

    Archuleta, M.M.

    1995-10-01

    Aqueous foams are aggregates of bubbles mechanically generated by passing air or other gases through a net, screen, or other porous medium that is wetted by an aqueous solution of surface-active foaming agents (surfactants). Aqueous foams are important in modem fire-fighting technology, as well as for military uses for area denial and riot or crowd control. An aqueous foam is currently being developed and evaluated by Sandia National Laboratories (SNL) as a Less-Than-Lethal Weapon for the National Institute of Justice (NIJ). The purpose of this study is to evaluate the toxicity of the aqueous foam developed for the NIJ and to determine whether there are any significant adverse health effects associated with completely immersing individuals without protective equipment in the foam. The toxicity of the aqueous foam formulation developed for NIJ is determined by evaluating the toxicity of the individual components of the foam. The foam is made from a 2--5% solution of Steol CA-330 surfactant in water generated at expansion ratios ranging from 500:1 to 1000:1. SteoI CA-330 is a 35% ammonium laureth sulfate in water and is produced by Stepan Chemical Company and containing trace amounts (<0.1%) of 1,4-dioxane. The results of this study indicate that Steol CA-330 is a non-toxic, mildly irritating, surfactant that is used extensively in the cosmetics industry for hair care and bath products. Inhalation or dermal exposure to this material in aqueous foam is not expected to produce significant irritation or systemic toxicity to exposed individuals, even after prolonged exposure. The amount of 1,4-dioxane in the surfactant, and subsequently in the foam, is negligible and therefore, the toxicity associated with dioxane exposure is not significant. In general, immersion in similar aqueous foams has not resulted in acute, immediately life-threatening effects, or chronic, long-term, non-reversible effects following exposure.

  9. Thermoacoustic imaging using heavy ion beams

    SciTech Connect (OSTI)

    Claytor, T.N.; Tesmer, J.R.; Deemer, B.C.; Murphy, J.C.

    1995-10-01

    Ion beams have been used for surface modification, semiconductor device fabrication and for material analysis, which makes ion-material interactions of significant importance. Ion implantation will produce new compositions near the surface by ion mixing or directly by implanting desired ions. Ions exchange their energy to the host material as they travel into the material by several different processes. High energy ions ionize the host atoms before atomic collisions transfer the remaining momentum and stop the incident ion. As they penetrate the surface, the low energy ions ionize the host atoms, but also have a significantly large momentum transfer mechanism near the surface of the material. This leads to atoms, groups of atoms and electrons being ejected from the surface, which is the momentum transfer process of sputtering. This talk addresses the acoustic waves generated during ion implantation using modulated heavy ion beams. The mechanisms for elastic wave generation during ion implantation, in the regimes where sputtering is significant and where implantation is dominant and sputtering is negligible, has been studied. The role of momentum transfer and thermal energy production during ion implantation was compared to laser generated elastic waves in an opaque solid as a reference, since laser generated ultrasound has been extensively studied and is fairly well understood. The thermoelastic response dominated in both high and low ion energy regimes since, apparently, more energy is lost to thermal heat producing mechanisms than momentum transfer processes. The signal magnitude was found to vary almost linearly with incident energy as in the laser thermoelastic regime. The time delays for longitudinal and shear waves-were characteristic of those expected for a purely thermal heating source. The ion beams are intrinsically less sensitive to the albedo of the surface.

  10. TH-A-18C-06: A Scatter Elimination Scheme for Cone Beam CT Using An Oscillating Narrow Beam

    SciTech Connect (OSTI)

    Yan, H; Folkerts, M; Jia, X; Jiang, S; Xu, Y

    2014-06-15

    Purpose: While cone beam CT (CBCT) has been widely used in image guided radiation therapy, its low image quality, primarily caused by scattered x-rays, hinders advanced clinical applications, e.g., CBCT based on-line adaptive re-planning. We propose in this abstract a new scheme called oscillating narrow beam CBCT (ONB-CBCT) to eliminate scatter signals. Methods: ONB-CBCT consists of two major components. 1) Oscillating narrow beam (ONB) scan and 2) partitioned flat panel containing multiple individual detector strips and their own readouts. Both the beam oscillation and detector partition are along the superior-inferior (SI) direction. During data acquisition, at a given projection, the narrow beam sweep through the detector region, and different portions of the detector acquires projection data in synchrony with the narrow beam. ONB can be generated by a rotating slit collimator design with conventional tube with single focal spot, or by directly using a new source with multiple focal spots. A proof-of-principle study via Monte Carlo simulation is conducted to demonstrate the feasibility of ONB-CBCT. Results: As the beam becomes narrower, more and more scatter signals are eliminated. For the case with a bowtie filter and using 15 ONBs, the maximum and the average intensity error due to scatter are below 20 and 10 HU, respectively. Conclusion: ONB yields a narrowed exposure field at each snapshot and hence an inherently negligible scatter effect. Meanwhile, the individualized detector units guarantee high frame rate detection and hence a same large volume coverage as that in conventional CBCT. In summary, ONB-CBCT is a promising design to achieve high-quality CBCT imaging. This study is supported in part by NIH (1R01CA154747-01)

  11. Feasibility study for a 10-MM-GPY fuel ethanol plant, Brady Hot Springs, Nevada. Volume 1. Process and plant design

    SciTech Connect (OSTI)

    Not Available

    1980-09-01

    An investigation was performed to determine the technical and economic viability of constructing and operating a geothermally heated, biomass, motor fuel alcohol plant at Brady's Hot Springs. The results of the study are positive, showing that a plant of innovative, yet proven design can be built to adapt current commerical fermentation-distillation technology to the application of geothermal heat energy. The specific method of heat production from the Brady's Hot Spring wells has been successful for some time at an onion drying plant. Further development of the geothermal resource to add the capacity needed for an ethanol plant is found to be feasible for a plant sized to produce 10 million gallons of motor fuel grade ethanol per year. A very adequate supply of feedgrains is found to be available for use in the plant without impact on the local or regional feedgrain market. The effect of diverting supplies from the animal feedlots in Northern Nevada and California will be mitigated by the by-product output of high-protein feed supplements that the plant will produce. The plant will have a favorable impact on the local farming economies of Fallon, Lovelock, Winnemucca and Elko, Nevada. It will make a positive and significant socioeconomic contribution to Churchill County, providing direct employment for an additional 61 persons. Environmental impact will be negligible, involving mostly a moderate increase in local truck traffic and railroad siding activity. The report is presented in two volumes. Volume 1 deals with the technical design aspects of the plant. The second volume addresses the issue of expanded geothermal heat production at Brady's Hot Springs, goes into the details of feedstock supply economics, and looks at the markets for the plant's primary ethanol product, and the markets for its feed supplement by-products. The report concludes with an analysis of the economic viability of the proposed project.

  12. Dissecting ion-specific dielectric spectra of sodium-halide solutions into solvation water and ionic contributions

    SciTech Connect (OSTI)

    Rinne, Klaus F.; Netz, Roland R.; Gekle, Stephan

    2014-12-07

    Using extensive equilibrium molecular dynamics simulations we determine the dielectric spectra of aqueous solutions of NaF, NaCl, NaBr, and NaI. The ion-specific and concentration-dependent shifts of the static dielectric constants and the dielectric relaxation times match experimental results very well, which serves as a validation of the classical and non-polarizable ionic force fields used. The purely ionic contribution to the dielectric response is negligible, but determines the conductivity of the salt solutions. The ion-water cross correlation contribution is negative and reduces the total dielectric response by about 5%-10% for 1?M solutions. The dominating water dielectric response is decomposed into different water solvation shells and ion-pair configurations, by this the spectral blue shift and the dielectric decrement of salt solutions with increasing salt concentration is demonstrated to be primarily caused by first-solvation shell water. With rising salt concentration the simulated spectra show more pronounced deviations from a single-Debye form and can be well described by a Cole-Cole fit, in quantitative agreement with experiments. Our spectral decomposition into ionic and different water solvation shell contributions does not render the individual contributions more Debye-like, this suggests the non-Debye-like character of the dielectric spectra of salt solutions not to be due to the superposition of different elementary relaxation processes with different relaxation times. Rather, the non-Debye-like character is likely to be an inherent spectral signature of solvation water around ions.

  13. Instrument uncertainty effect on calculation of absolute humidity using dewpoint, wet-bulb, and relative humidity sensors

    SciTech Connect (OSTI)

    Slayzak, S.J.; Ryan, J.P.

    1998-04-01

    As part of the US Department of Energy`s Advanced Desiccant Technology Program, the National Renewable Energy Laboratory (NREL) is characterizing the state-of-the-art in desiccant dehumidifiers, the key component of desiccant cooling systems. The experimental data will provide industry and end users with independent performance evaluation and help researchers assess the energy savings potential of the technology. Accurate determination of humidity ratio is critical to this work and an understanding of the capabilities of the available instrumentation is central to its proper application. This paper compares the minimum theoretical random error in humidity ratio calculation for three common measurement methods to give a sense of the relative maximum accuracy possible for each method assuming systematic errors can be made negligible. A series of experiments conducted also illustrate the capabilities of relative humidity sensors as compared to dewpoint sensors in measuring the grain depression of desiccant dehumidifiers. These tests support the results of the uncertainty analysis. At generally available instrument accuracies, uncertainty in calculated humidity ratio for dewpoint sensors is determined to be constant at approximately 2%. Wet-bulb sensors range between 2% and 6% above 10 g/kg (4%--15% below), and relative humidity sensors vary between 4% above 90% rh and 15% at 20% rh. Below 20% rh, uncertainty for rh sensors increases dramatically. Highest currently attainable accuracies bring dewpoint instruments down to 1% uncertainty, wet bulb to a range of 1%--3% above 10 g/kg (1.5%--8% below), and rh sensors between 1% and 5%.

  14. Intrinsic alignments of galaxies in the MassiveBlack-II simulation: Analysis of two-point statistics

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tenneti, Ananth; Singh, Sukhdeep; Mandelbaum, Rachel; Matteo, Tiziana Di; Feng, Yu; Khandai, Nishikanta

    2015-03-11

    The intrinsic alignment of galaxies with the large-scale density field in an important astrophysical contaminant in upcoming weak lensing surveys. We present detailed measurements of the galaxy intrinsic alignments and associated ellipticity-direction (ED) and projected shape (wg₊) correlation functions for galaxies in the cosmological hydrodynamic MassiveBlack-II (MB-II) simulation. We carefully assess the effects on galaxy shapes, misalignment of the stellar component with the dark matter shape and two-point statistics of iterative weighted (by mass and luminosity) definitions of the (reduced and unreduced) inertia tensor. We find that iterative procedures must be adopted for a reliable measurement of the reduced tensormore » but that luminosity versus mass weighting has only negligible effects. Both ED and wg₊ correlations increase in amplitude with subhalo mass (in the range of 10¹⁰ – 6.0 X 10¹⁴h⁻¹ M⊙), with a weak redshift dependence (from z = 1 to z = 0.06) at fixed mass. At z ~ 0.3, we predict a wg₊ that is in reasonable agreement with SDSS LRG measurements and that decreases in amplitude by a factor of ~ 5–18 for galaxies in the LSST survey. We also compared the intrinsic alignment of centrals and satellites, with clear detection of satellite radial alignments within the host halos. Finally, we show that wg₊ (using subhalos as tracers of density and wδ (using dark matter density) predictions from the simulations agree with that of non-linear alignment models (NLA) at scales where the 2-halo term dominates in the correlations (and tabulate associated NLA fitting parameters). The 1-halo term induces a scale dependent bias at small scales which is not modeled in the NLA model.« less

  15. ON THE EFFECT OF GIANT PLANETS ON THE SCATTERING OF PARENT BODIES OF IRON METEORITE FROM THE TERRESTRIAL PLANET REGION INTO THE ASTEROID BELT: A CONCEPT STUDY

    SciTech Connect (OSTI)

    Haghighipour, Nader; Scott, Edward R. D.

    2012-04-20

    In their model for the origin of the parent bodies of iron meteorites, Bottke et al. proposed differentiated planetesimals, formed in 1-2 AU during the first 1.5 Myr, as the parent bodies, and suggested that these objects and their fragments were scattered into the asteroid belt as a result of interactions with planetary embryos. Although viable, this model does not include the effect of a giant planet that might have existed or been growing in the outer regions. We present the results of a concept study where we have examined the effect of a planetary body in the orbit of Jupiter on the early scattering of planetesimals from the terrestrial region into the asteroid belt. We integrated the orbits of a large battery of planetesimals in a disk of planetary embryos and studied their evolutions for different values of the mass of the planet. Results indicate that when the mass of the planet is smaller than 10 M{sub Circled-Plus }, its effects on the interactions among planetesimals and planetary embryos are negligible. However, when the planet mass is between 10 and 50 M{sub Circled-Plus }, simulations point to a transitional regime with {approx}50 M{sub Circled-Plus} being the value for which the perturbing effect of the planet can no longer be ignored. Simulations also show that further increase of the mass of the planet strongly reduces the efficiency of the scattering of planetesimals from the terrestrial planet region into the asteroid belt. We present the results of our simulations and discuss their possible implications for the time of giant planet formation.

  16. Andromeda (M31) optical and infrared disk survey. I. Insights in wide-field near-IR surface photometry

    SciTech Connect (OSTI)

    Sick, Jonathan; Courteau, Stphane; Cuillandre, Jean-Charles; McDonald, Michael; De Jong, Roelof; Tully, R. Brent

    2014-05-01

    We present wide-field near-infrared J and K{sub s} images of the Andromeda Galaxy (M31) taken with WIRCam at the Canada-France-Hawaii Telescope as part of the Andromeda Optical and Infrared Disk Survey. This data set allows simultaneous observations of resolved stars and near-infrared (NIR) surface brightness across M31's entire bulge and disk (within R = 22 kpc), permitting a direct test of the stellar composition of near-infrared light in a nearby galaxy. Here we develop NIR observation and reduction methods to recover a uniform surface brightness map across the 3 1 disk of M31 with 27 WIRCam fields. Two sky-target nodding strategies are tested, and we find that strictly minimizing sky sampling latency cannot improve background subtraction accuracy to better than 2% of the background level due to spatio-temporal variations in the NIR skyglow. We fully describe our WIRCam reduction pipeline and advocate using flats built from night-sky images over a single night, rather than dome flats that do not capture the WIRCam illumination field. Contamination from scattered light and thermal background in sky flats has a negligible effect on the surface brightness shape compared to the stochastic differences in background shape between sky and galaxy disk fields, which are ?0.3% of the background level. The most dramatic calibration step is the introduction of scalar sky offsets to each image that optimizes surface brightness continuity. Sky offsets reduce the mean surface brightness difference between observation blocks from 1% to <0.1% of the background level, though the absolute background level remains statistically uncertain to 0.15% of the background level. We present our WIRCam reduction pipeline and performance analysis to give specific recommendations for the improvement of NIR wide-field imaging methods.

  17. Irradiation-assisted stress corrosion cracking of austenitic stainless steels: Recent progress and new approaches

    SciTech Connect (OSTI)

    Chung, H.M.; Ruther, W.E.; Sanecki, J.E.; Hins, A.; Zaluzec, N.J.; Kassner, T.F.

    1996-09-01

    Irradiation-assisted stress corrosion cracking (IASCC) of several types of BWR field components fabricated from solution-annealed austenitic stainless steels (SSs), including a core internal weld, were investigated by means of slow-strain-rate test (SSRT), scanning electron microscopy (SEM), Auger electron spectroscopy (AES), and field-emission-gun advanced analytical electron microscopy (FEG-AAEM). Based on the results of the tests and analyses, separate effects of neutron fluence, tensile properties, alloying elements and major impurities identified in the American Society for Testing and Materials (ASTM) specifications, minor impurities, water chemistry, and fabrication-related variables were determined. The results indicate strongly that minor impurities not specified by the ASTM-specifications play important roles, probably through a complex synergism with grain-boundary Cr depletion. These impurities, typically associated with steelmaking and component fabrication processes, are very low or negligible in solubility in steels and are the same impurities that have been known to promote intergranular SCC significantly when they are present in water as ions or soluble compounds. It seems obvious that IASCC is a complex integral problem which involves many variables that are influenced strongly by not only irradiation conditions, water chemistry, and stress but also iron and steelmaking processes, fabrication of the component, and joining and welding. Therefore, for high-stress components in particular, it would be difficult to mitigate IASCC problems at high fluence based on the consideration of water chemistry alone, and other considerations based on material composition and fabrication procedure would be necessary as well.

  18. SU-E-T-98: Dependence of Radiotherapy Couch Transmission Factors On Field Size and Couch-Isocenter Distance

    SciTech Connect (OSTI)

    Benhabib, S; Duan, J; Wu, X; Cardan, R; Shen, S; Huang, M; Popple, R; Brezovich, I

    2014-06-01

    Purpose: The dosimetric effect of the treatment couch is non-negligible in today's radiotherapy treatment. To accurately include couch in dose calculation, we investigated the dependence of couch transmission factors on field size and couch-isocenter distance. Methods: Couch transmission factors for Varian Exact Couch were determined by taking the ratios of ionization of a posterior-anterior beam with and without the couch in the beam path. Measurements were performed at the isocenter using a PTW cylindrical ionization chamber (Model 31030) with an Aluminum buildup cap of 1.1 cm thick for the 6 MV photon beam. Ionization readings for beam sizes ranging from 2 2 cm2 to 40 40 cm2 were taken. Transmission factors for couch-isocenter distances ranging from 3 cm to 20 cm were also investigated. Results: The couch transmission factors increased with the field size approximately in an exponential manner. For the field sizes that we tested, the transmission factor ranged from 0.976 to 0.992 for couch-isocenter distance of 3 cm. The transmission factor was also monotonically dependent on couch-isocenter separation distance, but in a lighter magnitude. For the tested couch heights, the transmission factor ranged from 0.974 0.972 for 2 2 cm2 field size and 0.992 0.986 for 40 40 cm2 field size. The dependence on couch-isocenter distance is stronger for larger field size. Conclusions: The transmission factor of a radiotherapy treatment couch increases with field size of the radiation beam and its distance from the isocenter. Such characterization of the couch transmission factor helps improve the accuracy of couch modeling for radiotherapy treatment planning.

  19. PROSPECTS FOR PROBING THE SPACETIME OF Sgr A* WITH PULSARS

    SciTech Connect (OSTI)

    Liu, K.; Wex, N.; Kramer, M.; Cordes, J. M.; Lazio, T. J. W.

    2012-03-01

    The discovery of radio pulsars in compact orbits around Sgr A* would allow an unprecedented and detailed investigation of the spacetime of this supermassive black hole. This paper shows that pulsar timing, including that of a single pulsar, has the potential to provide novel tests of general relativity, in particular its cosmic censorship conjecture and no-hair theorem for rotating black holes. These experiments can be performed by timing observations with 100 {mu}s precision, achievable with the Square Kilometre Array for a normal pulsar at frequency above 15 GHz. Based on the standard pulsar timing technique, we develop a method that allows the determination of the mass, spin, and quadrupole moment of Sgr A*, and provides a consistent covariance analysis of the measurement errors. Furthermore, we test this method in detailed mock data simulations. It seems likely that only for orbital periods below {approx}0.3 yr is there the possibility of having negligible external perturbations. For such orbits, we expect a {approx}10{sup -3} test of the frame dragging and a {approx}10{sup -2} test of the no-hair theorem within five years, if Sgr A* is spinning rapidly. Our method is also capable of identifying perturbations caused by distributed mass around Sgr A*, thus providing high confidence in these gravity tests. Our analysis is not affected by uncertainties in our knowledge of the distance to the Galactic center, R{sub 0}. A combination of pulsar timing with the astrometric results of stellar orbits would greatly improve the measurement precision of R{sub 0}.

  20. Gravitational waves and stalled satellites from massive galaxy mergers at z ? 1

    SciTech Connect (OSTI)

    McWilliams, Sean T.; Pretorius, Frans; Ostriker, Jeremiah P.

    2014-07-10

    We present a model for merger-driven evolution of the mass function for massive galaxies and their central supermassive black holes at late times. We discuss the current observational evidence in favor of merger-driven massive galaxy evolution during this epoch, and demonstrate that the observed evolution of the mass function can be reproduced by evolving an initial mass function under the assumption of negligible star formation. We calculate the stochastic gravitational wave signal from the resulting black hole binary mergers in the low redshift universe (z ? 1) implied by this model, and find that this population has a signal-to-noise ratio 2 to 5 larger than previous estimates for pulsar timing arrays, with a (2?, 3?) lower limit within this model of h{sub c}(f = 1 yr{sup 1}) = (1.1 10{sup 15}, 6.8 10{sup 16}). The strength of this signal is sufficient to make it detectable with high probability under conservative assumptions within the next several years. A principle reason that this result is larger than previous estimates is our use of a recent recalibration of the black hole-stellar mass correlation for the brightest cluster galaxies, which increases our estimate by a factor of ?2 relative to past results. For cases where a galaxy merger fails to lead to a black hole merger, we estimate the probability for a given number of satellite black holes to remain within a massive host galaxy, and interpret the result in light of ULX observations. We find that in rare cases, wandering supermassive black holes may be bright enough to appear as ULXs.

  1. WEIGHING GALAXY CLUSTERS WITH GAS. I. ON THE METHODS OF COMPUTING HYDROSTATIC MASS BIAS

    SciTech Connect (OSTI)

    Lau, Erwin T.; Nagai, Daisuke; Nelson, Kaylea

    2013-11-10

    Mass estimates of galaxy clusters from X-ray and Sunyeav-Zel'dovich observations assume the intracluster gas is in hydrostatic equilibrium with their gravitational potential. However, since galaxy clusters are dynamically active objects whose dynamical states can deviate significantly from the equilibrium configuration, the departure from the hydrostatic equilibrium assumption is one of the largest sources of systematic uncertainties in cluster cosmology. In the literature there have been two methods for computing the hydrostatic mass bias based on the Euler and the modified Jeans equations, respectively, and there has been some confusion about the validity of these two methods. The word 'Jeans' was a misnomer, which incorrectly implies that the gas is collisionless. To avoid further confusion, we instead refer these methods as 'summation' and 'averaging' methods respectively. In this work, we show that these two methods for computing the hydrostatic mass bias are equivalent by demonstrating that the equation used in the second method can be derived from taking spatial averages of the Euler equation. Specifically, we identify the correspondences of individual terms in these two methods mathematically and show that these correspondences are valid to within a few percent level using hydrodynamical simulations of galaxy cluster formation. In addition, we compute the mass bias associated with the acceleration of gas and show that its contribution is small in the virialized regions in the interior of galaxy clusters, but becomes non-negligible in the outskirts of massive galaxy clusters. We discuss future prospects of understanding and characterizing biases in the mass estimate of galaxy clusters using both hydrodynamical simulations and observations and their implications for cluster cosmology.

  2. Intrinsic alignments of galaxies in the MassiveBlack-II simulation: Analysis of two-point statistics

    SciTech Connect (OSTI)

    Tenneti, Ananth; Singh, Sukhdeep; Mandelbaum, Rachel; Matteo, Tiziana Di; Feng, Yu; Khandai, Nishikanta

    2015-03-11

    The intrinsic alignment of galaxies with the large-scale density field in an important astrophysical contaminant in upcoming weak lensing surveys. We present detailed measurements of the galaxy intrinsic alignments and associated ellipticity-direction (ED) and projected shape (wg?) correlation functions for galaxies in the cosmological hydrodynamic MassiveBlack-II (MB-II) simulation. We carefully assess the effects on galaxy shapes, misalignment of the stellar component with the dark matter shape and two-point statistics of iterative weighted (by mass and luminosity) definitions of the (reduced and unreduced) inertia tensor. We find that iterative procedures must be adopted for a reliable measurement of the reduced tensor but that luminosity versus mass weighting has only negligible effects. Both ED and wg? correlations increase in amplitude with subhalo mass (in the range of 10? 6.0 X 10?h? M?), with a weak redshift dependence (from z = 1 to z = 0.06) at fixed mass. At z ~ 0.3, we predict a wg? that is in reasonable agreement with SDSS LRG measurements and that decreases in amplitude by a factor of ~ 518 for galaxies in the LSST survey. We also compared the intrinsic alignment of centrals and satellites, with clear detection of satellite radial alignments within the host halos. Finally, we show that wg? (using subhalos as tracers of density and w? (using dark matter density) predictions from the simulations agree with that of non-linear alignment models (NLA) at scales where the 2-halo term dominates in the correlations (and tabulate associated NLA fitting parameters). The 1-halo term induces a scale dependent bias at small scales which is not modeled in the NLA model.

  3. General circulation model calculations of the direct radiative forcing by anthropogenic sulfate and fossil-fuel soot aerosol

    SciTech Connect (OSTI)

    Haywood, J.M.; Roberts, D.L.; Slingo, A.

    1997-07-01

    A new radiation code within a general circulation model is used to assess the direct solar and thermal radiative forcing by sulfate aerosol of anthropogenic origin and soot aerosol from fossil-fuel burning. The radiative effects of different aerosol profiles, relative humidity parameterizations, chemical compositions, and internal and external mixtures of the two aerosol types are investigated. The contribution to the radiative forcing from cloudy sky regions is found to be negligible for sulfate aerosol; this is in contrast to recent studies where the cloudy sky contribution was estimated using a method in which the spatial correlation between cloud amount and sulfate burden was ignored. However, the radiative forcing due to fossil-fuel soot aerosol is enhanced in cloudy regions if soot aerosol exists within or above the cloud. The global solar radiative forcing due to sulfate aerosol is estimated to be -0.38 W m{sup -2} and the global thermal radiative forcing is estimated to be +0.01 W m{sup -2}. The hemispheric mean radiative forcings vary by only about 10% for reasonable assumptions about the chemical form of the sulfate aerosol and the relative humidity dependence; the uncertainties in the aerosol loading are far more significant. If a soot/sulfate mass ratio of 0.075 is assumed, then the global solar radiative forcing weakens to -0.18 W m{sup -2} for an external mixture and weakens further for an internal mixture. Additionally, the spatial distribution of the radiative forcing shows strong negative/positive forcing contrasts that may influence the dynamical response of the atmosphere. Although these results are extremely sensitive to the adopted soot/sulfate ratio and the assumed vertical profile, they indicate that fossil-fuel soot aerosol may exert a nonnegligible radiative forcing and emphasize the need to consider each anthropogenic aerosol species. 58 refs., 8 figs., 1 tab.

  4. Predicted thermal performance of triple vacuum glazing

    SciTech Connect (OSTI)

    Fang, Yueping; Hyde, Trevor J.; Hewitt, Neil

    2010-12-15

    The simulated triple vacuum glazing (TVG) consists of three 4 mm thick glass panes with two vacuum gaps, with each internal glass surface coated with a low-emittance coating with an emittance of 0.03. The two vacuum gaps are sealed by an indium based sealant and separated by a stainless steel pillar array with a height of 0.12 mm and a pillar diameter of 0.3 mm spaced at 25 mm. The thermal transmission at the centre-of-glazing area of the TVG was predicted to be 0.26 W m{sup -2} K{sup -1}. The simulation results show that although the thermal conductivity of solder glass (1 W m{sup -1} K{sup -1}) and indium (83.7 W m{sup -1} K{sup -1}) are very different, the difference in thermal transmission of TVGs resulting from the use of an indium and a solder glass edge seal was 0.01 W m{sup -2} K{sup -1}. This is because the edge seal is so thin (0.12 mm), consequently there is a negligible temperature drop across it irrespective of the material that the seal is made from relative to the total temperature difference across the glazing. The results also show that there is a relatively large increase in the overall thermal conductance of glazings without a frame when the width of the indium edge seal is increased. Increasing the rebate depth in a solid wood frame decreased the heat transmission of the TVG. The overall heat transmission of the simulated 0.5 m by 0.5 m TVG was 32.6% greater than that of the 1 m by 1 m TVG, since heat conduction through the edge seal of the small glazing has a larger contribution to the total glazing heat transfer than that of the larger glazing system. (author)

  5. Progress towards a PETN Lifetime Prediction Model

    SciTech Connect (OSTI)

    Burnham, A K; Overturf III, G E; Gee, R; Lewis, P; Qiu, R; Phillips, D; Weeks, B; Pitchimani, R; Maiti, A; Zepeda-Ruiz, L; Hrousis, C

    2006-09-11

    Dinegar (1) showed that decreases in PETN surface area causes EBW detonator function times to increase. Thermal aging causes PETN to agglomerate, shrink, and densify indicating a ''sintering'' process. It has long been a concern that the formation of a gap between the PETN and the bridgewire may lead to EBW detonator failure. These concerns have led us to develop a model to predict the rate of coarsening that occurs with age for thermally driven PETN powder (50% TMD). To understand PETN contributions to detonator aging we need three things: (1) Curves describing function time dependence on specific surface area, density, and gap. (2) A measurement of the critical gap distance for no fire as a function of density and surface area for various wire configurations. (3) A model describing how specific surface area, density and gap change with time and temperature. We've had good success modeling high temperature surface area reduction and function time increase using a phenomenological deceleratory kinetic model based on a distribution of parallel nth-order reactions having evenly spaced activation energies where weighing factors of the reactions follows a Gaussian distribution about the reaction with the mean activation energy (Figure 1). Unfortunately, the mean activation energy derived from this approach is high (typically {approx}75 kcal/mol) so that negligible sintering is predicted for temperatures below 40 C. To make more reliable predictions, we've established a three-part effort to understand PETN mobility. First, we've measured the rates of step movement and pit nucleation as a function of temperature from 30 to 50 C for single crystals. Second, we've measured the evaporation rate from single crystals and powders from 105 to 135 C to obtain an activation energy for evaporation. Third, we've pursued mechanistic kinetic modeling of surface mobility, evaporation, and ripening.

  6. Approaching attometer laser vibrometry

    SciTech Connect (OSTI)

    Rembe, Christian; Kadner, Lisa; Giesen, Moritz

    2014-05-27

    The heterodyne two-beam interferometer has been proven to be the optimal solution for laser-Doppler vibrometry regarding accuracy and signal robustness. The theoretical resolution limit for a two-beam interferometer of laser class 3R (up to 5 mW visible measurement-light) is in the regime of a few femtometer per square-root Hertz and well suited to study vibrations in microstructures. However, some new applications of RF-MEM resonators, nanostructures, and surface-nano-defect detection require resolutions beyond that limit. The resolution depends only on the noise and the sensor sensitivity to specimen displacements. The noise is already defined in nowadays systems by the quantum nature of light for a properly designed optical sensor and more light would lead to an inacceptable influence like heating of a very tiny structure. Thus, noise can only be improved by squeezed-light techniques which require a negligible loss of measurement light which is impossible for almost all technical measurement tasks. Thus, improving the sensitivity is the only possible path which could make attometer laser vibrometry possible. Decreasing the measurement wavelength would increase the sensitivity but would also increase the photon shot noise. In this paper, we discuss an approach to increase the sensitivity by assembling an additional mirror between interferometer and specimen to form an optical cavity. A detailed theoretical analysis of this setup is presented and we derive the resolution limit, discuss the main contributions to the uncertainty budget, and show a first experiment proving the sensitivity amplification of our approach.

  7. Improvement of Prostate Treatment by Anterior Proton Fields

    SciTech Connect (OSTI)

    Tang, Shikui; Both, Stefan; Bentefour, Hassan; Paly, Jonathan J.; Tochner, Zelig; Efstathiou, Jason; Lu, Hsiao-Ming

    2012-05-01

    Purpose: We performed a treatment planning study to demonstrate the potential dosimetric benefits of anterior-oriented fields for prostate irradiation by proton beam. A novel in vivo beam range control method shows millimeter accuracy, suggesting that such fields could be safely used to spare the rectum given the sharp distal penumbra of protons. Methods and Materials: Ten prostate patients treated with water-filled endorectal balloon were selected. Bilateral fields were planned following the conventional treatment protocol. Three anterior-oriented fields (0, +30, -30 Degree-Sign ) were planned, with the range compensators manually adjusted to improve rectal sparing. Dose distributions to the clinical target volume, rectum, anterior rectal wall (ARW), bladder, bladder wall (BW), and femoral heads were compared for: A) equally weighted bilateral fields, B) a single straight anterior field, and C) two equally weighted anterior-oblique fields. Results: The anterior-oriented fields required much less beam energy, {approx}10 cm water equivalent path length less than lateral fields. For ARW, the V{sub 95%} for Plans A, B, and C were 39%, 8%, and 6%, respectively; the corresponding V{sub 80%} were 59%, 27%, and 26%, respectively (p = 0.002 when Plan A was compared with B or C). Plan B irradiated a larger volume of BW than did Plan A by 3% at V{sub 95%}, 11% at V{sub 80%}, and 16% at V{sub 50%} (p = 0.002), whereas Plan C differs little from Plan A for BW at these dose levels. The femoral heads received {approx}40% of the prescription dose in Plan A, but negligible dose in Plans B and C. Conclusions: Compared to lateral fields, anterior-oriented fields can significantly reduce dose to the ARW, particularly at high dose levels. These fields alone, or in combination with lateral fields, allow for the possibility of either reducing treatment toxicity at current prescription doses or further dose escalation in the treatment of prostate cancer.

  8. Three-body Coulomb interaction effects in the final state of the {sup 208}Pb({sup 8}B,{sup 7}Be p){sup 208}Pb Coulomb breakup reaction

    SciTech Connect (OSTI)

    Alt, E.O.; Irgaziev, B.F.; Mukhamedzhanov, A.M.

    2005-02-01

    The photodissociation reaction {sup 8}B+{gamma}{yields}{sup 7}Be+p is used to provide information on the astrophysical S{sub 17} factor of the inverse radiative capture reaction, knowledge of which is crucial for an estimation of the high-energy neutrino flux from the sun. Since, at present, the Coulomb field of a fully stripped nucleus serves as the source of the photons, an adequate analysis requires a genuine three-body treatment of this reaction. Among the uncertainties still affecting present analyses, the possible modification of the dissociation cross section by the post-decay acceleration of the fragments {sup 7}Be and p in the target field plays a major role. Working with the prior form of the dissociation amplitude, we first discuss why the standard approximation for the final-state wave function is not appropriate for a proper investigation of this problem; instead, use of a genuine three-particle wave function for the final state proves to be mandatory. Such is provided by a recently proposed wave function for three charged particles in the continuum [A. M. Mukhamedzhanov and M. Lieber, Phys. Rev. A 54, 3078 (1996)] which possesses all the essential features required. It is an exact solution of the three-body Schroedinger equation, but only asymptotically, i.e., for large distances. Therefore, only qualitative predictions can be made currently, such as predicting the kinematic configurations in which post-decay acceleration effects play a negligible role. Explicit calculations are presented for the single and the double differential cross sections for the {sup 208}Pb({sup 8}B,{sup 7}Be p){sup 208}Pb Coulomb breakup reaction. We also investigate the influence of the E2 multipole and find its contribution to be small for small scattering angles, but comparable to the one from the E1 dipole for large scattering angles.

  9. Measurements of differential and double-differential Drell-Yan cross sections in proton-proton collisions at $\\sqrt{s}$ = 8 TeV

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Khachatryan, Vardan

    2015-04-09

    Measurements of the differential and double-differential Drell-Yan cross sections in the dielectron and dimuon channels are presented. They are based on proton-proton collision data at $\\sqrt{s}$ - 8 TeV recorded with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 inverse femtobarns. The measured inclusive cross section in the Z peak region (60-120 GeV), obtained from the combination of the dielectron and dimuon channels, is 1138 +/- 8 (exp) +/- 25 (theo) +/- 30 (lumi) pb, where the statistical uncertainty is negligible. The differential cross section $d\\sigma/dm$ in the dilepton mass range 15 to 2000moreGeV is measured and corrected to the full phase space. The double-differential cross section $d^2 \\sigma / d(m) d(abs(y))$ is also measured over the mass range 20 to 1500 GeV and absolute dilepton rapidity from 0 to 2.4. In addition, the ratios of the normalized differential cross sections measured at $\\sqrt{s}$ = 7 and 8 TeV are presented. These measurements are compared to the predictions of perturbative QCD at next-to-leading and next-to-next-to-leading (NNLO) orders using various sets of parton distribution functions (PDFs). The results agree with the NNLO theoretical predictions computed with FEWZ 3.1 using the CT10 NNLO and NNPDF2.1 NNLO PDFs. The measured double-differential cross section and ratio of normalized differential cross sections are sufficiently precise to constrain the proton PDFs.less

  10. Evaluating temperature and fuel stratification for heat-release rate control in a reactivity-controlled compression-ignition engine using optical diagnostics and chemical kinetics modeling

    SciTech Connect (OSTI)

    Musculus, Mark P. B.; Kokjohn, Sage L.; Reitz, Rolf D.

    2015-04-23

    We investigated the combustion process in a dual-fuel, reactivity-controlled compression-ignition (RCCI) engine using a combination of optical diagnostics and chemical kinetics modeling to explain the role of equivalence ratio, temperature, and fuel reactivity stratification for heat-release rate control. An optically accessible engine is operated in the RCCI combustion mode using gasoline primary reference fuels (PRF). A well-mixed charge of iso-octane (PRF = 100) is created by injecting fuel into the engine cylinder during the intake stroke using a gasoline-type direct injector. Later in the cycle, n-heptane (PRF = 0) is delivered through a centrally mounted diesel-type common-rail injector. This injection strategy generates stratification in equivalence ratio, fuel blend, and temperature. The first part of this study uses a high-speed camera to image the injection events and record high-temperature combustion chemiluminescence. Moreover, the chemiluminescence imaging showed that, at the operating condition studied in the present work, mixtures in the squish region ignite first, and the reaction zone proceeds inward toward the center of the combustion chamber. The second part of this study investigates the charge preparation of the RCCI strategy using planar laser-induced fluorescence (PLIF) of a fuel tracer under non-reacting conditions to quantify fuel concentration distributions prior to ignition. The fuel-tracer PLIF data show that the combustion event proceeds down gradients in the n-heptane distribution. The third part of the study uses chemical kinetics modeling over a range of mixtures spanning the distributions observed from the fuel-tracer fluorescence imaging to isolate the roles of temperature, equivalence ratio, and PRF number stratification. The simulations predict that PRF number stratification is the dominant factor controlling the ignition location and growth rate of the reaction zone. Equivalence ratio has a smaller, but still significant, influence. Lastly, temperature stratification had a negligible influence due to the NTC behavior of the PRF mixtures.

  11. Carbonaceous aerosols recorded in a southeastern Tibetan glacier: analysis of temporal variations and model estimates of sources and radiative forcing

    SciTech Connect (OSTI)

    Wang, Mo; Xu, B.; Cao, J.; Tie, X.; Wang, Hailong; Zhang, Rudong; Qian, Yun; Rasch, Philip J.; Zhao, Shuyu; Wu, Guangjian; Zhao, Huabiao; Joswiak, Daniel R.; Li, Jiule; Xie, Ying

    2015-02-02

    High temporal resolution measurements of black carbon (BC) and organic carbon (OC) covering the time period of 19562006 in an ice core over the southeastern Tibetan Plateau show a distinct seasonal dependence of BC and OC with higher respective concentrations but a lower OC / BC ratio in the non-monsoon season than during the summer monsoon. We use a global aerosol-climate model, in which BC emitted from different source regions can be explicitly tracked, to quantify BC sourcereceptor relationships between four Asian source regions and the southeastern Tibetan Plateau as a receptor. The model results show that South Asia has the largest contribution to the present-day (19962005) mean BC deposition at the ice-core drilling site during the non-monsoon season (October to May) (81%) and all year round (74%), followed by East Asia (14% to the non-monsoon mean and 21% to the annual mean). The ice-core record also indicates stable and relatively low BC and OC deposition fluxes from the late 1950s to 1980, followed by an overall increase to recent years. This trend is consistent with the BC and OC emission inventories and the fuel consumption of South Asia (as the primary contributor to annual mean BC deposition). Moreover, the increasing trend of the OC / BC ratio since the early 1990s indicates a growing contribution of coal combustion and/or biomass burning to the emissions. The estimated radiative forcing induced by BC and OC impurities in snow has increased since 1980, suggesting an increasing potential influence of carbonaceous aerosols on the Tibetan glacier melting and the availability of water resources in the surrounding regions. Our study indicates that more attention to OC is merited because of its non-negligible light absorption and the recent rapid increases evident in the ice-core record.

  12. Examination of utility Phase 1 compliance choices and state reactions to Title IV of the Clean Air Act Amendments of 1990

    SciTech Connect (OSTI)

    Bailey, K.A.; Elliott, T.J.; Carlson, L.J.; South, D.W.

    1993-11-01

    Title IV (acid rain) of the Clean Air Act Amendments of 1990 is imposing new limitations on the emission of sulfur dioxide (SO{sub 2}) and nitrogen oxides (N{sub x}) from electric power plants. The act requires utilities to develop compliance plans to reduce these emissions, and indications are that these plans will dramatically alter traditional operating procedures. A key provision of the SO{sub 2} control program deaned in Title IV is the creation of a system of emission allowances, with utilities having the option of complying by adjusting system emissions and allowance holdings. A compilation of SO{sub 2} compliance activities by the 110 utility plants affected by Phase I is summarized in this report. These compliance plans are presented in a tabular form, correlated with age, capacity, and power pool data. A large number of the Phase I units (46%) have chosen to blend or switch to lower sulfur coals. This choice primarily is in response to (1) prices of low-sulfur coal and (2) the need to maintain SO{sub 2} control flexibility because of uncertain future environmental regulations (e.g., air toxics, carbon dioxide) and compliance prices. The report also discusses the responses of state legislatures and public utility commissions to the compliance requirements in Title IV. Most states have taken negligible action regarding the regulatory treatment of allowances and compliance activities. To protect mine employment, states producing high-sulfur coal have enacted regulations encouraging continued use of that coal, but for the most part, this response has had little effect on utility compliance choices.

  13. Independent Review of Simulation of Net Infiltration for Present-Day and Potential Future Climates

    SciTech Connect (OSTI)

    Review Panel: Soroosh Sorooshian, Ph.D., Panel Chairperson, University of California, Irvine; Jan M. H. Hendrickx, Ph.D., New Mexico Institute of Mining and Technology; Binayak P. Mohanty, Ph.D., Texas A&M University; Scott W. Tyler, Ph.D., University of Nevada, Reno; Tian-Chyi Jim Yeh, Ph.D., University of Arizona -- ORISE Review Facilitators: Robert S. Turner, Ph.D., Technical Review Group Manager, Oak Ridge Institute for Science and Education; Brian R. Herndon, Project Manager, Oak Ridge Institute for Science and Education; Russ Manning, Technical Writer/Editor, Haselwood Enterprises, Inc.

    2008-08-30

    The DOE Office of Civilian Radioactive Waste Management (OCRWM) tasked Oak Ridge Institute for Science and Education (ORISE) with providing an independent expert review of the documented model and prediction results for net infiltration of water into the unsaturated zone at Yucca Mountain. The specific purpose of the model, as documented in the report MDL-NBS-HS-000023, Rev. 01, is “to provide a spatial representation, including epistemic and aleatory uncertainty, of the predicted mean annual net infiltration at the Yucca Mountain site ...” (p. 1-1) The expert review panel assembled by ORISE concluded that the model report does not provide a technically credible spatial representation of net infiltration at Yucca Mountain. Specifically, the ORISE Review Panel found that: • A critical lack of site-specific meteorological, surface, and subsurface information prevents verification of (i) the net infiltration estimates, (ii) the uncertainty estimates of parameters caused by their spatial variability, and (iii) the assumptions used by the modelers (ranges and distributions) for the characterization of parameters. The paucity of site-specific data used by the modeling team for model implementation and validation is a major deficiency in this effort. • The model does not incorporate at least one potentially important hydrologic process. Subsurface lateral flow is not accounted for by the model, and the assumption that the effect of subsurface lateral flow is negligible is not adequately justified. This issue is especially critical for the wetter climate periods. This omission may be one reason the model results appear to underestimate net infiltration beneath wash environments and therefore imprecisely represent the spatial variability of net infiltration. • While the model uses assumptions consistently, such as uniform soil depths and a constant vegetation rooting depth, such assumptions may not be appropriate for this net infiltration simulation because they oversimplify a complex landscape and associated hydrologic processes, especially since the model assumptions have not been adequately corroborated by field and laboratory observations at Yucca Mountain.

  14. CHARACTERIZATION OF TANK 19F SAMPLES

    SciTech Connect (OSTI)

    Oji, L.; Diprete, D.; Click, D.

    2009-12-17

    The Savannah River National Laboratory (SRNL) was asked by Liquid Waste Operations to characterize Tank 19F closure samples. Tank 19F slurry samples analyzed included the liquid and solid fractions derived from the slurry materials along with the floor scrape bottom Tank 19F wet solids. These samples were taken from Tank 19F in April 2009 and made available to SRNL in the same month. Because of limited amounts of solids observed in Tank 19F samples, the samples from the north quadrants of the tank were combined into one Tank 19F North Hemisphere sample and similarly the south quadrant samples were combined into one Tank 19F South Hemisphere sample. These samples were delivered to the SRNL shielded cell. The Tank 19F samples were analyzed for radiological, chemical and elemental components. Where analytical methods yielded additional contaminants other than those requested by the customer, these results were also reported. The target detection limits for isotopes analyzed were based on detection values of 1E-04 {micro}Ci/g for most radionuclides and customer desired detection values of 1E-05 {micro}Ci/g for I-129, Pa-231, Np-237, and Ra-226. While many of the target detection limits, as specified in the technical task request and task technical and quality assurance plans were met for the species characterized for Tank 19F, some were not met. In a number of cases, the relatively high levels of radioactive species of the same element or a chemically similar element precluded the ability to measure some isotopes to low levels. SRNL, in conjunction with the plant customer, reviewed all these cases and determined that the impacts were negligible.

  15. CHARACTERIZATION OF THE TANK 18F SAMPLES

    SciTech Connect (OSTI)

    Oji, L.; Click, D.; Diprete, D.

    2009-12-17

    The Savannah River National Laboratory (SRNL) was asked by Liquid Waste Operations to characterize Tank 18F closure samples. Tank 18F slurry samples analyzed included the liquid and solid fractions derived from the 'as-received' slurry materials along with the floor scrape bottom Tank 18F wet solids. These samples were taken from Tank 18F in March 2009 and made available to SRNL in the same month. Because of limited amounts of solids observed in Tank 18F samples, the samples from the north quadrants of the tank were combined into one North Tank 18F Hemisphere sample and similarly the south quadrant samples were combined into one South Tank 18F Hemisphere sample. These samples were delivered to the SRNL shielded cell. The Tank 18F samples were analyzed for radiological, chemical and elemental components. Where analytical methods yielded additional contaminants other than those requested by the customer, these results were also reported. The target detection limits for isotopes analyzed were 1E-04 {micro}Ci/g for most radionuclides and customer desired detection values of 1E-05 {micro}Ci/g for I-129, Pa-231, Np-237, and Ra-226. While many of the minimum detection limits, as specified in the technical task request and task technical and quality assurance plans were met for the species characterized for Tank 18F, some were not met due to spectral interferences. In a number of cases, the relatively high levels of radioactive species of the same element or a chemically similar element precluded the ability to measure some isotopes to low levels. SRNL, in conjunction with the plant customer, reviewed all these cases and determined that the impacts were negligible.

  16. Stop and Restart Effects on Modern Vehicle Starting System Components

    SciTech Connect (OSTI)

    Windover, Paul R.; Owens, Russell J.; Levinson, Terry M.; Laughlin, Michael; Gaines, Linda

    2015-01-01

    Many drivers of personal and commercial vehicles believe that turning the vehicle off and on frequently instead of idling will cause premature wear of the starter system (starter motor and starter battery). As a result, they are concerned that the replacement cost of the starter motor and/or battery due to increased manual engine cycling would be more than the cumulative cost of the fuel saved by not idling unnecessarily. A number of variables play a role in addressing this complex concern, including the number of starting cycles per day, the time between starting cycles, the intended design life of the starting system, the amount of fuel used to restart an engine, and the cumulative cost of the saved fuel. Qualitative and quantitative information from a variety of sources was used to develop a life-cycle economic model to evaluate the cost and quantify the realistic factors that are related to the permissible frequency of starter motor cycles for the average vehicle to economically minimize engine idle time. Annual cost savings can be calculated depending on shutdown duration and the number of shutdown cycles per day. Analysis shows that cost savings are realized by eliminating idling exceeding one minute by shutting down the engine and restarting it. For a typical motorist, the damage to starting system components resulting from additional daily start cycles will be negligible. Overall, it was found that starter life is mostly dependent on the total number of start cycles, while battery life is more dependent on ensuring a full charge between start events.

  17. Towards eliminating systematic errors caused by the experimental conditions in Biochemical Methane Potential (BMP) tests

    SciTech Connect (OSTI)

    Strmberg, Sten; Nistor, Mihaela; Liu, Jing

    2014-11-15

    Highlights: The evaluated factors introduce significant systematic errors (1038%) in BMP tests. Ambient temperature (T) has the most substantial impact (?10%) at low altitude. Ambient pressure (p) has the most substantial impact (?68%) at high altitude. Continuous monitoring of T and p is not necessary for kinetic calculations. - Abstract: The Biochemical Methane Potential (BMP) test is increasingly recognised as a tool for selecting and pricing biomass material for production of biogas. However, the results for the same substrate often differ between laboratories and much work to standardise such tests is still needed. In the current study, the effects from four environmental factors (i.e. ambient temperature and pressure, water vapour content and initial gas composition of the reactor headspace) on the degradation kinetics and the determined methane potential were evaluated with a 2{sup 4} full factorial design. Four substrates, with different biodegradation profiles, were investigated and the ambient temperature was found to be the most significant contributor to errors in the methane potential. Concerning the kinetics of the process, the environmental factors impact on the calculated rate constants was negligible. The impact of the environmental factors on the kinetic parameters and methane potential from performing a BMP test at different geographical locations around the world was simulated by adjusting the data according to the ambient temperature and pressure of some chosen model sites. The largest effect on the methane potential was registered from tests performed at high altitudes due to a low ambient pressure. The results from this study illustrate the importance of considering the environmental factors influence on volumetric gas measurement in BMP tests. This is essential to achieve trustworthy and standardised results that can be used by researchers and end users from all over the world.

  18. An optical technique for measuring divergence, beam profile, and aiming direction, of relativistic negative hydrogen ions

    SciTech Connect (OSTI)

    Hershcovitch, A.

    1988-02-01

    A novel, nonobstructive diagnostic technique for high energy H/sup minus/D/sup minus/ ion beams is described. This scheme employs spectroscopic techniques designed to measure beam profile, perpendicular velocity spread (i.e., divergence), and orientation of multiMeV H/sup minus/ beams. The basic principle of this method is to photoneutralize a small portion of the H/sup minus/ beam in a way such that the photodetachment process results in the formation of excited hydrogen atoms in the n = 2 levels. Observation of fluorescence from spontaneous decay of H(sp) andor induced deacy of H(2s) can be readily used to determine beam profile. Doppler broadening measurements can be used to determine velocity spread from which beam emittance is calculated. With off-the-shelf instruments resolutions of 1 mm for beam profile and 2 x 10/sup minus/2) ..pi.. cm-mrad are possible. For photodetachment, the best commercially available laser is found to be ArF eximer laser. The analysis is performed for the 200 MEV BNL Linac. The laser, which has a pulse duration which has a pulse duration which is of 10/sup minus/5) of the linac can produce sufficient signal at a negligible beam loss. In addition, measurements of minute Doppler shifts of this Lyman-Alpha radiation by a spectrograph could in principle resolve beam direction to within 1.57 ..mu..rad. The process under consideration has a resonance known as the shape resonance. As the following literature review indicates, the total cross section is known and there is a reasonable agreement between theory and experiment. There are no experimental measurements of partical cross sections. nevertheless, there are theoretical estimates which agree within 15%. 10 refs., 1 fig.

  19. TURBULENCE AND RADIO MINI-HALOS IN THE SLOSHING CORES OF GALAXY CLUSTERS

    SciTech Connect (OSTI)

    ZuHone, J. A.; Markevitch, M.; Giacintucci, S.

    2013-01-10

    A number of relaxed, cool-core galaxy clusters exhibit diffuse, steep-spectrum radio sources in their central regions, known as radio mini-halos. It has been proposed that the relativistic electrons responsible for the emission have been reaccelerated by turbulence generated by the sloshing of the cool core gas. We present a high-resolution MHD simulation of gas sloshing in a galaxy cluster coupled with subgrid simulations of relativistic electron acceleration to test this hypothesis. Our simulation shows that the sloshing motions generate turbulence on the order of {delta}v {approx} 50-200 km s{sup -1} on spatial scales of {approx}50-100 kpc and below in the cool core region within the envelope of the sloshing cold fronts, whereas outside the cold fronts, there is negligible turbulence. This turbulence is potentially strong enough to reaccelerate relativistic electron seeds (with initial {gamma} {approx} 100-500) to {gamma} {approx} 10{sup 4} via damping of magnetosonic waves and non-resonant compression. The seed electrons could remain in the cluster from, e.g., past active galactic nucleus activity. In combination with the magnetic field amplification in the core, these electrons then produce diffuse radio synchrotron emission that is coincident with the region bounded by the sloshing cold fronts, as indeed observed in X-rays and the radio. The result holds for different initial spatial distributions of pre-existing relativistic electrons. The power and the steep spectral index ({alpha} Almost-Equal-To 1-2) of the resulting radio emission are consistent with observations of mini-halos, though the theoretical uncertainties of the acceleration mechanisms are high. We also produce simulated maps of inverse-Compton hard X-ray emission from the same population of relativistic electrons.

  20. SU-E-T-645: Dose Enhancement to Cell Nucleus Due to Hard Collisions of Protons with Electrons in Gold Nanospheres

    SciTech Connect (OSTI)

    Eley, J; Krishnan, S

    2014-06-15

    Purpose: The purpose of this study was to investigate the theoretical dose enhancement to a cell nucleus due to increased fluence of secondary electrons when gold nanospheres are present in the cytoplasm during proton therapy. Methods: We modeled the irradiation of prostate cancer cells using protons of variable energies when 10,000 gold nanoparticles, each with radius of 10 nm, were randomly distributed in the cytoplasm. Using simple analytical equations, we calculated the increased mean dose to the cell nucleus due to secondary electrons produced by hard collisions of 0.1, 1, 10, and 100 MeV protons with orbital electrons in gold. We only counted electrons with kinetic energy higher than 1 keV. In addition to calculating the increase in the mean dose to the cell nucleus, we also calculated the increase in local dose in the shadow, i.e., the umbra, of individual gold nanospheres due to forward scattered electrons. Results: For proton energies of 0.1, 1, 10, and 100 MeV, we calculated increases to the mean nuclear dose of 0.15, 0.09, 0.05, and 0.04%, respectively. When we considered local dose increases in the shadows of individual gold spheres, we calculated local dose increases of 5.5, 3.2, 1.9, and 1.3%, respectively. Conclusion: We found negligible, less than 0.2%, increases in the mean dose to the cell nucleus due to electrons produced by hard collisions of protons with electrons in gold nanospheres. However, we observed increases up to 5.5% in the local dose in the shadow of gold nanospheres. Considering the shadow radius of 10 nm, these local dose enhancements may have implications for slightly increased probability of clustered DNA damage when gold nanoparticles are close to the nuclear membrane.

  1. High-resolution dynamically downscaled projections of precipitation in the mid and late 21st century over North America

    SciTech Connect (OSTI)

    none,

    2015-07-29

    This study performs high-spatial-resolution (12 km) Weather Research and Forecasting (WRF) simulations over a very large domain (7200 km 6180 km, covering much of North America) to explore changes in mean and extreme precipitation in the mid and late 21st century under Representative Concentration Pathways 4.5 (RCP 4.5) and 8.5 (RCP 8.5). We evaluate WRF model performance for a historical simulation and future projections, applying the Community Climate System Model version 4 (CCSM4) as initial and boundary conditions with and without a bias correction. WRF simulations using boundary and initial conditions from both versions of CCSM4 show smaller biases versus evaluation data sets than does CCSM4 over western North America. WRF simulations also improve spatial details of precipitation over much of North America. However, driving the WRF with the bias-corrected CCSM4 does not always reduce the bias. WRF-projected changes in precipitation include decreasing intensity over the southwestern United States, increasing intensity over the eastern United States and most of Canada, and an increase in the number of days with heavy precipitation over much of North America. Projected precipitation changes are more evident in the late 21st century than the mid 21st century, and they are more evident under RCP 8.5 than under RCP 4.5 in the late 21st century. Uncertainties in the projected changes in precipitation due to different warming scenarios are non-negligible. Differences in summer precipitation changes between WRF and CCSM4 are significant over most of the United States.

  2. Importance of Diffusion in Methanol Photochemistry on TiO2(110)

    SciTech Connect (OSTI)

    Shen, Mingmin; Acharya, Danda P.; Dohnalek, Zdenek; Henderson, Michael A.

    2012-12-06

    The photoactivity of methanol on the rutile TiO2(110) surface is shown to depend on the ability of methanol to diffuse on the surface and find sites active for its thermal dissociation to methoxy. Temperature programmed desorption (TPD) results show that the extent of methanol photodecomposition to formaldehyde is negligible on the clean TiO2(110) surface at 100 K due to a scarcity of sites that can convert (photoinactive) methanol to (photoactive) methoxy. The extent of photoactivity at 100 K significantly increases when methanol is coadsorbed with oxygen, however only those molecules able to adsorb near (next to) a coadsorbed oxygen species are active. Preannealing coadsorbed methanol and oxygen to above 200 K prior to UV irradiation results in a significant increase in photoactivity. Scanning tunneling microscopy (STM) images clearly show that the advent of increased photoactivity in TPD correlates with the onset of methanol diffusion along the surfaces Ti4+ rows at ~200 K. These results demonstrate that optimizing thermal processes (such as diffusion or proton transfer reactions) can be critical to maximizing photocatalytic reactivity on TiO2 surfaces. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle under contract DEAC05-76RL01830. The research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  3. Land application uses for dry FGD by-products. Phase 2 report

    SciTech Connect (OSTI)

    Stehouwer, R.; Dick, W.; Bigham, J.

    1996-03-01

    A study was initiated in December 1990 to demonstrate large volume beneficial uses of flue gas desulfurization (FGD) by-products. A Phase 1 report provided results of an extensive characterization of chemical, physical, mineralogical and engineering properties of 58 dry FGD by-product samples. The Phase 1 report concluded that high volume beneficial reuses will depend on the economics related to their ability to substitute for existing materials for various types of applications (e.g. as an agricultural liming material, soil borrow for highway embankment construction, and reclamation of active and abandoned surface coal mine lands). Phase 2 objectives were (1) to conduct laboratory and greenhouse studies of FGD and soil (spoil) mixtures for agronomic and engineering applications, (2) to initiate field studies related to high volume agronomic and engineering uses, and (3) to develop the basic methodological framework for estimation of the financial and economic costs and benefits to society of several FGD reuse options and to make some preliminary runs of economic models. High volume beneficial reuses of dry FGD by-products have been successfully demonstrated. Adverse environmental impacts have been negligible. Although few sources of dry FGD by-products currently exist in Ohio and the United States there is potential for smaller coal-fired facilities to adopt S0{sub 2} scrubbing technologies that produce dry FGD material. Also much of what we have learned from studies on dry FGD by-products is applicable to the more prevalent wet FGD by-products. The adaptation of the technologies demonstrated in this project seem to be not only limited by economic constraints, but even more so, by the need to create awareness of the market potential of using these FGD by-products.

  4. Next Generation Solvent Performance in the Modular Caustic Side Solvent Extraction Process - 15495

    SciTech Connect (OSTI)

    Smith, Tara E.; Scherman, Carl; Martin, David; Suggs, Patricia

    2015-01-14

    Changes to the Modular Caustic Side Solvent Extraction Unit (MCU) flow-sheet were implemented in the facility. Implementation included changing the scrub and strip chemicals and concentrations, modifying the O/A ratios for the strip, scrub, and extraction contactor banks, and blending the current BoBCalixC6 extractant-based solvent in MCU with clean MaxCalix extractant-based solvent. During the successful demonstration period, the MCU process was subject to rigorous oversight to ensure hydraulic stability and chemical/radionuclide analysis of the key process tanks (caustic wash tank, solvent hold tank, strip effluent hold tank, and decontaminated salt solution hold tank) to evaluate solvent carryover to downstream facilities and the effectiveness of cesium removal from the liquid salt waste. Results indicated the extraction of cesium was significantly more effective with an average Decontamination Factor (DF) of 1,129 (range was 107 to 1,824) and that stripping was effective. The contactor hydraulic performance was stable and satisfactory, as indicated by contactor vibration, contactor rotational speed, and flow stability; all of which remained at or near target values. Furthermore, the Solvent Hold Tank (SHT) level and specific gravity was as expected, indicating that solvent integrity and organic hydraulic stability were maintained. The coalescer performances were in the range of processing results under the BOBCalixC6 flow sheet, indicating negligible adverse impact of NGS deployment. After the Demonstration period, MCU began processing via routine operations. Results to date reiterate the enhanced cesium extraction and stripping capability of the Next Generation Solvent (NGS) flow sheet. This paper presents process performance results of the NGS Demonstration and continued operations of MCU utilizing the blended BobCalixC6-MaxCalix solvent under the NGS flowsheet.

  5. Separation of Plutonium from Irradiated Fuels and Targets

    SciTech Connect (OSTI)

    Gray, Leonard W.; Holliday, Kiel S.; Murray, Alice; Thompson, Major; Thorp, Donald T.; Yarbro, Stephen; Venetz, Theodore J.

    2015-09-30

    The production of electricity by nuclear fission is, at present, nearly 366- gigawatt electric (GWe), generated from 438 operating nuclear reactors. Unlike fossil fuel ash, with limited residual available energy content and negligible heat content, the spent nuclear fuel from power production reactors contains moderate amounts of transuranium (TRU) actinides and fission products in addition to the still slightly enriched uranium. Originally nuclear technology was developed to chemically separate and recover fissionable plutonium from irradiated nuclear fuel for military purposes. Military plutonium separations had essentially ceased by the mid-1990s. Reprocessing, however, can serve multiple purposes and the relative importance has changed over time. In the 1960’s the vision of the introduction of plutonium-fueled fast-neutron breeder reactors drove the civilian separation of plutonium. More recently, reprocessing has been regarded as a means to facilitate the disposal of high-level nuclear waste and thus requires development of radically different technical approaches. In the last decade or so, principal reason for reprocessing has shifted to spent power reactor fuel being reprocessed 1) so that unused uranium and plutonium being recycled reduce the volume, gaining some 25% to 30% more energy from the original uranium in the process and thus contributing to energy security and 2) reduce the volume and radioactivity of the waste by recovering all long-lived actinides and fission products followed by recycling them in fast reactors where they are transmuted to short-lived fission products; this reduces the volume to about 20%, reduces the long term radioactivity level in the high-level waste, and complicates the possibility of the plutonium being diverted from civil use – thereby increasing the proliferation resistance of the fuel cycle.

  6. Electrostatic contribution from solvent in modulating single-walled carbon nanotube association

    SciTech Connect (OSTI)

    Ou, Shu-Ching; Patel, Sandeep

    2014-09-21

    We perform all-atom molecular dynamics simulations to compute the potential of mean force (PMF) between two (10,10) single-walled carbon nanotubes solvated in pure nonpolarizable SPC/E and polarizable TIP4P-FQ water, at various temperatures. In general, the reversible work required to bring two nanotubes from a dissociated state (free energy reference) to contact state (free energy minimum) is more favorable and less temperature-dependent in TIP4P-FQ than in SPC/E water models. In contrast, molecular properties and behavior of water such as the spatially-resolved water number density (intertube, intratube, or outer regions), for TIP4P-FQ are more sensitive to temperature than SPC/E. Decomposition of the solvent-induced PMF into different spatial regions suggests that TIP4P-FQ has stronger temperature dependence; the opposing destabilizing/stabilizing contributions from intertube water and more distal water balance each other and suppress the temperature dependence of total association free energy. Further investigation of hydrogen bonding network in intertube water reveals that TIP4P-FQ retains fewer hydrogen bonds than SPC/E, which correlates with the lower water number density in this region. This reduction of hydrogen bonds affects the intertube water dipoles. As the intertube volume decreases, TIP4P-FQ dipole moment approaches the gas phase value; the distribution of dipole magnitude also becomes narrower due to less average polarization/perturbation from other water molecules. Our results imply that the reduction of water under confinement may seem trivial, but underlying effects to structure and free energetics are non-negligible.

  7. Laplace plane modifications arising from solar radiation pressure

    SciTech Connect (OSTI)

    Rosengren, Aaron J.; Scheeres, Daniel J.

    2014-05-01

    The dynamical effects of solar radiation pressure (SRP) in the solar system have been rigorously studied since the early 1900s. This non-gravitational perturbation plays a significant role in the evolution of dust particles in circumplanetary orbits, as well as in the orbital motion about asteroids and comets. For gravitationally dominated orbits, SRP is negligible and the resulting motion is largely governed by the oblateness of the primary and the attraction of the Sun. The interplay between these gravitational perturbations gives rise to three mutually perpendicular planes of equilibrium for circular satellite orbits. The classical Laplace plane lies between the equatorial and orbital planes of the primary, and is the mean reference plane about whose axis the pole of a satellite's orbit precesses. From a previously derived solution for the secular motion of an orbiter about a small body in a SRP dominated environment, we find that SRP acting alone will cause an initially circular orbit to precess around the pole of the primary's heliocentric orbital plane. When the gravitational and non-gravitational perturbations act in concert, the resulting equilibrium planes turn out to be qualitatively different, in some cases, from those obtained without considering the radiation pressure. The warping of the surfaces swept out by the modified equilibria as the semi-major axis varies depends critically on the cross-sectional area of the body exposed. These results, together with an adiabatic invariance argument on Poynting-Robertson drag, provide a natural qualitative explanation for the initial albedo dichotomy of Saturn's moon, Iapetus.

  8. Portal Vein Embolization with Radiolabeled Polyvinyl Alcohol Particles in a Swine Model: Hepatic Distribution and Implications for Pancreatic Islet Cell Transplantation

    SciTech Connect (OSTI)

    Owen, Richard J.; Mercer, John R.; Al-Saif, Faisal; Molinari, Michele; Ashforth, Robert A.; Rajotte, Ray V.; Conner-Spady, Barbara; Shapiro, A. M. James

    2009-05-15

    The distribution of radiolabeled polyvinyl alcohol microspheres (PVAMs) when infused into the portal vein of domestic swine was investigated, with the purpose of assessing implications for pancreatic islet cell transplantation. PVAMs measuring 100-300 {mu}m (Contour SE) and labeled with {sup 99m}Tc were infused into the main portal vein of 12 swine, with intermittent portal venous pressure measurements. The infusion catheter was introduced antegradely via direct or indirect cannulation of the portal vein. The liver was subsequently divided into anatomical segments. Radioactivity (decay corrected) was measured for {sup 99m}Tc microsphere synthesis, dose preparation, gross organ activities, tissue samples, and blood. Particulate labeling, catheter positioning, and infusion were successful in all cases. The number of particles used was (185,000 {+-} 24,000) with a volume of 1 ml. Mean portal pressure at 5 min was significantly higher than baseline, but without a significant difference at 15 min. Extrahepatic tissue and serum radioactivity was negligible. A significant difference in number of radioactive particles per gram was detected between segments 6/7 and segments 5/8. Intrasegmental activity was analyzed, and for segments 2/3 a significant difference in the percentage dose per gram across samples was demonstrated (P = 0.001). Effective and stable radiolabeling of PVAMs with {sup 99m}Tc-sulfur colloid was demonstrated. Portal venous infusion of 100- to 300-{mu}m particles showed entrapment in the sinusoidal hepatic system with transient portal pressure elevation. Preferential embolization into the right lateral and posterior segments occurs, suggesting that flow dynamics/catheter tip position plays a role in particle distribution.

  9. IMAGING THE EPOCH OF REIONIZATION: LIMITATIONS FROM FOREGROUND CONFUSION AND IMAGING ALGORITHMS

    SciTech Connect (OSTI)

    Vedantham, Harish; Udaya Shankar, N.; Subrahmanyan, Ravi

    2012-02-01

    Tomography of redshifted 21 cm transition from neutral hydrogen using Fourier synthesis telescopes is a promising tool to study the Epoch of Reionization (EoR). Limiting the confusion from Galactic and extragalactic foregrounds is critical to the success of these telescopes. The instrumental response or the point-spread function (PSF) of such telescopes is inherently three dimensional with frequency mapping to the line-of-sight (LOS) distance. EoR signals will necessarily have to be detected in data where continuum confusion persists; therefore, it is important that the PSF has acceptable frequency structure so that the residual foreground does not confuse the EoR signature. This paper aims to understand the three-dimensional PSF and foreground contamination in the same framework. We develop a formalism to estimate the foreground contamination along frequency, or equivalently LOS dimension, and establish a relationship between foreground contamination in the image plane and visibility weights on the Fourier plane. We identify two dominant sources of LOS foreground contamination-'PSF contamination' and 'gridding contamination'. We show that PSF contamination is localized in LOS wavenumber space, beyond which there potentially exists an 'EoR window' with negligible foreground contamination where we may focus our efforts to detect EoR. PSF contamination in this window may be substantially reduced by judicious choice of a frequency window function. Gridding and imaging algorithms create additional gridding contamination and we propose a new imaging algorithm using the Chirp Z Transform that significantly reduces this contamination. Finally, we demonstrate the analytical relationships and the merit of the new imaging algorithm for the case of imaging with the Murchison Widefield Array.

  10. On the significance of power asymmetries in Planck CMB data at all scales

    SciTech Connect (OSTI)

    Quartin, Miguel [Instituto de Fsica, Universidade Federal do Rio de Janeiro, 21941-972, Rio de Janeiro, RJ (Brazil); Notari, Alessio, E-mail: mquartin@if.ufrj.br, E-mail: notari@ffn.ub.es [Departament de Fsica Fondamental i Institut de Cincies del Cosmos, Universitat de Barcelona, Mart i Franqus 1, E-08028 Barcelona (Spain)

    2015-01-01

    We perform an analysis of the CMB temperature data taken by the Planck satellite investigating if there is any significant deviation from cosmological isotropy. We look for differences in the spectrum between two opposite hemispheres and also for dipolar modulations. We propose a new way to avoid biases due to partial-sky coverage by producing a mask symmetrized in antipodal directions, in addition to the standard smoothing procedure. We also properly take into account both Doppler and aberration effects due to our peculiar velocity and the anisotropy of the noise, since these effects induce a significant hemispherical asymmetry. We are thus able to probe scales all the way to ?=2000. After such treatment we find no evidence for significant hemispherical anomalies along any of the analyzed directions (i.e. deviations are less than 1.5? when summing over all scales). Although among the larger scales there are sometimes higher discrepancies, these are always less than 3?. We also find results on a dipolar modulation of the power spectrum. Along the hemispheres aligned with the most asymmetric direction for 2???2000 we find a 3.3? discrepancy when comparing to simulations. However, if we do not restrict ourselves to Planck's maximal asymmetry axis, which can only be known a posteriori, and compare Planck data with the modulation of simulations along their respective maximal asymmetry directions, the discrepancy goes down to less than 1? (with, again, almost 3? discrepancies in some low-? modes). We thus conclude that no significant power asymmetries seem to be present in the full data set. Interestingly, without proper removal of Doppler and aberration effects one would find spurious anomalies at high ?, between 3? and 5?. Even when considering only ?<600 we find that the boost is non-negligible and alleviates the discrepancy by roughly half-?.

  11. PS1-10jh: The disruption of a main-sequence star of near-solar composition

    SciTech Connect (OSTI)

    Guillochon, James; Manukian, Haik; Ramirez-Ruiz, Enrico

    2014-03-01

    When a star comes within a critical distance to a supermassive black hole (SMBH), immense tidal forces disrupt the star, resulting in a stream of debris that falls back onto the SMBH and powers a luminous flare. In this paper, we perform hydrodynamical simulations of the disruption of a main-sequence star by an SMBH to characterize the evolution of the debris stream after a tidal disruption. We demonstrate that this debris stream is confined by self-gravity in the two directions perpendicular to the original direction of the star's travel and as a consequence has a negligible surface area and makes almost no contribution to either the continuum or line emission. We therefore propose that any observed emission lines are not the result of photoionization in this unbound debris, but are produced in the region above and below the forming elliptical accretion disk, analogous to the broad-line region (BLR) in steadily accreting active galactic nuclei. As each line within a BLR is observationally linked to a particular location in the accretion disk, we suggest that the absence of a line indicates that the accretion disk does not yet extend to the distance required to produce that line. This model can be used to understand the spectral properties of the tidal disruption event PS1-10jh, for which He II lines are observed, but the Balmer series and He I are not. Using a maximum likelihood analysis, we show that the disruption of a main-sequence star of near-solar composition can reproduce this event.

  12. OZSPEC-2: An improved broadband high-resolution elliptical crystal x-ray spectrometer for high-energy density physics experiments (invited)

    SciTech Connect (OSTI)

    Heeter, R. F.; Anderson, S. G.; Booth, R.; Brown, G. V.; Emig, J.; Fulkerson, S.; McCarville, T.; Norman, D.; Schneider, M. B.; Young, B. K. F.

    2008-10-15

    A novel time, space, and energy-resolved x-ray spectrometer has been developed which produces, in a single snapshot, a broadband and relatively calibrated spectrum of the x-ray emission from a high-energy density laboratory plasma. The opacity zipper spectrometer (OZSPEC-1) records a nearly continuous spectrum for x-ray energies from 240 to 5800 eV in a single shot. The second-generation OZSPEC-2, detailed in this work, records fully continuous spectra on a single shot from any two of these three bands: 270-650, 660-1580, and 1960-4720 eV. These instruments thus record thermal and line radiation from a wide range of plasmas. These instruments' single-shot bandwidth is unmatched in a time-gated spectrometer; conversely, other broadband instruments are either time-integrated (using crystals or gratings), lack spectral resolution (diode arrays), or cover a lower energy band (gratings). The OZSPECs are based on the zipper detector, a large-format (100x35 mm) gated microchannel plate detector, with spectra dispersed along the 100 mm dimension. OZSPEC-1 and -2 both use elliptically bent crystals of OHM, RAP, and/or PET. Individual spectra are gated in 100 ps. OZSPEC-2 provides one-dimensional spatial imaging with 30-50 {mu}m resolution over a 1500 {mu}m field of view at the source. The elliptical crystal design yields broad spectral coverage with resolution E/{delta}E>500, strong rejection of hard x-ray backgrounds, and negligible source broadening for extended sources. Near-term applications include plasma opacity measurements, detailed spectra of inertial fusion Hohlraums, and laboratory astrophysics experiments.

  13. Reactions of the CN Radical with Benzene and Toluene: Product Detection and Low-Temperature Kinetics

    SciTech Connect (OSTI)

    Trevitt, Adam J.; Goulay, Fabien; Taatjes, Craig A.; Osborn, David L.; Leone, Stephen R.

    2009-12-23

    Low temperature rate coefficients are measured for the CN + benzene and CN + toluene reactions using the pulsed Laval nozzle expansion technique coupled with laser-induced fluorescence detection. The CN + benzene reaction rate coefficient at 105, 165 and 295 K is found to be relatively constant over this temperature range, 3.9 - 4.9 x 10-10 cm3 molecule-1 s-1. These rapid kinetics, along with the observed negligible temperature dependence, are consistent with a barrierless reaction entrance channel and reaction efficiencies approaching unity. The CN + toluene reaction is measured to have a slower rate coefficient of 1.3 x 10-10 cm3 molecule-1 s-1 at 105 K. At room temperature, non-exponential decay profiles are observed for this reaction that may suggest significant back-dissociation of intermediate complexes. In separate experiments, the products of these reactions are probed at room temperature using synchrotron VUV photoionization mass spectrometry. For CN + benzene, cyanobenzene (C6H5CN) is the only product recorded with no detectable evidence for a C6H5 + HCN product channel. In the case of CN + toluene, cyanotoluene (NCC6H4CH3) constitutes the only detected product. It is not possible to differentiate among the ortho, meta and para isomers of cyanotoluene because of their similar ionization energies and the ~;; 40 meV photon energy resolution of the experiment. There is no significant detection of benzyl radicals (C6H5CH2) that would suggest a H-abstraction or a HCN elimination channel is prominent at these conditions. As both reactions are measured to be rapid at 105 K, appearing to have barrierless entrance channels, it follows that they will proceed efficiently at the temperatures of Saturn?s moon Titan (~;;100 K) and are also likely to proceed at the temperature of interstellar clouds (10-20 K).

  14. Maintenance and operation procedure, and feedback controls of the J-PARC RF-driven H{sup ?} ion source

    SciTech Connect (OSTI)

    Ueno, A. Ohkoshi, K.; Ikegami, K.; Takagi, A.; Yamazaki, S.; Oguri, H.

    2015-04-08

    In order to satisfy the Japan Proton Accelerator Research Complex (J-PARC) second stage requirements of an H{sup ?} ion beam of 60mA within normalized emittances of 1.5?mmmrad both horizontally and vertically, a flat top beam duty factor of 1.25% (500?s25Hz) and a life-time of longer than 1month, the J-PARC cesiated RF-driven H{sup ?} ion source was developed by using an internal-antenna developed at the Spallation Neutron Source (SNS). The maintenance and operation procedure to minimize the plasma chamber (PCH) replacement time on the beam line, which is very important to maximize the J-PARC beam time especially for an antenna failure, is presented in this paper. The PCH preserved by filling argon (Ar) gas inside after pre-conditioning including pre-cesiation to produce the required beam at a test-stand successfully produced the required beam on the beam line with slight addition of cesium (Cs). The methods of the feedback controls of a 2MHz-RF-matching, an H{sup ?} ion beam intensity and the addition of Cs are also presented. The RF-matching feedback by using two vacuum variable capacitors (VVCs) and RF-frequency shift produced the almost perfect matching with negligibly small reflected RF-power. The H{sup ?} ion beam intensity was controlled within errors of 0.1mA by the RF-power feedback. The amount of Cs was also controlled by remotely opening a Cs-valve to keep the RF-power lower than a settled value.

  15. METHANE IN THE ATMOSPHERE OF THE TRANSITING HOT NEPTUNE GJ436B?

    SciTech Connect (OSTI)

    Beaulieu, J.-P.; Batista, V.; Tinetti, G.; Kipping, D. M.; Barber, R. J.; Tennyson, J.; Waldmann, I.; Miller, S.; Fossey, S. J.; Aylward, A.; Ribas, I.; Cho, J. Y.-K.; Polichtchouk, I.; Yurchenko, S. N.; Griffith, C. A.; Carey, S.; Mousis, O.

    2011-04-10

    We present an analysis of seven primary transit observations of the hot Neptune GJ436b at 3.6, 4.5, and 8 {mu}m obtained with the Infrared Array Camera on the Spitzer Space Telescope. After correcting for systematic effects, we fitted the light curves using the Markov Chain Monte Carlo technique. Combining these new data with the EPOXI, Hubble Space Telescope, and ground-based V, I, H, and K{sub s} published observations, the range 0.5-10 {mu}m can be covered. Due to the low level of activity of GJ436, the effect of starspots on the combination of transits at different epochs is negligible at the accuracy of the data set. Representative climate models were calculated by using a three-dimensional, pseudospectral general circulation model with idealized thermal forcing. Simulated transit spectra of GJ436b were generated using line-by-line radiative transfer models including the opacities of the molecular species expected to be present in such a planetary atmosphere. A new, ab-initio-calculated, line list for hot ammonia has been used for the first time. The photometric data observed at multiple wavelengths can be interpreted with methane being the dominant absorption after molecular hydrogen, possibly with minor contributions from ammonia, water, and other molecules. No clear evidence of carbon monoxide and carbon dioxide is found from transit photometry. We discuss this result in the light of a recent paper where photochemical disequilibrium is hypothesized to interpret secondary transit photometric data. We show that the emission photometric data are not incompatible with the presence of abundant methane, but further spectroscopic data are desirable to confirm this scenario.

  16. How does pressure gravitate? Cosmological constant problem confronts observational cosmology

    SciTech Connect (OSTI)

    Narimani, Ali; Scott, Douglas; Afshordi, Niayesh E-mail: nafshordi@pitp.ca

    2014-08-01

    An important and long-standing puzzle in the history of modern physics is the gross inconsistency between theoretical expectations and cosmological observations of the vacuum energy density, by at least 60 orders of magnitude, otherwise known as the cosmological constant problem. A characteristic feature of vacuum energy is that it has a pressure with the same amplitude, but opposite sign to its energy density, while all the precision tests of General Relativity are either in vacuum, or for media with negligible pressure. Therefore, one may wonder whether an anomalous coupling to pressure might be responsible for decoupling vacuum from gravity. We test this possibility in the context of the Gravitational Aether proposal, using current cosmological observations, which probe the gravity of relativistic pressure in the radiation era. Interestingly, we find that the best fit for anomalous pressure coupling is about half-way between General Relativity (GR), and Gravitational Aether (GA), if we include Planck together with WMAP and BICEP2 polarization cosmic microwave background (CMB) observations. Taken at face value, this data combination excludes both GR and GA at around the 3? level. However, including higher resolution CMB observations (''highL'') or baryonic acoustic oscillations (BAO) pushes the best fit closer to GR, excluding the Gravitational Aether solution to the cosmological constant problem at the 4- 5? level. This constraint effectively places a limit on the anomalous coupling to pressure in the parametrized post-Newtonian (PPN) expansion, ?{sub 4}=0.1050.049 (+highL CMB), or ?{sub 4}=0.0660.039 (+BAO). These represent the most precise measurement of this parameter to date, indicating a mild tension with GR (for ?CDM including tensors, with 0?{sub 4}=), and also among different data sets.

  17. Measurement of emission fluxes from Technical Area 54, Area G and L. Final report

    SciTech Connect (OSTI)

    Eklund, B.

    1995-03-15

    The emission flux (mass/time-area) of tritiated water from TA-54 was measured to support the characterization of radioactive air emissions from waste sites for the Radioactive Air Emissions Management (RAEM) program and for the Area G Performance Assessment. Measurements were made at over 180 locations during the summers of 1993 and 1994, including randomly selected locations across Area G, three suspected areas of contamination at Area G, and the property surrounding TA-54. The emission fluxes of radon were measured at six locations and volatile organic compounds (VOCs) at 30 locations. Monitoring was performed at each location over a several-hour period using the U.S. EPA flux chamber approach. Separate samples for tritiated water, radon, and VOCs were collected and analyzed in off-site laboratories. The measured tritiated water emission fluxes varied over several orders of magnitude, from background levels of about 3 pCi/m{sup 2}-min to 9.69 x 10{sup 6} pCi/m{sup 2}-min near a disposal shaft. Low levels of tritiated water were found to have migrated into Pajarito Canyon, directly south of Area G. The tritium flux data were used to generate an estimated annual emission rate of 14 Curies/yr for all of Area G, with the majority of this activity being emitted from relatively small areas adjacent to several disposal shafts. The estimated total annual release is less than 1% of the total tritium release from all LANL in 1992 and results in a negligible off-site dose. Based on the limited data available, the average emission flux of radon from Area G is estimated to be 8.1 pCi/m{sup 2}-min. The measured emission fluxes of VOCs were < 100 {mu}g/m{sup 2}-min, which is small compared with fluxes typically measured at hazardous waste landfills. The air quality impacts of these releases were evaluated in a separate report.

  18. Measured and predicted temperature profiles along MEMS bridges at pressures from 0.05 to 625 torr.

    SciTech Connect (OSTI)

    Gallis, Michail A.; Torczynski, John Robert; Piekos, Edward Stanley; Serrano, Justin Raymond; Gorby, Allen D.; Phinney, Leslie Mary

    2010-10-01

    We will present experimental and computational investigations of the thermal performance of microelectromechanical systems (MEMS) as a function of the surrounding gas pressure. Lowering the pressure in MEMS packages reduces gas damping, providing increased sensitivity for certain MEMS sensors; however, such packaging also dramatically affects their thermal performance since energy transfer to the environment is substantially reduced. High-spatial-resolution Raman thermometry was used to measure the temperature profiles on electrically heated, polycrystalline silicon bridges that are nominally 10 microns wide, 2.25 microns thick, 12 microns above the substrate, and either 200 or 400 microns long in nitrogen atmospheres with pressures ranging from 0.05 to 625 Torr. Finite element modeling of the thermal behavior of the MEMS bridges is performed and compared to the experimental results. Noncontinuum gas effects are incorporated into the continuum finite element model by imposing temperature discontinuities at gas-solid interfaces that are determined from noncontinuum simulations. The experimental and simulation results indicate that at pressures below 0.5 Torr the gas-phase heat transfer is negligible compared to heat conduction through the thermal actuator legs. As the pressure increases above 0.5 Torr, the gas-phase heat transfer becomes more significant. At ambient pressures, gas-phase heat transfer drastically impacts the thermal performance. The measured and simulated temperature profiles are in qualitative agreement in the present study. Quantitative agreement between experimental and simulated temperature profiles requires accurate knowledge of temperature-dependent thermophysical properties, the device geometry, and the thermal accommodation coefficient.

  19. Systematic characterization of degas-driven flow for poly(dimethylsiloxane) microfluidic devices

    SciTech Connect (OSTI)

    Liang, David Y. [Univ. of California, Berkeley, CA (United States) Biomolecular Nanotechnology Center, Berkeley Sensor and Actuator Center; Tentori, Augusto M. [Univ. of California, Berkeley, CA (United States) Biomolecular Nanotechnology Center, Berkeley Sensor and Actuator Center; Dimov, Ivan K. [Univ. of California, Berkeley, CA (United States) Biomolecular Nanotechnology Center, Berkeley Sensor and Actuator Center; Univ. de Valapariso, Valapariso (Chile); Lee, Luke P. [Univ. of California, Berkeley, CA (United States) Biomolecular Nanotechnology Center, Berkeley Sensor and Actuator Center

    2011-01-01

    Degas-driven flow is a novel phenomenon used to propel fluids in poly(dimethylsiloxane) (PDMS)-based microfluidic devices without requiring any external power. This method takes advantage of the inherently high porosity and air solubility of PDMS by removing air molecules from the bulk PDMS before initiating the flow. The dynamics of degas-driven flow are dependent on the channel and device geometries and are highly sensitive to temporal parameters. These dependencies have not been fully characterized, hindering broad use of degas-driven flow as a microfluidic pumping mechanism. Here, we characterize, for the first time, the effect of various parameters on the dynamics of degas-driven flow, including channel geometry, PDMS thickness, PDMS exposure area, vacuum degassing time, and idle time at atmospheric pressure before loading. We investigate the effect of these parameters on flow velocity as well as channel fill time for the degas-driven flow process. Using our devices, we achieved reproducible flow with a standard deviation of less than 8% for flow velocity, as well as maximum flow rates of up to 3 nL/s and mean flow rates of approximately 1-1.5 nL/s. Parameters such as channel surface area and PDMS chip exposure area were found to have negligible impact on degas-driven flow dynamics, whereas channel cross-sectional area, degas time, PDMS thickness, and idle time were found to have a larger impact. In addition, we develop a physical model that can predict mean flow velocities within 6% of experimental values and can be used as a tool for future design of PDMS-based microfluidic devices that utilize degas-driven flow.

  20. Expression, purification, characterization and crystallization of non- and phosphorylated states of JAK2 and JAK3 kinase domain

    SciTech Connect (OSTI)

    Hall, Troii; Emmons, Thomas L.; Chrencik, Jill E.; Gormley, Jennifer A.; Weinberg, Robin A.; Leone, Joseph W.; Hirsch, Jeffrey L.; Saabye, Matthew J.; Schindler, John F.; Day, Jacqueline E.; Williams, Jennifer M.; Kiefer, James R.; Lightle, Sandra A.; Harris, Melissa S.; Guru, Siradanahalli; Fischer, H. David; Tomasselli, Alfredo G. (Pfizer)

    2012-05-29

    Janus-associated kinases (JAKs) play critical roles in cytokine signaling, and have emerged as viable therapeutic targets in inflammation and oncology related diseases. To date, targeting JAK proteins with highly selective inhibitor compounds have remained elusive. We have expressed the active kinase domains for both JAK2 and JAK3 and devised purification protocols to resolve the non-, mono- (Y1007) and diphosphorylated (Y1007 and Y1008) states of JAK2 and non- and monophosphorylated states of JAK3 (Y980). An optimal purified protein yield of 20, 29 and 69 mg per 20 L cell culture was obtained for the three JAK2 forms, respectively, and 12.2 and 2.3 mg per 10 L fermentation for the two JAK3 forms allowing detailed biochemical and biophysical studies. To monitor the purification process we developed a novel HPLC activity assay where a sequential order of phosphorylation was observed whereby the first tyrosine residue was completely phosphorylated prior to phosphorylation of the tandem tyrosine residue. A Caliper-based microfluidics assay was used to determine the kinetic parameters (K{sub m} and k{sub cat}) for each phosphorylated state, showing that monophosphorylated (Y1007) JAK2 enzyme activity increased 9-fold over that of the nonphosphorylated species, and increased an additional 6-fold for the diphosphorylated (Y1007/Y1008) species, while phosphorylation of JAK3 resulted in a negligible increase in activity. Moreover, crystal structures have been generated for each isolated state of JAK2 and JAK3 with resolutions better than 2.4 {angstrom}. The generation of these reagents has enabled kinetic and structural characterization to inform the design of potent and selective inhibitors of the JAK family.

  1. DIVERSITY OF SHORT GAMMA-RAY BURST AFTERGLOWS FROM COMPACT BINARY MERGERS HOSTING PULSARS

    SciTech Connect (OSTI)

    Holcomb, Cole; Ramirez-Ruiz, Enrico; De Colle, Fabio; Montes, Gabriela [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

    2014-07-20

    Short-duration gamma-ray bursts (sGRBs) are widely believed to result from the mergers of compact binaries. This model predicts an afterglow that bears the characteristic signatures of a constant, low-density medium, including a smooth prompt-afterglow transition, and a simple temporal evolution. However, these expectations are in conflict with observations for a non-negligible fraction of sGRB afterglows. In particular, the onset of the afterglow phase for some of these events appears to be delayed and, in addition, a few of them exhibit late-time rapid fading in their light curves. We show that these peculiar observations can be explained independently of ongoing central engine activity if some sGRB progenitors are compact binaries hosting at least one pulsar. The Poynting flux emanating from the pulsar companion can excavate a bow-shock cavity surrounding the binary. If this cavity is larger than the shock deceleration length scale in the undisturbed interstellar medium, then the onset of the afterglow will be delayed. Should the deceleration occur entirely within the swept-up thin shell, a rapid fade in the light curve will ensue. We identify two types of pulsar that can achieve the conditions necessary for altering the afterglow: low-field, long-lived pulsars, and high-field pulsars. We find that a sizable fraction (?20%-50%) of low-field pulsars are likely to reside in neutron star binaries based on observations, while their high-field counterparts are not. Hydrodynamical calculations motivated by this model are shown to be in good agreement with observations of sGRB afterglow light curves.

  2. Revisiting the dispersion measure of fast radio bursts associated with gamma-ray burst afterglows

    SciTech Connect (OSTI)

    Yu, Yun-Wei, E-mail: yuyw@mail.ccnu.edu.cn [Institute of Astrophysics, Central China Normal University, Wuhan 430079 (China)

    2014-12-01

    Some fast radio bursts (FRBs) are expected to be associated with the afterglow emission of gamma-ray bursts (GRBs), while a short-lived, supermassive neutron star (NS) forms during the GRBs. I investigate the possible contributions to the dispersion measure (DM) of the FRBs from the GRB ejecta and the wind blown from the precollapsing NS. On the one hand, sometimes an internal X-ray plateau afterglow could be produced by the NS wind, which indicates that a great number of electron-positron pairs are carried by the wind. If the pair-generation radius satisfies a somewhat rigorous condition, the relativistic and dense wind would contribute a high DM to the associated FRB, which can be comparable to and even exceed the DM contributed by the intergalactic medium. On the other hand, if the wind only carries a Goldreich-Julian particle flux, its DM contribution would become negligible; meanwhile, the internal plateau afterglow would not appear. Alternatively, the FRB should be associated with a GRB afterglow produced by the GRB external shock, i.e., an energy-injection-caused shallow-decay afterglow or a normal single-power-law afterglow if the impulsive energy release of the GRB is high enough. In the latter case, the DM contributed by the high-mass GRB ejecta could be substantially important, in particular, for an environment of main-sequence stellar wind. In summary, a careful assessment on the various DM contributors could be required for the cosmological application of the expected FRB-GRB association. The future DM measurements of GRB-associated FRBs could provide a constraint on the physics of NS winds.

  3. Hot electromagnetic outflows. III. Displaced fireball in a strong magnetic field

    SciTech Connect (OSTI)

    Thompson, Christopher; Gill, Ramandeep [Canadian Institute for Theoretical Astrophysics, 60 St. George Street, Toronto, ON M5S 3H8 (Canada)

    2014-08-10

    The evolution of a dilute electron-positron fireball is calculated in the regime of strong magnetization and high compactness (? ? 10{sup 3}-10{sup 8}). Heating is applied at a low effective temperature (<25 keV), appropriate to breakout from a confining medium, so that relaxation to a blackbody is inhibited by pair annihilation. The diffusion equation for Compton scattering by thermal pairs is coupled to a trans-relativistic cyclo-synchrotron source. We find that the photon spectrum develops a quasi-thermal peak at energy ?0.1 m{sub e}c {sup 2} in the comoving frame, with a power-law slope below it that is characteristic of gamma-ray bursts (GRBs; F{sub ?} ? const). The formation of a thermal high-energy spectrum is checked using the full kinetic equations. Calculations for a baryon-dominated photosphere reveal a lower spectral peak energy, and a harder low-energy spectrum, unless ion rest mass carries ? 10{sup 5} of the energy flux. We infer that (1) the GRB spectrum is inconsistent with the neutron-rich wind emitted by a young magnetar or neutron torus, and points to an event horizon in the engine; (2) neutrons play a negligible role in prompt gamma-ray emission; (3) the relation between observed peak frequency and burst energy is bounded below by the observed Amati relation if the Lorentz factor ?(opening angle){sup 1} at breakout, and the jet is surrounded by a broader sheath that interacts with a collapsing stellar core; (4) X-ray flashes are consistent with magnetized jets with ion-dominated photospheres; (5) high-frequency Alfvn waves may become charge starved in the dilute pair gas; (6) limitations on magnetic reconnection from plasma collisionality have been overestimated.

  4. High-resolution dynamically downscaled projections of precipitation in the mid and late 21st century over North America

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    none,

    2015-07-29

    This study performs high-spatial-resolution (12 km) Weather Research and Forecasting (WRF) simulations over a very large domain (7200 km × 6180 km, covering much of North America) to explore changes in mean and extreme precipitation in the mid and late 21st century under Representative Concentration Pathways 4.5 (RCP 4.5) and 8.5 (RCP 8.5). We evaluate WRF model performance for a historical simulation and future projections, applying the Community Climate System Model version 4 (CCSM4) as initial and boundary conditions with and without a bias correction. WRF simulations using boundary and initial conditions from both versions of CCSM4 show smaller biasesmore » versus evaluation data sets than does CCSM4 over western North America. WRF simulations also improve spatial details of precipitation over much of North America. However, driving the WRF with the bias-corrected CCSM4 does not always reduce the bias. WRF-projected changes in precipitation include decreasing intensity over the southwestern United States, increasing intensity over the eastern United States and most of Canada, and an increase in the number of days with heavy precipitation over much of North America. Projected precipitation changes are more evident in the late 21st century than the mid 21st century, and they are more evident under RCP 8.5 than under RCP 4.5 in the late 21st century. Uncertainties in the projected changes in precipitation due to different warming scenarios are non-negligible. Differences in summer precipitation changes between WRF and CCSM4 are significant over most of the United States.« less

  5. Measuring the seeds of ion outflow: auroral sounding rocket observations of low-altitude ion heating and circulation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Fernandes, P. A.; Lynch, K. A.; Zettergren, M.; Hampton, D. L.; Bekkeng, T. A.; Cohen, I. J.; Conde, M.; Fisher, L. E.; Horak, P.; Lessard, M. R.; et al

    2016-01-25

    Here, we present an analysis of in situ measurements from the MICA (Magnetosphere-Ionosphere Coupling in the Alfvén Resonator) nightside auroral sounding rocket with comparisons to a multifluid ionospheric model. MICA made observations at altitudes below 325 km of the thermal ion kinetic particle distributions that are the origins of ion outflow. Late flight, in the vicinity of an auroral arc, we observe frictional processes controlling the ion temperature. Upflow of these cold ions is attributed to either the ambipolar field resulting from the heated electrons or possibly to ion-neutral collisions. We measure E→xB→ convection away from the arc (poleward) andmore » downflows of hundreds of m s-1 poleward of this arc, indicating small-scale low-altitude plasma circulation. In the early flight we observe DC electromagnetic Poynting flux and associated ELF wave activity influencing the thermal ion temperature in regions of Alfvénic aurora. We observe enhanced, anisotropic ion temperatures which we conjecture are caused by transverse heating by wave-particle interactions (WPI) even at these low altitudes. Throughout this region we observe several hundred m s-1 upflow of the bulk thermal ions colocated with WPI; however, the mirror force is negligible at these low energies; thus, the upflow is attributed to ambipolar fields (or possibly neutral upwelling drivers). Moreover, the low-altitude MICA observations serve to inform future ionospheric modeling and simulations of (a) the need to consider the effects of heating by WPI at altitudes lower than previously considered viable and (b) the occurrence of structured and localized upflows/downflows below where higher-altitude heating rocesses are expected.« less

  6. Assessing the Thermal Environmental Impacts of an Groundwater Heat Pump in Southeastern Washington State

    SciTech Connect (OSTI)

    Freedman, Vicky L.; Waichler, Scott R.; Mackley, Rob D.; Horner, Jacob A.

    2012-04-01

    A thermal analysis of a large-scale (e.g., 1900 gpm), open-loop ground source heat pump (GSHP) installed on the Pacific Northwest National Laboratory (PNNL) campus in southeastern Washington State has been performed using a numerical modeling approach. Water temperature increases at the upgradient extraction wells in the system and at the downgradient Columbia River are potential concerns, especially since heat rejection to the subsurface will occur year-round. Hence, thermal impacts of the open-loop GSHP were investigated to identify operational scenarios that minimized downgradient environmental impacts at the river, and upgradient temperature drift at the production wells. Simulations examined the sensitivity of the system to variations in pumping rates and injected water temperatures, as well as to hydraulic conductivity estimates of the aquifer. Results demonstrated that both downgradient and upgradient thermal impacts were more sensitive to injection flow rates than estimates of hydraulic conductivity. Higher injection rates at lower temperatures resulted in higher temperature increases at the extraction wells but lower increases at the river. Conversely, lower pumping rates and higher injected water temperatures resulted in a smaller temperature increase at the extraction wells, but higher increases at the river. The scenario with lower pumping rates is operationally more efficient, but does increase the likelihood of a thermal plume discharging into the Columbia River. However, this impact would be mitigated by mixing within the hyporheic zone and the Columbia River. The impact under current operational conditions is negligible, but future increases in heat rejection could require a compromise between maximizing operational efficiency and minimizing temperature increases at the shoreline.

  7. Evaluation of Analytical and Numerical Techniques for Defining the Radius of Influence for an Open-Loop Ground Source Heat Pump System

    SciTech Connect (OSTI)

    Freedman, Vicky L.; Mackley, Rob D.; Waichler, Scott R.; Horner, Jacob A.

    2013-09-26

    In an open-loop groundwater heat pump (GHP) system, groundwater is extracted, run through a heat exchanger, and injected back into the ground, resulting in no mass balance changes to the flow system. Although the groundwater use is non-consumptive, the withdrawal and injection of groundwater may cause negative hydraulic and thermal impacts to the flow system. Because GHP is a relatively new technology and regulatory guidelines for determining environmental impacts for GHPs may not exist, consumptive use metrics may need to be used for permit applications. For consumptive use permits, a radius of influence is often used, which is defined as the radius beyond which hydraulic impacts to the system are considered negligible. In this paper, the hydraulic radius of influence concept was examined using analytical and numerical methods for a non-consumptive GHP system in southeastern Washington State. At this location, the primary hydraulic concerns were impacts to nearby contaminant plumes and a water supply well field. The results of this study showed that the analytical techniques with idealized radial flow were generally unsuited because they over predicted the influence of the well system. The numerical techniques yielded more reasonable results because they could account for aquifer heterogeneities and flow boundaries. In particular, the use of a capture zone analysis was identified as the best method for determining potential changes in current contaminant plume trajectories. The capture zone analysis is a more quantitative and reliable tool for determining the radius of influence with a greater accuracy and better insight for a non-consumptive GHP assessment.

  8. Numerical simulations used for a validity check on the laser induced photo-detachment diagnostic method in electronegative plasmas

    SciTech Connect (OSTI)

    Oudini, N.; Taccogna, F.; Aanesland, A.

    2014-06-15

    Laser photo-detachment is used as a method to measure or determine the negative ion density and temperature in electronegative plasmas. In essence, the method consists of producing an electropositive channel (negative ion free region) via pulsed laser photo-detachment within an electronegative plasma bulk. Electrostatic probes placed in this channel measure the change in the electron density. A second pulse might be used to track the negative ion recovery. From this, the negative ion density and temperature can be determined. We study the formation and relaxation of the electropositive channel via a two-dimensional Particle-In-Cell/Mote Carlo collision model. The simulation is mainly carried out in a Hydrogen plasma with an electronegativity of ??=?1, with a parametric study for ? up to 20. The temporal and spatial evolution of the plasma potential and the electron densities shows the formation of a double layer (DL) confining the photo-detached electrons within the electropositive channel. This DL evolves into two fronts that move in the opposite directions inside and outside of the laser spot region. As a consequence, within the laser spot region, the background and photo-detached electron energy distribution function relaxes/thermalizes via collisionless effects such as Fermi acceleration and Landau damping. Moreover, the simulations show that collisional effects and the DL electric field strength might play a non-negligible role in the negative ion recovery within the laser spot region, leading to a two-temperature negative ion distribution. The latter result might have important effects in the determination of the negative ion density and temperature from laser photo detachment diagnostic.

  9. Energy Assurance: Essential Energy Technologies for Climate Protection and Energy Security

    SciTech Connect (OSTI)

    Greene, David L; Boudreaux, Philip R; Dean, David Jarvis; Fulkerson, William; Gaddis, Abigail; Graham, Robin Lambert; Graves, Ronald L; Hopson, Dr Janet L; Hughes, Patrick; Lapsa, Melissa Voss; Mason, Thom; Standaert, Robert F; Wilbanks, Thomas J; Zucker, Alexander

    2009-12-01

    We present and apply a new method for analyzing the significance of advanced technology for achieving two important national energy goals: climate protection and energy security. Quantitative metrics for U.S. greenhouse gas emissions in 2050 and oil independence in 2030 are specified, and the impacts of 11 sets of energy technologies are analyzed using a model that employs the Kaya identity and incorporates the uncertainty of technological breakthroughs. The goals examined are a 50% to 80% reduction in CO2 emissions from energy use by 2050 and increased domestic hydrocarbon fuels supply and decreased demand that sum to 11 mmbd by 2030. The latter is intended to insure that the economic costs of oil dependence are not more than 1% of U.S. GDP with 95% probability by 2030. Perhaps the most important implication of the analysis is that meeting both energy goals requires a high probability of success (much greater than even odds) for all 11 technologies. Two technologies appear to be indispensable for accomplishment of both goals: carbon capture and storage, and advanced fossil liquid fuels. For reducing CO2 by more than 50% by 2050, biomass energy and electric drive (fuel cell or battery powered) vehicles also appear to be necessary. Every one of the 11 technologies has a powerful influence on the probability of achieving national energy goals. From the perspective of technology policy, conflict between the CO2 mitigation and energy security is negligible. These general results appear to be robust to a wide range of technology impact estimates; they are substantially unchanged by a Monte Carlo simulation that allows the impacts of technologies to vary by 20%.

  10. Comprehensive mechanisms for combustion chemistry: Experiment, modeling, and sensitivity analysis

    SciTech Connect (OSTI)

    Dryer, F.L.; Yetter, R.A.

    1993-12-01

    This research program is an integrated experimental/numerical effort to study pyrolysis and oxidation reactions and mechanisms for small-molecule hydrocarbon structures under conditions representative of combustion environments. The experimental aspects of the work are conducted in large diameter flow reactors, at pressures from one to twenty atmospheres, temperatures from 550 K to 1200 K, and with observed reaction times from 10{sup {minus}2} to 5 seconds. Gas sampling of stable reactant, intermediate, and product species concentrations provides not only substantial definition of the phenomenology of reaction mechanisms, but a significantly constrained set of kinetic information with negligible diffusive coupling. Analytical techniques used for detecting hydrocarbons and carbon oxides include gas chromatography (GC), and gas infrared (NDIR) and FTIR methods are utilized for continuous on-line sample detection of light absorption measurements of OH have also been performed in an atmospheric pressure flow reactor (APFR), and a variable pressure flow (VPFR) reactor is presently being instrumented to perform optical measurements of radicals and highly reactive molecular intermediates. The numerical aspects of the work utilize zero and one-dimensional pre-mixed, detailed kinetic studies, including path, elemental gradient sensitivity, and feature sensitivity analyses. The program emphasizes the use of hierarchical mechanistic construction to understand and develop detailed kinetic mechanisms. Numerical studies are utilized for guiding experimental parameter selections, for interpreting observations, for extending the predictive range of mechanism constructs, and to study the effects of diffusive transport coupling on reaction behavior in flames. Modeling using well defined and validated mechanisms for the CO/H{sub 2}/oxidant systems.

  11. SU-E-J-129: A Strategy to Consolidate the Image Database of a VERO Unit Into a Radiotherapy Management System

    SciTech Connect (OSTI)

    Yan, Y; Medin, P; Yordy, J; Zhao, B; Jiang, S

    2014-06-01

    Purpose: To present a strategy to integrate the imaging database of a VERO unit with a treatment management system (TMS) to improve clinical workflow and consolidate image data to facilitate clinical quality control and documentation. Methods: A VERO unit is equipped with both kV and MV imaging capabilities for IGRT treatments. It has its own imaging database behind a firewall. It has been a challenge to transfer images on this unit to a TMS in a radiation therapy clinic so that registered images can be reviewed remotely with an approval or rejection record. In this study, a software system, iPump-VERO, was developed to connect VERO and a TMS in our clinic. The patient database folder on the VERO unit was mapped to a read-only folder on a file server outside VERO firewall. The application runs on a regular computer with the read access to the patient database folder. It finds the latest registered images and fuses them in one of six predefined patterns before sends them via DICOM connection to the TMS. The residual image registration errors will be overlaid on the fused image to facilitate image review. Results: The fused images of either registered kV planar images or CBCT images are fully DICOM compatible. A sentinel module is built to sense new registered images with negligible computing resources from the VERO ExacTrac imaging computer. It takes a few seconds to fuse registered images and send them to the TMS. The whole process is automated without any human intervention. Conclusion: Transferring images in DICOM connection is the easiest way to consolidate images of various sources in your TMS. Technically the attending does not have to go to the VERO treatment console to review image registration prior delivery. It is a useful tool for a busy clinic with a VERO unit.

  12. Field simulation of axisymmetric plasma screw pinches by alternating-direction-implicit methods

    SciTech Connect (OSTI)

    Lambert, M.A.

    1996-06-01

    An axisymmetric plasma screw pinch is an axisymmetric column of ionized gaseous plasma radially confined by forces from axial and azimuthal currents driven in the plasma and its surroundings. This dissertation is a contribution to detailed, high resolution computer simulation of dynamic plasma screw pinches in 2-d {ital rz}-coordinates. The simulation algorithm combines electron fluid and particle-in-cell (PIC) ion models to represent the plasma in a hybrid fashion. The plasma is assumed to be quasineutral; along with the Darwin approximation to the Maxwell equations, this implies application of Ampere`s law without displacement current. Electron inertia is assumed negligible so that advective terms in the electron momentum equation are ignored. Electrons and ions have separate scalar temperatures, and a scalar plasma electrical resistivity is assumed. Altemating-direction-implicit (ADI) methods are used to advance the electron fluid drift velocity and the magnetic fields in the simulation. The ADI methods allow time steps larger than allowed by explicit methods. Spatial regions where vacuum field equations have validity are determined by a cutoff density that invokes the quasineutral vacuum Maxwell equations (Darwin approximation). In this dissertation, the algorithm was first checked against ideal MM stability theory, and agreement was nicely demonstrated. However, such agreement is not a new contribution to the research field. Contributions to the research field include new treatments of the fields in vacuum regions of the pinch simulation. The new treatments predict a level of magnetohydrodynamic turbulence near the bulk plasma surface that is higher than predicted by other methods.

  13. Interdiffusion and Reaction between Zr and Al Alloys from 425 degrees to 625 degrees C

    SciTech Connect (OSTI)

    J. Dickson; L. Zhou; A. Ewh; M. Fu; D. D. Keiser, Jr.; Y. H. Sohn; A. Paz y Puente

    2014-06-01

    Zirconium has recently garnered attention for use as a diffusion barrier between UMo nuclear fuels and Al cladding alloys. Interdiffusion and reactions between Zr and Al, Al-2 wt.% Si, Al-5 wt.% Si or AA6061 were investigated using solid-to-solid diffusion couples annealed in the temperature range of 425 degrees to 625 degrees C. In the binary Al and Zr system, the Al3Zr and Al2Zr phases were identified, and the activation energy for the growth of the Al3Zr phase was determined to be 347 kJ/mol. Negligible diffusional interactions were observed for diffusion couples between Zr vs. Al-2 wt.% Si, Al-5 wt.% Si and AA6061 annealed at or below 475 degrees C. In diffusion couples with the binary AlSi alloys at 560 degrees C, a significant variation in the development of the phase constituents was observed including the thick t1 (Al5SiZr2) with Si content up to 12 at.%, and thin layers of (Si,Al)2Zr, (Al,Si)3Zr, Al3SiZr2 and Al2Zr phases. The use of AA6061 as a terminal alloy resulted in the development of both T1 (Al5SiZr2) and (Al,Si)3Zr phases with a very thin layer of (Al,Si)2Zr. At 560 degrees C, with increasing Si content in the AlSi alloy, an increase in the overall rate of diffusional interaction was observed; however, the diffusional interaction of Zr in contact with multicomponent AA6061 with 0.40.8 wt.% Si was most rapid.

  14. NEW MEASUREMENTS OF THE COSMIC INFRARED BACKGROUND FLUCTUATIONS IN DEEP SPITZER/IRAC SURVEY DATA AND THEIR COSMOLOGICAL IMPLICATIONS

    SciTech Connect (OSTI)

    Kashlinsky, A.; Arendt, R. G.; Mather, J.; Moseley, S. H.; Ashby, M. L. N.; Fazio, G. G.

    2012-07-01

    We extend previous measurements of cosmic infrared background (CIB) fluctuations to {approx}< 1 Degree-Sign using new data from the Spitzer Extended Deep Survey. Two fields with depths of {approx_equal} 12 hr pixel{sup -1} over three epochs are analyzed at 3.6 and 4.5 {mu}m. Maps of the fields were assembled using a self-calibration method uniquely suitable for probing faint diffuse backgrounds. Resolved sources were removed from the maps to a magnitude limit of mag{sub AB} {approx_equal} 25, as indicated by the level of the remaining shot noise. The maps were then Fourier transformed and their power spectra were evaluated. Instrumental noise was estimated from the time-differenced data, and subtracting this isolates the spatial fluctuations of the actual sky. The power spectra of the source-subtracted fields remain identical (within the observational uncertainties) for the three epochs indicating that zodiacal light contributes negligibly to the fluctuations. Comparing to 8 {mu}m power spectra shows that Galactic cirrus cannot account for the fluctuations. The signal appears isotropically distributed on the sky as required for an extragalactic origin. The CIB fluctuations continue to diverge to >10 times those of known galaxy populations on angular scales out to {approx}< 1 Degree-Sign . The low shot-noise levels remaining in the diffuse maps indicate that the large-scale fluctuations arise from the spatial clustering of faint sources well below the confusion noise. The spatial spectrum of these fluctuations is in reasonable agreement with an origin in populations clustered according to the standard cosmological model ({Lambda}CDM) at epochs coinciding with the first stars era.

  15. ELEMENTAL ABUNDANCE RATIOS IN STARS OF THE OUTER GALACTIC DISK. IV. A NEW SAMPLE OF OPEN CLUSTERS

    SciTech Connect (OSTI)

    Yong, David; Carney, Bruce W.; Friel, Eileen D. E-mail: bruce@physics.unc.edu

    2012-10-01

    We present radial velocities and chemical abundances for nine stars in the old, distant open clusters Be18, Be21, Be22, Be32, and PWM4. For Be18 and PWM4, these are the first chemical abundance measurements. Combining our data with literature results produces a compilation of some 68 chemical abundance measurements in 49 unique clusters. For this combined sample, we study the chemical abundances of open clusters as a function of distance, age, and metallicity. We confirm that the metallicity gradient in the outer disk is flatter than the gradient in the vicinity of the solar neighborhood. We also confirm that the open clusters in the outer disk are metal-poor with enhancements in the ratios [{alpha}/Fe] and perhaps [Eu/Fe]. All elements show negligible or small trends between [X/Fe] and distance (<0.02 dex kpc{sup -1}), but for some elements, there is a hint that the local (R{sub GC} < 13 kpc) and distant (R{sub GC} > 13 kpc) samples may have different trends with distance. There is no evidence for significant abundance trends versus age (<0.04 dex Gyr{sup -1}). We measure the linear relation between [X/Fe] and metallicity, [Fe/H], and find that the scatter about the mean trend is comparable to the measurement uncertainties. Comparison with solar neighborhood field giants shows that the open clusters share similar abundance ratios [X/Fe] at a given metallicity. While the flattening of the metallicity gradient and enhanced [{alpha}/Fe] ratios in the outer disk suggest a chemical enrichment history different from that of the solar neighborhood, we echo the sentiments expressed by Friel et al. that definitive conclusions await homogeneous analyses of larger samples of stars in larger numbers of clusters. Arguably, our understanding of the evolution of the outer disk from open clusters is currently limited by systematic abundance differences between various studies.

  16. THE INFLUENCE OF DARK MATTER HALOS ON DYNAMICAL ESTIMATES OF BLACK HOLE MASS: 10 NEW MEASUREMENTS FOR HIGH-{sigma} EARLY-TYPE GALAXIES

    SciTech Connect (OSTI)

    Rusli, S. P.; Thomas, J.; Saglia, R. P.; Fabricius, M.; Erwin, P.; Bender, R.; Nowak, N.; Lee, C. H.; Riffeser, A.; Sharp, R.

    2013-09-15

    Adaptive optics assisted SINFONI observations of the central regions of 10 early-type galaxies are presented. Based primarily on the SINFONI kinematics, 10 black hole (BH) masses occupying the high-mass regime of the M{sub BH}-{sigma} relation are derived using three-integral Schwarzschild models. The effect of dark matter (DM) inclusion on the BH mass is explored. The omission of a DM halo in the model results in a higher stellar mass-to-light ratio, especially when extensive kinematic data are used in the model. However, when the diameter of the sphere of influence-computed using the BH mass derived without a dark halo-is at least 10 times the point-spread function FWHM during the observations, it is safe to exclude a DM component in the dynamical modeling, i.e., the change in BH mass is negligible. When the spatial resolution is marginal, restricting the mass-to-light ratio to the right value returns the correct M{sub BH} although a dark halo is not present in the model. Compared to the M{sub BH}-{sigma} and M{sub BH}-L relations of McConnell et al., the 10 BHs are all more massive than expected from the luminosities and 7 BH masses are higher than expected from the stellar velocity dispersions of the host bulges. Using new fitted relations, which include the 10 galaxies, we find that the space density of the most massive BHs (M{sub BH} {approx}> 10{sup 9} M{sub Sun }) estimated from the M{sub BH}-L relation is higher than the estimate based on the M{sub BH}-{sigma} relation and the latter is higher than model predictions based on quasar counts, each by about an order of magnitude.

  17. SciFri PM: Topics 08: The Role and Benefits of Electromagnetic Needle-Tracking Technologies in Brachytherapy

    SciTech Connect (OSTI)

    Beaulieu, L.; Racine, E.; Boutaleb, S.; Filion, O.; Poulin, E.; Hautvast, G.; Binnekamp, D.

    2014-08-15

    In modern brachytherapy, application of large doses of ionizing radiation in a limited number of fractions is frequent. Furthermore, as with any surgical procedures, brachytherapy is subject to learning curve effects. In this context, there could be advantages of integrating real-time tracking of needles/catheters to existing protocols given the recent prominent advances in tracking technologies. In this work, we review the use of an electromagnetic tracking system (EMTS) based on the second generation Aurora Planar Field Generator (Northern Digital Inc) and custom design needles (Philips Healthcare) for brachytherapy applications. The position and orientation information is obtained from 5 degrees of freedom sensors. Basic system performance characterization is performed in well-controlled conditions to establish accuracy and reproducibility as well as potential interference from standard brachytherapy equipment. The results show that sensor locations can be tracked to within 0.04mm (la) when located within 26cm of the generator. Orientation accuracy of the needle remained within 1 in the same region, but rose quickly at larger distances. The errors on position and orientation strongly dependent the sensor position in the characterization volume (500500500mm{sup 3}). The presence of an ultrasound probe was shown to have negligible effects on tracking accuracy. The use of EMTS for automatic catheter/applicator reconstruction was also explored. Reconstruction time was less than 10 sec/channel and tips identification was within 0.690.29mm of the reference values. Finally, we demonstrate that hollow needle designs with special EM adaptation also allow for real-time seed drop position estimation. In phantom experiments showed that drop positions were on average within 1.60.9mm of the reference position measured from ?CT. Altogether, EMTS offer promising benefits in a wide range of brachytherapy applications.

  18. First Demonstration of Combined kV/MV Image-Guided Real-Time Dynamic Multileaf-Collimator Target Tracking

    SciTech Connect (OSTI)

    Cho, Byungchul Poulsen, Per R.; Sloutsky, Alex; Sawant, Amit; Keall, Paul J.

    2009-07-01

    Purpose: For intrafraction motion management, a real-time tracking system was developed by combining fiducial marker-based tracking via simultaneous kilovoltage (kV) and megavoltage (MV) imaging and a dynamic multileaf collimator (DMLC) beam-tracking system. Methods and Materials: The integrated tracking system employed a Varian Trilogy system equipped with kV/MV imaging systems and a Millennium 120-leaf MLC. A gold marker in elliptical motion (2-cm superior-inferior, 1-cm left-right, 10 cycles/min) was simultaneously imaged by the kV and MV imagers at 6.7 Hz and segmented in real time. With these two-dimensional projections, the tracking software triangulated the three-dimensional marker position and repositioned the MLC leaves to follow the motion. Phantom studies were performed to evaluate time delay from image acquisition to MLC adjustment, tracking error, and dosimetric impact of target motion with and without tracking. Results: The time delay of the integrated tracking system was {approx}450 ms. The tracking error using a prediction algorithm was 0.9 {+-} 0.5 mm for the elliptical motion. The dose distribution with tracking showed better target coverage and less dose to surrounding region over no tracking. The failure rate of the gamma test (3%/3-mm criteria) was 22.5% without tracking but was reduced to 0.2% with tracking. Conclusion: For the first time, a complete tracking system combining kV/MV image-guided target tracking and DMLC beam tracking was demonstrated. The average geometric error was less than 1 mm, and the dosimetric error was negligible. This system is a promising method for intrafraction motion management.

  19. A FLUX ROPE ERUPTION TRIGGERED BY JETS

    SciTech Connect (OSTI)

    Guo Juan; Zhang Hongqi; Deng Yuanyong; Lin Jiaben; Su Jiangtao; Liu Yu

    2010-03-10

    We present an observation of a filament eruption caused by recurrent chromospheric plasma injections (surges/jets) on 2006 July 6. The filament eruption was associated with an M2.5 two-ribbon flare and a coronal mass ejection (CME). There was a light bridge in the umbra of the main sunspot of NOAA 10898; one end of the filament was terminated at the region close to the light bridge, and recurrent surges were observed to be ejected from the light bridge. The surges occurred intermittently for about 8 hr before the filament eruption, and finally a clear jet was found at the light bridge to trigger the filament eruption. We analyzed the evolutions of the relative darkness of the filament and the loaded mass by the continuous surges quantitatively. It was found that as the occurrence of the surges, the relative darkness of the filament body continued growing for about 3-4 hr, reached its maximum, and kept stable for more than 2 hr until it erupted. If suppose 50% of the ejected mass by the surges could be trapped by the filament channel, then the total loaded mass into the filament channelwill be about 0.57x10{sup 16} g with a momentum of 0.57x10{sup 22} g cm s{sup -1} by 08:08 UT, which is a non-negligible effect on the stability of the filament. Based on the observations, we present a model showing the important role that recurrent chromospheric mass injection play in the evolution and eruption of a flux rope. Our study confirms that the surge activities can efficiently supply the necessary material for some filament formation. Furthermore, our study indicates that the continuous mass with momentum loaded by the surge activities to the filament channel could make the filament unstable and cause it to erupt.

  20. Systematic characterization of degas-driven flow for poly(dimethylsiloxane) microfluidic devices

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liang, David Y.; Tentori, Augusto M.; Dimov, Ivan K.; Lee, Luke P.

    2011-01-01

    Degas-driven flow is a novel phenomenon used to propel fluids in poly(dimethylsiloxane) (PDMS)-based microfluidic devices without requiring any external power. This method takes advantage of the inherently high porosity and air solubility of PDMS by removing air molecules from the bulk PDMS before initiating the flow. The dynamics of degas-driven flow are dependent on the channel and device geometries and are highly sensitive to temporal parameters. These dependencies have not been fully characterized, hindering broad use of degas-driven flow as a microfluidic pumping mechanism. Here, we characterize, for the first time, the effect of various parameters on the dynamics ofmore » degas-driven flow, including channel geometry, PDMS thickness, PDMS exposure area, vacuum degassing time, and idle time at atmospheric pressure before loading. We investigate the effect of these parameters on flow velocity as well as channel fill time for the degas-driven flow process. Using our devices, we achieved reproducible flow with a standard deviation of less than 8% for flow velocity, as well as maximum flow rates of up to 3 nL/s and mean flow rates of approximately 1-1.5 nL/s. Parameters such as channel surface area and PDMS chip exposure area were found to have negligible impact on degas-driven flow dynamics, whereas channel cross-sectional area, degas time, PDMS thickness, and idle time were found to have a larger impact. In addition, we develop a physical model that can predict mean flow velocities within 6% of experimental values and can be used as a tool for future design of PDMS-based microfluidic devices that utilize degas-driven flow.« less

  1. Electron Flood Charge Compensation Device for Ion Trap Secondary Ion Mass Spectrometry

    SciTech Connect (OSTI)

    Appelhans, Anthony David; Ward, Michael Blair; Olson, John Eric

    2002-11-01

    During secondary ion mass spectrometry (SIMS) analyses of organophosphorous compounds adsorbed onto soils, the measured anion signals were lower than expected and it was hypothesized that the low signals could be due to sample charging. An electron flood gun was designed, constructed and used to investigate sample charging of these and other sample types. The flood gun was integrated into one end cap of an ion trap secondary ion mass spectrometer and the design maintained the geometry of the self-stabilizing extraction optics used in this instrument. The SIMION ion optics program was used to design the flood gun, and experimental results agreed with the predicted performance. Results showed the low anion signals from the soils were not due to sample charging. Other insulating and conducting samples were tested using both a ReO4- and a Cs+ primary ion beam. The proximity of the sample and electron source to the ion trap aperture resulted in generation of background ions in the ion trap via electron impact (EI) ionization during the period the electron gun was flooding the sample region. When using the electron gun with the ReO4- primary beam, the required electron current was low enough that the EI background was negligible; however, the high electron flood current required with the Cs+ beam produced background EI ions that degraded the quality of the mass spectra. The consequences of the EI produced cations will have to be evaluated on a sample-by-sample basis when using electron flood. It was shown that the electron flood gun could be intentionally operated to produce EI spectra in this instrument. This offers the opportunity to measure, nearly simultaneously, species evaporating from a sample, via EI, and species bound to the surface, via SIMS.

  2. Red giant stars from Sloan Digital Sky Survey. I. The general field

    SciTech Connect (OSTI)

    Chen, Y. Q.; Zhao, G.; Carrell, K.; Zhao, J. K.; Tan, K. F.; Nissen, P. E.; Wei, P. E-mail: pen@phys.au.dk

    2014-11-01

    We have obtained a sample of ?22,000 red giant branch (RGB) stars based on stellar parameters, provided by the ninth data release of the Sloan Digital Sky Survey, and the CH(G)/MgH indices, measured from the included spectra. The Galactic rest-frame velocity of V {sub gsr} versus longitude for the sample shows the existence of several groups of stars from globular clusters and known streams. Excluding these substructures, a sample of ?16,000 RGB stars from the general field is used to investigate the properties of the thick disk, the inner halo, and the outer halo of our Galaxy. The metallicity and rotational velocity distributions are investigated for stars at 0 kpc < |Z| < 10 kpc. It is found that the canonical thick disk dominates at 0 kpc < |Z| < 2 kpc and its contribution becomes negligible at |Z| > 3 kpc. The MWTD is present and overlaps with the inner halo at 1 kpc < |Z| < 3 kpc. The inner halo starts at 2 kpc < |Z| < 3 kpc and becomes the dominated population for 4 kpc < |Z| < 10 kpc. For halo stars with |Z| > 5 kpc, bimodal metallicity distributions are found for 20 kpc < |Z| < 25 kpc and 35 kpc < RR < 45 kpc, which suggests a dual halo, the inner and the outer halo, as reported in Carollo et al. at low |Z| values. The peak of metallicity for the inner halo is at [Fe/H] ? 1.6 and appears to be at [Fe/H] ? 2.3 for the outer halo. The transition point from the inner to the outer halo is located at |Z| ? 20 kpc and RR ? 35 kpc.

  3. SU-E-J-193: Feasibility of MRI-Only Based IMRT Planning for Pancreatic Cancer

    SciTech Connect (OSTI)

    Prior, P; Botros, M; Chen, X; Paulson, E; Erickson, B; Li, X

    2014-06-01

    Purpose: With the increasing use of MRI simulation and the advent of MRI-guided delivery, it is desirable to use MRI only for treatment planning. In this study, we assess the dosimetric difference between MRI- and CTbased IMRT planning for pancreatic cancer. Methods: Planning CTs and MRIs acquired for a representative pancreatic cancer patient were used. MRI-based planning utilized forced relative electron density (rED) assignment of organ specific values from IRCU report 46, where rED = 1.029 for PTV and a rED = 1.036 for non-specified tissue (NST). Six IMRT plans were generated with clinical dose-volume (DV) constraints using a research Monaco planning system employing Monte Carlo dose calculation with optional perpendicular magnetic field (MF) of 1.5T. The following five plans were generated and compared with the planning CT: 1.) CT plan with MF and dose recalculation without optimization; 2.) MRI (T2) plan with target and OARs redrawn based on MRI, forced rED, no MF, and recalculation without optimization; 3.) Similar as in 2 but with MF; 4.) MRI plan with MF but without optimization; and 5.) Similar as in 4 but with optimization. Results: Generally, noticeable differences in PTV point doses and DV parameters (DVPs) between the CT-and MRI-based plans with and without the MF were observed. These differences between the optimized plans were generally small, mostly within 2%. Larger differences were observed in point doses and mean doses for certain OARs between the CT and MRI plan, mostly due to differences between image acquisition times. Conclusion: MRI only based IMRT planning for pancreatic cancer is feasible. The differences observed between the optimized CT and MRI plans with or without the MF were practically negligible if excluding the differences between MRI and CT defined structures.

  4. The effect of climate change, population distribution, and climate mitigation on building energy use in the U.S. and China

    SciTech Connect (OSTI)

    Zhou, Yuyu; Eom, Jiyong; Clarke, Leon E.

    2013-08-01

    A changing climate will affect the energy system in a number of ways, one of which is through changes in demands for heating and cooling in buildings. Understanding the potential effect of climate on heating and cooling demands must take into account not only the manner in which the building sector might evolve over time - including, for example, movements from rural to urban environments in developing countries - but also important uncertainty about the nature of climate change itself and the growth and movements of populations over time. In this study, we explored the uncertainty in climate change impacts on heating and cooling by constructing estimates of heating and cooling degree days for both a reference (no-policy) scenario and a climate mitigation scenario built from 0.5 degree latitude by 0.5 degree longitude resolution output from three different Global Climate Models (GCMs) and three gridded scenarios of population distribution. The implications that changing climate and population distribution might have for building energy consumption in the U.S. and China were then explored by using the heating and cooling degree days results as inputs to a detailed, building energy model, nested in the long-term global integrated assessment framework, Global Change Assessment Model (GCAM). Across the climate models and population distribution scenarios, the results indicate that unabated climate change would cause total final energy consumption to decrease modestly in both U.S. and China buildings by the end of the century, as decreased heating consumption is more than balanced by increased cooling using primarily electricity. However, the results also indicate that when indirect emissions from the power sector are also taken into account, climate change may have negligible effect on building sector CO2 emissions in the two countries. The variation in results due to variation of population distribution is noticeably smaller than variation due to the use of different climate models.

  5. A modeling study of irrigation effects on global surface water and groundwater resources under a changing climate

    SciTech Connect (OSTI)

    Leng, Guoyong; Huang, Maoyi; Tang, Qiuhong; Leung, Lai-Yung R.

    2015-08-25

    Abstract In this study, the effects of irrigation on global surface water (SW) and groundwater (GW) resources are investigated by performing simulations using Community Land Model 4.0 (CLM4) at 0.5-degree resolution driven by downscaled/bias-corrected historical simulations and future projections from five General Circulation Models (GCMs) for 1950-2099. For each climate scenario, three sets of numerical experiments were configured: (1) a control experiment (CTRL) in which all crops are assumed to be rainfed; (2) an irrigation experiment (IRRIG) in which the irrigation module using only SW for irrigation is activated; and (3) a groundwater pumping experiment (PUMP) in which a groundwater pumping scheme coupled with the irrigation module is activated for conjunctive use of SW and GW for irrigation. The parameters associated with irrigation and groundwater pumping are calibrated based on a global inventory of census-based SW and GW use compiled by the Food and Agricultural Organization (FAO). Our results suggest that irrigation could lead to two major opposing effects: SW depletion/GW accumulation in regions with irrigation primarily fed by SW, and SW accumulation/GW depletion in regions with irrigation fed primarily by GW. Furthermore, irrigation depending primarily on SW tends to have larger impacts on low-flow than high-flow conditions, suggesting the potential to increase vulnerability to drought. By the end of the 21st century (2070-2099), climate change significantly increases (relative to 1971-2000) irrigation water demand across the world. Combined with the increased temporal-spatial variability of water supply, this may lead to severe issues of local water scarcity for irrigation. Regionally, irrigation has the potential to aggravate/alleviate climate-induced changes of SW/GW although such effects are negligible when averaged globally. Our results emphasize the importance of accounting for irrigation effects and irrigation sources in regional climate change impact assessment.

  6. Ratios of W and Z cross sections at large boson $p_T$ as a constraint on PDFs and background to new physics

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Malik, Sarah Alam; Watt, Graeme

    2014-02-05

    We motivate a measurement of various ratios of W and Z cross sections at the Large Hadron Collider (LHC) at large values of the boson transverse momentum (p T ≳ M W,Z ). We study the dependence of predictions for these cross-section ratios on the multiplicity of associated jets, the boson p T and the LHC centre-of-mass energy. We present the flavour decomposition of the initial-state partons and an evaluation of the theoretical uncertainties. We also show that the W + /W - ratio is sensitive to the up-quark to down-quark ratio of parton distribution functions (PDFs), while other theoreticalmore » uncertainties are negligible, meaning that a precise measurement of the W + /W - ratio at large boson p T values could constrain the PDFs at larger momentum fractions x than the usual inclusive W charge asymmetry. The W ± /Z ratio is insensitive to PDFs and most other theoretical uncertainties, other than possibly electroweak corrections, and a precise measurement will therefore be useful in validating theoretical predictions needed in data-driven methods, such as using W (→ ℓν) + jets events to estimate the Z(→ νν¯) + jets background in searches for new physics at the LHC. Furthermore, the differential W and Z cross sections themselves, dσ/dp T , have the potential to constrain the gluon distribution, provided that theoretical uncertainties from higher-order QCD and electroweak corrections are brought under control, such as by inclusion of anticipated next-to-next-to-leading order QCD corrections.« less

  7. Apparent thermal conductivity measurements by an unguarded technique

    SciTech Connect (OSTI)

    Graves, R.S.; Yarbrough, D.W.; McElroy, D.L.

    1983-01-01

    An unguarded longitudinal heat-flow apparatus for measuring the apparent thermal conductivity (lambda/sub a) of insulations was tested with mean specimen temperatures from 300 to 330/sup 0/K on samples up to 0.91 m wide, 1.52 m long, and 0.15 m thick. Heat flow is provided by a horizontal electrically heated Nichrome screen sandwiched between test samples that are bounded by temperature controlled copper plates and 9 cm of mineral fiber insulation. A determinate error analysis shows lambda/sub a/ measurement uncertainty to be less than +- 1.7% for insulating materials as thin as 3 cm. Three-dimensional thermal modeling indicates negligible error in lambda/sub a/ due to edge loss for insulations up to 7.62 cm thick when the temperature difference across the sample is measured at the sceen center. System repeatability and reproducibility were determined to be +- 0.2%. Differences of lambda/sub a/ results from the screen tester and results from the National Bureau of Standards were 0.1% for a 10-kg/m/sup 3/ Calibration Transfer Standard and 0.9% for 127-kg/m/sup 3/ fibrous glass board (SRM 1450b). Measurements on fiberglass and rock wool batt insulations showed the dependence of lambda/sub a/ on density, temperature, temperature difference, plate emittance, and heat flow direction. Results obtained for lambda/sub a/ as a function of density at 24/sup 0/C differed by less than 2% from values obtained with a guarded hot plate. These results demonstrate that this simple technique has the accuracy and sensitivity needed for useful lambda/sub a/ measurements on thermal insulating materials.

  8. Laminar flamelet structure at low and vanishing scalar dissipation rate

    SciTech Connect (OSTI)

    Bai, X.S.; Fuchs, L.; Mauss, F.

    2000-02-01

    The laminar flamelet structures of methane/air, propane/air, and hydrogen/air nonpremixed combustion at low and vanishing scalar dissipation rates are investigated, by numerical calculations of a system of conservation equations in a counterflow diffusion flame configuration, together with a transport equation defining the mixture fraction and scalar dissipation rate. The chemical reaction mechanisms consist of 82 elementary reactions up to C{sub 3} species. In the limit of vanishing scalar dissipation rate, two types of structures are shown to appear. In one structure fuel and oxygen are consumed in a thin layer located near the stoichiometric mixture fraction, Z{sub st}, where the temperature and the major products reach their peaks. This is similar to the so-called Burke-Schumann single layer flame sheet structure. One example is the hydrogen/air diffusion flame. The second structure consists of multilayers. Fuel and oxygen are consumed at different locations. Oxygen is consumed at Z{sub l} (near Z{sub st}), where the temperature and the major products reach their peaks. Fuel is consumed at Z{sub r} (>Z{sub st}). Between Z{sub l} and Z{sub r} some intermediate and radical species are found in high concentrations. Hydrocarbon/air nonpremixed flames are of this type. It is shown that for methane/air diffusion flames, some chemical reactions which are negligible at large scalar dissipation rate near flame quenching conditions, play essential roles for the existence of the multilayer structure. This result is used to successfully explain the high CO emissions in a turbulent methane/air diffusion flame.

  9. Kinetic extensions of magnetohydrodynamic models for axisymmetric toroidal plasmas

    SciTech Connect (OSTI)

    Cheng, C.Z.

    1989-04-01

    A nonvariational kinetic-MHD stability code (NOVA-K) has been developed to integrate a set of non-Hermitian integro-differential eigenmode equations due to energetic particles for axisymmetric toroidal plasmas in a general flux coordinate system with an arbitrary Jacobian. The NOVA-K code employs the Galerkin method involving Fourier expansions in the generalized poloidal angle theta and generalized toroidal angle /zeta/ directions, and cubic-B spline finite elements in the radial /Psi/ direction. Extensive comparisons with the existing variational ideal MHD codes show that the ideal MHD version of the NOVA-K code converges faster and gives more accurate results. The NOVA-K code is employed to study the effects of energetic particles on MHD-type modes: the stabilization of ideal MHD internal kink modes and the excitation of ''fishbone'' internal kink modes; and the alpha particle destabilization of toroidicity-induced Alfven eigenmodes (TAE) via transit resonances. Analytical theories are also presented to help explain the NOVA-K results. For energetic trapped particles generated by neutral beam injection (NBI) or ion cyclotron resonant heating (ICRH), a stability window for the n = 1 internal kink mode in the hot particle beta space exists even in the absence of the core ion finite Larmor radius effect. On the other hand, the trapped alpha particles are found to have negligible effects on the stability of the n = 1 internal kink mode, but the circulating alpha particles can strongly destabilize TAE modes via inverse Landau damping associated with the spatial gradient of the alpha particle pressure. 60 refs., 24 figs., 1 tab.

  10. Determination of Transport Properties From Flowing Fluid Temperature LoggingIn Unsaturated Fractured Rocks: Theory And Semi-Analytical Solution

    SciTech Connect (OSTI)

    Mukhopadhyay, Sumit; Tsang, Yvonne W.

    2008-08-01

    Flowing fluid temperature logging (FFTL) has been recently proposed as a method to locate flowing fractures. We argue that FFTL, backed up by data from high-precision distributed temperature sensors, can be a useful tool in locating flowing fractures and in estimating the transport properties of unsaturated fractured rocks. We have developed the theoretical background needed to analyze data from FFTL. In this paper, we present a simplified conceptualization of FFTL in unsaturated fractured rock, and develop a semianalytical solution for spatial and temporal variations of pressure and temperature inside a borehole in response to an applied perturbation (pumping of air from the borehole). We compare the semi-analytical solution with predictions from the TOUGH2 numerical simulator. Based on the semi-analytical solution, we propose a method to estimate the permeability of the fracture continuum surrounding the borehole. Using this proposed method, we estimated the effective fracture continuum permeability of the unsaturated rock hosting the Drift Scale Test (DST) at Yucca Mountain, Nevada. Our estimate compares well with previous independent estimates for fracture permeability of the DST host rock. The conceptual model of FFTL presented in this paper is based on the assumptions of single-phase flow, convection-only heat transfer, and negligible change in system state of the rock formation. In a sequel paper [Mukhopadhyay et al., 2008], we extend the conceptual model to evaluate some of these assumptions. We also perform inverse modeling of FFTL data to estimate, in addition to permeability, other transport parameters (such as porosity and thermal conductivity) of unsaturated fractured rocks.

  11. Static jaw collimation settings to minimize radiation dose to normal brain tissue during stereotactic radiosurgery

    SciTech Connect (OSTI)

    Han, Eun Young; Zhang Xin; Yan Yulong; Sharma, Sunil; Penagaricano, Jose; Moros, Eduardo; Corry, Peter

    2012-01-01

    At University of Arkansas for Medical Sciences (UAMS) intracranial stereotactic radiosurgery (SRS) is performed by using a linear accelerator with an add-on micromultileaf collimator (mMLC). In our clinical setting, static jaws are automatically adapted to the furthest edge of the mMLC-defined segments with 2-mm (X jaw) and 5-mm (Y jaw) margin and the same jaw values are applied for all beam angles in the treatment planning system. This additional field gap between the static jaws and the mMLC allows additional radiation dose to normal brain tissue. Because a radiosurgery procedure consists of a single high dose to the planning target volume (PTV), reduction of unnecessary dose to normal brain tissue near the PTV is important, particularly for pediatric patients whose brains are still developing or when a critical organ, such as the optic chiasm, is near the PTV. The purpose of this study was to minimize dose to normal brain tissue by allowing minimal static jaw margin around the mMLC-defined fields and different static jaw values for each beam angle or arc. Dose output factors were measured with various static jaw margins and the results were compared with calculated doses in the treatment planning system. Ten patient plans were randomly selected and recalculated with zero static jaw margins without changing other parameters. Changes of PTV coverage, mean dose to predefined normal brain tissue volume adjacent to PTV, and monitor units were compared. It was found that the dose output percentage difference varied from 4.9-1.3% for the maximum static jaw opening vs. static jaw with zero margins. The mean dose to normal brain tissue at risk adjacent to the PTV was reduced by an average of 1.9%, with negligible PTV coverage loss. This dose reduction strategy may be meaningful in terms of late effects of radiation, particularly in pediatric patients. This study generated clinical knowledge and tools to consistently minimize dose to normal brain tissue.

  12. Carbonaceous aerosols recorded in a southeastern Tibetan glacier: analysis of temporal variations and model estimates of sources and radiative forcing

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Mo; Xu, B.; Cao, J.; Tie, X.; Wang, Hailong; Zhang, Rudong; Qian, Yun; Rasch, Philip J.; Zhao, Shuyu; Wu, Guangjian; et al

    2015-02-02

    High temporal resolution measurements of black carbon (BC) and organic carbon (OC) covering the time period of 1956–2006 in an ice core over the southeastern Tibetan Plateau show a distinct seasonal dependence of BC and OC with higher respective concentrations but a lower OC / BC ratio in the non-monsoon season than during the summer monsoon. We use a global aerosol-climate model, in which BC emitted from different source regions can be explicitly tracked, to quantify BC source–receptor relationships between four Asian source regions and the southeastern Tibetan Plateau as a receptor. The model results show that South Asia hasmore » the largest contribution to the present-day (1996–2005) mean BC deposition at the ice-core drilling site during the non-monsoon season (October to May) (81%) and all year round (74%), followed by East Asia (14% to the non-monsoon mean and 21% to the annual mean). The ice-core record also indicates stable and relatively low BC and OC deposition fluxes from the late 1950s to 1980, followed by an overall increase to recent years. This trend is consistent with the BC and OC emission inventories and the fuel consumption of South Asia (as the primary contributor to annual mean BC deposition). Moreover, the increasing trend of the OC / BC ratio since the early 1990s indicates a growing contribution of coal combustion and/or biomass burning to the emissions. The estimated radiative forcing induced by BC and OC impurities in snow has increased since 1980, suggesting an increasing potential influence of carbonaceous aerosols on the Tibetan glacier melting and the availability of water resources in the surrounding regions. Our study indicates that more attention to OC is merited because of its non-negligible light absorption and the recent rapid increases evident in the ice-core record.« less

  13. Electron density and currents of AlN/GaN high electron mobility transistors with thin GaN/AlN buffer layer

    SciTech Connect (OSTI)

    Bairamis, A.; Zervos, Ch.; Georgakilas, A.; Adikimenakis, A.; Kostopoulos, A.; Kayambaki, M.; Tsagaraki, K.; Konstantinidis, G.

    2014-09-15

    AlN/GaN high electron mobility transistor (HEMT) structures with thin GaN/AlN buffer layer have been analyzed theoretically and experimentally, and the effects of the AlN barrier and GaN buffer layer thicknesses on two-dimensional electron gas (2DEG) density and transport properties have been evaluated. HEMT structures consisting of [300?nm GaN/ 200?nm AlN] buffer layer on sapphire were grown by plasma-assisted molecular beam epitaxy and exhibited a remarkable agreement with the theoretical calculations, suggesting a negligible influence of the crystalline defects that increase near the heteroepitaxial interface. The 2DEG density varied from 6.8??10{sup 12} to 2.1 10{sup 13} cm{sup ?2} as the AlN barrier thickness increased from 2.2 to 4.5?nm, while a 4.5?nm AlN barrier would result to 3.1??10{sup 13} cm{sup ?2} on a GaN buffer layer. The 3.0?nm AlN barrier structure exhibited the highest 2DEG mobility of 900?cm{sup 2}/Vs for a density of 1.3??10{sup 13} cm{sup ?2}. The results were also confirmed by the performance of 1??m gate-length transistors. The scaling of AlN barrier thickness from 1.5?nm to 4.5?nm could modify the drain-source saturation current, for zero gate-source voltage, from zero (normally off condition) to 0.63?A/mm. The maximum drain-source current was 1.1?A/mm for AlN barrier thickness of 3.0?nm and 3.7?nm, and the maximum extrinsic transconductance was 320 mS/mm for 3.0?nm AlN barrier.

  14. Human serum activates CIDEB-mediated lipid droplet enlargement in hepatoma cells

    SciTech Connect (OSTI)

    Singaravelu, Ragunath; National Research Council of Canada, Ottawa, Ontario K1A 0R6 ; Lyn, Rodney K.; National Research Council of Canada, Ottawa, Ontario K1A 0R6 ; Srinivasan, Prashanth; Delcorde, Julie; National Research Council of Canada, Ottawa, Ontario K1A 0R6 ; Steenbergen, Rineke H.; Tyrrell, D. Lorne; Li Ka Shing Institute of Virology, Katz Centre for Pharmacy and Health Research, Edmonton, Alberta T6G 2S2 ; Pezacki, John P.

    2013-11-15

    Highlights: Human serum induced differentiation of hepatoma cells increases cellular lipid droplet (LD) size. The observed increase in LD size correlates with increased PGC-1? and CIDEB expression. Induction of CIDEB expression correlates with rescue of VLDL secretion and loss of ADRP. siRNA knockdown of CIDEB impairs the human serum mediated increase in LD size. This system represents a cost-efficient model to study CIDEBs role in lipid biology. -- Abstract: Human hepatocytes constitutively express the lipid droplet (LD) associated protein cell death-inducing DFFA-like effector B (CIDEB). CIDEB mediates LD fusion, as well as very-low-density lipoprotein (VLDL) maturation. However, there are limited cell culture models readily available to study CIDEBs role in these biological processes, as hepatoma cell lines express negligible levels of CIDEB. Recent work has highlighted the ability of human serum to differentiate hepatoma cells. Herein, we demonstrate that culturing Huh7.5 cells in media supplemented with human serum activates CIDEB expression. This activation occurs through the induced expression of PGC-1?, a positive transcriptional regulator of CIDEB. Coherent anti-Stokes Raman scattering (CARS) microscopy revealed a correlation between CIDEB levels and LD size in human serum treated Huh7.5 cells. Human serum treatment also resulted in a rapid decrease in the levels of adipose differentiation-related protein (ADRP). Furthermore, individual overexpression of CIDEB was sufficient to down-regulate ADRP protein levels. siRNA knockdown of CIDEB revealed that the human serum mediated increase in LD size was CIDEB-dependent. Overall, our work highlights CIDEBs role in LD fusion, and presents a new model system to study the PGC-1?/CIDEB pathways role in LD dynamics and the VLDL pathway.

  15. SU-E-I-63: Quantitative Evaluation of the Effects of Orthopedic Metal Artifact Reduction (OMAR) Software On CT Images for Radiotherapy Simulation

    SciTech Connect (OSTI)

    Jani, S [Sharp Memorial Hospital, San Diego, CA (United States)

    2014-06-01

    Purpose: CT simulation for patients with metal implants can often be challenging due to artifacts that obscure tumor/target delineation and normal organ definition. Our objective was to evaluate the effectiveness of Orthopedic Metal Artifact Reduction (OMAR), a commercially available software, in reducing metal-induced artifacts and its effect on computed dose during treatment planning. Methods: CT images of water surrounding metallic cylindrical rods made of aluminum, copper and iron were studied in terms of Hounsfield Units (HU) spread. Metal-induced artifacts were characterized in terms of HU/Volume Histogram (HVH) using the Pinnacle treatment planning system. Effects of OMAR on enhancing our ability to delineate organs on CT and subsequent dose computation were examined in nine (9) patients with hip implants and two (2) patients with breast tissue expanders. Results: Our study characterized water at 1000 HU with a standard deviation (SD) of about 20 HU. The HVHs allowed us to evaluate how the presence of metal changed the HU spread. For example, introducing a 2.54 cm diameter copper rod in water increased the SD in HU of the surrounding water from 20 to 209, representing an increase in artifacts. Subsequent use of OMAR brought the SD down to 78. Aluminum produced least artifacts whereas Iron showed largest amount of artifacts. In general, an increase in kVp and mA during CT scanning showed better effectiveness of OMAR in reducing artifacts. Our dose analysis showed that some isodose contours shifted by several mm with OMAR but infrequently and were nonsignificant in planning process. Computed volumes of various dose levels showed <2% change. Conclusions: In our experience, OMAR software greatly reduced the metal-induced CT artifacts for the majority of patients with implants, thereby improving our ability to delineate tumor and surrounding organs. OMAR had a clinically negligible effect on computed dose within tissues. Partially funded by unrestricted educational grant from Philips.

  16. HST Rotational Spectral Mapping Of Two L-Type Brown Dwarfs: Variability In And Out Of Water Bands Indicates High-Altitude Haze Layers

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yang, Hao; Apai, Dániel; Marley, Mark S.; Saumon, Didier; Morley, Caroline V.; Buenzli, Esther; Artigau, Étienne; Radigan, Jacqueline; Metchev, Stanimir; Burgasser, Adam J.; et al

    2014-12-17

    We present time-resolved near-infrared spectroscopy of two L5 dwarfs, 2MASS J18212815+1414010 and 2MASS J15074759-1627386, observed with the Wide Field Camera 3 instrument on the Hubble Space Telescope (HST). We study the wavelength dependence of rotation-modulated flux variations between 1.1 μm and 1.7 μm. We find that the water absorption bands of the two L5 dwarfs at 1.15 μm and 1.4 μm vary at similar amplitudes as the adjacent continuum. This differs from the results of previous HST observations of L/T transition dwarfs, in which the water absorption at 1.4 μm displays variations of about half of the amplitude at othermore » wavelengths. We find that the relative amplitude of flux variability out of the water band with respect to that in the water band shows a increasing trend from the L5 dwarfs toward the early T dwarfs. We utilize the models of Saumon & Marley (2008) and find that the observed variability of the L5 dwarfs can be explained by the presence of spatially varying high-altitude haze layers above the condensate clouds. Therefore, our observations show that the heterogeneity of haze layers - the driver of the variability - must be located at very low pressures, where even the water opacity is negligible. In the near future, the rotational spectral mapping technique could be utilized for other atomic and molecular species to probe different pressure levels in the atmospheres of brown dwarfs and exoplanets and uncover both horizontal and vertical cloud structures.« less

  17. An improved criterion for new particle formation in diverse environments

    SciTech Connect (OSTI)

    Kuang, C.; Riipinen, I.; Sihto, S.-L.; Kulmala, M.; McCormick, A.; McMurry, P.

    2010-03-15

    A dimensionless theory for new particle formation (NPF) was developed, using an aerosol population balance model incorporating recent developments in nucleation rates and measured particle growth rates. Based on this theoretical analysis, it was shown that a dimensionless parameter Lg, characterizing the ratio of the particle scavenging loss rate to the particle growth rate, exclusively determined whether or not NPF would occur on a particular day. This parameter determines the probability that a nucleated particle will grow to a detectable size before being lost by coagulation with the pre-existing aerosol. Cluster-cluster coagulation was shown to contribute negligibly to this survival probability under conditions pertinent to the atmosphere. Data acquired during intensive measurement campaigns in Tecamac (MILAGRO), Atlanta (ANARChE), Boulder, and Hyytiala (QUEST II, QUEST IV, and EUCAARI) were used to test the validity of Lg as an NPF criterion. Measurements included aerosol size distributions down to 3 nm and gas-phase sulfuric acid concentrations. The model was applied to 77 NPF events and 19 non-events (characterized by growth of pre-existing aerosol without NPF) measured in diverse environments with broad ranges in sulfuric acid concentrations, ultrafine number concentrations, aerosol surface areas, and particle growth rates (nearly two orders of magnitude). Across this diverse data set, a nominal value of Lg = 0.7 was found to determine the boundary for the occurrence of NPF, with NPF occurring when Lg < 0.7 and being suppressed when Lg > 0.7. Moreover, nearly 45% of measured Lg values associated with NPF fell in the relatively narrow range of 0.1 < Lg < 0.3.

  18. The influence of the iron content on the reductive decomposition of A{sub 3?x}Fe{sub x}Al{sub 2}Si{sub 3}O{sub 12} garnets (A = Mg, Mn; 0.47 ? x ? 2.85)

    SciTech Connect (OSTI)

    Aparicio, Claudia, E-mail: claudia.aparicio@upol.cz; Filip, Jan, E-mail: claudia.aparicio@upol.cz; Mashlan, Miroslav, E-mail: claudia.aparicio@upol.cz; Zboril, Radek, E-mail: claudia.aparicio@upol.cz [Regional Centre of Advanced Technologies and Materials, Departments of Experimental Physics and Physical Chemistry, Faculty of Science, Palacky University, 17. listopadu 1192/12, 77146 Olomouc (Czech Republic)

    2014-10-27

    Thermally-induced reductive decomposition of natural iron-bearing garnets of the almandine-pyrope and almandine-spessartine series were studied at temperatures up to 1200 C (heating rate of 10 C/min) under atmosphere of forming gas (10% of H{sub 2} in N{sub 2}). Crystallochemical formula of the studied garnet was calculated as {sup VIII}(A{sub 3?x}Fe{sub x}{sup 2+}){sup VI}(Al,Fe{sup 3+}){sub 2}Si{sub 3}O{sub 12}, where the amount of Fe{sup 3+} in the octahedral sites is negligible with the exception of pyrope, A = Mg, Mn, and 0.47 ? x ? 2.85. The observed decomposition temperature, determined from differential scanning calorimetry and thermogravimetry, is greater than 1000 C in all cases and showed almost linear dependence on the iron content in the dodecahedral sites of the studied garnets, with the exception of garnet with a near-pyrope composition (Prp{sub 80}Alm{sub 20}). The initial garnet samples and decomposition products were characterized in details by means of X-ray powder diffraction and {sup 57}Fe Mssbauer spectroscopy. We found that all studied garnets have common decomposition products such as metallic iron (in general, rounded particles below 4 ?m) and Fe-spinel; the other identified decomposition products depend on starting chemical composition of the garnet: Fe-cordierite, olivine (fayalite or tephroite), cristobalite, pyroxene (enstatite or pigeonite), and anorthite. Anorthite and pigeonite were only present in garnets with Ca in the dodecahedral site. All the identified phases were usually well crystallized.

  19. Neutralizing Carbonic Acid in Deep Carbonate Strata below the North Atlantic

    SciTech Connect (OSTI)

    Klaus Lackner; Charles Harvey; Bruce Watson

    2008-01-14

    Carbon dioxide injection into deep sea sediments below 2700 m water depth and a few hundred meters to fifteen hundred meters deep in the sediment column may provide permanent geologic storage by gravitational trapping. At high pressures and low temperatures common in deep sea sediments a few hundred meters below sea floor, CO{sub 2} will be in its liquid phase and will be denser than the overlying pore fluid. The lower density of the pore fluid provides a cap to the denser CO{sub 2} and ensures gravitational trapping in the short term. The overall storage capacity for CO{sub 2} in such deep sea formations below the ocean floor is primarily determined by the permeability, and will vary with seafloor depth, geothermal gradient, porosity, and pore water salinity. Furthermore, the dissemination of the injected CO{sub 2} in the sediments and potential chemical reactions between CO{sub 2}, pore fluid and sediments will define its fate in the storage reservoir. The main objectives of our research was to evaluate the potential for sub-seabed CO{sub 2} storage in deep sea sediments using a range of approaches including experiments, permeability analysis, and modeling. Over the course of the three-year award, our results support an important role for sub-seabed storage in a diverse portfolio of carbons sequestration options. Our analysis has shown the feasibility of this type of storage, and also emphasizes that escape or leakage from such sites would be negligible. The most difficult challenge is to overcome the low permeability of typical deep-sea sediments, and a variety of approaches are suggested for future research.

  20. SAFETY AT FLUOR HANFORD (A) CASE STUDY - PREPARED BY THUNDERBIRD SCHOOL OF GLOBAL MANAGEMENT

    SciTech Connect (OSTI)

    ARNOLD LD

    2009-09-25

    By November of 1997, Fluor Hanford (Fluor) had been the site manager of the Hanford nuclear reservation for a year. The Hanford site had been established as part of the Manhattan Project in the 1940s that gave birth to the atomic bomb. Hanford produced two thirds of U.S. plutonium during the Cold War period. The Hanford site was half the size of Rhode Island and occupied 586 square miles in southeastern Washington State. The production of plutonium for more than 40 years left a huge legacy of chemical and radiological contamination: 80 square miles of contaminated groundwater; 2,300 tons of spent nuclear fuel stored in underwater basins; 20 tons of plutonium-laced contaminated materials; and 500 contaminated facilities. The cleanup involved a challenging combination of radioactive material handling within an infrastructure constructed in the 1940s and 1950s. The cleanup that began in 1988 was expected to take 30 years or more. Improving safety at Hanford had already proven to be a significant challenge. As the new site manager at Hanford, Fluor Hanford inherited lower- and mid-level managers and thousands of unionized employees, many of whom were second or third generation Hanford employees. These employees had seen many contractors come and go over the years. Some of the managers who had worked with the previous contractor saw Fluor's emphasis on safety as getting in the way of operations. Union-management relations were fractious. Hanford's culture was described as 'production driven-management told everyone what to do, and, if you didn't do it, there were consequences'. Worker involvement in designing and implementing safety programs was negligible. Fluor Hanford also was having trouble satisfying its client, the Department of Energy (DOE). The DOE did not see a clear path forward for performance improvements at Hanford. Clearly, major change was necessary, but how and where should it be implemented?