Sample records for vapor-phase diffusion mechanisms

  1. Enhanced Vapor-Phase Diffusion in Porous Media - LDRD Final Report

    SciTech Connect (OSTI)

    Ho, C.K.; Webb, S.W.

    1999-01-01T23:59:59.000Z

    As part of the Laboratory-Directed Research and Development (LDRD) Program at Sandia National Laboratories, an investigation into the existence of enhanced vapor-phase diffusion (EVD) in porous media has been conducted. A thorough literature review was initially performed across multiple disciplines (soil science and engineering), and based on this review, the existence of EVD was found to be questionable. As a result, modeling and experiments were initiated to investigate the existence of EVD. In this LDRD, the first mechanistic model of EVD was developed which demonstrated the mechanisms responsible for EVD. The first direct measurements of EVD have also been conducted at multiple scales. Measurements have been made at the pore scale, in a two- dimensional network as represented by a fracture aperture, and in a porous medium. Significant enhancement of vapor-phase transport relative to Fickian diffusion was measured in all cases. The modeling and experimental results provide additional mechanisms for EVD beyond those presented by the generally accepted model of Philip and deVries (1957), which required a thermal gradient for EVD to exist. Modeling and experimental results show significant enhancement under isothermal conditions. Application of EVD to vapor transport in the near-surface vadose zone show a significant variation between no enhancement, the model of Philip and deVries, and the present results. Based on this information, the model of Philip and deVries may need to be modified, and additional studies are recommended.

  2. Assessment of radionuclide vapor-phase transport in unsaturated tuff

    SciTech Connect (OSTI)

    Smith, D.M.; Updegraff, C.D.; Bonano, E.J.; Randall, J.D.

    1986-11-01T23:59:59.000Z

    This report describes bounding calculations performed to investigate the possibility of radionuclide migration in a vapor phase associated with the emplacement of high-level waste canister in unsaturated tuff formations. Two potential radionuclide transport mechanisms in the vapor phase were examined: aerosol migration and convection/diffusion of volatile species. The former may have significant impact on the release of radionuclides to the accessible environment as the concentration in the aerosols will be equal to that in the ground water. A conservative analysis of air diffusion in a stagnant liquid film indicated that for all expected repository conditions, aerosol formation is not possible. The migration of volatile species was examined both in the vicinity of a waste canister and outside the thermally disturbed zone. Two-dimensional (radial) and three-dimensional (radial-vertical) coupled heat transfer-gas flow-liquid flow simulations were performed using the TOUGH computer code. The gas flow rate relative to the liquid flow rate predicted from the simulations allowed calculations of mobility ratios due to convection which led to the conclusion that, except for the immediate region near the canister, transport in the liquid phase will be dominant for radionuclides heavier than radon. Near the waste canister, iodine transport may also be important in the vapor phase. Bounding calculations for vertical mobility ratios were carried out as a function of saturation. These calculations are conservative and agree well with the two-dimensional simulations. Based on this analysis, it is clear that vapor-phase transport will not be important for radionuclides such as cesium and heavier species. Vapor transport for iodine may play a role in the overall release scenario depending on the particular repository conditions.

  3. COMBINED THEORETICAL AND EXPERIMENTAL INVESTIGATION OF MECHANISMS AND KINETICS OF VAPOR-PHASE MERCURY UPTAKE BY CARBONACOUES SURFACES

    SciTech Connect (OSTI)

    Radisav D. Vidic

    2002-05-01T23:59:59.000Z

    The first part of this study evaluated the application of a versatile optical technique to study the adsorption and desorption of model adsorbates representative of volatile polar (acetone) and non-polar (propane) organic compounds on a model carbonaceous surface under ultra high vacuum (UHV) conditions. The results showed the strong correlation between optical differential reflectance (ODR) and adsorbate coverage determined by temperature programmed desorption (TPD). ODR technique was proved to be a powerful tool to investigate surface adsorption and desorption from UHV to high pressure conditions. The effects of chemical functionality and surface morphology on the adsorption/desorption behavior of acetone, propane and mercury were investigated for two model carbonaceous surfaces, namely air-cleaved highly oriented pyrolytic graphite (HOPG) and plasma-oxidized HOPG. They can be removed by thermal treatment (> 500 K). The presence of these groups almost completely suppresses propane adsorption at 90K and removal of these groups leads to dramatic increase in adsorption capacity. The amount of acetone adsorbed is independent of surface heat treatment and depends only on total exposure. The effects of morphological heterogeneity is evident for plasma-oxidized HOPG as this substrate provides greater surface area, as well as higher energy binding sites. Mercury adsorption at 100 K on HOPG surfaces with and without chemical functionalities and topological heterogeneity created by plasma oxidation occurs through physisorption. The removal of chemical functionalities from HOPG surface enhances mercury physisorption. Plasma oxidation of HOPG provides additional surface area for mercury adsorption. Mercury adsorption by activated carbon at atmospheric pressure occurs through two distinct mechanisms, physisorption below 348 K and chemisorption above 348 K. No significant impact of oxygen functionalities was observed in the chemisorption region. The key findings of this study open the possibility to apply scientific information obtained from the studies with simple surfaces like HOPG under ideal conditions (UHV) to industrial sorbents under realistic process conditions. HOPG surface can be modified chemically and topologically by plasma oxidation to simulate key features of activated carbon adsorbents.

  4. Vapor phase modifiers for oxidative coupling

    DOE Patents [OSTI]

    Warren, Barbara K. (Charleston, WV)

    1991-01-01T23:59:59.000Z

    Volatilized metal compounds retard vapor phase alkane conversion reactions in oxidative coupling processes that convert lower alkanes to higher hydrocarbons.

  5. Vapor phase modifiers for oxidative coupling

    DOE Patents [OSTI]

    Warren, B.K.

    1991-12-17T23:59:59.000Z

    Volatilized metal compounds are described which are capable of retarding vapor phase alkane conversion reactions in oxidative coupling processes that convert lower alkanes to higher hydrocarbons.

  6. Quantitative Infrared Intensity Studies of Vapor-PhaseGlyoxal...

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

    Infrared Intensity Studies of Vapor-Phase Glyoxal,Methylglyoxal, and 2,3-Butanedione (Diacetyl) with Quantitative Infrared Intensity Studies of Vapor-Phase Glyoxal,Methylglyoxal,...

  7. Absolute integrated intensities of vapor-phase hydrogen peroxide...

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

    Absolute integrated intensities of vapor-phase hydrogen peroxide (H202) in the mid-infrared at atmospheric pressure. Absolute integrated intensities of vapor-phase hydrogen...

  8. Vapor-phase heat-transport system

    SciTech Connect (OSTI)

    Hedstrom, J.C.

    1983-01-01T23:59:59.000Z

    A vapor-phase heat-transport system is being tested in one of the passive test cells at Los Alamos. The system consists of one selective-surface collector and a condenser inside a water storage tank. The refrigerant, R-11, can be returned to the collector by gravity or with a pump. Results from several operating configurations are presented, together with a comparison with other passive systems. A new self-pumping concept is presented.

  9. The control of confined vapor phase explosions

    SciTech Connect (OSTI)

    Scilly, N.F. [Laporte plc, Widnes (United Kingdom); Owen, O.J.R. [Fine Organics, Ltd., Middlesborough (United Kingdom); Wilberforce, J.K. [Solvay SA, Brussels (Belgium)

    1995-12-31T23:59:59.000Z

    The probability of, for example, a fire or explosion occurring during a process operation is related both to the fire-related properties of the materials used, such as flash point, flammable limits etc., i.e. the material or intrinsic factors, and the nature of the operation and the equipment used, i.e. the extrinsic factors. The risk, or frequency of occurrence, of other hazards such as reaction runaway, major toxic release etc. can be determined in a similar manner. For a vapor phase explosion (and a fire) the probability of the event is the product of the probability of generating a flammable atmosphere and the probability of ignition. Firstly, materials may be coded using properties that are relevant to the hazard in question. Secondly, different operations have different degrees of risk and these risks are assigned as Low, Medium, High etc. according to criteria outlined here. Combination of these two factors will then be a measure of the overall risk of the operation with the specified material and may be used to define operating standards. Currently, the hazard/risk of a vapor phase explosions is examined by this method but in due course dust explosions, fires, condensed phase explosions, reaction runaways, physical explosions, major toxic releases and incompatibility will be included.

  10. Monitoring of vapor phase polycyclic aromatic hydrocarbons

    DOE Patents [OSTI]

    Vo-Dinh, Tuan; Hajaligol, Mohammad R.

    2004-06-01T23:59:59.000Z

    An apparatus for monitoring vapor phase polycyclic aromatic hydrocarbons in a high-temperature environment has an excitation source producing electromagnetic radiation, an optical path having an optical probe optically communicating the electromagnetic radiation received at a proximal end to a distal end, a spectrometer or polychromator, a detector, and a positioner coupled to the first optical path. The positioner can slidably move the distal end of the optical probe to maintain the distal end position with respect to an area of a material undergoing combustion. The emitted wavelength can be directed to a detector in a single optical probe 180.degree. backscattered configuration, in a dual optical probe 180.degree. backscattered configuration or in a dual optical probe 90.degree. side scattered configuration. The apparatus can be used to monitor an emitted wavelength of energy from a polycyclic aromatic hydrocarbon as it fluoresces in a high temperature environment.

  11. Preliminary assessment of halogenated alkanes as vapor-phase tracers

    SciTech Connect (OSTI)

    Adams, Michael C.; Moore, Joseph N.; Hirtz, Paul

    1991-01-01T23:59:59.000Z

    New tracers are needed to evaluate the efficiency of injection strategies in vapor-dominated environments. One group of compounds that seems to meet the requirements for vapor-phase tracing are the halogenated alkanes (HCFCs). HCFCs are generally nontoxic, and extrapolation of tabulated thermodynamic data indicate that they will be thermally stable and nonreactive in a geothermal environment. The solubilities and stabilities of these compounds, which form several homologous series, vary according to the substituent ratios of fluorine, chlorine, and hydrogen. Laboratory and field tests that will further define the suitability of HCFCs as vapor-phase tracers are under way.

  12. MEMS Lubrication by In-Situ Tribochemical Reactions From the Vapor Phase.

    SciTech Connect (OSTI)

    Dugger, Michael T.; Asay, David B.; Kim, Seong H.

    2008-01-01T23:59:59.000Z

    Vapor Phase Lubrication (VPL) of silicon surfaces with pentanol has been demonstrated. Two potential show stoppers with respect to application of this approach to real MEMS devices have been investigated. Water vapor was found to reduce the effectiveness of VPL with alcohol for a given alcohol concentration, but the basic reaction mechanism observed in water-free environments is still active, and devices operated much longer in mixed alcohol and water vapor environments than with chemisorbed monolayer lubricants alone. Complex MEMS gear trains were successfully lubricated with alcohol vapors, resulting in a factor of 104 improvement in operating life without failure. Complex devices could be made to fail if operated at much higher frequencies than previously used, and there is some evidence that the observed failure is due to accumulation of reaction products at deeply buried interfaces. However, if hypothetical reaction mechanisms involving heated surfaces are valid, then the failures observed at high frequency may not be relevant to operation at normal frequencies. Therefore, this work demonstrates that VPL is a viable approach for complex MEMS devices in conventional packages. Further study of the VPL reaction mechanisms are recommended so that the vapor composition may be optimized for low friction and for different substrate materials with potential application to conventionally fabricated, metal alloy parts in weapons systems. Reaction kinetics should be studied to define effective lubrication regimes as a function of the partial pressure of the vapor phase constituent, interfacial shear rate, substrate composition, and temperature.

  13. Liquid-phase compositions from vapor-phase analyses

    SciTech Connect (OSTI)

    Davis, W. Jr. (Oak Ridge Gaseous Diffusion Plant, TN (USA)); Cochran, H.D. (Oak Ridge National Lab., TN (USA))

    1990-02-01T23:59:59.000Z

    Arsenic normally is not considered to be a contaminant. However, because arsenic was found in many cylinders of UF{sub 6}, including in corrosion products, a study was performed of the distribution of the two arsenic fluorides, AsF{sub 3} and AsF{sub 5}, between liquid and vapor phases. The results of the study pertain to condensation or vaporization of liquid UF{sub 6}. This study includes use of various experimental data plus many extrapolations necessitated by the meagerness of the experimental data. The results of this study provide additional support for the vapor-liquid equilibrium model of J.M. Prausnitz and his coworkers as a means of describing the distribution of various impurities between vapor and liquid phases of UF{sub 6}. Thus, it is concluded that AsF{sub 3} will tend to concentrate in the liquid phase but that the concentration of AsF{sub 5} in the vapor phase will exceed its liquid-phase concentration by a factor of about 7.5, which is in agreement with experimental data. Because the weight of the liquid phase in a condensation operation may be in the range of thousands of times that of the vapor phase, most of any AsF{sub 5} will be in the liquid phase in spite of this separation factor of 7.5. It may also be concluded that any arsenic fluorides fed into a uranium isotope separation plant will either travel with other low-molecular-weight gases or react with materials present in the plant. 25 refs., 3 figs., 6 tabs.

  14. Vapor phase elemental sulfur amendment for sequestering mercury in contaminated soil

    DOE Patents [OSTI]

    Looney, Brian B.; Denham, Miles E.; Jackson, Dennis G.

    2014-07-08T23:59:59.000Z

    The process of treating elemental mercury within the soil is provided by introducing into the soil a heated vapor phase of elemental sulfur. As the vapor phase of elemental sulfur cools, sulfur is precipitated within the soil and then reacts with any elemental mercury thereby producing a reaction product that is less hazardous than elemental mercury.

  15. Photoresponse properties of large-area MoS{sub 2} atomic layer synthesized by vapor phase deposition

    SciTech Connect (OSTI)

    Luo, Siwei; Qi, Xiang, E-mail: xqi@xtu.edu.cn, E-mail: jxzhong@xtu.edu.cn; Ren, Long; Hao, Guolin; Fan, Yinping; Liu, Yundan; Han, Weijia; Zang, Chen; Li, Jun; Zhong, Jianxin, E-mail: xqi@xtu.edu.cn, E-mail: jxzhong@xtu.edu.cn [Hunan Key Laboratory for Micro-Nano Energy Materials and Devices, People's Republic of China Laboratory for Quantum Engineering and Micro-Nano Energy Technology, and Faculty of Materials and Optoelectronic Physics, Xiangtan University, Hunan 411105 (China)

    2014-10-28T23:59:59.000Z

    Photoresponse properties of a large area MoS{sub 2} atomic layer synthesized by vapor phase deposition method without any catalyst are studied. Scanning electron microscopy, atomic force microscopy, Raman spectrum, and photoluminescence spectrum characterizations confirm that the two-dimensional microstructures of MoS{sub 2} atomic layer are of high quality. Photoelectrical results indicate that the as-prepared MoS{sub 2} devices have an excellent sensitivity and a good reproducibility as a photodetector, which is proposed to be ascribed to the potential-assisted charge separation mechanism.

  16. The particulate and vapor phase components of airborne polyaromatic hydrocarbons (PAHs) in coal gasification pilot plants

    E-Print Network [OSTI]

    Brink, Eric Jon

    1980-01-01T23:59:59.000Z

    THE PARTICULATE AND VAPOR PHASE COMPONENTS OF AIRBORNE POLYAROMATIC HYDROCARBONS(PAHs) IN COAL GASIFICATION PILOT PLANTS A Thesis by ERIC JON BRINK Submitted to the Graduate College of Texas A & M University in partial fulfillment... of the requirement for the degree of MASTER OF SCIENCE December 1980 Major Subject: Industrial Hygiene THE PARTICULATE AND VAPOR PHASE COMPONENTS OF AIRBORNE POLYAROMATIC HYDROCARBONS (PAHs) IN COAL GASIFICATION PILOT PLANTS A Thesis by ERIC JON BRINK...

  17. DIFFUSION MECHANISMS FOR MULTIMEDIA BROADCASTING IN MOBILE AD HOC NETWORKS

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    DIFFUSION MECHANISMS FOR MULTIMEDIA BROADCASTING IN MOBILE AD HOC NETWORKS E. Baccelli Hitachi HSAL: Philippe.Jacquet@inria.fr ABSTRACT Scarce bandwidth and interferences in mobile ad-hoc networks yield in view to gain enough performance and allow applications such as multimedia diffusion in an ad hoc

  18. Aluminum Nitride Micro-Channels Grown via Metal Organic Vapor Phase Epitaxy for MEMs Applications

    SciTech Connect (OSTI)

    Rodak, L.E.; Kuchibhatla, S.; Famouri, P.; Ting, L.; Korakakis, D.

    2008-01-01T23:59:59.000Z

    Aluminum nitride (AlN) is a promising material for a number of applications due to its temperature and chemical stability. Furthermore, AlN maintains its piezoelectric properties at higher temperatures than more commonly used materials, such as Lead Zirconate Titanate (PZT) [1, 2], making AlN attractive for high temperature micro and nanoelectromechanical (MEMs and NEMs) applications including, but not limited to, high temperature sensors and actuators, micro-channels for fuel cell applications, and micromechanical resonators. This work presents a novel AlN micro-channel fabrication technique using Metal Organic Vapor Phase Epitaxy (MOVPE). AlN easily nucleates on dielectric surfaces due to the large sticking coefficient and short diffusion length of the aluminum species resulting in a high quality polycrystalline growth on typical mask materials, such as silicon dioxide and silicon nitride [3,4]. The fabrication process introduced involves partially masking a substrate with a silicon dioxide striped pattern and then growing AlN via MOVPE simultaneously on the dielectric mask and exposed substrate. A buffered oxide etch is then used to remove the underlying silicon dioxide and leave a free standing AlN micro-channel. The width of the channel has been varied from 5 ìm to 110 ìm and the height of the air gap from 130 nm to 800 nm indicating the stability of the structure. Furthermore, this versatile process has been performed on (111) silicon, c-plane sapphire, and gallium nitride epilayers on sapphire substrates. Reflection High Energy Electron Diffraction (RHEED), Atomic Force Microscopy (AFM), and Raman measurements have been taken on channels grown on each substrate and indicate that the substrate is influencing the growth of the AlN micro-channels on the SiO2 sacrificial layer.

  19. Sulfur Impregnation on Activated Carbon Fibers through H2S Oxidation for Vapor Phase

    E-Print Network [OSTI]

    Borguet, Eric

    Sulfur Impregnation on Activated Carbon Fibers through H2S Oxidation for Vapor Phase Mercury: Sulfur was impregnated onto activated carbon fibers ACFs through H2S oxidation catalyzed by the sorbent CE Database subject headings: Activated carbon; Sulfur; Mercury; Hydrogen sulfides; Oxidation

  20. Vapor phase deposition of oligo,,phenylene ethynylene... molecules for use in molecular electronic devices

    E-Print Network [OSTI]

    Bean, John C.

    , many groups have made headway fab- ricating molecular electronic test devices.1­18 These devices exceptions,22,23 the field of mo- lecular electronics is plagued by problems including a lack of deviceVapor phase deposition of oligo,,phenylene ethynylene... molecules for use in molecular electronic

  1. Sulfurization of a carbon surface for vapor phase mercury removal II: Sulfur forms and mercury uptake

    E-Print Network [OSTI]

    Borguet, Eric

    promote the formation of organic sulfur and the presence of H2S during the cooling process increased in the presence of H2S was very effective towards Hg uptake in nitrogen. Corre- lation of mercury uptake capacitySulfurization of a carbon surface for vapor phase mercury removal ­ II: Sulfur forms and mercury

  2. Substrate effect on CdTe layers grown by metalorganic vapor phase N. V. Sochinskiia),b)

    E-Print Network [OSTI]

    Viña, Luis

    Substrate effect on CdTe layers grown by metalorganic vapor phase epitaxy N. V. Sochinskiia for publication 30 December 1996 CdTe layers were grown by metalorganic vapor phase epitaxy MOVPE on different substrates like sapphire, GaAs, and CdTe wafers. The growth was carried out at the temperature 340 °C

  3. In situ, subsurface monitoring of vapor-phase TCE using fiber optics

    SciTech Connect (OSTI)

    Rossabi, J. [Westinghouse Savannah River Co., Aiken, SC (United States); Colston, B. Jr.; Brown, S.; Milanovich, F. [Lawrence Livermore National Lab., CA (United States); Lee, L.T. Jr. [Army Engineer Waterways Experiment Station, Vicksburg, MS (United States). Geotechnical Lab.

    1993-03-05T23:59:59.000Z

    A vapor-phase, reagent-based, fiber optic trichloroethylene (TCE) sensor developed by Lawrence Livermore National Laboratory (LLNL) was demonstrated at the Savannah River Site (SRS) in two configurations. The first incorporated the sensor into a down-well instrument bounded by two inflatable packers capable of sealing an area for discrete depth analysis. The second involved an integration of the sensor into the probe tip of the Army Corps of Engineers Waterways Experiment Station (WES) cone penetrometry system. Discrete depth measurements of vapor-phase concentrations of TCE in the vadose zone were successfully made using both configurations. These measurements demonstrate the first successful in situ sensing (as opposed to sampling) of TCE at a field site.

  4. Mechanical reaction-diffusion model for bacterial population dynamics

    E-Print Network [OSTI]

    Ngamsaad, Waipot

    2015-01-01T23:59:59.000Z

    The effect of mechanical interaction between cells on the spreading of bacterial population was investigated in one-dimensional space. A nonlinear reaction-diffusion equation has been formulated as a model for this dynamics. In this model, the bacterial cells are treated as the rod-like particles that interact, when contacting each other, through the hard-core repulsion. The repulsion introduces the exclusion process that causes the fast diffusion in bacterial population at high density. The propagation of the bacterial density as the traveling wave front in long time behavior has been analyzed. The analytical result reveals that the front speed is enhanced by the exclusion process---and its value depends on the packing fraction of cell. The numerical solutions of the model have been solved to confirm this prediction.

  5. A description of the vapor phase in the lithium thionyl chloride battery

    E-Print Network [OSTI]

    Morales, Rodolfo

    1988-01-01T23:59:59.000Z

    A DESCRIPTION OF TIIE YAPOP, PHASE IN THF. LITHIUM THIONYI. CHLORIDE BATTERY A Thesis by RODOLFO MORALES, JR. Submitted to the Graduate College of Texas AEzM University in partial fulfrHment of the requirement for the degree oi' MASTER... OF SCIENCE August 1988 Major Subject: Chemical Engineering A DESCRIPTION OF THE VAPOR PHASE IN THE LITHIUM THIONYL CHLORIDE BATTERY A Thesis bv RODOLFO 'vIORALES, JR. Approved as to style and content by: Ralph E. White (Chairman of Committee) James...

  6. Lithium diffusion mechanisms in layered intercalation compounds A. Van der Ven*

    E-Print Network [OSTI]

    Ceder, Gerbrand

    Lithium diffusion mechanisms in layered intercalation compounds A. Van der Ven* , G. Ceder; accepted 28 December 2000 Abstract We investigate the mechanisms of lithium diffusion in layered intercalation compounds from ®rst-principles. We focus on LixCoO2 and ®nd that lithium diffusion

  7. Stippling the skin: Generation of anatomical periodicity by reaction-diffusion mechanisms 

    E-Print Network [OSTI]

    Headon, Denis J.; Painter, Kevin J.

    2009-01-01T23:59:59.000Z

    and ultimately generates an appropriately proportioned anatomy. Here we place reaction-diffusion mechanisms in the context of general concepts regarding the generation of positional information during development and then focus on these mechanisms as parsimonious...

  8. Hydride vapor phase epitaxy and characterization of high-quality ScN epilayers

    SciTech Connect (OSTI)

    Oshima, Yuichi, E-mail: OSHIMA.Yuichi@nims.go.jp; Víllora, Encarnación G.; Shimamura, Kiyoshi [Environment and Energy Materials Research Division, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2014-04-21T23:59:59.000Z

    The heteroepitaxial growth of ScN films was investigated on various substrates by hydride vapor phase epitaxy (HVPE). Single crystalline mirror-like ScN(100) and ScN(110) layers were successfully deposited on r- and m-plane sapphire substrates, respectively. Homogeneous stoichiometric films (N/Sc ratio 1.01?±?0.10) up to 40??m in thickness were deposited. Their mosaicity drastically improved with increasing the film thickness. The band gap was determined by optical methods to be 2.06?eV. Impurity concentrations including H, C, O, Si, and Cl were investigated through energy dispersive X-ray spectrometry and secondary ion mass spectrometry. As a result, it was found that the presence of impurities was efficiently suppressed in comparison with that of HVPE-grown ScN films reported in the past, which was possible thanks to the home-designed corrosion-free HVPE reactor. Room-temperature Hall measurements indicated that the residual free electron concentrations ranged between 10{sup 18}–10{sup 20}?cm{sup ?3}, which was markedly lower than the reported values. The carrier mobility increased monotonically with the decreasing in carrier concentration, achieving the largest value ever reported, 284?cm{sup 2}?V{sup ?1}?s{sup ?1} at n?=?3.7?×?10{sup 18}?cm{sup ?3}.

  9. Carbon-Supported bimetallic Pd-Fe catalysts for vapor-phase hydrodeoxygenation of guaiacol

    SciTech Connect (OSTI)

    Sun, Junming; Karim, Ayman M.; Zhang, He; Kovarik, Libor; Li, Xiaohong S.; Hensley, Alyssa; McEwen, Jean-Sabin; Wang, Yong

    2013-10-01T23:59:59.000Z

    Abstract Carbon supported metal catalysts (Cu/C, Fe/C, Pd/C, Pt/C, PdFe/C and Ru/C) have been prepared, characterized and tested for vapor-phase hydrodeoxygenation (HDO) of guaiacol (GUA) at atmospheric pressure. Phenol was the major intermediate on all catalysts. Over the noble metal catalysts saturation of the aromatic ring was the major pathway observed at low temperature (250 °C), forming predominantly cyclohexanone and cyclohexanol. Substantial ring opening reaction was observed on Pt/C and Ru/C at higher reaction temperatures (e.g., 350 °C). Base metal catalysts, especially Fe/C, were found to exhibit high HDO activity without ring-saturation or ring-opening with the main products being benzene, phenol along with small amounts of cresol, toluene and trimethylbenzene (TMB). A substantial enhancement in HDO activity was observed on the PdFe/C catalysts. Compared with Fe/C, the yield to oxygen-free aromatic products (i.e., benzene/toluene/TMB) on PdFe/C increased by a factor of four at 350 °C, and by approximately a factor of two (83.2% versus 43.3%) at 450 °C. The enhanced activity of PdFe/C is attributed to the formation of PdFe alloy as evidenced by STEM, EDS and TPR.

  10. Recent progress in GaInAsSb thermophotovoltaics grown by organometallic vapor phase epitaxy

    SciTech Connect (OSTI)

    Wang, C.A.; Choi, H.K.; Oakley, D.C. [Massachusetts Inst. of Tech., Lexington, MA (United States). Lincoln Lab.; Charache, G.W. [Lockheed Martin, Inc., Schenectady, NY (United States)

    1998-06-01T23:59:59.000Z

    Studies on the materials development of Ga{sub 1{minus}x}In{sub x}As{sub y}Sb{sub 1{minus}y} alloys for thermophotovoltaic (TPV) devices are reviewed. Ga{sub 1{minus}x}In{sub x}As{sub y}Sb{sub 1{minus}y} epilayers were grown lattice matched to GaSb substrates by organometallic vapor phase epitaxy (OMVPE) using all organometallic precursors including triethylgallium, trimethylindium, tertiarybutylarsine, and trimethylantimony with diethyltellurium and dimethylzinc as the n- and p-type dopants, respectively. The overall material quality of these alloys depends on growth temperature, In content, V/III ratio, substrate misorientation, and to a lesser extent, growth rate. A mirror-like surface morphology and room temperature photoluminescence (PL) are obtained for GaInAsSb layers with peak emission in the wavelength range between 2 and 2.5 {micro}m. The crystal quality improves for growth temperature decreasing from 575 to 525 C, and with decreasing In content, as based on epilayer surface morphology and low temperature PL spectra. A trend of smaller full width at half-maximum for low temperature PL spectra is observed as the growth rate is increased from 1.5 to 2.5 and 5 {micro}m/h. In general, GaInAsSb layers grown on (100) GaSb substrates with a 6{degree} toward (111)B misorientation exhibited overall better material quality than layers grown on the more standard substrate (100)2{degree} toward (110). Consistent growth of high performance lattice-matched GaInAsSb TPV devices is also demonstrated.

  11. Treatment of Produced Water Using a Surfactant Modified Zeolite/Vapor Phase Bioreactor System

    SciTech Connect (OSTI)

    Lynn E. Katz; Kerry A. Kinney; Robert S. Bowman; Enid J. Sullivan; Soondong Kwon; Elaine B. Darby; Li-Jung Chen; Craig R. Altare

    2006-01-31T23:59:59.000Z

    Co-produced water from the oil and gas industry accounts for a significant waste stream in the United States. Produced waters typically contain a high total dissolved solids content, dissolved organic constituents such as benzene and toluene, an oil and grease component as well as chemicals added during the oil-production process. It has been estimated that a total of 14 billion barrels of produced water were generated in 2002 from onshore operations (Veil, 2004). Although much of this produced water is disposed via reinjection, environmental and cost considerations can make surface discharge of this water a more practical means of disposal. In addition, reinjection is not always a feasible option because of geographic, economic, or regulatory considerations. In these situations, it may be desirable, and often necessary from a regulatory viewpoint, to treat produced water before discharge. It may also be feasible to treat waters that slightly exceed regulatory limits for re-use in arid or drought-prone areas, rather than losing them to reinjection. A previous project conducted under DOE Contract DE-AC26-99BC15221 demonstrated that surfactant modified zeolite (SMZ) represents a potential treatment technology for produced water containing BTEX. Laboratory and field experiments suggest that: (1) sorption of benzene, toluene, ethylbenzene and xylenes (BTEX) to SMZ follows linear isotherms in which sorption increases with increasing solute hydrophobicity; (2) the presence of high salt concentrations substantially increases the capacity of the SMZ for BTEX; (3) competitive sorption among the BTEX compounds is negligible; and, (4) complete recovery of the SMZ sorption capacity for BTEX can be achieved by air sparging the SMZ. This report summarizes research for a follow on project to optimize the regeneration process for multiple sorption/regeneration cycles, and to develop and incorporate a vapor phase bioreactor (VPB) system for treatment of the off-gas generated during air sparging. To this end, we conducted batch and column laboratory SMZ and VPB experiments with synthetic and actual produced waters. Based on the results of the laboratory testing, a pilot scale study was designed and conducted to evaluate the combined SMZ/VPB process. An economic and regulatory feasibility analysis was also completed as part of the current study to assess the viability of the process for various water re-use options.

  12. TREATMENT OF PRODUCED WATERS USING A SURFACTANT MODIFIED ZEOLITE/VAPOR PHASE BIOREATOR SYSTEM

    SciTech Connect (OSTI)

    LYNN E. KATZ; KERRY A. KINNEY; R.S. BOWMAN; E.J. SULLIVAN

    2003-10-01T23:59:59.000Z

    Co-produced water from the oil and gas industry is by some estimates the largest single waste stream in the country, aside from nonhazardous industrial wastes. Characteristics of produced water include high total dissolved solids content, dissolved organic constituents such as benzene and toluene, an oil and grease component, and chemicals added during the oil-production process. While most of the produced water is disposed via reinjection, some of them must be treated to remove organic constituents before the water is discharged. An efficient, cost-effective treatment technology is needed to remove these constituents. Surfactant-modified zeolite (SMZ) has been used successfully to treat contaminated ground water for organic and inorganic constituents. In addition, the low cost of natural zeolites makes their use attractive in water-treatment applications. Our previous DOE research work (DE-AC26-99BC15221) demonstrated that SMZ could successfully remove BTEX compounds from the produced water. In addition, SMZ could be regenerated through a simple air sparging process. The primary goal of this project is to develop a robust SMZ/VPB treatment system to efficiently remove the organic constituents from produced water in a cost-effective manner. This report summarizes work of this project from March 2003 through September 2003. We have continued our investigation of SMZ regeneration from our previous DOE project. Ten saturation/stripping cycles have been completed for SMZ columns saturated with BTEX compounds. The results suggest that BTEX sorption capacity is not lost after ten saturation/regeneration cycles. The composition of produced water from a site operated by Crystal Solutions Ltd. in Wyoming has been characterized and was used to identify key semi-volatile components. Isotherms with selected semi-volatile components have been initiated and preliminary results have been obtained. The experimental vapor phase bioreactors for this project have been designed and assembled to treat the off-gas from the SMZ regeneration process. These columns will be used both in the laboratory and in the proposed field testing to be conducted next year. Innocula for the columns that degrade all of the BTEX columns have been developed.

  13. The ramifications of diffusive volume transport in classical fluid mechanics

    E-Print Network [OSTI]

    Bielenberg, James R. (James Ronald), 1976-

    2004-01-01T23:59:59.000Z

    The thesis that follows consists of a collection of work supporting and extending a novel reformulation of fluid mechanics, wherein the linear momentum per unit mass in a fluid continuum, m, is supposed equal to the volume ...

  14. Effect of atomic scale plasticity on hydrogen diffusion in iron: Quantum mechanically informed and on-the-fly kinetic

    E-Print Network [OSTI]

    Ortiz, Michael

    viewpoints, is futile. Among several mechanisms proposed for hydrogen embrittlement (HE) of metals, hydrogenEffect of atomic scale plasticity on hydrogen diffusion in iron: Quantum mechanically informed-assisted diffusion and trapping of hydrogen by crystalline defects in iron. Given an embedded atom (EAM) potential

  15. ZnO/Cu(InGa)Se2 solar cells prepared by vapor phase Zn doping

    DOE Patents [OSTI]

    Ramanathan, Kannan; Hasoon, Falah S.; Asher, Sarah E.; Dolan, James; Keane, James C.

    2007-02-20T23:59:59.000Z

    A process for making a thin film ZnO/Cu(InGa)Se2 solar cell without depositing a buffer layer and by Zn doping from a vapor phase, comprising: depositing Cu(InGa)Se2 layer on a metal back contact deposited on a glass substrate; heating the Cu(InGa)Se2 layer on the metal back contact on the glass substrate to a temperature range between about 100.degree. C. to about 250.degree. C.; subjecting the heated layer of Cu(InGa)Se2 to an evaporant species from a Zn compound; and sputter depositing ZnO on the Zn compound evaporant species treated layer of Cu(InGa)Se2.

  16. The role of polymer formation during vapor phase lubrication of silicon.

    SciTech Connect (OSTI)

    Dugger, Michael Thomas; Dirk, Shawn M.; Ohlhausen, James Anthony

    2010-10-01T23:59:59.000Z

    The lubrication of silicon surfaces with alcohol vapors has recently been demonstrated. With a sufficient concentration of pentanol vapor present, sliding of a silica ball on an oxidized silicon wafer can proceed with no measurable wear. The initial results of time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis of wear surfaces revealed a reaction product having thickness on the order of a monolayer, and with an ion spectrum that included fragments having molecular weights of 200 or more that occurred only inside the wear tracks. The parent alcohol molecule pentanol, has molecular weight of 88amu, suggesting that reactions of adsorbed alcohols on the wearing surfaces allowed polymerization of the alcohols to form higher molecular weight species. In addition to pin-on-disk studies, lubrication of silicon surfaces with pentanol vapors has also been demonstrated using MicroElectroMechanical Systems (MEMS) devices. Recent investigations of the reaction mechanisms of the alcohol molecules with the oxidized silicon surfaces have shown that wearless sliding requires a concentration of the alcohol vapor that is dependent upon the contact stress during sliding, with higher stress requiring a greater concentration of alcohol. Different vapor precursors including those with acid functionality, olefins, and methyl termination also produce polymeric reaction products, and can lubricate the silica surfaces. Doping the operating environment with oxygen was found to quench the formation of the polymeric reaction product, and demonstrates that polymer formation is not necessary for wearless sliding.

  17. Effects of carbon on phosphorus diffusion in SiGe:C and the implications on phosphorus diffusion mechanisms

    SciTech Connect (OSTI)

    Lin, Yiheng; Xia, Guangrui [Department of Materials Engineering, The University of British Columbia, 309-6350 Stores Rd, Vancouver, British Columbia V6T 1Z4 (Canada); Yasuda, Hiroshi; Wise, Rick [Texas Instruments, 13121 TI Blvd., Dallas, Texas 75243 (United States); Schiekofer, Manfred; Benna, Bernhard [Texas Instruments Deutschland GmbH, Haggertystrasse 1, 85356 Freising (Germany)

    2014-10-14T23:59:59.000Z

    The use of carbon (C) in SiGe base layers is an important approach to control the base layer dopant phosphorus (P) diffusion and thus enhance PNP heterojunction bipolar transistor (HBT) performance. This work quantitatively investigated the carbon impacts on P diffusion in Si{sub 0.82}Ge{sub 0.18}:C and Si:C under rapid thermal anneal conditions. The carbon molar fraction is up to 0.32%. The results showed that the carbon retardation effect on P diffusion is less effective for Si{sub 0.82}Ge{sub 0.18}:C than for Si:C. In Si{sub 0.82}Ge{sub 0.18}:C, there is an optimum carbon content at around 0.05% to 0.1%, beyond which more carbon incorporation does not retard P diffusion any more. This behavior is different from the P diffusion behavior in Si:C and the B in Si:C and low Ge SiGe:C, which can be explained by the decreased interstitial-mediated diffusion fraction f{sub I}{sup P,?SiGe} to 95% as Ge content increases to 18%. Empirical models were established to calculate the time-averaged point defect concentrations and effective diffusivities as a function of carbon and was shown to agree with previous studies on boron, phosphorus, arsenic and antimony diffusion with carbon.

  18. Journal of Light Emitting Diodes Vol 2 N0 1, April 2010 1 Abstract--In metal organic vapor phase epitaxy we developed

    E-Print Network [OSTI]

    Wetzel, Christian M.

    Journal of Light Emitting Diodes Vol 2 N0 1, April 2010 1 Abstract-- In metal organic vapor phase epitaxy we developed GaInN/GaN quantum well material suitable for 500 ­ 580 nm light emitting diodes at longer wavelengths. Index Terms-- a-plane GaN, GaInN, Green light emitting diode, m-plane GaN I

  19. Verification of the integrity of barriers using gas diffusion

    SciTech Connect (OSTI)

    Ward, D.B. [SPECTRA Research Inst., Albuquerque, NM (United States); Williams, C.V. [Sandia National Labs., Albuquerque, NM (United States). Environmental Restoration Technologies Dept.

    1997-06-01T23:59:59.000Z

    In-situ barrier materials and designs are being developed for containment of high risk contamination as an alternative to immediate removal or remediation. The intent of these designs is to prevent the movement of contaminants in either the liquid or vapor phase by long-term containment, essentially buying time until the contaminant depletes naturally or a remediation can be implemented. The integrity of the resultant soil-binder mixture is typically assessed by a number of destructive laboratory tests (leaching, compressive strength, mechanical stability with respect to wetting and freeze-thaw cycles) which as a group are used to infer the likelihood of favorable long-term performance of the barrier. The need exists for a minimally intrusive yet quantifiable methods for assessment of a barrier`s integrity after emplacement, and monitoring of the barrier`s performance over its lifetime. Here, the authors evaluate non-destructive measurements of inert-gas diffusion (specifically, SF{sub 6}) as an indicator of waste-form integrity. The goals of this project are to show that diffusivity can be measured in core samples of soil jet-grouted with Portland cement, validate the experimental method through measurements on samples, and to calculate aqueous diffusivities from a series of diffusion measurements. This study shows that it is practical to measure SF{sub 6} diffusion rates in the laboratory on samples of grout (Portland cement and soil) typical of what might be used in a barrier. Diffusion of SF{sub 6} through grout (Portland cement and soil) is at least an order of magnitude slower than through air. The use of this tracer should be sensitive to the presence of fractures, voids, or other discontinuities in the grout/soil structure. Field-scale measurements should be practical on time-scales of a few days.

  20. Turbulent mixing, viscosity, diffusion and gravity in the formation of cosmological structures: the fluid mechanics of dark matter

    E-Print Network [OSTI]

    Carl H. Gibson

    2000-12-18T23:59:59.000Z

    Self-gravitational structure formation theory for astrophysics and cosmology is revised using nonlinear fluid mechanics. Gibson's 1996-2000 theory balances fluid mechanical forces with gravitational forces and density diffusion with gravitational diffusion at critical viscous, turbulent, magnetic, and diffusion length scales termed Schwarz scales. Instability occurs for scales larger than the largest Schwarz scale rather than only for scales larger than the acoustic scale introduced by Jeans 1902. From the new theory, the inner-halo-dark-matter of galaxies consists of dark proto-globular-star-cluster (PGC) clumps of small-planetary-mass objects called primordial fog particles (PFPs) formed soon after decoupling at 300,000 years. PFPs explain Schild's 1996 "rogue planets >... likely to be the missing mass" of a quasar lens-galaxy. WIMP dark matter fluid is super-diffusive and fragments at large L_SD scales to form outer-galaxy-halos. In the beginning of structure formation 30,000 years after the Big Bang the viscous Schwarz scale L_SV matched the horizon scale L_H at proto-galaxy-supercluster masses, decreasing to proto-galaxy fragments at 300,000 years. WIMP diffusivities from observed outer-halo (L_SD) scales indicate WIMP particle masses in the neutrino rather than neutralino range.

  1. Energy and Momentum Conservation for Diffusion - A Stochastic Mechanics Approximation - Part I

    E-Print Network [OSTI]

    Johan Beumee

    2006-10-19T23:59:59.000Z

    This paper models the classical diffusion of a main particle through a heatbath by means of a pre-limit microscopic representation of its drifted momentum and energy transfers at collision times. The collision point linear interpolated path can be approximated by the solution to the "inscribed" continuous stochastic differential equation using the same drift function. Employing results from stochastic mechanics it is then shown that the combined main particle/heatbath system does not exchange or radiate energy if the probability distribution for the position of the main particle is derived from Schroedinger's equation. Furthermore it is shown that the main particle distance traveled between collisions and the mean inter-collision time must satisfy a type of Minkowski invariant. Hence if there is a correlation between the pre- and post-collision velocities of the main particle through a collision point then the mean distance traveled can be related to the mean inter-particle collision times via a Lorentz transformation. The last Section shows that this approach can be applied to all elastic main particle/heatbath particle collisions either via direct calculation involving modeling the collision scattering or by altering the properties of the heatbath.

  2. X-ray determination of threading dislocation densities in GaN/Al{sub 2}O{sub 3}(0001) films grown by metalorganic vapor phase epitaxy

    SciTech Connect (OSTI)

    Kopp, Viktor S., E-mail: victor.kopp@pdi-berlin.de; Kaganer, Vladimir M. [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin (Germany); Baidakova, Marina V.; Lundin, Wsevolod V.; Nikolaev, Andrey E.; Verkhovtceva, Elena V.; Yagovkina, Maria A. [Ioffe Physical-Technical Institute of the Russian Academy of Sciences, Politekhnicheskaya 26, 194021 St.-Petersburg (Russian Federation); Cherkashin, Nikolay [CEMES-CNRS and Université de Toulouse, 29 rue J. Marvig, 31055 Toulouse (France)

    2014-02-21T23:59:59.000Z

    Densities of a- and a+c-type threading dislocations for a series of GaN films grown in different modes by metalorganic vapor phase epitaxy are determined from the x-ray diffraction profiles in skew geometry. The reciprocal space maps are also studied. Theory of x-ray scattering from crystals with dislocations is extended in order to take into account contribution from both threading and misfit dislocations. The broadening of the reciprocal space maps along the surface normal and the rotation of the intensity distribution ellipse is attributed to misfit dislocations at the interface. We find that the presence of a sharp AlN/GaN interface leads to an ordering of misfit dislocations and reduces strain inhomogeneity in GaN films.

  3. Preparation of Ag Schottky contacts on n-type GaN bulk crystals grown in nitrogen rich atmosphere by the hydride vapor phase epitaxy technique

    SciTech Connect (OSTI)

    Stübner, R., E-mail: ronald.stuebner@physik.tu-dresden.de; Kolkovsky, Vl.; Weber, J. [Technische Universität Dresden, 01062 Dresden (Germany); Leibiger, Gunnar; Habel, Frank [Freiberger Compound Materials GmbH, 09599 Freiberg (Germany)

    2014-10-14T23:59:59.000Z

    Electrical properties of Schottky contacts on n-type GaN grown in nitrogen rich atmosphere with different N/Ga ratios by hydride vapor phase epitaxy were investigated. We show that tunneling of electrons from the conduction band of GaN to the metal is dominant in our samples. The quality of Schottky contacts does not only depend on surface preparation but also on the growth conditions of the crystals. Schottky contacts on these crystals show an increasing deterioration when higher N/Ga growth ratios are used. We correlate our results with the presence of negatively charged gallium vacancies in the samples. These charges compensate the positively charged donors and lead to a significant increase in series resistance.

  4. Microstructure and mechanical properties of diffusion bonded W/steel joint using V/Ni composite interlayer

    SciTech Connect (OSTI)

    Liu, W.S.; Cai, Q.S., E-mail: cai2009pm@163.com; Ma, Y.Z.; Wang, Y.Y.; Liu, H.Y.; Li, D.X.

    2013-12-15T23:59:59.000Z

    Diffusion bonding between W and steel using V/Ni composite interlayer was carried out in vacuum at 1050 °C and 10 MPa for 1 h. The microstructural examination and mechanical property evaluation of the joints show that the bonding of W to steel was successful. No intermetallic compound was observed at the steel/Ni and V/W interfaces for the joints bonded. The electron probe microanalysis and X-ray diffraction analysis revealed that Ni{sub 3}V, Ni{sub 2}V, Ni{sub 2}V{sub 3} and NiV{sub 3} were formed at the Ni/V interface. The tensile strength of about 362 MPa was obtained for as-bonded W/steel joint and the failure occurred at W near the V/W interface. The nano-indentation test across the joining interfaces demonstrated the effect of solid solution strengthening and intermetallic compound formation in the diffusion zone. - Highlights: • Diffusion bonding of W to steel was realized using V/Ni composite interlayer. • The interfacial microstructure of the joint was clarified. • Several V–Ni intermetallic compounds were formed in the interface region. • The application of V/Ni composite interlayer improved the joining quality.

  5. Turbulent mixing, diffusion and gravity in the formation of cosmological structures: the fluid mechanics of dark matter

    E-Print Network [OSTI]

    Carl H. Gibson

    1999-04-18T23:59:59.000Z

    The theory of gravitational structure formation in astrophysics and cosmology is revised based on real fluid behavior and turbulent mixing theory. Gibson's 1996-1998 theory balances fluid mechanical forces with gravitational forces and density diffusivity with gravitational diffusivity at critical viscous, turbulent, magnetic, and diffusion length scales termed Schwarz scales L_SX. Condensation and void formation occurs on non-acoustic density nuclei produced by turbulent mixing for scales L>=L_SXmax rather than on sound wave crests and troughs for L>=L_J as required by Jeans's 1902 linear acoustic theory. Schwarz scales L_SX = L_SV, L_ST, L_SM, or L_SD may be smaller or larger than Jeans's scale L_J. Thus, a very different "nonlinear" cosmology emerges to replace the currently accepted "linear" cosmology. According to the new theory, most of the inner halo dark matter of galaxies consists of planetary mass objects that formed soon after the plasma to neutral gas transition 300,000 years after the Big Bang. These objects are termed primordial fog particles (PFPs) and provide an explanation for Schild's 1996 "rogue planets ... likely to be the missing mass" of his observed quasar-lens galaxy, inferred from the twinkling frequencies of both quasar images and their phased difference.

  6. Organometallic Vapor Phase Epitaxy of n-GaSb and n-GaInAsSb for Low Resistance Ohmic Contacts

    SciTech Connect (OSTI)

    C.A. Wang; D.A. Shiau; R.K. Huang; C.T. Harris; M.K. Connors

    2003-07-10T23:59:59.000Z

    A comparison of n-GaSb and n-GaInAsSb epilayers for ohmic contacts in GaSb-based devices is studied. The epilayers were grown by organometallic vapor phase epitaxy and doped with Te. At similar electron concentrations, the atomic Te concentration, as determined by secondary ion mass spectroscopy, is more than 2 times higher in n-GaSb compared to n-GaInAsSb. In addition, the electron mobility is lower in n-GaSb than n-GaInAsSb at similar electron concentrations. The electron concentration saturates at about 1.3 x 10{sup 18} cm{sup -3} for n-GaSb, but linearly increases for n-GaInAsSb. Pd/Ge/Au/Pt/Au metallization was studied for ohmic contacts. A specific contact resistivity of 1 x 10{sup -5}{Omega}-cm{sup 2} for n-GaSb was measured. The specific contact resistivity can be greatly improved by contacting n-GaInAsSb, and a significantly lower specific contact resistivity of 2 x 10{sup -6} {Omega}-cm{sup 2} for n-GaInAsSb was measured.

  7. Density functional theory study of the mechanism of Li diffusion in rutile RuO{sub 2}

    SciTech Connect (OSTI)

    Jung, Jongboo; Cho, Maenghyo [WCU Program on Multiscale Mechanical Design, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)] [WCU Program on Multiscale Mechanical Design, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); Zhou, Min, E-mail: min.zhou@gatech.edu [WCU Program on Multiscale Mechanical Design, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of) [WCU Program on Multiscale Mechanical Design, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); George W. Woodruff School of Mechanical Engineering, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States)

    2014-01-15T23:59:59.000Z

    First-principle calculations are carried out to study the diffusion of Li ions in rutile structure RuO{sub 2}, a material for positive electrodes in rechargeable Li ion batteries. The calculations focus on migration pathways and energy barriers for diffusion in Li-poor and Li-rich phases using the Nudged Elastic Band Method. Diffusion coefficients estimated based on calculated energy barriers are in good agreement with experimental values reported in the literature. The results confirm the anisotropic nature of diffusion of Li ions in one-dimensional c channels along the [001] crystalline direction of rutile RuO{sub 2} and show that Li diffusion in the Li-poor phase is faster than in the Li-rich phase. The findings of fast Li diffusion and feasible Li insertion at low temperatures in the host rutile RuO{sub 2} suggest this material is a good ionic conductor for Li transport. The finding also suggests possible means for enhancing the performance of RuO{sub 2}-based electrode materials.

  8. Charge transport properties of p-CdTe/n-CdTe/n{sup +}-Si diode-type nuclear radiation detectors based on metalorganic vapor-phase epitaxy-grown epilayers

    SciTech Connect (OSTI)

    Niraula, M.; Yasuda, K.; Wajima, Y.; Yamashita, H.; Tsukamoto, Y.; Suzuki, Y.; Matsumoto, M.; Takai, N.; Tsukamoto, Y.; Agata, Y. [Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555 (Japan)] [Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555 (Japan)

    2013-10-28T23:59:59.000Z

    Charge transport properties of p-CdTe/n-CdTe/n{sup +}-Si diode-type nuclear radiation detectors, fabricated by growing p-and n-type CdTe epilayers on (211) n{sup +}-Si substrates using metalorganic vapor-phase epitaxy (MOVPE), were studied by analyzing current-voltage characteristics measured at various temperatures. The diode fabricated shows good rectification properties, however, both forward and reverse biased currents deviate from their ideal behavior. The forward current exhibits typical feature of multi-step tunneling at lower biases; however, becomes space charge limited type when the bias is increased. On the other hand, the reverse current exhibits thermally activated tunneling-type current. It was found that trapping centers at the p-CdTe/n-CdTe junction, which were formed due to the growth induced defects, determine the currents of this diode, and hence limit the performance of the nuclear radiation detectors developed.

  9. Ge-related faceting and segregation during the growth of metastable (GaAs){sub 1{minus}x}(Ge{sub 2}){sub x} alloy layers by metal{endash}organic vapor-phase epitaxy

    SciTech Connect (OSTI)

    Norman, A.G.; Olson, J.M.; Geisz, J.F.; Moutinho, H.R.; Mason, A.; Al-Jassim, M.M. [National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401 (United States)] [National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401 (United States); Vernon, S.M. [Spire Corporation, One Patriots Park, Bedford, Massachusetts 01730 (United States)] [Spire Corporation, One Patriots Park, Bedford, Massachusetts 01730 (United States)

    1999-03-01T23:59:59.000Z

    (GaAs){sub 1{minus}x}(Ge{sub 2}){sub x} alloy layers, 0{lt}x{lt}0.22, have been grown by metal{endash}organic vapor-phase epitaxy on vicinal (001) GaAs substrates. Transmission electron microscopy revealed pronounced phase separation in these layers, resulting in regions of GaAs-rich zinc-blende and Ge-rich diamond cubic material that appears to lead to substantial band-gap narrowing. For x=0.1 layers, the phase-separated microstructure consisted of intersecting sheets of Ge-rich material on {l_brace}115{r_brace}B planes surrounding cells of GaAs-rich material, with little evidence of antiphase boundaries. Atomic force microscopy revealed {l_brace}115{r_brace}B surface faceting associated with the phase separation. {copyright} {ital 1999 American Institute of Physics.}

  10. DIFFUSION IN SOLIDSDIFFUSION IN SOLIDS FICK'S LAWS

    E-Print Network [OSTI]

    Subramaniam, Anandh

    Diffusion bonding To comprehend many materials related phenomenon one must understand Diffusion. The focusDIFFUSION IN SOLIDSDIFFUSION IN SOLIDS FICK'S LAWS KIRKENDALL EFFECT ATOMIC MECHANISMS Diffusion in Solids P.G. Shewmon McGraw-Hill, New York (1963) #12;Oxidation Roles of Diffusion Creep Aging

  11. Electromagnetic Nature of Thermo-Mechanical Mass-Energy Transfer Due to Photon Diffusive Re-Emission and Propagation

    E-Print Network [OSTI]

    Kostic, Milivoje M.

    and the Physics law of forced interactions will be violated, since these thermo-mechanical phenomena are neither gravitational nor nuclear interactions. Actually, the deficiency of classical Fourier heat conduction theory confirmed in nuclear reaction processes: If a nuclear reaction is carried out in a "sealed" box, then energy

  12. Enforcement Documents - Portsmouth Gaseous Diffusion Plant |...

    Broader source: Energy.gov (indexed) [DOE]

    Gaseous Diffusion Plant March 26, 2010 Enforcement Letter, Geiger Brothers Mechanical Contractors, INC - March 26, 2010 Issued to Geiger Brothers Mechanical Contractors,...

  13. Photoelectric and luminescence properties of GaSb-Based nanoheterostructures with a deep Al(As)Sb/InAsSb/Al(As)Sb quantum well grown by metalorganic vapor-phase epitaxy

    SciTech Connect (OSTI)

    Mikhailova, M. P.; Andreev, I. A., E-mail: igor@iropt9.ioffe.ru; Ivanov, E. V.; Konovalov, G. G.; Grebentshikova, E. A.; Yakovlev, Yu. P. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)] [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Hulicius, E.; Hospodkova, A.; Pangrac, Y. [Academy of Sciences of the Czech Republic, Institute of Physics (Czech Republic)] [Academy of Sciences of the Czech Republic, Institute of Physics (Czech Republic)

    2013-08-15T23:59:59.000Z

    The luminescence and photoelectric properties of heterostructures with a deep Al(As)Sb/InAsSb/Al(As)Sb quantum well grown on n-GaSb substrates by metalorganic vapor-phase epitaxy are investigated. Intense superlinear luminescence and increased optical power as a function of the pump current in the photon energy range of 0.6-0.8 eV are observed at temperatures of T = 77 and 300 K. The photoelectric, current-voltage, and capacitance characteristics of these heterostructures are studied in detail. The photosensitivity is examined with photodetectors operating in the photovoltaic mode in the spectral range of 0.9-2.0 {mu}m. The sensitivity maximum at room temperature is observed at a wavelength of 1.55 {mu}m. The quantum efficiency, detectivity, and response time of the photodetectors were estimated. The quantum efficiency and detectivity at the peak of the photosensitivity spectrum are as high as {eta} = 0.6-0.7 and D{sub {lambda}max}{sup *} = (5-7) Multiplication-Sign 10{sup 10} cm Hz{sup 1/2} W{sup -1}, respectively. The photodiode response time determined as the rise time of the photoresponse pulse from 0.1 to the level 0.9 is 100-200 ps. The photodiode transmission bandwidth is 2-3 GHz. Photodetectors with a deep Al(As)Sb/InAsSb/Al(As)Sb quantum well grown on n-GaSb substrates are promising foruse in heterodyne detection systems and in information technologies.

  14. First-principles studies on vacancy-modified interstitial diffusion mechanism of oxygen in nickel, associated with large-scale atomic simulation techniques

    SciTech Connect (OSTI)

    Fang, H. Z.; Shang, S. L.; Wang, Y.; Liu, Z. K. [National Energy Technology Laboratory Regional University Alliance, U.S. Department of Energy, Pittsburgh, Pennsylvania 15236 (United States); Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Alfonso, D.; Alman, D. E. [National Energy Technology Laboratory Regional University Alliance, U.S. Department of Energy, Pittsburgh, Pennsylvania 15236 (United States); National Energy Technology Laboratory, U.S. Department of Energy, Pittsburgh, Pennsylvania 15236 (United States); Shin, Y. K.; Zou, C. Y.; Duin, A. C. T. van [National Energy Technology Laboratory Regional University Alliance, U.S. Department of Energy, Pittsburgh, Pennsylvania 15236 (United States); Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Lei, Y. K.; Wang, G. F. [National Energy Technology Laboratory Regional University Alliance, U.S. Department of Energy, Pittsburgh, Pennsylvania 15236 (United States); Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pennsylvania 15261 (United States)

    2014-01-28T23:59:59.000Z

    This paper is concerned with the prediction of oxygen diffusivities in fcc nickel from first-principles calculations and large-scale atomic simulations. Considering only the interstitial octahedral to tetrahedral to octahedral minimum energy pathway for oxygen diffusion in fcc lattice, greatly underestimates the migration barrier and overestimates the diffusivities by several orders of magnitude. The results indicate that vacancies in the Ni-lattice significantly impact the migration barrier of oxygen in nickel. Incorporation of the effect of vacancies results in predicted diffusivities consistent with available experimental data. First-principles calculations show that at high temperatures the vacancy concentration is comparable to the oxygen solubility, and there is a strong binding energy and a redistribution of charge density between the oxygen atom and vacancy. Consequently, there is a strong attraction between the oxygen and vacancy in the Ni lattice, which impacts diffusion.

  15. Microviscometric studies on thermal diffusion

    E-Print Network [OSTI]

    Reyna, Eddie

    2012-06-07T23:59:59.000Z

    HICROVISCKStTRIC STUDIES THERMAL DIFFUSION A Thesis Eddie Reyfls Submitted to the Grsducte School of the Agricultursl sfld Mechanical College of Texas in partisl fulfillment of the requireeeflts far the degree of MASTER OF SCIENCE August... microliter samples to 1'/ reproduceability, This equipment is used to observe the thermal diffusion effects of polystyrene in toluene solutions in c 01uslus-Dickel thermal diffusion column. An inversion in the values of concentration and molecular veight...

  16. {l_brace}311{r_brace} Defects in ion-implanted silicon: The cause of transient diffusion, and a mechanism for dislocation formation

    SciTech Connect (OSTI)

    Eaglesham, D.J.; Stolk, P.A.; Cheng, J.Y.; Gossmann, H.J.; Poate, J.M. [AT and T Bell Labs., Murray Hill, NJ (United States); Haynes, T.E. [Oak Ridge National Lab., TN (United States). Solid State Div.

    1995-04-01T23:59:59.000Z

    Ion implantation is used at several critical stages of Si integrated circuit manufacturing. The authors show how {l_brace}311{r_brace} defects arising after implantation are responsible for both enhanced dopant diffusion during annealing, and stable dislocations post-anneal. They observe {l_brace}311{r_brace} defects in the earliest stages of an anneal. They subsequently undergo rapid Ostwald ripening and evaporation. At low implant doses evaporation dominates, and they can quantitatively relate the interstitials emitted from these defects to the transient enhancement in diffusivity of dopants such as B and P. At higher doses Ostwald ripening is significant, and they observe the defects to undergo a series of unfaulting reactions to form both Frank loops and perfect dislocations. They demonstrate the ability to control both diffusion and dislocations by the addition of small amounts of carbon impurities.

  17. EK424 THERMODYNAMICS AND STATISTICAL MECHANICS (Fall 2013) Thermodynamics is the study of processes (e.g., expansion of a gas, boiling of water, or diffusion

    E-Print Network [OSTI]

    Vajda, Sandor

    EK424 THERMODYNAMICS AND STATISTICAL MECHANICS (Fall 2013) Thermodynamics is the study in order to take place? We will study the thermodynamics of two types of processes: mechanical, or the chemical conversion of glucose into useful work), and a good understanding of thermodynamics is essential

  18. EK424 THERMODYNAMICS AND STATISTICAL MECHANICS (Spring 2013) Thermodynamics is the study of processes (e.g., expansion of a gas, boiling of water, or diffusion

    E-Print Network [OSTI]

    Vajda, Sandor

    EK424 THERMODYNAMICS AND STATISTICAL MECHANICS (Spring 2013) Thermodynamics is the study in order to take place? We will study the thermodynamics of two types of processes: mechanical, or the chemical conversion of glucose into useful work), and a good understanding of thermodynamics is essential

  19. Moisture Diffusion in Asphalt Binders and Fine Aggregate Mixtures

    E-Print Network [OSTI]

    Vasconcelos, Kamilla L.

    2011-08-08T23:59:59.000Z

    cost in highway maintenance and vehicle operations. One key mechanism of how moisture reaches the asphalt-aggregate interface is by its permeation or diffusion through the asphalt binder or mastic. Different techniques are available for diffusion...

  20. Is Arnold diffusion relevant to global diffusion?

    E-Print Network [OSTI]

    Seiichiro Honjo; Kunihiko Kaneko

    2003-07-27T23:59:59.000Z

    Global diffusion of Hamiltonian dynamical systems is investigated by using a coupled standard maps. Arnold web is visualized in the frequency space, using local rotation numbers, while Arnold diffusion and resonance overlaps are distinguished by the residence time distributions at resonance layers. Global diffusion in the phase space is shown to be accelerated by diffusion across overlapped resonances generated by the coupling term, rather than Arnold diffusion along the lower-order resonances. The former plays roles of hubs for transport in the phase space, and accelerate the diffusion.

  1. Diffusive limit for the random Lorentz gas

    E-Print Network [OSTI]

    Alessia Nota

    2014-10-14T23:59:59.000Z

    We review some recent results concerning the derivation of the diffusion equation and the validation of Fick's law for the microscopic model given by the random Lorentz Gas. These results are achieved by using a linear kinetic equation as an intermediate level of description between our original mechanical system and the diffusion equation.

  2. Parallel flow diffusion battery

    DOE Patents [OSTI]

    Yeh, H.C.; Cheng, Y.S.

    1984-01-01T23:59:59.000Z

    A parallel flow diffusion battery for determining the mass distribution of an aerosol has a plurality of diffusion cells mounted in parallel to an aerosol stream, each diffusion cell including a stack of mesh wire screens of different density.

  3. High-efficiency solar cells fabricated from direct-current magnetron sputtered n-indium tin oxide onto p-InP grown by atmospheric pressure metalorganic vapor phase epitaxy

    SciTech Connect (OSTI)

    Li, X.; Wanlass, M.W.; Gessert, T.A.; Emery, K.A.; Coutts, T.J.

    1989-05-01T23:59:59.000Z

    Solar cells based on dc magnetron sputtered indium tin oxide onto epitaxially grown films of p-InP have been fabricated and analyzed. The best cells had a global efficiency of 18.4% and an air mass zero (AMO) efficiency of 16.0%. The principal fabrication variable considered was the constituency of the sputtering gas and both argon/hydrogen and argon/oxygen mixtures have been used. The former cells have the higher efficiencies, are apparently stable, and exhibit almost ideal junction characteristics. The latter cells are relatively unstable and exhibit much higher ideality factors and reverse saturation current densities. The temperature dependence of the reverse saturation current indicates totally different charge transfer mechanisms in the two cases.

  4. Microfabricated diffusion source

    DOE Patents [OSTI]

    Oborny, Michael C. (Albuquerque, NM); Frye-Mason, Gregory C. (Cedar Crest, NM); Manginell, Ronald P. (Albuquerque, NM)

    2008-07-15T23:59:59.000Z

    A microfabricated diffusion source to provide for a controlled diffusion rate of a vapor comprises a porous reservoir formed in a substrate that can be filled with a liquid, a headspace cavity for evaporation of the vapor therein, a diffusion channel to provide a controlled diffusion of the vapor, and an outlet to release the vapor into a gas stream. The microfabricated diffusion source can provide a calibration standard for a microanalytical system. The microanalytical system with an integral diffusion source can be fabricated with microelectromechanical systems technologies.

  5. Surveying Diffusion in Complex Geometries. An Essay

    E-Print Network [OSTI]

    Grebenkov, Denis

    2009-01-01T23:59:59.000Z

    The surrounding world surprises us by the beauty and variety of complex shapes that emerge from nanometric to macroscopic scales. Natural or manufactured materials (sandstones, sedimentary rocks and cement), colloidal solutions (proteins and DNA), biological cells, tissues and organs (lungs, kidneys and placenta), they all present irregularly shaped "scenes" for a fundamental transport "performance", that is, diffusion. Here, the geometrical complexity, entangled with the stochastic character of diffusive motion, results in numerous fascinating and sometimes unexpected effects like diffusion screening or localization. These effects control many diffusion-mediated processes that play an important role in heterogeneous catalysis, biochemical mechanisms, electrochemistry, growth phenomena, oil recovery, or building industry. In spite of a long and rich history of academic and industrial research in this field, it is striking to see how little we know about diffusion in complex geometries, especially the one whic...

  6. Creep effects in diffusion bonding of oxygen-free copper

    E-Print Network [OSTI]

    Moilanen, Antti

    Diffusion is the transport of atoms or particles through the surrounding material. Various microstructural changes in metals are based on the diffusion phenomena. In solid metals the diffusion is closely related to crystallographic defects. In single-component metals the dominant mechanism of diffusion is the vacancy mechanism. Diffusion bonding is a direct technological application of diffusion. It is an advanced solidstate joining process in which the surfaces of two components are brought to contact with each other and heated under a pressing load in a controlled environment. During the process, the contact surfaces are bonded by atomic diffusion across the interface and as a result, one solid piece is formed. The condition of high temperature and low applied stress combined with relatively long process duration enables the creep effects to take place in bonded metals. Furthermore, creep causes unwanted permanent deformations in the bonded components. Some authors suggest that there could be a threshold fo...

  7. Surveying Diffusion in Complex Geometries. An Essay

    E-Print Network [OSTI]

    Denis Grebenkov

    2009-09-08T23:59:59.000Z

    The surrounding world surprises us by the beauty and variety of complex shapes that emerge from nanometric to macroscopic scales. Natural or manufactured materials (sandstones, sedimentary rocks and cement), colloidal solutions (proteins and DNA), biological cells, tissues and organs (lungs, kidneys and placenta), they all present irregularly shaped "scenes" for a fundamental transport "performance", that is, diffusion. Here, the geometrical complexity, entangled with the stochastic character of diffusive motion, results in numerous fascinating and sometimes unexpected effects like diffusion screening or localization. These effects control many diffusion-mediated processes that play an important role in heterogeneous catalysis, biochemical mechanisms, electrochemistry, growth phenomena, oil recovery, or building industry. In spite of a long and rich history of academic and industrial research in this field, it is striking to see how little we know about diffusion in complex geometries, especially the one which occurs in three dimensions. We present our recent results on restricted diffusion. We look into the role of geometrical complexity at different levels, from boundary microroughness to hierarchical structure and connectivity of the whole diffusion-confining domain. We develop a new approach which consists in combining fast random walk algorithms with spectral tools. The main focus is on studying diffusion in model complex geometries (von Koch boundaries, Kitaoka acinus, etc.), as well as on developing and testing spectral methods. We aim at extending this knowledge and at applying the accomplished arsenal of theoretical and numerical tools to structures found in nature and industry.

  8. Organic lateral heterojunction devices for vapor-phase chemical detection

    E-Print Network [OSTI]

    Ho, John C., 1980-

    2009-01-01T23:59:59.000Z

    As the U.S. is engaged in battle overseas, there is an urgent need for the development of sensors for early warning and protection of military forces against potential attacks. On the battlefields, improvised explosive ...

  9. MODELLING AND SIMULATION OF LIQUID-VAPOR PHASE TRANSITION

    E-Print Network [OSTI]

    Faccanoni, Gloria

    Generator Turbine Generator Cooling Tower Condenser Cooling Water Pump Reactor Core Reactor Vessel Control and Steam (secondary loop) Water (cooling loop) Pump Steam Generator Turbine Generator Cooling Tower Water pressurized (primary loop) Water and Steam (secondary loop) Water (cooling loop) Pump Steam

  10. Quantitative Infrared Intensity Studies of Vapor-Phase

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 -

  11. MULTISCALE MODELING OF DIFFUSION-INDUCED DEFORMATION PROCESSES

    E-Print Network [OSTI]

    Ponce, V. Miguel

    MULTISCALE MODELING OF DIFFUSION- INDUCED DEFORMATION PROCESSES Dr. Eugene Olevsky Friday, February 19, 2010 Engineering Bldg. Room E 300 Sintering is a high temperature process of bonding together of matter transport by different diffusion mechanisms driven by the high surface energy of aggregates

  12. Tungsten diffusion in silicon

    SciTech Connect (OSTI)

    De Luca, A.; Texier, M.; Burle, N.; Oison, V.; Pichaud, B. [Aix-Marseille Université, IM2NP UMR 7334, Faculté des Sciences et Techniques, Campus de Saint-Jérôme, Avenue Escadrille Normandie Niemen - Case 142, F-13397 Marseille Cedex (France); Portavoce, A., E-mail: alain.portavoce@im2np.fr [CNRS, IM2NP UMR 7334, Faculté des Sciences et Techniques, Campus de Saint-Jérôme, Avenue Escadrille Normandie Niemen - Case 142, F-13397 Marseille Cedex (France); Grosjean, C. [STMicroelectronics, Rousset (France)

    2014-01-07T23:59:59.000Z

    Two doses (10{sup 13} and 10{sup 15}?cm{sup ?2}) of tungsten (W) atoms were implanted in different Si(001) wafers in order to study W diffusion in Si. The samples were annealed or oxidized at temperatures between 776 and 960?°C. The diffusion profiles were measured by secondary ion mass spectrometry, and defect formation was studied by transmission electron microscopy and atom probe tomography. W is shown to reduce Si recrystallization after implantation and to exhibit, in the temperature range investigated, a solubility limit close to 0.15%–0.2%, which is higher than the solubility limit of usual metallic impurities in Si. W diffusion exhibits unusual linear diffusion profiles with a maximum concentration always located at the Si surface, slower kinetics than other metals in Si, and promotes vacancy accumulation close to the Si surface, with the formation of hollow cavities in the case of the higher W dose. In addition, Si self-interstitial injection during oxidation is shown to promote W-Si clustering. Taking into account these observations, a diffusion model based on the simultaneous diffusion of interstitial W atoms and W-Si atomic pairs is proposed since usual models used to model diffusion of metallic impurities and dopants in Si cannot reproduce experimental observations.

  13. Nonlinear friction in quantum mechanics

    E-Print Network [OSTI]

    Roumen Tsekov

    2010-03-01T23:59:59.000Z

    The effect of nonlinear friction forces in quantum mechanics is studied via dissipative Madelung hydrodynamics. A new thermo-quantum diffusion equation is derived, which is solved for the particular case of quantum Brownian motion with a cubic friction. It is extended also by a chemical reaction term to describe quantum reaction-diffusion systems with nonlinear friction as well.

  14. Adaptive multigroup radiation diffusion

    E-Print Network [OSTI]

    Williams, Richard B., Sc. D. Massachusetts Institute of Technology

    2005-01-01T23:59:59.000Z

    This thesis describes the development and implementation of an algorithm for dramatically increasing the accuracy and reliability of multigroup radiation diffusion simulations at low group counts. This is achieved by ...

  15. Diffusion Maps for Changing Data Diffusion Maps for Changing Data

    E-Print Network [OSTI]

    Hirn, Matthew

    Diffusion Maps for Changing Data Diffusion Maps for Changing Data Matthew J. Hirn Department;Diffusion Maps for Changing Data Collaborators Ronald Coifman (Yale University) Roy Lederman (Yale University) #12;Diffusion Maps for Changing Data How to compare images across sensors? Figure: Sokolov Mine

  16. Diffusion Maps for Changing Data Diffusion Maps for Changing Data

    E-Print Network [OSTI]

    Hirn, Matthew

    Diffusion Maps for Changing Data Diffusion Maps for Changing Data Matthew J. Hirn Department of Mathematics Yale University July 26, 2012 Bell Labs #12;Diffusion Maps for Changing Data Collaborators Joint work with Ronald Coifman and Roy Lederman. #12;Diffusion Maps for Changing Data Overview 1 High

  17. Diffusion Maps for Changing Data Diffusion Maps for Changing Data

    E-Print Network [OSTI]

    Hirn, Matthew

    Diffusion Maps for Changing Data Diffusion Maps for Changing Data Matthew J. Hirn Department of Mathematics Yale University November 29, 2012 Kansas State University Colloquium #12;Diffusion Maps;Diffusion Maps for Changing Data How to compare images across sensors? Figure: Sokolov Mine in 2009 and 2010

  18. Diffusion Maps for Changing Data Diffusion Maps for Changing Data

    E-Print Network [OSTI]

    Hirn, Matthew

    Diffusion Maps for Changing Data Diffusion Maps for Changing Data Matthew J. Hirn Department in Honor of the 70th Birthday of David R. Larson #12;Diffusion Maps for Changing Data Collaborators Joint work with Ronald Coifman and Roy Lederman. #12;Diffusion Maps for Changing Data High Dimensional Data

  19. Diffusion Maps for Changing Data Diffusion Maps for Changing Data

    E-Print Network [OSTI]

    Hirn, Matthew

    Diffusion Maps for Changing Data Diffusion Maps for Changing Data Matthew J. Hirn September 3, 2013 #12;Diffusion Maps for Changing Data Collaborators Simon Adar, Tel Aviv University Eyal Ben Dor, Tel, Clarkson University Yoel Shkolnisky, Tel Aviv University #12;Diffusion Maps for Changing Data Heat equation

  20. Vacancy Jumps in PdIn: Reconciling Nuclear Relaxation and Diffusion Measurements

    E-Print Network [OSTI]

    Collins, Gary S.

    Vacancy Jumps in PdIn: Reconciling Nuclear Relaxation and Diffusion Measurements Gary S. Collins Keywords: point defect, vacancy, diffusion, defect interaction, intermetallic compound, perturbed angular correlation, PAC, nuclear relaxation, diffusion mechanisms Abstract. Vacancy jump frequencies in PdIn were

  1. Anomalous diffusion modifies solar neutrino fluxes

    E-Print Network [OSTI]

    Kaniadakis, G; Lissia, M; Quarati, P

    1998-01-01T23:59:59.000Z

    Density and temperature conditions in the solar core suggest that the microscopic diffusion of electrons and ions could be nonstandard: diffusion and friction coefficients are energy dependent, collisions are not two-body processes and retain memory beyond the single scattering event. A direct consequence of nonstandard diffusion is that the equilibrium energy distribution of particles departs from the Maxwellian one (tails goes to zero more slowly or faster than exponentially) modifying the reaction rates. This effect is qualitatively different from temperature and/or composition modification: small changes in the number of particles in the distribution tails can strongly modify the rates without affecting bulk properties, such as the sound speed or hydrostatic equilibrium, which depend on the mean values from the distribution. This mechanism can considerably increase the range of predictions for the neutrino fluxes allowed by the current experimental values (cross sections and solar properties) and can be u...

  2. Oxygen diffusion in titanite: Lattice diffusion and fast-path diffusion in single crystals

    E-Print Network [OSTI]

    Watson, E. Bruce

    Oxygen diffusion in titanite: Lattice diffusion and fast-path diffusion in single crystals X June 2006 Editor: P. Deines Abstract Oxygen diffusion in natural and synthetic single-crystal titanite was characterized under both dry and water-present conditions. For the dry experiments, pre-polished titanite

  3. Physical process Mechanical mechanisms

    E-Print Network [OSTI]

    Berlin,Technische Universität

    1 Physical process Generation · Mechanical mechanisms F = m·a · Electric/Magnetic mechanisms F ­ Quadrupoles......shear stress fluctuations ­ High order poles...... phys. interpretation difficult Governing

  4. OXYGEN DIFFUSION IN HYPOSTOICHIOMETRIC URANIUM DIOXIDE

    E-Print Network [OSTI]

    Kim, Kee Chul

    2010-01-01T23:59:59.000Z

    Research Division OXYGEN DIFFUSION IN HYPOSTOICHIOMETRIC11905 -DISCLAIMER - OXYGEN DIFFUSION IN HYPOSTOICHIOMETRICc o n e e n i g woroxygen self-diffusion coefficient

  5. The Impact of Thermal Conductivity and Diffusion Rates on Water Vapor Transport through Gas Diffusion Layers

    E-Print Network [OSTI]

    Burlatsky, S F; Gummallaa, M; Condita, D; Liua, F

    2013-01-01T23:59:59.000Z

    Water management in a hydrogen polymer electrolyte membrane (PEM) fuel cell is critical for performance. The impact of thermal conductivity and water vapor diffusion coefficients in a gas diffusion layer (GDL) has been studied by a mathematical model. The fraction of product water that is removed in the vapour phase through the GDL as a function of GDL properties and operating conditions has been calculated and discussed. Furthermore, the current model enables identification of conditions when condensation occurs in each GDL component and calculation of temperature gradient across the interface between different layers, providing insight into the overall mechanism of water transport in a given cell design. Water transport mode and condensation conditions in the GDL components depend on the combination of water vapor diffusion coefficients and thermal conductivities of the GDL components. Different types of GDL and water removal scenarios have been identified and related to experimentally-determined GDL proper...

  6. Peridynamic thermal diffusion

    SciTech Connect (OSTI)

    Oterkus, Selda [Department of Aerospace and Mechanical Engineering, The University of Arizona, Tucson, AZ 85721 (United States); Madenci, Erdogan, E-mail: madenci@email.arizona.edu [Department of Aerospace and Mechanical Engineering, The University of Arizona, Tucson, AZ 85721 (United States); Agwai, Abigail [Intel Corporation, Chandler, AZ 85226 (United States)

    2014-05-15T23:59:59.000Z

    This study presents the derivation of ordinary state-based peridynamic heat conduction equation based on the Lagrangian formalism. The peridynamic heat conduction parameters are related to those of the classical theory. An explicit time stepping scheme is adopted for numerical solution of various benchmark problems with known solutions. It paves the way for applying the peridynamic theory to other physical fields such as neutronic diffusion and electrical potential distribution.

  7. Electro-diffusion in a plasma with two ion species

    SciTech Connect (OSTI)

    Kagan, Grigory; Tang Xianzhu [Theoretical Division Los Alamos National Laboratory Los Alamos, New Mexico 87545 (United States)

    2012-08-15T23:59:59.000Z

    Electric field is a thermodynamic force that can drive collisional inter-ion-species transport in a multicomponent plasma. In an inertial confinement fusion capsule, such transport causes fuel ion separation even with a target initially prepared to have equal number densities for the two fuel ion species. Unlike the baro-diffusion driven by ion pressure gradient and the thermo-diffusion driven by ion and electron temperature gradients, electro-diffusion has a critical dependence on the charge-to-mass ratio of the ion species. Specifically, it is shown here that electro-diffusion vanishes if the ion species have the same charge-to-mass ratio. An explicit expression for the electro-diffusion ratio is obtained and used to investigate the relative importance of electro- and baro-diffusion mechanisms. In particular, it is found that electro-diffusion reinforces baro-diffusion in the deuterium and tritium mix, but tends to cancel it in the deuterium and helium-3 mix.

  8. Efficiency limits of diffusive shock acceleration

    E-Print Network [OSTI]

    A. Meli; A. Mastichiadis

    2007-08-10T23:59:59.000Z

    It is well accepted today that diffusive acceleration in shocks results to the cosmic ray spectrum formation. This is in principle true for non-relativistic shocks, since there is a detailed theory covering a large range of their properties and the resulting power-law spectrum, which is nevertheless not as efficient to reach the very high energies observed in the cosmic ray spectrum. On the other hand, the cosmic ray maximum energy and the resulting spectra from relativistic shocks, are still under investigation and debate concerning their contribution to the features of the cosmic ray spectrum and the measured, or implied, cosmic ray radiation from candidate astrophysical sources. Here, we discuss the efficiency of the first order Fermi (diffusive) acceleration mechanism up to relativistic shock speeds, presenting Monte Carlo simulations.

  9. Light diffusing fiber optic chamber

    DOE Patents [OSTI]

    Maitland, Duncan J. (Lafayette, CA)

    2002-01-01T23:59:59.000Z

    A light diffusion system for transmitting light to a target area. The light is transmitted in a direction from a proximal end to a distal end by an optical fiber. A diffusing chamber is operatively connected to the optical fiber for transmitting the light from the proximal end to the distal end and transmitting said light to said target area. A plug is operatively connected to the diffusing chamber for increasing the light that is transmitted to the target area.

  10. W. Gregory Sawyer1 Thierry A. Blanchet

    E-Print Network [OSTI]

    Sawyer, Wallace

    , vapor phase lubrication is a candidate approach under extended durations of such extreme condition 1 Engineering and Mechanics, Rensselaer Polytechnic Institute, Troy, NY 12180 Vapor-Phase Lubrication in Combined Rolling and Sliding Contacts: Modeling and Experimentation The in situ vapor-phase lubrication

  11. Turing instability in reaction-diffusion systems with nonlinear diffusion

    SciTech Connect (OSTI)

    Zemskov, E. P., E-mail: zemskov@ccas.ru [Russian Academy of Sciences, Dorodnicyn Computing Center (Russian Federation)

    2013-10-15T23:59:59.000Z

    The Turing instability is studied in two-component reaction-diffusion systems with nonlinear diffusion terms, and the regions in parametric space where Turing patterns can form are determined. The boundaries between super- and subcritical bifurcations are found. Calculations are performed for one-dimensional brusselator and oregonator models.

  12. Anomalous diffusion modifies solar neutrino fluxes

    E-Print Network [OSTI]

    G. Kaniadakis; A. Lavagno; M. Lissia; P. Quarati

    1997-10-16T23:59:59.000Z

    Density and temperature conditions in the solar core suggest that the microscopic diffusion of electrons and ions could be nonstandard: Diffusion and friction coefficients are energy dependent, collisions are not two-body processes and retain memory beyond the single scattering event. A direct consequence of nonstandard diffusion is that the equilibrium energy distribution of particles departs from the Maxwellian one (tails goes to zero more slowly or faster than exponentially) modifying the reaction rates. This effect is qualitatively different from temperature and/or composition modification: Small changes in the number of particles in the distribution tails can strongly modify the rates without affecting bulk properties, such as the sound speed or hydrostatic equilibrium, which depend on the mean values from the distribution. This mechanism can considerably increase the range of predictions for the neutrino fluxes allowed by the current experimental values (cross sections and solar properties) and can be used to reduce the discrepancy between these predictions and the solar neutrino experiments.

  13. BDP: BrainSuite Diffusion Pipeline

    E-Print Network [OSTI]

    Leahy, Richard M.

    BDP: BrainSuite Diffusion Pipeline Chitresh Bhushan #12; Quantify microstructural tissue ROI Connectivity ROI Statistics MPRAGE Diffusion #12;Diffusion Pipeline Dicom to NIfTI Co ROIs Custom ROIs #12;Diffusion Pipeline Dicom to NIfTI Co-registration Diffusion Modeling Tractography

  14. Cage diffusion in liquid mercury Yaspal S. Badyal

    E-Print Network [OSTI]

    Montfrooij, Wouter

    University, Massachusetts 02138, USA Ignatz M. de Schepper Interfaculty Reactor Institute, TU Delft, 2629 JB(q,E). It is believed that cage diffusion plays an important part in the dynamics of real fluids, such as noble gas on the fast short-time decay mechanism of liquid mercury pertinent to cage diffu- sion. Recent neutron

  15. MEMBRANE FUNCTION, Part 2. Passive Movement: Diffusion, Osmosis, and Gibbs-Donnan Equilibrium 1

    E-Print Network [OSTI]

    Prestwich, Ken

    such as ion gradients or sunlight. I. Passive transport Passive transport is diffusion through a membrane of the membrane. This movement is entirely by the process of diffusion (to be covered below) · ions and polar. Mechanisms of Membrane Transport There are two general modes of transport across membranes: passive transport

  16. Portable vapor diffusion coefficient meter

    DOE Patents [OSTI]

    Ho, Clifford K. (Albuquerque, NM)

    2007-06-12T23:59:59.000Z

    An apparatus for measuring the effective vapor diffusion coefficient of a test vapor diffusing through a sample of porous media contained within a test chamber. A chemical sensor measures the time-varying concentration of vapor that has diffused a known distance through the porous media. A data processor contained within the apparatus compares the measured sensor data with analytical predictions of the response curve based on the transient diffusion equation using Fick's Law, iterating on the choice of an effective vapor diffusion coefficient until the difference between the predicted and measured curves is minimized. Optionally, a purge fluid can forced through the porous media, permitting the apparatus to also measure a gas-phase permeability. The apparatus can be made lightweight, self-powered, and portable for use in the field.

  17. Molecular imaging of water binding state and diffusion in breast cancer using diffuse optical spectroscopy and diffusion weighted MRI

    E-Print Network [OSTI]

    Chung, So Hyun; Yu, Hon; Su, Min-Ying; Cerussi, Albert E.; Tromberg, Bruce J.

    2012-01-01T23:59:59.000Z

    Molecular imaging of water binding state and diffusion inChung et al. , “In vivo water state measurements in breastby measuring tis- sue water state using diffuse optical

  18. Diffuser for augmenting a wind turbine

    DOE Patents [OSTI]

    Foreman, Kenneth M. (North Bellmore, NY); Gilbert, Barry L. (Westbury, NY)

    1984-01-01T23:59:59.000Z

    A diffuser for augmenting a wind turbine having means for energizing the boundary layer at several locations along the diffuser walls is improved by the addition of a short collar extending radially outward from the outlet of the diffuser.

  19. Evaluations of nutrient diffusing substrates and the primary importance of light in controlling periphyton

    E-Print Network [OSTI]

    Murawski, Matthew Thomas

    2012-06-07T23:59:59.000Z

    eutrophication. In the first study, artificial channels were used to investigate the response of periphyton to different nutrient delivery mechanisms. In two channels, nutrients were delivered via diffusion to periphyton growth surfaces using modified Matlock...

  20. Effects of turbulent diffusion on the chemistry of diffuse clouds

    E-Print Network [OSTI]

    P. Lesaffre; M. Gerin; P. Hennebelle

    2007-04-24T23:59:59.000Z

    Aims. We probe the effect of turbulent diffusion on the chemistry at the interface between a cold neutral medium (CNM) cloudlet and the warm neutral medium (WNM). Methods. We perform moving grid, multifluid, 1D, hydrodynamical simulations with chemistry including thermal and chemical diffusion. The diffusion coefficients are enhanced to account for turbulent diffusion. We post-process the steady-states of our simulations with a crude model of radiative transfer to compute line profiles. Results. Turbulent diffusion spreads out the transition region between the CNM and the WNM. We find that the CNM slightly expands and heats up: its CH and H$_2$ content decreases due to the lower density. The change of physical conditions and diffusive transport increase the H$^+$ content in the CNM which results in increased OH and H$_2$O. Diffusion transports some CO out of the CNM. It also brings H$_2$ into contact with the warm gas with enhanced production of CH$^+$, H$_3^+$, OH and H$_2$O at the interface. O lines are sensitive to the spread of the thermal profile in the intermediate region between the CNM and the WNM. Enhanced molecular content at the interface of the cloud broadens the molecular line profiles and helps exciting transitions of intermediate energy. The relative molecular yield are found higher for bigger clouds. Conclusions. Turbulent diffusion can be the source of additional molecular production and should be included in chemical models of the interstellar medium (ISM). It also is a good candidate for the interpretation of observational problems such as warm H$_2$, CH$^+$ formation and presence of H$_3^+$.

  1. AMEAerospace & Mechanical

    E-Print Network [OSTI]

    Wang, Hai

    AMEAerospace & Mechanical Engineering #12;Aerospace and Mechanical Engineers design complex mechanical, thermal, fluidic, acousti- cal, optical, and electronic systems, with char- acteristic sizes space. Aerospace and Mechanical Engineering (AME) students conduct basic and applied research within

  2. Hot carrier diffusion in graphene

    E-Print Network [OSTI]

    Ruzicka, Brian Andrew; Wang, Shuai; Werake, Lalani Kumari; Weintrub, Ben; Loh, Kian Ping; Zhao, Hui

    2010-11-01T23:59:59.000Z

    We report an optical study of charge transport in graphene. Diffusion of hot carriers in epitaxial graphene and reduced graphene oxide samples are studied using an ultrafast pump-probe technique with a high spatial resolution. Spatiotemporal...

  3. Cation self-diffusion in Fe/sub 2/O/sub 3/

    SciTech Connect (OSTI)

    Hoshino, K.; Peterson, N.L.

    1984-01-01T23:59:59.000Z

    Self-diffusion of /sup 59/Fe in single crystals of Fe/sub 2/O/sub 3/ parallel to the c-axis has been measured as a function of temperature (1150 to 1340/sup 0/C) and oxygen partial pressure (2 x 10/sup -3/) less than or equal to Po/sub 2/ less than or equal to 1 atm). The oxygen partial pressure dependence of the diffusivity indicates that cation self-diffusion occurs by an interstitial-type mechanism. The simultaneous diffusion of /sup 52/Fe and /sup 59/Fe has been measured in Fe/sub 2/O/sub 3/ at 1251/sup 0/C and Po/sub 2/ = 1.91 x 10/sup -2/ atm. The small value of the isotope effect (f..delta..K = 0.067 +- 0.016) is consistent with diffusion of Fe ions by an interstitially mechanism.

  4. Accelerating and Retarding Anomalous Diffusion

    E-Print Network [OSTI]

    Chai Hok Eab; S. C. Lim

    2012-01-14T23:59:59.000Z

    In this paper Gaussian models of retarded and accelerated anomalous diffusion are considered. Stochastic differential equations of fractional order driven by single or multiple fractional Gaussian noise terms are introduced to describe retarding and accelerating subdiffusion and superdiffusion. Short and long time asymptotic limits of the mean squared displacement of the stochastic processes associated with the solutions of these equations are studied. Specific cases of these equations are shown to provide possible descriptions of retarding or accelerating anomalous diffusion.

  5. Devitrite-based Optical Diffusers

    E-Print Network [OSTI]

    Butt, Haider; Knowles, Kevin M.; Montelongo, Yunuen; Amaratunga, Gehan A. J.; Wilkinson, Timothy D.

    2014-02-21T23:59:59.000Z

    technological use of this devitrification product in soda–lime–silica glasses, in contrast to other inorganic glasses in which controlled devitrification has given rise to the family of materials known as glass-ceramics.5 Here we present data on the inherent... , photovoltaic,9 photolithography,10 and in the health industry for producing diffused therapeutic thermal energy.11 Visual display systems also require diffusers for increasing the field of view; with the emergence of light emitting diodes (LEDs...

  6. Diffusion in confinement as a microscopic relaxation mechanism...

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

    form 27 January 2012 Available online 4 February 2012 a b s t r a c t Using quasielastic neutron scattering, we compare dynamics in single-element liquids, glass-forming selenium...

  7. Modeling gas displacement kinetics in coal with Maxwell-Stefan diffusion theory

    SciTech Connect (OSTI)

    Wei, X.R.; Wang, G.X.; Massarotto, P.; Rudolph, V.; Golding, S.D. [University of Queensland, Brisbane, Qld. (Australia). Division of Chemical Engineering

    2007-12-15T23:59:59.000Z

    The kinetics of binary gas counter-diffusion and Darcy flow in a large coal sample were modeled, and the results compared with data from experimental laboratory investigations. The study aimed for a better understanding of the CO{sub 2}-sequestration enhanced coalbed methane (ECBM) recovery process. The transport model used was based on the bidisperse diffusion mechanism and Maxwell-Stefan (MS) diffusion theory. This provides an alternative approach to simulate multicomponent gas diffusion and flow in bulk coals. A series of high-stress core flush tests were performed on a large coal sample sourced from a Bowen Basin coal mine in Queensland, Australia to investigate the kinetics of one gas displacing another. These experimental results were used to derive gas diffusivities, and to examine the predictive capability of the diffusion model. The simulations show good agreements with the displacement experiments revealing that MS diffusion theory is superior for describing diffusion of mixed gases in coals compared with the constant Fick diffusivity model. The optimized effective micropore and macropore diffusivities are comparable with experimental measurements achieved by other researchers.

  8. Nonlinear Data Transformation with Diffusion Map

    E-Print Network [OSTI]

    ) Others: Laplacian eigenmaps, Hessian eigenmaps, LTSA We apply the diffusion map (Coifman & Lafon 2006

  9. Prediction of Room Air Diffusion for Reduced Diffuser Flow Rates

    E-Print Network [OSTI]

    Gangisetti, Kavita

    2011-02-22T23:59:59.000Z

    ?, IEA Annex 20 project. The simulated results, in terms of maximum velocity, distribution of velocity and temperature in the room are validated against the experimental data. 3.1.1 Study the effect of various parameters on the CFD simulation. A study... and the walls of the room. The window is assumed to have a surface temperature of 30 0C.The diffuser used is a ?HESCO? type diffuser, which was used in the International Energy Agency (IEA) Annex 20 project (1993): ?Room air and contaminant flow, evaluation...

  10. Commercial Building Partnerships Replication and Diffusion

    SciTech Connect (OSTI)

    Antonopoulos, Chrissi A.; Dillon, Heather E.; Baechler, Michael C.

    2013-09-16T23:59:59.000Z

    This study presents findings from survey and interview data investigating replication efforts of Commercial Building Partnership (CBP) partners that worked directly with the Pacific Northwest National Laboratory (PNNL). PNNL partnered directly with 12 organizations on new and retrofit construction projects, which represented approximately 28 percent of the entire U.S. Department of Energy (DOE) CBP program. Through a feedback survey mechanism, along with personal interviews, PNNL gathered quantitative and qualitative data relating to replication efforts by each organization. These data were analyzed to provide insight into two primary research areas: 1) CBP partners’ replication efforts of technologies and approaches used in the CBP project to the rest of the organization’s building portfolio (including replication verification), and, 2) the market potential for technology diffusion into the total U.S. commercial building stock, as a direct result of the CBP program. The first area of this research focused specifically on replication efforts underway or planned by each CBP program participant. Factors that impact replication include motivation, organizational structure and objectives firms have for implementation of energy efficient technologies. Comparing these factors between different CBP partners revealed patterns in motivation for constructing energy efficient buildings, along with better insight into market trends for green building practices. The second area of this research develops a diffusion of innovations model to analyze potential broad market impacts of the CBP program on the commercial building industry in the United States.

  11. Support Operators Method for the Diffusion Equation in Multiple Materials

    SciTech Connect (OSTI)

    Winters, Andrew R. [Los Alamos National Laboratory; Shashkov, Mikhail J. [Los Alamos National Laboratory

    2012-08-14T23:59:59.000Z

    A second-order finite difference scheme for the solution of the diffusion equation on non-uniform meshes is implemented. The method allows the heat conductivity to be discontinuous. The algorithm is formulated on a one dimensional mesh and is derived using the support operators method. A key component of the derivation is that the discrete analog of the flux operator is constructed to be the negative adjoint of the discrete divergence, in an inner product that is a discrete analog of the continuum inner product. The resultant discrete operators in the fully discretized diffusion equation are symmetric and positive definite. The algorithm is generalized to operate on meshes with cells which have mixed material properties. A mechanism to recover intermediate temperature values in mixed cells using a limited linear reconstruction is introduced. The implementation of the algorithm is verified and the linear reconstruction mechanism is compared to previous results for obtaining new material temperatures.

  12. Beta Diffusion Trees Creighton Heaukulani

    E-Print Network [OSTI]

    Edinburgh, University of

    Beta Diffusion Trees Creighton Heaukulani CKH28@CAM.AC.UK David A. Knowles DAVIDKNOWLES Stanford University, Department of Computer Science, Stanford, CA, USA Abstract We define the beta structures over clusters of the particles. With the beta diffu- sion tree, however, multiple copies

  13. Phase Diffusion in Graphene-Based Josephson Junctions I. V. Borzenets, U. C. Coskun, S. J. Jones, and G. Finkelstein

    E-Print Network [OSTI]

    Finkelstein, Gleb

    Phase Diffusion in Graphene-Based Josephson Junctions I. V. Borzenets, U. C. Coskun, S. J. Jones July 2011; published 21 September 2011) We report on graphene-based Josephson junctions with contacts. We attribute this resistance to the phase diffusion mechanism, which has not been yet identified

  14. Diffusion in a potential landscape with stochastic resetting

    E-Print Network [OSTI]

    Arnab Pal

    2014-08-09T23:59:59.000Z

    The steady state of a Brownian particle diffusing in an arbitrary potential under the stochastic resetting mechanism has been studied. We show that there are different classes of nonequilibrium steady states depending on the nature of the potential. In the stable potential landscape, the system attains a well defined steady state however existence of the steady state for the unstable landscape is constrained. We have also investigated the transient properties of the propagator towards the steady state under the stochastic resetting mechanism. Finally, we have done numerical simulations to verify our analytical results.

  15. Configurational diffusion of asphaltenes in fresh and aged catalyst extrudates. Final technical report, September 20, 1991--September 30, 1996

    SciTech Connect (OSTI)

    Guin, J.A.

    1998-12-31T23:59:59.000Z

    The overall objective of this project was to investigate the diffusion of coal and petroleum asphaltenes in the pores of a supported catalyst. Experimental measurements together with mathematical modeling was conducted to determine how the diffusion rate of asphaltenes, as well as some model compounds, depended on molecule sizes and shapes. The process of diffusion in the pores of a porous medium may occur by several mechanisms. Hindered diffusion occurs when the sizes of the diffusion molecules are comparable to those of the porous pores through which they are diffusing. Hindered diffusion phenomena have been widely observed in catalytic hydrotreatment of asphaltenes, heavy oils, coal derived liquids, etc. Pore diffusion limitations can be greater in spent catalysts due to the deposition of coke and metals in the pores. In this work, a general mathematical model was developed for the hindered diffusion-adsorption of solute in a solvent onto porous materials, e. g. catalysts, from a surrounding bath. This diffusion model incorporated the nonuniformities of pore structures in the porous media. A numerical method called the Method of Lines was used to solve the nonlinear partial differential equations resulting from the mathematical model. The accuracy of the numerical solution was verified by both a mass balance in the diffusion system and satisfactory agreement with known solutions in several special cases.

  16. Sandia National Laboratories: Diffusion Bonding Characterization

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

    bond surface is poor or only the region near this corner Diffusion 7-8-9 Diffusion Welding and Brazing, Welding Handbook, 7th ed., American Welding Society, 1980, p 311-335...

  17. MICROFLUIDIC CONTROL OF STEM CELL DIFFUSIBLE SIGNALING

    E-Print Network [OSTI]

    Voldman, Joel

    MICROFLUIDIC CONTROL OF STEM CELL DIFFUSIBLE SIGNALING Katarina Blagovi, Lily Y. Kim, Alison M cell differentiation. KEYWORDS: Embryonic stem cells, microfluidic perfusion, diffusible signaling; they secrete molecules to which they respond. Microfluidics offers a potential solution to this challenge

  18. OXYGEN DIFFUSION IN UO2-x

    E-Print Network [OSTI]

    Kim, K.C.

    2013-01-01T23:59:59.000Z

    ~ K.C. K:i.m, "Oxygen Diffusion in Hypostoichiometricsystem for enriching uo 2 in oxygen-18 or for stoichiometry+nal of Nuclear Materials OXYGEN DIFFUSION IN U0 2 _:x K.C.

  19. Synergistic diffuser/heat-exchanger design

    E-Print Network [OSTI]

    Lazzara, David S. (David Sergio), 1980-

    2004-01-01T23:59:59.000Z

    The theoretical and numerical evaluation of synergistic diffusing heat-exchanger design is presented. Motivation for this development is based on current diffuser and heat-exchange technologies in cogeneration plants, which ...

  20. Hierarchical 3D diffusion wavelet shape priors

    E-Print Network [OSTI]

    Langs, Georg

    In this paper, we propose a novel representation of prior knowledge for image segmentation, using diffusion wavelets that can reflect arbitrary continuous interdependencies in shape data. The application of diffusion ...

  1. Analysis and calibration of social factors in a consumer acceptance and adoption model for diffusion of diesel vehicle in Europe

    E-Print Network [OSTI]

    Zhang, Qi, S.M. Massachusetts Institute of Technology

    2008-01-01T23:59:59.000Z

    While large scale diffusion of alternative fuel vehicles (AFVs) is widely anticipated, the mechanisms that determine their success or failure are ill understood. Analysis of an AFV transition model developed at MIT has ...

  2. Heat Hyperbolic Diffusion in Planck Gas

    E-Print Network [OSTI]

    Miroslaw Kozlowski; Janina Marciak-Kozlowska

    2006-07-06T23:59:59.000Z

    In this paper we investigate the diffusion of the thermal pulse in Planck Gas. We show that the Fourier diffusion equation gives the speed of diffusion, v > c and breaks the causality of the thermal processes in Planck gas .For hyperbolic heat transport v

  3. antigen uptake mechanism: Topics by E-print Network

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

    hepatotoxicity is considered to be the cause of the diffuse liver uptake of 99m Tc-MDP. The mechanism of extraskeletal uptake of bone-seeking radiopharmaceuticals in...

  4. Service Promotion -Diffusion Raphale LOMBARD

    E-Print Network [OSTI]

    Pellier, Damien

    Service Promotion - Diffusion Raphaële LOMBARD Editions L'Harmattan - 5 Rue de l'Ecole Polytechnique ­ 75005 Paris Tél 01.40.46.79.23 ­ mail : raphaele.lombard@harmattan.fr La mondialisation avance à complémentaires BON DE COMMANDE A retourner à L'HARMATTAN, 7 rue de l'�cole Polytechnique 75005 Paris Veuillez me

  5. Evaluation of Catalysts from Different Origin for Vapor Phase Upgrading in Biomass Pyrolysis

    SciTech Connect (OSTI)

    Zhang, X.; Mukarakate, C.; Zheng, Z.; Nimlos, M.

    2012-01-01T23:59:59.000Z

    Liquid fuels and chemicals from biomass resources arouse much interests in research and development. Fast pyrolysis of biomass has the potential to effectively change solid biomass materials into liquid products. However, bio-oil from traditional pyrolysis processes is difficult to apply in industry, because of its complicated composition, high oxygen content, low stability, etc. Upgrading or refining of the bio-oil should be performed for industrial application of biomass pyrolysis. Often, the process would be done in a separate reactor downstream of the pyrolysis process. In this paper, a laboratory scale micro test facility was constructed, wherein the pyrolysis of pine and catalytic upgrading of the resulting vapors were closely coupled in one reactor. The composition of vapor effluent was monitored with a molecular beam mass spectrometer (MBMS) for the online evaluation of the catalyst performance. Catalysts from different origin were tested and compared for the effectiveness of pyrolysis vapor upgrading, namely commercial zeolites, Ni based steam reforming catalyst, CaO, MgO, and several laboratory-made catalysts. The reaction temperature for catalytic upgrading varied between 400 and 600 centigrade, and the gaseous residence time ranged from 0.1 second to above 2 second, to simulate the conditions in industrial application. It is revealed that some catalysts are active in transform most of primary biomass pyrolysis vapors into hydrocarbons, resulting in nonoxygenated products, which is beneficial for downstream utilization. Others are not as effective, results in minor improvement compared with blank test results.

  6. Controlled Vapor Phase Growth of Single Crystalline, Two-Dimensional GaSe

    E-Print Network [OSTI]

    Geohegan, David B.

    , and have the potential to enable next-generation electronic and optoelectronic devices. However, controlled-generation electronic and optoelectronic devices such as photodetectors and field-effect transistors. T wo-generation electronic and optoelectronic devices. Although most research has focused on 2D transition metal

  7. Liquid-phase and vapor-phase dehydration of organic/water solutions

    DOE Patents [OSTI]

    Huang, Yu (Palo Alto, CA); Ly, Jennifer (San Jose, CA); Aldajani, Tiem (San Jose, CA); Baker, Richard W. (Palo Alto, CA)

    2011-08-23T23:59:59.000Z

    Processes for dehydrating an organic/water solution by pervaporation or vapor separation using fluorinated membranes. The processes are particularly useful for treating mixtures containing light organic components, such as ethanol, isopropanol or acetic acid.

  8. A NOVEL VAPOR-PHASE PROCESS FOR DEEP DESULFURIZATION OF NAPHTHA/DIESEL

    SciTech Connect (OSTI)

    B.S. Turk; R.P. Gupta; S.K. Gangwal

    2003-06-30T23:59:59.000Z

    Tier 2 regulations issued by the U.S. Environmental Protection Agency (EPA) require a substantial reduction in the sulfur content of gasoline. Similar regulations have been enacted for the sulfur level in on-road diesel and recently off-road diesel. The removal of this sulfur with existing and installed technology faces technical and economic challenges. These challenges created the opportunity for new emerging technologies. Research Triangle Institute (RTI) with subcontract support from Kellogg Brown & Root, Inc., (KBR) used this opportunity to develop RTI's transport reactor naphtha desulfurization (TReND) process. Starting with a simple conceptual process design and some laboratory results that showed promise, RTI initiated an accelerated research program for sorbent development, process development, and marketing and commercialization. Sorbent development has resulted in the identification of an active and attrition resistant sorbent that has been prepared in commercial equipment in 100 lb batches. Process development has demonstrated both the sulfur removal performance and regeneration potential of this sorbent. Process development has scaled up testing from small laboratory to pilot plant transport reactor testing. Testing in the transport reactor pilot plant has demonstrated the attrition resistance, selective sulfur removal activity, and regeneration activity of this sorbent material. Marketing and commercialization activities have shown with the existing information that the process has significant capital and operating cost benefits over existing and other emerging technologies. The market assessment and analysis provided valuable feedback about the testing and performance requirements for the technical development program. This market analysis also provided a list of potential candidates for hosting a demonstration unit. Although the narrow window of opportunity generated by the new sulfur regulations and the conservative nature of the refining industry slowed progress of the demonstration unit, negotiations with potential partners are proceeding for commercialization of this process.

  9. Bundles of carbon nanotubes generated by vapor-phase growth Maohui Ge and Klaus Sattler

    E-Print Network [OSTI]

    Sattler, Klaus

    show that another hollow carbon structure is possible to form under such high density conditions. We report the observation of assemblies of carbon nano- tubes in the form of bundles. The bundles. It is located horizontally on the flat graphite substrate. It is separated from other deposited carbon nano

  10. Vapor-Phase Metalation by Atomic Layer Deposition in a Metal-Organic Framework

    E-Print Network [OSTI]

    encompass deposition onto micro- and nanopowders14 and coating of nanoparticle films15 as well as aerogel coating of porous materials that exhibit ultrahigh-aspect ratios.12,13 To date, some striking examples

  11. Carbon-Supported bimetallic Pd-Fe catalysts for vapor-phase

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation Proposed New Substation Sites Proposed RouteNanotube Templated

  12. Absolute integrated intensities of vapor-phase hydrogen peroxide (H202) in

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsruc Documentation RUCProductstwrmrAre the Effects ofAbout ScienceAbout Oak RidgeAboutthe

  13. Vapor phase ketonization of acetic acid on ceria based metal oxides

    SciTech Connect (OSTI)

    Liu, Changjun; Karim, Ayman M.; Lebarbier, Vanessa MC; Mei, Donghai; Wang, Yong

    2013-12-01T23:59:59.000Z

    The activities of CeO2, Mn2O3-CeO2 and ZrO2-CeO2 were measured for acetic acid ketonization under reaction conditions relevant to pyrolysis vapor upgrading. We show that the catalyst ranking changed depending on the reaction conditions. Mn2O3-CeO2 was the most active catalyst at 350 oC, while ZrO2 - CeO2 was the most active catalyst at 450 oC. Under high CO2 and steam concentration in the reactants, Mn2O3-CeO2 was the most active catalyst at 350 and 450 °C. The binding energies of steam and CO2 with the active phase were calculated to provide the insight into the tolerance of Mn2O3-CeO2 to steam and CO2.

  14. NOVEL PROCESS FOR REMOVAL AND RECOVERY OF VAPOR-PHASE MERCURY

    SciTech Connect (OSTI)

    Craig S. Turchi

    2000-09-29T23:59:59.000Z

    The goal of this project is to investigate the use of a regenerable sorbent for removing and recovering mercury from the flue gas of coal-fired power plants. The process is based on the sorption of mercury by noble metals and the thermal regeneration of the sorbent, recovering the desorbed mercury in a small volume for recycling or disposal. The project was carried out in two phases, covering five years. Phase I ran from September 1995 through September 1997 and involved development and testing of sorbent materials and field tests at a pilot coal-combustor. Phase II began in January 1998 and ended September 2000. Phase II culminated with pilot-scale testing at a coal-fired power plant. The use of regenerable sorbents holds the promise of capturing mercury in a small volume, suitable for either stable disposal or recycling. Unlike single-use injected sorbents such as activated carbon, there is no impact on the quality of the fly ash. During Phase II, tests were run with a 20-acfm pilot unit on coal-combustion flue gas at a 100 lb/hr pilot combustor and a utility boiler for four months and six months respectively. These studies, and subsequent laboratory comparisons, indicated that the sorbent capacity and life were detrimentally affected by the flue gas constituents. Sorbent capacity dropped by a factor of 20 to 35 during operations in flue gas versus air. Thus, a sorbent designed to last 24 hours between recycling lasted less than one hour. The effect resulted from an interaction between SO{sub 2} and either NO{sub 2} or HCl. When SO{sub 2} was combined with either of these two gases, total breakthrough was seen within one hour in flue gas. This behavior is similar to that reported by others with carbon adsorbents (Miller et al., 1998).

  15. Effects of multi-component diffusion and heat release on laminar diffusion flame liftoff

    SciTech Connect (OSTI)

    Li, Zhiliang; Chen, Ruey-Hung [Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL 32816-2450 (United States); Phuoc, Tran X. [National Energy Technology Laboratory, Department of Energy, P.O. Box 10940, MS 84-340, Pittsburgh, PA 15261 (United States)

    2010-08-15T23:59:59.000Z

    Numerical simulations were conducted of the liftoff and stabilization phenomena of laminar jet diffusion flames of inert-diluted C{sub 3}H{sub 8} and CH{sub 4} fuels. Both non-reacting and reacting jets were investigated, including multi-component diffusivities and heat release effects (buoyancy and gas expansion). The role of Schmidt number for non-reacting jets was investigated, with no conclusive Schmidt number criterion for liftoff previously arrived at in similarity solutions. The cold-flow simulation for He-diluted CH{sub 4} fuel does not predict flame liftoff; however, adding heat release reaction lead to the prediction of liftoff, which is consistent with experimental observations. Including reaction was also found to improve liftoff height prediction for C{sub 3}H{sub 8} flames, with the flame base location differing from that in the similarity solution - the intersection of the stoichiometric and iso-velocity (equal to 1-D flame speed) is not necessary for flame stabilization (and thus liftoff). Possible mechanisms other than that proposed for similarity solution may better help to explain the stabilization and liftoff phenomena. (author)

  16. On the thermodynamics of volume/mass diffusion in fluids

    E-Print Network [OSTI]

    S. Kokou Dadzie; Jason M. Reese

    2012-04-07T23:59:59.000Z

    In Physica A vol 387(24) (2008) pp6079-6094 [1], a kinetic equation for gas flows was proposed that leads to a set of four macroscopic conservation equations, rather than the traditional set of three equations. The additional equation arises due to local spatial random molecular behavior, which has been described as a volume or mass diffusion process. In this present paper, we describe a procedure to construct a Gibbs-type equation and a second-law associated with these kinetic and continuum models. We also point out the close link between the kinetic equation in [1] and that proposed previously by Klimontovich, and we discuss some of their compatibilities with classical mechanical principles. Finally, a dimensional analysis highlights the nature of volume/mass diffusion: it is a non-conventional diffusive process, with some similarities to the `ghost effect', which cannot be obtained from a fluid mechanical derivation that neglects non-local-equilibrium structures, as the conventional Navier-Stokes-Fourier model does.

  17. Group classification of systems of non-linear reaction-diffusion equations with general diffusion matrix. II. Generalized Turing systems

    E-Print Network [OSTI]

    A. G. Nikitin

    2007-07-20T23:59:59.000Z

    Group classification of systems of two coupled nonlinear reaction-diffusion equation with a diagonal diffusion matrix is carried out. Symmetries of diffusion systems with singular diffusion matrix and additional first order derivative terms are described.

  18. Synchronous parallel kinetic Monte Carlo Diffusion in Heterogeneous Systems

    SciTech Connect (OSTI)

    Martinez Saez, Enrique [Los Alamos National Laboratory; Hetherly, Jeffery [Los Alamos National Laboratory; Caro, Jose A [Los Alamos National Laboratory

    2010-12-06T23:59:59.000Z

    A new hybrid Molecular Dynamics-kinetic Monte Carlo algorithm has been developed in order to study the basic mechanisms taking place in diffusion in concentrated alloys under the action of chemical and stress fields. Parallel implementation of the k-MC part based on a recently developed synchronous algorithm [1. Compo Phys. 227 (2008) 3804-3823] resorting on the introduction of a set of null events aiming at synchronizing the time for the different subdomains, added to the parallel efficiency of MD, provides the computer power required to evaluate jump rates 'on the flight', incorporating in this way the actual driving force emerging from chemical potential gradients, and the actual environment-dependent jump rates. The time gain has been analyzed and the parallel performance reported. The algorithm is tested on simple diffusion problems to verify its accuracy.

  19. AMBIPOLAR DIFFUSION HEATING IN TURBULENT SYSTEMS

    SciTech Connect (OSTI)

    Li, Pak Shing [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Myers, Andrew [Physics Department, University of California, Berkeley, CA 94720 (United States); McKee, Christopher F., E-mail: psli@astron.berkeley.edu, E-mail: atmyers@berkeley.edu, E-mail: cmckee@berkeley.edu [Physics Department and Astronomy Department, University of California, Berkeley, CA 94720 (United States)

    2012-11-20T23:59:59.000Z

    The temperature of the gas in molecular clouds is a key determinant of the characteristic mass of star formation. Ambipolar diffusion (AD) is considered one of the most important heating mechanisms in weakly ionized molecular clouds. In this work, we study the AD heating rate using two-fluid turbulence simulations and compare it with the overall heating rate due to turbulent dissipation. We find that for observed molecular clouds, which typically have Alfven Mach numbers of {approx}1 and AD Reynolds numbers of {approx}20, about 70% of the total turbulent dissipation is in the form of AD heating. AD has an important effect on the length scale where energy is dissipated: when AD heating is strong, most of the energy in the cascade is removed by ion-neutral drift, with a comparatively small amount of energy making it down to small scales. We derive a relation for the AD heating rate that describes the results of our simulations to within a factor of two. Turbulent dissipation, including AD heating, is generally less important than cosmic-ray heating in molecular clouds, although there is substantial scatter in both.

  20. Diffusion processes in general relativistic radiating spheres

    SciTech Connect (OSTI)

    Barreto, W.; Herrera, L.; Santos, N.O. (Oriente Universidad, Cumana (Venezuela); Universidad Central de Venezuela, Caracas; Observatorio Nacional do Brasil, Rio de Janeiro (Brazil))

    1989-09-01T23:59:59.000Z

    The influence of diffusion processes on the dynamics of general relativistic radiating spheres is systematically studied by means of two examples. Differences between the streaming-out limit and the diffusion limit are exhibited, for both models, through the evolution curves of dynamical variables. In particular it is shown the Bondi mass decreases, for both models, in the diffusion limit as compared with its value at the streaming-out regime. 15 refs.

  1. Characterizing unsaturated diffusion in porous tuff gravel

    SciTech Connect (OSTI)

    Hu, Qinhong; Kneafsey, Timothy J.; Roberts, Jeffery J.; Tomutsa, Liviu; Wang, Joseph, S.Y.

    2003-11-12T23:59:59.000Z

    Evaluation of solute diffusion in unsaturated porous gravel is very important for investigations of contaminant transport and remediation, risk assessment, and waste disposal (for example, the potential high-level nuclear waste repository at Yucca Mountain, Nevada). For a porous aggregate medium such as granular tuff, the total water content is comprised of surface water and interior water. The surface water component (water film around grains and pendular water between the grain contacts) could serve as a predominant diffusion pathway. To investigate the extent to which surface water films and contact points affect solute diffusion in unsaturated gravel, we examined the configuration of water using x-ray computed tomography in partially saturated gravel, and made quantitative measurements of diffusion at multiple water contents using two different techniques. In the first, diffusion coefficients of potassium chloride in 2-4 mm granular tuff at multiple water contents were calculated from electrical conductivity measurements using the Nernst-Einstein equation. In the second, we used laser ablation with inductively coupled plasma-mass spectrometry to perform micro-scale mapping, allowing the measurement of diffusion coefficients for a mixture of chemical tracers for tuff cubes and tetrahedrons having two contact geometries (cube-cube and cube-tetrahedron). The x-ray computed tomography images show limited contact between grains, and this could hinder the pathways for diffusive transport. Experimental results show the critical role of surface water in controlling transport pathways and hence the magnitude of diffusion. Even with a bulk volumetric water content of 1.5%, the measured solute diffusion coefficient is as low as 1.5 x 10{sup -14} m{sup 2}/s for tuff gravel. Currently used diffusion models relating diffusion coefficients to total volumetric water content inadequately describe unsaturated diffusion behavior in porous gravel at very low water contents.

  2. Boron-enhanced diffusion of boron from ultralow-energy boron implantation

    SciTech Connect (OSTI)

    Agarwal, A.; Eaglesham, D.J.; Gossmann, H.J.; Pelaz, L.; Herner, S.B.; Jacobson, D.C. [Lucent Technologies, Murray Hill, NJ (United States). Bell Labs.; Haynes, T.E. [Oak Ridge National Lab., TN (United States). Solid State Div.; Erokhin, Y.E. [Eaton Corp., Beverly, MA (United States)

    1998-05-03T23:59:59.000Z

    The authors have investigated the diffusion enhancement mechanism of BED (boron enhanced diffusion), wherein the boron diffusivity is enhanced three to four times over the equilibrium diffusivity at 1,050 C in the proximity of a silicon layer containing a high boron concentration. It is shown that BED is associated with the formation of a fine-grain polycrystalline silicon boride phase within an initially amorphous Si layer having a high B concentration. For 0.5 keV B{sup +}, the threshold implantation dose which leads to BED lies between 3 {times} 10{sup 14} and of 1 {times} 10{sup 15}/cm{sup {minus}2}. Formation of the shallowest possible junctions by 0.5 keV B{sup +} requires that the implant dose be kept lower than this threshold.

  3. Self-Similar Modes of Coherent Diffusion

    E-Print Network [OSTI]

    O. Firstenberg; P. London; D. Yankelev; R. Pugatch; M. Shuker; N. Davidson

    2010-08-16T23:59:59.000Z

    Self-similar solutions of the coherent diffusion equation are derived and measured. The set of real similarity solutions is generalized by the introduction of a nonuniform phase surface, based on the elegant Gaussian modes of optical diffraction. In an experiment of light storage in a gas of diffusing atoms, a complex initial condition is imprinted, and its diffusion dynamics is monitored. The self-similarity of both the amplitude and the phase pattern is demonstrated, and an algebraic decay associated with the mode order is measured. Notably, as opposed to a regular diffusion spreading, a self-similar contraction of a special subset of the solutions is predicted and observed.

  4. Independent Activity Report, Portsmouth Gaseous Diffusion Plant...

    Broader source: Energy.gov (indexed) [DOE]

    2011 August 2011 Orientation Visit to the Portsmouth Gaseous Diffusion Plant HIAR-PORTS-2011-08-03 This Independent Activity Report documents an operational awareness...

  5. Mechanical memory

    DOE Patents [OSTI]

    Gilkey, Jeffrey C. (Albuquerque, NM); Duesterhaus, Michelle A. (Albuquerque, NM); Peter, Frank J. (Albuquerque, NM); Renn, Rosemarie A. (Albuquerque, NM); Baker, Michael S. (Albuquerque, NM)

    2006-05-16T23:59:59.000Z

    A first-in-first-out (FIFO) microelectromechanical memory apparatus (also termed a mechanical memory) is disclosed. The mechanical memory utilizes a plurality of memory cells, with each memory cell having a beam which can be bowed in either of two directions of curvature to indicate two different logic states for that memory cell. The memory cells can be arranged around a wheel which operates as a clocking actuator to serially shift data from one memory cell to the next. The mechanical memory can be formed using conventional surface micromachining, and can be formed as either a nonvolatile memory or as a volatile memory.

  6. Mechanical memory

    DOE Patents [OSTI]

    Gilkey, Jeffrey C. (Albuquerque, NM); Duesterhaus, Michelle A. (Albuquerque, NM); Peter, Frank J. (Albuquerque, NM); Renn, Rosemarie A. (Alburquerque, NM); Baker, Michael S. (Albuquerque, NM)

    2006-08-15T23:59:59.000Z

    A first-in-first-out (FIFO) microelectromechanical memory apparatus (also termed a mechanical memory) is disclosed. The mechanical memory utilizes a plurality of memory cells, with each memory cell having a beam which can be bowed in either of two directions of curvature to indicate two different logic states for that memory cell. The memory cells can be arranged around a wheel which operates as a clocking actuator to serially shift data from one memory cell to the next. The mechanical memory can be formed using conventional surface micromachining, and can be formed as either a nonvolatile memory or as a volatile memory.

  7. Torsion Testing of Diffusion Bonded LIGA Formed Nickel

    SciTech Connect (OSTI)

    Buchheit, T.E.; Christenson, T.R.; Schmale, D.T.

    1999-01-27T23:59:59.000Z

    A test technique has been devised which is suitable for the testing of the bond strength of batch diffusion bonded LIGA or DXRL defined structures. The method uses a torsion tester constructed with the aid of LIGA fabrication and distributed torsion specimens which also make use of the high aspect ratio nature of DXRL based processing. Measurements reveal achieved bond strengths of 130MPa between electroplated nickel with a bond temperature of 450 C at 7 ksi pressure which is a sufficiently low temperature to avoid mechanical strength degradation.

  8. Thermal Particle Injection in Nonlinear Diffusive Shock Acceleration

    E-Print Network [OSTI]

    Donald C. Ellison; Pasquale Blasi; Stefano Gabici

    2005-07-05T23:59:59.000Z

    Particle acceleration in collisionless astrophysical shocks, i.e., diffusive shock acceleration (DSA), is the most likely mechanism for producing cosmic rays, at least below 10^{15} eV. Despite the success of this theory, several key elements, including the injection of thermal particles, remains poorly understood. We investigate injection in strongly nonlinear shocks by comparing a semi-analytic model of DSA with a Monte Carlo model. These two models treat injection quite differently and we show, for a particular set of parameters, how these differences influence the overall acceleration efficiency and the shape of the broad-band distribution function.

  9. Progress Report for Diffusion Welding of the NGNP Process Application Heat Exchangers

    SciTech Connect (OSTI)

    R.E. Mizia; D.E. Clark; M.V. Glazoff; T.E. Lister; T.L. Trowbridge

    2011-12-01T23:59:59.000Z

    The U.S. Department of Energy selected the high temperature gas-cooled reactor as the basis for the Next Generation Nuclear Plant (NGNP). The NGNP will demonstrate the use of nuclear power for electricity, hydrogen production, and process heat applications. The NGNP Project is currently investigating the use of metallic, diffusion welded, compact heat exchangers to transfer heat from the primary (reactor side) heat transport system to the secondary heat transport system. An intermediate heat exchanger will transfer this heat to downstream applications such as hydrogen production, process heat, and electricity generation. The channeled plates that make up the heat transfer surfaces of the intermediate heat exchanger will have to be assembled into an array by diffusion welding. This report describes the preliminary results of a scoping study that evaluated the diffusion welding process parameters and the resultant mechanical properties of diffusion welded joints using Alloy 800H. The long-term goal of the program is to progress towards demonstration of small heat exchanger unit cells fabricated with diffusion welds. Demonstration through mechanical testing of the unit cells will support American Society of Mechanical Engineers rules and standards development, reduce technical risk, and provide proof of concept for heat exchanger fabrication methods needed to deploy heat exchangers in several potential NGNP configurations.1 Researchers also evaluated the usefulness of modern thermodynamic and diffusion computational tools (Thermo-Calc and Dictra) in optimizing the parameters for diffusion welding of Alloy 800H. The modeling efforts suggested a temperature of 1150 C for 1 hour with an applied pressure of 5 MPa using 15 {micro}m nickel foil as joint filler to reduce chromium oxidation on the welded surfaces. Good agreement between modeled and experimentally determined concentration gradients was achieved

  10. Modelling international wind energy diffusion: Are the patterns of induced diffusion `S'

    E-Print Network [OSTI]

    Feigon, Brooke

    Modelling international wind energy diffusion: Are the patterns of induced diffusion `S' shaped datasets, the paper explores the patterns of international wind energy diffusion in OECD countries. The model employed in the paper predicted that wind energy, as a complex and expensive innovation, would

  11. Boron diffusion in nanocrystalline 3C-SiC

    SciTech Connect (OSTI)

    Schnabel, Manuel, E-mail: manuel.schnabel@ise.fraunhofer.de [Fraunhofer ISE, Heidenhofstr. 2, 79110 Freiburg (Germany); Department of Materials, University of Oxford, Parks Rd, Oxford OX1 3PH (United Kingdom); Weiss, Charlotte; Rachow, Thomas; Löper, Philipp; Janz, Stefan [Fraunhofer ISE, Heidenhofstr. 2, 79110 Freiburg (Germany); Canino, Mariaconcetta; Summonte, Caterina [CNR-IMM, Via Piero Gobetti 101, 40129 Bologna (Italy); Mirabella, Salvo [CNR-IMM MATIS, Via S. Sofia 64, 95123 Catania (Italy); Wilshaw, Peter R. [Department of Materials, University of Oxford, Parks Rd, Oxford OX1 3PH (United Kingdom)

    2014-05-26T23:59:59.000Z

    The diffusion of boron in nanocrystalline silicon carbide (nc-SiC) films with a grain size of 4–7 nm is studied using a poly-Si boron source. Diffusion is found to be much faster than in monocrystalline SiC as it takes place within the grain boundary (GB) network. Drive-in temperatures of 900–1000°C are suitable for creating shallow boron profiles up to 100?nm deep, while 1100°C is sufficient to flood the 200?nm thick films with boron. From the resulting plateau at 1100?°C a boron segregation coefficient of 28 between nc-SiC and the Si substrate, as well as a GB boron solubility limit of 0.2?nm{sup ?2} is determined. GB diffusion in the bulk of the films is Fickian and thermally activated with D{sub GB}(T)=(3.1?5.6)×10{sup 7}exp(?5.03±0.16??eV/k{sub B}T) cm{sup 2}s{sup ?1}. The activation energy is interpreted in terms of a trapping mechanism at dangling bonds. Higher boron concentrations are present at the nc-SiC surface and are attributed to immobilized boron.

  12. Finite-difference schemes for anisotropic diffusion

    SciTech Connect (OSTI)

    Es, Bram van, E-mail: es@cwi.nl [Centrum Wiskunde and Informatica, P.O. Box 94079, 1090GB Amsterdam (Netherlands); FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM (Netherlands); Koren, Barry [Eindhoven University of Technology (Netherlands); Blank, Hugo J. de [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM (Netherlands)

    2014-09-01T23:59:59.000Z

    In fusion plasmas diffusion tensors are extremely anisotropic due to the high temperature and large magnetic field strength. This causes diffusion, heat conduction, and viscous momentum loss, to effectively be aligned with the magnetic field lines. This alignment leads to different values for the respective diffusive coefficients in the magnetic field direction and in the perpendicular direction, to the extent that heat diffusion coefficients can be up to 10{sup 12} times larger in the parallel direction than in the perpendicular direction. This anisotropy puts stringent requirements on the numerical methods used to approximate the MHD-equations since any misalignment of the grid may cause the perpendicular diffusion to be polluted by the numerical error in approximating the parallel diffusion. Currently the common approach is to apply magnetic field-aligned coordinates, an approach that automatically takes care of the directionality of the diffusive coefficients. This approach runs into problems at x-points and at points where there is magnetic re-connection, since this causes local non-alignment. It is therefore useful to consider numerical schemes that are tolerant to the misalignment of the grid with the magnetic field lines, both to improve existing methods and to help open the possibility of applying regular non-aligned grids. To investigate this, in this paper several discretization schemes are developed and applied to the anisotropic heat diffusion equation on a non-aligned grid.

  13. CONVERTIBLE BONDS IN A DEFAULTABLE DIFFUSION MODEL

    E-Print Network [OSTI]

    Jeanblanc, Monique

    CONVERTIBLE BONDS IN A DEFAULTABLE DIFFUSION MODEL Tomasz R. Bielecki Department of Applied Research Grant PS12918. #12;2 Convertible Bonds in a Defaultable Diffusion Model 1 Introduction In [4), such as Convertible Bonds (CB), and we provided a rigorous decomposition of a CB into a bond component and a (game

  14. ON DIFFUSION IN HETEROGENEOUS MEDIA YOUXUE ZHANG*,

    E-Print Network [OSTI]

    Liu, Liping

    , heterogeneous media, multi-mineral rocks, multi-phase media, composite materials, kinetics, porous rocks to bulk diffusion, and porous materials (such as plants, soil, rock with partial melt or fluid, sediment of air and moisture in soils, drying of paint, wood, and concrete, diffusion of gases in rubber, movement

  15. ANISOTROPIC DIFFUSION USING POWER WATERSHEDS Camille Couprie

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    optimal methods such as graph cuts have received a lot of attention. However not all problems in com are able to optimize this energy quickly and effectively. This study paves the way for using the power and the diffusion time. Practical usage of anisotropic diffusion requires a choice between long compu- tation times

  16. Study of lithium diffusion in RF sputtered Nickel/Vanadium mixed oxides thin films

    E-Print Network [OSTI]

    Artuso, Florinda

    Study of lithium diffusion in RF sputtered NickelÁ/Vanadium mixed oxides thin films F. Artuso a lithium insertion inside RF sputtered Ni/V mixed oxides thin films have been investigated employing, showed three steps clearly involved in the intercalation mechanism of lithium in the oxide films: (i

  17. Inverse diffusion from knowledge of power densities

    E-Print Network [OSTI]

    Bal, Guillaume; Monard, Francois; Triki, Faouzi

    2011-01-01T23:59:59.000Z

    This paper concerns the reconstruction of a diffusion coefficient in an elliptic equation from knowledge of several power densities. The power density is the product of the diffusion coefficient with the square of the modulus of the gradient of the elliptic solution. The derivation of such internal functionals comes from perturbing the medium of interest by acoustic (plane) waves, which results in small changes in the diffusion coefficient. After appropriate asymptotic expansions and (Fourier) transformation, this allow us to construct the power density of the equation point-wise inside the domain. Such a setting finds applications in ultrasound modulated electrical impedance tomography and ultrasound modulated optical tomography. We show that the diffusion coefficient can be uniquely and stably reconstructed from knowledge of a sufficient large number of power densities. Explicit expressions for the reconstruction of the diffusion coefficient are also provided. Such results hold for a large class of boundary...

  18. Computational mechanics

    SciTech Connect (OSTI)

    Goudreau, G.L.

    1993-03-01T23:59:59.000Z

    The Computational Mechanics thrust area sponsors research into the underlying solid, structural and fluid mechanics and heat transfer necessary for the development of state-of-the-art general purpose computational software. The scale of computational capability spans office workstations, departmental computer servers, and Cray-class supercomputers. The DYNA, NIKE, and TOPAZ codes have achieved world fame through our broad collaborators program, in addition to their strong support of on-going Lawrence Livermore National Laboratory (LLNL) programs. Several technology transfer initiatives have been based on these established codes, teaming LLNL analysts and researchers with counterparts in industry, extending code capability to specific industrial interests of casting, metalforming, and automobile crash dynamics. The next-generation solid/structural mechanics code, ParaDyn, is targeted toward massively parallel computers, which will extend performance from gigaflop to teraflop power. Our work for FY-92 is described in the following eight articles: (1) Solution Strategies: New Approaches for Strongly Nonlinear Quasistatic Problems Using DYNA3D; (2) Enhanced Enforcement of Mechanical Contact: The Method of Augmented Lagrangians; (3) ParaDyn: New Generation Solid/Structural Mechanics Codes for Massively Parallel Processors; (4) Composite Damage Modeling; (5) HYDRA: A Parallel/Vector Flow Solver for Three-Dimensional, Transient, Incompressible Viscous How; (6) Development and Testing of the TRIM3D Radiation Heat Transfer Code; (7) A Methodology for Calculating the Seismic Response of Critical Structures; and (8) Reinforced Concrete Damage Modeling.

  19. An observable for vacancy characterization and diffusion in crystals

    E-Print Network [OSTI]

    Pierre-Antoine Geslin; Giovanni Ciccotti; Eric Vanden-Eijnden; Simone Meloni

    2012-11-20T23:59:59.000Z

    To locate the position and characterize the dynamics of a vacancy in a crystal, we propose to represent it by the ground state density of a quantum probe quasi-particle for the Hamiltonian associated to the potential energy field generated by the atoms in the sample. In this description, the h^2/2mu coefficient of the kinetic energy term is a tunable parameter controlling the density localization in the regions of relevant minima of the potential energy field. Based on this description, we derive a set of collective variables that we use in rare event simulations to identify some of the vacancy diffusion paths in a 2D crystal. Our simulations reveal, in addition to the simple and expected nearest neighbor hopping path, a collective migration mechanism of the vacancy. This mechanism involves several lattice sites and produces a long range migration of the vacancy. Finally, we also observed a vacancy induced crystal reorientation process.

  20. Optoelectronic switches based on diffusive conduction Hilmi Volkan Demira

    E-Print Network [OSTI]

    Miller, David A. B.

    Optoelectronic switches based on diffusive conduction Hilmi Volkan Demira and Fatih Hakan Koklu the process of diffusive conduction that we use in our optoelectronic switches to achieve rapid optical. We demonstrate the feasibility of using such diffusive conductive optoelectronic switches

  1. Review of enhanced vapor diffusion in porous media

    SciTech Connect (OSTI)

    Webb, S.W.; Ho, C.K.

    1998-08-01T23:59:59.000Z

    Vapor diffusion in porous media in the presence of its own liquid has often been treated similar to gas diffusion. The gas diffusion rate in porous media is much lower than in free space due to the presence of the porous medium and any liquid present. However, enhanced vapor diffusion has also been postulated such that the diffusion rate may approach free-space values. Existing data and models for enhanced vapor diffusion, including those in TOUGH2, are reviewed in this paper.

  2. HINDERED DIFFUSION OF COAL LIQUIDS

    SciTech Connect (OSTI)

    Theodore T. Tsotsis; Muhammad Sahimi; Ian A. Webster

    1996-01-01T23:59:59.000Z

    It was the purpose of the project described here to carry out careful and detailed investigations of petroleum and coal asphaltene transport through model porous systems under a broad range of temperature conditions. The experimental studies were to be coupled with detailed, in-depth statistical and molecular dynamics models intended to provide a fundamental understanding of the overall transport mechanisms and a more accurate concept of the asphaltene structure. The following discussion describes some of our accomplishments.

  3. Mixing it up - Measuring diffusion in supercooled liquid solutions...

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

    Mixing it up - Measuring diffusion in supercooled liquid solutions of methanol and ethanol at temperatures near the glass Mixing it up - Measuring diffusion in supercooled liquid...

  4. Non-Destructive Analysis Calibration Standards for Gaseous Diffusion...

    Broader source: Energy.gov (indexed) [DOE]

    Non-Destructive Analysis Calibration Standards for Gaseous Diffusion Plant (GDP) Decommissioning Non-Destructive Analysis Calibration Standards for Gaseous Diffusion Plant (GDP)...

  5. ar diffusion coefficient: Topics by E-print Network

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

    diffusion is examined. Kazuhiko Seki; Saurabh Mogre; Shigeyuki Komura 2014-02-05 4 Fractal diffusion coefficient from dynamical zeta functions Nonlinear Sciences (arXiv)...

  6. axial diffusion coefficient: Topics by E-print Network

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

    diffusion is examined. Kazuhiko Seki; Saurabh Mogre; Shigeyuki Komura 2014-02-05 5 Fractal diffusion coefficient from dynamical zeta functions Nonlinear Sciences (arXiv)...

  7. Oxygen Diffusion (OD) Dramatically Improves Wear-Resistance of...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Oxygen Diffusion (OD) Dramatically Improves Wear-Resistance of Titanium Oxygen Diffusion (OD) Dramatically Improves Wear-Resistance of Titanium 2007 Diesel Engine-Efficiency &...

  8. Hydrogen diffusion in Lead Zirconate Titanate and Barium Titanate...

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

    diffusion in Lead Zirconate Titanate and Barium Titanate. Hydrogen diffusion in Lead Zirconate Titanate and Barium Titanate. Abstract: Hydrogen is a potential clean-burning,...

  9. Agreement Mechanisms

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsruc Documentation RUCProductstwrmrAre theAdministratorCFM LEAPAgenda AgendaAgreement Mechanisms

  10. Diffusion of Innovations over Multiplex Social Networks

    E-Print Network [OSTI]

    Ramezanian, Rasoul; Magnani, Matteo; Montesi, Danilo

    2014-01-01T23:59:59.000Z

    The ways in which an innovation (e.g., new behaviour, idea, technology, product) diffuses among people can determine its success or failure. In this paper, we address the problem of diffusion of innovations over multiplex social networks where the neighbours of a person belong to one or multiple networks (or layers) such as friends, families, or colleagues. To this end, we generalise one of the basic game-theoretic diffusion models, called networked coordination game, for multiplex networks. We present analytical results for this extended model and validate them through a simulation study, finding among other properties a lower bound for the success of an innovation.While simple and leading to intuitively understandable results, to the best of our knowledge this is the first extension of a game-theoretic innovation diffusion model for multiplex networks and as such it provides a basic framework to study more sophisticated innovation dynamics.

  11. Diffusion of innovations in social networks

    E-Print Network [OSTI]

    Acemoglu, Daron

    While social networks do affect diffusion of innovations, the exact nature of these effects are far from clear, and, in many cases, there exist conflicting hypotheses among researchers. In this paper, we focus on the linear ...

  12. Princeton University Diffusion of Networking Technologies

    E-Print Network [OSTI]

    Goldberg, Sharon

    Electronic Commerce (EC'12) Valencia, Spain June 7, 2012 ISP #12;Seedset: A set of nodes that can kick off, photovoltaics, fax, computers, Internet, video games, ... Source: Rogers. "The Diffusion of Home Computers Among

  13. Diffuser Augmented Wind Turbine Analysis Code

    E-Print Network [OSTI]

    Carroll, Jonathan

    2014-05-31T23:59:59.000Z

    , it is necessary to develop innovative wind capturing devices that can produce energy in the locations where large conventional horizontal axis wind turbines (HAWTs) are too impractical to install and operate. A diffuser augmented wind turbine (DAWT) is one...

  14. Electrospray emitters For diffusion vacuum pumps

    E-Print Network [OSTI]

    Diaz Gómez Maqueo, Pablo (Pablo Ly)

    2011-01-01T23:59:59.000Z

    Following similar principles as regular diffusion vacuum pumps, an electrospray emitter is set to produce a jet of charged particles that will drag air molecules out of a volume. To be a feasible concept, the emitted ...

  15. Diffusion Simulation and Lifetime Calculation at RHIC

    SciTech Connect (OSTI)

    Abreu,N.P.; Fischer, W.; Luo, Y.; Robert-Demolaize, G.

    2009-01-02T23:59:59.000Z

    The beam lifetime is an important parameter for any storage ring. For protons in RHIC it is dominated by the non-linear nature of the head-on collisions that causes the particles to diffuse outside the stable area in phase space. In this report we show results from diffusion simulation and lifetime calculation for the 2006 and 2008 polarized proton runs in RHIC.

  16. Diffusion Preconditioner for Discontinuous Galerkin Transport Problems

    E-Print Network [OSTI]

    Barbu, Anthony Petru

    2011-08-08T23:59:59.000Z

    DIFFUSION PRECONDITIONER FOR DISCONTINUOUS GALERKIN TRANSPORT PROBLEMS A Thesis by ANTHONY PETRU BARBU Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment of the requirements for the degree of MASTER... OF SCIENCE May 2011 Major Subject: Nuclear Engineering DIFFUSION PRECONDITIONER FOR DISCONTINUOUS GALERKIN TRANSPORT PROBLEMS A Thesis by ANTHONY PETRU BARBU Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment...

  17. Mechanical Study of Copper Bonded at Low Temperature using Spark Plasma Sintering Process

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    is approximatively 6.47 MPa [7]. J. W. Elmer & al [8] have presented a diffusion bonding of high purity copper using a conventional furnace. A series of diffusion bonds was done to determine the relationship between bond strengthMechanical Study of Copper Bonded at Low Temperature using Spark Plasma Sintering Process Bassem

  18. Kinetics and Mechanisms of Pb(II) Sorption and Desorption at the

    E-Print Network [OSTI]

    Sparks, Donald L.

    ) spectroscopy revealed a Pb-Al bond distance of 3.40 Å, consistent with an inner-sphere bidentate bonding likely resulting from diffusion through micropores. Desorption at I ) 0.1 M and pH 6.50 was studied using (3, 5, 7-12). Three possible mechanisms for the slow reactions have been proposed: diffusion

  19. Mechanical Engineering ME 3720 FLUID MECHANICS

    E-Print Network [OSTI]

    Panchagnula, Mahesh

    Mechanical Engineering ME 3720 FLUID MECHANICS Pre-requisite: ME 2330 Co-requisite: ME 3210) to develop an understanding of the physical mechanisms and the mathematical models of fluid mechanics of fluid mechanics problems in engineering practice. The basic principles of fluid mechanics

  20. Diffuse Gas Condensation Induced by Variations of the Ionizing Flux

    E-Print Network [OSTI]

    Antonio Parravano; Catherine Pech

    1997-07-31T23:59:59.000Z

    The variation of an ionizing flux as a mechanism to stimulate the condensation of a diffuse gas is considered. To illustrate this effect, two situations are examined: one on the context of pregalactic conditions, and the other on the context of the actual interstellar medium. We focus our attention on flash-like variations; that is, during a ``short'' period of time the ionizing flux is enhanced in comparison to the pre- and post-flash values. In both cases the cause of the induced phase change is the same: the enhancement of the cooling rate by the increase in the electron density caused by the momentary increase of ionizing flux. After the passing of the flash, the cooling rate remains enhanced due to the ``inertia of the ionization''. In the first case (metal free gas) the cooling rate is enhanced due to the fact that the increase of the electron density makes possible the gas phase formation of H_2 by the creation of the intermediaries H^- and H^+_2. We show that after the passing of the photo-ionizing flash a cloud near thermo-chemical equilibrium at ~8000 K may be induced to increase its H_2 content by many orders of magnitude, causing a rapid decrease of its temperature to values as low as 100 K. In the second case (solar abundances gas) the dominant cooling mechanism of the warm neutral gas (the excitation of heavy ions by electron impacts) is proportional to the electron density. We show that, for the expected states of the warm interstellar gas, ionizing flashes may induce the phase transition from the warm to the cool phase. The results indicate that the mechanism of induced condensation studied here might play a relevant role in the gas evolution of the diffuse gas in both, the pregalactic and the actual interstellar medium conditions.

  1. Dispersive and diffusive-dispersive shock waves for nonconvex conservation laws

    E-Print Network [OSTI]

    El, G A; Shearer, M

    2015-01-01T23:59:59.000Z

    We compare the structure of solutions of Riemann problems for a conservation law with nonconvex (specifically, cubic) flux, regularized by two different mechanisms: 1) dispersion (in the modified Korteweg--de Vries (mKdV) equation); and 2) a combination of diffusion and dispersion (in the mKdV-Burgers equation). In the first case, the possible dynamics involve two qualitatively different types of expanding dispersive shock waves (DSWs), rarefaction waves (RWs) and kinks (smooth fronts). In the second case, in addition to RWs, there are travelling wave solutions approximating both classical (Lax) and nonclassical (undercompressive) shock waves. Despite the singular nature of the zero-diffusion limit and rather differing analytical approaches employed in the descriptions of dispersive and diffusive-dispersive regularization, the resulting comparison of the two cases reveals a number of striking parallels. In particular the mKdV kink solution is identified as an undercompressive DSW. Other prominent features, su...

  2. Fractal Location and Anomalous Diffusion Dynamics for Oil Wells from the KY Geological Survey

    E-Print Network [OSTI]

    Andrew, Keith; Andrew, Kevin A

    2009-01-01T23:59:59.000Z

    Utilizing data available from the Kentucky Geonet (KYGeonet.ky.gov) the fossil fuel mining locations created by the Kentucky Geological Survey geo-locating oil and gas wells are mapped using ESRI ArcGIS in Kentucky single plain 1602 ft projection. This data was then exported into a spreadsheet showing latitude and longitude for each point to be used for modeling at different scales to determine the fractal dimension of the set. Following the porosity and diffusivity studies of Tarafdar and Roy1 we extract fractal dimensions of the fossil fuel mining locations and search for evidence of scaling laws for the set of deposits. The Levy index is used to determine a match to a statistical mechanically motivated generalized probability function for the wells. This probability distribution corresponds to a solution of a dynamical anomalous diffusion equation of fractional order that describes the Levy paths which can be solved in the diffusion limit by the Fox H function ansatz.

  3. Snow-lines as probes of turbulent diffusion in protoplanetary discs

    E-Print Network [OSTI]

    Owen, James E

    2014-01-01T23:59:59.000Z

    Sharp chemical discontinuities can occur in protoplanetary discs, particularly at `snow-lines' where a gas-phase species freezes out to form ice grains. Such sharp discontinuities will diffuse out due to the turbulence suspected to drive angular momentum transport in accretion discs. We demonstrate that the concentration gradient - in the vicinity of the snow-line - of a species present outside a snow-line but destroyed inside is strongly sensitive to the level of turbulent diffusion (provided the chemical and transport time-scales are decoupled) and provides a direct measurement of the radial `Schmidt number' (the ratio of the angular momentum transport to radial turbulent diffusion). Taking as an example the tracer species N$_2$H$^+$, which is expected to be destroyed inside the CO snow-line (as recently observed in TW Hya) we show that ALMA observations possess significant angular resolution to constrain the Schmidt number. Since different turbulent driving mechanisms predict different Schmidt numbers, a d...

  4. NUMERICAL MODELLING OF AUTOGENOUS HEALING AND RECOVERY OF MECHANICAL PROPERTIES IN ULTRA-HIGH

    E-Print Network [OSTI]

    Boyer, Edmond

    , hydro-chemo- mechanical coupling ABSTRACT Cracks, caused by shrinkage or external loading, reduce. In this study, a hydro-chemo-mechanical model was developed to simulate autogenous healing by further hydration into water was modelled based on micro-mechanical observations. The diffusion process has been simulated

  5. Eddy diffusivities of inertial particles under gravity

    E-Print Network [OSTI]

    Marco Martins Afonso; Andrea Mazzino; Paolo Muratore-Ginanneschi

    2011-03-29T23:59:59.000Z

    The large-scale/long-time transport of inertial particles of arbitrary mass density under gravity is investigated by means of a formal multiple-scale perturbative expansion in the scale-separation parametre between the carrier flow and the particle concentration field. The resulting large-scale equation for the particle concentration is determined, and is found to be diffusive with a positive-definite eddy diffusivity. The calculation of the latter tensor is reduced to the resolution of an auxiliary differential problem, consisting of a coupled set of two differential equations in a (6+1)-dimensional coordinate system (3 space coordinates plus 3 velocity coordinates plus time). Although expensive, numerical methods can be exploited to obtain the eddy diffusivity, for any desirable non-perturbative limit (e.g. arbitrary Stokes and Froude numbers). The aforementioned large-scale equation is then specialized to deal with two different relevant perturbative limits: i) vanishing of both Stokes time and sedimenting particle velocity; ii) vanishing Stokes time and finite sedimenting particle velocity. Both asymptotics lead to a greatly simplified auxiliary differential problem, now involving only space coordinates and thus easy to be tackled by standard numerical techniques. Explicit, exact expressions for the eddy diffusivities have been calculated, for both asymptotics, for the class of parallel flows, both static and time-dependent. This allows us to investigate analytically the role of gravity and inertia on the diffusion process by varying relevant features of the carrier flow, as e.g. the form of its temporal correlation function. Our results exclude a universal role played by gravity and inertia on the diffusive behaviour: regimes of both enhanced and reduced diffusion may exist, depending on the detailed structure of the carrier flow.

  6. DIFFUSIVE ACCELERATION OF PARTICLES AT OBLIQUE, RELATIVISTIC, MAGNETOHYDRODYNAMIC SHOCKS

    SciTech Connect (OSTI)

    Summerlin, Errol J. [Heliospheric Physics Laboratory, Code 672, NASA's Goddard Space Flight Center, Greenbelt, MD 20770 (United States); Baring, Matthew G., E-mail: errol.summerlin@nasa.gov, E-mail: baring@rice.edu [Department of Physics and Astronomy, MS 108, Rice University, Houston, TX 77251 (United States)

    2012-01-20T23:59:59.000Z

    Diffusive shock acceleration (DSA) at relativistic shocks is expected to be an important acceleration mechanism in a variety of astrophysical objects including extragalactic jets in active galactic nuclei and gamma-ray bursts. These sources remain good candidate sites for the generation of ultrahigh energy cosmic rays. In this paper, key predictions of DSA at relativistic shocks that are germane to the production of relativistic electrons and ions are outlined. The technique employed to identify these characteristics is a Monte Carlo simulation of such diffusive acceleration in test-particle, relativistic, oblique, magnetohydrodynamic (MHD) shocks. Using a compact prescription for diffusion of charges in MHD turbulence, this approach generates particle angular and momentum distributions at any position upstream or downstream of the shock. Simulation output is presented for both small angle and large angle scattering scenarios, and a variety of shock obliquities including superluminal regimes when the de Hoffmann-Teller frame does not exist. The distribution function power-law indices compare favorably with results from other techniques. They are found to depend sensitively on the mean magnetic field orientation in the shock, and the nature of MHD turbulence that propagates along fields in shock environs. An interesting regime of flat-spectrum generation is addressed; we provide evidence for it being due to shock drift acceleration, a phenomenon well known in heliospheric shock studies. The impact of these theoretical results on blazar science is outlined. Specifically, Fermi Large Area Telescope gamma-ray observations of these relativistic jet sources are providing significant constraints on important environmental quantities for relativistic shocks, namely, the field obliquity, the frequency of scattering, and the level of field turbulence.

  7. Modeling biofilms with dual extracellular electron transfer mechanisms

    SciTech Connect (OSTI)

    Renslow, Ryan S.; Babauta, Jerome T.; Kuprat, Andrew P.; Schenk, Jim; Ivory, Cornelius; Fredrickson, Jim K.; Beyenal, Haluk

    2013-11-28T23:59:59.000Z

    Electrochemically active biofilms have a unique form of respiration in which they utilize solid external materials as their terminal electron acceptor for metabolism. Currently, two primary mechanisms have been identified for long-range extracellular electron transfer (EET): a diffusion- and a conduction-based mechanism. Evidence in the literature suggests that some biofilms, particularly Shewanella oneidensis, produce components requisite for both mechanisms. In this study, a generic model is presented that incorporates both diffusion- and conduction-based mechanisms and allows electrochemically active biofilms to utilize both simultaneously. The model was applied to Shewanella oneidensis and Geobacter sulfurreducens biofilms using experimentally generated data found the literature. Our simulation results showed that 1) biofilms having both mechanisms available, especially if they can interact, may have metabolic advantage over biofilms that can use only a single mechanism; 2) the thickness of Geobacter sulfurreducens biofilms is likely not limited by conductivity; 3) accurate intrabiofilm diffusion coefficient values are critical for current generation predictions; and 4) the local biofilm potential and redox potential are two distinct measurements and cannot be assumed to have identical values. Finally, we determined that cyclic and squarewave voltammetry are currently not good tools to determine the specific percentage of extracellular electron transfer mechanisms used by biofilms. The developed model will be a critical tool in designing experiments to explain EET mechanisms.

  8. diffusion-fundamentals The Open-Access Journal for the Basic Principles of Diffusion Theory, Experiment and Application

    E-Print Network [OSTI]

    Schuck, Götz

    × 10­10 H+ -Diffusion, symmetr. H-bond (TD) ~0.3 4 × 10­09 The method allowing us to isolate specificdiffusion-fundamentals The Open-Access Journal for the Basic Principles of Diffusion Theory, Experiment and Application www.diffusion-fundamentals.org, ISSN 1862-4138; © 2005-2010 Diffusion Fundamentals

  9. Mechanical & Aerospace Engineering

    E-Print Network [OSTI]

    Mechanical & Aerospace Engineering An experimental methodology is presented for mechanism verification of physics-based prognosis of mechanical damage, such as fatigue. The proposed experimental methodology includes multi-resolution in-situ mechanical testing, advanced imaging analysis, and mechanism

  10. HINDERED DIFFUSION OF ASPHALTENES AT ELEVATED TEMPERATURE AND PRESSURE

    SciTech Connect (OSTI)

    James A. Guin; Ganesh Ramakrishnan

    1999-10-07T23:59:59.000Z

    During this time period, experiments were performed to study the diffusion controlled uptake of quinoline and a coal asphaltene into porous carbon catalyst pellets. Cyclohexane and toluene were used as solvents for quinoline and the coal asphaltene respectively. The experiments were performed at 27 C and 75 C, at a pressure of 250 psi (inert gas) for the quinoline/cyclohexane system. For the coal asphaltene/toluene system, experiments were performed at 27 C, also at a pressure of 250 psi. These experiments were performed in a 20 cm{sup 3} microautoclave, the use of which is advantageous since it is economical from both a chemical procurement and waste disposal standpoint due to the small quantities of solvents and catalysts used. A C++ program was written to simulate data using a mathematical model which incorporated both diffusional and adsorption mechanisms. The simulation results showed that the mathematical model satisfactorily fitted the adsorptive diffusion of quinoline and the coal asphaltene onto a porous activated carbon. For the quinoline/cyclohexane system, the adsorption constant decreased with an increase in temperature. The adsorption constant for the coal asphaltene/toluene system at 27 C was found to be much higher than that of the quinoline/cyclohexane system at the same temperature. Apparently the coal asphaltenes have a much greater affinity for the surface of the carbon catalyst than is evidenced by the quinoline molecule.

  11. Mass fluctuations and diffusion in time-dependent random environments

    E-Print Network [OSTI]

    Giorgio Krstulovic; Rehab Bitane; Jeremie Bec

    2012-03-27T23:59:59.000Z

    A mass ejection model in a time-dependent random environment with both temporal and spatial correlations is introduced. When the environment has a finite correlation length, individual particle trajectories are found to diffuse at large times with a displacement distribution that approaches a Gaussian. The collective dynamics of diffusing particles reaches a statistically stationary state, which is characterized in terms of a fluctuating mass density field. The probability distribution of density is studied numerically for both smooth and non-smooth scale-invariant random environments. A competition between trapping in the regions where the ejection rate of the environment vanishes and mixing due to its temporal dependence leads to large fluctuations of mass. These mechanisms are found to result in the presence of intermediate power-law tails in the probability distribution of the mass density. For spatially differentiable environments, the exponent of the right tail is shown to be universal and equal to -3/2. However, at small values, it is found to depend on the environment. Finally, spatial scaling properties of the mass distribution are investigated. The distribution of the coarse-grained density is shown to posses some rescaling properties that depend on the scale, the amplitude of the ejection rate, and the H\\"older exponent of the environment.

  12. Developing the Galactic Diffuse Emission Model for the GLAST Large Area Telescope

    SciTech Connect (OSTI)

    Moskalenko, Igor V.; Strong, Andrew W.; Digel, Seth W.; Porter, Troy A.

    2007-04-30T23:59:59.000Z

    Diffuse emission is produced in energetic cosmic ray (CR) interactions, mainly protons and electrons, with the interstellar gas and radiation field and contains the information about particle spectra in distant regions of the Galaxy. It may also contain information about exotic processes such as dark matter annihilation, black hole evaporation etc. A model of the diffuse emission is important for determination of the source positions and spectra. Calculation of the Galactic diffuse continuum g-ray emission requires a model for CR propagation as the first step. Such a model is based on theory of particle transport in the interstellar medium as well as on many kinds of data provided by different experiments in Astrophysics and Particle and Nuclear Physics. Such data include: secondary particle and isotopic production cross sections, total interaction nuclear cross sections and lifetimes of radioactive species, gas mass calibrations and gas distribution in the Galaxy (H{sub 2}, H I, H II), interstellar radiation field, CR source distribution and particle spectra at the sources, magnetic field, energy losses, g-ray and synchrotron production mechanisms, and many other issues. We are continuously improving the GALPROP model and the code to keep up with a flow of new data. Improvement in any field may affect the Galactic diffuse continuum g-ray emission model used as a background model by the GLAST LAT instrument. Here we report about the latest improvements of the GALPROP and the diffuse emission model.

  13. The Diffuse Nature of Stromgren Spheres

    E-Print Network [OSTI]

    J. Ritzerveld

    2005-06-27T23:59:59.000Z

    In this Letter, we argue that the standard analytical derivations of properties of HII regions, such as the speed, shape and asymptotic position of ionisation fronts require a more precise treatment. These derivations use the on the spot approximation, which in effect ignores the diffuse component of the radiation field. We show that, in fact, HII regions are diffusion dominated. This has as a result that the morphology of inhomogeneous HII regions will be drastically different, because shadowing effects have a less profound impact on the apparent shape. Moreover, it will have influence on the propagation speed of ionisation fronts. We quantify our claims by analytically deriving the internal radiation structure of HII regions, taking diffusion fully into account for several different cosmologically relevant density distributions.

  14. Robust diffusion imaging framework for clinical studies

    E-Print Network [OSTI]

    Maximov, Ivan I; Neuner, Irene; Shah, N Jon

    2015-01-01T23:59:59.000Z

    Clinical diffusion imaging requires short acquisition times and good image quality to permit its use in various medical applications. In turn, these demands require the development of a robust and efficient post-processing framework in order to guarantee useful and reliable results. However, multiple artefacts abound in in vivo measurements; from either subject such as cardiac pulsation, bulk head motion, respiratory motion and involuntary tics and tremor, or imaging hardware related problems, such as table vibrations, etc. These artefacts can severely degrade the resulting images and render diffusion analysis difficult or impossible. In order to overcome these problems, we developed a robust and efficient framework enabling the use of initially corrupted images from a clinical study. At the heart of this framework is an improved least trimmed squares diffusion tensor estimation algorithm that works well with severely degraded datasets with low signal-to-noise ratio. This approach has been compared with other...

  15. Effect of Diffusion on Bunched Beam Echo

    SciTech Connect (OSTI)

    Stupakov, G.V.; Chao, A.W.; /SLAC

    2011-09-01T23:59:59.000Z

    When a beam receives a dipole kick, its centroid signal decoheres due to the betatron tune spread in the beam. Long after the signal has decohered, however, a followup quadrupole kick to the beam brings a pronounced echo back to the centroid signal. This echo effect has been analyzed for the case of a bunched beam in Ref. [1]. In this work, the perturbation calculation of Ref. [1] is extended to include a diffusion in betatron amplitude. The effect of diffusion on the magnitude of the echo is then parameterized and studied.

  16. Self- and zinc diffusion in gallium antimonide

    SciTech Connect (OSTI)

    Nicols, Samuel Piers

    2002-03-26T23:59:59.000Z

    The technological age has in large part been driven by the applications of semiconductors, and most notably by silicon. Our lives have been thoroughly changed by devices using the broad range of semiconductor technology developed over the past forty years. Much of the technological development has its foundation in research carried out on the different semiconductors whose properties can be exploited to make transistors, lasers, and many other devices. While the technological focus has largely been on silicon, many other semiconductor systems have applications in industry and offer formidable academic challenges. Diffusion studies belong to the most basic studies in semiconductors, important from both an application as well as research standpoint. Diffusion processes govern the junctions formed for device applications. As the device dimensions are decreased and the dopant concentrations increased, keeping pace with Moore's Law, a deeper understanding of diffusion is necessary to establish and maintain the sharp dopant profiles engineered for optimal device performance. From an academic viewpoint, diffusion in semiconductors allows for the study of point defects. Very few techniques exist which allow for the extraction of as much information of their properties. This study focuses on diffusion in the semiconductor gallium antimonide (GaSb). As will become clear, this compound semiconductor proves to be a powerful one for investigating both self- and foreign atom diffusion. While the results have direct applications for work on GaSb devices, the results should also be taken in the broader context of III-V semiconductors. Results here can be compared and contrasted to results in systems such as GaAs and even GaN, indicating trends within this common group of semiconductors. The results also have direct importance for ternary and quaternary semiconductor systems used in devices such as high speed InP/GaAsSb/InP double heterojunction bipolar transistors (DHBT) [Dvorak, (2001)]. Many of the findings which will be reported here were previously published in three journal articles. Hartmut Bracht was the lead author on two articles on self-diffusion studies in GaSb [Bracht, (2001), (2000)], while this report's author was the lead author on Zn diffusion results [Nicols, (2001)]. Much of the information contained herein can be found in those articles, but a more detailed treatment is presented here.

  17. Fractal diffusion coefficient from dynamical zeta functions

    E-Print Network [OSTI]

    G. Cristadoro

    2005-09-28T23:59:59.000Z

    Dynamical zeta functions provide a powerful method to analyze low dimensional dynamical systems when the underlying symbolic dynamics is under control. On the other hand even simple one dimensional maps can show an intricate structure of the grammar rules that may lead to a non smooth dependence of global observable on parameters changes. A paradigmatic example is the fractal diffusion coefficient arising in a simple piecewise linear one dimensional map of the real line. Using the Baladi-Ruelle generalization of the Milnor-Thurnston kneading determinant we provide the exact dynamical zeta function for such a map and compute the diffusion coefficient from its smallest zero.

  18. Forecasting Turbulent Modes with Nonparametric Diffusion Models

    E-Print Network [OSTI]

    Tyrus Berry; John Harlim

    2015-01-27T23:59:59.000Z

    This paper presents a nonparametric diffusion modeling approach for forecasting partially observed noisy turbulent modes. The proposed forecast model uses a basis of smooth functions (constructed with the diffusion maps algorithm) to represent probability densities, so that the forecast model becomes a linear map in this basis. We estimate this linear map by exploiting a previously established rigorous connection between the discrete time shift map and the semi-group solution associated to the backward Kolmogorov equation. In order to smooth the noisy data, we apply diffusion maps to a delay embedding of the noisy data, which also helps to account for the interactions between the observed and unobserved modes. We show that this delay embedding biases the geometry of the data in a way which extracts the most predictable component of the dynamics. The resulting model approximates the semigroup solutions of the generator of the underlying dynamics in the limit of large data and in the observation noise limit. We will show numerical examples on a wide-range of well-studied turbulent modes, including the Fourier modes of the energy conserving Truncated Burgers-Hopf (TBH) model, the Lorenz-96 model in weakly chaotic to fully turbulent regimes, and the barotropic modes of a quasi-geostrophic model with baroclinic instabilities. In these examples, forecasting skills of the nonparametric diffusion model are compared to a wide-range of stochastic parametric modeling approaches, which account for the nonlinear interactions between the observed and unobserved modes with white and colored noises.

  19. Diffusion in Energy Conserving Coupled Maps

    E-Print Network [OSTI]

    Jean Bricmont; Antti Kupiainen

    2012-09-09T23:59:59.000Z

    We consider a dynamical system consisting of subsystems indexed by a lattice. Each subsystem has one conserved degree of freedom ("energy") the rest being uniformly hyperbolic. The subsystems are weakly coupled together so that the sum of the subsystem energies remains conserved. We prove that the subsystem energies satisfy the diffusion equation in a suitable scaling limit.

  20. Ternary gas mixture for diffuse discharge switch

    DOE Patents [OSTI]

    Christophorou, Loucas G. (Oak Ridge, TN); Hunter, Scott R. (Oak Ridge, TN)

    1988-01-01T23:59:59.000Z

    A new diffuse discharge gas switch wherein a mixture of gases is used to take advantage of desirable properties of the respective gases. There is a conducting gas, an insulating gas, and a third gas that has low ionization energy resulting in a net increase in the number of electrons available to produce a current.

  1. Mathematical analysis for fractional diffusion equations: forward

    E-Print Network [OSTI]

    Boyer, Franck

    or dumping WasteGroundwater flow Base rock Underground storage Soil gapsmicro scale about 100m Field: macro-Diffusion equation Result of Field Test (Adams& Gelhar, 1992) t0 t1 t2 t3 t0 Pollution source Model Prediction Univ. #12;· Determination of contamination source t u = u + F We need detailed mathematical researches

  2. Correcting the diffusion approximation at the boundary

    E-Print Network [OSTI]

    Kim, Arnold D.

    , 2011 The diffusion approximation to the radiative transport equation applies for light that has solutions of the radiative transport equation to evaluate each of their accuracy. Nonetheless, nearly all transport equation · I þ aI þ sLI ¼ 0; ð1:1� governs continuous light propagation in tissues [1

  3. Original article Mannitol enhances intracellular calcium diffusion

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    concentration-dependent increase in the amount of calcium absor- bed in 1 h from 8 cm long ileal loops prepared-enhanced movement of calcium out of the loop cannot have utilized the paracellular pathway, inasmuch as the luminalOriginal article Mannitol enhances intracellular calcium diffusion in the rat ileum ­ a hypothesis

  4. Metal Nitride Diffusion Barriers for Copper Interconnects

    E-Print Network [OSTI]

    Araujo, Roy A.

    2010-01-14T23:59:59.000Z

    of copper into silicon, which is primarily through grain boundaries. This dissertation reports the processing of high quality stoichiometric thin films of TiN, TaN and HfN, and studies their Cu diffusion barrier properties. Epitaxial metastable cubic TaN (B1...

  5. Open Source Software: Management, Diffusion and Competition

    E-Print Network [OSTI]

    Kouroupetroglou, Georgios

    and competitive environment such as the ICT market. 1 Introduction OSS is an alternative model of software has introduced an innovative model of software development, based on self-organized communitiesOpen Source Software: Management, Diffusion and Competition Spyridoula Lakkaé National

  6. 728 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 34, NO. 3, JUNE 2006 The Electron Diffusion Coefficient in Energy

    E-Print Network [OSTI]

    Kaganovich, Igor

    Coefficient in Energy in Bounded Collisional Plasmas Lev D. Tsendin Abstract--The electron energies in typical, the momentum relaxation in collisions with neutrals is sig- nificantly faster than the energy relaxation due be de- scribed by a diffusion coefficient in energy . Both collisional and stochastic heating mechanisms

  7. Creep damage mechanisms in composites

    SciTech Connect (OSTI)

    Nutt, S.R.

    1994-10-17T23:59:59.000Z

    During the past year, research has focused on processing and characterization of intermetallic composites synthesized by plasma spray deposition. This versatile process allows rapid synthesis of a variety of different composite systems with potential applications for coatings, functionally gradient materials, rapid proto-typing and 3d printing, as well as near-net-shape processing of complex shapes. We have been pursuing an experimental program of research aimed at a fundamental understanding of the microstructural processes involved in the synthesis of intermetallic composites, including diffusion, heat transfer, grain boundary migration, and the dependence of these phenomena on deposition parameters. The work has been motivated by issues arising from composite materials manufacturing technologies. Recent progress is described in section B on the following topics: (1) Reactive atomization and deposition of intermetallic composites (Ni3Al); (2) Reactive synthesis of MoSi2-SiC composites; (3) Mechanical alloying of nanocrystalline alloys; (4) Tensile creep deformation of BMAS glass-ceramic composites.

  8. Formation mechanism for polycyclic aromatic hydrocarbons in methane flames

    E-Print Network [OSTI]

    Sattler, Klaus

    Formation mechanism for polycyclic aromatic hydrocarbons in methane flames K. Siegmanna) Swiss 96822 Received 24 August 1999; accepted 13 October 1999 A laminar diffusion flame of methane exhausts,7­17 coal-fired, electricity generating power plants,18,19 tobacco smoke,20 residential wood

  9. Water Management in A PEMFC: Water Transport Mechanism and Material

    E-Print Network [OSTI]

    Kandlikar, Satish

    Water Management in A PEMFC: Water Transport Mechanism and Material Degradation in Gas Diffusion on the water management of the PEMFC, namely the transport of product water (both liquid and vapor its water management performance and func- tion as indicators of the degradation of GDL material

  10. Probing the brain’s white matter with diffusion MRI and a tissue dependent diffusion model 

    E-Print Network [OSTI]

    Piatkowski, Jakub Przemyslaw

    2014-06-27T23:59:59.000Z

    While diffusion MRI promises an insight into white matter microstructure in vivo, the axonal pathways that connect different brain regions together can only partially be segmented using current methods. Here we present ...

  11. Solar Resonant Diffusion Waves as a Driver of Terrestrial Climate Change

    E-Print Network [OSTI]

    Robert Ehrlich

    2007-01-04T23:59:59.000Z

    A theory is described based on resonant thermal diffusion waves in the sun that appears to explain many details of the paleotemperature record for the last 5.3 million years. These include the observed periodicities, the relative strengths of each observed cycle, and the sudden emergence in time for the 100 thousand year cycle. Other prior work suggesting a link between terrestrial paleoclimate and solar luminosity variations has not provided any specific mechanism. The particular mechanism described here has been demonstrated empirically, although not previously invoked in the solar context. The theory also lacks most of the problems associated with Milankovitch cycles.

  12. Mechanical and Aerospace Engineering

    E-Print Network [OSTI]

    Mechanical and Aerospace Engineering seminar Three Dimensional Traction Force Microscopy with Applications in Cell Mechanics abstract The interactions between biochemical and mechanical signals during-dimensional measurement techniques are needed to investigate the effect of mechanical properties of the substrate

  13. Mechanical Engineer Company Description

    E-Print Network [OSTI]

    Kostic, Milivoje M.

    Mechanical Engineer Company Description Control Solutions Inc. is a small, dynamic, and rapidly. Position Description The Mechanical Engineer is responsible for all aspects associated with the mechanical enclosures, brackets, cabling assemblies among others. Systems include mechanisms, sensors, hydraulics, among

  14. MECHANICAL ENGINEERING Ross Schlueter

    E-Print Network [OSTI]

    MECHANICAL ENGINEERING Ross Schlueter Engineering Deputy For Mechanical Engineering Russ Wells Mechanical Engineering Department Deputy ELECTRONICS, SOFTWARE & INSTRUMENTATION ENGINEERING Henrik von Der Sen Mechanical Admin. Assist. Joan Wolter Electronics Admin. Assist. Marilyn Wong Division Admin

  15. E-Print Network 3.0 - altered water diffusivity Sample Search...

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

    Emory University Collection: Materials Science ; Physics 47 Oxygen diffusion in titanite: Lattice diffusion and fast-path diffusion in single crystals Summary: , with little...

  16. Shell Model for Atomistic Simulation of Lithium Diffusion in...

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

    Shell Model for Atomistic Simulation of Lithium Diffusion in Mixed MnTi Oxides. Shell Model for Atomistic Simulation of Lithium Diffusion in Mixed MnTi Oxides. Abstract: Mixed...

  17. A piecewise linear finite element discretization of the diffusion equation

    E-Print Network [OSTI]

    Bailey, Teresa S

    2006-10-30T23:59:59.000Z

    it discretizes the diffusion equation on an arbitrary polyhedral mesh. We implemented our method in the KULL software package being developed at Lawrence Livermore National Laboratory. This code previously utilized Palmer's method as its diffusion solver, which...

  18. Modelling of unidirectional thermal diffusers in shallow water

    E-Print Network [OSTI]

    Lee, Joseph Hun-Wei

    1977-01-01T23:59:59.000Z

    This study is an experimental and theoretical investigation of the temperature field and velocity field induced by a unidirectional thermal diffuser in shallow water. A multiport thermal diffuser is essentially a pipe laid ...

  19. Imaging Intrinsic Diffusion of Bridge-Bonded Oxygen Vacancies...

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

    Intrinsic Diffusion of Bridge-Bonded Oxygen Vacancies on TiO2(110). Imaging Intrinsic Diffusion of Bridge-Bonded Oxygen Vacancies on TiO2(110). Abstract: Since oxygen atom...

  20. Sensitivity of climate change to diapycnal diffusivity in the ocean

    E-Print Network [OSTI]

    Dalan, Fabio, 1975-

    2003-01-01T23:59:59.000Z

    The diapycnal diffusivity of the ocean is one of the least known parameters in cur- rent climate models. Measurements of this diffusivity are sparse and insufficient for compiling a global map. Inferences from inverse ...

  1. Quantitative analysis of cerebral white matter anatomy from diffusion MRI

    E-Print Network [OSTI]

    Maddah, Mahnaz

    2008-01-01T23:59:59.000Z

    In this thesis we develop algorithms for quantitative analysis of white matter fiber tracts from diffusion MRI. The presented methods enable us to look at the variation of a diffusion measure along a fiber tract in a single ...

  2. CODED SPECTROSCOPY FOR ETHANOL DETECTION IN DIFFUSE, FLUORESCENT MEDIA

    E-Print Network [OSTI]

    ABSTRACT CODED SPECTROSCOPY FOR ETHANOL DETECTION IN DIFFUSE, FLUORESCENT MEDIA by Scott Thomas Mc FOR ETHANOL DETECTION IN DIFFUSE, FLUORESCENT MEDIA by Scott Thomas McCain Department of Electrical

  3. Ballistic vs. diffusive heat transfer across nanoscopic films of layered crystals

    SciTech Connect (OSTI)

    Shen, Meng; Keblinski, Pawel, E-mail: keblip@rpi.edu [Department of Materials Science and Engineering, and Rensselaer Nanotechnology Center, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2014-04-14T23:59:59.000Z

    We use non-equilibrium molecular dynamics to study the heat transfer mechanism across sandwich interfacial structures of Si/n-atomic-layers/Si, with 1???n???20 and atomic layers composed of WSe{sub 2} and/or graphene. In the case of WSe{sub 2} sheets, we observe that the thermal resistance of the sandwich structure is increasing almost linearly with the number of WSe{sub 2} sheets, n, indicating a diffusive phonon transport mechanism. By contrast in the case of n graphene layers, the interfacial thermal resistance is more or less independent on the number of layers for 1???n???10, and is associated with ballistic phonon transport mechanism. We attribute the diffusive heat transfer mechanism across WSe{sub 2} sheets to abundant low frequency and low group velocity optical modes that carry most of the heat across the interface. By contrast, in graphene, acoustic modes dominate the thermal transport across the interface and render a ballistic heat flow mechanism.

  4. LETTRES A LA RDACTION DIFFUSION LASTIQUE DES PHOTONS

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    spectrometrie par scintillation 6choue, 6 cause des empilements de photons diffus6s de basse énergie. FIG. 1

  5. Convergence Speed of GARCH Option Price to Diffusion Option Price

    E-Print Network [OSTI]

    Wang, Yazhen

    Convergence Speed of GARCH Option Price to Diffusion Option Price Jin-Chuan Duan National constructed GARCH model will weakly converge to a bi- variate diffusion. Naturally the European option price under the GARCH model will also converge to its bivariate diffusion counterpart. This paper investigates

  6. Diffusion Bonding Aluminium Alloys and Composites: New Approaches and Modelling

    E-Print Network [OSTI]

    Cambridge, University of

    Diffusion Bonding Aluminium Alloys and Composites: New Approaches and Modelling Amir A. Shirzadi of the research, two new methods for TLP diffusion bonding of aluminium-based composites (aluminium alloys diffusion bonding and hot isostatic pressing without encapsulation. It allows the fabrication of intricate

  7. EFFECT OF BROWNIAN AND THERMOPHORETIC DIFFUSIONS OF NANOPARTICLES ON

    E-Print Network [OSTI]

    Zhang, Yuwen

    EFFECT OF BROWNIAN AND THERMOPHORETIC DIFFUSIONS OF NANOPARTICLES ON NONEQUILIBRIUM HEAT CONDUCTION of Brownian and thermophoretic diffusions on nonequilibrium heat conduction in a nanofluid layer with periodic, and period of the surface heat flux. Effects of Brownian and thermophoretic diffusions of nanoparticles

  8. Nonlinear analysis of a reaction-diffusion system: Amplitude equations

    SciTech Connect (OSTI)

    Zemskov, E. P., E-mail: zemskov@ccas.ru [Russian Academy of Sciences, Dorodnicyn Computing Center (Russian Federation)

    2012-10-15T23:59:59.000Z

    A reaction-diffusion system with a nonlinear diffusion term is considered. Based on nonlinear analysis, the amplitude equations are obtained in the cases of the Hopf and Turing instabilities in the system. Turing pattern-forming regions in the parameter space are determined for supercritical and subcritical instabilities in a two-component reaction-diffusion system.

  9. ORIGINAL PAPER Assimilation and diffusion during xenolith-magma

    E-Print Network [OSTI]

    Podladchikov, Yuri

    (responsible for the linear mixing trends) and (2) diffusion-controlled redistribution of elements between bothORIGINAL PAPER Assimilation and diffusion during xenolith-magma interaction: a case study the assimilation of granitic melt. Linear mixing trends on Harker diagrams for most network-forming and mainly slow-diffusing

  10. Oxygen diffusion and reactivity at low temperature on bare amorphous olivine-type silicate

    SciTech Connect (OSTI)

    Minissale, M., E-mail: marco.minissale@obspm.fr; Congiu, E.; Dulieu, F. [LERMA-LAMAp, Université de Cergy-Pontoise, Observatoire de Paris, ENS, UPMC, UMR 8112 du CNRS, 5 Mail Gay Lussac, 95000 Cergy Pontoise Cedex (France)] [LERMA-LAMAp, Université de Cergy-Pontoise, Observatoire de Paris, ENS, UPMC, UMR 8112 du CNRS, 5 Mail Gay Lussac, 95000 Cergy Pontoise Cedex (France)

    2014-02-21T23:59:59.000Z

    The mobility of O atoms at very low temperatures is not generally taken into account, despite O diffusion would add to a series of processes leading to the observed rich molecular diversity in space. We present a study of the mobility and reactivity of O atoms on an amorphous silicate surface. Our results are in the form of reflection absorption infrared spectroscopy and temperature-programmed desorption spectra of O{sub 2} and O{sub 3} produced via two pathways: O + O and O{sub 2} + O, investigated in a submonolayer regime and in the range of temperature between 6.5 and 30 K. All the experiments show that ozone is formed efficiently on silicate at any surface temperature between 6.5 and 30 K. The derived upper limit for the activation barriers of O + O and O{sub 2} + O reactions is ?150 K/k{sub b}. Ozone formation at low temperatures indicates that fast diffusion of O atoms is at play even at 6.5 K. Through a series of rate equations included in our model, we also address the reaction mechanisms and show that neither the Eley–Rideal nor the hot atom mechanisms alone can explain the experimental values. The rate of diffusion of O atoms, based on modeling results, is much higher than the one generally expected, and the diffusive process proceeds via the Langmuir-Hinshelwood mechanism enhanced by tunnelling. In fact, quantum effects turn out to be a key factor that cannot be neglected in our simulations. Astrophysically, efficient O{sub 3} formation on interstellar dust grains would imply the presence of huge reservoirs of oxygen atoms. Since O{sub 3} is a reservoir of elementary oxygen, and also of OH via its hydrogenation, it could explain the observed concomitance of CO{sub 2} and H{sub 2}O in the ices.

  11. Diffusion limited reactions in confined environments

    E-Print Network [OSTI]

    Jeremy D. Schmit; Ercan Kamber; Jané Kondev

    2007-11-19T23:59:59.000Z

    We study the effect of confinement on diffusion limited bimolecular reactions within a lattice model where a small number of reactants diffuse amongst a much larger number of inert particles. When the number of inert particles is held constant the rate of the reaction is slow for small reaction volumes due to limited mobility from crowding, and for large reaction volumes due to the reduced concentration of the reactants. The reaction rate proceeds fastest at an intermediate confinement corresponding to volume fraction near 1/2 and 1/3 in two and three dimensions, respectively. We generalize the model to off-lattice systems with hydrodynamic coupling and predict that the optimal reaction rate for monodisperse colloidal systems occurs when the volume fraction is ~0.18. Finally, we discuss the application of our model to bimolecular reactions inside cells as well as the dynamics of confined polymers.

  12. Diffusion barriers in modified air brazes

    DOE Patents [OSTI]

    Weil, Kenneth Scott; Hardy, John S; Kim, Jin Yong; Choi, Jung-Pyung

    2013-04-23T23:59:59.000Z

    A method for joining two ceramic parts, or a ceramic part and a metal part, and the joint formed thereby. The method provides two or more parts, a braze consisting of a mixture of copper oxide and silver, a diffusion barrier, and then heats the braze for a time and at a temperature sufficient to form the braze into a bond holding the two or more parts together. The diffusion barrier is an oxidizable metal that forms either a homogeneous component of the braze, a heterogeneous component of the braze, a separate layer bordering the braze, or combinations thereof. The oxidizable metal is selected from the group Al, Mg, Cr, Si, Ni, Co, Mn, Ti, Zr, Hf, Pt, Pd, Au, lanthanides, and combinations thereof.

  13. Diffusion barriers in modified air brazes

    DOE Patents [OSTI]

    Weil, Kenneth Scott (Richland, WA); Hardy, John S. (Richland, WA); Kim, Jin Yong (Richland, WA); Choi, Jung-Pyung (Richland, WA)

    2010-04-06T23:59:59.000Z

    A method for joining two ceramic parts, or a ceramic part and a metal part, and the joint formed thereby. The method provides two or more parts, a braze consisting of a mixture of copper oxide and silver, a diffusion barrier, and then heats the braze for a time and at a temperature sufficient to form the braze into a bond holding the two or more parts together. The diffusion barrier is an oxidizable metal that forms either a homogeneous component of the braze, a heterogeneous component of the braze, a separate layer bordering the braze, or combinations thereof. The oxidizable metal is selected from the group Al, Mg, Cr, Si, Ni, Co, Mn, Ti, Zr, Hf, Pt, Pd, Au, lanthanides, and combinations thereof.

  14. Methodology and apparatus for diffuse photon mimaging

    DOE Patents [OSTI]

    Feng, Shechao C. (Los Angeles, CA); Zeng, Fanan (Los Angeles, CA); Zhao, Hui-Lin (Los Angeles, CA)

    1997-12-09T23:59:59.000Z

    Non-invasive near infrared optical medical imaging devices for both hematoma detection in the brain and early tumor detection in the breast is achieved using image reconstruction which allows a mapping of the position dependent contrast diffusive propagation constants, which are related to the optical absorption coefficient and scattering coefficient in the tissue, at near infrared wavelengths. Spatial resolutions in the range of 5 mm for adult brain sizes and breast sizes can be achieved. The image reconstruction utilizes WKB approximation on most probable diffusion paths which has as lowest order approximation the straight line-of-sight between the plurality of sources and the plurality of detectors. The WKB approximation yields a set of linear equations in which the contrast optical absorption coefficients are the unknowns and for which signals can be generated to produce a pixel map of the contrast optical resolution of the scanned tissue.

  15. Methodology and apparatus for diffuse photon imaging

    DOE Patents [OSTI]

    Feng, S.C.; Zeng, F.; Zhao, H.L.

    1997-12-09T23:59:59.000Z

    Non-invasive near infrared optical medical imaging devices for both hematoma detection in the brain and early tumor detection in the breast is achieved using image reconstruction which allows a mapping of the position dependent contrast diffusive propagation constants, which are related to the optical absorption coefficient and scattering coefficient in the tissue, at near infrared wavelengths. Spatial resolutions in the range of 5 mm for adult brain sizes and breast sizes can be achieved. The image reconstruction utilizes WKB approximation on most probable diffusion paths which has as lowest order approximation the straight line-of-sight between the plurality of sources and the plurality of detectors. The WKB approximation yields a set of linear equations in which the contrast optical absorption coefficients are the unknowns and for which signals can be generated to produce a pixel map of the contrast optical resolution of the scanned tissue. 58 figs.

  16. Glass Membrane For Controlled Diffusion Of Gases

    DOE Patents [OSTI]

    Shelby, James E. (Alfred Station, NY); Kenyon, Brian E. (Pittsburgh, PA)

    2001-05-15T23:59:59.000Z

    A glass structure for controlled permeability of gases includes a glass vessel. The glass vessel has walls and a hollow center for receiving a gas. The glass vessel contains a metal oxide dopant formed with at least one metal selected from the group consisting of transition metals and rare earth metals for controlling diffusion of the gas through the walls of the glass vessel. The vessel releases the gas through its walls upon exposure to a radiation source.

  17. Diffuse-dynamic multiparameter diffractometry: A review

    SciTech Connect (OSTI)

    Molodkin, V. B., E-mail: molodkn@imp.kiev.ua; Shpak, A. P. [National Academy of Sciences of Ukraine, Institute of Metal Physics (Ukraine); Kovalchuk, M. V.; Nosik, V. L. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Machulin, V. F. [National Academy of Sciences of Ukraine, Institute of Semiconductor Physics (Ukraine)

    2010-12-15T23:59:59.000Z

    The results reported at the Conference on Application of X-Rays, Synchrotron Radiation, Neutrons, and Electrons in Nano-, Bio-, Information-, and Cognitive Technologies (RSNE-NBIC 2009) are briefly reviewed. This review is based on a cycle of studies [1-6] where a new method for studying the structure of real crystals-diffuse-dynamic multiparameter diffractometry (DDMD)-was proposed and substantiated.

  18. Diffusion method of seperating gaseous mixtures

    DOE Patents [OSTI]

    Pontius, Rex B. (Rochester, NY)

    1976-01-01T23:59:59.000Z

    A method of effecting a relatively large change in the relative concentrations of the components of a gaseous mixture by diffusion which comprises separating the mixture into heavier and lighter portions according to major fraction mass recycle procedure, further separating the heavier portions into still heavier subportions according to a major fraction mass recycle procedure, and further separating the lighter portions into still lighter subportions according to a major fraction equilibrium recycle procedure.

  19. Gas mixture for diffuse-discharge switch

    DOE Patents [OSTI]

    Christophorou, L.G.; Carter, J.G.; Hunter, S.R.

    1982-08-31T23:59:59.000Z

    Gaseous medium in a diffuse-discharge switch of a high-energy pulse generator is formed of argon combined with a compound selected from the group consisting of CF/sub 4/, C/sub 2/F/sub 6/, C/sub 3/F/sub 8/, n-C/sub 4/F/sub 10/, WF/sub 6/, (CF/sub 3/)/sub 2/S and (CF/sub 3/)/sub 2/O.

  20. Uranium enrichment export control guide: Gaseous diffusion

    SciTech Connect (OSTI)

    Not Available

    1989-09-01T23:59:59.000Z

    This document was prepared to serve as a guide for export control officials in their interpretation, understanding, and implementation of export laws that relate to the Zangger International Trigger List for gaseous diffusion uranium enrichment process components, equipment, and materials. Particular emphasis is focused on items that are especially designed or prepared since export controls are required for these by States that are party to the International Nuclear Nonproliferation Treaty.

  1. Diffuse-Charge Dynamics in Electrochemical Systems

    E-Print Network [OSTI]

    Martin Z. Bazant; Katsuyo Thornton; Armand Ajdari

    2004-01-08T23:59:59.000Z

    The response of a model micro-electrochemical system to a time-dependent applied voltage is analyzed. The article begins with a fresh historical review including electrochemistry, colloidal science, and microfluidics. The model problem consists of a symmetric binary electrolyte between parallel-plate, blocking electrodes which suddenly apply a voltage. Compact Stern layers on the electrodes are also taken into account. The Nernst-Planck-Poisson equations are first linearized and solved by Laplace transforms for small voltages, and numerical solutions are obtained for large voltages. The ``weakly nonlinear'' limit of thin double layers is then analyzed by matched asymptotic expansions in the small parameter $\\epsilon = \\lambda_D/L$, where $\\lambda_D$ is the screening length and $L$ the electrode separation. At leading order, the system initially behaves like an RC circuit with a response time of $\\lambda_D L / D$ (not $\\lambda_D^2/D$), where $D$ is the ionic diffusivity, but nonlinearity violates this common picture and introduce multiple time scales. The charging process slows down, and neutral-salt adsorption by the diffuse part of the double layer couples to bulk diffusion at the time scale, $L^2/D$. In the ``strongly nonlinear'' regime (controlled by a dimensionless parameter resembling the Dukhin number), this effect produces bulk concentration gradients, and, at very large voltages, transient space charge. The article concludes with an overview of more general situations involving surface conduction, multi-component electrolytes, and Faradaic processes.

  2. A diffuse interface model with immiscibility preservation

    SciTech Connect (OSTI)

    Tiwari, Arpit, E-mail: atiwari2@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)] [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Freund, Jonathan B., E-mail: jbfreund@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Pantano, Carlos [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)] [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

    2013-11-01T23:59:59.000Z

    A new, simple, and computationally efficient interface capturing scheme based on a diffuse interface approach is presented for simulation of compressible multiphase flows. Multi-fluid interfaces are represented using field variables (interface functions) with associated transport equations that are augmented, with respect to an established formulation, to enforce a selected interface thickness. The resulting interface region can be set just thick enough to be resolved by the underlying mesh and numerical method, yet thin enough to provide an efficient model for dynamics of well-resolved scales. A key advance in the present method is that the interface regularization is asymptotically compatible with the thermodynamic mixture laws of the mixture model upon which it is constructed. It incorporates first-order pressure and velocity non-equilibrium effects while preserving interface conditions for equilibrium flows, even within the thin diffused mixture region. We first quantify the improved convergence of this formulation in some widely used one-dimensional configurations, then show that it enables fundamentally better simulations of bubble dynamics. Demonstrations include both a spherical-bubble collapse, which is shown to maintain excellent symmetry despite the Cartesian mesh, and a jetting bubble collapse adjacent a wall. Comparisons show that without the new formulation the jet is suppressed by numerical diffusion leading to qualitatively incorrect results.

  3. Interactive Volume Rendering of Diffusion Tensor Data

    SciTech Connect (OSTI)

    Hlawitschka, Mario; Weber, Gunther; Anwander, Alfred; Carmichael, Owen; Hamann, Bernd; Scheuermann, Gerik

    2007-03-30T23:59:59.000Z

    As 3D volumetric images of the human body become an increasingly crucial source of information for the diagnosis and treatment of a broad variety of medical conditions, advanced techniques that allow clinicians to efficiently and clearly visualize volumetric images become increasingly important. Interaction has proven to be a key concept in analysis of medical images because static images of 3D data are prone to artifacts and misunderstanding of depth. Furthermore, fading out clinically irrelevant aspects of the image while preserving contextual anatomical landmarks helps medical doctors to focus on important parts of the images without becoming disoriented. Our goal was to develop a tool that unifies interactive manipulation and context preserving visualization of medical images with a special focus on diffusion tensor imaging (DTI) data. At each image voxel, DTI provides a 3 x 3 tensor whose entries represent the 3D statistical properties of water diffusion locally. Water motion that is preferential to specific spatial directions suggests structural organization of the underlying biological tissue; in particular, in the human brain, the naturally occuring diffusion of water in the axon portion of neurons is predominantly anisotropic along the longitudinal direction of the elongated, fiber-like axons [MMM+02]. This property has made DTI an emerging source of information about the structural integrity of axons and axonal connectivity between brain regions, both of which are thought to be disrupted in a broad range of medical disorders including multiple sclerosis, cerebrovascular disease, and autism [Mos02, FCI+01, JLH+99, BGKM+04, BJB+03].

  4. Multicomponent Gas Diffusion in Porous Electrodes

    E-Print Network [OSTI]

    Fu, Yeqing; Dutta, Abhijit; Mohanram, Aravind; Pietras, John D; Bazant, Martin Z

    2014-01-01T23:59:59.000Z

    Multicomponent gas transport is investigated with unprecedented precision by AC impedance analysis of porous YSZ anode-supported solid oxide fuel cells. A fuel gas mixture of H2-H2O-N2 is fed to the anode, and impedance data are measured across the range of hydrogen partial pressure (10-100%) for open circuit conditions at three temperatures (800C, 850C and 900C) and for 300mA applied current at 800C. For the first time, analytical formulae for the diffusion resistance (Rb) of three standard models of multicomponent gas transport (Fick, Stefan-Maxwell, and Dusty Gas) are derived and tested against the impedance data. The tortuosity is the only fitting parameter since all the diffusion coefficients are known. Only the Dusty Gas model leads to a remarkable data collapse for over twenty experimental conditions, using a constant tortuosity consistent with permeability measurements and the Bruggeman relation. These results establish the accuracy of the Dusty Gas model for multicomponent gas diffusion in porous med...

  5. ENGINEERING MECHANICS SEMINARSENGINEERING MECHANICS SEMINARS THINK COMPOSITE

    E-Print Network [OSTI]

    Ponce, V. Miguel

    ENGINEERING MECHANICS SEMINARSENGINEERING MECHANICS SEMINARS THINK COMPOSITE "THINK outside the box" for more competitive structural COMPOSITES Dr. Melih Papila Visiting Professor, Aero/Astro Department, Stanford University. Adv. Composites and Polymer Processing Lab., Sabanci University, Istanbul. mpapila

  6. Heavy Mobile Equipment Mechanic (One Mechanic Shop)

    Broader source: Energy.gov [DOE]

    The position is a Heavy Mobile Equipment Mechanic (One Mechanic Shop) located in Kent, Washington, and will be responsible for the safe and efficient operation of a field garage performing...

  7. Vapor-phase synthesis of a solid precursor for {alpha}-alumina through a catalytic decomposition of aluminum triisopropoxide

    SciTech Connect (OSTI)

    Nguyen, Tu Quang [Department of Chemical Engineering, Kongju National University, 275 Budae-dong, Cheonan, Chungnam 330-717 (Korea, Republic of)] [Department of Chemical Engineering, Kongju National University, 275 Budae-dong, Cheonan, Chungnam 330-717 (Korea, Republic of); Park, Kyun Young, E-mail: kypark@kongju.ac.kr [Department of Chemical Engineering, Kongju National University, 275 Budae-dong, Cheonan, Chungnam 330-717 (Korea, Republic of); Jung, Kyeong Youl [Department of Chemical Engineering, Kongju National University, 275 Budae-dong, Cheonan, Chungnam 330-717 (Korea, Republic of)] [Department of Chemical Engineering, Kongju National University, 275 Budae-dong, Cheonan, Chungnam 330-717 (Korea, Republic of); Cho, Sung Baek [Korea Institute of Geoscience and Mineral Resources (KIGAM), 92 Gwahang-no, Yuseong-gu 305-350 (Korea, Republic of)] [Korea Institute of Geoscience and Mineral Resources (KIGAM), 92 Gwahang-no, Yuseong-gu 305-350 (Korea, Republic of)

    2011-12-15T23:59:59.000Z

    Highlights: Black-Right-Pointing-Pointer A new solid precursor for {alpha}-alumina was prepared at about 200 Degree-Sign C from aluminum tri-isopropoxide vapor. Black-Right-Pointing-Pointer The obtained precursor was calcined at 1200 Degree-Sign C to form {alpha}-alumina particles, 75 nm in surface area equivalent diameter. Black-Right-Pointing-Pointer The weight loss of the precursor upon calcination was 24%, lower than that of Al(OH){sub 3}, a conventional alumina precursor. -- Abstract: A new solid precursor, hydrous aluminum oxide, for {alpha}-alumina nanoparticles was prepared by thermal decomposition of aluminum triisopropoxide (ATI) vapor in a 500 mL batch reactor at 170-250 Degree-Sign C with HCl as catalyst. The conversion of ATI increased with increasing temperature and catalyst content; it was nearly complete at 250 Degree-Sign C with the catalyst at 10 mol% of the ATI. The obtained precursor particles were amorphous, spherical and loosely agglomerated. The primary particle size is in the range 50-150 nm. The ignition loss of the precursor was 24%, considerably lower than 35% of Al(OH){sub 3}, the popular precursor for alumina particles. Upon calcination of the precursor at 1200 Degree-Sign C in the air with a heating rate of 10 Degree-Sign C/min and a holding time of 2 h, the phase was completely transformed into {alpha}. The spherical particles composing the precursor turned worm-like by the calcination probably due to sintering between neighboring particles. The surface area equivalent diameter of the resulting {alpha}-alumina was 75 nm.

  8. Apparatus and method for maintaining multi-component sample gas constituents in vapor phase during sample extraction and cooling

    DOE Patents [OSTI]

    Felix, Larry Gordon; Farthing, William Earl; Irvin, James Hodges; Snyder, Todd Robert

    2010-05-11T23:59:59.000Z

    A dilution apparatus for diluting a gas sample. The apparatus includes a sample gas conduit having a sample gas inlet end and a diluted sample gas outlet end, and a sample gas flow restricting orifice disposed proximate the sample gas inlet end connected with the sample gas conduit and providing fluid communication between the exterior and the interior of the sample gas conduit. A diluted sample gas conduit is provided within the sample gas conduit having a mixing end with a mixing space inlet opening disposed proximate the sample gas inlet end, thereby forming an annular space between the sample gas conduit and the diluted sample gas conduit. The mixing end of the diluted sample gas conduit is disposed at a distance from the sample gas flow restricting orifice. A dilution gas source connected with the sample gas inlet end of the sample gas conduit is provided for introducing a dilution gas into the annular space, and a filter is provided for filtering the sample gas. The apparatus is particularly suited for diluting heated sample gases containing one or more condensable components.

  9. Chemically sensitive polymer-mediated nanoporous alumina SAW sensors for the detection of vapor-phase analytes

    E-Print Network [OSTI]

    Perez, Gregory Paul

    2005-08-29T23:59:59.000Z

    We have investigated the chemical sensitivity of nanoporous (NP) alumina-coated surface acoustic wave (SAW) devices that have been surface-modified with polymeric mediating films. The research in this dissertation covers the refinement of the NP...

  10. Method and apparatus for maintaining multi-component sample gas constituents in vapor phase during sample extraction and cooling

    DOE Patents [OSTI]

    Farthing, William Earl (Pinson, AL) [Pinson, AL; Felix, Larry Gordon (Pelham, AL) [Pelham, AL; Snyder, Todd Robert (Birmingham, AL) [Birmingham, AL

    2008-02-12T23:59:59.000Z

    An apparatus and method for diluting and cooling that is extracted from high temperature and/or high pressure industrial processes. Through a feedback process, a specialized, CFD-modeled dilution cooler is employed along with real-time estimations of the point at which condensation will occur within the dilution cooler to define a level of dilution and diluted gas temperature that results in a gas that can be conveyed to standard gas analyzers that contains no condensed hydrocarbon compounds or condensed moisture.

  11. Method and apparatus maintaining multi-component sample gas constituents in vapor phase during sample extraction and cooling

    DOE Patents [OSTI]

    Farthing, William Earl (Pinson, AL); Felix, Larry Gordon (Pelham, AL); Snyder, Todd Robert (Birmingham, AL)

    2009-12-15T23:59:59.000Z

    An apparatus and method for diluting and cooling that is extracted from high temperature and/or high pressure industrial processes. Through a feedback process, a specialized, CFD-modeled dilution cooler is employed along with real-time estimations of the point at which condensation will occur within the dilution cooler to define a level of dilution and diluted gas temperature that results in a gas that can be conveyed to standard gas analyzers that contains no condensed hydrocarbon compounds or condensed moisture.

  12. Observation of photoluminescence from Al1 xInxN heteroepitaxial films grown by metalorganic vapor phase epitaxy

    E-Print Network [OSTI]

    Wetzel, Christian M.

    Observation of photoluminescence from Al1 xInxN heteroepitaxial films grown by metalorganic vapor have observed photoluminescence of Al1 xInxN films. The films were grown on GaN by atmospheric pressure-temperature deposited AlN buffer layer. Photoluminescence, absorption, and x-ray diffraction measurements have shown

  13. Organometallic vapor-phase homoepitaxy of gallium arsenide assisted by a downstream hydrogen afterglow plasma in the growth region

    E-Print Network [OSTI]

    Collins, George J.

    of the trimeth- ylgallium (TMGa) for homoepitaxial GaAs. They found in direct comparison of the pure thermal-insulating) substrate is loaded into the depo- sition reactor of Fig. 1 without any chemical degreasing or polishing

  14. Quantitative Infrared Intensity Studies of Vapor-Phase Glyoxal, Methylglyoxal, and 2,3-Butanedione (Diacetyl) with Vibrational Assignments

    SciTech Connect (OSTI)

    Profeta, Luisa T.; Sams, Robert L.; Johnson, Timothy J.; Williams, Stephen D.

    2011-09-08T23:59:59.000Z

    Glyoxal, methylglyoxal and 2,3-butanedione (diacetyl) are all known biomass burning effluents and suspected aerosol precursors. Pressure-broadened quantitative infrared spectra of glyoxal, methylglyoxal and diacetyl vapors covering the 520–6500 cm?1 range are reported at 0.11 cm?1 resolution, each with a composite spectrum derived from a minimum of ten different sample pressures for the compound, representing some of the first quantitative data for these analytes. The ordinate corresponds to a 1 meter optical pathlength and a mixing ratio of 1ppmv at 296 K. Many vibrational assignments for methylglyoxal are reported for the first time, as are some near-IR and far-IR bands of glyoxal and diacetyl. To complete the vibrational assignments, the quantitative far-infrared spectra (25 to 600 cm-1) of all three vapors are also reported, methylglyoxal for the first time. Density functional theory and ab initio MP2 theory are used to help assign vibrational modes. Potential bands useful for atmospheric monitoring are discussed.

  15. Characterizing organometallic-vapor-phase-epitaxy-grown indium gallium nitride islands on gallium nitride for light emitting diode applications.

    E-Print Network [OSTI]

    Anderson, Kathy Perkins Jenkins

    2011-01-01T23:59:59.000Z

    ??The indium-gallium-nitride on gallium-nitride (InGaN/GaN) materials system is a promising candidate for providing a high intensity, high efficiency solution to the yet unsolved problem of… (more)

  16. Formation of etch pits during carbon doping of gallium arsenide with carbon tetrachloride by metalorganic vapor-phase epitaxy

    E-Print Network [OSTI]

    Li, Lian

    Formation of etch pits during carbon doping of gallium arsenide with carbon tetrachloride to examine the effects of carbon tetrachloride concentration and temperature on the morphology of carbon with increasing carbon tetrachloride concentration. Step bunching and pinning was observed at a IV/III ratio

  17. Tribology Letters Vol. 10, No. 3, 2001 179 Activation of the SiC surface for vapor phase lubrication

    E-Print Network [OSTI]

    Gellman, Andrew J.

    above 500 C [2,3,11,12]. Since liquid lubricants cannot withstand such extreme conditions, a number deposition 1. Introduction The lubrication of ceramic surfaces working at extremely high temperatures has lubrication by Fe chemical vapor deposition from Fe(CO)5 Daxing Ren, Dougyong Sung and Andrew J. Gellman

  18. Effects of molecular transport on turbulence-chemistry interactions in a hydrogen-argon-air jet diffusion flame

    SciTech Connect (OSTI)

    Menon, S.; Calhoon, W.H. Jr.; Goldin, G. [Georgia Inst. of Tech., Atlanta, GA (United States). School of Aerospace Engineering; Kerstein, A.R. [Sandia National Labs., Livermore, CA (United States)

    1994-01-01T23:59:59.000Z

    A numerical simulation of entrainment, turbulent advection, molecular import and chemical kinetics in a turbulent diffusion flame is used to investigate effects of molecular transport on turbulence-chemistry interactions. A fun finite-rate chemical mechanism is used to represent the combustion of a hydrogen-argon mixture issuing into air. Results based on incorporation of differential diffusion and variable Lewis number are compared to cases with the former effect, or both-effects, suppressed. Significant impact on radical species production and on NO emission index (based on a reduced mechanism for thermal NO) is found. A reduced mechanism for hydrogen-air combustion, omitting both effects and incorporating other simplifications, performs comparably except that its NO predictions agree well with the case of full chemistry and molecular transport, possibly due to cancellation of errors.

  19. A mechanical model of early salt dome growth

    E-Print Network [OSTI]

    Irwin, Frank Albert

    1988-01-01T23:59:59.000Z

    of Department) December 1988 A Mechanical Analysis of Early Salt Dome Growth. (December 1988) Frank Albert Irwin, B. S. , Texas A&M University Chair of Advisory Committee: Dr. Raymond C. Fletcher A two-layer superposition model, the lower layer representing... of the sediments results in growth rates much higher than those observed. Analysis of the case with a diffusivity of 104m2/Ka agrees with all observa- tions. A range of diffusivities which will produce a realistic salt dome model is then determined. The lower...

  20. Mechanical & Biomedical Engineering

    E-Print Network [OSTI]

    Barrash, Warren

    Mechanical & Biomedical Engineering Department BACHELOR OF SCIENCE IN MECHANICAL ENGINEERING COURSE 105 Mechanical Engineering Graphics 3 CHEM 111L College Chemistry Lab (DLN) 1 ENGL 102 English PHYS 211 Mechanics, Waves & Heat (DLN) 4 UF 100 Intellectual Foundations 3 PHYS 211L Mechanics, Waves

  1. Solar mechanics thermal response capabilities.

    SciTech Connect (OSTI)

    Dobranich, Dean D.

    2009-07-01T23:59:59.000Z

    In many applications, the thermal response of structures exposed to solar heat loads is of interest. Solar mechanics governing equations were developed and integrated with the Calore thermal response code via user subroutines to provide this computational simulation capability. Solar heat loads are estimated based on the latitude and day of the year. Vector algebra is used to determine the solar loading on each face of a finite element model based on its orientation relative to the sun as the earth rotates. Atmospheric attenuation is accounted for as the optical path length varies from sunrise to sunset. Both direct and diffuse components of solar flux are calculated. In addition, shadowing of structures by other structures can be accounted for. User subroutines were also developed to provide convective and radiative boundary conditions for the diurnal variations in air temperature and effective sky temperature. These temperature boundary conditions are based on available local weather data and depend on latitude and day of the year, consistent with the solar mechanics formulation. These user subroutines, coupled with the Calore three-dimensional thermal response code, provide a complete package for addressing complex thermal problems involving solar heating. The governing equations are documented in sufficient detail to facilitate implementation into other heat transfer codes. Suggestions for improvements to the approach are offered.

  2. Mechanical Engineering Graduate Student

    E-Print Network [OSTI]

    Wisconsin at Madison, University of

    ......................................................................................9 Engineering Career Services ................................................................9 McMechanical Engineering Graduate Student Handbook January 2014 Department of Mechanical Engineering University of Wisconsin-Madison #12;Mechanical Engineering Web Page: http://www.engr.wisc.edu/me Graduate

  3. Mechanical & Industrial Engineering

    E-Print Network [OSTI]

    Mountziaris, T. J.

    Mechanical & Industrial Engineering 1 Welcome MIE Industrial Advisory Board October 15, 2010 #12;Mechanical & Industrial Engineering 2 MIE Dorothy Adams Undergraduate/Graduate Secretary David Schmidt Associate Professor & Graduate Program Director #12;Mechanical & Industrial Engineering 3 MIE James Rinderle

  4. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    and the Department of Mechanical Engineering Tufts University Retooling Our Energy Ecosystem: challengesMechanical engineering Department Seminar Robert J. Hannemann The Gordon Institute and Chair of the Tufts Department of Mechanical Engineering. His technical and academic interests

  5. MECHANICAL ENGINEERING UNDERGRADUATE MAJOR

    E-Print Network [OSTI]

    HANDBOOK FOR MECHANICAL ENGINEERING UNDERGRADUATE MAJOR Old Dominion University Department of Mechanical Engineering Batten College of Engineering and Technology Norfolk, Virginia 23529-0247 #12;TABLE OF CONTENTS MECHANICAL ENGINEERING HANDBOOK

  6. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    Mechanical engineering Department Seminar Katia Bertoldi Harvard University Soft materials in response to diverse stimuli. While the mechanical attributes - such as energy absorption, stiffness and switchable functionalities. Katia Bertoldi is an Assistant Professor of Applied Mechanics at Harvard

  7. Diffusion of Iodine and Rhenium in Category 3 Waste Encasement Concrete and Soil Fill Material

    SciTech Connect (OSTI)

    Wellman, Dawn M.; Mattigod, Shas V.; Whyatt, Greg A.; Powers, Laura; Parker, Kent E.; Wood, Marcus I.

    2006-12-15T23:59:59.000Z

    Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e. sorption or precipitation). This understanding will enable accurate prediction of radionuclide fate when the waste forms come in contact with groundwater. A set of diffusion experiments using carbonated and non-carbonated concrete-soil half cells was conducted under unsaturated conditions (4% and 7% by wt moisture content). Spiked concrete half-cell specimens were prepared with and without colloidal metallic iron addition and were carbonated using supercritical carbon dioxide. Spikes of I and Re were added to achieve measurable diffusion profile in the soil part of the half-cell. In addition, properties of concrete materials likely to influence radionuclide migration such as carbonation were evaluated in an effort to correlate these properties with the release of iodine and rhenium.

  8. L\\'evy Fluctuations and Tracer Diffusion in Dilute Suspensions of Algae and Bacteria

    E-Print Network [OSTI]

    Zaid, Irwin M; Yeomans, Julia M

    2010-01-01T23:59:59.000Z

    Swimming microorganisms rely on effective mixing strategies to achieve efficient nutrient influx. Recent experiments, probing the mixing capability of unicellular biflagellates, revealed that passive tracer particles exhibit anomalous non-Gaussian diffusion when immersed in a dilute suspension of self-motile Chlamydomonas reinhardtii algae. Qualitatively, this observation can be explained by the fact that the algae induce a fluid flow that may occasionally accelerate the colloidal tracers to relatively large velocities. A satisfactory quantitative theory of enhanced mixing in dilute active suspensions, however, is lacking at present. In particular, it is unclear how non-Gaussian signatures in the tracers' position distribution are linked to the self-propulsion mechanism of a microorganism. Here, we develop a systematic theoretical description of anomalous tracer diffusion in active suspensions, based on a simplified tracer-swimmer interaction model that captures the typical distance scaling of a microswimmer'...

  9. On-line vibration and analysis system at the Paducah Gaseous Diffusion Plant

    SciTech Connect (OSTI)

    Herricks, D.M.; Strunk, W.D.

    1988-02-01T23:59:59.000Z

    The enrichment facility in Paducah, KY uses a unique hard-wired vibration monitoring and analysis system for gaseous diffusion equipment. The axial flow and centrifugal flow compressors used in uranium enrichment range in size from 6 feet in diameter to less than one foot in diameter. These compressors must operate smoothly and safely, without breech of containment, since the working fluid of gaseous diffusion is gaseous UF/sub 6/. The condition of 1925 compressors is monitored by use of the 2500 point vibration analysis system. Since the failure mechanisms of the compressors are well known and documented, only one accelerometer per machine is needed for most machines. The system is completely automated and can generate spectra or broadband levels in either acceleration or velocity units. Levels are stored for historical review. The analyst can, via a custom telecommunications link, view and analyze data from all monitored points with an office PC. 4 figs.

  10. Flux-Limited Diffusion Approximation Models of Giant Planet Formation by Disk Instability

    E-Print Network [OSTI]

    Boss, Alan P

    2008-01-01T23:59:59.000Z

    Both core accretion and disk instability appear to be required as formation mechanisms in order to explain the entire range of giant planets found in extrasolar planetary systems. Disk instability is based on the formation of clumps in a marginally-gravitationally unstable protoplanetary disk. These clumps can only be expected to contract and survive to become protoplanets if they are able to lose thermal energy through a combination of convection and radiative cooling. Here we present several new three dimensional, radiative hydrodynamics models of self-gravitating protoplanetary disks, where radiative transfer is handled in the flux-limited diffusion approximation. We show that while the flux-limited models lead to higher midplane temperatures than in a diffusion approximation model without the flux-limiter, the difference in temperatures does not appear to be sufficiently high to have any significant effect on the formation of self-gravitating clumps. Self-gravitating clumps form rapidly in the models both...

  11. Diffusion injected multi-quantum well light-emitting diode structure

    SciTech Connect (OSTI)

    Riuttanen, L., E-mail: lauri.riuttanen@aalto.fi; Nykänen, H.; Svensk, O.; Suihkonen, S.; Sopanen, M. [Department of Micro- and Nanosciences, Aalto University, P.O. Box 13500, FI-00076 Aalto (Finland); Kivisaari, P.; Oksanen, J.; Tulkki, J. [Department of Biomedical Engineering and Computational Science, Aalto University, P.O. Box 12200, FI-00076 Aalto (Finland)

    2014-02-24T23:59:59.000Z

    The attention towards light-emitting diode (LED) structures based on nanowires, surface plasmon coupled LEDs, and large-area high-power LEDs has been increasing for their potential in increasing the optical output power and efficiency of LEDs. In this work we demonstrate an alternative way to inject charge carriers into the active region of an LED, which is based on completely different current transport mechanism compared to conventional current injection approaches. The demonstrated structure is expected to help overcoming some of the challenges related to current injection with conventional structures. A functioning III-nitride diffusion injected light-emitting diode structure, in which the light-emitting active region is located outside the pn-junction, is realized and characterized. In this device design, the charge carriers are injected into the active region by bipolar diffusion, which could also be utilized to excite otherwise challenging to realize light-emitting structures.

  12. Diffusion Dominant Solute Transport Modelling In Deep Repository Under The Effect of Emplacement Media Degradation - 13285

    SciTech Connect (OSTI)

    Kwong, S. [National Nuclear Laboratory (United Kingdom)] [National Nuclear Laboratory (United Kingdom); Jivkov, A.P. [Research Centre for Radwaste and Decommissioning and Modelling and Simulation Centre, University of Manchester (United Kingdom)] [Research Centre for Radwaste and Decommissioning and Modelling and Simulation Centre, University of Manchester (United Kingdom)

    2013-07-01T23:59:59.000Z

    Deep geologic disposal of high activity and long-lived radioactive waste is being actively considered and pursued in many countries, where low permeability geological formations are used to provide long term waste contaminant with minimum impact to the environment and risk to the biosphere. A multi-barrier approach that makes use of both engineered and natural barriers (i.e. geological formations) is often used to further enhance the containment performance of the repository. As the deep repository system subjects to a variety of thermo-hydro-chemo-mechanical (THCM) effects over its long 'operational' lifespan (e.g. 0.1 to 1.0 million years, the integrity of the barrier system will decrease over time (e.g. fracturing in rock or clay)). This is broadly referred as media degradation in the present study. This modelling study examines the effects of media degradation on diffusion dominant solute transport in fractured media that are typical of deep geological environment. In particular, reactive solute transport through fractured media is studied using a 2-D model, that considers advection and diffusion, to explore the coupled effects of kinetic and equilibrium chemical processes, while the effects of degradation is studied using a pore network model that considers the media diffusivity and network changes. Model results are presented to demonstrate the use of a 3D pore-network model, using a novel architecture, to calculate macroscopic properties of the medium such as diffusivity, subject to pore space changes as the media degrade. Results from a reactive transport model of a representative geological waste disposal package are also presented to demonstrate the effect of media property change on the solute migration behaviour, illustrating the complex interplay between kinetic biogeochemical processes and diffusion dominant transport. The initial modelling results demonstrate the feasibility of a coupled modelling approach (using pore-network model and reactive transport model) to examine the long term behaviour of deep geological repositories with media property change under complex geochemical conditions. (authors)

  13. Meyer-Neldel rule for Cu (I) diffusion in In{sub 2}S{sub 3} layers

    SciTech Connect (OSTI)

    Juma, Albert, E-mail: albert.juma@helmholtz-berlin.de; Dittrich, Thomas [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Wafula, Henry [Masinde Muliro University of Science and Technology, P.O. Box 190-50100, Kakamega (Kenya); Wendler, Elke [Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena (Germany)

    2014-02-07T23:59:59.000Z

    The nature of barriers for atomic transport in In{sub 2}S{sub 3} layers has been varied by addition of chlorine. Diffusion of Cu(I) from a removable CuSCN source was used to probe the variation of the barriers. The Meyer-Neldel (compensation) rule was observed with a Meyer-Neldel energy (E{sub MN}) and a proportionality prefactor (D{sub 00}) amounting to 40?meV and 5?×?10{sup ?14} cm{sup 2}/s, respectively. D{sub 00} shows that the elementary excitation step is independent of the specific mechanism and nature of the barrier including different densities of Cl in In{sub 2}S{sub 3}. The value of E{sub MN} implies that coupling of the diffusing species to an optical-phonon bath is the source of the multiple excitations supplying the energy to overcome the diffusion barriers.

  14. Causal Baryon Diffusion and Colored Noise

    E-Print Network [OSTI]

    J. I. Kapusta; C. Young

    2014-04-18T23:59:59.000Z

    We construct a model of baryon diffusion which has the desired properties of causality and analyticity. The model also has the desired property of colored noise, meaning that the noise correlation function is not a Dirac delta function in space and time; rather, it depends on multiple time and length constants. The model can readily be incorporated in 3+1 dimensional second order viscous hydro-dynamical models of heavy ion collisions, which is particularly important at beam energies where the baryon density is large.

  15. Band Formation during Gaseous Diffusion in Aerogels

    E-Print Network [OSTI]

    M. A. Einarsrud; F. A. Maao; A. Hansen; M. Kirkedelen; J. Samseth

    1997-06-18T23:59:59.000Z

    We study experimentally how gaseous HCl and NH_3 diffuse from opposite sides of and react in silica aerogel rods with porosity of 92 % and average pore size of about 50 nm. The reaction leads to solid NH_4Cl, which is deposited in thin sheet-like structures. We present a numerical study of the phenomenon. Due to the difference in boundary conditions between this system and those usually studied, we find the sheet-like structures in the aerogel to differ significantly from older studies. The influence of random nucleation centers and inhomogeneities in the aerogel is studied numerically.

  16. Diffusion for an ensemble of Hamiltonians

    E-Print Network [OSTI]

    Or Alus; Shmuel Fishman

    2014-09-17T23:59:59.000Z

    Two ensembles of standard maps are studied analytically and numerically. In particular the diffusion coefficient is calculated. For one type of ensemble the chaotic parameter is chosen at random from a Gaussian distribution and is then kept fixed, while for the other type it varies from step to step. The effect of averaging out the details is evaluated and in particular it is found to be much more effective in the process of the second type. The work may shed light on the possible properties of different ensembles of mixed systems.

  17. Diffuse Irradiance Study Planned for October

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation Proposed Newcatalyst phasesData FilesShape,Physics DiagnosticsMicrochips. |Energy3 Diffuse

  18. ARM - Field Campaign - Diffuse Shortwave IOP

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered‰PNGExperience4AJ01)3,Cloud OD SensorgovCampaignsComplex LayeredgovCampaignsDiffuse

  19. Comparison of Diffuse Shortwave Irradiance Measurements

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation Proposed New SubstationCleanCommunity Involvement andMISR, and MODIS Comparison ofDiffuse

  20. Carbon Diffusion Across Dissimilar Steel Welds

    E-Print Network [OSTI]

    Race, Julia Margaret

    1992-12-08T23:59:59.000Z

    of recrystallised ferrite. The major consequence of carbon diffusion is a loss of strength in the carbon depleted region and an increase in hardness in the carburised region. These zones are immediately adjacent to one another and provide a significant change... , tungsten and niobium, a sequence of alloy carbides may be formed, giving rise to the more complex M23C6 and M6C carbides at higher tempering temperatures. In this notation "M" indicates a mixture of metal atoms. Nutting (1969) summarises the sequence...

  1. Low-temperature lithium diffusion in simulated high-level boroaluminosilicate nuclear waste glasses

    SciTech Connect (OSTI)

    Neeway, James J.; Kerisit, Sebastien N.; Gin, Stephane; Wang, Zhaoying; Zhu, Zihua; Ryan, Joseph V.

    2014-12-01T23:59:59.000Z

    Ion exchange is recognized as an integral, if underrepresented, mechanism influencing glass corrosion. However, due to the formation of various alteration layers in the presence of water, it is difficult to conclusively deconvolute the mechanisms of ion exchange from other processes occurring simultaneously during corrosion. In this work, an operationally inert non-aqueous solution was used as an alkali source material to isolate ion exchange and study the solid-state diffusion of lithium. Specifically, the experiments involved contacting glass coupons relevant to the immobilization of high-level nuclear waste, SON68 and CJ-6, which contained Li in natural isotope abundance, with a non-aqueous solution of 6LiCl dissolved in dimethyl sulfoxide at 90 °C for various time periods. The depth profiles of major elements in the glass coupons were measured using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Lithium interdiffusion coefficients, DLi, were then calculated based on the measured depth profiles. The results indicate that the penetration of 6Li is rapid in both glasses with the simplified CJ-6 glass (D6Li ? 4.0-8.0 × 10-21 m2/s) exhibiting faster exchange than the more complex SON68 glass (DLi ? 2.0-4.0 × 10-21 m2/s). Additionally, sodium ions present in the glass were observed to participate in ion exchange reactions; however, different diffusion coefficients were necessary to fit the diffusion profiles of the two alkali ions. Implications of the diffusion coefficients obtained in the absence of alteration layers to the long-term performance of nuclear waste glasses in a geological repository system are also discussed.

  2. On Similarities between Biological and Social Evolutionary Mechanisms: Mathematical Modeling

    E-Print Network [OSTI]

    Grinin, Leonid; Markov, Alexander; Korotayev, Andrey

    2013-01-01T23:59:59.000Z

    of widely diffused social innovation that enhances theof widely diffused social innovation that enhances the

  3. Chemical oxygen diffusion coefficient measurement by conductivity relaxation--correlation between tracer diffusion

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Chemical oxygen diffusion coefficient measurement by conductivity relaxation--correlation between J. P., Grenier J. C., Loup J. P. ABSTRACT Chemical oxygen diusion coecient ¯(D)was measured the oxygen partial pressure in the surrounding atmosphere of the sample. The consequent evolution

  4. Low cost fuel cell diffusion layer configured for optimized anode water management

    DOE Patents [OSTI]

    Owejan, Jon P; Nicotera, Paul D; Mench, Matthew M; Evans, Robert E

    2013-08-27T23:59:59.000Z

    A fuel cell comprises a cathode gas diffusion layer, a cathode catalyst layer, an anode gas diffusion layer, an anode catalyst layer and an electrolyte. The diffusion resistance of the anode gas diffusion layer when operated with anode fuel is higher than the diffusion resistance of the cathode gas diffusion layer. The anode gas diffusion layer may comprise filler particles having in-plane platelet geometries and be made of lower cost materials and manufacturing processes than currently available commercial carbon fiber substrates. The diffusion resistance difference between the anode gas diffusion layer and the cathode gas diffusion layer may allow for passive water balance control.

  5. Overview of SIMS-Based Experimental Studies of Tracer Diffusion in Solids and Application to Mg Self-Diffusion

    SciTech Connect (OSTI)

    Kulkarni, Nagraj S [ORNL; Warmack, Robert J Bruce [ORNL; Radhakrishnan, Balasubramaniam [ORNL; HunterJr., Jerry [Virginia Polytechnic Institute and State University; Sohn, Yong Ho [University of Central Florida; Coffey, Kevin [University of Central Florida; Murch, Prof. Graeme [University of Newcastle, NSW, Australia; Belova, Irina [University of Newcastle, NSW, Australia

    2014-01-01T23:59:59.000Z

    Tracer diffusivities provide the most fundamental information on diffusion in materials and are the foundation of robust diffusion databases. Compared to traditional radiotracer techniques that utilize radioactive isotopes, the secondary ion mass spectrometry (SIMS) based thin-film technique for tracer diffusion is based on the use of enriched stable isotopes that can be accurately profiled using SIMS. Experimental procedures & techniques that are utilized for the measurement of tracer diffusion coefficients are presented for pure magnesium, which presents some unique challenges due to the ease of oxidation. The development of a modified Shewmon-Rhines diffusion capsule for annealing Mg and an ultra-high vacuum (UHV) system for sputter deposition of Mg isotopes are discussed. Optimized conditions for accurate SIMS depth profiling in polycrystalline Mg are provided. An automated procedure for the correction of heat-up and cool-down times during tracer diffusion annealing is discussed. The non-linear fitting of a SIMS depth profile data using the thin film Gaussian solution to obtain the tracer diffusivity along with the background tracer concentration and tracer film thickness is discussed. An Arrhenius fit of the Mg self-diffusion data obtained using the low-temperature SIMS measurements from this study and the high-temperature radiotracer measurements of Shewmon and Rhines (1954) was found to be a good representation of both types of diffusion data that cover a broad range of temperatures between 250 - 627 C (523 900 K).

  6. Reaction and diffusion in turbulent combustion

    SciTech Connect (OSTI)

    Pope, S.B. [Mechanical and Aerospace Engineering, Ithaca, NY (United States)

    1993-12-01T23:59:59.000Z

    The motivation for this project is the need to obtain a better quantitative understanding of the technologically-important phenomenon of turbulent combustion. In nearly all applications in which fuel is burned-for example, fossil-fuel power plants, furnaces, gas-turbines and internal-combustion engines-the combustion takes place in a turbulent flow. Designers continually demand more quantitative information about this phenomenon-in the form of turbulent combustion models-so that they can design equipment with increased efficiency and decreased environmental impact. For some time the PI has been developing a class of turbulent combustion models known as PDF methods. These methods have the important virtue that both convection and reaction can be treated without turbulence-modelling assumptions. However, a mixing model is required to account for the effects of molecular diffusion. Currently, the available mixing models are known to have some significant defects. The major motivation of the project is to seek a better understanding of molecular diffusion in turbulent reactive flows, and hence to develop a better mixing model.

  7. Distributed Wind Diffusion Model Overview (Presentation)

    SciTech Connect (OSTI)

    Preus, R.; Drury, E.; Sigrin, B.; Gleason, M.

    2014-07-01T23:59:59.000Z

    Distributed wind market demand is driven by current and future wind price and performance, along with several non-price market factors like financing terms, retail electricity rates and rate structures, future wind incentives, and others. We developed a new distributed wind technology diffusion model for the contiguous United States that combines hourly wind speed data at 200m resolution with high resolution electricity load data for various consumer segments (e.g., residential, commercial, industrial), electricity rates and rate structures for utility service territories, incentive data, and high resolution tree cover. The model first calculates the economics of distributed wind at high spatial resolution for each market segment, and then uses a Bass diffusion framework to estimate the evolution of market demand over time. The model provides a fundamental new tool for characterizing how distributed wind market potential could be impacted by a range of future conditions, such as electricity price escalations, improvements in wind generator performance and installed cost, and new financing structures. This paper describes model methodology and presents sample results for distributed wind market potential in the contiguous U.S. through 2050.

  8. Diffusion in biofilms respiring on electrodes

    SciTech Connect (OSTI)

    Renslow, Ryan S.; Babauta, Jerome T.; Majors, Paul D.; Beyenal, Haluk

    2013-02-15T23:59:59.000Z

    The goal of this study was to measure spatially and temporally resolved effective diffusion coefficients (De) in biofilms respiring on electrodes. Two model electrochemically active biofilms, Geobacter sulfurreducens PCA and Shewanella oneidensis MR-1, were investigated. A novel nuclear magnetic resonance microimaging perfusion probe capable of simultaneous electrochemical and pulsed-field gradient nuclear magnetic resonance (PFG-NMR) techniques was used. PFG-NMR allowed for noninvasive, nondestructive, high spatial resolution in situ De measurements in living biofilms respiring on electrodes. The electrodes were polarized so that they would act as the sole terminal electron acceptor for microbial metabolism. We present our results as both two-dimensional De heat maps and surface-averaged relative effective diffusion coefficient (Drs) depth profiles. We found that (1) Drs decreases with depth in G. sulfurreducens biofilms, following a sigmoid shape; (2) Drs at a given location decreases with G. sulfurreducens biofilm age; (3) average De and Drs profiles in G. sulfurreducens biofilms are lower than those in S. oneidensis biofilms—the G. sulfurreducens biofilms studied here were on average 10 times denser than the S. oneidensis biofilms; and (4) halting the respiration of a G. sulfurreducens biofilm decreases the De values. Density, reflected by De, plays a major role in the extracellular electron transfer strategies of electrochemically active biofilms.

  9. Narrow groove welding gas diffuser assembly and welding torch

    DOE Patents [OSTI]

    Rooney, Stephen J. (East Berne, NY)

    2001-01-01T23:59:59.000Z

    A diffuser assembly is provided for narrow groove welding using an automatic gas tungsten arc welding torch. The diffuser assembly includes a manifold adapted for adjustable mounting on the welding torch which is received in a central opening in the manifold. Laterally extending manifold sections communicate with a shield gas inlet such that shield gas supplied to the inlet passes to gas passages of the manifold sections. First and second tapered diffusers are respectively connected to the manifold sections in fluid communication with the gas passages thereof. The diffusers extend downwardly along the torch electrode on opposite sides thereof so as to release shield gas along the length of the electrode and at the distal tip of the electrode. The diffusers are of a transverse width which is on the order of the thickness of the electrode so that the diffusers can, in use, be inserted into a narrow welding groove before and after the electrode in the direction of the weld operation.

  10. Non-Fickian ionic diffusion across high-concentration gradients

    SciTech Connect (OSTI)

    Carey, A.E.; Wheatcraft, S.W. [Univ. of Nevada, Reno, NV (United States)] [Univ. of Nevada, Reno, NV (United States); Glass, R.J. [Sandia National Laboratory, Albuquerque, NM (United States)] [and others] [Sandia National Laboratory, Albuquerque, NM (United States); and others

    1995-09-01T23:59:59.000Z

    A non-Fickian physico-chemical model for electrolyte transport in high-ionic strength systems is developed and tested with laboratory experiments with copper sulfate as an example electrolyte. The new model is based on irreversible thermodynamics and uses measured mutual diffusion coefficients, varying with concentration. Compared to a traditional Fickian model, the new model predicts less diffusion and asymmetric diffusion profiles. Laboratory experiments show diffusion rates even smaller than those predicted by our non-Fickian model, suggesting that there are additional, unaccounted for processes retarding diffusion. Ionic diffusion rates maybe a limiting factor in transporting salts whose effect on fluid density will in turn significantly affect the flow regime. These findings have important implications for understanding and predicting solute transport in geologic settings where dense, saline solutions occur. 30 refs., 5 figs.

  11. Mechanical & Industrial Engineering

    E-Print Network [OSTI]

    Mountziaris, T. J.

    Mechanical & Industrial Engineering 1 Welcome MIE Industrial Advisory Board May 5th, 2011 #12;Mechanical & Industrial Engineering 2 IAB 2010-2011 · David K. Anderson ­ Alden Research Laboratory, Inc went on for three weeks Mechanical & Industrial Engineering 6 #12;Reza Shahbazian Yassar Mechanical

  12. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    Lin, Xi

    Mechanical engineering Department Seminar Ju Li Professor MIT Electrochemical-mechanical actions computational and experimental research on mechanical properties of materials, and energy storage and conversion Refreshments served at 10:45 AM The creation of a nanoscale electrochemical and mechanical testing platform

  13. Mechanical Engineering Undergraduate

    E-Print Network [OSTI]

    Ghosh, Somnath

    Mechanical Engineering Department Undergraduate Advising Manual for Bachelor of Science Degrees in Mechanical Engineering and Engineering Mechanics 2011-2012 - Updated April 15, 2012 #12;Johns Hopkins University ­ Department of Mechanical Engineering 2011-2012 Undergraduate Student Advising Manual Page 2

  14. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    Mechanical engineering Department Seminar James Bird Department of Mechanical Engineering Boston ­ are discussed. James Bird is an Assistant Professor in the Mechanical Engineering Department at Boston completed post-doctoral research at MIT. His research interests include experimental fluid mechanics

  15. Mechanical Engineering Undergraduate

    E-Print Network [OSTI]

    Ghosh, Somnath

    Mechanical Engineering Department Undergraduate Advising Manual for Bachelor of Science Degrees in Mechanical Engineering and Engineering Mechanics 2012-2013 - Updated July 14, 2013 #12;Johns Hopkins University ­ Department of Mechanical Engineering 2012-2013 Undergraduate Student Advising Manual Page 2

  16. Mechanical Engineering & Thermal Group

    E-Print Network [OSTI]

    Mojzsis, Stephen J.

    Mechanical Engineering & Thermal Group The Mechanical Engineering (ME) & Thermal Group at LASP has, and ground- based mechanical systems. Instrument Design Building on decades of design experience that has evolved with the complexity of instrument design demands, LASP mechanical engineers develop advanced

  17. Combined Quantum Mechanical and Molecular Mechanics Studies of...

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

    Mechanical and Molecular Mechanics Studies of the Electron-Transfer Reactions Involving Carbon Tetrachloride in Combined Quantum Mechanical and Molecular Mechanics Studies of the...

  18. Lattice Boltzmann computations for reaction-diffusion equations

    SciTech Connect (OSTI)

    Ponce Dawson, S.; Chen, S.; Doolen, G.D. (Center for Nonlinear Studies and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States))

    1993-01-15T23:59:59.000Z

    A lattice Boltzmann model for reaction-diffusion systems is developed. The method provides an efficient computational scheme for simulating a variety of problems described by the reaction-diffusion equations. Diffusion phenomena, the decay to a limit cycle, and the formation of Turing patterns are studied. The results of lattice Boltzmann calculations are compared with the lattice gas method and with theoretical predictions, showing quantitative agreement. The model is extended to include velocity convection in chemically reacting fluid flows.

  19. Methyl viologen mediated oxidation-reduction across dihexadecylphosphate vesicles involves transmembrane diffusion

    SciTech Connect (OSTI)

    Patterson, B.C.; Thompson, D.H.; Hurst, J.K.

    1988-05-25T23:59:59.000Z

    Numerous reports have appeared describing oxidation-reduction across bilayer membranes. Mechanisms proposed for specific systems include the following: (i) electron tunneling across the hydrocarbon barrier between interfacially bound redox partners, (ii) molecular diffusion of bound redox components across the barrier, and (iii) formation of barrier-penetrating aggregates, or electron-conducting channels, across the bilayer. Nonetheless, the actual reaction mechanisms remain obscure due to the general unavailability of transverse diffusion rates, possible loss of compartmentation of reactants, particularly in photochemical systems, and the ambiguities inherent in deducing reaction mechanisms from rate data, which form the primary evidence in most systems studied. The reactions of dihexadecylphosphate (DHP) vesicle-bound methyl viologen (MV/sup 2 +/) describes in this report are unique in allowing deduction of molecular details of a transmembrane redox event from the product composition and microphase distribution. Specifically, they have found that MV/sup 2 +/ bound at the outer vesicle interface mediates reduction of inner-localized MV/sup 2 +/ by dithionite ion in bulk solution in a manner that requires comigration of MV/sup +/ with the electron transferred across the membrane barrier.

  20. 18.366 Random Walks and Diffusion, Spring 2005

    E-Print Network [OSTI]

    Bazant, Martin Z.

    Discrete and continuum modeling of diffusion processes in physics, chemistry, and economics. Topics include central limit theorems, continuous-time random walks, Levy flights, correlations, extreme events, mixing, ...

  1. Optical waveguides in SBN by zinc vapor diffusion

    E-Print Network [OSTI]

    Quinn, Jeffrey Dale

    1991-01-01T23:59:59.000Z

    at 600'C for a 12. 5 i1m Wide 1000'C Zinc Vapor Diffused SBN:60 Waveguide Measured at X = 0. 81 pm. IV. SBN:60 Amplitude Modulator Results . . . . . V. SBN:60 Mach-Zehnder Interferometer Results. . . . VI. Voltage-Length Product Comparison...: (a) extraordinary (TM), (b) 1. 5 x ordinary (TE). 12. Surface damage on SBN:60 diffused at 1000'C with an SiOz diffusion mask. 13. Zinc in-diffusion in SBN:60 25 . . . . . 26 . . . . . 27 . . . . . 28 29 14. Barium out-diffuison in SBN:60...

  2. Diffusion coefficient of three-dimensional Yukawa liquids

    SciTech Connect (OSTI)

    Dzhumagulova, K. N.; Ramazanov, T. S.; Masheeva, R. U. [IETP, Al Farabi Kazakh National University, 71, al Farabi ave., Almaty 050040 (Kazakhstan)] [IETP, Al Farabi Kazakh National University, 71, al Farabi ave., Almaty 050040 (Kazakhstan)

    2013-11-15T23:59:59.000Z

    The purpose of this work is an investigation of the diffusion coefficient of the dust component in complex plasma. The computer simulation of the Yukawa liquids was made on the basis of the Langevin equation, which takes into account the influence of buffer plasma on the dust particles dynamics. The Green–Kubo relation was used to calculate the diffusion coefficient. Calculations of the diffusion coefficient for a wide range of the system parameters were performed. Using obtained numerical data, we constructed the interpolation formula for the diffusion coefficient. We also show that the interpolation formula correctly describes experimental data obtained under microgravity conditions.

  3. Probabilistic Bisimulations of Switching and Resetting Diffusions Alessandro Abate

    E-Print Network [OSTI]

    Abate, Alessandro

    Probabilistic Bisimulations of Switching and Resetting Diffusions Alessandro Abate Delft Center for Systems and Control, TU Delft, The Netherlands a.abate@tudelft.nl Abstract-- This contribution presents

  4. Using Rare Gas Permeation to Probe Methanol Diffusion near the...

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

    at temperatures just above the glass transition. The diffusivity near the glass transition is characterized by an activation energy and prefactor that are seven and 1030...

  5. Uranium and Strontium Batch Sorption and Diffusion Kinetics into...

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

    Uranium and Strontium Batch Sorption and Diffusion Kinetics into Mesoporous Silica Friday, February 27, 2015 Figure 1 Figure 1. Transmission electron microscopy images of (A)...

  6. Optical processing furnace with quartz muffle and diffuser plate

    DOE Patents [OSTI]

    Sopori, Bhushan L. (Denver, CO)

    1995-01-01T23:59:59.000Z

    An optical furnace for annealing a process wafer comprising a source of optical energy, a quartz muffle having a door to hold the wafer for processing, and a quartz diffuser plate to diffuse the light impinging on the quartz muffle; a feedback system with a light sensor located in the door or wall of the muffle is also provided for controlling the source of optical energy. The quartz for the diffuser plate is surface etched (to give the quartz diffusive qualities) in the furnace during a high intensity burn-in process.

  7. aerospace knowledge diffusion: Topics by E-print Network

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

    to codify: Implications for the knowledge - based economy" Prometheus 19 Richards, Debbie 15 Inverse diffusion from knowledge of power densities Guillaume Bal Mathematics...

  8. adrenal diffuse large: Topics by E-print Network

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

    diffusion is the effect of geometry, including the localization of aftershocks on a fractal fault network and the impact of extended rupture lengths which control the typical...

  9. Orientation Visit to the Portsmouth Gaseous Diffusion Plant

    Office of Environmental Management (EM)

    Analysis (DSA) and Technical Safety Requirements (TSR) for Portsmouth Gaseous Diffusion Plant Category 2 Non-leased Facilities: X-345 Special Nuclear Material Storage Facility;...

  10. Falsification of dark energy by fluid mechanics

    E-Print Network [OSTI]

    Gibson, Carl H

    2012-01-01T23:59:59.000Z

    The 2011 Nobel Prize in Physics was awarded for the discovery of accelerating supernovae dimness, suggesting a remarkable change in the expansion rate of the Universe from a decrease since the big bang to an increase, driven by anti-gravity forces of a mysterious dark energy material comprising 70% of the Universe mass-energy. Fluid mechanical considerations falsify both the accelerating expansion and dark energy concepts. Kinematic viscosity is neglected in current standard models of self-gravitational structure formation, which rely on cold dark matter CDM condensations and clusterings that are also falsified by fluid mechanics. Weakly collisional CDM particles do not condense but diffuse away. Photon viscosity predicts superclustervoid fragmentation early in the plasma epoch and protogalaxies at the end. At the plasma-gas transition, the plasma fragments into Earth-mass gas planets in trillion planet clumps (proto-globular-star-cluster PGCs). The hydrogen planets freeze to form the dark matter of galaxies ...

  11. Li ion diffusion mechanism in the crystalline electrolyte -Li3PO4

    E-Print Network [OSTI]

    Holzwarth, Natalie

    battery3 Solid state electrolyte could be made very thin to overcome to the low ion- conductivity et al., Solid State Ionics 53-56, 647 (1992). 3. http://www.ms.ornl.gov/researchgroups/Functional/BatteryV)material kTEA e T K T / )( - = 1. B. Wang et al., J. of Solid State Chemistry 115, 313 (1995). 2. J. B. Bates

  12. Signal generation mechanisms, intracavity-gas thermal-diffusivity temperature dependence, and absolute infrared emissivity measurements

    E-Print Network [OSTI]

    Mandelis, Andreas

    , Canada Received 22 September 1997; accepted for publication 8 October 1997 The operating thermal power dominance of thermal-wave radiation power transfer in the phase channel of the thermal-wave signal at large produces an ac electrical signal proportional to the energy of the standing thermal-wave pattern

  13. Compaction Effects on Uniformity, Moisture Diffusion, and Mechanical Properties of Asphalt Pavements

    E-Print Network [OSTI]

    Kassem, Emad Abdel-Rahman Ahmed

    2011-08-08T23:59:59.000Z

    Field compaction of asphalt mixtures is an important process that influences performance of asphalt pavements; however there is very little effort devoted to evaluate the influence of compaction on the uniformity and properties of asphalt mixtures...

  14. Sandia National Laboratories: Mechanical Testing

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

    EnergyNuclear Energy Systems Laboratory (NESL) Brayton LabMechanical Testing Mechanical Testing Mechanical Testing Overview Mechanical 1-2 (2008). Standard Test Methods for...

  15. When Smoothening Makes It Rough: Unhindered Step-Edge Diffusion and the Meandering Instability on Metal Surfaces

    SciTech Connect (OSTI)

    Nita, F. [LASMEA, UMR 6602 CNRS, Universite Blaise Pascal-Clermont 2, F-63177 Aubiere Cedex (France); Institute of Physical Chemistry 'IG Murgulescu' of Romanian Academy, Splaiul Independentei 202, Bucharest (Romania); Pimpinelli, A. [LASMEA, UMR 6602 CNRS, Universite Blaise Pascal-Clermont 2, F-63177 Aubiere Cedex (France)

    2005-09-02T23:59:59.000Z

    The precise microscopic origin of step meandering is not known in many real situations. A detailed study of this instability has been made for copper, and none of the microscopic mechanisms proposed until now is able to describe all of the observed characteristic features of the instability, in particular, its dependence on the crystallographic orientations of steps. We propose a novel scenario, and using kinetic Monte Carlo simulations we show that essentially all features of step meandering of copper can be explained, if atoms diffuse along step edges and freely turn around the kinks they encounter along the ledge. Then, in a rather counterintuitive way, step meandering appears due to the very mechanism -step-edge diffusion - that may be expected to oppose it.

  16. Mapping the geographical diffusion of new words

    E-Print Network [OSTI]

    Eisenstein, Jacob; Smith, Noah A; Xing, Eric P

    2012-01-01T23:59:59.000Z

    Language in social media is rich with linguistic innovations, most strikingly in the new words and spellings that constantly enter the lexicon. Despite assertions about the power of social media to connect people across the world, we find that many of these neologisms are restricted to geographically compact areas. Even for words that become ubiquituous, their growth in popularity is often geographical, spreading from city to city. Thus, social media text offers a unique opportunity to study the diffusion of lexical change. In this paper, we show how an autoregressive model of word frequencies in social media can be used to induce a network of linguistic influence between American cities. By comparing the induced network with the geographical and demographic characteristics of each city, we can measure the factors that drive the spread of lexical innovation.

  17. Turbulent diffusion with rotation or magnetic fields

    E-Print Network [OSTI]

    Brandenburg, Axel; Vasil, Geoffrey M

    2009-01-01T23:59:59.000Z

    The turbulent diffusion tensor describing the evolution of the mean concentration of a passive scalar is investigated for forced turbulence either in the presence of rotation or a magnetic field. With rotation the Coriolis force causes a sideways deflection of the flux of mean concentration. Within the magnetohydrodynamics approximation there is no analogous effect from the magnetic field because the effects on the flow do not depend on the sign of the field. Both rotation and magnetic fields tend to suppress turbulent transport, but this suppression is weaker in the direction along the magnetic field. Turbulent transport along the rotation axis is not strongly affected by rotation, except on shorter length scales, i.e. when the scale of the variation of the mean field becomes comparable with the scale of the energy-carrying eddied.

  18. Diffusion of irreversible energy technologies under uncertainty

    SciTech Connect (OSTI)

    Cacallo, J.D.; Sutherland, R.J.

    1993-09-01T23:59:59.000Z

    This paper presents a model of technology diffusion is consistent with characteristics of participants in most energy markets. Whereas the models used most widely for empirical research are based on the assumption that the extended delays in adoption of cost-saving innovations are the result of either lack of knowledge about the new processes or heterogeneity across potential adopters, the model presented in this paper is based on the strategic behavior by firms. The strategic interdependence of the firms` decisions is rooted in spillover effects associated with an inability to exclude others from the learning-by-doing acquired when a firm implements a new technology. The model makes extensive use of recent developments in investment theory as it relates irreversible investments under uncertainty.

  19. Diffuse gamma-rays from galactic halos

    E-Print Network [OSTI]

    M. Pohl

    1996-03-12T23:59:59.000Z

    Here we review our current knowledge on diffuse gamma-rays from galactic halos. Estimates of the relative contribution of the various emission processes at low and high latitudes are compared to the data over 6 decades in energy. The observed spectral shape differs from what was expected, especially at ver low and very high energies. In the latter case, above 1 GeV, the sky emission related to gas exceeds the expected pi^0 decay spectrum. At energies below 1 MeV the relatively high gamma-ray intensity indicates at high density of nearly relativistic electrons which would have a strong influence on the energy and ionisation balance of the interstellar medium. Given the EGRET results for the Magellanic Clouds the gamma-ray emissivity in the outer halo is probably small, so that a substantial amount of baryonic dark matter may be hidden at 20-50 kpc radius without inducing observable gamma-ray emission.

  20. A Simplified HTTR Diffusion Theory Benchmark

    SciTech Connect (OSTI)

    Rodolfo M. Ferrer; Abderrafi M. Ougouag; Farzad Rahnema

    2010-10-01T23:59:59.000Z

    The Georgia Institute of Technology (GA-Tech) recently developed a transport theory benchmark based closely on the geometry and the features of the HTTR reactor that is operational in Japan. Though simplified, the benchmark retains all the principal physical features of the reactor and thus provides a realistic and challenging test for the codes. The purpose of this paper is twofold. The first goal is an extension of the benchmark to diffusion theory applications by generating the additional data not provided in the GA-Tech prior work. The second goal is to use the benchmark on the HEXPEDITE code available to the INL. The HEXPEDITE code is a Green’s function-based neutron diffusion code in 3D hexagonal-z geometry. The results showed that the HEXPEDITE code accurately reproduces the effective multiplication factor of the reference HELIOS solution. A secondary, but no less important, conclusion is that in the testing against actual HTTR data of a full sequence of codes that would include HEXPEDITE, in the apportioning of inevitable discrepancies between experiment and models, the portion of error attributable to HEXPEDITE would be expected to be modest. If large discrepancies are observed, they would have to be explained by errors in the data fed into HEXPEDITE. Results based on a fully realistic model of the HTTR reactor are presented in a companion paper. The suite of codes used in that paper also includes HEXPEDITE. The results shown here should help that effort in the decision making process for refining the modeling steps in the full sequence of codes.

  1. Internal pipe attachment mechanism

    DOE Patents [OSTI]

    Bast, Richard M. (Livermore, CA); Chesnut, Dwayne A. (Pleasanton, CA); Henning, Carl D. (Livermore, CA); Lennon, Joseph P. (Livermore, CA); Pastrnak, John W. (Livermore, CA); Smith, Joseph A. (Livermore, CA)

    1994-01-01T23:59:59.000Z

    An attachment mechanism for repairing or extending fluid carrying pipes, casings, conduits, etc. utilizing one-way motion of spring tempered fingers to provide a mechanical connection between the attachment mechanism and the pipe. The spring tempered fingers flex to permit insertion into a pipe to a desired insertion depth. The mechanical connection is accomplished by reversing the insertion motion and the mechanical leverage in the fingers forces them outwardly against the inner wall of the pipe. A seal is generated by crushing a sealing assembly by the action of setting the mechanical connection.

  2. Internal pipe attachment mechanism

    DOE Patents [OSTI]

    Bast, R.M.; Chesnut, D.A.; Henning, C.D.; Lennon, J.P.; Pastrnak, J.W.; Smith, J.A.

    1994-12-13T23:59:59.000Z

    An attachment mechanism is described for repairing or extending fluid carrying pipes, casings, conduits, etc. utilizing one-way motion of spring tempered fingers to provide a mechanical connection between the attachment mechanism and the pipe. The spring tempered fingers flex to permit insertion into a pipe to a desired insertion depth. The mechanical connection is accomplished by reversing the insertion motion and the mechanical leverage in the fingers forces them outwardly against the inner wall of the pipe. A seal is generated by crushing a sealing assembly by the action of setting the mechanical connection. 6 figures.

  3. Strain effect on the adsorption, diffusion, and molecular dissociation of hydrogen on Mg (0001) surface

    SciTech Connect (OSTI)

    Lei, Huaping; Wang, Caizhuang; Yao, Yongxin; Hupalo, Myron [Ames Laboratory, USDOE, Ames, Iowa 50011 (United States)] [Ames Laboratory, USDOE, Ames, Iowa 50011 (United States); Wang, Yangang [Ames Laboratory, USDOE, Ames, Iowa 50011 (United States) [Ames Laboratory, USDOE, Ames, Iowa 50011 (United States); Supercomputing Center of Computer Network Information Center, CAS, Beijing 100190 (China); McDougall, Dan; Tringides, Michael; Ho, Kaiming [Ames Laboratory, USDOE, Ames, Iowa 50011 (United States) [Ames Laboratory, USDOE, Ames, Iowa 50011 (United States); Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States)

    2013-12-14T23:59:59.000Z

    The adsorption, diffusion, and molecular dissociation of hydrogen on the biaxially strained Mg (0001) surface have been systematically investigated by the first principle calculations based on density functional theory. When the strain changes from the compressive to tensile state, the adsorption energy of H atom linearly increases while its diffusion barrier linearly decreases oppositely. The dissociation barrier of H{sub 2} molecule linearly reduces in the tensile strain region. Through the chemical bonding analysis including the charge density difference, the projected density of states and the Mulliken population, the mechanism of the strain effect on the adsorption of H atom and the dissociation of H{sub 2} molecule has been elucidated by an s-p charge transfer model. With the reduction of the orbital overlap between the surface Mg atoms upon the lattice expansion, the charge transfers from p to s states of Mg atoms, which enhances the hybridization of H s and Mg s orbitals. Therefore, the bonding interaction of H with Mg surface is strengthened and then the atomic diffusion and molecular dissociation barriers of hydrogen decrease accordingly. Our works will be helpful to understand and to estimate the influence of the lattice deformation on the performance of Mg-containing hydrogen storage materials.

  4. Identification of As-vacancy complexes in Zn-diffused GaAs

    SciTech Connect (OSTI)

    Elsayed, M. [Department of Physics, Martin Luther University Halle, 06099 Halle (Germany); Department of Physics, Faculty of Science, Minia University, 61519 Minia (Egypt); Krause-Rehberg, R. [Department of Physics, Martin Luther University Halle, 06099 Halle (Germany); Korff, B. [Bremen Center for Computational Materials Science, University Bremen, 28359 Bremen (Germany); Richter, S. [Fraunhofer Center for Silicon Photovoltaics CSP, 06120 Halle (Saale) (Germany); Leipner, H. S. [Center of Materials Science, Martin Luther University Halle, 06099 Halle (Germany)

    2013-03-07T23:59:59.000Z

    We have used positron annihilation spectroscopy to study the introduction of point defects in Zn-diffused semi-insulating GaAs. The diffusion was performed by annealing the samples for 2 h at 950 Degree-Sign C. The samples were etched in steps of 7 {mu}m. Both Doppler broadening using slow positron beam and lifetime spectroscopy studies were performed after each etching step. Both techniques showed the existence of vacancy-type defects in a layer of about 45 {mu}m. Secondary ion mass spectroscopy measurements illustrated the presence of Zn at high level in the sample almost up to the same depth. Vacancy-like defects as well as shallow positron traps were observed by lifetime measurements. We distinguish two kinds of defects: As vacancy belongs to defect complex, bound to most likely one Zn atom incorporated on Ga sublattice, and negative-ion-type positron traps. Zn acceptors explained the observation of shallow traps. The effect of Zn was evidenced by probing GaAs samples annealed under similar conditions but without Zn treatment. A defect-free bulk lifetime value is detected in this sample. Moreover, our positron annihilation spectroscopy measurements demonstrate that Zn diffusion in GaAs system is governed by kick-out mechanism.

  5. Bulk diffusion induced structural modifications of carbon-transition metal nanocomposite films

    SciTech Connect (OSTI)

    Berndt, M.; Abrasonis, G.; Kovacs, Gy. J.; Krause, M.; Munnik, F.; Heller, R.; Kolitsch, A.; Moeller, W.

    2011-03-15T23:59:59.000Z

    The influence of transition metal (TM = V,Co,Cu) type on the bulk diffusion induced structural changes in carbon:TM nanocomposite films is investigated. The TMs have been incorporated into the carbon matrix via ion beam co-sputtering, and subsequently the films have been vacuum annealed in the temperature range of 300 - 700 deg. C. The structure of both the dispersed metal rich and the carbon matrix phases has been determined by a combination of elastic recoil detection analysis, x-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The as-grown films consist of carbidic (V and Co) and metallic (Cu) nanoparticles dispersed in the carbon matrix. Thermal annealing induces surface segregation of Co and Cu starting at {>=} 500 deg. C, preceded by the carbide-metal transformation of Co-carbide nanoparticles at {approx} 300 deg. C. No considerable morphological changes occur in C:V films. In contrast to the surface diffusion dominated regime where all the metals enhance the six-fold ring clustering of C, in the bulk diffusion controlled regime only Co acts as a catalyst for the carbon graphitization. These results are consistent with the metal-induced crystallization mechanism in the C:Co films. The results are discussed on the basis of the metal-carbide phase stability, carbon solubility in metals or their carbides, and interface species.

  6. Thermal imaging measurement and correlation of thermal diffusivity in continuous fiber ceramic composites

    SciTech Connect (OSTI)

    Sun, J.G.; Deemer, C.; Ellingson, W.A. [Argonne National Lab., IL (United States). Energy Technology Div.; Easler, T.E.; Szweda, A. [Dow Corning Corp., Midland, MI (United States); Craig, P.A. [DuPont Lanxide Composites Inc., Newark, DE (United States)

    1997-09-01T23:59:59.000Z

    Continuous fiber ceramic matrix composites (CFCCs) are currently being developed for a variety of high-temperature applications, including use in advanced heat engines. For such composites, knowledge of porosity distribution and presence of defects is important for optimizing mechanical and thermal behavior of the components. The assessment of porosity and its distribution is also necessary during composite processing to ensure component uniformity. To determine the thermal properties of CFCC materials, and particularly for detecting defects and nonuniformities, the authors have developed an infrared thermal imaging method to provide a single-shot full-field measurement of thermal diffusivity distributions in large components. This method requires that the back surface of a specimen receives a thermal pulse of short duration and that the temperature of the front surface is monitored as a function of time. The system has been used to measure thermal diffusivities of several CFCC materials with known porosity or density values, including SYLRAMIC{trademark} SiC/SiNC composite samples from Dow Corning and SiC/SiC and enhanced SiC/SiC samples from DuPont Lanxide Composites, to determine the relationship of thermal diffusivity to component porosity or density.

  7. Convergence Speed of GARCH Option Price to Diffusion Option Price

    E-Print Network [OSTI]

    Chaudhuri, Sanjay

    Convergence Speed of GARCH Option Price to Diffusion Option Price Jin-Chuan Duan, Yazhen Wang that as the time interval between two consecutive observations shrinks to zero, a properly constructed GARCH model will weakly converge to a bivariate diffusion. Naturally the European option price under the GARCH model

  8. ENERGY DIFFUSION IN HARMONIC SYSTEM WITH CONSERVATIVE NOISE

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    systems or lattice dimension d 3, where the thermal diffusivity is finite. 1. Introduction Lattice the evolution of the energy and identify the thermal diffusivity. In the harmonic chain with noise this agrees to what it is expected for deterministic anharmonic dynamics. In this article we consider the same

  9. Optical processing furnace with quartz muffle and diffuser plate

    DOE Patents [OSTI]

    Sopori, Bhushan L. (Denver, CO)

    1996-01-01T23:59:59.000Z

    An optical furnace for annealing a process wafer comprising a source of optical energy, a quartz muffle having a door to hold the wafer for processing, and a quartz diffuser plate to diffuse the light impinging on the quartz muffle; a feedback system with a light sensor located in the wall of the muffle is also provided for controlling the source of optical energy.

  10. Experimental determination of the boundary condition for diffuse photons

    E-Print Network [OSTI]

    Zhu, Xiangdong

    of a turbid medium, the light transport is described by the diffusion approxima- tion of the radiative of a turbid medium within a few transport mean free paths, the diffusion equation is no longer satisfied light transport through a turbid (i.e., highly scatter- ing) medium and in imaging objects

  11. Beta Advection-Diffusion Model Columbia Basin Research

    E-Print Network [OSTI]

    Washington at Seattle, University of

    Beta Advection-Diffusion Model Jim Norris Columbia Basin Research University of Washington Box Model (SSM) is loosely called a Beta Advection-Diffusion model. The SSM estimates a single parameter this single parameter characterized fish migration. The purpose of this note is to define the Beta Advection

  12. Peer Effects in the Diffusion of Solar Photovoltaic Panels

    E-Print Network [OSTI]

    Lee, Daeyeol

    Peer Effects in the Diffusion of Solar Photovoltaic Panels Bryan Bollinger NYU Stern School base of consumers in the reference group. We study the diffusion of solar photovoltaic panels of an environmentally beneficial technology, solar photovoltaic (PV) panels. Policymakers are particularly interested

  13. Uniformly Accurate Diffusive Relaxation Schemes for Multiscale Transport Equations

    E-Print Network [OSTI]

    , radiative transfer, and transport equations for waves in random media, have a diffusive scaling that leads #12; 1. Introduction Many transport equations, such as the neutron transport [CZ], radiative transferUniformly Accurate Diffusive Relaxation Schemes for Multiscale Transport Equations Shi JIN y

  14. Diffusion MRI of Complex Tissue Structure David Solomon Tuch

    E-Print Network [OSTI]

    Duncan, James S.

    Diffusion MRI of Complex Tissue Structure by David Solomon Tuch B.A., Physics, University Solomon Tuch Submitted to the Division of Health Sciences and Technology on January 11, 2002, in partial to be beyond the scope of diffusion imaging methodology. Thesis Supervisor: Van Jay Wedeen Title: Associate

  15. Modeling of Spectralon diffusers for radiometric calibration in remote sensing

    E-Print Network [OSTI]

    Sprik, Rudolf

    function (BRDF) of the diffuser outside the measured calibration set, or a model of the degradation, and anisotropy of the scattering. We also describe the result of modeling the degradation of a Spectralon diffuser after deposi- tion, under UV radiation, of a silicone layer. © 2003 Society of Photo

  16. Slippery diffusion-limited aggregation Clair R. Seager1,

    E-Print Network [OSTI]

    Weeks, Eric R.

    can translationally diffuse over the surface of the other. By contrast, shear-rigid bonding createsSlippery diffusion-limited aggregation Clair R. Seager1, * and Thomas G. Mason2, 1 Department attractions in liquids form irreversible "slippery" bonds that are not shear-rigid. Through event

  17. Diffusion with dissolution and precipitation in a porous media

    E-Print Network [OSTI]

    Herbin, Raphaèle

    Diffusion with dissolution and precipitation in a porous media approximation by a finite volume. Quelques tests numériques sont ensuite montrés. KEYWORDS: diffusion, dissolution­precipitation, porous­ ficiency of such disposals relies on material barriers. For such a use, cement concrete offers

  18. Diffusion with dissolution and precipitation in a porous media

    E-Print Network [OSTI]

    Herbin, Raphaèle

    Diffusion with dissolution and precipitation in a porous media approximation by a finite volume numériques sont ensuite montrés. KEYWORDS: diffusion, dissolution-precipitation, porous media, finite volumes barriers. For such a use, cement concrete offers the advantage of having a weak porosity. However, disposal

  19. Uranium and cesium diffusion in fuel cladding of electrogenerating channel

    SciTech Connect (OSTI)

    Vasil’ev, I. V., E-mail: fnti@mail.ru; Ivanov, A. S.; Churin, V. A. [National Research Center Kurchatov Institute (Russian Federation)

    2014-12-15T23:59:59.000Z

    The results of reactor tests of a carbonitride fuel in a single-crystal cladding from a molybdenum-based alloy can be used in substantiating the operational reliability of fuels in developing a project of a megawatt space nuclear power plant. The results of experimental studies of uranium and cesium penetration into the single-crystal cladding of fuel elements with a carbonitride fuel are interpreted. Those fuel elements passed nuclear power tests in the Ya-82 pilot plant for 8300 h at a temperature of about 1500°C. It is shown that the diffusion coefficients for uranium diffusion into the cladding are virtually coincident with the diffusion coefficients measured earlier for uranium diffusion into polycrystalline molybdenum. It is found that the penetration of uranium into the cladding is likely to occur only in the case of a direct contact between the cladding and fuel. The experimentally observed nonmonotonic uranium-concentration profiles are explained in terms of predominant uranium diffusion along grain boundaries. It is shown that a substantially nonmonotonic behavior observed in our experiment for the uranium-concentration profile may be explained by the presence of a polycrystalline structure of the cladding in the surface region from its inner side. The diffusion coefficient is estimated for the grain-boundary diffusion of uranium. The diffusion coefficients for cesium are estimated on the basis of experimental data obtained in the present study.

  20. Vacancy mediated substitutional diffusion in binary crystalline solids

    E-Print Network [OSTI]

    Ceder, Gerbrand

    Vacancy mediated substitutional diffusion in binary crystalline solids Anton Van der Ven a,*, Hui coefficients of substi- tutional alloys from first principles. The focus is restricted to vacancy mediated and grain boundaries that can act as vacancy sources) and diffusion in a solid containing a continuous

  1. Thermal diffusivity mapping of 4D carbon-carbon composites

    SciTech Connect (OSTI)

    Wang, H.; Dinwiddie, R.B.

    1997-03-01T23:59:59.000Z

    High resolution, 2-D thermal diffusivity maps of carbon-carbon composites were obtained by a state-of-the-art infrared thermal imaging system. Unlike the traditional single-point IR detector used for thermal diffusivity measurements, the IR camera is capable of capturing images in its 256 x 256 pixel Focal Plane Array detector in a snap-shot mode. The camera takes up to 200 images at a rate of 120 frames/second. The temperature resolution of the Ir camera is 0.015 C and the spatial resolution is 20 {micro}m. Thermal diffusivity was calculated for each pixel. Four-direction carbon-carbon composites were used for the thermal diffusivity mapping study. The fiber bundles along the heat flow direction were found to have 25% higher diffusivity values than the surrounding matrix. The diffusivity map also showed detailed local variations in diffusivity which were impossible to measure using a single-point detector. Accurate diffusivity maps are very important to the design of composite materials.

  2. DYNAMIC MODELING AND CONTROL OF REACTIVE DISTILLATION FOR HYDROGENATION OF BENZENE

    E-Print Network [OSTI]

    Aluko, Obanifemi

    2010-01-16T23:59:59.000Z

    . Otherwise, a rate-based mechanism is employed to describe the material and enrgy transfer between the liquid and vapor phases. The chemical reactions also introduce a structural difference between the models. Indeed, the chemical reactions can be either...

  3. The influence of TiSi2 and CoSi2 growth on Si native point defects: The role of the diffusing species

    E-Print Network [OSTI]

    Florida, University of

    from codeposited metal and Si. The as-deposited films had the compositions Ti, TiSi0.8 , TiSi2 undersaturation.3 Nevertheless, the mechanism by which silicide films effect a perturbance in the point defect, causing a va- cancy supersaturation. The formation of CoSi2 from CoSi proceeds via diffusion of metal

  4. 30TH INTERNATIONAL COSMIC RAY CONFERENCE Measuring TeV Gamma-Ray Diffuse Emission from the Galactic Plane with Milagro

    E-Print Network [OSTI]

    Moskalenko, Igor V.

    mechanisms such as the annihilation of dark matter particles [5]. At TeV energies, Milagro has previously@lanl.gov Abstract: Diffuse gamma radiation produced in the interaction of cosmic-ray particles with matter and long observation time the Milagro Gamma-Ray Observatory ­ a water Cherenkov detector in New Mexico, USA

  5. Programmable Mechanical Metamaterials

    E-Print Network [OSTI]

    Bastiaan Florijn; Corentin Coulais; Martin van Hecke

    2014-07-17T23:59:59.000Z

    We create mechanical metamaterials whose response to uniaxial compression can be programmed by lateral confinement, allowing monotonic, non-monotonic and hysteretic behavior. These functionalities arise from a broken rotational symmetry which causes highly nonlinear coupling of deformations along the two primary axes of these metamaterials. We introduce a soft mechanism model which captures the programmable mechanics, and outline a general design strategy for confined mechanical metamaterials. Finally, we show how inhomogeneous confinement can be explored to create multi stability and giant hysteresis.

  6. Mechanical & Industrial Engineering

    E-Print Network [OSTI]

    Mountziaris, T. J.

    Mechanical & Industrial Engineering Mario A. Rotea Professor and Department Head #12;2Mechanical & Industrial Engineering Outline · Undergraduate Degree Programs · Graduate Degree Programs · The Faculty · The Research · Summary #12;3Mechanical & Industrial Engineering Undergraduate Programs ­ BSME & BSIE 0 20 40 60

  7. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    efficient energy systems. Evelyn N. Wang is an Associate Professor in the Mechanical Engineering DepartmentMechanical engineering Department Seminar Evelyn Wang Depaprtment of Mechanical Engineering MIT Nanoengineered Surfaces: Transport Phenomena and Energy Applications 11:00 AM Friday, 5 April 2013 Room 245, 110

  8. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    Mechanical engineering Department Seminar Domitilla Del Vecchio Department of Mechanical. A near future is envisioned in which re- engineered bacteria will turn waste into energy and kill cancer, she joined the Department of Mechanical Engineering and the Laboratory for Information and Decision

  9. Mechanical & Aerospace Engineering

    E-Print Network [OSTI]

    in Mechanical Engineering at the School for Engineering of Matter, Transport and Energy, working in Dr. MarcusMechanical & Aerospace Engineering The atomization of a liquid jet by a high speed cross.S.E. degree in mechanical engineering from Amirkabir University of Technology in 2006 and M.S. degree

  10. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    Lin, Xi

    Mechanical engineering Department Seminar Shuodao Wang Postdoctoral Fellow University of Illinois, Urbana-Champaign Mechanical Design and Fabrication Techniques for Bio-Electronic Systems 11:00 AM Friday that bridge this gap in mechanics and form will create new opportunities in bio-inspired and bio

  11. Mechanical and Aerospace Engineering

    E-Print Network [OSTI]

    Mechanical and Aerospace Engineering Abstract Solid materials used in energy conversion and storage that couples the mechanical and chemical (or electrochemical) fields in solids via the use of stress-chemo- mechanical theory, two examples of practical interest will be discussed, namely, solid oxide fuel cells

  12. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    Lin, Xi

    Mechanical engineering Department Seminar Maureen Lynch Postdoctoral Fellow Cornell University Mechanical Loading Decreases Osteolysis and Tumor Formation via Effects on Bone Remodeling 11:00 AM Friday to mechanical stimuli in the skeleton, yet the role of biomechanical loading remains poorly characterized

  13. UNSATURATED SOIL MECHANICS IMPLEMENTATION

    E-Print Network [OSTI]

    Minnesota, University of

    UNSATURATED SOIL MECHANICS IMPLEMENTATION DURING PAVEMENT CONSTRUCTION QUALITY ASSURANCE Mn !! Performance Based Construction QA !! Unsaturated Soil Mechanics !! What We've Learned !! Next Steps #12.6-6.0 5 - 7 19 0.8 5 7 - 9 24 1.1 4 9 - 11 28 1.2 4 #12;Unsaturated Soil Mechanics #12;Fundamentals

  14. Victor Yakhot Mechanical Engineering

    E-Print Network [OSTI]

    Lin, Xi

    to flows of strongly non-linear fluids relevant for mechanical engineering, polymers and bio-fluid dynamicsVictor Yakhot Mechanical Engineering UniversalReynoldsNumberofTransition,Renormalizationand Mechanical Engineering 11 AM Friday, October 31st Room 245, 110 Cummington Mall Refreshments served at 10

  15. Oxygen self-diffusion ``fast-paths'' in titanite single crystals and a general method for deconvolving self-diffusion

    E-Print Network [OSTI]

    Watson, E. Bruce

    Oxygen self-diffusion ``fast-paths'' in titanite single crystals and a general method most other minerals, titanite rarely if ever forms perfect crystals. In addition to the point defects could occur. During the course of an experimental study of oxygen lattice diffusion in titanite, we

  16. Quadratic and Cubic ReactionDiffusion Fronts*

    E-Print Network [OSTI]

    Showalter, Kenneth

    's student, Herr cand. Meinecke, moved a wire loop along the test tube to mark the position in the cytoplasm of frog oocytes [9], where calcium-induced calcium release provides a mechanism akin to auto- catalysis in chemical systems. Front-like calcium waves have also been found to occur on the surface

  17. Impurity Diffusion Coefficients of Al and Zn in Mg Determined from Solid-to-Solid Diffusion Couples

    SciTech Connect (OSTI)

    Kammerer, Catherine [University of Central Florida, Orlando; Kulkarni, Nagraj S [ORNL; Warmack, Robert J Bruce [ORNL; Perry, Kelly A [ORNL; Belova, Irina [University of Newcastle, NSW, Australia; Murch, Prof. Graeme [University of Newcastle, NSW, Australia; Sohn, Yong Ho [University of Central Florida

    2013-08-01T23:59:59.000Z

    Increasing use and development of lightweight Mgalloys have led to the desire for more fundamental research in and understanding of Mg-based systems. As property enhancing components, Al and Zn are two of the most important and common alloying elements for Mg-alloys. We have investigated the concentration dependent interdiffusion of Al and Zn in Mg using diffusion couples of pure polycrystalline Mg mated to Mg solid solutions containing either <9 at.% Al or <3 at.% Zn. Concentration profiles were determined by electron micro-probe microanalysis of the diffusion zone. The interdiffusion coefficients were determined by the classical Boltzmann-Matano method within the Mg solid solution. As the concentration of Al or Zn approaches the dilute ends, we employ an analytical approach based on the Hall method to estimate the impurity diffusion coefficients. Results of Al and Zn impurity diffusion in Mg are reported and compared to published impurity diffusion coefficients typically determined by thin film techniques.

  18. Mechanical seal assembly

    DOE Patents [OSTI]

    Kotlyar, Oleg M. (Salt Lake City, UT)

    2002-01-01T23:59:59.000Z

    An improved mechanical seal assembly is provided for sealing rotating shafts with respect to their shaft housings, wherein the rotating shafts are subject to substantial axial vibrations. The mechanical seal assembly generally includes a rotating sealing ring fixed to the shaft, a non-rotating sealing ring adjacent to and in close contact with the rotating sealing ring for forming an annular seal about the shaft, and a mechanical diode element that applies a biasing force to the non-rotating sealing ring by means of hemispherical joint. The alignment of the mechanical diode with respect to the sealing rings is maintained by a series of linear bearings positioned axially along a desired length of the mechanical diode. Alternative embodiments include mechanical or hydraulic amplification components for amplifying axial displacement of the non-rotating sealing ring and transfering it to the mechanical diode.

  19. Mechanical seal assembly

    DOE Patents [OSTI]

    Kotlyar, Oleg M. (Salt Lake City, UT)

    2001-01-01T23:59:59.000Z

    An improved mechanical seal assembly is provided for sealing rotating shafts with respect to their shaft housings, wherein the rotating shafts are subject to substantial axial vibrations. The mechanical seal assembly generally includes a rotating sealing ring fixed to the shaft, a non-rotating sealing ring adjacent to and in close contact with the rotating sealing ring for forming an annular seal about the shaft, and a mechanical diode element that applies a biasing force to the non-rotating sealing ring by means of hemispherical joint. The alignment of the mechanical diode with respect to the sealing rings is maintained by a series of linear bearings positioned axially along a desired length of the mechanical diode. Alternative embodiments include mechanical or hydraulic amplification components for amplifying axial displacement of the non-rotating sealing ring and transferring it to the mechanical diode.

  20. Understanding the Regional Variability of Eddy Diffusivity in the Pacific Sector of the Southern Ocean

    E-Print Network [OSTI]

    Shuckburgh, Emily

    A diagnostic framework is presented, based on the Nakamura effective diffusivity, to investigate the regional variation in eddy diffusivity. Comparison of three different diffusivity calculations enables the effects of ...

  1. Flux-Limited Diffusion Approximation Models of Giant Planet Formation by Disk Instability

    E-Print Network [OSTI]

    Alan P. Boss

    2008-01-28T23:59:59.000Z

    Both core accretion and disk instability appear to be required as formation mechanisms in order to explain the entire range of giant planets found in extrasolar planetary systems. Disk instability is based on the formation of clumps in a marginally-gravitationally unstable protoplanetary disk. These clumps can only be expected to contract and survive to become protoplanets if they are able to lose thermal energy through a combination of convection and radiative cooling. Here we present several new three dimensional, radiative hydrodynamics models of self-gravitating protoplanetary disks, where radiative transfer is handled in the flux-limited diffusion approximation. We show that while the flux-limited models lead to higher midplane temperatures than in a diffusion approximation model without the flux-limiter, the difference in temperatures does not appear to be sufficiently high to have any significant effect on the formation of self-gravitating clumps. Self-gravitating clumps form rapidly in the models both with and without the flux-limiter. These models suggest that the reason for the different outcomes of numerical models of disk instability by different groups cannot be attributed solely to the handling of radiative transfer, but rather appears to be caused by a range of numerical effects and assumptions. Given the observational imperative to have disk instability form at least some extrasolar planets, these models imply that disk instability remains as a viable giant planet formation mechanism.

  2. Molecular Characterization of Organic Content of Soot along the Centerline of a Coflow Diffusion Flame

    SciTech Connect (OSTI)

    Cain, Jeremy P.; Laskin, Alexander; Kholghy, Mohammad Reza; Thomson, Murray; Wang, Hai

    2014-10-29T23:59:59.000Z

    High-resolution mass spectrometry coupled with nanospray desorption electrospray ionization was used to probe chemical constituents of young soot particles sampled along the centerline of a coflow diffusion flame of a three-component Jet-A1 surrogate. In lower positions where particles are transparent to light extinction (n= 632.8 nm), peri-condensed polycyclic aromatic hydrocarbons (PAHs) are found to be the major components of the particle material. These particles become enriched with aliphatic components as they grow in mass and size. Before carbonization occurs, the constituent species in young soot particles are aliphatic and aromatic compounds 200-600 amu in mass, some of which are oxygenated. Particles dominated by PAHs or mixtures of PAHs and aliphatics can both exhibit liquid-like appearance observed by electron microscopy and be transparent to visible light. The variations in chemical composition observed here indicate that the molecular processes of soot formation in coflow diffusion flames may be more complex than previously thought. For example, the mass growth and enrichment of aliphatic components in an initially, mostly aromatic structure region of the flame that is absent of H atoms or other free radicals indicates that there must exist at least another mechanism of soot mass growth in addition to the hydrogen-abstraction-carbon addition mechanism currently considered in fundamental models of soot formation.

  3. Spectral Components Analysis of Diffuse Emission Processes

    SciTech Connect (OSTI)

    Malyshev, Dmitry; /KIPAC, Menlo Park

    2012-09-14T23:59:59.000Z

    We develop a novel method to separate the components of a diffuse emission process based on an association with the energy spectra. Most of the existing methods use some information about the spatial distribution of components, e.g., closeness to an external template, independence of components etc., in order to separate them. In this paper we propose a method where one puts conditions on the spectra only. The advantages of our method are: 1) it is internal: the maps of the components are constructed as combinations of data in different energy bins, 2) the components may be correlated among each other, 3) the method is semi-blind: in many cases, it is sufficient to assume a functional form of the spectra and determine the parameters from a maximization of a likelihood function. As an example, we derive the CMB map and the foreground maps for seven yeas of WMAP data. In an Appendix, we present a generalization of the method, where one can also add a number of external templates.

  4. Diffuse interstellar bands in M33

    E-Print Network [OSTI]

    Smith, Keith T; Evans, Christopher J; Cox, Nick L J; Sarre, Peter J

    2013-01-01T23:59:59.000Z

    We present the first sample of diffuse interstellar bands (DIBs) in the nearby galaxy M33. Studying DIBs in other galaxies allows the behaviour of the carriers to be examined under interstellar conditions which can be quite different from those of the Milky Way, and to determine which DIB properties can be used as reliable probes of extragalactic interstellar media. Multi-object spectroscopy of 43 stars in M33 has been performed using Keck/DEIMOS. The stellar spectral types were determined and combined with literature photometry to determine the M33 reddenings E(B-V)_M33. Equivalent widths or upper limits have been measured for the {\\lambda}5780 DIB towards each star. DIBs were detected towards 20 stars, demonstrating that their carriers are abundant in M33. The relationship with reddening is found to be at the upper end of the range observed in the Milky Way. The line of sight towards one star has an unusually strong ratio of DIB equivalent width to E(B-V)_M33, and a total of seven DIBs were detected towards...

  5. The Hidden Geometry of Attention Diffusion

    E-Print Network [OSTI]

    Wu, Lingfei; Janssen, Marco; Zhang, Jiang; Zhao, Min

    2015-01-01T23:59:59.000Z

    It is difficult to develop quantitative hypotheses to describe the diffusion of information among users, because, in theory, information resources can have an infinite number of copies. And this theoretical possibility has become a reality in an age of information explosion, when a Twitter meme may spread rapidly to millions of users in a few hours. To address this issue, we propose to study the transportation of users' attention between information resources. We use clicks as a proxy of attention and construct attention networks using the browsing log files from 1,000 Web forums. Our previous research discovered the scaling relationship between clicks and users with an exponent $\\theta$ that characterizes the efficiency of forums in spreading information. In this paper we propose a geometric model to explain this scaling property. We view attention networks as $d$-dimensional flow-balls that satisfy $\\theta=(d+1)/d$ and we find that the time-invariant parameter $d$ can be estimated from the spatial distribut...

  6. Puzzling Phenomenon of Diffuse Interstellar Bands

    E-Print Network [OSTI]

    B. Wszolek

    2007-12-10T23:59:59.000Z

    The discovery of the first diffuse interstellar bands (DIBs) dates back to the pioneering years of stellar spectroscopy. Today, we know about 300 absorption structures of this kind. There exists a great variety of the profiles and intensities of DIBs, so they can not be readily described, classified or characterized. To the present day no reliable identification of the DIBs' carriers has been found. Many carriers of DIBs have been proposed over the years. They ranged from dust grains to free molecules of different kinds, and to more exotic specimens, like hydrogen negative ion. Unfortunately, none of them is responsible for observed DIBs. Furthermore, it was shown that a single carrier cannot be responsible for all known DIBs. It is hard to estimate how many carriers can participate in producing these bands. The problem is further complicated by the fact that to this day it is still impossible to find any laboratory spectrum of any substance which would match the astrophysical spectra. Here, a historical outline concerning DIBs is followed by a brief description of their whole population. Then, a special attention is focused on the procedures trying to extract spectroscopic families within the set of all known DIBs.

  7. Oxygen and nitrogen diffusion in ?-hafnium from first principles

    SciTech Connect (OSTI)

    O'Hara, Andrew; Demkov, Alexander A., E-mail: demkov@physics.utexas.edu [Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States)

    2014-05-26T23:59:59.000Z

    We use a combination of density functional theory and multistate diffusion formalism to analyze the diffusion of oxygen and nitrogen in technologically important hafnium metal. Comparing the local density approximation and the Perdew-Burke-Ernzerhof version of the generalized gradient approximation, we find that a better description of the hafnium lattice in the latter results in the correct sequence of stable and transition states for oxygen interstitials leading to essentially quantitative agreement with experiment. For oxygen diffusion, we find an isotropic temperature-dependent diffusion coefficient of D=0.082e{sup ?2.04/k{sub B}T}cm{sup 2}s{sup ?1} utilizing interstitial sites with hexahedral and octahedral coordination. For the diffusivity of nitrogen, we find that an additional stable interstitial site, the crowdion site, exists and that the diffusion coefficient is D=0.15e{sup ?2.68/k{sub B}T}cm{sup 2}s{sup ?1}. Our results also reproduce the experimental observation that nitrogen diffusivity is lower than that of oxygen in hafnium.

  8. Effect of elasticity of wall on diffusion in nano channel

    SciTech Connect (OSTI)

    Tankeshwar, K., E-mail: tankesh@pu.ac.in [Computer Centre, Panjab University Chandigarh,- 160014 (India); Srivastava, Sunita [Department of Physics, Panjab University, Chandigarh 160014 (India)

    2014-04-24T23:59:59.000Z

    Confining walls of nano channel are taken to be elastic to study their effect on the diffusion coefficient of fluid flowing through the channel. The wall is elastic to the extent that it responses to molecular pressure exerted by fluid. The model to study diffusion is based on microscopic considerations. Results obtained for fluid confining to 20 atomic diameter width contrasted with results obtained by considering rigid and smooth wall. The effect of roughness of wall on diffusion can be compensated by the elastic property of wall.

  9. Energy diffusion in strongly driven quantum chaotic systems

    E-Print Network [OSTI]

    P. V. Elyutin

    2005-04-14T23:59:59.000Z

    The energy evolution of a quantum chaotic system under the perturbation that harmonically depends on time is studied for the case of large perturbation, in which the rate of transition calculated from the Fermi golden rule exceeds the frequency of perturbation. It is shown that the energy evolution retains its diffusive character, with the diffusion coefficient that is asymptotically proportional to the magnitude of perturbation and to the square root of the density of states. The results are supported by numerical calculation. They imply the absence of the quantum-classical correspondence for the energy diffusion and the energy absorption in the classical limit $\\hbar \\to 0$.

  10. Bulk diffusion of 1D exclusion process with bond disorder

    E-Print Network [OSTI]

    A. Faggionato

    2010-03-30T23:59:59.000Z

    Given a doubly infinite sequence of positive numbers {c_k: k in Z} satisfying a LLN with limit A, we consider the nearest-neighbor simple exclusion process on Z where c_k is the probability rate of jumps between k and k+1. If A is infinite we require an additional minor technical condition. By extending a method developed by K. Nagy, we show that the diffusively rescaled process has hydrodynamic behavior described by the heat equation with diffusion constant 1/A. In particular, the process has diffusive behavior for finite A and subdiffusive behavior for infinite A.

  11. Diffusive mesh relaxation in ALE finite element numerical simulations

    SciTech Connect (OSTI)

    Dube, E.I.

    1996-06-01T23:59:59.000Z

    The theory for a diffusive mesh relaxation algorithm is developed for use in three-dimensional Arbitary Lagrange/Eulerian (ALE) finite element simulation techniques. This mesh relaxer is derived by a variational principle for an unstructured 3D grid using finite elements, and incorporates hourglass controls in the numerical implementation. The diffusive coefficients are based on the geometric properties of the existing mesh, and are chosen so as to allow for a smooth grid that retains the general shape of the original mesh. The diffusive mesh relaxation algorithm is then applied to an ALE code system, and results from several test cases are discussed.

  12. E-Print Network 3.0 - acetylene jet diffusion Sample Search Results

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

    the case of acetylene, we can... before they escape by diffusion. Conse- quently, the heat generated in acetylene has the same spatial... times in acetylene be- fore diffusion...

  13. E-Print Network 3.0 - agar diffusion cytotoxicity Sample Search...

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

    diffusion cytotoxicity Search Powered by Explorit Topic List Advanced Search Sample search results for: agar diffusion cytotoxicity Page: << < 1 2 3 4 5 > >> 1 J. Embryol. exp....

  14. E-Print Network 3.0 - ambipolar diffusion coefficient Sample...

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

    Summary: incorporating ambipolar diffusion, sometimes called "ion-neutral friction". It is important to understand how... in which ambipolar diffusion is the dominant...

  15. E-Print Network 3.0 - au flux diffus Sample Search Results

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

    chauffage (Fig. l), le flux... lumineux diffus diminue au lieu d'augmenter. Temperature (OC) FIG. 1. -Etude du flux lumineux diffus par... ternaire perpendiculaire au...

  16. E-Print Network 3.0 - advanced diffusion model Sample Search...

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

    of Michigan Collection: Geosciences 2 Oxygen self-diffusion fast-paths'' in titanite single crystals and a general method for deconvolving self-diffusion Summary:...

  17. E-Print Network 3.0 - advanced stage diffuse Sample Search Results

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

    of Rochester Collection: Physics 95 Oxygen self-diffusion fast-paths'' in titanite single crystals and a general method for deconvolving self-diffusion Summary: Oxygen...

  18. E-Print Network 3.0 - advanced diffusion studies Sample Search...

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

    State University Collection: Chemistry 3 Oxygen self-diffusion fast-paths'' in titanite single crystals and a general method for deconvolving self-diffusion Summary: could...

  19. E-Print Network 3.0 - anomalous diffusion due Sample Search Results

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

    and Technology Collection: Mathematics 97 Oxygen self-diffusion fast-paths'' in titanite single crystals and a general method for deconvolving self-diffusion Summary: profile...

  20. The Department of Mechanical Engineering --Engineering Mechanics

    E-Print Network [OSTI]

    Endres. William J.

    undergraduate and graduate courses in thermodynamics, fuel cell systems, sustainable energy systems, and mechanical systems design. Dr. Ellis is the director of the Sustainable Energy Research Program in Virginia. Ellis has 25 years of experience in engineering, research, and education related to the development

  1. Mechanical Properties of Nanocrystal Supercrystals

    E-Print Network [OSTI]

    Tam, Enrico

    2010-01-01T23:59:59.000Z

    and Its Impact on Mechanical Properties. MacromoleculesO. L. ; Minor, A. M. , Mechanical annealing and source-Mechanical Properties of Nanocrystal Supercrystals Enrico

  2. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    Lin, Xi

    operating in microfluidic environment, which can dynamically diverge, collimate and focus surface plasmons in 2012, with a joint appointment in the Department of Mechanical & Industrial Engineering

  3. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    Research Center. Currently he is an Assistant Prof. in the Aerospace and Ocean Engineering DepartmentMechanical engineering Department Seminar Cornel Sultan Virginia Tech Design for Control

  4. Technology Partnering Mechanisms

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

    expand a business with INL technologies, or require business support our Technology Transfer team is available to discuss the following contractual mechanisms: Cooperative...

  5. A fluid mechanical explanation of dark matter

    E-Print Network [OSTI]

    Carl H. Gibson

    1999-04-22T23:59:59.000Z

    Matter in the universe has become ``dark'' or ``missing'' through misconceptions about the fluid mechanics of gravitational structure formation. Gravitational condensation occurs on non-acoustic density nuclei at the largest Schwarz length scale L_{ST}, L_{SV}, L_{SM}, L_{SD} permitted by turbulence, viscous, or magnetic forces, or by the fluid diffusivity. Non-baryonic fluids have diffusivities larger (by factors of trillions or more) than baryonic (ordinary) fluids, and cannot condense to nucleate baryonic galaxy formation as is usually assumed. Baryonic fluids begin to condense in the plasma epoch at about 13,000 years after the big bang to form proto-superclusters, and form proto-galaxies by 300,000 years when the cooling plasma becomes neutral gas. Condensation occurs at small planetary masses to form ``primordial fog particles'' from nearly all of the primordial gas by the new theory, Gibson (1996), supporting the Schild (1996) conclusion from quasar Q0957+651A,B microlensing observations that the mass of the lens galaxy is dominated by ``rogue planets ... likely to be the missing mass''. Non-baryonic dark matter condenses on superclusters at scale L_{SD} to form massive super-halos.

  6. Uniform Diffusion of Acetonitrile inside Carbon Nanotubes Favors

    E-Print Network [OSTI]

    materials. Nanoporous carbon exhibits excellent charge-discharge properties and a stable cyclic life. Moreover, activated composite carbon films generate high specific capacitance, laying the foundationUniform Diffusion of Acetonitrile inside Carbon Nanotubes Favors Supercapacitor Performance Oleg N

  7. Modelling of monovacancy diffusion in W over wide temperature range

    SciTech Connect (OSTI)

    Bukonte, L., E-mail: laura.bukonte@helsinki.fi; Ahlgren, T.; Heinola, K. [Department of Physics, University of Helsinki, P.O. Box 43, 00014 Helsinki (Finland)

    2014-03-28T23:59:59.000Z

    The diffusion of monovacancies in tungsten is studied computationally over a wide temperature range from 1300?K until the melting point of the material. Our modelling is based on Molecular Dynamics technique and Density Functional Theory. The monovacancy migration barriers are calculated using nudged elastic band method for nearest and next-nearest neighbour monovacancy jumps. The diffusion pre-exponential factor for monovacancy diffusion is found to be two to three orders of magnitude higher than commonly used in computational studies, resulting in attempt frequency of the order 10{sup 15} Hz. Multiple nearest neighbour jumps of monovacancy are found to play an important role in the contribution to the total diffusion coefficient, especially at temperatures above 2/3 of T{sub m}, resulting in an upward curvature of the Arrhenius diagram. The probabilities for different nearest neighbour jumps for monovacancy in W are calculated at different temperatures.

  8. Perpendicular Diffusion of Energetic Particles in Collisionless Plasmas

    E-Print Network [OSTI]

    Shalchi, Andreas

    2015-01-01T23:59:59.000Z

    A fundamental problem in plasma and astrophysics is the interaction between energetic particles and magnetized plasmas. In the current paper we focus on particle diffusion across the guide magnetic field. It is shown that the perpendicular diffusion coefficient depends only on the parallel diffusion coefficient and the Kubo number. Therefore, one can find four asymptotic limits depending on the values of these two parameters. These regimes are the quasilinear limit, the Kadomtsev & Pogutse limit, the scaling of Rechester & Rosenbluth, and the scaling found by Zybin & Istomin. In the current article we focus on the Rechester & Rosenbluth scenario because this was not discovered before in the context of collisionless plasmas. Examples and applications are discussed as well. We show that an energy independent ratio of perpendicular and parallel diffusion coefficients can be found and that this ratio can be very small but also close to unity. This is exactly what one observes in the solar wind.

  9. Uranium(VI) Diffusion in Low-Permeability Subsurface Materials...

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

    Abstract: Uranium(VI) diffusion was investigated in a fine-grained saprolite sediment that was collected from U.S. Department of Energy (DOE) Oak Ridge site, TN, where...

  10. Three essays on the development and diffusion of pharmaceutical innovations

    E-Print Network [OSTI]

    Azoulay, Pierre

    2001-01-01T23:59:59.000Z

    The thesis comprises three essays on various aspects of the development and diffusion of pharmaceutical innovations, woven together by the idea that the production of clinical knowl- edge influences organizational design, ...

  11. Research paper Drug diffusion and binding in ionizable interpenetrating networks

    E-Print Network [OSTI]

    Peppas, Nicholas A.

    Research paper Drug diffusion and binding in ionizable interpenetrating networks from poly) (PVA), poly(acrylic acid) (PAA), and their interpenetrating networks (IPNs) were prepared using by measuring their equilibrium polymer volume fraction, equilibrium swelling ratio, and mesh size. Drug

  12. International diffusion practice : lessons from South Korea's New Village Movement

    E-Print Network [OSTI]

    Kim, Jung Hwa, M.C.P. Massachusetts Institute of Technology

    2013-01-01T23:59:59.000Z

    This research focuses on how South Korea's development model-namely, the Saemaul Undong, or the New Village Movement-is diffused internationally, in particular, to the developing country of Vietnam. South Korea's successful ...

  13. A Simulation Study of Diffusion in Microporous Materials

    E-Print Network [OSTI]

    Abouelnasr, Mahmoud Kamal Forrest

    2013-01-01T23:59:59.000Z

    of new zeolite-like materials. Phys. Chem. Chem. Phys. 13,screening of carbon-capture materials. Nat. Mater. 11, 633–Diffusion in nanoporous materials. (Wiley- VCH, 2012). 48.

  14. Pre-plated reactive diffusion-bonded battery electrode plaques

    DOE Patents [OSTI]

    Maskalick, Nicholas J. (Pittsburgh, PA)

    1984-01-01T23:59:59.000Z

    A high strength, metallic fiber battery plaque is made using reactive diffusion bonding techniques, where a substantial amount of the fibers are bonded together by an iron-nickel alloy.

  15. Big Data Projects on Solar Tech Evolution and Diffusion

    Broader source: Energy.gov [DOE]

    This is the meeting agenda from the Big Data Projects on Solar Technology Evolution and Diffusion kickoff meeting, held on July 15, 2013 in Arlington, VA and facilitated by the SunShot Initiative.

  16. apparent diffusion coefficient: Topics by E-print Network

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

    4 sites). We exploit the dependence of the diffusion coefficient on the system size Yeh and Hummer, J. Phys. Chem. B 108, 15873 (2004) to obtain the size-independent...

  17. apparent diffusion coefficients: Topics by E-print Network

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

    4 sites). We exploit the dependence of the diffusion coefficient on the system size Yeh and Hummer, J. Phys. Chem. B 108, 15873 (2004) to obtain the size-independent...

  18. auto diffusion function: Topics by E-print Network

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

    angle of 30mathrm o are investigated. The analysis reveals that the influ... Sun, Y 2005-01-01 3 Etude par diffusion de Huang des auto-interstitiels dans un alliage...

  19. Diffusion driven object propulsion in density stratified fluids

    E-Print Network [OSTI]

    Lenahan, Conor (Conor P.)

    2009-01-01T23:59:59.000Z

    An experimental study was conducted in order to verify the appropriateness of a two dimensional model of the flow creating diffusion driven object propulsion in density stratified fluids. Initial flow field experiments ...

  20. Optical processing furnace with quartz muffle and diffuser plate

    DOE Patents [OSTI]

    Sopori, B.L.

    1996-11-19T23:59:59.000Z

    An optical furnace for annealing a process wafer is disclosed comprising a source of optical energy, a quartz muffle having a door to hold the wafer for processing, and a quartz diffuser plate to diffuse the light impinging on the quartz muffle; a feedback system with a light sensor located in the wall of the muffle is also provided for controlling the source of optical energy. 5 figs.

  1. Algorithm for anisotropic diffusion in hydrogen-bonded networks

    E-Print Network [OSTI]

    Edoardo Milotti

    2007-04-04T23:59:59.000Z

    In this paper I describe a specialized algorithm for anisotropic diffusion determined by a field of transition rates. The algorithm can be used to describe some interesting forms of diffusion that occur in the study of proton motion in a network of hydrogen bonds. The algorithm produces data that require a nonstandard method of spectral analysis which is also developed here. Finally, I apply the algorithm to a simple specific example.

  2. Classical phase diffusion in small hysteretic Josephson junctions

    SciTech Connect (OSTI)

    Martinis, J.M.; Kautz, R.L. (National Institute of Standards and Technology, Boulder, Colorado 80303 (US))

    1989-10-02T23:59:59.000Z

    The existence of classical phase diffusion in hysteretic junctions is demonstrated by quantitative agreement between experimental and simulated {ital I}-{ital V} curves. The simulations are based on a circuit that accurately models both the junction and its external shunting impedance at microwave frequencies. We show that the bias current at which the junction switches from the phase diffusion state to the voltage state is sensitive to dissipation at microwave frequencies.

  3. Growth strains and creep in thermally grown alumina : oxide growth mechanisms.

    SciTech Connect (OSTI)

    Veal, B. W.; Paulikas, A. P.; Materials Science Division

    2008-01-01T23:59:59.000Z

    In situ measurements of growth strains and creep relaxation in {alpha}-Al{sub 2}O{sub 3} films, isothermally grown on {beta}-NiAl alloys at 1100 C, are reported and analyzed. Samples containing the reactive element Zr, and Zr-free samples, are examined. For Zr-free samples, steady state growth strains are compressive, whereas the growth strains are tensile when the reactive element (RE) is added to the alloy. This behavior is attributed to the counterflow of oxygen and aluminum interstitials, and to simultaneous counterflow of oxygen and aluminum vacancies, all moving through the grain boundaries. Cross diffusing oxygen and aluminum interstitials may merge and combine within the film, forming new oxide along grain boundary walls, a mechanism that leads to an in-plane compressive stress. Cross diffusing oxygen and aluminum vacancies will also merge and combine within the film; in this case material is removed from grain boundary walls, a mechanism that leads to an in-plane tensile stress. When no RE is present, the interstitial mechanism dominates and the resultant stress is compressive. Consistent with the 'dynamic segregation model', the RE slows the outdiffusion of Al interstitials permitting the tensile mechanism to dominate. This interpretation invokes the unconventional view that oxygen and aluminum interstitials and vacancies, created in and driven by the strong chemical gradient, all participate meaningfully in the scale growth process. Grain boundary diffusion measurements were obtained from low stress creep data, interpreted using the Coble model of grain boundary diffusion. Reported diffusion measurements of oxygen through grain boundaries of {alpha}-Al{sub 2}O{sub 3}, which are known to be inconsistent with oxide scale growth, are critically examined. A simple picture, a 'balanced defect model', emerges that is consistent with the dynamic segregation model, observed growth stresses and their dependence on the presence of a reactive element, sequential oxidation experiments, and our best knowledge about grain boundary diffusion coefficients.

  4. Boston University Department of Mechanical Engineering ME 303 Fluid Mechanics

    E-Print Network [OSTI]

    Boston University Department of Mechanical Engineering ME 303 ­ Fluid Mechanics Fall 2011 Class: EK301 Engineering Mechanics Course Textbook: Fundamentals of Fluid Mechanics, 6th ed., Munson B. Reference Texts: Fluid Mechanics, Landau and Lifshitz, Vol. 6 Fluid Mechanics, Y. Cengel and J. Cimbala

  5. CO diffusion into amorphous H2O ices

    E-Print Network [OSTI]

    Lauck, Trish; Shulenberger, Katherine; Rajappan, Mahesh; Oberg, Karin I; Cuppen, Herma M

    2015-01-01T23:59:59.000Z

    The mobility of atoms, molecules and radicals in icy grain mantles regulate ice restructuring, desorption, and chemistry in astrophysical environments. Interstellar ices are dominated by H2O, and diffusion on external and internal (pore) surfaces of H2O-rich ices is therefore a key process to constrain. This study aims to quantify the diffusion kinetics and barrier of the abundant ice constituent CO into H2O dominated ices at low temperatures (15-23 K), by measuring the mixing rate of initially layered H2O(:CO2)/CO ices. The mixed fraction of CO as a function of time is determined by monitoring the shape of the infrared CO stretching band. Mixing is observed at all investigated temperatures on minute time scales, and can be ascribed to CO diffusion in H2O ice pores. The diffusion coefficient and final mixed fraction depend on ice temperature, porosity, thickness and composition. The experiments are analyzed by applying Fick's diffusion equation under the assumption that mixing is due to CO diffusion into an i...

  6. Microscopic thermal diffusivity mapping using an infrared camera

    SciTech Connect (OSTI)

    Wang, H.; Dinwiddie, R.B.

    1997-12-31T23:59:59.000Z

    Standard flash thermal diffusivity measurements utilize a single-point infrared detector to measure the average temperature rise of the sample surface after a heat pulse. The averaging of infrared radiation over the sample surface could smear out the microscopic thermal diffusivity variations in some specimens, especially in fiber-reinforced composite materials. A high-speed, high-sensitivity infrared camera was employed in this study of composite materials. With a special microscope attachment, the spatial resolution of the camera can reach 5.4 {micro}m. The images can then be processed to generate microscopic thermal diffusivity maps of the material. SRM 1462 stainless steel was tested to evaluate the accuracy of the system. Thermal diffusivity micrographs of carbon-carbon composites and SCS-6/borosilicate glass were generated. Thermal diffusivity values of the carbon fiber bundles parallel to the heat flow were found to be higher than the matrix material. A thermal coupling effect between SCS-6 fiber and matrix was observed. The thermal coupling and measured thermal diffusivity value of the fiber were also dependent upon the thickness of the specimen.

  7. Mechanics of Electrodes in Lithium-ion Batteries A dissertation presented

    E-Print Network [OSTI]

    investigates the mechanical behavior of electrodes in Li-ion batteries. Each electrode in a Li-ion battery of electrodes in Li-ion batteries. We model an inelastic host of Li by considering diffusion, elastic reaction promotes plastic deformation by lowering the stress needed to flow. Li-ion battery is an emerging

  8. Journal of the Mechanics and Physics of Solids 54 (2006) 887903

    E-Print Network [OSTI]

    from prior work that OSG is sensitive to subcritical crack growth as water molecules in the environment make the material susceptible to subcritical crack growth when water is present in the environmentJournal of the Mechanics and Physics of Solids 54 (2006) 887­903 The effect of water diffusion

  9. Department of Mechanical Engineering

    E-Print Network [OSTI]

    Srivastava, Kumar Vaibhav

    Explore and understand applicable science Create new materials #12;Indian Railways #12;Wheel Impact Load automated system for On-Line estimation of Wheel Impact Loads and detection of Wheel Flats of running trains Detection System (WILD) #12;Derailment Mechanism Laboratory Tests Lab Brake Mechanism Placement of Sensors

  10. Mechanical & Aerospace Engineering

    E-Print Network [OSTI]

    Mechanical & Aerospace Engineering In the pursuit of developing manned, reusable hypersonic & Energy Arizona State University November 9, 2012 at 1:30pm in SCOB 228 School for Engineering of Matter will experience thermal and mechanical loads. The research presented will discuss advancements in structural

  11. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    Lin, Xi

    Mechanical engineering Department Seminar Junjie Niu Postdoctoral Associate MIT Engineering Nano nanomaterials in applications of energy storage, biomedicine and chemo-mechanics. In 2007, Dr.Niu received young-structured Materials for Energy Storage 11:00 AM Friday, 14 February 2014 Room 245, 110 Cummington Mall Refreshments

  12. Mechanical & Aerospace Engineering

    E-Print Network [OSTI]

    Mechanical & Aerospace Engineering The development of high-energy storage devices has been one energy capacity over 500 cycles. Teng Ma received his BS degree in Thermal and Power Engineering from Xi and Technology of China in 2009. He is currently a Ph.D. candidate in Mechanical Engineering at School

  13. Mechanical & Aerospace Engineering

    E-Print Network [OSTI]

    , and nuclear energy. She is a member of the American Society of Mechanical Engineers (ASME), Fluids EngineeringMechanical & Aerospace Engineering Interfacial flows are multi-material flows comprised of two of the interface between the fluids and the interface physics (like surface tension) needs to be predicted as part

  14. Respiratory Mechanisms of Support

    E-Print Network [OSTI]

    Kay, Mark A.

    Respiratory Mechanisms of Support Nasal Cannula Hi Flow Nasal Cannula CPAP Continuous positive the respiratory system is working to compensate for a metabolic issue so as to normalize the blood pH. HCO3 - 22 uses PIP Mechanical Ventilation: Volume vs. Pressure: Volume Control Pressure Control Cycle Volume Time

  15. Graduate Studies Environmental Fluid Mechanics

    E-Print Network [OSTI]

    Jacobs, Laurence J.

    Graduate Studies Environmental Fluid Mechanics and Water Resources Engineering ENVIRONMENTAL FLUID MECHANICS AND WATER RESOURCES ENGINEERING (EFMWR) The environmental fluid mechanics and water resources Environmental Fluid Mechanics and Hydraulic Engineering research focuses on turbulent entrainment, transport

  16. MECHANICAL ENGINEERING Program of Study

    E-Print Network [OSTI]

    Thomas, Andrew

    MECHANICAL ENGINEERING Program of Study Correspondence The Department of Mechanical Engineering offers graduate programs in the fields of thermal science and engineering mechanics. Current areas of research activity include Biomedical Engineering, Biomimetics, Composite Materials, Computational Mechanics

  17. Integrated Mechanical & Electrical Engineering (IMEE)

    E-Print Network [OSTI]

    Burton, Geoffrey R.

    Integrated Mechanical & Electrical Engineering (IMEE) Department of Electronic & Electrical Engineering and Department of Mechanical Engineering #12;Graduates able to work in both mechanical of Mechanical Engineers (IMechE) n Develop essential engineering skills through extensive project work n Enhance

  18. Mechanical code comparator

    DOE Patents [OSTI]

    Peter, Frank J. (Albuquerque, NM); Dalton, Larry J. (Bernalillo, NM); Plummer, David W. (Albuquerque, NM)

    2002-01-01T23:59:59.000Z

    A new class of mechanical code comparators is described which have broad potential for application in safety, surety, and security applications. These devices can be implemented as micro-scale electromechanical systems that isolate a secure or otherwise controlled device until an access code is entered. This access code is converted into a series of mechanical inputs to the mechanical code comparator, which compares the access code to a pre-input combination, entered previously into the mechanical code comparator by an operator at the system security control point. These devices provide extremely high levels of robust security. Being totally mechanical in operation, an access control system properly based on such devices cannot be circumvented by software attack alone.

  19. Graduate Studies Environmental Fluid Mechanics

    E-Print Network [OSTI]

    Storici, Francesca

    Graduate Studies Environmental Fluid Mechanics and Water Resources Engineering GRADUATE COURSESResourcesManagement · IntermediateFluidMechanics · AdvancedFluidMechanics · EnvironmentalFluidMechanics · AdvancedEnvironmental FluidMechanics · FluidMechanicsofOrganisms · OpenChannelHydraulics · SedimentTransport · ComputationalFluidMechanics

  20. Thermal-wave resonator cavity design and measurements of the thermal diffusivity of liquids

    E-Print Network [OSTI]

    Mandelis, Andreas

    Thermal-wave resonator cavity design and measurements of the thermal diffusivity of liquids J. A for the measurement of the thermal diffusivity of liquids. The thermal diffusivities of distilled water, glycerol the thermal diffusivity of gases, particularly air,8,9 and vapors10 to a high degree of precision. Although

  1. Diffusion and magnetic relaxation in model porous media Aniket Bhattacharya and S. D. Mahanti

    E-Print Network [OSTI]

    Bhattacharya, Aniket

    -dimensional analogs resemble commercially prepared Vycors and aerogels. When diffusion rates are compared for two

  2. Chapter 4. Permeability, Diffusivity, and Solubility of Gas and Solute Through Polymers

    E-Print Network [OSTI]

    unknown authors

    The diffusion of small molecules into polymers is a function of both the polymer and the diffusant. Factors which influence diffusion include: (1) the molecular size and physical state of the diffusant; (2) the morphology of the polymer; (3) the compatibility or solubility limit of the solute within the polymer matrix; (4) the volatility of the solute; (5) and the surface or interfacial

  3. ARM: SIRS: derived, correction of downwelling shortwave diffuse hemispheric measurements using Dutton and full algorithm

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Stoffel, Tom; Kay, Bev; Habte, Aron; Anderberg, Mary; Kutchenreiter, Mark

    SIRS: derived, correction of downwelling shortwave diffuse hemispheric measurements using Dutton and full algorithm

  4. NUMERICAL CALCULATIONS FOR THE ASYMPTOTIC, DIFFUSION DOMINATED MASS-TRANSFER COEFFICIENT IN PACKED BED REACTORS

    E-Print Network [OSTI]

    Fedkiw, Peter

    2011-01-01T23:59:59.000Z

    Calculations for the Asymptotic, Diffusion Dominated Mass-Transfer Coefficient in Packed Bed Reactors

  5. Rotary mechanical latch

    DOE Patents [OSTI]

    Spletzer, Barry L.; Martinez, Michael A.; Marron, Lisa C.

    2012-11-13T23:59:59.000Z

    A rotary mechanical latch for positive latching and unlatching of a rotary device with a latchable rotating assembly having a latching gear that can be driven to latched and unlatched states by a drive mechanism such as an electric motor. A cam arm affixed to the latching gear interfaces with leading and trailing latch cams affixed to a flange within the drive mechanism. The interaction of the cam arm with leading and trailing latch cams prevents rotation of the rotating assembly by external forces such as those due to vibration or tampering.

  6. Electronic door locking mechanism

    DOE Patents [OSTI]

    Williams, Gary Lin (428 E. Third Ave., Kennewick, WA 99336); Kirby, Patrick Gerald (1010 W. Fifteenth Pl., Kennewick, WA 99337)

    1997-01-01T23:59:59.000Z

    The invention is a motorized linkage for engaging a thumb piece in a door mechanism. The device has an exterior lock assembly with a small battery cell and combination lock. Proper entry by a user of a security code allows the battery to operate a small motor within the exterior lock assembly. The small motor manipulates a cam-plunger which moves an actuator pin into a thumb piece. The user applies a force on to the thumb piece. This force is transmitted by the thumb piece to a latch engagement mechanism by the actuator pin. The latch engagement mechanism operates the door latch.

  7. Electronic door locking mechanism

    DOE Patents [OSTI]

    Williams, G.L.; Kirby, P.G.

    1997-10-21T23:59:59.000Z

    The invention is a motorized linkage for engaging a thumb piece in a door mechanism. The device has an exterior lock assembly with a small battery cell and combination lock. Proper entry by a user of a security code allows the battery to operate a small motor within the exterior lock assembly. The small motor manipulates a cam-plunger which moves an actuator pin into a thumb piece. The user applies a force on to the thumb piece. This force is transmitted by the thumb piece to a latch engagement mechanism by the actuator pin. The latch engagement mechanism operates the door latch. 6 figs.

  8. Diffusion of Small He Clusters in Bulk and Grain Boundaries in ?-Fe

    SciTech Connect (OSTI)

    Deng, Huiqiu; Hu, W. Y.; Gao, Fei; Heinisch, Howard L.; Hu, Shenyang Y.; Li, Yulan; Kurtz, Richard J.

    2013-11-02T23:59:59.000Z

    The diffusion properties of He interstitials and He clusters in the bulk and grain boundaries (GBs) of ?-Fe have been studied using molecular dynamics with a newly developed Fe?He potential. The low migration energy barrier for a single He interstitial in the bulk is consistent with that obtained using ab initio methods. Small He clusters can migrate at low temperatures, but at higher temperatures they will kick out a self-interstitial atom (SIA) and become trapped by the vacancy, forming an He-vacancy complex. It is of great interest to note that small Henvacancy clusters (n<5) in the bulk are able to absorb an SIA, and the clusters become mobile again. Trapping and de-trapping of He clusters by emitting and absorbing an SIA represent an important dynamic process that provides a mechanism for the diffusion of He clusters and the nucleation of He bubbles in bulk Fe, particularly under irradiation in which numerous SIAs and vacancies are constantly being produced. A single He interstitial can migrate one-dimensionally or two-dimensionally within GBs, depending on the GB structure. Small interstitial Hen clusters 2 (n ~ 1 - 10) can easily kick out an SIA, and become trapped by the vacancy, while the SIA quickly diffuses away from the clusters, disappearing into the GB, such that de-trapping of the He clusters by absorbing an SIA is less likely to occur. This suggests that small He clusters may be treated as relatively immobile defects in GBs. The different behavior of He clusters in the bulk compared to their behavior in GBs may explain the different He bubble sizes experimentally observed in the bulk and in GBs in reduced activation ferritic/martensitic steels that have been simultaneously neutron irradiated and He implanted.

  9. Ultralight, ultrastiff mechanical metamaterials

    E-Print Network [OSTI]

    Zheng, Xiaoyu

    The mechanical properties of ordinary materials degrade substantially with reduced density because their structural elements bend under applied load. We report a class of microarchitected materials that maintain a nearly ...

  10. Mechanical engineering Department Seminar

    E-Print Network [OSTI]

    people trained from both perspectives can result in innovative solutions. At Fraunhofer CMI ­ coMechanical engineering Department Seminar Alexis Sauer-Budge Senior Research Scientist, Fraunhofer CMI Adjunct Research Assistant Professor, BME, Boston University Innovations at the intersection

  11. Mechanical & Aerospace Engineering

    E-Print Network [OSTI]

    Mechanical & Aerospace Engineering This presentation will address the development and transition of advanced structural health management (SHM) technologies from the perspective of understanding and the importance of understanding this role to increase the likelihood for transition of new technologies

  12. Diffusive parameters of tritiated water and uranium in chalk

    SciTech Connect (OSTI)

    Descostes, M. [CEA, DEN/DANS/DPC/SECR/Laboratory of Radionuclides Migration Measurements and Modelling, F-91191 Gif-sur-Yvette, (France); UMR 8587 CEA, Universite d'Evry, CNRS, (France); Pili, E. [CEA, DAM, DIF, F-91297 Arpajon, (France); Institut de Physique du Globe, Sorbonne Paris Cite, 1 rue Jussieu, 75238 Paris cedex 05, (France); Felix, O.; Frasca, B.; Radwan, J.; Juery, A. [CEA, DEN/DANS/DPC/SECR/Laboratory of Radionuclides Migration Measurements and Modelling, F-91191 Gif-sur-Yvette, (France)

    2012-07-15T23:59:59.000Z

    The Cretaceous Chalk of North-western Europe exhibits a double porosity (matrix and fracture) providing pathways for both slow and rapid flow of water. The present study aims at understanding and predicting the contaminant transfer properties through a significant section of this formation, with a particular emphasis on diffusion. This requires to study the nature of porosity and to perform diffusion experiments in representative samples using uranium and tritiated water (HTO), respectively taken as a reactive tracer and an inert one. The diffusive parameters, i.e. the accessible porosity and the effective diffusion coefficient were determined. Additional information was obtained with mercury porosimetry, gravimetric water content, textural and mineralogical characterization. The diffusion tests performed with HTO appear to be the best method to measure the total accessible porosity in any type of porous media, especially those having large pore size distributions. Our study demonstrates that classical gravimetric water content measurements are not sensitive to the reduction in pore size as opposed to HTO diffusion tests because capillary water is not extracted by conventional gravimetric method but can still be probed by diffusion experiments. We found effective diffusion coefficients D{sub e}(U(VI)) near 4 x 10{sup -10} m{sup 2}s{sup -1}). The slower migration of U(VI) compared to HTO indicates sorption, with R{sub d}(U(VI)) from 100 to 360 mL g{sup -1}. These values are one order of magnitude larger than other determinations of the U(VI) sorption coefficient because only the matrix porosity is concerned here. The migration of U(VI) in chalk is only limited by sorption on ancillary Fe-Pb-bearing minerals. Transport of HTO and U(VI) is independent of the porosity distribution. Uranium diffusion in the chalk matrix porosity is fast enough to allow the total invasion of the pore space within characteristic time scales of the order of 1000 years. This results in a partitioning of uranium velocities in fracture flow and matrix flow proportionally to the respective fracture and matrix porosities. (authors)

  13. Mechanical Compression Heat Pumps

    E-Print Network [OSTI]

    Apaloo, T. L.; Kawamura, K.; Matsuda, J.

    MECHANICAL COMPRESSION HEAT PUMPS Thomas-L. Apaloo and K. Kawamura Mycom Corporation, Los Angeles, California J. Matsuda, Mayekawa Mfg. Co., Tokyo, Japan ABSTRACT Mechanical compression heat pumping is not new in industrial applications.... In fact, industry history suggests that the theoretical concept was developed before 1825. Heat pump manufacturers gained the support of consultants and end-users when the energy crisis hit this country in 1973. That interest, today, has been...

  14. Test Program for High Efficiency Gas Turbine Exhaust Diffuser

    SciTech Connect (OSTI)

    Norris, Thomas R.

    2009-12-31T23:59:59.000Z

    This research relates to improving the efficiency of flow in a turbine exhaust, and thus, that of the turbine and power plant. The Phase I SBIR project demonstrated the technical viability of “strutlets” to control stalls on a model diffuser strut. Strutlets are a novel flow-improving vane concept intended to improve the efficiency of flow in turbine exhausts. Strutlets can help reduce turbine back pressure, and incrementally improve turbine efficiency, increase power, and reduce greenhouse gas emmission. The long-term goal is a 0.5 percent improvement of each item, averaged over the US gas turbine fleet. The strutlets were tested in a physical scale model of a gas turbine exhaust diffuser. The test flow passage is a straight, annular diffuser with three sets of struts. At the end of Phase 1, the ability of strutlets to keep flow attached to struts was demonstrated, but the strutlet drag was too high for a net efficiency advantage. An independently sponsored followup project did develop a highly-modified low-drag strutlet. In combination with other flow improving vanes, complicance to the stated goals was demonstrated for for simple cycle power plants, and to most of the goals for combined cycle power plants using this particular exhaust geometry. Importantly, low frequency diffuser noise was reduced by 5 dB or more, compared to the baseline. Appolicability to other diffuser geometries is yet to be demonstrated.

  15. Diffusion current in a system of coupled Josephson junctions

    SciTech Connect (OSTI)

    Shukrinov, Yu. M., E-mail: shukrinv@theor.jinr.ru; Rahmonov, I. R. [Joint Institute for Nuclear Research (Russian Federation)

    2012-08-15T23:59:59.000Z

    The role of a diffusion current in the phase dynamics of a system of coupled Josephson junctions (JJs) has been analyzed. It is shown that, by studying the temporal dependences of the superconducting, quasi-particle, diffusion, and displacement currents and the dependences of average values of these currents on the total current, it is possible to explain the main features of the current-voltage characteristic (CVC) of the system. The effect of a diffusion current on the character of CVC branching in the vicinity of a critical current and in the region of hysteresis, as well as on the part of CVC branch corresponding to a parametric resonance in the system is demonstrated. A clear interpretation of the differences in the character of CVC branching in a model of capacitively coupled JJs (CCJJ model) and a model of capacitive coupling with diffusion current (CCJJ+DC model) is proposed. It is shown that a decrease in the diffusion current in a JJ leads to the switching of this junction to an oscillating state. The results of model calculations are qualitatively consistent with the experimental data.

  16. Diffusivity anomaly in modified Stillinger-Weber liquids

    SciTech Connect (OSTI)

    Sengupta, Shiladitya [TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsingi, Hyderabad 500089 (India)] [TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsingi, Hyderabad 500089 (India); Vasisht, Vishwas V. [Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur Campus, Bangalore 560064 (India)] [Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur Campus, Bangalore 560064 (India); Sastry, Srikanth [TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsingi, Hyderabad 500089 (India) [TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsingi, Hyderabad 500089 (India); Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur Campus, Bangalore 560064 (India)

    2014-01-28T23:59:59.000Z

    By modifying the tetrahedrality (the strength of the three body interactions) in the well-known Stillinger-Weber model for silicon, we study the diffusivity of a series of model liquids as a function of tetrahedrality and temperature at fixed pressure. Previous work has shown that at constant temperature, the diffusivity exhibits a maximum as a function of tetrahedrality, which we refer to as the diffusivity anomaly, in analogy with the well-known anomaly in water upon variation of pressure at constant temperature. We explore to what extent the structural and thermodynamic changes accompanying changes in the interaction potential can help rationalize the diffusivity anomaly, by employing the Rosenfeld relation between diffusivity and the excess entropy (over the ideal gas reference value), and the pair correlation entropy, which provides an approximation to the excess entropy in terms of the pair correlation function. We find that in the modified Stillinger-Weber liquids, the Rosenfeld relation works well above the melting temperatures but exhibits deviations below, with the deviations becoming smaller for smaller tetrahedrality. Further we find that both the excess entropy and the pair correlation entropy at constant temperature go through maxima as a function of the tetrahedrality, thus demonstrating the close relationship between structural, thermodynamic, and dynamical anomalies in the modified Stillinger-Weber liquids.

  17. MECH 386 INDUSTRIAL FLUID MECHANICS INDUSTRIAL FLUID MECHANICS

    E-Print Network [OSTI]

    MECH 386 ­ INDUSTRIAL FLUID MECHANICS 1 INDUSTRIAL FLUID MECHANICS MECH 386 Contact information Dr This course is an introduction to industrial fluid mechanics. According to J. C. R. Hunt (a famous fluid mechanics specialist): "industrial fluid mechanics broadly covers those aspects of the design, manufacture

  18. Mechanical Engineering Is Mechanical Engineering right for me?

    E-Print Network [OSTI]

    Harman, Neal.A.

    Mechanical Engineering Is Mechanical Engineering right for me? If you are interested in the wide range of principles related to mechanical systems then Mechanical Engineering is well suited to you. A Mechanical Engineering degree programme will focus on aspects such as analysis, design, manufacture

  19. The Role of Micro-Mechanics in Soil Mechanics

    E-Print Network [OSTI]

    Bolton, Malcolm

    The Role of Micro-Mechanics in Soil Mechanics M.D.Bolton CUED/D-Soils/TR313 September 2000;1 The Role of Micro-Mechanics in Soil Mechanics Malcolm Bolton Summary It is suggested that observations of the changing microstructure of soils will permit the selection and refinement of relevant micro-mechanisms

  20. Fabrication of fine-grain tantalum diffusion barrier tube for Nb{sub 3}Sn conductors

    SciTech Connect (OSTI)

    Hartwig, K. T.; Balachandran, S.; Mezyenski, R.; Seymour, N. [Department of Mechanical Engineering, Texas A and M University, TX 77843 (United States); Robinson, J.; Barber, R. E. [Shear Form Inc, 207 Dellwood St, Bryan 77801 (United States)

    2014-01-27T23:59:59.000Z

    Diffusion barriers used in Nb{sub 3}Sn wire are often fabricated by wrapping Ta sheet into a tube with an overlap seam. A common result of such practice is non-uniform deformation in the Ta sheet as it thins by wire drawing because of non-uniform grain size and texture in the original Ta sheet. Seamless Ta tube with a fine-grain and uniform microstructure would be much better for the diffusion barrier application, but such material is expensive and difficult to manufacture. This report presents results on a new fabrication strategy for Ta tube that shows promise for manufacture of less costly tube with an improved microstructure. The fabrication method begins with seam-welded tube but gives a fine-grain uniform microstructure with little difference between the longitudinal seam weld region and the parent metal after post-weld processing. Severe plastic deformation processing (SPD) applied by area reduction extrusion and tube equal channel angular extrusion (tECAE) are used to refine and homogenize the microstructure. Microstructure and mechanical property results are presented for Ta tubes fabricated by this new processing strategy.

  1. Lévy Fluctuations and Tracer Diffusion in Dilute Suspensions of Algae and Bacteria

    E-Print Network [OSTI]

    Irwin M. Zaid; Jörn Dunkel; Julia M. Yeomans

    2010-09-20T23:59:59.000Z

    Swimming microorganisms rely on effective mixing strategies to achieve efficient nutrient influx. Recent experiments, probing the mixing capability of unicellular biflagellates, revealed that passive tracer particles exhibit anomalous non-Gaussian diffusion when immersed in a dilute suspension of self-motile Chlamydomonas reinhardtii algae. Qualitatively, this observation can be explained by the fact that the algae induce a fluid flow that may occasionally accelerate the colloidal tracers to relatively large velocities. A satisfactory quantitative theory of enhanced mixing in dilute active suspensions, however, is lacking at present. In particular, it is unclear how non-Gaussian signatures in the tracers' position distribution are linked to the self-propulsion mechanism of a microorganism. Here, we develop a systematic theoretical description of anomalous tracer diffusion in active suspensions, based on a simplified tracer-swimmer interaction model that captures the typical distance scaling of a microswimmer's flow field. We show that the experimentally observed non-Gaussian tails are generic and arise due to a combination of truncated L\\'evy statistics for the velocity field and algebraically decaying time correlations in the fluid. Our analytical considerations are illustrated through extensive simulations, implemented on graphics processing units to achieve the large sample sizes required for analyzing the tails of the tracer distributions.

  2. Effects of radiation on NO kinetics in turbulent hydrogen/air diffusion flames

    SciTech Connect (OSTI)

    Sivathanu, Y.R.; Gore, J.P.; Laurendeau, N.M.

    1997-07-01T23:59:59.000Z

    The authors describe a coupled radiation and NO kinetics calculation of turbulent hydrogen/air diffusion flame properties. Transport equations for mass, momentum, mixture fraction, enthalpy (sensible + chemical) including gas band radiation, and NO mass fraction are solved. NO kinetics is described by a one step thermal production mechanism. The local temperature is obtained by solving the enthalpy equation taking radiation loss from H{sub 2}O into consideration. Radiation/turbulence and chemical kinetics/turbulence interactions are treated using a clipped Gaussian probability density function (PDF) for the mixture fraction, and a delta PDF for the enthalpy. The source terms in the enthalpy and mass fraction of NO equations are treated using assumed PDF integration over the mixture fraction space. The results of the simulation are compared with existing measurements of the Emission Indices of NO (EINO) in turbulent H{sub 2}/air diffusion flames. The major conclusion of the paper is that coupled turbulence/radiation interactions should be taken into account while computing the EINO.

  3. Diffusive transport without detailed balance in motile bacteria: Does microbiology need statistical physics?

    E-Print Network [OSTI]

    M. E. Cates

    2012-08-20T23:59:59.000Z

    Microbiology is the science of microbes, particularly bacteria. Many bacteria are motile: they are capable of self-propulsion. Among these, a significant class execute so-called run-and-tumble motion: they follow a fairly straight path for a certain distance, then abruptly change direction before repeating the process. This dynamics has something in common with Brownian motion (it is diffusive at large scales), and also something in contrast. Specifically, motility parameters such as the run speed and tumble rate depend on the local environment and hence can vary in space. When they do so, even if a steady state is reached, this is not generally invariant under time-reversal: the principle of detailed balance, which restores the microscopic time-reversal symmetry of systems in thermal equilibrium, is mesoscopically absent in motile bacteria. This lack of detailed balance (allowed by the flux of chemical energy that drives motility) creates pitfalls for the unwary modeller. Here I review some statistical mechanical models for bacterial motility, presenting them as a paradigm for exploring diffusion without detailed balance. I also discuss the extent to which statistical physics is useful in understanding real or potential microbiological experiments.

  4. Diffuse emission of high-energy neutrinos from gamma-ray burst fireballs

    E-Print Network [OSTI]

    Tamborra, Irene

    2015-01-01T23:59:59.000Z

    Gamma-ray bursts (GRBs) have been suggested as possible sources of the high-energy neutrino flux recently detected by the IceCube telescope. We revisit the fireball emission model and elaborate an analytical prescription to estimate the high-energy neutrino prompt emission from pion and kaon decays, assuming that the leading mechanism for the neutrino production is lepto-hadronic. To this purpose, we include hadronic, radiative and adiabatic cooling effects and discuss their relevance for long- (including high- and low-luminosity) and short-duration GRBs. The expected diffuse neutrino background is derived, by requiring that the GRB high-energy neutrino counterparts follow up-to-date gamma-ray luminosity functions and redshift evolutions of the long and short GRBs. Although dedicated stacking searches have been unsuccessful up to now, we find that the GRBs could contribute up to a few percents to the observed IceCube high-energy neutrino flux for sub-PeV energies, assuming that the latter has a diffuse origin...

  5. Obsidians and tektites: Natural analogues for water diffusion in nuclear waste glasses

    SciTech Connect (OSTI)

    Mazer, J.J.; Bates, J.K.; Bradley, C.R. [Argonne National Lab., IL (United States); Stevenson, C.M. [Archaeological Services Consultants, Inc., Columbus, OH (United States)

    1991-11-01T23:59:59.000Z

    Projected scenarios for the proposed Yucca Mountain repository include significant periods of time when high relative humidity atmospheres will be present, thus the reaction processes of interest will include those known to occur under these conditions. The ideal natural analog for the proposed Yucca Mountain repository would consist of natural borosilicate glasses exposed to expected repository conditions for thousands of years; however, the prospects for identifying such an analog are remote, but an important caveat for using natural analog studies is to relate the reaction processes in the analog to those in the system of interest, rather than a strict comparison of the glass compositions. In lieu of this, identifying natural glasses that have reacted via reaction processes expected in the repository is the most attractive option. The goal of this study is to quantify molecular water diffusion in the natural analogs obsidian and tektites. Results from this study can be used in assessing the importance of factors affecting molecular water diffusion in nuclear waste glasses, relative to other identified reaction processes. In this way, a better understanding of the long-term reaction mechanism can be developed and incorporated into performance assessment models. 17 refs., 4 figs.

  6. Analysis and experimental study on formation conditions of large-scale barrier-free diffuse atmospheric pressure air plasmas in repetitive pulse mode

    SciTech Connect (OSTI)

    Li, Lee, E-mail: leeli@mail.hust.edu.cn; Liu, Lun; Liu, Yun-Long; Bin, Yu; Ge, Ya-Feng; Lin, Fo-Chang [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electric and Electronic Engineering, HuaZhong University of Science and Technology (HUST), Wuhan 430074 (China)

    2014-01-14T23:59:59.000Z

    Atmospheric air diffuse plasmas have enormous application potential in various fields of science and technology. Without dielectric barrier, generating large-scale air diffuse plasmas is always a challenging issue. This paper discusses and analyses the formation mechanism of cold homogenous plasma. It is proposed that generating stable diffuse atmospheric plasmas in open air should meet the three conditions: high transient power with low average power, excitation in low average E-field with locally high E-field region, and multiple overlapping electron avalanches. Accordingly, an experimental configuration of generating large-scale barrier-free diffuse air plasmas is designed. Based on runaway electron theory, a low duty-ratio, high voltage repetitive nanosecond pulse generator is chosen as a discharge excitation source. Using the wire-electrodes with small curvature radius, the gaps with highly non-uniform E-field are structured. Experimental results show that the volume-scaleable, barrier-free, homogeneous air non-thermal plasmas have been obtained between the gap spacing with the copper-wire electrodes. The area of air cold plasmas has been up to hundreds of square centimeters. The proposed formation conditions of large-scale barrier-free diffuse air plasmas are proved to be reasonable and feasible.

  7. Modeling the diffusion of Na+ in compacted water-saturated Na-bentonite as a function of pore water ionic strength

    SciTech Connect (OSTI)

    Bourg, I.C.; Sposito, G.; Bourg, A.C.M.

    2008-08-15T23:59:59.000Z

    Assessments of bentonite barrier performance in waste management scenarios require an accurate description of the diffusion of water and solutes through the barrier. A two-compartment macropore/nanopore model (on which smectite interlayer nanopores are treated as a distinct compartment of the overall pore space) was applied to describe the diffusion of {sup 22}Na{sup +} in compacted, water-saturated Na-bentonites and then compared with the well-known surface diffusion model. The two-compartment model successfully predicted the observed weak ionic strength dependence of the apparent diffusion coefficient (D{sub a}) of Na{sup +}, whereas the surface diffusion model did not, thus confirming previous research indicating the strong influence of interlayer nanopores on the properties of smectite clay barriers. Since bentonite mechanical properties and pore water chemistry have been described successfully with two-compartment models, the results in the present study represent an important contribution toward the construction of a comprehensive two-compartment model of compacted bentonite barriers.

  8. Curved and diffuse interface effects on the nuclear surface tension

    E-Print Network [OSTI]

    V. M. Kolomietz; S. V. Lukyanov; A. I. Sanzhur

    2012-01-30T23:59:59.000Z

    We redefine the surface tension coefficient for a nuclear Fermi-liquid drop with a finite diffuse layer. Following Gibbs-Tolman concept, we introduce the equimolar radius R_e of sharp surface droplet at which the surface tension is applied and the radius of tension surface R_s which provides the minimum of the surface tension coefficient \\sigma. This procedure allows us to derive both the surface tension and the corresponding curvature correction (Tolman length) correctly for the curved and diffuse interface. We point out that the curvature correction depends significantly on the finite diffuse interface. This fact is missed in traditional nuclear considerations of curvature correction to the surface tension. We show that Tolman's length \\xi is negative for nuclear Fermi-liquid drop. The value of the Tolman length is only slightly sensitive to the Skyrme force parametrization and equals \\xi=-0.36 fm.

  9. Diffusion Enhancement in Core-softened fluid confined in nanotubes

    E-Print Network [OSTI]

    José R. Bordin; Alan B. de Oliveira; Alexandre Diehl; Marcia C. Barbosa

    2012-08-05T23:59:59.000Z

    We study the effect of confinement in the dynamical behavior of a core-softened fluid. The fluid is modeled as a two length scales potential. This potential in the bulk reproduces the anomalous behavior observed in the density and in the diffusion of liquid water. A series of $NpT$ Molecular Dynamics simulations for this two length scales fluid confined in a nanotube were performed. We obtain that the diffusion coefficient increases with the increase of the nanotube radius for wide channels as expected for normal fluids. However, for narrow channels, the confinement shows an enhancement in the diffusion coefficient when the nanotube radius decreases. This behavior, observed for water, is explained in the framework of the two length scales potential.

  10. Phantom cascades: The effect of hidden nodes on information diffusion

    E-Print Network [OSTI]

    Belák, Václav; Sala, Alessandra; Morrison, Donn

    2015-01-01T23:59:59.000Z

    Research on information diffusion generally assumes complete knowledge of the underlying network. However, in the presence of factors such as increasing privacy awareness, restrictions on application programming interfaces (APIs) and sampling strategies, this assumption rarely holds in the real world which in turn leads to an underestimation of the size of information cascades. In this work we study the effect of hidden network structure on information diffusion processes. We characterise information cascades through activation paths traversing visible and hidden parts of the network. We quantify diffusion estimation error while varying the amount of hidden structure in five empirical and synthetic network datasets and demonstrate the effect of topological properties on this error. Finally, we suggest practical recommendations for practitioners and propose a model to predict the cascade size with minimal information regarding the underlying network.

  11. Particle production and nonlinear diffusion in relativistic systems

    E-Print Network [OSTI]

    Georg Wolschin

    2008-09-06T23:59:59.000Z

    The short parton production phase in high-energy heavy-ion collisions is treated analytically as a nonlinear diffusion process. The initial buildup of the rapidity density distributions of produced charged hadrons within tau_p = 0.25 fm/c occurs in three sources during the colored partonic phase. In a two-step approach, the subsequent diffusion in pseudorapidity space during the interaction time of tau_int = 7-10 fm/c (mean duration of the collision) is essentially linear as expressed in the Relativistic Diffusion Model (RDM) which yields excellent agreement with the data at RHIC energies, and allows for predictions at LHC energies. Results for d+Au are discussed in detail.

  12. Non-normality in combustion-acoustic interaction in diffusion flames: a critical revision

    E-Print Network [OSTI]

    Magri, Luca; Sujith, R I; Juniper, Matthew P

    2013-01-01T23:59:59.000Z

    Perturbations in a non-normal system can grow transiently even if the system is linearly stable. If this transient growth is sufficiently large, it can trigger self-sustained oscillations from small initial disturbances. This has important practical consequences for combustion-acoustic oscillations, which are a continual problem in rocket and aircraft engines. Balasubramanian and Sujith (Journal of Fluid Mechanics, 2008, 594, 29-57) modelled an infinite-rate chemistry diffusion flame in an acoustic duct and found that the transient growth in this system can amplify the initial energy by a factor, $G_{max}$, of order $10^5$ to $10^7$. However, recent investigations by L. Magri & M. P. Juniper have brought to light certain errors in that paper. When the errors are corrected, $G_{max}$ is found to be of order 1 to 10, revealing that non-normality is not as influential as it was thought to be.

  13. Evidence of Multi-Process Matrix Diffusion in a Single Fracturefrom a Field Tracer Test

    SciTech Connect (OSTI)

    Zhou, Quanlin; Liu, Hui-Hai; Bodvarsson, Gudmundur; Molz, Fred J.

    2005-06-11T23:59:59.000Z

    Compared to values inferred from laboratory tests on matrix cores, many field tracer tests in fractured rock have shown enhanced matrix diffusion coefficient values (obtained using a single-process matrix-diffusion model with a homogeneous matrix diffusion coefficient). To investigate this phenomenon, a conceptual model of multi-process matrix diffusion in a single-fracture system was developed. In this model, three matrix diffusion processes of different diffusion rates were assumed to coexist: (1) diffusion into stagnant water and infilling materials within fractures, (2) diffusion into a degraded matrix zone, and (3) further diffusion into an intact matrix zone. The validity of the conceptual model was then demonstrated by analyzing a unique tracer test conducted using a long-time constant-concentration injection. The tracer-test analysis was conducted using a numerical model capable of tracking the multiple matrix-diffusion processes. The analysis showed that in the degraded zone, a diffusion process with an enhanced diffusion rate controlled the steep rising limb and decay-like falling limb in the observed breakthrough curve, whereas in the intact matrix zone, a process involving a lower diffusion rate affected the long-term middle platform of slowly increasing tracer concentration. The different matrix-diffusion-coefficient values revealed from the field tracer test are consistent with the variability of matrix diffusion coefficient measured for rock cores with different degrees of fracture coating at the same site. By comparing to the matrix diffusion coefficient calibrated using single-process matrix diffusion, we demonstrated that this multi-process matrix diffusion may contribute to the enhanced matrix-diffusion-coefficient values for single-fracture systems at the field scale.

  14. Feasibility of gas-phase decontamination of gaseous diffusion equipment

    SciTech Connect (OSTI)

    Munday, E.B.; Simmons, D.W.

    1993-02-01T23:59:59.000Z

    The five buildings at the K-25 Site formerly involved in the gaseous diffusion process contain 5000 gaseous diffusion stages as well as support facilities that are internally contaminated with uranium deposits. The gaseous diffusion facilities located at the Portsmouth Gaseous Diffusion Plant and the Paducah Gaseous Diffusion Plant also contain similar equipment and will eventually close. The decontamination of these facilities will require the most cost-effective technology consistent with the criticality, health physics, industrial hygiene, and environmental concerns; the technology must keep exposures to hazardous substances to levels as low as reasonably achievable (ALARA). This report documents recent laboratory experiments that were conducted to determine the feasibility of gas-phase decontamination of the internal surfaces of the gaseous diffusion equipment that is contaminated with uranium deposits. A gaseous fluorinating agent is used to fluorinate the solid uranium deposits to gaseous uranium hexafluoride (UF{sub 6}), which can be recovered by chemical trapping or freezing. The lab results regarding the feasibility of the gas-phase process are encouraging. These results especially showed promise for a novel decontamination approach called the long-term, low-temperature (LTLT) process. In the LTLT process: The equipment is rendered leak tight, evacuated, leak tested, and pretreated, charged with chlorine trifluoride (ClF{sub 3}) to subatmospheric pressure, left for an extended period, possibly > 4 months, while processing other items. Then the UF{sub 6} and other gases are evacuated. The UF{sub 6} is recovered by chemical trapping. The lab results demonstrated that ClF{sub 3} gas at subatmospheric pressure and at {approx} 75{degree}F is capable of volatilizing heavy deposits of uranyl fluoride from copper metal surfaces sufficiently that the remaining radioactive emissions are below limits.

  15. Soot microstructure in steady and flickering laminar methane/air diffusion flames

    SciTech Connect (OSTI)

    Zhang, J.; Megaridis, C.M. [Univ. of Illinois, Chicago, IL (United States). Dept. of Mechanical Engineering

    1998-03-01T23:59:59.000Z

    An experimental investigation is presented to identify the mechanisms responsible for the enhanced sooting behavior of strongly flickering methane/air jet diffusion flames when compared to their steady counterparts. The work extends the implementation of thermophoretic sampling in flickering, co-flow, laminar, diffusion flames. Acoustic forcing of the fuel flow rate is used to phase lock the periodic flame flicker close to the natural flicker frequency ({approximately} 10 Hz for a burner diameter of {approximately} 1 cm). Soot primary sizes, determined as functions of flame coordinates, indicate that the largest soot primary units in strongly flickering methane/air flames are larger by {approximately} 60% than those measured in steady flames with the same mean reactant flow rates. The primary particle size measurements, when combined with the soot volume fractions reported by other investigators, indicate that soot surface areas in the flickering flame are three to four times larger than those under steady conditions. These results, along with the fact that residence times in the flickering flame are twice as long as those in the steady flame, suggest that specific soot surface growth rates under unsteady combustion conditions can be similar or even lower than those in the corresponding steady flames. Finally, the number of densities of soot primaries in flickering flames are found to be higher by 30--50% than those in steady flames, thus suggesting stronger and/or extended soot inception mechanisms under flickering conditions. The combination of longer flow residence times and greater population of incipient soot particles in flickering flames appears to be primarily responsible for the higher sooting propensity of methane under laminar unsteady combustion conditions.

  16. Falsification of dark energy by fluid mechanics

    E-Print Network [OSTI]

    Carl H. Gibson

    2012-03-23T23:59:59.000Z

    The 2011 Nobel Prize in Physics was awarded for the discovery of accelerating supernovae dimness, suggesting a remarkable change in the expansion rate of the Universe from a decrease since the big bang to an increase, driven by anti-gravity forces of a mysterious dark energy material comprising 70% of the Universe mass-energy. Fluid mechanical considerations falsify both the accelerating expansion and dark energy concepts. Kinematic viscosity is neglected in current standard models of self-gravitational structure formation, which rely on cold dark matter CDM condensations and clusterings that are also falsified by fluid mechanics. Weakly collisional CDM particles do not condense but diffuse away. Photon viscosity predicts superclustervoid fragmentation early in the plasma epoch and protogalaxies at the end. At the plasma-gas transition, the plasma fragments into Earth-mass gas planets in trillion planet clumps (proto-globular-star-cluster PGCs). The hydrogen planets freeze to form the dark matter of galaxies and merge to form their stars. Dark energy is a systematic dimming error for Supernovae Ia caused by dark matter planets near hot white dwarf stars at the Chandrasekhar carbon limit. Evaporated planet atmospheres may or may not scatter light from the events depending on the line of sight.

  17. Current distribution in systems with anomalous diffusion: renormalisation group approach

    E-Print Network [OSTI]

    Vivien Lecomte; Uwe C. Tauber; Frederic van Wijland

    2007-02-01T23:59:59.000Z

    We investigate the asymptotic properties of the large deviation function of the integrated particle current in systems, in or out of thermal equilibrium, whose dynamics exhibits anomalous diffusion. The physical systems covered by our study include mutually repelling particles with a drift, a driven lattice gas displaying a continuous nonequilibrium phase transition, and particles diffusing in a anisotropic random advective field. It is exemplified how renormalisation group techniques allow for a systematic determination of power laws in the corresponding current large deviation functions. We show that the latter are governed by known universal scaling exponents, specifically, the anomalous dimension of the noise correlators.

  18. The Chern-Simons diffusion rate from higher curvature gravity

    E-Print Network [OSTI]

    Viktor Jahnke; Anderson Seigo Misobuchi; Diego Trancanelli

    2014-03-13T23:59:59.000Z

    An important transport coefficient in the study of non-Abelian plasmas is the Chern-Simons diffusion rate, which parameterizes the rate of transition among the degenerate vacua of a gauge theory. We compute this quantity at strong coupling, via holography, using two theories of gravity with higher curvature corrections, namely Gauss-Bonnet gravity and quasi-topological gravity. We find that these corrections may either increase or decrease the result obtained from Einstein's gravity, depending on the value of the couplings. The Chern-Simons diffusion rate for Gauss-Bonnet gravity decreases as the shear viscosity over entropy ratio is increased.

  19. Anomalous diffusion for inertial particles under gravity in parallel flows

    E-Print Network [OSTI]

    Marco Martins Afonso

    2014-07-04T23:59:59.000Z

    We investigate the bounds between normal or anomalous effective diffusion for inertial particles transported by parallel flows. The infrared behavior of the fluid kinetic-energy spectrum, i.e. the possible presence of long-range spatio-temporal correlations, is modeled as a power law by means of two parameters, and the problem is studied as a function of these latter. Our results, obtained in the limit of weak relative inertia, extend well-known results for tracers and apply to particles of any mass density, subject to gravity and Brownian diffusion. We consider both steady and time-dependent flows, and cases of both vanishing and finite particle sedimentation.

  20. Estimation of effective diffusion coefficients in porous catalysts

    E-Print Network [OSTI]

    Kulkarni, Shrikant Ulhas

    1991-01-01T23:59:59.000Z

    'usivities were obtained for diR'usion of toluene in zeolites LaZSM-5, FeZSM-5 and BZSM-5. The corrected difl'usivities obtained for the zeolites showed a, dependence on the concentrat1on of' adsorbed species. Uptake experiments were conducted f' or studying... diffusion of n- hexane in a type II crystalline titanate, and the intracrystalline diffusivities were found to be independent of the adsorbate concentration. sv ACKNOWLEDGEMENT I would like to acknowledge my research advisor, Dr. R. G. Anthony...

  1. Measuring the thermal diffusivity in a student laboratory

    E-Print Network [OSTI]

    Sparavigna, Amelia Carolina

    2012-01-01T23:59:59.000Z

    The paper describes a method for measuring the thermal diffusivity of materials having a high thermal conductivity. The apparatus is rather simple and low-cost, being therefore suitable in a laboratory for undergraduate students of engineering schools, where several set-ups are often required. A recurrence numerical approach solves the thermal field in the specimen, which is depending on the thermal diffusivity of its material. The numerical method requires the temperature data from two different positions in the specimen, measured by two thermocouples connected to a temperature logger.

  2. Two types of diffusions at the cathode/electrolyte interface in IT-SOFCs

    SciTech Connect (OSTI)

    Li Zhipeng, E-mail: LI.Zhipeng@nims.go.jp [Global Research Center for Environment and Energy based on Nanomaterials Science, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Mori, Toshiyuki [Global Research Center for Environment and Energy based on Nanomaterials Science, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Auchterlonie, Graeme John [Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, Queensland 4072 (Australia); Zou Jin [Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, Queensland 4072 (Australia); Division of Materials, University of Queensland, St. Lucia, Brisbane, Queensland 4072 (Australia); Drennan, John [Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, Queensland 4072 (Australia)

    2011-09-15T23:59:59.000Z

    Analytical transmission electron microscopy, in particular with the combination of energy dispersive X-ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS), has been performed to investigate the microstructure and microchemistry of the interfacial region between the cathode (La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3}, LSCF) and the electrolyte (Gd-doped ceria, GDC). Two types of diffusions, mutual diffusion between cathode and electrolyte as well as the diffusion along grain boundaries, have been clarified. These diffusions suggest that the chemical stability of LSCF and GDC are not as good as previously reported. The results are more noteworthy if we take into consideration the fact that such interdiffusions occur even during the sintering process of cell preparation. - Graphical Abstract: Two types of diffusions, the mutual diffusion and the diffusion along grain boundaries, occurred at the cathode/electrolyte interface of intermediate temperature solid state fuel cells, during cell preparation. The mutual diffusion is denoted by black arrows and the diffusion along grain boundaries assigned by pink arrows. Highlights: > All the cations in cathode (LSCF) and electrolyte (GDC) can mutually diffuse into each other. > Diffusing elements will segregate at grain boundaries or triple junctions around the cathode/electrolyte interface. > Two types of diffusions, the mutual diffusion and diffusion along grain boundaries, have been clarified thereafter.

  3. MECHANICAL ENGINEERING UNDERGRADUATE HONORS THESIS

    E-Print Network [OSTI]

    Prinz, Friedrich B.

    , when two bound copies are to be submitted to the Mechanical Engineering Services Office #12;PLEASE Mechanical Engineering Student Services: ¨ Application Approved ¨ Application Denied Signature of UGMECHANICAL ENGINEERING UNDERGRADUATE HONORS THESIS The Department of Mechanical Engineering

  4. STANFORD UNIVERSITY MECHANICAL ENGINEERING DEPARTMENT

    E-Print Network [OSTI]

    Prinz, Friedrich B.

    20062007 Mechanical Engineering Student Services Building 530, Room 125 (650) 7257695 FAX (650) 7234882STANFORD UNIVERSITY MECHANICAL ENGINEERING DEPARTMENT GRADUATE STUDENT HANDBOOK Academic Year Revised 9/06 #12;MECHANICAL ENGINEERING GRADUATE STUDENT HANDBOOK 20062007 TABLE OF CONTENTS (Clickable

  5. Experimental unsaturated soil mechanics

    E-Print Network [OSTI]

    Delage, Pierre

    2008-01-01T23:59:59.000Z

    In this general report, experimental systems and procedures of investigating the hydro-mechanical behaviour of unsaturated soils are presented. The water retention properties of unsaturated soils are commented and linked to various physical parameters and properties of the soils. Techniques of controlling suction are described together with their adaptation in various laboratory testing devices. Some typical features of the mechanical behaviour of unsaturated soils are presented within an elasto-plastic framework. An attempt to describe the numerous and significant recent advances in the investigation of the behaviour of unsaturated soils, including the contributions to this Conference, is proposed.

  6. Mechanical Behavior of Indium Nanostructures

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

    Mechanical Behavior of Indium Nanostructures Mechanical Behavior of Indium Nanostructures Print Wednesday, 26 May 2010 00:00 Indium is a key material in lead-free solder...

  7. Comprehensive mechanisms for combustion chemistry: Experiment, modeling, and sensitivity analysis

    SciTech Connect (OSTI)

    Dryer, F.L.; Yetter, R.A. [Princeton Univ., NJ (United States)

    1993-12-01T23:59:59.000Z

    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.

  8. Dependence of Turing pattern wavelength on diffusion rate

    SciTech Connect (OSTI)

    Ouyang, Q. (Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States)); Li, R.; Li, G. (Department of Chemistry, The Tsinghua University, Beijing 10008 (China)); Swinney, H.L. (Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States))

    1995-02-08T23:59:59.000Z

    The relation between the diffusion coefficient of reactants and the wavelength of Turing patterns is examined in experiments on the chlorite--iodide--malonic acid (CIMA) reaction in gel media. The diffusion coefficients in polyacrylamide and agarose gels are varied by varying the gel densities. The diffusion coefficient [ital D] of NaCl is found to vary from 0.5[times]10[sup [minus]5] to 1.8[times]10[sup [minus]5] cm[sup 2]/s for the gel conditions considered. The CIMA reactants are assumed to have diffusion coefficients that are directly proportional to that of NaCl. The wavelength [lambda] of the observed hexagonal patterns (0.13--0.28 mm) varies in accord with the predicted relation for Turing patterns, [lambda][similar to][ital D][sup 1/2]. Moreover, the predicted relationship to a characteristic period of oscillation [tau], [lambda]=(2[pi][tau][ital D])[sup 1/2], is supported by measurements of [tau] just beyond a Hopf bifurcation in a stirred flow reactor.

  9. Fuel cell entropy production with ohmic heating and diffusive polarization

    E-Print Network [OSTI]

    Naterer, Greg F.

    Fuel cell entropy production with ohmic heating and diffusive polarization G.F. Naterer a,*, C production of ohmic heating and concentration polarization is investigated for two types of fuel cells (PEMFC oxide fuel cell (SOFC), this article formulates entropy production within electrodes of a proton

  10. Geometry-induced asymmetric diffusion Robert S. Shaw*

    E-Print Network [OSTI]

    Texas at Austin. University of

    channels Asymmetric diffusion appears in studies of ion transport across membranes (1 that ions can pass through a membrane more readily in one direction than the other. We demonstrate here constraints may play a role in common biological contexts such as membrane ion channels. asymmetric pores

  11. Dynamic physiological modeling for functional diffuse optical tomography

    E-Print Network [OSTI]

    ,c and David A. Boasa a Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging and brain that reflect competing metabolic demands and cardiovascular dynamics. The diffuse nature of near- namic response. In this paper, we present a linear state-space model for DOT analysis that models

  12. Adaptive Energy Forecasting and Information Diffusion for Smart Power Grids

    E-Print Network [OSTI]

    Prasanna, Viktor K.

    1 Adaptive Energy Forecasting and Information Diffusion for Smart Power Grids Yogesh Simmhan, prasanna}@usc.edu I. INTRODUCTION Smart Power Grids exemplify an emerging class of Cyber Physical-on paradigm to support operational needs. Smart Grids are an outcome of instrumentation, such as Phasor

  13. Microstructural Evolution and interfacial motion in systems with diffusion barriers

    SciTech Connect (OSTI)

    Perry H. Leo

    2009-03-05T23:59:59.000Z

    This research program was designed to model and simulate phase transformations in systems containing diffusion barriers. The modeling work included mass flow, phase formation, and microstructural evolution in interdiffusing systems. Simulation work was done by developing Cahn-Hilliard and phase field equations governing both the temporal and spatial evolution of the composition and deformation fields and other important phase variables.

  14. Spiral wave dynamics: reaction and diffusion versus kinematics

    E-Print Network [OSTI]

    Fiedler, Bernold

    Spiral wave dynamics: reaction and diffusion versus kinematics B. Fiedler, M. Georgi, and N. Jangle of excitable media to explain the propagation of electrical excita- tion fronts in the heart. Waves of electrical activity in the heart muscle assist its rhythmic contractions. The presence of spiral waves can

  15. Numerical study on the validity of the diffusion approximation

    E-Print Network [OSTI]

    Virginia Tech

    of photons can be accurately modeled by the radiative transport equation (RTE).9,10 Because and the radiative transport as implemented by Monte Carlo simulation in the cases of point and ball sources. Our of the difficulties in handling the RTE directly, the diffusion approximation to the transport equation has been

  16. Generalized diffusion model in optical tomography with clear layers

    E-Print Network [OSTI]

    Ren, Kui

    transport equation that describes the den- sity of photons in the phase space, i.e., as a function of po increasingly often.9 For computational savings an approximation to radiative transport is often preferred solve phase-space transport equa- tions instead of the inaccurate diffusion equations.12,16 A large

  17. Inwardly Rotating Spiral Waves in a Reaction-Diffusion System

    E-Print Network [OSTI]

    Epstein, Irving R.

    are nonpolar, are produced in the water droplets and can diffuse into the oil phase. Communication between spirals found in the BZ system dispersed in water droplets of a water-in-oil microemulsion oscillatory BZ reaction in water-in-oil AOT microemulsion (BZ-AOT system) (16, 19, 20). This system consists

  18. Integration of Arsenic Trisulfide and Titanium Diffused Lithium Niobate Waveguides

    E-Print Network [OSTI]

    Solmaz, Mehmet E.

    2011-08-08T23:59:59.000Z

    A chalcogenide glass (arsenic-trisulfide, As2S3) optical waveguide is vertically integrated onto titanium-diffused lithium-niobate (Ti:LiNbO3) waveguides to add optical feedback paths and to create more compact optical circuits. Lithium...

  19. Application of Perona Malik anisotropic diffusion on digital radiographic image

    SciTech Connect (OSTI)

    Halim, Suhaila Abd; Razak, Rohayu Abdul; Ibrahim, Arsmah [Center of Mathematics Studies, Faculty of Computer and Mathematical Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor DE (Malaysia); Manurung, Yupiter HP [Advanced Manufacturing Technology Center, Faculty of Mechanical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor DE (Malaysia)

    2014-07-10T23:59:59.000Z

    Perona Malik Anisotropic Diffusion (PMAD) is a very useful and efficient denoising technique if the parameters are properly selected. Overestimating the parameters may cause oversmoothed and underestimating it may leave unfiltered noise. This makes the selection of parameters a crucial process. In this paper the PMAD model is solved using a finite difference scheme The discretized model is evaluated using different diffusion coefficient of exponential and quadratic on defective radiographic images in terms of quality and efficiency. In the application of the PMAD model on image data, a set of defective radiographic images of welding is used as input data. Peak Signal to Noise Ratio (PSNR), Structural Similarity Measure (SSIM) and temporal time are used to evaluate the performance of the model. The implementation of the experiment has been carried out using MATLAB R2009a. In terms of quality, results show that the Quadratic Diffusion Coefficient Function (QDCF) provides better results compared with the Exponential Diffusion Coefficient Function (EDCF). In conclusion, the denoising effect using PMAD model based on finite difference scheme shows able to improve image quality by removing noise in the defective radiographic image.

  20. Modelling precipitation of niobium carbide in austenite: multicomponent diffusion, capillarity,

    E-Print Network [OSTI]

    Cambridge, University of

    Modelling precipitation of niobium carbide in austenite: multicomponent diffusion, capillarity, and coarsening N. Fujita and H. K. D. H. Bhadeshia The growth of niobium carbide in austenite involves for the overall transformation kinetics of niobium carbide precipitation in austenite that takes into account

  1. Extending ballistic graphene FET lumped element models to diffusive devices

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Extending ballistic graphene FET lumped element models to diffusive devices G Vincenzi1,2 , G graphene field effect device model is presented. The model is based on the "Top-of-the-barrier" approach which is usually valid only for ballistic graphene nanotransistors. Proper modifications are introduced

  2. Modelling Electrical Car Diffusion Based on Agent Tao Zhang, 3

    E-Print Network [OSTI]

    Aickelin, Uwe

    the UK government's 2020 target of cutting emission. Figure 1. city energy consumption in UK, 2009 government announced a project that anyone who buys an electric plug-in car from 2011 will get a 25% discountModelling Electrical Car Diffusion Based on Agent 1 Lei Yu, ,2 Tao Zhang, 3 Siebers Peer-Ola, 4

  3. Inverse diffusion from knowledge of power densities Guillaume Bal

    E-Print Network [OSTI]

    Bal, Guillaume

    asymptotic expansions and (Fourier) transformation, this allow us to construct the power density) provides access to the power density H(x) = (x)|u|2 (x) for all x inside the domain of interestInverse diffusion from knowledge of power densities Guillaume Bal , Eric Bonnetier , Fran

  4. High phosphorous doped germanium: Dopant diffusion and modeling

    E-Print Network [OSTI]

    Cai, Yan

    The in situ n-type doping of Ge thin films epitaxial grown on Si substrates is limited to 1?×?10[superscript 19]?cm[superscript ?3] by the phosphorous out-diffusion during growth at 600?°C. By studying the phosphorous ...

  5. CHAPTER 1 INTRODUCTION 1.1 WHY DIFFUSION IN POLYMERS

    E-Print Network [OSTI]

    Goddard III, William A.

    .5. IMPLEMENTATION ON MACHINES THAT PROVIDE ONE-SIDED COMMUNICATION. 3.5 PERFORMANCE RESULTS 3.5.1 Performance on shared-memory architectures 3.5.2 Performance on message-passing architectures 3.6. PROGRAMMING INTERFACE OF THE RANDOM WALK TO ELECTRICALLY CHARGED PENETRANTS. CHAPTER 5 METHODS FOR STUDYING DIFFUSION IN POLYMERS: 5

  6. Diffusion in amorphous media Mihail S.Iotov

    E-Print Network [OSTI]

    Goddard III, William A.

    ON MACHINES THAT PROVIDE ONE-SIDED COMMUNICATION. 3.5 PERFORMANCE RESULTS 3.5.1 Performance on shared-memory architectures 3.5.2 Performance on message-passing architectures 3.6. PROGRAMMING INTERFACE DESCRIPTION TO ELECTRICALLY CHARGED PENETRANTS. CHAPTER 5 METHODS FOR STUDYING DIFFUSION IN POLYMERS: 5.1. PHENOMENOLOGICAL

  7. Low Mach Number Fluctuating Hydrodynamics of Diffusively Mixing Fluids

    E-Print Network [OSTI]

    A. Donev; A. J. Nonaka; Y. Sun; T. G. Fai; A. L. Garcia; J. B. Bell

    2014-04-29T23:59:59.000Z

    We formulate low Mach number fluctuating hydrodynamic equations appropriate for modeling diffusive mixing in isothermal mixtures of fluids with different density and transport coefficients. These equations eliminate the fluctuations in pressure associated with the propagation of sound waves by replacing the equation of state with a local thermodynamic constraint. We demonstrate that the low Mach number model preserves the spatio-temporal spectrum of the slower diffusive fluctuations. We develop a strictly conservative finite-volume spatial discretization of the low Mach number fluctuating equations in both two and three dimensions and construct several explicit Runge-Kutta temporal integrators that strictly maintain the equation of state constraint. The resulting spatio-temporal discretization is second-order accurate deterministically and maintains fluctuation-dissipation balance in the linearized stochastic equations. We apply our algorithms to model the development of giant concentration fluctuations in the presence of concentration gradients, and investigate the validity of common simplifications such as neglecting the spatial non-homogeneity of density and transport properties. We perform simulations of diffusive mixing of two fluids of different densities in two dimensions and compare the results of low Mach number continuum simulations to hard-disk molecular dynamics simulations. Excellent agreement is observed between the particle and continuum simulations of giant fluctuations during time-dependent diffusive mixing.

  8. Filing Holes in Complex Surfaces Using Volumetric Diffusion

    E-Print Network [OSTI]

    Kazhdan, Michael

    Method for Building Complex Models From range Images, '96) ­ Applies line of sight constraints based components ­ Complex hole geometry Construction of an arbitrary mesh can result in non-manifold surfaceFiling Holes in Complex Surfaces Using Volumetric Diffusion J. Davis, S. Marschner, M. Garr and M

  9. Self-similar and charged spheres in the diffusion approximation

    E-Print Network [OSTI]

    Barreto, W

    1999-01-01T23:59:59.000Z

    We study spherical, charged and self--similar distributions of matter in the diffusion approximation. We propose a simple, dynamic but physically meaningful solution. For such a solution we obtain a model in which the distribution becomes static and changes to dust. The collapse is halted with damped mass oscillations about the absolute value of the total charge.

  10. Does the photon-diffusion coefficient depend on absorption?

    E-Print Network [OSTI]

    Boas, David

    Does the photon-diffusion coefficient depend on absorption? T. Durduran and A. G. Yodh Department independent of absorption, i.e., D0 v/3 s . After presentation of the general theoretical arguments underlying this assertion, Monte Carlo simulations are performed and explicitly reveal that the absorption- independent

  11. Full-wavelet approach for fluorescence diffuse optical tomography

    E-Print Network [OSTI]

    Boyer, Edmond

    Full-wavelet approach for fluorescence diffuse optical tomography with structured illumination Leonardo da Vinci 32, I-20133 Milan, Italy 3 Centre for Medical Image Computing, University College London); published October 28, 2010 We present a fast reconstruction method for fluorescence optical tomography

  12. Skin cancer detection by oblique-incidence diffuse reflectance spectroscopy

    E-Print Network [OSTI]

    Smith, Elizabeth Brooks

    2009-05-15T23:59:59.000Z

    Skin cancer is the most common form of cancer and it is on the rise. If skin cancer is diagnosed early enough, the survival rate is close to 90%. Oblique-incidence diffuse reflectance (OIR) spectroscopy offers a technology that may be used...

  13. AN ANISOTROPIC DIFFUSION APPROACH FOR EARLY DETECTION OF BREAST CANCER

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    AN ANISOTROPIC DIFFUSION APPROACH FOR EARLY DETECTION OF BREAST CANCER Marius George LINGURARU, Oxford OX2 7BZ, United Kingdom mglin@robots.ox.ac.uk Abstract: The prevalence of breast cancer must provide effective clinical methods to detect cancer and improve life expectancy. Considerable

  14. Diffusive propagation of wave packets in a fluctuating periodic potential

    E-Print Network [OSTI]

    Eman Hamza; Yang Kang; Jeffrey Schenker

    2010-10-05T23:59:59.000Z

    We consider the evolution of a tight binding wave packet propagating in a fluctuating periodic potential. If the fluctuations stem from a stationary Markov process satisfying certain technical criteria, we show that the square amplitude of the wave packet after diffusive rescaling converges to a superposition of solutions of a heat equation.

  15. Graphene: From Diffusive to Ultraclean-Interacting Systems

    E-Print Network [OSTI]

    Amrhein, Valentin

    Graphene: From Diffusive to Ultraclean-Interacting Systems Inauguraldissertation zur Erlangung der. Introduction 1 2. The Properties of Graphene 3 2.1. Band Structure of Graphene . . . . . . . . . . . . . . . . . . . . . 3 2.1.1. Single Layer Graphene . . . . . . . . . . . . . . . . . . . . 3 2.1.2. Bilayer Graphene

  16. LE JOURNAL DE PHYSIQUE THORIE DU TRANAGE MAGNTIQUE DE DIFFUSION

    E-Print Network [OSTI]

    Boyer, Edmond

    LE JOURNAL DE PHYSIQUE ET LE RADIUM TH�ORIE DU TRA�NAGE MAGN�TIQUE DE DIFFUSION Par M. LOUIS N�EL. Laboratoire d'�lectrostatique et de Physique du Métal, Grenoble. Sommaire. - Après avoir rappelé l LE JOURNAL DE PHYSIQUE ILT

  17. DARK MATTER Tracing the "Cosmic Web" with Diffuse Gas

    E-Print Network [OSTI]

    Steidel, Chuck

    1 DARK MATTER STARS GAS NEUTRAL HYDROGEN Tracing the "Cosmic Web" with Diffuse Gas Quasar Quasar Absorption Lines Keck/HIRES Quasar Spectrum Observer baryons dark matter potential isotropic UV only on and the radiation field intensity... H I #12;5 GOAL: the primordial dark matter power spectrum

  18. Template-Based Tractography for Clinical Neonatal Diffusion Imaging Data

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Los Angeles, 4650 Sunset Blvd, Los Angeles-CA, USA; dParietal Research Team, INRIA Parc Orsay difficult to define structure by means of diffusion profiles. Here, we introduce a post-processing method to the difficulties associated to keeping a non-sedated neonate static into the scanner the desired time

  19. Department of Mechanical Engineering

    E-Print Network [OSTI]

    Li, Teng

    Department of Mechanical Engineering 2014 Fast Facts Faculty Based on 2013 statistics from Master's Degrees Awarded 45 Doctorate Degrees Awarded Funding Fiscal Year 2013 $20M Total Research for Energetic Concepts Development Center for Environmental Energy Engineering Center for Risk and Reliability

  20. MECHANICAL TEST LAB CAPABILITIES

    E-Print Network [OSTI]

    MECHANICAL TEST LAB CAPABILITIES · Static and cyclic testing (ASTM and non-standard) · Impact drop testing · Slow-cycle fatigue testing · High temperature testing to 2500°F · ASTM/ Boeing/ SACMA standard testing · Ability to design and fabricate non-standard test fixtures and perform non-standard tests