Sample records for national compact stellarator

  1. Gyrokinetic studies of the effect of {beta} on drift-wave stability in the National Compact Stellarator Experiment

    SciTech Connect (OSTI)

    Baumgaertel, J. A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); Hammett, G. W.; Mikkelsen, D. R. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Nunami, M. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Xanthopoulos, P. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstr. 1, 17491 Greifswald (Germany)

    2012-12-15T23:59:59.000Z

    The gyrokinetic turbulence code GS2 was used to investigate the effects of plasma {beta} on linear, collisionless ion temperature gradient (ITG) modes and trapped electron modes (TEM) in National Compact Stellarator Experiment (NCSX) geometry. Plasma {beta} affects stability in two ways: through the equilibrium and through magnetic fluctuations. The first was studied here by comparing ITG and TEM stability in two NCSX equilibria of differing {beta} values, revealing that the high {beta} equilibrium was marginally more stable than the low {beta} equilibrium in the adiabatic-electron ITG mode case. However, the high {beta} case had a lower kinetic-electron ITG mode critical gradient. Electrostatic and electromagnetic ITG and TEM mode growth rate dependencies on temperature gradient and density gradient were qualitatively similar. The second {beta} effect is demonstrated via electromagnetic ITG growth rates' dependency on GS2's {beta} input parameter. A linear benchmark with gyrokinetic codes GENE and GKV-X is also presented.

  2. Exploration of Compact Stellarators as Power Plants

    E-Print Network [OSTI]

    California at San Diego, University of

    Exploration of Compact Stellarators as Power Plants: Initial Results from ARIES-CS Study Farrokh, see: http://aries.ucsd.edu/ #12;Exploration and Optimization of Compact Stellarators as Power Plants in the context of power plant studies, e.g., particle loss Divertor (location, particle and energy distribution

  3. THE ARIES-CS COMPACT STELLARATOR FUSION POWER PLANT

    E-Print Network [OSTI]

    Raffray, A. René

    THE ARIES-CS COMPACT STELLARATOR FUSION POWER PLANT F. NAJMABADI* and A. R. RAFFRAY Center stellarator power plants, ARIES-CS, has been conducted to explore attrac- tive compact stellarator by earlier stellarator power plant studies had led to cost projections much higher than those of the advanced

  4. Exploratory Divertor Heat Load Studies for Compact Stellarator Reactors

    E-Print Network [OSTI]

    Raffray, A. René

    of the divertor system is described in Sec. III, together with the plate heat load profile, and the conditions is power reaching the plate, AD is the total plate area, Wpk is the design peak heat load limitExploratory Divertor Heat Load Studies for Compact Stellarator Reactors T.K. Maua , H. Mc

  5. The compactness of presupernova stellar cores

    SciTech Connect (OSTI)

    Sukhbold, Tuguldur; Woosley, S. E., E-mail: sukhbold@ucolick.org [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

    2014-03-01T23:59:59.000Z

    The success or failure of the neutrino-transport mechanism for producing a supernova in an evolved massive star is known to be sensitive not only to the mass of the iron core that collapses, but also to the density gradient in the silicon and oxygen shells surrounding that core. Here we study the systematics of a presupernova core's 'compactness' as a function of the mass of the star and the physics used in its calculation. Fine-meshed surveys of presupernova evolution are calculated for stars from 15 to 65 M {sub ?}. The metallicity and the efficiency of semiconvection and overshoot mixing are both varied and bare carbon-oxygen cores are explored as well as full hydrogenic stars. Two different codes, KEPLER and MESA, are used for the study. A complex interplay of carbon and oxygen burning, especially in shells, can cause rapid variations in the compactness for stars of very nearly the same mass. On larger scales, the distribution of compactness with main sequence mass is found to be robustly non-monotonic, implying islands of 'explodabilty,' particularly around 8-20 M {sub ?} and 25-30 M {sub ?}. The carbon-oxygen (CO) core mass of a presupernova star is a better, (though still ambiguous) discriminant of its core structure than the main sequence mass.

  6. Fusion Engineering and Design 81 (2006) 26792693 Recent progress in the ARIES compact stellarator study

    E-Print Network [OSTI]

    Najmabadi, Farrokh

    2006-01-01T23:59:59.000Z

    of compact stellarator power plants, ARIES-CS, was initiated recently to explore attractive compact are similar in size to advanced tokamak power plants. © 2006 Elsevier B.V. All rights reserved. Keywords: Fusion power plant; Compact stellarator Corresponding author. Tel.: +1 858 534 7869; fax: +1 858 822

  7. The ARIES-CS A Compact Stellarator Power Plant F. Najmabadi

    E-Print Network [OSTI]

    Najmabadi, Farrokh

    1 FT/P5-26 The ARIES-CS ­ A Compact Stellarator Power Plant F. Najmabadi University of California features as fusion power plants. A detailed and integrated study of compact stellarator configurations as power plants, ARIES-CS, was initiated recently. Configurations with A 6 and excellent quasi

  8. Compact Stellarator Power Plants Prospects, Technical Issue, and R&D Directions

    E-Print Network [OSTI]

    Najmabadi, Farrokh

    1 FT/P3-13 Compact Stellarator Power Plants ­ Prospects, Technical Issue, and R&D Directions F plant, ARIES-CS, are reported in this paper. The first major goal of the ARIES-CS research was to investigate whether stellarator power plants can be made to be similar in size to advanced tokamak variants

  9. A compact flexible pellet injector for the TJ-II stellarator

    SciTech Connect (OSTI)

    McCarthy, K. J.; Carmona, J. M. [Laboratory Nacional de Fusion, CIEMAT, Av. Complutense 22, 28040 Madrid (Spain); Combs, S. K.; Baylor, L. R.; Caughman, J. B. O.; Fehling, D. T.; Foust, C. R.; McGill, J. M.; Rasmussen, D. A. [Oak Ridge National Laboratory, P.O. Box 2009, Oak Ridge, Tennessee 37831-8071 (United States)

    2008-10-15T23:59:59.000Z

    A compact pellet injector is being built for the TJ-II stellarator. It is an upgraded version of the 'pellet injector in a suitcase' developed at Oak Ridge National Laboratory and installed on the Madison Symmetric Torus where it continues to be used in many plasma experiments. The design aim is to provide maximum flexibility at minimal cost, while allowing for future upgrades. It is a four-barrel system equipped with a cryogenic refrigerator for in situ hydrogen pellet formation, a combined mechanical punch/propellant valve system, pellet diagnostics, and an injection line, destined for use as an active diagnostic and for fueling. In order to fulfill both objectives it will be sufficiently flexible to permit pellets, with diameters from 0.4 to 1 mm, to be fabricated and accelerated to velocities from 150 to {approx}1000 m s{sup -1}.

  10. A compact Flexible Pellet Injector for the TJ-II Stellarator

    SciTech Connect (OSTI)

    McCarthy, K. J. [Harvard-Smithsonian Center for Astrophysics; Combs, Stephen Kirk [ORNL; Baylor, Larry R [ORNL; Caughman, John B [ORNL; Fehling, Dan T [ORNL; Foust, Charles R [ORNL; McGill, James M [ORNL; Carmona, J. M. [Laboratory Nacional de Fusion, CIEMAT; Rasmussen, David A [ORNL

    2008-01-01T23:59:59.000Z

    A compact pellet injector is being built for the TJ-II stellarator. It is an upgraded version of the pellet injector in a suitcase developed at Oak Ridge National Laboratory and installed on the Madison Symmetric Torus where it continues to be used in many plasma experiments. The design aim is to provide maximum flexibility at minimal cost, while allowing for future upgrades. It is a four-barrel system equipped with a cryogenic refrigerator for in situ hydrogen pellet formation, a combined mechanical punch/propellant valve system, pellet diagnostics, and an injection line, destined for use as an active diagnostic and for fueling. In order to fulfill both objectives it will be sufficiently flexible to permit pellets, with diameters from 0.4 to 1 mm, to be fabricated and accelerated to velocities from 150 to 1000 m s 1.

  11. United Nations Global Compact The UN Global Compact is a strategic policy initiative for

    E-Print Network [OSTI]

    Chatziantoniou, Damianos

    United Nations Global Compact The UN Global Compact is a strategic policy initiative for businesses in the world. The Global Compact pursues two complementary objectives: 1. Mainstream the ten principles the Millennium Development Goals (MDGs). Participation in the Global Compact is open to degree-granting academic

  12. Experimental demonstration of a compact stellarator magnetic trap using four circular coils

    SciTech Connect (OSTI)

    Pedersen, T. Sunn; Kremer, J.P.; Lefrancois, R.G.; Marksteiner, Q.; Sarasola, X.; Ahmad, N. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States); University of California-Berkeley, Berkeley, California 94720 (United States)

    2006-01-15T23:59:59.000Z

    An experimental demonstration of a compact stellarator magnetic trap created from four circular coils is presented. The coil manufacturing and assembly tolerances were on the order of 0.5-1%, far less stringent than most other stellarators. The simplicity, loose mechanical tolerances, and low cost of the trap design makes it feasible for stellarators to be used for a variety of novel physics experiments, in addition to their present use for magnetic confinement fusion. The experiment, the Columbia Non-neutral Torus, has several other desirable features such as no significant internal island chains and the lowest aspect ratio, A{<=}1.9, of any stellarator built to date.

  13. SAFETY ASSESSMENT OF THE ARIES COMPACT STELLARATOR DESIGN

    E-Print Network [OSTI]

    California at San Diego, University of

    -CS by report- ing radiological inventories, decay heat, and radioactive waste management optionsARIES-CS and the facility can meet the no-evacuation requirement. KEYWORDS: ARIES-CS, safety assessment, stellarator Note In this paper we examine the safety and environmen- tal performance of ARIES-CS by reporting radiological

  14. Exploration of Compact Stellarators as Power Plants: Initial Results from ARIES-CS Study Farrokh Najmabadi and the ARIES Team

    E-Print Network [OSTI]

    California at San Diego, University of

    Exploration of Compact Stellarators as Power Plants: Initial Results from ARIES-CS Study Farrokh study of compact stellarators as power plants, ARIES-CS, was initiated recently to advance our. It appears that devices with an overall size similar to those envisioned for tokamak power plants

  15. Modular Dual Coolant Pb-17Li Blanket Design For ARIES-CS Compact Stellarator Power Plant

    E-Print Network [OSTI]

    Raffray, A. René

    of the study. The preferred blanket concept is a dual coolant blanket with a He- cooled ferritic steel firstModular Dual Coolant Pb-17Li Blanket Design For ARIES-CS Compact Stellarator Power Plant X.R. Wanga from the engineering effort during the second phase of ARIES-CS study on the conceptual design

  16. The mass spectrum of compact remnants from the PARSEC stellar evolution tracks

    E-Print Network [OSTI]

    Spera, Mario; Bressan, Alessandro

    2015-01-01T23:59:59.000Z

    The mass spectrum of stellar-mass black holes (BHs) is highly uncertain. Dynamical mass measurements are available only for few ($\\sim{}10$) BHs in X-ray binaries, while theoretical models strongly depend on the hydrodynamics of supernova (SN) explosions and on the evolution of massive stars. In this paper, we present and discuss the mass spectrum of compact remnants that we obtained with SEVN, a new public population-synthesis code, which couples the PARSEC stellar evolution tracks with up-to-date recipes for SN explosion (depending on the Carbon-Oxygen mass of the progenitor, on the compactness of the stellar core at pre-SN stage, and on a recent two-parameter criterion based on the dimensionless entropy per nucleon at pre-SN stage). SEVN can be used both as a stand-alone code and in combination with direct-summation N-body codes (Starlab, HiGPUs). The PARSEC stellar evolution tracks currently implemented in SEVN predict significantly larger values of the Carbon-Oxygen core mass with respect to previous mod...

  17. The National Compact Stellarator Experiment at the Princeton...

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

    fissionable uranium used in present-day nuclear reactors, and the limitations of solar, hydro and wind alternatives. Based on the analyses in the EA, the DOE has determined that...

  18. 5/28/08 6:03 PMPrinceton University -PPPL to phase out compact stellarator experiment, upgrade spherical torus program Page 1 of 2http://www.princeton.edu/main/news/archive/S21/15/04A97/index.xml?section=topstories

    E-Print Network [OSTI]

    in an underestimation of its cost and a more prolonged construction process. An 18-month series of project reviews spherical torus program Page 1 of 2http://www.princeton.edu/main/news/archive/S21/15/04A97/index://www.pppl.gov/> (PPPL) will phase out construction of the National Compact Stellarator Experiment (NCSX) and instead

  19. Formation of Compact Stellar Clusters by High-Redshift Galaxy Outflows I: Nonequillibrium Coolant Formation

    E-Print Network [OSTI]

    Gray, William J

    2010-01-01T23:59:59.000Z

    We use high-resolution three-dimensional adaptive mesh refinement simulations to investigate the interaction of high-redshift galaxy outflows with low-mass virialized clouds of primordial composition. While atomic cooling allows star formation in objects with virial temperatures above $10^4$ K, "minihaloes" below this threshold are generally unable to form stars by themselves. However, these objects are highly susceptible to triggered star formation, induced by outflows from neighboring high-redshift starburst galaxies. Here we conduct a study of these interactions, focusing on cooling through non-equilibrium molecular hydrogen (H$_2$) and hydrogen deuteride (HD) formation. Tracking the non-equilibrium chemistry and cooling of 14 species and including the presence of a dissociating background, we show that shock interactions can transform minihaloes into extremely compact clusters of coeval stars. Furthermore, these clusters are all less than $\\approx 10^6 M_\\odot,$ and they are ejected from their parent dark...

  20. PDC (polycrystalline diamond compact) bit research at Sandia National Laboratories

    SciTech Connect (OSTI)

    Finger, J.T.; Glowka, D.A.

    1989-06-01T23:59:59.000Z

    From the beginning of the geothermal development program, Sandia has performed and supported research into polycrystalline diamond compact (PDC) bits. These bits are attractive because they are intrinsically efficient in their cutting action (shearing, rather than crushing) and they have no moving parts (eliminating the problems of high-temperature lubricants, bearings, and seals.) This report is a summary description of the analytical and experimental work done by Sandia and our contractors. It describes analysis and laboratory tests of individual cutters and complete bits, as well as full-scale field tests of prototype and commercial bits. The report includes a bibliography of documents giving more detailed information on these topics. 26 refs.

  1. Compact

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville Power Administration would like submit the followingth Lomonosov1 COMMUNITY

  2. Global Compact for Higher Education Institutions

    E-Print Network [OSTI]

    Global Compact for Higher Education Institutions Communicating on Progress for Université Laval Guide to the United Nations Global Compact for Higher Education Institutions: Implementing the Global to the United Nations Global Compact for Higher Education Institutions: Implementing the Global Compact

  3. Development of a compact in situ polarized {sup 3}He neutron spin filter at Oak Ridge National Laboratory

    SciTech Connect (OSTI)

    Jiang, C. Y.; Tong, X., E-mail: tongx@ornl.gov; Brown, D. R.; Kadron, B. J.; Robertson, J. L. [Instrument and Source Design Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Chi, S.; Christianson, A. D.; Winn, B. L. [Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2014-07-15T23:59:59.000Z

    We constructed a compact in situ polarized {sup 3}He neutron spin filter based on spin-exchange optical pumping which is capable of continuous pumping of the {sup 3}He gas while the system is in place in the neutron beam on an instrument. The compact size and light weight of the system simplifies its utilization on various neutron instruments. The system has been successfully tested as a neutron polarizer on the triple-axis spectrometer (HB3) and the hybrid spectrometer (HYSPEC) at Oak Ridge National Laboratory. Over 70% {sup 3}He polarization was achieved and maintained during the test experiments. Over 90% neutron polarization and an average of 25% transmission for neutrons of 14.7 meV and 15 meV was also obtained.

  4. Comparing linear ion-temperature-gradient-driven mode stability of the National Compact Stellarator Experiment and a shaped tokamak

    E-Print Network [OSTI]

    Hammett, Greg

    Experiment and a shaped tokamak J. A. Baumgaertel, G. W. Hammett, and D. R. Mikkelsen Citation: Phys. Plasmas superconducting tokamak Phys. Plasmas 20, 022311 (2013) Identification and control of plasma vertical position using neural network in Damavand tokamak Rev. Sci. Instrum. 84, 023504 (2013) On the toroidal plasma

  5. Collisionless microinstabilities in stellarators. II. Numerical simulations

    SciTech Connect (OSTI)

    Proll, J. H. E.; Xanthopoulos, P.; Helander, P. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstraße 1, 17491 Greifswald, Germany and Max-Planck/Princeton Research Center for Plasma Physics, 17491 Greifswald (Germany)] [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstraße 1, 17491 Greifswald, Germany and Max-Planck/Princeton Research Center for Plasma Physics, 17491 Greifswald (Germany)

    2013-12-15T23:59:59.000Z

    Microinstabilities exhibit a rich variety of behavior in stellarators due to the many degrees of freedom in the magnetic geometry. It has recently been found that certain stellarators (quasi-isodynamic ones with maximum-J geometry) are partly resilient to trapped-particle instabilities, because fast-bouncing particles tend to extract energy from these modes near marginal stability. In reality, stellarators are never perfectly quasi-isodynamic, and the question thus arises whether they still benefit from enhanced stability. Here, the stability properties of Wendelstein 7-X and a more quasi-isodynamic configuration, QIPC, are investigated numerically and compared with the National Compact Stellarator Experiment and the DIII-D tokamak. In gyrokinetic simulations, performed with the gyrokinetic code GENE in the electrostatic and collisionless approximation, ion-temperature-gradient modes, trapped-electron modes, and mixed-type instabilities are studied. Wendelstein 7-X and QIPC exhibit significantly reduced growth rates for all simulations that include kinetic electrons, and the latter are indeed found to be stabilizing in the energy budget. These results suggest that imperfectly optimized stellarators can retain most of the stabilizing properties predicted for perfect maximum-J configurations.

  6. advanced stellar compass: Topics by E-print Network

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

    the structure and evolution of single and multiple stars, compact objects, SNe, gamma-ray bursts, solar neutrinos, and extreme physics on stellar scales. Central to the progress...

  7. Progress Toward Attractive Stellarators

    SciTech Connect (OSTI)

    Neilson, G H; Brown, T G; Gates, D A; Lu, K P; Zarnstorff, M C; Boozer, A H; Harris, J H; Meneghini, O; Mynick, H E; Pomphrey, N; Reiman, A H

    2011-01-05T23:59:59.000Z

    The quasi-axisymmetric stellarator (QAS) concept offers a promising path to a more compact stellarator reactor, closer in linear dimensions to tokamak reactors than previous stellarator designs. Concept improvements are needed, however, to make it more maintainable and more compatible with high plant availability. Using the ARIES-CS design as a starting point, compact stellarator designs with improved maintenance characteristics have been developed. While the ARIES-CS features a through-the-port maintenance scheme, we have investigated configuration changes to enable a sector-maintenance approach, as envisioned for example in ARIES AT. Three approaches are reported. The first is to make tradeoffs within the QAS design space, giving greater emphasis to maintainability criteria. The second approach is to improve the optimization tools to more accurately and efficiently target the physics properties of importance. The third is to employ a hybrid coil topology, so that the plasma shaping functions of the main coils are shared more optimally, either with passive conductors made of high-temperature superconductor or with local compensation coils, allowing the main coils to become simpler. Optimization tools are being improved to test these approaches.

  8. MCZ 050411 1 Stellarator Reactors

    E-Print Network [OSTI]

    designs => Motivated development of more compact designs · SPPS projected cost of electricity similar Average Major Radius (m) ASRA-6C 20 m HSR-G 18 m SPPS 14 m FFHR-J 10 m ARIES-ST Spherical Torus 3.2 m to tokamaks, but higher initial capital cost · Stellarator reactors expected to operate in true ignition

  9. Stellar jets

    E-Print Network [OSTI]

    Thomas J. Maccarone

    2008-05-23T23:59:59.000Z

    With a goal of understanding the conditions under which jets might be produced in novae and related objects, I consider the conditions under which jets are produced from other classes of accreting compact objects. I give an overview of accretion disk spectral states, including a discussion of in which states these jets are seen. I highlight the differences between neutron stars and black holes, which may help give us insights about when and how the presence of a solid surface may help or inhibit jet production.

  10. Internship Description Title: Stellar Solutions Engineering Internship

    E-Print Network [OSTI]

    Virginia Tech

    Internship Description Title: Stellar Solutions ­ Engineering Internship Job Description: The internship will be held at the Stellar National Reconnaissance Office in Washington, DC. Tasks will require a background in intelligence, and familiar with all-source analysis. This internship is flexible throughout

  11. The Cooling of Compact Stars

    E-Print Network [OSTI]

    Dany Page; Ulrich Geppert; Fridolin Weber

    2005-08-01T23:59:59.000Z

    The cooling of a compact star depends very sensitively on the state of dense matter at supranuclear densities, which essentially controls the neutrino emission, as well as on the structure of the stellar outer layers which control the photon emission. Open issues concern the hyperon population, the presence of meson condensates, superfluidity and superconductivity, and the transition of confined hadronic matter to quark matter. This paper describes these issues and presents cooling calculations based on a broad collection of equations of state for neutron star matter and strange matter. These results are tested against the body of observed cooling data.

  12. STELLAR ENCOUNTER RATE IN GALACTIC GLOBULAR CLUSTERS

    SciTech Connect (OSTI)

    Bahramian, Arash; Heinke, Craig O.; Sivakoff, Gregory R.; Gladstone, Jeanette C., E-mail: bahramia@ualberta.ca [Department of Physics, University of Alberta, CCIS 4-183, Edmonton, AB, T5K 1V4 (Canada)

    2013-04-01T23:59:59.000Z

    The high stellar densities in the cores of globular clusters cause significant stellar interactions. These stellar interactions can produce close binary mass-transferring systems involving compact objects and their progeny, such as X-ray binaries and radio millisecond pulsars. Comparing the numbers of these systems and interaction rates in different clusters drives our understanding of how cluster parameters affect the production of close binaries. In this paper we estimate stellar encounter rates ({Gamma}) for 124 Galactic globular clusters based on observational data as opposed to the methods previously employed, which assumed 'King-model' profiles for all clusters. By deprojecting cluster surface brightness profiles to estimate luminosity density profiles, we treat 'King-model' and 'core-collapsed' clusters in the same way. In addition, we use Monte Carlo simulations to investigate the effects of uncertainties in various observational parameters (distance, reddening, surface brightness) on {Gamma}, producing the first catalog of globular cluster stellar encounter rates with estimated errors. Comparing our results with published observations of likely products of stellar interactions (numbers of X-ray binaries, numbers of radio millisecond pulsars, and {gamma}-ray luminosity) we find both clear correlations and some differences with published results.

  13. Pecos River Compact (Texas)

    Broader source: Energy.gov [DOE]

    This legislation authorizes the state's entrance into the Pecos River Compact, a joint agreement between the states of New Mexico and Texas. The compact is administered by the Pecos River Compact...

  14. Interstate Oil and Gas Conservation Compact (Multiple States)

    Broader source: Energy.gov [DOE]

    The Interstate Oil and Gas Compact Commission assists member states efficiently maximize oil and natural gas resources through sound regulatory practices while protecting the nation's health,...

  15. STELLAR STRUCTURE AND EVOLUTION

    E-Print Network [OSTI]

    Mojzsis, Stephen J.

    STELLAR STRUCTURE AND EVOLUTION O.R. Pols September 2009 #12;#12;Preface These lecture notes application to the theory of stellar structure and evolution, at a level appro- priate for a third and Evolution, 1990, Springer-Verlag, ISBN 3-540-50211-4 (KIPPENHAHN; K&W) Some sections of this book are still

  16. NSTX LTXPEGASUS Compact CTF

    E-Print Network [OSTI]

    Princeton Plasma Physics Laboratory

    isotope retention. ST-CTF Compact ST-CTF at ~ 10 MA range provide a compact nuclear component test to NSTX. Large vacuum vessel, no stabilizing plates, excellent set of profile and boundary diagnostics

  17. Red River Compact (Texas)

    Broader source: Energy.gov [DOE]

    The Red River Compact Commission administers the Red River Compact to ensure that Texas receives its equitable share of quality water from the Red River and its tributaries as apportioned by the...

  18. Rio Grande Compact (Texas)

    Broader source: Energy.gov [DOE]

    This legislation authorizes the state's entrance into the Rio Grande Compact, a joint agreement between the states of Colorado, New Mexico, and Texas. The compact is administered by the Rio Grande...

  19. Canadian River Compact (Texas)

    Broader source: Energy.gov [DOE]

    The Canadian River Commission administers the Canadian River Compact which includes the states of New Mexico, Oklahoma, and Texas. Signed in 1950 by the member states, the Compact was subsequently...

  20. Stellar Evolution A Statistical Model

    E-Print Network [OSTI]

    van Dyk, David

    Stellar Evolution A Statistical Model Statistical Computation Analysis of the Hyades Cluster Statistical Analysis of Stellar Evolution David A. van Dyk1 Steven DeGennaro2 Nathan Stein2 William H Statistical Analysis of Stellar Evolution #12;Stellar Evolution A Statistical Model Statistical Computation

  1. Stellar Evolution A Statistical Model

    E-Print Network [OSTI]

    van Dyk, David

    Stellar Evolution A Statistical Model Statistical Computation Analysis of the Hyades Cluster Embedding Computer Models for Stellar Evolution into a Coherent Statistical Analysis David A. van Dyk1 Analysis of Stellar Evolution #12;Stellar Evolution A Statistical Model Statistical Computation Analysis

  2. A technique for extending by ?10{sup 3} the dynamic range of compact proton spectrometers for diagnosing ICF implosions on the National Ignition Facility and OMEGA

    SciTech Connect (OSTI)

    Sio, H., E-mail: hsio@mit.edu; Séguin, F. H.; Frenje, J. A.; Gatu Johnson, M.; Zylstra, A. B.; Rinderknecht, H. G.; Rosenberg, M. J.; Li, C. K.; Petrasso, R. D. [Massachusetts Institute of Technology Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States)

    2014-11-15T23:59:59.000Z

    Wedge Range Filter (WRF) proton spectrometers are routinely used on OMEGA and the NIF for diagnosing ?R and ?R asymmetries in direct- and indirect-drive implosions of D{sup 3}He-, D{sub 2}-, and DT-gas-filled capsules. By measuring the optical opacity distribution in CR-39 due to proton tracks in high-yield applications, as opposed to counting individual tracks, WRF dynamic range can be extended by 10{sup 2} for obtaining the spectral shape, and by 10{sup 3} for mean energy (?R) measurement, corresponding to proton fluences of 10{sup 8} and 10{sup 9} cm{sup ?2}, respectively. Using this new technique, ?R asymmetries can be measured during both shock and compression burn (proton yield ?10{sup 8} and ?10{sup 12}, respectively) in 2-shock National Ignition Facility implosions with the standard WRF accuracy of ±?10 mg/cm{sup 2}.

  3. Progress in the Engineering Design of the National Compact Stellarator Experiment W.T. Reiersen 1 , A. Brooks 1 , T. Brown 1 , M. Cole 2 , HM. Fan 1 , P. Goranson, P. Heitzenroeder 1 , B. Nelson 2 ,

    E-Print Network [OSTI]

    transform remains monotonic with adequate reverse shear. NCSX plasma configurations are optimized (NCSX) is a proof­of­principle experiment whose objective is to demonstrate high beta operation. Many of the existing site assets including the test cell, TF and PF coils, power supplies, neutral beam

  4. MODEST-1: Integrating Stellar Evolution and Stellar Dynamics

    E-Print Network [OSTI]

    Piet Hut; Michael M. Shara; Sverre J. Aarseth; Ralf S. Klessen; James C. Lombardi Jr.; Junichiro Makino; Steve McMillan; Onno R. Pols; Peter J. Teuben; Ronald F. Webbink

    2002-11-01T23:59:59.000Z

    We summarize the main results from MODEST-1, the first workshop on MOdeling DEnse STellar systems. Our goal is to go beyond traditional population synthesis models, by introducing dynamical interactions between single stars, binaries, and multiple systems. The challenge is to define and develop a software framework to enable us to combine in one simulation existing computer codes in stellar evolution, stellar dynamics, and stellar hydrodynamics. With this objective, the workshop brought together experts in these three fields, as well as other interested astrophysicists and computer scientists. We report here our main conclusions, questions and suggestions for further steps toward integrating stellar evolution and stellar (hydro)dynamics.

  5. Interstate Mining Compact (Maryland)

    Broader source: Energy.gov [DOE]

    This legislation authorizes the state's entrance into the Interstate Mining Compact, a multi-state governmental agency / organization that represents the natural resource and related environmental...

  6. Opacity of stellar matter

    SciTech Connect (OSTI)

    Rogers, F J

    1998-09-17T23:59:59.000Z

    New efforts to calculate opacity have produced significant improvements in the quality of stellar models. The most dramatic effect has been large opacity enhancements for stars subject to large amplitude pulsations. Significant improvement in helioseismic modeling has also been obtained. A description and comparisons of the new opacity efforts are give

  7. Laboratory compaction of cohesionless sands

    E-Print Network [OSTI]

    Delphia, John Girard

    1998-01-01T23:59:59.000Z

    on the maximum dry unit weight during compaction. Three different laboratory compaction methods were used: 1) Standard Proctor', 2) Modified Proctor; and 3) Vibrating hammer. The effects of the grain size distribution, particle shape and laboratory compaction...

  8. Sandia National Laboratories: compact toroid formation

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

    Analysis, Systems Engineering Sandian Dean Buchenauer (in Sandia's Hydrogen and Metallurgy Science Dept.) and Professor David Q. Hwang (UC Davis, School of Engineering) will...

  9. Compact Remnant Mass Function: Dependence on the Explosion Mechanism and Metallicity

    E-Print Network [OSTI]

    Fryer, C L; Wiktorowicz, G; Dominik, M; Kalogera, V; Holz, D

    2011-01-01T23:59:59.000Z

    The mass distribution of neutron stars and stellar-mass black holes provides vital clues into the nature of stellar core collapse and the physical engine responsible for supernova explosions. Using recent advances in our understanding of supernova engines, we derive mass distributions of stellar compact remnants. We provide analytical prescriptions for compact object masses for major population synthesis codes. In an accompanying paper, Belczynski et al., we demonstrate that these qualitatively new results for compact objects can explain the observed gap in the remnant mass distribution between ~2-5 solar masses and that they place strong constraints on the nature of the supernova engine. Here, we show that advanced gravitational radiation detectors (like LIGO/VIRGO or the Einstein Telescope) will be able to further test the supernova explosion engine models once double black hole inspirals are detected.

  10. Compact microchannel system

    DOE Patents [OSTI]

    Griffiths, Stewart

    2003-09-30T23:59:59.000Z

    The present invention provides compact geometries for the layout of microchannel columns through the use of turns and straight channel segments. These compact geometries permit the use of long separation or reaction columns on a small microchannel substrate or, equivalently, permit columns of a fixed length to occupy a smaller substrate area. The new geometries are based in part on mathematical analyses that provide the minimum turn radius for which column performance in not degraded. In particular, we find that straight channel segments of sufficient length reduce the required minimum turn radius, enabling compact channel layout when turns and straight segments are combined. The compact geometries are obtained by using turns and straight segments in overlapped or nested arrangements to form pleated or coiled columns.

  11. COMPACT ACCELERATOR CONCEPT FOR PROTON THERAPY

    SciTech Connect (OSTI)

    Caporaso, G; Sampayan, S; Chen, Y; Harris, J; Hawkins, S; Holmes, C; Krogh, M; Nelson, S; Nunnally, W; Paul, A; Poole, B; Rhodes, M; Sanders, D; Selenes, K; Sullivan, J; Wang, L; Watson, J

    2006-08-18T23:59:59.000Z

    A new type of compact induction accelerator is under development at the Lawrence Livermore National Laboratory that promises to increase the average accelerating gradient by at least an order of magnitude over that of existing induction machines. The machine is based on the use of high gradient vacuum insulators, advanced dielectric materials and switches and is being developed as a compact flash x-ray radiography source. Research describing an extreme variant of this technology aimed at proton therapy for cancer will be presented.

  12. UNIFYING THE ZOO OF JET-DRIVEN STELLAR EXPLOSIONS

    SciTech Connect (OSTI)

    Lazzati, Davide; Blackwell, Christopher H. [Department of Physics, NC State University, 2401 Stinson Drive, Raleigh, NC 27695-8202 (United States); Morsony, Brian J. [Department of Astronomy, University of Wisconsin-Madison, 2535 Sterling Hall, 475 N. Charter Street, Madison WI 53706-1582 (United States); Begelman, Mitchell C. [JILA, University of Colorado, 440 UCB, Boulder, CO 80309-0440 (United States)

    2012-05-01T23:59:59.000Z

    We present a set of numerical simulations of stellar explosions induced by relativistic jets emanating from a central engine sitting at the center of compact, dying stars. We explore a wide range of durations of the central engine activity, two candidate stellar progenitors, and two possible values of the total energy release. We find that even if the jets are narrowly collimated, their interaction with the star unbinds the stellar material, producing a stellar explosion. We also find that the outcome of the explosion can be very different depending on the duration of the engine activity. Only the longest-lasting engines result in successful gamma-ray bursts. Engines that power jets only for a short time result in relativistic supernova (SN) explosions, akin to observed engine-driven SNe such as SN2009bb. Engines with intermediate durations produce weak gamma-ray bursts, with properties similar to nearby bursts such as GRB 980425. Finally, we find that the engines with the shortest durations, if they exist in nature, produce stellar explosions that lack sizable amounts of relativistic ejecta and are therefore dynamically indistinguishable from ordinary core-collapse SNe.

  13. Industrial Optimization Compact Course

    E-Print Network [OSTI]

    Kirches, Christian

    Industrial Optimization Compact Course and Challenge Workshop Optimization plays a crucial role of the processes are typically nonlinear and dyna- mic. Thus, complex dynamic optimization or optimal control in industrial optimization. February 17­20, 2014 ·9.00­17.00 IWR ·Im Neuenheimer Feld 368 ·69120 Heidelberg www

  14. COSMOLOGICAL SIMULATIONS OF MASSIVE COMPACT HIGH-z GALAXIES

    SciTech Connect (OSTI)

    Sommer-Larsen, J.; Toft, S., E-mail: jslarsen@astro.ku.d, E-mail: sune@dark-cosmology.d [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Mariesvej 30, DK-2100 Copenhagen (Denmark)

    2010-10-01T23:59:59.000Z

    In order to investigate the structure and dynamics of the recently discovered massive (M{sub *} {approx}> 10{sup 11} M{sub sun}) compact z {approx} 2 galaxies, cosmological hydrodynamical/N-body simulations of a {approx}50,000 Mpc{sup 3} comoving (Lagrangian), proto-cluster region have been undertaken. At z = 2, the highest resolution simulation contains {approx}5800 resolved galaxies, of which 509, 27, and 5 have M{sub *}>10{sup 10} M{sub sun}, M{sub *}>10{sup 11} M{sub sun}, and M{sub *}>4 x 10{sup 11} M{sub sun}, respectively. Total stellar masses, effective radii, and characteristic stellar densities have been determined for all galaxies. At z = 2, for the definitely well-resolved mass range of M{sub *} {approx}> 10{sup 11} M{sub sun}, we fit the relation R{sub eff} = R{sub eff,12} M {sup 1/3}{sub *,12} to the data, where M{sub *,12} is the total stellar mass in units of 10{sup 12} M{sub sun}. This yields R{sub eff,12} = (1.20 {+-} 0.04) kpc, in line with observational findings for compact z {approx} 2 galaxies, though somewhat more compact than the observed average. The only line-of-sight velocity dispersion measured for a z {approx} 2 compact galaxy is very large, {sigma}{sub *,p} = 510{sup +165}{sub -95} km s{sup -1}. This value can be matched at about the 1{sigma} level, although a somewhat larger mass than the estimated M{sub *} {approx_equal} 2 x 10{sup 11} M{sub sun} is indicated. For the above mass range, the galaxies have an average axial ratio (b/a) = 0.64 {+-} 0.02 with a dispersion of 0.1, and an average rotation to one-dimensional velocity-dispersion ratio (v/{sigma}) = 0.46 {+-} 0.06 with a dispersion of 0.3, and a maximum value of v/{sigma} {approx_equal} 1.1. Both rotation and velocity anisotropy contribute significantly in flattening the compact galaxies. Some of the observed compact galaxies appear flatter than any of the simulated galaxies. Finally, it is found that the massive compact galaxies are strongly baryon dominated in their inner parts, with typical dark matter mass fractions of order only 20% inside of r = 2 R{sub eff}.

  15. The Dartmouth Stellar Evolution Database

    E-Print Network [OSTI]

    Aaron Dotter; Brian Chaboyer; Darko Jevremovic; Veselin Kostov; E. Baron; J. W. Ferguson

    2008-04-28T23:59:59.000Z

    The ever-expanding depth and quality of photometric and spectroscopic observations of stellar populations increase the need for theoretical models in regions of age-composition parameter space that are largely unexplored at present. Stellar evolution models that employ the most advanced physics and cover a wide range of compositions are needed to extract the most information from current observations of both resolved and unresolved stellar populations. The Dartmouth Stellar Evolution Database is a collection of stellar evolution tracks and isochrones that spans a range of [Fe/H] from -2.5 to +0.5, [alpha/Fe] from -0.2 to +0.8 (for [Fe/H] 0), and initial He mass fractions from Y=0.245 to 0.40. Stellar evolution tracks were computed for masses between 0.1 and 4 Msun, allowing isochrones to be generated for ages as young as 250 Myr. For the range in masses where the core He flash occurs, separate He-burning tracks were computed starting from the zero age horizontal branch. The tracks and isochrones have been transformed to the observational plane in a variety of photometric systems including standard UBV(RI)c, Stromgren uvby, SDSS ugriz, 2MASS JHKs, and HST ACS-WFC and WFPC2. The Dartmouth Stellar Evolution Database is accessible through a website at http://stellar.dartmouth.edu/~models/ where all tracks, isochrones, and additional files can be downloaded.

  16. Stellar science unveiled at space conference

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del Sol HomeFacebookScholarshipSpiraling LaserAppropriations ScientificStefanStellar

  17. Progress in Compact Toroid Experiments

    SciTech Connect (OSTI)

    Dolan, Thomas James

    2002-09-01T23:59:59.000Z

    The term "compact toroids" as used here means spherical tokamaks, spheromaks, and field reversed configurations, but not reversed field pinches. There are about 17 compact toroid experiments under construction or operating, with approximate parameters listed in Table 1.

  18. Sabine River Compact (Multiple States)

    Broader source: Energy.gov [DOE]

    The Sabine River Compact Commission administers the Sabine River Compact to ensure that Texas receives its equitable share of quality water from the Sabine River and its tributaries as apportioned...

  19. Strange Quark Matter and Compact Stars

    E-Print Network [OSTI]

    Fridolin Weber

    2004-09-27T23:59:59.000Z

    Astrophysicists distinguish between three different types of compact stars. These are white dwarfs, neutron stars, and black holes. The former contain matter in one of the densest forms found in the Universe which, together with the unprecedented progress in observational astronomy, make such stars superb astrophysical laboratories for a broad range of most striking physical phenomena. These range from nuclear processes on the stellar surface to processes in electron degenerate matter at subnuclear densities to boson condensates and the existence of new states of baryonic matter--like color superconducting quark matter--at supernuclear densities. More than that, according to the strange matter hypothesis strange quark matter could be more stable than nuclear matter, in which case neutron stars should be largely composed of pure quark matter possibly enveloped in thin nuclear crusts. Another remarkable implication of the hypothesis is the possible existence of a new class of white dwarfs. This article aims at giving an overview of all these striking physical possibilities, with an emphasis on the astrophysical phenomenology of strange quark matter. Possible observational signatures associated with the theoretically proposed states of matter inside compact stars are discussed as well. They will provide most valuable information about the phase diagram of superdense nuclear matter at high baryon number density but low temperature, which is not accessible to relativistic heavy ion collision experiments.

  20. Compact Spreader Schemes

    SciTech Connect (OSTI)

    Placidi, M.; Jung, J. -Y.; Ratti, A.; Sun, C.

    2014-07-25T23:59:59.000Z

    This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibility when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.

  1. EXPLORING THE INTERSTELLAR MEDIA OF OPTICALLY COMPACT DWARF GALAXIES

    SciTech Connect (OSTI)

    Most, Hans P.; Cannon, John M.; Engstrom, Eric; Fliss, Palmer [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); Salzer, John J. [Department of Astronomy, Indiana University, 727 East Third Street, Bloomington, IN 47405 (United States); Rosenberg, Jessica L., E-mail: hmost@macalester.edu, E-mail: jcannon@macalester.edu, E-mail: slaz@astro.indiana.edu, E-mail: jrosenb4@gmu.edu [School of Physics, Astronomy, and Computational Science, George Mason University, Fairfax, VA 22030 (United States)

    2013-06-15T23:59:59.000Z

    We present new Very Large Array H I spectral line, archival Sloan Digital Sky Survey, and archival Spitzer Space Telescope imaging of eight star-forming blue compact dwarf galaxies that were selected to be optically compact (optical radii <1 kpc). These systems have faint blue absolute magnitudes (M{sub B} {approx}> -17), ongoing star formation (based on emission-line selection by the H{alpha} or [O III] lines), and are nearby (mean velocity = 3315 km s{sup -1} {approx_equal} 45 Mpc). One galaxy in the sample, ADBS 113845+2008, is found to have an H I halo that extends 58 r-band scale lengths from its stellar body. In contrast, the rest of the sample galaxies have H I radii to optical-scale-length ratios ranging from 9.3 to 26. The size of the H I disk in the 'giant disk' dwarf galaxy ADBS 113845+2008 appears to be unusual as compared with similarly compact stellar populations.

  2. Compact High Velocity Clouds

    E-Print Network [OSTI]

    Robert Braun

    2000-09-01T23:59:59.000Z

    We summarize the observed properties of the CHVC population, which provide strong evidence for source distances in the range 200-1000 kpc. At these distances, the population corresponds to strongly dark-matter dominated sub-dwarf galaxies still accreting onto the more massive Local Group systems. Recent searches for faint associated stellar populations have revealed red-giant candidates for which follow-up spectroscopy is scheduled. A sensitive HI survey for CHVC counterparts in the NGC 628 galaxy group has allowed tentative detection of 40 candidates, for which confirming observations have been approved. Many open issues should be resolved by observational programs within the coming years.

  3. Electron Screening Effect on Stellar Thermonuclear Fusion

    E-Print Network [OSTI]

    K. -h. Spatschek; M. Bonitz; T. Klinger; U. Ebert; C. Franck; A. V. Keudell; D. Naujoks; M. Dewitz; A. Y. Potekhin; G. Chabrier

    2012-01-01T23:59:59.000Z

    thermonuclear fusions and show that these scenarios do not apply to stellar conditions. c ? 2013 WILEY

  4. Accretion in Compact Binaries

    E-Print Network [OSTI]

    Andrew R. King

    2003-03-26T23:59:59.000Z

    Compact binaries have long been a paradigm for accretion theory. Much of our present view of how accretion occurs comes directly from the comparison of theory with observations of these sources. Since theory differs little for other objects such as active galaxies, increasing efforts have recently gone into searching for correspondences in observed behaviour. This chapter aims at giving a concise summary of the field, with particular emphasis on new developments since the previous edition of this book. These developments have been significant. Much of the earlier literature implicitly assumed that accreting binaries were fairly steady sources accreting most of the mass entering their vicinity, often with main-sequence companions, and radiating the resulting accretion luminosity in rough isotropy. We shall see that in reality these assumptions fail for the majority of systems. Most are transient; mass ejection in winds and jets is extremely common; a large (sometimes dominant) fraction of even short-period systems have evolved companions whose structure deviates significantly from the zero-age main sequence; and the radiation pattern of many objects is significantly anisotropic. It is now possible to give a complete characterization of the observed incidence of transient and persistent sources in terms of the disc instability model and formation constraints. X-ray populations in external galaxies, particularly the ultraluminous sources, are revealing important new insights into accretion processes and compact binary evolution.

  5. Susquehanna River Basin Compact (Maryland)

    Broader source: Energy.gov [DOE]

    This legislation enables the state's entrance into the Susquehanna River Basin Compact, which provides for the conservation, development, and administration of the water resources of the...

  6. Folded Compact Range Development and Coherent Change Detection Measurement Project

    SciTech Connect (OSTI)

    Sorensen, K.W.

    1995-03-01T23:59:59.000Z

    A novel, folded compact range configuration has been developed at the Sandia National Laboratories compact range antenna and radar cross section measurement facility, operated by the Radar/Antenna Department 2343, as a means of performing indoor, environmentally-controlled, far-field simulations of synthetic aperture radar (SAR) coherent change detection (CCD) measurements. This report describes the development of the folded compact range configuration, as well as the initial set of coherent change detection measurements made with the system. These measurements have been highly successful, and have demonstrated the viability of the folded compact range concept in simulating SAR CCD measurements. It is felt that follow-on measurements have the potential of contributing significantly to the body of knowledge available to the scientific community involved in CCD image generation and processing, and that this tool will be a significant aid in the research and development of change detection methodologies.

  7. Stellar and Intermediate-Mass Black Holes in the Milky Way and Nearby Galaxies

    SciTech Connect (OSTI)

    Irwin, Jimmy [Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487-0324 (United States)

    2010-08-09T23:59:59.000Z

    With the advent of high resolution X-ray telescopes, the ability to identify extragalactic black holes has greatly enhanced our understanding of massive compact objects, as we are no longer limited to the rather meager Milky Way black hole population. The greatly increased numbers have opened up opportunities to find new modes of compact object accretion and potentially long-sought evidence for intermediate-mass black holes. In this lecture series, the current state of knowledge of stellar- and intermediate-mass black holes is reviewed, particularly in regards to black hole populations in external galaxies.

  8. Compact acoustic refrigerator

    DOE Patents [OSTI]

    Bennett, G.A.

    1992-11-24T23:59:59.000Z

    A compact acoustic refrigeration system actively cools components, e.g., electrical circuits, in a borehole environment. An acoustic engine includes first thermodynamic elements for generating a standing acoustic wave in a selected medium. An acoustic refrigerator includes second thermodynamic elements located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements and a relatively hot temperature at a second end of the second thermodynamic elements. A resonator volume cooperates with the first and second thermodynamic elements to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements, first heat pipes transfer heat from the heat load to the second thermodynamic elements and second heat pipes transfer heat from first and second thermodynamic elements to the borehole environment. 18 figs.

  9. Compact acoustic refrigerator

    DOE Patents [OSTI]

    Bennett, Gloria A. (Los Alamos, NM)

    1992-01-01T23:59:59.000Z

    A compact acoustic refrigeration system actively cools components, e.g., electrical circuits (22), in a borehole environment. An acoustic engine (12, 14) includes first thermodynamic elements (12) for generating a standing acoustic wave in a selected medium. An acoustic refrigerator (16, 26, 28) includes second thermodynamic elements (16) located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements (16) and a relatively hot temperature at a second end of the second thermodynamic elements (16). A resonator volume (18) cooperates with the first and second thermodynamic elements (12, 16) to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements (12, 16), first heat pipes (24, 26) transfer heat from the heat load (22) to the second thermodynamic elements (16) and second heat pipes (28, 32) transfer heat from first and second thermodynamic elements (12, 16) to the borehole environment.

  10. Compact vacuum insulation embodiments

    DOE Patents [OSTI]

    Benson, D.K.; Potter, T.F.

    1992-04-28T23:59:59.000Z

    An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially point' or line' contacts with the metal wall sheets. In the case of monolithic spacers that form line' contacts, two such spacers with the line contacts running perpendicular to each other form effectively point' contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included. 26 figs.

  11. Compact vacuum insulation

    DOE Patents [OSTI]

    Benson, David K. (Golden, CO); Potter, Thomas F. (Denver, CO)

    1993-01-01T23:59:59.000Z

    An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially "point" or "line" contacts with the metal wall sheets. In the case of monolithic spacers that form "line" contacts, two such spacers with the line contacts running perpendicular to each other form effectively "point" contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.

  12. Compact vacuum insulation

    DOE Patents [OSTI]

    Benson, D.K.; Potter, T.F.

    1993-01-05T23:59:59.000Z

    An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially point'' or line'' contacts with the metal wall sheets. In the case of monolithic spacers that form line'' contacts, two such spacers with the line contacts running perpendicular to each other form effectively point'' contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.

  13. Compact vacuum insulation embodiments

    DOE Patents [OSTI]

    Benson, David K. (Golden, CO); Potter, Thomas F. (Denver, CO)

    1992-01-01T23:59:59.000Z

    An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially "point" or "line" contacts with the metal wall sheets. In the case of monolithic spacers that form "line" contacts, two such spacers with the line contacts running perpendicular to each other form effectively "point" contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.

  14. Compact stars with a quark core within the Nambu-Jona-Lasinio (NJL) model

    SciTech Connect (OSTI)

    Lenzi, C. H. [Departamento de Fisica, Instituto Tecnologico de Aeronautica, Campo Montenegro, Sao Jose dos Campos, SP, 12228-900 (Brazil); Centro de Fisica Computacional, Department of Physics, University of Coimbra, Rua Larga, Coimbra, P-3004-516 (Portugal); Schneider, A. S. [Department of Physics, Indiana University, Swain Hall West 117, 727 East Third Street Bloomington, Indiana 47405 (United States); Providencia, C. [Centro de Fisica Computacional, Department of Physics, University of Coimbra, Rua Larga, Coimbra, P-3004-516 (Portugal); Marinho, R. M. Jr. [Departamento de Fisica, Instituto Tecnologico de Aeronautica, Campo Montenegro, Sao Jose dos Campos, SP, 12228-900 (Brazil)

    2010-07-15T23:59:59.000Z

    An ultraviolet cutoff dependent on the chemical potential as proposed by Casalbuoni et al. is used in the SU(3) Nambu-Jona-Lasinio model. The model is applied to the description of stellar quark matter and compact stars. It is shown that with a new cutoff parametrization it is possible to obtain stable hybrid stars with a quark core. A larger cutoff at finite densities leads to a partial chiral symmetry restoration of quark s at lower densities. A direct consequence is the onset of the s quark in stellar matter at lower densities and a softening of the equation of state.

  15. Use of a BCD for compaction control

    E-Print Network [OSTI]

    Li, Yanfeng

    2005-11-01T23:59:59.000Z

    Compaction of soil is essential in the construction of highways, airports, buildings, and bridges. Typically compaction is controlled by measuring the dry density and the water content of the compacted soil and checking that target values have been...

  16. The stellar population of bulges

    E-Print Network [OSTI]

    P. Jablonka

    2007-01-07T23:59:59.000Z

    This review summarizes the properties of the stellar population in bulges as observed in nearby or distant spiral galaxies. It gives a particular emphasis to the comparison with elliptical galaxies, when possible. The criteria of sample selection and choices in data analysis are addressed when they may be involved in discrepant results reached by different studies.

  17. The Evolution of Stellar Populations

    E-Print Network [OSTI]

    Angeles Diaz; Eduardo Hardy

    2001-03-14T23:59:59.000Z

    We summarize the discussion section on ``Evolution of Stellar Populations'' we led on May 27, 2000 in Granada, Spain, as part of the Euroconference on The Evolution of Galaxies. I- Observational Clues. We also provide a partial comparison between the present knowledge of these topics and that which existed at the time of the Crete Conference of 1995.

  18. Stellar populations of bulges at low redshift

    E-Print Network [OSTI]

    Sanchez-Blazquez, Patricia

    2015-01-01T23:59:59.000Z

    This chapter summarizes our current understanding of the stellar population properties of bulges and outlines important future research directions.

  19. Compact vacuum insulation

    DOE Patents [OSTI]

    Benson, D.K.; Potter, T.F.

    1992-10-27T23:59:59.000Z

    Improved compact insulation panel is provided which is comprised of two adjacent metal sheets spaced close together with a plurality of spherical, or other discretely shaped, glass or ceramic beads optimally positioned between the sheets to provide support and maintain the spacing between the metal sheets when the gases there between are evacuated to form a vacuum. These spherical glass beads provide the maximum support while minimizing thermal conductance. In its preferred embodiment; these two metal sheets are textured with ribs or concave protrusions in conjunction with the glass beads to maximize the structural integrity of the panels while increasing the spacing between beads, thereby reducing the number of beads and the number of thermal conduction paths. Glass or porcelain-enameled liners in combination with the glass spacers and metal sidewalls effectively decrease thermal conductivity, and various laminates, including wood, porcelain-enameled metal, and others effectively increase the strength and insulation capabilities of the panels. Also, a metal web is provided to hold the spacers in place, and strategic grooves are shown to accommodate expansion and contraction or shaping of the panels. 35 figs.

  20. Compact vacuum insulation

    DOE Patents [OSTI]

    Benson, David K. (Golden, CO); Potter, Thomas F. (Denver, CO)

    1992-01-01T23:59:59.000Z

    Improved compact insulation panel is provided which is comprised of two adjacent metal sheets spaced close together with a plurality of spherical, or other discretely shaped, glass or ceramic beads optimally positioned between the sheets to provide support and maintain the spacing between the metal sheets when the gases therebetween are evacuated to form a vacuum. These spherical glass beads provide the maximum support while minimizing thermal conductance. In its preferred embodiment; these two metal sheets are textured with ribs or concave protrusions in conjunction with the glass beads to maximize the structural integrity of the panels while increasing the spacing between beads, thereby reducing the number of beads and the number of thermal conduction paths. Glass or porcelain-enameled liners in combination with the glass spacers and metal sidewalls effectively decrease thermal conductivity, and variious laminates, including wood, porcelain-enameled metal, and others effectively increase the strength and insulation capabilities of the panels. Also, a metal web is provided to hold the spacers in place, and strategic grooves are shown to accommodate expansion and contraction or shaping of the panels.

  1. Compact neutron generator

    DOE Patents [OSTI]

    Leung, Ka-Ngo; Lou, Tak Pui

    2005-03-22T23:59:59.000Z

    A compact neutron generator has at its outer circumference a toroidal shaped plasma chamber in which a tritium (or other) plasma is generated. A RF antenna is wrapped around the plasma chamber. A plurality of tritium ion beamlets are extracted through spaced extraction apertures of a plasma electrode on the inner surface of the toroidal plasma chamber and directed inwardly toward the center of neutron generator. The beamlets pass through spaced acceleration and focusing electrodes to a neutron generating target at the center of neutron generator. The target is typically made of titanium tubing. Water is flowed through the tubing for cooling. The beam can be pulsed rapidly to achieve ultrashort neutron bursts. The target may be moved rapidly up and down so that the average power deposited on the surface of the target may be kept at a reasonable level. The neutron generator can produce fast neutrons from a T-T reaction which can be used for luggage and cargo interrogation applications. A luggage or cargo inspection system has a pulsed T-T neutron generator or source at the center, surrounded by associated gamma detectors and other components for identifying explosives or other contraband.

  2. Compaction managed mirror bend achromat

    DOE Patents [OSTI]

    Douglas, David (Yorktown, VA)

    2005-10-18T23:59:59.000Z

    A method for controlling the momentum compaction in a beam of charged particles. The method includes a compaction-managed mirror bend achromat (CMMBA) that provides a beamline design that retains the large momentum acceptance of a conventional mirror bend achromat. The CMMBA also provides the ability to tailor the system momentum compaction spectrum as desired for specific applications. The CMMBA enables magnetostatic management of the longitudinal phase space in Energy Recovery Linacs (ERLs) thereby alleviating the need for harmonic linearization of the RF waveform.

  3. CAN STELLAR MIXING EXPLAIN THE LACK OF TYPE Ib SUPERNOVAE IN LONG-DURATION GAMMA-RAY BURSTS?

    SciTech Connect (OSTI)

    Frey, Lucille H. [HPC-3, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Fryer, Chris L. [CCS-2, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Young, Patrick A. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85276 (United States)

    2013-08-10T23:59:59.000Z

    The discovery of supernovae associated with long-duration gamma-ray burst observations is primary evidence that the progenitors of these outbursts are massive stars. One of the principle mysteries in understanding these progenitors has been the fact that all of these gamma-ray-burst-associated supernovae are Type Ic supernovae with no evidence of helium in the stellar atmosphere. Many studies have focused on whether or not this helium is simply hidden from spectral analyses. In this Letter, we show results from recent stellar models using new convection algorithms based on our current understanding of stellar mixing. We demonstrate that enhanced convection may lead to severe depletion of stellar helium layers, suggesting that the helium is not observed simply because it is not in the star. We also present light curves and spectra of these compact helium-depleted stars compared to models with more conventional helium layers.

  4. New considerations for compact cyclotrons

    E-Print Network [OSTI]

    Marshall, Eric S. (Eric Scott)

    2012-01-01T23:59:59.000Z

    A compact cyclotron built with superconducting magnets could be a transformative solution to many scientific problems facing the defense, medical, and energy industries today. This thesis discusses three potential applications ...

  5. MESOSCALE SIMULATIONS OF POWDER COMPACTION

    SciTech Connect (OSTI)

    Lomov, Ilya; Fujino, Don; Antoun, Tarabay; Liu, Benjamin [Lawrence Livermore National Laboratory, P. O. Box 808, Livermore CA 94551 (United States)

    2009-12-28T23:59:59.000Z

    Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.

  6. Yellowstone River Compact (North Dakota)

    Broader source: Energy.gov [DOE]

    The Yellowstone River Compact, agreed to by the States of Montana, North Dakota, and Wyoming, provides for an equitable division and apportionment of the waters of the Yellowstone River, as well as...

  7. UST_1 stellarator and status of the 3D printed UST_2 stellarator Vicente Queral L 1 UST_1 stellarator and

    E-Print Network [OSTI]

    Columbia University

    UST_1 stellarator and status of the 3D printed UST_2 stellarator Vicente Queral L 1 UST_1 stellarator and Status of the 3D printed UST_2 stellarator Vicente M. Queral* * On leave of absence from NFL and status of the 3D printed UST_2 stellarator Vicente Queral L 2 Background Basic UST_1 and UST_2 data

  8. Modified Finch and Skea stellar model compatible with observational data

    E-Print Network [OSTI]

    D. M. Pandya; V. O. Thomas; R. Sharma

    2014-11-20T23:59:59.000Z

    We present a new class of solutions to the Einstein's field equations corresponding to a static spherically symmetric anisotropic system by generalizing the ansatz of Finch and Skea [Class. Quantum Grav. 6 (1989) 467] for the gravitational potential $g_{rr}$. The anisotropic stellar model previously studied by Sharma and Ratanpal (2013) [Int. J. Mod. Phy. D 13 (2013) 1350074] is a sub-class of the solutions provided here. Based on physical requirements, regularity conditions and stability, we prescribe bounds on the model parameters. By systematically fixing values of the model parameters within the prescribed bound, we demonstrate that our model is compatible with the observed masses and radii of a wide variety of compact stars like 4U 1820-30, PSR J1903+327, 4U 1608-52, Vela X-1, PSR J1614-2230, SAX J1808.4-3658 and Her X-1.

  9. Compact orthogonal NMR field sensor

    DOE Patents [OSTI]

    Gerald, II, Rex E. (Brookfield, IL); Rathke, Jerome W. (Homer Glen, IL)

    2009-02-03T23:59:59.000Z

    A Compact Orthogonal Field Sensor for emitting two orthogonal electro-magnetic fields in a common space. More particularly, a replacement inductor for existing NMR (Nuclear Magnetic Resonance) sensors to allow for NMR imaging. The Compact Orthogonal Field Sensor has a conductive coil and a central conductor electrically connected in series. The central conductor is at least partially surrounded by the coil. The coil and central conductor are electrically or electro-magnetically connected to a device having a means for producing or inducing a current through the coil and central conductor. The Compact Orthogonal Field Sensor can be used in NMR imaging applications to determine the position and the associated NMR spectrum of a sample within the electro-magnetic field of the central conductor.

  10. THE TOP 10 SPITZER YOUNG STELLAR OBJECTS IN 30 DORADUS

    SciTech Connect (OSTI)

    Walborn, Nolan R. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Barba, Rodolfo H. [Departamento de Fisica, Universidad de La Serena, Cisternas 1200 Norte, La Serena (Chile); Sewilo, Marta M., E-mail: walborn@stsci.edu, E-mail: rbarba@dfuls.cl, E-mail: mmsewilo@pha.jhu.edu [Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218 (United States)

    2013-04-15T23:59:59.000Z

    The most luminous Spitzer point sources in the 30 Doradus triggered second generation are investigated coherently in the 3-8 {mu}m region. Remarkable diversity and complexity in their natures are revealed. Some are also among the brightest JHK sources, while others are not. Several of them are multiple when examined at higher angular resolutions with Hubble Space Telescope NICMOS and WFPC2/WFC3 as available, or with VISTA/VMC otherwise. One is a dusty compact H II region near the far northwestern edge of the complex, containing a half-dozen bright I-band sources. Three others appear closely associated with luminous WN stars and causal connections are suggested. Some are in the heads of dust pillars oriented toward R136, as previously discussed from the NICMOS data. One resides in a compact cluster of much fainter sources, while another appears monolithic at the highest resolutions. Surprisingly, one is the brighter of the two extended ''mystery spots'' associated with Knot 2 of Walborn et al. Masses are derived from young stellar object models for unresolved sources and lie in the 10-30 M{sub Sun} range. Further analysis of the IR sources in this unique region will advance understanding of triggered massive star formation, perhaps in some unexpected and unprecedented ways.

  11. Compact monolithic capacitive discharge unit

    DOE Patents [OSTI]

    Roesler, Alexander W. (Tijeras, NM); Vernon, George E. (Rio Rancho, NM); Hoke, Darren A. (Albuquerque, NM); De Marquis, Virginia K. (Tijeras, NM); Harris, Steven M. (Albuquerque, NM)

    2007-06-26T23:59:59.000Z

    A compact monolithic capacitive discharge unit (CDU) is disclosed in which a thyristor switch and a flyback charging circuit are both sandwiched about a ceramic energy storage capacitor. The result is a compact rugged assembly which provides a low-inductance current discharge path. The flyback charging circuit preferably includes a low-temperature co-fired ceramic transformer. The CDU can further include one or more ceramic substrates for enclosing the thyristor switch and for holding various passive components used in the flyback charging circuit. A load such as a detonator can also be attached directly to the CDU.

  12. Compact accelerator for medical therapy

    DOE Patents [OSTI]

    Caporaso, George J.; Chen, Yu-Jiuan; Hawkins, Steven A.; Sampayan, Stephen E.; Paul, Arthur C.

    2010-05-04T23:59:59.000Z

    A compact accelerator system having an integrated particle generator-linear accelerator with a compact, small-scale construction capable of producing an energetic (.about.70-250 MeV) proton beam or other nuclei and transporting the beam direction to a medical therapy patient without the need for bending magnets or other hardware often required for remote beam transport. The integrated particle generator-accelerator is actuable as a unitary body on a support structure to enable scanning of a particle beam by direction actuation of the particle generator-accelerator.

  13. Abundance measurements in stellar environments

    SciTech Connect (OSTI)

    Leone, F. [Università di Catania, Dipartimento di Fisica e Astronomia, Sezione Astrofisica, Via S. Sofia 78, 95123 Catania (Italy)

    2014-05-09T23:59:59.000Z

    Most of what we know about stars, and systems of stars, is derived from the analysis of their electromagnetic radiation. This lesson is an attempt to describe to Physicists, without any Astrophysical background, the framework to understand the present status of abundance determination in stellar environments and its limit. These notes are dedicated to the recently passed, November 21, 2013, Prof. Dimitri Mihalas who spent his life confuting the 19th century positivist philosopher Auguste Comte who stated that we shall not at all be able to determine the chemical composition of stars.

  14. Princeton Plasma Physics Lab - Stellarators

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible forPortsmouth/Paducah47,193.7 348,016.0stellarators Figure-eight shaped tubes that

  15. Stellar populations in bulges of spiral galaxies

    E-Print Network [OSTI]

    P. Jablonka

    1997-03-03T23:59:59.000Z

    We discuss the integrated properties of the stellar population in bulges along the Hubble sequence and new HST data for individual stars in the bulge of M31.

  16. Helical axis stellarator with noninterlocking planar coils

    DOE Patents [OSTI]

    Reiman, Allan (Princeton, NJ); Boozer, Allen H. (Rocky Hill, NJ)

    1987-01-01T23:59:59.000Z

    A helical axis stellarator using only noninterlocking planar, non-circular coils, generates magnetic fields having a magnetic well and large rotational transform with resultant large equilibrium beta.

  17. P.R. Lawson -History of Stellar Interferometry History of Stellar Interferometry

    E-Print Network [OSTI]

    P.R. Lawson - History of Stellar Interferometry History of Stellar Interferometry from 1868 to the present P.R. Lawson Jet Propulsion Laboratory 4 8 0 0 O a k G r o v e D r i v e P a sad e n a , CA 9 1 1 0 9 #12;P.R. Lawson - History of Stellar Interferometry #12;P.R. Lawson - History of Stellar

  18. GENERALIZED ANALYTIC STELLAR STABILITY CRITERIA WITH APPLICATIONS TO LUMINOUS STELLAR ENVELOPES

    E-Print Network [OSTI]

    GENERALIZED ANALYTIC STELLAR STABILITY CRITERIA WITH APPLICATIONS TO LUMINOUS STELLAR ENVELOPES to the outer envelopes of luminous blue variables (LBVs). The acceleration of stellar-wind mass loss has instabilities in luminous blue variables (LBVs), where the acceleration of mass loss becomes significant, even

  19. Mesoscale Simulations of Power Compaction

    SciTech Connect (OSTI)

    Lomov, I; Fujino, D; Antoun, T; Liu, B

    2009-08-06T23:59:59.000Z

    Mesoscale 3D simulations of metal and ceramic powder compaction in shock waves have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating shock compaction of porous well-characterized ductile metal using Steinberg material model. Results of the simulations with handbook values for parameters of solid 2024 aluminum have good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not so well studied as metals, so material model for ceramic (tungsten carbide) has been fitted to shock compression experiments of non-porous samples and further calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powder have been performed and showed good agreement with experimental data. Numerical shock wave profile has same character and thickness as measured with VISAR. Numerical results show reshock states above the single-shock Hugoniot line also observed in experiments. They found that to receive good quantitative agreement with experiment it is essential to perform 3D simulations.

  20. Interstate Oil and Gas Conservation Compact (Montana)

    Broader source: Energy.gov [DOE]

    This legislation authorizes the State to join the Interstate Compact for the Conservation of Oil and Gas. The Compact is an agreement that has been entered into by 30 oil- and gas-producing states,...

  1. Interstate Oil and Gas Conservation Compact (Maryland)

    Broader source: Energy.gov [DOE]

    This legislation authorizes the State to join the Interstate Compact for the Conservation of Oil and Gas. The Compact is an agreement that has been entered into by 30 oil- and gas-producing states,...

  2. The transition from adiabatic inspiral to geodesic plunge for a compact object around a massive Kerr black hole: Generic orbits

    E-Print Network [OSTI]

    Pranesh A. Sundararajan

    2008-05-08T23:59:59.000Z

    The inspiral of a stellar mass compact object falling into a massive Kerr black hole can be broken into three different regimes: An adiabatic inspiral phase, where the inspiral timescale is much larger than the orbital period; a late-time radial infall, which can be approximated as a plunging geodesic; and a regime where the body transitions from the inspiral to plunge. In earlier work, Ori and Thorne have outlined a method to compute the trajectory during this transition for a compact object in a circular, equatorial orbit. We generalize this technique to include inclination and eccentricity.

  3. ATTRACTIVE DESIGN APPROACHES FOR A COMPACT STELLARATOR POWER PLANT A.R. Raffray1

    E-Print Network [OSTI]

    California at San Diego, University of

    or liquid breeder blanket with ferritic steel; and (3) self-cooled flibe blanket with ferritic steel Phase I of the ARIES-CS study, covering the different blanket configurations and maintenance schemes will be used as the basis to down- select to a couple of combinations of blanket configuration and maintenance

  4. BENEFITS OF RADIAL BUILD MINIMIZATION AND REQUIREMENTS IMPOSED ON ARIES COMPACT STELLARATOR DESIGN

    E-Print Network [OSTI]

    field at the coil. During the first phase of the study, several blanket/shield systems have been considered employing advanced ferritic steel (FS) structure (such as IEA MF82H) and SiC/SiC composites-based systems (self-cooled Flibe/FS/Be and LiPb/SiC, and dual-cooled LiPb/FS/He and Li/FS/He). The newly

  5. Robustness and Flexibility in Compact Quasiaxial Stellarators: Global Ideal MHD Stability and Energetic Particle Transport

    E-Print Network [OSTI]

    , making use of advanced computer packages as well as high performance computing platforms. Although

  6. Robustness and flexibility in compact quasiaxial stellarators: Global ideal magnetohydrodynamic stability and energetic particle transport

    E-Print Network [OSTI]

    , making use of advanced computer packages as well as high performance computing platforms. Although

  7. Robustness and Flexibility in Compact Quasiaxial Stellarators: Global Ideal Magnetohydrodynamic Stability and Energetic Particle Transport

    E-Print Network [OSTI]

    Redi, Martha H.

    , making use of advanced computer packages as well as high performance computing platforms. Although

  8. Compact neutron generator development at LBNL

    E-Print Network [OSTI]

    2003-01-01T23:59:59.000Z

    Generator Development at LBNL J. Reijonen, G. English, R.Technology Group in LBNL. The compact axial extraction

  9. Confirmed: Stellar Behemoth Self-Destructs in Type IIb Supernova

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625govInstrumentstdmadapInactiveVisiting theCommercialization andComputerConfirmed: Stellar Behemoth Self-Destructs in

  10. Parallization of Stellar Atmosphere Codes

    E-Print Network [OSTI]

    P. Hoeflich

    2002-09-19T23:59:59.000Z

    Parallel computing has turned out to be the enabling technology to solve complex physical systems. However, the transition from shared memory, vector computers to massively parallel, distributed memory systems and, recently, to hybrid systems poses new challenges to the scientist. We want to present a cook-book (with a very strong, personal bias) based on our experience with parallization of our existing codes. Some of the general tools and communication libraries are discussed. Our approach includes a mixture of algorithm, domain and physical module based parallization. The advantages, scalability and limitations of each are discussed at some examples. We want show that it becomes easier to write parallel code with increasing complexity of the physical problem making stellar atmosphere codes beyond the classical assumptions very suitable.

  11. Stellar Explosions by Magnetic Towers

    E-Print Network [OSTI]

    Dmitri A. Uzdensky; Andrew I. MacFadyen

    2006-05-05T23:59:59.000Z

    We propose a magnetic mechanism for the collimated explosion of a massive star relevant for GRBs, XRFs and asymmetric supernovae. We apply Lynden-Bell's magnetic tower scenario to the interior of a massive rotating star after the core has collapsed to form a black hole with an accretion disk or a millisecond magnetar acting as a central engine. We solve the force-free Grad-Shafranov equation to calculate the magnetic structure and growth of a tower embedded in a stellar environment. The pressure of the toroidal magnetic field, continuously generated by differential rotation of the central engine, drives a rapid expansion which becomes vertically collimated after lateral force balance with the surrounding gas pressure is reached. The collimation naturally occurs because hoop stress concentrates magnetic field toward the rotation axis and inhibits lateral expansion. This leads to the growth of a self-collimated magnetic tower. When embedded in a massive star, the supersonic expansion of the tower drives a strong bow shock behind which an over-pressured cocoon forms. The cocoon confines the tower by supplying collimating pressure and provides stabilization against disruption due to MHD instabilities. Because the tower consists of closed field lines starting and ending on the central engine, mixing of baryons from the cocoon into the tower is suppressed. The channel cleared by the growing tower is thus plausibly free of baryons and allows the escape of magnetic energy from the central engine through the star. While propagating down the stellar density gradient, the tower accelerates and becomes relativistic. During the expansion, fast collisionless reconnection becomes possible resulting in dissipation of magnetic energy which may be responsible for GRB prompt emission.

  12. Proceedings of US-Japan heliotron-stellarator workshop: Volume 3

    SciTech Connect (OSTI)

    Not Available

    1987-01-01T23:59:59.000Z

    This paper is the third of four volumes on the US-Japan Heliotron-Stellarator Workshop. It contains talks on the following: Heliotron EICRF Heating Experiment; CHS Heating Systems (NBI, ECH, ICH); ICH Program for ATF; ICRF Wave Propagation; the HBQM Heliac Work; configuration studies; compact torsatron studies; low aspect ratio torsatron design; optimized small stellarator designs; configuration studies for ATF; currents in ATF; currents in ATF; computations of 3-D equilibria with islands; magnetic surface mapping studies; magnetic field alignment and mapping on ATF; divertor experiments in IMS; PMI program and wall conditioning for ATF; hard X-ray suppression on ATF; plasma rotation and potential measurement; and status of heavy ion beam probe for ATF.

  13. Software Development for a CompactRIO-Based Wire Scanner Control and Data Acquisition SYstem

    SciTech Connect (OSTI)

    Sedillo, James Daniel [Los Alamos National Laboratory

    2012-05-16T23:59:59.000Z

    The Beam Diagnostics and Instrumentation Team at the Los Alamos Neutron Science Center is developing a wire scanner data acquisition and control system with a National Instrument's compactRIO at its core. For this application, the compactRIO controller not only requires programming the FPGA and RT computer internal to the compactRIO, but also requires programming a client computer and a touch panel display. This article will summarize the hardware interfaces and describe the software design approach utilized for programming and interfacing the four systems together in order to fulfill the design requirements and promote reliable interoperability.

  14. The 11 th Cool Stars, Stellar Systems and the Sun ASP Conference Series, Vol. 223, 2001

    E-Print Network [OSTI]

    Linsky, Jeffrey L.

    The 11 th Cool Stars, Stellar Systems and the Sun ASP Conference Series, Vol. 223, 2001 R. J. Garc of telescope time and computing power (i.e. by applying the \\Doppler-imaging" technique). Only National Observatory Lick 3-m Lick Observatory McD 2.1-m McDonald Observatory NOT 2.4-m Nordic Optical

  15. Compact portable diffraction moire interferometer

    DOE Patents [OSTI]

    Deason, Vance A. (Shelley, ID); Ward, Michael B. (Idaho Falls, ID)

    1989-01-01T23:59:59.000Z

    A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observation means including film and video cameras may be used to view and record the resultant fringe patterns.

  16. Compact portable diffraction moire interferometer

    DOE Patents [OSTI]

    Deason, V.A.; Ward, M.B.

    1988-05-23T23:59:59.000Z

    A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observations means including film and video cameras may be used to view and record the resultant fringe patterns. 7 figs.

  17. Compact magnetic energy storage module

    DOE Patents [OSTI]

    Prueitt, Melvin L. (Los Alamos, NM)

    1994-01-01T23:59:59.000Z

    A superconducting compact magnetic energy storage module in which a plurality of superconducting toroids, each having a toroidally wound superconducting winding inside a poloidally wound superconducting winding, are stacked so that the flow of electricity in each toroidally wound superconducting winding is in a direction opposite from the direction of electrical flow in other contiguous superconducting toroids. This allows for minimal magnetic pollution outside of the module.

  18. Compact magnetic energy storage module

    DOE Patents [OSTI]

    Prueitt, M.L.

    1994-12-20T23:59:59.000Z

    A superconducting compact magnetic energy storage module in which a plurality of superconducting toroids, each having a toroidally wound superconducting winding inside a poloidally wound superconducting winding, are stacked so that the flow of electricity in each toroidally wound superconducting winding is in a direction opposite from the direction of electrical flow in other contiguous superconducting toroids. This allows for minimal magnetic pollution outside of the module. 4 figures.

  19. Captures of stars by a massive black hole: Investigations in numerical stellar dynamics

    E-Print Network [OSTI]

    Marc Freitag

    2003-06-03T23:59:59.000Z

    Among the astrophysical systems targeted by LISA, stars on relativistic orbits around massive black holes (MBHs) are particularly promising sources. Unfortunately, the prediction for the number and characteristics of such sources suffers from many uncertainties. Stellar dynamical Monte Carlo simulations of the evolution of galactic nucleus models allow more realistic estimates of these quantities. The computations presented here strongly suggest that the closest such extreme mass-ratio binary to be detected by LISA could be a low-mass MS star (MSS) orbiting the MBH at the center of our Milky Way. Only compact stars contribute to the expected detections from other galaxies because MSSs are disrupted by tidal forces too early.

  20. Electron screening effect on stellar thermonuclear fusion

    E-Print Network [OSTI]

    Potekhin, A Y

    2013-01-01T23:59:59.000Z

    We study the impact of plasma correlation effects on nonresonant thermonuclear reactions for various stellar objects, namely in the liquid envelopes of neutron stars, and the interiors of white dwarfs, low-mass stars, and substellar objects. We examine in particular the effect of electron screening on the enhancement of thermonuclear reactions in dense plasmas within and beyond the linear mixing rule approximation as well as the corrections due to quantum effects at high density. In addition, we examine some recent unconventional (Yukawa-potential and "quantum-tail") theoretical results on stellar thermonuclear fusions and show that these scenarios do not apply to stellar conditions.

  1. Supernova rates and stellar populations

    E-Print Network [OSTI]

    F. Mannucci

    2007-08-03T23:59:59.000Z

    We discuss the results about the nature of type Ia Supernovae that can be derived by studying their rates in different stellar populations. While the evolution of SN photometry and spectra can constrain the explosion mechanism, the SN rate depends on the progenitor system. We review the current available data on rates as a function of parent galaxy color, morphology, star formation rate, radio luminosity and environment. By studying the variation of the rates with the color of the parent galaxy, a strong evidence was established that type Ia SNe come from both young and old stars. The dependence of the rates with the radio power of the parent galaxy is best reproduced by a bimodal distribution of delay time between the formation of the progenitor and its explosion as a SN. Cluster early-type galaxies show higher type Ia SN rate with respect to field galaxies, and this effect can be due either to traces of young stars or to differences in the delay time distribution.

  2. Wind anisotropy and stellar evolution

    E-Print Network [OSTI]

    Cyril Georgy; Georges Meynet; André Maeder

    2008-07-31T23:59:59.000Z

    Mass loss is a determinant factor which strongly affects the evolution and the fate of massive stars. At low metallicity, stars are supposed to rotate faster than at the solar one. This favors the existence of stars near the critical velocity. In this rotation regime, the deformation of the stellar surface becomes important, and wind anisotropy develops. Polar winds are expected to be dominant for fast rotating hot stars. These polar winds allow the star to lose large quantities of mass and still retain a high angular momentum, and they modifie the evolution of the surface velocity and the final angular momentum kept in the star's core. We show here how these winds affect the final stages of massive stars, according to our knowledge about Gamma Ray Bursts. Computation of theoretical Gamma Ray Bursts rate indicates that our models have too fast rotating cores, and that we need to include an additional effect to spin them down. Magnetic fields in stars act in this direction, and we show how they modify the evolution of massive star up to the final stages.

  3. Stellar Populations in Bulges of Spiral Galaxies

    E-Print Network [OSTI]

    P. Jablonka; J. Gorgas; P. Goudfrooij

    2002-02-01T23:59:59.000Z

    We have conducted a spectroscopic analysis of the bulges of a sample of 31 spiral galaxies, spanning the Hubble sequence from S0 to Scd type, in order to study the radial distribution of their stellar population properties.

  4. Two Piece Compaction Die Design

    SciTech Connect (OSTI)

    Coffey, Ethan N [ORNL

    2010-03-01T23:59:59.000Z

    Compaction dies used to create europium oxide and tantalum control plates were modeled using ANSYS 11.0. Two-piece designs were considered in order to make the dies easier to assemble than the five-piece dies that were previously used. The two areas of concern were the stresses at the interior corner of the die cavity and the distortion of the cavity wall due to the interference fit between the two pieces and the pressure exerted on the die during the compaction process. A successful die design would have stresses less than the yield stress of the material and a maximum wall distortion on the order of 0.0001 in. Design factors that were investigated include the inner corner radius, the value of the interference fit, the compaction force, the size of the cavity, and the outer radius and geometry of the outer ring. The results show that for the europium oxide die, a 0.01 in. diameter wire can be used to create the cavity, leading to a 0.0055 in. radius corner, if the radial interference fit is 0.003 in. For the tantalum die, the same wire can be used with a radial interference fit of 0.001 in. Also, for the europium oxide die with a 0.003 in. interference fit, it is possible to use a wire with a diameter of 0.006 in. for the wire burning process. Adding a 10% safety factor to the compaction force tends to lead to conservative estimates of the stresses but not for the wall distortion. However, when the 10% safety factor is removed, the wall distortion is not affected enough to discard the design. Finally, regarding the europium oxide die, when the cavity walls are increased by 0.002 in. per side or the outer ring is made to the same geometry as the tantalum die, all the stresses and wall distortions are within the desired range. Thus, the recommendation is to use a 0.006 in. diameter wire and a 0.003 in. interference fit for the europium oxide die and a 0.01 in. diameter wire and a 0.001 in. interference fit for the tantalum die. The dies can also be made to have the same outer geometry if desired.

  5. Compacted carbon for electrochemical cells

    DOE Patents [OSTI]

    Greinke, R.A.; Lewis, I.C.

    1997-10-14T23:59:59.000Z

    This invention provides compacted carbon that is useful in the electrode of an alkali metal/carbon electrochemical cell of improved capacity selected from the group consisting of: (a) coke having the following properties: (1) an x-ray density of at least 2.00 grams per cubic centimeters, (2) a closed porosity of no greater than 5%, and (3) an open porosity of no greater than 47%; and (b) graphite having the following properties: (1) an x-ray density of at least 2.20 grams per cubic centimeters, (2) a closed porosity of no greater than 5%, and (3) an open porosity of no greater than 25%. This invention also relates to an electrode for an alkali metal/carbon electrochemical cell comprising compacted carbon as described above and a binder. This invention further provides an alkali metal/carbon electrochemical cell comprising: (a) an electrode as described above, (b) a non-aqueous electrolytic solution comprising an organic aprotic solvent and an electrolytically conductive salt and an alkali metal, and (c) a counter electrode. 10 figs.

  6. Compact submanifolds supporting singular interactions

    SciTech Connect (OSTI)

    Kaynak, Burak Tevfik, E-mail: burak.kaynak@boun.edu.tr; Teoman Turgut, O., E-mail: turgutte@boun.edu.tr

    2013-12-15T23:59:59.000Z

    A quantum particle moving under the influence of singular interactions on embedded surfaces furnish an interesting example from the spectral point of view. In these problems, the possible occurrence of a bound-state is perhaps the most important aspect. Such systems can be introduced as quadratic forms and generically they do not require renormalization. Yet an alternative path through the resolvent is also beneficial to study various properties. In the present work, we address these issues for compact surfaces embedded in a class of ambient manifolds. We discover that there is an exact bound state solution written in terms of the heat kernel of the ambient manifold for a range of coupling strengths. Moreover, we develop techniques to estimate bounds on the ground state energy when several surfaces, each of which admits a bound state solution, coexist. -- Highlights: •Schrödinger operator with singular interactions supported on compact submanifolds. •Exact bound-state solution in terms of the heat kernel of the ambient manifold. •Generalization of the variational approach to a collection of submanifolds. •Existence of a lower bound for a unique ground state energy.

  7. Hydrostatic compaction of Microtherm HT.

    SciTech Connect (OSTI)

    Broome, Scott Thomas; Bauer, Stephen J.

    2010-09-01T23:59:59.000Z

    Two samples of jacketed Microtherm{reg_sign}HT were hydrostatically pressurized to maximum pressures of 29,000 psi to evaluate both pressure-volume response and change in bulk modulus as a function of density. During testing, each of the two samples exhibited large irreversible compactive volumetric strains with only small increases in pressure; however at volumetric strains of approximately 50%, the Microtherm{reg_sign}HT stiffened noticeably at ever increasing rates. At the maximum pressure of 29,000 psi, the volumetric strains for both samples were approximately 70%. Bulk modulus, as determined from hydrostatic unload/reload loops, increased by more than two-orders of magnitude (from about 4500 psi to over 500,000 psi) from an initial material density of {approx}0.3 g/cc to a final density of {approx}1.1 g/cc. An empirical fit to the density vs. bulk modulus data is K = 492769{rho}{sup 4.6548}, where K is the bulk modulus in psi, and {rho} is the material density in g/cm{sup 3}. The porosity decreased from 88% to {approx}20% indicating that much higher pressures would be required to compact the material fully.

  8. Compact approach to fusion power reactors

    SciTech Connect (OSTI)

    Hagenson, R.L.; Krakowski, R.A.; Bathke, C.G.; Miller, R.L.

    1984-01-01T23:59:59.000Z

    The potential of the Reversed-Field Pinch (RFP) for development into an efficient, compact, copper-coil fusion reactor has been quantified by comprehensive parametric tradeoff studies. These compact systems promise to be competitive in size, power density, and cost to alternative energy sources. Conceptual engineering designs that largely substantiate these promising results have since been completed. This 1000-MWe(net) design is described along with a detailed rationale and physics/technology assessment for the compact approach to fusion.

  9. Method for preparing porous metal hydride compacts

    DOE Patents [OSTI]

    Ron, M.; Gruen, D.M.; Mendelsohn, M.H.; Sheft, I.

    1980-01-21T23:59:59.000Z

    A method for preparing porous metallic-matrix hydride compacts which can be repeatedly hydrided and dehydrided without disintegration. A mixture of a finely divided metal hydride and a finely divided matrix metal is contacted with a poison which prevents the metal hydride from dehydriding at room temperature and atmospheric pressure. The mixture of matrix metal and poisoned metal hydride is then compacted under pressure at room temperature to form porous metallic-matrix hydride compacts.

  10. Method for preparing porous metal hydride compacts

    DOE Patents [OSTI]

    Ron, Moshe (Haifa, IL); Gruen, Dieter M. (Downers Grove, IL); Mendelsohn, Marshall H. (Woodridge, IL); Sheft, Irving (Oak Park, IL)

    1981-01-01T23:59:59.000Z

    A method for preparing porous metallic-matrix hydride compacts which can be repeatedly hydrided and dehydrided without disintegration. A mixture of a finely divided metal hydride and a finely divided matrix metal is contacted with a poison which prevents the metal hydride from dehydriding at room temperature and atmospheric pressure. The mixture of matrix metal and poisoned metal hydride is then compacted under pressure at room temperature to form porous metallic-matrix hydride compacts.

  11. Convolution type operators on locally compact groups

    E-Print Network [OSTI]

    Shtein--~erg, Convolution Type Operators on Locally Compact Groups [in Russian],. Manuscript Deposited in the All-Union Institute of Scientific and Technical ...

  12. Covered Product Category: Compact Fluorescent Lamps

    Broader source: Energy.gov [DOE]

    FEMP provides acquisition guidance across a variety of product categories, including compact fluorescent lamps (CFLs), which are an ENERGY STAR-qualified product category.

  13. Interstate Mining Compact Commission (multi-state)

    Broader source: Energy.gov [DOE]

    The Interstate Mining Compact is a multi-state governmental agency / organization that represents the natural resource and related environmental protection interests of its member states. Currently...

  14. Compact Solid State Cooling Systems: Compact MEMS Electrocaloric Module

    SciTech Connect (OSTI)

    None

    2010-10-01T23:59:59.000Z

    BEETIT Project: UCLA is developing a novel solid-state cooling technology to translate a recent scientific discovery of the so-called giant electrocaloric effect into commercially viable compact cooling systems. Traditional air conditioners use noisy, vapor compression systems that include a polluting liquid refrigerant to circulate within the air conditioner, absorb heat, and pump the heat out into the environment. Electrocaloric materials achieve the same result by heating up when placed within an electric field and cooling down when removed—effectively pumping heat out from a cooler to warmer environment. This electrocaloric-based solid state cooling system is quiet and does not use liquid refrigerants. The innovation includes developing nano-structured materials and reliable interfaces for heat exchange. With these innovations and advances in micro/nano-scale manufacturing technologies pioneered by semiconductor companies, UCLA is aiming to extend the performance/reliability of the cooling module.

  15. Phased array compaction cell for measurement of the transversely isotropic elastic properties of compacting sediments

    E-Print Network [OSTI]

    Nihei, K.T.

    2012-01-01T23:59:59.000Z

    compaction and chemical diagenesis on the microfabric andAt early stages of diagenesis, clay-rich sediments can

  16. Gravitational Waves from Stellar Collapse: Correlations to Explosion Asymmetries

    E-Print Network [OSTI]

    Chris L. Fryer; Daniel E. Holz; Scott A. Hughes

    2004-03-08T23:59:59.000Z

    The collapse of massive stars not only produces observable outbursts across the entire electromagnetic spectrum but, for Galactic (or near-Galactic) supernovae, detectable signals for ground-based neutrino and gravitational wave detectors. Gravitational waves and neutrinos provide the only means to study the actual engine behind the optical outbursts: the collapsed stellar core. While the neutrinos are most sensitive to details of the equation of state, gravitational waves provide a means to study the mass asymmetries in this central core. We present gravitational wave signals from a series of 3-dimensional core-collapse simulations with asymmetries derived from initial perturbations caused by pre-collapse convection, core rotation, and low-mode convection in the explosion engine itself. A Galactic supernovae will allow us to differentiate these different sources of asymmetry. Combining this signal with other observations of the supernova, from neutrinos to gamma-rays to the compact remnant, dramatically increases the predictive power of the gravitational wave signal. We conclude with a discussion of the gravitational wave signal arising from collapsars, the leading engine for long-duration gamma-ray bursts.

  17. SCORPIO: A deep survey of Radio Emission from the stellar life-cycle

    E-Print Network [OSTI]

    Umana, G; Franzen, T M O; Norris, R P; Leto, P; Ingallinera, A; Buemi, C S; Agliozzo, C; Cavallaro, F; Cerrigone, L

    2015-01-01T23:59:59.000Z

    Radio emission has been detected in a broad variety of stellar objects from all stages of stellar evolution. However, most of our knowledge originates from targeted observations of small samples, which are strongly biased to sources which are peculiar at other wavelengths. In order to tackle this problem we have conducted a deep 1.4 GHz survey by using the Australian Telescope Compact Array (ATCA), following the same observing setup as that used for the Australia Telescope Large Area Survey (ATLAS) project, this time choosing a region more appropriate for stellar work. In this paper, the SCORPIO project is presented as well as results from the pilot experiment. The achieved rms is about 30 /uJy and the angular resolution ~10 arcsec. About six hundred of point-like sources have been extracted just from the pilot field. A very small percentage of them are classified in SIMBAD or the NASA/IPAC Extragalactic Database (NED). About 80 % of the extracted sources are reported in one of the inspected catalogues and 50...

  18. Compact Orthogonal NMR Field Sensor - Energy Innovation Portal

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville Power Administration would like submit the followingth Lomonosov1 COMMUNITYGeothermalCompact

  19. Compact high resolution isobar separator for study of exotic decays

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville Power Administration would like submit the followingth Lomonosov1Compact high resolution isobar

  20. Cooling of Color Superconducting Compact Stars

    E-Print Network [OSTI]

    David Blaschke

    2006-03-26T23:59:59.000Z

    We review the status of research on the cooling of compact stars, with emphasis on the influence of color superconducting quark matter phases. Although a consistent microscopic approach is not yet available, severe constraints on the phase structure of matter at high densities come from recent mass and cooling observations of compact stars.

  1. The Compressor: Concurrent, Incremental, and Parallel Compaction

    E-Print Network [OSTI]

    Petrank, Erez

    The Compressor: Concurrent, Incremental, and Parallel Compaction Haim Kermany Erez Petrank Dept non-intrusive compactor is still missing. In this paper we present the Compressor, a novel compaction, thereby allowing acceptable runs on large heaps. Furthermore, the Compressor is the first compactor

  2. Compacted Soil Liner Interface Strength Importance

    E-Print Network [OSTI]

    Case Study Compacted Soil Liner Interface Strength Importance Timothy D. Stark, F.ASCE1 ; Hangseok interface is not the geomembrane (GM)/compacted low-permeability soil liner (LPSL) but a soil­soil interface placing the cover soil from bottom to top. DOI: 10.1061/(ASCE)GT.1943-5606 .0000556. © 2012 American

  3. Why Python? 1) readable, compact, simple syntax

    E-Print Network [OSTI]

    Spang, Rainer

    Starting with Python #12;Why Python? 1) readable, compact, simple syntax 2) documented 3) memory output shown using green text 5 True 27 10/19/2010 6 #12;Scope · Declarations are global · Cannot for usually compacter, while more general. for - doing X for each element of S. can simulate while loops

  4. Non-compact versions of Edwards' Theorem

    E-Print Network [OSTI]

    Gogus, Nihat G; Poletsky, Evgeny A

    2010-01-01T23:59:59.000Z

    Edwards' Theorem establishes duality between a convex cone in the space of continuous functions on a compact space and the set of representing or Jensen measures for this cone. In this paper we prove non-compact versions of this theorem.

  5. Keck-I MOSFIRE spectroscopy of compact star-forming galaxies at z$\\gtrsim$2: High velocity dispersions in progenitors of compact quiescent galaxies

    E-Print Network [OSTI]

    Barro, G; Koo, D C; Dekel, A; Kassin, S A; Kocevski, D D; Faber, S M; van der Wel, A; Guo, Y; Perez-Gonzalez, P G; Toloba, E; Fang, J J; Pacifici, C; Simons, R; Campbell, R D; Ceverino, D; Finkelstein, S L; Goodrich, B; Kassis, M; Koekemoer, A M; Konidaris, N P; Livermore, R C; Lyke, J E; Mobasher, B; Nayyeri, H; Peth, M; Primack, J R; Rizzi, L; Somerville, R S; Wirth, G D; Zolotov, A

    2014-01-01T23:59:59.000Z

    We present Keck-I MOSFIRE near-infrared spectroscopy for a sample of 13 compact star-forming galaxies (SFGs) at redshift $2\\leq z \\leq2.5$ with star formation rates of SFR$\\sim$100M$_{\\odot}$ y$^{-1}$ and masses of log(M/M$_{\\odot}$)$\\sim10.8$. Their high integrated gas velocity dispersions of $\\sigma_{\\rm{int}}$=230$^{+40}_{-30}$ km s$^{-1}$, as measured from emission lines of H$_{\\alpha}$ and [OIII], and the resultant M$_{\\star}-\\sigma_{\\rm{int}}$ relation and M$_{\\star}$$-$M$_{\\rm{dyn}}$ all match well to those of compact quiescent galaxies at $z\\sim2$, as measured from stellar absorption lines. Since log(M$_{\\star}$/M$_{\\rm{dyn}}$)$=-0.06\\pm0.2$ dex, these compact SFGs appear to be dynamically relaxed and more evolved, i.e., more depleted in gas and dark matter ($infusion of external gas, depletion timescales are short, less than $\\sim$300 Myr. This discovery adds another link to our new dynamical chain of evidence...

  6. Stellarators | Princeton Plasma Physics Lab

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del Sol HomeFacebookScholarshipSpiraling LaserAppropriations

  7. Recent advances in modeling stellar interiors (u)

    SciTech Connect (OSTI)

    Guzik, Joyce Ann [Los Alamos National Laboratory

    2010-01-01T23:59:59.000Z

    Advances in stellar interior modeling are being driven by new data from large-scale surveys and high-precision photometric and spectroscopic observations. Here we focus on single stars in normal evolutionary phases; we will not discuss the many advances in modeling star formation, interacting binaries, supernovae, or neutron stars. We review briefly: (1) updates to input physics of stellar models; (2) progress in two and three-dimensional evolution and hydrodynamic models; (3) insights from oscillation data used to infer stellar interior structure and validate model predictions (asteroseismology). We close by highlighting a few outstanding problems, e.g., the driving mechanisms for hybrid {gamma} Dor/{delta} Sct star pulsations, the cause of giant eruptions seen in luminous blue variables such as {eta} Car and P Cyg, and the solar abundance problem.

  8. Stellar abundances of beryllium and CUBES

    E-Print Network [OSTI]

    Smiljanic, R

    2014-01-01T23:59:59.000Z

    Stellar abundances of beryllium are useful in different areas of astrophysics, including studies of the Galactic chemical evolution, of stellar evolution, and of the formation of globular clusters. Determining Be abundances in stars is, however, a challenging endeavor. The two Be II resonance lines useful for abundance analyses are in the near UV, a region strongly affected by atmospheric extinction. CUBES is a new spectrograph planned for the VLT that will be more sensitive than current instruments in the near UV spectral region. It will allow the observation of fainter stars, expanding the number of targets where Be abundances can be determined. Here, a brief review of stellar abundances of Be is presented together with a discussion of science cases for CUBES. In particular, preliminary simulations of CUBES spectra are presented, highlighting its possible impact in investigations of Be abundances of extremely metal-poor stars and of stars in globular clusters.

  9. Electron capture cross sections for stellar nucleosynthesis

    E-Print Network [OSTI]

    Giannaka, P G

    2015-01-01T23:59:59.000Z

    In the first stage of this work, we perform detailed calculations for the cross sections of the electron capture on nuclei under laboratory conditions. Towards this aim we exploit the advantages of a refined version of the proton-neutron quasi-particle random-phase approximation (pn-QRPA) and carry out state-by-state evaluations of the rates of exclusive processes that lead to any of the accessible transitions within the chosen model space. In the second stage of our present study, we translate the above mentioned $e^-$-capture cross sections to the stellar environment ones by inserting the temperature dependence through a Maxwell-Boltzmann distribution describing the stellar electron gas. As a concrete nuclear target we use the $^{66}Zn$ isotope, which belongs to the iron group nuclei and plays prominent role in stellar nucleosynthesis at core collapse supernovae environment.

  10. Stellar Populations in Circumnuclear Star Forming Regions

    E-Print Network [OSTI]

    A. I. Diaz; M. Alvarez-Alvarez; M. Castellanos

    2002-05-07T23:59:59.000Z

    We present a study of the stellar populations and gas physical conditions in Circumnuclear Star Forming Regions (CNSFR) based on broad and narrow band photometry and spectrophotometric data, which have been analyzed with the use of evolutionary population synthesis and photoionization models. It is found that most CNSFR show composite stellar populations of slightly different ages. They seem to have the highest abundances in HII region-like objects, showing also N/O overabundances and S/O underabundances by a factor of about three. Also, CNSFR as a class, segregate from the disk HII region family, clustering around smaller $\\eta$' values, and thereforefore higher ionizing temperatures.

  11. Ultra-Compact H II Regions and the Early Lives of Massive Stars

    E-Print Network [OSTI]

    M. G. Hoare; S. E. Kurtz; S. Lizano; E. Keto; P. Hofner

    2006-03-21T23:59:59.000Z

    We review the phenomenon of ultra-compact H II regions (UCHIIs) as a key phase in the early lives of massive stars. This most visible manifestation of massive star formation begins when the Lyman continuum output from the massive young stellar object becomes sufficient to ionize the surroundings from which it was born. Knowledge of this environment is gained through an understanding of the morphologies of UCHII regions and we examine the latest developments in deep radio and mid-IR imaging. SPITZER data from the GLIMPSE survey are an important new resource in which PAH emission and the ionizing stars can be seen. We review the role played by strong stellar winds from the central stars in sweeping out central cavities and causing the limb-brightened appearance. A range of evidence from velocity structure, proper motions, the molecular environment and recent hydrodynamical modeling indicates that cometary UCHII regions require a combination of champagne flow and bow shock motion. Finally, we discuss the class of hyper-compact H II regions or broad recombination line objects. They are likely to mark the transition soon after the breakout of the Lyman continuum radiation from the young star. Models for these objects are presented, including photo-evaporating disks and ionized accretion flows that are gravitationally trapped. Evolutionary scenarios tracing young massive stars passage through these ionized phases are discussed.

  12. Compacting Plastic-Bonded Explosive Molding Powders to Dense Solids

    SciTech Connect (OSTI)

    B. Olinger

    2005-04-15T23:59:59.000Z

    Dense solid high explosives are made by compacting plastic-bonded explosive molding powders with high pressures and temperatures for extended periods of time. The density is influenced by manufacturing processes of the powders, compaction temperature, the magnitude of compaction pressure, pressure duration, and number of repeated applications of pressure. The internal density variation of compacted explosives depends on method of compaction and the material being compacted.

  13. From Ultracompact to Extended HII Regions. II: Cloud Gravity and Stellar Motion

    E-Print Network [OSTI]

    Jose Franco; Guillermo Garcia-Segura; Stan Kurtz

    2005-08-22T23:59:59.000Z

    The dynamical evolution of HII regions with and without stellar motion in dense, structured molecular clouds is studied. Clouds are modeled in hydrostatic equilibrium, with gaussian central cores and external halos that obey r**-2 and r**-3 density power laws. The cloud gravity is included as a time-independent, external force. Stellar velocities of 0, 2, 8, and 12 km/s are considered. When stellar motion is included, stars move from the central core to the edge of the cloud, producing transitions from ultracompact to extended HII regions as the stars move into lower density regions. The opposite behavior occurs when stars move toward the cloud cores. The main conclusion of our study is that ultracompact HII regions are pressure-confined entities while they remain embedded within dense cores. The confinement comes from ram and/or ambient pressures. The survival of ultracompact regions depends on the position of the star with respect to the core, the stellar life-time, and the core crossing time. Stars with velocities less than the cloud dispersion velocity can produce cometary shapes smaller than 0.1 pc at times of 20,000 yr or more. The sequence Ultracompact to Compact to Extended HII region shows a variety of unpredictable structures due to ionization-shock front instability. Some ultracompact HII regions with a core-halo morphology might be explained by self-blocking effects, when stars overtake and ionize leading, piled-up clumps of neutral gas. We use thermal energy to support the cloud against gravity; the results remain the same if other types of isotropic cloud support are used.

  14. Compact, electro-hydraulic, variable valve actuation system providing...

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

    Compact, electro-hydraulic, variable valve actuation system providing variable lift, timing and duration to enable high efficiency engine combustion control Compact,...

  15. A compact tritium AMS system

    SciTech Connect (OSTI)

    Chiarappa, M L; Dingley, K H; Hamm, R W; Love, A H; Roberts, M L

    1999-09-23T23:59:59.000Z

    Tritium ({sup 3}H) is a radioisotope that is extensively utilized in biological and environmental research. For biological research, {sup 3}H is generally quantified by liquid scintillation counting requiring gram-sized samples and counting times of several hours. For environmental research, {sup 3}H is usually quantified by {sup 3}He in-growth which requires gram-sized samples and in-growth times of several months. In contrast, provisional studies at LLNL's Center for Accelerator Mass Spectrometry have demonstrated that Accelerator Mass Spectrometry (AMS) can be used to quantify {sup 3}H in milligram-sized biological samples with a 100 to 1000-fold improvement in detection limits when compared to scintillation counting. This increased sensitivity is expected to have great impact in the biological and environmental research community. However in order to make the {sup 3}H AMS technique more broadly accessible, smaller, simpler, and less expensive AMS instrumentation must be developed. To meet this need, a compact, relatively low cost prototype {sup 3}H AMS system has been designed and built based on a LLNL ion source/sample changer and an AccSys Technology, Inc. Radio Frequency Quadrupole (RFQ) linac. With the prototype system, {sup 3}/{sup 1}H ratios ranging from 1 x 10{sup -10} to 1 x 10{sup -13} have to be measured from milligram sized samples. With improvements in system operation and sample preparation methodology, the sensitivity limit of the system is expected to increase to approximately 1 x 10{sup -15}.

  16. Transport analysis of a small stellarator

    SciTech Connect (OSTI)

    Kuo-Petravic, G.; Boozer, A.H.

    1983-09-01T23:59:59.000Z

    A Monte Carlo method of evaluating typical particle and energy transport coefficients is given for the case in which the particle drift orbits are a significant fraction of the plasma radius. The method is applied to a preliminary design for a helical axis (heliac) stellarator experiment.

  17. NUCLEAR ASPECTS OF STELLAR AND EXPLOSIVE NUCLEOSYNTHESIS

    E-Print Network [OSTI]

    Rauscher, Thomas

    NUCLEAR ASPECTS OF STELLAR AND EXPLOSIVE NUCLEOSYNTHESIS Thomas Rauscher 1 , Friedrich. of Astron. and Astroph., Univ. of California, Santa Cruz, CA 95064 Abstract The majority of nuclear­Feshbach). The global parametrizations of the nuclear properties needed for predictions far off stability probe our

  18. EXPLORING THE MORPHOLOGY OF RAVE STELLAR SPECTRA

    SciTech Connect (OSTI)

    Matijevic, G.; Zwitter, T. [Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia); Bienayme, O.; Siebert, A. [Observatoire de Strasbourg, Universite de Strasbourg, CNRS, 11 rue de l'universite, 67000 Strasbourg (France); Bland-Hawthorn, J. [Sydney Institute for Astronomy, University of Sydney, NSW 2006 (Australia); Boeche, C.; Grebel, E. K. [Astronomisches Rechen-Institut, Zentrum fuer Astronomie der Universitaet Heidelberg, Moenchhofstr. 12-14, 69120 Heidelberg (Germany); Freeman, K. C. [Research School of Astronomy and Astrophysics, Australia National University, Weston Creek, Canberra, ACT 2611 (Australia); Gibson, B. K. [Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 3TE (United Kingdom); Gilmore, G. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Helmi, A. [Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen (Netherlands); Munari, U. [INAF Osservatorio Astronomico di Padova, 36012 Asiago (Italy); Navarro, J. [Department of Physics and Astronomy, University of Victoria, Victora, BC V8P 5C2 (Canada); Parker, Q. A.; Reid, W. [Department of Physics and Astronomy, Macquarie University, NSW 2109 (Australia); Seabroke, G. [Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking RH5 6NT (United Kingdom); Siviero, A. [Department of Astronomy, Padova University, Vicolo dell'Osservatorio 2, 35122 Padova (Italy); Steinmetz, M.; Williams, M. [Leibniz-Institut fuer Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam (Germany); Watson, F. G., E-mail: gal.matijevic@fmf.uni-lj.si [Australian Astronomical Observatory, P.O. Box 296, Epping, NSW 2121 (Australia); and others

    2012-06-01T23:59:59.000Z

    The RAdial Velocity Experiment (RAVE) is a medium-resolution (R {approx} 7500) spectroscopic survey of the Milky Way that has already obtained over half a million stellar spectra. They present a randomly selected magnitude-limited sample, so it is important to use a reliable and automated classification scheme that identifies normal single stars and discovers different types of peculiar stars. To this end, we present a morphological classification of {approx}350, 000 RAVE survey stellar spectra using locally linear embedding, a dimensionality reduction method that enables representing the complex spectral morphology in a low-dimensional projected space while still preserving the properties of the local neighborhoods of spectra. We find that the majority of all spectra in the database ({approx} 90%-95%) belong to normal single stars, but there is also a significant population of several types of peculiars. Among them, the most populated groups are those of various types of spectroscopic binary and chromospherically active stars. Both of them include several thousands of spectra. Particularly the latter group offers significant further investigation opportunities since activity of stars is a known proxy of stellar ages. Applying the same classification procedure to the sample of normal single stars alone shows that the shape of the projected manifold in two-dimensional space correlates with stellar temperature, surface gravity, and metallicity.

  19. Helical axis stellarator with noninterlocking planar coils

    DOE Patents [OSTI]

    Reiman, A.; Boozer, A.H.

    1984-03-06T23:59:59.000Z

    The present invention generates stellarator fields having favorable properties (magnetic well and large rotational transform) by a simple coil system consisting only of unlinked planar non-circular coils. At large rotational transform toroidal effects on magnetic well and rotational transform are small and can be ignored. We do so herein, specializing in straight helical systems.

  20. Black holes in young stellar clusters

    SciTech Connect (OSTI)

    Goswami, Sanghamitra; Kiel, Paul; Rasio, Frederic A. [Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States)

    2014-02-01T23:59:59.000Z

    We present theoretical models for stellar black hole (BH) properties in young, massive star clusters. Using a Monte Carlo code for stellar dynamics, we model realistic star clusters with N ? 5 × 10{sup 5} stars and significant binary fractions (up to 50%) with self-consistent treatments of stellar dynamics and stellar evolution. We compute the formation rates and characteristic properties of single and binary BHs for various representative ages, cluster parameters, and metallicities. Because of dynamical interactions and supernova (SN) kicks, more single BHs end up retained in clusters compared to BHs in binaries. We also find that the ejection of BHs from a cluster is a strong function of initial density. In low-density clusters (where dynamical effects are negligible), it is mainly SN kicks that eject BHs from the cluster, whereas in high-density clusters (initial central density ? {sub c}(0) ? 10{sup 5} M {sub ?} pc{sup –3} in our models) the BH ejection rate is enhanced significantly by dynamics. Dynamical interactions of binary systems in dense clusters also modify the orbital period and eccentricity distributions while increasing the probability of a BH having a more massive companion.

  1. The Atlas3D Project - XXX. Star formation histories and stellar population scaling relations of early-type galaxies

    E-Print Network [OSTI]

    McDermid, Richard M; Blitz, Leo; Bournaud, Frederic; Bureau, Martin; Cappellari, Michele; Crocker, Alison F; Davies, Roger L; Davis, Timothy A; de Zeeuw, P T; Duc, Pierre-Alain; Emsellem, Eric; Khochfar, Sadegh; Krajnovic, Davor; Kuntschner, Harald; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Scott, Nicholas; Serra, Paolo; Weijmans, Anne-Marie; Young, Lisa M

    2015-01-01T23:59:59.000Z

    We present the stellar population content of early-type galaxies from the Atlas3D survey. Using spectra integrated within apertures covering up to one effective radius, we apply two methods: one based on measuring line-strength indices and applying single stellar population (SSP) models to derive SSP-equivalent values of stellar age, metallicity, and alpha enhancement; and one based on spectral fitting to derive non-parametric star-formation histories, mass-weighted average values of age, metallicity, and half-mass formation timescales. Using homogeneously derived effective radii and dynamically-determined galaxy masses, we present the distribution of stellar population parameters on the Mass Plane (M_JAM, Sigma_e, R_maj), showing that at fixed mass, compact early-type galaxies are on average older, more metal-rich, and more alpha-enhanced than their larger counterparts. From non-parametric star-formation histories, we find that the duration of star formation is systematically more extended in lower mass obje...

  2. TeV neutrinos from microquasars in compact massive binaries

    E-Print Network [OSTI]

    W. Bednarek

    2005-05-27T23:59:59.000Z

    We consider a compact binary system in which a Wolf-Rayet star supplies matter onto a stellar mass black hole or a neutron star. This matter forms an accretion disk which ejects a jet as observed in Galactic microquasars. A part of the jet kinetic energy, typically 10%, can be transfered to relativistic nuclei. These nuclei lose nucleons as a result of photo-disintegration process in collisions with thermal photons from the accretion disk and the massive star. Due to the head on photon-nucleus collisions most of neutrons released from nuclei move towards the surface of the accretion disk and/or the massive star producing neutrinos in collisions with the matter. We calculate the spectra of muon neutrinos and expected neutrino event rates in a 1 km^2 neutrino detector of the IceCube type from a microquasar inside our Galaxy applying, as an example, the parameters of the Cyg X-3 binary system, provided that nuclei are accelerated to the Lorentz factors above 10^6 with the power law spectrum with an index close to 2.

  3. Heart of Darkness: dust obscuration of the central stellar component in globular clusters younger than ~100Myr in multiple stellar population models

    E-Print Network [OSTI]

    Longmore, Steven N

    2015-01-01T23:59:59.000Z

    To explain the observed anomalies in stellar populations within globular clusters, many globular cluster formation theories require two independent episodes of star formation. A fundamental prediction of these models is that the clusters must accumulate large gas reservoirs as the raw material to form the second stellar generation. We show that young clusters containing the required gas reservoir should exhibit the following observational signatures: (i) a dip in the measured luminosity profile or an increase in measured reddening towards the cluster centre, with Av >10mag within a radius of a few pc; (ii) bright (sub)mm emission from dust grains; (iii) bright molecular line emission once the gas is dense enough to begin forming stars. Unless the IMF is anomalously skewed towards low-mass stars, the clusters should also show obvious signs of star formation via optical emission lines (e.g. H_alpha) after the stars have formed. These observational signatures should be readily observable towards any compact clus...

  4. HIERARCHICAL STRUCTURE FORMATION AND MODES OF STAR FORMATION IN HICKSON COMPACT GROUP 31

    SciTech Connect (OSTI)

    Gallagher, S. C. [Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada); Durrell, P. R. [Department of Physics and Astronomy, Youngstown State University, Youngstown, OH 44555 (United States); Elmegreen, D. M. [Department of Physics and Astronomy, Vassar College, Poughkeepsie, NY 12604 (United States); Chandar, R. [Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606-3390 (United States); English, J. [Department of Physics and Astronomy, University of Manitoba, Winnipeg, MN R3T 2N2 (Canada); Charlton, J. C.; Gronwall, C.; Young, J. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Tzanavaris, P.; Hornschemeier, A. E. [Laboratory for X-ray Astrophysics, NASA's Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Johnson, K. E. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States); Mendes de Oliveira, C. [Instituto de Astronomia, Geofisica, e Ciencias Atmosfericas da Universidade de Sao Paulo, Sao Paulo (Brazil); Whitmore, B.; Maybhate, Aparna [Space Telescope Science Institute, Baltimore, MD 21218-2463 (United States); Zabludoff, Ann [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)], E-mail: sgalla4@uwo.ca

    2010-02-15T23:59:59.000Z

    The handful of low-mass, late-type galaxies that comprise Hickson Compact Group 31 (HCG 31) is in the midst of complex, ongoing gravitational interactions, evocative of the process of hierarchical structure formation at higher redshifts. With sensitive, multicolor Hubble Space Telescope imaging, we characterize the large population of < 10 Myr old star clusters (SCs) that suffuse the system. From the colors and luminosities of the young SCs, we find that the galaxies in HCG 31 follow the same universal scaling relations as actively star-forming galaxies in the local universe despite the unusual compact group environment. Furthermore, the specific frequency of the globular cluster system is consistent with the low end of galaxies of comparable masses locally. This, combined with the large mass of neutral hydrogen and tight constraints on the amount of intragroup light, indicate that the group is undergoing its first epoch of interaction-induced star formation. In both the main galaxies and the tidal-dwarf candidate, F, stellar complexes, which are sensitive to the magnitude of disk turbulence, have both sizes and masses more characteristic of z = 1-2 galaxies. After subtracting the light from compact sources, we find no evidence for an underlying old stellar population in F-it appears to be a truly new structure. The low-velocity dispersion of the system components, available reservoir of H I, and current star formation rate of {approx}10 M {sub sun} yr{sup -1} indicate that HCG 31 is likely to both exhaust its cold gas supply and merge within {approx}1 Gyr. We conclude that the end product will be an isolated, X-ray-faint, low-mass elliptical.

  5. INSIDE OUT AND UPSIDE DOWN: TRACING THE ASSEMBLY OF A SIMULATED DISK GALAXY USING MONO-AGE STELLAR POPULATIONS

    SciTech Connect (OSTI)

    Bird, Jonathan C.; Kazantzidis, Stelios; Weinberg, David H. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Guedes, Javiera [Institute for Astronomy, ETH Zuerich, Wolgang-Pauli-Strasse 27, CH-8093 Zuerich (Switzerland); Callegari, Simone [Anthropology Institute and Museum, University of Zuerich, Winterthurerstrasse 190, CH-8057 Zuerich (Switzerland); Mayer, Lucio [Institute for Theoretical Physics, University of Zuerich, Winterthurerstrasse 190, CH-8057 Zuerich (Switzerland); Madau, Piero [Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)

    2013-08-10T23:59:59.000Z

    We analyze the present day structure and assembly history of a high-resolution hydrodynamic simulation of the formation of a Milky-Way-(MW)-like disk galaxy, from the ''Eris'' simulation suite, dissecting it into cohorts of stars formed at different epochs of cosmic history. At z = 0, stars with t{sub form} < 2 Gyr mainly occupy the stellar spheroid, with the oldest (earliest forming) stars having more centrally concentrated profiles. The younger age cohorts populate disks of progressively longer radial scale lengths and shorter vertical scale heights. At a given radius, the vertical density profiles and velocity dispersions of stars vary smoothly as a function of age, and the superposition of old, vertically extended and young, vertically compact cohorts gives rise to a double-exponential profile like that observed in the MW. Turning to formation history, we find that the trends of spatial structure and kinematics with stellar age are largely imprinted at birth, or immediately thereafter. Stars that form during the active merger phase at z > 3 are quickly scattered into rounded, kinematically hot configurations. The oldest disk cohorts form in structures that are radially compact and relatively thick, while subsequent cohorts form in progressively larger, thinner, colder configurations from gas with increasing levels of rotational support. The disk thus forms ''inside out'' in a radial sense and ''upside down'' in a vertical sense. Secular heating and radial migration influence the final state of each age cohort, but the changes they produce are small compared to the trends established at formation. The predicted correlations of stellar age with spatial and kinematic structure are in good qualitative agreement with the correlations observed for mono-abundance stellar populations in the MW.

  6. A CMOS-compatible compact display

    E-Print Network [OSTI]

    Chen, Andrew R. (Andrew Raymond)

    2005-01-01T23:59:59.000Z

    Portable information devices demand displays with high resolution and high image quality that are increasingly compact and energy-efficient. Microdisplays consisting of a silicon CMOS backplane integrated with light ...

  7. Steady state compact toroidal plasma production

    DOE Patents [OSTI]

    Turner, William C. (Livermore, CA)

    1986-01-01T23:59:59.000Z

    Apparatus and method for maintaining steady state compact toroidal plasmas. A compact toroidal plasma is formed by a magnetized coaxial plasma gun and held in close proximity to the gun electrodes by applied magnetic fields or magnetic fields produced by image currents in conducting walls. Voltage supply means maintains a constant potential across the electrodes producing an increasing magnetic helicity which drives the plasma away from a minimum energy state. The plasma globally relaxes to a new minimum energy state, conserving helicity according to Taylor's relaxation hypothesis, and injecting net helicity into the core of the compact toroidal plasma. Controlling the voltage so as to inject net helicity at a predetermined rate based on dissipative processes maintains or increases the compact toroidal plasma in a time averaged steady state mode.

  8. Gravitational waves from merging compact binaries

    E-Print Network [OSTI]

    Hughes, Scott A.

    Largely motivated by the development of highly sensitive gravitational-wave detectors, our understanding of merging compact binaries and the gravitational waves they generate has improved dramatically in recent years. ...

  9. Southern States Energy Compact (Multiple States)

    Broader source: Energy.gov [DOE]

    The Southern States Energy Compact provides for the proper employment and conservation of energy, and for the employment of energy-related facilities, materials, and products, within the context of...

  10. Belle Fourche River Compact (South Dakota)

    Broader source: Energy.gov [DOE]

    The Belle Fourche River Compact, agreed to by South Dakota and Wyoming, seeks to provide for the most efficient use of the waters of the Belle Fourche River Basin for multiple purposes, and to...

  11. Compact reflective imaging spectrometer utilizing immersed gratings

    DOE Patents [OSTI]

    Chrisp, Michael P. (Danville, CA)

    2006-05-09T23:59:59.000Z

    A compact imaging spectrometer comprising an entrance slit for directing light, a first mirror that receives said light and reflects said light, an immersive diffraction grating that diffracts said light, a second mirror that focuses said light, and a detector array that receives said focused light. The compact imaging spectrometer can be utilized for remote sensing imaging spectrometers where size and weight are of primary importance.

  12. Compact binary mergers: an astrophysical perspective

    E-Print Network [OSTI]

    S. Rosswog

    2010-12-22T23:59:59.000Z

    This paper reviews the current understanding of double neutron star and neutron star black hole binaries. It addresses mainly (nuclear) astrophysics aspects of compact binary mergers and thus complements recent reviews that have emphasized the numerical relativity viewpoint. In particular, the paper discusses different channels to release neutron-rich matter into the host galaxy, connections between compact binary mergers and short Gamma-ray bursts and accompanying electromagnetic signals.

  13. Technology Selections for Cylindrical Compact Fabrication

    SciTech Connect (OSTI)

    Jeffrey A. Phillips

    2010-10-01T23:59:59.000Z

    A variety of process approaches are available and have been used historically for manufacture of cylindrical fuel compacts. The jet milling, fluid bed overcoating, and hot press compacting approach being adopted in the U.S. AGR Fuel Development Program for scale-up of the compacting process involves significant paradigm shifts from historical approaches. New methods are being pursued because of distinct advantages in simplicity, yield, and elimination of process mixed waste. Recent advances in jet milling technology allow simplified dry matrix powder preparation. The matrix preparation method is well matched with patented fluid bed powder overcoating technology recently developed for the pharmaceutical industry and directly usable for high density fuel particle matrix overcoating. High density overcoating places fuel particles as close as possible to their final position in the compact and is matched with hot press compacting which fully fluidizes matrix resin to achieve die fill at low compacting pressures and without matrix end caps. Overall the revised methodology provides a simpler process that should provide very high yields, improve homogeneity, further reduce defect fractions, eliminate intermediate grading and QC steps, and allow further increases in fuel packing fractions.

  14. Soil Quality Information Sheet Rangeland Soil Quality--Compaction

    E-Print Network [OSTI]

    Soil Quality Information Sheet Rangeland Soil Quality--Compaction USDA, Natural Resources Conservation Service May 2001 Rangeland Sheet 4 What is compaction? Soil compaction occurs when moist or wet soil aggregates are pressed together and the pore space between them is reduced. Compaction changes

  15. Compact Proof Certificates For Linear Logic Kaustuv Chaudhuri

    E-Print Network [OSTI]

    Chaudhuri, Kaustuv

    Compact Proof Certificates For Linear Logic Kaustuv Chaudhuri INRIA, France http://kaustuv.chaudhuri

  16. SLAC-PUB-15193 Compact

    Office of Scientific and Technical Information (OSTI)

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItem Not Found Item Not Foundenhancer activityRenewable Energy Agricultural076 The93

  17. Electric Transmission Line Siting Compact

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

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742Energy Chinaof EnergyImpactOn July 2, 2014 in theGroup ReportLowand ContactDepartmentElectric

  18. Stellar Feedback in Dwarf Galaxy Formation

    E-Print Network [OSTI]

    Sergey Mashchenko; James Wadsley; H. M. P. Couchman

    2007-11-29T23:59:59.000Z

    Dwarf galaxies pose significant challenges for cosmological models. In particular, current models predict a dark matter density that is divergent at the center, in sharp contrast with observations which indicate an approximately constant central density core. Energy feedback, from supernova explosions and stellar winds, has been proposed as a major factor shaping the evolution of dwarf galaxies. We present detailed cosmological simulations with sufficient resolution both to model the relevant physical processes and to directly assess the impact of stellar feedback on observable properties of dwarf galaxies. We show that feedback drives large-scale, bulk motion of the interstellar gas resulting in significant gravitational potential fluctuations and a consequent reduction in the central matter density, bringing the theoretical predictions in agreement with observations.

  19. The Evolution of Stellar Exponential Discs

    E-Print Network [OSTI]

    Annette Ferguson; Cathie Clarke

    2001-03-14T23:59:59.000Z

    Models of disc galaxies which invoke viscosity-driven radial flows have long been known to provide a natural explanation for the origin of stellar exponential discs, under the assumption that the star formation and viscous timescales are comparable. We present models which invoke simultaneous star formation, viscous redistribution of gas and cosmologically-motivated gaseous infall and explore the predictions such models make for the scale length evolution and radial star formation history of galactic stellar discs. While the inclusion of viscous flows is essential for ensuring that the stellar disc is always exponential over a significant range in radius, we find that such flows play essentially no role in determining the evolution of the disc scale length. In models in which the main infall phase precedes the onset of star formation and viscous evolution, we find the exponential scale length to be rather invariant with time. On the other hand, models in which star formation/viscous evolution and infall occur concurrently result in a smoothly increasing scale length with time, reflecting the mean angular momentum of material which has fallen in at any given epoch. The disc stellar populations in these models are predominantly young (ie. ages < 5 Gyr) beyond a few scale lengths. In both cases, viscous flows are entirely responsible for transporting material to very large radii. We discuss existing observational constraints on these models from studies of both local and moderate redshift disc galaxies. In particular, a good agreement is found between the solar neighbourhood star formation history predicted by our infall model and the recent observational determination of this quantity by Rocha-Pinto et al (2000).

  20. Upgrade of the neutral particle analyzers for the TJ-II stellarator

    SciTech Connect (OSTI)

    Fontdecaba, J. M., E-mail: josepmaria.fontdecaba@ciemat.es; Ros, A.; McCarthy, K. J. [Laboratorio Nacional de Fusión, CIEMAT, Madrid 28040 (Spain); Petrov, S. Ya.; Nesenevich, V. G.; Chernyshev, F. V. [Ioffe Physical-Technical Institute, Saint Petersburg 194024 (Russian Federation); Barcala, J. M. [Departamento de Electrónica, CIEMAT, Madrid 28040 (Spain)

    2014-11-15T23:59:59.000Z

    The TJ-II stellarator, a magnetically confined plasma device, is equipped with a broad range of diagnostics for plasma characterization. These include 4 neutral particle analyzers (NPAs), consisting of two Acord-12's, to perform poloidal measurements, plus a compact NPA, and an Acord-24, these in tangential viewing positions. The Acord-12's were originally equipped with two rows of 6 channels each, one for hydrogen neutrals and the other for deuterium neutrals but were changed to a single row of 12 detectors for hydrogen, the principal working gas in TJ-II. With this upgrade the resultant improved energy resolution spectrum has allowed more reliable ion temperature estimates to be obtained. Here we present the upgrades undertaken and present results to demonstrate the improved performance of this diagnostic.

  1. Strategy Guideline: Compact Air Distribution Systems

    SciTech Connect (OSTI)

    Burdick, A.

    2013-06-01T23:59:59.000Z

    This Strategy Guideline discusses the benefits and challenges of using a compact air distribution system to handle the reduced loads and reduced air volume needed to condition the space within an energy efficient home. Traditional systems sized by 'rule of thumb' (i.e., 1 ton of cooling per 400 ft2 of floor space) that 'wash' the exterior walls with conditioned air from floor registers cannot provide appropriate air mixing and moisture removal in low-load homes. A compact air distribution system locates the HVAC equipment centrally with shorter ducts run to interior walls, and ceiling supply outlets throw the air toward the exterior walls along the ceiling plane; alternatively, high sidewall supply outlets throw the air toward the exterior walls. Potential drawbacks include resistance from installing contractors or code officials who are unfamiliar with compact air distribution systems, as well as a lack of availability of low-cost high sidewall or ceiling supply outlets to meet the low air volumes with good throw characteristics. The decision criteria for a compact air distribution system must be determined early in the whole-house design process, considering both supply and return air design. However, careful installation of a compact air distribution system can result in lower material costs from smaller equipment, shorter duct runs, and fewer outlets; increased installation efficiencies, including ease of fitting the system into conditioned space; lower loads on a better balanced HVAC system, and overall improved energy efficiency of the home.

  2. Coherent change detection and interferometric ISAR measurements in the folded compact range

    SciTech Connect (OSTI)

    Sorensen, K.W.

    1996-08-01T23:59:59.000Z

    A folded compact range configuration has been developed ant the Sandia National Laboratories` compact range antenna and radar-cross- section measurement facility as a means of performing indoor, environmentally-controlled, far-field simulations of synthetic aperture radar (SAR) measurements of distributed target samples (i.e. gravel, sand, etc.). The folded compact range configuration has previously been used to perform coherent-change-detection (CCD) measurements, which allow disturbances to distributed targets on the order of fractions of a wavelength to be detected. This report describes follow-on CCD measurements of other distributed target samples, and also investigates the sensitivity of the CCD measurement process to changes in the relative spatial location of the SAR sensor between observations of the target. Additionally, this report describes the theoretical and practical aspects of performing interferometric inverse-synthetic-aperture-radar (IFISAR) measurements in the folded compact range environment. IFISAR measurements provide resolution of the relative heights of targets with accuracies on the order of a wavelength. Several examples are given of digital height maps that have been generated from measurements performed at the folded compact range facility.

  3. A new method for deriving the stellar birth function of resolved stellar populations

    E-Print Network [OSTI]

    Gennaro, Mario; Brown, Tom; Gordon, Karl

    2015-01-01T23:59:59.000Z

    We present a new method for deriving the stellar birth function (SBF) of resolved stellar populations. The SBF (stars born per unit mass, time, and metallicity) is the combination of the initial mass function (IMF), the star-formation history (SFH), and the metallicity distribution function (MDF). The framework of our analysis is that of Poisson Point Processes (PPPs), a class of statistical models suitable when dealing with points (stars) in a multidimensional space (the measurement space of multiple photometric bands). The theory of PPPs easily accommodates the modeling of measurement errors as well as that of incompleteness. Compared to most of the tools used to study resolved stellar populations, our method avoids binning stars in the color-magnitude diagram and uses the entirety of the information (i.e., the whole likelihood function) for each data point; the proper combination of the individual likelihoods allows the computation of the posterior probability for the global population parameters. This inc...

  4. Cylindrically Symmetric Models of Anisotropic Compact Stars

    E-Print Network [OSTI]

    G. Abbas; Sumara Nazeer; M. A. Meraj

    2014-12-16T23:59:59.000Z

    In this paper we have discussed the possibility of forming anisotropic compact stars from cosmological constant as one of the competent candidates of dark energy with cylindrical symmetry. For this purpose, we have applied the analytical solution of Krori and Barua metric to a particular cylindrically symmetric spacetime. The unknown constants in Krori and Barua metric have been determined by using masses and radii of class of compact stars like 4$U$1820-30, Her X-1, SAX J 1808-3658. The properties of these stars have been analyzed in detail. In this setting the cosmological constant has been taken as a variable which depends on the radial coordinates. We have checked all the regularity conditions, stability and surface redshift of the compact stars 4$U$1820-30, Her X-1, SAX J 1808-3658.

  5. The Influence of Stellar Energetics and Dark Matter on the Chemical Evolution of Dwarf Irregulars

    E-Print Network [OSTI]

    F. Bradamante; F. Matteucci; A. D'Ercole

    1998-01-14T23:59:59.000Z

    A chemical evolution model following the evolution of the abundances of H, He, C, N, O and Fe for dwarf irregular and blue compact galaxies is presented. This model takes into account detailed nucleosynthesis and computes in detail the rates of supernovae of type II and I. The star formation is assumed to have proceeded in short but intense bursts. The novelty relative to previous models is that the development of a galactic wind is studied in detail by taking into account the energy injected into the interstellar medium (ISM) from both supernovae and stellar winds from massive stars as well as the presence of dark matter halos. Both metal enriched and normal winds have been considered. Our main conclusions are: i) a substantial amount of dark matter (from 1 to 50 times larger than the luminous matter) is required in order to avoid the complete destruction of such galaxies during strong starbursts, and ii) the energy injected by stellar winds and type Ia supernovae into the ISM is negligible relative to the total thermal energy, and in particular to the type II supernovae, which in fact, dominate the energetics during starbursts.

  6. Remote vacuum compaction of compressible hazardous waste

    DOE Patents [OSTI]

    Coyne, M.J.; Fiscus, G.M.; Sammel, A.G.

    1998-10-06T23:59:59.000Z

    A system is described for remote vacuum compaction and containment of low-level radioactive or hazardous waste comprising a vacuum source, a sealable first flexible container, and a sealable outer flexible container for receiving one or more first flexible containers. A method for compacting low level radioactive or hazardous waste materials at the point of generation comprising the steps of sealing the waste in a first flexible container, sealing one or more first containers within an outer flexible container, breaching the integrity of the first containers, evacuating the air from the inner and outer containers, and sealing the outer container shut. 8 figs.

  7. Remote vacuum compaction of compressible hazardous waste

    DOE Patents [OSTI]

    Coyne, Martin J. (Pittsburgh, PA); Fiscus, Gregory M. (McMurray, PA); Sammel, Alfred G. (Pittsburgh, PA)

    1998-01-01T23:59:59.000Z

    A system for remote vacuum compaction and containment of low-level radioactive or hazardous waste comprising a vacuum source, a sealable first flexible container, and a sealable outer flexible container for receiving one or more first flexible containers. A method for compacting low level radioactive or hazardous waste materials at the point of generation comprising the steps of sealing the waste in a first flexible container, sealing one or more first containers within an outer flexible container, breaching the integrity of the first containers, evacuating the air from the inner and outer containers, and sealing the outer container shut.

  8. Stellar Activity and Coronal Heating: an overview of recent results

    E-Print Network [OSTI]

    Testa, Paola; Drake, Jeremy

    2015-01-01T23:59:59.000Z

    Observations of the coronae of the Sun and of solar-like stars provide complementary information to advance our understanding of stellar magnetic activity, and of the processes leading to the heating of their outer atmospheres. While solar observations allow us to study the corona at high spatial and temporal resolution, the study of stellar coronae allows us to probe stellar activity over a wide range of ages and stellar parameters. Stellar studies therefore provide us with additional tools for understanding coronal heating processes, as well as the long-term evolution of solar X-ray activity. We discuss how recent studies of stellar magnetic fields and coronae contribute to our understanding of the phenomenon of activity and coronal heating in late-type stars.

  9. DETERMINATION OF STELLAR RADII FROM ASTEROSEISMIC DATA

    SciTech Connect (OSTI)

    Basu, Sarbani [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Chaplin, William J.; Elsworth, Yvonne, E-mail: sarbani.basu@yale.ed, E-mail: w.j.chaplin@bham.ac.u, E-mail: y.p.elsworth@bham.ac.u [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2010-02-20T23:59:59.000Z

    The NASA Kepler mission is designed to find planets through transits. Accurate and precise radii of the detected planets depend on knowing the radius of the host star accurately, which is difficult unless the temperature and luminosity of the star are known precisely. Kepler, however, has an asteroseismology program that will provide seismic variables that can characterize stellar radii easily, accurately, and extremely precisely. In this paper, we describe the Yale-Birmingham (YB) method to determine stellar radii using a combination of seismic and conventional variables and analyze the effect of these variables on the result. We find that for main-sequence stars, a knowledge of the parallax is not important to get accurate radii using the YB method: we can get results to an accuracy and precision of better than a few percent if we know the effective temperature and the seismic parameters for these stars. Metallicity does not make much difference either. However, good estimates of the effective temperature and metallicity, along with those of the seismic parameters, are essential to determine radii of subgiants properly. On the other hand, for red giants we find that determining radii properly is not possible without a good estimate of the parallax. We find that the so-called 'surface term' in the seismic data has minimal effect on the inferred radii. Uncertainties in the convective mixing length can matter under some circumstances and can cause a systematic shift in the inferred radii. Blind tests with data simulated to match those expected from the asteroseismic survey phase of Kepler show that it will be possible to infer stellar radii successfully using our method.

  10. On chaotic behavior of gravitating stellar shells

    E-Print Network [OSTI]

    M. V. Barkov; G. S. Bisnovatyi-Kogan; A. I. Neishtadt; V. A. Belinski

    2004-12-10T23:59:59.000Z

    Motion of two gravitating spherical stellar shells around a massive central body is considered. Each shell consists of point particles with the same specific angular momenta and energies. In the case when one can neglect the influence of gravitation of one ("light") shell onto another ("heavy") shell ("restricted problem") the structure of the phase space is described. The scaling laws for the measure of the domain of chaotic motion and for the minimal energy of the light shell sufficient for its escape to infinity are obtained.

  11. Stellar Energy Solutions Inc | Open Energy Information

    Open Energy Info (EERE)

    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: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov YouKizildere IRaghuraji Agro Industries Pvt LtdShawangunk,SoutheastSt.Steep Gradient Flume Jump to: navigation,Stellar

  12. Distinguishing compact binary population synthesis models using gravitational-wave observations of coalescing binary black holes

    E-Print Network [OSTI]

    Stevenson, Simon; Fairhurst, Stephen

    2015-01-01T23:59:59.000Z

    The coalescence of compact binaries containing neutron stars or black holes is one of the most promising signals for advanced ground-based laser interferometer gravitational-wave detectors, with the first direct detections expected over the next few years. The rate of binary coalescences and the distribution of component masses is highly uncertain, and population synthesis models predict a wide range of plausible values. Poorly constrained parameters in population synthesis models correspond to poorly understood astrophysics at various stages in the evolution of massive binary stars, the progenitors of binary neutron star and binary black hole systems. These include effects such as supernova kick velocities, parameters governing the energetics of common envelope evolution and the strength of stellar winds. Observing multiple binary black hole systems through gravitational waves will allow us to infer details of the astrophysical mechanisms that lead to their formation. We simulate gravitational-wave observati...

  13. Scientists use plasma shaping to control turbulence in stellarators...

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

    Scientists use plasma shaping to control turbulence in stellarators By John Greenwald By John Greenwald October 21, 2014 Tweet Widget Google Plus One Share on Facebook Magnetic...

  14. Frontiers in Planetary and Stellar Magnetism through High-Performance...

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

    Hwang, project co-PI Frontiers in Planetary and Stellar Magnetism through High-Performance Computing PI Name: Jonathan Aurnou PI Email: aurnou@ucla.edu Institution: University...

  15. Preferential Path Profiling: Compactly Numbering Interesting Paths

    E-Print Network [OSTI]

    Chilimbi, Trishul

    preferential path profiling (PPP), that reduces the overhead of path profiling. PPP leverages the observation that most consumers of path profiles are only inter- ested in a subset of all program paths. PPP achieves produced by PPP. This compact path numbering enables our PPP implementation to record path information

  16. Compact range for variable-zone measurements

    DOE Patents [OSTI]

    Burnside, Walter D. (Columbus, OH); Rudduck, Roger C. (Columbus, OH); Yu, Jiunn S. (Albuquerque, NM)

    1988-01-01T23:59:59.000Z

    A compact range for testing antennas or radar targets includes a source for directing energy along a feedline toward a parabolic reflector. The reflected wave is a spherical wave with a radius dependent on the distance of the source from the focal point of the reflector.

  17. Compact Ultradense Objects in the Solar System

    E-Print Network [OSTI]

    J. Rafelski; Ch. Dietl; L. Labun

    2013-03-19T23:59:59.000Z

    We describe properties and gravitational interactions of meteor-mass and greater compact ultra dense objects with nuclear density or greater (CUDO s). We discuss possible enclosure of CUDO s in comets, stability of these objects on impact with the Earth and Sun and show that the hypothesis of a CUDO core helps resolve issues challenging the understanding of a few selected cometary impacts.

  18. A Global Compact to End Poverty

    E-Print Network [OSTI]

    A Global Compact to End Poverty Jeffrey Sachs on stabilisation, transition and weapons of mass progress. We can realistically envision a world without extreme poverty by the year 2025 because. Sachs, The End of Poverty, 2005. WORLD ECONOMICS · Vol. 6 · No. 4 · October­December 2005 11 Jeffrey D

  19. Pathway to a Compact SASE FEL Device

    E-Print Network [OSTI]

    Dattoli, G; Petrillo, V; Rau, J V; Sabia, E; Spassovsky, I; Biedron, S G; Einstein, J; Milton, S V

    2015-01-01T23:59:59.000Z

    Newly developed high peak power lasers have opened the possibilities of driving coherent light sources operating with laser plasma accelerated beams and wave undulators. We speculate on the combination of these two concepts and show that the merging of the underlying technologies could lead to new and interesting possibilities to achieve truly compact, coherent radiator devices.

  20. THE LOCATIONS OF SHORT GAMMA-RAY BURSTS AS EVIDENCE FOR COMPACT OBJECT BINARY PROGENITORS

    SciTech Connect (OSTI)

    Fong, W.; Berger, E. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-10-10T23:59:59.000Z

    We present a detailed investigation of Hubble Space Telescope rest-frame UV/optical observations of 22 short gamma-ray burst (GRB) host galaxies and sub-galactic environments. Utilizing the high angular resolution and depth of HST we characterize the host galaxy morphologies, measure precise projected physical and host-normalized offsets between the bursts and host centers, and calculate the locations of the bursts with respect to their host light distributions (rest-frame UV and optical). We calculate a median short GRB projected physical offset of 4.5 kpc, about 3.5 times larger than that for long GRBs, and find that ?25% of short GRBs have offsets of ?> 10 kpc. When compared to their host sizes, the median offset is 1.5 half-light radii (r{sub e} ), about 1.5 times larger than the values for long GRBs, core-collapse supernovae, and Type Ia supernovae. In addition, ?20% of short GRBs having offsets of ?> 5r{sub e} , and only ?25% are located within 1r{sub e} . We further find that short GRBs severely under-represent their hosts' rest-frame optical and UV light, with ?30%-45% of the bursts located in regions of their host galaxies that have no detectable stellar light, and ?55% in the regions with no UV light. Therefore, short GRBs do not occur in regions of star formation or even stellar mass. This demonstrates that the progenitor systems of short GRBs must migrate from their birth sites to their eventual explosion sites, a signature of kicks in compact object binary systems. Utilizing the full sample of offsets, we estimate natal kick velocities of ?20-140 km s{sup –1}. These independent lines of evidence provide the strongest support to date that short GRBs result from the merger of compact object binaries (NS-NS/NS-BH)

  1. Plasma-enhanced gasification of low-grade coals for compact power plants

    SciTech Connect (OSTI)

    Uhm, Han S. [Department of Electrophysics, Kwangwoon University, 447-1 Wolgye-Dong, Nowon-Gu, Seoul 139-701 (Korea, Republic of); Hong, Yong C.; Shin, Dong H.; Lee, Bong J. [Convergence Plasma Research Center, National Fusion Research Institute, 113 Gwahangno, Yuseong-Gu, Daejeon 305-333 (Korea, Republic of)

    2011-10-15T23:59:59.000Z

    A high temperature of a steam torch ensures an efficient gasification of low-grade coals, which is comparable to that of high-grade coals. Therefore, the coal gasification system energized by microwaves can serve as a moderately sized power plant due to its compact and lightweight design. This plasma power plant of low-grade coals would be useful in rural or sparsely populated areas without access to a national power grid.

  2. Southeast Interstate Low-Level Radioactive Waste Management Compact (multi-state)

    Broader source: Energy.gov [DOE]

    The Southeast Interstate Low-Level Radioactive Waste Management Compact is administered by the Compact Commission. The Compact provides for rotating responsibility for the region's low-level...

  3. Stellar evolution and the triple-? reactions

    SciTech Connect (OSTI)

    Suda, Takuma [Osawa 2-21-1, Mitaka, Tokyo, 181-8588 (Japan)

    2014-05-02T23:59:59.000Z

    Nuclear reaction rates play a crucial role in the evolution of stars. For low-mass stars, the triple-? reaction controls the helium burning stars in the red giant and asymptotic giant branch (AGB) phase. More importantly, the cross section of the triple-? reaction has a great impact on the helium ignition at the center of the electron degenerate helium core of red giants and on the helium shell flashes of AGB stars. It is to be noted that stellar evolution models are influenced not only by the value of the cross section, but also by the temperature dependence of the reaction rate. In this paper, I present the impact of the triple-? reaction rates on the evolution of low-mass metal-free stars and intermediate-mass AGB stars. According to the previous study, the constraint on the triple-? reaction rate is derived based on stellar evolution theory. It is found that the recent revisions of the rate proposed by nuclear physics calculations satisfy the condition for the ignition of the helium core flash in low-mass stars.

  4. Geoscience laser altimeter system - stellar reference system

    SciTech Connect (OSTI)

    Millar, Pamela S.; Sirota, J. Marcos [NASA Goddard Space Flight Center, Laser Remote Sensing Branch, Code 924, Greenbelt, Maryland, 20771 (United States); University of Maryland at Baltimore County, 5401 Wilkens Ave, Baltimore, Maryland, 21228-5398 (United States)

    1998-01-15T23:59:59.000Z

    GLAS is an EOS space-based laser altimeter being developed to profile the height of the Earth's ice sheets with {approx}15 cm single shot accuracy from space under NASA's Mission to Planet Earth (MTPE). The primary science goal of GLAS is to determine if the ice sheets are increasing or diminishing for climate change modeling. This is achieved by measuring the ice sheet heights over Greenland and Antarctica to 1.5 cm/yr over 100 kmx100 km areas by crossover analysis (Zwally 1994). This measurement performance requires the instrument to determine the pointing of the laser beam to {approx}5 urad (1 arcsecond), 1-sigma, with respect to the inertial reference frame. The GLAS design incorporates a stellar reference system (SRS) to relate the laser beam pointing angle to the star field with this accuracy. This is the first time a spaceborne laser altimeter is measuring pointing to such high accuracy. The design for the stellar reference system combines an attitude determination system (ADS) with a laser reference system (LRS) to meet this requirement. The SRS approach and expected performance are described in this paper.

  5. EA-1437: Finding of No Significant Impact | Department of Energy

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

    fissionable uranium used in present-day nuclear reactors, and the limitations of solar, hydro and wind alternatives. Proposed National Compact Stellarator Equipment Princeton...

  6. Production, Cost, and Soil Compaction Estimates for Two Western Juniper

    E-Print Network [OSTI]

    Dodson, Beth

    , Crook County Soil and Water Conservation District, Prineville, OR 97754. ABSTRACT: Harvesting trialsProduction, Cost, and Soil Compaction Estimates for Two Western Juniper Extraction Systems, production rates, and soil compaction impacts of two systems for harvesting western juniper (Juniperus

  7. Fundamental building blocks for a compact optoelectronic neural network processor

    E-Print Network [OSTI]

    Ruedlinger, Benjamin Franklin, 1976-

    2003-01-01T23:59:59.000Z

    The focus of this thesis is interconnects within the Compact Optoelectronic Neural Network Processor. The goal of the Compact Optoelectronic Neural Network Processor Project (CONNPP) is to build a small, rugged neural ...

  8. A thermodynamic approach for compaction of asphaltic composites

    E-Print Network [OSTI]

    Koneru, Saradhi

    2009-05-15T23:59:59.000Z

    and Focus of Current Work . . . . . . . . . . . . . . 2 B. Outline of the Thesis . . . . . . . . . . . . . . . . . . . . . 3 C. Notations Used . . . . . . . . . . . . . . . . . . . . . . . . 4 II LITERATURE REVIEW... . . . . . . . . . . . . . . . . 8 b. Asphalt Binder . . . . . . . . . . . . . . . . . . . 8 C. Compaction Equipment . . . . . . . . . . . . . . . . . . . . 9 1. Field Compaction Equipment . . . . . . . . . . . . . . 9 a. Static Steel Wheel Rollers . . . . . . . . . . . . . 9 b...

  9. A template bank to search for gravitational waves from inspiralling compact binaries: II. Phenomenological model

    E-Print Network [OSTI]

    Thomas Cokelaer

    2007-09-07T23:59:59.000Z

    Matched filtering is used to search for gravitational waves emitted by inspiralling compact binaries in data from ground-based interferometers. One of the key aspects of the detection process is the deployment of a set of templates, also called a template bank, to cover the astrophysically interesting region of the parameter space. In a companion paper, we described the template-bank algorithm used in the analysis of LIGO data to search for signals from non-spinning binaries made of neutron star and/or stellar-mass black holes; this template bank is based upon physical template families. In this paper, we describe the phenomenological template bank that was used to search for gravitational waves from non-spinning black hole binaries (from stellar mass formation) in the second, third and fourth LIGO science runs. We briefly explain the design of the bank, whose templates are based on a phenomenological detection template family. We show that this template bank gives matches greater than 95% with the physical template families that are expected to be captured by the phenomenological templates.

  10. A study of compaction methods for lunar soil simulants

    E-Print Network [OSTI]

    Ekkad, Rama Varadarajan

    1993-01-01T23:59:59.000Z

    , compaction by vibration, compaction under vacuum pressure under the simultaneous effect of vibration are examined. Duc to the increasing confining pressure, the air voids decrease and the particles will be more closely packed, thus increasing the relative... density. The research will be used to identify a convenient method for compacting samples for laboratory digging experiments. The results of the research conclude that compaction by using vacuum and vibration produce results which can be used to predict...

  11. Compact Radio Sources within 30" of Sgr A*: Proper Motions, Stellar Winds and the Accretion Rate onto Sgr A*

    E-Print Network [OSTI]

    Yusef-Zadeh, F; Schödel, R; Wardle, M; Cotton, W; Roberts, D A; Nogueras-Lara, F; Gallego-Cano, E

    2015-01-01T23:59:59.000Z

    Recent broad-band 34 and 44 GHz radio continuum observations of the Galactic center have revealed 41 massive stars identified with near-IR counterparts, as well as 44 proplyd candidates within 30" of Sgr A*. Radio observations obtained in 2011 and 2014 have been used to derive proper motions of eight young stars near Sgr A*. The accuracy of proper motion estimates based on near-IR observations by Lu et al. and Paumard et al. have been investigated by using their proper motions to predict the 2014 epoch positions of near-IR stars and comparing the predicted positions with those of radio counterparts in the 2014 radio observations. Predicted positions from Lu et al. show an rms scatter of 6 mas relative to the radio positions, while those from Paumard et al. show rms residuals of 20 mas, which is mainly due to uncertainties in the IR-based proper motions. Under the assumption of homogeneous ionized winds, we also determine the mass-loss rates of 11 radio stars, finding rates that are on average $\\sim$2 times sm...

  12. Stellar Burning Falk Herwig, Alexander Heger, and Frank

    E-Print Network [OSTI]

    Herwig, Falk

    ]. In these objects, a thermonuclear runaway of the helium shell on top of an electron-degenerate core (a young White implications for the production of neutron- rich elements. log Tlog Teffeff Figure 1-- A thermonuclear runaway stellar conditions. We will include a stellar equation of state as well as thermonuclear burning (TN burn

  13. Gas Feedback on Stellar Bar Evolution

    E-Print Network [OSTI]

    Ingo Berentzen; Isaac Shlosman; Inma Martinez-Valpuesta; Clayton Heller

    2007-05-27T23:59:59.000Z

    We analyze evolution of live disk-halo systems in the presence of various gas fractions, f_gas less than 8% in the disk. We addressed the issue of angular momentum (J) transfer from the gas to the bar and its effect on the bar evolution. We find that the weakening of the bar, reported in the literature, is not related to the J-exchange with the gas, but is caused by the vertical buckling instability in the gas-poor disks and by a steep heating of a stellar velocity dispersion by the central mass concentration (CMC) in the gas-rich disks. The gas has a profound effect on the onset of the buckling -- larger f_gas brings it forth due to the more massive CMCs. The former process leads to the well-known formation of the peanut-shaped bulges, while the latter results in the formation of progressively more elliptical bulges, for larger f_gas. The subsequent (secular) evolution of the bar differs -- the gas-poor models exhibit a growing bar while gas-rich models show a declining bar whose vertical swelling is driven by a secular resonance heating. The border line between the gas-poor and -rich models lies at f_gas ~ 3% in our models, but is model-dependent and will be affected by additional processes, like star formation and feedback from stellar evolution. The overall effect of the gas on the evolution of the bar is not in a direct J transfer to the stars, but in the loss of J by the gas and its influx to the center that increases the CMC. The more massive CMC damps the vertical buckling instability and depopulates orbits responsible for the appearance of peanut-shaped bulges. The action of resonant and non-resonant processes in gas-poor and gas-rich disks leads to a converging evolution in the vertical extent of the bar and its stellar dispersion velocities, and to a diverging evolution in the bulge properties.

  14. Seoul National UniversitySeoul National University http://bp.snu.ac.kr1 The Effect of TiCl4-Treated TiO2

    E-Print Network [OSTI]

    Park, Byungwoo

    TiO2 Compact Layer on the Performance of Dye-Sensitized Solar Cell #12;Seoul National UniversitySeoul National University http://bp.snu.ac.kr Dye-Sensitized Solar Cell 2 Schematic Diagram of the Electron Flow by the TiO2 compact layer. Electrolyte Hydrolysis of TiCl4 Solution Dye-Coated TiO2 Back Electron Transfere

  15. Thermonuclear inverse magnetic pumping power cycle for stellarator reactor

    DOE Patents [OSTI]

    Ho, Darwin D. (Pleasanton, CA); Kulsrud, Russell M. (Princeton, NJ)

    1991-01-01T23:59:59.000Z

    The plasma column in a stellarator is compressed and expanded alternatively in minor radius. First a plasma in thermal balance is compressed adiabatically. The volume of the compressed plasma is maintained until the plasma reaches a new thermal equilibrium. The plasma is then expanded to its original volume. As a result of the way a stellarator works, the plasma pressure during compression is less than the corresponding pressure during expansion. Therefore, negative work is done on the plasma over a complete cycle. This work manifests itself as a back-voltage in the toroidal field coils. Direct electrical energy is obtained from this voltage. Alternatively, after the compression step, the plasma can be expanded at constant pressure. The cycle can be made self-sustaining by operating a system of two stellarator reactors in tandem. Part of the energy derived from the expansion phase of a first stellarator reactor is used to compress the plasma in a second stellarator reactor.

  16. Asteroseismic Diagnostics of Stellar Convective Cores

    E-Print Network [OSTI]

    Anwesh Mazumdar; Sarbani Basu; Braxton L. Collier; Pierre Demarque

    2006-08-16T23:59:59.000Z

    We present a detailed study of the small frequency separations as diagnostics of the mass of the convective core and evolutionary stage of solar-type stars. We demonstrate how the small separations can be combined to provide sensitive tests for the presence of convective overshoot at the edge of the core. These studies are focused on low degree oscillation modes, the only modes expected to be detected in distant stars. Using simulated data with realistic errors, we find that the mass of the convective core can be estimated to within 5% if the total stellar mass is known. Systematic errors arising due to uncertainty in the mass could be up to 20%. The evolutionary stage of the star, determined in terms of the central hydrogen abundance using our proposed technique, however, is much less sensitive to the mass estimate.

  17. Understanding the Stellar Initial Mass Function

    E-Print Network [OSTI]

    Richard B. Larson

    2006-03-21T23:59:59.000Z

    The essential features of the stellar Initial Mass Function are, rather generally, (1) a peak at a mass of a few tenths of a solar mass, and (2) a power-law tail toward higher masses that is similar to the original Salpeter function. Recent work suggests that the IMF peak reflects a preferred scale of fragmentation associated with the transition from a cooling phase of collapse at low densities to a nearly isothermal phase at higher densities, where the gas becomes thermally coupled to the dust. The Salpeter power law is plausibly produced, at least in part, by scale-free accretion processes that build up massive stars in dense environments. The young stars at the Galactic Center appear to have unusually high masses, possibly because of a high minimum mass resulting from the high opacity of the dense star-forming gas.

  18. Stellar mixing length theory with entropy rain

    E-Print Network [OSTI]

    Brandenburg, Axel

    2015-01-01T23:59:59.000Z

    Stellar mixing length theory is modified to include the effects of a nongradient term that originates from the motion of convective elements with entropy perturbations of either sign. It is argued that such a term, first studied by Deardorff in the meteorological context, represents the effects of thin intense downdrafts caused by the rapid cooling in the granulation layer at the top of the convection zone. They transport heat nonlocally, as originally anticipated by Spruit in the 1990s, who describes the convection in the strongly stratified simulations of Stein & Nordlund as entropy rain. Although our model has ill-determined free parameters, it demonstrates that solutions can be found that look similar to the original ones, except that the deeper layers are now Schwarzschild stable, so no giant cells are produced and the typical convective scale is that of granules even at larger depth. Consequences for modeling solar differential, the global dynamo, and sunspots are briefly discussed.

  19. Electromagnetic Pulse from Final Gravitational Stellar Collapse

    E-Print Network [OSTI]

    P. D. Morley; Ivan Schmidt

    2002-01-30T23:59:59.000Z

    We employ an effective gravitational stellar final collapse model which contains the relevant physics involved in this complex phenomena: spherical radical infall in the Schwarzschild metric of the homogeneous core of an advanced star, giant magnetic dipole moment, magnetohydrodynamic material response and realistic equations of state (EOS). The electromagnetic pulse is computed both for medium size cores undergoing hydrodynamic bounce and large size cores undergoing black hole formation. We clearly show that there must exist two classes of neutron stars, separated by maximum allowable masses: those that collapsed as solitary stars (dynamical mass limit) and those that collapsed in binary systems allowing mass accretion (static neutron star mass). Our results show that the electromagnetic pulse spectrum associated with black hole formation is a universal signature, independent of the nuclear EOS. Our results also predict that there must exist black holes whose masses are less than the static neutron star stability limit.

  20. A laboratory investigation of vibratory compaction of dry soils

    E-Print Network [OSTI]

    Webster, Cecil Ray

    1984-01-01T23:59:59.000Z

    . Standard Compaction Curve for Soil 3 (CL) 48 49 50 53 54 56 25 Effect of Frequency Variation on the Time Required to Achieve I/2 inch (12. 7 mm) of Settlement 57 26. Foot Size Effects on Compaction of Various Soils 59 27. Effect of Frequency... on the Compaction of Soil 1 (SP) Using Two Different Feet 63 28. Effect of Frequency on the Compaction of Soil 1 (SP) Using the Semi-Circular Foot with Various Static Weights 64 29. Effect of Frequency on the Compaction of Soil 1 (SP) Using the 5 Inch Diameter...

  1. Compact x-ray source and panel

    DOE Patents [OSTI]

    Sampayon, Stephen E. (Manteca, CA)

    2008-02-12T23:59:59.000Z

    A compact, self-contained x-ray source, and a compact x-ray source panel having a plurality of such x-ray sources arranged in a preferably broad-area pixelized array. Each x-ray source includes an electron source for producing an electron beam, an x-ray conversion target, and a multilayer insulator separating the electron source and the x-ray conversion target from each other. The multi-layer insulator preferably has a cylindrical configuration with a plurality of alternating insulator and conductor layers surrounding an acceleration channel leading from the electron source to the x-ray conversion target. A power source is connected to each x-ray source of the array to produce an accelerating gradient between the electron source and x-ray conversion target in any one or more of the x-ray sources independent of other x-ray sources in the array, so as to accelerate an electron beam towards the x-ray conversion target. The multilayer insulator enables relatively short separation distances between the electron source and the x-ray conversion target so that a thin panel is possible for compactness. This is due to the ability of the plurality of alternating insulator and conductor layers of the multilayer insulators to resist surface flashover when sufficiently high acceleration energies necessary for x-ray generation are supplied by the power source to the x-ray sources.

  2. The Evolution of Compact Binary Star Systems

    E-Print Network [OSTI]

    Konstantin Postnov; Lev Yungelson

    2014-03-21T23:59:59.000Z

    We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Mergings of compact binary stars are expected to be the most important sources for the forthcoming gravitational-wave (GW) astronomy. In the first part of the review, we discuss observational manifestations of close binary stars with NS and/or black components and their merger rate, crucial points in the formation and evolution of compact stars in binary systems, including the treatment of the natal kicks which NSs and BHs acquire during the core collapse of massive stars and the common envelope phase of binary evolution, which are most relevant to the merging rates of NS-NS, NS-BH and BH-BH binaries. The second part of the review is devoted mainly to formation and evolution of binary WDs and their observational manifestations, including their role as progenitors of cosmologically important thermonuclear SN Ia. We also consider AM CVn-stars which are thought to be the best verification binary GW sources for future low-frequency GW space interferometers.

  3. THE MERGER HISTORY, ACTIVE GALACTIC NUCLEUS, AND DWARF GALAXIES OF HICKSON COMPACT GROUP 59

    SciTech Connect (OSTI)

    Konstantopoulos, I. S.; Charlton, J. C.; Brandt, W. N.; Eracleous, M.; Gronwall, C. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Gallagher, S. C.; Fedotov, K.; Hill, A. R. [Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7 (Canada); Durrell, P. R. [Department of Physics and Astronomy, Youngstown State University, Youngstown, OH 44555 (United States); Tzanavaris, P.; Hornschemeier, A. E. [Laboratory for X-ray Astrophysics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Zabludoff, A. I. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Maier, M. L. [Gemini Observatory, Casilla 603, Colina el Pino S/N, La Serena (Chile); Elmegreen, D. M. [Department of Physics and Astronomy, Vassar College, Poughkeepsie, NY 12604 (United States); Johnson, K. E.; Walker, L. M. [Department of Astronomy, University of Virginia, P. O. Box 400325, Charlottesville, VA 22904 (United States); Maybhate, A. [Space Telescope Science Institute, Baltimore, MD (United States); English, J. [University of Manitoba, Winnipeg, MN (Canada); Mulchaey, J. S., E-mail: iraklis@astro.psu.edu [Carnegie Observatories, Pasadena, CA 91101 (United States)

    2012-01-20T23:59:59.000Z

    Compact group galaxies often appear unaffected by their unusually dense environment. Closer examination can, however, reveal the subtle, cumulative effects of multiple galaxy interactions. Hickson Compact Group (HCG) 59 is an excellent example of this situation. We present a photometric study of this group in the optical (Hubble Space Telescope), infrared (Spitzer), and X-ray (Chandra) regimes aimed at characterizing the star formation and nuclear activity in its constituent galaxies and intra-group medium. We associate five dwarf galaxies with the group and update the velocity dispersion, leading to an increase in the dynamical mass of the group of up to a factor of 10 (to 2.8 Multiplication-Sign 10{sup 13} M{sub Sun }), and a subsequent revision of its evolutionary stage. Star formation is proceeding at a level consistent with the morphological types of the four main galaxies, of which two are star-forming and the other are two quiescent. Unlike in some other compact groups, star-forming complexes across HCG 59 closely follow mass-radius scaling relations typical of nearby galaxies. In contrast, the ancient globular cluster populations in galaxies HCG 59A and B show intriguing irregularities, and two extragalactic H II regions are found just west of B. We age-date a faint stellar stream in the intra-group medium at {approx}1 Gyr to examine recent interactions. We detect a likely low-luminosity active galactic nucleus in HCG 59A by its {approx}10{sup 40} erg s{sup -1} X-ray emission; the active nucleus rather than star formation can account for the UV+IR spectral energy distribution. We discuss the implications of our findings in the context of galaxy evolution in dense environments.

  4. RADIO AND MID-INFRARED PROPERTIES OF COMPACT STARBURSTS: DISTANCING THEMSELVES FROM THE MAIN SEQUENCE

    SciTech Connect (OSTI)

    Murphy, E. J. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Stierwalt, S.; Armus, L. [Spitzer Science Center, California Institute of Technology, MC 314-6, Pasadena, CA 91125 (United States); Condon, J. J. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Evans, A. S., E-mail: emurphy@obs.carnegiescience.edu [Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904 (United States)

    2013-05-01T23:59:59.000Z

    We investigate the relationship between 8.44 GHz brightness temperatures and 1.4 to 8.44 GHz radio spectral indices with 6.2 {mu}m polycyclic aromatic hydrocarbon (PAH) emission and 9.7 {mu}m silicate absorption features for a sample of 36 local luminous and ultraluminous infrared galaxies. We find that galaxies having small 6.2 {mu}m PAH equivalent widths (EQWs), which signal the presence of weak PAH emission and/or an excess of very hot dust, also have flat spectral indices. The three active galactic nuclei (AGN) identified through their excessively large 8.44 GHz brightness temperatures are also identified as AGN via their small 6.2 {mu}m PAH EQWs. We also find that the flattening of the radio spectrum increases with increasing silicate optical depth, 8.44 GHz brightness temperature, and decreasing size of the radio source even after removing potential AGN, supporting the idea that compact starbursts show spectral flattening as the result of increased free-free absorption. These correlations additionally suggest that the dust obscuration in these galaxies must largely be coming from the vicinity of the compact starburst itself, and is not distributed throughout the (foreground) disk of the galaxy. Finally, we investigate the location of these infrared-bright systems relative to the main sequence (star formation rate versus stellar mass) of star-forming galaxies in the local universe. We find that the radio spectral indices of galaxies flatten with increasing distance above the main sequence, or in other words, with increasing specific star formation rate. This indicates that galaxies located above the main sequence, having high specific star formation rates, are typically compact starbursts hosting deeply embedded star formation that becomes more optically thick in the radio and infrared with increased distance above the main sequence.

  5. Interplay between Stellar Spirals and the ISM in Galactic Disks

    E-Print Network [OSTI]

    Wada, Keiichi; Saitoh, Takayuki R

    2011-01-01T23:59:59.000Z

    We propose a new dynamical picture of galactic stellar and gas spirals, based on hydrodynamic simulations in a `live' stellar disk. We focus especially on spiral structures excited in a isolated galactic disk without a stellar bar. Using high-resolution, 3-dimensional N-body/SPH simulations, we found that the spiral features of the gas in galactic disks are formed by essentially different mechanisms from the galactic shock in stellar density waves. The stellar spiral arms and the interstellar matter on average corotate in a galactic potential at any radii. Unlike the stream motions in the galactic shock, the interstellar matter flows into the local potential minima with irregular motions. The flows converge to form dense gas clouds/filaments near the bottom of the stellar spirals, whose global structures resemble dust-lanes seen in late-type spiral galaxies. The stellar arms are non-steady; they are wound and stretched by the galactic shear, and thus local densities of the arm change on a time scale of ~ 100 ...

  6. The Dark Energy Survey: Prospects for Resolved Stellar Populations

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

    Rossetto, Bruno M; Santiago, Basilio X; Girardi, Leo; Camargo, Julio I.B.; Balbinot, Eduardo; da Costa, Luiz N; Yanny, Brian; Maia, Marcio A.G.; Makler, Martin; Ogando, Ricardo L.C.; et al

    2011-05-06T23:59:59.000Z

    Wide angle and deep surveys, regardless of their primary purpose, always sample a large number of stars in the Galaxy and in its satellite system. We here make a forecast of the expected stellar sample resulting from the Dark Energy Survey and the perspectives that it will open for studies of Galactic structure and resolved stellar populations in general. An estimated 1.2 x 10{sup 8} stars will be sampled in DES grizY filters in the southern equatorial hemisphere. This roughly corresponds to 20% of all DES sources. Most of these stars belong to the stellar thick disk and halo ofmore »the Galaxy.« less

  7. The Dark Energy Survey: Prospects for Resolved Stellar Populations

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

    Rossetto, Bruno M [Rio de Janeiro Observ.; Santiago, Basilio X [Rio Grande do Sul U.; Rio de Janeiro Observ.; Girardi, Leo [Padua Observ.; Rio de Janeiro Observ.; Camargo, Julio I.B. [Rio de Janeiro Observ.; Balbinot, Eduardo [Rio Grande do Sul U.; Rio de Janeiro Observ.; da Costa, Luiz N [Rio de Janeiro Observ.; Yanny, Brian [Fermilab; Maia, Marcio A.G. [Rio de Janeiro Observ.; Makler, Martin [Rio de Janeiro, CBPF; Rio de Janeiro Observ.; Ogando, Ricardo L.C. [Rio de Janeiro Observ.; Pellegrini, Paulo S [Rio de Janeiro Observ.; Rio de Janeiro Observ.

    2011-05-06T23:59:59.000Z

    Wide angle and deep surveys, regardless of their primary purpose, always sample a large number of stars in the Galaxy and in its satellite system. We here make a forecast of the expected stellar sample resulting from the Dark Energy Survey and the perspectives that it will open for studies of Galactic structure and resolved stellar populations in general. An estimated 1.2 x 10{sup 8} stars will be sampled in DES grizY filters in the southern equatorial hemisphere. This roughly corresponds to 20% of all DES sources. Most of these stars belong to the stellar thick disk and halo of the Galaxy.

  8. THE PROGENITOR MASS OF SN 2011dh FROM STELLAR POPULATION ANALYSIS

    SciTech Connect (OSTI)

    Murphy, Jeremiah W.; Jennings, Zachary G.; Williams, Benjamin; Dalcanton, Julianne J. [Astronomy Department, University of Washington, Seattle, WA 98195 (United States); Dolphin, Andrew E., E-mail: jmurphy@astro.washington.edu, E-mail: adolphin@raytheon.com [Raytheon, 1151 E. Hermans Road, Tucson, AZ 85706 (United States)

    2011-11-20T23:59:59.000Z

    Using Hubble Space Telescope photometry, we characterize the age of the stellar association in the vicinity of supernova (SN) 2011dh and use it to infer the zero-age main-sequence mass (M{sub ZAMS}) of the progenitor star. We find two distinct and significant star formation (SF) events with ages of <6 and 17{sup +3}{sub -4} Myr, and the corresponding M{sub ZAMS} are >29 and 13{sup +2}{sub -1} M{sub Sun }, respectively. These two bursts represent 18{sup +4}{sub -9}% (young) and 64{sup +10}{sub -14}% (old) of the total SF in the last 50 Myr. Adopting these fractions as probabilities suggests that the most probable M{sub ZAMS} is 13{sup +2}{sub -1} M{sub Sun }. These results are most sensitive to the luminosity function along the well-understood main sequence (MS) and are less sensitive to uncertain late-stage stellar evolution. Therefore, they stand even if the progenitor suffered disruptive post-MS evolution (e.g., eruptive mass loss or binary Roche-lobe overflow). Progenitor identification will help to further constrain the appropriate population. Even though pre-explosion images show a yellow supergiant (YSG) at the site of the SN, panchromatic SN light curves suggest a more compact star as the progenitor. In spite of this, our results suggest an association between the YSG and the SN. Not only was the star located at the SN site, but reinforcing an association, the star's bolometric luminosity is consistent with the final evolutionary stage of the 17 Myr old starburst. If the YSG disappears, then M{sub ZAMS} = 13{sup +2}{sub -1} M{sub Sun }, but if it persists, then our results allow the possibility that the progenitor was an unseen star of >29 M{sub Sun }.

  9. Compact Imaging Spectrometer Utilizing Immersed Gratings

    DOE Patents [OSTI]

    Chrisp, Michael P. (Danville, CA); Lerner, Scott A. (Corvallis, OR); Kuzmenko, Paul J. (Livermore, CA); Bennett, Charles L. (Livermore, CA)

    2006-03-21T23:59:59.000Z

    A compact imaging spectrometer with an immersive diffraction grating that compensates optical distortions. The imaging spectrometer comprises an entrance slit for transmitting light, a system for receiving the light and directing the light, an immersion grating, and a detector array. The entrance slit, the system for receiving the light, the immersion grating, and the detector array are positioned wherein the entrance slit transmits light to the system for receiving the light and the system for receiving the light directs the light to the immersion grating and the immersion grating receives the light and directs the light through an optical element to the detector array.

  10. Raytheon's next generation compact inline cryocooler architecture

    SciTech Connect (OSTI)

    Schaefer, B. R.; Bellis, L.; Ellis, M. J.; Conrad, T. [Raytheon Space and Airborne Systems, 2000 E. El Segundo Blvd., El Segundo, CA 90245 (United States)

    2014-01-29T23:59:59.000Z

    Since the 1970s, Raytheon has developed, built, tested and integrated high performance cryocoolers. Our versatile designs for single and multi-stage cryocoolers provide reliable operation for temperatures from 10 to 200 Kelvin with power levels ranging from 50 W to nearly 600 W. These advanced cryocoolers incorporate clearance seals, flexure suspensions, hermetic housings and dynamic balancing to provide long service life and reliable operation in all relevant environments. Today, sensors face a multitude of cryocooler integration challenges such as exported disturbance, efficiency, scalability, maturity, and cost. As a result, cryocooler selection is application dependent, oftentimes requiring extensive trade studies to determine the most suitable architecture. To optimally meet the needs of next generation passive IR sensors, the Compact Inline Raytheon Stirling 1-Stage (CI-RS1), Compact Inline Raytheon Single Stage Pulse Tube (CI-RP1) and Compact Inline Raytheon Hybrid Stirling/Pulse Tube 2-Stage (CI-RSP2) cryocoolers are being developed to satisfy this suite of requirements. This lightweight, compact, efficient, low vibration cryocooler combines proven 1-stage (RS1 or RP1) and 2-stage (RSP2) cold-head architectures with an inventive set of warm-end mechanisms into a single cooler module, allowing the moving mechanisms for the compressor and the Stirling displacer to be consolidated onto a common axis and in a common working volume. The CI cryocooler is a significant departure from the current Stirling cryocoolers in which the compressor mechanisms are remote from the Stirling displacer mechanism. Placing all of the mechanisms in a single volume and on a single axis provides benefits in terms of package size (30% reduction), mass (30% reduction), thermodynamic efficiency (>20% improvement) and exported vibration performance (?25 mN peak in all three orthogonal axes at frequencies from 1 to 500 Hz). The main benefit of axial symmetry is that proven balancing techniques and hardware can be utilized to null all motion along the common axis. Low vibration translates to better sensor performance resulting in simpler, more direct mechanical mounting configurations, eliminating the need for convoluted, expensive, massive, long lead damping hardware.

  11. Charlton Compact Power Ltd | Open Energy Information

    Open Energy Info (EERE)

    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: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand JumpConceptual Model, click here.Telluric Survey asWest,CEICharlotte County, Virginia:Vermont:Compact

  12. Compact Power Inc CPI | Open Energy Information

    Open Energy Info (EERE)

    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: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand JumpConceptual Model, clickInformationNew York:GovernorCommons Capital JumpCompact Power Inc CPI

  13. Stellar and dynamical evolution within triple systems

    E-Print Network [OSTI]

    P. P. Eggleton; L. G. Kiseleva

    1995-10-20T23:59:59.000Z

    About 5-15% of stellar systems are at least triple. About 1% of systems with a primary of $\\tgs 1 \\Mscun$ are triple with a {\\it longer} peri od that is less than 30y, and so may in principle be capable of Roche-lobe overflow in both the inner and the outer orbits, at different times. We discuss possible evolutionary paths for these systems, some of which may lead to objects that are difficult to understand in the context of purely binary evolution. An example is OW Gem, a binary containing two supergiants (spectral types F and G) with masses that difffer by a factor of 1.5. There is also a triple-star pathway which could lead rather naturally to low-mass X-ray binaries; whereas binary pathways often appear rather contrived. We also discuss some dynamical pr ocesses involved in the 3-body problem. A number of triple stars are found in clusters. Similar systems can be created by gravitational capture during N-body simulations of Galactic clusters, especially if there is a n assumed primordial binary population. We discuss the properties of these triples , and note that many can be quite long-lived.

  14. On the formation of massive stellar clusters

    E-Print Network [OSTI]

    Tenorio-Tagle, G; Silich, S A; Medina-Tanco, G A; Muñoz-Tunón, C; Tenorio-Tagle, Guillermo; Palous, Jan; Silich, Sergiy; Medina-Tanco, Gustavo A.; Munoz-Tunon, Casiana

    2003-01-01T23:59:59.000Z

    Here we model a star forming factory in which the continuous creation of stars results in a highly concentrated, massive (globular cluster-like) stellar system. We show that under very general conditions a large-scale gravitational instability in the ISM, which triggers the collapse of a massive cloud, leads with the aid of a spontaneous first generation of massive stars, to a standing, small-radius, cold and dense shell. Eventually, as more of the collapsing matter is processed and incorporated, the shell becomes gravitationally unstable and begins to fragment, allowing the formation of new stars, while keeping its location. This is due to a detailed balance established between the ram pressure from the collapsing cloud which, together with the gravitational force exerted on the shell by the forming cluster, acts against the mechanical energy deposited by the collection of new stars. We analyze the mass spectrum of fragments that result from the continuous fragmentation of the standing shell and show that it...

  15. Design studies of low aspect ratio quasi-omnigenous stellarators

    E-Print Network [OSTI]

    Martín-Solís, José Ramón

    optimization principles for the design of a more attractive reactor. These are 3 and 4 field period low aspect] produced low aspect ratio stellarator configurations that had promising features for a reactor (stable

  16. $\\beta$-decay of key titanium isotopes in stellar environment

    E-Print Network [OSTI]

    Nabi, Jameel-Un; 10.1142/S0218301311018174

    2011-01-01T23:59:59.000Z

    Amongst iron regime nuclei, $\\beta$-decay rates on titanium isotopes are considered to be important during the late phases of evolution of massive stars. The key $\\beta$-decay isotopes during presupernova evolution were searched from available literature and a microscopic calculation of the decay rates were performed using the proton-neutron quasiparticle random phase approximation (pn-QRPA) theory. As per earlier simulation results electron capture and $\\beta$-decay on certain isotopes of titanium are considered to be important for the presupernova evolution of massive stars. Earlier the stellar electron capture rates and neutrino energy loss rates due to relevant titanium isotopes were presented. In this paper we finally present the $\\beta$-decay rates of key titanium isotopes in stellar environment. The results are also compared against previous calculations. The pn-QRPA $\\beta$-decay rates are bigger at high stellar temperatures and smaller at high stellar densities compared to the large scale shell model...

  17. Discovery of the high--ionization emission line [Ne V] 3426 in the blue compact dwarf galaxy Tol 1214-277

    E-Print Network [OSTI]

    Y. I. Izotov; K. G. Noeske; N. G. Guseva; P. Papaderos; T. X. Thuan; K. J. Fricke

    2004-01-10T23:59:59.000Z

    The discovery of the high-ionization [Ne V] 3426A emission line in the spectrum of the blue compact dwarf (BCD) galaxy Tol 1214-277 is reported. The detection of this line implies the presence of intense ionizing X-ray emission with a luminosity in the range 10^39-10^40 erg/s. Such a high X-ray luminosity cannot be reproduced by models of massive stellar populations. Other mechanisms, such as fast shocks or accretion of gas in high-mass X-ray binaries need to be invoked to account for the high intensity of the [Ne V] 3426A emission line.

  18. On the universality of luminosity-metallicity and mass-metallicity relations for compact star-forming galaxies at redshifts 0 < z < 3

    E-Print Network [OSTI]

    Izotov, Y I; Fricke, K J; Henkel, C

    2015-01-01T23:59:59.000Z

    We study relations between global characteristics of low-redshift (0 1. These data were combined with the corresponding data for high-redshift (2 < z < 3) star-forming galaxies. We find that in all diagrams low-z and high-z star-forming galaxies are closely related indicating a very weak dependence of metallicity on stellar mass, redshift, and star-formation rate. This finding argues in favour of the universal character of the global relations for compact star-forming galaxies with high-excitation HII regions over redshifts 0 < z < 3.

  19. Determination of the stellar (n,$\\gamma$) cross section of $^{54}Fe$ with accelerator mass spectrometry

    E-Print Network [OSTI]

    Coquard, L; Dillmann, I; Wallner, A; Knie, K; Kutschera, W

    2006-01-01T23:59:59.000Z

    Determination of the stellar (n,$\\gamma$) cross section of $^{54}Fe$ with accelerator mass spectrometry

  20. Merger rates of double neutron stars and stellar origin black holes: The Impact of Initial Conditions on Binary Evolution Predictions

    E-Print Network [OSTI]

    de Mink, S E

    2015-01-01T23:59:59.000Z

    The initial mass function (IMF), binary fraction and distributions of binary parameters (mass ratios, separations and eccentricities) are indispensable input for simulations of stellar populations. It is often claimed that these are poorly constrained significantly affecting evolutionary predictions. Recently, dedicated observing campaigns provided new constraints on the initial conditions for massive stars. Findings include a larger close binary fraction and a stronger preference for very tight systems. We investigate the impact on the predicted merger rates of neutron stars and black holes. Despite the changes with previous assumptions, we only find an increase of less than a factor 2 (insignificant compared with evolutionary uncertainties of typically a factor 10-100). We further show that the uncertainties in the new initial binary properties do not significantly affect (within a factor of 2) our predictions of double compact object merger rates. An exception is the uncertainty in IMF (variations by a fac...

  1. Design and initial operation of a two-color soft x-ray camera system on the Compact Toroidal Hybrid experiment

    SciTech Connect (OSTI)

    Herfindal, J. L., E-mail: j.herfindal@gmail.com; Dawson, J. D.; Ennis, D. A.; Hartwell, G. J.; Loch, S. D.; Maurer, D. A. [Physics Department, Auburn University, Auburn, Alabama 36849 (United States)

    2014-11-15T23:59:59.000Z

    A multi-camera soft x-ray diagnostic has been developed to measure the equilibrium electron temperature profile and temperature fluctuations due to magnetohydrodynamic activity on the Compact Toroidal Hybrid experiment. The diagnostic consists of three separate cameras each employing two 20-channel diode arrays that view the same plasma region through different beryllium filter thicknesses of 1.8??m and 3.0??m allowing electron temperature measurements between 50 eV and 200 eV. The Compact Toroidal Hybrid is a five-field period current-carrying stellarator, in which the presence of plasma current strongly modifies the rotational transform and degree of asymmetry of the equilibrium. Details of the soft x-ray emission, effects of plasma asymmetry, and impurity line radiation on the design and measurement of the two-color diagnostic are discussed. Preliminary estimates of the temperature perturbation due to sawtooth oscillations observed in these hybrid discharges are given.

  2. Compact solid source of hydrogen gas

    DOE Patents [OSTI]

    Kravitz, Stanley H.; Hecht, Andrew M.; Sylwester, Alan P.; Bell, Nelson S.

    2004-06-08T23:59:59.000Z

    A compact solid source of hydrogen gas, where the gas is generated by contacting water with micro-disperse particles of sodium borohydride in the presence of a catalyst, such as cobalt or ruthenium. The micro-disperse particles can have a substantially uniform diameter of 1-10 microns, and preferably about 3-5 microns. Ruthenium or cobalt catalytic nanoparticles can be incorporated in the micro-disperse particles of sodium borohydride, which allows a rapid and complete reaction to occur without the problems associated with caking and scaling of the surface by the reactant product sodium metaborate. A closed loop water management system can be used to recycle wastewater from a PEM fuel cell to supply water for reacting with the micro-disperse particles of sodium borohydride in a compact hydrogen gas generator. Capillary forces can wick water from a water reservoir into a packed bed of micro-disperse fuel particles, eliminating the need for using an active pump.

  3. Compact wavefunctions from compressed imaginary time evolution

    E-Print Network [OSTI]

    Jarrod R. McClean; Alán Aspuru-Guzik

    2014-09-25T23:59:59.000Z

    Simulation of quantum systems promises to deliver physical and chemical predictions for the frontiers of technology. Unfortunately, the exact representation of these systems is plagued by the exponential growth of dimension with the number of particles, or colloquially, the curse of dimensionality. The success of approximation methods has hinged on the relative simplicity of physical systems with respect to the exponentially complex worst case. Exploiting this relative simplicity has required detailed knowledge of the physical system under study. In this work, we introduce a general and efficient black box method for many-body quantum systems that utilizes technology from compressed sensing to find the most compact wavefunction possible without detailed knowledge of the system. It is a Multicomponent Adaptive Greedy Iterative Compression (MAGIC) scheme. No knowledge is assumed in the structure of the problem other than correct particle statistics. This method can be applied to many quantum systems such as spins, qubits, oscillators, or electronic systems. As an application, we use this technique to compute ground state electronic wavefunctions of hydrogen fluoride and recover 98% of the basis set correlation energy or equivalently 99.996% of the total energy with $50$ configurations out of a possible $10^7$. Building from this compactness, we introduce the idea of nuclear union configuration interaction for improving the description of reaction coordinates and use it to study the dissociation of hydrogen fluoride and the helium dimer.

  4. ROSAT Observations of Compact Groups of Galaxies

    E-Print Network [OSTI]

    P. Saracco; P. Ciliegi

    1994-12-15T23:59:59.000Z

    A search for X-ray emission from compact groups revealed detection from 8 out of the 12 HCG images extracted from the ROSAT public archive. For two of them the X-ray emission originates from galaxies in the group. On the contrary, three groups show an extended emission clearly caused by hot intracluster gas. A Raymond-Smith hot plasma model provides an excellent fit to the X-ray spectra. The estimated temperatures are distributed in a quite narrow range (from 0.73 to 0.92 keV) and are consistent, within the errors, with 0.9 keV. The luminosity ranging from 0.75 to $5.1\\cdot10^{42}$erg s$^{-1}$. The most relevant result is the low metal abundance surely detected in two of them and likely in a third that characterizes the hot gas cloud responsible for the X-ray emission. The data concerning the remaining 3 detected compact groups are not sufficient to discriminate with certainty between diffuse and/or point-like X-ray emission. However the results of the spectral analysis point to the presence of a hot gas again with low metal abundance.

  5. Compact reactor/ORC power source

    SciTech Connect (OSTI)

    Meier, K.L.; Kirchner, W.L.; Willcutt, G.J.

    1986-01-01T23:59:59.000Z

    A compact power source that combines an organic Rankine Cycle (ORC) electric generator with a nuclear reactor heat source is being designed and fabricated. Incorporating existing ORC technology with proven reactor technology, the compact reactor/ORC power source offers high reliability while minimizing the need for component development. Thermal power at 125 kWt is removed from the coated particle fueled, graphite moderated reactor by heat pipes operating at 500/sup 0/C. Outside the reactor vessel and connected to the heat pipes are vaporizers in which the toluene ORC working fluid is heated to 370/sup 0/C. In the turbine-alternator-pump (TAP) combined-rotating unit, the thermal energy of the toluene is converted to 25 kWe of electric power. Lumped parameter systems analyses combined with a finite element thermal analysis have aided in the power source design. The analyses have provided assurance of reliable multiyear normal operation as well as full power operation with upset conditions, such as failed heat pipes and inoperative ORC vaporizers. Because of inherent high reliability, long life, and insensitivity to upset conditions, this power source is especially suited for use in remote, inaccessible locations where fuel delivery and maintenance costs are high. 10 refs.

  6. Tidal deformations of a spinning compact object

    E-Print Network [OSTI]

    Paolo Pani; Leonardo Gualtieri; Andrea Maselli; Valeria Ferrari

    2015-03-25T23:59:59.000Z

    The deformability of a compact object induced by a perturbing tidal field is encoded in the tidal Love numbers, which depend sensibly on the object's internal structure. These numbers are known only for static, spherically-symmetric objects. As a first step to compute the tidal Love numbers of a spinning compact star, here we extend powerful perturbative techniques to compute the exterior geometry of a spinning object distorted by an axisymmetric tidal field to second order in the angular momentum. The spin of the object introduces couplings between electric and magnetic deformations and new classes of induced Love numbers emerge. For example, a spinning object immersed in a quadrupolar, electric tidal field can acquire some induced mass, spin, quadrupole, octupole and hexadecapole moments to second order in the spin. The deformations are encoded in a set of inhomogeneous differential equations which, remarkably, can be solved analytically in vacuum. We discuss certain subtleties in defining the multipole moments of the central object, which are due to the difficulty in separating the tidal field from the linear response of the object in the solution. By extending the standard procedure to identify the linear response in the static case, we prove analytically that the Love numbers of a Kerr black hole remain zero to second order in the spin. As a by-product, we provide the explicit form for a slowly-rotating, tidally-deformed Kerr black hole to quadratic order in the spin, and discuss its geodesic and geometrical properties.

  7. Compaction of Norphlet sandstones, Rankin County, Mississippi

    SciTech Connect (OSTI)

    McBride, E.F.

    1987-09-01T23:59:59.000Z

    Fabric and porosity changes resulting from compaction were studied in sandstones from three cores sampled at depths between 15,900 and 22,500 ft. Point counts of 30 thin sections indicate that 0.4% of the rock volume was lost by ductile grain deformation and 3% by pressure solution at both grain contacts and at widely spaced stylolites. Pre-cement porosities of eolian sandstone range from 27 to 35% (mean = 29%), indicating that a total of from 10 to 18% porosity (mean = 16%) was lost by compaction (assuming 45% initial porosity). The difference between the total porosity loss and the sum of the other two processes is assumed to be the porosity lost by grain rearrangement (mean = 12.6%). The amount of pressure solution at grain contacts for each well is independent of depth, temperature, and amount of both quartz cement and total cement. Stylolites transect both grains and cements, which indicates they formed late in the diagenetic sequence. Silica released by pressure solution at quartz grain contacts could not be the sole source and was probably not even the major source of quartz cement in the formation, because cementation by quartz preceded the episode of strong pressure solution. In addition, the volume of silica released by pressure solution appears to have been inadequate to provide the volume of quartz cement present.

  8. Compact Stirling cooling of astronomical detectors

    E-Print Network [OSTI]

    Raskin, Gert; Pessemier, Wim; Padilla, Jesus Perez; Vandersteen, Jeroen

    2013-01-01T23:59:59.000Z

    MAIA, a three-channel imager targeting fast cadence photometry, was recently installed on the Mercator telescope (La Palma, Spain). This instrument observes a 9.4 x 14.1 arcmin field of view simultaneously in three color bands ($u$, $g$ and $r$), using three of the largest (un-) available frame-transfer CCDs, namely the 2k x 6k CCD42-C0 from e2v. As these detectors are housed in three separate cryostats, compact cooling devices are required that offer sufficient power to cool the large chips to a temperature of 165K. We explored a broad spectrum of cooling options and technologies to cool the MAIA detectors. Finally, compact free-piston Stirling coolers were selected, namely the CryoTel MT cryo-coolers from SUNPOWER, that can extract 5W of heat at a temperature of 77K. In this contribution we give details of the MAIA detector cooling solution. We also discuss the general usability of this type of closed-cycle cryo-coolers for astronomical detectors. They offer distinct advantages but the vibrations caused by ...

  9. AGN Jet Mass Loading and Truncation by Stellar Winds

    E-Print Network [OSTI]

    Alexander Hubbard; Eric G. Blackman

    2006-04-28T23:59:59.000Z

    Active Galactic Nuclei can produce extremely powerful jets. While tightly collimated, the scale of these jets and the stellar density at galactic centers implies that there will be many jet/star interactions, which can mass-load the jet through stellar winds. Previous work employed modest wind mass outflow rates, but this does not apply when mass loading is provided by a small number of high mass-loss stars. We construct a framework for jet mass-loading by stellar winds for a broader spectrum of wind mass-loss rates than has been previously considered. Given the observed stellar mass distributions in galactic centers, we find that even highly efficient (0.1 Eddington luminosity) jets from supermassive black holes of masses $M_{BH} \\la 10^4M_{\\odot}$ are rapidly mass loaded and quenched by stellar winds. For $10^4 M_{\\odot}jets is independent of the jet's mechanical luminosity. Stellar wind mass-loading is unable to quench efficient jets from more massive engines, but can account for the observed truncation of the inefficient M87 jet, and implies a baryon dominated composition on scales $\\ga 2$ kpc therein even if the jet is initially pair plasma dominated.

  10. Development of a folded compact range and its application in performing coherent change detection and interferometric ISAR measurement

    SciTech Connect (OSTI)

    Sorensen, K.W.; Zittel, D.H. [Sandia National Labs., Albuquerque, NM (United States); Littlejohn, J.H. [Geo-Centers, Inc., Albuquerque, NM (United States)

    1996-09-01T23:59:59.000Z

    A folded compact range configuration has been developed at the Sandia National Laboratories` compact range antenna and radar cross section measurement facility as a means of performing indoor, environmentally controlled far-field simulations of synthetic aperture radar (SAR) measurements of distributed target samples (i.e. gravel, sand, etc.). In particular, the folded compact range configuration has been used to perform both highly sensitive coherent change detection (CCD) measurements and interferometric inverse synthetic aperture radar (IFSAR) measurements, which, in addition to the two-dimensional spatial resolution afforded by typical interferometric SAR (ISAR) processing, provides resolution of the relative height of targets with accuracies on the order of a wavelength. This paper describes the development of the folded compact range, as well as the coherent change detection and interferometric measurements that have been made with the system. The measurement have been very successful, and have demonstrated not only the viability of the folded compact range concept in simulating SAR CCD and IFSAR measurements, but also its usefulness as a tool in the research and development of SAR CCD and IFSAR image generation and measurement methodologies.

  11. advanced compact accelerator: Topics by E-print Network

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

    of suitable neutron sources that are compactible with installation in a hospital enviroment. A low-energy accelerator-based neutron source has the potential for meeting...

  12. Compact heat exchangers for condensation applications: Yesterday, today and tomorrow

    SciTech Connect (OSTI)

    Panchal, C.B.

    1993-07-01T23:59:59.000Z

    Compact heat exchangers are being increasingly considered for condensation applications in the process, cryogenic, aerospace, power and refrigeration industries. In this paper, different configurations available for condensation applications are analyzed and the current state-of-the-knowledge for the design of compact condensers is evaluated. The key technical issues for the design and development of compact heat exchangers for condensation applications are analyzed and major advantages are identified. The experimental data and performance prediction methods reported in the literature are analyzed to evaluate the present design capabilities for different compact heat-exchanger configurations. The design flexibility is evaluated for the development of new condensation applications, including integration with other process equipment.

  13. Poroelastic damage rheology: Dilation, compaction, and failure of rocks

    E-Print Network [OSTI]

    Lyakhovsky, Vladimir

    Poroelastic damage rheology: Dilation, compaction, and failure of rocks Yariv Hamiel Institute December 2004; Published 26 January 2005. Hamiel, Y., V. Lyakhovsky, and A. Agnon (2005), Poroelastic

  14. Development, Test and Demonstration of a Cost-Effective, Compact...

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

    taylor.pdf More Documents & Publications Development, Test and Demonstration of a Cost-Effective, Compact, Light-Weight, and Scalable High Temperature Inverter for HEVs, PHEVs, and...

  15. accreting compact stars: Topics by E-print Network

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

    of the millisecond brightness oscillations from low mass X-ray binaries during thermonuclear bursts can provide us with important information about compact star parameters....

  16. Appalachian States Low-Level Radioactive Waste Compact (Maryland)

    Broader source: Energy.gov [DOE]

    This legislation authorizes Maryland's entrance into the Appalachian States Low-Level Radioactive Waste Compact, which seeks to promote interstate cooperation for the proper management and disposal...

  17. Cape Light Compact- Residential Energy Efficiency Rebate Program

    Broader source: Energy.gov [DOE]

    Cape Light Compact (CLC) offers a variety of financial incentives to customers for purchasing energy efficient residential equipment. Residential customers can take advantage of incentives on...

  18. Western Interstate Nuclear Compact State Nuclear Policy (Multiple States)

    Broader source: Energy.gov [DOE]

    Legislation authorizes states' entrance into the Western Interstate Nuclear Compact, which aims to undertake the cooperation of participating states in deriving the optimum benefit from nuclear and...

  19. Southwestern Low-Level Radioactive Waste Disposal Compact (South Dakota)

    Broader source: Energy.gov [DOE]

    This legislation authorizes the state's entrance into the Southwestern Low-Level Radioactive Waste Disposal Compact, which provides for the cooperative management of low-level radioactive waste....

  20. Old stellar populations in distant radio galaxies

    E-Print Network [OSTI]

    James Dunlop

    1998-01-13T23:59:59.000Z

    I describe the current status of our attempts to determine the age of the oldest known stellar populations at high redshift, in the red mJy radio galaxies 53W091 ($z = 1.55$) and 53W069 ($z = 1.43$). During the past year the original conclusion of Dunlop et al. (1996) - that 53W091 is $>3$ Gyr old - has been questioned from two, basically orthogonal directions. First, reports that the near-infrared light from 53W091 is highly polarized have cast some doubt on whether its red colour is genuinely due to an old population of stars. Second, assuming that all the light is indeed due to stars, it has been claimed that 53W091 is in fact only 1-2 Gyr old. Here I present a preliminary analysis of new infrared polarimetric observations of 53W091 which show that the first of these criticisms can be rejected with very high confidence. I then explore why different modellers have derived different ages for 53W091, and present new model fits to the spectrum of 53W069 which demonstrate that different spectral synthesis codes are certainly in good agreement that this galaxy is 3-4 Gyr old. Finally I present a preliminary analysis of the morphologies and scale-lengths of 53W091 and 53W069 as derived from new I-band WFPC2 HST images, and compare the results with those for 3CR galaxies at comparable redshifts. I conclude that the scalelengths and luminosities of radio galaxies at $z \\simeq 1.5$ appear to scale together as would be predicted from the Kormendy relation for low-redshift elliptical galaxies.

  1. Early hydrodynamic evolution of a stellar collision

    SciTech Connect (OSTI)

    Kushnir, Doron; Katz, Boaz [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States)

    2014-04-20T23:59:59.000Z

    The early phase of the hydrodynamic evolution following the collision of two stars is analyzed. Two strong shocks propagate from the contact surface and move toward the center of each star at a velocity that is a small fraction of the velocity of the approaching stars. The shocked region near the contact surface has a planar symmetry and a uniform pressure. The density vanishes at the (Lagrangian) surface of contact, and the speed of sound diverges there. The temperature, however, reaches a finite value, since as the density vanishes, the finite pressure is radiation dominated. For carbon-oxygen white dwarf (CO WD) collisions, this temperature is too low for any appreciable nuclear burning shortly after the collision, which allows for a significant fraction of the mass to be highly compressed to the density required for efficient {sup 56}Ni production in the detonation wave that follows. This property is crucial for the viability of collisions of typical CO WD as progenitors of type Ia supernovae, since otherwise only massive (>0.9 M {sub ?}) CO WDs would have led to such explosions (as required by all other progenitor models). The divergence of the speed of sound limits numerical studies of stellar collisions, as it makes convergence tests exceedingly expensive unless dedicated schemes are used. We provide a new one-dimensional Lagrangian numerical scheme to achieve this. A self-similar planar solution is derived for zero-impact parameter collisions between two identical stars, under some simplifying assumptions (including a power-law density profile), which is the planar version of previous piston problems that were studied in cylindrical and spherical symmetries.

  2. On the formation of massive stellar clusters

    E-Print Network [OSTI]

    Guillermo Tenorio-Tagle; Jan Palous; Sergiy Silich; Gustavo A. Medina-Tanco; Casiana Munoz-Tunon

    2003-08-25T23:59:59.000Z

    Here we model a star forming factory in which the continuous creation of stars results in a highly concentrated, massive (globular cluster-like) stellar system. We show that under very general conditions a large-scale gravitational instability in the ISM, which triggers the collapse of a massive cloud, leads with the aid of a spontaneous first generation of massive stars, to a standing, small-radius, cold and dense shell. Eventually, as more of the collapsing matter is processed and incorporated, the shell becomes gravitationally unstable and begins to fragment, allowing the formation of new stars, while keeping its location. This is due to a detailed balance established between the ram pressure from the collapsing cloud which, together with the gravitational force exerted on the shell by the forming cluster, acts against the mechanical energy deposited by the collection of new stars. We analyze the mass spectrum of fragments that result from the continuous fragmentation of the standing shell and show that its shape is well approximated at the high mass end by a power law with slope -2.25, very close to the value that fits the universal IMF. The self-contamination resultant from the continuous generation of stars is shown to lead to a large metal spread in massive ($\\sim$ 10$^6$ M$_\\odot$) clusters, while clusters with a mass similar to 10$^5$ M$_\\odot$ or smaller, simply reflect the initial metalicity of the collapsing cloud. This is in good agreement with the data available for globular clusters in the Galaxy.

  3. Conservation potential of compact fluorescent lamps in India and Brazil

    SciTech Connect (OSTI)

    Gadgil, A.; Martino Jannuzzi, G. de (Lawrence Berkeley Lab., CA (USA); Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia)

    1989-07-01T23:59:59.000Z

    We evaluate the conservation potential of compact fluorescent lamps (CFLs) for managing the rapidly increasing electrical energy and peak demand in India and Brazil. Using very conservative assumptions, we find that the cost of conserved energy using 16 W CFLs is 4 and 6 times less than the long range marginal cost of electricity for the two countries. The cost of avoided peak installed capacity is 6 and 9.5 times less than the cost of new installed capacity for India and Brazil. The analysis is undertaken from the three separate perspectives of the national economies, the consumers, and the utilities. We find that because residential electricity is subsidized, the consumers have little or no incentive to purchase and install the CFLs, unless they too are subsidized. However, the benefits of CFL installation to the utility are so large that subsidizing them is a paying proposition for the utility are so large that subsidizing them is a paying proposition for the utility in almost all cases. As an illustration of a gradual introduction strategy for CFLs, we calculate a scenario where national savings of the order of US $1.2 million per day for India and US $2.5 million per day for Brazil are reached in 10 years by a small and gradual transfer of subsidy from residential electricity to CFLs. We then explore the barriers to immediate large scale introduction of these lamps in the two countries. Specific technical and marketing problems are identified and discussed, which would require solution before such an introduction can be attempted. Lastly, we discuss the range of policy instruments, in addition to a subsidy scheme, that can be used for promoting the diffusion of these lamps in the domestic and commercial sector. 47 refs., 15 figs., 2 tabs.

  4. Globalization Nationalized

    E-Print Network [OSTI]

    Mazlish, Bruce

    Globalism and globalization have been seen as competitors to other allegiances, namely regionalism and nationalism. A look at recent efforts at reconceptualizing global history in China, Korea and the U.S., however, suggests ...

  5. Compact conscious animal positron emission tomography scanner

    DOE Patents [OSTI]

    Schyler, David J. (Bellport, NY); O'Connor, Paul (Bellport, NY); Woody, Craig (Setauket, NY); Junnarkar, Sachin Shrirang (Sound Beach, NY); Radeka, Veljko (Bellport, NY); Vaska, Paul (Sound Beach, NY); Pratte, Jean-Francois (Stony Brook, NY); Volkow, Nora (Chevy Chase, MD)

    2006-10-24T23:59:59.000Z

    A method of serially transferring annihilation information in a compact positron emission tomography (PET) scanner includes generating a time signal for an event, generating an address signal representing a detecting channel, generating a detector channel signal including the time and address signals, and generating a composite signal including the channel signal and similarly generated signals. The composite signal includes events from detectors in a block and is serially output. An apparatus that serially transfers annihilation information from a block includes time signal generators for detectors in a block and an address and channel signal generator. The PET scanner includes a ring tomograph that mounts onto a portion of an animal, which includes opposing block pairs. Each of the blocks in a block pair includes a scintillator layer, detection array, front-end array, and a serial encoder. The serial encoder includes time signal generators and an address signal and channel signal generator.

  6. Compact and highly efficient laser pump cavity

    DOE Patents [OSTI]

    Chang, Jim J. (Dublin, CA); Bass, Isaac L. (Castro Valley, CA); Zapata, Luis E. (Livermore, CA)

    1999-01-01T23:59:59.000Z

    A new, compact, side-pumped laser pump cavity design which uses non-conventional optics for injection of laser-diode light into a laser pump chamber includes a plurality of elongated light concentration channels. In one embodiment, the light concentration channels are compound parabolic concentrators (CPC) which have very small exit apertures so that light will not escape from the pumping chamber and will be multiply reflected through the laser rod. This new design effectively traps the pump radiation inside the pump chamber that encloses the laser rod. It enables more uniform laser pumping and highly effective recycle of pump radiation, leading to significantly improved laser performance. This new design also effectively widens the acceptable radiation wavelength of the diodes, resulting in a more reliable laser performance with lower cost.

  7. Cooldown of the Compact Ignition Tokamak

    SciTech Connect (OSTI)

    Keeton, D.C.

    1987-08-01T23:59:59.000Z

    Cooldown of the Compact Ignition Tokamak (CIT) with the baseline liquid nitrogen cooling system was analyzed. On the basis of this analysis and present knowledge of the two-phase heat transfer, the current baseline CIT can be cooled down in about 1.5 h. An extensive heat transfer test program is recommended to reduce uncertainty in the heat transfer performance and to explore methods for minimizing the cooldown time. An alternate CIT cooldown system is described which uses a pressurized gaseous helium coolant in a closed-loop system. It is shown analytically that this system will cool down the CIT well within 1 h. Confidence in this analysis is sufficiently high that a heat transfer test program would not be necessary. The added cost of this alternate system is estimated to be about $5.3 million. This helium cooling system represents a reasonable backup approach to liquid nitrogen cooling of the CIT. 3 refs., 12 figs., 3 tabs.

  8. Collective Deceleration: Toward a Compact Beam Dump

    SciTech Connect (OSTI)

    Wu, H.-C.; /Munich, Max Planck Inst. Quantenopt.; Tajima, T.; Habs, D.; /Munich, Max Planck Inst. Quantenopt. /Munich U.; Chao, A.W.; /SLAC; Meyer-ter-Vehn, J.; /Munich, Max Planck Inst. Quantenopt.

    2011-11-28T23:59:59.000Z

    With the increasing development of laser accelerators, the electron energy is already beyond GeV and even higher in near future. Conventional beam dump based on ionization or radiation loss mechanism is cumbersome and costly, also has radiological hazards. We revisit the stopping power of high-energy charged particles in matter and discuss the associated problem of beam dump from the point of view of collective deceleration. The collective stopping length in an ionized gas can be several orders of magnitude shorter than the Bethe-Bloch and multiple electromagnetic cascades stopping length in solid. At the mean time, the tenuous density of the gas makes the radioactivation negligible. Such a compact and non-radioactivating beam dump works well for short and dense bunches, which is typically generated from laser wakefield accelerator.

  9. Compact hydrogen/helium isotope mass spectrometer

    DOE Patents [OSTI]

    Funsten, Herbert O. (Los Alamos, NM); McComas, David J. (Los Alamos, NM); Scime, Earl E. (Morgantown, WV)

    1996-01-01T23:59:59.000Z

    The compact hydrogen and helium isotope mass spectrometer of the present invention combines low mass-resolution ion mass spectrometry and beam-foil interaction technology to unambiguously detect and quantify deuterium (D), tritium (T), hydrogen molecule (H.sub.2, HD, D.sub.2, HT, DT, and T.sub.2), .sup.3 He, and .sup.4 He concentrations and concentration variations. The spectrometer provides real-time, high sensitivity, and high accuracy measurements. Currently, no fieldable D or molecular speciation detectors exist. Furthermore, the present spectrometer has a significant advantage over traditional T detectors: no confusion of the measurements by other beta-emitters, and complete separation of atomic and molecular species of equivalent atomic mass (e.g., HD and .sup.3 He).

  10. Compact high voltage solid state switch

    DOE Patents [OSTI]

    Glidden, Steven C.

    2003-09-23T23:59:59.000Z

    A compact, solid state, high voltage switch capable of high conduction current with a high rate of current risetime (high di/dt) that can be used to replace thyratrons in existing and new applications. The switch has multiple thyristors packaged in a single enclosure. Each thyristor has its own gate drive circuit that circuit obtains its energy from the energy that is being switched in the main circuit. The gate drives are triggered with a low voltage, low current pulse isolated by a small inexpensive transformer. The gate circuits can also be triggered with an optical signal, eliminating the trigger transformer altogether. This approach makes it easier to connect many thyristors in series to obtain the hold off voltages of greater than 80 kV.

  11. Compact imaging spectrometer utilizing immersed gratings

    DOE Patents [OSTI]

    Chrisp, Michael P. (Danville, CA); Lerner, Scott A. (Corvallis, OR); Kuzmenko, Paul J. (Livermore, CA); Bennett, Charles L. (Livermore, CA)

    2007-07-03T23:59:59.000Z

    A compact imaging spectrometer with an immersive diffraction grating that compensates optical distortions. The imaging spectrometer comprises an entrance slit for transmitting light, means for receiving the light and directing the light, an immersion grating, and a detector array. The entrance slit, the means for receiving the light, the immersion grating, and the detector array are positioned wherein the entrance slit transmits light to the means for receiving the light and the means for receiving the light directs the light to the immersion grating and the immersion grating receives the light and directs the light to the means for receiving the light, and the means for receiving the light directs the light to the detector array.

  12. Compact microwave ion source for industrial applications

    SciTech Connect (OSTI)

    Cho, Yong-Sub; Kim, Dae-Il; Kim, Han-Sung; Seol, Kyung-Tae; Kwon, Hyeok-Jung; Hong, In-Seok [Proton Engineering Frontier Project, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of)

    2012-02-15T23:59:59.000Z

    A 2.45 GHz microwave ion source for ion implanters has many good properties for industrial application, such as easy maintenance and long lifetime, and it should be compact for budget and space. But, it has a dc current supply for the solenoid and a rf generator for plasma generation. Usually, they are located on high voltage platform because they are electrically connected with beam extraction power supply. Using permanent magnet solenoid and multi-layer dc break, high voltage deck and high voltage isolation transformer can be eliminated, and the dose rate on targets can be controlled by pulse duty control with semiconductor high voltage switch. Because the beam optics does not change, beam transfer components, such as focusing elements and beam shutter, can be eliminated. It has shown the good performances in budget and space for industrial applications of ion beams.

  13. Stirling Air Conditioner for Compact Cooling

    SciTech Connect (OSTI)

    None

    2010-09-01T23:59:59.000Z

    BEETIT Project: Infinia is developing a compact air conditioner that uses an unconventional high efficient Stirling cycle system (vs. conventional vapor compression systems) to produce cool air that is energy efficient and does not rely on polluting refrigerants. The Stirling cycle system is a type of air conditioning system that uses a motor with a piston to remove heat to the outside atmosphere using a gas refrigerant. To date, Stirling systems have been expensive and have not had the right kind of heat exchanger to help cool air efficiently. Infinia is using chip cooling technology from the computer industry to make improvements to the heat exchanger and improve system performance. Infinia’s air conditioner uses helium gas as refrigerant, an environmentally benign gas that does not react with other chemicals and does not burn. Infinia’s improvements to the Stirling cycle system will enable the cost-effective mass production of high-efficiency air conditioners that use no polluting refrigerants.

  14. WHAT IS ON TAP? THE ROLE OF SPIN IN COMPACT OBJECTS AND RELATIVISTIC JETS

    SciTech Connect (OSTI)

    King, Ashley L.; Miller, Jon M.; Gueltekin, Kayhan [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States); Walton, Dominic J. [Space Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States); Fabian, Andrew C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 OHA (United Kingdom); Reynolds, Christopher S. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Nandra, Kirpaul, E-mail: ashking@umich.edu [Max Planck Institute for Extraterrestrial Physics, D-85741 Garching (Germany)

    2013-07-10T23:59:59.000Z

    We examine the role of spin in launching jets from compact objects across the mass scale. Our work includes 3 different Seyfert samples with a total of 37 unique Seyferts, as well as 11 stellar-mass black holes, and 13 neutron stars. We find that when the Seyfert reflection lines are modeled with simple Gaussian line features (a crude proxy for inner disk radius and therefore spin), only a slight inverse correlation is found between the Doppler-corrected radio luminosity at 5 GHz (a proxy for jet power) and line width. When the Seyfert reflection features are fit with more relativistically blurred disk reflection models that measure spin, there is a tentative positive correlation between the Doppler-corrected radio luminosity and the spin measurement. Further, when we include stellar-mass black holes in the sample, to examine the effects across the mass scale, we find a slightly stronger correlation with radio luminosity per unit mass and spin, at a marginal significance (2.3{sigma} confidence level). Finally, when we include neutron stars, in order to probe lower spin values, we find a positive correlation (3.3{sigma} confidence level) between radio luminosity per unit mass and spin. Although tentative, these results suggest that spin may have a role in determining the jet luminosity. In addition, we find a slightly more significant correlation (4.4{sigma} and 4.1{sigma} confidence level, respectively) between radio luminosity per bolometric luminosity and spin, as well as radio luminosity corrected for the fundamental plane (i.e., log ({nu}L{sub R}/L{sub Bol}{sup 0.67}/M{sub BH}{sup 0.78})) and spin, using our entire sample of black holes and neutrons stars. Again, although tentative, these relations point to the possibility that the mass accretion rate, i.e., bolometric luminosity, is also important in determining the jet luminosity, in addition to spin. Our analysis suggests that mass accretion rate and disk or coronal magnetic field strength may be the ''throttle'' in these compact systems, to which the Eddington limit and spin may set the maximum jet luminosity that can be achieved.

  15. Compact Fluorescent Lighting in America: Lessons Learned on the Way to Market

    SciTech Connect (OSTI)

    Sandahl, Linda J.; Gilbride, Theresa L.; Ledbetter, Marc R.; Steward, Heidi E.; Calwell, Chris

    2006-05-22T23:59:59.000Z

    This report describes the history of compact fluorescent lamps (CFLs) in America. CFLs were introduced in the 1970s; however, it has taken more than 20 years for them to gain widespread recognition in the U.S. residential lighting market. This report reviews the development of CFLs, efforts to increase market acceptance of them, and barriers to that acceptance. Lessons to be learned from this study of CFLs are identified in hopes of assisting future market introduction efforts for other promising energy-efficient technologies. This report was prepared by the Pacific Northwest National Laboratory for the U.S. Department of Energy’s Office of Building Technologies, Emerging Technologies Program.

  16. Microsoft Word - Compact Power_FinalEA_for concurrence 4-8-10.doc

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHighandSWPA / SPRA / USACE SWPAURTeC:8 3.After-Hoursof ChangingCOMPACT

  17. Synonymous Address Compaction for Energy Reduction in Data TLB

    E-Print Network [OSTI]

    Lee, Hsien-Hsin "Sean"

    Synonymous Address Compaction for Energy Reduction in Data TLB Chinnakrishnan S. Ballapuram chinnak and Computer Engineering College of Computing Georgia Institute of Technology, Atlanta, GA 30332 ABSTRACT-cycle compaction of address translation requests in order to save energy in the data TLB. Our results show

  18. compactness in transport theory Mustapha Mokhtar-Kharroubi

    E-Print Network [OSTI]

    Boyer, Edmond

    A main feature of spectra of transport operators in nuclear reactor theory relies on the compactness (orOn L1 compactness in transport theory Mustapha Mokhtar-Kharroubi Département de Mathématiques spectral theory of neutron transport equations on both n-dimensional torus and spatial domains with ...nite

  19. Compact Optical Technique for Streak Camera Calibration

    SciTech Connect (OSTI)

    Curt Allen; Terence Davies; Frans Janson; Ronald Justin; Bruce Marshall; Oliver Sweningsen; Perry Bell; Roger Griffith; Karla Hagans; Richard Lerche

    2004-04-01T23:59:59.000Z

    The National Ignition Facility is under construction at the Lawrence Livermore National Laboratory for the U.S. Department of Energy Stockpile Stewardship Program. Optical streak cameras are an integral part of the experimental diagnostics instrumentation. To accurately reduce data from the streak cameras a temporal calibration is required. This article describes a technique for generating trains of precisely timed short-duration optical pulses that are suitable for temporal calibrations.

  20. Magnetic Fields in High-Density Stellar Matter

    E-Print Network [OSTI]

    German Lugones

    2005-04-20T23:59:59.000Z

    I briefly review some aspects of the effect of magnetic fields in the high density regime relevant to neutron stars, focusing mainly on compact star structure and composition, superconductivity, combustion processes, and gamma ray bursts.

  1. CANDIDATES FOR THE YOUNG STELLAR OUTFLOWS: WATER AND METHANOL MASERS FROM YOUNG STELLAR OBJECTS

    SciTech Connect (OSTI)

    Lim, Wanggi; Lyo, A-Ran; Kim, Kee-Tae; Byun, Do-Young [Korea Astronomy and Space Science Institute, Daedeok Street 776, Yuseong-Gu, 305-348 Daejeon (Korea, Republic of)

    2012-11-01T23:59:59.000Z

    We conducted simultaneous 22 GHz water maser and 44 GHz class I methanol maser surveys of newly identified 282 H{sub 2} emission features from the 2.122 {mu}m H{sub 2} narrowband image survey in the Galactic plane (UWISH2 project) using Korean VLBI Network 21 m radio telescopes. We detected 16 and 13 new water and methanol maser sources, respectively. This result indicates that at least {approx}5% of the H{sub 2} emission features originate from young stellar objects (YSOs) that are in the right physical condition to produce the water and methanol masers. The masers are closely related to the current outflow activities in the Galactic plane. The power sources of these 23 diffused/collimated H{sub 2} emission features (six sources are detected for both masers) are likely to be intermediate- to high-mass YSOs, based on a comparison with the maser luminosities of other well-studied YSOs. Both maser velocities are mostly close to their own systemic velocities within {approx}<5 km s{sup -1}, even though water masers generally show larger variabilities in the intensity, velocity, and shape than methanol masers. We also discovered three new water maser sources with high-velocity components: {approx}25 km s{sup -1} redshifted CMHO 019, {approx}50 km s{sup -1} blueshifted CMHO 132, and {approx}120 km s{sup -1} blueshifted CMHO 182. In particular, we propose that the dominant blueshifted water maser of CHMO 182 can be a unique laboratory for the study of the high-mass young stellar jet and its acceleration.

  2. Maximum stellar mass versus cluster membership number revisited

    E-Print Network [OSTI]

    Th. Maschberger; C. J. Clarke

    2008-09-05T23:59:59.000Z

    We have made a new compilation of observations of maximum stellar mass versus cluster membership number from the literature, which we analyse for consistency with the predictions of a simple random drawing hypothesis for stellar mass selection in clusters. Previously, Weidner and Kroupa have suggested that the maximum stellar mass is lower, in low mass clusters, than would be expected on the basis of random drawing, and have pointed out that this could have important implications for steepening the integrated initial mass function of the Galaxy (the IGIMF) at high masses. Our compilation demonstrates how the observed distribution in the plane of maximum stellar mass versus membership number is affected by the method of target selection; in particular, rather low n clusters with large maximum stellar masses are abundant in observational datasets that specifically seek clusters in the environs of high mass stars. Although we do not consider our compilation to be either complete or unbiased, we discuss the method by which such data should be statistically analysed. Our very provisional conclusion is that the data is not indicating any striking deviation from the expectations of random drawing.

  3. MODEST: modeling stellar evolution and (hydro)dynamics

    E-Print Network [OSTI]

    Piet Hut

    2003-09-15T23:59:59.000Z

    Simulations of dense stellar systems currently face two major hurdles, one astrophysical and one computational. The astrophysical problem lies in the fact that several major stages in binary evolution, such as common envelope evolution, are still poorly understood. The best we can do in these cases is to parametrize our ignorance, in a way that is reminiscent of the introduction of a mixing length to describe convection in a single star, or an alpha parameter in modeling an accretion disk. The hope is that by modeling a whole star cluster in great detail, and comparing the results to the wealth of observational data currently available, we will be able to constrain the parameters that capture the unknown physics. The computational problem is one of composition: while we have accurate computer codes for modeling stellar dynamics, stellar hydrodynamics, and stellar evolution, we currently have no good way to put all this knowledge together in a single software environment. A year ago, a loosely-knit organization was founded to address these problems, MODEST for MOdeling DEnse STellar systems, with nine working groups and a series of meetings that are held every half year. This report reviews the first year of this initiative. Much more detail can be found on the MODEST web site http://www.manybody.org/modest.html .

  4. The Size of Compact Extra Dimensions from Blackbody Radiation Laws

    E-Print Network [OSTI]

    Ramaton Ramos; Henrique Boschi-Filho

    2014-04-28T23:59:59.000Z

    In this work we generalize the Stefan-Boltzmann and Wien's displacement laws for a $D$-dimensional manifold composed by 4 non-compact dimensions and $D-4$ compact dimensions, $ R^{1,3}$ x $T^{D-4} $. The electromagnetic field is assumed to pervade all compact and non-compact dimensions. In particular, the total radiated power becomes $ R(T) = \\sigma_B T^4 + \\sigma_D (a) \\, T^D $, where $a$ is the size of the compact extra dimensions. For $D=10$, predicted from String Theory, and $D=11$, from M-Theory, the outcomes agree with available experimental data for $a$ as high as 2 x $10^{-7}$m.

  5. Modeling compaction-induced energy dissipation of granular HMX

    SciTech Connect (OSTI)

    Gonthier, K.A. [Lamar Univ., Beaumont, TX (US). Dept. of Mechanical Engineering; Menikoff, R.; Son, S.F.; Asay, B.W. [Los Alamos National Lab., NM (US)

    1998-12-31T23:59:59.000Z

    A thermodynamically consistent model is developed for the compaction of granular solids. The model is an extension of the single phase limit of two-phase continuum models used to describe Deflagration-to-Detonation Transition (DDT) experiments. The focus is on the energetics and dissipation of the compaction process. Changes in volume fraction are partitioned into reversible and irreversible components. Unlike conventional DDT models, the model is applicable from the quasi-static to dynamic compaction regimes for elastic, plastic, or brittle materials. When applied to the compaction of granular HMX (a brittle material), the model predicts results commensurate with experiments including stress relaxation, hysteresis, and energy dissipation. The model provides a suitable starting point for the development of thermal energy localization sub-scale models based on compaction-induced dissipation.

  6. COMPACTION OF FIBERBOARD OVERPACK MATERIALS IN A 9975 SHIPPING PACKAGE

    SciTech Connect (OSTI)

    Stefek, T.; Daugherty, W.; Estochen, E.; Murphy, J.

    2010-05-27T23:59:59.000Z

    Compaction of lower layers in the 9975 fiberboard overpack has been observed in packages that contain excess moisture. Dynamic loading of the package during transportation may also contribute to compaction of the fiberboard. This condition is being tested and analyzed to better understand these compaction mechanisms and provide a basis from which to evaluate their impact to the safety basis for transportation (Safety Analysis Report for Packaging) and storage (facility Design Safety Analysis) at the Savannah River Site (SRS). A test program has been developed and is being implemented to identify the extent of the compaction as a function of fiberboard moisture and typical transport dynamic loadings. Test conditions will be compared to regulatory requirements for dynamic loading. Characterization of the recovery of short-term compaction following the application of dynamic loading is also being evaluated. Interim results from this test program will be summarized.

  7. Accretion-driven gravitational radiation from nonrotating compact objects. Infalling quadrupolar shells

    E-Print Network [OSTI]

    Alessandro Nagar; Guillermo Diaz; Jose A. Pons; Jose A. Font

    2004-06-29T23:59:59.000Z

    This paper reports results from numerical simulations of the gravitational radiation emitted from non--rotating compact objects(both neutron stars and Schwarzschild black holes) as a result of the accretion of matter. A hybrid procedure is adopted: we evolve, in axisymmetry, the linearized equations describing metric and fluid perturbations, coupled with a nonlinear hydrodynamics code that calculates the motion of the accreting matter. The initial matter distribution is shaped in the form of extended quadrupolar shells of dust or perfect fluid. Self--gravity and radiation reaction effects of the accreting fluid are neglected. This idealized setup is used to understand the qualitative features appearing in the energy spectrum of the gravitational wave emission from compact stars or black holes, subject to accretion processes involving extended objects. A comparison for the case of point--like particles falling radially onto black holes is also provided. Our results show that, when the central object is a black hole, the spectrum is far from having only one clear, monochromatic peak at the frequency of the fundamental quasi-normal mode, but it shows a complex pattern, with interference fringes produced by the interaction between the infalling matter and the underlying perturbed spacetime: most of the energy is emitted at frequencies lower than that of the fundamental mode of the black hole. Similar results are obtained for extended shells accreting onto neutron stars, but in this case the stellar fundamental mode is clearly excited. Our analysis shows that the gravitational wave signal driven by accretion is influenced more by the details and dynamics of the process, than by the quasi--normal mode structure of the central object.

  8. Gravitational waves from inspiralling compact binaries: hexagonal template placement and its efficiency in detecting physical signals

    E-Print Network [OSTI]

    Thomas Cokelaer

    2007-06-29T23:59:59.000Z

    Matched filtering is used to search for gravitational waves emitted by inspiralling compact binaries in data from the ground-based interferometers. One of the key aspects of the detection process is the design of a template bank that covers the astrophysically pertinent parameter space. In an earlier paper, we described a template bank that is based on a square lattice. Although robust, we showed that the square placement is over-efficient, with the implication that it is computationally more demanding than required. In this paper, we present a template bank based on an hexagonal lattice, which size is reduced by 40% with respect to the proposed square placement. We describe the practical aspects of the hexagonal template bank implementation, its size, and computational cost. We have also performed exhaustive simulations to characterize its efficiency and safeness. We show that the bank is adequate to search for a wide variety of binary systems (primordial black holes, neutron stars and stellar mass black holes) and in data from both current detectors (initial LIGO, Virgo and GEO600) as well as future detectors (advanced LIGO and EGO). Remarkably, although our template bank placement uses a metric arising from a particular template family, namely stationary phase approximation, we show that it can be used successfully with other template families (e.g., Pade resummation and effective one-body approximation). This quality of being effective for different template families makes the proposed bank suitable for a search that would use several of them in parallel (e.g., in a binary black hole search). The hexagonal template bank described in this paper is currently used to search for non-spinning inspiralling compact binaries in data from the Laser Interferometer Gravitational-Wave Observatory (LIGO).

  9. A New Four-Barrel Pellet Injection System for the TJ-II Stellarator

    SciTech Connect (OSTI)

    Combs, Stephen Kirk [ORNL] [ORNL; Foust, Charles R [ORNL] [ORNL; McGill, James M [ORNL] [ORNL; Baylor, Larry R [ORNL] [ORNL; Caughman, John B [ORNL] [ORNL; Fehling, Dan T [ORNL] [ORNL; Harris, Jeffrey H [ORNL] [ORNL; Meitner, Steven J [ORNL] [ORNL; Rasmussen, David A [ORNL] [ORNL; McCarthy, K. J. [EURATOM-CIEMAT, Madrid, Spain] [EURATOM-CIEMAT, Madrid, Spain; Chamorro, M. [Laboratory Nacional de Fusion, Madrid, Spain] [Laboratory Nacional de Fusion, Madrid, Spain; Garcia, R. [Laboratory Nacional de Fusion, Madrid, Spain] [Laboratory Nacional de Fusion, Madrid, Spain; Hildago, C. [Laboratory Nacional de Fusion, Madrid, Spain] [Laboratory Nacional de Fusion, Madrid, Spain; Medrano, M. [Laboratory Nacional de Fusion, Madrid, Spain] [Laboratory Nacional de Fusion, Madrid, Spain; Unamuno, R. [Laboratory Nacional de Fusion, Madrid, Spain] [Laboratory Nacional de Fusion, Madrid, Spain

    2011-01-01T23:59:59.000Z

    A new pellet injection system for the TJ-II stellarator has been developed/constructed as part of a collaboration between the Oak Ridge National Laboratory (ORNL) and the Centro de Investigaciones Energ ticas, Medioambientales y Tecnol gicas (CIEMAT). ORNL is providing most of the injector hardware and instrumentation, the pellet diagnostics, and the pellet transport tubes; CIEMAT is responsible for the injector stand/interface to the stellarator, cryogenic refrigerator, vacuum pumps/ballast volumes, gas manifolds, remote operations, plasma diagnostics, and data acquisition. The pellet injector design is an upgraded version of that used for the ORNL injector installed on the Madison Symmetric Torus (MST). It is a four-barrel system equipped with a cryogenic refrigerator for in situ hydrogen pellet formation and a combined mechanical punch/propellant valve system for pellet acceleration (speeds ~100 to 1000 m/s). On TJ-II, it will be used as an active diagnostic and for fueling. To accommodate the plasma experiments planned for TJ-II, pellet sizes significantly smaller than those typically used for the MST application are required. The system will initially be equipped with four different pellet sizes, with the gun barrel bores ranging between ~0.5 to 1.0 mm. The new system is almost complete and is described briefly here, highlighting the new features added since the original MST injector was constructed. Also, the future installation on TJ-II is reviewed.

  10. A Massive Stellar Burst Before the Supernova

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItemResearch >InternshipDepartment ofAugustDecember8threbuildAAAskedMonitoringNEUTRALA

  11. OPTICAL/NEAR-INFRARED SELECTION OF RED QUASI-STELLAR OBJECTS: EVIDENCE FOR STEEP EXTINCTION CURVES TOWARD GALACTIC CENTERS?

    SciTech Connect (OSTI)

    Fynbo, J. P. U.; Krogager, J.-K.; Vestergaard, M.; Geier, S. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Venemans, B. [Max-Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Noterdaeme, P. [CNRS-UPMC, UMR7095, Institut d'Astrophysique de Paris, 98bis Bd. Arago, F-75014 Paris (France); Moller, P. [European Southern Observatory, Karl-Schwarzschildstrasse 2, D-85748 Garching bei Muenchen (Germany); Ledoux, C. [European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago 19 (Chile)

    2013-01-15T23:59:59.000Z

    We present the results of a search for red QSOs using a selection based on optical imaging from the Sloan Digital Sky Survey (SDSS) and near-infrared imaging from UKIDSS. Our main goal with the selection is to search for QSOs reddened by foreground dusty absorber galaxies. For a sample of 58 candidates (including 20 objects fulfilling our selection criteria that already have spectra in the SDSS), 46 (79%) are confirmed to be QSOs. The QSOs are predominantly dust-reddened except for a handful at redshifts z {approx}> 3.5. However, the dust is most likely located in the QSO host galaxies (and for two, the reddening is primarily caused by Galactic dust) rather than in the intervening absorbers. More than half of the QSOs show evidence of associated absorption (BAL absorption). Four (7%) of the candidates turned out to be late-type stars, and another four (7%) are compact galaxies. We could not identify the remaining four objects. In terms of their optical spectra, these QSOs are similar to the QSOs selected in the FIRST-2MASS Red Quasar Survey except they are on average fainter, more distant, and only two are detected in the FIRST survey. As per the usual procedure, we estimate the amount of extinction using the SDSS QSO template reddened by Small-Magellanic-Cloud-(SMC) like dust. It is possible to get a good match to the observed (rest-frame ultraviolet) spectra, but it is not possible to match the observed near-IR photometry from UKIDSS for nearly all the reddened QSOs. The most likely reasons are that the SDSS QSO template is too red at optical wavelengths due to contaminating host galaxy light and because the assumed SMC extinction curve is too shallow. Three of the compact galaxies display old stellar populations with ages of several Gyr and masses of about 10{sup 10} M{sub Sun} (based on spectral energy distribution modeling). The inferred stellar densities in these galaxies exceed 10{sup 10} M{sub Sun} kpc{sup -2}, which is among the highest measured for early-type galaxies. Our survey has demonstrated that selection of QSOs based on near-IR photometry is an efficient way to select QSOs, including reddened QSOs, with only small contamination from late-type stars and compact galaxies. This will be useful with ongoing and future wide-field near-IR surveys such as the VISTA and EUCLID surveys.

  12. Sandia National Laboratories: Energy

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

    Laboratories on a new concentrated solar power (CSP) installation with thermal energy storage. The CSP storage project combines Areva's modular Compact Linear Fresnel...

  13. Residual zonal flows in tokamaks and stellarators at arbitrary wavelengths

    E-Print Network [OSTI]

    Monreal, P; Sánchez, E; Parra, F I; Bustos, A; Könies, A; Kleiber, R; Görler, T

    2015-01-01T23:59:59.000Z

    In the linear collisionless limit, a zonal potential perturbation in a toroidal plasma relaxes, in general, to a non-zero residual value. Expressions for the residual value in tokamak and stellarator geometries, and for arbitrary wavelengths, are derived. These expressions involve averages over the lowest order particle trajectories, that typically cannot be evaluated analytically. In this work, an efficient numerical method for the evaluation of such expressions is reported. It is shown that this method is faster than direct gyrokinetic simulations. Calculations of the residual value in stellarators are provided for much shorter wavelengths than previously available in the literature. Electrons must be treated kinetically in stellarators because, unlike in tokamaks, kinetic electrons modify the residual value even at long wavelengths. This effect, that had already been predicted theoretically, is confirmed by gyrokinetic simulations.

  14. Structural Reliability: Assessing the Condition and Reliability of Casing in Compacting Reservoirs

    E-Print Network [OSTI]

    Chantose, Prasongsit

    2012-02-14T23:59:59.000Z

    . Effective stress may exceed rock compressive strength, inducing compaction. Wells in compacting reservoirs risk high failure and deformation rates. This project introduces the concept of structural reliability to quantify casing failure risks in compacting...

  15. Structural Reliability: Assessing the Condition and Reliability of Casing in Compacting Reservoirs 

    E-Print Network [OSTI]

    Chantose, Prasongsit

    2012-02-14T23:59:59.000Z

    Casing has a higher risk of failure in a compacting reservoir than in a typical reservoir. Casing fails when reservoir compaction induces compression and shear stresses onto it. They compact as reservoir pressure depletes during production. High...

  16. Thermal and electrical conduction in the compaction direction of exfoliated graphite

    E-Print Network [OSTI]

    Chung, Deborah D.L.

    Thermal and electrical conduction in the compaction direction of exfoliated graphite in the compaction direction of graphite-flake-based exfoliated graphite have been decoupled. The compact Exfoliated graphite is elongated graphite particles obtained by the exfoliation (typically involving rapid

  17. Manifold corrections on spinning compact binaries

    SciTech Connect (OSTI)

    Zhong Shuangying; Wu Xin [Nanchang University, Nanchang 330031 (China)

    2010-05-15T23:59:59.000Z

    This paper deals mainly with a discussion of three new manifold correction methods and three existing ones, which can numerically preserve or correct all integrals in the conservative post-Newtonian Hamiltonian formulation of spinning compact binaries. Two of them are listed here. One is a new momentum-position scaling scheme for complete consistency of both the total energy and the magnitude of the total angular momentum, and the other is the Nacozy's approach with least-squares correction of the four integrals including the total energy and the total angular momentum vector. The post-Newtonian contributions, the spin effects, and the classification of orbits play an important role in the effectiveness of these six manifold corrections. They are all nearly equivalent to correct the integrals at the level of the machine epsilon for the pure Kepler problem. Once the third-order post-Newtonian contributions are added to the pure orbital part, three of these corrections have only minor effects on controlling the errors of these integrals. When the spin effects are also included, the effectiveness of the Nacozy's approach becomes further weakened, and even gets useless for the chaotic case. In all cases tested, the new momentum-position scaling scheme always shows the optimal performance. It requires a little but not much expensive additional computational cost when the spin effects exist and several time-saving techniques are used. As an interesting case, the efficiency of the correction to chaotic eccentric orbits is generally better than one to quasicircular regular orbits. Besides this, the corrected fast Lyapunov indicators and Lyapunov exponents of chaotic eccentric orbits are large as compared with the uncorrected counterparts. The amplification is a true expression of the original dynamical behavior. With the aid of both the manifold correction added to a certain low-order integration algorithm as a fast and high-precision device and the fast Lyapunov indicators of two nearby trajectories, phase space scans for chaos in the spinning compact binary system are given.

  18. Particle acceleration at supernova shocks in young stellar clusters

    E-Print Network [OSTI]

    Bykov, A M; Osipov, S M

    2011-01-01T23:59:59.000Z

    We briefly discuss models of energetic particle acceleration by supernova shock in active starforming regions at different stages of their evolution. Strong shocks may strongly amplify magnetic fields due to cosmic ray driven instabilities. We discuss the magnetic field amplification emphasizing the role of the long-wavelength instabilities. Supernova shock propagating in the vicinity of a powerful stellar wind in a young stellar cluster is argued to increase the maximal CR energies at a given evolution stage of supernova remnant (SNR) and can convert a sizeable fraction of the kinetic energy release into energetic particles.

  19. Star Formation and the Growth of Stellar Mass

    E-Print Network [OSTI]

    Eric F. Bell; Xian Zhong Zheng; Casey Papovich; Andrea Borch; Christian Wolf; Klaus Meisenheimer

    2007-04-23T23:59:59.000Z

    Recent observations have demonstrated a significant growth in the integrated stellar mass of the red sequence since z=1, dominated by a steadily increasing number of galaxies with stellar masses M* 3x10^10 M_sun blue galaxies would also be overproduced; i.e., most of the new stars formed in blue cloud galaxies are in the massive galaxies. We explore a simple truncation scenario in which these `extra' blue galaxies have their star formation suppressed by an unspecified mechanism or mechanisms; simple cessation of star formation in these extra blue galaxies is approximately sufficient to build up the red sequence at M*<10^11 M_sun.

  20. Process for forming coal compacts and product thereof

    DOE Patents [OSTI]

    Gunnink, Brett (Columbia, MO); Kanunar, Jayanth (Arlington, MA); Liang, Zhuoxiong (San Francisco, CA)

    2002-01-01T23:59:59.000Z

    A process for forming durable, mechanically strong compacts from coal particulates without use of a binder is disclosed. The process involves applying a compressive stress to a particulate feed comprising substantially water-saturated coal particles while the feed is heated to a final compaction temperature in excess of about 100.degree. C. The water present in the feed remains substantially in the liquid phase throughout the compact forming process. This is achieved by heating and compressing the particulate feed and cooling the formed compact at a pressure sufficient to prevent water present in the feed from boiling. The compacts produced by the process have a moisture content near their water saturation point. As a result, these compacts absorb little water and retain exceptional mechanical strength when immersed in high pressure water. The process can be used to form large, cylindrically-shaped compacts from coal particles (i.e., "coal logs") so that the coal can be transported in a hydraulic coal log pipeline.

  1. COMPACTION OF FIBERBOARD IN A 9975 SHIPPING PACKAGE

    SciTech Connect (OSTI)

    Stefek, T.; Daugherty, W.; Estochen, E.; Leduc, D.

    2011-05-11T23:59:59.000Z

    Compaction of lower layers in the fiberboard overpack has been observed in 9975 packages that contain elevated moisture. Lab testing has resulted in a better understanding of (1) the relationship between the fiberboard moisture level and compaction of the lower fiberboard assembly, and (2) the behavior of the fiberboard during transport. In laboratory tests, higher moisture content has been shown to correspond to higher total compaction of fiberboard material, greater rate of compaction, and continued compaction over a longer period of time. In addition, laboratory tests have shown that the application of a dynamic load results in higher fiberboard compaction. The test conditions and sample geometric/loading configurations were chosen to simulate the regulatory requirements for 9975 package input dynamic loading. Dynamic testing was conducted over a period of several months to acquire immediate and cumulative changes in geometric data for various moisture levels. Currently, one sample set has undergone a complete dynamic test regimen, while testing of another set is still in-progress. The dynamic input, data acquisition, test effects on sample dynamic parameters, and interim results from this test program will be summarized and compared to regulatory specifications for dynamic loading. This will provide a basis from which to evaluate the impact of moisture and fiberboard compaction on the safety basis for transportation (Safety Analysis Report for Packaging) and storage (facility Documented Safety Analysis) at the Savannah River Site (SRS).

  2. National Nuclear Security Administration | National Nuclear Security...

    National Nuclear Security Administration (NNSA)

    National Nuclear Security Administration | National Nuclear Security Administration Facebook Twitter Youtube Flickr RSS People Mission Managing the Stockpile Preventing...

  3. Office of National Infrastructure & Sustainability | National...

    National Nuclear Security Administration (NNSA)

    National Infrastructure & Sustainability | National Nuclear Security Administration Facebook Twitter Youtube Flickr RSS People Mission Managing the Stockpile Preventing...

  4. Pantex receives National Weather Service recognition | National...

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

    receives National Weather Service recognition | National Nuclear Security Administration Facebook Twitter Youtube Flickr RSS People Mission Managing the Stockpile Preventing...

  5. Study and Simulation of Remote Sensing System: COMPACT Airborne Spectral Sensor (COMPASS)

    E-Print Network [OSTI]

    Salvaggio, Carl

    1 Study and Simulation of Remote Sensing System: COMPACT Airborne Spectral Sensor (COMPASS) Paper............................................................................................ 5 COMPACT Airborne Spectral Sensor (COMPASS............................................................................................... 9 (FOUO) COMPASS Megacollect Data

  6. MACHO (MAssive Compact Halo Objects) Data

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    The primary aim of the MACHO Project is to test the hypothesis that a significant fraction of the dark matter in the halo of the Milky Way is made up of objects like brown dwarfs or planets: these objects have come to be known as MACHOs, for MAssive Compact Halo Objects. The signature of these objects is the occasional amplification of the light from extragalactic stars by the gravitational lens effect. The amplification can be large, but events are extremely rare: it is necessary to monitor photometrically several million stars for a period of years in order to obtain a useful detection rate. For this purpose MACHO has a two channel system that employs eight CCDs, mounted on the 50 inch telescope at Mt. Stromlo. The high data rate (several GBytes per night) is accommodated by custom electronics and on-line data reduction. The Project has taken more than 27,000 images with this system since June 1992. Analysis of a subset of these data has yielded databases containing light curves in two colors for 8 million stars in the LMC and 10 million in the bulge of the Milky Way. A search for microlensing has turned up four candidates toward the Large Magellanic Cloud and 45 toward the Galactic Bulge. The web page for data provides links to MACHO Project data portals and various specialized interfaces for viewing or searching the data. (Specialized Interface)

  7. Compact directed percolation with movable partial reflectors

    E-Print Network [OSTI]

    Ronald Dickman; Daniel ben-Avraham

    2002-07-08T23:59:59.000Z

    We study a version of compact directed percolation (CDP) in one dimension in which occupation of a site for the first time requires that a "mine" or antiparticle be eliminated. This process is analogous to the variant of directed percolation with a long-time memory, proposed by Grassberger, Chate and Rousseau [Phys. Rev. E 55, 2488 (1997)] in order to understand spreading at a critical point involving an infinite number of absorbing configurations. The problem is equivalent to that of a pair of random walkers in the presence of movable partial reflectors. The walkers, which are unbiased, start one lattice spacing apart, and annihilate on their first contact. Each time one of the walkers tries to visit a new site, it is reflected (with probability r) back to its previous position, while the reflector is simultaneously pushed one step away from the walker. Iteration of the discrete-time evolution equation for the probability distribution yields the survival probability S(t). We find that S(t) \\sim t^{-delta}, with delta varying continuously between 1/2 and 1.160 as the reflection probability varies between 0 and 1.

  8. The spheromak as a compact fusion reactor

    SciTech Connect (OSTI)

    Hagenson, R.L.; Krakowski, R.A.

    1987-03-01T23:59:59.000Z

    After summarizing the economic and utility-based rationale for compact, higher-power-density fusion reactors, the gun-sustained spheromak concept is explored as one of a number of poloidal-field-dominated confinement configurations that might improve the prospects for economically attractive and operationally simplified fusion power plants. Using a comprehensive physics/engineering/costing model for the spheromak, guided by realistic engineering constraints and physics extrapolation, a range of cost-optimized reactor design points is presented, and the sensitivity of cost to key physics, engineering, and operational variables is reported. The results presented herein provide the basis for conceptual engineering designs of key fusion-power-core (FPC) subsystems and more detailed plasma modeling of this promising, high mass-power-density concept, which stresses single-piece FPC maintenance, steady-state current drive through electrostatic magnetic helicity injection, a simplified co-axial electrode-divertor, and efficient resistive-coal equilibrium-field coils. The optimal FPC size and the cost estimates project a system that competes aggressively with the best offered by alternative energy sources while simplifying considerably the complexity that has generally been associated with most approaches to magnetic fusion energy.

  9. GUTs on Compact Type IIB Orientifolds

    SciTech Connect (OSTI)

    Blumenhagen, Ralph; /Munich, Max Planck Inst.; Braun, Volker; /Dublin Inst.; Grimm, Thomas W.; /Bonn U.; Weigand, Timo; /SLAC

    2008-12-01T23:59:59.000Z

    We systematically analyze globally consistent SU(5) GUT models on intersecting D7-branes in genuine Calabi-Yau orientifolds with O3- and O7-planes. Beyond the well-known tadpole and K-theory cancellation conditions there exist a number of additional subtle but quite restrictive constraints. For the realization of SU(5) GUTs with gauge symmetry breaking via U(1)Y flux we present two classes of suitable Calabi-Yau manifolds defined via del Pezzo transitions of the elliptically fibred hypersurface P{sub 1,1,1,6,9}[18] and of the Quintic P{sub 1,1,1,1,1}[5], respectively. To define an orientifold projection we classify all involutions on del Pezzo surfaces. We work out the model building prospects of these geometries and present five globally consistent string GUT models in detail, including a 3-generation SU(5) model with no exotics whatsoever. We also realize other phenomenological features such as the 10 10 5{sub H} Yukawa coupling and comment on the possibility of moduli stabilization, where we find an entire new set of so-called swiss-cheese type Calabi-Yau manifolds. It is expected that both the general constrained structure and the concrete models lift to F-theory vacua on compact Calabi-Yau fourfolds.

  10. Polymer quantum effects on compact stars models

    E-Print Network [OSTI]

    Guillermo Chacon-Acosta; Hector Hernandez-Hernandez

    2014-08-05T23:59:59.000Z

    In this work we study a completely degenerated fermion gas at zero temperature within a semiclassical approximation for the Hamiltonian arising in polymer quantum mechanics. Polymer quantum systems are quantum mechanical models quantized in a similar way as in loop quantum gravity that allow the study of the discreteness of space and other features of the loop quantization in a simplified way. We obtain the polymer modified thermodynamical properties noticing that the corresponding Fermi energy is exactly the same as if one directly polymerizes the momentum $p_F$. We also obtain the corresponding expansion of thermodynamical variables for small values of the polymer length scale $\\lambda$. With this results we study a simple model of a compact object where the gravitational collapse is supported by electron degeneracy pressure. We find polymer corrections to the mass of the star. When compared with typical measurements of the mass of white dwarfs we obtain a bound on the polymer length of $\\lambda^2\\lesssim 10^{-26}m^2$.

  11. Color superconducting quark matter in compact stars

    E-Print Network [OSTI]

    D. B. Blaschke; T. Klahn; F. Sandin

    2007-12-02T23:59:59.000Z

    Recent indications for high neutron star masses (M \\sim 2 M_sun) and large radii (R > 12 km) could rule out soft equations of state and have provoked a debate whether the occurence of quark matter in compact stars can be excluded as well. We show that modern quantum field theoretical approaches to quark matter including color superconductivity and a vector meanfield allow a microscopic description of hybrid stars which fulfill the new, strong constraints. For these objects color superconductivity turns out to be an essential ingredient for a successful description of the cooling phenomenology in accordance with recently developed tests. We discuss the energy release in the neutrino untrapping transition as a new aspect of the problem that hybrid stars masquerade themselves as neutron stars. Quark matter searches in future generations of low-temperature/high-density nucleus-nucleus collision experiments such as low-energy RHIC and CBM @ FAIR might face the same problem of an almost crossover behavior of the deconfinement transition. Therefore, diagnostic tools shall be derived from effects of color superconductivity.

  12. Compact noninvasive electron bunch-length monitor

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

    Roberts, B.; Mammei, R. R.; Poelker, M.; McCarter, J. L.

    2012-12-01T23:59:59.000Z

    A compact rf cavity was constructed that simultaneously resonates at many harmonic modes when excited by a repetitive bunched electron beam passing through its bore. The excitation of these modes provides a Fourier description of the temporal characteristics of the bunch train. The cavity was used to noninvasively characterize electron bunches produced from thin and thick GaAs photocathodes inside a DC high voltage photogun illuminated with 37 ps (full width half maximum, FWHM) laser pulses at repetition rates near 1500 MHz, at average beam current from 5 to 500????A , and at beam energy from 75 to 195 keV. The cavity bunch-length monitor could detect electron bunches as short as 57 ps (FWHM) when connected directly to a sampling oscilloscope, and could clearly distinguish bunches with varying degrees of space-charge induced growth and with different tail signatures. Efforts are under way to detect shorter bunches by designing cavities with increased bandwidth. This demonstration lends credibility to the idea that these cavities could also be used for other applications, including bunching and shaping, when driven with external rf.

  13. Iron-carbon compacts and process for making them

    DOE Patents [OSTI]

    Sheinberg, Haskell (Santa Fe, NM)

    2000-01-01T23:59:59.000Z

    The present invention includes iron-carbon compacts and a process for making them. The process includes preparing a slurry comprising iron powder, furfuryl alcohol, and a polymerization catalyst for initiating the polymerization of the furfuryl alcohol into a resin, and heating the slurry to convert the alcohol into the resin. The resulting mixture is pressed into a green body and heated to form the iron-carbon compact. The compact can be used as, or machined into, a magnetic flux concentrator for an induction heating apparatus.

  14. Star-formation properties of Hickson Compact Groups based on deep H{\\alpha} imaging

    E-Print Network [OSTI]

    Eigenthaler, Paul; Verdugo, Miguel; Ziegler, Bodo

    2015-01-01T23:59:59.000Z

    We present deep H{\\alpha} imaging of seven Hickson Compact Groups (HCGs) using the 4.1m Southern Astrophysics Research (SOAR) Telescope. The high spatial resolution of the observations allow us to study both the integrated star-formation properties of the main galaxies as well as the 2D distribution of star-forming knots in the faint tidal arms that form during interactions between the individual galaxies. We derive star-formation rates and stellar masses for group members and discuss their position relative to the main sequence of star-forming galaxies. Despite the existence of tidal features within the galaxy groups, we do not find any indication for enhanced star-formation in the selected sample of HCGs. We study azimuthally averaged H{\\alpha} profiles of the galaxy disks and compare them with the g' and r' surface-brightness profiles. We do not find any truncated galaxy disks but reveal that more massive galaxies show a higher light concentration in H{\\alpha} than less massive ones. We also see that galax...

  15. Repeated Bursts from Relativistic Scattering of Compact Objects in Galactic Nuclei

    E-Print Network [OSTI]

    Bence Kocsis; Janna Levin

    2012-07-09T23:59:59.000Z

    Galactic nuclei are densely populated by stellar mass compact objects such as black holes and neutron stars. Bound, highly eccentric binaries form as a result of gravitational wave (GW) losses during close flybys between these objects. We study the evolution of these systems using 2.5 and 3.5 order post-Newtonian equations of motion. The GW signal consists of many thousand repeated bursts (RB) for minutes to days (depending on the impact parameter and masses), followed by a powerful GW chirp and an eccentric merger. We show that a significant signal to noise ratio (SNR) accumulates already in the RB phase, corresponding to a detection limit around 200-300 Mpc and 300--600 Mpc for Advanced LIGO for an average orientation BH/NS or BH/BH binary, respectively. The theoretical errors introduced by the inaccuracy of the PN templates are typically much less severe for the RB phase than in the following eccentric merger. The GW signal in the RB phase is broadband; we show that encounters involving intermediate mass black holes are detectable in multiple frequency bands coincidentally using LIGO and LISA.

  16. A compact binary merger model for the short, hard GRB 050509b

    E-Print Network [OSTI]

    William H. Lee; Enrico Ramirez-Ruiz; Jonathan Granot

    2005-08-04T23:59:59.000Z

    The first X-ray afterglow for a short (~30 ms), hard gamma-ray burst was detected by Swift on 9 May 2005 (GRB 050509b). No optical or radio counterpart was identified in follow-up observations. The tentative association of the GRB with a nearby giant elliptical galaxy at redshift z=0.2248 would imply a total energy release E(gamma, isotropic) ~3 x 10**48 erg, and that the progenitor had traveled several tens of kpc from its point of origin, in agreement with expectations linking these events to the final merger of compact binaries driven by gravitational wave emission. We model the dynamical merger of such a system and the time-dependent evolution of the accretion tori thus created. The resulting energetics, variability, and expected durations are consistent with GRB 050509b originating from the tidal disruption of a neutron star by a stellar mass black hole, or of the merger of two neutron stars followed by prompt gravitational collapse of the massive remnant. We discuss how the available gamma-ray and X-ray data provide a probe for the nature of the relativistic ejecta and the surrounding medium.

  17. On the compact HII galaxy UM 408 as seen by GMOS-IFU: Physical conditions

    E-Print Network [OSTI]

    Lagos, Patricio; Munoz-Tunon, Casiana; Carrasco, Eleazar R; Cuisinier, Francois; Tenorio-Tagle, Guillermo

    2009-01-01T23:59:59.000Z

    We present Integral Field Unit GMOS-IFU data of the compact HII galaxy UM408, obtained at Gemini South telescope, in order to derive the spatial distribution of emission lines and line ratios, kinematics, plasma parameters, and oxygen abundances as well the integrated properties over an area of 3"x4".4(~750x1100 pc) located in the central part of the galaxy. The starburst in this area is resolved into two giant regions of ~375 and 250pc diameter, respectively. The ages of these two regions, estimated using Hb equivalent widths, suggest that they are coeval events of ~5Myr with stellar masses of ~10^4M_o. We have also used [OIII]/Hb and [SII]/Ha ratio maps to explore the excitation mechanisms in this galaxy. The Ha emission line was used to measure the radial velocity and velocity dispersion. We derived an integrated oxygen abundance of 12+log(O/H)=7.87 summing over all spaxels in our field of view. An average value of 12+log(O/H)=7.77 and a difference of D(O/H)=0.47 between the minimum and maximum values (7.5...

  18. Clusters of Extragalactic Ultra Compact HII Regions

    E-Print Network [OSTI]

    Kelsey E. Johnson; Chip Kobulnicky; Phil Massey; Peter Conti

    2001-07-10T23:59:59.000Z

    We report on the detection of optically thick free-free radio sources in the galaxies M33, NGC 253, and NGC 6946 using data in the literature. We interpret these sources as being young, embedded star birth regions, which are likely to be clusters of ultracompact HII regions. All 35 of the sources presented in this article have positive radio spectral indices alpha>0 suggesting an optically thick thermal bremsstrahlung emission arising in the HII region surrounding hot stars. Energy requirements indicate a range of a several to >500 O7V star equivalents powering each HII region. Assuming a Salpeter IMF, this corresponds to integrated stellar masses of 0.1--60,000 Msun. For roughly half of the sources in our sample, there is no obvious optical counterpart, giving further support for their deeply embedded nature. Their luminosities and radio spectral energy distributions are consistent with HII regions having electron densities from 1500 cm^-3 to 15000 cm^-3 and radii of 1 - 7 pc. We suggest that the less luminous of these sources are extragalactic ultracompact HII region complexes, those of intermediate luminosity are similar to W49 in the Galaxy, while the brightest will be counterparts to 30 Doradus. These objects constitute the lower mass range of extragalactic ``ultradense HII regions'' which we argue are the youngest stages of massive star cluster formation yet observed. This sample is beginning to fill in the continuum of objects between small associations of ultracompact HII regions and the massive extragalactic clusters that may evolve into globular clusters.

  19. ASTR 498N Spring 2014 Special Problems in Astronomy: Stellar Evolution

    E-Print Network [OSTI]

    Harrington, J. Patrick

    & The Virial Theorem Feb 4 Thermonuclear Fusion & Stellar Life Cycles 6 The H-R Diagram & Stellar Clusters 11; The Cooling of White Dwarfs Mar 4 *** First Mid-Term Exam *** 6 Thermonuclear Fusion in Stars Chapt 4 11

  20. Experimental investigation of opacity models for stellar interior, inertial fusion, and high energy density plasmasa...

    E-Print Network [OSTI]

    Experimental investigation of opacity models for stellar interior, inertial fusion, and high energy for calculating energy transport in plasmas. In particular, understanding stellar interiors, inertial fusion more energy and the backlight must be bright enough to overwhelm the plasma self

  1. Computer Models in Astronomy and Statistics Stellar Evolution

    E-Print Network [OSTI]

    van Dyk, David

    Computer Models in Astronomy and Statistics Stellar Evolution Calibration of X-ray Detectors Embedding Astronomical Computer Models into Complex Statistical Models David A. van Dyk Statistics Section Dyk Complex Analyses with Computer Models in Astronomy #12;Computer Models in Astronomy and Statistics

  2. Computer Models in Astronomy and Statistics Stellar Evolution

    E-Print Network [OSTI]

    van Dyk, David

    Computer Models in Astronomy and Statistics Stellar Evolution Calibration of X-ray Detectors Embedding Astronomical Computer Models into Complex Statistical Models David A. van Dyk Statistics Section, Imperial College London UCLA, February 2012 David A. van Dyk Complex Analyses with Computer Models

  3. Cirrus Microphysical Properties from Stellar Aureole Measurements, Phase I

    SciTech Connect (OSTI)

    DeVore, J.G.; Kristl, J.A.; Rappaport, S.A

    2012-04-20T23:59:59.000Z

    While knowledge of the impact of aerosols on climate change has improved significantly due to the routine, ground-based, sun photometer measurements of aerosols made at AERONET sites world-wide, the impact of cirrus clouds remains much less certain because they occur high in the atmosphere and are more difficult to measure. This report documents work performed on a Phase I SBIR project to retrieve microphysical properties of cirrus ice crystals from stellar aureole imagery. The Phase I work demonstrates that (1) we have clearly measured stellar aureole profiles; (2) we can follow the aureole profiles out to ~1/4 degree from stars (~1/2 degree from Jupiter); (3) the stellar aureoles from cirrus have very distinctive profiles, being flat out to a critical angle, followed by a steep power-law decline with a slope of ~-3; (4) the profiles are well modeled using exponential size distributions; and (5) the critical angle in the profiles is ~0.12 degrees, (6) indicating that the corresponding critical size ranges from ~150 to ~200 microns. The stage has been set for a Phase II project (1) to proceed to validating the use of stellar aureole measurements for retrieving cirrus particle size distributions using comparisons with optical property retrievals from other, ground-based instruments and (2) to develop an instrument for the routine, automatic measurement of thin cirrus microphysical properties.

  4. Modelling of Stellar Atmospheres IAU Symposium, Vol. xxx, xxxx

    E-Print Network [OSTI]

    Abstract. We discuss the dynamics in the outer atmospheres of AGB giants. 1. Motivation Hinkle et al. (1982 with an excitation temperature of about 800-1000 K and an almost zero velocity relative to the stellar systemic molecular envelope", should be common not only in Miras but in evolved red giants in general. 2. Project

  5. arXiv:astroph/0208546 Flare Heating in Stellar Coronae

    E-Print Network [OSTI]

    Guedel, Manuel

    J. Drake Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 vkashyap@astro.phys.ethz.ch ABSTRACT An open question in the #12;eld of solar and stellar astrophysics is the source of heating, but are more numerous. Previous analyses of ares in light-curves of active stars have shown that this index

  6. $?$-decay of key titanium isotopes in stellar environment

    E-Print Network [OSTI]

    Jameel-Un Nabi; Irgaziev Bakhadir

    2011-08-04T23:59:59.000Z

    Amongst iron regime nuclei, $\\beta$-decay rates on titanium isotopes are considered to be important during the late phases of evolution of massive stars. The key $\\beta$-decay isotopes during presupernova evolution were searched from available literature and a microscopic calculation of the decay rates were performed using the proton-neutron quasiparticle random phase approximation (pn-QRPA) theory. As per earlier simulation results electron capture and $\\beta$-decay on certain isotopes of titanium are considered to be important for the presupernova evolution of massive stars. Earlier the stellar electron capture rates and neutrino energy loss rates due to relevant titanium isotopes were presented. In this paper we finally present the $\\beta$-decay rates of key titanium isotopes in stellar environment. The results are also compared against previous calculations. The pn-QRPA $\\beta$-decay rates are bigger at high stellar temperatures and smaller at high stellar densities compared to the large scale shell model results. This study can prove useful for the core-collapse simulators.

  7. Grids of Stellar Models and Frequencies with CLES + LOSC

    E-Print Network [OSTI]

    J. Montalban; A. Miglio; A. Noels; R. Scuflaire

    2008-02-22T23:59:59.000Z

    We present a grid of stellar models, obtained with the CLES evolution code, following the specification of ESTA-Task1, and the corresponfing seismic properties, computed with the LOSC code. We provide a complete description of the corresponding files that will be available on the ESTA web-pages.

  8. Radiatively Driven Stellar Winds and Aspherical Mass Stan Owocki

    E-Print Network [OSTI]

    Owocki, Stanley P.

    (Castor, Abbott, and Klein 1975) model for radiative driving by scattering in a ensemble of lines from driving, fo­ cussing first on the standard CAK formalism for steady, line­driven stellar winds, University of Delaware, Newark, DE 19716 Abstract. The high luminosity of massive stars can drive substantial

  9. Radiatively Driven Stellar Winds and Aspherical Mass Stan Owocki

    E-Print Network [OSTI]

    Owocki, Stanley P.

    (Castor, Abbott, and Klein 1975) model for radiative driving by scattering in a ensemble of lines from driving, fo- cussing first on the standard CAK formalism for steady, line-driven stellar winds, University of Delaware, Newark, DE 19716 Abstract. The high luminosity of massive stars can drive substantial

  10. OPTIMIZATION OF STELLARATOR REACTOR PARAMETERS J. F. Lyon1

    E-Print Network [OSTI]

    OPTIMIZATION OF STELLARATOR REACTOR PARAMETERS J. F. Lyon1 , L.P. Ku2 , P. Garabedian3 , L. El-average) approach for optimizing the main reactor parameters allows study of the relationship between global developed to optimize the main reactor parameters (, the average magnetic field on axis , etc

  11. ISO impact on stellar models and vice versa

    E-Print Network [OSTI]

    L. Decin; C. Waelkens; K. Eriksson; B. Gustafsson; B. Plez; A. J. Sauval; W. Van Assche; B. Vandenbussche

    2000-08-23T23:59:59.000Z

    We present a detailed spectroscopic study of a sample of bright, mostly cool, stars observed with the Short-Wavelength Spectrometer (SWS) on board the Infrared Space Observatory (ISO), which enables the accurate determination of the stellar parameters of the cool giants, but also serves as a critical review of the ISO-SWS calibration.

  12. Preparation of bulk superhard B-C-N nanocomposite compact

    DOE Patents [OSTI]

    Zhao, Yusheng (Los Alamos, NM); He, Duanwei (Sichuan, CN)

    2011-05-10T23:59:59.000Z

    Bulk, superhard, B--C--N nanocomposite compacts were prepared by ball milling a mixture of graphite and hexagonal boron nitride, encapsulating the ball-milled mixture at a pressure in a range of from about 15 GPa to about 25 GPa, and sintering the pressurized encapsulated ball-milled mixture at a temperature in a range of from about 1800-2500 K. The product bulk, superhard, nanocomposite compacts were well sintered compacts with nanocrystalline grains of at least one high-pressure phase of B--C--N surrounded by amorphous diamond-like carbon grain boundaries. The bulk compacts had a measured Vicker's hardness in a range of from about 41 GPa to about 68 GPa.

  13. Compact Data Structures with Fast Queries Daniel K. Blandford

    E-Print Network [OSTI]

    .5 Decoding Multiple Gamma Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.6 Rank of Computer Science Carnegie Mellon University Pittsburgh, PA 15213 Thesis Committee: Guy E. Blelloch, chair fast queries (and updates) to the data. This thesis describes compact representations of several types

  14. aeropropulsion compact lightweight: Topics by E-print Network

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

    24 25 Next Page Last Page Topic Index 1 Design of a compact, lightweight, and low-cost solar concentrator MIT - DSpace Summary: The objective of this mechanical design project was...

  15. Compact hot-nozzle fourier-transform microwave spectormeter

    E-Print Network [OSTI]

    Harmony, Marlin D.; Ratzlaff, Kenneth L.; Angst, D. M.; Beren, K. A.

    1995-11-01T23:59:59.000Z

    A newly constructed pulsed nozzle, Fourier-transform microwave spectrometer utilizes a Fabry-Perot cavity consisting of spherical resonators having diameters of only 10 cm. Tests of this very compact-cavity system show ...

  16. Development, Test and Demonstration of a Cost-Effective, Compact...

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

    and Peer Evaluation ape012taylor2011o.pdf More Documents & Publications Development, Test and Demonstration of a Cost-Effective, Compact, Light-Weight, and Scalable High...

  17. A Plastic-Core Compact Heat Exchanger for Energy Conservation

    E-Print Network [OSTI]

    Lazaridis, A.; Rafailidis, E.

    This paper describes a compact, single-pass, cross-flow type, gas-to-gas heat exchanger with a polyolefin (polyethylene or polypropylene) core whose seams are welded through a proprietary process. It is constructed of several extruded polyolefin...

  18. Classification of Certain Compact Riemannian Manifolds with Harmonic Curvature a...

    E-Print Network [OSTI]

    Derdzinski, Andrzej

    Classification of Certain Compact Riemannian Manifolds with Harmonic Curvature a... Derdzinski and University Library provides access to digitized documents strictly for noncommercial educational, research) requires prior written permission from the Goettingen State- and University Library. Each copy of any part

  19. A Plastic-Core Compact Heat Exchanger for Energy Conservation 

    E-Print Network [OSTI]

    Lazaridis, A.; Rafailidis, E.

    1995-01-01T23:59:59.000Z

    This paper describes a compact, single-pass, cross-flow type, gas-to-gas heat exchanger with a polyolefin (polyethylene or polypropylene) core whose seams are welded through a proprietary process. It is constructed of several extruded polyolefin...

  20. CTI in NSTX, Proposal for Compact Toroid Injection in NSTX

    SciTech Connect (OSTI)

    R. Raman

    2008-11-04T23:59:59.000Z

    This is the final Report summarizing the activities of the proposal to invetigate the potential of deep fueling a spherical torus or tokamak using high velocity injection of compact toroids.

  1. Compact, Isolated High-Velocity Clouds

    E-Print Network [OSTI]

    W. B. Burton; R. Braun; V. de Heij

    2002-06-20T23:59:59.000Z

    We consider here the class of compact, isolated, high-velocity HI clouds, CHVCs, which are sharply bounded in angular extent down to a limiting column density of 1.5x10^18 cm^-2. We describe our automated search algorithm and it's application to the LDS north of dec= -28 deg. and the HIPASS data south of dec=0, resulting in an all--sky catalog numbering 246 CHVCs. We argue that these objects are more likely to represent a single phenomenon in a similar evolutionary state than would a sample which included any of the major HVC complexes. Five principal observables are defined for the CHVC population: (1) the spatial deployment of the objects on the sky, (2) the kinematic distribution, (3) the number distribution of observed HI column densities, (4) the number distribution of angular sizes, and (5) the number distribution of line widths. We show that the spatial and kinematic deployments of the ensemble of CHVCs contain various clues regarding their characteristic distance. These clues are not compatible with a location of the ensemble within the Galaxy proper. The deployments resemble in several regards those of the Local Group galaxies. We describe a model testing the hypothesis that the CHVCs are a Local Group population. The agreement of the model with the data is judged by extracting the observables from simulations, in a manner consistent with the sensitivities of the observations and explicitly taking account of Galactic obscuration. We show that models in which the CHVCs are the HI counterparts of dark-matter halos evolving in the Local Group potential provide a good match to the observables, if account is taken of tidal and ram--pressure disruption, the consequences of obscuration due to Galactic HI and of differing sensitivities and selection effects pertaining to the surveys.

  2. Stellar models with the ML2 theory of convection

    E-Print Network [OSTI]

    M. Salaris; S. Cassisi

    2008-07-05T23:59:59.000Z

    The mixing length theory (MLT) used to compute the temperature gradient in superadiabatic layers of stellar (interior and atmosphere) models contains in its standard form 4 free parameters. Three parameters are fixed a priori (and define what we denote as the MLT 'flavour') whereas one (the so-called mixing length) is calibrated by reproducing observational constraints. The 'classical' B\\"ohm-Vitense flavour is used in all modern MLT-based stellar model computations and, despite its crude approximations, the resulting $T_{eff}$ scale appears -- perhaps surprisingly -- remarkably realistic, once the mixing length parameter is calibrated with a solar model. Model atmosphere computations employ parameter choices different from what is used in stellar interior modelling, raising the question of whether a single MLT flavour and mixing length value can be used to compute interiors and atmospheres of stars of all types. As a first step towards addressing this issue, we study whether the MLT flavour (the so-called ML2) and mixing length choice that have been proven adequate to model white dwarf atmospheres, is able to provide, when used in stellar models, results at least comparable to the use of the 'classical' B\\"ohm-Vitense flavour. We have computed solar models and evolutionary tracks for both low- and intermediate-mass Population I and II stars, adopting both solar calibrated B\\"ohm-Vitense and ML2 flavours of the MLT in our stellar evolution code, and state-of-the-art input physics. The two sets of models provide consistent results, with only minor differences. Both calibrations reproduce also the $T_{eff}$ of red giants in a sample of Galactic globular clusters.

  3. Engineering properties of miniature cement - fly ash compacts prepared by high pressure compaction 

    E-Print Network [OSTI]

    Bormann, Jeffrey Ray

    1985-01-01T23:59:59.000Z

    ENGINEERING PROPERTIES OF MINIATURE CEMENT - FLY ASH COMPACTS PREPARED BY HIGH PRESSURE COMPACTION E NGIRPR OT SFMMAFU AEU C-ALEYY HDOBPvvIi va vGI ge(iD(vI oannItI au NId(R E)L xrP1IeRPvT 9(evP(n uDnuPnnBIrv au vGI eI0DPeIBIrvR uae vGI i...?H?? NId(R E)L xrP1IeRPvT oG(PeB(r au Ei1PRaeT oaBBPvvII? ?e? ??C? ?IiOIvvIe oDeeIrv 9e(8vP8IR (ri vGIaeT 8aruaeB va vGI 8ar8I9v vG(v uae R9I8P(nP?Ii DRIR ( 9aevn(ri 8IBIrv 8ar8eIvI B(vIeP(n ?PvG RveIrtvG (99ea(8GPrt ?????? 9RP B(T OI 9eaiD8Ii OT eIiD8...

  4. Ship response using a compact wave spectrum model

    E-Print Network [OSTI]

    Linn, Larry Donald

    1985-01-01T23:59:59.000Z

    statistical technique, known as principal component analysis, is used to compact large data bases of theoretical and real spectral information. Statistical properties of the various data bases are examined in their original and compacted forms. Sensitivity.... The available spectrum models fall into two basic categories. Formulas which use the first, or "classic, " approach use wind speed as the independent variable to define the spectrum. The Pierson-Noskowitz Spectrum is an example of this type...

  5. Stuck-at-fault test set compaction

    E-Print Network [OSTI]

    Vanfickell, Jason Michael

    2013-02-22T23:59:59.000Z

    of sltcp g(0. 5-ones~robo~, ~) Exc Bal, = 0. 25 ? of sites Figure 1. Formula for computation of the excitation balance Excitation balance is a metric computed for every detectable fault in the entire circuit. It is intended to provide a measure... Sigma ~ National Society of Collegiate Scholars Activities: ~ Texas A&M University Institute of Electrical and Electronic Engineers IT/Technology Chair and Webmaster, Fall 2003 ? Spring 2004 ~ Texas A&M University Student Engineers' Council...

  6. Compact Absorption Chiller - Energy Innovation Portal

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville Power Administration would like submit the followingth Lomonosov1 COMMUNITYGeothermal Geothermal

  7. A Stellar Spectral Flux Library, 1150|25000 A A. J. Pickles

    E-Print Network [OSTI]

    Pickles, Andrew J.

    strengths were used to check that each input component has closely similar stellar type. The library has of a smooth energy distribution formed from standard colors for the relevant types. The library is designed inconsistencies in libraries which group spectra by stellar type. Theoretical stellar spectra are often preferred

  8. National Competitiveness

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItemResearch > The EnergyCenterDioxide CaptureSee theOilNRELTechnologies

  9. National Security

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItemResearch > The EnergyCenterDioxide CaptureSeeNUCLEAR SCIENCE WEEKSecurity LLNL's

  10. NATIONAL LABORATORY

    Office of Scientific and Technical Information (OSTI)

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItem Not Found Item Not Found TheHot electron dynamicsAspen Aerogels,AluminumApproved for

  11. NATIONAL LABORATORY

    Office of Environmental Management (EM)

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33Frequently Asked QuestionsDepartment of Energy 3Services and LowersSafety andNASAand North

  12. COMPACT HEAT EXCHANGERS FOR CONDENSATION APPLICATIONS: YESTERDAY,

    Office of Scientific and Technical Information (OSTI)

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItem Not Found Item Not Found The itemAIR57451 Clean Energy Technologies A! CJ M H

  13. Compact Potentiometric NOx Sensor | Department of Energy

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

    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: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: Theof"Wave the WhiteNational| DepartmentCommunities WHAT:Commute1 DOE

  14. Compact Potentiometric NOx Sensor | Department of Energy

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

    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: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: Theof"Wave the WhiteNational| DepartmentCommunities WHAT:Commute1 DOE10 DOE

  15. Compact Potentiometric NOx Sensor | Department of Energy

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

    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: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: Theof"Wave the WhiteNational| DepartmentCommunities WHAT:Commute1 DOE10 DOE09

  16. Berkeley Lab Compact Accelerator Sets World Record

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625govInstrumentstdmadapInactiveVisiting the TWP TWPAlumniComplex historianBenefits of BESBerkeley Lab Particle

  17. National System Templates: Building Sustainable National Inventory...

    Open Energy Info (EERE)

    Templates: Building Sustainable National Inventory Management Systems Jump to: navigation, search Tool Summary LAUNCH TOOL Name: National System Templates: Building Sustainable...

  18. The Milky Way's stellar halo - lumpy or triaxial?

    E-Print Network [OSTI]

    Heidi Jo Newberg; Brian Yanny

    2005-07-28T23:59:59.000Z

    We present minimum chi-squared fits of power law and Hernquist density profiles to F-turnoff stars in eight 2.5 deg wide stripes of SDSS data: five in the North Galactic Cap and three in the South Galactic cap. Portions of the stellar Galactic halo that are known to contain large streams of tidal debris or other lumpy structure, or that may include significant contamination from the thick disk, are avoided. The data strongly favor a model that is not symmetric about the Galaxy's axis of rotation. If included as a free parameter, the best fit to the center of the spheroid is surprisingly approx 3 kpc from the Galactic center in the direction of the Sun's motion. The model fits favor a low value of the density of halo stars at the solar position. The alternative to a non-axisymmetric stellar distribution is that our fits are contaminated by previously unidentified lumpy substructure.

  19. Absolute Lineshifts - A new diagnostic for stellar hydrodynamics

    E-Print Network [OSTI]

    Dainis Dravins

    2003-02-28T23:59:59.000Z

    For hydrodynamic model atmospheres, absolute lineshifts are becoming an observable diagnostic tool beyond the classical ones of line-strength, -width, -shape, and -asymmetry. This is the wavelength displacement of different types of spectral lines away from the positions naively expected from the Doppler shift caused by stellar radial motion. Caused mainly by correlated velocity and brightness patterns in granular convection, such absolute lineshifts could in the past be studied only for the Sun (since the relative Sun-Earth motion, and the ensuing Doppler shift is known). For other stars, this is now becoming possible thanks to three separate developments: (a) Astrometric determination of stellar radial motion; (b) High-resolution spectrometers with accurate wavelength calibration, and (c) Accurate laboratory wavelengths for several atomic species. Absolute lineshifts offer a tool to segregate various 2- and 3-dimensional models, and to identify non-LTE effects in line formation.

  20. Absolute Lineshifts - A new diagnostic for stellar hydrodynamics

    E-Print Network [OSTI]

    Dravins, D

    2003-01-01T23:59:59.000Z

    For hydrodynamic model atmospheres, absolute lineshifts are becoming an observable diagnostic tool beyond the classical ones of line-strength, -width, -shape, and -asymmetry. This is the wavelength displacement of different types of spectral lines away from the positions naively expected from the Doppler shift caused by stellar radial motion. Caused mainly by correlated velocity and brightness patterns in granular convection, such absolute lineshifts could in the past be studied only for the Sun (since the relative Sun-Earth motion, and the ensuing Doppler shift is known). For other stars, this is now becoming possible thanks to three separate developments: (a) Astrometric determination of stellar radial motion; (b) High-resolution spectrometers with accurate wavelength calibration, and (c) Accurate laboratory wavelengths for several atomic species. Absolute lineshifts offer a tool to segregate various 2- and 3-dimensional models, and to identify non-LTE effects in line formation.

  1. Diamagnetic pumping near the base of a stellar convection zone

    E-Print Network [OSTI]

    L. L. Kitchatinov; G. Rüdiger

    2008-02-18T23:59:59.000Z

    The property of inhomogeneous turbulence in conducting fluids to expel large-scale magnetic fields in the direction of decreasing turbulence intensity is shown as important for the magnetic field dynamics near the base of a stellar convection zone. The downward diamagnetic pumping confines a fossil internal magnetic field in the radiative core so that the field geometry is appropriate for formation of the solar tachocline. For the stars of solar age, the diamagnetic confinement is efficient only if the ratio of turbulent magnetic diffusivity of the convection zone to the (microscopic or turbulent) diffusivity of the radiative interiour is larger than 10^5. Confinement in younger stars require still larger diffusivity ratio. The observation of persistent magnetic structures on young solar-type stars can thus provide evidences for the nonexistence of tachoclines in stellar interiors and on the level of turbulence in radiative cores.

  2. Paper No. PIIB.6 THE 13TH INTERNATIONAL STELLARATOR WORKSHOP

    E-Print Network [OSTI]

    Redi, Martha H.

    Laboratory, The Australian National University, Canberra, ACT 0200, Australia (4) Centre de Recherche en

  3. Facilities | Argonne National Laboratory

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

    Some of the nation's most powerful and sophisticated facilities for energy research Argonne National Laboratory is home to some of the nation's most powerful and sophisticated...

  4. DEEP HUBBLE SPACE TELESCOPE IMAGING IN NGC 6397: STELLAR DYNAMICS

    SciTech Connect (OSTI)

    Heyl, J. S.; Richer, H.; Woodley, K. A. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada); Anderson, J.; Dotter, A.; Kalirai, J. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Fahlman, G.; Stetson, P. [Herzberg Institute for Astrophysics, National Research Council, Victoria, BC (Canada); Hurley, J. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, VIC 3122 (Australia); Rich, R. M. [Division of Astronomy, University of California, Los Angeles, CA 90095-1562 (United States); Shara, M.; Zurek, D. [American Museum of Natural History, New York, NY 10024-5192 (United States)

    2012-12-10T23:59:59.000Z

    Multi-epoch observations with the Advanced Camera for Surveys on the Hubble Space Telescope provide a unique and comprehensive probe of stellar dynamics within NGC 6397. We are able to confront analytic models of the globular cluster with the observed stellar proper motions. The measured proper motions probe well along the main sequence from 0.8 to below 0.1 M{sub Sun} as well as white dwarfs younger than 1 Gyr. The observed field lies just beyond the half-light radius where standard models of globular cluster dynamics (e.g., based on a lowered Maxwellian phase-space distribution) make very robust predictions for the stellar proper motions as a function of mass. The observed proper motions show no evidence for anisotropy in the velocity distribution; furthermore, the observations agree in detail with a straightforward model of the stellar distribution function. We do not find any evidence that the young white dwarfs have received a natal kick in contradiction with earlier results. Using the observed proper motions of the main-sequence stars, we obtain a kinematic estimate of the distance to NGC 6397 of 2.2{sup +0.5}{sub -0.7} kpc and a mass of the cluster of 1.1 {+-} 0.1 Multiplication-Sign 10{sup 5} M{sub Sun} at the photometric distance of 2.53 kpc. One of the main-sequence stars appears to travel on a trajectory that will escape the cluster, yielding an estimate of the evaporation timescale, over which the number of stars in the cluster decreases by a factor of e, of about 3 Gyr. The proper motions of the youngest white dwarfs appear to resemble those of the most massive main-sequence stars, providing the first direct constraint on the relaxation time of the stars in a globular cluster of greater than or about 0.7 Gyr.

  5. Thermal distributions in stellar plasmas, nuclear reactions and solar neutrinos

    E-Print Network [OSTI]

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

    1998-11-24T23:59:59.000Z

    The physics of nuclear reactions in stellar plasma is reviewed with special emphasis on the importance of the velocity distribution of ions. Then the properties (density and temperature) of the weak-coupled solar plasma are analysed, showing that the ion velocities should deviate from the Maxwellian distribution and could be better described by a weakly-nonexstensive (|q-1|solar neutrino fluxes, and on the pp neutrino energy spectrum, and analyse the consequences for the solar neutrino problem.

  6. Progress in understanding and exploiting stellar oscillation spectra

    E-Print Network [OSTI]

    W. A. Dziembowski

    2005-09-15T23:59:59.000Z

    Rich oscillation spectra of dwarf-like pulsators contain a wealth of information about the object interiors and, in particular, about macroscopic transport processes, which is the most difficult aspect of stellar physics. Examples of extracting such information from data on solar-like and opacity driven pulsators are given. Problems in understanding new oscillation spectra are discussed. Importance of employing various data on excited mode is emphasized.

  7. The instantaneous radial growth rate of stellar discs

    E-Print Network [OSTI]

    Pezzulli, Gabriele; Boissier, Samuel; Muñoz-Mateos, Juan Carlos

    2015-01-01T23:59:59.000Z

    We present a new and simple method to measure the instantaneous mass and radial growth rates of the stellar discs of spiral galaxies, based on their star formation rate surface density (SFRD) profiles. Under the hypothesis that discs are exponential with time-varying scalelengths, we derive a universal theoretical profile for the SFRD, with a linear dependence on two parameters: the specific mass growth rate $\

  8. Ionising stellar populations in circumnuclear star forming regions

    E-Print Network [OSTI]

    Enrique Perez-Montero; Angeles I. Diaz; Marcelo Castellanos

    2004-11-10T23:59:59.000Z

    We present a study of the stellar populations and gas physical conditions in Circumnuclear Star Forming Regions (CNSFRs) based on spectrophotometric data, including the 7000 angstroms to 1 micron spectral range, which is of great interest to the whole diagnostic of the ionized gas. The properties of CNSFRs as a class are inferred from a comparison with those of other star forming emission-line objects: low excitation disc HII regions and HII galaxies.

  9. The stellar wind velocity field of HD 77581

    E-Print Network [OSTI]

    Manousakis, A

    2015-01-01T23:59:59.000Z

    The early acceleration of stellar winds in massive stars is poorly constrained. The scattering of hard X-ray photons emitted by the pulsar in the high-mass X-ray binary Vela X-1 can be used to probe the stellar wind velocity and density profile close to the surface of its supergiant companion HD 77581. We built a high signal-to-noise and high resolution hard X-ray lightcurve of Vela X-1 measured by Swift/BAT over 300 orbital periods of the system and compared it with the predictions of a grid of hydrodynamic simulations. We obtain a very good agreement between observations and simulations for a narrow set of parameters, implying that the wind velocity close to the stellar surface is twice larger than usually assumed with the standard beta law. Locally a velocity gradient of $\\beta\\sim0.5$ is favoured. Even if still incomplete, hydrodynamic simulations are successfully reproducing several observational properties of Vela X-1.

  10. The LAMOST Stellar Parameter Pipeline at Peking University --- LSP3

    E-Print Network [OSTI]

    Xiang, Maosheng; Yuan, Haibo; Huang, Yang; Huo, Zhiying; Zhang, Huawei; Chen, Bingqiu; Zhang, Huihua; Sun, Ningchen; Wang, Chun; Zhao, Yongheng; Shi, Jianrong; Luo, Ali; Li, Guoping; Wu, Yue; Bai, Zongrui; Zhang, Yong; Hou, Yonghui; Yuan, Hailong; Li, Guangwei

    2014-01-01T23:59:59.000Z

    We introduce the LAMOST Stellar Parameter Pipeline at Peking University --- LSP3, developed and implemented for the determinations of radial velocity $V_{\\rm r}$ and stellar atmospheric parameters (effective temperature $T_{\\rm eff}$, surface gravity log\\,$g$, metallicity [Fe/H]) for the LAMOST Spectroscopic Survey of the Galactic Anti-center (LSS-GAC). We describe the algorithms of LSP3 and examine the accuracy of parameters yielded by it. The precision and accuracy of parameters yielded are investigated by comparing results of multi-epoch observations and of candidate members of open and globular clusters, with photometric calibration, as well as with independent determinations available from a number of external databases, including the PASTEL archive, the APOGEE, SDSS and RAVE surveys, as well as those released in the LAMOST DR1. The uncertainties of LSP3 parameters are characterized and quantified as a function of the spectral signal-to-noise ratio (SNR) and stellar atmospheric parameters. We conclude th...

  11. Stellar coronal magnetic fields and star-planet interaction

    E-Print Network [OSTI]

    Lanza, A F

    2009-01-01T23:59:59.000Z

    Evidence of magnetic interaction between late-type stars and close-in giant planets is provided by the observations of stellar hot spots rotating synchronously with the planets and showing an enhancement of chromospheric and X-ray fluxes. We investigate star-planet interaction in the framework of a magnetic field model of a stellar corona, considering the interaction between the coronal field and that of a planetary magnetosphere moving through the corona. The energy budget of the star-planet interaction is discussed assuming that the planet may trigger a release of the energy of the coronal field by decreasing its relative helicity. The observed intermittent character of the star-planet interaction is explained by a topological change of the stellar coronal field, induced by a variation of its relative helicity. The model predicts the formation of many prominence-like structures in the case of highly active stars owing to the accumulation of matter evaporated from the planet inside an azimuthal flux rope in ...

  12. Masses of Stellar Black Holes and Testing Theories of Gravitation

    E-Print Network [OSTI]

    K. A. Postnov; A. M. Cherepashchuk

    2004-01-22T23:59:59.000Z

    We analyze the mass distribution of stellar black holes derived from the light and radial velocity curves of optical stars in close binary systems using dynamical methods. The systematic errors inherent in this approach are discussed. These are associated primarily with uncertainties in models for the contribution from gaseous structures to the optical brightness of the systems under consideration. The mass distribution is nearly flat in the range 4-15M_sun. This is compared with the mass distribution for black holes in massive close binaries, which can be manifest as ultraluminous X-ray sources (L_x > 10^39 erg/s) observed in other galaxies. If the X-ray luminosities of these objects correspond to the Eddington limit, the black-hole mass distribution should be described by a power law, which is incompatible with the flat shape derived dynamically from observations of close binaries in our Galaxy. One possible explanation of this discrepancy is the rapid evaporation of stellar-mass black holes predicted in recent multi-dimensional models of gravity. This hypothesis can be verifed by measuring the stellar black-hole mass spectrum or finding isolated or binary black holes with masses below 3M_sun.

  13. Modern yields per stellar generation: the effect of the IMF

    E-Print Network [OSTI]

    Vincenzo, Fiorenzo; Belfiore, Francesco; Maiolino, Roberto

    2015-01-01T23:59:59.000Z

    Gaseous and stellar metallicities in galaxies are nowadays routinely used to constrain the evolutionary processes in galaxies. This requires the knowledge of the average yield per stellar generation, $y_{\\text{Z}}$, i.e. the quantity of metals that a stellar population releases into the interstellar medium (ISM), which is generally assumed to be a fixed fiducial value. Deviations of the observed metallicity from the expected value of $y_{\\text{Z}}$ are used to quantify the effect of outflows or inflows of gas, or even as evidence for biased metallicity calibrations or inaccurate metallicity diagnostics. Here we show that $\\rm y_{\\text{Z}}$ depends significantly on the Initial Mass Function (IMF), varying by up to a factor larger than three, for the range of IMFs typically adopted in various studies. This, along with the variation of the gas mass fraction restored into the ISM by supernovae ($R$, which also depends on the IMF), may yield to deceiving results, if not properly taken into account. In particular, ...

  14. Evolution of stellar disk truncations since z=1

    E-Print Network [OSTI]

    Ignacio Trujillo; Ruyman Azzollini; Judit Bakos; John Beckman; Michael Pohlen

    2008-07-26T23:59:59.000Z

    We present our recent results on the cosmic evolution of the outskirst of disk galaxies. In particular we focus on disk-like galaxies with stellar disk truncations. Using UDF, GOODS and SDSS data we show how the position of the break (i.e. a direct estimator of the size of the stellar disk) evolves with time since z~1. Our findings agree with an evolution on the radial position of the break by a factor of 1.3+-0.1 in the last 8 Gyr for galaxies with similar stellar masses. We also present radial color gradients and how they evolve with time. At all redshift we find a radial inside-out bluing reaching a minimum at the position of the break radius, this minimum is followed by a reddening outwards. Our results constraint several galaxy disk formation models and favour a scenario where stars are formed inside the break radius and are relocated in the outskirts of galaxies through secular processes.

  15. Compact Reversed-Field Pinch Reactors (CRFPR): preliminary engineering considerations

    SciTech Connect (OSTI)

    Hagenson, R.L.; Krakowski, R.A.; Bathke, C.G.; Miller, R.L.; Embrechts, M.J.; Schnurr, N.M.; Battat, M.E.; LaBauve, R.J.; Davidson, J.W.

    1984-08-01T23:59:59.000Z

    The unique confinement physics of the Reversed-Field Pinch (RFP) projects to a compact, high-power-density fusion reactor that promises a significant reduction in the cost of electricity. The compact reactor also promises a factor-of-two reduction in the fraction of total cost devoted to the reactor plant equipment (i.e., fusion power core (FPC) plus support systems). In addition to operational and developmental benefits, these physically smaller systems can operate economically over a range of total power output. After giving an extended background and rationale for the compact fusion approaches, key FPC subsystems for the Compact RFP Reactor (CRFPR) are developed, designed, and integrated for a minimum-cost, 1000-MWe(net) system. Both the problems and promise of the compact, high-power-density fusion reactor are quantitatively evaluated on the basis of this conceptual design. The material presented in this report both forms a framework for a broader, more expanded conceptual design as well as suggests directions and emphases for related research and development.

  16. The DPOSS II compact group survey: first spectroscopically confirmed candidates

    E-Print Network [OSTI]

    Pompei, E; Iovino, A

    2006-01-01T23:59:59.000Z

    This paper presents the results of a pilot redshift survey of 18 candidate compact groups from the distant DPOSS survey that extends the available surveys of compact groups of galaxies to z ~0.2 in redshift, mainly Hickson Compact Groups and Southern Compact Groups. The goal of our survey was to confirm group membership via redshift information and to measure the characteristic parameters of a representative, albeit small, sample of DPOSS survey groups. Of the 18 candidates observed, seven are found to be indeed isolated compact groups, i.e. groups with 3 or more concordant members and with no neighbouring known cluster, while 7 are chance projection configurations on the sky. Three remaining candidates, despite having 3 or more concordant member galaxies, are located in the neighbourhood of known clusters, while another candidate turned out to be a dense sub-condensation within Abell 0952. The median redshift of our 7 confirmed groups is z ~0.12, to be compared with a median redshift of 0.03 for the local sa...

  17. Compact Radio Sources and Jet-driven AGN Feedback in the Early Universe: Constraints from Integral-Field Spectroscopy

    SciTech Connect (OSTI)

    Nesvadba, N H; Lehnert, M D; De Breuck, C; Gilbert, A; van Breugel, W

    2007-07-05T23:59:59.000Z

    To investigate the impact of radio jets during the formation epoch of their massive host galaxies, we present an analysis of two massive, log M{sub stellar}/M{sub {circle_dot}} {approx} 10.6 and 11.3, compact radio galaxies at z = 3.5, TNJ0205+2242 and TNJ0121+1320. Their small radio sizes (R {le} 10 kpc) are most likely a sign of youth. In particular, we compare their radio properties and gas dynamics with those in well extended radio galaxies at high redshift, which show strong evidence for powerful, jet-driven outflows of significant gas masses (M {approx} 10{sup 9-10} M{sub {circle_dot}}). Our analysis combines rest-frame optical integral-field spectroscopy obtained with SINFONI on the VLT with existing radio imaging, CO(4-3) emission line spectra, and rest-frame UV longslit spectroscopy. [OIII]{lambda}5007 line emission is compact in both galaxies and lies within the region defined by the radio lobes. For TNJ0205+2242, the Ly{alpha} profile narrows significantly outside the jet radius, indicating the presence of a quiescent halo. TNJ0121+1320 has two components at a projected relative distance of {approx}10 kpc and a velocity offset of {approx}300 km s{sup -1}, measured from the [OIII]{lambda}5007 velocity map. This suggests that the fainter component is orbiting around the more massive, radio-loud galaxy. If motions are gravitational, this implies a dynamical mass of 2 x 10{sup 11} M{sub {circle_dot}} for the radio-loud component. The dynamical mass, molecular gas mass measured from the CO line emission, and radio luminosity of these two compact radio galaxies imply that compact radio sources may well develop large-scale, energetic outflows as observed in extended radio galaxies, with the potential of removing significant fractions of the ISM from the host galaxy. The absence of luminous emission line gas extending beyond the radio emission in these sources agrees with the observed timescales and outflow rates in extended radio galaxies, and adds further evidence that the energetic, large-scale outflows observed in extended radio sources (Nesvadba et al. 2006) are indeed the result of influence of the radio jet.

  18. Generating expansion model incorporating compact DC power flow equations

    SciTech Connect (OSTI)

    Nderitu, D.G.; Sparrow, F.T.; Yu, Z. [Purdue Inst. for Interdisciplinary Engineering Studies, West Lafayette, IN (United States)

    1998-12-31T23:59:59.000Z

    This paper presents a compact method of incorporating the spatial dimension into the generation expansion problem. Compact DC power flow equations are used to provide real-power flow coordination equations. Using these equations the marginal contribution of a generator to th total system loss is formulated as a function of that generator`s output. Incorporating these flow equations directly into the MIP formulation of the generator expansion problem results in a model that captures a generator`s true net marginal cost, one that includes both the cost of generation and the cost of transport. This method contrasts with other methods that iterate between a generator expansion model and an optimal power flow model. The proposed model is very compact and has very good convergence performance. A case study with data from Kenya is used to provide a practical application to the model.

  19. Anisotropic Compact Stars in $f(T)$ Gravity

    E-Print Network [OSTI]

    Abbas, G; Zubair, M

    2015-01-01T23:59:59.000Z

    This paper deals with the theoretical modeling of anisotropic compact stars in the framework of $f(T)$ theory of gravity, where $T$ is torsion scalar. To this end, we have used the exact solutions of Krori and Barua metric to a static spherically symmetric metric. The unknown constants involved in the Krori and Barua metric have been specified by using the masses and radii of compact stars 4$U$1820-30, Her X-1, SAX J 1808-3658. The physical properties of these stars have been analyzed in the framework of $f(T)$ theory. In this setting, we have checked the anisotropic behavior, regularity conditions, stability and surface redshift of the compact stars.

  20. Anisotropic Compact Stars in $f(G)$ Gravity

    E-Print Network [OSTI]

    G. Abbas; D. Momeni; M. Aamir Ali; R. Myrzakulov; S. Qaisar

    2014-12-26T23:59:59.000Z

    This paper is devoted to study the possibility of forming anisotropic compact stars in"modified Gauss-Bonnet, namely called as $f(G)$ theory of gravity which is one of the strong candidates, responsible for the accelerated expansion of the universe. For this purpose, we have used analytical solution of Krori and Barua metric to the Einstein field equations with anisotropic form of matter and power law model of $f(G)$ gravity. To determine the unknown constants in Krori and Barua metric, we have used the masses and radii of compact stars, 4$U$1820-30, Her X-1, SAX J 1808-3658. The physical behavior of these stars have been analyzed with the observational data. In this setting, we have checked all the regularity conditions and stability the compact stars 4$U$1820-30, Her X-1, SAX J 1808-3658.

  1. Anisotropic Compact Stars in $f(R)$ Gravity

    E-Print Network [OSTI]

    M. Zubair; G. Abbas

    2015-02-06T23:59:59.000Z

    In this paper we have investigated the possibility of forming of anisotropic compact stars in $f(R)$ gravity, one of the competent candidates of dark energy. To this end, we have applied the analytical solution of Krori and Barua metric to a static spherically symmetric spacetime in $f(R)$ gravity. The unknown constants in Krori and Barua metric have been determined by using masses and radii of class of compact stars like 4$U$1820-30, Her X-1, SAX J 1808-3658. The properties of these stars have been analyzes in detail. Furthermore, we have checked the regularity conditions, energy conditions, anisotropic behavior, stability and surface redshift of the compact stars 4$U$1820-30, Her X-1, SAX J 1808-3658.

  2. Anisotropic Compact Stars in $f(T)$ Gravity

    E-Print Network [OSTI]

    G. Abbas; Afshan Kanwal; M. Zubair

    2015-01-22T23:59:59.000Z

    This paper deals with the theoretical modeling of anisotropic compact stars in the framework of $f(T)$ theory of gravity, where $T$ is torsion scalar. To this end, we have used the exact solutions of Krori and Barua metric to a static spherically symmetric metric. The unknown constants involved in the Krori and Barua metric have been specified by using the masses and radii of compact stars 4$U$1820-30, Her X-1, SAX J 1808-3658. The physical properties of these stars have been analyzed in the framework of $f(T)$ theory. In this setting, we have checked the anisotropic behavior, regularity conditions, stability and surface redshift of the compact stars.

  3. Anisotropic Compact Stars in $f(G)$ Gravity

    E-Print Network [OSTI]

    Abbas, G; Ali, M Aamir; Myrzakulov, R; Qaisar, S

    2015-01-01T23:59:59.000Z

    This paper is devoted to study the possibility of forming anisotropic compact stars in"modified Gauss-Bonnet, namely called as $f(G)$ theory of gravity which is one of the strong candidates, responsible for the accelerated expansion of the universe. For this purpose, we have used analytical solution of Krori and Barua metric to the Einstein field equations with anisotropic form of matter and power law model of $f(G)$ gravity. To determine the unknown constants in Krori and Barua metric, we have used the masses and radii of compact stars, 4$U$1820-30, Her X-1, SAX J 1808-3658. The physical behavior of these stars have been analyzed with the observational data. In this setting, we have checked all the regularity conditions and stability the compact stars 4$U$1820-30, Her X-1, SAX J 1808-3658.

  4. Detection of Compact Nuclear X-Ray Emission in NGC 4736

    E-Print Network [OSTI]

    Wei Cui; Dan Feldkun; Robert Braun

    1996-10-01T23:59:59.000Z

    We report the results from a deep ROSAT PSPC observation of LINER galaxy NGC 4736. Two bright sources are detected, separated by only about 1', with the brighter one coinciding with the center of the galaxy. Neither source shows apparent X-ray variability on time-scales of minutes to hours in the ROSAT band. Simple power-law models, typical of AGN X-ray spectra, produce poor fits to the observed X-ray spectrum of the nuclear source. The addition of a Raymond-Smith component improves the fits significantly. This is consistent with the presence of hot gas in the nuclear region with kT=~0.3 keV, in addition to a compact nuclear source. However, a careful examination of the residuals reveal apparent features at low energies (< 0.25 keV). We find that the addition of a narrow emission line at about 0.22 keV is a significant improvement to the parameterization of the spectrum. We examine the results in the light of the accuracy of the PSPC spectral calibration. The derived photon index is about 2.3, which is similar to those for Seyfert 1 galaxies measured in the ROSAT energy range. On the other hand, the 0.1-2 keV luminosity for the compact source is only about 3.4x10^{39} erg/s, much fainter than typical Seyfert galaxies. We discuss the implications of these results on the connection between LINERs and AGNs. The off-center source is transient in nature. It has a hard X-ray spectrum, with a photon index of about 1.5, so is likely to be an X-ray binary. There is still some ambiguity regarding its association with the galaxy. If it is indeed located in the galaxy, the 0.1-2 keV luminosity would be greater than 5.1x10^{38} erg/s, making it a stellar-mass black hole candidate.

  5. Compact Object Formation and the Supernova Explosion Engine

    E-Print Network [OSTI]

    Fryer, C L

    2013-01-01T23:59:59.000Z

    When a massive star ends its life, its core collapses, forming a neutron star or black hole and producing some of the most energetic explosions in the universe. Core-collapse supernovae and long-duration gamma-ray bursts are the violent signatures of compact remnant formation. As such, both fields are intertwined and, coupled with theory, observations of transients can help us better understand compact remnants just as neutron star and black hole observations can constrain the supernova and gamma-ray burst engine. We review these ties in this paper.

  6. Plasma Frequency Shift Due to a Slowly Rotating Compact Star

    E-Print Network [OSTI]

    Babur M. Mirza; Hamid Saleem

    2005-05-10T23:59:59.000Z

    We investigate the effects of a slowly rotating compact gravitational source on electron oscillations in a homogeneous electrically neutral plasma in the absence of an external electric or magnetic field. Neglecting the random thermal motion of the electrons we assume the gravitoelectromagnetic approximation to the general theory of relativity for the gravitational field. It is shown that there is a shift in the plasma frequency and hence in the dielectric constant of the plasma due to the gravitomagnetic force. We also give estimates for the difference in the frequency of radially transmitted electromagnetic signals for typical compact star candidates.

  7. Compact stars in the standard model - and beyond

    E-Print Network [OSTI]

    F. Sandin

    2004-10-18T23:59:59.000Z

    In the context of the standard model of particle physics, there is a definite upper limit to the density of stable compact stars. However, if there is a deeper layer of constituents, below that of quarks and leptons, stability may be re-established far beyond this limiting density and a new class of compact stars could exist. These objects would cause gravitational lensing of white dwarfs and gamma-ray bursts, which might be observable as a diffraction pattern in the spectrum. Such observations could provide means for obtaining new clues about the fundamental particles and the origin of cold dark matter.

  8. A study of hand tamper design for compaction of soils

    E-Print Network [OSTI]

    McDonough, Brian

    1961-01-01T23:59:59.000Z

    Determination Standard Oven Dry Method versus Frying Pan Method Grain Size Distribution Curve Centerville Sand 34 Tamper Comparison Chart: Dry Density after 200 Blows per Square Foot of Layer Dry Density versus Compactive Effort Curve on 3. 0 Inch Square... of Utah revealed that a point exists at which an ultimate density is obtained, and any further increase in compaction effort results in lower than ultimate values. Shear Stress and Beari Ca acit If the resistance in a soil is exceeded by applied loads...

  9. Creation of a Compact Topologically Nontrivial Inflationary Universe

    E-Print Network [OSTI]

    Andrei Linde

    2004-09-11T23:59:59.000Z

    If inflation can occur only at the energy density V much smaller than the Planck density, which is the case for many inflationary models based on string theory, then the probability of quantum creation of a closed or an infinitely large open inflationary universe is exponentially suppressed for all known choices of the wave function of the universe. Meanwhile under certain conditions there is no exponential suppression for creation of topologically nontrivial compact flat or open inflationary universes. This suggests, contrary to the standard textbook lore, that compact flat or open universes with nontrivial topology should be considered a rule rather than an exception.

  10. Infiltration of nickel into alumina compact by electrodeposition

    SciTech Connect (OSTI)

    Hirata, Yoshihiro; Kyoda, Hideharu; Iwamoto, Takayuki [Kagoshima Univ. (Japan)

    1995-09-01T23:59:59.000Z

    Ni metal was electrodeposited into pores of an alumina compact in the aqueous solution of nickel nitrate/urea/ethylene glycol/ammonium sulfate. The Ni{sup 2+} ions in pores of the alumina compact deposited in proportion to t{sup 0.45}-t{sup 0.61} of deposition time (t) on Au electrode sputtered on the alumina surface. The deposition rate of Ni was higher for direct current than pulsed current Nickel grew dendritically in the alumina pores.

  11. Compact two-beam push-pull free electron laser

    DOE Patents [OSTI]

    Hutton, Andrew (Yorktown, VA)

    2009-03-03T23:59:59.000Z

    An ultra-compact free electron laser comprising a pair of opposed superconducting cavities that produce identical electron beams moving in opposite directions such that each set of superconducting cavities accelerates one electron beam and decelerates the other electron beam. Such an arrangement, allows the energy used to accelerate one beam to be recovered and used again to accelerate the second beam, thus, each electron beam is decelerated by a different structure than that which accelerated it so that energy exchange rather than recovery is achieved resulting in a more compact and highly efficient apparatus.

  12. Ship response using a compact wave spectrum model 

    E-Print Network [OSTI]

    Linn, Larry Donald

    1985-01-01T23:59:59.000Z

    SHIP RESPONSE USIM6 A COMPACT HAVE SPECTRUH HODEL A Thesis by LARRY DONALD LINN Submitted to the 6raduate College of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 1985 Major Subject...: Ocean Engineering SHIP RESPONSE USIN6 A COMPACT 'NAVE SPECTRUN MODEL A Thesis by LARRY DONALD LINN Approved as to style and content by: John M. Niedzwec i (Chairman of Committee) Lee L. Lowery (Member) John M. Klinck (Member) Donald Mc...

  13. Design, prototyping and testing of a compact superconducting double quarter wave crab cavity

    E-Print Network [OSTI]

    Xiao, Binping; Belomestnykh, Sergey; Ben-Zvi, Ilan; Calaga, Rama; Cullen, Chris; Capatina, Ofelia; Hammons, Lee; Li, Zenghai; Marques, Carlos; Skaritka, John; Verdú-Andres, Silvia; Wu, Qiong

    2015-01-01T23:59:59.000Z

    A novel design of superconducting Crab Cavity was proposed and designed at Brookhaven National Laboratory. The new cavity shape is a Double Quarter Wave or DQWCC. After fabrication and surface treatments, the niobium proof-of-principle cavity was cryogenically tested in a vertical cryostat. The cavity is extremely compact yet has a low frequency of 400 MHz, an essential property for service for the Large Hadron Collider luminosity upgrade. The electromagnetic properties of the cavity are also well matched for this demanding task. The demonstrated deflecting voltage of 4.6 MV is well above the requirement for a crab cavity in the future High Luminosity LHC of 3.34 MV. In this paper we present the design, prototyping and test results of the DQWCC.

  14. EFFECT OF UNCERTAINTIES IN STELLAR MODEL PARAMETERS ON ESTIMATED MASSES AND RADII OF SINGLE STARS

    SciTech Connect (OSTI)

    Basu, Sarbani [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Verner, Graham A.; Chaplin, William J.; Elsworth, Yvonne, E-mail: sarbani.basu@yale.edu, E-mail: gav@bison.ph.bham.ac.uk, E-mail: w.j.chaplin@bham.ac.uk, E-mail: y.p.elsworth@bham.ac.uk [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2012-02-10T23:59:59.000Z

    Accurate and precise values of radii and masses of stars are needed to correctly estimate properties of extrasolar planets. We examine the effect of uncertainties in stellar model parameters on estimates of the masses, radii, and average densities of solar-type stars. We find that in the absence of seismic data on solar-like oscillations, stellar masses can be determined to a greater accuracy than either stellar radii or densities; but to get reasonably accurate results the effective temperature, log g, and metallicity must be measured to high precision. When seismic data are available, stellar density is the most well-determined property, followed by radius, with mass the least well-determined property. Uncertainties in stellar convection, quantified in terms of uncertainties in the value of the mixing length parameter, cause the most significant errors in the estimates of stellar properties.

  15. A compact single-camera system for high-speed, simultaneous 3-D velocity and temperature measurements.

    SciTech Connect (OSTI)

    Lu, Louise [University of Michigan, Ann Arbor, MI; Sick, Volker [University of Michigan, Ann Arbor, MI; Frank, Jonathan H.

    2013-09-01T23:59:59.000Z

    The University of Michigan and Sandia National Laboratories collaborated on the initial development of a compact single-camera approach for simultaneously measuring 3-D gasphase velocity and temperature fields at high frame rates. A compact diagnostic tool is desired to enable investigations of flows with limited optical access, such as near-wall flows in an internal combustion engine. These in-cylinder flows play a crucial role in improving engine performance. Thermographic phosphors were proposed as flow and temperature tracers to extend the capabilities of a novel, compact 3D velocimetry diagnostic to include high-speed thermometry. Ratiometric measurements were performed using two spectral bands of laser-induced phosphorescence emission from BaMg2Al10O17:Eu (BAM) phosphors in a heated air flow to determine the optimal optical configuration for accurate temperature measurements. The originally planned multi-year research project ended prematurely after the first year due to the Sandia-sponsored student leaving the research group at the University of Michigan.

  16. The spin rate of pre-collapse stellar cores: wave driven angular momentum transport in massive stars

    E-Print Network [OSTI]

    Fuller, Jim; Lecoanet, Daniel; Quataert, Eliot

    2015-01-01T23:59:59.000Z

    The core rotation rates of massive stars have a substantial impact on the nature of core collapse supernovae and their compact remnants. We demonstrate that internal gravity waves (IGW), excited via envelope convection during a red supergiant phase or during vigorous late time burning phases, can have a significant impact on the rotation rate of the pre-SN core. In typical ($10 \\, M_\\odot \\lesssim M \\lesssim 20 \\, M_\\odot$) supernova progenitors, IGW may substantially spin down the core, leading to iron core rotation periods $P_{\\rm min,Fe} \\gtrsim 50 \\, {\\rm s}$. Angular momentum (AM) conservation during the supernova would entail minimum NS rotation periods of $P_{\\rm min,NS} \\gtrsim 3 \\, {\\rm ms}$. In most cases, the combined effects of magnetic torques and IGW AM transport likely lead to substantially longer rotation periods. However, the stochastic influx of AM delivered by IGW during shell burning phases inevitably spin up a slowly rotating stellar core, leading to a maximum possible core rotation perio...

  17. RETENTION OF STELLAR-MASS BLACK HOLES IN GLOBULAR CLUSTERS

    SciTech Connect (OSTI)

    Morscher, Meagan; Umbreit, Stefan; Farr, Will M.; Rasio, Frederic A., E-mail: m.morscher@u.northwestern.edu, E-mail: s-umbreit@northwestern.edu, E-mail: w-farr@northwestern.edu, E-mail: rasio@northwestern.edu [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States)

    2013-01-20T23:59:59.000Z

    Globular clusters should be born with significant numbers of stellar-mass black holes (BHs). It has been thought for two decades that very few of these BHs could be retained through the cluster lifetime. With masses {approx}10 M{sub Sun }, BHs are {approx}20 times more massive than an average cluster star. They segregate into the cluster core, where they may eventually decouple from the remainder of the cluster. The small-N core then evaporates on a short timescale. This is the so-called Spitzer instability. Here we present the results of a full dynamical simulation of a globular cluster containing many stellar-mass BHs with a realistic mass spectrum. Our Monte Carlo simulation code includes detailed treatments of all relevant stellar evolution and dynamical processes. Our main finding is that old globular clusters could still contain many BHs at present. In our simulation, we find no evidence for the Spitzer instability. Instead, most of the BHs remain well mixed with the rest of the cluster, with only the innermost few tens of BHs segregating significantly. Over the 12 Gyr evolution, fewer than half of the BHs are dynamically ejected through strong binary interactions in the cluster core. The presence of BHs leads to long-term heating of the cluster, ultimately producing a core radius on the high end of the distribution for Milky Way globular clusters (and those of other galaxies). A crude extrapolation from our model suggests that the BH-BH merger rate from globular clusters could be comparable to the rate in the field.

  18. Clementine Star Tracker Stellar Compass: Final report part 1

    SciTech Connect (OSTI)

    Priest, R.E.; Kordas, J.F.; Lewis, I.T. [and others

    1995-07-01T23:59:59.000Z

    The Clementine mission provided the first ever complete, systematic surface mapping of the moon from the ultra-violet to the near-infrared regions. More than 1.7 million images of the moon, earth and space were returned from this mission. Two star stracker stellar compasses (star tracker camera + stellar compass software) were included on the spacecraft, serving a primary function of providing angle updates to the guidance and navigation system. These cameras served a secondary function by providing a wide field of view imaging capability for lunar horizon glow and other dark-side imaging data. This 290 g camera using a 576 x 384 focal plane array and a 17 mm entrance pupil, detected and centroided stars as dim and dimmer than 4.5 m{sub v}, providing rms pointing accuracy of better than 100 {mu}rad pitch and yaw and 450 {mu}rad roll. A description of this light-weight, low power star tracker camera along with a summary of lessons learned is presented. Design goals and preliminary on-orbit performance estimates are addressed in terms of meeting the mission`s primary objective for flight qualifying the sensors for future Department of Defense flights. Documentation generated during the design, analysis, build, test and characterization of the star tracker cameras are presented. Collectively, this documentation represents a small library of information for this camera, and may be used as a framework for producing copy units by commercial enterprises, and therefore satisfies a Department of Defense and Department of Energy goal to transfer technology to industry. However, the considerable knowledge gained from the experience of the individuals involved in the system trades, design, analysis, production, testing and characterization of the star tracker stellar compass is not contained in this documentation.

  19. On extendability of group actions on compact Riemann surfaces

    E-Print Network [OSTI]

    Conder, Marston

    of such groups. The associated signatures appear in Table 1 below, the #12;rst eight corresponding to normalOn extendability of group actions on compact Riemann surfaces E. Bujalance #3; , F.J. Cirre y , M.D.E. Conder z 28 September 2001 Abstract The question of whether a given group G which acts faithfully

  20. Fouling characteristics of compact heat exchangers and enhanced tubes.

    SciTech Connect (OSTI)

    Panchal, C. B.; Rabas, T. J.

    1999-07-15T23:59:59.000Z

    Fouling is a complex phenomenon that (1) encompasses formation and transportation of precursors, and (2) attachment and possible removal of foulants. A basic understanding of fouling mechanisms should guide the development of effective mitigation techniques. The literature on fouling in complex flow passages of compact heat exchangers is limited; however, significant progress has been made with enhanced tubes.

  1. Disk-shaped Compact Tension Test for Asphalt Concrete Fracture

    E-Print Network [OSTI]

    Paulino, Glaucio H.

    Disk-shaped Compact Tension Test for Asphalt Concrete Fracture by M.P.Wagoner, W.G. Buttlar and G geometry is the ability to test cylindrical cores obtained from in-place asphalt concrete pavements finalizing the specimen geometry, a typical asphalt concrete surface mixture was tested at various

  2. GRI-04/0067 Evaluation of Soil Compaction

    E-Print Network [OSTI]

    & Pipeline Technology Division Gas Technology Institute 1700 South Mount Prospect Road Des Plaines, IL 60018GRI-04/0067 Evaluation of Soil Compaction Measuring Devices FINAL REPORT Prepared by Distribution Prepared for Gas Research Institute GTI Contract Number 15090 GRI Contract Number 8575 March 2005 #12;ii

  3. SURFING A WAVE TO COMPACT LASER TECHNOLOGY December 10 2007

    E-Print Network [OSTI]

    Strathclyde, University of

    to waves trailing behind a moving boat and small bunches of electrons can gather energy from the waveSURFING A WAVE TO COMPACT LASER TECHNOLOGY December 10 2007 New laser-based technology could laser pulses can be fired into plasma to create a wake and its huge electric fields can be harnessed

  4. Recent progress on the Compact Ignition Tokamak (CIT)

    SciTech Connect (OSTI)

    Ignat, D.W.

    1987-01-01T23:59:59.000Z

    This report describes work done on the Compact Ignition Tokamak (CIT), both at the Princeton Plasma Physics Laboratory (PPPL) and at other fusion laboratories in the United States. The goal of CIT is to reach ignition in a tokamak fusion device in the mid-1990's. Scientific and engineering features of the design are described, as well as projected cost and schedule.

  5. Compact Representation of Coordinated Sampling Policies for Body Sensor Networks

    E-Print Network [OSTI]

    Panangadan, Anand

    .Talukder@jpl.nasa.gov Abstract Embedded sensors of a Body Sensor Network need to efficiently utilize their energy resources Department of Electrical Engineering Los Angeles, CA 90089, USA 1-213-821-0871 {lius,raghu}@usc.edu 2 of a compact representation is feasible with little loss in performance. The global optimal policy is computed

  6. Corona performance of a compact 230-kV line

    SciTech Connect (OSTI)

    Chartier, V.L.; Blair, D.E. [Bonneville Power Administration, Vancouver, WA (United States). Division of Laboratories; Easley, M.D.; Raczkowski, R.T. [Puget Sound Power and Light Co., Bellevue, WA (United States)

    1994-12-31T23:59:59.000Z

    Permitting requirements and the acquisition of new rights-of-way for transmission facilities has in recent years become increasingly difficult for most utilities, including Puget Sound Power and Light Company. In order to maintain a high degree of reliability of service while being responsive to public concerns regarding the siting of high voltage (HV) transmission facilities, Puget Power has found it necessary to more heavily rely upon the use of compact lines in franchise corridors. Compaction does, however, precipitant increased levels of audible noise (AN) and radio and TV interference (RI and TVI) due to corona on the conductors and insulator assemblies. Puget Power relies upon the Bonneville Power Administration (BPA) Corona and Field Effects computer program to calculate AN and RI for new lines. Since there was some question of the program`s ability to accurately represent quiet 230-kV compact designs, a joint project was undertaken with BPA to verify the program`s algorithms. Long-term measurements made on an operating Puget Power 230-kV compact line confirmed the accuracy of BPA`s AN model; however, the RI measurements were much lower than predicted by the BPA computer and other programs. This paper also describes how the BPA computer program can be used to calculate the voltage needed to expose insulator assemblies to the correct electric field in single test setups in HV laboratories.

  7. Corona performance of a compact 230-kV line

    SciTech Connect (OSTI)

    Chartier, V.L.; Blair, D.E. [Bonneville Power Administration, Vancouver, WA (United States). Division of Labs.] [Bonneville Power Administration, Vancouver, WA (United States). Division of Labs.; Easley, M.D.; Raczkowski, R.T. [Puget Sound Power and Light Co., Bellevue, WA (United States)] [Puget Sound Power and Light Co., Bellevue, WA (United States)

    1995-01-01T23:59:59.000Z

    Permitting requirements and the acquisition of new rights-of-way for transmission facilities has in recent years become increasingly difficult for most utilities, including Puget Sound Power and Light Company. In order to maintain a high degree of reliability of service while being responsive to public concerns regarding the siting of high voltage (HV) transmission facilities, Puget Power has found it necessary to more heavily rely upon the use of compact lines in franchise corridors. Compaction does, however, precipitate increased levels of audible noise (AN) and radio and TV interference (RI and TVI) due to corona on the conductors and insulator assemblies. Puget Power relies upon the Bonneville Power Administration (BPA) Corona and Field Effects computer program to calculate AN and RI for new lines. Since there was some question of the program`s ability to accurately represent quiet 230-kV compact designs, a joint project was undertaken with BPA to verify the program`s algorithms. Long-term measurements made on an operating Puget Power 230-kV compact line confirmed the accuracy of BPA`s AN model; however, the RI measurements were much lower than predicted by the BPA and other programs. This paper also describes how the BPA computer program can be used to calculate the voltage needed to expose insulator assemblies to the correct electric field in single test setups in HV laboratories.

  8. A Compact Wireless Charging System for Electric Vehicles

    SciTech Connect (OSTI)

    Ning, Puqi [ORNL] [ORNL; Miller, John M [ORNL] [ORNL; Onar, Omer C [ORNL] [ORNL; White, Cliff P [ORNL] [ORNL

    2013-01-01T23:59:59.000Z

    In this paper, a compact high efficiency wireless power transfer system has been designed and developed. The detailed gate drive design, cooling system design, power stage development, and system assembling are presented. The successful tests verified the feasibility of wireless power transfer system to achieve over-all 90% efficiency.

  9. A New Compact Multichannel Receiver for Underwater Wireless Communication Networks

    E-Print Network [OSTI]

    Abdi, Ali

    size of the proposed receiver makes it particularly useful for small unmanned underwater vehicles1 A New Compact Multichannel Receiver for Underwater Wireless Communication Networks Ali Abdi of the particle velocity, in addition to the pressure, multichannel reception can be accomplished in underwater

  10. Compact anhydrous HCl to aqueous HCl conversion system

    DOE Patents [OSTI]

    Grossman, M.W.; Speer, R.

    1993-06-01T23:59:59.000Z

    The present invention is directed to an inexpensive and compact apparatus adapted for use with a [sup 196]Hg isotope separation process and the conversion of anhydrous HCl to aqueous HCl without the use of air flow to carry the HCl vapor into the converter system.

  11. Compact anhydrous HCl to aqueous HCl conversion system

    SciTech Connect (OSTI)

    Grossman, Mark W. (Belmont, MA); Speer, Richard (S. Hamilton, MA)

    1993-01-01T23:59:59.000Z

    The present invention is directed to an inexpensive and compact apparatus adapted for use with a .sup.196 Hg isotope separation process and the conversion of anhydrous HCl to aqueous HCl without the use of air flow to carry the HCl vapor into the converter system.

  12. Analysis of Time Series Using Compact Model-Based Descriptions

    E-Print Network [OSTI]

    Kriegel, Hans-Peter

    Analysis of Time Series Using Compact Model-Based Descriptions Hans-Peter Kriegel, Peer Kr this is a combination of the coefficients 1, . . . , 3 representing the three input time series using a function f-of-the-art compression methods. The results are visually presented in a very concise way so that the user can easily

  13. MissionBased Compact The Commonwealth of Australia

    E-Print Network [OSTI]

    Viglas, Anastasios

    ;Page 2 CONTENTS Attachments A. Indicative list of Commonwealth Funding provided to the University which is administered by DEEWR and relevant to this Compact. B. List of Commonwealth Funding provided to the University and Workplace Relations and the University about Performance Funding. E. Copy of Commonwealth Grant Scheme

  14. Ultra-compact Marx-type high-voltage generator

    DOE Patents [OSTI]

    Goerz, David A. (Brentwood, CA); Wilson, Michael J. (Modesto, CA)

    2000-01-01T23:59:59.000Z

    An ultra-compact Marx-type high-voltage generator includes individual high-performance components that are closely coupled and integrated into an extremely compact assembly. In one embodiment, a repetitively-switched, ultra-compact Marx generator includes low-profile, annular-shaped, high-voltage, ceramic capacitors with contoured edges and coplanar extended electrodes used for primary energy storage; low-profile, low-inductance, high-voltage, pressurized gas switches with compact gas envelopes suitably designed to be integrated with the annular capacitors; feed-forward, high-voltage, ceramic capacitors attached across successive switch-capacitor-switch stages to couple the necessary energy forward to sufficiently overvoltage the spark gap of the next in-line switch; optimally shaped electrodes and insulator surfaces to reduce electric field stresses in the weakest regions where dissimilar materials meet, and to spread the fields more evenly throughout the dielectric materials, allowing them to operate closer to their intrinsic breakdown levels; and uses manufacturing and assembly methods to integrate the capacitors and switches into stages that can be arranged into a low-profile Marx generator.

  15. Laser wakefield simulations towards development of compact particle accelerators

    E-Print Network [OSTI]

    Geddes, Cameron Guy Robinson

    Laser wakefield simulations towards development of compact particle accelerators C.G.R. Geddes1, D understanding of accelerator physics to advance beam performance and stability, and particle simulations model, France; 9 Oxford University, UK E-mail: cgrgeddes@lbl.gov Abstract. Laser driven wakefield accelerators

  16. THE CLASSIFICATION OF EXCEPTIONAL CDQL WEBS ON COMPACT COMPLEX SURFACES

    E-Print Network [OSTI]

    Pereira, Jorge Vitório

    THE CLASSIFICATION OF EXCEPTIONAL CDQL WEBS ON COMPACT COMPLEX SURFACES J. V. PEREIRA AND L. PIRIO Abstract. Codimension one webs are configurations of finitely many codi- mension one foliations in general equation among the first integrals of the foliations defining the web reminiscent of Abel's addition the

  17. Carbon RRLs Carbon RRLs towards Ultra-compact HII Regions

    E-Print Network [OSTI]

    Balser, Dana S.

    Carbon RRLs Carbon RRLs towards Ultra-compact HII Regions Dana S. Balser D. Anish Roshi (Raman (Agnes Scott College) #12;Carbon RRLs Carbon Radio Recombination Lines (RRLs) NGC 2024 (Orion B) IC 1795 (W3) Palmer et al. (1967) #12;Carbon RRLs Photodissociation Regions (PDRs) Hollenbach & Tielens (1997

  18. Compact X-ray Light Source Workshop Report

    SciTech Connect (OSTI)

    Thevuthasan, Suntharampillai; Evans, James E.; Terminello, Louis J.; Koppenaal, David W.; Manke, Kristin L.; Plata, Charity

    2012-12-01T23:59:59.000Z

    This report, produced jointly by EMSL and FCSD, is the result of a workshop held in September 2011 that examined the utility of a compact x-ray light source (CXLS) in addressing many scientific challenges critical to advancing energy science and technology.

  19. Wavelet Occupancy Grids: a Method for Compact Map Building

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Wavelet Occupancy Grids: a Method for Compact Map Building Manuel Yguel, Olivier Aycard for multi-resolution map building based on wavelets, which we call the wavelet occupancy grid (WavOG). Pai representation and data storage for large maps, under the constraints of multi-sensor real-time updates

  20. Statistical Confirmation of a Stellar Upper Mass Limit

    E-Print Network [OSTI]

    M. S. Oey; C. J. Clarke

    2005-01-07T23:59:59.000Z

    We derive the expectation value for the maximum stellar mass (m_max) in an ensemble of N stars, as a function of the IMF upper-mass cutoff (m_up) and N. We statistically demonstrate that the upper IMF of the local massive star census observed thus far in the Milky Way and Magellanic Clouds clearly exhibits a universal upper mass cutoff around 120 - 200 M_sun for a Salpeter IMF, although the result is more ambiguous for a steeper IMF.

  1. The characteristic stellar mass as a function of redshift

    E-Print Network [OSTI]

    Cathie J. Clarke; Volker Bromm

    2003-05-11T23:59:59.000Z

    We present a model for the star formation process during the initial collapse of dark matter haloes at redshifts z=0-30. We derive a simple expression for the characteristic stellar mass scale during this initial burst of star formation. In our picture, this characteristic scale reflects both the minimum temperature to which the gas can cool (determined by the metallicity and the temperature of the cosmic microwave background) and the pressure of overlying baryons in the collapsing halo. This prescription reproduces both the large mass scales found in simulations of Population III star formation and the near solar values observed for star formation at low redshift.

  2. Stellar Velocity Dispersion of the Leo A Dwarf Galaxy

    E-Print Network [OSTI]

    Warren R. Brown; Margaret J. Geller; Scott J. Kenyon; Michael J. Kurtz

    2007-05-08T23:59:59.000Z

    We measure the first stellar velocity dispersion of the Leo A dwarf galaxy, \\sigma = 9.3 +- 1.3 km/s. We derive the velocity dispersion from the radial velocities of ten young B supergiants and two HII regions in the central region of Leo A. We estimate a projected mass of 8 +- 2.7 x10^7 solar masses within a radius of 2 arcmin, and a mass to light ratio of at least 20 +- 6 M_sun/L_sun. These results imply Leo A is at least ~80% dark matter by mass.

  3. A CATALOG OF ULTRA-COMPACT HIGH VELOCITY CLOUDS FROM THE ALFALFA SURVEY: LOCAL GROUP GALAXY CANDIDATES?

    SciTech Connect (OSTI)

    Adams, Elizabeth A. K.; Giovanelli, Riccardo; Haynes, Martha P., E-mail: betsey@astro.cornell.edu, E-mail: riccardo@astro.cornell.edu, E-mail: haynes@astro.cornell.edu [Center for Radiophysics and Space Research, Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States)

    2013-05-01T23:59:59.000Z

    We present a catalog of 59 ultra-compact high velocity clouds (UCHVCs) extracted from the 40% complete ALFALFA HI-line survey. The ALFALFA UCHVCs have median flux densities of 1.34 Jy km s{sup -1}, median angular diameters of 10', and median velocity widths of 23 km s{sup -1}. We show that the full UCHVC population cannot easily be associated with known populations of high velocity clouds. Of the 59 clouds presented here, only 11 are also present in the compact cloud catalog extracted from the commensal GALFA-HI survey, demonstrating the utility of this separate dataset and analysis. Based on their sky distribution and observed properties, we infer that the ALFALFA UCHVCs are consistent with the hypothesis that they may be very low mass galaxies within the Local Volume. In that case, most of their baryons would be in the form of gas, and because of their low stellar content, they remain unidentified by extant optical surveys. At distances of {approx}1 Mpc, the UCHVCs have neutral hydrogen (H I) masses of {approx}10{sup 5}-10{sup 6} M{sub Sun }, H I diameters of {approx}2-3 kpc, and indicative dynamical masses within the H I extent of {approx}10{sup 7}-10{sup 8} M{sub Sun }, similar to the Local Group ultra-faint dwarf Leo T. The recent ALFALFA discovery of the star-forming, metal-poor, low mass galaxy Leo P demonstrates that this hypothesis is true in at least one case. In the case of the individual UCHVCs presented here, confirmation of their extragalactic nature will require further work, such as the identification of an optical counterpart to constrain their distance.

  4. A Large Stellar Evolution Database for Population Synthesis Studies. III. Inclusion of the full Asymptotic Giant Branch phase and Web tools for stellar population analyses

    E-Print Network [OSTI]

    Daniel Cordier; Adriano Pietrinferni; Santi Cassisi; Maurizio Salaris

    2006-12-21T23:59:59.000Z

    Stellar evolution tracks and isochrones are key inputs for a wide range of astrophysical studies; in particular, they are essential to the interpretation of photometric and spectroscopic observations of resolved and unresolved stellar populations. We have made available to the astrophysical community a large, homogenous database of up-to-date stellar tracks and isochrones, and a set of programs useful in population synthesis studies. In this paper we first summarize the main properties of our stellar model database (BaSTI) already introduced in Pietrinferni et al. (2004) and Pietrinferni et al. (2006). We then discuss an important update of the database, i.e., the extension of all stellar models and isochrones until the end of the thermal pulses along the Asymptotic Giant Branch. This extension of the library is particularly relevant for stellar population analyses in the near-infrared, or longer wavelengths, where the contribution to the integrated photometric properties by cool and bright Asymptotic Giant Branch stars is significant. A few comparisons with empirical data are also presentend and briefly discussed. We then present three web-tools that allow an interactive access to the database, and make possible to compute user-specified evolutionary tracks, isochrones, stellar luminosity functions, plus synthetic Color-Magnitude-Diagrams and integrated magnitudes for arbitrary Star Formation Histories. All these web tools are available at the BaSTI database official site: http://www.oa-teramo.inaf.it/BASTI.

  5. Ceramographic Examinations of Irradiated AGR-1 Fuel Compacts

    SciTech Connect (OSTI)

    Paul Demkowicz; Scott Ploger; John Hunn; Jay S. Kehn

    2012-09-01T23:59:59.000Z

    The AGR 1 experiment involved irradiating 72 cylindrical fuel compacts containing tri-structural isotropic (TRISO)-coated particles to a peak burnup of 19.5% fissions per initial metal atom with no in-pile failures observed out of almost 300,000 particles. Six irradiated AGR 1 fuel compacts were selected for microscopy that span a range of irradiation conditions (temperature, burnup, and fast fluence). These six compacts also included all four TRISO coating variations irradiated in the AGR experiment. The six compacts were cross-sectioned both transversely and longitudinally, mounted, ground, and polished after development of careful techniques for preserving particle structures against preparation damage. From 36 to 79 particles within each cross section were exposed near enough to midplane for optical microscopy of kernel, buffer, and coating behavior. The microstructural analysis focused on kernel swelling and porosity, buffer densification and fracture, debonding between the buffer and inner pyrolytic carbon (IPyC) layers, and fractures in the IPyC and SiC layers. Three basic particle morphologies were established according to the extent of bonding between the buffer and IPyC layers: complete debonding along the interface (Type A), no debonding along the interface (Type B), and partial debonding (Type AB). These basic morphologies were subdivided according to whether the buffer stayed intact or fractured. The resulting six characteristic morphologies were used to classify particles within each cross section, but no spatial patterns were clearly observed in any of the cross-sectional morphology maps. Although positions of particle types appeared random within compacts, examining a total of 931 classified particles allowed other relationships among morphological types to be established.

  6. Ceramographic Examinations of Irradiated AGR-1 Fuel Compacts

    SciTech Connect (OSTI)

    Paul Demkowicz; Scott Ploger; John Hunn

    2012-05-01T23:59:59.000Z

    The AGR 1 experiment involved irradiating 72 cylindrical fuel compacts containing tri-structural isotropic (TRISO)-coated particles to a peak burnup of 19.5% fissions per initial metal atom with no in-pile failures observed out of almost 300,000 particles. Five irradiated AGR 1 fuel compacts were selected for microscopy that span a range of irradiation conditions (temperature, burnup, and fast fluence). These five compacts also included all four TRISO coating variations irradiated in the AGR experiment. The five compacts were cross-sectioned both transversely and longitudinally, mounted, ground, and polished after development of careful techniques for preserving particle structures against preparation damage. Approximately 40 to 80 particles within each cross section were exposed near enough to mid-plane for optical microscopy of kernel, buffer, and coating behavior. The microstructural analysis focused on kernel swelling and porosity, buffer densification and fracture, debonding between the buffer and inner pyrolytic carbon (IPyC) layers, and fractures in the IPyC and SiC layers. Three basic particle morphologies were established according to the extent of bonding between the buffer and IPyC layers: complete debonding along the interface (Type A), no debonding along the interface (Type B), and partial debonding (Type AB). These basic morphologies were subdivided according to whether the buffer stayed intact or fractured. The resulting six characteristic morphologies were used to classify particles within each cross section, but no spatial patterns were clearly observed in any of the cross-sectional morphology maps. Although positions of particle types appeared random within compacts, examining a total of 830 classified particles allowed other relationships among morphological types to be established.

  7. Extremely Compact Massive Galaxies at 1.7

    E-Print Network [OSTI]

    Fernando Buitrago; Ignacio Trujillo; Christopher J. Conselice

    2008-11-18T23:59:59.000Z

    We measure and analyse the sizes of 82 massive (M >= 10^11 M_Sun) galaxies at 1.72. We split our sample into disk-like (Sersic index n2) galaxies, and find that at a given stellar mass, disk-like galaxies at z~2.3 are a factor of 2.6+/-0.3 smaller than present day equal mass systems, and spheroid-like galaxies at the same redshift are 4.3+/-0.7 times smaller than comparatively massive elliptical galaxies today. We furthermore show that the stellar mass densities of very massive galaxies at z~2.5 are similar to present-day globular clusters with values ~2x10^10 M_Sun kpc^-3

  8. A FIRST LOOK AT THE AURIGA-CALIFORNIA GIANT MOLECULAR CLOUD WITH HERSCHEL AND THE CSO: CENSUS OF THE YOUNG STELLAR OBJECTS AND THE DENSE GAS

    SciTech Connect (OSTI)

    Harvey, Paul M. [Astronomy Department, University of Texas at Austin, 1 University Station C1400, Austin, TX 78712-0259 (United States)] [Astronomy Department, University of Texas at Austin, 1 University Station C1400, Austin, TX 78712-0259 (United States); Fallscheer, Cassandra [Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2 (Canada)] [Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2 (Canada); Ginsburg, Adam [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309-0389 (United States)] [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309-0389 (United States); Terebey, Susan [Department of Physics and Astronomy PS315, 5151 State University Drive, California State University at Los Angeles, Los Angeles, CA 90032 (United States)] [Department of Physics and Astronomy PS315, 5151 State University Drive, California State University at Los Angeles, Los Angeles, CA 90032 (United States); Andre, Philippe; Koenyves, Vera [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, IRFU/Service d'Astrophysique, CEA Saclay, F-91191 Gif-sur-Yvette (France)] [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, IRFU/Service d'Astrophysique, CEA Saclay, F-91191 Gif-sur-Yvette (France); Bourke, Tyler L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)] [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Di Francesco, James; Matthews, Brenda C. [Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada)] [Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Peterson, Dawn E., E-mail: pmh@astro.as.utexas.edu, E-mail: Cassandra.Fallscheer@nrc-cnrc.gc.ca, E-mail: adam.ginsburg@colorado.edu, E-mail: sterebe@calstatela.edu, E-mail: pandre@cea.fr, E-mail: vera.konyves@cea.fr, E-mail: tbourke@cfa.harvard.edu, E-mail: James.DiFrancesco@nrc-cnrc.gc.ca, E-mail: Brenda.Matthews@nrc-cnrc.gc.ca, E-mail: dpeterson@spacescience.org [Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80303 (United States)

    2013-02-20T23:59:59.000Z

    We have mapped the Auriga/California molecular cloud with the Herschel PACS and SPIRE cameras and the Bolocam 1.1 mm camera on the Caltech Submillimeter Observatory with the eventual goal of quantifying the star formation and cloud structure in this giant molecular cloud (GMC) that is comparable in size and mass to the Orion GMC, but which appears to be forming far fewer stars. We have tabulated 60 compact 70/160 {mu}m sources that are likely pre-main-sequence objects and correlated those with Spitzer and WISE mid-IR sources. At 1.1 mm, we find 18 cold, compact sources and discuss their properties. The most important result from this part of our study is that we find a modest number of additional compact young objects beyond those identified at shorter wavelengths with Spitzer. We also describe the dust column density and temperature structure derived from our photometric maps. The column density peaks at a few Multiplication-Sign 10{sup 22} cm{sup -2} (N {sub H2}) and is distributed in a clear filamentary structure along which nearly all of the pre-main-sequence objects are found. We compare the young stellar object surface density to the gas column density and find a strong nonlinear correlation between them. The dust temperature in the densest parts of the filaments drops to {approx}10 K from values {approx}14-15 K in the low-density parts of the cloud. We also derive the cumulative mass fraction and probability density function of material in the cloud, which we compare with similar data on other star-forming clouds.

  9. Safe and compact ammonia storage/delivery systems for SCR-DeNOX...

    Energy Savers [EERE]

    Safe and compact ammonia storagedelivery systems for SCR-DeNOX in automotive units Safe and compact ammonia storagedelivery systems for SCR-DeNOX in automotive units Presentation...

  10. Northwest Interstate Compact on Low-Level Radioactive Waste Management (Multiple States)

    Broader source: Energy.gov [DOE]

    The Northwest Interstate Compact on Low-Level Radioactive Waste Management, enacted in 1981, was ratified by Congress in 1985. The Compact is a cooperative effort of the party states to protect...

  11. Brookhaven National Laboratory National Synchrotron Light Source

    E-Print Network [OSTI]

    Ohta, Shigemi

    Brookhaven National Laboratory National Synchrotron Light Source Number: Revision: LS-ESH-0027 06 copy of this file is the one on-line in the NSLS ESH website. Before using a printed copy, verify that it is the most current version by checking the document issue date on the NSLS ESH website. BROOKHAVEN NATIONAL

  12. Brookhaven National Laboratory National Synchrotron Light Source

    E-Print Network [OSTI]

    Ohta, Shigemi

    Brookhaven National Laboratory National Synchrotron Light Source Number: Revision: PS-ESH-0025 01 of this file is the one on-line in the NSLS ESH website. Before using a printed copy, verify that it is the most current version by checking the document issue date on the NSLS ESH website. BROOKHAVEN NATIONAL

  13. Brookhaven National Laboratory National Synchrotron Light Source

    E-Print Network [OSTI]

    Ohta, Shigemi

    Brookhaven National Laboratory National Synchrotron Light Source Number: Revision: LS-ESH-0026 4 of this file is the one on-line in the PS ESH website. Before using a printed copy, verify that it is the most current version by checking the document issue date on the PS ESH website. BROOKHAVEN NATIONAL LABORATORY

  14. The Formation of Brown Dwarfs as Ejected Stellar Embryos

    E-Print Network [OSTI]

    Bo Reipurth; Cathie Clarke

    2001-03-01T23:59:59.000Z

    We conjecture that brown dwarfs are substellar objects because they have been ejected from small newborn multiple systems which have decayed in dynamical interactions. In this view, brown dwarfs are stellar embryos for which the star formation process was aborted before the hydrostatic cores could build up enough mass to eventually start hydrogen burning. The disintegration of a small multiple system is a stochastic process, which can be described only in terms of the half-life of the decay. A stellar embryo competes with its siblings in order to accrete infalling matter, and the one that grows slowest is most likely to be ejected. With better luck, a brown dwarf would therefore have become a normal star. This interpretation of brown dwarfs readily explains the rarity of brown dwarfs as companions to normal stars (aka the ``brown dwarf desert''), the absence of wide brown dwarf binaries, and the flattening of the low mass end of the initial mass function. Possible observational tests of this scenario include statistics of brown dwarfs near Class 0 sources, and the kinematics of brown dwarfs in star forming regions while they still retain a kinematic signature of their expulsion. Because the ejection process limits the amount of gas brought along in a disk, it is predicted that substellar equivalents to the classical T Tauri stars should be very rare.

  15. The Expulsion of Stellar Envelopes in Core-Collapse Supernovae

    E-Print Network [OSTI]

    Christopher D. Matzner; Christopher F. McKee

    1998-07-04T23:59:59.000Z

    We examine the relation between presupernova stellar structure and the distribution of ejecta in core-collapse supernovae, assuming adiabatic, spherically symmetric flow. We develop a simple yet accurate formula for the blastwave shock velocity, and demonstrate that the entire final density distribution can be approximated with simple models for the final pressure distribution, along with the approximate shock-deposited entropy, in a way that matches the results of simulations. We find that the distribution of density in a star's ejecta depends on whether its outer envelope is radiative or convective, and if convective, on the composition structure of the star; simple approximate forms are presented for red and blue supergiant ejecta. Our models are most accurate for the high-velocity ejecta from the periphery of a star, where the shock dynamics are predictable. We present formulae for the final density distribution of this material, for both radiative and efficiently convective envelopes. These formulae limit to the well-known planar, self-similar solutions for mass shells approaching the stellar surface. But, the assumption of adiabatic flow fails at low optical depth, so this planar limit need not be attained. Formulae are given for the observable properties of the X-ray burst accompanying shock emergence, and their dependence on the parameters of the explosion. Motivated by the relativistic expansion recently inferred by Kulkarni et al. (1998) for the synchrotron shell around SN1998bw, we estimate the criterion for relativistic mass ejection and the rest mass of relativistic ejecta.

  16. Discovery of a Faint Old Stellar System at 150 kpc

    E-Print Network [OSTI]

    T. Sakamoto; T. Hasegawa

    2006-10-29T23:59:59.000Z

    We report the detection of a faint old stellar system at $(\\alpha,\\delta)=(194.29^\\circ,~34.32^\\circ)$ (SDSS J1257+3419), based on the spatial distribution of bright red-giant branch stars in the Sloan Digital Sky Survey Data Release 4. SDSS J1257+3419 has a half-light radius of $38\\pm 12$ pc and an absolute integrated $V$-magnitude of $M_V=-4.8^{+1.4}_{-1.0}$ mag at a heliocentric distance of $150\\pm 15$ kpc. A comparison between SDSS J1257+3419 and known Galactic halo objects suggests that SDSS J1257+3419 is either (a) a faint and small dwarf galaxy or (b) a faint and widely extended globular cluster. In the former case, SDSS J1257+3419 could represent an entity of a postulated subhalo of the Milky Way. Further photometric and dynamical study of this stellar system is vital to discriminate these possibilities.

  17. ANALYTICAL CALCULATION OF STOKES PROFILES OF ROTATING STELLAR MAGNETIC DIPOLE

    SciTech Connect (OSTI)

    Martinez Gonzalez, M. J. [Instituto de Astrofisica de Canarias, Via Lactea s/n, 38200 La Laguna, Tenerife (Spain); Asensio Ramos, A. [Departamento de Astrofisica, Universidad de La Laguna, E-38205 La Laguna, Tenerife (Spain)

    2012-08-20T23:59:59.000Z

    The observation of the polarization emerging from a rotating star at different phases opens up the possibility to map the magnetic field in the stellar surface thanks to the well-known Zeeman-Doppler imaging. When the magnetic field is sufficiently weak, the circular and linear polarization profiles locally in each point of the star are proportional to the first and second derivatives of the unperturbed intensity profile, respectively. We show that the weak-field approximation (for weak lines in the case of linear polarization) can be generalized to the case of a rotating star including the Doppler effect and taking into account the integration on the stellar surface. The Stokes profiles are written as a linear combination of wavelength-dependent terms expressed as series expansions in terms of Hermite polynomials. These terms contain the surface-integrated magnetic field and velocity components. The direct numerical evaluation of these quantities is limited to rotation velocities not larger than eight times the Doppler width of the local absorption profiles. Additionally, we demonstrate that in a rotating star, the circular polarization flux depends on the derivative of the intensity flux with respect to the wavelength and also on the profile itself. Likewise, the linear polarization depends on the profile and on its first and second derivatives with respect to the wavelength. We particularize the general expressions to a rotating dipole.

  18. Does the stellar disc flattening depend on the galaxy type?

    E-Print Network [OSTI]

    Mosenkov, A V; Reshetnikov, V P; Bizyaev, D V; Kautsch, S J

    2015-01-01T23:59:59.000Z

    We analyze the dependence of the stellar disc flatness on the galaxy morphological type using 2D decomposition of galaxies from the reliable subsample of the Edge-on Galaxies in SDSS (EGIS) catalogue. Combining these data with the retrieved models of the edge-on galaxies from the Two Micron All Sky Survey (2MASS) and the Spitzer Survey of Stellar Structure in Galaxies (S$^4$G) catalogue, we make the following conclusions: (1) The disc relative thickness $z_0/h$ in the near- and mid-infrared passbands correlates weakly with morphological type and does not correlate with the bulge-to-total luminosity ratio $B/T$ in all studied bands. (2) Applying an 1D photometric profile analysis overestimates the disc thickness in galaxies with large bulges making an illusion of the relationship between the disc flattening and the ratio $B/T$. (3) In our sample the early-type disc galaxies (S0/a) have both flat and "puffed" discs. The early spirals and intermediate-type galaxies have a large scatter of the disc flatness, whic...

  19. Steam-circuit Model for the Compact Linear Fresnel Reflector , G. L. Morrison1

    E-Print Network [OSTI]

    Steam-circuit Model for the Compact Linear Fresnel Reflector Prototype J. D. Pye1 , G. L. Morrison1.pye@student.unsw.edu.au Abstract The Compact Linear Fresnel Reflector (CLFR) is a linear-concentrating solar thermal energy system The Compact Linear Fresnel Reflector (CLFR) was first conceived of in 1992-1993 and was patented in 1995

  20. Prediction of Asphalt Mixture Compactability from Mixture, Asphalt, and Aggregate Properties

    E-Print Network [OSTI]

    Muras, Andrew J.

    2010-07-14T23:59:59.000Z

    . Predicted Plot of CV Neural Net of Entire Data Set for a ............................ 50 Figure 32. Predicted Plot of CV Neural Net of Entire Data Set for AV Nini ................... 51 Figure 33. a versus Predicted a... ................................................... 24 Table 5 HMA Mixing and Compaction Temperatures ............................................. 27 Table 6 Compaction Parameters a, c, and AV Nini ................................................... 38 Table 7 Compaction Parameters m1, m2...

  1. Dartmouth Stellar Evolution Database and the ACS Survey of Galactic Globular Clusters II. Stellar Evolution Tracks, Isochrones, Luminosity Functions, and Synthetic Horizontal-Branch Models

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Dotter, A; Chaboyer, B; Jevremovic, D; Kostov, V; Baron, E; Ferguson, J; Sarajedini, A; Anderson, J

    Web tools are also available at the home page (http://stellar.dartmouth.edu/~models/index.html). These tools allow users to create isochrones and convert them to luminosity functions or create synthetic horizontal branch models.

  2. National Science Bowl Finals

    ScienceCinema (OSTI)

    None

    2010-09-01T23:59:59.000Z

    National Science Bowl finals and awards at the National Building Museum in Washington D.C. Monday 5/3/2010

  3. Sandia National Laboratories: solar

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

    Interactive Tour Operated by Sandia National Laboratories for the U.S. Department of Energy (DOE), the National Solar Thermal Test Facility (NSTTF) is the only test facility...

  4. Sandia National Laboratories: PV

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

    2014 Sandia Corporation | Questions & Comments | Privacy & Security U.S. Department of Energy National Nuclear Security Administration Sandia National Laboratories is a...

  5. Sandia National Laboratories: Energy

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

    National Solar Thermal Test Facility, News, News & Events, Partnership, Renewable Energy, Solar, Solar Newsletter On November 24, 2012 the National Solar Thermal Test...

  6. Sandia National Laboratories: ACEC

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

    ACEC Sandia Solar Energy Test System Cited in National Engineering Competition On May 16, 2013, in Concentrating Solar Power, Energy, Energy Storage, Facilities, National Solar...

  7. National Science Bowl Finals

    SciTech Connect (OSTI)

    2010-05-03T23:59:59.000Z

    National Science Bowl finals and awards at the National Building Museum in Washington D.C. Monday 5/3/2010

  8. National Nuclear Security Administration

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

    and Related Structures within TA-3 at Los Alamos National Laboratory, Los Alamos, New Mexico U. S. Department of Energy National Nuclear Security Administration Los Alamos Area...

  9. Confirmed: Stellar Behemoth Self-Destructs in Type IIb Supernova

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

    National Laboratory (Berkeley Lab), to expose fleeting cosmic events such as supernovae. For the first time ever, scientists have direct confirmation that a Wolf-Rayet...

  10. THE COMPACT, TIME-VARIABLE RADIO SOURCE PROJECTED INSIDE W3(OH): EVIDENCE FOR A PHOTOEVAPORATED DISK?

    SciTech Connect (OSTI)

    Dzib, Sergio A.; Rodriguez-Garza, Carolina B.; Rodriguez, Luis F.; Kurtz, Stan E.; Loinard, Laurent; Zapata, Luis A.; Lizano, Susana, E-mail: s.dzib@crya.unam.mx [Centro de Radiostronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, Morelia 58089 (Mexico)

    2013-08-01T23:59:59.000Z

    We present new Karl G. Jansky Very Large Array (VLA) observations of the compact ({approx}0.''05), time-variable radio source projected near the center of the ultracompact H II region W3(OH). The analysis of our new data as well as of VLA archival observations confirms the variability of the source on timescales of years and for a given epoch indicates a spectral index of {alpha} = 1.3 {+-} 0.3 (S{sub {nu}}{proportional_to}{nu}{sup {alpha}}). This spectral index and the brightness temperature of the source ({approx}6500 K) suggest that we are most likely detecting partially optically thick free-free radiation. The radio source is probably associated with the ionizing star of W3(OH), but an interpretation in terms of an ionized stellar wind fails because the detected flux densities are orders of magnitude larger than expected. We discuss several scenarios and tentatively propose that the radio emission could arise in a static ionized atmosphere around a fossil photoevaporated disk.

  11. D-brane field theory on compact spaces

    E-Print Network [OSTI]

    Washington Taylor

    1996-11-07T23:59:59.000Z

    We consider Dirichlet p-branes in type II string theory on a space which has been toroidally compactified in d dimensions. We give an explicit construction of the field theory description of this system by putting a countably infinite number of copies of each brane on the noncompact covering space, and modding out the resulting gauge theory by Z^d. The resulting theory is a gauge theory with graded fields corresponding to strings winding around the torus an arbitrary number of times. In accordance with T-duality, this theory is equivalent to the gauge theory for the dual system of (d + p)-branes wrapped around the compact directions, where the winding number is exchanged for momentum in the compact direction.

  12. Compact and mobile high resolution PET brain imager

    DOE Patents [OSTI]

    Majewski, Stanislaw (Yorktown, VA); Proffitt, James (Newport News, VA)

    2011-02-08T23:59:59.000Z

    A brain imager includes a compact ring-like static PET imager mounted in a helmet-like structure. When attached to a patient's head, the helmet-like brain imager maintains the relative head-to-imager geometry fixed through the whole imaging procedure. The brain imaging helmet contains radiation sensors and minimal front-end electronics. A flexible mechanical suspension/harness system supports the weight of the helmet thereby allowing for patient to have limited movements of the head during imaging scans. The compact ring-like PET imager enables very high resolution imaging of neurological brain functions, cancer, and effects of trauma using a rather simple mobile scanner with limited space needs for use and storage.

  13. A comparative study of the i-mode in stellarator and tokamak geometries

    E-Print Network [OSTI]

    A comparative study of the i-mode in stellarator and tokamak geometries J. Anderson, T. Rafiq, M the anomalous transport in present tokamaks. An advanced fluid model is applied for the ion physics whereas and the perpendicular wavenumber( )k on different magnetic surfaces in stellarator and tokamak equilibria. Quantitative

  14. stellar populations of early-type galaxies in the ATLAS^^sample

    E-Print Network [OSTI]

    Bureau, Martin

    , F-69230 Saint Genis Laval; CNRS, UMR 5574; ENS de Lyon, France ^LaboratoireAIM, CEA-SaclaylDSM/IRFU/SAp the ATLAS^^ project and our first results on the stellar populations of galaxies in the ATLAS^^ sample based Early-type galaxies (ETGs) are stellar systems with no evidence of spiral arms and in many cases

  15. A TIME DELAY MODEL FOR SOLAR AND STELLAR DYNAMOS A. L. Wilmot-Smith

    E-Print Network [OSTI]

    Dundee, University of

    A TIME DELAY MODEL FOR SOLAR AND STELLAR DYNAMOS A. L. Wilmot-Smith School of Mathematics of Dundee, 23 Perth Road, Dundee, DD1 4HN, UK and P. C. H. Martens Department of Physics, Montana State dynamos operating in stellar interiors produce the diverse range of magnetic activity ob- served in solar

  16. Lithium in cool stellar atmospheres: Big bang nucleosynthesis and extrasolar planets

    E-Print Network [OSTI]

    Lithium in cool stellar atmospheres: Big bang nucleosynthesis and extrasolar planets Matthias Steffen and Elisabetta Caffau Sternphysik In metal-poor stellar atmospheres, the Lithium line at 6707 Ã?-NLTE, respectively. The accurate spectroscopic determination of the Lithium abundance and in particular the 6Li/7Li

  17. A Source Classification Algorithm for Astronomical X-ray Imagery of Stellar Clusters

    E-Print Network [OSTI]

    Salvaggio, Carl

    A Source Classification Algorithm for Astronomical X-ray Imagery of Stellar Clusters by Susan M of Dissertation: A Source Classification Algorithm for Astronomical X-ray Imagery of Stellar Clusters I, Susan M. Hojnacki, hereby grant permission to Wallace Memorial Library of R.I.T. to reproduce my dissertation

  18. Fuel Accident Condition Simulator (FACS) Furnace for Post-Irradiation Heating Tests of VHTR Fuel Compacts

    SciTech Connect (OSTI)

    Paul A Demkowicz; Paul Demkowicz; David V Laug

    2010-10-01T23:59:59.000Z

    Abstract –Fuel irradiation testing and post-irradiation examination are currently in progress as part of the Next Generation Nuclear Plant Fuels Development and Qualification Program. The PIE campaign will include extensive accident testing of irradiated very high temperature reactor fuel compacts to verify fission product retention characteristics at high temperatures. This work will be carried out at both the Idaho National Laboratory (INL) and the Oak Ridge National Laboratory, beginning with accident tests on irradiated fuel from the AGR-1 experiment in 2010. A new furnace system has been designed, built, and tested at INL to perform high temperature accident tests. The Fuel Accident Condition Simulator furnace system is designed to heat fuel specimens at temperatures up to 2000°C in helium while monitoring the release of volatile fission metals (e.g. Cs, Ag, Sr, Eu, and I) and fission gases (Kr, Xe). Fission gases released from the fuel to the sweep gas are monitored in real time using dual cryogenic traps fitted with high purity germanium detectors. Condensable fission products are collected on a plate attached to a water-cooled cold finger that can be exchanged periodically without interrupting the test. Analysis of fission products on the condensation plates involves dry gamma counting followed by chemical analysis of selected isotopes. This paper will describe design and operational details of the Fuel Accident Condition Simulator (FACS) furnace system, as well as preliminary system calibration results.

  19. Flaw-detection characteristics of the compact MIB-4 betatron

    SciTech Connect (OSTI)

    Boiko, D.A.; Filimonov, A.A.; Chakhlov, V.L.

    1987-09-01T23:59:59.000Z

    The compact pulse betatron using electrons accelerated to an energy of up to 4 MeV (MIB-4) is designed for the radiographic inspection of reinforced-concrete structures and buildings, welded joints, various materials, and assemblies. Information which refines and complements the method of inspecting parts by means of the MIB-4 device is provided. The results obtained in testing this equipment abroad are given.

  20. Compact betatron with four controlling-field periodicity elements

    SciTech Connect (OSTI)

    Chakhlov, V.L.; Pushin, V.S.; Burov, G.I.; Zvontsov, A.A.; Zvorygin, V.P.; Zrelov, Yu.D.

    1987-01-01T23:59:59.000Z

    A compact 3-MeV betatron is described. The electromagnet of the betatron uses removable four-element poles, which form a magnetic field with azimuthal variation. The betatron accelerates 2 x 10/sup 10/ particles per cycle. The cycle repetition frequency is up to 400 Hz. The radius of the equilibrium orbit is 4.5 cm. The maximum interpole gap is 4 cm. The depth of magnetic-field variation on the equilibrium radius is 0.15.

  1. Microscopic analysis of irradiated AGR-1 coated particle fuel compacts

    SciTech Connect (OSTI)

    Scott A. Ploger; Paul A. Demkowicz; John D. Hunn; Jay S. Kehn

    2014-05-01T23:59:59.000Z

    The AGR-1 experiment involved irradiation of 72 TRISO-coated particle fuel compacts to a peak compact-average burnup of 19.5% FIMA with no in-pile failures observed out of 3 x 105 total particles. Irradiated AGR-1 fuel compacts have been cross-sectioned and analyzed with optical microscopy to characterize kernel, buffer, and coating behavior. Six compacts have been examined, spanning a range of irradiation conditions (burnup, fast fluence, and irradiation temperature) and including all four TRISO coating variations irradiated in the AGR-1 experiment. The cylindrical specimens were sectioned both transversely and longitudinally, then polished to expose from 36 to 79 individual particles near midplane on each mount. The analysis focused primarily on kernel swelling and porosity, buffer densification and fracturing, buffer–IPyC debonding, and fractures in the IPyC and SiC layers. Characteristic morphologies have been identified, 981 particles have been classified, and spatial distributions of particle types have been mapped. No significant spatial patterns were discovered in these cross sections. However, some trends were found between morphological types and certain behavioral aspects. Buffer fractures were found in 23% of the particles, and these fractures often resulted in unconstrained kernel protrusion into the open cavities. Fractured buffers and buffers that stayed bonded to IPyC layers appear related to larger pore size in kernels. Buffer–IPyC interface integrity evidently factored into initiation of rare IPyC fractures. Fractures through part of the SiC layer were found in only four classified particles, all in conjunction with IPyC–SiC debonding. Compiled results suggest that the deliberate coating fabrication variations influenced the frequencies of IPyC fractures and IPyC–SiC debonds.

  2. Simple and Compact Expressions for Neutrino Oscillation Probabilities in Matter

    E-Print Network [OSTI]

    Minakata, Hisakazu

    2015-01-01T23:59:59.000Z

    We reformulate perturbation theory for neutrino oscillations in matter with an expansion parameter related to the ratio of the solar to the atmospheric Delta m^2 scales. Unlike previous works, we use a renormalized basis in which certain first-order effects are taken into account in the zeroth-order Hamiltonian. Using this perturbation theory we derive extremely compact expressions for the neutrino oscillation probabilities in matter. We find, for example, that the $\

  3. Compact gas-insulated transformer. Fourteenth quarterly report

    SciTech Connect (OSTI)

    Not Available

    1983-08-01T23:59:59.000Z

    Objective is to develop a compact, more efficient, quieter transformer which does not rely on mineral oil insulation. Compressed SF/sub 6/ is used as the external insulation and polymer film as the insulation between turns. A separate liquid cooling system is also provided. This document reports progress made in design, mechanical, dielectric, short circuit, thermal, materials, prototype, accessories, commercialization, and system studies. (DLC)

  4. Compact-range coordinate system established using a laser tracker.

    SciTech Connect (OSTI)

    Gallegos, Floyd H.; Bryce, Edwin Anthony

    2006-12-01T23:59:59.000Z

    Establishing a Cartesian coordinate reference system for an existing Compact Antenna Range using the parabolic reflector is presented. A SMX (Spatial Metrix Corporation) M/N 4000 laser-based coordinate measuring system established absolute coordinates for the facility. Electric field characteristics with positional movement correction are evaluated. Feed Horn relocation for alignment with the reflector axis is also described. Reference points are established for follow-on non-laser alignments utilizing a theodolite.

  5. Compact Refractive Imaging Spectrometer Designs Utilizing Immersed Gratings

    DOE Patents [OSTI]

    Lerner, Scott A. (Livermore, CA); Bennett, Charles L. (Livermore, CA); Bixler, Jay V. (Oakland, CA); Kuzmenko, Paul J. (Livermore, CA); Lewis, Isabella T. (San Jose, CA)

    2005-07-26T23:59:59.000Z

    A compact imaging spectrometer comprising an entrance slit for directing light, a first means for receiving the light and focusing the light, an immersed diffraction grating that receives the light from the first means and defracts the light, a second means for receiving the light from the immersed diffraction grating and focusing the light, and an image plane that receives the light from the second means

  6. Hot subdwarfs - Small stars marking important events in stellar evolution

    E-Print Network [OSTI]

    Geier, S

    2015-01-01T23:59:59.000Z

    Hot subdwarfs are considered to be the compact helium cores of red giants, which lost almost their entire hydrogen envelope. What causes this enormous mass loss is still unclear. Binary interactions are invoked and a significant fraction of the hot subdwarf population is indeed found in close binaries. In a large project we search for the close binary sdBs with the most and the least massive companions. Significantly enhancing the known sample of close binary sdBs we performed the first comprehensive study of this population. Triggered by the discovery of two sdB binaries with close brown dwarf companions in the course of this project, we were able to show that the interaction of stars with substellar companions is an important channel to form sdB stars. Finally, we discovered a unique and very compact binary system consisting of an sdB and a massive white dwarf, which qualifies as progenitor candidate for a supernova type Ia. In addition to that, we could connect those explosions to the class of hypervelocit...

  7. Ultra-Compact High-Efficiency Luminaire for General Illumination

    SciTech Connect (OSTI)

    Ted Lowes

    2012-04-08T23:59:59.000Z

    Cree has developed a new ultra-compact light emitting diode (LED) luminaire capable of providing high efficacy with excellent color quality that can lead to significant energy savings in todayâ??s commercial and retail applications. This success was based on an integrated development effort tailoring the LED component characteristics, optics, thermal management and driver design for the small footprint to achieve an overall system efficiency of â?¥ 70%. A new LED component was designed to provide high brightness and efficacy in a form factor that allowed for a small directional beam with a luminaire housing design able to dissipate the heat effectively using a small physical envelope. A very compact, 90% efficient driver was developed to meet the system performance while not taking away any thermal mass from the heat sink. A 91% efficient secondary optics was designed to maximize efficiency while providing a smooth beam. The reliability of the new LED component was robust under accelerated testing conditions. Luminaires were assembled integrating the novel LED component, secondary optics, heat sink and driver technology to demonstrate the system improvement. Cree has successfully completed this project by developing an ultra-compact LED luminaire that provided 380 lumens at a correlated color temperature (CCT) of 2822 K and color rendering index (CRI) of 94 with an efficacy of 94 lumens per watt (LPW) when operating at 4 W input power (steady state) with an overall system efficiency of 81%. At a higher input power of 9 Watts, the lamp provided 658 lumens at 71 LPW.

  8. VALIDATION OF A THERMAL CONDUCTIVITY MEASUREMENT SYSTEM FOR FUEL COMPACTS

    SciTech Connect (OSTI)

    Jeff Phillips; Colby Jensen; Changhu Xing; Heng Ban

    2011-03-01T23:59:59.000Z

    A high temperature guarded-comparative-longitudinal heat flow measurement system has been built to measure the thermal conductivity of a composite nuclear fuel compact. It is a steady-state measurement device designed to operate over a temperature range of 300 K to 1200 K. No existing apparatus is currently available for obtaining the thermal conductivity of the composite fuel in a non-destructive manner due to the compact’s unique geometry and composite nature. The current system design has been adapted from ASTM E 1225. As a way to simplify the design and operation of the system, it uses a unique radiative heat sink to conduct heat away from the sample column. A finite element analysis was performed on the measurement system to analyze the associated error for various operating conditions. Optimal operational conditions have been discovered through this analysis and results are presented. Several materials have been measured by the system and results are presented for stainless steel 304, inconel 625, and 99.95% pure iron covering a range of thermal conductivities of 10 W/m*K to 70 W/m*K. A comparison of the results has been made to data from existing literature.

  9. A Global 86GHz VLBI Survey of Compact Radio Sources

    E-Print Network [OSTI]

    Sang-Sung Lee; Andrei P. Lobanov; Thomas P. Krichbaum; Arno Witzel; J. Anton Zensus; Michael Bremer; Albert Greve; Michael Grewing

    2008-03-28T23:59:59.000Z

    We present results from a large 86GHz global VLBI survey of compact radio sources. The main goal of the survey is to increase by factors of 3--5 the total number of objects accessible for future 3-mm VLBI imaging. The survey observations reach the baseline sensitivity of 0.1Jy and image sensitivity of better than 10 mJy/beam. The total of 127 compact radio sources have been observed. The observations have yielded images for 109 sources, extending the database of the sources imaged at 86GHz with VLBI observation by a factor of 5, and only 6 sources have not been detected. The remaining 12 objects have been detected but could not be imaged due to insufficient closure phase information. Radio galaxies are less compact than quasars and BL Lacs on sub-milliarcsecond scale. Flux densities and sizes of core and jet components of all imaged sources have been estimated using Gaussian model fitting. From these measurements, brightness temperatures have been calculated, taking into account resolution limits of the data. The cores of 70% of the imaged sources are resolved. The core brightness temperatures of the sources peak at $\\sim 10^{11}$ K and only 1% have brightness temperatures higher than $10^{12}$ K. Cores of Intraday Variable (IDV) sources are smaller in angular size than non-IDV sources, and so yield higher brightness temperatures.

  10. The Transition between Star Clusters and Dwarf Galaxies -- On the existence of a mass-radius relation for star clusters of masses >10^7 Mo: are these objects formed in mergers of stellar systems?

    E-Print Network [OSTI]

    Markus Kissler-Patig; Andres Jordan; Nate Bastian

    2005-12-14T23:59:59.000Z

    At which masses does the regime of globular clusters end and the one of dwarf galaxies begin? And what separates these two classes of hot stellar systems? We examine to what extend very massive (>10^7 Mo) young star clusters are similar to their lower mass counter parts and to which degree they resemble other objects in their mass regime (dwarf--globular transition objects (DGTOs), ultra compact dwarf galaxies (UCDs), galaxy nuclei). The comparison is performed by placing the recently observed very massive young clusters onto known scaling relation defined by globular clusters (with typical masses 10^{6.5-7} Mo) young clusters seem to show a mass--radius relation compatible with the one defined by hot stellar systems of galaxy mass. This, in turn, can explain their location on the other scaling relations investigated. It contrasts with the behaviour of the less massive young clusters and of globular clusters, which do not exhibit any mass-radius relation. However, the behaviour of the most massive clusters is similar to that of most other objects in that mass regime (10^6-10^8 Mo). We show that the properties of young massive clusters are compatible with other objects in the same mass regime such as DGTOs/UCDs. They present a possible direct avenue of formation for those objects, which does not require the transformation of a previously existing stellar system. Simulations and observations support the possibility of the formation of such very massive young clusters by early mergers of lower mass stellar clusters, which could explain the emergence of a mass--radius relation.

  11. Stellar hydrodynamical modeling of dwarf galaxies: simulation methodology, tests, and first results

    E-Print Network [OSTI]

    Vorobyov, Eduard I; Hensler, Gerhard

    2015-01-01T23:59:59.000Z

    Cosmological simulations still lack numerical resolution or physical processes to simulate dwarf galaxies in sufficient details. Accurate numerical simulations of individual dwarf galaxies are thus still in demand. We aim at (i) studying in detail the coupling between stars and gas in a galaxy, exploiting the so-called stellar hydrodynamical approach, and (ii) studying the chemo-dynamical evolution of individual galaxies starting from self-consistently calculated initial gas distributions. We present a novel chemo-dynamical code in which the dynamics of gas is computed using the usual hydrodynamics equations, while the dynamics of stars is described by the stellar hydrodynamics approach, which solves for the first three moments of the collisionless Boltzmann equation. The feedback from stellar winds and dying stars is followed in detail. In particular, a novel and detailed approach has been developed to trace the aging of various stellar populations, which enables an accurate calculation of the stellar feedba...

  12. Stellar models with mixing length and T(tau) relations calibrated on 3D convection simulations

    E-Print Network [OSTI]

    Salaris, Maurizio

    2015-01-01T23:59:59.000Z

    (abridged) The calculation of the thermal stratification in the superadiabatic layers of stellar models with convective envelopes is a long standing problem of stellar astrophysics, and has a major impact on predicted observational properties like radius and effective temperature. The Mixing Length Theory, almost universally used to model the superadiabatic convective layers, contains effectively one free parameter to be calibrated --alpha(ml)-- whose value controls the resulting effective temperature. Here we present the first self-consistent stellar evolution models calculated by employing the atmospheric temperature stratification, Rosseland opacities, and calibrated variable alpha(ml) (dependent on effective temperature and surface gravity) from a large suite of three-dimensional radiation hydrodynamics simulations of stellar convective envelopes and atmospheres for solar stellar composition (Trampedach et al. 2013). From our calculations (with the same composition of the radiation hydrodynamics simulatio...

  13. The MODEST questions: challenges and future directions in stellar cluster research

    E-Print Network [OSTI]

    Melvyn B. Davies; Pau Amaro-Seoane; Cees Bassa; Jim Dale; Francesca De Angeli; Marc Freitag; Pavel Kroupa; Dougal Mackey; M. Coleman Miller; Simon Portegies Zwart

    2006-08-30T23:59:59.000Z

    We present a review of some of the current major challenges in stellar cluster research, including young clusters, globular clusters, and galactic nuclei. Topics considered include: primordial mass segregation and runaway mergers, expulsion of gas from clusters, the production of stellar exotica seen in some clusters (eg blue stragglers and extreme horizontal--branch stars), binary populations within clusters, the black--hole population within stellar clusters, the final parsec problem, stellar dynamics around a massive black hole, and stellar collisions. The Modest Questions posed here are the outcome of discussions which took place at the Modest-6A workshop held in Lund, Sweden, in December, 2005. Modest-6A was organised as part of the activities of the Modest Collaboration (see www.manybody.org for further details)

  14. Eclipsing binary systems as tests of low-mass stellar evolution theory

    E-Print Network [OSTI]

    Feiden, Gregory A

    2015-01-01T23:59:59.000Z

    Stellar fundamental properties (masses, radii, effective temperatures) can be extracted from observations of eclipsing binary systems with remarkable precision, often better than 2%. Such precise measurements afford us the opportunity to confront the validity of basic predictions of stellar evolution theory, such as the mass-radius relationship. A brief historical overview of confrontations between stellar models and data from eclipsing binaries is given, highlighting key results and physical insight that have led directly to our present understanding. The current paradigm that standard stellar evolution theory is insufficient to describe the most basic relation, that of a star's mass to its radius, along the main sequence is then described. Departures of theoretical expectations from empirical data, however, provide a rich opportunity to explore various physical solutions, improving our understanding of important stellar astrophysical processes.

  15. Mechanical Feedback: From stellar wind bubbles to starbursts

    E-Print Network [OSTI]

    M. S. Oey; C. J. Clarke; P. Massey

    2001-03-20T23:59:59.000Z

    The current understanding of mechanical feedback is reviewed by evaluating the standard, adiabatic model for shell formation and evolution. This model is relevant to phenomena ranging from individual stellar-wind bubbles to galactic superwinds, forming the basis for our understanding of the multiphase ISM, IGM, and galactic evolutionary processes. Although significant discrepancies between the model and observation have been identified, to date there are none that require a fundamental revision. A variety of evidence, ranging over three orders of magnitude in spatial scale, is broadly consistent with the standard model. This includes kinematics of individual objects, observations of hot gas, the size distribution of HI shells, and outflow rates from starburst galaxies. However, some of the most pressing issues relating to shell evolution are still outstanding and obstruct efforts to resolve key questions like the fate of the hot gas.

  16. Stellar populations in $\\omega$ Centauri: a multivariate analysis

    E-Print Network [OSTI]

    Fraix-Burnet, Didier

    2015-01-01T23:59:59.000Z

    We have performed multivariate statistical analyses of photometric and chemical abundance parameters of three large samples of stars in the globular cluster $\\omega$ Centauri. The statistical analysis of a sample of 735 stars based on seven chemical abundances with the method of Maximum Parsimony (cladistics) yields the most promising results: seven groups are found, distributed along three branches with distinct chemical, spatial and kinematical properties. A progressive chemical evolution can be traced from one group to the next, but also within groups, suggestive of an inhomogeneous chemical enrichment of the initial interstellar matter. The adjustment of stellar evolution models shows that the groups with metallicities [Fe/H]\\textgreater{}-1.5 are Helium-enriched, thus presumably of second generation. The spatial concentration of the groups increases with chemical evolution, except for two groups, which stand out in their other properties as well. The amplitude of rotation decreases with chemical evolutio...

  17. Modular Coils and Plasma Configurations for Quasi-axisymmetric Stellarators

    SciTech Connect (OSTI)

    L.P. Ku and A.H. Boozer

    2010-09-10T23:59:59.000Z

    Characteristics of modular coils for quasi-axisymmetric stellarators that are related to the plasma aspect ratio, number of field periods and rotational transform have been examined systematically. It is observed that, for a given plasma aspect ratio, the coil complexity tends to increase with the increased number of field periods. For a given number of field periods, the toroidal excursion of coil winding is reduced as the plasma aspect ratio is increased. It is also clear that the larger the coil-plasma separation is, the more complex the coils become. It is further demonstrated that it is possible to use other types of coils to complement modular coils to improve both the physics and the modular coil characteristics.

  18. Navy precision optical interferometer measurements of 10 stellar oscillators

    SciTech Connect (OSTI)

    Baines, Ellyn K.; Armstrong, J. Thomas; Schmitt, Henrique R. [Remote Sensing Division, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Benson, James A.; Zavala, R. T. [U.S. Naval Observatory, Flagstaff Station, AZ 86001 (United States); Van Belle, Gerard T., E-mail: ellyn.baines@nrl.navy.mil [Lowell Observatory, Flagstaff, AZ 86001 (United States)

    2014-02-01T23:59:59.000Z

    Using the Navy Precision Optical Interferometer, we measured the angular diameters of 10 stars that have previously measured solar-like oscillations. Our sample covered a range of evolutionary stages but focused on evolved subgiant and giant stars. We combined our angular diameters with Hipparcos parallaxes to determine the stars' physical radii, and used photometry from the literature to calculate their bolometric fluxes, luminosities, and effective temperatures. We then used our results to test the scaling relations used by asteroseismology groups to calculate radii and found good agreement between the radii measured here and the radii predicted by stellar oscillation studies. The precision of the relations is not as well constrained for giant stars as it is for less evolved stars.

  19. A DYNAMICAL SIGNATURE OF MULTIPLE STELLAR POPULATIONS IN 47 TUCANAE

    SciTech Connect (OSTI)

    Richer, Harvey B.; Heyl, Jeremy [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada); Anderson, Jay; Kalirai, Jason S. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Shara, Michael M. [Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States); Dotter, Aaron [Research School of Astronomy and Astrophysics, Australian National University, Weston, ACT 2611 (Australia); Fahlman, Gregory G. [National Research Council, Herzberg Institute of Astrophysics, Victoria, BC V9E 2E7 (Canada); Rich, R. Michael, E-mail: richer@astro.ubc.ca, E-mail: heyl@phas.ubc.ca, E-mail: jayander@stsci.edu, E-mail: jkalarai@stsci.edu, E-mail: mshara@amnh.org, E-mail: aaron.dotter@gmail.com, E-mail: greg.fahlman@nrc-cnrc.gc.ca, E-mail: rmr@astro.ucla.edu [Division of Astronomy and Astrophysics, University of California at Los Angeles, Los Angeles, CA 90095 (United States)

    2013-07-01T23:59:59.000Z

    Based on the width of its main sequence, and an actual observed split when viewed through particular filters, it is widely accepted that 47 Tucanae contains multiple stellar populations. In this contribution, we divide the main sequence of 47 Tuc into four color groups, which presumably represent stars of various chemical compositions. The kinematic properties of each of these groups are explored via proper motions, and a strong signal emerges of differing proper-motion anisotropies with differing main-sequence color; the bluest main-sequence stars exhibit the largest proper-motion anisotropy which becomes undetectable for the reddest stars. In addition, the bluest stars are also the most centrally concentrated. A similar analysis for Small Magellanic Cloud stars, which are located in the background of 47 Tuc on our frames, yields none of the anisotropy exhibited by the 47 Tuc stars. We discuss implications of these results for possible formation scenarios of the various populations.

  20. Microlensing Detections of Planets in Binary Stellar Systems

    E-Print Network [OSTI]

    Dong-Wook Lee; Chung-Uk Lee; Byeong-Gon Park; Sun-Ju Chung; Young-Soo Kim; Ho-Il Kim; Cheongho Han

    2007-09-13T23:59:59.000Z

    We demonstrate that microlensing can be used for detecting planets in binary stellar systems. This is possible because in the geometry of planetary binary systems where the planet orbits one of the binary component and the other binary star is located at a large distance, both planet and secondary companion produce perturbations at a common region around the planet-hosting binary star and thus the signatures of both planet and binary companion can be detected in the light curves of high-magnification lensing events. We find that identifying planets in binary systems is optimized when the secondary is located in a certain range which depends on the type of the planet. The proposed method can detect planets with masses down to one tenth of the Jupiter mass in binaries with separations planet mass and binary separation are not covered by other methods and thus microlensing would be able to make the planetary binary sample richer.

  1. A search for cool subdwarfs: Stellar parameters for 134 candidates

    E-Print Network [OSTI]

    David Yong; David L. Lambert

    2002-09-17T23:59:59.000Z

    The results of a search for cool subdwarfs are presented. Kinematic (U, V, and W) and stellar parameters (Teff, log g, [Fe/H], and V_t) are derived for 134 candidate subdwarfs based on high resolution spectra. The observed stars span 4200K < Teff < 6400K and -2.70 < [Fe/H] < 0.25 including only 8 giants (log g < 4.0). Of the sample, 100 stars have MgH bands present in their spectra. The targets were selected by their large reduced proper-motion, the offset from the solar metallicity main sequence, or culled from the literature. We confirm the claims made by Ryan (1989) regarding the NLTT catalog being a rich source of subdwarfs and verify the success of the reduced proper-motion constraint in identifying metal-poor stars.

  2. Doppler reflectometer system in the stellarator TJ-II

    SciTech Connect (OSTI)

    Happel, T.; Estrada, T.; Blanco, E.; Tribaldos, V.; Cappa, A.; Bustos, A. [Laboratorio Nacional de Fusion, Asociacion Euratom-CIEMAT, 28040 Madrid (Spain)

    2009-07-15T23:59:59.000Z

    A Doppler reflectometer system has recently been installed in the stellarator TJ-II. The system is optimized for the Q-band (33-50 GHz) and the high-curvature plasmas produced in TJ-II. The launch angle of the microwave beam can be controlled by a steerable mirror to obtain angles between {+-}20 deg. enabling the measurement of perpendicular wave numbers in the range of 3-15 cm{sup -1}. The available angular range allows for comparisons between positive and negative values and additionally for calibration of the system. Localization and k{sub perpendicular}-estimation is done via the three-dimensional ray/beam-tracing code TRUBA. First measured spectra and radial profiles of the perpendicular velocity of plasma density fluctuations are presented.

  3. The Solar Heavy Element Abundances: I. Constraints from Stellar Interiors

    E-Print Network [OSTI]

    Delahaye, F; Delahaye, Franck; Pinsonneault, Marc

    2005-01-01T23:59:59.000Z

    The latest solar atmosphere models include non-LTE corrections and 3D hydrodynamic convection simulations. These models predict a significant reduction in the solar metal abundance, which leads to a serious conflict between helioseismic data and the predictions of solar interiors models. We demonstrate that the helioseismic constraints on the surface convection zone depth and helium abundance combined with stellar interiors models can be used to define the goodness of fit for a given chemical composition. After a detailed examination of the errors in the theoretical models we conclude that models constructed with the older solar abundances are consistent (seismic data. Models constructed with the proposed new low abundance scale are strongly disfavored, disagreeing at the 15 \\sigma level. We then use the sensitivity of the seismic properties to abundance changes to invert the problem and infer a seismic solar heavy element abundance mix with two components: meteoritic abundances, and th...

  4. Carbon-poor stellar cores as supernova progenitors

    E-Print Network [OSTI]

    Roni Waldman; Zalman Barkat

    2007-04-16T23:59:59.000Z

    Exploring stellar models which ignite carbon off-center (in the mass range of about 1.05 - 1.25 Msun, depending on the carbon mass fraction) we find that they may present an interesting SN I progenitor scenario, since whereas in the standard scenario runaway always takes place at the same density of about 2 X 10^9 gr/cm^3, in our case, due to the small amount of carbon ignited, we get a whole range of densities from 1 X 10^9 up to 6 X 10^9 gr/cm^3. These results could contribute in resolving the emerging recognition that at least some diversity among SNe I exists, since runaway at various central densities is expected to yield various outcomes in terms of the velocities and composition of the ejecta, which should be modeled and compared to observations.

  5. Confinement of pure electron plasmas in the CNT stellarator

    SciTech Connect (OSTI)

    Pedersen, T. Sunn; Berkery, J. W.; Boozer, A. H.; Brenner, P. W.; Hahn, M.; Durand de Gevigney, B.; Martin, X. Sarasola [Columbia University, New York, NY 10027 (United States); Marksteiner, Q. R. [Columbia University, New York, NY 10027 (United States); Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2009-03-30T23:59:59.000Z

    The Columbia Non-neutral Torus is a stellarator devoted to non-neutral and electron-positron plasma research. Confinement and transport processes have been studied in some detail now, and an understanding of these processes has emerged. Transport is driven in two ways: The presence of internal rods, and the presence of neutrals. Both transport processes are clearly distinguished experimentally, and a model of the rod driven transport has been developed, yielding very good agreement with experimental data. The neutral driven transport is faster than originally expected and indicates the presence of unconfined orbits in CNT. Numerical modeling of the electron orbits in CNT confirms the existence of loss orbits and shows that a flux surface conforming electrostatic boundary will greatly improve confinement. Such a boundary has now been installed in CNT, with initial results showing an order of magnitude improvement in confinement.

  6. Influence of Stellar Multiplicity On Planet Formation. III. Adaptive Optics Imaging of Kepler Stars With Gas Giant Planets

    E-Print Network [OSTI]

    Wang, Ji; Horch, Elliott P; Xie, Ji-Wei

    2015-01-01T23:59:59.000Z

    As hundreds of gas giant planets have been discovered, we study how these planets form and evolve in different stellar environments, specifically in multiple stellar systems. In such systems, stellar companions may have a profound influence on gas giant planet formation and evolution via several dynamical effects such as truncation and perturbation. We select 84 Kepler Objects of Interest (KOIs) with gas giant planet candidates. We obtain high-angular resolution images using telescopes with adaptive optics (AO) systems. Together with the AO data, we use archival radial velocity data and dynamical analysis to constrain the presence of stellar companions. We detect 59 stellar companions around 40 KOIs for which we develop methods of testing their physical association. These methods are based on color information and galactic stellar population statistics. We find evidence of suppressive planet formation within 20 AU by comparing stellar multiplicity. The stellar multiplicity rate for planet host stars is 0$^{+5...

  7. MID-INFRARED SPECTRAL VARIABILITY ATLAS OF YOUNG STELLAR OBJECTS

    SciTech Connect (OSTI)

    Kospal, A. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA, Leiden (Netherlands); Abraham, P.; Kun, M.; Moor, A. [Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, P.O. Box 67, 1525 Budapest (Hungary); Acosta-Pulido, J. A. [Instituto de Astrofisica de Canarias, Via Lactea s/n, 38200 La Laguna, Tenerife (Spain); Dullemond, C. P. [Institut fuer Theoretische Astrophysik, Zentrum fuer Astronomie der Universitaet Heidelberg, Albert-Ueberle-Str. 2, 69120 Heidelberg (Germany); Henning, Th.; Leinert, Ch. [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany); Turner, N. J., E-mail: akospal@rssd.esa.int [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2012-08-01T23:59:59.000Z

    Optical and near-infrared variability is a well-known property of young stellar objects. However, a growing number of recent studies claim that a considerable fraction of them also exhibit mid-infrared flux changes. With the aim of studying and interpreting variability on a decadal timescale, here we present a mid-infrared spectral atlas containing observations of 68 low- and intermediate-mass young stellar objects. The atlas consists of 2.5-11.6 {mu}m low-resolution spectra obtained with the ISOPHOT-S instrument on board the Infrared Space Observatory (ISO) between 1996 and 1998, as well as 5.2-14.5 {mu}m low-resolution spectra obtained with the Infrared Spectrograph instrument on board the Spitzer Space Telescope between 2004 and 2007. The observations were retrieved from the ISO and Spitzer archives and were post-processed interactively by our own routines. For those 47 objects where multi-epoch spectra were available, we analyze mid-infrared spectral variability on annual and/or decadal timescales. We identify 37 variable candidate sources. Many stars show wavelength-independent flux changes, possibly due to variable accretion rates. In several systems, all exhibiting 10 {mu}m silicate emission, the variability of the 6-8 {mu}m continuum, and the silicate feature exhibit different amplitudes. A possible explanation is variable shadowing of the silicate-emitting region by an inner disk structure of changing height or extra silicate emission from dust clouds in the disk atmosphere. Our results suggest that mid-infrared variability, in particular, the wavelength-dependent changes, is more ubiquitous than was known before. Interpreting this variability is a new possibility for exploring the structure of the disk and its dynamical processes.

  8. National Renewable Energy Laboratory

    E-Print Network [OSTI]

    National Renewable Energy Laboratory Innovation for Our Energy Future ponsorship Format Reversed Color:White rtical Format Reversed-A ertical Format Reversed-B National Renewable Energy Laboratory National Renewable Energy Laboratory Innovation for Our Energy Future National Renewable Energy Laboratory

  9. Sandia National Laboratories: Sandia National Laboratories

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

    in Hosted by Sandia National Laboratories and the Electric Power Research Institute (EPRI) Inverter reliability drives project life cycle costs and plant performance. This...

  10. Sandia National Laboratories: National Rotor Testbed Functional...

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

    of the National Rotor Testbed: An Aeroelastically Relevant Research-Scale Wind Turbine Rotor." Approximately 60 researchers from various institutions and countries attended...

  11. Consent Order, Lawrence Livermore National National Security...

    Energy Savers [EERE]

    for deficiencies associated with the Lawrence Livermore National Laboratory Chronic Beryllium Disease Prevention Program On October 29, 2010, the U.S. Department of Energy (DOE)...

  12. Sandia National Laboratories: Jawaharlal Nehru Solar National...

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

    Jawaharlal Nehru Solar National Solar Energy Mission Solar Energy Research Institute for India and the United States Kick-Off On November 27, 2012, in Concentrating Solar Power,...

  13. National Security Photo Gallery | Argonne National Laboratory

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

    National Security Photo Gallery Richard Cirillo 1 of 10 Richard Cirillo RICHARD R. CIRILLO Dr. Richard R. Cirillo serves as Director of the Decision and Information Sciences...

  14. Sandia National Laboratories: national reliability database

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

    national reliability database Third Annual Continuous Reliability Enhancement for Wind (CREW) Database Report Now Available On October 17, 2013, in Energy, News, News & Events,...

  15. Argonne National Laboratory | Argonne National Laboratory

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

    Argonne National Laboratory Slip sliding away Graphene and diamonds prove a slippery combination Read More ACT-SO winners Argonne mentors students for the next generation of...

  16. A Leadership-Class U.S. Domestic Stellarator Program Hutch Neilson, David Gates, and Michael Zarnstorff

    E-Print Network [OSTI]

    A Leadership-Class U.S. Domestic Stellarator Program Hutch Neilson, David Gates, and Michael concepts or because they lack the core capabilities for it. U.S. leadership in QS stellarators is both.S. leadership in stellarators requires a domestic program to pursue U.S. innovations targeted to materially

  17. The Hazards of Use and Disposal of Compact Fluorescent Bulbs Compact fluorescent lights (aka. CFLs) work by exciting a phosphorous coating within the tube to emit

    E-Print Network [OSTI]

    Maroncelli, Mark

    The Hazards of Use and Disposal of Compact Fluorescent Bulbs Compact fluorescent lights (aka. CFLs the bulb to be an efficient light source. By comparison, older home thermometers contain 500 milligrams decade. HOW SHOULD I DISPOSE OF CFL'S? The presence of mercury requires that all CFL bulbs are properly

  18. Congressional Delegation visits Naval Reactors Facility | National Nuclear

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625govInstrumentstdmadapInactiveVisiting theCommercialization andComputerConfirmed: Stellar Behemoth

  19. Preliminary results of post-irradiation examination of the AGR-1 TRISO fuel compacts

    SciTech Connect (OSTI)

    Paul Demkowicz; John Hunn; Robert Morris; Jason Harp; Philip Winston; Charles Baldwin; Fred Montgomery; Scott Ploger; Isabella van Rooyen

    2012-10-01T23:59:59.000Z

    Five irradiated fuel compacts from the AGR-1 experiment have been examined in detail in order to assess in-pile fission product release behavior. Compacts were electrolytically deconsolidated and analyzed using the leach-burn-leach technique to measure fission product inventory in the compact matrix and identify any particles with a defective SiC layer. Loose particles were then gamma counted to measure the fission product inventory. One particle with a defective SiC layer was found in the five compacts examined. The fractional release of Ag 110m from the particles was significant. The total fraction of silver released from all the particles within a compact ranged from 0-0.63 and individual particles within a single compact often exhibited a very wide range of silver release. The average fractional release of Eu-154 from all particles in a compact was 2.4×10-4—1.3×10-2, which is indicative of release through intact coatings. The fractional Cs-134 inventory in the compact matrix was <2×10-5 when all coatings remained intact, indicating good cesium retention. Approximately 1% of the palladium inventory was found in the compact matrix for two of the compacts, indicating significant release through intact coatings.

  20. The impact of alpha/Fe enhanced stellar evolutionary tracks on the ages of elliptical galaxies

    E-Print Network [OSTI]

    Daniel Thomas; Claudia Maraston

    2003-02-04T23:59:59.000Z

    We complement our study of alpha/Fe enhanced stellar population models of Lick absorption indices (Thomas et al. 2003) by comparing two sets of alpha/Fe enhanced models. In both models the impact on Lick indices due to alpha/Fe enhancement is accounted for through a modification of the stellar absorption line-strengths using the response functions of Tripicco & Bell (1995). One set of models, however, uses solar-scaled, the other alpha/Fe enhanced stellar evolutionary tracks. Since the alpha/Fe enhanced tracks are hotter than the solar-scaled ones (Salasnich et al. 2000), the correspondent stellar population models have slightly weaker metallic indices (i.e. Mgb, etc.) and stronger Balmer line indices (Hbeta) (Maraston et al 2003). Here we explore quantitatively the impact of this effect on the alpha/Fe ratios, metallicities and ages that are derived for elliptical galaxies. We find that the modest decrease of the metallic indices Mgb and balance each other, such that fully consistent alpha/Fe ratios are derived for stellar systems using alpha/Fe enhanced models with either solar-scaled or alpha/Fe enhanced stellar tracks. The decrease of the metallic indices and the increase of Hbeta conspire in a way that also consistent metallicities are obtained. The derived ages, instead, are significantly different. The inclusion of alpha/Fe enhanced stellar tracks leads to the derivation of ages as high as 30 Gyr for elliptical galaxies. For the same objects, ages not older than 15 Gyr are obtained, if alpha/Fe enhanced models using solar-scaled tracks are adopted. This may indicate that current stellar evolutionary models overestimate the bluing of stellar evolutionary tracks due to alpha/Fe enhanced chemical mixtures at super-solar metallicities.