National Library of Energy BETA

Sample records for national compact stellarator

  1. National Compact Stellarator Experiment Project Closeout Report PROJECT CLOSEOUT REPORT

    E-Print Network [OSTI]

    Princeton Plasma Physics Laboratory

    Approved by Jeffrey Makiel DOE Federal Project Director for the National Compact Stellarator Experiment II.....................................................................................1 3. PROJECT HISTORY

  2. Risk Management on the National Compact Stellarator Project (NCSX)

    SciTech Connect (OSTI)

    Risk Management on the National Compact Stellarator Project (NCSX)

    2009-02-06

    In its simplest form, risk management is a continuous assessment from project start to completion that identifies what can impact your project (i.e., what the risks are)., which of these risks are important, and identification and implementation of strategies to deal with these risks (both threats and opportunities). The National Compact Stellerator Experiment (NCSX) Project was a "first-of-a-kind" fusion experiment that was technically very challenging, primarily resulting from the complex component geometries and tight tolerances. Initial risk quantification approaches proved inadequate and contributed to the escalation of costs as the design evolved and construction started. After the Project was well into construction, a new risk management plan was adopted. This plan was based on successful Department of Energy (DOE) and industrial risk management precepts. This paper will address the importance of effective risk management processes and lessons learned. It is of note that a steady reduction of risk was observed in the last six months of the project.

  3. Alfven Continuum and Alfven Eigenmodes in the National Compact Stellarator Experiment

    SciTech Connect (OSTI)

    Fesenyuk, O. P.; Kolesnichenko, Ya. I.; Lutsenko, V. V.; White, R. B.; Yakovenko, Yu. V.

    2004-09-17

    The Alfven continuum (AC) in the National Compact Stellarator Experiment (NCSX) is investigated with the AC code COBRA. The resonant interaction of Alfven eigenmodes and the fast ions produced by neutral beam injection is analyzed. Alfven eigenmodes residing in one of the widest gaps of the NCSX AC, the ellipticity-induced gap, are studied with the code BOA-E.

  4. Neutral Beam Injection Requirements and Design Issues for the National Compact Stellarator Experiment

    SciTech Connect (OSTI)

    H.W. Kugel; H. Neilson; W. Reiersen; M. Zarnstorff

    2002-02-11

    The National Compact Stellarator Experiment (NCSX) will require 6 MW of 50 keV neutral beam injection (NBI) with initial pulse lengths of 500 msec and upgradeable to pulse lengths of 1.5 sec. This paper discusses the NCSX NBI requirements and design issues, and shows how these are provided by the candidate PBX-M [Princeton Beta Experiment-Modification] NBI system.

  5. Comparing linear microinstability of the National Compact Stellarator Experiment and a shaped tokamak

    E-Print Network [OSTI]

    Baumgaertel, J A; Mikkelsen, D R

    2012-01-01

    One metric for comparing confinement properties of different magnetic fusion energy configurations is the linear critical gradient of drift wave modes. The critical gradient scale length determines the ratio of the core to pedestal temperature when a plasma is limited to marginal stability in the plasma core. The gyrokinetic turbulence code GS2 was used to calculate critical temperature gradients for the linear, collisionless ion temperature gradient (ITG) mode in the National Compact Stellarator Experiment (NCSX) and a prototypical shaped tokamak, based on the profiles of a JET H-mode shot and the stronger shaping of ARIES-AT. While a concern was that the narrow cross section of NCSX at some toroidal locations would result in steep gradients that drive instabilities more easily, it is found that other stabilizing effects of the stellarator configuration offset this so that the normalized critical gradients for NCSX are competitive with or even better than for the tokamak. For the adiabatic ITG mode, NCSX and...

  6. Comparing Linear Microinstability of the National Compact Stellarator Expriment and a Shaped Tokamak

    SciTech Connect (OSTI)

    J.A. Baumgaertel, G.W. Hammett and D.R. Mikkelsen

    2012-11-20

    One metric for comparing con nement properties of di erent magnetic fusion energy con gurations is the linear critical gradient of drift wave modes. The critical gradient scale length determines the ratio of the core to pedestal temperature when a plasma is limited to marginal stability in the plasma core. The gyrokinetic turbulence code GS2 was used to calculate critical temperature gradients for the linear, collisionless ion tem- perature gradient (ITG) mode in the National Compact Stellarator Experiment (NCSX) and a prototypical shaped tokamak, based on the pro les of a JET H-mode shot and the stronger shaping of ARIES-AT. While a concern was that the narrow cross section of NCSX at some toroidal locations would result in steep gradients that drive instabilities more easily, it is found that other stabilizing e ects of the stellarator con guration o set this so that the normalized critical gradients for NCSX are competitive with or even better than for the tokamak. For the adiabatic ITG mode, NCSX and the tokamak had similar critical gradients, though beyond marginal stability, NCSX had larger growth rates. However, for the kinetic ITG mode, NCSX had a higher critical gradient and lower growth rates until a/LT ?#25; 1:5 a/LT;crit, when it surpassed the tokamak's. A discussion of the results presented with respect to a/LT vs R/LT is included.

  7. Results of Compact Stellarator Engineering Trade Studies

    SciTech Connect (OSTI)

    Tom Brown, L. Bromberg, M. Cole

    2009-05-27

    number of technical requirements and performance criteria can drive stellarator costs, e.g., tight tolerances, accurate coil positioning, low aspect ratio (compactness), choice of assembly strategy, metrology, and complexity of the stellarator coil geometry. With the completion of a seven-year design and construction effort of the National Compact Stellarator Experiment (NCSX) it is useful to interject the NCSX experience along with the collective experiences of the NCSX stellarator community to improving the stellarator configuration. Can improvements in maintenance be achieved by altering the stellarator magnet configuration with changes in the coil shape or with the combination of trim coils? Can a mechanical configuration be identified that incorporates a partial set of shaped fixed stellarator coils along with some removable coil set to enhance the overall machine maintenance? Are there other approaches that will simplify the concepts, improve access for maintenance, reduce overall cost and improve the reliability of a stellarator based power plant? Using ARIES-CS and NCSX as reference cases, alternative approaches have been studied and developed to show how these modifications would favorably impact the stellarator power plant and experimental projects. The current status of the alternate stellarator configurations being developed will be described and a comparison made to the recently designed and partially built NCSX device and the ARIES-CS reactor design study.

  8. Results of Compact Stellarator Eengineering Trade Studies

    SciTech Connect (OSTI)

    T. Brown, L. Bromberg, and M. Cole

    2009-09-25

    A number of technical requirements and performance criteria can drive stellarator costs, e.g., tight tolerances, accurate coil positioning, low aspect ratio (compactness), choice of assembly strategy, metrology, and complexity of the stellarator coil geometry. With the completion of a seven-year design and construction effort of the National Compact Stellarator Experiment (NCSX) it is useful to interject the NCSX experience along with the collective experiences of the NCSX stellarator community to improving the stellarator configuration. Can improvements in maintenance be achieved by altering the stellarator magnet configuration with changes in the coil shape or with the combination of trim coils? Can a mechanical configuration be identified that incorporates a partial set of shaped fixed stellarator coils along with some removable coil set to enhance the overall machine maintenance? Are there other approaches that will simplify the concepts, improve access for maintenance, reduce overall cost and improve the reliability of a stellarator based power plant? Using ARIES-CS and NCSX as reference cases, alternative approaches have been studied and developed to show how these modifications would favorably impact the stellarator power plant and experimental projects. The current status of the alternate stellarator configurations being developed will be described and a comparison made to the recently designed and partially built NCSX device and the ARIES-CS reactor design study.

  9. Physics of compact stellarators* S. P. Hirshman,

    E-Print Network [OSTI]

    , derives from both the desire to de- sign a fusion reactor of economical size and to combine the favorable at exploring the physics of compact stellarators. For compact stellarators to be reactor relevant, the plasmaPhysics of compact stellarators* S. P. Hirshman, D. A. Spong, J. C. Whitson, B. Nelson, D. B

  10. 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)

    2012-12-15

    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.

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

    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)

    2013-02-15

    One metric for comparing confinement properties of different magnetic fusion energy configurations is the linear critical gradient of drift wave modes. The critical gradient scale length determines the ratio of the core to pedestal temperature when a plasma is limited to marginal stability in the plasma core. The gyrokinetic turbulence code GS2 was used to calculate critical temperature gradients for the linear, collisionless ion temperature gradient (ITG) mode in the National Compact Stellarator Experiment (NCSX) and a prototypical shaped tokamak, based on the profiles of a JET H-mode shot and the stronger shaping of ARIES-AT. While a concern was that the narrow cross section of NCSX at some toroidal locations would result in steep gradients that drive instabilities more easily, it is found that other stabilizing effects of the stellarator configuration offset this so that the normalized critical gradients for NCSX are competitive with or even better than for the tokamak. For the adiabatic ITG mode, NCSX and the tokamak had similar adiabatic ITG mode critical gradients, although beyond marginal stability, NCSX had larger growth rates. However, for the kinetic ITG mode, NCSX had a higher critical gradient and lower growth rates until a/L{sub T} Almost-Equal-To 1.5 a/L{sub T,crit}, when it surpassed the tokamak's. A discussion of the results presented with respect to a/L{sub T} vs. R/L{sub T} is included.

  12. Environmental Assessment and Finding of No Significant Impact: The National Compact Stellarator Experiment at the Princeton Plasma Physics Laboratory

    SciTech Connect (OSTI)

    N /A

    2002-10-25

    If the United States is to meet the energy needs of the future, it is essential that new technologies emerge to compensate for dwindling supplies of fossil fuels, the eventual depletion of fissionable uranium used in present-day nuclear reactors, and the limitations of solar, hydro and wind alternatives. Fusion energy, the power source of the sun and other stars, has the potential to become a major source of energy for the future. Power from fusion would provide substantially reduced environmental impacts as compared with current forms of energy generation. Thus, the United States and other countries around the world continue to pursue development of fusion energy as one of a number of potential power sources for the long term. Fusion research, using various machine configurations, has been proceeding since the early 1950's, and significant progress has been achieved in performance and in understanding of the underlying physics. For most of this period, fusion machines called stellarators and tokamaks, which are toroidal (doughnut-shaped) devices, have been most frequently used to conduct experiments for producing controlled nuclear fusion. It is now desirable to take a next step in the fusion development program, by providing an experimental device to investigate the attractiveness of a compact stellarator as the basis for a fusion power reactor. This concept has the potential to build upon advances in understanding of stellarators and tokamaks, and to combine the best features of both. The goal is to build a compact stellarator that would be smaller than conventional stellarators and operate more efficiently than previous tokamaks. Such a device would broaden our understanding of magnetic fusion science while contributing to the development of a potentially attractive fusion reactor solution that may have cost advantages over other fusion concepts.

  13. THE ARIES-CS COMPACT STELLARATOR FUSION POWER PLANT

    E-Print Network [OSTI]

    Najmabadi, Farrokh

    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

  14. A Compact Quasi-axisymmetric Stellarator Reactor

    SciTech Connect (OSTI)

    L.P. Ku; the ARIES-CS Team

    2003-10-20

    We report the progress made in assessing the potential of compact, quasi-axisymmetric stellarators as power-producing reactors. Using an aspect ratio A=4.5 configuration derived from NCSX and optimized with respect to the quasi-axisymmetry and MHD stability in the linear regime as an example, we show that a reactor of 1 GW(e) maybe realizable with a major radius *8 m. This is significantly smaller than the designs of stellarator reactors attempted before. We further show the design of modular coils and discuss the optimization of coil aspect ratios in order to accommodate the blanket for tritium breeding and radiation shielding for coil protection. In addition, we discuss the effects of coil aspect ratio on the peak magnetic field in the coils.

  15. Localized Ballooning Modes in Compact Quasiaxially Symmetric Stellarators

    SciTech Connect (OSTI)

    M.H. Redi; J. Canik; R.L. Dewar; E.D. Fredrickson; W.A. Cooper; J.L. Johnson; S. Klasky

    2001-06-14

    Understanding of ballooning mode stability boundaries may lead to performance improvement of toroidal devices through control of plasma disruptions. Toroidally localized ballooning modes have been found as precursors to high-beta plasma disruptions on the Tokamak Fusion Test Reactor (TFTR) arising in conditions of n=1 kink mode asymmetry. Recent optimization has shown that magnetohydrodynamic (MHD) stability as well as good particle confinement are likely to be achievable in the National Compact Stellarator Experiment (NCSX), a compact, quasiaxially symmetric stellarator (QAS) for values of the plasma near beta = 4%. The configuration, with a major radius of 1.42 m, an aspect ratio of 4.4, a toroidal magnetic field 1.2-1.7 T and 6 MW of neutral-beam heating, is stable to MHD instabilities, and is expected to be limited by high-n kink and ballooning modes. This paper describes the ballooning eigenvalue isosurfaces for NCSX, the first step in an examination of the kinetic stabilization of the ballooning beta limit using a hybrid WKB approach.

  16. Energetic particle transport in compact quasiaxisymmetric stellarators

    E-Print Network [OSTI]

    simulations of alpha particle orbits in a reactor sized QAS which is predicted to have good partic and Garabedian 2 in addition to experiments at WVII­AS 3 indicate remarkably good stability and transport, driven by plasma current in tokamaks. Stellarators are characterized by good particle confinement as long

  17. 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)

    2014-03-01

    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.

  18. Compact stellar systems in the Fornax cluster: a UV perspective

    E-Print Network [OSTI]

    Steffen Mieske; Michael Hilker; Dominik J. Bomans; Soo-Chang Rey; Suk Kim; Suk-Jin Yoon; Chul Chung

    2008-08-01

    In recent years, increasing evidence for chemical complexity and multiple stellar populations in massive globular clusters (GCs) has emerged, including extreme horizontal branches (EHBs) and UV excess. Our goal is to improve our understanding of UV excess in the regime of both massive GCs and ultra-compact dwarf galaxies (UCDs). To this end, we use deep archival GALEX data of the central Fornax cluster to measure NUV and FUV magnitudes of UCDs and massive GCs. We obtain NUV photometry for a sample of 35 compact objects with -13.5stellar population models, even for models with enhanced Helium abundance. This suggests that not only He-enrichment has contributed to forming the EHB population of these GCs. The GCs extend to stronger UV excess than GCs in M31 and massive GCs in M87, at the 97% confidence level. Most of the UCDs with FUV photometry also show evidence for UV excess, but their UV colours can be matched by isochrones with enhanced Helium abundances and old ages 12-14 Gyrs. We find that Fornax compact objects with X-ray emission detected from Chandra images are almost disjunct in colour from compact objects with GALEX UV detection, with only one X-ray source among the 35 compact objects. However, since this source is one of the three most UV bright GCs, we cannot exclude that the physical processes causing X-ray emission also contribute to some of the observed UV excess.

  19. Energetic particle transport in compact quasi-axisymmetric stellarators

    E-Print Network [OSTI]

    in tokamaks. Stellarators are characterized by good particle confinement as long as the magnetic field size and magnetic field geometry. PACS numbers 52.20.Dq, 52.55.Hc,52.65.Cc,52.65.-y #12;2 I. INTRODUCTION The multi-national, decades-long search for a toroidal magnetic system which will confine stable

  20. Initial Activation Assessment for ARIES Compact Stellarator Power Plant

    SciTech Connect (OSTI)

    El-Guebaly, L.; Wilson, P.; Paige, D. [University of Wisconsin, Fusion Technology Institute (United States)] (and others)

    2005-04-15

    As the safety assessment frequently requires knowledge of the activation parameters, we estimated the highest possible activity, decay heat, and waste disposal rating on the time scale after shutdown for the compact stellarator power plant ARIES-CS. We selected two widely different systems employing SiC/SiC composites and low-activation ferritic steel (FS) as structural materials. Our results show that components of both systems qualify as Class C low-level waste (LLW) at the end of a 100 y storage period following the decommissioning of the plant. The SiC blanket, vacuum vessel, and magnet offer very low waste disposal rating to the extent that a Class A LLW seems achievable for these components. On this last point, we discussed the split between the Class A and Class C wastes, emphasizing our motivation to lower the level of ARIES-CS radioactive waste.

  1. 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

  2. MAINTENANCE APPROACHES FOR ARIES-CS COMPACT STELLARATOR POWER CORE , S. Malang2

    E-Print Network [OSTI]

    during maintenance operations and to determine the maximum size of the blanket replacement units. IMAINTENANCE APPROACHES FOR ARIES-CS COMPACT STELLARATOR POWER CORE X.R. Wang1 , S. Malang2 , A maintenance approaches envisaged for the Compact Stellarator (CS) power core have been identified

  3. Ballooning Stability of the Compact Quasiaxially Symmetric Stellarator

    SciTech Connect (OSTI)

    M.H. Redi; J. Canik; R.L. Dewar; J.L. Johnson; S. Klasky; W.A. Cooper; W. Kerbichler

    2001-09-19

    The magnetohydrodynamic (MHD) ballooning stability of a compact, quasiaxially symmetric stellarator (QAS), expected to achieve good stability and particle confinement is examined with a method that can lead to estimates of global stability. Making use of fully 3D, ideal-MHD stability codes, the QAS beta is predicted to be limited above 4% by ballooning and high-n kink modes. Here MHD stability is analyzed through the calculation and examination of the ballooning mode eigenvalue isosurfaces in the 3-space [s, alpha, theta(subscript ''k'')]; s is the edge normalized toroidal flux, alpha is the field line variable, and theta(subscript ''k'') is the perpendicular wave vector or ballooning parameter. Broken symmetry, i.e., deviations from axisymmetry, in the stellarator magnetic field geometry causes localization of the ballooning mode eigenfunction, with new types of nonsymmetric, eigenvalue isosurfaces in both the stable and unstable spectrum. The isosurfaces around the most unstable points i n parameter space (well above marginal) are topologically spherical. In such cases, attempts to use ray tracing to construct global ballooning modes lead to a k-space runaway. Introduction of a reflecting cutoff in k(perpendicular) to model numerical truncation or finite Larmor radius (FLR) yields chaotic ray paths ergodically filling the allowed phase space, indicating that the global spectrum must be described using the language of quantum chaos theory. However, the isosurface for marginal stability in the cases studied are found to have a more complex topology, making estimation of FLR stabilization more difficult.

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

    E-Print Network [OSTI]

    Raffray, A. René

    1 FT/P3-13 Compact Stellarator Power Plants ­ Prospects, Technical Issue, and R&D Directions F was to investigate whether stellarator power plants can be made to be similar in size to advanced tokamak variants features as a power plant because of the lack of a large driven external current: they are inherently

  5. 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)

    2008-10-15

    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}.

  6. 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

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

    E-Print Network [OSTI]

    Najmabadi, Farrokh

    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

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

    E-Print Network [OSTI]

    Najmabadi, Farrokh

    2006-01-01

    Fusion Engineering and Design 81 (2006) 2679­2693 Recent progress in the ARIES compact stellarator represents a large number of trade-offs among physics parameters and engineering constraints. As such of physics and engineering options, requirements, and constraints. In the second phase, we explored

  9. 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

  10. Compact object mergers: Observations of supermassive binary black holes and stellar tidal disruption events

    E-Print Network [OSTI]

    Komossa, S

    2015-01-01

    The capture and disruption of stars by supermassive black holes (SMBHs), and the formation and coalescence of binaries, are inevitable consequences of the presence of SMBHs at the cores of galaxies. Pairs of active galactic nuclei (AGN) and binary SMBHs are important stages in the evolution of galaxy mergers, and an intense search for these systems is currently ongoing. In the early and advanced stages of galaxy merging, observations of the triggering of accretion onto one or both BHs inform us about feedback processes and BH growth. Identification of the compact binary SMBHs at parsec and sub-parsec scales provides us with important constraints on the interaction processes that govern the shrinkage of the binary beyond the "final parsec". Coalescing binary SMBHs are among the most powerful sources of gravitational waves (GWs) in the universe. Stellar tidal disruption events (TDEs) appear as luminous, transient, accretion flares when part of the stellar material is accreted by the SMBH. About 30 events have b...

  11. National Compact Stellarator Experiment COST AND SCHEDULE ESTIMATING GUIDE

    E-Print Network [OSTI]

    Princeton Plasma Physics Laboratory

    ......................................................................................... 2 2.2.3.1 Labor................................................................. 6 3.3.1.1 Step 1 ­ Technical, Cost and Risk Factor Determination....................... 6 3

  12. Anderson Localization of Ballooning Modes, Quantum Chaos and the Stability of Compact Quasiaxially Symmetric Stellarators

    SciTech Connect (OSTI)

    M.H. Redi; J.L. Johnson; S. Klasky; J. Canik; R.L. Dewar; W.A. Cooper

    2001-10-31

    The radially local magnetohydrodynamic (MHD) ballooning stability of a compact, quasiaxially symmetric stellarator (QAS), is examined just above the ballooning beta limit with a method that can lead to estimates of global stability. Here MHD stability is analyzed through the calculation and examination of the ballooning mode eigenvalue isosurfaces in the 3-space [s, alpha, theta(subscript ''k'')]; s is the edge normalized toroidal flux, alpha is the field line variable, and q(subscript ''k'') is the perpendicular wave vector or ballooning parameter. Broken symmetry, i.e., deviations from axisymmetry, in the stellarator magnetic field geometry causes localization of the ballooning mode eigenfunction, and gives rise to new types of nonsymmetric eigenvalue isosurfaces in both the stable and unstable spectrum. For eigenvalues far above the marginal point, isosurfaces are topologically spherical, indicative of strong ''quantum chaos.'' The complexity of QAS marginal isosurfaces suggests that finite Larmor radius stabilization estimates will be difficult and that fully three-dimensional, high-n MHD computations are required to predict the beta limit.

  13. A Stellar Population Gradient in VII Zw 403 - Implications for the Formation of Blue Compact Dwarf Galaxies

    E-Print Network [OSTI]

    Regina E. Schulte-Ladbeck; Ulrich Hopp; Mary M. Crone; Laura Greggio

    1999-05-09

    We present evidence for the existence of an old stellar halo in the Blue Compact Dwarf galaxy VII Zw 403. VII Zw 403 is the first Blue Compact Dwarf galaxy for which a clear spatial segregation of the resolved stellar content into a "core-halo" structure is detected. Multicolor HST/WFPC2 observations indicate that active star formation occurs in the central region, but is strikingly absent at large radii. Instead, a globular-cluster-like red giant branch suggests the presence of an old (> 10 Gyr) and metal poor (=-1.92) stellar population in the halo. While the vast majority of Blue Compact Dwarf galaxies has been recognized to possess halos of red color in ground-based surface photometry, our observations of VII Zw 403 establish for the first time a direct correspondence between a red halo color and the presence of old, red giant stars. If the halos of Blue Compact Dwarf galaxies are all home to such ancient stellar populations, then the fossil record conflicts with delayed-formation scenarios for dwarfs.

  14. How elevated is the dynamical-to-stellar mass ratio of the ultra-compact dwarf S999?

    E-Print Network [OSTI]

    Janz, Joachim; Norris, Mark A; Strader, Jay; Penny, Samantha J; Fagioli, Martina; Romanowsky, Aaron J

    2015-01-01

    Here we present new Keck ESI high-resolution spectroscopy and deep archival HST/ACS imaging for S999, an ultra-compact dwarf in the vicinity of M87, which was claimed to have an extremely high dynamical-to-stellar mass ratio. Our data increase the total integration times by a factor of 5 and 60 for spectroscopy and imaging, respectively. This allows us to constrain the stellar population parameters for the first time (simple stellar population equivalent age $=7.6^{+2.0}_{-1.6}$ Gyr; $[Z/\\textrm{H}]=-0.95^{+0.12}_{-0.10}$; $[\\alpha/\\textrm{Fe}]=0.34^{+0.10}_{-0.12}$). Assuming a Kroupa stellar initial mass function, the stellar population parameters and luminosity ($M_{F814W}=-12.13\\pm0.06$ mag) yield a stellar mass of $M_*=3.9^{+0.9}_{-0.6}\\times10^6 M_{\\odot}$, which we also find to be consistent with near-infrared data. Via mass modelling, with our new measurements of velocity dispersion ($\\sigma_{ap}=27\\pm2$ km s$^{-1}$) and size ($R_e=20.9\\pm1.0$ pc), we obtain an elevated dynamical-to-stellar mass ratio...

  15. Anderson localization of ballooning modes, quantum chaos and the stability of compact quasiaxially symmetric stellarators

    E-Print Network [OSTI]

    Dewar, Robert L.

    - 1 - Anderson localization of ballooning modes, quantum chaos and the stability of compact, isosurfaces are topologically spherical, indicative of strong "quantum chaos". The complexity of QAS marginal

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

    E-Print Network [OSTI]

    California at San Diego, University of

    savings in the radial build has been achieved, reducing the major radius by more than 20%, which. The primary goal of the study is to develop a more compact machine that retains the cost savings associated

  17. SPATIAL DISTRIBUTION AND EVOLUTION OF THE STELLAR POPULATIONS AND CANDIDATE STAR CLUSTERS IN THE BLUE COMPACT DWARF I ZWICKY 18

    SciTech Connect (OSTI)

    Contreras Ramos, R.; Annibali, F.; Fiorentino, G.; Tosi, M.; Clementini, G. [INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna (Italy); Aloisi, A.; Van der Marel, R. P. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Marconi, M.; Musella, I. [INAF-Osservatorio Astronomico di Capodimonte, via Moiariello 16, 80131 Napoli (Italy); Saha, A., E-mail: rodrigo.contreras@oabo.inaf.it [National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726 (United States)

    2011-10-01

    The evolutionary properties and spatial distribution of I Zwicky 18 (IZw18) stellar populations are analyzed by means of Hubble Space Telescope/Advanced Camera for Surveys deep and accurate photometry. A comparison of the resulting color-magnitude diagrams (CMDs) with stellar evolution models indicates that stars of all ages are present in all the system's components, including objects possibly up to 13 Gyr old, intermediate-age stars, and very young ones. The CMDs show evidence of thermally pulsing asymptotic giant branch and carbon stars. classical and ultra-long-period Cepheids as well as long-period variables have been measured. About 20 objects could be unresolved star clusters; these are mostly concentrated in the northwest (NW) portion of the main body (MB). If interpreted with simple stellar population models, these objects indicate a particularly active star formation over the past 100 Myr in IZw18. The stellar spatial distribution shows that the younger ones are more centrally concentrated, while old and intermediate-age stars are distributed homogeneously over the two bodies, although they are more easily detectable at the system's periphery. The oldest stars are most visible in the secondary body (SB) and in the southeast (SE) portion of the MB, where crowding is less severe, but are also present in the rest of the MB, where they are measured with larger uncertainties. The youngest stars are a few Myr old, are located predominantly in the MB, and are mostly concentrated in its NW portion. The SE portion of the MB appears to be in a similar, but not as young, evolutionary stage as the NW, while the SB stars are older than at least 10 Myr. There is then a sequence of decreasing age of the younger stars from the SB to the SE portion of the MB to the NW portion. All our results suggest that IZw18 is not atypical compared to other blue compact dwarfs.

  18. Hydra II: a faint and compact Milky Way dwarf galaxy found in the Survey of the Magellanic Stellar History

    E-Print Network [OSTI]

    Martin, Nicolas F; Besla, Gurtina; Olsen, Knut; Walker, Alistair R; Vivas, A Katherina; Gruendl, Robert A; Muñoz, Ricardo R; Blum, Robert D; Saha, Abhijit; Conn, Blair C; Bell, Eric F; Chu, You-Hua; Cioni, Maria-Rosa L; de Boer, Thomas J L; Gallart, Carme; Jin, Shoko; Kunder, Andrea; Majewski, Steven R; Martinez-Delgado, David; Monachesi, Antonela; Monelli, Matteo; Monteagudo, Lara; Noël, Noelia E D; Olszewski, Edward W; Stringfellow, Guy S; van der Marel, Roeland P; Zaritsky, Denis

    2015-01-01

    We present the discovery of a new dwarf galaxy, Hydra II, found serendipitously within the data from the ongoing Survey of the MAgellanic Stellar History (SMASH) conducted with the Dark Energy Camera on the Blanco 4m Telescope. The new satellite is compact (r_h = 68 +/- 11 pc) and faint (M_V = -4.8 +/- 0.3), but well within the realm of dwarf galaxies. The stellar distribution of HydraII in the color-magnitude diagram is well-described by a metal-poor ([Fe/H] = -2.2) and old (13 Gyr) isochrone and shows a distinct blue horizontal branch, some possible red clump stars, and faint stars that are suggestive of blue stragglers. At a heliocentric distance of 134 +/- 10 kpc, Hydra II is located in a region of the Galactic halo that models have suggested may host material from the leading arm of the Magellanic Stream. A comparison with N-body simulations hints that the new dwarf galaxy could be or could have been a satellite of the Magellanic Clouds.

  19. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would like submit the following comments responseScienceCommunity RelationsCompact soft x-ray

  20. A Near-Infrared Stellar Census of the Blue Compact Dwarf Galaxy VII~Zw~403

    E-Print Network [OSTI]

    Regina E. Schulte-Ladbeck; Ulrich Hopp; Laura Greggio; Mary M. Crone

    1999-09-13

    We present near-infrared single-star photometry for the low-metallicity Blue Compact Dwarf galaxy VII~Zw~403. We achieve limiting magnitudes of F110W~$\\approx$~25.5 and F160W~$\\approx$~24.5 using one of the NICMOS cameras with the HST equivalents of the ground-based J and H filters. The data have a high photometric precision (0.1 mag) and are $>95$% complete down to magnitudes of about 23, far deeper than previous ground-based studies in the near-IR. The color-magnitude diagram contains about 1000 point sources. We provide a preliminary transformation of the near-IR photometry into the ground system...

  1. Compact Stellarator Development Plan

    E-Print Network [OSTI]

    Benefits Stem From 3D Geometry Wendelstein 7-X (Germany) A= 11 · Passive stability at low aspect aspect-symmetry. #12;6 Germany's Wendelstein 7-X (superconducting PE) is under construction, building components

  2. 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]

    for and determining the attractiveness of the compact stellarator as the basis for a fusion power reactor. However and current-drive techniques. This may result in smaller, more powerful fusion reactors. In a statement5/28/08 6:03 PMPrinceton University - PPPL to phase out compact stellarator experiment, upgrade

  3. Simulating gyrokinetic microinstabilities in stellarator geometry with GS2

    SciTech Connect (OSTI)

    Baumgaertel, J. A.; Guttenfelder, W.; Hammett, G. W.; Mikkelsen, D. R.; Rewoldt, G.; Tang, W. M. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Belli, E. A. [General Atomics, San Diego, California 92186 (United States); Dorland, W. [Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Xanthopoulos, P. [Max-Planck-Institut fuer Plasmaphysik, D-17491 Greifswald (Germany)

    2011-12-15

    The nonlinear gyrokinetic code GS2 has been extended to treat non-axisymmetric stellarator geometry. Electromagnetic perturbations and multiple trapped particle regions are allowed. Here, linear, collisionless, electrostatic simulations of the quasi-axisymmetric, three-field period national compact stellarator experiment (NCSX) design QAS3-C82 have been successfully benchmarked against the eigenvalue code FULL. Quantitatively, the linear stability calculations of GS2 and FULL agree to within {approx}10%.

  4. Inference on gravitational waves from coalescences of stellar-mass compact objects and intermediate-mass black holes

    E-Print Network [OSTI]

    Haster, Carl-Johan; Berry, Christopher P L; Stevenson, Simon; Veitch, John; Mandel, Ilya

    2015-01-01

    Gravitational waves from coalescences of neutron stars or stellar-mass black holes into intermediate-mass black holes (IMBHs) of $\\gtrsim 100$ solar masses represent one of the exciting possible sources for advanced gravitational-wave detectors. These sources can provide definitive evidence for the existence of IMBHs, probe globular-cluster dynamics, and potentially serve as tests of general relativity. We analyse the accuracy with which we can measure the masses and spins of the IMBH and its companion in intermediate-mass ratio coalescences. We find that we can identify an IMBH with a mass above $100 ~ M_\\odot$ with $95\\%$ confidence provided the massive body exceeds $130 ~ M_\\odot$. For source masses above $\\sim200 ~ M_\\odot$, the best measured parameter is the frequency of the quasi-normal ringdown. Consequently, the total mass is measured better than the chirp mass for massive binaries, but the total mass is still partly degenerate with spin, which cannot be accurately measured. Low-frequency detector sen...

  5. Compact free-electron laser at the Los Alamos National Laboratory

    SciTech Connect (OSTI)

    Chan, K.C.D.; Meier, K.L.; Nguyen, D.; Sheffield, R.L.; Wang, Tai-Sen F.; Warren, R.W.; Wilson, W.L.; Young, L.M.

    1991-01-01

    The design and construction of second-generation free-electron laser (FEL) system at Los Alamos will be described. comprising state-of-the art components, this FEL system will be sufficiently compact, robust and user-friendly for application in industry, medicine, and research. 11 refs., 11 figs., 2 tabs.

  6. 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

  7. Stellarator Coil Design and Plasma Sensitivity

    SciTech Connect (OSTI)

    Long-Poe Ku and Allen H. Boozer

    2010-11-03

    The rich information contained in the plasma response to external magnetic perturbations can be used to help design stellarator coils more effectively. We demonstrate the feasibility by first devel- oping a simple, direct method to study perturbations in stellarators that do not break stellarator symmetry and periodicity. The method applies a small perturbation to the plasma boundary and evaluates the resulting perturbed free-boundary equilibrium to build up a sensitivity matrix for the important physics attributes of the underlying configuration. Using this sensitivity information, design methods for better stellarator coils are then developed. The procedure and a proof-of-principle application are given that (1) determine the spatial distributions of external normal magnetic field at the location of the unperturbed plasma boundary to which the plasma properties are most sen- sitive, (2) determine the distributions of external normal magnetic field that can be produced most efficiently by distant coils, (3) choose the ratios of the magnitudes of the the efficiently produced magnetic distributions so the sensitive plasma properties can be controlled. Using these methods, sets of modular coils are found for the National Compact Stellarator Experiment (NCSX) that are either smoother or can be located much farther from the plasma boundary than those of the present design.

  8. 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)

    2013-12-15

    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.

  9. Plans for Stellarator Research J.F. Lyon, ORNL

    E-Print Network [OSTI]

    -generation compact stellarator (NGCS) in combination with other fusion program elements to establish physics Dec. 5, 2007 #12;US Stellarator Program in the Post-ITER Era · Exploit compact stellarator advantages as steady-state reactors ­ quiescent, steady-state, high-!, disruption-free operation ­ no power input

  10. Initial Activation Assessment for ARIES Compact Stellarator

    E-Print Network [OSTI]

    Sections Blanket Magnet Plasma Shield/VV Xn through nominal blanket/shield/VV Xn through WC-Shield @ Dmin;Average Neutron Wall Loading 2 MW/m2 Replaceable Component Lifetime 6 FPY for SiC 5 FPY for FS Permanent to FS. · WC filler generates highest activity. 10 -3 10 -1 10 1 10 3 10 5 10 0 10 2 10 4 10 6 10 8 10 10

  11. Reduction of Islands in Full-pressure Stellarator Equilibria

    SciTech Connect (OSTI)

    S.R. Hudson; D.A. Monticello; A.H. Reiman

    2001-04-30

    The control of magnetic islands is a crucial issue in designing Stellarators. Islands are associated with resonant radial magnetic fields at rational rotational-transform surfaces and can lead to chaos and poor plasma confinement. In this article, we show that variations in the resonant fields of a full-pressure stellarator equilibrium can be related to variations in the boundary via a coupling matrix, and inversion of this matrix determines a boundary modification for which the island content is significantly reduced. The numerical procedure is described and the results of island optimization are presented. Equilibria with islands are computed using the Princeton Iterative Equilibrium Solver, and resonant radial fields are calculated via construction of quadratic-flux-minimizing surfaces. A design candidate for the National Compact Stellarator Experiment [Phys. Plasmas 8, 2001], which has a large island, is used to illustrate the technique. Small variations in the boundary shape are used to reduce island size and to reverse the phase of a major island chain.

  12. SEQUENTIAL COMPACTNESS VS. COUNTABLE COMPACTNESS

    E-Print Network [OSTI]

    Nyikos, Peter J.

    are assumed unless explicitly stated. 1. Introduction This article continues the theme, begun in [Ny for general spaces. A standard exercise is that it is equiv- alent to "every sequence has a cluster point. For most of this paper, the general theme will be how "small" a countably com- pact or compact space can

  13. Stellar jets

    E-Print Network [OSTI]

    Thomas J. Maccarone

    2008-05-23

    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.

  14. Compact accelerator

    DOE Patents [OSTI]

    Caporaso, George J. (Livermore, CA); Sampayan, Stephen E. (Manteca, CA); Kirbie, Hugh C. (Los Alamos, NM)

    2007-02-06

    A compact linear accelerator having at least one strip-shaped Blumlein module which guides a propagating wavefront between first and second ends and controls the output pulse at the second end. Each Blumlein module has first, second, and third planar conductor strips, with a first dielectric strip between the first and second conductor strips, and a second dielectric strip between the second and third conductor strips. Additionally, the compact linear accelerator includes a high voltage power supply connected to charge the second conductor strip to a high potential, and a switch for switching the high potential in the second conductor strip to at least one of the first and third conductor strips so as to initiate a propagating reverse polarity wavefront(s) in the corresponding dielectric strip(s).

  15. Compact Reactor

    SciTech Connect (OSTI)

    Williams, Pharis E. [Williams Research, P.O. Box 554, Los Alamos, NM87544 (United States)

    2007-01-30

    Weyl's Gauge Principle of 1929 has been used to establish Weyl's Quantum Principle (WQP) that requires that the Weyl scale factor should be unity. It has been shown that the WQP requires the following: quantum mechanics must be used to determine system states; the electrostatic potential must be non-singular and quantified; interactions between particles with different electric charges (i.e. electron and proton) do not obey Newton's Third Law at sub-nuclear separations, and nuclear particles may be much different than expected using the standard model. The above WQP requirements lead to a potential fusion reactor wherein deuterium nuclei are preferentially fused into helium nuclei. Because the deuterium nuclei are preferentially fused into helium nuclei at temperatures and energies lower than specified by the standard model there is no harmful radiation as a byproduct of this fusion process. Therefore, a reactor using this reaction does not need any shielding to contain such radiation. The energy released from each reaction and the absence of shielding makes the deuterium-plus-deuterium-to-helium (DDH) reactor very compact when compared to other reactors, both fission and fusion types. Moreover, the potential energy output per reactor weight and the absence of harmful radiation makes the DDH reactor an ideal candidate for space power. The logic is summarized by which the WQP requires the above conditions that make the prediction of DDH possible. The details of the DDH reaction will be presented along with the specifics of why the DDH reactor may be made to cause two deuterium nuclei to preferentially fuse to a helium nucleus. The presentation will also indicate the calculations needed to predict the reactor temperature as a function of fuel loading, reactor size, and desired output and will include the progress achieved to date.

  16. Ordinal Compactness Paolo Lipparini

    E-Print Network [OSTI]

    Lipparini, Paolo

    of [, ]-compact- ness. #12;Throughout, let be infinite ordinals. Definition 1 We say that a topological space- ness are the following: · [µ, ]-compactness is equivalent to [, ]-com- pactness, for every with µ · [cf, cf]-compactness implies [, ]-compact- ness. On the other hand, there are many more non- trivial

  17. Compact quiescent galaxies at intermediate redshifts {sup ,}

    SciTech Connect (OSTI)

    Hsu, Li-Yen; Stockton, Alan; Shih, Hsin-Yi

    2014-12-01

    From several searches of the area common to the Sloan Digital Sky Survey and the United Kingdom Infrared Telescope Infrared Deep Sky Survey, we have selected 22 luminous galaxies between z ? 0.4 and z ? 0.9 that have colors and sizes similar to those of the compact quiescent galaxies at z > 2. By exploring structural parameters and stellar populations, we found that most of these galaxies actually formed most of their stars at z < 2 and are generally less compact than those found at z > 2. Several of these young objects are disk-like or possibly prolate. This lines up with several previous studies that found that massive quiescent galaxies at high redshifts often have disk-like morphologies. If these galaxies were to be confirmed to be disk-like, their formation mechanism must be able to account for both compactness and disks. On the other hand, if these galaxies were to be confirmed to be prolate, the fact that prolate galaxies do not exist in the local universe would indicate that galaxy formation mechanisms have evolved over cosmic time. We also found five galaxies forming over 80% of their stellar masses at z > 2. Three of these galaxies appear to have been modified to have spheroid-like morphologies, in agreement with the scenario of 'inside-out' buildup of massive galaxies. The remaining galaxies, SDSS J014355.21+133451.4 and SDSS J115836.93+021535.1, have truly old stellar populations and disk-like morphologies. These two objects would be good candidates for nearly unmodified compact quiescent galaxies from high redshifts that are worth future study.

  18. SAFETY ASSESSMENT OF THE ARIES COMPACT STELLARATOR DESIGN

    E-Print Network [OSTI]

    Raffray, A. René

    -CS by report- ing radiological inventories, decay heat, and radioactive waste management options inventories, decay heat, and radioactive waste ~radwaste! management options ~disposal, recycling with bypass event that mobilizes in-vessel radioactive inventories (e.g., tritium and ero- sion dust from

  19. Stellar feedback efficiencies: supernovae versus stellar winds

    E-Print Network [OSTI]

    Fierlinger, Katharina M; Ntormousi, Evangelia; Fierlinger, Peter; Schartmann, Marc; Ballone, Alessandro; Krause, Martin G H; Diehl, Roland

    2015-01-01

    Stellar winds and supernova (SN) explosions of massive stars ("stellar feedback") create bubbles in the interstellar medium (ISM) and insert newly produced heavy elements and kinetic energy into their surroundings, possibly driving turbulence. Most of this energy is thermalized and immediately removed from the ISM by radiative cooling. The rest is available for driving ISM dynamics. In this work we estimate the amount of feedback energy retained as kinetic energy when the bubble walls have decelerated to the sound speed of the ambient medium. We show that the feedback of the most massive star outweighs the feedback from less massive stars. For a giant molecular cloud (GMC) mass of 1e5 solar masses (as e.g. found in the Orion GMCs) and a star formation efficiency of 8% the initial mass function predicts a most massive star of approximately 60 solar masses. For this stellar evolution model we test the dependence of the retained kinetic energy of the cold GMC gas on the inclusion of stellar winds. In our model w...

  20. Stellar radio astrophysics

    E-Print Network [OSTI]

    Josep M. Paredes

    2004-02-27

    Radio emission has been detected from all the stages of stellar evolution across the HR Diagram. Its presence reveals both astrophysical phenomena and stellar activity which, otherwise, would not be detectable by other means. The development of large, sensitive interferometers has allowed us to resolve the radio structure of several stellar systems, providing insights into the mass transfer process in close binary systems. I review the main characteristics of the radio emission from several kinds of stars, paying special attention to those cases where such an emission originates in relativistic jets.

  1. Nucleosynthesis in stellar flares

    E-Print Network [OSTI]

    V. Tatischeff; J. -P. Thibaud; I. Ribas

    2008-01-11

    Nuclear interactions of ions accelerated at the surface of flaring stars can produce fresh isotopes in stellar atmospheres. Although this nucleosynthesis is not significant for the chemical evolution of the Galaxy, it can be important for a number of measurements of "anomalously" high 6-Li and 7-Li abundances. We discuss the possible role of stellar flares to explain the recent report of high 6-Li abundances in metal-poor halo stars and the well-established correlation between Li abundance and stellar activity in young open clusters. We then study the possibility of observing directly Li production during flares of nearby and active dwarfs of spectral type M.

  2. Stellar granulation and interferometry

    E-Print Network [OSTI]

    Chiavassa, A

    2015-01-01

    Stars are not smooth. Their photosphere is covered by a granulation pattern associated with the heat transport by convection. The convection-related surface structures have different size, depth, and temporal variations with respect to the stellar type. The related activity (in addition to other phenomena such as magnetic spots, rotation, dust, etc.) potentially causes bias in stellar parameters determination, radial velocity, chemical abundances determinations, and exoplanet transit detections. The role of long-baseline interferometric observations in this astrophysical context is crucial to characterize the stellar surface dynamics and correct the potential biases. In this Chapter, we present how the granulation pattern is expected for different kind of stellar types ranging from main sequence to extremely evolved stars of different masses and how interferometric techniques help to study their photospheric dynamics.

  3. 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)

    2014-11-15

    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}.

  4. Estimation of the Mass Outflow Rate From Compact Objects

    E-Print Network [OSTI]

    Sandip K. Chakrabarti

    1998-12-02

    Outflows are common in many astrophysical systems which contain black holes and neutron stars. Difference between stellar outflows and outflows from these systems is that the outflows in these systems have to form out of the inflowing material only. The inflowing material can form a hot and dense cloud surrounding the compact object either because of centrifugal barrier or a denser barrier due to pair plasma or pre-heating effects. This barrier behaves like a stellar surface as far as the mass loss is concerned. We estimate the outflow rate from such considerations. These estimated rates roughly match with the rates in real observations as well as those obtained from numerical experiments.

  5. Compaction Scale Up and Optimization of Cylindrical Fuel Compacts for the Next Generation Nuclear Plant

    SciTech Connect (OSTI)

    Jeffrey J. Einerson; Jeffrey A. Phillips; Eric L. Shaber; Scott E. Niedzialek; W. Clay Richardson; Scott G. Nagley

    2012-10-01

    Multiple process approaches have been used historically to manufacture cylindrical nuclear fuel compacts. Scale-up of fuel compacting was required for the Next Generation Nuclear Plant (NGNP) project to achieve an economically viable automated production process capable of providing a minimum of 10 compacts/minute with high production yields. In addition, the scale-up effort was required to achieve matrix density equivalent to baseline historical production processes, and allow compacting at fuel packing fractions up to 46% by volume. The scale-up approach of jet milling, fluid-bed overcoating, and hot-press compacting adopted in the U.S. Advanced Gas Reactor (AGR) Fuel Development Program involves significant paradigm shifts to capitalize on distinct advantages in simplicity, yield, and elimination of mixed waste. A series of designed experiments have been completed to optimize compaction conditions of time, temperature, and forming pressure using natural uranium oxycarbide (NUCO) fuel. Results from these experiments are included. The scale-up effort is nearing completion with the process installed and operational using nuclear fuel materials. The process is being certified for manufacture of qualification test fuel compacts for the AGR-5/6/7 experiment at the Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL).

  6. EQUILIBRIUM AND STABILITY FOR THE ARIES COMPACT STELLERATOR REACTOR

    SciTech Connect (OSTI)

    TURNBULL AD; LAO LL; COOPER WA; FU GY; GARABEDIAN P; KU LP; ZARNSTORFF MC

    2004-06-01

    Equilibrium and ideal magnetohydrodynamic (MHD) stability studies are reported for Compact Stellarator (ARIES-CS) reactor design equilibria based on a scaled three-period NCSX configuration and a two-period quasi-axisymmetric variant, the MHH2 stellarator. With a stabilizing shell at about twice the minor radius, robustly stable equilibria up to {beta}=6% are achievable. Recent experiments raise questions as to the applicability of linear MHD stability in stellarators since the predicted stability limits appear to be significantly exceeded. A context for interpreting this question, consistent with tokamak experience, is discussed; both the equilibria and nonlinear consequences need to be more carefully considered. Nonlinear stability is analyzed by computing solutions with highly resolved discontinuities to effectively simulate current sheets and islands. This yields {beta} limits in better agreement with measured values.

  7. A National Compact Toroid Research Facility

    E-Print Network [OSTI]

    Washington at Seattle, University of

    Confinement Geometry Linear external vacuum chamber with closed field line plasma configuration. An FRC (Field. Alan L. Hoffman Redmond Plasma Physics Laboratory University of Washington Review for Office of Fusion Energy Sciences (December 12, 2007) #12;Proposed New Facility ­ NCTX (FRC Front End) This presentation

  8. Dark Compact Planets

    E-Print Network [OSTI]

    Laura Tolos; Juergen Schaffner-Bielich

    2015-07-29

    We investigate compact objects formed by dark matter admixed with ordinary matter made of neutron star matter and white dwarf material. We consider non-self annihilating dark matter with an equation-of-state given by an interacting Fermi gas. We find new stable solutions, dark compact planets, with Earth-like masses and radii from few Km to few hundred Km for weakly interacting dark matter. For the strongly interacting dark matter case, we obtain dark compact planets with Jupiter-like masses and radii of few hundred Km. These objects could be formed primordially and accrete white dwarf material subsequently. They could be detected by observing exoplanets with unusually small radii. Moreover, we find that the recently observed 2 ${\\rm M}_{\\odot}$ pulsars set limits on the amount of dark matter inside neutron stars which is, at most, $10^{-6}{\\rm M}_\\odot$.

  9. Dark Compact Planets

    E-Print Network [OSTI]

    Tolos, Laura

    2015-01-01

    We investigate compact objects formed by dark matter admixed with ordinary matter made of neutron star matter and white dwarf material. We consider non-self annihilating dark matter with an equation-of-state given by an interacting Fermi gas. We find new stable solutions, dark compact planets, with Earth-like masses and radii from few Km to few hundred Km for weakly interacting dark matter. For the strongly interacting dark matter case, we obtain dark compact planets with Jupiter-like masses and radii of few hundred Km. These objects could be formed primordially and accrete white dwarf material subsequently. They could be detected by observing exoplanets with unusually small radii. Moreover, we find that the recently observed 2 ${\\rm M}_{\\odot}$ pulsars set limits on the amount of dark matter inside neutron stars which is, at most, $10^{-6}{\\rm M}_\\odot$.

  10. UNIFYING THE ZOO OF JET-DRIVEN STELLAR EXPLOSIONS

    SciTech Connect (OSTI)

    Lazzati, Davide; Blackwell, Christopher H.; Morsony, Brian J.; Begelman, Mitchell C.

    2012-05-01

    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.

  11. Industrial Optimization Compact Course

    E-Print Network [OSTI]

    Kirches, Christian

    Industrial Optimization Compact Course and Challenge Workshop Optimization plays a crucial role in designing and conducting industrial processes. The potential gains range from saving valuable resources over makers from industry and academia to initiate new projects and to foster new structured collaborations

  12. TIDAL NOVAE IN COMPACT BINARY WHITE DWARFS

    SciTech Connect (OSTI)

    Fuller, Jim; Lai Dong [Department of Astronomy, Cornell University, Ithaca, NY 14850 (United States)

    2012-09-01

    Compact binary white dwarfs (WDs) undergoing orbital decay due to gravitational radiation can experience significant tidal heating prior to merger. In these WDs, the dominant tidal effect involves the excitation of outgoing gravity waves in the inner stellar envelope and the dissipation of these waves in the outer envelope. As the binary orbit decays, the WDs are synchronized from outside in (with the envelope synchronized first, followed by the core). We examine the deposition of tidal heat in the envelope of a carbon-oxygen WD and study how such tidal heating affects the structure and evolution of the WD. We show that significant tidal heating can occur in the star's degenerate hydrogen layer. This layer heats up faster than it cools, triggering runaway nuclear fusion. Such 'tidal novae' may occur in all WD binaries containing a CO WD, at orbital periods between 5 minutes and 20 minutes, and precede the final merger by 10{sup 5}-10{sup 6} years.

  13. Submillimeter galaxies as progenitors of compact quiescent galaxies

    SciTech Connect (OSTI)

    Toft, S.; Zirm, A.; Krogager, J.-K.; Man, A. W. S.; Smol?i?, V.; Krpan, J.; Magnelli, B.; Karim, A.; Michalowski, M.; Capak, P.; Sheth, K.; Schawinski, K.; Wuyts, S.; Lutz, D.; Staguhn, J.; Berta, S.; Sanders, D.; Mccracken, H.; Riechers, D.

    2014-02-20

    Three billion years after the big bang (at redshift z = 2), half of the most massive galaxies were already old, quiescent systems with little to no residual star formation and extremely compact with stellar mass densities at least an order of magnitude larger than in low-redshift ellipticals, their descendants. Little is known about how they formed, but their evolved, dense stellar populations suggest formation within intense, compact starbursts 1-2 Gyr earlier (at 3 < z < 6). Simulations show that gas-rich major mergers can give rise to such starbursts, which produce dense remnants. Submillimeter-selected galaxies (SMGs) are prime examples of intense, gas-rich starbursts. With a new, representative spectroscopic sample of compact, quiescent galaxies at z = 2 and a statistically well-understood sample of SMGs, we show that z = 3-6 SMGs are consistent with being the progenitors of z = 2 quiescent galaxies, matching their formation redshifts and their distributions of sizes, stellar masses, and internal velocities. Assuming an evolutionary connection, their space densities also match if the mean duty cycle of SMG starbursts is 42{sub ?29}{sup +40} Myr (consistent with independent estimates), which indicates that the bulk of stars in these massive galaxies were formed in a major, early surge of star formation. These results suggest a coherent picture of the formation history of the most massive galaxies in the universe, from their initial burst of violent star formation through their appearance as high stellar-density galaxy cores and to their ultimate fate as giant ellipticals.

  14. Progress in Compact Toroid Experiments

    SciTech Connect (OSTI)

    Dolan, Thomas James

    2002-09-01

    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.

  15. 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)

    2010-10-01

    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}.

  16. Compact proton spectrometers for measurements of shock

    SciTech Connect (OSTI)

    Mackinnon, A; Zylstra, A; Frenje, J A; Seguin, F H; Rosenberg, M J; Rinderknecht, H G; Johnson, M G; Casey, D T; Sinenian, N; Manuel, M; Waugh, C J; Sio, H W; Li, C K; Petrasso, R D; Friedrich, S; Knittel, K; Bionta, R; McKernan, M; Callahan, D; Collins, G; Dewald, E; Doeppner, T; Edwards, M J; Glenzer, S H; Hicks, D; Landen, O L; London, R; Meezan, N B

    2012-05-02

    The compact Wedge Range Filter (WRF) proton spectrometer was developed for OMEGA and transferred to the National Ignition Facility (NIF) as a National Ignition Campaign (NIC) diagnostic. The WRF measures the spectrum of protons from D-{sup 3}He reactions in tuning-campaign implosions containing D and {sup 3}He gas; in this work we report on the first proton spectroscopy measurement on the NIF using WRFs. The energy downshift of the 14.7-MeV proton is directly related to the total {rho}R through the plasma stopping power. Additionally, the shock proton yield is measured, which is a metric of the final merged shock strength.

  17. Compact Spreader Schemes

    SciTech Connect (OSTI)

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

    2014-07-25

    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.

  18. The Dartmouth Stellar Evolution Database

    E-Print Network [OSTI]

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

    2008-04-28

    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.

  19. Bending Waves in Flattened Stellar Systems a Department of Mathematics

    E-Print Network [OSTI]

    Bending Waves in Flattened Stellar Systems a C. Hunter Department of Mathematics Florida State the explanation of galactic warps, that is the topic of this paper. Massive dark halos may very well play a major supported in part by National Science Foundation Grant DMS­9304012. This paper is based on an invited talk

  20. Sandia National Laboratories: News: Publications: Lab News

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

    13, 2014 AREVA building on Sandia's molten salt expertise These mirrors at the National Solar Thermal Test Facility, called Compact Linear Fresnel Reflectors, are being used in...

  1. Crystalline chiral condensates as a component of compact stars

    E-Print Network [OSTI]

    S. Carignano; E. J. Ferrer; V. de la Incera; L. Paulucci

    2015-11-04

    We investigate the influence of spatially inhomogeneous chiral symmetry-breaking condensates in a magnetic field background on the equation of state for compact stellar objects. After building a hybrid star composed of nuclear and quark matter using the Maxwell construction, we find, by solving the Tolman-Oppenheimer-Volkoff equations for stellar equilibrium, that our equation of state supports stars with masses around 2 $M_\\odot$ for values of the magnetic field that are in accordance with those inferred from magnetar data. The inclusion of a weak vector interaction term in the quark part allows one to reach 2 solar masses for relatively small central magnetic fields, making this composition a viable possibility for describing the internal degrees of freedom of this class of astrophysical objects.

  2. Crystalline chiral condensates as a component of compact stars

    E-Print Network [OSTI]

    Carignano, S; de la Incera, V; Paulucci, L

    2015-01-01

    We investigate the influence of spatially inhomogeneous chiral symmetry-breaking condensates in a magnetic field background on the equation of state for compact stellar objects. After building a hybrid star composed of nuclear and quark matter using the Maxwell construction, we find, by solving the Tolman-Oppenheimer-Volkoff equations for stellar equilibrium, that our equation of state supports stars with masses around 2 $M_\\odot$ for values of the magnetic field that are in accordance with those inferred from magnetar data. The inclusion of a weak vector interaction term in the quark part allows to reach 2 solar masses for relatively small central magnetic fields, making this composition a viable possibility for describing the internal degrees of freedom of this class of astrophysical objects.

  3. Crystalline chiral condensates as a component of compact stars

    E-Print Network [OSTI]

    S. Carignano; E. J. Ferrer; V. de la Incera; L. Paulucci

    2015-05-19

    We investigate the influence of spatially inhomogeneous chiral symmetry-breaking condensates in a magnetic field background on the equation of state for compact stellar objects. After building a hybrid star composed of nuclear and quark matter using the Maxwell construction, we find, by solving the Tolman-Oppenheimer-Volkoff equations for stellar equilibrium, that our equation of state supports stars with masses around 2 $M_\\odot$ for values of the magnetic field that are in accordance with those inferred from magnetar data. The inclusion of a weak vector interaction term in the quark part allows to reach 2 solar masses for relatively small central magnetic fields, making this composition a viable possibility for describing the internal degrees of freedom of this class of astrophysical objects.

  4. Accretion in Compact Binaries

    E-Print Network [OSTI]

    Andrew R. King

    2003-03-26

    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. Compact electrostatic comb actuator

    DOE Patents [OSTI]

    Rodgers, M. Steven (Albuquerque, NM); Burg, Michael S. (Albuquerque, NM); Jensen, Brian D. (Albuquerque, NM); Miller, Samuel L. (Albuquerque, NM); Barnes, Stephen M. (Albuquerque, NM)

    2000-01-01

    A compact electrostatic comb actuator is disclosed for microelectromechanical (MEM) applications. The actuator is based upon a plurality of meshed electrostatic combs, some of which are stationary and others of which are moveable. One or more restoring springs are fabricated within an outline of the electrostatic combs (i.e. superposed with the moveable electrostatic combs) to considerably reduce the space required for the actuator. Additionally, a truss structure is provided to support the moveable electrostatic combs and prevent bending or distortion of these combs due to unbalanced electrostatic forces or external loading. The truss structure formed about the moveable electrostatic combs allows the spacing between the interdigitated fingers of the combs to be reduced to about one micron or less, thereby substantially increasing the number of active fingers which can be provided in a given area. Finally, electrostatic shields can be used in the actuator to substantially reduce unwanted electrostatic fields to further improve performance of the device. As a result, the compact electrostatic comb actuator of the present invention occupies only a fraction of the space required for conventional electrostatic comb actuators, while providing a substantial increase in the available drive force (up to one-hundred times).

  6. 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...

  7. Mass radius relation of compact stars in the braneworld

    SciTech Connect (OSTI)

    Castro, Luis B.; Menezes, Débora P.; Alloy, Marcelo D. E-mail: alloy@uffs.edu.br

    2014-08-01

    The braneworld scenario, based on the fact that the four dimension space-time is a hyper-surface of a five dimensional manifold, was shown to deal in a satisfactory way with the hierarchy problem. In this work we study macroscopic stellar properties of compact stars from the braneworld point of view. Using neutron star equations of state, we test the possibility of extra dimensions by solving the brane Tolman-Oppenheimer-Volkoff equations obtained for three kinds of possible compact objects: hadronic, hybrid and quark stars. By comparing the macroscopic solutions with observational constraints, we establish a brane tension lower limit and the value for which the Tolman-Oppenheimer-Volkoff equations in the braneworld converge to the usual Tolman-Oppenheimer-Volkoff equations.

  8. Evidence for a binary origin of a central compact object

    E-Print Network [OSTI]

    Doroshenko, Victor; Kavanagh, Patrick; Santangelo, Andrea; Suleimanov, Valery; Klochkov, Dmitry

    2015-01-01

    Central compact objects are thought to be young thermally emitting isolated neutron stars that were born during the preceding core-collapse supernova explosion. Here we present the first evidence that at least in one case the neutron star must have formed within a binary system. The former stellar companion, surrounded by a dust shell with an estimated mass of $\\sim0.4-1.5M_\\odot$ , is going through the final stages of its own evolution as a post-asymptotic giant branch star. We argue that accretion of matter supplied by the companion soon after the supernova explosion is likely responsible for dampening of the magnetic field of the central compact object to its presently low value.

  9. Compact acoustic refrigerator

    SciTech Connect (OSTI)

    Bennett, G.A.

    1991-12-31

    This invention is comprised of a compact acoustic refrigeration system that 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.

  10. Compact vacuum insulation

    DOE Patents [OSTI]

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

    1993-01-05

    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.

  11. Compact vacuum insulation embodiments

    DOE Patents [OSTI]

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

    1992-04-28

    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.

  12. Compact cogeneration system

    SciTech Connect (OSTI)

    Cabral, R.E.

    1991-07-23

    This patent describes a compact heat exchanger for heating water with, and cleaning, the exhaust gas of an internal combustion engine of a cogeneration system. It comprises an outer shell having gas inlet means for entry of exhaust gas from the engine, gas outlet means for outflow of exhaust gas, water inlet means for entry of water to be heated, and water outlet means for outflow of water; a housing positioned within and spaced from the outer shell to form a flow channel therebetween; a coil in communication with the water inlet means and the water outlet means and positioned in the flow channel between the housing and the outer shell; catalytic converter material within the housing; wherein the housing is connected to the gas inlet means to receive exhaust gas from the engine and to direct the exhaust gas through the catalytic converter material.

  13. Compact acoustic refrigerator

    DOE Patents [OSTI]

    Bennett, Gloria A. (Los Alamos, NM)

    1992-01-01

    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.

  14. Compact acoustic refrigerator

    DOE Patents [OSTI]

    Bennett, G.A.

    1992-11-24

    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.

  15. A Compact Ring Design with Tunable Momentum Compaction

    SciTech Connect (OSTI)

    Sun, Y.; ,

    2012-05-17

    A storage ring with tunable momentum compaction has the advantage in achieving different RMS bunch length with similar RF capacity, which is potentially useful for many applications, such as linear collider damping ring and predamping ring where injected beam has a large energy spread and a large transverse emittance. A tunable bunch length also makes the commissioning and fine tuning easier in manipulating the single bunch instabilities. In this paper, a compact ring design based on a supercell is presented, which achieves a tunable momentum compaction while maintaining a large dynamic aperture.

  16. Use of a BCD for compaction control 

    E-Print Network [OSTI]

    Li, Yanfeng

    2005-11-01

    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...

  17. Compact vacuum insulation

    DOE Patents [OSTI]

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

    1992-01-01

    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.

  18. Compact neutron generator

    DOE Patents [OSTI]

    Leung, Ka-Ngo; Lou, Tak Pui

    2005-03-22

    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.

  19. Compact vacuum insulation

    DOE Patents [OSTI]

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

    1992-10-27

    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. Compaction managed mirror bend achromat

    DOE Patents [OSTI]

    Douglas, David (Yorktown, VA)

    2005-10-18

    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.

  1. New considerations for compact cyclotrons

    E-Print Network [OSTI]

    Marshall, Eric S. (Eric Scott)

    2012-01-01

    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 ...

  2. Laboratory compaction of cohesionless sands 

    E-Print Network [OSTI]

    Delphia, John Girard

    1998-01-01

    A total of 62 cohesiveness sands were tested to rographics. investigate the importance of the water content, grain size distribution, grading of the soil, particle shape, grain crushing during testing and laboratory compaction test method...

  3. 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)

    2009-12-28

    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.

  4. Stellar magnetic activity and their influence on the habitability of exoplanets

    E-Print Network [OSTI]

    Lüftinger, T; Johnstone, C P

    2015-01-01

    Stellar magnetism, explorable via polarimetry, is a crucial driver of activity, ionization, photodissociation, chemistry and winds in stellar environments. Thus it has an important impact on the atmospheres and magnetospheres of surrounding planets. Modeling of stellar magnetic fields and their winds is extremely challenging, both from the observational and the theoretical points of view, and only recent ground breaking advances in observational instrumentation - as were discussed during this Symposium - and a deeper theoretical understanding of magnetohydrodynamic processes in stars enable us to model stellar magnetic fields and winds and the resulting influence on surrounding planets in more and more detail. We have initiated a national and international research network (NFN): 'Pathways to Habitability - From Disks to Active Stars, Planets to Life', to address questions on the formation and habitability of environments in young, active stellar/planetary systems. In this contribution we discuss the work we ...

  5. Suppression of vertical instability in elongated current-carrying plasmas by applying stellarator rotational transform

    SciTech Connect (OSTI)

    ArchMiller, M. C.; Cianciosa, M. R.; Ennis, D. A.; Hanson, J. D.; Hartwell, G. J.; Hebert, J. D.; Herfindal, J. L.; Knowlton, S. F.; Ma, X.; Maurer, D. A.; Pandya, M. D.; Traverso, P. [Physics Department, Auburn University, Auburn, Alabama 36849 (United States)

    2014-05-15

    The passive stability of vertically elongated current-carrying toroidal plasmas has been investigated in the Compact Toroidal Hybrid, a stellarator/tokamak hybrid device. In this experiment, the fractional transform f, defined as the ratio of the imposed external rotational transform from stellarator coils to the total rotational transform, was varied from 0.04 to 0.50, and the elongation ? was varied from 1.4 to 2.2. Plasmas that were vertically unstable were evidenced by motion of the plasma in the vertical direction. Vertical drifts are measured with a set of poloidal field pickup coils. A three chord horizontally viewing interferometer and a soft X-ray diode array confirmed the drifts. Plasmas with low fractional transform and high elongation are the most susceptible to vertical instability, consistent with analytic predictions that the vertical mode in elongated plasmas can be stabilized by the poloidal field of a relatively weak stellarator equilibrium.

  6. Global Properties of Neutral Hydrogen in Compact Groups

    E-Print Network [OSTI]

    Walker, Lisa May; Gallagher, Sarah C; Privon, George C; Kepley, Amanda A; Whelan, David G; Desjardins, Tyler D; Zabludoff, Ann I

    2015-01-01

    Compact groups of galaxies provide a unique environment to study the evolution of galaxies amid frequent gravitational encounters. These nearby groups have conditions similar to those in the earlier universe when galaxies were assembled and give us the opportunity to witness hierarchical formation in progress. To understand how the compact group environment affects galaxy evolution, we examine the gas and dust in these groups. We present new single-dish GBT neutral hydrogen (HI) observations of 30 compact groups and define a new way to quantify the group HI content as the HI-to-stellar mass ratio of the group as a whole. We compare the HI content with mid-IR indicators of star formation and optical [g-r] color to search for correlations between group gas content and star formation activity of individual group members. Quiescent galaxies tend to live in HI-poor groups, and galaxies with active star formation are more commonly found in HI-rich groups. Intriguingly, we also find "rogue" galaxies whose star forma...

  7. 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)

    2013-08-10

    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.

  8. Proc. 10th Int. Conf. on Stellarators, Madrid, EUR-CIEMAT 30 (1995) 89 The application of wavelet bicoherence to

    E-Print Network [OSTI]

    van Milligen, Boudewijn

    1995-01-01

    1 Proc. 10th Int. Conf. on Stellarators, Madrid, EUR-CIEMAT 30 (1995) 89 The application of wavelet, L. García2 Asociación EURATOM-CIEMAT, Madrid, Spain 1Oak Ridge National Laboratory, Oak Ridge

  9. Compact orthogonal NMR field sensor

    DOE Patents [OSTI]

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

    2009-02-03

    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. Compact accelerator for medical therapy

    DOE Patents [OSTI]

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

    2010-05-04

    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.

  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)

    2007-06-26

    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 intermediates in RNA folding

    SciTech Connect (OSTI)

    Woodson, S.A. (JHU)

    2011-12-14

    Large noncoding RNAs fold into their biologically functional structures via compact yet disordered intermediates, which couple the stable secondary structure of the RNA with the emerging tertiary fold. The specificity of the collapse transition, which coincides with the assembly of helical domains, depends on RNA sequence and counterions. It determines the specificity of the folding pathways and the magnitude of the free energy barriers to the ensuing search for the native conformation. By coupling helix assembly with nascent tertiary interactions, compact folding intermediates in RNA also play a crucial role in ligand binding and RNA-protein recognition.

  13. Modular Stellarator Fusion Reactor concept

    SciTech Connect (OSTI)

    Miller, R.L.; Krakowski, R.A.

    1981-08-01

    A preliminary conceptual study is made of the Modular Stellarator Reactor (MSR). A steady-state ignited, DT-fueled, magnetic fusion reactor is proposed for use as a central electric-power station. The MSR concept combines the physics of the classic stellarator confinement topology with an innovative, modular-coil design. Parametric tradeoff calculations are described, leading to the selection of an interim design point for a 4-GWt plant based on Alcator transport scaling and an average beta value of 0.04 in an l = 2 system with a plasma aspect ratio of 11. The physics basis of the design point is described together with supporting magnetics, coil-force, and stress computations. The approach and results presented herein will be modified in the course of ongoing work to form a firmer basis for a detailed conceptual design of the MSR.

  14. 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

  15. Laser driven compact ion accelerator

    DOE Patents [OSTI]

    Tajima, Toshiki

    2005-03-15

    A laser driven compact ion source including a light source that produces an energy pulse, a light source guide that guides the energy pulse to a target and produces an ion beam. The ion beam is transported to a desired destination.

  16. Mesoscale Simulations of Power Compaction

    SciTech Connect (OSTI)

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

    2009-08-06

    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.

  17. Steady state relativistic stellar dynamics around a massive black hole

    E-Print Network [OSTI]

    Bar-Or, Ben

    2015-01-01

    A massive black hole (MBH) consumes stars whose orbits evolve into the small phase-space volume of unstable orbits, the "loss-cone", which take them directly into the MBH, or close enough to interact strongly with it. The resulting phenomena: tidal heating and tidal disruption, binary capture and hyper-velocity star ejection, gravitational wave (GW) emission by inspiraling compact remnants, or hydrodynamical interactions with an accretion disk, are of interest as they can produce observable signatures and thereby reveal the existence of the MBH, affect its mass and spin evolution, probe strong gravity, and provide information on stars and gas near the MBH. The continuous loss of stars and the processes that resupply them shape the central stellar distribution. We investigate relativistic stellar dynamics near the loss-cone of a non-spinning MBH in steady-state analytically and by Monte Carlo simulations of the diffusion of the orbital parameters. These take into account Newtonian mass precession due to enclos...

  18. Dynamical Tides in Compact White Dwarf Binaries: Influence of Rotation

    E-Print Network [OSTI]

    Fuller, Jim

    2014-01-01

    Tidal interactions play an important role in the evolution and ultimate fate of compact white dwarf (WD) binaries. Not only do tides affect the pre-merger state (such as temperature and rotation rate) of the WDs, but they may also determine which systems merge and which undergo stable mass transfer. In this paper, we attempt to quantify the effects of rotation on tidal angular momentum transport in binary stars, with specific calculations applied to WD stellar models. We incorporate the effect of rotation using the traditional approximation, in which the dynamically excited gravity waves within the WDs are transformed into gravito-inertial Hough waves. The Coriolis force has only a minor effect on prograde gravity waves, and previous results predicting the tidal spin-up and heating of inspiraling WDs are not significantly modified. However, rotation strongly alters retrograde gravity waves and inertial waves, with important consequences for the tidal spin-down of accreting WDs. We identify new dynamical tidal...

  19. Tank farms compacted low-level waste

    SciTech Connect (OSTI)

    Hetzer, D.C.

    1997-08-01

    This report describes the process of Low-Level Waste (LLW) volume reduction by compaction. Also included is the data used for characterization of LLW destined for compaction. Scaling factors (ratios) are formed based on data contained in this report.

  20. Tank farms compacted low level waste

    SciTech Connect (OSTI)

    Waters, M.S., Westinghouse Hanford

    1996-07-01

    This report describes the process of Low Level Waste (LLW) volume reduction by compaction. Also included is the data used for characterization of LLW destined for compaction. Scaling factors (ratios) are formed based on data contained in this report.

  1. 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

  2. Compact magnetic energy storage module

    DOE Patents [OSTI]

    Prueitt, M.L.

    1994-12-20

    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.

  3. Compact portable diffraction moire interferometer

    DOE Patents [OSTI]

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

    1988-05-23

    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.

  4. Compact magnetic energy storage module

    DOE Patents [OSTI]

    Prueitt, Melvin L. (Los Alamos, NM)

    1994-01-01

    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.

  5. 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

  6. 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

  7. 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

  8. Accommodation of prompt alpha-particle loss in a compact stellarator power plant

    E-Print Network [OSTI]

    Najmabadi, Farrokh

    . This results in a non-negligible fraction of alpha- particles being promptly lost from the plasma and hitting the plasma facing components (PFC) at energies close to their born value of 3.5 MeV. The PFC armor must not only accommodate the heat load from the alpha-particle flux but it must also accommodate the He

  9. Accepted Manuscript Accommodation of prompt alpha-particle loss in a compact stellarator power

    E-Print Network [OSTI]

    Raffray, A. René

    . This results in a non-negligible fraction of alpha particles being promptly lost from the plasma and hitting the plasma facing components (PFC) at energies close to their born value of 3.5 MeV. The PFC armor must not only accommodate the heat load from the alpha-particle flux but it must also accommodate the He

  10. Dynamics of Triaxial Stellar Systems

    E-Print Network [OSTI]

    David Merritt

    1996-11-11

    Recent work on the dynamics of triaxial stellar systems is reviewed. The motion of boxlike orbits in realistic triaxial potentials is generically stochastic. The degree to which the stochasticity manifests itself in the dynamics depends on the chaotic mixing timescale, which is a small multiple of the crossing time in triaxial models with steep cusps or massive central singularities. Low-luminosity ellipticals, which have the steepest cusps and the shortest dynamical times, are less likely than bright ellipticals to have strongly triaxial shapes. The observational evidence for triaxiality is reviewed; departures from axisymmetry in early-type galaxies are often found to be associated with evidence of recent interactions or with the presence of a bar.

  11. Modeling Solar Activity Bayesian Analysis of Stellar Evolution

    E-Print Network [OSTI]

    Wolfe, Patrick J.

    Modeling Solar Activity Bayesian Analysis of Stellar Evolution Astrostatistical Analysis in Solar, David Astrostatistical Analysis in Solar and Stellar Physics #12;Modeling Solar Activity Bayesian Analysis of Stellar Evolution Outline 1 Modeling Solar Activity Background Morphological Feature Extraction

  12. Effects of moderate rotation on stellar pulsations, nonperturbative methods Corinne Neuforge

    E-Print Network [OSTI]

    Meyer-Vernet, Nicole

    Alamos National Laboratory, Los Alamos, NM 87545, USA Maryline Briquet and Richard Scuflaire Institut d. The first project is conducted by M. Briquet. She is studying SPB variables. The rotation periods). This theory is well established, and M. Briquet plans to include it in our stellar stability codes. The second

  13. Innovative High Stellarators Don Spong (spongda@ornl.gov, July 27, 2012)

    E-Print Network [OSTI]

    significant limits on how far the cost of fusion produced electricity can be lowered. This issue could becomeInnovative High Stellarators Don Spong (spongda@ornl.gov, July 27, 2012) Oak Ridge National be costly and time-consuming to construct. Prior to restarting any research in this direction, a goal should

  14. The Black Hole in the Compact, High-dispersion Galaxy NGC 1271

    E-Print Network [OSTI]

    Walsh, Jonelle L; Gebhardt, Karl; Y?ld?r?m, Ak?n; Gültekin, Kayhan; Husemann, Bernd; Richstone, Douglas O

    2015-01-01

    Located in the Perseus cluster, NGC 1271 is an early-type galaxy with a small effective radius of 2.2 kpc and a large stellar velocity dispersion of 276 km/s for its K-band luminosity of 8.9x10^{10} L_sun. We present a mass measurement for the black hole in this compact, high-dispersion galaxy using observations from the integral field spectrograph NIFS on the Gemini North telescope assisted by laser guide star adaptive optics, large-scale integral field unit observations with PPAK at the Calar Alto Observatory, and Hubble Space Telescope WFC3 imaging observations. We are able to map out the stellar kinematics on small spatial scales, within the black hole sphere of influence, and on large scales that extend out to four times the galaxy's effective radius. We find that the galaxy is rapidly rotating and exhibits a sharp rise in the velocity dispersion. Through the use of orbit-based stellar dynamical models, we determine that the black hole has a mass of (3.0^{+1.0}_{-1.1}) x 10^9 M_sun and the H-band stellar...

  15. Compact submanifolds supporting singular interactions

    SciTech Connect (OSTI)

    Kaynak, Burak Tevfik Teoman Turgut, O.

    2013-12-15

    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.

  16. Compacted carbon for electrochemical cells

    DOE Patents [OSTI]

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

    1997-10-14

    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.

  17. Method for preparing porous metal hydride compacts

    DOE Patents [OSTI]

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

    1980-01-21

    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.

  18. 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)

    1981-01-01

    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.

  19. KEPLER MISSION STELLAR AND INSTRUMENT NOISE PROPERTIES

    SciTech Connect (OSTI)

    Gilliland, Ronald L.; Chaplin, William J.; Elsworth, Yvonne P.; Miglio, Andrea; Dunham, Edward W.; Argabright, Vic S.; Borucki, William J.; Bryson, Stephen T.; Koch, David G.; Walkowicz, Lucianne M.; Basri, Gibor; Buzasi, Derek L.; Caldwell, Douglas A.; Jenkins, Jon M.; Van Cleve, Jeffrey; Welsh, William F.

    2011-11-01

    Kepler mission results are rapidly contributing to fundamentally new discoveries in both the exoplanet and asteroseismology fields. The data returned from Kepler are unique in terms of the number of stars observed, precision of photometry for time series observations, and the temporal extent of high duty cycle observations. As the first mission to provide extensive time series measurements on thousands of stars over months to years at a level hitherto possible only for the Sun, the results from Kepler will vastly increase our knowledge of stellar variability for quiet solar-type stars. Here, we report on the stellar noise inferred on the timescale of a few hours of most interest for detection of exoplanets via transits. By design the data from moderately bright Kepler stars are expected to have roughly comparable levels of noise intrinsic to the stars and arising from a combination of fundamental limitations such as Poisson statistics and any instrument noise. The noise levels attained by Kepler on-orbit exceed by some 50% the target levels for solar-type, quiet stars. We provide a decomposition of observed noise for an ensemble of 12th magnitude stars arising from fundamental terms (Poisson and readout noise), added noise due to the instrument and that intrinsic to the stars. The largest factor in the modestly higher than anticipated noise follows from intrinsic stellar noise. We show that using stellar parameters from galactic stellar synthesis models, and projections to stellar rotation, activity, and hence noise levels reproduce the primary intrinsic stellar noise features.

  20. Super compact equation for water waves

    E-Print Network [OSTI]

    Dyachenko, A I; Zakharov, V E

    2015-01-01

    We derive very simple compact equation for gravity water waves which includes nonlinear wave term (`a la NLSE) and advection term (may results in wave breaking).

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

    SciTech Connect (OSTI)

    None

    2010-10-01

    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.

  2. Electron screening effect on stellar thermonuclear fusion

    E-Print Network [OSTI]

    Potekhin, A Y

    2013-01-01

    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.

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

    E-Print Network [OSTI]

    Nihei, K.T.

    2012-01-01

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

  4. Wind anisotropy and stellar evolution

    E-Print Network [OSTI]

    Cyril Georgy; Georges Meynet; André Maeder

    2008-07-31

    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.

  5. Cooling of Color Superconducting Compact Stars

    E-Print Network [OSTI]

    David Blaschke

    2006-03-26

    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.

  6. Compact Process Development at Babcock & Wilcox

    SciTech Connect (OSTI)

    Eric Shaber; Jeffrey Phillips

    2012-03-01

    Multiple process approaches have been used historically to manufacture cylindrical nuclear fuel compacts. Scale-up of fuel compacting was required for the Next Generation Nuclear Plant (NGNP) project to achieve an economically viable automated production process capable of providing a minimum of 10 compacts/minute with high production yields. In addition, the scale-up effort was required to achieve matrix density equivalent to baseline historical production processes, and allow compacting at fuel packing fractions up to 46% by volume. The scale-up approach of jet milling, fluid-bed overcoating, and hot-press compacting adopted in the U.S. Advanced Gas Reactor (AGR) Fuel Development Program involves significant paradigm shifts to capitalize on distinct advantages in simplicity, yield, and elimination of mixed waste. A series of compaction trials have been completed to optimize compaction conditions of time, temperature, and forming pressure using natural uranium oxycarbide (NUCO) fuel at packing fractions exceeding 46% by volume. Results from these trials are included. The scale-up effort is nearing completion with the process installed and operable using nuclear fuel materials. Final process testing is in progress to certify the process for manufacture of qualification test fuel compacts in 2012.

  7. MAST-Upgrade Advancing compact fusion sources

    E-Print Network [OSTI]

    MAST-Upgrade Advancing compact fusion sources #12;#12;The Mega Amp Spherical Tokamak (MAST) is the centrepiece of the UK's fusion research programme. It has led studies into the spherical tokamak, a compact to the drive towards commercial fusion power. 1. Testing reactor concepts. MAST-Upgrade will be the first

  8. MAST Upgrade Advancing compact fusion sources

    E-Print Network [OSTI]

    MAST Upgrade Advancing compact fusion sources 4 1 Off) is the centrepiece of the UK's fusion programme. MAST has led studies into the spherical tokamak, a compact fusion research: · Make the case for a fusion Component Test Facility. · Add to the knowledge base for ITER

  9. Compact Fusion Catherine Hope and Graham Hutton

    E-Print Network [OSTI]

    Hutton, Graham

    Compact Fusion Catherine Hope and Graham Hutton School of Computer Science and IT, University;Compact Fusion unfold :: (a Bool) (a b) (a a) a [b] unfold p hd tl = f where f x = if p x and collapses it in some way. The space efficiency of this composition may be improved by applying fusion

  10. 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

  11. Spiegel -A Visualization System for Dense Stellar Systems

    E-Print Network [OSTI]

    Bischof, Hans-Peter

    - body simulations of dense stellar systems. The visualization system al- lows ex- ploring the simulation

  12. Density variations and anomalies in palladium compacts

    SciTech Connect (OSTI)

    Back, D.; Jones, T.; Ransick, M.; Walburg, T.; Werkmeister, D.

    1992-05-14

    Low-density compacts of palladium powder have relative densities of about 30{plus minus}10% TD. The variations in density are of concern for operations such as chemical/hydrogen pump systems because heat, mass, and momentum transport properties can be affected. Variations in density result from the inherent nature and interacting forces of UASA compaction of powder in cylinders. In addition to these expected variations, discontinuous density anomalies, such as cracks or high density ridges, are also found. An anomaly of particular concern was found to resemble a steer's head.'' it is a symmetrical region of low density located at or near the center of a compact. Typically, this region is surrounded by a band of high density, compacted palladium that sometimes exceeds the density of the surrounding compact matrix by a factor of three. This report examines these density variations and anomalies both theoretically and empirically.

  13. Density variations and anomalies in palladium compacts

    SciTech Connect (OSTI)

    Back, D.; Jones, T.; Ransick, M.; Walburg, T.; Werkmeister, D.

    1992-05-14

    Low-density compacts of palladium powder have relative densities of about 30{plus_minus}10% TD. The variations in density are of concern for operations such as chemical/hydrogen pump systems because heat, mass, and momentum transport properties can be affected. Variations in density result from the inherent nature and interacting forces of UASA compaction of powder in cylinders. In addition to these expected variations, discontinuous density anomalies, such as cracks or high density ridges, are also found. An anomaly of particular concern was found to resemble a ``steer`s head.`` it is a symmetrical region of low density located at or near the center of a compact. Typically, this region is surrounded by a band of high density, compacted palladium that sometimes exceeds the density of the surrounding compact matrix by a factor of three. This report examines these density variations and anomalies both theoretically and empirically.

  14. Please cite this article in press as: A. Sagara, et al., Review of stellarator/heliotron design issues towards MFE DEMO, Fusion Eng. Des. (2010), doi:10.1016/j.fusengdes.2010.03.041

    E-Print Network [OSTI]

    Najmabadi, Farrokh

    2010-01-01

    reactor ARIES-CS (compact stellarator). Therefore, from the aspect towards MFE DEMO, this paper makes issues towards MFE DEMO, Fusion Eng. Des. (2010), doi:10.1016/j.fusengdes.2010.03.041 ARTICLE IN PRESS GModel FUSION-5156; No.of Pages6 Fusion Engineering and Design xxx (2010) xxx­xxx Contents lists

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

    SciTech Connect (OSTI)

    B. Olinger

    2005-04-15

    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.

  16. 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,...

  17. The red extended structure of IC10, the nearest blue compact galaxy

    E-Print Network [OSTI]

    Gerbrandt, Stephanie A N; Irwin, Mike

    2015-01-01

    The Local Group starburst galaxy IC10 is the closest example of a blue compact galaxy. Here, we use optical gi imaging from CFHT/MegaCam and near infra-red JHK imaging from UKIRT/WFCAM to conduct a comprehensive survey of the structure of IC10. We examine the spatial distribution of its resolved young, intermediate and old stellar populations to large radius and low effective surface brightness levels. Akin to other dwarfs with multiple populations of different ages, stellar populations of decreasing average age are increasingly concentrated in this galaxy. We find that the young, star-bursting population, and the AGB population, are both offset from the geometric center of the older RGB population by a few hundred parsecs, implying that the younger star formation occurred significantly away from the center of the galaxy. The RGB population traces an extended structure that is typical of blue compact galaxies, with an effective radius of ~5.75 arcmins (~1.25 kpc). These measurements show that IC10 is much mor...

  18. Dozens of compact and high dispersion early-type galaxies in Sloan Digital Sky Survey

    E-Print Network [OSTI]

    Saulder, Christoph; Mieske, Steffen

    2015-01-01

    Aims. We aim at finding candidates of potential survivors of high-redshift compact galaxies in SDSS, as targets for more detailed follow-up observations. Methods. From the virial theorem it is expected that for a given mass, compact galaxies have stellar velocity dispersion higher than the mean due to their smaller sizes. Therefore velocity dispersion coupled with size (or mass) is an appropriate method to select relics, independent of the stellar population properties. Based on these consideration we design a set of criteria using distribution of early-type galaxies from SDSS on the log$_{10}$(R$_{0}$)-log$_{10}$($\\sigma_{0}$) plane to find the most extreme objects on it. Results. We find 76 galaxies at 0.05 < z < 0.2, which have properties similar to the typical quiescent galaxies at high redshift. We study how well these galaxies fit on well-known local universe relations of early-type galaxies such as the fundamental plane, the red sequence or mass-size relations. As expected from the selection crit...

  19. Modular Coil Design for the Ultra-low Aspect Ratio Quasi-axially Symmetric Stellarator MHH2

    SciTech Connect (OSTI)

    Ku LP, the ARIES-CS Team

    2005-09-27

    A family of two field-period quasi-axisymmetric stellarators generally known as MHH2 with aspect ratios of only {approx}2.5 was found. These configurations have low field ripples and excellent confinement of {alpha} particles. This discovery raises the hope that a compact stellarator reactor may eventually be designed with the property of tokamak transport and stellarator stability. In this paper we demonstrate that smooth modular coils may be designed for this family of configurations that not only yield plasmas with good physics properties but also possess engineering properties desirable for compact power producing reactors. We show designs featuring 16 modular coils with ratios of major radius to minimum coil-plasma separation {approx}5.5, major radius to minimum coil-coil separation {approx}10 and the maximum field in coil bodies to the field on axis {approx}2 for 0.2 m{sup 2} conductors. These coils is expected to allow plasmas operated at 5% {beta} with {alpha} energy loss < 10% for a reactor of major radius <9 m at 5 T.

  20. 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

    2015-01-01

    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...

  1. Compact binary mergers as the origin of r-process elements in the Galactic halo

    SciTech Connect (OSTI)

    Ishimaru, Yuhri [Department of Material Science, International Christian University, 3-10-2 Osawa, Mitaka, Tokyo 181-8585 (Japan); Wanajo, Shinya [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Prantzos, Nikos [Institut d'Astrophysique de Paris, UMR7095 CNRS, Univ. P. and M. Curie, 98bis Bd. Arago, 75104 Paris (France)

    2014-05-02

    Compact binary mergers (of double neutron star and black hole-neutron star systems) are suggested to be the major site of the r-process elements in the Galaxy by recent hydrodynamical and nucleosynthesis studies. It has been pointed out, however, that estimated long lifetimes of compact binaries are in conflict with the presence of r-process-enhanced stars at the metallicity [Fe/H] ? ?3. To resolve this problem, we examine the role of compact binary mergers in the early Galactic chemical evolution on the assumption that our Galactic halo was formed from merging sub-halos. The chemical evolutions are modeled for sub-halos with their total stellar masses between 10{sup 4}M{sub ?} and 2 × 10{sup 8}M{sub ?}. The lifetimes of compact binaries are assumed to be 100 Myr (95%) and 1 Myr (5%) according to recent binary population synthesis studies. We find that the r-process abundances (relative to iron; [r/Fe]) start increasing at [Fe/H] ? ?3 if the star formation rates are smaller for less massive sub-halos. Our models also suggest that the star-to-star scatter of [r/Fe]'s observed in Galactic halo stars can be interpreted as a consequence of greater gas outflow rates for less massive sub-halos. In addition, the sub-solar [r/Fe]'s (observed as [Ba/Fe] ? ?1.5 for [Fe/H] < ?3) are explained by the contribution from the short-lived (? 1 Myr) binaries. Our result indicates, therefore, that compact binary mergers can be potentially the origin of the r-process elements throughout the Galactic history.

  2. ULTRA-COMPACT DWARFS IN THE COMA CLUSTER

    SciTech Connect (OSTI)

    Chiboucas, Kristin; Tully, R. Brent; Marzke, R. O.; Phillipps, S.; Price, J.; Peng, Eric W.; Trentham, Neil; Carter, David; Hammer, Derek E-mail: tully@ifa.hawaii.edu E-mail: S.Phillipps@bristol.ac.uk E-mail: peng@pku.edu.cn E-mail: dxc@astro.livjm.ac.uk

    2011-08-20

    We have undertaken a spectroscopic search for ultra-compact dwarf galaxies (UCDs) in the dense core of the dynamically evolved, massive Coma cluster as part of the Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) Coma Cluster Treasury Survey. UCD candidates were initially chosen based on color, magnitude, degree of resolution within the ACS images, and the known properties of Fornax and Virgo UCDs. Follow-up spectroscopy with Keck/Low-Resolution Imaging Spectrometer confirmed 27 candidates as members of the Coma cluster, a success rate >60% for targeted objects brighter than M{sub R} = -12. Another 14 candidates may also prove to be Coma members, but low signal-to-noise spectra prevent definitive conclusions. An investigation of the properties and distribution of the Coma UCDs finds these objects to be very similar to UCDs discovered in other environments. The Coma UCDs tend to be clustered around giant galaxies in the cluster core and have colors/metallicity that correlate with the host galaxy. With properties and a distribution similar to that of the Coma cluster globular cluster population, we find strong support for a star cluster origin for the majority of the Coma UCDs. However, a few UCDs appear to have stellar population or structural properties which differentiate them from the old star cluster populations found in the Coma cluster, perhaps indicating that UCDs may form through multiple formation channels.

  3. Stellar abundances of beryllium and CUBES

    E-Print Network [OSTI]

    Smiljanic, R

    2014-01-01

    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.

  4. Electron capture cross sections for stellar nucleosynthesis

    E-Print Network [OSTI]

    P. G. Giannaka; T. S. Kosmas

    2015-02-25

    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.

  5. A CMOS-compatible compact display

    E-Print Network [OSTI]

    Chen, Andrew R. (Andrew Raymond)

    2005-01-01

    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 ...

  6. Steady state compact toroidal plasma production

    DOE Patents [OSTI]

    Turner, William C. (Livermore, CA)

    1986-01-01

    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.

  7. 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. ...

  8. Pharmaceutical tablet compaction : product and process design

    E-Print Network [OSTI]

    Pore, Mridula

    2009-01-01

    This thesis explores how tablet performance is affected by microstructure, and how microstructure can be controlled by selection of excipients and compaction parameters. A systematic strategy for formulation and process ...

  9. Compact reflective imaging spectrometer utilizing immersed gratings

    DOE Patents [OSTI]

    Chrisp, Michael P. (Danville, CA)

    2006-05-09

    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.

  10. Compact Picture in Extended Superconformal Field Theories

    E-Print Network [OSTI]

    Dimitar Nedanovski

    2015-10-20

    There is a complex conformal transformation, which maps the $D$ - dimensional real Minkowski space on a bounded set in the $D$ - dimensional complex vector space. It generalizes the Cayley map from $D=1$ dimensions to higher space-time dimensions. This transformation provides a very convenient coordinate picture for Conformal Field Theories called compact picture. In this paper we extend the compact picture coordinates for superconformal field theories in four space-time dimensions.

  11. Technology Selections for Cylindrical Compact Fabrication

    SciTech Connect (OSTI)

    Jeffrey A. Phillips

    2010-10-01

    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.

  12. 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

    2010-02-15

    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.

  13. THE RATIONAL COHOMOLOGY OF A p-LOCAL COMPACT GROUP

    E-Print Network [OSTI]

    Oliver, Bob

    . Classifying space, p-completion, p-local compact group* *s, fusion. C. Broto is partially supported THE RATIONAL COHOMOLOGY OF A p-LOCAL COMPACT GROUP* *aces of compact Lie groups and p-compact groups, and generalises the earlier concept* * of p

  14. in tokamaks and stellarators Nils P. Basse

    E-Print Network [OSTI]

    Basse, Nils Plesner

    Alcator C-Mod Turbulence in tokamaks and stellarators Nils P. Basse MIT Plasma Science and Fusion #12;Alcator C-Mod The plasma monster #12;Alcator C-Mod · Alcator C-Mod tokamak · L- to EDA H-ModAlcator C-Mod tokamak Alcator C-Mod is a divertor tokamak with high magnetic field capability (Bt § 8 T

  15. 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)

    2014-02-01

    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.

  16. Modular stellarator reactor conceptual design study

    SciTech Connect (OSTI)

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

    1983-01-01

    A conceptual design study of the Modular Stellarator Reactor is summarized. The physics basis of the approach is elucidated with emphasis on magnetics performance optimization. Key engineering features of the fusion power core are described. Comparisons with an analogous continuous-helical-coil (torsatron) system are made as the basis of a technical and economic assessment.

  17. Fusion cycles in stars and stellar neutrinos

    E-Print Network [OSTI]

    G. Wolschin

    2002-10-01

    Starting from the early works by Weizsaecker and Bethe about fusion cycles and energy conversion in stars, a brief survey of thermonuclear processes in stars leading to contemporary research problems in this field is given. Special emphasis is put on the physics of stellar and, in particular, solar neutrinos which is at the frontline of current investigations.

  18. Fusion cycles in stars and stellar neutrinos

    E-Print Network [OSTI]

    Wolschin, G

    2003-01-01

    Starting from the early works by Weizsaecker and Bethe about fusion cycles and energy conversion in stars, a brief survey of thermonuclear processes in stars leading to contemporary research problems in this field is given. Special emphasis is put on the physics of stellar and, in particular, solar neutrinos which is at the frontline of current investigations.

  19. 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

  20. Stellar Atmospheres, Ht 2007 Problem Set 1

    E-Print Network [OSTI]

    Korn, Andreas

    Stellar Atmospheres, Ht 2007 Problem Set 1 Due date: Monday, 24 September 2007 at 10.15 1. LTE of how temperature is defined. (b) Where in the solar atmosphere would you expect the strongest for the photosphere? (c) How does the relation between matter and radiation differ between LTE and NLTE? What must

  1. Helical axis stellarator with noninterlocking planar coils

    DOE Patents [OSTI]

    Reiman, A.; Boozer, A.H.

    1984-03-06

    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.

  2. THE STELLAR CONTENT OF OBSCURED GALACTIC GIANT H II REGIONS....

    Office of Scientific and Technical Information (OSTI)

    Journal Article: THE STELLAR CONTENT OF OBSCURED GALACTIC GIANT H II REGIONS. VII. W3 Citation Details In-Document Search Title: THE STELLAR CONTENT OF OBSCURED GALACTIC GIANT H II...

  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

    2015-01-01

    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. DISCRETE MODELS FOR THE p-LOCAL HOMOTOPY THEORY OF COMPACT LIE GROUPS AND p-COMPACT GROUPS

    E-Print Network [OSTI]

    Oliver, Bob

    . Secondary 55R40, 57T1* *0. Key words and phrases. Classifying space, p-completion, fusion, compact Lie g DISCRETE MODELS FOR THE p-LOCAL HOMOTOPY THEORY OF COMPACT LIE GROUPS AND p-COMPACT a certain class of spaces which includes p-* *completed classifying spaces of compact Lie groups

  5. Scaling laws of solar and stellar flares

    E-Print Network [OSTI]

    Markus J. Aschwanden; Robert A. Stern; Manuel Güdel

    2007-10-12

    In this study we compile for the first time comprehensive data sets of solar and stellar flare parameters, including flare peak temperatures T_p, flare peak volume emission measures EM_p, and flare durations t_f from both solar and stellar data, as well as flare length scales L from solar data. Key results are that both the solar and stellar data are consistent with a common scaling law of EM_p ~ T_p^4.7, but the stellar flares exhibit ~250 times higher emission measures (at the same flare peak temperature). For solar flares we observe also systematic trends for the flare length scale L(T_p) ~ T_p^0.9 and the flare duration t_F(T_p) ~ T_p^0.9 as a function of the flare peak temperature. Using the theoretical RTV scaling law and the fractal volume scaling observed for solar flares, i.e., V(L) ~ L^2.4, we predict a scaling law of EM_p ~ T_p^4.3, which is consistent with observations, and a scaling law for electron densities in flare loops, n_p ~ T_p^2/L ~ T_p^1.1. The RTV-predicted electron densities were also found to be consistent with densities inferred from total emission measures, n_p=(EM_p/q_V*V)^1/2, using volume filling factors of q_V=0.03-0.08 constrained by fractal dimensions measured in solar flares. Our results affect also the determination of radiative and conductive cooling times, thermal energies, and frequency distributions of solar and stellar flare energies.

  6. Fluctuations and Energy Balance in Solar and Stellar Dynamos

    E-Print Network [OSTI]

    Ossendrijver, Mathieu

    Fluctuations and Energy Balance in Solar and Stellar Dynamos #12;How countless are your works HAAG Ossendrijver, Antonius Joannes Hendrikus Fluctuations and energy balance in solar and stellar-393-1345-8 #12;Fluctuations and Energy Balance in Solar and Stellar Dynamos Fluctuaties en energiebalans in zonne

  7. Strategy Guideline: Compact Air Distribution Systems

    SciTech Connect (OSTI)

    Burdick, A.

    2013-06-01

    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.

  8. PKS B1718-649: an HI and H2 perspective on the birth of a compact radio source

    E-Print Network [OSTI]

    Maccagni, F M; Morganti, R; Oosterloo, T A; Oonk, J B R; Emonts, B H C

    2015-01-01

    We present neutral hydrogen (HI) and warm molecular hydrogen (H2) observations of the young (10^2 years) radio galaxy PKS B1718-649. We study the morphology and the kinematics of both gas components, focusing, in particular, on their properties in relation to the triggering of the radio activity. The regular kinematics of the large scale HI disk, seen in emission, suggests that an interaction event occurred too long ago to be responsible for the recent triggering of the radio activity. In absorption, we detect two absorption lines along the narrow line of sight of the compact (rHI and of the stellar ...

  9. 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)

    1998-01-01

    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.

  10. Low Luminosity Activity in Hickson Compact Groups

    E-Print Network [OSTI]

    M. A. Martinez; A. del Olmo; J. Perea; R. Coziol

    2006-11-02

    With the aim of studying the influence of environment on the nuclear activity of galaxies, we have selected a well defined sample of 65 Compact Groups of galaxies with concordant redshift in the Hickson Catalog. In this proceeding, we present the results of the classification of nuclear activity for 42 galaxies, based on newly obtained spectral observations. In this subsample, 71% of the galaxies turned out to have emission lines in their nuclei. 73% of these emission-line galaxies were found to have characteristics consistent with low luminosity AGN (LLAGN), which makes compact groups extremely rich in such objects.

  11. Momentum compaction and phase slip factor

    SciTech Connect (OSTI)

    Ng, K.Y.; /Fermilab

    2010-10-01

    Section 2.3.11 of the Handbook of Accelerator Physics and Engineering on Landau damping is updated. The slip factor and its higher orders are given in terms of the various orders of the momentum compaction. With the aid of a simplified FODO lattice, formulas are given for the alteration of the lower orders of the momentum compaction by various higher multipole magnets. The transition to isochronicity is next demonstrated. Formulas are given for the extraction of the first three orders of the slip factor from the measurement of the synchrotron tune while changing the rf frequency. Finally bunch-length compression experiments in semi-isochronous rings are reported.

  12. Remote vacuum compaction of compressible hazardous waste

    DOE Patents [OSTI]

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

    1998-10-06

    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.

  13. Disc formation from stellar tidal disruptions

    E-Print Network [OSTI]

    Bonnerot, Clément; Lodato, Giuseppe; Price, Daniel J

    2015-01-01

    The potential of tidal disruption of stars to probe otherwise quiescent supermassive black holes cannot be exploited, if their dynamics is not fully understood. So far, the observational appearance of these events has been commonly derived from analytical extrapolations of the debris dynamical properties just after the stellar disruption. In this paper, we perform hydrodynamical simulations of stars in highly eccentric orbits, that follow the stellar debris after disruption and investigate their ultimate fate. We demonstrate that gas debris circularize on an orbital timescale because relativistic apsidal precession causes the stream to self-cross. The higher the eccentricity and/or the deeper the encounter, the faster is the circularization. If the internal energy deposited by shocks during stream self-interaction is readily radiated, the gas forms a narrow ring at the circularization radius. It will then proceed to accrete viscously at a super-Eddington rate, puffing up under radiation pressure. If instead c...

  14. Modular stellarator reactor: a fusion power plant

    SciTech Connect (OSTI)

    Miller, R.L.; Bathke, C.G.; Krakowski, R.A.; Heck, F.M.; Green, L.; Karbowski, J.S.; Murphy, J.H.; Tupper, R.B.; DeLuca, R.A.; Moazed, A.

    1983-07-01

    A comparative analysis of the modular stellarator and the torsatron concepts is made based upon a steady-state ignited, DT-fueled, reactor embodiment of each concept for use as a central electric-power station. Parametric tradeoff calculations lead to the selection of four design points for an approx. 4-GWt plant based upon Alcator transport scaling in l = 2 systems of moderate aspect ratio. The four design points represent high-aspect ratio. The four design points represent high-(0.08) and low-(0.04) beta versions of the modular stellarator and torsatron concepts. The physics basis of each design point is described together with supporting engineering and economic analyses. The primary intent of this study is the elucidation of key physics and engineering tradeoffs, constraints, and uncertainties with respect to the ultimate power reactor embodiment.

  15. Theoretical stellar models for old galactic clusters

    E-Print Network [OSTI]

    V. Castellani; S. Degl'Innocenti; M. Marconi

    1998-12-05

    We present new evolutionary stellar models suitable for old Population I clusters, discussing both the consequences of the most recent improvements in the input physics and the effect of element diffusion within the stellar structures. Theoretical cluster isochrones are presented, covering the range of ages from 1 to 9 Gyr for the four selected choices on the metallicity Z= 0.007, 0.010, 0.015 and 0.020. Theoretical uncertainties on the efficiency of superadiabatic convection are discussed in some details. Isochrone fitting to the CM diagrams of the two well observed galactic clusters NGC2420 and M67 indicates that a mixing length parameter alpha = 1.9 appears adequate for reproducing the observed color of cool giant stars. The problems in matching theoretical preditions to the observed slope of MS stars are discussed.

  16. Dynamical Modelling of Hot Stellar Systems

    E-Print Network [OSTI]

    David Merritt

    1995-10-30

    Estimation of the distribution function f and potential Phi of hot stellar systems from kinematical data is discussed. When the functional forms of f and Phi are not specified a priori, accurate estimation of either function requires very high quality data: either accurate ``line profiles'' at radii extending well beyond an effective radius, or large samples of discrete radial velocities. Estimates of Phi(r) based on much smaller data sets can be very strongly influenced by assumptions, explicit or implicit, about the form of f. The importance of casting the estimation problem into a mathematically determined form is stressed. Some techniques for nonparametric estimation are presented, with some preliminary results of their application to real stellar systems.

  17. Thermalisation of electrons in a stellar atmosphere

    E-Print Network [OSTI]

    L. Chevallier

    2006-01-23

    We are interested in electrons kinetics in a stellar atmosphere to validate or invalidate the usually accepted hypothesis of thermalisation of electrons. For this purpose, we calculate the velocity distribution function of electrons by solving the kinetic equation of these particles together with the equations of radiative transfer and statistical equilibrium. We note that this distribution can deviate strongly from a Maxwell-Boltzmann distribution if non-LTE effects are important. Some results and astrophysical consequences are examined.

  18. WFPC2 Stellar Photometry with HSTphot

    E-Print Network [OSTI]

    Andrew E. Dolphin

    2000-06-15

    HSTphot, a photometry package designed to handle the undersampled PSFs found in WFPC2 images, is introduced and described, as well as some of the considerations that have to be made in order to obtain accurate PSF-fitting stellar photometry with WFPC2 data. Tests of HSTphot's internal reliability are made using multiple observations of the same field, and tests of external reliability are made by comparing with DoPHOT reductions of the same data.

  19. Stellarator approach to toroidal plasma confinement

    SciTech Connect (OSTI)

    Johnson, J.L.

    1981-12-01

    An overview is presented of the development and current status of the stellarator approach to controlled thermonuclear confinement. Recent experimental, theoretical, and systems developments have made this concept a viable option for the evolution of the toroidal confinement program. Some experimental study of specific problems associated with departure from two-dimensional symmetry must be undertaken before the full advantages and opportunities of steady-state, net-current-free operation can be realized.

  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)

    2014-11-15

    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. Vacuum magnetic field mapping experiments for validated determination of the helical field coil location in stellarators

    SciTech Connect (OSTI)

    Peterson, J.; Hanson, J.; Hartwell, G.; Knowlton, S. [Department of Physics, Auburn University, Auburn, Alabama 36849 (United States)

    2010-03-15

    Understanding the behavior of plasmas in magnetic confinement fusion devices typically requires accurate knowledge of the magnetic field structure. In stellarator-type confinement devices, the helical magnetic field is produced by currents in external coils and may be traced experimentally in the absence of plasma through the experimental technique of vacuum magnetic field mapping. Field mapping experiments, such as these, were performed on the recently constructed compact toroidal hybrid to verify the range of accessible magnetic configurations, compare the actual magnetic configuration with the design configuration, and identify any vacuum field errors that lead to perturbations of the vacuum magnetic flux surfaces. Furthermore, through the use of a new coil optimization routine, modifications are made to the simulation coil model such that better agreement exists between the experimental and simulation results. An outline of the optimization procedure is discussed in conjunction with the results of one such optimization process performed on the helical field coil.

  2. The Stellar Imager (SI) Vision Mission

    E-Print Network [OSTI]

    Kenneth G. Carpenter; Carolus J. Schrijver; Margarita Karovska; SI Vision Mission Team

    2006-06-16

    The Stellar Imager (SI) is a UV-Optical, Space-Based Interferometer designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and of the Universe in general and asteroseismic imaging of stellar interiors. SI is identified as a "Flagship and Landmark Discovery Mission" in the 2005 Sun Solar System Connection (SSSC) Roadmap and as a candidate for a "Pathways to Life Observatory" in the Exploration of the Universe Division (EUD) Roadmap (May, 2005). SI will revolutionize our view of many dynamic astrophysical processes: its resolution will transform point sources into extended sources, and snapshots into evolving views. SI's science focuses on the role of magnetism in the Universe, particularly on magnetic activity on the surfaces of stars like the Sun. SI's prime goal is to enable long-term forecasting of solar activity and the space weather that it drives. SI will also revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magneto-hydrodynamically controlled processes in the Universe. The results of the SI "Vision Mission" Study are presented in this paper. Additional information on the SI mission concept and related technology development can be found at URL: http://hires.gsfc.nasa.gov/si/.

  3. FODO-Supercell Based Compact Ring Design with Tunable Momentum Compaction and Optimized Dynamic Aperture

    SciTech Connect (OSTI)

    Sun, Yipeng; /SLAC

    2012-05-11

    A storage ring with tunable momentum compaction has the advantage in achieving different RMS bunch length with similar RF capacity, which is potentially useful for many applications, such as linear collider damping ring and pre-damping ring where injected beam has a large energy spread and a large transverse emittance. A tunable bunch length also makes the commissioning and fine tuning easier in manipulating the single bunch instabilities. In this paper, a compact ring design based on a supercell is presented, which achieves a tunable momentum compaction while maintaining a large dynamic aperture.

  4. Recent progress in siting low-level waste disposal facilities in the Southwestern Compact and the Central Interstate Compact

    SciTech Connect (OSTI)

    DeOld, J.H.; Shaffner, J.A.

    1995-11-01

    US Ecology is the private contractor selected to develop and operate low-level waste disposal facilities in the Southwestern and the Central Interstate Compacts. These initiatives have been proceeding for almost a decade in somewhat different regulatory and political climates. This paper chronicles recent events in both projects. In both cases there is reason for continued optimism that low-level waste facilities to serve the needs of waste generators in these two compacts will soon be a reality. When the California Department of Health Services issued a license for the proposed Ward Valley LLRW disposal facility on September 16, 1993, it represented a significant step in implementation of a new generation of regional LLRW disposal facilities. While limited scope land transfer hearings were on the horizon, project beneficiaries were confident that the disposal site would be operational by 1995. Since then, however, political initiatives championed by Senator Barbara Boxer (D-CA) have clouded the federal land transfer process and left the commencement date of operations indeterminant. Since 1993, the biomedical community, waste generators most affected by delays, have been petitioning the current administration to emphasize the need for a timely solution. These efforts are aimed at Clinton administration officials responsible for current delays, who apparently have not recognized the importance of the Ward Valley facility to California`s economy, nor the national ramifications of their delaying actions. The current status of challenges to the Ward Valley license and California Environmental Quality Act (CEQA) documentation is also provided. The presentation also discusses the recently completed National Academy of Science evaluation of reports critical of the Ward Valley development process.

  5. HARMONIC TWOSPHERES IN COMPACT SYMMETRIC SPACES, REVISITED

    E-Print Network [OSTI]

    Bath, University of

    HARMONIC TWO­SPHERES IN COMPACT SYMMETRIC SPACES, REVISITED F. E. Burstall and M. A. Guest Introduction The purpose of this article is to give a new description of harmonic maps from the two­sphere S 2 of such harmonic maps occur when G=K = S n or CP n . In 1967, E. Calabi gave a construction of all harmonic maps

  6. REVIEW ARTICLE Principles and applications of compact

    E-Print Network [OSTI]

    Loss, Daniel

    accelerators, a longitudinal accelerating electric field is generated by the ponderomotive forceREVIEW ARTICLE Principles and applications of compact laser­plasma accelerators Rapid progress of fundamental interest in their own right, these interactions enable the generation of high-energy particle

  7. Compact discrete-time chaos generator circuit

    E-Print Network [OSTI]

    Dudek, Piotr

    Compact discrete-time chaos generator circuit P. Dudek and V.D. Juncu A three-transistor CMOS circuit is presented, with adjustable nonlinear characteristics, which can be used as a map that generates discrete-time chaotic signals. A method of constructing a chaos generator using two map circuits is also

  8. Compact range for variable-zone measurements

    DOE Patents [OSTI]

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

    1988-01-01

    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.

  9. 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

    2015-01-01

    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.

  10. Key Features: -Handheld portability, compact rugged design

    E-Print Network [OSTI]

    -touch recording - User configurable, high contrast OLED display - Solid state SD and SDHC card recording media flashcard media in either PCM (.WAV) or MP3 audio formats. The light weight compact form (just 62 x 102 x 25 illuminating, record button. A high contrast, low power draw organic LED (OLED) screen provides vivid display

  11. Compact QED under scrutiny: it's first order

    E-Print Network [OSTI]

    G. Arnold; B. Bunk; Th. Lippert; K. Schilling

    2002-10-07

    We report new results from our finite size scaling analysis of 4d compact pure U(1) gauge theory with Wilson action. Investigating several cumulants of the plaquette energy within the Borgs-Kotecky finite size scaling scheme we find strong evidence for a first-order phase transition and present a high precision value for the critical coupling in the thermodynamic limit.

  12. 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)

    2011-10-15

    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.

  13. 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...

  14. High-frequency behavior of w-mode pulsations of compact stars

    E-Print Network [OSTI]

    Y. J. Zhang; J. Wu; P. T. Leung

    2011-01-01

    We study the asymptotic behavior of the quasi-normal modes (QNMs) of w-mode pulsations of compact stars in the high-frequency regime. We observe that both the axial and polar w-mode QNMs attain similar asymptotic behaviors in spite of the fact that they are described by two totally different differential equation systems. We obtain robust asymptotic formulae relating w-mode QNMs of different polarities and different angular momenta. To explore the physical reason underlying such similarity, we first derive a high-frequency approximation for the polar w-mode oscillations to unify the descriptions for both cases. Then, we develop WKB-type analyses for them and quantitatively explain the observed asymptotic behaviors for polytropic stars and quark stars. We also point out that such asymptotic behaviors for realistic stars are strongly dependent on the equation of state near the stellar surface.

  15. Digging deeper into the Southern skies: a compact Milky-Way companion discovered in first-year Dark Energy Survey data

    E-Print Network [OSTI]

    Luque, E; Santiago, B; Pieres, A; Balbinot, E; Bechtol, K; Drlica-Wagner, A; Neto, A Fausti; da Costa, L N; Maia, M A G; Yanny, B; Abbott, T; Allam, S; Benoit-Lévy, A; Bertin, E; Brooks, D; Buckley-Geer, E; Burke, D L; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Cunha, C E; Desai, S; Diehl, H T; Dietrich, J P; Eifler, T F; Finley, D A; Flaugher, B; Fosalba, P; Frieman, J; Gerdes, D W; Gruen, D; Gutierrez, G; Honscheid, K; James, D J; Kuehn, K; Kuropatkin, N; Lahav, O; Li, T S; March, M; Marshall, J L; Martini, P; Miquel, R; Neilsen, E; Nichol, R C; Nord, B; Ogando, R; Plazas, A A; Romer, A K; Roodman, A; Sanchez, E; Scarpine, V; Schubnell, M; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Thaler, J; Tucker, D; Walker, A R; Zhang, Y

    2015-01-01

    The Dark Energy Survey (DES) is a 5000 sq. degree survey in the southern hemisphere, which is rapidly reducing the existing north-south asymmetry in the census of MW satellites and other stellar substructure. We use the first-year DES data down to previously unprobed photometric depths to search for stellar systems in the Galactic halo, therefore complementing the previous analysis of the same data carried out by our group earlier this year. Our search is based on a matched filter algorithm that produces stellar density maps consistent with stellar population models of various ages, metallicities, and distances over the survey area. The most conspicuous density peaks in these maps have been identified automatically and ranked according to their significance and recurrence for different input models. We report the discovery of one additional stellar system besides those previously found by several authors using the same first-year DES data. The object is compact, and consistent with being dominated by an old a...

  16. Adjoint and Compensated Compactness Methods for Hamilton–Jacobi PDE

    E-Print Network [OSTI]

    Evans, Lawrence C.

    2010-01-01

    Compactness Methods for Hamilton–Jacobi PDE Lawrence C.Compactness Methods of the Hamilton–Jacobi equation u t +Jacobi PDE with nonconvex Hamiltonians, and present a new method

  17. PRODUCTS OF COMPACT SPACES AND THE AXIOM OF CHOICE ...

    E-Print Network [OSTI]

    1910-20-32

    Mar 4, 2002 ... Yj. Clearly Qv is compact A. The product Q = ? v??. Qv is a compact A ..... The function Q ?? iQ may not be in N, however the set f1 defined ...

  18. NGC 3628-UCD1: A possible $\\omega$ Cen Analog Embedded in a Stellar Stream

    E-Print Network [OSTI]

    Jennings, Zachary G; Brodie, Jean P; Janz, Joachim; Norris, Mark A; Forbes, Duncan A; Martinez-Delgado, David; Fagioli, Martina; Penny, Samantha J

    2015-01-01

    Using Subaru/Suprime-Cam wide-field imaging and both Keck/ESI and LBT/MODS spectroscopy, we identify and characterize a compact star cluster, which we term NGC 3628-UCD1, embedded in a stellar stream around the spiral galaxy NGC 3628. The size and luminosity of UCD1 are similar to $\\omega$ Cen, the most luminous Milky Way globular cluster, which has long been suspected to be the stripped remnant of an accreted dwarf galaxy. The object has a magnitude of $i=19.3$ mag (${\\rm L}_{\\rm i}=1.4\\times10^{6}~{\\rm L}_{\\odot}$). UCD1 is marginally resolved in our ground-based imaging, with a half-light radius of $\\sim10$ pc. We measure an integrated brightness for the stellar stream of $i=13.1$ mag, with $(g-i)=1.0$. This would correspond to an accreted dwarf galaxy with an approximate luminosity of ${\\rm L}_i\\sim4.1\\times10^{8}~{\\rm L}_{\\odot}$. Spectral analysis reveals that UCD1 has an age of $6.6$ Gyr , $[\\rm{Z}/\\rm{H}]=-0.75$, an $[{\\alpha}/\\rm{Fe}]=-0.10$. We propose that UCD1 is an example of an $\\omega$ Cen-like...

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

    SciTech Connect (OSTI)

    Fong, W.; Berger, E.

    2013-10-10

    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)

  20. Prospects for pilot plants based on the tokamak, spherical tokamak and stellarator.

    SciTech Connect (OSTI)

    Menard, J. E. [Princeton Plasma Physics Laboratory (PPPL); Bromberg, L. [Massachusetts Institute of Technology (MIT); Brown, T. [Princeton Plasma Physics Laboratory (PPPL); Burgess, Thomas W [ORNL; Dix, D. [School of Engineering and Applied Sciene, Princeton University, Princeton, NJ, USA; El-GuebalyUniv. Wisco, L. [University of Wisconsin; Gerrity, T. [Massachusetts Institute of Technology (MIT); Goldston, R. J. [Princeton Plasma Physics Laboratory (PPPL); Hawryluk, R. [Princeton Plasma Physics Laboratory (PPPL); Kastner, R. [School of Engineering and Applied Sciene, Princeton University, Princeton, NJ, USA; Kessel, C. [Princeton Plasma Physics Laboratory (PPPL); Malang, S. [Fusion Nuclear Technology Consulting, Germany; Minervini, J. [Massachusetts Institute of Technology (MIT); Neilson, G. H. [Princeton Plasma Physics Laboratory (PPPL); Neumeyer, C. L. [Princeton Plasma Physics Laboratory (PPPL); Prager, S. [Princeton Plasma Physics Laboratory (PPPL); Sawan, M. [University of Wisconsin; Sheffield, J. [Inistitute for a Secure and Sustainable Environment, University of Tennessee, Knoxville, TN, USA; Sternlieb, A. [Israel Ministry of Defense, Tel Aviv, Israel; Waganer, L. [Consultant; Whyte, D. G. [Massachusetts Institute of Technology (MIT); Zarnstorff, M. C. [Princeton Plasma Physics Laboratory (PPPL)

    2011-01-01

    A potentially attractive next-step towards fusion commercialization is a pilot plant, i.e. a device ultimately capable of small net electricity production in as compact a facility as possible and in a configuration scalable to a full-size power plant. A key capability for a pilot-plant programme is the production of high neutron fluence enabling fusion nuclear science and technology (FNST) research. It is found that for physics and technology assumptions between those assumed for ITER and nth-of-a-kind fusion power plant, it is possible to provide FNST-relevant neutron wall loading in pilot devices. Thus, it may be possible to utilize a single facility to perform FNST research utilizing reactor-relevant plasma, blanket, coil and auxiliary systems and maintenance schemes while also targeting net electricity production. In this paper three configurations for a pilot plant are considered: the advanced tokamak, spherical tokamak and compact stellarator. A range of configuration issues is considered including: radial build and blanket design, magnet systems, maintenance schemes, tritium consumption and self-sufficiency, physics scenarios and a brief assessment of research needs for the configurations.

  1. A thermodynamic approach for compaction of asphaltic composites 

    E-Print Network [OSTI]

    Koneru, Saradhi

    2009-05-15

    Binder . . . . . . . . . . . . . . . . . . . 8 C. Compaction Equipment . . . . . . . . . . . . . . . . . . . . 9 1. Field Compaction Equipment . . . . . . . . . . . . . . 9 a. Static Steel Wheel Rollers . . . . . . . . . . . . . 9 b. Pneumatic Tire... the desired density level and meet the specifications ? To provide the roadway with a smooth surface. The compaction equipment can be divided into three general categories; static steel wheel rollers, pneumatic tire rollers, and vibratory steel wheel rollers...

  2. Approximating Radon measures on first--countable compact spaces

    E-Print Network [OSTI]

    Plebanek, Grzegorz

    Approximating Radon measures on first--countable compact spaces Grzegorz Plebanek (Wroc/law) Abstract The assertion every Radon measure defined on a first--countable compact space is uniformly regular under CH. In this note we consider some properties of finite Radon measures defined on compact spaces

  3. MODELLING OF CAVITY RECEIVER HEAT TRANSFER COMPACT LINEAR FRESNEL REFLECTOR

    E-Print Network [OSTI]

    MODELLING OF CAVITY RECEIVER HEAT TRANSFER FOR THE COMPACT LINEAR FRESNEL REFLECTOR John D Pye receiver for the Compact Linear Fresnel Reflector is presented. Response to changes in ambient temperature equations are provided. 1. BACKGROUND The Compact Linear Fresnel Reflector (CLFR), shown in Figure 1

  4. PPPL Director Stewart Prager to continue to lead the plasma physics...

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

    The team took office shortly after DOE had cancelled PPPL's unfinished National Compact Stellarator Experiment (NCSX) - now known as QUASAR- when construction costs...

  5. U.S. Department of Energy's Plasma Science Center holds third...

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

    on nanoparticles in dusty plasmas. Meeting participants viewed components of the National Compact Stellarator Experiment during a tour of PPPL. (Photo by Elle Starkman, PPPL Office...

  6. Magnetic Field Line Tracing Calculations for Conceptual PFC Design...

    Office of Scientific and Technical Information (OSTI)

    Conference: Magnetic Field Line Tracing Calculations for Conceptual PFC Design in the National Compact Stellarator Experiment Citation Details In-Document Search Title: Magnetic...

  7. Hot Jupiters and stellar magnetic activity

    E-Print Network [OSTI]

    A. F. Lanza

    2008-05-20

    Recent observations suggest that stellar magnetic activity may be influenced by the presence of a close-by giant planet. Specifically, chromospheric hot spots rotating in phase with the planet orbital motion have been observed during some seasons in a few stars harbouring hot Jupiters. The spot leads the subplanetary point by a typical amount of about 60-70 degrees, with the extreme case of upsilon And where the angle is about 170 degrees. The interaction between the star and the planet is described considering the reconnection between the stellar coronal field and the magnetic field of the planet. Reconnection events produce energetic particles that moving along magnetic field lines impact onto the stellar chromosphere giving rise to a localized hot spot. A simple magnetohydrostatic model is introduced to describe the coronal magnetic field of the star connecting its surface to the orbiting planet. The field is assumed to be axisymmetric around the rotation axis of the star and its configuration is more general than a linear force-free field. With a suitable choice of the free parameters, the model can explain the phase differences between the hot spots and the planets observed in HD 179949, upsilon And, HD 189733, and tau Bootis, as well as their visibility modulation on the orbital period and seasonal time scales. The possible presence of cool spots associated with the planets in tau Boo and HD 192263 cannot be explained by the present model. However, we speculate about the possibility that reconnection events in the corona may influence subphotospheric dynamo action in those stars producing localized photospheric (and chromospheric) activity migrating in phase with their planets.

  8. Boxy/Peanut bulges and stellar bars

    E-Print Network [OSTI]

    Martinez-Valpuesta, I

    2008-01-01

    Boxy/peanut bulges in disc galaxies have been associated to stellar bars. We analyse their properties in a large sample of $N$-body simulations, using different methods to measure their strength, shape and possible asymmetry, and then inter-compare the results. Some of these methods can be applied to both simulations and observations. In particular, we seek correlations between bar and peanut properties, which, when applied to real galaxies, will give information on bars in edge-on galaxies, and on peanuts in face-on galaxies.

  9. Boxy/Peanut bulges and stellar bars

    E-Print Network [OSTI]

    Martinez-Valpuesta; I.; Athanassoula; E.

    2008-01-21

    Boxy/peanut bulges in disc galaxies have been associated to stellar bars. We analyse their properties in a large sample of $N$-body simulations, using different methods to measure their strength, shape and possible asymmetry, and then inter-compare the results. Some of these methods can be applied to both simulations and observations. In particular, we seek correlations between bar and peanut properties, which, when applied to real galaxies, will give information on bars in edge-on galaxies, and on peanuts in face-on galaxies.

  10. Planetary nebulae, tracers of stellar nucleosynthesis

    E-Print Network [OSTI]

    Grazyna Stasinska

    2007-08-31

    We review the information that planetary nebulae and their immediate progenitors, the post-AGB objects, can provide to probe the nucleosynthesis and mixing in low and intermediate mass stars. We emphasize new approaches based on high signal-to-noise spectroscopy of planetary nebulae and of their central stars. We mention some of the problems still to overcome. We emphasize that, as found by several authors, planetary nebulae in low metallicity environments cannot be used to probe the oxygen abundance in the interstellar medium out of which their progenitors were formed, because of abundance modification during stellar evolution.

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

    E-Print Network [OSTI]

    Thomas Cokelaer

    2007-09-07

    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.

  12. Estimation and Effects of the mass outflow rate from shock compressed flow around compact objects

    E-Print Network [OSTI]

    Sandip K. Chakrabarti

    1999-10-01

    Outflows are common in many astrophysical systems which contain black holes and neutron stars. Difference between stellar outflows and outflows from these systems is that the outflows in these systems have to form out of the inflowing material only. The inflowing material can form a hot and dense cloud surrounding the compact object, either because of a centrifugal barrier, or a denser barrier due to pair plasma or pre-heating effects. This barrier behaves like a stellar surface as far as the mass loss is concerned. We estimate the outflow rate from the regions of shock compressed flow. The outflow rate is directly related to the compression ratio of the gas at the shocks. These estimated rates roughly match the rates in real observations as well as those obtained from numerical experiments. In special geometries, where the solid angle of the outflow is higher, the disk evacuation takes place creating quiescence states. Outflows are shown to be important in deciding the spectral states and Quasi Periodic Oscillations (QPO)s of observed X-rays.

  13. Tidal deformations of a spinning compact object

    E-Print Network [OSTI]

    Pani, Paolo; Maselli, Andrea; Ferrari, Valeria

    2015-01-01

    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 mom...

  14. Perturbations to Stellar Structure in 2D: Stellar Rotation and Heating in X-ray Binaries

    E-Print Network [OSTI]

    John J. Eldridge; Pascale Garaud; Christopher A. Tout

    2002-09-16

    We have developed a numerical code with which we study the effects of 2D perturbations on stellar structure. We present new numerical and analytical results on the heating of a main-sequence star in a binary system by its companion.

  15. Nucleosynthesis Supernova Explosions Final Stages of Stellar Evolution For Take Away Final Stages of Stellar Evolution

    E-Print Network [OSTI]

    Hörandel, Jörg R.

    Nucleosynthesis Supernova Explosions Final Stages of Stellar Evolution For Take Away Final Stages.XII.2006 Seminar on Astroparticle Physics - Cosmic Rays #12;Nucleosynthesis Supernova Explosions Final are supernova explosions and which different types exist? Where do heavy elements come from? #12;Nucleosynthesis

  16. THE REDSHIFT EVOLUTION OF THE RELATION BETWEEN STELLAR MASS,...

    Office of Scientific and Technical Information (OSTI)

    THE REDSHIFT EVOLUTION OF THE RELATION BETWEEN STELLAR MASS, STAR FORMATION RATE, AND GAS METALLICITY OF GALAXIES Citation Details In-Document Search Title: THE REDSHIFT EVOLUTION...

  17. 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...

  18. Recent Advances in the Design of Quasi-axisymmetric Stellarator...

    Office of Scientific and Technical Information (OSTI)

    Recent Advances in the Design of Quasi-axisymmetric Stellarator Plasma Configurations Citation Details In-Document Search Title: Recent Advances in the Design of Quasi-axisymmetric...

  19. 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

    2015-01-01

    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...

  20. Compact x-ray source and panel

    DOE Patents [OSTI]

    Sampayon, Stephen E. (Manteca, CA)

    2008-02-12

    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.

  1. The Evolution of Compact Binary Star Systems

    E-Print Network [OSTI]

    Konstantin Postnov; Lev Yungelson

    2014-03-21

    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.

  2. Intragroup diffuse light in compact groups of galaxies II. HCG 15, 35 and 51

    E-Print Network [OSTI]

    C. Da Rocha; B. L. Ziegler; C. Mendes de Oliveira

    2008-05-29

    This continuing study of intragroup light in compact groups of galaxies aims to establish new constraints to models of formation and evolution of galaxy groups, specially of compact groups, which are a key part in the evolution of larger structures, such as clusters. In this paper we present three additional groups (HCG 15, 35 and 51) using deep wide field $B$ and $R$ band images observed with the LAICA camera at the 3.5m telescope at the Calar Alto observatory (CAHA). This instrument provides us with very stable flatfielding, a mandatory condition for reliably measuring intragroup diffuse light. The images were analyzed with the OV\\_WAV package, a wavelet technique that allows us to uncover the intragroup component in an unprecedented way. We have detected that 19, 15 and 26% of the total light of HCG 15, 35 and 51, respectively, is in the diffuse component, with colours that are compatible with old stellar populations and with mean surface brightness that can be as low as $28.4 {\\rm B mag arcsec^{-2}}$. Dynamical masses, crossing times and mass to light ratios were recalculated using the new group parameters. Also tidal features were analyzed using the wavelet technique.

  3. Accretion-Powered Stellar Winds II: Numerical Solutions for Stellar Wind Torques

    E-Print Network [OSTI]

    Sean Matt; Ralph E. Pudritz

    2008-01-18

    [Abridged] In order to explain the slow rotation observed in a large fraction of accreting pre-main-sequence stars (CTTSs), we explore the role of stellar winds in torquing down the stars. For this mechanism to be effective, the stellar winds need to have relatively high outflow rates, and thus would likely be powered by the accretion process itself. Here, we use numerical magnetohydrodynamical simulations to compute detailed 2-dimensional (axisymmetric) stellar wind solutions, in order to determine the spin down torque on the star. We explore a range of parameters relevant for CTTSs, including variations in the stellar mass, radius, spin rate, surface magnetic field strength, the mass loss rate, and wind acceleration rate. We also consider both dipole and quadrupole magnetic field geometries. Our simulations indicate that the stellar wind torque is of sufficient magnitude to be important for spinning down a ``typical'' CTTS, for a mass loss rate of $\\sim 10^{-9} M_\\odot$ yr$^{-1}$. The winds are wide-angle, self-collimated flows, as expected of magnetic rotator winds with moderately fast rotation. The cases with quadrupolar field produce a much weaker torque than for a dipole with the same surface field strength, demonstrating that magnetic geometry plays a fundamental role in determining the torque. Cases with varying wind acceleration rate show much smaller variations in the torque suggesting that the details of the wind driving are less important. We use our computed results to fit a semi-analytic formula for the effective Alfv\\'en radius in the wind, as well as the torque. This allows for considerable predictive power, and is an improvement over existing approximations.

  4. INTERMEDIATE-AGE STELLAR POPULATIONS IN CLASSICAL QUASI-STELLAR OBJECT HOST GALAXIES

    SciTech Connect (OSTI)

    Canalizo, Gabriela; Stockton, Alan E-mail: stockton@ifa.hawaii.edu

    2013-08-01

    Although mergers and starbursts are often invoked in the discussion of quasi-stellar object (QSO) activity in the context of galaxy evolution, several studies have questioned their importance or even their presence in QSO host galaxies. Accordingly, we are conducting a study of z {approx} 0.2 QSO host galaxies previously classified as passively evolving elliptical galaxies. We present deep Keck/LRIS spectroscopy of a sample of 15 hosts and model their stellar absorption spectra using stellar synthesis models. The high signal-to-noise ratio of our spectra allows us to break various degeneracies that arise from different combinations of models, varying metallicities, and contamination from QSO light. We find that none of the host spectra can be modeled by purely old stellar populations and that the majority of the hosts (14/15) have a substantial contribution from intermediate-age populations with ages ranging from 0.7 to 2.4 Gyr. An average host spectrum is strikingly well fit by a combination of an old population and a 2.1 (+0.5, -0.7) Gyr population. The morphologies of the host galaxies suggest that these aging starbursts were induced during the early stages of the mergers that resulted in the elliptical-shaped galaxies that we observe. The current active galactic nucleus activity likely corresponds to the late episodes of accretion predicted by numerical simulations, which occur near the end of the mergers, whereas earlier episodes may be more difficult to observe due to obscuration. Our off-axis observations prevent us from detecting any current star formation or young stellar populations that may be present in the central few kiloparsecs.

  5. Stellar convective cores as dark matter probes

    E-Print Network [OSTI]

    Jordi Casanellas; Isa M. Brandão; Yveline Lebreton

    2015-05-06

    The recent detection of a convective core in a main-sequence solar-type star is used here to test particular models of dark matter (DM) particles, those with masses and scattering cross sections in the range of interest for the DM interpretation of the positive results in several DM direct detection experiments. If DM particles do not effectively self-annihilate after accumulating inside low-mass stars (e.g. in the asymmetric DM scenario) their conduction provides an efficient mechanism of energy transport in the stellar core. For main-sequence stars with masses between 1.1 and 1.3 Msun, this mechanism may lead to the suppression of the inner convective region expected to be present in standard stellar evolution theory. The asteroseismic analysis of the acoustic oscillations of a star can prove the presence/absence of such a convective core, as it was demonstrated for the first time with the Kepler field main-sequence solar-like pulsator, KIC 2009505. Studying this star we found that the asymmetric DM interpretation of the results in the CoGeNT experiment is incompatible with the confirmed presence of a small convective core in KIC 2009505.

  6. Observational Tests and Predictive Stellar Evolution

    E-Print Network [OSTI]

    P. A. Young; E. E. Mamajek; David Arnett; James Liebert

    2001-03-23

    We compare eighteen binary systems with precisely determined radii and masses from 23 to 1.1 M_sol, and stellar evolution models produced with our newly revised code TYCHO. ``Overshooting'' and rotational mixing were suppressed in order to establish a baseline for isolating these and other hydrodynamic effects. Acceptable coeval fits are found for sixteen pairs without optimizing for heavy element or helium abundance. The precision of these tests is limited by the accuracies of the observed effective temperatures. High dispersion spectra and detailed atmospheric modeling should give more accurate effective temperatures and heavy element abundances. PV Cas, a peculiar early A system, EK Cep B, a known post-T Tauri star, and RS Cha, a member of a young OB association, are matched by pre-main sequence models. Predicted mass loss agrees with upper limits from IUE for CW Cep A and B. Relatively poor fits are obtained for binaries having at least one component in the mass range 1.7 < M/M_sol <2.6, whose evolution is sensitive to mixing. These discrepancies are robust and consistent with additional mixing in real stars. The predicted apsidal motion implies that massive star models are systematically less centrally condensed than the real stars. If these effects are due to overshooting, then the overshooting parameter alpha_OV increases with stellar mass. The apsidal motion constants are controlled by radiative opacity under conditions close to those directly measured in laser experiments, making this test more stringent than possible before.

  7. Stellar stability in brane-worlds revisited

    E-Print Network [OSTI]

    Miguel A. García-Aspeitia; L. Arturo Ureña-López

    2014-12-28

    We consider here the general conditions for the stability of brane stars that obey a so called a "minimal setup": the nonlocal anisotropic stress and energy flux are everywhere absent, and the only permitted Weyl correction is the interior solution of the nonlocal energy density. Along with a series of simple conditions, we show that the Germani-Maartens solution with a constant density sets up the upper bound for the compactness of that particular class of brane stars. The general demonstration is based upon the properties of the interior solutions of the stars, although we also show that the minimal setup implies a Schwarzschild exterior.

  8. The evolutionary status of the low-metallicity blue compact dwarf galaxy SBS 0940+544

    E-Print Network [OSTI]

    N. G. Guseva; Y. I. Izotov; P. Papaderos; F. H. Chaffee; C. B. Foltz; R. F. Green; T. X. Thuan; K. J. Fricke; K. G. Noeske

    2001-09-17

    We present the results of spectrophotometry and V,R,I, Halpha CCD photometry of the blue compact dwarf (BCD) galaxy SBS 0940+544. Broad-band images taken with the 2.1m KPNO and 1.23m Calar Alto telescopes reveal a compact high-surface-brightness H II region with ongoing star formation, located at the northwestern tip of the elongated low surface brightness (LSB) main body of the BCD. High signal-to-noise 4.5m Multiple Mirror Telescope (MMT) and 10m Keck II telescope long-slit spectroscopy of SBS 0940+544 is used to derive element abundances of the ionized gas in the brightest H II region and to study the stellar population in the host galaxy. The oxygen abundance in the brightest region with strong emission lines is 12+log(O/H) = 7.46-7.50, or 1/29-1/26 solar, in agreement with earlier determinations and among the lowest for BCDs. Hbeta and Halpha emission lines and Hdelta and Hgamma absorption lines are detected in a large part of the main body. Three methods are used to put constraints on the age of the stellar population at different positions along the major axis. They are based on (a) the equivalent widths of the emission lines, (b) the equivalent widths of the absorption lines and (c) the spectral energy distributions (SED). Several scenarios of star formation have been considered. The observed properties in the main body can be reproduced by a continuous star formation process which started not earlier than 100 Myr ago, if a small extinction is assumed. However, the observations can be reproduced equally well by a stellar population forming continuously since 10 Gyr ago, if the star formation rate has increased during the last 100 Myr in the main body of SBS 0940+544 by at least a factor of five. In summary, we find no compelling evidence which favors either a young or an old age of SBS 0940+544.

  9. 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)

    2012-01-20

    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.

  10. Gas Feedback on Stellar Bar Evolution

    E-Print Network [OSTI]

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

    2007-05-27

    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.

  11. 1 IAEA-CN-94/IC-1 Physics Considerations in the Design of NCSX*

    E-Print Network [OSTI]

    Hudson, Stuart

    @pppl.gov Abstract. Compact stellarators have to potential to make a steady-state, disruption-free magnetic fusion on the problem of finding the best magnetic configuration for a practical fusion reactor. Stellarators-symmetry is used to reduce losses. The National Compact Stellarator Experiment is designed to produce a quasi

  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. Development of a compact tomography camera system using a multianode photomultiplier tube for compact torus experiments

    SciTech Connect (OSTI)

    Tomuro, H.; Asai, T.; Iguchi, K.; Takahashi, Ts.; Hirano, Y. [Department of Physics, College of Science and Technology, Nihon University, Tokyo 101-8308 (Japan)

    2010-10-15

    A compact tomography camera system consisting of a photomultiplier tube, a multislit optical system, and a band-pass interference filter has been developed. The viewing area and spatial resolution can be configured by the arrangement of the slit system. The camera system has been specially designed for self-organized compact torus experiments having strong magnetohydrodynamics events with a submicrosecond time-scale. The developed system has been tested on a field-reversed configuration formed by the field-reversed theta-pinch. Performance evaluation of the system has been performed by comparison to the former optical system.

  14. Ratification of interstate compacts for low-level nuclear waste management

    SciTech Connect (OSTI)

    Not Available

    1983-01-01

    Part I of the hearing series covers testimony pertaining to three bills (H.R. 1012, H.R. 3002, and H.R. 3777) granting Congressional consent to the Northwest, Central, and Southeast interstate compacts. Witnesses reviewed the status of the compacts, which would implement the Low-Level Radioactive Waste Policy Act of 1980, and the responses of states, which varying according to whether operating sites already exist in the region. Testimony was given by a panel of representatives from the DOE Office of Terminal Waste Disposal and Remedial Action, the Nuclear Regulatory Commission's Office of Nuclear Material Safety and Safeguards and Office of State Programs, and the National Governors Association's Committee on Energy and Environment. The hearing record includes the tests of the three bills, the testimony, and an appendix with additional material submitted for the record. (DCK)

  15. Thermonuclear inverse magnetic pumping power cycle for stellarator reactor

    DOE Patents [OSTI]

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

    1991-01-01

    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. Stellar properties and nuclear matter constraints

    E-Print Network [OSTI]

    Dutra, Mariana; Menezes, Débora P

    2015-01-01

    We have analyzed stellar properties of the relativistic mean-field (RMF) parametrizations shown to be consistent with the recently studied constraints related to nuclear matter, pure neutron matter, symmetry energy and its derivatives [Dutra et al., Phys. Rev. C 90, 055203 (2014)]. Our results show that only two RMF parametrizations do not allow the emergence of the direct Urca process, important aspect regarding the evolution of a neutron star. Moreover, among all approved RMF models, fourteen of them produce neutron stars with maximum masses inside the range $1.93\\leqslant M/M_\\odot\\leqslant 2.05$, with $M_\\odot$ being the solar mass. Only three models yield maximum masses above this range and a discussion on the inclusion of hyperons is presented. Finally, we have verified that the models satisfying the neutron star maximum mass constraint do not observe the squared sound velocity bound, namely, $v_s^2 < 1/3$, corroborating recent findings.

  17. Electromagnetic Pulse from Final Gravitational Stellar Collapse

    E-Print Network [OSTI]

    P. D. Morley; Ivan Schmidt

    2002-01-30

    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.

  18. Impact compaction of a granular material

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

    Fenton, Gregg; Asay, Blaine; Dalton, Devon

    2015-05-19

    The dynamic behavior of granular materials has importance to a variety of engineering applications. Structural seismic coupling, planetary science, and earth penetration mechanics, are just a few of the application areas. Although the mechanical behavior of granular materials of various types have been studied extensively for several decades, the dynamic behavior of such materials remains poorly understood. High-quality experimental data are needed to improve our general understanding of granular material compaction physics. This study will describe how an instrumented plunger impact system can be used to measure pressure-density relationships for model materials at high and controlled strain rates and subsequentlymore »used for computational modeling.« less

  19. Impact compaction of a granular material

    SciTech Connect (OSTI)

    Fenton, Gregg; Asay, Blaine; Dalton, Devon

    2015-05-19

    The dynamic behavior of granular materials has importance to a variety of engineering applications. Structural seismic coupling, planetary science, and earth penetration mechanics, are just a few of the application areas. Although the mechanical behavior of granular materials of various types have been studied extensively for several decades, the dynamic behavior of such materials remains poorly understood. High-quality experimental data are needed to improve our general understanding of granular material compaction physics. This study will describe how an instrumented plunger impact system can be used to measure pressure-density relationships for model materials at high and controlled strain rates and subsequently used for computational modeling.

  20. Uplifting non-compact gauged supergravities

    E-Print Network [OSTI]

    Walter H. Baron; Gianguido Dall'Agata

    2015-01-19

    We provide the M-theory uplift of de Sitter vacua of SO(5,3) and SO(4,4) gaugings of maximal supergravity in 4 dimensions. We find new non-compact backgrounds that are squashed hyperboloids with non-trivial flux for the 3-form potential. The uplift requires a new non-linear ansatz for the 11-dimensional metric and for the 3-form potential that reduces to the known one leading to the 7-sphere solution in the case of the SO(8) gauging.

  1. Uplifting non-compact gauged supergravities

    E-Print Network [OSTI]

    Baron, Walter H

    2014-01-01

    We provide the M-theory uplift of de Sitter vacua of SO(5,3) and SO(4,4) gaugings of maximal supergravity in 4 dimensions. We find new non-compact backgrounds that are squashed hyperboloids with non-trivial flux for the 3-form potential. The uplift requires a new non-linear ansatz for the 11-dimensional metric and for the 3-form potential that reduces to the known one leading to the 7-sphere solution in the case of the SO(8) gauging.

  2. Casimir Forces between Arbitrary Compact Objects

    SciTech Connect (OSTI)

    Emig, T. [Laboratoire de Physique Theorique et Modeles Statistiques, CNRS UMR 8626, Universite Paris-Sud, 91405 Orsay (France); Graham, N. [Department of Physics, Middlebury College, Middlebury, Vermont 05753 (United States); Center for Theoretical Physics, Laboratory for Nuclear Science, and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Jaffe, R. L. [Center for Theoretical Physics, Laboratory for Nuclear Science, and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Kardar, M. [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2007-10-26

    We develop an exact method for computing the Casimir energy between arbitrary compact objects, either dielectrics or perfect conductors. The energy is obtained as an interaction between multipoles, generated by quantum current fluctuations. The objects' shape and composition enter only through their scattering matrices. The result is exact when all multipoles are included, and converges rapidly. A low frequency expansion yields the energy as a series in the ratio of the objects' size to their separation. As an example, we obtain this series for two dielectric spheres and the full interaction at all separations for perfectly conducting spheres.

  3. Finite size scaling analysis of compact QED

    E-Print Network [OSTI]

    G. Arnold; Th. Lippert; Th. Neuhaus; K. Schilling

    2000-11-13

    We describe results of a high-statistics finite size scaling analysis of 4d compact U(1) lattice gauge theory with Wilson action at the phase transition point. Using a multicanonical hybrid Monte Carlo algorithm we generate data samples with more than 150 tunneling events between the metastable states of the system, on lattice sizes up to 18^4. We performed a first analysis within the Borgs-Kotecky finite size scaling scheme. As a result, we report evidence for a first-order phase transition with a plaquette energy gap, G=0.02667(20), at a transition coupling, beta_T=1.011128(11).

  4. Multicanonical hybrid Monte Carlo for compact QED

    E-Print Network [OSTI]

    G. Arnold; Th. Lippert; K. Schilling

    1999-09-14

    We demonstrate that substantial progress can be achieved in the study of the phase structure of 4-dimensional compact QED by a joint use of hybrid Monte Carlo and multicanonical algorithms, through an efficient parallel implementation. This is borne out by the observation of considerable speedup of tunnelling between the metastable states, close to the phase transition, on the Wilson line. Our approach leads to a general parallelization scheme for the efficient stochastic sampling of systems where (a part of) the Hamiltonian involves the total action or energy in each update step.

  5. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would like submit the following comments responseScienceCommunity RelationsCompact soft

  6. 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 on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION JEnvironmentalBowerbank,CammackFLIR JumpMaine: Energy Resources Jump to:Michigan:Compact Power Ltd

  7. Compact portable electric power sources (Technical Report) |...

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

    Org: Oak Ridge National Lab., TN (United States) Sponsoring Org: USDOE, Washington, DC (United States) Country of Publication: United States Language: English Subject: 24...

  8. Constraints on the Stellar/Sub-stellar Mass Function in the Inner Orion Nebula Cluster

    E-Print Network [OSTI]

    Lynne A. Hillenbrand; John M. Carpenter

    2000-03-20

    We present the results of a 0.5-0.9" FWHM imaging survey at K (2.2 micron) and H (1.6 micron) covering 5.1' x 5.1' centered on Theta 1C Ori, the most massive star in the Orion Nebula Cluster (ONC). At the age and distance of this cluster, and in the absence of extinction, the hydrogen burning limit (0.08 Mo) occurs at K~13.5 mag while an object of mass 0.02 Mo has K~16.2 mag. Our photometry is complete for source detection at the 7 sigma level to K~17.5 mag and thus is sensitive to objects as low-mass as 0.02 Mo seen through visual extinction values as high as 10 magnitudes. We use the observed magnitudes, colors, and star counts to constrain the shape of the inner ONC stellar mass function across the hydrogen burning limit. After determining the stellar age and near-infrared excess properties of the optically visible stars in this same inner ONC region, we present a new technique that incorporates these distributions when extracting the mass function from the observed density of stars in the K-(H-K) diagram. We find that our data are inconsistent with a mass function that rises across the stellar/sub-stellar boundary. Instead, we find that the most likely form of the inner ONC mass function is one that rises to a peak around 0.15 Mo, and then declines across the hydrogen-burning limit with slope N(log M) ~ M^(0.57+/-0.05). We emphasize that our conclusions apply to the inner 0.71 pc x 0.71 pc of the ONC only; they may not apply to the ONC as a whole where some evidence for general mass segregation has been found.

  9. The universal stellar mass-stellar metallicity relation for dwarf galaxies

    SciTech Connect (OSTI)

    Kirby, Evan N.; Bullock, James S.; Cohen, Judith G.; Guhathakurta, Puragra; Gallazzi, Anna

    2013-12-20

    We present spectroscopic metallicities of individual stars in seven gas-rich dwarf irregular galaxies (dIrrs), and we show that dIrrs obey the same mass-metallicity relation as the dwarf spheroidal (dSph) satellites of both the Milky Way and M31: Z{sub ?}?M{sub ?}{sup 0.30±0.02}. The uniformity of the relation is in contradiction to previous estimates of metallicity based on photometry. This relationship is roughly continuous with the stellar mass-stellar metallicity relation for galaxies as massive as M {sub *} = 10{sup 12} M {sub ?}. Although the average metallicities of dwarf galaxies depend only on stellar mass, the shapes of their metallicity distributions depend on galaxy type. The metallicity distributions of dIrrs resemble simple, leaky box chemical evolution models, whereas dSphs require an additional parameter, such as gas accretion, to explain the shapes of their metallicity distributions. Furthermore, the metallicity distributions of the more luminous dSphs have sharp, metal-rich cut-offs that are consistent with the sudden truncation of star formation due to ram pressure stripping.

  10. The Spatial Structure of Young Stellar Clusters. II. Total Young Stellar Populations

    E-Print Network [OSTI]

    Kuhn, Michael A; Feigelson, Eric D

    2015-01-01

    We investigate the intrinsic stellar populations (estimated total numbers of OB and pre-main-sequence stars down to 0.1 Mo) that are present in 17 massive star-forming regions (MSFRs) surveyed by the MYStIX project. The study is based on the catalog of >31,000 MYStIX Probable Complex Members with both disk-bearing and disk-free populations, compensating for extinction, nebulosity, and crowding effects. Correction for observational sensitivities is made using the X-ray Luminosity Function (XLF) and the near-infrared Initial Mass Function (IMF)--a correction that is often not made by infrared surveys of young stars. The resulting maps of the projected structure of the young stellar populations, in units of intrinsic stellar surface density, allow direct comparison between different regions. Several regions have multiple dense clumps, similar in size and density to the Orion Nebula Cluster. The highest projected density of ~34,000 stars/pc^2 is found in the core of the RCW38 cluster. Histograms of surface densit...

  11. Tidal deformations of a spinning compact object

    E-Print Network [OSTI]

    Paolo Pani; Leonardo Gualtieri; Andrea Maselli; Valeria Ferrari

    2015-06-30

    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.

  12. Compact solid source of hydrogen gas

    DOE Patents [OSTI]

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

    2004-06-08

    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.

  13. Radiography to measure the longitudinal density gradients of Pd compacts

    SciTech Connect (OSTI)

    Back, D.D.

    1992-05-14

    This study used radiography to detect and quantify density gradients in green compacts of Palladium powder. Ultrasonic velocity measurements had been tried previously, but they were affected by material properties, in addition to the density, so that an alternative was sought. The alternative technique used radiographic exposures of a series of standard compacts whose density is known and correlated with the radiographic film density. These correlations are used to predict the density in subsequent compacts.

  14. RIEMANN'S INEQUALITY AND RIEMANN-ROCH Fix a compact ...

    E-Print Network [OSTI]

    2013-11-14

    RIEMANN'S INEQUALITY AND RIEMANN-ROCH. DONU ARAPURA. Fix a compact connected Riemann surface X of genus g. Riemann's inequality gives a

  15. Relating Follicly-Challenged Compact Stars to Bald Black Holes

    E-Print Network [OSTI]

    Kent Yagi; Nicolas Yunes

    2015-07-08

    Compact stars satisfy certain no-hair relations through which their multipole moments are given by their mass, spin and quadrupole moment. These relations are approximately independent of their equation of state, relating pressure to density. Such relations are similar to the black hole no-hair theorems, but these possess event horizons inside which information that led to their formation can hide. Compact stars do not possess horizons, so whether their no-hair relations are related to the black hole ones is unclear. We investigate how the two relations are related by studying relations among multipole moments for compact stars with anisotropic pressure as a toy model, which allows such stars to be more compact than those with isotropic pressure. We here show numerically that the compact star no-hair relations approach the black hole ones as the compactness approaches that of a black hole. We also prove analytically that the current dipole moment exactly reaches the black hole limit quadratically in compactness as strongly-anisotropic stars approach the black hole limit. We moreover show that compact stars become progressively oblate in this limit, even if prolate at low compactness due to strong anisotropies.

  16. Green strength of zirconium sponge and uranium dioxide powder compacts

    SciTech Connect (OSTI)

    Balakrishna, Palanki Murty, B. Narasimha; Sahoo, P.K.; Gopalakrishna, T.

    2008-07-15

    Zirconium metal sponge is compacted into rectangular or cylindrical shapes using hydraulic presses. These shapes are stacked and electron beam welded to form a long electrode suitable for vacuum arc melting and casting into solid ingots. The compact electrodes should be sufficiently strong to prevent breakage in handling as well as during vacuum arc melting. Usually, the welds are strong and the electrode strength is limited by the green strength of the compacts, which constitute the electrode. Green strength is also required in uranium dioxide (UO{sub 2}) powder compacts, to withstand stresses during de-tensioning after compaction as well as during ejection from the die and for subsequent handling by man and machine. The strengths of zirconium sponge and UO{sub 2} powder compacts have been determined by bending and crushing respectively, and Weibul moduli evaluated. The green density of coarse sponge compact was found to be larger than that from finer sponge. The green density of compacts from lightly attrited UO{sub 2} powder was higher than that from unattrited category, accompanied by an improvement in UO{sub 2} green crushing strength. The factors governing green strength have been examined in the light of published literature and experimental evidence. The methodology and results provide a basis for quality control in metal sponge and ceramic powder compaction in the manufacture of nuclear fuel.

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

    E-Print Network [OSTI]

    Wada, Keiichi; Saitoh, Takayuki R

    2011-01-01

    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 ...

  18. 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)

    1989-07-01

    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.

  19. 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)

    2014-11-15

    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.

  20. 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.

    2011-05-06

    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.

  1. THE DARK ENERGY SURVEY: PROSPECTS FOR RESOLVED STELLAR POPULATIONS

    SciTech Connect (OSTI)

    Rossetto, Bruno M.; Santiago, Basílio X.; Girardi, Léo; Camargo, Julio I. B.; Balbinot, Eduardo; da Costa, Luiz N.; Yanny, Brian; Maia, Marcio A. G.; Makler, Martin; Ogando, Ricardo L. C.; Pellegrini, Paulo S.; Ramos, Beatriz; de Simoni, Fernando; Armstrong, R.; Bertin, E.; Desai, S.; Kuropatkin, N.; Lin, H.; Mohr, J. J.; Tucker, D. L.

    2011-06-01

    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 108 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.

  2. THE DARK ENERGY SURVEY: PROSPECTS FOR RESOLVED STELLAR POPULATIONS

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

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

    2011-06-01

    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 108 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 themore »Galaxy.« less

  3. A STELLAR WIND ORIGIN FOR THE G2 CLOUD: THREE-DIMENSIONAL NUMERICAL SIMULATIONS

    SciTech Connect (OSTI)

    De Colle, Fabio; Raga, A. C.; Contreras-Torres, Flavio F.; Toledo-Roy, Juan C.

    2014-07-10

    We present three-dimensional, adaptive mesh refinement simulations of G2, a cloud of gas moving in a highly eccentric orbit toward the galactic center. We assume that G2 originates from a stellar wind interacting with the environment of the Sgr A* black hole. The stellar wind forms a cometary bubble which becomes increasingly elongated as the star approaches periastron. A few months after periastron passage, streams of material begin to accrete on the central black hole with accretion rates M-dot ?10{sup ?8} M {sub ?} yr{sup –1}. Predicted Br? emission maps and position-velocity diagrams show an elongated emission resembling recent observations of G2. A large increase in luminosity is predicted by the emission coming from the shocked wind region during periastron passage. The observations, showing a constant Br? luminosity, remain puzzling, and are explained here assuming that the emission is dominated by the free-wind region. The observed Br? luminosity (?8 × 10{sup 30} erg s{sup –1}) is reproduced by a model with a v{sub w} = 50 km s{sup –1} wind velocity and a 10{sup –7} M {sub ?} yr{sup –1} mass-loss rate if the emission comes from the shocked wind. A faster and less dense wind reproduces the Br? luminosity if the emission comes from the inner, free-wind region. The extended cometary wind bubble, largely destroyed by the tidal interaction with the black hole, reforms a few years after periastron passage. As a result, the Br? emission is more compact after periastron passage.

  4. Young Stellar Objects in the Gould Belt

    E-Print Network [OSTI]

    Dunham, Michael M; Evans, Neal J; Broekhoven-Fiene, Hannah; Cieza, Lucas; Di Francesco, James; Gutermuth, Robert A; Harvey, Paul M; Hatchell, Jennifer; Heiderman, Amanda; Huard, Tracy; Johnstone, Doug; Kirk, Jason M; Matthews, Brenda C; Miller, Jennifer F; Peterson, Dawn E; Young, Kaisa E

    2015-01-01

    We present the full catalog of Young Stellar Objects (YSOs) identified in the 18 molecular clouds surveyed by the Spitzer Space Telescope "cores to disks" (c2d) and "Gould Belt" (GB) Legacy surveys. Using standard techniques developed by the c2d project, we identify 3239 candidate YSOs in the 18 clouds, 2966 of which survive visual inspection and form our final catalog of YSOs in the Gould Belt. We compile extinction corrected SEDs for all 2966 YSOs and calculate and tabulate the infrared spectral index, bolometric luminosity, and bolometric temperature for each object. We find that 326 (11%), 210 (7%), 1248 (42%), and 1182 (40%) are classified as Class 0+I, Flat-spectrum, Class II, and Class III, respectively, and show that the Class III sample suffers from an overall contamination rate by background AGB stars between 25% and 90%. Adopting standard assumptions, we derive durations of 0.40-0.78 Myr for Class 0+I YSOs and 0.26-0.50 Myr for Flat-spectrum YSOs, where the ranges encompass uncertainties in the ado...

  5. Stellar Disk Truncations: Where do we stand ?

    E-Print Network [OSTI]

    M. Pohlen; J. E. Beckman; S. Huettemeister; J. H. Knapen; P. Erwin; R. -J. Dettmar

    2004-07-12

    In the light of several recent developments we revisit the phenomenon of galactic stellar disk truncations. Even 25 years since the first paper on outer breaks in the radial light profiles of spiral galaxies, their origin is still unclear. The two most promising explanations are that these 'outer edges' either trace the maximum angular momentum during the galaxy formation epoch, or are associated with global star formation thresholds. Depending on their true physical nature, these outer edges may represent an improved size characteristic (e.g., as compared to D_25) and might contain fossil evidence imprinted by the galaxy formation and evolutionary history. We will address several observational aspects of disk truncations: their existence, not only in normal HSB galaxies, but also in LSB and even dwarf galaxies; their detailed shape, not sharp cut-offs as thought before, but in fact demarcating the start of a region with a steeper exponential distribution of starlight; their possible association with bars; as well as problems related to the line-of-sight integration for edge-on galaxies (the main targets for truncation searches so far). Taken together, these observations currently favour the star-formation threshold model, but more work is necessary to implement the truncations as adequate parameters characterising galactic disks.

  6. Mergers and obliquities in stellar triples

    SciTech Connect (OSTI)

    Naoz, Smadar; Fabrycky, Daniel C.

    2014-10-01

    Many close stellar binaries are accompanied by a faraway star. The 'eccentric Kozai-Lidov' (EKL) mechanism can cause dramatic inclination and eccentricity fluctuations, resulting in tidal tightening of inner binaries of triple stars. We run a large set of Monte Carlo simulations, including the secular evolution of the orbits, general relativistic precession, and tides, and we determine the semimajor axis, eccentricity, inclination, and spin-orbit angle distributions of the final configurations. We find that the efficiency of forming tight binaries (? 16 days) when taking the EKL mechanism into account is ?21%, and about 4% of all simulated systems ended up in a merger event. These merger events can lead to the formation of blue stragglers. Furthermore, we find that the spin-orbit angle distribution of the inner binaries carries a signature of the initial setup of the system; thus, observations can be used to disentangle close binaries' birth configuration. The resulting inner and outer final orbits' period distributions and their estimated fraction suggest that secular dynamics may be a significant channel for the formation of close binaries in triples and even blue stragglers.

  7. Measuring Stellar Limb Darkening by Gravitational Microlensing

    E-Print Network [OSTI]

    David Heyrovsky

    2003-05-19

    Observations of microlensing transit events can be used to measure the limb darkening of the lensed star. We discuss the advantages and drawbacks of several microlensing light curve inversion methods. The method of choice in this work is inversion by means of decomposition of the stellar surface brightness profile. We construct an ideal basis by principal component analysis of brightness profiles obtained from model atmosphere calculations. Limb darkening approximations using such a basis are superior to those using standard power-law limb darkening laws. We perform a full analysis of simulated single-lens microlensing transit events including a detailed error analysis of the method. In realistic events with a low impact parameter the brightness profile of the source can be recovered with a relative accuracy of 2% from the center of the source disk to 0.9 of the disk radius. We show that in the particular case of the observed MACHO Alert 95-30 event the intrinsic complex variability of the lensed red giant hinders efforts to recover its surface features.

  8. 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)

    1996-01-01

    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).

  9. Quantum Chaos in Compact Lattice QED

    E-Print Network [OSTI]

    B. A. Berg; H. Markum; R. Pullirsch

    1998-12-10

    Complete eigenvalue spectra of the staggered Dirac operator in quenched $4d$ compact QED are studied on $8^3 \\times 4$ and $8^3 \\times 6$ lattices. We investigate the behavior of the nearest-neighbor spacing distribution $P(s)$ as a measure of the fluctuation properties of the eigenvalues in the strong coupling and the Coulomb phase. In both phases we find agreement with the Wigner surmise of the unitary ensemble of random-matrix theory indicating quantum chaos. Combining this with previous results on QCD, we conjecture that quite generally the non-linear couplings of quantum field theories lead to a chaotic behavior of the eigenvalues of the Dirac operator.

  10. Quantum chaos in compact lattice QED

    SciTech Connect (OSTI)

    Berg, B.A. [Department of Physics, The Florida State University, Tallahassee, Florida 32306 (United States)] [Department of Physics, The Florida State University, Tallahassee, Florida 32306 (United States); [Supercomputer Computations Research Institute, The Florida State University, Tallahassee, Florida 32306 (United States); Markum, H. [Institut fuer Kernphysik, Technische Universitaet Wien, A-1040 Vienna (Austria)] [Institut fuer Kernphysik, Technische Universitaet Wien, A-1040 Vienna (Austria); Pullirsch, R. [Department of Physics, The Florida State University, Tallahassee, Florida 32306 (United States)] [Department of Physics, The Florida State University, Tallahassee, Florida 32306 (United States); [Institut fuer Kernphysik, Technische Universitaet Wien, A-1040 Vienna (Austria)

    1999-05-01

    Complete eigenvalue spectra of the staggered Dirac operator in quenched 4D compact QED are studied on 8{sup 3}{times}4 and 8{sup 3}{times}6 lattices. We investigate the behavior of the nearest-neighbor spacing distribution P(s) as a measure of the fluctuation properties of the eigenvalues in the strong coupling and the Coulomb phase. In both phases we find agreement with the Wigner surmise of the unitary ensemble of random-matrix theory indicating quantum chaos. Combining this with previous results on QCD, we conjecture that quite generally the non-linear couplings of quantum field theories lead to a chaotic behavior of the eigenvalues of the Dirac operator. {copyright} {ital 1999} {ital The American Physical Society}

  11. Development of compact linear accelerator in KBSI

    SciTech Connect (OSTI)

    Yoon, Jang-Hee; Lee, Byoung-Seob; Choi, Seyong; Park, Jin Yong; Ok, Jung-Woo; Won, Mi-Sook [Busan Center, Korea Basic Science Institute, Busan 609-735 (Korea, Republic of)

    2012-02-15

    The compact linear accelerator using a 28 GHz ECRIS is under construction in KBSI, South Korea. The main capability of this facility is the production of fast neurons for the neutron radiography. The designing of a superconducting magnet, microwave transmission system, beam extraction, and plasma chamber of ECRIS were finished. The nominal axial design fields of the magnets are 3.6 T at injection and 2.2 T at extraction; the nominal radial design field strength at the plasma chamber wall is 2.1 T. We already installed 10 kW, 28 GHz gyrotron, and tested a microwave power from gyrotron using a dummy load. The current status will be discussed in this paper.

  12. 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)

    1999-01-01

    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.

  13. 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)

    2012-02-15

    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.

  14. 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)

    2006-10-24

    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.

  15. ASME code considerations for the compact heat exchanger

    SciTech Connect (OSTI)

    Nestell, James; Sham, Sam

    2015-08-31

    The mission of the U.S. Department of Energy (DOE), Office of Nuclear Energy is to advance nuclear power in order to meet the nation's energy, environmental, and energy security needs. Advanced high temperature reactor systems such as sodium fast reactors and high and very high temperature gas-cooled reactors are being considered for the next generation of nuclear reactor plant designs. The coolants for these high temperature reactor systems include liquid sodium and helium gas. Supercritical carbon dioxide (sCO?), a fluid at a temperature and pressure above the supercritical point of CO?, is currently being investigated by DOE as a working fluid for a nuclear or fossil-heated recompression closed Brayton cycle energy conversion system that operates at 550°C (1022°F) at 200 bar (2900 psi). Higher operating temperatures are envisioned in future developments. All of these design concepts require a highly effective heat exchanger that transfers heat from the nuclear or chemical reactor to the chemical process fluid or the to the power cycle. In the nuclear designs described above, heat is transferred from the primary to the secondary loop via an intermediate heat exchanger (IHX) and then from the intermediate loop to either a working process or a power cycle via a secondary heat exchanger (SHX). The IHX is a component in the primary coolant loop which will be classified as "safety related." The intermediate loop will likely be classified as "not safety related but important to safety." These safety classifications have a direct bearing on heat exchanger design approaches for the IHX and SHX. The very high temperatures being considered for the VHTR will require the use of very high temperature alloys for the IHX and SHX. Material cost considerations alone will dictate that the IHX and SHX be highly effective; that is, provide high heat transfer area in a small volume. This feature must be accompanied by low pressure drop and mechanical reliability and robustness. Classic shell and tube designs will be large and costly, and may only be appropriate in steam generator service in the SHX where boiling inside the tubes occurs. For other energy conversion systems, all of these features can be met in a compact heat exchanger design. This report will examine some of the ASME Code issues that will need to be addressed to allow use of a Code-qualified compact heat exchanger in IHX or SHX nuclear service. Most effort will focus on the IHX, since the safety-related (Class A) design rules are more extensive than those for important-to-safety (Class B) or commercial rules that are relevant to the SHX.

  16. 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

  17. Setting the stellar evolution clock for intermediate age populations

    E-Print Network [OSTI]

    R. Jimenez

    1999-06-04

    In this invited talk I show how the reddest and rarest galaxies at high redshift ($z \\simeq 1.5$) can be used to set the stellar evolution clock. I argue that one can confidently compute the collapse redshift of these objects. This yields to a high collapse redshift ($z>6$) and therefore their age is well constrained (in all cosmologies) between 3 and 4 Gyr. I also show that this is, indeed, the age derived using a variety of synthetic stellar population models when proper statistical tools are used to analyse their observed spectral energy distribution. This allows me to conclude that all stellar population models yield to the same consistent age for these galaxies, i.e. about 3.5 Gyr and that the stellar clock is properly set. Low ages are therefore excluded with high confidence.

  18. Kinematics of classical Cepheids in the Nuclear Stellar Disk

    E-Print Network [OSTI]

    Matsunaga, N; Yamamoto, R; Kobayashi, N; Inno, L; Genovali, K; Bono, G; Baba, J; Fujii, M S; Kondo, S; Ikeda, Y; Hamano, S; Nishiyama, S; Nagata, T; Aoki, W; Tsujimoto, T

    2014-01-01

    Classical Cepheids are useful tracers of the Galactic young stellar population because their distances and ages can be determined from their period-luminosity and period-age relations. In addition, the radial velocities and chemical abundance of the Cepheids can be derived from spectroscopic observations, providing further insights into the structure and evolution of the Galaxy. Here, we report the radial velocities of classical Cepheids near the Galactic Center, three of which were reported in 2011, the other reported for the first time. The velocities of these Cepheids suggest that the stars orbit within the Nuclear Stellar Disk, a group of stars and interstellar matter occupying a region of 200 pc around the Center, although the three-dimensional velocities cannot be determined until the proper motions are known. According to our simulation, these four Cepheids formed within the Nuclear Stellar Disk like younger stars and stellar clusters therein.

  19. Low-level radioactive-waste compacts. Status report as of July 1982

    SciTech Connect (OSTI)

    Not Available

    1982-07-01

    The Low-Level Radioactive Waste Policy Act (P.L. 96-573), enacted in December 1980, established as federal policy that states take responsibility for providing disposal capacity for low-level radioactive waste (LLW) generated within their borders, except for defense waste and Federal R and D. At the request of Senator James A. McClure, Chairman of the Senate Committee on Energy and Natural Resources, DOE has documented the progress of states individually and collectively in fulfilling their responsibilities under the Public Law. Regionalization through formation of low-level waste compacts has been the primary vehicle by which many states are assuming this responsibility. To date seven low-level waste compacts have been drafted and six have been enacted by state legislatures or ratified by a governor. As indicated by national progress to date, DOE considers the task of compacting achievable by the January 1, 1986, exclusionary date set in law, although several states and NRC questioned this.

  20. Scalable Automated Service Composition Using a Compact Directory Digest

    E-Print Network [OSTI]

    Binder, Walter

    Scalable Automated Service Composition Using a Compact Directory Digest Walter Binder, Ion: The directory offers a compact digest that service composition clients download to solve the hard part of a composition problem locally. In this paper we compare two different digest representations, a sparse matrix

  1. 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

  2. Compact gas meter assessment. Final report, May 1989-June 1990

    SciTech Connect (OSTI)

    Corliss, J.M.

    1994-06-01

    The overall objective of the Arthur D. Little meter evaluation program was to conduct a comprehensive, comparative evaluation of six compact gas meter concepts to assess their overall near- and long-term commercialization potential, and to recommend to GRI any further developments necessary to assure introduction of compact gas meters into the marketplace.

  3. Using Compact Data Representations for Languages Based on Catamorphisms

    E-Print Network [OSTI]

    Fegaras, Leonidas

    Using Compact Data Representations for Languages Based on Catamorphisms OGI, Tech­report #95 on using a compact vector representation for the recursive structure over which the catamorphism operates program performance, in particular by performing program fusion [13, 3, 7, 1]. In this paper, we explore

  4. The compact star in the SU(3) sigma model

    E-Print Network [OSTI]

    Ryszard Manka; Ilona Bednarek

    2004-11-04

    The linear chiral SU(3)*SU(3) model is applied to describe properties of the compact star matter inside the quark, protoneutron and neutron star.The leads to the neutron star with the value of maximum mass close to 1.5 solar mass and radius 11 km and with the reduced value of proton fraction and very compact hyperon core.

  5. Compact floating-gate true random number generator

    E-Print Network [OSTI]

    Maryland at College Park, University of

    Compact floating-gate true random number generator P. Xu, Y.L. Wong, T.K. Horiuchi and P.A. Abshire A compact true random number generator (RNG) integrated circuit with adjustable probability is presented. Introduction: Random number generation is indispensable in crypto- graphy, scientific computing and stochastic

  6. Low mass stellar evolution with WIMP capture and annihilation

    E-Print Network [OSTI]

    Pat Scott; Joakim Edsjö; Malcolm Fairbairn

    2007-11-07

    Recent work has indicated that WIMP annihilation in stellar cores has the potential to contribute significantly to a star's total energy production. We report on progress in simulating the effects of WIMP capture and annihilation upon stellar structure and evolution near supermassive black holes, using the new DarkStars code. Preliminary results indicate that low-mass stars are the most influenced by WIMP annihilation, which could have consequences for upcoming observational programs.

  7. Formation of a compact toroid for enhanced efficiency

    SciTech Connect (OSTI)

    Mozgovoy, A. G. [P.N. Lebedev Physical Institute, Moscow 119991 (Russian Federation)] [P.N. Lebedev Physical Institute, Moscow 119991 (Russian Federation); Romadanov, I. V.; Ryzhkov, S. V., E-mail: ryzhkov@power.bmstu.ru [Bauman Moscow State Technical University, Moscow 105005 (Russian Federation)

    2014-02-15

    We report here our results on the formation of a plasma configuration with the generic name of compact toroid (CT). A method of compact toroid formation to confine, heat and compress a plasma is investigated. Formation of a compact torus using an additional toroidal magnetic field helps to increase the plasma current to a maintainable level of the original magnetic field. We design the Compact Toroid Challenge (CTC) experiment in order to improve the magnetic flux trapping during field reversal in the formation of a compact toroid. The level of the magnetic field immersed in the plasma about 70% of the primary field is achieved. The CTC device and scheme of high level capturing of magnetic flux are presented.

  8. AGN Jet Mass Loading and Truncation by Stellar Winds

    E-Print Network [OSTI]

    Alexander Hubbard; Eric G. Blackman

    2006-04-28

    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.

  9. The Stellar Populations of NGC 3109: Another Dwarf Irregular Galaxy with a Population II Stellar Halo

    E-Print Network [OSTI]

    Dante Minniti; Albert Zijlstra; M. Victoria Alonso

    1998-10-29

    We have obtained V and I-band photometry for about 17500 stars in the field of the dwarf irregular galaxy NGC3109, located in the outskirts of the Local Group. The photometry allows us to study the stellar populations present inside and outside the disk of this galaxy. From the VI color-magnitude diagram we infer metallicities and ages for the stellar populations in the main body and in the halo of NGC3109. The stars in the disk of this galaxy have a wide variety of ages, including very young stars with approximately 10^7 yr. Our main result is to establish the presence of a halo consisting of population II stars, extending out to about 4.5 arcmin (or 1.8 kpc) above and below the plane of this galaxy. For these old stars we derive an age of > 10 Gyr and a metallicity of [Fe/H] = -1.8 +/- 0.2. We construct a deep luminosity function, obtaining an accurate distance modulus (m-M)_0 = 25.62 +/- 0.1 for this galaxy based on the I-magnitude of the red giant branch (RGB) tip and adopting E(V-I) = 0.05.

  10. 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)

    2014-04-20

    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.

  11. Extremely red stellar objects revealed by IPHAS

    E-Print Network [OSTI]

    N. J. Wright; R. Greimel; M. J. Barlow; J. E. Drew; M. -R. L. Cioni; A. A. Zijlstra; R. L. M. Corradi; E. A. González-Solares; P. Groot; J. Irwin; M. J. Irwin; A. Mampaso; R. A. H. Morris; D. Steeghs; Y. C. Unruh; N. Walton

    2008-11-04

    We present photometric analysis and follow-up spectroscopy for a population of extremely red stellar objects extracted from the point-source catalogue of the INT Photometric H-Alpha Survey (IPHAS) of the northern galactic plane. The vast majority of these objects have no previous identification. Analysis of optical, near- and mid-infrared photometry reveals that they are mostly highly-reddened asymptotic giant branch stars, with significant levels of circumstellar material. We show that the distribution of these objects traces galactic extinction, their highly reddened colours being a product of both interstellar and circumstellar reddening. This is the first time that such a large sample of evolved low-mass stars has been detected in the visual and allows optical counterparts to be associated with sources from recent infrared surveys. Follow-up spectroscopy on some of the most interesting objects in the sample has found significant numbers of S-type stars which can be clearly separated from oxygen-rich objects in the IPHAS colour-colour diagram. We show that this is due to the positions of different molecular bands relative to the narrow-band H-alpha filter used for IPHAS observations. The IPHAS (r' - H-alpha) colour offers a valuable diagnostic for identifying S-type stars. A selection method for identifying S-type stars in the galactic plane is briefly discussed and we estimate that over a thousand new objects of this type may be discovered, potentially doubling the number of known objects in this short but important evolutionary phase.

  12. Old stellar populations in distant radio galaxies

    E-Print Network [OSTI]

    James Dunlop

    1998-01-13

    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.

  13. Stellar populations in the Phoenix dwarf galaxy

    E-Print Network [OSTI]

    Enrico V. Held; Ivo Saviane; Yazan Momany

    1999-03-01

    We have obtained deep BVI CCD photometry of Phoenix, a galaxy considered a transition case between dwarf spheroidal and dwarf irregular galaxies. A comparison of our data with the RGBs of Galactic globular clusters gives a mean metal abundance [Fe/H] = -1.81+/-0.10 dex. The presence of an intrinsic color dispersion in the upper red RGB suggests an abundance range of about 0.5 dex, although a range in age may also affect the RGB width. For the first time, a HB has been revealed at V~23.8. The HB is predominantly red yet moderately extended to the blue, which indicates the presence of a significant population with age comparable to that of old halo GGCs. This HB morphology in a metal-poor system indicates a mild "second parameter" effect. From the mean level of the HB we derived a true distance modulus 23.21+/-0.08, in good agreement with the distance modulus 23.04+/-0.07 estimated from the cutoff of the RGB at I~23.1. We find a radial gradient in the HB morphology, and our CMDs show a small number of stars above the RGB tip, that most likely are AGB stars of an intermediate age population. Their number indicates that the fraction of intermediate age population in Phoenix is approximately 30-40%. A young stellar population is definitely present in Phoenix, consistent with a star formation episode started at least 0.6 Gyr ago, up to 1x10^{8} yr ago. Both young stars and AGB stars are centrally concentrated, which indicates that recent star formation preferentially occurred in the inner galaxy regions. In many respects, Phoenix appears not dissimilar from dwarf spheroidal galaxies in the Local Group.

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

    E-Print Network [OSTI]

    Thomas Cokelaer

    2007-06-29

    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).

  15. A Permanent-Magnet Microwave Ion Source for a Compact High-Yield Neutron Generator

    E-Print Network [OSTI]

    Waldmann, Ole

    2011-01-01

    a Compact High-Yield Neutron Generator O. Waldmann 1 , B.Compact High-Yield Neutron Generator ? O. Waldmann a and B.yield compact neutron generator for active interrogation

  16. Disease-associated polyglutamine stretches in monomeric huntingtin adopt a compact structure

    E-Print Network [OSTI]

    2012-01-01

    Adopts A Compact Structure data from fusion proteins withsimilar compact polyQ hairpin for all htt fusion proteins (compact conformation of mutant polyQ that we found for htt fusion

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

    E-Print Network [OSTI]

    Chantose, Prasongsit

    2012-02-14

    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...

  18. Manifold corrections on spinning compact binaries

    SciTech Connect (OSTI)

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

    2010-05-15

    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.

  19. Limits On The Spin Up Of Stellar-Mass Black Holes Through A Spiral Stationary Accretion Shock Instability

    E-Print Network [OSTI]

    Méndez, Enrique Moreno

    2015-01-01

    The spin of a number of black holes (BHs) in binary systems has been measured. In the case of BHs found in low-mass X-ray binaries (LMXBs) the observed values are in agreement with some theoretical predictions based on binary stellar evolution. However, using the same evolutionary models, the calculated spins of BHs in high-mass X-ray binaries (HMXBs) fall short compared to the observations. A possible solution to this conundrum is the accretion of high-specific-angular-momentum material after the formation of the BH, although this requires accretion above the Eddington limit. Another suggestion is that the observed high values of the BHs spin could be the result of an asymmetry during Core Collapse (CC). The only available energy to spin up the compact object during CC is its binding energy. A way to convert it to rotational kinetic energy is by using a Standing Accretion Shock Instability (SASI), which can develop during CC and push angular momentum into the central compact object through a spiral mode ($m ...

  20. Investigating accretion disk - radio jet coupling across the stellar mass scale

    E-Print Network [OSTI]

    Miller-Jones, James C A; Altamirano, Diego; Körding, Elmar G; Krimm, Hans A; Maitra, Dipankar; Remillard, Ron A; Russell, David M; Tudose, Valeriu; Dhawan, Vivek; Fender, Rob P; Heinz, Sebastian; Markoff, Sera; Migliari, Simone; Rupen, Michael P; Sarazin, Craig L

    2010-01-01

    Relationships between the X-ray and radio behavior of black hole X-ray binaries during outbursts have established a fundamental coupling between the accretion disks and radio jets in these systems. We begin by reviewing the prevailing paradigm for this disk-jet coupling, also highlighting what we know about similarities and differences with neutron star and white dwarf binaries. Until recently, this paradigm had not been directly tested with dedicated high-angular resolution radio imaging over entire outbursts. Moreover, such high-resolution monitoring campaigns had not previously targetted outbursts in which the compact object was either a neutron star or a white dwarf. To address this issue, we have embarked on the Jet Acceleration and Collimation Probe Of Transient X-Ray Binaries (JACPOT XRB) project, which aims to use high angular resolution observations to compare disk-jet coupling across the stellar mass scale, with the goal of probing the importance of the depth of the gravitational potential well, the...

  1. The role of stellar relaxation in the formation and evolution of the first massive black holes

    E-Print Network [OSTI]

    Yajima, Hidenobu

    2015-01-01

    We present calculations on the formation of massive black holes with 10^5 Msun at z > 6 that can be the seeds of supermassive black holes at z > 6. Under the assumption of compact star cluster formation in merging galaxies, star clusters in haloes of 10^8 ~ 10^9 Msun undergo rapid core-collapse leading to the formation of very massive stars (VMSs) with ~1000 Msun which directly collapse into black holes with similar masses. Star clusters in halos of > 10^9 Msun experience type-II supernovae before the formation of VMSs due to long core-collapse time scales. We also model the subsequent growth of black holes via accretion of residual stars in clusters. 2-body relaxation efficiently re-fills the loss cones of stellar orbits at larger radii and resonant relaxation at small radii is the main driver for accretion of stars onto black holes. As a result, more than ninety percent of stars in the initial cluster are swallowed by the central black holes before z=6. Using dark matter merger trees we derive black hole ma...

  2. Process for forming coal compacts and product thereof

    DOE Patents [OSTI]

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

    2002-01-01

    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.

  3. Accretion-Powered Stellar Winds III: Spin Equilibrium Solutions

    E-Print Network [OSTI]

    Sean Matt; Ralph E. Pudritz

    2008-02-12

    We compare the stellar wind torque calculated in a previous work (Paper II) to the spin-up and spin-down torques expected to arise from the magnetic interaction between a slowly rotating ($\\sim 10$% of breakup) pre-main-sequence star and its accretion disk. This analysis demonstrates that stellar winds can carry off orders of magnitude more angular momentum than can be transferred to the disk, provided that the mass outflow rates are greater than the solar wind. Thus, the equilibrium spin state is simply characterized by a balance between the angular momentum deposited by accretion and that extracted by a stellar wind. We derive a semi-analytic formula for predicting the equilibrium spin rate as a function only of the ratio of $\\dot M_{\\rm w} / \\dot M_{\\rm a}$ and a dimensionless magnetization parameter, $\\Psi \\equiv B_*^2 R_*^2 (\\dot M_{\\rm a} v_{\\rm esc})^{-1}$, where $\\dot M_{\\rm w}$ is the stellar wind mass outflow rate, $\\dot M_{\\rm a}$ the accretion rate, $B_*$ the stellar surface magnetic field strength, $R_*$ the stellar radius, and $v_{\\rm esc}$ the surface escape speed. For parameters typical of accreting pre-main-sequence stars, this explains spin rates of $\\sim 10$% of breakup speed for $\\dot M_{\\rm w} / \\dot M_{\\rm a} \\sim 0.1$. Finally, the assumption that the stellar wind is driven by a fraction of the accretion power leads to an upper limit to the mass flow ratio of $\\dot M_{\\rm w} / \\dot M_{\\rm a} \\la 0.6$.

  4. Considerations for evaluating proposed low-level radioactive waste compacts

    SciTech Connect (OSTI)

    Not Available

    1985-02-01

    Thirty-nine States have enacted legislation related to this Act, and five compacts have been submitted to Congress for consent. Other compacts are being negotiated, one in the West and several in the Midwest and Northeast. The Department of Energy has identified a number of items, which if included in the congressional review of each compact, would be likely to increase the possibility that new disposal sites will be developed and properly supported. The Department is providing additional perspectives that have not been previously included in testimony or reports. By suggesting examination of several general elements of a compact proposal, the Department hopes to provide a common focus that may be useful to the Congress in integrating all available information. The Department believes that the Congress should consider the following key items when reviewing the compacts: Commitments that assure the provision of new disposal capacity in the form of a host-State and site selection process with schedules and a target date for new sites to be opened; Commitments that provide short-term measures for storage, treatment, or disposal during an interim period when such new capacity may not be available; Consistency of definitions with 10 CFR Part 61 to assure the compact plan presents a total solution for all low-level waste generated within the region; Periodic review of the compacts by the Congress to examine concerns that are more easily assessed after a compact becomes operational, e.g., economic viability and long-term institutional control; and Economic viability of a compact, when reviewed in the future, in terms of the benefits and the costs specific to that region.

  5. Polymer quantum effects on compact stars models

    E-Print Network [OSTI]

    Guillermo Chacon-Acosta; Hector Hernandez-Hernandez

    2014-08-05

    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 $\\lambda^2\\lesssim 10^{-26}m^2$.

  6. The spheromak as a compact fusion reactor

    SciTech Connect (OSTI)

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

    1987-03-01

    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.

  7. Color superconducting quark matter in compact stars

    E-Print Network [OSTI]

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

    2007-12-02

    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.

  8. 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)

  9. Neutron stars: compact objects with relativistic gravity

    E-Print Network [OSTI]

    Ek?i, K Yavuz

    2015-01-01

    General properties of neutron stars are briefly reviewed with an emphasis on the indispensability of general relativity in our understanding of these fascinating objects. In Newtonian gravity the pressure within a star merely plays the role of opposing self-gravity. In general relativity all sources of energy and momentum contribute to the gravity. As a result the pressure not only opposes gravity but also enhances it. The later role of pressure becomes more pronounced with increasing compactness, $M/R$ where $M$ and $R$ are the mass and radius of the star, and sets a critical mass beyond which collapse is inevitable. This critical mass has no Newtonian analogue; it is conceptually different than the Stoner-Landau-Chandrasekhar limit in Newtonian gravity which is attained asymptotically for ultra-relativistic fermions. For white dwarfs the general relativistic critical mass is very close to the Stoner-Landau-Chandrasekhar limit. For neutron stars the maximum mass---so called Oppenheimer-Volkoff limit---is sig...

  10. 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

    2008-12-01

    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.

  11. Consent Order, Lawrence Livermore National National Security...

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

    Lawrence Livermore National National Security, LLC - WCO-2010-01 Consent Order, Lawrence Livermore National National Security, LLC - WCO-2010-01 October 29, 2010 Issued to Lawrence...

  12. Accretion-powered Stellar Winds as a Solution to the Stellar Angular Momentum Problem

    E-Print Network [OSTI]

    Sean Matt; Ralph E. Pudritz

    2005-10-03

    We compare the angular momentum extracted by a wind from a pre-main-sequence star to the torques arising from the interaction between the star and its Keplerian accretion disk. We find that the wind alone can counteract the spin-up torque from mass accretion, solving the mystery of why accreting pre-main-sequence stars are observed to spin at less than 10% of break-up speed, provided that the mass outflow rate in the stellar winds is ~10% of the accretion rate. We suggest that such massive winds will be driven by some fraction $\\epsilon$ of the accretion power. For observationally constrained typical parameters of classical T-Tauri stars, $\\epsilon$ needs to be between a few and a few tens of percent. In this scenario, efficient braking of the star will terminate simultaneously with accretion, as is usually assumed to explain the rotation velocities of stars in young clusters.

  13. 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)

    2012-11-01

    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.

  14. Stellar Populations and Surface Brightness Fluctuations: New Observations and Models

    E-Print Network [OSTI]

    John P. Blakeslee; Alexandre Vazdekis; Edward A. Ajhar

    2000-08-15

    We examine the use of surface brightness fluctuations (SBF) for both stellar population and distance studies. New V-band SBF data are reported for five Fornax cluster galaxies and combined with literature data to define a new V-band SBF distance indicator. We use new stellar population models, based on the latest Padua isochrones transformed empirically to the observational plane, to predict SBF magnitudes and integrated colours for a wide range of population ages and metallicities. We examine the sensitivity of the predictions to changes in the isochrones, transformations, and IMF. The new models reproduce the SBF data for globular clusters fairly well, especially if higher metallicity globulars are younger. The models also give a good match to the "fluctuation colors" of elliptical galaxies. In order to obtain theoretical calibrations of the SBF distance indicators, we combine our single-burst models into composite population models. These models reproduce the observed behavior of the SBF magnitudes as a function of stellar population parameters, including the steep colour dependence found for HST/WFPC2 F814W SBF data. Because the theoretical SBF calibrations are fairly sensitive to uncertain details of stellar evolution, the empirical calibrations are more secure. However, the sensitivity of SBF to these finer details potentially makes it a powerful constraint for stellar evolution and population synthesis. [abbridged

  15. The Magellanic Bridge: The Nearest Purely Tidal Stellar Population

    E-Print Network [OSTI]

    Jason Harris

    2006-12-04

    We report on observations of the stellar populations in twelve fields spanning the region between the Magellanic Clouds, made with the Mosaic-II camera on the 4-meter telescope at the Cerro-Tololo Inter-American Observatory. The two main goals of the observations are to characterize the young stellar population (which presumably formed in situ in the Bridge and therefore represents the nearest stellar population formed from tidal debris), and to search for an older stellar component (which would have been stripped from either Cloud as stars, by the same tidal forces which formed the gaseous Bridge). We determine the star-formation history of the young inter-Cloud population, which provides a constraint on the timing of the gravitational interaction which formed the Bridge. We do not detect an older stellar population belonging to the Bridge in any of our fields, implying that the material that was stripped from the Clouds to form the Magellanic Bridge was very nearly a pure gas.

  16. Averaged equilibrium and stability in low-aspect-ratio stellarators

    SciTech Connect (OSTI)

    Garcia, L.; Carreras, B.A.; Dominguez, N.

    1989-01-01

    The MHD equilibrium and stability calculations or stellarators are complex because of the intrinsic three-dimensional (3-D) character of these configurations. The stellarators expansion simplifies the equilibrium calculation by reducing it to a two-dimensional (2-D) problem. The classical stellarator expansion includes terms up to order epsilon/sup 2/, and the vacuum magnetic field is also included up to this order. For large-aspect-ratio configurations, the results of the stellarator expansion agree well with 3-D numerical equilibrium results. But for low-aspect-ratio configurations, these are significant discrepancies with 3-D equilibrium calculations. The main reason for these discrepancies is the approximation in the vacuum field contributions. This problem can be avoided by applying the average method in a vacuum flux coordinate system. In this way, the exact vacuum magnetic field contribution is included and the results agree well with 3-D equilibrium calculations even for low-aspect-ratio configurations. Using the average method in a vacuum flux coordinate system also permit the accurate calculation of local stability properties with the Mercier criterion. The main improvement is in the accurate calculation of the geodesic curvature term. In this paper, we discuss the application of the average method in flux coordinates to the calculation of the Mercier criterion for low-aspect-ratio stellarator configurations. 12 refs., 3 figs.

  17. Stellar signatures of AGN-jet-triggered star formation

    SciTech Connect (OSTI)

    Dugan, Zachary; Silk, Joseph; Bryan, Sarah; Gaibler, Volker; Haas, Marcel

    2014-12-01

    To investigate feedback between relativistic jets emanating from active galactic nuclei and the stellar population of the host galaxy, we analyze the long-term evolution of the orbits of the stars formed in the galaxy-scale simulations by Gaibler et al. of jets in massive, gas-rich galaxies at z ? 2-3. We find strong, jet-induced differences in the resulting stellar populations of galaxies that host relativistic jets and galaxies that do not, including correlations in stellar locations, velocities, and ages. Jets are found to generate distributions of increased radial and vertical velocities that persist long enough to effectively augment the stellar structure of the host. The jets cause the formation of bow shocks that move out through the disk, generating rings of star formation within the disk. The bow shock often accelerates pockets of gas in which stars form, yielding populations of stars with significant radial and vertical velocities, some of which have large enough velocities to escape the galaxy. These stellar population signatures can serve to identify past jet activity as well as jet-induced star formation.

  18. Is scalar-tensor gravity consistent with polytropic stellar models?

    E-Print Network [OSTI]

    Kaisa Henttunen; Iiro Vilja

    2015-03-01

    We study the scalar field potential $V(\\phi)$ in the scalar-tensor gravity with self-consistent polytropic stellar configurations. Without choosing a particular potential, we numerically derive the potential inside various stellar objects. We restrict the potential to conform to general relativity or to $f(R)$ gravity inside and require the solution to arrive at SdS vacuum at the surface. The studied objects are required to obtain observationally valid masses and radii corresponding to solar type stars, white dwarfs and neutron stars. We find that the resulting scalar-tensor potential $V(\\phi)$ for the numerically derived polytrope that conforms to general relativity, in each object class, is highly dependent on the matter configuration as well as on the vacuum requirement at the boundary. As a result, every stellar configuration arrives at a potential $V(\\phi)$ that is not consistent with the other stellar class potentials. Therefore, a general potential that conforms to all these polytropic stellar classes could not be found.

  19. The Most Massive Ultra-Compact Dwarf Galaxy in the Virgo Cluster

    E-Print Network [OSTI]

    Liu, Chengze; Toloba, Elisa; Mihos, J Christopher; Ferrarese, Laura; Alamo-Martínez, Karla; Zhang, Hong-Xin; Côté, Patrick; Cuillandre, Jean-Charles; Cunningham, Emily C; Guhathakurta, Puragra; Gwyn, Stephen; Herczeg, Gregory; Lim, Sungsoon; Puzia, Thomas H; Roediger, Joel; Sánchez-Janssen, Rubén; Yin, Jun

    2015-01-01

    We report on the properties of the most massive ultra-compact dwarf galaxy (UCD) in the nearby Virgo Cluster of galaxies using imaging from the Next Generation Virgo Cluster Survey (NGVS) and spectroscopy from Keck/DEIMOS. This object (M59-UCD3) appears to be associated with the massive Virgo galaxy M59 (NGC 4621), has an integrated velocity dispersion of 78 km/s, a dynamical mass of $3.7\\times10^8 M_\\odot$, and an effective radius ($R_e$) of 25 pc. With an effective surface mass density of $9.4\\times10^{10} M_\\odot/kpc^2$, it is the densest galaxy in the local Universe discovered to date, surpassing the density of the luminous Virgo UCD, M60-UCD1. M59-UCD3 has a total luminosity of $M_{g'}=-14.2$ mag, and a spectral energy distribution consistent with an old (14 Gyr) stellar population with [Fe/H]=0.0 and [$\\alpha$/Fe]=+0.2. We also examine deep imaging around M59 and find a broad low surface brightness stream pointing towards M59-UCD3, which may represent a tidal remnant of the UCD progenitor. This UCD, alo...

  20. An improved pipeline to search for gravitational waves from compact binary coalescence

    E-Print Network [OSTI]

    Usman, Samantha A; Nitz, Alexander H; Harry, Ian W; Brown, Duncan A; Capano, Collin D; Dent, Thomas; Fairhurst, Stephen; Pfeiffer, Harald P; Biwer, Christopher M; Canton, Tito Dal; Keppel, Drew; Saulson, Peter R; West, Matthew; Willis, Joshua L

    2015-01-01

    The second generation of ground-based gravitational-wave detectors will begin taking data in September 2015. Sensitive and computationally-efficient data analysis methods will be required to maximize what we learn from their observations. We describe improvements made to the offline analysis pipeline searching for gravitational waves from stellar-mass compact binary coalescences, and assess how these improvements affect search sensitivity. Starting with the two-stage ihope pipeline used in S5, S6 and VSR1-3 and using two weeks of S6/VSR3 data as test periods, we first demonstrate a pipeline with a simpler workflow. This single-stage pipeline performs matched filtering and coincidence testing only once. This simplification allows us to reach much lower false-alarm rates for loud candidate events. We then describe an optimized chi-squared test which minimizes computational cost. Next, we compare methods of generating template banks, demonstrating that a fixed bank may be used for extended stretches of time. Fix...

  1. An improved pipeline to search for gravitational waves from compact binary coalescence

    E-Print Network [OSTI]

    Samantha A. Usman; Marcel S. Kehl; Alexander H. Nitz; Ian W. Harry; Duncan A. Brown; Collin D. Capano; Thomas Dent; Stephen Fairhurst; Harald P. Pfeiffer; Christopher M. Biwer; Tito Dal Canton; Drew Keppel; Peter R. Saulson; Matthew West; Joshua L. Willis

    2015-08-10

    The second generation of ground-based gravitational-wave detectors will begin taking data in September 2015. Sensitive and computationally-efficient data analysis methods will be required to maximize what we learn from their observations. We describe improvements made to the offline analysis pipeline searching for gravitational waves from stellar-mass compact binary coalescences, and assess how these improvements affect search sensitivity. Starting with the two-stage ihope pipeline used in S5, S6 and VSR1-3 and using two weeks of S6/VSR3 data as test periods, we first demonstrate a pipeline with a simpler workflow. This single-stage pipeline performs matched filtering and coincidence testing only once. This simplification allows us to reach much lower false-alarm rates for loud candidate events. We then describe an optimized chi-squared test which minimizes computational cost. Next, we compare methods of generating template banks, demonstrating that a fixed bank may be used for extended stretches of time. Fixing the bank reduces the cost and complexity, compared to the previous method of regenerating a template bank every 2048 s of analyzed data. Creating a fixed bank shared by all detectors also allows us to apply a more stringent coincidence test, whose performance we quantify. With these improvements, we find a 10% increase in sensitive volume with a negligible change in computational cost.

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

    E-Print Network [OSTI]

    Bence Kocsis; Janna Levin

    2012-07-09

    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.

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

    E-Print Network [OSTI]

    Eigenthaler, Paul; Verdugo, Miguel; Ziegler, Bodo

    2015-01-01

    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...

  4. Nonlinear oscillations of compact stars in the vicinity of the maximum mass configuration

    E-Print Network [OSTI]

    Alessandro Brillante; Igor Mishustin

    2015-07-17

    We solve the dynamical GR equations for the spherically symmetric evolution of compact stars in the vicinity of the maximum mass, for which instability sets in according to linear perturbation theory. The calculations are done with the analytical Zeldovich-like EOS P=a(rho-rho_0) and with the TM1 parametrisation of the RMF model. The initial configurations for the dynamical calculations are represented by spherical stars with equilibrium density profile, which are perturbed by either (i) an artificially added inward velocity field proportional to the radial coordinate, or (ii) a rarefaction corresponding to a static and expanded star. These configurations are evolved using a one-dimensional GR hydro code for ideal and barotropic fluids. Depending on the initial conditions we obtain either stable oscillations or the collapse to a black hole. The minimal amplitude of the perturbation, needed to trigger gravitational collapse is evaluated. The approximate independence of this energy on the type of perturbation is pointed out. At the threshold we find type I critical behaviour for all stellar models considered and discuss the dependence of the time scaling exponent on the baryon mass and EOS.

  5. Analysis of powder compaction process through equal channel angular extrusion 

    E-Print Network [OSTI]

    Kaushik, Anshul

    2009-05-15

    A thermodynamic framework was presented for the development of powderconstitutive models. The process of powder compaction through Equal ChannelAngular Extrusion (ECAE) at room temperature was modeled using the finiteelement ...

  6. 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

  7. Geometric sufficient conditions for compactness of the ?-Neumann operator 

    E-Print Network [OSTI]

    Munasinghe, Samangi

    2009-06-02

    For smooth bounded pseudoconvex domains in Cn, we provide geometric conditions on (the points of infinite type in) the boundary which imply compactness of the ?-Neumann operator. This is an extension of a theorem of Straube ...

  8. Identity Crises and Strong Compactness II: Strong Cardinals

    E-Print Network [OSTI]

    Cummings, James

    that no strongly compact cardinal #20; is 2 #20; = #20; + supercompact. #3; Supported by the Volkswagen 667379. y Supported by the Volkswagen-Stiftung (RiP-program at Oberwolfach). In addition, this research

  9. 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...

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

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

    -- Washington D.C. ape012taylor2010o.pdf More Documents & Publications Development, Test and Demonstration of a Cost-Effective, Compact, Light-Weight, and Scalable High...

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

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

    2009 -- Washington D.C. ape07taylor.pdf More Documents & Publications Development, Test and Demonstration of a Cost-Effective, Compact, Light-Weight, and Scalable High...

  12. A compact neutron generator using a field ionization source

    E-Print Network [OSTI]

    Persaud, Arun

    2012-01-01

    Handbook of Fast Neutron Generators Volume I (CRC Press,A compact neutron generator using a ?eld ionization sourcewell logging with neutron generators. 2 Due to the harsh en-

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

    SciTech Connect (OSTI)

    R. Raman

    2008-11-04

    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.

  14. The Compact RCS / Antenna Range at MIT Lincoln Laboratory

    E-Print Network [OSTI]

    Shields, Michael W.

    A new compact range with a state-of-the-art instrumentation system was installed at Lincoln Laboratory and is currently in use. This paper describes the chamber with varied-height absorber, the rolled-edge reflector and ...

  15. Inhomogeneous color superconductivity and the cooling of compact stars

    E-Print Network [OSTI]

    M. Ruggieri

    2007-04-13

    In this talk I discuss the inhomogeneous (LOFF) color superconductive phases of Quantum Chromodynamics (QCD). In particular, I show the effect of a core of LOFF phase on the cooling of a compact star.

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

    E-Print Network [OSTI]

    Lazaridis, A.; Rafailidis, E.

    1995-01-01

    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...

  17. Development of Compact Gaseous Sensors with Internal Reference...

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

    NOx in Combustion Environments Compact sensors have been developed to allow for real-time monitoring of O2 and NOx during combustion. deer08singh.pdf More Documents & Publications...

  18. National Laboratory

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

    on the Pajarito Plateau topic of inaugural lecture at Los Alamos National Laboratory January 4, 2013 Lecture series begins yearlong commemoration of 70th anniversary LOS...

  19. 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

    2015-01-01

    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.

  20. A HIGH STELLAR OBLIQUITY IN THE WASP-7 EXOPLANETARY SYSTEM

    SciTech Connect (OSTI)

    Albrecht, Simon; Winn, Joshua N.; Hirano, Teruyuki; Butler, R. Paul; Crane, Jeffrey D.; Shectman, Stephen A.; Thompson, Ian B.; Wittenmyer, Robert A.

    2012-01-10

    We measure a tilt of 86 Degree-Sign {+-} 6 Degree-Sign between the sky projections of the rotation axis of the WASP-7 star and the orbital axis of its close-in giant planet. This measurement is based on observations of the Rossiter-McLaughlin (RM) effect with the Planet Finder Spectrograph on the Magellan II telescope. The result conforms with the previously noted pattern among hot-Jupiter hosts, namely, that the hosts lacking thick convective envelopes have high obliquities. Because the planet's trajectory crosses a wide range of stellar latitudes, observations of the RM effect can in principle reveal the stellar differential rotation profile; however, with the present data the signal of differential rotation could not be detected. The host star is found to exhibit radial-velocity noise ({sup s}tellar jitter{sup )} with an amplitude of Almost-Equal-To 30 m s{sup -1} over a timescale of days.

  1. Period change and stellar evolution of $\\beta$ Cephei stars

    E-Print Network [OSTI]

    Neilson, Hilding R

    2015-01-01

    The $\\beta$ Cephei stars represent an important class of massive star pulsators probing the evolution of B-type stars and the transition from main sequence to hydrogen-shell burning evolution. By understanding $\\beta$ Cep stars, we gain insights into the detailed physics of massive star evolution such as rotational mixing, convective core overshooting, magnetic fields and stellar winds, all of which play important roles. Similarly, modeling their pulsation provides additional information into their interior structures. Furthermore, measurements of the rate of change of pulsation period offer a direct measure of $\\beta$ Cephei stellar evolution. In this work, we compute state-of-the-art stellar evolution models assuming different amounts of initial rotation and convective core overshoot and measure theoretical rates of period change for which we compare to rates previously measured for a sample of $\\beta$ Cephei stars. The results of this comparison are mixed. For three stars, the rates are too small to infer ...

  2. Observational techniques to measure solar and stellar oscillations

    E-Print Network [OSTI]

    Garcia, Rafael A

    2015-01-01

    As said by Sir A. Eddington in 1925: Our telescopes may probe farther and farther into the depths of space. At first sight it would seem that the deep interior of the sun and stars is less accessible to scientific investigation than any other region of the universe. What appliance can pierce through the outer layers of a star and test the conditions within? Eddington (1926). Nowadays, asteroseismology has proven its ability to pierce below stellar pho- tospheres and allow us to see inside the interior of thousands of stars down to the stellar cores, answering the question asked by Eddington ninety years ago. In this chapter we review the general properties of the spectral analysis which is the base of any asteroseismic investigation. After describing the stellar power spectrum, we will describe in details the characterization of the modal spec- trum. This chapter will end by a brief description of the instrumentation in both helio and asteroseismology.

  3. BASTI: An interactive database of updated stellar evolution models

    E-Print Network [OSTI]

    S. Cassisi; A. Pietrinferni; M. Salaris; F. Castelli; D. Cordier; M. Castellani

    2005-09-19

    We present a new database of stellar evolution models for a large range of masses and chemical compositions, based on an up-to-date theoretical framework. We briefly discuss the physical inputs and the assumptions adopted in computing the stellar models. We explain how to access to the on-line archive and briefly discuss the interactive WEB tools that can be used to compute user-specified evolutionary tracks/isochrones/luminosity functions. The future developments of this database are also outlined.

  4. Fractal properties of stellar systems and random forces

    E-Print Network [OSTI]

    Chumak, Oleg V

    2015-01-01

    The nearest neighbor distribution (Chandrasekhar 1943) is generalized to fractal stellar systems.For such systems an asymptotic distribution of the magnitude of large random forces and a formula for the effective mean interparticle spacing are derived. It is shown that in the case of a power-law distribution of conditional density the derived asymptotic fully agrees with the results obtained in terms of a general approach. It is concluded that large random forces in a fractal stellar medium are due entirely to the nearest neighbors (clumps) located inside the sphere of the effective radius determined from the generalized Holtsmark distribution.

  5. Computing Limb Darkening Coefficients from Stellar Atmosphere Models

    E-Print Network [OSTI]

    David Heyrovsky

    2006-10-24

    We explore the sensitivity of limb darkening coefficients computed from stellar atmosphere models to different least-squares fitting methods. We demonstrate that conventional methods are strongly biased to fitting the stellar limb. Our suggested method of fitting by minimizing the radially integrated squared residual yields improved fits with better flux conservation. The differences of the obtained coefficients from commonly used values are observationally significant. We show that the new values are in better agreement with solar limb darkening measurements as well as with coefficients reported from analyses of eclipsing binary light curves.

  6. Nuclear reactions in hot stellar matter and nuclear surface deformation

    E-Print Network [OSTI]

    V. Yu. Denisov

    2006-11-13

    Cross-sections for capture reactions of charged particles in hot stellar matter turn out be increased by the quadrupole surface oscillations, if the corresponding phonon energies are of the order of the star temperature. The increase is studied in a model that combines barrier distribution induced by surface oscillations and tunneling. The capture of charged particles by nuclei with well-deformed ground-state is enhanced in stellar matter. It is found that the influence of quadrupole surface deformation on the nuclear reactions in stars grows, when mass and proton numbers in colliding nuclei increase.

  7. PARTIAL COMPACT QUANTUM GROUPS KENNY DE COMMER1 AND THOMAS TIMMERMANN2

    E-Print Network [OSTI]

    Timmermann, Thomas

    that partial compact quantum groups are in one-to-one correspondence with concrete partial fusion CPARTIAL COMPACT QUANTUM GROUPS KENNY DE COMMER1 AND THOMAS TIMMERMANN2 Abstract. Compact quantum groups of face type, as introduced by Hayashi, form a class of compact quantum groupoids with a classical

  8. Solar Physics A Journal for Solar and Solar-Stellar

    E-Print Network [OSTI]

    Padmanabhan, Janardhan

    investigated in the build-up to one of the deepest solar minima expe- rienced in the past 100 years1 23 Solar Physics A Journal for Solar and Solar-Stellar Research and the Study of Solar-013-0335-3 Changes in Quasi-periodic Variations of Solar Photospheric Fields: Precursor to the Deep Solar Minimum

  9. 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

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

    E-Print Network [OSTI]

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

    2008-02-22

    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.

  11. X-rays from Hot Stars: Stellar Astronomy Research with

    E-Print Network [OSTI]

    Cohen, David

    emission lines Hot stars*: massive outflows ("stellar winds") ­ are the x-rays associated with these winds can actually take an image of its "wind nebula" ­ in all other cases, we infer the presence of a wind a model for fitting the detailed shapes of x-ray emission line profiles from hot star winds The very hot

  12. Hamilton-Jacobi Modelling of Stellar Pini Gurfil

    E-Print Network [OSTI]

    Hamilton-Jacobi Modelling of Stellar Dynamics Pini Gurfil Faculty of Aerospace Engineering and a high-order term. The Hamilton- Jacobi equations are solved for the linear part by separation, and new, and then perform a Legendre transformation to find the Hamiltonian. We solve the Hamilton-Jacobi equations

  13. PHASE-REFERENCED STELLAR INTERFEROMETRY AT THE PALOMAR TESTBED INTERFEROMETER

    E-Print Network [OSTI]

    PHASE-REFERENCED STELLAR INTERFEROMETRY AT THE PALOMAR TESTBED INTERFEROMETER Benjamin F. Lane implementation and testing of phase referencing at the Palomar Testbed Interferometer. A new instrument) to allow an accurate measurement of the fringe phase and, thus, to allow fringe tracking. At the Palomar

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

    SciTech Connect (OSTI)

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

    2012-04-20

    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.

  15. Henry Kandrup's Ideas About Relaxation of Stellar Systems

    E-Print Network [OSTI]

    David Merritt

    2005-02-14

    Henry Kandrup wrote prolifically on the problem of relaxation of stellar systems. His picture of relaxation was significantly more refined than the standard description in terms of phase mixing and violent relaxation. In this article, I summarize Henry's work in this and related areas.

  16. Statistical Methods for Detecting Stellar Occultations by Kuiper Belt Objects

    E-Print Network [OSTI]

    Rice, John

    Statistical Methods for Detecting Stellar Occultations by Kuiper Belt Objects: the Taiwanese in the Kuiper Belt, by measuring the rate of occultations of stars by these objects, using an array of three of the solar system. This belt is the source of most short­period comets, those with periods of 200 years

  17. CAN STELLAR MIXING EXPLAIN THE LACK OF TYPE Ib SUPERNOVAE IN...

    Office of Scientific and Technical Information (OSTI)

    CAN STELLAR MIXING EXPLAIN THE LACK OF TYPE Ib SUPERNOVAE IN LONG-DURATION GAMMA-RAY BURSTS? Citation Details In-Document Search Title: CAN STELLAR MIXING EXPLAIN THE LACK OF TYPE...

  18. 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

  19. NATIONAL LABORATORY

    Office of Environmental Management (EM)

    a modified United Nations Test for Oxidizing Solids protocol. * 2010 burn-rate tests at New Mexico Tech performed on two types of surrogates of the buried Rocky Flats salt...

  20. 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 ...

  1. 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.

    1984-08-01

    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.

  2. On second cohomology of duals of compact groups

    E-Print Network [OSTI]

    Neshveyev, Sergey

    2010-01-01

    We show that for any compact connected group G the second cohomology group defined by unitary invariant 2-cocycles on \\hat G is canonically isomorphic to H^2(\\widehat{Z(G)};T). This implies that the group of autoequivalences of the C*-tensor category Rep G is isomorphic to H^2(\\widehat{Z(G)};T)\\rtimes\\Out(G). We also show that a compact connected group G is completely determined by Rep G. More generally, extending a result of Etingof-Gelaki and Izumi-Kosaki we describe all pairs of compact separable monoidally equivalent groups. The proofs rely on the theory of ergodic actions of compact groups developed by Landstad and Wassermann and on its algebraic counterpart developed by Etingof and Gelaki for the classification of triangular semisimple Hopf algebras. In two appendices we give a self-contained account of amenability of tensor categories, fusion rings and discrete quantum groups, and prove an analogue of Radford's theorem on minimal Hopf subalgebras of quasitriangular Hopf algebras for compact quantum gro...

  3. New Database of Geneva Stellar Evolution Models with Empirically Calibrated Spectral Libraries: Bridging

    E-Print Network [OSTI]

    Schaerer, Daniel

    New Database of Geneva Stellar Evolution Models with Empirically Calibrated Spectral Libraries introduce a new database which ``translates'' the complete set of Geneva stellar evolution models to various, Switzerland Abstract. We have constructed an extended database of stellar evolu­ tion tracks and isochrones

  4. Splinter Proposal for Cool Stars 16 Title: Solar and Stellar Flares

    E-Print Network [OSTI]

    Hudson, Hugh

    Splinter Proposal for Cool Stars 16 Title: Solar and Stellar Flares 1. Names of the session for CS16. Solar and stellar flares have striking similarities, so important parts of the underlying to initiate discussions to bridge this gap, via a splinter session on solar and stellar flares at Cool Stars

  5. 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

  6. High lumen compact fluorescents boost light output in new fixtures

    SciTech Connect (OSTI)

    1992-12-31

    Some compact fluorescent lamps aren`t so compact. General Electric (GE), OSRAM, and Philips have been expanding offerings in longer, more powerful, hard wired CFLs that generate enough light to serve applications once limited to conventional fluorescents and metal halide systems. All three of these manufacturers have for some time offered 18- to 40-watt high-output CFLs, which use a fluorescent tube doubled back on itself to produce a lot of light in a compact source. Now GE has introduced an even larger, more powerful 50-watt unit, and OSRAM is soon to follow suit with a 55-watt lamp. These new entries to the field of turbocharged CFLs can provide general lighting at ceiling heights of 12 feet or more as well as indirect lighting, floodlighting, and wall washing. They are such a concentrated source of light that they can provide the desired illumination using fewer lamps and fixtures than would be needed with competing sources.

  7. SEARCH FOR IONIZED JETS TOWARD HIGH-MASS YOUNG STELLAR OBJECTS

    SciTech Connect (OSTI)

    Guzman, Andres E.; Garay, Guido; Brooks, Kate J.; Voronkov, Maxim A.

    2012-07-01

    We are carrying out multi-frequency radio continuum observations, using the Australia Telescope Compact Array, to systematically search for collimated ionized jets toward high-mass young stellar objects (HMYSOs). Here we report observations at 1.4, 2.4, 4.8, and 8.6 GHz, made with angular resolutions of about 7'', 4'', 2'', and 1'', respectively, toward six objects of a sample of 33 southern HMYSOs thought to be in very early stages of evolution. The objects in the sample were selected from radio and infrared catalogs by having positive radio spectral indices and being luminous (L{sub bol} > 2 Multiplication-Sign 10{sup 4} L{sub Sun }), but underluminous in radio emission compared with that expected from its bolometric luminosity. This criterion makes the radio sources good candidates for being ionized jets. As part of this systematic search, two ionized jets have been discovered: one previously published and the other reported here. The rest of the observed candidates correspond to three hypercompact H II regions and two ultracompact H II regions. The two jets discovered are associated with two of the most luminous (7 Multiplication-Sign 10{sup 4} and 1.0 Multiplication-Sign 10{sup 5} L{sub Sun }) HMYSOs known to harbor this type of object, showing that the phenomena of collimated ionized winds appear in the formation process of stars at least up to masses of {approx}20 M{sub Sun} and provide strong evidence for a disk-mediated accretion scenario for the formation of high-mass stars. From the incidence of jets in our sample, we estimate that the jet phase in high-mass protostars lasts for {approx}4 Multiplication-Sign 10{sup 4} yr.

  8. Advances in compact proton spectrometers for inertial-confinement fusion and plasma nuclear science

    SciTech Connect (OSTI)

    Seguin, F. H.; Sinenian, N.; Rosenberg, M.; Zylstra, A.; Manuel, M. J.-E.; Sio, H.; Waugh, C.; Rinderknecht, H. G.; Johnson, M. Gatu; Frenje, J.; Li, C. K.; Petrasso, R. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Sangster, T. C.; Roberts, S. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

    2012-10-15

    Compact wedge-range-filter proton spectrometers cover proton energies {approx}3-20 MeV. They have been used at the OMEGA laser facility for more than a decade for measuring spectra of primary D{sup 3}He protons in D{sup 3}He implosions, secondary D{sup 3}He protons in DD implosions, and ablator protons in DT implosions; they are now being used also at the National Ignition Facility. The spectra are used to determine proton yields, shell areal density at shock-bang time and compression-bang time, fuel areal density, and implosion symmetry. There have been changes in fabrication and in analysis algorithms, resulting in a wider energy range, better accuracy and precision, and better robustness for survivability with indirect-drive inertial-confinement-fusion experiments.

  9. Compact 'diode-based' multi-energy soft x-ray diagnostic for NSTX

    SciTech Connect (OSTI)

    Tritz, K.; Clayton, D. J.; Stutman, D.; Finkenthal, M. [Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2012-10-15

    A novel and compact, diode-based, multi-energy soft x-ray (ME-SXR) diagnostic has been developed for the National Spherical Tokamak Experiment. The new edge ME-SXR system tested on NSTX consists of a set of vertically stacked diode arrays, each viewing the plasma tangentially through independent pinholes and filters providing an overlapping view of the plasma midplane which allows simultaneous SXR measurements with coarse sub-sampling of the x-ray spectrum. Using computed x-ray spectral emission data, combinations of filters can provide fast (>10 kHz) measurements of changes in the electron temperature and density profiles providing a method to 'fill-in' the gaps of the multi-point Thomson scattering system.

  10. SimTrack: A compact c++ code for particle orbit and spin tracking in accelerators

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

    Luo, Yun

    2015-08-29

    SimTrack is a compact c++ code of 6-d symplectic element-by-element particle tracking in accelerators originally designed for head-on beam–beam compensation simulation studies in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. It provides a 6-d symplectic orbit tracking with the 4th order symplectic integration for magnet elements and the 6-d symplectic synchro-beam map for beam–beam interaction. Since its inception in 2009, SimTrack has been intensively used for dynamic aperture calculations with beam–beam interaction for RHIC. Recently, proton spin tracking and electron energy loss due to synchrotron radiation were added. In this article, I will present the code architecture,more »physics models, and some selected examples of its applications to RHIC and a future electron-ion collider design eRHIC.« less

  11. Ship response using a compact wave spectrum model 

    E-Print Network [OSTI]

    Linn, Larry Donald

    1985-01-01

    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...

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

    DOE Patents [OSTI]

    Hutton, Andrew (Yorktown, VA)

    2009-03-03

    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.

  13. 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...

  14. Two Stellar Components in the Halo of the Milky Way

    E-Print Network [OSTI]

    D. Carollo; T. C. Beers; Y. S. Lee; M. Chiba; J. E. Norris; R. Wilhelm; T. Sivarani; B. Marsteller; J. A. Munn; C. A. L. Bailer-Jones; P. Re Fiorentin; D. G. York

    2007-12-16

    The halo of the Milky Way provides unique elemental abundance and kinematic information on the first objects to form in the Universe, which can be used to tightly constrain models of galaxy formation and evolution. Although the halo was once considered a single component, evidence for its dichotomy has slowly emerged in recent years from inspection of small samples of halo objects. Here we show that the halo is indeed clearly divisible into two broadly overlapping structural components -- an inner and an outer halo -- that exhibit different spatial density profiles, stellar orbits and stellar metallicities (abundances of elements heavier than helium). The inner halo has a modest net prograde rotation, whereas the outer halo exhibits a net retrograde rotation and a peak metallicity one-third that of the inner halo. These properties indicate that the individual halo components probably formed in fundamentally different ways, through successive dissipational (inner) and dissipationless (outer) mergers and tidal disruption of proto-Galactic clumps.

  15. ASPCAP: The Apogee Stellar Parameter and Chemical Abundances Pipeline

    E-Print Network [OSTI]

    Pérez, Ana E García; Holtzman, Jon A; Shetrone, Matthew; Mészáros, Szabolcs; Bizyaev, Dmitry; Carrera, Ricardo; Cunha, Katia; García-Hernández, D A; Johnson, Jennifer A; Majewski, Steven R; Nidever, David L; Schiavon, Ricardo P; Shane, Neville; Smith, Verne V; Sobeck, Jennifer; Troup, Nicholas; Zamora, Olga; Bovy, Jo; Eisenstein, Daniel J; Feuillet, Diane; Frinchaboy, Peter M; Hayden, Michael R; Hearty, Fred R; Nguyen, Duy C; O'Connell, Robert W; Pinsonneault, Marc H; Weinberg, David H; Wilson, John C; Zasowski, Gail

    2015-01-01

    The Apache Point Observatory Galactic Evolution Experiment (APOGEE) has built the largest moderately high-resolution (R=22, 500) spectroscopic map of the stars across the Milky Way, and including dust-obscured areas. The APOGEE Stellar Parameter and Chemical Abundances Pipeline (ASPCAP) is the software developed for the automated analysis of these spectra. ASPCAP determines atmospheric parameters and chemical abundances from observed spectra by comparing observed spectra to libraries of theoretical spectra, using chi-2 minimization in a multidimensional parameter space. The package consists of a fortran90 code that does the actual minimization, and a wrapper IDL code for book-keeping and data handling. This paper explains in detail the ASPCAP components and functionality, and presents results from a number of tests designed to check its performance. ASPCAP provides stellar effective temperatures, surface gravities, and metallicities precise to 2%, 0.1 dex, and 0.05 dex, respectively, for most APOGEE stars, wh...

  16. The Dynamical Inverse Problem for Axisymmetric Stellar Systems

    E-Print Network [OSTI]

    David Merritt

    1996-06-05

    The standard method of modelling axisymmetric stellar systems begins from the assumption that mass follows light. The gravitational potential is then derived from the luminosity distribution, and a unique two-integral distribution function f(E,Lz) that generates the stellar density in this potential is found. We show that the gravitational potential can instead be generated directly from the velocity data in a two-integral galaxy, thus allowing one to drop the assumption that mass follows light. The rotational velocity field can also be recovered in a model-independent way. We present regularized algorithms for carrying out the inversions and test them by application to pseudo-data from a family of oblate models.

  17. 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

    1998-11-24

    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.

  18. Dislocations in magnetohydrodynamic waves in a stellar atmosphere

    E-Print Network [OSTI]

    Ariste, A López; Khomenko, E

    2013-01-01

    We describe the presence of wavefront dislocations in magnetohydrodynamic waves in stratified stellar atmospheres. Scalar dislocations such as edges and vortices can appear in Alfv\\'en waves, as well as in general magneto-acoustic waves. We detect those dislocations in observations of magnetohydrodynamic waves in sunspots in the solar chromosphere. Through the measured charge of all the dislocations observed, we can give for the first time estimates of the modal contribution in the waves propagating along magnetic fields in solar sunspots.

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

    SciTech Connect (OSTI)

    Lu, Louise; Sick, Volker; Frank, Jonathan H.

    2013-09-01

    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.

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

    E-Print Network [OSTI]

    K. A. Postnov; A. M. Cherepashchuk

    2004-01-22

    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.

  1. Stars In Other Universes: Stellar structure with different fundamental constants

    E-Print Network [OSTI]

    Fred C. Adams

    2008-07-23

    Motivated by the possible existence of other universes, with possible variations in the laws of physics, this paper explores the parameter space of fundamental constants that allows for the existence of stars. To make this problem tractable, we develop a semi-analytical stellar structure model that allows for physical understanding of these stars with unconventional parameters, as well as a means to survey the relevant parameter space. In this work, the most important quantities that determine stellar properties -- and are allowed to vary -- are the gravitational constant $G$, the fine structure constant $\\alpha$, and a composite parameter $C$ that determines nuclear reaction rates. Working within this model, we delineate the portion of parameter space that allows for the existence of stars. Our main finding is that a sizable fraction of the parameter space (roughly one fourth) provides the values necessary for stellar objects to operate through sustained nuclear fusion. As a result, the set of parameters necessary to support stars are not particularly rare. In addition, we briefly consider the possibility that unconventional stars (e.g., black holes, dark matter stars) play the role filled by stars in our universe and constrain the allowed parameter space.

  2. Stellar and Gaseous Disk Structures in Cosmological Galaxy Equilibrium Models

    E-Print Network [OSTI]

    Rathaus, Ben

    2015-01-01

    We present "radially-resolved-equilibrium-models" for the growth of stellar and gaseous disks in cosmologically accreting massive halos. Our focus is on objects that evolve to redshifts $z\\sim 2$. We solve the time-dependent equations that govern the radially dependent star-formation rates, inflows and outflows from and to the inter- and circum-galactic medium, and inward radial gas flows within the disks. The stellar and gaseous disks reach equilibrium configurations on dynamical time scales much shorter than variations in the cosmological dark matter halo growth and baryonic accretions rates. We show analytically that mass and global angular momentum conservation naturally give rise to exponential gas and stellar disks over many radial length scales. The gaseous disks are more extended as set by the condition Toomre $Q<1$ for star-formation. The disks rapidly become baryon dominated. For massive, $5\\times 10^{12}M_\\odot$ halos at redshift $z=2$, we reproduced the typical observed star-formation rates of ...

  3. The stellar wind velocity field of HD 77581

    E-Print Network [OSTI]

    Manousakis, A

    2015-01-01

    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.

  4. Turbulent Convection in Stellar Interiors. II. The Velocity Field

    E-Print Network [OSTI]

    David Arnett; Casey Meakin; P. A. Young

    2008-11-25

    We analyze stellar convection with the aid of 3D hydrodynamic simulations, introducing the turbulent cascade into our theoretical analysis. We devise closures of the Reynolds-decomposed mean field equations by simple physical modeling of the simulations (we relate temperature and density fluctuations via coefficients); the procedure (CABS, Convection Algorithms Based on Simulations) is terrestrially testable and is amenable to systematic improvement. We develop a turbulent kinetic energy equation which contains both nonlocal and time dependent terms, and is appropriate if the convective transit time is shorter than the evolutionary time scale. The interpretation of mixing-length theory (MLT) as generally used in astrophysics is incorrect; MLT forces the mixing length to be an imposed constant. Direct tests show that the damping associated with the flow is that suggested by Kolmogorov. The eddy size is approximately the depth of the convection zone, and this dissipation length corresponds to the "mixing length". New terms involving local heating by turbulent dissipation should appear in the stellar evolution equations. The enthalpy flux ("convective luminosity") is directly connected to the buoyant acceleration, and hence the velocity scale. MLT tends to systematically underestimate this velocity scale. Quantitative comparison with a variety of 3D simulations reveals a previously recognized consistency. Examples of application to stellar evolution will be presented in subsequent papers in this series.

  5. Diagnostics of inhomogeneous stellar jets: Convolution effects and data reconstruction

    E-Print Network [OSTI]

    F. De Colle; C. del Burgo; A. C. Raga

    2008-05-05

    CONTEXT: In the interpretation of stellar jet observations, the physical parameters are usually determined from emission line ratios, obtained from spectroscopic observations or using the information contained in narrow band images. The basic hypothesis in the interpretation of the observations is that the emitting region is homogeneous along the line of sight. Actually, stellar jets are in general not homogeneous, and therefore line of sight convolution effects may lead to the main uncertainty in the determination of the physical parameters. AIMS: This paper is aimed at showing the systematic errors introduced when assuming an homogeneous medium, and studying the effect of an inhomogeneous medium on plasma diagnostics for the case of a stellar jet. In addition, we explore how to reconstruct the volumetric physical parameters of the jet (i. e., with dependence both across and along the line of sight). METHODS: We use standard techniques to determine the physical parameters, i. e., the electron density, temperature and hydrogen ionisation fraction across the jet, and a multi-Gaussian method to invert the Abel transform and determine the reconstructed physical structure. RESULTS: When assuming an homogeneous medium the physical parameters, integrated along the line of sight, do not represent the average of the true values, and do not have a clear physical interpretation. We show that when some information is available on the emissivity profile across the jet, it is then possible to obtain appropriate derivations of the electron density, temperature and ionisation fraction.

  6. A nonextensive view of the stellar braking indices

    E-Print Network [OSTI]

    de Freitas, D B; Soares, B B; Silva, J R P

    2015-01-01

    The present work is based on a description for the angular mometum loss rate due to magnetic braking for main-sequence stars on the relationship between stellar rotation and age. In general, this loss rate denoted by $\\mathrm dJ/\\mathrm dt$ depends on angular velocity $\\Omega$ in the form $\\mathrm dJ/\\mathrm dt\\propto\\Omega^{q}$, where $q$ is a parameter extracted from nonextensive statistical mechanics. Already, in context of stellar rotation, this parameter is greater than unity and it is directly related to the braking index. For $q$ equal to unity, the scenario of saturation of the magnetic field is recovered, otherwise $q$ indicates an unsaturated field. This new approach have been proposed and investigated by de Freitas \\& De Medeiros for unsaturated field stars. In present work, we propose a nonextensive approach for the stellar rotational evolution based on the Reiners \\& Mohanthy model. In this sense, we developed a nonextensive version of Reiners \\& Mohanthy torque and also compare this ...

  7. A Unified Computational Model for Solar and Stellar Flares

    E-Print Network [OSTI]

    Allred, Joel C; Carlsson, Mats

    2015-01-01

    We present a unified computational framework which can be used to describe impulsive flares on the Sun and on dMe stars. The models assume that the flare impulsive phase is caused by a beam of charged particles that is accelerated in the corona and propagates downward depositing energy and momentum along the way. This rapidly heats the lower stellar atmosphere causing it to explosively expand and dramatically brighten. Our models consist of flux tubes that extend from the sub-photosphere into the corona. We simulate how flare-accelerated charged particles propagate down one-dimensional flux tubes and heat the stellar atmosphere using the Fokker-Planck kinetic theory. Detailed radiative transfer is included so that model predictions can be directly compared with observations. The flux of flare-accelerated particles drives return currents which additionally heat the stellar atmosphere. These effects are also included in our models. We examine the impact of the flare-accelerated particle beams on model solar and...

  8. Evolution of stellar disk truncations since z=1

    E-Print Network [OSTI]

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

    2008-07-26

    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.

  9. Evolution of stellar disk truncations since z=1

    E-Print Network [OSTI]

    Trujillo, Ignacio; Bakos, Judit; Beckman, John; Pohlen, Michael

    2008-01-01

    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.

  10. Stellar populations of massive elliptical galaxies in very rich clusters

    E-Print Network [OSTI]

    Carretero, C; Beckman, J E

    2006-01-01

    We present a detailed stellar population analysis of 27 massive elliptical galaxies within 4 very rich clusters at redshift z~0.2: A115, A655, A963 and A2111. Using the new, high-resolution stellar populations models developed in our group, we obtained accurate estimates of the mean luminosity-weighted ages and relative abundances of CN, Mg and Fe. We have found that [CN/H] and [Mg/H] are correlated with sigma while [Fe/H] and Log(age) are not. In addition, both abundance ratios [CN/Fe] and [Mg/Fe] increase with sigma. Furthermore, the [CN/H]-sigma and [CN/Fe]-sigma slopes are steeper for galaxies in very rich clusters than those in the less dense Virgo and Coma clusters. On the other hand, [Mg/H]-sigma and [Mg/Fe]-sigma slopes keep constant as functions of the environment. Our results are compatible with a scenario in which the stellar populations of massive elliptical galaxies, independently of their environment and mass, had formation timescales shorter than ~1 Gyr. This result implies that massive ellipti...

  11. The dust grain size - stellar luminosity trend in debris discs

    E-Print Network [OSTI]

    Pawellek, Nicole

    2015-01-01

    The cross section of material in debris discs is thought to be dominated by the smallest grains that can still stay in bound orbits despite the repelling action of stellar radiation pressure. Thus the minimum (and typical) grain size $s_\\text{min}$ is expected to be close to the radiation pressure blowout size $s_\\text{blow}$. Yet a recent analysis of a sample of Herschel-resolved debris discs showed the ratio $s_\\text{min}/s_\\text{blow}$ to systematically decrease with the stellar luminosity from about ten for solar-type stars to nearly unity in the discs around the most luminous A-type stars. Here we explore this trend in more detail, checking how significant it is and seeking to find possible explanations. We show that the trend is robust to variation of the composition and porosity of dust particles. For any assumed grain properties and stellar parameters, we suggest a recipe of how to estimate the "true" radius of a spatially unresolved debris disc, based solely on its spectral energy distribution. The r...

  12. On the interaction of microquasar jets with stellar winds

    E-Print Network [OSTI]

    M. Perucho; V. Bosch-Ramon

    2008-02-08

    Strong interactions between jets and stellar winds at binary system spatial scales could occur in high-mass microquasars. We study here, mainly from a dynamical but also a radiative point of view, the collision between a dense stellar wind and a mildly relativistic hydrodynamical jet of supersonic nature.}{We have performed numerical 2-dimensional simulations of jets, with cylindrical and planar (slab) symmetry, crossing the stellar wind material. From the results of the simulations, we derive estimates of the particle acceleration efficiency, using first order Fermi acceleration theory, and give some insight on the possible radiative outcomes. We find that, during jet launching, the jet head generates a strong shock in the wind. During and after this process, strong recollimation shocks can occur due to the initial overpressure of the jet with its environment. The conditions in all these shocks are convenient to accelerate particles up to $\\sim$ TeV energies, which can lead to leptonic (synchrotron and inverse Compton) and hadronic (proton-proton) radiation. In principle, the cylindrical jet simulations show that the jet is stable, and can escape from the system even for relatively low power. However, when accounting for the wind ram pressure, the jet can be bent and disrupted for power $\\la 10^{36}$ erg s$^{-1}$.

  13. Modelling the Spectral Energy Distribution of Compact Luminous Infrared Galaxies: Constraints from High Frequency Radio Data

    E-Print Network [OSTI]

    O. R. Prouton; A. Bressan; M. Clemens; A. Franceschini; G. L. Granato; L. Silva

    2004-03-24

    We have performed 23 GHz VLA observations of 7 compact, luminous infrared galaxies, selected to have evidence of starburst activity. New and published multi-frequency data are combined to obtain the spectral energy distributions of all 7 galaxies from the near-infrared to the radio (at 1.4 GHz). These SEDs are compared with new models, for dust enshrouded galaxies, which account for both starburst and AGN components. In all 7 galaxies the starburst provides the dominant contribution to the infrared luminosity; in 4 sources no contribution from an AGN is required. Although AGN may contribute up to 50 percent of the total far--infrared emission, the starbursts always dominate in the radio. The SEDs of most of our sources are best fit with a very high optical depth of (>=50) at 1 micron. The scatter in the far-infrared/radio correlation, found among luminous IRAS sources, is due mainly to the different evolutionary status of their starburst components. The short time-scale of the star formation process amplifies the delay between the far-infrared and radio emission. This becomes more evident at low radio frequencies (below about 1 GHz) where synchrotron radiation is the dominant process. In the far-infrared (at wavelengths shorter than 100 micron) an additional source of scatter is provided by AGN, where present. AGN may be detected in the near-infrared by the absence of the knee, typical of stellar photospheres. However, near-infrared data alone cannot constrain the level at which AGN contribute because the interpretation of their observed properties, in this wave-band, depends strongly on model parameters.

  14. 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 trials, production rates, and soil compaction impacts of two systems for harvesting western juniper (Juniperus. Stump to deck harvesting costs ranged from $32.15 to $49.48/ton for the conventional system and from $60

  15. Sur les surfaces lorentziennes compactes sans points conjugus

    E-Print Network [OSTI]

    Mounoud, Pierre

    Sur les surfaces lorentziennes compactes sans points conjugués CHRISTOPHE BAVARD PIERRE MOUNOUD Nous prouvons l'existence de métriques sans points conjugués dans toute com- posante connexe de l lorentziens sans points conjugués non plats contraste avec la situation riemannienne (théorème de E. Hopf). We

  16. Fast and compact elliptic-curve cryptography Mike Hamburg

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    relatively compact. For example, on Intel Sandy Bridge, a curve with about 2250 points produces a signa- ture a difficult choice for less powerful systems such as embedded devices and smart phones. Cryptography Research Bridge microarchitecture. While RSA-2048 is still con- siderably faster at approximately 98k (even

  17. COMPACT AC-OPERATORS Ian Doust and Byron L. Walden

    E-Print Network [OSTI]

    Doust, Ian

    (H). This theorem has a direct analogue for compact scalar-type spectral operators acting on a Banach space X in section 4, the most natural order turns out to be difficult to* * work ______________ 1991 Mathematics was supported by the Australian Research Council

  18. THE GENERALIZED RIEMANN INTEGRAL ON LOCALLY COMPACT SPACES

    E-Print Network [OSTI]

    Edalat, Abbas

    THE GENERALIZED RIEMANN INTEGRAL ON LOCALLY COMPACT SPACES Abbas Edalat Sara Negri Department on the theory of the generalized Riemann integral to the setting of bounded or locally nite measures on locally is the given locally nite measure. The generalized Riemann integral is de ned for bounded functions

  19. Compact Explanation of Data Fusion Decisions Xin Luna Dong 1

    E-Print Network [OSTI]

    Greenberg, Albert

    Compact Explanation of Data Fusion Decisions Xin Luna Dong 1 , Divesh Srivastava 2 AT&T Labs-- Data fusion aims at resolving conflicts between different sources when integrating their data. Recent fusion techniques find the truth by iterative MAP (Maximum A Pos- teriori) analysis that reasons about

  20. ULTRA-COMPACT ACCELERATOR TECHNOLOGIES FOR APPLICATION IN NUCLEAR TECHNIQUES

    SciTech Connect (OSTI)

    Sampayan, S; Caporaso, G; Chen, Y; Carazo, V; Falabella, S; Guethlein, G; Guse, S; Harris, J R; Hawkins, S; Holmes, C; Krogh, M; Nelson, S; Paul, A C; Pearson, D; Poole, B; Schmidt, R; Sanders, D; Selenes, K; Sitaraman, S; Sullivan, J; Wang, L; Watson, J

    2009-06-11

    We report on compact accelerator technology development for potential use as a pulsed neutron source quantitative post verifier. The technology is derived from our on-going compact accelerator technology development program for radiography under the US Department of Energy and for a clinic sized compact proton therapy systems under an industry sponsored Cooperative Research and Development Agreement. The accelerator technique relies on the synchronous discharge of a prompt pulse generating stacked transmission line structure with the beam transit. The goal of this technology is to achieve {approx}10 MV/m gradients for 10s of nanoseconds pulses and to {approx}100 MV/m gradients for {approx}1 ns systems. As a post verifier for supplementing existing x-ray equipment, this system can remain in a charged, stand-by state with little or no energy consumption. We detail the progress of our overall component development effort with the multilayer dielectric wall insulators (i.e., the accelerator wall), compact power supply technology, kHz repetition-rate surface flashover ion sources, and the prompt pulse generation system consisting of wide-bandgap switches and high performance dielectric materials.

  1. 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

    2012-12-01

    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.

  2. Compact anhydrous HCl to aqueous HCl conversion system

    SciTech Connect (OSTI)

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

    1993-01-01

    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.

  3. Compact Implementations of BLAKE-32 and BLAKE-64 on FPGA

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    , Tsukuba, Ibaraki, 305-8573, Japan jeanluc.beuchat@gmail.com, okamoto@risk.tsukuba.ac.jp, yamazaki@cipher.risk pipeline stages, and to achieve high clock frequencies. With careful scheduling, we completely avoid pipeline bubbles. For the time being, the designs presented in this work are the most compact ones for any

  4. Compact anhydrous HCl to aqueous HCl conversion system

    DOE Patents [OSTI]

    Grossman, M.W.; Speer, R.

    1993-06-01

    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.

  5. A Compact and Scalable RNS Architecture Pedro Miguens Matutino

    E-Print Network [OSTI]

    Sousa, Leonel

    A Compact and Scalable RNS Architecture Pedro Miguens Matutino ISEL / INESC-ID / IST, Technical a unified architecture for designing Residue Number System (RNS) based processors for moduli sets with an arbitrary number of channels. Recently, new RNS moduli sets have been proposed in order to increase

  6. 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

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

    DOE Patents [OSTI]

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

    2000-01-01

    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.

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

    E-Print Network [OSTI]

    Strathclyde, University of

    involving teams at the Friedrich-Schiller-Universität, Jena, Germany, and Stellenbosch University in South laser pulses can be fired into plasma to create a wake and its huge electric fields can be harnessed you a powerful scientific tool for the price of a laser." The project to develop compact light sources

  9. 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

  10. Path to Market for Compact Modular Fusion Power Cores

    E-Print Network [OSTI]

    Precedents? Small number of private fusion companies starting up, filing patents and finding editions Lead author Grounded in DOE program #12;12/13/11 5 Path to market 'next step' Springer Energy Brief: 'Path to Market for Compact Modular Fusion Power' Soliciting wider input from energy, business

  11. Embedding the bicyclic semigroup into countably compact topological semigroups

    E-Print Network [OSTI]

    Banakh, Taras; Gutik, Oleg

    2008-01-01

    We study algebraic and topological properties of topological semigroups containing a copy of the bicyclic semigroup $C(p,q)$. We prove that each topological semigroup $S$ with pseudocompact square contains no dense copy of $C(p,q)$. On the other hand, we construct a consistent example of a Tychonov countably compact semigroup containing a copy of $C(p,q)$.

  12. 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

  13. 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

    2013-01-01

    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.

  14. Ceramographic Examinations of Irradiated AGR-1 Fuel Compacts

    SciTech Connect (OSTI)

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

    2012-09-01

    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.

  15. Ceramographic Examinations of Irradiated AGR-1 Fuel Compacts

    SciTech Connect (OSTI)

    Paul Demkowicz; Scott Ploger; John Hunn

    2012-05-01

    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.

  16. 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)

    2013-05-01

    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.

  17. AN ULTRA-LOW-MASS AND SMALL-RADIUS COMPACT OBJECT IN 4U 1746-37?

    SciTech Connect (OSTI)

    Li, Zhaosheng; Qu, Zhijie; Guo, Yanjun; Xu, Renxin; Chen, Li; Qu, Jinlu

    2015-01-01

    Photospheric radius expansion (PRE) bursts have already been used to constrain the masses and radii of neutron stars. RXTE observed three PRE bursts in 4U 1746-37, all with low touchdown fluxes. We discuss here the possibility of a low-mass neutron star in 4U 1746-37 because the Eddington luminosity depends on stellar mass. With typical values of hydrogen mass fraction and color correction factor, a Monte Carlo simulation was applied to constrain the mass and radius of a neutron star in 4U 1746-37. 4U 1746-37 has a high inclination angle. Two geometric effects, the reflection of the far-side accretion disk and the obscuration of the near-side accretion disk, have also been included in the mass and radius constraints of 4U 1746-37. If the reflection of the far-side accretion disk is accounted for, a low-mass compact object (mass of 0.41 ± 0.14 M {sub ?} and radius of 8.73 ± 1.54 km at 68% confidence) exists in 4U 1746-37. If another effect operated, 4U 1746-37 may contain an ultra-low-mass and small-radius object (M = 0.21 ± 0.06 M {sub ?}, R = 6.26 ± 0.99 km at 68% confidence). Combining all possibilities, the mass of 4U 1746-37 is 0.41{sub ?0.30}{sup +0.70} M{sub ?} at 99.7% confidence. For such low-mass neutron stars, it could be reproduced by a self-bound compact star, i.e., a quark star or quark-cluster star.

  18. A Permanent-Magnet Microwave Ion Source for a Compact High-Yield Neutron Generator

    E-Print Network [OSTI]

    Waldmann, Ole

    2011-01-01

    A Permanent-Magnet Microwave Ion Source for a Compact High-A Permanent-Magnet Microwave Ion Source for a Compact High-on the development of a microwave ion source that will be

  19. Acoustic emission and compaction creep of quartz sand at subcritical stress 

    E-Print Network [OSTI]

    Lenz, Steven Christopher

    2002-01-01

    Time-dependent fluid-assisted mechanisms such as stress-induced dissolution and subcritical crack growth play an important role in porosity reduction and compaction of granular material in nature. Previous compaction creep experiments on loosely...

  20. 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...

  1. The Heavy Ion Fusion Virtual National Laboratory Status and new physics directions for heavy-ion-driven

    E-Print Network [OSTI]

    for compact driver-scale injectors. Two LLNL injector test stands #12;The Heavy Ion Fusion Virtual NationalThe Heavy Ion Fusion Virtual National Laboratory Status and new physics directions for heavy-ion-driven high energy density physics and fusion* G. Logan, F. Bieniosek, C. Celata, E. Henestroza, J. Kwan, E. P

  2. National Institutes of Health Current National Institute

    E-Print Network [OSTI]

    Rau, Don C.

    Library of Medicine John E. Fogarty International Center for Advanced Study in National Center National Institute of Nursing Research National Library of Medicine John E. Fogarty International CenterNational Institutes of Health Current National Institute of Arthritis and Musculoskeletal and Skin

  3. Mime: Compact, Low-Power 3D Gesture Sensing for Interaction with Head-Mounted Displays

    E-Print Network [OSTI]

    Goyal, Vivek K

    Mime: Compact, Low-Power 3D Gesture Sensing for Interaction with Head-Mounted Displays Andrea Colac of Technology Figure 1: Mime is a compact, low power sensor for 3D gestural control of head mounted displays, a compact, low-power 3D sensor for unen- cumbered free-form, single-handed gestural interaction with head

  4. eCAM: Ultra Compact, High Data-Rate Wireless Sensor Node with a Miniature Camera

    E-Print Network [OSTI]

    Shinozuka, Masanobu

    eCAM: Ultra Compact, High Data-Rate Wireless Sensor Node with a Miniature Camera Chulsung Park Email: {chulsung, phchou}@uci.edu Abstract-- eCAM is an ultra-compact, high data-rate wireless sensor to the theoretical peak performance. In this demo, we propose eCAM, an ultra compact, high data-rate wireless sensor

  5. Fourth Order Compact Difference Scheme for 3D Convection Diffusion Equation with

    E-Print Network [OSTI]

    Zhang, Jun

    Fourth Order Compact Difference Scheme for 3D Convection Diffusion Equation with Boundary Layers University, Washington, DC 20052, USA January 13, 2000 Abstract We present a fourth order compact finite and computational efficiency of the fourth order compact dif­ ference scheme with that of the standard central

  6. Late Fusion of Compact Composite Descriptors for Retrieval from Heterogeneous Image Databases

    E-Print Network [OSTI]

    Arampatzis, Avi

    Late Fusion of Compact Composite Descriptors for Retrieval from Heterogeneous Image Databases-search. While early fusion has been common, late fu- sion still remains an under-explored possibility. Compact University of Thrace Xanthi, Greece schatzic@ee.duth.gr, avi@ee.duth.gr ABSTRACT Compact composite

  7. 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

  8. Acoustic emission and velocities associated with the formation of compaction bands in sandstone

    E-Print Network [OSTI]

    Fortin, Jérôme

    Acoustic emission and velocities associated with the formation of compaction bands in sandstone Je the development of compaction bands in Bleurswiller sandstone, which has a porosity of 25%. Results were obtained of compaction bands in sandstone, J. Geophys. Res., 111, B10203, doi:10.1029/2005JB003854. 1. Introduction [2

  9. 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

    2010-10-01

    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.

  10. The Next Generation Virgo Cluster Survey. X. Properties of Ultra-Compact Dwarfs in the M87, M49 and M60 Regions

    E-Print Network [OSTI]

    Liu, Chengze; Cote, Patrick; Ferrarese, Laura; Jordan, Andres; Mihos, J Christopher; Zhang, Hong-Xin; Munoz, Roberto P; Puzia, Thomas H; Lancon, Ariane; Gwyn, Stephen; Cuillandre, Jean-Charles; Blakeslee, John P; Boselli, Alessandro; Durrell, Patrick R; Duc, Pierre-Alain; Guhathakurta, Puragra; MacArthur, Lauren A; Mei, Simona; Sanchez-Janssen, Ruben; Xu, Haiguang

    2015-01-01

    We use imaging from the Next Generation Virgo cluster Survey (NGVS) to present a comparative study of ultra-compact dwarf (UCD) galaxies associated with three prominent Virgo sub-clusters: those centered on the massive, red-sequence galaxies M87, M49 and M60. We show how UCDs can be selected with high completeness using a combination of half-light radius and location in color-color diagrams ($u^*iK_s$ or $u^*gz$). Although the central galaxies in each of these sub-clusters have nearly identical luminosities and stellar masses, we find large differences in the sizes of their UCD populations, with M87 containing ~3.5 and 7.8 times more UCDs than M49 and M60, respectively. The relative abundance of UCDs in the three regions scales in proportion to sub-cluster mass, as traced by X-ray gas mass, total gravitating mass, number of globular clusters, and number of nearby galaxies. We find that the UCDs are predominantly blue in color, with ~85% of the UCDs having colors similar to blue GCs and stellar nuclei of dwarf...

  11. Estimation of stellar atmospheric parameters from SDSS/SEGUE spectra

    E-Print Network [OSTI]

    P. Re Fiorentin; C. A. L. Bailer-Jones; Y. S. Lee; T. C. Beers; T. Sivarani; R. Wilhelm; C. Allende Prieto; J. E. Norris

    2007-03-13

    We present techniques for the estimation of stellar atmospheric parameters (Teff,logg,[Fe/H]) for stars from the SDSS/SEGUE survey. The atmospheric parameters are derived from the observed medium-resolution (R=2000) stellar spectra using non-linear regression models trained either on (1) pre-classified observed data or (2) synthetic stellar spectra. In the first case we use our models to automate and generalize parametrization produced by a preliminary version of the SDSS/SEGUE Spectroscopic Parameter Pipeline (SSPP). In the second case we directly model the mapping between synthetic spectra (derived from Kurucz model atmospheres) and the atmospheric parameters, independently of any intermediate estimates. After training, we apply our models to various samples of SDSS spectra to derive atmospheric parameters, and compare our results with those obtained previously by the SSPP for the same samples. We obtain consistency between the two approaches, with RMS deviations of 150K in Teff, 0.35dex in logg, and 0.22dex in [Fe/H]. The models are applied to pre-processed spectra, either via Principal Components Analysis or a Wavelength Range Selection method, which employs a subset of the full 3850-9000A spectral range. This is both for computational reasons, and because it delivers higher accuracy. From an analysis of cluster candidates with available SDSS spectroscopy (M15, M13, M2, and NGC2420), we find evidence for small systematic offsets in Teff and/or logg for the atmospheric parameter estimates from the model trained on real data with the SSPP. Thus, this model turns out to derive more precise, but less accurate, atmospheric parameters than the model trained on synthetic data.

  12. Stellar populations of massive elliptical galaxies in very rich clusters

    E-Print Network [OSTI]

    C. Carretero; A. Vazdekis; J. E. Beckman; .

    2006-12-05

    We present a detailed stellar population analysis of 27 massive elliptical galaxies within 4 very rich clusters at redshift z~0.2: A115, A655, A963 and A2111. Using the new, high-resolution stellar populations models developed in our group, we obtained accurate estimates of the mean luminosity-weighted ages and relative abundances of CN, Mg and Fe. We have found that [CN/H] and [Mg/H] are correlated with sigma while [Fe/H] and Log(age) are not. In addition, both abundance ratios [CN/Fe] and [Mg/Fe] increase with sigma. Furthermore, the [CN/H]-sigma and [CN/Fe]-sigma slopes are steeper for galaxies in very rich clusters than those in the less dense Virgo and Coma clusters. On the other hand, [Mg/H]-sigma and [Mg/Fe]-sigma slopes keep constant as functions of the environment. Our results are compatible with a scenario in which the stellar populations of massive elliptical galaxies, independently of their environment and mass, had formation timescales shorter than ~1 Gyr. This result implies that massive elliptical galaxies have evolved passively since, at least, as long ago as z~2. For a given galaxy mass the duration of star formation is shorter in those galaxies belonging to more dense environments; whereas the mass-metallicity relation appears to be also a function of the cluster properties: the denser the environment is, the steeper are the correlations. Finally, we show that the abundance ratios [CN/Fe] and [Mg/Fe] are the key "chemical clocks" to infer the star formation history timescales in ellipticals. In particular, [Mg/Fe] provides an upper limit for those formation timescales, while [CN/Fe] apperars to be the most suitable parameter to resolve them in elliptical galaxies with sigma<300 km/s.

  13. Ultra-compact In-Line Scattering Polarimetry

    E-Print Network [OSTI]

    Müller, J P Balthasar; Capasso, Federico

    2015-01-01

    The need for complex optical systems and special materials have so far prevented polarization measurements from realizing their full scientific potential and achieving widespread use in technology. We demonstrate here a nanotechnology-based method for non-destructive polarization measurements using a single ultra-compact optical element and simultaneous co-planar intensity measurements. The method is based on a highly polarization-dependent scattered field, which is here implemented using a nano-antenna array. Our device provides a polarization state measurement accurately matching that of a state-of-the art commercial rotating waveplate polarimeter across the full Poincar\\'e sphere, while offering far superior speed, stability and compactness. Our concept opens up the possibility of high-performance monolithically integrated polarization sensors adaptable to most of the electromagnetic spectrum.

  14. Nonlinear Sigma Models with Compact Hyperbolic Target Spaces

    E-Print Network [OSTI]

    Gubser, Steven; Schoenholz, Samuel S; Stoica, Bogdan; Stokes, James

    2015-01-01

    We explore the phase structure of nonlinear sigma models with target spaces corresponding to compact quotients of hyperbolic space, focusing on the case of a hyperbolic genus-2 Riemann surface. The continuum theory of these models can be approximated by a lattice spin system which we simulate using Monte Carlo methods. The target space possesses interesting geometric and topological properties which are reflected in novel features of the sigma model. In particular, we observe a topological phase transition at a critical temperature, above which vortices proliferate, reminiscent of the Kosterlitz-Thouless phase transition in the $O(2)$ model. Unlike in the $O(2)$ case, there are many different types of vortices, suggesting a possible analogy to the Hagedorn treatment of statistical mechanics of a proliferating number of hadron species. Below the critical temperature the spins cluster around six special points in the target space known as Weierstrass points. The diversity of compact hyperbolic manifolds suggest...

  15. A Compact Pulsed Power Generator for Capillary Pinch Experiments

    SciTech Connect (OSTI)

    Shukla, R.; Shyam, A. [Institute for Plasma Research, Near Indira Bridge, Bhat Village, Gandhinagar Gujarat 382428 (India)

    2006-01-05

    A compact pulsed power system is designed for conducting capillary pinch experiments for production of coherent electromagnetic radiations. The reported Pulsed power system is made very compact as well as portable by using solid dielectric pulse forming line. The system consists of a tesla transformer, which is of helical secondary and cylindrical-sheet single-turn primary. Tesla charges a pulse forming line made of cascade of 50 ohm transition lines, which are of high wattage as well as high voltage ratings under pulsed operation. The net impedance of this cable cascade is such that it is matched for a designed load, which is designed to operate at 250kV for 100ns pulse duration.

  16. Compact and mobile high resolution PET brain imager

    DOE Patents [OSTI]

    Majewski, Stanislaw (Yorktown, VA); Proffitt, James (Newport News, VA)

    2011-02-08

    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.

  17. The Dust Attenuation Curve versus Stellar Mass for Emission Line Galaxies at z ~ 2

    E-Print Network [OSTI]

    Zeimann, Gregory R; Gronwall, Caryl; Bridge, Joanna; Brooks, Hunter; Fox, Derek; Gawiser, Eric; Gebhardt, Henry; Hagen, Alex; Schneider, Donald P; Trump, Jonathan R

    2015-01-01

    We derive the mean wavelength dependence of stellar attenuation in a sample of 239 high redshift (1.90 & Conroy, who found that the wavelength dependence of attenuation varies with galaxy spectral type. However, we find no evidence of an extinction "bump" at 2175 A in any of the three stellar mass bins, or in the sample as a whole. We quantify the relation between the attenuation curve and stellar mass and discuss its implications.

  18. GPS based Compaction Technology June 24-26, 2008

    E-Print Network [OSTI]

    Drum AccelerationDrum Acceleration Automatic Closed-Loop Control Sensors #12;3 Frame Drum F xd FS FS FZ=mere2 ; =2f ; xd``=d2xd/dt2 FS>0: xd=xS=x FS =0: xd>xS Contact conditions: Force-Driven System & Stiffness-Data 1 Hertz Continuous Compaction Control Soil-Drum-Interaction 1 500 Hertz

  19. First Law of Mechanics for Compact Binaries on Eccentric Orbits

    E-Print Network [OSTI]

    Tiec, Alexandre Le

    2015-01-01

    Using the canonical Arnowitt-Deser-Misner Hamiltonian formalism, a "first law of mechanics" is established for binary systems of point masses moving along generic stable bound (eccentric) orbits. This relationship is checked to hold within the post-Newtonian approximation to general relativity, up to third (3PN) order. Several applications are discussed, including the use of gravitational self-force results to inform post-Newtonian theory and the effective one-body model for eccentric-orbit compact binaries.

  20. Stability of thin-shell interfaces inside compact stars

    E-Print Network [OSTI]

    Jonas P. Pereira; Jaziel G. Coelho; Jorge A. Rueda

    2015-01-05

    We use the thin-shell Darmois-Israel formalism to model and assess the stability of the interfaces separating phases, e.g. the core and the crust, within compact stars. We exemplify the relevance and non-triviality of this treatment in the simplest case of an incompressible star, in constant pressure phase transitions, and in the case of strange quark stars with crust.

  1. Simple and Compact Expressions for Neutrino Oscillation Probabilities in Matter

    E-Print Network [OSTI]

    Hisakazu Minakata; Stephen J Parke

    2015-05-07

    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 $\

  2. National Laboratory

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration wouldMass map shinesSolar Photovoltaic Solar PhotovoltaicBWXT Y-12 is preserving Y-12'sNational

  3. National Laboratory

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration wouldMass map shinesSolar Photovoltaic Solar PhotovoltaicBWXT Y-12 is preserving Y-12'sNational

  4. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefield MunicipalTechnical Report: AchievementsTemperatures Year 6 -FINALEnergy,Pacific Mort hwest National

  5. 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

    2006-12-21

    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.

  6. Ultra-Compact High-Efficiency Luminaire for General Illumination

    SciTech Connect (OSTI)

    Ted Lowes

    2012-04-08

    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.

  7. Tracer diffusion in compacted, water-saturated bentonite

    SciTech Connect (OSTI)

    Bourg, Ian C.; Sposito, Garrison; Bourg, Alain C.M.

    2005-08-04

    Compacted Na-bentonite clay barriers, widely used in theisolation of solid-waste landfills and other contaminated sites, havebeen proposed for a similar use in the disposal of high-level radioactivewaste. Molecular diffusion through the pore space in these barriers playsa key role in their performance, thus motivating recent measurements ofthe apparent diffusion coefficient tensor of water tracers in compacted,water-saturated Na-bentonites. In the present study, we introduce aconceptual model in which the pore space of water-saturated bentonite isdivided into 'macropore' and 'interlayer nanopore' compartments. Withthis model we determine quantitatively the relative contributions ofpore-network geometry (expressed as a geometric factor) and of thediffusive behavior of water molecules near montmorillonite basal surfaces(expressed as a contristivity factor) to the apparent diffusioncoefficient tensor. Our model predicts, in agreement with experiment,that the mean principal value of the apparent diffusion coefficienttensor follows a single relationship when plotted against the partialmontmorillonite dry density (mass of montmorillonite per combined volumeof montmorillonite and pore space). Using a single fitted parameter, themean principal geometric factor, our model successfully describes thisrelationship for a broad range of bentonite-water system, from dilute gelto highly-compacted bentonite with 80 percent of its pore water ininterlayer nanopores.

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

    Open Energy Info (EERE)

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

  9. Sandia National Laboratories | National Nuclear Security Administratio...

    National Nuclear Security Administration (NNSA)

    nuclear weapons Bay Area national labs team to tackle long-standing automotive hydrogen storage challenge Sandia National Laboratories chemist Mark Allendorf, shown here at...

  10. Integrated Plasma and Coil Optimization for Compact Stellarators D. J. Strickler 1), L. A. Berry 1), S. P. Hirshman 1), J. F. Lyon 1), D. A. Spong 1),

    E-Print Network [OSTI]

    Hudson, Stuart

    ), S. P. Hirshman 1), J. F. Lyon 1), D. A. Spong 1), D. E. Williamson 1), M. C. Zarnstorff 2), L-P. Ku. Lyon 1), D. A. Spong 1), D. E. Williamson 1), M. C. Zarnstorff 2), L-P. Ku 2), A. Brooks 2), S. R

  11. 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)

    2013-08-01

    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.

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

    E-Print Network [OSTI]

    T. Sakamoto; T. Hasegawa

    2006-10-29

    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.

  13. STELLAR ELEMENTAL ABUNDANCE PATTERNS: IMPLICATIONS FOR PLANET FORMATION

    SciTech Connect (OSTI)

    Chambers, J. E.

    2010-11-20

    The solar photosphere is depleted in refractory elements compared to most solar twins, with the degree of depletion increasing with an element's condensation temperature. Here, I show that adding 4 Earth masses of Earth-like and carbonaceous-chondrite-like material to the solar convection zone brings the Sun's composition into line with the mean value for the solar twins. The observed solar composition could have arisen if the Sun's convection zone accreted material from the solar nebula that was depleted in refractory elements due to the formation of the terrestrial planets and ejection of rocky protoplanets from the asteroid belt. Most solar analogs are missing 0-10 Earth masses of rocky material compared to the most refractory-rich stars, providing an upper limit to the mass of rocky terrestrial planets that they possess. The missing mass is correlated with stellar metallicity. This suggests that the efficiency of planetesimal formation increases with stellar metallicity. Stars with and without known giant planets show a similar distribution of abundance trends. If refractory depletion is a signature of the presence of terrestrial planets, this suggests that there is not a strong correlation between the presence of terrestrial and giant planets in the same system.

  14. Detection of Small Kuiper Belt Objects by Stellar Occultations

    E-Print Network [OSTI]

    R. Stevenson

    2007-12-10

    Knowledge of the Kuiper Belt is currently limited to those objects that can be detected directly. Objects with diameters less than $\\sim$10km reflect too little light to be detected. These smaller bodies could contain most of the mass in the Kuiper Belt while the abundance of these bodies may constrain the distribution of mass. The overall size distribution of bodies within the Kuiper Belt can also be inferred from the relative abundances of sub-km and larger bodies. Stellar occultations are already used to study dark objects in the Solar System, such as asteroids or planetary rings. Occultation by a KBO of a size comparable to, or larger than, that of the Fresnel Scale will result in Fresnel diffraction. Detection of diffraction effects requires fast multiple-star photometry, which will be conducted in July 2007 using the Orthogonal Parallel Transfer Imaging Camera (OPTIC) mounted on the University of Hawaii 2.2m telescope on Mauna Kea. This paper details how knowledge of the mass and structure of the outer Solar System may be obtained through the detection of serendipitous stellar occultations.

  15. FESAC White Paper Path to Market for Compact Systems July 2012 The Path to Market for Compact Modular Fusion Power Cores1

    E-Print Network [OSTI]

    Modular Fusion Power Cores1 S. Woodruff, R. L. Miller To take any new energy technology to market, we have: Market, Path, and Compact Fusion Systems. US Electricity Market "Electricity demand (including retail. Mattor, D. L. Stoulil, R. Miller, T. Marston. Woodruff Path to market for compact modular fusion power

  16. The Low-mass Stellar Population in L1641: Evidence for Environmental Dependence of the Stellar Initial Mass Function

    E-Print Network [OSTI]

    Hsu, Wen-Hsin; Allen, Lori; Hernandez, Jesus; Megeath, S T; Mosby, Gregory; Tobin, John J; Espaillat, Catherine

    2012-01-01

    We present results from an optical photometric and spectroscopic survey of the young stellar population in L1641, the low-density star-forming region of the Orion A cloud south of the Orion Nebula Cluster (ONC). Our goal is to determine whether L1641 has a large enough low-mass population to make the known lack of high-mass stars a statistically-significant demonstration of environmental dependence of the upper mass stellar initial mass function (IMF). Our spectroscopic sample consists of IR-excess objects selected from the Spitzer/IRAC survey and non-excess objects selected from optical photometry. We have spectral confirmation of 864 members, with another 98 probable members; of the confirmed members, 406 have infrared excesses and 458 do not. Assuming the same ratio of stars with and without IR excesses in the highly-extincted regions, L1641 may contain as many as ~1600 stars down to ~0.1 solar mass, comparable within a factor of two to the the ONC. Compared to the standard models of the IMF, L1641 is defi...

  17. 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.

  18. Development of a Compact Neutron Generator to be Used For Associated Particle Imaging Utilizing a RF-Driven Ion Source

    E-Print Network [OSTI]

    Wu, Ying

    2009-01-01

    compact neutron generators, semiconductor manufacturing, and neutral beam diagnostics and heating in fusion

  19. ON THE FORMATION OF MULTIPLE STELLAR POPULATIONS IN GLOBULAR CLUSTERS

    SciTech Connect (OSTI)

    Charlie, Conroy; Spergel, David N. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2011-01-01

    Nearly all globular clusters (GCs) studied to date show evidence for multiple stellar populations, in stark contrast to the conventional view that GCs are a mono-metallic, coeval population of stars. This generic feature must therefore emerge naturally within massive star cluster formation. Building on earlier work, we propose a simple physical model for the early evolution (several 10{sup 8} yr) of GCs. We consider the effects of stellar mass loss, Type II supernovae (SNe II) and prompt Type Ia supernovae (SNe Ia), ram pressure, and accretion from the ambient interstellar medium (ISM) on the development of a young GC's own gas reservoir. In our model, SNe II from a first generation of star formation clears the GC of its initial gas reservoir. Over the next several 10{sup 8} yr, mass lost from asymptotic giant branch stars and matter accreted from the ambient ISM collect at the center of the GC. This material must remain quite cool (T {approx} 10{sup 2} K), but does not catastrophically cool on a crossing time because of the high Lyman-Werner flux density in young GCs. The collection of gas within the GC must compete with ram pressure from the ambient ISM. After several 10{sup 8} yr, the Lyman-Werner photon flux density drops by more than three orders of magnitude, allowing molecular hydrogen and then stars to form. After this second generation of star formation, SNe II from the second generation and then prompt SNe Ia associated with the first generation maintain a gas-free GC, thereby ending the cycle of star formation events. Our model makes clear predictions for the presence or absence of multiple stellar populations within GCs as a function of GC mass and formation environment. While providing a natural explanation for the approximately equal number of first- and second-generation stars in GCs, substantial accretion from the ambient ISM may produce fewer chemically peculiar second-generation stars than are observed. Analyzing intermediate-age LMC clusters, we find for the first time evidence for a mass threshold of {approx}10{sup 4} M{sub sun} below which LMC clusters appear to be truly coeval. This threshold mass is consistent with our predictions for the mass at which ram pressure is capable of clearing gas from clusters in the LMC at the present epoch. Recently, claims have been made that multiple populations within GCs require that GCs form at the center of their own dark matter halos. We argue that such a scenario is implausible. Observations of the young and intermediate-age clusters in the LMC and M31 will provide strong constraints on our proposed scenario.

  20. 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

    2012-10-01

    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.

  1. The Solar-Stellar-MHD Connection We focus on the magnetic-field driven similarities,

    E-Print Network [OSTI]

    The Solar-Stellar-MHD Connection We focus on the magnetic-field driven similarities, and differences, between our Sun and other solar- type stars (the "solar-stellar connection"). Are the properties, and the build-up of a planetary magnetic field must have been achieved early on in the Sun's 4.5 billion year

  2. 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

  3. 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

  4. 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

  5. Mass Loss Rates, Ionization Fractions, Shock Velocities and Magnetic Fields of Stellar Jets

    E-Print Network [OSTI]

    Hartigan, Patrick

    Mass Loss Rates, Ionization Fractions, Shock Velocities and Magnetic Fields of Stellar Jets Patrick the initial conditions relevant to stellar jets, and we show how to estimate the ionization fractions and shock velocities in jets directly from observations of the strong emission lines in these flows

  6. Stellar Mass Buildup in Galaxies in the First 1.5 Gyr of the Universe

    E-Print Network [OSTI]

    Gonzalez, Valentino

    2012-01-01

    During the First Gyr of the Universe. 2.9.2 Star FormationThe Stellar Mass Density of the Universe as a Function ofStellar Mass iii of the Universe Density at z ? 7 2.8.3 How

  7. COMPACT BINARY PROGENITORS OF SHORT GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Giacomazzo, Bruno [JILA, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309 (United States); Perna, Rosalba [JILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States); Rezzolla, Luciano [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Potsdam D-14476 (Germany); Troja, Eleonora [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Lazzati, Davide [Department of Physics, NC State University, 2401 Stinson Drive, Raleigh, NC 27695-8202 (United States)

    2013-01-10

    In recent years, detailed observations and accurate numerical simulations have provided support to the idea that mergers of compact binaries containing either two neutron stars (NSs) or an NS and a black hole (BH) may constitute the central engine of short gamma-ray bursts (SGRBs). The merger of such compact binaries is expected to lead to the production of a spinning BH surrounded by an accreting torus. Several mechanisms can extract energy from this system and power the SGRBs. Here we connect observations and numerical simulations of compact binary mergers, and use the current sample of SGRBs with measured energies to constrain the mass of their powering tori. By comparing the masses of the tori with the results of fully general-relativistic simulations, we are able to infer the properties of the binary progenitors that yield SGRBs. By assuming a constant efficiency in converting torus mass into jet energy, {epsilon}{sub jet} = 10%, we find that most of the tori have masses smaller than 0.01 M{sub Sun }, favoring 'high-mass' binary NSs mergers, i.e., binaries with total masses {approx}> 1.5 the maximum mass of an isolated NS. This has important consequences for the gravitational wave signals that may be detected in association with SGRBs, since 'high-mass' systems do not form a long-lived hypermassive NS after the merger. While NS-BH systems cannot be excluded to be the engine of at least some of the SGRBs, the BH would need to have an initial spin of {approx}0.9 or higher.

  8. Microscopic analysis of irradiated AGR-1 coated particle fuel compacts

    SciTech Connect (OSTI)

    Scott Ploger; Paul Demkowicz; John Hunn; Robert Morris

    2012-10-01

    The AGR-1 experiment involved irradiation of 72 TRISO-coated particle fuel compacts to a peak burnup of 19.5% FIMA with no in-pile failures observed out of 3×105 total particles. Irradiated AGR-1 fuel compacts have been cross-sectioned and analyzed with optical microscopy to characterize kernel, buffer, and coating behavior. Five compacts have been examined so far, 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 between approximately 40-80 individual particles 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, over 800 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 approximately 23% of the particles, and these fractures often resulted in unconstrained kernel swelling 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 three particles, all in conjunction with IPyC-SiC debonding. Compiled results suggest that the deliberate coating fabrication variations influenced the frequencies of IPyC fractures, IPyC-SiC debonds, and SiC fractures.

  9. Compact cyclone filter train for radiological and hazardous environments

    DOE Patents [OSTI]

    Bench, Thomas R. (Pittsburgh, PA)

    1998-01-01

    A compact cyclone filter train for the removal of hazardous and radiologi particles from a gaseous fluid medium which permits a small cyclone separator to be used in a very small space envelope due to the arrangement of the filter housing adjacent to the separator with the cyclone separator and the filters mounted on a plate. The entire unit will have a hoist connection at the center of gravity so that the entire unit including the separator, the filters, and the base can be lifted and repositioned as desired.

  10. Compact cyclone filter train for radiological and hazardous environments

    DOE Patents [OSTI]

    Bench, T.R.

    1998-04-28

    A compact cyclone filter train is disclosed for the removal of hazardous and radiological particles from a gaseous fluid medium. This filter train permits a small cyclone separator to be used in a very small space envelope due to the arrangement of the filter housing adjacent to the separator with the cyclone separator and the filters mounted on a plate. The entire unit will have a hoist connection at the center of gravity so that the entire unit including the separator, the filters, and the base can be lifted and repositioned as desired. 3 figs.

  11. Pink-Beam, Highly-Accurate Compact Water Cooled Slits

    SciTech Connect (OSTI)

    Lyndaker, Aaron; Deyhim, Alex; Jayne, Richard; Waterman, Dave; Caletka, Dave; Steadman, Paul; Dhesi, Sarnjeet

    2007-01-19

    Advanced Design Consulting, Inc. (ADC) has designed accurate compact slits for applications where high precision is required. The system consists of vertical and horizontal slit mechanisms, a vacuum vessel which houses them, water cooling lines with vacuum guards connected to the individual blades, stepper motors with linear encoders, limit (home position) switches and electrical connections including internal wiring for a drain current measurement system. The total slit size is adjustable from 0 to 15 mm both vertically and horizontally. Each of the four blades are individually controlled and motorized. In this paper, a summary of the design and Finite Element Analysis of the system are presented.

  12. Diffusion Welding of Compact Heat Exchangers for Nuclear Applications

    SciTech Connect (OSTI)

    Denis Clark; Ron Mizia; Dr. Michael V. Glazoff; Mr. Michael W. Patterson

    2012-06-01

    The next-­-generation nuclear plant (NGNP) is designed to be a flexible source of energy, producing various mixes of electrical energy and process heat (for example, for hydrogen generation) on demand. Compact heat exchangers provide an attractive way to move energy from the helium primary reactor coolant to process heat uses. For process heat efficiency, reactor outlet temperatures of 750-­-900°C are desirable. There are minor but deleterious components in the primary coolant; the number of alloys that can handle this environment is small. The present work concentrates on Alloys 800H and 617.

  13. Porous silicon ring resonator for compact, high sensitivity biosensing applications

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

    Rodriguez, Gilberto A.; Hu, Shuren; Weiss, Sharon M.

    2015-01-01

    A ring resonator is patterned on a porous silicon slab waveguide to produce a compact, high quality factor biosensor with a large internal surface area available for enhanced recognition of biological and chemical molecules. The porous nature of the ring resonator allows molecules to directly interact with the guided mode. Quality factors near 10,000 were measured for porous silicon ring resonators with a radius of 25 ?m. A bulk detection sensitivity of 380 nm/RIU was measured upon exposure to salt water solutions. Specific detection of nucleic acid molecules was demonstrated with a surface detection sensitivity of 4 pm/nM.

  14. Simulated and experimental compression of a compact toroid

    SciTech Connect (OSTI)

    Johnson, J N; Hwang, D Q; Horton, R D; Evans, R W; Owen, J M

    2009-05-06

    We present simulation results and experimental data for the compression of a compact toroid by a conducting nozzle without a center electrode. In both simulation and experiment, the flow of the plasma is greatly obstructed by even modest magnetic fields. A simple mechanism for this obstruction is suggested by our simulations. In particular, the configuration of the plasmoid's magnetic field plays a significant role in the success of the experiment. We analyze two types of plasma configurations under compression and demonstrate that the results from the simulations matches those from the experiments, and that the mechanism predicts the different behaviors observed in the two cases.

  15. A compact electron gun for time-resolved electron diffraction

    SciTech Connect (OSTI)

    Robinson, Matthew S.; Lane, Paul D.; Wann, Derek A.

    2015-01-15

    A novel compact time-resolved electron diffractometer has been built with the primary goal of studying the ultrafast molecular dynamics of photoexcited gas-phase molecules. Here, we discuss the design of the electron gun, which is triggered by a Ti:Sapphire laser, before detailing a series of calibration experiments relating to the electron-beam properties. As a further test of the apparatus, initial diffraction patterns have been collected for thin, polycrystalline platinum samples, which have been shown to match theoretical patterns. The data collected demonstrate the focusing effects of the magnetic lens on the electron beam, and how this relates to the spatial resolution of the diffraction pattern.

  16. Deficiency of Broad Line AGNs in Compact Groups of Galaxies

    E-Print Network [OSTI]

    M. A. Martinez; A. del Olmo; R. Coziol; P. Focardi

    2008-03-25

    Based on a new survey of AGN activity in Compact Groups of Galaxies, we report a remarkable deficiency of Broad Line AGNs as compared to Narrow Line AGNs. The cause of such deficiency could be related to the average low luminosity of AGNs in CGs: $10^{39}$ erg s$^{-1}$. This result may imply lower accretion rates in CG AGNs, making Broad Line Regions (BLR) undetectable, or may indicate a genuine absence of BLRs. Both phenomena are consistent with gas stripping through tidal interaction and dry mergers.

  17. A Compilation of Redshifts for Compact Groups of Galaxies

    E-Print Network [OSTI]

    G. C. Baiesi Pillastrini

    2007-03-21

    We present a compilation of redshifts for 4,911 Compact Groups of galaxies (CG) referenced to the heliocentric reference frame, where 694 of them are available from the literature as of 1992. An unpublished redshift list for 4,217 CGs identified in the SDSS data release 4 by Deng et al. (2006) has been added too. We present an additional list of 157 CGs with published redshifts for one or more member galaxies and 13 apparent CGs with discrepant memberships. The electronic version of the compilation is provided by email request.

  18. Simple and Compact Nozzle Design for Laser Vaporization Sources

    E-Print Network [OSTI]

    Kokish, M G; Odom, B C

    2015-01-01

    We have developed and implemented a compact transparent nozzle for use in laser vaporization sources. This nozzle eliminates the need for an ablation aperture, allowing for a more intense molecular beam. We use this nozzle to prepare a molecular beam of aluminum monohydride (AlH) suitable for ion trap loading of AlH$^+$ via photoionization in ultra-high vacuum. We demonstrate stable AlH production over hour time scales using a liquid ablation target. The long-term stability, low heat load and fast ion production rate of this source are well-suited to molecular ion experiments employing destructive state readout schemes requiring frequent trap reloading.

  19. Compact objects from gravitational collapse: an analytical toy model

    E-Print Network [OSTI]

    Joshi, Pankaj S

    2015-01-01

    We develop here a procedure to obtain regular static configurations as resulting from dynamical gravitational collapse of a massive matter cloud in general relativity. Under certain general physical assumptions for the collapsing cloud, we find the class of dynamical models that lead to an equilibrium configuration. To illustrate this, we provide a class of perfect fluid collapse models that lead to a static constant density object as limit. We suggest that similar models might possibly constitute the basis for the description of formation of compact objects in nature.

  20. A compact neutron generator using a field ionization source

    SciTech Connect (OSTI)

    Persaud, Arun; Waldmann, Ole; Kapadia, Rehan; Takei, Kuniharu; Javey, Ali; Schenkel, Thomas

    2011-10-31

    Field ionization as a means to create ions for compact and rugged neutron sources is pursued. Arrays of carbon nano-#12;bers promise the high #12;eld-enhancement factors required for efficient field ionization. We report on the fabrication of arrays of #12;field emitters with a density up to 10{sup 6} tips/cm{sup 2} and measure their performance characteristics using electron field emission. The critical issue of uniformity is discussed, as are efforts towards coating the nano-fibers to enhance their lifetime and surface properties.