Sample records for massively parallel microcell-based

  1. Unsteady Turbomachinery Computations Using Massively Parallel Platforms

    E-Print Network [OSTI]

    Alonso, Juan J.

    Unsteady Turbomachinery Computations Using Massively Parallel Platforms Edwin van der Weide with the inherently unsteady nature of turbomachinery flows, due to the motion of the rotors, this means

  2. Massively Parallel Data Mining Using Reconfigurable Hardware

    E-Print Network [OSTI]

    Chamberlain, Roger

    ]. The basic idea is to decompose the data mining oper- ation into two components. The low-level componentMassively Parallel Data Mining Using Reconfigurable Hardware: Approximate String Matching Qiong. Chamberlain, Ronald S. Indeck, Benjamin West, and Jason White, "Massively Parallel Data Mining Using

  3. VALIDATION OF MASSIVELY PARALLEL SIMULATIONS OF DYNAMIC FRACTURE AND

    E-Print Network [OSTI]

    Barr, Al

    VALIDATION OF MASSIVELY PARALLEL SIMULATIONS OF DYNAMIC FRACTURE AND FRAGMENTATION OF BRITTLE element simulations of dynamic fracture and fragmentation of brittle solids are presented. Fracture the results of massively parallel numerical simulations of dynamic fracture and fragmentation in brittle

  4. MASSIVE HYBRID PARALLELISM FOR FULLY IMPLICIT MULTIPHYSICS

    SciTech Connect (OSTI)

    Cody J. Permann; David Andrs; John W. Peterson; Derek R. Gaston

    2013-05-01T23:59:59.000Z

    As hardware advances continue to modify the supercomputing landscape, traditional scientific software development practices will become more outdated, ineffective, and inefficient. The process of rewriting/retooling existing software for new architectures is a Sisyphean task, and results in substantial hours of development time, effort, and money. Software libraries which provide an abstraction of the resources provided by such architectures are therefore essential if the computational engineering and science communities are to continue to flourish in this modern computing environment. The Multiphysics Object Oriented Simulation Environment (MOOSE) framework enables complex multiphysics analysis tools to be built rapidly by scientists, engineers, and domain specialists, while also allowing them to both take advantage of current HPC architectures, and efficiently prepare for future supercomputer designs. MOOSE employs a hybrid shared-memory and distributed-memory parallel model and provides a complete and consistent interface for creating multiphysics analysis tools. In this paper, a brief discussion of the mathematical algorithms underlying the framework and the internal object-oriented hybrid parallel design are given. Representative massively parallel results from several applications areas are presented, and a brief discussion of future areas of research for the framework are provided.

  5. Massive hybrid parallelism for fully implicit multiphysics

    SciTech Connect (OSTI)

    Gaston, D. R.; Permann, C. J.; Andrs, D.; Peterson, J. W. [Idaho National Laboratory, 2525 N. Fremont Ave., Idaho Falls, ID 83415 (United States)

    2013-07-01T23:59:59.000Z

    As hardware advances continue to modify the supercomputing landscape, traditional scientific software development practices will become more outdated, ineffective, and inefficient. The process of rewriting/retooling existing software for new architectures is a Sisyphean task, and results in substantial hours of development time, effort, and money. Software libraries which provide an abstraction of the resources provided by such architectures are therefore essential if the computational engineering and science communities are to continue to flourish in this modern computing environment. The Multiphysics Object Oriented Simulation Environment (MOOSE) framework enables complex multiphysics analysis tools to be built rapidly by scientists, engineers, and domain specialists, while also allowing them to both take advantage of current HPC architectures, and efficiently prepare for future supercomputer designs. MOOSE employs a hybrid shared-memory and distributed-memory parallel model and provides a complete and consistent interface for creating multiphysics analysis tools. In this paper, a brief discussion of the mathematical algorithms underlying the framework and the internal object-oriented hybrid parallel design are given. Representative massively parallel results from several applications areas are presented, and a brief discussion of future areas of research for the framework are provided. (authors)

  6. Massively Parallel Indirect Dielectrophoresis Controlled Placement of Carbon Nanotubes.

    E-Print Network [OSTI]

    Conley, Hiram Jacob

    2009-01-01T23:59:59.000Z

    ??Placement of single walled carbon nanotubes is demonstrated through massively parallel indirect dielectrophoresis (MPID). MPID is shown to be able to control the placement of… (more)

  7. Nuclear shell-model code for massive parallel computation, "KSHELL"

    E-Print Network [OSTI]

    Noritaka Shimizu

    2013-10-21T23:59:59.000Z

    A new code for nuclear shell-model calculations, "KSHELL", is developed. It aims at carrying out both massively parallel computation and single-node computation in the same manner. We solve the Schr\\"{o}dinger's equation in the $M$-scheme shell-model model space, utilizing Thick-Restart Lanczos method. During the Lanczos iteration, the whole Hamiltonian matrix elements are generated "on-the-fly" in every matrix-vector multiplication. The vectors of the Lanczos method are distributed and stored on memory of each parallel node. We report that the newly developed code has high parallel efficiency on FX10 supercomputer and a PC with multi-cores.

  8. Routing performance analysis and optimization within a massively parallel computer

    DOE Patents [OSTI]

    Archer, Charles Jens; Peters, Amanda; Pinnow, Kurt Walter; Swartz, Brent Allen

    2013-04-16T23:59:59.000Z

    An apparatus, program product and method optimize the operation of a massively parallel computer system by, in part, receiving actual performance data concerning an application executed by the plurality of interconnected nodes, and analyzing the actual performance data to identify an actual performance pattern. A desired performance pattern may be determined for the application, and an algorithm may be selected from among a plurality of algorithms stored within a memory, the algorithm being configured to achieve the desired performance pattern based on the actual performance data.

  9. Massively Parallel Interrogation of Aptamer Sequence, Structure and Function

    SciTech Connect (OSTI)

    Fischer, N O; Tok, J B; Tarasow, T M

    2008-02-08T23:59:59.000Z

    Optimization of high affinity reagents is a significant bottleneck in medicine and the life sciences. The ability to synthetically create thousands of permutations of a lead high-affinity reagent and survey the properties of individual permutations in parallel could potentially relieve this bottleneck. Aptamers are single stranded oligonucleotides affinity reagents isolated by in vitro selection processes and as a class have been shown to bind a wide variety of target molecules. Methodology/Principal Findings. High density DNA microarray technology was used to synthesize, in situ, arrays of approximately 3,900 aptamer sequence permutations in triplicate. These sequences were interrogated on-chip for their ability to bind the fluorescently-labeled cognate target, immunoglobulin E, resulting in the parallel execution of thousands of experiments. Fluorescence intensity at each array feature was well resolved and shown to be a function of the sequence present. The data demonstrated high intra- and interchip correlation between the same features as well as among the sequence triplicates within a single array. Consistent with aptamer mediated IgE binding, fluorescence intensity correlated strongly with specific aptamer sequences and the concentration of IgE applied to the array. The massively parallel sequence-function analyses provided by this approach confirmed the importance of a consensus sequence found in all 21 of the original IgE aptamer sequences and support a common stem:loop structure as being the secondary structure underlying IgE binding. The microarray application, data and results presented illustrate an efficient, high information content approach to optimizing aptamer function. It also provides a foundation from which to better understand and manipulate this important class of high affinity biomolecules.

  10. Massively parallel processor networks with optical express channels

    DOE Patents [OSTI]

    Deri, Robert J. (Pleasanton, CA); Brooks, III, Eugene D. (Livermore, CA); Haigh, Ronald E. (Tracy, CA); DeGroot, Anthony J. (Castro Valley, CA)

    1999-01-01T23:59:59.000Z

    An optical method for separating and routing local and express channel data comprises interconnecting the nodes in a network with fiber optic cables. A single fiber optic cable carries both express channel traffic and local channel traffic, e.g., in a massively parallel processor (MPP) network. Express channel traffic is placed on, or filtered from, the fiber optic cable at a light frequency or a color different from that of the local channel traffic. The express channel traffic is thus placed on a light carrier that skips over the local intermediate nodes one-by-one by reflecting off of selective mirrors placed at each local node. The local-channel-traffic light carriers pass through the selective mirrors and are not reflected. A single fiber optic cable can thus be threaded throughout a three-dimensional matrix of nodes with the x,y,z directions of propagation encoded by the color of the respective light carriers for both local and express channel traffic. Thus frequency division multiple access is used to hierarchically separate the local and express channels to eliminate the bucket brigade latencies that would otherwise result if the express traffic had to hop between every local node to reach its ultimate destination.

  11. Massively parallel processor networks with optical express channels

    DOE Patents [OSTI]

    Deri, R.J.; Brooks, E.D. III; Haigh, R.E.; DeGroot, A.J.

    1999-08-24T23:59:59.000Z

    An optical method for separating and routing local and express channel data comprises interconnecting the nodes in a network with fiber optic cables. A single fiber optic cable carries both express channel traffic and local channel traffic, e.g., in a massively parallel processor (MPP) network. Express channel traffic is placed on, or filtered from, the fiber optic cable at a light frequency or a color different from that of the local channel traffic. The express channel traffic is thus placed on a light carrier that skips over the local intermediate nodes one-by-one by reflecting off of selective mirrors placed at each local node. The local-channel-traffic light carriers pass through the selective mirrors and are not reflected. A single fiber optic cable can thus be threaded throughout a three-dimensional matrix of nodes with the x,y,z directions of propagation encoded by the color of the respective light carriers for both local and express channel traffic. Thus frequency division multiple access is used to hierarchically separate the local and express channels to eliminate the bucket brigade latencies that would otherwise result if the express traffic had to hop between every local node to reach its ultimate destination. 3 figs.

  12. Massively parallel computational fluid dynamics calculations for aerodynamics and aerothermodynamics applications

    SciTech Connect (OSTI)

    Payne, J.L.; Hassan, B.

    1998-09-01T23:59:59.000Z

    Massively parallel computers have enabled the analyst to solve complicated flow fields (turbulent, chemically reacting) that were previously intractable. Calculations are presented using a massively parallel CFD code called SACCARA (Sandia Advanced Code for Compressible Aerothermodynamics Research and Analysis) currently under development at Sandia National Laboratories as part of the Department of Energy (DOE) Accelerated Strategic Computing Initiative (ASCI). Computations were made on a generic reentry vehicle in a hypersonic flowfield utilizing three different distributed parallel computers to assess the parallel efficiency of the code with increasing numbers of processors. The parallel efficiencies for the SACCARA code will be presented for cases using 1, 150, 100 and 500 processors. Computations were also made on a subsonic/transonic vehicle using both 236 and 521 processors on a grid containing approximately 14.7 million grid points. Ongoing and future plans to implement a parallel overset grid capability and couple SACCARA with other mechanics codes in a massively parallel environment are discussed.

  13. High-quality draft assemblies of mammalian genomes from massively parallel sequence data

    E-Print Network [OSTI]

    Gnerre, Sante

    Massively parallel DNA sequencing technologies are revolutionizing genomics by making it possible to generate billions of relatively short (~100-base) sequence reads at very low cost. Whereas such data can be readily used ...

  14. Scalable Parallel Algorithms for Massive Scale-free Graphs

    E-Print Network [OSTI]

    Pearce, Roger Allan

    2013-12-05T23:59:59.000Z

    Efficiently storing and processing massive graph data sets is a challenging problem as researchers seek to leverage “Big Data” to answer next-generation scientific questions. New techniques are required to process large scale-free graphs in shared...

  15. Massively parallel DNA sequencing: the new frontier in biogeography

    E-Print Network [OSTI]

    Rocha, Luiz A.; Bernal, Moisés A.; Gaither, Michelle R.; Alfaro, Michael E.

    2013-01-01T23:59:59.000Z

    2007) Popula? tion  genomics:  whole?genome  analysis  of evolutionary scales.  BMC  Genomics, 13, 403.   Bickford, 2012)  Population  genomics  of  parallel  adaptation  in 

  16. Experiences with global optimization techniques in massively parallel processing environments

    SciTech Connect (OSTI)

    Hall, J.H.; Hiromoto, R.

    1988-01-01T23:59:59.000Z

    The modeling of many physically relevant processes involves the location of global extrema, which are often surrounded by numerous local extrema. The effort involved in locating these extrema grows rapidly with increasing dimensionality of the problems being investigated. A method of analysis for algorithms from the perspective of a parallel processing environment is developed and applied to the family of Monte Carlo global optimization schemes. A new highly parallel Monte Carlo algorithm is presented. Chaotic iteration schemes resulting in nondeterministic algorithms are discussed, and an analysis of the optimal conditions for their application to this class of problems is presented. 11 refs., 4 figs.

  17. Massively-Parallel Direct Numerical Simulation of Gas Turbine Endwall Film-Cooling Conjugate Heat Transfer

    E-Print Network [OSTI]

    Meador, Charles Michael

    2011-02-22T23:59:59.000Z

    MASSIVELY-PARALLEL DIRECT NUMERICAL SIMULATION OF GAS TURBINE ENDWALL FILM-COOLING CONJUGATE HEAT TRANSFER A Thesis by CHARLES MICHAEL MEADOR Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment of the requirements... for the degree of MASTER OF SCIENCE December 2010 Major Subject: Mechanical Engineering MASSIVELY-PARALLEL DIRECT NUMERICAL SIMULATION OF GAS TURBINE ENDWALL FILM-COOLING CONJUGATE HEAT TRANSFER A Thesis by CHARLES MICHAEL MEADOR Submitted to the O ce of Graduate...

  18. Massive Data-Parallel Swarm Simulation and Visualisation using CUDA

    E-Print Network [OSTI]

    Hinze, Thomas

    for the project was to employ CUDA for simulating natural movement and behaviour of a fish swarm. As a fish swarm by calculating the state of a fish at time ti+1 as a function of the state of the whole swarm at time ti. Since this function is equal for all fishes, the state of the whole swarm can easily be calculated in parallel

  19. Massively parallel X-ray holography STEFANO MARCHESINI1,2

    E-Print Network [OSTI]

    Petta, Jason

    , and a bacterial cell with a soft-X-ray free-electron laser, where illumination by a single 15-fs pulse was successfully used in producing the holographic image. As X-ray lasers move to shorter wavelengths we expectMassively parallel X-ray holography STEFANO MARCHESINI1,2 *, SE´BASTIEN BOUTET3,4 , ANNE E

  20. Self-Assembly Techniques for Massively Parallel Packaging of MEMS Devices

    E-Print Network [OSTI]

    Self-Assembly Techniques for Massively Parallel Packaging of MEMS Devices Jiandong Fang-1346, or to the author. Signature Date July 31, 2006 #12;#12;University of Washington Abstract Self-Assembly Techniques. B¨ohringer Electrical Engineering This dissertation investigates applications of self-assembly

  1. Massively Parallel Computation of Sti Propagating Combustion frontsMarc Garbey and Damien Tromeur-Dervout

    E-Print Network [OSTI]

    Garbey, Marc

    In this paper we study the computation of combustion fronts using MIMD archi- tecture. Our applications in gas models of combustion fronts: rst, a classical thermo-di usive model describing the combustion of a gasMassively Parallel Computation of Sti Propagating Combustion frontsMarc Garbey and Damien Tromeur

  2. Analysis of gallium arsenide deposition in a horizontal chemical vapor deposition reactor using massively parallel computations

    SciTech Connect (OSTI)

    Salinger, A.G.; Shadid, J.N.; Hutchinson, S.A. [and others

    1998-01-01T23:59:59.000Z

    A numerical analysis of the deposition of gallium from trimethylgallium (TMG) and arsine in a horizontal CVD reactor with tilted susceptor and a three inch diameter rotating substrate is performed. The three-dimensional model includes complete coupling between fluid mechanics, heat transfer, and species transport, and is solved using an unstructured finite element discretization on a massively parallel computer. The effects of three operating parameters (the disk rotation rate, inlet TMG fraction, and inlet velocity) and two design parameters (the tilt angle of the reactor base and the reactor width) on the growth rate and uniformity are presented. The nonlinear dependence of the growth rate uniformity on the key operating parameters is discussed in detail. Efficient and robust algorithms for massively parallel reacting flow simulations, as incorporated into our analysis code MPSalsa, make detailed analysis of this complicated system feasible.

  3. Massively-parallel Spectral Element Algorithm Development for High Speed Flows

    E-Print Network [OSTI]

    Camp, Joshua Lane

    2013-10-07T23:59:59.000Z

    Fluid Dynamics in the Design Cycle . . . . . . . . . . 3 1.2.1 Nature of the Flow Equations and Turbulence . . . . . . . . . 3 1.2.2 Industrial CFD Use . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2.3 Massive-parallelism and CFD... . . . . . . . . . . . . . . . . . . 7 1.2.4 Towards Improving Design Cycle Analysis . . . . . . . . . . . 7 1.3 Keys for Effective High-Fidelity CFD . . . . . . . . . . . . . . . . . . 9 1.3.1 Need for High Order . . . . . . . . . . . . . . . . . . . . . . . 9 1.3.2 Need for High...

  4. Massively parallel Monte Carlo for many-particle simulations on GPUs

    SciTech Connect (OSTI)

    Anderson, Joshua A.; Jankowski, Eric [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)] [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Grubb, Thomas L. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Engel, Michael [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)] [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Glotzer, Sharon C., E-mail: sglotzer@umich.edu [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)

    2013-12-01T23:59:59.000Z

    Current trends in parallel processors call for the design of efficient massively parallel algorithms for scientific computing. Parallel algorithms for Monte Carlo simulations of thermodynamic ensembles of particles have received little attention because of the inherent serial nature of the statistical sampling. In this paper, we present a massively parallel method that obeys detailed balance and implement it for a system of hard disks on the GPU. We reproduce results of serial high-precision Monte Carlo runs to verify the method. This is a good test case because the hard disk equation of state over the range where the liquid transforms into the solid is particularly sensitive to small deviations away from the balance conditions. On a Tesla K20, our GPU implementation executes over one billion trial moves per second, which is 148 times faster than on a single Intel Xeon E5540 CPU core, enables 27 times better performance per dollar, and cuts energy usage by a factor of 13. With this improved performance we are able to calculate the equation of state for systems of up to one million hard disks. These large system sizes are required in order to probe the nature of the melting transition, which has been debated for the last forty years. In this paper we present the details of our computational method, and discuss the thermodynamics of hard disks separately in a companion paper.

  5. Molecular Dynamics Simulations from SNL's Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS)

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

    Plimpton, Steve; Thompson, Aidan; Crozier, Paul

    LAMMPS (http://lammps.sandia.gov/index.html) stands for Large-scale Atomic/Molecular Massively Parallel Simulator and is a code that can be used to model atoms or, as the LAMMPS website says, as a parallel particle simulator at the atomic, meso, or continuum scale. This Sandia-based website provides a long list of animations from large simulations. These were created using different visualization packages to read LAMMPS output, and each one provides the name of the PI and a brief description of the work done or visualization package used. See also the static images produced from simulations at http://lammps.sandia.gov/pictures.html The foundation paper for LAMMPS is: S. Plimpton, Fast Parallel Algorithms for Short-Range Molecular Dynamics, J Comp Phys, 117, 1-19 (1995), but the website also lists other papers describing contributions to LAMMPS over the years.

  6. MADmap: A Massively Parallel Maximum-Likelihood Cosmic Microwave Background Map-Maker

    SciTech Connect (OSTI)

    Cantalupo, Christopher; Borrill, Julian; Jaffe, Andrew; Kisner, Theodore; Stompor, Radoslaw

    2009-06-09T23:59:59.000Z

    MADmap is a software application used to produce maximum-likelihood images of the sky from time-ordered data which include correlated noise, such as those gathered by Cosmic Microwave Background (CMB) experiments. It works efficiently on platforms ranging from small workstations to the most massively parallel supercomputers. Map-making is a critical step in the analysis of all CMB data sets, and the maximum-likelihood approach is the most accurate and widely applicable algorithm; however, it is a computationally challenging task. This challenge will only increase with the next generation of ground-based, balloon-borne and satellite CMB polarization experiments. The faintness of the B-mode signal that these experiments seek to measure requires them to gather enormous data sets. MADmap is already being run on up to O(1011) time samples, O(108) pixels and O(104) cores, with ongoing work to scale to the next generation of data sets and supercomputers. We describe MADmap's algorithm based around a preconditioned conjugate gradient solver, fast Fourier transforms and sparse matrix operations. We highlight MADmap's ability to address problems typically encountered in the analysis of realistic CMB data sets and describe its application to simulations of the Planck and EBEX experiments. The massively parallel and distributed implementation is detailed and scaling complexities are given for the resources required. MADmap is capable of analysing the largest data sets now being collected on computing resources currently available, and we argue that, given Moore's Law, MADmap will be capable of reducing the most massive projected data sets.

  7. User's Guide for TOUGH2-MP - A Massively Parallel Version of the TOUGH2 Code

    SciTech Connect (OSTI)

    Earth Sciences Division; Zhang, Keni; Zhang, Keni; Wu, Yu-Shu; Pruess, Karsten

    2008-05-27T23:59:59.000Z

    TOUGH2-MP is a massively parallel (MP) version of the TOUGH2 code, designed for computationally efficient parallel simulation of isothermal and nonisothermal flows of multicomponent, multiphase fluids in one, two, and three-dimensional porous and fractured media. In recent years, computational requirements have become increasingly intensive in large or highly nonlinear problems for applications in areas such as radioactive waste disposal, CO2 geological sequestration, environmental assessment and remediation, reservoir engineering, and groundwater hydrology. The primary objective of developing the parallel-simulation capability is to significantly improve the computational performance of the TOUGH2 family of codes. The particular goal for the parallel simulator is to achieve orders-of-magnitude improvement in computational time for models with ever-increasing complexity. TOUGH2-MP is designed to perform parallel simulation on multi-CPU computational platforms. An earlier version of TOUGH2-MP (V1.0) was based on the TOUGH2 Version 1.4 with EOS3, EOS9, and T2R3D modules, a software previously qualified for applications in the Yucca Mountain project, and was designed for execution on CRAY T3E and IBM SP supercomputers. The current version of TOUGH2-MP (V2.0) includes all fluid property modules of the standard version TOUGH2 V2.0. It provides computationally efficient capabilities using supercomputers, Linux clusters, or multi-core PCs, and also offers many user-friendly features. The parallel simulator inherits all process capabilities from V2.0 together with additional capabilities for handling fractured media from V1.4. This report provides a quick starting guide on how to set up and run the TOUGH2-MP program for users with a basic knowledge of running the (standard) version TOUGH2 code, The report also gives a brief technical description of the code, including a discussion of parallel methodology, code structure, as well as mathematical and numerical methods used. To familiarize users with the parallel code, illustrative sample problems are presented.

  8. Climate system modeling on massively parallel systems: LDRD Project 95-ERP-47 final report

    SciTech Connect (OSTI)

    Mirin, A.A.; Dannevik, W.P.; Chan, B.; Duffy, P.B.; Eltgroth, P.G.; Wehner, M.F.

    1996-12-01T23:59:59.000Z

    Global warming, acid rain, ozone depletion, and biodiversity loss are some of the major climate-related issues presently being addressed by climate and environmental scientists. Because unexpected changes in the climate could have significant effect on our economy, it is vitally important to improve the scientific basis for understanding and predicting the earth`s climate. The impracticality of modeling the earth experimentally in the laboratory together with the fact that the model equations are highly nonlinear has created a unique and vital role for computer-based climate experiments. However, today`s computer models, when run at desired spatial and temporal resolution and physical complexity, severely overtax the capabilities of our most powerful computers. Parallel processing offers significant potential for attaining increased performance and making tractable simulations that cannot be performed today. The principal goals of this project have been to develop and demonstrate the capability to perform large-scale climate simulations on high-performance computing systems (using methodology that scales to the systems of tomorrow), and to carry out leading-edge scientific calculations using parallelized models. The demonstration platform for these studies has been the 256-processor Cray-T3D located at Lawrence Livermore National Laboratory. Our plan was to undertake an ambitious program in optimization, proof-of-principle and scientific study. These goals have been met. We are now regularly using massively parallel processors for scientific study of the ocean and atmosphere, and preliminary parallel coupled ocean/atmosphere calculations are being carried out as well. Furthermore, our work suggests that it should be possible to develop an advanced comprehensive climate system model with performance scalable to the teraflops range. 9 refs., 3 figs.

  9. 3-D readout-electronics packaging for high-bandwidth massively paralleled imager

    DOE Patents [OSTI]

    Kwiatkowski, Kris (Los Alamos, NM); Lyke, James (Albuquerque, NM)

    2007-12-18T23:59:59.000Z

    Dense, massively parallel signal processing electronics are co-packaged behind associated sensor pixels. Microchips containing a linear or bilinear arrangement of photo-sensors, together with associated complex electronics, are integrated into a simple 3-D structure (a "mirror cube"). An array of photo-sensitive cells are disposed on a stacked CMOS chip's surface at a 45.degree. angle from light reflecting mirror surfaces formed on a neighboring CMOS chip surface. Image processing electronics are held within the stacked CMOS chip layers. Electrical connections couple each of said stacked CMOS chip layers and a distribution grid, the connections for distributing power and signals to components associated with each stacked CSMO chip layer.

  10. Massively parallel computation of 3D flow and reactions in chemical vapor deposition reactors

    SciTech Connect (OSTI)

    Salinger, A.G.; Shadid, J.N.; Hutchinson, S.A.; Hennigan, G.L.; Devine, K.D.; Moffat, H.K.

    1997-12-01T23:59:59.000Z

    Computer modeling of Chemical Vapor Deposition (CVD) reactors can greatly aid in the understanding, design, and optimization of these complex systems. Modeling is particularly attractive in these systems since the costs of experimentally evaluating many design alternatives can be prohibitively expensive, time consuming, and even dangerous, when working with toxic chemicals like Arsine (AsH{sub 3}): until now, predictive modeling has not been possible for most systems since the behavior is three-dimensional and governed by complex reaction mechanisms. In addition, CVD reactors often exhibit large thermal gradients, large changes in physical properties over regions of the domain, and significant thermal diffusion for gas mixtures with widely varying molecular weights. As a result, significant simplifications in the models have been made which erode the accuracy of the models` predictions. In this paper, the authors will demonstrate how the vast computational resources of massively parallel computers can be exploited to make possible the analysis of models that include coupled fluid flow and detailed chemistry in three-dimensional domains. For the most part, models have either simplified the reaction mechanisms and concentrated on the fluid flow, or have simplified the fluid flow and concentrated on rigorous reactions. An important CVD research thrust has been in detailed modeling of fluid flow and heat transfer in the reactor vessel, treating transport and reaction of chemical species either very simply or as a totally decoupled problem. Using the analogy between heat transfer and mass transfer, and the fact that deposition is often diffusion limited, much can be learned from these calculations; however, the effects of thermal diffusion, the change in physical properties with composition, and the incorporation of surface reaction mechanisms are not included in this model, nor can transitions to three-dimensional flows be detected.

  11. Three-dimensional electromagnetic modeling and inversion on massively parallel computers

    SciTech Connect (OSTI)

    Newman, G.A.; Alumbaugh, D.L. [Sandia National Labs., Albuquerque, NM (United States). Geophysics Dept.

    1996-03-01T23:59:59.000Z

    This report has demonstrated techniques that can be used to construct solutions to the 3-D electromagnetic inverse problem using full wave equation modeling. To this point great progress has been made in developing an inverse solution using the method of conjugate gradients which employs a 3-D finite difference solver to construct model sensitivities and predicted data. The forward modeling code has been developed to incorporate absorbing boundary conditions for high frequency solutions (radar), as well as complex electrical properties, including electrical conductivity, dielectric permittivity and magnetic permeability. In addition both forward and inverse codes have been ported to a massively parallel computer architecture which allows for more realistic solutions that can be achieved with serial machines. While the inversion code has been demonstrated on field data collected at the Richmond field site, techniques for appraising the quality of the reconstructions still need to be developed. Here it is suggested that rather than employing direct matrix inversion to construct the model covariance matrix which would be impossible because of the size of the problem, one can linearize about the 3-D model achieved in the inverse and use Monte-Carlo simulations to construct it. Using these appraisal and construction tools, it is now necessary to demonstrate 3-D inversion for a variety of EM data sets that span the frequency range from induction sounding to radar: below 100 kHz to 100 MHz. Appraised 3-D images of the earth`s electrical properties can provide researchers opportunities to infer the flow paths, flow rates and perhaps the chemistry of fluids in geologic mediums. It also offers a means to study the frequency dependence behavior of the properties in situ. This is of significant relevance to the Department of Energy, paramount to characterizing and monitoring of environmental waste sites and oil and gas exploration.

  12. System and method for representing and manipulating three-dimensional objects on massively parallel architectures

    DOE Patents [OSTI]

    Karasick, M.S.; Strip, D.R.

    1996-01-30T23:59:59.000Z

    A parallel computing system is described that comprises a plurality of uniquely labeled, parallel processors, each processor capable of modeling a three-dimensional object that includes a plurality of vertices, faces and edges. The system comprises a front-end processor for issuing a modeling command to the parallel processors, relating to a three-dimensional object. Each parallel processor, in response to the command and through the use of its own unique label, creates a directed-edge (d-edge) data structure that uniquely relates an edge of the three-dimensional object to one face of the object. Each d-edge data structure at least includes vertex descriptions of the edge and a description of the one face. As a result, each processor, in response to the modeling command, operates upon a small component of the model and generates results, in parallel with all other processors, without the need for processor-to-processor intercommunication. 8 figs.

  13. On the Kinematics of Solar Mirrors Using Massively Parallel Binary Actuation

    E-Print Network [OSTI]

    Dubowsky, Steven

    Precision mirrors are required for effective solar energy collectors. Manufacturing such mirrors and making them robust to disturbances such as thermal gradients is expensive. In this paper, the use of parallel binary ...

  14. A Novel Algorithm for Solving the Multidimensional Neutron Transport Equation on Massively Parallel Architectures

    SciTech Connect (OSTI)

    Azmy, Yousry

    2014-06-10T23:59:59.000Z

    We employ the Integral Transport Matrix Method (ITMM) as the kernel of new parallel solution methods for the discrete ordinates approximation of the within-group neutron transport equation. The ITMM abandons the repetitive mesh sweeps of the traditional source iterations (SI) scheme in favor of constructing stored operators that account for the direct coupling factors among all the cells' fluxes and between the cells' and boundary surfaces' fluxes. The main goals of this work are to develop the algorithms that construct these operators and employ them in the solution process, determine the most suitable way to parallelize the entire procedure, and evaluate the behavior and parallel performance of the developed methods with increasing number of processes, P. The fastest observed parallel solution method, Parallel Gauss-Seidel (PGS), was used in a weak scaling comparison with the PARTISN transport code, which uses the source iteration (SI) scheme parallelized with the Koch-baker-Alcouffe (KBA) method. Compared to the state-of-the-art SI-KBA with diffusion synthetic acceleration (DSA), this new method- even without acceleration/preconditioning-is completitive for optically thick problems as P is increased to the tens of thousands range. For the most optically thick cells tested, PGS reduced execution time by an approximate factor of three for problems with more than 130 million computational cells on P = 32,768. Moreover, the SI-DSA execution times's trend rises generally more steeply with increasing P than the PGS trend. Furthermore, the PGS method outperforms SI for the periodic heterogeneous layers (PHL) configuration problems. The PGS method outperforms SI and SI-DSA on as few as P = 16 for PHL problems and reduces execution time by a factor of ten or more for all problems considered with more than 2 million computational cells on P = 4.096.

  15. Space-charge-dominated beam dynamics simulations using the massively parallel processors (MPPs) of the Cray T3D

    SciTech Connect (OSTI)

    Liu, H.

    1996-10-01T23:59:59.000Z

    Computer simulations using the multi-particle code PARMELA with a three-dimensional point-by-point space charge algorithm have turned out to be very helpful in supporting injector commissioning and operations at Thomas Jefferson National Accelerator Facility (Jefferson Lab, formerly called CEBAF). However, this algorithm, which defines a typical N{sup 2} problem in CPU time scaling, is very time-consuming when N, the number of macro-particles, is large. Therefore, it is attractive to use massively parallel processors (MPPs) to speed up the simulations. Motivated by this, the authors modified the space charge subroutine for using the MPPs of the Cray T3D. The techniques used to parallelize and optimize the code on the T3D are discussed in this paper. The performance of the code on the T3D is examined in comparison with a Parallel Vector Processing supercomputer of the Cray C90 and an HP 735/15 high-end workstation.

  16. Distibuted Dense Numerical Linear Algebra Algorithms on massively parallel architectures: DPLASMA

    E-Print Network [OSTI]

    Luszczek, Piotr

    of communication and computation, task prioritization, architecture-aware scheduling and management of micro and execution in a distributed system. We demonstrate from our preliminary results that our DAG-based approach. Keywords: Linear systems, parallel algorithms, scheduling and task partitioning 1 Introduction

  17. Analysis and selection of optimal function implementations in massively parallel computer

    DOE Patents [OSTI]

    Archer, Charles Jens (Rochester, MN); Peters, Amanda (Rochester, MN); Ratterman, Joseph D. (Rochester, MN)

    2011-05-31T23:59:59.000Z

    An apparatus, program product and method optimize the operation of a parallel computer system by, in part, collecting performance data for a set of implementations of a function capable of being executed on the parallel computer system based upon the execution of the set of implementations under varying input parameters in a plurality of input dimensions. The collected performance data may be used to generate selection program code that is configured to call selected implementations of the function in response to a call to the function under varying input parameters. The collected performance data may be used to perform more detailed analysis to ascertain the comparative performance of the set of implementations of the function under the varying input parameters.

  18. A massively parallel method of characteristic neutral particle transport code for GPUs

    SciTech Connect (OSTI)

    Boyd, W. R.; Smith, K.; Forget, B. [Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)

    2013-07-01T23:59:59.000Z

    Over the past 20 years, parallel computing has enabled computers to grow ever larger and more powerful while scientific applications have advanced in sophistication and resolution. This trend is being challenged, however, as the power consumption for conventional parallel computing architectures has risen to unsustainable levels and memory limitations have come to dominate compute performance. Heterogeneous computing platforms, such as Graphics Processing Units (GPUs), are an increasingly popular paradigm for solving these issues. This paper explores the applicability of GPUs for deterministic neutron transport. A 2D method of characteristics (MOC) code - OpenMOC - has been developed with solvers for both shared memory multi-core platforms as well as GPUs. The multi-threading and memory locality methodologies for the GPU solver are presented. Performance results for the 2D C5G7 benchmark demonstrate 25-35 x speedup for MOC on the GPU. The lessons learned from this case study will provide the basis for further exploration of MOC on GPUs as well as design decisions for hardware vendors exploring technologies for the next generation of machines for scientific computing. (authors)

  19. Massively parallel neural computation

    E-Print Network [OSTI]

    Fox, Paul James

    2013-03-12T23:59:59.000Z

    of their configurable blocks to be altered using programmable floating gate transistors. The biggest weakness of analogue neurons models is their lack of scalability, for example Indiveri et al. (2006) implement 32 neurons on a chip, while Saighi et al. (2005) implement... 5 and Basu et al. up to 84 integrate and fire neurons or a smaller number of Hodgkin-Huxley neurons. CHAPTER 2. BACKGROUND 33 Analogue components have large physical size compared to the transistors used in digital systems, and hence the number...

  20. Parallelization

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 - September 2006 TheSteven Ashby Dr.presentations Papers &ParadeParallel

  1. Massively-parallel electron dynamics calculations in real-time and real-space: Toward applications to nanostructures of more than ten-nanometers in size

    SciTech Connect (OSTI)

    Noda, Masashi; Ishimura, Kazuya; Nobusada, Katsuyuki [Institute for Molecular Science, Myodaiji, Okazaki, Aichi 444-8585 (Japan); Yabana, Kazuhiro; Boku, Taisuke [Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan)

    2014-05-15T23:59:59.000Z

    A highly efficient program of massively parallel calculations for electron dynamics has been developed in an effort to apply the method to optical response of nanostructures of more than ten-nanometers in size. The approach is based on time-dependent density functional theory calculations in real-time and real-space. The computational code is implemented by using simple algorithms with a finite-difference method in space derivative and Taylor expansion in time-propagation. Since the computational program is free from the algorithms of eigenvalue problems and fast-Fourier-transformation, which are usually implemented in conventional quantum chemistry or band structure calculations, it is highly suitable for massively parallel calculations. Benchmark calculations using the K computer at RIKEN demonstrate that the parallel efficiency of the program is very high on more than 60?000 CPU cores. The method is applied to optical response of arrays of C{sub 60} orderly nanostructures of more than 10 nm in size. The computed absorption spectrum is in good agreement with the experimental observation.

  2. Method and apparatus for routing data in an inter-nodal communications lattice of a massively parallel computer system by routing through transporter nodes

    DOE Patents [OSTI]

    Archer, Charles Jens (Rochester, MN); Musselman, Roy Glenn (Rochester, MN); Peters, Amanda (Rochester, MN); Pinnow, Kurt Walter (Rochester, MN); Swartz, Brent Allen (Chippewa Falls, WI); Wallenfelt, Brian Paul (Eden Prairie, MN)

    2010-11-16T23:59:59.000Z

    A massively parallel computer system contains an inter-nodal communications network of node-to-node links. An automated routing strategy routes packets through one or more intermediate nodes of the network to reach a destination. Some packets are constrained to be routed through respective designated transporter nodes, the automated routing strategy determining a path from a respective source node to a respective transporter node, and from a respective transporter node to a respective destination node. Preferably, the source node chooses a routing policy from among multiple possible choices, and that policy is followed by all intermediate nodes. The use of transporter nodes allows greater flexibility in routing.

  3. Significant Association between Sulfate-Reducing Bacteria and Uranium-Reducing Microbial Communities as Revealed by a Combined Massively Parallel Sequencing-Indicator Species Approach

    SciTech Connect (OSTI)

    Cardenas, Erick [Michigan State University, East Lansing; Leigh, Mary Beth [Michigan State University, East Lansing; Marsh, Terence [Michigan State University, East Lansing; Tiedje, James M. [Michigan State University, East Lansing; Wu, Wei-min [Stanford University; Luo, Jian [Stanford University; Ginder-Vogel, Matthew [Stanford University; Kitanidis, Peter K. [Stanford University; Criddle, Craig [Stanford University; Carley, Jack M [ORNL; Carroll, Sue L [ORNL; Gentry, Terry J [ORNL; Watson, David B [ORNL; Gu, Baohua [ORNL; Jardine, Philip M [ORNL; Zhou, Jizhong [ORNL

    2010-10-01T23:59:59.000Z

    Massively parallel sequencing has provided a more affordable and high-throughput method to study microbial communities, although it has mostly been used in an exploratory fashion. We combined pyrosequencing with a strict indicator species statistical analysis to test if bacteria specifically responded to ethanol injection that successfully promoted dissimilatory uranium(VI) reduction in the subsurface of a uranium contamination plume at the Oak Ridge Field Research Center in Tennessee. Remediation was achieved with a hydraulic flow control consisting of an inner loop, where ethanol was injected, and an outer loop for flow-field protection. This strategy reduced uranium concentrations in groundwater to levels below 0.126 M and created geochemical gradients in electron donors from the inner-loop injection well toward the outer loop and downgradient flow path. Our analysis with 15 sediment samples from the entire test area found significant indicator species that showed a high degree of adaptation to the three different hydrochemical-created conditions. Castellaniella and Rhodanobacter characterized areas with low pH, heavy metals, and low bioactivity, while sulfate-, Fe(III)-, and U(VI)-reducing bacteria (Desulfovibrio, Anaeromyxobacter, and Desulfosporosinus) were indicators of areas where U(VI) reduction occurred. The abundance of these bacteria, as well as the Fe(III) and U(VI) reducer Geobacter, correlated with the hydraulic connectivity to the substrate injection site, suggesting that the selected populations were a direct response to electron donor addition by the groundwater flow path. A false-discovery-rate approach was implemented to discard false-positive results by chance, given the large amount of data compared.

  4. A combined massively parallel sequencing indicator species approach revealed significant association between sulfate-reducing bacteria and uranium-reducing microbial communities

    SciTech Connect (OSTI)

    Cardenas, Erick [Michigan State University, East Lansing; Wu, Wei-min [Stanford University; Leigh, Mary Beth [Michigan State University, East Lansing; Carley, Jack M [ORNL; Carroll, Sue L [ORNL; Gentry, Terry [Texas A& M University; Luo, Jian [Georgia Institute of Technology; Watson, David B [ORNL; Gu, Baohua [ORNL; Ginder-Vogel, Matthew A. [Stanford University; Kitanidis, Peter K. [Stanford University; Jardine, Philip [University of Tennessee; Kelly, Shelly D [Argonne National Laboratory (ANL); Zhou, Jizhong [University of Oklahoma, Norman; Criddle, Craig [Stanford University; Marsh, Terence [Michigan State University, East Lansing; Tiedje, James [Michigan State University, East Lansing

    2010-08-01T23:59:59.000Z

    Massively parallel sequencing has provided a more affordable and high throughput method to study microbial communities, although it has been mostly used in an exploratory fashion. We combined pyrosequencing with a strict indicator species statistical analysis to test if bacteria specifically responded to ethanol injection that successfully promoted dissimilatory uranium (VI) reduction in the subsurface of a uranium contamination plume at the Oak Ridge Field Research Center in Tennessee, USA. Remediation was achieved with a hydraulic flow control consisting of an inner loop, where ethanol was injected, and an outer loop for flow field protection. This strategy reduced uranium concentrations in groundwater to levels below 0.126 {micro}M, and created geochemical gradients in electron donors from the inner loop injection well towards the outer loop and down-gradient flow path. Our analysis with 15 sediment samples from the entire test area found significant indicator species that showed a high degree of adaptation to the three different hydrochemical created conditions. Castellaniella, and Rhodanobacter characterized areas with low pH, heavy metals, and low bioactivity; while sulfate-, Fe(III)-, and U(VI)-reducing bacteria (Desulfovibrio, Anaeromyxobacter, and Desulfosporosinus) were indicators of areas where U(VI) reduction occurred. Abundance of these bacteria as well as the Fe(III)- and U(VI)-reducer Geobacter correlated with the hydraulic connectivity to the substrate injection site, suggesting that the selected populations were a direct response to the electron donor addition and by the groundwater flow path. A false discovery rate approach was implemented to discard false positives by chance given the large amount of data compared.

  5. Massively Parallel Part I. Preliminaries

    E-Print Network [OSTI]

    Kaminsky, Alan

    program in that chapter mined (computed the golden nonce for) just one Bitcoin. But suppose I want to mine many Bitcoins, K of them. All I have to do is execute K processes, each process running one thread on one core of the cluster, each process run ning the sequential Bitcoin mining program on a different

  6. Appeared in Proc. of the 6th Symposium on the Frontiers of Massively Parallel Computation, October 1996, pp. 180--187. c

    E-Print Network [OSTI]

    Gropp, Bill

    , it is a strategy for implementing other APIs. The rest of the paper is organized as follows. In Sec­ tion 2, we have defined an abstract­device interface for parallel I/O, called ADIO. Any parallel­I/O API can be imple­ mented on multiple file systems by implementing the API portably on top of ADIO, and implementing

  7. Massive Gravity

    E-Print Network [OSTI]

    Claudia de Rham

    2014-03-14T23:59:59.000Z

    We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali-Gabadadze-Porrati model, cascading gravity and ghost-free massive gravity. We then explore their theoretical and phenomenological consistency, proving the absence of Boulware-Deser ghosts and reviewing the Vainshtein mechanism and the cosmological solutions in these models. Finally we present alternative and related models of massive gravity such as new massive gravity, Lorentz-violating massive gravity and non-local massive gravity.

  8. Method and apparatus for routing data in an inter-nodal communications lattice of a massively parallel computer system by semi-randomly varying routing policies for different packets

    DOE Patents [OSTI]

    Archer, Charles Jens (Rochester, MN); Musselman, Roy Glenn (Rochester, MN); Peters, Amanda (Rochester, MN); Pinnow, Kurt Walter (Rochester, MN); Swartz, Brent Allen (Chippewa Falls, WI); Wallenfelt, Brian Paul (Eden Prairie, MN)

    2010-11-23T23:59:59.000Z

    A massively parallel computer system contains an inter-nodal communications network of node-to-node links. Nodes vary a choice of routing policy for routing data in the network in a semi-random manner, so that similarly situated packets are not always routed along the same path. Semi-random variation of the routing policy tends to avoid certain local hot spots of network activity, which might otherwise arise using more consistent routing determinations. Preferably, the originating node chooses a routing policy for a packet, and all intermediate nodes in the path route the packet according to that policy. Policies may be rotated on a round-robin basis, selected by generating a random number, or otherwise varied.

  9. Parallel computing works

    SciTech Connect (OSTI)

    Not Available

    1991-10-23T23:59:59.000Z

    An account of the Caltech Concurrent Computation Program (C{sup 3}P), a five year project that focused on answering the question: Can parallel computers be used to do large-scale scientific computations '' As the title indicates, the question is answered in the affirmative, by implementing numerous scientific applications on real parallel computers and doing computations that produced new scientific results. In the process of doing so, C{sup 3}P helped design and build several new computers, designed and implemented basic system software, developed algorithms for frequently used mathematical computations on massively parallel machines, devised performance models and measured the performance of many computers, and created a high performance computing facility based exclusively on parallel computers. While the initial focus of C{sup 3}P was the hypercube architecture developed by C. Seitz, many of the methods developed and lessons learned have been applied successfully on other massively parallel architectures.

  10. USER’S GUIDE of TOUGH2-EGS-MP: A Massively Parallel Simulator with Coupled Geomechanics for Fluid and Heat Flow in Enhanced Geothermal Systems VERSION 1.0

    SciTech Connect (OSTI)

    Xiong, Yi [Colorado School of Mines; Fakcharoenphol, Perapon [Colorado School of Mines; Wang, Shihao [Colorado School of Mines; Winterfeld, Philip H. [Colorado School of Mines; Zhang, Keni [Lawrence Berkeley National Laboratory; Wu, Yu-Shu [Colorado School of Mines

    2013-12-01T23:59:59.000Z

    TOUGH2-EGS-MP is a parallel numerical simulation program coupling geomechanics with fluid and heat flow in fractured and porous media, and is applicable for simulation of enhanced geothermal systems (EGS). TOUGH2-EGS-MP is based on the TOUGH2-MP code, the massively parallel version of TOUGH2. In TOUGH2-EGS-MP, the fully-coupled flow-geomechanics model is developed from linear elastic theory for thermo-poro-elastic systems and is formulated in terms of mean normal stress as well as pore pressure and temperature. Reservoir rock properties such as porosity and permeability depend on rock deformation, and the relationships between these two, obtained from poro-elasticity theories and empirical correlations, are incorporated into the simulation. This report provides the user with detailed information on the TOUGH2-EGS-MP mathematical model and instructions for using it for Thermal-Hydrological-Mechanical (THM) simulations. The mathematical model includes the fluid and heat flow equations, geomechanical equation, and discretization of those equations. In addition, the parallel aspects of the code, such as domain partitioning and communication between processors, are also included. Although TOUGH2-EGS-MP has the capability for simulating fluid and heat flows coupled with geomechanical effects, it is up to the user to select the specific coupling process, such as THM or only TH, in a simulation. There are several example problems illustrating applications of this program. These example problems are described in detail and their input data are presented. Their results demonstrate that this program can be used for field-scale geothermal reservoir simulation in porous and fractured media with fluid and heat flow coupled with geomechanical effects.

  11. Massively parallel molecular dynamics simulations of

    E-Print Network [OSTI]

    Berne, Bruce J.

    experimental studies pioneered by Dobson and coworkers have shown that amyloids and fibrils can be formed of their three- dimensional (3D) structure and dynamics at the atomic level. This understanding can not only from the traditional beta-amyloid peptides but also from almost any proteins, such as lysozyme

  12. Massively Parallel Computation of Discrete Logarithms \\Lambda

    E-Print Network [OSTI]

    McCurley, Kevin

    an order of magnitude using such an analysis. Among the reasons for this are: ffl if a high­level language, keeping in mind that log g a is only determined modulo the multiplicative order of g. For general be extremely useful to chart the increase in difficulty of computing discrete logarithms as the field size

  13. Massively Parallel Computation of Discrete Logarithms

    E-Print Network [OSTI]

    Gordon, Dan

    an order of magnitude using such an analysis. Among the reasons for this are: · if a high-level language, keeping in mind that logg a is only determined modulo the multiplicative order of g. For general be extremely useful to chart the increase in difficulty of computing discrete logarithms as the field size

  14. Scalable Parallel File System for Data and Metadata-intensive...

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

    Host: Rob Ross A critical purpose for parallel file systems used in high performance computing is to capture quickly and durably hold checkpoints of long running massive...

  15. Algorithms for VLSI Circuit Optimization and GPU-Based Parallelization

    E-Print Network [OSTI]

    Liu, Yifang

    2010-07-14T23:59:59.000Z

    processing unit (GPGPU) technology provides massive parallel computing power. This research turns the complex computation task of circuit optimization into many subtasks processed by parallel threads. The proposed task partitioning and scheduling methods take...

  16. Parallel MATLAB: Parallel For Loops

    E-Print Network [OSTI]

    Crawford, T. Daniel

    Parallel MATLAB: Parallel For Loops John Burkardt (FSU) Gene Cliff (AOE/ICAM - ecliff Research Computing ICAM: Interdisciplinary Center for Applied Mathematics 1 / 69 #12;MATLAB Parallel Example ODE SWEEP Example FMINCON Example Conclusion 2 / 69 #12;INTRO: Parallel MATLAB Parallel MATLAB

  17. Massive Hopfions

    E-Print Network [OSTI]

    David Foster

    2010-12-12T23:59:59.000Z

    The Skyrme-Faddeev model is a (3+1)-dimensional model which has knotted, string-like, soliton solutions. In this paper we investigate a Skyrme-Faddeev model with an SO(3) symmetry breaking potential. We then rescale this model and take the mass to infinity. This infinite mass model is found to have compact knotted solutions. In all of the investigated massive models we find similar charged solutions as in the usual, m=0, model. We also find that their energies follow a similar power growth as the m=0 model.

  18. Cluster Parallel Loops Part I. Preliminaries

    E-Print Network [OSTI]

    Kaminsky, Alan

    ;14­2 BIG CPU, BIG DATA he massively parallel Bitcoin mining program in Chapter 13 still doesn't take full advantage of the cluster's parallel processing capabilities. Each Bitcoin mining task uses all the cores on just one node. So on the 10-node tardis cluster, I have to mine 10 or more Bitcoins to fully utilize

  19. Hybrid Parallel Part I. Preliminaries

    E-Print Network [OSTI]

    Kaminsky, Alan

    ;13­2 BIG CPU, BIG DATA he massively parallel Bitcoin mining program in Chapter 11 doesn't nec essarily take each Bitcoin sequentially on a single core, I have to mine 40 or more Bitcoins to take full advantage of the cluster. If I mine fewer than 40 Bitcoins, some of the cores will be idle. That's not good. I want to put

  20. Scheduling of real-time communication network for parallel processing

    E-Print Network [OSTI]

    Li, Hung

    2012-06-07T23:59:59.000Z

    very attractive for the next generation real-time systems. How to support realtime communication on the massively parallel computers becomes an important issue. This project focuses on wormhole networks of Paragon, and study different transmission...

  1. Parallel MATLAB at VT: Parallel For Loops

    E-Print Network [OSTI]

    Crawford, T. Daniel

    Parallel MATLAB at VT: Parallel For Loops John Burkardt (FSU) Gene Cliff (AOE/ICAM - ecliff Research Computing ICAM: Interdisciplinary Center for Applied Mathematics 1 / 72 #12;MATLAB Parallel Example ODE SWEEP Example FMINCON Example Conclusion 2 / 72 #12;INTRO: Parallel MATLAB Parallel MATLAB

  2. Parallel MATLAB at VT: Parallel For Loops

    E-Print Network [OSTI]

    Crawford, T. Daniel

    Parallel MATLAB at VT: Parallel For Loops John Burkardt (FSU) Gene Cliff (AOE/ICAM - ecliff Research Computing ICAM: Interdisciplinary Center for Applied Mathematics 1 / 71 #12;MATLAB Parallel Example ODE SWEEP Example FMINCON Example Conclusion 2 / 71 #12;INTRO: Parallel MATLAB Parallel MATLAB

  3. APPLAUSE: Applications Using the ElipSys Parallel CLP System

    E-Print Network [OSTI]

    Panagiotis, Stamatopoulos

    of Parallel Programming Us- ing Logic) Project is building major applications using the ElipSys par- allel, possibly massive, search spaces can be explored in parallel. 5 Environmental Monitoring and Control: Sys concerned with the monitoring and control of pollution in the Venice Lagoon as a demonstrator for the Venice

  4. Parallel MATLAB at VT: Parallel For Loops

    E-Print Network [OSTI]

    Crawford, T. Daniel

    Parallel MATLAB at VT: Parallel For Loops John Burkardt (FSU) Gene Cliff (AOE/ICAM - ecliff Research Computing ICAM: Interdisciplinary Center for Applied Mathematics 1 / 56 #12;Matlab Parallel ODE SWEEP Example MD Example Conclusion 2 / 56 #12;INTRO: Parallel Matlab In a previous lecture we

  5. Stability of Solutions of Hydrodynamic Equations Describing the Scaling Limit of a Massive Piston in an

    E-Print Network [OSTI]

    Chernov, Nikolai

    Stability of Solutions of Hydrodynamic Equations Describing the Scaling Limit of a Massive Piston of a system con- sisting of a massive piston immersed in an ideal gas of point particles in a box. We find of a system consisting of a piston of mass M moving parallel to the x-axis in a cube containing non

  6. Massively Parallel Asset and Liability Andreas Grothey1

    E-Print Network [OSTI]

    Grothey, Andreas

    (in particular Interior Point Methods) and the use of High Performance Computing techniques have made measures can be integrated into the framework and address the issue of modelling for High Performance Computing. 1 Introduction Asset and Liability Management (ALM) is one of the most important applica- tions

  7. I High-Performance I/O for Massively Parallel

    E-Print Network [OSTI]

    Kuzmanovic, Aleksandar

    -100 files/run. 20-200 MBps. l-10 Gbytes. HiPPl bandwidths minimum. 1 Tbyte. Secondary I/O bandwidth disk, 50-100 MBps disk to 3-inch storage (comparable to HiPPl/Ultra). 1 Tbyte. 0.5 GBps to disk, 45

  8. Massively parallel structured direct solver for equations describing ...

    E-Print Network [OSTI]

    2011-10-17T23:59:59.000Z

    on a large domain, for a large number of different sources. ..... the symmetry axis is given by the third column of R?,?. ..... the green dashed line in figure ? ... of anisotropy in RTM and FWI has been widely recognized as important in real-

  9. Mapping the Hallmarks of Lung Adenocarcinoma with Massively Parallel Sequencing

    E-Print Network [OSTI]

    Lander, Eric S.

    Lung adenocarcinoma, the most common subtype of non-small cell lung cancer, is responsible for more than 500,000 deaths per year worldwide. Here, we report exome and genome sequences of 183 lung adenocarcinoma tumor/normal ...

  10. Fitting FFT onto an Energy Efficient Massively Parallel Architecture

    E-Print Network [OSTI]

    Andonie, Razvan

    and Computers Department Transylvania University of Bra¸sov, Romania and Splash Software, Bra¸sov, Romania, USA and Electronics and Computers Department Transylvania University of Bra¸sov, Romania andonie

  11. Massively parallel DNA sequencing: the new frontier in biogeography

    E-Print Network [OSTI]

    Rocha, Luiz A.; Bernal, Moisés A.; Gaither, Michelle R.; Alfaro, Michael E.

    2013-01-01T23:59:59.000Z

    Edited by Rita Castilho  frontiers of biogeography 5.1, Heaney, L.R.  (2004) Frontiers of biogeogra? phy:  new producing  a  robust  frontiers of biogeography 5.1, 2013 — 

  12. Distributed Dense Numerical Linear Algebra Algorithms on massively parallel architectures

    E-Print Network [OSTI]

    Boyer, Edmond

    by a stubborn set of physical barriers: excess heat produced, too much power consumed, too much voltage leaked prioritization, architecture-aware scheduling and management of micro-tasks on distributed architectures in a distributed system. We demonstrate from our preliminary results that our DAG-based approach has the potential

  13. Discontinuous Methods for Accurate, Massively Parallel Quantum Molecular

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsruc DocumentationP-Series to UserProduct:Directives Templates byInformationDisclosures No.

  14. Resummation of Massive Gravity

    SciTech Connect (OSTI)

    Rham, Claudia de [Department de Physique Theorique, Universite de Geneve, 24 Quai E. Ansermet, CH-1211 Geneve (Switzerland); Gabadadze, Gregory [Center for Cosmology and Particle Physics, Department of Physics, New York University, New York 10003 (United States); Tolley, Andrew J. [Department of Physics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106 (United States)

    2011-06-10T23:59:59.000Z

    We construct four-dimensional covariant nonlinear theories of massive gravity which are ghost-free in the decoupling limit to all orders. These theories resume explicitly all the nonlinear terms of an effective field theory of massive gravity. We show that away from the decoupling limit the Hamiltonian constraint is maintained at least up to and including quartic order in nonlinearities, hence excluding the possibility of the Boulware-Deser ghost up to this order. We also show that the same remains true to all orders in a similar toy model.

  15. Supertwistors and massive particles

    SciTech Connect (OSTI)

    Mezincescu, Luca, E-mail: mezincescu@server.physics.miami.edu [Department of Physics, University of Miami, Coral Gables, FL 33124 (United States); Routh, Alasdair J., E-mail: a.j.routh@damtp.cam.ac.uk [DAMTP, CMS, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Townsend, Paul K., E-mail: p.k.townsend@damtp.cam.ac.uk [DAMTP, CMS, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

    2014-07-15T23:59:59.000Z

    In the (super)twistor formulation of massless (super)particle mechanics, the mass-shell constraint is replaced by a “spin-shell” constraint from which the spin content can be read off. We extend this formalism to massive (super)particles (with N-extended space–time supersymmetry) in three and four space–time dimensions, explaining how the spin-shell constraints are related to spin, and we use it to prove equivalence of the massive N=1 and BPS-saturated N=2 superparticle actions. We also find the supertwistor form of the action for “spinning particles” with N-extended worldline supersymmetry, massless in four dimensions and massive in three dimensions, and we show how this simplifies special features of the N=2 case. -- Highlights: •Spin-shell constraints are related to Poincaré Casimirs. •Twistor form of 4D spinning particle for spin N/2. •Twistor proof of scalar/antisymmetric tensor equivalence for 4D spin 0. •Twistor form of 3D particle with arbitrary spin. •Proof of equivalence of N=1 and N=2 BPS massive 4D superparticles.

  16. Observing Massive Galaxy Formation

    E-Print Network [OSTI]

    Christopher J. Conselice

    2002-12-20T23:59:59.000Z

    A major goal of contemporary astrophysics is understanding the origin of the most massive galaxies in the universe, particularly nearby ellipticals and spirals. Theoretical models of galaxy formation have existed for many decades, although low and high redshift observations are only beginning to put constraints on different ideas. We briefly describe these observations and how they are revealing the methods by which galaxies form by contrasting and comparing fiducial rapid collapse and hierarchical formation model predictions. The available data show that cluster ellipticals must have rapidly formed at z > 2, and that up to 50% of all massive galaxies at z ~ 2.5 are involved in major mergers. While the former is consistent with the monolithic collapse picture, we argue that hierarchal formation is the only model that can reproduce all the available observations.

  17. A novel polymeric microelectrode array for highly parallel, long-term neuronal culture and stimulation

    E-Print Network [OSTI]

    Talei Franzesi, Giovanni

    2008-01-01T23:59:59.000Z

    Cell-based high-throughput screening is emerging as a disruptive technology in drug discovery; however, massively parallel electrical assaying of neurons and cardiomyocites has until now been prohibitively expensive. To ...

  18. Parallelization of the Value-Iteration algorithm for

    E-Print Network [OSTI]

    and stochastic environment. To determine the solution of a POMDP, algorithms with a running time in the PSPACE using the massive parallel processing power of modern Graphic Processing Units (GPU). Our experiments synchronization features are needed to exploit the full potential. #12;ii #12;Summary (Danish) Delvist

  19. Parallel flow diffusion battery

    DOE Patents [OSTI]

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

    1984-01-01T23:59:59.000Z

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

  20. Massive neutrinos and cosmology

    E-Print Network [OSTI]

    Julien Lesgourgues; Sergio Pastor

    2006-05-29T23:59:59.000Z

    The present experimental results on neutrino flavour oscillations provide evidence for non-zero neutrino masses, but give no hint on their absolute mass scale, which is the target of beta decay and neutrinoless double-beta decay experiments. Crucial complementary information on neutrino masses can be obtained from the analysis of data on cosmological observables, such as the anisotropies of the cosmic microwave background or the distribution of large-scale structure. In this review we describe in detail how free-streaming massive neutrinos affect the evolution of cosmological perturbations. We summarize the current bounds on the sum of neutrino masses that can be derived from various combinations of cosmological data, including the most recent analysis by the WMAP team. We also discuss how future cosmological experiments are expected to be sensitive to neutrino masses well into the sub-eV range.

  1. Parallel Astronomical Data Processing with Python: Recipes for multicore machines

    E-Print Network [OSTI]

    Singh, Navtej; Butler, Ray

    2013-01-01T23:59:59.000Z

    High performance computing has been used in various fields of astrophysical research. But most of it is implemented on massively parallel systems (supercomputers) or graphical processing unit clusters. With the advent of multicore processors in the last decade, many serial software codes have been re-implemented in parallel mode to utilize the full potential of these processors. In this paper, we propose parallel processing recipes for multicore machines for astronomical data processing. The target audience are astronomers who are using Python as their preferred scripting language and who may be using PyRAF/IRAF for data processing. Three problems of varied complexity were benchmarked on three different types of multicore processors to demonstrate the benefits, in terms of execution time, of parallelizing data processing tasks. The native multiprocessing module available in Python makes it a relatively trivial task to implement the parallel code. We have also compared the three multiprocessing approaches - Po...

  2. Massively Deployed Sensors Final Project Report

    E-Print Network [OSTI]

    Massively Deployed Sensors Final Project Report Power Systems Engineering Research Center Systems Engineering Research Center Massively Deployed Sensors Final Project Report Editors Jonathan project titled "Massively Deployed Sensors," PSERC project T-31. We express our appreciation

  3. Electromagnetic properties of massive neutrinos

    SciTech Connect (OSTI)

    Dobrynina, A. A., E-mail: aleksandradobrynina@rambler.ru; Mikheev, N. V.; Narynskaya, E. N. [Demidov Yaroslavl State University (Russian Federation)] [Demidov Yaroslavl State University (Russian Federation)

    2013-10-15T23:59:59.000Z

    The vertex function for a virtual massive neutrino is calculated in the limit of soft real photons. A method based on employing the neutrino self-energy operator in a weak external electromagnetic field in the approximation linear in the field is developed in order to render this calculation of the vertex function convenient. It is shown that the electric charge and the electric dipole moment of the real neutrino are zero; only the magnetic moment is nonzero for massive neutrinos. A fourth-generation heavy neutrino of mass not less than half of the Z-boson mass is considered as a massive neutrino.

  4. Parallel digital forensics infrastructure.

    SciTech Connect (OSTI)

    Liebrock, Lorie M. (New Mexico Tech, Socorro, NM); Duggan, David Patrick

    2009-10-01T23:59:59.000Z

    This report documents the architecture and implementation of a Parallel Digital Forensics infrastructure. This infrastructure is necessary for supporting the design, implementation, and testing of new classes of parallel digital forensics tools. Digital Forensics has become extremely difficult with data sets of one terabyte and larger. The only way to overcome the processing time of these large sets is to identify and develop new parallel algorithms for performing the analysis. To support algorithm research, a flexible base infrastructure is required. A candidate architecture for this base infrastructure was designed, instantiated, and tested by this project, in collaboration with New Mexico Tech. Previous infrastructures were not designed and built specifically for the development and testing of parallel algorithms. With the size of forensics data sets only expected to increase significantly, this type of infrastructure support is necessary for continued research in parallel digital forensics. This report documents the implementation of the parallel digital forensics (PDF) infrastructure architecture and implementation.

  5. Parallel integrated thermal management

    DOE Patents [OSTI]

    Bennion, Kevin; Thornton, Matthew

    2014-08-19T23:59:59.000Z

    Embodiments discussed herein are directed to managing the heat content of two vehicle subsystems through a single coolant loop having parallel branches for each subsystem.

  6. Real-time parallel computation and visualization of ultrasonic pulses in solids

    SciTech Connect (OSTI)

    Schechter, R.S.; Chaskelis, H.H.; Mignogna, R.B.; Delsanto, P.P. [Naval Research Lab, Washington, DC (United States)

    1994-08-01T23:59:59.000Z

    Parallel processing has changed the way much computational physics is done. Areas such as condensed matter physics, fluid dynamics, and other fields are making use of massively parallel computers to solve immense and important problems in new ways. Simulating wave propagation is another area that has benefited through the use of parallel processing. This is graphically illustrated in this article by various numerical simulations of ultrasonic pulses propagating through solids carried out on a massively parallel computer. These computations are accompanied by visualizations of the resulting wavefield. The calculations and visualizations, together, can be completed in only seconds to several minutes and compare well with experimental data. The computations and parallel processing techniques described should be important in related fields, such as geophysics, acoustics, and mechanics. 19 refs.

  7. An efficient parallel algorithm for matrix-vector multiplication

    SciTech Connect (OSTI)

    Hendrickson, B.; Leland, R.; Plimpton, S.

    1993-03-01T23:59:59.000Z

    The multiplication of a vector by a matrix is the kernel computation of many algorithms in scientific computation. A fast parallel algorithm for this calculation is therefore necessary if one is to make full use of the new generation of parallel supercomputers. This paper presents a high performance, parallel matrix-vector multiplication algorithm that is particularly well suited to hypercube multiprocessors. For an n x n matrix on p processors, the communication cost of this algorithm is O(n/[radical]p + log(p)), independent of the matrix sparsity pattern. The performance of the algorithm is demonstrated by employing it as the kernel in the well-known NAS conjugate gradient benchmark, where a run time of 6.09 seconds was observed. This is the best published performance on this benchmark achieved to date using a massively parallel supercomputer.

  8. Large-Scale Molecular Dynamics Simulations for Highly Parallel Infrastructures

    E-Print Network [OSTI]

    Pazúriková, Jana

    2014-01-01T23:59:59.000Z

    Computational chemistry allows researchers to experiment in sillico: by running a computer simulations of a biological or chemical processes of interest. Molecular dynamics with molecular mechanics model of interactions simulates N-body problem of atoms$-$it computes movements of atoms according to Newtonian physics and empirical descriptions of atomic electrostatic interactions. These simulations require high performance computing resources, as evaluations within each step are computationally demanding and billions of steps are needed to reach interesting timescales. Current methods decompose the spatial domain of the problem and calculate on parallel/distributed infrastructures. Even the methods with the highest strong scaling hit the limit at half a million cores: they are not able to cut the time to result if provided with more processors. At the dawn of exascale computing with massively parallel computational resources, we want to increase the level of parallelism by incorporating parallel-in-time comput...

  9. Black Holes with Quantum Massive Spin-2 Hair

    E-Print Network [OSTI]

    Gia Dvali

    2006-05-31T23:59:59.000Z

    We show that black holes can posses a long range quantum mechanical hair associated with a massive spin-2 field, which can be detected by a stringy generalization of the Aharovon-Bohm effect, in which a string loop lassoes the black hole. The long distance effect persist for arbitrarily high mass of the spin-2 field. An analogous effect is exhibited by a massive antisymmetric two-form field. We make a close parallel between the two and the ordinary Aharonov-Bohm phenomenon, and also show that in the latter case the effect can be experienced even by the electrically-neutral particles, provided some boundary terms are added to the action.

  10. Towards Pervasive Parallelism Kunle Olukotun

    E-Print Network [OSTI]

    John, Lizy Kurian

    development practical for the masses Not parallel programming as usual PPL is a combination of Leading vision for pervasive parallelism #12;The PPL Team Applications Ron Fedkiw, Vladlen Koltun, Sebastian: Parallel applications without parallel programming #12;The PPL Vision Parallel Object Language Hardware

  11. Radiation transport on unstructured mesh with parallel computers

    SciTech Connect (OSTI)

    Fan, W.C.; Drumm, C.R.

    2000-07-01T23:59:59.000Z

    This paper summarizes the developmental work on a deterministic transport code that provides multidimensional radiation transport capabilities on an unstructured mesh. The second-order form of the Boltzmann transport equation is solved utilizing the discrete ordinates angular differencing and the Galerkin finite element spatial differencing. The discretized system, which couples the spatial-angular dependence, is solved simultaneously using a parallel conjugate-gradient (CG) iterative solver. This approach eliminates the need for the conventional inner iterations over the discrete directions and is well-suited for massively parallel computers.

  12. Parallel programming with PCN

    SciTech Connect (OSTI)

    Foster, I.; Tuecke, S.

    1991-12-01T23:59:59.000Z

    PCN is a system for developing and executing parallel programs. It comprises a high-level programming language, tools for developing and debugging programs in this language, and interfaces to Fortran and C that allow the reuse of existing code in multilingual parallel programs. Programs developed using PCN are portable across many different workstations, networks, and parallel computers. This document provides all the information required to develop parallel programs with the PCN programming system. In includes both tutorial and reference material. It also presents the basic concepts that underly PCN, particularly where these are likely to be unfamiliar to the reader, and provides pointers to other documentation on the PCN language, programming techniques, and tools. PCN is in the public domain. The latest version of both the software and this manual can be obtained by anonymous FTP from Argonne National Laboratory in the directory pub/pcn at info.mcs.anl.gov (c.f. Appendix A).

  13. A Stable Massive Charged Particle

    E-Print Network [OSTI]

    G. Rajasekaran

    2011-06-08T23:59:59.000Z

    We consider the possibility of the existence of a stable massive charged particle by a minimal extension of the standard model particle content. Absolute stability in the case of singly charged particle is not possible if the usual doublet Higgs exists, unless a discrete symmetry is imposed.But a doubly charged particle is absolutely stable.

  14. Parallel Matlab MIT Lincoln Laboratory

    E-Print Network [OSTI]

    Kepner, Jeremy

    Slide-1 Parallel Matlab MIT Lincoln Laboratory Parallel Matlab: The Next Generation Dr. Jeremy Lincoln LaboratorySlide-2 Parallel Matlab · Motivation · Challenges Outline · Introduction · Approach · Performance Results · Future Work and Summary #12;MIT Lincoln LaboratorySlide-3 Parallel Matlab Motivation: Do

  15. Massivizing Online Games: Distributed Computing Challenges and

    E-Print Network [OSTI]

    Iosup, Alexandru

    Massivizing Online Social Games Scheduling in IaaS Clouds Gamification in Higher Education May 9 May 27 June 5

  16. Black holes with massive graviton hair

    E-Print Network [OSTI]

    Richard Brito; Vitor Cardoso; Paolo Pani

    2013-09-03T23:59:59.000Z

    No-hair theorems exclude the existence of nontrivial scalar and massive vector hair outside four-dimensional, static, asymptotically flat black-hole spacetimes. We show, by explicitly building nonlinear solutions, that black holes can support massive graviton hair in theories of massive gravity. These hairy solutions are, most likely, the generic end state of the recently discovered monopole instability of Schwarzschild black holes in massive graviton theories.

  17. Final Report -- Center for Programmng Models for Scalable Parallel Computing (UIUC subgroup)

    SciTech Connect (OSTI)

    Marianne Winslett; Michael Folk

    2007-03-31T23:59:59.000Z

    The mission of the Center for Scalable Programming Models (Pmodels) was to create new ways of programming parallel computers that are much easier for humans to conceptualize, that allow programs to be written, updated and debugged quickly, and that run extremely efficiently---even on computers with thousands or even millions of processors. At UIUC, our work for Pmodels focused on support for I/O in a massively parallel environment, and included both research and technology transfer activities.

  18. Parallel optical sampler

    DOE Patents [OSTI]

    Tauke-Pedretti, Anna; Skogen, Erik J; Vawter, Gregory A

    2014-05-20T23:59:59.000Z

    An optical sampler includes a first and second 1.times.n optical beam splitters splitting an input optical sampling signal and an optical analog input signal into n parallel channels, respectively, a plurality of optical delay elements providing n parallel delayed input optical sampling signals, n photodiodes converting the n parallel optical analog input signals into n respective electrical output signals, and n optical modulators modulating the input optical sampling signal or the optical analog input signal by the respective electrical output signals, and providing n successive optical samples of the optical analog input signal. A plurality of output photodiodes and eADCs convert the n successive optical samples to n successive digital samples. The optical modulator may be a photodiode interconnected Mach-Zehnder Modulator. A method of sampling the optical analog input signal is disclosed.

  19. X-ray Emission from Massive Stars

    E-Print Network [OSTI]

    Cohen, David

    X-ray Emission from Massive Stars David Cohen Department of Physics and Astronomy Swarthmore be related to the production of X-rays on massive stars. If so, massive stars' X-rays are much different than those found our own Sun and other cooler stars like the Sun that produce X-rays via magnetic activity

  20. Massive Stars and their Supernovae

    E-Print Network [OSTI]

    Thielemann, Friedrich-Karl; Liebendörfer, Matthias; Diehl, Roland; 10.1007/978-3-642-12698-7_4

    2010-01-01T23:59:59.000Z

    Massive stars and their supernovae are prominent sources of radioactive isotopes, the observations of which thus can help to improve our astrophysical models of those. Our understanding of stellar evolution and the final explosive endpoints such as supernovae or hypernovae or gamma-ray bursts relies on the combination of magneto-hydrodynamics, energy generation due to nuclear reactions accompanying composition changes, radiation transport, and thermodynamic properties (such as the equation of state of stellar matter). Nuclear energy production includes all nuclear reactions triggered during stellar evolution and explosive end stages, also among unstable isotopes produced on the way. Radiation transport covers atomic physics (e.g. opacities) for photon transport, but also nuclear physics and neutrino nucleon/nucleus interactions in late phases and core collapse. Here we want to focus on the astrophysical aspects, i.e. a description of the evolution of massive stars and their endpoints, with a special emphasis ...

  1. Black holes in massive gravity

    E-Print Network [OSTI]

    Babichev, Eugeny

    2015-01-01T23:59:59.000Z

    We review the black hole solutions of the ghost-free massive gravity theory and its bimetric extension and outline the main results on the stability of these solutions against small perturbations. Massive (bi)-gravity accommodates exact black hole solutions, analogous to those of General Relativity. In addition to these solutions, hairy black holes -- solutions with no correspondent in General Relativity -- have been found numerically, whose existence is a natural consequence of the absence of the Birkhoff's theorem in these theories. The existence of extra propagating degrees of freedom, makes the stability properties of these black holes richer and more complex than those of General Relativity. In particular, the bi-Schwarzschild black hole exhibits an unstable spherically symmetric mode, while the bi-Kerr geometry is also generically unstable, both against the spherical mode and against superradiant instabilities. If astrophysical black holes are described by these solutions, the superradiant instability o...

  2. Allinea DDT as a Parallel Debugging Alternative to Totalview

    SciTech Connect (OSTI)

    Antypas, K.B.

    2007-03-05T23:59:59.000Z

    Totalview, from the Etnus Corporation, is a sophisticated and feature rich software debugger for parallel applications. As Totalview has gained in popularity and market share its pricing model has increased to the point where it is often prohibitively expensive for massively parallel supercomputers. Additionally, many of Totalview's advanced features are not used by members of the scientific computing community. For these reasons, supercomputing centers have begun to search for a basic parallel debugging tool which can be used as an alternative to Totalview. As the cost and complexity of Totalview has increased over the years, scientific computing centers have started searching for a viable parallel debugging alternative. DDT (Distributed Debugging Tool) from Allinea Software is a relatively new parallel debugging tool which aims to provide much of the same functionality as Totalview. This review outlines the basic features and limitations of DDT to determine if it can be a reasonable substitute for Totalview. DDT was tested on the NERSC platforms Bassi, Seaborg, Jacquard and Davinci with Fortran90, C, and C++ codes using MPI and OpenMP for parallelism.

  3. Parallel Seismic Ray Tracing

    E-Print Network [OSTI]

    Jain, Tarun K

    2013-12-09T23:59:59.000Z

    of the method while others are intended to be representative of basic geological features such as salt domes. We also present a theoretical model to understand the performance of the pWFC algorithm. We evaluate the performance of the proposed parallel...

  4. Parallel programming with PCN

    SciTech Connect (OSTI)

    Foster, I.; Tuecke, S.

    1993-01-01T23:59:59.000Z

    PCN is a system for developing and executing parallel programs. It comprises a high-level programming language, tools for developing and debugging programs in this language, and interfaces to Fortran and Cthat allow the reuse of existing code in multilingual parallel programs. Programs developed using PCN are portable across many different workstations, networks, and parallel computers. This document provides all the information required to develop parallel programs with the PCN programming system. It includes both tutorial and reference material. It also presents the basic concepts that underlie PCN, particularly where these are likely to be unfamiliar to the reader, and provides pointers to other documentation on the PCN language, programming techniques, and tools. PCN is in the public domain. The latest version of both the software and this manual can be obtained by anonymous ftp from Argonne National Laboratory in the directory pub/pcn at info.mcs. ani.gov (cf. Appendix A). This version of this document describes PCN version 2.0, a major revision of the PCN programming system. It supersedes earlier versions of this report.

  5. The massive transformation in Ti-Al alloys: mechanistic observations

    SciTech Connect (OSTI)

    Zhang, X.D.; Godfrey, S.; Weaver, M.; Strangwood, M.; Kaufman, M.J.; Loretto, M.H. [Univ. of Birmingham, Edgbaston (United Kingdom). IRC in Materials for High Performance Applications] [Univ. of Birmingham, Edgbaston (United Kingdom). IRC in Materials for High Performance Applications; Threadgill, P. [Univ. of Birmingham, Edgbaston (United Kingdom). IRC in Materials for High Performance Applications] [Univ. of Birmingham, Edgbaston (United Kingdom). IRC in Materials for High Performance Applications; [TWI, Cambridge (United Kingdom)

    1996-09-01T23:59:59.000Z

    The massive {alpha}{yields}{gamma}{sub m} transformation, as observed using analytical transmission electron microscopy, in Ti-49Al, Ti-48Al-2Nb-2Mn, Ti-55Al-25Ta and Ti-50Al-20Ta alloys is described. Conventional solution heating and quenching experiments have been combined with the more rapid quenching possible using electron beam melting in order to provide further insight into the early stages of the transformation of these alloys. It is shown that the {gamma} develops first at grain boundaries as lamellae in one of the grains and that these lamellae intersect and spread into the adjacent grain in a massive manner. Consequently, there is no orientation relationship between the massive gamma ({gamma}{sub m}) and the grain being consumed whereas there is the expected relation between the {gamma}{sub m} and the first grain which is inherited from the lamellae. It is further shown that the {gamma}{sub m} grows as an f.c.c. phase after initially growing with the L1{sub 0} structure. Furthermore, it is shown that the massive f.c.c. phase then orders to the L1{sub 0} structure producing APDB-like defects which are actually thin 90{degree} domains separating adjacent domains that have the same orientation yet are out of phase. The advancing {gamma}{sub m} interface tends to facet parallel either to one of its four {l_brace}111{r_brace} planes or to the basal plane in the grain being consumed by impinging on existing {gamma} lamellae. Thin microtwins and {alpha}{sub 2} platelets then form in the {gamma}{sub m} presumably due, respectively, to transformation stresses and supersaturation of the {gamma}{sub m} with titanium for alloys containing {approximately}48% Al; indeed, there is a local depletion in aluminium across the {alpha}{sub 2} platelets as determined using fine probe microanalysis.

  6. Parallel clustering with CFinder

    E-Print Network [OSTI]

    Pollner, Peter; Vicsek, Tamas; 10.1142/S0129626412400014

    2012-01-01T23:59:59.000Z

    The amount of available data about complex systems is increasing every year, measurements of larger and larger systems are collected and recorded. A natural representation of such data is given by networks, whose size is following the size of the original system. The current trend of multiple cores in computing infrastructures call for a parallel reimplementation of earlier methods. Here we present the grid version of CFinder, which can locate overlapping communities in directed, weighted or undirected networks based on the clique percolation method (CPM). We show that the computation of the communities can be distributed among several CPU-s or computers. Although switching to the parallel version not necessarily leads to gain in computing time, it definitely makes the community structure of extremely large networks accessible.

  7. Parallel Transports in Webs

    E-Print Network [OSTI]

    Christian Fleischhack

    2003-07-17T23:59:59.000Z

    For connected reductive linear algebraic structure groups it is proven that every web is holonomically isolated. The possible tuples of parallel transports in a web form a Lie subgroup of the corresponding power of the structure group. This Lie subgroup is explicitly calculated and turns out to be independent of the chosen local trivializations. Moreover, explicit necessary and sufficient criteria for the holonomical independence of webs are derived. The results above can even be sharpened: Given an arbitrary neighbourhood of the base points of a web, then this neighbourhood contains some segments of the web whose parameter intervals coincide, but do not include 0 (that corresponds to the base points of the web), and whose parallel transports already form the same Lie subgroup as those of the full web do.

  8. On parallel machine scheduling 1

    E-Print Network [OSTI]

    Magdeburg, Universität

    On parallel machine scheduling 1 machines with setup times. The setup has to be performed by a single server. The objective is to minimize even for the case of two identical parallel machines. This paper presents a pseudopolynomial

  9. Xyce parallel electronic simulator.

    SciTech Connect (OSTI)

    Keiter, Eric Richard; Mei, Ting; Russo, Thomas V.; Rankin, Eric Lamont; Schiek, Richard Louis; Thornquist, Heidi K.; Fixel, Deborah A.; Coffey, Todd Stirling; Pawlowski, Roger Patrick; Santarelli, Keith R.

    2010-05-01T23:59:59.000Z

    This document is a reference guide to the Xyce Parallel Electronic Simulator, and is a companion document to the Xyce Users' Guide. The focus of this document is (to the extent possible) exhaustively list device parameters, solver options, parser options, and other usage details of Xyce. This document is not intended to be a tutorial. Users who are new to circuit simulation are better served by the Xyce Users' Guide.

  10. Parallel Worldline Numerics: Implementation and Error Analysis

    E-Print Network [OSTI]

    Dan Mazur; Jeremy S. Heyl

    2014-07-28T23:59:59.000Z

    We give an overview of the worldline numerics technique, and discuss the parallel CUDA implementation of a worldline numerics algorithm. In the worldline numerics technique, we wish to generate an ensemble of representative closed-loop particle trajectories, and use these to compute an approximate average value for Wilson loops. We show how this can be done with a specific emphasis on cylindrically symmetric magnetic fields. The fine-grained, massive parallelism provided by the GPU architecture results in considerable speedup in computing Wilson loop averages. Furthermore, we give a brief overview of uncertainty analysis in the worldline numerics method. There are uncertainties from discretizing each loop, and from using a statistical ensemble of representative loops. The former can be minimized so that the latter dominates. However, determining the statistical uncertainties is complicated by two subtleties. Firstly, the distributions generated by the worldline ensembles are highly non-Gaussian, and so the standard error in the mean is not a good measure of the statistical uncertainty. Secondly, because the same ensemble of worldlines is used to compute the Wilson loops at different values of $T$ and $x_\\mathrm{ cm}$, the uncertainties associated with each computed value of the integrand are strongly correlated. We recommend a form of jackknife analysis which deals with both of these problems.

  11. Parallel algorithms for inductance extraction

    E-Print Network [OSTI]

    Mahawar, Hemant

    2007-09-17T23:59:59.000Z

    . . . . . . . . . . . . . . . . . . . . . . . . . 30 3. Pin Connect . . . . . . . . . . . . . . . . . . . . . . . . . 31 C. The Inductance Extraction Algorithm . . . . . . . . . . . . . . 33 ix CHAPTER Page V COMPARISON WITH EXISTING WORK . . . . . . . . . . . . . 35 A. Ground Plane... . . . . . . . . . . . . . . . . . . . . . . . 52 1. Shared Memory Parallelization . . . . . . . . . . . . . . . 53 2. Mixed Mode Parallelization . . . . . . . . . . . . . . . . . 55 3. Distributed Memory Parallelization . . . . . . . . . . . . . 56 VII CONCLUSIONS...

  12. Computer Assisted Parallel Program Generation

    E-Print Network [OSTI]

    Kawata, Shigeo

    2015-01-01T23:59:59.000Z

    Parallel computation is widely employed in scientific researches, engineering activities and product development. Parallel program writing itself is not always a simple task depending on problems solved. Large-scale scientific computing, huge data analyses and precise visualizations, for example, would require parallel computations, and the parallel computing needs the parallelization techniques. In this Chapter a parallel program generation support is discussed, and a computer-assisted parallel program generation system P-NCAS is introduced. Computer assisted problem solving is one of key methods to promote innovations in science and engineering, and contributes to enrich our society and our life toward a programming-free environment in computing science. Problem solving environments (PSE) research activities had started to enhance the programming power in 1970's. The P-NCAS is one of the PSEs; The PSE concept provides an integrated human-friendly computational software and hardware system to solve a target ...

  13. Massive Variability Surveys from Venezuela

    E-Print Network [OSTI]

    Cesar Briceno

    2003-04-03T23:59:59.000Z

    At the Venezuela National Astronomical Observatory we are carrying out variability surveys spanning many hundreds of square degrees near the celestial equator, using an 8k x 8k CCD Mosaic Camera optimized for drift-scanning on a 1m Schmidt telescope. Among the initial efforts was a project to obtain the first moderately deep, homogeneous sample of young stars over an area of ~180sqr.deg. encompassing the entire Orion OB1 association, one of the nearest and most active regions of star formation. The results show that variability is a powerful technique to identify pre-main sequence populations, specially in sparse areas devoid of gas and dust. We are currently developing a massive database, equipped with web-based data mining tools, that will make our data and results available to the astronomical community.

  14. X-ray Emission from Massive Stars

    E-Print Network [OSTI]

    Cohen, David

    X-ray Emission from Massive Stars David Cohen Department of Physics and Astronomy Swarthmore #12;What is the mechanism by which massive stars produce x-rays? New results from the Chandra X-ray Observatory ­ high-resolution x-ray spectroscopy: measuring Doppler broadening in emission lines Testing

  15. Alexandru Iosup Parallel and Distributed Systems Group

    E-Print Network [OSTI]

    Iosup, Alexandru

    Engineering Center (TCE), Haifa, IL IaaS Cloud Benchmarking Massivizing Online Social Games Gamification

  16. Parallel Monte Carlo reactor neutronics

    SciTech Connect (OSTI)

    Blomquist, R.N.; Brown, F.B.

    1994-03-01T23:59:59.000Z

    The issues affecting implementation of parallel algorithms for large-scale engineering Monte Carlo neutron transport simulations are discussed. For nuclear reactor calculations, these include load balancing, recoding effort, reproducibility, domain decomposition techniques, I/O minimization, and strategies for different parallel architectures. Two codes were parallelized and tested for performance. The architectures employed include SIMD, MIMD-distributed memory, and workstation network with uneven interactive load. Speedups linear with the number of nodes were achieved.

  17. Binary Capture Rates for Massive Protostars

    E-Print Network [OSTI]

    Nickolas Moeckel; John Bally

    2007-04-09T23:59:59.000Z

    The high multiplicity of massive stars in dense, young clusters is established early in their evolution. The mechanism behind this remains unresolved. Recent results suggest that massive protostars may capture companions through disk interactions with much higher efficiency than their solar mass counterparts. However, this conclusion is based on analytic determinations of capture rates and estimates of the robustness of the resulting binaries. We present the results of coupled n-body and SPH simulations of star-disk encounters to further test the idea that disk-captured binaries contribute to the observed multiplicity of massive stars.

  18. Parallel contingency statistics with Titan.

    SciTech Connect (OSTI)

    Thompson, David C.; Pebay, Philippe Pierre

    2009-09-01T23:59:59.000Z

    This report summarizes existing statistical engines in VTK/Titan and presents the recently parallelized contingency statistics engine. It is a sequel to [PT08] and [BPRT09] which studied the parallel descriptive, correlative, multi-correlative, and principal component analysis engines. The ease of use of this new parallel engines is illustrated by the means of C++ code snippets. Furthermore, this report justifies the design of these engines with parallel scalability in mind; however, the very nature of contingency tables prevent this new engine from exhibiting optimal parallel speed-up as the aforementioned engines do. This report therefore discusses the design trade-offs we made and study performance with up to 200 processors.

  19. Massively Parallel Spectral Element Large Eddy Simulation of a Turbulent Channel Using Wall Models

    E-Print Network [OSTI]

    Rabau, Joshua I

    2013-05-01T23:59:59.000Z

    Wall-bounded turbulent flows are prevalent in engineering and industrial applications. Walls greatly affect turbulent characteristics in many ways including production and propagation of turbulent stresses. While computational fluid dynamics can...

  20. Evolution's footsteps : reconstructing in vitro and in vivo evolutionary trajectories via massively parallel sequencing and profiling

    E-Print Network [OSTI]

    Funt, Jason Michael

    2012-01-01T23:59:59.000Z

    Understanding how phenotypes evolve through natural selection is a fundamental question of biology. Microbial evolution studies provide the rare opportunity to experimentally elucidate the changes that allow an organism ...

  1. Compact Graph Representations and Parallel Connectivity Algorithms for Massive Dynamic Network Analysis

    E-Print Network [OSTI]

    Madduri, Kamesh

    2009-01-01T23:59:59.000Z

    vol. 411, pp. 41– [17] D. Kempe, J. Kleinberg, and A.net- works as de?ned by Kempe et al. [17]: a temporal

  2. Domain-specific translator and optimizer for massive on- chip parallelism

    E-Print Network [OSTI]

    Unat, Didem

    2012-01-01T23:59:59.000Z

    of the engine block and around the joints in the foot imageof the engine block and around the joints in the foot image

  3. Domain-specific translator and optimizer for massive on- chip parallelism

    E-Print Network [OSTI]

    Unat, Didem

    2012-01-01T23:59:59.000Z

    Trends in Computer Architecture . . . . . . . . . . 2.1.1E. Moore. Readings in computer architecture. cramming moreLectures on Computer Architecture. Morgan & Claypool

  4. Smith-Waterman Sequence Alignment For Massively Parallel High-Performance Computing Architectures.

    E-Print Network [OSTI]

    Steinfadt, Shannon Irene

    2010-01-01T23:59:59.000Z

    ?? This research addresses one of the most often used tools in bioinformatics, sequence alignment. The increasing growth and complexity of high-performance computing as well… (more)

  5. Massively-Parallel Spectral Element Large Eddy Simulation of a Ring-Type Gas Turbine Combustor

    E-Print Network [OSTI]

    Camp, Joshua Lane

    2012-07-16T23:59:59.000Z

    The average and fluctuating components in a model ring-type gas turbine combustor are characterized using a Large Eddy Simulation at a Reynolds number of 11,000, based on the bulk velocity and the mean channel height. A spatial filter is applied...

  6. Systematic dissection of regulatory motifs in 2000 predicted human enhancers using a massively parallel reporter assay

    E-Print Network [OSTI]

    Kheradpour, Pouya

    Genome-wide chromatin annotations have permitted the mapping of putative regulatory elements across multiple human cell types. However, their experimental dissection by directed regulatory motif disruption has remained ...

  7. Domain-specific translator and optimizer for massive on- chip parallelism

    E-Print Network [OSTI]

    Unat, Didem

    2012-01-01T23:59:59.000Z

    Grids BW-bound Constraint Solver (Solv) Finite State Machinefor the input vector. The Solv kernel is a rigid-bodytwo of the kernels Sort and Solv perform better on Core i7.

  8. Casimir Pistons for Massive Scalar Fields

    E-Print Network [OSTI]

    Xiang-hua Zhai; Yan-yan Zhang; Xin-zhou Li

    2008-08-01T23:59:59.000Z

    The Casimir force on two-dimensional pistons for massive scalar fields with both Dirichlet and hybrid boundary conditions is computed. The physical result is obtained by making use of generalized $\\zeta$-function regularization technique. The influence of the mass and the position of the piston in the force is studied graphically. The Casimir force for massive scalar field is compared to that for massless scalar field.

  9. Is Monte Carlo embarrassingly parallel?

    SciTech Connect (OSTI)

    Hoogenboom, J. E. [Delft Univ. of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Delft Nuclear Consultancy, IJsselzoom 2, 2902 LB Capelle aan den IJssel (Netherlands)

    2012-07-01T23:59:59.000Z

    Monte Carlo is often stated as being embarrassingly parallel. However, running a Monte Carlo calculation, especially a reactor criticality calculation, in parallel using tens of processors shows a serious limitation in speedup and the execution time may even increase beyond a certain number of processors. In this paper the main causes of the loss of efficiency when using many processors are analyzed using a simple Monte Carlo program for criticality. The basic mechanism for parallel execution is MPI. One of the bottlenecks turn out to be the rendez-vous points in the parallel calculation used for synchronization and exchange of data between processors. This happens at least at the end of each cycle for fission source generation in order to collect the full fission source distribution for the next cycle and to estimate the effective multiplication factor, which is not only part of the requested results, but also input to the next cycle for population control. Basic improvements to overcome this limitation are suggested and tested. Also other time losses in the parallel calculation are identified. Moreover, the threading mechanism, which allows the parallel execution of tasks based on shared memory using OpenMP, is analyzed in detail. Recommendations are given to get the maximum efficiency out of a parallel Monte Carlo calculation. (authors)

  10. Preprint of a paper to appear in Applied Optics, Vol. 33, No. 11, November 1994 A Scalable Optical Hypercubebased Interconnection Network for Massively

    E-Print Network [OSTI]

    Louri, Ahmed

    Preprint of a paper to appear in Applied Optics, Vol. 33, No. 11, November 1994 A Scalable Optical of massively parallel computers. This paper presents a new modular optical interconnection network, called an Optical Multi­Mesh Hypercube (OMMH), which is both size­ and time­scalable. The OMMH combines positive

  11. Alexandru Iosup Parallel and Distributed Systems Group

    E-Print Network [OSTI]

    Iosup, Alexandru

    Online Games: High Performance Computing and High Quality Time 1 Massivizing Social Games: High used to be art, may now be computing Massivizing Social Games: High Performance Computing and High,000,000 active players Massivizing Social Games: High Performance Computing and High Quality Time ­ A. Iosup 3

  12. Endpoint-based parallel data processing in a parallel active messaging interface of a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J; Blocksome, Michael E; Ratterman, Joseph D; Smith, Brian E

    2014-02-11T23:59:59.000Z

    Endpoint-based parallel data processing in a parallel active messaging interface ('PAMI') of a parallel computer, the PAMI composed of data communications endpoints, each endpoint including a specification of data communications parameters for a thread of execution on a compute node, including specifications of a client, a context, and a task, the compute nodes coupled for data communications through the PAMI, including establishing a data communications geometry, the geometry specifying, for tasks representing processes of execution of the parallel application, a set of endpoints that are used in collective operations of the PAMI including a plurality of endpoints for one of the tasks; receiving in endpoints of the geometry an instruction for a collective operation; and executing the instruction for a collective opeartion through the endpoints in dependence upon the geometry, including dividing data communications operations among the plurality of endpoints for one of the tasks.

  13. Endpoint-based parallel data processing in a parallel active messaging interface of a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J.; Blocksome, Michael A.; Ratterman, Joseph D.; Smith, Brian E.

    2014-08-12T23:59:59.000Z

    Endpoint-based parallel data processing in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI composed of data communications endpoints, each endpoint including a specification of data communications parameters for a thread of execution on a compute node, including specifications of a client, a context, and a task, the compute nodes coupled for data communications through the PAMI, including establishing a data communications geometry, the geometry specifying, for tasks representing processes of execution of the parallel application, a set of endpoints that are used in collective operations of the PAMI including a plurality of endpoints for one of the tasks; receiving in endpoints of the geometry an instruction for a collective operation; and executing the instruction for a collective operation through the endpoints in dependence upon the geometry, including dividing data communications operations among the plurality of endpoints for one of the tasks.

  14. SED modeling of Young Massive Stars

    E-Print Network [OSTI]

    Thomas P. Robitaille

    2007-11-27T23:59:59.000Z

    In this contribution, I review the applications and potential limitations of the spectral energy distribution fitting tool that I have developed, with a strong emphasis on the limits to which this tool can be used to improve our understanding of massive star formation. I discuss why our current grid of models cannot be used to distinguish between the several competing theories of massive star formation. I also discuss stellar mass determinations, artificial correlations between parameters in the grid of models, multiplicity, confusion, dust assumptions, and unique fits. I briefly review the improvements we intend to carry out for our next grid of models, which will eliminate many of these limitations. Finally, I show examples of applications of this tool to massive young stars.

  15. Primordial Li abundance and massive particles

    SciTech Connect (OSTI)

    Latin-Capital-Letter-Eth apo, H. [Department of Physics, Akdeniz University, TR-07058, Antalya (Turkey)

    2012-10-20T23:59:59.000Z

    The problem of the observed lithium abundance coming from the Big Bang Nucleosynthesis is as of yet unsolved. One of the proposed solutions is including relic massive particles into the Big Bang Nucleosynthesis. We investigated the effects of such particles on {sup 4}HeX{sup -}+{sup 2}H{yields}{sup 6}Li+X{sup -}, where the X{sup -} is the negatively charged massive particle. We demonstrate the dominance of long-range part of the potential on the cross-section.

  16. New Candidate Massive Clusters from 2MASS

    E-Print Network [OSTI]

    Froebrich, D

    2013-01-01T23:59:59.000Z

    Massive stars are important for the evolution of the interstellar medium. The detailed study of their properties (such as mass loss, rotation, magnetic fields) is enormously facilitated by samples of these objects in young massive galactic star clusters. Using 2MASS we have searched for so far unknown candidates of red supergiant clusters along the Galactic Plane. Utilising deep high resolution UKIDSS GPS and VISTA VVV data to study colour-magnitude diagrams, we uncover six new massive cluster candidates in the inner Galaxy. If spectroscopically confirmed as real clusters, two of them could be part of the Scutum-Complex. One cluster candidate has a number of potential red supergiant members comparable to RSGC1 and 3. Our investigation of UKIDSS data reveals for the first time the main sequence of the massive cluster RSGC2. The stars of the sequence show an increased projected density at the same position as the known red supergiants in the cluster and have E(J-K)=1.6mag. This either indicates an unusual extin...

  17. The Tunnel Vision Syndrome: Massively Delaying Progress

    E-Print Network [OSTI]

    Hartenstein, Reiner

    The Tunnel Vision Syndrome: Massively Delaying Progress Reiner Hartenstein, Professor, IEEE fellow facet as the complete answer are far from solving the problem. What is the reason of these slow-down- stream-based computing was delayed for decades by the tunnel vision syndrome. The History of Systolic

  18. Beta Functions of Topologically Massive Supergravity

    E-Print Network [OSTI]

    R. Percacci; M. J. Perry; C. N. Pope; E. Sezgin

    2013-02-20T23:59:59.000Z

    We compute the one-loop beta functions of the cosmological constant, Newton's constant and the topological mass in topologically massive supergravity in three dimensions. We use a variant of the proper time method supplemented by a simple choice of cutoff function. We find that the dimensionless coefficient of the Chern-Simons term, $\

  19. Is the Human Mind Massively Modular?

    E-Print Network [OSTI]

    Samuels, Richard

    CHAPTER T H R E E Is the Human Mind Massively Modular? Richard Samuels Introduction: Minds as Mechanisms Among the most pervasive and fundamental assumptions in cognitive science is that the human mind (or mind-brain) is a mechanism of some sort: a physical device com- posed of functionally specifiable

  20. Standard Templates Adaptive Parallel Library

    E-Print Network [OSTI]

    Arzu, Francisco Jose

    2000-01-01T23:59:59.000Z

    ]. STAPL &s v, nuen m a simple extension of the C++ hingu. & e f1. 4f which prov&dcs a SPMD motlel of' parallelism that maps easily onto distnbuted sharcd- memory sys&ems (e. g, HP V-class, SGI Power Challenge o& networks of workstations using Tread... () uses the schcduler to dispatch the per-processor segments of the container to the processors. Figure 2 show the relations between the STAPL components. 2. 2 Related %'ork 2. 2. 1 Parallel Standard Template I. ibrary The HPC+ i consortium h...

  1. Parallel continuation-based global optimization for molecular conformation and protein folding

    SciTech Connect (OSTI)

    Coleman, T.F.; Wu, Z. [Cornell Univ., Ithaca, NY (United States)

    1994-12-31T23:59:59.000Z

    This paper presents the authors` recent work on developing parallel algorithms and software for solving the global minimization problem for molecular conformation, especially protein folding. Global minimization problems are difficult to solve when the objective functions have many local minimizers, such as the energy functions for protein folding. In their approach, to avoid directly minimizing a ``difficult`` function, a special integral transformation is introduced to transform the function into a class of gradually deformed, but ``smoother`` or ``easier`` functions. An optimization procedure is then applied to the new functions successively, to trace their solutions back to the original function. The method can be applied to a large class of nonlinear partially separable functions including energy functions for molecular conformation and protein folding. Mathematical theory for the method, as a special continuation approach to global optimization, is established. Algorithms with different solution tracing strategies are developed. Different levels of parallelism are exploited for the implementation of the algorithms on massively parallel architectures.

  2. Architecture, implementation and parallelization of the software to search for periodic gravitational wave signals

    E-Print Network [OSTI]

    Gevorg Poghosyan; Sanchit Matta; Achim Streit; Micha? Bejger; Andrzej Królak

    2014-10-14T23:59:59.000Z

    The parallelization, design and scalability of the \\sky code to search for periodic gravitational waves from rotating neutron stars is discussed. The code is based on an efficient implementation of the F-statistic using the Fast Fourier Transform algorithm. To perform an analysis of data from the advanced LIGO and Virgo gravitational wave detectors' network, which will start operating in 2015, hundreds of millions of CPU hours will be required - the code utilizing the potential of massively parallel supercomputers is therefore mandatory. We have parallelized the code using the Message Passing Interface standard, implemented a mechanism for combining the searches at different sky-positions and frequency bands into one extremely scalable program. The parallel I/O interface is used to escape bottlenecks, when writing the generated data into file system. This allowed to develop a highly scalable computation code, which would enable the data analysis at large scales on acceptable time scales. Benchmarking of the code on a Cray XE6 system was performed to show efficiency of our parallelization concept and to demonstrate scaling up to 50 thousand cores in parallel.

  3. Tutorial: Parallel Simulation on Supercomputers

    SciTech Connect (OSTI)

    Perumalla, Kalyan S [ORNL

    2012-01-01T23:59:59.000Z

    This tutorial introduces typical hardware and software characteristics of extant and emerging supercomputing platforms, and presents issues and solutions in executing large-scale parallel discrete event simulation scenarios on such high performance computing systems. Covered topics include synchronization, model organization, example applications, and observed performance from illustrative large-scale runs.

  4. Implicit Parallelism Alden H. Wright

    E-Print Network [OSTI]

    Rowe, Jon

    Implicit Parallelism Alden H. Wright , Michael D. Vose ¡ , and Jonathan E. Rowe ¢ £ Dept. of Computer Science, University of Montana, Missoula, Montana 59812, USA wright@cs.umt.edu¤ Computer Science family of schemata. [Vose and Wright, 2001] showed that each schema corresponds to a vector in pop

  5. One Loop Beta Functions in Topologically Massive Gravity

    E-Print Network [OSTI]

    R. Percacci; E. Sezgin

    2010-02-15T23:59:59.000Z

    We calculate the running of the three coupling constants in cosmological, topologically massive 3d gravity. We find that \

  6. Unveiling the Formation of Massive Galaxies

    E-Print Network [OSTI]

    Christopher J. Conselice

    2004-04-21T23:59:59.000Z

    Massive galaxies, such as nearby ellipticals, have relatively low number densities, yet they host the majority of the stellar mass in the universe. Understanding their origin is a central problem of galaxy formation. Age dating of stellar populations found in modern ellipticals, and observations of star formation in high redshift galaxies, allow us to determine roughly when these systems formed. These age diagnostics however do not tell us what triggered star formation, or how galaxies form as opposed to simply when. Recent analyses of the structures of z > 2 ultraviolet selected galaxies reveal that major galaxy mergers are a likely method for forming some massive galaxies. There are however galaxy populations at high redshift (z > 2), namely infrared and sub-millimeter bright systems, whose evolutionary relationship to modern ellipticals is still uncertain. An improved characterization of these and other high redshift galaxy populations is achievable with large infrared imaging and spectroscopic surveys.

  7. Visser's massive graviton bimetric theory revisited

    SciTech Connect (OSTI)

    Roany, Alain de; Chauvineau, Bertrand; Freitas Pacheco, Jose A. de [University of Nice-Sophia Antipolis, Observatoire de la Cote d'Azur, Laboratoire Cassiopee, BP 4229, Nice Cedex 4 (France)

    2011-10-15T23:59:59.000Z

    A massive gravity theory was proposed by Visser in the late 1990s. This theory, based on a background metric b{sub {alpha}{beta}} and on an usual dynamical metric g{sub {alpha}{beta}} has the advantage of being free of ghosts as well as discontinuities present in other massive theories proposed in the past. In the present investigation, the equations of Visser's theory are revisited with particular care on the related conservation laws. It will be shown that a multiplicative factor is missing in the graviton tensor originally derived by Visser, which has no incidence on the weak field approach but becomes important in the strong field regime when, for instance, cosmological applications are considered. In this case, contrary to some previous claims found in the literature, we conclude that a nonstatic background metric is required in order to obtain a solution able to mimic the {Lambda}CDM cosmology.

  8. More on massive 3D gravity

    SciTech Connect (OSTI)

    Bergshoeff, Eric A.; Hohm, Olaf [Centre for Theoretical Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Townsend, Paul K. [Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)

    2009-06-15T23:59:59.000Z

    We explore the space of static solutions of the recently discovered three-dimensional 'new massive gravity' (NMG), allowing for either sign of the Einstein-Hilbert term and a cosmological term parametrized by a dimensionless constant {lambda}. For {lambda}=-1 we find black hole solutions asymptotic (but not isometric) to the unique (anti) de Sitter [(A)dS] vacuum, including extremal black holes that interpolate between this vacuum and (A)dS{sub 2}xS{sup 1}. We also investigate unitarity of linearized NMG in (A)dS vacua. We find unitary theories for some dS vacua, but (bulk) unitarity in AdS implies negative central charge of the dual conformal field theories (CFT), except for {lambda}=3 where the central charge vanishes and the bulk gravitons are replaced by 'massive photons'. A similar phenomenon is found in the massless limit of NMG, for which the linearized equations become equivalent to Maxwell's equations.

  9. Massive Nonplanar Two-Loop Maximal Unitarity

    E-Print Network [OSTI]

    Mads Sogaard; Yang Zhang

    2014-06-19T23:59:59.000Z

    We explore maximal unitarity for nonplanar two-loop integrals with up to four massive external legs. In this framework, the amplitude is reduced to a basis of master integrals whose coefficients are extracted from maximal cuts. The hepta-cut of the nonplanar double box defines a nodal algebraic curve associated with a multiply pinched genus-3 Riemann surface. All possible configurations of external masses are covered by two distinct topological pictures in which the curve decomposes into either six or eight Riemann spheres. The procedure relies on consistency equations based on vanishing of integrals of total derivatives and Levi-Civita contractions. Our analysis indicates that these constraints are governed by the global structure of the maximal cut. Lastly, we present an algorithm for computing generalized cuts of massive integrals with higher powers of propagators based on the Bezoutian matrix method.

  10. Harmonic polylogarithms for massive Bhabha scattering

    E-Print Network [OSTI]

    M. Czakon; J. Gluza; T. Riemann

    2005-08-19T23:59:59.000Z

    One- and two-dimensional harmonic polylogarithms, HPLs and GPLs, appear in calculations of multi-loop integrals. We discuss them in the context of analytical solutions for two-loop master integrals in the case of massive Bhabha scattering in QED. For the GPLs we discuss analytical representations, conformal transformations, and also their transformations corresponding to relations between master integrals in the s- and t-channel.

  11. Bigravity and Lorentz-violating massive gravity

    SciTech Connect (OSTI)

    Blas, D.; Garriga, J. [ICC, Departament de Fisica Fonamental, Universitat de Barcelona, Diagonal 647, 08028 Barcelona (Spain); Deffayet, C. [APC, Batiment Condorcet, 10 rue Alice Domont et Leonie Duquet, 75205 Paris Cedex 13 (France); GReCO/IAP, 98 bis Boulevard Arago, 75014 Paris (France)

    2007-11-15T23:59:59.000Z

    Bigravity is a natural arena where a nonlinear theory of massive gravity can be formulated. If the interaction between the metrics f and g is nonderivative, spherically symmetric exact solutions can be found. At large distances from the origin, these are generically Lorentz-breaking bi-flat solutions (provided that the corresponding vacuum energies are adjusted appropriately). The spectrum of linearized perturbations around such backgrounds contains a massless as well as a massive graviton, with two physical polarizations each. There are no propagating vectors or scalars, and the theory is ghost free (as happens with certain massive gravities with explicit breaking of Lorentz invariance). At the linearized level, corrections to general relativity are proportional to the square of the graviton mass, and so there is no van Dam-Veltam-Zakharov discontinuity. Surprisingly, the solution of linear theory for a static spherically symmetric source does not agree with the linearization of any of the known exact solutions. The latter coincide with the standard Schwarzschild-(anti)-de Sitter solutions of general relativity, with no corrections at all. Another interesting class of solutions is obtained where f and g are proportional to each other. The case of bi-de Sitter solutions is analyzed in some detail.

  12. Hyper-Systolic Parallel Computing

    E-Print Network [OSTI]

    Th. Lippert; A. Seyfried; A. Bode; K. Schilling

    1995-07-25T23:59:59.000Z

    A new class of parallel algorithms is introduced that can achieve a complexity of O(n^3/2) with respect to the interprocessor communication, in the exact computation of systems with pairwise mutual interactions of all elements. Hitherto, conventional methods exhibit a communicational complexity of O(n^2). The amount of computation operations is not altered for the new algorithm which can be formulated as a kind of h-range problem, known from the mathematical field of Additive Number Theory. We will demonstrate the reduction in communicational expense by comparing the standard-systolic algorithm and the new algorithm on the connection machine CM5 and the CRAY T3D. The parallel method can be useful in various scientific and engineering fields like exact n-body dynamics with long range forces, polymer chains, protein folding or signal processing.

  13. A Parallel Graph Partitioner for STAPL

    E-Print Network [OSTI]

    Castet, Nicolas

    2013-04-26T23:59:59.000Z

    difficult task for programmers. They need to deal with low-level parallel mechanisms such as data distribution, inter-processor communication, and task placement. The goal of the Standard Template Adaptive Parallel Library (STAPL) is to provide a generic...

  14. A Parallel Geometric Multifrontal Solver Using Hierarchically ...

    E-Print Network [OSTI]

    2014-07-17T23:59:59.000Z

    In particular, we demonstrate how to manage two layers of tree parallelism that integrates ... allelism within the outer multifrontal tree parallelism, and how the rank properties behave and benefit the ...... Ph.D. Dissertation. Institut National ...

  15. On-the-fly pipeline parallelism

    E-Print Network [OSTI]

    Lee, I-Ting Angelina

    Pipeline parallelism organizes a parallel program as a linear sequence of s stages. Each stage processes elements of a data stream, passing each processed data element to the next stage, and then taking on a new element ...

  16. Feedback-optimized parallel tempering Monte Carlo

    E-Print Network [OSTI]

    Katzgraber, H G; Trebst, S; Huse, D A; Troyer, M

    2006-01-01T23:59:59.000Z

    brie?y discuss possible feedback schemes for systems that1742-5468/06/P03018+22$30.00 Feedback-optimized parallel5468/2006/03/P03018 Feedback-optimized parallel tempering

  17. Parallel Repetition of Entangled Games

    E-Print Network [OSTI]

    Julia Kempe; Thomas Vidick

    2011-05-11T23:59:59.000Z

    We consider one-round games between a classical referee and two players. One of the main questions in this area is the parallel repetition question: Is there a way to decrease the maximum winning probability of a game without increasing the number of rounds or the number of players? Classically, efforts to resolve this question, open for many years, have culminated in Raz's celebrated parallel repetition theorem on one hand, and in efficient product testers for PCPs on the other. In the case where players share entanglement, the only previously known results are for special cases of games, and are based on techniques that seem inherently limited. Here we show for the first time that the maximum success probability of entangled games can be reduced through parallel repetition, provided it was not initially 1. Our proof is inspired by a seminal result of Feige and Kilian in the context of classical two-prover one-round interactive proofs. One of the main components in our proof is an orthogonalization lemma for operators, which might be of independent interest.

  18. Optimization Online - A PARALLEL interior point decomposition ...

    E-Print Network [OSTI]

    Kartik Krishnan Sivaramakrishnan

    2006-12-04T23:59:59.000Z

    Dec 4, 2006 ... ... and decomposed and distributed subproblems (smaller SDPs) in a parallel and distributed high performance computing environment.

  19. Alexandru Iosup Parallel and Distributed Systems Group

    E-Print Network [OSTI]

    Iosup, Alexandru

    Online Games: High Performance Computing and High Quality Time 1 Massivizing Social Games: High,000,000 active players Massivizing Social Games: High Performance Computing and High Quality Time ­ A. Iosup 3 Games: High Performance Computing and High Quality Time ­ A. Iosup 4 Sources: MMOGChart, own research

  20. Nonlinear parameter estimation in parallel computing environments

    E-Print Network [OSTI]

    Li, Jie

    1996-01-01T23:59:59.000Z

    to solve these issues with respect to PEST. We then propose a hierarchical parallel control structure for PEST based on the manager-worker parallel programming model. We also discuss in detail the implementation of the parallel version of PEST in an Intel...

  1. Holographic renormalization of new massive gravity

    SciTech Connect (OSTI)

    Alishahiha, Mohsen [School of Physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Naseh, Ali [School of Physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran (Iran, Islamic Republic of)

    2010-11-15T23:59:59.000Z

    We study holographic renormalization for three-dimensional new massive gravity. By studying the general falloff conditions for the metric allowed by the model at infinity, we show that at the critical point where the central charges of the dual conformal field theory (CFT) are zero, it contains a leading logarithmic behavior. In the context of AdS/CFT correspondence it can be identified as a source for an irrelevant operator in the dual CFT. The presence of the logarithmic falloff may be interpreted as the fact that the dual CFT would be a logarithmic conformal field theory.

  2. Holographic superconductors from the massive gravity

    E-Print Network [OSTI]

    Hua Bi Zeng; Jian-Pin Wu

    2014-09-24T23:59:59.000Z

    A holographic superconductor is constructed in the background of a massive gravity theory. In the normal state without condensation, the conductivity exhibits a Drude peak that approaches a delta function in the massless gravity limit as studied by David Vegh. In the superconducting state, besides the infinite DC conductivity, the AC conductivity has Drude behavior at low frequency followed by a power law-fall. These results are in agreement with that found earlier by Horowitz and Santos, who studied a holographic superconductor with an implicit periodic potential beyond the probe limit. The results also agree with measurements on some cuprates.

  3. Casimir Effect of Scalar Massive Field

    E-Print Network [OSTI]

    Sonia Mobassem

    2014-06-03T23:59:59.000Z

    The energy momentum tensor is used to introduce the Casimir force of the massive scalar field acting on a nonpenetrating surface. This expression can be used to evaluate the vacuum force by employing the appropriate field operators. To simplify our formalism we also relates the vacuum force expression to the imaginary part of the Green function via the fluctuation dissipation theorem and Kubo formula. This allows one to evaluate the vacuum force without resorting to the process of field quantization. These two approaches are used to calculate the attractive force between two nonpenetrating plates. Special attention is paid to the generalization of the formalism to D + 1 space-time dimensions.

  4. Transport coefficients of a massive pion gas

    E-Print Network [OSTI]

    D. Fernandez-Fraile; A. Gomez Nicola

    2009-12-20T23:59:59.000Z

    We review or main results concerning the transport coefficients of a light meson gas, in particular we focus on the case of a massive pion gas. Leading order results according to the chiral power-counting are presented for the DC electrical conductivity, thermal conductivity, shear viscosity, and bulk viscosity. We also comment on the possible correlation between the bulk viscosity and the trace anomaly in QCD, as well as the relation between unitarity and a minimum of the quotient $\\eta/s$ near the phase transition.

  5. A Massive Stellar Burst Before the Supernova

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary)morphinanInformation Desert SouthwestTechnologies |November 2011A First Look at YeastMES- HelpingMUONA Massive

  6. A parallel algorithm for transient solid dynamics simulations with contact detection

    SciTech Connect (OSTI)

    Attaway, S.; Hendrickson, B.; Plimpton, S.; Gardner, D.; Vaughan, C.; Heinstein, M.; Peery, J.

    1996-06-01T23:59:59.000Z

    Solid dynamics simulations with Lagrangian finite elements are used to model a wide variety of problems, such as the calculation of impact damage to shipping containers for nuclear waste and the analysis of vehicular crashes. Using parallel computers for these simulations has been hindered by the difficulty of searching efficiently for material surface contacts in parallel. A new parallel algorithm for calculation of arbitrary material contacts in finite element simulations has been developed and implemented in the PRONTO3D transient solid dynamics code. This paper will explore some of the issues involved in developing efficient, portable, parallel finite element models for nonlinear transient solid dynamics simulations. The contact-detection problem poses interesting challenges for efficient implementation of a solid dynamics simulation on a parallel computer. The finite element mesh is typically partitioned so that each processor owns a localized region of the finite element mesh. This mesh partitioning is optimal for the finite element portion of the calculation since each processor must communicate only with the few connected neighboring processors that share boundaries with the decomposed mesh. However, contacts can occur between surfaces that may be owned by any two arbitrary processors. Hence, a global search across all processors is required at every time step to search for these contacts. Load-imbalance can become a problem since the finite element decomposition divides the volumetric mesh evenly across processors but typically leaves the surface elements unevenly distributed. In practice, these complications have been limiting factors in the performance and scalability of transient solid dynamics on massively parallel computers. In this paper the authors present a new parallel algorithm for contact detection that overcomes many of these limitations.

  7. Xyce parallel electronic simulator design.

    SciTech Connect (OSTI)

    Thornquist, Heidi K.; Rankin, Eric Lamont; Mei, Ting; Schiek, Richard Louis; Keiter, Eric Richard; Russo, Thomas V.

    2010-09-01T23:59:59.000Z

    This document is the Xyce Circuit Simulator developer guide. Xyce has been designed from the 'ground up' to be a SPICE-compatible, distributed memory parallel circuit simulator. While it is in many respects a research code, Xyce is intended to be a production simulator. As such, having software quality engineering (SQE) procedures in place to insure a high level of code quality and robustness are essential. Version control, issue tracking customer support, C++ style guildlines and the Xyce release process are all described. The Xyce Parallel Electronic Simulator has been under development at Sandia since 1999. Historically, Xyce has mostly been funded by ASC, the original focus of Xyce development has primarily been related to circuits for nuclear weapons. However, this has not been the only focus and it is expected that the project will diversify. Like many ASC projects, Xyce is a group development effort, which involves a number of researchers, engineers, scientists, mathmaticians and computer scientists. In addition to diversity of background, it is to be expected on long term projects for there to be a certain amount of staff turnover, as people move on to different projects. As a result, it is very important that the project maintain high software quality standards. The point of this document is to formally document a number of the software quality practices followed by the Xyce team in one place. Also, it is hoped that this document will be a good source of information for new developers.

  8. METHYL CYANIDE OBSERVATIONS TOWARD MASSIVE PROTOSTARS

    SciTech Connect (OSTI)

    Rosero, V.; Hofner, P. [Physics Department, New Mexico Tech, 801 Leroy Place, Socorro, NM 87801 (United States); Kurtz, S. [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, Morelia 58090 (Mexico); Bieging, J. [Department of Astronomy and Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Araya, E. D. [Physics Department, Western Illinois University, 1 University Circle, Macomb, IL 61455 (United States)

    2013-07-01T23:59:59.000Z

    We report the results of a survey in the CH{sub 3}CN J = 12 {yields} 11 transition toward a sample of massive proto-stellar candidates. The observations were carried out with the 10 m Submillimeter Telescope on Mount Graham, AZ. We detected this molecular line in 9 out of 21 observed sources. In six cases this is the first detection of this transition. We also obtained full beam sampled cross-scans for five sources which show that the lower K-components can be extended on the arcminute angular scale. The higher K-components, however, are always found to be compact with respect to our 36'' beam. A Boltzmann population diagram analysis of the central spectra indicates CH{sub 3}CN column densities of about 10{sup 14} cm{sup -2}, and rotational temperatures above 50 K, which confirms these sources as hot molecular cores. Independent fits to line velocity and width for the individual K-components resulted in the detection of an increasing blueshift with increasing line excitation for four sources. Comparison with mid-infrared (mid-IR) images from the SPITZER GLIMPSE/IRAC archive for six sources show that the CH{sub 3}CN emission is generally coincident with a bright mid-IR source. Our data clearly show that the CH{sub 3}CN J = 12 {yields} 11 transition is a good probe of the hot molecular gas near massive protostars, and provide the basis for future interferometric studies.

  9. Parallel FE Approximation of the Even/Odd Parity Form of the Linear Boltzmann Equation

    SciTech Connect (OSTI)

    Drumm, Clifton R.; Lorenz, Jens

    1999-07-21T23:59:59.000Z

    A novel solution method has been developed to solve the linear Boltzmann equation on an unstructured triangular mesh. Instead of tackling the first-order form of the equation, this approach is based on the even/odd-parity form in conjunction with the conventional mdtigroup discrete-ordinates approximation. The finite element method is used to treat the spatial dependence. The solution method is unique in that the space-direction dependence is solved simultaneously, eliminating the need for the conventional inner iterations, and the method is well suited for massively parallel computers.

  10. Feedback Processes [in Massive Star Formation]: A Theoretical Perspective

    E-Print Network [OSTI]

    Mordecai-Mark Mac Low

    2007-11-26T23:59:59.000Z

    I review the evidence for the importance of feedback from massive stars at small and large scales. The feedback mechanisms include accretion luminosity, ionizing radiation, collimated outflows, and stellar winds. The good news is that feedback doesn't entirely prevent the formation of massive stars, while the bad news is that we don't know what does limit their masses. Feedback from massive stars also influences their surroundings. I argue that this does not produce a triggering efficiency above unity, nor does it prevent lots of prompt star formation in GMCs, though it may preserve massive remnants of the clouds for many dynamical times.

  11. Studies of parallel algorithms for the solution of a Fokker-Planck equation

    SciTech Connect (OSTI)

    Deck, D. [Los Alamos National Lab., NM (United States); Samba, G. [CEA/CEL-V, Villeneuve St. Georges (France). Dept. de Mathematiques Appliquees

    1995-11-01T23:59:59.000Z

    The study of laser-created plasmas often requires the use of a kinetic model rather than a hydrodynamic one. This model change occurs, for example, in the hot spot formation in an ICF experiment or during the relaxation of colliding plasmas. When the gradients scalelengths or the size of a given system are not small compared to the characteristic mean-free-path, we have to deal with non-equilibrium situations, which can be described by the distribution functions of every species in the system. We present here a numerical method in plane or spherical 1-D geometry, for the solution of a Fokker-Planck equation that describes the evolution of stich functions in the phase space. The size and the time scale of kinetic simulations require the use of Massively Parallel Computers (MPP). We have adopted a message-passing strategy using Parallel Virtual Machine (PVM).

  12. DETECTING MASSIVE GRAVITONS USING PULSAR TIMING ARRAYS

    SciTech Connect (OSTI)

    Lee, Kejia; Kramer, Michael [University of Manchester, School of Physics and Astronomy, Jodrell Bank Centre for Astrophysics, Alan Turing Building, Manchester M13 9PL (United Kingdom); Jenet, Fredrick A.; Price, Richard H. [Department of Physics and Astronomy, University of Texas at Brownsville, Brownsville, TX 78520 (United States); Wex, Norbert, E-mail: kjlee@mpifr-bonn.mpg.d [Max-Planck-Institut fuer Radioastronomie, Bonn 53121 (Germany)

    2010-10-20T23:59:59.000Z

    At the limit of weak static fields, general relativity becomes Newtonian gravity with a potential field that falls off as inverse distance rather than a theory of Yukawa-type fields with a finite range. General relativity also predicts that the speed of disturbances of its waves is c, the vacuum light speed, and is non-dispersive. For these reasons, the graviton, the boson for general relativity, can be considered to be massless. Massive gravitons, however, are features of some alternatives to general relativity. This has motivated experiments and observations that, so far, have been consistent with the zero-mass graviton of general relativity, but further tests will be valuable. A basis for new tests may be the high sensitivity gravitational wave (GW) experiments that are now being performed and the higher sensitivity experiments that are being planned. In these experiments, it should be feasible to detect low levels of dispersion due to non-zero graviton mass. One of the most promising techniques for such a detection may be the pulsar timing program that is sensitive to nano-Hertz GWs. Here, we present some details of such a detection scheme. The pulsar timing response to a GW background with the massive graviton is calculated, and the algorithm to detect the massive graviton is presented. We conclude that, with 90% probability, massless gravitons can be distinguished from gravitons heavier than 3 x 10{sup -22} eV (Compton wavelength {lambda}{sub g} = 4.1 x 10{sup 12} km), if bi-weekly observation of 60 pulsars is performed for 5 years with a pulsar rms timing accuracy of 100 ns. If 60 pulsars are observed for 10 years with the same accuracy, the detectable graviton mass is reduced to 5 x 10{sup -23} eV ({lambda}{sub g} = 2.5 x 10{sup 13} km); for 5 year observations of 100 or 300 pulsars, the sensitivity is respectively 2.5 x 10{sup -22} ({lambda}{sub g} = 5.0 x 10{sup 12} km) and 10{sup -22} eV ({lambda}{sub g} = 1.2 x 10{sup 13} km). Finally, a 10 year observation of 300 pulsars with 100 ns timing accuracy would probe graviton masses down to 3 x 10{sup -23} eV ({lambda}{sub g} = 4.1 x 10{sup 13} km).

  13. Information hiding in parallel programs

    SciTech Connect (OSTI)

    Foster, I.

    1992-01-30T23:59:59.000Z

    A fundamental principle in program design is to isolate difficult or changeable design decisions. Application of this principle to parallel programs requires identification of decisions that are difficult or subject to change, and the development of techniques for hiding these decisions. We experiment with three complex applications, and identify mapping, communication, and scheduling as areas in which decisions are particularly problematic. We develop computational abstractions that hide such decisions, and show that these abstractions can be used to develop elegant solutions to programming problems. In particular, they allow us to encode common structures, such as transforms, reductions, and meshes, as software cells and templates that can reused in different applications. An important characteristic of these structures is that they do not incorporate mapping, communication, or scheduling decisions: these aspects of the design are specified separately, when composing existing structures to form applications. This separation of concerns allows the same cells and templates to be reused in different contexts.

  14. Cost hierarchies for abstract parallel machines

    E-Print Network [OSTI]

    O'Donnell, J.T.

    O'Donnell,J.T. Rauber,T. Ruenger,G. 13th International Workshop on Languages and Compilers for Parallel Computing (LCPC 2000) LNCS, Springer

  15. A Parallel Inertial Proximal Optimization Method

    E-Print Network [OSTI]

    2011-07-01T23:59:59.000Z

    The Douglas-Rachford algorithm is a popular iterative method for finding a zero of a ... algorithm, parallel proximal algorithms are proposed to minimize over a ...

  16. Parallel auto-correlative statistics with VTK.

    SciTech Connect (OSTI)

    Pebay, Philippe Pierre [Kitware, France; Bennett, Janine Camille

    2013-08-01T23:59:59.000Z

    This report summarizes existing statistical engines in VTK and presents both the serial and parallel auto-correlative statistics engines. It is a sequel to [PT08, BPRT09b, PT09, BPT09, PT10] which studied the parallel descriptive, correlative, multi-correlative, principal component analysis, contingency, k-means, and order statistics engines. The ease of use of the new parallel auto-correlative statistics engine is illustrated by the means of C++ code snippets and algorithm verification is provided. This report justifies the design of the statistics engines with parallel scalability in mind, and provides scalability and speed-up analysis results for the autocorrelative statistics engine.

  17. Revisiting Parallel Algorithms for Block Tridiagonal Systems...

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

    variety of scientific and engineering applications, including oceanography, computer graphics, plasma physics, iterative solvers, and many more. Parallel solvers for such systems...

  18. Parallel Processing Letters World Scientific Publishing Company

    E-Print Network [OSTI]

    Miller, Russ

    Parallel Processing Letters © World Scientific Publishing Company THE OPERATIONS DASHBOARD essential operational services, it is imperative that grid administrators can troubleshoot the problems

  19. Massive Disks in Low Surface Brightness Galaxies

    E-Print Network [OSTI]

    B. Fuchs

    2002-09-09T23:59:59.000Z

    An update of the set of low surface brightness galaxies is presented which can be used to set constraints on the otherwise ambiguous decompositions of their rotation curves into contributions due to the various components of the galaxies. The selected galaxies show all clear spiral structure and arguments of density wave theory of galactic spiral arms are used to estimate the masses of the galactic disks. Again these estimates seem to indicate that the disks of low surface brightness galaxies might be much more massive than currently thought. This puzzling result contradicts stellar population synthesis models. This would mean also that low surface brightness galaxies are not dominated by dark matter in their inner parts.

  20. Progress in the physics of massive neutrinos

    E-Print Network [OSTI]

    V. Barger; D. Marfatia; K. Whisnant

    2003-09-16T23:59:59.000Z

    The current status of the physics of massive neutrinos is reviewed with a forward-looking emphasis. The article begins with the general phenomenology of neutrino oscillations in vacuum and matter and documents the experimental evidence for oscillations of solar, reactor, atmospheric and accelerator neutrinos. Both active and sterile oscillation possibilities are considered. The impact of cosmology (BBN, CMB, leptogenesis) and astrophysics (supernovae, highest energy cosmic rays) on neutrino observables and vice versa, is evaluated. The predictions of grand unified, radiative and other models of neutrino mass are discussed. Ways of determining the unknown parameters of three-neutrino oscillations are assessed, taking into account eight-fold degeneracies in parameters that yield the same oscillation probabilities, as well as ways to determine the absolute neutrino mass scale (from beta-decay, neutrinoless double-beta decay, large scale structure and Z-bursts). Critical unknowns at present are the amplitude of \

  1. New approach for the solution of optimal control problems on parallel machines. Doctoral thesis

    SciTech Connect (OSTI)

    Stech, D.J.

    1990-01-01T23:59:59.000Z

    This thesis develops a highly parallel solution method for nonlinear optimal control problems. Balakrishnan's epsilon method is used in conjunction with the Rayleigh-Ritz method to convert the dynamic optimization of the optimal control problem into a static optimization problem. Walsh functions and orthogonal polynomials are used as basis functions to implement the Rayleigh-Ritz method. The resulting static optimization problem is solved using matrix operations which have well defined massively parallel solution methods. To demonstrate the method, a variety of nonlinear optimal control problems are solved. The nonlinear Raleigh problem with quadratic cost and nonlinear van der Pol problem with quadratic cost and terminal constraints on the states are solved in both serial and parallel on an eight processor Intel Hypercube. The solutions using both Walsh functions and Legendre polynomials as basis functions are given. In addition to these problems which are solved in parallel, a more complex nonlinear minimum time optimal control problem and nonlinear optimal control problem with an inequality constraint on the control are solved. Results show the method converges quickly, even from relatively poor initial guesses for the nominal trajectories.

  2. Graphene-enabled Wireless Communication for Massive Multicore Architectures

    E-Print Network [OSTI]

    Cabellos-Aparicio, Albert

    Graphene-enabled Wireless Communication for Massive Multicore Architectures Sergi Abadal, Eduard. This goal is feasible by using graphene-based planar antennas, which can radiate signals at the Terahertz, this is the first work that discusses the utilization of graphene-enabled wireless communication for massive

  3. LIMITING ACCRETION ONTO MASSIVE STARS BY FRAGMENTATION-INDUCED STARVATION

    SciTech Connect (OSTI)

    Peters, Thomas; Klessen, Ralf S.; Banerjee, Robi [Institut fuer Theoretische Astrophysik, Zentrum fuer Astronomie der Universitaet Heidelberg, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Low, Mordecai-Mark Mac, E-mail: thomas.peters@ita.uni-heidelberg.d [Department of Astrophysics, American Museum of Natural History, 79th Street at Central Park West, New York, NY 10024-5192 (United States)

    2010-12-10T23:59:59.000Z

    Massive stars influence their surroundings through radiation, winds, and supernova explosions far out of proportion to their small numbers. However, the physical processes that initiate and govern the birth of massive stars remain poorly understood. Two widely discussed models are monolithic collapse of molecular cloud cores and competitive accretion. To learn more about massive star formation, we perform and analyze simulations of the collapse of rotating, massive, cloud cores including radiative heating by both non-ionizing and ionizing radiation using the FLASH adaptive-mesh refinement code. These simulations show fragmentation from gravitational instability in the enormously dense accretion flows required to build up massive stars. Secondary stars form rapidly in these flows and accrete mass that would have otherwise been consumed by the massive star in the center, in a process that we term fragmentation-induced starvation. This explains why massive stars are usually found as members of high-order stellar systems that themselves belong to large clusters containing stars of all masses. The radiative heating does not prevent fragmentation, but does lead to a higher Jeans mass, resulting in fewer and more massive stars than would form without the heating. This mechanism reproduces the observed relation between the total stellar mass in the cluster and the mass of the largest star. It predicts strong clumping and filamentary structure in the center of collapsing cores, as has recently been observed. We speculate that a similar mechanism will act during primordial star formation.

  4. Hypervelocity binary stars: smoking gun of massive binary black holes

    E-Print Network [OSTI]

    Youjun Lu; Qingjuan Yu; D. N. C. Lin

    2007-07-22T23:59:59.000Z

    The hypervelocity stars recently found in the Galactic halo are expelled from the Galactic center through interactions between binary stars and the central massive black hole or between single stars and a hypothetical massive binary black hole. In this paper, we demonstrate that binary stars can be ejected out of the Galactic center with velocities up to 10^3 km/s, while preserving their integrity, through interactions with a massive binary black hole. Binary stars are unlikely to attain such high velocities via scattering by a single massive black hole or through any other mechanisms. Based on the above theoretical prediction, we propose a search for binary systems among the hypervelocity stars. Discovery of hypervelocity binary stars, even one, is a definitive evidence of the existence of a massive binary black hole in the Galactic center.

  5. Parallel MATLAB: Single Program Multiple Data

    E-Print Network [OSTI]

    Crawford, T. Daniel

    Parallel MATLAB: Single Program Multiple Data John Burkardt (FSU) Gene Cliff (AOE/ICAM - ecliff Research Computing ICAM: Interdisciplinary Center for Applied Mathematics 1 / 67 #12;MATLAB Parallel MATLAB sets up one special agent called the client. MATLAB sets up the requested number of workers, each

  6. Parallel MATLAB: Single Program Multiple Data

    E-Print Network [OSTI]

    Crawford, T. Daniel

    Parallel MATLAB: Single Program Multiple Data John Burkardt (FSU) Gene Cliff (AOE/ICAM - ecliff Research Computing ICAM: Interdisciplinary Center for Applied Mathematics 1 / 67 #12;Matlab Parallel ( 'myscript', 'Profile', ... 'ithaca_R2012a', 'matlabpool', 7 ) 5 / 67 #12;SPMD: The SPMD Environment Matlab

  7. Parallel MATLAB: Single Program Multiple Data

    E-Print Network [OSTI]

    Crawford, T. Daniel

    Parallel MATLAB: Single Program Multiple Data John Burkardt (FSU) Gene Cliff (AOE/ICAM - ecliff Research Computing ICAM: Interdisciplinary Center for Applied Mathematics 1 / 66 #12;MATLAB Parallel MATLAB sets up one special worker called the client. MATLAB sets up the requested number of workers, each

  8. Batch Scheduling with Deadlines on Parallel Machines

    E-Print Network [OSTI]

    Magdeburg, Universität

    Batch Scheduling with Deadlines on Parallel Machines Peter Brucker Mikhail Y. Kovalyov, Yakov M of scheduling G groups of jobs on m parallel machines is considered. Each group consists of several identical) and to schedule the batches on the machines. It is possible for different batches of the same group

  9. Abstract AndParallel Machines Nachum Dershowitz

    E-Print Network [OSTI]

    Dershowitz, Nachum

    Abstract And­Parallel Machines Nachum Dershowitz University of Illinois Urbana, IL 61801 U are introduced. The first of them, the And­ Parallel Turing Machine, can be viewed as a generalization of the deterministic Turing machine in which the infinite tape is replaced by an infinite tree­like tape on which

  10. A Framework for Heterogeneous Desktop Parallel Computing

    E-Print Network [OSTI]

    Emmerich, Michael

    that automatically identify independent processes and their data flows inside an application. In this paper, we, painlessly transforms the simple desk- top computer into a computing powerhouse. 1 Introduction Until a few. This is the case of data-parallelism. Data-parallelism is relatively easy with already lots of research dedicated

  11. Parallel Animated Image File Generation Nishad Patel

    E-Print Network [OSTI]

    Kaminsky, Alan

    , frame) · getPixelDataSegmentParameters() · readSegment() #12;Hypotheses · Serial PJM processing times vs. Parallel PJM processing times ­ Parallel PJM should be quicker · Post-processing times vs. In-situ processing times ­ In-situ processing should be quicker · PJM processing times vs. processing times for other

  12. Randomized Parallel Algorithms in Optimization Stephen Wright

    E-Print Network [OSTI]

    Randomized Parallel Algorithms in Optimization Stephen Wright University of Wisconsin-Madison July 2013 Wright (UW-Madison) Random Parallel Optimization July 2013 1 / 52 #12;Collaborators @ UW-Madison Victor Bittorf Ji Liu Ben Recht ( Berkeley) Chris R´e ( Stanford) Krishna Sridhar Wright (UW

  13. X-ray Emission from Massive StarsX-ray Emission from Massive Stars David CohenDavid Cohen

    E-Print Network [OSTI]

    Cohen, David

    X-ray Emission from Massive StarsX-ray Emission from Massive Stars David CohenDavid Cohen/s)Velocity (km/s) #12;absorption emission emission occulted emission emission UV telescope side side front back #12;absorption emission emission occulted emission emission UV telescope side side front back #12;The

  14. Broadcasting a message in a parallel computer

    DOE Patents [OSTI]

    Berg, Jeremy E. (Rochester, MN); Faraj, Ahmad A. (Rochester, MN)

    2011-08-02T23:59:59.000Z

    Methods, systems, and products are disclosed for broadcasting a message in a parallel computer. The parallel computer includes a plurality of compute nodes connected together using a data communications network. The data communications network optimized for point to point data communications and is characterized by at least two dimensions. The compute nodes are organized into at least one operational group of compute nodes for collective parallel operations of the parallel computer. One compute node of the operational group assigned to be a logical root. Broadcasting a message in a parallel computer includes: establishing a Hamiltonian path along all of the compute nodes in at least one plane of the data communications network and in the operational group; and broadcasting, by the logical root to the remaining compute nodes, the logical root's message along the established Hamiltonian path.

  15. Occurrence Frequency of CO Outflows in Massive Protostellar Candidates

    E-Print Network [OSTI]

    Kee-Tae Kim; S. E. Kurtz

    2006-01-24T23:59:59.000Z

    We mapped 12 massive protostellar candidates in the CO J=2-1 line, which in combination with Zhang et al. (2005) completes an unbiased survey of outflows for all 48 sources with l>50^o in a sample of 101 massive protostellar candidates. We detected outflows in 10 sources, implying 88% occurrence frequency of outflows for the 48 sources. This supports the conclusion of previous studies that bipolar outflows are an integral component in the formation process of massive stars. The vast majority of the observed outflows are much more massive (>10~Mo) and energetic (>100~Mo~km/s) than outflows from low-mass protostars. They also have large mass outflow rates (>2x10^{-4}~Mo/yr), suggesting large (~1x10^{-4}~Mo/yr) accretion rates sufficient to overcome radiation pressure of the central massive protostars. We compared the frequency distribution of collimation factors of 40 massive outflows including those of this study with that of 36 low-mass outflows from the literature, and found NO significant difference between the two. All these results are consistent with the suggestion that massive stars form through accretion as do low-mass stars but with much higher accretion rates.

  16. Characterising Vainshtein Solutions in Massive Gravity

    E-Print Network [OSTI]

    Fulvio Sbisa'; Gustavo Niz; Kazuya Koyama; Gianmassimo Tasinato

    2014-06-17T23:59:59.000Z

    We study static, spherically symmetric solutions in a recently proposed ghost-free model of non-linear massive gravity. We focus on a branch of solutions where the helicity-0 mode can be strongly coupled within certain radial regions, giving rise to the Vainshtein effect. We truncate the analysis to scales below the gravitational Compton wavelength, and consider the weak field limit for the gravitational potentials, while keeping all non-linearities of the helicity-0 mode. We determine analytically the number and properties of local solutions which exist asymptotically on large scales, and of local (inner) solutions which exist on small scales. We find two kinds of asymptotic solutions, one of which is asymptotically flat, while the other one is not, and also two types of inner solutions, one of which displays the Vainshtein mechanism, while the other exhibits a self-shielding behaviour of the gravitational field. We analyse in detail in which cases the solutions match in an intermediate region. The asymptotically flat solutions connect only to inner configurations displaying the Vainshtein mechanism, while the non asymptotically flat solutions can connect with both kinds of inner solutions. We show furthermore that there are some regions in the parameter space where global solutions do not exist, and characterise precisely in which regions of the phase space the Vainshtein mechanism takes place.

  17. Radiation Pressure in Massive Star Formation

    E-Print Network [OSTI]

    Mark R. Krumholz; Richard I. Klein; Christopher F. McKee

    2005-10-14T23:59:59.000Z

    Stars with masses of >~ 20 solar masses have short Kelvin times that enable them to reach the main sequence while still accreting from their natal clouds. The resulting nuclear burning produces a huge luminosity and a correspondingly large radiation pressure force on dust grains in the accreting gas. This effect may limit the upper mass of stars that can form by accretion. Indeed, simulations and analytic calculations to date have been unable to resolve the mystery of how stars of 50 solar masses and up form. We present two new ideas to solve the radiation pressure problem. First, we use three-dimensional radiation hydrodynamic adaptive mesh refinement simulations to study the collapse of massive cores. We find that in three dimensions a configuration in which radiation holds up an infalling envelope is Rayleigh-Taylor unstable, leading radiation driven bubbles to collapse and accretion to continue. We also present Monte Carlo radiative transfer calculations showing that the cavities created by protostellar winds provides a valve that allow radiation to escape the accreting envelope, further reducing the ability of radiation pressure to inhibit accretion.

  18. Massive stars in their death-throes

    E-Print Network [OSTI]

    J. J. Eldridge

    2008-09-11T23:59:59.000Z

    The study of the stars that explode as supernovae used to be a forensic study, working backwards from the remnants of the star. This changed in 1987 when the first progenitor star was identified in pre-explosion images. Currently there are 8 detected progenitors with another 21 non-detections, for which only a limit on the pre-explosion luminosity can be placed. This new avenue of supernova research has led to many interesting conclusions, most importantly that the progenitors of the most common supernovae, type IIP, are red supergiants as theory has long predicted. However no progenitors have been detected thus far for the hydrogen-free type Ib/c supernovae which, given the expected progenitors, is an unlikely result. Also observations have begun to show evidence that luminous blue variables, which are among the most massive stars, may directly explode as supernovae. These results contradict current stellar evolution theory. This suggests that we may need to update our understanding.

  19. Superenergy tensors for a massive scalar field

    E-Print Network [OSTI]

    P. Teyssandier

    1999-05-20T23:59:59.000Z

    We define a general class of superenergy tensors of even rank 2(n+1) for a real massive scalar field propagating in Minkowski spacetime. In the case where n=1, we establish that this class is a two-parameter family, which reduces to a unique tensor W(up to a constant factor) when the complete symmetry on the four indices is required. We show that the superenergy density $W^{\\al\\ba\\ga\\da}u_{\\al}u_{\\ba}u_{\\ga}u_{\\da}$ relative to any timelike unit vector $u$ is positive definite and that the supermomentum density $W^{\\al\\ba\\ga\\da}u_{\\ba}u_{\\ga}u_{\\da}$ is a timelike or a null vector ($W^{\\al\\ba\\ga\\da}$ stands for W). Next, we find an infinite set of conserved tensors $U_{(p,q)}$ of rank 2+p+q, that we call weak superenergy tensors of order n when p=q=n. We show that $U_{(1,1)}$ and W yield the same total superenergy and the same total supermomentum. Then, using the canonical quantization scheme, we construct explicitly the superhamiltonian and the supermomentum operators corresponding to W and to each weak superenergy tensor $U_{(n,n)}$. Finally, we exhibit a two-parameter family of superenergy tensors for an electromagnetic field and for a gravitational field.

  20. MASSIVE BLACK HOLES IN CENTRAL CLUSTER GALAXIES

    SciTech Connect (OSTI)

    Volonteri, Marta [Institut d'Astrophysique de Paris, 98bis Bd. Arago, F-75014 Paris (France); Ciotti, Luca [Dipartimento di Fisica e Astronomia, Universita di Bologna, via Ranzani 1, I-40127 Bologna (Italy)

    2013-05-01T23:59:59.000Z

    We explore how the co-evolution of massive black holes (MBHs) and galaxies is affected by environmental effects, addressing in particular MBHs hosted in the central cluster galaxies (we will refer to these galaxies in general as ''CCGs''). Recently, the sample of MBHs in CCGs with dynamically measured masses has increased, and it has been suggested that these MBH masses (M{sub BH}) deviate from the expected correlations with velocity dispersion ({sigma}) and mass of the bulge (M{sub bulge}) of the host galaxy: MBHs in CCGs appear to be ''overmassive''. This discrepancy is more pronounced when considering the M{sub BH}-{sigma} relation than the M{sub BH}-M{sub bulge} one. We show that this behavior stems from a combination of two natural factors: (1) CCGs experience more mergers involving spheroidal galaxies and their MBHs and (2) such mergers are preferentially gas poor. We use a combination of analytical and semi-analytical models to investigate the MBH-galaxy co-evolution in different environments and find that the combination of these two factors is in accordance with the trends observed in current data sets.

  1. 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)

  2. Improved control strategy for parallel logic programming

    SciTech Connect (OSTI)

    Chung, I.J.

    1989-01-01T23:59:59.000Z

    The objective of this dissertation is to formulate an improved control strategy for parallel logic programming and to verify that the complexity of the parallel logic programs with this control strategy would be much less than the complexity of the other logic programs. The proposed control strategy is a combination of committed choice nondeterminism, and the data-flow model. The commit operator would be used for committed choice nondeterminism, and the primitives based on the dataflow model would be used to control AND-parallelism and OR-parallelism. With this proposed control strategy, the maximum useful parallelism can be explained with optimal granularity by controlling useless parallelism and limiting the branching factor. For justification of the proposed control strategy, it is suggested that the complexity of the computations of alternating Turing machines, which include a generalization of nondeterminism, can be used for the abstract cost function of logic programs. As justification of the proposed idea, the author bases a comparison of parallel logic programs on a model utilizing alternating Turing machines. The author shows that a natural reduction of the alternating Turing machine for the proposed control strategy yields a deterministic Turing machine whose complexity is linearly- related to that of the alternating Turing machine. However such a reduction for the conventional committed choice nondeterminism has complexity that is quadratically related to that of the alternating Turing machine.

  3. E-Print Network 3.0 - aicha massive sulphide Sample Search Results

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

    Canada Geological origin Solid specific gravity 3.4 g... Mineralogy (XRD) Conditioning processing Volcanic massive deposit, Portugal Volcanic massive deposit... , Portugal...

  4. Xyce parallel electronic simulator : users' guide.

    SciTech Connect (OSTI)

    Mei, Ting; Rankin, Eric Lamont; Thornquist, Heidi K.; Santarelli, Keith R.; Fixel, Deborah A.; Coffey, Todd Stirling; Russo, Thomas V.; Schiek, Richard Louis; Warrender, Christina E.; Keiter, Eric Richard; Pawlowski, Roger Patrick

    2011-05-01T23:59:59.000Z

    This manual describes the use of the Xyce Parallel Electronic Simulator. Xyce has been designed as a SPICE-compatible, high-performance analog circuit simulator, and has been written to support the simulation needs of the Sandia National Laboratories electrical designers. This development has focused on improving capability over the current state-of-the-art in the following areas: (1) Capability to solve extremely large circuit problems by supporting large-scale parallel computing platforms (up to thousands of processors). Note that this includes support for most popular parallel and serial computers; (2) Improved performance for all numerical kernels (e.g., time integrator, nonlinear and linear solvers) through state-of-the-art algorithms and novel techniques. (3) Device models which are specifically tailored to meet Sandia's needs, including some radiation-aware devices (for Sandia users only); and (4) Object-oriented code design and implementation using modern coding practices that ensure that the Xyce Parallel Electronic Simulator will be maintainable and extensible far into the future. Xyce is a parallel code in the most general sense of the phrase - a message passing parallel implementation - which allows it to run efficiently on the widest possible number of computing platforms. These include serial, shared-memory and distributed-memory parallel as well as heterogeneous platforms. Careful attention has been paid to the specific nature of circuit-simulation problems to ensure that optimal parallel efficiency is achieved as the number of processors grows. The development of Xyce provides a platform for computational research and development aimed specifically at the needs of the Laboratory. With Xyce, Sandia has an 'in-house' capability with which both new electrical (e.g., device model development) and algorithmic (e.g., faster time-integration methods, parallel solver algorithms) research and development can be performed. As a result, Xyce is a unique electrical simulation capability, designed to meet the unique needs of the laboratory.

  5. Characterizing the Separation and Reattachment of Suction Surface Boundary Layer in Low Pressure Turbine Using Massively Parallel Large Eddy Simulations

    E-Print Network [OSTI]

    Jagannathan, Shriram

    2012-02-14T23:59:59.000Z

    cient, p p1 1 2 U21 Cax Axial chord H12 Form factor R11 Correlation coe cient Tu Turbulence intensity Ue Boundary layer edge velocity U1 Freestream velocity 1 Displacement thickness of a boundary layer 2 Momentum thickness of a boundary...

  6. Proc. of IEEE Int. Conf. on Robotics and Automation, San Diego, CA, May 1994. Sensorless Manipulation Using Massively Parallel

    E-Print Network [OSTI]

    Richardson, David

    Proc. of IEEE Int. Conf. on Robotics and Automation, San Diego, CA, May 1994. Sensorless Robert Mihailovich Noel C. MacDonald Robotics & Vision Laboratory \\Lambda School of Electrical in the Robotics and Vi­ sion Laboratory at Cornell University. Support for our robotics research is provided

  7. PUBLISHED ONLINE: 25 APRIL 2010 | DOI: 10.1038/NPHYS1636 Massively parallel computing on an organic

    E-Print Network [OSTI]

    Loss, Daniel

    of the human brain fire at around just 103 times per second, the simultaneous collective action of millions for a new problem or even select a suitable circuit from a few available ones to evolve its hardware1 . However, once the logical path to solve a problem is determined, current is passed through a circuit

  8. HPPC EUROPAR August 31 Naples | Computer Architecture Group, Dept. Computer Science | 1 The Massively Parallel Computing Model GCA

    E-Print Network [OSTI]

    Hoffmann, Rolf

    HPPC ­ EUROPAR August 31 Naples | Computer Architecture Group, Dept. Computer Science | 1 Architecure Group #12;HPPC ­ EUROPAR August 31 Ischia | Computer Architecture Group, Dept. Computer Science Architecture Group, Dept. Computer Science | 3 Outline PART I: Global Cellular Automata (GCA) Cellular

  9. Scalable mpNoC for Massively Parallel Systems Design and Implementation M. Baklouti,a,b

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    , Villeneuve d'ascq, France INRIA Lille Nord Europe, F-59650, Villeneuve d'ascq, France UMR 8022, CNRS, F-59650 Stream Multi- ple Data Stream) architectures. This allows them to speed-up significantly execution times

  10. nature biotechnology volume 31 NumBeR 7 JulY 2013 595 used massively parallel shotgun sequencing

    E-Print Network [OSTI]

    Cai, Long

    and then single-gene disorders, but it's not clear yet which specific technology is going to win this contest pace at which this tech- nology has been integrated into clinical care is unprecedented," says Diana whole fetal cells from the maternal bloodstream. Success for such tests has proved elusive so far

  11. A modular neural interface for massively parallel recording and control : subsystem design considerations for research and clinical applications

    E-Print Network [OSTI]

    Wentz, Christian T

    2010-01-01T23:59:59.000Z

    The closed-loop Brain-Machine Interface (BMI) has long been a dream for clinicians and neuroscience researchers alike - that is, the ability to extract meaningful information from the brain, perform computation on this ...

  12. Massively Parallel Microfluidic Cell-Pairing Platform for the Statistical Study of Immunological Cell-Cell Interactions

    E-Print Network [OSTI]

    Hoehl, Melanie Margarete

    Variability in cell-cell interactions is ubiquitous and particularly relevant for the immune system, where the reliability of cell-cell interactions is critical for the prevention of disease. This variability is poorly ...

  13. Reynolds and Mach Number Scaling in Stationary Compressible Turbulence Using Massively Parallel High Resolution Direct Numerical Simulations

    E-Print Network [OSTI]

    Jagannathan, Shriram

    2014-07-24T23:59:59.000Z

    on the acous- tic time scale leading to a simplified set of equations (Erlebacher et al., 1990; Sarkar et al., 1991). This leads to a flow regime known as low-Mach number quasi-isentropic regime, where the flow evolves only on acoustic time scale... and characterized by small dilatational fluctuations (Sagaut & Cambon, 2008). Under these conditions, Sarkar et al. (1991) observed an equipartition of energy between the compressible kinetic energy and potential energy due to the pressure. The phenomenon...

  14. Distributed parallel messaging for multiprocessor systems

    DOE Patents [OSTI]

    Chen, Dong; Heidelberger, Philip; Salapura, Valentina; Senger, Robert M; Steinmacher-Burrow, Burhard; Sugawara, Yutaka

    2013-06-04T23:59:59.000Z

    A method and apparatus for distributed parallel messaging in a parallel computing system. The apparatus includes, at each node of a multiprocessor network, multiple injection messaging engine units and reception messaging engine units, each implementing a DMA engine and each supporting both multiple packet injection into and multiple reception from a network, in parallel. The reception side of the messaging unit (MU) includes a switch interface enabling writing of data of a packet received from the network to the memory system. The transmission side of the messaging unit, includes switch interface for reading from the memory system when injecting packets into the network.

  15. CS 525: Parallel Computing Spring 2001

    E-Print Network [OSTI]

    Grama, Ananth

    by ping-ponging a message a large number of times and using it to estimate round-trip time and from it through the parallelization strategy carefully before implementing it! Document your results clearly

  16. Parallel VLSI Circuit Analysis and Optimization

    E-Print Network [OSTI]

    Ye, Xiaoji

    2012-02-14T23:59:59.000Z

    CAD application addressed in this dissertation is the Simulation Program with Integrated Circuit Emphasis (SPICE) like circuit simulation. SPICE simulation is often regarded as the bottleneck of the design flow. Recently, parallel circuit simulation...

  17. Provably Efficient Adaptive Scheduling for Parallel Jobs

    E-Print Network [OSTI]

    He, Yuxiong

    Scheduling competing jobs on multiprocessors has always been an important issue for parallel and distributed systems. The challenge is to ensure global, system-wide efficiency while offering a level of fairness to user ...

  18. Parallel Algorithms for Big Data Optimization

    E-Print Network [OSTI]

    2014-02-21T23:59:59.000Z

    Index Terms—Parallel optimization, Distributed methods, Ja- cobi method ... Usually the nonsmooth term is used to ..... dard Armijo-like line-search procedure or a (suitably small) constant ..... enter the identification phase xk i is not zero, the

  19. Parallel magnetic resonance imaging: characterization and comparison

    E-Print Network [OSTI]

    Rane, Swati Dnyandeo

    2005-11-01T23:59:59.000Z

    [Sodickson, 1997], GRAPPA [Griswold, 2002] and SPACE RIP [Kyriakos, 2000]; developed in the past decade have been studied, simulated and compared in this research. Because of the dependence of the parallel imaging methods on numerous factors such as receiver...

  20. Parallel programming with PCN. Revision 1

    SciTech Connect (OSTI)

    Foster, I.; Tuecke, S.

    1991-12-01T23:59:59.000Z

    PCN is a system for developing and executing parallel programs. It comprises a high-level programming language, tools for developing and debugging programs in this language, and interfaces to Fortran and C that allow the reuse of existing code in multilingual parallel programs. Programs developed using PCN are portable across many different workstations, networks, and parallel computers. This document provides all the information required to develop parallel programs with the PCN programming system. In includes both tutorial and reference material. It also presents the basic concepts that underly PCN, particularly where these are likely to be unfamiliar to the reader, and provides pointers to other documentation on the PCN language, programming techniques, and tools. PCN is in the public domain. The latest version of both the software and this manual can be obtained by anonymous FTP from Argonne National Laboratory in the directory pub/pcn at info.mcs.anl.gov (c.f. Appendix A).

  1. Constraint Satisfaction Via Partially Parallel Propagation Steps

    E-Print Network [OSTI]

    Walter Hower Institut; Walter Hower

    1992-01-01T23:59:59.000Z

    to variables according to existing constraints. Given n variables with n-tuples which represents the globally consistent solution. This article presents a parallel approach to global constraint satisfaction. 0

  2. Phenomenon of electrization caused by gravitation of massive body

    E-Print Network [OSTI]

    D. A. Kirzhnits; A. A. Shatskiy

    2000-10-25T23:59:59.000Z

    The value of excess charge in the kernel of massive body (and the opposite in sign excess charge at the surface) caused by the influence of gravitational forces is determined.

  3. Power-Demand Routing in massive geo-distributed systems

    E-Print Network [OSTI]

    Qureshi, Asfandyar

    2010-01-01T23:59:59.000Z

    There is an increasing trend toward massive, geographically distributed systems. The largest Internet companies operate hundreds of thousands of servers in multiple geographic locations, and are growing at a fast clip. A ...

  4. An alternative derivation of the Minimal massive 3D gravity

    E-Print Network [OSTI]

    Ahmet Baykal

    2014-08-22T23:59:59.000Z

    By using the algebra of exterior forms and the first order formalism with constraints, an alternative derivation of the field equations for the Minimal massive 3D gravity model is presented.

  5. Topologically Massive Gravity and Ricci-Cotton Flow

    E-Print Network [OSTI]

    Nima Lashkari; Alexander Maloney

    2010-09-14T23:59:59.000Z

    We consider Topologically Massive Gravity (TMG), which is three dimensional general relativity with a cosmological constant and a gravitational Chern-Simons term. When the cosmological constant is negative the theory has two potential vacuum solutions: Anti-de Sitter space and Warped Anti-de Sitter space. The theory also contains a massive graviton state which renders these solutions unstable for certain values of the parameters and boundary conditions. We study the decay of these solutions due to the condensation of the massive graviton mode using Ricci-Cotton flow, which is the appropriate generalization of Ricci flow to TMG. When the Chern-Simons coupling is small the AdS solution flows to warped AdS by the condensation of the massive graviton mode. When the coupling is large the situation is reversed, and warped AdS flows to AdS. Minisuperspace models are constructed where these flows are studied explicitly.

  6. Topologically Massive Gravity and Ricci-Cotton Flow

    E-Print Network [OSTI]

    Lashkari, Nima

    2010-01-01T23:59:59.000Z

    We consider Topologically Massive Gravity (TMG), which is three dimensional general relativity with a cosmological constant and a gravitational Chern-Simons term. When the cosmological constant is negative the theory has two potential vacuum solutions: Anti-de Sitter space and Warped Anti-de Sitter space. The theory also contains a massive graviton state which renders these solutions unstable for certain values of the parameters and boundary conditions. We study the decay of these solutions due to the condensation of the massive graviton mode using Ricci-Cotton flow, which is the appropriate generalization of Ricci flow to TMG. When the Chern-Simons coupling is small the AdS solution flows to warped AdS by the condensation of the massive graviton mode. When the coupling is large the situation is reversed, and warped AdS flows to AdS. Minisuperspace models are constructed where these flows are studied explicitly.

  7. Performance evaluation of scalable parallel computing networks

    E-Print Network [OSTI]

    Wilkinson, Robert Todd

    1996-01-01T23:59:59.000Z

    PERFORMANCE EVALUATION OF SCALABLE PARALLEL COMPUTING NETWORKS A Thesis by ROBERT TODD WILKINSON Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE May 1996 Major Subject: Computer Science PERFORMANCE EVALUATION OF SCALABLE PARALLEL COiVIPUTING NETWORKS A Thesis by ROBERT TODD WILKINSON Submitted to Texas ARM University in partial fulfillment of the requirements for the degree...

  8. LDV Measurement of Confined Parallel Jet Mixing

    SciTech Connect (OSTI)

    R.F. Kunz; S.W. D'Amico; P.F. Vassallo; M.A. Zaccaria

    2001-01-31T23:59:59.000Z

    Laser Doppler Velocimetry (LDV) measurements were taken in a confinement, bounded by two parallel walls, into which issues a row of parallel jets. Two-component measurements were taken of two mean velocity components and three Reynolds stress components. As observed in isolated three dimensional wall bounded jets, the transverse diffusion of the jets is quite large. The data indicate that this rapid mixing process is due to strong secondary flows, transport of large inlet intensities and Reynolds stress anisotropy effects.

  9. Parallel Implementation of Gamma-Point Pseudopotential Plane...

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

    Parallel Implementation of Gamma-Point Pseudopotential Plane-Wave DFT with Exact Exchange. Parallel Implementation of Gamma-Point Pseudopotential Plane-Wave DFT with Exact...

  10. Chassis Dynamometer Testing of Parallel and Series Diesel Hybrid...

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

    Chassis Dynamometer Testing of Parallel and Series Diesel Hybrid Buses Chassis Dynamometer Testing of Parallel and Series Diesel Hybrid Buses Emissions and fuel economy data were...

  11. Massive Gravity from Higher Derivative Gravity with Boundary Conditions

    E-Print Network [OSTI]

    Minjoon Park; Lorenzo Sorbo

    2012-10-29T23:59:59.000Z

    With an appropriate choice of parameters, a higher derivative theory of gravity can describe a normal massive sector and a ghost massless sector. We show that, when defined on an asymptotically de Sitter spacetime with Dirichlet boundary conditions, such a higher derivative gravity can provide a framework for a unitary theory of massive gravity in four spacetime dimensions. The resulting theory is free not only of higher derivative ghosts but also of the Boulware-Deser mode.

  12. The Early Evolution of Massive Stars: Radio Recombination Line Spectra

    E-Print Network [OSTI]

    Eric Keto; Qizhou Zhang; Stanley Kurtz

    2007-11-15T23:59:59.000Z

    Velocity shifts and differential broadening of radio recombination lines are used to estimate the densities and velocities of the ionized gas in several hypercompact and ultracompact HII regions. These small HII regions are thought to be at their earliest evolutionary phase and associated with the youngest massive stars. The observations suggest that these HII regions are characterized by high densities, supersonic flows and steep density gradients, consistent with accretion and outflows that would be associated with the formation of massive stars.

  13. Capture Formed Binaries via Encounters with Massive Protostars

    E-Print Network [OSTI]

    Nickolas Moeckel; John Bally

    2006-10-20T23:59:59.000Z

    Most massive stars are found in the center of dense clusters, and have a companion fraction much higher than their lower mass siblings; the massive stars of the Trapezium core in Orion have ~ 1.5 companions each. This high multiplicity could be a consequence of formation via a capture scenario, or it could be due to fragmentation of the cores that form the massive stars. During stellar formation circumstellar disks appear to be nearly ubiquitous. Their large radii compared to stellar sizes increase the interaction radius significantly, suggesting that disk interactions with neighboring stars could assist in capturing binary companions. This mechanism has been studied for stars of approximately solar mass and found to be inefficient. In this paper we present simulations of interactions between a 22 Msun star-disk system and less massive impactors, to study the disk-assisted capture formation of binaries in a regime suited to massive stars. The formation of binaries by capture is found to be much more efficient for massive capturers. We discuss the effects of a mass dependent velocity dispersion and mass segregation on the capture rates, and consider the long term survival of the resultant binaries in a dense cluster.

  14. A methodology for deriving parallel programs with a family of Abstract Parallel Machines

    E-Print Network [OSTI]

    O'Donnell, J.T.

    O'Donnell,J.T. Runger,G. Lecture Notes in Computer Science. Volume 1300. Euro-Par'97: Parallel Processing (Passau, Germany) pp 662-669 Springer

  15. SCORPIO: A Scalable Two-Phase Parallel I/O Library With Application To A Large Scale Subsurface Simulator

    SciTech Connect (OSTI)

    Sreepathi, Sarat [ORNL] [ORNL; Sripathi, Vamsi [Intel Corporation] [Intel Corporation; Mills, Richard T [ORNL] [ORNL; Hammond, Glenn [Pacific Northwest National Laboratory (PNNL)] [Pacific Northwest National Laboratory (PNNL); Mahinthakumar, Kumar [North Carolina State University] [North Carolina State University

    2013-01-01T23:59:59.000Z

    Inefficient parallel I/O is known to be a major bottleneck among scientific applications employed on supercomputers as the number of processor cores grows into the thousands. Our prior experience indicated that parallel I/O libraries such as HDF5 that rely on MPI-IO do not scale well beyond 10K processor cores, especially on parallel file systems (like Lustre) with single point of resource contention. Our previous optimization efforts for a massively parallel multi-phase and multi-component subsurface simulator (PFLOTRAN) led to a two-phase I/O approach at the application level where a set of designated processes participate in the I/O process by splitting the I/O operation into a communication phase and a disk I/O phase. The designated I/O processes are created by splitting the MPI global communicator into multiple sub-communicators. The root process in each sub-communicator is responsible for performing the I/O operations for the entire group and then distributing the data to rest of the group. This approach resulted in over 25X speedup in HDF I/O read performance and 3X speedup in write performance for PFLOTRAN at over 100K processor cores on the ORNL Jaguar supercomputer. This research describes the design and development of a general purpose parallel I/O library, SCORPIO (SCalable block-ORiented Parallel I/O) that incorporates our optimized two-phase I/O approach. The library provides a simplified higher level abstraction to the user, sitting atop existing parallel I/O libraries (such as HDF5) and implements optimized I/O access patterns that can scale on larger number of processors. Performance results with standard benchmark problems and PFLOTRAN indicate that our library is able to maintain the same speedups as before with the added flexibility of being applicable to a wider range of I/O intensive applications.

  16. Trinomialtree based parallel option price Alexandros V. Gerbessiotis

    E-Print Network [OSTI]

    Gerbessiotis, Alexandros V.

    can be performed in parallel. We introduce a method in performing these valuations in parallelTrinomial­tree based parallel option price valuations Alexandros V. Gerbessiotis Department; Trinomial­tree based parallel option price valuations Alexandros V. Gerbessiotis CS Department New Jersey

  17. Salvador de Bahia, 2008 1 Parallel Computing: General

    E-Print Network [OSTI]

    Giménez, Domingo

    Salvador de Bahia, 2008 1 Parallel Computing: General Perspective and Applications Domingo Giménez://dis.um.es/~domingo #12;Salvador de Bahia, 2008 2 Content General aspects of parallel computing Necessity of parallel Case study II: Meteorology #12;Salvador de Bahia, 2008 3 Parallel Computing Several processors working

  18. Lazy Parallelization: A Finite State Machine Based Optimization Approach for Data Parallel Image Processing Applications

    E-Print Network [OSTI]

    Seinstra, Frank J.

    performance image processing applications is often sub-optimal. This is be- cause inter-operation optimization performance optimization to each library operation in isolation, and ignore global opti- mization for fullLazy Parallelization: A Finite State Machine Based Optimization Approach for Data Parallel Image

  19. 1996 InternationalConference on Parallel Processing PARALLEL IMPLEMENTATION OF CONE BEAM TOMOGRAPHY

    E-Print Network [OSTI]

    Chaudhary, Vipin

    projections us- ing computed tomography (CT) is the noninvasive measure of structure from external as follows: A. Weight projection data B. Convolve weighted projection data Pe*(u,v) = P&L, U) * h(u) C1996 InternationalConference on Parallel Processing PARALLEL IMPLEMENTATION OF CONE BEAM TOMOGRAPHY

  20. Data communications in a parallel active messaging interface of a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J; Blocksome, Michael A; Ratterman, Joseph D; Smith, Brian E

    2013-11-12T23:59:59.000Z

    Data communications in a parallel active messaging interface (`PAMI`) of a parallel computer composed of compute nodes that execute a parallel application, each compute node including application processors that execute the parallel application and at least one management processor dedicated to gathering information regarding data communications. The PAMI is composed of data communications endpoints, each endpoint composed of a specification of data communications parameters for a thread of execution on a compute node, including specifications of a client, a context, and a task, the compute nodes and the endpoints coupled for data communications through the PAMI and through data communications resources. Embodiments function by gathering call site statistics describing data communications resulting from execution of data communications instructions and identifying in dependence upon the call cite statistics a data communications algorithm for use in executing a data communications instruction at a call site in the parallel application.

  1. The Assembly History of Massive Galaxies: What Do We Know?

    E-Print Network [OSTI]

    Christopher J. Conselice

    2007-06-23T23:59:59.000Z

    Understanding the formation history of massive galaxies is one of most popular and longstanding problems in astronomy, with observations and theory addressing how and when these systems assembled. Since the most massive galaxies in today's universe, with M_*> 10^11 M_0, are nearly all elliptical with uniform old stellar populations, we must probe higher redshifts to discover their full origins. A recent consensus has developed that nearly all M_* > 10^11 M_0 galaxies we see today were established by z~1, with at most a factor of two growth in stellar mass and number densities at lower redshifts. We review the evidence for this, and discuss how recent observations of star formation rates, colors, and morphologies of massive galaxies at z 10^11 M_0 show that these systems are still experiencing some evolution. Massive galaxies undergo on average a single major merger at z 10^11.5 M_0, appear in similar abundance at z 1.5 demonstrate that major galaxy mergers are the primary method for assembling these massive galaxies, with nearly all of this merging occurring at z > 2, with on average 4 to 5 major mergers taking place at z = 1.5 - 3.

  2. Java Parallel Secure Stream for Grid Computing

    SciTech Connect (OSTI)

    Chen, Jie; Akers, Walter; Chen, Ying; Watson, William

    2001-09-01T23:59:59.000Z

    The emergence of high speed wide area networks makes grid computing a reality. However grid applications that need reliable data transfer still have difficulties to achieve optimal TCP performance due to network tuning of TCP window size to improve the bandwidth and to reduce latency on a high speed wide area network. This paper presents a pure Java package called JPARSS (Java Par-allel Secure Stream) that divides data into partitions that are sent over several parallel Java streams simultaneously and allows Java or Web applications to achieve optimal TCP performance in a gird environment without the necessity of tuning the TCP window size. Several experimental results are provided to show that using parallel stream is more effective than tuning TCP window size. In addi-tion X.509 certificate based single sign-on mechanism and SSL based connection establishment are integrated into this package. Finally a few applications using this package will be discussed.

  3. Xyce parallel electronic simulator release notes.

    SciTech Connect (OSTI)

    Keiter, Eric Richard; Hoekstra, Robert John; Mei, Ting; Russo, Thomas V.; Schiek, Richard Louis; Thornquist, Heidi K.; Rankin, Eric Lamont; Coffey, Todd Stirling; Pawlowski, Roger Patrick; Santarelli, Keith R.

    2010-05-01T23:59:59.000Z

    The Xyce Parallel Electronic Simulator has been written to support, in a rigorous manner, the simulation needs of the Sandia National Laboratories electrical designers. Specific requirements include, among others, the ability to solve extremely large circuit problems by supporting large-scale parallel computing platforms, improved numerical performance and object-oriented code design and implementation. The Xyce release notes describe: Hardware and software requirements New features and enhancements Any defects fixed since the last release Current known defects and defect workarounds For up-to-date information not available at the time these notes were produced, please visit the Xyce web page at http://www.cs.sandia.gov/xyce.

  4. 18.337J / 6.338J Applied Parallel Computing (SMA 5505), Spring 2005

    E-Print Network [OSTI]

    Edelman, Alan

    Applied Parallel Computing is an advanced interdisciplinary introduction to applied parallel computing on modern supercomputers.

  5. A Pervasive Parallel Processing Framework For Data Visualization And Analysis At Extreme Scale Final Scientific and Technical Report

    SciTech Connect (OSTI)

    Geveci, Berk

    2014-10-31T23:59:59.000Z

    The evolution of the computing world from teraflop to petaflop has been relatively effortless,with several of the existing programming models scaling effectively to the petascale. The migration to exascale, however, poses considerable challenges. All industry trends infer that the exascale machine will be built using processors containing hundreds to thousands of cores per chip. It can be inferred that efficient concurrency on exascale machines requires a massive amount of concurrent threads, each performing many operations on a localized piece of data. Currently, visualization libraries and applications are based off what is known as the visualization pipeline. In the pipeline model, algorithms are encapsulated as filters with inputs and outputs. These filters are connected by setting the output of one component to the input of another. Parallelism in the visualization pipeline is achieved by replicating the pipeline for each processing thread. This works well for today’s distributed memory parallel computers but cannot be sustained when operating on processors with thousands of cores. Our project investigates a new visualization framework designed to exhibit the pervasive parallelism necessary for extreme scale machines. Our framework achieves this by defining algorithms in terms of worklets, which are localized stateless operations. Worklets are atomic operations that execute when invoked unlike filters, which execute when a pipeline request occurs. The worklet design allows execution on a massive amount of lightweight threads with minimal overhead. Only with such fine-grained parallelism can we hope to fill the billions of threads we expect will be necessary for efficient computation on an exascale machine.

  6. Star Formation and Merging in Massive Galaxies at z < 2

    E-Print Network [OSTI]

    Christopher J. Conselice

    2008-06-14T23:59:59.000Z

    Observing massive galaxies at various redshifts is one of the most straightforward and direct approaches towards understanding galaxy formation. There is now largely a consensus that the massive galaxy (M_* > 10^11 M_0) population is fully formed by z~1, based on mass and luminosity functions. However, we argue that the latest data can only rule out number and mass density evolution of a factor of > 2-3 at z 10^11 M_0 galaxies reveals that 40+/-5% of galaxies with M_* > 10^11 M_0 at z~1 are undergoing star formation that effectively doubles their stellar mass between z = 0.4 - 1.4. These massive galaxies also undergo 0.9^+0.7_-0.5 major mergers during this same time period.

  7. Massive Stars in Colliding Wind Systems: the GLAST Perspective

    SciTech Connect (OSTI)

    Reimer, Anita; Reimer, Olaf; /Stanford U., HEPL /KIPAC, Menlo Park

    2011-11-29T23:59:59.000Z

    Colliding winds of massive stars in binary systems are considered as candidate sites of high-energy non-thermal photon emission. They are already among the suggested counterparts for a few individual unidentified EGRET sources, but may constitute a detectable source population for the GLAST observatory. The present work investigates such population study of massive colliding wind systems at high-energy gamma-rays. Based on the recent detailed model (Reimer et al. 2006) for non-thermal photon production in prime candidate systems, we unveil the expected characteristics of this source class in the observables accessible at LAT energies. Combining the broadband emission model with the presently cataloged distribution of such systems and their individual parameters allows us to conclude on the expected maximum number of LAT-detections among massive stars in colliding wind binary systems.

  8. Massive Black Hole Science with eLISA

    E-Print Network [OSTI]

    Enrico Barausse; Jillian Bellovary; Emanuele Berti; Kelly Holley-Bockelmann; Brian Farris; Bangalore Sathyaprakash; Alberto Sesana

    2015-01-09T23:59:59.000Z

    The evolving Laser Interferometer Space Antenna (eLISA) will revolutionize our understanding of the formation and evolution of massive black holes along cosmic history by probing massive black hole binaries in the $10^3-10^7$ solar mass range out to redshift $z\\gtrsim 10$. High signal-to-noise ratio detections of $\\sim 10-100$ binary coalescences per year will allow accurate measurements of the parameters of individual binaries (such as their masses, spins and luminosity distance), and a deep understanding of the underlying cosmic massive black hole parent population. This wealth of unprecedented information can lead to breakthroughs in many areas of physics, including astrophysics, cosmology and fundamental physics. We review the current status of the field, recent progress and future challenges.

  9. THE PAIR FRACTION OF MASSIVE GALAXIES AT 0 {<=} z {<=} 3

    SciTech Connect (OSTI)

    Man, Allison W. S.; Toft, Sune; Zirm, Andrew W. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen (Denmark); Wuyts, Stijn [Max-Planck-Institut fuer Extraterrestrische Physik, Garching bei Muenchen (Germany); Van der Wel, Arjen, E-mail: allison@dark-cosmology.dk, E-mail: sune@dark-cosmology.dk, E-mail: azirm@dark-cosmology.dk, E-mail: swuyts@mpe.mpg.de, E-mail: vdwel@mpia.de [Max-Planck-Institut fuer Astronomie, Heidelberg (Germany)

    2012-01-10T23:59:59.000Z

    Using a mass-selected (M{sub *} {>=} 10{sup 11} M{sub Sun }) sample of 198 galaxies at 0 {<=} z {<=} 3.0 with Hubble Space Telescope/NICMOS H{sub 160}-band images from the COSMOS survey, we find evidence for the evolution of the pair fraction above z {approx} 2, an epoch in which massive galaxies are believed to undergo significant structural and mass evolution. We observe that the pair fraction of massive galaxies is 0.15 {+-} 0.08 at 1.7 {<=}z {<=} 3.0, where galaxy pairs are defined as massive galaxies having a companion of flux ratio from 1:1 to 1:4 within a projected separation of 30 kpc. This is slightly lower but still consistent with the pair fraction measured previously in other studies, and the merger fraction predicted in halo-occupation modeling. The redshift evolution of the pair fraction is described by a power law F(z) = (0.07 {+-} 0.04) Multiplication-Sign (1 + z){sup 0.6{+-}0.5}. The merger rate is consistent with no redshift evolution; however it is difficult to constrain due to the limited sample size and the high uncertainties in the merging timescale. Based on the merger rate calculation, we estimate that a massive galaxy undergoes on average 1.1 {+-} 0.5 major mergers from z = 3 to 0. The observed merger fraction is sufficient to explain the number density evolution of massive galaxies, but insufficient to explain the size evolution. This is a hint that mechanism(s) other than major merging may be required to increase the sizes of the massive, compact quiescent galaxies from z {approx} 2 to 0.

  10. The winds of the hot massive first stars

    E-Print Network [OSTI]

    J. Krticka; J. Kubat

    2005-09-07T23:59:59.000Z

    We study dynamical aspects of circumstellar environment around massive zero-metallicity first stars. For this purpose we apply our NLTE wind models. We show that the hydrogen-helium stellar wind from stationary massive first generation (Population III) stars (driven either by the line (bound-bound) or continuum (bound-free and free-free) transitions) is unlikely. The possibility of expulsion of chemically homogeneous wind and the role of minor isotopes are also discussed. Finally, we estimate the importance of hydrogen and helium lines for shutting off the initial accretion onto first stars and its influence on initial mass function of first stars.

  11. Energy momentum flows for the massive vector field

    E-Print Network [OSTI]

    George Horton; Chris Dewdney

    2006-09-26T23:59:59.000Z

    We present a causal trajectory interpretation for the massive vector field, based on the flows of rest energy and a conserved density defined using the time-like eigenvectors and eigenvalues of the stress-energy-momentum tensor. This work extends our previous work which used a similar procedure for the scalar field. The massive, spin-one, complex vector field is discussed in detail and solutions are classified using the Pauli-Lubanski spin vector. The flows of energy-momentum are illustrated in a simple example of standing waves in a plane.

  12. On Solutions of Minimal Massive 3D Gravity

    E-Print Network [OSTI]

    Arvanitakis, Alex S

    2015-01-01T23:59:59.000Z

    We look at solutions of Minimal Massive Gravity (MMG), a generalisation of Topologically Massive Gravity (TMG) that improves upon its holographic properties. It is shown that generically (in MMG parameter space) all conformally flat solutions of vacuum MMG are locally isometric to one of the two (A)dS vacua of the theory. We then couple a scalar field, and find that domain wall solutions can only interpolate between these two vacua precisely when the bulk graviton is tachyonic. Finally, we find a non-BTZ AdS black hole solution satisfying Brown-Henneaux boundary conditions, which lies within the "bulk/ boundary unitarity region".

  13. Particle-Antiparticle Metamorphosis of Massive Majorana Neutrinos and Gauginos

    E-Print Network [OSTI]

    D. V. Ahluwalia-Khalilova

    2003-06-13T23:59:59.000Z

    Recent results on neutrinoless double beta decay, as reported by Klapdor-Kleingrothaus et al., take us for the first time into the realm of Majorana spacetime structure. However, this structure has either been treated as an afterthought to the Dirac construct; or, when it has been attended to in its own right, its physical and mathematical content was never fully unearthed. In this Letter,we undertake to remedy the existing situation. We present a detailed formalism required for the description of the non-trivial spacetime structure underlying the "nu-nubar" metamorphosis - where "nu" generically represents a massive Majorana neutrino, or a massive gaugino.

  14. One-loop divergences in massive gravity theory

    E-Print Network [OSTI]

    Ioseph L. Buchbinder; Dante D. Pereira; Ilya L. Shapiro

    2012-01-16T23:59:59.000Z

    The one-loop divergences are calculated for the recently proposed ghost-free version of massive gravity, where the action depends on both metric and external tensor field f. The non-polynomial structure of the massive term is reduced to a more standard form by means of auxiliary tensor field, which is settled on-shell after quantum calculations are performed. As one should expect, the counterterms do not reproduce the form of the classical action. Moreover, the result has the form of the power series in f.

  15. Parallel FE Electron-Photon Transport Analysis on 2-D Unstructured Mesh

    SciTech Connect (OSTI)

    Drumm, C.R.; Lorenz, J.

    1999-03-02T23:59:59.000Z

    A novel solution method has been developed to solve the coupled electron-photon transport problem on an unstructured triangular mesh. Instead of tackling the first-order form of the linear Boltzmann equation, this approach is based on the second-order form in conjunction with the conventional multi-group discrete-ordinates approximation. The highly forward-peaked electron scattering is modeled with a multigroup Legendre expansion derived from the Goudsmit-Saunderson theory. The finite element method is used to treat the spatial dependence. The solution method is unique in that the space-direction dependence is solved simultaneously, eliminating the need for the conventional inner iterations, a method that is well suited for massively parallel computers.

  16. A parallel scaled conjugate-gradient

    E-Print Network [OSTI]

    Aykanat, Cevdet

    . The scaled conjugate- gradient method is a powerful technique for solving large sparse linear systems for form-factor computation. Key words: Gathering radiosity -- Scaled conjugate-gradient method -- Parallel, the Gauss--Jacobi (GJ) method is used in the solution phase. The scaled conjugate-gradient (SCG) method

  17. Parallel MATLAB: Single Program Multiple Data

    E-Print Network [OSTI]

    Crawford, T. Daniel

    Parallel MATLAB: Single Program Multiple Data John Burkardt (FSU) Gene Cliff (AOE/ICAM - ecliff: Advanced Research Computing ICAM: Interdisciplinary Center for Applied Mathematics 1 / 69 #12;Matlab ( 'myscript', 'Profile', ... 'ithaca_R2012a', 'matlabpool', 7 ) 5 / 69 #12;SPMD: The SPMD Environment Matlab

  18. Performance studies of the parallel VIM code

    SciTech Connect (OSTI)

    Shi, B.; Blomquist, R.N. [Argonne National Laboratory, IL (United States)

    1996-12-31T23:59:59.000Z

    In this paper, we evaluate the performance of the parallel version of the VIM Monte Carlo code on the IBM SPx at the High Performance Computing Research Facility at Argonne National Laboratory. Three test problems with contrasting computational characteristics were used to assess effects in performance. A statistical method for estimating the inefficiencies due to load imbalance and communication is also introduced.

  19. Performance studies of the parallel VIM code

    SciTech Connect (OSTI)

    Shi, B.; Blomquist, R.N. [Argonne National Lab., IL (United States). Reactor Analysis Div.

    1996-05-01T23:59:59.000Z

    In this paper, the authors evaluate the performance of the parallel version of the VIM Monte Carlo code on the IBM SPx at the High Performance Computing Research Facility at ANL. Three test problems with contrasting computational characteristics were used to assess effects in performance. A statistical method for estimating the inefficiencies due to load imbalance and communication is also introduced. VIM is a large scale continuous energy Monte Carlo radiation transport program and was parallelized using history partitioning, the master/worker approach, and p4 message passing library. Dynamic load balancing is accomplished when the master processor assigns chunks of histories to workers that have completed a previously assigned task, accommodating variations in the lengths of histories, processor speeds, and worker loads. At the end of each batch (generation), the fission sites and tallies are sent from each worker to the master process, contributing to the parallel inefficiency. All communications are between master and workers, and are serial. The SPx is a scalable 128-node parallel supercomputer with high-performance Omega switches of 63 {micro}sec latency and 35 MBytes/sec bandwidth. For uniform and reproducible performance, they used only the 120 identical regular processors (IBM RS/6000) and excluded the remaining eight planet nodes, which may be loaded by other`s jobs.

  20. (Parallel Linear Algebra Package) Jess Cmara Moreno

    E-Print Network [OSTI]

    Giménez, Domingo

    álgebra lineal (Linear Algebra Objects). También permite la utilización de vistas (objetos referenciadosPLAPACK (Parallel Linear Algebra Package) Jesús Cámara Moreno Programación Paralela y Computación Reducción de Vectores Inicialización de PLAPACK. Funciones. Templates. Funciones. Linear Algebra Objects

  1. Message passing with parallel queue traversal

    DOE Patents [OSTI]

    Underwood, Keith D. (Albuquerque, NM); Brightwell, Ronald B. (Albuquerque, NM); Hemmert, K. Scott (Albuquerque, NM)

    2012-05-01T23:59:59.000Z

    In message passing implementations, associative matching structures are used to permit list entries to be searched in parallel fashion, thereby avoiding the delay of linear list traversal. List management capabilities are provided to support list entry turnover semantics and priority ordering semantics.

  2. Parallelized Interpolation: A Quantitative Assessment Scott Blaha

    E-Print Network [OSTI]

    Danner, Andrew

    Parallelized Interpolation: A Quantitative Assessment Scott Blaha Swarthmore College Mustafa Paksoy- cent I/O-efficient point cloud to DEM algorithm (0), from 52% to 86% of running time was spent inter-off in interpolation is quality (e.g. representativeness) of the resulting DEM ver- sus the computational complexity

  3. Parallel programming with PCN. Revision 2

    SciTech Connect (OSTI)

    Foster, I.; Tuecke, S.

    1993-01-01T23:59:59.000Z

    PCN is a system for developing and executing parallel programs. It comprises a high-level programming language, tools for developing and debugging programs in this language, and interfaces to Fortran and Cthat allow the reuse of existing code in multilingual parallel programs. Programs developed using PCN are portable across many different workstations, networks, and parallel computers. This document provides all the information required to develop parallel programs with the PCN programming system. It includes both tutorial and reference material. It also presents the basic concepts that underlie PCN, particularly where these are likely to be unfamiliar to the reader, and provides pointers to other documentation on the PCN language, programming techniques, and tools. PCN is in the public domain. The latest version of both the software and this manual can be obtained by anonymous ftp from Argonne National Laboratory in the directory pub/pcn at info.mcs. ani.gov (cf. Appendix A). This version of this document describes PCN version 2.0, a major revision of the PCN programming system. It supersedes earlier versions of this report.

  4. Instrumentation for parallel magnetic resonance imaging

    E-Print Network [OSTI]

    Brown, David Gerald

    2007-04-25T23:59:59.000Z

    of the art of parallel MR imaging. First, a low-cost desktop MR scanner was developed (2.54 cm fields-of view) at low magnetic field strengths (25 T). The performance of the prototype was verified through bench...

  5. Decomposing Linear Programs for Parallel Solution?

    E-Print Network [OSTI]

    �atalyürek, �mit V.

    Decomposing Linear Programs for Parallel Solution? Ali P nar, Umit V. Catalyurek, Cevdet Aykanat in the solution of Linear Programming (LP) problems with block angular constraint matrices has been exploited industrial applications and the advent of powerful computers have in- creased the users' ability to formulate

  6. Decomposing Linear Programs for Parallel Solution ?

    E-Print Network [OSTI]

    �atalyürek, �mit V.

    Decomposing Linear Programs for Parallel Solution ? Ali Pinar, ¨ Umit V. C¸ ataly¨urek, Cevdet in the solution of Linear Programming (LP) problems with block angular constraint matrices has been exploited with successful industrial applications and the advent of powerful computers have in­ creased the users' ability

  7. Original article Parallel selection of ethanol

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Original article Parallel selection of ethanol and acetic-acid tolerance in Drosophila melanogaster significantly with latitude (0.036 ! 0.004 for 1° latitude; genetic divergence FST = 0.25). Patterns of ethanol of latitudinal ethanol tolerance (10 to 15%) and acetic-acid tolerance (3.7 to 13.2%) were observed in adult

  8. Data communications in a parallel active messaging interface of a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J; Blocksome, Michael A; Ratterman, Joseph D; Smith, Brian E

    2014-02-11T23:59:59.000Z

    Data communications in a parallel active messaging interface ('PAMI') or a parallel computer, the parallel computer including a plurality of compute nodes that execute a parallel application, the PAMI composed of data communications endpoints, each endpoint including a specification of data communications parameters for a thread of execution of a compute node, including specification of a client, a context, and a task, the compute nodes and the endpoints coupled for data communications instruction, the instruction characterized by instruction type, the instruction specifying a transmission of transfer data from the origin endpoint to a target endpoint and transmitting, in accordance witht the instruction type, the transfer data from the origin endpoin to the target endpoint.

  9. Data communications in a parallel active messaging interface of a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J; Blocksome, Michael A; Ratterman, Joseph D; Smith, Brian E

    2013-10-29T23:59:59.000Z

    Data communications in a parallel active messaging interface (`PAMI`) of a parallel computer, the parallel computer including a plurality of compute nodes that execute a parallel application, the PAMI composed of data communications endpoints, each endpoint including a specification of data communications parameters for a thread of execution on a compute node, including specifications of a client, a context, and a task, the compute nodes and the endpoints coupled for data communications through the PAMI and through data communications resources, including receiving in an origin endpoint of the PAMI a data communications instruction, the instruction characterized by an instruction type, the instruction specifying a transmission of transfer data from the origin endpoint to a target endpoint and transmitting, in accordance with the instruction type, the transfer data from the origin endpoint to the target endpoint.

  10. Delusional Boot: Securing Cloud Hypervisors without Massive Re-engineering

    E-Print Network [OSTI]

    Hunt, Galen

    Delusional Boot: Securing Cloud Hypervisors without Massive Re-engineering Anh Nguyen , Himanshu an obstacle: the boot process of many commodity OSes depends on legacy virtual devices absent from our hypervisor. Min-V introduces delusional boot, a mechanism that allows guest VMs run- ning commodity OSes

  11. INTRODUCTION The massive sulfide deposits of southern Spain

    E-Print Network [OSTI]

    van Geen, Alexander

    INTRODUCTION The massive sulfide deposits of southern Spain and Portugal were formed about 300 Ma). Spain became a Roman province, and mining of the rich deposits of the Iberian pyrite belt for copper, California 94025 A. Palanques Instituto de Ciencias del Mar, 08039 Barcelona, Spain ABSTRACT A metal

  12. Effective Matter Cosmologies of Massive Gravity: Physical Fluids

    E-Print Network [OSTI]

    Nejat Tevfik Yilmaz

    2014-12-16T23:59:59.000Z

    We derive new cosmological solutions of the ghost-free massive gravity with a general background metric in which the contribution of the mass sector to the metric one is modeled by an effective cosmological constant and an ideal fluid which obeys the first law of thermodynamics; thus it satisfies the ordinary energy-momentum conservation or continuity equation.

  13. Generalized massive gravity in AdS{sub 3} spacetime

    SciTech Connect (OSTI)

    Liu Yan; Sun Yawen [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P. O. Box 2735, Beijing 100190 (China)

    2009-06-15T23:59:59.000Z

    In this note we investigate the generalized massive gravity in asymptotically AdS{sub 3} spacetime by combining the two mass terms of topological massive gravity and new massive gravity theory. We study the linearized excitations around the AdS{sub 3} background and find that at a specific value of a certain combination of the two mass parameters (chiral line), one of the massive graviton solutions becomes the left-moving massless mode. It is shown that the theory is chiral at this line under Brown-Henneaux boundary condition. Because of this degeneration of the gravitons the new log solution which has a logarithmic asymptotic behavior is also a solution to this gravity theory at the chiral line. The log boundary condition which was proposed to accommodate this log solution is proved to be consistent at this chiral line. The resulting theory is no longer chiral except at a special point on the chiral line, where another new solution with log-square asymptotic behavior exists. At this special point, we prove that a new kind of boundary condition called log-square boundary condition, which accommodates this new solution, can be consistent.

  14. Monitoring Massive Appliances by a Minimal Number of Smart Meters

    E-Print Network [OSTI]

    Wang, Yongcai

    56 Monitoring Massive Appliances by a Minimal Number of Smart Meters YONGCAI WANG, XIAOHONG HAO. This article presents a framework for deploying a minimal number of smart meters to accurately track the ON of required smart meters is studied by an entropy-based approach, which qualifies the impact of meter

  15. THE FORMATION AND EVOLUTION OF THE FIRST MASSIVE BLACK HOLES

    E-Print Network [OSTI]

    Wurtele, Jonathan

    @astron.berkeley.edu Abstract The first massive astrophysical black holes likely formed at high redshifts (z > 10 (Eddington) luminosity, and converts mass to radiation with an efficiency of = Mc2 /LEdd 10%) and using to link the evolution of quasars with that of dark matter halos condensing in a cold dark matter (CDM

  16. X-ray Emission from Massive Stars David Cohen

    E-Print Network [OSTI]

    Cohen, David

    X-ray Emission from Massive Stars David Cohen Department of Physics and Astronomy Swarthmore University, Oct. 13, 2005 astro.swarthmore.edu/~cohen/ #12;Outline 1. What you need to know: a. X-rays from the Sun - magnetic activity, x-ray spectra b. Hot stars c. Radiation-driven winds and the Doppler shift d

  17. Sequential and parallel algorithms for minimum cost parallel decomposition of finite state machines

    E-Print Network [OSTI]

    Shelke, Rajendra Ram

    1992-01-01T23:59:59.000Z

    form a lattice, where each node in the lattice has a cost associated with it. An algorithm to build the lattice is presented. Also to find the best pos- sible parallel decomposition, an optimal cost algorithm is proposed. Sequential snd parallel.... The OSI Reference Model C. Bottlenecks in Communication Protocols D. High Speed Protocols E. High-Speed Implementations F. Structure of the Thesis THEORETICAL BACKGROUND A. Set Theory . B. Partially Ordered Sets and Lattices C. Sequential Machines...

  18. Implementation of a cell-wise Block-Gauss-Seidel iterative method for SN transport on a hybrid parallel computer architecture

    SciTech Connect (OSTI)

    Rosa, Massimiliano [Los Alamos National Laboratory; Warsa, James S [Los Alamos National Laboratory; Perks, Michael [Los Alamos National Laboratory

    2010-12-14T23:59:59.000Z

    We have implemented a cell-wise, block-Gauss-Seidel (bGS) iterative algorithm, for the solution of the S{sub n} transport equations on the Roadrunner hybrid, parallel computer architecture. A compute node of this massively parallel machine comprises AMD Opteron cores that are linked to a Cell Broadband Engine{trademark} (Cell/B.E.). LAPACK routines have been ported to the Cell/B.E. in order to make use of its parallel Synergistic Processing Elements (SPEs). The bGS algorithm is based on the LU factorization and solution of a linear system that couples the fluxes for all S{sub n} angles and energy groups on a mesh cell. For every cell of a mesh that has been parallel decomposed on the higher-level Opteron processors, a linear system is transferred to the Cell/B.E. and the parallel LAPACK routines are used to compute a solution, which is then transferred back to the Opteron, where the rest of the computations for the S{sub n} transport problem take place. Compared to standard parallel machines, a hundred-fold speedup of the bGS was observed on the hybrid Roadrunner architecture. Numerical experiments with strong and weak parallel scaling demonstrate the bGS method is viable and compares favorably to full parallel sweeps (FPS) on two-dimensional, unstructured meshes when it is applied to optically thick, multi-material problems. As expected, however, it is not as efficient as FPS in optically thin problems.

  19. Instruction sets for Parallel Random Access Machines

    SciTech Connect (OSTI)

    Trahan, J.L.

    1988-01-01T23:59:59.000Z

    The computational powers of time-bounded Parallel Random Access Machines (PRAMs) with different instruction sets are compared. A basic PRAM can perform the following operations in unit-time: addition, subtraction, Boolean operations, comparisons, and indirect addressing. Multiple processors may concurrently read and concurrently write a single cell. This thesis establishes that the class of languages accepted in polynomial time on a PRAM(*, {up arrow}, {down arrow}) contains the class of languages accepted in exponential time on a nondeterministic Turing machine (NEXPTIME) and is contained in the class of languages accepted in exponential space on a Turing machine. Efficient simulations are presented of PRAMs with enhanced instruction sets by sequential RAMs with the same instruction sets; also simulations of probabilistic PRAMs by deterministic PRAMs, using parallelism to replace randomness. Also given are simulations of PRAM(op)s by PRAMs, where both the simulated machine and the simulating machine are exclusive-read, exclusive-write machines.

  20. Locating hardware faults in a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J.; Megerian, Mark G.; Ratterman, Joseph D.; Smith, Brian E.

    2010-04-13T23:59:59.000Z

    Locating hardware faults in a parallel computer, including defining within a tree network of the parallel computer two or more sets of non-overlapping test levels of compute nodes of the network that together include all the data communications links of the network, each non-overlapping test level comprising two or more adjacent tiers of the tree; defining test cells within each non-overlapping test level, each test cell comprising a subtree of the tree including a subtree root compute node and all descendant compute nodes of the subtree root compute node within a non-overlapping test level; performing, separately on each set of non-overlapping test levels, an uplink test on all test cells in a set of non-overlapping test levels; and performing, separately from the uplink tests and separately on each set of non-overlapping test levels, a downlink test on all test cells in a set of non-overlapping test levels.

  1. Nonlinear parallel momentum transport in strong turbulence

    E-Print Network [OSTI]

    Wang, Lu; Diamond, P H

    2015-01-01T23:59:59.000Z

    Most existing theoretical studies of momentum transport focus on calculating the Reynolds stress based on quasilinear theory, without considering the \\emph{nonlinear} momentum flux-$$. However, a recent experiment on TORPEX found that the nonlinear toroidal momentum flux induced by blobs makes a significant contribution as compared to the Reynolds stress [Labit et al., Phys. Plasmas {\\bf 18}, 032308 (2011)]. In this work, the nonlinear parallel momentum flux in strong turbulence is calculated by using three dimensional Hasegawa-Mima equation. It is shown that nonlinear diffusivity is smaller than quasilinear diffusivity from Reynolds stress. However, the leading order nonlinear residual stress can be comparable to the quasilinear residual stress, and so could be important to intrinsic rotation in tokamak edge plasmas. A key difference from the quasilinear residual stress is that parallel fluctuation spectrum asymmetry is not required for nonlinear residual stress.

  2. Parallel machine architecture for production rule systems

    DOE Patents [OSTI]

    Allen, Jr., John D. (Knoxville, TN); Butler, Philip L. (Knoxville, TN)

    1989-01-01T23:59:59.000Z

    A parallel processing system for production rule programs utilizes a host processor for storing production rule right hand sides (RHS) and a plurality of rule processors for storing left hand sides (LHS). The rule processors operate in parallel in the recognize phase of the system recognize -Act Cycle to match their respective LHS's against a stored list of working memory elements (WME) in order to find a self consistent set of WME's. The list of WME is dynamically varied during the Act phase of the system in which the host executes or fires rule RHS's for those rules for which a self-consistent set has been found by the rule processors. The host transmits instructions for creating or deleting working memory elements as dictated by the rule firings until the rule processors are unable to find any further self-consistent working memory element sets at which time the production rule system is halted.

  3. Parallel Web Scripting with Reactive Constraints Thibaud Hottelier

    E-Print Network [OSTI]

    Bodik, Rastisla

    Parallel Web Scripting with Reactive Constraints Thibaud Hottelier James Ide Doug Kimelman Ras Bodik Electrical Engineering and Computer Sciences University of California at Berkeley Technical Report to lists, requires prior specific permission. #12;Parallel Web Scripting with Reactive Constraints Thibaud

  4. Parallel and Distributed Multi-Algorithm Circuit Simulation

    E-Print Network [OSTI]

    Dai, Ruicheng

    2012-10-19T23:59:59.000Z

    With the proliferation of parallel computing, parallel computer-aided design (CAD) has received significant research interests. Transient transistor-level circuit simulation plays an important role in digital/analog circuit design and verification...

  5. Parallel Solutions of Partial Differential Equations with Adaptive Multigrid Methods

    E-Print Network [OSTI]

    Wieners, Christian

    Parallel Solutions of Partial Differential Equations with Adaptive Multigrid Methods results for the solution of partial differential equations based on the software platform UG. State/coarsening, robust parallel multigrid methods, various dis­ cretizations, dynamic load balancing, mapping and grid

  6. A Taxonomy of Parallel Prefix Networks David Harris

    E-Print Network [OSTI]

    Harris, David Money

    A Taxonomy of Parallel Prefix Networks David Harris Harvey Mudd College / Sun Microsystems Laboratories 301 E. Twelfth St. Claremont, CA 91711 David_Harris@hmc.edu Abstract - Parallel prefix networks

  7. Data Parallel SwitchLevel Simulation \\Lambda Randal E. Bryant

    E-Print Network [OSTI]

    Bryant, Randal E.

    Data Parallel Switch­Level Simulation \\Lambda Randal E. Bryant Computer Science Department Carnegie the bit­level paral­ lelism inherent in conventional machine operations. Bryant---Data Parallel Simulation

  8. Shape-based Cost Analysis of Skeletal Parallel Programs 

    E-Print Network [OSTI]

    Hayashi, Yasushi

    This work presents an automatic cost-analysis system for an implicitly parallel skeletal programming language. Although deducing interesting dynamic characteristics of parallel programs (and in particular, run time) is ...

  9. Parallel algorithms and architectures for low power video decoding

    E-Print Network [OSTI]

    Sze, Vivienne

    2010-01-01T23:59:59.000Z

    Parallelism coupled with voltage scaling is an effective approach to achieve high processing performance with low power consumption. This thesis presents parallel architectures and algorithms designed to deliver the power ...

  10. ParCAT: Parallel Climate Analysis Toolkit

    SciTech Connect (OSTI)

    Smith, Brian E [ORNL; Steed, Chad A [ORNL; Shipman, Galen M [ORNL; Ricciuto, Daniel M [ORNL; Thornton, Peter E [ORNL; Wehner, Michael [Lawrence Berkeley National Laboratory (LBNL); Williams, Dean N. [Lawrence Livermore National Laboratory (LLNL)

    2013-01-01T23:59:59.000Z

    Climate science is employing increasingly complex models and simulations to analyze the past and predict the future of Earth s climate. This growth in complexity is creating a widening gap between the data being produced and the ability to analyze the datasets. Parallel computing tools are necessary to analyze, compare, and interpret the simulation data. The Parallel Climate Analysis Toolkit (ParCAT) provides basic tools to efficiently use parallel computing techniques to make analysis of these datasets manageable. The toolkit provides the ability to compute spatio-temporal means, differences between runs or differences between averages of runs, and histograms of the values in a data set. ParCAT is implemented as a command-line utility written in C. This allows for easy integration in other tools and allows for use in scripts. This also makes it possible to run ParCAT on many platforms from laptops to supercomputers. ParCAT outputs NetCDF files so it is compatible with existing utilities such as Panoply and UV-CDAT. This paper describes ParCAT and presents results from some example runs on the Titan system at ORNL.

  11. Xyce parallel electronic simulator : reference guide.

    SciTech Connect (OSTI)

    Mei, Ting; Rankin, Eric Lamont; Thornquist, Heidi K.; Santarelli, Keith R.; Fixel, Deborah A.; Coffey, Todd Stirling; Russo, Thomas V.; Schiek, Richard Louis; Warrender, Christina E.; Keiter, Eric Richard; Pawlowski, Roger Patrick

    2011-05-01T23:59:59.000Z

    This document is a reference guide to the Xyce Parallel Electronic Simulator, and is a companion document to the Xyce Users Guide. The focus of this document is (to the extent possible) exhaustively list device parameters, solver options, parser options, and other usage details of Xyce. This document is not intended to be a tutorial. Users who are new to circuit simulation are better served by the Xyce Users Guide. The Xyce Parallel Electronic Simulator has been written to support, in a rigorous manner, the simulation needs of the Sandia National Laboratories electrical designers. It is targeted specifically to run on large-scale parallel computing platforms but also runs well on a variety of architectures including single processor workstations. It also aims to support a variety of devices and models specific to Sandia needs. This document is intended to complement the Xyce Users Guide. It contains comprehensive, detailed information about a number of topics pertinent to the usage of Xyce. Included in this document is a netlist reference for the input-file commands and elements supported within Xyce; a command line reference, which describes the available command line arguments for Xyce; and quick-references for users of other circuit codes, such as Orcad's PSpice and Sandia's ChileSPICE.

  12. On Optimal Slicing of Parallel Programs Markus Muller-Olm

    E-Print Network [OSTI]

    Müller-Olm, Markus

    On Optimal Slicing of Parallel Programs Markus M¨uller-Olm Universit¨at Dortmund, FB Informatik, LS

  13. A parallel interior point decomposition algorithm for block angular ...

    E-Print Network [OSTI]

    2008-05-24T23:59:59.000Z

    a parallel and distributed high performance computing environment. We compare our. MPI (Message Passing Interface) implementation of the decomposition ...

  14. Mass dependence of the vacuum energy density in the massive Schwinger model

    E-Print Network [OSTI]

    Taekoon Lee

    2007-03-09T23:59:59.000Z

    The vacuum energy density of the massive Schwinger model is shown to be not power expandable in the fermion mass.

  15. Architecture independent parallel binomial tree option price valuations

    E-Print Network [OSTI]

    Gerbessiotis, Alexandros V.

    Architecture independent parallel binomial tree option price valuations Alexandros V. Gerbessiotis­02 #12; Architecture independent parallel binomial tree option price valuations Alexandros V in American or European­style option valuations can be performed in parallel in the binomial­tree model

  16. Comparing the Parix and PVM parallel programming environments

    E-Print Network [OSTI]

    Amsterdam, Universiteit van

    1 Comparing the Parix and PVM parallel programming environments A.G. Hoekstra, P.M.A. Sloot, and L Genericity of parallel programming environments, enabling development of portable parallel programs environments are important issues if a choice between programming environments has to be made. We propose

  17. A Generalisation of Indexing for Parallel Document Search

    E-Print Network [OSTI]

    Graham, Nick

    A Generalisation of Indexing for Parallel Document Search D.B. Skillicorn skill Science Queen's University Kingston, Ontario K7L 3N6 Document prepared March 21, 1995 Copyright c fl1995 D.B. Skillicorn #12; A Generalisation of Indexing for Parallel Document Search Abstract Parallelism is useful

  18. A Generalisation of Indexing for Parallel Document Search

    E-Print Network [OSTI]

    Graham, Nick

    A Generalisation of Indexing for Parallel Document Search D.B. Skillicorn skill Science Queen's University Kingston, Ontario K7L 3N6 Document prepared March 21, 1995 Copyright c 1995 D.B. Skillicorn #12;A Generalisation of Indexing for Parallel Document Search Abstract Parallelism is useful

  19. Making Nested Parallel Transactions Practical using Lightweight Hardware Support

    E-Print Network [OSTI]

    Kozyrakis, Christos

    Making Nested Parallel Transactions Practical using Lightweight Hardware Support Woongki Baek possible performance, TM must support the nested parallelism available in real-world applications and sup- ported by popular programming models. A few recent papers have proposed support for nested parallelism

  20. Equivalency-processing parallel photonic integrated circuit EP3

    E-Print Network [OSTI]

    Louri, Ahmed

    Equivalency-processing parallel photonic integrated circuit EP3 IC : equivalence search module present an optoelectronic module called the equivalency-processing parallel photonic integrated circuit EP3 IC that is created specifically to implement high-speed parallel equivalence searches i

  1. Mono inverter Multi parallel PMSM -Structure and Control strategy

    E-Print Network [OSTI]

    Boyer, Edmond

    Mono inverter Multi parallel PMSM - Structure and Control strategy Damien Bidarta , Maria Pietrzak a new and original Mono inverter Multi parallel Permanent Magnet Synchronous Motor (PMSM) system. Experimental results are given for a system with 2 PMSM plugged in parallel. The proposed solution can however

  2. Cloud Futures Workshop 2010 Cloud Computing Support for Massively Social Gaming Alexandru Iosup

    E-Print Network [OSTI]

    Iosup, Alexandru

    1 Cloud Futures Workshop 2010 ­ Cloud Computing Support for Massively Social Gaming Alexandru Iosup Pierre (Vrije U.). Cloud Computing Support for Massively Social Gaming (Rain for the Thirsty) #12;Cloud Futures Workshop 2010 ­ Cloud Computing Support for Massively Social Gaming 2 Intermezzo: Tips on how

  3. PARALLEL COMPUTING 2013 (ParCo2013) 10 13 September 2013

    E-Print Network [OSTI]

    Cengarle, María Victoria

    Energy Efficiency. The parallel computing aspects should be emphasized. Section 2: Software parallel code #12;2 Testing and debugging techniques and tools Best practices of parallel computing

  4. Lectures on BRS invariance for massive boson fields

    E-Print Network [OSTI]

    Jose M. Gracia-Bondia

    2010-04-26T23:59:59.000Z

    These notes correspond to lectures given at the Villa de Leyva Summer School in Colombia (July 2007). Our main purpose in this short course on BRS invariance of gauge theories is to illuminate corners of the theory left in the shade by standard treatments. The plan is as follows. First a review of Utiyama's "general gauge theory". Promptly we find a counterexample to it in the shape of the massive spin-1 Stueckelberg gauge field. This is not fancy, as the massive case is the most natural one to introduce BRS invariance in the context of free quantum fields. Mathematically speaking, the first part of the course uses Utiyama's notation, and thus has the flavour and non-intrinsic notation of standard physics textbooks. Next we deal with boson fields on Fock space and BRS invariance in connection with the existence of Krein operators; the attending rigour points are then addressed.

  5. Vacua and instantons of ghost-free massive gravity

    E-Print Network [OSTI]

    Minjoon Park; Lorenzo Sorbo

    2012-12-12T23:59:59.000Z

    Recently discovered models of ghost-free massive gravity and bigravity are characterized by a non-trivial potential that gives rise to a rich vacuum structure. We review maximally symmetric vacua of the de Rham-Gabadadze-Tolley (dRGT) massive gravity and of the Hassan-Rosen (HR) bigravity, and discuss their perturbative stability. In particular, we discuss perturbations about self-accelerating vacua in HR bigravity, and argue that, analogously to what was found in the case of dRGT gravity, some of them contain strongly coupled modes. We then show that it is impossible to construct regular instantons connecting different classically stable vacua of dRGT gravity without violating energy conservation or the null energy condition.

  6. Secular stability and instability in stellar systems surrounding massive objects

    E-Print Network [OSTI]

    Scott Tremaine

    2004-12-13T23:59:59.000Z

    We examine the stability of a low-mass stellar system surrounding a massive central object. Examples of such systems include the centers of galaxies or star clusters containing a massive black hole, and the Oort comet cloud. If the self-gravity of the stellar system is the dominant non-Keplerian force, such systems may be subject to slowly growing (secular) lopsided instabilities. Stability to secular modes is largely determined by the dependence of the distribution function F on angular momentum J. If dF/dJ 0, as is expected if there is a loss cone at low angular momentum, all spherical systems in which F=0 at J=0 (an empty loss cone) are only neutrally stable, and flattened, non-rotating systems are generally unstable. These results suggest that secular instabilities may dominate the structure and evolution of the stellar systems in the centers of galaxies.

  7. Infrared Singularities and Soft Gluon Resummation with Massive Partons

    E-Print Network [OSTI]

    A. Ferroglia; M. Neubert; B. D. Pecjak; L. L. Yang

    2010-06-24T23:59:59.000Z

    Infrared divergences of QCD scattering amplitudes can be derived from an anomalous dimension matrix, which is also an essential ingredient for the resummation of large logarithms due to soft gluon emissions. We report a recent analytical calculation of the anomalous dimension matrix with both massless and massive partons at two-loop level, which describes the two-loop infrared singularities of any scattering amplitudes with an arbitrary number of massless and massive partons, and also enables soft gluon resummation at next-to-next-to-leading-logarithmic order. As an application, we calculate the infrared poles in the q qbar -> t tbar and gg -> t tbar scattering amplitudes at two-loop order.

  8. A Grid of FASTWIND NLTE Model Atmospheres of Massive Stars

    E-Print Network [OSTI]

    K. Lefever; J. Puls; C. Aerts

    2006-09-22T23:59:59.000Z

    In the last few years our knowledge of the physics of massive stars has improved tremendously. However, further investigations are still needed, especially regarding accurate calibrations of their fundamental parameters. To this end, we have constructed a comprehensive grid of NLTE model atmospheres and corresponding synthetic spectra in the massive star domain. The grid covers the complete B type spectral range, extended to late O on the hot side and early A on the cool side, from supergiants to dwarfs and from weak stellar winds to very strong ones. It has been calculated with the latest version of the FASTWIND code. The analysis of an extensive sample of OB stars in the framework of the COROT space mission will lead to accurate calibrations of effective temperatures, gravities, mass loss rates etc. This paper contains a detailed description of the grid, which has been baptised as BSTAR06 and which will be available for further research in the near future.

  9. A symmetric approach to the massive nonlinear sigma model

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

    Ferrari, Ruggero

    2011-09-28T23:59:59.000Z

    In the present paper we extend to the massive case the procedure of divergences subtraction, previously introduced for the massless nonlinear sigma model (D = 4). Perturbative expansion in the number of loops is successfully constructed. The resulting theory depends on the Spontaneous Symmetry Breaking parameter v, on the mass m and on the radiative correction parameter ?. Fermions are not considered in the present work. SU(2)?­SU(2) is the group used.

  10. From massive gravity to dark matter density II

    E-Print Network [OSTI]

    G. Scharf

    2009-02-18T23:59:59.000Z

    As previously observed the massless limit of massive gravity leads to a modification of general relativity. Here we study spherically symmetric solutions of the modified field equations which contain normal matter together with a dark energy density. If the dark density profile is assumed to be known, the whole problem is reduced to a linear first order differential equation which can be solved by quadratures.

  11. On the Solutions of Einstein Equations with Massive Point Source

    E-Print Network [OSTI]

    P. P. Fiziev

    2004-12-30T23:59:59.000Z

    We show that Einstein equations are compatible with the presence of massive point particles and find corresponding two parameter family of their solutions which depends on the bare mechanical mass $M_0>0$ and the Keplerian mass $M

  12. Double Diffusion in Enclosure Bounded by Massive and Volatilizing Walls

    E-Print Network [OSTI]

    Liu, D.; Tang, G.; Zhao, F.

    2006-01-01T23:59:59.000Z

    ICEBO2006, Shenzhen, China Maximize Comfort: Temperature, Humidity and IAQ Vol.I-6-5 Double Diffusion in Enclosure Bounded by Massive and Volatilizing Walls Di Liu Guangfa Tang Fuyun Zhao Doctoral Professor.... INTRODUCTION It has become evident that building products are major contributors to the pollution of the indoor air environment with volatile organic compounds (VOCs) [1]. The indoor airflow and temperature distributions also have influence on the emission...

  13. Black holes in Born-Infeld extended new massive gravity

    SciTech Connect (OSTI)

    Ghodsi, Ahmad; Yekta, Davood Mahdavian [Department of Physics, Ferdowsi University of Mashhad, P.O. Box 1436, Mashhad (Iran, Islamic Republic of)

    2011-05-15T23:59:59.000Z

    In this paper we find different types of black holes for the Born-Infeld extended new massive gravity. Our solutions include (un)charged warped (anti-)de Sitter black holes for four and six derivative expanded action. We also look at the black holes in unexpanded Born-Infeld action. In each case we calculate the entropy, angular momentum and mass of the black holes. We also find the central charges for the conformal field theory duals.

  14. Static, massive fields and vacuum polarization potential in Rindler space

    E-Print Network [OSTI]

    B. Linet

    1997-04-03T23:59:59.000Z

    In Rindler space, we determine in terms of special functions the expression of the static, massive scalar or vector field generated by a point source. We find also an explicit integral expression of the induced electrostatic potential resulting from the vacuum polarization due to an electric charge at rest in the Rindler coordinates. For a weak acceleration, we give then an approximate expression in the Fermi coordinates associated with the uniformly accelerated observer.

  15. Which Massive stars are Gamma-Ray Burst Progenitors?

    E-Print Network [OSTI]

    Jelena Petrovic; Norbert Langer; Sung-Chul Yoon; Alexander Heger

    2005-04-11T23:59:59.000Z

    The collapsar model for gamma-ray bursts requires three essential ingredients: a massive core, removal of the hydrogen envelope, and enough angular momentum in the core. We study current massive star evolution models of solar metallicity to determine which massive star physics is capable of producing these ingredients. In particular, we investigate the role of hydrodynamic and magnetic internal angular momentum transport and binary mass and angular momentum transfer. We follow the evolution of rotating single stars and of binary systems that include rotational processes for both stars. Neglecting magnetic fields, we show that the cores of massive single stars can maintain a high specific angular momentum when evolved with the assumption that mean molecular weight gradients suppress rotational mixing processes. In binary systems that undergo mass transfer during core hydrogen burning the mass receiving star accretes large amounts of high angular momentum material, leading to a spin-up of the core. We find, however, that this merely compensates for the tidal angular momentum loss due to spin-orbit coupling, which leads to synchronous rotation before the mass transfer event. Therefore the resulting cores do not rotate faster than in single stars. We also present models that include magnetic fields generated by differential rotation and we consider the internal angular momentum transport by magnetic torques. We investigate the capability of magnetic torques to efficiently pump angular momentum into the cores of accreting stars. Despite our finding that this mechanism works, the magnetic coupling of core and envelope after the accreting star ends core hydrogen burning leads to slower rotation than in the non-magnetic case.

  16. Filaments, Collapse and Outflows in Massive Star Formation

    E-Print Network [OSTI]

    Robi Banerjee; Ralph E. Pudritz

    2008-07-04T23:59:59.000Z

    We present results from our numerical simulations of collapsing massive molecular cloud cores. These numerical calculations show that massive stars assemble quickly with mass accretion rates exceeding 10^-3 Msol/yr and confirm that the mass accretion during the collapsing phase is much more efficient than predicted by selfsimilar collapse solutions, dM/dt ~ c^3/G. We find that during protostellar assembly out of a non-turbulent core, the mass accretion reaches 20 - 100 c^3/G. Furthermore, we explore the self-consistent structure of bipolar outflows that are produced in our three dimensional magnetized collapse simulations. These outflows produce cavities out of which radiation pressure can be released, thereby reducing the limitations on the final mass of massive stars formed by gravitational collapse. Additional enhancement of the mass accretion rate comes from accretion along filaments that are built up by supersonic turbulent motions. Our numerical calculations of collapsing turbulent cores result in mass accretion rates as high as 10^-2 Msol/yr.

  17. The Massive Star Population of Cygnus OB2

    E-Print Network [OSTI]

    Wright, Nicholas J; Mohr-Smith, Michael

    2015-01-01T23:59:59.000Z

    We have compiled a significantly updated and comprehensive census of massive stars in the nearby Cygnus OB2 association by gathering and homogenising data from across the literature. The census contains 169 primary OB stars, including 52 O-type stars and 3 Wolf-Rayet stars. Spectral types and photometry are used to place the stars in a Hertzprung-Russell diagram, which is compared to both non-rotating and rotating stellar evolution models, from which stellar masses and ages are calculated. The star formation history and mass function of the association are assessed, and both are found to be heavily influenced by the evolution of the most massive stars to their end states. We find that the mass function of the most massive stars is consistent with a `universal' power-law slope of Gamma = 1.3. The age distribution inferred from stellar evolutionary models with rotation and the mass function suggest the majority of star formation occurred more or less continuously between 1 and 7 Myr ago, in agreement with studi...

  18. Three dimensional Casimir piston for massive scalar fields

    E-Print Network [OSTI]

    S. C. Lim; L. P. Teo

    2008-07-23T23:59:59.000Z

    We consider Casimir force acting on a three dimensional rectangular piston due to a massive scalar field subject to periodic, Dirichlet and Neumann boundary conditions. Exponential cut-off method is used to derive the Casimir energy in the interior region and the exterior region separated by the piston. It is shown that the divergent term of the Casimir force acting on the piston due to the interior region cancels with that due to the exterior region, thus render a finite well-defined Casimir force acting on the piston. Explicit expressions for the total Casimir force acting on the piston is derived, which show that the Casimir force is always attractive for all the different boundary conditions considered. As a function of a -- the distance from the piston to the opposite wall, it is found that the magnitude of the Casimir force behaves like $1/a^4$ when $a\\to 0^+$ and decays exponentially when $a\\to \\infty$. Moreover, the magnitude of the Casimir force is always a decreasing function of a. On the other hand, passing from massless to massive, we find that the effect of the mass is insignificant when a is small, but the magnitude of the force is decreased for large a in the massive case.

  19. Three-dimensional Casimir piston for massive scalar fields

    SciTech Connect (OSTI)

    Lim, S.C. [Faculty of Engineering, Multimedia University, Jalan Multimedia, Cyberjaya 63100, Selangor Darul Ehsan (Malaysia)], E-mail: sclim@mmu.edu.my; Teo, L.P. [Faculty of Information Technology, Multimedia University, Jalan Multimedia, Cyberjaya 63100, Selangor Darul Ehsan (Malaysia)], E-mail: lpteo@mmu.edu.my

    2009-08-15T23:59:59.000Z

    We consider Casimir force acting on a three-dimensional rectangular piston due to a massive scalar field subject to periodic, Dirichlet and Neumann boundary conditions. Exponential cut-off method is used to derive the Casimir energy. It is shown that the divergent terms do not contribute to the Casimir force acting on the piston, thus render a finite well-defined Casimir force acting on the piston. Explicit expressions for the total Casimir force acting on the piston is derived, which show that the Casimir force is always attractive for all the different boundary conditions considered. As a function of a - the distance from the piston to the opposite wall, it is found that the magnitude of the Casimir force behaves like 1/a{sup 4} when a{yields}0{sup +} and decays exponentially when a{yields}{infinity}. Moreover, the magnitude of the Casimir force is always a decreasing function of a. On the other hand, passing from massless to massive, we find that the effect of the mass is insignificant when a is small, but the magnitude of the force is decreased for large a in the massive case.

  20. Einstein Gravity, Massive Gravity, Multi-Gravity and Nonlinear Realizations

    E-Print Network [OSTI]

    Garrett Goon; Kurt Hinterbichler; Austin Joyce; Mark Trodden

    2014-12-18T23:59:59.000Z

    The existence of a ghost free theory of massive gravity begs for an interpretation as a Higgs phase of General Relativity. We revisit the study of massive gravity as a Higgs phase. Absent a compelling microphysical model of spontaneous symmetry breaking in gravity, we approach this problem from the viewpoint of nonlinear realizations. We employ the coset construction to search for the most restrictive symmetry breaking pattern whose low energy theory will both admit the de Rham--Gabadadze--Tolley (dRGT) potentials and nonlinearly realize every symmetry of General Relativity, thereby providing a new perspective from which to build theories of massive gravity. In addition to the known ghost-free terms, we find a novel parity violating interaction which preserves the constraint structure of the theory, but which vanishes on the normal branch of the theory. Finally, the procedure is extended to the cases of bi-gravity and multi-vielbein theories. Analogous parity violating interactions exist here, too, and may be non-trivial for certain classes of multi-metric theories.

  1. Probing Massive Stars Around Gamma-Ray Burst Progenitors

    E-Print Network [OSTI]

    Lu, Wenbin; Smoot, George F

    2015-01-01T23:59:59.000Z

    Long Gamma-Ray Bursts (GRBs) are produced by ultra-relativistic jets launched from core collapse of massive stars. Most massive stars form in binaries and/or in star clusters, which means that there may be a significant external photon field (EPF) around the GRB progenitor. We calculate the inverse-Compton scattering of EPF by the hot electrons in the GRB jet. Three possible cases of EPFs are considered: the progenitor is (I) in a massive binary system, (II) surrounded by a Wolf-Rayet-star wind, and (III) in a dense star cluster. Typical luminosities of 10^47 - 10^50 erg/s in the 10 - 100 GeV band are expected, depending on the stellar luminosity, binary separation (I), wind mass loss rate (II), stellar number density (III), etc. We calculate the lightcurve and spectrum in each case, taking fully into account the equal-arrival time surfaces and possible pair-production absorption with the prompt gamma-rays. Observations can put constraints on the existence of such EPFs (and hence on the nature of GRB progenit...

  2. Parallelizing AT with MatlabMPI

    SciTech Connect (OSTI)

    Li, Evan Y.; /Brown U. /SLAC

    2011-06-22T23:59:59.000Z

    The Accelerator Toolbox (AT) is a high-level collection of tools and scripts specifically oriented toward solving problems dealing with computational accelerator physics. It is integrated into the MATLAB environment, which provides an accessible, intuitive interface for accelerator physicists, allowing researchers to focus the majority of their efforts on simulations and calculations, rather than programming and debugging difficulties. Efforts toward parallelization of AT have been put in place to upgrade its performance to modern standards of computing. We utilized the packages MatlabMPI and pMatlab, which were developed by MIT Lincoln Laboratory, to set up a message-passing environment that could be called within MATLAB, which set up the necessary pre-requisites for multithread processing capabilities. On local quad-core CPUs, we were able to demonstrate processor efficiencies of roughly 95% and speed increases of nearly 380%. By exploiting the efficacy of modern-day parallel computing, we were able to demonstrate incredibly efficient speed increments per processor in AT's beam-tracking functions. Extrapolating from prediction, we can expect to reduce week-long computation runtimes to less than 15 minutes. This is a huge performance improvement and has enormous implications for the future computing power of the accelerator physics group at SSRL. However, one of the downfalls of parringpass is its current lack of transparency; the pMatlab and MatlabMPI packages must first be well-understood by the user before the system can be configured to run the scripts. In addition, the instantiation of argument parameters requires internal modification of the source code. Thus, parringpass, cannot be directly run from the MATLAB command line, which detracts from its flexibility and user-friendliness. Future work in AT's parallelization will focus on development of external functions and scripts that can be called from within MATLAB and configured on multiple nodes, while expending minimal communication overhead with the integrated MATLAB library.

  3. Carbothermic reduction with parallel heat sources

    DOE Patents [OSTI]

    Troup, Robert L. (Murrysville, PA); Stevenson, David T. (Washington Township, Washington County, PA)

    1984-12-04T23:59:59.000Z

    Disclosed are apparatus and method of carbothermic direct reduction for producing an aluminum alloy from a raw material mix including aluminum oxide, silicon oxide, and carbon wherein parallel heat sources are provided by a combustion heat source and by an electrical heat source at essentially the same position in the reactor, e.g., such as at the same horizontal level in the path of a gravity-fed moving bed in a vertical reactor. The present invention includes providing at least 79% of the heat energy required in the process by the electrical heat source.

  4. Parallel heater system for subsurface formations

    DOE Patents [OSTI]

    Harris, Christopher Kelvin (Houston, TX); Karanikas, John Michael (Houston, TX); Nguyen, Scott Vinh (Houston, TX)

    2011-10-25T23:59:59.000Z

    A heating system for a subsurface formation is disclosed. The system includes a plurality of substantially horizontally oriented or inclined heater sections located in a hydrocarbon containing layer in the formation. At least a portion of two of the heater sections are substantially parallel to each other. The ends of at least two of the heater sections in the layer are electrically coupled to a substantially horizontal, or inclined, electrical conductor oriented substantially perpendicular to the ends of the at least two heater sections.

  5. Partitioning sparse rectangular matrices for parallel processing

    SciTech Connect (OSTI)

    Kolda, T.G.

    1998-05-01T23:59:59.000Z

    The authors are interested in partitioning sparse rectangular matrices for parallel processing. The partitioning problem has been well-studied in the square symmetric case, but the rectangular problem has received very little attention. They will formalize the rectangular matrix partitioning problem and discuss several methods for solving it. They will extend the spectral partitioning method for symmetric matrices to the rectangular case and compare this method to three new methods -- the alternating partitioning method and two hybrid methods. The hybrid methods will be shown to be best.

  6. Parallel State Estimation Assessment with Practical Data

    SciTech Connect (OSTI)

    Chen, Yousu; Jin, Shuangshuang; Rice, Mark J.; Huang, Zhenyu

    2014-10-31T23:59:59.000Z

    This paper presents a full-cycle parallel state estimation (PSE) implementation using a preconditioned conjugate gradient algorithm. The developed code is able to solve large-size power system state estimation within 5 seconds using real-world data, comparable to the Supervisory Control And Data Acquisition (SCADA) rate. This achievement allows the operators to know the system status much faster to help improve grid reliability. Case study results of the Bonneville Power Administration (BPA) system with real measurements are presented. The benefits of fast state estimation are also discussed.

  7. Optimize Parallel Pumping Systems | Department of Energy

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:Year in3.pdfEnergyDepartment ofOil's Impact on Our National- 2013EnergyOptimize Parallel

  8. PISTON (Portable Data Parallel Visualization and Analysis)

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 - September 2006 The 2002OpticsPeriodical:RockyPISTON (Portable Data Parallel

  9. Parallel Volume-Rendering Algorithm Performance on Mesh-Connected Multicomputers

    E-Print Network [OSTI]

    Shahabi, Cyrus

    Parallel Volume-Rendering Algorithm Performance on Mesh-Connected Multicomputers Ulrich Neumann rendering algorithms. This issue has not been addressed in papers describing particular parallel implementations, but is pertinent to anyone dc- signing or implementing parallel rendering algorithms. Parallel

  10. Switch for serial or parallel communication networks

    DOE Patents [OSTI]

    Crosette, D.B.

    1994-07-19T23:59:59.000Z

    A communication switch apparatus and a method for use in a geographically extensive serial, parallel or hybrid communication network linking a multi-processor or parallel processing system has a very low software processing overhead in order to accommodate random burst of high density data. Associated with each processor is a communication switch. A data source and a data destination, a sensor suite or robot for example, may also be associated with a switch. The configuration of the switches in the network are coordinated through a master processor node and depends on the operational phase of the multi-processor network: data acquisition, data processing, and data exchange. The master processor node passes information on the state to be assumed by each switch to the processor node associated with the switch. The processor node then operates a series of multi-state switches internal to each communication switch. The communication switch does not parse and interpret communication protocol and message routing information. During a data acquisition phase, the communication switch couples sensors producing data to the processor node associated with the switch, to a downlink destination on the communications network, or to both. It also may couple an uplink data source to its processor node. During the data exchange phase, the switch couples its processor node or an uplink data source to a downlink destination (which may include a processor node or a robot), or couples an uplink source to its processor node and its processor node to a downlink destination. 9 figs.

  11. E-Print Network 3.0 - asynchronous parallel iterative Sample...

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

    computations for image analysis... .Y., Parallel asynchronous watershed algorithm-architecture. IEEE Transactions on Parallel and Distributed... ., An asynchronous cellular...

  12. THE MASSIVE SATELLITE POPULATION OF MILKY-WAY-SIZED GALAXIES

    SciTech Connect (OSTI)

    Rodriguez-Puebla, Aldo; Avila-Reese, Vladimir; Drory, Niv, E-mail: apuebla@astro.unam.mx [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, A. P. 70-264, 04510 Mexico, DF (Mexico)

    2013-08-20T23:59:59.000Z

    Several occupational distributions for satellite galaxies more massive than m{sub *} Almost-Equal-To 4 Multiplication-Sign 10{sup 7} M{sub Sun} around Milky-Way (MW)-sized hosts are presented and used to predict the internal dynamics of these satellites as a function of m{sub *}. For the analysis, a large galaxy group mock catalog is constructed on the basis of (sub)halo-to-stellar mass relations fully constrained with currently available observations, namely the galaxy stellar mass function decomposed into centrals and satellites, and the two-point correlation functions at different masses. We find that 6.6% of MW-sized galaxies host two satellites in the mass range of the Small and Large Magellanic Clouds (SMC and LMC, respectively). The probabilities of the MW-sized galaxies having one satellite equal to or larger than the LMC, two satellites equal to or larger than the SMC, or three satellites equal to or larger than Sagittarius (Sgr) are Almost-Equal-To 0.26, 0.14, and 0.14, respectively. The cumulative satellite mass function of the MW, N{sub s} ({>=}m{sub *}) , down to the mass of the Fornax dwarf is within the 1{sigma} distribution of all the MW-sized galaxies. We find that MW-sized hosts with three satellites more massive than Sgr (as the MW) are among the most common cases. However, the most and second most massive satellites in these systems are smaller than the LMC and SMC by roughly 0.7 and 0.8 dex, respectively. We conclude that the distribution N{sub s} ({>=}m{sub *}) for MW-sized galaxies is quite broad, the particular case of the MW being of low frequency but not an outlier. The halo mass of MW-sized galaxies correlates only weakly with N{sub s} ({>=}m{sub *}). Then, it is not possible to accurately determine the MW halo mass by means of its N{sub s} ({>=}m{sub *}); from our catalog, we constrain a lower limit of 1.38 Multiplication-Sign 10{sup 12} M{sub Sun} at the 1{sigma} level. Our analysis strongly suggests that the abundance of massive subhalos should agree with the abundance of massive satellites in all MW-sized hosts, i.e., there is not a missing (massive) satellite problem for the {Lambda}CDM cosmology. However, we confirm that the maximum circular velocity, v{sub max}, of the subhalos of satellites smaller than m{sub *} {approx} 10{sup 8} M{sub Sun} is systematically larger than the v{sub max} inferred from current observational studies of the MW bright dwarf satellites; different from previous works, this conclusion is based on an analysis of the overall population of MW-sized galaxies. Some pieces of evidence suggest that the issue could refer only to satellite dwarfs but not to central dwarfs, then environmental processes associated with dwarfs inside host halos combined with supernova-driven core expansion should be on the basis of the lowering of v{sub max}.

  13. Sub-Second Parallel State Estimation

    SciTech Connect (OSTI)

    Chen, Yousu; Rice, Mark J.; Glaesemann, Kurt R.; Wang, Shaobu; Huang, Zhenyu

    2014-10-31T23:59:59.000Z

    This report describes the performance of Pacific Northwest National Laboratory (PNNL) sub-second parallel state estimation (PSE) tool using the utility data from the Bonneville Power Administrative (BPA) and discusses the benefits of the fast computational speed for power system applications. The test data were provided by BPA. They are two-days’ worth of hourly snapshots that include power system data and measurement sets in a commercial tool format. These data are extracted out from the commercial tool box and fed into the PSE tool. With the help of advanced solvers, the PSE tool is able to solve each BPA hourly state estimation problem within one second, which is more than 10 times faster than today’s commercial tool. This improved computational performance can help increase the reliability value of state estimation in many aspects: (1) the shorter the time required for execution of state estimation, the more time remains for operators to take appropriate actions, and/or to apply automatic or manual corrective control actions. This increases the chances of arresting or mitigating the impact of cascading failures; (2) the SE can be executed multiple times within time allowance. Therefore, the robustness of SE can be enhanced by repeating the execution of the SE with adaptive adjustments, including removing bad data and/or adjusting different initial conditions to compute a better estimate within the same time as a traditional state estimator’s single estimate. There are other benefits with the sub-second SE, such as that the PSE results can potentially be used in local and/or wide-area automatic corrective control actions that are currently dependent on raw measurements to minimize the impact of bad measurements, and provides opportunities to enhance the power grid reliability and efficiency. PSE also can enable other advanced tools that rely on SE outputs and could be used to further improve operators’ actions and automated controls to mitigate effects of severe events on the grid. The power grid continues to grow and the number of measurements is increasing at an accelerated rate due to the variety of smart grid devices being introduced. A parallel state estimation implementation will have better performance than traditional, sequential state estimation by utilizing the power of high performance computing (HPC). This increased performance positions parallel state estimators as valuable tools for operating the increasingly more complex power grid.

  14. Effective Fluid FLRW Cosmologies of Minimal Massive Gravity

    E-Print Network [OSTI]

    Nejat Tevfik Yilmaz

    2014-09-23T23:59:59.000Z

    By using a solution ansatz we partially decouple the metric and the Stuckelberg sectors of the minimal massive gravity (MMGR). In this scheme for a diagonal physical metric we find the general solutions for the scalars of the theory and the particular fiducial (background) metric which leads to these solutions. Then we adopt this general formalism to construct the derivation of new FLRW cosmologies of the theory in the presence of a so-called effective ideal fluid which arises from our solution ansatz as a modifying, non-physical source for the Einstein and the corresponding Friedmann equations.

  15. Translation invariant time-dependent massive gravity: Hamiltonian analysis

    E-Print Network [OSTI]

    Jihad Mourad; Karim Noui; Danièle A. Steer

    2014-07-10T23:59:59.000Z

    The canonical structure of the massive gravity in the first order moving frame formalism is studied. We work in the simplified context of translation invariant fields, with mass terms given by general non-derivative interactions, invariant under the diagonal Lorentz group, depending on the moving frame as well as a fixed reference frame. We prove that the only mass terms which give 5 propagating degrees of freedom are the dRGT mass terms, namely those which are linear in the lapse. We also complete the Hamiltonian analysis with the dynamical evolution of the system.

  16. Stability of the self-accelerating universe in massive gravity

    SciTech Connect (OSTI)

    Khosravi, Nima [Cosmology Group, African Institute for Mathematical Sciences, Muizenberg, 7945 (South Africa); Niz, Gustavo; Koyama, Kazuya; Tasinato, Gianmassimo, E-mail: nima@aims.ac.za, E-mail: g.niz@ugto.mx, E-mail: Kazuya.Koyama@port.ac.uk, E-mail: gianmassimo.tasinato@port.ac.uk [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom)

    2013-08-01T23:59:59.000Z

    We study linear perturbations around time dependent spherically symmetric solutions in the ?{sub 3} massive gravity theory, which self-accelerate in the vacuum. We find that the dynamics of the scalar perturbations depend on the choice of the fiducial metric for the background solutions. For particular choice of fiducial metric there is a symmetry enhancement, leaving no propagating scalar degrees of freedom at linear order in perturbations. In contrast, any other choice propagates a single scalar mode. We find that the Hamiltonian of this scalar mode is unbounded from below for all self-accelerating solutions, signalling an instability.

  17. Anisotropic massive strings in scalar-tensor theory of gravitation

    E-Print Network [OSTI]

    Anil Kumar Yadav

    2012-11-15T23:59:59.000Z

    We present the model of anisotropic universe with string fluid as source of matter within the framework of scalar-tensor theory of gravitation. Exact solution of field equations are obtained by applying Berman's law of variation of Hubble's parameter which yields a constant value of DP. The nature of classical potential is examined for the model under consideration. It has been also found that the massive strings dominate in early universe and at long last disappear from universe. This is in agreement with current astronomical observations. The physical and dynamical properties of model are also discussed.

  18. Solar-like oscillations in a massive star

    E-Print Network [OSTI]

    Belkacem, K; Goupil, M -J; Lefèvre, L; Baudin, F; Deheuvels, S; Dupret, M -A; Appourchaux, T; Scuflaire, R; Auvergne, M; Catala, C; Michel, E; Miglio, A; Montalban, J; Thoul, A; Talon, S; Baglin, A; Noels, A

    2009-01-01T23:59:59.000Z

    Seismology of stars provides insight into the physical mechanisms taking place in their interior, with modes of oscillation probing different layers. Low-amplitude acoustic oscillations excited by turbulent convection were detected four decades ago in the Sun and more recently in low-mass main-sequence stars. Using data gathered by the Convection Rotation and Planetary Transits mission, we report here on the detection of solar-like oscillations in a massive star, V1449 Aql, which is a known large-amplitude (b Cephei) pulsator.

  19. Massive zero-metal stars: Energy production and mixing

    E-Print Network [OSTI]

    C. W. Straka; W. M. Tscharnuter

    2001-03-21T23:59:59.000Z

    Time-dependent nuclear network calculations at constant temperature show that for zero-metal stars >= 20 Msun (i) beta-decay reactions and (ii) the 13N(p,gamma)14O reaction must be included. It is also shown that the nuclear timescale in these zero-metal stars is shorter than the mixing timescale and therefore the assumption of instantaneous mixing across convective regions is not fulfilled. We conclude that proper modeling of these processes may alter the evolution of massive zero-metal stars.

  20. On the new massive gravity and AdS/CFT

    E-Print Network [OSTI]

    Aninda Sinha

    2010-08-11T23:59:59.000Z

    Demanding the existence of a simple holographic $c$-theorem, it is shown that a general (parity preserving) theory of gravity in 2+1 dimensions involving upto four derivative curvature invariants reduces to the new massive gravity theory. We consider extending the theory including upto six derivative curvature invariants. Black hole solutions are presented and consistency with 1+1 CFTs is checked. We present evidence that bulk unitarity is still in conflict with a positive CFT central charge for generic choice of parameters. However, for a special choice of parameters appearing in the four and six derivative terms reduces the linearized equations to be two derivative, thereby ameliorating the unitarity problem.

  1. Neutrino Tomography of Gamma Ray Bursts and Massive Stellar Collapses

    E-Print Network [OSTI]

    Soebur Razzaque; Peter Meszaros; Eli Waxman

    2003-10-14T23:59:59.000Z

    Neutrinos at energies above TeV can serve as probes of the stellar progenitor and jet dynamics of gamma ray bursts arising from stellar core collapses. They can also probe collapses which do not lead to gamma-rays, which may be much more numerous. We calculate detailed neutrino spectra from shock accelerated protons in jets just below the outer stellar envelope, before their emergence. We present neutrino flux estimates from such pre-burst jets for two different massive stellar progenitor models. These should be distinguishable by IceCube, and we discuss the implications.

  2. Ball State building massive geothermal system | Department of Energy

    Energy Savers [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 Delicious RankCombustionImprovement3--Logistical5/08 Attendance List1-02EvaluationJohnBall State building massive

  3. Application of a parallel DSMC method to hypersonic rarefied flows

    SciTech Connect (OSTI)

    Wilmoth, R.G. (NASA, Langley Research Center, Hampton, VA (USA))

    1991-01-01T23:59:59.000Z

    This paper describes a method for doing direct simulation Monte Carlo (DSMC) calculations using parallel processing and presents some results of applying the method to several hypersonic, rarefied flow problems. The performance and efficiency of the parallel method are discussed. The applications described are the flow in a channel and the flow about a flat plate at incidence. The results show significant advantages of parallel processing over conventional scalar processing and demonstrate the scalability of the method to large problems. 8 refs.

  4. MC++: Parallel, portable, Monte Carlo neutron transport in C++

    SciTech Connect (OSTI)

    Lee, S.R.; Cummings, J.C. [Los Alamos National Lab., NM (United States); Nolen, S.D. [Texas A& M Univ., College Station, TX (United States). Dept. of Nuclear Engineering

    1997-02-01T23:59:59.000Z

    We have developed an implicit Monte Carlo neutron transport code in C++ using the Parallel Object-Oriented Methods and Applications (POOMA) class library. MC++ runs in parallel on and is portable to a wide variety of platforms, including MPPs, clustered SMPs, and individual workstations. It contains appropriate classes and abstractions for particle transport and parallelism. Current capabilities of MC++ are discussed, along with future plans and physics and performance results on many different platforms.

  5. Link failure detection in a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J. (Rochester, MN); Blocksome, Michael A. (Rochester, MN); Megerian, Mark G. (Rochester, MN); Smith, Brian E. (Rochester, MN)

    2010-11-09T23:59:59.000Z

    Methods, apparatus, and products are disclosed for link failure detection in a parallel computer including compute nodes connected in a rectangular mesh network, each pair of adjacent compute nodes in the rectangular mesh network connected together using a pair of links, that includes: assigning each compute node to either a first group or a second group such that adjacent compute nodes in the rectangular mesh network are assigned to different groups; sending, by each of the compute nodes assigned to the first group, a first test message to each adjacent compute node assigned to the second group; determining, by each of the compute nodes assigned to the second group, whether the first test message was received from each adjacent compute node assigned to the first group; and notifying a user, by each of the compute nodes assigned to the second group, whether the first test message was received.

  6. Broadcasting a message in a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J; Faraj, Daniel A

    2014-11-18T23:59:59.000Z

    Methods, systems, and products are disclosed for broadcasting a message in a parallel computer that includes: transmitting, by the logical root to all of the nodes directly connected to the logical root, a message; and for each node except the logical root: receiving the message; if that node is the physical root, then transmitting the message to all of the child nodes except the child node from which the message was received; if that node received the message from a parent node and if that node is not a leaf node, then transmitting the message to all of the child nodes; and if that node received the message from a child node and if that node is not the physical root, then transmitting the message to all of the child nodes except the child node from which the message was received and transmitting the message to the parent node.

  7. Parallel detecting, spectroscopic ellipsometers/polarimeters

    DOE Patents [OSTI]

    Furtak, Thomas E. (15927 W. Ellsworth, Golden, CO 80401)

    2002-01-01T23:59:59.000Z

    The parallel detecting spectroscopic ellipsometer/polarimeter sensor has no moving parts and operates in real-time for in-situ monitoring of the thin film surface properties of a sample within a processing chamber. It includes a multi-spectral source of radiation for producing a collimated beam of radiation directed towards the surface of the sample through a polarizer. The thus polarized collimated beam of radiation impacts and is reflected from the surface of the sample, thereby changing its polarization state due to the intrinsic material properties of the sample. The light reflected from the sample is separated into four separate polarized filtered beams, each having individual spectral intensities. Data about said four individual spectral intensities is collected within the processing chamber, and is transmitted into one or more spectrometers. The data of all four individual spectral intensities is then analyzed using transformation algorithms, in real-time.

  8. Clock Agreement Among Parallel Supercomputer Nodes

    SciTech Connect (OSTI)

    Jones, Terry R.; Koenig, Gregory A.

    2014-04-30T23:59:59.000Z

    This dataset presents measurements that quantify the clock synchronization time-agreement characteristics among several high performance computers including the current world's most powerful machine for open science, the U.S. Department of Energy's Titan machine sited at Oak Ridge National Laboratory. These ultra-fast machines derive much of their computational capability from extreme node counts (over 18000 nodes in the case of the Titan machine). Time-agreement is commonly utilized by parallel programming applications and tools, distributed programming application and tools, and system software. Our time-agreement measurements detail the degree of time variance between nodes and how that variance changes over time. The dataset includes empirical measurements and the accompanying spreadsheets.

  9. Clock Agreement Among Parallel Supercomputer Nodes

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

    Jones, Terry R.; Koenig, Gregory A.

    This dataset presents measurements that quantify the clock synchronization time-agreement characteristics among several high performance computers including the current world's most powerful machine for open science, the U.S. Department of Energy's Titan machine sited at Oak Ridge National Laboratory. These ultra-fast machines derive much of their computational capability from extreme node counts (over 18000 nodes in the case of the Titan machine). Time-agreement is commonly utilized by parallel programming applications and tools, distributed programming application and tools, and system software. Our time-agreement measurements detail the degree of time variance between nodes and how that variance changes over time. The dataset includes empirical measurements and the accompanying spreadsheets.

  10. The WFPC2 Archival Parallels Project

    E-Print Network [OSTI]

    Yogesh Wadadekar; Stefano Casertano; Richard Hook; Bül ent K?z?ltan; Anton Koekemoer; Harry Ferguson; Doichin Denchev

    2005-11-08T23:59:59.000Z

    We describe the methods and procedures developed to obtain a near-automatic combination of WFPC2 images obtained as part of the WFPC2 Archival Pure Parallels program. Several techniques have been developed or refined to ensure proper alignment, registration, and combination of overlapping images that can be obtained at different times and with different orientations. We quantify the success rate and the accuracy of the registration of images of different types, and we develop techniques suitable to equalize the sky background without unduly affecting extended emission. About 600 combined images of the 1,500 eventually planned have already been publicly released through the STScI Archive. The images released to date are especially suited to study star formation in the Magellanic Clouds, the stellar population in the halo of nearby galaxies, and the properties of star-forming galaxies at $ z \\sim 3 $.

  11. Optimized data communications in a parallel computer

    DOE Patents [OSTI]

    Faraj, Daniel A.

    2014-08-19T23:59:59.000Z

    A parallel computer includes nodes that include a network adapter that couples the node in a point-to-point network and supports communications in opposite directions of each dimension. Optimized communications include: receiving, by a network adapter of a receiving compute node, a packet--from a source direction--that specifies a destination node and deposit hints. Each hint is associated with a direction within which the packet is to be deposited. If a hint indicates the packet to be deposited in the opposite direction: the adapter delivers the packet to an application on the receiving node; forwards the packet to a next node in the opposite direction if the receiving node is not the destination; and forwards the packet to a node in a direction of a subsequent dimension if the hints indicate that the packet is to be deposited in the direction of the subsequent dimension.

  12. Broadcasting a message in a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J; Faraj, Ahmad A

    2013-04-16T23:59:59.000Z

    Methods, systems, and products are disclosed for broadcasting a message in a parallel computer that includes: transmitting, by the logical root to all of the nodes directly connected to the logical root, a message; and for each node except the logical root: receiving the message; if that node is the physical root, then transmitting the message to all of the child nodes except the child node from which the message was received; if that node received the message from a parent node and if that node is not a leaf node, then transmitting the message to all of the child nodes; and if that node received the message from a child node and if that node is not the physical root, then transmitting the message to all of the child nodes except the child node from which the message was received and transmitting the message to the parent node.

  13. Optimized data communications in a parallel computer

    DOE Patents [OSTI]

    Faraj, Daniel A

    2014-10-21T23:59:59.000Z

    A parallel computer includes nodes that include a network adapter that couples the node in a point-to-point network and supports communications in opposite directions of each dimension. Optimized communications include: receiving, by a network adapter of a receiving compute node, a packet--from a source direction--that specifies a destination node and deposit hints. Each hint is associated with a direction within which the packet is to be deposited. If a hint indicates the packet to be deposited in the opposite direction: the adapter delivers the packet to an application on the receiving node; forwards the packet to a next node in the opposite direction if the receiving node is not the destination; and forwards the packet to a node in a direction of a subsequent dimension if the hints indicate that the packet is to be deposited in the direction of the subsequent dimension.

  14. Internode data communications in a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J.; Blocksome, Michael A.; Miller, Douglas R.; Parker, Jeffrey J.; Ratterman, Joseph D.; Smith, Brian E.

    2013-09-03T23:59:59.000Z

    Internode data communications in a parallel computer that includes compute nodes that each include main memory and a messaging unit, the messaging unit including computer memory and coupling compute nodes for data communications, in which, for each compute node at compute node boot time: a messaging unit allocates, in the messaging unit's computer memory, a predefined number of message buffers, each message buffer associated with a process to be initialized on the compute node; receives, prior to initialization of a particular process on the compute node, a data communications message intended for the particular process; and stores the data communications message in the message buffer associated with the particular process. Upon initialization of the particular process, the process establishes a messaging buffer in main memory of the compute node and copies the data communications message from the message buffer of the messaging unit into the message buffer of main memory.

  15. Intranode data communications in a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J; Blocksome, Michael A; Miller, Douglas R; Ratterman, Joseph D; Smith, Brian E

    2014-01-07T23:59:59.000Z

    Intranode data communications in a parallel computer that includes compute nodes configured to execute processes, where the data communications include: allocating, upon initialization of a first process of a computer node, a region of shared memory; establishing, by the first process, a predefined number of message buffers, each message buffer associated with a process to be initialized on the compute node; sending, to a second process on the same compute node, a data communications message without determining whether the second process has been initialized, including storing the data communications message in the message buffer of the second process; and upon initialization of the second process: retrieving, by the second process, a pointer to the second process's message buffer; and retrieving, by the second process from the second process's message buffer in dependence upon the pointer, the data communications message sent by the first process.

  16. Intranode data communications in a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J; Blocksome, Michael A; Miller, Douglas R; Ratterman, Joseph D; Smith, Brian E

    2013-07-23T23:59:59.000Z

    Intranode data communications in a parallel computer that includes compute nodes configured to execute processes, where the data communications include: allocating, upon initialization of a first process of a compute node, a region of shared memory; establishing, by the first process, a predefined number of message buffers, each message buffer associated with a process to be initialized on the compute node; sending, to a second process on the same compute node, a data communications message without determining whether the second process has been initialized, including storing the data communications message in the message buffer of the second process; and upon initialization of the second process: retrieving, by the second process, a pointer to the second process's message buffer; and retrieving, by the second process from the second process's message buffer in dependence upon the pointer, the data communications message sent by the first process.

  17. Internode data communications in a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J; Blocksome, Michael A; Miller, Douglas R; Parker, Jeffrey J; Ratterman, Joseph D; Smith, Brian E

    2014-02-11T23:59:59.000Z

    Internode data communications in a parallel computer that includes compute nodes that each include main memory and a messaging unit, the messaging unit including computer memory and coupling compute nodes for data communications, in which, for each compute node at compute node boot time: a messaging unit allocates, in the messaging unit's computer memory, a predefined number of message buffers, each message buffer associated with a process to be initialized on the compute node; receives, prior to initialization of a particular process on the compute node, a data communications message intended for the particular process; and stores the data communications message in the message buffer associated with the particular process. Upon initialization of the particular process, the process establishes a messaging buffer in main memory of the compute node and copies the data communications message from the message buffer of the messaging unit into the message buffer of main memory.

  18. Parallel multiscale simulations of a brain aneurysm

    SciTech Connect (OSTI)

    Grinberg, Leopold [Division of Applied Mathematics, Brown University, Providence, RI 02912 (United States)] [Division of Applied Mathematics, Brown University, Providence, RI 02912 (United States); Fedosov, Dmitry A. [Institute of Complex Systems and Institute for Advanced Simulation, Forschungszentrum Jülich, Jülich 52425 (Germany)] [Institute of Complex Systems and Institute for Advanced Simulation, Forschungszentrum Jülich, Jülich 52425 (Germany); Karniadakis, George Em, E-mail: george_karniadakis@brown.edu [Division of Applied Mathematics, Brown University, Providence, RI 02912 (United States)

    2013-07-01T23:59:59.000Z

    Cardiovascular pathologies, such as a brain aneurysm, are affected by the global blood circulation as well as by the local microrheology. Hence, developing computational models for such cases requires the coupling of disparate spatial and temporal scales often governed by diverse mathematical descriptions, e.g., by partial differential equations (continuum) and ordinary differential equations for discrete particles (atomistic). However, interfacing atomistic-based with continuum-based domain discretizations is a challenging problem that requires both mathematical and computational advances. We present here a hybrid methodology that enabled us to perform the first multiscale simulations of platelet depositions on the wall of a brain aneurysm. The large scale flow features in the intracranial network are accurately resolved by using the high-order spectral element Navier–Stokes solver N??T?r. The blood rheology inside the aneurysm is modeled using a coarse-grained stochastic molecular dynamics approach (the dissipative particle dynamics method) implemented in the parallel code LAMMPS. The continuum and atomistic domains overlap with interface conditions provided by effective forces computed adaptively to ensure continuity of states across the interface boundary. A two-way interaction is allowed with the time-evolving boundary of the (deposited) platelet clusters tracked by an immersed boundary method. The corresponding heterogeneous solvers (N??T?r and LAMMPS) are linked together by a computational multilevel message passing interface that facilitates modularity and high parallel efficiency. Results of multiscale simulations of clot formation inside the aneurysm in a patient-specific arterial tree are presented. We also discuss the computational challenges involved and present scalability results of our coupled solver on up to 300 K computer processors. Validation of such coupled atomistic-continuum models is a main open issue that has to be addressed in future work.

  19. Improving Between-Shot Fusion Data Analysis with Parallel Structures

    SciTech Connect (OSTI)

    CHET NIETER

    2005-07-27T23:59:59.000Z

    In the Phase I project we concentrated on three technical objectives to demonstrate the feasibility of the Phase II project: (1) the development of a parallel MDSplus data handler, (2) the parallelization of existing fusion data analysis packages, and (3) the development of techniques to automatically generate parallelized code using pre-compiler directives. We summarize the results of the Phase I research for each of these objectives below. We also describe below additional accomplishments related to the development of the TaskDL and mpiDL parallelization packages.

  20. An Exact Extended Formulation for the Unrelated Parallel Machine ...

    E-Print Network [OSTI]

    Kerem Bulbul

    2014-08-28T23:59:59.000Z

    Aug 28, 2014 ... Abstract: The plethora of research on NP-hard parallel machine scheduling problems is focused on heuristics due to the theoretically and ...

  1. Parallel machine match-up scheduling with manufacturing cost considerations

    E-Print Network [OSTI]

    Aktürk, M. Selim; Atamtürk, Alper; Gürel, Sinan

    2010-01-01T23:59:59.000Z

    approach for the single machine scheduling problem. Journaldecisions on parallel CNC machines: -constraint approach.mechanism for the CNC machine scheduling problems with

  2. A parallel between two classes of pricing problems in transportation ...

    E-Print Network [OSTI]

    G raldine Heilporn

    2009-01-05T23:59:59.000Z

    Jan 5, 2009 ... A parallel between two classes of pricing problems in transportation and economics. G raldine Heilporn (Geraldine.Heilporn ***at*** hec.ca)

  3. advanced parallel processing: Topics by E-print Network

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

    Meets Markov Jaillet, Patrick 83 January 9, 2014 10:13 WSPCINSTRUCTION FILE ppl-benoit Parallel Processing Letters Physics Websites Summary: January 9, 2014 10:13...

  4. Hybrid MPI/OpenMP parallel support vector machine training

    E-Print Network [OSTI]

    Kristian Woodsend

    2009-01-12T23:59:59.000Z

    Jan 12, 2009 ... A parallel implementation of Support Vector Machine training has been developed, using a combination of MPI and OpenMP. Using an interior ...

  5. A Parallel Line Search Subspace Correction Method for Composite ...

    E-Print Network [OSTI]

    Qian Dong

    2014-10-07T23:59:59.000Z

    Oct 7, 2014 ... Abstract: In this paper, we investigate a parallel subspace correction framework for composite convex optimization. The variables are first ...

  6. Parallel Large-Neighborhood Search Techniques for LNG Inventory ...

    E-Print Network [OSTI]

    Badrinarayanan Velamur Asokan

    2014-04-17T23:59:59.000Z

    Apr 17, 2014 ... Parallel Large-Neighborhood Search Techniques for LNG Inventory Routing. Badrinarayanan Velamur Asokan(badri.velamur.asokan ***at*** ...

  7. Hybrid Parallelism for Volume Rendering at Large Scale at NERSC

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

    Volume Rendering at Large Scale Hybrid Parallelism for Volume Rendering at Large Scale volrend-swes.png We studied the performance and scalability characteristics of hybrid''...

  8. Exponential neighborhood search for a parallel machine scheduling ...

    E-Print Network [OSTI]

    2006-08-09T23:59:59.000Z

    Sun and Wang [26] consider the identical parallel machine problem with a large ...... be found in the OR-Library which is a collection of instances for operations ...

  9. Massive disk outflows mediated by extreme magnetic fields

    E-Print Network [OSTI]

    Shiber, Sagiv; Soker, Noam

    2015-01-01T23:59:59.000Z

    We argue that magnetic fields amplified within a very high accretion-rate disk around main sequence stars can lead to the formation of massive bipolar outflows that can remove most of the disk's mass and energy. This efficient directional removal of energy and mass allows the high accretion-rate disk to be built. We construct thick disks where the magnetic fields are amplified by an Alpha-Omega dynamo in the disk, bringing the fluctuating components of the magnetic field to be much stronger than the large-scale component. By examining the possible activity of the magnetic fields we conclude that main sequence stars can accrete mass at very high rates, up to 0.01Mo/yr for solar type stars, and up to 1Mo/yr for very massive stars. Such energetic outflows can account for the powering of some eruptive objects, such as merging main sequence stars, major eruptions of luminous blue variables, such as the Great Eruption of Eta Carinae, and other intermediate luminosity optical transients (ILOTs; Red Novae; Red Transi...

  10. PROTOSTELLAR OUTFLOW HEATING IN A GROWING MASSIVE PROTOCLUSTER

    SciTech Connect (OSTI)

    Wang Ke; Wu Yuefang; Zhang Huawei [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China); Zhang Qizhou [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Li Huabai, E-mail: kwang@cfa.harvard.edu [Max-Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany)

    2012-02-15T23:59:59.000Z

    The dense molecular clump P1 in the infrared dark cloud complex G28.34+0.06 harbors a massive protostellar cluster at its extreme youth. Our previous Submillimeter Array observations revealed several jet-like CO outflows emanating from the protostars, indicative of intense accretion and potential interaction with ambient natal materials. Here, we present the Expanded Very Large Array spectral line observations toward P1 in the NH{sub 3} (J,K) = (1,1), (2,2), (3,3) lines, as well as H{sub 2}O and class I CH{sub 3}OH masers. Multiple NH{sub 3} transitions reveal the heated gas widely spread in the 1 pc clump. The temperature distribution is highly structured; the heated gas is offset from the protostars, and morphologically matches the outflows very well. Hot spots of spatially compact, spectrally broad NH{sub 3} (3,3) emission features are also found coincident with the outflows. A weak NH{sub 3} (3,3) maser is discovered at the interface between an outflow jet and the ambient gas. These findings suggest that protostellar heating may not be effective in suppressing fragmentation during the formation of massive cores.

  11. Data communications for a collective operation in a parallel active messaging interface of a parallel computer

    DOE Patents [OSTI]

    Faraj, Daniel A

    2013-07-16T23:59:59.000Z

    Algorithm selection for data communications in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI composed of data communications endpoints, each endpoint including specifications of a client, a context, and a task, endpoints coupled for data communications through the PAMI, including associating in the PAMI data communications algorithms and bit masks; receiving in an origin endpoint of the PAMI a collective instruction, the instruction specifying transmission of a data communications message from the origin endpoint to a target endpoint; constructing a bit mask for the received collective instruction; selecting, from among the associated algorithms and bit masks, a data communications algorithm in dependence upon the constructed bit mask; and executing the collective instruction, transmitting, according to the selected data communications algorithm from the origin endpoint to the target endpoint, the data communications message.

  12. Data communications in a parallel active messaging interface of a parallel computer

    DOE Patents [OSTI]

    Davis, Kristan D; Faraj, Daniel A

    2013-07-09T23:59:59.000Z

    Algorithm selection for data communications in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI composed of data communications endpoints, each endpoint including specifications of a client, a context, and a task, endpoints coupled for data communications through the PAMI, including associating in the PAMI data communications algorithms and ranges of message sizes so that each algorithm is associated with a separate range of message sizes; receiving in an origin endpoint of the PAMI a data communications instruction, the instruction specifying transmission of a data communications message from the origin endpoint to a target endpoint, the data communications message characterized by a message size; selecting, from among the associated algorithms and ranges, a data communications algorithm in dependence upon the message size; and transmitting, according to the selected data communications algorithm from the origin endpoint to the target endpoint, the data communications message.

  13. Fencing direct memory access data transfers in a parallel active messaging interface of a parallel computer

    DOE Patents [OSTI]

    Blocksome, Michael A; Mamidala, Amith R

    2014-02-11T23:59:59.000Z

    Fencing direct memory access (`DMA`) data transfers in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI including data communications endpoints, each endpoint including specifications of a client, a context, and a task, the endpoints coupled for data communications through the PAMI and through DMA controllers operatively coupled to segments of shared random access memory through which the DMA controllers deliver data communications deterministically, including initiating execution through the PAMI of an ordered sequence of active DMA instructions for DMA data transfers between two endpoints, effecting deterministic DMA data transfers through a DMA controller and a segment of shared memory; and executing through the PAMI, with no FENCE accounting for DMA data transfers, an active FENCE instruction, the FENCE instruction completing execution only after completion of all DMA instructions initiated prior to execution of the FENCE instruction for DMA data transfers between the two endpoints.

  14. Data communications in a parallel active messaging interface of a parallel computer

    DOE Patents [OSTI]

    Davis, Kristan D.; Faraj, Daniel A.

    2014-07-22T23:59:59.000Z

    Algorithm selection for data communications in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI composed of data communications endpoints, each endpoint including specifications of a client, a context, and a task, endpoints coupled for data communications through the PAMI, including associating in the PAMI data communications algorithms and ranges of message sizes so that each algorithm is associated with a separate range of message sizes; receiving in an origin endpoint of the PAMI a data communications instruction, the instruction specifying transmission of a data communications message from the origin endpoint to a target endpoint, the data communications message characterized by a message size; selecting, from among the associated algorithms and ranges, a data communications algorithm in dependence upon the message size; and transmitting, according to the selected data communications algorithm from the origin endpoint to the target endpoint, the data communications message.

  15. Fencing direct memory access data transfers in a parallel active messaging interface of a parallel computer

    DOE Patents [OSTI]

    Blocksome, Michael A.; Mamidala, Amith R.

    2013-09-03T23:59:59.000Z

    Fencing direct memory access (`DMA`) data transfers in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI including data communications endpoints, each endpoint including specifications of a client, a context, and a task, the endpoints coupled for data communications through the PAMI and through DMA controllers operatively coupled to segments of shared random access memory through which the DMA controllers deliver data communications deterministically, including initiating execution through the PAMI of an ordered sequence of active DMA instructions for DMA data transfers between two endpoints, effecting deterministic DMA data transfers through a DMA controller and a segment of shared memory; and executing through the PAMI, with no FENCE accounting for DMA data transfers, an active FENCE instruction, the FENCE instruction completing execution only after completion of all DMA instructions initiated prior to execution of the FENCE instruction for DMA data transfers between the two endpoints.

  16. Data communications in a parallel active messaging interface of a parallel computer

    DOE Patents [OSTI]

    Blocksome, Michael A.; Ratterman, Joseph D.; Smith, Brian E.

    2014-09-16T23:59:59.000Z

    Eager send data communications in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI composed of data communications endpoints that specify a client, a context, and a task, including receiving an eager send data communications instruction with transfer data disposed in a send buffer characterized by a read/write send buffer memory address in a read/write virtual address space of the origin endpoint; determining for the send buffer a read-only send buffer memory address in a read-only virtual address space, the read-only virtual address space shared by both the origin endpoint and the target endpoint, with all frames of physical memory mapped to pages of virtual memory in the read-only virtual address space; and communicating by the origin endpoint to the target endpoint an eager send message header that includes the read-only send buffer memory address.

  17. Data communications in a parallel active messaging interface of a parallel computer

    DOE Patents [OSTI]

    Blocksome, Michael A.; Ratterman, Joseph D.; Smith, Brian E.

    2014-09-02T23:59:59.000Z

    Eager send data communications in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI composed of data communications endpoints that specify a client, a context, and a task, including receiving an eager send data communications instruction with transfer data disposed in a send buffer characterized by a read/write send buffer memory address in a read/write virtual address space of the origin endpoint; determining for the send buffer a read-only send buffer memory address in a read-only virtual address space, the read-only virtual address space shared by both the origin endpoint and the target endpoint, with all frames of physical memory mapped to pages of virtual memory in the read-only virtual address space; and communicating by the origin endpoint to the target endpoint an eager send message header that includes the read-only send buffer memory address.

  18. Data communications in a parallel active messaging interface of a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J; Blocksome, Michael A; Ratterman, Joseph D; Smith, Brian E

    2014-11-18T23:59:59.000Z

    Data communications in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI composed of data communications endpoints, each endpoint including a specification of data communications parameters for a thread of execution on a compute node, including specifications of a client, a context, and a task, endpoints coupled for data communications through the PAMI and through data communications resources, including receiving in an origin endpoint of the PAMI a SEND instruction, the SEND instruction specifying a transmission of transfer data from the origin endpoint to a first target endpoint; transmitting from the origin endpoint to the first target endpoint a Request-To-Send (`RTS`) message advising the first target endpoint of the location and size of the transfer data; assigning by the first target endpoint to each of a plurality of target endpoints separate portions of the transfer data; and receiving by the plurality of target endpoints the transfer data.

  19. Programming for Locality and Parallelism with Hierarchically Tiled ArraysJuly 13, 2003 1 Programming for Locality and Parallelism with

    E-Print Network [OSTI]

    Padua, David

    - guages, Co-Array Fortran [NuRe98] and Unified Parallel C (UPC) [CDCY99]. Our pro- posal follows these two

  20. Current parallel I/O limitations to scalable data analysis.

    SciTech Connect (OSTI)

    Mascarenhas, Ajith Arthur; Pebay, Philippe Pierre

    2011-07-01T23:59:59.000Z

    This report describes the limitations to parallel scalability which we have encountered when applying our otherwise optimally scalable parallel statistical analysis tool kit to large data sets distributed across the parallel file system of the current premier DOE computational facility. This report describes our study to evaluate the effect of parallel I/O on the overall scalability of a parallel data analysis pipeline using our scalable parallel statistics tool kit [PTBM11]. In this goal, we tested it using the Jaguar-pf DOE/ORNL peta-scale platform on a large combustion simulation data under a variety of process counts and domain decompositions scenarios. In this report we have recalled the foundations of the parallel statistical analysis tool kit which we have designed and implemented, with the specific double intent of reproducing typical data analysis workflows, and achieving optimal design for scalable parallel implementations. We have briefly reviewed those earlier results and publications which allow us to conclude that we have achieved both goals. However, in this report we have further established that, when used in conjuction with a state-of-the-art parallel I/O system, as can be found on the premier DOE peta-scale platform, the scaling properties of the overall analysis pipeline comprising parallel data access routines degrade rapidly. This finding is problematic and must be addressed if peta-scale data analysis is to be made scalable, or even possible. In order to attempt to address these parallel I/O limitations, we will investigate the use the Adaptable IO System (ADIOS) [LZL+10] to improve I/O performance, while maintaining flexibility for a variety of IO options, such MPI IO, POSIX IO. This system is developed at ORNL and other collaborating institutions, and is being tested extensively on Jaguar-pf. Simulation code being developed on these systems will also use ADIOS to output the data thereby making it easier for other systems, such as ours, to process that data.

  1. The effect of massive neutrinos on the SZ and X-ray observables of galaxy clusters

    E-Print Network [OSTI]

    Roncarelli, M; Moscardini, L

    2014-01-01T23:59:59.000Z

    Massive neutrinos are expected to influence the formation of the large-scale structure of the Universe, depending on the value of their total mass, $\\Sigma m_\

  2. Constraints on the Structure, Evolution, and Approach to Thermonuclear Runaway in Intermediate Mass and Massive Stars.

    E-Print Network [OSTI]

    Dolan, Michelle Marie

    2013-01-01T23:59:59.000Z

    ??This thesis provides an assessment of stellar evolution models for intermediate-mass and massive stars in advanced stages of evolution through a detailed cooperation between simulations… (more)

  3. Eighth SIAM conference on parallel processing for scientific computing: Final program and abstracts

    SciTech Connect (OSTI)

    NONE

    1997-12-31T23:59:59.000Z

    This SIAM conference is the premier forum for developments in parallel numerical algorithms, a field that has seen very lively and fruitful developments over the past decade, and whose health is still robust. Themes for this conference were: combinatorial optimization; data-parallel languages; large-scale parallel applications; message-passing; molecular modeling; parallel I/O; parallel libraries; parallel software tools; parallel compilers; particle simulations; problem-solving environments; and sparse matrix computations.

  4. Endpoint-based parallel data processing with non-blocking collective instructions in a parallel active messaging interface of a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J; Blocksome, Michael A; Cernohous, Bob R; Ratterman, Joseph D; Smith, Brian E

    2014-11-18T23:59:59.000Z

    Methods, apparatuses, and computer program products for endpoint-based parallel data processing with non-blocking collective instructions in a parallel active messaging interface (`PAMI`) of a parallel computer are provided. Embodiments include establishing by a parallel application a data communications geometry, the geometry specifying a set of endpoints that are used in collective operations of the PAMI, including associating with the geometry a list of collective algorithms valid for use with the endpoints of the geometry. Embodiments also include registering in each endpoint in the geometry a dispatch callback function for a collective operation and executing without blocking, through a single one of the endpoints in the geometry, an instruction for the collective operation.

  5. Particle Transport in Parallel-Plate Reactors

    SciTech Connect (OSTI)

    Rader, D.J.; Geller, A.S.

    1999-08-01T23:59:59.000Z

    A major cause of semiconductor yield degradation is contaminant particles that deposit on wafers while they reside in processing tools during integrated circuit manufacturing. This report presents numerical models for assessing particle transport and deposition in a parallel-plate geometry characteristic of a wide range of single-wafer processing tools: uniform downward flow exiting a perforated-plate showerhead separated by a gap from a circular wafer resting on a parallel susceptor. Particles are assumed to originate either upstream of the showerhead or from a specified position between the plates. The physical mechanisms controlling particle deposition and transport (inertia, diffusion, fluid drag, and external forces) are reviewed, with an emphasis on conditions encountered in semiconductor process tools (i.e., sub-atmospheric pressures and submicron particles). Isothermal flow is assumed, although small temperature differences are allowed to drive particle thermophoresis. Numerical solutions of the flow field are presented which agree with an analytic, creeping-flow expression for Re < 4. Deposition is quantified by use of a particle collection efficiency, which is defined as the fraction of particles in the reactor that deposit on the wafer. Analytic expressions for collection efficiency are presented for the limiting case where external forces control deposition (i.e., neglecting particle diffusion and inertia). Deposition from simultaneous particle diffusion and external forces is analyzed by an Eulerian formulation; for creeping flow and particles released from a planar trap, the analysis yields an analytic, integral expression for particle deposition based on process and particle properties. Deposition from simultaneous particle inertia and external forces is analyzed by a Lagrangian formulation, which can describe inertia-enhanced deposition resulting from particle acceleration in the showerhead. An approximate analytic expression is derived for particle velocity at the showerhead exit as a function of showerhead geometry, flow rate, and gas and particle properties. The particle showerhead-exit velocity is next used as an initial condition for particle transport between the plates to determine whether the particle deposits on the wafer, as a function of shower-head-exit particle velocity, the plate separation, flow rate, and gas and particle properties. Based on the numerical analysis, recommendations of best practices are presented that should help tool operators and designers reduce particle deposition in real tools. These guidelines are not intended to replace detailed calculations, but to provide the user with a general feel for inherently-clean practices.

  6. Comparison Between Synchronous and Asynchronous Implementation of Parallel Genetic Programming

    E-Print Network [OSTI]

    Fernandez, Thomas

    the processing time by using a coarse-grained model for parallelization and an asyn- chronous migration. The problem chosen to examine the parallel GP is a mobile robot navigation problem. The experimental results environments that were different from the original one. As a result, the substantial pro- cessing time

  7. Parallel MATLAB: Doing it Right Ron Choy , Alan Edelman

    E-Print Network [OSTI]

    Edelman, Alan

    1 Parallel MATLAB: Doing it Right Ron Choy , Alan Edelman Computer Science AI Laboratory-MIT Alliance November 15, 2003 DRAFT #12;2 Abstract MATLAB [20] is one of the most widely used mathematical Moler of Mathworks argued that there was no market at the time for a parallel MATLAB [26]. But times

  8. Parallel Adaptive Mesh Refinement and Redistribution on Distributed Memory Computers

    E-Print Network [OSTI]

    Bystroff, Chris

    Parallel Adaptive Mesh Refinement and Redistribution on Distributed Memory Computers C. ¨ Ozturan Polytechnic Institute Troy, NY 12181 Abstract A procedure to support parallel refinement and redistribution the required adjacency information. Mesh refinement is done by employing links back to the geometric

  9. Automatic Parallelization of Hand Written Automotive Engine Control

    E-Print Network [OSTI]

    Kasahara, Hironori

    Automatic Parallelization of Hand Written Automotive Engine Control Codes Using OSCAR Compiler Dan approach to realize the next- generation automobiles integrated control system. However, automotive-core processors for a long time. This paper proposes to parallelize an automotive engine crankshaft control

  10. Spatial Computing as Intensional Data Parallelism Antoine Spicher, Olivier Michel

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Spatial Computing as Intensional Data Parallelism Antoine Spicher, Olivier Michel LACL Universit to illustrate this statement. Keywords-spatial computing, collection, data-fields, data flow, declarative definition, intensionnal programming, stream, data parallelism I. SPATIAL COMPUTING It is customary to make

  11. On the Interplay of Parallelization, Program Performance, and Energy Consumption

    E-Print Network [OSTI]

    Marchal, Loris

    to either minimize the total energy consumption or minimize the energy-delay product. The impact of staticOn the Interplay of Parallelization, Program Performance, and Energy Consumption Sangyeun Cho through parallel execution of applications, suppressing the power and energy consumption remains an even

  12. Parallel Computation In Econometrics: A Simplified Approach Jurgen A. Doornik

    E-Print Network [OSTI]

    Wolfe, Patrick J.

    Parallel Computation In Econometrics: A Simplified Approach Jurgen A. Doornik , Neil Shephard Parallel computation has a long history in econometric computing, but is not at all wide spread. We believe optimization; Econometrics; High-performance computing; Matrix-programming language; Monte Carlo; MPI; Ox

  13. Application of Parallel Imaging to Murine Magnetic Resonance Imaging

    E-Print Network [OSTI]

    Chang, Chieh-Wei 1980-

    2012-09-21T23:59:59.000Z

    . This dissertation describes foundational level work to enable parallel imaging of mice on a 4.7 Tesla/40 cm bore research scanner. Reducing the size of the hardware setup associated with typical parallel imaging was an integral part of achieving the work, as animal...

  14. Exploiting parallelism within multidimensional multirate digital signal processing systems

    E-Print Network [OSTI]

    Peng, Dongming

    2004-09-30T23:59:59.000Z

    . . . . . . . . . . . 4 a. Non-RAM-based Architectural Designs of Wavelet- Based Systems . . . . . . . . . . . . . . . . . . . 5 b. Achieving Intra-iteration Parallelism in Mul- tidimensional Multirate Systems . . . . . . . . . . 6 c. Exploiting Inter... for zerotree construction : 30 5 The systolic and parallel wavelet lters integrating low-pass and high-pass ltering : : : : : : : : : : : : : : : : : : : : : : : : : : : : 33 6 The architecture of Transpose Unit (TU) : : : : : : : : : : : : : : : 34 7...

  15. A Methodology for the Derivation of Parallel Programs

    E-Print Network [OSTI]

    Goodman, Joy

    A Methodology for the Derivation of Parallel Programs Joy Goodman Department of Computer Science, University of Glasgow Abstract. I am currently developing a methodology for deriving paral­ lel programs from equational reasoning, a more efficient parallel program in a variety of languages and styles can be derived

  16. Parallel Imaging and Acceleration in the Johnson Noise Dominated Regime

    E-Print Network [OSTI]

    Rosen, Matthew S

    Parallel Imaging and Acceleration in the Johnson Noise Dominated Regime Cristen D. LaPierre1 receive coil in the parallel array. At low field, uncorrelated Johnson noise dominates, providing in the Johnson noise dominated regime. With the eight channel array, SENSE acceleration can be implemented

  17. Parallel Picoliter RT-PCR Assays Using Microfluidics

    E-Print Network [OSTI]

    Quake, Stephen R.

    Parallel Picoliter RT-PCR Assays Using Microfluidics Joshua S. Marcus,, W. French Anderson The development of microfluidic tools for high-throughput nucleic acid analysis has become a burgeoning area of research in the post-genome era. Here, we have developed a microfluidic chip to perform 72 parallel 450-p

  18. Analyzing Parallelism and Domain Similarities in the MAREC Patent Corpus

    E-Print Network [OSTI]

    Riezler, Stefan

    Analyzing Parallelism and Domain Similarities in the MAREC Patent Corpus Katharina W}@cl.uni-heidelberg.de Abstract. Statistical machine translation of patents requires large a- mounts of sentence-parallel data. Translations of patent text often exist for parts of the patent document, namely title, abstract and claims

  19. Parallel Formulations of Tree-Projection-Based Sequence Mining Algorithm

    E-Print Network [OSTI]

    Karypis, George

    , database projection algorithms, data mining, parallel processing This work was supported by NSF CCR-9972519 Institute. 1 #12;1 Introduction In recent years there has been an increased interest in using data miningParallel Formulations of Tree-Projection-Based Sequence Mining Algorithm Valerie Guralnik

  20. NDetermin: Inferring Nondeterministic Sequential Specifications for Parallelism Correctness

    E-Print Network [OSTI]

    Necula, George

    NDetermin: Inferring Nondeterministic Sequential Specifications for Parallelism Correctness Jacob and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post;NDetermin: Inferring Nondeterministic Sequential Specifications for Parallelism Correctness Jacob Burnim

  1. Parallel Finite Element Simulation of Tracer Injection in Oil Reservoirs

    E-Print Network [OSTI]

    Coutinho, Alvaro L. G. A.

    Parallel Finite Element Simulation of Tracer Injection in Oil Reservoirs Alvaro L.G.A. Coutinho In this work, parallel finite element techniques for the simulation of tracer injection in oil reservoirs. Supercomputers have made it possible to consider global reservoir effects which can not be represented using

  2. Parallel Processing Letters fc World Scientific Publishing Company

    E-Print Network [OSTI]

    Pallis, George

    that occurred on a production site of EGEE and the troubleshooting process for each case. Finally, we proposeParallel Processing Letters fc World Scientific Publishing Company FAILURE MANAGEMENT IN GRIDS infrastructure [1] in the context #12;Parallel Processing Letters of a drug-design effort [12], indicate

  3. Parallel architecture for real-time simulation. Master's thesis

    SciTech Connect (OSTI)

    Cockrell, C.D.

    1989-01-01T23:59:59.000Z

    This thesis is concerned with the development of a very fast and highly efficient parallel computer architecture for real-time simulation of continuous systems. Currently, several parallel processing systems exist that may be capable of executing a complex simulation in real-time. These systems are examined and the pros and cons of each system discussed. The thesis then introduced a custom-designed parallel architecture based upon The University of Alabama's OPERA architecture. Each component of this system is discussed and rationale presented for its selection. The problem selected, real-time simulation of the Space Shuttle Main Engine for the test and evaluation of the proposed architecture, is explored, identifying the areas where parallelism can be exploited and parallel processing applied. Results from the test and evaluation phase are presented and compared with the results of the same problem that has been processed on a uniprocessor system.

  4. Transparent runtime parallelization of the R scripting language

    SciTech Connect (OSTI)

    Yoginath, Srikanth B [ORNL

    2011-01-01T23:59:59.000Z

    Scripting languages such as R and Matlab are widely used in scientific data processing. As the data volume and the complexity of analysis tasks both grow, sequential data processing using these tools often becomes the bottleneck in scientific workflows. We describe pR, a runtime framework for automatic and transparent parallelization of the popular R language used in statistical computing. Recognizing scripting languages interpreted nature and data analysis codes use pattern, we propose several novel techniques: (1) applying parallelizing compiler technology to runtime, whole-program dependence analysis of scripting languages, (2) incremental code analysis assisted with evaluation results, and (3) runtime parallelization of file accesses. Our framework does not require any modification to either the source code or the underlying R implementation. Experimental results demonstrate that pR can exploit both task and data parallelism transparently and overall has better performance as well as scalability compared to an existing parallel R package that requires code modification.

  5. Does Anti-Parallel Spin Always Contain more Information ?

    E-Print Network [OSTI]

    Sibasish Ghosh; Anirban Roy; Ujjwal Sen

    2000-05-09T23:59:59.000Z

    We show that the Bloch vectors lying on any great circle is the largest set S(L) for which the parallel states |n,n> can always be transformed into the anti-parallel states |n,-n>. Thus more information about the Bloch vector is not extractable from |n,-n> than from |n,n> by any measuring strategy, for the Bloch vector belonging to S(L). Surprisingly, the largest set of Bloch vectors for which the corresponding qubits can be flipped is again S(L). We then show that probabilistic exact parallel to anti-parallel transformation is not possible if the corresponding anti-parallel spins span the whole Hilbert space of the two qubits. These considerations allow us to generalise a conjecture of Gisin and Popescu (Phys. Rev. Lett. 83 432 (1999)).

  6. Broadcasting collective operation contributions throughout a parallel computer

    DOE Patents [OSTI]

    Faraj, Ahmad (Rochester, MN)

    2012-02-21T23:59:59.000Z

    Methods, systems, and products are disclosed for broadcasting collective operation contributions throughout a parallel computer. The parallel computer includes a plurality of compute nodes connected together through a data communications network. Each compute node has a plurality of processors for use in collective parallel operations on the parallel computer. Broadcasting collective operation contributions throughout a parallel computer according to embodiments of the present invention includes: transmitting, by each processor on each compute node, that processor's collective operation contribution to the other processors on that compute node using intra-node communications; and transmitting on a designated network link, by each processor on each compute node according to a serial processor transmission sequence, that processor's collective operation contribution to the other processors on the other compute nodes using inter-node communications.

  7. Symmetry related dynamics in parallel shear flows

    E-Print Network [OSTI]

    Tobias Kreilos; Stefan Zammert; Bruno Eckhardt

    2014-04-23T23:59:59.000Z

    Parallel shear flows come with continuous symmetries of translation in the downstream and spanwise direction. As a consequence, flow states that differ in their spanwise or downstream location but are otherwise identical are dynamically equivalent. In the case of travelling waves, this trivial degree of freedom can be removed by going to a frame of reference that moves with the state, thereby turning the travelling wave in the laboratory frame to a fixed point in the comoving frame of reference. We here discuss a general method by which the translational displacements can be removed also for more complicated and dynamically active states and demonstrate its application for several examples. For flows states in the asymptotic suction boundary layer we show that in the case of the long-period oscillatory edge state we can find local phase speeds which remove the fast oscillations and reveal the slow vortex dynamics underlying the burst phenomenon. For spanwise translating states we show that the method removes the drift but not the dynamical events that cause the big spanwise displacement. For a turbulent case we apply the method to the spanwise shifts and find slow components that are correlated over very long times. Calculations for plane Poiseuille flow show that the long correlations in the transverse motions are not special to the asymptotic suction boundary layer.

  8. THE ELM SURVEY. V. MERGING MASSIVE WHITE DWARF BINARIES

    SciTech Connect (OSTI)

    Brown, Warren R.; Kenyon, Scott J. [Smithsonian Astrophysical Observatory, 60 Garden St, Cambridge, MA 02138 (United States); Kilic, Mukremin; Gianninas, A. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Norman, OK, 73019 (United States); Allende Prieto, Carlos, E-mail: wbrown@cfa.harvard.edu, E-mail: skenyon@cfa.harvard.edu, E-mail: kilic@ou.edu, E-mail: alexg@nhn.ou.edu, E-mail: callende@iac.es [Instituto de Astrofisica de Canarias, E-38205, La Laguna, Tenerife (Spain)

    2013-05-20T23:59:59.000Z

    We present the discovery of 17 low-mass white dwarfs (WDs) in short-period (P {<=} 1 day) binaries. Our sample includes four objects with remarkable log g {approx_equal} 5 surface gravities and orbital solutions that require them to be double degenerate binaries. All of the lowest surface gravity WDs have metal lines in their spectra implying long gravitational settling times or ongoing accretion. Notably, six of the WDs in our sample have binary merger times <10 Gyr. Four have {approx}>0.9 M{sub Sun} companions. If the companions are massive WDs, these four binaries will evolve into stable mass transfer AM CVn systems and possibly explode as underluminous supernovae. If the companions are neutron stars, then these may be millisecond pulsar binaries. These discoveries increase the number of detached, double degenerate binaries in the ELM Survey to 54; 31 of these binaries will merge within a Hubble time.

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

    SciTech Connect (OSTI)

    Cure, M. [Departamento de Fisica y Astronomia, Facultad de Ciencias, Universidad de Valparaiso, Av. Gran Bretana 1111, Casilla 5030, Valparaiso (Chile); Cidale, L. [Departamento de Espectroscopia, Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata (UNLP), Paseo del Bosque S/N, 1900 La Plata (Argentina); Rial, D. F., E-mail: michel.cure@uv.cl, E-mail: lydia@fcaglp.unlp.edu.ar, E-mail: drial@dm.uba.ar [Departamento de Matematicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina)

    2012-10-01T23:59:59.000Z

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

  10. Numerical Modeling of Charged Black Holes with Massive Dilaton

    E-Print Network [OSTI]

    T. L. Boyadjiev; P. P. Fiziev

    2003-11-28T23:59:59.000Z

    In this paper the static, spherically symmetric and electrically charged black hole solutions in Einstein-Born-Infeld gravity with massive dilaton are investigated numerically. The Continuous Analog of Newton Method (CANM) is used to solve the corresponding nonlinear multipoint boundary value problems (BVPs). The linearized BVPs are solved numerically by means of collocation scheme of fourth order. A special class of solutions are the extremal ones. We show that the extremal horizons within the framework of the model satisfy some nonlinear system of algebraic equations. Depending on the charge $q$ and dilaton mass $\\gamma$, the black holes can have no more than three horizons. This allows us to construct some Hermite polynomial of third order. Its real roots describe the number, the type and other characteristics of the horizons.

  11. Consistent metric combinations in cosmology of massive bigravity

    E-Print Network [OSTI]

    Henrik Nersisyan; Yashar Akrami; Luca Amendola

    2015-02-13T23:59:59.000Z

    Massive bigravity models are interesting alternatives to standard cosmology. In most cases however these models have been studied for a simplified scenario in which both metrics take homogeneous and isotropic forms (Friedmann-Lema\\^{i}tre-Robertson-Walker; FLRW) with the same spatial curvatures. The interest to consider more general geometries arises in particular in view of the difficulty so far encountered in building stable cosmological solutions with homogeneous and isotropic metrics. Here we consider a number of cases in which the two metrics take more general forms, namely FLRW with different spatial curvatures, Lema\\^{i}tre, Lema\\^{i}tre-Tolman-Bondi (LTB), and Bianchi I, as well as cases where only one metric is linearly perturbed. We discuss possible consistent combinations and find that only some special cases of FLRW-Lema\\^{i}tre, LTB-LTB and FLRW-Bianchi I combinations give consistent, non-trivial solutions.

  12. Asymptotically anti-de Sitter spacetimes in topologically massive gravity

    SciTech Connect (OSTI)

    Henneaux, Marc [Centro de Estudios Cientificos (CECS), Casilla 1469, Valdivia (Chile); Physique theorique et mathematique, Universite Libre de Bruxelles and International Solvay Institutes, ULB Campus Plaine C.P. 231, B-1050 Bruxelles (Belgium); Martinez, Cristian; Troncoso, Ricardo [Centro de Estudios Cientificos (CECS), Casilla 1469, Valdivia (Chile); Centro de Ingenieria de la Innovacion del CECS (CIN), Valdivia (Chile)

    2009-04-15T23:59:59.000Z

    We consider asymptotically anti-de Sitter spacetimes in three-dimensional topologically massive gravity with a negative cosmological constant, for all values of the mass parameter {mu} ({mu}{ne}0). We provide consistent boundary conditions that accommodate the recent solutions considered in the literature, which may have a slower falloff than the one relevant for general relativity. These conditions are such that the asymptotic symmetry is in all cases the conformal group, in the sense that they are invariant under asymptotic conformal transformations and that the corresponding Virasoro generators are finite. It is found that, at the chiral point |{mu}l|=1 (where l is the anti-de Sitter radius), allowing for logarithmic terms (absent for general relativity) in the asymptotic behavior of the metric makes both sets of Virasoro generators nonzero even though one of the central charges vanishes.

  13. New Massive Gravity and AdS{sub 4} Counterterms

    SciTech Connect (OSTI)

    Jatkar, Dileep P. [Harish-Chandra Research Institute, Chhatnag Road, Jhusi, Allahabad, 211019 (India); Sinha, Aninda [Centre for High Energy Physics, Indian Institute of Science, C. V. Raman Avenue, Bangalore 560012 (India)

    2011-04-29T23:59:59.000Z

    We show that the recently proposed Dirac-Born-Infeld extension of new massive gravity emerges naturally as a counterterm in four-dimensional anti-de Sitter space (AdS{sub 4}). The resulting on-shell Euclidean action is independent of the cutoff at zero temperature. We also find that the same choice of counterterm gives the usual area law for the AdS{sub 4} Schwarzschild black hole entropy in a cutoff-independent manner. The parameter values of the resulting counterterm action correspond to a c=0 theory in the context of the duality between AdS{sub 3} gravity and two-dimensional conformal field theory. We rewrite this theory in terms of the gauge field that is used to recast 3D gravity as a Chern-Simons theory.

  14. Supersymmetric Warped AdS in Extended Topologically Massive Supergravity

    E-Print Network [OSTI]

    Nihat Sadik Deger; Ali Kaya; Henning Samtleben; Ergin Sezgin

    2014-05-22T23:59:59.000Z

    We determine the most general form of off-shell N=(1,1) supergravity field configurations in three dimensions by requiring that at least one off-shell Killing spinor exists. We then impose the field equations of the topologically massive off-shell supergravity and find a class of solutions whose properties crucially depend on the norm of the auxiliary vector field. These are spacelike-squashed and timelike-stretched AdS_3 for the spacelike and timelike norms, respectively. At the transition point where the norm vanishes, the solution is null warped AdS_3. This occurs when the coefficient of the Lorentz-Chern-Simons term is related to the AdS radius by $\\mu\\ell=2$. We find that the spacelike-squashed AdS_3 can be modded out by a suitable discrete subgroup of the isometry group, yielding an extremal black hole solution which avoid closed timelike curves.

  15. New Massive Gravity and AdS_4 counterterms

    E-Print Network [OSTI]

    Dileep P. Jatkar; Aninda Sinha

    2011-04-06T23:59:59.000Z

    We show that the recently proposed DBI extension of new massive gravity emerges naturally as a counterterm in AdS$_4$. The resulting on-shell Euclidean action is independent of the cut-off at zero temperature. We also find that the same choice of counterterm gives the usual area law for the AdS$_4$ Schwarzschild black hole entropy in a cut-off independent manner. The parameter values of the resulting counterterm action correspond to a $c=0$ theory in the context of AdS$_3$/CFT$_2$. We rewrite this theory in terms of the gauge field that is used to recast 3D gravity as a Chern-Simons theory.

  16. Massive Social Network Analysis: Mining Twitter for Social Good

    SciTech Connect (OSTI)

    Ediger, David; Jiang, Karl; Riedy, Edward J.; Bader, David A.; Corley, Courtney D.; Farber, Robert M.; Reynolds, William

    2010-10-11T23:59:59.000Z

    Social networks produce an enormous quantity of data. Facebook consists of over 400 million active users sharing over 5 billion pieces of information each month. Analyzing this vast quantity of unstructured data presents challenges for software and hardware. We present GraphCT, a Graph Characterization Tooklit for massive graphs representing social network data. On a 128-processor Cray XMT, GraphCT estimates the betweenness centrality of an artificially generated (R-MAT) 537 million vertex, 8.6 billion edge graph in 55 minutes. We use GraphCT to analyze public data from Twitter, a microblogging network. Twitter's message connections appear primarily tree-structured as a news dissemination system. Within the public data, however, are clusters of conversations. Using GraphCT, we can rank actors within these conversations and help analysts focus attention on a much smaller data subset.

  17. Flavor Mixing and CP Violation of Massive Neutrinos

    E-Print Network [OSTI]

    Zhi-zhong Xing

    2004-11-26T23:59:59.000Z

    We present an overview of recent progress in the phenomenological study of neutrino masses, lepton flavor mixing and CP violation. We concentrate on the model-independent properties of massive neutrinos, both in vacuum and in matter. Current experimental constraints on the neutrino mass spectrum and the lepton flavor mixing parameters are summarized. The Dirac- and Majorana-like phases of CP violation, which are associated respectively with the long-baseline neutrino oscillations and the neutrinoless double beta decay, are discussed in detail. The seesaw mechanism, the leptogenesis scenario and the strategies to construct lepton mass matrices are briefly described. The features of flavor mixing between one sterile neutrino and three active neutrinos are also explored.

  18. Bousso entropy bound for ideal gas of massive particles

    E-Print Network [OSTI]

    Jan Gersl

    2008-04-13T23:59:59.000Z

    The Bousso entropy bound is investigated for static spherically symmetric configurations of ideal gas with Bose-Einstein and Fermi-Dirac distribution function. Gas of massive particles is considered. The paper is continuation of the previous work concerning the massless case. Special attention is devoted to lightsheets generated by spheres. Conditions under which the Bousso bound can be violated are discussed and it is shown that a possible violating region cannot be arbitrarily large and that it is contained inside a sphere of unit Planck radius if the number of independent spin states $g_s$ is small enough. It is also shown that the central temperature must exceed the Planck temperature in order to get a violation of the Bousso bound for $g_s$ not too large. The situation for higher-dimensional spacetimes is also discussed and the FMW conditions are investigated.

  19. Non-thermal radiation from a runaway massive star

    E-Print Network [OSTI]

    Romero, Gustavo E; Peri, Cintia S; Marti, Josep; Araudo, Anabella T

    2010-01-01T23:59:59.000Z

    We present a study of the radio emission from a massive runaway star. The star forms a bow shock that is clearly observed in the infrared. We have performed VLA observations under the assumption that the reverse shock in the stellar wind might accelerate charged particles up to relativistic energies. Non-thermal radio emission of synchrotron origin has been detected, confirming the hypothesis. We have then modeled the system and we predict a spectral energy distribution that extends up to gamma-rays. Under some simplifying assumptions, we find that the intensity at high energies is too low to be detected by current instruments, but the future Cherenkov Telescope Array might detect the source.

  20. DWARF GALAXIES WITH OPTICAL SIGNATURES OF ACTIVE MASSIVE BLACK HOLES

    SciTech Connect (OSTI)

    Reines, Amy E. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Geha, Marla, E-mail: areines@nrao.edu [Department of Astronomy, Yale University, New Haven, CT 06520 (United States)

    2013-10-01T23:59:59.000Z

    We present a sample of 151 dwarf galaxies (10{sup 8.5} ?< M{sub *} ?< 10{sup 9.5} M{sub ?}) that exhibit optical spectroscopic signatures of accreting massive black holes (BHs), increasing the number of known active galaxies in this stellar-mass range by more than an order of magnitude. Utilizing data from the Sloan Digital Sky Survey Data Release 8 and stellar masses from the NASA-Sloan Atlas, we have systematically searched for active BHs in ?25,000 emission-line galaxies with stellar masses comparable to the Magellanic Clouds and redshifts z < 0.055. Using the narrow-line [O III]/H? versus [N II]/H? diagnostic diagram, we find photoionization signatures of BH accretion in 136 galaxies, a small fraction of which also exhibit broad H? emission. For these broad-line active galactic nucleus (AGN) candidates, we estimate BH masses using standard virial techniques and find a range of 10{sup 5} ?< M{sub BH} ?< 10{sup 6} M{sub ?} and a median of M{sub BH} ? 2 × 10{sup 5} M{sub ?}. We also detect broad H? in 15 galaxies that have narrow-line ratios consistent with star-forming galaxies. Follow-up observations are required to determine if these are true type 1 AGN or if the broad H? is from stellar processes. The median absolute magnitude of the host galaxies in our active sample is M{sub g} = –18.1 mag, which is ?1-2 mag fainter than previous samples of AGN hosts with low-mass BHs. This work constrains the smallest galaxies that can form a massive BH, with implications for BH feedback in low-mass galaxies and the origin of the first supermassive BH seeds.

  1. Massive stars: Feedback effects in the local universe

    E-Print Network [OSTI]

    M. S. Oey; C. J. Clarke

    2007-03-02T23:59:59.000Z

    We examine self-consistent parameterizations of the high-mass stellar population and resulting feedback, including mechanical, radiative, and chemical feedback, as we understand them locally. To date, it appears that the massive star population follows simple power-law clustering that extends down to individual field OB stars, and the robust stellar IMF seems to have a constant upper-mass limit. These properties result in specific patterns in the HII region LF and ionization of the diffuse, warm ionized medium. The resulting SNe generate superbubbles whose size distribution is also described by a simple power law, and from which a galaxy's porosity parameter is easily derived. A critical star-formation threshold can then be estimated, above which the escape of Lyman continuum photons, hot gas, and nucleosynthetic products is predicted. A first comparison with a large H-alpha sample of galaxies is broadly consistent with this prediction, and suggests that ionizing photons likely escapes from starburst galaxies. The superbubble size distribution also offers a basis for a Simple Inhomogeneous Model for galactic chemical evolution, which is especially relevant to metal-poor systems and instantaneous metallicity distributions. This model offers an alternative interpretation of the Galactic halo metallicity distribution and emphasizes the relative importance of star-formation intensity, in addition to age, in a system's evolution. The fraction of zero-metallicity, Population III stars is easily predicted for any such model. We emphasize that all these phenomena can be modeled in a simple, analytic framework over an extreme range in scale, offering powerful tools for understanding the role of massive stars in the cosmos. (Abridged)

  2. ComSIS Vol. 1, No. 1, February 2004 75 Network Models of Massive Datasets

    E-Print Network [OSTI]

    Butenko, Sergiy

    ComSIS Vol. 1, No. 1, February 2004 75 Network Models of Massive Datasets Vladimir Boginski 1 overview of the methodology of modeling massive datasets arising in various applications as networks. This approach is often useful for extracting non-trivial information from the datasets by applying standard

  3. Analyzing Massive Astrophysical Datasets: Can Pig/Hadoop or a Relational DBMS Help?

    E-Print Network [OSTI]

    Anderson, Richard

    Analyzing Massive Astrophysical Datasets: Can Pig/Hadoop or a Relational DBMS Help? Sarah Loebman1 distributed DBMS and in the Pig/Hadoop system. We compare the performance of the tools to each other of subatomic particles to the evolution of the universe. These simulations produce an ever more massive amount

  4. Dynamics of a Massive Piston in an Ideal Gas N. Chernov1,4

    E-Print Network [OSTI]

    Dynamics of a Massive Piston in an Ideal Gas N. Chernov1,4 , J. L. Lebowitz2,4 , and Ya. Sinai3 January 1, 2003 Abstract We study a dynamical system consisting of a massive piston in a cubical con- tainer of large size L filled with an ideal gas. The piston has mass M L2 and undergoes elastic

  5. Motion of Spin 1/2 Massive Particle in a Curved Spacetime

    E-Print Network [OSTI]

    A. T. Muminov

    2007-09-28T23:59:59.000Z

    Quasi-classical picture of motion of spin 1/2 massive particle in a curved spacetime is built on base of simple Lagrangian model. The one is constructed due to analogy with Lagrangian of massive vector particle. Equations of motion and spin propagation coincide with Papapetrou equations describing dynamic of classical spinning particle in a curved spacetime.

  6. Evolution of massive Be and Oe stars at low metallicity towards the Long Gamma Ray bursts

    E-Print Network [OSTI]

    Evolution of massive Be and Oe stars at low metallicity towards the Long Gamma Ray bursts C and massive stars, and the theoretical predictions of the characteristics must have the long gamma-ray burst of that document deals with the long soft gamma ray bursts (here type 2 bursts) and their possible relationship

  7. Massive spin-2 and spin-1/2 no hair theorems for stationary axisymmetric black holes

    E-Print Network [OSTI]

    Sourav Bhattacharya; Amitabha Lahiri

    2012-10-09T23:59:59.000Z

    We present a proof of the no hair theorems corresponding to free massive non-perturbative Pauli-Fierz spin-2 and perturbative massive spin-1/2 fields for stationary axisymmetric de Sitter black hole spacetimes of dimension four with two commuting Killing vector fields. The applicability of these results for asymptotically flat and anti-de Sitter spacetimes are also discussed.

  8. Automatic Thread Distribution For Nested Parallelism In OpenMP OpenMP is becoming the standard programming model for sharedmemory parallel architectures. One of its most inter-

    E-Print Network [OSTI]

    Corbalan, Julita

    Automatic Thread Distribution For Nested Parallelism In OpenMP Abstract OpenMP is becoming in the language is the support for nested parallelism. Previous research and parallelization experiences have shown the benefits of using nested parallelism as an alternative to combining several programming models

  9. AutoAuto--tuned nested parallelism: a way totuned nested parallelism: a way to reduce the execution time of scientificreduce the execution time of scientific

    E-Print Network [OSTI]

    Giménez, Domingo

    AutoAuto--tuned nested parallelism: a way totuned nested parallelism: a way to reduce the execution problems AutoAuto--tuned nested parallelism: a way to reduce the execution time of scientific software in NUMA systemstuned nested parallelism: a way to reduce the execution time of scientific software in NUMA

  10. Xyce parallel electronic simulator : users' guide. Version 5.1.

    SciTech Connect (OSTI)

    Mei, Ting; Rankin, Eric Lamont; Thornquist, Heidi K.; Santarelli, Keith R.; Fixel, Deborah A.; Coffey, Todd Stirling; Russo, Thomas V.; Schiek, Richard Louis; Keiter, Eric Richard; Pawlowski, Roger Patrick

    2009-11-01T23:59:59.000Z

    This manual describes the use of the Xyce Parallel Electronic Simulator. Xyce has been designed as a SPICE-compatible, high-performance analog circuit simulator, and has been written to support the simulation needs of the Sandia National Laboratories electrical designers. This development has focused on improving capability over the current state-of-the-art in the following areas: (1) Capability to solve extremely large circuit problems by supporting large-scale parallel computing platforms (up to thousands of processors). Note that this includes support for most popular parallel and serial computers. (2) Improved performance for all numerical kernels (e.g., time integrator, nonlinear and linear solvers) through state-of-the-art algorithms and novel techniques. (3) Device models which are specifically tailored to meet Sandia's needs, including some radiation-aware devices (for Sandia users only). (4) Object-oriented code design and implementation using modern coding practices that ensure that the Xyce Parallel Electronic Simulator will be maintainable and extensible far into the future. Xyce is a parallel code in the most general sense of the phrase - a message passing parallel implementation - which allows it to run efficiently on the widest possible number of computing platforms. These include serial, shared-memory and distributed-memory parallel as well as heterogeneous platforms. Careful attention has been paid to the specific nature of circuit-simulation problems to ensure that optimal parallel efficiency is achieved as the number of processors grows. The development of Xyce provides a platform for computational research and development aimed specifically at the needs of the Laboratory. With Xyce, Sandia has an 'in-house' capability with which both new electrical (e.g., device model development) and algorithmic (e.g., faster time-integration methods, parallel solver algorithms) research and development can be performed. As a result, Xyce is a unique electrical simulation capability, designed to meet the unique needs of the laboratory.

  11. FORMATION OF MASSIVE MOLECULAR CLOUD CORES BY CLOUD-CLOUD COLLISION

    SciTech Connect (OSTI)

    Inoue, Tsuyoshi [Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara, Kanagawa 252-5258 (Japan); Fukui, Yasuo, E-mail: inouety@phys.aoyama.ac.jp [Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)

    2013-09-10T23:59:59.000Z

    Recent observations of molecular clouds around rich massive star clusters including NGC 3603, Westerlund 2, and M20 revealed that the formation of massive stars could be triggered by a cloud-cloud collision. By using three-dimensional, isothermal, magnetohydrodynamics simulations with the effect of self-gravity, we demonstrate that massive, gravitationally unstable, molecular cloud cores are formed behind the strong shock waves induced by cloud-cloud collision. We find that the massive molecular cloud cores have large effective Jeans mass owing to the enhancement of the magnetic field strength by shock compression and turbulence in the compressed layer. Our results predict that massive molecular cloud cores formed by the cloud-cloud collision are filamentary and threaded by magnetic fields perpendicular to the filament.

  12. Tile-based Level of Detail for the Parallel Age

    SciTech Connect (OSTI)

    Niski, K; Cohen, J D

    2007-08-15T23:59:59.000Z

    Today's PCs incorporate multiple CPUs and GPUs and are easily arranged in clusters for high-performance, interactive graphics. We present an approach based on hierarchical, screen-space tiles to parallelizing rendering with level of detail. Adapt tiles, render tiles, and machine tiles are associated with CPUs, GPUs, and PCs, respectively, to efficiently parallelize the workload with good resource utilization. Adaptive tile sizes provide load balancing while our level of detail system allows total and independent management of the load on CPUs and GPUs. We demonstrate our approach on parallel configurations consisting of both single PCs and a cluster of PCs.

  13. TECA: A Parallel Toolkit for Extreme Climate Analysis

    SciTech Connect (OSTI)

    Prabhat, Mr; Ruebel, Oliver; Byna, Surendra; Wu, Kesheng; Li, Fuyu; Wehner, Michael; Bethel, E. Wes

    2012-03-12T23:59:59.000Z

    We present TECA, a parallel toolkit for detecting extreme events in large climate datasets. Modern climate datasets expose parallelism across a number of dimensions: spatial locations, timesteps and ensemble members. We design TECA to exploit these modes of parallelism and demonstrate a prototype implementation for detecting and tracking three classes of extreme events: tropical cyclones, extra-tropical cyclones and atmospheric rivers. We process a modern TB-sized CAM5 simulation dataset with TECA, and demonstrate good runtime performance for the three case studies.

  14. Endpoint-based parallel data processing with non-blocking collective instructions in a parallel active messaging interface of a parallel computer

    DOE Patents [OSTI]

    Archer, Charles J; Blocksome, Michael A; Cernohous, Bob R; Ratterman, Joseph D; Smith, Brian E

    2014-11-11T23:59:59.000Z

    Endpoint-based parallel data processing with non-blocking collective instructions in a PAMI of a parallel computer is disclosed. The PAMI is composed of data communications endpoints, each including a specification of data communications parameters for a thread of execution on a compute node, including specifications of a client, a context, and a task. The compute nodes are coupled for data communications through the PAMI. The parallel application establishes a data communications geometry specifying a set of endpoints that are used in collective operations of the PAMI by associating with the geometry a list of collective algorithms valid for use with the endpoints of the geometry; registering in each endpoint in the geometry a dispatch callback function for a collective operation; and executing without blocking, through a single one of the endpoints in the geometry, an instruction for the collective operation.

  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)

    2010-10-01T23:59:59.000Z

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

  16. DARK MATTER HALO PROFILES OF MASSIVE CLUSTERS: THEORY VERSUS OBSERVATIONS

    SciTech Connect (OSTI)

    Bhattacharya, Suman; Habib, Salman; Heitmann, Katrin [High Energy Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States)] [High Energy Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Vikhlinin, Alexey [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)] [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-03-20T23:59:59.000Z

    Dark-matter-dominated cluster-scale halos act as an important cosmological probe and provide a key testing ground for structure formation theory. Focusing on their mass profiles, we have carried out (gravity-only) simulations of the concordance {Lambda}CDM cosmology, covering a mass range of 2 Multiplication-Sign 10{sup 12} to 2 Multiplication-Sign 10{sup 15} h {sup -1} M{sub Sun} and a redshift range of z = 0-2, while satisfying the associated requirements of resolution and statistical control. When fitting to the Navarro-Frenk-White profile, our concentration-mass (c-M) relation differs in normalization and shape in comparison to previous studies that have limited statistics in the upper end of the mass range. We show that the flattening of the c-M relation with redshift is naturally expressed if c is viewed as a function of the peak height parameter, {nu}. Unlike the c-M relation, the slope of the c-{nu} relation is effectively constant over the redshift range z = 0-2, while the amplitude varies by {approx}30% for massive clusters. This relation is, however, not universal: using a simulation suite covering the allowed wCDM parameter space, we show that the c-{nu} relation varies by about {+-}20% as cosmological parameters are varied. At fixed mass, the c(M) distribution is well fit by a Gaussian with {sigma}{sub c}/(c) {approx_equal} 1/3, independent of the radius at which the concentration is defined, the halo dynamical state, and the underlying cosmology. We compare the {Lambda}CDM predictions with observations of halo concentrations from strong lensing, weak lensing, galaxy kinematics, and X-ray data, finding good agreement for massive clusters (M{sub vir} > 4 Multiplication-Sign 10{sup 14} h {sup -1} M{sub Sun }), but with some disagreements at lower masses. Because of uncertainty in observational systematics and modeling of baryonic physics, the significance of these discrepancies remains unclear.

  17. Thread Scheduling Mechanisms for Multiple-Context Parallel Processors

    E-Print Network [OSTI]

    Fiske, James A. Stuart

    1995-06-01T23:59:59.000Z

    Scheduling tasks to efficiently use the available processor resources is crucial to minimizing the runtime of applications on shared-memory parallel processors. One factor that contributes to poor processor utilization ...

  18. Distinguishable patterns of competition, collusion, and parallel action

    E-Print Network [OSTI]

    Smith, James L.

    2003-01-01T23:59:59.000Z

    Alternative market structures are distinguishable by the degree of parallel action exhibited by producers. We show that the correlation between output levels varies systematically with the degree of interdependence among ...

  19. Design and evaluation of the Hamal parallel computer

    E-Print Network [OSTI]

    Grossman, J. P., 1973-

    2003-01-01T23:59:59.000Z

    Parallel shared-memory machines with hundreds or thousands of processor-memory nodes have been built; in the future we will see machines with millions or even billions of nodes. Associated with such large systems is a new ...

  20. Circuit and bond polytopes on series-parallel graphs$

    E-Print Network [OSTI]

    2014-07-10T23:59:59.000Z

    Jul 10, 2014 ... M0 = IS, for some star decomposition S of G, and Mi?Ni is a cut of G, for i = 1,..., k. 2. Circuit polytope on series-parallel graphs. Given a graph G ...

  1. Design and Evaluation of the Hamal Parallel Computer

    E-Print Network [OSTI]

    Grossman, J.P.

    2002-12-05T23:59:59.000Z

    Parallel shared-memory machines with hundreds or thousands of processor-memory nodes have been built; in the future we will see machines with millions or even billions of nodes. Associated with such large systems is a new ...

  2. Control system design for a parallel hybrid electric vehicle

    E-Print Network [OSTI]

    Buntin, David Leighton

    1994-01-01T23:59:59.000Z

    This thesis addresses the design of control systems for a parallel hybrid electric drive train which is an alternative to conventional passenger vehicles. The principle components of the drive train are a small internal combustion engine...

  3. Optimized control studies of a parallel hybrid electric vehicle

    E-Print Network [OSTI]

    Bougler, Benedicte Bernadette

    1995-01-01T23:59:59.000Z

    This thesis addresses the development of a control scheme to maximize automobile fuel economy and battery state-of-charge (SOC) while meeting exhaust emission standards for parallel hybrid electric vehicles, which are an alternative to conventional...

  4. RF Pulse Design for Parallel Excitation in Magnetic Resonance Imaging

    E-Print Network [OSTI]

    Liu, Yinan

    2012-07-16T23:59:59.000Z

    Parallel excitation is an emerging technique to improve or accelerate multi-dimensional spatially selective excitations in magnetic resonance imaging (MRI) using multi-channel transmit arrays. The technique has potential in many applications...

  5. Implementation and testing of a parallel layer peeling algorithm

    E-Print Network [OSTI]

    Gandapur, Tasneem Kausar

    2012-06-07T23:59:59.000Z

    implementation was considered because of the anticipated speedup in the solution of the problem under consideration. The algorithm was implemented on an NCUBE 2 machine, with a total of sixty-four processors. Two variations of the parallel algorithm were...

  6. Design and implementation of parallel simulation ranking and selection procedures.

    E-Print Network [OSTI]

    Wu, Yang

    2013-01-01T23:59:59.000Z

    ??Conventional simulation ranking-and-selection(R&S) procedures are designed and implemented for serial computing environment. However, today's growth of computing power relies more on parallelism rather than faster… (more)

  7. Natural convection flows in parallel connected vertical channels with boiling

    E-Print Network [OSTI]

    Eselgroth, Peter Ward

    1967-01-01T23:59:59.000Z

    The steady-state flow configuration in an array of parallel heated channels is examined with the objective of predicting the behavior of a reactor during a loss of flow accident. A method of combining the results of single ...

  8. A parallel hypothesis method of autonomous underwater vehicle navigation

    E-Print Network [OSTI]

    LaPointe, Cara Elizabeth Grupe

    2009-01-01T23:59:59.000Z

    This research presents a parallel hypothesis method for autonomous underwater vehicle navigation that enables a vehicle to expand the operating envelope of existing long baseline acoustic navigation systems by incorporating ...

  9. Scheduling on the MasPar SIMD parallel computer

    E-Print Network [OSTI]

    Perkins, Keith Douglas

    1995-01-01T23:59:59.000Z

    This thesis studies the feasibility of a task scheduler for a parallel operating system. After analyzing several task scheduling algorithms, the highest level first algorithm was chosen. This algorithm has been empirically found to build schedules...

  10. Some applications of pipelining techniques in parallel scientific computing

    E-Print Network [OSTI]

    Deng, Yuanhua

    1996-01-01T23:59:59.000Z

    In this thesis, we study the applicability of pipelining techniques to the development of parallel algorithms for scientific computation. General principles for pipelining techniques are discussed and two applications, Gram-Schmidt orthogonalization...

  11. Global Optimization and Parallelization of Integrity Constraint Checks

    E-Print Network [OSTI]

    Neumaier, Arnold

    . The primary objective of global opti­ mization is to produce a global execution plan for a group ngine ( ) ice i c e parallel generation of evaluation plans Figure 1: Basic concept of integrity

  12. The Next-Generation Massively Parallel Reactive Flow and Transport Code PFLOTRAN: Application to CO2 Storage in Saline Aquifers P. Lichtner

    E-Print Network [OSTI]

    Mills, Richard

    to investigate sequestration of CO2 in vari- ous geologic media including depleted oil reservoirs and saline

  13. Electrostatically focused addressable field emission array chips (AFEA's) for high-speed massively parallel maskless digital E-beam direct write lithography and scanning electron microscopy

    DOE Patents [OSTI]

    Thomas, Clarence E. (Knoxville, TN); Baylor, Larry R. (Farragut, TN); Voelkl, Edgar (Oak Ridge, TN); Simpson, Michael L. (Knoxville, TN); Paulus, Michael J. (Knoxville, TN); Lowndes, Douglas H. (Knoxville, TN); Whealton, John H. (Oak Ridge, TN); Whitson, John C. (Clinton, TN); Wilgen, John B. (Oak Ridge, TN)

    2002-12-24T23:59:59.000Z

    Systems and methods are described for addressable field emission array (AFEA) chips. A method of operating an addressable field-emission array, includes: generating a plurality of electron beams from a pluralitly of emitters that compose the addressable field-emission array; and focusing at least one of the plurality of electron beams with an on-chip electrostatic focusing stack. The systems and methods provide advantages including the avoidance of space-charge blow-up.

  14. Parallel-Flow-Shear Driven Low-Frequency Plasma Instability

    SciTech Connect (OSTI)

    Ishiguro, Seiji [Theory and Computer Simulation Center, National Institute for Fusion Science, Toki-shi, Gifu 509-5292 (Japan); Matsumoto, Noriaki; Kaneko, Toshiro; Hatakeyama, Rikizo [Department of Electronic Engineering, Tohoku University, Sendai 980-8579 (Japan)

    2004-12-01T23:59:59.000Z

    Full three dimensional Particle-in-Cell (PIC) simulations are performed in order to investigate effects of field-aligned (parallel) ion flow shears on low-frequency plasma instabilities. It is shown that the parallel ion flow velocity shear can induce the ion-acoustic instability, even when the ion flow velocity is so small that the instability can not take place. Simulation results are consistent with the analysis based on the local theory.

  15. Parallel Routing Algorithms for Nonblocking Electronic and Photonic Switching Networks

    E-Print Network [OSTI]

    Lu, Enyue "Annie"

    Parallel Routing Algorithms for Nonblocking Electronic and Photonic Switching Networks Enyue Lu for the RNB networks of complexities ranging from OðN lg N� to OðN1:5 lg N� crosspoints and parallel algorithms that run in Oðminfd� lg N; ffiffiffiffiffi N p g� time for the SNB networks of OðN1:5 lg N�

  16. final report for Center for Programming Models for Scalable Parallel Computing

    SciTech Connect (OSTI)

    Johnson, Ralph E

    2013-04-10T23:59:59.000Z

    This is the final report of the work on parallel programming patterns that was part of the Center for Programming Models for Scalable Parallel Computing

  17. Embracing diversity : improving performance for parallel storage systems built with heterogeneous disks

    E-Print Network [OSTI]

    Bruno, Gregory DuVall

    2008-01-01T23:59:59.000Z

    Figure I.2: Parallel Storage System Architecture FigureHeterogeneous Parallel Storage Systems . . . . . B. Modeldisks on a multimedia storage system with random data

  18. E-Print Network 3.0 - accelerated scalable parallel Sample Search...

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

    and excellent suitability for parallel... to control the commodity graphics accelerators and to perform oper- ations associated with a parallel... A Scalable and...

  19. Instruction sets for Parallel Random Access Machines. Doctoral thesis

    SciTech Connect (OSTI)

    Trahan, J.L.

    1988-08-01T23:59:59.000Z

    An important model of parallel computation is the Parallel Random Access Machine (PRAM), which comprises multiple processors that execute instructions synchronously and share a common memory. Formalized by Fortune and Wyllie (1978) and Goldschlager (1982), the PRAM is a much more natural model of parallel computation than older models such as combinational circuits and alternating Turing machines (Ruzzo, 1981) because the PRAM abstracts the salient features of a modern multiprocessor computer. Eventually an algorithm developed for the PRAM can be implemented on a parallel network computer such as a mesh-connected array computer (Thompson and Kung, 1977), a hypercube machine (Seitz, 1985), a cube-connected cycles machine (Preparata and Vuillemin, 1981) or a bounded degree processor network (Alt et al., 1987); on all network computers the routing of data complicates the implementation of algorithms. The PRAM provides the foundation for the design of highly parallel algorithms (Luby, 1986; Miller and Reif, 1985; among many others). This model permits the exposure of the intrinsic parallelism in a computational problem because it simplifies the communication of data through a shared memory. To quantify differences in computational performance, the time complexities of simulations between PRAMS with different instruction sets are determined. Focus is on the computational complexity of simulations between PRAMs with the following operations: multiplication, division, arbitrary left shift, arbitrary right shift, and probabilistic choice.

  20. Fast parallel algorithms for short-range molecular dynamics

    SciTech Connect (OSTI)

    Plimpton, S.

    1993-05-01T23:59:59.000Z

    Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a subset of atoms; the second assigns each a subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently -- those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 10,000,000 atoms on three parallel supercomputers, the nCUBE 2, Intel iPSC/860, and Intel Delta. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and the Intel Delta performs about 30 times faster than a single Y-MP processor and 12 times faster than a single C90 processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

  1. The role of low-mass star clusters in massive star formation in Orion

    E-Print Network [OSTI]

    Rivilla, V M; Jimenez-Serra, I; Rodriguez-Franco, A

    2013-01-01T23:59:59.000Z

    To distinguish between the different theories proposed to explain massive star formation, it is crucial to establish the distribution, the extinction, and the density of low-mass stars in massive star-forming regions. We analyzed deep X-ray observations of the Orion massive star-forming region using the Chandra Orion Ultradeep Project (COUP) catalog. We found that pre-main sequence (PMS) low-mass stars cluster toward the three massive star-forming regions: the Trapezium Cluster (TC), the Orion Hot Core (OHC), and OMC1-S. We derived low-mass stellar densities of 10^{5} stars pc^{-3} in the TC and OMC1-S, and of 10^{6} stars pc^{-3} in the OHC. The close association between the low-mass star clusters with massive star cradles supports the role of these clusters in the formation of massive stars. The X-ray observations show for the first time in the TC that low-mass stars with intermediate extinction are clustered toward the position of the most massive star, which is surrounded by a ring of non-extincted low-ma...

  2. Vacuum energy density and pressure of a massive scalar field

    E-Print Network [OSTI]

    Fernando Daniel Mera; S. A. Fulling

    2015-04-03T23:59:59.000Z

    With a view toward application of the Pauli-Villars regularization method to the Casimir energy of boundaries, we calculate the expectation values of the components of the stress tensor of a confined massive field in 1+1 space-time dimensions. Previous papers by Hays and Fulling are bridged and generalized. The Green function for the time-independent Schrodinger equation is constructed from the Green function for the whole line by the method of images; equivalently, the one-dimensional system is solved exactly in terms of closed classical paths and periodic orbits. Terms in the energy density and in the eigenvalue density attributable to the two boundaries individually and those attributable to the confinement of the field to a finite interval are distinguished so that their physical origins are clear. Then the pressure is found similarly from the cylinder kernel, the Green function associated most directly with an exponential frequency cutoff of the Fourier mode expansion. Finally, we discuss how the theory could be rendered finite by the Pauli-Villars method.

  3. Hawking-Moss instanton in nonlinear massive gravity

    SciTech Connect (OSTI)

    Zhang, Ying-li; Saito, Ryo; Sasaki, Misao, E-mail: yingli@yukawa.kyoto-u.ac.jp, E-mail: rsaito@yukawa.kyoto-u.ac.jp, E-mail: misao@yukawa.kyoto-u.ac.jp [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan)

    2013-02-01T23:59:59.000Z

    As a first step toward understanding a lanscape of vacua in a theory of non-linear massive gravity, we consider a landscape of a single scalar field and study tunneling between a pair of adjacent vacua. We study the Hawking-Moss (HM) instanton that sits at a local maximum of the potential, and evaluate the dependence of the tunneling rate on the parameters of the theory. It is found that provided with the same physical HM Hubble parameter H{sub HM}, depending on the values of parameters ?{sub 3} and ?{sub 4} in the action (2.2), the corresponding tunneling rate can be either enhanced or suppressed when compared to the one in the context of General Relativity (GR). Furthermore, we find the constraint on the ratio of the physical Hubble parameter to the fiducial one, which constrains the form of potential. This result is in sharp contrast to GR where there is no bound on the minimum value of the potential.

  4. Influence of massive planet scattering on nascent terrestrial planets

    E-Print Network [OSTI]

    Dimitri Veras; Philip J. Armitage

    2005-01-17T23:59:59.000Z

    In most extrasolar planetary systems, the present orbits of known giant planets admit the existence of stable terrestrial planets. Those same giant planets, however, have typically eccentric orbits that hint at violent early dynamics less benign for low mass planet formation. Under the assumption that massive planet eccentricities are the end point of gravitational scattering in multiple planet systems, we study the evolution of the building blocks of terrestrial planets during the scattering process. We find that typically, evolutionary sequences that result in a moderately eccentric giant planet orbiting at a ~ 2.5 AU eject over 95% of the material initially present within the habitable zone. Crossing orbits largely trigger the ejection, and leave the surviving material with a wide dispersion in semi-major axis, eccentricity and inclination. Based on these results, we predict that radial velocity follow-up of terrestrial planet systems found by Kepler will find that these are anti-correlated with the presence of eccentric giant planets orbiting at a few AU.

  5. Herschel Hi-GAL imaging of massive young stellar objects

    E-Print Network [OSTI]

    Olguin, F A; Wheelwright, H E; Clay, S J; de Wit, W -J; Rafiq, I; Pezzuto, S; Molinari, S

    2015-01-01T23:59:59.000Z

    We used Herschel Hi-GAL survey data to determine whether massive young stellar objects (MYSOs) are resolved at 70$\\mu$m and to study their envelope density distribution. Our analysis of three relatively isolated sources in the l=30{\\deg} and l=59{\\deg} Galactic fields show that the objects are partially resolved at 70$\\mu$m. The Herschel Hi-GAL survey data have a high scan velocity which makes unresolved and partially resolved sources appear elongated in the 70$\\mu$m images. We analysed the two scan directions separately and examine the intensity profile perpendicular to the scan direction. Spherically symmetric radiative transfer models with a power law density distribution were used to study the circumstellar matter distribution. Single dish sub-mm data were also included to study how different spatial information affects the fitted density distribution. The density distribution which best fits both the 70$\\mu$m intensity profile and SED has an average index of ~0.5. This index is shallower than expected an...

  6. Observational constraints on growth of massive black holes

    E-Print Network [OSTI]

    Qingjuan Yu; Scott Tremaine

    2002-05-16T23:59:59.000Z

    We study the observational constraints on the growth of massive black holes (BHs) in galactic nuclei. We use the velocity dispersions of early-type galaxies obtained by the SDSS and the relation between BH mass and velocity dispersion to estimate the local BH mass density to be 2.5x10^5 Msun/Mpc^3. We also use the QSO luminosity function from the 2dF Redshift Survey to estimate the BH mass density accreted during optically bright QSO phases. The local BH mass density is consistent with the density accreted during optically bright QSO phases if QSOs have an efficiency 0.1. By studying the continuity equation for the BH mass distribution, including the effect of BH mergers, we find relations between the local BH mass function and the QSO luminosity function. If the BH mass is assumed to be conserved during BH mergers, comparison of the predicted relations with the observations suggests that luminous QSOs (L_{bol}>10^{46} erg/s) have a high efficiency (e.g. 0.2), and the growth of high-mass BHs (>10^8 Msun) comes mainly from accretion during optically bright QSO phases, or that luminous QSOs have a super-Eddington luminosity. If luminous QSOs are not accreting with super-Eddington luminosities and the growth of low-mass BHs also occurs mainly during optically bright QSO phases, less luminous QSOs must accrete with a low efficiency 0.1.

  7. Supersonic Line Broadening within Young and Massive Super Star Clusters

    E-Print Network [OSTI]

    Tenorio-Tagle, G; Silich, S; Munoz-Tunon, C; Palous, J

    2009-01-01T23:59:59.000Z

    The origin of supersonic infrared and radio recombination nebular lines often detected in young and massive superstar clusters are discussed. We suggest that these arise from a collection of repressurizing shocks (RSs), acting effectively to re-establish pressure balance within the cluster volume and from the cluster wind which leads to an even broader although much weaker component. The supersonic lines are here shown to occur in clusters that undergo a bimodal hydrodynamic solution (Tenorio-Tagle et al. 2007), that is within clusters that are above the threshold line in the mechanical luminosity or cluster mass vs the size of the cluster (Silich et al. 2004). The plethora of repressurizing shocks is due to frequent and recurrent thermal instabilities that take place within the matter reinserted by stellar winds and supernovae. We show that the maximum speed of the RSs and of the cluster wind, are both functions of the temperature reached at the stagnation radius. This temperature depends only on the cluster...

  8. Vacuum energy density and pressure of a massive scalar field

    E-Print Network [OSTI]

    Fernando Daniel Mera; S. A. Fulling

    2015-02-15T23:59:59.000Z

    With a view toward application of the Pauli-Villars regularization method to the Casimir energy of boundaries, we calculate the expectation values of the components of the stress tensor of a confined massive field in 1+1 space-time dimensions. Previous papers by Hays and Fulling are bridged and generalized. The Green function for the time-independent Schrodinger equation is constructed from the Green function for the whole line by the method of images; equivalently, the one-dimensional system is solved exactly in terms of closed classical paths and periodic orbits. Terms in the energy density and in the eigenvalue density attributable to the two boundaries individually and those attributable to the confinement of the field to a finite interval are distinguished so that their physical origins are clear. Then the pressure is found similarly from the cylinder kernel, the Green function associated most directly with an exponential frequency cutoff of the Fourier mode expansion. Finally, we discuss how the theory could be rendered finite by the Pauli-Villars method.

  9. MASSCLEAN - MASSive CLuster Evolution and ANalysis Package - Description and Tests

    E-Print Network [OSTI]

    Bogdan Popescu; M. M. Hanson

    2009-05-28T23:59:59.000Z

    We present MASSCLEAN, a new, sophisticated and robust stellar cluster image and photometry simulation package. This visualization tool is able to create color-magnitude diagrams and standard FITS images in any of the traditional optical and near-infrared bands based on cluster characteristics input by the user, including but not limited to distance, age, mass, radius and extinction. At the limit of very distant, unresolved clusters, we have checked the integrated colors created in MASSCLEAN against those from other simple stellar population models with consistent results. We have also tested models which provide a reasonable estimate of the field star contamination in images and color-magnitude diagrams. We demonstrate the package by simulating images and color-magnitude diagrams of well known massive Milky Way clusters and compare their appearance to real data. Because the algorithm populates the cluster with a discrete number of tenable stars, it can be used as part of a Monte Carlo Method to derive the pr obabilistic range of characteristics (integrated colors, for example) consistent with a given cluster mass and age. Our simulation package is available for download and will run on any standard desktop running UNIX/Linux. Full documentation on installation and its use is also available. Finally, a web-based version of MASSCLEAN which can be immediately used and is sufficiently adaptable for most applications is available through a web interface.

  10. Vacuum energy density and pressure of a massive scalar field

    E-Print Network [OSTI]

    Fernando Daniel Mera; S. A. Fulling

    2014-12-29T23:59:59.000Z

    With a view toward application of the Pauli-Villars regularization method to the Casimir energy of boundaries, we calculate the expectation values of the components of the stress tensor of a confined massive field in 1+1 space-time dimensions. Previous papers by Hays and Fulling are bridged and generalized. The Green function for the time-independent Schrodinger equation is constructed from the Green function for the whole line by the method of images; equivalently, the one-dimensional system is solved exactly in terms of closed classical paths and periodic orbits. Terms in the energy density and in the eigenvalue density attributable to the two boundaries individually and those attributable to the confinement of the field to a finite interval are distinguished so that their physical origins are clear. Then the pressure is found similarly from the cylinder kernel, the Green function associated most directly with an exponential frequency cutoff of the Fourier mode expansion. Finally, we discuss how the theory could be rendered finite by the Pauli-Villars method.

  11. GIS Applications in MeteorologyGIS Applications in Meteorology Adventures in a Parallel UniverseAdventures in a Parallel Universe

    E-Print Network [OSTI]

    Expanding HorizonsExpanding Horizons Ted Haberman ­ What is GIS? Shipley - Parallel (GIS) Universe Olga from GIS COTS software. TheGIS COTS software. The purpose of the forum is to explore the ways in which

  12. Outflow Feedback Regulated Massive Star Formation in Parsec-Scale Cluster Forming Clumps

    SciTech Connect (OSTI)

    Wang, Peng; /KIPAC, Menlo Park /Stanford U., Phys.Dept.; Li, Zhi-Yun; /Virginia U., Astron. Dept.; Abel, Tom; /KIPAC, Menlo Park /Stanford U., Phys.Dept.; Nakamura, Fumitaka; /Niigata U.

    2010-02-15T23:59:59.000Z

    We investigate massive star formation in turbulent, magnetized, parsec-scale clumps of molecular clouds including protostellar outflow feedback using three dimensional numerical simulations of effective resolution 2048{sup 3}. The calculations are carried out using a block structured adaptive mesh refinement code that solves the ideal MHD equations including self-gravity and implements accreting sink particles. We find that, in the absence of regulation by magnetic fields and outflow feedback, massive stars form readily in a turbulent, moderately condensed clump of {approx} 1,600 M{sub {circle_dot}} (containing {approx} 10{sup 2} initial Jeans masses), along with a cluster of hundreds of lower mass stars. The massive stars are fed at high rates by (1) transient dense filaments produced by large-scale turbulent compression at early times, and (2) by the clump-wide global collapse resulting from turbulence decay at late times. In both cases, the bulk of the massive star's mass is supplied from outside a 0.1 pc-sized 'core' that surrounds the star. In our simulation, the massive star is clump-fed rather than core-fed. The need for large-scale feeding makes the massive star formation prone to regulation by outflow feedback, which directly opposes the feeding processes. The outflows reduce the mass accretion rates onto the massive stars by breaking up the dense filaments that feed the massive star formation at early times, and by collectively slowing down the global collapse that fuel the massive star formation at late times. The latter is aided by a moderate magnetic field of strength in the observed range (corresponding to a dimensionless clump mass-to-flux ratio {lambda} {approx} a few); the field allows the outflow momenta to be deposited more efficiently inside the clump. We conclude that the massive star formation in our simulated turbulent, magnetized, parsec-scale clump is outflow-regulated and clump-fed (ORCF for short). An important implication is that the formation of low-mass stars in a dense clump can affect the formation of massive stars in the same clump, through their outflow feedback on the clump dynamics. In a companion paper, we discuss the properties of the lower mass cluster members formed along with the massive stars, including their mass distribution and spatial clustering.

  13. Magnetic Monopoles and Massive Photons in a Weyl-Type Electrodynamics

    E-Print Network [OSTI]

    Mark Israelit

    1996-11-25T23:59:59.000Z

    In a previous work the Weyl-Dirac framework was generalized in order to obtain a geometrically based general relativistic theory, possessing intrinsic electric and magnetic currents and admitting massive photons. Some physical phenomena in that framework are considered. So it is shown that massive photons may exist only in presence of an intrinsic magnetic field. The role of massive photons is essential in order to get an interaction between magnetic currents. A static spherically symmetric solution is obtained. It may lead either to the Reissner-Nordstr{\\o}m metric, or to the metric created by a magnetic monopole.

  14. A faint galaxy redshift survey behind massive clusters

    SciTech Connect (OSTI)

    Frye, Brenda

    1999-12-01T23:59:59.000Z

    This thesis is concerned with the gravitational lensing effect by massive galaxy clusters. We have explored a new technique for measuring galaxy masses and for detecting high-z galaxies by their optical colors. A redshift survey has been obtained at the Keck for a magnitude limited sample of objects (I<23) behind three clusters, A1689, A2390, and A2218 within a radius of 0.5M pc. For each cluster we see both a clear trend of increasing flux and redshift towards the center. This behavior is the result of image magnifications, such that at fixed redshift one sees further down the luminosity function. The gradient of this magnification is, unlike measurements of image distortion, sensitive to the mass profile, and found to depart strongly from a pure isothermal halo. We have found that V RI color selection can be used effectively as a discriminant for finding high-z galaxies behind clusters and present five 4.1 < z < 5.1 spectra which are of very high quality due to their high mean magnification of {approximately}20, showing strong, visibly-saturated interstellar metal lines in some cases. We have also investigated the radio ring lens PKS 1830-211, locating the source and multiple images and detected molecular absorption at mm wavelengths. Broad molecular absorption of width 1/40kms is found toward the southwest component only, where surprisingly it does not reach the base of the continuum, which implies incomplete coverage of the SW component by molecular gas, despite the small projected size of the source, less than 1/8h pc at the absorption redshift.

  15. Evolution of Massive Protostars with High Accretion Rates

    E-Print Network [OSTI]

    Takashi Hosokawa; Kazuyuki Omukai

    2008-06-25T23:59:59.000Z

    Formation of massive stars by accretion requires a high accretion rate of > 10^-4 M_sun/yr to overcome the radiation pressure barrier of the forming stars. Here, we study evolution of protostars accreting at such high rates, by solving the structure of the central star and the inner accreting envelope simultaneously. The protostellar evolution is followed starting from small initial cores until their arrival at the stage of the Zero-Age Main Sequence (ZAMS) stars. An emphasis is put on evolutionary features different from those with a low accretion rate of 10^-5 M_sun/yr, which is presumed in the standard scenario for low-mass star formation. With the high accretion rate of 10^-3 M_sun/yr, the protostellar radius becomes very large and exceeds 100 R_sun. It is not until the stellar mass reaches 40 M_sun that hydrogen burning begins and the protostar reaches the ZAMS phase, and this ZAMS arrival mass increases with the accretion rate. At a very high accretion rate of > 3 x 10^-3 M_sun/yr, the total luminosity of the protostar becomes so high that the resultant radiation pressure inhibits the growth of the protostars under steady accretion before reaching the ZAMS stage. Therefore, the evolution under the critical accretion rate 3 x 10^-3 M_sun/yr gives the upper mass limit of possible pre-main-sequence stars at 60 M_sun. The upper mass limit of MS stars is also set by the radiation pressure onto the dusty envelope under the same accretion rate at 250 M_sun. We also propose that the central source enshrouded in the Orion KL/BN nebula has effective temperature and luminosity consistent with our model, and is a possible candidate for such protostars growing under the high accretion rate. (abridged)

  16. SELF-REGULATED SHOCKS IN MASSIVE STAR BINARY SYSTEMS

    SciTech Connect (OSTI)

    Parkin, E. R.; Sim, S. A., E-mail: parkin@mso.anu.edu.au, E-mail: s.sim@qub.ac.uk [Research School of Astronomy and Astrophysics, Australian National University, ACT 2611 (Australia)

    2013-04-20T23:59:59.000Z

    In an early-type, massive star binary system, X-ray bright shocks result from the powerful collision of stellar winds driven by radiation pressure on spectral line transitions. We examine the influence of the X-rays from the wind-wind collision shocks on the radiative driving of the stellar winds using steady-state models that include a parameterized line force with X-ray ionization dependence. Our primary result is that X-ray radiation from the shocks inhibits wind acceleration and can lead to a lower pre-shock velocity, and a correspondingly lower shocked plasma temperature, yet the intrinsic X-ray luminosity of the shocks, L{sub X}, remains largely unaltered, with the exception of a modest increase at small binary separations. Due to the feedback loop between the ionizing X-rays from the shocks and the wind driving, we term this scenario as self-regulated shocks. This effect is found to greatly increase the range of binary separations at which a wind-photosphere collision is likely to occur in systems where the momenta of the two winds are significantly different. Furthermore, the excessive levels of X-ray ionization close to the shocks completely suppress the line force, and we suggest that this may render radiative braking less effective. Comparisons of model results against observations reveal reasonable agreement in terms of log (L{sub X}/L{sub bol}). The inclusion of self-regulated shocks improves the match for kT values in roughly equal wind momenta systems, but there is a systematic offset for systems with unequal wind momenta (if considered to be a wind-photosphere collision).

  17. The Challenges of Massive On-chip Concurrency Kostas Bousias and Chris Jesshope

    E-Print Network [OSTI]

    Jesshope, Chris

    . Chip-level mul- tiprocessors exploiting massive concurrency we term Microgrids. The direc- tions Microgrids. Microgrids will also form the basis of mega-scale computing systems, comprising millions

  18. Effects of a new 3-alpha reaction on the s-process in massive stars

    SciTech Connect (OSTI)

    Kikuch, Yukihiro; Ono, Masaomi; Matsuo, Yasuhide; Hashimoto, Masa-aki; Fujimoto, Shin-ichiro [Department of physics, Kyushu University, Fukuoka 812-8581 (Japan); Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan); Department of physics, Kyushu University, Fukuoka 812-8581 (Japan); Kumamoto National College of Technology, Kumamoto 861-1102 (Japan)

    2012-11-12T23:59:59.000Z

    Effect of a new 3-alpha reaction rate on the s-process during the evolution of a massive star of 25 solar mass is investigated for the first time, because the s-process in massive stars have been believed to be established with only minor change. We find that the s-process with use of the new rate during the core helium burning is very inefficient compared to the case with the previous 3-alpha rate. However, the difference of the overproduction is found to be largely compensated by the subsequent carbon burning. Since the s-process in massive stars has been attributed so far to the neutron irradiation during core helium burning, our finding reveals for the first time the importance of the carbon burning for the s-process during the evolution of massive stars.

  19. Ecology and evolution simulation and quest design for an educational massive multiplayer online game

    E-Print Network [OSTI]

    Zhang, Mark (Mark A.)

    2013-01-01T23:59:59.000Z

    In this design-based research project, I developed two simulations to be used as student tools in a massively multiplayer online game targeted at STEM education, the Radix Endeavor. I designed both the underlying agent-based ...

  20. THE RED MSX SOURCE SURVEY: THE MASSIVE YOUNG STELLAR POPULATION OF OUR GALAXY

    SciTech Connect (OSTI)

    Lumsden, S. L.; Hoare, M. G.; Oudmaijer, R. D.; Cooper, H. D. B. [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Urquhart, J. S. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, Bonn (Germany); Davies, B.; Moore, T. J. T. [Astrophysics Research Institute, Liverpool John Moores University, Liverpool L3 5RF (United Kingdom); Mottram, J. C. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)

    2013-09-01T23:59:59.000Z

    We present the Red MSX Source survey, the largest statistically selected catalog of young massive protostars and H II regions to date. We outline the construction of the catalog using mid- and near-infrared color selection. We also discuss the detailed follow up work at other wavelengths, including higher spatial resolution data in the infrared. We show that within the adopted selection bounds we are more than 90% complete for the massive protostellar population, with a positional accuracy of the exciting source of better than 2 arcsec. We briefly summarize some of the results that can be obtained from studying the properties of the objects in the catalog as a whole; we find evidence that the most massive stars form: (1) preferentially nearer the Galactic center than the anti-center; (2) in the most heavily reddened environments, suggestive of high accretion rates; and (3) from the most massive cloud cores.

  1. Transformations in Massive Binary Stars: CRA Colloquium, Jan. 15, 2009 1 Mass and Angular Momentum

    E-Print Network [OSTI]

    Gies, Douglas R.

    over lives Progenitors of the Long Gamma Ray Bursts Binary Star Surveys Early Stages of Interacting, 2009 3 Progenitors of Long Gamma Ray Bursts Collapsar model (Woosley 1993): core of a massive, fast

  2. Parallel Breadth-First Search on Distributed Memory Systems

    SciTech Connect (OSTI)

    Computational Research Division; Buluc, Aydin; Madduri, Kamesh

    2011-04-15T23:59:59.000Z

    Data-intensive, graph-based computations are pervasive in several scientific applications, and are known to to be quite challenging to implement on distributed memory systems. In this work, we explore the design space of parallel algorithms for Breadth-First Search (BFS), a key subroutine in several graph algorithms. We present two highly-tuned par- allel approaches for BFS on large parallel systems: a level-synchronous strategy that relies on a simple vertex-based partitioning of the graph, and a two-dimensional sparse matrix- partitioning-based approach that mitigates parallel commu- nication overhead. For both approaches, we also present hybrid versions with intra-node multithreading. Our novel hybrid two-dimensional algorithm reduces communication times by up to a factor of 3.5, relative to a common vertex based approach. Our experimental study identifies execu- tion regimes in which these approaches will be competitive, and we demonstrate extremely high performance on lead- ing distributed-memory parallel systems. For instance, for a 40,000-core parallel execution on Hopper, an AMD Magny- Cours based system, we achieve a BFS performance rate of 17.8 billion edge visits per second on an undirected graph of 4.3 billion vertices and 68.7 billion edges with skewed degree distribution.

  3. Distance-Two Interpolation for Parallel Algebraic Multigrid

    SciTech Connect (OSTI)

    De Sterck, H; Falgout, R; Nolting, J; Yang, U M

    2007-05-08T23:59:59.000Z

    Algebraic multigrid (AMG) is one of the most efficient and scalable parallel algorithms for solving sparse linear systems on unstructured grids. However, for large three-dimensional problems, the coarse grids that are normally used in AMG often lead to growing complexity in terms of memory use and execution time per AMG V-cycle. Sparser coarse grids, such as those obtained by the Parallel Modified Independent Set coarsening algorithm (PMIS) [7], remedy this complexity growth, but lead to non-scalable AMG convergence factors when traditional distance-one interpolation methods are used. In this paper we study the scalability of AMG methods that combine PMIS coarse grids with long distance interpolation methods. AMG performance and scalability is compared for previously introduced interpolation methods as well as new variants of them for a variety of relevant test problems on parallel computers. It is shown that the increased interpolation accuracy largely restores the scalability of AMG convergence factors for PMIS-coarsened grids, and in combination with complexity reducing methods, such as interpolation truncation, one obtains a class of parallel AMG methods that enjoy excellent scalability properties on large parallel computers.

  4. Parallel heat transport in integrable and chaotic magnetic fields

    SciTech Connect (OSTI)

    Castillo-Negrete, D. del; Chacon, L. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States)

    2012-05-15T23:59:59.000Z

    The study of transport in magnetized plasmas is a problem of fundamental interest in controlled fusion, space plasmas, and astrophysics research. Three issues make this problem particularly challenging: (i) The extreme anisotropy between the parallel (i.e., along the magnetic field), {chi}{sub ||} , and the perpendicular, {chi}{sub Up-Tack }, conductivities ({chi}{sub ||} /{chi}{sub Up-Tack} may exceed 10{sup 10} in fusion plasmas); (ii) Nonlocal parallel transport in the limit of small collisionality; and (iii) Magnetic field lines chaos which in general complicates (and may preclude) the construction of magnetic field line coordinates. Motivated by these issues, we present a Lagrangian Green's function method to solve the local and non-local parallel transport equation applicable to integrable and chaotic magnetic fields in arbitrary geometry. The method avoids by construction the numerical pollution issues of grid-based algorithms. The potential of the approach is demonstrated with nontrivial applications to integrable (magnetic island), weakly chaotic (Devil's staircase), and fully chaotic magnetic field configurations. For the latter, numerical solutions of the parallel heat transport equation show that the effective radial transport, with local and non-local parallel closures, is non-diffusive, thus casting doubts on the applicability of quasilinear diffusion descriptions. General conditions for the existence of non-diffusive, multivalued flux-gradient relations in the temperature evolution are derived.

  5. Parallel MATLAB at VT Gene Cliff (AOE/ICAM -ecliff@vt.edu )

    E-Print Network [OSTI]

    Crawford, T. Daniel

    Parallel MATLAB at VT Gene Cliff (AOE/ICAM - ecliff@vt.edu ) Justin Krometis (ARC/ICAM - jkrometis Mathematics 1 / 35 #12;MATLAB Parallel Computing Introduction Programming Models Execution Example: Quadrature Conclusion 2 / 35 #12;INTRO: Parallel MATLAB Parallel MATLAB is an extension of MATLAB that takes advantage

  6. Fasteners -- Preloading test for the detection of hydrogen embrittlement -- Parallel bearing surface method

    E-Print Network [OSTI]

    International Organization for Standardization. Geneva

    1999-01-01T23:59:59.000Z

    Fasteners -- Preloading test for the detection of hydrogen embrittlement -- Parallel bearing surface method

  7. A Design Pattern Language for Engineering (Parallel) Kurt Keutzer (EECS UC Berkeley) and Tim Mattson (Intel)

    E-Print Network [OSTI]

    , in the one community with a long tradition of parallel computing (high performance computing) the old

  8. Evaluation of massive hydraulic fracturing experiments in the Devonian Shales in Lincoln County, West Virginia

    E-Print Network [OSTI]

    Holgate, Karen Elaine

    1987-01-01T23:59:59.000Z

    EVALUATION OF MASSIVE HYDRAULIC FRACTURING EXPERIMENTS IN THE DEVONIAN SHALES IN LINCOLN COUNTY, WEST VIRGINIA A Thesis by KAREN ELAINE HOLGATE Submitted to the Graduate College of Texas ALM University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE May 1987 Major Subject: Petroleum Engineering EVALUATION OF MASSIVE HYDRAULIC FRACTURING EXPERIMENTS IN THE DEVONIAN SHALES IN LINCOLN COUNTY, WEST VIRGINIA A Thesis by KAREN ELAINE HDLGATE Approved...

  9. Decay of Dirac Massive Hair in the Background of Spherical Black Hole

    E-Print Network [OSTI]

    Rafa? Moderski; Marek Rogatko

    2008-05-06T23:59:59.000Z

    The intermediate and late-time behaviour of massive Dirac hair in the static spherically symmetric black hole spacetime was studied. It was revealed that the intermediate asymptotic pattern of decay of massive Dirac spinor hair is dependent on the mass of the field under consideration as well as the multiple number of the wave mode. The long-lived oscillatory tail observed at timelike infinity in the considered background decays slowly as t^{-5/6}.

  10. Massive-scale RDF Processing Using Compressed Bitmap Indexes

    SciTech Connect (OSTI)

    Madduri, Kamesh; Wu, Kesheng

    2011-05-26T23:59:59.000Z

    The Resource Description Framework (RDF) is a popular data model for representing linked data sets arising from the web, as well as large scienti#12;c data repositories such as UniProt. RDF data intrinsically represents a labeled and directed multi-graph. SPARQL is a query language for RDF that expresses subgraph pattern-#12;nding queries on this implicit multigraph in a SQL- like syntax. SPARQL queries generate complex intermediate join queries; to compute these joins e#14;ciently, we propose a new strategy based on bitmap indexes. We store the RDF data in column-oriented structures as compressed bitmaps along with two dictionaries. This paper makes three new contributions. (i) We present an e#14;cient parallel strategy for parsing the raw RDF data, building dictionaries of unique entities, and creating compressed bitmap indexes of the data. (ii) We utilize the constructed bitmap indexes to e#14;ciently answer SPARQL queries, simplifying the join evaluations. (iii) To quantify the performance impact of using bitmap indexes, we compare our approach to the state-of-the-art triple-store RDF-3X. We #12;nd that our bitmap index-based approach to answering queries is up to an order of magnitude faster for a variety of SPARQL queries, on gigascale RDF data sets.

  11. The role of low-mass star clusters in massive star formation. The Orion Case

    E-Print Network [OSTI]

    Rivilla, V M; Jimenez-Serra, I; Rodriguez-Franco, A

    2013-01-01T23:59:59.000Z

    To distinguish between the different theories proposed to explain massive star formation, it is crucial to establish the distribution, the extinction, and the density of low-mass stars in massive star-forming regions. We analyze deep X-ray observations of the Orion massive star-forming region using the Chandra Orion Ultradeep Project (COUP) catalog. We studied the stellar distribution as a function of extinction, with cells of 0.03 pc x 0.03 pc, the typical size of protostellar cores. We derived stellar density maps and calculated cluster stellar densities. We found that low-mass stars cluster toward the three massive star-forming regions: the Trapezium Cluster (TC), the Orion Hot Core (OHC), and OMC1-S. We derived low-mass stellar densities of 10^{5} stars pc^{-3} in the TC and OMC1-S, and of 10^{6} stars pc^{-3} in the OHC. The close association between the low-mass star clusters with massive star cradles supports the role of these clusters in the formation of massive stars. The X-ray observations show for ...

  12. Synchronous parallel kinetic Monte Carlo Diffusion in Heterogeneous Systems

    SciTech Connect (OSTI)

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

    2010-12-06T23:59:59.000Z

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

  13. Performance analysis of parallel supernodal sparse LU factorization

    SciTech Connect (OSTI)

    Grigori, Laura; Li, Xiaoye S.

    2004-02-05T23:59:59.000Z

    We investigate performance characteristics for the LU factorization of large matrices with various sparsity patterns. We consider supernodal right-looking parallel factorization on a bi-dimensional grid of processors, making use of static pivoting. We develop a performance model and we validate it using the implementation in SuperLU-DIST, the real matrices and the IBM Power3 machine at NERSC. We use this model to obtain performance bounds on parallel computers, to perform scalability analysis and to identify performance bottlenecks. We also discuss the role of load balance and data distribution in this approach.

  14. Local and nonlocal parallel heat transport in general magnetic fields

    SciTech Connect (OSTI)

    Del-Castillo-Negrete, Diego B [ORNL; Chacon, Luis [ORNL

    2011-01-01T23:59:59.000Z

    A novel approach for the study of parallel transport in magnetized plasmas is presented. The method avoids numerical pollution issues of grid-based formulations and applies to integrable and chaotic magnetic fields with local or nonlocal parallel closures. In weakly chaotic fields, the method gives the fractal structure of the devil's staircase radial temperature profile. In fully chaotic fields, the temperature exhibits self-similar spatiotemporal evolution with a stretched-exponential scaling function for local closures and an algebraically decaying one for nonlocal closures. It is shown that, for both closures, the effective radial heat transport is incompatible with the quasilinear diffusion model.

  15. Local and Nonlocal Parallel Heat Transport in General Magnetic Fields

    SciTech Connect (OSTI)

    Castillo-Negrete, D. del; Chacon, L. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States)

    2011-05-13T23:59:59.000Z

    A novel approach for the study of parallel transport in magnetized plasmas is presented. The method avoids numerical pollution issues of grid-based formulations and applies to integrable and chaotic magnetic fields with local or nonlocal parallel closures. In weakly chaotic fields, the method gives the fractal structure of the devil's staircase radial temperature profile. In fully chaotic fields, the temperature exhibits self-similar spatiotemporal evolution with a stretched-exponential scaling function for local closures and an algebraically decaying one for nonlocal closures. It is shown that, for both closures, the effective radial heat transport is incompatible with the quasilinear diffusion model.

  16. Global synchronization of parallel processors using clock pulse width modulation

    DOE Patents [OSTI]

    Chen, Dong; Ellavsky, Matthew R.; Franke, Ross L.; Gara, Alan; Gooding, Thomas M.; Haring, Rudolf A.; Jeanson, Mark J.; Kopcsay, Gerard V.; Liebsch, Thomas A.; Littrell, Daniel; Ohmacht, Martin; Reed, Don D.; Schenck, Brandon E.; Swetz, Richard A.

    2013-04-02T23:59:59.000Z

    A circuit generates a global clock signal with a pulse width modification to synchronize processors in a parallel computing system. The circuit may include a hardware module and a clock splitter. The hardware module may generate a clock signal and performs a pulse width modification on the clock signal. The pulse width modification changes a pulse width within a clock period in the clock signal. The clock splitter may distribute the pulse width modified clock signal to a plurality of processors in the parallel computing system.

  17. Methods for operating parallel computing systems employing sequenced communications

    DOE Patents [OSTI]

    Benner, R.E.; Gustafson, J.L.; Montry, G.R.

    1999-08-10T23:59:59.000Z

    A parallel computing system and method are disclosed having improved performance where a program is concurrently run on a plurality of nodes for reducing total processing time, each node having a processor, a memory, and a predetermined number of communication channels connected to the node and independently connected directly to other nodes. The present invention improves performance of the parallel computing system by providing a system which can provide efficient communication between the processors and between the system and input and output devices. A method is also disclosed which can locate defective nodes with the computing system. 15 figs.

  18. Small file aggregation in a parallel computing system

    DOE Patents [OSTI]

    Faibish, Sorin; Bent, John M.; Tzelnic, Percy; Grider, Gary; Zhang, Jingwang

    2014-09-02T23:59:59.000Z

    Techniques are provided for small file aggregation in a parallel computing system. An exemplary method for storing a plurality of files generated by a plurality of processes in a parallel computing system comprises aggregating the plurality of files into a single aggregated file; and generating metadata for the single aggregated file. The metadata comprises an offset and a length of each of the plurality of files in the single aggregated file. The metadata can be used to unpack one or more of the files from the single aggregated file.

  19. Intelligent energy management agent for a parallel hybrid vehicle

    E-Print Network [OSTI]

    Won, Jong-Seob

    2004-09-30T23:59:59.000Z

    INTELLIGENT ENERGY MANAGEMENT AGENT FOR A PARALLEL HYBRID VEHICLE A Dissertation by JONG-SEOB WON Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment of the requirements for the degree of DOCTOR OF PHILOSOPHY May... 2003 Major Subject: Mechanical Engineering INTELLIGENT ENERGY MANAGEMENT AGENT FOR A PARALLEL HYBRID VEHICLE A Dissertation by JONG-SEOB WON Submitted to Texas A&M University in partial ful llment of the requirements for the degree of DOCTOR...

  20. Building a Parallel Cloud Storage System using OpenStack’s Swift Object Store and Transformative Parallel I/O

    SciTech Connect (OSTI)

    Burns, Andrew J. [Los Alamos National Laboratory; Lora, Kaleb D. [Los Alamos National Laboratory; Martinez, Esteban [Los Alamos National Laboratory; Shorter, Martel L. [Los Alamos National Laboratory

    2012-07-30T23:59:59.000Z

    Our project consists of bleeding-edge research into replacing the traditional storage archives with a parallel, cloud-based storage solution. It used OpenStack's Swift Object Store cloud software. It's Benchmarked Swift for write speed and scalability. Our project is unique because Swift is typically used for reads and we are mostly concerned with write speeds. Cloud Storage is a viable archive solution because: (1) Container management for larger parallel archives might ease the migration workload; (2) Many tools that are written for cloud storage could be utilized for local archive; and (3) Current large cloud storage practices in industry could be utilized to manage a scalable archive solution.