Sample records for massively parallel microcell-based

  1. Massively parallel neural computation

    E-Print Network [OSTI]

    Fox, Paul James

    2013-03-12T23:59:59.000Z

    work and includes nothing which is the outcome of work done in collaboration except where specifically indicated in the text. This dissertation does not exceed the regulation length of 60 000 words, including tables and footnotes. Massively Parallel... -flow pipeline (Thomas and Luk, 2009; Cas- sidy et al., 2011; Martinez-Alvarez et al., 2007; Rice et al., 2009). Mathematical neuron models are amenable to being converted to pipelines with many stages (Rice et al. use 23 stages for an Izhikevich neuron model...

  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. Template based parallel checkpointing in a massively parallel computer system

    DOE Patents [OSTI]

    Archer, Charles Jens (Rochester, MN); Inglett, Todd Alan (Rochester, MN)

    2009-01-13T23:59:59.000Z

    A method and apparatus for a template based parallel checkpoint save for a massively parallel super computer system using a parallel variation of the rsync protocol, and network broadcast. In preferred embodiments, the checkpoint data for each node is compared to a template checkpoint file that resides in the storage and that was previously produced. Embodiments herein greatly decrease the amount of data that must be transmitted and stored for faster checkpointing and increased efficiency of the computer system. Embodiments are directed to a parallel computer system with nodes arranged in a cluster with a high speed interconnect that can perform broadcast communication. The checkpoint contains a set of actual small data blocks with their corresponding checksums from all nodes in the system. The data blocks may be compressed using conventional non-lossy data compression algorithms to further reduce the overall checkpoint size.

  4. MPMM: A Massively Parallel Mesoscale Model

    SciTech Connect (OSTI)

    Foster, I.; Michalakes, J.

    1992-12-31T23:59:59.000Z

    Static domain decomposition is a technique that provides a quick path to porting atmospheric models on distributed memory parallel computers. However, parallel inefficiencies in the form of load imbalances and ill-tuned communication are difficult to correct without complicated and explicit recoding. Reconfiguring the code to run on larger or smaller numbers of processors may require recompiling. Modularity and machine independence may also suffer. If full advantage is to be taken of Massively Parallel Processing (MPP) technology, tools and techniques that allow for dynamic performance tuning and reconfiguration are required. Program Composition Notation (PCN) is a language and run-time system for expressing parallel programs developed at Argonne and at the California Institute of Technology. It provides an intermediate layer between the application program and the physical processors of a computer. It allows the model to be statically decomposed over a virtual machine, but this virtual machine can be mapped and remapped dynamically over the physical computer. Programs are portable to as many machines as PCN itself, modularity is easily preserved, and communication tuning for a particular computer is encapsulated within the PCN run-time system. In this paper we report on a project at Argonne National Laboratory to parallelize the Penn State/NCAR Mesoscale Model version 5 using a fine grain decomposition dynamically mapped and managed under PCN.

  5. Shift: A Massively Parallel Monte Carlo Radiation Transport Package

    SciTech Connect (OSTI)

    Pandya, Tara M [ORNL; Johnson, Seth R [ORNL; Davidson, Gregory G [ORNL; Evans, Thomas M [ORNL; Hamilton, Steven P [ORNL

    2015-01-01T23:59:59.000Z

    This paper discusses the massively-parallel Monte Carlo radiation transport package, Shift, de- veloped at Oak Ridge National Laboratory. It reviews the capabilities, implementation, and parallel performance of this code package. Scaling results demonstrate very good strong and weak scaling behavior of the implemented algorithms. Benchmark results from various reactor problems show that Shift results compare well to other contemporary Monte Carlo codes and experimental results.

  6. 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.

  7. 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.

  8. 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.

  9. Scalable massively parallel simplex algorithms for block-structured linear programs

    E-Print Network [OSTI]

    Hall, Julian

    Scalable massively parallel simplex algorithms for block-structured linear programs Ilkay Boduro of Mathematics, University of Edinburgh September 14th 2007 Scalable massively parallel simplex algorithms for block-structured linear programs #12;Simplex methods for LP problems minimize f = cT x subject to Ax = b

  10. Stability Analysis of Large-Scale Incompressible Flow Calculations on Massively Parallel Computers 1 Stability Analysis of Large-

    E-Print Network [OSTI]

    Stability Analysis of Large-Scale Incompressible Flow Calculations on Massively Parallel Computers 1 Stability Analysis of Large- Scale Incompressible Flow Calculations on Massively Parallel disturbances aligned with the associated eigenvectors will grow. The Cayley transformation, cou- pled

  11. 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 ...

  12. 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 

  13. Scalable Parallel Algorithms for Massive Scale-free Graphs

    E-Print Network [OSTI]

    Pearce, Roger Allan

    2013-12-05T23:59:59.000Z

    , distributed, and external memory. This dissertation develops new techniques to parallelize the storage, computation, and communication for scale-free graphs with high-degree vertices. Our work facilitates the processing of large real-world graph datasets...

  14. Scalable Parallel Algorithms for Massive Scale-free Graphs 

    E-Print Network [OSTI]

    Pearce, Roger Allan

    2013-12-05T23:59:59.000Z

    , distributed, and external memory. This dissertation develops new techniques to parallelize the storage, computation, and communication for scale-free graphs with high-degree vertices. Our work facilitates the processing of large real-world graph datasets...

  15. 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...

  16. 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

  17. 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

  18. Massively Parallel Scanning Probe Nanolithography Daniel J. Arbuckle and Aristides A. G. Requicha

    E-Print Network [OSTI]

    Southern California, University of

    Massively Parallel Scanning Probe Nanolithography Daniel J. Arbuckle and Aristides A. G. Requicha on Scanning Probe Microscopy (SPM) are sequential, and therefore have a low throughput. This paper discusses are presented to validate the approach. Keywords-Nanorobotics, Scanning Probe Microscopy (SPM), Multi-Tip SPM

  19. Massively parallel implementation of the Penn State/NCAR Mesoscale Model

    SciTech Connect (OSTI)

    Foster, I.; Michalakes, J.

    1992-12-01T23:59:59.000Z

    Parallel computing promises significant improvements in both the raw speed and cost performance of mesoscale atmospheric models. On distributed-memory massively parallel computers available today, the performance of a mesoscale model will exceed that of conventional supercomputers; on the teraflops machines expected within the next five years, performance will increase by several orders of magnitude. As a result, scientists will be able to consider larger problems, more complex model processes, and finer resolutions. In this paper. we report on a project at Argonne National Laboratory that will allow scientists to take advantage of parallel computing technology. This Massively Parallel Mesoscale Model (MPMM) will be functionally equivalent to the Penn State/NCAR Mesoscale Model (MM). In a prototype study, we produced a parallel version of MM4 using a static (compile-time) coarse-grained ``patch`` decomposition. This code achieves one-third the performance of a one-processor CRAY Y-MP on twelve Intel 1860 microprocessors. The current version of MPMM is based on all MM5 and uses a more fine-grained approach, decomposing the grid as finely as the mesh itself allows so that each horizontal grid cell is a parallel process. This will allow the code to utilize many hundreds of processors. A high-level language for expressing parallel programs is used to implement communication strearns between the processes in a way that permits dynamic remapping to the physical processors of a particular parallel computer. This facilitates load balancing, grid nesting, and coupling with graphical systems and other models.

  20. Massively parallel implementation of the Penn State/NCAR Mesoscale Model

    SciTech Connect (OSTI)

    Foster, I.; Michalakes, J.

    1992-01-01T23:59:59.000Z

    Parallel computing promises significant improvements in both the raw speed and cost performance of mesoscale atmospheric models. On distributed-memory massively parallel computers available today, the performance of a mesoscale model will exceed that of conventional supercomputers; on the teraflops machines expected within the next five years, performance will increase by several orders of magnitude. As a result, scientists will be able to consider larger problems, more complex model processes, and finer resolutions. In this paper. we report on a project at Argonne National Laboratory that will allow scientists to take advantage of parallel computing technology. This Massively Parallel Mesoscale Model (MPMM) will be functionally equivalent to the Penn State/NCAR Mesoscale Model (MM). In a prototype study, we produced a parallel version of MM4 using a static (compile-time) coarse-grained patch'' decomposition. This code achieves one-third the performance of a one-processor CRAY Y-MP on twelve Intel 1860 microprocessors. The current version of MPMM is based on all MM5 and uses a more fine-grained approach, decomposing the grid as finely as the mesh itself allows so that each horizontal grid cell is a parallel process. This will allow the code to utilize many hundreds of processors. A high-level language for expressing parallel programs is used to implement communication strearns between the processes in a way that permits dynamic remapping to the physical processors of a particular parallel computer. This facilitates load balancing, grid nesting, and coupling with graphical systems and other models.

  1. Salinas - An implicit finite element structural dynamics code developed for massively parallel platforms

    SciTech Connect (OSTI)

    BHARDWAJ, MANLJ K.; REESE,GARTH M.; DRIESSEN,BRIAN; ALVIN,KENNETH F.; DAY,DAVID M.

    2000-04-06T23:59:59.000Z

    As computational needs for structural finite element analysis increase, a robust implicit structural dynamics code is needed which can handle millions of degrees of freedom in the model and produce results with quick turn around time. A parallel code is needed to avoid limitations of serial platforms. Salinas is an implicit structural dynamics code specifically designed for massively parallel platforms. It computes the structural response of very large complex structures and provides solutions faster than any existing serial machine. This paper gives a current status of Salinas and uses demonstration problems to show Salinas' performance.

  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 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.

  4. ASCI Red -- Experiences and lessons learned with a massively parallel teraFLOP supercomputer

    SciTech Connect (OSTI)

    Christon, M.A.; Crawford, D.A.; Hertel, E.S.; Peery, J.S.; Robinson, A.C. [Sandia National Labs., Albuquerque, NM (United States). Computational Physics R and D Dept.

    1997-06-01T23:59:59.000Z

    The Accelerated Strategic Computing Initiative (ASCI) program involves Sandia, Los Alamos and Lawrence Livermore National Laboratories. At Sandia National Laboratories, ASCI applications include large deformation transient dynamics, shock propagation, electromechanics, and abnormal thermal environments. In order to resolve important physical phenomena in these problems, it is estimated that meshes ranging from 10{sup 6} to 10{sup 9} grid points will be required. The ASCI program is relying on the use of massively parallel supercomputers initially capable of delivering over 1 TFLOPs to perform such demanding computations. The ASCI Red machine at Sandia National Laboratories consists of over 4,500 computational nodes with a peak computational rate of 1.8 TFLOPs, 567 GBytes of memory, and 2 TBytes of disk storage. Regardless of the peak FLOP rate, there are many issues surrounding the use of massively parallel supercomputers in a production environment. These issues include parallel I/O, mesh generation, visualization, archival storage, high-bandwidth networking and the development of parallel algorithms. In order to illustrate these issues and their solution with respect to ASCI Red, demonstration calculations of time-dependent buoyancy-dominated plumes, electromechanics, and shock propagation will be presented.

  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. A Faster Parallel Algorithm and Efficient Multithreaded Implementations for Evaluating Betweenness Centrality on Massive Datasets

    SciTech Connect (OSTI)

    Madduri, Kamesh; Ediger, David; Jiang, Karl; Bader, David A.; Chavarría-Miranda, Daniel

    2009-05-29T23:59:59.000Z

    We present a new lock-free parallel algorithm for computing betweenness centrality of massive small-world networks. With minor changes to the data structures, our algorithm also achieves better spatial cache locality compared to previous approaches. Betweenness centrality is a key algorithm kernel in the HPCS SSCA#2 Graph Analysis benchmark, which has been extensively used to evaluate the performance of emerging high-performance computing architectures for graph-theoretic computations. We design optimized implementations of betweenness centrality and the SSCA#2 benchmark for two hardware multithreaded systems: a Cray XMT system with the ThreadStorm processor, and a single-socket Sun multicore server with the UltraSparc T2 processor. For a small-world network of 134 million vertices and 1.073 billion edges, the 16-processor XMT system and the 8-core Sun Fire T5120 server achieve TEPS scores (an algorithmic performance count for the SSCA#2 benchmark) of 160 million and 90 million respectively, which corresponds to more than a 2X performance improvement over the previous parallel implementations. To better characterize the performance of these multithreaded systems, we correlate the SSCA#2 performance results with data from the memory-intensive STREAM and RandomAccess benchmarks. Finally, we demonstrate the applicability of our implementation to analyze massive real-world datasets by computing approximate betweenness centrality for a large-scale IMDb movie-actor network.

  7. A Faster Parallel Algorithm and Efficient Multithreaded Implementations for Evaluating Betweenness Centrality on Massive Datasets

    SciTech Connect (OSTI)

    Madduri, Kamesh; Ediger, David; Jiang, Karl; Bader, David A.; Chavarria-Miranda, Daniel

    2009-02-15T23:59:59.000Z

    We present a new lock-free parallel algorithm for computing betweenness centralityof massive small-world networks. With minor changes to the data structures, ouralgorithm also achieves better spatial cache locality compared to previous approaches. Betweenness centrality is a key algorithm kernel in HPCS SSCA#2, a benchmark extensively used to evaluate the performance of emerging high-performance computing architectures for graph-theoretic computations. We design optimized implementations of betweenness centrality and the SSCA#2 benchmark for two hardware multithreaded systems: a Cray XMT system with the Threadstorm processor, and a single-socket Sun multicore server with the UltraSPARC T2 processor. For a small-world network of 134 million vertices and 1.073 billion edges, the 16-processor XMT system and the 8-core Sun Fire T5120 server achieve TEPS scores (an algorithmic performance count for the SSCA#2 benchmark) of 160 million and 90 million respectively, which corresponds to more than a 2X performance improvement over the previous parallel implementations. To better characterize the performance of these multithreaded systems, we correlate the SSCA#2 performance results with data from the memory-intensive STREAM and RandomAccess benchmarks. Finally, we demonstrate the applicability of our implementation to analyze massive real-world datasets by computing approximate betweenness centrality for a large-scale IMDb movie-actor network.

  8. 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.

  9. 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.

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

    SciTech Connect (OSTI)

    Madduri, Kamesh; Bader, David A.

    2009-02-15T23:59:59.000Z

    Graph-theoretic abstractions are extensively used to analyze massive data sets. Temporal data streams from socioeconomic interactions, social networking web sites, communication traffic, and scientific computing can be intuitively modeled as graphs. We present the first study of novel high-performance combinatorial techniques for analyzing large-scale information networks, encapsulating dynamic interaction data in the order of billions of entities. We present new data structures to represent dynamic interaction networks, and discuss algorithms for processing parallel insertions and deletions of edges in small-world networks. With these new approaches, we achieve an average performance rate of 25 million structural updates per second and a parallel speedup of nearly28 on a 64-way Sun UltraSPARC T2 multicore processor, for insertions and deletions to a small-world network of 33.5 million vertices and 268 million edges. We also design parallel implementations of fundamental dynamic graph kernels related to connectivity and centrality queries. Our implementations are freely distributed as part of the open-source SNAP (Small-world Network Analysis and Partitioning) complex network analysis framework.

  11. 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.

  12. A Massively Parallel Sparse Eigensolver for Structural Dynamics Finite Element Analysis

    SciTech Connect (OSTI)

    Day, David M.; Reese, G.M.

    1999-05-01T23:59:59.000Z

    Eigenanalysis is a critical component of structural dynamics which is essential for determinating the vibrational response of systems. This effort addresses the development of numerical algorithms associated with scalable eigensolver techniques suitable for use on massively parallel, distributed memory computers that are capable of solving large scale structural dynamics problems. An iterative Lanczos method was determined to be the best choice for the application. Scalability of the eigenproblem depends on scalability of the underlying linear solver. A multi-level solver (FETI) was selected as most promising for this component. Issues relating to heterogeneous materials, mechanisms and multipoint constraints have been examined, and the linear solver algorithm has been developed to incorporate features that result in a scalable, robust algorithm for practical structural dynamics applications. The resulting tools have been demonstrated on large problems representative of a weapon's system.

  13. 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.

  14. Running ATLAS workloads within massively parallel distributed applications using Athena Multi-Process framework

    E-Print Network [OSTI]

    Calafiura, Paolo; The ATLAS collaboration; Seuster, Rolf; Tsulaia, Vakhtang; van Gemmeren, Peter

    2015-01-01T23:59:59.000Z

    AthenaMP is a multi-process version of the ATLAS reconstruction, simulation and data analysis framework Athena. By leveraging Linux fork and copy-on-write, it allows for sharing of memory pages between event processors running on the same compute node with little to no change in the application code. Originally targeted to optimize the memory footprint of reconstruction jobs, AthenaMP has demonstrated that it can reduce the memory usage of certain configurations of ATLAS production jobs by a factor of 2. AthenaMP has also evolved to become the parallel event-processing core of the recently developed ATLAS infrastructure for fine-grained event processing (Event Service) which allows to run AthenaMP inside massively parallel distributed applications on hundreds of compute nodes simultaneously. We present the architecture of AthenaMP, various strategies implemented by AthenaMP for scheduling workload to worker processes (for example: Shared Event Queue and Shared Distributor of Event Tokens) and the usage of Ath...

  15. 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.

  16. 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.

  17. Massively Parallel Machines. BMC also has the potential to supply massive computational power. General use of BMC is to construct parallel machines where each processor's state is encoded

    E-Print Network [OSTI]

    Reif, John H.

    such as parallel arithmetic. As we discuss in Section 2, DNA in weak solution in one liter of water can encode on these wet databases see Baum B95 and Reif and LaBean RL00 . Organization. In Section 1, we brie ydiscuss

  18. Method and apparatus for obtaining stack traceback data for multiple computing nodes of a massively parallel computer system

    DOE Patents [OSTI]

    Gooding, Thomas Michael (Rochester, MN); McCarthy, Patrick Joseph (Rochester, MN)

    2010-03-02T23:59:59.000Z

    A data collector for a massively parallel computer system obtains call-return stack traceback data for multiple nodes by retrieving partial call-return stack traceback data from each node, grouping the nodes in subsets according to the partial traceback data, and obtaining further call-return stack traceback data from a representative node or nodes of each subset. Preferably, the partial data is a respective instruction address from each node, nodes having identical instruction address being grouped together in the same subset. Preferably, a single node of each subset is chosen and full stack traceback data is retrieved from the call-return stack within the chosen node.

  19. 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.

  20. 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 ...

  1. Massively parallel algorithms for method of characteristics neutral particle transport on shared memory computer architectures

    E-Print Network [OSTI]

    Boyd, William Robert Dawson, III

    2014-01-01T23:59:59.000Z

    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, ...

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. Running ATLAS workloads within massively parallel distributed applications using Athena Multi-Process framework (AthenaMP)

    E-Print Network [OSTI]

    Calafiura, Paolo; The ATLAS collaboration; Seuster, Rolf; Tsulaia, Vakhtang; van Gemmeren, Peter

    2015-01-01T23:59:59.000Z

    AthenaMP is a multi-process version of the ATLAS reconstruction and data analysis framework Athena. By leveraging Linux fork and copy-on-write, it allows the sharing of memory pages between event processors running on the same compute node with little to no change in the application code. Originally targeted to optimize the memory footprint of reconstruction jobs, AthenaMP has demonstrated that it can reduce the memory usage of certain confugurations of ATLAS production jobs by a factor of 2. AthenaMP has also evolved to become the parallel event-processing core of the recently developed ATLAS infrastructure for fine-grained event processing (Event Service) which allows to run AthenaMP inside massively parallel distributed applications on hundreds of compute nodes simultaneously. We present the architecture of AthenaMP, various strategies implemented by AthenaMP for scheduling workload to worker processes (for example: Shared Event Queue and Shared Distributor of Event Tokens) and the usage of AthenaMP in the...

  7. 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.

  8. 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.

  9. Method and apparatus for routing data in an inter-nodal communications lattice of a massively parallel computer system by employing bandwidth shells at areas of overutilization

    DOE Patents [OSTI]

    Archer, Charles Jens; Musselman, Roy Glenn; Peters, Amanda; Pinnow, Kurt Walter; Swartz, Brent Allen; Wallenfelt, Brian Paul

    2010-04-27T23:59:59.000Z

    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 final destination. The default routing strategy is altered responsive to detection of overutilization of a particular path of one or more links, and at least some traffic is re-routed by distributing the traffic among multiple paths (which may include the default path). An alternative path may require a greater number of link traversals to reach the destination node.

  10. Method and apparatus for analyzing error conditions in a massively parallel computer system by identifying anomalous nodes within a communicator set

    DOE Patents [OSTI]

    Gooding, Thomas Michael (Rochester, MN)

    2011-04-19T23:59:59.000Z

    An analytical mechanism for a massively parallel computer system automatically analyzes data retrieved from the system, and identifies nodes which exhibit anomalous behavior in comparison to their immediate neighbors. Preferably, anomalous behavior is determined by comparing call-return stack tracebacks for each node, grouping like nodes together, and identifying neighboring nodes which do not themselves belong to the group. A node, not itself in the group, having a large number of neighbors in the group, is a likely locality of error. The analyzer preferably presents this information to the user by sorting the neighbors according to number of adjoining members of the group.

  11. Method and apparatus for routing data in an inter-nodal communications lattice of a massively parallel computer system by dynamic global mapping of contended links

    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)

    2011-10-04T23:59:59.000Z

    A massively parallel nodal computer system periodically collects and broadcasts usage data for an internal communications network. A node sending data over the network makes a global routing determination using the network usage data. Preferably, network usage data comprises an N-bit usage value for each output buffer associated with a network link. An optimum routing is determined by summing the N-bit values associated with each link through which a data packet must pass, and comparing the sums associated with different possible routes.

  12. Partition-of-unity finite-element method for large scale quantum molecular dynamics on massively parallel computational platforms

    SciTech Connect (OSTI)

    Pask, J E; Sukumar, N; Guney, M; Hu, W

    2011-02-28T23:59:59.000Z

    Over the course of the past two decades, quantum mechanical calculations have emerged as a key component of modern materials research. However, the solution of the required quantum mechanical equations is a formidable task and this has severely limited the range of materials systems which can be investigated by such accurate, quantum mechanical means. The current state of the art for large-scale quantum simulations is the planewave (PW) method, as implemented in now ubiquitous VASP, ABINIT, and QBox codes, among many others. However, since the PW method uses a global Fourier basis, with strictly uniform resolution at all points in space, and in which every basis function overlaps every other at every point, it suffers from substantial inefficiencies in calculations involving atoms with localized states, such as first-row and transition-metal atoms, and requires substantial nonlocal communications in parallel implementations, placing critical limits on scalability. In recent years, real-space methods such as finite-differences (FD) and finite-elements (FE) have been developed to address these deficiencies by reformulating the required quantum mechanical equations in a strictly local representation. However, while addressing both resolution and parallel-communications problems, such local real-space approaches have been plagued by one key disadvantage relative to planewaves: excessive degrees of freedom (grid points, basis functions) needed to achieve the required accuracies. And so, despite critical limitations, the PW method remains the standard today. In this work, we show for the first time that this key remaining disadvantage of real-space methods can in fact be overcome: by building known atomic physics into the solution process using modern partition-of-unity (PU) techniques in finite element analysis. Indeed, our results show order-of-magnitude reductions in basis size relative to state-of-the-art planewave based methods. The method developed here is completely general, applicable to any crystal symmetry and to both metals and insulators alike. We have developed and implemented a full self-consistent Kohn-Sham method, including both total energies and forces for molecular dynamics, and developed a full MPI parallel implementation for large-scale calculations. We have applied the method to the gamut of physical systems, from simple insulating systems with light atoms to complex d- and f-electron systems, requiring large numbers of atomic-orbital enrichments. In every case, the new PU FE method attained the required accuracies with substantially fewer degrees of freedom, typically by an order of magnitude or more, than the current state-of-the-art PW method. Finally, our initial MPI implementation has shown excellent parallel scaling of the most time-critical parts of the code up to 1728 processors, with clear indications of what will be required to achieve comparable scaling for the rest. Having shown that the key remaining disadvantage of real-space methods can in fact be overcome, the work has attracted significant attention: with sixteen invited talks, both domestic and international, so far; two papers published and another in preparation; and three new university and/or national laboratory collaborations, securing external funding to pursue a number of related research directions. Having demonstrated the proof of principle, work now centers on the necessary extensions and optimizations required to bring the prototype method and code delivered here to production applications.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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...

  2. 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

  3. Ultrascalable petaflop parallel supercomputer

    DOE Patents [OSTI]

    Blumrich, Matthias A. (Ridgefield, CT); Chen, Dong (Croton On Hudson, NY); Chiu, George (Cross River, NY); Cipolla, Thomas M. (Katonah, NY); Coteus, Paul W. (Yorktown Heights, NY); Gara, Alan G. (Mount Kisco, NY); Giampapa, Mark E. (Irvington, NY); Hall, Shawn (Pleasantville, NY); Haring, Rudolf A. (Cortlandt Manor, NY); Heidelberger, Philip (Cortlandt Manor, NY); Kopcsay, Gerard V. (Yorktown Heights, NY); Ohmacht, Martin (Yorktown Heights, NY); Salapura, Valentina (Chappaqua, NY); Sugavanam, Krishnan (Mahopac, NY); Takken, Todd (Brewster, NY)

    2010-07-20T23:59:59.000Z

    A massively parallel supercomputer of petaOPS-scale includes node architectures based upon System-On-a-Chip technology, where each processing node comprises a single Application Specific Integrated Circuit (ASIC) having up to four processing elements. The ASIC nodes are interconnected by multiple independent networks that optimally maximize the throughput of packet communications between nodes with minimal latency. The multiple networks may include three high-speed networks for parallel algorithm message passing including a Torus, collective network, and a Global Asynchronous network that provides global barrier and notification functions. These multiple independent networks may be collaboratively or independently utilized according to the needs or phases of an algorithm for optimizing algorithm processing performance. The use of a DMA engine is provided to facilitate message passing among the nodes without the expenditure of processing resources at the node.

  4. Multithreading and Parallel Microprocessors

    E-Print Network [OSTI]

    Shinozuka, Masanobu

    Multithreading and Parallel Microprocessors Stephen Jenks Electrical Engineering and Computer Scalable Parallel and Distributed Systems Lab 4 Outline Parallelism in Microprocessors Multicore Processor Parallelism Parallel Programming for Shared Memory OpenMP POSIX Threads Java Threads Parallel Microprocessor

  5. 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

  6. Parallel MATLAB: Parallel For Loops

    E-Print Network [OSTI]

    Crawford, T. Daniel

    is an extension of MATLAB that takes advantage of multicore desktop machines and clusters. The Parallel Computing work in a simplified kind of MPI model. There is always a special "client" process. Each worker process distributed arrays. A distributed array is logically one array, and a large set of MATLAB commands can treat

  7. Topological Massive Sigma Models

    E-Print Network [OSTI]

    N. D. Lambert

    1995-05-03T23:59:59.000Z

    In this paper we construct topological sigma models which include a potential and are related to twisted massive supersymmetric sigma models. Contrary to a previous construction these models have no central charge and do not require the manifold to admit a Killing vector. We use the topological massive sigma model constructed here to simplify the calculation of the observables. Lastly it is noted that this model can be viewed as interpolating between topological massless sigma models and topological Landau-Ginzburg models.

  8. 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

  9. 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

  10. 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

  11. A Global Optimisation Toolbox for Massively Parallel Engineering Optimisation

    E-Print Network [OSTI]

    Biscani, Francesco; Yam, Chit Hong

    2010-01-01T23:59:59.000Z

    A software platform for global optimisation, called PaGMO, has been developed within the Advanced Concepts Team (ACT) at the European Space Agency, and was recently released as an open-source project. PaGMO is built to tackle high-dimensional global optimisation problems, and it has been successfully used to find solutions to real-life engineering problems among which the preliminary design of interplanetary spacecraft trajectories - both chemical (including multiple flybys and deep-space maneuvers) and low-thrust (limited, at the moment, to single phase trajectories), the inverse design of nano-structured radiators and the design of non-reactive controllers for planetary rovers. Featuring an arsenal of global and local optimisation algorithms (including genetic algorithms, differential evolution, simulated annealing, particle swarm optimisation, compass search, improved harmony search, and various interfaces to libraries for local optimisation such as SNOPT, IPOPT, GSL and NLopt), PaGMO is at its core a C++ ...

  12. 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 ...

  13. 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

  14. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625govInstrumentstdmadapInactiveVisitingContract Management

  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. 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 ...

  17. 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.

  18. 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.

  19. 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...

  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. The STAPL Parallel Container Framework

    E-Print Network [OSTI]

    Tanase, Ilie Gabriel

    2012-02-14T23:59:59.000Z

    The Standard Template Adaptive Parallel Library (STAPL) is a parallel programming infrastructure that extends C with support for parallelism. STAPL provides a run-time system, a collection of distributed data structures (pContainers) and parallel...

  2. Massive Datasets in Astronomy

    E-Print Network [OSTI]

    Robert J. Brunner; S. George Djorgovski; Thomas A. Prince; Alex S. Szalay

    2001-06-26T23:59:59.000Z

    Astronomy has a long history of acquiring, systematizing, and interpreting large quantities of data. Starting from the earliest sky atlases through the first major photographic sky surveys of the 20th century, this tradition is continuing today, and at an ever increasing rate. Like many other fields, astronomy has become a very data-rich science, driven by the advances in telescope, detector, and computer technology. Numerous large digital sky surveys and archives already exist, with information content measured in multiple Terabytes, and even larger, multi-Petabyte data sets are on the horizon. Systematic observations of the sky, over a range of wavelengths, are becoming the primary source of astronomical data. Numerical simulations are also producing comparable volumes of information. Data mining promises to both make the scientific utilization of these data sets more effective and more complete, and to open completely new avenues of astronomical research. Technological problems range from the issues of database design and federation, to data mining and advanced visualization, leading to a new toolkit for astronomical research. This is similar to challenges encountered in other data-intensive fields today. These advances are now being organized through a concept of the Virtual Observatories, federations of data archives and services representing a new information infrastructure for astronomy of the 21st century. In this article, we provide an overview of some of the major datasets in astronomy, discuss different techniques used for archiving data, and conclude with a discussion of the future of massive datasets in astronomy.

  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. Triggered Star Formation in the Environment of Young Massive Stars

    E-Print Network [OSTI]

    M. Gritschneder; T. Naab; F. Heitsch; A. Burkert

    2006-09-26T23:59:59.000Z

    Recent observations with the Spitzer Space Telescope show clear evidence that star formation takes place in the surrounding of young massive O-type stars, which are shaping their environment due to their powerful radiation and stellar winds. In this work we investigate the effect of ionising radiation of massive stars on the ambient interstellar medium (ISM): In particular we want to examine whether the UV-radiation of O-type stars can lead to the observed pillar-like structures and can trigger star formation. We developed a new implementation, based on a parallel Smooth Particle Hydrodynamics code (called IVINE), that allows an efficient treatment of the effect of ionising radiation from massive stars on their turbulent gaseous environment. Here we present first results at very high resolution. We show that ionising radiation can trigger the collapse of an otherwise stable molecular cloud. The arising structures resemble observed structures (e.g. the pillars of creation in the Eagle Nebula (M16) or the Horsehead Nebula B33). Including the effect of gravitation we find small regions that can be identified as formation places of individual stars. We conclude that ionising radiation from massive stars alone can trigger substantial star formation in molecular clouds.

  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. 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.

  10. Parallel MATLAB at VT: Parallel For Loops

    E-Print Network [OSTI]

    Crawford, T. Daniel

    is an extension of MATLAB that takes advantage of multicore desktop machines and clusters. The Parallel Computing work in a simplified kind of MPI model. There is always a special "client" process. Each worker process distributed arrays. A distributed array is logically one array, and a large set of MATLAB commands can treat

  11. 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.

  12. 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

  13. Enabling Rapid Development of Parallel Tree Search Applications

    E-Print Network [OSTI]

    Jeffrey P. Gardner; Andrew Connolly; Cameron McBride

    2007-09-12T23:59:59.000Z

    Virtual observatories will give astronomers easy access to an unprecedented amount of data. Extracting scientific knowledge from these data will increasingly demand both efficient algorithms as well as the power of parallel computers. Nearly all efficient analyses of large astronomical datasets use trees as their fundamental data structure. Writing efficient tree-based techniques, a task that is time-consuming even on single-processor computers, is exceedingly cumbersome on massively parallel platforms (MPPs). Most applications that run on MPPs are simulation codes, since the expense of developing them is offset by the fact that they will be used for many years by many researchers. In contrast, data analysis codes change far more rapidly, are often unique to individual researchers, and therefore accommodate little reuse. Consequently, the economics of the current high-performance computing development paradigm for MPPs does not favor data analysis applications. We have therefore built a library, called Ntropy, that provides a flexible, extensible, and easy-to-use way of developing tree-based data analysis algorithms for both serial and parallel platforms. Our experience has shown that not only does our library save development time, it can also deliver excellent serial performance and parallel scalability. Furthermore, Ntropy makes it easy for an astronomer with little or no parallel programming experience to quickly scale their application to a distributed multiprocessor environment. By minimizing development time for efficient and scalable data analysis, we enable wide-scale knowledge discovery on massive datasets.

  14. 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.

  15. Parallel algorithms for inductance extraction

    E-Print Network [OSTI]

    Mahawar, Hemant

    2007-09-17T23:59:59.000Z

    - figurations involving several conductors within reasonable time. A two-tier parallelization scheme enables mixed mode parallelization, which uses both OpenMP and MPI directives. The parallel performance of the software is demonstrated through experiments...

  16. Superconnections and Parallel Transport

    E-Print Network [OSTI]

    Dumitrescu, Florin

    2007-01-01T23:59:59.000Z

    This note addresses the construction of a notion of parallel transport along superpaths arising from the concept of a superconnection on a vector bundle over a manifold $M$. A superpath in $M$ is, loosely speaking, a path in $M$ together with an odd vector field in $M$ along the path. We also develop a notion of parallel transport associated with a connection (a.k.a. covariant derivative) on a vector bundle over a \\emph{supermanifold} which is a direct generalization of the classical notion of parallel transport for connections over manifolds.

  17. 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).

  18. 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.

  19. 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.

  20. 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.

  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. 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.

  3. 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.

  4. Parallel hierarchical radiosity rendering

    SciTech Connect (OSTI)

    Carter, M.

    1993-07-01T23:59:59.000Z

    In this dissertation, the step-by-step development of a scalable parallel hierarchical radiosity renderer is documented. First, a new look is taken at the traditional radiosity equation, and a new form is presented in which the matrix of linear system coefficients is transformed into a symmetric matrix, thereby simplifying the problem and enabling a new solution technique to be applied. Next, the state-of-the-art hierarchical radiosity methods are examined for their suitability to parallel implementation, and scalability. Significant enhancements are also discovered which both improve their theoretical foundations and improve the images they generate. The resultant hierarchical radiosity algorithm is then examined for sources of parallelism, and for an architectural mapping. Several architectural mappings are discussed. A few key algorithmic changes are suggested during the process of making the algorithm parallel. Next, the performance, efficiency, and scalability of the algorithm are analyzed. The dissertation closes with a discussion of several ideas which have the potential to further enhance the hierarchical radiosity method, or provide an entirely new forum for the application of hierarchical methods.

  5. 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...

  6. Electromagnetic Signatures of Massive Black Hole Binaries

    E-Print Network [OSTI]

    Tamara Bogdanovic; Britton D. Smith; Michael Eracleous; Steinn Sigurdsson

    2006-09-28T23:59:59.000Z

    We model the electromagnetic emission signatures of massive black hole binaries (MBHBs) with an associated gas component. The method comprises numerical simulations of relativistic binaries and gas coupled with calculations of the physical properties of the emitting gas. We calculate the accretion powered UV/X-ray and Halpha light curves and the Halpha emission line profiles. The simulations have been carried out with a modified version of the parallel tree SPH code Gadget. The heating, cooling, and radiative processes for the solar metallicity gas have been calculated with the photoionization code Cloudy. We investigate gravitationally bound, sub-parsec binaries which have not yet entered the gravitational radiation phase. The results from the first set of calculations, carried out for a coplanar binary and gas disk, suggest that the outbursts in the X-ray light curve are pronounced during pericentric passages and can serve as a fingerprint for this type of binaries if periodic outbursts are a long lived signature of the binary. The Halpha emission-line profiles also offer strong indications of a binary presence and may be used as a criterion for selection of MBHB candidates for further monitoring from existing archival data. The orbital period and mass ratio of a binary could be determined from the Halpha light curves and profiles of carefully monitored candidates. Although systems with the orbital periods studied here are not within the frequency band of the Laser Interferometer Space Antenna (LISA), their discovery is important for understanding of the merger rates of MBHBs and the evolution of such binaries through the last parsec and towards the detectable gravitational wave window.

  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. 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.

  9. Parallel Job Scheduling and Workloads

    E-Print Network [OSTI]

    Segall, Adrian

    Parallel Job Scheduling and Workloads Dror Feitelson Hebrew University #12;Parallel Jobs · A set · On multicores: probably more dynamic #12;MPP Parallel Job Scheduling · Each job is a rectangle in processorsXtime space · Given many jobs, we must schedule them to run on available processors · This is like packing

  10. 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.

  11. The evolution of very massive stars

    E-Print Network [OSTI]

    H. Belkus; J. Van Bever; D. Vanbeveren

    2007-01-11T23:59:59.000Z

    Core collapse of dense massive star clusters is unavoidable and this leads to the formation of massive objects, with a mass up to 1000 $\\msun$ and even larger. When these objects become stars, stellar wind mass loss determines their evolution and final fate, and decides upon whether they form black holes (with normal mass or with intermediate mass) or explode as a pair instability supernova. In the present paper, we discuss the evolution of very massive stars and we present a convenient evolution recipe that can be implemented in a gravitational N-body code to study the dynamics of dense massive clusters.

  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. MAGNETIC FIELD IN THE ISOLATED MASSIVE DENSE CLUMP IRAS 20126+4104

    SciTech Connect (OSTI)

    Shinnaga, Hiroko; Phillips, Thomas G. [California Institute of Technology Submillimeter Observatory, 111 Nowelo Street, Hilo, HI 96720 (United States); Novak, Giles [Department of Physics and Astronomy, Northwestern University, 633 Clark Street Evanston, IL 60208 (United States); Vaillancourt, John E. [Stratospheric Observatory for Infrared Astronomy, Universities Space Research Association, NASA Ames Research Center, Moffet Field, CA 94035 (United States); Machida, Masahiro N. [Department of Earth and Planetary Sciences, Faculty of Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan); Kataoka, Akimasa [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Tomisaka, Kohji [National Astronomical Observatory of Japan and Department of Astronomy, School of Physical Sciences, Graduate University for Advanced Studies (SOKENDAI), Osawa 2-21-1, Mitaka, Tokyo 181-8588 (Japan); Davidson, Jacqueline; Houde, Martin [School of Physics, University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Perth (Australia); Dowell, C. Darren [Jet Propulsion Laboratory, California Institute of Technology, MS 169-506, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Leeuw, Lerothodi [SETI Institute, 515 North Whisman Avenue, Mountain View, CA 94043 (United States)

    2012-05-10T23:59:59.000Z

    We measured polarized dust emission at 350 {mu}m toward the high-mass star-forming massive dense clump IRAS 20126+4104 using the SHARC II Polarimeter, SHARP, at the Caltech Submillimeter Observatory. Most of the observed magnetic field vectors agree well with magnetic field vectors obtained from a numerical simulation for the case when the global magnetic field lines are inclined with respect to the rotation axis of the dense clump. The results of the numerical simulation show that rotation plays an important role on the evolution of the massive dense clump and its magnetic field. The direction of the cold CO 1-0 bipolar outflow is parallel to the observed magnetic field within the dense clump as well as the global magnetic field, as inferred from optical polarimetry data, indicating that the magnetic field also plays a critical role in an early stage of massive star formation. The large-scale Keplerian disk of the massive (proto)star rotates in an almost opposite sense to the clump's envelope. The observed magnetic field morphology and the counterrotating feature of the massive dense clump system provide hints to constrain the role of magnetic fields in the process of high-mass star formation.

  14. Detecting torsion from massive electrodynamics

    SciTech Connect (OSTI)

    Garcia de Andrade, L.C.; Lopes, M. (Instituto de Fisica, Rio de Janeiro (Brazil))

    1993-11-01T23:59:59.000Z

    A new method of detecting torsion in the case of massive electrodynamics is proposed. The method is based on the study of spectral lines of hydrogen-like atoms placed in a torsion field, where the interaction energy between the torsion vector field Q and an electric dipole is given by [epsilon] [approximately] p [center dot] Q. All the methods designed so far have been based on spinning test particles interacting with magnetic fields in which the energy splitting is given by [epsilon] [approximately] S [center dot] B on a Stern-Gerlach type experiment. The authors arrive at an energy splitting of order of [epsilon] [approximately] 10[sup [minus]21]erg[approximately]10[sup [minus]9]eV, which is within the frequency band of radio waves. 15 refs.

  15. Speculative Parallelization on Multicore Processors

    E-Print Network [OSTI]

    Tian, Chen

    2010-01-01T23:59:59.000Z

    and they include bayes, kmeans, labyrinth, vacation, andcenter update PVECTOR None kmeans labyrinth vacation yada I-parallel threads are bayes kmeans labyrinth vacation yada

  16. 8/30/2001 Parallel Programming -Fall 2001 1 Models of Parallel Computation

    E-Print Network [OSTI]

    Browne, James C.

    8/30/2001 Parallel Programming - Fall 2001 1 Models of Parallel Computation Philosophy Parallel of parallel programming. #12;8/30/2001 Parallel Programming - Fall 2001 2 Models of Parallel Computation will discuss parallelism from the viewpoint of programming but with connections to other domains. #12;8/30/2001

  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 execution model for Prolog

    SciTech Connect (OSTI)

    Fagin, B.S.

    1987-01-01T23:59:59.000Z

    One candidate language for parallel symbolic computing is Prolog. Numerous ways for executing Prolog in parallel have been proposed, but current efforts suffer from several deficiencies. Many cannot support fundamental types of concurrency in Prolog. Other models are of purely theoretical interest, ignoring implementation costs. Detailed simulation studies of execution models are scare; at present little is known about the costs and benefits of executing Prolog in parallel. In this thesis, a new parallel execution model for Prolog is presented: the PPP model or Parallel Prolog Processor. The PPP supports AND-parallelism, OR-parallelism, and intelligent backtracking. An implementation of the PPP is described, through the extension of an existing Prolog abstract machine architecture. Several examples of PPP execution are presented, and compilation to the PPP abstract instruction set is discussed. The performance effects of this model are reported, based on a simulation of a large benchmark set. The implications of these results for parallel Prolog systems are discussed, and directions for future work are indicated.

  19. Parallel Computing Daniel S. Priece

    E-Print Network [OSTI]

    performance on multiprocessor systems. This paper reviews the fundamentals of parallel computing with a focus. Today the most powerful computer is able to use 20 teraflops of processing power [1]. Rapid hardware execute in 8 hours could be executed on a parallel system of 8 processors in one hour greatly reducing

  20. 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.

  1. Top 10 Problems on Massive Stars

    E-Print Network [OSTI]

    Cassio Barbosa; Donald Figer

    2005-10-18T23:59:59.000Z

    We have asked a number of researchers to compile their lists of the top 10 problems in the field of massive stars. This paper is a compilation of these lists. We attempted to survey observers and theorists and those studying all evolutionary stages in the lives of massive stars. Each list reflects the proposer's personal point of view, but hopefully, this compilation will motivate new young astronomers and begin a new series of discussion.

  2. 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

  3. An Example-Based Translation System on a Massively Parallel Machine Satoshi SATO

    E-Print Network [OSTI]

    Mitsunaga, Noriaki

    $K¡($9!#MBT3 $N¡B9T7O$O!"1) FbItK]Lu%G!¡%?%Y!¡%9!"2) :GE,¿H9g8!:w4o!"3) K]Lu%3%s %H%m!¡%i$N3 $D$N%b%8$r8!:wF~NO$H$7!":GE,¿H9g8!:w$r¡B9T$9$k!#$= $N7k2L$H$7$F!"%G!¡%?%Y!¡%9$+$i8!:wF~NO$KNI$/;w $? N(= 10% [Sato, 1993a] $r;2¿H$7$F$[$7$$!# 3 MBT3n: nCUBE2 ¿e$NMBT3 MBT3n $G$O!":GE,¿H9g8!:w$r¡B9T$9$kItJ,(A0@a%9

  4. Massively-parallel electrical-conductivity imaging of hydrocarbons using the Blue Gene/L supercomputer

    E-Print Network [OSTI]

    2008-01-01T23:59:59.000Z

    CONDUCTIVITY IMAGING OF HYDROCARBONS USING THE BLUE GENE/Lidentification of hydrocarbon filled layers in deepwater,”Remote sensing of hydrocarbon layers by seabed logging (

  5. A Scalable Parallel Subspace Clustering Algorithm for Massive Data Sets Harsha S Nagesh

    E-Print Network [OSTI]

    Initiative (ASCI) program under a subcontract No W-7405-ENG-48 from Lawarence Livermore national Laboratories

  6. 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.

  7. 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

  8. 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

  9. Supernova emulators: connecting massively parallel SN Ia radiative transfer simulations to data with Gaussian processes

    E-Print Network [OSTI]

    Backer, Don

    (M ) 0.32 0.31 RNi (M ) 0.35 0.35 MIME (M ) 0.87 0.80 MCO (M ) 0.13 0.19 (cm2 g-1 ) 0.15 0.15 SMOKE ) 0.0 0.6 1.2 1.8 Sim. Params True Fit MNi (M ) 0.51 0.51 RNi (M ) 0.87 0.89 MIME (M ) 0.12 0.16 MCO.97 MIME (M ) 0.01 0.03 MCO (M ) 0.65 0.67 (cm2 g-1 ) 0.16 0.15 0 20 40 60 80 100 Days Since Explosion -3

  10. 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...

  11. 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...

  12. 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 ...

  13. Massively-parallel electrical-conductivity imaging of hydrocarbons using the Blue Gene/L supercomputer

    E-Print Network [OSTI]

    2008-01-01T23:59:59.000Z

    Research) since 1991, primarily in seismic interpretationand seismic attribute analysis. interpretation of CSEM data

  14. 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 ...

  15. Chapter 3 Massively Parallel Molecular Simulation Program 3.1 Introduction

    E-Print Network [OSTI]

    Goddard III, William A.

    _Reduce. The flow chart for the current implementation using the simplest MPI calls is given in Appendix A. 3 The basic structure of the MPSim program is shown on Fig 3.1. Fig 3.2 depicts the structure of the energy in Lim et.al. Here is an example of using the "pull" strategy to compute the kinetic energy of a system

  16. Proof-of-concept implementation of the massively parallel algorithm for simulation of

    E-Print Network [OSTI]

    Lushnikov, Pavel

    latency of nodes interconnection media. The experimental data shows [7] that at a number of harmonics up with SS. The results are in full agreement with numerics. We neglect polarization effects, stimulated

  17. Massively-parallel electrical-conductivity imaging of hydrocarbons using the Blue Gene/L supercomputer

    E-Print Network [OSTI]

    2008-01-01T23:59:59.000Z

    OF HYDROCARBONS USING THE BLUE GENE/L SUPERCOMPUTER M.of the sail lines (red and blue) and 23 detector locations (detector arrays marked in blue. Figure 3. Six selected plots

  18. Massively-parallel electrical-conductivity imaging of hydrocarbons using the Blue Gene/L supercomputer

    E-Print Network [OSTI]

    2008-01-01T23:59:59.000Z

    reservoirs,” Trans. Soc. Petrol. Well-Log Analysts (SPWLA);of rocks,” Trans. Soc. Petrol. Well-Log Analysts (SPWLA);

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

    E-Print Network [OSTI]

    Unat, Didem

    2012-01-01T23:59:59.000Z

    Performance Impact of Nest and Tile Clauses . . . 7.1.7A 3D grid is broken into 3D tiles basedon the tile clause. A thread block computes a tile. Elements

  20. Diffuse large B-cell lymphoma: sub-classification by massive parallel quantitative RT-PCR

    E-Print Network [OSTI]

    Xue, Xuemin; Zeng, Naiyan; Gao, Zifen; Du, Ming-Qing

    2014-11-24T23:59:59.000Z

    The research in Du lab was supported by research grants (LLR10006 & LLR13006) from Leukaemia & Lymphoma Research, U.K.. XX was supported by a visiting fellowship from the China Scholarship Council, Ministry of Education, P.R. China. 2 ABSTRACT... , were retrieved and used for construction and validation of DLBCL classifier: the FF dataset by Lymphochip (http://llmpp.nih.gov/DLBCLpredictor/),3 the FF dataset (GSE10846: this was further split according to treatment with CHOP or R...

  1. CASL-U-2015-0170-000 SHIFT: A Massively Parallel Monte Carlo

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office511041clothAdvanced Materials Advanced. C o w l i t z C o . C l a r k C o .7-0007-000 COBRA-TF SHIFT: A

  2. 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)

  3. A Parallel Graph Partitioner for STAPL

    E-Print Network [OSTI]

    Castet, Nicolas

    2013-04-26T23:59:59.000Z

    high-level framework to develop parallel applications. One of the first steps of a parallel application is to partition and distribute the data throughout the system. An important data structure for parallel applications to store large amounts of data...

  4. Instrumentation for parallel magnetic resonance imaging

    E-Print Network [OSTI]

    Brown, David Gerald

    2007-04-25T23:59:59.000Z

    Parallel magnetic resonance (MR) imaging may be used to increase either the throughput or the speed of the MR imaging experiment. As such, parallel imaging may be accomplished either through a "parallelization" of the MR experiment, or by the use...

  5. 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

  6. Chemical Enrichment from Massive Stars in Starbursts

    E-Print Network [OSTI]

    Henry A. Kobulnicky

    1999-01-20T23:59:59.000Z

    The warm ionized gas in low-mass, metal-poor starforming galaxies is chemically homogeneous despite the prevalence of large H II regions which contain hundreds of evolved massive stars, supernovae, and Wolf-Rayet stars with chemically-enriched winds. Galaxies with large Wolf-Rayet star content are chemically indistinguishable from other vigorously star-forming galaxies. Furthermore, no significant localized chemical fluctuations are present in the vicinity of young star clusters, despite large expected chemical yields of massive stars. An ad-hoc fine-tuning of the release, dispersal and mixing of the massive star ejecta could give rise to the observed homogeneity, but a more probable explanation is that fresh ejecta from massive stars reside in a hard-to-observe hot or cold phase. In any case, the observed chemical homogeneity indicates that heavy elements which have already mixed with the warm interstellar medium (thus accessible to optical spectroscopy) are homogeneously dispersed over scales exceeding 1 kpc. Mixing of fresh ejecta with the surrounding warm ISM apparently requires longer than the lifetimes of typical H II regions (>10^7 yrs). The lack of observed localized chemical enrichments is consistent with a scenario whereby freshly-synthesized metals from massive stars are expelled into the halos of galaxies in a hot, 10^6 K phase by supernova-driven winds before they cool and ``rain'' back down upon the galaxy, creating gradual enrichments on spatial scales >1 kpc.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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, $\

  14. 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

  15. Gravitational stability of finite massive bodies

    E-Print Network [OSTI]

    A. W. Zaharow

    2006-10-16T23:59:59.000Z

    Jeans instability of finite massive bodies at hydrostatic equilibrium is studied. Differential equation governing the evolution of infinitesimal disturbances is derived. We take into account radial inhomogeneity of mass density and other fluid parameters at the equilibrium state. Dispersion relation and a simple analytical formula, generalizing the Jeans criterion of instability, are derived.

  16. 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...

  17. Parallelization and checkpointing of GPU applications through program transformation

    SciTech Connect (OSTI)

    Solano-Quinde, Lizandro Dami#19; an [Ames Laboratory

    2012-11-15T23:59:59.000Z

    GPUs have emerged as a powerful tool for accelerating general-purpose applications. The availability of programming languages that makes writing general-purpose applications for running on GPUs tractable have consolidated GPUs as an alternative for accelerating general purpose applications. Among the areas that have beneffited from GPU acceleration are: signal and image processing, computational fluid dynamics, quantum chemistry, and, in general, the High Performance Computing (HPC) Industry. In order to continue to exploit higher levels of parallelism with GPUs, multi-GPU systems are gaining popularity. In this context, single-GPU applications are parallelized for running in multi-GPU systems. Furthermore, multi-GPU systems help to solve the GPU memory limitation for applications with large application memory footprint. Parallelizing single-GPU applications has been approached by libraries that distribute the workload at runtime, however, they impose execution overhead and are not portable. On the other hand, on traditional CPU systems, parallelization has been approached through application transformation at pre-compile time, which enhances the application to distribute the workload at application level and does not have the issues of library-based approaches. Hence, a parallelization scheme for GPU systems based on application transformation is needed. Like any computing engine of today, reliability is also a concern in GPUs. GPUs are vulnerable to transient and permanent failures. Current checkpoint/restart techniques are not suitable for systems with GPUs. Checkpointing for GPU systems present new and interesting challenges, primarily due to the natural differences imposed by the hardware design, the memory subsystem architecture, the massive number of threads, and the limited amount of synchronization among threads. Therefore, a checkpoint/restart technique suitable for GPU systems is needed. The goal of this work is to exploit higher levels of parallelism and to develop support for application-level fault tolerance in applications using multiple GPUs. Our techniques reduce the burden of enhancing single-GPU applications to support these features. To achieve our goal, this work designs and implements a framework for enhancing a single-GPU OpenCL application through application transformation.

  18. Efficient Coordinated Recovery of Sparse Channels in Massive MIMO

    E-Print Network [OSTI]

    Al-Naffouri, Tareq Y.

    estimation of large number of channels in massive MIMO systems. Moreover, to avoid pilot contamination University of Petroleum and Minerals, Dhahran 31261, Kingdom of Saudi Arabia. Moreover, in massive MIMO

  19. Coupled parallel waveguide semiconductor laser

    SciTech Connect (OSTI)

    Mukai, S.; Kapon, E.; Katz, J.; Lindsey, C.; Rav-Noy, Z.; Margalit, S.; Yariv, A.

    1984-03-01T23:59:59.000Z

    The operation of a new type of tunable laser, where the two separately controlled individual lasers are placed vertically in parallel, has been demonstrated. One of the cavities (''control'' cavity) is operated below threshold and assists the longitudinal mode selection and tuning of the other laser. With a minor modification, the same device can operate as an independent two-wavelength laser source.

  20. 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.

  1. A High-Performance Hybrid Computing Approach to Massive Contingency Analysis in the Power Grid

    SciTech Connect (OSTI)

    Gorton, Ian; Huang, Zhenyu; Chen, Yousu; Kalahar, Benson K.; Jin, Shuangshuang; Chavarría-Miranda, Daniel; Baxter, Douglas J.; Feo, John T.

    2009-12-01T23:59:59.000Z

    Operating the electrical power grid to prevent power black-outs is a complex task. An important aspect of this is contingency analysis, which involves understanding and mitigating potential failures in power grid elements such as transmission lines. When taking into account the potential for multiple simultaneous failures (known as the N-x contingency problem), contingency analysis becomes a massively computational task. In this paper we describe a novel hybrid computational approach to contingency analysis. This approach exploits the unique graph processing performance of the Cray XMT in conjunction with a conventional massively parallel compute cluster to identify likely simultaneous failures that could cause widespread cascading power failures that have massive economic and social impact on society. The approach has the potential to provide the first practical and scalable solution to the N-x contingency problem. When deployed in power grid operations, it will increase the grid operator’s ability to deal effectively with outages and failures with power grid components while preserving stable and safe operation of the grid. The paper describes the architecture of our solution and presents preliminary performance results that validate the efficacy of our approach.

  2. 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 \

  3. Implementing a parallel C++ runtime system for scalable parallel systems

    SciTech Connect (OSTI)

    Bodin, F. [Univ. of Rennes (France); Beckman, P.; Gannon, D.; Yang, S. [Indiana Univ., Bloomington, IN (United States); Kesavan, S.; Malony, A.; Mohr, B. [Univ. of Oregon, Eugene, OR (United States)

    1993-12-31T23:59:59.000Z

    pC++ is a language extension to C++ designed to allow programmers to compose ``concurrent aggregate`` collection classes which can be aligned and distributed over the memory hierarchy of a parallel machine in a manner modeled on the High Performance Fortran Forum (HPFF) directives for Fortran 90. pC++ allows the user to write portable and efficient code which will run on a wide range of scalable parallel computer systems. The first version of the compiler is a preprocessor which generates Single Program Multiple Data (SPMD) C++ code. Currently, it runs on the Thinking Machines CM-5, the Intel Paragon, the BBN TC2000, the Kendall Square Research KSR-1, and the Sequent Symmetry. In this paper the authors describe the implementation of the runtime system, which provides the concurrency and communication primitives between objects in a distributed collection. To illustrate the behavior of the runtime system they include a description and performance results on four benchmark programs.

  4. 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.

  5. 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.

  6. 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.

  7. Parallel self-mixing imaging system based on an array of vertical-cavity surface-emitting lasers

    SciTech Connect (OSTI)

    Tucker, John R.; Baque, Johnathon L.; Lim, Yah Leng; Zvyagin, Andrei V.; Rakic, Aleksandar D

    2007-09-01T23:59:59.000Z

    In this paper we investigate the feasibility of a massively parallel self-mixing imaging system based on an array of vertical-cavity surface-emitting lasers (VCSELs) to measure surface profiles of displacement,distance, velocity, and liquid flow rate. The concept of the system is demonstrated using a prototype to measure the velocity at different radial points on a rotating disk, and the velocity profile of diluted milk in a custom built diverging-converging planar flow channel. It is envisaged that a scaled up version of the parallel self-mixing imaging system will enable real-time surface profiling, vibrometry, and flowmetry.

  8. Gauge invariance and massive torsionic scalar field

    E-Print Network [OSTI]

    Nikodem J. Poplawski

    2006-08-11T23:59:59.000Z

    The Hojman-Rosenbaum-Ryan-Shepley dynamical theory of torsion preserves local gauge invariance of electrodynamics and makes minimal coupling compatible with torsion. It also allows propagation of torsion in vacuum. It is known that implications of this model disagree with the Eotvos-Dicke-Braginsky solar tests of the principle of equivalence. We modify this theory and make it consistent with experiment by introducing a massive component of the torsionic potential.

  9. Torsion and gauge-invariant massive electrodynamics

    SciTech Connect (OSTI)

    Sabbata, V. de (Univ. of Ferrara, Sezione di Ferrara (Italy)); Sivaram, C. (Institute of Astrophysics, Bangalore (India)); Andrade, L.G. de (Instituto de Fisica, Rio de Janeiro (Brazil))

    1993-09-01T23:59:59.000Z

    The authors study electrodynamics in Einstein-Cartan space-time, that is, in space-time with torsion, and show an analogy with the Chern-Simons gauge-invariant massive electrodynamics. In their case, however, there is no arbitrary parameter, the torsion Q playing the role of the Chern-Simons parameter k. This leads to bounds on the photon mass, charge, and torsion coupling.

  10. On the formation of massive stellar clusters

    E-Print Network [OSTI]

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

    2003-08-25T23:59:59.000Z

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

  11. 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.

  12. 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.

  13. On the formation of massive stellar clusters

    E-Print Network [OSTI]

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

    2003-01-01T23:59:59.000Z

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

  14. 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

  15. Parallelism Constraints Katrin Erk Joachim Niehren

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Parallelism Constraints Katrin Erk Joachim Niehren Programming Systems Lab, Universit¨at des Saarlandes, Saarbr¨ucken, Germany www.ps.uni-sb.de/~{erk,niehren} Abstract. Parallelism constraints

  16. 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 ...

  17. Optimization Online - Efficient parallel coordinate descent algorithm ...

    E-Print Network [OSTI]

    Ion Necoara

    2012-11-02T23:59:59.000Z

    Nov 2, 2012 ... Efficient parallel coordinate descent algorithm for convex optimization problems with separable constraints: application to distributed MPC.

  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. Parallel Computing Research at Illinois The UPCRC Agenda

    E-Print Network [OSTI]

    @Illinois(www.parallel.illinois.edu)isthecollectiverepresentationofIllinois'currenteffortsin parallel computing research and education. These include: · UniversalParallelComputingResearchCenter · BlueWaters

  20. 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.

  1. 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...

  2. 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.

  3. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible for RenewableSpeedingBiomassPPPO WebsitePalms Village Resort B a

  4. 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

  5. A parallel execution model for Prolog

    SciTech Connect (OSTI)

    Fagin, B.

    1987-01-01T23:59:59.000Z

    In this thesis a new parallel execution model for Prolog is presented: The PPP model or Parallel Prolog Processor. The PPP supports AND-parallelism, OR- parallelism, and intelligent backtracking. An implementation of the PPP is described, through the extension of an existing Prolog abstract machine architecture. Several examples of PPP execution are presented and compilation to the PPP abstract instructions set is discussed. The performance effects of this model are reported, based on a simulation of a large benchmark set. The implications of these results for parallel Prolog systems are discussed, and directions for future work are indicated.

  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. A new quasidilaton theory of massive gravity

    E-Print Network [OSTI]

    Shinji Mukohyama

    2014-10-08T23:59:59.000Z

    We present a new quasidilaton theory of Poincare invariant massive gravity, based on the recently proposed framework of matter coupling that makes it possible for the kinetic energy of the quasidilaton scalar to couple to both physical and fiducial metrics simultaneously. We find a scaling-type exact solution that expresses a self-accelerating de Sitter universe, and then analyze linear perturbations around it. It is shown that in a range of parameters all physical degrees of freedom have non-vanishing quadratic kinetic terms and are stable in the subhorizon limit, while the effective Newton's constant for the background is kept positive.

  8. 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.

  9. 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.

  10. Drag phenomena from holographic massive gravity

    E-Print Network [OSTI]

    Matteo Baggioli; Daniel K. Brattan

    2015-04-28T23:59:59.000Z

    We consider the motion of point particles in a strongly coupled field theory with broken translation invariance. We obtain the energy and momentum loss rates and drag coefficients for a class of such particles by solving for the motion of classical strings in holographic massive gravity. At low temperatures compared to the graviton mass the behaviour of the string is controlled by the appearance of an exotic ground state with non-zero entropy at zero temperature. Additionally we find an upper bound on the diffusion constant for a collection of these particles which is saturated when the mass of the graviton goes to zero.

  11. Drag phenomena from holographic massive gravity

    E-Print Network [OSTI]

    Baggioli, Matteo

    2015-01-01T23:59:59.000Z

    We consider the motion of point particles in a strongly coupled field theory with broken translation invariance. We obtain the energy and momentum loss rates and drag coefficients for a class of such particles by solving for the motion of classical strings in holographic massive gravity. At low temperatures compared to the graviton mass the behaviour of the string is controlled by the appearance of an exotic ground state with non-zero entropy at zero temperature. Additionally we find an upper bound on the diffusion constant for a collection of these particles which is saturated when the mass of the graviton goes to zero.

  12. 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.

  13. 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.

  14. 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.

  15. Knowledge Discovery from Massive Healthcare Claims Data

    SciTech Connect (OSTI)

    Chandola, Varun [ORNL] [ORNL; Sukumar, Sreenivas R [ORNL] [ORNL; Schryver, Jack C [ORNL] [ORNL

    2013-01-01T23:59:59.000Z

    The role of big data in addressing the needs of the present healthcare system in US and rest of the world has been echoed by government, private, and academic sectors. There has been a growing emphasis to explore the promise of big data analytics in tapping the potential of the massive healthcare data emanating from private and government health insurance providers. While the domain implications of such collaboration are well known, this type of data has been explored to a limited extent in the data mining community. The objective of this paper is two fold: first, we introduce the emerging domain of big"healthcare claims data to the KDD community, and second, we describe the success and challenges that we encountered in analyzing this data using state of art analytics for massive data. Specically, we translate the problem of analyzing healthcare data into some of the most well-known analysis problems in the data mining community, social network analysis, text mining, and temporal analysis and higher order feature construction, and describe how advances within each of these areas can be leveraged to understand the domain of healthcare. Each case study illustrates a unique intersection of data mining and healthcare with a common objective of improving the cost-care ratio by mining for opportunities to improve healthcare operations and reducing hat seems to fall under fraud, waste,and abuse.

  16. Massive Science with VO and Grids

    E-Print Network [OSTI]

    Robert Nichol; Garry Smith; Christopher Miller; Peter Freeman; Chris Genovese; Larry Wasserman; Brent Bryan; Alexander Gray; Jeff Schneider; Andrew Moore

    2005-10-31T23:59:59.000Z

    There is a growing need for massive computational resources for the analysis of new astronomical datasets. To tackle this problem, we present here our first steps towards marrying two new and emerging technologies; the Virtual Observatory (e.g, AstroGrid) and the computational grid (e.g. TeraGrid, COSMOS etc.). We discuss the construction of VOTechBroker, which is a modular software tool designed to abstract the tasks of submission and management of a large number of computational jobs to a distributed computer system. The broker will also interact with the AstroGrid workflow and MySpace environments. We discuss our planned usages of the VOTechBroker in computing a huge number of n-point correlation functions from the SDSS data and massive model-fitting of millions of CMBfast models to WMAP data. We also discuss other applications including the determination of the XMM Cluster Survey selection function and the construction of new WMAP maps.

  17. 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.

  18. 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).

  19. 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.

  20. 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).

  1. Optimization Online - Efficient Serial and Parallel Coordinate ...

    E-Print Network [OSTI]

    Peter Richtarik

    2011-08-02T23:59:59.000Z

    Aug 2, 2011 ... Efficient Serial and Parallel Coordinate Descent Methods for Huge-Scale Truss Topology Design. Peter Richtarik(peter.richtarik ***at*** ...

  2. Parallel Interval Continuous Global Optimization Algorithms

    E-Print Network [OSTI]

    abdeljalil benyoub

    2002-07-19T23:59:59.000Z

    Jul 19, 2002 ... Abstract: We theorically study, on a distributed memory architecture, the parallelization of Hansen's algorithm for the continuous global ...

  3. 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.

  4. 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...

  5. 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 ...

  6. 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 \

  7. 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.

  8. Massive superstring scatterings in the Regge regime

    SciTech Connect (OSTI)

    He Song; Lee, Jen-Chi; Takahashi, Keijiro; Yang Yi [Institute of High Energy Physics, Chinese Academic of Sciences, Beijing (China); Department of Electrophysics, National Chiao-Tung University and Physics Division, National Center for Theoretical Sciences, Hsinchu, Taiwan (China); Department of Electrophysics, National Chiao-Tung University, Hsinchu, Taiwan (China); Department of Electrophysics, National Chiao-Tung University and Physics Division, National Center for Theoretical Sciences, Hsinchu, Taiwan (China)

    2011-03-15T23:59:59.000Z

    We calculate four classes of high-energy massive string scattering amplitudes of fermionic string theory at arbitrary mass levels in the Regge regime (RR). We show that all four leading order amplitudes in the RR can be expressed in terms of the Kummer function of the second kind. Based on the summation algorithm of a set of extended signed Stirling number identities, we show that all four ratios calculated previously by the method of decoupling of zero-norm states among scattering amplitudes in the Gross regime can be extracted from this Kummer function in the RR. Finally, we conjecture and give evidence that the existence of these four Gross regime ratios in the RR persists to subleading orders in the Regge expansion of all high-energy fermionic string scattering amplitudes.

  9. Efficient Algorithms for Parallel Excitation and Parallel Imaging with Large Arrays 

    E-Print Network [OSTI]

    Feng, Shuo

    2013-08-12T23:59:59.000Z

    RF signals using phased arrays are called parallel excitation (pTx) and parallel imaging (PI), respectively. These two techniques lead to shorter transmit pulses for higher imaging quality and faster data acquisition correspondingly...

  10. Parallel computing in enterprise modeling.

    SciTech Connect (OSTI)

    Goldsby, Michael E.; Armstrong, Robert C.; Shneider, Max S.; Vanderveen, Keith; Ray, Jaideep; Heath, Zach; Allan, Benjamin A.

    2008-08-01T23:59:59.000Z

    This report presents the results of our efforts to apply high-performance computing to entity-based simulations with a multi-use plugin for parallel computing. We use the term 'Entity-based simulation' to describe a class of simulation which includes both discrete event simulation and agent based simulation. What simulations of this class share, and what differs from more traditional models, is that the result sought is emergent from a large number of contributing entities. Logistic, economic and social simulations are members of this class where things or people are organized or self-organize to produce a solution. Entity-based problems never have an a priori ergodic principle that will greatly simplify calculations. Because the results of entity-based simulations can only be realized at scale, scalable computing is de rigueur for large problems. Having said that, the absence of a spatial organizing principal makes the decomposition of the problem onto processors problematic. In addition, practitioners in this domain commonly use the Java programming language which presents its own problems in a high-performance setting. The plugin we have developed, called the Parallel Particle Data Model, overcomes both of these obstacles and is now being used by two Sandia frameworks: the Decision Analysis Center, and the Seldon social simulation facility. While the ability to engage U.S.-sized problems is now available to the Decision Analysis Center, this plugin is central to the success of Seldon. Because Seldon relies on computationally intensive cognitive sub-models, this work is necessary to achieve the scale necessary for realistic results. With the recent upheavals in the financial markets, and the inscrutability of terrorist activity, this simulation domain will likely need a capability with ever greater fidelity. High-performance computing will play an important part in enabling that greater fidelity.

  11. 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.

  12. Towards Efficient Query Processing on Massive Time-Evolving Graphs

    E-Print Network [OSTI]

    Miller, John A.

    Email: {ar, ara, laks, jam}@cs.uga.edu Abstract--Time evolving graph (TEG) is increasingly being used on massive TEGs is central to building powerful analytic applications for these domains. Unfortunately effective for processing massive TEGs. Towards designing scalable mechanisms for answering TEG queries

  13. Cosmological evolutions of $F(R)$ nonlinear massive gravity

    E-Print Network [OSTI]

    De-Jun Wu

    2014-03-24T23:59:59.000Z

    Recently a new extended nonlinear massive gravity model has been proposed which includes the $F(R)$ modifications to dRGT model.We follow the $F(R)$ nonlinear massive gravity and study its implications on cosmological evolutions. We derive the critical points of the cosmic system and study the corresponding kinetics by performing the phase-plane analysis.

  14. 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

  15. Limiting Accretion onto Massive Stars by Fragmentation-Induced Starvation

    SciTech Connect (OSTI)

    Peters, Thomas; /ZAH, Heidelberg; Klessen, Ralf S.; /ZAH, Heidelberg /KIPAC, Menlo Park; Mac Low, Mordecai-Mark; /Amer. Museum Natural Hist.; Banerjee, Robi; /ZAH, Heidelberg

    2010-08-25T23:59:59.000Z

    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 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.

  16. Creating a Parallel Version of VisIt for Microsoft Windows

    SciTech Connect (OSTI)

    Whitlock, B J; Biagas, K S; Rawson, P L

    2011-12-07T23:59:59.000Z

    VisIt is a popular, free interactive parallel visualization and analysis tool for scientific data. Users can quickly generate visualizations from their data, animate them through time, manipulate them, and save the resulting images or movies for presentations. VisIt was designed from the ground up to work on many scales of computers from modest desktops up to massively parallel clusters. VisIt is comprised of a set of cooperating programs. All programs can be run locally or in client/server mode in which some run locally and some run remotely on compute clusters. The VisIt program most able to harness today's computing power is the VisIt compute engine. The compute engine is responsible for reading simulation data from disk, processing it, and sending results or images back to the VisIt viewer program. In a parallel environment, the compute engine runs several processes, coordinating using the Message Passing Interface (MPI) library. Each MPI process reads some subset of the scientific data and filters the data in various ways to create useful visualizations. By using MPI, VisIt has been able to scale well into the thousands of processors on large computers such as dawn and graph at LLNL. The advent of multicore CPU's has made parallelism the 'new' way to achieve increasing performance. With today's computers having at least 2 cores and in many cases up to 8 and beyond, it is more important than ever to deploy parallel software that can use that computing power not only on clusters but also on the desktop. We have created a parallel version of VisIt for Windows that uses Microsoft's MPI implementation (MSMPI) to process data in parallel on the Windows desktop as well as on a Windows HPC cluster running Microsoft Windows Server 2008. Initial desktop parallel support for Windows was deployed in VisIt 2.4.0. Windows HPC cluster support has been completed and will appear in the VisIt 2.5.0 release. We plan to continue supporting parallel VisIt on Windows so our users will be able to take full advantage of their multicore resources.

  17. 3: Parallelism in Microprocessors Course on "Scalable Computing". Vittorio Scarano 3: Parallelism in Microprocessors

    E-Print Network [OSTI]

    Scarano, Vittorio

    3: Parallelism in Microprocessors Course on "Scalable Computing". Vittorio Scarano 3: Parallelism in Microprocessors Seminars in Scalable Computing Vittorio Scarano Universit`a di Salerno Dottorato di Ricerca in Informatica 1/65 3: Parallelism in Microprocessors Course on "Scalable Computing". Vittorio Scarano Plan 1

  18. A New Approach to Parallel Program Development and Scheduling of Parallel Jobs on Distributed Systems

    E-Print Network [OSTI]

    of Technology Abstract A typical way to increase the performance of a parallel program on a given parallel an initial and time- consuming development phase. We propose an alter- native approach to program development of Energy through Los Alamos National Laboratory contract W-7405-ENG-36 parallel scheduling algorithms

  19. ASYNPLEX, an asynchronous parallel revised simplex algorithm

    E-Print Network [OSTI]

    Hall, Julian

    ASYNPLEX, an asynchronous parallel revised simplex algorithm J.A.J. Hall K.I.M. McKinnon February, an asynchronous parallel revised simplex algorithm J. A. J. Hall K. I. M. McKinnon 27th February 1998 Abstract This paper describes ASYNPLEX, an asynchronous variant of the revised simplex method which is suitable

  20. Addendum to "Superconnections and Parallel Transport"

    E-Print Network [OSTI]

    Dumitrescu, Florin

    2011-01-01T23:59:59.000Z

    In this addendum to our article "Superconnections and Parallel Transport" we give an alternate construction to the parallel transport of a superconnection contained in Corollary 4.4 of \\cite{D1}, which has the advantage that is independent on the various ways a superconnection splits as a connection plus a bundle endomorphism valued form.

  1. ETH Zurich A Parallel Hybrid Particle

    E-Print Network [OSTI]

    Hiptmair, Ralf

    ] and POOMA (Parallel Object-Oriented Methods and Applications) [3] are designed to support a single execution model at a time and provide only MPI (Message Passing Interface) or shared mem- ory parallel programming compute powers and bandwidths are not taken into account which in turn can prevent good load balancing

  2. 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

  3. 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

  4. 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

  5. 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.

  6. System and method for a parallel immunoassay system

    DOE Patents [OSTI]

    Stevens, Fred J. (Naperville, IL)

    2002-01-01T23:59:59.000Z

    A method and system for detecting a target antigen using massively parallel immunoassay technology. In this system, high affinity antibodies of the antigen are covalently linked to small beads or particles. The beads are exposed to a solution containing DNA-oligomer-mimics of the antigen. The mimics which are reactive with the covalently attached antibody or antibodies will bind to the appropriate antibody molecule on the bead. The particles or beads are then washed to remove any unbound DNA-oligomer-mimics and are then immobilized or trapped. The bead-antibody complexes are then exposed to a test solution which may contain the targeted antigens. If the antigen is present it will replace the mimic since it has a greater affinity for the respective antibody. The particles are then removed from the solution leaving a residual solution. This residual solution is applied a DNA chip containing many samples of complimentary DNA. If the DNA tag from a mimic binds with its complimentary DNA, it indicates the presence of the target antigen. A flourescent tag can be used to more easily identify the bound DNA tag.

  7. 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.

  8. MACHO (MAssive Compact Halo Objects) Data

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

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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Parallel path aspects of transmission modeling

    SciTech Connect (OSTI)

    Kavicky, J.A. [Argonne National Lab., IL (United States); Shahidehpour, S.M. [Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Electrical and Computer Engineering

    1996-11-01T23:59:59.000Z

    This paper examines the present methods and modeling techniques available to address the effects of parallel flows resulting from various firm and short-term energy transactions. A survey of significant methodologies is conducted to determine the present status of parallel flow transaction modeling. The strengths and weaknesses of these approaches are identified to suggest areas of further modeling improvements. The motivating force behind this research is to improve transfer capability assessment accuracy by suggesting a real-time modeling environment that adequately represents the influences of parallel flows while recognizing operational constraints and objectives.

  15. 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

  16. 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 ...

  17. 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 ...

  18. Massively Parallel Polymerase Cloning and Genome Sequencing of Single Cells Using the Microwell Displacement Amplification System (MIDAS) /

    E-Print Network [OSTI]

    Gole, Jeffrey

    2013-01-01T23:59:59.000Z

    P.C. & Quake, S.R. Digital MDA for enumeration of totalneutralization buffer and MDA master mix were each added tomicroscope using a real-time MDA system. Microwells showing

  19. 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, and Industrial Affiliates. air­bag sensor is commercially available [1]; video pro­ jections using an integrated

  20. 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

    . The vortex shed from the bubble, convects downstream and interacts with the trailing edge vortices increasing the turbulence intensity. On the suction side, dominant hairpin structures near the transitional and turbulent flow regime are observed...

  1. Massively Parallel Polymerase Cloning and Genome Sequencing of Single Cells Using the Microwell Displacement Amplification System (MIDAS) /

    E-Print Network [OSTI]

    Gole, Jeffrey

    2013-01-01T23:59:59.000Z

    genome using default Bowtie 52 parameters with removal ofmapped to the genome using Bowtie. Clonal reads resultinggenome using default Bowtie 52 parameters with removal of

  2. 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...

  3. 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...

  4. 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...

  5. An efficient parallelization scheme for molecular dynamics simulations...

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

    efficient parallelization scheme for molecular dynamics simulations with many-body, flexible, polarizable empirical An efficient parallelization scheme for molecular dynamics...

  6. 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 ...

  7. Mastery and the mobile future of massively multiplayer games

    E-Print Network [OSTI]

    Roy, Daniel, S.M. Massachusetts Institute of Technology

    2007-01-01T23:59:59.000Z

    What game design opportunities do we create when we extend massively multiplayer online games (MMOs) to cell phones? MMOs allow us to create representations of our own increasing mastery, and mobile gives us better access ...

  8. Secondary ion emission from single massive gold cluster impacts

    E-Print Network [OSTI]

    Hager, George Joseph

    2007-09-17T23:59:59.000Z

    massive projectile impacts. Secondary ion yield enhancements, resulting from use of the multi-anode detector, are reported along with secondary ion distributions for organic and inorganic targets. Au-adduct ions have been observed in mass spectra resulting...

  9. 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).

  10. 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

  11. 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...

  12. Speculative Parallelization of Sequential Loops on Multicores

    E-Print Network [OSTI]

    Tian, Chen; Feng, Min; Nagarajan, Vijay; Gupta, Rajiv

    2009-01-01T23:59:59.000Z

    le Bayes Simulator input Kmeans n2048-d16-c16 Labyrinth x32-and they include bayes, kmeans, Int J Parallel Prog (2009)535 Execution Speedup bayes kmeans labyrinth vacation yada

  13. Optimization Online - An inexact parallel splitting augmented ...

    E-Print Network [OSTI]

    Zheng Peng

    2009-06-05T23:59:59.000Z

    Jun 5, 2009 ... Abstract: Parallel iterative methods are power tool for solving large system of ... results are all most concentred to sparse system or others particular structure, and ... SOR, and AOR methods e±ciently on multiprcessor systems.

  14. 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

  15. 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

  16. A Parallel Graph Partitioner for STAPL 

    E-Print Network [OSTI]

    Castet, Nicolas

    2013-04-26T23:59:59.000Z

    Multi-core architectures are present throughout a large selection of computing devices from cell phones to super-computers. Parallel applications running on these devices solve bigger problems in a shorter time. Writing those applications is a...

  17. Gluon Radiation off Massive Quarks in a QCD Medium

    E-Print Network [OSTI]

    N. Armesto; C. A. Salgado; U. A. Wiedemann

    2004-05-19T23:59:59.000Z

    Medium-induced gluon radiation from massless and massive quarks is treated in the same formalism. The dead cone which regulates gluon radiation from massive quarks in the vacuum at small angles, is filled in the medium but constitutes a small fraction of the available phase space. Our study indicates that the energy loss for charmed hadrons at RHIC should be smaller than for light hadrons, but still sizable.

  18. 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.

  19. Reconstructing the massive black hole cosmic history through gravitational waves

    E-Print Network [OSTI]

    Alberto Sesana; Jonathan R. Gair; Emanuele Berti; Marta Volonteri

    2010-11-25T23:59:59.000Z

    The massive black holes we observe in galaxies today are the natural end-product of a complex evolutionary path, in which black holes seeded in proto-galaxies at high redshift grow through cosmic history via a sequence of mergers and accretion episodes. Electromagnetic observations probe a small subset of the population of massive black holes (namely, those that are active or those that are very close to us), but planned space-based gravitational-wave observatories such as the Laser Interferometer Space Antenna (LISA) can measure the parameters of ``electromagnetically invisible'' massive black holes out to high redshift. In this paper we introduce a Bayesian framework to analyze the information that can be gathered from a set of such measurements. Our goal is to connect a set of massive black hole binary merger observations to the underlying model of massive black hole formation. In other words, given a set of observed massive black hole coalescences, we assess what information can be extracted about the underlying massive black hole population model. For concreteness we consider ten specific models of massive black hole formation, chosen to probe four important (and largely unconstrained) aspects of the input physics used in structure formation simulations: seed formation, metallicity ``feedback'', accretion efficiency and accretion geometry. For the first time we allow for the possibility of ``model mixing'', by drawing the observed population from some combination of the ``pure'' models that have been simulated. A Bayesian analysis allows us to recover a posterior probability distribution for the ``mixing parameters'' that characterize the fractions of each model represented in the observed distribution. Our work shows that LISA has enormous potential to probe the underlying physics of structure formation.

  20. 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.

  1. Honeywell/Capstone Parallel Stand-alone Tests Honeywell/Capstone Parallel Tests

    E-Print Network [OSTI]

    Appendix H Honeywell/Capstone Parallel Stand-alone Tests 6/20/2001 #12;Honeywell/Capstone Parallel3Ø (VAR) Honeywell power Capstone Derived Power Figure H-1: Ramp Up Load Bank Power and Start Grid and Shaft Speed #12;Honeywell/Capstone Parallel Tests 6/20/2001 -10,000 0 10,000 20,000 30,000 40,000 50

  2. Parallel phase model : a programming model for high-end parallel machines with manycores.

    SciTech Connect (OSTI)

    Wu, Junfeng (Syracuse University, Syracuse, NY); Wen, Zhaofang; Heroux, Michael Allen; Brightwell, Ronald Brian

    2009-04-01T23:59:59.000Z

    This paper presents a parallel programming model, Parallel Phase Model (PPM), for next-generation high-end parallel machines based on a distributed memory architecture consisting of a networked cluster of nodes with a large number of cores on each node. PPM has a unified high-level programming abstraction that facilitates the design and implementation of parallel algorithms to exploit both the parallelism of the many cores and the parallelism at the cluster level. The programming abstraction will be suitable for expressing both fine-grained and coarse-grained parallelism. It includes a few high-level parallel programming language constructs that can be added as an extension to an existing (sequential or parallel) programming language such as C; and the implementation of PPM also includes a light-weight runtime library that runs on top of an existing network communication software layer (e.g. MPI). Design philosophy of PPM and details of the programming abstraction are also presented. Several unstructured applications that inherently require high-volume random fine-grained data accesses have been implemented in PPM with very promising results.

  3. Massive Gas Injection Experiments at JET – Performance and Characterisation of the Disruption Mitigation Valve

    E-Print Network [OSTI]

    Massive Gas Injection Experiments at JET – Performance and Characterisation of the Disruption Mitigation Valve

  4. 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

  5. Some computational challenges of developing efficient parallel algorithms for data-dependent computations in thermal-hydraulics supercomputer applications

    SciTech Connect (OSTI)

    Woodruff, S.B.

    1992-01-01T23:59:59.000Z

    The Transient Reactor Analysis Code (TRAC), which features a two- fluid treatment of thermal-hydraulics, is designed to model transients in water reactors and related facilities. One of the major computational costs associated with TRAC and similar codes is calculating constitutive coefficients. Although the formulations for these coefficients are local the costs are flow-regime- or data-dependent; i.e., the computations needed for a given spatial node often vary widely as a function of time. Consequently, poor load balancing will degrade efficiency on either vector or data parallel architectures when the data are organized according to spatial location. Unfortunately, a general automatic solution to the load-balancing problem associated with data-dependent computations is not yet available for massively parallel architectures. This document discusses why developers algorithms, such as a neural net representation, that do not exhibit algorithms, such as a neural net representation, that do not exhibit load-balancing problems.

  6. Some computational challenges of developing efficient parallel algorithms for data-dependent computations in thermal-hydraulics supercomputer applications

    SciTech Connect (OSTI)

    Woodruff, S.B.

    1992-05-01T23:59:59.000Z

    The Transient Reactor Analysis Code (TRAC), which features a two- fluid treatment of thermal-hydraulics, is designed to model transients in water reactors and related facilities. One of the major computational costs associated with TRAC and similar codes is calculating constitutive coefficients. Although the formulations for these coefficients are local the costs are flow-regime- or data-dependent; i.e., the computations needed for a given spatial node often vary widely as a function of time. Consequently, poor load balancing will degrade efficiency on either vector or data parallel architectures when the data are organized according to spatial location. Unfortunately, a general automatic solution to the load-balancing problem associated with data-dependent computations is not yet available for massively parallel architectures. This document discusses why developers algorithms, such as a neural net representation, that do not exhibit algorithms, such as a neural net representation, that do not exhibit load-balancing problems.

  7. Parallel Computer Technology -A Solution for Automobiles? How car engineers can learn from parallel computing

    E-Print Network [OSTI]

    Zachmann, Gabriel

    Parallel Computer Technology - A Solution for Automobiles? How car engineers can learn from be improved by the adoption of well known parallel computing technologies. II. HISTORY OF CAR ELECTRONICS electronics in the past. The following Table I shows the history of the car- electronics since 1950 in note

  8. Computing Permutations with Double-Ended Queues, Parallel Stacks and Parallel Queues

    E-Print Network [OSTI]

    Billey, Sara

    Computing Permutations with Double-Ended Queues, Parallel Stacks and Parallel Queues Vaughan R on edge f closest to vertex v (thereby displacing the previous closest to v on f, if any, and possibly at Stanford; by the IBM T.J.Watson Research Center, Yorktown Heights, N.Y.; and by Project MAC, an MIT

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Simulating Billion-Task Parallel Programs

    SciTech Connect (OSTI)

    Perumalla, Kalyan S [ORNL] [ORNL; Park, Alfred J [ORNL] [ORNL

    2014-01-01T23:59:59.000Z

    In simulating large parallel systems, bottom-up approaches exercise detailed hardware models with effects from simplified software models or traces, whereas top-down approaches evaluate the timing and functionality of detailed software models over coarse hardware models. Here, we focus on the top-down approach and significantly advance the scale of the simulated parallel programs. Via the direct execution technique combined with parallel discrete event simulation, we stretch the limits of the top-down approach by simulating message passing interface (MPI) programs with millions of tasks. Using a timing-validated benchmark application, a proof-of-concept scaling level is achieved to over 0.22 billion virtual MPI processes on 216,000 cores of a Cray XT5 supercomputer, representing one of the largest direct execution simulations to date, combined with a multiplexing ratio of 1024 simulated tasks per real task.

  15. 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.

  16. Parallel hybrid textures of lepton mass matrices

    E-Print Network [OSTI]

    S. Dev; Shivani Gupta; Radha Raman Gautam

    2010-09-28T23:59:59.000Z

    We analyse the parallel hybrid texture structures in the charged lepton and the neutrino sector. These parallel hybrid texture structures have physical implications as they cannot be obtained from arbitrary lepton mass matrices through weak basis transformations. The total sixty parallel hybrid texture structures can be grouped into twelve classes, and all the hybrid textures in the same class have identical physical implications. We examine all the twelve classes under the assumption of non-factorizable phases in the neutrino mass matrix. Five out of the total twelve classes are found to be phenomenologically disallowed. We study the phenomenological implications of the allowed classes for 1-3 mixing angle, Majorana and Dirac-type $CP$ violating phases. Interesting constraints on effective Majorana mass are obtained for all the allowed classes.

  17. Parallel hybrid textures of lepton mass matrices

    SciTech Connect (OSTI)

    Dev, S.; Gupta, Shivani; Gautam, Radha Raman [Department of Physics, Himachal Pradesh University, Shimla 171005 (India)

    2010-10-01T23:59:59.000Z

    We analyze the parallel hybrid texture structures in the charged lepton and the neutrino sector. These parallel hybrid texture structures have physical implications as they cannot be obtained from arbitrary lepton mass matrices through weak basis transformations. The total 60 parallel hybrid texture structures can be grouped into 12 classes, and all the hybrid textures in the same class have identical physical implications. We examine all 12 classes under the assumption of nonfactorizable phases in the neutrino mass matrix. Five out of the total 12 classes are found to be phenomenologically disallowed. We study the phenomenological implications of the allowed classes for 1-3 mixing angle, Majorana and Dirac-type CP violating phases. Interesting constraints on effective Majorana mass are obtained for all the allowed classes.

  18. Parallel hybrid textures of lepton mass matrices

    E-Print Network [OSTI]

    Dev, S; Gautam, Radha Raman

    2010-01-01T23:59:59.000Z

    We analyse the parallel hybrid texture structures in the charged lepton and the neutrino sector. These parallel hybrid texture structures have physical implications as they cannot be obtained from arbitrary lepton mass matrices through weak basis transformations. The total sixty parallel hybrid texture structures can be grouped into twelve classes, and all the hybrid textures in the same class have identical physical implications. We examine all the twelve classes under the assumption of non-factorizable phases in the neutrino mass matrix. Five out of the total twelve classes are found to be phenomenologically disallowed. We study the phenomenological implications of the allowed classes for 1-3 mixing angle, Majorana and Dirac-type $CP$ violating phases. Interesting constraints on effective Majorana mass are obtained for all the allowed classes.

  19. 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.

  20. Massive "spin-2" theories in arbitrary $D \\ge 3$ dimensions

    E-Print Network [OSTI]

    D. Dalmazi; A. L. R. dos Santos; E. L. Mendonça

    2014-08-28T23:59:59.000Z

    Here we show that in arbitrary dimensions $D\\ge 3$ there are two families of second order Lagrangians describing massive "spin-2" particles via a nonsymmetric rank-2 tensor. They differ from the usual Fierz-Pauli theory in general. At zero mass one of the families is Weyl invariant. Such massless theory has no particle content in $D=3$ and gives rise, via master action, to a dual higher order (in derivatives) description of massive spin-2 particles in $D=3$ where both the second and the fourth order terms are Weyl invariant, contrary to the linearized New Massive Gravity. However, only the fourth order term is invariant under arbitrary antisymmetric shifts. Consequently, the antisymmetric part of the tensor $e_{[\\mu\

  1. 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.

  2. Extremely Compact Massive Galaxies at 1.7

    E-Print Network [OSTI]

    Fernando Buitrago; Ignacio Trujillo; Christopher J. Conselice

    2008-11-18T23:59:59.000Z

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

  3. 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.

  4. 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.

  5. Gauge Theory of Gravity Requires Massive Torsion Field

    E-Print Network [OSTI]

    Rainer W. Kuhne

    1998-06-04T23:59:59.000Z

    One of the greatest unsolved issues of the physics of this century is to find a quantum field theory of gravity. According to a vast amount of literature unification of quantum field theory and gravitation requires a gauge theory of gravity which includes torsion and an associated spin field. Various models including either massive or massless torsion fields have been suggested. We present arguments for a massive torsion field, where the probable rest mass of the corresponding spin three gauge boson is the Planck mass.

  6. 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.

  7. Spectrophotometry of massive star forming regions with GTC

    E-Print Network [OSTI]

    M. Castellanos; A. I. Diaz; E. Terlevich

    2002-05-07T23:59:59.000Z

    In these latest years, the detection of Wolf-Rayet (WR) stars in Giant HII Regions (GHRs) has yielded several questions about our current understanding of massive stars evolution and hot expanding atmospheres, the age of the ionizing populations and their impact onto the physical properties of GHRs. Here, we present spectrophotometric observations of 4 extragalactic GHRs which show WR features in their spectra. Our goal is to reproduce simultaneously the observed WR properties and the emission line spectra with the help of current evolutionary synthesis models. Finally, we address the main advantages that GTC will provide to our better understanding of massive star forming regions.

  8. Effecting Parallel Graph Eigensolvers Through Library Composition

    E-Print Network [OSTI]

    Lumsdaine, Andrew

    is not possible in general. Conventional linear algebra libraries cannot operate on graph data types. Likewise exploitation of this duality. Graph libraries and matrix libraries use different data types, and despiteEffecting Parallel Graph Eigensolvers Through Library Composition Alex Breuer, Peter Gottschling

  9. 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.

  10. 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.

  11. Parallel Implementation of multipole-based

    E-Print Network [OSTI]

    California at Berkeley, University of

    Parallel Implementation of multipole-based Poisson-Boltzmann solver Eng Hui Yap CS 267 Project May sphere ki: 1. Calculate surface charge multipole Snm (i) Express in and out in terms of multipoles (ii. Repeat for all spheres until convergence criteria is reached Solving LPBE with Multipole Method

  12. (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

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

    E-Print Network [OSTI]

    Petrank, Erez

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

  14. PARALLEL ALGORITHM DESIGN FOR BRANCH AND BOUND

    E-Print Network [OSTI]

    Bader, David A.

    Chapter 5 PARALLEL ALGORITHM DESIGN FOR BRANCH AND BOUND David A. Bader Department of Electrical & Computer Engineering, University of New Mexico dbader@ece.unm.edu William E. Hart Discrete Mathematics communication net- work enables synchronous inter-processor communication. Grid com- pute platforms exemplify

  15. 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

  16. Automatic Loop Parallelization via Compiler Guided Refactoring

    E-Print Network [OSTI]

    . Lyngby, Denmark Email: {pl,ska}@imm.dtu.dk Computer Science Engineering Chalmers U. Technology, 412 96 by the computing industry today. Yet, applications are often written in ways that prevent automatic parallelization Gothenburg, Sweden Email: lidman@student.chalmers.se, mckee@chalmers.se IBM Haifa Research Labs Mount Carmel

  17. Titanium and Java Parallelism Arvind Krishnamurthy

    E-Print Network [OSTI]

    Krishnamurthy, Arvind

    1 Titanium and Java Parallelism Arvind Krishnamurthy Fall 2004 Titanium Take the best features: checked at compile time, no unsafe casts Automatic memory management Titanium is (almost) strict superset VisComplex extends Complex { ... } Immutable Classes in Titanium For small objects, would sometimes

  18. WEBPIE: A WEB-SCALE PARALLEL INFERENCE

    E-Print Network [OSTI]

    WEBPIE: A WEB-SCALE PARALLEL INFERENCE ENGINE Jacopo Urbani, Spyros Kotoulas, Jason Maassen, Niels Amsterdam Monday 10 May 2010 #12;The Semantic Web The Semantic Web is an extension of the current Web where the semantics is defined Basically the idea is to move from Web of Documents (Traditional Web) Web of data

  19. Parallelism for quantum computation with qudits

    SciTech Connect (OSTI)

    O'Leary, Dianne P. [Department of Computer Science and Institute for Advanced Computer Studies, University of Maryland, College Park, Maryland 20742, USA and Mathematical and Computational Sciences Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); IDA Center for Computing Sciences, 17100 Science Drive, Bowie, Maryland 20715-4300 (United States); Brennen, Gavin K. [Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020, Innsbruck (Austria); Bullock, Stephen S. [IDA Center for Computing Sciences, 17100 Science Drive, Bowie, Maryland 20715-4300 (United States)

    2006-09-15T23:59:59.000Z

    Robust quantum computation with d-level quantum systems (qudits) poses two requirements: fast, parallel quantum gates and high-fidelity two-qudit gates. We first describe how to implement parallel single-qudit operations. It is by now well known that any single-qudit unitary can be decomposed into a sequence of Givens rotations on two-dimensional subspaces of the qudit state space. Using a coupling graph to represent physically allowed couplings between pairs of qudit states, we then show that the logical depth (time) of the parallel gate sequence is equal to the height of an associated tree. The implementation of a given unitary can then optimize the tradeoff between gate time and resources used. These ideas are illustrated for qudits encoded in the ground hyperfine states of the alkali-metal atoms {sup 87}Rb and {sup 133}Cs. Second, we provide a protocol for implementing parallelized nonlocal two-qudit gates using the assistance of entangled qubit pairs. Using known protocols for qubit entanglement purification, this offers the possibility of high-fidelity two-qudit gates.

  20. 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

  1. 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.

  2. 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.

  3. VIP-FS: A Virtual, Parallel file System for High Performance Parallel and Distributed Computing *

    E-Print Network [OSTI]

    Kuzmanovic, Aleksandar

    -passing li- blclries only provide part of the support necessary for most high performan.ce distributed computing applzca- tzcjns - support for hagh speed parallel l/O is still lark- 211q. In this paper, we

  4. 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

  5. MICROGRIDS -The Exploitation of Massive On-chip Concurrency

    E-Print Network [OSTI]

    Jesshope, Chris

    MICROGRIDS - The Exploitation of Massive On-chip Concurrency C. R. Jesshope Department of Computer not yield concurrency unless existing code is recompiled using the concurrency controls introduced be explicitly programmed and is at a relatively coarse grain. An ideal architecture would provide this same

  6. 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

  7. Glacier: Highly durable, decentralized storage despite massive correlated failures

    E-Print Network [OSTI]

    Pennsylvania, University of

    Glacier: Highly durable, decentralized storage despite massive correlated failures Andreas be considered when attempting to provide highly durable storage. In this paper, we describe Glacier failures. Glacier is designed to aggressively minimize the cost of this redun- dancy in space and time

  8. 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.

  9. Improved Magnetic Fusion Energy Economics Via Massive Resistive Electromagnets

    E-Print Network [OSTI]

    for cryogenic refrigeration plants needed to maintain the magnets' temperature near absolute zero, direct costsImproved Magnetic Fusion Energy Economics Via Massive Resistive Electromagnets Robert D. Woolley for magnetic fusion reactors and instead using resistive magnet designs based on cheap copper or aluminum

  10. Massive main sequence stars evolving at the Eddington limit

    E-Print Network [OSTI]

    Sanyal, Debashis; Langer, Norbert; Bestenlehner, Joachim M

    2015-01-01T23:59:59.000Z

    The evolution of massive stars even on the main sequence is not yet well understood. Due to the steep mass-luminosity relation, massive main sequence stars become very luminous. This brings their envelopes very close to the Eddington limit. We are analysing stellar evolutionary models in which the Eddington limit is reached and exceeded, and explore the rich diversity of physical phenomena which take place in their envelopes, and investigate their observational consequences. We use the grids of detailed stellar models by Brott et al. (2011) and Koehler et al. (2015), to investigate the envelope properties of core hydrogen burning massive stars. We find that at the stellar surface, the Eddington limit is almost never reached, even for stars up to 500 Msun. When an appropriate Eddington limit is defined locally in the stellar envelope, most stars more massive than 40 Msun actually exceed this limit, in particular in the partial ionization zones of iron, helium or hydrogen. While most models adjust their structu...

  11. Massive Pellet and Rupture Disk Testing for Disruption Mitigation Applications

    SciTech Connect (OSTI)

    Combs, Stephen Kirk [ORNL] [ORNL; Meitner, Steven J [ORNL] [ORNL; Baylor, Larry R [ORNL] [ORNL; Caughman, John B [ORNL] [ORNL; Commaux, Nicolas JC [ORNL] [ORNL; Fehling, Dan T [ORNL] [ORNL; Foust, Charles R [ORNL] [ORNL; Jernigan, Thomas C [ORNL] [ORNL; McGill, James M [ORNL] [ORNL; Parks, P. B. [General Atomics] [General Atomics; Rasmussen, David A [ORNL] [ORNL

    2009-01-01T23:59:59.000Z

    Injection of massive quantities of noble gases or D2 has proven to be effective at mitigating some of the deleterious effects of disruptions in tokamaks. Two alternative methods that might offer some advantages over the present technique for massive gas injection are shattering massive pellets and employing close-coupled rupture disks. Laboratory testing has been carried out to evaluate their feasibility. For the study of massive pellets, a pipe gun pellet injector cooled with a cryogenic refrigerator was fitted with a relatively large barrel (16.5 mm bore), and D2 and Ne pellets were made and were accelerated to speeds of ~600 and 300 m/s, respectively. Based on the successful proof-of-principle testing with the injector and a special double-impact target to shatter pellets, a similar system has been prepared and installed on DIII-D and should be ready for experiments later this year. To study the applicability of rupture disks for disruption mitigation, a simple test apparatus was assembled in the lab. Commercially available rupture disks of 1 in. nominal diameter were tested at conditions relevant for the application on tokamaks, including tests with Ar and He gases and rupture pressures of ~54 bar. Some technical and practical issues of implementing this technique on a tokamak are discussed.

  12. Parallel Algorithms for Time and Frequency Domain Circuit Simulation

    E-Print Network [OSTI]

    Dong, Wei

    2010-10-12T23:59:59.000Z

    parallelization due to its explicit nature. For frequency-domain simulation, this dissertation presents a parallel harmonic balance approach, applicable to the steady-state and envelope-following analyses of both driven and autonomous circuits. The new approach...

  13. 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 ...

  14. 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

  15. 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

  16. 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

  17. 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 ...

  18. 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

  19. 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.

  20. Kalman Filter Tracking on Parallel Architectures

    E-Print Network [OSTI]

    Cerati, Giuseppe; Lantz, Steven; McDermott, Kevin; Riley, Dan; Tadel, Matevž; Wittich, Peter; Würthwein, Frank; Yagil, Avi

    2015-01-01T23:59:59.000Z

    Power density constraints are limiting the performance improvements of modern CPUs. To address this we have seen the introduction of lower-power, multi-core processors, but the future will be even more exciting. In order to stay within the power density limits but still obtain Moore's Law performance/price gains, it will be necessary to parallelize algorithms to exploit larger numbers of lightweight cores and specialized functions like large vector units. Example technologies today include Intel's Xeon Phi and GPGPUs. Track finding and fitting is one of the most computationally challenging problems for event reconstruction in particle physics. At the High Luminosity LHC, for example, this will be by far the dominant problem. The need for greater parallelism has driven investigations of very different track finding techniques including Cellular Automata or returning to Hough Transform. The most common track finding techniques in use today are however those based on the Kalman Filter. Significant experience has...

  1. Parallel State Estimation Assessment with Practical Data

    SciTech Connect (OSTI)

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

    2013-07-31T23:59:59.000Z

    This paper presents a parallel state estimation (PSE) implementation using a preconditioned gradient algorithm and an orthogonal decomposition-based algorithm. The preliminary tests against a commercial Energy Management System (EMS) State Estimation (SE) tool using real-world data are performed. The results show that while the precondition gradient algorithm can solve the SE problem quicker with the help of parallel computing techniques, it might not be good for real-world data due to the large condition number of gain matrix introduced by the wide range of measurement weights. With the help of PETSc package and considering one iteration of the SE process, the orthogonal decomposition-based PSE algorithm can achieve 5-20 times speedup comparing against the commercial EMS tool. It is very promising that the developed PSE can solve the SE problem for large power systems at the SCADA rate, to improve grid reliability.

  2. 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.

  3. 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.

  4. 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.

  5. Parallel revised simplex for primal block angular LP problems

    E-Print Network [OSTI]

    Hall, Julian

    Parallel revised simplex for primal block angular LP problems Julian Hall and Edmund Smith School) problems and their identification Computational components of the revised simplex method Exploiting parallelism via BALP structure Results Observations J. A. J. Hall and E. Smith Parallel revised simplex

  6. Update procedures for the parallel revised simplex method

    E-Print Network [OSTI]

    Hall, Julian

    Update procedures for the parallel revised simplex method J. A. J. Hall and K. I. M. McKinnon 30th #12;Update procedures for the parallel revised simplex method J. A. J. Hall K. I. M. McKinnon 30th September 1992 Abstract In the parallel revised simplex method proposed by Hall et al. in 8], the inversion

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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

  13. 32 TaskSpaces: A Software Framework for Parallel

    E-Print Network [OSTI]

    De Sterck, Hans

    and Computational Biology, A. Zomaya, editor, John Wiley and Sons, 2005. i #12;Contents 32 Parallel Bioinformatics32 TaskSpaces: A Software Framework for Parallel Bioinformatics on Computational Grids HANS DE, there is a natural drive towards applying parallel and distributed computing to bioinformatics problems. Grid

  14. Stochastic Particle Acceleration in Parallel Relativistic Shocks

    E-Print Network [OSTI]

    Joni J. P. Virtanen; Rami Vainio

    2005-03-03T23:59:59.000Z

    We present results of test-particle simulations on both the first- and the second-order Fermi acceleration for relativistic parallel shock waves. Our studies suggest that the role of the second-order mechanism in the turbulent downstream of a relativistic shock may have been underestimated in the past, and that the stochastic mechanism may have significant effects on the form of the particle spectra and its time evolution.

  15. Parallel implementation of sparse matrix solvers

    E-Print Network [OSTI]

    Pujari, Sushant Kumar

    1992-01-01T23:59:59.000Z

    faster, utilizing its sparseness and adaptibility to parallel architecture, is of practical significance. It was observed that the sparse solvers used in this work are very efficient in solving sparse matrices, in fact a significant reduction... Performance results for Harwell sparse solver. 25 Performance of Yale's solver for matrices of various sizes, with 50% spar- sity, on different architecture. 27 IV Performance of Harwell so! ver for matrices of various sizes, with 50% spar- sity...

  16. Kalman Filter Tracking on Parallel Architectures

    E-Print Network [OSTI]

    Giuseppe Cerati; Peter Elmer; Steven Lantz; Kevin McDermott; Dan Riley; Matevž Tadel; Peter Wittich; Frank Würthwein; Avi Yagil

    2015-05-18T23:59:59.000Z

    Power density constraints are limiting the performance improvements of modern CPUs. To address this we have seen the introduction of lower-power, multi-core processors, but the future will be even more exciting. In order to stay within the power density limits but still obtain Moore's Law performance/price gains, it will be necessary to parallelize algorithms to exploit larger numbers of lightweight cores and specialized functions like large vector units. Example technologies today include Intel's Xeon Phi and GPGPUs. Track finding and fitting is one of the most computationally challenging problems for event reconstruction in particle physics. At the High Luminosity LHC, for example, this will be by far the dominant problem. The need for greater parallelism has driven investigations of very different track finding techniques including Cellular Automata or returning to Hough Transform. The most common track finding techniques in use today are however those based on the Kalman Filter. Significant experience has been accumulated with these techniques on real tracking detector systems, both in the trigger and offline. They are known to provide high physics performance, are robust and are exactly those being used today for the design of the tracking system for HL-LHC. Our previous investigations showed that, using optimized data structures, track fitting with Kalman Filter can achieve large speedup both with Intel Xeon and Xeon Phi. We report here our further progress towards an end-to-end track reconstruction algorithm fully exploiting vectorization and parallelization techniques in a realistic simulation setup.

  17. Intelligent spatial ecosystem modeling using parallel processors

    SciTech Connect (OSTI)

    Maxwell, T.; Costanza, R. (Maryland International Inst. for Ecological Economics, Solomons (United States))

    1993-05-01T23:59:59.000Z

    Spatial modeling of ecosystems is essential if one's modeling goals include developing a relatively realistic description of past behavior and predictions of the impacts of alternative management policies on future ecosystem behavior. Development of these models has been limited in the past by the large amount of input data required and the difficulty of even large mainframe serial computers in dealing with large spatial arrays. These two limitations have begun to erode with the increasing availability of remote sensing data and GIS systems to manipulate it, and the development of parallel computer systems which allow computation of large, complex, spatial arrays. Although many forms of dynamic spatial modeling are highly amenable to parallel processing, the primary focus in this project is on process-based landscape models. These models simulate spatial structure by first compartmentalizing the landscape into some geometric design and then describing flows within compartments and spatial processes between compartments according to location-specific algorithms. The authors are currently building and running parallel spatial models at the regional scale for the Patuxent River region in Maryland, the Everglades in Florida, and Barataria Basin in Louisiana. The authors are also planning a project to construct a series of spatially explicit linked ecological and economic simulation models aimed at assessing the long-term potential impacts of global climate change.

  18. 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.

  19. 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

  20. Parallel Dimers and Anti-parallel Tetramers Formed by Epidermal Growth Factor Receptor Pathway Substrate Clone 15 (EPS15)*

    E-Print Network [OSTI]

    Kirchhausen, Tomas

    Parallel Dimers and Anti-parallel Tetramers Formed by Epidermal Growth Factor Receptor Pathway- dependent endocytic traffic. We report here that Eps15 forms dimers and tetramers of distinct shape. The Eps tetramer has a "dumbbell" shape, 31 nm in length; it is formed by the anti-parallel association of two Eps

  1. 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.

  2. High energy gamma-rays from massive binary systems

    E-Print Network [OSTI]

    W. Bednarek

    2008-06-27T23:59:59.000Z

    During last years a few massive binary systems have been detected in the TeV gamma-rays. This gamma-ray emission is clearly modulated with the orbital periods of these binaries suggesting its origin inside the binary system. In this paper we summarize the anisotropic IC e-p pair cascade model as likely explanation of these observations. We consider scenarios in which particles are accelerated to relativistic energies, either due to the presence of an energetic pulsar inside the binary, or as a result of accretion process onto the compact object during which the jet is launched from the inner part of the accretion disk, or in collisions of stellar winds from the massive companions.

  3. Giant black hole ringings induced by massive gravity

    E-Print Network [OSTI]

    Yves Decanini; Antoine Folacci; Mohamed Ould El Hadj

    2014-01-01T23:59:59.000Z

    A distorted black hole radiates gravitational waves in order to settle down in one of the geometries permitted by the no-hair theorem. During that relaxation phase, a characteristic damped ringing is generated. It can be theoretically constructed from the black hole quasinormal frequencies (which govern its oscillating behavior and its decay) and from the associated excitation factors (which determine intrinsically its amplitude) by carefully taking into account the source of the distortion. Here, by considering the Schwarzschild black hole in the framework of massive gravity, we show that the excitation factors have an unexpected strong resonant behavior leading to giant ringings which are, moreover, slowly decaying. Such extraordinary black hole ringings could be observed by the next generations of gravitational wave detectors and allow us to test the various massive gravity theories or their absence could be used to impose strong constraints on the graviton mass.

  4. 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.

  5. A symmetric approach to the massive nonlinear sigma model

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

    Ferrari, Ruggero [Univ. of Milano, and INFN, Milan (Italy)

    2011-01-01T23:59:59.000Z

    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.

  6. 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.

  7. 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

  8. 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.

  9. Heterotic p-branes from Massive Sigma Models

    E-Print Network [OSTI]

    N. D. Lambert

    1996-07-11T23:59:59.000Z

    We explicitly construct massive (0,4) supersymmetric ADHM sigma models which have heterotic p-brane solitons as their conformal fixed points. These yield the familiar gauge 5-brane and a new 1-brane solution which preserve 1/2 and 1/4 of the spacetime supersymmetry respectively. We also discuss an analogous construction for the type II NS-NS p-branes using (4,4) supersymmetric models.

  10. 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...

  11. 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.

  12. 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.

  13. Massive stars vs. nebular abundances in the Orion nebula

    E-Print Network [OSTI]

    Sergio Simón Díaz

    2006-11-16T23:59:59.000Z

    The search of consistency between nebular and massive star abundances has been a longstanding problem. I briefly review what has been done regarding to this topic, also presenting a recent study focused on the Orion nebula: the O and Si stellar abundances resulting from a detailed and fully consistent spectroscopic analysis of the group of B stars associated with the Orion nebula are compared with the most recent nebular gas-phase results.

  14. 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.

  15. 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...

  16. 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...

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. Efficient Parallel Text Compression on GPUs

    E-Print Network [OSTI]

    Zhang, Xiaoxi

    2012-02-14T23:59:59.000Z

    comparison with FreeArc (0.66) on 6x2.8 GHz core, FreeArc (0.66) on 1x2.8GHz core, winrar (4.01), winzip (15.5), gzip (1.3.12) and 7zip (9.20). . . . . . . . . . . . . . . 35 1 CHAPTER I INTRODUCTION The textual content of the Web is growing at a... run on multi-core CPU while their approach is splitting a big file to blocks 5 and then assigning them to different cores, therefore the algorithm is in fact sequen- tial. PBZIP2 [8] is a parallel Bzip implementation which is inherently feasible...

  4. Switch for serial or parallel communication networks

    DOE Patents [OSTI]

    Crosette, Dario B. (DeSoto, TX)

    1994-01-01T23:59:59.000Z

    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.

  5. 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.

  6. 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}.

  7. 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.

  8. Parallel Pruning for KMeans Clustering on Shared Memory Architectures

    E-Print Network [OSTI]

    Gursoy, Attila

    Parallel Pruning for K­Means Clustering on Shared Memory Architectures Attila G¨ursoy and â?? Ilker@cs.bilkent.edu.tr Abstract. We have developed and evaluated two parallelization schemes for a tree­based k­means clustering, but the efficiency is re­ duced due to thread synchronizations. In both cases, parallel tree­based k­means clustering

  9. 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.

  10. Repulsive gravity near naked singularities and point massive particles

    E-Print Network [OSTI]

    J. W. Maluf

    2014-05-05T23:59:59.000Z

    We investigate the existence of repulsive gravitational acceleration near naked singularities. The investigation is carried out by means of the acceleration tensor, which is a coordinate invariant object. We find that the gravitational acceleration is repulsive in the vicinity of the origin in the Reissner-Nordstr{\\o}m and in the Kerr space-times, and attractive at large distances in the expected Newtonian way. We further address the space-time of a point massive particle, which also exhibits repulsive effects near the origin.

  11. 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.

  12. A New Massive Type IIA Supergravity From Compactification

    E-Print Network [OSTI]

    P. S. Howe; N. D. Lambert; P. C. West

    1997-08-05T23:59:59.000Z

    We consider the most general form for eleven dimensional supersymmetry compatible with on-shell superfields. This allows for the introduction of a conformal Spin(1,10) connection. In eleven dimensional Minkowski space this modification is trivial and can be removed by a field redefinition, however, upon compactification on S^1 it is possible to introduce a non-trivial `Wilson line'. The resulting ten dimensional supergravity has massive 1-form and 3-form potentials and a cosmological constant. This theory does not possess a supersymmetric eightbrane soliton but it does admit a supersymmetric non-static cosmological solution.

  13. 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.

  14. 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.

  15. 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.

  16. 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 ...

  17. Optimization Online - Parallelizing the dual revised simplex method

    E-Print Network [OSTI]

    Q. Huangfu

    2015-03-06T23:59:59.000Z

    Mar 6, 2015 ... Abstract: This paper introduces the design and implementation of two parallel dual simplex solvers for general large scale sparse linear ...

  18. RESEARCH ARTICLE On the parallel solution of dense saddle ...

    E-Print Network [OSTI]

    2010-10-26T23:59:59.000Z

    Oct 15, 2010 ... generation high performance computing. By parallelizing the dense factorization, we removed the memory usage bottle- neck that prevented ...

  19. Balanced Decomposition for Power System Simulation on Parallel Computers

    E-Print Network [OSTI]

    Catholic University of Chile (Universidad Católica de Chile)

    industry and the associated academic research are requiring complex de- velopments in high performance computing tools, such as parallel computers, e cient compilers, graphic interfaces and algorithms including

  20. Optimization Online - PSMG-A Parallel Structured Model Generator ...

    E-Print Network [OSTI]

    Feng Qiang

    2014-10-10T23:59:59.000Z

    Oct 10, 2014 ... As far as we are aware, PSMG is the first processor for an algebraic modelling language that is capable of generating the problem in parallel.

  1. 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.

  2. automated parallel performance: Topics by E-print Network

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

    Next Page Last Page Topic Index 1 Motivation Measuring Speedup Parallel Out of Mem Automation Introduction to High-Performance R Mathematics Websites Summary: Motivation...

  3. 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)

  4. 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...

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Parallelism of the SANDstorm hash algorithm.

    SciTech Connect (OSTI)

    Torgerson, Mark Dolan; Draelos, Timothy John; Schroeppel, Richard Crabtree

    2009-09-01T23:59:59.000Z

    Mainstream cryptographic hashing algorithms are not parallelizable. This limits their speed and they are not able to take advantage of the current trend of being run on multi-core platforms. Being limited in speed limits their usefulness as an authentication mechanism in secure communications. Sandia researchers have created a new cryptographic hashing algorithm, SANDstorm, which was specifically designed to take advantage of multi-core processing and be parallelizable on a wide range of platforms. This report describes a late-start LDRD effort to verify the parallelizability claims of the SANDstorm designers. We have shown, with operating code and bench testing, that the SANDstorm algorithm may be trivially parallelized on a wide range of hardware platforms. Implementations using OpenMP demonstrates a linear speedup with multiple cores. We have also shown significant performance gains with optimized C code and the use of assembly instructions to exploit particular platform capabilities.

  15. 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.

  16. 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.

  17. 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.

  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. 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.

  20. 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...

  1. TeV neutrinos from microquasars in compact massive binaries

    E-Print Network [OSTI]

    W. Bednarek

    2005-05-27T23:59:59.000Z

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

  2. The metallicities of luminous, massive field galaxies at intermediate redshifts

    E-Print Network [OSTI]

    M. Mouhcine; S. P. Bamford; A. Aragon-Salamanca; O. Nakamura

    2006-03-23T23:59:59.000Z

    We derive oxygen abundances for a sample of 40 luminous (M_{B} = 0.45. Oxygen abundances, relative to hydrogen, of the interstellar emitting gas are estimated by means of the empirically calibrated strong emission line ratio technique. The derived (12+log(O/H)) values range from 8.4 to 9.0, with a median of 8.7. Twenty of these galaxies have securely measured rotation velocities, in the range 50--244 km/s. The measured emission line equivalent widths and diagnostic ratios for the intermediate redshift galaxies cover similar ranges to those observed across a large sample of local galaxies. The estimated oxygen abundances for our luminous star-forming intermediate redshift galaxies cover the same range as their local counterparts. However, at a given galaxy luminosity, many of our galaxies have significantly lower oxygen abundances, i.e., $(12+log(O/H))~8.6$, than local galaxies with similar luminosities. Interestingly, these luminous, massive, intermediate redshift, star-forming galaxies with low oxygen abundances exhibit physical conditions, i.e., emission line equivalent width and ionization state, very similar to those of local faint and metal-poor star-forming galaxies. The oxygen abundance of the interstellar gas does not seem to correlate with the maximum rotation velocity or the emission scale length of the parent galaxy. This suggests that there is a diversity in the intrinsic properties of the massive field galaxy population at intermediate redshifts (ABRIDGED).

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  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

    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.

  10. 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.

  11. Parallel visualization and analysis with paraview on a Cray XT4

    SciTech Connect (OSTI)

    Ahrens, James P [Los Alamos National Laboratory; Patchett, John M [Los Alamos National Laboratory; Pugmire, David L [ORNL; Ahern, Sean [ORNL

    2010-01-01T23:59:59.000Z

    Scientific data sets produced by modern supercomputers like ORNL's Cray XT 4, Jaguar, can be extremely large, making visualization and analysis more difficult as moving large resultant data to dedicated analysis systems can be prohibitively expensive. We share our continuing work of integrating a parallel visualization system, ParaView, on ORNL's Jaguar system and our efforts to enable extreme scale interactive data visualization and analysis. We will discuss porting challenges and present performance numbers. Jaguar is a Cray XT4 with 7,832 compute nodes each with 4 cores and 8GB of memory, located in Oak Ridge, Tennessee. Jaguar is currently ranked No.8 in the Top 500. Jaguar, and other machines like it, enable increasingly larger data sets. Whether scientists are producing extremely massive data or small data they still have a requirement for analysis. Analysis is often difficult for larger data and it is further complicated when the user is distant to the data. Data sets that are too large to ship and/or analyze on a single desktop require a parallel analysis tool and a high performance computer to run on. Running ParaView interactively on Jaguar is a positive improvement for both local and remote users. We have shown that it is feasible for our user at LANL to visualize his simulation data created on jaguar. Local users may face fewer obstacles and get improved performance, due to their higher bandwidth to Jaguar. For future work, we would like to see higher priority queues that enable interactive visualization. A more interactive user-friendly qsub that estimates time to allocation would be very useful. Hopefully, our work will lead to more users attempting interactive visualization on Jaguar, resulting in quicker turnaround times for visualization and analysis. As users migrate to using supercomputing platforms for visualization, we expect future research possibilities in this area.

  12. 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_\

  13. 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.

  14. The Parallel BGL: A Generic Library for Distributed Graph Computations

    E-Print Network [OSTI]

    Lumsdaine, Andrew

    ] and written in a style similar to the C++ Standard Template Library (STL) [38, 46], 1 #12;data types providedThe Parallel BGL: A Generic Library for Distributed Graph Computations Douglas Gregor and Andrew,lums}@osl.iu.edu Abstract This paper presents the Parallel BGL, a generic C++ library for distributed graph computation

  15. Design and Implementation of a Parallel Constraint Satisfaction Algorithm

    E-Print Network [OSTI]

    Hellebrand, Sybille

    simulator QSim. The presented parallel algorithm is based on partitioning the search space of a CSP into independent subspaces. These subspaces are then searched for solutions in parallel with a backtracking introduce a newpartitioning method, called variable-based partitioning (VBP). This method discards many

  16. 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

  17. Parallel matrix inversion for the revised simplex method -A study

    E-Print Network [OSTI]

    Hall, Julian

    Parallel matrix inversion for the revised simplex method - A study Julian Hall School of Mathematics University of Edinburgh June 15th 2006 Parallel matrix inversion for the revised simplex method - a study #12;Overview · Nature of the challenge of matrix inversion for the revised simplex method #12

  18. Parallel matrix inversion for the revised simplex method -A study

    E-Print Network [OSTI]

    Hall, Julian

    Parallel matrix inversion for the revised simplex method - A study Julian Hall School of Mathematics University of Edinburgh June 15th 2006 Parallel matrix inversion for the revised simplex method - a study #12;Overview · Nature of the challenge of matrix inversion for the revised simplex method

  19. The Effect of Communication Time Delays in Parallel Computations

    E-Print Network [OSTI]

    in the literature. Various taxonomies of load balanc- ing algorithms exist. Direct methods examine the global a shared network. To make use of parallel computing resources, problems must be broken down into smaller Indexing System (CODIS) software are candidates for parallelization. New methods developed by Wang et al

  20. architecture parallele pour: Topics by E-print Network

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

    architecture parallele pour First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 CSCE 3030: Parallel...

  1. 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 of logic levels, fanout, and wiring tracks. This paper presents a three-dimensional taxonomy that not only for wide adders. This paper develops a taxonomy of parallel prefix networks based on stages, fanout

  2. G 2 MANIFOLDS WITH PARALLEL CHARACTERISTIC TORSION THOMAS FRIEDRICH

    E-Print Network [OSTI]

    Friedrich, Thomas

    these spaces admit a metric connec­ tion # c with totally skew­symmetric torsion and a spinor field #1 solvingG 2 ­MANIFOLDS WITH PARALLEL CHARACTERISTIC TORSION THOMAS FRIEDRICH Abstract. We classify 7­dimensional cocalibrated G2­manifolds with parallel char­ acteristic torsion and non­abelian holonomy. All

  3. 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

  4. A Lightweight, Scalable Grid Computing Framework for Parallel Bioinformatics Applications

    E-Print Network [OSTI]

    De Sterck, Hans

    and methods for solving large scientific and engineering problems on such parallel and distributed computersA Lightweight, Scalable Grid Computing Framework for Parallel Bioinformatics Applications Hans De Sterck Department of Applied Mathematics University of Waterloo Waterloo, Ontario N2L 3G1, Canada Email

  5. 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

  6. 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...

  7. 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

  8. 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

  9. OSCAR Parallelizing Compiler Cooperative Heterogeneous Multi-core Architecture

    E-Print Network [OSTI]

    Kasahara, Hironori

    OSCAR Parallelizing Compiler Cooperative Heterogeneous Multi-core Architecture Akihiro Hayashi,kamiyama,watanabe,takeshi,mase}@kasahara.cs.waseda.ac.jp 1. Background Heterogeneous multi-core architectures, which integrates multiple general purpose CPU, powerful parallelizing compiler for hetero- geneous multi-core architectures is expected. Furthermore

  10. 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...

  11. Parallel optical nanolithography using nanoscale bowtie aperture array

    E-Print Network [OSTI]

    Xu, Xianfan

    Parallel optical nanolithography using nanoscale bowtie aperture array Sreemanth M.V. Uppuluri of parallel optical nanolithography using nanoscale bowtie aperture array. These nanoscale bowtie aperture1805 photoresist. An interference-based optical alignment system was employed to position the bowtie

  12. Parallel FPGA Implementation of RSA with Residue Number Systems

    E-Print Network [OSTI]

    Parallel FPGA Implementation of RSA with Residue Number Systems --- Can side­channel threats Multiplication based on Residue Num­ ber Systems. Thanks to RNS, we develop a design able to perform an RSA signature in parallel on a set of identical and independent copro­ cessors. Of independent interest, we

  13. Parallel FPGA Implementation of RSA with Residue Number Systems

    E-Print Network [OSTI]

    Parallel FPGA Implementation of RSA with Residue Number Systems -- Can side-channel threats Multiplication based on Residue Num- ber Systems. Thanks to RNS, we develop a design able to perform an RSA signature in parallel on a set of identical and independent copro- cessors. Of independent interest, we

  14. 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

  15. Parallel Kahler submanifolds of quaternionic Kahler symmetric spaces

    E-Print Network [OSTI]

    Alekseevsky, Dmiti

    is a full parallel K¨ahler submanifold of M . 2) If C = 0 then M = HPm and (M2m , J) is a Hermitian , with the canonical Tsukada imbedding into HPm as described in [Tsu2] . Thus, the classification of parallel K

  16. 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

  17. 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

  18. The VLT-FLAMES survey of massive stars: rotation and nitrogen enrichment as the key to understanding massive star evolution

    E-Print Network [OSTI]

    I. Hunter; I. Brott; D. J. Lennon; N. Langer; P. L. Dufton; C. Trundle; S. J. Smartt; A. de Koter; C. J. Evans; R. S. I. Ryans

    2008-02-18T23:59:59.000Z

    Rotation has become an important element in evolutionary models of massive stars, specifically via the prediction of rotational mixing. Here, we study a sample of stars, including rapid rotators, to constrain such models and use nitrogen enrichments as a probe of the mixing process. Chemical compositions (C, N, O, Mg and Si) have been estimated for 135 early B-type stars in the Large Magellanic Cloud with projected rotational velocities up to ~300km/s using a non-LTE TLUSTY model atmosphere grid. Evolutionary models, including rotational mixing, have been generated attempting to reproduce these observations by adjusting the overshooting and rotational mixing parameters and produce reasonable agreement with 60% of our core hydrogen burning sample. We find (excluding known binaries) a significant population of highly nitrogen enriched intrinsic slow rotators vsini less than 50km/s incompatible with our models ~20% of the sample). Furthermore, while we find fast rotators with enrichments in agreement with the models, the observation of evolved (log g less than 3.7dex) fast rotators that are relatively unenriched (a further ~20% of the sample) challenges the concept of rotational mixing. We also find that 70% of our blue supergiant sample cannot have evolved directly from the hydrogen burning main-sequence. We are left with a picture where invoking binarity and perhaps fossil magnetic fields are required to understand the surface properties of a population of massive main sequence stars.

  19. 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.

  20. 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.

  1. 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)).

  2. 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.

  3. Cooling, Gravity and Geometry: Flow-driven Massive Core Formation

    E-Print Network [OSTI]

    Fabian Heitsch; Lee Hartmann; Adrianne D. Slyz; Julien E. G. Devriendt; Andreas Burkert

    2007-09-15T23:59:59.000Z

    We study numerically the formation of molecular clouds in large-scale colliding flows including self-gravity. The models emphasize the competition between the effects of gravity on global and local scales in an isolated cloud. Global gravity builds up large-scale filaments, while local gravity -- triggered by a combination of strong thermal and dynamical instabilities -- causes cores to form. The dynamical instabilities give rise to a local focusing of the colliding flows, facilitating the rapid formation of massive protostellar cores of a few 100 M$_\\odot$. The forming clouds do not reach an equilibrium state, though the motions within the clouds appear comparable to ``virial''. The self-similar core mass distributions derived from models with and without self-gravity indicate that the core mass distribution is set very early on during the cloud formation process, predominantly by a combination of thermal and dynamical instabilities rather than by self-gravity.

  4. 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.

  5. Nanowire growth by an electron beam induced massive phase transformation

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

    Sood, Shantanu; Kisslinger, Kim; Gouma, Perena

    2014-12-01T23:59:59.000Z

    Tungsten trioxide nanowires of a high aspect ratio have been synthesized in-situ in a TEM under an electron beam of current density 14A/cm² due to a massive polymorphic reaction. Sol-gel processed pseudocubic phase nanocrystals of tungsten trioxide were seen to rapidly transform to one dimensional monoclinic phase configurations, and this reaction was independent of the substrate on which the material was deposited. The mechanism of the self-catalyzed polymorphic transition and accompanying radical shape change is a typical characteristic of metastable to stable phase transformations in nanostructured polymorphic metal oxides. A heuristic model is used to confirm the metastable to stablemore »growth mechanism. The findings are important to the control electron beam deposition of nanowires for functional applications starting from colloidal precursors.« less

  6. 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.

  7. On the Compton scattering vertex for massive scalar QED

    E-Print Network [OSTI]

    A. Bashir; Y. Concha-Sanchez; R. Delbourgo; M. E. Tejeda-Yeomans

    2009-06-23T23:59:59.000Z

    We investigate the Compton scattering vertex of charged scalars and photons in scalar quantum electrodynamics (SQED). We carry out its non perturbative construction consistent with Ward-Fradkin-Green-Takahashi identity (WFGTI) which relates 3-point vertices to the 4-point ones. There is an undetermined part which is transverse to one or both the external photons, and needs to be evaluated through perturbation theory. We present in detail how the transverse part at the 1-loop order can be evaluated for completely general kinematics of momenta involved in covariant gauges and dimensions. This involves the calculation of genuine 4-point functions with three massive propagators, the most non-trivial integrals reported in this paper. We also discuss possible applications of our results.

  8. 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.

  9. 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.

  10. Pair Instability Supernovae of Very Massive Population III Stars

    E-Print Network [OSTI]

    Chen, Ke-Jung; Woosley, Stan; Almgren, Ann; Whalen, Daniel

    2014-01-01T23:59:59.000Z

    Numerical studies of primordial star formation suggest that the first stars in the universe may have been very massive. Stellar models indicate that non-rotating Population III stars with initial masses of 140-260 Msun die as highly energetic pair-instability supernovae. We present new two-dimensional simulations of primordial pair-instability supernovae done with the CASTRO code. Our simulations begin at earlier times than previous multidimensional models, at the onset of core collapse, to capture any dynamical instabilities that may be seeded by collapse and explosive burning. Such instabilities could enhance explosive yields by mixing hot ash with fuel, thereby accelerating nuclear burning, and affect the spectra of the supernova by dredging up heavy elements from greater depths in the star at early times. Our grid of models includes both blue supergiants and red supergiants over the range in progenitor mass expected for these events. We find that fluid instabilities driven by oxygen and helium burning ari...

  11. 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.

  12. A Search for Charged Massive Stable Particles at D0

    SciTech Connect (OSTI)

    Eads, Michael T

    2005-08-01T23:59:59.000Z

    A search for charged massive stable particles has been performed with the D0 detector at the Fermilab Tevatron. The signature is two particles reconstructed as muons, but with speed and invariant mass inconsistent with beam-produced muons. No excess of events is observed and limits are set on the production cross-section for pair-produced stable stau sleptons based on 390 pb{sup -1} of data. Limits vary from 0.06 pb to 0.62 pb, depending on the stau mass, and are the strictest Tevatron limits to date. Mass limits are also set for stable charginos. The limits are 140 GeV/c{sup 2} for a higgsino-like chargino and 174 GeV/c{sup 2} for a gaugino-like chargino. These are currently the best limits to date for stable charginos.

  13. Nanowire growth by an electron beam induced massive phase transformation

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

    Sood, Shantanu [State Univ., of New York, Stony Brook, NY (United States); Kisslinger, Kim [Brookhaven National Lab. (BNL), Upton, NY (United States); Gouma, Perena [State Univ., of New York, Stony Brook, NY (United States)

    2014-12-01T23:59:59.000Z

    Tungsten trioxide nanowires of a high aspect ratio have been synthesized in-situ in a TEM under an electron beam of current density 14A/cm² due to a massive polymorphic reaction. Sol-gel processed pseudocubic phase nanocrystals of tungsten trioxide were seen to rapidly transform to one dimensional monoclinic phase configurations, and this reaction was independent of the substrate on which the material was deposited. The mechanism of the self-catalyzed polymorphic transition and accompanying radical shape change is a typical characteristic of metastable to stable phase transformations in nanostructured polymorphic metal oxides. A heuristic model is used to confirm the metastable to stable growth mechanism. The findings are important to the control electron beam deposition of nanowires for functional applications starting from colloidal precursors.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Topologically Massive Spin-1 Particles and Spin-Dependent Potentials

    E-Print Network [OSTI]

    F. A. Gomes Ferreira; P. C. Malta; L. P. R. Ospedal; J. A. Helayël-Neto

    2015-04-27T23:59:59.000Z

    We investigate the role played by particular field representations of an intermediate massive spin-1 boson in the context of spin-dependent interparticle potentials between fermionic sources in the limit of low momentum transfer. The comparison between the well-known case of the Proca field and that of an exchanged spin-1 boson (with gauge-invariant mass) described by a 2-form potential mixed with a 4-vector gauge field is established in order to pursue an analysis of spin- as well as velocity-dependent profiles of the interparticle potentials. We discuss possible applications and derive an upper bound on the product of vector and pseudo-tensor coupling constants.

  20. Stochastic Acceleration in Relativistic Parallel Shocks

    E-Print Network [OSTI]

    Joni J. P. Virtanen; Rami Vainio

    2004-11-08T23:59:59.000Z

    (abridged) We present results of test-particle simulations on both the first and the second order Fermi acceleration at relativistic parallel shock waves. We consider two scenarios for particle injection: (i) particles injected at the shock front, then accelerated at the shock by the first order mechanism and subsequently by the stochastic process in the downstream region; and (ii) particles injected uniformly throughout the downstream region to the stochastic process. We show that regardless of the injection scenario, depending on the magnetic field strength, plasma composition, and the employed turbulence model, the stochastic mechanism can have considerable effects on the particle spectrum on temporal and spatial scales too short to be resolved in extragalactic jets. Stochastic acceleration is shown to be able to produce spectra that are significantly flatter than the limiting case of particle energy spectral index -1 of the first order mechanism. Our study also reveals a possibility of re-acceleration of the stochastically accelerated spectrum at the shock, as particles at high energies become more and more mobile as their mean free path increases with energy. Our findings suggest that the role of the second order mechanism in the turbulent downstream of a relativistic shock with respect to the first order mechanism at the shock front has been underestimated in the past, and that the second order mechanism may have significant effects on the form of the particle spectra and its evolution.

  1. 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.

  2. Parallel computation of Steiner Minimal Trees

    SciTech Connect (OSTI)

    Harris, F.C. Jr. [Univ. of Nevada, Reno, NV (United States)

    1995-12-01T23:59:59.000Z

    Given a set of N cities, construct a connected network which has minimum length. The problem is simple enough, but the catch is that you are allowed to add junctions in your network. Therefore the problem becomes how many extra junctions should be added, and where should they be placed so as to minimize the overall network length. This intriguing optimization problem is known as the Steiner Minimal Tree Problem (SMT), where the junctions that are added to the network are called Steiner Points. The focus of this paper is the parallel computation for the generation of what Pawel Winter termed T-list and its implementation. This generation of T-list is followed by the extraction of the proper answer. When Winter developed his algorithm, the time for extraction dominated the overall computation time. After Cockayne and Hewgill`s work, the time to generate T-list dominated the overall computation time. The ideas we present were implemented in a program called PARSTEINER94, and the results show that the time to generate T-list has now been cut by an order of magnitude. So now the extraction time once again dominates the overall computation time.

  3. 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)

  4. DIRECT DETECTION OF A FLARED DISK AROUND A YOUNG MASSIVE STAR HD200775 AND ITS 10 TO 1000 AU SCALE PROPERTIES

    SciTech Connect (OSTI)

    Okamoto, Yoshiko Kataza; Momose, M. [Institute of Astrophysics and Planetary Sciences, College of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512 (Japan); Kataza, Hirokazu [Department of Infrared Astrophysics, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Honda, M. [Department of Information Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293 (Japan); Fujiwara, H.; Sakon, I.; Onaka, T. [Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Ohashi, N. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China); Fujiyoshi, T. [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A'ohoku Place, Hilo, HI 96720 (United States); Sako, S.; Miyata, T. [Institute of Astronomy, School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Yamashita, T., E-mail: yokamoto@mx.ibaraki.ac.j [ELT Project, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2009-11-20T23:59:59.000Z

    We made mid-infrared (MIR) observations of the 10 M{sub sun} Herbig Be star HD200775 with the Cooled Mid-Infrared Camera and Spectrometer on the 8.2 m Subaru Telescope. We discovered diffuse emission of an elliptical shape extended in the north-south direction in an approx1000 AU radius around unresolved excess emission. The diffuse emission is perpendicular to the cavity wall formed by the past outflow activity and is parallel to the projected major axis of the central close binary orbit. The centers of the ellipse contours of the diffuse emission are shifted from the stellar position, and the amount of the shift increases as the contour brightness level decreases. The diffuse emission is well explained in all of geometry (the shape and the shift), size, and configuration by an inclined flared disk where only its surface emits the MIR photons. Our results give the first well-resolved infrared disk images around a massive star and strongly support that HD200775 is formed through the disk accretion. The disk survives the main accretion phase and shows a structure similar to that around lower mass stars with 'disk atmosphere'. At the same time, the disk also shows properties characteristic of massive stars such as photoevaporation traced by the 3.4 mm free-free emission and unusual silicate emission with a peak at 9.2 mum, which is shorter than that of many astronomical objects. It provides a good place to compare the disk properties between massive and lower mass stars.

  5. 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

  6. UCSB helps develop massive coastal radar network GARRY WORMSER, NEWS-PRESS CORRESPONDENT

    E-Print Network [OSTI]

    California at Santa Barbara, University of

    UCSB helps develop massive coastal radar network GARRY WORMSER, NEWS-PRESS CORRESPONDENT June 12, is experiencing a green resurgence in a massive mapping network of computerized systems that can save the lives., to Tijuana, Mexico. UCSB and other member institutions of the Southern California Coastal Ocean Observing

  7. 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.

  8. 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

  9. 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.

  10. An integrated approach to improving the parallel applications development process

    SciTech Connect (OSTI)

    Rasmussen, Craig E [Los Alamos National Laboratory; Watson, Gregory R [IBM; Tibbitts, Beth R [IBM

    2009-01-01T23:59:59.000Z

    The development of parallel applications is becoming increasingly important to a broad range of industries. Traditionally, parallel programming was a niche area that was primarily exploited by scientists trying to model extremely complicated physical phenomenon. It is becoming increasingly clear, however, that continued hardware performance improvements through clock scaling and feature-size reduction are simply not going to be achievable for much longer. The hardware vendor's approach to addressing this issue is to employ parallelism through multi-processor and multi-core technologies. While there is little doubt that this approach produces scaling improvements, there are still many significant hurdles to be overcome before parallelism can be employed as a general replacement to more traditional programming techniques. The Parallel Tools Platform (PTP) Project was created in 2005 in an attempt to provide developers with new tools aimed at addressing some of the parallel development issues. Since then, the introduction of a new generation of peta-scale and multi-core systems has highlighted the need for such a platform. In this paper, we describe some of the challenges facing parallel application developers, present the current state of PTP, and provide a simple case study that demonstrates how PTP can be used to locate a potential deadlock situation in an MPI code.

  11. Xyce Parallel Electronic Simulator : users' guide, version 4.1.

    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

    2009-02-01T23:59:59.000Z

    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.

  12. 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.

  13. 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.

  14. Wavelet analyses using parallel computing for plasma turbulence studies

    SciTech Connect (OSTI)

    Fujisawa, A.; Inagaki, S.; Matsuoka, K.; Itoh, S.-I. [Research Institute for Applied Mechanics and Itoh Research Center for Plasma Turbulence, Kyushu University, Kasuga-kouen, Kasuga 816-8580 (Japan); Shimizu, A.; Itoh, K. [National Institute for Fusion Science, Oroshi-cho, Toki-shi 509-52 (Japan); Nagashima, Y.; Yamada, T. [Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8561 (Japan)

    2010-10-15T23:59:59.000Z

    The wavelet analyses have been carried out, using a cluster of personal computer, on the signal of electric field fluctuations measured with heavy ion beam probes in the compact helical system stellarator. The results have revealed the intermittent characteristics of turbulence and of the nonlinear couplings between elemental waves of turbulence. The usage of parallel computing is found to successfully reduce the calculation time as inversely proportional to the CPU number used the cluster, which shows the nature of 'embarrassingly parallel computation'. The present example of the wavelet analyses clearly demonstrates the importance of the advanced analyzing methods and the parallel computation for the modern studies of plasma turbulence.

  15. Parallel Multiphysics Simulations of Charged Particles in Microfluidic Flows

    E-Print Network [OSTI]

    Bartuschat, Dominik

    2014-01-01T23:59:59.000Z

    The article describes parallel multiphysics simulations of charged particles in microfluidic flows with the waLBerla framework. To this end, three physical effects are coupled: rigid body dynamics, fluid flow modelled by a lattice Boltzmann algorithm, and electric potentials represented by a finite volume discretisation. For solving the finite volume discretisation for the electrostatic forces, a cell-centered multigrid algorithm is developed that conforms to the lattice Boltzmann meshes and the parallel communication structure of waLBerla. The new functionality is validated with suitable benchmark scenarios. Additionally, the parallel scaling and the numerical efficiency of the algorithms are analysed on an advanced supercomputer.

  16. 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.

  17. Parallel I/O Software Infrastructure for Large-Scale Systems

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

    Parallel IO Software Infrastructure for Large-Scale Systems Parallel IO Software Infrastructure for Large-Scale Systems | Tags: Math & Computer Science Choudhary.png An...

  18. 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

  19. 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.

  20. Design algorithms for parallel transmission in magnetic resonance imaging

    E-Print Network [OSTI]

    Setsompop, Kawin

    2008-01-01T23:59:59.000Z

    The focus of this dissertation is on the algorithm design, implementation, and validation of parallel transmission technology in Magnetic Resonance Imaging (MRI). Novel algorithms are proposed which yield excellent excitation ...

  1. 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...

  2. 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 ...

  3. Optimization Online - Parallel distributed-memory simplex for large ...

    E-Print Network [OSTI]

    Miles Lubin

    2012-04-17T23:59:59.000Z

    Apr 17, 2012 ... Parallel distributed-memory simplex for large-scale stochastic LP problems. Miles Lubin (mlubin ***at*** mcs.anl.gov) J. A. Julian Hall (j.a.j.hall ...

  4. Reducing Concurrency Bottlenecks in Parallel I/O Workloads

    SciTech Connect (OSTI)

    Manzanares, Adam C. [Los Alamos National Laboratory; Bent, John M. [Los Alamos National Laboratory; Wingate, Meghan [Los Alamos National Laboratory

    2011-01-01T23:59:59.000Z

    To enable high performance parallel checkpointing we introduced the Parallel Log Structured File System (PLFS). PLFS is middleware interposed on the file system stack to transform concurrent writing of one application file into many non-concurrently written component files. The promising effectiveness of PLFS makes it important to examine its performance for workloads other than checkpoint capture, notably the different ways that state snapshots may be later read, to make the case for using PLFS in the Exascale I/O stack. Reading a PLFS file involved reading each of its component files. In this paper we identify performance limitations on broader workloads in an early version of PLFS, specifically the need to build and distribute an index for the overall file, and the pressure on the underlying parallel file system's metadata server, and show how PLFS's decomposed components architecture can be exploited to alleviate bottlenecks in the underlying parallel file system.

  5. Evaluation of Parallel Decomposition Methods for Biomechanical Optimizations

    E-Print Network [OSTI]

    George, Alan D.

    that parallelizes the analysis function (i.e., a kinematic or dynamic simulation) called repeatedly by the optimizer , Jeffrey A. Reinbolt2,3 , Benjamin J. Fregly2,3 , and Alan D. George1 1 Department of Electrical & Computer

  6. A parallel fast multipole method for elliptic difference Sebastian Liska

    E-Print Network [OSTI]

    Colonius, Tim

    A parallel fast multipole method for elliptic difference equations Sebastian Liska , Tim Colonius Abstract A new fast multipole formulation for solving elliptic difference equations on unbounded domains multipole method. Unlike other fast multipole algorithms, our approach exploits the regularity

  7. 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...

  8. A hybrid parallel framework for computational solid mechanics

    E-Print Network [OSTI]

    Fidkowski, Piotr

    2011-01-01T23:59:59.000Z

    A novel, hybrid parallel C++ framework for computational solid mechanics is developed and presented. The modular and extensible design of this framework allows it to support a wide variety of numerical schemes including ...

  9. Parallel Stochastic Gradient Algorithms for Large-Scale Matrix ...

    E-Print Network [OSTI]

    2013-03-21T23:59:59.000Z

    parallel implementation that admits a speed-up nearly proportional to the ... On large-scale matrix completion tasks, Jellyfish is orders of magnitude more ...... get a consistent build of NNLS with mex optimizations at the time of this submission.

  10. 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 ...

  11. 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...

  12. 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 ...

  13. 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 ...

  14. 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...

  15. Implementation and testing of a parallel layer peeling algorithm

    E-Print Network [OSTI]

    Gandapur, Tasneem Kausar

    1996-01-01T23:59:59.000Z

    events into account. Two different implementations of the above mentioned serial algorithm viz., Layer Peeling and Characteristic Tracing have been previously described, and the characteristic tracing method has been implemented in parallel...

  16. Shot level parallelization of a seismic inversion code using PVM

    SciTech Connect (OSTI)

    Versteeg, R.J.; Gockenback, M.; Symes, W.W. [Rice Univ., Houston, TX (United States); Kern, M. [Inria, Le Chesnay (France)

    1994-12-31T23:59:59.000Z

    This paper presents experience with parallelization using PVM of DSO, a seismic inversion code developed in The Rice Inversion Project. It focuses on one aspect: trying to run efficiently on a cluster of 4 workstations. The authors use a coarse grain parallelism in which they dynamically distribute the shots over the available machines in the cluster. The modeling and migration of their code is parallelized very effectively by this strategy; they have reached a overall performance of 104 Mflops using a configuration of one manager with 3 workers, a speedup of 2.4 versus the serial version, which according to Amdahl`s law is optimal given the current design of their code. Further speedup is currently limited by the non parallelized part of their code optimization, linear algebra and i(o).

  17. 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 ...

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

    E-Print Network [OSTI]

    2014-07-10T23:59:59.000Z

    Jul 10, 2014 ... If G is a non trivial 2-connected series-parallel graph, an open nested ear decomposition ... no interior point of an ear Ei belongs to Ej for all j < i,.

  19. Provably good race detection that runs in parallel

    E-Print Network [OSTI]

    Fineman, Jeremy T

    2005-01-01T23:59:59.000Z

    A multithreaded parallel program that is intended to be deterministic may exhibit nondeterminism clue to bugs called determinacy races. A key capability of race detectors is to determine whether one thread executes logically ...

  20. Intelligent energy management agent for a parallel hybrid vehicle 

    E-Print Network [OSTI]

    Won, Jong-Seob

    2004-09-30T23:59:59.000Z

    This dissertation proposes an Intelligent Energy Management Agent (IEMA) for parallel hybrid vehicles. A key concept adopted in the development of an IEMA is based on the premise that driving environment would affect fuel ...