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  • 1
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    The Efficiency and the Scalability of an Explicit Operator on an IBM POWER4 System (2002)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: We present an evaluation of the efficiency and the scalability of an explicit CFD operator on an IBM POWER4 system. The POWER4 architecture exhibits a common trend in HPC architectures: boosting CPU processing power by increasing the number of functional units, while hiding the latency of memory access by increasing the depth of the memory hierarchy. The overall machine performance depends on the ability of the caches-buses-fabric-memory to feed the functional units with the data to be processed. In this study we evaluate the efficiency and scalability of one explicit CFD operator on an IBM POWER4. This operator performs computations at the points of a Cartesian grid and involves a few dozen floating point numbers and on the order of 100 floating point operations per grid point. The computations in all grid points are independent. Specifically, we estimate the efficiency of the RHS operator (SP of NPB) on a single processor as the observed/peak performance ratio. Then we estimate the scalability of the operator on a single chip (2 CPUs), a single MCM (8 CPUs), 16 CPUs, and the whole machine (32 CPUs). Then we perform the same measurements for a chache-optimized version of the RHS operator. For our measurements we use the HPM (Hardware Performance Monitor) counters available on the POWER4. These counters allow us to analyze the obtained performance results.
    Keywords: Computer Operations and Hardware
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  • 2
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    Systematic Underutilization of Glutamine In Thermophile Proteins (2002)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: Rapid racemization above 100 C of L-amino acids to Domino acids, as well as deamidation, is probably a hazard for high temperature life. For example, the half-life of some asparaginyl peptides can be as short as 10 minutes at 100 C. High temperature organisms could protect themselves by reducing usage of amino acids that are easily racemized/deamidazed, by having a rapid rate of protein turnover which requires energy, or by adapting special cis-peptide conformations. We have searched eight completely sequenced thermophile genomes, and compare them to mesophile genomes, in order to identify underutilized amino acids. To our surprise, asparagine, the most unstable amino acid to deamidation, is used at about the same level in thermophile proteins in comparison to mesophiles whereas it is the second most unstable amino acid, glutamine, that is underutilized in all of eight thermophile species. Glutamines are present at 2% level in a typical thermophile protein, instead of 4% in mesophile. We argue that it is easier to protect asparagines from deamidation by cis-peptide conformations. We discuss statistical as well as structural evidence in support of our conclusions.
    Keywords: Inorganic, Organic and Physical Chemistry
    Type: Genome Informatics; Sep 04, 2002 - Sep 08, 2002; Cambridge; United Kingdom
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  • 3
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    Simulation of Ultra-Small Electronic Devices: The Classical-Quantum Transition Region (1997)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: Concern is increasing about how quantum effects will impact electronic device operation as down-scaling continues along the SIA Roadmap through 2010. This document describes part of a new semiconductor device modeling (SDM) program at NAS to investigate these concerns by utilizing advanced NAS and third-party numerical computation software to rapidly implement and investigate electronic device models including quantum effects. This SDM project will investigate quantum effects in devices in the classical-quantum transition region, especially sub-0.1 mm MOSFETs. Specific tasks planned for this project include the use of quantum corrections to the classical drift-diffusion and hydrodynamic models of electron transport, arid the use of nominally quantum models including significant scattering.
    Keywords: Electronics and Electrical Engineering
    Type: NAS-97-028
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  • 4
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    Are Fibre Channel SANs a Commodity? (2000)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: The goal of this work is to evaluate the feasibility of putting together a Fibre Channel Storage Area Network with heterogeneous hardware running both open-source and commercial operating systems. Adherence to the Fibre Channel Specification is supposed to guarantee interoperability in such an environment. We also want to evaluate how difficult it might be to put together a SAN using open-source components. While all the commercial vendors provide Fibre Channel support, this comes at a cost, e.g., not only O/S and drivers, but usually an expensive support contract. The open-source model could lower the cost of building and maintaining a SAN. Of course, for this to be the case, the open-source platforms would have to provide the functionality to construct a SAN. We are assembling a Fibre Channel SAN from heterogeneous hardware (i386, alpha, sparc) running *BSD, Linux, Tru64, NT and Solaris operating systems. We are running several tests to investigate the level of Fibre Channel support provided by each OS. Our current testbed is specified in the table below. Currently, it only contains open-source platforms. We plan to add a PC running OpenBSD, as well as the following commercial systems: Sun Ultra 1/Solaris, DEC AlphaServer 4000/Tru64 Unix, Pentium Pro PC/Windows NT.
    Keywords: Computer Operations and Hardware
    Type: USENIX Annual Technical Meeting; Jun 01, 2001; Boston, MA; United States
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  • 5
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    Performance and Scalability of the NAS Parallel Benchmarks in Java (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Several features make Java an attractive choice for scientific applications. In order to gauge the applicability of Java to Computational Fluid Dynamics (CFD), we have implemented the NAS (NASA Advanced Supercomputing) Parallel Benchmarks in Java. The performance and scalability of the benchmarks point out the areas where improvement in Java compiler technology and in Java thread implementation would position Java closer to Fortran in the competition for scientific applications.
    Keywords: Computer Programming and Software
    Type: IPDPS 2003: 17th annual International Parallel and Distributed Processing Symposium; Apr 22, 2003 - Apr 26, 2003; Nice; France|International Workshop on Java for Parallel and Distributed Programming; Apr 22, 2003 - Apr 26, 2003; Nice; France
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  • 6
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    Nanotechnology Based Materials and Devices for Health Care (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This viewgraph presentation provides information on trends in NASA nanotechnology research and development, and future biotechnological applications for that nanotechnology. The presentation covers nanoelectronics, nanosensors, and nanomaterials, biomimetics, devices and materials for health care, carbon nanotubes, biosensors for astrobiology, solid-state nanopores for DNA sequencing, and protein nanotubes.
    Keywords: Solid-State Physics
    Type: SASTRA International Conference; Jan 11, 2003 - Jan 12, 2003; Thanjavur; India
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  • 7
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    Computational Nanotechnology of Nanotubes, Composites, and Electronics (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This viewgraph presentation addresses carbon nanotubes, their mechanical and thermal properties, and their structure, as well as possible miniature devices which may be assembled in the future from carbon nanotubes.
    Keywords: Solid-State Physics
    Type: US National Congress of Applied Mechanics (USNCAM); Jun 24, 2002 - Jun 27, 2002; Blacksburg, VA; United States|World Congress on Computational Mechanics (WCCM); Jul 07, 2002 - Jul 12, 2002; Vienna; Austria|International Conference on Computational Engineering and Sciences (ICES); Jul 31, 2002 - Aug 02, 2002; Reno, NV; United States
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  • 8
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    Navigation in Grid Space with the NAS Grid Benchmarks (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: We present a navigational tool for computational grids. The navigational process is based on measuring the grid characteristics with the NAS Grid Benchmarks (NGB) and using the measurements to assign tasks of a grid application to the grid machines. The tool allows the user to explore the grid space and to navigate the execution at a grid application to minimize its turnaround time. We introduce the notion of gridscape as a user view of the grid and show how it can be me assured by NGB, Then we demonstrate how the gridscape can be used with two different schedulers to navigate a grid application through a rudimentary grid.
    Keywords: Computer Systems
    Type: HPDC-11; Jul 24, 2002 - Jul 26, 2002; Edinburgh; United Kingdom
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  • 9
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    High-Order Central WENO Schemes for 1D Hamilton-Jacobi Equations (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: In this paper we derive fully-discrete Central WENO (CWENO) schemes for approximating solutions of one dimensional Hamilton-Jacobi (HJ) equations, which combine our previous works. We introduce third and fifth-order accurate schemes, which are the first central schemes for the HJ equations of order higher than two. The core ingredient is the derivation of our schemes is a high-order CWENO reconstructions in space.
    Keywords: Theoretical Mathematics
    Type: ENUmath 2001; Jan 01, 2001; Unknown
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  • 10
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    Diode-Laser Pumped Far-Infrared Local Oscillator Based on Semiconductor Quantum Wells (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The contents include: 1) Tetrahertz Field: A Technology Gap; 2) Existing THZ Sources and Shortcomings; 3) Applications of A THZ Laser; 4) Previous Optical Pumped LW Generations; 5) Optically Pumped Sb based Intersubband Generation Whys; 6) InGaAs/InP/AlAsSb QWs; 7) Raman Enhanced Optical Gain; 8) Pump Intensity Dependence of THZ Gain; 9) Pump-Probe Interaction Induced Raman Shift; 10) THZ Laser Gain in InGaAs/InP/AlAsSb QWs; 11) Diode-Laser Pumped Difference Frequency Generation (InGaAs/InP/AlAsSb QWs); 12) 6.1 Angstrom Semiconductor Quantum Wells; 13) InAs/GaSb/AlSb Nanostructures; 14) InAs/AlSb Double QWs: DFG Scheme; 15) Sb-Based Triple QWs: Laser Scheme; and 16) Exciton State Pumped THZ Generation. This paper is presented in viewgraph form.
    Keywords: Instrumentation and Photography
    Type: FIR-IR, Sub-MM and MM Detector Technology Workshop; Apr 01, 2002 - Apr 03, 2002; Monterey, CA; United States
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