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  • 1
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    A method of smooth bivariate interpolation for data given on a generalized curvilinear grid (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: A method of locally bicubic interpolation is presented for data given at the nodes of a two-dimensional generalized curvilinear grid. The physical domain is transformed to a computational domain in which the grid is uniform and rectangular by a generalized curvilinear coordinate transformation. The metrics of the transformation are obtained by finite differences in the computational domain. Metric derivatives are determined by repeated application of the chain rule for partial differentiation. Given the metrics and the metric derivatives, the partial derivatives required to determine a locally bicubic interpolant can be estimated at each data point using finite differences in the computational domain. A bilinear transformation is used to analytically transform the individual quadrilateral cells in the physical domain into unit squares, thus allowing the use of simple formulas for bicubic interpolation.
    Keywords: STATISTICS AND PROBABILITY
    Type: SIAM Journal on Scientific and Statistical Computing (ISSN 0196-5204); 13; 3; p. 687-693.
    Format: text
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  • 2
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    Multiprocessing on supercomputers for computational aerodynamics (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Little use is made of multiple processors available on current supercomputers (computers with a theoretical peak performance capability equal to 100 MFLOPS or more) to improve turnaround time in computational aerodynamics. The productivity of a computer user is directly related to this turnaround time. In a time-sharing environment, such improvement in this speed is achieved when multiple processors are used efficiently to execute an algorithm. The concept of multiple instructions and multiple data (MIMD) is applied through multitasking via a strategy that requires relatively minor modifications to an existing code for a single processor. This approach maps the available memory to multiple processors, exploiting the C-Fortran-Unix interface. The existing code is mapped without the need for developing a new algorithm. The procedure for building a code utilizing this approach is automated with the Unix stream editor.
    Keywords: COMPUTER SYSTEMS
    Type: International Journal of Supercomputer Applications (ISSN 0890-2720); 5; 46-72
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  • 3
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    The NAS Parallel Benchmarks 2.1 Results (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: We present performance results for version 2.1 of the NAS Parallel Benchmarks (NPB) on the following architectures: IBM SP2/66 MHz; SGI Power Challenge Array/90 MHz; Cray Research T3D; and Intel Paragon. The NAS Parallel Benchmarks are a widely-recognized suite of benchmarks originally designed to compare the performance of highly parallel computers with that of traditional supercomputers.
    Keywords: Computer Systems
    Type: NASA-TM-112038 , NAS 1.15:112038 , NAS-96-010
    Format: application/pdf
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  • 4
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    Pulsed plane wave analytic solutions for generic shapes and the validation of Maxwell's equations solvers (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Generic shapes are subjected to pulsed plane waves of arbitrary shape. The resulting scattered electromagnetic fields are determined analytically. These fields are then computed efficiently at field locations for which numerically determined EM fields are required. Of particular interest are the pulsed waveform shapes typically utilized by radar systems. The results can be used to validate the accuracy of finite difference time domain Maxwell's equations solvers. A two-dimensional solver which is second- and fourth-order accurate in space and fourth-order accurate in time is examined. Dielectric media properties are modeled by a ramping technique which simplifies the associated gridding of body shapes. The attributes of the ramping technique are evaluated by comparison with the analytic solutions.
    Keywords: PHYSICS (GENERAL)
    Type: AIAA PAPER 92-0016
    Format: text
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  • 5
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    Multi-processing on supercomputers for computational aerodynamics (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The MIMD concept is applied, through multitasking, with relatively minor modifications to an existing code for a single processor. This approach maps the available memory to multiple processors, exploiting the C-FORTRAN-Unix interface. An existing single processor algorithm is mapped without the need for developing a new algorithm. The procedure of designing a code utilizing this approach is automated with the Unix stream editor. A Multiple Processor Multiple Grid (MPMG) code is developed as a demonstration of this approach. This code solves the three-dimensional, Reynolds-averaged, thin-layer and slender-layer Navier-Stokes equations with an implicit, approximately factored and diagonalized method. This solver is applied to a generic, oblique-wing aircraft problem on a four-processor computer using one process for data management and nonparallel computations and three processes for pseudotime advance on three different grid systems.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: AIAA PAPER 90-0337
    Format: text
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  • 6
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    A direct procedure for interpolation on a structured curvilinear two-dimensional grid (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A direct procedure is presented for locally bicubic interpolation on a structured, curvilinear, two-dimensional grid. The physical (Cartesian) space is transformed to a computational space in which the grid is uniform and rectangular by a generalized curvilinear coordinate transformation. Required partial derivative information is obtained by finite differences in the computational space. The partial derivatives in physical space are determined by repeated application of the chain rule for partial differentiation. A bilinear transformation is used to analytically transform the individual quadrilateral cells in physical space into unit squares. The interpolation is performed within each unit square using a piecewise bicubic spline.
    Keywords: NUMERICAL ANALYSIS
    Type: NASA-TM-102213 , A-89210 , NAS 1.15:102213
    Format: application/pdf
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  • 7
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    Communication Improvement for the LU NAS Parallel Benchmark: A Model for Efficient Parallel Relaxation Schemes (1997)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: The first release of the MPI version of the LU NAS Parallel Benchmark (NPB2.0) performed poorly compared to its companion NPB2.0 codes. The later LU release (NPB2.1 & 2.2) runs up to two and a half times faster, thanks to a revised point access scheme and related communications scheme. The new scheme sends substantially fewer messages. is cache "friendly", and has a better load balance. We detail the, observations and modifications that resulted in this efficiency improvement, and show that the poor behavior of the original code resulted from deriving a message passing scheme from an algorithm originally devised for a vector architecture.
    Keywords: Computer Systems
    Type: NAS-97-032
    Format: text
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  • 8
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    New NAS Parallel Benchmarks Results (1997)
    In:  Other Sources
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    Publication Date: 2019-07-18
    Description: NPB2 (NAS (NASA Advanced Supercomputing) Parallel Benchmarks 2) is an implementation, based on Fortran and the MPI (message passing interface) message passing standard, of the original NAS Parallel Benchmark specifications. NPB2 programs are run with little or no tuning, in contrast to NPB vendor implementations, which are highly optimized for specific architectures. NPB2 results complement, rather than replace, NPB results. Because they have not been optimized by vendors, NPB2 implementations approximate the performance a typical user can expect for a portable parallel program on distributed memory parallel computers. Together these results provide an insightful comparison of the real-world performance of high-performance computers. New NPB2 features: New implementation (CG), new workstation class problem sizes, new serial sample versions, more performance statistics.
    Keywords: Computer Systems
    Type: SuperComputing ''97 Meeting; Nov 15, 1997 - Nov 21, 1997; San Jose, CA; United States
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  • 9
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    ScyFlow: An Environment for the Visual Specification and Execution of Scientific Workflows (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: With the advent of grid technologies, scientists and engineers are building more and more complex applications to utilize distributed grid resources. The core grid services provide a path for accessing and utilizing these resources in a secure and seamless fashion. However what the scientists need is an environment that will allow them to specify their application runs at a high organizational level, and then support efficient execution across any given set or sets of resources. We have been designing and implementing ScyFlow, a dual-interface architecture (both GUT and APT) that addresses this problem. The scientist/user specifies the application tasks along with the necessary control and data flow, and monitors and manages the execution of the resulting workflow across the distributed resources. In this paper, we utilize two scenarios to provide the details of the two modules of the project, the visual editor and the runtime workflow engine.
    Keywords: Computer Programming and Software
    Type: GGF #10 Workflo Workshop; Mar 09, 2004 - Mar 13, 2004; Berlin; Germany
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  • 10
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    Software for Managing Parametric Studies (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: The Information Power Grid Virtual Laboratory (ILab) is a Practical Extraction and Reporting Language (PERL) graphical-user-interface computer program that generates shell scripts to facilitate parametric studies performed on the Grid. (The Grid denotes a worldwide network of supercomputers used for scientific and engineering computations involving data sets too large to fit on desktop computers.) Heretofore, parametric studies on the Grid have been impeded by the need to create control language scripts and edit input data files painstaking tasks that are necessary for managing multiple jobs on multiple computers. ILab reflects an object-oriented approach to automation of these tasks: All data and operations are organized into packages in order to accelerate development and debugging. A container or document object in ILab, called an experiment, contains all the information (data and file paths) necessary to define a complex series of repeated, sequenced, and/or branching processes. For convenience and to enable reuse, this object is serialized to and from disk storage. At run time, the current ILab experiment is used to generate required input files and shell scripts, create directories, copy data files, and then both initiate and monitor the execution of all computational processes.
    Keywords: Man/System Technology and Life Support
    Type: ARC-14649-1 , NASA Tech Briefs, September 2003; 13
    Format: application/pdf
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