HPCCP/CAS Workshop Proceedings 1998

This publication is a collection of extended abstracts of presentations given at the HPCCP/CAS (High Performance Computing and Communications Program/Computational Aerosciences Project) Workshop held on August 24-26, 1998, at NASA Ames Research Center, Moffett Field, California. The objective of the Workshop was to bring together the aerospace high performance computing community, consisting of airframe and propulsion companies, independent software vendors, university researchers, and government scientists and engineers. The Workshop was sponsored by the HPCCP Office at NASA Ames Research Center. The Workshop consisted of over 40 presentations, including an overview of NASA's High Performance Computing and Communications Program and the Computational Aerosciences Project; ten sessions of papers representative of the high performance computing research conducted within the Program by the aerospace industry, academia, NASA, and other government laboratories; two panel sessions; and a special presentation by Mr. James Bailey

A review of literature on parallel constraint solving

As multicore computing is now standard, it seems irresponsible for constraints researchers to ignore the implications of it. Researchers need to address a number of issues to exploit parallelism, such as: investigating which constraint algorithms are amenable to parallelisation; whether to use shared memory or distributed computation; whether to use static or dynamic decomposition; and how to best exploit portfolios and cooperating search. We review the literature, and see that we can sometimes do quite well, some of the time, on some instances, but we are far from a general solution. Yet there seems to be little overall guidance that can be given on how best to exploit multicore computers to speed up constraint solving. We hope at least that this survey will provide useful pointers to future researchers wishing to correct this situation

Semiannual report, 1 October 1990 - 31 March 1991

Research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, numerical analysis, and computer science is summarized

An Adaptive Finite Element Methodology for the High-Performance Computer Simulation of Multiphase Flow Processes.

A methodology has been developed for the computer simulation of multiphase flow processes in porous media. The solutions to the nonlinear equations describing these processes are approximated by Galerkin\u27s method on the spatial dimensions and the finite difference method on the temporal dimension. Due to the transient nature of discontinuities in the spatial domain, dynamic mesh refinement (and unrefinement) techniques, based on the maintenance of a 1-irregular mesh, are employed on a two dimensional mesh to produce fine resolution in regions of activity and coarse resolution elsewhere. Our unique approach is tested by comparing computed results with data from laboratory experiments. The groundwork for extending this approach to three dimensional problems is laid in the development of a new finite element for use in 1-irregular adaptive schemes. We describe the development of this element, prove its correctness, and demonstrate its utility in a test problem. Finally, a three dimensional static-mesh version of the approach is distributed over a cluster of workstations, utilizing PVM for message passing. The repeated solution of large systems of equations dominates the computations, and is the focus of the effort in parallelization. Substructuring techniques are employed, allowing for efficient coarse-grained computations due to the distribution of expensive matrix operations over multiprocessors. An analysis of the performance characteristics of this approach is given, followed by a description of tests on a real-world problem

Parallel finite element modeling of the hydrodynamics in agitated tanks

Mixing in the transition flow regime -- Technology to mix in transition flow regime -- Methods to characterize mixing hydrodynamics -- Challenges to numerically model transition flow regime in agited tanks -- Transition flow regime in agitated tanks -- Parallel computing -- Numerical modeling of the agitators motion -- Overall methodological approach -- Computational resources -- Program development strategy -- Parallel finite element simulations of incompressible viscous fluid flow by domain decomposition with Lagrange multipliers -- Parallel numerical model -- Parallel implementation -- Three-dimensional benchmark cases -- A parallel finite element sliding mesh technique for the Navier-Stokes equation -- Numerical method -- Parallel implementation -- Numerical examples -- Parallel performance -- Finite element modeling of the laminar and transition flow of the Superblend dual shaft coaxial mixer on parallel computers -- Superblend coaxial mixer configuration -- Numerical model -- Hydrodynamics in Superblend coaxial mixer -- Mixing -- Mixing efficiency -- Parallel finite element solver -- Parallel sliding mesh technique -- Simulation of the hydrodynamics of a stirred tank in the transition regime -- Recommendations for future research -- Parallel algorithms -- Simulation of agited and the transition flow regime

Working Notes from the 1992 AAAI Workshop on Automating Software Design. Theme: Domain Specific Software Design

The goal of this workshop is to identify different architectural approaches to building domain-specific software design systems and to explore issues unique to domain-specific (vs. general-purpose) software design. Some general issues that cut across the particular software design domain include: (1) knowledge representation, acquisition, and maintenance; (2) specialized software design techniques; and (3) user interaction and user interface

Research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, numerical analysis, and computer science

Research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, numerical analysis, and computer science is summarized