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Single Processor (single + processor)

Distribution by Scientific Domains

Engineering	83%

Selected Abstracts

Micro-mechanical simulation of geotechnical problems using massively parallel computers

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 14 2003
David W. Washington
Abstract This paper demonstrates that the architecture of a massively parallel computer can be adapted for micro-mechanical simulations of a Geotechnical problem. The Discrete Element Method was used on a massively parallel supercomputer to simulate Geotechnical boundary value problems. For the demonstration, a triaxial test was simulated using an algorithm titled ,TRUBAL for Parallel Machines (TPM)' based on the discrete element method (DEM). In this trial demonstration, the inherent parallelism within DEM algorithm is shown. Then a comparison is made between the parallel algorithm (TPM) and the serial algorithm (TRUBAL) to show the benefits of this research. TPM showed substantial improvement in performance with increasing number of processors when compared with TRUBAL using single processor. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Evaluating recursive filters on distributed memory parallel computers

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 11 2006
Przemys, aw Stpiczy, skiArticle first published online: 6 APR 200
Abstract The aim of this paper is to show that the recently developed high performance divide and conquer algorithm for solving linear recurrence systems with constant coefficients together with the new BLAS-based algorithm for narrow-banded triangular Toeplitz matrix,vector multiplication, allow to evaluate linear recursive filters efficiently on distributed memory parallel computers. We apply the BSP model of parallel computing to predict the behaviour of the algorithm and to find the optimal values of the method's parameters. The results of experiments performed on a cluster of twelve dual-processor Itanium 2 computers and Cray X1 are also presented and discussed. The algorithm allows to utilize up to 30% of the peak performance of 24 Itanium processors, while a simple scalar algorithm can only utilize about 4% of the peak performance of a single processor. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Parallel eigenanalysis of multiaquifer systems

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 15 2005
L. Bergamaschi
Abstract Finite element discretizations of flow problems involving multiaquifer systems deliver large, sparse, unstructured matrices, whose partial eigenanalysis is important for both solving the flow problem and analysing its main characteristics. We studied and implemented an effective preconditioning of the Jacobi,Davidson algorithm by FSAI-type preconditioners. We developed efficient parallelization strategies in order to solve very large problems, which could not fit into the storage available to a single processor. We report our results about the solution of multiaquifer flow problems on an SP4 machine and a Linux Cluster. We analyse the sequential and parallel efficiency of our algorithm, also compared with standard packages. Questions regarding the parallel solution of finite element eigenproblems are addressed and discussed. Copyright © 2005 John Wiley & Sons, Ltd. [source]

A class of parallel multiple-front algorithms on subdomains

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 11 2003
A. Bose
Abstract A class of parallel multiple-front solution algorithms is developed for solving linear systems arising from discretization of boundary value problems and evolution problems. The basic substructuring approach and frontal algorithm on each subdomain are first modified to ensure stable factorization in situations where ill-conditioning may occur due to differing material properties or the use of high degree finite elements (p methods). Next, the method is implemented on distributed-memory multiprocessor systems with the final reduced (small) Schur complement problem solved on a single processor. A novel algorithm that implements a recursive partitioning approach on the subdomain interfaces is then developed. Both algorithms are implemented and compared in a least-squares finite-element scheme for viscous incompressible flow computation using h - and p -finite element schemes. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Coupled solution of the species conservation equations using unstructured finite-volume method

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 4 2010
Ankan Kumar
Abstract A coupled solver was developed to solve the species conservation equations on an unstructured mesh with implicit spatial as well as species-to-species coupling. First, the computational domain was decomposed into sub-domains comprised of geometrically contiguous cells,a process similar to additive Schwarz decomposition. This was done using the binary spatial partitioning algorithm. Following this step, for each sub-domain, the discretized equations were developed using the finite-volume method, and solved using an iterative solver based on Krylov sub-space iterations, that is, the pre-conditioned generalized minimum residual solver. Overall (outer) iterations were then performed to treat explicitness at sub-domain interfaces and nonlinearities in the governing equations. The solver is demonstrated for both two-dimensional and three-dimensional geometries for laminar methane,air flame calculations with 6 species and 2 reaction steps, and for catalytic methane,air combustion with 19 species and 24 reaction steps. It was found that the best performance is manifested for sub-domain size of 2000 cells or more, the exact number depending on the problem at hand. The overall gain in computational efficiency was found to be a factor of 2,5 over the block (coupled) Gauss,Seidel procedure. All calculations were performed on a single processor machine. The largest calculations were performed for about 355 000 cells (4.6 million unknowns) and required 900,MB of peak runtime memory and 19,h of CPU on a single processor. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Toward responsive visualization services for scatter/gather browsing

PROCEEDINGS OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE & TECHNOLOGY (ELECTRONIC), Issue 1 2008
Weimao Ke
As a type of relevance feedback, Scatter/Gather demonstrates an interactive approach to relevance mapping and reinforcement. The Scatter/Gather model, proposed by Cutting, Karger, Pedersen, and Tukey (1992), is well known for its effectiveness in situations where it is difficult to precisely specify a query. However, online clustering on a large data corpus is computationally complex and extremely time consuming. This has prohibited the method's real world application for responsive services. In this paper, we proposed and evaluated a new clustering algorithm called LAIR2, which has linear worst-case time complexity and constant running time average for Scatter/Gather browsing. Our experiment showed when running on a single processor, the LAIR2 online clustering algorithm is several hundred times faster than a classic parallel algorithm running on multiple processors. The efficiency of the LAIR2 algorithm promises real-time Scatter/Gather browsing services. We have implemented an online visualization prototype, namely, LAIR2 Scatter/Gather browser, to demonstrate its utility and usability. [source]