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Journal of Zhejiang University-science C(computers and Electronics) 2012年第8期13卷 559-564页

作者： Young Joon AHN Christoph M. HOFFMANN Paul ROSEN Department of Mathematics Education Chosun University Gwangju 501-759 Korea Department of Computer Science Purdue University West Lafayette IN 47907 USA Scientific Computing and Imaging Institute University of Utah Salt Lake City UT 84112 USA

The problem of packing circles into a domain of prescribed topology is considered. The circles need not have equal radii. The Collins-Stephenson algorithm computes such a circle packing. This algorithm is parMlelized in two different ways and its performance is reported for a triangular, planar domain test case. The implementation uses the highly parallel graphics processing unit （GPU） on commodity hardware. The speedups so achieved are discussed based on a number of experiments.

关键词： Circle packing Algorithm performance Parallel computation Graphics processing unit （GPU）

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A parallel cellular genetic algorithm used in finite element simulation 4th

A parallel cellular genetic algorithm used in finite element...

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International Conference on Evolutionary Computation - 4th International Conference on Parallel Problem Solving from Nature, PPSN 1996

作者： Schoneveld, A. De Ronde, J.F. Sloot, P. Kaandorp, J.A. Parallel Scientific Computing and Simulation Group Computer Science Physics and Astronomy University of Amsterdam Kruislaan 403 Amsterdam1098 SJ Netherlands

ISBN: (纸本)354061723X

In this paper we will formulate a framework for a parallel population based search process: an Abstract Cellular Genetic Algorithm (ACGA). Using the ACGA as a template, various parallel search algorithms can be formulated, e.g. parallel Genetic Algorithms and parallel Simulated Annealing. As a case study we will investigate the influence of locality on the behaviour of a Cellular Genetic Algorithm (CGA), that is constructed according to this framework. A neighbourhood structure is imposed upon the population, which results in overlapping local cell-populations. Using varying neighbourhood sizes, we will discuss experiments with CGAs ranging from maximally local to effectively global. The CGA has been applied to a load balancing problem: the NP-hard problem of mapping a process graph onto a processor topology in parallel finite element simulations. © 1996, Springer-Verlag. All rights reserved.

关键词： Topology

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A language-independent api for unstructured mesh access and manipulation

A language-independent api for unstructured mesh access and ...

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21st International Symposium on High Performance computing Systems and Applications, HPCS 2007

作者： Ollivier-Gooch, Carl Diachin, Lori Freitag Shephard, Mark S. Tautges, Timothy Advanced Numerical Simulation Laboratory University of British Columbia Center for Applied Scientific Computing Lawrence Livermore National Laboratory Scientific Computing Research Center Rensselaer Polytechnic Institute Mathematics and Computer Science Division Argonne National Laboratory

ISBN: (纸本)0769528139

Software for numerical solution of partial differential equations requires accessing, manipulating, and often modifying information about the geometry of the computational domain, the mesh used for the simulation, and discrete data stored on that mesh. Typically, applications programmers would prefer to avoid the difficulty and complexity of creating their own modules for tasks like interacting with multiple geometric modelers, mesh adaptation, and optimization algorithms, rightly preferring instead to focus on the problem physics and on studying the physical results that the codeproduces. Ideally, these modules would be provided by experts in CAD modeling, meshing, and optimization, and written so that they can use the application's data regardless of the data structures used by the application. This paper describes a language- and data-structure-independent interface supporting query and modification of mesh data conforming to a general abstract data model. © 2007 IEEE.

关键词： Application programming interfaces (API)

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Experimental evaluation of BSP programming libraries

Experimental evaluation of BSP programming libraries

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作者： Krusche, Peter Loulergue, F. Tiskin, A. Department of Computer Science Centre for Scientific Computing University of Warwick Coventry CV4 7AL United Kingdom

The model of bulk-synchronous parallel computation (BSP) helps to implement portable general purpose algorithms while maintaining predictable performance on different parallel computers. Nevertheless, when programming in 'BSP style', the running time of the implementation of an algorithm can be very dependent on the underlying communication library. In this study, an overview of existing approaches to practical BSP programming in C/C or Fortran is given and benchmarks were run for the two main BSP-like communication libraries, the Oxford BSP Toolset and PUB. Furthermore, a memory efficient matrix multiplication algorithm was implemented and used to compare their performance on different parallel computers and to evaluate the compliance with predictions by theoretical results. © 2008 World scientific Publishing Company.

关键词： Parallel processing systems

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Minimum Height Drawings of Ordered Trees in Polynomial Time: Homotopy Height of Tree Duals 38

Minimum Height Drawings of Ordered Trees in Polynomial Time:...

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38th International Symposium on Computational Geometry, SoCG 2022

作者： Ophelders, Tim Parsa, Salman Department of Information and Computing Science Utrecht University Netherlands Department of Mathematics and Computer Science TU Eindhoven Netherlands Scientific Computing and Imaging Institute University of Utah Salt Lake CityUT United States

ISBN: (纸本)9783959772273

We consider drawings of graphs in the plane in which vertices are assigned distinct points in the plane and edges are drawn as simple curves connecting the vertices and such that the edges intersect only at their common endpoints. There is an intuitive quality measure for drawings of a graph that measures the height of a drawing ?: G,? R2 as follows. For a vertical line l in R2, let the height of l be the cardinality of the set l n ?(G). The height of a drawing of G is the maximum height over all vertical lines. In this paper, instead of abstract graphs, we fix a drawing and consider plane graphs. In other words, we are looking for a homeomorphism of the plane that minimizes the height of the resulting drawing. This problem is equivalent to the homotopy height problem in the plane, and the homotopic Fréchet distance problem. These problems were recently shown to lie in NP, but no polynomial-time algorithm or NP-hardness proof has been found since their formulation in 2009. We present the first polynomial-time algorithm for drawing trees with optimal height. This corresponds to a polynomial-time algorithm for the homotopy height where the triangulation has only one vertex (that is, a set of loops incident to a single vertex), so that its dual is a tree. © Tim Ophelders and Salman Parsa;licensed under Creative Commons License CC-BY 4.0

关键词： Trees (mathematics)

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Parallel multilevel block ILU preconditioning techniques for large sparse linear systems

Parallel multilevel block ILU preconditioning techniques for...

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International Parallel and Distributed Processing Symposium, IPDPS 2003

作者： Shen, Chi Zhang, Jun Wang, Kai Laboratory for High Performance Scientific Computing and Computer Simulation Department of Computer Science University of Kentucky 773 Anderson Hall LexingtonKY40506-0046 United States

ISBN: (纸本)0769519261

We present a class of parallel preconditioning strategies built on a multilevel block incomplete LU (ILU)factorization technique to solve large sparse linear systems on distributed memory parallel computers. The preconditioners are constructed by using the concept of block independent sets. Two algorithms for constructing block independent sets of a distributed sparse matrix are proposed. We compare a few implementations of the parallel multilevel ILU preconditioners with different block independent set algorithms and different coarse level solution strategies. We also use some diagonal thresholding and perturbation strategies to enhance factorization stability. Numerical experiments indicate that our parallel multilevel block ILU preconditioners are robust and efficient. © 2003 IEEE.

关键词： Factorization

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Electronic structure calculations for muon spectroscopy

Electronic Structure

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Electronic Structure 2025年第2期7卷

作者： Blundell, Stephen J. Bonacci, Miki Bonfà, Pietro De Renzi, Roberto Huddart, Benjamin M. Lancaster, Tom Liborio, Leandro M Onuorah, Ifeanyi J. Pizzi, Giovanni Pratt, Francis L. Wilkinson, John M Department of Physics University of Oxford Parks Road OxfordOX1 3PU United Kingdom Villigen PSICH-5232 Switzerland Department of Mathematical Physical and Computer Sciences University of Parma Parco Area delle Scienze 7/A Parma43124 Italy Department of Physics Durham University South Road DurhamDH1 3LE United Kingdom Scientific Computing Department Science and Technology Facilities Council Rutherford Appleton Laboratory Harwell Campus DidcotOX11 0QX United Kingdom ISIS Neutron and Muon Source STFC Rutherford Appleton Laboratory Chilton DidcotOX11 0QX United Kingdom

Muon spectroscopy has become a leading tool for the investigation of local magnetic fields in condensed matter physics, finding applications in the study of superconductivity, magnetism, ionic diffusion in battery materials, and numerous other fields. Though the muon yields quantitative information about the material, this can only be fully interpreted if the nature of the muon site and its stability is fully understood. Electronic structure calculations are of paramount importance for providing this understanding, particularly through a group of techniques that has become known as DFT + μ , density functional theory including the presence of the implanted muon. We describe how these electronic structure calculations can be used to underpin muon spectroscopy, and some examples of the science that follows from this, as well as some of the available software tools that are currently being developed. © 2025 The Author(s). Published by IOP Publishing Ltd.

关键词： Local density approximation

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Interactive particle visualization with advanced shading models using lazy evaluation

Interactive particle visualization with advanced shading mod...

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7th Eurographics Symposium on Parallel Graphics and Visualization, EGPGV 2007

作者： Gribble, Christiaan P. Parker, Steven G. Visual Simulation Group Department of Computer Science Grove City College Scientific Computing and Imaging Institute School of Computing University of Utah United States

ISBN: (纸本)9783905673500

Particle-based simulation methods are used to model a wide range of complex phenomena and to solve time-dependent problems of various scales. Effective visualizations of the resulting state will communicate subtle changes in the three-dimensional structure, spatial organization, and qualitative trends within a simulation as it evolves. We describe a visualization process targeting upcoming, highly parallel multicore desktop systems that enables interactive navigation and exploration of large particle datasets rendered with illumination effects from advanced shading models. These expensive illumination effects are evaluated lazily by decoupling interactive display and high quality rendering. We explore the performance characteristics of this approach and demonstrate its effectiveness using several large particle datasets. © The Eurographics Association 2007.

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Robust parallel ILU preconditioning techniques for solving large sparse matrices 16

Robust parallel ILU preconditioning techniques for solving l...

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16th International Parallel and Distributed Processing Symposium, IPDPS 2002

作者： Shen, Chi Zhang, Jun Laboratory for High Performance Scientific Computing and Computer Simulation Department of Computer Science University of Kentucky 773 Anderson Hall LexingtonKY40506-0046 United States

ISBN: (纸本)0769515738

We discuss issues related to domain decomposition and multilevel preconditioning techniques which are often employed for solving large sparse linear systems in parallel computations. We implement a parallel preconditioner for solving general sparse linear systems based on a two level block ILU factorization strategy. We give some new data structures and strategies to construct a local coefficient matrix and a local Schur complement matrix on each processor. The preconditioner constructed is fast and robust for solving certain large sparse matrices. Numerical experiments show that our domain based two level block ILU preconditioners are more robust and more efficient than some published ILU preconditioners based on Schur complement techniques for parallel sparse matrix solutions. © 2002 IEEE.

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Jigsaw Self-Supervised Visual Representation Learning: An Applied Comparative Analysis Study 2

Jigsaw Self-Supervised Visual Representation Learning: An Ap...

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2nd International Mobile, Intelligent, and Ubiquitous computing Conference, MIUCC 2022

作者： Kawashti, Yomna A. Khattab, Dina Aref, Mostafa M. Ain Shams University Computer Science Department Faculty of Computer and Information Sciences Cairo Egypt Ain Shams University Faculty of Computer and Information Sciences Scientific Computing Department Cairo Egypt

ISBN: (纸本)9781665466776

Self-supervised learning has been gaining momentum in the computer vision community as a hopeful contender to replace supervised learning. It aims to leverage unlabeled data by training a network on a proxy task and using transfer learning for a downstream task. Jigsaw is one of the proxy tasks used for learning better feature representations in self-supervised learning. In this work, we comparably evaluated the transferability of jigsaw using different architectures and a different dataset for jigsaw training. The features extracted from each convolutional block were evaluated using a unified downstream task. The best performance was achieved by the shallower architecture of AlexNet where the 2nd block achieved better transferability with a mean average precision of 36.17. We conclude that this behavior could be attributed to the smaller scale of our used dataset, so features extracted from earlier and shallower blocks had higher transferability to a dataset of a different domain. © 2022 IEEE.

关键词： Training Representation learning Visualization Transfer learning Supervised learning computer architecture Feature extraction

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