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American Society of Mechanical Engineers, Material Handling division, MHD 1999年 5卷 191-199页

作者： Freitag, Lori Urness, Tim Math. and Computer Science Division Argonne National Laboratory Argonne IL 60439 United States Scientific Visualization Laboratory 1003 Cowley Hall University of Wisconsin - La Crosse La Crosse WI 54601 United States Argonne National Laboratory

We describe an interactive toolkit used to perform comparative analysis of two or more data sets arising from numerical simulations. Several techniques have been incorporated into this toolkit, including (1) successive visualization of individual data sets, (2) data comparison techniques such as computation and visualization of the differences between data sets, and (3) image comparison methods such as scalar field height profiles plotted in a common coordinate system. We describe each technique in detail and show example usage in an industrial application aimed at designing an efficient, low-NOx burner for industrial furnaces. Critical insights are obtained by interactively adjusted color maps, data culling, and data manipulation. New paradigms for scaling small values in the data comparison technique are described. The display device used for this application was the CAVE virtual reality theater, and we describe the user interface to the visualization toolkit and the benefits of immersive 3D visualization for comparative analysis.

关键词： Virtual reality

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Globus project: a status report

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Future Generation computer Systems 1999年第5期15卷 607-621页

作者： Foster, Ian Kesselman, Carl Math. and Computer Science Division Argonne National Laboratory 9700 S. Cass Avenue Argonne IL 60439 United States Information Sciences Institute University of Southern California Marina del Rey CA 90292-6695 United States University of California Los Angeles CA United States

The Globus project is a multi-institutional research effort that seeks to enable the construction of computational grids providing pervasive, dependable, and consistent access to high-performance computational resources, despite geographical distribution of both resources and users. Computational grid technology is being viewed as a critical element of future high-performance computing environments that will enable entirely new classes of computation-oriented applications, much as the World Wide Web fostered the development of new classes of information-oriented applications. In this paper, we report on the status of the Globus project as of early 1998. We describe the progress that has been achieved to date in the development of the Globus toolkit, a set of core services for constructing grid tools and applications. We also discuss the Globus Ubiquitous Supercomputing Testbed Organization (GUSTO) that we have constructed to enable large-scale evaluation of Globus technologies, and we review early experiences with the development of large-scale grid applications on the GUSTO testbed.

关键词： Distributed computer systems

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Angular-metric traveling salesman problem

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SIAM Journal on Computing 1999年第3期29卷 697-711页

作者： Aggarwal, Alok Coppersmith, Don Khanna, Sanjeev Motwani, Rajeev Schieber, Baruch IBM Research Division T.J. Watson Research Center Yorktown Heights NY 10598 United States Fundamental Math. Res. Department Bell Labs. 700 Mountain Avenue Murray Hill NJ 07974 United States Department of Computer Science Stanford University Stanford CA 94305 United States

Motivated by applications in robotics, we formulate the problem of minimizing the total angle cost of a TSP tour for a set of points in Euclidean space, where the angle cost of a tour is the sum of the direction changes at the points. We establish the NP-hardness of both this problem and its relaxation to the cycle cover problem. We then consider the issue of designing approximation algorithms for these problems and show that both problems can be approximated to within a ratio of O(log n) in polynomial time. We also consider the problem of simultaneously approximating both the angle and the length measure for a TSP tour. In studying the resulting tradeoff, we choose to focus on the sum of the two performance ratios and provide tight bounds on the sum. Finally, we consider the external value of the angle measure and obtain essentially tight bounds for it. In this paper we restrict our attention to the planar setting, but all our results are easily extended to higher dimensions.

关键词： Traveling salesman problem

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On the nonexistence of quaternary [51, 4, 37] codes

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Finite Fields and their Applications 1996年第1期2卷 96-110页

作者： Landgev, I. Maruta, T. Hill, R. Institute of Mathematics 1113 Sofia 8 Acad. G. Bonchev str Bulgaria Meijo University Junior College Division Tenpaku Nagoya Japan Dept. of Math. and Computer Science University of Salford Salford M5 4WT United Kingdom

In this paper we prove the nonexistence of quaternary linear codes with parameters [51, 4, 37]. This result gives the exact value of nq(k, d) for q = 4, k = 4, d = 37 and 38. These were the only minimum distances for ...

In this paper we prove the nonexistence of quaternary linear codes with parameters [51, 4, 37]. This result gives the exact value of n_q(k, d) for q = 4, k = 4, d = 37 and 38. These were the only minimum distances for which the optimal length of a four-dimensional quaternary code was unknown. The proof is geometrical and relies heavily on results about the structure of certain sets of points in PG(2, 4). © 1996 Academic Press, Inc.

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Automated Discovery of Active Motifs in Multiple RNA Secondary Structures 2

Automated Discovery of Active Motifs in Multiple RNA Seconda...

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2nd International Conference on Knowledge Discovery and Data Mining, KDD 1996

作者： Wang, Jason T. L. Shapiro, Bruce A. Shasha, Dennis Zhang, Kaizhong Chang, Chia-Yo Computer and Information Sci. Dept. New Jersey Institute of Technology NewarkNJ07102 United States Division of Basic Sciences National Institutes of Health FrederickMD21702 United States Courant Institute of Math. Sciences New York University New YorkNY10012 United States Computer Science Dept. University of Western Ontario London OntarioN6A 5B7 Canada

ISBN: (纸本)1577350049

In this paper we present a method for discovering approximately common motifs (also known as active motifs) in multiple RNA secondary structures. The secondary structures can be represented as ordered trees (i.e., the order among siblings matters). Motifs in these trees are connected subgraphs that can differ in both substitutions and deletions/insertions. The proposed method consists of two steps: (1) find candidate motifs in a small sample of the secondary structures;(2) search all of the secondary structures to determine how frequently these motifs occur (within the allowed approximation) in the secondary structures. To reduce the running time, we develop two optimization heuristics based on sampling and pattern matching techniques. Experimental results obtained by running these algorithms on both generated data and RNA secondary structures show the good performance of the algorithms. To demonstrate the utility of our algorithms, we discuss their applications to conducting the phylogenetic study of RNA sequences obtained from GenBank. © 1996 AAAI (***). All Rights Reserved.

关键词： RNA

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Design of storage hierarchy in multithreaded architectures 28

Design of storage hierarchy in multithreaded architectures

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Proceedings of the 28th annual international symposium on Microarchitecture

作者： Lucas Roh Walid A. Najjar Math. & Computer Science Division Argonne National Laboratory Argonne IL Department of Computer Science Colorado State University Fort Collins CO

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Design of storage hierarchy in multithreaded architectures

Design of storage hierarchy in multithreaded architectures

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IEEE/ACM International Symposium on Microarchitecture (MICRO)

作者： L. Roh W.A. Najjar Math. & Computer Science Division Argonne National Laboratory Argonne IL USA Department of Computer Science Colorado State University Fort Collins CO USA

Multithreaded execution models attempt to combine some aspects of dataflow-like execution with von Neumann model execution. Their main objective is to mask the latency of inter-processor communications and remote memory accesses in large scale multiprocessors. An important issue in the analysis and evaluation of multithreaded execution is the design and performance of the storage hierarchy. Because of the sequential execution of threads, the locality of access within an executing thread can be exploited using registers and cache. At the inter-thread level, however, the locality of accesses to memory and its effect on the cache is not yet well understood. A storage model which can exploit this locality is developed and evaluated. The results indicate there is a large amount of inter-thread locality that can be exploited and that we can get an efficient storage system by exploiting the characteristics of nonblocking threads.

关键词： Yarn Multithreading computer science Delay Switches Costs computer architecture Laboratories Large-scale systems Registers

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Free bits, PCPs and non-approximability-towards tight results

Free bits, PCPs and non-approximability-towards tight result...

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Annual IEEE Symposium on Foundations of computer science

作者： M. Bellare O. Goldreich M. Sudan Department of Computer Science & Engineering University of California San Diego La Jolla CA USA Computer Science and Applied Math. Department Weizmann Institute of Science Rehovot Israel IBM Research Division IBM Thomas J. Watson Research Center Yorktown Heights NY USA

The first part of this paper presents new proof systems and improved non-approximability results. In particular we present a proof system for NP using logarithmic randomness and two amortized free bits, so that Max clique is hard within N/sup 1/3/ and chromatic number within N/sup 1/5/. We also show hardness of 38/37 for Max-3-SAT, 27/26 for vertex cover, 82/81 for Max-cut, and 94/93 for Max-2-SAT. The second part of this paper presents a "reverse" of the FGLSS connection by showing that an NP-hardness result for the approximation of Max clique to within a factor of N/sup 1/(g+1/) would imply a probabilistic verifier for NP with logarithmic randomness and amortized free-bit complexity g. We also show that "existing techniques" won't yield proof systems of less than two bits in amortized free bit complexity. Finally, we initiate a comprehensive study of PCP and FPCP parameters, proving several triviality results and providing several useful transformations.

关键词： computer science Postal services Drives Cities and towns Error correction codes Polynomials History

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Parallelizing a global atmospheric chemical tracer model

Parallelizing a global atmospheric chemical tracer model

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Scalable High Performance Computing Conference

作者： J. Demmel S. Smith Computer Science Division & Math. Department University of California Berkeley CA USA Computer Science Division University of California Berkeley CA USA

We describe the design of a parallel global atmospheric chemical tracer model. This is part of a larger Earth Systems Model (ESM) for atmospheric dynamics and physics, and ocean physics. The ESM will be used for global warming and ozone depletion studies, among others. The goal is to parallelize the chemistry model to run efficiently on current and future parallel architectures, including the Sequoia archival database. We describe the preliminary design, especially the detailed timing model, and some initial validations. We have found a timing modeling very valuable for designing for a large range of architectures.< >

关键词： Chemicals Atmospheric modeling Physics Timing Earth Oceans Global warming Chemistry Parallel architectures Databases

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Scalable heterogeneous programming tools

Scalable heterogeneous programming tools

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1995 Heterogeneous Computing Workshop, HCW 1994

作者： Chen, Song Eshaghian, Mary M. Freund, Richard F. Potter, Jerry L. Wu, Ying-Chieh Department of Computer and Information Science New Jersey Institute of Technology NewarkNJ07102 United States RDT and E Division Naval Command Control and Ocean Surveillance Center San DiegoCA92152 United States Department of Math. and Computer Science Kent State University KentOH44242 United States

ISBN: (纸本)0818655925

In this paper, we study the heterogeneous use of two programming paradigms for heterogeneous computing called Cluster-M and HAsC. Both paradigms can efficiently support heterogeneous networks by preserving a level of abstraction which does not include any architecture mapping details. Furthermore, they are both machine independent and hence are scalable. Unlike, almost all existing heterogeneous orchestration tools which are MIMD based, HAsC is based on the fundamental concepts of SIMD associative computing. HAsC models a heterogeneous network as a coarse grained associative computer and is designed to optimize the execution of problems with large ratios of computations to instructions. Ease of programming and execution speed, not the utilization of idle resources are the primary goals of HAsC. On the other hand, Cluster-M is a generic technique that can be applied to both coarse grained as well as fine grained networks. Cluster-M provides an environment for porting various tasks onto the machines in a heterogeneous suite such that resources utilization is maximized and the overall execution time is minimized. We illustrate how these two paradigms can be used together to provide an efficient medium for heterogeneous programming. Finally, their scalability is discussed. © 1994 IEEE.

关键词： Heterogeneous networks

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