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IEEE International Conference on Image Processing

作者： P.J. Sementilli A. Bilgin F. Sheng M.W. Marcellin J.C. Kieffer Science Applications International Corporation Tucson AZ USA Department of Electrical and Computer Engineering University of Arizona Tucson Tucson AZ USA Department of Electrical Engineering University of Minnesota Minneapolis MN USA

As image coders evolve from DCT-based to wavelet-based designs, the latter must be enhanced to include capabilities currently supported by standards such as JPEG. Said and Pearlman (see IEEE Transactions on Circuits and Systems for Video Tech., vol.6, p.243-50, 1996) and Schwartz, Zandi and Boliek (see Proc. of SPIE, vol.2564, July 1995) have described approaches for incorporating progressive transmission capabilities within wavelet-based coders. All of these coders apply scalar quantization to wavelet transform coefficients and then apply sophisticated entropy coding methods to the quantized coefficients. In this paper, we present coding techniques that enable progressive transmission when trellis coded quantization (TCQ) is applied to the wavelet coefficients. While the trellis coded quantizer is more complex than the uniform scalar quantizer, comparable PSNR performance is achieved with a simple entropy coder. In addition, our use of sophisticated quantization and bit rate allocation algorithms enables the development of coders that are tuned for improved perceptual image quality.

关键词： Decoding Quantization Entropy coding Wavelet coefficients Arithmetic PSNR Bit rate Discrete cosine transforms Discrete wavelet transforms Application software

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Hydroelastic considerations in ship panel design

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NAVAL ENGINEERS JOURNAL 1997年第5期109卷 61-66页

作者： McCormick, ME Bhattacharyya, R Mouring, SE Dr. Michael E. McCormick:is a research professor of civil engineering at The Johns Hopkins University. Before joining the Hopkins faculty in 1994 he was a professor of ocean engineering for twenty-five years at the U.S. Naval Academy. In addition he has held full-time faculty positions at Swarthmore College Trinity College (Hartford) and the Catholic University of America. He was also a hydrodynamicist at the David Taylor Model Basin for more than four years. Prof. McCormick received his undergraduate degree in mathematics and physics from AmericanUniversity a masters degree in applied mechanics and a Ph.D. in mechanical engineering from Catholic University a Ph.D. in civil engineering and a Sc.D. in engineering science from Trinity College in Dublin Ireland. He has over 100 publications including two books in the areas of ocean engineering wave mechanics and ocean wave energy conversion. He has also edited two books dealing with ocean engineering. In addition he is co-editor of both the journal Ocean Engineering and the Elsevier book series in ocean engineering. Dr. Rameswar Bhattacharyya:is professor of naval architecture at the U.S. Naval Academy where he has served for twenty-six years and adjunct professor of mechanical engineering at The Johns Hopkins University. Prior to joining the Naval Academy faculty he was a faculty member in the Department of Naval Architecture and Marine Engineering at the University of Michigan. His research experience includes ten years at both the Lubecker Flender-Werke and the Hamburg Ship Model Basin in Germany. His research has led to numerous publications including two books one in the area of ship dynamics and the other in the area of computer-aided ship design. Prof. Bhattacharyya received his undergraduate degree in naval architecture from the Indian Institute of Technology and his doctorate in engineering from the Technical University of Hanover Germany. In addition he holds an honorary doctorate from the University of Veracruz. With Prof. McCormick he co

Panels and all other structural components of surface ships and submarines vibrate when the vessel is underway. The vibratory motions are primarily excited by the power plant. At operational (design) speeds, panels vibrate in their fundamental modes and those associated with their higher harmonic frequencies. The panel motions have rather well-defined energy spectra, which depend on both the structural design, position of the panel and the rotational speed of the single or multiple power plants. The panel motions will interact with the vortices in the adjacent turbulent boundary layer. The interaction can result in either an increase in the frictional drag or a decrease. Because of this, the argument is made that the designs of the panels and their support systems should include considerations of this hydroelastic effect.

关键词： Naval architecture

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Towards a thread-based parallel direct execution simulator 29

Towards a thread-based parallel direct execution simulator

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29th Hawaii International Conference on System sciences, HICSS 1996

作者： Dickens, Phillip Hainesa, Matthew Mehrotraa, Piyush Nicol, David Institute For Computer Applications in Science and Engineering MS 132C NASA Langley Research Center HamptonVA23681 United States Department of Computer Science College of William and Mary WilliamsburgVA 23187 United States

ISBN: (纸本)0818673249

Parallel direct execution simulation is an important tool for performance and scalability analysis of large message passing parallel programs executing on top of a virtual computer. However, detailed simulation of message-passing codes requires a great deal of computation. We are therefore interested in pursuing implementation techniques which can decrease this cost. One idea is to implement the application virtual processes as lightweight threads rather than traditional Unix processes, reducing both on-processor communication costs and context-switching costs. In this paper we describe an initial implementation of a thread-based parallel direct execution simulator. We discuss the advantages of such an approach and present preliminary results that indicate a significant improvement over the process-based approach. © 1996 IEEE

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Analysis of compressible mixing layers using a dilatational covariances model 32nd

Analysis of compressible mixing layers using a dilatational ...

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32nd Joint Propulsion Conference and Exhibit, 1996

作者： Thangam, S. Zhou, Y. Ristorcelli, J.R. Institute for Computer Applications in Science and Engineering NASA Langley Research Center HamptonVA23681 United States Department of Mechanical Engineering Stevens Institute of Technology HobokenNJ07030 United States ICASE United States

Compressible mixing layers are analyzed using a dilatational covariances model based on a pseudo-sound constitutive relation. The calculations are used to evaluate the different physical phenomena affecting compressible mixing layers. The rate of growth of the mixing layer is retarded by both the compressible dissipation and the pressure-dilatational covariances. The pressure-dila-tational, essentially a nonequilibrium effect, reduces the amount of excess production over dissipation available for the turbulence energy growth. The pseudo-sound model also includes a history dependent portion: this is also investigated. All constants in the model and used in these computations are predicted by the theory. © 1996 American Institute of Aeronautics and Astronautics, Inc.

关键词： Mixing

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Schwarz-preconditioned Newton-Krylov algorithm for low speed combustion problems 34th

Schwarz-preconditioned Newton-Krylov algorithm for low speed...

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34th Aerospace sciences Meeting and Exhibit, 1996

作者： McHugh, P.R. Knoll, D.A. Keyes, D.E. Idaho National Engineering Laboratory P.O. Box 1625 Idaho FallsID83415-3808 United States Institute for Computer Applications in Science and Engineering NASA-LaRC HamptonVA23681-0001 United States Department of Computer Science Old Dominion University NorfolkVA23529-0162 United States

Newton-Krylov-Schwarz algorithms solve a system of equations describing low Mach number combustion. Two model problems are considered. The first is a low speed, combusting flow through a channel, representing an idealized laminar diffusion flame. The second problem consists of an expansion channel, representing an idealized combustion chamber. Both problems include three chemical species and one kinetic reaction. Finite-volume discretization on a staggered mesh converts the continuous system of governing equations into a discrete system of nonlinear algebraic equations, which are subsequently linearized using Newton's method. The resulting linearized systems are solved using the preconditioned Generalized Minimal RESidual (GMRES) algorithm. The effectiveness of domainbased additive and multiplicative Schwarz preconditioned is studied with respect to partitioning strategy and subdomain solver selection. Block incomplete factorizations of the subdomain matrices yield effective Schwarz preconditioners with comparatively moderate computer memory requirements. In comparison, point-wise incomplete factorizations are unreliable at low Mach numbers, while complete factorizations often require excessive computer memory. Multiplicative Schwarz preconditioning outperforms additive Schwarz, but not sufficiently so to outweigh the parallel advantages of additive Schwarz. Preconditionng with a low-order discretization reduces both computer memory and CPU time for the Reynolds number of interest. © 1995 by the American Institute of Aeronautics and Astronautics, Inc.

关键词： Newton-Raphson method

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Towards a thread-based parallel direct execution simulator

Towards a thread-based parallel direct execution simulator

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Annual Hawaii International Conference on System sciences (HICSS)

作者： P. Dickens M. Haines P. Mehrotra D. Nicol Institute For Computer Applications in Science and Engineering NASA-Langley Research Center Hampton VA USA Department of Computer Science College of William and Mary VA USA

Parallel direct execution simulation is an important tool for performance and scalability analysis of large message passing parallel programs executing on top of a virtual computer. However, detailed simulation of message-passing codes requires a great deal of computation. We are therefore interested in pursuing implementation techniques which can decrease this cost. One idea is to implement the application virtual processes as lightweight threads rather than traditional Unix processes, reducing both on-processor communication costs and context switching costs. We describe an initial implementation of a thread-based parallel direct execution simulator. We discuss the advantages of such an approach and present preliminary results that indicate a significant improvement over the process-based approach.

关键词： Computational modeling Costs Analytical models computer simulation Scalability Performance analysis Message passing Concurrent computing Application software Yarn

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Experiments in Automated Load Balancing

Experiments in Automated Load Balancing

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Workshop on Principles of Advanced and Distributed Simulation (PADS)

作者： L.F. Wilson D.M. Nicol Institute for Computer Applications in Science and Engineering NASA-Langley Research Center Hampton VA USA Department of Computer Science The College of William and Mary Williamsburg VA USA

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On computing sound radiation of a temporally evolving mixing layer by vortex method and matched asymptotic expansions 34th

On computing sound radiation of a temporally evolving mixing...

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34th Aerospace sciences Meeting and Exhibit, 1996

作者： Hu, F.Q. Martin, J.E. Hussaini, M.Y. Department of Mathematics and Statistics Old Dominion University NorfolkVA23529 United States Department of Mathematics Christopher Newport University Newport NewsVA23606 United States Institute for Computer Applications in Science and Engineering NASA Langley Research Center HamptonVA23681 United States

In this paper, sound radiation associated with a temporally evolving mixing layer is considered. Numerical simulations are carried out by a vortex method in which the mixing layer is modeled by an array of vortex blobs and perturbed with the wavelength of the most amplified wave. Since the vortex method computes an incompressible flow, a methodology of computing the acoustic field based on matched asymptotic expansions is employed. A singular perturbation is developed in which the incompressible solution obtained by the vortex method is the inner solution while the acoustic field is the outer solution. The formal matching process is carried out by introducing intermediate variables. It is shown that in the limit of zero Mach number, the leading terms match smoothly. The inner solution of the incompressible flow..thus provides the boundary condition for the outer solution of radiated sound. Numerical results of the vortex simulation and computed acoustic pressure are presented. © 1996 by the American Institute of Aeronautics and Astronautics, Inc. All Rights Reserved.

关键词： Acoustic fields

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Alternate path reasoning in intelligent instrument fault diagnosis for gas chromatography

Alternate path reasoning in intelligent instrument fault dia...

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IEEE International Joint Symposia on Intelligence and Systems

作者： K.L. Adair S.I. Hruska J.W. Elling Department of Computer Science Florida State University USA Engineering Sciences and Applications-Measurement Technology Los Alamos National Laboratory USA

Intelligent instrument fault diagnosis is addressed using expert networks, a hybrid technique which blends traditional rule-based expert systems with neural network style training. One of the most difficult aspects of instrument fault diagnosis is developing an appropriate rule base for the expert network. Beginning with an initial set of rules given by experts, a more accurate representation of the reasoning process can be found using example data. A methodology for determining alternate paths of reasoning and incorporating them into the expert network is presented. Our technique presupposes interaction and cooperation with the expert, and is intended to be used with the assistance of the expert to incorporate knowledge discovered from the data into the intelligent diagnosis tool. Tests of this methodology are conducted within the problem domain of fault diagnosis for gas chromatography. Performance statistics indicate the efficacy of automating the introduction of alternate path reasoning into the diagnostic reasoning system.

关键词： Instruments Fault diagnosis Gas chromatography Laboratories Intelligent networks Fault detection Knowledge based systems Humans computer science Application software

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Experiments in automated load balancing 96

Experiments in automated load balancing

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Proceedings of the tenth workshop on Parallel and distributed simulation

作者： Linda F. Wilson David M. Nicol Institute for Computer Applications Science and Engineering NASA Langley Research Center Hampton VA Department of Computer Science The College of William and Mary P.O. Box 8795 Williamsburg VA

ISBN: (纸本)9780818675393

One of the promises of parallelized discrete-event simulation is that it might provide significant speedups over sequential simulation. In reality, high performance cannot be achieved unless the system is fine-tuned to balance computation, communication, and synchronization requirements. In this paper, we discuss our experiments in automated load balancing using the SPEEDES simulation framework. Specifically, we examine three mapping algorithms that use run-time measurements. Using simulation models of queuing networks and the National Airspace System, we investigate (i) the use of run-time data to guide mapping, (ii) the utility of considering communication costs in a mapping algorithm, (iii) the degree to which computational ``hot-spots'' ought to be broken up in the linearization, and (iv) the relative execution costs of the different algorithms. We compare the performance of the three algorithms using results from the Intel Paragon.

关键词： load balancing discrete-event simulation parallel computing performance analysis

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