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Eulerian method for computing multivalued solutions of the Euler-Poisson equations and applications to wave breaking in klystrons

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Physical Review E 2004年第1期70卷 016502-016502页

作者： Xiantao Li John G. Wöhlbier Shi Jin John H. Booske The Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA Department of Electrical and Computer Engineering University of Wisconsin Madison Wisconsin 53706 USA Department of Mathematics University of Wisconsin Madison Wisconsin 53706 USA

We provide methods of computing multivalued solutions to the Euler-Poisson system and test them in the context of a klystron amplifier. An Eulerian formulation capable of computing multivalued solutions is derived from a kinetic description of the Euler-Poisson system and a moment closure. The system of the moment equations may be closed due to the special structure of the solution in phase space. The Eulerian moment equations are computed for a velocity modulated electron beam, which has been shown by prior Lagrangian theories to break in a finite time and form multivalued solutions. The results of the Eulerian moment equations are compared to direct computation of the kinetic equations and a Lagrangian method also developed in the paper. We use the Lagrangian formulation for the explicit computation of wave breaking time and location for typical velocity modulation boundary conditions.

关键词： Klystrons

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Alternating Direction Finite Element Method for a Class of Moving Boundary Problems

Lecture Notes in Computer Science (including subseries Lectu...

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Lecture Notes in computer science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2004年 3314卷 44-50页

作者： Liu, Xu-Zheng Cui, Xia Yong, Jun-Hai Sun, Jia-Guang Department of Computer Science and Technology Tsinghua University Beijing 100084 China Laboratory of Computational Physics Institute of Applied Physics Computational Mathematics Beijing 100088 China School of Software Tsinghua University Beijing 100084 China

An alternating direction finite element scheme for a class of moving boundary problems is studied. Using coordinate transformations of the spatial variants, a new domain independent of the time is obtained and an ADFE scheme on the new domain is proposed. Then the unique solvability of the approximation scheme is proved, and optimal H1 and L2 norm space estimates and O((Δt)2) estimate for the temporal variant are obtained. © Springer-Verlag 2004.

关键词： Finite element method

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Space-time signaling based on Kerdock and Delsafte-Goethals codes

Space-time signaling based on Kerdock and Delsafte-Goethals ...

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IEEE International Conference on Communications (ICC)

作者： A.R. Calderbank S.N. Diggavi N. Al-Dhahir Program in Applied and Computational Mathematics Princeton University Princeton NJ USA School of Computer and Communication Sciences Swiss Federal Institute of Technology Lausanne Switzerland Department of Electrical Engineering University of Technology Dallas TX USA

This paper designs space-time codes for standard PSK and QAM signal constellations that have flexible rate, diversity and require no constellation expansion. Central to this construction are binary partitions of the PSK and QAM constellations that appear in codes designed for the Gaussian channel. The space-time codes presented here are designed by separately specifying the different levels of the binary partition in the space-time array. The individual levels are addressed by either the binary symmetric matrices associated with codewords in a Kerdock code or other families of binary matrices. Binary properties of these sets are sufficient to verify the diversity property of the codewords in the complex domain. Larger sets of binary symmetric matrices (such as the set used in Delsarte-Goethals codes) are used to trade diversity protection for increased rate.

关键词： Space time codes Phase shift keying Quadrature amplitude modulation Constellation diagram Symmetric matrices Binary phase shift keying Quadrature phase shift keying Transmitting antennas Fading mathematics

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Diversity-embedded space-time codes

Diversity-embedded space-time codes

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IEEE Conference and Exhibition on Global Telecommunications (GLOBECOM)

作者： S.N. Diggavi N. Al-Dhahir A.R. Calderbank School of Computer and Communication Sciences Swiss Federal Institute of Technology Lausanne Switzerland Department of Electrical Engineering University of Technology Dallas TX USA Program in Applied and Computational Mathematics Princeton University Princeton NJ USA

Rate and diversity impose a fundamental trade-off in space-time coding. High-rate space-time codes come at a cost of lower diversity, and high reliability (diversity) implies a lower rate. We explore a different point of view where we design high-rate space-time codes that have a high-diversity code embedded within them. This allows a form of communication where the high-rate code opportunistically takes advantage of good channel realizations whereas the embedded high-diversity code ensures that at least part of the information is received reliably. We explore this point of view with design issues, along with some preliminary progress on code constructions and some information-theoretic considerations.

关键词： Space time codes Rayleigh channels Costs Transmitting antennas Transmitters Space technology mathematics Wireless communication Error probability Time division multiplexing

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computational study of turbulent mixing at the Caltech ASC center

Computational study of turbulent mixing at the Caltech ASC c...

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16th AIAA computational Fluid Dynamics Conference 2003

作者： Hill, D. Mattner, T.W. Pantano, C. Cook, A.W. Dimotakis, P.E. Meiron, D.I. Pullin, D.I. GALCIT Caltech 205-45 Pasadena CA 91125 United States GALCIT Caltech 301-46 Pasadena CA 91125 United States Lawrence Livermore National Laboratory Livermore CA 94550 United States Applied and Computational Mathematics and Computer Science Caltech 256-80 Pasadena CA 91125 United States GALCIT Caltech 105-50 Pasadena CA 91125 United States

ISBN: (纸本)9781624100864

We present an overview of a portion of the compressible turbulence program associated with the ASC-sponsored Center for Simulation of Dynamic Response in Materials. Progress in several areas will be summarized. The first is the development of a hybrid WENO-centered-finite-difference method suitable for the large-eddy simulation (LES) of the strong-shock, Richtmyer-Meshkov (RM) instability in a rectangular tube, with end-wall shock reflection and reshock of the evolving mixing layer. The use of this scheme together with a structure-based SGS model for LES of RM instability will be outlined. Second, results obtained from DNS simulations of nonpremixed turbulent combustion in a three-dimensional jet will be described. These were done with finite-rate chemistry using the four-step reduced mechanism of Peters. The emphasis is on diagnostics relating to statistical analysis of flame geometry and turbulent mixing across the range of scales. Lastly, we present results obtained from DNS of Rayleigh-Taylor instability. They elucidate the physics of the gravity-driven mixing through analysis of PDFs of mole fraction and scalar dissipation, and show the structure of the scalar-dissipation field, amplified through the incorporation and extensions of level-set analysis. © 2003 by the authors.

关键词： Large eddy simulation

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Human systems integration and advanced technology in engineering department workload and manpower reduction

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NAVAL ENGINEERS JOURNAL 2003年第1期115卷 57-65页

作者： Lively, KA Seman, AJ Kirkpatrick, M KENNETH A. LIVELY graduated from the University of Colorado with a BS in applied mathematics and an MS in mathematics in 1976 and from the Massachusetts Institute of Technology with an MS in electrical engineering and the degree ocean engineer in naval architecture and marine engineering in 1984. He retired from the U.S. Navy in 1989 after 23 years of service. Assignments included electrical officer on the USS Constellation (CV 64) project engineer for the DDG 51 machinery control system (NAVSEA) and DDG 51 Technical Director (NAVSEA). He was vice president of the PDI Division of Bird-Johnson Company from July 1989 to November 1998 where he managed various gas turbine and machinery controls related development projects. He joined Anteon Corporation's Systems Engineering Group as senior controls engineer in December 1998 where he provided technical support to the integrated power systems program (NAVSEA PMS 510) and managed the Office of Naval Research Afloat Laboratory. DR. MARK KIRKPATRICK is currently an independent consultant in human factors and work-load/manning analysis and modeling. He holds a Ph.D. degree in experimental psychology from The Ohio State University and has 34 years of experience in applied human factors. From 1982 through 2000 Dr. Kirkpatrick served as the senior vice president of Carlow International. Prior to joining Carlow in 1982 Dr. Kirkpatrick served as a member of the technical staff at North American Rockwell's Missiles Division and as a project director and vice president for Essex Corporation. His areas of expertise include workload simulation task analysis operator-in-the-loop simulation human performance experimentation statistical analysis and human factors T&E. He has directed and/or participated in human factors projects for the U.S. Navy U.S. Army NASA Department of Transportation the U.S. Nuclear Regulatory Commission and private industry. ANTHONY J. SEMAN III is the technical manager for the reduced ship's crew by virtual presence (RSVP) advanced technology d

Aboard current ships, such as the DDG 51, engineering control and damage control activities are manpower intensive. It is anticipated that, for future combatants, the workload demand arising from operation of systems under conditions of normal steaming and during casualty response will need to be markedly reduced via automated monitoring, autonomous control, and other technology initiatives. Current DDG 51 class ships can be considered as a manpower baseline and under Condition III typical engineering control involves seven to eight watchstanders at manned stations in the Central Control Station, the engine rooms and other machinery spaces. In contrast to this manning level, initiatives such as DD 21 and the integrated engineering plant (IEP) envision a partnership between the operator and the automation system, with more and more of the operator's functions being shifted to the automation system as manning levels decrease. This paper describes some human systems integration studies of workload demand reduction and, consequently, manning reduction that can be achieved due to application of several advanced technology concepts. Advanced system concept studies in relation to workload demand are described and reviewed including. Piecemeal applications of diverse automation and remote control technology concepts to selected high driver tasks in current DDG 51 activities. Development of the reduced ship's crew by virtual presence system that will provide automated monitoring and display to operators of machinery health, compartment conditions, and personnel health. The IEP envisions the machinery control system as a provider of resources that are used by various consumers around the ship. Resource needs and consumer priorities are at all times dependent upon the ship's current mission and the availability of equipment pawnbrokers.

关键词： Naval warfare

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TSP cuts which do not conform to the template paradigm 5th

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5th International Conference on Mobile Agents, MA 2001

作者： Applegate, David Bixby, Robert Chvátal, Vašek Cook, William Algorithms and Optimization Department AT and T Labs – Research Florham ParkNJ07932 United States Computational and Applied Mathematics Rice University HoustonTX77005 United States Department of Computer Science Rutgers University PiscatawayNJ08854 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States

ISBN: (纸本)3540428771

The first computer implementation of the Dantzig-Fulkerson- Johnson cutting-plane method for solving the traveling salesman problem, written by Martin, used subtour inequalities as well as cutting planes of Gomory’s type. The practice of looking for and using cuts that match prescribed templates in conjunction with Gomory cuts was continued in computer codes of Miliotis, Land, and Fleischmann. Gr¨otschel, Padberg, and Hong advocated a different policy, where the template paradigm is the only source of cuts;furthermore, they argued for drawing the templates exclusively from the set of linear inequalities that induce facets of the TSP polytope. These policies were adopted in the work of Crowder and Padberg, in the work of Gr¨otschel and Holland, and in the work of Padberg and Rinaldi;their computer codes produced the most impressive computational TSP successes of the nineteen eighties. Eventually, the template paradigm became the standard frame of reference for cutting planes in the TSP. The purpose of this paper is to describe a technique for finding cuts that disdains all understanding of the TSP polytope and bashes on regardless of all prescribed templates. Combining this technique with the traditional template approach was a crucial step in our solutions of a 13,509-city TSP instance and a 15,112-city TSP instance. © Springer-Verlag Berlin Heidelberg 2001.

关键词： Traveling salesman problem

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TWO ALGORITHMS FOR LC^1 UNCONSTRAINED OPTIMIZATION

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Journal of computational mathematics 2000年第6期18卷 621-632页

作者： Wen-yu Sun R.J.B.de Sampaio Jin-Yun Yuan School of Mathematics and Computer Science Nanjing Normal UniversityNanjing 210097China Applied Informatics Program Pontifical Catholic University of ParanaCuritibaPR81611-970Brazil Department of Mathematics Federal University of ParanaCuritibaPR81531-990Brazil

Presents two algorithms for LC unconstrained optimization problems which use the second order Dini upper directional derivative. Simplicity of the methods to use and perform; Discussion of related properties of the it... 详细信息

关键词： nonsmooth optimization directional derivative Newton-like method convergence trust region method

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A trace bound for the hereditary discrepancy 00

A trace bound for the hereditary discrepancy

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Proceedings of the sixteenth annual symposium on computational geometry

作者： Bernard Chazelle Alexey Lvov Department of Computer Science Princeton University and NEC Research Institute Program in Applied and Computational Mathematics Princeton University

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Spectra analysis for macromolecular systems: Chain-length effects in polymer particles

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Journal of Polymer science 2000年第13期38卷

作者： Kazuhiko Fukui Bobby G. Sumpter Donald W. Noid Chao Yang Robert E. Tuzun Chemical and Analytical Sciences Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831-6197 Computer Science and Mathematics Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831-6367 Computational Science Program Brockport New York 14420

A complete set of frequencies for the density of states spectrum g(ω) is obtained for 6000-atom polymer particles involving all 18,000 degrees of freedom. We efficiently generate the particle using molecular dynamics and molecular mechanics, and systematically analyze the spectra and thermal properties as a function of chain lengths: from one to 100 monomers. The density of states spectrum g(ω) shows a higher number of low-frequency modes for the polymer particle with a smaller chain length, which results in a higher heat capacity at low temperature. Gibbs free energy was also calculated for the formation of a particle from a crystal as a function of temperature to evaluate thermal stability of those systems. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1812–1823, 2000

关键词： polymer particle normal mode analysis density of state heat capacity Gibbs free energy

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