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Achievement of essentially full spatial coherence in a high-average-power soft-x-ray laser

Physical Review A 2001年第3期63卷 033802-033802页

作者： Y. Liu M. Seminario F. G. Tomasel C. Chang J. J. Rocca D. T. Attwood Applied Science and Technology Graduate Program University of California Berkeley California 94720 Center for X-ray Optics Lawrence Berkeley National Laboratory Berkeley California 94720 Department of Electrical and Computer Engineering Colorado State University Fort Collins Colorado 80523 Department of Electrical Engineering and Computer Science University of California Berkeley California 94720

We report an observation of essentially full spatial coherence in a high average power soft-x-ray laser. Rapid coherence buildup due to strong refractive antiguiding in a long plasma column is experimentally demonstrated. This allows the generation of fully coherent, milliwatt-level average power soft-x-ray radiation by a tabletop device. The peak brightness of this laser reaches 2×1025photonss−1mm−2mrad−2 within 0.01% spectral bandwidth, making it one of the brightest soft-x-ray sources available.

关键词： .full spatial high average coherence buildup plasma column degree of spatial

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The complexity of the matrix eigenproblem 99

The complexity of the matrix eigenproblem

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Proceedings of the thirty-first annual ACM symposium on Theory of Computing

作者： Victor Y. Pan Zhao Q. Chen Department of Mathematics & Computer Science Lehman College CUNY Bronx NY Ph.D. Program in Math. Graduate Center CUNY New York NY

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A distributed environment for hypercube computing

A distributed environment for hypercube computing

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Aizu International Symposium on Parallel Algorithms/Architecture Synthesis

作者： Jung-Sing Jwo Shi-Sen Chang Yi-Cheng Chen D.F. Hsu Department of Computer and Information Sciences Tunghai University Taichung Taiwan Graduate Program in Computer Science Fordham University New York NY USA

Proposes a distributed computing environment, called the Virtual Cube (VC), to support arbitrarily large binary hypercube computing on a cluster of homogeneous workstations that are interconnected by an Ethernet LAN. The embedding concept between binary hypercube parallel architectures is introduced, and the concept of a cluster of computers interconnected through a computer network. In VC, a SIMD parallel language called VCPL (VC Parallel Language) is provided. The advantages of the VC system are that (a) it can be considered as a practical and economical binary hypercube machine, and (b) it brings parallel solutions on a binary hypercube directly into distributed applications. Currently, a VC prototype is implemented on NeXT workstations.

关键词： Hypercubes Distributed computing Virtual colonoscopy Workstations LAN interconnection computer networks Parallel languages Ethernet networks Local area networks Parallel architectures

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Analysis of product codes for frequency-hopped spread-spectrum with partial band interference

Analysis of product codes for frequency-hopped spread-spectr...

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MILCOM, Military Communications Conference

作者： T.C. Nolan W.E. Stark Department of Defense graduate fellowship program Focused Research Initiative agreement Ann Arbor MI USA Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

A jamming game is considered. A transmitter encodes the data, in a product code (PC), and transmits it in a slow frequency-hopped spread-spectrum (FHSS) system. A hostile jammer attempts to block correct packet reception by adjusting the fraction of the total band in which it distributes the jam power, /spl rho/. Two cases are considered. In the first case, the transmitter declares his strategy and the jammer uses this information to select his best jamming fraction. In the second case, the jammer declares his strategy first and the transmitter uses this information to select his best rates. Results are obtained using asymptotic analysis of a product code using singly extended Reed-Solomon (RS) row and column codes whose size grows large. This asymptotic analysis leads to good choices of the row and column rates for the PC in both cases.

关键词： Product codes Spread spectrum communication Interference Jamming Decoding Error correction codes Frequency shift keying Error correction Reed-Solomon codes Transmitters

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Influence of human engineering on manning levels and human performance on ships

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NAVAL ENGINEERS JOURNAL 1997年第5期109卷 67-76页

作者： Anderson, DE Oberman, FR Malone, TB Baker, CC David E. Anderson:has a bachelor of science degree in environmental engineering from Florida Technological University and a master's degree in environmental engineering from the University of Central Florida. He is a graduate of the Naval Sea Systems Command's Engineer-In-Training (EIT) Program. Mr. Anderson was instrumental in introducing the collective protection system (CPS) in the U.S. Navy developing the initial forward-fit package for the USS Gunston Hall and the engineering change proposal (ECP) for the USS Wasp. In 1990 he joined the Human Systems Integration (HSI) Division (SEA 55W5) where he was task leader for auxiliary ships. He is currently the HSI manager for the future technology variant of the SeaLift ship and the future carrier. Association of Scientists and Engineers 33rdAnnual Technical Symposium 26 April 1996. Fred R. Oberman:has B.A. and M.A. degrees from the University of Chicago and Loyola University (experimental psychology) and an M.S. degree in industrial engineering and operations research from Virginia Polytechnic Institute (VPI). He has more than 30 years experience in HSI management planning research analysis design and testing in government and private sector positions. He is currently responsible for NavSea HSI generic research and tool development efforts. He is responsible for Human Engineering Specifications and Standards (Commercial Hypertext) and is the NavSea 03D7 representative on HSI in Performance Specifications and for integration of HSI within Integrated Logistic Support (ILS). He has served as DoD HSI SubTAG chair and member of the Simulation and Modeling Test and Evaluation Display and Control Systems Human Computer Interaction Specifications and Standards and Systems Design Sub Tags as a member of the Society of Naval Architects and Marine Engineers (SNAME) Systems Safety Panel and a member of NATO RSG 14 on man-machine analysis. Thomas B. Malone: CHFEP received a Ph.D. in experimental psychology from Fordham University in 1964. He is president of Carlow

The objectives of Human Engineering (HE) are generally viewed as increasing human performance, reducing human error, enhancing personnel and equipment safety, and reducing training and related personnel costs. There are other benefits that are thoroughly consistent with the direction of the Navy of the future, chief among these is reduction of required numbers of personnel to operate and maintain Navy ships. The Naval Research Advisory Committee (NRAC) report on Man-Machine Technology in the Navy estimated that one of the benefits from increased application of man-machine technology to Navy ship design is personnel reduction as well as improving system availability, effectiveness, and safety The objective of this paper is to discuss aspects of the human engineering design of ships and systems that affect manning requirements, and impact human-performance and safety The paper will also discuss how the application of human engineering leads to improved performance, and crew safety, and reduced workload, all of which influence manning levels. Finally, the paper presents a discussion of tools and case studies of good human engineering design practices which reduce manning.

关键词： Human engineering

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PERMUTATION ROUTING AND SORTING ON MESHES WITH ROW AND COLUMN BUSES

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Parallel Processing Letters 1995年第1期5卷 63-80页

作者： TORSTEN SUEL Department of Computer Science University of Texas at Austin Austin TX 78712 USA Supported by the Texas Advanced Research Program under Grant Nos. #003658–480 and #003658–461 and by a Schlumberger Graduate Fellowship.

We study the problems of permutation routing and sorting on several models of meshes with fixed and reconfigurable row and column buses. We describe two fast and fairly simple deterministic algorithms for permutation routing on two-dimensional networks, and a more complicated algorithm for multi-dimensional networks. The algorithms are obtained by converting two known off-line routing schemes into deterministic routing algorithms, and they can be implemented on a variety of different models of meshes with buses. We also give a deterministic algorithm for 1–1 sorting whose running time matches that for permutation routing, and another algorithm that matches the bisection lower bound on reconfigurable networks of arbitrary constant dimension.

关键词： Parallel algorithms routing sorting reconfigurable mesh mesh buses

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Synthetic Ethology and the Evolution of Cooperative Communication

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Adaptive Behavior 1993年第2期2卷 161-188页

作者： Maclennan, Bruce J. Burghardt, Gordon M. Computer Science Department University of Tennessee Knoxville TN 37996 United States Psychology Department and Graduate Program in Ethology University of Tennessee Knoxville TN 37996 United States

Synthetic ethology is proposed as a means of conducting controlled experiments investigating the mechanisms and evolution of communication. After a discussion of the goals and methods of synthetic ethology, two series of experiments are described based on at least 5000 breeding cycles. The first demonstrates the evolution of cooperative communication in a population of simple machines. The average fitness of the population and the organization of its use of signals are compared under three conditions: communication suppressed, communication permitted, and communication permitted in the presence of learning. Where communication is permitted, the fitness increases approximately 26 times faster than when communication is suppressed;with communication and learning, the rate of fitness increase is nearly 100-fold The second series of experiments illustrates the evolution of a syntactically simple language, in which a pair of signals is required for effective communication. © 1993, Sage Publications. All rights reserved.

关键词： artificial life communication cooperation entropy ethology evolution genetic algorithm intentionality language learning synthetic ethology

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Book reviews

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Minds and Machines 1993年第3期3卷 335-375页

作者： Erwin M. Segal Meredith Williams David J. Cole James Geller Yorick Wilks Shoshana Loeb Kim Sterelny Jerry Fodor Sara Heinämaa Ausonio Marras Department of Psychology and Center for Cognitive Science State University of New York at Buffalo Buffalo USA Department of Philosophy Northwestern University Evanston USA Department of Philosophy University of Minnesota Duluth USA Department of Computer and Information Science New Jersey Institute of Technology Newark USA Computing Research Laboratory New Mexico State University Las Cruces USA Bell Communications Research Morristown USA Department of Philosophy Victoria University of Wellington Wellington New Zealand Department of Philosophy Rutgers University New Brunswick USA Philosophy Program CUNY Graduate Center New York USA Department of Philosophy University of Helsinki Helsinki Finland Department of Philosophy University of Western Ontario London Canada

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Fast approximation algorithms for multicommodity flow problems 91

Fast approximation algorithms for multicommodity flow proble...

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23rd Annual ACM Symposium on Theory of Computing, STOC 1991

作者： Leighton, Tom Makedont, Fillia Plotkin, Serge Steins, Clifford Tardost, Eva Tragoudas, Spyros Department of Mathematics and Laboratory for Computer Science MIT CambridgeMA United States Computer Science Program University of Texas at Dallas RichardsonTX75083 United States Deparment of Computer Science StanfordCA United States Laboratories Graduate Fellowship MIT CambridgeMA02139 United States School of Operations Research Cornell University IthacaNY United States Computer Science Program University of Texas at Dallas RichardsonTX75063 United States

ISBN: (纸本)0897913973

All previously known algorithms for solving the multicommodity flow problem with capacities are based on linear programming. The best of these algorithms [14] uses a fast matrix multiplication algorithm and takes O(k25n2m5 log(nDU)) time to find an approximate solution, where κ is the number of commodities, n and m denote the number of nodes and edges in the network, D is the largest demand, and U is the largest edge capacity. Substantially more time is needed to find an exact solution. As a consequence, even multicommodit y flow problems with jnst a few commodities are believed to be much harder than single-commodity maximum-flow or minimum-cost flow problems. In thk paper, we describe the first polynomial-Time combinatorial algorithms for approximately solving the multicommodity flow problem. The running time of our randomized algorithm is (up to ,log factors) the same as the time needed to solve κ single-commodity flow problems, thus giving the surprising result that approximately computing a κ-commodity maximum-flow is not much harder than computing about κ single-commodity maximum-flows in isolation. In fact, we prove that a (simple) κ-commodity flow problem can be approximately solved by approximately solving O(κ log2 n) single-commodity minimum-cost flow problems. Our κ-commodity algorithm runs in O(knm log4 n) time with high probability. We also describe a deterministic algorithm that uses an O(κ)-factor more time. Given any multicommodit y flow problem as input, both rdgorithms are guaranteed to provide a feasible solution to a modified fIOW problem in which all capacities are increased by a (1 + c)-factor, or to provide a proof that there is no feasible solution to the original problem. We also describe faster approximation algorithms for multicommodity flow problems with a special structure, such as those that arise in the 'sparsest cutn problems studied in [8, 10, 9], and the uniform concurrent flow problems studied in [13, 9] if κ ≥ √m. © 1991 ACM.

关键词： Approximation algorithms

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FIELD SAMPLING OF RESIDUAL AVIATION GASOLINE IN SANDY SOIL

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GROUND WATER MONITORING AND REMEDIATION 1991年第2期11卷 107-120页

作者： OSTENDORF, DW LEACH, LE HINLEIN, ES XIE, YF 1 David W. Ostendorf is an associate professor in the Environmental Engineering Program of the Civil Engineering Department at the University of Massachusetts (Civil Engineering Department University of Massachusetts Amherst MA 01003). His research interests include unconfined aquifer contamination hazardous waste site remediation and analytical modeling of problems in environmental fluid mechanics. Dr. Ostendorf is a registered professional engineer in Massachusetts and a member of the American Geophysical Union American Society of Civil Engineers Soil Science Society of America Water Pollution Control Federation and Association of Environmental Engineering Professors as well as the National Water Well Association.2 Lowell E. Leach is an environmental engineer with the Robert S. Kerr Environmental Research Laboratory of the U.S. Environmental Protection Agency (RS Kerr Environmental Research Laboratory U.S. EPA P.O. Box 1198 Ada OK74820). Leach received his B.S. ingeological engineering at the University of Oklahoma in 1959 and has been a registered professional engineer in Oklahoma since 1966. With 29 years of experience in field applications of geological engineering he is responsible for developing methodology for sampling ground water and subsurface materials for the Robert S. Kerr Environmental Research Laboratory.3 Erich S. Hinlein is a research assistant in the Environmental Engineering Program of the Civil Engineering Department at the University of Massachusetts (Civil Engineering Department University of Massachusetts Amherst MA 01003). His research interests include ground water pollution hazardous waste site investigation and transport processes in unconfined aquifers. Hinlein graduated with a B.S. in electrical and computer engineering from the University of Massachusetts at Amherst in May 1985 and entered the Environmental Engineering Master's Degree Program in January 1989.4 Yuefeng Xie is a postdoctoral research associate in the Environmental Engineering Program of the Civil E

Two complementary field sampling methods for the determination of residual aviation gasoline content in the contaminated capillary fringe of a fine, uniform, sandy soil were investigated. The first method featured field extrusion of core barrels into pint-size Mason jars, while the second consisted of laboratory partitioning of intact stainless steel core sleeves. The barrel extrusion procedure involved jar headspace sampling in a nitrogen-filled glove box, which delineated the 0.7m thick residually contaminated interval for subsequent core sleeve withdrawal from adjacent boreholes. Soil samples removed from the Mason jars (in the field) and sleeve segments (in the laboratory) were subjected to methylene chloride extraction and gas chromatographic analysis to compare their aviation gasoline content. The barrel extrusion sampling method yielded a vertical profile with 0.10m resolution over an essentially continuous 5.0m interval from the ground surface to the water table. The sleeve segment alternative yielded a more resolved 0.03m vertical profile over a shorter 0.8m interval through the capillary fringe. The two methods delivered precise estimates of the vertically integrated mass of aviation gasoline at a given horizontal location, and a consistent view of the vertical profile as well. In the latter regard, a 0.2m thick lens of maximum contamination was found in the center of the capillary fringe, where moisture filled all voids smaller than the mean pore size. The maximum peak was resolved by the core sleeve data, but was partially obscured by the barrel extrusion observations, so that replicate barrels or a half-pint Mason jar size should be considered for data supporting vertical transport analyses in the absence of sleeve partitions.

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