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Congress on Evolutionary Computation

作者： Jian Zhang Xiaohui Yuan B.P. Buckles Department of Electrical Engineering and Computer Science Tulane University New Orleans LA USA

Niching techniques diversify the population of evolutionary algorithms, encouraging heterogeneous convergence to multiple optima. The key to an effective diversification is identifying the similarity among individuals. With no prior knowledge of the fitness landscapes, it is usually determined by uninformative assumptions on the number of peaks. We propose a method to estimate the sharing distance and the corresponding population size. Using the probably approximately correct (PAC) learning theory and the e-cover concept, we derive the PAC neighbor distance of a local optimum. Within this neighborhood, uniform samples are drawn and we compute the subspace fitness distance correlation (FDC) coefficients. An algorithm is developed to estimate the granularity feature of the fitness landscapes. The sharing distance is determined from the granularity feature and furthermore, the population size is decided. Experiments demonstrate that by using the estimated population size and sharing distance an evolutionary algorithm (EA) correctly identifies multiple optima.

关键词： Iterative algorithms Loss measurement computer science Convergence Evolutionary computation Pattern recognition Image processing Image converters Focusing Clustering algorithms

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The role of reactivity in multiagent learning

The role of reactivity in multiagent learning

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Proceedings of the International Joint Conference on Autonomous Agents and Multiagent Systems, AAMAS

作者： B. Banerjee Jing Peng Department of Electrical Engineering & Computer Science Tulane University New Orleans LA USA

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A human power conversion system based on children's play

A human power conversion system based on children's play

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International Symposium on Technology and Society (ISTAS)

作者： S.R. Pandian Department of Electrical Engineering and Computer Science Tulane University New Orleans LA USA

A method is proposed for harnessing of human power based on children's play in playground and public places, on devices such as the seesaw, merry-go-round and swing. When large numbers of children play in a playground, part of the power of their play can be usefully harnessed resulting in significant energy storage. This stored energy can then be converted to electricity for powering basic, low-power appliances such as lights, fans, communications equipment, and so on. The method provides a low-cost, low-resource means of generation of electricity, especially for use in developing countries. The paper discusses the basic theory behind the method. Results of experiments on a laboratory prototype compressed air human power conversion system using a teeter-totter are presented to illustrate the practical effectiveness of the proposed method.

关键词： Humans Power conversion Energy storage Energy conversion Home appliances Fans Communication equipment Power generation laboratories Prototypes

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The complexity of the covering radius problem on lattices and codes

The complexity of the covering radius problem on lattices an...

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Annual IEEE Conference on Computational Complexity

作者： V. Guruswami D. Micciancio O. Regev Department of Computer Science University of Washington Seattle WA USA Department of Computer Science and Engineering University of California San Diego La Jolla CA USA Department of Computer Science Tel-Aviv University Tel-Aviv Israel

We initiate the study of the computational complexity of the covering radius problem for point lattices, and approximation versions of the problem for both lattices and linear codes. We also investigate the computational complexity of the shortest linearly independent vectors problem, and its relation to the covering radius problem for lattices. For the covering radius on n-dimensional lattices, we show that the problem can be approximated within any constant factor /spl gamma/(n) > 1 in random exponential time 2/sup O(n)/, it is in AM for /spl gamma/(n) = 2, in coAM for /spl gamma/(n) = /spl radic/(n log n), and in NP /spl cap/ coNP for /spl gamma/(n) = /spl radic/n. For the covering radius on n-dimensional linear codes, we show that the problem can be solved in deterministic polynomial time for approximation factor /spl gamma/(n) = log n, but cannot be solved in polynomial time for some /spl gamma/(n) = /spl Omega/(log log n) unless NP can be simulated in deterministic n/sup O(log log log n)/ time. Moreover, we prove that the problem is NP-hard for every constant approximation factor, it is /spl Pi//sub 2/-hard for some constant approximation factor, and it is in AM for approximation factor 2. So, it is unlikely to be /spl Pi//sub 2/-hard for approximation factors larger than 2. This is a natural hardness of approximation result in the polynomial hierarchy. For the shortest independent vectors problem, we give a coAM protocol achieving approximation factor /spl gamma/(n) = /spl radic/(n/log n), solving an open problem of Blomer and Seifert (1999), and prove that the problem is also in coNP for /spl gamma/(n) = /spl radic/n. Both results are obtained by giving a gap-preserving nondeterministic polynomial time reduction to the closest vector problem.

关键词： lattices Error correction codes computer science Computational complexity Linear code Polynomials Vectors Protocols engineering profession Galois fields

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Cover Picture: An Engineered Virus as a Scaffold for Three-Dimensional Self-Assembly on the Nanoscale (Small 7/2005)

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Small 2005年第7期1卷

作者： Amy Szuchmacher Blum Dr. Carissa M. Soto Dr. Charmaine D. Wilson Tina L. Brower Dr. Steven K. Pollack Dr. Terence L. Schull Dr. Anju Chatterji Dr. Tianwei Lin Prof. John E. Johnson Prof. Christian Amsinck Paul Franzon Prof. Ranganathan Shashidhar Dr. Banahalli R. Ratna Dr. Center for Bio/Molecular Science and Engineering Naval Research Laboratory 4555 Overlook Avenue SW Washington DC 20375 USA Fax: (+1) 202-404-3043 Geo-Centers Inc. Newton MA 02459 USA Department of Molecular Biology The Scripps Research Institute 10550 North Torrey Pines Road La Jolla CA 92037 USA Department of Electrical and Computer Engineering North Carolina State University Raleigh NC 27695 USA Geo-Centers Inc. 4301 North Fairfax Drive Suite 200 Room 248 Arlington VA 22203 USA

The cover picture shows an STM tip measuring the network conductance of a nanosized network built from molecular conductors using programmed self-assembly; a dramatic illustration of the potential of nanoelectronics. Gold nanoparticles are attached to a modified cowpea mosaic virus scaffold. The particles can then be interconnected using thiol-terminated organic molecules, which act as molecular wires. For more information, please read the Communication "An Engineered Virus as a Scaffold for Three-Dimensional Self-Assembly on the Nanoscale" by A. S. Blum and co-workers on page 702 ff.

关键词： molecular electronics nanotechnology protein engineering self-assembly viruses

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Worst-case to average-case reductions based on Gaussian measures

Worst-case to average-case reductions based on Gaussian meas...

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Annual IEEE Symposium on Foundations of computer science

作者： D. Micciancio O. Regev Department of Computer Science and Engineering University of California San Diego La Jolla CA USA Department of Computer Science Tel-Aviv University Tel-Aviv Israel

We show that solving modular linear equation on the average is at least as hard as approximating several lattice problems in the worst case within a factor almost linear in the rank of the lattice. The lattice problems we consider are the shortest vector problem, the shortest independent vectors problem and the covering radius problem. The approximation factor we obtain is O(n) for all three problems. This greatly improves on all previous work on the subject starting from Ajtai's seminal paper (STOC, 1996), up to the strongest previously known results by Micciancio (STOC, 2002). Our results also bring us closer to the limit where the problems are no longer known to be in NP /spl cap/ coNP. Our main tools are Gaussian measures on lattices and the high dimensional Fourier transform. We start by defining a new lattice parameter which determines the amount of Gaussian noise that one has to add to a lattice in order to get close to a uniform distribution, in addition to yielding quantitatively much stronger results, the use of this parameter allows us to simplify many of the complications in previous work. Our technical contributions are two-fold. First, we show tight connections between this new parameter and existing lattice parameters. One such important connection is between this parameter and the length of the shortest set of linearly independent vectors. Second, we prove that the distribution that one obtains after adding Gaussian noise to the lattice has the following interesting property: the distribution of the noise vector when conditioning on the final value behaves in many respects like the original Gaussian noise vector. In particular, its moments remain essentially unchanged.

关键词： lattices Gaussian noise Polynomials computer science Vectors Military computing Cryptography Equations Fourier transforms engineering profession

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Specifying role-based access constraints with object constraint language

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 3007卷 687-696页

作者： Wang, Hua Zhang, Yanchun Cao, Jinli Yang, Jian Department of Maths and Computing University of Southern Queensland Toowoomba QLD 4350 Australia School of Computer Science and Mathematics Victoria University of Technology Melbourne City Vic. MC8001 Australia Department of Computer Science and Computer Engineering La Trobe University Melbourne Vic. 3086 Australia School of Information Technology Swinbourne University of Technology Hawthorn Vic. 3122 Australia

Constraints are an important aspect of role-based access control (RBAC). Constraints have to be satisfied when an administrator wants to assign (revoke) a role to a user or a permission to a role. The importance of constraints associated with user-role assignments and permission-role assignments in RBAC has been recognized but the modelling of these constraints has not been received much attention. In this paper we use a de facto constraints specification language in software engineering to analyze the constraints in user-role assignments and permission-role assignments. We show how to represent role-based access constraints with object constraint language (OCL) and discuss the future work. Finally, comparisons with other related work are presented. © Springer-Verlag Berlin Heidelberg 2004.

关键词： Software engineering

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Clustered multithreaded architectures - pursuing both IPC and cycle time

Clustered multithreaded architectures - pursuing both IPC an...

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International Symposium on Parallel and Distributed Processing (IPDPS)

作者： J.D. Collins D.M. Tullsen Department of Computer Science and Engineering University of California San Diego La Jolla CA USA

Summary form only given. Clustering is an architectural technique that allows the design of wide superscalar processors without sacrificing cycle time, but at the cost of longer communication latencies. Simultaneous multithreading architectures effectively tolerate instruction latency, but put even more pressure on timing-critical processor resources. We show that the synergistic combination of the two techniques minimizes the IPC impact of the clustered architecture, and even permits more aggressive clustering of the processor than is possible with a single-threaded processor. Additionally, we show that multithreading enables effective instruction steering policies unavailable to a single-threaded clustered architecture. We explore the impact of aggressively clustering four complex processor structures, (1) instruction window wakeup and functional unit bypass logic, (2) register renaming logic, (3) the fetch unit, and (4) the integer register file, on a simultaneous multithreading processor.

关键词： Multithreading Delay Costs Logic Clocks Registers Hardware Pipelines Throughput Surface-mount technology

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A flexible architecture for customizing web streams for wireless clients

A flexible architecture for customizing web streams for wire...

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Workshop on Applications and Services in Wireless Networks, ASWN

作者： J. Steinberg J. Pasquale Department of Computer Science and Engineering University of California San Diego La Jolla CA USA

We present the design of the Web Stream Customizer Architecture, the basis for a middleware system that supports customization of Web content and streams. Our notion of customization is quite general, including functions such as mtering, remote buffering, remote caching, flow regulation (e.g., for video playback), compression, and encryption, all of which are especially valuable for wireless resource· limited clients, which are a primary target of support. The system is highly deployable, as it works entirely within the Web's common programming and communication frameworks, such as using HTTP and relying solely on standard proxy mechanisms, and therefore does not require any changes to existing Web servers and browsers.

关键词： Service oriented architecture Streaming media Communication system security Filtering computer architecture Cryptography computer displays Energy consumption Data security Information security

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FastR: fast database search tool for non-coding RNA

FastR: fast database search tool for non-coding RNA

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Proceedings of the IEEE Computational Systems Bioinformatics Conference, CSB

作者： V. Bafna Shaojie Zhang Department of Computer Science and Engineering University of California San Diego La Jolla CA USA

The discovery of novel non-coding RNAs has been among the most exciting recent developments in biology. Yet, many more remain undiscovered. It has been hypothesized that there is in fact an abundance of functional non-coding RNA (ncRNA) with various catalytic and regulatory junctions. Computational methods tailored specifically for ncRNA are being actively developed. As the inherent signal for ncRNA is weaker than that for protein coding genes, comparative methods offer the most promising approach, and are the subject of our research. We consider the following problem: Given an RNA sequence with a known secondary structure, efficiently compute all structural homologs (computed as a function of sequence and structural similarity) in a genomic database. Our approach, based on structural filters that eliminate a large portion of the database, while retaining the true homologs allows us to search a typical bacterial database in minutes on a standard PC, with high sensitivity and specificity. This is two orders of magnitude better than current available software for the problem.

关键词： Databases RNA Sequences Biology computing Proteins Genomics Bioinformatics Filters Microorganisms Sensitivity and specificity

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