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Optimal and approximate station placement in networks (With applications to multicasting and space efficient traversals) 18th

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18th Annual Symposium on Theoretical Aspects of computer Science, STACS 2001

作者： Galdi, Clemente Kaklamanis, Christos Montangero, Manuela Persiano, Pino Dipartimento di Informatica ed Applicazioni Università di Salerno BaronissiSA84081 Italy Computer Technology Institute Dept. of Computer Engineering and Informatics University of Patras Rio26500 Greece

ISBN: (纸本)9783540416951

In this paper we study the k-station placement problem (k- SP problem, in short) on graphs. This problem has application to efficient multicasting in circuit-switched networks and to space efficient traversals. We show that the problem is NP-complete even for 3-stage graphs and give an approximation algorithm with logarithmic approximation ratio. Moreover we show that the problem can be solved in polynomial time for trees. © Springer-Verlag Berlin Heidelberg 2001.

关键词： Approximation algorithms

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Unsupervised video object segmentation algorithm based on moving region tracking

Unsupervised video object segmentation algorithm based on mo...

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Proceedings of the 22nd Picture Coding Symposium: PCS-2001

作者： Cho, Hong K. Lim, Jung Eun Ra, Jong Beom Division of Electrical Engineering Dept. of Elec. Eng./Computer Science Korea Adv. Inst. of Sci./Technology Taejon 305-701 Korea Republic of

In this work, we address an issue of automatically segmenting video objects based on moving region tracking. The proposed algorithm gradually combines moving regions, and tries to automatically determine a whole moving object. Since the algorithm handles an object region-by-region, it preserves the object contour that has strong correlation in a spatio-temporal sense. Experimental results show the proposed algorithm can provide prospective results for automatic video object segmentation and tracking.

关键词： Image segmentation

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Coupling between finite ground coplanar waveguides embedded in polyimide layers for 3D-MMICs on Si

Coupling between finite ground coplanar waveguides embedded ...

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2001 31st European Microwave Conference, EuMC 2001

作者： Ponchak, George E. Papapolymerou, John Tentzeris, Emmanoui M. NASA Glenn Research Center Cleveland OH 44135 United States Dept. of Electrical and Computer Engineering University of Arizona Tucson AZ 85721 United States School of Electrical and Computer Engineering Georgia Inst. of Technology Atlanta GA 30332 United States

Three-dimensional circuits built upon multiple layers of polyimide are required for constructing Si/SiGe monolithic microwave/mm-wave integrated circuits on low resistivity Si wafers. However, the closely spaced transmission lines are susceptible to high levels of cross-coupling, which degrades the overall circuit performance. In this paper, theoretical and experimental results on coupling of Finite Ground Coplanar (FGC) waveguides embedded in polyimide layers are presented for the first time. These results show that FGC lines have approximately 8 dB lower coupling than coupled Coplanar Waveguides. Furthermore, it is shown that the forward and backward coupling characteristics for FGC lines do not resemble the coupling characteristics of other transmission lines such as microstrip. © 2001 IEEE.

关键词： Coplanar waveguides

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A model-based Q-learning scheme for wireless channel allocation with prioritized handoff

A model-based Q-learning scheme for wireless channel allocat...

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IEEE Global Telecommunications Conference GLOBECOM'01

作者： El-Alfy, El-Sayed Yao, Yu-Dong Heffes, Harry Wireless Systems Engineering Lab Dept. of Elec. and Computer Eng. Stevens Inst. of Tech. Hoboken NJ 07030-5991 United States

In this paper we propose a new channel allocation scheme for improving the quality of service in cellular mobile networks. The proposed algorithm prioritizes handoff call requests over new call requests. The goal is to reduce the handoff failures while still making efficient use of the network resources. A performance measure is formed as a weighted linear function of new call and handoff call blocking probabilities. This problem is formulated as a semi-Markov decision process with an average cost criterion. A simulation-based learning algorithm is then developed to approximate the optimal control policy online using the generated samples from direct interactions with the network. It is based on an approximate model that is estimated simultaneously while learning a control policy. The estimated model is used to direct the search for an optimum policy. Extensive simulations are provided to assess the effectiveness of the algorithm under a variety of traffic conditions. Comparisons with some well-known allocation policies are also presented. Simulation results show that for the traffic conditions considered in this paper, the proposed scheme has a comparable performance to the optimal guard channel approach.

关键词： Wireless telecommunication systems

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Approximate constrained bipartite edge coloring 1

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27th International Workshop on Graph-Theoretic Concepts in computer Science, WG 2001

作者： Caragiannis, Ioannis Ferreira, Afonso Kaklamanis, Christos Pérennes, Stéphane Persiano, Pino Rivano, Hérve Computer Technology Institute Dept. of Computer Engineering and Informatics University of Patras Rio26500 Greece MASCOTTE Project INRIA Sophia Antipolis 2004 route des Lucioles B.P. 93 Sophia Antipolis Cedex06902 France Dipartimento di Informatica ed Applicazioni Università di Salerno Baronissi84081 Italy

ISBN: (数字)9783540454779

ISBN: (纸本)3540427074

We study the following Constrained Bipartite Edge Coloring (CBEC) problem: We are given a bipartite graph G(U, V, E) of maximum degree I with n vertices, in which some of the edges have been legally colored with c colors. We wish to complete the coloring of the edges of G minimizing the total number of colors used. The problem has been proved to be NP-hard even for bipartite graphs of maximum degree three [5]. In previous work Caragiannis et al. [2] consider two special cases of the problem and proved tight bounds on the optimal number of colors by decomposing the bipartite graph into matchings which are colored into pairs using detailed potential and averaging arguments. Their techniques lead to 3/2-aproximation algorithms for both problems. In this paper we present a randomized (1.37 + o(1))-approximation algorithm for the general problem in the case where max{l,c} = ω(ln n). Our techniques are motivated by recent work of Kumar [11] on the Circular Arc Coloring problem and are essentially different and simpler than those presented in [2]. © Springer-Verlag Berlin Heidelberg 2001.

关键词： Color

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DNA-based computation

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Computing in Science and engineering 2001年第6期3卷 94-99页

作者： Zomaya, Albert Y. Anderson, James A. Fogel, David B. Milburn, Gerard J. Rozenberg, Grzegorz Parallel Comp. Research Laboratory Dept. of Elec. and Electronic Eng. Univ. of Western Australia Nedlands WA 6907 Australia Dept. of Cogn. and Ling. Sciences Brown Univ. Providence RI 02912 United States Natural Selection 3333 N. Torrey Pines Ct. San Diego CA 92037 United States Ctr. for Quantum Computer Technology Dept. of Physics Univ. of Queensland St. Lucia QLD. 4072 Australia Department of Computer Science University of Colorado Boulder CO United States Inst. of Advanced Computer Science Leiden Univ. Niels Bohrweg 1 2333 CA Leiden Netherlands

No abstract available

关键词： DNA computing Biology computing computer science Molecular computing Parallel processing Information processing Biological system modeling computer industry Moore's Law Silicon

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Probabilistic bandwidth reservation by resource priority multiplexing

Probabilistic bandwidth reservation by resource priority mul...

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Real-Time technology and Applications Symposium

作者： J.P. Hansen Haifeng Zhu R. Rajkumar Inst. for Complex Engineered Systems Carnegie Mellon University Pittsburgh PA USA Dept. of Electrical and Computer Engineering Carnegie Mellon University Pittsburgh PA USA Dept. of Electrical and Computer Engineering Carnegie Mellon University Pittsburgh PA

ISBN: (纸本)0769511341

Probabilistic bandwidth guarantees on variable bit-rate network flows offer significant improvements in throughput for only modest decreases in guarantee level. We present a probabilistic bandwidth reservation scheme for variable bit-rate flows called resource priority multiplexing (RPM). The RPM algorithm uses packet marking on edge routers and selective dropping on core routers to provide per-flow specification of probabilistic QoS with guarantees ranging from best-effort to hard reservation. RPM also supports multiple metrics for probabilistic level of service specification. All flow tables are managed only by the edge routers enhancing scalability of the approach. Unlike existing statistical multiplexing approaches, RPM uses a time-multiplexed priority tagging algorithm which provides higher control over flows guarantee levels. The algorithm has been implemented in a live system as part of the IP protocol stack and experimental results are presented.

关键词： Bandwidth Propagation losses Resource management Admission control Contracts computer networks Real time systems Queueing analysis Stochastic systems Next generation networking

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Interactive visual software system for problem solving and teaching in finite group theory

Interactive visual software system for problem solving and t...

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International Conference on Information technology Interfaces

作者： M.M. Kolodnytsky A.M. Koivalchuk S.V. Kuryata V.G. Levitsky Computer Software Department Zhytomyr Institute of Engineering and Technology Zhytomyr Ukraine Ukraine Dept. of Comput. Software Zhytomyr Inst. of Eng. & Technol. Ukraine

ISBN: (纸本)9539676932

The article shows how to solve some computational problems in finite group theory using the software system "DSR Open Lab 1.0" designed and developed by authors. We consider such computational problems as follows: the construction of the group using given elements or a genetic code (generators and relations), the operations with the group elements as well as the calculations of subgroups and their powers, normal subgroup, factor-group, etc. We also give a comparison of the user interface implementation of our software with Maple V Release 5. The presented examples show that the process of problem solving and teaching in finite group theory has become easier and more interactive now, due to the visual user interface of the presented software.

关键词： Software systems Problem-solving Education Content addressable storage Genetics Power generation User interfaces Software tools Algebra Packaging

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Gaussian pixel weighting marks in amplitude modulation of color image watermarking

Gaussian pixel weighting marks in amplitude modulation of co...

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International Symposium on Signal Processing and Its Applications (ISSPA)

作者： R. Puenpan T. Amornraksa Comput. Eng. Dept. King Mongkut's Inst. of Technol. Bangkok Thailand Computer Engineering Department King Mongkut's University of Technology Thonburi Bangkok Thailand

A watermark embedding method, using an amplitude modulation technique, based on Gaussian pixel-weighting marks is proposed. The method utilizes a technique of weighting a mark by averaging the luminance of its own pixel and its neighboring pixels, and uses it as an additional scaling factor in existing watermark embedding methods. The watermark retrieval process is borrowed from the technique of image averaging from the cross-shaped neighboring pixels of the watermarked image, and hence has no need of the original image. The results show that improved performance is obtained when applying the Gaussian pixel-weighting marks technique, compared to other techniques, namely the equal gain pixel-weighting and the no pixel-weighting marks techniques.

关键词： Pixel Amplitude modulation Color Watermarking Image retrieval Robustness PSNR Brightness Quantization Streaming media

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An efficient approach for distributed channel allocation in cellular mobile networks 01

An efficient approach for distributed channel allocation in ...

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Proceedings of the 4th International Workshop on Discrete Algorithms and Methods for Mobile Computing and Communications

作者： Zhang, Yongbing Jia, Xiaohua Das, Sajal K. Inst. of Plcy. and Planning Sciences University of Tsukuba Tsukuba Ibaraki 305-8573 Japan Department of Computer Science City University of Hong Kong Tat Chee Ave. Kowloon Hong Kong Dept. of Comp. Sci. and Engineering University of Texas at Arlington Arlington TX 76203-1366 United States

ISBN: (纸本)1581134215

We propose a distributed channel allocation algorithm based on a threshold scheme, called D-CAT, for cellular mobile networks. The D-CAT algorithm employs two thresholds: (i) a heavy threshold used for determining whether a cell is heavy, i.e., overloaded, and for triggering the channel allocation algorithm;and (ii) a target threshold used for indicating the target number of free channels that a heavy cell intends to acquire. We determine the optimal number of free channels as welt as the cell(s) from where a heavy cell should import to satisfy its channel demand. Simulation experiments and analyses show that the D-CAT algorithm incurs lower overhead for channel allocation and is more efficient in terms of channel utilization than other distributed channel allocation algorithms. It also outperforms other centralized and distributed algorithms in terms of call blocking probability.

关键词： Telecommunication networks

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