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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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A novel key management scheme for dynamic access control in a user hierarchy

A novel key management scheme for dynamic access control in ...

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IEEE Annual International Computer Software and Applications Conference (COMPSAC)

作者： Tzer-Shyong Chen Yu-Fang Chung Chang-Sin Tian Department of Information Management Tunghai University Taiwan Department of Electrical Engineering National Taiwan University of Science and Technology Taiwan Department of Applied Mathematics National Chiayi University Taiwan

ISBN: (纸本)0769522092

Considering the solution of dynamic access problems in a user hierarchy, a novel scheme based on one-way hash function is proposed to manage the cryptographic keys in the paper The scheme attempts to achieve both efficiency and non-iteration in deriving the successor secret key. Besides, the other issues in relation with dynamic access control problems, such as adding/deleting classes, adding/deleting relationships and changing secret keys, can be held good to the scheme. In view of security, a competent central authority must provide the user a convenient way to change his/her key at any time; therefore, the design toward the algorithm in the paper contains such a function. What weight to mention especially among these characteristics of the scheme is the simplification of procedure in changing the private key, and no other current keys need altering simultaneously.

关键词： Access control Data security Cryptography Information security Communication system security engineering management Information management mathematics Algorithm design and analysis Computer networks

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Wavelet galerkin algorithms for ground penetrating radar imaging

Wavelet galerkin algorithms for ground penetrating radar ima...

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Proceedings of the International Conference on Ground Penetrating Radar, GPR

作者： Fengshan Liu Yi Ling Xiquan Shi Xianggen Xia Applied Mathematics Research Center Delaware State University Dover DE USA Department of Electrical and Computer Engineering University of Delaware Newark DE USA

ISBN: (纸本)9090179593

A new algorithm for fixed-offset Ground Penetrating Radar imaging is derived. The forward model of this inversion scheme is based on the Born approximation and the dyadic Green function for a two-layer medium. The forward model is inverted using the Wavelet Galerkin Algorithms for solving integral equations. We use the Laplacian operator to regularize the ill-posedness of the inverse problem. Numerical results are provided to illustrate performance of the inversion scheme.

关键词： Ground penetrating radar Optical imaging Approximation methods Green function Optical scattering Radar scattering Inverse problems Radar imaging Integral equations Laplace equations

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Interior point methods meet simplex in L, fitting problems

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International Transactions in Operational Research 2004年第3期11卷 309-322页

作者： Oliveira, A.R.L. Lyra, C. Applied Mathematics Department State University of Campinas Brazil School of Electrical Engineering and Computer Science State University of Campinas Brazil

Interior point methods specialized to the L∞ fitting problem are surveyed, improved, and compared with the traditional simplex approach. A primal affine-scaling interior point method is presented, completing the affi... 详细信息

Interior point methods specialized to the L_∞ fitting problem are surveyed, improved, and compared with the traditional simplex approach. A primal affine-scaling interior point method is presented, completing the affine-scaling interior point family approach to the L_∞ fitting problem. Computational complexity and data storage are reduced for interior point approaches when dealing with polynomial fitting problems. Numerical experiments indicate that interior point approaches rarely perform better than the simplex method for the tested problems. The primal affine-scaling method presented in this paper achieved the best results among the interior point family. © 2004 Wiley Periodicals, Inc.

关键词： Chebychev norm-based fitting problem Interior point methods L based statistical analysis L∞ curve fitting Linear programming

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International Journal of Adaptive Control and Signal Processing: Editorial

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International Journal of Adaptive Control and Signal Processing 2004年第4期18卷 317-318页

作者： Polderman, Jan Willem Mareels, Iven Department of Applied Mathematics University of Twente P.O.Box 217 7500 AE Enschede Netherlands Department of Electrical Engineering University of Melbourne Vic 3052 Australia

No abstract available

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Growing networks with geographical attachment preference: Emergence of small worlds

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Physical Review E 2004年第2期69卷 026108-026108页

作者： Jonathan Ozik Brian R. Hunt Edward Ott Department of Physics and Institute for Research in Electronics and Applied Physics University of Maryland College Park Maryland 20742 USA Department of Mathematics and Institute for Physical Science and Technology University of Maryland College Park Maryland 20742 USA Department of Physics Department of Electrical and Computer Engineering and Institute for Research in Electronics and Applied Physics University of Maryland College Park Maryland 20742 USA

We introduce a simple mechanism for the evolution of small world networks. Our model is a growing network in which all connections are made locally to geographically nearby sites. Although connections are made purely locally, network growth leads to stretching of old connections and to high clustering. Our results suggest that the abundance of small world networks in geographically constrained systems is a natural consequence of system growth and local interactions.

关键词： Computer networks

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Optimization of extrapolated impulse response filters using semi-infinite programming

Optimization of extrapolated impulse response filters using ...

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International Symposium on Communications Control and Signal Processing (ISCCSP)

作者： Ya Jun Yu Guohui Zhao Kok Lay Teo Yong Ching Lim Temasek Laboratories Nanyang Technological University Singapore Applied Mathematics Department Hong Kong Polytechnic University Hong Kong China Electrical & Electronic Engineering Nanyang Technological University Singapore

Narrow band lowpass or highpass digital finite impulse response filters can be synthesized by using extrapolated impulse response techniques to achieve reduced complexity. However, the non-linear optimization problem of the extrapolated impulse response filters was simplified to a linear programming problem in previous literature leading to suboptimum. In this paper, a semi-infinite programming is proposed to jointly optimize the filter coefficients and the extrapolated scaling factors. A realization structure making use of the coefficient symmetry is also presented. An example taken from literature is included illustrating that the number of multipliers for the resulting filter is less than 65 percent of existing results.

关键词： Finite impulse response filter Narrowband Mathematical programming Laboratories mathematics Nonlinear filters Linear programming Digital filters Digital signal processing Stability

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Desynchronization Waves and Localized Instabilities in Oscillator Arrays

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Physical Review Letters 2004年第11期93卷 114101-114101页

作者： Juan G. Restrepo Edward Ott Brian R. Hunt Institute for Research in Electronics and Applied Physics University of Maryland College Park Maryland 20742 USA Department of Mathematics University of Maryland College Park Maryland 20742 USA Department of Physics and Department of Electrical and Computer Engineering University of Maryland College Park Maryland 20742 USA Institute for Physical Science and Technology University of Maryland College Park Maryland 20742 USA

We consider a ring of identical or near-identical coupled periodic oscillators in which the connections have randomly heterogeneous strength. We use the master stability function method to determine the possible patterns at the desynchronization transition that occurs as the coupling strengths are increased. We demonstrate Anderson localization of the modes of instability and show that such localized instability generates waves of desynchronization that spread to the whole array. Similar results should apply to other networks with regular topology and heterogeneous connection strengths.

关键词： .week ending arrays DESYNCHRONIZATION coupling strengths periodic oscillators Maryland USA master stability

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Approximating functions using rough sets

Approximating functions using rough sets

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Conference of the North American Fuzzy Information Processing Society - NAFIPS

作者： Z. Pawlak J. Peters A. Skowron Institute of Theoretical and Applied Informatics Polish Academy of Sciences Gliwice Poland Warsaw School of Information Technology Warsaw Poland Department of Electrical and Computer Engineering University of Manitoba Winnipeg MAN Canada Institute of Mathematics University of Warmia and Mazury Warsaw Poland

Approximating of functions that are specified using imperfect knowledge is one of the central issues of many areas such as machine learning, pattern recognition, data mining, or qualitative reasoning. However, we do not have yet satisfactory methods for approximation of functions and developed calculi on function approximations. In the paper we discuss a function approximation using the rough set approach. The main difference with the existing approaches in rough set theory is based on modification of the inclusion measure. This makes it possible to overcome some drawbacks of the previously used definitions. For applications it is important to develop rough measures on approximated objects, in particular on function approximations. The modified inclusion measure is also used to define an exemplary measure, i.e., the rough integral.

关键词： Rough sets Function approximation Information technology Data mining Set theory Particle measurements Extraterrestrial measurements Information systems Informatics mathematics

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Periodicity in Δ-modulated feedback control

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IFAC Proceedings Volumes 2004年第13期37卷 411-416页

作者： X. Xia G. Chen R. Gai A.S. Zinober Department of Electrical Electronic and Computer Engineering University of Pretoria Pretoria 0002 South Africa Department of Electronic Engineering City University of Hong Kong 83 Tat Chee Avenue Kowloon Hong Kong SAR P. R. China Department of Basic Science Liaoning Technical University Fuxin 123000 P. R. China Department of Applied Mathematics The University of Sheffield Sheffield S10 2TN UK

Δ-modulated feedback control of a linear system introduces nonlinearity into the system through switchings between two input values. It has been found that Δ-modulation gives rise to periodic orbits. The existence of periodic points of all orders of Sigma-Delta modulation with “leaky” integration is completely characterized by some interesting groups of polynomials with “sign” coefficients. The results are naturally generalized to Sigma-Delta modulations with multiple delays. Further extensions relate to the existence of periodic points arising from Δ-modulated feedback control of a stable linear system in an arbitrary direction, for which some necessary and sufficient conditions are given.

关键词： switching periodic orbit Δ-modulation sign polynomial nonlinear control

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