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International Conference on Acoustics, Speech, and signal processing (ICASSP)

作者： R.A. Nobakht S.H. Ardalan D.E. Van den Bout Center of Communications and Signal Processing Department of Electrical and Computer Engineering North Carolina State University Raleigh NC USA Dept. of Electr. & Comput. Eng. North Carolina State Univ. Raleigh NC USA

A technique for adaptive filtering of nonlinear systems with memory has been developed which combines quantized mean field annealing (QMFA) and conventional recursive-least-squares/fast-transversal filter (RLS/FTF) adaptive filtering. Unlike other methods which rely on Volterra and Wiener models, this technique can efficiently handle large order nonlinearities with or without memory. The nonlinear channel is divided into a memory nonlinearity followed by a dispersive linear system. Assuming that the dispersive linear system is stationary during initialization and the nonlinearity does not change while the dispersive linear system varies with time, QMFA is applied to obtain the coefficients and the order of the memory of the nonlinearity and RLS/FTF is applied to determine the weights of the dispersive linear system. This method was applied to a full duplex digital subscriber loop. Simulations show that the performance of the technique is superior to that of ordinary RLS/FTF and steepest descent algorithms.< >

关键词： Adaptive filters Nonlinear systems Dispersion Linear systems Resonance light scattering Simulated annealing Random access memory Convergence signal processing algorithms Least squares approximation

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Fixed-point roundoff error analysis of the RLS algorithm with time-varying channels

Fixed-point roundoff error analysis of the RLS algorithm wit...

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International Conference on Acoustics, Speech, and signal processing (ICASSP)

作者： T. Adali S.H. Ardalan Dept. of Electr. & Comput. Eng. North Carolina State Univ. Raleigh NC USA Center of Communications and Signal Processing Department of Electrical and Computer Engineering North Carolina State University Raleigh NC USA

The authors derive the steady-state mean square prediction error expression for the fixed-point RLS (recursive least squares) algorithm for the case of time-varying channel estimation, which is modeled as a first-order Markov tapped delay line. It is shown that the random variable driving the time-varying system taps affects the prediction error in the same way as does the roundoff error term due to weight update. It causes the error to grow linearly with time when the forgetting factor, lambda , is chosen as 1. For lambda <1, the excess error tends to increase when the data are correlated. However, this effect is not direct as in the cases of the additive noise and the roundoff error due to the desired signal estimate.< >

关键词： Roundoff errors Error analysis Algorithm design and analysis Resonance light scattering Steady-state Least squares approximation Time-varying channels Delay estimation Recursive estimation Predictive models

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Electromagnetic imaging of dynamic brain activity

Electromagnetic imaging of dynamic brain activity

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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： J. Mosher P. Lewis J. Lewine J. George R. Leahy M. Singh Univ. of Southern California Los Angeles CA USA Mechanical & Electronic Engineering Division Los Alamos National Laboratory Los Alamos NM USA Signal & Image Processing Institute Department Electrical Engineering-Systems University of Southern California Los Angeles CA USA Department of Radiology University of Southern California Los Alamos CA USA

Neural activity in the brain produces weak dynamic electromagnetic fields that can be measured by an array of sensors. Using a spatiotemporal modeling framework, a novel approach to localization of multiple neural sources has been developed. This approach is based on the MUSIC algorithm originally developed for estimating the direction of arrival of signals impinging on a sensor array. The authors present applications of this technique to magnetic field measurements of a phantom and of a human evoked somatosensory response. The results of the somatosensory localization are mapped onto the brain anatomy obtained from magnetic resonance images.< >

关键词： Brain Sensor arrays Magnetic field measurement Magnetic sensors Electromagnetic fields Electromagnetic measurements Spatiotemporal phenomena Multiple signal classification Direction of arrival estimation Imaging phantoms

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ON THE COMPLEXITY OF HYPERELLIPTIC DISCRETE LOGARITHM PROBLEM

ON THE COMPLEXITY OF HYPERELLIPTIC DISCRETE LOGARITHM PROBLE...

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WORKSHOP ON THE THEORY AND APPLICATION OF CRYPTOGRAPHIC TECHNIQUES

作者： SHIZUYA, H ITOH, T SAKURAI, K Department of Electrical Communications Faculity of Engineering Tohoku University Aramaki-Aza-Aoba Aoba-ku Sendai 980 Japan Département d’I.R.O. Université de Montréal C.P.6128 Succ.A Montréal H3C 3J7 QC Canada Department of Information Processing The Graduate School at Nagatsuta Tokyo Institute of Technology 4259 Nagatsuta Midori-ku Yokohama 227 Japan Computer & Information Systems Laboratory Mitsubishi Electric Corporation 5-1-1 Ofuna Kamakura 247 Japan

ISBN: (纸本)3540546200

We give a characterization for the intractability of hyperelliptic discrete logarithm problem from a viewpoint of computational complexity theory. It is shown that the language of which complexity is equivalent to that of the hyperelliptic discrete logarithm problem is in NP ∩ co-AM, and that especially for elliptic curves, the corresponding language is in NP ∩ co-NP. It should be noted here that the language of which complexity is equivalent to that of the discrete logarithm problem defined over the multiplicative group of a finite field is also characterized as in NP ∩ co-NP. © Springer-Verlag Berlin Heidelberg 1991.

关键词： Computational complexity

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Sub-100 mn p+/n junction formation using plasma immersion ion implantation

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Nuclear Inst. and Methods in Physics Research, B 1991年第1-4期55卷 821-825页

作者： Qian, X.Y. Cheung, N.W. Lieberman, M.A. Current, M.I. Chu, P.K. Harrington, W.L. Magee, C.W. Botnick, E.M. Plasma Assisted Materials Processing Laboratory Department of Electrical Engineering and Computer Sciences University of California Berkeley CA 94720 United States Applied Materials Inc. Santa Clara CA 95054 Implant Division: MS0907 3050 Bowers Ave. United States Charles Evans and Associates Redwood City CA 94063 301 Chesapeake Drive United States Evans East Inc. The Office Center Plainsboro NJ 08536 666 Plainsboro Road Suite 1236 United States

Using plasma immersion ion implantation (PIII), sub-100 nm p+/n junctions were fabricated with SiF4 preamorphization followed by BF3 doping. With this technique, the dose rate can be as high as 1016/cm2 per second. Th...

Using plasma immersion ion implantation (PIII), sub-100 nm p⁺/n junctions were fabricated with SiF₄ preamorphization followed by BF₃ doping. With this technique, the dose rate can be as high as 10¹⁶/cm² per second. The silicon wafer was immersed in SiF₄ or BF₃ plasma and biased with a negative voltage. The positively charged ions were accelerated by the electric field in the plasma sheath and implanted into the wafer. The junction depth can be controlled by varying the negative voltage applied to the wafer holder and thermal annealing conditions. © 1991.

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FULL-WAVE SOLUTION OF DIELECTRIC LOADED WAVE-GUIDES AND SHIELDED MICROSTRIPS UTILIZING FINITE-DIFFERENCE AND THE CONJUGATE-GRADIENT METHOD

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INTERNATIONAL JOURNAL OF MICROWAVE AND MILLIMETER-WAVE computer-AIDED engineering 1991年第4期1卷 346-357页

作者： NARAYANAN, V MANELA, M LADE, RK SARKAR, TK Department of Electrical and Computer Engineering Syracuse University Syracuse New York 13244-1240 Viswanathan Narayanan was born in Bangalore India on December 14 1965. He received the BE degree in Electronics and Communications from B.M.S. College of Engineering Bangalore in 1988. He joined the Department of Electrical Engineering at Syracuse University for his graduate studies in 1989 where he is currently a research assistant. His research interests are in microwave measurements numerical electromagnetics and signal processing. Biographies and photos are not available for M. Manela and R. K. Lade. Tapan K. Sarkar (Sf69-M'76-SM'X1) was born in Calcutta. India on August 2 1948. He received the BTech degree from the Indian Institute of Technology Kharagpur India in 1969 the MScE degree from the University of New Brunswick Fredericton Canada in 1971. and the MS and PhD degrees from Syracuse University. Syracuse NY in 1975. From 1975-1976 he was with the TACO Division of the General Instruments Corporation. He was with the Rochester Institute of Technology (Rochester NY) from 1976-1985. He was a Research Fellow at the Gordon Mckay Laboratory Harvard University Cambridge MA from 1977 to 1978. He is now a Professor in the Department of Electrical and Computer Engineering Syracuse University. His current research interests deal with numerical solutions of operator equations arising in electromagnetics and signal processing with application to system design. He obtained one of the “ best solution” awards in May 1977 at the Rome Air Development Center (RADC) Spectral Estimation Workshop. He has authored or coauthored more than 154 journal articles and conference papers and has written chapters in eight books. Dr. Sarkar is a registered professional engineer in the state of New York. He received the Best Paper Award of the IEEE Transactions on Electromagnetic Compatibility in 1979. He was an Associate Editor for feature articles of the lEEE Antennas arid Propagation Sociefy Newsletter and was

Dynamic analysis of waveguide structures containing dielectric and metal strips is presented. The analysis utilizes a finite difference frequency domain procedure to reduce the problem to a symmetric matrix eigenvalue problem. Since the matrix is also sparse, the eigenvalue problem can be solved quickly and efficiently using the conjugate gradient method resulting in considerable savings in computer storage and time. Comparison is made with the analytical solution for the loaded dielectric waveguide case. For the microstrip case, we get both waveguide modes and quasi-TEM modes. The quasi-TEM modes in the limit of zero frequency are checked with the static analysis which also uses finite difference. Some of the quasi-TEM modes are spurious. This article describes their origin and discusses how to eliminate them. Numerical results are presented to illustrate the principles.

关键词： Waveguides

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OPTIMIZATION OF TRANSMITTER AND RECEIVER FILTERS FOR DIGITAL-COMMUNICATION SYSTEMS USING MEAN FIELD ANNEALING

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 1990年第8期8卷 1472-1480页

作者： NOBAKHT, RA VANDENBOUT, DE TOWNSEND, JK ARDALAN, SH Center of Communications and Signal Processing Department of Electrical and Computer Engineering North Carolina State University Raleigh NC USA

A technique for finding transmitter and receiver filters for a wide class of digital communication systems which minimize the bit-error rate (BER) is presented. The technique uses Monte Carlo simulation to estimate the BER and mean field annealing (MFA) to optimize the pulse shapes. Modeling of the link can be as complex as simulation will allow, while MFA is resistant to the statistical variation in the BER estimate from the simulation. Initially, the MFA technique was applied to a binary symmetric channel in a nonsimulation environment, and an approximate analysis of the behavior of MFA for this problem was performed. In a more complex example, MFA was coupled with Monte Carlo simulation techniques to find near-optimal transmit and receive filters for a satellite communications link, taking 6 CPU hours on a DECstation 3100. The BER of the link was found to be as much as three orders of magnitude lower when using the MFA-constructed optimal filters than when using filters from other comparison results. For this example, the pulse shapes obtained using MFA exhibit a low BER even as the parameter controlling the nonlinearity of the satellite-link model is varied over a wide range, thus showing the solution is robust.< >

关键词： Transmitters Digital filters Bit error rate Pulse shaping methods Shape control Digital communication Simulated annealing Performance analysis Satellite communication Robust control

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A REDUCED EDGE DISTORTION MEDIAN FILTERING ALGORITHM FOR BINARY IMAGES

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signal processing 1990年第1期21卷 37-47页

作者： BOLES, WW KANEFSKY, M SIMAAN, M Signal Processing and Interpretation Laboratory Department of Electrical Engineering University of Pittsburgh Pittsburgh PA 15261 U.S.A.

The repeated application of a median filtering algorithm is an effective tool for smoothing images, i.e., filtering additive random and impulsive noises, while preserving edge information. A certain degree of distortion, however, is introduced by such a filter. In images that can be modeled as objects in a homogeneous background, such distortion occurs mostly on object boundaries and generally depends on the type of algorithm (standard, regular recursive, modified recursive, etc.) used to implement the median filter. While these distortions are statistically similar, the question arises as to whether there exist other implementations of a repeated median filter which achieve the same degree of smoothing but consistently yield less edge distortion. In this paper we show the existence of one such implementation for binary images. Using a test image, we demonstrate that our algorithm yields an output image which is significantly closer to the original image than the outputs of the repeated standard or regular recursive algorithms. The performance of our algorithm combines the smoothing capability of a repeated median filter which uses the same window, and the edge preserving property of one which uses a smaller window. Die wiederholte Medianfilterung ist ein wirksames Werkzeug zur Bildglättung, d.h., zur Filterung additiven Zuffalsrauschens wie impulsartiger Störungen. Kanteninformation bleibt dabei erhalten. Eine solche Filterung wird jedoch eine gewisse Verzerrung verursachen. In Bildern, die als Objekte vor homogenem Hintergrund modellhaft beschrieben werden können, treten solche Verzerrungen im wesentlichen an den Objektgrenzen auf und hängen im allgemeinen von der Art des Algorithmus ab (Standardverfahren, reguläres oder modifiziertes rekursives Verfahren usw.), der die Medianfilterung realisiert. Alle diese Verzerrungen sind im statistichen Sinne ähnlich. Es erhebt sich aber die Frage, ob es andersartige Realisierungen wiederholter Medianfilterung gibt, welche ei

关键词： Binary images median filtering root of a median filter edge distortion

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THE COMPLEX CEPSTRUM AND BICEPSTRUM - ANALYTIC PERFORMANCE EVALUATION IN THE PRESENCE OF GAUSSIAN-NOISE

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IEEE TRANSACTIONS ON ACOUSTICS SPEECH AND signal processing 1990年第7期38卷 1246-1256页

作者： PETROPULU, AP NIKIAS, CL Communication and Digital Signal Processing Center for Research and Graduate Studies Department of Electrical and Computer Engineering Northeastern University Boston MA USA

An analytic performance evaluation of the complex cepstrum, power cepstrum, bicepstrum, and power bicepstrum is presented by providing approximate expressions of the bias and variance of the cepstrum parameters due to the presence of Gaussian noise. The approximations are based on the asymptotic properties of bispectrum estimates, and they are valid for moderate signal-to-noise ratios (SNRs). The assumed model consists of a deterministic signal (e.g. multiple echoes) in additive white Gaussian noise and finite length data. The validity of the analytic expressions is verified with Monte Carlo simulations. Performance comparisons between bicepstrum and cepstrum methods suggest that the improved performance of the bicepstrum is a function of SNR, A( omega ), M, and N.< >

关键词： Cepstrum Cepstral analysis Performance analysis Gaussian noise signal to noise ratio signal analysis Additive noise Delay effects Noise measurement Spectral analysis

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DESIGN OF LINEAR-PHASE FIR NOTCH FILTERS

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SADHANA-ACADEMY PROCEEDINGS IN engineering SCIENCES 1990年第3期15卷 133-155页

作者： YU, TH MITRA, SK BABIC, H Signal and Image Processing Laboratory Department of Electrical and Computer Engineering University of California at Santa Barbara Santa Barbara USA Electrotechnical Faculty University of Zagreb Zagreb Yugoslavia

This paper investigates some approaches for designing one-dimensional linear phase finite-duration impulse-responses (FIR) notch filters, which are based on the modification of several established design techniques of linear phase FIR band-selective filters. Based on extensive design examples and theoretical analysis, formulae have been developed for estimating the length of a linear phase FIR notch filter meeting the given specifications. In addition, the design of two-dimensional linear phase FIR notch filters is briefly considered. Illustrative examples are included.

关键词： FIR DIGITAL FILTER DIGITAL FILTER DESIGN DIGITAL NOTCH FILTER

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