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IEEE Conference on Aerospace Applications

作者： B.R. Mahafza D.L. Knight M.W. Suits N.F. Audeh KBM Enterprises Inc. Huntsville AL USA Materials and Processing Laboratory NASA Marshall Space Flight Center AL USA Electrical and Computer Engineering Department University of Alabama Huntsville Huntsville AL USA

A technique for dynamic real time focusing of ultrasonic transducer arrays is introduced. This paper assumes a linear transducer array operating in the sequential mode. In this case, the elements are fired sequentially, one at a time, all elements receive in parallel. The returns are integrated coherently on the basis of equal geometric phase to synthesize the echoes of an array twice as large. Dynamic focusing is accomplished at any depth through electronic correction of the dominant quadratic phase terms. For this purpose a second order Taylor series expansion of the phase is used.< >

关键词： Ultrasonic transducer arrays Ultrasonic transducers Focusing Phased arrays Ultrasonic imaging Delay effects Logic Image resolution Signal processing Sampling methods

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Instrumentation for the Acoustic Thermometry of Ocean Climate (ATOC) prototype Pacific Ocean network

Instrumentation for the Acoustic Thermometry of Ocean Climat...

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OCEANS

作者： B.M. Howe S.G. Anderson A. Baggeroer J.A. Colosi K.R. Hardy D. Horwitt F.W. Karig S. Leach J.A. Mercer K. Metzger L.O. Olson D.A. Peckham D.A. Reddaway R.R. Ryan R.P. Stein K. von der Heydt J.D. Watson S.L. Weslander P.F. Worcester Applied Physics Laboratory University of Washington Seattle WA USA Massachusetts Institute of Technology Cambridge MA USA Scripps Institution of Oceanography University of California San Diego Seattle WA USA Scripps Institution of Oceanography University of California San Diego La Jolla CA USA Communications and Signal Processing Laboratory Electrical Engineering and Computer Science Department University of Michigan Ann Arbor MI USA Woods Hole Oceanographic Institution Seattle WA USA Applied Physics Laboratory University of Washington Woods Hole MA USA

The prototype Pacific Ocean network for the Acoustic Thermometry of Ocean Climate (ATOC) program consists of two shore-cabled acoustic sources, two autonomous vertical hydrophone receiving arrays, and 16 U.S. Navy hydrophone arrays. The sources, receivers, and signaling strategy are designed to be capable of up to 10-megameter transmissions on a routine basis. A new broadband, low-frequency (75 Hz), acoustic source was designed and built by Alliant Techsystems. The bender-bar/barrel-stave transducer is pressure compensated for operation to 1000-m depth. Signal waveform shaping is employed to broaden the effective bandwidth of the source to 37.5 Hz (Q=2; time resolution of 27 ms). Four-element vertical hydrophone arrays are attached to the sources to permit reciprocal transmissions and ambient noise monitoring. Autonomous vertical hydrophone arrays consisting of 40 elements at 35-m spacing (1400-m aperture) were developed to resolve low-order acoustic modes. The autonomous arrays are designed for deployments of up to 1 year, with intermediate readout of the data via ship-recoverable pop-up data modules. The U.S. Navy hydrophone arrays were instrumented with 80486-based data acquisition and processing systems, with communications links for transmitting the data in near real time to a central site for further processing and archiving.

关键词： Instruments Oceans Sonar equipment Acoustic arrays Prototypes Signal design Acoustic transducers Bandwidth Signal resolution Acoustic noise

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Improvement of convergence speed for subband adaptive digital filter using the multirate repeating method

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ELECTRONICS AND COMMUNICATIONS IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE 1995年第10期78卷 37-45页

作者： Kiya, H Nishikawa, K Ashihara, K Faculty of Technology Tokyo Metropolitan University Hachioji Japan 192-03 Members Kiyoshi Nshikawa graduated in 1990 from the Department of Electrical Engineering Tokyo Metropolitan University where he completed the Master's Program in 1992 and affiliated with Nippon Steel Co. Computer Systems Laboratory. He was a Research Associate in 1993 in the Department of Elect. Inf. Eng. Tokyo Metropolitan University engaged in research onadaptive signal processing and information source coding. He is a member of the IEEE. Associate Member

The subband adaptive system, where the idea of the filter bank is applied to the adaptive filter, has a feature that a higher-order adaptation can be reduced to lower-order adaptations. The reduction of the order of the adaptive filter is related closely to the number of channels and the decimation ratio. The order of adaptive digital filter (ADF) is decreased greatly when the number of subbands is increased, and the decimation ratio is increased up to the maximum value. Then, however, the number of coefficient-updates per unit time is decreased, which results in the deterioration of the convergence Speed. From such a viewpoint, this paper discusses a method to improve the convergence speed, which is deteriorated in the subband adaptive system, due to the decimation. The idea of the proposed method is to utilize effectively the data which have been discarded in the decimation process and to improve the convergence speed. It is called the multirate repeating method. As the first step, the multirate repeating method is applied to the conventional subband adaptive system and the convergence speed is improved. Then a subband adaptive system is introduced in which the multirate repeating method can be utilized more effectively. As a result, a faster convergence is realized while retaining the ADF order-reduction effect, which is an advantage of the subband adaptive system.

关键词： adaptive signal processing subband adaptive system multirate repeating method rational decimation

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Multiagent fault‐diagnosis expert system in power systems

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European Transactions on electrical Power 1995年第5期5卷 341-347页

作者： Wang, J.P. Trécat, J. Dr. Jianping Wang is a doctor fellow in the Faculte Polytechnique de Mons in Belgium. His current research field is parallel processing applications in power systems. Dr. Wang obtained his BS degree from Southwest Jiaotong University in P.R. Chinain 1982. From 1982 to 1990 he was appointed as an assistant lecturer. lecturer and associate professor respectively in the electrical engineering department of Southwest Jiaotong University. He obtained his Ph.D in the FacultC Polytechnique de Mons in July of 1993. (BD Dolez 3 1 FPMS B-7000 Mons Belgium T +32-65/37 41 87 Fax +32-65/37 43 00) Professor J. Trécat is a director in the power system laboratory in the Faculty Polytechnique de Mons. He obtained his Ph.D in the University of Manchester Institute of Science and Technology(UM1ST) in U.K. in 1970. He has been working in the fields of power system automation artificial intelligence application and computer vision in the Facult6 Polytechnique de Mons since 1970. He is a senior member of IEEE and he has made much contribution both in electrical engineering education and research. (BD Dolez 3 I FPMS B-7000 Mons T +32-651374185. Fax +32-6513743 00)

In order to solve the speed problem and shallow reasoning problem met in current research in fault diagnosis expert system, this paper presents a model based parallel fault diagnosis expert system for energy management systems (EMS). The Petri net model, which corresponds to the relationship between power system components and their protection systems, has been used for the inference in fault diagnosis. A multiagent parallel processing expert system, which is based on five transputers in Sun workstation, has been built for fault diagnosis purposes. The test results show that this expert system is not only fast but also has better performances. Copyright © 1995 John Wiley & Sons, Ltd.

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ANALYTICAL MODELING OF PLASMA IMMERSION ION-IMPLANTATION TARGET CURRENT USING THE SPICE CIRCUIT SIMULATOR

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B

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JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B 1994年第2期12卷 833-837页

作者： EN, W CHEUNG, NW Plasma Assisted Materials Processing Laboratory Department of Electrical Engineering and Computer Sciences University of California Berkeley California 94720

Plasma immersion ion implantation applies a series of negative high-voltage pulses to a target immersed in a plasma. An analytical model of the currents and potentials induced before, during, and after the negative bias in a planar geometry is presented. The effect of multiple pulses on the results is also studied. The model determines the time-varying ion current, electron current, total current, total dose, and sheath thickness for a piecewise linear voltage pulse. The sheath collapse is found to be important for high repetition rate pulses. Implementation of the model is done in SPICE, a circuit simulator. Comparison with experimental data has demonstrated the accuracy of the model.

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Velocity tuned generalized Sobel operators for multiresolution computation of optical flow

Velocity tuned generalized Sobel operators for multiresoluti...

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The 1994 1st IEEE International Conference on Image processing

作者： Gökstorp, M. Danielsson, P.-E. Image Processing Laboratory Computer Engineering Division Department of Electrical Engineering Linköping University LinköpingS-581 83 Sweden

Optical flow computation may be divided into four processing steps where the first is extraction of image features suitable for flow estimation. Using a generalization of the basic flow constraint it is possible to estimate flow vectors from a set of feature images obtained from the input image sequence. Generalized Sobel operators provide a suitable set of feature extraction operators. The set of five filters up to second order provides good approximations of ideal edge and line detectors. A review of spatial and frequency constraints on optical flow suggests a multiresolution approach to optical flow where the initial feature extractors consists of velocity tuned operators. We show that two-dimensional generalized Sobel operators may be extended to spatio-temporal velocity tuned filters for optical flow estimation. Experimental results compare well to existing methods. © 1994 IEEE.

关键词： Optical flows

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TRENCH DOPING CONFORMALITY BY PLASMA IMMERSION ION-IMPLANTATION (PIII)

IEEE ELECTRON DEVICE LETTERS

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IEEE ELECTRON DEVICE LETTERS 1994年第6期15卷 196-198页

作者： YU, C CHEUNG, NW Plasma Assisted Materials Processing Laboratory Department of Electrical Engineering and Computer Sciences University of California Berkeley CA USA Dept. of Electr. Eng. & Comput. Sci. California Univ. Berkeley CA USA

Plasma immersion ion implantation (PIII) is a technique which can be used to conformally dope sidewalls of Si trenches. Using junction staining techniques and subsequently calibrating the observed stained depth to measured dose, dopant distributions inside Si trenches with aspect ratios ranging from 1 to 12 are studied for various bias voltages from 5 to 20 kV. Unlike conventional collimated beam implantation, PIII was able to conformally dope all aspect ratios studied with no evidence of abrupt discontinuities in the dopant distribution along the trench surface as a result of beam shadowing by trench geometry. Furthermore, it is shown that the higher implant biases results in more directional trajectories. Thus, dopant distributions along irregular geometries can be controlled by PIII process conditions.

关键词： Doping Plasma immersion ion implantation Ion implantation Surface topography Plasma applications Plasma measurements Voltage Implants Plasma materials processing Geometry

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Correspondence of coplanar features through P2-invariant representations 2nd

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2nd Joint European–US Workshop on Applications of Invariance in computer Vision, 1993

作者： Meer, Peter Ramakrishna, Sudhir Lenz, Reiner Department of Electrical and Computer Engineering Rutgers University P.O. Box 909 PiscatawayNJ08855-0909 United States Image Processing Laboratory Department of Electrical Engineering Linköping University LinköpingS-58183 Sweden

ISBN: (纸本)9783540582403

An algorithm for establishing the correspondence between two projectively transformed sets of coplanar points (or lines) is proposed and its performance analyzed. Five-tuples of features are represented by projective/permutation (P2) invariants which are insensitive to the order of the features in the computation. Matched five-tuples yield feature correspondence hypotheses accumulated in a contingency table. The final correspondence is extracted from the table by a greedy algorithm. Positional uncertainties of up to five pixels and the presence of outliers are tolerated. © 1994, Springer Verlag. All rights reserved.

关键词： computers

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Computing depth from out-of-focus blur using a local frequency representation

Computing depth from out-of-focus blur using a local frequen...

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International Conference on Pattern Recognition

作者： M. Gokstorp Image Processing Laboratory Computer Engineering Division Department of Electrical Engineering Linkoping University Sweden

We present a method to compute depth from the amount of defocus in two images obtained from the same view-point but with different camera parameter settings. The change in defocus (blur) between the two images is proportional to the depth in the scene. We introduce a novel method to estimate the blur using a multiresolution local frequency representation of the input image pair. A confidence measure is used to discriminate between high error and low error blur estimates. Quantitative experimental results are shown for both real and synthetic images.

关键词： Layout Cameras Frequency estimation Robustness Lenses Focusing Optical imaging Geometry Image processing Laboratories

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Velocity tuned generalized Sobel operators for multiresolution computation of optical flow

Velocity tuned generalized Sobel operators for multiresoluti...

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IEEE International Conference on Image processing

作者： M. Gokstorp P.-E. Danielsson Image Processing Laboratory Computer Engineering Division Department of Electrical Engineering Linköping University Sweden

关键词： Optical computing Image motion analysis Optical filters Band pass filters Gabor filters Feature extraction Spatial resolution Frequency Equations Image edge detection

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