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Finite-element mesh generation using self-organizing neural networks

computer-Aided Civil and Infrastructure engineering 1997年第4期12卷 233-250页

作者： Manevitz, Larry Yousef, Malik Givoli, Dan Dept. of Math. and Computer Science University of Haifa Haifa Israel Faculty of Aerospace Engineering Technion-Israel Inst. of Technology Haifa Israel

Neural networks are applied to the problem of mesh placement for the finite-element method. When the finite-element method is used to numerically solve a partial differential equation with boundary conditions over a domain, the domain must be divided into "elements." The precise placement of the nodes of the elements has a major affect on the accuracy of the numeric method. In this paper the self-organizing algorithm of Kohonen is adapted to solve the problem of automatically assigning (in a near-optimal way) coordinates from a two-dimensional domain to a given topologic grid (or mesh) of nodes in order to apply the finite-element method effectively when solving a partial differential equation with boundary conditions over that domain. One novelty of the method is the interweaving of versions of the Kohonen algorithm in different dimensions simultaneously in order to handle the boundary of the domain properly. Our method allows for the use of arbitrary types of two-dimensional elements (in particular, quadrilaterals or mixed shapes as opposed to just triangles) and for varying desired densities over the domain. (Thus more elements can be placed automatically near "areas of interest.") The methods and experiments developed here are for two-dimensional domains but seem naturally extendible to higher-dimensional problems. The method uses a mixture of both one- and two-dimensional versions of the Kohonen algorithm, with an improvement suggested by Tabakman and Exman, and further adapted to the particular problem here. Experimental results comparing this algorithm with a well-known two-dimensional grid-generating system (PLTMG) are presented. © 1997 Microcomputers in Civil engineering. Published by Blackwell Publishers.

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Performance analysis of minimum variance CDMA receivers

Performance analysis of minimum variance CDMA receivers

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International Conference on Digital Signal Processing (DSP)

作者： M.K. Teatsanis Zhengyuan Xu Dept. of Electr. & Comput. Eng. Stevens Inst. of Technol. Hoboken NJ USA Elcctrical & Computer Engineering Department Stevens Institute of Technology Hoboken NJ USA

Constrained optimization of the receiver's output variance has been proposed as a relatively simple method for designing blind multiuser detectors for DS-CDMA systems. A single constraint is sufficient to avoid signal cancellation in the AWGN case, while multiple constraints should be used in a multipath environment. A max/min approach for optimizing the constraint is proposed, resulting in blind solutions with improved performance. It is shown that the performance of the proposed method approaches that of the MMSE receiver at high SNR, while the constraint parameters converge to the multipath channel parameters. The proposed method does not require knowledge of the interfering users' codes and timing. Simulation results support those performance claims.

关键词： Performance analysis Multiaccess communication Constraint optimization Delay Design optimization Design methodology Detectors Multipath channels Timing Training data

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Associative memory design via perceptron learning

Associative memory design via perceptron learning

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International Conference on Neural Networks

作者： Derong Liu Zanjun Lu Dept. of Electr. & Comput. Eng. Stevens Inst. of Technol. Hoboken NJ USA Department of Electrical and Computer Engineering Stevens Institute of Technology Hoboken NJ USA

ISBN: (纸本)0780341228

In the present paper, a new synthesis approach is developed for associative memories based on the perceptron learning algorithm. The design (synthesis) problem of feedback neural networks for associative memories is formulated as a set of linear inequalities such that the use of perceptron learning is evident. The perceptron learning in the synthesis algorithms is guaranteed to converge. To demonstrate the applicability of the present results, a specific example is considered.

关键词： Associative memory Network synthesis Neural networks Neurofeedback Design methodology Information retrieval Prototypes Equations Design optimization Linear programming

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Multiobjective search based algorithms for circuit partitioning problem for acceleration of logic simulation

Multiobjective search based algorithms for circuit partition...

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International Conference on VLSI Design

作者： S. Harikumer S. Kumar Dept. of Comput. Sci. & Eng. Indian Inst. of Technol. New Delhi India Department of Computer Science and Engineering Indian Institute of Technology New Delhi India

Speeding up logic simulation is important to reduce design time of complex systems. Hardware emulation through reconfigurable systems (RS) built using FPGA's offer an cheap and efficient method to achieve the required speed-up. Emulation through RS poses some unique problems because of the limited circuit and I/O resources. A preparatory step for emulation using RS is to partition the circuit into as few parts as possible satisfying the resource constraints. This paper presents multi-objective search based optimal and approximate algorithms for circuit partitioning for this purpose.

关键词： Partitioning algorithms Acceleration Logic circuits Circuit simulation Field programmable gate arrays Hardware Logic design Computational modeling Emulation Circuit testing

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Optimized aluminum back surface field techniques for silicon solar cells

Optimized aluminum back surface field techniques for silicon...

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Conference Record of the Twenty Sixth IEEE Photovoltaic Specialists Conference - 1997

作者： S. Narasinha A. Rohatgi Dept. of Electr. & Comput. Eng. Georgia Inst. of Technol. Atlanta GA USA Department of Electrical and Computer Engineering Georgia Institute of Technology University Center of Excellence for Photovoltaics Research and Education Atlanta GA USA

Screen-printed Al and rapid thermal alloying have been combined in order to achieve an Al back surface field (Al-BSF) which lowers the effective back surface recombination velocity to 200 cm/s on 2.3 /spl Omega/cm Si. This Al-BSF process has been integrated into a high-efficiency, laboratory fabrication sequence as well as a high-throughput, industrial-type process in order to achieve solar cell efficiencies in excess of 19.0% and 17.0%, respectively, on 2.3 /spl Omega/cm FZ Si. For both process sequences, the efficiency values are 1-2 absolute percentage points higher than cells made with unoptimized Al-BSFs. The critical process requirements for optimal Al-BSF formation are: (1) the use of a fast ramp rate to reach the alloying temperature; and (2) thick film Al deposition prior to alloying.

关键词： Aluminum Silicon Alloying Rapid thermal processing Laboratories Fabrication Textile industry Photovoltaic cells Temperature Thick films

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SILO: INTEGRATING LOGIC IN OBJECTS FOR KNOWLEDGE REPRESENTATION AND REASONING

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International Journal on Artificial Intelligence Tools 1996年第4期5卷 403-446页

作者： IOANNIS HATZILYGEROUDIS University of Patras School of Engineering Dept of Computer Engineering & Informatics 26500 Patras Greece Computer Technology Institute (CTI) P.O. Box 1122 26110 Patras Greece

There have been a large number of systems that integrate logic and objects (frames or classes) for knowledge representation and reasoning. Most of those systems give pre-eminence to logic and their objects lack the structure of frames. These choices imply a number of disadvantages, as the inability to represent exceptions and perform default reasoning, and the reduction in the naturalness of representation. In this paper, aspects of knowledge representation and reasoning in SILO, a system integrating logic in objects, are presented. SILO gives pre-eminence to objects. A SILO object comprises elements from both frames and classes. A kind of many-sorted logic is used to express object internal knowledge. Message passing, alongside inheritance, plays a significant role in the reasoning process. Control knowledge, concerning both deduction and inheritance. is separately and explicitly represented via definitions of certain functions, called meta-functions.

关键词： logic frames classes knowledge representation hybrid system meta-level system

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On transformations into linear database logic programs 2nd

On transformations into linear database logic programs

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2nd International Conference on Perspectives of Systems informatics, 1996

作者： Afrati, Foto Gergatsoulis, Manolis Katzouraki, Maria Dept. of Electrical and Computer Engineering National Technical University of Athens Athens157 73 Greece Inst. of Informatics and Telecom. N.C.S.R. ‘Demokritos’ 153 10 A. Paraskevi Attikis Greece

ISBN: (纸本)3540620648

We consider the problem of transformations of logic programs without function symbols (database logic programs) into a special subclass, namely linear logic programs. Linear logic programs are defined to be the programs whose rules have at most one intentional atom in their bodies. a) We investigate linearizability of several syntactically defined subclasses of programs and present both positive and negative results (i.e. demonstrate programs that cannot be transformed into a linear program by any transformation technique), and b) We develop an algorithm which transforms any program in a specific subclass namely the piecewise logic programs into a linear logic program. © Springer-Verlag Berlin Heidelberg 1996.

关键词： computer circuits

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Flowchart tutoring system with error diagnostic capabilities using program slicing

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SYSTEMS AND computerS IN JAPAN 1996年第13期27卷 86-98页

作者： Okada, S Fujiwara, Y Matsunishi, T Ohkama, H Department of Computer Sciences Faculty of Engineering Kitami Institute of Technology Kitami 090 Japan Kitami Inst. Technol. Electron. Eng. Dept. of Information Engineering Kitami Institute Department of Computer Sciences Kitami Institute Inst. Electronics Info. Commun. E. Info. Processing Society of Japan Department of Computer Sciences Kitami Institute of Technology Hokkaido University Japan NTT Kitami Institute of Technology IEEE ACM Japan. Soc. for Artif. Intelligence

For creation of a good program, excellent structured description is required for the algorithm. In this paper, a flowchart tutoring system is proposed. This system supports the flowchart description by each student and diagnoses its validity in the programming exercise process. First, a cooperative distributed method to support the flowchart description using the hierarchical structure of the structured programming is shown. A hierarchical diagnosis method consisting of syntax, logical structure and semantic validity diagnosis is explained. Algorithms using program slicing are proposed for the semantic validity diagnosis.

关键词： flowchart structured programming blackboard model program slicing

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Comparison of two architectures for implementation of the discrete cosine transform

Comparison of two architectures for implementation of the di...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： I. Sundsbo G. Lokken Hansen E.J. Aas Dept. of Electr. & Comput. Eng. Norwegian Inst. of Technol. Trondheim Norway Geometri USA Faculty of Electrical Engineering and Computer Science Norwegian Institute of Technology USA

A new DCT architecture developed by Mou and Jutand (1991) is compared to an architecture based on distributed arithmetic with ROMs realized as random logic. Both architectures have been implemented in 0.8 /spl mu/m CMOS technology and optimized with different constraints on area and timing. The results reveal that for HDTV applications the design with distributed arithmetic is superior, with lower power consumption and less than half the chip area.

关键词： Discrete cosine transforms Arithmetic computer architecture Encoding Matrix decomposition CMOS technology HDTV Energy consumption Image coding computer science

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Neural networks for ultrasonic grain size discrimination

Neural networks for ultrasonic grain size discrimination

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IEEE Symposium (IUS) Ultrasonics

作者： M. Unluturk J. Saniie Dept. of Electr. & Comput. Eng. Illinois Inst. of Technol. Chicago IL USA Electrical and Computer Engineering Department Illinois Institute of Technology Chicago IL USA

In this study, we have developed the grain power spectrum neural network (GPSNN) to classify the ultrasonic backscattered grain signals for material characterization. The GPSNN has 32 input nodes, 13 hidden neurons determined adaptively, and one summing output node. A set of 4490 training sequences is utilized to train the neural network. A new set of 12572 testing sequences is used to test GPSNN performance. The samples tested for grain size discrimination are steel with grain sizes of 14 and 50 microns. GPSNN achieves an average recognition performance of over 98%. This high level of recognition suggests that the GPSNN is a promising method for ultrasonic nondestructive testing.

关键词： Neural networks Grain size Rayleigh scattering Acoustic scattering Testing Signal design Neurons Microstructure Frequency estimation Ultrasonic variables measurement

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