Date of Award

1989

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Electrical and Computer Engineering

First Advisor

Subhash C. Kak

Abstract

Neural networks offer distributed processing power, error correcting capability and structural simplicity of the basic computing element. Neural networks have been found to be attractive for applications such as associative memory, robotics, image processing, speech understanding and optimization. Neural networks are self-adaptive systems that try to configure themselves to store new information. This dissertation investigates two approaches to improve performance: better learning and supervisory control. A new learning algorithm called the Correlation Continuous Unlearning (CCU) algorithm is presented. It is based on the idea of removing undesirable information that is encountered during the learning period. The control methods proposed in the dissertation improve the convergence by affecting the order of updates using a controller. Most previous studies have focused on monolithic structures. But it is known that the human brain has a "bicameral" nature at the gross level and it also has several specialized structures. In this dissertation, we investigate the computing characteristics of neural networks that are not monolithic being enhanced by a controller that can run algorithms that take advantage of the known global characteristics of the stored information. Such networks have been called bicameral neural networks. Stinson and Kak considered elementary bicameral models that used asynchronous control. New control methods, the method of iteration and bicameral classifier, are now proposed. The method of iteration uses the Hamming distance between the probe and the answer to control the convergence to a correct answer, whereas the bicameral classifier takes advantage of global characteristics using a clustering algorithm. The bicameral classifier is applied to two different models of equiprobable patterns as well as the more realistic situation where patterns can have different probabilities. The CCU algorithm has also been applied to a bidirectional associative memory with greatly improved performance. For multilayered networks, indexing of patterns to enhance system performance has been studied.

Pages

155

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