HYBRID NEURAL NETWORK AND EXPERT SYSTEMS

HYBRID NEURAL NETWORK AND EXPERT SYSTEMS

HYBRID NEURAL NETWORK AND EXPERT SYSTEMS by Larry R. Medsker Department of Computer Science and Information Systems The American University... " Springer Science+Business Media, LLC

Library of Congress Cataloging-in-Publication Data Medsker, Larry. Hybrid neural network and expert systems / Larry R. Medsker. p. cm. Includes bibiiographicai references and index. ISBN 978-1-4613-6175-6 ISBN 978-1-4615-2726-8 (ebook) DOI 10.1007/978-1-4615-2726-8 l. Neural networks (Computer science) 2. Expert systems (Computer science) I. Title. QA76.87.M43 1994 006.3--dc20 93-38572 CIP Copyright C 1994 by Springer Science+Business Media New York Originally published by Kluwer Academic Publishers in 1994 Softcover reprint ofthe hardcover Ist edition 1994 AlI rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, mechanicai, photo-copying, recording, or otherwise, without the prior written permission of the publisher, Springer Science+Business Media, LLC. Printed on acid-free paper.

Dedicated to Masud and Dalila Harold David Alan, Fran, Mike, Silvana, Xiaojing Sean, Monty, Geoff, Mark, Kirk, Kevin, Nabin, Mary and Bob

Table of Contents PREFACE................................. xi PART I Fundamentals of Hybrid Systems.... 1 CHAPTER 1 Overview of Neural and Symbolic Systems. 1.1 Expert System Strengths and Limitations.. 1.2 Neural Computing.............. 1.3 Using Neural Networks in Symbolic Processing Applications.................... 1.4 Neural Network and Expert System Comparisons. 3 3 6 17 19 CHAPTER 2 Research in Hybrid Neural and Symbolic Systems 2.1 Hybrid Reasoning....... 2.2 Hybrid System Research Areas 2.3 AAAI-92 Workshop.... 2.4 Development Tools...... 2.5 Status and Direction of Research and Development 21 21 22 28 30 33

CHAP1ER 3 Models for Integrating Systems. 35 3.1 IRIS Model 0 0 0 0 0 0 35 3.2 Models for Integration. 37 3.3 Summary....... 46 PART II Case Studies of Hybrid Neural Network and Expert Systems.. 47 CHAP1ER 4 LAM Hybrid System for Window Glazing Design 49 4.1 Laminated Glass and Window Glazing Design... 50 4.2 Architecture, Design, and Development of LAMtm 57 4.3 Operational use oflamtm. 64 4.4 Conclusions.. 0 0 74 CHAPTER 5 Hybrid Systems Approach to Nuclear Plant Monitoring 77 5.1 Introduction... 77 5.2 Formulation of the Problem. 80 5.3 Identification of Neural Network Strategies 85 5.4 Neural Network Development. 90 5.5 Expert System Development 96 5.6 Hybrid System Development 101 5.7 Nuclear Monitoring System Evaluation. 103 5.8 Conclusions 0 0 107 CHAP1ER 6 Chemical Tank Control System.......... 109 6.1 Overview of the Chemical Tank Control Problem 109 6.2 The PDP Hybrid Neural NetworklExpert System. 110 6.3 Drawbacks in the COnstruction of the Hybrid System 113 6.4 Improving the Chemical Tank Control System with Conncert. 0 116 6.5 Future Enhancements 119

CHAPTER 7 Image Interpretation Via Fusion of Heterogeneous Sources Using a Hybrid Expert-Neural Network System 121 7.1 Introduction.... 121 7.2 InFuse Architecture 124 7.3 Data Representation and Feature Characterization. 126 7.4 Terrain Classification and Refinement. 130 7.5 Results and Discussion........ 134 CHAPTER 8 Hybrid System for Multiple Target Recognition 139 8.1 Introduction... 139 8.2 Hybrid System Description 144 8.3 Hybrid System Implementation 152 8.4 Trade Studies... 169 8.5 Summary, Conclusions, & Recommendations 178 PART III Analysis and Guidelines..................... 181 CHAPTER 9 Guidelines for Developing Hybrid Systems...... 183 9.1 Characteristics of Expert System and Neural Network. 183 9.2 Hybrid System Development Issues and Methodology 186 9.3 Development Process.. 191 9.4 Analysis of Case Studies 200 9.5 Summary........ 201 CHAPTER 10 Tools and Development Systems 203 10.1 Hybrid System Software...... 203 10.2 Neural Network Hardware..... 205 10.3 The NueX Development Environment. 207 10.4 Other Development Environments, 210 10.5 Summary............. 212

CHAPlER 11 Summary and the Future of Hybrid Neural Network and Expert Systems. 215 11.1 Introduction.......... 215 11.2 Other Intelligent Technologies. 217 11.3 Neurocontrol.......... 219 11.4 Future Research and Development in Hybrid Systems. 220 REFERENCES... 223 INDEX... 239

Preface Three years ago, when I started presenting tutorials on the integration of neural networks and expert systems, I could uncover only enough work in this area to fill one page of references. Today we see mpidly growing interest and an order of magnitude more projects on hybrid systems that combine neural networks and expert systems. Working systems have been developed for demonstrating feasibility and some are actually in use in practical situations. Several developments have stimulated these activities. Attention has grown in the research community, including a recognition among some AI researchers that combined approaches will be necessary if the remaining tough problems in AI are to be solved. The rapid developments in R&D for neural networks have produced many applications and development tools. Both the expert system and the neural network technologies are at stages in which useful hybrid systems are conveniently possible. The current opportunity is to develop more efficient and effective design and development techniques to enable widespread production of useful and practical systems. Work is also needed to clarify the range of appropriate problems. Progress in hybrid systems will advance more rapidly as we share ideas and experiences, allowing practical models and guidelines to emerge. This book is a step toward summarizing the state of hybrid systems and disseminating information about working systems that illustrate the issues and opportunities in this field. While other intelligent technologies should be considered eventually, the current focus is on the two that have a peculiarly complementary nature: the logical, reasoning aspect of expert systems and the visual, pattern-oriented nature of neural networks. Together they represent the mnge of human intelligence that is difficult or impossible to simulate with either technology alone.

The first part of the book summarizes the concepts and principles of neural networks and expert systems that are relevant to the integration of the two. The status of research in hybrid systems is summarized, and initial models for integration are presented. Next, five case studies are presented in detail so that the nature of the problems and the design and implementation processes are clear. The applications cover product design using the analysis of technical data, control systems using the analysis of detector and sensor data, and the monitor and control of chemical processes. An important thread is the need to process data, often in large quantities, for efficient use in decision making. The final part of the book covers guidelines and methodologies for hybrid system development and surveys the current choices for development tools and environments. While systems are currently being developed and used, the next few years should see dramatic improvements in these areas, and the fmal chapter presents ideas about what we can expect. This book contains the results of my literature survey and analysis of hybrid systems research and applications development. Some of the material also derives from my experience developing hybrid systems, and for that I gratefully acknowledge the contributions of my students and colleagues. In particular, the collaborations with Masud Cader, Dalila Benachenhou, and Harold Szu were essential. Students in my NSF-sponsored Research Experiences for Undergraduates (REU) programs and American University graduate students Fran Labate, Silvana Rubino, and Michael Bramante also made important contributions. Thanks go to Ron Sun at the University of Alabama for information on the AAAI-92 Workshop. Special thanks go to the case study contributors for their pioneering work in hybrid systems applications and for their work in sharing the results in this book. I am particulary grateful to Ray Foss at DuPont; Alper Caglayan, Jim Mazzu, and Paul Gonsalves at Charles River Analytics, Inc.; Laveen Kanal and Srinivasan Raghavan at LNK Corp.; and Jim Hendler and Anne Wilson at the University of Maryland. Finally, I appreciate the assistance of Alper Caglayan at Charles River Analytics, Inc. and Steve Ward and Marge Sherald at Ward Systems, Inc. in the use of NueX and NeuroShell, respectively. I also appreciate the use of some figures and text from my chapters in Hybrid Architectures for Intelligent Systems (CRC Press), Expert Systems and Applied Artificial Intelligence (Macmillan Publishing Co.), and Design and Development of Expert Systems and Neural Networks (Macmillan Publishing Co.).