Robert M. Peart is Graduate Research Professor Emeritus, Department of Agricultural and Biological Engineering, University of Florida, Gainesville. The editor or coeditor of several books, including Agricultural Systems Modeling and Simulation (Marcel Dekker, Inc.), he is the author of more than 60 scientific papers and holds three patents. A Fellow and former director of the American Society of Agricultural Engineers and a member of the American Association for Artificial Intelligence, Dr. Peart received the Ph.D. degree (1960) in agricultural engineering from Purdue University, West Lafayette, Indiana.W. David Shoup is Professor of Agricultural and Biosystems Engineering, Electrical Engineering, and Public Policy, Southern Illinois University, Carbondale. The author of over 450 publications related to food and agricultural systems management, Dr. Shoup has consulted with over 200 companies and corporations in the area of technical and systems management. He is a life member of the American Society of Agricultural Engineers, the International Society of Pharmaceutical Engineers, and the National Farmer's Union. During his career in technical management, Professor Shoup held various management positions for Tenneco Inc. and professorial positions with the University of Florida, University of Arizona, University of Tennessee, and Southern Illinois University. Dr. Shoup received the Ph.D. degree (1980) in agricultural systems from Purdue University, West Lafayette, Indiana.