William Shepherd is Professor of Electrical Engineering and Computer Science at Ohio University, Athens, Ohio. The author of four books and 150 scientific papers and patents, he is a Life Fellow of the Institute of Electrical and Electronics Engineers and a Fellow of The Institution of Electrical Engineers. His current research interests include energy conversion, power electronics, and renewable energy. Dr. Shepherd received the B.Sc. degree (1955) from Imperial College London, University of London, United Kingdom, the M.A.

Sc. degree (1958) from the University of Toronto, Ontario, Canada, and the Ph.D. (1966) and D.Sc. (1975) degrees from the University of London, United Kingdom. Li Zhang is a Lecturer in Electronic and Electrical Engineering at the University of Leeds, United Kingdom. The author or coauthor of many refereed journal papers, Dr.

Zhang is actively researching such areas as power electronic devices and converters and their applications in power systems and renewable energy. A member of the Institute of Electrical and Electronics Engineers and supervisor to numerous Ph.D. students. Dr. Zhang received the Ph.D. degree (1984) in control engineering from the University of Bradford, United Kingdom.