Frontiers of Engineering is the fifth book highlighting the presentations of the National Academy of Engineering's (NAE) annual symposium series, Frontiers of Engineering. The 1999 NAE Symposium on Frontiers of Engineering was held October 14-16, at the Academies' Beckman Center in Irvine, California. The 101 emerging engineering leaders (ages 30-45) from industry, academia, and federal laboratories who attended the meeting heard presentations and discussed cutting-edge research and technical work in four engineering fields. Symposium speakers were asked to prepare extended summaries of their presentations, and it is those papers that are contained here. The intent of this book, and of the four that precede it in the series, is to describe the content and underpinning philosophy of this unique meeting and to highlight some of the exciting developments in engineering today.