WILLIAM L. LUYBEN, PhD, is Professor of Chemical Engineering at Lehigh University. In addition to thirty-eight years of teaching, Dr. Luyben spent nine years as an engineer with Exxon and DuPont. Over the years, he has written eight books and more than 200 papers. He was the 2004 recipient of the Computing Practice Award from the CAST Division of the AIChE and was elected in 2005 to the Process Automation Hall of Fame.