William L. Luyben, PhD, is a Professor of Chemical Engineering at Lehigh University. In addition to teaching for forty years, Dr. Luyben spent nine years as an engineer with Exxon and DuPont. He has written nine books, including Distillation Design and Control Using Aspen Simulation (Wiley), and more than 200 papers. He was awarded the AIChE CAST Division "Computing Practice Award" in 2003 and elected to the Process Automation Hall of Fame in 2005.