1. Senior Engineer, Hellenic Petrol, 5 Chimaras St., 15125 Athens, Greece; formerly, Dept. of Mechanical Science and Engineering, Univ. of Illinois at Urbana-Champaign, 1206 W. Green St., Urbana, IL 61801.
2. Associate Professor, Dept. of Mechanical Science and Engineering, Univ. of Illinois at Urbana-Champaign, 1206 W. Green St., Urbana, IL 61801; and Professor, Dept. of Mechanical Engineering, Khalifa Univ. of Science, Technology and Research, P.O. Box 127788, Abu Dhabi, United Arab Emirates (corresponding author).