1. Department of Mechanical Engineering, Faculty of Engineering; University of Malaya; 50603 Kuala Lumpur Malaysia
2. Department of Petroleum and Chemical Engineering, Faculty of Engineering; Institute Technology Brunei; Tungku Gadong, P.O. Box 2909 Brunei Darussalam
3. School of Science and Engineering; Teesside University; Middlesbrough TS1 3BA UK