1. Research Assistant, Dept. of Mechanical Engineering, International Islamic Univ. Malaysia, P.O. Box 10, 50728 Kuala Lumpur, Malaysia.
2. Professor, Dept. of Aeronautical Engineering, Univ. of Tripoli, P.O. Box 3601381, Tripoli, Libya.
3. Professor, Dept. of Mechanical Engineering, International Islamic Univ. Malaysia, P.O. Box 10, 50728 Kuala Lumpur, Malaysia (corresponding author).