1. Research Fellow, Dept. of Mechanical Engineering, National Univ. of Singapore, 5 Engineering Dr. 2, Singapore 117579 (corresponding author).
2. Associate Professor, Dept. of Mechanical Engineering, National Univ. of Singapore, 9 Engineering Dr. 1, Singapore 117576.
3. Ph.D. Student, Dept. of Mechanical Engineering, National Univ. of Singapore, 3 Engineering Dr. 2, Singapore 117578.