1. Graduate Student, Dept. of Mechanical Engineering, National Univ. of Singapore, Kent Ridge, Singapore 119260.
2. Professor, Engineering Science Programme and Dept. of Civil Engineering, National Univ. of Singapore, Kent Ridge, Singapore 119260 (corresponding author). E-mail: cvewcm@nus.edu.sg
3. Assistant Professor, Dept. of Mechanical Engineering, National Univ. of Singapore, Kent Ridge, Singapore 119260.