1. Associate Professor, School of Civil and Environmental Engineering, Nanyang Technological Univ., Nanyang Ave., Singapore 639798, Republic of Singapore.
2. Graduate Student, School of Civil and Environmental Engineering, Nanyang Technological Univ., Nanyang Ave., Singapore 639798, Republic of Singapore.
3. Graduate Student, Institute for Hydromechanics, Univ. of Karlsruhe, Germany.