1. Assistant Professor, Dept. of Management Science and Engineering, College of Economics and Management, Nanjing Univ. of Aeronautics and Astronautics, Nanjing 210000, China; formerly, Research Fellow, Dept. of Building, School of Design and Environment, National Univ. of Singapore, Singapore 119260 (corresponding author).
2. Assistant Professor, Dept. of Building, School of Design and Environment, National Univ. of Singapore, Singapore 119260.