1. MOE Key Laboratory for Urban Transportation Complex Systems Theory and Technology, Beijing Jiaotong University, 100044 Beijing, China; and School of Engineering Science, University of Science and Technology of China, 230026 Hefei, China
2. School of Engineering Science, University of Science and Technology of China, 230026 Hefei, China
3. State Key Laboratory of Fire Science, University of Science and Technology of China, 230026 Hefei, China