1. State Key Laboratory of Advanced Rail Autonomous Operation, Beijing Jiaotong University, Beijing, People's Republic of China
2. State Key Laboratory of Integrated Services Networks, Xidian University, Xi'an, People's Republic of China
3. Department of Mathematics, Beijing Jiaotong University, Beijing, People's Republic of China
4. School of Systems Science, Beijing Jiaotong University, Beijing, People's Republic of China