1. School of Transportation, Southeast University, 2 Sipailou St., Xuanwu Zone, Nanjing, Jiangsu Province 210096, China (Corresponding author), e-mail: chenxh@seu.edu.cn
2. Monash-SEU Joint School, Southeast University, No. 7 Building, No. 377 Linquan St., Dushuhu Science and Education Zone, Suzhou, Jiangsu Province 215123, China
3. China Railway Corporation, 10 Fuxing Rd., HaiDian District, Beijing 100844, China
4. China Academy of Railway Sciences, 2 DaLiuShu Rd., HaiDian District, Beijing 100081, China
5. School of Transportation, Southeast University, 2 Sipailou St., Xuanwu Zone, Nanjing, Jiangsu Province 210096, China