1. School of Rail Transportation, Soochow University, Suzhou 215131, Jiangsu, P. R. China
2. Soochow College, Soochow University, Suzhou 215006, Jiangsu, P. R. China
3. Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China
4. School of Automotive Engineering, Changzhou Institute of Technology, Changzhou 213032, Jiangsu, P. R. China