1. Traction Power State Key Laboratory, Southwest Jiaotong Univ., Chengdu, Sichuan; Zhengzhou Railway Vocational & Technical College, Zhengzhou, Henan.
2. Professor, Traction Power State Key Laboratory, Southwest Jiaotong Univ., Chengdu, Sichuan
3. Professor, Zhengzhou Railway Vocational & Technical College, Zhengzhou, Henan.