1. Zhuzhou CRRC Times Electric Co. , Ltd., Times Road, Shifeng District, Zhuzhou, Hunan, 412001 , China
2. Department of Statistics, University of Warwick , Coventry, CV4 7AL , United Kingdom
3. State Key Lab of Rail Traffic Control & Safety, Beijing Jiaotong University , Haidian District, Beijing, 100044 , China