1. Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, Xi’an Jiaotong University, Xi'an, P.R. China
2. Luoyang LYC Bearing Limited Company, Luoyang, P.R. China
3. State Key Laboratory of Aviation Precision Bearings, Luoyang, P.R. China
4. School of Mechanical Engineering, Anhui Polytechnic University, Wuhu, P.R. China