1. Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System School of Mechanical Engineering Xi'an Jiaotong University Xi'an 710049 P. R. China
2. Institute of Design Science and Basic Components School of Mechanical Engineering Xi'an Jiaotong University Xi'an 710049 P. R. China
3. Key Laboratory of Biomedical Information of Ministry of Education School of Life Science and Technology Xi'an Jiaotong University Xi'an 710049 P. R. China