1. Center for Precision Engineering, Harbin Institute of Technology; Harbin 150001 China
2. Department of Mechanical Science and Engineering, Nagoya University; Nagoya 464-8603 Japan
3. Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Science; Changchun 130033 China
4. Center for Memory and Recording Research, University of California San Diego; La Jolla 92093 United States
5. School of Mechatronics Engineering, Harbin Institute of Technology; Harbin 150001 China
6. School of Mechanical Engineering, Shanghai Jiao Tong University; Shanghai 200240 China