1. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body , Hunan University , Changsha , Hunan 410082 , P.R. China
2. Department of Mechanical Engineering , Hong Kong Polytechnic University , Hong Kong SAR , P.R. China
3. Department of Electronic and Electrical Engineering, University College London , London WC1E 7JE , UK
4. School of Physics Science and Engineering , Tongji University , Shanghai 200092 , P.R. China