1. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, College of Mechanical and Vehicle Engineering, Hunan University, Changsha City 410082, P. R. China
2. National Defense Key Laboratory of Antennas and Microwave Technology, Nanjing City 210039, P. R. China
3. School of Mechanical and Electrical Engineering, Hunan City University, Yiyang City 413002, P. R. China
4. Key Laboratory of Electronic Equipment, Structure Design of Ministry of Education, School of Electro-Mechanical Engineering, Xidian University, Xi’an City 710071, P. R. China