1. School of Mechanical Engineering, Shijiazhuang Tiedao Univ., Shijiazhuang, Hebei; Key Laboratory of Opto-Technology and Intelligent Control, Ministry of Education, Lanzhou Jiaotong Univ., Lanzhou, Gansu, China
2. School of Mechanical Engineering, Shijiazhuang Tiedao Univ., Shijiazhuang, Hebei, China
3. Dept. of Foreign Language, Shijiazhuang Tiedao Univ., Shijiazhuang, Hebei, China