1. School of New Energy, Long Dong University, Qingyang, Gansu, China
2. School of Automation and Electrical Engineering, Tianjin University of Technology and Education, Tianjin, China
3. School of Vocational Education, Tianjin University of Technology and Education, Tianjin, China
4. School of Mechanical Engineering, Shandong Huayu University of Technology, Dezhou, Shandong, China