1. Professor, Dept. of Electrical Engineering, Henan Univ. of Technology, Zhengzhou 450001, PR China (corresponding author).
2. Master’s Student, Dept. of Electrical Engineering, Henan Univ. of Technology, Zhengzhou 450001, PR China.
3. Lecturer, Dept. of International Education, Zhengzhou Railway Vocational & Technical College, Zhengzhou 451460, PR China.
4. Associate Professor, Dept. of International Education, Zhengzhou Railway Vocational & Technical College, Zhengzhou 451460, PR China.