1. Rail Transit Institute, Henan College of Transportation, No.259 Tonghui Road, Baisha Vocational Education Park, Zhengdong New District, Zhengzhou 450061, China
2. School of Electronic and Information, Zhongyuan University of Technology, No.41 Zhongyuan Road, Zhengzhou 450007, China
3. Graduate School of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan