1. College of Automation Engineering , Nanjing University of Aeronautics and Astronautics , Nanjing , 211106 , China
2. Nondestructive Detection and Monitoring Technology for High Speed Transportation Facilities , Key Laboratory of Ministry of Industry and Information Technology , Nanjing 211106 , China
3. Department of Electrical and Electronic Engineering , The University of Manchester , Manchester , M13 9PL , UK
4. School of Mechanical Engineering , Hebei University of Technology , Tianjin 300130 , China