1. School of Electrical and Electronics EngineeringNanyang Technological Universit 50 Nanyang Ave Singapore 639798 Singapore
2. Department of Mechanical EngineeringNational Chung Cheng University Minhsiung Chiayi 62102 Taiwan, ROC
3. Key Lab of Advanced Transducers and Intelligent Control System of Ministry of EducationTaiyuan University of Technology Taiyuan 030024 P. R. China
4. School of Chemical and Biomedical EngineeringNanyang Technological University 62 Nanyang Drive Singapore