1. School of Engineering & Key Laboratory of Ocean Engineering of Shandong Province, Ocean University of China, Qingdao 266100, China
2. Department of Electrical, Electronic and Computer Engineering, University of Pretoria, Pretoria 0002, South Africa
3. School of Mechanical, Materials, Mechatronic and Biomedical Engineering, University of Wollongong, Wollongong, NSW 2522, Australia