1. School of Mechanical Engineering, Xi’an Jiaotong University and State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an 710049, China
2. School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore
3. Institute of Microelectronics, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, #08-02 Innovis Tower, Singapore 138634, Singapore
4. Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States