1. School of Electronic Engineering, Guangxi University of Science and Technology, Liuzhou, Guangxi 545616, P.R. China
2. School of Automation, Guangxi University of Science and Technology, Liuzhou, Guangxi 545616, P.R. China
3. Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P.R. China