1. Department of Mathematics and Physics, Beijing Institute of Petrochemical Technology, Beijing 102617, China
2. State Key Laboratory for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871, China
3. School of Electrical and Electronics Engineering, East China Jiaotong University, Nanchang 330013, China
4. School of Electric and Information Engineering, Guangxi University of Science and Technology, Liuzhou 545006, China