Affiliation: | 1. School of Mathematics Science , Liaocheng University , Liaocheng 252000 , P.R. China;2. School of Automation , Southeast University , Jiangsu 210096 , China;3. School of Mathematics and Physics , Bohai University , Jinzhou 121003 , China;4. Center for Nonlinear and Complex Systems, School of Electronic Engineering , University of Electronic Science and Technology of China , Chengdu 611731 , P.R. China |