1. Department of Automation and Electronic Engineering, Qingdao University of Science and Technology, Qingdao 266061, P. R. China
2. School of Mathematics and Physics, Qingdao University of Science and Technology, Qingdao 266061, P. R. China
3. Public Security Department, Shandong Police College, Jinan, 250014, P. R. China
4. College of Transportation, Shandong University of Science and Technology, Qingdao, 266590, P. R. China