1. State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300130, P. R. China
2. School of Information Engineering, Tianjin University of Commerce, Tianjin 300134, P. R. China
3. National Institute on Drug Dependence and Beijing Key Laboratory of Drug Dependence, Peking University, Beijing 100191, P. R. China
4. School of Electronic and Information Engineering, Hebei University, Baoding 071002, P. R. China