Authors
Tian Shu-yao
School of Electrical Engineering, Yanshan University, Qinhuangdao, P.R. China
School of Electromechanical, Hebei Normal University Of Science & Technology, Qinhuangdao, P.R. China
Hu Chun-hai
School of Electrical Engineering, Yanshan University, Qinhuangdao, P.R. China