[Zhou, Jian;Li, Li-jun] Ctr S Univ Forestry & Technol, Machinery & Elect Engn Coll, Changsha 410004, Hunan, Peoples R China.^[Zhou, Wen-xiu] Lanjiang Sch, Changning 421500, Peoples R China.^[Zhou, Dong-cheng] Telecom Corp, Changning 421500, Peoples R China.^[Cheng, Ke] Guangxi Univ Technol, Lushan Coll, Liuzhou 545616, Peoples R China.