[Li, Youfu; Xie, Bochen] City Univ Hong Kong, Dept Mech Engn, Hong Kong, Peoples R China.
[Deng, Yongjian] Beijing Univ Technol, Coll Comp Sci, Beijing, Peoples R China.
[Shao, Zhanpeng] Hunan Normal Univ, Coll Informat Sci & Engn, Changsha, Peoples R China.
[Liu, Hai] Cent China Normal Univ, Natl Engn Res Ctr E Learning, Wuhan, Peoples R China.
[Xu, Qingsong] Univ Macau, Dept Electromech Engn, Macau, Peoples R China.