[Zhao, Junmin] Cent China Normal Univ, Natl Engn Res Ctr E Learning, Wuhan, Peoples R China.^[Hu, Xiaohua;He, Tingting;Li, Peng;Zhang, Ming;XianjunShen] Cent China Normal Univ, Sch Comp, Wuhan, Peoples R China.^[Hu, Xiaohua] Drexel Univ, Coll Informat Sci & Engn, Philadelphia, PA USA.^[Zhao, Junmin] Henan Univ Urban Construct, Inst Comp Sci & Engn, Pingdingshan, Peoples R China.