[Huang, Jimmy Xiangji] Cent China Normal Univ, Informat Retrieval & Knowledge Management Res Lab, Wuhan, Hubei, Peoples R China.^[Jian, Fanghong] Cent China Normal Univ, Natl Engn Res Ctr E Learning, Wuhan, Hubei, Peoples R China.^[He, Tingting;Hu, Po] Cent China Normal Univ, Sch Comp Sci, Wuhan, Hubei, Peoples R China.^[Zhao, Jiashu] York Univ, Sch Informat Technol, Toronto, ON, Canada.