[Zhang, Shangli] Beijing Jiaotong Univ, Sch Sci, Beijing 100044, Peoples R China.
[Zhang, Shangli] Beihang Univ, State Key Lab Virtual Real Technol & Syst, Beijing 100191, Peoples R China.
[Fang, Zhide] LSU Hlth Sci Ctr, Sch Publ Hlth, Biostat Sect, New Orleans, LA 70112 USA.
[Qin, Hong] Cent China Normal Univ, Fac Math & Stat, Wuhan 430079, Peoples R China.
[Han, Litao] Renming Univ, Sch Informat, Beijing 100872, Peoples R China.