[Xie, Wanli] Nanjing Normal Univ, Inst EduInfo Sci & Engn, Nanjing 210097, Peoples R China.
[Wu, Wen-Ze] Cent China Normal Univ, Sch Econ & Business Adm, Wuhan 430079, Peoples R China.
[Liu, Chong] Inner Mongolia Agr Univ, Sch Sci, Hohhot 010018, Peoples R China.
[Zhang, Tao] Guangxi Univ Sci & Technol, Sch Sci, Liuzhou 545006, Peoples R China.
[Dong, Zijie] Hubei Univ, Fac Math & Stat, Wuhan 430062, Peoples R China.