[Zhang, Xiao-Fei] Cent China Normal Univ, Sch Math & Stat, Wuhan 430079, Peoples R China.
[Dai, Dao-Qing; Le Ou-Yang] Sun Yat Sen Univ, Intelligent Data Ctr, Guangzhou 510275, Guangdong, Peoples R China.
[Dai, Dao-Qing; Le Ou-Yang] Sun Yat Sen Univ, Dept Math, Guangzhou 510275, Guangdong, Peoples R China.
[Hu, Xiaohua] Cent China Normal Univ, Sch Comp, Wuhan 430079, Peoples R China.
[Hu, Xiaohua] Drexel Univ, Coll Informat Sci & Technol, Philadelphia, PA 19104 USA.