[Liu, Anfeng; Mo, Wen] Cent South Univ, Sch Comp Sci & Engn, Changsha 410083, Peoples R China.
[Liu, Wei] Hunan Univ Chinese Med, Sch Informat, Changsha 410208, Peoples R China.
[Huang, Guosheng] Hunan First Normal Univ, Sch Informat Sci & Engn, Changsha 410205, Peoples R China.
[Xiong, Neal N.] Sul Ross State Univ, Dept Comp Sci & Math, Alpine, TX 79830 USA.
[Zhang, Shaobo] Hunan Univ Sci & Technol, Sch Comp Sci & Engn, Xiangtan 411201, Peoples R China.