[1] Bohai Univ, Dept Math, Jinzhou 121013, Peoples R China
[2] Liaoning Inst Sci & Engn, Dept Informat Engn, Jinzhou, Peoples R China
[3] Texas A&M Univ Kingsville, Dept Math, Kingsville, TX USA
[4] Florida Inst Technol, Dept Appl Math, Melbourne, FL USA