[1] Northwestern Polytech Univ, Dept Appl Math, Xian 710072, Peoples R China
[2] BV Raju Inst Technol, Dept Math, Medak 502313, Telangana State, India
[3] Khwaja Fareed Univ Engn & Informat Technol, Dept Math, Raheem Yar Khan, Pakistan
[4] Northwestern Polytech Univ, Sch Automat, Xian 710072, Peoples R China