[1] Quaid I Azam Univ, Dept Math, Islamabad 45320, Pakistan
[2] Riphah Int Univ, Dept Math, Islamabad 44000, Pakistan
[3] King Abdulaziz Univ, Fac Sci, Dept Math, Nonlinear Anal & Appl Math NAAM Res Grp, POB 80257, Jeddah 21589, Saudi Arabia
[4] Imperial Coll London, Dept Mech Engn, London SW7 2AZ, England
[5] Univ Engn & Technol Peshawar, Dept Mech Engn, Peshawar, Pakistan