1. Department of Mechanical Engineering Bourns Hall Riverside, CA USA + Department of Mathematics & Statistics, FBAS, IIU, Islamabad, Pakistan
2. Department of Mathematics & Statistics, FBAS, IIU, Islamabad, Pakistan
3. Department of Mathematics, SRB, Islamic Azad University, Tehran, Iran
4. Department of Mathematics, Quaid-i-Azam University, Islamabad, Pakistan + Department of Mathematics, College of Science, KSU, Riyadh, Saudi Arabia
5. Department of Mechanical Engineering Bourns Hall Riverside, CA USA