1. School of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box 11365-4563, Tehran 1417466191, Iran e-mail:
2. The George Adomian Center for Applied Mathematics, 316 South Maple Street, Hartford, MI 49057-1225 e-mail:
3. Department of Chemical Engineering, Hamedan University of Technology, P.O. Box 65155-579, Hamedan 3733165169, Iran e-mail: