1. Department of Mathematics, College of Sciences; King Saud University; P. O. Box 2455 Riyadh 11451 Saudi Arabia
2. Group Leader, Group of Modern Computational Methods; Ural Federal University; 19 Mira Street Ekaterinburg 620002 Russia
3. Department of Automation Engineering; TEI of Sterea Hellas; Psachna GR 34400 Greece
4. Section of Mathematics, Department of Civil Engineering; Democritus University of Thrace; Xanthi Greece