1. Institute of Industrial Ecology UB RAS; Ural Federal University; Yekaterinburg Russia
2. Department of Mathematics, College of Sciences; King Saud University; Riyadh Saudi Arabia
3. Department of Automation Engineering; TEI of Sterea Hellas; Psachna Greece
4. Section of Mathematics, Department of Civil Engineering; Democritus University of Thrace; Xanthi Greece