1. Dipartimento di Matematica e Informatica, Università di Catania, Viale A. Doria 6, 95125 Catania, Italy
2. RUDN University, 6 Miklukho – Maklay St, Moscow 117198, Russia
3. Department of Mechanical Engineering, Okan University, Akfirat, Tuzla, 34959 Istanbul, Turkey