Author(s):
1. Sadoon Ayed, Faculty of Mechanical Engineering in Niš, Serbia
2. Milos Jovanovic, Faculty of Mechanical Engineering in Niš, Serbia
3. Gradimir Ilić, Faculty of Mechanical Engineering in Niš, Serbia
4. Predrag Živković, Faculty of Mechanical Engineering in Niš, Serbia
5. Mladen Tomić, The School of Higher Technical Professional Education, Niš, Serbia