Author(s):
1. Miloš Madić, Serbia
2. Miroslav Radovanović, Faculty of Mechanical Engineering in Niš, Serbia
3. Srđan Mladenović, Faculty of Mechanical Engineering in Niš, Serbia
4. Dušan Petković, Faculty of Mechanical Engineering in Niš, Serbia
5. Predrag Janković, Faculty of Mechanical Engineering in Niš, Serbia