Author(s):
1. Marko Mancic, Faculty of Engineering, University of Kragujevac, Sestre Janjić 6, 34000 Kragujevac, Srbija 2IMW Ins, Serbia
2. Dragoljub Živković, Faculty of Mechanical Engineering in Niš, Serbia
3. Velimir Stefanovic, Faculty of Mechanical Engineering in Niš, Serbia
4. Vladana Stanković, Faculty of Civil Engineering and Architecture in Niš, Serbia
5. Goran Jovanović, Faculty of Civil Engineering and Architecture in Niš, Serbia