1. Department of Engineering Science, Babeș-Bolyai University, Traian Vuia Square 1–4, 320085 Reșița, Romania
2. Department of Business Administration Reșița, Babeș-Bolyai University, Traian Vuia Square 1–4, 320085 Reșița, Romania
3. Institute of Mechanical Engineering, Westphalian University of Applied Sciences Gelsenkirchen Bocholt Recklinghausen, Neidenburger str. 43, 45897 Gelsenkirchen, Germany