1. University of Nis, Faculty of Electronic Engineering, Nis, Serbia + University of K. Mitrovica, Faculty of Teachers Education, Leposavić, Serbia
2. University of Belgrade, Faculty of Mechanical Engineering, Belgrade, Serbia
3. University of Nis, Faculty of Electronic Engineering, Nis, Serbia
4. Instititute of Functional Nanosystems, University of Ulm, Ulm, Germany
5. North Carolina Central University (NCCU), Durham, N. Carolina, USA