1. Department of Electrical Engineering and Industrial Informatics, Politehnica University Timisoara 1 , Piata Victoriei Nr. 2, Timis, Timisoara, Romania
2. Cooperativa TEC 2 , 439 Via Nazionale, Pellaro, 89134 Reggio Calabria, Italy
3. Engineering Faculty of Hunedoara, Politehnica University Timisoara 3 , Revolutiei 5, Hunedoara, Romania