[1] Univ Pitesti, Fac Elect Commun & Comp, 1 Targu Din Vale, Pitesti 110040, Romania
[2] Univ Politehn Bucuresti, 313 Splaiul Independentei, Bucharest 060042, Romania
[3] Univ Basque Country UPV EHU, Fac Engn Vitoria Gasteiz, Syst Engn & Automat Control Dept, Vitoria, Spain
[4] Gazi Univ, Fac Technol, Dept Elect & Elect Engn, TR-06500 Ankara, Turkey
[5] King Mongkues Univ Technol North Bangkok, Sci & Technol Res Inst, Bangkok, Thailand