[1] Uppsala Univ, Dept Earth Sci, Cramergatan 3, S-62157 Visby, Sweden
[2] Univ Belgrade, Sch Elect Engn, Bulevar Kralja Aleksandra 73, Belgrade 11120, Serbia
[3] Univ Belgrade, Inst Mihajlo Pupin, Volgina 15, Belgrade 11060, Serbia
[4] Teesside Univ, Sch Comp Engn & Digital Technol, Middlesbrough TS1 3BX, Cleveland, England
[5] Univ Aegean, Dept Environm, Univ Hill, Lesvos 81100, Greece