[1] Tshwane Univ Technol, Chem Met & Mat Engn Dept, ZA-0001 Pretoria, South Africa
[2] Tshwane Univ Technol, French South African Inst Technol FSATI, Dept Elect Engn, ZA-0001 Pretoria, South Africa
[3] Ecole Super Ingenieursen Electrotech & Elect, Cite Descartes,2 Blvd Blaise Pascal, F-93160 Paris, France
[4] Tshwane Univ Technol, Inst Nanoengn Res INER, Dept Chem Met & Mat Engn, ZA-0001 Pretoria, South Africa
[5] Tshwane Univ Technol, Fac Engn & Built Environm, Dept Civil Engn, ZA-0183 Pretoria, South Africa