1. Department of Mechanical and Mechatronic Engineering, Central University of Technology, Free State, Bloemfontein 9300, South Africa
2. Department of Mechanical and Mechatronic Engineering, Tshwane University of Technology, Pretoria 0183, South Africa
3. Department of Mechanical Engineering, University of South Africa, Florida Campus, Roodepoort 1709, South Africa
4. Department of Mechanical Engineering, Faculty of Engineering, and the Built Environment, Durban University of Technology, Durban 4000, South Africa