1. Department of Mechanical and Industrial Engineering, Masinde Muliro University of Science and Technology, Kakamega, Kenya
2. Department of Mining, Materials and Petroleum Engineering, Jomo Kenyatta University of Agriculture & Technology, Nairobi, Kenya
3. School of Chemical and Metallurgical Engineering, University of Witwatersrand, Johannesburg, South Africa
4. Department of Mechanical Engineering Science, University of Johannesburg, Johannesburg, South Africa