1. Department of Industrial Engineering, Tshwane University of Technology, Staatsartillerie Rd, Pretoria West, Pretoria
2. Department of Industrial and Manufacturing Systems, National University of Science and Technology, Bulawayo, Zimbabwe
3. Department of Operations Management, Tshwane University of Technology, Staatsartillerie Rd, Pretoria West, Pretoria
4. Department of Production Engineering, KTH Royal Institute of Technology, Brenellvagen, Stockholm Sweden