Add to ORKGFirstly, I would like to thank God for giving me the talent to go this far. I would like to sincerely thank Professor Agnes van Dyk of the University of Namibia for her guidance and words of encouragement during my studies, and for being a model in my academic life. I dedicate this Doctorate degree to you as a retirement gift, Prof! Thanks to Dr Marieta van der Vyver for your support. Thanks to all my friends and Aunt Susanna for your support during my orphanage times. Special thanks to Professor Marie Poggenpoel and Professor Chris Myburg. Thank you for your consultations and guidance “at times when there was salad in my mind”. Thank you for guiding me towards 3D (three dimensional) thinking. Sincere thanks to Dr Richard Tachere for indepe...