Acknowledgements
Foremost I would like to express my sincere gratitude to the supervisors of my thesis: Prof. mr. dr. A.R. Mackor, Prof. mr. dr. G. Knigge and dr. B.S. Hellemans for their continuous support of my Ph.D study and research, and for their patience, motivation and enthusiasm throughout the process of writing this work.
Furthermore, I would like to thank my parents. Their continuous patience, encouragement and, support helped me throughout the process of writing this work.