I also wish to sincerely show my gratefulness and appreciation to Professor Chi Chi-Hung for his guidance and support on identifying problems, finding solutions, and constantly giving me insightful pointers when reviewing my work. It has helped me to grow as an independent researcher.In addition, I would like to also thank the thesis advisory committee members, Professor Wang Huaxiong and Assistant Professor Zhao Jun, for spending the time to review my work and providing me with valuable feedbacks and comments.Last but not least, I must thank my beloved family for their continued supports and understandings to provide me the time and space to accomplish my work.It has not been an easy journey, but with great supports, persistence and consistency, I can fulfill my pursuant of life-long learning. viii To my beloved family You will never know how high you can fly unless you spread your wings.