Ang Wei Tech, for his invaluable guidance and insightful suggestions throughout my Ph.D. study at Nanyang Technological University. He always encouraged me and provided generous support every time I got lost, not only in my research but also in daily life. His enthusiasm and optimism for research and work keep inspiring me to live a meaningful life, both now and in the future.Secondly, I would like to sincerely express my appreciation to my thesis advisory committee, Prof. Lum Guo Zhan, for his warm help in my exploration of several research projects and valuable sharing of study and life, and Prof. Hu Guoqiang for his kind advice on my research progress.Many thanks also go to my fellow teammates,