Upon finishing my Ph.D. thesis, gratitude is the strongest feeling inside of me. I would like to express my sincere appreciation to all those who have provided me with invaluable help in this process. I wish to express my greatest gratitude to my supervisor, Prof. Zinovi Rabinovich, not only for his expert guidance and scholarly advice on my research work, but also for his strong support and encouragement throughout my Ph.D. journey. His insightful comments and critical thinking always inspire me in tackling research problems. His attitude towards the academic research provides me with a good model of what a true researcher should be. Without his patient instruction and constant encouragement, I could not fulfil these research works and complete the Ph.D. study. I would like to thank all talented members in Prof. Rabinovich's team, including Rundong Wang, Ridhima Bector and Wei Qiu, for the kind help and support that made my study in NTU a wonderful time. Besides, I would like to thank my collaborators, Xinghua Qu and Lev Raizman, for their valuable feedback and precious suggestions on my research studies. Many thanks to my friends, Yanling Li and Shuyang Ding, for the joy and the encouragement they gave me. I would like to thank my Thesis Advisory Committee (TAC) members, Prof. Sinno Jialin Pan and Dr. Fedor Duzhin, for their insightful comments and suggestions on my research work. I also want to thank Mr. Kesavan Asaithambi for his support in Computational Intelligence Lab.Most importantly, I would like to thank my parents, Zhaoxin Xu and Jiaojun Han, for their unconditional love and support throughout my life. I would like to express special thanks to my husband and best friend, Hantao Huang, for always being there for me and supporting me at all times. Having you in my life makes me feel incredibly lucky every single day. This thesis is dedicated to all of you.