I am also deeply grateful to my graduated seniors, Prof. Wei Yang Bryan Lim and Prof. Zehui Xiong, for their constant motivation as well as for providing the necessary information and direction. I would like to thank all my friends who are helping me along the way and the collaborators who have shared research ideas and knowledge with me.A special gratitude I give to my wife/friend, Zhou Wuyufei Faye. She is like a lighthouse, always illuminating the path ahead of me. Whenever I face the most challenging times in life, she shines a light to guide me in the right direction. At the same time, she is also a friend, constantly encouraging me and cheering me on, preventing me from getting trapped in negative emotions.