Acknowledgement

My deepest gratitude belongs to my supervisor, Prof. Chu-ren Huang.Without his guidance and support, this work can never be finished.I also appreciate the discussions with our teammates.Their words inspired me a lot in many ways.The suggestions from anonymous reviewers push me to improve the work in details.I owe them many thanks.My dearest editors, Rebecca from Springer Nature, and Ling Li from Peking University Press, offers me great patience and endless help.I sincerely thank them and everyone working for this book unknown to me.In the end, I would like to thank my family and friends, for encouraging me all along the way.

Any mistakes in this book, of course, are mine. And I would be more than grateful to any discussions for improvements, corrections, questions or comments.