Acknowledgements

I would like to take this opportunity to thank those who guided and supported me during this process. Without their contributions, this research would not have been possible. Firstly, I would like to thank my PhD advisor, Prof. Kurt Rothermel. He taught me how to undertake this research during the past years. Besides this, he was always patient and helpful whenever his guidance and assistance were needed. Prof. Rothermel also contributed much of his valuable time to help me for improving my writing skills. Furthermore, he gave advice on how to communicate and cooperate with other researchers as a professional. Therefore, I would like to show my deep appreciation to him. I am also grateful to Prof. Peter Göhner for serving on my PhD committee and spending time reviewing this work and giving valuable suggestions and comments on my work. I would like to thank Dr. Becker and Dr. Marrón for their valuable advice on my research work. I also appreciate valuable discussions with Jörg Hähner, Illya Stepanov, Jing Tian and other faculty members and students. Thei