Acknowledgements

I would never have been able to finish my master thesis without the guidance of my supervisor and teachers, help from friends, and support from my family. First and foremost I offer my sincerest gratitude to my supervisor, Trine-Lise Wilhelmsen, who has supported me throughout my thesis with her patience and knowledge whilst allowing me the room to work in my own way. One simply could not wish for a better or friendlier supervisor. I shall extend my thanks to Mr. Wang Xin, my previous teacher in DMU, for his kindness and help, his encouragement and effort by supporting materials for my thesis. Without him this thesis, too, would not have been completed or written. My father, Su Yongchun, in the first place is the person who led me through the process of obtaining the knowledge by showing me the joy of intellectual pursuit ever since I was a child. His love, devotion and support are my biggest treasures and keep me moving on. My mother was the one who sincerely raised me with her caring and gently love, thanks for the warmth gains from heart whenever I think about her. Su Biquan, Su Yaosen, and Su Birong, thanks for being supportive and caring siblings