Acknowledgements

brought me into the field of granular materials, and taught me both the knowledge itself and the philosophy of how to conduct scientific research professionally and precisely. I appreciate all her contributions of time, ideas, and funding to make my Ph.D. experience productive and stimulating. Each time when I struggled in my research, her creative, constructive and invaluable guidance and ideas always encouraged and inspired me so much. All of these not only were critical for finishing my thesis and degree, but also are magnificently beneficial for my professional career as a researcher. Further, I would like to show my appreciation for Prof. Hill’s invaluable support in all aspects of my life in Minnesota. I still remember and appreciate for her precious help as a kind friend, when I first came and settled down in Minnesota as a foreigner. I am also grateful to my committee members: Prof. Lev Khazanovich, Prof. Vaughan Voller and Prof. James Kakalios for their time, interest, and helpful comments, which were very valuable for the completeness of my thesis. I would also like to thank the other member of my preliminary oral defense committee, Prof. Fernando Porte-Agel, for his time and insightful questions. I would also like to thank the former and current fellow students in Prof. Hill’s re