Acknowledgement

I would like to take this opportunity to thank my colleagues in the University of Minnesota, Twin Cities, who have inspired me of new research ideas and encouraged me to work hard for my PhD program, in which I enjoy the challenges and hard works. First of all, I would like to express my gratitude to my advisor Professor Zhi-Quan Luo who has provided advices and guidance without any reservation as well as financial supports for my study. I would also like to thank the dissertation committee: Professor Beth Allen, Professor Georgios B. Giannakis and Professor Mostafa Kaveh for their reviews and feedbacks on my thesis. I feel unbelievably blessed that I am able to come to University of Minnesota and work with some extremely talented people. Specially, I greatly appreciate the opportunity I had to work with Dr. Ramy Gohary, with whose great collaboration I finished a major portion of my PhD research. I was also very happy to work with students from my research laboratory including Jinjun Xiao, Alireza Razavi, Jayme