I would like to thank several people who have contributed in different ways towards the work accomplished in this thesis. First and foremost, I would like to express my utmost gratitude to my supervisor, Prof. Flavio Canavero, for his encouragement, guidance, and support. His wide knowledge and insightful comments have made my candidature a truly enriching experience. I would also like to express my sincerest appreciation to my co-supervisor, Prof. Igor Stievano. His patience, motivation, and guidance have benefitted me immensely. This thesis work would not have been possible without his insightful thoughts. I would thank Dr. Paolo Manfredi and Riccardo Trinchero, for their time and efforts devoted in my research work, for the valuable suggestions and critical questions during this thesis. I also acknowledge my colleagues, Marchisio, Petrini, Fontana, Figura, Ubolli and Elisabetta, for their help and accompany in the last three years. Thanks to Dr. Sun Wen and Dr. Jiang Yanchao, for their generous help and encouragement. Finally, thanks to my best friends, Tiegang, Cunfa and Yuekun who have always been so supportive. And many thanks to my family, to my parents for their constant support in my life. To them I dedicate this thesis.