Firstly, I would like to show my sincere gratitude to José Luis Casanova to trust on me and provide a great support during my PhD. Without his recommendations, advices and knowledge, this thesis would not have been possible. I would also like to thank my PhD directors Julia Sanz, Pablo Salvador and Carlos Casanova for their continuous support during this time, for their patience, motivation, and immense knowledge. Their guidance helped me in all the time of research and writing of this thesis. I could not have imagined having better advisors and mentors for my PhD study. I would like to thank to the rest of my fellow lab-mates at LATUV (Miguel and Dani) their support, the stimulating discussions about programming, encouragement and good advices during my research, what has permitted to enrich this work from various perspectives. Last but not least; I would like to thank my family: my parents and sister for supporting me to get to the point where I am today, and to my partner and friends to encourage me to keep on until this desired goal.