Directeur(s) de Thèse:

With immense pleasure, I acknowledge the help, guidance and support received from various quarters during the course of my PhD studies. Pursuit of PhD degree is a long journey which is very hard to accomplish without the help of others. One of the joys of completion is to look over the journey past and remember all the friends and family who have helped and supported me along this long but fulfilling road. Hence, I hereby express my appreciation to one and all. My sincere and unbounded gratitude to my advisor Christian Fraboul and co-advisors, Jean-Luc Scharbarg and Jérôme Ermont for their support and guidance. Their vision and suggestions throughout the thesis period, from choosing the problem, solving it and its presentation, has been fundamental in completion of the thesis. The joy and enthusiasm they have for the research, was contagious and motivational for me, even during tough times. Sir, you have been a source of motivation throughout. I am also very grateful to the remaining members of my dissertation committee: Professor Guy JUANOLE president of the jury, Jean-Jacques LESAGE and M. Thierry DIVOUX, my honorable reporters, Mme AUGE-BLUM Isabelle and Mr Juan LOPEZ from airbus Toulouse, our industrial partner. Their academic support and input and personal cheering are greatly appreciated. Thank you all