Dedication To the memory of my father and my uncle Mahmoud To my dearest mother who for me; the example of devotion, you never stopped encouraging me and praying for me. May God, the Almighty, preserve you and grant you health and long life. To my dear children Ibrahim, Yacine and Ilyes Adam. To my sister Hadia, to her husband Abdnour and to my dear nephews; Anis, Massi and Ines. Their support and encouragement have enabled me to achieve this goal.