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7 \chapter*{acknowledgements \markboth{acknowledgements}{acknowledgements}}
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9 \addcontentsline{toc}{chapter}{Acknowledgements}
13 %First of all, I would like to offer my utmost gratitude to God, the creator of all things, and to thank him for his support and guidance to complete this journey.
15 The long journey of my Ph.D. study has finished. It is with great pleasure that I acknowledge my debts to those who have greatly contributed to the success of this dissertation. It was only through support and encouragement of many that I have been able to complete this amazing journey.
17 Foremost, I would like to express my sincere gratitude to all my supervisors: Prof.~Dr.~Rapha\"el~Couturier, Asst.~Prof.~Dr.~Karine~Deschinkel, and Asst.~Prof. Dr.~Michel~Salomon for their continuous support, encouragement, and advice they have provided throughout my Ph.D.~study. Their patience, motivation, enthusiasm, and immense knowledge taught me a lot. Their tireless guidance has helped me immensely in researching and writing this dissertation. I have been extremely lucky to have supervisors who cared so much about my work, and who responded to my questions and queries so promptly.
19 Besides my supervisors, I would like to express my gratitude to Prof.~Dr.~Ye-Qiong~Song and Assoc~Prof.~Dr.~Hamida~Seba (HDR) for accepting to review my dissertation and for their insightful and appreciated comments. I would like to thank also Prof.~Dr.~Sylvain~Contassot-Vivier for accepting to participate in my dissertation committee.
21 I would like to gratefully acknowledge the University of Babylon, Iraq for financial support as well as I would also like to express my thanks to Campus France and University of Franche-Comté for the received support.
23 My appreciation and thanks go to the members of the team AND ({\it Algorithmique Numérique Distribuée}) for the warm and friendly atmosphere in which they allowed me to work. So thank you to Jacques Bahi, Pierre-Cyrille Héam, Huu Quan Do, Bassam Alkindy, Abdallah Makhoul, Huda Al-Nayyef, Jean-Claude Charr, Jean-François Couchot, Ahmed Mostefaoui, Ahmed Fanfakh, Yousra Ahmed Fadil, Stéphane Domas, Pierre Saenger, Zeinab Fawaz, Arnaud Giersch, Christophe Guyeux, Mourad Hakem, David Laiymani, Gilles Perrot, Christian Salim, Bashar Al-Nuaimi, Santiago Costarelli, Carol Habib, Hassan Moustafa Harb, and Ke Du. I would like to express my thanks and my best wishes to Ingrid Couturier for all the received assistance during my study. I would also like to express my thanks to Dr.~Lilia~Ziane Khodja, PostDoc at $LTAS-A\&M$, Liege, Belgium. I would like to thank Béatrice Domenge and Maxim Moureaux from the {\it Reprographie service} for all received assistance during my study. I would also like to thank Patricia Py, Computer Science Department secretary. I dare not risk missing to mention anyone’s name, so I will simply say 'thank you ALL for being there for me'.
25 Last but not the least, I would like to extend a warm appreciation to those families and friends who have been encouraging along the way.