\chapter*{acknowledgements \markboth{acknowledgements}{acknowledgements}}
\label{acknowledgements}
\addcontentsline{toc}{chapter}{Acknowledgements}
+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.
+Foremost, I would like to express my sincere gratitude to all my supervisors: Prof.~Dr.~Rapha\"el~Couturier and Asst.~Prof.~Dr.~Jean-Claude Charr 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.
+
+Besides my supervisors, I would like to express my gratitude to Prof.~Dr.~Jean-Marc Pierson and Assoc~Prof.~Dr.~Fabienne Jézéquel (HDR) for accepting to review my dissertation and for their insightful and appreciated comments. I would like to thank also Prof.~Dr.~Nabil Abdennadher for accepting to participate in my dissertation committee.
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+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 University of Franche-Comté for the received support.
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+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. These include Jacques Bahi, Pierre-Cyrille Héam, Abdallah Makhoul, Jean-François Couchot, Ahmed Mostefaoui, Yousra Ahmed Fadil, Pierre Saenger, Zeinab Fawaz, Amor Lalama, Nesrine Khernane, Stéphane Domas, Mohammed Bakiri, Michel Salomon, Karine Deschinkel, Christophe Guyeux, Mourad Hakem, David Laiymani, Gilles Perrot, Christian Salim, Santiago Costarelli, Carol Habib, Hassan Moustafa Harb and Ke Du. I would like to give a special thanks for Asst.~Prof.~Dr.~Arnaud Giersch who helped me understand the simulation over SimGrid simulator.
+I would like also to thank my colleague, Dr. Ali Kadhum Idrees University of Babylon for his help. I would like to express my thanks and my best wishes to Ingrid Couturier for all the received assistance during my study.
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+Finally, I would like to thank all my friends and people who encouraged and supported me along the way.
+
