الفهرس 
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Abstract
lRight at the outset I wish to thank the almighty Allah with whose blessings this thesis is completed enabling me to embark on a new journey of my life.
Several people contributed to completing this thesis and they deserve my gratitude and a word of thanks. First, it is my pleasure to express my love and gratitude to my parents whose encouragement, support and motivation has always been at my side in all stages of my life. My parents are participants in all the success that I accomplish in my life
This work would not have been complete without the consistent guidance and support from my advisor, Prof. Hawaf Abd alhakiem. I received very timely help and advice during all the stages of this thesis.
My wholehearted thanks are also due to Dr. Wael Hassan Gomaa, for his valuable help and contribution. Last but not least, I am greatly indebted to my Family who provided me a constant and unyielding support without much complaints or grievances which paved a smooth way for me to complete my thesis.
Last but not least, I am greatly indebted to my devoted wife Mona and my brother Ahmed. Their continues and strong support without any complaint or regret has enabled me to complete this Ph.D thesis.