I would like to express immense gratitude to my generous parents, my husband, my brothers and sisters who gave me courage, unconditional support and real prayers. And I would like thank my supervisor professor Dr. Ahmed Khammash for his motivation, taking time out of busy schedule and guiding me in this dissertation. Moreover I would also be thanking my classmates in Masters at Umm Al-Qura University for our cooperation and sharing our experience. Above all, I thank Allah for giving me the intellect to comprehend the subject, and for giving me the strength and endurance to complete this dissertation.