This book is dedicated to my parents and teachers who inspired me a lot .I wish to express my special thanks to Dr V Ramaraju, for his support and encouragement through out my research work like a teacher . I wish to express my sincere gratitude to Mr C Nagur sir and Mr B Ravindra reddy sir for their consistent help and encouragement to complete this work. I owe a deep sense of gratitude to all my esteemed colleagues at Gouthami Institute of Technology and Management for Women,Proddatur