Add to ORKGI would like to express my sincere gratitude to Dr. S. Sitharama Iyengar, my advisor, for his invaluable guidance and encouragement extended throughout the study. His tenacious supervision, helpful suggestion, patience and time deserve a special mention I would like to express my appreciation to my committee members Dr. Rajgopal Kannan and Dr. Arjan Durresi for their support and suggestions. I would also like to thank my colleagues Ankur Suri,Vatsalya Kunchakarra, Neelay Shah, Vamsi K Paruchuri, Ramaraju Kalidindi, Sasanka Madiraju for their suggestions during progress of this thesis. I thank my parents Mr. M. P. Devaiah and Mrs. Rani Devaiah and my brother Mr. Belliappa M. D., for their continued support and encouragement in the course of ...