At the outset, I would like to express my sincere gratitude to my Supervisor, Dr Ankur Kumar Agarwal for giving me the opportunity to work in this area. It would never be possible for me to take this Ph.D. thesis to this level without his continuous support, motivation, patience and technical advice. I would not have accomplished this task. Throughout my thesis-writing period, he provided encouragement, sound advice, good teaching, good company and lots of good ideas that I would have missed without him. I would like to convey my sincere thanks to Prof. KVSM Krishna, Vice Chancellor, Prof. J.L Jain (Dean Faculty of Humanities) Prof. Rajeev Sharma, Prof. Anurag Shakya, Prof. Siddharth Jain and Prof. Saurabh Kumar for their continuous support, suggestions and encouragement for completing this thesis work. A special to thanks my family, words cannot express how grateful I am to my mothers Smt. Bina Sharma and Smt. Chitralekha Kaushik. I would like to convey a special thanks to my wife Mrs. Shikha for her unstinted support and patience as also to my daughter Raisha Sharma and my son Achyut Sharma.