The author expresses deep gratitude to several mentors and colleagues who supported the completion of their research. Specifically, the author thanks Dr. Fr. S. JOHN BRITTO, their mentor and guide, for his dedication and advice which helped the author accomplish their task. The author also thanks Dr. S. SENTHIL KUMAR for their interest, inspiration, and timely suggestions. Finally, the author expresses gratitude to friends, family members, and staff who provided encouragement and assistance throughout the research period.