1. Department of Science and Humanities, R. M. D. Engineering College, Kavaraipettai, Tamil Nadu 601 206, S. India
2. Department of Mathematics and Institute for Mathematical Research, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia
3. Department of E.E.E, R. M. K. College of Engineering and Technology, Puduvoyal, Tamil Nadu 601 206, S. India