1. Professor, Dept. of Applied Mathematics, Indian School of Mines Univ., Dhanbad 826 004, India.
2. Associate Professor, Dept. of Applied Mathematics, Indian School of Mines Univ., Dhanbad 826 004, India.
3. Reader, Dept. of Mathematics, B.I.T. Mesra, Ranchi 835 215, India.
4. Ph.D. Student, Dept. of Applied Mathematics, Indian School of Mines Univ., Dhanbad 826 004, India.