We acknowledge to the Chairman (Sh. Kamal Mehta) and the
Director (Prof. (Dr.) V.K. Bhansali) of Marwar Engineering
College and Research Centre, Jodhpur for providing me laboratory
facilities during this research work. We are also thankful
to Prof. S.C. Ameta, Prof. J.S. Hundal, and Prof. A.K.
Mathur for valuable critical discussions. One of us S.L. is
thankful to the UGC for the award of JRF.