Acknowledgment
I wish to extend my sincere gratitude to the University of Calcutta and especially to personalities like Prof. Asish Dasgupta, Prof. Apurba Datta and Prof. Bijoy Banerjee, who have always been my inspiration. I am also grateful to the, Space Applications Centre (SAC-ISRO) for the support it has provided me. The courtesy extended by Dr Bijoy Roy, Dr Chandrashekhar, Mr Suman Aich, and Mr Ananya Roy of SAC by agreeing to review and comment on the early versions of the manuscript are also very much appreciated. Thanks are due to Dr Suman Ganguly of CFRSI for his kind cooperation. I also acknowledge the generous gestures of Dr M R Sivaraman, Dr Kalyan Bandyopadhyay, Mr Vilas Palsule and the whole team of the CSSTE-AP. I would also like ...