The Indian tiger (Panthera tigris tigris Linn. 1758), one of the world's most endangered umbrella carnivore species, is now thought to be in the verge of extinction in the wild. Sariska National Park in India is considered to be a highly suitable habitat for the tigers. However, in 2005, due to extensive poaching there were no tigers left in this park. There is some hope of further relocation of tigers from other parts of India in order to conserve them well under the prevailing conditions. The aim of the study is to model the tiger habitat suitability with the current human impacts with integrated Geospatial technology. Our study used topographical and anthropogenic variables to construct a habitat suitability model for tigers in this park. According to our model, there are areas of suitable habitat for tigers within the park. The corresponding weights for the parameters are defined by knowledge-based approach determined by field study and literature survey and thereafter by applying MCDA where AHP (crisp and fuzzy) is applied. The resulting weights imported in GIS mode and the map obtained from MCDA model in GIS shows the optimum location for the site suitability for the tiger.

Using Monte Carlo simulation we have investigated a classical two-dimensional XY-model with a modified form of interaction which makes the potential well sharper than that in the conventional XY-model. The conventional XY-model is known to exhibit a defect-mediated continuous phase transition while the modified XY-model has a strong first order phase transition, both transitions being temperature driven. Performance and relative assessment of Wang-Landau (WL) algorithm in these class of models have been discussed. Difficulties faced in simulating relatively large continuous systems using WL algorithm have been investigated. Besides applying the cluster algorithm of Wolff, we have used Ferrenberg-Swendsen multiple histogram reweighting technique and finite size scaling rules of Lee and Kosterlitz. We have also investigated the role played by the topological defects and the factors which are responsible for the change over the nature of the phase transition from a continuous one to a strongly first order one. We have also presented a detailed study of the effect of suppression of topological defects on various physical quantities relevant to this model.