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Jalpāiguri, India

Yada N.,National Institute of Technology Durgapur | Kundu P.,National Institute of Technology Durgapur | Paul S.,Ananda Chandra College | Pal P.,National Institute of Technology Durgapur
International Journal of Non-Linear Mechanics | Year: 2016

We investigate transition to chaos in Rayleigh-Bénard convection (RBC) of low Prandtl-number fluids with free-slip boundary conditions. Detailed three dimensional direct numerical simulations (DNS) of the governing equations of RBC are performed for this purpose. DNS for Pr = 0.025 shows two possible routes to chaos, namely via period doubling route and quasiperiodic route. A low dimensional model is constructed using the DNS data and it helps us to understand the bifurcation structure associated with different routes to chaos. Bifurcation analysis of the model also shows two distinct route to chaos for Pr = 0.025, similar to DNS, viz. period doubling and quasiperiodic route to chaos. Period doubling route is associated with the periodic wavy rolls solution while the quasiperiodic route is associated with the stationary squares solutions. The results of our investigation show similarity with previous experimental observations of Fauve and Libchabar (1981) [1]. We also investigate the bifurcation structure near the onset of convection for Pr = 0.3 using the same low dimensional model. The investigation shows that the route to chaos is quasiperiodic in this case and found to match well with DNS results. © 2016 Elsevier Ltd. All rights reserved.

Patra A.K.,Ananda Chandra College | Datta T.,Ananda Chandra College
Turkish Journal of Zoology | Year: 2013

The ichthyofaunal diversity of the Karala River and its adjoining areas in the Jalpaiguri District of West Bengal was studied from February 2009 to September 2010. A total of 3 identifed species of freshwater spiny eels belonging to the order Synbranchiformes were recorded from a total of 55 captured species. During the course of the study period, the researchers collected 3 specimens that showed nearly all of the important features of Macrognathus pancalus except for the caudal fin character. Te caudal fin was entirely converged with the dorsal and anal fns. The soft dorsal fin ray characters and the number of free predorsal spines specify that they belong to Macrognathus pancalus Hamilton, 1822. They show this type of morphology due to the regeneration of the tail. © TÜBİTAK.

Datta T.,Ananda Chandra College
Turkish Journal of Zoology | Year: 2014

Results indicate resting as the main diurnal activity of Aythya nyroca, whereas feeding dominated during the night. Other than resting (56.3%), feeding (16.8%) and swimming (15.2%) were major activities of the diurnal time-activity budget, whereas preening (9.4%) and flying (2.3%) were less frequent and occupied a secondary rank. Feeding and swimming were prevalent during the morning and afternoon hours. During midday, most of the ducks indulged in resting. Te small amount of time spent on diurnal feeding was compensated by voracious nocturnal feeding (64.6%), which peaked in the middle of the night. Human interference plays an important role in shaping the diurnal time-activity budget. Ferruginous Ducks used the Gajoldoba wetland for foraging and roosting both day and night all through the wintering cycle, which proves that the Gajoldoba wetland is a stable wintering ground for Ferruginous Ducks. © TÜBİTAK.

Datta T.,Ananda Chandra College | Patra A.K.,Ananda Chandra College | Dastidar S.G.,Ananda Chandra College
Asian Pacific Journal of Tropical Biomedicine | Year: 2014

Objective: To explore traditional ethnomedicinal knowledge of different tribes of Coochbehar district of West Bengal, India, and its present status. Methods: With the help of standardized questionnaires, traditional healers and resource persons were interviewed on medicinal use of local flora in all the tribal villages of Coochbehar district during July, 2007 to December, 2009 and some of the places were revisited for this purpose again during July to December of 2012. Results: A total of 46 plant species belonging to 42 genera and 27 families were reported to be used for treating 33 various physical ailments. In terms of the number of medicinal plant species, Fabaceae (5 species) and Euphorbiaceae (4 species) are dominant families. Among different plant parts used for the preparation of medicine, leaves were most frequently used for the treatment of diseases. Conclusions: In all tribal villages we found the use of medicinal plants, particularly to treat common physical problems like smaller injuries, stomachache and abdominal disorder. However, non-availability of such plants in close vicinity is imposing restriction on using medicinal plants. Further research on these species may lead to the discovery of novel bioactive molecules in one hand and also it may open up a new horizon of sustainable development. © 2014 by the Asian Pacific Journal of Tropical Biomedicine.

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