Time filter

Source Type

Medinipur, India

Vidyasagar University is a state-government administered, affiliating and research university in Paschim Medinipur district of southern West Bengal, India. It offers courses at the undergraduate and post-graduate levels.It was founded by Prof. Anil Kumar Gayen. Wikipedia.

Pradhan P.,Vidyasagar University
General Relativity and Gravitation | Year: 2016

We compute the area (or entropy) product formula for a regular black hole derived by Ayón-Beato and García (Phys Rev Lett 80:5056, 1998). By explicit and exact calculation, it is shown that the entropy product formula of two physical horizons strictly depends upon the ADM mass parameter that means it is not an universal (mass-independent) quantity. But a slightly more complicated function of event horizon area and Cauchy horizon area is indeed a mass-independent quantity. We also compute other thermodynamic properties of the said black hole. We further study the stability of such black hole by computing the specific heat for both the horizons. It has been observed that under certain condition the black hole possesses second order phase transition. The pictorial diagram of the phase transition is given. © 2016, Springer Science+Business Media New York. Source

Pradhan P.,Vidyasagar University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

We examine the thermodynamic properties of inner and outer horizons in the background of Hořava-Lifshitz black hole. We compute the horizon radii product, the surface area product, the entropy product, the surface temperature product, the Komar energy product and the specific heat product for both the horizons. We show that surface area product, entropy product and irreducible mass product are universal (mass-independent) quantities, whereas the surface temperature product, Komar energy product and specific heat product are not universal quantities because they all depend on mass parameter. We further study the stability of such black hole by computing the specific heat for both the horizons. It has been observed that under certain condition the black hole possesses second order phase transition. © 2015 The Author. Source

Pradhan P.,Vidyasagar University
Classical and Quantum Gravity | Year: 2015

In this paper we investigate the equatorial causal (time-like and null) circular geodesics of the Kerr-Newman-Taub-NUT (Newman-Unti-Tamburino) black hole in four-dimensional Lorentzian geometry. The special characteristics of this black hole are that it is of Petrov-Pirani type-D and the photon trajectories are doubly degenerate principal null congruence. We derive the conditions for the existence of the innermost stable circular orbit, marginally bound circular orbit and circular photon orbit in the background of Kerr-Newman-Taub-NUT (KNTN) spacetime. The effective potential for both time-like and null cases have been studied. It is shown that the presence of the NUT parameter deforms the shape of the effective potential in contrast with the zero NUT parameter. We further investigate the energy extraction by the Penrose process for this spacetime. It is shown that the efficiency of this black hole depends on both the charge and NUT parameter. It is observed that the energy gain is maximum when the NUT parameter goes to zero value and for the maximum spin value. When the value of the NUT parameter is increasing, the energy gain is decreasing. © 2015 IOP Publishing Ltd. Source

Gauri S.S.,Vidyasagar University
Bioresource technology | Year: 2012

A comprehensive study was made on biotransformation of p-coumaric acid and 2,4-dichlorophenoxyacetic acid by an Azotobacter sp. strain SSB81. The strain was able to tolerate a high amount of both the phenolic acids and p-coumaric acid degraded maximum (50%) than 2,4-D (29%) after five days of incubation. The intermediate products during transformation have been identified and quantified using UV-Vis and LC-MS/MS analysis. Para-coumaric acid was degraded via p-hydroxybenzoic acid and protocatechuic acid, a non-oxidative pathway whereas 2,4-D via 4-chlorophenoxyacetic acid, 4-chlorophenol and 4-chlorocatechol, an oxidative pathway. The results suggest that SSB81 developed both the oxidative and non-oxidative pathway to degrade the soil accumulated phenolic acids. Thus, Azotobacter provides an advantage to reduce the toxic level of soil accumulated phenolic acids in addition to increase the soil fertility. Copyright © 2012 Elsevier Ltd. All rights reserved. Source

Sarkar B.,Vidyasagar University
Mathematical and Computer Modelling | Year: 2012

This article deals with an EOQ (Economic Order Quantity) model for finite replenishment rate where demand and deterioration rate are both time-dependent. In this model, the retailers are allowed a trade-credit offer by the suppliers to buy more items with different discount rates on the purchasing costs. During the credit period, the retailers can earn more by selling their products. The interest on purchasing cost is charged for the delay of payment by the retailers. Some of the items may deteriorate in the course of time. In this regard, the author develops an EOQ model for time varying deterioration rate. The profit function of the model is maximized. Finally, a numerical example and graphical illustrations are used to illustrate the model. © 2011 Elsevier Ltd. Source

Discover hidden collaborations