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Search Results: 1 - 10 of 6911 matches for " Samir Chandra Ray "
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Combined Effects of Centrifugal and Coriolis Instability of the Flow through a Rotating Curved Duct with Rectangular Cross Section  [PDF]
Rabindra Nath Mondal, Samir Chandra Ray, Shinichiro Yanase
Open Journal of Fluid Dynamics (OJFD) , 2014, DOI: 10.4236/ojfd.2014.41001
Abstract: Combined effects of centrifugal and coriolis instability of the flow through a rotating curved duct with rectangular cross section have been studied numerically by using a spectral method, and covering a wide range of the Taylor number  for a constant Dean number. The rotation of the duct about the center of curvature is imposed in the positive direction, and the effects of rotation (Coriolis force) on the flow characteristics are investigated. As a result, multiple branches of asymmetric steady solutions with two-, three-and multi-vortex solutions are obtained. To investigate the non-linear behavior of the unsteady solutions, time evolution calculations as well as power spectrum of the unsteady solutions are performed, and it is found that the unsteady flow undergoes through various flow instabilities in the scenario “chaotic → multi-periodic → periodic → steady-state”, if Tr is increased in the positive direction. The present results show the characteristics of both the secondary flow and axial flow distribution in the flow.
A Technique to Choose the Proper Vector Space Models of Semantics in Case of Automatic Text Categorization
Sukanya Ray,Nidhi Chandra
International Journal of Modern Education and Computer Science , 2012,
Abstract: vides a proper solution to this limitation. There are broadly three main categories of Vector Space Model: term-document, word-content and pair-pattern matrices. The main aim of this paper is to discuss broadly the three main categories of VSM for semantic analysis of texts and make proper selection for automatic categorizing. The scenario taken up here is categorization of research papers for organizing a national or an international conference based on the proposed methodology. Computers do not understand human language and this makes it difficult when human wants the computer to do some specific task like categorization according to human need. Vector Space Model (VSM) for semantic analysis of texts and make proper selection of one of the three main categories for automatic categorizing of research papers for organizing a national or an international conference based on the proposed methodology.
Domain Based Ontology and Automated Text Categorization Based on Improved Term Frequency – Inverse Document Frequency
Sukanya Ray,Nidhi Chandra
International Journal of Modern Education and Computer Science , 2012,
Abstract: In recent years there has been a massive growth in textual information in textual information especially in the internet. People now tend to read more e-books than hard copies of the books. While searching for some topic especially some new topic in the internet it will be easier if someone knows the pre-requisites and post- requisites of that topic. It will be easier for someone searching a new topic. Often the topics are found without any proper title and it becomes difficult later on to find which document was for which topic. A text categorization method can provide solution to this problem. In this paper domain based ontology is created so that users can relate to different topics of a domain and an automated text categorization technique is proposed that will categorize the uncategorized documents. The proposed idea is based on Term Frequency – Inverse Document Frequency (tf -idf) method and a dependency graph is also provided in the domain based ontology so that the users can visualize the relations among the terms.
Osmolyte modulated enhanced rice leaf catalase activity under salt-stress  [PDF]
Sushmita Sahu, Priyanka Das, Mamata Ray, Surendra Chandra Sabat
Advances in Bioscience and Biotechnology (ABB) , 2010, DOI: 10.4236/abb.2010.11006
Abstract: Change in catalase activity was examined in leaves of rice plant exposed to salinity. Depending on the method of preparation of crude protein extract from leaf and the constituents of the assay medium, a significant difference in enzyme activity was recorded. Inclusion of sorbitol or mannitol or sucrose in the extraction and enzyme assay medium enhanced the enzyme activity in salt-stressed samples by nearly 1.5-1.8 fold, compared to the activity found in un- stressed plants, which otherwise showed a 50% declined activity in leaf extract prepared in buffer solution and assayed in a medium depleted of these sugars. In view of the accumulation of osmolytes under saline condition, these observations suggest that the catalase activity is modulated by the osmolytes and maintains a high rate of hydrogen peroxide scavenging property in vivo and serves as the major antioxidant enzyme to scavenge the salt-induced formation of peroxide. Therefore, the salt-stress induced appearance of low activity of the enzyme under normal buffer extraction and assay conditions, as reported in literature may represent an apparent than for its real in vivo activity.
Implication of low temperature and sonication on electrocrystallization mechanism of Cu thin films: a kinetics and structural correlation
Mallik, Archana;Ray, Bankim Chandra;
Materials Research , 2013, DOI: 10.1590/S1516-14392013005000009
Abstract: the effect of an ultrasonic environment during electrodeposition of copper on graphite at various electrolyte temperatures of 25, 20, 15, 10 and 5 °c is reported in this investigation. resulting cu deposits formed by potentiostatic deposition were characterized by electrochemical methods, scanning electron microscopy and atomic force microscopy. it was found that in presence of ultrasound the deposition kinetics was mainly dominated by the charge transfer. copper nucleated according to 3d instantaneous mechanisms for all temperature ranges. the extent of nucleation was found to be increased at low temperatures. diffusion coefficients and nuclei population density were calculated for each temperature range. sonicated deposits with good surface coverage were found to consist of spherical copper agglomerates of nanosized particles.
Cadmium Telluride (CdTe) Thin Film for Photovoltaic Applications
Sekhar Chandra Ray,Kaushik Mallick
International Journal of Chemical Engineering and Applications , 2013, DOI: 10.7763/ijcea.2013.v4.290
Abstract: Cadmium telluride (CdTe) thin films are prepared by the dip-coating deposition technique under atmospheric pressure at different temperature. The optical band gap obtained within the range 1.63-1.60 eV. Crystallite sizes are obtained from XRD that are dependent on composition (Cd/Te) and baking temperatures. Raman spectra confirms the presence of transverse (TO) and longitudinal (LO) optical phonons in the CdTe structure. Films are good photoconductive in nature and could be used in photovoltaic applications.
A Study of Computer-Based Simulations for Nano-Systems and their types
Tamal Sarkar,Samir Chandra Das,Ardhendu Mandal
Physics , 2011,
Abstract: In most of the cases, the experimental study of Nanotechnology involves high cost for Laboratory set-up and the experimentation processes were also slow. So, one cannot rely on experimental nanotechnology alone. As such, the Computer-Based molecular simulations and modeling are one of the foundations of computational nanotechnology. The computer based modeling and simulations were also referred as computational experimentations. In real experiments, the investigator doesn't have full control over the experiment. But, in Computational experimentation the investigator have full control over the experiment. The accuracy of such Computational nano-technology based experiment generally depends on the accuracy of the following things: Intermolecular interaction, Numerical models and Simulation schemes used. Once the accuracy of the Computational Scheme is guaranteed one can use that to investigate various nonlinear interactions whose results are completely unexpected and unforeseen. Apart from it, numerical modeling and computer based simulations also help to understand the theoretical part of the nano-science involved in the nano-system. They allow us to develop useful analytic and predictive models. In this paper, a brief study of Computer-Based- Simulation techniques as well as some Experimental result obtained using it were given.
Dissipative tunneling in presence of classical chaos in a mixed quantum-classical system
Bidhan Chandra Bag,Bikash Chandra Gupta,Debshankar Ray
Physics , 1999, DOI: 10.1016/S0375-9601(99)00174-7
Abstract: We consider the tunneling of a wave packet through a potential barrier which is coupled to a nonintegrable classical system and study the interplay of classical chaos and dissipation in the tunneling dynamics. We show that chaos-assisted tunneling is further enhanced by dissipation, while tunneling is suppressed by dissipation when the classical subsystem is regular.
A simple semiclassical approach to Kramers' problem
Jyotipratim Ray Chaudhuri,Bidhan Chandra Bag,Deb Shankar Ray
Physics , 1999, DOI: 10.1063/1.480449
Abstract: We show that Wigner-Leggett-Caldeira equation for Wigner phase space distribution function which describes the quantum Brownian motion of a particle in a force field in a high temerature, Ohmic environment can be identified as a semiclassical version of Kramers' equation. Based on an expansion in powers of $\hbar$ we solve this equation to calculate the semiclassical correction to Kramers' rate.
Chaos and information entropy production
Bidhan Chandra Bag,Jyotipratim Ray Chaudhuri,Deb Shankar Ray
Physics , 1999, DOI: 10.1088/0305-4470/33/47/301
Abstract: We consider a general N-degree-of-freedom nonlinear Hamiltonian system which is chaotic and dissipative and show that the origin of chaotic diffusion lies in the correlation of fluctuation of linear stability matrix for the equation of motion of the dynamical system whose phase space variables behave as stochastic variables in the chaotic regime. Based on a Fokker-Planck description of the system and an information entropy balance equation a relationship between chaotic diffusion and the thermodynamically-inspired quantities like entropy production and entropy flux is established. The theoretical propositions have been verified by numerical experiments.
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