Gujarat Arts and Science College

Ahmadābād, India

Gujarat Arts and Science College

Ahmadābād, India
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Kataria H.R.,M. S. University of Baroda | Mittal A.S.,Gujarat Arts And Science College
Applied Thermal Engineering | Year: 2017

The present paper is concerned with the mathematical modeling of flow, heat and mass transfer in the unsteady natural convection magneto hydrodynamic flow of electrically conducting nano fluid, past over an oscillating vertical plate. The bounding plate has ramped temperature with ramped surface concentration and isothermal temperature with ramped surface concentration profile through porous medium. The governing non-dimensional system of partial differential equations with initial and boundary condition are solved analytically using Laplace transform. The features of the fluid flow, heat and mass transfer characteristics are analyzed by plotting graphs and the physical aspects are discussed in detail. With the help of velocity, temperature and concentration, Skin friction, Nusselt number and Sherwood number are derived and represented through tabular form. © 2016 Elsevier Ltd


Vachhani M.G.,Gujarat Arts and Science College | Vachhani M.G.,Gujarat University | Gajjar P.N.,Gujarat University
AIP Conference Proceedings | Year: 2016

A state of art model for thermal transistor is proposed using three FK 1D chains. In this paper we study how control over heat transfer in nanoscale materials be achieved using microscopic model of thermal transistor. We study the influence of spring constant of source segment on the switching efficiency, thermal amplification and working region of the thermal transistor. We found the increase in switching efficiency and thermal amplification where as decrease in working region with increase in spring constant of source segment. © 2016 Author(s).


Prajapati S.P.,Gujarat Arts and Science College | Prajapati S.P.,University of Rajasthan | Patel D.P.,Gujarat Arts and Science College | Patel D.P.,University of Rajasthan | Patel P.S.,Sheth Lh Science College
Journal of Chemical and Pharmaceutical Research | Year: 2012

6-amino-4-(substitutedphenyl)-1-(2,4-dinitrophenyl)-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile have been prepared by the refluxation for five hours of 2-(2,4-dinitrophenyl)-5-methyl-2,4-dihydro-pyrazol-3-one, malononitryle, substitutedbenzaldehyde and piperidine in presence of ethanol the intermediate 2-(2,4- dinitrophenyl)-5-methyl-2,4-dihydro-pyrazol-3-one synthesized by the condensation of Ethyl acetoacetate and 2,4- di-Nitro Phenyl Hydrazine. The synthesized compounds were characterized by means of their IR, 1 H-NMR spectral data and elemental analysis. All the synthesized products were evaluated for their antimicrobial activities by Cup borer method.


Deheri G.M.,Sardar Patel University | Patel R.M.,Gujarat Arts and Science College
Meccanica | Year: 2010

An endeavor has been made to discuss the behavior of hydromagnetic squeeze film between two conducting rough porous conical plates. The plates are considered to be electrically conducting and the clearance space between them is filled by an electrically conducting lubricant. A transverse magnetic field is applied between the plates. Efforts have been made to solve the concerned Reynolds' equation with the associated boundary conditions to get the pressure distribution. This in turn, is used to obtain the expression for load carrying capacity leading to the calculation of the response time. The results are presented graphically as well as in tabular form. It is suggested by the results that the bearing system records an enhanced performance as compared to that of a bearing system working with a conventional lubricant. It is noticed that the pressure, load carrying capacity and the response time increase steadily with increasing values of the magnetization parameter. In general, the bearing suffers owing to transverse surface roughness. However, the negatively skewed roughness tends to better the performance of the bearing system marginally. This performance gets further improved especially, when the negative variance is involved. It is observed that the semi-vertical angle increases the load carrying capacity. Besides, the conductivity also increases the load carrying capacity significantly. In addition, it is revealed that the negative effect induced by the porosity can be neutralized to a nominal extent by the positive effect of the magnetization parameter in the case of negatively skewed roughness in the presence of negative variance. Thus, this study provides ample scopes for improving the performance of the bearing system considerably by choosing a suitable combination of magnetization parameter, semi-vertical angle and the conductivities of the plates. © 2010 Springer Science+Business Media B.V.


Patel R.M.,Gujarat Arts and Science College | Deheri G.M.,Sardar Patel University | Vadher P.A.,Government Science College
Tribology in Industry | Year: 2010

Efforts have been made to study and analyze the effect of transverse surface roughness on the performance of a magnetic fluid based squeeze film between triangular plates. The roughness of the bearing surfaces is characterized by a stochastic random variable with non-zero mean variance and skewness. The associated Reynolds' equation is stochastically averaged with respect to the random roughness parameter in turn, which is solved with appropriate boundary conditions to obtain the pressure distribution. From this, the expression for load carrying capacity is derived. The results suggest that the magnetization parameter increases the load carrying capacity while the load carrying capacity gets decreased due to the standard deviation. It is seen that the negatively skewed roughness increases the load carrying capacity substantially especially, when the negative variance is involved. It is revealed that the negative effect induced by the standard deviation can be minimized by the positive effect of the magnetization parameter in the case of negatively skewed roughness.


Deheri G.M.,Sardar Patel University | Patel R.M.,Gujarat Arts and Science College | Abhangi N.D.,Marwadi Education Foundations Group of Institutions
Industrial Lubrication and Tribology | Year: 2011

Purpose - This paper aims to improve upon the performance of magnetic fluid-based squeeze film between transversely rough curved annular plates by embarking on a comparative study of the geometrical structure of the curved annular plates. Design/methodology/approach - The objectives are met by mathematically modeling a magnetic fluid-based squeeze film between transversely rough curved annular plates. The standard method is to solve the associated Reynolds' equation with appropriate boundary conditions by describing the random roughness through a stochastic random variable with non-zero mean, variance and skewness. Results for bearing performance characteristics such as pressure distribution and load-carrying capacity are numerically computed. In order to analyze the quantitative effect of the roughness, different geometrical structures of surfaces have been considered and the results are compared. Findings - Certainly, the performance of the bearing with the magnetic fluid lubricant is comparatively better than the conventional lubricant. The findings indicate that although the effect of roughness is adverse in general, the adverse effect introduced by roughness and aspect ratio can be compensated for, to a considerable extent, by the positive effect of magnetization parameter in the case of negatively skewed roughness by choosing the curvature parameters properly. Practical implications - From the industry point of view, this investigation will be definitely useful for improving the performance of the squeeze film based on magnetic fluid between transversely rough curved annular plates by minimizing the effect of roughness. Furthermore, it offers an additional degree of freedom from a design point of view in the form of the geometrical structure of the surfaces. Originality/value - The paper presents significant information as it compares shapes and offers suggestions for the best improved performance from a bearing's longevity point of view. This study presents an approach for the enhanced performance of the magnetic fluid-based squeeze film between transversely rough curved annular plates. © 2011 Emerald Group Publishing Limited.


Patel R.M.,Gujarat Arts and Science College | Deheri G.M.,Sardar Patel University | Vadher P.A.,Government Science College
Acta Polytechnica Hungarica | Year: 2010

An effort has been made to study and analyze the performance of a magnetic fluid based infinitely short hydrodynamic slider bearing. The Reynolds' equation is solved with appropriate boundary conditions. The expressions for various performance characteristics such as pressure, load carrying capacity and friction are obtained. Results are presented graphically. It is clearly seen that the load carrying capacity increases considerably due to the magnetic fluid lubricant. Further, the film thickness ratio increases the load carrying capacity. It is found that the load carrying capacity increases as the ratio of the length to outlet film thickness increases while it decreases with respect to the increasing values of the ratio of the width to the outlet film thickness. In addition, it is investigated that the magnetic fluid lubricant unalters the friction. Lastly, this article makes it clear that the negative effect induced by the ratio of the width to the outlet film thickness can be neutralized up to a considerably large extent by the combined positive effect of the magnetization parameter, the film thickness ratio and the ratio of the length to outlet film thickness. This study provides ample scope for extending the life period of the bearing system.


Patel R.M.,Gujarat Arts and Science College | Deheri G.,Sardar Patel University | Patel H.C.,Sardar Patel University
Acta Polytechnica Hungarica | Year: 2011

An endeavor has been made to investigate the performance of a magnetic fluid based squeeze film between rough circular plates while the upper plate has a porous facing of variable porous matrix thickness. The bearing surfaces are transversely rough. The random roughness of the bearing surfaces is characterized by a random variable with non-zero mean, variance and skewness. The associated Reynolds' equation is stochastically averaged with respect to the random roughness parameter and is solved with appropriate boundary conditions. The results for bearing performance characteristics such as pressure, load carrying capacity and response time for different values of mean, standard deviation and measure of symmetry are numerically computed and presented graphically. First of all it is observed that these performance characteristics increase with the increasing magnetization parameter thereby, suggesting that the performance of the bearing with magnetic fluid lubricant is better than that with the conventional lubricant. It is noticed that the bearing suffers owing to transverse surface roughness. However, the negatively skewed roughness tends to increase the load carrying capacity. Moreover, there is a very significant observation that with a proper selection of the thickness ratio parameter a magnetic fluid based squeeze film bearing with variable porous matrix thickness in the case of negatively skewed roughness can be made to perform considerably better than that of a conventional porous bearing with an uniform porous matrix thickness working with a conventional lubricant. In addition, this article makes it clear that by choosing properly the thickness ratio parameter and the strength of the magnetic field, the adverse impact induced by roughness on the bearing system can be minimized in the case of negatively skewed roughness especially when negative variance occurs. Thus, this study makes it mandatory to account for roughness while designing the bearing system.


Joshi J.S.,Gujarat University | Bhatt M.B.,Gujarat Arts and Science College
Proceedings - 2012 IEEE International Conference on Technology Enhanced Education, ICTEE 2012 | Year: 2012

The dawn of the twenty first century has witnessed unprecedented development in technology. Competition in every field in the era of globalization, liberalization and privatization has boosted the use of technology including IT applications. Physically normal person adopts technology easily whereas for the physically challenged person it requires special efforts. Advancement in technology is also required to make them techno savvy. Scientific and technological progress of the last few decades has brought not only the economy globalization and worldwide expansion of technologies but changes in social relations, culture, and education as well. Fast development of telecommunications, media, and information technologies bears huge potential of improving the quality of life. It is very important for those, who cannot obtain an appropriate level of education without assistance of educational and technology specialists, i.e. people with special educational needs. Technological advance has unveiled meaningful social opportunities for such citizens by providing a more convenient access to information and communication tools. Thereby, it gives a chance to enhance skills and involve everyone in active social life. © 2012 IEEE.


Vachhani M.G.,Gujarat Arts and Science College | Vachhani M.G.,Gujarat University | Patel T.K.,Gujarat University | Gajjar P.N.,Gujarat University
International Journal of Thermal Sciences | Year: 2016

We study an in-depth operation of a microscopic model of thermal transistor consisting of Fermi - Pasta - Ulam - β like lattices. The output and the transfer characteristics of thermal transistor have been reported, which are very analogous to its counterpart characteristics of an n-channel FET. Here, we coined and identified terminology like thermal Fourier region, thermal knee point, thermal pinch-off point and thermal saturation region from output characteristics of thermal transistor. Thermal source resistance, thermal transconductance and thermal amplification factor have been defined and computed for different gate temperatures. Our non-equilibrium molecular dynamics simulation study shows an amplification of output thermal current ≈ 218 times with thermal transconductance 0.0164 ± 0.0007. First ever equation for output thermal current JS = JSS[1-TGS/TP]2 is numerically established which is very analogous to that of Shockley's equation for FET. © 2016 Elsevier Masson SAS.

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