Wyniki wyszukiwania - BazTech

1

Synthesis and characterization of Ag-chalcogenide nanoparticles for possible applications in photovoltaics

Chand S., Sharma P.

Materials Science Poland

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2018

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Vol. 36, No. 3

375--380

EN

Bottom-up technique has been used to synthesize Ag-chalcogenide nanoparticles. This work reports on the synthesis of Ag2Se by varying the molar ratio of capping agent and pH of the solution. The synthesized nanoparticles have been characterized in terms of structural parameters using X-ray diffraction. By this technique, various parameters such as crystallite size, dislocation density and strain of the nanoparticles were calculated. The crystallite size decreased with the increase in pH of the solution. The optical characterization was carried out by UV-Vis-NIR spectrophotometer. With the decrease in the crystallite size, a blue shift in the absorption peak of the nanoparticles was observed. These properties are suitable for energy harvesting with the help of photovoltaics.

2

Polyaniline: tin oxide polymeric nanocomposite films. An electrical and dielectric study

Arora R., Chand S., Sharma P.

Materials Science Poland

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2018

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Vol. 36, No. 4

711-716

EN

A conducting nanocomposite film of 60 nm nano-SnO2-polyaniline (PANI) and polyvinyl alcohol (PVA) has been synthesized and analyzed in terms of AC conductivity and dielectric behavior. The conducting polymer nanocomposite of PANI/60 nm (SnO2) and polyvinyl alcohol (PVA) has been prepared via in situ polymerization technique. The morphology of the nanocomposite film has been studied by SEM. The film has been characterized in terms of DC conductivity. The dielectric behavior and AC conductivity of the nanocomposite film have been investigated in the frequency range of 2 Hz to 90 KHz. The film has high dielectric constant which may be correlated with polarization. It has been observed that both dielectric loss and dielectric constant decrease with an increase in frequency.

3

Flow behavior in weakly permeable micro-tube with varying viscosity near the wall

Gupta R. R., Kumar V., Chand S.

Polish Journal of Chemical Technology

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2017

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Vol. 19, nr 4

16--21

EN

Weakly permeable micro-tubes are employed in many applications involving heat and/or mass transfer. During these processes, either solute concentration builds up (mass transfer) or steep change in temperature (heat transfer) takes place near the permeable wall causing a change in the viscosity of the fluid. Results of the present work suggest that such change in viscosity leads to a considerable alteration in the flow behavior, and the commonly assumed parabolic velocity profile no longer exists. To solve the problem numerically, the equation of motion was simplified to represent permeation of incompressible, Newtonian fluid with changing viscosity through a micro-tube. Even after considerable simplification, the accuracy of the results was the same as that obtained by previously reported results for some specific cases using rigorous formulation. The algorithm developed in the present work is found to be numerically robust and simple so that it can be easily integrated with other simulations.

4

Triple- diffusive convection in a micropolar ferrofluid in the presence of rotation

Chand S.

International Journal of Applied Mechanics and Engineering

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2013

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Vol. 18, no. 2

307--327

EN

This paper deals with the theoretical investigation of the triple-diffusive convection in a micropolar ferrofluid layer heated and soluted below subjected to a transverse uniform magnetic field in the presence of uniform vertical rotation. For a flat fluid layer contained between two free boundaries, an exact solution is obtained. A linear stability analysis theory and normal mode analysis method have been employed to study the onset convection. The influence of various parameters like rotation, solute gradients, and micropolar parameters (i.e., the coupling parameter, spin diffusion parameter and micropolar heat conduction parameter) on the onset of stationary convection has been analyzed. The critical magnetic thermal Rayleigh number for the onset of instability is also determined numerically for sufficiently large value of the buoyancy magnetization parameter M1 (ratio of the magnetic to gravitational forces). The principle of exchange of stabilities is found to hold true for the micropolar fluid heated from below in the absence of micropolar viscous effect, microinertia, solute gradient and rotation. The oscillatory modes are introduced due to the presence of the micropolar viscous effect, microinertia , solute gradient and rotation, which were non-existent in their absence. In this paper, an attempt is also made to obtain the sufficient conditions for the non-existence of overstability.

5

Thermosolutal convection in Walter's (model B') fluid in porous medium in hydromagnetics.

Sunil D., Sharma R.C., Chand S.

Studia Geotechnica et Mechanica

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2000

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Vol. 22, nr 3-4

3-14

EN

The thermosolutal convection in Walters" (Model B') fluid in porous medium is considered in the presence of uniform vertical magnetic field. For the case of stationary convection, that solute gradient and magnetic field have stabilizing effects on the system, whereas the medium permeability has destabilizing effect on the systems. The kinematic viscoelasticity has no effect on stationary convection. The kinematic viscoelasticity, stable solute gradient and magnetic field introduce oscillatory modes into the system, which are non-existent in their absence. The sufficient conditions for the avoidance of over stability are also obtained.

PL

Opisano konwekcję substancji rozpuszczonych termicznie w płynie Waltera (model B') w ośrodku porowatym w obecności jednorodnego, pionowego pola magnetycznego. W przypadku ustalonej konwekcji stały gradient substancji rozpuszczonej i pole magnetyczne stabilizują układ, podczas gdy przepuszczalność ośrodka go destabilizuje. Lepkosprężystość kinematyczna nie ma wpływu na ustaloną konwekcję. Kinematyczna lepkosprężystość, ustalony gradient substancji rozpuszczonej i pole magnetyczne wprowadzają do układu oscylacyjne fale elektromagnetyczne, których w przeciwnym razie brak. Otrzymano także warunki, które wystarczają, aby uniknąć nadmiernej stabilności.

6

Thermosolutal instability of Walters' rotating fluid (Model B') in porous medium

Sharma R., Sunil, Chand S.

Archives of Mechanics

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1999

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Vol. 51, nr 2

181-191

EN

The thermosolutal instability of Walters' (Model B') fluid in porous medium is considered in the presence of uniform vertical rotation. For the case of stationary convection, the stable solute gradient and rotation have stabilizing effects on the system, whereas the medium permeability has a destabilizing (or stabilizing) effect on the system under certain conditions. The dispersion relation is also analysed numerically. It has also been shown that as rotation parameter increases, the stabilizing range of medium also increases. The kinematic viscoelasticity has no effect on the stationary convection. The stable solute gradient, rotation, porosity and kinematic viscoelasticity introduce oscillatory modes in the system, which did not occur in their absence. The sufficient conditions for the non-existance of overstability are also obtained.

7

Thermosolutal convection in Rivlin-Ericksen fluid in porous medium in hydromagnetics

Sharma R. C., Sunil, Chand S.

Applied Mechanics and Engineering

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1998

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Vol. 3, no 1

171-180

EN

The thermosolutal convection in Rivlin-Ericksen fluid in porous medium is considered in the presence of uniform vertical magnetic field. For the case of stationary convection, the stable solute gradient and magnetic field have stabilizing effects on the system, whereas, the medium permeability has destabilizing effect on the system. The kinematic viscoelasticity has no effect on stationary convection. The stable solute gradient and magnetic field introduce oscillatory modes in the system, which were non-existent in their absence. The sufficient conditions for the non-existence of overstability are also obtained.