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1

Certain generalized q-operators

Prakash O., Sharma D., Maheshwari P.

Demonstratio Mathematica

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2015

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Vol. 48, nr 3

404--412

EN

The applications of q-calculus in the approximation theory is a very interesting area of research in the recent years, several new q-operators were introduced and their behaviour were discussed by many researchers. This paper is the extension of the paper [15], in which Durrmeyer type generalization of q-Baskakov–Stancu type operators were discussed by using the concept of q-integral operators. Here, we propose to study the Stancu variant of q-Baskakov–Stancu type operators. We establish an estimate for the rate of convergence in terms of modulus of continuity and weighted approximation properties of these operators.

2

Rate of convergence for certain mixed family of linear positive operators

Maheshwari P., Sharma D.

Journal of Mathematics and Applications

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2010

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Vol. 33

73-78

EN

The present paper deals with the mixed integrated operators Mn(f; x); which are linear and positive having different basis functions in summation and integration respectively. We estimate the rate of convergence for these operators for functions which have derivatives of bounded variation.

3

Thermal convection in a ferromagnetic fluid saturating a porous medium

Sunil, Bharti P.K., Sharma D.

Studia Geotechnica et Mechanica

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2007

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Vol. 29, nr 3-4

3-18

EN

This paper deals with the theoretical investigation of the thermal convection on a layer of ferromagnetic fluid heated from below saturating a porous medium subjected to a transverse uniform magnetic field. For a flat fluid layer contained between two free boundaries, an exact solution is obtained using a linear stability analysis theory and normal mode analysis method. In the case of stationary convection, the medium permeability and non-buoyancy magnetization both have a destabilizing effect on the system. The critical wave number and the critical magnetic thermal Rayleigh number for the on set of instability are also determined numerically for sufficiently large values of buoyancy magnetization parameter M1 and the results are depicted graphically. The principle of the exchange of stabilities is found to hold true for the ferromagnetic fluid heated from below saturating a porous medium.

PL

Teoretycznie badano konwekcję termiczną w warstwie cieczy ferromagnetycznej ogrzewanej od dołu i wysycającej ośrodek porowaty poddany działaniu poprzecznego, jednorodnego pola magnetycznego. Otrzymano dokładne rozwiązanie dla płaskiej warstwy cieczy zawartej między dwoma swobodnymi brzegami, wykorzystując teorię liniowej stateczności i metodę trybu zwykłego. W przypadku ustalonej konwekcji zarówno przepuszczalność ośrodka, jak i niepowietrzna magnetyzacja wpływają destabilizująco na układ. Krytyczna liczba falowa i krytyczna magnetyczno-termiczna liczba Rayleigha na początku utraty stabilności są wyznaczone numerycznie dla wystarczająco dużych wartości parametru powietrznej magnetyzacji, a otrzymane wyniki zostały przedstawione graficznie. Stwierdzono, że zasada wymiany stabilności może być stosowana do cieczy ferromagnetycznej ogrzewanej od spodu i wysycającej ośrodek porowaty.

4

The effect of rotation on thermosolutal convection in a ferromagnetic fluid

Sunil, Bharti P. K., Sharma D., Sharma R. C.

International Journal of Applied Mechanics and Engineering

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2005

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Vol. 10, no 4

713-730

EN

The effcct of rotation on the thermosolutal convection in a ferromagnetic fluid is analyzed for a fluid layer heated and soluted from below in the presence of a uniform magnetic field. Using the linearized stability theory and the normal mode analysis, an exact solution is obtained for the case of two free boundaries. For the case of stationary convection, non-buoyancy magnetization has a destabilizing effect on the system, whereas the stable solute gradient and rotation have a stabilizing effect on the system for lower vaIues of buoyancy magnetization M 1 . The critical magnetic thermal Rayleigh number for the onset of instabiIity is also determined numerically for large vaIues of buoyancy magnetization M 1 and results are depicted graphically. The principle of exchange of stabilities is found to hold true for the ferromagnetic fluid heated from below in the absence of a stabIe solute gradient and rotation. The oscillatory modes are introduced due to the presence of the stabIe solute gradient and rotation, which were non-existent in their absence. The sufficient conditions for the non-existence of overstability are also obtained.