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1

Studies on the morphs, life history and behaviour of green apple aphid, Aphis pomi DE GEER on apple host in India

100%

Kumari M. , Gautam D. C.

Polish Journal of Entomology

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2007

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tom 76

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nr 2

EN

The morphs of green apple aphid occurring on apple host in Himachal Pradesh, which is the main apple growing state of India, were ascertained and their life history was studied on the apple nursery plants from 2002 to 2006 in Mashobra locality (3101'N latitude, 7701'E longitude and altitude 2286 m above sea level) of Shimla district and Ner Chowk locality (31032'N latitude, 76054'E longitude and altitude 878 m above sea level) of Mandi district of Himachal Pradesh. Only two kinds of parthenogenetic morphs i.e. apterous and alate parthenogenetic viviparous females occur in this state. Biological characteristics, life history and behaviour of these morphs were studied in different seasons Heavy infestations of green apple aphid prevent the terminal growth of the plants which show distorted growth. This aphid pest builds up big colonies on twigs, leaf petioles and the underside of the leaves. Its settling behaviour on apple plants allows accommodating large number of aphids in a small area on shoots and leaves. Maximum alate morphs were produced from May to August and number of alates was also more in crowded colonies. The alate aphids infest new plants and build up new colonies there. The populations of this insect pest increase in early May and reach high peaks in July. The effect of aphids’ feeding on the growth of nursery plants was also measured.

2

Free convection over a vertical rotating cone with constant wall heat flux

100%

Kumari M. , Pop I.

Applied Mechanics and Engineering

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1998

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tom Vol. 3, no 3

451-464

EN

This paper summarizes a numerical study of free convection flow over a vertical rotating cone in a quiescent fluid. A combined forced/free convection parameter is defined which allows the description of the entire regime from pure free convection to pure forced convection flow. The transformed equations are solved numerically for some values of the Prandtl number and the combined convection parameter using a very efficient finite-difference method. The effects of these parameters on the velocity and temperature fields as well as on the local skin friction and wall temperature distribution are illustrated. The results are compared with those from the literature. An excellent agreement is found.

3

Mixed convection along a vertical cone with uniform surface heat flux for fluids of any Prandtl number

80%

Kumari M. , Jaradat M. A. , Pop I.

International Journal of Applied Mechanics and Engineering

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2007

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tom Vol. 12, no 3

733-744

EN

An analysis of a steady laminar mixed convection boundary layer flow along a vertical cone of constant wall heat flux for any Prandtl number is presented. A mixed convection parameter [...], as proposed by Lin and Chen (1988), is used to serve as a controlling parameter that determines the relative importance of the forced and the free convection flows. New coordinates and dependent variabIes are then defined in terms of [...], so that the transformed non-similar boundary layer equations give computationally efficient numerical solutions which are valid over the entire range of the mixed convection flow from the forced convection limit [...] to the free convection limit [...] for fluids of any Prandtl number. The effect of the mixed convection parameter and the Prandtl number on the velocity and temperature profile s as well as on the skin friction and heat transfer coefficients are shown for both cases of buoyancy assisting and buoyancy opposing flow conditions, respectively.

4

Computational fluid dynamics modelling of buoyancy induced viscoelastic flow in a porous medium with magnetic field effects

80%

Beg O. A. , Takhar H. S. , Kumari M. , Nath G.

International Journal of Applied Mechanics and Engineering

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2001

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tom Vol. 6, no 1

187-210

EN

A 2-dimensional computational fluid dynamics analysis of steady state thermal boundary layer flow of a second order non-Newtonian fluid past a horizontal wedge in a Brinkman-Darcy porous medium, in the presence of a transverse magnetic field, is presented. The governing equations are transformed from Cartesian coordinates (x,y) into a sixth order system of partial differential equations in a 'ksi'-n coordinate system. These complex equations are then reduced to a set of six first order equations which are solved using the robust Keller finite difference method, and a block tridiagonal iterative solver, SOLV6. It is shown that heat transfer magnitude is depressed by magnetic field parameter (Hartmann number, Ha) and also considerably reduced with increasing viscoelasticity parameter (K). Surface shear stresses are also reported to fall considerably with increase in viscoelasticity of the fluid. Effects of other hydrodynamic and thermal parameters on the flow are discussed in detail.

5

Synthesis, Characterization and Reactivity of Niobium(V)-2-tert-butylphenoxides

80%

Sharma N. , Sharma M. , Kumari M. , Chaudhry S. C.

Polish Journal of Chemistry

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2009

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tom Vol. 83, nr 9

1565-1573

EN

The niobium(V)-2-butylphenoxides of composition [NbCl(OC6H4C(CH3)3-2)4] (I) and [Nb(OC6H4C(CH3)3-2)5] (II) have been synthesized by the reaction of NbCl5 with Me3SiOC6H4C(CH3)3-2 in CCl4 and have been characterized by elemental analyses, molar conductance, molecular weight determination, IR, 1H and 13C NMR and UV-VIS spectral studies. The molecular model calculations were performed to visualize the probable geometry acquired by the complexes. Based upon spectral and molecular modelling dynamics, a square-pyramidal geometry around niobium in complexes has been proposed. Thermal behaviour of the complexes has been studied by TG, DTA and DSC techniques. The reactions of [NbCl(OC6H4C(CH3)3-2)4] (I) with chloride ion accecptors – FeCl3 and PCl5 have yielded complexes of composition [Nb(OC6H4C(CH3)3-2)4]×[FeCl4] and [Nb(OC6H4C(CH3)3-2)4]×[PCl6] authenticated by physicochemical and IR data.

6

Synthesis, Characterization and Thermal Studies of Niobium(V) Complexes of 2-tert-Butylphenol

80%

Sharma N. , Sharma M. , Kumari M. , Chaudhry S. C.

Polish Journal of Chemistry

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2009

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tom Vol. 83, nr 7

1265-1276

EN

Complexes of composition [NbCl4(OC6H4C(CH3)3-2)] and [NbCl3(OC6H4C(CH3)3-2)2] have been synthesized from the reaction of niobium pentachloride with equimolar and bimolar amounts of 2-tert-butylphenol in carbon tetrachloride. The complexes have been characterized by physicochemical, IR, 1H and 13C NMR and UV-VIS spectral studies. Based upon these studies, for complexes mononuclear square-pyramidal geometry around niobium has been proposed. Thermal decompositional behaviour of the complexes has been studied by TG, DTA and DSC techniques. From TG data, the kinetic and thermodynamic parameters viz. energy of activation, frequency factor, order of reaction, entropy of activation etc. have been evaluated using Freeman-Carroll, Coats-Redfern and Horowitz-Metzger equations. The reactions of complexes with a variety of nitrogenous bases (L1–L5) (where L1 = imidazole, L2 = benzimidazole, L3 = N-methylimidazole, L4 = 2,2'-bipyridyl and L5 = 1,10-phenanthroline) yielded 1:1 addition compounds authenticated by analytical and IR spectral studies.

7

Boundary layers growth on a moving surface due to an impulsive motion and a sudden increase of wall heat flux

80%

Kumari M. , Grosan T. , Pop I.

International Journal of Applied Mechanics and Engineering

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2008

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tom Vol. 13, no 1

203-215

EN

In this paper we investigate the development of the momentum and thermal boundary layers over a continuous moving semi-infinite flat plate when the extemal stream starts impulsively from rest at time t = O with a constant velocity [...] It is assumed that the plate starts to supply heat to the fluid at a constant rate qw at time t = O and maintained at this rate. The problem has been formulated in a new system of scaled coordinates such that for [...] it reduces to Rayleigh type of equation and for [...] (large time) it reduces to Blasius or Sakiadis type of equation. A new scale of dimensionless time ? has been used which reduces the region of time integration from an infinite region [...] to a finite time region [...] which reduces the computational time considerably. The goveming partial differential equations are transformed into a singular parabolic partial differential equations which have been solved numerically for a range of values of the goveming parameters using an implicit finite-difference scheme. The results show that there is a smooth transition from Rayleigh solution to Blasius or Sakiadis solution as the dimensionless time [...] increases from zero to one.

8

Buoyancy effects in boundary layers on a continuously moving vertical surface with a parallel free stream

80%

Takhar H. S. , Kumari M. , Nath G.

Archives of Mechanics

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2001

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tom Vol. 53, nr 2

151-166

EN

An analysis is performed to study the effect of the buoyancy force on the flow and heat transfer characteristics in a viscous fluid over a heated vertical continuously moving surface with a parallel free stream. The buoyancy force varies with the streamwise distance ... and hence introduces nonsimilarity in the flow field. Both the constant wall temperature and constant heat flux conditions are included in the analysis. The partial differential equations governing the flow are solved numerically. Closed form solutions are obtained when the wall and free stream velocities are equal and there is no buoyancy force. Also the correlation equations for the local Nusselt number are developed. It is found that for opposing flow or for an upstream moving wall, the solution does not exist beyond a certain value of the buoyancy parameter or the ratio of wall and free stream velocities.

9

Synthesis, Characterization and Antibacterial Activity of Triorganotin(IV) Complexes of 4-Methylphenol

70%

Sharma N. , Kumar V. , Thakur M. , Kumari M. , Chaudhry S. C.

Polish Journal of Chemistry

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2009

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tom Vol. 83, nr 12

2051--2065

EN

The triorganotin(IV) com plex of com po si tion Ph3Sn(OArMe-4) has been synthesized in good yields by the reaction of Ph3SnCl with Me3SiOArMe-4/NaOArMe-4, while complexes of composition Me3Sn(OArMe-4) and n-Bu3Sn(OArMe-4) (where -OArMe-4 = -OC6H4CH3-4) have been obtained from the reaction of Me3SnCl and n-Bu3SnCl with 4-methylphenol in the presence of triethylamine in carbon tetrachloride. The complexes have been characterized by elemental analyses, molar conductance measurements, molecular weight determin tion and IR, 1H and 13C NMR and mass spectral studies. Thermal behaviour of the complexes has been studied by TG and DTA techniques. The organotin(IV) complexes have also been screened for their antibacterial properties and are found to exhibit appreciable activity. The reactions of the complexes with 2-, 3-, 4-cyanopyridines yielded 1:1 adducts as confirmed by physicochemical and IR spectral data.