Effect of Prandtl Number on Linear Stability of Mixed Convective Flow in a Vertical Porous Annulus: A LTNE Approach

A comprehensive numerical study on linear stability of fully developed mixed convective flow in a vertical annulus filled with saturated porous medium is investigated. A local thermal non-equilibrium (LTNE) approach is considered. The flow is induced by external pressure gradient and buoyancy force. The non-Darcy Brinkman-Forchheimer extended model is considered. The governing equations are solved by spectral collocation method. Special attention is given to understand the effect of thermal non-equilibrium parameters: inter phase heat transfer coefficient (H) and porosity scaled thermal conductivity ratio (?) on instability boundary of basic flow in (Pr, Ra) -plane. Stability results indicate that for high permeable porous media depending on Prandtl number, the flow is least stable under either first azimuthal mode or zero azimuthal modes. The stability criteria of basic flow decreases on increasing the Prandtl number. Increasing of H stabilizes the basic flow, whereas, increasing of ? destabilizes it. Keywords: Porous media, mixed convection, linear stability, thermal non-equilibrium, non-Darcy model

INFORMATION VALUE IN WEED MANAGEMENT

Use of the economic threshold to improve the efficiency of preemergent-herbicide treatment decisions is limited by a lack of weed information. An economic model for assessing the expected value of weed information needed to implement a threshold decision rule is developed. Empirical results suggest that early season weed information can have value in cabbage weed management in Massachusetts.Crop Production/Industries,

A Study of Noon F2 Ionization in Relation to Geomagnetic Co-ordinates

The relation of F2 layer noon critical frequency with magnetic dip and geomagnetic latitude is studied for constant values of solar zenithal angle. The constant-x plots show two maxima situated on the two sides of the magnetic equator. An asymmetry between the northern and southern hemispheres is also revealed. For chosen values of solar zenith distance the ratio of noon fF2 at sunspot maximum to that at sunspot minimum is studied in relation to magnetic dip. The ratio is found to vary with magnetic dip displaying a minimum to the north of the magnetic equator

Shell model study of the pairing correlations

A systematic study of the pairing correlations as a function of temperature and angular momentum has been performed in the sd-shell region using the spherical shell model approach. The pairing correlations have been derived for even-even, even-odd and odd-odd systems near N=Z and also for the asymmetric case of N=Z+4. The results indicate that the pairing content and the behavior of pair correlations is similar in even-even and odd-mass nuclei. For odd-odd N=Z system, angular momentum I=0 state is an isospin, t=1 neutron-proton paired configuration. Further, these t=1 correlations are shown to be dramatically reduced for the asymmetric case of N=Z+4. The shell model results obtained are qualitatively explained within a simplified degenerate model

Small Quadrupole Deformation for the Dipole Bands in 112In

High spin states in $^{112}$In were investigated using $^{100}$Mo($^{16}$O, p3n) reaction at 80 MeV. The excited level have been observed up to 5.6 MeV excitation energy and spin $\sim$ 20$\hbar$ with the level scheme showing three dipole bands. The polarization and lifetime measurements were carried out for the dipole bands. Tilted axis cranking model calculations were performed for different quasi-particle configurations of this doubly odd nucleus. Comparison of the calculations of the model with the B(M1) transition strengths of the positive and negative parity bands firmly established their configurations.Comment: 10 pages, 11 figures, 2 table

Using coupled micropillar compression and micro-Laue diffraction to investigate deformation mechanisms in a complex metallic alloy Al13Co4

In this investigation, we have used in-situ micro-Laue diffraction combined with micropillar compression of focused ion beam milled Al13Co4 complex metallic alloy to study the evolution of deformation in Al13Co4. Streaking of the Laue spots showed that the onset of plastic flow occured at stresses as low as 0.8 GPa, although macroscopic yield only becomes apparent at 2 GPa. The measured misorientations, obtained from peak splitting, enabled the geometrically necessary dislocation density to be estimated as 1.1 x 1013 m-2