On the estimation of the vertical distribution of radiogenic heat production in the crust

Summary. A differential-difference equation governing the distribution of radiogenic heat in the crust has been obtained. The solution of this equation gives the exponential model of the heat production distribution with the logarithmic decrement as determined in Singh & Negi.     

Some anisotropic spatially-homogeneous cosmological models with electromagnetic field

Considering Bianchi type-I metric, cosmological models of a perfect fluid with an electromagnetic field have been obtained, using a supplementary condition between the metric potentials. The four-current is either zero or space-like. The model has expanding and shearing but non-rotating fluid flow which is also geodetic. The requirement of positive conductivity imposes an additional restriction on the model. Various physical and mathematical properties of the model have been discussed.     

The geometry of magnetic fieldlines in magnetogeostrophic flows

It is proved that the only circulation preserving magnetogeostrophic flows whose current density is lamellar, and bears a constant on a current density vector have (1) a plane motion of constant current density (on which certain unsteady potential motions may be superposed) and (2) a particular circular helical motion.     

Statistical properties of accumulated values and their application in mining estimations

This paper presents results of some investigations on the statistical properties of accumulation of discrete as well as continuous values when a two-dimensional stationary random function is reduced to a one-dimensional function. Based on the results of these investigations, an indirect technique of estimating covariances or variograms of point support grade values is proposed. The efficiency of the technique, particularly in relation to the conventional procedure of covariance estimation, has been demonstrated by an actual case study of a pre-Cambrian high-grade iron ore deposit in eastern India.     

A class of new Bianchi I perfect fluid space-times

A procedure to generate new exact solutions to Einstein equations for perfect fluids is applied to LRS Bianchi type I line-element. Starting from some known solutions a class of new perfect fluid solutions of Bianchi type I are presented. The physical and kinematical properties of spatially homogeneous and anisotropic cosmological models are studied.     

A self-similar flow in Generalized Roche model with increasing energy

The self-similar flow of a gas, moving under the gravitational attraction of a central body of fixed mass behind a spherical shock wave driven out by a propelling contact surface into quiet solar wind region, is investigated. The total energy content between the inner expanding surface and the shock front increases with time. In the last section we briefly pose the self-similar isothermal flow of a gas behind a spherical shock wave.     

Flow behind an attached shock wave in a radiating gas

A simple method is used to determine the curvature of an attached shock wave and the flow variable gradients behind the shock curve at the tip of a straight-edged wedge placed symmetrically in a supersonic flow of a radiating gas near the optically thin limit. The shock curvature and the flow variable gradients along the wedge at the tip are computed for a wide range of upstream flow Mach numbers and wedge angles. Several interesting results are noted; in particular, it is found that the effect of an increase in the upstream flow Mach number or the radiative flux is to enhance the shock wave curvature which, however, decreases with an increase in the specific heat ratio or the wedge angle.     

Hall effects on heat and mass transfer flow through porous medium

Effects of Hall current on free convection and mass transfer flow through a porous medium bounded by a vertical surface has been analysed. The problem is solved analytically. The velocity profiles are shown on graphs. Effects ofm (Hall parameter).K ^* (permeability parameter), and Sc (Schmidt number) on velocity are discussed.     

Thermosolutal-convective instability in a stellar atmosphere

The thermosolutal-convective instability of a stellar atomsphere is studied in the presence of suspended particles. The criteria for monotonic instability are derived and are found to hold good also in the presence of uniform rotation and uniform magnetic field on the thermosolutal-convective instability. The thermosolutal-convective instability of a stellar atmosphere is also studied in the presence of suspended particles and radiative transfer effects and the criteria for monotonic instability are obtained in terms of source function.     

Use of Roche coordinates in the problems of small oscillations of tidally distorted stellar models

The system of Roche coordinates developed by Kopal to study the problems of stars in close binary systems has been used to study the problems of small oscillations of tidally distorted stars.