A theoretical study of the build-up of the Sun's polar magnetic field by using a 3D kinematic dynamo model

We develop a three-dimensional kinematic self-sustaining model of the solar dynamo in which the poloidal field generation is from tilted bipolar sunspot pairs placed on the solar surface above regions of strong toroidal field by using the SpotMaker algorithm, and then the transport of this poloidal field to the tachocline is primarily caused by turbulent diffusion. We obtain a dipolar solution within a certain range of parameters. We use this model to study the build-up of the polar magnetic field and show that some insights obtained from surface flux transport (SFT) models have to be revised. We present results obtained by putting a single bipolar sunspot pair in a hemisphere and two symmetrical sunspot pairs in two hemispheres.We find that the polar fields produced by them disappear due to the upward advection of poloidal flux at low latitudes, which emerges as oppositely-signed radial flux and which is then advected poleward by the meridional flow. We also study the effect that a large sunspot pair, violating Hale's polarity law would have on the polar field. We find that there would be some effect---especially if the anti-Hale pair appears at high latitudes in the mid-phase of the cycle---though the effect is not very dramatic.Comment: 18 pages, 18 figures, published in Ap

A microangiographic study of the effect of hyperthermia on the rabbit bladder

A model was used to study the effect of hyperthermia on a normal tissue. The model selected was the rabbit bladder and the end point measured was the changes in the micro-vasculature of the bladder wall. It was already demonstrated clinically that hot water bladder infusions produce regression in bladder tumors

High Temperature Carbonization of Coal

It is defined as heating the coal in absence of air to a final solid mass temperature of 900 degree Centigrade and above. It is the only method of producing hard coke from coking coal with better size consistency, hardness and richer in fixed carbon content to cater the needs of the blast furnace, foundry, and chemical industry

AC conductivity of unconventional bismuth cuprate glass

The frequency dependence of the AC electrical conductivity of different compositions of bismuth cuprate glasses has been presented in the temperature range 80 - 400 K. The conductivity data have been analysed in terms of different theoretical models to determine the possible conduction mechanism. Analysis of the conductivity data and the frequency exponent shows that the correlated barrier hopping of electrons between Cu+ and Cu3+ ions in the glasses is the most favourable mechanism for AC conduction. The different parameters obtained from the fits of this model to the experimental data are reasonable. The high value of the dielectric constant observed in this glass system can be attributed to the influence of the high polarizability of the Bi3+ions of the unconventional network former Bi2O3 on the AC response

Ac relaxation mechanism in some cuprate glasses

Electrical conductivity and dielectric properties of some unconventional lead cuprate glasses have been reported in the temperature range of 80-550 K and in the frequency range 102 -106 Hz. The experimental data have been analyzed in the light of different theoretical models. It has been observed that at low temperatures, the ac conductivity is much higher than the dc conductivity and the hopping of electrons between localized states near the Fermi level is the dominant loss mechanism. At higher temperatures, the ac conductivity approaches the dc conductivity and the dipolar relaxation model with a distribution of relaxation times can give the best description of the experimental data. Dipolar relaxation occurs due to the hopping of charge carriers within a range of energies near the mobility edge. The conductivity relaxation model provides satisfactory values of low- and high-frequency dielectric constants and dc conductivity. On the other hand, the random-free-energy-barrier model is not consistent with the dielectric data. The unconventional glass network former PbO gives rise to large values of the low- and high-frequency dielectric constants and a narrower distribution of relaxation times than the conventional network formers

Transport properties of nonconventional lead cuprate glass

The dc electrical transport properties of the nonconventional lead cuprate glasses of compositions (CuO)x(PbO)100-x for x=15-50 mol% are reported in the temperature range 150-500 K. The experimental results have been analyzed in the light of existing theoretical models. It has been observed that the high-temperature conductivity data are consistent with Mott's nearest-neighbor hopping model, while at low temperatures Mott's variable-range-hopping model fits the data very well. The polaron hopping models of Schnakenberg and Emin can predict the conductivity data in the entire temperature range of measurement. The percolation model of Triberis and Friedman is not consistent with the experimental results