Einstein's field equations with variable gravitational and cosmological 'constants' are considered in the presence of bulk viscosity for a spatially flat homogeneous and isotropic universe. Solutions are obtained by using a 'gamma-law' equation of state p = (γ − 1)ρ, where the adiabatic parameter γ varies continuously as the universe expands. A unified description of the early evolution of universe is presented with a number of possible assumptions on the bulk viscous term and gravitational constant in which an inflationary phase is followed by radiation-dominated phase. We investigate the cosmological model with constant and time-dependent bulk viscosity (proportional to power function of energy density and to Hubble parameter) along with constant and variable gravitational constant. The effect of viscosity is shown to affect the past and future of the universe. In all cases, the cosmological constant is found to be positive and a decreasing function of time, which supports the results obtained from recent supernovae Ia observations. The possibility that the present acceleration of the universe is driven by a kind of viscous fluid is explained. At the background level this model is similar to the generalized Chaplygin gas model. The physical and geometrical significance of the early cosmological models has also been discussed.

A method to calculate transfer of heat in a reforming furnace has been developed. The total transfer of heat, from flames and flue gases, to a differential section of a reformer tube is considered simultaneous with the transfer of heat to the reacting gases and the reaction taking place inside it. Kinetic rate expressions describing steam-hydrocarbon reactions, under varying conditions of pressure, have been obtained by modifications in the available ones. These have been used in a mathematical model developed for simulation of side fired steamhydrocarbon reformers;. Agreement between plant data and simulation results is generally very good. The methods developed in this work could conveniently be used for design purposes.

Figure 2. Production cost, exclusive of feed cost, as a function of carrier cost for immobilized catalyst prepared from soluble isomerase having the indicated specific activities (SA), expressed as EU X mg-1 of protein, corresponding to the three isomerase preparations. III). Labor costs associated with purification, if they had been included, increase with the degree of purity, but this is counteracted by the decreasing labor costs associated with emptying and refilling the reactor.

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