Oscillating Flow of a Viscous Liquid in a Porous Rectangular Duct

The unsteady flow of viscous incompressible liquid in a long porous straight duct of rectangular cross-section, under the influence of periodic pressure gradient using the generalised momentum equation, has been studied. The finite cosine transforms have been employed to solve the problem. Expressions for velocity distribution, volume flowrate (flux) and drag in the duct have been derived. A few particular cases have been deduced. It is found that the classical Darcian effectis felt only in a core very near to the axis of the duct and the non-Darcian phenomenon is felt predominently, near the boundary of the duct. Itis also found that the velocity, volume flow rate (flux) and drag increase with the increase in frequency of oscillations of liquid. Whereas the porosity of the medium reduces both the velocity and flux and increases the drag

Labour Market Dynamics in RBC Models

This paper explores the ability of a large set of RBC type models to explain aggregate US data by examining how well the rst-order conditions (FOCs) from each model t the data. Typically, the residuals from the FOC for hours worked are large in magnitude (more volatile than total hours), very highly persistent, and stay away from zero for long periods of time. This pattern suggests that standard RBC models are unable to capture the dynamics in the joint behaviour of consumption, output and hours that exists in the US data. We show that models which generate dynamic terms in the FOC for hours worked are able to capture this feature of the data by exploring a RBC model augmented by learning by doing which has been shown to have such a dynamic FOC. The results are remarkable. The residuals from the hours FOC are much less volatile than total hours and display no persistence. Less conclusive results emerge from models with habit formation in preferences which also yield dynamic FOCs for the labour input. We conclude that an additional dynamic component in the FOCs is essential to better capture the dynamics in the data and future research using the RBC structure should explore models that deliver it.

Selective Microdetermination of Uranium Using Weisz Ring Oven Technique: Application to an Indirect Determination of Trace Amounts of Arsenic in Tobacco

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Phenomemology of a Realistic Accelerating Universe Using Tracker Fields

We present a realistic scenario of tracking of scalar fields with varying equation of state. The astrophysical constraints on the evolution of scalar fields in the physical universe are discussed. The nucleosynthesis and the galaxy formation constraints have been used to put limits on $\Omega_\phi$ and estimate $\epsilon$ during cosmic evolution. Interpolation techniques have been applied to estimate $\epsilon\simeq0.772$ at the present epoch. The epoch of transition from matter to quintessence dominated era and consequent onset of acceleration in cosmic expansion is calculated and taking the lower limit $\Omega_n^0 = 0.2$ as estimated from $SN_e I_a$ data, it is shown that the supernova observations beyond redshift $z=1$ would reveal deceleration in cosmic expansion.Comment: 10 pages, 4 figures, late

Parametrization of dark energy equation of state Revisited

A comparative study of various parametrizations of the dark energy equation of state is made. Astrophysical constraints from LSS, CMB and BBN are laid down to test the physical viability and cosmological compatibility of these parametrizations. A critical evaluation of the 4-index parametrizations reveals that Hannestad-M\"{o}rtsell as well as Lee parametrizations are simple and transparent in probing the evolution of the dark energy during the expansion history of the universe and they satisfy the LSS, CMB and BBN constraints on the dark energy density parameter for the best fit values.Comment: 11 page