It was known that a mesh screen placed across an airflow will have an evening effect, distributing both the velocity and pressure across the screen, however this effect had not been quantified and the effect of different mesh geometries was unknown. It was desired to understand the relationship between airflow velocity, the pressure behind the screen and the free hole area of the screen. It was...

We formulate conditions on the geometry of a non-expanding horizon ∆ which are sufficient for the space-time metric to coincide on ∆ with the Kerr metric. We introduce an invariant which can be used as a measure of how different the geometry of a given non-expanding horizon is from the geometry of the Kerr horizon. Directly, our results concern the space-time metric at ∆ at the zeroth and the f...

It is argued that under natural hypothesis the Fermions inside a black hole formed after the collapse of a neutron star could form a non compressible fluid (well before reaching the Planck scale) leading to some features of integer Quantum Hall Effect. The relations with black hole entropy are analyzed. Insights coming from Quantum Hall Effect are used to analyze the coupling with Einstein equa...

The effect of pressure on acceptor levels and hole scattering mechanisms in p-GaSe is investigated through Hall effect and resistivity measurements under quasi-hydrostatic conditions up to 4 GPa. The pressure dependence of the hole concentration is interpreted through a carrier statistics equation with a single (nitrogen) or double (tin) acceptor whose ionization energies decrease under pressur...

We present a new approach for setting initial Cauchy data for multiple black hole spacetimes. The method is based upon adopting an initially Kerr-Schild form of the metric. In the case of non-spinning holes, the constraint equations take a simple hierarchical form which is amenable to direct numerical integration. The feasibility of this approach is demonstrated by solving analytically the prob...

Recently, it has been shown that the wave equation for a scalar field on the exterior part of the Schwarzschild manifold satisfies local decay estimates useful for scattering theory and global existence [2]. The extension for the linearized Einstein equation is considered here. In 1957, Regge and Wheeler investigated spin 2 tensor fields on the Schwarzschild manifold [4]. They classified such f...

We present a pseudo-Newtonian potential for accretion disk modeling around rotating black holes. This potential can describe the general relativistic effects in accretion disk properly. As the inclusion of rotation in a proper way is very important at the inner edge of the disk we derived our potential starting from the Kerr metric. This potential can reproduce all the essential properties of g...

We use the Bergmann energy-momentum complex to calculate the energy of a charged regular black hole. The energy distribution is the same as we obtained in the Einstein prescription. Also, we get the expression of the energy in the Bergmann prescription for a general spherically symmetric space-time of the Kerr-Schild class.

We compare the results of constructing binary black hole initial data with three different decompositions of the constraint equations of general relativity. For each decomposition we compute the initial data using a superposition of two Kerr-Schild black holes to fix the freely specifiable data. We find that these initial-data sets differ significantly, with the ADM energy varying by as much as...

In this paper we show that the vanishing of the scalar curvature of Ruppeiner-like metrics does not characterize the ideal gas. Furthermore, we claim through an example that flatness is not a sufficient condition to establish the absence of interactions in the underlying microscopic model of a thermodynamic system, which poses a limitation on the usefulness of Ruppeiner’s metric and conjecture....