4,946 research outputs found
Canonical Quantization of Spherically Symmetric Dust Collapse
Full text linkQuantum gravity effects are likely to play a crucial role in determining the
outcome of gravitational collapse during its final stages. In this contribution
we will outline a canonical quantization of the LeMaitre-Tolman-Bondi models,
which describe the collapse of spherical, inhomogeneous, non-rotating dust.
Although there are many models of gravitational collapse, this particular class
of models stands out for its simplicity and the fact that both black holes and
naked singularity end states may be realized on the classical level, depending
on the initial conditions. We will obtain the appropriate Wheeler-DeWitt
equation and then solve it exactly, after regularization on a spatial lattice.
The solutions describe Hawking radiation and provide an elegant microcanonical
description of black hole entropy, but they raise other questions, most
importantly concerning the nature of gravity's fundamental degrees of freedom.Comment: 19 pages no figures. Contribution to a festschrift in honor of Joshua
N. Goldber
Wind tunnel study of coal dust release from train wagons
Get PDFThe paper presents a wind tunnel study to assess the coal dust released due to aeolian erosion from wagons equipped with two different shelter cover systems. A 1:25 scale model was used, and it comprises one locomotive and four train wagons with a 3.55 m maximum length. Several tests were conducted for different train configurations, and two initial load levels, with an undisturbed flow velocity of 13.4 m/s.http://www.sciencedirect.com/science/article/B6V3M-4C7DFX4-2/1/7e5214aa39411c25551eb15955a969a
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