425 research outputs found
OPERATIONAL TESTS OF EBWR VAPOR RECOVERY SYSTEM
A description of the Experimental Boiling Water Reactor vapor-recovery system is given. The seal air operating pressures, temperatures, and moisture content were measured. Air flow through the seals was measured and seal wear was assessed. Assuming direct-cycle D/sub 2/ operation, the seals were evaluated relative to the amount of D/sub 2/ leakage that would be controlled (C.J.G.
Guide to the geology of Garden of the Gods area, Gallatin, Hardin, Pope, and Saline counties, Illinois
"April 14, 2001, May 12, 2001" - cover.Includes bibliographical references (p. 75-76)
Noncommutativity and Lorentz Violation in Relativistic Heavy Ion Collisions
The experimental detection of the effects of noncommuting coordinates in
electrodynamic phenomena depends on the magnitude of |\theta B|, where \theta
is the noncommutativity parameter and B a background magnetic field. With the
present upper bound on \theta, given by \theta_{\rm bound} \simeq 1/(10 {\rm
TeV})^2, there was no large enough magnetic field in nature, including those
observed in magnetars, that could give visible effects or, conversely, that
could be used to further improve \theta_{\rm bound}. On the other hand,
recently it has been proposed that intense enough magnetic fields should be
produced at the beginning of relativistic heavy ion collisions. We discuss here
lepton pair production by free photons as one kind of signature of
noncommutativity and Lorentz violation that could occur at RHIC or LHC. This
allows us to obtain a more stringent bound on \theta, given by 10^{-3}
\theta_{\rm bound}, if such "exotic" events do not occur.Comment: Five pages, no figures
Availability of the Colchester coal for mining in northern and western Illinois
Includes bibliographical references (p. 17-19).This report is the fourth in a series to assess the availability of coal resources for future mining in Illinois.Coal resource classification system. -- Sources of data, limitations and mapping procedures. -- Geology and mining: Colchester coal: floor and roof stratigraphy. -- Coal quality. -- Quadrangle studies
Classical aspects of Hawking radiation verified in analogue gravity experiment
There is an analogy between the propagation of fields on a curved spacetime
and shallow water waves in an open channel flow. By placing a streamlined
obstacle into an open channel flow we create a region of high velocity over the
obstacle that can include wave horizons. Long (shallow water) waves propagating
upstream towards this region are blocked and converted into short (deep water)
waves. This is the analogue of the stimulated Hawking emission by a white hole
(the time inverse of a black hole). The measurements of amplitudes of the
converted waves demonstrate that they appear in pairs and are classically
correlated; the spectra of the conversion process is described by a
Boltzmann-distribution; and the Boltzmann-distribution is determined by the
determined by the change in flow across the white hole horizon.Comment: 17 pages, 10 figures; draft of a chapter submitted to the proceedings
of the IX'th SIGRAV graduate school: Analogue Gravity, Lake Como, Italy, May
201
TeV Astrophysics Constraints on Planck Scale Lorentz Violation
We analyze observational constraints from TeV astrophysics on Lorentz
violating nonlinear dispersion for photons and electrons without assuming any a
priori equality between the photon and electron parameters. The constraints
arise from thresholds for vacuum Cerenkov radiation, photon decay and
photo-production of electron-positron pairs. We show that the parameter plane
for cubic momentum terms in the dispersion relations is constrained to an order
unity region in Planck units. We find that the threshold configuration can
occur with an asymmetric distribution of momentum for pair creation, and with a
hard photon for vacuum Cerenkov radiation.Comment: 4 pages, RevTeX4, 1 figure. Some references and a footnote added,
improved discussion on the photon annihilation and GZK cutoff. Minor changes
of wording. Main results unchanged. Version to appear as a Rapid
Communication in PR
Phenomenological description of quantum gravity inspired modified classical electrodynamics
We discuss a large class of phenomenological models incorporating quantum
gravity motivated corrections to electrodynamics. The framework is that of
electrodynamics in a birefringent and dispersive medium with non-local
constitutive relations, which are considered up to second order in the inverse
of the energy characterizing the quantum gravity scale. The energy-momentum
tensor, Green functions and frequency dependent refraction indices are
obtained, leading to departures from standard physics. The effective character
of the theory is also emphasized by introducing a frequency cutoff. The
analysis of its effects upon the standard notion of causality is performed,
showing that in the radiation regime the expected corrections get further
suppressed by highly oscillating terms, thus forbiding causality violations to
show up in the corresponding observational effects.Comment: 14 pages, to be published in Obregon Festschrift 2006, Gen. Rel. and
Gra
Noncommutative Self-dual Gravity
Starting from a self-dual formulation of gravity, we obtain a noncommutative
theory of pure Einstein theory in four dimensions. In order to do that, we use
Seiberg-Witten map. It is shown that the noncommutative torsion constraint is
solved by the vanishing of commutative torsion. Finally, the noncommutative
corrections to the action are computed up to second order.Comment: 15+1 pages, LaTeX, no figure
A synthesis of carbon dioxide emissions from fossil-fuel combustion
This synthesis discusses the emissions of carbon dioxide from fossil-fuel combustion and cement production. While much is known about these emissions, there is still much that is unknown about the details surrounding these emissions. This synthesis explores our knowledge of these emissions in terms of why there is concern about them; how they are calculated; the major global efforts on inventorying them; their global, regional, and national totals at different spatial and temporal scales; how they are distributed on global grids (i.e., maps); how they are transported in models; and the uncertainties associated with these different aspects of the emissions. The magnitude of emissions from the combustion of fossil fuels has been almost continuously increasing with time since fossil fuels were first used by humans. Despite events in some nations specifically designed to reduce emissions, or which have had emissions reduction as a byproduct of other events, global total emissions continue their general increase with time. Global total fossil-fuel carbon dioxide emissions are known to within 10 % uncertainty (95 % confidence interval). Uncertainty on individual national total fossil-fuel carbon dioxide emissions range from a few percent to more than 50 %. This manuscript concludes that carbon dioxide emissions from fossil-fuel combustion continue to increase with time and that while much is known about the overall characteristics of these emissions, much is still to be learned about the detailed characteristics of these emissions
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