54,699 research outputs found
Static and Dynamic Pressure Distributions in a Short Labyrinth Seal
As part of a study into turbine blade tip destabilizing forces, a seals test rig was built in which spin rate, circular whirl rate, direction and amplitude of inlet swirl angle, and eccentricity can all be controlled over wide ranges, and measurements can be made at gap Reynolds numbers up to about 2 x 10(exp 4). This facility is described and preliminary data is presented for a one cavity labyrinth seal with a flat, stator mounted land. The impact of different flow coefficients for the first and second knives on the rotordynamic coefficients was found. While this effect is dominant for the direct forces, it should also be incorporated into calculations of cross forces where it has an impact under many conditions
Skywalking GEMS and UDF
The two large colour mosaics of the GEMS and UDF projects, both obtained with
the Hubble Space Telescope and ACS, consist of large amounts of data. We
present two web application pages (the GEMS and UDF "Skywalker") that allow to
pan around in these mosaics with downloading only small parts at a time.Comment: 1 pag
Seeing the sky through Hubble's eye: The COSMOS SkyWalker
Large, high-resolution space-based imaging surveys produce a volume of data
that is difficult to present to the public in a comprehensible way. While
megapixel-sized images can still be printed out or downloaded via the World
Wide Web, this is no longer feasible for images with 10^9 pixels (e.g., the
Hubble Space Telescope Advanced Camera for Surveys [ACS] images of the Galaxy
Evolution from Morphology and SEDs [GEMS] project) or even 10^10 pixels (for
the ACS Cosmic Evolution Survey [COSMOS]). We present a Web-based utility
called the COSMOS SkyWalker that allows viewing of the huge ACS image data set,
even through slow Internet connections. Using standard HTML and JavaScript, the
application successively loads only those portions of the image at a time that
are currently being viewed on the screen. The user can move within the image by
using the mouse or interacting with an overview image. Using an astrometrically
registered image for the COSMOS SkyWalker allows the display of calibrated
world coordinates for use in science. The SkyWalker "technique" can be applied
to other data sets. This requires some customization, notably the slicing up of
a data set into small (e.g., 256^2 pixel) subimages. An advantage of the
SkyWalker is the use of standard Web browser components; thus, it requires no
installation of any software and can therefore be viewed by anyone across many
operating systems.Comment: 4 pages, 2 figures, accepted for publication in PAS
Note on the space group selection rule for closed strings on orbifolds
It is well-known that the space group selection rule constrains the
interactions of closed strings on orbifolds. For some examples, this rule has
been described by an effective Abelian symmetry that combines with a
permutation symmetry to a non-Abelian flavor symmetry like or
. However, the general case of the effective Abelian symmetries was
not yet fully understood. In this work, we formalize the computation of the
Abelian symmetry that results from the space group selection rule by imposing
two conditions only: (i) well-defined discrete charges and (ii) their
conservation. The resulting symmetry, which we call the space group flavor
symmetry , is uniquely specified by the Abelianization of the space group.
For all Abelian orbifolds with supersymmetry we compute and
identify new cases, for example, where contains a dark
matter-parity with charges 0 and 1 for massless and massive strings,
respectively.Comment: 28 pages, 1 tabl
A-term inflation and the MSSM
The parameter space for A-term inflation is explored with . With p=6 and \lambda_p~1, the observed spectrum and
spectral tilt can be obtained with soft mass of order 10^2 GeV but not with a
much higher mass. The case p=3 requires \lambda_p~10^{-9} to 10^{-12}. The
ratio m/A requires fine-tuning, which may be justified on environmental
grounds. An extension of the MSSM to include non-renormalizable terms and/or
Dirac neutrino masses might support either A-term inflation or modular
inflation.Comment: 10 pages, 3 figures; Comments added, typos correcte
Scene-based imperceptible-visible watermarking for HDR video content
This paper presents the High Dynamic Range - Imperceptible Visible Watermarking for HDR video content (HDR-IVW-V) based on scene detection for robust copyright protection of HDR videos using a visually imperceptible watermarking methodology. HDR-IVW-V employs scene detection to reduce both computational complexity and undesired visual attention to watermarked regions. Visual imperceptibility is achieved by finding the region of a frame with the highest hiding capacities on which the Human Visual System (HVS) cannot recognize the embedded watermark. The embedded watermark remains visually imperceptible as long as the normal color calibration parameters are held. HDR-IVW-V is evaluated on PQ-encoded HDR video content successfully attaining visual imperceptibility, robustness to tone mapping operations and image quality preservation
Search for neutrino charged current coherent pion production at SciBooNE
SciBooNE is a neutrino experiment measuring the neutrino cross sections on
carbon in the one GeV region. We have performed a search for charged current
coherent pion production from muon neutrinos scattering on carbon, \nu_\mu 12^C
\to \mu 12^C \pi^+. No evidence for coherent pion production is observed. We
set 90% confidence level upper limits on the cross section ratio of charged
current coherent pion production to the total charged current cross section at
0.67\times 10^{-2} at mean neutrino energy 1.1 GeV and 1.36 \times 10^{-2} at
mean neutrino energy 2.2 GeV. The kinematic distributions of the final data
sample are also presented.Comment: 6 pages, 6 figures, Proceedings of the 6th International Workshop on
Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt09
Chemodynamical Simulations of Elliptical Galaxies
We review recent developments in the field of chemodynamical simulations of
elliptical galaxies, highlighting (in an admittedly biased fashion) the work
conducted with our cosmological N-body/SPH code GCD+. We have demonstrated
previously the recovery of several primary integrated early-type system scaling
relations (e.g. colour-magnitude relation, L_X-T_X-[Fe/H]_X) when employing a
phenomenological AGN heating scheme in conjunction with a self-consistent
treatment of star formation, supernovae feedback, radiative cooling, chemical
enrichment, and stellar/X-ray population synthesis. Here we emphasise
characteristics derived from the full spatial information contained within the
simulated dataset, including stellar and coronal morphologies, metallicity
distribution functions, and abundance gradients.Comment: to appear in the proceedings of Chemodynamics: from first stars to
local galaxies, Lyon, Franc
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