13,903 research outputs found
Full potential solution of transonic quasi-3-D flow through a cascade using artificial compressability
The three-dimensional flow in a turbomachinery blade row was approximated by correcting for streamtube convergence and radius change in the throughflow direction. The method is a fully conservative solution of the full potential equation incorporating the finite volume technique on body fitted periodic mesh, with an artificial density imposed in the transonic region to insure stability and the capture of shock waves. Comparison of results for several supercritical blades shows good agreement with their hodograph solutions. Other calculations for these profiles as well as standard NACA blade sections indicate that this is a useful scheme analyzing both the design and off-design performance of turbomachinery blading
Pattern formation in self-propelled particles with density-dependent motility
We study the behaviour of interacting self-propelled particles, whose
self-propulsion speed decreases with their local density. By combining direct
simulations of the microscopic model with an analysis of the hydrodynamic
equations obtained by explicitly coarse graining the model, we show that
interactions lead generically to the formation of a host of patterns, including
moving clumps, active lanes and asters. This general mechanism could explain
many of the patterns seen in recent experiments and simulations
GRO J1744-28, search for the counterpart: infrared photometry and spectroscopy
Using VLT/ISAAC, we detected 2 candidate counterparts to the bursting pulsar
GRO J1744-28, one bright and one faint, within the X-ray error circles of
XMM-Newton and Chandra. In determining the spectral types of the counterparts
we applied 3 different extinction corrections; one for an all-sky value, one
for a Galactic Bulge value and one for a local value. We find the local value,
with an extinction law of alpha = 3.23 +- 0.01 is the only correction that
results in colours and magnitudes for both bright and faint counterparts
consistent with a small range of spectral types, and for the bright
counterpart, consistent with the spectroscopic identification. Photometry of
the faint candidate indicates it is a K7/M0 V star at a distance of 3.75 +- 1
kpc. This star would require a very low inclination angle (i < 9deg) to satisfy
the mass function constraints; however it cannot be excluded as the counterpart
without follow-up spectroscopy to detect emission signatures of accretion.
Photometry and spectroscopy of the bright candidate indicate it is most likely
a G/K III star. The spectrum does not show Br-gamma emission, a known indicator
of accretion. The bright star's magnitudes are in agreement with the
constraints placed on a probable counterpart by the calculations of Rappaport &
Joss (1997) for an evolved star that has had its envelope stripped. The mass
function indicates the counterpart should have M < 0.3 Msol for an inclination
of i >= 15deg; a stripped giant, or a main sequence M3+ V star are consistent
with this mass-function constraint. In both cases mass-transfer, if present,
will be by wind-accretion as the counterpart will not fill its Roche lobe given
the observed orbital period. The derived magnetic field of 2.4 x 10^{11} G will
inhibit accretion by the propeller effect, hence its quiescent state.Comment: 12 pages, 6 figures, 4 table, MNRAS accepted Changes to the content
and an increased analysis of the Galactic centre extinctio
Satellite voice broadcast. Volume 1: Executive summary
An Executive Summary of the Satellite Voice Broadcast System Study designs are synthesized for direct sound broadcast satellite systems for HF-, VHF-, and Ku-bands. Methods are developed and used to predict satellite weight, volume, and RF performance for the various concepts considered. Cost and schedule risk assessments are performed to predict time and cost required to implement selected concepts. Technology assessments and tradeoffs are made to identify critical enabling technologies that require development to bring technical risk to acceptable levels for full scale development
Anisotropy of permeability in faulted porous sandstones
Thank you to Total E & P UK for funding the project, and especially Chris Wibberley, Claude Gout and Stephane Vignau for input. The author would also like to thank Zoe Shipton and Graham Yielding for their constructive reviews of the manuscript. Thanks also to Manuel Prieto for sharing his MSc pilot study written at the University of Aberdeen, Professor Martin Lee and Peter Chung at the University of Glasgow for SEM use and lastly thank you to Gavin Tennent for access to the Clashach Quarry and for samples.Peer reviewedPublisher PD
Distributive Justice and the Crime Drop
Data were extracted from a total of almost 600000 respondents from all sweeps of the Crime Survey for England and Wales (CSEW) 1982-2012 to determine whether victimisation was more or less concentrated across households during the crime drop. The most victimised household decile experienced the greatest absolute decline in victimisation but still accounted for over 70% of all victimisations suffered. Methodological issues underlying the patterns observed are discussed. The characteristics associated with highly victimised household are consistent across survey sweeps. Cross-national and crime type extension of work of the kind undertaken is advocated as both intrinsically important and likely to clarify the dynamics of the crime drop
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