91,136 research outputs found
FELIX A full acceptance detector at the LHC
The FELIX collaboration has proposed the construction of a full acceptance
detector for the LHC, to be located at Intersection Region 4, and to be
commissioned concurrently with the LHC. The primary mission of FELIX is QCD: to
provide comprehensive and definitive observations of a very broad range of
strong-interaction processes. This paper reviews the detector concept and
performance characteristics, the physics menu, and plans for integration of
FELIX into the collider lattice and physical environment. The current status of
the FELIX Letter of Intent is discussed.Comment: 11 pages, 7 figures. To be published in "Proceedings of the XXVII
International Symposium on Multiparticle Dynamics, Frascati (Rome), Italy
8-12 Sept. 1997 (Nuclear Physics B, Proceedings Supplement)
The F-Word
I’m thinking of a word. Can you guess it? This word is considered negative and harsh. It’s generally avoided in everyday conversations. You wouldn’t normally hear this word spoken by professors or sophisticated celebrities. It starts with an F… Do you know it?
That’s right folks! It’s “feminist”. [excerpt
Outflow boundary conditions for 3D simulations of non-periodic blood flow and pressure fields in deformable arteries
The simulation of blood flow and pressure in arteries requires outflow
boundary conditions that incorporate models of downstream domains. We
previously described a coupled multidomain method to couple analytical models
of the downstream domains with 3D numerical models of the upstream vasculature.
This prior work either included pure resistance boundary conditions or
impedance boundary conditions based on assumed periodicity of the solution.
However, flow and pressure in arteries are not necessarily periodic in time due
to heart rate variability, respiration, complex transitional flow or acute
physiological changes. We present herein an approach for prescribing lumped
parameter outflow boundary conditions that accommodate transient phenomena. We
have applied this method to compute haemodynamic quantities in different
physiologically relevant cardiovascular models, including patient-specific
examples, to study non-periodic flow phenomena often observed in normal
subjects and in patients with acquired or congenital cardiovascular disease.
The relevance of using boundary conditions that accommodate transient phenomena
compared with boundary conditions that assume periodicity of the solution is
discussed
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Impact pressures generated by spherical particle hypervelocity impact on Yorkshire Sandstone
Hypervelocity impact tests were carried out at 4.8 km/s using the Open University's All Axis Light Gas Gun (AALGG) in the Planetary and Space Sciences Research Institute (PSSRI)'s Hypervelocity Impact Laboratory. A first estimate of the peak loading pressures was made using preliminary hydrocode simulations, supported by calculations. Following a review of existing published quartz and sandstone data, our previously published plate impact data were combined with high pressure quartz data to produce a synthetic Hugoniot. This will form the basis of future hydrocode modelling, as a linear Us-Up relationship does not adequately represent the behaviour of sandstone over the pressure range of interest, as indicated by experimental data on Coconino sandstone. This work is a precursor to investigating the biological effects of shock on microorganisms in sandstone targets. This paper also contains the first presentation of results of ultra high speed imaging of hypervelocity impact at the Open University. © 2007 American Institute of Physics
Finite Element Flow Simulations of the EUROLIFT DLR-F11 High Lift Configuration
This paper presents flow simulation results of the EUROLIFT DLR-F11
multi-element wing configuration, obtained with a highly scalable finite
element solver, PHASTA. This work was accomplished as a part of the 2nd high
lift prediction workshop. In-house meshes were constructed with increasing mesh
density for analysis. A solution adaptive approach was used as an alternative
and its effectiveness was studied by comparing its results with the ones
obtained with other meshes. Comparisons between the numerical solution obtained
with unsteady RANS turbulence model and available experimental results are
provided for verification and discussion. Based on the observations, future
direction for adaptive research and simulations with higher fidelity turbulence
models is outlined.Comment: 52nd Aerospace Sciences Meetin
Weak lensing with COMBO-17: estimation and removal of intrinsic alignments
We estimate and remove the contamination of weak gravitational lensing
measurements by the intrinsic alignment of close pairs of galaxies. We do this
by investigating both the aperture mass B mode statistic, and the shear
correlations of close and distant pairs of galaxies. We re-analyse the COMBO-17
survey, and study published results from the RCS and the VIRMOS-DESCART survey,
concluding that the intrinsic alignment effect is at the lower end of the range
of theoretical predictions. We also revisit this theoretical issue, and show
that misalignment of baryon and halo angular momenta may be an important effect
which can reduce the intrinsic ellipticity correlations estimated from
numerical simulations to the level that we and the SuperCOSMOS survey observe.
We re-examine the cosmological parameter estimation from the COMBO-17 survey,
now marginalising over the Hubble constant. Assuming no evolution in galaxy
clustering, and marginalising over the intrinsic alignment signal, we find the
mass clustering amplitude is reduced by 0.03 to sigma_8(Omega_m / 0.27)^0.6 =
0.71 +/- 0.11. We consider the forthcoming SNAP wide weak lensing survey, and
the CFHTLS wide synoptic survey, and expect them to be contaminated on scales
>1 arcmin by intrinsic alignments at the level of ~1% and ~2% respectively.
Division of the SNAP survey for lensing tomography significantly increases the
contamination in the lowest redshift bin to ~7% and possibly higher. Removal of
the intrinsic alignment effect by the downweighting of nearby galaxy pairs will
therefore be vital for SNAP, (abridged).Comment: Accepted for publication in MNRAS, 15 pages, 18 figure
Simultaneous Spin-Charge Relaxation in Double Quantum Dots
We investigate phonon-induced spin and charge relaxation mediated by
spin-orbit and hyperfine interactions for a single electron confined within a
double quantum dot. A simple toy model incorporating both direct decay to the
ground state of the double dot and indirect decay via an intermediate excited
state yields an electron spin relaxation rate that varies non-monotonically
with the detuning between the dots. We confirm this model with experiments
performed on a GaAs double dot, demonstrating that the relaxation rate exhibits
the expected detuning dependence and can be electrically tuned over several
orders of magnitude. Our analysis suggests that spin-orbit mediated relaxation
via phonons serves as the dominant mechanism through which the double-dot
electron spin-flip rate varies with detuning.Comment: 5 pages, 3 figures, Supplemental Material (2 pages, 2 figures
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