1,371 research outputs found
Aerodynamic investigations of ventilated brake discs.
The heat dissipation and performance of a ventilated brake disc strongly depends
on the aerodynamic characteristics of the flow through the rotor passages. The
aim of this investigation was to provide an improved understanding of ventilated
brake rotor flow phenomena, with a view to improving heat dissipation, as well
as providing a measurement data set for validation of computational fluid
dynamics methods. The flow fields at the exit of four different brake rotor
geometries, rotated in free air, were measured using a five-hole pressure probe
and a hot-wire anemometry system. The principal measurements were taken using
two-component hot-wire techniques and were used to determine mean and unsteady
flow characteristics at the exit of the brake rotors. Using phase-locked data
processing, it was possible to reveal the spatial and temporal flow variation
within individual rotor passages. The effects of disc geometry and rotational
speed on the mean flow, passage turbulence intensity, and mass flow were
determined. The rotor exit jet and wake flow were clearly observed as
characterized by the passage geometry as well as definite regions of high and
low turbulence. The aerodynamic flow characteristics were found to be reasonably
independent of rotational speed but highly dependent upon rotor geometry
On the heating mix of ITER (invited paper)
This paper considers the heating mix of ITER for the two main scenarios. Presently, 73MWof absorbed power are foreseen in the mix 20/33/20 for ECH, NBI and ICH. Given a sufficient edge stability, Q = 10 the goal of scenario 2 can be reached with 40MW power irrespective of the heating method but depends sensitively inter alia on the H-mode pedestal temperature, the density profile shape and on the characteristics of impurity transport. ICH preferentially heats the ions and would contribute specifically with Q 0.5, and strong off-axis current drive (CD). The findings presented here are based on revised CD efficiencies γ for ECCD and a detailed benchmark of several CD codes. With ECCD alone, the goals of scenario 4 can hardly be reached. Efficient off-axisCDis only possible with NBI.With beams, inductive discharges with fni > 0.8 can be maintained for 3000 s. The conclusion of this study is that the present heating mix of ITER is appropriate. It provides the necessary actuators to induce in a flexible way the best possible scenarios. The development risks of NBI at 1MeV can be reduced by operation at 0.85MeV
Perceptual judgment and saccadic behavior in a spatial distortion with briefly presented stimuli.
When observers are asked to localize the peripheral position of a small probe
with respect to the mid-position of a spatially extended comparison stimulus,
they tend to judge the probe as being more peripheral than the mid-position of
the comparison stimulus. This relative mislocalization seems to emerge from
differences in absolute localization, that is the comparison stimulus is
localized more towards the fovea than the probe. The present study compared
saccadic behaviour and relative localization judgements in three experiments and
determined the quantitative relationship between both measures. The results
showed corresponding effects in localization errors and saccadic behaviour.
Moreover, it was possible to estimate the amount of the relative mislocalization
by means of the saccadic amplitude
The cross-entropy method for continuous multi-extremal optimization
In recent years, the cross-entropy method has been successfully applied to a wide range of discrete optimization tasks. In this paper we consider the cross-entropy method in the context of continuous optimization. We demonstrate the effectiveness of the cross-entropy method for solving difficult continuous multi-extremal optimization problems, including those with non-linear constraints
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The Antiproton-Nucleon Annihilation Process (AntiprotonCollaboration Experiment)
In the exposure to a 7 0 0-MeV/c negative particle beam, 35 antiproton stars have been found. Of these antiprotons, 21 annihilate in flight and three give large-angle scatters ( {Theta} > 15 , T{sub P-} > 50 Mev), while 14 annihilate at rest. From the interactions in flight we obtain the total c r o s s section for antiproton interactio
Structural Properties of Polyglutamine Aggregates Investigated via Molecular Dynamics Simulations
Polyglutamine (polyQ) beta-stranded aggregates constitute the hallmark of Huntington disease. The disease is fully penetrant when Q residues are more than 36-40 ("disease threshold"). Here, based on a molecular dynamics study on polyQ helical structures of different shapes and oligomeric states, we suggest that the stability of the aggregates increases with the number of monomers, while it is rather insensitive to the number of Qs in each monomer. However, the stability of the single monomer does depend on the number of side-chain intramolecular H-bonds, and therefore oil the number of Qs. If such number is lower than that of the disease threshold, the beta-stranded monomers are unstable and hence may aggregate with lower probability, consistently with experimental findings. Our results provide a possible interpretation of the apparent polyQ length dependent-toxicity, and they do not support the so-called "structural threshold hypothesis", which supposes a transition from random coil to a beta-sheet structure only above the disease threshold
Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set
We report a measurement of the bottom-strange meson mixing phase \beta_s
using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays
in which the quark-flavor content of the bottom-strange meson is identified at
production. This measurement uses the full data set of proton-antiproton
collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment
at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity.
We report confidence regions in the two-dimensional space of \beta_s and the
B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2,
-1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in
agreement with the standard model expectation. Assuming the standard model
value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +-
0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +-
0.009 (syst) ps, which are consistent and competitive with determinations by
other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012
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