14,133 research outputs found
Foil radiometer accessory improves measurements
The responsiveness of a foil radiometer is increased and its time constant is simultaneously decreased by isolating the foil in a controlled environment. Using an optical system, it is coupled to the media to be measured, and the resulting concentration of energy permits the thermocouple junction temperature to respond quickly
Analysis of the High-Altitude Cooling of the Ranger SGV-770 D-4 Engine in the Bell XP-77 Airplane
No abstract availabl
Statistics of the Energy Dissipation Rate and Local Enstrophy in Turbulent Channel Flow
Using high-resolution direct numerical simulations, the height and Reynolds
number dependence of higher-order statistics of the energy dissipation rate and
local enstrophy are examined in incompressible, fully-developed turbulent
channel flow. The statistics are studied over a range of wall distances,
spanning the viscous sublayer to the channel flow centerline, for friction
Reynolds numbers and . The high resolution of
the simulations allows dissipation and enstrophy moments up to fourth order to
be calculated. These moments show a dependence on wall distance, and Reynolds
number effects are observed at the edge of the logarithmic layer. Conditional
analyses based on locations of intense rotation are also carried out in order
to determine the contribution of vortical structures to the dissipation and
enstrophy moments. Our analysis shows that, for the simulation at the larger
Reynolds number, small-scale fluctuations of both dissipation and enstrophy
become relatively constant for .Comment: Accepted by Physica
Leptoquark patterns unifying neutrino masses, flavor anomalies, and the diphoton excess
Vector leptoquarks provide an elegant solution to a series of anomalies and
at the same time generate naturally light neutrino masses through their mixing
with the standard model Higgs boson. We present a simple Froggatt-Nielsen model
to accommodate the B physics anomalies and , neutrino masses, and
the GeV diphoton excess in one cohesive framework adding only two vector
leptoquarks and two singlet scalar fields to the standard model field content.Comment: 12 pages, 10 figures; final version published in PR
Higgs as an indication for flavor symmetry
Lepton flavor violating Higgs decays can arise in flavor symmetry models
where the Higgs sector is responsible for both the electroweak and the flavor
symmetry breaking. Here we advocate an three-Higgs-doublet model where
tightly constrained flavor changing neutral currents are suppressed by a
remnant symmetry. A small breaking of this symmetry can explain the
excess of Higgs decay final states with a topology
reported recently by CMS if the new neutral scalars are light. The model also
predicts sizable rates for lepton flavor violating Higgs decays in the
and channels because of the unifying flavor symmetry.Comment: 15+9 pages, 7 figures, updated for publication in PR
Geometry of intensive scalar dissipation events in turbulence
Maxima of the scalar dissipation rate in turbulence appear in form of sheets
and correspond to the potentially most intensive scalar mixing events. Their
cross-section extension determines a locally varying diffusion scale of the
mixing process and extends the classical Batchelor picture of one mean
diffusion scale. The distribution of the local diffusion scales is analysed for
different Reynolds and Schmidt numbers with a fast multiscale technique applied
to very high-resolution simulation data. The scales take always values across
the whole Batchelor range and beyond. Furthermore, their distribution is traced
back to the distribution of the contractive short-time Lyapunov exponent of the
flow.Comment: 4 pages, 5 Postscript figures (2 with reduced quality
Probe samples components of rocket engine exhaust
Water-cooled, cantilevered probe samples the exhaust plume of rocket engines to recover particles for examination. The probe withstands the stresses of a rocket exhaust plume environment for a sufficient period to obtain a useful sample of the exhaust components
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