8,683 research outputs found
Wetting on Lines and Lattices of Cylinders
This paper discusses wetting and capillary condensation transitions on a line
and a rectangular array of cylinders using an interface potential formalism.
For a line of cylinders, there is a capillary condensation transition followed
by complete wetting if the cylinders are sufficiently close together. Both
transitions disappear as the cylinder separation is increased. The dependence
of the wetting phase diagram of a rectangular array of cylinders is discussed
as a function of the chemical potential, substrate--fluid interaction strength
and surface tension.Comment: 17 pages in total: 11 pages of Latex document and 6 pages of figures,
Latex Version 2.09, OUTP-93-40
Performance of a 1.15-pressure-ratio axial-flow fan stage with a blade tip solidity of 0.5
The overall and blade-element performance of a low-solidity, low-pressure-ratio, low-tip-speed fan stage is presented over the stable operating range at rotative speeds from 90 to 120 percent of design speed. At design speed a stage peak efficiency of 0.836 was obtained at a weight flow of 30.27 kilograms per second and a pressure ratio of 1.111. The pressure ratio was less than design pressure ratio, and the design energy input into the rotor was not achieved. A mismatch of the rotor and stator blade elements resulted due to the lower than design pressure ratio of the rotor
Chiral Symmetry Breaking and the Dirac Spectrum at Nonzero Chemical Potential
The relation between the spectral density of the QCD Dirac operator at
nonzero baryon chemical potential and the chiral condensate is investigated. We
use the analytical result for the eigenvalue density in the microscopic regime
which shows oscillations with a period that scales as 1/V and an amplitude that
diverges exponentially with the volume . We find that the discontinuity
of the chiral condensate is due to the whole oscillating region rather than to
an accumulation of eigenvalues at the origin. These results also extend beyond
the microscopic regime to chemical potentials .Comment: 4 pages, 1 figur
Atmospheric turbulence forecasting with a general circulation model for Cerro Paranal
In addition to astro-meteorological parameters, such as seeing, coherence time, and isoplanatic angle, the vertical profile of the Earth’s atmospheric turbulence strength and velocity is important for instrument design, performance validation and monitoring, and observation scheduling and management. Here we compare these astro-meteorological parameters as well as the vertical profile itself from a forecast model based on a general circulation model from the European Centre for Median range Weather Forecasts and the stereo-SCIDAR, a high-sensitivity turbulence profiling instrument in regular operation at Paranal, Chile. The model is fast to process as no spatial nesting or data manipulation is performed. This speed enables the model to be reactive based on the most up to date forecasts. We find that the model is statistically consistent with measurements from stereo-SCIDAR. The correlation of the median turbulence profile from the model and the measurement is 0.98. We also find that the distributions of astro-meteorological parameters are consistent. We compare contemporaneous measurements and show that the free atmosphere seeing, isoplanatic angle, and coherence time have correlation values of 0.64, 0.40, and 0.63, respectively. We show and compare the profile sequences from a large number of trial nights. We see that the model is able to forecast the evolution of dominating features. In addition to smart scheduling, ensuring that the most sensitive astronomical observations are scheduled for the optimum time, this model could enable remote site characterization using a large archive of weather forecasts and could be used to optimize the performance of wide-field adaptive optics system
An experimental investigation of the hypergolic ignition of some polymeric fuels with oxygen
Hypergolic ignition of polymeric fuels with oxyge
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