18,357 research outputs found
Fluctuating pressures in flow fields of jets
The powered lift configurations under present development for STOL aircraft are the externally blown flap (EBF), involving direct jet impingement on the aircraft flaps, and the upper surface blown (USB), where the jet flow is attached on the upper surface of the wing and directed downwards. Towards the goal of developing scaling laws to predict unsteady loads imposed on the structural components of these STOL aircraft from small model tests, the near field fluctuating pressure behavior for the simplified cases of a round free cold jet and the same jet impinging on a flat plate was investigated. Examples are given of coherences, phase lags (giving convection velocities), and overall fluctuating pressure levels measured. The fluctuating pressure levels measured on the flat plate are compared to surface fluctuating pressure levels measured on full-scale powered-lift configuration models
Quality Risk and Profitability in Cattle Production: A Multivariate Approach
This study evaluates quality, production, and price risk within the context of overall profit variability in fed cattle production. The approach used offers a flexible way to estimate a large system of equations with more than three jointly related censored outcomes. Trade-offs between quality and yield grade levels and production measures, such as average daily gain and feeding efficiency, are evaluated. Simulation procedures are used to assess the impact of quality risk on overall profit variability. Results make an important contribution to existing research by explaining why price signals through grid quality grade premiums may not generate intended producer responses.censoring, copula, fed cattle, grid pricing, multivariate, quality risk, Livestock Production/Industries,
SEASAT: A satellite scatterometer illumination times of selected in situ sites
A list of times that the SEASAT A Satellite Scatterometer (SASS) illuminated from directly above or directly abeam, selected surface sites where in situ winds were measured is provided. The list is ordered by the Greenwich Mean Time (GMT) of the midpoint of the illumination period (hit time) for a given surface site. The site identification, the orbit number and the direction from the subtrack in which the truth lies are provided. The accuracy of these times depends in part upon the ascending node times, which are estimated to be within +.1 sec, and on the illumination time relative to the ascending node, which is estimated to be within +6 seconds. The uncertainties in the times provided were judged to be sufficiently small to allow efficient and accurate extraction of SASS and in situ data at the selected surface sites. The list contains approximately six thousand hit times from 61 geographically dispersed sites
Counter Rotating Open Rotor Animation using Particle Image Velocimetry
This article describes the two accompanying fluid dynamics videos for the
"Counter rotating open rotor flow field investigation using stereoscopic
Particle Image Velocimetry" presented at the 64th Annual Meeting of the APS
Division of Fluid Dynamics in Baltimore, Maryland, November 20-22, 2011.Comment: Videos are include
Appearance of the Single Gyroid Network Phase in Nuclear Pasta Matter
Nuclear matter under the conditions of a supernova explosion unfolds into a
rich variety of spatially structured phases, called nuclear pasta. We
investigate the role of periodic network-like structures with negatively curved
interfaces in nuclear pasta structures, by static and dynamic Hartree-Fock
simulations in periodic lattices. As the most prominent result, we identify for
the first time the {\it single gyroid} network structure of cubic chiral
symmetry, a well known configuration in nanostructured soft-matter
systems, both as a dynamical state and as a cooled static solution. Single
gyroid structures form spontaneously in the course of the dynamical
simulations. Most of them are isomeric states. The very small energy
differences to the ground state indicate its relevance for structures in
nuclear pasta.Comment: 7 pages, 4 figure
Intensity-dependent UV laser flash excitation of diphenylamine in methanol: A two-photon ionization mechanism involving the triplet state.
Cooperatively breeding cottontop tamarins (Saguinus oedipus) do not donate rewards to their long-term mates
This study tested the hypothesis that cooperative breeding facilitates the emergence of prosocial behavior by presenting cottontop tamarins (Saguinus oedipus) with the option to provide food rewards to pair-bonded mates. In Experiment 1, tamarins could provide rewards to mates at no additional cost while obtaining rewards for themselves. Contrary to the hypothesis, tamarins did not demonstrate a preference to donate rewards, behaving similar to chimpanzees in previous studies. In Experiment 2, the authors eliminated rewards for the donor for a stricter test of prosocial behavior, while reducing separation distress and food preoccupation. Again, the authors found no evidence for a donation preference. Furthermore, tamarins were significantly less likely to deliver rewards to mates when the mate displayed interest in the reward. The results of this study contrast with those recently reported for cooperatively breeding common marmosets, and indicate that prosocial preferences in a food donation task do not emerge in all cooperative breeders. In previous studies, cottontop tamarins have cooperated and reciprocated to obtain food rewards; the current findings sharpen understanding of the boundaries of cottontop tamarinsâ food-provisioning behavior
Artifacts with uneven sampling of red noise
The vast majority of sampling systems operate in a standard way: at each tick
of a fixed-frequency master clock a digitizer reads out a voltage that
corresponds to the value of some physical quantity and translates it into a bit
pattern that is either transmitted, stored, or processed right away. Thus
signal sampling at evenly spaced time intervals is the rule: however this is
not always the case, and uneven sampling is sometimes unavoidable.
While periodic or quasi-periodic uneven sampling of a deterministic signal
can reasonably be expected to produce artifacts, it is much less obvious that
the same happens with noise: here I show that this is indeed the case only for
long-memory noise processes, i.e., power-law noises with . The resulting artifacts are usually a nuisance although they can be
eliminated with a proper processing of the signal samples, but they could also
be turned to advantage and used to encode information.Comment: 5 figure
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