23,089 research outputs found
Experimental comparison of icing cloud instruments
Icing cloud instruments were tested in the spray cloud Icing Research Tunnel (IRT) in order to determine their relative accuracy and their limitations over a broad range of conditions. It was found that the average of the readings from each of the liquid water content (LWC) instruments tested agreed closely with each other and with the IRT calibration; but all have a data scatter (+ or - one standard deviation) of about + or - 20 percent. The effect of this + or - 20 percent uncertainty is probably acceptable in aero-penalty and deicer experiments. Existing laser spectrometers proved to be too inaccurate for LWC measurements. The error due to water runoff was the same for all ice accretion LWC instruments. Any given laser spectrometer proved to be highly repeatable in its indications of volume median drop size (DVM), LWC and drop size distribution. However, there was a significant disagreement between different spectrometers of the same model, even after careful standard calibration and data analysis. The scatter about the mean of the DVM data from five Axial Scattering Spectrometer Probes was + or - 20 percent (+ or - one standard deviation) and the average was 20 percent higher than the old IRT calibration. The + or - 20 percent uncertainty in DVM can cause an unacceptable variation in the drag coefficient of an airfoil with ice; however, the variation in a deicer performance test may be acceptable
Effects of heat input rates on T-1 and T-1A steel welds
Technology of T-1 and T-1A steels is emphasized in investigation of their weld-fabrication. Welding heat input rate, production weldment circumstances, and standards of welding control are considered
Mesoscopic dynamical differences from quantum state preparation in a Bose-Hubbard trimer
Conventional wisdom is that quantum effects will tend to disappear as the
number of quanta in a system increases, and the evolution of a system will
become closer to that described by mean field classical equations. In this
letter we combine newly developed experimental techniques to propose and
analyse an experiment using a Bose-Hubbard trimer where the opposite is the
case. We find that differences in the preparation of a centrally evacuated
trimer can lead to readily observable differences in the subsequent dynamics
which increase with system size. Importantly, these differences can be detected
by the simple measurements of atomic number.Comment: 5 pages, 4 figures, theor
Asymmetric Gaussian steering: when Alice and Bob disagree
Asymmetric steering is an effect whereby an inseparable bipartite system can
be found to be described by either quantum mechanics or local hidden variable
theories depending on which one of Alice or Bob makes the required
measurements. We show that, even with an inseparable bipartite system,
situations can arise where Gaussian measurements on one half are not sufficient
to answer the fundamental question of which theory gives an adequate
description and the whole system must be considered. This phenomenon is
possible because of an asymmetry in the definition of the original
Einstein-Podolsky-Rosen paradox and in this article we show theoretically that
it may be demonstrated, at least in the case where Alice and Bob can only make
Gaussian measurements, using the intracavity nonlinear coupler.Comment: 5 Pages, 4 Figure
Flap noise measurements for STOL configurations using external upper surface blowing
Screening tests of upper surface blowing on externally blown flaps configurations were conducted. Noise and turning effectiveness data were obtained with small-scale, engine-over-the-wing models. One large model was tested to determine scale effects. Nozzle types included circular, slot, D-shaped, and multilobed. Tests were made with and without flow attachment devices. For STOL applications the particular multilobed mixer and the D-shaped nozzles tested were found to offer little or no noise advantage over the round convergent nozzle. High aspect ratio slot nozzles provided the quietest configurations. In general, upper surface blowing was quieter than lower surface blowing for equivalent EBF models
Transient excitation and data processing techniques employing the fast fourier transform for aeroelastic testing
The development of testing techniques useful in airplane ground resonance testing, wind tunnel aeroelastic model testing, and airplane flight flutter testing is presented. Included is the consideration of impulsive excitation, steady-state sinusoidal excitation, and random and pseudorandom excitation. Reasons for the selection of fast sine sweeps for transient excitation are given. The use of the fast fourier transform dynamic analyzer (HP-5451B) is presented, together with a curve fitting data process in the Laplace domain to experimentally evaluate values of generalized mass, model frequencies, dampings, and mode shapes. The effects of poor signal to noise ratios due to turbulence creating data variance are discussed. Data manipulation techniques used to overcome variance problems are also included. The experience is described that was gained by using these techniques since the early stages of the SST program. Data measured during 747 flight flutter tests, and SST, YC-14, and 727 empennage flutter model tests are included
Generating controllable atom-light entanglement with a Raman atom laser system
We introduce a scheme for creating continuous variable entanglement between
an atomic beam and an optical field, by using squeezed light to outcouple atoms
from a BEC via a Raman transition. We model the full multimode dynamics of the
atom laser beam and the squeezed optical field, and show that with appropriate
two-photon detuning and two-photon Rabi frequency, the transmitted light is
entangled in amplitude and phase with the outcoupled atom laser beam. The
degree of entanglement is controllable via changes in the two-photon Rabi
frequency of the outcoupling process.Comment: 4 pages, 4 figure
NASA's climate data system primer, version 1.2
This is a beginner's manual for NASA's Climate Data System (NCDS), an interactive scientific information management system that allows one to locate, access, manipulate, and display climate-research data. Additional information on the use of the system is available from the system itself
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