11,535 research outputs found
Wind turbine acoustic standards
A program is being conducted to develop noise standards for wind turbines which minimize annoyance and which can be used to design specifications. The approach consists of presenting wind turbine noise stimuli to test subjects in a laboratory listening chamber. The responses of the subjects are recorded for a range of stimuli which encompass the designs, operating conditions, and ambient noise levels of current and future installations. Results to date have established the threshold of detectability for a range of impulsive stimuli of the type associated with blade/tower wake interactions. The status of the ongoing psychoacoustic tests, the subjective data, and the approach to the development of acoustic criteria/standards are described
Investigation of slosh anomaly in Apollo lunar module propellant gage
Analysis of propellant sloshing in lunar module during Apollo 14 flight and resultant erroneous indication of low level of propellan
Ring baffle pressure distribution and slosh damping in large cylindrical tanks
An investigation was conducted to determine the pressure loads and damping associated with rigid ring baffles in relatively large cylindrical tanks. The radial and circumferential pressure distribution, as well as the damping, was measured on a ring baffle subjected to fundamental antisymmetric slosh in a 284-cm-diameter rigid tank. Experimental and analytical data are presented as a function of slosh velocity or amplitude, baffle spacing, and baffle locations both above and below the liquid surface. Results suggest that pressure distributions and damping values can be determined from available theories for the design of single and multiple baffle configurations
Discovery of a Binary Centaur
We have identified a binary companion to (42355) 2002 CR46 in our ongoing
deep survey using the Hubble Space Telescope's High Resolution Camera. It is
the first companion to be found around an object in a non-resonant orbit that
crosses the orbits of giant planets. Objects in orbits of this kind, the
Centaurs, have experienced repeated strong scattering with one or more giant
planets and therefore the survival of binaries in this transient population has
been in question. Monte Carlo simulations suggest, however, that binaries in
(42355) 2002 CR46 -like heliocentric orbits have a high probability of survival
for reasonable estimates of the binary's still-unknown system mass and
separation. Because Centaurs are thought to be precursors to short period
comets, the question of the existence of binary comets naturally arises; none
has yet been definitively identified. The discovery of one binary in a sample
of eight observed by HST suggests that binaries in this population may not be
uncommon.Comment: 20 pages, 4 figures, 1 table accepted for publication in Icaru
Guide to the evaluation of human exposure to noise from large wind turbines
Guidance for evaluating human exposure to wind turbine noise is provided and includes consideration of the source characteristics, the propagation to the receiver location, and the exposure of the receiver to the noise. The criteria for evaluation of human exposure are based on comparisons of the noise at the receiver location with the human perception thresholds for wind turbine noise and noise-induced building vibrations in the presence of background noise
Medical professionalism: more than fitness to practise
The General Medical Council (GMC) and the Medical Schools Council have produced guidance on professional behaviour for medical schools and students. The guidance focuses particularly on fitness to practise.While fitness to practise is vital for the protection of patients, we argue that it is only one aspect involved in the teaching and learning of professionalism
Recurrence interval analysis of high-frequency financial returns and its application to risk estimation
We investigate the probability distributions of the recurrence intervals
between consecutive 1-min returns above a positive threshold or
below a negative threshold of two indices and 20 individual stocks in
China's stock market. The distributions of recurrence intervals for positive
and negative thresholds are symmetric, and display power-law tails tested by
three goodness-of-fit measures including the Kolmogorov-Smirnov (KS) statistic,
the weighted KS statistic and the Cram\'er-von Mises criterion. Both long-term
and shot-term memory effects are observed in the recurrence intervals for
positive and negative thresholds . We further apply the recurrence interval
analysis to the risk estimation for the Chinese stock markets based on the
probability , Value-at-Risk (VaR) analysis and VaR analysis
conditioned on preceding recurrence intervals.Comment: 17 pages, 10 figures, 1 tabl
Metallicity of Red Giants in the Galactic Bulge from Near-Infrared Spectroscopy
We present K-band spectra of more than 110 M giants in Galactic bulge fields
interior to -4 degrees and as close as 0.2 degrees of the Galactic Center. From
the equivalent widths of three features in these spectra, EW(Na),EW(Ca), and
EW(CO) we calculate [Fe/H] for the stars with a calibration derived from
globular clusters Stephens et al (2000). The mean [Fe/H] for each field is in
good agreement with the results from Frogel et al. (1999) based on the slope of
the giant branch method. We find no evidence for a metallicity gradient along
the minor or major axes of the inner bulge (R < 0.6 kpc). A metallicity
gradient along the minor axis, found earlier, arises when fields located at
larger galactic radius are included. However, these more distant fields are
located outside of the infrared bulge defined by the COBE/DIRBE observations.
We compute the [Fe/H] distribution for the inner bulge and find a mean value of
-0.21 dex with a full width dispersion of 0.30 dex, close to the values found
for Baade's Window (BW) by Sadler et al. (1996) and to a theoretical prediction
for a bulge formed by dissipative collapse Molla et al (2000).Comment: 32 pages, 10 figures, AJ submitte
System for measuring passenger reaction to transportation-vehicle vibration
Equipment is capable of measuring frequencies from 0 to 50 Hz and is portable, light, inexpensive, and easily adaptable to field operations. System could be used in situations where it is necessary to record simultaneously subject response to other types of physical measurement or stimuli, such as temperature, noise, or pressure
- …