25,058 research outputs found
Test results from a dynamic model dynaflex rotor
A one-fifth scale dynamic model of the Sikorsky Dynaflex rotor was tested in hover and in forward flight conditions in a wind tunnel. The Dynaflex rotor features an advanced composite structure which flexes to provide a constant speed universal joint action. Testing concentrated on confirming that the stability and dynamic response of the rotor were satisfactory. Lift conditions of up to .11 Ct/sigma and advance ratios as high as .46 were reached. Vibratory loads were compared to those of articulated rotors. The Dynaflex rotor concept appears to be a practical concept from the standpoint of dynamic response and stability
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Mental Health of Children and Young People in England, 2017: Trends and characteristics
This survey series provides England’s best source of data on trends in child mental health. Emotional, behavioural, hyperactivity, and other types of mental disorder were assessed in 5 to 15 year olds in 1999, 5 to 16 year olds in 2004, and 5 to 19 year olds in 2017.
One in eight (12.8%) 5 to 19 year olds had a mental disorder when assessed in 2017. Rates were similar in boys and girls. Data for 5 to 15 year olds show a slight upward trend over time in the prevalence of emotional disorders.Rates for behavioural, hyperactivity and other disorders have remained broadly stable
Small-noise analysis and symmetrization of implicit Monte Carlo samplers
Implicit samplers are algorithms for producing independent, weighted samples
from multi-variate probability distributions. These are often applied in
Bayesian data assimilation algorithms. We use Laplace asymptotic expansions to
analyze two implicit samplers in the small noise regime. Our analysis suggests
a symmetrization of the algo- rithms that leads to improved (implicit) sampling
schemes at a rel- atively small additional cost. Computational experiments
confirm the theory and show that symmetrization is effective for small noise
sampling problems
Hospital and Physician Capacity Update
Offers an alternative view of healthcare costs by examining trends in hospital capacity and healthcare labor across regions. Outlines how effective management of healthcare capacity would enable affordable quality care that meets patient needs and wants
Grazing-angle scattering of electromagnetic waves in gratings with varying mean parameters: grating eigenmodes
A highly unusual pattern of strong multiple resonances for bulk
electromagnetic waves is predicted and analysed numerically in thick periodic
holographic gratings in a slab with the mean permittivity that is larger than
that of the surrounding media. This pattern is shown to exist in the geometry
of grazing-angle scattering (GAS), that is when the scattered wave (+1
diffracted order) in the slab propagates almost parallel to the slab (grating)
boundaries. The predicted resonances are demonstrated to be unrelated to
resonant generation of the conventional guided modes of the slab. Their
physical explanation is associated with resonant generation of a completely new
type of eigenmodes in a thick slab with a periodic grating. These new slab
eigenmodes are generically related to the grating; they do not exist if the
grating amplitude is zero. The field structure of these eigenmodes and their
dependence on structural and wave parameters is analysed. The results are
extended to the case of GAS of guided modes in a slab with a periodic groove
array of small corrugation amplitude and small variations in the mean thickness
of the slab at the array boundaries.Comment: 16 pages, 6 figure
Pairing transition of nuclei at finite temperature
Pairing transition at finite temperature was investigated by the shell model
and BCS calculations. The definitive signature of pairing transition is
identified by a "transition temperature" estimated from a "thermal"
odd-even mass difference, while there is no sharp phase transition because of
the finiteness of nucleus. It is found that is in good agreement with
predictions of critical temperature in the BCS approximation, and the
pairing correlations almost vanish at two points of the transition temperature
. The BCS calculations show that the critical temperature
increases with increasing deformation.Comment: 12 pages, 6 figures, accepted for publication in Nuclear Physics
Evaluation of effectiveness of various devices for attenuation of trailing vortices based on model tests in a large towing basin
The effectiveness of various candidate aircraft-wing devices for attenuation of trailing vortices generated by large aircraft is evaluated on basis of results of experiments conducted with a 0.03-scale model of a Boeing 747 transport aircraft using a technique developed at the HYDRONAUTICS Ship Model Basin. Emphasis is on the effects produced by these devices in the far-field (up to 8 kilometers downstream of full-scale generating aircraft) where the unaltered vortex-wakes could still be hazardous to small following aircraft. The evaluation is based primarily on quantitative measurements of the respective vortex velocity distributions made by means of hot-film probe traverses in a transverse plane at selected stations downstream. The effects of these altered wakes on rolling moment induced on a small following aircraft are also studied using a modified lifting-surface theory with a synthesized Gates Learjet as a typical example. Lift and drag measurements concurrently obtained in the model tests are used to appraise the effects of each device investigated on the performance characteristics of the generating aircraft
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Eating powerful transgressions: (re)assessing the spaces and ethics of organic food in the UK
The measurement of rock deformability in bore holes on earth. Adaptability to a lunar exploration program
Dilatometers, bore hole jacks, and penetrometers, for measurement of rock deformability in bore holes on eart
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