43,847 research outputs found
Transonic flutter and gust-response tests and analyses of a wind-tunnel model of a torsion free wing airplane
An exploratory study of a 1/5.5 size, complete airplane version of a torsion free wing (TFW) fighter aircraft was conducted. The TFW consisted of a wing/boom/canard assembly on each fuselage side that was interconnected by a common pivot shaft so that the TFW could rotate freely in pitch. The effect of the TFW was evaluated by comparing data obtained with the TFW free and the TFW locked to the fuselage. With the model mounted on cables to simulate an airplane free flying condition, flutter boundaries were measured at Mach number (M) from 0.85 to 1.0 and gust responses at M = 0.65 and 0.90. The critical flutter mode for the TFW free configuration was found experimentally to occur at M = 0.95 and had the rigid TFW pitch mode as its apparent aerodynamic driver
Laser-actuated mechanical device
Actuator is portable and can be used in high-temperature (over 500 C) environments by incorporating tungsten metal film and quartz window. Actuator can be triggered when it is not directly in laser beam path by utilizing fiber optics. It is advantageous for remotely switching ultra-high voltage systems
Optically actuated two position mechanical mover
An optically actuated mechanical mover adapted to be moved from an ambient position to an active position, is disclosed. The mechanical mover essentially comprises a piston/cylinder arrangement including a piston that is contained within an internal cylindrical chamber of a housing. The cylindrical chamber is configured to permit the piston to be moved for the length of the chamber as a work stroke. A lock pin extending through the piston, and diametrically opposed walls of the chamber housing, retain the piston in the ambient position at one end of the chamber. An actuator for producing a pressure or shock wave that drives the piston is positioned at the end of the chamber corresponding to the piston ambient position
A piezo-bar pressure probe
Piezo-bar pressure type probe measures the impact velocity or pressure of a moving debris cloud. It measures pressures up to 200,000 psi and peak pressures may be recorded with a total pulse duration between 5 and 65 musec
On the calculation of supersonic, separating, and reattaching flows
A method is developed for solving the laminar and turbulent compressible boundary-layer equations for separating and reattaching flows. Results of this method are compared with experimental data for two laminar and three turbulent boundary-layer, shock-wave interactions. Several Navier-Stokes solutions were obtained for each of the laminar boundary-layer, shock-wave interactions considered. Comparison of these solutions indicates a first-order sensitivity in C sub f to the computational mesh selected in both the viscous and inviscid portions of the flow
Fifteen-foot diameter modular space station Kennedy Space Center launch site support definition (space station program Phase B extension definition)
This document defines the facilities, equipment, and operational plans required to support the MSS Program at KSC. Included is an analysis of KSC operations, a definition of flow plans, facility utilization and modifications, test plans and concepts, activation, and tradeoff studies. Existing GSE and facilities that have a potential utilization are identified, and new items are defined where possible. The study concludes that the existing facilities are suitable for use in the space station program without major modification from the Saturn-Apollo configuration
Galaxies into the Dark Ages
We consider the capabilities of current and future large facilities operating
at 2\,mm to 3\,mm wavelength to detect and image the [CII] 158\,m line
from galaxies into the cosmic "dark ages" ( to 20). The [CII] line
may prove to be a powerful tool in determining spectroscopic redshifts, and
galaxy dynamics, for the first galaxies. We emphasize that the nature, and even
existence, of such extreme redshift galaxies, remains at the frontier of open
questions in galaxy formation. In 40\,hr, ALMA has the sensitivity to detect
the integrated [CII] line emission from a moderate metallicity, active
star-forming galaxy [; star formation rate (SFR) =
5\,\,yr], at at a significance of 6. The
next-generation Very Large Array (ngVLA) will detect the integrated [CII] line
emission from a Milky-Way like star formation rate galaxy (, SFR = 1\,\,yr), at at a significance
of 6. Imaging simulations show that the ngVLA can determine rotation
dynamics for active star-forming galaxies at , if they exist. Based
on our very limited knowledge of the extreme redshift Universe, we calculate
the count rate in blind, volumetric surveys for [CII] emission at
to 20. The detection rates in blind surveys will be slow (of order unity per
40\,hr pointing). However, the observations are well suited to commensal
searches. We compare [CII] with the [OIII] 88m line, and other ancillary
information in high galaxies that would aid these studies.Comment: 11pages, 8 figures, Accepted for the Astrophysical Journa
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Free healthy breakfasts in primary schools: A cluster randomised controlled trial of a policy intervention in Wales, UK
Objective: The present study evaluated the impact of a national school programme of universal free healthy breakfast provision in Wales, UK.
Design: A cluster randomised controlled trial with repeated cross-sectional design and a 12-month follow-up. Primary outcomes were breakfast skipping, breakfast diet and episodic memory. Secondary outcomes were frequency of eating breakfast at home and at school, breakfast attitudes, rest-of-day diet and class behaviour.
Setting: Primary schools in nine local education authority areas.
Subjects: A total of 4350 students (aged 9–11 years) at baseline and 4472 at follow-up in 111 schools.
Results: Students in intervention schools reported significantly higher numbers of healthy food items consumed at breakfast and more positive attitudes towards breakfast eating at 12 months. Parents in intervention schools reported significantly higher rates of consumption of breakfast at school and correspondingly lower rates of breakfast consumption at home. No other significant differences were found.
Conclusions: The intervention did not reduce breakfast skipping; rather, pupils substituted breakfast at home for breakfast at school. However, there were improvements in children’s nutritional intake at breakfast time, if not the rest of the day, and more positive attitudes to breakfast, which may have implications for life-course dietary behaviours. There was no impact on episodic memory or classroom behaviour, which may require targeting breakfast skippers
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