52,324 research outputs found
Long duct nacelle aerodynamic development for DC-10 derivatives
The results are presented of a wind tunnel test utilizing a 4.7-percent-scale semispan model of the DC-10 in the Calspan 8-foot transonic wind tunnel. The effect of a revised long-duct nacelle shape on the channel velocities, the incremental drag relative to the baseline long-duct nacelle, and channel velocities for the baseline long-duct nacelle were determined and compared with data obtained at Ames. The baseline and the revised long-duct nacelles are representative of a CF6-50 mixed-flow configuration and were evaluated on a model of a proposed DC-10 stretched-fuselage configuration. The results showed that the revised long-duct nacelle has an appreciable effect on the inboard channel velocities, resulting in an increased channel Mach number. However, the pressure recovery on the nacelle afterbody was about the same for both nacelles. The lift curves for both long-duct nacelle configurations were the same. The channel pressures measured at Calspan were in good agreement with those measured at Ames for the baseline long-duct nacelle. The incremental drag for the revised nacelle was measured as two to four counts (three counts is approximately equal to one percent of the airplane drag) higher than that of the baseline long-duct nacelle
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Effects of aerosols on the observed irradiance from the ultraviolet to near-infrared at the surface of Mars
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Radiative transfer modelling for the NOMAD-UVIS instrument on the ExoMars Trace Gas Orbiter mission
The NOMAD (Nadir and Occultation for MArs Discovery) instrument is a 3-channel (2 IR, 1 UV/Vis) spectrometer due to fly on the 2016 ExoMars Trace Gas Orbiter mission. A radiative transfer model for Mars has been developed providing synthetic spectra to simulate observations of the UVIS channel in both solar occultation and nadir viewing geometries. This will allow for the characterization and mitigation of the influence of dust on retrievals of ozone abundance
Symptomatic adrenal insufficiency during inhaled corticosteroid treatment
Symptomatic adrenal insufficiency, presenting
as hypoglycaemia or poor weight
gain, may occur on withdrawal of corticosteroid
treatment but has not previously
been reported during inhaled corticosteroid
treatment. This case series illustrates
the occurence of clinically
significant adrenal insufficiency in asthmatic
children while patients were on
inhaled corticosteroid treatment and the
unexpected modes of presentation. General
practitioners and paediatricians need
to be aware that this unusual but acute
serious complication may occur in patients
treated
The H1 Forward Track Detector at HERA II
In order to maintain efficient tracking in the forward region of H1 after the
luminosity upgrade of the HERA machine, the H1 Forward Track Detector was also
upgraded. While much of the original software and techniques used for the HERA
I phase could be reused, the software for pattern recognition was completely
rewritten. This, along with several other improvements in hit finding and
high-level track reconstruction, are described in detail together with a
summary of the performance of the detector.Comment: Minor revision requested by journal (JINST) edito
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The circulatory impact of dust from dust profile assimilation
We present results from a reanalysis of temperatures, dust columns and dust vertical profiles focussing on the assimilation, distribution and transport of dust in the martian atmosphere. The assimilation of dust vertical information in particular is a valuable technique which has been shown to be of vital importance to a successful assimilation of the martian atmosphere, with the vertical representation of the dust distribution having a critical effect on assimilation results generally.
Atmospheric dust is a key driver of the martian circulation. Dust-induced heating and cooling is a potential feedback mechanism for dust lifting, for example, and can modify the circulation to either enhance or suppress dust storm activity. Accurately representing its complex spatial and temporal distribution is therefore crucial for understanding Mars’ atmospheric dynamics and transport
The Circumstellar Structure and Excitation Effects around the Massive Protostar Cepheus A HW 2
We report SMA 335 GHz continuum observations with angular resolution of
~0.''3, together with VLA ammonia observations with ~1'' resolution toward Cep
A HW 2. We find that the flattened disk structure of the dust emission observed
by Patel et al. is preserved at the 0.''3 scale, showing an elongated structure
of ~$0.''6 size (450 AU) peaking on HW 2. In addition, two ammonia cores are
observed, one associated with a hot-core previously reported, and an elongated
core with a double peak separated by ~1.''3 and with signs of heating at the
inner edges of the gas facing HW 2. The double-peaked ammonia structure, as
well as the double-peaked CH3CN structure reported previously (and proposed to
be two independent hot-cores), surround both the dust emission as well as the
double-peaked SO2 disk structure found by Jimenez-Serra et al. All these
results argue against the interpretation of the elongated dust-gas structure as
due to a chance-superposition of different cores; instead, they imply that it
is physically related to the central massive object within a disk-protostar-jet
system.Comment: 12 pages, 3 figures; accepted for publication in the Astrophysical
Journa
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Martian atmospheric O<sub>3</sub> retrieval development for the NOMAD-UVIS spectrometer
The composition of atmospheric trace gases and aerosols is a highly variable and poorly constrained component of the martian atmosphere, and by affecting martian climate and UV surface dose, represents a key parameter in the assessment of suitability for martian habitability. The ExoMars Trace Gas Orbiter (TGO) carries the Open University (OU) designed Ultraviolet and VIsible Spectrometer (UVIS) instrument as part of the Belgian-led Nadir and Occultation for MArs Discovery (NOMAD) spectrometer suite. NOMAD will begin transmitting science observations of martian surface and atmosphere back-scattered UltraViolet (UV) and visible radiation in Spring 2018, which will be processed to derive spatially and temporally averaged atmospheric trace gas and aerosol concentrations, intended to provide a better understanding of martian atmospheric photo-chemistry and dynamics, and will also improve models of martian atmospheric chemistry, climate and habitability. Work presented here illustrates initial development and testing of the OU’s new retrieval algorithm for determining O3 and aerosol concentrations from the UVIS instrument
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