1,634 research outputs found
Study of pressure losses in tubing and fittings Final report, Jun. 1, 1964 - Jun. 1, 1966
Steady state and transient fluid flow equations for predicting friction and pressure in tubing and fitting systems - computer progra
Study of pressure losses in tubing and fittings Quarterly progress report, Dec. 1965 - Feb. 1966
Pressure losses in tubing and fittings - flow systems analysis, entrance effects in flexible metal hoses, and methods for analyzing flow over rough surfac
Vibration effects on heat transfer in cryogenic systems Quarterly progress report, Jul. 1 - Sep. 30, 1967
Water test apparatus used to determine vibration effects on heat transfer in cryogenic system
Vibration effects on heat transfer in cryogenic systems Quarterly progress report no. 1, Jun. 1 - Aug. 31, 1966
Vibration effects on natural convection and fluid transport properties in cryogenic system
LOFAR observations of radio burst source sizes and scattering in the solar corona
Low frequency radio wave scattering and refraction can have a dramatic effect
on the observed size and position of radio sources in the solar corona. The
scattering and refraction is thought to be due to fluctuations in electron
density caused by turbulence. Hence, determining the true radio source size can
provide information on the turbulence in coronal plasma. However, the lack of
high spatial resolution radio interferometric observations at low frequencies,
such as with the LOw Frequency ARray (LOFAR), has made it difficult to
determine the true radio source size and level of radio wave scattering. Here
we directly fit the visibilities of a LOFAR observation of a Type IIIb radio
burst with an elliptical Gaussian to determine its source size and position.
This circumvents the need to image the source and then de-convolve LOFAR's
point spread function, which can introduce spurious effects to the source size
and shape. For a burst at 34.76 MHz, we find full width at half maximum (FWHM)
heights along the major and minor axes to be and
, respectively, at a plane of sky heliocentric
distance of 1.75 R. Our results suggest that the level of density
fluctuations in the solar corona is the main cause of the scattering of radio
waves, resulting in large source sizes. However, the magnitude of
may be smaller than what has been previously derived in observations of radio
wave scattering in tied-array images.Comment: 6 pages, 3 figures, accepted for publication in Astronomy &
Astrophysic
Observations of Low Frequency Solar Radio Bursts from the Rosse Solar-Terrestrial Observatory
The Rosse Solar-Terrestrial Observatory (RSTO; www.rosseobservatory.ie) was
established at Birr Castle, Co. Offaly, Ireland (53 05'38.9", 7 55'12.7") in
2010 to study solar radio bursts and the response of the Earth's ionosphere and
geomagnetic field. To date, three Compound Astronomical Low-cost Low-frequency
Instrument for Spectroscopy and Transportable Observatory (CALLISTO)
spectrometers have been installed, with the capability of observing in the
frequency range 10-870 MHz. The receivers are fed simultaneously by biconical
and log-periodic antennas. Nominally, frequency spectra in the range 10-400 MHz
are obtained with 4 sweeps per second over 600 channels. Here, we describe the
RSTO solar radio spectrometer set-up, and present dynamic spectra of a sample
of Type II, III and IV radio bursts. In particular, we describe fine-scale
structure observed in Type II bursts, including band splitting and rapidly
varying herringbone features
Tracking a beam of electrons from the low solar corona into interplanetary space with the Low Frequency Array, Parker Solar Probe and 1 au spacecraft
Type III radio bursts are the result of plasma emission from mildly
relativistic electron beams propagating from the low solar corona into the
heliosphere where they can eventually be detected in situ if they align with
the location of a heliospheric spacecraft. Here we observe a type III radio
burst from 0.1-16 MHz using the Parker Solar Probe (PSP) FIELDS Radio Frequency
Spectrometer (RFS), and from 10-80 MHz using the Low Frequency Array (LOFAR).
This event was not associated with any detectable flare activity but was part
of an ongoing noise storm that occurred during PSP encounter 2. A deprojection
of the LOFAR radio sources into 3D space shows that the type III radio burst
sources were located on open magnetic field from 1.6-3 and originated
from a specific active region near the East limb. Combining PSP/RFS
observations with WIND/WAVES and Solar Terrestrial Relations Observatory
(STEREO)/WAVES, we reconstruct the type III radio source trajectory in the
heliosphere interior to PSP's position, assuming ecliptic confinement. An
energetic electron enhancement is subsequently detected in situ at the STEREO-A
spacecraft at compatible times although the onset and duration suggests the
individual burst contributes a subset of the enhancement. This work shows
relatively small-scale flux emergence in the corona can cause the injection of
electron beams from the low corona into the heliosphere, without needing a
strong solar flare. The complementary nature of combined ground and space-based
radio observations, especially in the era of PSP, is also clearly highlighted
by this study.Comment: 17 pages, 10 figures, Submitted to ApJ, April 15 202
The global precipitation response to volcanic eruptions in the CMIP5 models
We examine the precipitation response to volcanic eruptions in the Coupled Model Intercomparison Project Phase 5 (CMIP5) historical simulations compared to three observational datasets, including one with ocean coverage. Global precipitation decreases significantly following eruptions in CMIP5 models, with the largest decrease in wet tropical regions. This also occurs in observational land data, and ocean data in the boreal cold season. Monsoon rainfall decreases following eruptions in both models and observations. In response to individual eruptions, the ITCZ shifts away from the hemisphere with the greater concentration of aerosols in CMIP5. Models undergo a longer-lasting ocean precipitation response than over land, but the response in the short satellite record is too noisy to confirm this. We detect the influence of volcanism on precipitation in all three datasets in the cold season, although the models underestimate the size of the response. In the warm season the volcanic influence is only marginally detectable
Mind the gap? The persistence of pathological discourses in urban regeneration policy
Urban regeneration policy has historically framed policy problems using a discourse that pathologises areas and spatial communities. Since 2001 in England, and 2002 in Scotland a structural change in policy has occurred where citywide partnerships are now meant overcome structural spatial inequalities, countering pathological explanations. This paper uses historical and discourse analysis to evaluate one of the major community regeneration strategies developed by the Scottish Executive in 2002: Better Communities in Scotland: Closing the Gap. It seeks to ask whether structural change in policy was paralleled by discursive change; what discursive path dependence is evidenced? The text is placed in the historic context of UK urban renewal policies dating back to the launch of the Urban Programme in 1968 and particularly the policy discourse created by the influential Conservative government policy of 1988 New Life for Urban Scotland and the wider discourses of poverty and neighbourhood renewal policy created by Labour governments since 1997. The close textual analysis of the text shows that Better Communities in Scotland continues to pathologise spatial communities. Although this suggests a degree of historical path dependency, the historic breadth of the analysis also problematises simple historical determinism
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