1,718 research outputs found
Propeller propulsion integration, phase 1
A bibliography was compiled of all readily available sources of propeller analytical and experimental studies conducted during the 1930 through 1960 period. A propeller test stand was developed for the measurement of thrust and torque characteristics of full scale general aviation propellers and installed in the LaRC 30 x 60 foot full scale wind tunnel. A tunnel entry was made during the January through February 1980 period. Several propellers were tested, but unforseen difficulties with the shaft thrust torque balance severely degraded the data quality
A catalogue of devices applicable to the measurement of boundary layers and wakes on flight vehicles
A literature search was conducted to assemble a catalog of devices and techniques which have possible application to boundary layer and wake measurements on flight vehicles. The indices used in the search were NACA, NASA STAR, IAA, USGRDR and Applied Science and Technology Index. The period covered was 1950 through 1970. The devices contained in the catalog were restricted to those that provided essentially direct measurement of velocities, pressures and shear stresses. Pertinent material was included in the catalog if it contained either an adequate description of a device and associated performance data or a presentation of applicable information on a particular measurement theory and/or technique. When available, illustrations showing the configuration of the device and test condition data were also included
VLA radio continuum observations of a new sample of high redshift radio galaxies
We present new deep multi-frequency radio-polarimetric images of a sample of
high redshift radio galaxies (HzRGs), having redshift between 1.7 and 4.1. The
radio data at 4.7 and 8.2 GHz were taken with the Very Large Array in the A
configuration and provide a highest angular resolution of 0.2''. Maps of total
intensity, radio spectral index, radio polarization and internal magnetic field
are presented for each source. The morphology of most objects is that of
standard FRII double radio sources, but several contain multiple hot-spots in
one or both lobes. Compared to similar samples of HzRGs previously imaged,
there is a higher fraction (29%) of compact steep spectrum sources (i.e.
sources with a projected linear size less than 20 kpc). Radio cores are
identified in about half of the sample and tend to have relatively steep
spectra (alpha < -1). Polarization is detected in all but 4 sources, with
typical polarization at 8.2 GHz of around 10-20%. The Faraday rotation can be
measured in most of the radio galaxies: the observed rotation measure (RM) of 8
radio sources exceeds 100 rad m^{-2} in at least one of the lobes, with large
gradients between the two lobes. We find no dependence of Faraday rotation with
other properties of the radio sources. If the origin of the Faraday rotation is
local to the sources, as we believe, then the intrinsic RM is more than a 1000
rad m^{-2}. Because low redshift radio galaxies residing at the center of
clusters usually show extreme RMs, we suggest that the high-z large RM sources
also lie in very dense environments. Finally, we find that the fraction of
powerful radio galaxies with extreme Faraday rotation increases with redshift,
as would be expected if their average environment tends to become denser with
decreasing cosmic epoch.Comment: Accepted for publication in A&A Supplemen
A Chandra study of X-ray sources in the field of the z=2.16 radio galaxy MRC 1138-262
We present results from a Chandra X-ray Observatory study of the field X-ray
source population in the vicinity of the radio galaxy MRC 1138-262. Many
serendipitous X-ray sources are detected in an area of 8'x8' around the radio
source and 90% are identified in our deep VLT images. The space density of such
sources is higher than expected on the basis of the statistics of ROSAT and
Chandra deep surveys. The most likely explanation is in terms of a
concentration of AGN associated with the protocluster at z=2.16 which was found
around the radio galaxy in previous studies. Two sources have a confirmed
spectroscopic redshift close to that of the radio galaxy, and for three more
sources other observations suggest that they are associated with the
protocluster. Four of these five X-ray sources form, together with the radio
galaxy, a filament in the plane of the sky. The direction of the filament is
similar to that of the radio source axis, the large scale distribution of the
other protocluster members, the 150 kpc-sized emission-line halo and the
extended X-ray emission associated with the radio galaxy.
The majority of optically identified X-ray sources in this field have
properties consistent with type I AGN, a few could be soft, low luminosity
galaxies, one is probably an obscured (type II) AGN and one is a star. These
statistics are consistent with the results of deep X-ray surveys.Comment: 8 pages, 2 figures, to appear in Astronomy and Astrophysic
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