15,456 research outputs found
Mechanical testing of advanced coating system, volume 1
The Electron Beam Physical Vapor Deposition (EBPVD) coating material has a highly columnar microstructure, and as a result it was expected to have very low tensile strength. To be able to fabricate the required compression and tensile specimens, a substrate was required to provide structural integrity for the specimens. Substrate and coating dimensions were adjusted to provide sufficient sensitivity to resolve the projected loads carried by the EBPVD coating. The use of two distinctively different strain transducer systems, for tension and compression loadings, mandated two vastly different specimen geometries. Compression specimen and tensile specimen geometries are given. Both compression and tensile test setups are described. Data reduction mathematical models are given and discussed in detail as is the interpretation of the results. Creep test data is also given and discussed
Fatigue testing of plasma-sprayed thermal barrier coatings, volume 2
A plasma sprayed thermal barrier coating for diesel engines were fatigue tested. Candidate thermal barrier coating materials were fatigue screened and a data base was generated for the selected candidate material. Specimen configurations are given for the bend fatigue tests, along with test setup, specimen preparation, test matrix and procedure, and data analysis
Semiclassical model for calculating fully differential ionization cross sections of the H molecule
Fully differential cross sections are calculated for the ionization of H
by fast charged projectiles using a semiclassical model developed previously
for the ionization of atoms. The method is tested in case of 4 keV electron and
6 MeV proton projectiles. The obtained results show good agreement with the
available experimental data. Interference effects due to the two-center
character of the target are also observed and analyzed.Comment: 11 pages, 4 figure
Physical and chemical differentiation of the luminous star-forming region W49A - Results from the JCMT Spectral Legacy Survey
The massive and luminous star-forming region W49A is a well known Galactic
candidate to probe the physical conditions and chemistry similar to those
expected in external starburst galaxies. We aim to probe the physical and
chemical structure of W49A on a spatial scale of ~0.8 pc based on the JCMT
Spectral Legacy Survey, which covers the frequency range between 330 and 373
GHz. The wide 2x2 arcminutes field and the high spectral resolution of the HARP
instrument on JCMT provides information on the spatial structure and kinematics
of the cloud. For species where multiple transitions are available, we estimate
excitation temperatures and column densities. We detected 255 transitions
corresponding to 60 species in the 330-373 GHz range at the center position of
W49A. Excitation conditions can be probed for 16 molecules. The chemical
composition suggests the importance of shock-, PDR-, and hot core chemistry.
Many molecular lines show a significant spatial extent across the maps
including high density tracers (e.g. HCN, HNC, CS, HCO+) and tracers of
UV-irradiation (e.g. CN and C2H). Large variations are seen between the
sub-regions with mostly blue-shifted emission toward the Eastern tail, mostly
red-shifted emission toward the Northern clump, and emission peaking around the
expected source velocity toward the South-west clump. A comparison of column
density ratios of characteristic species observed toward W49A to Galactic PDRs
suggests that while the chemistry toward the W49A center is driven by a
combination of UV-irradiation and shocks, UV-irradiation dominates for the
Northern Clump, Eastern tail, and South-west clump regions. A comparison to a
starburst galaxy and an AGN suggests similar C2H, CN, and H2CO abundances (with
respect to the dense gas tracer 34CS) between the ~0.8 pc scale probed for W49A
and the >1 kpc regions in external galaxies with global star-formation.Comment: Proposed for acceptance in A&A, abstract abridge
A Career in Thin Air
This is a description of my 60‐year career in space science. I was lucky that my career started pretty much with the beginning of the space science era, when most measurements presented something new, exciting, and unexpected. It was also a time when there were plenty of opportunities and finding support was relatively easy.Key PointBiography of authorPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152475/1/jgra55224.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152475/2/jgra55224_am.pd
Ion Exchange Resin Impregnated Paper Chromatography of Some Typical Chlorinated Pesticides
The purpose of this project was to examine the effect the ionic immobile phase of various ion exchange resin-impregnated papers has on the separability of some typical chlorinated pesticides; the ultimate goal was devising an ion exchange resin-impregnated paper chromatographic system which would provide better chlorinated pesticide resolution than conventional paper chromatographic methods
Comment on “Ionospheric evidence of hot oxygen in the upper atmosphere of Venus”
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95022/1/grl6627.pd
CH observations toward the Orion Bar
CH is one of the first radicals to be detected in the interstellar
medium. Its higher rotational transitions have recently become available with
the Herschel Space Observatory. We aim to constrain the physical parameters of
the CH emitting gas toward the Orion Bar. We analyse the CH line
intensities measured toward the Orion Bar CO Peak and Herschel/HIFI maps of
CH, CH, and HCO, and a NANTEN map of [CI]. We interpret the observed
CH emission using radiative transfer and PDR models. Five rotational
transitions of CH have been detected in the HIFI frequency range toward the
CO peak. A single component rotational diagram gives a rotation temperature
of ~64 K and a beam-averaged CH column density of 410
cm. The measured transitions cannot be explained by any single parameter
model. According to a non-LTE model, most of the CH column density produces
the lower- CH transitions and traces a warm ( ~ 100-150 K)
and dense ((H)~10-10 cm) gas. A small fraction of the
CH column density is required to reproduce the intensity of the highest-
transitions (=9-8 and N=10-9) originating from a high density
((H)~510 cm) hot ( ~ 400 K) gas. The
total beam-averaged CH column density in the model is 10 cm.
Both the non-LTE radiative transfer model and a simple PDR model representing
the Orion Bar with a plane-parallel slab of gas and dust suggest, that CH
cannot be described by a single pressure component, unlike the reactive ion
CH, which was previously analysed toward the Orion Bar CO peak. The
physical parameters traced by the higher rotational transitions
(=6-5,...,10-9) of CH may be consistent with the edges of dense clumps
exposed to UV radiation near the ionization front of the Orion Bar.Comment: Proposed for acceptance in A&A, abstract abridge
Manual for an International Trade Data Base on the IBM Computer of the Hungarian Academy of Sciences
This manual has been prepared to allow IIASA economists to access an international trade data base stored on the IBM computer at the Hungarian Academy of Sciences in Budapest. It describes the contents of the data base and the capabilities of the data-handling program, and explains how the data base may be accessed from IIASA via the Gateway system. It is hoped that the information made available in this way will be useful in the work on economic structural change currently in progress at IIASA
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