1,670 research outputs found
The ISM Interactions of a Runaway LBV Nebula in the LMC
New observations of the Magellanic Cloud Luminous Blue Variable candidate
S119 (HD269687) show the relationship of the star to its environs. Echelle
spectroscopy and high-resolution HST imagery reveal an expanding bubble
centered on the star. This bubble appears in both Halpha and [NII] and is
noticeably brighter on the near (blue-shifted) side. The systemic velocity of
both the expanding bubble and the star itself (as seen by the very broad Halpha
emission feature in the stellar spectrum) is V_hel=160 km/s whereas the
velocity of the superposed LMC ISM is 250-300 km/s. ISM absorption features
seen in FUSE spectra reveal components at both stellar and LMC velocities. Thus
we conclude that S119 is located within the LMC ISM and that the bubble is
interacting strongly with the ISM in a bow shock.Comment: 5 pages in EmulateApJ format, 3 figures Accepted by ApJL See
http://fuse.pha.jhu.edu/~danforth/s119
An examination of the contribution and function of the music workshop in the in-service education of the classroom teacher
Thesis (M.M.)--Boston Universit
The full-scale process and design changes for elimination of insulation edge separations and voids in tang flap area
Qualification of the full-scale process and design changes for elimination of redesigned solid rocket motor tang nitrile butadiene rubber insulation edge separations and voids was performed from 24 March to 3 December 1990. The objectives of this test were: to qualify design and process changes on flight hardware using a tie ply between the redesigned solid rocket motor steel case and the nitrile butadiene rubber insulation over the tang capture features; to qualify the use of methyl ethyl ketone in the tang flap region to reduce voids; and to determine if holes in the separator film reduce voids in the tang flap region. The tie ply is intended to aid insulation flow during the insulation cure process, and thus reduce or eliminate edge unbonds. Methyl ethyl ketone is intended to reduce voids in the tang flap area by providing better tacking characteristics. The perforated film was intended to provide possible vertical breathe paths to reduce voids in the tang area. Tang tie ply testing consisted of 270 deg of the tang circumference using a new layup method and 90 deg of the tang circumference using the current layup methods. Tie ply process success was defined as a reduction of insulation unbonds. Lack of any insulation edge unbonds on the tang area where the new process was used, and the presence of 17 unbonds with the current process, proves the test to be a success. Successful completion of this test has qualified the new processes
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Virtual Simulation for Multi-material LM Process
In an ONR funded MURI program, to improve quality of multi-material parts,
we've been developing an advanced computer simulation for the multi-material layered
manufacturing (LM) process. The CAD models and their .stLfiles are created using. the
commercially available software such as I-DEAS and ProE. Using this information, one
tool path file per material is generated. Our file preparation algorithm, systematically,
layer by layer, integrates all tool path files into one multi-material tool path file. The
results of the multi-material tool path are graphically visualized using the simulation
algorithm (written in c++ & SGI OpenGL). From a virtual simulation, we can check the
LM process, and make the best selection of tool path parameters afterwards. After several
trials from design to simulation, if the simulation result is acceptable, the real
manufacturing can be started. And the part's quality should be better than a part
manufactured without running simulation in advance. This paper will represent .•. new
studies on using real toadshapes to get more realistic simulation results. Many parts have
been successfully simulated using our method.Mechanical Engineerin
A Detection of Gas Associated with the M 31 Stellar Stream
Detailed studies of stellar populations in the halos of the Milky Way and the
Andromeda (M 31) galaxies have shown increasing numbers of tidal streams and
dwarf galaxies, attesting to a complicated and on-going process of hierarchical
structure formation. The most prominent feature in the halo of M 31 is the
Giant Stellar Stream, a structure ~4.5 degrees in extent along the sky, which
is close to, but not coincident with the galaxy's minor axis. The stars that
make up this stream are kinematically and chemically distinct from the other
stars in the halo. Here, we present HST/COS high-resolution ultraviolet
absorption spectra of three Active Galactic Nuclei sight lines which probe the
M 31 halo, including one that samples gas in the main southwestern portion of
the Giant Stream. We see two clear absorption components in many metal species
at velocities typical of the M 31 halo and a third, blue-shifted component
which arises in the stream. Photoionization modeling of the column density
ratios in the different components shows gas in an ionization state typical of
that seen in other galaxy halo environments and suggests solar to slightly
super-solar metallicity, consistent with previous findings from stellar
spectroscopy.Comment: 10 pages, 5 figures, accepted for publication in the Astrophysical
Journa
Environmental Data Recorder (EDR) qualification
Qualification testing of the environmental data recorder (EDR) was successfully completed. The purpose of this test was to qualify the EDR so that it could monitor segments shipped via railcar from Utah to Kennedy Space Center (KSC). The tests consisted of a transportation and a functional test. The transportation test verified EDR operation in its intended environment. The functional test verified EDR accuracy. Data from the functional test showed that the EDR accuracies complied with requirements. Since the EDR meets or exceeds all of its test objectives, it was successfully qualified. It is recommended that the EDR replace the transportation monitoring unit (TMU). A description of the qualification procedure is presented
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Generation of Porous Structures Using Fused Deposition
The Fused Deposition Modeling process uses hardware and software machine-level
language that are very similar to that of a pen-plotter. Consequently, the·use of patterns with
poly-lines as basic geometric features, instead of the current method based on filled polygons
(monolithic models), can increase its efficiency.
In the current study, various toolpath planning methods have been developed to fabricate
porous structures. Computational domain decomposition methods can be applied to the physical
or to slice-level domains to generate structured and unstructured grids. Also, textures can be
created using periodic tiling of the layer with unit cells (squares, honeycombs, etc). Methods
'based on curves include fractal space filling curves and.change of effective road width Within a
layer or within a continuous curve. Individual phases can also be placed in binary compositions.
In present investigation, a custom software has been developed and implemented to
generate build files (SML) and slice files (SSL) for the above-mentioned structures, demonstrating the efficient control ofthe size, shape, and distribution ofporosity.Mechanical Engineerin
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