2,675 research outputs found
SBASI: Actuated pyrotechnic time delay initiator
A precision pyrotechnic time delay initiator for missile staging was developed and tested. Incorporated in the assembly is a single bridgewire Apollo standard initiator (SBASI) for initiation, a through-bulkhead-initiator to provide isolation of the SBASI output from the delay, the pyrotechnic delay, and an output charge. An attempt was made to control both primary and secondary variables affecting functional performance of the delay initiator. Design and functional limit exploration was performed to establish tolerance levels on manufacturing and assembling operations. The test results demonstrate a 2% coefficient of variation at any one temperature and an overall 2.7% coefficient of variation throughout the temperature range of 30 to 120 F. Tests were conducted at simulated operational altitude from sea level to 200,000 feet
Enhancing Online or Blended Learning Environments with Active Learning
Active learning is more than just a trending buzzword. This paper explores engaging strategies that are evidence-based instructional practices. With a little creativity and technology, these strategies can easily be implemented in any online or blended learning environment to engage learners and increase student learning outcomes
Hydrogen thermal conductivity at temperatures from 2000 to 4000 deg F Final report
Hydrogen thermal conductivity at temperatures from 2000 to 4600 deg
SSME lifetime prediction and verification, integrating environments, structures, materials: The challenge
The planned missions for the space shuttle dictated a unique and technology-extending rocket engine. The high specific impulse requirements in conjunction with a 55-mission lifetime, plus volume and weight constraints, produced unique structural design, manufacturing, and verification requirements. Operations from Earth to orbit produce severe dynamic environments, which couple with the extreme pressure and thermal environments associated with the high performance, creating large low cycle loads and high alternating stresses above endurance limit which result in high sensitivity to alternating stresses. Combining all of these effects resulted in the requirements for exotic materials, which are more susceptible to manufacturing problems, and the use of an all-welded structure. The challenge of integrating environments, dynamics, structures, and materials into a verified SSME structure is discussed. The verification program and developmental flight results are included. The first six shuttle flights had engine performance as predicted with no failures. The engine system has met the basic design challenges
Ks band secondary eclipses of WASP-19b and WASP-43b with the Anglo-Australian Telescope
We report new Ks band secondary eclipse observations for the hot-Jupiters
WASP-19b and WASP-43b. Using the IRIS2 infrared camera on the Anglo-Australian
Telescope (AAT), we measured significant secondary eclipses for both planets,
with depths of 0.287 -0.020/+0.020% and 0.181 -0.027/+0.027% for WASP-19b and
WASP-43b respectively. We compare the observations to atmosphere models from
the VSTAR line-by-line radiative transfer code, and examine the effect of C/O
abundance, top layer haze, and metallicities on the observed spectra. We
performed a series of signal injection and recovery exercises on the observed
light curves to explore the detection thresholds of the AAT+IRIS2 facility. We
find that the optimal photometric precision is achieved for targets brighter
than Kmag = 9, for which eclipses as shallow as 0.05% are detectable at >5
sigma significance.Comment: Accepted for publication in MNRAS, 13 pages, 10 figure
Fast and Slow Rotators in the Densest Environments: a SWIFT IFS study of the Coma Cluster
We present integral-field spectroscopy of 27 galaxies in the Coma cluster
observed with the Oxford SWIFT spectrograph, exploring the kinematic
morphology-density relationship in a cluster environment richer and denser than
any in the ATLAS3D survey. Our new data enables comparison of the kinematic
morphology relation in three very different clusters (Virgo, Coma and Abell
1689) as well as to the field/group environment. The Coma sample was selected
to match the parent luminosity and ellipticity distributions of the early-type
population within a radius 15' (0.43 Mpc) of the cluster centre, and is limited
to r' = 16 mag (equivalent to M_K = -21.5 mag), sampling one third of that
population. From analysis of the lambda-ellipticity diagram, we find 15+-6% of
early-type galaxies are slow rotators; this is identical to the fraction found
in the field and the average fraction in the Virgo cluster, based on the
ATLAS3D data. It is also identical to the average fraction found recently in
Abell 1689 by D'Eugenio et al.. Thus it appears that the average slow rotator
fraction of early type galaxies remains remarkably constant across many
different environments, spanning five orders of magnitude in galaxy number
density. However, within each cluster the slow rotators are generally found in
regions of higher projected density, possibly as a result of mass segregation
by dynamical friction. These results provide firm constraints on the mechanisms
that produce early-type galaxies: they must maintain a fixed ratio between the
number of fast rotators and slow rotators while also allowing the total
early-type fraction to increase in clusters relative to the field. A complete
survey of Coma, sampling hundreds rather than tens of galaxies, could probe a
more representative volume of Coma and provide significantly stronger
constraints, particularly on how the slow rotator fraction varies at larger
radii.Comment: Accepted for publication in MNRA
WISE J163940.83-684738.6: A Y Dwarf identified by Methane Imaging
We have used methane imaging techniques to identify the near-infrared
counterpart of the bright WISE source WISEJ163940.83-684738.6. The large proper
motion of this source (around 3.0arcsec/yr) has moved it, since its original
WISE identification, very close to a much brighter background star -- it
currently lies within 1.5" of the J=14.90+-0.04 star 2MASS16394085-6847446.
Observations in good seeing conditions using methane sensitive filters in the
near-infrared J-band with the FourStar instrument on the Magellan 6.5m Baade
telescope, however, have enabled us to detect a near-infrared counterpart. We
have defined a photometric system for use with the FourStar J2 and J3 filters,
and this photometry indicates strong methane absorption, which unequivocally
identifies it as the source of the WISE flux. Using these imaging observations
we were then able to steer this object down the slit of the FIRE spectrograph
on a night of 0.6" seeing, and so obtain near-infrared spectroscopy confirming
a Y0-Y0.5 spectral type. This is in line with the object's
near-infrared-to-WISE J3--W2 colour. Preliminary astrometry using both WISE and
FourStar data indicates a distance of 5.0+-0.5pc and a substantial tangential
velocity of 73+-8km/s. WISEJ163940.83-684738.6 is the brightest confirmed Y
dwarf in the WISE W2 passband and its distance measurement places it amongst
the lowest luminosity sources detected to date.Comment: Accepted for publication in The Astrophysical Journal, 20 September
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Designing Performer Training: Digital Encounters with Things and People
This article investigates how digital technologies can be used to enhance the relational aspects of performer training. Saner and Robinson reflect on a practice as research project, Enactive Encounters, where they use poor technology and everyday objects to create participatory learning environments. The teacher- student relationship is challenged and transformed into playful interactions between participants through enactive encounters that aim to embody different aspects of specific training practices.
Keywords: digital training, relational pedagogy, enactivism
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