1,462 research outputs found
SSME structural dynamic model development
The high pressure fuel turbopump (HPFTP) is a major component of the Space Shuttle Main Engine (SSME) powerhead. The device is a three stage centrifugal pump that is directly driven by a two stage hot gas turbine. The purpose of the pump is to deliver fuel (liquid hydrogen) from the low pressure fuel turbopump (LPFTP) through the main fuel valve (MFV) to the thrust chamber coolant circuits. In doing so, the pump pressurizes the fuel from an inlet pressure of approximately 178 psi to a discharge pressure of over 6000 psi. At full power level (FPL), the pump rotates at a speed of over 37,000 rpm while generating approximately 77,000 horsepower. Obviously, a pump failure at these speeds and power levels could jeopardize the mission. Results are summarized for work in which the solutions obtained from analytical models of the fuel turbopump impellers are compared with the results obtained from dynamic tests
Early and Late-Time Observations of SN 2008ha: Additional Constraints for the Progenitor and Explosion
We present a new maximum-light optical spectrum of the the extremely low
luminosity and exceptionally low energy Type Ia supernova (SN Ia) 2008ha,
obtained one week before the earliest published spectrum. Previous observations
of SN 2008ha were unable to distinguish between a massive star and white dwarf
origin for the SN. The new maximum-light spectrum, obtained one week before the
earliest previously published spectrum, unambiguously shows features
corresponding to intermediate mass elements, including silicon, sulfur, and
carbon. Although strong silicon features are seen in some core-collapse SNe,
sulfur features, which are a signature of carbon/oxygen burning, have always
been observed to be weak in such events. It is therefore likely that SN 2008ha
was the result of a thermonuclear explosion of a carbon-oxygen white dwarf.
Carbon features at maximum light show that unburned material is present to
significant depths in the SN ejecta, strengthening the case that SN 2008ha was
a failed deflagration. We also present late-time imaging and spectroscopy that
are consistent with this scenario.Comment: ApJL, accepted. 5 pages, 3 figure
A non-perturbative study of the action parameters for anisotropic-lattice quarks
A quark action designed for highly anisotropic lattice simulations is
discussed. The mass-dependence of the parameters in the action is studied and
the results are presented. Applications of this action in studies of heavy
quark quantities are described and results are presented from simulations at an
anisotropy of six, for a range of quark masses from strange to bottom.Comment: 9 pages, 8 figure
An investigation of how the Catholic tradition of educational thought might be given new articulation in the light of selected aspects of the work of three contemporary philosophers
This thesis exam ines the work o f three philosophers - Jacques M aritain, Bernard
Lonergan and Terence H. M cLaughlin - with a view to recovering from their
educational w ritings important insights and approaches pertinent to the task o f giving
new articulation to Catholic philosophy o f education today.
Having noted the virtual disappearance o f the Thom ist-A ristotelian tradition in Catholic
educational discourse over the past half-century, the thesis seeks to identify in these
authors elements that suggest new perspectives on the Catholic educational tradition in
a postm odern age.
The thesis selects aspects of the work o f these thinkers that m erit critical appraisal in
any attempt to give a systematic and detailed expression to the Catholic tradition o f
educational thought today, namely: (1) M aritain’s integral Christian humanism, (2)
Lonergan’s transcendental method, and (3) M cLauglin’s notion and practice o f
pedagogic phronesis.
This study concludes with a reflection on how selected aspects o f the work o f these
scholars m ight complement and strengthen the Congregation for Catholic Education’s
discourse in term s o f the provision of a philosophic basis and fram ew ork o f analysis
Practical all-to-all propagators for lattice QCD
A new method for computing all elements of the lattice quark propagator is
proposed. The method combines the spectral decomposition of the propagator,
computing the lowest eigenmodes exactly, with noisy estimators which are
'diluted', i.e. taken to have support only on a subset of time, space, spin or
colour. We find that the errors are dramatically reduced compared to
traditional noisy estimator techniques.Comment: 24 pages, 18 figure
Gait Analysis of Teenagers and Young Adults Diagnosed with Autism & Severe Verbal Communication Disorders
Both movement differences and disorders are common within autism spectrum disorders (ASD). These differences have wide and heterogeneous variability among different ages and sub-groups all diagnosed with ASD. Gait was studied in a more homogeneously identified group of nine teenagers and young adults who scored as “severe” in both measures of verbal communication and overall rating of Autism on the Childhood Autism Rating Scales (CARS). The ASD individuals were compared to a group of typically developing university undergraduates of similar ages. All participants walked a distance of 6-meters across a GAITRite (GR) electronic walkway for six trials. The ASD and comparison groups differed widely on many spatiotemporal aspects of gait including: step and stride length, foot positioning, cadence, velocity, step time, gait cycle time, swing time, stance time, and single and double support time. Moreover, the two groups differed in the percentage of the total gait cycle in each of these phases. The qualitative rating of “Body Use” on the CARS also indicated severe levels of unusual body movement for all of the ASD participants. These findings demonstrate that older teens and young adults with “severe” forms of Verbal Communication Impairments and Autism differ widely in their gait from typically developing individuals. The differences found in the current investigation are far more pronounced compared to previous findings with younger and/or less severely involved individuals diagnosed with ASD as compared to typically developing controls. As such, these data may be a useful anchor-point in understanding the trajectory of development of gait specifically and motor functions generally.
- …