2,488 research outputs found
Space shuttle pogo studies
Topics covered include: (1) pogo suppression for main propulsion subsystem operation; (2) application of quarter-scale low pressure oxidizer turbopump transfer functions; (3) pogo stability during orbital maneuvering subsystem operation; and (4) errors in frequency response measurements
Phase-locking at low-level of quanta
We discuss phase-locking phenomena at low-level of quanta for parametrically
driven nonlinear Kerr resonator (PDNR) in strong quantum regime. Oscillatory
mode of PDNR is created in the process of a degenerate down-conversion of
photons under interaction with a train of external Gaussian pulses. We
calculate the Wigner functions of cavity mode showing two-fold symmetry in
phase space and analyse formation of phase-locked states in the regular as well
as the quantum chaotic regime.Comment: 6 pages, 4 figure
An Aerothermoelastic Analysis Framework Enhanced by Model Order Reduction With Applications
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143034/1/6.2017-1601.pd
Objective Function and Constraints for Robust Transonic Aerofoil Optimization
Construction of the aerodynamic optimization problem is considered within the context of robustness. The most common aerodynamic optimization problem considered is a lift-constrained drag minimization problem (also subject to geometric constraints), however, point-design at transonic flow conditions can produce shock-free solutions and therefore the result is highly localised, where the gains obtained at the design point are outweighed by the losses at off-design conditions. As such, a range optimization problem subject to a constraint on fixed non-dimensional lift with a varying design point is considered to mitigate this issue. It is shown, first from an analytical treatment of the problem, and second from inviscid optimizations, that more robust solutions are obtainable when considering range optimization against drag minimization. Furthermore, to effectively capture the trade-offs that exist in three-dimensional aircraft design between range, lift, drag and speed, it is shown that an induced drag factor is required and this is suffcient to produce optimal solutions exhibiting shocks
Electron attachment to valence-excited CO
The possibility of electron attachment to the valence state of CO
is examined using an {\it ab initio} bound-state multireference configuration
interaction approach. The resulting resonance has symmetry;
the higher vibrational levels of this resonance state coincide with, or are
nearly coincident with, levels of the parent state. Collisional
relaxation to the lowest vibrational levels in hot plasma situations might
yield the possibility of a long-lived CO state.Comment: Revtex file + postscript file for one figur
Quantum Relativity of Subsystems
One of the most basic notions in physics is the partitioning of a system into
subsystems, and the study of correlations among its parts. In this work, we
explore these notions in the context of quantum reference frame (QRF)
covariance, in which this partitioning is subject to a symmetry constraint. We
demonstrate that different reference frame perspectives induce different sets
of subsystem observable algebras, which leads to a gauge-invariant,
frame-dependent notion of subsystems and entanglement. We further demonstrate
that subalgebras which commute before imposing the symmetry constraint can
translate into non-commuting algebras in a given QRF perspective after symmetry
imposition. Such a QRF perspective does not inherit the distinction between
subsystems in terms of the corresponding tensor factorizability of the
kinematical Hilbert space and observable algebra. Since the condition for this
to occur is contingent on the choice of QRF, the notion of subsystem locality
is frame-dependent.Comment: 8+9 pages, 1 figur
High resolution Compton scattering as a Probe of the Fermi surface in the Iron-based superconductor
We have carried out first principles all-electron calculations of the
(001)-projected 2D electron momentum density and the directional Compton
profiles along the [100], [001] and [110] directions in the Fe-based
superconductor LaOFeAs within the framework of the local density approximation.
We identify Fermi surface features in the 2D electron momentum density and the
directional Compton profiles, and discuss issues related to the observation of
these features via Compton scattering experiments.Comment: 4 pages, 3 figure
Fermi Surface as the Driving Mechanism for Helical Antiferromagnetic Ordering in Gd-Y Alloys
The first direct experimental evidence for the Fermi surface (FS) driving the
helical antiferromagnetic ordering in a gadolinium-yttrium alloy is reported.
The presence of a FS sheet capable of nesting is revealed, and the nesting
vector associated with the sheet is found to be in excellent agreement with the
periodicity of the helical ordering.Comment: 4 pages, 4 figure
Reliability and validity of a novel haemophilia-specific self-efficacy scale
Higher self-efficacy in chronic disease patients is associated with higher development of self-management skills and increased quality-of-life. Quantification and monitoring of self-efficacy is therefore of importance. Self-efficacy in haemophilia patients has received little attention due to lack of standardized scales. To validate the novel Haemophilia-specific Self-Efficacy Scale (HSES) in haemophilia patients on prophylactic home treatment, haemophilia patients aged 1-18 years on prophylactic treatment ≥1 year were included from three Dutch Haemophilia Treatment Centres. The HSES consists of 12 items, relating to perceptions of the ability to function on a day-to-day basis with regard to patient's disease. Retest was performed in a subsample. Validity was proven by the General Self-Efficacy Scale and by the health-related quality-of-life assessment tool Haemo-QoL. Data were analysed from 53 children (response 75%), with a mean age of 9.8 years (SD 4.0). Mean total scale score of HSES was 55.5 (SD 4.7; range 38-60), with a ceiling effect of 17%. The HSES showed adequate internal consistency (Cronbach's alpha 0.72) and good test-retest reliability (Intra-Class-Correlation coefficient 0.75; P < 0.01; n = 37). The convergent validity was adequate as haemophilia-specific self-efficacy correlated significantly with general self-efficacy (r = 0.38; P < 0.01). High HSES scores correlated significantly with quality-of-life as measured by the Haemo-QoL (r = -0.42; P ≤ 0.01). The novel HSES is a reliable and valid tool to assess self-efficacy in paediatric haemophilia patients on prophylactic home treatment. High self-efficacy correlated with higher quality-of-life, further underlining the importance to standardly assess, monitor and improve self-efficacy
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