41,078 research outputs found
Symmetry Breaking Study with Deformed Ensembles
A random matrix model to describe the coupling of m-fold symmetry in
constructed. The particular threefold case is used to analyze data on
eigenfrequencies of elastomechanical vibration of an anisotropic quartz block.
It is suggested that such experimental/theoretical study may supply powerful
means to discern intrinsic symmetries in physical systems.Comment: 12 pages, 5 figure
Large-Scale Advanced Prop-Fan (LAP) pitch change actuator and control design report
In recent years, considerable attention has been directed toward improving aircraft fuel consumption. Studies have shown that the high inherent efficiency previously demonstrated by low speed turboprop propulsion systems may now be extended to today's higher speed aircraft if advanced high-speed propeller blades having thin airfoils and aerodynamic sweep are utilized. Hamilton Standard has designed a 9-foot diameter single-rotation Large-Scale Advanced Prop-Fan (LAP) which will be tested on a static test stand, in a high speed wind tunnel and on a research aircraft. The major objective of this testing is to establish the structural integrity of large-scale Prop-Fans of advanced construction in addition to the evaluation of aerodynamic performance and aeroacoustic design. This report describes the operation, design features and actual hardware of the (LAP) Prop-Fan pitch control system. The pitch control system which controls blade angle and propeller speed consists of two separate assemblies. The first is the control unit which provides the hydraulic supply, speed governing and feather function for the system. The second unit is the hydro-mechanical pitch change actuator which directly changes blade angle (pitch) as scheduled by the control
Forecasting cosmological constraints from age of high-z galaxies
We perform Monte Carlo simulations based on current age estimates of high-z
objects to forecast constraints on the equation of state (EoS) of the dark
energy. In our analysis, we use two different EoS parameterizations, namely,
the so-called CPL and its uncorrelated form and calculate the improvements on
the figure of merit for both cases. Although there is a clear dependence of the
FoM with the size and accuracy of the synthetic age samples, we find that the
most substantial gain in FoM comes from a joint analysis involving age and
baryon acoustic oscillation data.Comment: 4 pages, 13 figures, late
Non-Linear Supersymmetric -Models and their Gauging in the Atiyah-Ward Space-Time
We present a supersymmetric non-linear \s-model built up in the
superspace of Atiyah-Ward space-time. A manifold of the K\"ahler type comes out
that is restricted by a particular decomposition of the K\"ahler potential. The
gauging of the \s-model isometries is also accomplished in superspace.Comment: 15 pages, Latex, no figure
Improved semiclassical density matrix: taming caustics
We present a simple method to deal with caustics in the semiclassical
approximation to the thermal density matrix of a particle moving on the line.
For simplicity, only its diagonal elements are considered. The only ingredient
we require is the knowledge of the extrema of the Euclidean action. The
procedure makes use of complex trajectories, and is applied to the quartic
double-well potential.Comment: 20 pages, 7 figures. Revised version, accepted for publication in
Phys. Rev.
Continuous measurement feedback control of a Bose-Einstein condensate using phase contrast imaging
We consider the theory of feedback control of a Bose-Einstein condensate
(BEC) confined in a harmonic trap under a continuous measurement constructed
via non-destructive imaging. A filtering theory approach is used to derive a
stochastic master equation (SME) for the system from a general Hamiltonian
based upon system-bath coupling. Numerical solutions for this SME in the limit
of a single atom show that the final steady state energy is dependent upon the
measurement strength, the ratio of photon kinetic energy to atomic kinetic
energy, and the feedback strength. Simulations indicate that for a weak
measurement strength, feedback can be used to overcome heating introduced by
the scattering of light, thereby allowing the atom to be driven towards the
ground state.Comment: 4 figures, 11 page
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