14,990 research outputs found
Top Down Implementation Plan for system performance test software
The top down implementation plan used for the development of system performance test software during the Mark IV-A era is described. The plan is based upon the identification of the hierarchical relationship of the individual elements of the software design, the development of a sequence of functionally oriented demonstrable steps, the allocation of subroutines to the specific step where they are first required, and objective status reporting. The results are: determination of milestones, improved managerial visibility, better project control, and a successful software development
Passenger ride quality determined from commercial airline flights
The University of Virginia ride-quality research program is reviewed. Data from two flight programs, involving seven types of aircraft, are considered in detail. An apparatus for measuring physical variations in the flight environment and recording the subjective reactions of test subjects is described. Models are presented for predicting the comfort response of test subjects from the physical data, and predicting the overall comfort reaction of test subjects from their moment by moment responses. The correspondence of mean passenger comfort judgments and test subject response is shown. Finally, the models of comfort response based on data from the 5-point and 7-point comfort scales are shown to correspond
Application of ride quality technology to predict ride satisfaction for commuter-type aircraft
A method was developed to predict passenger satisfaction with the ride environment of a transportation vehicle. This method, a general approach, was applied to a commuter-type aircraft for illustrative purposes. The effect of terrain, altitude and seat location were examined. The method predicts the variation in passengers satisfied for any set of flight conditions. In addition several noncommuter aircraft were analyzed for comparison and other uses of the model described. The method has advantages for design, evaluation, and operating decisions
The effect of a random sampling interval on a sampled-data model of the human operator
Effect of random sampling interval on sampled data model of human operator in compensatory trackin
On the orientational ordering of long rods on a lattice
We argue that a system of straight rigid rods of length k on square lattice
with only hard-core interactions shows two phase transitions as a function of
density, rho, for k >= 7. The system undergoes a phase transition from the
low-density disordered phase to a nematic phase as rho is increased from 0, at
rho = rho_c1, and then again undergoes a reentrant phase transition from the
nematic phase to a disordered phase at rho = rho_c2 < 1.Comment: epl.cl
Generalized Lagrangian of N = 1 supergravity and its canonical constraints with the real Ashtekar variable
We generalize the Lagrangian of N = 1 supergravity (SUGRA) by using an
arbitrary parameter , which corresponds to the inverse of Barbero's
parameter . This generalized Lagrangian involves the chiral one as a
special case of the value . We show that the generalized
Lagrangian gives the canonical formulation of N = 1 SUGRA with the real
Ashtekar variable after the 3+1 decomposition of spacetime. This canonical
formulation is also derived from those of the usual N = 1 SUGRA by performing
Barbero's type canonical transformation with an arbitrary parameter . We give some comments on the canonical formulation of the theory.Comment: 17 pages, LATE
Origin of the Thermal Radiation in a Solid-State Analog of a Black-Hole
An effective black-hole-like horizon occurs, for electromagnetic waves in
matter, at a surface of singular electric and magnetic permeabilities. In a
physical dispersive medium this horizon disappears for wave numbers with
. Nevertheless, it is shown that Hawking radiation is still emitted if
free field modes with are in their ground state.Comment: 13 Pages, 3 figures, Revtex with epsf macro
Nanowire Acting as a Superconducting Quantum Interference Device
We present the results from an experimental study of the magneto-transport of
superconducting wires of amorphous Indium-Oxide, having widths in the range 40
- 120 nm. We find that, below the superconducting transition temperature, the
wires exhibit clear, reproducible, oscillations in their resistance as a
function of magnetic field. The oscillations are reminiscent of those which
underlie the operation of a superconducting quantum interference device.Comment: 4 pages, 4 figures, 1 tabl
Signaling, Entanglement, and Quantum Evolution Beyond Cauchy Horizons
Consider a bipartite entangled system half of which falls through the event
horizon of an evaporating black hole, while the other half remains coherently
accessible to experiments in the exterior region. Beyond complete evaporation,
the evolution of the quantum state past the Cauchy horizon cannot remain
unitary, raising the questions: How can this evolution be described as a
quantum map, and how is causality preserved? What are the possible effects of
such nonstandard quantum evolution maps on the behavior of the entangled
laboratory partner? More generally, the laws of quantum evolution under extreme
conditions in remote regions (not just in evaporating black-hole interiors, but
possibly near other naked singularities and regions of extreme spacetime
structure) remain untested by observation, and might conceivably be non-unitary
or even nonlinear, raising the same questions about the evolution of entangled
states. The answers to these questions are subtle, and are linked in unexpected
ways to the fundamental laws of quantum mechanics. We show that terrestrial
experiments can be designed to probe and constrain exactly how the laws of
quantum evolution might be altered, either by black-hole evaporation, or by
other extreme processes in remote regions possibly governed by unknown physics.Comment: Combined, revised, and expanded version of quant-ph/0312160 and
hep-th/0402060; 13 pages, RevTeX, 2 eps figure
A rapidly expanding Bose-Einstein condensate: an expanding universe in the lab
We study the dynamics of a supersonically expanding ring-shaped Bose-Einstein
condensate both experimentally and theoretically. The expansion redshifts
long-wavelength excitations, as in an expanding universe. After expansion,
energy in the radial mode leads to the production of bulk topological
excitations -- solitons and vortices -- driving the production of a large
number of azimuthal phonons and, at late times, causing stochastic persistent
currents. These complex nonlinear dynamics, fueled by the energy stored
coherently in one mode, are reminiscent of a type of "preheating" that may have
taken place at the end of inflation.Comment: 12 pages, 7 figure
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