15,790 research outputs found
Development of material specifications and qualifications of polymeric materials for the jpl spacecraft materials guide book. iii- polyfluorocarbon films special report no. 3
Outgassing studies of polyfluorocarbon films - investigation of polymers as spacecraft construction material
Quantum Flux and Reverse Engineering of Quantum Wavefunctions
An interpretation of the probability flux is given, based on a derivation of
its eigenstates and relating them to coherent state projections on a quantum
wavefunction. An extended definition of the flux operator is obtained using
coherent states. We present a "processed Husimi" representation, which makes
decisions using many Husimi projections at each location. The processed Husimi
representation reverse engineers or deconstructs the wavefunction, yielding the
underlying classical ray structure. Our approach makes possible interpreting
the dynamics of systems where the probability flux is uniformly zero or
strongly misleading. The new technique is demonstrated by the calculation of
particle flow maps of the classical dynamics underlying a quantum wavefunction.Comment: Accepted to EP
Space probe/satellite ejection apparatus for spacecraft
An ejection apparatus for spinning and propelling objects for ejection from a spacecraft at a desired velocity and rotational speed is discussed. The apparatus includes a launch cradle on which the space object to be ejected rests. The cradle is rotatably supported by a central hub secured to the upper end of the pneumatic cylinder piston shaft. Release mechanisms consisting of a retractable pin and locking lug is utilized to hold the cradle and object to be ejected. The release mechanism has a fixed barrier member which holds the retractable pin in engagement with the locking lug until release by upward movement of the launch cradle beyond the barrier height
Computer experiments to determine whether over- or under-counting necessarily affects the determination of difference in cell number between experimental groups
Cataloged from PDF version of article.Computer cell counting experiments were performed in order to examine the consequences of over- or under-counting. The
three-dimensional reaggregate culture laboratory environment for cell counting was used as a model for computer simulation. The
laboratory environment for aggregate and cell sizes, numbers and spatial placement in gelatin blocks was mimicked in the
computer setup. However, in the computer, cell counting was set to be either ideally unbiased, or deliberately biased in regard to
over- or under-counting so as to compare eventual results when using the various cell counting methods. It was found that there
was no effect of the cell counting methods used in determining whether there was a significant difference in cell number between
two experimental groups. In addition, it was found that under the conditions of these simulations, the optical disector method
behaved similarly, on the average, as the ideal method of counting cell centers and in both of those cases, the average ratio
between actual cell number in a flask and estimated number was close to 1.00. © 2001 Elsevier Science B.V. All rights reserved
Phase-space correlations of chaotic eigenstates
It is shown that the Husimi representations of chaotic eigenstates are
strongly correlated along classical trajectories. These correlations extend
across the whole system size and, unlike the corresponding eigenfunction
correlations in configuration space, they persist in the semiclassical limit. A
quantitative theory is developed on the basis of Gaussian wavepacket dynamics
and random-matrix arguments. The role of symmetries is discussed for the
example of time-reversal invariance.Comment: Published version with minor corrections to version
Modelling the quark propagator
The quark propagator is at the core of lattice hadron spectrum calculations
as well as studies in other nonperturbative schemes. We investigate the quark
propagator with an improved staggered action (Asqtad) and an improved gluon
action, which provides good quality data down to small quark masses. This is
used to construct ans\"{a}tze suitable for model hadron calculations as well as
adding to our intuitive understanding of QCD.Comment: Lattice2002(spectrum
Scarring by homoclinic and heteroclinic orbits
In addition to the well known scarring effect of periodic orbits, we show
here that homoclinic and heteroclinic orbits, which are cornerstones in the
theory of classical chaos, also scar eigenfunctions of classically chaotic
systems when associated closed circuits in phase space are properly quantized,
thus introducing strong quantum correlations. The corresponding quantization
rules are also established. This opens the door for developing computationally
tractable methods to calculate eigenstates of chaotic systems.Comment: 5 pages, 4 figure
Observing trajectories with weak measurements in quantum systems in the semiclassical regime
We propose a scheme allowing to observe the evolution of a quantum system in
the semiclassical regime along the paths generated by the propagator. The
scheme relies on performing consecutive weak measurements of the position. We
show how weak trajectories" can be extracted from the pointers of a series of
measurement devices having weakly interacted with the system. The properties of
these "weak trajectories" are investigated and illustrated in the case of a
time-dependent model system.Comment: v2: Several minor corrections were made. Added Appendix (that will
appear as Suppl. Material). To be published in Phys Rev Let
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