6,570 research outputs found
Multiplate focusing collimator
An appartus is described for scanning relatively small near sources of penetrating radiation to obtain the energy distribution thereof, wherein a collimator assembly is interposed between a radiation source and a radiation detector. The collimator assembly has a plurality of plates aligned in parallel planes with respect to a common axis normal to their centers. All the plates have similar random distribution of apertures. All apertures on each plate are the same size. The size of respective plates, the size of the apertures of said respective plates, and the spacing between said respective plates vary precisely according to a predetermined ratio to produce radiation channels which converge to a focal point. The radiation incident to the radiation detector is maximized when the focal point and the radiation source are co-incident
Remarks on NonHamiltonian Statistical Mechanics: Lyapunov Exponents and Phase-Space Dimensionality Loss
The dissipation associated with nonequilibrium flow processes is reflected by
the formation of strange attractor distributions in phase space. The
information dimension of these attractors is less than that of the equilibrium
phase space, corresponding to the extreme rarity of nonequilibrium states. Here
we take advantage of a simple model for heat conduction to demonstrate that the
nonequilibrium dimensionality loss can definitely exceed the number of
phase-space dimensions required to thermostat an otherwise Hamiltonian system.Comment: 5 pages, 2 figures, minor typos correcte
Time-reversed symmetry and covariant Lyapunov vectors for simple particle models in and out of thermal equilibrium
Recently, a new algorithm for the computation of covariant Lyapunov vectors
and of corresponding local Lyapunov exponents has become available. Here we
study the properties of these still unfamiliar quantities for a number of
simple models, including an harmonic oscillator coupled to a thermal gradient
with a two-stage thermostat, which leaves the system ergodic and fully time
reversible. We explicitly demonstrate how time-reversal invariance affects the
perturbation vectors in tangent space and the associated local Lyapunov
exponents. We also find that the local covariant exponents vary discontinuously
along directions transverse to the phase flow.Comment: 13 pages, 11 figures submitted to Physical Review E, 201
Measurement of Flying Qualities of a Douglas A-26B Airplane (AAF No. 41-39120) III : Stalling Characteristics
Measurement of Flying Qualities of a Douglas A-26B Airplane (AAF No. 41-39120) II : Lateral and Directional Stability and Control Characteristics
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