19,775 research outputs found
Consistency of Random Field Specifications
A random field specification is a consistent family of conditional probability distributions parametrized by a directed set A. For a subset B ⊂ A there is the problem of determining which, if any, specifications arise from a given family of conditional probability candidates parametrized by B. For an algebraic form of this problem we give necessary and sufficient conditions for existence and uniqueness. We apply the results to one-dimensional random fields with nearest neighbour constraints
The On The Fly Imaging Technique
The On-The-Fly (OTF) imaging technique enables single-dish radio telescopes
to construct images of small areas of the sky with greater efficiency and
accuracy. This paper describes the practical application of the OTF imaging
technique. By way of example the implementation of the OTF imaging technique at
the NRAO 12 Meter Telescope is described. Specific requirements for data
sampling, image formation, and Doppler correction are discussed.Comment: 10 pages, 13 figures, accepted A&
Wind turbine generator rotor blade concepts with low cost potential
Four processed for producing blades are examined. Two use filament winding techniques and two involve filling a mold or form to produce all or part of a blade. The processes are described and a comparison is made of cost, material properties, design and free vibration characteristics. Conclusions are made regarding the feasibility of each process to produce low cost, structurally adequate blades
Giant viscosity enhancement in a spin-polarized Fermi liquid
The viscosity is measured for a Fermi liquid, a dilute He-He mixture,
under extremely high magnetic field/temperature conditions ( T, mK). The spin splitting energy is substantially greater than
the Fermi energy ; as a consequence the polarization tends to unity
and s-wave quasiparticle scattering is suppressed for . Using a
novel composite vibrating-wire viscometer an enhancement of the viscosity is
observed by a factor of more than 500 over its low-field value. Good agreement
is found between the measured viscosity and theoretical predictions based upon
a -matrix formalism.Comment: 4 pages, 4 figure
L^2 Convergence of Certain Random Walks on Z^d and related Diffusions
One technique for studying the approach to equilibrium of a continuous time Markov process is to consider the restriction to the L^2 space of an invariant distribution. When the process is reversible with respect to this distribution, the generator is a selfadjoint operator. We study the L^2 spectrum of the generator for certain random walks on Z^d, where the reversible invariant distribution is concentrated near the origin and decays rapidly with distance to the origin. For the related diffusions on R^d we find that the generators are unitarily equivalent to Schrödinger operators
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