53,183 research outputs found

    On the divine clockwork: the spectral gap for the correspondence limit of the Nelson diffusion generator for the atomic elliptic state

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    The correspondence limit of the atomic elliptic state in three dimensions is discussed in terms of Nelson's stochastic mechanics. In previous work we have shown that this approach leads to a limiting Nelson diffusion and here we discuss in detail the invariant measure for this process and show that it is concentrated on the Kepler ellipse in the plane z=0. We then show that the limiting Nelson diffusion generator has a spectral gap; thereby proving that in the infinite time limit the density for the limiting Nelson diffusion will converge to its invariant measure. We also include a summary of the Cheeger and Poincare inequalities both of which are used in our proof of the existence of the spectral gap.Comment: 30 pages, 5 figures, submitted to J. Math. Phy

    Foolproof quick-release locking pin

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    Locking pin can be withdrawn only when stress on the joint is negligible. Pin consists of a forward-pointing sleeve, a spring-loaded sliding handle, and a sliding plunger. Plunger movement controls installation and withdrawal of pin

    Strain Rate Sensitive Constitutive Equations

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    Stain rate sensitive constitutive equations using yield criterion which incorporates second and third invariants of stress deviato

    The preparation and evaluation of high-purity, fine-grained tungsten and tungsten alloy castings summary report

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    High purity, cylindrical castings of high melting point materials such as tungsten and tungsten alloy

    Analysis of an F.M. Discriminator with Fading Signal plus Additive Gaussian Noise

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    Fading signal plus additive Gaussian noise applied to frequency modulation discriminator for determining fading effects on threshol

    Extension of geodesic algebras to continuous genus

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    Using the Penner--Fock parameterization for Teichmuller spaces of Riemann surfaces with holes, we construct the string-like free-field representation of the Poisson and quantum algebras of geodesic functions in the continuous-genus limit. The mapping class group acts naturally in the obtained representation.Comment: 16 pages, submitted to Lett.Math.Phy

    A Universal Temperature Profile for Galaxy Clusters

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    We investigate the predicted present-day temperature profiles of the hot, X-ray emitting gas in galaxy clusters for two cosmological models - a current best-guess LCDM model and standard cold dark matter (SCDM). Our numerically-simulated "catalogs" of clusters are derived from high-resolution (15/h kpc) simulations which make use of a sophisticated, Eulerian-based, Adaptive Mesh-Refinement (AMR) code that faithfully captures the shocks which are essential for correctly modelling cluster temperatures. We show that the temperature structure on Mpc-scales is highly complex and non-isothermal. However, the temperature profiles of the simulated LCDM and SCDM clusters are remarkably similar and drop-off as T+AFw−propto(1+−r/ax)−+AFw−deltaT +AFw-propto (1+-r/a_x)^{-+AFw-delta} where ax+AFw−simrvir/1.5a_x +AFw-sim r_{vir}/1.5 and +AFw−delta+AFw−sim1.6+AFw-delta +AFw-sim 1.6. This decrease is in good agreement with the observational results of Markevitch et al.(1998) but diverges, primarily in the innermost regions, from their fit which assumes a polytropic equation of state. Our result is also in good agreement with a recent sample of clusters observed by BeppoSAX though there is some indication of missing physics at small radii (r<0.2rvirr<0.2 r_{vir}). We discuss the interpretation of our results and make predictions for new x-ray observations that will extend to larger radii than previously possible. Finally, we show that, for r>0.2rvirr>0.2 r_{vir}, our universal temperature profile is consistent with our most recent simulations which include both radiative cooling and supernovae feedback.Comment: 8 pages, 6 figures, accepted for publication in ApJ, full-page version of Fig. 2 at http://www.cita.utoronto.ca/+AH4-cloken/PAPERS/UTP/f2.ep

    The Divine Clockwork: Bohr's correspondence principle and Nelson's stochastic mechanics for the atomic elliptic state

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    We consider the Bohr correspondence limit of the Schrodinger wave function for an atomic elliptic state. We analyse this limit in the context of Nelson's stochastic mechanics, exposing an underlying deterministic dynamical system in which trajectories converge to Keplerian motion on an ellipse. This solves the long standing problem of obtaining Kepler's laws of planetary motion in a quantum mechanical setting. In this quantum mechanical setting, local mild instabilities occur in the Kelperian orbit for eccentricities greater than 1/\sqrt{2} which do not occur classically.Comment: 42 pages, 18 figures, with typos corrected, updated abstract and updated section 6.

    An investigation of the thermal radiation properties of certain spacecraft materials Final report

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    Thermal radiation analysis for anodized aluminum - anodizing process evaluation for optimum properties under space conditions for spacecraft temperature contro
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