117,888 research outputs found

    Design and analysis of a piezoelectric film embedded smart cutting tool

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    This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2012 Institution of Mechanical Engineers.The condition of a cutting tool is an important factor for manufacturing processes. Tool wear has a strong influence on the cutting forces, resulting in poor surface roughness and dimensional accuracy of the workpiece. Therefore, the use of a dynamometer to measure cutting forces is a well-known approach, but it has several limitations such as high cost, poor performance in harsh industrial machining environments and possible interference with cutting dynamics. This article presents a novel smart cutting tool using a separate single-layer piezoelectric film as the sensing unit to detect the orthogonal cutting force. Simulations were performed to validate the feasibility of the proposed design, and the model was also able to detect better force measurement sensitivity. Furthermore, cutting trials were carried out to validate cutting tool performance experimentally

    The symmetry of large N=4 holography

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    For the proposed duality relating a family of N=4 superconformal coset models to a certain supersymmetric higher spin theory on AdS_3, the asymptotic symmetry algebra of the bulk description is determined. It is shown that, depending on the choice of the boundary charges, one may obtain either the linear or the non-linear superconformal algebra on the boundary. We compare the non-linear version of the asymptotic symmetry algebra with the non-linear coset algebra and find non-trivial agreement in the 't Hooft limit, thus giving strong support for the proposed duality. As a by-product of our analysis we also show that the W_infinity symmetry of the coset theory is broken under the exactly marginal perturbation that preserves the N=4 superconformal algebra.Comment: 26 page

    Higher order semiparametric frequentist inference with the profile sampler

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    We consider higher order frequentist inference for the parametric component of a semiparametric model based on sampling from the posterior profile distribution. The first order validity of this procedure established by Lee, Kosorok and Fine in [J. American Statist. Assoc. 100 (2005) 960--969] is extended to second-order validity in the setting where the infinite-dimensional nuisance parameter achieves the parametric rate. Specifically, we obtain higher order estimates of the maximum profile likelihood estimator and of the efficient Fisher information. Moreover, we prove that an exact frequentist confidence interval for the parametric component at level α\alpha can be estimated by the α\alpha-level credible set from the profile sampler with an error of order OP(n−1)O_P(n^{-1}). Simulation studies are used to assess second-order asymptotic validity of the profile sampler. As far as we are aware, these are the first higher order accuracy results for semiparametric frequentist inference.Comment: Published in at http://dx.doi.org/10.1214/07-AOS523 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

    New line-interactive UPS system with DSP-based active power-line conditioning

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