31,258 research outputs found

    Elastic and plastic analysis of pressure vessel weld lands with mismatch

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    Elastic and plastic analysis of pressure vessel weld lands with mismatc

    Application and sensitivity investigation of Fourier transforms for microwave radiometric inversions

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    Existing microwave radiometer technology now provides a suitable method for remote determination of the ocean surface's absolute brightness temperature. To extract the brightness temperature of the water from the antenna temperature equation, an unstable Fredholm integral equation of the first kind was solved. Fast Fourier Transform techniques were used to invert the integral after it is placed into a cross-correlation form. Application and verification of the methods to a two-dimensional modeling of a laboratory wave tank system were included. The instability of the Fredholm equation was then demonstrated and a restoration procedure was included which smooths the resulting oscillations. With the recent availability and advances of Fast Fourier Transform techniques, the method presented becomes very attractive in the evaluation of large quantities of data. Actual radiometric measurements of sea water are inverted using the restoration method, incorporating the advantages of the Fast Fourier Transform algorithm for computations

    Elastic and plastic stresses at weld sinkages and other discontinuities in pressure vessels

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    Mismatch and weld sinkage problems of pressure vessel geometric discontinuities studied in design graphs and test progra

    Lung lobe torsion in adult and juvenile pugs

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    This cases series of 13 pugs with lung lobe torsion (LLT) is the largest case series of pugs in the literature and the first to compare dogs presenting before and after 12 months of age. Similar to previous case series, the median age of pugs with LLT was 17 months; however six dogs were under 12 months of age (3 of 13 were 11–13 weeks at presentation). There were no differences between the dogs that presented younger or older than 12 months old with respect to sex, neuter status, lung lobe affected, duration and nature of clinical signs, time alive after discharge, and complications. The juvenile onset may suggest that some dogs are inherently at risk of LLT. This is intriguing and important as LLT may not be an intuitive diagnosis in a juvenile brachycephalic animal, and practitioners should be aware of this unusual presentation

    Two-sample Bayesian Nonparametric Hypothesis Testing

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    In this article we describe Bayesian nonparametric procedures for two-sample hypothesis testing. Namely, given two sets of samples y(1)  \mathbf{y}^{\scriptscriptstyle(1)}\;\stackrel{\scriptscriptstyle{iid}}{\s im}  F(1)\;F^{\scriptscriptstyle(1)} and y(2)  \mathbf{y}^{\scriptscriptstyle(2 )}\;\stackrel{\scriptscriptstyle{iid}}{\sim}  F(2)\;F^{\scriptscriptstyle( 2)}, with F(1),F(2)F^{\scriptscriptstyle(1)},F^{\scriptscriptstyle(2)} unknown, we wish to evaluate the evidence for the null hypothesis H0:F(1)F(2)H_0:F^{\scriptscriptstyle(1)}\equiv F^{\scriptscriptstyle(2)} versus the alternative H1:F(1)F(2)H_1:F^{\scriptscriptstyle(1)}\neq F^{\scriptscriptstyle(2)}. Our method is based upon a nonparametric P\'{o}lya tree prior centered either subjectively or using an empirical procedure. We show that the P\'{o}lya tree prior leads to an analytic expression for the marginal likelihood under the two hypotheses and hence an explicit measure of the probability of the null Pr(H0{y(1),y(2)})\mathrm{Pr}(H_0|\{\mathbf {y}^{\scriptscriptstyle(1)},\mathbf{y}^{\scriptscriptstyle(2)}\}\mathbf{)}.Comment: Published at http://dx.doi.org/10.1214/14-BA914 in the Bayesian Analysis (http://projecteuclid.org/euclid.ba) by the International Society of Bayesian Analysis (http://bayesian.org/

    Total focussing method for volumetric imaging in immersion non destructive evaluation

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    This paper describes the use of a 550 (25x22) element 2MHz 2D piezoelectric composite array in immersion mode to image an aluminum test block containing a collection of artificial defects. The defects included a 1mm diameter side-drilled hole, a collection of 1mm slot defects with varying degrees of skew to the normal and a flat bottomed hole. The data collection was carried out using the full matrix capture; a scanning procedure was developed to allow the operation of the large element count array through a conventional 64-channel phased array controller. A 3D TFM algorithm capable of imaging in a dual media environment was implemented in MATLAB for the offline processing the raw scan data. This algorithm facilitates the creation of 3D images of defects while accounting for refraction effects at material boundaries. In each of the test samples interrogated the defects, and their spatial position, are readily identified using TFM. Defect directional information has been characterized using VTFM for defect exhibiting angles up to and including 45o of skew
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