6,275 research outputs found

    The semidiscrete Galerkin finite element modeling of compressible viscous flow past an airfoil

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    The primary project was the numerical simulation, by a finite element/finite difference method, of the viscous flow about an airfoil. The secondary project involved the numerical simulation of the three-dimensional separated and vortex-dominated flow about a hemispherically capped cylinder in the transonic regime. Preliminary calculations were started for the hemisphere-cylinder at 0 and 5 degree angle of attack. The solution of the flow field about airfoils and wings is required to determine the important parameters of lift, moment, and drag. Viscous effects must be accounted for if the drag is to be accurately calculated. At present there are basically two approaches to the numerical simulation of the flow field, the use of fully viscous models and the inviscid/viscous models. The fully viscous models require the solution of an approximation of the Navier-Stokes equations and therefore should simulate most of the physical mechanisms. A fast, accurate, and computationally efficient inviscid flow solver was recently developed by Hartwich. It is thought that Hartwich's program coupled to a fast, accurate, and computationally efficient boundary layer code, will make an excellent tool for airfoil design. The purpose of the primary project was to develop a compressible boundary layer code using the semidiscrete Galerkin finite element method. The numerical scheme employed used the combination of a Dorodnitsyn formulation of the boundary layer equations, with a finite difference/finite element procedure (semidiscrete Galerkin method), in the solution of the compressible two-dimensional boundary layer equations. A laminar compressible boundary layer code was developed and tested for a NACA 0012 airfoil at a Mach number of 0.5, a Reynolds number of 5000, and zero angle of attack. At present the boundary layer program solves up to, but not beyond, separation

    The use of artificial neural networks in experimental data acquisition and aerodynamic design

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    It is proposed that an artificial neural network be used to construct an intelligent data acquisition system. The artificial neural networks (ANN) model has a potential for replacing traditional procedures as well as for use in computational fluid dynamics validation. Potential advantages of the ANN model are listed. As a proof of concept, the author modeled a NACA 0012 airfoil at specific conditions, using the neural network simulator NETS, developed by James Baffes of the NASA Johnson Space Center. The neural network predictions were compared to the actual data. It is concluded that artificial neural networks can provide an elegant and valuable class of mathematical tools for data analysis

    WISDOM: history and early demise - was it inevitable?

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    In 1989, the UK Medical Research Council (MRC) agreed that, if feasible, a randomized controlled trial to assess the long-term risks and benefits of hormone replacement therapy (HRT) was a priority. Feasibility work began in 1990 and demonstrated that a large-scale multicenter trial was possible. An application for funding for a main trial was submitted to MRC in 1993 and, after extensive review, funding was released in late 1996. Set-up work for the trial - the Women's International Study of long Duration Oestrogen after Menopause (WISDOM) - began in 1997 with recruitment in 1999. In October 2002, following the early discontinuation of one arm of the US Women's Health Initiative HRT trial, the MRC decided to stop the WISDOM trial. This article, by the principal UK investigators of WISDOM, sets out the background and history of the trial

    Block Motion Changes in Japan Triggered by the 2011 Great Tohoku Earthquake

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    Plate motions are governed by equilibrium between basal and edge forces. Great earthquakes may induce differential static stress changes across tectonic plates, enabling a new equilibrium state. Here we consider the torque balance for idealized circular plates and find a simple scalar relationship for changes in relative plate speed as a function of its size, upper mantle viscosity, and coseismic stress changes. Applied to Japan, the 2011 MW=9.0\mathrm{M}_{\mathrm{W}}=9.0 Tohoku earthquake generated coseismic stresses of 102−10510^2-10^5~Pa that could have induced changes in motion of small (radius ∼100\sim100~km) crustal blocks within Honshu. Analysis of time-dependent GPS velocities, with corrections for earthquake cycle effects, reveals that plate speeds may have changed by up to ∼3\sim3 mm/yr between ∼3.75\sim3.75-year epochs bracketing this earthquake, consistent with an upper mantle viscosity of ∼5×1018\sim 5\times10^{18}Pa⋅\cdots, suggesting that great earthquakes may modulate motions of proximal crustal blocks at frequencies as high as 10−810^-8~Hz

    Semiochemicals in merino ewes : field effects and chemical identification

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    Washburn extraction and width of the IUE point spread function

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    The Washburn Extraction Routine for low dispersion IUE spectra was reviewed. The shape of the point spread function (PSF) in low dispersion spectra is sufficiently well described by a gaussian function. The PSF is in large and small aperture essentially identical and values of sigma are presented. Several advantages of the extraction routine are mentioned

    The History of Capital Appeals in Massachusetts

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    Symposium: Toward A Model Death Penalty Code: The Massachusetts Governor\u27s Council Report

    Are tiled display walls needed for astronomy?

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    Clustering commodity displays into a Tiled Display Wall (TDW) provides a cost-effective way to create an extremely high resolution display, capable of approaching the image sizes now gen- erated by modern astronomical instruments. Astronomers face the challenge of inspecting single large images, many similar images simultaneously, and heterogeneous but related content. Many research institutions have constructed TDWs on the basis that they will improve the scientific outcomes of astronomical imagery. We test this concept by presenting sample images to astronomers and non- astronomers using a standard desktop display (SDD) and a TDW. These samples include standard English words, wide field galaxy surveys and nebulae mosaics from the Hubble telescope. These experiments show that TDWs provide a better environment for searching for small targets in large images than SDDs. It also shows that astronomers tend to be better at searching images for targets than non-astronomers, both groups are generally better when employing physical navigation as opposed to virtual navigation, and that the combination of two non-astronomers using a TDW rivals the experience of a single astronomer. However, there is also a large distribution in aptitude amongst the participants and the nature of the content also plays a significant role is success.Comment: 19 pages, 15 figures, accepted for publication in PASA (Publications of the Astronomical Society of Australia

    The History of Capital Appeals in Massachusetts

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    Symposium: Toward A Model Death Penalty Code: The Massachusetts Governor\u27s Council Report

    The reliability of the swimming ergometer in obtaining VOâ‚‚ max of male and female age-group swimmers

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    This study was designed to test the reliability of the swimming ergonometer in obtaining VO2 max of male and female age-group swimmers
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