291 research outputs found

    An analysis of available data on effects of wing-fuselage-tail and wing-nacelle interference on the distribution of the air load among components of airplanes

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    Available information on the effects of wing-fuselage-tail and wing-nacelle interference on the distribution of the air load among components of airplanes is analyzed. The effects of wing and nacelle incidence, horizontal andvertical position of wing and nacelle, fuselage shape, wing section and filleting are considered. Where sufficient data were unavailable to determine the distribution of the air load, the change in lift caused by interference between wing and fuselage was found. This increment is affected to the greatest extent by vertical wing position

    Charts for Determining Preliminary Values of Span-load, Shear, Bending-moment, and Accumulated-torque Distributions of Swept Wings of Various Taper Ratios

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    Contains charts for use in determining preliminary values of the spanwise-load, shear, bending-moment, and accumulated-torque distributions of swept wings. The charts are based on strip theory and include four aerodynamic-load distributions, two section-moment distributions, and two inertia-load distributions. The taper ratios considered cover the range from 1.0 to 0 and the results are applicable to any angle of sweep

    Finite Element Methods for One Dimensional Elliptic Distributed Optimal Control Problems with Pointwise Constraints on the Derivative of the State

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    We investigate C1C^1 finite element methods for one dimensional elliptic distributed optimal control problems with pointwise constraints on the derivative of the state formulated as fourth order variational inequalities for the state variable. For the problem with Dirichlet boundary conditions, we use an existing H52ϵH^{\frac52-\epsilon} regularity result for the optimal state to derive O(h12ϵ)O(h^{\frac12-\epsilon}) convergence for the approximation of the optimal state in the H2H^2 norm. For the problem with mixed Dirichlet and Neumann boundary conditions, we show that the optimal state belongs to H3H^3 under appropriate assumptions on the data and obtain O(h)O(h) convergence for the approximation of the optimal state in the H2H^2 norm

    A One Dimensional Elliptic Distributed Optimal Control Problem with Pointwise Derivative Constraints

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    We consider a one dimensional elliptic distributed optimal control problem with pointwise constraints on the derivative of the state. By exploiting the variational inequality satisfied by the derivative of the optimal state, we obtain higher regularity for the optimal state under appropriate assumptions on the data. We also solve the optimal control problem as a fourth order variational inequality by a C1C^1 finite element method, and present the error analysis together with numerical results

    Влияние облучения импульсным электронным пучком на структуру и свойства сплава Ti-6AI-4V

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    Объектом исследования являются образцы титанового сплава Ti-6Al-4V. Цель работы: Экспериментальное исследование влияния радиационного воздействия на структурно-фазовое состояние и механические свойства титанового сплава Ti-6Al-4V. Сплав Ti-6Al-4V представляет собой ?-? титановый сплав с высокой прочностью, низким весовым отношением и отличной коррозионной стойкостью. Это один из наиболее часто используемых титановых сплавов, который подходит для широкого спектра применений, требующих низкой плотности и отличной коррозионной стойкости, таких как аэрокосмические и биомеханические применения.The object of the study are samples of titanium alloy Ti-6Al-4V. Objective: An experimental study of the effect of radiation on the structural phase state and mechanical properties of the titanium alloy Ti-6Al-4V. Ti-6Al-4V is an ?-? titanium alloy with high strength, low weight ratio and excellent corrosion resistance. It is one of the most commonly used titanium alloys, which is suitable for a wide range of applications requiring low density and excellent corrosion resistance, such as aerospace and biomechanical applications

    Metropolitan Briefing Book, 2007

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    The Institute of Portland Metropolitan Studies (IMS) was created to connect the resources of higher education to the needs of the six-county, bit-state Portland-Vancouver metropolitan area (Clackamas, Clark, Columbia, Multnomah, Washington, and Yamhill Counties). In this spirit, we offer our 2007 Metropolitan Briefing Book. Our theme is regional variety. Variety has been touted as the very spice of life (William Cowper) and as the mother of enjoyment (Vivan Grey). Our region enjoys a good deal of variety--in its landscapes, in its economy, and in its people, their cultures, and their attitudes. These differences are important to local vitality and beauty. But while we generally view this variety as positive, we also worry about equity. Although we promote regional thought and action, we must understand that each community experiences the problems facing us in a slightly different way and often with significantly different resources

    Optical Coherence Tomography in Parkinsonian Syndromes

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    BACKGROUND/OBJECTIVE: Parkinson's disease (PD) and the atypical parkinsonian syndromes multiple system atrophy (MSA), progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS) are movement disorders associated with degeneration of the central nervous system. Degeneration of the retina has not been systematically compared in these diseases. METHODS: This cross-sectional study used spectral-domain optical coherence tomography with manual segmentation to measure the peripapillar nerve fiber layer, the macular thickness, and the thickness of all retinal layers in foveal scans of 40 patients with PD, 19 with MSA, 10 with CBS, 15 with PSP, and 35 age- and sex-matched controls. RESULTS: The mean paramacular thickness and volume were reduced in PSP while the mean RNFL did not differ significantly between groups. In PSP patients, the complex of retinal ganglion cell- and inner plexiform layer and the outer nuclear layer was reduced. In PD, the inner nuclear layer was thicker than in controls, MSA and PSP. Using the ratio between the outer nuclear layer and the outer plexiform layer with a cut-off at 3.1 and the additional constraint that the inner nuclear layer be under 46 µm, we were able to differentiate PSP from PD in our patient sample with a sensitivity of 96% and a specificity of 70%. CONCLUSION: Different parkinsonian syndromes are associated with distinct changes in retinal morphology. These findings may serve to facilitate the differential diagnosis of parkinsonian syndromes and give insight into the degenerative processes of patients with atypical parkinsonian syndromes

    Spectrum and Inoculum Size Effect of a Rapid Antigen Detection Test for Group A Streptococcus in Children with Pharyngitis

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    BACKGROUND: The stability of the accuracy of a diagnostic test is critical to whether clinicians can rely on its result. We aimed to assess whether the performance of a rapid antigen detection test (RADT) for group A streptococcus (GAS) is affected by the clinical spectrum and/or bacterial inoculum size. METHODS: Throat swabs were collected from 785 children with pharyngitis in an office-based, prospective, multicenter study (2009-2010). We analysed the effect of clinical spectrum (i.e., the McIsaac score and its components) and inoculum size (light or heavy GAS growth) on the accuracy (sensitivity, specificity, likelihood ratios and predictive values) of a RADT, with laboratory throat culture as the reference test. We also evaluated the accuracy of a McIsaac-score-based decision rule. RESULTS: GAS prevalence was 36% (95CI: 33%-40%). The inoculum was heavy for 85% of cases (81%-89%). We found a significant spectrum effect on sensitivity, specificity, likelihood ratios and positive predictive value (p<0.05) but not negative predictive value, which was stable at about 92%. RADT sensitivity was greater for children with heavy than light inoculum (95% vs. 40%, p<0.001). After stratification by inoculum size, the spectrum effect on RADT sensitivity was significant only in patients with light inoculum, on univariate and multivariate analysis. The McIsaac-score-based decision rule had 99% (97%-100%) sensitivity and 52% (48%-57%) specificity. CONCLUSIONS: Variations in RADT sensitivity only occur in patients with light inocula. Because the spectrum effect does not affect the negative predictive value of the test, clinicians who want to rule out GAS can rely on negative RADT results regardless of clinical features if they accept that about 10% of children with negative RADT results will have a positive throat culture. However, such a policy is more acceptable in populations with very low incidence of complications of GAS infection
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