10,278 research outputs found

    Inverse airfoil design procedure using a multigrid Navier-Stokes method

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    The Modified Garabedian McFadden (MGM) design procedure was incorporated into an existing 2-D multigrid Navier-Stokes airfoil analysis method. The resulting design method is an iterative procedure based on a residual correction algorithm and permits the automated design of airfoil sections with prescribed surface pressure distributions. The new design method, Multigrid Modified Garabedian McFadden (MG-MGM), is demonstrated for several different transonic pressure distributions obtained from both symmetric and cambered airfoil shapes. The airfoil profiles generated with the MG-MGM code are compared to the original configurations to assess the capabilities of the inverse design method

    Investigations of electron emission characteristics of low work function surfaces Quarterly report, 28 Sep. - 27 Dec. 1966

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    Coadsorption of cesium and fluorine on tungsten, and analysis of mechanisms leading to decay of field emission current from low work function zirconium/oxygen coated tungsten emitte

    Friction factors for smooth pipe flow

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    Friction factor data from two recent pipe flow experiments are combined to provide a comprehensive picture of the friction factor variation for Reynolds numbers from 10 to 36,000,000

    Volume 2 - Literature review of adsorption on metal surfaces Final report, 1 May 1966 - 2 Jul. 1967

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    Atom and ion desorption energy, chemisorption theory and surface bonds, work functions and potential energy in literature review of adsorption on metal surface

    Tests of the Gravitational Inverse-Square Law below the Dark-Energy Length Scale

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    We conducted three torsion-balance experiments to test the gravitational inverse-square law at separations between 9.53 mm and 55 micrometers, probing distances less than the dark-energy length scale λd=c/ρd485μ\lambda_{\rm d}=\sqrt[4]{\hbar c/\rho_{\rm d}}\approx 85 \mum. We find with 95% confidence that the inverse-square law holds (α1|\alpha| \leq 1) down to a length scale λ=56μ\lambda = 56 \mum and that an extra dimension must have a size R44μR \leq 44 \mum.Comment: 4 pages, 6 figure

    Political attitudes of the young electorate in the 2016 presidential election and parental influences on political identity formation.

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    We examined the political attitudes of college-aged students and the political identities of their parents to better understand the role that both parent-child political socialization and the liberal university environment play in political identity formation. We compared students explicit and implicit political attitudes and examined the relationships of these attitudes to the political identities of their parents. We also explored the uniqueness of two candidates, Bernie Sanders and Donald Trump in the 2016 Presidential election. Our results supported the existing notion of parental influences on political identity formation and revealed that the university environment may not play as large of a role in shifting first and second year university students away from political identities established at home. However, data revealed greater support for the non-traditional candidate in our left-leaning participants, suggesting that factors other than parent influence could be at play in forming the political identities of the youth

    Higher-order unfolding of satellite heterochromatin is a consistent and early event in cell senescence

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    Epigenetic changes to chromatin are thought to be essential to cell senescence, which is key to tumorigenesis and aging. Although many studies focus on heterochromatin gain, this work demonstrates large-scale unraveling of peri/centromeric satellites, which occurs in all models of human and mouse senescence examined. This was not seen in cancer cells, except in a benign senescent tumor in vivo. Senescence-associated distension of satellites (SADS) occurs earlier and more consistently than heterochromatin foci formation, and SADS is not exclusive to either the p16 or p21 pathways. Because Hutchinson Guilford progeria syndrome patient cells do not form excess heterochromatin, the question remained whether or not proliferative arrest in this aging syndrome involved distinct epigenetic mechanisms. Here, we show that SADS provides a unifying event in both progeria and normal senescence. Additionally, SADS represents a novel, cytological-scale unfolding of chromatin, which is not concomitant with change to several canonical histone marks nor a result of DNA hypomethylation. Rather, SADS is likely mediated by changes to higher-order nuclear structural proteins, such as LaminB1

    Magnetic moment non-conservation in magnetohydrodynamic turbulence models

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    The fundamental assumptions of the adiabatic theory do not apply in presence of sharp field gradients as well as in presence of well developed magnetohydrodynamic turbulence. For this reason in such conditions the magnetic moment μ\mu is no longer expected to be constant. This can influence particle acceleration and have considerable implications in many astrophysical problems. Starting with the resonant interaction between ions and a single parallel propagating electromagnetic wave, we derive expressions for the magnetic moment trapping width Δμ\Delta \mu (defined as the half peak-to-peak difference in the particle magnetic moment) and the bounce frequency ωb\omega_b. We perform test-particle simulations to investigate magnetic moment behavior when resonances overlapping occurs and during the interaction of a ring-beam particle distribution with a broad-band slab spectrum. We find that magnetic moment dynamics is strictly related to pitch angle α\alpha for a low level of magnetic fluctuation, δB/B0=(103,102)\delta B/B_0 = (10^{-3}, \, 10^{-2}), where B0B_0 is the constant and uniform background magnetic field. Stochasticity arises for intermediate fluctuation values and its effect on pitch angle is the isotropization of the distribution function f(α)f(\alpha). This is a transient regime during which magnetic moment distribution f(μ)f(\mu) exhibits a characteristic one-sided long tail and starts to be influenced by the onset of spatial parallel diffusion, i.e., the variance grows linearly in time as in normal diffusion. With strong fluctuations f(α)f(\alpha) isotropizes completely, spatial diffusion sets in and f(μ)f(\mu) behavior is closely related to the sampling of the varying magnetic field associated with that spatial diffusion.Comment: 13 pages, 10 figures, submitted to PR
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