69,008 research outputs found

    Adaptive high-order finite element solution of transient elastohydrodynamic lubrication problems

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    This article presents a new numerical method to solve transient line contact elastohydrodynamic lubrication (EHL) problems. A high-order discontinuous Galerkin (DG) finite element method is used for the spatial discretization, and the standard Crank-Nicolson method is employed to approximate the time derivative. An h-adaptivity method is used for grid adaptation with the time-stepping, and the penalty method is employed to handle the cavitation condition. The roughness model employed here is a simple indentation, which is located on the upper surface. Numerical results are presented comparing the DG method to standard finite difference (FD) techniques. It is shown that micro-EHL features are captured with far fewer degrees of freedom than when using low-order FD methods

    Foodplant Suitabilities and a New Oviposition Record for \u3ci\u3ePapilio Glaucus Canadensis\u3c/i\u3e (Lepidoptera: Papilionidae) in Northern Wisconsin and Michigan

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    (excerpt) The eastern tiger swallowtail butterfly, Papilio glaucus L., is polyphagous, and has been reported to feed upon plant species of at least 13 families (Scudder 1889, Teitz 1972). The Canadian subspecies, P. glaucus canadensis Rothschild and Jordan, is generally believed to be univoltine, to be devoid of the genetic capacity for dark morph females, and to have morphologically distinct characteristics from the southern subspecies, P. glaucus glaucus L

    Hard rod gas with long-range interactions: Exact predictions for hydrodynamic properties of continuum systems from discrete models

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    One-dimensional hard rod gases are explicitly constructed as the limits of discrete systems: exclusion processes involving particles of arbitrary length. Those continuum many-body systems in general do not exhibit the same hydrodynamic properties as the underlying discrete models. Considering as examples a hard rod gas with additional long-range interaction and the generalized asymmetric exclusion process for extended particles (â„“\ell-ASEP), it is shown how a correspondence between continuous and discrete systems must be established instead. This opens up a new possibility to exactly predict the hydrodynamic behaviour of this continuum system under Eulerian scaling by solving its discrete counterpart with analytical or numerical tools. As an illustration, simulations of the totally asymmetric exclusion process (â„“\ell-TASEP) are compared to analytical solutions of the model and applied to the corresponding hard rod gas. The case of short-range interaction is treated separately.Comment: 19 pages, 8 figure

    Representations of the East in the poetry of Byron : a study in culture and identity

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    Includes bibliographical references.Edward Said's notice of 'orientalism' is explored with reference to a cross-section of Byron's narrative verse, taken chronologically. Particular focus is placed on two textual loci, namely, the concepts of 'culture' and 'identity'. These concepts form the basis of a close reading of both the texts themselves, and the manner in which Byron's personal and textual personas shape the narrative and are in turn influenced by their social context. An additional theme of exile is considered, and forms the bridge between a historical analysis of the verse, and current political reality as it is depicted in JM Coetzee's recent novel, Disgrace

    DNA Spools under Tension

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    DNA-spools, structures in which DNA is wrapped and helically coiled onto itself or onto a protein core are ubiquitous in nature. We develop a general theory describing the non-equilibrium behavior of DNA-spools under linear tension. Two puzzling and seemingly unrelated recent experimental findings, the sudden quantized unwrapping of nucleosomes and that of DNA toroidal condensates under tension are theoretically explained and shown to be of the same origin. The study provides new insights into nucleosome and chromatin fiber stability and dynamics

    Mapping vesicle shapes into the phase diagram: A comparison of experiment and theory

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    Phase-contrast microscopy is used to monitor the shapes of micron-scale fluid-phase phospholipid-bilayer vesicles in aqueous solution. At fixed temperature, each vesicle undergoes thermal shape fluctuations. We are able experimentally to characterize the thermal shape ensemble by digitizing the vesicle outline in real time and storing the time-sequence of images. Analysis of this ensemble using the area-difference-elasticity (ADE) model of vesicle shapes allows us to associate (map) each time-sequence to a point in the zero-temperature (shape) phase diagram. Changing the laboratory temperature modifies the control parameters (area, volume, etc.) of each vesicle, so it sweeps out a trajectory across the theoretical phase diagram. It is a nontrivial test of the ADE model to check that these trajectories remain confined to regions of the phase diagram where the corresponding shapes are locally stable. In particular, we study the thermal trajectories of three prolate vesicles which, upon heating, experienced a mechanical instability leading to budding. We verify that the position of the observed instability and the geometry of the budded shape are in reasonable accord with the theoretical predictions. The inability of previous experiments to detect the ``hidden'' control parameters (relaxed area difference and spontaneous curvature) make this the first direct quantitative confrontation between vesicle-shape theory and experiment.Comment: submitted to PRE, LaTeX, 26 pages, 11 ps-fi

    Effect of a 180 deg-extent inlet pressure distortion on the internal flow conditions of a TF30-P-3

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    The measured effects of inlet pressure distortion on the internal flow temperatures and pressures of a TF30-P-3 afterburning turbofan engine are reported. Extensive inner-stage instrumentation combined with stepwise rotation of pressure distortion provided a high degree of circumferential resolution in the data. The steady-state spatial variation in pressures, temperature, and calculated flow velocity and the amplitude and extent of the distorted sectors are given. Data are presented for runs of 77 and 90 percent of low-speed-rotor design speed at pressure distortion levels two-thirds of that required to stall the engine. These data are compared with data taken at clean-inlet conditions. Results indicate that the inlet pressure distortion was quickly attenuated within the compressor, except at the hub of the low-pressure compressor. The distorted sectors also swirled and varied in extent as they passed through the engine. Average velocities within the compressor were about equal to the clean-inlet values
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