4,442 research outputs found

    A discrete Schrodinger spectral problem and associated evolution equations

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    A recently proposed discrete version of the Schrodinger spectral problem is considered. The whole hierarchy of differential-difference nonlinear evolution equations associated to this spectral problem is derived. It is shown that a discrete version of the KdV, sine-Gordon and Liouville equations are included and that the so called `inverse' class in the hierarchy is local. The whole class of related Darboux and Backlund transformations is also exhibited.Comment: 14 pages, LaTeX2

    Finite element simulation of semi-finishing turning of Electron Beam Melted Ti6Al4V under dry and cryogenic cooling

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    open6noIn the last few years, important step forwards have been made on Finite Element Simulation of machining operations. Wrought Ti6Al4V alloy has been deeply investigated both numerically and experimentally due to its wide application in the industry. Recently, Additive Manufacturing technologies as the Electron Beam Melting and the Direct Melting Laser Sintering are more and more employed in the production of biomedical and aeronautical components made of Ti6Al4V alloy. Fine acicular microstructures are generated by the application of additive manufacturing technologies, affecting the mechanical properties and the machinability. By the consequence, this peculiarity has to be considered in modelling the material behaviour. In this work, a numerical analysis of cylindrical external turning on Electron Beam Melted (EBM) Ti6Al4V alloy is presented. A Johnson-Cook constitutive equation was implemented as a flow stress model and adapted with respect to the wrought Ti6Al4V alloy. The model was calibrated and validated through the cutting forces and temperatures measurements acquired under dry and cryogenic lubricating conditions.openBordin, A; Imbrogno, S.; Rotella, G.; Bruschi, S.; Ghiotti, A.; Umbrello, D.Bordin, Alberto; Imbrogno, S.; Rotella, G.; Bruschi, Stefania; Ghiotti, Andrea; Umbrello, D

    Arthropod monitoring in an automated pasta warehouse

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    Pest monitoring was carried out in an automated pasta warehouse. It is managed with a logistic process and can contain more than 30,000 pallets. Good pest monitoring is difficult in this environment particularly because of the height (more than 20 m). Several sticky traps were placed on the floor under the shelves to monitor the presence of arthropods. Monitoring was done twice, once in March and once in November, each time for two weeks. Results showed the presence of stored-product pests, but also the occurrence of other arthropods.Keywords: Pest monitoring, Stored-product pests, Automatic warehouse, Arthropods, Insects

    Localised projective measurement of a relativistic quantum field in non-inertial frames

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    We propose a scheme to study the effect of motion on measurements of a quantum field carried out by a finite-size detector. We introduce a model of projective detection of a localised field mode in an arbitrary reference frame. We apply it to extract vacuum entanglement by a pair of counter-accelerating detectors and to estimate the Unruh temperature of a single accelerated detector. The introduced method allows us to directly relate the observed effects with the instantaneous proper acceleration of the detector.Comment: 5 pages, 2 figures. v2 Significant increase in the detail level regarding the motivation of the detector mode

    Complete Wetting of Pits and Grooves

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    For one-component volatile fluids governed by dispersion forces an effective interface Hamiltonian, derived from a microscopic density functional theory, is used to study complete wetting of geometrically structured substrates. Also the long range of substrate potentials is explicitly taken into account. Four types of geometrical patterns are considered: (i) one-dimensional periodic arrays of rectangular or parabolic grooves and (ii) two-dimensional lattices of cylindrical or parabolic pits. We present numerical evidence that at the centers of the cavity regions the thicknesses of the adsorbed films obey precisely the same geometrical covariance relation, which has been recently reported for complete cone and wedge filling. However, this covariance does not hold for the laterally averaged wetting film thicknesses. For sufficiently deep cavities with vertical walls and close to liquid-gas phase coexistence in the bulk, the film thicknesses exhibit an effective planar scaling regime, which as function of undersaturation is characterized by a power law with the common critical exponent -1/3 as for a flat substrate, but with the amplitude depending on the geometrical features.Comment: 12 page

    The “Eyeballing” technique : an emerging and alerting trend of alcohol misuse

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    Alternative methods of alcohol consumption have recently emerged among adolescents and young adults, including the alcohol “eyeballing”, which consist in the direct pouring of alcoholic substances on the ocular surface epithelium. In a context of drug and behavioural addictions change, “eyeballing” can be seen as one of the latest and potentially highly risky new trends. We aimed to analyze the existing medical literature as well as online material on this emerging trend of alcohol misusePeer reviewedFinal Published versio

    Active control of blankholder in sheet metal stamping

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    Abstract The continuous demand of shape complexity, product accuracy and extended tools life has led to a widespread use of auxiliary systems in sheet metal stamping. Nevertheless, their performances are often inadequate, making their use a compromise between process efficiency and stability. The paper focuses on a new magneto-rheological actuator design. Both analytical and numerical approaches are developed to evaluate load response and to optimize the magnetic field interaction. A physical prototype according to the design outputs is manufactured and tested at different dynamic conditions. Finally, magnetic force values obtained from FE model and experimental tests are compared
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