508 research outputs found

    A reduced Hsieh–Clough–Tocher element with splitting based on an arbitrary interior point

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    AbstractWe present formulas for a reduced Hsieh–Clough–Tocher (rHCT) element with splitting based on an arbitrary interior point. These formulas use local barycentric coordinates in each of the subtriangles and are not significantly more complicated than formulas for an rHCT element with splitting based on the centroid

    An uncommon fetal retention case: Ruptured ventral hernia in a sheep

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    ΔΕΝ ΔΙΑΤΙΘΕΤΑΙ ΠΕΡΙΛΗΨΗA four-year-old pluriparous sheep was brought to our clinic with the complaints of mild anorexia and a wound on the ventral abdominal area, with part of a dead lamb protruding from this lesion. Clinical examination revealed that there was a fetal retention into the ruptured gravid uterine horn that was trapped within a ventral hernia. At herniorrhaphy after removing the dead fetus, strong connections between the uterine and abdominal wall and chronic scars/necrosed tissues were detected in the wound edges, which revealed the long time lapse between the unnoticed herniation-tearing and surgery. Although many ventral hernia cases have been reported in ovine pregnancies, the high maternal resilience in this ruptured hysterocele case, which had a two-week-old history at minimum, is clinically remarkable

    Composite Polarons in Ferromagnetic Narrow-band Metallic Manganese Oxides

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    A new mechanism is proposed to explain the colossal magnetoresistance and related phenomena. Moving electrons accompanied by Jahn-Teller phonon and spin-wave clouds may form composite polarons in ferromagnetic narrow-band manganites. The ground-state and finite-temperature properties of such composite polarons are studied in the present paper. By using a variational method, it is shown that the energy of the system at zero temperature decreases with the formation of composite polaron; the energy spectrum and effective mass of the composite polaron at finite temperature is found to be strongly renormalized by the temperature and the magnetic field. It is suggested that the composite polaron contribute significantly to the transport and the thermodynamic properties in ferromagnetic narrow-band metallic manganese oxides.Comment: Latex, no figur

    A single hollow beam optical trap for cold atoms

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    We present an optical trap for atoms that we have developed for precision spectroscopy measurements. Cold atoms are captured in a dark region of space inside a blue-detuned hollow laser beam formed by an axicon. We analyze the light potential in a ray optics picture and experimentally demonstrate trapping of laser-cooled metastable xenon atoms.Comment: 12 pages, 8 figure

    Atomic Transport in Dense, Multi-Component Metallic Liquids

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    Pd43Ni10Cu27P0 has been investigated in its equilibrium liquid state with incoherent, inelastic neutron scattering. As compared to simple liquids, liquid PdNiCuP is characterized by a dense packing with a packing fraction above 0.5. The intermediate scattering function exhibits a fast relaxation process that precedes structural relaxation. Structural relaxation obeys a time-temperature superposition that extends over a temperature range of 540K. The mode-coupling theory of the liquid to glass transition (MCT) gives a consistent description of the dynamics which governs the mass transport in liquid PdNiCuP alloys. MCT scaling laws extrapolate to a critical temperature Tc at about 20% below the liquidus temperature. Diffusivities derived from the mean relaxation times compare well with Co diffusivities from recent tracer diffusion measurements and diffsuivities calculated from viscosity via the Stokes-Einstein relation. In contrast to simple metallic liquids, the atomic transport in dense, liquid PdNiCuP is characterized by a drastical slowing down of dynamics on cooling, a q^{-2} dependence of the mean relaxation times at intermediate q and a vanishing isotope effect as a result of a highly collective transport mechanism. At temperatures as high as 2Tc diffusion in liquid PdNiCuP is as fast as in simple liquids at the melting point. However, the difference in the underlying atomic transport mechanism indicates that the diffusion mechanism in liquids is not controlled by the value of the diffusivity but rather by that of the packing fraction

    A robust Logistics-Electric framework for optimal power management of electrified ports under uncertain vessel arrival time

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    \ua9 2024Maritime transport is responsible for producing a considerable amount of environmental pollution due to the reliance of ports and ships on the carbon-based energy sources. With the increasing trend towards port electrification to reduce carbon emissions, the operation of ports will be increasingly relying on the electricity network. This interconnection creates multiple challenges due to the complexity of power flow in the port network, uncertainty of vessel arrival time and fluctuation of power generation of renewable energy sources. These uncertainties can lead to an overload in electricity networks and delays in cargo-handling activities, resulting in increased vessel handling times and environmental emissions. This paper presents a joint logistics-electric framework for optimal operation and power management of electrified ports, considering multiple uncertainties in the arrival time of vessels, network demand, and renewable power generation. An optimal power flow method is developed for a real-life port, with consideration for multiple port logistic assets such as cargo handling equipment, reefers, and renewable energy sources. The proposed model ensures feasible port operation for all uncertainty realisations defined by robust optimisation, while minimising operational costs. Simulation results demonstrate that the probability of a network constraint violation can be as high as 70% for an electrified major UK port if the uncertainty in the port operation is neglected, presenting an unacceptable risk of disruption to port activities. Furthermore, such uncertainty can cause 150% increase in emissions if the ships use their auxiliary engine instead of using shore power. The numerical study shows that such challenges can be handled by a 0.3% increase in the robustness in face of uncertainty, while the cost increase in the worst case does not exceed 4.7%. This shows the effectiveness of the proposed method enhancing robustness against uncertainty at the minimum cost
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