18,054 research outputs found

    The impact of a wave farm on large scale sediment transport

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    This study investigates the interactions of waves and tides at a wave farm in the southwest of England, in particular their effects on radiation stress, bottom stress, and consequently on the sediment transport and the coast adjacent to the wave-farm (the Wave Hub). In this study, an integrated complex numerical modelling system is setup at the Wave Hub site and is used to compute the wave and current fields by taking into account the wave-current interaction, as well as the sediment transport. Results show that tidal elevation and tidal currents have a significant effect on the wave height and direction predictions; tidal forcing and wind waves have a significant effect on the bed shear-stress, relevant to sediment transport; waves via radiation stresses have an important effect on the longshore and cross-shore velocity components, particularly during the spring tides. Waves can impact on bottom boundary layer and mixing in the water column. The results highlight the importance of the interactions between waves and tides when modelling coastal morphology with presence of wave energy devices

    Deductive and Analogical Reasoning on a Semantically Embedded Knowledge Graph

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    Representing knowledge as high-dimensional vectors in a continuous semantic vector space can help overcome the brittleness and incompleteness of traditional knowledge bases. We present a method for performing deductive reasoning directly in such a vector space, combining analogy, association, and deduction in a straightforward way at each step in a chain of reasoning, drawing on knowledge from diverse sources and ontologies.Comment: AGI 201

    Phenomenological analysis of the double pion production in nucleon-nucleon collisions up to 2.2 GeV

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    With an effective Lagrangian approach, we analyze several NN \to NN\pi\pi channels by including various resonances with mass up to 1.72 GeV. For the channels with the pion pair of isospin zero, we confirm the dominance of N*(1440)\to N\sigma in the near threshold region. At higher energies and for channels with the final pion pair of isospin one, we find large contributions from N*(1440)\to \Delta\pi, double-Delta, \Delta(1600) \to N*(1440)\pi, \Delta(1600) \to \Delta\pi and \Delta(1620) \to \Delta\pi. There are also sizeable contributions from \Delta \to \Delta\pi, \Delta \to N\pi, N \to \Delta\pi and nucleon pole at energies close to the threshold. We well reproduce the total cross sections up to beam energies of 2.2 GeV except for the pp\to pp\pi^0\pi^0 channel at energies around 1.1 GeV and our results agree with the existing data of differential cross sections of pp \to pp\pi^+\pi^-, pp \to nn\pi^+\pi^+ and pp \to pp\pi^0\pi^0 which are measured at CELSIUS and COSY.Comment: 36 pages, 18 figure