6,248 research outputs found

    On the distribution of αp\alpha p modulo one in imaginary quadratic number fields with class number one

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    We investigate the distribution of αp\alpha p modulo one in imaginary quadratic number fields K⊂C\mathbb{K}\subset\mathbb{C} with class number one, where pp is restricted to prime elements in the ring of integers O=Z[ω]\mathcal{O} = \mathbb{Z}[\omega] of K\mathbb{K}. In analogy to classical work due to R. C. Vaughan, we obtain that the inequality ∥αp∥ω<N(p)−1/8+ϵ\lVert\alpha p\rVert_\omega < \mathrm{N}(p)^{-1/8+\epsilon} is satisfied for infinitely many pp, where ∥ϱ∥ω\lVert\varrho\rVert_\omega measures the distance of ϱ∈C\varrho\in\mathbb{C} to O\mathscr{O} and N(p)\mathrm{N}(p) denotes the norm of pp. The proof is based on Harman's sieve method and employs number field analogues of classical ideas due to Vinogradov. Moreover, we introduce a smoothing which allows us to make conveniently use of the Poisson summation formula.Comment: 36 page

    Analysing the implication of the EU 20-10-20 targets for world vegetable oil production

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    The European Commission proposes a minimum of 10 % biofuels in the total transport fuel use by 2020. The new 10% minimum target in 2020 is combined with the existing regulation, which fixes the target at 5.75% in 2010. This paper will in particular investigates how a full implementation of the 20- 10-20 targets would affect production and trade of oil plants in the EU and its main trade partners on this commodity markets, particularly Malaysia and Indonesia. The global general equilibrium model GLOBE is used to carry out the policy scenarios and to assess the effects on oil palm plantation area in Malaysia and Indonesia. The results show that the increased EU bio-diesel target will not significantly influence the expansion of palm oil production in Indonesia and Malaysia.Crop Production/Industries, International Relations/Trade, Resource /Energy Economics and Policy,

    Spin transport in graphene/transition metal dichalcogenide heterostructures

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    Since its discovery, graphene has been a promising material for spintronics: its low spin-orbit coupling, negligible hyperfine interaction, and high electron mobility are obvious advantages for transporting spin information over long distances. However, such outstanding transport properties also limit the capability to engineer active spintronics, where strong spin-orbit coupling is crucial for creating and manipulating spin currents. To this end, transition metal dichalcogenides, which have larger spin-orbit coupling and good interface matching, appear to be highly complementary materials for enhancing the spin-dependent features of graphene while maintaining its superior charge transport properties. In this review, we present the theoretical framework and the experiments performed to detect and characterize the spin-orbit coupling and spin currents in graphene/transition metal dichalcogenide heterostructures. Specifically, we will concentrate on recent measurements of Hanle precession, weak antilocalization and the spin Hall effect, and provide a comprehensive theoretical description of the interconnection between these phenomena.Comment: 21 pages, 11 figures. This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Nano Letters, copyright\c{opyright}American Chemical Society after peer review. To access the final edited and published work see http://pubs.rsc.org/en/Content/ArticleLanding/2018/CS/C7CS00864

    Fluid-Structure Interaction Simulation of a Coriolis Mass Flowmeter using a Lattice Boltzmann Method

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    In this paper we use a fluid-structure interaction (FSI) approach to simulate a Coriolis mass flowmeter (CMF). The fluid dynamics are calculated by the open source framework OpenLB, based on the lattice Boltzmann method (LBM). For the structural dynamics we employ the open source software Elmer, an implementation of the finite element method (FEM). A staggered coupling approach between the two software packages is presented. The finite element mesh is created by the mesh generator Gmsh to ensure a complete open source workflow. The Eigenmodes of the CMF, which are calculated by modal analysis are compared with measurement data. Using the estimated excitation frequency, a fully coupled, partitioned, FSI simulation is applied to simulate the phase shift of the investigated CMF design. The calculated phaseshift values are in good agreement to the measurement data and verify the suitability of the model to numerically describe the working principle of a CMF
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