1,250 research outputs found

    Exploiting the Design Freedom of RM

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    This paper details how Rapid Manufacturing (RM) can overcome the restrictions imposed by the inherent process limitations of conventional manufacturing techniques and become the enabling technology in fabricating optimal products. A new design methodology capable of exploiting RM’s increased design freedom is therefore needed. Inspired by natural world structures of trees and bones, a multi-objective, genetic algorithm based topology optimisation approach is presented. This combines multiple unit cell structures and varying volume fractions to create a heterogeneous part structure which exhibits a uniform stress distribution.Mechanical Engineerin

    Optimal interlayer hopping and high temperature Bose–Einstein condensation of local pairs in quasi 2D superconductors

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    Both FeSe and cuprate superconductors are quasi 2D materials with high transition temperatures and local fermion pairs. Motivated by such systems, we investigate real space pairing of fermions in an anisotropic lattice model with intersite attraction, V, and strong local Coulomb repulsion, U, leading to a determination of the optimal conditions for superconductivity from Bose–Einstein condensation. Our aim is to gain insight as to why high temperature superconductors tend to be quasi 2D. We make both analytically and numerically exact solutions for two body local pairing applicable to intermediate and strong V. We find that the Bose–Einstein condensation temperature of such local pairs pairs is maximal when hopping between layers is intermediate relative to in-plane hopping, indicating that the quasi 2D nature of unconventional superconductors has an important contribution to their high transition temperatures

    Determining the phonon density of states from specific heat measurements via maximum entropy methods

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    The maximum entropy and reverse Monte Carlo methods are applied to the computation of the phonon density of states (DOS) from heat capacity data. The approach is introduced and the formalism is described. Simulated data are used to test the method, and its sensitivity to noise. Heat capacity measurements from diamond are used to demonstrate the use of the method with experimental data. Comparison between maximum entropy and reverse Monte Carlo results shows that the form of the entropy used here is correct, and that results are stable and reliable. Major features of the DOS are picked out, and acoustic and optical phonons can be treated with the same approach. The treatment set out in this paper provides a cost-effective and reliable method for studies of the phonon properties of materials
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