107,338 research outputs found

    Bounds on Effective Dynamic Properties of Elastic Composites

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    We present general, computable, improvable, and rigorous bounds for the total energy of a finite heterogeneous volume element or a periodically distributed unit cell of an elastic composite of any known distribution of inhomogeneities of any geometry and elasticity, undergoing a harmonic motion at a fixed frequency or supporting a single-frequency Bloch-form elastic wave of a given wave-vector. These bounds are rigorously valid for \emph{any consistent boundary conditions} that produce in the finite sample or in the unit cell, either a common average strain or a common average momentum. No other restrictions are imposed. We do not assume statistical homogeneity or isotropy. Our approach is based on the Hashin-Shtrikman (1962) bounds in elastostatics, which have been shown to provide strict bounds for the overall elastic moduli commonly defined (or actually measured) using uniform boundary tractions and/or linear boundary displacements; i.e., boundary data corresponding to the overall uniform stress and/or uniform strain conditions. Here we present strict bounds for the dynamic frequency-dependent constitutive parameters of the composite and give explicit expressions for a direct calculation of these bounds

    Wealth, income, earnings and the statistical mechanics of flow systems

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    This paper looks at empirical data from economics regarding wealth, earnings and income, alongside a flow model for an economy based on the general Lotka-Volterra models of Levy & Solomon. The data and modelling suggest that a simple economic system might provide a tractable model for giving an exact statistical mechanical solution for an 'out of equilibrium' flow model. This might also include an exact mathematical definition of a 'dissipative structure' derived from maximum entropy considerations. This paper is primarily a qualitative discussion of how such a mathematical proof might be achieved

    NP coordination in underspecified scope representations

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    Accurately capturing the quantifier scope behaviour of coordinated NPs can be problematic for underspecification systems that define constraints over semantic constructors. We present an extension to a hole-semantics like language that allows a natural representation of coordinated NPs, and a translation from partial scope requirements into constraints on the constructors. We conclude that the efficient decision procedures developed for constraints on semantic constructors enable the possible meanings of sentences containing coordinated NPs to be fully underspecified

    Trauma and Affective Spill

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    A review of Bryoni Trezise, Performing Feeling in Cultures of Memory(Palgrave Macmillan, 2014)
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