567 research outputs found

    Probabilistic methods for the incompressible navier-stokes equations with space periodic conditions

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    We propose and study a number of layer methods for Navier-Stokes equations (NSEs) with spatial periodic boundary conditions. The methods are constructed using probabilistic representations of solutions to NSEs and exploiting ideas of the weak sense numerical integration of stochastic differential equations. Despite their probabilistic nature, the layer methods are nevertheless deterministic. © ?Applied Probability Trust 2013

    On alternative mixed integer programming formulations and LP-based heuristics for lot-sizing with setup times

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    We address the multi-item, capacitated lot-sizing problem (CLSP) encountered in environments where demand is dynamic and to be met on time. Items compete for a limited capacity resource, which requires a setup for each lot of items to be produced causing unproductive time but no direct costs. The problem belongs to a class of problems that are difcult to solve. Even the feasibility problem becomes combinatorial when setup times are considered. This difculty in reaching optimality and the practical relevance of CLSP make it important to design and analyse heuristics to nd good solutions that can be implemented in practice. We consider certain mixed integer programming formulations of the problem and develop heuristics including a curtailed branch and bound, for rounding the setup variables in the LP solution of the tighter formulations. We report our computational results for a class of instances taken from literature

    Leray-Volevich conditions for systems of abstract evolution equations of Nirenberg/Nishida type

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    Let us consider the following Cauchy problem for a linear differential equation of first order with analytic coefficients and data in a neighbourhood of the origin: ..

    A Pohozaev identity and critical exponents of some complex Hessian equations

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    In this note, we prove some non-existence results for Dirichlet problems of complex Hessian equations. The non-existence results are proved using the Pohozaev method. We also prove existence results for radially symmetric solutions. The main difference of the complex case with the real case is that we don't know if a priori radially symmetric property holds in the complex case.Comment: 14 pages. Comments are welcom

    On the electron to proton mass ratio and the proton structure

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    We derive an expression for the electron to nucleon mass ratio from a reinterpreted lattice gauge theory Hamiltonian to describe interior baryon dynamics. We use the classical electron radius as our fundamental length scale. Based on expansions on trigonometric Slater determinants for a neutral state a specific numerical result is found to be less than three percent off the experimental value for the neutron. Via the exterior derivative on the Lie group configuration space u(3) we derive approximate parameter free parton distribution functions that compare rather well with those for the u and d valence quarks of the proton.Comment: 5 pages, 4 figure

    Study on the vee-block refractometer

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    The vee block (Hilger-Chance) refractometer is to be preferred jn the optical shop because of its good precision, because it measures the bulk and not the skin refractive index, and for the little work needed in the preparation of the sample. The latter is its most important feature. (P&aacute;rrafo extra&iacute;do a modo de resumen)</em
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