21,810 research outputs found

    Russian Cities in Transition: The Impact of Market Forces in the 1990s

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    This paper analyses Russian city growth during the command and transition eras. Our main focus is on understanding the extent to which market forces are replacing command forces, and the resulting changes in Russian city growth patterns. We examine net migration rates for a sample of 171 medium and large cities for the period 1960 through 2002. We conclude that while the declining net migration rate was reversed during the first half of the 1990s, restrictions continued to matter during the early years of transition in the sense that net migration rates were lower in the restricted than in the unrestricted cities. This pattern seemingly came to an end in the late 1990s.http://deepblue.lib.umich.edu/bitstream/2027.42/40083/3/wp697.pd

    Inhomogeneous superconductivity and the "pseudogap state of novel superconductors

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    Novel superconducting compounds such as the high Tc oxides are intrinsically inhomogeneous systems. An inhomogeneous structure is created by doping and the statistical nature of the distribution of dopants. Consequently, the critical temperature is spatially dependent: Tc = Tc (r).Comment: 63 pages text, 13 figures and 1 tabl

    Russian Cities in Transition: The Impact of Market Forces in the 1990s

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    This paper analyses Russian city growth during the command and transition eras. Our main focus is on understanding the extent to which market forces are replacing command forces, and the resulting changes in Russian city growth patterns. We examine net migration rates for a sample of 171 medium and large cities for the period 1960 through 2002. We conclude that while the declining net migration rate was reversed during the first half of the 1990s, restrictions continued to matter during the early years of transition in the sense that net migration rates were lower in the restricted than in the unrestricted cities. This pattern seemingly came to an end in the late 1990s.cities; city growth; migration; Russia; urbanization

    Accurate object reconstruction by statistical moments

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    Statistical moments can offer a powerful means for object description in object sequences. Moments used in this way provide a description of the changing shape of the object with time. Using these descriptions to predict temporal views of the object requires efficient and accurate reconstruction of the object from a limited set of moments, but accurate reconstruction from moments has as yet received only limited attention. We show how we can improve accuracy not only by consideration of formulation, but also by a new adaptive thresholding technique that removes one parameter needed in reconstruction. Both approaches are equally applicable for Legendre and other orthogonal moments to improve accuracy in reconstruction

    Principles and Implementation of Deductive Parsing

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    We present a system for generating parsers based directly on the metaphor of parsing as deduction. Parsing algorithms can be represented directly as deduction systems, and a single deduction engine can interpret such deduction systems so as to implement the corresponding parser. The method generalizes easily to parsers for augmented phrase structure formalisms, such as definite-clause grammars and other logic grammar formalisms, and has been used for rapid prototyping of parsing algorithms for a variety of formalisms including variants of tree-adjoining grammars, categorial grammars, and lexicalized context-free grammars.Comment: 69 pages, includes full Prolog cod

    Parameter estimation for macroscopic pedestrian dynamics models from microscopic data

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    In this paper we develop a framework for parameter estimation in macroscopic pedestrian models using individual trajectories -- microscopic data. We consider a unidirectional flow of pedestrians in a corridor and assume that the velocity decreases with the average density according to the fundamental diagram. Our model is formed from a coupling between a density dependent stochastic differential equation and a nonlinear partial differential equation for the density, and is hence of McKean--Vlasov type. We discuss identifiability of the parameters appearing in the fundamental diagram from trajectories of individuals, and we introduce optimization and Bayesian methods to perform the identification. We analyze the performance of the developed methodologies in various situations, such as for different in- and outflow conditions, for varying numbers of individual trajectories and for differing channel geometries
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