44,799 research outputs found

    IBVPs for Scalar Conservation Laws with Time Discontinuous Fluxes

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    The initial boundary value problem for a class of scalar non autonomous conservation laws in one space dimension is proved to be well posed and stable with respect to variations in the flux. Targeting applications to traffic, the regularity assumptions on the flow are extended to a merely L∞\mathbf{L}^{\infty} dependence on time. These results ensure, for instance, the well posedness of a class of vehicular traffic models with time dependent speed limits. A traffic management problem is then shown to admit an optimal solution

    Non Local Conservation Laws in Bounded Domains

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    The well posedness for a class of non local systems of conservation laws in a bounded domain is proved and various stability estimates are provided. This construction is motivated by the modelling of crowd dynamics, which also leads to define a non local operator adapted to the presence of a boundary. Numerical integrations show that the resulting model provides qualitatively reasonable solutions

    Hyperbolic predators vs parabolic preys

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    We present a nonlinear predator-prey system consisting of a nonlocal conservation law for predators coupled with a parabolic equation for preys. The drift term in the predators' equation is a nonlocal function of the prey density, so that the movement of predators can be directed towards region with high prey density. Moreover, Lotka-Volterra type right hand sides describe the feeding. A theorem ensuring existence, uniqueness, continuous dependence of weak solutions and various stability estimates is proved, in any space dimension. Numerical integrations show a few qualitative features of the solutions.Comment: 35 pages, 7 figure

    White Pre-Service Teachers’ Perceptions and their Development of Culturally Relevant Literacy Practices

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    Existent literature purports that providing White teacher candidates with increased exposure to urban schools in order to create culturally competent educators has failed. These findings reflect the notion that teacher ideologies and overall perspectives about working with diverse student groups must be harnessed in a genuine ethic of care and intentionality for students of color. However, few studies have taken the approach of examining the development of culturally relevant pedagogy through context-specific field experiences using content-specific courses. This study examines the perspectives of twenty-five White pre-service teachers from a predominately White, private university regarding their initial perceptions and gained conceptual understanding of culturally relevant pedagogy while teaching reading at an urban middle school. Findings were consistent with previous literature that White pre-service teachers are more interested and comfortable teaching in suburban and private schools and held implicit about teaching in urban schools. However, through the course and urban field experience, pre-service teachers were able to develop teaching behaviors that were deemed culturally relevant(Ladson-Billings, 1995) for teaching reading, and were better prepared to work with students from diverse backgrounds
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