Una alternativa a la integral de Riemann

Se trata de un análisis del proceso de aprendizaje matemático desde puntos de vista interdisciplinares donde se pretende que el alumno tenga un desarrollo del proceso matemático de forma paulatina y no se vea forzado a absorber los diversos conceptos de forma simultanea. Finalmente se concluye con la importancia de encontrar una alternativa al sistema de aprendizaje de la integral de Riemann, como el cálculo de superficies a partir de áreas planas o la integral definida.

La integral de Riemann.

La obra trata sobre el estudio de la Integral de Riemann, intentando compatibilizar la sencillez del planteamiento clásico usado en el Bachillerato con las directrices emanadas de la Universidad, que obligan a un planteamiento opuesto al anterior. La estrategia didáctica se ha experimentado en el Instituto de Bachillerato San Juan de la Cruz de Caravaca de la Cruz durante los cursos 1987-88 y 1988-89, tanto en tercero de BUP como en COU. El tema ha sido desarrollado para su lectura directa por los alumnos, por lo que se ha procurado detallar al máximo la exposición.

The Klein-Gordon equation on the half line: a Riemann-Hilbert approach

We solve an initial-boundary problem for the Klein-Gordon equation on the half line using the Riemann-Hilbert approach to solving linear boundary value problems advocated by Fokas. The approach we present can be also used to solve more complicated boundary value problems for this equation, such as problems posed on time-dependent domains. Furthermore, it can be extended to treat integrable nonlinearisations of the Klein-Gordon equation. In this respect, we briefly discuss how our results could motivate a novel treatment of the sine-Gordon equation.

Approximate Riemann solutions of the two-dimensional shallow-water equations

A finite-difference scheme based on flux difference splitting is presented for the solution of the two-dimensional shallow-water equations of ideal fluid flow. A linearised problem, analogous to that of Riemann for gasdynamics, is defined and a scheme, based on numerical characteristic decomposition, is presented for obtaining approximate solutions to the linearised problem. The method of upwind differencing is used for the resulting scalar problems, together with a flux limiter for obtaining a second-order scheme which avoids non-physical, spurious oscillations. An extension to the two-dimensional equations with source terms, is included. The scheme is applied to a dam-break problem with cylindrical symmetry.