A multiscale method applied to shallow water flow

A flux-limited second order scheme with the C-property is used to solve the one dimensional or two dimensional Saint-Venant system for shallow water flows with non-flat bottom and friction terms, as is introduced in [7] G. Haro, Numerical simulation of shallow water equations amd some physical models in image processing. Ph.D.Thesis, Departament of Technologies, Universitat Pompeu Fabra, Barcelona, 2005. High resolution at low cost can be obtained by applying a point-value multiresolution transform [2, 3, 9] in order to detect regions with singularities. The above method is applied in these regions, while a cheap polynomial interpolation is used in the smooth zones, thus lowering the computational cost

The PCHIP subdivision scheme

In this paper we propose and analyze a nonlinear subdivision scheme based on the monotononicity-preserving third order Hermite-type interpolatory technique implemented in the PCHIP package in Matlab. We prove the convergence and the stability of the PCHIP nonlinear subdivision process by employing a novel technique based on the study of the generalized Jacobian of the first difference scheme.MTM2011-2274

A family of non-oscillatory 6-point interpolatory subdivision schemes

In this paper we propose and analyze a new family of nonlinear subdivision schemes which can be considered non-oscillatory versions of the 6-point Deslauries-Dubuc (DD) interpolatory scheme, just as the Power p schemes are considered nonlinear non-oscillatory versions of the 4-point DD interpolatory scheme. Their design principle may be related to that of the Power p schemes and it is based on a weighted analog of the Power p mean. We prove that the new schemes reproduce exactly polynomials of degree three and stay ’close’ to the 6-point DD scheme in smooth regions. In addition, we prove that the first and second difference schemes are well defined for each member of the family, which allows us to give a simple proof of the uniform convergence of these schemes and also to study their stability as in [19, 22]. However our theoretical study of stability is not conclusive and we perform a series of numerical experiments that seem to point out that only a few members of the new family of schemes are stable. On the other hand, extensive numerical testing reveals that, for smooth data, the approximation order and the regularity of the limit function may be similar to that of the 6-point DD scheme and larger than what is obtained with the Power p schemes

Operadores de reconstrucción y esquemas de subdivisión asociados

Los esquemas de subdivisión son unas herramientas muy usadas en el diseño de curvas y superficies, y tienen también relación con otras aplicaciones interesantes en tratamiento digital de imágenes o en la resolución de ecuaciones diferenciales. Estos esquemas están basados en un conjunto de reglas, las cuales aplicadas recursivamente permiten un refinamiento sucesivo de un conjunto inicial de puntos llamado puntos de control. Una propiedad importante a verificar en estos esquemas es la de preservación de la convexidad y de la monotonía. Una manera de abordar estas cuestiones se basa en la estrecha relación entre esquemas de subdivisión y operadores de reconstrucción. Estos operadores de reconstrucción conectan datos discretos con un cierto espacio funcional, que dependerá de las aplicaciones en concreto. Nuestro objetivo es presentar ciertos operadores de reconstrucción y sus esquemas de subdivisión asociados, verificando si conservan la convexidad y la monotonía

A family of non-oscillatory 6-point interpolatory subdivision schemes

In this paper we propose and analyze a new family of nonlinear subdivision schemes which can be considered non-oscillatory versions of the 6-point Deslauries-Dubuc (DD) interpolatory scheme, just as the Power p schemes are considered nonlinear non-oscillatory versions of the 4-point DD interpolatory scheme. Their design principle may be related to that of the Power p schemes and it is based on a weighted analog of the Power p mean. We prove that the new schemes reproduce exactly polynomials of degree three and stay ’close’ to the 6-point DD scheme in smooth regions. In addition, we prove that the first and second difference schemes are well defined for each member of the family, which allows us to give a simple proof of the uniform convergence of these schemes and also to study their stability as in [19, 22]. However our theoretical study of stability is not conclusive and we perform a series of numerical experiments that seem to point out that only a few members of the new family of schemes are stable. On the other hand, extensive numerical testing reveals that, for smooth data, the approximation order and the regularity of the limit function may be similar to that of the 6-point DD scheme and larger than what is obtained with the Power p schemes

Materials per Matemàtiques II Grau en Química

Material utilitzat per els alumnes de la assignatura de Matemàtiques II del Grau de Química. Conté les diapositives corresponents als temes: Probabilitat, Variables aleatòries, Intervals de confiança, Contrast d'hipòtesis, Regressió, Interpolació polinòmica i Integració numèrica (funcions i equacions diferencials)Material used by students in the subject of Mathematics II of Degree in Chemistry. Contains the slides for the topics: Probability, Random Variables, confidence intervals, hypothesis testing, regression, polynomial interpolation and numerical integration (functions and differential equations)Material docent programat mitjançant l'ajut del Servei de Política Lingüística de la Universitat de València