Propagation of nonstationary curved and stretched premixed flames with multistep reaction mechanisms

The propagation speed of a thin premixed flame disturbed by an unsteady fluid flow of a larger scale is considered. The flame may also have a general shape but the reaction zone is assumed to be thin compared to the flame thickness. Unlike in preceding publications, the presented asymptotic analysis is performed for a general multistep reaction mechanism and, at the same time, the flame front is curved by the fluid flow. The resulting equations define the propagation speed of disturbed flames in terms of the properties of undisturbed planar flames and the flame stretch. Special attention is paid to the near-equidiffusion limit. In this case, the flame propagation speed is shown to depend on the effective Zeldovich number Z(f) , and the flame stretch. Unlike the conventional Zeldovich number, the effective Zeldovich number is not necessarily linked directly to the activation energies of the reactions. Several examples of determining the effective Zeldovich number for reduced combustion mechanisms are given while, for realistic reactions, the effective Zeldovich number is determined from experiments. Another feature of the present approach is represented by the relatively simple asymptotic technique based on the adaptive generalized curvilinear system of coordinates attached to the flame (i.e., intrinsic disturbed flame equations [IDFE]).

El alumnado extranjero en el sistema educativo espa??ol (1992-2003)

Se analiza el proceso de incorporaci??n de ni??os y ni??as extranjeros al sistema educativo espa??ol desde 1992 hasta 2003, teniendo en cuenta las siguientes variables: curso escolar, regi??n geogr??fica de procedencia del alumnado, comunidad aut??noma, nivel educativo, y titularidad del centro. Se aporta como resultado, un mapa diagn??stico cuantitativo de c??mo se ha configurado en Espa??a la pluriculturalidad del sistema educativo. Por ??ltimo, se ofrece un an??lisis detallado del ??ltimo curso escolar 2002-2003 basado en las mismas variables citadas anteriormente.

Proyecto lector : memoria.

El proyecto está coordinado por el Equipo Psicopedagógico del sector de Navalmoral de la Mata (Cáceres). Ejemplar fotocopiado