The mediation is based on an essential component called mediator. The main role of the mediator is to reformulate a user query, written in terms of global schema, in queries written in terms of sources schemas. This paper describes an algorithm for reformulation of XQuery queries. The algorithm is based on the principle of logical equivalence, simple and complex unification, to obtain a better reformulation. It takes as parameter the query XQuery, the global schema (written in XMLSchema), mappings GLAV and gives as a result a query written in terms of sources schemas. The results of implementation show the proper functioning of the algorithm.

The aim of this work is to study the global existence of solutions for some coupled systems of reaction diffusion which describe the spread within a population of infectious disease. We consider a triangular matrix diffusion and we show that we can prove global existence of classical solutions for the nonlinearities of weakly exponential growth.

    Nickel based super alloys are promising materials for high temperature structural applications because of their low density. The single grain super alloys are extremely creep resistant at high temperature, due to the fraction of Ni3Al based ’ precipitates coherent with a Ni based  matrix [1, 3]. The cuboids group together and form semi-coherent interfaces after a long annealing at high temperature. The ’ precipitate growths in nickel base super alloys often favor the parallelism of (111) planes between cubic dissimilar crystals [4]. In consequences, a hexagonal network of dislocations, that covers the hetero-interphase, is arranged by accommodation of the angular misfit between two semi coherent crystals ( ). In this work, the magnitude of the distortions is simulated as arising from a trigonal network of subsurface misfit dislocations partly dissociated in Shockley dislocations limiting intrinsic and /or extrinsic stacking faults. The results derived from a previous explicit formulation using double Fourier series [5]. Each harmonic term of the series depends on the anisotropic elastic constants and the thickness of each phase. The program built is in a double precision Fortran language and it shows the magnitude and the aspect of the distortions of the free surfaces when the dissociation change in the hetero-interphase. Also, the program has the advantage to fully apply to hetero-epitaxial systems, whatever is the thickness of the free surfaces.