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The Atlas cedar (Cedrus atlantica) is an emblematic species of Morocco, classified by the International Union for the Conservation of Nature (IUCN) in the red list of endangered species. Determining its potential area under current climatic conditions is an essential step in planning and ensuring its conservation. In this paper, we applied the maximum-entropy algorithm (MaxEnt) to predict the current and potential distribution of the Atlas cedar in order to provide a basis for its conservation. The adjusted model had an excellent predictive quality (AUC = 0.967). The most significant variables influencing the distribution of Atlas cedar, under current climatic conditions, are the precipitation in the driest quarter, precipitation in the driest month, average annual temperature and relative humidity. The model developed made it possible to establish the first map of the suitable potential area of the Atlas cedar in Morocco. The results obtained will guide managers to identify favorable sites for the rehabilitation of the Atlas cedar threatened with extinction. [ABSTRACT FROM AUTHOR]

Abstract: A granular structure is an aggregation of grains whose sizes are characterized by a given distribution. A sample of this kind of structure is often modeled by a rectangle filled with disks in two dimensions or a parallelepiped containing spherical balls in three dimensions. Therefore, the geometrical modeling of such a structure consists in determining a “dense” repartition of disjoint disks (or spherical balls) with respect to the specified size distribution. In this paper, a new sphere packing algorithm based on an advancing-front approach, commonly used in meshing methods, is proposed. Significant improvements in computing time and density have been obtained comparing to existing methods. In addition, we show that the generated circular grains can be transformed into polygonal (polyhedral) cells generally observed in reality. An example of a metallic nanostructure model is presented. To cite this article: P. Laug et al., C. R. Mecanique 336 (2008). [Copyright &y& Elsevier]

Abstract: The bi-potential method has been successfully applied for the modeling of frictional contact problems in static cases. This paper presents the application of this method for dynamic analysis of impact problems with multiple deformable bodies. A first order algorithm is applied for numerical integration of the time-discretized equation of motion. The numerical results show clearly the physical energy dissipation introduced by frictional effects between the solids in contact. To cite this article: B. Magnain et al., C. R. Mecanique 333 (2005). [Copyright &y& Elsevier]

This paper presents a study devoted to the composite fabric shaping simulation in finite strain analysis. We introduce a new geometrical approach based on the fishnet method for which the deformation of a fabric mesh element consists in a pure trellis effect. Such a fabric mesh element is then defined by a curved quadrilateral whose edges are geodesic lines with the same length plotted onto the surface to drape. Given three vertices of the fabric mesh element on the surface, we propose an optimization algorithm to define the fourth vertex of the fabric mesh element. This algorithm allows us to drape the surface using an advancing front approach from the data of an initial impact point between the fabric and the surface and the initial fibre directions at this point. A numerical draping simulation example using this approach is given. To cite this article: H. Borouchaki, A. Cherouat, C. R. Mecanique 331 (2003). [Copyright &y& Elsevier]