Spatial Analysis of the Erosive Hazard of Soils and Natural Risks of Reservoir Siltation

The initial state of several watersheds, in West Africa, is characterized by a socio-ecological vulnerability linked to the water erosion risks. Thus, the Oued Beht watershed (430,728 ha), which is located in Morocco, reveals the extent of impact of soil erosion and water quality degradations. Especially, the consequences of soil loss alter its hydrological behavior in terms of efficiency to produce good water quality and include damages to the functional activities (agricultural and forestry) and structural challenges (lands and dams). This study suggests a methodology, reproducible and generalizable, to assess the water erosion risks. The results show that the erosion process is characterized by the combination of several types of erosion including sheet, rill, and gully. Therefore, the soil erosion is active and visible on more than 3/4 of the Oued Beht watershed, and the spatial analysis evaluates the soil loss which generates a decrease in the storage capacity of El Kansra dam (−3.03 million m3/year). The erosion risk management is evaluated by combining susceptibility maps with an analysis of potential consequences. Moreover, the interactive mode obtained from this work is based on a statistical autocorrelation approach concerning risk factors in order to delimit the areas requiring priority planning (hot spots)

Mesure de température par pyrométrie 2D à bande spectrale et pyrométrie spectrale de métaux chauffés par laser dans un environnement fortement oxydant

La calibration et la validation de deux techniques de mesure de température complémentaires basées toutes les deux sur la pyrométrie optique (pyrométrie 2D monobande et pyrométrie spectrale), utilisables dans le cadre de l'étude des métaux chauffés dans des conditions hautement oxydantes et plus généralement au cours des procédés laser sur des métaux dans la gamme de température 2000-4000 K ont été réalisées. Une bonne correspondance des résultats des deux méthodes est obtenue lorsque l'émissivité de l'objet est connue et varie peu, mais seule la pyrométrie spectrale est performante lors de grandes variations d'émissivité, fournissant à la fois une mesure de température et d'émissivité au cours du procédé. Les incertitudes ont été calculées et représentent respectivement 6 et 3% dans une gamme de 1800 à 4500 K pour la pyrométrie 2D et la pyrométrie spectrale

Potential-flow models for channelled two-dimensional premixed flames around near-circular obstacles

International audienceThe dynamics of two-dimensional thin premixed flames is addressed in the framework of mathematical models where the flow field on either side of the front is piecewise incompressible and vorticity free. Flames confined in channels with asymptotically straight impenetrable walls are considered. Besides a few free propagations along straight channels, attention is focused on flames propagating against high-speed flows and positioned near a round central obstacle or near two symmetric bumps protruding inward. Combining conformal maps and Green's functions, a regularized generalization of Frankel's integro-differential equation for the instantaneous front shape in each configuration is derived and solved numerically. This produces a variety of real looking phenomena: steady fronts symmetric or not, noise-induced subwrinkles, flashback events, and breathing fronts in pulsating flows. Perspectives and open mathematical and physical problems are finally evoked

On-Shell Description of Unsteady Flames

The problem of non-perturbative description of unsteady premixed flames with arbitrary gas expansion is solved in the two-dimensional case. Considering the flame as a surface of discontinuity with arbitrary local burning rate and gas velocity jumps given on it, we show that the front dynamics can be determined without having to solve the flow equations in the bulk. On the basis of the Thomson circulation theorem, an implicit integral representation of the gas velocity downstream is constructed. It is then simplified by a successive stripping of the potential contributions to obtain an explicit expression for the vortex component near the flame front. We prove that the unknown potential component is left bounded and divergence-free by this procedure, and hence can be eliminated using the dispersion relation for its on-shell value (i.e., the value along the flame front). The resulting system of integro-differential equations relates the on-shell fuel velocity and the front position. As limiting cases, these equations contain all theoretical results on flame dynamics established so far, including the linear equation describing the Darrieus-Landau instability of planar flames, and the nonlinear Sivashinsky-Clavin equation for flames with weak gas expansion.Comment: 21 pages, 3 figures; extended discussion of causality, new references adde

Film as a Generative Catalyst for an Empathic University Curriculum

Film screening may enhance the Moroccan university curriculum by providing supplementary educational tools. While the regular educational vision suggests intentional and direct methods, film screening opens promising prospects arising from indirect and deeper emotional perspective. The class composition, in general, imposes certain pedagogical association between professor and students since what matters within the conventional context is the communicative perspective involving the cognitive criteria. What concerns the empathic dimension contrastingly is how to shape a dynamic interaction between emotional and cognitive moods. However, though there is an apparent sort of assimilation and reciprocity between the normative educational class and the empathic one on the ground that the filmmaker takes the place of the university professor while students act as spectators, the question is still open on whether there is any qualitative addition behind film screening that would make a difference

Temperature measurement of laser heated metals in highly oxidizing environment using 2D single-band and spectral pyrometry

Calibration and validation of two temperature measurement techniques both using optical pyrometry, usable in the framework of the study of the heated metals in highly oxidizing environments and more generally during laser processing of materials in the range of 2000-4000 K have been done. The 2D single-band pyrometry technique using a fast camera provides 2D temperature measurement, whereas spectral pyrometry uses a spectrometer analyzing the spectra emitted by a spot on the observed surface, with uncertainties calculated to be, respectively, within ±3 and 6 of the temperature. Both techniques have been used simultaneously for temperature measurement of laser heated V, Nb, Ta, and W rods under argon and to measure the temperature of steel and iron rods during combustion under oxygen. Results obtained with both techniques are very similar and within the error bars of each other when emissivity remains constant. Moreover, spectral pyrometry has proved to be able to provide correct measurement of temperature, even with unexpected variations of the emissivity during the observed process, and to give a relevant value of this emissivity. A validation of a comsol numerical model of the heating cycle of W, Ta, Nb, V rods has been obtained by comparison with the measurement

Temperature measurement of laser heated metals in highly oxidizing environment using 2D single-band and spectral pyrometry

Calibration and validation of two temperature measurement techniques both using optical pyrometry, usable in the framework of the study of the heated metals in highly oxidizing environments and more generally during laser processing of materials in the range of 2000-4000 K have been done. The 2D single-band pyrometry technique using a fast camera provides 2D temperature measurement, whereas spectral pyrometry uses a spectrometer analyzing the spectra emitted by a spot on the observed surface, with uncertainties calculated to be, respectively, within ±3 and 6 of the temperature. Both techniques have been used simultaneously for temperature measurement of laser heated V, Nb, Ta, and W rods under argon and to measure the temperature of steel and iron rods during combustion under oxygen. Results obtained with both techniques are very similar and within the error bars of each other when emissivity remains constant. Moreover, spectral pyrometry has proved to be able to provide correct measurement of temperature, even with unexpected variations of the emissivity during the observed process, and to give a relevant value of this emissivity. A validation of a comsol numerical model of the heating cycle of W, Ta, Nb, V rods has been obtained by comparison with the measurement