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Upwelling processes bring nutrient-rich waters from the deep ocean to the surface. Areas of upwelling are often associated with high productivity, offering great economic value in terms of fisheries. The sensitivity of spring/summer-time coastal upwelling systems to climate change has recently received a lot of attention. Several studies have suggested that their intensity may increase in the future while other authors have shown decreasing intensity in their equatorward portions. Yet, recent observations do not show robust evidence of this intensification. The Senegalo-Mauritanian upwelling system (SMUS) located at the southern edge of the north Atlantic system (12°N–20°N) and most active in winter/spring has been largely excluded from these studies. Here, the seasonal cycle of the SMUS and its response to climate change is investigated in the database of the Coupled Models Inter comparison Project Phase 5 (CMIP5). Upwelling magnitude and surface signature are characterized by several sea surface temperature and wind stress indices. We highlight the ability of the climate models to reproduce the system, as well as their biases. The simulations suggest that the intensity of the SMUS winter/spring upwelling will moderately decrease in the future, primarily because of a reduction of the wind forcing linked to a northward shift of Azores anticyclone and a more regional modulation of the low pressures found over Northwest Africa. The implications of such an upwelling reduction on the ecosystems and local communities exploiting them remains very uncertain.

This paper deals the study of the lead-acid behavior and its modelling based on the Kinetic Battery Model. Results of experimental tests are used to realize the analysis and to estimate the model parameters. These last can serve for prediction and estimation of the battery lifetime according to the actual operating conditions.

AbstractMononuclear trivalent lanthanide complexes with formula [Ln(L)(NO3)3] [in which L=4,4‐difluoro‐8‐(2′:2′′;6′′:2′′′‐terpyridin‐4′′‐yl)‐1,3,5,7‐tetramethyl‐2,6‐diethyl‐4‐bora‐3a,4a‐diaza‐s‐indacene (Boditerpy)] are reported for Ln=Yb, Nd, Er, La and Gd. According to the crystal structure of the Yb complex, the lanthanide ion is bound to the terdentate terpyridine and the inner coordination sphere of the nine‐coordinate lanthanide ion is completed by three bidentate nitrate anions. The coordination polyhedron can be described as a distorted tricapped antiprism. The terpyridine chelate is almost planar and tilted by nearly 60° from the indacene subunit. FT‐IR spectra confirm the bidentate binding mode of the nitrate anions for the other complexes. NMR and ES‐MS spectra (through characteristic isotopic patterns) confirm the chemical formulation. The complexes have high molar absorption coefficients in the visible spectral region (65 000 M−1 cm−1 at 529 nm) and display sizeable NIR luminescence (900 to 1600 nm, for Ln=Yb, Nd and Er), upon irradiation through the electronic state of the indacene moiety at 514 nm. Crystal‐field splitting was analysed at low temperature. The quantum yield of the Yb solution (10−4 M) in dichloromethane amounts to 0.31 %, corresponding to a sensitisation efficacy of the ligand of ca. 63 %.

1 Faculty of Science and Technology, University Cheikh Anta Diop, Dakar-Senegal 2 Mining School of Niamey-Niger 3 Ecole Supeieure polytechnique de Daar-Senegal 4 Ecole Polytechnique of Thies, EPT, Thies, Senegal 5 Faculty of Science and Technology, University Cheikh Anta Diop, Dakar-Senegal 6 Ecole Supeieure polytechnique de Daar-Senegal 7 Faculty of Science and Technology, University Cheikh Anta Diop, Dakar-Senegal

Abstract In Senegal, soil is used in construction with a misunderstanding of the thermal and mechanical properties. The lifespan of building considerably depends of the mechanical properties of construction materials used. The thermal properties of construction materials have considerable influence on the energy performance of the building. This work deals with the determination of thermal and mechanical properties of soil bricks stabilized with cement produced by five handicraft manufacturers. For the mechanical characterization, we determine the compressive strength of bricks using a mechanical press. The thermal characterization is to determine thermal capacity and thermal conductivity of bricks by asymmetrical transient Hot Plate method. The results show that vibrated bricks have a compressive strength of about 1.6 MPa and a thermal conductivity of about 0.8 W.m-1.K-1. The compressed bricks have better compression strength of about 2 MPa and a thermal conductivity of about 0.7 W.m-1.K-1.

The theoretical study of chrysanthemin (cyanidin 3-glucoside) as a pigment for TiO2-based dye-sensitized solar cells (DSSCs) was performed with the GAUSSSIAN 09 simulation. The electronic spectra of neutral and anionic chrysanthemin molecules were calculated by density functional theory with B3LYP functional and DGDZVP basis set. A better energy level alignment was found for partially deprotonated molecules of chrysanthemin, with the excited photoelectron having enough energy in order to be transferred to the conduction band of TiO2 semiconductor in DSSCs. In addition, we used the raw aqueous extracts of roselle (Hibiscus sabdariffa) calyces as the source of chrysanthemin and the extracts with various pH values were tested in DSSCs. The extracts and photosensitized semiconductor layers were characterized by UV-Vis spectroscopy, and DSSCs based on raw extracts were characterized by current density-voltage measurements.

A theoretical and experimental study of a conventional boost converter is presented. Based on the real behavior of the components, the conventional boost converter model dealing with both inductive and capacitive losses as well as switching losses is introduced. From this model, the detailed analytical expressions of the voltage gain factor and the conversion efficiency are established taking into account the losses due to parasitic resistances and switching losses. The behavior of the converter is then analyzed by simulating the voltage gain factor and the conversion efficiency as a function of the duty cycle. The converter prototype was manufactured and a set of experimental measurements was made; these measurements made it possible to demonstrate that the proposed theoretical models were reliable for a large range of duty cycle for the boost converter.