Journal of Next-Generation Research 5.0
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Satellite-based estimates of surface water dynamics in the Congo River Basin
No full textInternational audienceIn the Congo River Basin (CRB), due to the lack of contemporary in situ observations, there is a limited understanding of the large-scale variability of its present-day hydrologic components and their link with climate. In this context, remote sensing observations provide a unique opportunity to better characterize those dynamics. Analyzing the Global Inundation Extent Multi-Satellite (GIEMS) time series, we first show that surface water extent (SWE) exhibits marked seasonal patterns, well distributed along the major rivers and their tributaries, and with two annual maxima located: i) in the lakes region of the Lwalaba sub-basin and ii) in the “Cuvette Centrale”, including Tumba and Mai-Ndombe Lakes. At an interannual time scale, we show that SWE variability is influenced by ENSO and the Indian Ocean dipole events. We then estimate water level maps and surface water storage (SWS) in floodplains, lakes, rivers and wetlands of the CRB, over the period 2003-2007, using a multi-satellite approach, which combines the GIEMS dataset with the water level measurements derived from the ENVISAT altimeter heights. The mean annual variation in SWS in the CRB is 81±24 km3 and contributes to 19±5 % of the annual variations of GRACE-derived terrestrial water storage (33±7 % in the Middle Congo). It represents also ~6±2 % of the annual water volume that flows from the Congo River into the Atlantic Ocean
Penalization model for navier-stokes-darcy equation with application to porosity-oriented topology optimization
No full textaccepted to Mathematical Models and Methods in Applied Sciences (M3AS)International audienceTopology optimization for fluid flow aims at finding the location of a porous medium minimizing a cost functional under constraints given by the Navier-Stokes equations. The location of the porous media is usually taken into account by adding a penalization term αu, where α is a kinematic viscosity divided by a permeability and u is the velocity of the fluid. The fluid part is obtained when α = 0 while the porous (solid) part is defined for large enough α since this formally yields u = 0. The main drawback of this method is that only solid that does not let the fluid to enter, that is perfect solid, can be considered. In this paper, we propose to use the porosity of the media as optimization parameter hence to minimize some cost function by finding the location of a porous media. The latter is taken into account through a singular perturbation of the Navier-Stokes equations for which we prove that its weak-limit corresponds to an interface fluid-porous medium problem modeled by the Navier-Stokes-Darcy equations. This model is then used as constraint for a topology optimization problem. We give necessary condition for such problem to have at least an optimal solution and derive first order necessary optimality condition. This paper ends with some numerical simulations, for Stokes flow, to show the interest of this approach
Finite Element Modelling design and optimization of Love Wave mesoporous tranducers for biochemical detection in liquid medium
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Acoustic wave sensors for biochemical sensing. Perspectives for in situ measurements in amazon river
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CJUE, (9ème ch.), 25 janvier 2018, aff. C-314/16, Commission contre République tchèque
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Exploitation de l’énergie des mers et adaptation aux changements climatiques dans la zone sud-ouest de l’océan Indien
No full textInternational audienceAt the time of extreme climatic phenomena, it seems that companies (particularly of the energy sector) have to take account of the risks associated with the use of fossil energy and the issues connected to the greenhouse gases emissions. The reading of the business law reveals that this one establishes according to the situation of the company a tool of adaptation to the climate change or a brake in the prevention of the risk resulting from this change. Hardly of this current situation, according to a topdown approach, a « climate company law » should be created. It will impose to revisit the notion of business purpose, to think principles and to draw the new forms of the climatic company, likely to propose ways for discussion, from the bottom up, in view of the skills of the overseas territories (sustainable development and social and solidarity economy).À l’heure des phénomènes climatiques extrêmes mais aussi tendanciels, il apparaît que les entreprises particulièrement du secteur énergétique doivent tenir compte des risques liés à l’exploitation d’énergies fossiles et des enjeux liés à l’émission des gaz à effet de serre. La lecture du droit de l’entreprise révèle que celui-ci constitue, selon la situation de celle-ci, un outil d’adaptation au changement climatique ou un frein dans la prévention du risque résultant de ce changement. Fort de cet état des lieux, il conviendra selon une démarche descendante de construire un « droit climatique » de l’entreprise, ce qui impose de revisiter la notion d’objet social, de penser les principes applicables et dessiner les nouvelles formes que l’entreprise climatique peut emprunter, de nature à favoriser des propositions d’actions de bas en haut au regard des pouvoirs qui sont conférés aux collectivités territoriales ultramarines en matière de développement durable et de développement de l’économie sociale et solidaire