HAL Portal UPPA (University of Pau and the Pays de l'Adour)
Not a member yet
42255 research outputs found
Sort by
discrete de-Rham complex involving a discontinuous finite element space for velocities: the case of periodic straight triangular and Cartesian meshes
No full textInternational audienceThe aim of this article is to derive discontinuous finite elements vector spaces which can be put in a discrete de-Rham complex for which an harmonic gap property may be proven. First, discontinuous finite element spaces inspired by classical Nédélec or Raviart-Thomas conforming space are considered, and we prove that by relaxing the normal or tangential constraint, discontinuous spaces ensuring the harmonic gap property can be built. Then the triangular case is addressed, for which we prove that such a property holds for the classical discontinuous finite element space for vectors. On Cartesian meshes, this result does not hold for the classical discontinuous finite element space for vectors. We then show how to use the de-Rham complex found for triangular meshes for enriching the finite element space on Cartesian meshes in order to recover a de-Rham complex, on which the same harmonic gap property is proven
Water Management: Tensions, Risks, and Legislation. An Articulating Socio-Environmental Perspective in the Andean Region: Late Nineteenth Century and First Half of the Twentieth Century
No full textInternational audienc
Determining the natal origin of the reintroduced allis shad (Alosa alosa) in the Rhine River using otolith microchemistry
No full textInternational audienceLocally extinct since the 1960s, the anadromous allis shad ( Alosa alosa ) was reintroduced into the Rhine system through a restocking programme beginning in 2007. The population is now showing positive signs of recovery, with natural reproduction occurring for several years and a decreasing proportion of stocked fish. These findings suggest the future establishment of a self-sustaining population. Our study aimed to identify the spawning sites in the Rhine system. We conducted a tank experiment and kept shad larvae in water from four sub-catchments of the Rhine system. We analysed trace substance concentrations in water samples and the microchemical composition of otoliths from reared larvae. Using a random forest model, we were able to correctly attribute the larvae to the sub-catchment where they were raised based on elemental/ratio (Sr/Ca) and strontium isotopes ( 87 Sr/ 86 Sr). From the 66 allis shad caught in the Rhine system between 2017 and 2020, seven individuals (11%) were identified as being stocked. Of the 59 remaining individuals that came from natural reproduction, 37 were attributed to the Rhine, 7 to the Neckar and 4 to the Lippe sub-catchments with high certainty. We also observed allis shads dispersed in adjacent catchment areas and a homing behaviour. A total of 27% of the adults ( n = 9) and 8% of the juveniles ( n = 2) were assigned to any of the four sub-catchments included in our model, suggesting the need to expand the model and include additional sub-catchments to cover all spawning sites in the Rhine system and adjacent catchments
Microbiological and Geochemical Perspectives on Sustainable Dihydrogen Storage in Deep Aquifers
No full textInternational audienceThe successful integration of dihydrogen (H2) as an energy vector relies on effective seasonal storage in underground facilities like deep aquifers. However, the viability of this storage remains uncertain due to the unclear behavior of indigenous microorganisms in the presence of H2, which could influence the gas composition. While modeling can inform H2 dynamics, reactor-scale experiments are needed for validation. In our study, we used a high-pressure reactor to simulate injecting 2% H2 into a gas storage aquifer currently used for natural gas (CH4, 1% CO2), utilizing formation water and rock samples from the aquifer. Our research led to a kinetic model that analyzes the interactions among gas, water, rock, and microbial activities. We found that microorganisms consumed H2 and caused alkalinization, which inhibited further microbial growth and respiration. This suggests that after an initial decrease in H2 concentration, the gas storage may be stabilized in deep aquifers. Reducing CO2 levels is vital as CO2 can hinder alkalinization and enhance sulfate-reducing, methanogenic, and acetogenic activities. Notably, while H2-utilizing microorganisms were predominant, both methanogens and sulfate-reducers showed significant activity. Overall, our findings provide insights into the potential for underground H2 storage in deep aquifers, guiding future research and energy storage applications
Substrat innovant de Ni-Al2O3 comprenant une interface gradée fabriqué par SPS : application pour les modules de puissance
No full textInternational audienceTo enhance the efficiency of power modules, the development of new substrate technologies is essential. This article describes the design of a nickel-alumina substrate produced through co-sintering via spark plasma sintering (SPS), utilizing a sacrificial alumina layer approach. An Ni-Al2O3 substrate is achieved after sintering at 1150 °C under a pressure of 50 MPa. The substrate has two thick nickel metal layers, making it suitable for applications with high current densities. A well-defined interface, of thickness 30–40 μm, is formed. It consists solely of pure nickel and pure alumina with no secondary phases. The mechanism behind the formation of this interface is attributed to thermomechanical deformation during the sintering process. Mechanical tests, including shear and pull tests, demonstrate adhesion strength that meets aeronautical standards. This one-step approach, which saves both energy and time, can be applied across various fields utilizing technical ceramics
Amphiphilic Poly(β-Myrcene- co -Acrylic Acid) Copolymers Synthesized by Nitroxide-Mediated Copolymerization as Stabilizers of Terpene-Based Waterborne Latex
No full textInternational audienceTerpene-based amphiphilic copolymers have been designed as biobased stabilizers for waterborne latex synthesized by miniemulsion or emulsion polymerization of 1,3-diene terpene monomers. The pH-responsive P(AA-co-My) amphiphilic copolymers were synthesized by nitroxide-mediated radical copolymerization of β-myrcene (My) and acrylic acid (AA) with reactivity ratios of rMy = 0.24 ± 0.06 and rAA = 0.05 ± 0.10. Polymerization was controlled for My-rich monomer feed ratios (fMy,0 > 0.3). Though AA NMP exhibited reasonable control, a low fraction of My (fMy,0 ≤ 0.3) produced branched structures with higher molar masses. P(AA0.80-co-My0.20) was the most efficient copolymer to stabilize monomodal PMy latexes (Dh ∼ 150-350 nm) synthesized by miniemulsion or emulsion polymerization. P(AA-co-My) copolymers with a higher hydrophobic PMy fraction (>35 mol %) were less efficient stabilizers. The more hydrophobic β-farnesene monomer was successfully polymerized by miniemulsion polymerization, whereas emulsion polymerization failed. The biobased waterborne latexes are pH-responsive with pH-triggered flocculation at low pH
L'obligation de rembourser à un associé le solde d'un compte courant ne se transmet pas à sa filiale par l'effet d'une convention de trésorerie
No full textInternational audience(Com. 12 mars 2025, no 23-23.961, F-B, D. 2025. 490
Le remboursement du compte courant d'un associé est indépendant du rachat de ses titres sociaux
No full textInternational audience(Com. 12 févr. 2025, no 23-17.483, F-B, Rev. sociétés 2025. 336, note J.-F. Barbièri
Réforme des nullités en droit des sociétés : plus de sécurité juridique, vraiment ?
No full textInternational audience(Ord. no 2025-229 du 12 mars 2025, portant réforme du régime des nullités