HAL Portal UPPA (University of Pau and the Pays de l'Adour)
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Autorisation du juge des tutelles et possibilité de rechercher la nullité de l'acte passé par le tuteur d'un mineur
No full textInternational audienc
Exploring cluster formation in CO₂ + hydrocarbon mixtures: From binary to ternary systems
No full textInternational audienc
Users Pay Twice: The Hidden Energy Cost of Web Advertising
No full textInternational audienceSince the first online ad in 1994, advertising has grown into a vast ecosystem delivering billions of ads daily. Advertisements are everywhere on the Web: search engines promote results, most websites display ads, some require users to accept ads as a condition for access, video streaming services fund their infrastructure through an increasing volume of ads, and much of the gaming industry has adopted ad-based revenue models. In exchange for free access to a wide range of content, web users sacrifice their privacy and pay with personal data to enable targeted marketing, a trade-off widely studied in literature. We argue that the ad ecosystem imposes an additional, overlooked, cost on web users: energy consumption.In this paper, we present a large-scale analysis of the client-side energy consumption of ads, including their associated tracking mechanisms. We design a robust methodology aimed at realistically modeling user behavior and monitoring CPU activity. Through measurements of 724,994 website visits across diverse devices, we study the energy implications of consenting to tracking and of blocking ads through browser and network-based software. We find that consent via cookie banners increases energy consumption by a median 2.57% across all websites and devices. We also show that websites relying on real-time bidding increase median energy consumption by 33.98%. Finally, although ad-blocking solutions consume energy due to their filtering processes, we observe a median reduction of 9.62% in client-side energy consumption when using uBlock Origin.</p
La protection des animaux d’élevage dans les installations classées pour la protection de l’environnement
No full textInternational audienc
Transmission Operators Optimisation for the Iterative Solution of a Trefftz Method for Time-Harmonic Wave Propagation Problems
No full textWhen solving time-harmonic wave propagation problems in wide domains, memory considerations impose to resort to iterative solvers. Unfortunately, classic numerical methods (as Finite Element or Discontinuous Galerkin) are usually poorly adapted to these algorithms, in opposition to Trefftz methods: a natural preconditioner leads to a contracting system. Nevertheless, such an iterative convergence can be quite slow: inspired by the Domain Decomposition community, we propose to define generalised outgoing/incoming traces (on which relies an Ultra Weak Variational Formulation) by introducing transmission operators on each mesh face, intending to improve the iterative convergence. A generalised Trefftz formulation can then be obtained, and is described in a generic formalism issued from two-fields Friedrichs systems. In particular, these operators (and their matrix representation) are characterised so as to ensure the associated formulation satisfies the original weak-coercivity and contraction properties. Following DDM literature, the transmission operator is searched as an approximation of the Dirichlet-to-Neumann operator, through analytic forms and a data-driven approach, where the function linking local parameters to the operator is searched as a neural network. The iterative convergence of the associated Trefftz methods is then discussed for these choices, allowing to highlight robust gains in terms of iterations to convergence
DFT and TD‐DFT Investigation of π‐Conjugated Organic Donors for Solar Cells: Electronic, Optical, and Photovoltaic Properties
No full textInternational audienceABSTRACT This computational study investigates π‐conjugated structures based on dibenzothiophene (DBT) for high‐performance organic photovoltaics (OPVs). Leveraging experimental evidence highlighting DBTs promising optoelectronic properties, we conduct a systematic computational evaluation of modified DBT architectures. Density functional theory (DFT) calculations using Gaussian 09 were employed to optimize molecular geometries in gas and liquid phases. To identify the most accurate method for modeling electronic properties, we compare functionals (B3LYP, CAM‐B3LYP, MPW1PW91, and wB97XD) with the 6‐31G(d,p) basis set. For solid‐state simulations, CRYSTAL software with B3LYP/6‐31G(d,p) ensured consistency between isolated‐molecule and crystalline‐environment predictions. Four derivatives (M1–M4) with distinct substituted cores were analyzed via DFT/B3LYP/6‐31G(d,p). This method was used to discuss characteristics, including gap energy, frontier molecular orbitals, reactivity indices, exciton binding energy, reorganization energies, electrostatic potential, density of states, and photovoltaic parameters such as open‐circuit voltage, short‐circuit current, and fill factor with PC 61 BM as acceptor. We also obtained UV/Visible absorption wavelengths ( λ max ), excitation energies, oscillator strengths, dipole moments, and light‐harvesting efficiencies in both chloroform and gaseous phases. Every computed characteristic points to the potential of our proposed molecules for solar applications
Revealing the role of functional binder PEDOT:PSSTFSI in cathode-electrolyte interphase formation on LiFe<sub>0.4</sub>Mn<sub>0.6</sub>PO<sub>4</sub> electrodes of Li-ion battery
No full textInternational audienceThe stability of the cathode–electrolyte interphase (CEI) plays a critical role in determining the long-term performance of Li-ion batteries, particularly under high-voltage operation. This work investigates CEI formation and evolution in LiFe0.4Mn0.6PO4 (LFMP) composite positive electrodes using PEDOT:PSSTFSI, a conductive polymer that replaces both carbon black and polyvinylidene fluoride (PVDF) binder in the electrode formulation. Electrochemical tests, XRD, and XPS confirm PEDOT:PSSTFSI's electrochemical stability up to 4.5 V vs. Li+/Li and non-reactivity towards the active material. Reversible redox activity is observed in XPS, but it does not affect long-term structural or electrochemical stability. XPS analysis of C 1s, O 1s, P 2p, and F 1s spectra across different charge states reveals that PEDOT:PSSTFSI promotes a thinner, more stable CEI without altering its composition compared to carbon-containing references. This reduced interfacial degradation corresponds with improved performance at higher voltages during extended cycling. The results underscore PEDOT:PSSTFSI's promise as a multifunctional binder offering conductivity, stability, and interfacial control for advanced Li-ion positive electrodes.</p
Présentation et commentaire du film Un rêve plus long que la nuit réalisé par Niki Saint-Phalle (82 min, 1976)
No full textPrésentation et commentaire de fil
SVOCs, VOCs and microbiological contamination in sports facilities, what are people exposed to?
No full textInternational audienceThe indoor air quality of sports facilities was studied in France for different types of sports rooms (fitness, dojos,motor skills, physical activity). A total of 53 VOCs, 44 SVOCs and 7 microbiological parameters were assessed inair or settled dust. In air, levels of VOCs and SVOCs concentrations in air were like those found in schools andhomes, and SARS-CoV-2 was not identified. High concentrations of total bacteria were observed in two sportfacilities with values exceeding the indoor air guideline of European directive and the World Health Organization.In indoor dust, SVOCs ranged from <0.05 μg/g to 274 μg/g, and five SVOCs showed median concentrationshigher than in homes, daycare centers, or schools: 2-ethylhexyl diphenyl phosphate (EHDPP), triphenyl phosphate(TPP), benzophenone, 4-tert-butylphenol (4tBP), and 4-tert-octylphenol (4tOP). Considering the toxicity ofthe compounds quantified, a risk assessment seems necessary for the health of athletes and children in gyms, butexposure parameters for sports activities (dust ingestion, inhalation rates, and skin contact) are not available atthis time