HAL Université de Toulouse, et Toulouse INP
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A High-Gain Reconfigurable Beam-Switched Circular Array Antenna Based on Pentagonal Radiating Elements Fed by Mutual Coupling for Sub-6 GHz Wireless Application Systems
No full textInternational audienceThis paper presents the design and development of a reconfigurable circular array antenna capable of producing ten distinct radiation beams, intended for wireless systems in the sub-6 GHz frequency band. The antenna structure is based on four pentagon-shaped radiating elements arranged symmetrically around a central circular patch, which is excited through a coaxial feed. These radiating elements are linked by four circular segments, ensuring mutual coupling for effective operation. A systematic dimensional analysis has been conducted to optimize electromagnetic performance, resulting in a compact and efficient architecture. The beam reconfiguration is achieved through the control of four PIN diodes, which allow the main radiation beam to switch among ten different orientations in the azimuth plane. Specifically, the antenna supports eight directional states, oriented at 45° intervals, and two additional bidirectional states covering opposite directions. A prototype has been fabricated and experimentally validated, confirming the steering capability of ±40° in both the XZ and YZ planes. Performance evaluation shows a maximum gain of 9.29 dBi and efficiency levels ranging from 91% to 97%. Bandwidth varies across states, with 9.72% for S1–S7, 7.45% for S2–S8, and 4.61% for S9–S10. Overall, the proposed design demonstrates optimized bandwidth, gain, efficiency, and complete azimuthal coverage
No evidence of an effect of the M184I/V on the doravirine/lamivudine/tenofovir switch efficacy in people living with HIV
No full textInternational audienceObjectives: The effect of the M184I/V mutation on the rate of virological failure (VF) in people living with HIV (PLWHIV) with plasma HIV RNA viral load (VL) <50 copies/mL switching to a triple-therapy regimen of doravirine+lamivudine+ tenofovir or abacavir has not been evaluated. Design: A retrospective national study of antiretroviral-experienced PLWHIV who were switched to a doravirine plus lamivudine and abacavir or tenofovir regimen in the context of maintenance (VL<50 copies/mL) was conducted. Virological failure (VF) was characterized by either two consecutive plasma viral loads (VL) ≥ 50 copies/mL or a single VL ≥ 200 copies/mL. Viral blip (VB) was defined as an isolated VL 50_200 copies/mL at any time up to month 6 after switching to the doravirine-containing regimen. Results: Among the 338 PLWHIV, doravirine was mainly associated with tenofovir+lamivudine (311/338, 92.0%). Of these, 45 had a M184I/V mutation before switching. VF at M6 was 14.0% and 17.8% in the absence and presence of M184I/V, respectively, with an adjusted odds ratio (aOR) of 2.409, 95%CI 0.574–10.113, p=0.21. The risk of VF at M6 was associated with the level of zenith plasma HIV VL, with an aOR of 1.646, 95% CI 1.163–2.328, p = 0.0049, per additional log 10 unit. The proportion of VB at M6 was 2.4% and 6.7% in PLWHIV in the absence and presence of M184I/V, respectively, with an aOR of 0.818, 95%CI 0.187–3.587, p = 0.7897. Conclusions: Among PLWHIV with antiretroviral experience, there was no evidence that switching to doravirine + lamivudine plus tenofovir affected short-term treatment response in individuals harboring HIV M184I/V mutations
Ageing of organic materials at the surface of Mars: A Raman study aboard Perseverance
No full textInternational audienceThe Perseverance rover is exploring Jezero crater on Mars, one of its goals being to collect samples to be returned to Earth to search for organic remains of ancient Martian life. However, the organic content of these rocks has likely suffered from the radiation environment on the surface of Mars to an extent yet to be quantified. For the first time, a 1000 sols long ageing experiment was conducted at the surface of Mars, i.e. under actual Martian conditions, relying on the 100 % organic Ertalyte target carried by Perseverance. White at landing, the Ertalyte target has turned brown with time, while its Raman signal changed, with a modification of the background (its maximum has shifted from 1500 to 2000 cm -1 ) and a reduction of the contribution of the Raman signal of Ertalyte (by a factor of 5 over the first 500 sols). Given the intrinsic resistance of the Ertalyte to UV exposure, which is not anticipated for most Martian organic materials, these results suggest that exposure at the surface of Mars will make the detection of Martian organic molecules challenging
Dossier de candidature à l'inscription sur la Liste du patrimoine mondial du pic du Midi et son observatoire.
No full textAdvection, diffusion and linear transport in a single path-sampling Monte-Carlo algorithm: Getting insensitive to geometrical refinement
No full textInternational audienceWe address the question of numerically simulating the coupling of diffusion, advection and one-speed linear transport, with a specific focus on managing geometrical complexity. We base our work on recent advances from the computer graphics community, which has developed Monte Carlo algorithms simulating linear radiation transport in physically realistic scenes, with numerical costs that remain unaffected by geometrical refinement: adding more details to the scene description does not impact the computation time. The resulting benefits in terms of engineering flexibility are already fully integrated into the cinema industry and are gradually being adopted by the video game industry. Here we demonstrate that the same insensitivity to the geometric complexity can be achieved when considering not only one-speed linear transport, but also its coupling with diffusion and advection. In this case, pure linear-transport paths are replaced with advection-diffusion/linear-transport paths, which are composed of subpaths. Each subpath represents one of the three physical phenomena, and coupling is handled by switching from one subpath (i.e. phenomenon) to another. This approach is illustrated using a porous medium involving up to 10,000 pores, with the computation time being strictly independent of the number of pores, showing its ability to facilitate engineering calculations in complex geometries
EO -Hydrolab Global river discharge estimation -expertise framework
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Insights into Oxygen Vacancy Effects on Ferroelectric Behavior of Hafnium Oxide: A Review
No full textInternational audienceFerroelectricity in hafnium oxide thin films has become a scalable and silicon‐compatible solution for nonvolatile memory and logic applications. The orthorhombic ferroelectric phase, while metastable, becomes accessible through oxygen vacancies, which play a complex role in enabling and degrading device performance. Controlled vacancy incorporation can stabilize polarization and enhance endurance, while uncontrolled migration under an electric field leads to wake‐up effects, fatigue, imprint, and leakage. This review examines how oxygen vacancies influence ferroelectric phase formation, switching behavior, and reliability in hafnium oxide systems. First‐principles simulations reveal that vacancy charge states modulate phase energetics and dipole formation. Experimental methods—including X‐ray photoelectron spectroscopy, electron paramagnetic resonance, and electron energy loss spectroscopy—offer insight into vacancy distributions at the atomic scale. Vacancy behavior is linked to remnant polarization stability and switching degradation at the device level. Process strategies such as dopant engineering, thermal annealing, and interface design are shown to be critical for vacancy control. A deeper understanding of vacancy dynamics, combined with in situ characterization and predictive modeling, is essential for advancing hafnium oxide‐based ferroelectric memories and neuromorphic architectures
Genuine multi-entropy, dihedral invariants and Lifshitz theory
No full textInternational audienceMulti-invariants are local unitary invariants of state replicas introduced as potential new probes of multipartite entanglement and correlations in quantum many-body systems. In this paper, we investigate two multi-invariants for tripartite pure states, namely multi-entropy and dihedral invariant. We compute the (genuine) multi-entropy for groundstates of Lifshitz theories, and obtain its analytical continuation to noninteger values of Rényi index. We show that the genuine multi-entropy can be expressed in terms of mutual information and logarithmic negativity. For general tripartite pure states, we demonstrate that dihedral invariants are directly related to Rényi reflected entropies. In particular, we show that the dihedral permutations of replicas are equivalent to the reflected construction, or alternatively to the realignment of density matrices
Mineralogical Changes and H2 Generation Yield During Hydrothermal Alteration of a Magnetite‐Siderite Assemblage
No full textInternational audienceTo date, the generation of natural hydrogen (H 2 ) from the alteration of Fe II ‐bearing minerals has mainly been studied through serpentinization in (ultra)mafic rocks. This study explores Banded Iron Formations (BIF), which are rich in Fe II minerals, as a potential source for H 2 . We conducted a hydrothermal experiment at 200°C with a combined magnetite‐siderite assemblage, two major components of BIF. The experiment, designed with a high water‐to‐rock ratio and a gas phase (W‐R = 300) enabled to assess mineral transformations during the alteration. Thermodynamic simulations were finally conducted, to explore H 2 ‐generating yields in more realistic geological scenarios (no gas phase, lower W‐R). Our experimental findings show that H 2 is produced through complete siderite dissolution and magnetite precipitation. Concomitantly, non‐stoichiometric primary magnetite (Fe II /Fe III < 0.5) did not enhance H 2 yield; instead, it acted as a sink for dissolved Fe 2+ , sequestrating about 10% of the iron from siderite without oxidation to recover a more ideal stoichiometry. This suggests that abundant, non‐stoichiometric magnetite in natural settings may reduce H 2 generation yields. Mass balance calculations indicate that 83% of the expected H 2 generated was unaccounted for, consistent with suspected CO 2 reduction and formation of dissolved organic compounds in the fluids. Thermodynamic simulations at varying W‐R ratios (from 300 to 1) reveal that H 2 yield ranges widely (39 mmol–73 μmol H 2 per kg of siderite), since lower W‐R prevent from siderite dissolution and enhance H 2 consumption via carbon reduction. These findings imply that low W‐R ratios in BIF ‐and other siderite‐bearing lithologies, may limit H 2 resources
Paul de Faget de Casteljau, Un pionnier de la CAGD
No full textInternational audiencewe were saddened by the loss of Paul de Faget de Casteljau, one of the most prominent founding members of the research area Computer Aided Geometric Design (CAGD) and pioneer of modern applied geometry in industry. With this special issue we take the opportunity to celebrate his contributions and to reflect on the impact of his research to the field. After a careful review process, we decided to accept 17 out of the 28 submissions, including 2 articles about Paul de Casteljau's work and life, 5 surveys summarizing the numerous research directions inspired by his ideas, and 10 research articles which showcase that these ideas are still alive and keep stimulating the CAGD community.</div