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Smoothed boundary method for phase field modeling of biphasic lithiation dynamics in Li Fe PO 4 cathode
No full textInternational audienceAn appropriate description of the lithiation dynamics in biphasic primary cathode particles of Li-ion batteries requires an accurate treatment of the conditions holding at the interface between the particle and the surrounding liquid electrolyte. We propose a phase field model based on the Allen-Cahn approach within which the particle-electrolyte interface is smooth [smoothed boundary method (SBM)], to simulate arbitrarily shaped particles. Surface terms are added to the evolution equations, and SBM calculations are compared with benchmark simulations for which the boundary conditions are explicitly imposed at the borders of the calculation domain. Our findings highlight the necessity of introducing strengthening factors for the surface terms to achieve the desired conditions for the phase and elastic fields, and to enable an accurate reproduction of stress distributions within the particle. This refinement of the SBM is critical for reliable predictions of Li insertion/extraction rates and lithium diffusion behavior in the context of Li-ion batteries. We perform also a simulation under potentiostatic conditions with a full coupling of the different physical processes at play. It illustrates the applicability of our approach and demonstrates the capabilities of the SBM for a simulation of lithiation dynamics with coupled electrochemistry and mechanics
Multi-proxy documentation of past storm events in a mid-latitude coastal environment
No full textInternational audienceAs extreme events are expected to become more frequent, the combination of different environmental approaches is essential to apprehend the evolution of their occurrences. This requires a substantial time depth with a robust record of such events. This work presents a combined approach crossing historical, dendrochronological and meteorological indicators to document storm occurrences from a primary maritime pine (Pinus pinaster) tree-ring dataset extracted at Pointe d’Arcay coastal environment (western France), covering the period 1964 to 2019. From the analyses of tree-ring patterns, we identified fourteen years during which the growth of trees was strongly disturbed by significant storm winds, including those associated with Lothar and Martin (1999), Xynthia (2010), Joachim (2012), Klaus and Quinten (2009) storm systems. The analysis of wind parameters (intensity, direction, and persistence) based on ERA5 reanalysis showed a ∼85 % fit between historical archives, dendrochronology, and meteorological data. As trees were sampled through the main tilting axis, tree rings revealed the impacts of windstorms originating from only one direction. The wind intensity appears to be an important factor to produce tree-ring eccentric growth; however, it does not explain all eccentric growth cases. Thus, we analyzed wind persistence as a potential parameter influencing dendrochronological signals recorded during years without storms. We demonstrate that dendrochronology, with the support of meteorological, historical and reanalysis wind data, accurately documents storm winds in a mid-latitude coastal environment. Tree-ring archives are effective to estimate windy phases of extratropical storms and can be used to understand past storm activity with trees older than the available meteorological records
AudioGap: An AirGapped Covert Channel Exploiting the Frequency Diversity of Audio IC Electromagnetic Leakage
No full textAccepted in 49th IEEE International Conference on Computers, Software, and Applications (COMPSAC 2025)International audienceThis paper presents AudioGap, a novel Electromagnetic (EM) covert channel that exfiltrates data from airgapped systems by exploiting System Signals Auto Modulation (SSAM), a passive modulation phenomenon inherent in digital circuitry. Unlike conventional EM attacks that require fine control over hardware, AudioGap passively leverages SSAM interactions between a Local Oscillator (Lo) and nearby digital circuit to exfiltrate data. We demonstrate a covert channel based on Comb Frequency Division Multiplexing (CFDM) that achieves 2-bit-per-symbolperiod transmission, effectively doubling the throughput of traditional On-Off Keying (OOK) and Binary Amplitude Shift Keying (B-ASK). Furthermore, we develop a harmonic-based frequency detection technique that reduces the search space by a factor of 30 compared to brute-force methods, significantly improving receiver frequency search. Experimental validation using a Realtek ALC3220 audio chip and Software Defined Radio (SDR) demonstrates data transmission up to 28 cm, with up to 25.8% lower Bit Error Rate (BER) compared to state-of-the-art modulation
Discarded intravenous medication in the ICU: the GAME-OVER multicenter prospective observational study
No full textInternational audienceBackground: Medication waste is a contributor to the healthcare environmental footprint and impacts ecosystems. Data on medication waste in the intensive care unit (ICU) are scarce, and therefore are essential to develop new sustainable strategies.Methods: The GAME-OVER French multicenter prospective observational study was conducted from November 2022 to March 2023, over a 24-h period of choice, at the discretion of each participating center. Adult ICUs were enrolled in the study on a voluntary basis and hospitalized patients who did not express opposition were included in the analysis. The primary endpoint was the percentage of discarded intravenous (IV) medication in the ICU, defined as the ratio of the discarded volume to the total volume of IV medication prepared. Secondary endpoints included identifying risk factors and main reasons for medication waste and estimating its related healthcare cost.Results: Among the 81 ICUs and the 1076 enrolled patients, 408.9 L of 130 IV medications were prepared. The discarded volume was 43.8 L, resulting in a 10.7% discarded IV medication (95% Confidence Interval (CI), 9.9-11.5). Number of daily admissions/discharges in the ICU, as admission for elective surgery, Sequential Organ Failure Assessment score ≥ 7, endotracheal intubation, renal replacement therapy and body mass index were independently associated with increased discarded IV medication. Ninety percent of pharmaceutical waste was attributed to 25 key drugs, with an estimated national annual cost of 2,737,163€.Conclusions: Discarded intravenous medication in the ICU is considerable and results in significant costs for the health care system, without obvious patient-centered value. Risk factors associated with medication waste were largely nonmodifiable, emphasizing the need for sustainable practices in patient care and resource management.</b
Procédé d'obtention d'une image haute résolution d'un échantillon et dispositif d'imagerie
No full textThe invention relates to a method for obtaining a high-resolution image of a sample (2), comprising the following steps: - a) generating a sequence of successive pseudo-random illuminations, an empirical statistical property of the sequence having a predetermined value, the sequence of pseudo-random illuminations being optimized so as to increase the uniformity of the empirical statistical property; - b) exposing the sample to the sequence of pseudo-random illuminations; - c) acquiring a plurality of low-resolution images of the sample by means of an image-capturing device (40), each low-resolution image being acquired while the sample is exposed to one of the pseudo-random illuminations of the sequence; - d) calculating a measured value of an empirical statistical property of the plurality of low-resolution images, - e) determining, on the basis of the predetermined value of the empirical statistical property of the sequence of pseudo-random illuminations, a model of the empirical statistical property of the plurality of low-resolution images, - f) determining the high-resolution image by minimizing, by fitting of the model, a deviation between the model of the empirical statistical property of the plurality of low-resolution images and the measured value of the empirical statistical property of the plurality of low-resolution images.L'invention concerne un procédé d'obtention d'une image haute résolution d'un échantillon (2) comprenant les étapes suivantes : - a) génération d'une séquence d'illuminations pseudo-aléatoires successives, une propriété statistique empirique de la séquence présentant une valeur prédéterminée, ladite séquence d'illuminations pseudo-aléatoires étant optimisée de manière à augmenter l'uniformité de ladite propriété statistique empirique, - b) exposition de l'échantillon à la séquence d'illuminations pseudo-aléatoires, - c) acquisition d'une pluralité d'images basse résolution de l'échantillon par un dispositif de capture d'image (40), chaque image basse résolution étant acquise pendant que l'échantillon est exposé à l'une desdites illuminations pseudo-aléatoires de la séquence, - d) calcul d'une valeur mesurée d'une propriété statistique empirique de la pluralité d'images basse résolution, - e) détermination, sur la base de la valeur prédéterminée de la propriété statistique empirique de la séquence d'illuminations pseudo-aléatoires, d'un modèle de la propriété statistique empirique de la pluralité d'images basse résolution, - f) détermination de l'image haute résolution en minimisant, par ajustement du modèle, un écart entre le modèle de la propriété statistique empirique de la pluralité d'images basse résolution et la valeur mesurée de la propriété statistique empirique de la pluralité d'images basse résolution
The atmosphere of Titan in late northern summer from JWST and Keck observations
No full textInternational audienceSaturn's moon Titan undergoes a long annual cycle of 29.45 Earth years. Titan's northern winter and spring were investigated in detail by the Cassini-Huygens spacecraft (2004-2017), but the northern summer season remains sparsely studied. Here we present new observations from the James Webb Space Telescope (JWST) and Keck II telescope made in 2022 and 2023 during Titan's late northern summer. With JWST's Mid-Infrared Instrument we spectroscopically detected the methyl radical, the primary product of methane breakup and key to the formation of ethane and heavier molecules. With JWST's Near Infrared Spectrograph we detected several non-LTE CO and CO2 emission bands that allow measurement of these species over a wide altitude range. Lastly, with JWST's Near Infrared Camera and Keck II we imaged northern hemisphere tropospheric clouds evolving in altitude, providing new insights and constraints on seasonal convection patterns. These observations pave the way for new observations and modeling of Titan's climate and meteorology as it progresses through northern Fall equinox, when its atmosphere is expected to show dramatic seasonal changes
Control Performance Improvement of the Decoupled Exoskeleton Arm
No full textInternational audienceIn the application of the exoskeleton arm, nonlinear inertial forces impact mechanical transparency and degrade control performance. To reduce these effects, a dynamic decoupling technique is employed to linearize the dynamics of 2-DOF exoskeleton arms. Incorporating an epicyclic gear train provides a means of optimally redistributing kinetic energy, thus contributing to linearizing and decoupling the system's dynamic behavior. Furthermore, a minimum jerk trajectory is implemented for motion generation, effectively minimizing the variations in actuating forces. To ensure precise motion tracking and high energy efficiency, a linear controller with simple structure is applied. The suggested design methodology is illustrated by simulation, demonstrating its effectiveness in improving overall control performance
Femtoscopic study of the proton-proton and proton-deuteron systems in heavy-ion collisions at the LHC
No full textInternational audienceThis work reports femtoscopic correlations of pp () and pd () pairs measured in PbPb collisions at center-of-mass energy = 5.02 TeV by the ALICE Collaboration. A fit to the measured proton-proton correlation functions allows one to extract the dependence of the nucleon femtoscopic radius of the particle-emitting source on the pair transverse mass () and on the average charge particle multiplicity for three centrality intervals (010, 1030, 3050). In both cases, the expected power-law and linear scalings are observed, respectively. The measured pd correlations can be described by both two- and three-body calculations, indicating that the femtoscopy observable is not sensitive to the short-distance features of the dynamics of the p(pn) system, due to the large inter-particle distances in PbPb collisions at the LHC. Indeed, in this study, the minimum measured femtoscopic source sizes for protons and deuterons have a minimum value at and fm, respectively, for the 3050 centrality collisions. Moreover, the -scaling obtained for the pp and pd systems is compatible within 1 of the uncertainties. These findings provide new input for fundamental studies on the production of light (anti)nuclei under extreme conditions
