Portail HAL de l'Université Picardie Jules Verne
Not a member yet
32425 research outputs found
Sort by
Faut-il arrêter de croire en la culture pour la sauver ?
No full textInternational audienceLe secteur culturel se trouve aujourd’hui pris en étau. D’un côté, les attaques se multiplient : restrictions budgétaires, controverses autour d’un élitisme supposé, accusations de déconnexion ou de coût excessif. De l’autre, les acteurs du secteur, malgré leur engagement, peinent à regarder leur situation avec lucidité : une grande partie de la population demeure à distance de l’offre culturelle, tandis que beaucoup d’institutions continuent d’agir comme si leurs propositions s’adressaient « à tout le monde »
A novel Quantum Beta distributed multi-objective Particle Swarm Optimization algorithm for fake accounts detection
No full textInternational audienceDetecting fake accounts on Online Social Networks is a pressing issue due to the rise in unethical online activities. This study presents a new Quantum Beta-behaved Multi-Objective Particle Swarm Optimization Algorithm (QB-MOPSO) for machine learning-based fake account detection. QB-MOPSO aims to enhance the learning process of a random forest algorithm by simultaneously minimizing feature dimensionality and classification error rates. It proposes a novel architecture that employs two optimization profiles: one improves exploratory behavior using a quantum-behaved equation, while the other enhances exploitation through a beta function. The main contributions of this study are as follows: the design of a novel Quantum Beta Distributed Multi-Objective Particle Swarm Optimization algorithm that integrates quantum-behaved exploration and beta-distributed exploitation, the application of this algorithm to enhance artificial intelligence–based fake account detection on Twitter datasets, and a comprehensive experimental evaluation demonstrating superior accuracy, F-measure, and MCC compared to existing methods. Experimental results on two Twitter datasets with 1982 and 928 accounts respectively show QB-MOPSO's effectiveness, achieving accuracy rates of about 99.19 % and 97.52 %. Comparisons with the original architecture demonstrate QB-MOPSO's ability to enhance the performance of the random forest algorithm
Unique role of BSF glass in overcoming conventional glass-ceramic limitations in BNT for enhanced energy storage
No full textInternational audienceThis study reveals a departure from typical behavior in glass-ceramics, namely that the addition of glasses reduces dielectric polarization owing to their low dielectric character. Notably, incorporating a distinct relaxor-like class of glass (BSF) into pristine Bi0.5Na0.5TiO3 (BNT) ceramics significantly bolstered their energy storage capabilities. The latter alters the ferroelectric response, yielding slimmer P-E loops, a higher maximum polarization, and a substantially greater Wrec. Optimal compositions (2–4 wt% BSF) achieve 132.5 mJ/cm3 with 70 % peak efficiency, outperforming the 42.4 mJ/cm3 at 42 % efficiency for BNT. An interplay of elemental diffusion, interfacial polarization, and microstructural refinement promotes reversible domain switching, resulting in these enhancements. Possible field-induced polarization saturation at higher BSF contents gives rise to an exceptionally high Pmax (42.7 μC/cm2), demonstrating high polarizability levels for a glass-ceramic composite. This work highlights the unique role of the BSF glass in overcoming conventional limitations and offers a tunable route to high-efficiency, sustainable energy storage materials with potential applications in multifunctional technologies and devices
One-dimensional symmetry results for semilinear equations and inequalities on half-spaces
No full textInternational audienceWe prove new one-dimensional symmetry results for non-negative solutions, possibly unbounded, to the semilinear equation in the upper half-space . Some Liouville-type theorems are also proven in the case of differential inequalities in, even without imposing any boundary condition.Although subject to dimensional restrictions, our results apply to a broad family of functions. In particular, they apply to all non-negative that behaves at least linearly at infinity
Impact of hygro-mechanical loading on crack initiation and propagation in orthotropic media : A numerical modeling approach
No full textInternational audienceMoisture content gradients play a crucial role in the mechanics of wood, significantly affecting its properties and overall behavior. Among the adverse effects induced by moisture content variations, crack initiation and propagation remain one of the major challenges in wooden structures. This paper presents an energy-based fracture mechanics approach that relies on the computation of invariant integrals to evaluate fracture parameters in orthotropic materials subjected to moisture content gradients. A new concept of crack initiation is introduced by an algorithm based on the bisection method, which leads to automatic crack propagation under hygro-mechanical loading. The fracture criteria are derived from the energy release rate through a novel formulation of the invariant integral Ain a moisture-coupled environment. The path-independence of this newly proposed integral is verified via finite element simulations under mixed-mode loading using the Mixed-Mode Crack Growth (MMCG) specimen. Both analytical and numerical formulations account for the combined effects of mechanical and moisture-induced pressure on the crack lips. The influence of these coupled pressures on crack initiation and propagation in wood under variable moisture content conditions is introduced and discussed. For all fracture modes, the initiation and propagation criteria are obtained through a moisture-driven propagation algorithm, which triggers automatic crack growth when a critical moisture content threshold is reached. The results demonstrate that the developed analytical tool, implemented within a finite element framework provides a reliable determination of the fracture parameters of wood under moisture content variations
Assessing Mesoscale Heterogeneities in Hard Carbon Electrodes through FIB-SEM Characterization, Manufacturing and Electrochemical Modeling
No full textInternational audienceGiven the recent inclusion of sodium-ion batteries (SIBs) in the energy market, the optimization of their performance becomes a relevant research topic. At the electrode-level, the parameters selected during its manufacturing process influence its microstructure and, consequently, its electrochemical performance. Here, we address different manufacturing conditions of hard carbon (HC) negative electrodes by varying the solid content (35 wt% and 40 wt%) and the calendering degree (uncalendered and 30% calendered). The three-dimensional microstructure of each sample is acquired using focused ion beam (FIB) and scanning electron microscopy (SEM) technique, from which the real-shape of HC particles is extracted and used to generate input microstructures for a discrete element method (DEM) calendering model designed to address the mechanical electrode behavior and its effects on current collector deformation. Also, the 3D electrode microstructures are used in a finite element method (FEM) model to obtain the electrochemical performance for C-rates ranging from C/50 to C/5 and to compare these results with experimental ones. Furthermore, the DEM predictions are injected into the FEM model to validate them against the FIB-SEM reference. Overall, we study how manufacturing parameters influence the performance of HC electrodes, providing an important guideline for optimizing their production for SIBs applications. Preprint on ChemRxiv, 45 pages
Characterisation of the Novel HLA‐DRB1*13:376 Allele by Next Generation Sequencing
No full textInternational audienceABSTRACT HLA‐DRB1*13:376 differs from the HLA‐DRB1*13:86 allele by one non‐synonymous nucleotide at position 71 in exon 2
Determinants of successful completion and short-term benefits associated with temporary alcohol abstinence during Dry January in France: A prospective cohort study
No full textInternational audienceObjective: Temporary alcohol abstinence campaigns (TAAC), such as Dry January, aim to encourage behavioural change in the general population. Despite its popularity, a comprehensive evaluation of the French version has not yet been conducted. This prospective study aimed to identify characteristics associated with successful completion of the challenge (i.e., remaining alcohol-free throughout January), and to assess improvements in drinking refusal self-efficacy, sleep quality, and mental and physical health.Methods: A sample of 2123 French adults participating in Dry January 2024 completed both a baseline and a one-month follow-up questionnaire online. A broad range of variables were assessed, including demographic and contextual factors, alcohol use patterns and motives, drinking refusal self-efficacy, and health-related outcomes.Results: Key factors positively associated with successful completion included previous participation, registration, and higher baseline self-efficacy in resisting alcohol in social situations. Among registrants, greater engagement with support emails significantly increased the likelihood of abstinence. In contrast, smoking and identifying one's drinking as excessive were linked to lower odds of completion. The campaign was associated with improvements in drinking refusal self-efficacy, mental well-being, sleep quality, and physical health - particularly among participants who completed the full month without alcohol.Conclusions: This study offers the first evaluation of the French version of Dry January, highlighting the factors influencing challenge completion and short-term benefits of participation. The findings add support to the value of TAAC as scalable and impactful public health tools and underscore the importance of tailored support strategies to maximize participant success and behavioural change
Comparative effectiveness of tofacitinib versus upadacitinib for the treatment of acute severe ulcerative colitis
No full textInternational audienceBackground and aims: Tofacitinib and upadacitinib are Janus kinase (JAK) inhibitors that are increasingly used for the treatment of acute severe ulcerative colitis (ASUC). However, comparative analyses of safety and effectiveness have not been performed for their use in this setting.Methods: This multicenter, retrospective study enrolled hospitalized adult patients treated with tofacitinib or upadacitinib for ASUC between January 2019 and June 2024. The main outcomes were clinical response, clinical remission, and colectomy-free survival. Propensity-adjusted analyses using inverse probability treatment weighting (IPTW), and double robust estimations (DRE) were used to control for confounding factors.Results: In total, 111 patients (60 tofacitinib, 51 upadacitinib) were enrolled across 23 international centers. JAK inhibitors were used to induce response in 86 (77%) patients and used to maintain response after adequate intravenous steroid response in 25 (23%). The median follow up was 31 weeks (IQR 13-64). Between days 3-7 after treatment initiation, upadacitinib was associated with greater response rates 84% vs.54%,p=0.02 but response/remission were comparable at day 98 (45%/36% vs 55/48%) and day 182 (29/29% vs. 39/34%). Sub-analyses for JAK inhibitor use as salvage therapy (tofacitinib (n=35) vs. upadacitinib (n=31)) showed similar effectiveness outcomes across both groups. The probabilities of colectomy-free survival at days 98/182 for tofacitinib and upadacitinib were 79%/75% and 80%/78%, respectively, with no significant differences in the comparison of survival curves, p=0.99. Treatment failure rates (where JAK inhibitor was used to maintain remission) were similar at days 98 and 182. The frequency of adverse events was comparable.Conclusion: Tofacitinib and upadacitinib appear to have similar effectiveness and safety profiles when used for the treatment of ASUC