HAL Portal de Univ. Gustave Eiffel
Not a member yet
72847 research outputs found
Sort by
Le wargaming analytique comme méthodologie de recherche en management des systèmes d'information
No full textInternational audienceLe wargaming analytique est un dispositif de recherche permettant de répondre à des questions opérationnelles ou scientifiques. Sa renaissance actuelle, en France comme à l'international, pose la question de son déploiement de manière rigoureuse. À ce titre, notre projet propose une méthodologie qualitative de recherche-action s'appuyant sur l'enquête coopérative de Heron (1996) afin de s'extraire d'une vision positiviste et quantitativiste impossible à atteindre avec des wargames destinés à mener des réflexions très en amont de projets de systèmes d'information. Ce design de recherche sera mis en application à des fins de tests à partir de 2025 selon deux modalités : une étude de cas intégrant des questions ouvertes avec des étudiants de master et une thèse de doctorat
Rôles des administrateurs aux compétences RSE dans les comités du conseild’administration de deux banques françaises cotées : une approche par la dépendancedes ressources
No full textInternational audienceCette recherche analyse les rôles des administrateurs externes aux compétences RSE dans les différents comités du CA, qu’ils aient une fonction de surveillance (monitoring) ou de conseil (advisory), en adoptant la théorie de la dépendance des ressources. Une étude qualitative longitudinale auprès de deux banques cotées, reconnues dans le paysage bancaire français, BNP Paribas et Société Générale, est réalisée à partir de données secondaires collectées sur la période 2015 à 2023. L’utilisation de la grille des profils des administrateurs de Hillman et al (2000) appliquée aux administrateurs externes étiquetés RSE permet de mettre en évidence l’hétérogénéité et la combinaison des ressources apportées par les administrateurs dans les différents comités. Cette recherche contribue au champ de la gouvernance RSE en reliant les travaux sur le design organisationnel et la composition du CA à travers les compétences des administrateurs. Elle contribue aussi aux travaux qui mobilisent la théorie de la dépendance des ressources pour étudier la composition des comités
Longitudinal and Vertical Distribution of Tire & Road Wear Particles in an Urban Bioswale
No full textInternational audienceTire & Road Wear Particles (TRWPs) are generated by the abrasion of tire tread in contact with the road surface. These particles are a major source of microplastics in the environment and can permanently permeate ecosystems through stormwater runoff. This is concerning because TRWPs contain various chemicals and additives, which represent a proven risk for environmental compartments receiving stormwater runoff from road surfaces. Bioswales are crucial green infrastructure for managing runoff by reducing its pollutant load. The objective of the study was to quantify and characterize the longitudinal and vertical distributions of TRWPs in the soil matrix of a bioswale. The bioswale studied is the last of a series of bioswales and receives stormwater runoff from the road as well as from preceding bioswales. Soil samples were collected from the topsoil and at different core layers in the bioswale. The samples were analyzed by pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) targeting the synthetic and natural rubbers constituting the tires. The results indicate high levels of TRWP contamination for the soil near the road. A decreasing contamination profile between the inlet and outlet for the soils located in the heart of the bioswale is highlighted, which suggests a preferential zone of input and accumulation at the inlet. In the core layers, we found tire and road wear concentration decreasing with increasing soil depth. The present work aims at contributing to present literature on bioswale performance and towards informing the best management practices of such infiltration-based systems
Équité de l'accessibilité en transports collectifs dans 139 territoires : une évaluation à grande échelle
No full textThe distribution of accessibility is a key metric of transport equity. An equitable system would provide better public transport accessibility to the poorest. While several studies have evaluated accessibility distribution, spatial disturbances in the data are often overlooked, and they rely on samples with limited diversity. This has led authors to call for the use of spatial statistics and multi-city samples to enhance the literature with more precise and systematic insights.This research tests whether poorer areas benefit from better job accessibility. We develop a high-resolution accessibility index across 139 areas and analyze it using spatial econometrics models. This study is the first to assess accessibility distribution across such an exhaustive sample. Our results show that poverty zones have accessibility levels comparable to those in other areas - a pattern that falls short of equity goals. These findings call for stronger policy interventions to improve accessibility in disadvantaged neighborhoods.La distribution de l’accessibilité est une mesure clef de l’équité des transports. Un système équitable se doit de prodiguer une meilleure accessibilité par les transports collectifs aux plus défavorisés. Bien qu’un certain nombre d’études se soient déjà penchées sur cette distribution de l’accessibilité, les interférences spatiales dans les données ont souvent été sous-estimées, et les échantillons mobilisés présentent généralement une faible diversité de cas. Cela a mené des auteurs à appeler à enrichir cette littérature par le potentiel explicatif permis par les statistiques spatiales et par l’usage d’échantillons plus représentatifs.Cette recherche teste l’hypothèse d’une meilleure accessibilité dans les zones plus défavorisées. Pour ce faire, nous développons un indice d’accessibilité d’une haute résolution sur 139 territoires français, que nous analysons ensuite à l’aide de modèles d’économétrie spatiale. Cette étude est ainsi la première à évaluer la distribution de l’accessibilité sur un échantillon aussi exhaustif. Nous résultats montrent que les zones de pauvreté bénéficient de niveaux d’accessibilité globalement comparable à ceux des autres zones. Le critère d’équité évalué dans cette recherche n’est donc pas vérifié. Ces résultats plaident ainsi pour une intervention urgente des politiques publiques pour améliorer l’accessibilité dans les quartiers défavorisés
Chemisorption and physisorption of an H atom on a graphenic surface: Interaction potential and sticking probabilities
No full textInternational audienceA complete study on the sticking of a hydrogen atom on the graphene surface has been performed, including energy dissipation in the surface via phonons. The sticking probabilities of H atom in physisorption and chemisorption wells are calculated for the first time in single dynamics calculation. A mixed classical-quantum dynamics method is used. These calculations are parametrized using a Van der Waals functional to obtain potential and phonon modes. In the astrophysical context, our results show that at a grain temperature of 10 K and small initial energy of the H atom, is predominately physisorbed in the v1 vibrational state
Authentic Key Agreement Scheme for Blockchain-based Smart Grid Applications
No full textInternational audienceSmart meters have become the essential elements of smart city applications, where smart grid (SG) environments could be enabled with the real-time monitoring and collection of power usage data through trusted wireless networks. Key agreement schemes are fundamental to ensuring secure and trustworthy power usage assessment in SG systems, while also protecting data integrity and optimizing computational costs. This paper proposes an Authentic Key Agreement (AKA) scheme based on Blockchain designed to enhance the security, integrity, and efficiency of SG systems. The proposed scheme utilizes the Advanced Encryption Standard (AES) cryptographic algorithm integrated with Blockchain technology, achieving better security and computational efficiency compared to existing state-of-the-art schemes. Simulation results obtained using the NS3 simulator demonstrate a significant reduction in network delay. Specifically, when the number of nodes in a network cluster is doubled, the proposed framework achieves a 25% reduction in delay. Thus, this proposed framework offers increased efficiency, improved security, lower costs, and better transparency of power usage in SGs
Management of Gram-positive multiresistant bacteria prosthetic joint infection: a narrative review on current and innovative strategies
No full textInternational audienceBackgroundProsthetic joint infection (PJI) is a devastating complication of arthroplasty surgery, mostly caused by Gram-positive pathogens, including Staphylococcus aureus and coagulase-negative staphylococci. Multidrug resistance is of major concern in this setting: (a) it can negatively impact outcome, restricting the use of the most effective antimicrobials; (b) it may influence the choice of surgical strategies; and (c) it restrains the therapeutic options to newly labelled antimicrobials with limited experience in PJI.ObjectivesTo provide a comprehensive overview of the clinical impact of antimicrobial resistance in Gram-positive PJI and on current and innovative therapeutic strategies.SourcesThe review is based on PubMed searches for relevant topics, including multiresistant staphylococci PJI and the discussed specific therapeutic approaches. Given the very few randomized trials in this setting, discussion is mostly based on observational studies and the experience and opinion of the authors.ContentMethicillin resistance is an important concern in staphylococcal PJI, especially in coagulase-negative staphylococci. However, its impact on the outcome is controversial. Conversely, rifampicin and/or fluoroquinolone resistance are associated with worse prognosis and might be considered when defining difficult-to-treat pathogens in the PJI setting. There is very little experience with recently developed anti-Gram-positive antimicrobial in PJI, but evaluations of their antibiofilm activities are promising, and some of them might represent significant advances regarding antimicrobial tolerance (such as tedizolid) or pharmacokinetic profiles (such as dalbavancin) during long-term treatment required for PJI. Evaluation of innovative strategies in this setting is crucial, including repositioning of current surgical options using local antimicrobial delivery, pharmacokinetic monitoring and modelling to optimize antimicrobial therapy, suppressive antimicrobial treatment and/or phage-based approaches.ImplicationsPJIs caused by resistant Gram-positive bacteria—including rifampicin- and/or fluoroquinolone-resistant staphylococci—may be associated with a poorer prognosis. It is therefore essential to optimize medical and surgical management, and to find new therapeutic alternatives
Efficient and robust search of microbial genomes via phylogenetic compression
No full textInternational audienceComprehensive collections approaching millions of sequenced genomes have become central information sources in the life sciences. However, the rapid growth of these collections has made it effectively impossible to search these data using tools such as the Basic Local Alignment Search Tool (BLAST) and its successors. Here, we present a technique called phylogenetic compression, which uses evolutionary history to guide compression and efficiently search large collections of microbial genomes using existing algorithms and data structures. We show that, when applied to modern diverse collections approaching millions of genomes, lossless phylogenetic compression improves the compression ratios of assemblies, de Bruijn graphs and k-mer indexes by one to two orders of magnitude. Additionally, we develop a pipeline for a BLAST-like search over these phylogeny-compressed reference data, and demonstrate it can align genes, plasmids or entire sequencing experiments against all sequenced bacteria until 2019 on ordinary desktop computers within a few hours. Phylogenetic compression has broad applications in computational biology and may provide a fundamental design principle for future genomics infrastructure
A Voting-Based Robust Estimator Aided by INS Redundancy for Tightly Coupled GNSS/INS Integration in Urban Environment
No full textInternational audienceThe combination of Global Navigation Satellite System (GNSS) and Inertial Navigation System (INS) is widely applied for many ground transportation applications thanks to its accurate and continuous navigation service. However, with the advent of the multipath effect and non-line-of-sight (NLOS) signals caused by obstacles in urban environments, the quality of raw GNSS measurements is heavily degraded, leading to unexpected integration solutions. For this, an improved voting-based robust estimator (VBRE) algorithm assisted by the INS-derived measurement redundancy, is proposed for reasonable evaluation of satellite observation information, ensuring reliable integrated GNSS/INS solutions. The introduction of the generalized observation model allows the direct involvement of the short-term accurate INS-derived resolution in monitoring faulty GNSS measurements. Inspired by the voting theory, a residual-based collective decision framework is developed, where a group of INS-associated voters evaluates traversally each satellite observation candidate by the distance measure calculation and the agreement indicator mapping. Based on this, to determine the final GNSS measurement contribution, the detailed voter implementation is formulated with key steps including rejecting abnormal indicators, median voting, and multiple voting cycles. The above behaviors facilitate the rationality and fairness of each GNSS measurement weight allocation for integrated navigation. The proposed algorithm has been validated on two challenging open-source vehicular integration datasets in hybrid urban areas of Tokyo, Japan. The resultant 3D accuracy regarding position and velocity of Dataset I is around 60% higher than that of the Kalman filter and outperforms other existing methods. Similar performances are also achieved on more challenging Dataset II, with improvement reaching 80%.Meanwhile, this proposed algorithm presents remarkable flexibility against the various abrupt GNSS faults caused by different harsh urban areas
Hierarchy-based fuzzy segmentation and marker learning layer: theory and algorithms
No full textInternational audienceImage segmentation is inherently challenging because it is often difficult to automatically identify the object of interest in an image. To mitigate this, human-provided markers can be incorporated into the segmentation process, greatly improving accuracy. However, human interaction is an expensive resource and methods that reduce effort in interactive segmentation are of great interest. In this work, we introduce a novel marker-based segmentation layer for deep neural networks, enabling end-to-end training of a marker creation network. Our training methodology includes a loss function with two main components: (i) segmentation loss using the new differentiable segmentation layer, and (ii) a set of regularization functions that ensure the generated markers have the desired shape properties. We show that by using the proposed method, the network can automatically generate markers that achieve effective segmentation and have desirable shape characteristics. We validate our results in the training dataset and in five unseen datasets