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Modèle de contact doigt-surface pour une interface haptique piézoélectrique
No full textInternational audienc
Modèle de contact doigt-surface pour une interface haptique piézoélectrique
No full textInternational audienc
Sécurisation de réseaux en environnement industriel : prototype de switch intelligent
No full textIndustry 4.0 is transforming industrial infrastructure by promoting an increasing convergence between Information Technology (IT) and Operational Technology (OT) systems. This interconnection improves process flexibility and efficiency but also introduces new vulnerabilities. Industrial networks are now exposed to cyber threats comparable to those found in traditional IT environments, while retaining specific constraints such as the criticality of communications, equipment heterogeneity, and protocol diversity. At the same time, recent regulations, such as the NIS2 directive and the Cyber Resilience Act, impose stricter requirements in terms of monitoring, detection, and responsiveness for connected industrial systems. In this context, this thesis proposes the development of an intelligent Ethernet switch that integrates advanced features for traffic monitoring, classification, and detection. By offloading part of the analysis directly within the communication infrastructure, this solution enables real-time identification of network flows, characterisation of network behaviours, and dynamic routing of communications according to their nature (web, email, industrial supervision, etc.) to specialised processing systems. The approach relies on passive observation, statistical modelling of exchanges, and the use of machine learning techniques. Realistic datasets, derived from mixed IT/OT environments, are used to train and evaluate the performance of the models. This architecture aims to strengthen industrial cybersecurity, reduce the load on central systems, and effectively meet emerging regulatory requirements.L’Industrie 4.0 transforme les infrastructures industrielles en favorisant une convergence croissante entre les systèmes informatiques (IT) et opérationnels (OT). Cette interconnexion améliore la flexibilité et l’efficacité des processus, mais introduit également de nouvelles vulnérabilités. Les réseaux industriels sont désormais exposés à des cybermenaces comparables à celles des environnements classiques, tout en conservant des contraintes spécifiques telles que la criticité des communications, l’hétérogénéité des équipements ou la diversité des protocoles utilisés. Parallèlement, des réglementations récentes, comme la directive NIS2 ou le Cyber Resilience Act, imposent des exigences renforcées en matière de supervision, de détection et de réactivité pour les systèmes industriels connectés. Dans ce contexte, cette thèse propose le développement d’un commutateur Ethernet intelligent intégrant des fonctions avancées de surveillance, de classification et de détection du trafic réseau. En déportant une partie de l’analyse directement au sein de l’infrastructure de communication, cette solution permet d’identifier en temps réel les flux échangés, de caractériser les comportements réseau, et d’orienter dynamiquement les communications selon leur nature (web, messagerie, supervision industrielle, etc.) vers des traitements spécialisés. L’approche repose sur l’observation passive, la modélisation statistique des échanges et l’usage de méthodes d’apprentissage automatique. Des jeux de données réalistes, issus d’environnements mixtes IT/OT, sont utilisés pour entrainer et évaluer les performances des modèles.Cette architecture vise à renforcer la cybersécurité industrielle, à soulager les systèmes centraux et à répondre efficacement aux nouvelles obligations réglementaires
Des outils de différenciation spatiale et de planification urbaine en faveur d'une gestion locale d'une ville en mutation : cas de la ville de Nabeul
No full textThis research is integrated into the field of urban planning, combining innovative tools for spatio-temporal modeling, especially in geographic information science and landscape geomediation. It focuses on the various modes and methods of spatial development that shape urban landscapes.The urban context of the city of Nabeul was selected due to the emerging spatial differentiations observed on its coastal facade (from 1975 to 2018), highlighting the dualism between urbanism and landscapequality. The adopted methodology aims to identify spatio-temporal indicators related to urbanization dynamics in a coastal context, using a cross-sectional approach based on observable, measurable, and modelable determinants. This method explores the interrelations between the structural properties of the road network, the geographical distribution of activities, and spatial representations. It introduces both quantitative and qualitative measures, such as accessibility measures and an innovative index of directional dispersion of activities that enriches the analysis model. These measures are performed using open-source tools such as QGIS, Depthmap, and R, and validated through interviews on urban preferences. The results reveal a dualism in urban development modes, notably by identifying specific configurational connections and distances in preferential behaviors, guided by local attraction factors such as the quality of coastal landscapes.Cette recherche s'intègre dans les champs de la planification urbaine, tout en associant des outils innovants de modélisation spatio-temporelle, notamment en sciences de l'information géographique et en géo médiation paysagère. L'accent est mis sur les différents modes et modalités de développement spatial qui façonnent les paysages urbains. Le cadre urbain de la ville de Nabeul a été choisi en raison des différenciations spatiales émergentes observées sur sa façade littorale (de 1975 à 2018), soulignant le dualisme entre l'urbanisme et la qualité paysagère. La méthodologie adoptée vise à identifier des indicateurs spatio-temporels relatifs aux dynamiques d'urbanisation en contexte littoral, utilisant une approche transversale qui s'appuie sur des déterminants observables, mesurables et modélisables. Cette méthode explore les interrelations entre les propriétés structurelles du réseau viaire, la distribution géographique des activités et les représentations spatiales. Elle introduit des mesures à la fois quantitatives et qualitatives, telles que des mesures d'accessibilité et un indice novateur de dispersion directionnelle des activités qui enrichit le modèle d’analyse. Ces mesures sont effectuées via des outils open source tels que QGIS, Depthmap et R, et validées par des entretiens sur les préférences urbaines. Les résultats de cette recherche révèlent un dualisme dans les modes de développement urbain, notamment par l’identification de connexions configurationnelles spécifiques et des distanciations dans les comportements préférentiels, influencées par des facteurs d'attraction locaux tels que la qualité des paysages côtiers
In situ and ex situ characterization of dislocation dynamics in photovoltaic silicon
No full textInternational audienceCrystalline silicon is the base of conventional solar cell manufacturing. Several crystallographic defects at different scales (e.g. dislocations and sub-grains) can form during the silicon material fabrication processing including: seed heating, solidification and cooling down.In our study, we investigate crystalline silicon model samples extracted from ingots fabricated with Czochralski and Cast-mono processes. These samples exhibit cellular dislocation cells. These defects may form either during or after growth, as a result of thermal and mechanical stresses. These model samples are used as seeds in our solidification experiments. Using in situ X-ray imaging during solidification (Topography and Radiography), we characterize the behavior of the dislocation cells during seed heating and the dislocation dynamics during silicon solidification. Rocking Curve Imaging analysis is also performed on bare wafers extracted from the same ingots to characterize dislocations at the scale of the ingots and to evaluate the impact of this type of dislocations among other type of defects, on the crystal distortions and formation of sub-grains.Studying this particular type of defects is crucial because they act as recombination centers for minority carriers, thus directly impacting not only the efficiency of solar cells, but also their mechanical properties, as they can serve as initiation sites for cracking. Currently, Micro-Wave phase shift (μWPS) lifetime mapping is being performed on samples from the same ingot to better understand the electrical of these defects
Adaptive resonant piezoelectric shunt using tunable inductance
No full textInternational audienceResonant piezoelectric shunts are highly effective for reducing vibrations of a structural natural mode. However, they require a fine tuning on the mechanical resonance to ensure that performances are optimal. This paper proposes a novel adaptive resonant piezoelectric shunt circuit and investigates its ability to adjust the value of the inductance. This circuit is thus used to vary the electrical frequency of the shunt and it proposes a robust strategy for vibration mitigation of a linear resonance. The principle involves incorporating a static converter controlled by a pulse-width modulation (PWM) circuit between the piezoelectric patch and the inductance. PWM is performed thanks to four-quadrant switches controlled by a duty cycle. It is demonstrated that the resonance frequency is linearly governed by the duty cycle, with a range extending from zero hertz to the resonance frequency of the initial circuit. After numerical validation of the proposed circuit, experimental validation is performed on an elastic structure where damping is optimized to reduce the amplitude of a linear resonance. In practice, a dead time is required to prevent short-circuiting the blocking capacitor, which limits the extending range to approximately 100 to 200 Hz. Additionally, variations in static gain and damping have been observed, with their causes yet to be identified
Amortissement piézoélectrique pour la réduction des vibrations d'hydrofoils sous écoulement
No full textNational audienceLes structures marines soumises à un écoulement hydrodynamique sont sujettes à des vibrations qui peuvent être causées par des lâchers tourbillonnaires dans le sillage de la structure, entraînant de la fatigue structurelle et des émissions acoustiques. Ces vibrations peuvent être réduites grâce à des shunts piézoélectriques, dont les paramètres électriques doivent être finement ajustés afin de maximiser l’amortissement du mode cible. Ce travail examine tout d’abord la capacité d’un modèle couplé fluide-structure à reproduire les vibrations induites par les vortex observées sur un hydrofoil placé dans un tunnel hydrodynamique. Le couplage d’un oscillateur structurel avec un oscillateur de van der Pol permet de reproduire la réponse en amplitude autour de la fréquence d’accrochage. Afin de construire un modèle d’ordre réduit permettant d’optimiser la stratégie de contrôle, un troisième degré de liberté correspondant au circuit électrique d’un amortisseur piézoélectrique résonant a été ajouté. Composé d’une inductance et d’une résistance connectée à un patch piézoélectrique, le circuit résonnant passif a été réglé pour minimiser l’amplitude des vibrations dans la plage de fréquence d’accrochage. Comme le shunt résonant nécessite un réglage précis sur la résonance mécanique pour garantir des performances optimales, un circuit piézoélectrique résonant ajustable est ensuite proposé en explorant la possibilité de modifier la valeur de l’inductance. Ce circuit adaptatif repose sur l’intégration d’un convertisseur statique contrôlé par un circuit de modulation de largeur d’impulsion entre le patch piézoélectrique et l’inductance. Les prédictions des différents modèles sont comparées aux résultats expérimentaux
Effect of Cheneau bracing on rib cage kinematics during breathing in adolescent idiopathic scoliosis assessed by biplanar radiography: a feasibility study
No full textInternational audienceBackground Adolescent idiopathic scoliosis (AIS) can be associated with restrictive lung disease. Brace wearing is also associated with restrictive lung disease. Due to external compression, bracing could alter the biomechanical function of the rib cage. The aim of this work was to test the feasibility of using biplanar radiography to study the impact of the brace on the rib cage kinematics during breathing. Materials and methods Twelve patients with moderate AIS, treated with Cheneau-Toulouse-Munster (CTM) brace, underwent pulmonary function test and biplanar radiography at two lung volumes: normal breathing and full inspiration with and without brace. Their spine and rib cage were reconstructed in 3D from the radiographs. Results Lung volumes were reduced after application of the brace, both by pulmonary function test and 3D reconstruction. The reduction in the rib cage volume appeared to be due to changes in rib cage width, in relation to the pressure pads. Costovertebral strategy did not seem to be modified by brace wearing. The brace tended to increase the correction of the cobb angle in maximum inspiration. Conclusions This study confirms the relevance of assessing respiratory function using biplanar radiography and 3D reconstruction. By reducing lung volumes without changing the costo-vertebral strategy, the impact of the Cheneau brace on ventilation remains to be clarified. Level of evidence III, prospective
Influence of Substrate Type Made of WC-Co on CrN/CrAlN Coatings’ Durability During Machining of Particleboard
No full textInternational audienceThis paper investigates the influence of substrate grain size on the behavior of a multilayer CrN/CrAlN coating, with the bilayer thickness varying across the cross-section in the range of 200–1000 nm. The substrate tools were made of WC-Co sintered carbide with three different grain sizes. The coatings were subjected to mechanical and tribological tests to assess their performance, including nanohardness, scratch resistance, and tribological testing. The coating’s roughness was measured using a 2D profilometer. Additionally, the chemical composition and surface morphology were analyzed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX). The durability tests were performed on an industrial CNC machine tool on the particleboard. The results revealed that tools with ultra-fine nano-grain (S) and micro-grain (T) WC-Co substrates exhibited a significant increase in tool durability by 28% and 44%, respectively. Significant differences in the microgeometry of the substrate U, especially in relation to the tool based on substrate S, explain the lack of improvement in its durability despite the use of a multilayer coating
