HAL Arts et Métiers
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Etude du freinage d'un véhicule électrique en conditions réelles pour différents usagers
No full textInternational audienc
Optimisation des interactions sociales en Réalité Virtuelle (RV)
No full textHuman beings are social animals ; they develop through their interactions with others.Throughout technological advances, communication has always played an important role. Today, virtual reality promises a quality of social interaction similar to that of face-to-face interaction. This technology has the potential to do so : it allows users to engage physically and psychologically in a shared virtual environment, with each user represented by an avatar. However, at present, the perceived quality of social interaction (Koinos) mediated by virtual reality does not live up to its promises and potential. In this paper, we propose to study social interactions in VR using a transdisciplinary approach in order to understand the dynamics and elements that can influence Koinos in VR. Two experiments studied the feeling of being in the presence of others in the virtual environment (co-presence) during a collaborative task, varying the social representations and visual representations of the avatars. The analysis of these two experiments using communication models has enabled us to propose an equation for evaluating co-presence, and to propose the concept of Koinos, the Koinos model, and the Koinos method. A third experiment is presented, with the aim of studying the socially neutral representation of avatars in order to optimize Koinos.L’être humain est un animal social ; il se construit à travers ses interactions avec les autres. Au fil des évolutions technologiques, la communication a toujours eu une place importante. Aujourd’hui, la Réalité Virtuelle (RV) promet une qualité d’interactions sociales analogue à celle en face-à-face. Cette technologie en a le potentiel : elle permet d’engager physiquement et psychologiquement ses utilisateur(rice)s dans un environnement virtuel commun, chaque utilisateur(rice) représenté(e)s par un avatar. En revanche, aujourd’hui, la qualité perçue de l’interaction sociale (Koinos) médiée par la réalité virtuelle n’atteint pas ses promesses et son potentiel. Dans ce manuscrit, nous proposons d’étudier les interactions sociales en RV par une approche transdisciplinaire, afin de comprendre les dynamiques et les éléments pouvant influencer le Koinos en RV. Deux expérimentations ont étudié le sentiment d’être en présence des autres dans l’environnement virtuel (co-présence) lors d’une tâche collaborative, en variant les représentations sociales et les représentations visuelles des avatars. L’analyse de ces deux expérimentations par des modèles de communication a permis de proposer une équation évaluant la co-présence, et de proposer le concept Koinos, le modèle Koinos et la méthode Koinos. Une troisième expérimentation est présentée, dans l’objectif d’étudier la représentation socialement neutre des avatars afin d’optimiser le Koinos
How to implement an optimal user adoption and knowledge acquisition process for product lifecycle management software
No full textInternational audienceIn the scenario of digital transformation projects, user adoption remains a critical challenge, especially for complex software like product lifecycle management (PLM). Recently, digital adoption platforms (DAPs) have emerged, providing new opportunities to tackle this problem. However, many digital transformation projects still have a high failure rate due to the lack of optimal knowledge acquisition processes for users. This paper discussed the cause of this phenomenon and practiced different creative problem-solving approaches following the principle of design thinking. Accordingly, a heuristic guiding tool has been designed. This tool provides decision support for project managers in selecting the optimal digital adoption platforms according to their project context, fostering collaborations between stakeholders during the user adoption process. The proof of concept is carried out to validate the tool, using a PLM deployment project as support. The result confirms the tool's feasibility to support DAP selection in PLM deployment project
Survey and Future Trends for Cybersecurity in Maritime and Port Sectors: A Discrete Event Systems Perspective
No full textInternational audienceWith the development and widespread application of information technology, cybersecurity has become a focal point in all industry sectors. The maritime sector is no exception, with both physical and cyber threats. This survey first highlights, from a system engineering and information technology perspective, the specific architectures of on-vessel and in-port systems, as well as the communication equipment connecting them. Subsequently, cyber attacks in maritime and port domains and their potential consequences are described from various angles. Examples of real cases of cyber attacks are also reported. An overview of current key techniques used in vulnerability analysis, attack detection, and security protection is proposed before discussing cybersecurity issues in the maritime and port sectors from the particular perspective of discrete event systems. Various systems used in maritime and port domains are modeled as automata or Petri nets. Some analysis, detection, and protection approaches are then proposed to illustrate the potential of discrete event systems in this domain
Thermal ageing of flame-retardant high-density polyethylene designed for railway application
No full textInternational audienc
Estimation of interlaminar shear strength of CF / PEKK composites by full‐field data‐based numerical simulations of short beam shear tests
No full textInternational audienceA hybrid methodology is proposed to estimate the Interlaminar Shear Strength (ILSS) of Carbon Fiber and Polyetherketoneketone (CF/PEKK) composites from Short Beam Shear (SBS) tests. Digital Image Correlation (DIC) is used to capture the apparent shear behavior during loading as well as to detect the first sign of diffuse damage, characteristic of thermoplastic behavior. Simulations based on Finite Element Method (FEM) considering the orthotropic ply behavior allowed us to estimate the shear stress fields and finally, to identify the ILSS using a DIC‐based criterion. The methodology is applied to two types of manufactured laminates prepared with a non‐optimal and an optimal manufacturing cycle, to assess the impact of consolidation on macroscopic shear behavior. The estimated ILSS values (62.3 and 70.2 MPa for each manufacturing cycle, respectively) are compared with those obtained from the standard ASTM D2344 (88.1 and 95.7 MPa, respectively) whose limitations are discussed, particularly the out‐of‐plane shear behavior hypothesis. Highlights ILSS obtained via dialog between DIC full‐field data and FEM‐based simulations. Significant differences between SBS strength and ILSS for thermoplastic composites. SBS strength is not representative of ILSS for thermoplastic composites. ILSS is strongly correlated to the composite microstructure at the interply. ILSS is impacted by nonlinear shear behavior
Comparison of Different Bipolar Construct Configurations for the Correction of Adult Spine Deformity: A Finite Element Analysis
No full textInternational audiencePurposeA minimally invasive bipolar spinal fixation was recently developed to correct the deformity in pediatric neuromuscular scoliosis and has recently been adapted for adult scoliosis. Although the clinical results are promising, mechanical complications are still not negligible. In this work, alternative configurations of bipolar constructs were compared through numerical simulation, in order to evaluate stress distribution along the implant according to each configuration.MethodsThe configurations included doubling the rods, adding lumbar screws to strengthen the distal anchorage, and combining two different materials (titanium and chromium-cobalt alloy). This resulted in seven different configurations, which were implemented in a subject-specific and experimentally validated finite element model, based on the geometry of an asymptomatic subject. Von Mises stresses were compared between configurations.ResultsThe results confirm that doubling the rods reduced mid-rod stresses, as expected, but also shifted some of the load from the distal anchorage to the rods, which is a common site of implant failure. The addition of pedicle screws also reduced the stress in the distal anchorage. The configuration showing the best compromise between stress reduction and the mini-invasive character of surgery included a doubling of both rods in titanium.ConclusionsThese results should be confirmed by clinical results, but they already provide clear guidelines for the surgeon
Etude des mécanismes de dégradations des propriétés esthétiques et anticorrosion des peintures automobiles.
No full textThe durability of automotive paints is a key factor in customer satisfaction and vehicle longevity. Paint defects observed under aggressive conditions: blistering, loss of adhesion, premature corrosion, are often the result of complex phenomena combining water absorption, photochemical aging and the electrochemical behavior of treated metal substrates.This thesis, carried out in partnership between Stellantis and the PIMM laboratory, is part of an in-depth understanding of water transport in multilayer paint systems (cataphoretic paint, bases and varnishes), applied to aluminum (AA6016) or hot-dip galvanized steel (HDG) metal substrates, with zirconium-based pretreatments.The main aim of this thesis is to identify, quantify and model phenomena governing water transport in cataphoretic coating and multilayer system. To this end, a multiphysics study was carried out:Dynamic vapor sorption (DVS) was used to determine the water transport properties of the different layers and the multilayer, as a function of relative humidity and temperature.Photo-oxidative ageing, in a UV chamber (WOM and QUV), was used to assess the effect of photo-oxidation on water transport properties.Modelling tools such as the GAB equation and clustering analysis were used to interpret sorption mechanisms on a molecular scale.Comparative tests between different substrates (aluminum alloys 6016 and galvanized steel) and treatments (Suppliers A and B) enabled the morphological properties of the pre-treatment layers to be correlated with their electrochemical behavior and the overall durability of the painted system (metal and organic coating). Keywords : Paint, Multi-layer, Durability, Water transport, EIS, DVS, Galvanized steel, Aluminum alloy AA6016, Corrosion.La durabilité des peintures automobiles est un enjeu lié à la satisfaction du client et à la longévité des véhicules. Des défauts de peinture observés en clientèle, sous des conditions agressives: cloquage, perte d'adhérence, corrosion prématurée, sont souvent le résultat de phénomènes complexes combinant l'absorption d'eau, le vieillissement photochimique et le comportement électrochimique des substrats métalliques traités.Cette thèse, réalisée en partenariat entre Stellantis et le laboratoire PIMM, s'inscrit dans le cadre d'une compréhension approfondie des mécanismes de transport d'eau dans des systèmes de peinture multicouches (peinture cataphorèse, bases et vernis), appliqués sur des substrats métalliques en aluminium (AA6016) ou en acier galvanisé à chaud (HDG), avec des prétraitements à base de zirconium. Conforme à ce qu'on trouve en industrie. L'objectif principal de cette thèse est d'identifier, de quantifier et de modéliser les phénomènes régissant le transport de l'eau dans la couche cataphorèse et dans le multi-couche. Pour ce faire, une étude multiphysique est menée:La sorption de la vapeur d'eau (DVS) a été utilisée pour déterminer les propriétés transport d'eau des différentes couches et du multi-couche, en fonction de la température et l'humidité relative.Le vieillissement photo-oxydant, dans une chambre UV ( WOM et QUV), a été utilisé pour évaluer l'effet de la photo-oxydation sur les propriétés transport d'eau.Des outils de modélisation comme l'équation de GAB et l’analyse de clustering ont permis d’interpréter les mécanismes de sorption à l’échelle moléculaire.Des essais comparatifs entre différents substrats (alliages d'aluminium 6016 et acier galvanisé) et traitements (fournisseurs A et B) ont permis de corréler les propriétés morphologiques des couches du pré-traitement à leur comportement électrochimique et à la durabilité globale du système peint (métal et revêtement organique). Keywords : Peinture, Multi-couche, Durabilité, Transport d'eau, EIS, DVS, Acier galvanisé, Alliage aluminium AA6016, Corrosion
Dissimilar diffusion welding of some equiatomic FCC-structured CoCrFeNi-based binary and multi-component alloys to 316 L stainless steel.
No full textInternational audienceThis investigation was carried out to assess the joint integrity of dissimilar diffusion welding of some equiatomic binary and multi-component alloys (MCAs), viz. CoNi, CoCrNi and CoCrFeNi, to 316L stainless steel (SS316L). The microstructures and chemical composition gradients across the bond interfaces were examined by a Scanning Electron Microscope (SEM) equipped with an Energy Dispersive Spectrometer (EDS), Electron Back Scattered Diffraction (EBSD) and X-ray Diffraction (XRD) analyses, while the mechanical properties were assessed by shear tests. The binary and multi-component alloys were successfully joined to SS316L with low interfacial defects and without any compositional segregation or formation of secondary intermetallic compounds at the bond interfaces. The shear tests revealed that SS316L-CoCrNi and SS316L-CoCrFeNi joints offered good shear strength and ductility which are comparable to that of SS316L similar joints, while SS316L-CoNi joint displayed the least mechanical performances