HAL Portal de Univ. Gustave Eiffel
Not a member yet
72847 research outputs found
Sort by
Vallée de l’Eure : une rivière, des territoires. Projet collectif de recherche. Rapport intermédiaire 2024
No full textThe "Eure Valley: one river, many territories" program focuses on the Eure catchment area, which is a sub-basin of the Sequanian system, still relatively unexplored in terms of archaeology, geoarchaeology and history. It follows on from the major programs launched in the 1990s on the study of settlement dynamics and territories spatial organisation, which are constantly expanding to develop issues around societies transmission and change of spatial forms. As such, it merges studies into the evolution of landscape morphology and the development of cultural groups, in order to better understand the socio-environmental dynamics generated over time by the interactions between human and environment as sub-systems. The project is based on the real documentary capacities of a given corpus in terms of the evolutionary reconstitution of landscapes, both natural and man-made, and on the means to be implemented in terms of efficiency and relevance to overcome the discontinuity and fragmentation of the data, across all periods and disciplines. By deliberately placing itself in a context of scarce material documentation, the project opens the way to an exploratory and forward-looking approach, both scientifically and technologically. Beyond the insufficient corpus of archaeological deposits and sites identified in the area, it aims to reconstruct the ways in which territories and natural, cultural and social heritages were constructed over time, with an emphasis on cross-chronological dialogue and interdisciplinarity. It is also setting up an original Web-GIS platform, the aim of which is not only to centralise the collection of multidisciplinary data so that it can be cross-referenced, but also, both upstream and downstream, to assist suggestion- and decision-making in the field in terms of knowledge, conservation and a fortiori planning and risk management of our historical and natural environment.Following on from the previous surveys carried out in the middle Eure valley, the field investigations 2024 focused on a regressive analysis of the landscape, combining geomatic, archaeogeographic, geoarchaeological and geomorphological approaches.The recent opening up of IGN's high spatial and temporal resolution data (BD ORTHO® HR and IRC, BD ORTHO® Historique, RGE ALTI® 1m, LiDAR HD) has made it possible to undertake a non-invasive and systematic re-reading of the evolution of rural landscapes in the Middle Eure. The development of a methodological approach (remote sensing, photo-interpretation, geomatics) based on the cross-analysis of a wide variety of data sources has notably enabled: (1) the generation of multi-band images combining several visualization techniques (Hillshade, Local Dominance, Openness, Simple Local Relief Model, Sky-view Factor, Slope) of the digital terrain model (DTM) derived from HD LIDAR surveys and, (2) the implementation of automatic detection and vectorization protocols for micro-topographic anomalies via a deep learning approach [Part II]. More broadly, this work has led to the emergence of a range of archaeological markers in a variety of geomorphological contexts, both in open and forested environments –farms, settlements, funerary and worship sets, fortified complexes, barred spurs, land systems, roads– the sequencing of which are still uneasy to specify.In order to enrich the diachronic analysis of the spatial arrangement’s networks, it was considered essential to place all planimetric facts and archaeological markers together within the land plot documented on early 19th-century maps. The use of geohistorical data –old maps and archives– opens the way to a regressive analysis of land shapes and agricultural patterns. An initial study of the northern portion of the study area enabled us to track the evolution of landscape organisation in connection to road networks and land-use dynamics over the contemporary to modern periods [Part III].Similar work has been undertaken within the Radon watershed, combining the diachronic reconstruction of landscape organisation with a systematic study of alluvial sedimentary depositions on this specific scale. The geometry, thickness and spatial distribution of alluvial sedimentary stocks were assessed using 10 stratigraphic transects positioned across the entire sub-basin, from the elementary valleys to the main valley floor. These surveys, supplemented by 4 14C dates –32 samples were taken for radiocarbon dating and are currently being analyzed– already provide a minimum estimate of alluvial sediment volumes and specific erosion on the scale of this water supply surface (0.058 Mt/km2). They also provide a chronology of the first silty deposits within the basin, in line with the major phases of human occupation in the area (protohistoric enclosures, Roman sanctuaries, Merovingian necropolises and settlements, medieval commandry) [Part IV].All these data were ultimately shared on the PCR's Web-GIS platform, whose structure has been modified to provide greater flexibility in data input, and interpretation as well, by overcoming the generally fixed structure specific to each of the disciplinary fields involved (archaeology, history, geography, geosciences). The transdisciplinary approach has been favored to enable all participants –specialists and non-specialists alike– to easily take charge of and enrich the corpus of geo- and archaeological markers via a simplified registration form in QField [Part V].Le PCR « Vallée de l’Eure : une rivière, des territoires » s’intéresse au bassin versant de l’Eure, sous bassin du système séquanien, encore assez peu étudié sur le plan archéologique, géoarchéologique et historique. Il se place dans la continuité des grands programmes lancés à partir des années 1990 sur l’étude des dynamiques de peuplement et de l’organisation spatiale des territoires, qui ne cessent de se multiplier pour développer des problématiques autour du rôle des sociétés dans les phénomènes de transmission et de changement des formes spatiales. Il intègre à ce titre au sein de ses réflexions aussi bien des études sur l’évolution de la morphologie des paysages que sur la formation des groupes culturels, pour tenter de mieux comprendre les dynamiques socio-environnementales qu’engendrent au cours du temps les interactions entre l’homme et son milieu, entre les sous-systèmes culturel et naturel.Le projet résulte d’une réflexion sur les réelles capacités documentaires d’un corpus donné en matière de reconstitution évolutive des paysages aussi bien naturels qu’anthropiques et sur les moyens à mettre en œuvre en termes d’efficacité et de pertinence pour pallier la discontinuité et le fractionnement de la donnée, toutes périodes et disciplines confondues. En s’inscrivant volontairement dans un contexte de faible documentation matérielle, le projet ouvre sur une approche exploratoire et prospective, aussi bien sur le plan scientifique que technologique. Au-delà de l’enrichissement du corpus – somme toute maigre – de gisements archéologiques et de sites identifiés sur le secteur, il vise à restituer les modalités de la construction des territoires et des patrimoines naturels, culturels et sociaux sur le temps long, en privilégiant le dialogue transchronologique et l’interdisciplinarité. Il met également en place une plateforme Web-SIG originale, dont l’objectif est non seulement de centraliser la collecte des données pluridisciplinaires de manière à pouvoir les croiser, mais aussi, en amont comme en aval, à aider à la réflexion et à la décision sur le terrain en matière de connaissance, de conservation et a fortiori d’aménagement et de gestion des risques de notre environnement historique et naturel, passé, actuel et futur. Dans la continuité des opérations de l’année 2023 menées en vallée moyenne de l’Eure, les investigations de terrain conduites en 2024 ont privilégié une analyse paysagère et régressive, mobilisant conjointement les approches géomatique, archéogéographique, géoarchéologique et géomorphologique.L’ouverture récente des données de l’IGN à très haute résolution spatiale et temporelle (BD ORTHO® HR et IRC, BD ORTHO® Historique, RGE ALTI® 1m, LiDAR HD) a offert la possibilité d’engager une relecture non-invasive et systématique de l’évolution des paysages ruraux de l’Eure moyenne. Le déploiement d’une approche méthodologique (télédétection, photo-interprétation, géomatique) fondée sur l’analyse croisée d’une grande diversité de sources de données a notamment permis : (1) la génération d’images multi-bandes combinant plusieurs techniques de visualisation (Hillshade, Local Dominance, Openness, Simple Local Relief Model, Sky-view Factor, Slope) du modèle numérique de terrain (MNT) dérivé des levés LIDAR HD et, (2) la mise en œuvre de protocoles de détection et de vectorisation automatisés d’anomalies micro-topographiques via une approche deep learning [Partie II]. Ce travail a plus largement fait émerger un ensemble de marqueurs archéologiques dans des contextes géomorphologiques variés, en milieu ouvert comme intra-forestier – exploitations agricoles, sites d’habitat, ensembles funéraires et cultuels, noyaux fortifiés, éperons barrés, systèmes parcellaires fossiles, chemins –, mais dont l’acuité chronologique et la complexité d’emboitement scalaire restent à préciser.Afin d’enrichir l’analyse diachronique des « réseaux » d’agencement de ces territoires anciens, il est apparu indispensable de replacer l’ensemble des faits planimétriques et des marqueurs archéologiques au sein des trames parcellaires consignées sur les documents cartographiques du début du XIXe siècle. L’exploitation des données géohistoriques, et en particulier les cartes anciennes et le dépouillement d’archives, a ainsi ouvert la voie à une 1re analyse régressive des formes parcellaires et des modelés agraires. La vectorisation de ces données reportée sur la portion euroise du secteur d’étude offre à ce titre un premier cadre d’étude sur l’évolution des structures paysagères en lien avec les réseaux viaires et les dynamiques de l’occupation du sol sur les périodes contemporaines à modernes [Partie III]. Un travail similaire a été entamé au sein du bassin versant du Radon où la reconstitution diachronique des structures paysagères à travers le prisme d’une approche archéogéographique [Rapport 2023] est mise en perspective avec une étude systématique des remblaiements sédimentaires alluviaux à l’échelle du bassin versant du Radon. La géométrie, l’épaisseur et la distribution spatiale des stocks sédimentaires alluviaux ont ainsi été appréhendés à l’aide de 10 transects stratigraphiques positionnés sur l’ensemble de ce sous-bassin, des vallons élémentaires jusqu’au fond de vallée principal. Ces sondages, complétés par 4 datations 14C – 32 échantillons ont été prélevés pour des datations radiocarbones et sont en cours d’analyse –, fournissent d’ores et déjà une estimation a minima des volumes sédimentaires alluviaux et de l’érosion spécifique à l’échelle de cette surface d’alimentation en eau (0,058 Mt/km2). Ils offrent également une chronologie de la mise en place des premiers apports limoneux au sein du bassin, en accord avec les grandes phases de l’occupation humaine du secteur (enclos protohistoriques, sanctuaires d’époque romaine, nécropoles et habitats mérovingiens, commanderie médiévale) [Partie IV].L’ensemble des données obtenues ont été in fine mises en commun sur la plateforme Web-SIG du PCR, dont la structure a été modifiée afin d’offrir une plus grande souplesse dans la saisie des données et leurs interprétations en s’affranchissant d’une structuration fixiste, généralement propre à chacun des champs disciplinaires mobilisés (archéologie, histoire, géographie, géosciences). Le décloisonnement disciplinaire a été privilégié afin de permettre à l’ensemble des participants – spécialistes comme non-spécialistes – de prendre en main et d’enrichir aisément le corpus de marqueurs géo- et archéologiques via un formulaire d’enregistrement simplifié sous QField. Cette nouvelle structuration des données, questionnée et repensée afin de favoriser le dialogue interdisciplinaire et transchronologique, ouvre désormais sur de nombreuses perspectives de recherche, à l’interface entre sciences fondamentales et démarche citoyenne [Partie V]
Recyclability of vernacular adobes with high chalk content in the context of sustainable construction
No full textInternational audienceThe contemporary construction industry faces significant challenges, necessitating a response to multiple issues: reducing material resource consumption, minimizing construction waste, transitioning to carbon-neutral building methods, and fostering a circular, local, and inclusive economy. The recycling of raw earth adobes, an ancient architectural practice still employed today, appears to meet all these criteria. This study addresses the potential alterations in the physical properties of high chalk content adobes undergoing multiple cycles of reconstitution. The investigated primary adobes were collected from a recently demolished 19th century barn near Épernay, in the Champagne region located in northeastern France. During the recycling process, the bricks underwent dry crushing, wetting, mixing, molding, and drying. Careful attention was given to reproducibility through controlled water content and manual compaction techniques. Next, physical, mechanical, and thermal tests were performed. The findings indicate that the mechanical and thermal properties remain consistent over several recycling cycles. For example, mechanical tests across three recycling cycles demonstrated that the normalized peak compressive stress is barely affected. In complement, thermal conductivity and diffusivity measurements showed minimal variation across cycles, confirming that recycling did not impact these thermal parameters. The substitutability of raw earth, defined as the ability of the recycled material to reach levels of performance comparable to the original, is evidently robust. In view of these promising results, future research works should explore the possibility of combining raw earth from recycled adobes with additives such as plant-based ash, with the potential goal of improving its durability, mechanical strength, and moisture resistance
Spacers in two-stage strategy for periprosthetic infection
No full textInternational audienceIn two-stage revision of infected implants, the first stage involves removing the implant and implanting a joint spacer, and the second stage involves implanting a new prosthesis at least 6 weeks later. Spacers have two main functions: local administration of high-dose antibiotics, and preservation of the joint space by reducing soft tissue retraction and improving patient comfort until reimplantation. The present review aims to detail the necessary characteristics of antibiotics added to cement to achieve good joint diffusion, to describe the steps of two-stage revision, and to present the types of spacer available according to the joint and complications. The antibiotic used in the spacer must be heat-resistant, water-soluble and chemically stable in the cement. Gentamicin and vancomycin are generally preferred. We recommend at least 3 months’ systematic antibiotic therapy for periprosthetic joint infection. Reimplantation is performed either at 6 weeks without antibiotic washout or 3 months after 2 weeks’ washout Spacers may be static (non-articulating) or dynamic (articulating). Static spacers are mainly used in the knee or hip in cases of severe bone defect or risk of soft-tissue lesions. An articulating spacer enables some joint functions to be preserved in the knee, hip or shoulder. The most frequent complications are the dislocation of dynamic spacers and the breakage of static or dynamic spacers. To optimize efficacy and minimize complications, the biomechanical and bacteriological characteristics of spacers must be considered.Level of evidenceExpert opinion
From IoT Networks Deployment to Robust Location-based Services using the Digital Twin of a Building
No full textInternational audienceAlthough Building Information Modeling (BIM) has been around for over five decades, its integration with Big Data generated by IoT networks has raised research interest. This fusion enables the Digital Twin of a Building (DTB), a real-time virtual replica facilitating efficient location-based services, precise monitoring, and enhanced operational efficiency. Despite its alignment with the Smart City paradigm, widespread adoption is hindered by the initial investment for IoT network deployment. This article presents a comprehensive process, from optimizing IoT network deployment to implementing robust location-based services. A genetic algorithm leveraging the BIM database improves coverage by 44% compared to random deployments, while a multi-tier architecture based on deployed and roaming users’ devices extends service availability to 80% of devices without internet access, enhancing overall service quality by ∼200%. Eventually, the versatility of DTB is showcased through the use case of indoor guidance services, concluding with potential research directions using the DTB
How Has the Paris Rail Public-Transportation Network Recovered After the COVID-19 Pandemic? Applying a Mixture of Regressions Model
No full textInternational audienceThrough a combination of regulations, fear of contagion, and changes in travelers’ habits, the COVID-19 pandemic affected the mobility of public-transit ridership worldwide. To understand the longer-term effects of the pandemic on public-transit ridership, we focus on the case of Paris, France, thanks to an open 5 year record of entries into more than 500 stations. To deal with the large volume of data, we use a statistical model that performs clustering and segmentation simultaneously while incorporating many exogenous variables, such as the day of the week or lockdowns, to account for their effect on the number of entries. We carry out an in-depth analysis of the results for the segments and clusters. Examining and comparing the regression coefficients across clusters and consecutive segments allows us to draw per-cluster and per-segment conclusions. We show that the number of weekday trips decreased in most clusters and that the reduction in weekly variations is proportional to the share of weekday trips in the volume of entries before the pandemic. In addition, we characterize the changes in the weekly profile: Thursday was replaced by Tuesday as the day with the highest ridership; because of teleworking, Friday became the least crowded weekday in clusters with strong differences between weekdays and weekends, while the lowest ridership weekday remains Monday in the other clusters
Assessing Safety Risks and Vulnerabilities of Variable Speed Limits to Cyber Intrusions
No full textInternational audienceWith the rapid expansion of Intelligent Transportation Systems (ITS) for traffic management, the cyber-physical security of smart transportation infrastructures is becoming increasingly crucial. This paper investigates the impact of intentional disruptions on variable speed limit (VSL) signs within traffic networks. We present a threat model to identify vulnerabilities in the VSL communication network and potential access points for attackers. An analytical accident model was developed, and various disruption scenarios were simulated using a case study of Highway 1 in British Columbia, Canada, in SUMO (Simulation of Urban MObility) to assess the potential for crashes and safety issues resulting from VSL disruptions. Surrogate Safety Measures (SSM) were employed as key measures of safety concerns. Our findings highlight notable risks, including up to 56 additional conflicts, posed by these intentional disruptions. Various mitigation strategies are proposed to enhance traffic safety and resilience against VSL manipulation
Open-Canopy: Towards Very High Resolution Forest Monitoring
No full text22 pages, 8 figures, Submitted to NeurIPS 2024 Datasets and Benchmarks TrackInternational audienceEstimating canopy height and its changes at meter resolution from satellite imagery remains a challenging computer vision task with critical environmental applications. However, the lack of open-access datasets at this resolution hinders the reproducibility and evaluation of models. We introduce Open-Canopy, the first open-access, country-scale benchmark for very high-resolution (1.5 m) canopy height estimation, covering over 87,000 km² across France with 1.5 m panchromatic resolution satellite imagery and aerial LiDAR data. Additionally, we present Open-Canopy-, a benchmark for canopy height reduction detection between images from different years at tree level---a difficult task for current computer vision models. We evaluate state-of-the-art architectures on these benchmarks, highlighting significant challenges and opportunities for improvement. Our datasets and code are publicly available at \url{https://github.com/fajwel/Open-Canopy}
Is bicortical femoral pin insertion safe for Image-based Robotic Knee Arthroplasty Surgery ? A comparative complications analysis in 970 Consecutive Cases
No full textInternational audienceOBJECTIVES: Limited data exists on complications associated with robotic image-based system in knee arthroplasty. This study aims to document complications in robotic arm-assisted knee arthroplasties, and evaluate the system's safety by comparing two femoral pin insertion methods: bicortical diaphyseal with additional stab wounds, and unicortical metaphyseal placement through the main incision.METHODS: All patients undergoing primary knee arthroplasty with the image-based robotic system (Mako, Stryker, Mako Surgical Corp., Fort Lauderdale, FL, USA) from 1st March 2021 to 31st January 2024 with a minimum follow-up of 2 months were included. Demographics, system and non-system-related complications, as well as outcomes were recorded. Complications were categorized as either major (requiring a second surgical intervention) or minor.RESULTS: A total of 970 consecutive cases (median age 69.3 years) were analyzed. The unicortical group comprised 651 cases, while the bicortical group 319. The incidence of non-system-related complications was 2.37%, with the most common being joint stiffness (10 cases; 1.03%), followed by lateral femoral condyle fracture (4;0.41%). The overall incidence of system-specific complications was 1.03%. Pin-related femoral fractures occurred in 0.2% of cases, all postoperatively and in the unicortical group. There was no statistically significant difference between the femoral pin insertion-related complication rates among the two groups (0.3% in the unicortical, compared to 0% in the bicortical group; p-value= 0.3). Complications included tibia fracture (0.1%), delayed wound healing (0.2%), superficial wound infection (0.1%), tibia osteomyelitis (0.1%), and "exostosis" (0.2%). The major complications rate was 0.3% and minor 0.7%.CONCLUSIONS: Minimal system-specific overall complications indicate that robotic arm-assisted surgery is safe. The bicortical diaphyseal femoral pin insertion method does not increase the complication rates compared to the unicortical metaphyseal method
Osteotomies for genu varum: should we always correct at the tibia? A multicenter analysis of practices in France
No full textInternational audienc
Visibility graph and graph convolution networks-based segmentation of carbon emission in China
No full textInternational audienceCarbon emissions drive climate change. Especially with the rapid development of economy, carbon emissions are increasing in recent years, and the carbon emission data sets are more comprehensive. How to analyze the data is important. Furthermore, to find the main characteristics of carbon emission, we propose a new method of segmentation in the time series that adopts communities finding in complex network, graph convolution networks (GCN) and visibility graph (VG). Experiments on carbon emission datasets show that the detector has better detection performance than existing graph connectivity-based detectors. In addition, we find that combining the results of GCN segmentation can highlight economic geographic attributes such as resource endowment, industrial structure, and market demand in carbon emission regions, thus complementing the existing applications of complex network methods in the energy field and providing insights for decision support of carbon emissions