HAL-Ecole des Ponts ParisTech
Not a member yet
42743 research outputs found
Sort by
Analyse longitudinale (1978 - 2013) du système d'habitat français : continuité et ruptures
No full textThis thesis is based on the observation that poor housing has become a long-term problem over the last 30 years. By following an economic approach based on supply, public action has been unable to respond to successive 'crises'. An interdisciplinary overview shows that only few studies approaches housing in terms of joint dynamics of households (residential mobility) and housing (construction-destruction-rehabilitation). Drawing on the concept of the filtering process and on the vacancy chains method, this thesis proposes to address this issue by creating new concepts (social position, function and demographic profile) enabling a global and dynamic analysis of the housing system. For this purpose, we develop the Analysis of Housing Systems (ASHA) model, which simulates the impact of variations in housing supply on the system as a whole, based on household mobility (turnover rates) between housing types (vacancy chains).Adopting a retrospective, prospective and experimental approach to analysing changes in the housing system over a longitudinal period of 35 years, the ASHA model is applied to data from eight French housing surveys (INSEE, ENL, 1978 to 2013). Based on simple empirical evidence, the first analysis identifies how the current system in 2013 operates, structured into residential streams that reproduce the global society hierarchy. Simulations of successive supply-side policies extension (between 1978 and 2013) highlight that the real break in the system lies in the extension until 2013 of the 1977 reform logic, implemented during the Trente Glorieuses. Far from abandoning subsidised housing altogether, the reform instituted the creation of subsidised home ownership in favour of the upper, middle and working classes who were solvent, to the detriment of precarious, often young, households.The prospective analysis simulates the extension of the 2013 system until 2050. The results show that the system is highly unstable. On the one hand, the collapse of the private rental sector leads households to take up home ownership at an early age, leaving them vulnerable and excluded from the system. On the other hand, strong tensions in the social housing sector exist. The ASHA model also enables to conduct experimental prospective simulations of alternative housing policies such as (i) a massive construction of social housing and (ii) attempts of housing building in order to fluidify the system (adaptation to residential logics). The results do not radically alter the way the system is organised, which remains highly unequal in social terms. Consequently, due to the effects of a precarious global society, solving the problem of poor housing requires considering that a supply-side policy alone cannot respond to residential vulnerability. In this context, an overhaul of the system will probably require a reform that considers the profound transformations of both current and future social context.Cette thèse part du constat d’une pérennisation du mal-logement durant les 30 dernières années. En s’inscrivant dans une logique économique reposant sur l’offre, l’action publique se trouve dans l’incapacité à répondre aux « crises » successives. Un état des lieux interdisciplinaires montre que peu de travaux abordent la question du logement dans une dynamique conjointe des ménages (mobilité résidentielle) et des logements (construction-destruction-réhabilitation). En nous appuyant sur la notion de filtering process et la méthode des chaînes de vacances des logements (vacancy chains), notre thèse propose de dépasser ce verrou à travers la création de nouveaux concepts (position sociale, fonction et profil démographique) permettant une analyse globale et dynamique du système de l’habitat. A cette fin, nous avons développé le modèle Analyse des Systèmes d’Habitat (ASHA) qui simule l’impact des variations de l’offre de logements sur l’ensemble du système à partir des mobilités des ménages (taux de rotation) entre les types de logements (chaînes vacances).Ce modèle a été utilisé en mobilisant les données des huit Enquêtes Logement (INSEE, ENL, 1978 à 2013), pour analyser, dans une approche rétrospective, prospective et expérimentale, l’évolution du système de l’habitat dans une profondeur longitudinale de 35 ans. Par une observation empirique simple, la première analyse a permis d’identifier le fonctionnement du système actuel (2013) structuré en filières résidentielles reproduisant la hiérarchie de la société globale. Les simulations du prolongement des politiques d’offre successives (entre 1978 et 2013) ont montré que la véritable rupture du système tient au prolongement des logiques de programmation de la réforme de 1977 (promulguée dans le contexte des Trente Glorieuses) jusqu’en 2013. Loin d’abandonner totalement l’aide à la pierre, la réforme institue la création d’une accession à la propriété aidée en faveur des couches supérieures, moyennes et populaires solvables, au détriment des ménages précaires souvent jeunes. L’analyse prospective a, quant à elle, simulé le prolongement du système de 2013 jusqu’en 2050. Les résultats montrent sa forte instabilité. L’effondrement du parc locatif privé entraîne les ménages dans une accession précoce qui les fragilise et les exclue du système. D’autre part, il fait apparaître de fortes tensions dans la filière sociale. Le modèle ASHA offre également la possibilité d’effectuer des simulations prospectives expérimentales de politiques du logement alternatives : construction massive de logements sociaux et tentative de constructions de logements dans la perspective de fluidifier le système (adaptation aux logiques résidentielles). Les résultats ne modifient pas en profondeur l’organisation du système qui demeure très inégalitaire socialement. En ce sens, ils montrent que la résolution du mal-logement impose de considérer qu’une politique d’offre ne peut, à elle seule, répondre à une vulnérabilité résidentielle due aux effets d’une précarisation de la sociétale globale. Dans ce contexte, une refonte du système passe probablement par une réforme intégrant les profondes transformations du contexte social actuel et futu
Mobility dependency in peri-urban region: The case of Creil and La Roche-sur-Foron
No full textInternational audienceOver the past few decades, improvements in travel conditions have led to socio-spatial transformations, especially urban sprawl and increasing distances between housing and workplaces. These changes have favored the migration of new populations to rural and peri urban areas, including low-income households seeking affordable housing and households seeking a more natural environment. Moreover, these spatial changes have led to significant social inequalities, such as limited access to fast travel modes, which highly depends on personal characteristics (Preston, Rajé, 2007) or to residential locations with good amenities or efficient public transport services. Both of these spatial transformations of urbanized areas and the social valuing of mobility have led to the increase need to travel more frequently, sometimes further, and faster (Kaufmann, 2008). This process of “mobility dependency” results in two forms of prejudice for precarious social groups: lack of accessibility for those who do not have access to mobility, or significant financial costs, difficult and longer travelling time for mobile people but severely constrained in their movements (Fol, Gallez, 2017; Chevalier, 2020).In the face of the climate emergency and foreseeable rises in energy prices, access to local amenities and services is becoming increasingly difficult. This is especially true for less-advantaged population in rural and peri-urban areas, which are less well served by public transport and often have fewer local services and shops. Consequently, these areas, characterized by significant distances between various activities, tend to be stigmatized as fragile territories marked by unsustainable lifestyles and mobility habits predominantly reliant on cars (Fourny, Cailly, 2012). Given this scenario, reducing private car usage has become a central topic in political discourse. National and regional authorities leverage railway services as a tool for improved transportation and urban planning coordination, with the goal of reducing car dependency. Models like Transit Oriented Development are being implemented, though typically applied to densely populated urban areas.We hypothesize that in these areas characterized by diffuse urbanization, the application of urban-centric planning principles (such as densification, polarization, and massification of flows, etc.) may exacerbate mobility dependency. This is particularly true for less advantaged individuals, resulting in paradoxical effects on their access to services, amenities, and housing. In these areas, the railway service promotes the territory with good regional accessibility and sometimes a micro-local accessibility restricted to a limited perimeter around the station. However, this approach tends to overlook the daily accessibility needs of the local population, especially the less-advantaged groups, including women
Influence des propriétés radiatives des revêtements intérieurs sur le confort thermique estival des occupants.
No full textNational audienceCette étude évalue l’impact du rayonnement, tant en ondes courtes qu’en ondes longues, sur le confort thermique estival d’un logement sous un climat méditerranéen. Le solveur aux éléments finis Cast3m est couplé à une méthode de radiosité externalisée pour réaliser un calcul en régime transitoire en considérant une multitude de réflexions diffuses et spéculaires, ainsi et la transmission directe à travers les vitrages. L’influence des propriétés surfaciques intérieures sur la température physiologique équivalente (PET) est étudiée, soulignant son influence sur la distribution du rayonnement et sur le confort intérieur. Ces observations ont un intérêt dans des spécificités urbaines, comme l’absence de protections solaires et de volets sur les façades des quartiers historiques, ou le piégeage du rayonnement solaire dans les rues canyon
Analyse du comportement des tunnels, enrichie par des outils d’intelligence artificielle
No full textTunnel design relies on multiple approaches. Analytical and empirical formulations are reliable and useful for rapid estimations. Numerical modeling enables to overcome too restrictive assumptions and may be required in complex situations. However, additional efforts are needed to improve the robustness of these approaches. Especially, the time-dependent effects need to be better described to evaluate the long-term behavior of tunnels and there is a need for new constitutive models. Furthermore, to analyze the increasing amount of measurements collected during tunnelling, new techniques must be developed. Machine learning appears to be a promising field as previously unknown relationships between observations and measurements can be established. Thus, in this thesis, analytical, numerical, and data-driven approaches are emphasized to analyze the behavior of tunnels, both in the short term and in the long term. By combining these methods, a global framework for tunnel design is developed.On the one hand, an original approach is presented for the back-analysis of convergence measurements in deep tunnels to determine the constitutive parameters of the surrounding rock mass. Since time-dependent deformations can result from both the advance of the face and the delayed response of the ground, the two effects must be considered during excavations. To that end, new analytical solutions are derived by assuming an unlined circular tunnel excavated in a homogeneous isotropic ground under an initial isotropic stress field and assuming a fractional viscoelastic plastic behavior. Combining the closed-form solution that takes into account the progressive face advance and an empirical approach, convergences are back-analyzed based on a least-squares optimization method to calibrate the constitutive parameters of the ground. The presented process aims to characterize the short-term and long-term behavior of tunnels and offers the advantage of being applicable during the excavation phase as soon as convergence measurements are available. The method is illustrated by two case studies related to the Fréjus road tunnel and the Saint-Martin-la-Porte access gallery (SMP2). Additionally, the ground-lining interaction is studied through the development of an analytical solution for a lined tunnel excavated in a fractional viscoelastic ground.On the other hand, the potential use of artificial intelligence is explored. To this end, three machine learning tools are built based on synthetic data to predict both the short-term and the long-term behavior of the ground. The first model aims to assess the support pressure and the radial displacement at equilibrium in the lining and the radial displacement that occurs close to the face at the installation distance of the support. The second model computes the extrusion occurring at the core of the face considering an unlined gallery. The last model includes the time-dependent effect in the analysis to evaluate the ground-lining interaction in the long term. In particular, the bagging method is applied to neural networks to enhance generalization. Good performance is obtained using relatively scarce datasets. The modeling of the surrogate models is explained from the creation of the synthetic datasets to the evaluation of their performance and their limitations are discussed. In practice, these machine learning tools should be helpful in the field during the excavation phase.La conception des tunnels repose sur de multiples approches. Les formulations analytiques et empiriques sont fiables et utiles pour des estimations rapides. La modélisation numérique permet de surmonter les hypothèses trop restrictives et peut s'avérer nécessaire dans des situations complexes. Cependant, des efforts supplémentaires sont nécessaires pour améliorer la robustesse de ces approches. En particulier, les effets dépendant du temps doivent être mieux décrits pour évaluer le comportement à long terme des tunnels et de nouveaux modèles constitutifs sont nécessaires. De plus, de nouvelles techniques doivent être développées pour analyser la quantité croissante de mesures collectées pendant le creusement des tunnels. L'apprentissage automatique semble être un domaine prometteur car des relations jusqu'alors inconnues entre les observations et les mesures peuvent être établies. Ainsi, dans cette thèse, des approches analytiques, numériques et fondées sur les données sont étudiées pour analyser le comportement des tunnels, à la fois à court terme et à long terme. En combinant ces méthodes, un outil global est développé pour aider à la conception des tunnels. D'une part, une approche originale fondée sur une analyse inverse des mesures de convergence dans les tunnels profonds est présentée afin de déterminer les paramètres constitutifs de la roche environnante. Comme l'augmentation des déformations et des contraintes dans le temps est due à la fois à l'avancement du front de taille et à la réponse différée du terrain, ces deux effets doivent être pris en compte simultanément pendant les travaux d'excavation. À cette fin, de nouvelles solutions analytiques sont développées pour un tunnel circulaire non revêtu creusé dans un sol homogène isotrope sous un champ de contraintes initial isotrope et en supposant un comportement plastique viscoélastique fractionnaire. En combinant la solution analytique qui prend en compte l'avancement progressif du front et une approche empirique, une analyse inverse des convergences est réalisée au moyen d'une méthode d'optimisation aux moindres carrés afin de calibrer les paramètres constitutifs du terrain. Le processus présenté vise à caractériser le comportement à court et à long terme des tunnels et offre l'avantage d'être applicable pendant la phase d'excavation dès que les mesures de convergence sont disponibles. La méthode est illustrée par deux études de cas relatives au tunnel routier du Fréjus et à la galerie d'accès de Saint-Martin-la-Porte (SMP2). De plus, l'interaction entre la roche et le revêtement est étudiée à travers le développement d'une solution analytique pour un tunnel soutenu excavé dans un terrain viscoélastique fractionnaire. D'autre part, l'utilisation potentielle de l'intelligence artificielle est explorée. À cette fin, trois outils d'apprentissage automatique sont développés à partir de données synthétiques pour prédire le comportement à court et à long terme des tunnels. Le premier modèle vise à évaluer la pression et le déplacement radial à l'équilibre dans le soutènement ainsi que le déplacement radial se produisant près du front à la distance d'installation du support. Le second modèle est destiné à calculer l'extrusion se produisant au front de taille dans le cas d'une galerie non revêtue. Un dernier modèle inclut l'effet du temps dans l'analyse afin d'évaluer l'interaction entre le terrain et le revêtement à long terme. En particulier, la méthode du bagging est appliquée à un réseau de neurones pour améliorer la capacité de généralisation. Une bonne performance est obtenue en utilisant des ensembles de données relativement petits. La modélisation des modèles de substitution est expliquée depuis la création des ensembles de données synthétiques jusqu'à l'évaluation de leurs performances, et leurs limites sont discutées. En pratique, ces outils d'apprentissage automatique devraient être utiles sur le terrain pendant la phase d'excavation
CATMuS Medieval: A multilingual large-scale cross-century dataset in Latin script for handwritten text recognition and beyond
No full textBnF DataLab Projet HTRomanceInternational audienceThe surge in digitisation initiatives by Cultural Heritage institutions has facilitated online accessibility to numerous historical manuscripts. However, a substantial portion of these documents exists solely as images, lacking machine-readable text. Handwritten Text Recognition (HTR) has emerged as a crucial tool for converting these images into machine-readable formats, enabling researchers and scholars to analyse vast collections efficiently. Despite significant technological progress, establishing consistent ground truth across projects for HTR tasks, particularly for complex and heterogeneous historical sources like medieval manuscripts in Latin scripts (8th-15th century CE), remains nonetheless challenging. We introduce the Consistent Approaches to Transcribing Manuscripts (CATMuS) dataset for medieval manuscripts, which offers (1) a uniform framework for annotation practices for medieval manuscripts, a benchmarking environment (2) for evaluating automatic text recognition models across multiple dimensions thanks to rich metadata (century of production, language, genre, script, etc.), (3) for other tasks (such as script classification or dating approaches), (4) and finally for exploratory work pertaining to computer vision and digital paleography around line-based tasks, such as generative approaches.Developed through collaboration among various institutions and projects, CATMuS provides an inter-compatible dataset spanning more than 200 manuscripts and incunabula in 10 different languages, comprising over 160,000 lines of text and 5 million characters spanning from the 8th century to the 16th. The dataset's consistency in transcription approaches aims to mitigate challenges arising from the diversity in standards for medieval manuscript transcriptions, providing a comprehensive benchmark for evaluating HTR models on historical sources
Towards an advanced representation of precipitation over Morocco in a global climate model with resolution enhancement and empirical run‐time bias corrections
No full textInternational audienceMorocco, as a Mediterranean and North African country, is acknowledged as a climate change hotspot, where increased drought and related water resource shortages present a real challenge for human and natural systems. However, its geographic position and regional characteristics make the simulation of the distribution and variability of precipitation particularly challenging in the region. In this study, we propose an approach where the Laboratoire de Météorologie Dynamique Zoom (LMDZ) GCM is run with a stretched grid configuration developed with enhanced resolution (35 km) over the region, and we apply run-time bias correction to deal with the atmospheric model's systematic errors on large-scale circulation. The bias-correction terms for wind and temperature are built using the climatological mean of the adjustment terms on tendency errors in an LMDZ simulation relaxed towards ERA5 reanalyses.The free reference run with the zoomed configuration is compared to two biascorrected runs. The free run exhibits noticeable improvements in mean lowlevel circulation, high frequency variability and moisture transport and compares favourably to precipitation observations at the local scale. The mean simulated climate is substantially improved after bias correction w.r.t. to the uncorrected runs. At the regional scale, the bias-correction showed improvements in moisture transport and precipitation distribution, but no noticeable effect was observed in mean precipitation amounts, interannual variability and extreme events. To address the latter, model tuning after grid refinement and developing more "scale-aware" parameterizations are necessary. The observe
Projet COOP: Pieux énergétiques sous sollicitations combinées
No full textInternational audienceThe growing energy needs of urban areas and the environmental context are leading to the development of new geothermal technologies. In this context, energy geostructures, such as thermo-active (or energy) piles, were developed in the early 1980s and consist of heat exchanger tubes fixed to the reinforcement cages of foundation piles to extract/inject heat from/into the ground to meet the heating and cooling needs of buildings. Their specificity lies in their dual function: structural support and energy exchanger. Therefore, two aspects can be critical and should be considered in their design. The first is the nature of the cyclic thermal load acting along the energy pile, which can affect its mechanical response. Consequently, the cyclic thermal loading can cause a variation in the shear stresses at the soil-pile interface, thereby affecting the pile's load-bearing capacity. The second aspect concerns the adaptation of the design under combined lateral and axial loading, i.e. the interaction between lateral (or axial) loading and the axial (or lateral) behaviour of the energy piles, coupled with volumetric thermal loading acting on the surrounding soil and along the pile. These configurations are the most favourable for the installation of heat exchange tubes, as they mechanically require reinforcement cages along the entire lenght of the pile. The objective of the COOP project, funded by the French National Research Agency (ANR), is to improve the knowledge of the behaviour of energy piles under these complex load configurations by proposing different research topics, from real experimental case studies to physical centrifuge modelling and numerical modelling, with the final aim of providing engineers with a relevant tool for the design of energy piles under combined loading.Les besoins énergétiques croissants des zones urbaines et le contexte environnemental conduisent au développement de nouvelles technologies de géothermie. Dans ce contexte, les géostructures énergétiques, telles que les pieux thermoactifs (ou énergétiques), ont été développées au début des années 1980 et consistent en des tubes échangeurs de chaleur fixés aux cages de renforcement des pieux de fondation pour extraire/injecter de la chaleur du/dans le sol afin de répondre aux besoins de chauffage et de refroidissement des bâtiments. Leur particularité réside dans leur double fonction : rôle structural et échangeur d'énergie thermique. Par conséquent, deux aspects peuvent être critiques et doivent être pris en compte dans leur dimensionnement. Le premier est la nature de la charge thermique cyclique, qui agit sur toute la longueur du pieu et qui peut affecter sa réponse mécanique. Par conséquent, une charge thermique cyclique peut entraîner une modification des contraintes de cisaillement à l'interface sol-pieu et donc impacter la capacité portante du pieu. Le deuxième aspect concerne l’adéquation de la méthode de calcul à une charge transversale et axiale combinée, c'est-à-dire l'interaction entre la charge transversale (ou axiale) et le comportement axial (ou latéral) des pieux énergétiques, associée à une charge thermique volumétrique agissant sur le sol environnant et le long du pieu. Ces configurations sont les plus favorables à l'installation de tubes d'échange de chaleur, car elles nécessitent mécaniquement des cages de renforcement sur toute la hauteur du pieu. L'objectif du projet COOP, financé par l'Agence Nationale de la Recherche (ANR), est d'améliorer la connaissance du comportement des pieux énergétiques sous ces configurations de charge complexes en proposant différents thèmes de recherche, allant d'études de cas expérimentaux réels à la modélisation physique en centrifugeuse et à la modélisation numérique, dans le but final de fournir aux ingénieurs un outil pertinent pour le dimensionnement de pieux énergétiques sous chargements combinés
Monetizing Animal Welfare Impacts for Benefit–Cost Analysis
No full textInternational audienceAnimal welfare is often ignored in decision-making, despite widespread agreement about its importance. This is partly because of a lack of quantitative methods to assess the impacts of policies on humans and nonhumans alike on a common scale. At the same time, recent work in economics, philosophy, and animal welfare science has made progress on the fundamental theoretical challenge of estimating the well-being potential of different species on a single scale. By combining these estimates of each species’ well-being potential with assessments of how various policies impact the quality of life for these species, along with the number of animals affected, we can arrive at a framework for estimating the impact of policies on animal health and well-being. This framework allows for a quantifiable comparison between policies affecting humans and animals. For instance, it enables us to compare human QALYs to animal QALYs tailored to specific species. Hence, the intrinsic value of animal welfare impacts of policies can be monetized on the same scale as market and non-market impact for humans, facilitating benefit–cost analysis. Many challenges remain though, including issues of population ethics, political feasibility, and new complexities in addressing equity and uncertainty
Equilibrer les besoins en matériaux avec l’atténuation de l’empreinte carbone : une prospective intégrée climat-matières-économie pour la France. Support de présentation de la soutenance de thèse du jeudi 26 septembre 2024
No full textSupport de présentation de la soutenance de thèse.This document is the presentation material used during my thesis defense, titled Balancing materials needs with carbon footprint mitigation: an integrated climate-economy-materials prospective for France., defended on Thursday, September 26, 2024 at EHESS.Ce document constitue le support de présentation utilisé lors de ma soutenance de thèse, intitulée "Equilibrer les besoins matières avec l’atténuation de l’empreinte carbone : une prospective intégrée climat-matières-économie pour la France.", soutenue le jeudi 26 septembre 2024 à l'EHESS
Indo-Pacific regional extremes aggravated by changes in tropical weather patterns
No full textInternational audienceThe Pacific Walker circulation and the closely connected El Niño/Southern Oscillation influence the climate and weather of the tropical Indo-Pacific region. They specifically exert a strong control on the regional occurrence of weather extremes, such as heatwaves, heavy precipitation and prolonged dry spells, which are becoming increasingly frequent and severe. However, climate models struggle to accurately simulate large-scale circulation changes in the tropics and thus their consequences for regional weather and future climate. Here we use high-resolution ERA5 reanalysis data from 1940 to 2022 to study the occurrence trends of weather patterns in the tropical Indo-Pacific region. We find that new large-scale synoptic situations that were rarely present before the 1990s have emerged in the Indo-Pacific, while some others that were prominent have disappeared. Those new synoptic situations are associated with an unusual proportion of heatwaves and extreme precipitation in the region. These weather patterns are physically consistent with a trend towards a stronger Pacific Walker circulation, wetter and warmer conditions in Southeast Asia and drier conditions in the equatorial Pacific. These changes cannot be fully explained by El Niño/Southern Oscillation and other relevant modes of interannual variability, and other factors such as global warming, aerosol forcing, external forcing mechanisms and nonlinear mode interactions may be contributing