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Décrypter les pratiques et usages de l’eau et des produits contenant des biocides
No full textInternational audienceL’usage des substances biocides dans l’espace domestique se réalise au travers d’un ensemble de produits couramment utilisés pour l’entretien de l’espace intérieur, l’hygiène personnelle, le soin des plantes et des animaux, les travaux intérieurs. Il est intéressant de comprendre comment ses produits sont utilisés (les pratiques associées) et la perception de la toxicité/du risque que peuvent ressentir les utilisateurs. L’enquête montre dans un premier temps que le choix des produits et les façons de les utiliser sont issus de la socialisation primaire : les individus héritent de leurs parents et de leur éducation des manières de penser le propre et de l’obtenir (6,7). La socialisation secondaire qui s’effectue au travers de l’offre commerciale à laquelle les individus sont exposés, les conseils des membres de la famille ou des proches, les recommandations de médecins, les messages des médias, des réseaux sociaux ou des campagnes publiques (8) joue un rôle non négligeable, fait de compromis incessants entre les croyances propres à l’individu, ses pratiques et celles des autres. Outre ces effets de transmission à l’échelle des individus, les représentations du sale et du propre à l’échelle des sociétés (9) et sur le temps long doivent être considérées (10).L’« efficacité » est une catégorie évoquée par une majorité d’interviewés, pour rendre compte de leurs choix de produits d’entretien. Toutefois, elle n’est pas un facteur explicatif à elle seule, car elle est liée aux résultats attendus par les individus (odeur, brillance, blancheur). Les modes d’usages des produits procèdent de bricolages personnels pour entretenir leur logement et effacer toute trace de salissure ou toute contamination, dans lesquels interviennent la régularité d’utilisation, la quantité utilisée et l’effort à fournir. Les quantités sont employées en fonction des pièces de la maison, qui ne revêtent pas toutes les mêmes représentations du sale et de la salissure. Si les perceptions des risques sanitaires et environnementaux sont divergentes en fonction des personnes et des produits utilisés, elles se rattachent souvent à des expériences négatives (11) vécues avec certains produits impliquant le corps, comme des allergies, des irritations et des intoxications. Des stratégies de mise à distance de certains produits, potentiellement dangereux, au travers de l’utilisation d’outils comme un balai essoreur ou de gants, un rangement spécifique ou une utilisation parcimonieuse traduisent également une appréhension d’une certaine toxicité pour des produits bien particuliers. En revanche, le risque environnemental est lui peu présent dans les discours des individus, sauf pour ceux ayant été conscientisés à la problématique environnementale et ayant amorcé une démarche de transition vers l’usage de produits considérés comme moins nocifs
Robust optimization for geometrical design of 2D sequential interlocking assemblies
No full textInternational audienceIn the realm of sustainable construction within a circular economy, the study of demountable buildings garners significant interest. Achieving the full potential of reusing materials from disassembled structures demands innovative assembly methods surpassing conventional fasteners like nails. Although traditional joinery has addressed this challenge to some extent, it faces design limitations. Modern digital fabrication technologies, such as CNC milling and additive manufacturing, have expanded the horizons for manufacturable assemblies. This paper builds upon prior research to introduce a flexible method for crafting 2D assemblies adaptable to various geometric assumptions. It offers two contributions. Firstly, it provides a versatile numerical model for analyzing the mechanical properties of diverse designs, uncovering novel assemblies with superior mechanical performance compared to traditional configurations. Secondly, it presents an optimization approach enabling precise control over assembly and disassembly of imperfect parts by optimizing joint geometry. By integrating advanced fabrication techniques, adaptable design methods, and mechanical analysis, this research paves the way for the development of sustainable and mechanically efficient demountable buildings
On the global convergence of Wasserstein gradient flow of the Coulomb discrepancy
No full textIn this work, we study the Wasserstein gradient flow of the Riesz energy defined on the space of probability measures. The Riesz kernels define a quadratic functional on the space of measure which is not in general geodesically convex in the Wasserstein geometry, therefore one cannot conclude to global convergence of the Wasserstein gradient flow using standard arguments. Our main result is the exponential convergence of the flow to the minimizer on a closed Riemannian manifold under the condition that the logarithm of the source and target measures are Hölder continuous. To this goal, we first prove that the Polyak-Lojasiewicz inequality is satisfied for sufficiently regular solutions. The key regularity result is the global in-time existence of Hölder solutions if the initial and target data are Hölder continuous, proven either in Euclidean space or on a closed Riemannian manifold. For general measures, we prove using flow interchange techniques that there is no local minima other than the global one for the Coulomb kernel. In fact, we prove that a Lagrangian critical point of the functional for the Coulomb (or Energy distance) kernel is equal to the target everywhere except on singular sets with empty interior. In addition, singular enough measures cannot be critical points
Attributing icing precipitations trend (1951-2098) in the context of climate change in Europe
No full textInternational audienceFreezing rain and wet snow, both mentioned as “icing precipitation” in this study, are wintertime climatic events that can lead severe damages for environment and societies. At the European scale, only few studies focused on these climatic events, in comparison with North America. The objectives of this study is ( i ) to apprehend the actual and future spatio-temporal variability of the “high-impact Icing Precipitation favourable Days” (IPDs), and ( ii ) to explore the dominating climate variable controlling the IPD trends between the temperature (thermal conditions) and the precipitation (vulnerability conditions), because of the uncertainties of the future projections. Daily minimum, maximum near surface temperatures and accumulated precipitations from the E-OBS (historical period; 1951-2018) and from the Euro-Cordex initiative (future simulations; 2026-2098) are used to apprehend the IPDs. For the historical period, no clear trend emerges, either for the IPDs evolution and for the influential climate variable. For both the near- and long-term horizons, models simulate a decrease in the frequencies of IPDs that should affect almost all of Europe, except for the Scandinavia region. In addition, there would be a strong contribution of the temperature, climatic variable well simulated by regional models, as the most influential climatic conditions in the future variability of the IPDs.La pluie verglaçante et la neige collante, toutes deux mentionnées comme des « précipitations givrantes » dans cet article, sont des événements climatiques hivernaux qui peuvent entrainer de forts impacts sur les sociétés et sur l’environnement. A l’échelle européenne, peu d’études ont porté sur ces événements climatiques, en comparaison avec l’Amérique du Nord. Les objectifs de cette étude sont ( i ) d’étudier la variabilité spatio-temporelle actuelle et future des jours favorables à l’apparition d’événements de précipitations givrantes à forts impacts (« high-impact Icing Precipitation favourable Days »; IPD), et ( ii ) de cerner la variable climatique de surface qui influencerait majoritairement la variabilité des IPDs, entre la température (conditions thermiques) et les précipitations (conditions de vulnérabilité), pour évaluer la robustesse des résultats en raison des incertitudes des projections futures notamment pour les précipitations. Les températures quotidiennes minimales et maximales ainsi que les cumuls quotidiens des précipitations issues de la base de données E-OBS (période historique; 1951-2018) et de l’initiative Euro-Cordex (simulations futures; 2026-2098) sont utilisées pour étudier les IPDs. Pour la période historique, aucune tendance claire n’émerge, que ce soit pour l’évolution des IPDs ou pour la variable climatique ayant la plus forte influence. A court et long terme, les modèles simulent une diminution des fréquences d’apparition des IPDs, qui devrait toucher la quasi-totalité de l’Europe, à l’exception de la Scandinavie. De plus, il y aurait une forte contribution de la température, variable climatique bien simulée par les modèles régionaux, comme condition climatique la plus influente dans la variabilité future des IPDs
Urban Imaginaries and Landscapes Motorway: Evolution of an Infrastructure in Bordeaux, France
No full textInternational audienceMotorway infrastructure has arrived in the Bordeaux landscape in the late 1960s. It then followed and formed an imaginary and a planning thought of economic and commercial development (Harvey & Knox, 2012). The former marshes in the north of the city gradually gave way to large-scale buildings and wide carriageways - in other words, urban forms and a territory of the automobile and automobility, with the motorway as its backbone. Until the 1990s, the few morphological evolutions of the motorway were linked to public policies of commercial development and to technical engineering logics of traffic fluidity and safety (in particular, transformations and additions of interchanges as close as possible to shops).Since the 2000s, urban renewal projects have been underway in neighboring districts. The monofunctional commercial space is now inside the city and becoming the focus of new urban thinking too. The aim is to rebuild the city upon the city in line with public policies for ecological transition (planting trees, mixing uses, mobility diversification), and to create a new associated imaginary. The mutation or even disappearance of the motorway of the late 1960s becomes a subject of urban planning to create a new landscape at the entrance to the city. How do imaginaries and their translation into urban planning crystallize within a motorway morphology and modify it? We propose to study the Bordeaux case from the science and technology studies, motorway infrastructure and territory evolve as a coherent whole according to structuring orientations forged by interaction of knowledge, norms or collective imaginaries (Bulkeley et al., 2014). We propose an analysis of urban and motorway forms using graphic illustration such as aerial photography or master planning schemes to understand the material translations of planning thought (Söderström, 2000)
Éditeur de Prographes Produit-Coproduit
No full textA small application to illustrate some recent research results about Prographs and Triangulations of the sphere. With minimal interactions, the user can build rooted triangulations of the bipolar sphere. The application finely exploits the Hopf isomorphism between the triangulations of the sphere and the rectangular Young Standard tableaux with three lines. The calculations are largely carried out on the Young tableaux side.Une petite application pour illustrer quelques résultats de recherches récents sur les Prographes et Triangulations de la sphère. Avec un minimum d’interactions, l’utilisateur peut construire des triangulations enracinées de la sphère bipolaire. L'application exploite finement l'isomorphisme de Hopf entre les triangulations de la sphère et les tableaux rectangulaires de Young Standard à trois lignes. Les calculs sont en grande partie effectués du côté des tableaux de Young
Data-dependent Generalization Bounds via Variable-Size Compressibility
No full textInternational audienceIn this paper, we establish novel data-dependent upper bounds on the generalization error through the lens of a "variable-size compressibility" framework that we introduce newly here. In this framework, the generalization error of an algorithm is linked to a variable-size 'compression rate' of its input data. This is shown to yield bounds that depend on the empirical measure of the given input data at hand, rather than its unknown distribution. Our new generalization bounds that we establish are tail bounds, tail bounds on the expectation, and in-expectations bounds. Moreover, it is shown that our framework also allows to derive general bounds on any function of the input data and output hypothesis random variables. In particular, these general bounds are shown to subsume and possibly improve over several existing PAC-Bayes and data-dependent intrinsic dimension-based bounds that are recovered as special cases, thus unveiling a unifying character of our approach. For instance, a new data-dependent intrinsic dimension-based bound is established, which connects the generalization error to the optimization trajectories and reveals various interesting connections with the rate-distortion dimension of a process, the R\'enyi information dimension of a process, and the metric mean dimension
Scalable 3D Panoptic Segmentation As Superpoint Graph Clustering
No full textAccepted at 3DV 2024, Oral presentationInternational audienceWe introduce a highly efficient method for panoptic segmentation of large 3D point clouds by redefining this taskas a scalable graph clustering problem. This approach can be trained using only local auxiliary tasks, thereby eliminating the resource-intensive instance-matching step during training. Moreover, our formulation can easily be adapted to the superpoint paradigm, further increasing its efficiency. This allows our model to process scenes with millions of points and thousands of objects in a single inference. Our method, called SuperCluster, achieves a new state-of-the-art panoptic segmentation performance for two indoor scanning datasets: 50.1 PQ (+7.8) for S3DIS Area 5, and 58.7 PQ (+25.2) for ScanNetV2. We also set the first state-of-the-art for two large-scale mobile mapping benchmarks: KITTI-360 and DALES. With only 209k parameters, our model is over 30 times smaller than the best-competing method and trains up to 15 times faster. Our code and pretrained models are available at https://github.com/drprojects/superpoint_transformer
Climate policy and inequality in urban areas: Beyond incomes
No full textInternational audienceOpposition to climate policies is partly due to their impacts on inequality. But with most economic studies focused on income inequalities, the quantitative spatial effect of economic climate policy instruments is poorly understood. Here, using a model derived from the standard urban model of urban economics, we simulate a fuel tax in Cape Town, South Africa, decomposing its impacts by income class, housing type, and location, and over different timeframes, assuming that agents gradually adapt. We find that in the short term, there are both income and spatial inequalities, with low-income households or suburban dwellers more negatively impacted. These inequalities persist in the medium and long terms, as the poorest households, living in informal or subsidized housing, have few or no ways to adapt to fuel price increases by changing housing type, size or location, or transportation mode. Lowincome households living in formal housing are also impacted by the tax over the long term due to complex effects driven by competition with richer households in the housing market. Complementary policies promoting a flexible labor market, affordable public transportation, or subsidies that help lowincome households live closer to employment centers will be key to the social acceptability of climate policies
Clustering Dynamics for Improved Speed Prediction Deriving from Topographical GPS Registrations
No full textA persistent challenge in the field of Intelligent Transportation Systems is to extract accurate traffic insights from geographic regions with scarce or no data coverage. To this end, we propose solutions for speed prediction using sparse GPS data points and their associated topographical and road design features. Our goal is to investigate whether we can use similarities in the terrain and infrastructure to train a machine learning model that can predict speed in regions where we lack transportation data. For this we create a Temporally Orientated Speed Dictionary Centered on Topographically Clustered Roads, which helps us to provide speed correlations to selected feature configurations. Our results show qualitative and quantitative improvement over new and standard regression methods. The presented framework provides a fresh perspective on devising strategies for missing data traffic analysis