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Light pollution, a complex real-world problem to be tackled through an interdisciplinary approach
No full textInternational audienceThe problems of light pollution and the unprecedented issues raised by its management in the many territories currently concerned with the preservation of the nocturnal environment are complex real-world problems. This complexity and the need to grasp these issues in their entirety are now forcing researchers to go beyond traditional disciplinary approaches to truly interdisciplinary studies at the interface between the sciences of the Universe, the environmental sciences and the social sciences. In order to organize this production of interdisciplinary knowledge and encourage its transfer to territorial action, the French National Center for Scientific Research (CNRS) has created in 2021 the Nocturnal Environment Observatory (NEO — https://observatoire-environnement-nocturne.cnrs.fr/en/). Through its research programs, actions and partnerships with various territories, the Nocturnal Environment Observatory brings together a large community of scientists from different disciplines and institutions (social and natural sciences, sciences of the Universe, engineering and environmental physics), experts from different and complementary professional fields, as well as agents at the service of protected area management structures and territorial projects. Through the case study of Reunion island — a densely inhabited area under severe ecological constraints — we will present the objectives, the analytical framework, the tools and the methods of the NEO. We will show the concrete contributions to territorial action of a radically interdisciplinary research on the nocturnal environment, a socio-ecosystemic object built on the foundations of the Dark-sky movement, and therefore owes much to the work of the astronomical community since the second half of the 20th century
Ethnographie d’une foire aux dettes brésilienne
No full textInternational audienceThe paper takes as its subject a Brazilian debt fair at which debt collectors from various credit institutions and service providers (water, electricity, Internet and telephone) meet faceto-face with unpaid customers. It explores the role of events and media in the participation and expectations of debtors. The exceptional discounts, staged through reports on female debtors, shape the representations and interactions within the fair’s queues. Lastly, the paper highlights the organisers’ ability to contain debtors’ disillusionment by individualising negotiations and separating them from collective waiting areas.L’article prend pour objet une foire aux dettes brésilienne au cours de laquelle se rencontrent en face-à-face des agents de recouvrement de différents établissements de crédit, des fournisseurs de service (eau, électricité, Internet et téléphone) et des clientes en situation d’impayés. Il explore le rôle du dispositif événementiel et médiatique dans la participation et les attentes des débitrices. Les réductions exceptionnelles de montants de dettes mises en scène à travers les reportages diffusés façonnent les représentations de ces dernières et les interactions au sein des files d’attente de la foire. L’article souligne enfin la capacité des organisateurs à contenir les désillusions des débitrices à la fois en individualisant les négociations et en les cloisonnant des espaces d’attente collectifs
Machine Learning and Physics-Driven Modelling and Simulation of Multiphase Systems
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Exploiter les budgets des tâches de criticité mixte
No full textInternational audienceIn mixed-criticality systems, classical models assume an estimated execution time budget for tasks in each possible criticality, and when a job presents a budget overrun, they tend to drop the lower criticality tasks to preserve the schedulability of the higher criticality tasks. However, few studies focus on how the different execution time budgets are calculated, and it has been emphasized that tasks of lower criticality must provide a minimum service for the system to function properly. In this paper, we present a greedy heuristic for calculating the execution time budget to be allocated to real-time tasks according to their criticality and the shape of their execution time distribution. This budget is calculated with the aim of minimizing potential budget overruns. We first introduce a new statistical dispersion parameter called the maximum coefficient of variation (VWCET). This parameter describes the tendency of execution times towards the worst-case execution time and can be adjusted according to the criticality of the task. We show through experiments that the proposed heuristic reduces the probability of exceeding the time budget allocated to the task, and improves the performance of low-criticality tasks.Dans les systèmes à criticité mixte, les modèles classiques supposent un budget de temps d'exécution estimé pour les tâches de chaque criticité possible, et lorsqu'un job présente un dépassement de ce budget, ils ont tendance à rejeter les tâches à faible criticité pour préserver l'ordonnancement des tâches à criticité plus élevée. Cependant, peu d'études se concentrent sur la manière dont les différents budgets de temps d'exécution sont calculés, et il a été souligné que les tâches de faible criticité doivent fournir un service minimum pour que le système puisse fonctionner correctement. Dans cet article, nous présentons une heuristique gloutonne permettant de calculer le budget de temps d'exécution à allouer aux tâches en temps réel en fonction de leur criticité et de la forme de leur distribution de temps d'exécution. Ce budget est calculé de manière à minimiser les dépassements de budget potentiels. Nous introduisons tout d'abord un nouveau paramètre de dispersion statistique appelé coefficient de variation maximal (VWCET). Ce paramètre décrit la tendance des temps d'exécution vers le pire des cas et peut être ajusté en fonction de la criticité de la tâche. Nous montrons, par des expériences, que l'heuristique proposée réduit la probabilité de dépasser le budget temps alloué à la tâche et améliore les performances des tâches à faible criticité
Evaluation of Performance Measures for Qualifying Flood Models with Satellite Observations
No full textThis work discusses how to choose performance measures to compare numerical simulations of a flood event with one satellite image, e.g., in a model calibration or validation procedure. A series of criterion are proposed to evaluate the sensitivity of performance measures with respect to the flood extent, satellite characteristics (position, orientation), and measurements/processing errors (satellite raw values or extraction of the flood maps). Their relevance is discussed numerically in the case of one flooding event (on the Garonne River in France in February 2021), using a distribution of water depths simulated from a shallow-water model parameterized by an uncertain friction field. After identifying the performance measures respecting the most criteria, a correlation analysis is carried out to identify how various performance measures are similar. Then, a methodology is proposed to rank performance measures and select the most robust to observation errors. The methodology is shown useful at identifying four performance measures out of 28 in the study case. Note that the various top-ranked performance measures do not lead to the same calibration result as regards the friction field of the shallow-water model. The methodology can be applied to the comparison of any flood model with any flood event
Climate change impacts increase economic inequality: evidence from a systematic literature review
No full textInternational audienceAbstract While it is widely assumed that poor countries will suffer more from climate change, and that climate change will exacerbate inequalities within countries, systematic and large-scale evidence on this issue has been limited. In this systematic literature review, we examine and synthesize the evidence from the literature. Drawing from 127 individual papers, we find robust evidence that climate change impacts indeed increase economic inequality and disproportionately affect the poor, both globally and within countries on all continents. This result is valid across a wide range of physical impacts, types of economic inequality, economic sectors, and assessment methods. Furthermore, we highlight the channels through which climate change increases economic inequality. While the diversity of different approaches and metrics in the existing literature base precludes extracting a universal quantitative relation between climate change and economic inequality for use in future modelling, our systematic analysis provides an important stepping stone in that direction
Application of a new method for probabilistic fatigue analysis from strain measurements on bridges
No full textInternational audienceIncreasing loads, ageing of materials as well as environmental change make the issue of fatigue damage critical on bridges, especially in the case of old steel or iron structures. The assessment of the fatigue loads on specific elements of these assets can be carried out from on-field strain measurements with the application of classical methods involving rainflow cycle counting and the use of Palmgren-Miner's rule. However, such a fatigue assessment suffers of significant uncertainties about the real fatigue damage ratio and the consecutive residual fatigue life. A new probabilistic method for the fatigue assessment is proposed, as the result of a joint research by OSMOS Group and the Ecole des Ponts. The theoretical background of the method is described, involving a probabilistic formulation of Miner's rule and the use of a Weibull-Basquin model to describe the health of structural elements. Real field case studies are presented, on two historical iron truss road bridges in France, with a dataset of more than 18 months of continuous strain measurements used for the fitting of the probabilistic model of fatigue loads. The incidence of the quantity of data and of the number of sensors used for the analysis is discussed, along with the conclusive results concerning the probabilistic description of the residual fatigue life
Modèle 1D enrichi pour le calcul mécanique rapide : approche multiparticulaire appliquée à la fabrication additive par dépôt de cordon
No full textNational audienceUne nouvelle approche multiparticulaire (i.e., plusieurs champs de vitesse par point de matière) est présentée pour l’analyse mécanique des procédés de fabrication additive par dépôt de cordons. En effet, le modèle que nous proposons est un fil enrichi à quatre particules par point de matière permettant un maillage plus grossier dans la direction tangente du cordon, ce qui permet de réduire significativement le coût calculatoire. Le fondement théorique du modèle est rappelé brièvement et ses performances numériques (discrétisation aux éléments finis) sont comparées à un modèle 3D classique. Enfin, une étude paramétrique est proposée pour démontrer la pertinence et l’utilité de notre approche. Ce modèle mécanique rapide permet d’envisager des boucles d’optimisation sur des paramètres procédé tels que la vitesse de balayage et la puissance du laser
Deriving actionable policies from future visions: the REBALANCE project as an illustrative transition towards a sustainable mobility culture
No full textInternational audienceThe REBALANCE project focuses on the transition to a sustainable mobility culture using strategic foresight techniques such as backcasting. The project is based on the idea that the current mobility culture leads to unsustainable travel patterns. Through an open, deliberative foresight exercise, REBALANCE aims to create a new transport paradigm aligned with emerging social values, the Sustainable Development Goals (SDGs), and growing concerns about climate change.The project involved thought leaders from various fields to develop future politico-societal scenarios for mobility. A desirable scenario was validated through a European survey and targeted workshops, highlighting the values of equity and well-being. A manifesto, along with a policy roadmap and a guide to good practices, was created to encourage European decision-makers to adopt concrete measures.The roadmap proposes both short-term and long-term policies, including infrastructure development and soft policies such as information, communication, education, regulatory changes, incentives, and subsidies. Changes to cost-benefit analysis guides and impact assessment methods are also suggested.The lessons learned from the project emphasize the need to revolutionize the current mobility paradigm pragmatically, avoiding political deadlock and accusations of utopianism, while encouraging European politicians to adopt concrete measures for more sustainable mobility.Le projet REBALANCE s'intéresse à la transition vers une culture de mobilité durable en utilisant des techniques de prospective stratégique comme le backcasting. Ce projet repose sur l'idée que la culture actuelle de la mobilité conduit à des modèles de déplacement non durables. À travers un exercice délibératif et prospectif, REBALANCE vise à créer un nouveau paradigme de transport, aligné sur les valeurs sociales émergentes, les Objectifs de Développement Durable (ODD) et les préoccupations croissantes liées au changement climatique.Le projet a impliqué des experts dans divers domaines pour développer des scénarios politico-sociétaux futurs de la mobilité. Un scénario souhaitable a été validé via une enquête européenne et des ateliers ciblés. Ce scénario met en avant les valeurs d'équité et de bien-être. Un manifeste, accompagné d'une feuille de route politique et d'un guide des bonnes pratiques, a été créé pour inciter les décideurs européens à adopter des mesures concrètes.La feuille de route propose des politiques à court et long terme, incluant le développement des infrastructures et des politiques douces telles que l'information, la communication, l'éducation, des changements réglementaires, des incitations et des subventions. Les modifications des guides d'analyse coûts-avantages et des méthodes d'évaluation des impacts sont également proposées.Les leçons tirées du projet soulignent l'importance de révolutionner le paradigme actuel de la mobilité de manière pragmatique, en évitant les impasses politiques et les accusations d'utopisme, tout en stimulant les politiciens européens à adopter des mesures concrètes pour une mobilité plus durable