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Variabilité sous-régionale de la consommation électrique résidentielle sous scénarios de changement climatique et de climatisation en France
No full textInternational audienceThe residential sector is important for the energy transition to combat global warming. Due to the geographical variability of socio-economic factors, the highly dependent residential electricity consumption (REC) should be studied locally. This study aims to project future French REC considering climate change and air-conditioning (AC) scenarios and to quantify its spatial variability. For this purpose, a linear temperature sensitivity model fitted by annual observed electricity consumption data and historical temperature is applied at an intra-regional scale. Future temperature-sensitive REC is computed by applying the model to temperature projections under the climate change pathway RCP8.5. Three AC scenarios are considered: (1) A 100% AC rate scenario assuming that any region partially equipped with AC systems nowadays will have all its households equipped with AC, but local temperature sensitivity will no longer progress; (2) A gradual spreading scenario mimicking “do like my neighbor” behavior; (3) A combination of the two scenarios. Increasing temperatures lead to an overall REC decrease (−8 TWh by 2040 and down to −20 TWh by 2100) with significant spatial variability, which had never been quantified and mapped due to a lack of suited methodology and limited available data at the finest scale. The evolution of REC is modulated by the evolution of cooling needs and the deployment of AC systems to meet those needs. In the first 2 AC scenarios, the decrease of REC due to climate change could be totally offset in the South of France, which would then display an increase in REC. When the 2 AC scenarios are combined, an increase in REC could be seen over the whole country. The most extreme AC scenario shows a potential REC rise due to AC usage by 2% by 2040 and even 32% by 2100, which could be canceled by increasing the cooling setpoint up to 26–27 °
The Heterogeneous Impact of Market Size on Innovation: Evidence from French Firm-Level Exports
No full textInternational audienceWe analyze how demand conditions faced by a firm in its export markets affect its innovation decisions. We exploit exogenous firm-level export demand shocks and find that firms respond by patenting more; furthermore, this response is driven by the subset of initially more productive firms. The patent response arises two to five years after the shock, highlighting the time required to innovate. In contrast, the demand shock raises contemporaneous sales and employment for all firms regardless of their productivity. This skewed innovation response to common demand shocks arises naturally from a model of endogenous innovation and competition with firm heterogeneity
Hygrothermal characterization of cement mortar composites incorporating micronized miscanthus fibers
No full textInternational audienceThis work investigates both the moisture dependence of thermal properties and the hygric behavior of cement mortars incorporating different proportions of micronized miscanthus fibers up to ~7 wt%. The experimental program encompasses thermal characterization at dry (10 % RH), moderate (50 % RH), and saturated (100 % RH) states of samples, along with hygric characterization of the various mortar specimens through sorption-desorption tests, water vapor permeability assessment, Moisture Buffer value (MBV) determination, and capillary absorption tests. Thermal measurements showed a significant decrease in thermal conductivity with the addition of fibers. For a given biobased mortar composition, conductivity values were almost identical at dry/moderate RH level but exhibited an increase at saturation. This shift was attributed to the fibers' absorptive properties, which lead to a higher water content within the samples in saturated humidity environments. Collectively, the moisture sorption, moisture buffering capacities, water vapor permeability, and capillary absorption properties demonstrated consistent enhancement with rising fiber content, confirming the significant impact of plant fibers on the material's hygrothermal properties. In addition, the GAB model (Guggenheim-Andersonde Boer) was used to fit the sorption and desorption isotherms, yielding a good correspondence with experimental data. Finally, mortars with the higher fiber contents (M7.5 F and M10F with 5.70 wt% and 6.94 wt% of fibers, respectively) combined high hygroscopicity and low thermal conductivity values (even under moisture-saturated conditions), making them promising candidates for applications requiring both good hygric performance and effective insulation properties
A blueprint for a coordinated minimum effective taxation standard for ultra-high-net-worth individuals
No full textThis report presents a proposal for an internationally coordinated standard ensuring an effective taxation of ultra-high-net-worth individuals. In the baseline proposal, individuals with more than 200-100-$140 billion; (iv) this international standard would effectively address regressive features of contemporary tax systems at the top of the wealth distribution; (v) it would not substitute for, but support domestic progressive tax policies, by improving transparency about top-end wealth, reducing incentives to engage in tax avoidance, and preventing a race to the bottom; (vi) its economic impact must be assessed in light of the observed pre-tax rate of return to wealth for ultra-high-net-worth individuals which has been 7.5% on average per year (net of inflation) over the last four decades, and of the current effective tax rate of billionaires, equivalent to 0.3% of their wealth
Préface
No full textInternational audienceThis book gathers the peer-reviewed papers presented at the Second RILEM International Conference on Earthen Construction (ICEC), held in Edinburgh, United Kingdom, on July 8–10, 2024. It highlights the latest advances and innovations in the field of con earth-based building materials and construction. The conference topics encompass material characterisation and quality control, hydro-mechanical behaviour, reinforcement behaviour, seismic behaviour, in situ and field testing, additive manufacturing (3D printing), rheology, biostabilisation, molecular simulation, microstructure, durability, fire performance, hygro-thermal behaviour, life cycle analysis, climate change adaptation, economic impacts, and earthen architecture. As such, the book represents an invaluable, up-to-the-minute tool, and offers an important platform to engineers, architects, and geophysicists
Exportations agricoles, pouvoir de marché et déforestation
No full textThis paper explores how market structure shapes agricultural production and environmental outcomes, particularly deforestation. We focus on the soybean export sector in Brazil-a major driver of deforestation. We show that large exporters, operating within an oligopolistic market, exert market power by purchasing soybeans at lower prices (markdown) rather than raising prices for foreign consumers. Providing both theoretical and empirical evidence, our results suggest that this markdown behavior reduces soybean production and deforestation. Using data from 2004-2017, we find that higher market concentration, as measured by the Herfindahl-Hirschman Index (HHI), is associated with lower soybean production and deforestation. Our findings highlight the importance of trade-related supply chains in understanding deforestation dynamics.Cet article explore la manière dont la structure du marché façonne la production agricole et les résultats environnementaux, en particulier la déforestation. Nous nous concentrons sur le secteur d'exportation du soja au Brésil, un facteur majeur de déforestation. Nous montrons que les grands exportateurs, opérant au sein d’un marché oligopolistique, exercent un pouvoir de marché en achetant du soja à des prix inférieurs (markdown) plutôt qu’en augmentant les prix pour les consommateurs étrangers. En fournissant des preuves à la fois théoriques et empiriques, nos résultats suggèrent que ce comportement de démarque réduit la production de soja et la déforestation. En utilisant les données de 2004 à 2017, nous constatons qu’une concentration plus élevée du marché, telle que mesurée par l’indice Herfindahl-Hirschman (HHI), est associée à une production de soja plus faible et à la déforestation. Nos résultats soulignent l’importance des chaînes d’approvisionnement liées au commerce pour comprendre la dynamique de la déforestation
CARDS: A collection of package, revision, and miscellaneous dependency graphs
No full textCARDS (Corpus of Acyclic Repositories and Dependency Systems) is a collection of directed graphs which express dependency relations, extracted from diverse real-world sources such as package managers, version control systems, and event graphs. Each graph contains anywhere from thousands to hundreds of millions of nodes and edges, which are normalized into a simple, unified format. Both cyclic and acyclic variants are included (as some graphs, such as citation networks, are not entirely acyclic). The dataset is suitable for studying the structure of different kinds of dependencies, enabling the characterization and distinction of various dependency graph types. It has been utilized for developing and testing efficient algorithms which leverage the specificities of source version control graphs. The collection is publicly available at doi.org/10.5281/zenodo.14245890
Jet de basse couche nocturne en été dans la région parisienne : interactions avec la chaleur urbaine et les caractéristiques de surface.
No full textWith more than 50% of the global population living in cities, urban areas are critical spaces where humans directly interact with the lowest part of the atmosphere – the Atmospheric Boundary Layer (ABL). The urban surface, characterized by impervious materials and increased roughness, stores heat more effectively than vegetated areas. And also the flow is altered as urban roughness exerts substantial frictional forces on the wind thereby reducing wind speed and influencing wind direction. These effects result in a heterogeneous urban microclimate that differs significantly from rural environments. Enhanced turbulence and thermal buoyancy in cities affect the vertical structure of the ABL, leading to the formation of the Urban Boundary Layer (UBL). But also synoptic weather conditions alter dynamics in the ABL, which can impact transport processes in general and also urban-induced circulations or even near-surface micro-climates and air quality.In this study, it is examined how the regional-scale nocturnal Low-Level Jet (LLJ) interacts with the urban atmosphere and surface characteristics of Paris, France, the second-largest metropolis in Europe with about 12 million inhabitants. The wind field and turbulence profiles were monitored using Doppler Wind Lidars (DWL). Wind profile observations were recorded simultaneously at two locations: an urban site in central Paris and a suburban site approximately 25 km southwest of the city center. These observations were used to detect the nocturnal LLJ using an automatic algorithm, allowing for a detailed investigation of LLJ characteristics in the region during the summer periods of 2022 and 2023. Jets were detected on 50-70% of the examined nights, often simultaneously at both urban and suburban sites, highlighting the regional spatial extent of the LLJ. The jets typically emerged around sunset, with a mean duration of approximately 10 hours. Many jets showed temporal evolution signatures indicating that the inertial oscillation mechanism plays a role in jet development, characterized by clockwise veering of the wind direction, rapid acceleration, and slower deceleration. Additionally, depending on the core height and wind speed, the LLJ induces mechanical turbulence down to the urban canopy layer and modulates the intensity of the Urban Heat Island (UHI), i.e. the spatial temperature difference between the city and the rural surroundings. This study demonstrates how DWL observations in cities provide valuable insights into near-surface processes relevant to human and environmental health.Avec plus de 50 % de la population mondiale vivant en ville, les zones urbaines sont des zones critiques où les humains interagissent directement avec la partie la plus basse de l'atmosphère – la Couche Limite Atmosphérique (CLA). La surface urbaine, caractérisée par des matériaux imperméables et une rugosité accrue, stocke la chaleur plus efficacement que les zones végétalisées. De plus, l'écoulement est modifié car la rugosité urbaine exerce des forces de friction substantielles sur le vent, réduisant ainsi la vitesse du vent et influençant sa direction. Ces effets entraînent un microclimat urbain hétérogène qui diffère considérablement des environnements ruraux. La turbulence accrue et la flottabilité thermique dans les villes affectent la structure verticale de la CLA, conduisant à la formation de la Couche Limite Urbaine (CLU). En outre, les conditions météorologiques synoptiques modifient les dynamiques dans la CLA, ce qui peut impacter les processus de transport en général, ainsi que les circulations induites par l’environnement urbain ou encore les microclimats de surface et la qualité de l'air.Dans cette étude, nous examinons comment le Jet de Basse Couche (Low-Level Jet en anglais, LLJ) nocturne à l'échelle régionale interagit avec l'atmosphère urbaine et les caractéristiques de surface de Paris, France, la deuxième plus grande métropole d'Europe avec environ 12 millions d'habitants. Le champ de vent et les profils de turbulence ont été surveillés à l'aide de Lidars Doppler (LD). Les observations des profils de vent ont été enregistrées simultanément à deux endroits : un site urbain dans le centre de Paris et un site suburbain à environ 25 km au sud-ouest du centre-ville. Ces observations ont été utilisées pour détecter le LLJ nocturne à l'aide d'un algorithme automatique, permettant une investigation détaillée des caractéristiques du LLJ dans la région durant les périodes estivales de 2022 et 2023. Les jets ont été détectés 50 à 70 % des nuits examinées, souvent simultanément sur les deux sites urbain et suburbain, soulignant l'étendue spatiale régionale du LLJ. Les jets apparaissent généralement au coucher du soleil, avec une durée moyenne d'environ 10 heures. De nombreux jets ont montré des signatures d'évolution temporelle indiquant que le mécanisme d'oscillation inertielle joue un rôle dans le développement des jets, caractérisé par une rotation horaire de la direction du vent, une accélération rapide et une décélération plus lente. De plus, selon la hauteur du noyau et la vitesse du vent, le LLJ induit une turbulence mécanique jusqu'à la couche de canopée urbaine et module l'intensité de l'Îlot de Chaleur Urbain (ICU), c'est-à-dire la différence de température spatiale entre la ville et les espaces ruraux environnants. Cette étude démontre comment les observations par LD en milieu urbain fournissent des informations précieuses sur les processus proches de la surface pertinents pour la santé humaine et environnementale
Simulation of deuterium and hydrogen loss on Mars by thermal, photochemical and solar wind processes
No full textInternational audienceThe D/H ratio is a key parameter to understand the atmospheric evolution of a planet. On Mars a D/H ∼ 5 times larger than the ratio on Earth is measured. This large ratio can be explained by a preferential escape of the hydrogen compared to the deuterium due to its lower mass. However, while the thermal escape (Jeans escape) is strongly mass dependent other non-thermal processes are less mass dependent and would impact the time needed to fractionate the water from the terrestrial value to the current value. In this work, we will present new simulations obtained by coupling 3 models to estimate the hydrogen and deuterium escape. The 3D Martian Planetary Climate Model (PCM-Mars) is used to compute the Jeans escape rate of D, H, H2 and HD, as well as the ion and neutral densities below the exobase are computed using at spring equinox. A 3D exospheric model is used to compute the escape rate of H and D due to photochemical reactions in the ionosphere and the escape rates of H, D, H2 and H2 induced by the collisions between the hot oxygen and these atmospheric species. Finally, a 3D hybrid model of the Martian induced magnetosphere is used to compute the escape of H+ and D+ produced by photoionization and charge exchange with the solar wind protons. The contribution of each process and the derived fractionation factor will be presented and discussed
Modélisation hybride de l'élimination de l'azote par biofiltration à l'aide de données opérationnelles haute fréquence
No full textInternational audienceIn this research, a parallel hybrid model is presented for the simulation of nitrogen removal by submerged biofiltration of a very large-size wastewater treatment plant. This hybrid model combines a mechanistic and a machine learning model to produce accurate predictions of water quality variables. The models are calibrated and validated using detailed and quality-controlled operational data collected over a period of 3.5 months in 2020. The mechanistic model is a modified activated sludge model that describes the biological, physical and chemical processes taking place in a biofilm reactor based on the domain knowledge of these processes. A three-layer feed-forward artificial neural network with a rectified linear activation function that aims to reduce the mechanistic model's residual error and then correct its output. The results show how the hybrid model outperforms and significantly reduces the size of the mechanistic model's prediction errors of the effluent nitrate concentration from a relative mean error of 12% (mechanistic model) to 2% (hybrid model) during training. The error on nitrate simulations increases to 8% during hybrid model testing, still significantly lower than the error of the mechanistic model. These results support future operational applications of hybrid biofilm models, such as in digital twins.Dans cette recherche, un modèle hybride parallèle est présenté pour la simulation de l'élimination de l'azote par biofiltration submergée dans une station d'épuration de très grande taille. Ce modèle hybride combine un modèle mécaniste et un modèle d'apprentissage automatique afin de produire des prédictions précises des variables de qualité de l'eau. Les modèles sont calibrés et validés à l'aide de données opérationnelles haute fréquence collectées sur une période de 3,5 mois en 2020. Le modèle mécaniste est une version modifiée du modèle des boues activées qui décrit les processus biologiques, physiques et chimiques se déroulant dans un réacteur à biofilm, en s'appuyant sur les connaissances du domaine. Un réseau de neurones artificiels à trois couches avec une fonction d’activation linéaire rectifiée est utilisé pour réduire l'erreur résiduelle du modèle mécaniste et corriger ensuite sa sortie. Les résultats montrent que le modèle hybride surpasse le modèle mécaniste et réduit de manière significative l'erreur de prédiction de la concentration en nitrate à la sortie, passant d'une erreur moyenne relative de 12 % (modèle mécaniste) à 2 % (modèle hybride) durant l'entraînement. L'erreur sur les simulations de nitrate augmente à 8 % lors du test du modèle hybride, mais reste nettement inférieure à celle du modèle mécaniste. Ces résultats soutiennent les futures applications opérationnelles des modèles hybrides de biofilm, notamment dans les jumeaux numériques