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La décision d’installation de point de recharge pour véhicule électrique en copropriété : le paradoxe du droit à la prise à l’aube de la diffusion en masse des véhicules électriques
No full textInternational audienceL’électrification de la mobilité individuelle est l’un des moyens de répondre aux impératifs environnementaux de la transition énergétique dans le domaine des transports, qui est le secteur le plus émetteur de dioxyde de carbone en France. La diffusion de véhicules électriques est de ce fait un des éléments promus par les politiques publiques, en remplacement des véhicules conventionnels (bonus écologique). Cet article s’attache à identifier comment les acteurs concernés aboutissent à la décision d’équiper une copropriété d’un point de recharge pour véhicule électrique. Nous montrerons comment s’organise le processus d’installation d’une infrastructure de recharge pour VE en copropriété, en examinant les positionnements des acteurs en présence et les étapes traversées par les copropriétaires demandeurs d’une installation ; puis, distinguant les différents chemins sociotechniques empruntés pour cette infrastructure, nous montrerons ce qui guide le choix pour l’un plutôt que l’autre. Nous verrons que la configuration technique de la recharge en copropriété est corrélée à de complexes stratégies d’installation qui dépendent elles-mêmes du positionnement des trois types d’acteurs en présence
Maximiser l’impact des actions dans la gestion de la transition hydrique
No full textInternational audienc
Fertilizing potential of nitrogen in human excreta across diverse countries and food systems
No full textInternational audienceAbstract Human excreta represent a significant but underutilized source of nitrogen (N) for agriculture. Few studies have quantified the full fertilizing potential of human excreta across national contexts, or under a range of diverse food systems. This study provides the first systematic assessment of the potential contribution of N in human excreta to current cropland fertilization in a wide range of countries, covering 80% of the global population. Using food supply and demographic data, we estimate N in human excreta for each country and compare it to current cropland total N inputs, including synthetic fertilizers, manure, biological fixation, and atmospheric deposition. Assuming a 100% recovery rate of human excreta to estimate an upper-bound potential, under the current situation, we find that human excreta (37 MtN at the global scale) could provide 15–30% of current cropland N inputs in most countries, 30–50% in sub-Saharan Africa, and over 50% in major agricultural importers (e.g. Japan, Korea, Algeria). In contrast, large agricultural exporters with high external inputs, such as Argentina or the United States, show lower potential (5–10%). For the whole world, the rate is 20%. For most countries, N excreted by humans is also of the same order of magnitude as (and often superior to) livestock manure currently applied to croplands. In addition to an analysis of the current situation, we assess how improved food system efficiency—via more vegetarian diets, reduced losses and increased manure recycling thanks to better coupling of husbandry and crop cultivation—could affect the potential contribution. Under deeply transformative agro-ecological scenarios, theglobal contribution of human excreta to N fertilization could exceed 30%.This work focuses on maximum potentials; future research should focus on realisticrecovery rates (<100%) and adjust our results accordingl
Thermally-induced long-term behavior of energy piles under inclined load in saturated clay
No full textInternational audienceThermally-induced long-term behaviors, such as the ratcheting phenomenon, have been observed in vertically and horizontally loaded energy piles under thermal cycling. However, whether this phenomenon occurs in inclined loaded piles and the underlying mechanisms remain unclear, especially considering the combined effect of horizontal and vertical loads on pile–soil interaction. This study employed laboratory model tests and numerical simulations to investigate the long-term behavior of the energy pile under an inclined load in saturated clay. The experiment involved constant vertical loading of 100 N, 15 thermal cycles with temperature changes of ±3.5 °C, and various horizontal loads (35, 71, and 109 N, corresponding to horizontal displacements of 4%, 7%, and 12% of pile diameter, respectively). Due to the scale effect, all acquired data have been normalized to facilitate better use in the qualitative thermomechanical analysis of energy piles. Measurements and simulations demonstrated that the ratcheting phenomenon is evident in inclined loaded energy piles. Cyclic thermal loading caused irreversible vertical and horizontal displacements of the pile head, with an accumulation rate decreasing as thermal cycles increased. The analysis suggests that the ratcheting phenomenon may be induced by variations in load transfer caused by the energy pile–soil interaction under long-term thermal operations. These findings provide valuable insights into the long-term performance and design considerations for energy piles subjected to inclined loads
La plaine alluviale de la Bassée : comment re-penser les solidarités au travers de l’eau et de la biodiversité?
No full textInternational audienceLa Bassée is a flood plain of the Seine River located in two départements (Aube and Seine-et-Marne), comprising several conurbations and stretching from the Aube-Seine confluence upstream (Romilly sur Seine) to the Seine-Yonne confluence downstream (near Montereau-Fault-sur-Yonne). This area, where the hydrogeological functioning of the river’s major bed has been heavily impacted by the development projects, is at the crossroads of a number of issues (alluvial deposits exploitation, drinking water supply of the Paris metropolitan area, flood prevention for downstream areas, etc.). La Bassée is therefore an area contributing to the resilience of other areas downstream.This independency raises questions about the capacity of this territory and the related stakeholders to develop their own strategy and to build a a territorial project that could be more autonomous. The aim of our research was therefore to explore the logics of solidarity and negotiation between stakeholders and their vision of the desired biodiversity (through different objects: water, preservation of species, creation of a new nature reserve). The question of solidarity within the Bassée-Voulzie area, and between it and downstream areas (particularly the Paris metropolis), has long been a source of frustration linked to the exploitation of water and sediment resources and the subsequent development of aquatic environments. In this paper, we examine some of the scenes in which a variety of stakeholders meet and compare their visions of the territory. We highlight how projects are negotiated at scales ranging from the upstream Seine basin to river branches or water reservoirs, and to what extent these multiple negotiations offer a perspective for joint and environmental management of the river.La Bassée est une vaste plaine alluviale de la Seine à cheval sur deux départements (Aube et Seine-et-Marne), comptant plusieurs intercommunalités et qui s’étend de la confluence Aube-Seine en amont (Romilly sur Seine) et la confluence Seine-Yonne en aval (à la hauteur de Montereau-Fault-sur-Yonne). Ce territoire dont le fonctionnement hydrogéologique du lit majeur a été très fortement impacté par les aménagements du fleuve est à l’intersection de plusieurs enjeux (prélèvements d’alluvions et d’eau potable pour l’approvisionnement de la métropole parisienne, prévention des inondations des territoires situés à l’aval…). La Bassée est donc un territoire qui participe à la résilience d’autres territoires à l’aval. Se posent ainsi des questions sur la capacité de cet espace à construire une logique d’action propre et à repenser ses (inter)dépendances pour ne pas être seulement le réceptacle de projets venus d’ailleurs. L’objectif de notre recherche était donc d’explorer les logiques de solidarité, de négociations entre les acteurs et les visions et la place accordées à la biodiversité (via différents objets : eau, préservation des espèces, constitution d’une nouvelle réserve naturelle). La question des solidarités au sein du territoire de la Bassée-Voulzie, ainsi qu’entre celui-ci et les territoires aval (et particulièrement la métropole parisienne), nourrit depuis longtemps des frustrations liées à l’exploitation des ressources en eau et en sédiments et à l’aménagement consécutif des milieux aquatiques. En analysant quelques unes des scènes au sein desquelles des acteurs pluriels se rencontrent et confrontent leur vision du territoire, nous mettons en lumière la manière se négocient des projets à des échelles allant du bassin amont de la Seine au bras de rivière ou au plan d’eau et jusqu’à quel point ces négociations multiples offrent une perspective de gestion commune et environnementale du fleuve
Reconstruction des flux de trafic à partir de données collectées limitées
No full textWe propose an efficient method for reconstructing traffic density with low penetration rate of probe vehicles. Specifically, we rely on measuring only the initial and final positions of a small number of cars which are generated using microscopic dynamical systems. We then implement a machine learning algorithm from scratch to reconstruct the approximate traffic density. This approach leverages learning techniques to improve the accuracy of density reconstruction despite constraints in available data. For the sake of consistency, we will prove that, if only using data from dynamical systems, the approximate density predicted by our learned-based model converges to a well-known macroscopic traffic flow model when the number of vehicles approaches infinity
Endogenous barriers to learning
No full textInternational audienceBuilding on the idea that lack of experience is a source of errors but that experience should reduce them, we model agents' behavior using a stochastic choice model (logit quantal response), leaving endogenous the accuracy of their choices. In some games, higher accuracy leads to unstable logit-response dynamics. Starting from the lowest possible accuracy, we define the barrier to learning as the maximum accuracy which keeps the logit-response dynamic stable (for all lower accuracies). This defines a limit quantal response equilibrium. We apply the concept to centipede, travelers' dilemma, and 11-20 money-request games and to first-price and all-pay auctions, and discuss the role of strategy restrictions in reducing or amplifying barriers to learning
Temperature dependence of the bond strength in externally bonded CFRP systems for concrete structures
No full textInternational audienceThis study investigates the influence of temperature on the mechanical properties of carbon fibre-reinforced polymer (CFRP) strengthening systems externally bonded to concrete substrates. This study examined six different CFRP systems, including four pultruded CFRP plate systems and two sheet systems, which are representative of the products currently used in the French market. The CFRP concrete specimens were tested at different temperatures in two laboratories under double-lap shear or single lap-shear test configurations, representing 138 test samples. The tests were conducted at room temperature and at several other temperatures in the range T g -20 • C to T g + 15 • C, where T g is the glass transition temperature of the epoxy adhesive or matrix. As the test temperature increases, results showed a slight increase in the maximum load capacity of the bond in the range of T g -15 • C or T g -10 • C for some CFRP systems) related to polymer softening and stress redistribution along the lap joint. For most systems, the characteristic values of load capacity and bond strength remained above or near their initial levels (at 20 • C) for test temperatures up to the polymer but declined sharply beyond this limit. These experimental results were then compared with the calculation method outlined in Appendix J of Eurocode 2 focusing on externally bonded reinforcements, demonstrating that this design method can be safely applied up to T g -10 • C for all systems and even higher for certain ones. Therefore, a temperature limit of T g -10 • C is recommended for serviceability purposes. However, the testing procedure allow to assess a higher temperature limit if the system demonstrates an acceptable variation in the characteristic bond strength
Murissement de mousse liquide en milieu confiné
No full textInternational audienceThe coarsening dynamics are primarily governed by the reduction of interfacial energy, leading to an increase in the characteristic length scale within two-phase systems. This phenomenon plays a crucial role in the stability and aging of densely packed particle structures, commonly found in materials such as alloys, foams, emulsions, and supersaturated solutions. Previous studies have demonstrated that properlyconfining these particles can induce a phenomenon known as anti-coarsening, ultimately resulting in a specific arrangement where each pore contains a single particle, marking the cessation of coarsening. In this work, we quantitatively investigate the coarsening behavior of liquid foam confined within the pores of a spherical bead packing, where the bead size is adjusted to control the degree of confinement. Our findings indicate that, aside from the final state characterized by the arrest of coarsening, reducing the available space accelerates the coarsening process. This unexpected behavior arises fromthe interplay between the liquid trapped by the grains and the effective liquid volume fraction within the porous network.Dans les systèmes biphasiques, le processus appelé murissement est entraîné par la réduction de densité d’énergie interfaciale, ce qui s’accompagne d’une augmentation de l’échelle de taille des domaines. De manière générale, il joue un rôle crucial dans la stabilité et le vieillissement des assemblées denses de particules, que l’on retrouve couramment dans les alliages, les mousses, les émulsions et les solutions sursaturées. Il a été démontré précédemment que, lorsqu’elles sont correctement confinées dans un milieu poreux, des assemblées de bulles subissent le phénomène dit d’anti-murissement, conduisant à uneconfiguration où une bulle occupe chaque pore, associée à l’arrêt du murissement. Dans cette étude, nous explorons quantitativement la dynamique du murissement d’une mousse liquide confinée dans les pores d’un empilement de billes sphériques, où la taille des billes a été ajustée pour modifier le degré de confinement. Nous observons que, hormis la configuration finale associée à l’arrêt du murissement, plus le système est confiné, plus il murit rapidement. Ce comportement inattendu résulte de l’interaction entre le liquide piégé par les grains et la fraction volumique effective du liquide dans la mousse situéeau coeur des pores