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Shaping the Mediterranean Gateway to Europe: Undersea Cables, Data Centers, and the Politics of Digital Growth
No full textInternational audienceBetween 2018 and 2024, Digital Realty constructed or initiated plans for four data centers with a combined capacity of 87 MW at the Marseille-Fos Port, an industrial port located on the northern coast of Marseille, France. The port promoted the development of digital infrastructure as a strategy to diversify its revenue streams amid a significant decline in oil exports, while also seizing the opportunity presented by the city’s rapidly growing status in global data exchanges. Over the past decade, Marseille has ascended from 44th to 5th place among the world’s most connected cities. This new status has garnered particular interest from the port's regulatory body, the French government, which aims to transform the site into a strategic asset for enhancing national digital sovereignty.This infrastructural growth is profoundly reshaping the relationship between the port and its many neighbors. It is viewed as an opportunity for a maritime nature park to redirect undersea cables that have traditionally traversed its protected area. However, it has also sparked outrage among citizens who perceive data centers as appropriating energy that should have been allocated to powering polluting maritime activities. Additionally, local elected officials are concerned about the potential development of large data centers on their territory, especially as the port has no remaining available land.This communication will document the contested politics surrounding the development of digital infrastructures in Marseille, analyzing how these conflicts challenge the territorial roles of an industrial harbor in the context of climate change
Parametric shape optimization of flagellated microswimmers using Bayesian techniques
No full textInternational audienceUnderstanding and optimizing the design of helical microswimmers is crucial for advancing their application in various fields.The Boundary Element Method (BEM) is used to simulate the dynamic [1]. Due to the complexity of our model, we focus on parametric shape optimization. We employ the Free-Form Deformation (FFD) technique [2], which provides a sufficiently complex admissible shape space. This is integrated with the Scalable Constrained Bayesian Optimization (SCBO) method [3], ideal for high-dimensional constrained optimization problems
Quels apports de la notion de milieu à la conception ? Programme de recherche sur la notion de milieu en conception
No full textInternational audienceCe poster donne un aperçu d'un programme de recherche mêlant les théories de la conception et la notion de "milieu". Il présente des enjeux empiriques liés à ces questions, rappelle les contributions d'auteurs comme Uexküll, Simondon et Leroi-Gourhan aux liens entre milieu et conception, formule une question de recherche, propose un modèle de milieu à partir de la théorie CK et donne des perspectives de recherche théoriques et empiriques
The Freight Transportation Game: Operational Challenges for Carriers in Online Spot Market Platforms
No full textInternational audienceIn the freight transport spot market, carriers face several challenges, including handling small-sized loads, managing short lead times, and dealing with uncertainties that can disrupt their existing networks and capacity. In this context, auction platforms assist carriers in developing strategies to maintain productivity and service levels. This paper introduces the freight transportation game, an online auction-based platform specifically designed for the freight spot market. The game equips players, acting as carriers, with tools to develop transportation strategies, optimize routes, and propose competitive rates to maximize profits. Players engage in decision making and competition, with key performance indicators evaluating their decisions. The game includes two scenarios; the first helps students understand the operational challenges that carriers face in spot market auctions, whereas the second encourages cooperation to enhance performance and overcome obstacles. Designed for a three-hour session, the game can be integrated into courses on supply chain management or transportation systems. The practical learnings for students from the game include understanding the complexity of constructing transport plans, recognizing the challenges of using online auction-based platforms, and experiencing the difficulties of managing spot market requests despite their benefits
Assessing performance of a power plant
No full textThe disclosure notably relates to a computer-implemented method for assessing performance of a power plant. The power plant comprises a solar field system and a storage system. The method comprises providing one or more sets of inputs. Each set of inputs represents a respective architecture of the power plant. The method further comprises computing, for each set of inputs, by a computer system and based on the set of inputs, output data including one or more yearly indicators. For each set of inputs, the computing comprises, for each day of a set of days, optimizing a schedule for the power plant and computing daily indicators for the day. The computing further comprises, for each set of inputs, determining the one or more yearly indicators based on the computed daily indicators. The method forms an improved solution for assessing performance of a power plant
J-NeuS: Joint field optimization for Neural Surface reconstruction in urban scenes with limited image overlap
No full textReconstructing the surrounding surface geometry from recorded driving sequences poses a significant challenge due to the limited image overlap and complex topology of urban environments. SoTA neural implicit surface reconstruction methods often struggle in such setting, either failing due to small vision overlap or exhibiting suboptimal performance in accurately reconstructing both the surface and fine structures. To address these limitations, we introduce J-NeuS, a novel hybrid implicit surface reconstruction method for large driving sequences with outward facing camera poses. J-NeuS cross-representation uncertainty estimation to tackle ambiguous geometry caused by limited observations. Our method performs joint optimization of two radiance fields in addition to guided sampling achieving accurate reconstruction of large areas along with fine structures in complex urban scenarios. Extensive evaluation on major driving datasets demonstrates the superiority of our approach in reconstructing large driving sequences with limited image overlap, outperforming concurrent SoTA methods
Résilience à température ambiante et à température cryogénique d'un acier inoxydable 316L élaboré par fabrication additive arc-fil
No full textInternational audienceIn this study, the impact toughness behavior of wire-arc additively manufactured 316L stainless steel (WAAM 316L) was characterized at room temperature and at -193 ◦C. Microstructure – toughness relationships were determined, as well as the influence of recrystallization on microstructural evolution and impact properties. At the stress-relived state, WAAM 316L exhibited a ductile fracture and an impact toughness of 139 ± 10 J/cm2 at room temperature, whereas a partially brittle fracture was obtained at -193 ◦C leading to a low impact toughness of 28 ± 10 J/cm2. Recrystallization and homogenization heat treatment induced a significant increase in impact toughness both at room temperature (+60 %) and at -193 ◦C (+475 %). As in other additively manufactured 316L, oxide particles appeared to be the microstructural feature controlling ductile fracture of WAAM 316L and the cause of its low impact toughness compared to conventionally processed 316L. Brittle fracture observed at -193 ◦C occurred by cleavage of the δ-ferrite domains. A comparison of the results obtained with WAAM 316L with those reported by the literature for LPBF 316L allowed to identify the localization of oxide particles as a key factor in determining the relevance of recrystallization heat treatments, regarding the fracture behavior
Modélisation et caractérisation d’échangeurs membranaires avec récupération de chaleur intégrée: Applications á la distillation membranaire
No full textMembrane distillation is a promising technology to address the increasing global demand for freshwater while reducing reliance on conventional energy-intensive processes. However, its industrial uptake remains limited due to unresolved technical challenges. This work, carried out within an industrial collaboration, focused on overcoming these barriers through the design of an innovative air-gap membrane distillation system with integrated heat recovery. The system employed flat-sheet modules and flat-jet nozzles to enhance heat and mass transfer via solution atomization and improved fluid distribution, while also enabling the use of cost-effective non-woven fiber membranes. A coupled heat and mass transfer model was developed and validated through experiments with a laboratory-scale prototype. The prototype achieved heat transfer densities of 0.6–1.4 kW/m² and distillate fluxes of 0.9–2 kg/m²·h at 55–80 °C, while ensuring >99% rejection of salts, ions, and organic compounds, including highly conductive oil-produced water. Model validation enabled the evaluation of systemic integration across three industrial use-cases, demonstrating the versatility and economic competitiveness of the technology under varied conditions, particularly when renewable or waste heat was available. Finally, the successful deployment of a semi-industrial pilot for stillage cooling and water recovery confirmed the scalability and operability of the system beyond laboratory conditions, while highlighting pathways for further optimization, notably increasing distillate production.La distillation membranaire est une technologie prometteuse pour répondre à la demande croissante en eau douce tout en réduisant la dépendance aux procédés conventionnels énergivores. Toutefois, son déploiement industriel reste limité en raison de verrous technologiques persistants. Ce travail, mené dans le cadre d’une collaboration industrielle, a porté sur la conception d’un système innovant de distillation membranaire avec cavité d’air intégrant récupération de chaleur. Le système utilise des modules à plaques planes et des buses à jet plat afin d’améliorer les transferts de chaleur et de masse par atomisation et meilleure distribution du fluide, permettant également l’emploi de membranes économiques en fibres non tissées. Un modèle couplé de transferts de chaleur et de masse a été développé et validé par un prototype expérimental. Celui-ci a atteint des densités de transfert thermique de 0,6–1,4 kW/m² et des flux de distillat de 0,9–2 kg/m²·h à 55–80 °C, avec un taux de rétention supérieur à 99 % pour les sels, ions et composés organiques, y compris des eaux de production hautement conductrices. La validation du modèle a permis l’évaluation de trois cas d’usage industriels, confirmant la polyvalence et la compétitivité économique de la technologie, notamment lorsqu’elle est couplée à des sources de chaleur renouvelable ou fatale. Enfin, la mise en place réussie d’un pilote semi-industriel pour le refroidissement de flegmasses et la récupération d’eau a démontré la transférabilité et l’opérabilité du système à plus grande échelle, tout en ouvrant des perspectives d’optimisation, en particulier l’augmentation de la production de distillat
Panel on "The Future of Energy Markets, Demand Response, and Grid Services"
No full textInternational audienc
Oxygen reactivity in aquifer storage of compressed air and biomethane-natural gas blends: from pilot to modeling
No full textInternational audienceThe air containing 8 mol% oxygen was injected during 3 years as a cushion gas into a natural gas reservoir, a carbonate-cemented sandstone aquifer located in the Paris Basin (France). 10-year survey showed that: O2(g) was fully depleted several months after injection completion, meanwhile CO2(g) was detected around 2–6 mol%; the pH decreased from 8 to 6, while reducing conditions shifted to mildly oxidizing ones with increasing concentration of sulfates in equilibrium with gypsum. 3 years after injection completion, the pH gradually returned to its near initial state and sulfates were reduced by 2 to 3 times. Release of trace metals (Ba, Cu, Pb, Zn) during and after the test was also studied. Multiphase reactive transport modeling based on these field data [1] allowed to reproduce 1/ the full depletion of the injected O2(g) due to pyrite oxidation, 2/ leading to acidity production and dissolved sulfates, 3/ acidity buffering by calcite dissolution, 4/ followed by gypsum precipitation and CO2(g) exsolution. This field-based model was used to study the geochemical impact of injecting a gas mixture with biomethane containing oxygen into two deep aquifers. Multiple scenarios with O2 content up to 1000 ppm in the injected gas were modeled to assess the resilience of geological storage to oxygen presence and predict the evolution of stored gas and formation water quality. Multiphase reactive transport simulations [2] revealed that gas injection caused acidification of the solution, lowering from pH 8 to 6. However, the primary acidification factor in this case was the presence of 1 mol% CO2(g) in the gas mixture. The model demonstrated that the pH buffering capacity of sandstone aquifers relied on 1/ calcite dissolution, 2/ feldspar dissolution and 3/ clay dissolution and sorption capacity. These buffering mechanisms were effective for oxygen contents ranging from 10 to 1000 ppm. More locally than the pH impact, redox conditions became mildly oxidizing. Model indicated that gas injection could induce minimal but long-term change in mineralogy without significantly affecting porosity. Overall, the gas quality was preserved in both sandstone reservoirs.[1] Sin et al., 2023 http://dx.doi.org/10.1016/j.scitotenv.2023.161657 [2] Banc et al., 2024 https://doi.org/10.1016/j.jgsce.2024.20538