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Foules d’Olivia Grandville. Un projet participatif aux confins des tensions du champ chorégraphique
No full textInternational audienceTandis que les projets participatifs se multiplient sur scène, la pièce Foules d’Olivia Grandville agit comme un révélateur des tensions qui traversent le monde artistique : entre ambition esthétique et bricolage organisationnel, promesse démocratique et risque d’inégalités, reconnaissance institutionnelle et possible instrumentalisation politique
Reading the Future of Oil: A Noncausal Approach to Supply News Shocks
No full textThis paper proposes a new strategy to identify oil supply news shocks by combining a Bayesian noncausal structural VAR with a Max-Share approach. The framework jointly resolves the problems of non-fundamentalness and recoverability that undermine standard (proxy) SVAR methods. Exploiting non-Gaussianity in a multivariate Student−t specification, we recover structural shocks from a two sided moving average representation and isolate the expectation driven component of oil supply innovations without external instruments. Applied to global oil market data, the model supports a non fundamental representation and detects anticipatory price and inventory movements consistent with rational expectations storage behavior. The identified shocks explain a substantial fraction of real oil price fluctuations, notably in the late 1970s–1980s and during the 2014–15 collapse, while the COVID-19 episode is predominantly demand driven. Decomposing global supply shows that these shocks are primarily OPEC-driven and generate stagflationary responses in output and inflation, underscoring the central role of expectations in oil market dynamics
Microwave-assisted desorption of CO<sub>2</sub> from ethanolamine solvent in a porous hollow fiber membrane - numerical modeling
No full textInternational audienceIn our previous work, microwave regeneration of 30 wt. % ethanolamine solvents in a hollow fiber gas-liquid contactor was studied. In this system, the solvent was heated by microwaves as it traversed a microwave applicator while passing through the lumen of the hollow fiber. Experimental results do not provide insight into the operation of microwave regeneration. The aim of this study is therefore to develop a model to simulate the microwave solvent regeneration in the single fiber system.The numerical approach is based on coupling 3D microwave heating of solvent flow, and 1D chemical desorption of CO2 applicable to non-isothermal conditions along the fiber. The model was successful in reproducing with reasonable accuracy the global desorption data from the regeneration experiments, assuming a low wetting fraction of the membrane. The effects of operating conditions were explored: results show that increasing the solvent flow rates induces higher temperature gradients at the boundary of the fiber lumen thus increasing desorption rates. It has been found that increased fiber radius leads to better desorption rates at the expense of lowering the interfacial surface density. On another note, numerical results show that isothermal regeneration performs better than microwave mode although the latter is able to outperform where hotspots persist along the fiber. With regards to flow configurations during microwave regeneration, counter-current mode performed better than co-current one: the sweeping gas in the former mode passes from the hot solvent side to the cold solvent side which encourages reabsorption of the desorbed CO2
Differing responses of functional and taxonomic waterbird diversity to vegetation height and water level variation in a coastal wetland
No full textInternational audienceThe conservation of wetland biodiversity is a major global issue. In anthropogenic landscapes, it requires the identification of environmental conditions and management practices that sustainably maintain the diversity of the communities. We carried out a six-year survey over 18 sites (78 ha) in the Marais Breton, lowland grazing marshes on the western coast of Europe in France. We tested the influence of the spatio-temporal dynamic of vegetation heights, water depth and the proportion of flooded areas on the taxonomic and functional diversity of wading birds and ducks at the site scale. Taxonomic diversity was enhanced by higher spatial heterogeneity of water level and reduced by higher spatial heterogeneity of vegetation height. In sharp contrast, functional diversity was not influenced by spatial heterogeneity of water level and increased with spatial heterogeneity of vegetation height. Additionally, the effect of the spatio-temporal heterogeneity of water level and vegetation height was guild-dependent. Based on our results we encourage a management at the landscape scale integrating multiple land ownerships to promote a taxonomic and functional diversity rather than at the site scale only
Markov Decision Process for Mixed-Model Assembly Line design under process time uncertainty
No full textInternational audienceThe industry is increasingly confronted with the challenge of process duration uncertainty in production systems. These variations are particularly problematic for manufacturers that utilize Multi-Manned Mixed-Model Assembly Lines, as they can cause significant disruptions that may stop the production line. Our study explores the benefit of walking workers to dynamically adjust the workforce in response to unexpected variations in process durations at different stations, a common scenario in the automotive industry. We model the dynamic workforce assignment decision as a Markov Decision Process, and this MDP accounts for uncertainties in process times, and it incorporates dynamic task assignment and workers' movements. This MDP is subsequently translated into a linear program that we integrate into a higher-level Mixed-Integer Linear Programming model responsible for dimensioning the workforce and selecting equipment in the station. This approach results in the creation of assembly lines designed to be resilient in the face of unexpected variations in task process durations.To deal with scalability issues, we employ the Benders decomposition algorithm. The paper also presents a validation with data from a car manufacturer that reinforces the practical applicability of our methodology. Additionally, we provide managerial insights on effectively managing process time uncertainty in automotive production systems, empowering decision-makers with optimization strategies, cost-reduction approaches, and resilience-building techniques to enhance the performance and reliability of Mixed-Model Assembly Lines
Reprendre la politique aux élites : la solidarité radicale contre les privilèges
No full textOlúfẹ́mi O. Táíwò, « Being-in-the-Room Privilege : Elite Capture and Epistemic Deference », The Philosopher, 202
Encode the Cake and Eat it Too: Controlling computation in type theory, locally
No full textInternational audienceProof assistants based on dependent type theory such as Agda, Lean and Rocq identify objects up to computation during proof checking. This takes away some of the proof burden from the user and even provides a way to get very efficient automation. Recently, Agda and Rocq have been extended to support user-defined computation. While they already prove very useful, user-defined computation rules are global: once they are added, they are here to stay. Importing a development that makes use of those rules then means relying on them, whether we want it or not, which can lead to unwanted incompatibilities. We design LRTT, a type theory with support for local abstraction over user-defined computation rules. This takes the form of a prenex quantification at the definition level. This quantification is supplemented with the possibility to provide one or several instantiations that verify the equations definitionally. We show that a procedure inlining definitions abstracting over definitional equality is possible, in the style of monomorphisation or of C++ templates. In the process we get a conservativity result over more conventional Martin-Löf type theories. There are several benefits to such a system. First, it provides encapsulation for user-defined computation rules, which is important to avoid unwanted bad interactions and limits the scope in which invariants of type theory (such as termination, confluence, type preservation and consistency) are broken. Second, abstraction lets users factorise code that crucially relies on definitional equality, as well as hide implementation details that are irrelevant in some settings. Finally, it gives a way to encode certain features without paying the price of the encoding. We showcase such examples in a prototype implementation as an extension of the Rocq Prover. Additionally, all the results in this have been formalised in Rocq
Measurements of the proton-induced reaction 155Gd(p,n)155Tb at energies between 7 and 26 MeV with highly-enriched 155Gd targets
No full textInternational audienceBackground The need for new medical radionuclides continues to grow as treatments become more personalised. Terbium-155, a gamma emitter, is an appealing isotope that could be used for Single Photon Emission Computed Tomography (SPECT). Since it belongs to the Terbium quadruplet, it could be coupled with other Tb isotopes to form a theranostic pair. However, it is currently not accessible in sufficient quantities with an acceptable radionuclidic purity. An investigation of the excitation function of the nuclear reaction 155Gd(p,n) over an energy range accessible to most medical cyclotrons is relevant for optimizing 155Tb production. For the first time, we report the measurements of this reaction with highly enriched (> 99.0%) 155Gd targets. Methods Pure 155Gd targets, with isotopic enrichment better than 99%, have been produced using the highperformance electromagnetic separator SIDONIE at IJClab, Orsay, France. Proton activation measurements have been performed using two different cyclotrons and a linear accelerator (linac). Results The full excitation function of 155Gd(p,n)155Tb has been obtained over the 7-26 MeV range. All 18 measured cross-sections are consistent with each other, without the need of any renormalization. All the obtained data were compared with already published results and clearly show a maximum production at 11 MeV, with a cross section of 500 mb. Conclusion Experimental data indicates excitation function maximum around 11 MeV for the studied energy range, and cross sections are greater when target purity in 155Gd is higher
Entwicklung der kritischen Fähigkeiten von Schüler*innen: Vom Geschichtsunterricht zum Umgang mit aktuellen Ereignissen
No full textInternational audienc
Efficient time-dependant fatigue reliability assessment accounting for material variability in steel structures
No full textInternational audienceFor steel structures with highly variable number of cycles to failure and when the load history is the output of a complex stochastic process, assessing fatigue damage with time is challenging. In this article, non-linear accumulation damage model available in literature is considered. With this model, the history of loading, that is to say the order or cycles, is taken into account. Using this model to estimate probability of failure requires great computational costs. In this article, two numerical strategies to reduce these costs are proposed: by creating kriging-based meta-models and dening relevant enrichment procedures, an estimation of the instantaneous probability of failure is computed. In addition, upper and lower bounds of the probability of failure are derived and enable to assess the quality of the simulation. Numerical illustrations are given on a plate with material variability and 10 000 load cycles