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Contamination of wines by undesired microorganisms may lead to significant deterioration of the final product. To combat these problems, sulfur dioxide (SO2) is the most widely used additive for its antiseptic and antioxidant properties. However, the limitation of chemical inputs in wines is one of the major concerns of consumers and producers. Existing physical stabilization processes (flash pasteurization, tangential filtration) have disadvantages, such as their energy cost or their complex maintenance. Two innovative processes to ensure the microbiological stabilization of wines as an alternative to conventional processes are studied: ultraviolet radiation (UV-C) and ohmic heating. UV-C radiation (100 to 280 nm) is known for its germicidal effect and already applied in the treatment of water and surfaces. However, absorbent liquids, such as wine, strongly limit the penetration depth of the radiation and hence the efficiency of the process. A helical UV-C reactor was developed, based on the hydrodynamic properties of Dean vortices, to improve the efficiency and homogeneity of the treatment. The stabilization performance was validated for the first time as an alternative to the SO2 mutage of sweet wines and before the bottling of finished wines. Moreover, the chemical and sensory analyzes carried out on the treated wines showed no impact on the quality of wines. Ohmic heating is used in this study as a method of thermal stabilization of musts and wines. During the passage of a current through a material having an electrical resistance, the electrical energy is transformed into thermal energy. The heat is then generated inside the material to be treated. The results of this work showed for the first time that heating rate and homogeneity of ohmic heating allow an effective stabilization of musts and wines without affecting their quality.; La contamination des vins par des microorganismes non désirés peut entraîner une dégradation importante du produit. Pour lutter contre ces problèmes, le dioxyde de souffre (SO2) est l’additif le plus utilisé actuellement pour ses propriétés antiseptiques et antioxydantes. Cependant, la limitation des intrants chimiques dans les vins est une des préoccupations majeures des consommateurs et producteurs. Les procédés de stabilisation physiques existants (flash pasteurisation, filtration tangentielle) présentent quant à eux des inconvénients, tels que leur cout énergétique ou leur maintenance complexe. Deux procédés innovants permettant d’assurer la stabilisation microbiologique des vins en alternative aux procédés classiques sont étudiés : le rayonnement ultraviolet (UV-C) et le chauffage ohmique. Les rayonnements UV-C (100 à 280 nm) sont connus pour leur effet germicide et déjà appliqués dans le traitement de l’eau et des surfaces. Cependant les liquides absorbants, tels que le vin, limitent fortement la profondeur de pénétration du rayonnement et donc l’efficacité du procédé. Un réacteur UV-C hélicoïdal a été développé, basé sur les propriétés hydrodynamiques des vortex de Dean, pour améliorer l’efficacité et l’homogénéité du traitement. Les performances de stabilisation ont été validées pour la première fois en alternative au mutage par SO2 de mouts liquoreux et avant la mise en bouteille de vins finis. De plus, les analyses chimiques et sensorielles menées sur les vins traités ne montrent aucun impact sur la qualité des vins. Le chauffage ohmique est ici utilisé comme procédé de stabilisation thermique des mouts et des vins. Lors du passage d’un courant à travers un matériau ayant une résistance électrique, l’énergie électrique est transformée en énergie thermique. La chaleur est alors générée à l’intérieur même de la matière à traiter. Les résultats des travaux ont montré pour la première fois que la rapidité et l’homogénéité de chauffe permettent une stabilisation efficace des vins et des mouts sans préjudices sur leur qualité.

In this article, we investigate Gevrey and summability properties of the formal power series solutions of the inhomogeneous generalized Boussinesq equations. Even if the case that really matters physically is an analytic inhomogeneity, we systematically examine here the cases where the inhomogeneity is s-Gevrey for any s ⩾ 0, in order to carefully distinguish the influence of the data (and their degree of regularity) from that of the equation (and its structure). We thus prove that we have a noteworthy dichotomy: for any s ⩾ 1, the formal solutions and the inhomogeneity are simultaneously s-Gevrey; for any s < 1, the formal solutions are generically 1-Gevrey. In the latter case, we give in particular an explicit example in which the formal solution is s ′ -Gevrey for no s ′ < 1, that is exactly 1-Gevrey. Then, we give a necessary and sufficient condition under which the formal solutions are 1-summable in a given direction arg ( t ) = θ. In addition, we present some technical results on the generalized binomial and multinomial coefficients, which are needed for the proofs of our various results.

23 pages; International audience; In this paper, we study sheets of symmetric Lie algebras through their Slodowy slices. In particular, we introduce a notion of slice induction of nilpotent orbits which coincides with the parabolic induction in the Lie algebra case. We also study in more details the sheets of the non-trivial symmetric Lie algebra of type G2. We characterize their singular loci and provide a nice desingularization lying in so7.In this new version, computations of section 4 are pared down. Important modifications of the exposition of Section 3 on slice induction.

International audience; Today’s artificial intelligence, largely based on data-intensive machine learning algorithms, relies heavily on the digital labour of invisibilized and precarized humans-in-the-loop who perform multiple functions of data preparation, verification of results, and even impersonation when algorithms fail. Using original quantitative and qualitative data, the present article shows that these workers are highly educated, engage significant (sometimes advanced) skills in their activity, and earnestly learn alongside machines. However, the loop is one in which human workers are at a disadvantage as they experience systematic misrecognition of the value of their competencies and of their contributions to technology, the economy, and ultimately society. This situation hinders negotiations with companies, shifts power away from workers, and challenges the traditional balancing role of the salary institution.

International audience

International audience; In this paper, we propose an instantiation, called \textsf{Stanislas}, of a dedicated Self-Synchronizing Stream Cipher (SSSC) involving an automaton with finite input memory using non-triangular state transition functions. Previous existing SSSC are based on automata with shifts or triangular functions (T-functions) as state transition functions. Our algorithm Stanislas admits a matrix representation deduced from a general and systematic methodology called Linear Parameter Varying (LPV). This particular representation comes from the automatic theory and from a special property of dynamical systems called flatness.

International audience; In the context of climate change, assessing how likely a particular change or event has been caused by human influence is important for mitigation and adaptation policies. In this work we propose an extreme event attribution (EEA) methodology to analyze yearly maxima records, key indicators of climate change that spark media attention and research in the EEA community. Although they deserve a specific statistical treatment, algorithms tailored to record analysis are lacking. This is particularly true in a non-stationarity context. This work aims at filling this methodological gap by focusing on records in transient climate simulations. We apply our methodology to study records of yearly maxima of daily precipitation issued from numerical climate model IPSL-CM6A-LR. Illustrating our approach with decadal records, we detect in 2023 a clear human induced signal in half of the globe, with probability mostly increasing, but decreasing in the south and north Atlantic oceans

A large number of behavioral studies suggest that confidence judgments are impaired in schizophrenia, motivating the search for neural correlates of an underlying metacognitive impairment. Electrophysiological studies suggest that a specific evoked response potential reflecting performance monitoring, namely the error-related negativity (ERN), is blunted in schizophrenia compared to healthy controls. However, attention has recently been drawn to a potential confound in the study of metacognition, namely that lower task-performance in schizophrenia compared to healthy controls involves a decreased index of metacognitive performance (where metacognitive performance is construed as the ability to calibrate one’s confidence relative to response correctness), independently of metacognitive abilities among patients. Here, we assessed how this confound might also apply to ERN-blunting in schizophrenia. We used an adaptive staircase procedure to titrate task-performance on a motion discrimination task in which participants (N = 14 patients and 19 controls) had to report their confidence after each trial while we recorded high density EEG. Interestingly, not only metaperceptual abilities were preserved among patients at the behavioral level, but contrary to our hypothesis, we also found no electrophysiological evidence for altered EEG markers of performance monitoring. These results bring additional evidence suggesting an unaltered ability to monitor perceptual performance on a trial by trial basis in schizophrenia.

Scientific research is growingly increasingly reliant on "microwork" or "crowdsourcing" provided by digital platforms to collect new data. Digital platforms connect clients and workers, charging a fee for an algorithmically managed workflow based on Terms of Service agreements. Although these platforms offer a way to make a living or complement other sources of income, microworkers lack fundamental labor rights and basic safe working conditions, especially in the Global South. We ask how researchers and research institutions address the ethical issues involved in considering microworkers as "human participants." We argue that current scientific research fails to treat microworkers in the same way as in-person human participants, producing de facto a double morality: one applied to people with rights acknowledged by states and international bodies (e.g., the Helsinki Declaration), the other to guest workers of digital autocracies who have almost no rights at all. We illustrate our argument by drawing on 57 interviews conducted with microworkers in Spanish-speaking countries.

La présente contribution analyse le processus de mise en récit de l'expérience carcérale par les détenues, en fonction du dispositif du parcours d'exécution de peine. Comment construire un récit au plus près de soi dans un procédé disciplinaire à la recherche d'une unicité de parcours aux normes assujettissantes ? Quand produire une parole sur soi pour se libérer du processus carcéral, alors que celle-ci est conditionnée à l'intérieur d'un système de répression ? Quelles sont les possibilités du discours sur soi dans l'enfermement et le parcours d'évaluation de la peine ? En interrogeant les catégories de discours et de jugement sur lesquelles se fonde le couple auteure/victime, je procéderai à l'examen de ces catégories selon le contexte d'interaction et d'énonciation. Ce cadre analytique permettra de faire appara\ⁱtre le rapport souvent dysfonctionnel entre l'usage juridique de ces notions et leur inscription dans le réel des femmes incarcérées pour de moyennes et longues peines, façonné dans des logiques de domination des rapports sociaux de genre et de classe sociale.

International audience; In this work we deal with the exponential stability of the nonlinear Kortewegde Vries (KdV) equation on a finite star-shaped network in the presence of delayed internal feedback. We start by proving the well-posedness of the system and some regularity results. Then we state an exponential stabilization result using a Lyapunov function by imposing small initial data and a restriction over the lengths. In this part also, we are able to obtain an explicit expression for the rate of decay. Then we prove the exponential stability of the solutions without restriction on the lengths and for small initial data, this result is based on an observability inequality. After that, we obtain a semi-global stabilization result working directly with the nonlinear system. Next we study the case where it may happen that a control domain with delay is outside of the control domain without delay. In that case, we obtain also a local exponential stabilization result. Finally, we present some numerical simulations in order to illustrate the stabilization.

Given F a locally compact, non-discrete, non-archimedean field of characteristic different from 2 and R an integral domain such that a non-trivial smooth F-character with values in the multiplicative group of R exists, we construct the (reduced) metaplectic group attached to R. We show that it is in most cases a double cover of the symplectic group over F. Finally we define a faithful infinite dimensional R-representation of the metaplectic group analogue to the Weil representation in the complex case.

In this Paper we are interested in the geometric local theta correspondence at the Iwahori level especially for dual reductive pairs of type II over a non Archimedean field F of characteristic p different from 2 as well as the geometric Arthur- Langlands functoriality at the Iwahori level. We consider the geometric version of the invariants of the Weil representation of the Iwahori-Hecke algebras. We give a complete geometric description of the corresponding category for (GL1, GLm). Additionally given two reductive connected groups G, H over F and a morphism \check{G}\times SL2 \to \check{H} of Langlands dual groups, we suggest a bimodule over the a ffine extended Hecke algebras of H and G that should realize the local geometric Arthur- Langlands functoriality at the Iwahori level. We propose a conjecture describing the geometric Howe correspondence in terms of this bimodule and prove our conjecture for the pair (GL1, GLm) for any m.

In a previous article [1], an implementation of lazy p-adic integers with a multiplication of quasi-linear complexity, the so-called relaxed product, was presented. Given a ring R and an element p in R, we design a relaxed Hensel lifting for algebraic systems from R/ (p) to the p-adic completion Rp of R. Thus, any root of linear and algebraic regular systems can be lifted with a quasi-optimal complexity. We report our implementations in C++ within the computer algebra system Mathemagix and compare them with Newton operator. As an application, we solve linear systems over the integers and compare the running times with Linbox and IML.

In geometric terms, given a singular foliation of the plane, a dicritical divisor is (whenever it exists) an irreducible component of the exceptional divisor which is transverse to the foliation. Abhyankar gave recently a definition of the dicritical divisors which generalize and algebraicize the geometrical definition in the local case and the polynomial case. Following his work, we give a geometrical interpretation of these dicritical divisors and new proofs of their existence., Comment: 9 pages, in French

Version préliminaire (04/05/2011) d'un travail publié sous forme définitive (15/09/2011); International audience; In [AL11], S.S Abhyankar and I. Luengo introduce a new theory of dicritical divisors in the most general framework. Here we simplify and generalize their results (see Theorems 3.1 and 3.2).

Let $F/F_{\mathsf{o}}$ be a quadratic extension of non-archimedean locally compact fields of odd residual characteristic and $\sigma$ be its non-trivial automorphism. We show that any $\sigma$-self-dual cuspidal representation of ${\rm GL}_n(F)$ contains a $\sigma$-self-dual Bushnell--Kutzko type. Using such a type, we construct an explicit test vector for Flicker's local Asai $L$-function of a ${\rm GL}_n(F_{\mathsf{o}})$-distinguished cuspidal representation and compute the associated Asai root number. Finally, by using global methods, we compare this root number to Langlands--Shahidi's local Asai root number, and more generally we compare the corresponding epsilon factors for any cuspidal representation., Comment: 61 pages, final version to appear in JEMS

International audience; In this paper, we consider the numerical approximation of hyperbolic systems of conservation laws with sti source terms and parabolic degeneracy in the asymptotic limit. We are more precisely interested in the design of high-order asymptotic-preserving schemes on unstructured meshes. Our approach is based on a very simple modication of the numerical ux associated with the usual HLL scheme and boils down to a sharp control of the underlying numerical diusion. The strategy allows to capture the correct asymptotic parabolic behavior and to preserve the high-order accuracy also in the asymptotic limit. Numerical experiments are proposed to illustrate these properties.

In this note we present Hironaka's invariants as developed by Giraud: the ridge and the directrix. We give an effective definition and a functorial one and show their equivalence. The fruit is an effective algorithm that computes the additive generators of the "ridge", and the generators of its invariant algebra.

Submitted; We are interested in the Gevrey properties of the formal power series solution in time of the inhomogeneous semilinear heat equation with a power-law nonlinearity in $1$-dimensional time variable $t\in\mathbb{C}$ and $n$-dimensional spatial variable $x\in\mathbb{C}^n$ and with analytic initial condition and analytic coefficients at the origin $x=0$. We prove in particular that the inhomogeneity of the equation and the formal solution are together $s$-Gevrey for any $s\geq1$. In the opposite case $s

International audience

International audience; When dealing with full spectrum images in which each pixel is characterized by a full spectrum, ie. spectral images, standard segmentation methods, such as k-means or hierarchical clustering might be either inapplicable or inappropriate ; one aspect being the multi-GB size of such data set leading to very expensive computations. In the present contribution, we propose an approach to spectral image segmentation combining hierarchical clustering and spatial constraints. On the one hand spatial constraints allow to implement an algorithm with a reasonable computation time to obtain a segmentation and with a certain level of robustness with respect to the signal-to-noise ratio since the prior knowledge injected by the spatial constraint partially compensates for the increase in noise level. On the other hand hierarchical clustering provides a statistically sound and known framework that allows accurate reporting of the instrument noise model. In terms of applications, this segmentation problem is encountered particularly in the study of ancient materials that benefits from the wealth of information provided by the acquisition of spectral images. In the last few years, data collection has been considerably accelerated, enabling the characeterization of the sample with a high dynamic range in both the spatial dimensions and composition and leading to an average size of a single data set in the tens of GB range. Hence we also considered computational and memory complexity when developing the herein proposed algorithm. Taking on this application domain, we illustrate the proposed algorithm on a X-ray fluorescence spectral image collected on an ca. 100 Myr fossil fish, as well as on simulated data to assess the sensitivity of the results to the noise level. For such experiment, the lower sensitivity to noise simultaneously lead to an increase in the spatial definition of the collected spectral image, thanks to the faster acquisition time, and to a reduction in the potentially harmful radiation dose density to which the samples are subjected.

A new modality of Compton scattering tomography (CST) is presented. This model is composed of a fixed source and detectors placed on a fixed ring passing through the source. This new modality, called circular CST (CCST), allows to register a complete set of data and, regarding constructive features like compactness or the absence of moving components, outperforms other existing CST designs. A bi-imaging system combining this new system and fan-beam computed tomography can also be considered, and such system will provide both the attenuation map and the distribution on electrons of the object under study. The modeling of the CCST leads to the Radon transform (RT) on circles passing through a fixed point. A reconstruction algorithm based on an exact inversion formula of the RT on circles is proposed and numerical simulations for image formation and reconstruction are carried out. The results show the viability of this new image system which is particularly suitable for small objects, such as biomedical objects.

We are interested in the numerical approximation of discontinuous solutions in non conservative hyperbolic systems. We introduce the basics of a new strategy based on in-cell discontinuous reconstructions to deal with this challenging topic, and apply it to a 2x2 non conservative toy model, and a 3x3 gas dynamics system in Lagrangian coordinates. The strategy allows in particular to compute exactly isolated shocks. Numerical evidences are proposed.

This paper presents the Subterranean 2.0 cipher suite that can be used for hashing, MAC computation, stream encryption and several types of authenticated encryption schemes. At its core it has a duplex object with a 257-bit state and a lightweight single-round permutation. This makes Subterranean 2.0 very well suited for low-area and low-energy implementations in dedicated hardware., IACR Transactions on Symmetric Cryptology, Volume 2020, Special Issue 1

Cryptographic competitions, like the ongoing NIST call for lightweight cryptography, always provide a thriving research environment, where new interesting ideas are proposed and new cryptographic insights are made. One proposal for this NIST call that is accepted for the second round is Pyjamask. Pyjamask is an authenticated encryption scheme that builds upon two block ciphers, Pyjamask-96 and Pyjamask-128, that aim to minimize the number of AND operations at the cost of a very strong linear layer. A side-effect of this goal is a slow growth in the algebraic degree. In this paper, we focus on the block cipher Pyjamask-96 and are able to provide a theoretical key-recovery attack reaching 14 (out of 14) rounds as well as a practical attack on 8 rounds. We do this by combining higher-order differentials with an in-depth analysis of the system of equations gotten for 2.5 rounds of Pyjamask-96. The AEAD-scheme Pyjamask itself is not threatened by the work in this paper., IACR Transactions on Symmetric Cryptology, Volume 2020, Issue 1

We consider regular variation for marked point processes with independent heavy-tailed marks and prove a single large point heuristic: the limit measure is concentrated on the cone of point measures with one single point. We then investigate successive hidden regular variation removing the cone of point measures with at most k points, k ≥ 1, and prove a multiple large point phenomenon: the limit measure is concentrated on the cone of point measures with k + 1 points. We show how these results imply hidden regular variation in Sko-rokhod space of the associated risk process, in connection with the single/multiple large point heuristic from Rhee et al. (2019). Finally, we provide an application to risk theory in a reinsurance model where the k largest claims are covered and we study the asymptotic behavior of the residual risk.

International audience; Throughout 2020, essays and interviews by researchers from social sciences and humanities were published in the press. Many of them reflected on a « post-pandemic world ». A corpus consisting of 1550 articles from the French national press and newsblog entries was collected at the MSH-ParisSaclay/CNRS and analysed using a thematic review of items imagining a « world after the pandemic ». This article highlights visions of happiness in the future, in foreign and distant countries and analyses their underlying ideas of crisis. Indeed, happiness ought to be understood as a – currently unattainable - metaphor to differentiate between the pandemic as a state of uncertainty and redefinitions of the future spurred by the pandemic itself. Past, present and future are linked via a utopic – sometimes dystopic – vision of the future, where the pandemic acts as an accelerator of the ongoing paradigms, in particular in regard to the developing world. These articles use eurocentristic strategies of othering and orientalism to construct futures scenarios of international relations.

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Cette enquête, proposée par l’ensemble du réseau des bibliothèques et centres de documentation et le Comité de pilotage de la Science Ouverte de l’Université Paris-Saclay en 2021, s’inscrit dans un contexte dynamique de Science Ouverte prônant l’obligation de publication des données de la recherche selon les principes FAIR (Facilement trouvable, Accessible, Interopérable, Réutilisable).L'ambition de cette enquête est de dresser un paysage le plus complet et élargi possible autour des pratiques de la recherche. Elle s’adressait à tous les chercheur·es, ingénieur·es de recherche et d’études, doctorant·es ou encore personnels administratifs de l’ensemble de l’université, en somme toutes personnes amenées à créer, manipuler, utiliser des données, et ce dans tous les établissements de l’Université.L’enquête répond à un triple objectif : - Établir un panorama des données produites au sein de l’Université- Dresser le paysage des pratiques autour des données de la recherche- Connaître les besoins des chercheur·es autour des donnéespour adapter et améliorer l'offre de services.

International audience; Around the world, myriad workers perform micro-tasks on online platforms to train and calibrate artificial intelligence solutions. Despite its apparent openness to anyone with basic skills, this form of crowd-work fails to fill gender gaps, and may even exacerbate them. We demonstrate this result in three steps. First, inequalities in both the professional and domestic spheres turn micro-tasking into a ‘third shift’ that adds to already heavy schedules. Second, the human and social capital of male and female workers differ– leaving women with fewer career prospects within a tech-driven workforce. Third, female micro-work reproduces relegation of women to lower-level computing work observed in the history of science and technology.

International audience; This article was based upon an ethnographic study undertaken in 2017 and 2018 in a women's prison in France. It relies on 42 interviews with inmates and 36 public and private employees and professionals that were carried out in a variety of carceral spaces (cell, exercise rooms, workshops, spaces for cultural, pedagogical or sports activities, professional training, collective gatherings in the courtyard or specially designated ``socializing''\textendash or leisure \textendash rooms). While carceral social life is always shaped by confinement and the never-ending confrontation between different logics of otherness around gender and race, this article focuses on the conditions for same-sex sexual and emotional lives among women. How do these relationships unfold and what might be the disciplinary modes of control that lesbians are subjected to while incarcerated? How, for what use, and to what effect are categories of gender and race mobilized within this heteronormative space?

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In this article we exploite the uniform decay for damped linear wave equation with Zaremba boundary condition, obtained in a previous work, to treat the same problem in nonlinear context. We need a uniqueness assumption, usual for this type of nonlinear problem. The result is deduced from an observation estimate for nonlinear problem proved by a contradiction argument., arXiv admin note: substantial text overlap with arXiv:1909.10044

International audience; This paper presents the first publicly available cryptanalytic attacks on the GEA-1 and GEA-2 algorithms. Instead of providing full 64-bit security, we show that the initial state of GEA-1 can be recovered from as little as 65 bits of known keystream (with at least 24 bits coming from one frame) in time $2^{40}$ GEA-1 evaluations and using 44.5 GiB of memory. The attack on GEA-1 is based on an exceptional interaction of the deployed LFSRs and the key initialization, which is highly unlikely to occur by chance. This unusual pattern indicates that the weakness is intentionally hidden to limit the security level to 40 bit by design. In contrast, for GEA-2 we did not discover the same intentional weakness. However, using a combination of algebraic techniques and list merging algorithms we are still able to break GEA-2 in time $2^{45.1}$ GEA-2 evaluations. The main practical hurdle is the required knowledge of 1600 bytes of keystream.

In this article we prove, under some geometrical condition on geodesic flow, exponential stabilization of wave equation with Zaremba boundary condition. We prove an estimate on the resolvent of semigroup associated with wave equation on the imaginary axis and we deduce the stabilization result. To prove this estimate we apply semiclassical measure technics. The main difficulties are to prove that support of measure is in characteristic set in a neighborhood of the jump in the boundary condition and to prove results of propagation in a neighborhood of a boundary point where Neumann boundary condition is imposed. In fact if a lot of results applied here are proved in previous articles, these two points are new.

International audience

International audience; Les changements importants imposés par l’urgence climatique, la numérisation accélérée des activités économiques et la crise sanitaire interrogent la manière dont on comprend le monde et ses évolutions. À ce titre, l’énergie demeure au centre des débats sur l’avenir des sociétés. Les défis actuels de la transition énergétique – qui consiste à abandonner les combustibles fossiles (pétrole, gaz naturel et charbon) au profit d’un nouveau modèle énergétique – reposent à la fois sur la maîtrise de la consommation d’énergie et sur le déploiement à grande échelle de sources renouvelables (comme le soleil, le vent, l’eau en mouvement, les réactions chimiques des matières organiques vivantes…). L’ouvrage propose une approche originale qui croise les regards de chimistes, économistes et juristes sur la transition énergétique actuelle. Il réunit des contributions présentées dans le cadre du workshop MOMENTOM (MOlecules and Materials for the ENergy of TOMorrow) organisé le 21 novembre 2019 à la Maison des Sciences de l’Homme Paris-Saclay. En particulier, la transition énergétique est analysée sous l’angle du droit, par référence à la protection des libertés individuelles et à la garantie de l’accès à une énergie bon marché. Cette transition énergétique est également traitée à travers certaines innovations technologiques telles que l’hydrogène et les batteries à des fins de stockage de l’énergie. On trouvera notamment une analyse économique de l’évolution de la demande mondiale d’hydrogène à l’horizon 2050, ainsi que de l’usage de ce matériau dans le secteur des bus urbains. Au niveau international, les scientifiques et notamment les chimistes consacrent beaucoup d’efforts à imiter le monde du vivant pour produire une énergie propre. Les énormes défis consistent à développer des matériaux avancés, abondants, peu coûteux et éco-compatibles. À titre d’illustration, l’ouvrage traite des dernières avancées scientifiques réalisées visant à produire du carburant solaire par de la photosynthèse artificielle. Il analyse enfin les enjeux de la transition énergétique en termes de comportements de consommation. À ce titre, l’installation de dispositifs de comptage intelligent de la consommation électrique (type Linky) par les gestionnaires des réseaux de distribution électrique au domicile des usagers peut conduire à des conflits, les consommateurs ne faisant pas toujours confiance aux entreprises énergétiques pour agir dans leur meilleur intérêt et se méfiant de l’utilisation abusive de leurs données de consommation. La solution à ces conflits est de plus en plus souvent confiée à la justice. Les apports scientifiques pluridisciplinaires éclairent plusieurs questions, dont notamment celles-ci : comment pareille transition rencontre-t-elle le droit par référence à la protection des libertés individuelles et à la garantie de la sécurité de chacun ? Sous quelles conditions les innovations technologiques, telles que la solution hydrogène pour la mobilité et la batterie pour le stockage de l’énergie électrique, peuvent-elles être déployées à grande échelle ? Quels sont les obstacles à l’appropriation par les usagers des technologies contribuant à la maîtrise de leur consommation d’énergie ?

In this thesis, we consider several concrete examples of the relation among the local Langlands correspondence, its functoriality and the problem of distinction. Let F/F_0 be a finite cyclic extension of non-archimedean locally compact fields of residue characteristic p and let R be an algebraically closed field of characteristic l different from p. In the first part, we assume F/F_0 to be quadratic and p to be odd, and we study the irreducible representations of GL_n(F) over R distinguished by a unitary subgroup. We completely solve the problem for supercuspidal representations and get partial results for generic representations. Meanwhile we also define an l-modular version of the cyclic base change lift. In the second part, we assume F=F_0 and p odd, and we fully characterize the complex supercuspidal representations of GL_n(F) distinguished by an orthogonal subgroup. In the final part for F/F_0 tamely ramified, we study the base change lift and the automorphic induction for complex supercuspidal representations via the simple type theory.; Dans cette thèse, nous considérons quelques exemples concrets de la relation entre la correspondance de Langlands locale, sa fonctorialité et le problème de la distinction. Soit F/F_0 une extension cyclique finie de corps localement compacts non-archimédiens de caractéristique résiduelle p et soit R un corps algébriquement clos de caractéristique l différent à p. Dans la première partie, nous supposons que F/F_0 est quadratique et p est impair, et nous étudions les représentations irréductibles de GL_n(F) sur R distinguées par un sous-groupe unitaire. Nous résolvons complètement le problème pour les représentations supercuspidales et obtenons des résultats partiels pour les représentations génériques. Nous définissons également une version l-modulaire du changement de base cyclique. Dans la deuxième partie, nous supposons que F=F_0 et p est impair, et nous caractérisons complètement les représentations supercuspidales complexes de GL_n(F) distinguées par un sous-groupe orthogonal. Dans la dernière partie pour F/F_0 modérément ramifiée, nous étudions le changement de base et l'induction automorphe pour des représentations supercuspidales complexes via la théorie des types simples.

International audience; Additive polynomials play an important role in the local study of singularities in positive characteristic. For a base field k, the Hilbert-Samuel stratum of an affine cone over k is a linear space if k is perfect, but this is no longer true in general over non-perfect fields. H. Hironaka introduced additive subgroups in 1970 in order to quantify this phenomenon but little is known about classifying them except in small dimension.Building on joint works with A. Benito and A. Reguera on arc spaces, and with V. Cossart and B. Schober on the Hilbert-Samuel stratum, I will point out some of the questions arising for hypersurface cones defined by an additive polynomial of degree p in characteristic p>0.

Let G be a semisimple algebraic group of adjoint type, let H be a subgroup of G, that is fixed under an involution. The symmetric space G/H possesses a wonderful compactification by De Concini and Procesi.We study the moduli space of rational curves with no marked points of wonderful symmetric varieties and we prove that the said moduli space is reducible for many cases. After that we consider a special case of wonderful symmetric varieties - wonderful group compactification. For wonderful group compactifications the component of the moduli space of rational curves, that are irreducible and meet the open GxG-orbi of the wonderful group compactification of G is itself irreducible.; Nous fournissons d'abord un contexte général sur les variétés magnifiques et les espaces de modules des courbes rationnelles. En travaillant sur les nombres complexes, nous prouvons que l'espace de modules des courbes rationnelles sans points marqués sur la compactification merveilleuse d'un espace symétrique n'est pas irréductible en général.Enfin, nous montrons que dans le cas des compactifications magnifiques de groupes, l'ensemble des courbes rationnelles sans points marqués et de source irréductible est irréductible.

The present work is devoted to the numerical approximation of the Shallow water Exner system in both one and two dimensions, where the Exner equation expresses the evolution in time of the bed sediment. In particular the Grass formula is taken into account to model the solid transport discharge contributions. The numerical scheme is based on the Lagrange-projection formalism which consists in splitting the mathematical model into the acoustic and transport system. In particular, the Exner equation is taken into account only at the transport level; both a decoupled and weakly coupled formulation are proposed. The method is designed in such a way to satisfy the well-balanced property as well. Details to reach the second-order of accuracy are given; numerical results are shown to validate the numerical schemes.

International audience; We investigate the dynamics of inverted pendulum structures under fast-dynamic excitations arising from an explosion. We model blast actions using established empirical models and best-fit interpolations of existing experimental tests. We focus attention on pure rocking response mechanisms. We present moment balance equations and overturning conditions. Inspired by previous works in the frame of earthquake engineering, we derive new analytical, closed-form solutions for the rocking response and the overturning domain of slender blocks due to explosions.The analytical findings and assumptions are validated through existing experimental tests and detailed three-dimensional numerical simulations, which consider the full interaction between the blast waves and the structure. We show that unilateral rocking response and overturning are predominant mechanisms compared to sliding and up-lifting.Finally, we develop design charts to be used as a straightforward decision making tool for determining the critical stand-off distance between the explosive source and the target in order to prevent overturning. Our model can be easily applied for the design of protective devices to preserve artefacts, secure buildings and humans, as well as for devising energy absorbing systems based on rocking.

International audience; We provide quantitative estimates in total variation distance for positive semi-groups, which can be non-conservative and non-homogeneous. The techniques relies on a family of conservative semigroups that describes a typical particle and Doeblin's type conditions for coupling the associated process. Our aim is to provide quantitative estimates for linear partial differential equations and we develop several applications for population dynamics in varying environment. We start with the asymptotic profile for a growth diffusion model with time and space non-homogeneity. Moreover we provide general estimates for semigroups which become asymptotically homogeneous, which are applied to an age-structured population model. Finally, we obtain a speed of convergence for periodic semi-groups and new bounds in the homogeneous setting. They are are illustrated on the renewal equation.

Let $\mathbb{F}$ be a field and $f : \mathfrak{S}_n \rightarrow \mathbb{F} \setminus \{0\}$ be an arbitrary map. The Schur matrix functional associated to $f$ is defined as $M \in \text{M}_n(\mathbb{F}) \mapsto \widetilde{f}(M):=\sum_{\sigma \in \mathfrak{S}_n} f(\sigma) \prod_{j=1}^n m_{\sigma(j),j}$. Typical examples of such functionals are the determinant (where $f$ is the signature morphism) and the permanent (where $f$ is constant with value $1$). Given two such maps $f$ and $g$, we study the endomorphisms $U$ of the vector space $\text{M}_n(\mathbb{F})$ that satisfy $\widetilde{g}(U(M))=\widetilde{f}(M)$ for all $M \in \text{M}_n(\mathbb{F})$. In particular, we give a closed form for the linear preservers of the functional $\widetilde{f}$ when $f$ is central, and as a special case we extend to an arbitrary field Botta's characterization of the linear preservers of the permanent., Comment: 60 pages

In this article we propose an automatic selection of the bandwidth of the recursive kernel density estimators for spatial data defined by the stochastic approximation algorithm. We showed that, usi...

In this paper we propose a numerical method to approximate the best decay rate for some dissipative systems that are bounded perturbation of unbounded skew-adjoint operators. We also give some numerical examples and applications to illustrate the efficiency of this approach.

In this text, we investigate webs which can be associated to cluster algebras from the point of view of the abelian functional equations these webs carry, focusing on the polylogarithmic ones. We introduce a general notion of webs whose rank is `As Maximal as Possible' (AMP) and show that many webs associated either to polylogarithmic functional equations or to cluster algebras are of this type. In particular, we prove a few results and state some conjectures about cluster webs associated to (pairs of) Dynkin diagrams. Along the way, we show that many of the classical functional equations satisfied by low-order polylogarithms (such as Spence-Kummer's equation of the trilogarithm or the tetralogarithmic one of Kummer) are of cluster type., 298 pages, many figures. Preliminary version. Comments are welcome

Variable Length Memory Chains (VLMC), which are generalizations of finite order Markov chains, turn out to be an essential tool to modelize random sequences in many domains, as well as an interesting object in contemporary probability theory. The question of the existence of stationary probability measures leads us to introduce a key combinatorial structure for words produced by a VLMC: the Longest Internal Suffix. This notion allows us to state a necessary and sufficient condition for a general VLMC to admit a unique invariant probability measure. This condition turns out to get a much simpler form for a subclass of VLMC: the stable VLMC. This natural subclass, unlike the general case, enjoys a renewal property. Namely, a stable VLMC induces a semi-Markov chain on an at most countable state space. Unfortunately, this discrete time renewal process does not contain the whole information of the VLMC, preventing the study of a stable VLMC to be reduced to the study of its induced semi-Markov chain. For a subclass of stable VLMC, the convergence in distribution of a VLMC towards its stationary probability measure is established. Finally, finite state space semi-Markov chains turn out to be very special stable VLMC, shedding some new light on their limit distributions., Comment: arXiv admin note: text overlap with arXiv:1807.01075

International audience; La manière dont le changement des pratiques et des modes de vie contribue à la transition écologique, économique et sociale est un enjeu majeur pour les pouvoirs publics, à tous les échelons de gouvernement. Pour parvenir à amorcer cette transition, les politiques publiques visent à faire prendre conscience aux citoyen·ne·s de l’impact de leurs pratiques sur l’environnement, tout en veillant à ce que leur mise en œuvre ne paraisse pas décorrélée du quotidien, ni ne soit perçue comme entraînant contraintes ou exclusion sociale.S’inscrivant dans le cadre du projet Construire des mobilités durables, inclusives et responsables (CONDUIRE), financé par l’Agence de l’Environnement et de la Maîtrise de l’Énergie (ADEME), les actes du colloque « Peut-on se passer de la voiture hors des centres urbains ? » cherchent à analyser le problème de la dépendance automobile en zones peu denses – il s’agit notamment des espaces ruraux ou situés en périphérie des grandes villes –, ainsi que les différentes solutions à y apporter. Portant attention à l’objectif de préserver, lors de la conversion écologique des mobilités, leur capacité à inclure – on parle d’« inclusivité sociale » –, cet ouvrage s’attache également à interroger les pratiques de déplacements de ménages populaires résidant dans ces territoires. Il a ainsi pour ambition d’identifier les ressorts de la transition vers des mobilités plus durables, et aussi plus inclusives, au sein des espaces où l’automobile reste prégnante.Son fil rouge est le paradoxe selon lequel les solutions de substitution à la voiture sont proposées et mises en place quasi exclusivement dans les zones denses – il s’agit notamment des grandes villes –, pourtant les moins dépendants à l’automobile. Les espaces périphériques, pour autant caractérisés par un usage intensif et croissant de la voiture, lui connaissent en effet peu d’alternatives écologiques et inclusives. Aussi, le développement de la transition économique, écologique et sociale ne peut faire l’économie d’une étude approfondie des usages de la voiture dans de tels espaces qui, d’une part, contribuent certes d’une façon importante à la pollution atmosphérique mais qui, d’autre part, concentrent les populations pour lesquelles la voiture est à la fois indispensable, contraignante et coûteuse, comme le mouvement social des Gilets jaunes en 2018-2019 l’a laissé entrevoir.L’objectif de l’ouvrage est donc d’interroger la dépendance automobile à plusieurs échelles temporelles et spatiales, tout en proposant une analyse des alternatives à la voiture, y compris au sein des zones de peuplement les moins denses. À partir de divers exemples situés en France, mais aussi au Canada, la première partie de l’ouvrage offre un panorama historique et spatial de la dépendance à l’automobile, amenant des réflexions sur le futur de la voiture dans ces espaces. Dans un deuxième temps, l’ouvrage questionne les représentations et les usages contemporains de l’automobile hors des villes, au travers d’enquêtes auprès des populations belge, camerounaise et française. La troisième et dernière partie s’attache enfin à comprendre les conditions de possibilité (et d’impossibilité) des formes de mobilité alternative à la voiture au sein des divers territoires : covoiturages, motorisation électrique (notamment d’occasion) et tiers-lieux (espaces de coworking).