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Chronologie de l’adaptation des karsts et des versants à la dynamique d’incision quaternaire dans le Bassin parisien : présentation de l'avancement des travaux
No full textInternational audienc
Unconditionally stable time discretization of Lindblad master equations in infinite dimension using quantum channels
No full textWe examine the time discretization of Lindblad master equations in infinite-dimensional Hilbert spaces. Our study is motivated by the fact that, with unbounded Lindbladian, projecting the evolution onto a finite-dimensional subspace using a Galerkin approximation inherently introduces stiffness, leading to a Courant--Friedrichs--Lewy type condition for explicit integration schemes. We propose and establish the convergence of a family of explicit numerical schemes for time discretization adapted to infinite dimension. These schemes correspond to quantum channels and thus preserve the physical properties of quantum evolutions on the set of density operators: linearity, complete positivity and trace. Numerical experiments inspired by bosonic quantum codes illustrate the practical interest of this approach when approximating the solution of infinite dimensional problems by that of finite dimensional problems of increasing dimension
Performance of multiple filter-cavity schemes for frequency-dependent squeezing in gravitational-wave detectors
No full textInternational audienceGravitational-wave detectors use state-of-the-art quantum technologies to circumvent vacuum fluctuations via squeezed states of light. Future detectors such as Einstein Telescope may require the use of two filter cavities or a 3-mirror, coupled filter cavity to achieve a complex rotation of the squeezing ellipse in order to reduce the quantum noise over the whole detector bandwidth. In this work, we compare the theoretical feasibility and performances of these two systems and their resilience with respect to different degradation sources (optical losses, mismatching, locking precision). We provide both analytical models and numerical insights. We extend previous analysis on squeezing degradation and find that the coupled cavity scheme provides similar or better performances than the two-cavity option, in terms of resilience with respect to imperfections and optical losses. We propose a possible two-step implementation scheme for Einstein Telescope using a single filter cavity that can be possibly upgraded into a coupled filter cavity
Deep Learning and Spatial Context for Global Horizontal Irradiance Estimation: Addressing Independent Pixel Approximation Limitations with Satellite Imagery
No full textInternational audienceAccurate estimation of Global Horizontal Irradiance (GHI) is essential for solar energy applications, climate modeling, and various geophysical processes.Traditional satellite-based methods rely on the Independent Pixel Approximation (IPA), which treats each pixel as radiatively isolated from its neighbors, neglecting 3D cloud effects and horizontal photon transport. These limitations could be amplified by the higher spatial, temporal, and spectral resolutions of third-generation geostationary satellites. In this study, we evaluate deep learning models that explicitly incorporate spatial context from GOES-16 multispectral satellite imagery to improve satellite-based GHI estimation and address IPA limitations.We compare two architectures—a Fully Connected Network (FCN) and a convolutional-based model—against a state-of-the-art physical retrieval method (PSM3), using in-situ GHI measurements from 31 U.S. stations.Our results show that deep learning models leveraging spatial context outperform PSM3 across most metrics, especially under cloudy and partially clear conditions, yielding improved performance, stability, and reduced bias. The best-performing model achieves a 26.5% lower RMSE and a 21% lower MAE compared to PSM3 on a year-long test set. However, deep learning models still struggle to consistently outperform PSM3 in some scenarios in terms of bias, particularly under clear-sky conditions or on some specific test stations.Qualitative analysis highlights specific weakness modes of PSM3, particularly when it misclassifies cloudy scenes as clear-sky, where deep learning models correctly capture cloud-induced variability.We discuss the implications of these findings and potential directions for model improvements. This work underscores the potential of spatial-context-aware deep learning models to overcome IPA limitations for the next generation of satellite-based GHI retrieval methods, and improve GHI retrieval in heterogeneous atmospheric conditions
What makes minerals critical? Problematizing sovereignty in times of crisis
No full textInternational audienceThis paper examines what makes minerals "critical" by analyzing criticality studies, which are geological and economic analyses aimed at forecasting future supply risks. It explores three contemporary examples from European and French contexts. In Europe, critical materials are discussed in relation to the recent Critical Raw Materials Act. While the European approach highlights a crisis in Europe’s capacity to monitor and respond to market trends, the French cases present different ways of framing the crisis. One case, involving the institution Ofremi, focuses on outlining strategic directions to safeguard national sovereignty and prepare for external threats to the economy. The other stems from a state-owned electricity distribution company, which uses criticality as a framework for exploring the technical and political choices that shape energy transition trajectories. The analysis of these three cases demonstrates that defining criticality ultimately reflects the desired expressions of sovereignty in times of crisis. More than just a technical assessment of supply risks, criticality embodies deeper struggles over how states define crises and assert sovereignty
Soutenir le patrimoine industriel et les savoir-faire locaux au service des territoires : le cas de Terre et Fils
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Exponentially fast selection of sectors for quantum trajectories beyond non demolition measurements
No full textInternational audienceWe show that, in long time, quantum trajectories select an invariant subspace of the Hilbert space of the system being indirectly measured. This selection is shown to be exponentially fast in an almost sure sense and in average. This result generalizes a known result for non demolition measurements to arbitrary repeated indirect measurements. Our proofs are based on the introduction of a deformation of the original instrument to an equivalent one with a unique invariant state
The end of dilemmas : joint U-I labs as a collective way to create open innovation in science
No full textInternational audienceWhile the benefits of university-industry collaborations (UICs) are well-documented, the mechanisms that enable these partnerships to simultaneously achieve scientific discovery and technological invention remain underexplored. This study investigates the management processes of joint university-industry (U-I) labs (Meissner et al. 2022), a distinct organizational model for UICs designed to deliver both academic and industrial impact. Drawing on 40 interviews and extensive secondary data from 13 joint U-I labs managed by the French National Centre for Scientific Research (CNRS), we identify the managerial conditions that foster an optimal balance between proximity and independence among academic and industrial stakeholders. This balance emerges as a cornerstone for leveraging mutual benefits, allowing stakeholders to sequentially draw on each other’s ideas and resources. The key management conditions include dual institutional embeddedness, annual or on-demand adjustments to the research program, proportional resource contributions, and a progressive selectivity in partner engagement through prior internships and PhD collaborations before establishing the joint lab. Together, these elements ensure that joint U-I labs mitigate typical UIC challenges such as cultural misalignment and conflicting objectives, while maintaining flexibility and fostering innovation and new scientific questions. Our findings reveal four mechanisms underlying the success of joint U-I labs: resource accumulation, administrative simplification, exploration of the unknown, and balancing proximity with stakeholder independence. These mechanisms allow labs to mobilize diverse resources, streamline collaboration processes, and create a shared yet flexible research agenda. Additionally, by fostering both cognitive and organizational proximity while preserving the independence of academic and industrial actors, joint U-I labs overcome typical challenges in UICs, such as cultural misalignment and goal divergence. This research contributes to UIC (Rybnicek and Königsgruber 2019) and the Open innovation in science (Beck et al. 2022) literature in three ways. First, it refines the understanding of managerial micro-foundations within joint U-I labs, offering insights into their unique capacity to sustain double objectives over time. Second, it highlights the importance of hybrid governance models in achieving longevity and mutual satisfaction for academic and industrial stakeholders. Finally, it expands the open innovation and science theory by presenting a framework for team-level management that balances proximity and independence at a team level. This framework transcends the use-inspired basic research model (Stokes 1997), situating U-I collaborations within the broader paradigm of Open Innovation in Science (OIS). Beck, Susanne, Carsten Bergenholtz, Marcel Bogers, Tiare-Maria Brasseur, Marie Louise Conradsen, Diletta Di Marco, Andreas P. Distel, et al. 2022. ‘The Open Innovation in Science Research Field: A Collaborative Conceptualisation Approach’. Industry and Innovation 29 (2): 136–85. https://doi.org/10.1080/13662716.2020.1792274. Meissner, Dirk, Yuan Zhou, Bruno Fischer, and Nicholas Vonortas. 2022. ‘A Multilayered Perspective on Entrepreneurial Universities: Looking into the Dynamics of Joint University-Industry Labs’. Technological Forecasting and Social Change 178 (May):121573. https://doi.org/10.1016/j.techfore.2022.121573. Rybnicek, Robert, and Roland Königsgruber. 2019. ‘What Makes Industry–University Collaboration Succeed? A Systematic Review of the Literature’. Journal of Business Economics 89 (2): 221–50. https://doi.org/10.1007/s11573-018-0916-6. Stokes, Donald E. 1997. Pasteur’s Quadrant: Basic Science and Technological Innovation. Brookings Institution Press
Living with the rare late-onset genetic disease CADASIL: Improvising “tactics” to appropriate biomedical knowledge and technology
No full textInternational audienceThis study focuses on cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a rare late-onset neurodegenerative disease of genetic origin. For CADASIL—and for other late-onset genetic conditions—genetic testing can predict whether an individual will develop the disease, even in the absence of symptoms. Multiple bodies of research in the social studies of medicine and in science and technology examine how individuals with genetic risks and diseases live through the in-between situation of being simultaneously healthy and on the cusp of ill-health. Drawing on data from interviews with 30 individuals concerned with CADASIL, we show that they do not allow themselves to be reduced to their genetic status. On the contrary, they appropriate the possibilities offered by biomedical knowledge and technology (genetic testing and reproductive technologies) to, as much as possible, control the way the disease manifests in their lives. We explore three pivotal moments or situations in the lives of these individuals: facing the possibility of genetic testing, dealing with the disease and its surveillance after the diagnosis, and becoming a parent with or without the assistance of reproductive technologies. In contrast to criticisms of geneticization, we examine how, at each of these stages, these individuals develop “tactics”—in the sense employed by de Certeau (1990)—with respect to genetics to keep the disease at arm's length and live as good a life as possible
Statically recrystallized grain size as a function of prior stored energy level in the A-286 Fe-based superalloy
No full textInternational audienceA-286 alloy is a Fe-based superalloy used in various engines and gas turbine components. During manufacturing, this alloy is submitted to a solution heat treatment that provides good formability for the subsequent deformation steps. Hence, a good control of grain size evolution is required to avoid the formation of a broad grain size distribution or the growth of abnormally large grains. In this work, a well-controlled strain gradient has been generated by means of indentation tests at room temperature. A specific strain level, calculated by finite element simulations, and the associated dislocation density estimated by the EBSD technique, lead to the activation of selective grain growth during heat treatment after a given incubation time. This study on cold-deformed A-286 alloy allowed a quantitative assessment of recrystallized grain size dependence on stored energy and the identification of the critical stored energy value for grain nucleation, providing a better understanding of A-286 static recrystallization behavior