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Partition Strategies for the Maker–Breaker Domination Game
No full textInternational audienceThe Maker-Breaker domination game is a positional game played on a graph by two players called Dominator and Staller. The players alternately select a vertex of the graph that has not yet been chosen. Dominator wins if at some point the vertices she has chosen form a dominating set of the graph. Staller wins if Dominator cannot form a dominating set. Deciding if Dominator has a winning strategy has been shown to be a PSPACE-complete problem even when restricted to chordal or bipartite graphs. In this paper, we consider strategies for Dominator based on partitions of the graph into basic subgraphs where Dominator wins as the second player. Using partitions into cycles and edges (also called perfect [1,2]factors), we show that Dominator always wins in regular graphs and that deciding whether Dominator has a winning strategy as a second player can be computed in polynomial time for outerplanar and block graphs. We then study partitions into subgraphs with two universal vertices, which is equivalent to considering the existence of pairing dominating sets with adjacent pairs. We show that in interval graphs, Dominator wins if and only if such a partition exists. In particular, this implies that deciding whether Dominator has a winning strategy playing second is in NP for interval graphs. We finally provide an algorithm in n k+3 for interval graphs with at most k nested intervals.</div
Development and validation of a self- and hetero-assessment questionnaire for complaints about anomia: S.H.Q.A.
No full textInternational audienc
The Sikkim flood of October 2023: Drivers, causes and impacts of a multihazard cascade
No full textInternational audienceOn 3 October 2023, a multihazard cascade in the Sikkim Himalaya, India, was triggered by 14.7 million m 3 of frozen lateral moraine collapsing into South Lhonak Lake, generating an ~20 m tsunami-like impact wave, breaching the moraine, and draining ~50 million m 3 of water. The ensuing Glacial Lake Outburst Flood (GLOF) eroded ~270 million m 3 of sediment, which overwhelmed infrastructure, including hydropower installations along the Teesta River. The physical scale and human and economic impact of this event prompts urgent reflection on the role of climate change and human activities in exacerbating such disasters. Insights into multihazard evolution are pivotal for informing policy development, enhancing Early Warning Systems (EWS), and spurring paradigm shifts in GLOF risk management strategies in the Himalaya and other mountain environments
Rédiger un compromis de vente immobilière
No full textFiche pratique présentant les grandes étapes de la conclusion de la promesse synallagmatique de vente immobilièr
VOGTNet: Variational Optimization-Guided Two-Stage Network for Multispectral and Panchromatic Image Fusion
No full textInternational audienceMultispectral image (MS) and panchromatic image (PAN) fusion, which is also named as multispectral pansharpening, aims to obtain MS with high spatial resolution and high spectral resolution. However, due to the usual neglect of noise and blur generated in the imaging and transmission phases of data during training, many deep learning (DL) pansharpening methods fail to perform on the dataset containing noise and blur. To tackle this problem, a variational optimization-guided two-stage network (VOGTNet) for multispectral pansharpening is proposed in this work, and the performance of variational optimization (VO)-based pansharpening methods relies on prior information and estimates of spatial-spectral degradation from the target image to other two original images. Concretely, we propose a dual-branch fusion network (DBFN) based on supervised learning and train it by using the datasets containing noise and blur to generate the prior fusion result as the prior information that can remove noise and blur in the initial stage. Subsequently, we exploit the estimated spectral response function (SRF) and point spread function (PSF) to simulate the process of spatial-spectral degradation, respectively, thereby making the prior fusion result and the adaptive recovery model (ARM) jointly perform unsupervised learning on the original dataset to restore more image details and results in the generation of the high-resolution MSs in the second stage. Experimental results indicate that the proposed VOGTNet improves pansharpening performance and shows strong robustness against noise and blur. Furthermore, the proposed VOGTNet can be extended to be a general pansharpening framework, which can improve the ability to resist noise and blur of other supervised learning-based pansharpening methods. The source code is available at https://github.com/HZC-1998/VOGTNet
Stability of LiF Deposited by ALD on High-Voltage Spinel/Polyimide Composite Electrodes
No full textInternational audienceLi-Ni-Mn-O spinel cathode materials operating at ∼5 V vs Li+/Li appear to be very interesting alternatives to Co-containing layered materials in terms of rate capability, energy and power densities, and sustainability of material resources. Nevertheless, their high operating voltage, which has been an asset to date, does not allow them to be used with conventional carbonate-based electrolytes. The latter undergoes spontaneous oxidation when in contact with the charged electrode, resulting in a reduction of the cathode material, an imbalance in the Li-ion system, and a subsequent rapid loss of capacity. This incompatibility could be overcome by creating a stable, electronically insulating solid interphase at the surface of the composite electrode. Here, we report the direct deposition of lithium fluoride (LiF) on LNMO electrodes by atomic layer deposition (ALD). LiF prepared with a specific combination of precursors (lithium bis(trimethylsilyl)amide and titanium tetrafluoride) has a total impurity content of less than 2% in the bulk. In addition, to enable direct coating by ALD on the positive electrode, a commonly used binder (polyvinylidene fluoride) was replaced with polyimide (PI), a more thermally stable and nonfluorinated polymer. Using X-ray photoelectron spectroscopy (XPS) and electrochemical analysis, we demonstrate the excellent thermal stability of this LNMO/PI electrode up to 300 °C as well as its electrochemical and chemical stability in a standard carbonate electrolyte. Electrochemical data show that LiF extends the cycle life of the LNMO/PI half-cell at a high C-rate (1C). The LiF layer has been proven to be stable on the pristine electrode upon prolonged exposure to the electrolyte. However, when charged at a low C-rate, the layer exhibits a tendency to disappear. The reasons for this behavior are not yet clear but could be linked to the degradation reactions in the electrolyte or to the local concentration changes
Interaction between spherical dielectric particles and surface integrated waveguides: a semi-analytical complex angle approach
No full textInternational audienceA trend in optical biosensors concerns the development of integrated photonic lab-on-chips to develop compact and portable solutions. These sensors take advantage of the enhanced sensitivity of microstructures and rely on the modulation of light properties such as intensity, phase or wavelength. Detection by evanescent coupling of microparticles selectively trapped at the surface of an optical waveguide is a common solution. Many microparticles can be approximated by spherical objects with a complex refractive index different from the medium one. In this case, Mie theory is well-known for describing how they scatter light coming from a plane wave. Less obvious is the description of the light scattering induced by this microparticles on a light propagated in an integrated waveguide. We propose here a semi-analytical modeling based on a complex angle approach to evaluate the interaction between a surface guided mode and dielectric spheres placed on top of the waveguide. In this approach, time-saving with respect to a 3D simulation, an evanescent incident wave is described as a plane wave that is geometrically rotated by a complex angle. We show how it can be used to evaluate the waveguide losses induced by dielectric microparticles placed close to its surface. We then apply this model to a sensor where polystyrene microbeads are selectively trapped on top of a glass surface waveguide thanks to dielectrophoresis
Caractérisation des sites de reproduction de l'Omble chevalier (Salvelinus umbla)
No full textPartie 1 : Faisabilité de la caractérisation des sites de reproduction de l'Omble chevalier à l'aide d'un ROV -Frayère du Bouveret (Léman) Partie 2 : Analyse de la corrélation entre la fréquentation de l'Omble chevalier et la température de l'eau sur l'omblière d'Yvoire sur le Léma
On the reliability and impact of a reference electrode for lithium-ion battery during cycling
No full textInternational audienceReducing greenhouse gas emissions through the widespread adoption of electric vehicles remains a challenge, notably because of the long charging time of lithium-ion batteries. Indeed, carmakers restrict the charging performance of their cells to avoid lithium plating: a parasitic reaction occurring during charge that strongly affects the battery's durability. To improve these charging performances while ensuring batteries’ durability, it becomes essential to detect the lithium plating phenomenon. In theory, a reference electrode (RE) could be the ideal solution, as the implementation of a third electrode in the cell enables constant tracking of the negative electrode potential and thus detects when it falls under 0 V vs. Li+/Li (thermodynamic condition for lithium plating [1]). However, the reliability of REs and their impact on battery cycling are usually overlooked in the literature. The main limitation of REs is their lack of long-term stabilities which limits the lithium plating tracking to a few cycles and therefore cannot be implemented in commercial systems. For instance, McTurk et al. reported a maximum of 20 cycles at C/10 rate before a significant drift of their lithium metal RE potential [2] which is insufficient to quantify the lithium plating impact on battery durability. Recently, REs made of lithium intercalated oxides have become increasingly popular as they demonstrated promising stability for long-term studies such as LiFePO4 (LFP) which lasted more than 1000 h at C/5 [3]. In addition to their low lifespan, the non-negligeable size of REs compared to the lithium ions flow in the liquid electrolyte hinders the cell functioning. For instance, Li et al. reported a blocking effect from the RE which resulted in a heterogenous delithiation/lithiation of the positive/negative electrode near the RE and a tendency to overestimate the lithium plating mechanism [4]. Alternately, some studies placed their RE outside the electrochemical core to limit cell disturbance, but have experienced measurement artifacts [5]. In this work, a third electrode set-up consisting of a LFP RE implemented in a 12 mAh lithium-ion pouch cell with NMC and graphite electrodes will be presented. This setup has been characterized by high resolution operando X-ray diffraction (XRD) using synchrotron large scale facility (BM02 beamline at the European Synchrotron Radiation Facility). Based on the high spatial and temporal resolution offered by the beamline (Ø60 µm spot & 1 s of acquisition), the local phase transitions within electrodes (positive, negative, and reference) have been monitored at several C-rates and at different cell locations. Indeed, the acquisition of multiple diffractograms at different locations of the cell during cycling enables to quantify:-The impact of the RE onto graphite lithiation as a function of the cell C-rate.-The evolution of the RE chemical composition during cycling and therefore the stability of the RE potential over time
Poljes, a pre-structuration of the hydrosystems in plateau karsts, the example of the Jura mountain (Fr)
No full textInternational audienceThe aim of this work is to analyze - through the prism of poljes - the development of karst networks and the organization of underground drainage in the case of plateau karsts. The methodology combines various approaches: i) surface morphology, ii) speleogenesis and iii) hydrogeology. The study site is the Loue basin, located in the french Jura Mountains. It is a typical plateau karsts, with its high karstification degree (around a hundred karst networks over 100 m, several karst springs with an average flow superior to 1 m3/s), and its extensive hydrogeological knowledge of karst hydrosystems (several hundred dye tracer tests available). First, a detailed surface morphological mapping has shown that the current plateaus correspond to ancient depressions with relatively flat, elliptical bottoms, and large extension (~ 400 km²). These plateaus are enclosed between the raised hydrological barriers of anticlines (fold systems). We interpreted these depressions as paleo-poljes. Currently perched 150 m above the base level, they only have a residual hydrological functioning, i.e. the lowest of them are subject to occasional flooding by exceeding the infiltration capacity of the ponors. Second, the analysis of numerous dye tracer tests within the largest karst hydrosystems has enabled us to determine their current recharge area. A strong spatial correlation between the geometry of the recharge area and the paleo-poljes suggests that the poljes plays a pre-structuring role in the organisation of the underground drainage. Third, the analysis of the horizontal galleries (relative altitude and endokarst forms) shows several significant levels and different speleogenetic processes (paragenesis, alteration) that can be linked to ancient local base levels contemporary of the hydrological functioning of the paleo-poljes (regular and long periods of flooding). Finally, our results enable us to propose a new conceptual model of plateau karsts in the Jura Massif, highlighting the role of poljes in karstogenesis and in the hydrogeological compartmentation of current hydrosystems