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A Modelling-Based Analysis Of Extreme Wave Setup In A Fringing Coral Reef
No full textInternational audienceCoastal hazards in tropical islands are likely to increase under the combined effects of sea-level rise, coral reef degradation and the potential intensification of extreme cyclones. In volcanic islands bordered by deep waters, storm surges are primarily driven by atmospheric pressure gradients and the development of a wave setup in the nearshore, which results from wave dissipation. Recent studies on the hydrodynamics of reef lagoon systems have demonstrated that the mean wave-driven circulation can either increase or decrease the wave setup along the shoreline, depending on the system configuration. This study combines the analysis of a unique dataset capturing a paroxysmal event (significant height exceeding 7 m at the breaking point) with phase-averaged numerical modelling to provide further insight on wave setup development in fringing reef environments under extreme conditions. When considering a 2DH modelling approach, the largest wave setup is underestimated by over 40%. Wave setup predictions are partly improved when using fully-coupled 3D runs, due to the representation of the vertical mixing and the horizontal and vertical advections associated with the intense hydrodynamic circulation that takes place in the surfzone.</div
Semakin banyak menguasai bahasa, semakin kecil risiko penuaan dini
No full textInternational audienceAgeing is accelerated by zombie cells and stress, but can be slowed down through physical and mental activity and brain stimulation. Multilingualism (the use of multiple languages) can increase the brain's cognitive reserve. Staying young by learning multiple languages is only possible if there is internal motivation and a conducive environment.Le vieillissement est accéléré par les cellules zombies et le stress, mais il peut être ralenti par l'activité physique, mentale et la stimulation cérébrale. Le multilinguisme (l'utilisation de plusieurs langues) peut améliorer les réserves cognitives du cerveau. Rester jeune grâce à l'apprentissage de plusieurs langues n'est possible qu'avec une motivation interne et un environnement propice.Penuaan dipercepat oleh sel-sel zombi dan stres, tetapi dapat diperlambat melalui aktivitas fisik, mental, dan stimulasi otak. Multilingualisme (penggunaan banyak bahasa) dapat meningkatkan cadangan kognitif otak. Awet muda karena belajar banyak bahasa hanya mungkin terjadi jika ada motivasi internal dan lingkungan yang kondusif
Methodologies and evaluations of energy flexibility for clusters of buildings
No full textDecarbonization of the electricity grid and the electrification of transport, heat and industry related energy consumption are at the center of many governments’ policies to reach ambitious targets to reduce green-house gas emissions. The integration of variable renewable energy sources into power grids and the growing electricity demand reinforce the need for energy flexibility: buildings should adapt their energy demand and/or production to weather conditions, to their users’ needs, and to the requirements of the electricity grid.This report summarizes the work performed within Annex 82, which includes the review of state-of-the-art methodologies for the evaluation of energy flexibility at the building cluster level. Addressing energy flexibility at the building cluster level remains a challenge, with technical and non-technical barriers to adoption (non) technical barriers are discussed in more detail in another report of Annex 82, which presents recommendations for policy makers and government entities). Technical barriers for the early planning, design, and operation phases include the development of integrated modelling tools, control strategies addressing the buildingcluster or portfolio level, and the development of quantitative methodologies and indicators. More effective strategies and policies must be developed to design and operate resilient and sustainable communities.Dominant factors for energy flexibility are related to occupants, building characteristics, energy systems and storage, control systems, and external factors (e.g., weather and market).Research teams involved in Annex 82 also investigated building-grid interaction signals, a generalization of “price signals” or “penalty signals”. These signals must be aligned with the demand response objectives forthe correct use of available energy flexibility. To characterize this flexibility, building load prediction plays a crucial role in the evaluation of baseline scenarios and available demand-response potential. Key performance indicators for energy flexibility were also assessed and developed within the Annex. In particular, the flexibility index and flexibility function were tested and improved.One of the main collaborative efforts within Annex 82 consisted in the “Common Exercise”, which aimed at enabling various research groups to tackle a joint challenge by specifying common boundary conditions, while allowing teams to use their own simulation tools, control algorithms, and datasets. A common building- grid interaction signal (a “price signal” in this case) was defined and all teams were asked to select a building portfolio and to assess the energy flexibility at the portfolio level. Common performance indicators were assessed by all teams, which allowed a comparison across widely different building portfolios and climate conditions. Both reactive and predictive strategies led to a worsening of monitored metrics such as the load factor or system ramping and generate significant rebounds (as well as “prebounds”) before and/or after the flexibility events. All results illustrate the need for mitigation strategies to obtain a positive impact of local energy flexibility strategies at the global (i.e., portfolio) level. Energy flexibility strategies that strictly maintain an equivalent comfort level also led to an overall energy increase, which may be justified by the variable “value” of electricity, whether it is assessed by cost or GHG emissions, for example.Finally, Annex 82 work highlighted the scarcity of field studies demonstrating energy flexibility at the building cluster or portfolio level. Two field implementations conducted within Annex 82 are described in the report: the use of a novel control algorithm (signal matrix model predictive control) to control space heating, domestic hot water heating, and a stationary battery, and the coordinated use of the different assets in a fully equipped occupied building for flexibility. Annex 82 has advanced the state-of-the-art in methods to characterize, model, and harness energy flexibility of building clusters and portfolios, which will enable more demonstration projects to confirm the promising results of those two field studies
Les humanités océanes. Entretien avec Laurent Vidal
No full textInternational audienceSince 1989, historian Laurent Vidal has been researching the history of Brazil and, more broadly, transatlantic cultural exchanges. Having worked in particular on urban formations, as illustrated by his book Mazagão, la ville qui traversa l’Atlantique : du Maroc à l’Amazonie (1769-1783) published by Flammarion in 2008, he has gradually developed a reflection on the relationship with time, waiting and social rhythms, as in his book Les Hommes lents, résister à la modernité published in 2020. Professor of History at the University of La Rochelle and Director of Research at the Institut des Hautes Études d'Amérique Latine (University of Paris III), he became President of the Centre Intermondes in 2020. Founded in La Rochelle at the very beginning of the 21st century on the initiative of sociologist Jean Duvignaud, this cultural structure has developed, from this former slave-trading port, exchanges on all continents aimed, through artistic residencies, at publicly and anthropologically reinterrogating creation without opposing it to heritage. This is how, from 2020 onwards, the project to become an ethnopole is maturing, taking on the poetic and seminal name of Humanités océanes. As the latest ethnopôle, it focuses on issues relating to cultural cross-fertilization and circulation, the imaginary of inhabitation and the ecological condition, artistic creation and the re-use of heritage in a post-colonial context. In this interview, Laurent Vidal, the Centre's director, talks to Thomas Mouzard, head of the French Ministry of Culture's ethnopole network, about the genesis of the Centre Intermondes-Humanités océanes, and then reveals the anthropological, cultural and scientific perspectives it has opened up.L’historien Laurent Vidal mène depuis 1989 des recherches sur l’histoire du Brésil et plus largement sur les échanges culturels transatlantiques. Ayant en particulier travaillé sur les formations urbaines, comme en témoigne son ouvrage Mazagão, la ville qui traversa l’Atlantique : du Maroc à l’Amazonie (1769–1783) publié chez Flammarion en 2008, il a progressivement développé une réflexion sur le rapport au temps, l’attente, les rythmes sociaux, comme dans son livre Les Hommes lents, résister à la modernité paru en 2020. Professeur des universités en histoire à l’université de La Rochelle et directeur de recherche à l’Institut des hautes études d’Amérique latine (université de Paris III), il devient président du Centre Intermondes en 2020. Fondée à La Rochelle au tout début du XXIe siècle à l’initiative du sociologue Jean Duvignaud, cette structure culturelle a développé, depuis cet ancien port de traite esclavagiste, des échanges sur tous les continents visant, par des résidences artistiques, à réinterroger publiquement et anthropologiquement la création sans l’opposer au patrimoine. C’est ainsi que dès 2020 le projet d’une labélisation en ethnopôle mûrit, jusqu’à prendre le nom poétique à la portée séminale d’Humanités océanes. Dernier né des ethnopôles, il intervient notamment sur les questions liées au métissage et aux circulations culturelles, à l’imaginaire de l’habiter et à la condition écologique, aux créations artistiques et aux réemplois des patrimoines en contexte postcolonial. Dans cet entretien, Laurent Vidal, son directeur, revient, avec Thomas Mouzard, responsable du réseau des ethnopôles au ministère de la Culture, sur la genèse du Centre Intermondes-Humanités océanes, puis dévoile les perspectives anthropologiques, culturelles et scientifiques, ainsi ouvertes
Measuring Ocean Surface Waves
No full textPropagating waves on the surface of the ocean can be represented as a stochastic process, whose statistics are characterized by a spectrum. Measuring the wave spectrum, and quantities derived from the spectrum, are reviewed here. Observation begins by sensing some property of the sea surface over space and/or time. Visual observations, collected routinely since the mid 18th century, comprise the longerest running wave record. Measurement methods in the nearshore are advancing, including traditional methods using pressure and acoustic sensing, but also newer methods such as distributed acoustic sensing and lidar. Detailed, small scale wave physics can now be explored with measurement techniques using light, including stereo-imaging and polarimatry. The decrease in size, cost, and power consumption of microelectronics has propagated through to ocean wave instrumentation, most notably in wave buoys. Global networks of freely drifting miniature wave buoys offer novel observational power. Remote sensing techniques based on radar and lidar continue to evolve, and are widely deployed from land and on ships, aircraft, autonomous vehicles, and satellites. Spaceborne altimeters form one of the most important records of wave height, and a suite of suite of new spaceborne sensors are observing directional spectra across the globe with sampling akin to traditional altimetry. Aircraft and autonomous systems are providing strategic sampling capabilities, whether for detailed process studies or accessing extreme storm environments. The quality and quantity of ocean wave measurements has never been greater. This review will help you make sense of it all
Design and experimental validation of an urban microclimate tool integrating indoor-outdoor detailed longwave radiative fluxes at district scale
No full textInternational audienceNumerical simulation is a powerful tool for assessing the causes of an Urban Heat Island (UHI) effect or quantifying the impact of mitigation solutions on outdoor and indoor thermal comfort. For that purpose, several models have been developed at the district scale. At this scale, the outside surface energy budget is detailed, however building models are very simplified and considered as a boundary condition of the district scale model. This shortcoming inhibits the opportunity to investigate the effect of urban microclimate on the inside building conditions. The aim of this work is to improve the representation of the physical phenomena involved in the building models of a district model. For that purpose, the model integrates inside and outside fully detailed long-wave radiative flux. The numerical model is based on finite differences to solve conduction through all the surfaces and the radiosity method to solve long-wave radiative heat fluxes inside and outside. Calculated temperatures and heat fluxes are evaluated with respect to in situ measurements from an experimental demonstrator over 14 sensors and a 24-day period. Results are also compared to state-of-the-art models simulation tool show improvement of the RMSE of 0.9 • C to 2.1 • C on the surface temperature modeled
The Chemopreventive and Antitumor Potential of Cranberry ( Vaccinium Macrocarpon Aiton) in Gastrointestinal Cancers: A Review of Molecular Mechanisms, Preclinical Evidence, and Commercial Perspectives
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Étude multi-échelle de l’implication de la plasticité et de la nature des joints dans les mécanismes de rupture fragile assistée par l’hydrogène dans le nickel pur
No full textHydrogen, increasingly being used as an alternative energy source, can lead to significant material degradation, particularly in nickel, which is widely used in superalloys. This phenomenon, known as hydrogen embrittlement, arises primarily from the interaction of hydrogen as a solute with metallurgical heterogeneities, which tend to accumulate at grain boundaries. These interactions negatively impact the mechanical properties of the material, potentially causing premature fractures with an intergranular nature, combined with plasticity mechanisms, resulting from a reduction in the cohesive energy of grain boundaries under the influence of hydrogen. For deeper understanding of hydrogen interaction with microstructural heterogeneities, a multi-scale study is being conducted on various types of nickel microstructures. The research is focused on the plasticity mechanisms that contribute to the degradation of nickel, specifically exploring the hardening and softening effects induced by hydrogen consequence on intergranular fracture. The study will investigate three types of nickel microstructures: single crystals, bicrystals, and polycrystals with experimental approach. The first part of this study will concentrate on nickel single crystals to avoid any influence of grain boundaries, allowing for a focused analysis of hydrogen effect on different crystallographic orientations. Both elastic and plastic properties will be assessed using nanoindentation (at the microscale) and tensile testing (at the macroscale). This phase aims to provide insights into the anisotropic nature of hydrogen diffusion and its impact on damage, by evaluating the elastic modulus of nickel in each orientation and analyzing dislocation activity during plastic deformation. The second part will focus on nickel bicrystals, examining four specific types of grain boundaries. Tensile tests will be employed to study the contribution of grain boundaries to the damage mechanisms by evaluating defects caused by hydrogen near these boundaries in relation with a potential transmission of slip across grain boundary. Additionally, work hardening and dislocation activity will be discussed to further elucidate the effects of hydrogen. The final part will address polycrystals, where the combined effects of different grain boundary characteristics and grain orientations will be studied. Various hydrogen concentrations will be explored to understand their impact on the degree of embrittlement in relation with the fraction of Coincident Site Lattice grain boundaries. This part of the study will examine work hardening, damage modes, and dislocation patterns, with the aim of providing elements of understanding into intergranular crack initiation propagation and fracture induced by hydrogen.L'hydrogène, de plus en plus utilisé comme source d'énergie alternative, peut entraîner une dégradation significative des matériaux, en particulier dans le nickel, qui est largement utilisé dans les superalliages. Ce phénomène, connu sous le nom de fragilisation par l'hydrogène, provient principalement de l'interaction de l'hydrogène en tant que soluté avec les hétérogénéités métallurgiques, qui ont tendance à s'accumuler aux joints de grains. Ces interactions altèrent les propriétés mécaniques du matériau, pouvant provoquer des fractures prématurées de nature intergranulaire, combinées à des mécanismes de plasticité, résultant d'une diminution de l'énergie de cohésion des joints de grains sous l'influence de l'hydrogène. Pour approfondir la compréhension de l'interaction de l'hydrogène avec les hétérogénéités microstructurales, une étude multi-échelle est menée sur différents types de microstructures du nickel. Cette recherche se concentre sur les mécanismes de plasticité qui contribuent à la dégradation du nickel, en explorant spécifiquement les effets de durcissement et de ramollissement induits par l'hydrogène et leurs conséquences sur la fracture intergranulaire. L'étude portera sur trois types de microstructures du nickel : monocristaux, bicristaux et polycristaux, avec une approche expérimentale. La première partie de cette étude se concentrera sur les monocristaux de nickel afin d'éliminer toute influence des joints de grains, permettant ainsi une analyse ciblée des effets de l'hydrogène sur différentes orientations cristallographiques. Les propriétés élastiques et plastiques seront évaluées à l'aide de la nanoindentation (à l'échelle microscopique) et d'essais de traction (à l'échelle macroscopique). Cette phase vise à fournir des informations sur la nature anisotrope de la diffusion de l'hydrogène et son impact sur les dommages, en évaluant le module élastique du nickel dans chaque orientation et en analysant l'activité des dislocations lors de la déformation plastique. La deuxième partie se concentrera sur les bicristaux de nickel, en examinant quatre types spécifiques de joints de grains. Des essais de traction seront réalisés pour étudier la contribution des joints de grains aux mécanismes de dégradation en évaluant les défauts causés par l'hydrogène à proximité de ces joints, en lien avec une éventuelle transmission des glissements à travers les joints de grains. De plus, le durcissement et l'activité des dislocations seront discutés pour mieux comprendre les effets de l'hydrogène. La dernière partie portera sur les polycristaux, où les effets combinés des différentes caractéristiques des joints de grains et des orientations des grains seront étudiés. Diverses concentrations d'hydrogène seront explorées pour comprendre leur impact sur le degré de fragilisation en relation avec la fraction des joints de grains de type réseau de sites coïncidents (CSL). Cette partie de l'étude examinera le durcissement, les modes de dégradation et les motifs de dislocations, dans le but de fournir des éléments de compréhension sur l'initiation, la propagation des fissures intergranulaires, et la fracture induite par l'hydrogène
An Operational Quantum Information Framework for Experimental Studies on Color Perception
No full textInternational audienceStarting from the foundational axiomatization of the perceptual color space initiated by Schrödinger in 1920 and eventually refined by Resnikoff in 1974, Berthier, Provenzi and their collaborators have recently proposed a reformulation of perceptual color attributes within the framework of quantum information. Their work is based on the Jordan algebra formalism of quantum theories and, more specifically, on a quantum system described by a spin factor over the field of real numbers. This theoretical framework is not that of ordinary quantum mechanics, mainly because it requires dealing with rebits, whereas the latter uses qubits. The aim of this paper is to show that this difference in no way hinders the implementation of experimental protocols for testing the validity of the predictions of the color perception model. In particular, we show how to compute the quantum information based perceptual attributes of perceived colors in terms of qubit density matrices