Simulations multi-agents multi-niveaux : quatre patterns de conception

International audienceThis paper introduces four design patterns, drawn from minimal typical situations found in the literature, and meant to systematize and simplify the design of multilevel multiagent simulations. Such simulations aim at handling entities which belong to different, but coupled, abstraction or organization levels. For each pattern, we present use cases and associated data structures and algorithms. For genericity purposes, these patterns rely upon a unified description of the capabilities for action and change of the agents. Thus, we propose a precise conceptual and operational frame for the designers of multilevel simulations.Cet article introduit quatre patterns de conception, définis à partir de l'identification de "situation-types" minimales rencontrées dans la littérature et destinés à systématiser et simplifier la conception de simulations multi-agents multi-niveaux. Ces simulations ont pour but de gérer des entités appartenant à des niveaux d'abstraction ou d'organisation différents mais couplés. Pour chaque pattern, nous présentons des cas d'utilisation ainsi que les structures de données et algorithmes associés. À des fins de généricité, ces patterns font appel à une description unifiée des capacités d'action et d'évolution des agents. Nous proposons ainsi un cadre conceptuel et opérationnel précis pour les concepteurs de simulations multi-niveaux

Numerical simulation and experimental validation of gap supported tube subjected to fluid-elastic coupling forces for hybrid characterization tests

International audienceIn steam generators, the primary loop tubes are subjected to fluid coupling forces and impacts. Understanding the behavior of these tubes is crucial when designing steam generators. In fact, it can afford an optimization of produced energy and a long average life of the structure. Up to now, the effect of the coupling forces on structural behavior was identified on reduced scale structures. Thus, the aim of our research is to give a better understanding of stabilizing effects of shock and coupling with fluid elastic forces. In order to validate numerical investigations, since fluid elastic forces are difficult simulate and expensive to reproduce experimentally, the fluid coupling forces will be assumed to be represented using velocity dependant (fluid and structure) damping and stiffness matrices, and experimentally reproduced using active vibration control into hybrid experimental tests to simplify big structure characterization. In this paper, a method for modeling the structure behavior in order to estimate the effects of the coupling between the fluid elastic forces and impacts is presented. This strategy implies lower costs and avoids difficulties associated to the case of fluid in the experiments. This model will be implemented in the active control loop in the next step of the study

Robust expansion of experimental mode shapes under epistemic uncertainties

International audienceImportant variations in response behaviors of power plant generators are observed in a population of nominally identica installations due to numerous and significant sources of variability. As a result, it proves to be extremely difficult to implement a predictive and reliable physics-based model. The present study attempts to leverage an existing non validated numerical model to reconstruct information on unobserved degrees of freedom based on the results of modal tests. An expansion method is proposed based on the concept of the constitutive relation error (CRE). This method leads to minimization of an energy-based functional that takes into account both errors in the model and in the test data. Due to lack of knowledge, commonplace in this kind of complex system, the expansion will be presented in the framework of robust approach. More precisely, the first objective of this article is to assess the robustness of the mode shape expansion in presence of large epistemic uncertainties that are represented as info-gap models. Secondly, a strategy will be presented to maximize the robustness of the expansion by appropriately selecting the model decision variables for a given horizon of uncertainty. The proposed methodology is illustrated on simple academic test cases

Observation of the Unconventional Photon Blockade in the Microwave Domain

We have observed the unconventional photon blockade effect for microwave photons using two coupled superconducting resonators. As opposed to the conventional blockade, only weakly nonlinear resonators are required. The blockade is revealed through measurements of the second order correlation function $g^{(2)}(t)$ of the microwave field inside one of the two resonators. The lowest measured value of $g^{(2)}(0)$ is 0.4 for a resonator population of approximately $10^{-2}$ photons. The time evolution of $g^{(2)}(t)$ exhibits an oscillatory behavior, which is characteristic of the unconventional photon blockade

Quantum bath engineering of a high impedance microwave mode through quasiparticle tunneling

We demonstrate a new approach to dissipation engineering in microwave quantum optics. For a single mode, dissipation usually corresponds to quantum jumps, where photons are lost one by one. Here, we are able to tune the minimal number of lost photons per jump to be two (or more) with a simple dc voltage. As a consequence, different quantum states experience different dissipation. Causality implies that the states must also experience different energy shifts. Our measurements of these Lamb shifts are in good agreement with the predictions of the Kramers-Kronig relations for single quantum states in a regime of highly non-linear bath coupling. This work opens new possibilities for quantum state manipulation in circuit QED, without relying on the Josephson effect

Vortex merger near a topographic slope in a homogeneous rotating fluid

This work is a contribution to the PHYSINDIEN research program. It was supported by CNRS-RFBR contract PRC 1069/16-55-150001.The effect of a bottom slope on the merger of two identical Rankine vortices is investigated in a two dimensional, quasi-geostrophic, incompressible fluid. When two cyclones initially lie parallel to the slope, and more than two vortex diameters away from the slope, the critical merger distance is unchanged. When the cyclones are closer to the slope, they can merge at larger distances, but they lose more mass into filaments, thus weakening the efficiency of merger. Several effects account for this: the topographic Rossby wave advects the cyclones, reduces their mutual distance and deforms them. This along shelf wave breaks into filaments and into secondary vortices which shear out the initial cyclones. The global motion of fluid towards the shallow domain and the erosion of the two cyclones are confirmed by the evolution of particles seeded both in the cyclone sand near the topographic slope. The addition of tracer to the flow indicates that diffusion is ballistic at early times. For two anticyclones, merger is also facilitated because one vortex is ejected offshore towards the other, via coupling with a topographic cyclone. Again two anticyclones can merge at large distance but they are eroded in the process. Finally, for taller topographies, the critical merger distance is again increased and the topographic influence can scatter or completely erode one of the two initial cyclones. Conclusions are drawn on possible improvements of the model configuration for an application to the ocean.PostprintPeer reviewe

The reuniens and rhomboid nuclei are necessary for contextual fear memory persistence in rats.

Memory persistence refers to the process by which a temporary, labile memory is transformed into a stable and long-lasting state. This process involves a reorganization of brain networks at systems level, which requires functional interactions between the hippocampus (HP) and medial prefrontal cortex (mPFC). The reuniens (Re) and rhomboid (Rh) nuclei of the ventral midline thalamus are bidirectionally connected with both regions, and we previously demonstrated their crucial role in spatial memory persistence. We now investigated, in male rats, whether specific manipulations of ReRh activity also affected contextual and cued fear memory persistence. We showed that the permanent ReRh lesion impaired remote, but not recent contextual fear memory. Tone-cued recent and remote fear memory were spared by the lesion. In intact rats, acute chemogenetic ReRh inhibition conducted before recall of either recent or remote contextual fear memories produced no effect, indicating that the ReRh nuclei are not required for retrieval of such memories. This was also suggested by a functional cellular imaging approach, as retrieval did not alter c-fos expression in the ReRh. Collectively, these data are compatible with a role for the ReRh in 'off-line' consolidation of a contextual fear memory and support the crucial importance of ventral midline thalamic nuclei in systems consolidation of memories.journal article2020 Apr2020 03 07importe

Enabling planetary science across light-years. Ariel Definition Study Report

Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm ellipse) and two separate instruments (FGS and AIRS) covering simultaneously 0.5-7.8 micron spectral range. The satellite is best placed into an L2 orbit to maximise the thermal stability and the field of regard. The payload module is passively cooled via a series of V-Groove radiators; the detectors for the AIRS are the only items that require active cooling via an active Ne JT cooler. The Ariel payload is developed by a consortium of more than 50 institutes from 16 ESA countries, which include the UK, France, Italy, Belgium, Poland, Spain, Austria, Denmark, Ireland, Portugal, Czech Republic, Hungary, the Netherlands, Sweden, Norway, Estonia, and a NASA contribution