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International audience; In this paper, we identify several challenges and opportunities opened to agent and multiagent systems, in the domain of Earth observation constellations. While mono-satellite and small constellations have been largely studied, recent developments of next generation satellites open novel challenges and new tracks for research. We focus here on three important categories of challenges that manifest in this application field. The first one concerns the configuration of a constellation of satellites and the set of ground stations used to operate it, potentially owned by different actors. The question is about how to dimension and how to position the satellites over a set of orbits, and the related ground stations, to provide a better service and coordination. The second category regards offline planning and scheduling problems, which consists in finding solution methods to schedule observation and upload/download tasks over the constellation. Finally, the third category addresses the design of efficient and reactive online operation methods as to adapt and repair schedules in dynamics settings. Being naturally distributed and composed of multiple entities and users, these various problems clearly fit the multiagent paradigm, and may challenge researchers for many years.

The stability of a spacecraft’s Electrical Power System (EPS) is of the utmost importance as the success of the entire mission relies on it. Its aim is to generate, condition, store and distribute the energy to the whole system in a particularly isolated and hostile environment. These important constraints and the resulting need for robustness and reliability, have shaped the EPS into a very high efficiency system, electrically speaking. However, the space industry is changing and we are witnessing its digital and industrial revolution in the same time. This trend, called New Space, brings new challenges but also opportunities to rethink the different systems and give them new features. In term of EPS, this allows to give modularity, flexibility and scalability to the system and thus respond to the constraints imposed by Lunar or Martian base projects that conventional systems cannot do. In this paper, a novel EPS architecture is proposed and analyzed using state-plane analysis techniques. The stability of various equilibrium points and the transient response of the system are also evaluated. The large-signal behavior of the different modules is then determined in view of power and energy management stability.

This paper presents a comparison of three control schemes applied on the commercially available TALOS Humanoid Robot. The aim is to highlight the advantages and drawbacks of each model applied on three locomotion problems: walking on flat and non-flat terrain and climbing stairs. The different models are based on position control (first and second models) or torque control (third model). The first one uses a hierarchical quadratic program at velocity level. The second one employs a weighted quadratic program named Task Space Inverse Dynamic (TSID) at acceleration level. Finally, the last one also uses TSID but at torque level. The controllers performances are compared in simulation, using Gazebo, on the accuracy of their tracking, their energy consumption and their computational time execution.

Full list of authors: Morgado, B. E.; Sicardy, B.; Braga-Ribas, F.; Desmars, J.; Gomes-Júnior, A. R.; Bérard, D.; Leiva, R.; Ortiz, J. L.; Vieira-Martins, R.; Benedetti-Rossi, G.; Santos-Sanz, P.; Camargo, J. I. B.; Duffard, R.; Rommel, F. L.; Assafin, M.; Boufleur, R. C.; Colas, F.; Kretlow, M.; Beisker, W.; Sfair, R.; Snodgrass, C.; Morales, N.; Fernández-Valenzuela, E.; Amaral, L. S.; Amarante, A.; Artola, R. A.; Backes, M.; Bath, K. -L.; Bouley, S.; Buie, M. W.; Cacella, P.; Colazo, C. A.; Colque, J. P.; Dauvergne, J. -L.; Dominik, M.; Emilio, M.; Erickson, C.; Evans, R.; Fabrega-Polleri, J.; Garcia-Lambas, D.; Giacchini, B. L.; Hanna, W.; Herald, D.; Hesler, G.; Hinse, T. C.; Jacques, C.; Jehin, E.; Jørgensen, U. G.; Kerr, S.; Kouprianov, V.; Levine, S. E.; Linder, T.; Maley, P. D.; Machado, D. I.; Maquet, L.; Maury, A.; Melia, R.; Meza, E.; Mondon, B.; Moura, T.; Newman, J.; Payet, T.; Pereira, C. L.; Pollock, J.; Poltronieri, R. C.; Quispe-Huaynasi, F.; Reichart, D.; de Santana, T.; Schneiter, E. M.; Sieyra, M. V.; Skottfelt, J.; Soulier, J. F.; Starck, M.; Thierry, P.; Torres, P. J.; Trabuco, L. L.; Unda-Sanzana, E.; Yamashita, T. A. R.; Winter, O. C.; Zapata, A.; Zuluaga, C. A.--This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Context. The Centaur (10199) Chariklo has the first ring system discovered around a small object. It was first observed using stellar occultation in 2013. Stellar occultations allow sizes and shapes to be determined with kilometre accuracy, and provide the characteristics of the occulting object and its vicinity. Aims. Using stellar occultations observed between 2017 and 2020, our aim is to constrain the physical parameters of Chariklo and its rings. We also determine the structure of the rings, and obtain precise astrometrical positions of Chariklo. Methods. We predicted and organised several observational campaigns of stellar occultations by Chariklo. Occultation light curves were measured from the datasets, from which ingress and egress times, and the ring widths and opacity values were obtained. These measurements, combined with results from previous works, allow us to obtain significant constraints on Chariklo's shape and ring structure. Results. We characterise Chariklo's ring system (C1R and C2R), and obtain radii and pole orientations that are consistent with, but more accurate than, results from previous occultations. We confirm the detection of W-shaped structures within C1R and an evident variation in radial width. The observed width ranges between 4.8 and 9.1 km with a mean value of 6.5 km. One dual observation (visible and red) does not reveal any differences in the C1R opacity profiles, indicating a ring particle size larger than a few microns. The C1R ring eccentricity is found to be smaller than 0.022 (3σ), and its width variations may indicate an eccentricity higher than ~0.005. We fit a tri-axial shape to Chariklo's detections over 11 occultations, and determine that Chariklo is consistent with an ellipsoid with semi-axes of 143.8-1.5+1.4, 135.2-2.8+1.4, and 99.1-2.7+5.4 km. Ultimately, we provided seven astrometric positions at a milliarcsecond accuracy level, based on Gaia EDR3, and use it to improve Chariklo's ephemeris. © B. E. Morgado et al. 2021., This work was carried out within the “Lucky Star” umbrella that agglomerates the efforts of the Paris, Granada and Rio teams, which is funded by the European Research Council under the European Community’s H2020 (ERC Grant Agreement No. 669416). This research made use of SORA, a python package for stellar occultations reduction and analysis, developed with the support of ERC Lucky Star and LIneA/Brazil, within the collaboration Rio-Paris-Granada teams. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Part of this research is suported by INCT do e-Universo, Brazil (CNPQ grants 465376/2014-2). Based in part on observations made at the Laboratório Nacional de Astrofísica (LNA), Itajubá-MG, Brazil. The data include observations taken by the MiNDSTEp team at the Danish 1.54 m telescope at ESO’s La Silla observatory” and “UGJ acknowledges funding from the European Union H2020-MSCA-ITN-2019 under grant no. 860470 (CHAMELEON) and from the Novo Nordisk Foundation Interdisciplinary Synergy Programme grant no. NNF19OC0057374. TRAPPIST-South is funded by the Belgian Fund for Scientific Research (Fond National de la Recherche Scientifique, FNRS) under the grant PDR T.0120.21. The authors acknowledge the use of Sonja Itting-Enke’s C14 telescope and the facilities at the Cuno Hoffmeister Memorial Observatory (CHMO). The following authors acknowledge the respective CNPq grants: BEM 150612/2020-6; FB-R 314772/2020-0; RV-M 304544/2017-f5, 401903/2016-8; JIBC 308150/2016-3 and 305917/2019-6; MA 427700/2018-3, 310683/2017-3, 473002/2013-2. G.B.R. acknowledges CAPES-FAPERJ/PAPDRJ grant E26/203.173/2016 and CAPES-PRINT/UNESP grant 88887.571156/2020-00, MA FAPERJ grant E-26/111.488/2013 and ARGJr FAPESP grant 2018/11239-8. J.L.O., P.S.-S., R.D., and N.M. acknowledge financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709), from Spanish project AYA2017-89637-R, and from FEDER. P.S.-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 “LEO-SBNAF” (MCIU/AEI/FEDER, UE). E. Jehin is a Belgian FNRS Senior Research Associate. R.S. and O.C.W. acknowledge FAPESP grant 2016/24561-0 and CNPq grant 305210/2018-1. T.C.H. acknowledges financial support from the National Research Foundation (NRF; No. 2019R1I1A1A01059609).

Recently, the European Commission supported by many European countries has announced large investments towards the commercialization of quantum technology (QT) to address and mitigate some of the biggest challenges facing today's digital era - e.g. secure communication and computing power. For more than two decades the QT community has been working on the development of QTs, which promise landmark breakthroughs leading to commercialization in various areas. The ambitious goals of the QT community and expectations of EU authorities cannot be met solely by individual initiatives of single countries, and therefore, require a combined European effort of large and unprecedented dimensions comparable only to the Galileo or Copernicus programs. Strong international competition calls for a coordinated European effort towards the development of QT in and for space, including research and development of technology in the areas of communication and sensing. Here, we aim at summarizing the state of the art in the development of quantum technologies which have an impact in the field of space applications. Our goal is to outline a complete framework for the design, development, implementation, and exploitation of quantum technology in space., 13 pages, 1 figure

Current Mars entry vehicle technology is near its payload mass delivery limit. Mechanically deployable aero-decelerators are a next generation technology that would enable the future exploration of Mars, including human landing. Various concepts and architectures have been proposed over the years, with widely-varying mass assessments and limited technology development. A novel 6 degree-of-freedom entry trajectory simulator coupled with a structural model of the deployable elements, or ribs, has been developed and correlated against industry tools and flight data to investigate and optimise the design of mechanically deployable aero-decelerators. A major assumption of the simulator – that heatshield gores remain flat under rib deformation – has been investigated by testing ambient 3D woven carbon fabric for use as the flexible thermal protection system material, proving that conditioning can significantly improve the stiffness properties of the fabric. The design optimisation has revealed that, although deployable rib flexibility is beneficial in reducing mass and volume of the deployed ribs, an increase in peak heat flux will result. However, if mass savings from flexible ribs can be reallocated towards increasing the diameter of the entry vehicle, significant entry trajectory benefits can be gained. A set of general design principles for mechanically deployable aero-decelerators has been developed based on the optimisation investigations, including the recommendations to include at least 10 ribs to minimise drag reduction, and to increase the initial rib angle if rib flexibility is allowed to improve deceleration. In addition, the entry vehicle roll rate appears to be influenced by the number of deployable ribs. This roll instability of faceted entry vehicles is of significant concern, so a novel supersonic wind tunnel test methodology was developed to further investigate this hypothesis. The first experimental results imply that pitch and yaw attitude and instabilities are necessary pre-requisites to initiate roll during entry, and that an 8 rib test article rotates at faster rates than the 12 rib test article. Finally, a new functional relationship for the angular acceleration of entry vehicles has been proposed that it is hoped will inspire further investigations in this area. Open Access

Dans cet article, nous identifions plusieurs opportunités et défis ouverts aux systèmes multi-agents, suite aux récents développements dans le domaine des constellations de satellites d'observation de la Terre. Nous nous concentrons sur trois catégories de défis relevant de ce domaine : (i) les problèmes de configuration de constellations et de stations au sol utilisées pour les exploiter, potentiellement opérées par différents acteurs, afin d'améliorer les services fournis et leur coordination ; (ii) les problèmes de planification et d'ordonnancement hors ligne, qui consistent à trouver des méthodes de résolution pour planifier les observations et les tâches de chargement de commandes et de déchargement de prises de vue de la constellation ; et (iii) la conception de méthodes opérationnelles en ligne efficaces et réactives pour adapter les plans dans des contextes dynamiques. Étant naturellement distribués et composés de multiples entités et utilisateurs, ces problèmes s'inscrivent clairement dans le paradigme multi-agent, et peuvent représenter des défis scientifiques et techniques pour les chercheurs en intelligence artificielle distribuée et systèmes multi-agents, pour de nombreuses années.

International audience; In this paper, a novel model-based approach to verify dynamic networks is proposed. The network topology and dynamic link parameters are described as a many sorted first order logic formula, that is verified by an SMT-solver (z3 in our case) with respect to a set of properties. The formula is also used for run-time network verification when a given static network instance is implemented. Preliminary experiments showcase the expressiveness and current limitations of the proposed approach.

International audience; Hyperspectral imaging is a valuable tool for earth observation, with a broad range of applications. Forthe large majority of satellite-based hyperspectral imagers, the 3 dimensional hyperspectral cube is recon-structed from multiple acquisitions of a 2D detector array. Most of these imagers have a 1D field-of-viewso the detector array acquires the spatial data in one direction and the spectral components in the other[1]. The satellite movement is used to acquire the second spatial dimension of the hyperspectral cube. Thismethod of acquisition is straightforward but the light flux received by the detector is low due to the entranceslit defining the field-of-view.

International audience

International audience; The diagnosis procedure in satellite operations is constrained by strict time limits. If a failure occurs, operators must be efficient and proactive, as diagnosis must be completed within the smallest number of visibility windows (pass duration over the ground station which are usually very short and separated by long periods where the ground cannot communicate with the satellite). Improving the diagnosis procedure and tools, time and precision-wise, is therefore essential. The proposal presented in this position paper is to provide the operators with operation-dedicated models to help them in reacting quickly and in finding a suitable repair solution as fast as possible. These models will gather system architecture, functional and dysfunctional data taken from system engineering and safety analysis models. The paper presents the framework of the proposed solution and discusses different implementation options.

International audience; Liver disease is highly prevalent in Africa, especially in the western African country Burkina Faso, due to the presence of multiple biological and chemical aggressors of the liver. Furthermore, diagnosis and appropriate care for liver disease are uneven and usually insufficient. This drives local communities to turn to folk medicine based on medicinal plants from healers. Small scale, ethnopharmacological studies on reputed hepatoprotective plants have been carried out in defined regions worldwide, but so far, no study has been carried out on a countrywide scale. Therefore, we have explored traditional healers’ practices in all thirteen regions of Burkina Faso. We interviewed 575 healers and we compiled a database with 2,006 plant entries. Here, we report results on liver nosology, liver pathologies, medicinal plants used for liver disease, and traditional practices through the lens of Burkinabe healers. Our goal was to give a full inventory of medicinal plants used to treat liver disease and to determine if there was consensus on the use of specific plants for specific symptoms. Analysis of the medicinal plants in use across the whole country provides local communities with a wider evidence base to determine which plants may be more effective in treating liver disease and could provide the scientific community, with a shortlist of plants suitable for chemical and pharmacological investigation to validate the plants’ therapeutic role.

International audience; NB-IoT (Narrowband Internet of Things) has been introduced by 3GPP with the aim of meeting the 5G requirements for the IoT segment through coverage classes, repetitions, narrower subcarriers, user and control planes optimizations and power saving mechanisms. Recognizing the capability of satellite systems to offer wide coverage and enable crosscountries deployment, 3GPP is considering 5G technologies to support Non-Terrestrial Network (NTN). However, while studies have shown the capability of NB-IoT to meet the 5G latency and capacity expectations in terrestrial networks, the question remains open for the satellite context. In this paper, we consider the necessary mechanisms for adapting NB-IoT to the satellite context and provide a study of the delay of a communication as function of gNodeB parameters, cell specification (size, link budget, satellite altitude) and payload size. Our study adopts the configurations used for the simulation based on the link budget given in the 3GPP Study Item and considers not only the random access procedure but also the whole communication process, with signalling, uplink /downlink messages and connection release. We find that the optimal Block Error Rate for minimizing the delay of the communication and optimizing the spectral efficiency is lower that the one recommended in nominal 5G specification.

International audience; Neural networks have become a preferred tool for text classification tasks, demonstrating state of the art performances when trained on a large set of labeled data. However, in an early active learning setup, the scarcity of the ground-truth labels available severely penalizes the generalization capability of the neural network. In order to overcome such limitations, in this paper, we introduce a new learning strategy, which consist of inserting in the early stages of the learning process some additional, local and salient knowledge, presented under the form of simulated, human like rationales. We show how such knowledge can be automatically extracted from documents by analyzing the class activation maps of a convolutional neural network. The experimental results obtained demonstrate that the exploitation of such rationales permits to significantly speed-up the learning process, with a spectacular increase of the accuracy rates, starting from a very reduced number of documents (10–20).

International audience

Context. The electrostatic potential of a spacecraft, VS, is important for the capabilities of in situ plasma measurements. Rosetta has been found to be negatively charged during most of the comet mission and even more so in denser plasmas. Aims. Our goal is to investigate how the negative VS correlates with electron density and temperature and to understand the physics of the observed correlation. Methods. We applied full mission comparative statistics of VS, electron temperature, and electron density to establish VS dependence on cold and warm plasma density and electron temperature. We also used Spacecraft-Plasma Interaction System (SPIS) simulations and an analytical vacuum model to investigate if positively biased elements covering a fraction of the solar array surface can explain the observed correlations. Results. Here, the VS was found to depend more on electron density, particularly with regard to the cold part of the electrons, and less on electron temperature than was expected for the high flux of thermal (cometary) ionospheric electrons. This behaviour was reproduced by an analytical model which is consistent with numerical simulations. Conclusions. Rosetta is negatively driven mainly by positively biased elements on the borders of the front side of the solar panels as these can efficiently collect cold plasma electrons. Biased elements distributed elsewhere on the front side of the panels are less efficient at collecting electrons apart from locally produced electrons (photoelectrons). To avoid significant charging, future spacecraft may minimise the area of exposed bias conductors or use a positive ground power system., Comment: 12 pages, 17 figures, Accepted for publication in A&A

VI Congreso Cuidades Inteligentes, Madrid, ESPAGNE, 15-/09/2020 - 15/09/2020; Le projet PANOPTIS, financé par la Commission européenne dans le cadre du programme H2020, vise à accroître la résilience (capacité d'adaptation) des routes aux conditions météorologiques défavorables, telles que les phénomènes météorologiques extrêmes ou les inondations, et à d'autres événements à risque comme les tremblements de terre ou les glissements de terrain. L'objectif principal du projet est de combiner des scénarios de changement climatique régionalisés (appliqués aux infrastructures), avec des outils de simulation structurels et géotechniques et des données réelles tirées directement des infrastructures routières (ponts, pentes, routes) par un réseau multi-capteurs comprenant des capteurs au sol, des drones et des satellites, afin de fournir aux gestionnaires d'infrastructures de transport un outil de contrôle intégré, capable d'améliorer la gestion des infrastructures dans les phases de planification, de maintenance et d'exploitation. Le projet PANOPTIS a débuté en juin 2018, et pendant la première phase du projet, qui couvre approximativement les deux premières années, toutes les technologies innovantes qui composent l'outil PANOPTIS sont en cours de mise au point. Au cours de la deuxième phase du projet, qui débutera à l'été 2020, ACCIONA Engineering mettra en oeuvre toutes les technologies et méthodologies développées dans la section 2 de l'autoroute A-2, qui est longue de 77,5 km et qui traverse la province de Guadalajara. Il s'agit d'une section de concession d'autoroute de première génération gérée par ACCIONA Concessions et entretenue par ACCIONA Maintenance.

This report proposes a formal introduction to the satellite on-board network requirements. These requirements have been sorted into several categories: Input Contracts which describe constraints on the injection of the messages of the flows in the system (network), Generic Constraints which describe generic constraints as well as medium specific constraints, Quality of Service Constraints which describe constraints on the reception of messages of the flows in the system and Precedence Constraints which describe temporal relationships between flows. One category of constraints have been left behind : Fault Tolerance Constraints, they will not be described in this document.

We propose a novel procedure for outlier detection in space telemetries, in a semi-supervised framework. As the data is functional, we reduce its dimension by considering the coefficients obtained after projecting the observations onto orthonormal bases. A multiple testing procedure based on the two-sample test is defined in order to highlight the levels of the coefficients on which the outliers appear as significantly different from the nominal data. The Local Outlier Factor is computed on the selected coefficients to highlight the outliers. This procedure for selecting the features is applied on simulated data that mimic the behavior of space telemetries and on a real telemetry and then compared with existing dimension reduction techniques.

Scheduling an agile optical Earth Observation satellite (AEOS) requires to choose a limited number of images to take among a large set of possibilities. It is a NP-hard problem which is made even more difficult by the presence of uncertainties: an image is useless if it is too cloudy and weather uncertainty cannot be removed, no matter the accuracy of the forecasts. Moreover, among the various types of customer requests of commercial satellites, we focus here on large area acquisitions that cover a country or a continent. Such requests require several months or years to complete even with a constellation of satellites. Considering such long time frames, the completion time highly depends on weather uncertainties and there are currently no trustworthy forecasts. Therefore the selection of the requests is crucial to speed up the completion using a long-term strategy. Reinforcement Learning is an interesting solution to explore when it comes to uncertain environments. We propose to use the well-known Actor Critic (A2C) algorithm combined with Transfer Learning, Domain Knowledge and Domain Randomization (TDDR). We demonstrate how transfer learning is a way to address real-world problem. We find that TDDR method challenge state-of-the-art heuristics for satellite scheduling on various real weather conditions.

ISBN 978-3-030-58541-9; International audience; In this paper, we investigate the problem of learning disentangled representations. Given a pair of images sharing some attributes, we aim to create a low-dimensional representation which is split into two parts: a shared representation that captures the common information between the images and an exclusive representation that contains the specific information of each image. To address this issue, we propose a model based on mutual information estimation without relying on image reconstruction or image generation. Mutual information maximization is performed to capture the attributes of data in the shared and exclusive representations while we minimize the mutual information between the shared and exclusive representation to enforce representation disentanglement. We show that these representations are useful to perform downstream tasks such as image classification and image retrieval based on the shared or exclusive component. Moreover, classification results show that our model outperforms the state-of-the-art model based on VAE/GAN approaches in representation disentanglement.

This paper proposes a generic approach for crop anomaly detection at the parcel-level based on unsupervised point anomaly detection techniques. The input data is derived from synthetic aperture radar (SAR) and optical images acquired using Sentinel-1 and Sentinel-2 satellites. The proposed strategy consists of four sequential steps: acquisition and preprocessing of optical and SAR images, extraction of optical and SAR indicators, computation of zonal statistics at the parcel-level and point anomaly detection. This paper analyzes different factors that can affect the results of anomaly detection such as the considered features and the anomaly detection algorithm used. The proposed procedure is validated on two crop types in Beauce (France), namely, rapeseed and wheat crops. Two different parcel delineation databases are considered to validate the robustness of the strategy to changes in parcel boundaries.

International audience; The heat transfer performances of capillary-driven evaporators are still improving while their pumping capacity remains drastically limited by the porous wick structure. The pump assistance allows this capillary limit to be overcome and more largely, gives the opportunity of an important enhancement of capillary two-phase loops operating range. An experimental device made of a Capillary Pumped Loop coupled with a controlled centrifugal pump located at the inlet of the evaporator was proposed. We have shown that the hybrid system acts as it would in a simple capillary-driven regime with an operating loop pressure drop far beyond the capillary limit (more than 60 kPa i.e. more than 6 times the evaporator capillary limit with methanol) while preserving the evaporator thermal efficiency due to vaporisation. Moreover, we have found that the pump assistance significantly increases the system robustness during large amplitude heat load step and startup by influencing the liquid subcooling and flow rate at the evaporator inlet.

International audience; This paper aims at comparing satellite-derived and in situ yearly variations of grassland production, over nine farms located in France. During three successive years (2016, 2017, 2018), a dense experimental device has allowed to characterize the variability of grassland production, through a regular survey conducted on more than 169 plots. Ranging from 4.1 to 11.2 t.ha -1 , the yearly production were derived from several tens of thousands of measurements, and combined to derive yearly variations of production. Such unique dataset was compared to a grassland production index, derived from the combined use of medium resolution satellite images and meteorological data. A high level of accuracy is observed between the in situ and the satellite-derived yearly variations of grassland production, with a R 2 of 0.76 and a maximum deviation of 16.3%. Finally, a focus on the maps obtained at the national level makes it possible to analyze the context of the 3 studied years.

International audience; This paper introduces two approaches to automate the design of pipe-systems in a continuous 3D space to assist designers to deal with the high number of constraints of the pipe routing problem. This work assimilates a pipe to a succession of straight sections and bends in which possible bends are restricted to a bend catalog containing orthogonal and non orthogonal bends. As a preliminary work, both methods ignore obstacles but take into account pipe section orientations to deal with asymmetrical pipe sections. To do so, a graph of reachable pipe orientations is generated from the bend catalog. Then, the first approach enumerates valid bend combinations using the previous graph and computes the optimal length of straight sections for each combination using a Linear Program. The second one formulates the pipe routing problem as a Mixed Integer Linear Programming problem based on enumerated reachable orientations. Both approaches are tested on realistic scenarios inspired by industrial problems.

International audience; Pour certaines industries comme l’aéronautique, le spatial ou la construction navale, la conception de réseaux de canalisations joue un rôle important à cause du grand nombre de d’équipements à connecter. En pratique, les ingénieurs conçoivent les routes des canalisations comme une succession de sections droites et de coudes rigides en utilisant leur expérience pour minimiser la longueur et le nombre de coudes utilisés. Afin d’assister les ingénieurs dans cette phase de conception, de nombreux algorithmes de routage automatique de canalisations sont proposés dans la littérature. Cependant, la plupart de ces méthodes ne considère que des coudes orthogonaux, réduisant ainsi la qualité des solutions obtenues. De plus, l’orientation de la section de canalisation n’est généralement pas prise en compte, ce qui est pourtant impératif dans le cas de canalisations de section rectangulaire. Dans ce travail, on propose deux approches de routage automatique dans un environnement sans obstacle pour des canalisations à section rectangulaire utilisant les coudes (potentiellement non orthogonaux) d’un catalogue.

Full understanding of this paper requires expertise in computer science, software engineering and algorithmics.; The intelligent routing of application flows between, on the one hand, a fleet consisting of many equipments (fixed or mobile) equipped with a heavy client-side software or a light browser providing a service to end-users, and, on the other hand, a park of servers equipped with a server-side software contributing to this service, is a complex problem. A fleet may include, for example, users' computers accessing an e-commerce site, smartphones, payment terminals, ATMs and banking services, internet boxes, shopping terminals tickets, kiosks access public service, etc. The complexity of routing is inherent in the many constraints that this function should address. First, it must be adaptable to any client-side and server-side software via a single function point that interacts at the session and kinematic level. It must also take into account the compatibility matrix of the multiple deployed versions of the software. Second, it must be adaptable to any platform via a setting of topological rules incorporating the specifics of the software in the existing architecture, and allow a logical multi-criteria segmentation of the fleet and the park via a setting of rules of affinity and exclusion between any groups of equipments and servers (domains, markets, versions, service levels, etc.). Third, it must support an unlimited fleet with horizontal scaling capacity, and must dynamically enslave the load and load transfer with consideration of the overconsumption of resources generated by the software during rerouting, in order especially to avoid the cascaded spread of massive incidents (domino effect). Fourth, when necessary, it must be able to sacrifice certain flows, temporarily, to preserve a greater number of flows. Finally, the routing must offer a real-time vision of the state of the fleet and the park, and allow the automatic enrollment in the fleet of new discovered equipments. Because existing ADC (Application Delivery Controller) solutions insufficiently meet the requirements, this paper proposes a heuristic algorithm integrated into a reverse proxy, responding to the needs. This heuristic is presented in the context of automated banking machines, but can easily be transposed to any other context. Because the complexity of the problem does not allow to calculate routes in a reasonable time, the proposed heuristic does not seek the best mathematical solution but an effective and reactive routing that imitates social behaviour and maximizes availability, usability, quality of service. This inventive heuristic was implemented and tested successfully, jointly with a second invention playing the role of a distributed database (“A distributed, probabilistic, hysteretic, retroactive algorithm to locally weaken the CAP/Brewer’s theorem when reading data on a distributed computer system” ⟨hal-01966396⟩ https://hal.archives-ouvertes.fr/hal-01966396). Full understanding of this paper requires expertise in computer science, software engineering and algorithmics.

For the past decades, networks have evolved to increase their performances, their capacities, to reduce latencies and optimize their resource management in order to remain competitive and adapted to the market. Today, the way consumers use networks has changed and more heterogeneous services with their own requirements have emerged. This has led network operators to define the network slicing paradigm. Network slicing creates multiple partitions in the network, each partition can be dedicated to a particular service allowing vertical markets and multiple services with different requirements to run on top of a single infrastructure. To allow the flexibility level required by network slicing, satellite technologies have to evolve. Satcoms actors have therefore been working on improving satellite equipments. Testbeds followed the theoretical analysis and ESA's current project SATis5 is making it its core topic. The work presented in the full-paper of this extend abstract is the next step we propose to those initiatives. It focuses on the network slicing concept applied to satellite networks which, we believe, is a mandatory requirement for a full integrated satellite into 5G networks. We first start by describing the main challenges associated to the satellite slice definition. We then highlight a set of requirements for such a satellite slice. Based on those requirements, we construct and propose a complete Satellite Slice as a Service (S3) framework which mutualizes the satellite infrastructure to provide a seamless integration into 5G networks., 2 pages, 1 figure

International audience; The aim of this paper is to present a high precision and event-versatile MBPTA framework that we have developed for the statistical timing analysis of multicore platforms. Its use satisfactorily allows the study of complex multicore platforms from the CPU point of view, without requiring hardware or software models. This gives us an accurate real view of the platform behavior for any specific situation without using extra tools. In addition, this measurement framework is directly portable to other multicore platforms with the same CPU version and easily portable to other CPU versions within the same manufacturer.The MBPTA framework directly uses coprocessors and the Performance Monitor Unit (PMU), i.e. Performance Monitor Hardware (PMH), instead of software profilers. Hardware performance counters provide low-overhead access to a considerable amount of performance information of numerous elements such as the CPU, caches or bus.The statistical timing analysis consists in proposing average and worst-case modeling by making use of the tool diagXtrm applied to measurement of task execution times.Measurements obtained from the PMH are used for analyzing and quantifying the interference that can happen within a multicore platform.The potential for measurements from coprocessor and PMU, as well as its potential for statistical analysis, is shown by using an heterogeneous multicore Texas Instrument system on chip. The interference we focus on are due to the shared memory of this platform.

International audience; L’intelligence artificielle comprend une diversité de sous-domaines au nombre desquels figure l’UEBA (User and Entity Behaviour Analytics). Ce dernier, en plein essor, repose sur l’analyse automatique des comportements humains et non humains. Plus spécifiquement, dans le domaine de la cyber-sécurité, un procédé UEBA consiste à détecter des actions hostiles en se basant sur la nature inhabituelle des événements observés sur un système d'information.Les systèmes défensifs de type UEBA existant à ce jour souffrent de certaines limitations que nous cherchons à contourner. À cette fin, nous avons conçu un système de type UEBA associant, d’une part, des réseaux de neurones profonds auto-encodeurs permettant la détection d'anomalies comportementales individuelles, avec d’autre part, un procédé permettant de corréler une pluralité d’événements organisés en graphes afin de détecter les scénarios hostiles constituant une attaque notamment de type APT (Advanced Persistent Threat).Déjà, notre système réduit le taux de faux positifs et négatifs, il produit des alertes fortement explicables et possède une capacité de mise à l’échelle horizontale. Cependant, nous n'avons pas encore adressé la problématique dite de la « dérive conceptuelle », laquelle se manifeste par une obsolescence progressive du modèle appris des comportements, inhérente à l'évolution temporelle naturelle des comportements du système observé.Pour contourner cette dérive, il est nécessaire d’entrainer en continu un système de détection basé sur les anomalies, ce qui ouvre la porte à un adversaire susceptible de mener une attaque dite de la « grenouille ébouillantée », laquelle consiste pour l’attaquant à distiller progressivement les traces d’une attaque afin que ces dernières demeures inaperçues et soient in fine intégrées au modèle des comportements normaux, rendant ainsi l’attaque indétectable.Nous présentons ici un aperçu de notre solution capable d’affaiblir efficacement une telle attaque en améliorant le processus de détection et en tirant parti de l'expertise humaine. Nous présentons également des travaux préliminaires sur une intelligence artificielle adversaire menant une attaque par leurrage, qui sera utilisée pour aider à évaluer et à améliorer le système de défense. Ces systèmes défensif et offensif mettent en œuvre un apprentissage joint, continu et actif, dans une étape qui est nécessaire à l'évaluation, à la validation et à la certification des solutions défensives basées sur l'intelligence artificielle de type UEBA ou autre.

International audience; Aircraft equipment health monitoring system plays a promising role for airlines operation cost reduction, as it can be exploited to perform predictive maintenance. In this vein, a hierarchical sequential decision making model is proposed to plan predictive maintenance. It combines linear optimization for routing assignment and MDP planning to handle maintenance actions based on the stochastic evolution of health indicators. This entangled model should reduce planning time while ensuring a cost-efficient policy.

In March 2020 the United Nations published an open brief for the creative community to propose interventions to the unfolding COVID-19 pandemic. However, when faced with unprecedented wicked problems such as these, the rigour of design and creative processes can tested. COVID-19 has demonstrated how important human centred design responses are in understanding the worldviews and ecosystems of users. Ad hoc design responses or design hacks have demonstrated that they have a role to play in how we create our future individual, community and societal ecosystems. In terms of age friendly design, this pandemic makes us envision what should be, furthermore, how we could create better products and services through technology. For our ageing communities ‘Cocooning’ and other social restriction measures have exposed technological deficiencies for the needs of older people and opens up questions of our future preparedness for a growing ageing society. Now more than ever, designers need to understand the behavioural mind-set of older people in their own ecosystem and understand existing mental models. In this opinion piece we posit what acts of design hacking can lead us to greater understanding of users mental models and therefore better understanding of technology needs for both older and younger adults. While presenting various examples of how design hacking is conducted by citizens and participants alike, it shows that it offers designers differing perspectives, experiences and inspiration for technology.

With the advent of an increasing number of high-throughput telecommunication satellite constellations in Low Earth Orbit (LEO), tracking performance requirements for User Terminals (UTs) have become more stringent. A way to efficiently perform the Acquisition (ACQ) and Tracking (TRK) of a fast-moving LEO satellite along its trajectory is needed. Phased Array Antennas (PAA) are particularly suited for this type of application since their radiation patterns can be rapidly changed and their main lobe quickly steered without any need of mechanical components. In particular, Active PAAs, possessing an individual transceiver module per each array element, can extract the information of all individual array elements. This information can later be processed by algorithms to get the Directions of Arrival (DOAs) of the satellite signals arriving at the array. Namely, subspace-based DOA estimation methods are commonly implemented in systems employing Active PAAs, since they make full use of the detailed array information available. The aim of this work is to determine which subspace-based DOA estimation algorithms for UTs based on Active PAA technology work best for ACQ and TRK scenarios involving LEO satellite constellations. An extensive bibliographic study of array data modelling, subspace-based DOA estimation methods, and subspace tracking algorithms was carried out. The most promising methods were implemented in MATLAB. Furthermore, a full ACQ plus TRK simulation system was coded and used to test application scenarios with real satellite constellation data to conclude which algorithms yielded the best real-time performance. From the results of several worst-case scenario simulations, it was concluded that satellite DOA estimations were the most accurate when using the Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) method for both ACQ and TRK alongside the Fast Data Projection Method (FDPM) algorithm for updating the spatial covariance matrix each time step. Further remarks and future research directions are discussed as well.

International audience; The problem of estimating a tight and safe Worst-Case Execution Time (WCET), needed for certification in safety-critical environment, is a challenging problem for modern embedded systems. A possible solution proposed in past years is to exploit statistical tools to obtain a probability distribution of the WCET. These probabilistic real-time analyses for WCET are, however, subject to errors, even when all the applicability hypotheses are satisfied and verified. This is caused by the uncertainties of the probabilistic-WCET distribution estimator. This article aims at improving the measurement-based probabilistic timing analysis approach providing some techniques to analyze and deal with such uncertainties. The so-called region of acceptance model based on state-of-the-art statistical test procedures is defined over the distribution space parameters. From this model, a set of strategies is derived and discussed to provide the methodology to deal with the trade-off safety/tightness of the WCET estimation. These techniques are then tested over real datasets, including industrial safety-critical applications, to show the increased value of using the proposed approach in probabilistic WCET analyses.

International audience; In this paper, a two-dimensional integral boundary layer method developed in a recent work is applied to ice accretion computations. The method has already been validated in terms of boundary layer dynamic effects in another article. It is here validated for its ability to capture ice shapes, once the method is included in an icing suite. To be more specific, results using the new boundary layer method are compared against experimental ice shapes and simulated ones with the widely-used simplified integral method. The validation is carried out at an aggregated level because icing databases generally provide access to final ice shapes only. But since the simplified integral method is used in many icing numerical tools, this comparison makes it possible to investigate the benefits of introducing the new method for calculating the boundary layer. The main outcome of the new method is an improvement of the prediction of the boundary layer prediction under smooth-wall assumption, which in turn improves ice shape prediction. It is shown that, overall, the ice shapes are indeed either better predicted with the new method than with the baseline approach, or equally predicted with both methods. In addition, since the heat transfer coefficient tends to be underestimated by simplified integral methods, the new approach tends to predict lower horn angles than the baseline approach. Finally, the consequences of these results on current and future developments of ice accretion solvers are discussed. In particular, the new method is better suited to a 3D extension than the simplified integral method.

In this paper, a comparison of quantum efficiency and dark current densities of shallow etched and deep etched InAs/GaSb type-II superlattice photodiodes is presented. The detectors were tailored for space applications with measured cut-off wavelengths around 11.2 µm. Bias and temperature dependencies of the QE have been studied showing very low turn on bias (>−25 mV) and very small variation of the peak QE value with temperature. At 70 K, peak quantum efficiencies of shallow and deep etched devices were deduced to 34% and 30%, respectively (without antireflection coating). The difference was attributed to a larger collection area of shallow etched devices, with a collection range of approximately 22 µm outside of the defined pixel area. Diffusion limited dark currents were observed down to 60 K for both shallow and deep etched devices under low reverse bias (∼−200 mV) with dark current densities on the order of 1.7 × 10−5 A/cm2 at 60 K. A gradually increasing influence of generation-recombination (G-R) and trap-assisted tunneling (TAT) was observed at lower temperatures for high reverse bias. The lowest dark current densities were observed for deep etched photodiodes, on the order of 3 × 10−7 A/cm2 at 40 K (Vbias = −100 mV). Detector arrays were fabricated with deep etched 30 µm pitch pixels. Comparably low dark current densities were observed for the detector array pixels under low reverse bias as for the single pixel photodiodes, however a significant increase of the TAT dark current was observed under high reverse bias.

The research work presented in this paper focuses on the development of a mixed active-passive microvibration mitigation solution capable of attenuating the transmitted vibrations generated by reaction wheels to a satellite structure. A representative benchmark provided by the European Space Agency (ESA) and Airbus Defence and Space, serves as a support for testing the proposed solution. The paper also covers modeling and design issues as well as a deep analysis of the solution within the H ∞ / μ setting. Especially, an uncertainty modeling strategy is proposed to extract a Linear Fractional Transformation (LFT) model. Insight is naturally provided into various dynamical interactions between the plant elements such as bearing and isolator flexibility, gyroscopic effects, actuator dynamics and feedback-loop delays. The design of the mitigation solution is formulated into the H ∞ / μ framework leading to a robust H ∞ control strategy capable of achieving exemplary active attenuation performance across a wide range of reaction wheel speeds. A systematic analysis procedure based on the structured singular value μ is used to assess and demonstrate the robust stability and robust performance of the microvibration mitigation strategy. The proposed analysis method is also shown to be a powerful and reliable solution to identify worst-case scenarios without relying on traditional Monte Carlo campaigns. Time domain simulations based on a nonlinear high-fidelity industrial simulator are included as a validation step.

This work is dedicated to Philippe Augros.32 pages, 41 ref.; International audience; In this work, we develop a new method to design energy minimum low-thrust missions (L2-minimization). In the Circular Restricted Three Body Problem, the knowledge of invariant manifolds helps us initialize an indirect method solving a transfer mission between periodic Lyapunov orbits. Indeed, using the PMP, the optimal control problem is solved using Newton-like algorithms finding the zero of a shooting function. To compute a Lyapunov to Lyapunov mission, we first compute an admissible trajectory using a heteroclinic orbit between the two periodic orbits. It is then used to initialize a multiple shooting method in order to release the constraint. We finally optimize the terminal points on the periodic orbits. Moreover, we use continuation methods on position and on thrust, in order to gain robustness. A more general Halo to Halo mission, with different energies, is computed in the last section without heteroclinic orbits but using invariant manifolds to initialize shooting methods with a similar approach.

International audience; Forward Error correcting Code design (FEC) and implementation for optical feeder link is reported. The designed LDPC codes present very good performances (BER < 1e-9) while requiring less than 20% hardware resources of FPGA compatible with space constraints. Protection scheme based on these LDPC codes combined with a physical layer bit interleaver is presented. Links sizing for GEO optical feeder link at 30° elevation angle under strong turbulence shows that uplink might require up to 100W per link.

International audience; Optical Earth observation satellites acquire images worldwide , covering up to several million square kilometers every day. The complexity of scheduling acquisitions for such systems increases exponentially when considering the interoperabil-ity of several satellite constellations together with the uncertainties from weather forecasts. In order to deliver valid images to customers as fast as possible, it is crucial to acquire cloud-free images. Depending on weather forecasts, up to 50% of images acquired by operational satellites can be trashed due to excessive cloud covers, showing there is room for improvement. We propose an acquisition scheduling approach based on Deep Reinforcement Learning and experiment on a simplified environment. We find that it challenges classical methods relying on human-expert heuristic.

A simulation strategy combining an octree-AMR and an HRL turbulence model with overset grids is investigated in FLUSEPA™, the Finite-Volume solver developed by ArianeGroup. The turbulence model used is a \(k- \varepsilon \) with a Delayed Detached Eddy Simulation [14] treatment for the destruction term of k. First, we study the influence of the refinement criteria on the pressure fluctuations in the recirculation area of a cylindrical backward facing step. Using an initially coarse grid, we compare the results with those from a fixed fine grid calculation. Then, the methodology is applied to the numerical simulation of the buffeting of an Ariane 5 model.

The surface of Europa is geologically young and shows signs of current activity. Studying it from a photometric point of view gives us insight on its physical state. We used a collection of 57 images from Voyager's Imaging Science System and New Horizons' LOng Range Reconnaissance Imager for which we corrected the geometric metadata and projected every pixel to compute photometric information (reflectance and geometry of observation). We studied 20 areas scattered across the surface of Europa and estimated their photometric behavior using the Hapke radiative transfer model and a Bayesian framework in order to estimate their microphysical state. We have found that most of them were consistent with the bright backscattering behavior of Europa, already observed at a global scale, indicating the presence of grains maturated by space weathering. However, we have identified very bright areas showing a narrow forward scattering possibly indicating the presence of fresh deposits that could be attributed to recent cryovolcanism or jets. Overall, we showed that the photometry of Europa's surface is more diverse than previously thought and so is its microphysical state., Comment: 46 pages, 17 figures, 3 tables

International audience; Multi-Processor System-on-Chips (MPSoCs) is a standard platform used in time-critical applications. These platforms usually employ Priority-Preemptive NoCs (PP-NoCs), a widely used real-time on-chip interconnection structure that offers communication predictability. A deep analysis of the PP-NoC parameters and their impact on system security is required. Moreover, countermeasures that can protect the system while guaranteeing the real-time capabilities should be proposed and evaluated. To this end, this paper explores and evaluates the impact of the PP-NoCs parameters on system security; exploits PP-NoCs vulnerabilities and demonstrates for the first time two very powerful attacks; and proposes and integrates three new security countermeasures: RT-blinding, RT-masking, and RT-shielding. Results show that PP-NoCs are vulnerable to attacks and that is possible to uncover victim’s information with high accuracy (up to 96.19%). On the other hand, protection techniques were able to harden the system, effectively and efficiently mitigating the vulnerabilities while maintaining deterministic behavior.

International audience

NanoCarb is an innovative Fourier-transform imaging spectrometer dedicated to the measurement of CO2and CH4. Both its unusual optical principle and sampling strategy allow to reach a compact design, ideal for small satellite constellation as investigated by the European project SCARBO. The NanoCarb performance assessment as well as a proof of concept is required in this framework. We have developed a design strategy to optimize the performances. We demonstrate the potential of the concept through an estimation of the sensitivity, compliant with the space mission target. We also present a preliminary mitigation of the bias induced by water on CO2and CH4retrieval, illustrating the efficiency and the flexibility of the NanoCarb partial interferogram sampling technique. The presented design reaches a sub-ppm random error for CO2and sub-10 ppb random error for CH4, considering 128 km swath and 2 by 2 km2ground resolution. Design optimization and more systematic performances are discussed.

International audience; Space system undergo particularly hard natural radiation environment, but can also potentially be subject to the radiations injected in low earth orbit by the explosion of a nuclear weapons. The increasing use of optoelectronic components in space systems makes the risk assessment regarding the radiation effects of an increasing interest. This paper presents recent results about the degradation of optoelectronic devices in term of atomic displacements. This paper Most of this work has been developed under the EDA contract JIP-ICET2 A-1341-RT-GP within the CapTech Technologies for Components and Modules’ (TCM) in EDA.

International audience; This paper presents a research study on control strategies for satellite’s Electrical Power System. SPACE Grid, which is a collaboration between the CNES, Airbus Defence and Space and the LAPLACE laboratory, consists in the modelling and determination of power management strategies on a new electrical architecture based on distributed Power Conditioning and Distribution Units. Are presented the models developed and the primary control implemented, inspired from ground-based DC micro-grids techniques. Future improvements and high-level control are also discussed at the end of the paper.

International audience; The system‐centered informal representation of a local reality is originally built intentionally by a “sentient being” who is aware that a real situation requires a certain wholeness. The work is based on a pragmatic body of interdisciplinary knowledge constitutive of a system‐centered architecting specification, in harmony with human‐centered and technical‐centered multidisciplinary knowledge. It is necessary to inquire about its outwards materiality as an integrative foundation of multidisciplinary systems engineering, respectively technical and human‐centered. Formalizing the physico‐physiological interaction under investigation combines certain elements of multidisciplinary knowledge of integrative physiology. The chapter describes what enables the tangibility of the togetherness of the sensory perception interaction between an “artifact‐source” of an alarm and a “human‐sink” of control, as a necessary condition. The model of human‐centered intelligent measurement is orchestrated in silico in a first step by the system architect throughout the co‐simulation bus for partial system validation.

International audience; In this paper, we describe the NanoCarb concept as well as its key elements. Then we will explain the design of the prototype followed by the development of characterization techniques. Finally, we will present how this tool can be used as part of end-to-end model. The key element of the NanoCarb concept is a matrix of silicon Fabry-Perot micro-interferometers, which allows us to perform both imaging and interferometry with a field of view of 18° and several interferometric samples in a snapshot. This technique permits us to optimize the SNR for a much reduced volume. The very complex and unusual design of this component brings huge optical and technological challenges, and requires the development of characterization techniques at the nanometer scale. Upon achievement of this purpose, the next step will be the integration of this matrix in a NanoCarb prototype to demonstrate its effective performances. We present a test bench using the interferential metrology technique of Optical Coherence Tomography (OCT). In a first time, we managed to obtain optical path maps of different silicon wafers with nanometer accuracy. Then, we employed the technique to characterize the first micro-interferometers. In parallel, we realized the first prototype integration of NanoCarb with an InGaAs focal plane array and started its characterization

International audience