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International audience; Au droplets are used as a catalyst for the growth of nanowires on Si(111) substrate via the vapor-liquid-solid (VLS) mechanism. The dewetting of a Au thin film is the most common method to obtain these droplets. The control of this step is crucial to adjust the density and the diameter of the nanowires during VLS growth. When the Si(111) substrate is covered with a silicon dioxide layer, the kinetics of Au droplet formation is strongly modified. The dependence of the diameter and spatial distribution of the droplets on the surface have been studied by scanning electron microscopy with respect to the thickness of the silicon dioxide layer, the thickness of the Au film and the temperature of the substrate during deposition and post-deposition annealing. In-situ low energy electron microscopy and low energy electron diffraction revealed the dynamics of the Au droplet formation after annealing. The Au droplets are shown to catalyze the decomposition of silicon dioxide at high temperature (> 650-700 °C) and form a wetting layer of Au-(33)-Si(111). Consequently, the droplets absorb silicon atoms from the substrate, migrate perpendicular to the atomic steps and grow by the Smoluchowski ripening process.

International audience; Our research team was included in an industrial project to design autonomous shuttles. For the first stages of the project, an escort was in the shuttle for legal reasons and to “ensure safety”: he can take control of the shuttle at any time. The prescription addressed to this escort was to intervene as little as possible. We analyzed the real activity and lived experiences of the escorts on four sites of experimentation of the shuttle in different European cities by different types of observations and interviews. Results show that respecting the prescription lead to a transport service with very little traffic. Most escorts have gradually adopted behaviors to improve the utility of the shuttle service, scarifying security value. Designing from a “total security” perspective can lead to useless services and prohibited behaviors. We argue that “acceptable security” model is ultimately more secure in the real world.

International audience; Automated systems and robotics have been presented for several years as a major stake in the development of companies because they are supposed to increase productivity on the one hand, and improve the health of operators on the other hand, for example by automating difficult tasks. However, as human remains essential to productive systems, the effective collaboration of man and technology depends largely on the acceptability of these new technologies by operators. The assessment of acceptabilité in the design phase of a new technology is therefore an major scientific issue to assess early the costs and benefits perceived by future users.Despite the attention paid to the acceptability of operators, we note that many investment projects related to new technologies encounter difficulties of integration in the socio-professional context of the company, even though Acceptability is good or very good. The purpose of our research is to understand this contradiction and our postulate is as follows: the acceptability assessments are carried out outside the context of use, which does not allow the operators to evaluate concretely the contributions and the limits of the technology.To understand the dimensions of acceptability that can be fairly easily evaluated in an experimental context and those that pose problems we have integrated an experiment around the use of a new robot, during a picking task. The robot automatically follows the operator and carries the packages he has deposited on robot.This experiment took place in 3 stages:- First phase: learning the task of order picking with a manual trolley through the realization of 10 orders;- Second phase: learning how to operate the robot by performing 1 command;- Third phase: realization of 10 commands with the robot, with 7 commands that incorporated into the environment obstacles hindering the operation of the robot.The evaluation of acceptability was carried out following these 3 phases using the UTAUT 2 questionnaire (Venkatesh, Thong and Xu, 2012). To give participants the opportunity to express their inability to answer a question, we changed the value scale by replacing the "neutral" box in the middle with "do not know how to answer"Overall, the results show that the use of the robot leads to an evolution, mostly positive and less frequently negative, of the participants' acceptability, which reinforces the idea of the need to put in a situation of use the operator to better appreciate its future acceptance of the technology.Nevertheless, we also note that some important dimensions of acceptance (Bobillier-Chaumon, 2016) are difficult to assess through our experimentation, particularly the relational and identity dimensions, where people have more frequently meant that they were not able to answer.These results may confirm the interest of experiments in measuring a number of variables, but also the need to associate experimental conditions with conditions and / or methods which can integrate or simulate more satisfactorily relational and identity dimensions of human experience. We consider these as a major factors in the processes of acceptance of new technologies. By replacing the indication "do not know how to answer" with a "neutral" score (e.g. average score), as expected in UTAUT 2, these dimensions are “diluted” in the overall acceptability assessment that seems very good.

[Departement_IRSTEA]Ecotechnologies [ADD1_IRSTEA]Équiper l'agriculture; International audience; This paper presents the results of an analysis of the activities during manual and robotised piece picking tasks to know and understand the impact of the robotisation. Here, this task is manually realized first and then partially automated with a robot. The activity is described with three indicators. These indicators are computed with image processing and a subdivision of the picking area. The robot has an impact on the activity because its introduction induces a convergence of the subjects to the same activity regardless without of their uses of technologies considering the interaction in this case

International audience; Dans le cadre d’un projet industriel de conception de navettes de transport autonomes (sans chauffeur), notre recherche analyse les expériences vécues et les valeurs en acte des accompagnants afin d’identifier leur contribution à l’acceptation des navettes et du service associé, et de poursuivre la conception de ce service de transport. En effet, à l’étape du développement actuel du projet, le système de transport n’atteint pas le niveau d’autonomie visé et un accompagnant est systématiquement présent à bord de chaque navette. En 2015 et 2016, des investigations ont été menées sur quatre sites sur lesquels les navettes étaient mises à l’essai. Ont alors été réalisés : des analyses systématiques des situations critiques gérées par les accompagnants, et des entretiens composites (semi-directifs inspirés des techniques d’explicitation) auprès de 19 accompagnants. Les résultats montrent que les accompagnants mobilisent 7 valeurs dans leur activité. Quatorze situations critiques impliquant des arbitrages dans des situations où ces valeurs se révèlent contradictoires ont été identifiées. Les réponses apportées en situations révèlent que la hiérarchisation de ces valeurs dépend d’arbitrages variables et situés. Nous discutons ensuite de la contribution de ces réponses à l’acceptation du système de transport, notamment en fiabilisant sa performance, en maximisant son utilité et en développant une relation de service auprès des passagers. Ces résultats conduisent ainsi à interroger le statut de l’humain dans les processus de conception et d’acceptation de technologies autonomes et des services associés

International audience; Dans le cadre d’un projet industriel de conception de navettes de transport autonomes (sans chauffeur), notre recherche analyse les expériences vécues et les valeurs en acte des accompagnants afin d’identifier leur contribution à l’acceptation des navettes et du service associé, et de poursuivre la conception de ce service de transport. En effet, à l’étape du développement actuel du projet, le système de transport n’atteint pas le niveau d’autonomie visé et un accompagnant est systématiquement présent à bord de chaque navette. En 2015 et 2016, des investigations ont été menées sur quatre sites sur lesquels les navettes étaient mises à l’essai. Ont alors été réalisés : des analyses systématiques des situations critiques gérées par les accompagnants, et des entretiens composites (semi-directifs inspirés des techniques d’explicitation) auprès de 19 accompagnants. Les résultats montrent que les accompagnants mobilisent 7 valeurs dans leur activité. Quatorze situations critiques impliquant des arbitrages dans des situations où ces valeurs se révèlent contradictoires ont été identifiées. Les réponses apportées en situations révèlent que la hiérarchisation de ces valeurs dépend d’arbitrages variables et situés. Nous discutons ensuite de la contribution de ces réponses à l’acceptation du système de transport, notamment en fiabilisant sa performance, en maximisant son utilité et en développant une relation de service auprès des passagers. Ces résultats conduisent ainsi à interroger le statut de l’humain dans les processus de conception et d’acceptation de technologies autonomes et des services associés

International audience; In networks that operate during a long time, the routing protocol might have to be changed: this is the case when the network administrator plans a router change. Loop-free transition algorithms are used to ensure that there is no loop during the migration from the initial routing protocol to the final routing protocol. In this paper, we propose a distributed loop-free transition algorithm, called DLF (distributed loop-free heuristic). The algorithm is based on the fact that routing loops resulting from the removal of a node are localized, and can be detected efficiently. We show through simulations that DLF compares well with the existing centralized algorithms, and outperforms the existing distributed algorithm, in terms of migration duration.

International audience; Le développement de la robotique, des technologies intelligentes, et respectueuses de l'environnement, est un enjeu sociétal en évolution croissante ces dernières années. Le cas particulier de la mobilité innovante est porteur d'enjeux forts pour le développement de nos entreprises, de nos usages, voire de notre santé. Ainsi, dans le cadre d'un projet de recherche pluri-disciplinaire (ingénierie, psychologie, ergonomie) incluant des industriels de la conception automobile, nous avons pu contribuer à la conception d'une navette autonome (sans chauffeur). A la lumière de modèles de l'expérience utilisateur, nous avons analysé l'activité des usagers, mais également celle des autres individus gravitant autour de la navette. Nos premiers résultats ont permis à la fois d'alimenter nos partenaires concepteurs en spécifications fonctionnelles (accessibilité, sécurité, confort, utilisabilité…), mais également de réinterroger les modèles utilisés, et d'entrevoir de nouvelles problématiques de recherche pour appréhender notamment les liens entre les dimensions de l'expérience utilisateur et de l'acceptabilité des innovations, leur hiérarchisation éventuelle, la question de l'utilité de ce moyen de transport et de la prise en compte des besoins réels des utilisateurs potentiels.

International audience

In this paper two optimum models to study the transport of passengers and goods through the VIPA (Automatic individual Public Vehicle) are proposed. The objective is to minimize the number of times the vehicles stop. Since those are autonomous vehicles (they have no driver), the operations of deceleration, acceleration, stopping, opening and closing doors and going out of the circuit to go to the station implies a loss of reliability. Therefore, minimizing the number of times the vehicles stop is crucial to ensure their fleet works efficiently. Moreover, doing this we will achieve less energy expense, the minimization of the total time and the maximization of the number of served clients.

A manuscript on this topic can be found at: http://hal.archives-ouvertes.fr/hal-00908242; International audience; In a carsharing system, a fleet of cars is distributed at stations in an urban area, customers can take and return cars at any time and station, provided that there is a car available at the start station and a free place at the final station. To ensure the latter, customers have to book their demands in advance; hereby, customer requests can be accepted or rejected by the operator. The stations have to keep a good ratio between available cars and free places in each station, in order to serve already accepted customer requests and to refuse as few new customer requests as possible. This leads to the problem of relocating cars between stations, which can be modeled as Pickup and Delivery Problem in a metric space induced by the urban area or, alternatively, by means of flows of cars in convoys in a time-expanded network.Note that we consider an innovative carsharing system with partly autonomous cars which allows to build convoys of cars, each moved by only one driver. This leads to a similar situation as in bikesharing systems, where trucks can simultaneously move several bikes, but no requests are booked in advance. Hereby, two flows are coupled in the sense that the flow of cars is dependent from the flow of drivers (since cars can only be moved in convoys); the flow coupling constraints reflect the complexity of the studied problem.We present integer programming formulations for two variants of the relocation problem: a min-cost flow problem to serve a given set of customer requests at minimal costs (quality of service aspect), and a max-profit flow problem to additionally solve the decision problem of accepting or rejecting customer requests (economic aspect). Both models take advantage of users booking their demands in advance and can be applied to the offline as well as the online version of the relocation problem in order to fully capture the dynamic evolution of the system over time.

This work aims at reconstructing Petri net models for biological systems from experimental time-series data. The reconstructed models shall reproduce the experimentally observed dynamic behavior in a simulation. For that, we consider Petri nets with priority relations among the transitions and control-arcs, to obtain additional activation rules for transitions to control the dynamic behavior. An integrative reconstruction method, taking both priority relations and control-arcs into account, was proposed by Favre and Wagler in 2013. Here, we detail the aspect of choosing priorities and control-arcs such that dynamic conflicts can be resolved to finally arrive at the experimentally observed behavior.

Version 1 - Présentation à ISCO 2014; We deal here with a static decisional model related to the monitoring of a DARP (Dial and Ride) model which involves, on a closed industrial site, small electrical autonomous vehicles. Because of technological issues, we focus on reliability, and propose a model which assign requests to vehicles while minimizing Load/Unload transactions. We study this model through both a Branch/Price approach, which provides us with benchmarks, and insertion based heuristics, well-fitted to dynamic contexts.

International audience; Smart camera networks (SCN) raise challenging issues in many fields of research, including vision processing, communication protocols, distributed algorithms or power management. Furthermore, application logic in SCN is not centralized but spread among network nodes meaning that each node must have to process images to extract significant features, and aggregate data to understand the surrounding environment. In this context, smart camera have first embedded general purpose processor (GPP) for image processing. Since image resolution increases, GPPs have reached their limit to maintain real-time processing constraint. More recently, FPGA-based platforms have been studied for their massive parallelism capabilities. This paper present our new FPGA-based smart camera platform supporting cooperation between nodes and run-time updatable image processing. The architecture is based on a full reconfigurable pipeline driven by a softcore.

International audience; Smart camera networks raise challenging issues in many fields of research, including vision processing, communication protocols, distributed algorithms or power management. The ever increasing resolution of image sensors entails huge amounts of data, far exceeding the bandwidth of current networks and thus forcing smart camera nodes to process raw data into useful information. Consequently, on-board processing has become a key issue for the expansion of such networked systems. In this context, FPGA-based platforms, supporting massive, fine grain data parallelism, offer large opportunities. Besides, the concept of a middleware, providing services for networking, data transfer, dynamic loading or hardware abstraction, has emerged as a means of harnessing the hardware and software complexity of smart camera nodes. In this paper, we prospect the development of a new kind of smart cameras, wherein FPGAs provide high performance processing and general purpose processors support middleware services. In this approach, FPGA devices can be reconfigured at run-time through the network both from explicit user request and transparent middleware decision. An embedded real-time operating system is in charge of the communication layer, and thus can autonomously decide to use a part of the FPGA as an available processing resource. The classical programmability issue, a significant obstacle when dealing with FPGAs, is addressed by resorting to a domain specific high-level programming language (CAPH) for describing operations to be implemented on FPGAs.

International audience; —The main challenges in smart camera networks come from the limited capacity of network communications. Indeed, wireless protocols such as the IEEE 802.15.4 protocol target low data rate, low power consumption and low cost wireless networking in order to fit the requirements of sensor networks. Since nodes more and more often integrate image sensors, network bandwidth has become a strong limiting factor in application deployment. This means that data must be processed at the node level before being sent on the network. In this context, FPGA-based platforms, supporting massive data parallelism, offer large opportunities for on-board processing. We present in this paper our FPGA-based smart camera platform, called DreamCam, which is able to autonomously exchange processed information on an Ethernet network.

International audience; We deal here with a multi-machine scheduling problem with non idling constraints, i.e constraints which forbids the interruption of the use of the processors. We reformulate the problem, while using specific pyramidal profile functions, next get a min-max feasibility criterion and finally derive exact polynomial algorithms for both the feasibility problem and the makespan optimization problem.

This work aims at reconstructing Petri net models for biological systems from experimental time-series data X'. The reconstructed models shall reproduce the experimentally observed dynamic behavior in a simulation. For that, we consider Petri nets with priority relations among the transitions and control-arcs, to obtain additional activation rules for transitions to control the dynamic behavior. The contribution of this paper is to present an integrative reconstruction method, taking both concepts, priority relations and control-arcs, into account. Our approach is based on previous works for special cases and shows how these known steps have to be modified and combined to generate the desired integrative models, called X'-deterministic extended Petri nets.