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International audience; In order to face the continuous increase of the data traffic on cellular networks, using WiFi to offload the LTE network can be an interesting solution for the operators. The convergence between fixed and mobile access allows the WiFi access points to be connected to the cellular eNodeBs. This is known as very tight coupling between LTE and WiFi. WiFi and LTE flows are merged just bellow the IP layer which allows faster attachment procedures to WiFi access points and dual WiFi/LTE transmission while providing a seamless experience to the end user. However, WiFi networks are very different from LTE in terms of delays and loss rates which may have a bad impact on higher layers such as TCP. In this paper, we study the performance of TCP with Very Tight Coupling. We perform experimentation on a real testbed based on the Open Air Interface framework.

International audience; Noncooperative underwater acoustic (UWA) communication systems are prone to interfere with each other since the limited resource offered by the channel is not regulated by any standard. Mutual inteferences can significantly degrade the performances of such systems and it is necessary to find policies allowing UWA devices to access the same physical resource. In this paper, we consider noncooperative UWA OFDM systems competing to access the same portion of the spectrum. We show that an efficient decentralized power allocation strategy can be achieved when all the communication links apply a waterfilling policy only based on little knowledge about their environment. Numerical simulations performed with real UWA channels sounded at-sea demonstrate the relevance of our approach.

International audience; Configurable process models are gaining a great importance for the design and development of reusable business processes. As these processes tend to be very complex, their configuration becomes a difficult task. Therefore, many approaches propose to build decision support systems to assist users selecting desirable configuration choices. Nevertheless, these systems are to a large extent manually created by domain experts, which is a time-consuming and tedious task. In addition, relying solely on the expert knowledge is not only error-prone, but also challengeable. In this paper, we propose to learn from past experience in process configuration in order to automatically extract a configuration guidance model. Instead of starting from scratch, a configuration guidance model assists analysts creating business-driven support systems.

International audience; In this paper we present the concept of context-aware Emergency Notification and Rescue Service (ENRS) utilizing user information from the 4G EPC network. The 4G EPC is an all IP next generation architecture that makes it easy for various 3GPP and non-3GPP standards to co-exist and provide network access to the end user. The proposed architecture consists of two parts; first part is emergency notification and information gathering to use for the event notification. The second part consists of an intelligent context-aware decision engine that processes the collected information in real time and generates notification messages for the end user. Our proposed service is based on the RESTful concepts and can be used to effectively notify and help users during the emergency. Currently a prototype of the service is being developed to validate the ENRS.

Aircraft performances at landing or takeoff depend strongly on runway surface conditions. There is a need to provide aircraft pilots with reliable information in view of determining landing performance. Currently, these information are based on a description of the type and the depth of contaminants on the runway surface. This paper presents a new method to improve the correlation between friction coefficients and braking coefficients measured respectively by ground vehicles and aircrafts. A three steps approach is proposed, using a friction model developed by ESDU, to weight the measured coefficients by factors taking into account the characteristics of the devices and of the contaminants. The friction ESDU model is used on contaminated surfaces. The methodology is applied to data collected from extensive friction tests conducted between 1996 and 2003 (Joint Winter Runaway Friction Measurement Program). Characteristics of ground friction measuring devices and aircrafts are provided as inputs for ESDU model. It was found that the correlation between weighted ground friction and braking coefficients is improved significantly compared with the correlation between unweighted coefficients. Advantages of the newly proposed method are discussed in terms of using ground friction coefficients as a promising alternative to determine Runway condition code for aircraft pilots.

International audience; In the context of future seabed underwater scientific observatories, a new Wi-Fi antenna (at 2.45 GHz) was recently developed for high data rate and short range wireless underwater applications. It supports real time video and rapid large file transmissions (54 Mb/s during experiments). Also its simplicity and compatibility with standard Wi-Fi equipment (modems, etc.) makes it a low cost solution for underwater applications. Therefore, while first prototypes have ever experimentally demonstrated the capabilities of the developed solution, several optimizations are possible. This paper focuses on size reduction and improvement to sea pressure resistance, bandwidth broadening, and a new antenna excitation which notably enable further height reduction.

Cet article a pour objectifs : • de présenter un ensemble de bonnes pratiques qui peuvent être inspirées de l'application de la norme internationale ISO 10006 (2003) : « Systêmes de management de la qualité - Lignes directrices pour le management de la qualité dans les projets », dans l'organisation et la réalisation d'une recherche universitaire, débouchant sur une matrice de 54 éléments, • d'illustrer au travers de huit bonnes pratiques la maniêre de mettre en application sur le terrain une telle approche, • de positionner ces concepts dans la stratégie qualité globale de l'institution universitaire concernée, • de suggérer l'élaboration de 3 nouvelles normes internationales en relation avec les démarches qualité en recherche., The objectives of this article are: - to present a set of good practices which can be inspired by the application of the international standard ISO 10006 (2003): "Quality management systems - Guidelines for quality management in projects", in the organization and carrying out university research, leading to a matrix of 54 elements, - to illustrate through eight good practices the way to apply such an approach in the field, - to position these concepts in the overall quality strategy of the university institution concerned, to suggest the development of 3 new international standards in relation to quality approaches in research.

National audience; Real-time adaptive production control in the flexible manufacturing cell (FMC) is a complex issue that needs to be addressed to realize good performance and high productivity. In this paper, we have considered a support vector machine (SVM)-based simulation approach to resolve a production control problem in an FMC that operates in a dynamic environment. A SVM-based simulation approach chooses the most relevant scheduling rule out of several predefined ones on the basis of the current states of the system. This paper examines and compares the performance of the SVM-based simulation approach with the competent scheduling rules under two different operational environments which are characterized by the uncertainty of demand. We have also developed a Visual Basic-based simulation approach for scheduling of component parts in the context of FMC under different situations. The SVM methodology to control the production offers better performance than the single-rule-based production control system.

International audience; For some companies, visual inspection has become an essential step when seeking to improve the quality of their products. The aim of this control is to be sure of the perceived quality of the product, which often goes well beyond the quality expected by the customer. For this type of control, the controller should be able to detect any anomaly on a product, characterize this anomaly, and then evaluate it in order to decide if the product should be accepted or rejected. This paper describes how this characterization can be carried out and, more specifically, how to measure the impact of the local environment of an anomaly on the perceived quality of the product.

Constructed wetland systems for wastewater treatment have been proven to be effective, low cost and sustainable alternative for wastewater treatment technologies. This paper is about the Austrian experience in constructed wetland systems.

This paper is an attempt to describe a building design as a hypertext genre. It represents a single– or multi-volume document that has to be submitted when applying for a planning permission issued by an appropriate administrative authority, usu. by Building Surveyors. Its broad thematic scope provides the best proof of its multidisciplinary character – indeed, it bears witness to the complexity of investment process which has to result eventually in the completion of a new building. Building designs consist of texts featuring various genres that belong to different discourse types – apart from administrative ones, they involve texts dealing with architecture, urban architecture, structural engineering, interior fit-outs, electrical and heating facilities, sanitary fittings. Law regulations precise the exact content of a building design, which heavily depends on the putative function of a building, its degree of complexity and environmental setting. A building design thus turns out to be a multilayered genre whose composition is related to extra linguistic factors (design location and its function). It exhibits features typical of hypertext genres: non-sequentiality (non-linearity), component independence of hyperstructure, polyphony (many authors), primacy of global coherence and interactivity. All the characteristics make it difficult to apply traditional models of describing linear texts to building designs, thus proving that the dividing line between text and hypertext genres is independent of the media boundary.

National audience; Multi-touch interaction requires a trade-off between users' desires and capabilities, and gesture recognition constraints. Current approaches to that problem lack flexibility. The number of fingers used for a gesture usually plays a key part in the recognition process, for example. In this paper, we propose the use of pseudo-rigid movements to increase the flexibility of this process. We show how these movements can be determined in real time from the contact information usually available. We explain how they allow to free the recognition process from the number of fingers used and to move towards multi movement gestures, independent or coordinated. Finally, we present an interaction technique that takes advantage of this increased flexibility.

This paper describes an experiment conducted on a mockup of a Personal Information Space. Users were asked to perform data entry and retrieval tasks, then to modify the mockup according to their needs and wishes. The results allowed to validate the item structure for the future personal space, and to assess the role of user modifications as evaluation cues, and for the development of further ergonomic recommendations.

International audience; Multiple-Input/Multiple-Output (MIMO) techniques have recently become an important research field for enhancing the performance of in-home Power Line Communication (PLC) systems by exploiting the additional Protective Earth wire. The development of such systems requires an accurate description of the channel noise. In this paper we have presented a model for PLC background noise based on an extensive set of measurements. We have adopted the framework of multivariate time series to model the PLC background noise.This paper employs the Vector Autoregressive (VAR) modeling technique to extract noise model parameters from the measured noise. We have verified the accuracy of the noise model by comparing time and frequency domain correlation of measured and modeled noises.

In this paper, a study of an autonomous hybrid PV-Wind-battery system for a residential house of 4 persons in La Rochelle in France is presented. It includes system design optimization and performance evaluation in addition of its economic and environmental life cycle analysis. The results show a low environmental impact and a reasonable economic cost of the system.

This paper deals with an issue that has rarely been addressed for the Neolithic period : the degree of functional specialization of ceramic productions. The question was applied to the earliest pottery from Bulgaria (6100-5500 BC). Results obtained on the pottery function from Kovačevo suggested in fact that some vessels were manufactured for a specific use. From the ceramic assemblage of this site, a new analytical method was developed to assess the degree of functional specialization. This method involves comparing the variability of pottery from a same functional range with those of the whole ceramic assemblage. The attributes that distinguish them could thus be identified. Next, their impact on the properties required by the different use of vessels (resistance to thermal and mechanical shock, waterproofing or heating efficiency) was measured using experimental and ethnographic data. However, some characteristics significantly change the performance of vessels. It was thus deduced that a part of the ceramic production from the site was already devoted to a particular purpose during the manufacturing process. At Kovačevo, two categories of ceramic vessels were undoubtedly produced for a specific function : storage vessels and cooking pots. Indeed, these two categories show a whole range of specific features which were particularly suited for their actual use. Thus, storage vessels often present a very thick slip on their inner surfaces which has not been identified in other functional classes of pottery. However, this type of slip gave them the high waterproofing required for storing substances. Cooking pots always have a narrow opening and a flat base. Their walls are relatively thick and their outer surfaces are often slip trailed. The combination of these different attributes provided them with the excellent thermal shock resistance required for cooking. Other functional classes of ceramic vessels were not necessarily made for the use to which they were put. This is the case of pottery used for grinding products. Indeed, they do not seem very suitable for this specific function. The study carried out on the ceramic assemblage from Kovačevo has allowed different degrees of functional specialization to be identified within the same pottery range : loww and high. These different degrees of specialization may be explained by more or less important use constraints depending on the function of the ceramic vessels. The preliminary work carried out the functional specialization of ceramic productions has finally provided a new picture about the first Neolithic potters from Bulgaria. The choices made during the manufacturing process of storage and cooking vessels confirm that their know-how was high. Indeed, these potters knew the technical solutions required to meet the different use constraints of ceramic vessels. Moreover, the choices made to optimize the pottery efficiency show that not only environmental, technical and cultural factors determined the potters’ behaviour. The function of ceramic vessels could also influence it., Vieugué Julien. Spécialisation fonctionnelle des premières productions céramiques dans les Balkans (6100-5500 av. J.-C.) . In: Bulletin de la Société préhistorique française, tome 109, n°2, 2012. pp. 251-265.

Because of the industrial progress in Britain during the eighteenth century, many visitors came to see what was being achieved. Thus began a long tradition of industrial espionage and technology transfer. Some came simply out of interest and curiosity, but the main aim was to rival Britain in industry and production. This paper provides examples of these activities. à cause du progrès industriel en Grande Bretagne pendant le dix-huitième siècle, il y arrivait beaucoup de visiteurs pour observer les réussites britanniques. C’est ainsi qu’a commencé une longue tradition d’espionnage industriel et transfert de techniques. Pour quelques-uns, la raison était tout simplement l’intérêt et la curiosité mais, pour la plupart, leur but était de rivaliser la Grande Bretagne en industrie et production. Dans cette communication, on trouvera des exemples de ces activités.

A characterization of the different patterns of technological development of France and Britain in the late eighteenth and early nineteenth century which has been frequently put forward considers French engineers and scientists involved in the formulation and discovery of theoretical and general principles, whereas their British counterparts were mainly working using “rules of thumbs” and other similar forms of empirical know-how. At least, prima facie, the case of steam engineering seems to fit this broad characterization rather well. In this paper we provide a reconsideration of the different nature of French and British practices in steam engineering. Our study shows, that the different economic circumstances prevailing in Britain and France (in particular the price of coal) led the two countries to embark to different paths of accumulation of “useful knowledge” in the field of steam engineering. La caractérisation des modèles de développement technologique en Grande-Bretagne et en France à la fin du XVIIIe siècle et au début du XIXe siècle repose largement sur l’idée que les ingénieurs et savants français se sont impliqués dans la découverte et la formulation de principes théoriques et généraux, alors que ceux anglais utilisaient des astuces et autres formes de savoir-faire empirique. Du moins, à première vue, le cas de la vapeur semble épouser assez bien cette distinction. Dans cet article, nous proposons de reconsidérer la nature des pratiques françaises et anglaises dans les techniques de la vapeur. Notre étude montre que les circonstances économiques différentes existant en Grande-Bretagne et en France (en particulier le prix du charbon) ont conduit les deux pays à choisir des voies différentes d’« accumulation du savoir » dans le domaine des techniques de la vapeur.

International audience; In this paper, the authors describe a modeling and design method for a permanent magnet drive used in a power train for Hybrid Electric Heavy Vehicle, based on a Series-Parallel architecture. The hybrid powertrain structure enables high requirements for boost mode of acceleration and full electric mode. A 'Ravigneaux' train was integrated in this hybrid powertrain structure in order to split energy among the vehicle wheels, the thermal engine, the electrical motor and the alternator. To compare the classical simple epicyclic train used in series-parallel Toyota hybrid structure, this 'Ravigneaux' train developed by Nexter group presents a better adaptation to high mechanical constraints (high power and torque) because of its double stages compound structure. Several operation modes of vehicle were analyzed by assuming that the two electrical machines were identical and reversible (they can both operate as a motor or an alternator). In this paper, a simple drive is considered: it deals with a Surface-Mounted Permanent Magnet Synchronous Machine (SMPMSM) and a two level Voltage Source Inverter (VSI). An analytical modeling based on three working points: boost working point, nominal working point and maximal rotation speed working point has been elaborated. The analytical modeling makes it possible to model the physical behavior of different components. It enables to analyze quickly the relationship between the different parameters. A numerical modeling using 2D finite elements is also presented in this paper. The aim of 2D finite elements analysis (2DFEA) is to validate the machine performances obtained by analytical modeling. It enables to model some physical phenomena with a better accuracy, such as magnetic saturation. Generally, the results given by 2DFEA will be closer to experimental results. The control law of the electrical machine was investigated by the way of a single-phased electromechanical modeling. With this model, the flux weakening analysis has been taken into account in order to adapt the motor winding according to the rotation speeds defined in the specifications. The flux weakening was realized by considering mechanical and electrical characteristics linked with power, torque, rotation speed, DC-link voltage, feeding voltage of electrical machine, Id and Iq currents, cyclic inductance, winding resistance, back-electromotive force, phase difference between back electromotive force and phase current... The electrical machine losses have been calculated by neglecting the mechanical losses and PM losses. The machine losses calculation includes the copper losses and the iron losses (eddy currents losses and hysteresis losses). The flux density in the stator yoke and the teeth was evaluated by taking into account the magnetic flux created by permanent magnet and the one created by armature reaction (stator current). The inverter losses were calculated too, by considering the commutation and conduction losses of both diodes and IGBT transistors. Thus, the total losses and the global efficiencies of motor and inverter were evaluated and the best working points can be deduced from those calculations. The previous models enable to evaluate global energy performances of electrical machines and inverters by respecting the constraints defined in the specifications. This methodology is general and can be a first step of a complete power train optimal design, including the electrical drive, the gear, the energy storage units and possibly the internal combustion engine.

Fatigue strength is of prior concern for automotive chassis parts design. In a reliability framework, its assessment still requires long and expensive test campaigns. In particular, high-cycle endurance tests usually involve several specimens undergoing million-cycle procedures. In order to reduce the specimen number (e.g. expensive prototypes) and to shorten testing procedures (i.e. time-to-result delay), Accelerated Life Tests (AFT) are developed under the constraint of the needed high-reliability assessment. These methods do not involve high frequency load cycling, but are mainly based on stress magnification and fatigue damage equivalence. In this paper, at first a review of the fatigue test procedures currently used in the automotive industry (e.g. StrairCase, Locati and StairCase-Locati) is addressed. Thus, numerical simulations are used in order to assess the efficiency of these test procedures and compare their performances.

A multi scale methodology is proposed for the study of the cellular material behavior under dynamic loading. The behavior of polymeric foams studied depends on the constitutive material and the morphology of the porous structure. The cellular material of this study is constituted of millimetric porous beads, these beads are themselves constituted of microscopic closed cells. The methodology proposed to model the multi scale morphology of the structure (the scales of beads and cells) of the cellular material; it consists in implementing simple mechanical models at the different scales to reproduce the complex physical phenomenon observed and to model the macroscopic response of the foam. The observation and the analysis of physical phenomenon is the first step of the multi scale modeling. This paper describes the experimental and numerical methods used to observe and describe the structure of the cellular material, and quantify deformations and damages of these structures at the scales of beads and cells. Two ways of modeling were investigated: a finite-element model to represent the bead structure and another approach, more original, by the use of a modified discrete element model to model the microscopic structure of the cells.

International audience; The paper presents parametric analysis of durability factors of RC highway bridges strengthened with CFRP laminates during their service life. Durability factors considered are concrete cover and CFRP laminate thickness. Three deterioration factors were considered. First, growth of live load with time. Second, resistance reduction due to chloride-attack corrosion which causes reduction in steel properties. Corrosion losses are evaluated through a time–temperature dependent corrosion current. Two types of corrosion are considered; uniform and pitting corrosion. Third, deterioration due to aging of CFRP. The reliability analysis is controlled by three failure modes; concrete crushing, CFRP mid span debonding and CFRP rupture. Monte-Carlo simulation is used to develop time dependent statistical models for rebar steel area and live load extreme effect. Reliability is estimated in term of reliability index using FORM algorithm. For illustrative purpose, a RC bridge is assumed as an example. The reliability of interior beam of the bridge is evaluated under various traffic volumes and different corrosion environments. The bridge design options follow AASHTO-LRFD specifications. The present work also extends to calibrate CFRP resistance safety factor corresponds to three target reliability levels, β=3.5, 3.85, and 4.2. The results of the analysis have shown that corrosion has the most significant effect on bridge life time followed by live load growth. Pitting corrosion type is more hazardous than uniform. Also, initial safety index is proved to be traffic dependent. AASHTO design equation (that corresponds βtarget=3.5) seems to be overestimated for strengthening purpose. Strengthening with (βtarget=4.2) provide better reliability than βtarget proposed by AASHTO provision with no significant differences in CFRP amounts required.

LGEP 2011 ID = 876; International audience; In order to find better solution for the development of Electric Vehicles (EVs), many research are performed by companies, universities and research laboratories. The main goal of these works is to provide some solutions to reduce the cost, increase the compactness, improve the autonomy and the reliability as well as the vehicle energetic efficiency and last but not least, reduce the global carbon emissions impact of the vehicle. This paper deals with an on-board battery charger for EVs or PHEVs where power electronics are reduced thanks to the use of same power converters in traction and charger mode. RST controllers in discrete time are design to control the PWM rectifier for the single-phase case.

National audience; In Human-Computer Interaction, plasticity refers to the capacity of User Interfaces (UI) to adapt to the context of use (user, platform, environment) while preserving user-centered properties. Until now, plasticity was the scope of various studies. The adaptation from a context of use to another was studied in order to satisfy the end-user's requirements. This paper changes the focus: plasticity in itself is not the scope anymore; it is viewed as a way for designers to improve UI quality. The iterative design process is detailed for a case study where all design decisions have been recorded in terms of their influence on UI ergonomic quality. The case study deals with e-goverrment procedures. The return of experience shows that paying attention to plasticity for a small screen platform results in improvements on the large screen platform version due to the reexamination of its initial design; En Interaction Homme-Machine, la plasticité désigne la capacité des Interfaces Homme-Machine (IHM) à s'adapter aux variations du contexte d'usage (utilisateur, plate-forme, environnement) en conservant la qualité attendue par l'utilisateur. La plasticité a fait l'objet de nombreuses études ; l'adaptation d'un contexte d'usage à un autre y était envisagée dans le but de satisfaire l'utilisateur final. Dans cet article, la perspective est différente : la plasticité n'est plus l'objet de l'étude mais un moyen pour le concepteur d'améliorer la qualité des IHM. L'étude de cas présentée dans cet article est la conception d'une téléprocédure citoyenne plastique. Nous relatons tous les choix de conception et étudions leur impact sur la qualité des IHM. En particulier, nous montrons que concevoir une IHM pour un petit écran permet d'améliorer la qualité d'une version grand écran conçue au préalable.

International audience; Cognitive assistance systems are aimed to support people loosing their autonomy while completing activities of daily living (ADL). The range of activities to support, the dissemination of interactive devices in the environment and the variability of users' cognitive capacities raise real challenges when designing assistance in such systems. This paper addresses the assistance issues and presents guidelines for assistive systems design. Especially, based on an experiment of the assistance provided while completing ADL, we suggest a principle of scaled assistance. The principle was applied to Archipel, a cognitive orthesis. This application and the results analysis of a 12 sujects experiment led to the evaluation and the improvement of some ergonomic guidelines about ambient assisted living

The Partial Element Equivalent Circuit method (PEEC) is well suited to the extraction of the conducted electromagnetic (EM) disturbance parameters in the electronic wiring systems. It can be an efficient tool for the EMC study relevant to automotive cables. However, the complete EMC analysis of embedded systems requires also reliable models for the radiated emissions especially at high frequencies. In this paper, an efficient approach based on the PEEC method is developed for the modeling of the cable radiations.

The constantly increasing market request of high quality vehicles ask the automotive manufacturers to perform lifetime testing in order to verify the reliability levels of new products. In this paper, we deal with two difficulties in reliability assessment for mechanical parts. On one hand, there is the small number of parts available for testing. On the other hand, there is the problem of wear. In the automotive applications, mechanical components subjected to relative motion of parts have to be designed against wear. In this paper, the Bayesian estimation of Wiener process parameters (usually used to define the degradation process) is studied to improve the estimation accuracy in incorporating the available knowledge on the product. In particular, the finite element results and expert knowledge are considered as “a priori”. For wear prediction by FEM, a model based on Archard law was developed for the brake disc wear.

The conversion efficiency of three way catalytic converters is mainly defined by the temperature range wherein they are operating. Traditionally, ignition retard has been used to reduce the light-off time of the catalyst. This is however associated with a fuel penalty. With increasing vehicle electrification, electrically heating facilities present an alternative, especially for hybrid vehicles. Nevertheless, system complexity of hybrid vehicles prevents engineers to evaluate possible heating technologies and their corresponding fuel penalty with respect to traditional solutions. This paper evaluates the application of an electrically heated catalyst on a hybrid vehicle equipped with a Natural Gas (NG) engine. The effect of heating power on light-off time and fuel penalty is determined, using analysis techniques emerging from integrated powertrain control. By means of a case study, the importance of an integral approach is explained by comparing the fuel penalty and conversion efficiency improvement of electric heating with that of ignition retard. In this process, a mix of simulation and test data were combined, forming the foundations for future control developments of a suitable light-off strategy. © 2010 Institut français du pétrole.

International audience; Due to operational constraints for underwater data acquisition, simulating realistic sonar data, like images, swath bathymetry profiles or interferometric signals, is crucial for tuning detection and classification algorithms according to sensors settings, sea-bottom nature and topography. Moreover, the robustness of any performance estimation or prediction can be greatly enhanced, as soon as such a simulation tool provides a modular and flexible underwater world representation (multiple sensors, environments and acquisition conditions). For signal and array processing, it is essential not only to generate the signal energy backscattered by a resolution cell, but also to produce a phase information that conveys its theoretical statistical properties. To this end, this paper proposes a Brownian motion-based approach to generate complex Gaussian signals from the contribution of a set of extended single scatterers inside a resolution cell. The resulting process preserves the conservation of energy when integrating on surfaces, as well as the decorrelation between different areas of the sea bottom, and the right interference between two sensors for interferometric applications.

National audience; The development of micro and nanotechnologies requires the design of microrobots and Microsystems able to handle submillimetric objects. Many micromanipulation systems have been built. However, improvement of the performances requires the use of advanced control methods. In this paper, we present the main characteristics of the microworld from a control point of view and some control strategies adapted to the microsystems.

International audience; Basé sur la théorie du contrôle par supervision (TCS), nous proposons une démarche d'aide à l'étude de la dynamique des Systèmes à Événements Discrets (SED). Située en amont du cycle de conception des lois de commande des SED, notre proposition concerne la gestion des modes de fonctionnement. L'objectif est de permettre tout d'abord l'étude formelle de la dynamique du système contrôlé dans chaque mode puis celle de la succession de ces dynamiques. Dans cet article nous insisterons particulièrement sur la présentation des différentes étapes de construction et de génération automatique des modèles ainsi que sur les possibilités de validation de ceux-ci. Based on the Supervisory Control Theory, this paper introduces a framework to help study the dynamics of Discrete Event Systems (DES). Upstream of the design process of control law in DES, the proposal focuses on the management modes of operation. The goal is to first allowing a formal study of the controlled system's dynamics in each mode and secondly studying the mode switching. This article is focused on the presentation of the different stages of design, the automatic generation of models and the possibilities of validating them.

This paper describes the design and the placement of piezoelectric actuators on switched reluctance motors by means of a genetic algorithm (nondominated sorting genetic algorithm II) for the purpose of reducing stator vibrations. Two distinct approaches are presented: one energy-related and the other based on a minimization of the resultant displacement. These methods lead to design and placement strategy for the piezoelectric actuators. A number of optimal actuators obtained using these kinds of approaches is also compared with mechanical finite-element simulations. At last, a solution is achieved in order to validate optimal placement using positive position feedback active filtering.

This paper presents an original design option dedicated to output-filtered pulsewidth modulation inverters used in uninterruptible power systems, embedded networks, or motor drives operating on long cables. It is based on the coupling of interleaved inverter cells by means of intercell transformers (ICTs) and is characterized by very good dynamic behavior on load transients, which is an important issue in such applications. ICT solutions are compared with the classical interleaved solutions using separate inductors. A specific design method is developed to achieve this comparison based on toroidal core shapes. The results obtained with a 600 V, 7.5 kW inverter show the usefulness of ICT-based designs, especially when nanocrystalline magnetic material is used; high specific power and very good dynamic performances are obtained.

National audience; This paper presents a steering assistance system that prevents unintended lane departures. The assistance intervenes only when the driver is inattentive and the vehicle is about to leave the lane. Road curvatures represent a challenge for the control law concerning the lane keeping performance as well as the lane overshoot in the case of activation in curves. To address these issues, the control law has been designed by using invariant sets theory and bilinear matrix inequalities optimization methods. Field tests have shown the theoretical expectations to be fulfilled and have demonstrated the high robustness properties of the implemented control law.

This paper deals with new architectures for power electronics converters. These architectures are based on interleaved elementary power conversion cells interconnected and coupled using intercell transformers. The advantages of such architectures are demonstrated through three kinds of applications.

International audience; The main goal of Fault Tolerant Control Systems (FTCS) is to preserve the ability of the system to achieve the objectives that has been assigned when faults or failures occurred. The main goal of this work is to develop a fault tolerant control strategy that incorporates both reliability and dynamic performance of the system for control reconfiguration. Once a fault has been detected and isolated, the reconfiguration strategy proposed in this paper tries to find possible structures of the faulty system that preserve prespecified performance, calculate the system reliability, compute new controller gains and finally search the optimal structure that has the "best" control performance with the highest reliability. The proposed approach is illustrated through a hydraulic and thermal system of three tanks.

This paper deals with the monolithic integration around vertical power devices. It presents the work carried out toward the integration of the gate driver within the power device, thanks to a N-MOS technology. It is based on modeling and analysis of correct functional operation of the lateral N-MOS devices thanks static curves. These devices are integrated within the power device thanks to a full share of technological steps between the two types of devices. Thanks to the analysis, a full gate driver is designed and integrated. At the end of the paper, the work is partially validated thanks to experimental results.

International audience; Dans la première partie de ce travail, on se propose de comparer le comportement rhéologique de bétons identifié à l'aide de différents rhéomètres, en utilisant une méthode de traitement des données permettant le tracé direct de la courbe d'écoulement du matériau. Dans une deuxième partie, les propriétés rhéologiques de bétons industriels sont étudiées au moyen d'un rhéomètre de forte capacité de couple muni d'une géométrie à ailettes. Les résultats permettent d'évaluer et de comparer les propriétés d'écoulement des bétons et de juger de la reproductibilité du procédé de fabrication. In the first section of this paper, the rheological behaviour of concretes obtained with different rheometers is investigated from a procedure allowing the plot of the flow curve of sheared material. Secondly, the rheological properties of industrial concretes are studied with a high torque vane rheometer. The flow properties of concrete are evaluated and compared, as well as the reproductibility of the making process of concrete.

In this paper we propose a control scheme based on Coloured Petri net (CPN) for a flow-rack automated storage and retrieval system. The AS/RS is modelled using Coloured Petri net. The developed model is used to capture and provide the rack state. We introduce in the control system an optimization module as decision process which performs a real-time optimization working on discrete events time scale. The objective is to find bin locations for the retrieval requests by minimizing the total number of retrieval cycles for a batch of requests and thereby increase the system throughput. By solving the optimization model, the proposed method gives according to customers request and the rack state, the best bin locations for retrieval, i.e. allowing at the same time to satisfy the customers request and carrying out the minimum of retrieval cycles.

This paper introduces a new modeling method suitable for the simulation of shell fracture under impact. This method relies on an entirely meshless approach based on the smoothed particle hydrodynamics (SPH) method. The paper also presents the SPH shell formulation being used as well as the different test cases used for its validation. A plasticity model of the global type throughout the thickness is also proposed and validated. Finally, in order to illustrate the capabilities of the method, fracture simulations using a simplified fracture criterion are presented.

An analysis of an arched ball bearing that considers centrifugal forces and gyroscopic effects is performed. Based on operating conditions of a 5 DOF inner ring and Coulomb friction model, the conventional bearing theory is extended from 2 to 3 and 4 contacts. The commonly used control criterion of a ball bearing by the inner or outer raceway is debatable and is known to fit experimental data with difficulty, and when more than two contact points are involved it becomes obsolete. The paper presents a mathematical model to describe the ball internal kinematics under the effect of the operating conditions. This analysis makes it clear that the total power loss varies strongly with the one or two added sources of friction. The maximum PV factor is also affected by the full sliding of the lightly loaded contacts induced by the arched design.

When investigating the electrical characteristics of granular assemblies under dynamical solicitations (powder, steel bead assemblies, etc.), it is difficult to distinguish between effects that are purely electrical and those that are strongly dependent on mechanical effects. Although numerous experimental works have permitted better understanding of the static electrical behaviour of such media, it is difficult to determine the effects control the multi-physical behaviour of the medium, especially under dynamical solicitations. In the present paper, numerical investigations of the electrical characteristics of granular material are proposed. Moreover, it presents the formulation of a new model, embedded in the general scheme of discrete element methods, that couples electrical and mechanical effects and takes into account the oxidation phenomenon. Numerical simulations on the basis of experimental works are performed to validate the model, and the results of dynamical simulations are discussed. Copyright © 2007 John Wiley & Sons, Ltd.

This paper deals with face gear design. The goal is to propose a simple formula for predicting the width of the wheel as a function of the main design parameters. A specific software was used to achieve this goal. This numerical tool is able to simulate the geometry and the quasistatic loaded behavior of a face gear. The statistical method used for analyzing the influence of data is described: The design of experiments leads to a simple regression model taking into account the influential parameters and their couplings. In the last part of this paper, the results of the formulas are compared to those of the software and an optimal design is proposed based on the regression model.

cote interne IRCAM: Noisternig08a; None / None; National audience; Auralization is the process of making audible the acoustics of complex virtual architectural spaces in a realistic and accurate manner. This paper presents a novel real-time auralization software environment comprising a room acoustic modeler, a spatial renderer for auralization, and a visualization and scene graph unit for interactivity. The computation of early reflection paths within the geometric model is based on an efficient beam tracing algorithm capable of real-time detection of specular reflection paths in a static geometry with one or several moving listener(s). For “simple" rooms, the real-time performance is maintained even with dynamic geometries and sources. Results of the room acoustic model consisting of visible reflection paths and their accumulated material attenuation are sent to the audio renderer. From this geometrical and acoustical data, listener position-relative 3D room impulse responses are generated using a hierarchical-order Ambisonics approach. Finally, the spatialized audio output is presented to the listener via multiple loudspeakers or binaurally rendered over headphones. As higher order reflections are more diffuse in nature, they are encoded using lower Ambisonic orders, thereby reducing computational load. The environment combines high quality audio with visual rendering realized using the open source platforms Pure Data and VirChor respectively. This open source auralization framework provides direct audio-visual interaction in real-time and is suitable for VR environments.

Nowadays, the wheels of worm gears with a low module can be made of plastic, thus classical modeling can no longer be used satisfactorily. The present paper describes an original method for studying the quasi-static loaded behavior of a worm gear, with a steel worm and a nylon wheel. A generalized Kelvin model is proposed and the computation of load sharing is described by using an equation of displacement compatibility. The history of previous deformation and the effect of the nylon’s structural damping are also taken into account. Experimental measurements of the Loaded Transmission Error are performed with the help of optical encoders rigidly connected to the worm and gear shafts, giving access to their instantaneous angular positions. The numerical simulations fit quite well with the experimental results.Copyright © 2007 by ASME

The paper proposes a comprehensive model to predict the skew movement of a roller in tapered roller bearings. Numerical solutions are given on a LM48548/LM48510 bearing. The effect of the shaft speed, ring misalignment, and lubricant temperature on the roller skew angle is presented and compared to the experimental data available in the literature. The results indicate that the skew angle depends first on the misalignment angle between the cup and the cone. The roller skew is also greatly influenced by the traction at the roller-flange contact, the skew angle increasing with the traction at this contact, and by the geometry of the roller end.

This paper deals with systematically applying a modern principle of designing real-time simulators, namely the HILS (hardware-in-the-loop simulation) concept, consisting in closed-loop connecting physical and software parts, in order to replicate in laboratory conditions the dynamic behaviour of an industrial process. The software part results from modelling the real system to be simulated, whereas the physical part is taken as it is from this system. Principles of HILS systems are first presented, then a systematic design procedure is proposed and illustrated by building a simulator dedicated to variable-speed wind energy conversion systems. The architecture and possibilities of this simulator are suggested by amply discussing the most relevant experimental results. Some concluding remarks finish this paper.

International audience; In this paper, we consider MAC (media access control) protocols appropriate to the underwater acoustic networks. First, we consider a media access method based on the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol used in the wireless local area networks IEEE 802.11 (WiFi). In the underwater acoustic channel, the acoustic wave propagates very slowly with regard to the electromagnetic wave (about 1500 m s ). Therefore the propagation delay is significant and thus collisions present a high cost considering the delay of transmission and the available throughput. To avoid this problem, we consider a second protocol in which we integrate a WAIT command [1]. Finally we integrate to our proposition a power control mechanism in order to increase network performance (delay, throughput). The performance evaluation of the three propositions has been done in terms of available throughput of the underwater sensors, delay of transmission and collision probability. The proposed simulation system model is detailed.

This paper experimentally investigates the parametric instability of an industrial axially moving belt subjected to multifrequency excitation. Based on the equations of motion, an analytical perturbation analysis is achieved to identify instabilities. The second part deals with an experimental set-up that subjects a moving belt to multi-frequency parametric excitation. A data acquisition technique using optical encoders and based on the angular sampling method is used with success for the first time on a non-synchronous belt transmission. Transmission error between pulleys, pulley/belt slip and tension fluctuation are deduced from pulley rotation angle measurements. Experimental results validate the theoretical analysis. Of particular note is that the instability regions are shifted to lower frequencies than the classical ones due to the multi-frequency excitation.Copyright © 2007 by ASME

The eXtended Finite Element Method (X-FEM) has been applied to a wide range of applications, in particular for crack growth simulations in structural mechanics. However, for real applications (engineering simulations,...), even if one does not need to mesh the crack, it is necessary to take into account the different spatial scales linked to the size of the domain, the geometry of the boundary, the size of the boundary with prescribed displacement or loading, the discretized "representation" of the crack,... In this respect, one proposes in this paper to couple the eXtended Finite Element Method with a multi-grid strategy. Details are given for numerical implementation with a hierarchical finite element strategy. Finally, some examples are given (mixed mode crack growth simulations) to validate the method.