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International audience; Additive manufacturing (AM) technology has been identified as one of the major digital innovations that has revolutionized not only the field of the industry but also the construction. From a research side, AM is a multi-disciplinary domain, combining between materials science, mechatronics engineering and architectural design. The AM concept needs to consider the geometry and the shape of printed objects in regards of material properties and robot kinematics which are adaptable to the object size. In this paper, we present an integrated design and control of an omnidirectional Mobile Manipulator Robot (MMR), capable of extruding concrete and clay materials, to print complex and funicular architectural geometries. The studied robot allows printing building pieces with different shapes and sizes by additive deposit which can later be assembled on-site. The main issue concerns the control of continuous material deposit, with specified accuracy and respecting the desired shape. This problem involves to solve, in real-time, the non-linear kinematic model of a 10 Degrees of Freedom (DoF) heterogeneous robot. The kinematic model and the control of utilized MMR are discussed, and an optimization method based on quadratic programming is used for handling the robot redundancy. Finally, we present the experimental results to illustrate the efficiency of AM on the developed concept.

International audience; Prostate Cancer is one of the most prevalent cancers in men and a leading cause of death. Prostate Brachytherapy (BT) is one of the promising treatment techniques. The use of BT techniques is made easier, thanks to the developments of associated imaging technologies like Ultrasound and Magnetic Resonance Imaging (MRI). MRI has the capacity to detect small lesions providing a wider scope of research and enabling better accuracy in BT treatments. In order to enhance the diagnosis of prostate cancer and its treatment options in the 2 seas region, Europe, Interreg 2 Seas co-financed a European Union Project Cooperative Brachytherapy called CoBra. The aim of the CoBra project is to perform a robotized biopsy and BT under real-time MRI-guidance. The concept is under development, such as the robot's task should be achieved within the MRI-scanner without any repositioning of the patient.

International audience; This paper proposes a method to reach the equivalence between an IMC and a PI controller regardless of the model order. To this end, the key idea consists of using a specific IMC filter that exhibits a good level of robustness and further leads to get a structure of a PI controller whatever the order of the model is. The developed procedure constitutes the main contribution of this paper. To meet given set of specifications, the controller parameters are tuned through a straightforward analytic way using the dynamics of the tracking error. Furthermore, in order to evaluate the efficiency level of this procedure, an application to control an autonomous vehicle is described and the simulation results are shown to be satisfactory.

International audience; In this paper, we propose a novel energy detection (ED) receiver architecture combined with time-of-arrival (TOA) estimation algorithm, compliant to the IEEE 802.15.4a standard. The architecture is based on double overlapping integrators and a sliding correlator. It exploits a series of ternary preamble sequences with perfect autocorrelation property. This property ensures coding gain, which allows an accurate estimation of power delay profile (PDP). To improve TOA estimation, the interpolation of PDP samples is proposed and the architecture is validated by using an ultra-wideband signals measurements platform. These measurements are carried out in line-of-sight and non-line-of-sight multipath environments. The experimental results show that the ranging performances obtained by the proposed architecture are higher than those obtained by the conventional architecture based on a single-integrator in both LOS and NLOS environments.

International audience; An experimental study is carried out to investigate the different stages of the evaporation phenomenon of a methanol drop that exhibits a complex behavior because of its high volatility. An optical technique is employed with top and side view cameras; it allows to follow the drop shape evolution and determine the geometric parameters: contact angle and base diameter from which the volume of the droplet is computed. The outcomes of this study show three distinct stages. First, the evaporation kinetics is very fast (33% of the droplet lifetime) where 85% of the volume evaporates with a nearly pinned contact line. It is followed by a short stage (12% of lifetime) where 8% of the volume evaporates. In this stage, the drop forms a thin liquid film followed by a motion of the contact line in which the drop retracts. The wetting surface deforms and loses its quasi-circular shape. Then, the wetting area shrinks drastically to form a smaller droplet with a higher contact angle. In the third stage (55% of lifetime), the 7% remaining drop volume evaporates with a low evaporation rate accompanied by a strong decrease of contact angle and a slight decline of wetting area until total evaporation.

International audience; —This paper deals with the forward kinematic calibration of a bionic arm inspired from the organic elephant trunk and called compact bionic handling assistant (CBHA). First, a forward kinematic model is developed based on the principle of the constant curvature continuum robot theory. Then, two experimental setups are proposed in order to carry out the model calibration and validation. The first one is based on the trilateration method, while the second one is based on the coupling of the CBHA with a rigid six-degree-of-freedom rigid manipulator. The aim of the calibration is to enhance the precision of the forward kinematic model.

International audience; In this article, we propose an optimization process able to generate optimal kinematic configuration for spatial hyper-redundant manipulators with multiple rigid parallel modules. The proposed method uses a deterministic optimization scheme that evaluates the score of trial kinematic configurations while accounting for various geometric constraints. This versatile method is based on a simultaneous search for both the best curve capturing the overall kinematic robot posture and the platform distribution along this curve. This process is carried out using the powerful sequential quadra-tic programming technique. Numerical results are presented to illustrate the efficiency of the proposed approach. Finally, this model was validated by real measurements obtained with the continuum bionic handling arm of a mobile robot called Robotino-XT.

In this paper, we treat the problem of trajectory planning of an unmanned ground vehicle evolving on an uneven terrain. In such environment, the role of the suspension system cannot be neglected and a vehicle vertical model has to be taken into account. In the present work, we present three reduced models with different level of complexity. These models make possible to handle the constraints inherent to stability, embedded equipment safety and suspension mechanical integrity. An optimization problem is also formulated in order to define the optimal speed profile for a safety behaviour of the mobile robot.

International audience; In this paper, we tackle the problem of Arabic complex Question Answering (QA), where models are required to reason over multiple documents to find the answer. Indeed, no Arabic dataset is available for this type of questions. To fill this lack, we propose a new approach to automatically generate a dataset for Arabic complex question answering task. The proposed approach is based on using an effective workflow with a set of templates. The generated dataset, denoted as ACQAD, contains more than 118k questions, covering both comparison and multi-hop types. Each question-answer pair is decomposed into a set of single-hop questions, allowing QA systems to reduce question complexity and explain the reasoning steps. We then provide a statistical analysis of the produced dataset. Afterwards, we will make the corpus available to the international community.

International audience; We present a new interface for minimally invasive surgery (MIS) training that incorporates novel broadband sensory modalities that include visual, force, and thermal technology, into the evolution of the next generation of surgical robotics and simulators. A new haptic device is designed to provide high force and torque capabilities for a better touch feedback. Part of the surgical tool is kept to be the real grasper (i.e., the handle) of the haptic interface. Yet, our main novel contribution is in integrating thermal feedback in MIS applied perspectives; indeed, thermal sensing finds particular utility in detecting and isolating unstable arterial plaque and tumors. In addition, thermal energy is used in several therapeutic procedures such as tumor ablation or tissue welding. We propose several thermal exchange models based on the Pennes'bioheat transfer equation. The overall haptic interface (force and thermal display) is interfaced with an open source virtual reality simulator (the SOFA framework). We added in SOFA the necessary models dealing with thermal simulation using built-in data structure and methods. The integration is successful, and realistic simulation scenarios combining visual, thermal, and force feedback were achieved. Results using the overall simulation are presented and evaluated

In this paper, we simplify the architecture of the cell averaging constant false alarm rate (CA-CFAR) approach used in time-of-arrival (TOA) estimation for impulse radio ultra wideband (IR-UWB) systems. The CA-CFAR approach uses the received signal samples provided by the non-coherent energy detection (ED) receivers. The modified approach is evaluated by Monte Carlo simulation on the CM1 channel model of the standard IEEE802.15.4a. The effects of the reference cells number and the guard cells duration on the performances of the modified CA-CFAR approach are studied. The simulation demonstrates that the modified approach gives better results than the conventional approaches.

International audience; An important challenge to any image pixels classification system is to correctly assign each pixel to its proper class without blurring edges delimiting neighboring regions. In this paper, we present an aerial image mapping approach that advantageously combines unsupervised segmentation with a supervised Markov model based recognition. The originality of the proposed system carries on three concepts: the introduction of an auto-adaptive circular-like window size while applying our stochastic classification to preserve region edges, the extension of the Dependency Tree-HMM to permit the computation of likelihood probability on windows of different shapes and sizes and a mechanism that checks the coherence of the indexing by integrating both segmentations results: from unsupervised over segmentation, regions are assigned to the predominating class with a focus on inner region pixels. To validate our approach, we achieved experiments on real world high resolution aerial images. The obtained results outperform those obtained by supervised classification alone.

International audience; An important challenge to any image pixels classification system is to correctly assign each pixel to its proper class without blurring edges delimiting neighboring regions. In this paper, we present an aerial image mapping approach that advantageously combines unsupervised segmentation with a supervised Markov model based recognition. The originality of the proposed system carries on three concepts: the introduction of an auto-adaptive circular-like window size while applying our stochastic classification to preserve region edges, the extension of the Dependency Tree –HMM to permit the computation of likelihood probability on windows of different shapes and sizes and a mechanism that checks the coherence of the indexing by integrating both segmentations results: from unsupervised over segmentation, regions are assigned to the predominating class with a focus on inner region pixels. To validate our approach, we achieved experiments on real world high resolution aerial images. The obtained results outperform those obtained by supervised classification alone.

In this paper, we propose a new joint time-of-arrival estimation and non-line-of-sight identification approach for ultra-wideband wireless sensor network applications. We use an energy-based time-of-arrival estimation algorithm. The non-line-of-sight detection is based on the direct path to the strongest multipath components ratio of the received signal folded version of the energy-based time-of-arrival estimation algorithm. The non-line-of-sight information is used in the weighted least-squares localization algorithm. The channel models residential LOS and residential NLOS of the standard IEEE802.15.4a are used. Numerical simulations results show that the correct identification of channel models with the proposed approach is better than those based on joint likelihood ratio and the location accuracy obtained by weighted least-squares algorithm using non-line-of-sight information is higher than that obtained by least-square algorithm.

International audience; In this paper we address the problem of mobile robot formation control. Indeed, the most work, in this domain, have studied extensively classical control for keeping a formation of mobile robots. In this work, we design an FLC (Fuzzy logic Controller) controller for separation and bearing control (SBC). Indeed, the leader mobile robot is controlled to follow an arbitrary reference path, and the follower mobile robot use the FSBC (Fuzzy Separation and Bearing Control) to keep constant relative distance and constant angle to the leader robot. The efficiency and simplicity of this control law has been proved by simulation on different situations.

In this paper we evaluate the statistical performances of the association of a low-complexity of the time of arrival (TOA) estimation algorithm and the location estimation algorithm in a non line-of-sight (NLOS) indoor environment. For that, we choose the time hopping (TH) code and pulse amplitude modulation (PAM) for ultra wideband (UWB) symbols and the IEEE802.15.3a models (CM1 and CM3) for the channel propagation. The numerical simulations show that the accuracy of TOA estimation can be achieved with only one training symbol period for data aided (DA) mode in LOS propagation (CM1). These performances are seriously degraded in NLOS propagation (CM3). Otherwise, the obtained results show the harmful effect of increasing the number of NLOS nodes (basic stations) on the positioning accuracy.

In this article we address the problem of mobile robot formation control. Indeed, the most work, in this domain, have studied extensively classical control for keeping a formation of mobile robots. In this work, we design an FLC (Fuzzy logic Controller) controller for separation and bearing control (SBC). Indeed, the leader mobile robot is controlled to follow an arbitrary reference path, and the follower mobile robot use the FSBC (Fuzzy Separation and Bearing Control) to keep constant relative distance and constant angle to the leader robot. The efficiency and simplicity of this control law has been proven by simulation on different situation., {"references": ["", "Kar-Han Tan , M.A.Lewis, \u00d4\u00c7\u00ff-Virtual structures for high precision cooperative control--, technical report, Computer Science Department, University of California, Los Angles, 1997.", "W. Ren, R. W. Beard, \"A Decentralized scheme for spacecraft formation flying via the virtual structure approach\", AIAA Journal of Guidance, Control, & Dynamics, Revised Submission, June 2003.", "M. Egerstedt, K. Hu \u00d4\u00c7\u00ff-Formation constrained multi-agent control--, proceedings of 2001 IEEE International Conference on Robotics and Automation, pp .3961-3966, Seoul, Korea, May 21-26, 2001.", "J.M. Esposito, V. Kumar, \u00d4\u00c7\u00ff-A formalism for parallel composition of reactive and deliberative control objectives for mobile robots--, technical report, Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, 2000.", "H.Yamgachi, \u00d4\u00c7\u00ff-A Cooperative Hunting Behavior by Mobile Robot Troops--, ICRA-98 pp.3204-3209, Leuven Belgium, May 1998", "K. Sugihara and I. Suzuki, \"Distributed algorithms for formation of geometric patterns with many mobile robots\", J. Robot. Syst., Vol. 9, pp.777-790, 2001.", "Jose Sanchez and Rafael Fierro, \u00d4\u00c7\u00ff-Sliding mode control for robot formations--, Proc. IEEE Int. Symposium on Intelligent Control, Oct. 2003, pp.438-443.", "Xiaohai Li, Jizong Xiao, Zijun Cai, \u00d4\u00c7\u00ff-Backstepping based multiple mobile robots formation control--, 2005 IEEE/RSJ International Conference on Intelligent Robots and Systems, pp.1313-1318.", "A. Luca, G. Oriolo and M. Vendittelli, ÔÇÿ-Control of wheeled mobile robots: An experimental overview--, in RAMSETE - Articulated and Mobile Robotics for Services and Technologies, S. Nicosia, B. Siciliano, A. Bicchi and P. Valigi, Eds. Springer-Verlag, 2001. [10] G. Oriolo, A. Luca and M. Vandittelli, ÔÇÿ-WMR control via dynamic feedback linearization: design, implementation, and experimental v validation--, IEEE Transactions on Control Systems Technology, vol. 10, no. 6, pp. 835-852, 2002. [11] G. Klan\u2500ìar, D Matko, S. Bla\u017ei\u2500ì, ÔÇÿ-Mobile robot control on a reference path--, Proceedings of the 13th Mediterranean Conference on Control and Automation Limassol, Cyprus, June 27-29, 2005, pp 1343-1348 [12] Y. Kanayama, Y. Kimura, F. Miyazaki, and T. Noguchi, “A stable tracking control scheme for an autonomous mobile robot," in Proceedings IEEE International Conference on Robotics and Automation, 1990, pp. 384-389. [13] S. G. Tzafestas and G. G. Rigatos, “A simple robust sliding-mode fuzzy logic controller of the diagonal type," J. Intelligent Robotic Systems, vol. 26, pp. 353-388, 1999. [14] Okyay Kaynak, Kemalettin Erbatur, and Meliksah Ertugrul, ÔÇÿ-The fusion of computationally intelligent methodologies and sliding-mode controlsurvey-- IEEE Transactions on Industrial Electronics, Vol. 48, No. 1, February 2001 pp. 4-17. [15] T.-H. S. Li and M.-Y. Shieh, “Switching-type fuzzy sliding mode control of a cart-pole system," Mechatronics, vol. 10, pp. 91-109, 2000."]}

International audience; The problem of blind joint FIR-MIMO channel and data estimation is addressed in this paper. Based on a regularized DML (Deterministic Maximum Likelihood) formulation of the problem, a bilinear approach is used in order to estimate jointly the channel impulse responses and the input data. This regularization is introduced as a penalty function added to the classical DML criterion representing the a priori information about the problem in order to enhance the accuracy of the estimation. Two types of priors information are considered for the transmitted data: the finite alphabet simplicity or the sparsity. The sparsity prior was also considered for channel impulse responses. The key advantage of the proposed criteria is their convexity when optimized alternatively over the channel and the input data. The proposed approach allows to improve further the estimation accuracy of such a blind estimation problem but suffers from a relatively high computational cost. Hence, a reduced complexity implementation of the latter has been proposed at the end of the paper, in an adaptive scheme for high dimensional or streaming data situations.

International audience; Millimeter-wave (mmWave) and multiple-input multiple-output (MIMO) combination technologies have attracted extensive attention from both academia and industry for meeting future communication challenges and requirements. As a viable option to deal with the trade-off between hardware complexity and system performance, hybrid analog/digital architectures are regarded as efficient mmWave MIMO transceivers. While acquiring channel state information (CSI) is a challenging task to design the optimal beamformers/combiners, especially in mmWave communications due to a lot of challenges. Fortunately, the sparse nature of the channel allows to leverage the compressed sensing (CS) tools and theories. However, the critical challenge to develop a CS-based formulation for estimating the mmWave channel is the codebook design (sensing matrices) and its pilot symbol numbers. In this paper, we proposed a multistage CS-based algorithm to estimate the channel explicitly using pilot and data symbols which enable increasing the number of measurements to enhance the estimation accuracy and maximize the spatial diversity by reducing the overlapping between training beams. Simulations confirmed that our proposed method has the best results compared to the existing methods based on codebook schemes.

While traditional data mining techniques have been used extensively for finding patterns in databases, they are not always suitable for incorporating user-specified constraints. To overcome this issue, CP and SAT based frameworks for modeling and solving pattern mining tasks have gained a considerable audience in recent years. However, a bottleneck for all these CP and SAT-based approaches is the encoding size which makes these algorithms inefficient for large databases. This paper introduces a practical SAT-based approach to discover efficiently (minimal non-redundant) association rules. First, we present a decomposition-based paradigm that splits the original transaction database into smaller and independent subsets. Then, we show that without producing too large formulas, our decomposition method allows independent mining evaluation on a multi-core machine, improving performance. Finally, an experimental evaluation shows that our method is fast and scale well compared with the existing CP approach even in the sequential case, while significantly reducing the gap with the best state-of-the-art specialized algorithm.

International audience; Recently, the number of electric vehicles (EVs) is increasing due to the declining of oil resources and rising of greenhouse gas emission. However, EVs have not received wide acceptance by consumers due to the limitations of the stored energy and charging problems in batteries. The dynamic or in motion charging solution becomes a suitable choice to solve the battery related issues. Many researchers and vehicle manufacturers are working to develop an efficient charging system for EVs which is based on magnetic emissions to transfer power. These emissions must be evaluated and compared to limits specified by standards (in and outside the vehicle) in order to not cause harmful effects on their environment (humans, pets, electronic devices...). This paper presents an efficient method for modeling electromagnetic emission in near field and sizing a magnetic shield for a wireless power transfer (WPT) system for EVs. A model based on elementary magnetic dipoles is developed in order to obtain the same radiation as the real WPT coil. This model is used to size a magnetic shield which will be placed under the vehicle to protect human body from magnetic emissions. The obtained shielding plate allows to respect the standards of magnetic emission by bringing a decrease of 43 dB to the levels of magnetic fields. This approach is experimentally validated.

International audience; Flapping foil energy harvesting systems are considered as highly competitive devices for conventional turbines. Several research projects have already been carried out to improve performances of such new devices. This paper is devoted to study effects of non-sinusoidal heaving trajectory, non-sinusoidal pitching trajectory, and the effective angle of attack on the energy extraction performances of a flapping foil operating at low Reynolds number (Re=1100). An elliptic function with an adjustable parameter S (flattening parameter) is used to simulate various sinusoidal and non-sinusoidal flapping trajectories. The flow around the flapping foil is simulated by solving Navier–Stokes equations using the commercial software Star CCM+ based on the finite-volume method. Overset mesh technique is used to model the flapping motion. The study is applied to the NACA0015 foil with the following kinetic parameters: a dimensionless heaving amplitude h0 = 1c, a shift angle between heaving and pitching motions f = 90 , a reduced frequency f = 0:14, and an effective angle of attack amax varying between 15 and 50 , corresponding to a pitching amplitude in the range q0 = 55:51 to 90:51 . The results show that, the non-sinusoidal trajectory affects considerably the energy extraction performances. For the reference case (sinusoidal heaving and pitching motions, Sh = Sq = 1), best performances are obtained for the effective angle of attack, amax = 40 . At small effective angle of attack amax < 30 , the non-sinusoidal pitching motion combined with a sinusoidal heaving motion, greatly improve energy extraction performances. For amax = 15 , Sh = 1 and Sq = 2, energy extraction efficiency is improved by 52.22% and the power coefficient by 70.40% comparatively to sinusoidal pitching motion. At high effective angles of attack ( amax >40 ), non-sinusoidal pitching motion has a negative effect. Performance improvement is quite limited with the combined motions non-sinusoidal heaving/sinusoidal pitching.

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International audience; The primary aim of this study is to investigate the influence of an upstream cylindrical rod on the laminar separated boundary layer that develops on a symmetrical profile wing operating at a Reynolds number of Re c = 4.45 × 10 5. To get further insight onto the aerodynamic performances of this wing at low Reynolds number, numerical simulations with a transitional turbulence model are performed with the ANSYS-Fluent software. The passive flow control technique is applied by setting up a cylindrical rod of diameter d upstream of a NACA-0012 airfoil of chord lenght c. The dimensionless rod diameter with respect to the chord length is d/c = 2/150. Simulations are carried out over a wide range of angles of attack for both the baseline case and the controlled case by the passive proposed technique. The effects of the wing incidence on the parietal pressure distributions on the suction surface of the wing are examined. The results show that the Laminar Separation Bubble that is formed on the upper surface is moving upstream toward the leading edge as the incidence is increased. Moreover, qualitative analysis of the transition zone revealed that presence of the wing in the rod wake exerted considerable effect on the pressure coefficient. Particularly, this passive turbulence generator contributes to eliminate the boundary layer separation

The heterogeneity and complexity of lignin necessitate a deep understanding to select the most appropriate lignin valorization and convert it into value-added products. The objective of this research is to investigate the features of organosolv and Kraft lignins, in order to understand the effects of the sources and the isolation treatment, through the comparison of physicochemical and thermal properties. Various techniques have been employed such us Fourier transform infrared spectroscopy (FTIR), carbon solid state nuclear magnetic resonance 13CNMR, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. It was found that lignin produced from the hardwood using the Kraft process provided the greatest yield compared to other combinations. Softwood pretreatments achieve almost higher sugar yield than hardwood treatments. The infrared spectroscopy analysis confirms the existence of different monolignols. Organosolv lignins showed a predominance of guaiacyl and syringyl units. To provide additional information, the principle components analysis, as a powerful chemometric method, has also been applied to evaluate the FTIR data. NMR spectroscopy of lignins demonstrated the presence of essential functional chemical groups. It is also revealed that the nature of the treatment and the source of lignin samples affect the thermal properties. Overall, lignin isolated from Aleppo pine using Kraft process presented better thermal stability than that of organosolv lignin.

The most critical issues faced by the world nowadays is to provide the sustainability of consumption for energy and natural resources. Lignin is said to be one of the alternative new discoveries best-suited lignocellulosic biomass due to its low cost, sufficient availability and environmentally safe. The valuable properties exhibited by lignin can give broader applications usage such as in composite materials, wood industries, polymer composite industries, pharmaceutical and corrosion inhibitor industries. Many biomass wastes resources, isolation processes and treatments are undergoing development in order to enhance the producing new lignin-based materials on an industrial scale. Therefore, this review discussed on the current knowledge on the structure and chemistry of isolation of lignin from different sources using various common methods, its characterization, properties and its applications.

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This paper deals with the control and implementation of a bidirectional Z-source inverter for a photovoltaic-diesel generator-energy storage hybrid system. The proposed control strategy is based on the voltage regulation across one of the Z-network capacitor (Vcz), through a buck-boost converter of the storage system side. In some critical situations, where the load power is important, the Vcz voltage regulation is no longer able to ensure the duration of the necessary state shoot-through for the maximum power point tracking achievement. In this context, the diesel generator can therefore be solicited to ensure the shoot-through duration and achieve maximum power point tracking so that it can be used more advantageously without any harmful effects on the Z-source inverter operation. The effectiveness of the proposed control strategy is evaluated and validated by extensive simulations and experiments.

Over the past few years, nanocellulose (NC), cellulose in the form of nanostructures, has been proved to be one of the most prominent green materials of modern times. NC materials have gained growing interests owing to their attractive and excellent characteristics such as abundance, high aspect ratio, better mechanical properties, renewability, and biocompatibility. The abundant hydroxyl functional groups allow a wide range of functionalizations via chemical reactions, leading to developing various materials with tunable features. In this review, recent advances in the preparation, modification, and emerging application of nanocellulose, especially cellulose nanocrystals (CNCs), are described and discussed based on the analysis of the latest investigations (particularly for the reports of the past 3 years). We start with a concise background of cellulose, its structural organization as well as the nomenclature of cellulose nanomaterials for beginners in this field. Then, different experimental procedures for the production of nanocelluloses, their properties, and functionalization approaches were elaborated. Furthermore, a number of recent and emerging uses of nanocellulose in nanocomposites, Pickering emulsifiers, wood adhesives, wastewater treatment, as well as in new evolving biomedical applications are presented. Finally, the challenges and opportunities of NC-based emerging materials are discussed.

To ensure the synchronization process in a hybrid PV-Diesel generation system parallel topology, a phase-locked loop is generally used to estimate the angular frequency of the point of common coupling. However, the DG rotor inaccessibility imposes its operation mode as a master. This will therefore affect the system overall stability since the phase-locked loop is affected by oscillations, which are predicted by the power-angle curve concept interacting with the DG rotary inertia. In this context, this paper proposes a new control strategy based on virtual synchronous generators for a stand-alone PV-Diesel hybrid generation system to synchronize the output voltages without a phase-locked loop, while correcting the diesel generator rotor initial position and ensuring power sharing between the two sources, according to a desired power ratio. To prove the effectiveness of the proposed control strategy, simulation and experiments are carried out. The achieved results clearly illustrated the feasibility and the improvement brought by the proposed virtual synchronous generators-based control strategy.

As everyone knows, the electromagnetic interference (EMI) modeling becomes more important over time. So far, many EMI models have been developed in power electronics. Almost all of them are composed of two to three impedances as well as two current or voltage sources. What distinguishes a model from another is especially its identification method, which in fact determines the most of its performances. In this paper, a new three-terminal EMI model is proposed for DC-DC converters. This model is very easy to identify, and takes into account the converter impedance behavior. The model thus proposed is a complete representation of the conducted emission behavior of the converter, where it takes not only the level of the interfering line and neutral signals, but also the complete impedance behavior of the converter. Experimental illustrations are also included to verify the validity of the proposed model. Comparison between measured and predicted results under different operating conditions with and without filter, shows that the proposed model is able to successfully predict conducted emissions up to 100 MHz with an error not exceeding 6 dB in the worst case.

International audience; The objective of this work is to initiate the discussion about multiphysics relationships between the molten and solid states of high-density polyethylene (HDPE). The extrusion and the injection processes are employed to prepare samples, and the experimental procedures, using differential scanning calorimetry, dynamic thermomechanical analysis (DMTA), thermal gravimetric analysis, and rheological measurements, are defined to choose the optimal variables. After different characterizations, the extrusion and injection temperatures of 220 and 230 °C have been chosen. To investigate the viscoelastic behavior of HDPE, the DMTA is used. To perform the high strain rate tensile tests, tensile machine was equipped with a specific furnace. Two temperatures, −20 and 20 °C, with strain rates varying from 0.001 to 100 seconds−1 were used to compare the flow characteristics. Results showed that by increasing the strain rate the molecular mobility of the HDPE chains is decreased. In addition, to the tests at −20 °C, the increase of Young's modulus can be properly observed, under high strain rates.

International audience; In this study, numerical investigations on the energy extraction performance of a flapping foil device are carried out by using a modified foil shape. The new foil shape is designed by combining the thick leading edge of NACA0012 foil and the thin trailing edge of NACA0006 foil. The numerical simulations are based on the solution of the unsteady and incompressible Navier-Stokes equations that govern the fluid flow around the flapping foil. These equations are resolved in a two-dimensional domain with a dynamic mesh technique using the CFD software ANSYS Fluent 16. A User Define Function (UDF) controls the imposed sinusoidal heaving and pitching motions. First, for a validation study, numerical simulations are performed for a NACA0012 foil undergoing imposed heaving and pitching motions at a low Reynolds number. The obtained results are in good agreement with numerical and experimental data available in the literature. Thereafter, the computations are applied for the new foil shape. The influences of the connecting area location between the leading and trailing segments, the Strouhal number and the effective angle of attack on the energy extraction performance are investigated at low Reynolds number (Re = 10 000). Then, the new foil shape performance was compared to those of both NACA0006 and NACA0012 baseline foils. The results have shown that the proposed foil shape achieves higher performance compared to the baseline NACA foils. Moreover, the energy extraction efficiency was improved by 30.60% compared to NACA0006 and by 17.32% compared to NACA0012. The analysis of the flow field around the flapping foils indicates a change of the vortex structure and the pressure distribution near the trailing edge of the combined foil compared to the baseline foils.

Axial flow fans are used in many fields in order to ensure the mass and heat transfer from air, chiefly in the heating, ventilation and air conditioning industry (HVAC). A more proper understanding of the airflow behavior through the systems is necessary to manage and optimize the fan operation. Computational fluid dynamics (CFD) represents a real tool providing the ability to access flow structures in areas that measuring equipment cannot reach. Reducing the leakage flow rate, inherent in operation, by synthetic-jet techniques improves performance. This paper presents the CFD results performed on a hollow blade fan developed by our team. The leakage flow is controlled by blowing air from 16 designated circular holes and arranged on the fan shroud. We discuss the results for two rotational speeds (1000 and 2000 rpm) and two injection rates (400 and 800 L/min). The numerical results consistent with the experimental show, for the low rotation speed and high injection ratio, significant gains in power (53%), torque (80%) and leakage flow rate (80%).

A heterogeneous wireless environment is composed of different radio access technologies (RATs) including IEEE standards (e.g., Wi-Fi) and 3GPP (e.g., 2G, 3G, 4G, 5G), each with different coverage and different capacity to cater for diverse service requirements. In such an environment, multiple access networks could be available for a mobile user. Each user can run multiple applications that have particular Quality of Service (QoS) requirements. Hence, it would be beneficial for a multi-interface terminal to simultaneously use two or more interfaces to gain in performance. However, using multiple networks simultaneously may consume more energy than using only one interface. Therefore, energy consumption should be considered as a criterion in the Flow/Interface Association (FIA). This paper presents a novel method called Smart Tabu Search (STS) that takes into account network conditions, the monetary cost of the network, QoS requirements of the applications, user preferences, and energy consumption of the mobile device to select the optimal FIA that achieves the best trade-off among all the considered criteria. We validate our proposal using both simulations and testbed experiments.

Predicting the expected performance of Wireless Sensor Networks (WSNs) is the key to their successful deployment. This paper investigates the following fundamental problem: how to judiciously plan the physical and the logical topologies of a WSN so that performance demands including network connectivity, sensing coverage quality, reliability, and lifetime are all satisfied with the least possible cost. To handle the uncertainty related to sensor connectivity and coverage, we devise a probabilistic-based communication cost model, and we exploit the belief functions theory to define a generic evidence fusion scheme that captures several characteristics of real-world applications. The uncertainty-aware cluster-based WSNs deployment problem is formulated as a multi-objective binary nonlinear and non-convex optimization problem, and an efficient heuristic using genetic algorithms is investigated. Using both simulations and testbed-based experiments, we show that the proposed deployment approach can fulfill the user performance needs, which confirms that the deployment of real-world fusion-based WSNs with predictable performance is possible.

International audience; A homogeneous continuous sliding mode control scheme based on finite time stability is developed in this paper for an upper limb exoskeleton robot dedicated for rehabilitation. Indeed this type of robot interacts directly with human limbs whose dynamics are unknown and different for users. Therefore, the main idea is to provide a robust motion control of the exoskeleton robot using a continuous higher order sliding mode controller despite parameters variations, uncertainties and external disturbances. The proposed controller combines the homogeneity concept and the super-twisting algorithm. Finite time stabilization is achieved using the first part of the controller while disturbance rejection is granted by the second part of the controller. Performance of the controller and its robustness are illustrated through simulations of trajectory tracking tests corresponding to passive rehabilitation exercises.

International audience

International audience

International audience; The effect of nonsinusoidal trajectory on the propulsive performances and the vortex shedding process behind a flapping airfoil is investigated in this study. A movement of a rigid NACA0012 airfoil undergoing a combined heaving and pitching motions at low Reynolds number (Re¼11,000) is considered. An elliptic function with an adjustable parameter S (flattening parameter) is used to realize various nonsinusoidal trajectories of both motions. The two-dimensional (2D) unsteady and incompressible Navier–Stokes equation governing the flow over the flapping airfoil are resolved using the commercial software STAR CCMþ. It is shown that the nonsinusoidal flapping motion has a major effect on the propulsive performances of the flapping airfoil. Although the maximum propulsive efficiency is always achievable with sinusoidal trajectories, nonsinusoidal trajectories are found to considerably improve performance: a 110% increase of the thrust force was obtained in the best studied case. This improvement is mainly related to the modification of the heaving motion, more specifically the increase of the heaving speed at maximum pitching angle of the foil. The analysis of the flow vorticity and wake structure also enables to explain the drop of the propulsive efficiency for nonsinusoidal trajectories.

International audience; The current paper presents a two scale Finite Element approach (FE 2 ), adopting the periodic homogenization method, for fully coupled thermo-mechanical processes. The aim of this work is to predict the overall response of rate-dependent, non-linear, thermo-mechanically coupled problems of 3D periodic composite structures. The material constituents implicated in the analyses obey generalized standard materials laws, while the characteristic equations of the problem (balance law, first law of thermodynamics) are expressed and satisfied in both microscopic and macroscopic scales. For the numerical implementationin both scales, the finite element commercial software ABAQUS is utilized in the framework of small strains and rotations. A set of dedicated scripts and a specially designed Meta-UMAT subroutine allow the connection between the macroscopic structure and the microscopic unit cells attached to every macroscopic integration point. The two-scale finite element framework is applied to simulate thermoelastic-viscoplastic materials of complex 3D composite structures, and its capabilities are demonstrated withproper numerical examples. It is worth mentioning that the proposed computational strategy can be applied for any kind of 3D periodic microstructure and non-linear constitutive law.

In this paper, we propose a robust and novel approach for auto-adaptive pseudo noise PN code serial acquisition based on Order Statistic Constant False Alarm Rate (OS-CFAR) for mobile communication systems over multipath environment. The new approach is called Automatic Selection Order Statistic (ASOS)-CFAR. It uses all available information based on the ML estimation to identify automatically the ranked cell from ranked data cells that indicates the discrimination between homogeneous and non-homogeneous environments, in order to use it to compute the adaptive threshold. Monte- Carlo simulations in a multipath environment indicate that the proposed approach has a high ability to sense the mobile communications environments, thus getting to produce a correct detection decision, without requiring any prior knowledge regarding the number of multipath signals.

In this paper, we present a design of an all-fiber source of correlated photon pairs based on standard telecommunications tapered fibers. We examine the generation of correlated photon pairs using parametric process χ ( 2 ) in silica tapered optical fibers. This nonlinear process is ensured thanks to surface dipole and bulk multipole nonlinearities. The process of photon creation is modeled by taking into account the vector aspect of the propagation of the optical field in a silica nanofiber. The phase matching is provided by propagating the pump field in one spatial mode while generating a photon pair in another spatial mode. The generation efficiency of photon pairs depends on diameter uniformity of the nanofiber after the manufacturing process. We size this nanofiber for a good optimization of photon pair generation efficiency, and we report that the tolerance in diameter uniformity is Δ d = 2 n m for a generation rate of photon pairs estimated to N ph ≈ 22 000 p a i r s / s , for 1 W power pump and a nanofiber length of 1.1 mm. Deposits on the nanofiber can be used in order to relax the manufacturing constraints on diameter to maximize the generation rate of photon pairs. As an example, the use of polytetrafluoroethylene on the nanofiber applied as a cladding whose thickness is infinite makes it possible to relax the constraints on the nanofiber diameter. For the same Δ d = 2 n m , a generation rate of photon pairs estimated to N ph ≈ 78 000 p a i r s / s for 1 W power pump and a nanofiber length of 2.4 mm is predicted.

International audience; This paper presents an experimental approach aimed at analyzing and validating a two-scale nonlinear Finite Element (FE 2 ) simulation of a 3D composite structure. The studied composite material consists of polyamide thermoplastic matrix, exhibiting viscoelastic-viscoplastic behavior with ductile damage, reinforced by woven glass fabric whereby inelastic and anisotropicdamage behavior is considered. The multiscale parallel computation is founded on the periodic homogenization at the microscopic scale, which considers the geometric description of the reinforcement’s architecture and accounts for time-dependent and non-linear local behavior of each constitutive phase. For the numerical implementation at microscopic and macroscopic scales, an advanced UMAT subroutine is developed and combined with a parallelization technique in the commercial software Abaqus/Standard. The multilevel computation is achieved simultaneously at both scales (microscopic and macroscopic) through an incremental scheme. Numerical results of the FE multiscale simulation are analyzed and compared with the experimental results obtained for different stacking sequence configurations of a 3D woven composite holed plate subjected to tension. Besides the good agreement between the experimental and the predicted load-displacement global responses, the numerical simulation of the macroscopic strain fields reasonably agrees with those measured experimentally through the Digital Image Correlation (DIC) technique. Furthermore, the performance and the capabilities of the multiscale (FE 2 ) strategy are demonstrated getting access, at the microstructure scale, to the microscopic strain fields and the spatiotemporal distributions of the internal variables as well as the damage evolution in the polymer matrix and the reinforcement (yarns).

In this paper, 3D numerical simulations have been carried out to enhance the understanding of a flow over a passive control device composed of micro cylinder with, d/c = 1.34% placed in the vicinity of NACA0012 aerofoil wing, by means of γ–Reθt transition sensitive turbulence model meant to predict the separation induced by transition achieved for aerofoils operating at moderate Reynolds number (Re = 4.45×105). Results show that the separation of the boundary layer has been eliminated by the passive static vortex generator at stall regime due to the injection of free-stream momentum to the boundary layer. The early transition to turbulent state overcomes the local flow deceleration of an adverse pressure gradient and remains sticked to the wall the boundary layer. Furthermore, the wing aerodynamic performance are improved as drag is reduced and lift is enhanced which is straight forward linked to the lift to drag ratio gain that varies from 22.68% to 134.17% at post stall angles of attack.

International audience; New methods in metal forming are rapidly developing and several forming processes are used to optimize manufacturing components and to reduce cost production. Single Point Incremental Forming (SPIF) is a metal sheet forming process used for rapid prototyping applications and small batch production. This work is dedicated to the investigation of the profile geometry and thickness evolution of a truncated pyramid. The influence of process parameters during a SPIF process is also studied. A numerical response surface methodology with a Design of Experiments (DOE) is used to improve the thickness reduction and the effects of the springback. A set of 16 tests are performed by varying four parameters: tool diameter, forming angle, sheet thickness, and tool path. The Gurson-Tvergaard-Needleman (GTN) damage model is used to analyze the damage evolution during material deformation. It is found that the model can effectively predict the geometrical profile and

International audience; This paper deals with the adaptation and implementation of an adaptive direct torque control for the five-leg inverter-dual induction machine drive. The expectations are to take advantage of the direct control benefits, which are: sensorless, ease of implementation, and robustness against parameters variation. The application focuses on an electric vehicle with two driving wheels. For this, both induction motors coupled to the driving wheel are fed through a five-leg power inverter. For that purpose, the structure of this vehicle requires an electric differential, which allows maintaining the stability of the vehicle and especially during cornering. For this, the proposed direct control can ensure the separate control and distribute the required torques to the induction motors. Experiments and simulations are carried out to show that the developed independent control of five-leg inverter is effective and provides a simple configuration with good performance in terms of speed and torque responses.

Hidden Markov fields (HMFs) have been successfully used in many areas to take spatial information into account. In such models, the hidden process of interest X is a Markov field, that is to be estimated from an observable process Y. The possibility of such estimation is due to the fact that the conditional distribution of the hidden process with respect to the observed one remains Markovian. The latter property remains valid when the pairwise process ( X , Y ) is Markov and such models, called pairwise Markov fields (PMFs), have been shown to offer larger modeling capabilities while exhibiting similar processing cost. Further extensions lead to a family of more general models called triplet Markov fields (TMFs) in which the triplet ( U , X , Y ) is Markov where U is an underlying process that may have different meanings according to the application. A link has also been established between these models and the theory of evidence, opening new possibilities of achieving Dempster-Shafer fusion in Markov fields context. The aim of this paper is to propose a unifying general formalism allowing all conventional modeling and processing possibilities regarding information imprecision, sensor unreliability and data fusion in Markov fields context. The generality of the proposed formalism is shown theoretically through some illustrative examples dealing with image segmentation, and experimentally on hand-drawn and SAR images. We propose an original formalism unifying a large family of Markov fields.The proposed family of models is closed with respect to DS fusion rule.Our modeling handles information imprecision, sensor unreliability and data fusion.Dempster-Shafer fusion is performed by simply adding the corresponding Markov energies.A particular model from the new family is applied to image segmentation.

International audience; This paper proposes Adaptive Genetic Algorithms Guided by structural knowledges coming from decomposition methods, for solving PCSPs. The family of algorithms called AGAGD_x_y is designed to be doubly generic, meaning that any decomposition method and different heuristics for the genetic operators can be considered. To validate the approach, the decomposition algorithm due to Newman was used and several crossover operators based on structural knowledge such as the cluster, separator and the cut were tested. The experimental results obtained on the most challenging Minimum Interference-FAP problems of CALMA instances are very promising and lead to interesting perspectives to be explored in the future.

IF=0.888; International audience; This article is mainly motivated by the growing needs for highly resolved measurements forwall-bounded turbulent flows and aims to proposes a spatial correction coefficient in order toincrease the wall-shear stress sensors accuracy. As it well known for the hot wire anemometry, thefluctuating streamwise velocity measurement attenuation is mainly due to the spatial resolution andthe frequency response of the sensing element. The present work agrees well with this conclusionand expands it to the wall-shear stress fluctuations measurements using electrochemical sensors andsuggested a correction method based on the spanwise correlation coefficient to take into accountthe spatial filtering effects on unresolved wall-shear stress measurements due to too large sensorspanwise size