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This work investigates the identification of reduced-order state-space models from aeroelastic simulations of the interaction of a built-in structural finite element model and a linear aerodynamic model using unsteady potential theory. The objective is to propose and compare different new frequency-based identification methods operating on frequency response associated to the inputs and outputs of interest. The first methods considered are the Loewner interpolation method and a subspace algorithm. Subsequently, the paper introduces the possibility to apply stability constraints and to impose a certain number of poles estimated beforehand by the [Formula: see text] method in order to make the identified models closer to the true aeroelastic physics. To achieve this goal, new dedicated techniques are developed and subsequently validated on data generated by random state-space models of various orders, and on aeroelastic data obtained from structural and aerodynamic aircraft models.

International audience; Background and aims: A single hepatitis B virus (HBV) particle is sufficient to establish chronic infection of the liver after intravenous injection, suggesting that the virus targets hepatocytes via a highly efficient transport pathway. We therefore investigated whether HBV utilizes a physiological liver-directed pathway that supports specific host-cell targeting in vivo.Methods: We established an ex vivo system of perfused human liver tissue that recapitulates the liver physiology to investigate HBV liver targeting. This model allowed us to investigate virus-host cell interactions in a cellular microenvironment mimicking the in vivo situation. Results: HBV was rapidly sequestered by liver macrophages within one hour after a virus pulse, but was detected in hepatocytes only after 16 hours. We found that HBV associates with lipoproteins. Electron- and immunofluorescence microscopy corroborated a co-localization in recycling endosomes within peripheral and liver macrophages. Importantly, recycling endosomes accumulated HBV and cholesterol, followed by transport of HBV back to the cell surface along the cholesterol efflux pathway. To reach hepatocytes as final target cells, HBV was able to utilise the hepatocyte-directed cholesterol transport machinery of macrophages.Conclusions: Our results propose that HBV by binding to liver targeted lipoproteins and utilizing the reverse cholesterol transport pathway of macrophages hijacks the physiological lipid transport pathways to the liver to most efficiently reach its target organ. This may involve trans-infection of liver macrophages and result in deposition of HBV in the perisinusoidal space from where HBV can bind its receptor on hepatocytes

This work concerns the problem of gust load alleviation of a flexible aircraft by focusing on Airbus’s XRF1 aircraft concept, with a fully actuated wing. The aircraft is equipped with a lidar senso...

Liver-generated plasma Apolipoprotein E (ApoE)-containing lipoproteins (LPs) (ApoE-LPs) play central roles in lipid transport and metabolism. Perturbations of ApoE can result in several metabolic disorders and ApoE genotypes have been associated with multiple diseases. ApoE is synthesized at the endoplasmic reticulum and transported to the Golgi apparatus for LP assembly; however, ApoE-LPs transport from there to the plasma membrane is largely unknown. Here, we established an integrative imaging approach based on a fully functional fluorescently tagged ApoE. We found that ApoE-LPs accumulate in CD63-positive endosomes of hepatocytes. In addition, we observed the co-egress of ApoE-LPs and extracellular vesicles (EVs) along the late endosomal trafficking route. Moreover, complexes of ApoE-LPs and CD63-positive EVs were found to be transmitted from cell to cell. Given the important role of ApoE in viral infections, we studied the hepatitis C virus (HCV) and found that the viral replicase protein NS5A is enriched in ApoE-containing intraluminal vesicles. Interaction between NS5A and ApoE is required for the efficient release of EVs containing viral RNA. These vesicles are transported along the endosomal ApoE egress pathway. Taken together, our data argue for endosomal egress and transmission of hepatic ApoE-LPs, a pathway that is hijacked by HCV. Given the more general role of EV-mediated cell-to-cell communication, these insights provide new starting points for research into the pathophysiology of ApoE-related metabolic and infection-related disorders.Author SummaryThe post-Golgi egress pathway of hepatocyte-derived ApoE-containing lipoproteins (ApoE-LPs) is largely unknown. By using integrative imaging analyses, we show that ApoE-LPs are enriched in CD63-positive endosomes suggesting that these endosomes might be a central hub for the storage of ApoE-LPs from which they are released into the circulation. In addition, we provide evidence for the co-egress of ApoE-LPs with extracellular vesicles (EVs) along the late endosomal route and their transfer from cell to cell. This pathway is hijacked by the hepatitis C virus that induces the production of ApoE-associated EVs containing viral RNA. Given the important role of ApoE in multiple metabolic, degenerative and infectious diseases, and the role of EVs in cell-to-cell communication, these results provide important information how perturbations of ApoE might contribute to various pathophysiologies.

The hepatitis C virus (HCV) life cycle is highly regulated and characterized by a step-wise succession of interactions between viral and host cell proteins resulting in the assembly of macromolecular complexes, which catalyse genome replication and/or virus production. Non-structural (NS) protein 3, comprising a protease and a helicase domain, is involved in orchestrating these processes by undergoing protein interactions in a temporal fashion. Recently, we identified a multifunctional NS3 protease surface patch promoting pivotal protein-protein interactions required for early steps of the HCV life cycle, including NS3-mediated NS2 protease activation and interactions required for replicase assembly. In this work, we extend this knowledge by identifying further NS3 surface determinants important for NS5A hyperphosphorylation, replicase assembly or virion morphogenesis, which map to protease and helicase domain and form a contiguous NS3 surface area. Functional interrogation led to the identification of phylogenetically conserved amino acid positions exerting a critical function in virion production without affecting RNA replication. These findings illustrate that NS3 uses a multipurpose protein surface to orchestrate the step-wise assembly of functionally distinct multiprotein complexes. Taken together, our data provide a basis to dissect the temporal formation of viral multiprotein complexes required for the individual steps of the HCV life cycle.

International audience; Because our civilization has relied on pesticides to fight weeds, insects, and diseases since antiquity, the use of these chemicals has become natural and exclusive. Unfortunately, the use of pesticides has progressively had alarming effects on water quality, biodiversity, and humanhealth. This paper proposes to improve farming practices by replacing pesticides with a laser-based robotic approach. This study focused on the neutralization of aphids, as they are among the most harmful pests for crops and complex to control. With the help of deep learning, we developeda mobile robot that spans crop rows, locates aphids, and neutralizes them with laser beams. We have built a prototype with the sole purpose of validating the localization-neutralization loop on a single seedling row. The experiments performed in our laboratory demonstrate the feasibility ofdetecting different lines of aphids (50% detected at 3 cm/s) and of neutralizing them (90% mortality) without impacting the growth of their host plants. The results are encouraging since aphids are one of the most challenging crop pests to eradicate. However, enhancements in detection and mainly intargeting are necessary to be useful in a real farming context. Moreover, robustness regarding field conditions should be evaluated.

International audience; The advent of telerobotic systems has revolutionized various aspects of the industry and human life. This technology is designed to augment human sensorimotor capabilities to extend them beyond natural competence. Classic examples are space and underwater applications when distance and access are the two major physical barriers to be combated with this technology. In modern examples, telerobotic systems have been used in several clinical applications, including teleoperated surgery and telerehabilitation. In this regard, there has been a significant amount of research and development due to the major benefits in terms of medical outcomes. Recently telerobotic systems are combined with advanced artificial intelligence modules to better share the agency with the operator and open new doors of medical automation. In this review paper, we have provided a comprehensive analysis of the literature considering various topologies of telerobotic systems in the medical domain while shedding light on different levels of autonomy for this technology, starting from direct control, going up to command-tracking autonomous telerobots. Existing challenges, including instrumentation, transparency, autonomy, stochastic communication delays, and stability, in addition to the current direction of research related to benefit in telemedicine and medical automation, and future vision of this technology, are discussed in this review paper

International audience; Hand gesture recognition is a promising research area often used in applications of human–computer interactions in the medical field. In this paper, we present a novel approach to differentiate gestures based on an arc-length parametrization and a curvature analysis of 3D trajectories. This new method called dynamic arc length warping (DALW) can outperform classic multi dimensional-dynamic time warping (MD-DTW) algorithm as it is invariant to sensor location and more tolerant to temporal distortions. Experimental validation of the algorithm is presented using different gestures and sensors in biomedical applications: an exoskeleton apparatus, surgical gestures captured by an instrumented laparoscopic device and finally, a birth simulator with an instrumented forceps. A basic perceptron multilayer neural network was implemented in order to perform the classification. Results involve an average increase of 7.14% in the classification rates by using DALW distance, compared to the classical MD-DTW.

This paper presents a state-averaged model and the design of nonlinear observers for an on/off pneumatic actuator. The actuator is composed of two chambers and four on/off solenoid valves. The elaborated state-averaged model has the advantage of using only one continuous input instead of four binary inputs. Based on this new model, a high-gain observer and a sliding-mode observer are designed using the actuator position and the pressure measurements in one of the chambers. Finally, their closed-loop performance is verified and compared on an experimental benchmark.

Double membrane vesicles (DMVs) serve as replication organelles of plus-strand RNA viruses such as hepatitis C virus (HCV) and SARS-CoV-2. Viral DMVs are morphologically analogous to DMVs formed during autophagy, but lipids driving their biogenesis are largely unknown. Here we show that production of the lipid phosphatidic acid (PA) by acylglycerolphosphate acyltransferase (AGPAT) 1 and 2 in the ER is important for DMV biogenesis in viral replication and autophagy. Using DMVs in HCV-replicating cells as model, we found that AGPATs are recruited to and critically contribute to HCV and SARS-CoV-2 replication and proper DMV formation. An intracellular PA sensor accumulated at viral DMV formation sites, consistent with elevated levels of PA in fractions of purified DMVs analyzed by lipidomics. Apart from AGPATs, PA is generated by alternative pathways and their pharmacological inhibition also impaired HCV and SARS-CoV-2 replication as well as formation of autophagosome-like DMVs. These data identify PA as host cell lipid involved in proper replication organelle formation by HCV and SARS-CoV-2, two phylogenetically disparate viruses causing very different diseases, i.e. chronic liver disease and COVID-19, respectively. Host-targeting therapy aiming at PA synthesis pathways might be suitable to attenuate replication of these viruses., Double membrane vesicles (DMV) are used as replication organelles by several RNA viruses. Applying proteomics and lipidomics, Tabata and Prasad et al. find that two cellular acyltransferases (AGPAT1/2), responsible for synthesis of phosphatidic acid, play a role in the DMV-biogenesis of HCV and SARS-CoV-2, highlighting a common biogenesis mechanism for evolutionary distant positive-strand RNA viruses.

Contains fulltext : 226711.pdf (Publisher’s version ) (Open Access) Following tool-use, the kinematics of free-hand movements are altered. This modified kinematic pattern has been taken as a behavioral hallmark of the modification induced by tool-use on the effector representation. Proprioceptive inputs appear central in updating the estimated effector state. Here we questioned whether online proprioceptive modality that is accessed in real time, or offline, memory-based, proprioception is responsible for this update. Since normal aging affects offline proprioception only, we examined a group of 60 year-old adults for proprioceptive acuity and movement's kinematics when grasping an object before and after tool-use. As a control, participants performed the same movements with a weight - equivalent to the tool - weight-attached to their wrist. Despite hampered offline proprioceptive acuity, 60 year-old participants exhibited the typical kinematic signature of tool incorporation: Namely, the latency of transport components peaks was longer and their amplitude reduced after tool-use. Instead, we observed no kinematic modifications in the control condition. In addition, online proprioception acuity correlated with tool incorporation, as indexed by the amount of kinematics changes observed after tool-use. Altogether, these findings point to the prominent role played by online proprioception in updating the body estimate for the motor control of tools. 9 p.

International audience; A semi-autonomous robotic system dedicated to road and train bridge inspection is presented in this paper. So far, bridge inspections have been performed manually by workers who either climb and rappel or use so-called mobile negative cherry pickers or specific mobile assemblies. This is a dangerous and tedious task which must be carried out during night time or when the traffic on the bridge is stopped, for safety reasons. The installation of mobile assemblies is costly, time consuming and they become not compliant with recent structures. Moreover, manual inspections require counting, measuring, locating and taking pictures of small cracks. The quality of these manual operations depends not only on the experience but also on the level of fatigue of the workers. The robotic inspection system proposed in this paper consists of three main components: a customized truck, a mobile robotic mechanism which takes pictures of the entire area of interest, and a software which automatically associates these pictures with the CAD model of the bridge.Afterwards at office, users browse the pictures of the surfaces of the bridge with the help of the CAD software and a dedicated plugin to detect, measure and comment the bridge defects to process later. The result is summed up into a report generated by the software. The requirements and the mechanical design of this system are described and an overview of the inspections realized so far with it is provided.

A hydrological impact analysis concerns the study of the consequences of certain scenarios on one or more variables or fluxes in the hydrological cycle. In such an exercise, discharge is often considered, as floods originating from extremely high discharges often cause damage. Investigating the impact of extreme discharges generally requires long time series of precipitation and evapotranspiration to be used to force a rainfall-runoff model. However, such kinds of data may not be available and one should resort to stochastically generated time series, even though the impact of using such data on the overall discharge, and especially on the extreme discharge events, is not well studied. In this paper, stochastically generated rainfall and corresponding evapotranspiration time series, generated by means of vine copulas, are used to force a simple conceptual hydrological model. The results obtained are comparable to the modelled discharge using observed forcing data. Yet, uncertainties in the modelled discharge increase with an increasing number of stochastically generated time series used. Notwithstanding this finding, it can be concluded that using a coupled stochastic rainfall–evapotranspiration model has great potential for hydrological impact analysis.

This paper introduces preliminary works on building an experimental end-user evaluation for dual-user haptic systems for hands-on training. Such systems bring together the advantages of haptic computer-based training systems and those of supervised training where an expert trainer actively helps in the learning process. The first results mainly permitted to highlight several technical and organizational issues to overcome in a close future. The objective of this project is to test other architectures such as those listed in the state-of-the-art section, to provide comparative conclusions about the pros and cons of each one.

International audience; Touch is one of the most important sensory inputs during the performance of surgery. However, the literature on kinesthetic and tactile feedback both called haptics in surgical training remains rudimentary. This rudimentary knowledge is partial since that haptic feedback is difficult to describe, as well as record and playback. This chapter aims at focusing on the use of haptics in the training of medical staff and also as a complementary tool for robotized and remote procedures. It provides an overview of the various available technologies to perform haptic feedback and details on how haptic guidance can enhance surgical skill acquisition. A critical review of available haptic interfaces vis-a-vis medical interventions to be performed is provided. The chapter ends with an illustration merging the advantages of usual supervised hands-on training and the ones offered by computer-based training: dual-user training simulators.

International audience; Haptic simulators are used in many education domains to improve hands-on training performance. Many of these simulators are used in the medical domain, where it is particularly important to be trained, guided by an expert. However, the majority of haptic hands-on training devices are usable by only one user at the same time, either the trainer or the trainee. Dual-user approaches have enhanced this situation by allowing both trainer and trainee to use the same simulator to introduce guided training into the simulation. In this paper, we introduce a multi-trainee architecture that expands further a former dual-user hands-on haptic training solution designed according to an energetic approach. This system will permit several trainees to be involved in the same simulation at the same time, guided by a single trainer. It paves the way to the multi-trainee hands-on training on haptic simulators.

The classification of human hand gestures has gained widespread recognition as a natural and powerful way to interact intuitively and efficiently with computers. Specifically, this approach has facilitated the development of a number of important applications in the medical training field, specially as a way to objectively evaluate surgical tasks of novices compared to an expert surgeon. In this paper, 3D medical gestures, acquired by an instrumented laparoscopic forceps, were classified using Long Short Term Memory (LSTM) recurrent neural networks (RNN). Recognition results are based on gesture dynamics and a comparison of gesture trajectories between novices to an expert motion are presented. Using LSTM RNN, we were able to achieve a recognition rate of 99.1%.

Simulators have been traditionally used for centuries during medical gestures training. Nowadays, mechatronic technologies have opened the way to more evolved solutions enabling objective assessment and dedicated pedagogic scenarios. Trainees can now practice in virtual environments representing various kind of patient and body parts including physio-pathologies issues. Gestures, to be mastered, vary according to each medical specialty (e.g., ultrasound probe orientations, or forceps installation during assisted delivery). Hence, medical students need kinesthetic feedback in order to significantly improve their learning capabilities. Gesture simulators require haptic devices with variable stiffness actuators. Existing solutions do not always fit the requirements because of their significant size. Contrary to electric actuators, pneumatic technology is low-cost, available off-the-shelf and offers a better mass&ndash, power ratio. However, it presents two main drawbacks: nonlinear dynamics and need for a compressed air supply. During the last decade, we have developed several haptic solutions based on pneumatic actuation (e.g., birth simulator, epidural needle insertion simulator) and, recently, in a joint venture with Prisme laboratory, a pneumatic probe master device for remote ultrasonography. This paper recalls literature scientific approaches on pneumatic actuation developed in the medical context and illustrated with the aforementioned applications to highlight the benefits.

Composites of carbon nanotubes – titanate nanotubes (MWNTs/ TNTs) – were successfully synthesized by the hydrothermal reaction process. The morphology of the MWNTs/TNTs composites was observed by transmission electron microscopy. Fourier transform infrared spectroscopy was used to characterize the molecular interactions between TNTs and MWNTs in the composites. The X-ray diffraction of TNTs and MWNTs/TNTs composites exhibited the existence of titanate phase (100), (102), (020) and (422). The charge recombination of MWNTs/TNTs composites was examined by photoluminescence spectrum. The photocatalytic activity of TNTs and MWNTs/TNTs composites was evaluated on the basis of the model oxidation reaction of H2S.

The analysis of some properties for the equilibria of switched dynamic systems is addressed. In particular, the geometric properties of the equilibrium region in state space and the algebraic properties of the equations defining it are studied. Based on fundamental results from algebraic geometry the equilibria properties of switched dynamic systems is analyzed. This alternative approach allows to obtain information about the set of equilibrium points without explicitly computing it. This study is developed for three different formulations of switched dynamic systems, revealing some interesting algebraic and geometric relations in their corresponding equilibria. Some examples, including the case of a power converter, are presented for illustration purposes.

SUMMARYThis paper introduces a dual-user training system whose design is based on an energetic approach. This kind of system is useful for supervised hands-on training where a trainer interacts with a trainee through two haptic devices, in order to practice on a manual task performed on a virtual or teleoperated robot (e.g., for an Minimally Invasive Surgery (MIS) task in a surgical context). This paper details the proof of stability of an Energy Shared Control (ESC) architecture we previously introduced for one degree of freedom (d.o.f.) devices. An extension to multiple degrees of freedom is proposed, along with an enhanced version of the Adaptive Authority Adjustment function. Experiments are carried out with 3 d.o.f. haptic devices in free motion as well as in contact contexts in order to show the relevance of this architecture.

International audience; The characterization and analysis of hand gestures are challenging tasks with an important number of applications in human–computer interaction, machine vision and control, and medical gesture recognition. Specifically, several researchers have tried to develop objective evaluation methods of surgical skills for medical training. As a result, the adequate selection and extraction of similarities and differences between experts and novices have become an important challenge in this area. In particular, some of these works have shown that human movements performed during surgery can be described as a sequence of constant affine-speed trajectories. In this article, we will show that affine speed can be used to segment medical hand movements and present how the mechanical energy computed in the segment is analyzed to compare surgical skills. The position and orientation of the instrument end effectors are determined by six video photographic cameras. In addition, two laparoscopic instruments are capable of measuring simultaneously the forces and torques applied to the tool. Finally, we will report the results of these experiments and present a correlation between the mechanical energy values, dissipated during a procedure, and the surgical skills.

International audience; This paper presents a bond graph (BG) model and a physical structural analysis of an intermediary cooling system of a power plant. The main goal is to extend the techniques already in use for the physical structural analysis of mechatronic systems to perform static analysis and diagnosis on physical models in order to state whether they are well-posed and suitable for each step of the system's lifecycle (from its design to its operation). If a problem for modeling, for simulating or for solving the given engineering question is detected, the analysis shall localize the problem in the model and give the physical interpretation of the error. The objective is not to be able to diagnose all possible physical errors, but to add another type of analysis in order to improve error detection before compiling and running a model.

International audience; The aim of this study is to determine if navigation movements, used in surgical training, follow a particular power law which describes the relationship between the hand trajectory's curvature, torsion, and speed. Based on this approach, this study proposes the affine velocity as an appropriate classification feature to solve the surgical movement recognition problem. Eight subjects with different surgical experience were involved in the experiments. They were asked to do two kinds of movements that involve depth perception skills with their right arm. Using six video cameras and an instrumented laparoscope, the 3D trajectory of the end effector was recorded for each participant. A power law was used to fit the data sets and the exponents that relate the torsion, curvature, and speed were calculated. The exponents involved and the affine velocity for each trajectory were then computed, using a multi-variable linear regression, and compared between participants. It is shown that fitting residual follows a normal distribution indicating no regression biases. Finally, it is presented that an affine velocity analysis could be able to classify between both trajectories showing a correlation with the surgical skills and a clear difference for people with some surgical training.

International audience; This paper introduces the development of exercises to be embedded in a lightweight laparoscopic haptic simulator to help surgeons starting their training to Minimal Invasive Surgery (MIS) gestures. These exercises were created by observing professionals in operation rooms andby isolating key gestures, which have been combined to create desired trajectories with a slow learning curve. These exercises combine memory,new gestures, new environments and new visual feedback so that the trainees’ cognitive load remains low. This favors an effective training.Hence, the simulator displays a simple 3D virtual environment in order to focus on the gestures and trajectories, performed on an haptic deviceby means of real MIS tool handles. Its ludic dimension, which make it a Serious Game, should help users to make progress in their first gesturetraining in order to continue on more evolved medical simulators. This paper introduces the software architecture analysis and the methods used for creating the exercises.

International audience; A hybrid Lyapunov control for a flying capacitor multicellular converter is presented. This control law is based on the Port-Hamiltonian (PH) formalism of power converters and allows to enhance load current quality and reduce switching losses. The proposed control is applied to a three-cell multicellular converter. A procedure for selecting the best weighting parameters in the control law according to a performance criterion is presented. The simulation and experimental results indicate the stability of the control for changes in the reference signals. A comparison with a different Lyapunov control technique shows the performance of the proposed solution and the advantage of such a strategy in order to reduce the switching losses.

International audience; Minimally Invasive Surgery (MIS) has become widespread as an important surgical technique due to its advantages related to pain relief and short recovery time periods. However, this approach implies the acquisition of special surgical skills, which represents a challenge in the objective assessment of surgical gestures. In this way, several studies shown that kinematics and kinetic analysis of hand movement is a valuable assessment tool of basic surgical skills in MIS. In addition, recent researches proved that human motion performed during surgery can be described as a sequence of constant affine velocity movements. In this paper, we present a novel method to classify gestures based on an affine velocity analysis of 3D motion and an implementation of the Dynamic Time Warping algorithm. In particular, affine velocity calculation correlates kinematics and geometrical variables such as curvature, torsion, and euclidean velocity, reducing the dimension of the conventional 3D problem. In this way, using the simplicity of dynamic time warping algorithm allows us to perform an accurate classification, easier to implement and understand. Experimental validation of the algorithm is presented based on the position and orientation data of a laparoscope instrument, determiMinimally Invasive Surgery (MIS) has become widespread as an important surgical technique due to its advantages related to pain relief and short recovery time periods. However, this approach implies the acquisition of special surgical skills, which represents a challenge in the objective assessment of surgical gestures. In this way, several studies shown that kinematics and kinetic analysis of hand movement is a valuable assessment tool of basic surgical skills in MIS. In addition, recent researches proved that human motion performed during surgery can be described as a sequence of constant affine velocity movements. In this paper, we present a novel method to classify gestures based on an affine velocity analysis of 3D motion and an implementation of the Dynamic Time Warping algorithm. In particular, affine velocity calculation correlates kinematics and geometrical variables such as curvature, torsion, and euclidean velocity, reducing the dimension of the conventional 3D problem. In this way, using the simplicity of dynamic time warping algorithm allows us to perform an accurate classification, easier to implement and understand. Experimental validation of the algorithm is presented based on the position and orientation data of a laparoscope instrument, determined by six cameras. Results show the advantages of the proposed method compared to conventional Multidimensional Dynamic Time Warping to classify surgical gestures in MIS.ned by six cameras. Results show the advantages of the proposed method compared to conventional Multidimensional Dynamic Time Warping to classify surgical gestures in MIS.

International audience; This paper proposes a general approach to design a feedback control law for DC/DC power converters. These last ones can be modeled as switched port-Hamiltonian systems. Based on Lyapunov theory, a candidate Lyapunov function representing the energy of the system is proposed. Advantages of the resulting control law include ease of design and implementation in real time applications. The proposed control is applied in simulation for Buck, Buck-Boost, SEPIC and Ćuk converters. A comparison with a PWM state feedback control law is given for the last two converters.

International audience; The only way to insure a good satellite communication data rate on a moving vehicle is to maintain an antenna bore-sight in the satellite direction. To do so, the antenna is mounted on an Antenna Positioning Systems(APS). The APS is a motorized gimbals that make the antenna move in order to maintain a proper pointing, regardless the vehicle movements. This kind of satellite communication is called SATCOM On The Move (SOTM). In this paper, an hybrid pointing strategy, using least squares identification and gyroscopes is proposed and tested through realistic simulation. The main difference with other strategies is that the scanning is made using only the motion due to measurement noise and gyroscope drift, making unnecessary the introduction of a pointing dither on purpose, as it is usually done. Such a dither is referred as self-induced dither. The main advantage of this strategy is its robustness with respect to non-linearities due to mechanical faults since no precise dither trajectory has to be followed. Another benefit is that attitude measurements are not used during tracking, making the strategy proposed especially interesting for low cost applications.

Titanium dioxide (TiO2) nanotubes were synthesized via one-step dynamic hydrothermal process from commercial TiO2 powder. The effects of NaOH concentration, reaction time, reaction temperature, stirring process and washing on the morphology, and the exchange ions of the nanotubes were investigated. The morphology of the nanotubes was characterized in detail with transmission electron microscopy and scanning electron microscope. In the dynamic hydrothermal process, stirring can reduce the reaction time of transformation from particles to nanotubes. The nanotubes were formed when the expected reaction temperature reached to 130 °C. Energy dispersive X-ray analysis was used to determine the exchange of sodium ions and protons in washing process. The Na+ ions attached in the nanotubes were removed completely by HCl aqueous solution and deionized water treatments. X-ray diffraction patterns showed the titanate phase of the as-synthesized sample and anatase phase of TiO2 nanotubes after calcination process at 400 °C for 2 h.

International audience; For a pneumatic teleoperation system with on/off solenoid valves, sliding-mode control laws for position and force, ensuring low switching (open/close) activity of the valves are developed. Since each pneumatic actuator has two pneumatic chambers with a total of four on/off valves, sixteen possible combinations ("operating modes") for the valves' on/off positions exist, but only seven of which are both functional and unique. While previous work has focused on 3-mode sliding-based position control of one pneumatic actuator, this paper develops the seven-mode sliding-based bilateral control of a teleoperation system comprising a pair of pneumatic actuators. The proposed bilateral sliding control schemes are experimentally validated on a pair of actuators utilizing position-position and force-position teleoperation architectures. The results demonstrate that leveraging the additional modes of operation leads to more efficient and smoother control of the pneumatic teleoperation system. It was found that viscous friction forces were crippling haptic feedback in the position-position architecture. Through the use of force sensors, the force-position architecture was able to compensate for the heavy viscous friction forces.

Of all natural disasters, the economic and environmental consequences of droughts are among the highest because of their longevity and widespread spatial extent. Because of their extreme behaviour, studying droughts generally requires long time series of historical climate data. Rainfall is a very important variable for calculating drought statistics, for quantifying historical droughts or for assessing the impact on other hydrological (e.g. water stage in rivers) or agricultural (e.g. irrigation requirements) variables. Unfortunately, time series of historical observations are often too short for such assessments. To circumvent this, one may rely on the synthetic rainfall time series from stochastic point process rainfall models, such as Bartlett–Lewis models. The present study investigates whether drought statistics are preserved when simulating rainfall with Bartlett–Lewis models. Therefore, a 105 yr 10 min rainfall time series obtained at Uccle, Belgium is used as a test case. First, drought events were identified on the basis of the Effective Drought Index (EDI), and each event was characterized by two variables, i.e. drought duration (D) and drought severity (S). As both parameters are interdependent, a multivariate distribution function, which makes use of a copula, was fitted. Based on the copula, four types of drought return periods are calculated for observed as well as simulated droughts and are used to evaluate the ability of the rainfall models to simulate drought events with the appropriate characteristics. Overall, all Bartlett–Lewis model types studied fail to preserve extreme drought statistics, which is attributed to the model structure and to the model stationarity caused by maintaining the same parameter set during the whole simulation period.

The efficacy of a potassium 12-phosphotungstate (KPW) catalyst in the synthesis of methyl 2-keto-L-gulonat from 2-keto-L-gulonic acid (2-KLGA) and methanol is investigated. The KPW catalyst gives high yields in short reaction times. The present procedure represents a clean, efficient, practical, simple, mild, time-saving and eco-friendly method for the synthesis of methyl 2-keto-L-gulonat. The KPW catalyst is found to be a truly heterogeneous catalyst, highly efficient and reusable in the synthesis of methyl 2-keto-L-gulonat.

This paper deals with a new simulation tool for the improvement of multi-robot pick & place applications performance combining behavioral simulation of multiple robots and products flows. A novelty of the proposed work is to take into account in the simulation not only the scheduling rules of each robot, but also the robots collaborative aspect to ensure the desired overall performance for a given task. The transition from simulation to implementation of pick & place strategies is also an issue tackled in this paper. By using a typical example consisting of comparing techniques to optimize the workflow, the utility of the simulation tool is proven. First experimental results validate the simulation results.

International audience; In order to increase the realism of medical simulators, haptic interfaces could be used to simulate the patient’s body behavior. It is especially interesting to reproduce the stiffness of different soft tissues with corresponding haptic behaviors. In this paper, two control laws, impedance control and back-stepping associated with a closed-loop stiffness tuning, are introduced and applied to a pneumatic actuator. Both controllers have been obtained by using the A-T transform which is suitable to model the behavior of a pneumatic system, in a strict-feedback form. Both control laws allow to tune the system stiffness. A comparison of their performances is presented, based on experimental results.

International audience; This paper presents an averaged model and nonlinear observer for an on/off pneumatic actuator. The actuator is composed of two chambers and four on/off solenoid valves. The proposed averaged model has the advantage of using only one continuous input instead of four binary inputs. Based on this new model, a sliding mode observer is designed using the piston position and the pressure measurements in one of the chambers in order to estimate the piston velocity and the pressure in the other chamber. The observation errors converge towards zero in finite time and the performance of this observer is validated in closed loop on an experimental benchmark.

International audience; This paper presents a Bond Graph (BG) modellingapproach to add and exploit on existing Modelica mod-els some information on the energy structure of thesystems. The developed models in the ThermosysProlibrary (Modelica-based) are already validated againstthe experimental data in previous works. A plate heatexchanger (PHE), which is equipment for nuclear powerplants, is considered as a case study in this paper.Simulation results of the BG model for the counterflowPHE are compared with simulation results of the testedModelica model. Comparisons show good agreementbetween both model results.

International audience; In this paper, a presentation of Tchebychev polynomials’ properties and a formulation derived using these polynomials are performed. The identification method presented consists in applying a linear transformation to the set of equations of the process. For this, the mathematical operator used is based on a decomposition of the signal in a basis of orthogonal polynomials. We show that this projection acts as a bandpass filter, so that only one operation is required for the data preprocessing before the identification, namely the choice of the Chebyshev polynomials basis size. An experimental closed-loop identification of a 2-axis robot with this method is performed in a final section. The results are compared and analyzed with other techniques used in robotics.; Dans cet article, une présentation des propriétés des polynômes de Tchebychev et une formulation dérivée utilisant ces polynômes sont effectuées. La méthode d'identification présentée consiste à appliquer une transformation linéaire sur le système d'équations qui régit le processus. Pour cela, l'opérateur mathématique utilisé s'appuie sur une décomposition du signal dans une base formée de polynômes orthogonaux. Nous montrons que cette projection se comporte comme un filtre passe-bande, de telle sorte qu'une seule opération est nécessaire pour le pré-traitement des données avant le processus d'identification, à savoir choisir la dimension de la base des polynômes Tchebychev. Une identification expérimentale en boucle fermée d'un robot à 2 axes avec cette méthode est effectuée dans une dernière partie. Les résultats obtenus sont comparés et analysés avec d'autres techniques utilisées en robotique.

Texte complet : http://www.sciencedirect.com/science?_ob=MiamiImageURL&_cid=271236&_user=884697&_pii=S0301211511004994&_check=y&_origin=&_coverDate=02-Oct-2011&view=c&wchp=dGLzVlB-zSkzS&md5=43c5f8d46713c429e671e66dc2a8fc27/1-s2.0-S0301211511004994-main.pdf; International audience; Objective The aim of this study was to evaluate whether forceps training on a birth simulator allows obstetricians to improve forceps blade placement. Study design Analysis was based on 600 forceps blade placements performed by ten trainees on a simulator. The trajectories used by the trainees were assessed using reference spheres that reflected an optimal bimalar placement. Three definitions of success were used: small-sphere success, medium-sphere success and large-sphere success were respectively defined by the forceps blade tip being within 5, 10 or 15 mm of the center of the sphere (the small-sphere being nested within the medium-sphere and the small and medium being nested within the large-sphere). Wilcoxon paired analysis was performed to compare the first (50 trajectories) and final (50 trajectories) sets of five forceps placements. Graphical representation and linear regression were used to visualize the learning process. Results 596 trajectories were available for analysis. During the last set of five forceps the success rate was respectively 28%, 72% and 86% for small-sphere, medium-sphere and large-sphere success with the right blade and 8%, 32% and 70% for the left blade. Wilcoxon analysis showed a highly significant improvement for all kinds of success in the right blade and for large-sphere success in the left blade. Linear regression slopes were significant. Using a projection, the theoretical numbers of placements needed to achieve a 100% success rate for small-sphere, medium-sphere and large-sphere were respectively 80, 45 and 35. Conclusion These results strongly suggest that performing forceps blade placement on birth simulator allows obstetricians to improve their skills.

National audience; Cet article présente une des fonctionnalités du simulateur d'accouchement BirthSIM : la simulation d'accouchement instrumental. Son objectif est de proposer une nouvelle méthode de formation aux novices obstétriciens pour compléter la formation traditionnelle en salle d'accouchement. En obstétrique il peut être nécessaire d'utiliser des forceps pour extraire le nouveau-né en cas d'urgence, or ces instruments nécessitent une certaine expérience pratique. Cet article présente donc l'approche retenue pour simuler la dynamique d'un accouchement sur le simulateur BirthSIM. Plusieurs procédures sont disponibles sur le simulateur BirthSIM et nous nous intéressons particulièrement à une procédure qui permet de simuler un accouchement instrumental difficile. Afin d'assurer le réalisme de l'extraction sur le simulateur BirthSIM, il est nécessaire de reproduire les différents efforts mis en jeu lors d'un accouchement. Pour cela nous avons retenu une loi de commande originale : un asservissement en position avec un gain variable afin de modifier la raideur du système. Les résultats présentés dans cet article soulignent le besoin des novices d'acquérir une certaine expérience avant de se former classiquement en salle d'accouchement.

International audience; This paper presents the control algorithm implanted on the childbirth simulator BirthSIMin order to provide training to novice obstetricians. The forceps extraction is an obstetric manipulation learned by experience. However, nowadays the training is mainly provided during real childbirths. This kind of training could lead to dramatic consequences due to the lack of experience of some operators. This paper explains the approach which has been used to simulate the dynamic process of a childbirth on the BirthSIM simulator. We especially focus on one procedure which reproduces a difficult instrumental delivery. The recorded tractive force to extract the fetus corresponds to the literature results which confirms the realism of the simulator. The novice results emphasize the need of a childbirth simulator in order to gain initial experience without any risks.

Adresse Internet du journal : http://www.sciencedirect.com/science/journal/15320464; International audience; This paper focuses on the gesture analysis in order to compare two human gestures. The orientations and the positions of the gestures are both taken into account and the similarity rate between two gestures is calculated. In our case, the application is in obstetrics and the aim is to evaluate forceps blade placement. The method is based on the curvature analysis of the paths during the gesture. The 3-D position paths are expressed according to their cumulated chord length and the orientation paths in the quaternion unit space. These parameterizations lead to analyze data in space independently to time as requested by physicians. After filtering data in order to minimize sensor noises, the gestures are then compared by calculating the correlation between the position and the orientation curvatures of a novice gesture and an expert one. The results clearly show that novice skills in handling forceps increase in becoming smoother and closer to the reference placement. A childbirth simulator allows novices to acquire experience without any risks, however the training have to be completed with the extraction gesture evaluation and a compulsory training period in the delivery ward.

This report presents an averaged model and nonlinear observer for an on/off pneumatic actuator. The actuator is composed of two chambers and four on/off solenoid valves. The averaged model is elaborated which has the advantage of using only one continuous input instead of four binary inputs. Based on this new model, a sliding mode observer is designed using the piston's position and the pressure measurements in one of the chambers to estimate the piston velocity and the pressure in the other chamber. The finite time convergence of the observer is proven and its performance is verified in closed loop on an experimental benchmark.

Evapotranspiration is an important process in the water cycle that represents a considerable amount of moisture lost to the atmosphere through evaporation from the soil and wet surfaces, and transpiration from plants. Therefore, several water management methods, such as irrigation scheduling and hydrological impact analysis, rely on an accurate estimation of evapotranspiration rates. Often, daily reference evapotranspiration is modelled based on the Penman, Priestleyâ Taylor or Hargraeves equation. However, each of these models requires extensive input data, such as daily mean temperature, wind speed, relative humidity and solar radiation. Yet, in design studies, such data may be unavailable and therefore, another approach may be needed that is based on stochastically generated time series. More specifically, when rainfall-runoff models are used, these evapotranspiration data need to be consistent with the accompanying (stochastically generated) precipitation time series data. In this paper, such an approach is presented in which the statistical dependence between evapotranspiration, precipitation and temperature is described by three- and four-dimensional vine copulas. Based on a case study of 72 years of evapotranspiration, temperature and precipitation data, observed in Uccle, Belgium, it is shown that canonical vine copulas (C-vines) perform very well in preserving the dependences between variables. ispartof: Stochastic Environmental Research and Risk Assessment vol:30 issue:8 pages:2197-2214 status: published

Nos remerciements à IEEE pour l'autorisation de mise à disposition du papier complet. © IEEE Copyright Notice : Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.; International audience; Today, medical simulators are increasingly gaining appeal in clinical settings. In obstetrics childbirth simulators provide a training and research tool for comparing various techniques that use obstetrical instruments or validating new methods. Especially in the case of difficult deliveries, the use of obstetrical instruments - such as forceps, spatulas, and vacuum extractors - has become essential. However, such instruments increase the risk of injury to both the mother and fetus. Only clinical experience acquired in the delivery room enables health professionals to reduce this risk. In this context, we have developed, in collaboration with researchers and physicians, a new type of instrumented forceps that offers new solutions for training obstetricians in the safe performance of forceps deliveries. This paper focuses on the design of this instrumented forceps, coupled with the BirthSIM simulator. This instrumented forceps allows to study its displacement inside the maternal pelvis. Methods for analyzing the operator repeatability and to compare forceps blade placements to a reference one are developed. The results highlight the need of teaching tools to adequately train novice obstetricians.