Direct and indirect methods to optimize the muscular force response to a pulse train of electrical stimulation

Recent force-fatigue mathematical models in biomechanics [7] allow to predict the muscular force response to functional electrical stimulation (FES) and leads to the optimal control problem of maximizing the force. The stimulations are Dirac pulses and the control parameters are the pulses amplitudes and times of application, the number of pulses is physically limited and the model leads to a sampled data control problem. The aim of this article is to present and compare two methods. The first method is a direct optimization scheme where a further refined numerical discretization is applied on the dynamics. The second method is an indirect scheme: first-order Pontryagin type necessary conditions are derived and used to compute the optimal sampling times

Estimation d'un procédé de cristallisation en batch

The aim of this work is the estimation of crystal size distribution (CSD) of batch and polymorphic crystallization processes. The CSD evolution is described by partial differential equation (PDE) which requires the use of discretization methods. On line identification was realized in order to perform a real time correction of model parameters. An interesting alternative to CSD's sensors is the use of observers. First, we applied tow observers in the case of growth size independent. After that, a Kalman-like observer was tested in the case of growth size dependent. The validation of identification and estimation of the CSD was done by simulation. The results were very interesting with regard to the luck of measurements and the huge number of variables to estimateL'objectif de ce travail est l'estimation de la distribution des tailles de cristaux (DTC) d'un procédé de cristallisation en batch ainsi qu'un procédé de cristallisation polymorphique. L'évolution de la DTC est décrite par une équation aux dérivées partielles (EDP) et nécessite l'utilisation de méthodes de discrétisation pour l'exploiter. Une identification en ligne a été réalisée en vue d'une correction en temps réel des paramètres du modèle. Une alternative aux différents capteurs pour la DTC est l'utilisation d'observateurs. Tout d'abord, nous avons appliqué deux types d'observateurs dans le cas d'une croissance identique pour toutes les tailles de cristaux. Ensuite, un observateur de type Kalman a été testé dans le cas d'une croissance dépendante de la taille des cristaux. La validation de l'identification et de l'estimation de la DTC a été effectuée par simulation. Ces résultats ont été très intéressants compte tenu du manque de mesures et du grand nombre d'états à estime

ESTIMATION OF CRYSTAL SIZE DISTRIBUTION OF A BATCH CRYSTALLIZATION PROCESS USING A GROWTH SIZE DEPENDENT MODEL

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Connection between singular arcs in optimal control using bridges.Physical occurence and Mathematical model

International audienceIn the time minimal control problem, singular arcs are omnipresent to determine the optimal solutions and leads to the well known turnpike phenomenon [1]. Very recently, this connection between singular arcs using a bang arc was shown to be relevant to saturate a single spin in Magnetic Resonance Imaging. Based on this example we propose a mathematical model to analyze such connection, which is called a bridge. This is applied to compute bridges in the optimization of chemical reaction networks using temperature control

A case study of optimal input-output system with sampled-data control: Ding et al. force and fatigue muscular control model

International audienceThe objective of this article is to make the analysis of the muscular force response to optimize electrical pulses train using Ding et al. force-fatigue model. A geometric analysis of the dynamics is provided and very preliminary results are presented in the frame of optimal control using a simplified input-output model. In parallel, to take into account the physical constraints of the problem, partial state observation and input restrictions, an optimized pulses train is computed with a model predictive control, where a non-linear observer is used to estimate the state-variables

Human Action Recognition with Skeleton and Infrared Fusion Model

International audienceSkeleton-based human action recognition conveys interesting information about the dynamics of a human body. In this work, we develop a method that uses a multi-stream model with connections between the parallel streams. This work is inspired by a state-of-the-art method called FUSIONCPA that merges different modalities: infrared input and skeleton input. Because we are interested in investigating improvements related to the skeleton-branch backbone, we used the Spatial-Temporal Graph Convolutional Networks (ST-GCN) model and an EfficientGCN attention module. We aim to provide improvements when capturing spatial and temporal features. In addition, we exploited a Graph Convolutional Network (GCN) implemented in the ST-GCN model to capture the graphic connectivity in skeletons. This paper reports interesting accuracy on a large-scale dataset (NTU-RGB+D 60), over 91% and 93% on respectively crosssubject, and cross-view benchmarks. This proposed model is lighter by 9 million training parameters compared with the model FUSION-CPA

Estimation d'un procédé de cristallisation en batch

L'objectif de ce travail est l'estimation de la distribution des tailles de cristaux (DTC) d'un procédé de cristallisation en batch ainsi qu'un procédé de cristallisation polymorphique. L'évolution de la DTC est décrite par une équation aux dérivées partielles (EDP) et nécessite l'utilisation de méthodes de discrétisation pour l'exploiter. Une identification en ligne a été réalisée en vue d'une correction en temps réel des paramètres du modèle. Une alternative aux différents capteurs pour la DTC est l'utilisation d'observateurs. Tout d'abord, nous avons appliqué deux types d'observateurs dans le cas d'une croissance identique pour toutes les tailles de cristaux. Ensuite, un observateur de type Kalman a été testé dans le cas d'une croissance dépendante de la taille des cristaux. La validation de l'identification et de l'estimation de la DTC a été effectuée par simulation. Ces résultats ont été très intéressants compte tenu du manque de mesures et du grand nombre d'états à estimerThe aim of this work is the estimation of crystal size distribution (CSD) of batch and polymorphic crystallization processes. The CSD evolution is described by partial differential equation (PDE) which requires the use of discretization methods. On line identification was realized in order to perform a real time correction of model parameters. An interesting alternative to CSD's sensors is the use of observers. First, we applied tow observers in the case of growth size independent. After that, a Kalman-like observer was tested in the case of growth size dependent. The validation of identification and estimation of the CSD was done by simulation. The results were very interesting with regard to the luck of measurements and the huge number of variables to estimateLYON1-BU.Sciences (692662101) / SudocSudocFranceF

Predictive control based on nonlinear observer for muscular force and fatigue model

International audienceThe Functional Electrical Stimulation (FES) is used in the case of neurological disorders (paralyzed muscles) or the muscle reinforcement (sportsmen). A recent model was proposed coupling a force model and a fatigue model. Based on the specific structure of the model, we present a predictive control scheme using online estimation of the fatigue variables with a nonlinear observer. It is numerically tested in a preliminary study

Antibacterial susceptibility profiles of subclinical mastitis pathogens isolated in Batna and Setif Governorates (East of Algeria)

Sub-clinical mastitis is a main pathology of dairy husbandry because it is not clinically recognized by the owners and the veterinarians. For this reason, its economic loss is usually underestimated in milk production. This study has been undertaken in order to evaluate the epidemiologic situation of sub-clinicalmastitis in Batna and Setif governorates (East of Algeria). For this purpose, a detailed bacteriological study of all bacterial strains isolated from sub-clinical mastitis followed by a study of their antibacterial susceptibility profiles has been undertaken. 89 bacterial strains distributed as follows were studied: 27 strains of staphylococci among which 23 were coagulase-negative staphylococci (CNS) that are generally incriminated in sub-clinical mastitis. 39 strains of streptococci among which 10 were Lactococcus lactis ssp lactis strains. 23 strains of enterobacteria represented mainly by Escherichia coli (E.coli). All these bacterial strains were isolated from cow milk of 3 different farms. The antibacterial susceptibility profiles have revealed a susceptibility of the isolated strains to a large number of antibiotics mainly to the Neomycin, the Cephalexin and the Spiramycin. [Vet. World 2011; 4(12.000): 537-541

Pontryagin-Type Conditions for Optimal Muscular Force Response to Functional Electric Stimulations

International audienceIn biomechanics recent mathematical models allow to predict the muscular force response to functional electrical stimulations (in short, FES).The main concern of the present paper is to deal with the computation of optimized electrical pulses trains (for example in view of maximizing the final force response). Using the fact that FES are modeled as Dirac pulses, our problem is rewritten as an optimal sampled-data control problem where the control parameters are the pulses amplitudes and the pulses times. We establish the corresponding Pontryagin first-order necessary optimality conditionsand we show how they can be used in view of numerical simulations