Dissertations / Theses on the topic 'Muscles – Modèles mathématiques'
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Funk, Catherine Irène. "Modélisation mathématique du système de phosphates à haute énergie au cours des échanges énergétiques de la cellule musculaire." Vandoeuvre-les-Nancy, INPL, 1990. http://www.theses.fr/1990INPL067N.
El, Makssoud Hassan. "Modélisation et identification des muscles squelettiques sous stimulation électrique fonctionnelle." Montpellier 2, 2005. http://www.theses.fr/2005MON20205.
El, Falou Wassim. "Une approche de la segmentation dans des signaux de longue durée fortement bruités : application en ergonomie." Troyes, 2002. http://www.theses.fr/2002TROY0008.
This work relates to develop a signal processing methodology dedicated to the characterization of very noisy long duration electromyographic signals (SEMG). The first step correspond to signal segmentation based on a cumulative sum algorithm, followed by rejection and classification procedures to lead to the extraction of relevant parameters for muscular fatigue detection. The method of segmentation was developed in order to detect the various activities included in the SEMG signal. An automatic approach of thresholds adjustment was carried out. The definition of two thresholds (high and low) led to a significant increase in the algorithm performance. The application domain of this work was the evaluation of SEMG as revealing the state of muscular fatigue, which would be induced by discomfort in long term driving tasks
Helal, Jean-Noël. "Discrimination de signaux électromyographiques non stationnaires : application à la contraction dynamique." Compiègne, 1990. http://www.theses.fr/1990COMPD229.
Ebadzadeh, Mohamad Mehdi. "Modélisation des voies réflexes et cérébelleuses, permettant le calcul des fonctions inverses : application à la commande d'un actionneur à deux muscles pneumatiques." Paris, ENST, 2004. http://www.theses.fr/2004ENST0046.
Bouchard, Stéphane. "Relation dynamique entre les signaux électromyographiques et le couple produit au coude lors de contractions à angles constants." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ60876.pdf.
El, Hajj Dib Imad. "Analyse et modélisation de l'EMG et de la fatigue musculaire lors de mouvements dynamiques cycliques." Compiègne, 2006. http://www.theses.fr/2006COMP1666.
The surface EMG is a non-invasive method which allows the diagnosis of the muscular function. Our study relates to fatigue in dynamic contraction. We achieved two parallel tasks: realization of experiments to collect real EMG, and model development to simulate synthetic EMG. The signal processing tools classically used to quantify fatigue are the Fourier transform, adapted to the isometric signals, and time-frequency, adapted to the dynamic signals. We were then interested in the cyclostationnarity. The results show that spectral coherence, cyclostationnarity tool, increases with muscular fatigue whereas the average traditional or instantaneous frequency, is mainly influenced by the action potential conduction velocity. Spectral coherence thus makes it possible to quantify fatigue under conditions where the traditional tools do not provide significant information
Cao, Hua. "Modélisation et évaluation expérimentale de la relation entre le signal EMG de surface et la force musculaire." Compiègne, 2010. http://www.theses.fr/2010COMP1856.
The estimation of the force generated by a muscle is important in biomechanical studies and clinical applications. As this force cannot be measured directly, the surface electromyography signal (SEMG), reflecting the level of muscle activation, is used to quantify the force developed. However, all the factors controlling an isometric contraction do not influence the force and the SEMG simultaneously. The aim of this study is to develop a simulation model of SEMG and force in order to study the EMG-force relationship. For this purpose, we first developed a new method to simulate the muscle force from an existing EMG model. We tested the complete model with two recruitment strategies and studied the influence of target force duration. Then we used a Monte Carlo method to study the sensitivity of the model to various input physiological parameters. Two existing criteria (EMG-force and force-force variability relationships) and a new criterion (error between the target force and the generated force) were used to optimize the parameters in constant target force contractions. This new criterion was then used in variable target force contractions (sinusoidal or triangular target) in order to obtain the optimum parameter ranges. Finally, to evaluate our model, we performed experiments and simulations for the biceps. The results have shown that our EMG-force model can qualitatively simulate the behaviour of the biceps for isotonic and anisotonic contractions
Laville, Aurélien. "Modélisation géométrique et mécanique du complexe musculo-squelettique du rachis cervical sous facteur de charge." Phd thesis, Paris, ENSAM, 2010. http://pastel.archives-ouvertes.fr/pastel-00553250.
Anderson, Judith. "Elasticité musculaire longitudinale et transversale : Influence de l'absence de desmine." Compiègne, 2000. http://www.theses.fr/2000COMP1315.
Douania, Inès. "Multi-scales, multi-physics personalized HD-sEMG model for the evaluation of skeletal muscle aging." Electronic Thesis or Diss., Compiègne, 2022. http://www.theses.fr/2022COMP2679.
The muscle aging, as a disease entity, is known as Sarcopenia. It is defined as a reduction of muscle strength/force accompanied by a loss of muscle mass and a decline in physical functions. The current methodologies used in clinical practice to assess this aging disease, are rather limited to capture the features of this decline at the macroscopic scale. Factors such as the loss of Motor Units (motor unit (MU) is made up of a motoneuron and all the skeletal muscle fibers innervated by the neuron's axon terminals), the atrophy of fibers and the disorder of the neural recruitment pattern are shown to have a clear influence on muscular function. However, diagnosing sarcopenia by only measuring the muscle strength and/or muscle mass is not enough accurate and cannot alert an early loss of muscular function. The inner scales (MU and fiber scale age-related changes) reflecting that loss of muscle mass and strength during aging are more interesting to exploit. Thus, recent studies, based on the surface electromyography (sEMG) technique, have demonstrated the great potential of this technique to be used as a biomarker to detect early signs of sarcopenic muscles. In fact, the sEMG signal is the electrical response of the muscle activation managed by the Central Nervous System (CNS). It is measured with a noninvasive manner at the skin surface using surface electrodes and can be correlated efficiently to the mechanical response of muscle activation. Moreover, mathematical models of sEMG signal can form a useful alliance with sEMG experimental measures and processing to identify and/or quantify bio-indicators (i.e., anatomical, and neural muscle parameters) of a healthy, early, accelerated or sarcopenic muscle aging. In this thesis work, we have used a fast and optimized electrical model describing the electrical activity of the muscle at the skin surface using High Density sEMG technique (HD-sEMG), developed in our laboratory team. The reduced computational time of this model is the major key feature to perform the identification of aging indicators using inverse methods and HD-sEMG technique. However, this identification needs pre-aided-methods such as the sensitivity and the identifiability analysis. Moreover, when dealing with this model, we have observed important limitations such as lack of physiological realism (e.g., MUS territories and the number of fibers per muscle), personalization (e.g., same recruitment pattern for young and elder subject), and simplicity (e.g., adjustment of 50 model parameters according to age and gender). These limitations restrain the use of this model in muscle aging diagnosis. Therefore, we aimed in this thesis to address the limitations of this model and deliver more realistic and user-friendly model to evaluate muscle aging. Therefore, in this work, we first propose an Improved Morris Sensitivity Analysis (IMSA) applied on the developed model. This analysis was performed on young and elder simulated subjects (at low and high force level). Using this IMSA, we success to spotlight with accuracy the influential neuromuscular parameters/factors for each age category, at each force level, and for each statistic feature computed over the HD-sEMG signals. Furthermore, using IMSA, we have outlined the model inaccuracies and limitations mentioned above. To address these limitations, we have modified the model schema implementation to be easier to manipulate (user-friendly model), with less error and inconsistency risks. Only the age and the gender of subject became needed as model entries to initiate a simulation of HD-sEMG signals. All other parameters necessary in simulations are then estimated through "statistical" models. The statistical models employ regression analysis to estimate the relation Parameter versus Age. A bibliographic research reporting these morphological and structural changes according to age, gender, and Biceps Brachii muscle was done
Gross, David. "Nage sous marine générée par boucle de rétroaction de courbure avec modélisation de muscles locomoteurs." Thesis, Université Côte d'Azur (ComUE), 2019. http://www.theses.fr/2019AZUR4053.
Undulatory wave-based self-propulsion like used by fish may be a suitable alternative to traditional propeller-based propulsion for underwater vehicles. The use of undulatory propulsion implies a certain degree of structural flexibility will be present, hence consideration of both fluid and structure is critical to assessing the behavior of this form of propulsion. In this thesis, a novel segregated fluid-structure interaction (FSI) coupling scheme is developed between a finite element structure solver and a 2D unsteady panel method fluid solver with discrete vortex particle wake approach. The different components of the FSI solver are validated first individually and then as a whole using the case of a flexible two-dimensional plate in pure heave. The scaling law relating input swimming variables and the resulting swimming speed is then reproduced and the importance of drag to these relations is elucidated.A self-propelled swimmer whose beam-like structure and rigid body motions are resolved is then examined under the influence of an imposed bending moment distribution. A curvature-based, delayed proprioceptive feedback is then applied to deform the self-propelled swimmer. Feedback based swimming was found to be distinct from active, imposed bending moment swimming. A simplified one degree of freedom model was found to qualitatively describe the feedback swimmer behavior. A swimmer using muscle-like elements is then assessed to determine the relative importance of different muscle properties with the aim of identifying if the non-linear behavior of muscles is beneficial to self-propulsion. Finally, a three-dimensional, thin plate in pure heave is examined with the aim of determining to what extent an 3D panel method can be used in lieu of computationally expensive viscous flow approaches self-propulsion analysis in 3D
Dakpé, Stéphanie. "Etude biomécanique de la mimique faciale." Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2203/document.
The aim of this research is to study facials mimics movements and to correlate externat soft tissue (i.e., cutaneous) movement during facial mimics with internal (i.e., facial mimic muscle) movement. The entire facial mimicry couldn't be studied, that's why relevant movements had been selected. Those movements were characterised by a clinically qualitative analysis in 23 young healthy volunteers. The analysis was performed with video recordings including scaling derived from the FACS (Facial Action Coding System). After the validation of external characterisation by this method, internal characterisation of the mimic facial muscle was carried out in 10 volunteers. A modelization of selected facial mimic muscle as Zygomaticus Major was achieved. With this work, morphological parameters could be extracted, 3D morphometric data were analysed to provide a better understanding of cinematic behaviour of muscle in different positions.This research is included in the Simovi Project, which aims to determine to what extent a facial mimic can be evaluated objectively, to select the qualitative and quantitative indicators for evaluation of mimic facial disorders, and to transfer our technological developments in clinical field. This research is a first step and provides data for simulation or developments of measurement tools in evaluation and follow-up of mimic facial disorders
Ayachi, Fouaz Sofiane. "Étude du recrutement des unités motrices par analyse du signal EMG de surface." Compiègne, 2011. http://www.theses.fr/2011COMP1998.
The central nervous system control the movement through the activation of the motors units (MUs), the smallest muscle functional structure. The MU produce electrical activity that can be detected by the technique of surface electromyography (sEMG). The stochastic nature of EMGs signal is mainly due to the superposition of trains of MU action potentials ( MUAPT) (spatial recruitment), the MUAPT are characterized by their discharge frequency (temporal recruitment) and the shape of the action potential (PA), which depends on some factors methodological and intrinsic to the muscle. The aim of this thesis is to study the possibilities and limitations of using the shape analysis of the EMGs signal’s probability density function (DP) as an indicator on MU recruitment strategies and motor control. This analysis seems relevant since the EMGs signal is the sum of random processes, the MUAPT. The contribution of this thesis is divided into two parts : the proposal of a complete model generation inspired by recent work from the literature. This model takes into consideration, for the EMGs signal generation, many physiological, anatomical and nervous parameters, as well as the force generation. Such consideration allows for greater realism in the simulation. The second part concerns several studies, simulation and experimental analysis of EMGs monopolar signals detected on the biceps brachii during isometric contractions isotonic (constant force) / anisotonique (graduated force). The aim is to extract information on the pattern of MU recruitment from these signals. In this context, we tested two approaches based on the shape analysis of the EMGs signal’s DP which are the Higher Order Statistics (HOS), and a recent algorithm, the Core Shape Modeling (CSM). The results indicate a high sensitivity of the proposed descriptors for separating classes of signals (force, sync level of the discharge), the filtering effect of adipose tissue and non propagating component. The efficiency of the classification depends the other hand of the anatomy and the number of MU which composed the muscle. For neuronal factors, both recruitment strategies tested give similar trends with one of them is physiologically more realistic. In addition, analysis of shape (SOS), in some cases, gives us information about muscle anatomy of the concerned muscle, in terms of MU position relative to the electrode. Concerning performance of classification, the algorithm CSM gives a result relatively better than SOS approach, either in simulation or experimentation. To summarize, this thesis is listed as an exploratory process of the shape analysis potential of the EMGs signal’s DP in order to extract the information on the muscular activation’s modalities. A lot of efforts are still required in accordance with the perspectives offered
Carriou, Vincent. "Multiscale, multiphysic modeling of the skeletal muscle during isometric contraction." Thesis, Compiègne, 2017. http://www.theses.fr/2017COMP2376/document.
The neuromuscular and musculoskeletal systems are complex System of Systems (SoS) that perfectly interact to provide motion. From this interaction, muscular force is generated from the muscle activation commanded by the Central Nervous System (CNS) that pilots joint motion. In parallel an electrical activity of the muscle is generated driven by the same command of the CNS. This electrical activity can be measured at the skin surface using electrodes, namely the surface electromyogram (sEMG). The knowledge of how these muscle out comes are generated is highly important in biomechanical and clinical applications. Evaluating and quantifying the interactions arising during the muscle activation are hard and complex to investigate in experimental conditions. Therefore, it is necessary to develop a way to describe and estimate it. In the bioengineering literature, several models of the sEMG and the force generation are provided. They are principally used to describe subparts of themuscular outcomes. These models suffer from several important limitations such lacks of physiological realism, personalization, and representability when a complete muscle is considered. In this work, we propose to construct bioreliable, personalized and fast models describing electrical and mechanical activities of the muscle during contraction. For this purpose, we first propose a model describing the electrical activity at the skin surface of the muscle where this electrical activity is determined from a voluntary command of the Peripheral Nervous System (PNS), activating the muscle fibers that generate a depolarization of their membrane that is filtered by the limbvolume. Once this electrical activity is computed, the recording system, i.e. the High Density sEMG (HD-sEMG) grid is define over the skin where the sEMG signal is determined as a numerical integration of the electrical activity under the electrode area. In this model, the limb is considered as a multilayered cylinder where muscle, adipose and skin tissues are described. Therefore, we propose a mechanical model described at the Motor Unit (MU) scale. The mechanical outcomes (muscle force, stiffness and deformation) are determined from the same voluntary command of the PNS, and is based on the Huxley sliding filaments model upscale at the MU scale using the distribution-moment theory proposed by Zahalak. This model is validated with force profile recorded from a subject implanted with an electrical stimulation device. Finally, we proposed three applications of the proposed models to illustrate their reliability and usefulness. A global sensitivity analysis of the statistics computed over the sEMG signals according to variation of the HD-sEMG electrode grid is performed. Then, we proposed in collaboration a new HDsEMG/force relationship, using personalized simulated data of the Biceps Brachii from the electrical model and a Twitch based model to estimate a specific force profile corresponding to a specific sEMG sensor network and muscle configuration. To conclude, a deformableelectro-mechanicalmodelcouplingthetwoproposedmodelsisproposed. This deformable model updates the limb cylinder anatomy considering isovolumic assumption and respecting incompressible property of the muscle
Fan, Ang-Xiao. "Geometric and numerical modeling of facial mimics derived from Magnetic Resonance Imaging (MRI) using Finite Element Method (FEM)." Thesis, Compiègne, 2016. http://www.theses.fr/2016COMP2307.
Human face plays an important role interpersonal communication. Facial dysfunction or disfigurement due to trauma or pathologies may impede normal social activities. Surgical treatment is often necessary. Nowadays, treatment outcome and rehabilitation condition are estimated only by qualitative methods, such as visual observation and palpation. In expectation of providing quantitative criteria, this thesis proposes to model facial mimics using FEM (Finite Element Method) on the basis of MRI (Magnetic Resonance Imaging) data. A subject-specific face model was reconstructed based on segmentation of MRI data; it contains bony parts, mimic muscles (e.g. zygomaticus major muscle), subcutaneous soft tissues and skin. Identification of biological soft tissues was conducted through bi-axial tension tests and numerical modeling. Then the geometric model was meshed to conduct FE calculations simulating three facial mimic movements (smile, pronunciation of sound “Pou” and “O”). Muscle was modeled as quasi-incompressible, transversely-isotropic, hyperelastic material, with activation ability. Relevant information (e.g. contraction amplitude of muscle) used in simulation was extracted from measurement of MRI data. It is to be noted that the same experimental MRI data as used in modeling was taken as validation reference for simulation results. This study can be applied clinically in evaluation of facial treatment andpostoperative recovery
Nowakowski, Katharine. "The prediction and management of muscle ageing : 3D musculoskeletal simulations and multi-scale biomechanical modeling for the analysis of human falls and fall prevention strategies through the application of artificial intelligence approaches." Electronic Thesis or Diss., Compiègne, 2023. http://www.theses.fr/2023COMP2763.
The age-related decline in muscle function is linked to both sarcopenia and an increased risk for falls. In this doctoral project, an analysis of the morphological, functional, mechanical and biophysical parameters known to be affected by ageing is presented. The data has been analysed with statistical and machine learning techniques. These results influenced the development of a deep reinforcement learning simulation for both young adult and elderly falls, based on the parameters sensitive to ageing such as maximum isometric force, contraction velocity, deactivation time, passive muscle strain, hip extension range and a mass shift from the legs to the trunk. Testing of the sensitivity of the results then led to the development of a coupled simulation to study falls recovery, where the effects of sensory nerves and proprioception was considered. The strategy for coupling allows for recovery for any fall position to be analysed to further test the limits of recovery produced by the given model. The results from each aspect of the project suggest that muscle ageing can be further elucidated through the development of a multi-scale model that could consider fatigue and the effect of biophysical changes on movement outcomes. A multi-scale model, where agent-based modelling is coupled to a reinforcement learning environment is proposed. The model accounts for the conversion of type II muscle fibres to type I fibres, as well as considers the dynamics of calcium, inorganic phosphate, and ATP, with prospective for further adaptations. This work demonstrates the interest in further exploration of complex human system modelling by leveraging artificial intelligence techniques
Serhan, Hayssam. "Approches biomimétiques pour le contrôle de la marche des robots bipèdes : stratégie intuitive et intégration d'un modèle de muscle." Versailles-St Quentin en Yvelines, 2009. http://www.theses.fr/2009VERS0045.
The approach proposed in this thesis is to update the parameters of a PID controller using a specialized learning algorithm in order to reproduce the fluids and tonics that can be observed in human walking gaits. This approach is based on neural techniques and techniques of dynamic walking modeling of the human being. Experimental data are extracted from the work of LISV as part of its activities on disability with the functional rehabilitation department of the Raymond Poincaré hospital in Garches. In a first stage a non-linear model of a muscle based on a neural network has been identified and used as a reference model for learning another neural network which regulates online the parameters of a PID controller in a way for the physical system [PID Controller + Motor] to behave like the muscle model. In order to validate our study, in a first time, a dynamic simulation of the robot ROBIAN of LISV has been developed under OPENHRP. In a second step, an original approach to the 3D dynamic walking has been implemented in this simulator. Finally the physical model of muscle already developed is incorporated into the algorithm for generating the walking cycles of ROBIAN. The set is simulated under OPENHRP. The results show that the online learning of the PID parameters of the knee from the neural model of muscle, did improve the fluidity of movement, increased robustness against perurbations (lateral and frontal push) and walk-stop-walk transitions. Compararaison with human walking is conducted along with an assessment of power consumption compatibility with ROBIAN motors
Mabit, Christian. "Etude biomécanique des poutres composites : application au rachis lombaire et à la voûte plantaire." Montpellier 1, 1995. http://www.theses.fr/1995MON1T027.
Philippe, Antony. "Effets de l'entraînement en résistance, de la performance à l'unité contractile." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONT4002/document.
This thesis work aims to improve our understanding of the effects of resistance training on performance and skeletal muscle. The dynamic of these effects of training has been apprehended systematically trough tools from systems theory, with 26 rodents resistance trained on a climbing protocol with additional weights. The classical model (Banister et al, 1975) was suitable to analyze the training response (R2 = 0.53, P <0.001). The origin of the very marked performance gains (+ 136% compared to the control group) was investigated among the potential muscle adaptive mechanisms. At the end of the training program, an increase of 123 ± 61% in myosin ATPase activity independent of the phenotype was observed compared to control animals. This increase in myosin ATPase activity seems to occur precisely during the main myosin head isomerization step (i.e. powerstroke) that includes the liberation of the hydrolysis products, and to a lesser extent, during ATP hydrolysis step. A new form of muscular plasticity seems identified. Based on muscle adaptive mechanisms, a new mathematical formulation, more physiological, of the model of the training effects has been proposed and resulted in a better fit (R2 = 0.71, P <0.001). The impulse function of the traditional model has been replaced by an exponential growth function that seems more suitable to analyze both the training response and the adaptations that occur within the muscle tissue as in the contractile units themselves
Allouch, Samar. "Modélisation inverse du système neuromusculosquelettique : application au doigt majeur." Thesis, Compiègne, 2014. http://www.theses.fr/2014COMP2157.
With the need to develop an artificial organ replacing the human finger in the case of a deficiency and the need to understand how this physiological system works, an inverse physical model of the finger system for estimating neuronal activations from the movement, is necessary. Despite the large number of studies in the human hand modeling, almost there is no inverse physical model of the middle finger system that focuses on search neuronal activations. Al most all existing models have focused on the research of the muscle forces and muscle activations. The purpose of the manuscript is to present a neuromusculoskeletal model of the human middle finger system for estimating neuronal activations, muscle activations and muscle forces of all the acting muscles after movement analysis. The aim of such models is to represent the essential characteristics of the movement with the best possible realism. Our job is to study, model and simulate the movement of the human finger. The innovation of the proposed model is the coupling between the biomechanical and neurophysiological aspects to simulate the complete inverse movement chain from dynamic finger data to neuronal intents that control muscle activations. Another innovation is the design of a specific experimental protocol that treats both the multichannel sEMG and kinematic data from a data capture procedure of the movement
Benoussaad, Mourad. "Protocole d'identification sous FES et synthèse des séquences de stimulation chez le blessé médullaire." Montpellier 2, 2009. http://www.theses.fr/2009MON20236.
Under spinal cord injury, the natural control of limbs becomes impossible, which leads to partial or totale paralysis. Functional Electrical Stimulation (FES) may then be used to substitute the central nervous system by contracting the skeletal muscles for mouvement rehabilitation of paralysed muscle-limb. In addition, FES presents many therapeutic benefits for SCI patients. However, its application poses some problems in practice. Indeed, the applied stimulation patterns are always empirically tuned, increasing the muscular fatigue and limiting the use to short periods of time. Thus, an accurate numerical model of the muscle-limb dynamics is needed which involve an experimental parameters identification procedure. The main contributions of this thesis are 1) A parameters identification set up of a musculoskeletal physiological model in spinal cord injured subjects and 2) Synthesis of functional electrical stimulation patterns based on the identified model
Kromer, Valérie. "Analyse des forces musculaires au cours de la marche : approche en corps rigide et simulation en mécanismes plans flexibles par éléments finis." Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL040N.
Stelletta, Julien. "Modélisation volumique déformable du système musculosquelettique du membre inférieur." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10107/document.
Musculo-skeletal modeling can update our knowledge concerning the biomechanical behavior of the osteoarticular and musculotendinous structures. This research work is focus on the development of methodology and tools for the generation of a personalized model of the lower limb musculoskeletal system, taking account of the deformable and contractile behavior of the muscles. This workflow automatically builds the model dataset (from medical imagery), performs the simulations (coupled with a multibody dynamic model), and offers specific analysis tools (as local stiffness mapping in the active muscle) required for various orthopedic studies
Benoussaad, Mourad. "Protocole d'identification sous FES et synthèse des séquences de stimulation chez le blessé médullaire." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2009. http://tel.archives-ouvertes.fr/tel-00452009.
Al, Harrach Mariam. "Modeling of the sEMG / Force relationship by data analysis of high resolution sensor network." Thesis, Compiègne, 2016. http://www.theses.fr/2016COMP2298/document.
The neuromuscular and musculoskeletal systems are complex System of Systems (SoS) that perfectly interact to provide motion. This interaction is illustrated by the muscular force, generated by muscle activation driven by the Central Nervous System (CNS) which pilots joint motion. The knowledge of the force level is highly important in biomechanical and clinical applications. However, the recording of the force produced by a unique muscle is impossible using noninvasive procedures. Therefore, it is necessary to develop a way to estimate it. The muscle activation also generates another electric phenomenon, measured at the skin using electrodes, namely the surface electromyogram (sEMG). ln the biomechanics literature, several models of the sEMG/force relationship are provided. They are principally used to command musculoskeletal models. However, these models suffer from several important limitations such lacks of physiological realism, personalization, and representability when using single sEMG channel input. ln this work, we propose to construct a model of the sEMG/force relationship for the Biceps Brachii (BB) based on the data analysis of a High Density sEMG (HD-sEMG) sensor network. For this purpose, we first have to prepare the data for the processing stage by denoising the sEMG signals and removing the parasite signals. Therefore, we propose a HD-sEMG denoising procedure based on Canonical Correlation Analysis (CCA) that removes two types of noise that degrade the sEMG signals and a source separation method that combines CCA and image segmentation in order to separate the electrical activities of the BB and the Brachialis (BR). Second, we have to extract the information from an 8 X 8 HD-sEMG electrode grid in order to form the input of the sEMG/force model Thusly, we investigated different parameters that describe muscle activation and can affect the relationship shape then we applied data fusion through an image segmentation algorithm. Finally, we proposed a new HDsEMG/force relationship, using simulated data from a realistic HD-sEMG generation model of the BB and a Twitch based model to estimate a specific force profile corresponding to a specific sEMG sensor network and muscle configuration. Then, we tested this new relationship in force estimation using both machine learning and analytical approaches. This study is motivated by the impossibility of obtaining the intrinsic force from one muscle in experimentation
Georges, Gabriel. "Développement d’un schéma aux volumes finis centré lagrangien pour la résolution 3D des équations de l’hydrodynamique et de l’hyperélasticité." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0130/document.
High Energy Density Physics (HEDP) flows are multi-material flows characterizedby strong shock waves and large changes in the domain shape due to rarefactionwaves. Numerical schemes based on the Lagrangian formalism are good candidatesto model this kind of flows since the computational grid follows the fluid motion.This provides accurate results around the shocks as well as a natural tracking ofmulti-material interfaces and free-surfaces. In particular, cell-centered Finite VolumeLagrangian schemes such as GLACE (Godunov-type LAgrangian scheme Conservativefor total Energy) and EUCCLHYD (Explicit Unstructured Cell-CenteredLagrangian HYDrodynamics) provide good results on both the modeling of gas dynamicsand elastic-plastic equations. The work produced during this PhD thesisis in continuity with the work of Maire and Nkonga [JCP, 2009] for the hydrodynamicpart and the work of Kluth and Després [JCP, 2010] for the hyperelasticitypart. More precisely, the aim of this thesis is to develop robust and accurate methodsfor the 3D extension of the EUCCLHYD scheme with a second-order extensionbased on MUSCL (Monotonic Upstream-centered Scheme for Conservation Laws)and GRP (Generalized Riemann Problem) procedures. A particular care is taken onthe preservation of symmetries and the monotonicity of the solutions. The schemerobustness and accuracy are assessed on numerous Lagrangian test cases for whichthe 3D extensions are very challenging
Treffel, Loïc. "Dysfonctions vertébrales et posturales après simulations de la microgravité." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAJ111/document.
This work focuses on the study of back pain experienced by astronauts, who present with a greater incidence of herniated discs compared to a control population. Our research aims at understanding the physiopathology of this phenomenon and to study the clinical consequences of vertebral deconditioning which also contributes to postural disorders. This line of research has been recommended by the various international space agencies. For this reason, we had the opportunity to analyze data in two models simulating the effects of microgravity: dry immersion (n = 11) and head-down bed rest (n = 9), and a similar state, confinement (n = 4). Only the main results of dry immersion, a new method of studying our paradigm, are reported in this summary. Using magnetic resonance imaging and spectroscopy of the vertebral column, it was possible to analyze the intervertebral disc in 3 dimensions and to objectify the increase in water content (+ 17%) and the increase in intervertebral disc volume (+ 9.5%). Variations in paravertebral and lower limb muscle tone were measured with the very recent, and non-invasive, MyotonPRO technology. A decrease in muscle tone (-7.3%) was found to be associated with muscular atrophy (-10.6%) as well as a loss of strength in the lower limbs. These results, attesting to muscle deconditioning, are consistent with postural impairment immediately after dry immersion. We also studied variations in dental occlusion, which is involved with the maintenance of posture and could affect balance. In summary, two elements are involved in the explanation of vertebral dysfunction: the increase in spine height, related to increased intervertebral discs volume and paravertebral muscles atrophy, which plays a major role in posture. However, we also showed a role of dental occlusion in vertebral and postural deconditioning. In conclusion: muscle tone, good vertebral mobility, and dental occlusion are elements to be preserve during and after an exposure to weightlessness to avoid the deleterious effects of deconditioning
Comtois, Philippe. "Stabilité de la réentrée anatomique dans le muscle cardiaque et annihilation par un protocole à deux stimulations : études de modélisation et aspects expérimentaux." Thèse, 2003. http://hdl.handle.net/1866/15113.