Dissertations / Theses: 'LPV approach'

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Attallah, Aly [Verfasser]. "Distributed Control for Complex Mission Scenarios With Non-Holonomic Agents - An LPV Approach / Aly Attallah." München : Verlag Dr. Hut, 2021. http://d-nb.info/1238423078/34.

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Buľák, Marián. "Trendy modernizace technologií pro řízení letů v okolí civilních letišť." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401509.

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This master’s thesis deals with technologies intended for flight control during approach and landing. The main focus is on perspective approach systems, including differential technology systems. The thesis is to serve as a study aid for pilots and students of Air Traffic study programme. The main aim of this thesis is to create a qualified whole of perspective and used approach systems. Individual systems include basic characteristics and assessment of their future use. The thesis also includes an analysis of the possibility of implementing the DGNSS system at the airport with multiple runways. Prague-Ruzyně airport was chosen for this purpose. The implementation of this system is compared to other precision approach systems.

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Attallah, Aly [Verfasser]. "Distributed control for complex mission scenarios with non-holonomic agents – an LPV approach / Aly Saeed Aly Aly Attallah." Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2021. http://nbn-resolving.de/urn:nbn:de:gbv:830-882.0135993.

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Petersson, Daniel. "A Nonlinear Optimization Approach to H2-Optimal Modeling and Control." Doctoral thesis, Linköpings universitet, Reglerteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-93324.

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Mathematical models of physical systems are pervasive in engineering. These models can be used to analyze properties of the system, to simulate the system, or synthesize controllers. However, many of these models are too complex or too large for standard analysis and synthesis methods to be applicable. Hence, there is a need to reduce the complexity of models. In this thesis, techniques for reducing complexity of large linear time-invariant (lti) state-space models and linear parameter-varying (lpv) models are presented. Additionally, a method for synthesizing controllers is also presented. The methods in this thesis all revolve around a system theoretical measure called the H2-norm, and the minimization of this norm using nonlinear optimization. Since the optimization problems rapidly grow large, significant effort is spent on understanding and exploiting the inherent structures available in the problems to reduce the computational complexity when performing the optimization. The first part of the thesis addresses the classical model-reduction problem of lti state-space models. Various H2 problems are formulated and solved using the proposed structure-exploiting nonlinear optimization technique. The standard problem formulation is extended to incorporate also frequency-weighted problems and norms defined on finite frequency intervals, both for continuous and discrete-time models. Additionally, a regularization-based method to account for uncertainty in data is explored. Several examples reveal that the method is highly competitive with alternative approaches. Techniques for finding lpv models from data, and reducing the complexity of lpv models are presented. The basic ideas introduced in the first part of the thesis are extended to the lpv case, once again covering a range of different setups. lpv models are commonly used for analysis and synthesis of controllers, but the efficiency of these methods depends highly on a particular algebraic structure in the lpv models. A method to account for and derive models suitable for controller synthesis is proposed. Many of the methods are thoroughly tested on a realistic modeling problem arising in the design and flight clearance of an Airbus aircraft model. Finally, output-feedback H2 controller synthesis for lpv models is addressed by generalizing the ideas and methods used for modeling. One of the ideas here is to skip the lpv modeling phase before creating the controller, and instead synthesize the controller directly from the data, which classically would have been used to generate a model to be used in the controller synthesis problem. The method specializes to standard output-feedback H2 controller synthesis in the lti case, and favorable comparisons with alternative state-of-the-art implementations are presented.

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Yamamoto, Kazusa. "Control of electromechanical systems, application on electric power steering systems." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAT069/document.

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De nos jours, la plupart des véhicules sont équipés de Directions Assistées Electriques (DAE). Ce type de systèmes d'aide à la conduite permet de réduire les efforts que le conducteur doit fournir pour tourner les roues. Ainsi, grâce à un moteur électrique, la DAE applique un couple additionnel en accord avec le comportement du conducteur et la dynamique du véhicule. Il est donc nécessaire de développer une commande en couple basée en particulier sur le signal provenant d'un capteur mesurant le couple agissant au niveau de la barre de torsion (correspondant à une image du couple conducteur). Ce composant est donc essentiel au fonctionnement de la DAE. Or, une défaillance de ce capteur entraine le plus souvent une coupure de l'assistance, pouvant mener à un risque d'accidents. Au regard de la sécurité fonctionnelle, un développement d'un mode de sécurité est recommandé, par de plus en plus de constructeurs automobiles. D'autre part, le marché des équipementiers automobiles reste un secteur très concurrentiel où une baisse des coûts de production est un challenge constamment recherché afin de gagner de nouvelles parts de marchés. Cet aspect de réduction du nombre de capteurs et d'analyse de la dynamique du véhicule s'inscrit donc dans le prolongement de la stratégie de sécurité. Cette thèse, menée au sein de JTEKT Europe, aborde ces divers enjeux. Après une présentation des différents systèmes de directions assistés électriques, des modèles sont présentés pour être utilisés lors de la conception de lois de commande et d'estimateurs. Ensuite deux méthodes d'estimation du couple conducteur sujet aux perturbations de la route et aux bruits de mesures sont proposées : la première est un observateur proportionnel intégral (PI) à synthèse mixte $H_infty/H_2$, et la seconde une approche par filtrage $H_infty$. Puis plusieurs stratégies de commande sont proposées suivant deux cas de figures distincts, soit en utilisant un observateur PI qui estime les états du système et le couple conducteur (LQR, commande LPV par retour d'état), soit en faisant abstraction d'estimateur de couple conducteur (commande $H_infty$ par retour de sortie dynamique). Ce dernier aspect présente l'avantage de nécessiter moins de mesures que le précédent. Ces approches ont été validées en simulation et mises en œuvre sur un véhicule prototype où des résultats prometteurs ont été obtenus
Nowadays, modern vehicles are equipped with more and more driving assistance systems, among them Electric Power Steering (EPS) helps the driver to turn the wheels. Indeed, EPS provides through an electric motor, an additional torque according to the driver's behaviour and the vehicle's dynamics to reduce the amount of effort required to the driver. Therefore, a torque control is developed based on the torque sensor signal which measures in practice the torsion bar torque (corresponding to an image of the driver torque). Consequently, this component is essential to the functioning of EPS systems.Indeed, a torque sensor failure usually leads to shut-off the assistance which may increase the risk of accident. Regarding functional safety, a back-up mode is recommended and required by more and more car manufacturers. On the other hand, a major challenge for automotive suppliers is to reduce cost production in order to meet growing markets demands and manage in the competitive sector. This issue considering a reduction of sensors' numbers and analysis of vehicle's dynamics is therefore an extension of applying the safety strategy. This thesis, carried out within JTEKT Europe, addresses these various issues.After introducing an overview of the different EPS systems, some models used for the design of controllers and estimators are presented. Then, two methods to estimate the driver torque subject to road disturbances and noise measurements are proposed: the first is a proportional integral observer (PI) with mixed synthesis $H_infty / H_2 $, whereas the second is an $ H_infty $ filtering approach. Then, several control strategies are proposed according to two different cases, either by using a PI observer which estimates the system states and the driver torque (LQR, LPV feedback control) or by not taking into account the driver torque estimation ($ H_infty $dynamic output feedback control). This latter approach has the advantage to require less measurements than the previous one. These approaches have been validated in simulation and implemented on a prototype vehicle where promising results have been obtained

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Bouchama, Fawzia. "Synthèse d’observateurs continus-discrets pour les systèmes non linéaires : Application au Train Autonome." Electronic Thesis or Diss., Valenciennes, Université Polytechnique Hauts-de-France, 2024. http://www.theses.fr/2024UPHF0005.

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Ce travail de thèse contribue au projet collaboratif "Train de Fret Autonome'' porté par la SNCF et a pour but d’automatiser la conduite du train de Fret afin de garantir une conduite autonome fiable et sécurisée dans toutes conditions environnementales. Dans ce contexte, nos contributions concernent le développement d’estimateurs permettant de reconstruire avec précision la position et la vitesse longitudinale du train dans des conditions variables d’adhérence roue-rail. La difficulté majeure provient du fait que les capteurs odométriques embarqués fournissent une mesure de la rotation des roues au niveau des essieux mais ne détectent pas directement le phénomène de glissement des roues, ce qui entraîne une grande imprécision au niveau de l’estimation de la vitesse longitudinale du train. Pour faire face à ce problème, il est nécessaire de faire un recalage précis en utilisant la position du train mesurée par des radio-balises installées sur le rail. Néanmoins, cette mesure est discrète avec une période d’échantillonnage variable. L’un des challenges est de considérer les mesures du train qui combinent à la fois des mesures considérées continues et des mesures apériodiquement échantillonnées. Ainsi, la principale contribution théorique de cette thèse est la conception d’un observateur continu-discret pour une classe de systèmes multi-entrées/multi-sorties avec des sorties continues entachées de bruits de mesures et des sorties apériodiquement échantillonnées. Cet observateur est conçu pour répondre au cahier de charge du projet ``Train de Fret Autonome'' afin d’estimer la vitesse du train dans des conditions variables d’adhérence. Les performances de cet observateur sont montrées en simulation et comparées avec d’autres approches d’estimation de la vitesse du train puis ensuite validées expérimentalement via une campagne d’essais réalisée au Centre d’Essai Ferroviaire de Tronville-en-Barrois
This thesis contributes to the collaborative project "Train de Fret Autonome'' led by the SNCF and aims to control autonomous freight trains in order to guarantee reliable and safe autonomous driving in all environmental conditions. In this context, our contributions concern the development of estimators for accurately reconstructing the train position and longitudinal speed under variable wheel-rail adhesion conditions. The major difficulty arises from the fact that on-board odometric sensors provide a measurement of wheel rotation at axle level, but do not directly detect the phenomenon of wheel slippage, resulting in inaccurate estimation of the longitudinal speed of the train. To overcome this problem, it is necessary to make a precise recalibration using the position of the train measured by radio beacons installed on the rail. Nevertheless, this measurement is discrete with a variable sampling period. One of the challenges is to consider train measurements that combine both continuous and aperiodically sampled measurements. Thus, the main theoretical contribution of this thesis is the design of a continuous-discrete observer for a class of multi-input/multi-output systems with continuous noisy outputs and aperiodically sampled outputs. This observer is designed to meet the specifications of the "Autonomous Freight Train" project, in order to estimate train speed under variable adhesion conditions. The performance of this observer is shown in simulation and compared with other approaches to train speed estimation, then validated experimentally via an experimental test program carried out at the Centre d'Essai Ferroviaire of Tronville-en-Barrois

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Hvězda, Michal. "Model systému automatického řízení přesného přiblížení a přistání civilního dopravního letadla za použití informací DGNSS." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-438882.

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LPV approaches are being published in the Czech Republic nowadays. Their usage is enabled by the EGNOS European satellite augmentation system. However, published decision heights do not allow equivalence with the ILS CAT I precision approach yet. This work presents the model of automated control of aircraft precision approach. Verification of its functionality shows that applicable airspace requirements can be fulfilled for lower values of decision heights than values already published. The model is developed using contemporary methods of model-based development in the tool supporting common processing of both continuous and discrete signals. Although model architecture follows the structure of commonly used ILS system in definition of coordinate system and in establishing control in two separate directions it allows curved approach. Usage of digital navigation data provided by satellite system opens further opportunities in its usage, expansion and improvements. Model functionality in control of flight course, position and height control is verified in the scenarios covering detailed thesis goals. The goals were defined based on definition of precision approach process and include navigation signal drop-out, impact of wind, various flight path angles and curved approach. Analysis of behavior of controlled aircraft dynamics was a stimulator for research of specific system modules up to the application level, i.e. specific simulations of successful precision approaches.

8

Do, Anh Lam. "Approche LPV pour la commande robuste de la dynamique des véhicules : amélioration conjointe du confort et de la sécurité." Thesis, Grenoble, 2011. http://www.theses.fr/2011GRENT114/document.

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Ce travail concerne le développement de méthodes de commandes avancées pour les suspensions automobiles afin d'améliorer la tenue de route des véhicules et le confort des passagers, tout en respectant les contraintes technologiques liées aux actionneurs de suspension (passivité, non-linéarités, limite structurelle). Dans la 1ère partie, nous proposons deux schémas de commande par approche LPV polytopique (Linéaire à Paramètre Variant) et Stabilisation Forte (Strong Stabilization) avec optimisation par algorithme génétique pour résoudre les conflits confort/tenue de route et confort/débattement de suspension. Dans la 2ème partie, pour résoudre le problème complet de commande de suspensions semi-actives, nous développons d'abord une stratégie générique pour les systèmes LPV généraux soumis à la saturation des actionneurs et à des contraintes d'état. Le problème est étudié sous la forme de résolution d'inégalités linéaires matricielles (LMI) qui permettent de synthétiser un contrôleur LPV et un gain anti wind-up garantissant la stabilité et la performance du système en boucle fermée. Ensuite, cette stratégie est appliquée au cas de la commande des suspensions semi-actives. Les méthodes proposées sont validées par une évaluation basée sur un critère industriel et des simulations effectuées sur un modèle non-linéaire de quart de véhicule
This work concerns the development of advanced control methods for automotive suspensions to improve road holding and passenger comfort, while satisfying the technological constraints related to the suspension actuators (passivity, nonlinearity, structural limit). In the first part, we propose two control schemes by polytopic LPV (Linear Parameter Varying) approach and by Strong Stabilization with genetic algorithm optimization to solve the comfort/handling and comfort/suspension travel conflits. In the second part, to solve the full semi-active suspension problem, we develop first a generic strategy for general LPV systems subject to actuator saturation and state constraints. The problem is studied in the form of resolution matrix of linear inequalities (LMI) that allows synthesizing an LPV controller and an anti-windup gain to ensure the stability and performance of the closed-loop system. Second, the theoretical result is applied to the case of semi-active suspension control. The proposed methods are validated by an evaluation based on an industrial standard and simulations on a nonlinear quarter vehicle model

9

Petersson, Daniel. "Nonlinear optimization approaches to H2-norm based LPV modelling and control." Licentiate thesis, Linköpings universitet, Reglerteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-59886.

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To be able to analyze certain classes of non-linear systems, it is necessary to try to represent them as linear parameter varying systems or even as linear fractional representations. For linear parameter varying systems and linear fractional representations of systems there exists many advanced analysis methods such as IQC-analysis and μ-analysis. This means that an important intermediate step in all this is to generate a linear parameter varying model that describes these non-linear system sufficiently well. The first contribution in this thesis is a novel method that tries, through nonlinear programming and a quasi-Newton framework, to generate a linear parameter varying model given linearized state space models. The idea behind the method is to preserve the input-output relations of the given linearized systems and, in an H2-measure, find the best one. To handle uncertainties in data an extension of the proposed method is presented. It is shown how the computationally hard robust optimization approach to the uncertain case can be approximated using a problem specific regularization. The second contribution in this thesis is a method for synthesizing output-feedback H2 controllers of arbitrary order. This method also uses non-linear programming and a quasi-Newton framework to achieve this. One great benefit with this method is that it also possible to impose structure in the controller. Both of the methods described above tries to solve non-linear and non-convex problems, which means that the problem of finding a good initial estimate is an important problem. For both methods an initialization procedure is proposed to try to find an initial estimate. The methods are evaluated on several examples and show promising results. A contributing factor is that significant effort has been spent on utilizing the structure of the optimization problems to make the methods efficient.

10

Bouali, Anis. "Approche descripteur pour l’analyse et la commande des systèmes LPV rationnels." Nantes, 2008. http://www.theses.fr/2008NANT2119.

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Les caractéristiques dynamiques des processus évoluent parfois largement en fonction des conditions de fonctionnement. Dans ce cas le comportement du système est souvent décrit par un modèle linéaire à paramètres variant (LPV). Cette modélisation recouvre des cas pratiques importants non couverts par les modèles linéaires invariants dans le temps (LTI), sans avoir une généralité telle qu’aucun outil générique ne permette leur analyse ou leur commande. Une sous classe des systèmes LPV se dégage de part sa complexité : celle des systèmes LPV rationnels. Nous démontrons qu’une telle classe de systèmes admet toujours une modélisation équivalente du type LPV descripteur, dite aussi LPV implicite, avec une dépendance paramétrique du type affine. Nous développons un ensemble d’outils d’analyse et de commande pour les systèmes LPV implicites affines. Ces outils sont présentés sous la forme de problèmes d’optimisation sous contraintes LMI (Inégalités Matricielles Linéaires) paramétriques. Leur résolution est grandement facilitée de part la nature affine du modèle implicite considéré. En se basant sur ces résultats et sur une nouvelle notion d’équivalence, nous proposons des outils pour l’analyse, la commande ainsi que la paramétrisation des régulateurs stabilisants des systèmes LPV rationnels. Enfin, quelques exemples numériques permettent d’illustrer ces nouveaux outils et d’en apprécier les intérêts et les limites
Linear parameter dependent models are useful to describe behavior of plants with dynamical characteristics evolving widely with operating conditions. Such models are more general then linear time invariant ones. Among the class of LPV systems those with a rational dependency on the varying parameter are of particular interest. It is shown in this work that such systems can always be recast into equivalent descriptor systems with an affine dependency on the parameters. Original methods for the analysis and the control of LPV descriptor systems have been proposed. In the case of affine descriptor systems, these methods rely on optimization problems having LMI characterizations. Such problems are known to be highly tractable. Based on these results and the properties of the strong equivalence, new conditions for the analysis and the control of rational LPV systems as well as a parameterization of all stabilizing controllers have been presented. Finally, some numerical examples are given in order to appreciate the interest and limitations of the proposed results

11

Do, Anh Lam. "Approche LPV pour la commande robuste de la dynamique des véhicules : amélioration conjointe du confort et de la sécurité." Electronic Thesis or Diss., Grenoble, 2011. http://www.theses.fr/2011GRENT114.

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Ce travail concerne le développement de méthodes de commandes avancées pour les suspensions automobiles afin d'améliorer la tenue de route des véhicules et le confort des passagers, tout en respectant les contraintes technologiques liées aux actionneurs de suspension (passivité, non-linéarités, limite structurelle). Dans la 1ère partie, nous proposons deux schémas de commande par approche LPV polytopique (Linéaire à Paramètre Variant) et Stabilisation Forte (Strong Stabilization) avec optimisation par algorithme génétique pour résoudre les conflits confort/tenue de route et confort/débattement de suspension. Dans la 2ème partie, pour résoudre le problème complet de commande de suspensions semi-actives, nous développons d'abord une stratégie générique pour les systèmes LPV généraux soumis à la saturation des actionneurs et à des contraintes d'état. Le problème est étudié sous la forme de résolution d'inégalités linéaires matricielles (LMI) qui permettent de synthétiser un contrôleur LPV et un gain anti wind-up garantissant la stabilité et la performance du système en boucle fermée. Ensuite, cette stratégie est appliquée au cas de la commande des suspensions semi-actives. Les méthodes proposées sont validées par une évaluation basée sur un critère industriel et des simulations effectuées sur un modèle non-linéaire de quart de véhicule
This work concerns the development of advanced control methods for automotive suspensions to improve road holding and passenger comfort, while satisfying the technological constraints related to the suspension actuators (passivity, nonlinearity, structural limit). In the first part, we propose two control schemes by polytopic LPV (Linear Parameter Varying) approach and by Strong Stabilization with genetic algorithm optimization to solve the comfort/handling and comfort/suspension travel conflits. In the second part, to solve the full semi-active suspension problem, we develop first a generic strategy for general LPV systems subject to actuator saturation and state constraints. The problem is studied in the form of resolution matrix of linear inequalities (LMI) that allows synthesizing an LPV controller and an anti-windup gain to ensure the stability and performance of the closed-loop system. Second, the theoretical result is applied to the case of semi-active suspension control. The proposed methods are validated by an evaluation based on an industrial standard and simulations on a nonlinear quarter vehicle model

12

Abdali, Saba. "Flyktens inverkan på kvinnors liv : En kvalitativ studie om hur kvinnliga flyktingar upplever att de kan forma sina liv i den svenska staten." Thesis, Uppsala universitet, Statsvetenskapliga institutionen, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-352361.

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The aim of this study is to examine how female refugees in Sweden experience that their escape and arrival to Sweden have formed their lives and wellbeing. The study seeks to understand how several women live their lives in relation to equality, discrimination and justice within the Swedish territorial borders. This is done with the Capability Approach by Martha C Nussbaum where she uses a list of universal values that should be central to women in every country, as a method of comparing how fair women live. I chose to interview six women who have fled to Sweden as refugees during the past 10 years, in order to see if the Capability Approach applies to them. I have also used Nancy Frasers theory of the scales of justice in my thesis. Fraser mentions three-dimensional politics where the inclusion of redistribution, recognition and representation should be achieved to create justice for women. The result showed that the women lack central capabilities such as the right to not being discriminated based on their ethnicity or religion, and the right to experience emotional development that is not bothered by traumatic experiences or unhealthy relationships. Furthermore, these women do not have the right to participate in political decisions that affect and shape their lives. The result in relation to Fraser’s theory indicates that these women have a limited freedom in Sweden. According to Fraser, there has to be an integration of a redistribution of resources, recognition, and a representation in Swedish politics, which benefit female refugees.

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Jaanson, Jenny. "Vardagens sociala liv för föräldrar till ett barn med psykossjukdom - fem föräldrars erfarenheter." Thesis, Linnéuniversitetet, Institutionen för socialt arbete, SA, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-13301.

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The purpose of this study was to describe experiences in daily social life of parents of children with psychotic illness. Five parents with long-term experience of psychotic illness have been interviewed. The frame of reference in emotion theories of Thomas Scheff and Randall Collins have been used to analyze the results. The study is qualitative and has a phenomenological approach to shed lights of meanings in daily social life. The following meanings was found: Openness with certain reservation shows that honesty is important for the feeling of solidarity, Social expectations in daily life describes the parents´own expectations as well as expectations from others. In The important confirmation the findings show that the parents´need understanding for the family situation, and the findings also show the importance of support for the family and the acceptance of the psychotic illness.

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Akram, Ghorbani. "Får jag lov att vara annorlunda? : en vetenskaplig essä." Thesis, Södertörns högskola, Institutionen för kultur och lärande, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-21875.

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Min essä handlar om en händelse som är självupplevd. Den beskriver att det finns brist på erfarenhet om interkulturellt förhållningssätt på vissa förskolor. Den beskriver även att jag och mina kollegor inte kunde hantera några situationer som man i förskolans värld kan hamna i. Dilemmat som framträder i händelsen handlar om brist på kunskap när det gäller interaktion mellan olika kulturer. Detta speciellt på de institutioner där den är som allra viktigast i samhället, nämligen i skolans- och förskolans värld. Uppsatsen visar det förhållningssätt som pedagoger har gentemot vuxna och barn, som i pedagogernas ögon anses vara annorlunda. Det här är en vetenskaplig essäform där mina egna erfarenheter möter olika teoretiska perspektiv. På det sättet försöker jag att nå svar på mina frågor men även lyfta fram dilemmat i min essä. Därför får den som läser möjlighet att se mina erfarenheter ur nya perspektiv. Jag inleder min uppsats med att diskutera bristande interkulturellt ledarskap i förskolans miljö. Därefter utvecklas den med hjälp av teoretiska perspektiv, genom att lyfta fram hur vi kan bli bättre på att utveckla ett interkulturellt förhållningssätt. I mitt slutord reflekterar jag kring viktiga ämnen som essän har lyft fram med fokus på möjliga förbättringar. Det viktigaste ämnet i essän är det förhållningssätt som vi pedagoger har när det gäller barnens olikheter.

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Nguyen, Manh Quan. "LPV approaches for modelling and control of vehicle dynamics : application toa small car pilot plant with ER dampers." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAT091/document.

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La suspension joue un rôle central pour la dynamique verticale d’un véhicule automobile afin d’améliorer le confort des passagers et la tenue de route. Les travaux de recherche de cette thèse sont divisés en deux grandes parties. La première partie considère le problème de commande d’une suspension semi-active dont le défi principal est de prendre en compte les contraintes de dissipativité et de débattement maximum des amortisseurs. Celles-ci sont transformées en des contraintes sur la commande et l’état d‘un système linéaire. Deux approches sont alors proposées pour la synthèse de la commande de la suspension semi-active : la commande Linéaire à Paramètres Variants (LPV) avec prise en compte de la saturation et la Commande Prédictive à base de Modèle (MPC).La deuxième partie est consacrée à l’estimation de défaut actionneur et à la commande Tolérante à ce type de défauts, avec comme application majeure le système de suspension semi-active. On considère ici comme défaut une perte de puissance de l’amortisseur (par exemple une fuite de l’huile), qui est estimée en utilisant plusieurs approches fondées sur des observateurs d’état. Puis, en fonction de l’estimation du défaut, la commande en boucle fermée est reconfigurée afin de conserver des performances pour la dynamique verticale du véhicule
Semi-active suspension system plays a key role in enhancing comfort and road holding of vertical dynamics in automotive vehicles. This PhD thesis research work, focused on that topic, is divided into two main parts. The first one considers the semi-active suspension control problem, the main challenge of which being to handle the dissipativity constraint and suspensions stroke limitation of semi-active dampers. These constraints are recast into input and state constraints in a linear state space representation. Thereby, the semi-active suspension control is designed in the framework of Linear Parameter Varying (LPV) approach with input constraints, and of Model Predictive Control (MPC) approach.The second part is devoted to Fault Estimation and Fault Tolerant Control (FTC) in case of actuator fault, and its application to Semi-Active suspension systems. The fault considered here is the loss of actuator's efficiency (due to an oil leakage of the damper for instance when a ), which is estimated using several observer-based approaches. Then, thanks to the fault information from the estimation step, an LPV/FTC fault scheduling control is designed to limit the vehicle performance deterioration

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Do, Anh lam. "Approche LPV pour la commande robuste de la dynamique des véhicules : amélioration conjointe du confort et de la sécurité." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00822010.

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Ce travail concerne le développement de méthodes de commandes avancées pour les suspensions automobiles afin d'améliorer la tenue de route des véhicules et le confort des passagers, tout en respectant les contraintes technologiques liées aux actionneurs de suspension (passivité, non-linéarités, limite structurelle). Dans la 1ère partie, nous proposons deux schémas de commande par approche LPV polytopique (Linéaire à Paramètre Variant) et Stabilisation Forte (Strong Stabilization) avec optimisation par algorithme génétique pour résoudre les conflits confort/tenue de route et confort/débattement de suspension. Dans la 2ème partie, pour résoudre le problème complet de commande de suspensions semi-actives, nous développons d'abord une stratégie générique pour les systèmes LPV généraux soumis à la saturation des actionneurs et à des contraintes d'état. Le problème est étudié sous la forme de résolution d'inégalités linéaires matricielles (LMI) qui permettent de synthétiser un contrôleur LPV et un gain anti wind-up garantissant la stabilité et la performance du système en boucle fermée. Ensuite, cette stratégie est appliquée au cas de la commande des suspensions semi-actives. Les méthodes proposées sont validées par une évaluation basée sur un critère industriel et des simulations effectuées sur un modèle non-linéaire de quart de véhicule.

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Salameh, Jack. "Approche par contrôle actif dans le cadre de l'optimisation de la durée de vie des éoliennes." Thesis, La Rochelle, 2019. http://www.theses.fr/2019LAROS026.

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Cette thèse intitulée "Approche par contrôle actif dans le cadre de l'optimisation de la durée de vie des éoliennes » étudie le fonctionnement des éoliennes et vise à réduire les perturbations au moyen d'une stratégie de contrôle actif. Les éoliennes fonctionnent dans des conditions environnementales difficiles en raison de vitesses de vent aléatoires. Le profil du vent induit deux composantes de perturbation appelées cisaillement et ombre de la tour. Ces composants produisent un couple aérodynamique perturbé qui provoque des contraintes, de la fatigue et une défaillance des composants mécaniques. Le chapitre 1 introduit la théorie autour des éoliennes et tous les sous-systèmes mécaniques et électriques associés. Le filtre de Kalman étendu (EKF) est ensuite introduit pour évaluer la nécessité du traitement du signal et du diagnostic pour l'isolation et la détection des perturbations. Le chapitre 2 présente une nouvelle méthode modifiée de décomposition en mode empirique par fenêtre glissante (SWEMD) en tant que méthode de traitement du signal capable de mieux isoler les perturbations. On en conclut qu'après le SWEMD, on peut détecter la signature fréquentielle du cisaillement du vent et de l'ombre de la tour. Dans le chapitre 3, une méthode d'estimation basée sur l'observateur à entrée inconnue (UIO) est appliquée afin d'estimer la perturbation dans l'éolienne. L'UIO montre d'excellents résultats en estimant avec précision la perturbation. Le chapitre 4 présente la stratégie de contrôle actif basée sur un contrôleur linéaire à paramètres variants (LPV) dans le but d'atténuer les ondulations du couple aérodynamique. En fait, la perturbation isolée par le SWEMD et la perturbation estimée via l'UIO sont utilisées comme entrée de contrôle LPV afin de générer une référence de contrôle. La commande est ensuite injectée dans le générateur afin de réduire l'effet des perturbations. Tant pour l'isolation que pour l'estimation, les résultats montrent une bonne atténuation des perturbations aérodynamiques. On peut constater que l'UIO a montré des résultats supérieurs à ceux de la SWEMD. Le chapitre 5 présente le montage expérimental utilisé pour valider les travaux théoriques. Un banc d'essai de l'Université de Poitiers est utilisé pour imiter le fonctionnement de l'éolienne. Tous les résultats permettent la validation des techniques théoriques utilisées dans les simulations numériques
This thesis entitled "Active control for wind turbine lifetime expectancy optimization" studies the operation of wind turbines and aims to reduce disturbance through an active control strategy. Wind turbines are known to operate under harsh environmental conditions mainly related to random wind speeds. The wind profile induces two disturbance components known as the wind shear and tower shadow. These components produce a disturbed aerodynamic torque causing stress, fatigue, and mechanical component failure. Chapter 1 introduces the wind turbine theory and all related mechanical and electrical subsystem. The extended Kalman filter (EKF) is then introduced to show the necessity of signal processing and diagnosis for disturbance isolation and detection. Chapter 2 presents a new modified Sliding Window Empirical Mode Decomposition (SWEMD) method as a signal processing method capable of better isolating the disturbance component. It is concluded that after the SWEMD one can accurately diagnose the wind shear and tower shadow disturbance frequency signature. In chapter 3 an estimation method based on the Unknown Input Observer (UIO) is applied in order to estimate the disturbance in the wind turbine. The UIO shows great results in accurately estimating the disturbance. Chapter 4 introduces the active control Linear Parameter Varying (LPV)-based strategy for torque ripple attenuation. The isolated disturbance by the SWEMD, and the estimated disturbance through the UIO are used as the LPV control input in order to generate a current control command. The control command is then injected into the generator in order to reduce the disturbance effect on the drivetrain. For both isolation and estimation results show good aerodynamic disturbance attenuation, while the UIO showed better results than those of the SWEMD. Chapter 5 presents the experimental setup used to validate the theoretical work. A test bench at the University of Poitiers is used to imitate the operation of the wind turbine. All the results matched the ones found in the theoretical tests

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Tinard, Sophie. "Effets des connaissances sur les souvenirs épisodiques : approche comportementale et neurophysiologique." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0652/document.

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Les modèles à deux processus de la mémoire de reconnaissance postulent l’intervention de deux mécanismes indépendants, la familiarité et la récollection, là où les modèles à un processus envisagent un continuum. Aujourd’hui, les théories à deux processus sont les plus largement acceptées grâce à la découverte de deux composantes électrophysiologiques qui reflèteraient les processus de familiarité et de récollection, respectivement la FN400 et la LPC. Cependant, l’indépendance de ces deux composantes est sujette à débat. L’objectif principal de cette thèse a donc été d’examiner la nature de ces processus et de leurs corrélats neuronaux afin de tester leur indépendance. Pour ce faire, nous avons d’étudier l’influence des informations perceptives (études 1 et 2), sémantiques (études 1, 2, 3 et 4), associatives (études 1 et 2), ainsi que la répétition à l’encodage (étude 3), et l’effet de l’âge (étude 4), sur les processus de récollection, de familiarité et leurs corrélats respectifs en couplant les données ROC et EEG. Les résultats vont dans le sens d’une conception de la familiarité reflétée par la FN400 comme étant multi-déterminée et permettent de préciser le caractère conditionné et hiérarchique dans le traitement des informations : perceptives, sémantiques puis associatives. Nos données indiquent en revanche que la récollection et la LPC serait principalement influencée par des informations sémantiques et associatives et ensuite, dans un second temps, par des informations perceptives. Dans leur ensemble, ces résultats sont en faveur du modèle de redondance, suggérant que la familiarité et la récollection dépendent d’un processus commun, multi-déterminé et dynamique
Dual-process models of recognition postulate that two independent processes sustained recognition (familiarity and recollection) while single process models consider the familiarity and the recollection as the ends of a continuum reflecting a common process. For now, dual-process models are the most accepted, due to electrophysiological evidences of two distinct components, FN400 and LPC, which have been linked to familiarity and recollection, respectively. However, a debate is growing concerning the independence of these components. The main objective of this thesis was to investigate familiarity, recollection and their neural correlates’ nature. To this end, we studied the influence of perceptual (study 1 and 2), semantic (all study), associative information (study 1 and 2), the repetition (study 3) and the age-related effect (study 4) on familiarity, recollection and corresponding neural correlates using ROC and EEG data. Results support the view that familiarity, as reflected by FN400, is multi-determined but allow to specify the conditioned the hierarchy in the information’s processing: perceptual then semantic and then associative. Recollection, as reflected by the LPC, would also be multi-determined, but was mainly influenced by semantic and associative information and then, in a secondary way, by perceptual information. Taken together, present data support the redundancy model suggesting that familiarity and recollection depend on a common, multi-determined and dynamic process

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Yang, Dapeng. "Approche algébrique pour l’analyse de systèmes modélisés par bond graph." Thesis, Ecole centrale de Lille, 2012. http://www.theses.fr/2012ECLI0007/document.

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La commande de systèmes physiques s’avère être une tâche difficile en général. En fonction du modèle choisi, les outils mathématiques pour l’analyse et la conception de lois de commande peuvent changés. Pour les systèmes décrits par une représentation entrée-sortie, type transfert, ou par une équation de type état, les principales informations exploitées lors de la phase d’analyse concerne la structure interne du modèle (structure finie) et la structure externe (structure à l’infini) qui permettent avant la phase de synthèse de connaître, sur le modèle en boucle ouverte, les propriétés des lois de commande envisagées ainsi que les propriétés du système piloté (stabilité…).Le travail porte principalement sur l’étude des zéros invariants des systèmes physiques représentés par bond graph, en particulier dans un contexte de modèle type LTV. L’approche algébrique est essentielle dans ce contexte car même si les aspects graphiques restent très proches du cas linéaire classique, l’extension aux modèles LTV reste très complexe d’un point de vue mathématique, en particulier pour le calcul de racines de polynômes. De nouvelles techniques d’analyse des zéros invariants utilisant conjointement l’approche bond graph (exploitation de la causalité) et l’approche algébriques ont permis de mettre en perspective certains modules associés à ces zéros invariants et de clarifier le problème d’annulation des grandeurs de sortie. L’application aux problèmes d’observateurs à entrées inconnues a permis d’illustrer nos propos sur des exemples physiques, avec certaines extensions, problèmes pour lesquels les zéros invariants apparaissent aussi comme éléments essentiels
The control synthesis of physical systems is a complex task because it requires the knowledge of a "good model" and according to the choice of a model some specific tools must be developed. These tools, mainly developed from a mathematical and theoretical point of view, must be used from the analysis step (analysis of model properties) to the control synthesis step. It is well-known that in many approaches, the properties of the controlled systems can be analyzed from the initial model. If the system is described with an input-output representation or with a state space representation, two kinds of information are often pointed out: the external structure (infinite structure) and the internal structure (finite structure). The first one is often related to the existence of some control strategies (input-output decoupling, disturbance decoupling...) and the second one gives some focus on the stability property of the controlled system.In this report, the focus has been on the study of invariant zeros of bond graph models in the context of LTV models. The algebraic approach was essential because, even if the problem is already solved for LTI bond graph models, the extension to LTV models is not so easy. The simultaneous use of algebraic and graphical approaches has been proven to be effective and convenient to solve this problem. First, some tools from the algebraic approach have been recalled in chapter one and results for the study of invariant zeros of LTI bond graph models recalled in chapter two. Some new developments are proposed in chapter three and some applications for the unknown input observer problem with some physical applications conclude this work

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Oudainia, Mohamed Radjeb. "Contrôle partagé adaptatif et élaboration de stratégies de conduite personnalisées pour le véhicule automatisé : une approche par apprentissage progressif." Electronic Thesis or Diss., Valenciennes, Université Polytechnique Hauts-de-France, 2023. http://www.theses.fr/2023UPHF0038.

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La conduite autonome suscite un intérêt croissant auprès les constructeurs, les chercheurs, les autorités et le grand public en raison de ses promesses en matière de sécurité routière, de mobilité pour les personnes âgées et à mobilité réduite, d'efficacité énergétique et de réduction des émissions. Cependant, le déploiement complet de ces véhicules dépend de leur fiabilité dans toutes les situations, ce qui nécessite une supervision du conducteur. Cela soulève des questions cruciales sur l'interaction homme-machine, en particulier en ce qui concerne le partage de la commande et la résolution des conflits.La thèse s'inscrit dans le cadre du projet ANR-CoCoVeIA (2019-2024) coordonné par le LAMIH (Coopération Conducteur-Véhicule Intelligent Autonome). Son objectif principal est d'incorporer des capacités d'auto-apprentissage dans les véhicules autonomes de niveau 2 pour améliorer leurs compétences en respectant les règles de sécurité routière. La thèse se concentre sur l'optimisation de l'interaction entre le système automatisé et le conducteur pour renforcer l'efficacité, améliorer les performances de conduite et favoriser l'acceptabilité du système.Pour atteindre ces objectifs, une architecture de coopération auto-adaptative à plusieurs niveaux est proposée dans la première partie de la thèse. Cette architecture vise à adapter de manière optimale le comportement du véhicule autonome à un style de conduite préféré des conducteurs tout en garantissant une conduite sécuritaire et efficace. Une deuxième partie de la thèse se penche sur la personnalisation des systèmes d'assistance au changement de voie, utilisant une approche d'apprentissage basée sur la descente de gradient stochastique pour ajuster les paramètres en fonction des préférences du conducteur, en se basant sur la détection de ses intentions de changement de voie.Pour résoudre les conflits entre le conducteur et le système de conduite autonome, la thèse explore trois approches de commande optimale robuste pour les systèmes linéaires à paramètres variants (LPV) représentés sous la forme floue Takagi-Sugeno (T-S). La première approche se concentre sur le contrôle partagé adaptatif en ajustant une fonction de coût multi-objectif en temps réel en fonction de la disponibilité du conducteur et de l'évaluation du risque. La deuxième approche introduit un modèle dynamique du conducteur, dont les paramètres sont identifiés en ligne, permettant une adaptation continue aux caractéristiques du conducteur. Ce modèle est utilisé pour développer un système de contrôle partagé adaptatif pour le maintien de voie en tenant compte de la dynamique des paramètres neuromusculaires du conducteur.La dernière approche vise à éliminer complètement les conflits entre le conducteur et le système de maintien de voie en combinant une fonction de coût adaptative avec un modèle dynamique du comportement du conducteur.Pour la conception du contrôleur partagé LPV, les conditions de stabilité en boucle fermée du contrôle partagé adaptatif (LPV) pour les trois approches sont établies à l'aide d'arguments de stabilité de Lyapunov et formulées sous forme d’un problème d’optimisation d’inégalités matricielles linéaires (LMI) qui peuvent être résolues numériquement grâce à des algorithmes d’optimisation convexe. Des validations expérimentales et des expériences de test utilisateur ont été menées au moyen du simulateur de conduite dynamique SHERPA-LAMIH pour évaluer l’acceptabilité de ces approches, démontrant ainsi leur efficacité pour améliorer la sécurité et le confort de conduite, et validant l’ensemble des approches proposées
Autonomous driving technology is attracting increasing interest from automobile manufacturers, researchers, authorities, and the general public due to its promises in enhancing road safety, providing mobility for the elderly and individuals with reduced mobility, improving energy efficiency, and reducing emissions. However, the full deployment of these vehicles relies on their reliability in all situations, necessitating driver supervision. This raises critical questions about human-machine interaction, particularly concerning sharing control between the automated driving system and the driver, as well as conflict management.The thesis is part of the ANR-CoCoVeIA project (2019-2024), coordinated by LAMIH (Cooperation Driver-Autonomous Intelligent Vehicle). The main objective of this project is to introduce self-learning capabilities into level 2 autonomous vehicles to enhance their skills while adhering to road safety rules. The thesis focuses specifically on managing interactions between the automated system and the driver, with the goal of improving its effectiveness, enhancing driving performance, and promoting the driver's acceptance of the system.To achieve these goals, a multi-level evolutionary cooperation architecture is proposed in the first part of the thesis. This architecture aims to optimally adapt the behavior of the autonomous vehicle to a driver's preferred driving style while ensuring safe and efficient driving. The second part of the thesis delves into personalizing lane change assistance systems, using a stochastic gradient descent-based learning approach to adjust parameters based on the driver's preferences, relying on the detection of their lane change intentions.To address conflicts between the driver and the autonomous driving system, the thesis explores three robust optimal control approaches for linear time-varying parameter systems (LPV) represented in the Takagi-Sugeno (T-S) fuzzy form. The first approach focuses on adaptive shared control by real-time adjustment of a multi-objective cost function based on driver availability and risk assessment. The second approach introduces a driver's dynamic model, with parameters identified online, allowing continuous adaptation to the driver's characteristics. This model is used to develop an adaptive shared control system for lane-keeping, taking into account the neuromuscular dynamics of the driver's parameters. The final approach aims to entirely eliminate conflicts between the driver and the lane-keeping system by combining an adaptive cost function with a dynamic driver behavior model.For the design of the LPV shared controller, stability conditions for closed-loop adaptive shared control (LPV) for all three approaches are established using Lyapunov stability arguments and formulated as a linear matrix inequality (LMI) optimization problem that can be numerically solved using convex optimization algorithms. Experimental validations and user testing experiments were conducted using the SHERPA-LAMIH dynamic driving simulator to assess the acceptability of these approaches, demonstrating their effectiveness in improving safety and driving comfort and validating all of the proposed approaches

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Nilsson, Jonas, and Tommy Regin. "Frågan om den samhällsnyttiga medborgaren : En analys av diskursen i utredningarna som föregick Lgy 70 och Lpf 94." Thesis, Linnéuniversitetet, Institutionen för pedagogik (PED), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-31870.

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Uppsatsen syftade till att undersöka skolpolitiken som låg till grund för Lgy 70 och Lpf 94. Specifikt fokus låg på att i utredningsmaterialet undersöka politikens styrande effekter genom att utifrån argumenten blottlägga dess människo- och kunskapssyn. Metoden som har använts var Carol Lee Bacchis What’s the problem represented to be?-approach. I uppsatsen har en analys av diskursen genomförts på det material som ligger till grund för de nämnda läroplanerna. Undersökningen har funnit att den övergripande problemtiken gällande gymnasieskolorna var att gymnasiet framställdes som omodernt och icke-anpassningsbart till samhället. Dock var det en specifik grupp elever som utgjorde problemet och som skolan var tvungen att anpassas till. Gruppen varierade mellan de olika tidsperioderna, men innefattade dem som inte klarade av skolan i dess dåvarande form. Lösningarna på den av utredningarna antagna problematiken riktades oftast mot den här gruppen och medförde att elevernas valfrihet ökades. Denna valfrihet var dock en strategi som staten använde för att styra in eleverna mot en av staten sedd ”rätt” utbildning. Den underliggande människo- och kunskapssynen i samtliga utredningar var behavioristisk. Utredningarna antog att ungdomarna till stor del påverkades av sin bakgrund och sociala klass i valet av utbildning. Slutsatser som dras är att gymnasieskolan anpassas för arbetsmarknadens behov. Utbildning anses göra ungdomarna mer kvalificerade för yrkesverksamhet. För dem som inte klarar av detta måste skolan anpassas. Således reformerades gymnasieskolan efter de lågpresterande eleverna.
The purpose of this paper was to examine the Swedish school policies that formed the basis for the curriculums Lgy 70 and Lpf 94. Specific focus was on finding the governing effects in the exanimated material by extracting its view on humans and knowledge. The method used was Carol Lee Bacchi’s What’s the problem represented to be?-approach. With this method authors conducted an analysis of the discourse in the material. The investigation of the material found that the overall problem concerning the Upper secondary school was their portrayal as outdated and non-adaptive to the society of that time. However, a group of students were represented to be the problem to which the school needed to adapt. The content of the group differed between the two time-periods (the 1960s and the 1990s), but the group included those who were not capable of managing the school of that time. The solutions to the, by the investigations assumed problem, were directed towards this group of student and resulted in an increased freedom of choice for them. This freedom of choice was however a control strategy used by the government to direct student towards a, by the government considered, “proper” education. The underlying view of humans and knowledge was a behavioural one. The exanimated investigations assumed that young people were largely influenced by their background and social class in their choice of education. In conclusion the Swedish upper secondary school were adapted to the demands of the labour market. Education was considered to make the students more qualified for their future life as workers. The school needed to adapt to those who were not capable of this.

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Wahlberg, Elisabeth. ""... och så har jag ju alltid morsan som kan hjälpa mig" : Om unga vuxnas strategier för att hantera sina läs- och skrivsvårigheter i dagligt liv." Thesis, Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-12993.

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Author: Elisabeth Wahlberg Title: “…I’ll just get mum to help me” About Young Adults’ Strategies for Coping with Reading and Writing Difficulties in Daily Life This study investigated how seven young adults, who during senior high school underwent a syllable based intervention due to reading and writing difficulties, developed their literacy skills, and what strategies they used to try to overcome reading and writing problems, whether at work, during studies or in their leisure time. The period from when the participants had left school ranged between three and eight years. Qualitative as well as quantitative data was compiled for the study. Qualitative data consisted of semistructured interviews and quantitative data of tests performed before the intervention and on two occasions after, in order to compare results over time. The study was a longitudinal case study with a phenomenological lifeworld approach and looked to increase awareness of the realities of living with reading and writing difficulties. It analysed how the participants dealt with their problems and what strategies they employed, in order to overcome them. Study results showed that even as participants improved their literacy skills compared to pre-intervention, reading and writing remained an issue. All participants were forced to adjust to the fact that they were affected in their daily lives, whether in choice of career or further education, or more everyday tasks involving reading and writing and also the inclination to read for pleasure. They avoided to expose their shortcomings if at all possible. Still, the participants all strived to tackle their reading and writing problems by applying elements from the syllable based intervention in conjunction with inventing individual strategies.

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Effeney, Gerard. "A case study investigating changes in students' approaches to learning when exposed to teaching strategies aimed at promoting metacognitive learning." Thesis, Australian Catholic University, 1994. https://acuresearchbank.acu.edu.au/download/6d64d83151bea85db890d23c64cf0cb43a9ac7d318709726568675bd8e466abb/6376502/Effeney_1994_A_case_study_investigating_changes_in.pdf.

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The purpose of this study was to investigate, through the use of case study approach, changes in students' approaches to learning when exposed to teaching strategies aimed at promoting metacognitive learning. The case study approach used in this research to address the research question was characterised by three stages: - Identification of the initial learning characteristics of the students. - Identification of any changes in these learning characteristics following the exposure to teaching strategies aimed at promoting metacognitive learning. - Monitoring the students’ perceptions of their own learning during this time using a variety of data sources. Stages one and two were firstly applied to the class as a group, and provided a framework within which the more detailed investigation of the individual case studies were situated. The use of the Learning Process Questionnaire (LPQ) as a means of identifying the general learning characteristics of the students was successful. The approach to learning identified by the LPQ for an individual student was very often confirmed by the other data sources. A second application of the LPQ did uncover changes in individual student’s approaches to learning, which, through student reflection sheets, semi-structured interviews and teacher reflection, were able to be investigated further. The results seemed to indicate that in some cases, these changes in approaches were influenced by the teaching strategies used, but the extent to which metacognitive motives and strategies were adopted depended very much on their acceptance of the class and the individual students.

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Andaloussi, Chafik. "Propriétés structurelles des systèmes linéaires à paramètres variant dans le temps : approche bond-graph." Ecole Centrale de Lille, 2007. http://www.theses.fr/2007ECLI0004.

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Cette thèse étudie des propriétés structurelles sur les modèles bond graphs. La motivation principale est de contribuer à la résolution des problèmes liés à l’étude des propriétés structurelles et au calcul du système inverse d’un système LTV à l’aide de l’utilisation des propriétés et des avantages offerts par une représentation graphique telle que le bond graph. Cette problématique est abordée dans le cas de modèles bond graphs linéaires à paramètres variant dans le temps et des outils adéquats ont été proposés. De nouveaux concepts ont été introduits : en définissant la notion d’anneau bond graph non commutatif, une nouvelle règle de gain ou "règle de Riegle" est introduite en bond graph. Grâce à l’introduction de la notion de l’algèbre différentielle et à l’aide des opérateurs (delta et sigma), il est possible de calculer graphiquement les termes des matrices de commandabilité/observabilité en utilisant des règles adéquates basées sur le calcul de la longueur des chemins causaux entrées-états/états-sorties. Il est aussi montré que les règles graphiques de l’étude de la structure à l’infini restent applicables dans un anneau bond-graph. Pour aller plus loin dans l’introduction de l’outil d’algèbre différentielle aux bond graphs, l’étude des propriétés d’inversibilité d’un modèle anneau bond-graph a été abordée. Dans ce contexte et grâce à la notion des chemins causaux entrées-sorties disjoints, il est possible de faire une analyse de l’inversibilité directement à partir de son modèle BG. Il est également montré que la notion de bicausalité et l’obtention graphique de la paramétrisation différentielle en utilisant la règle de Riegle est rendue possible
This thesis aims at the study of the structural properties on the bond-graph models. The principal motivation is to contribute to the resolution of the problems related on the study of the structural properties and calculation of the inverse system of a LTV system using of the properties and the advantages offered by a graphical representation such as the bond-graph. These problems are approached in the case of linear bond-graphs models with time varying parameters and the adequate tools were proposed. To achieve these goals, new concepts and tools were introduced. In particular, defining the concept of noncommutative bond-graph ring, a new gain rule known under the name of “Riegle rule” is introduced in bond-graph. In addition, thanks to the introduction of the notion of the differential algebra and using of the operators (delta and sigma), it became possible to graphically calculate the terms of the matrices of commandability/observability by using appropriate rules based on calculation length of the causal paths inputs-states/states-outputs. It is also shown that the graphic rules of the study of the infinite structure remain applicable in a bond-graph ring. Finally, to go further in the introduction of the algebra tool and modules to the bond-graphs, the study of the properties of inversibility of a bond-graph ring model was approached. In this context and basing on the disjoint input-output causal paths notion, it is possible to make an analysis of the inversibility directly from its BG model. It is also shown that the bicausality concept and graphic determination of the differential parameterization by using the rule of Riegle are made possible

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Yang, Dapeng. "Approche algébrique pour l'analyse de systèmes modélisés par bond graph." Phd thesis, Ecole Centrale de Lille, 2012. http://tel.archives-ouvertes.fr/tel-00735082.

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La commande de systèmes physiques s'avère être une tâche difficile en général. En fonction du modèle choisi, les outils mathématiques pour l'analyse et la conception de lois de commande peuvent changés. Pour les systèmes décrits par une représentation entrée-sortie, type transfert, ou par une équation de type état, les principales informations exploitées lors de la phase d'analyse concerne la structure interne du modèle (structure finie) et la structure externe (structure à l'infini) qui permettent avant la phase de synthèse de connaître, sur le modèle en boucle ouverte, les propriétés des lois de commande envisagées ainsi que les propriétés du système piloté (stabilité...).Le travail porte principalement sur l'étude des zéros invariants des systèmes physiques représentés par bond graph, en particulier dans un contexte de modèle type LTV. L'approche algébrique est essentielle dans ce contexte car même si les aspects graphiques restent très proches du cas linéaire classique, l'extension aux modèles LTV reste très complexe d'un point de vue mathématique, en particulier pour le calcul de racines de polynômes. De nouvelles techniques d'analyse des zéros invariants utilisant conjointement l'approche bond graph (exploitation de la causalité) et l'approche algébriques ont permis de mettre en perspective certains modules associés à ces zéros invariants et de clarifier le problème d'annulation des grandeurs de sortie. L'application aux problèmes d'observateurs à entrées inconnues a permis d'illustrer nos propos sur des exemples physiques, avec certaines extensions, problèmes pour lesquels les zéros invariants apparaissent aussi comme éléments essentiels.

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Schwudke, Dominik. "Biochemical and genetic approaches for the characterization of Bdellovibrionaceae, unique predatory bacteria." Doctoral thesis, [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=970402368.

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Chalh, Zakaria. "Approche algébrique et graphique pour l'analyse des modèles Bond Graph." Ecole Centrale de Lille, 2008. http://www.theses.fr/2008ECLI0002.

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L'objectif de ce mémoire est l'étude des propriétés structurelles des systèmes dynamiques linéaires à paramètres variants dans le temps à partir de leur modèle bond graph et leur module équivalent. Après un rappel succinct de la théorie des modules et les propriétés structurelles des systèmes LTI par l'approche bond graph, les différentes méthodes utilisées pour l'étude des propriétés structurelles ainsi que leur interprétation par la théorie des modules, une comparaison entre les deux approches est proposée. Pour atteindre ces objectifs, nous avons utilisé des outils et des concepts tels que la notion d'anneau bond graph non commutatif, le principe de la dualité sur les systèmes linéaires à paramètres variants dans le temps et la bicausalité. Grace à ces concepts nous avons introduits de nouvelles méthodologies. En particulier, une nouvelle règle graphique de calcul des éléments de la matrice de commandabilité et d'observabilité, le calcul de la partie non commandable qui représente le sous module de torsion du module équivalent au système, et à l'aide du principe de dualité nous déduisons la partie non observable à partir du calcul de la partie non commandable du système dual. Nous proposons une méthode graphique de calcul formel des zéros invariants des systèmes LTV en utilisant le principe de la bicausalité ce qui nous permet d'appliquer certains contraintes. La détermination de la partie non commandable et non observable nous aide à déterminer les zéros de découplage en entrée et en sortie
The objective of this dissertation is to study the structural properties of linear time varying dynamic systems from their bond graph model and their equivalent module. After a brief reminder of the theory of modules and structural properties of systems by LTI bond graph approach, the various methods used to study the structural properties and their interpretation by the theory of modules, a comparison between the two approaches is proposed. To achieve these objectives, we used tools and concepts such as the notion of ring non-commutative bond graph, the principle of duality on linear time varying systems and bicausality. Thanks to these concepts we have introduced new methodologies. In particular, a new graphic rule for calculating the elements of the controllability and observability matrix, the calculation of the non ordered representing the torsion sub-module of the system equivalent torsion module, and with the principle of duality we deduce the non-observable from the calculation of the non controllable part of the dual system. We propose a graphic method of formal calculation of the invariants zero of systems LTV by using the principle of the bicausality what enables us to apply certain constraints. The determination of the non-controlled and non-observable helps us determine the zeros decoupling inbound and outbound

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Stephens, Nathan Wallace. "A Comparison of Microarray Analyses: A Mixed Models Approach Versus the Significance Analysis of Microarrays." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/1115.

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DNA microarrays are a relatively new technology for assessing the expression levels of thousands of genes simultaneously. Researchers hope to find genes that are differentially expressed by hybridizing cDNA from known treatment sources with various genes spotted on the microarrays. The large number of tests involved in analyzing microarrays has raised new questions in multiple testing. Several approaches for identifying differentially expressed genes have been proposed. This paper considers two: (1) a mixed models approach, and (2) the Signiffcance Analysis of Microarrays.

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Ferrero, Frédéric. "Approche physio-pathologique et exploitation génétique de l'expression de la résistance à l'oïdium (sphaerotheca pannosa lev. , var. Rosae) dans le genre Rosa." Avignon, 2005. http://www.theses.fr/2005AVIG0314.

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L'oïdium du rosier est une maladie fongique foliaire, à lourdes conséquences économiques, provoquée par Sphaerotheca pannosa var. Rosae qui se développe sur l'hôte sans entraîner sa mort. Ce travail de thèse rapporte une étude en 4 étapes des relations hôte-parasite : 1- L'évaluation de l'expression des symptômes d'oïdium, dans une collection d'espèces botaniques et une de rosiers modernes. Elle a permis d'identifier des génotypes résistants. 2- Un programme de croisements pour évaluer la transmission de la résistance et les aptitudes à la combinaison. L'observation des ségrégations, sur les descendances d'un plan de croisement diallèle entre espèces 2x, a confirmé que le caractère de résistance était gouverné par plusieurs gènes. La démarche d'introgression de résistance, via un dihaploïde 2x de rosier moderne 4x, croisé avec R. Wichuraïana 2x, suivie de croisements frères–sœurs, s'est imposée pour fixer le caractère. 3- La recherche d'outils de criblage. Celle-ci a conduit à un test biologique d'évaluation de la résistance à l'oïdium et à des méthodes d'isolation et de maintien d'inoculum monoconidial. 4- L'étude de l'installation de la cuticule foliaire et de son efficience suivant : génotype, âge de l'organe et conditions d'environnement. Une méthodologie a été établie pour moduler l'installation de la cuticule sur des plantules issues d'in vitro. L'évapotranspiration cuticulaire de génotypes résistants a été mesurée inférieure à celle de sensibles. Enfin, une nutrition élevée en calcium activerait l'installation de la cuticule. En conclusion, l'ensemble de ces résultats contribue à la connaissance de la maladie et à la définition d'une stratégie pour la sélection du caractère de Résistance à l'oïdium
Powdery mildew of the rose tree induces heavy economic consequences. This disease is due to an external fungus Sphaerotheca pannosa var. Rosae that develops on the host without resulting in his death. This work of thesis points out a study in four steps of the relations host-parasite : 1- the evaluation of the expression of the symptoms of powdery mildew, in two collections, one of botanical species and another of modern rose trees. This approach allowed to identify resistant genotypes. 2- a program of crossings to evaluate the transmission of resistance and abilities for combination. The observation of the segregations, on the progenies from a diallele crossing plan between diploid species, confirmed that the character of resistance was controlled by several genes. The process for introgression of resistance, via a dihaploïd (2x) of modern rose tree (4x) cross with R. Wichuraïana (2x) followed with serial brother-sister crossings revealed as essential to fix the character. 3- the search for tools of sifting. This one led to a biological test of evaluation of resistance to powdery mildew and to methods for the isolation of the inoculum and following for the obtainment of mono-conidial isolates. 4- the study of the installation of the foliar cuticle and its efficiency according to : genotype, age of the organ and environmental conditions. A process was established to modulate the installation of the cuticle on plantlets resulting from in vitro. The cuticular evapotranspiration of resistant genotypes was measured lower than that of sensitive. At last, high calcium level in the nutrition of rose tree would activate the biosynthesis of the cuticle. In conclusion, the whole of these results contributes to the knowledge of the disease and to the definition of a strategy for the selection of the character of Resistance to powdery mildew

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Gallab, Maryam. "Développement d’une approche d’aide à la maitrise des risques dans les activités de maintenance d'une chaine logistique : Approche par modélisation et simulation basée sur les systèmes multi-agents." Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEM028/document.

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Cette thèse a pour objectif principal de développer un simulateur multi-agents pour concevoir un système d'aide à la maitrise des risques des activités de maintenance. Le but est d'explorer la complexité de la maintenance et de spécifier les interactions entre la fonction maintenance, l'analyse et l'évaluation des risques. Nous nous intéressons d’une part, à concevoir un modèle systémique permettant d’identifier et de modéliser un système industriel, à montrer les différentes interactions entre ses éléments, à analyser et évaluer les risques des activités de maintenance. Nous proposons la méthode MOSAR et le langage UML pour concevoir un modèle cognitif de référence. Ce modèle a servi de point de départ pour la conception d’une base de données à l’aide du langage SQL, qui est exploitée par le modèle Multi-Agents afin d’acquérir les informations nécessaires à son fonctionnement.D’autre part, nous développons une architecture d’un Système Multi-Agents qui a pour vocation d’anticiper les situations de défaillances et la prise de décisions à l’aide de la simulation du comportement du système étudié. Une comparaison entre les plateformes existantes dédiées aux Systèmes Multi-Agents est effectuée pour choisir la plateforme adéquate à notre problématique pour la réalisation de la simulation.Finalement, les modèles développés sont appliqués dans le cadre d’une chaîne logistique pour le chargement et le déchargement de GPL (Gaz de Pétrole Liquéfié). Un simulateur a été développé à l’aide de la plateforme AnyLogic dans le but d’étudier le comportement du système et de simuler les scénarios de défaillances choisis par l’industriel pour le calcul de la criticité à partir de trois paramètres (fréquence, gravité, détectabilité) et l’obtention d’un Tableau de Bord contenant un ensemble d’indicateurs de performance de la maintenance. Les modèles de simulation proposés permettent d’orienter les industries vers les bonnes décisions pour éviter les situations à risques pouvant déclencher des événements perturbateurs dommageables
The main objective of this thesis is to develop a multi-agent approach to designing a model to overcome risks of maintenance activities. The aim is to explore the maintenance complexity and to indicate the interactions between the maintenance function and the risk assessment.Firstly, we are interested in designing a systemic model to identify and model the industrial system, to show the different interactions between its elements, to analyze and to evaluate risks of maintenance activities. We propose the MOSAR method and the UML language to design a cognitive reference model. This model served as a starting point for designing a database using the SQL language, which is operated by Multi-Agent model to acquire the necessary information for its operation.On the other hand, we develop a framework of a multi-agent system that aims to anticipate failures scenarios and the decision-making by simulating the studied system behaviour. A comparison between the existing platforms dedicated to Multi-Agent Systems is performed to choose the appropriate platform for the simulation.Finally, the developed models are applied in the LPG supply chain (Liquefied Petroleum Gas). A simulator was developed using the AnyLogic platform in order to study the system behaviour and to simulate the failure scenarios chosen by the industry, for the calculation of the criticality from three parameters (Frequency, severity, detectability), and for obtaining a Dashboard containing a set of maintenance performance indicators. The proposed simulation models help to guide the industries toward good decisions to avoid risky situations that may trigger disruptive events damaging

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Rohaut, Benjamin. "Relations entre conscience et représentations sémantiques verbales : approche comportementale et neurophysiologique chez le sujet sain et le patient cérébro-lésé." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066413/document.

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L'étude de fonctions cognitives telles que le langage, la conscience et a fortiori leurs relations, constitue un défi aux confins de la médecine et des neurosciences cognitives. Le traitement sémantique procure à nos expériences perceptuelles un niveau de représentation abstrait, permettant une variété de fonctions conceptuelles. Dans ce travail, nous avons voulu explorer les relations entre le traitement sémantique verbal et la conscience en adoptant une double approche : d'une part en étudiant des sujets sains en condition de perception consciente et inconsciente (en utilisant une technique de masquage visuel), et d'autre part en étudiant des patients présentant un trouble de la conscience. Au travers de ce travail, nous apportons des arguments en faveur de l'existence de représentations sémantiques verbales inconscientes. Nous proposons également que les deux signatures cérébrales observées en potentiels évoqués (N400 puis LPC/P600) puissent s'intégrer dans un modèle à deux temps : premier temps inconscient (correspondant à la N400), puis second temps conscient (correspondant à la LPC/P600). En explorant les différences entre traitement conscient et non conscient, nous montrons que le traitement sémantique non conscient est sensible aux influences descendantes conscientes, ce qui réfute une conception strictement automatique de la cognition inconsciente. Nos résultats apportent également un nouveau regard sur les mécanismes de résolution d'ambiguïté sémantique. L'exploration des capacités cognitives telles que le traitement sémantique verbal, chez des patients présentant un trouble de la conscience, devrait permettre des avancées notables dans leur prise en charge
The study of cognitive functions so complex such as language and consciousness, and of their interactions, is a challenge at the boundaries between medicine (intensive care, anesthesia, neurology) and cognitive neuroscience. Semantic processing provides our perceptual experiences with a level of abstraction allowing a variety of conceptual functions such as object recognition, social cognition, or language. In this thesis, we explored the relationships between verbal semantic processing and consciousness using a double approach: first, by studying healthy subjects in conscious and unconscious condition (using visual masking), and secondly by studying patients with disorders of consciousness. Through this work we provided empirical evidence of unconscious semantic representations. We then proposed that the two main brain signatures of semantic processing observed in ERPs (N400 and LPC / P600) could be integrated in a two stages model: a first unconscious stage (corresponding to the N400), followed or not by a second stage of processing corresponding to conscious semantics (LPC / P600). Exploring the differences between conscious and nonconscious processing, we showed that nonconscious semantic processing is sensitive to conscious top-down influences. These results refute a strictly automatic conception of unconscious cognition. Our results also shed new light on the respective roles of the two hemispheres in the resolution of semantic ambiguity. The exploration of high-level cognitive abilities, - such a verbal semantic processing - in patients affected with disorder of consciousness should enable significant advancements in their medical management

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Raab, Raphaelle. "Vers une pédagogie des temps faibles : étude sur les processus d'autonomisation en classe maternelle dans le cadre des espaces-temps intersticiels." Thesis, Lyon 2, 2015. http://www.theses.fr/2015LYO20046/document.

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Notre thèse étudie les conditions favorables à l’autonomisation scolaire des élèves. L’étude empirique est menée en grande section de maternelle. Dans la plupart des situations de formation, les temps « d'autonomie » sont structurellement inévitables puisque le formateur ne peut être présent pour tous à chaque instant. Nous nous intéressons aux temps de classe au cours desquels l’enseignant n’intervient pas directement, soit parce qu’il n’est pas disponible, soit parce qu’il se retire volontairement de la situation. Nous les appelons temps faibles en raison de cette faible présence de l’enseignant : l’élève doit agir en fonction de ses propres forces, sans l’intervention directe du maître pour réguler l’apprentissage et les comportements. Il appert que les élèves n’y sont pas naturellement autonomes : laissées au hasard de capacités acquises hors l’école, les activités dites « en autonomie » contribuent à creuser les écarts entre les élèves face aux savoirs qui leurs sont proposés. L’autonomie ferait partie de ces comportements implicitement attendus et « davantage supposés ou requis par les enseignants que construits dans, avec et par l’école ». Comment penser le processus d’autonomisation scolaire et comment l’opérationnaliser en contexte ordinaire de classe ? Nous cherchons les outils, les leviers, les interactions et les dispositifs qui permettraient aux élèves, – à tous les élèves – de profiter des temps faibles au bénéfice de leurs apprentissages. Les données sont recueillies dans 14 classes sur 117 demi-journées d’observation directe, puis traitées à l’aide de l’analyse par les catégories conceptualisantes (Paillé, 2012). Dans la perspective (socio)constructiviste de l’apprentissage, pour construire un savoir nouveau, l’élève doit rencontrer un obstacle dans la réalisation de la tâche, l’apprentissage résultant du dépassement de celui-ci. Nous relevons des comportements différenciés face à l’obstacle dans les ateliers en autonomie : certains élèves entrent dans des conduites d’évitement, refusant d’affronter cet obstacle, s’en trouvant détournés en amont ou bien le contournant. D’autres, au contraire, entrent dans des conduites de ressources pour le dépasser et construire de nouvelles connaissances. En cours d’étude apparaissent des dynamiques remarquables : certains élèves, d’habitude « évitants », rejoignent ou se maintiennent parfois dans des conduites de ressources. L’étude de ces « exceptions notables » fait émerger les conditions favorables ayant permis leur dynamique particulière en termes d’outils, d’activités, d’interactions et de dispositifs. Ce qui aura pu fonctionner au bénéfice des exceptions notables pourrait être exploité comme levier pédagogique durable au bénéfice de tous. Ces conditions deviennent alors supposées favorables et sont réinvesties dans des dispositifs expérimentaux afin d’observer si elles produisent les effets attendus, dans quelle mesure et selon quelles limites (analyse des dispositifs expérimentaux par une adaptation du modèle systémique d’Engeström, 1987). Il apparait clairement que le processus d’autonomisation, en contexte scolaire de classe hétérogène et nombreuse, s’observe et se construit de façon privilégiée dans les temps faibles de la structuration pédagogique et leur articulation avec les temps forts, notamment les retours collectifs sur ateliers. Une pédagogie des temps faibles supposerait que soit accordé à ceux-ci un véritable statut pédagogique, en tant qu’étape et instrument essentiels au processus d’autonomisation scolaire. Une telle pédagogie supposerait également d’organiser avec soin les interventions de l’enseignant en mode opératoire indirect, au travers d’un dispositif de classe qui le relaie et dont les différentes dispositions (outils, règles, activités, interactions) peuvent « être appropriées » par l’élève comme instruments psychologiques pour agir sur lui-même, en première personne.
This dissertation studies favorable conditions to empowerment of pupils. The empirical study was carried out in the final year of kindergarten. In most learning/teaching situations, "autonomy moments" are structurally inevitable since the teacher cannot be systematically available to everyone all the time. Interest is focused on moments during which the teacher does not directly intervene, either because he/she is not available or because he/she voluntarily withdraws from the learning situation. We call these moments "low times" because of the teacher's low presence: during these specific moments, each student responds according to his own strengths without the teacher's direct intervention to regulate both learning and behavior. It appears that students are not naturally autonomous: when left unattended, the so-called "autonomous" learning activities contribute to widening the knowledge gap between students in learning situations. Autonomy would be part of this implicitly expected behavior and is "all the more expected and required from teachers rather than being constructed in, with and by school". How can student empowerment be perceived and operationalized in an ordinary class context? Our goal is to identify tools, levers, interactions and devices which enable students to benefit from "low times" for their own learning. The data are collected in 14 classes in 117 half-days of direct observation. Socio-constructivist approach to learning suggests that in order to construct new knowledge, the student must encounter an obstacle in the course of accomplishing his task. Learning results from overcoming this obstacle. We highlight differentiated behaviors of students when facing obstacles in autonomy classroom workshops: some resort to avoidance strategies and refuse to deal with this obstacle by bypassing or circumventing it. Conversely, others draw on (their own) resources in order to overcome it and construct new knowledge. During the study period, remarkable dynamics appear: some students, with usually an "avoidant" attitude, join or maintain a "drawing on resource conduct". The study of the "notable exceptions" leads to the emergence of the favorable conditions which fostered this particular dynamic in terms of tools, activities, interactions and devices. What would have worked to the benefit of the notable exceptions could be further used as a sustainable and pedagogical lever to the benefit of all students. These conditions become then supposedly favorable and are reinvested in experimental devices in order to see if they produce the expected effects, to which extent and within what limits? Il clearly appears that the empowerment process, in classroom context of a large and heterogeneous class, is developed in a special way in "low times" of pedagogical structuration and their articulation with "strong times", notably collective feedbacks on workshops. A pedagogy of "low times" entails providing the teacher with substantial pedagogical status, which would be a crucial step as well as an instrument in the school empowerment process. Such pedagogy would also entail carefully organizing teacher's intervention in an indirect mode, through a class device which would relay it through its various dispositions (tools, rules, activities, interactions). The student would then internalize these dispositions as psychological instruments in referring to oneself in the first person. This pedagogy would finally entail a redefinition of teacher's role: his/her apparent "absence" from the situation which would paradoxically become, a teaching-learning tool to the benefit of school empowerment

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Beckman, Bradley. "Ronald Stevenson's Passacaglia on DSCH: Understanding the Composer's Unique Approach to Large-Scaled Structure, a Lecture Recital, together with Three Recitals of Selected Works of L.V. Beethoven, J. Brahms, F. Liszt, F. Mendelssohn, B. Bartók and Others." Thesis, University of North Texas, 1994. https://digital.library.unt.edu/ark:/67531/metadc279229/.

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This paper investigates Ronald Stevenson's unique treatment of large-scaled structure in his Passacaglia on D S C H. This piece's unusual eighty-minute length, use of traditional forms and unusual piano techniques, musical references to other cultures and a massive triple-fugue over a ground bass will be examined as they relate to its overall form. The elements of rhythm, melody/mode, harmony, counterpoint, piano techniques, and tonality are also used as means of highlighting many unifying elements of the piece which contribute to its overall cohesiveness. Tributes to other composers, among them Dimitry Shostakovich to whom the piece is dedicated, are discussed in addition to many references to world cultures and events which support Stevenson's views on what he terms world music. Rarely is a piece written that encompasses such a wide range of musical elements that possess the ability to engage an audience for an uninterrupted length of eighty-minutes. As of yet, an in-depth scholarly investigation of Stevenson's treatment of formal unity in this landmark piano work has not been done. This analysis reveals Stevenson's approach to composing in such a large form, as well as illustrating his mastery of variation, counterpoint and unending ingenuity for innovative piano techniques. The composer's background and philosophies are discussed as well as the major impact made on his compositional style by both Percy Grainger and Ferruccio Busoni.

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Huang, Botao. "Mécanismes de vieillissement de l'Assemblage-Membrane-Électrodes dans une pile à combustible de type PEM par approche expérimentale." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0268/document.

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Cette thèse a permis de mettre en évidence les mécanismes de vieillissement de la pile à combustible de type PEM lors de cyclages d'humidité de l'air et suite à la perforation de l'AME (Assemblage Membrane Electrodes). Premièrement, les mécanismes connus de dégradation des divers composants (membrane, catalyseur, support du catalyseur, GDL, plaques bipolaires et joints d'étanchéité) ont été présentés. Ensuite, les outils de diagnostic en-ligne (chronopotentiométrie, spectroscopie d'impédance, gestion de l'eau et analyse chimique de l'eau) et ceux hors-ligne (CV et LSV) ainsi que des analyses post-mortem (RMN, MET, MEB et DRX) ont été décrits. Expérimentalement, le cyclage en humidité de l'air a été effectué en mono-cellule de 25 cm2: le cyclage à forte humidité entraîne une perte significative de la surface électroactive du catalyseur; le cyclage à faible humidité favorise la perméation de l'hydrogène à travers la membrane. Le cyclage à faible humidité réalisé sur une pile de 100 cm2 a montré un mécanisme de dégradation différent de celui de la pile de 25 cm2: la perméation de l'hydrogène reste faible alors que la tension de la pile était de plus en plus fluctuante certainement du fait de la présence de volumes morts et de la rétention d'eau liquide dans la pile. L'effet de la perforation de l'AME a été étudié sur une pile de 100 cm2: la perforation par une punaise de 0,7 mm de diamètre ne génère qu'une légère augmentation de la perméation de l'hydrogène; la perforation par une punaise de 1,2 mm de diamètre entraîne une chute de tension et l'augmentation significative de la résistance de diffusion de l'oxygène due à la perméation importante de l'hydrogène
This thesis highlights the aging mechanisms of PEM Fuel Cell submitted to two main aging conditions: air relative humidity (RH) cycling, and MEA (Membrane Electrode Assembly) pinhole test of operation. First, the aging mechanisms of PEMFC main components (membrane, catalyst, carbon support, GDL, bipolar plates and gaskets), have been reviewed from the literature. Then the on-line diagnostic tools (chronopotentiometry, electrochemical impedance spectroscopy, water management and water analysis), off-line ones (cyclic voltammetry and linear sweep voltammetry) and post-mortem analyses (nuclear magnetic resonance, transmission electron microscopy, scanning electron microscopy and X-ray diffraction) have been described. Experimentally, the high and low air RH cycling runs have been carried out with a 25 cm2 single cell: the high air RH cycling run promoted serious loss of the ElectroChemical Surface Area (ECSA); the low air RH cycling run caused significant increase in hydrogen crossover. The low air RH cycling has been also performed with a 100 cm2 single cell and the aging mechanism was different from that of 25 cm2 cell: the hydrogen crossover remained very low but the fuel cell voltage exhibited strong fluctuations at the end of the run: this was attributed to the presence of dead volumes and liquid water retention within the cell. Finally, MEA pinhole effect has been investigated with a 100 cm2 single cell: the perforation by a 0.7 mm diameter pin promoted slight increase in the hydrogen crossover; the perforation by a 1.2 mm diameter pin caused significant cell voltage losses and serious increase in the cathode diffusion resistance due to significant hydrogen crossover

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Carneiro, Maria Sylvia Cardoso. "Deficiência mental como produção social : uma discussão a partir de histórias de vida de adultos com síndrome de Down." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/10829.

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O presente trabalho apresenta uma pesquisa cujo objetivo central é discutir a deficiência mental como condição que se desenvolve a partir das relações sociais estabelecidas com sujeitos que apresentam características singulares em relação à maioria da população e não como uma incapacidade própria. Esta visão contraria as concepções tradicionais de deficiência mental e apóia-se na abordagem histórico-cultural, especialmente nas contribuições de Vigotski. A idéia-base é que, mesmo diante de qualquer alteração orgânica, ainda que esta seja em nível estrutural ou funcional do sistema nervoso, é pelas e nas relações sociais que o sujeito se desenvolverá, ou não, como deficiente mental. Como estratégia metodológica, foram utilizados relatos de histórias de vida de três adultos com síndrome de Down que se constituíram como sujeitos sem deficiência mental. Os três se escolarizaram no ensino comum, em diferentes contextos do Brasil e da Espanha, chegando ao ensino superior. Tais histórias podem mostrar que, mesmo na presença de condições orgânicas desfavoráveis, as pessoas se desenvolvem a partir das interações que estabelecem em seus grupos e das condições materiais de vida. A utilização de métodos narrativos em pesquisas sobre a deficiência mental possibilita o reconhecimento dos sujeitos da pesquisa como atores e autores de sua história. No caso desta pesquisa, foram realizadas repetidas entrevistas com os sujeitos-alvo, além de buscas de informações complementares, com professores e familiares, respeitando as especificidades de cada caso.Vivendo em diferentes contextos e de modos muito peculiares, é possível identificar nas três histórias o desafio aos prognósticos de deficiência mental e de baixa escolaridade, mostrando processos de compensação social que possibilitaram a superação de limites, ainda hoje vistos como intransponíveis. Buscou-se compreender os movimentos constitutivos das trajetórias desses sujeitos por meio da análise de eixos de sentido que envolveram: a ruptura com os prognósticos negativos e a construção de outras possibilidades de desenvolvimento, a escolarização na escola comum, a imagem que cada sujeito mostra de si e as vivências no mundo do trabalho. O olhar atento a essas e a outras histórias de ruptura pode nos ajudar a reafirmar que a constituição do ser humano em “humano”, ainda que em condições de desvantagem, se dá na relação com os demais.
This piece of research argues that mental deficiency is a condition that arises from social relations established with individuals who present unique characteristics in relation to the major part of population, and not as incapability. Based on a historical-cultural approach, this standpoint goes against traditional concepts of mental deficiency, especially that one informed by Vigotski. Notwithstanding any structural or functional organic alteration in the nervous system, a subject develops himself/herself through social relations – not as a mental handicap. As regards the methods, the story lives’ reports have been used of three adults with Down syndrome, who claimed to be mental deficiency-free. The three of them have been educated in regular schools, in Brazil and Spain, up to undergraduate level. These reports may portray that people develop themselves from interactions established in their groups and according to material resources available, despite their disfavorable organic conditions. Using narrative methods in research on mental deficiency enables one to acknowledge research subjects as actors and authors of their own story. In order to obtain data, target subjects have been interviewed, and mentors and relatives have also supplied additional information, always with respect to the specificities of each case. It was possible to identity challenge apropos the prognostics of mental deficiency and low education level in the three stories in the three different contexts and their very peculiar conditions. Social compensation processes seem to have enabled surpassing limits, which are taken as unsurpassable still in the present. Additionally, this research sought to comprehend constitutive elements of the subjects’ trajectory aforementioned. Directional axes’ analyses involved: breaking down negative prognostics, shaping up varied development possibilities, being educated at regular schools, the self-image each one presented, relations established in their workplace. Looking close at these and other breakthrough stories may help us reassure that one constitutes him/herself a human being relating to others, albeit disfavorable conditions.
Este trabajo presenta un estudio cuyo objetivo central es discutir la deficiencia mental como condición que se desarrolla a partir de las relaciones sociales establecidas con individuos que presentan características singulares en relación a la mayoría de la población y no como una incapacidad propia. Esta visión es contraria a las concepciones tradicionales de deficiencia mental y se apoya en el abordaje histórico/cultural, especialmente en las contribuciones de Vigotski. La idea básica es que, aún frente a cualquier alteración orgánica, aunque ésta sea a nivel estructural o funcional del sistema nervioso, será por y en las relaciones sociales que el individuo se desarrollará, o no, como deficiente mental. Como estrategia metodológica, se utilizaron relatos de historias de vida de tres adultos con síndrome de Down que se constituyeron como individuos sin deficiencia mental. Los tres estudiaron en escuelas comunes, en diferentes contextos de Brasil y de España, llegando a la enseñanza superior. Estas historias pueden mostrar que, aún en presencia de condiciones orgánicas adversas, las personas se desarrollan a partir de las interacciones que establecen en sus grupos y de las condiciones materiales de vida. El uso de métodos narrativos en estudios sobre la deficiencia mental facilita el reconocimiento de los individuos del estudio como actores y autores de su historia. En el caso de este estudio, se realizaron repetidas entrevistas con los individuos específicos, además de buscar informaciones complementarias, con profesores y familiares, respetando las especificaciones de cada caso. Viviendo en diferentes contextos y de formas muy peculiares, se puede identificar en las tres historias el desafío a los pronósticos de deficiencia mental y de baja escolaridad, mostrando procesos de compensación social que permitieron la superación de límites, aún hoy vistos como infranqueables. Se ha buscado comprender los movimientos constitutivos de las trayectorias de esos individuos por medio del análisis de ejes de sentido que involucraron: la ruptura con los pronósticos negativos y la construcción de otras posibilidades de desarrollo, el estudio en la escuela común, la imagen que cada individuo muestra de sí mismo y las vivencias en el mundo del trabajo. La mirada atenta a estas y a otras historias de ruptura nos puede ayudar a reafirmar que la constitución del ser humano en “humano”, aún en condiciones de desventaja, se da en la relación con los demás.

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Benamar, Mohamed Amine. "Développement d’une approche numérique et expérimentale par la mesure VLD pour la propagation acoustique mutimodale en conduit avec écoulement." Thesis, Compiègne, 2021. http://www.theses.fr/2021COMP2624.

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La Vélocimétrie Laser à effet Doppler (VLD) est un moyen de mesure non intrusif de la vitesse particulaire classiquement utilisé en mécanique des fluides. La vitesse acoustique est une grandeur très importante en acoustique car elle permet de caractériser les champs de propagation acoustique indispensable pour la compréhension de certains phénomènes de propagation en proche paroi ou pour des géométries complexes. Le banc DUCAT installé au laboratoire de l’équipe acoustique et vibration de l’Université de Technologie de Compiègne avait pour but de caractériser les performances acoustiques de différents systèmes d’absorption acoustique tel que les SDOF ou les poreux métalliques pour des utilisations aéronautiques à travers la mesure amont/aval de la vitesse et la pression acoustiques à travers deux sondes automatisées contenants un capteur à fil chaud ainsi qu’un microphone avec ogive. L’objectif de cette thèse est de permettre la mesure de la vitesse acoustique en propagation multimodale et en présence d’écoulement en utilisant la VLD. Le signal mesuré par la VLD est échantillonné aléatoirement et présente un bruit de fond assez important dû à la présence de l’écoulement dans le conduit. La nature complexe du signal mesuré demande des méthodes de traitement de signal particulières pour pouvoir en extraire la vitesse acoustique qui nous importe. La première partie de cette thèse, présente un benchmark des différentes méthodes présentes dans la littérature ainsi que leur validité pour les conditions expérimentales actuelles du banc DUCAT. Une simulation du signal VLD mesuré est développé en guise de référence de validation des méthodes qu’elles soient spectrales ou temporelles. La méthode des moindres carrés pondérés est finalement sélectionnée et adaptée suite à cette étude pour l’estimation des différents paramètres acoustiques à partir du signal brut. La deuxième partie concerne la présentation des outils numériques utilisés ou développés pour la simulation de la propagation acoustique dans les conduits infinis. L’outil numérique est un code éléments finis aéroacoustique basé sur les équations de Galbrun couplées à une couche absorbante virtuelle dite PML (Perfect Matched Layer). En raison de la présence de la PML, la résolution numérique du problème inverse devient compliquée et un code de résolution des problèmes aux valeurs propres non linéaires basé sur la méthode du Contour Intégral a dû être développé. La troisième partie de ce travail présente les différents composants du banc expérimental. Le banc permet la propagation acoustique multimodale (jusqu’à 5000 Hz) en présence d’un écoulement en aspiration/expiration pouvant atteindre une vitesse de Mach 0.25. La quatrième partie présente une comparaison numérique et expérimentale des outils présentés et développés durant la thèse. Une première comparaison pour une propagation multimodale dans un conduit droit permet de conclure sur l’efficacité du système de mesure et de traitement de signal avec une erreur relative inférieure à 1 dB. Une seconde comparaison a été réalisée pour l’étude des modes piégés acoustiques dans le cas d’un conduit cylindrique avec changement brusque de section
Laser Doppler Velocimetry (LDV) is a non-intrusive measurement of particle velocity classically used in fluid mechanics. The acoustic velocity is a very important quantity in acoustics for the characterization of acoustic propagation fields, which is essential for the understanding of certain propagation phenomena in near walls or for complex geometries. The DUCAT bench installed in the laboratory of the Acoustics and Vibration team of the University of Technology of Compiègne aimed at characterizing the acoustic performances of various acoustic absorption systems such as SDOF or metallic porous materials for aeronautical uses through the measurement of the acoustic velocity and pressure through two automated probes containing a hot wire sensor as well as a microphone with ogive. The objective of this thesis is to allow the measurement of acoustic velocity in multimodal propagation and in the presence of flow using the VLD. The signal measured by the VLD is randomly sampled and has a fairly large background noise due to the presence of flow in the duct. The complex nature of the measured signal requires special signal processing methods to extract the acoustic velocity that is important to us. The first part of this thesis presents a benchmark of the different methods available in the literature and their validity for the current experimental conditions of the DUCAT bench. A simulation of the measured VLD signal is developed as a reference to validate the methods, whether they are spectral or temporal. The weighted least squares method is finally selected and adapted following this study for the estimation of the various acoustic parameters from the raw signal. The second part concerns the presentation of the numerical tools used or developed for the simulation of the acoustic propagation in infinite ducts. The main numerical tool is an aeroacoustic finite element code developed in the lab based on Galbrun’s equations coupled to a virtual absorbing layer called PML (Perfect Matched Layer). Due to the presence of the PML, the numerical solution of the inverse problem becomes complicated, which led us to develop a code for solving nonlinear eigenvalue problems based on the Integral Contour method. The third part of this work presents the different components of the modified version of the bench as well as the characteristics of these different components. The bench allows the experimentation of multimodal acoustic propagation (up to 5000 Hz) in the presence of a suction/expiration flow that can reach a speed of Mach 0.25. The fourth and last part, presents a protocol of experimental numerical validation of all the tools presented and developed. The test/calculation comparisons are presented for a multimodal propagation in a straight duct at first. The results allow to conclude on the efficiency of the measurement and signal processing system with a relative error lower than 1 dB. The same protocol is then used for the experimental study of the acoustic trapped modes in the case of a cylindrical duct with an abrupt change of section

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Huang, Yun. "Nonlinear optimal control: an enhanced quasi-LPV approach." Thesis, 1999. https://thesis.library.caltech.edu/1917/1/Huang_y_1999.pdf.

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Realistic models of physical systems are often nonlinear. Our objective is to synthesize controllers for nonlinear systems that not only provide stability, but also deliver good closed-loop performance. The frozen Riccati equation approach is thoroughly examined. Although it suffers fundamental deficiencies due to its pointwise nature, it is proven that optimality is always possible under a certain assumption on the optimal value of the performance index. This is a consequence of the non-uniqueness of the pointwise linear model of the nonlinear dynamics. However, one cannot assess a priori the guaranteed global performance for a particular model choice. An alternative to the pointwise design is to treat nonlinear plants as linear parameter varying systems with the underlying parameters being functions of the state variables. By exploiting the variation rate bounds of the parameters, a controller that smoothly schedules on the parameters can be synthesized by solving a convex optimization problem. Depending upon the choice of the variation rate bounds, the resulting controller can range from replicating the pointwise design result, which comes with no guarantee on performance, to providing quadratic stability, in which case it can withstand arbitrarily fast parameter variation. Under the above quasi-LPV framework, we present a new scheme that incorporates the freedom of choosing the state-dependent linear representation into the control design process. It is shown that the L2-gain analysis can be reformulated as an infinite dimensional convex optimization problem, and an approximate solution can be obtained by solving a collection of linear matrix inequalities. The synthesis problem is cast as a minimization over an infinite dimensional bilinear matrix inequality constraint. An iterative algorithm, similar to the "D - K iteration" for µ synthesis, is proposed to compute the best achievable performance. It is demonstrated through several examples that this approach can effectively reduce conservatism of the overall design.

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Qin, Wubi. "Feedback performance control for self-managing computer systems an LPV control theoretic approach /." 2007. http://www.etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-1958/index.html.

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Zhang, Hai. "Robust LPV control of a magnetic bearing suspension system with a convex optimization approach /." 2003. http://wwwlib.umi.com/dissertations/fullcit/3083092.

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McCloy, Ryan. "A set-theoretic approach to sensor fault tolerant control of constrained linear parameter varying systems." Thesis, 2018. http://hdl.handle.net/1959.13/1398743.

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Research Doctorate - Doctor of Philosophy (PhD)
One of the traditional motivators for the use of constrained optimisation in control systems has been its ability to handle safety constraints and equipment limitations over conventional control technologies, whereby operation close to such constraints is often most profitable or efficient. Driven by this, combined with advances in computing power and the development of analytical tools, academic interests have paved the way for expanding practical applications. In competitive markets where efficiency and performance are key, optimisation based control techniques are becoming increasingly popular. Although linear analysis and control tools have been widely studied, nonlinear solutions are still largely under development. The linear parameter varying framework is attractive as it allows for the use of powerful linear design tools to a wide range of complex nonlinear systems. Linear parameter varying models also have a close relationship with gain-scheduling control, which is a well-defined control strategy for a large class of nonlinear systems. The development of techniques to assess linear parameter varying system stability has also motivated the use of this modelling paradigm. Many of these techniques allow for the use of efficient computation methods, such as linear matrix inequality based routines. Whilst performance requirements are essential, another key feature to modern control system design is the robustness and stability of the design. With a heavy reliability upon the plant model in optimised control, it is significantly important to be able to efficiently handle a range of possible system faults/failures. With this in mind, exploration of new methodologies to ensure closed-loop stability, constraint satisfaction and robustness of design to system faults is a lively, interesting and useful topic for modern control system designers. The problems of stability, robustness, and fault tolerance, especially in model predictive control, are very much open problems for nonlinear systems, with no well-defined solution. As such, there is a great realm of opportunity for research and contribution to these areas. This thesis is then concerned with the development of sensor fault tolerant control strategies for mulitsensor constrained linear parameter systems. Fault tolerance is achieved via an invariant set-theoretic approach, in which, appropriately selected residual variables converge to sets based on the healthy or faulty behaviour of corresponding sensors. The established methodologies incorporate this set-based fault detection and isolation strategy combined with an estimate-based controller reconfiguration. Full mathematical description and proof for the robust stability of systems with convex polytopic uncertainty through the construction of attractive invariant sets is obtained. This result is an adaptation from switched systems and is particularly useful for systems modelled using the linear parameter varying framework. Initially, faulty sensors are detected and discarded from the control law utilising the developed analytical tools. The problem and comparison of several solutions of estimating convergence times to invariant sets is investigated as an extension of the set-theoretic tools. Using convergence time estimates, the overall approach is then naturally progressed to permit sensor reintegration, by detecting and tracking the transitions and set-membership of residual signals associated with faulty and recovered sensor behavior. Continuing with the set-theoretic nature of the overall approach, a tube-based model predictive controller is then integrated into the design methodology to provide constraint satisfaction. Driven by a tube-based model predictive control generated reference, conditions are formulated which guarantee satisfaction of hard constraints by defining tubes with cross sections that will contain the predicted state trajectory. Under this approach, bounded disturbances and model uncertainty can also be accounted for by forcing the nominal system to adhere to tighter constraints. Hence, this thesis provides certificates for assessing the robust stability of constrained linear parameter varying systems, in the presence of disturbances, model uncertainty, sensor faults and sensor recovery. Capabilities for instantaneous fault detection and guaranteed closed-loop stability in the presence of hard constraints is provided, whilst permitting the reintegration of recovered sensors with guaranteed convergence times. Simulated and experimental verification of the developed strategies is provided to demonstrate the performance characteristics and preservation of closed-loop stability through the implementation and testing of targeted applications. Although linear analysis and control tools have been widely studied, nonlinear solutions are still largely under development. The linear parameter varying framework is attractive as it allows for the use of powerful linear design tools to a wide range of complex nonlinear systems. Linear parameter varying models also have a close relationship with gain-scheduling control, which is a well-defined control strategy for a large class of nonlinear systems. The development of techniques to assess linear parameter varying system stability has also motivated the use of this modelling paradigm. Many of these techniques allow for the use of efficient computation methods, such as linear matrix inequality based routines. Whilst performance requirements are essential, another key feature to modern control system design is the robustness and stability of the design. With a heavy reliability upon the plant model in optimised control, it is significantly important to be able to efficiently handle a range of possible system faults/failures. With this in mind, exploration of new methodologies to ensure closed-loop stability, constraint satisfaction and robustness of design to system faults is a lively, interesting and useful topic for modern control system designers. The problems of stability, robustness, and fault tolerance, especially in model predictive control, are very much open problems for nonlinear systems, with no well-defined solution. As such, there is a great realm of opportunity for research and contribution to these areas. This thesis is then concerned with the development of sensor fault tolerant control strategies for mulitsensor constrained linear parameter systems. Fault tolerance is achieved via an invariant set-theoretic approach, in which, appropriately selected residual variables converge to sets based on the healthy or faulty behaviour of corresponding sensors. The established methodologies incorporate this set-based fault detection and isolation strategy combined with an estimate-based controller reconfiguration. Full mathematical description and proof for the robust stability of systems with convex polytopic uncertainty through the construction of attractive invariant sets is obtained. This result is an adaptation from switched systems and is particularly useful for systems modelled using the linear parameter varying framework. Initially, faulty sensors are detected and discarded from the control law utilising the developed analytical tools. The problem and comparison of several solutions of estimating convergence times to invariant sets is investigated as an extension of the set-theoretic tools. Using convergence time estimates, the overall approach is then naturally progressed to permit sensor reintegration, by detecting and tracking the transitions and set-membership of residual signals associated with faulty and recovered sensor behavior. Continuing with the set-theoretic nature of the overall approach, a tube-based model predictive controller is then integrated into the design methodology to provide constraint satisfaction. Driven by a tube-based model predictive control generated reference, conditions are formulated which guarantee satisfaction of hard constraints by defining tubes with cross sections that will contain the predicted state trajectory. Under this approach, bounded disturbances and model uncertainty can also be accounted for by forcing the nominal system to adhere to tighter constraints. Hence, this thesis provides certificates for assessing the robust stability of constrained linear parameter varying systems, in the presence of disturbances, model uncertainty, sensor faults and sensor recovery. Capabilities for instantaneous fault detection and guaranteed closed-loop stability in the presence of hard constraints is provided, whilst permitting the reintegration of recovered sensors with guaranteed convergence times. Simulated and experimental verification of the developed strategies is provided to demonstrate the performance characteristics and preservation of closed-loop stability through the implementation and testing of targeted applications.

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Hamdi, Habib. "Approche Multi-Modèle pour l'Observation d'état et le Diagnostic des Systèmes Singuliers Non Linéaires." Phd thesis, 2012. http://tel.archives-ouvertes.fr/tel-00757821.

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Le premier chapitre présente un état de l'art sur le sujet traité. Il s'intéresse à introduire la classe des systèmes singuliers. Ces systèmes constituent un puissant outil de modélisation dans la mesure où ils peuvent décrire des processus régis à la fois par des équations dynamiques et des équations statiques. Ce formalisme est ainsi particulièrement adapté à l'étude des systèmes interconnectés, soumis à des contraintes physiques statiques et présentant des comportements impulsifs. Plusieurs résultats fondamentaux relatifs à la localisation et à l'analyse des systèmes singuliers linéaires, à paramètres variants ou non linéaires sont ainsi rappelés. Le deuxième chapitre est consacré au problème d'approximation des systèmes singuliers à paramètres variants et non linéaires par une représentation multi-modèle. Cette approche permet de présenter un processus dynamique non linéaire comme une combinaison d'un ensemble de modèles linéaires ou a nes valables dans des zones de fonctionnement. Les différentes structures les plus utilisées (modèles locaux couplés et découplés) sont décrites. L'analyse de la stabilité des multi-modèles a été considérée. Une méthode de synthèse de deux types d'observateurs pour les systèmes singuliers multi-modèles et LPV polytopique est aussi introduite. Le problème de diagnostic des systèmes singuliers non linéaires par approche multimod èles et des systèmes singuliers à paramètres variants polytopiques est abordé dans le troisième chapitre. Trois méthodes à base d'observateurs sont alors proposées. La première approche repose sur l'utilisation d'un multi-observateur à entrées inconnues assurant un découplage partiel de l'estimation des défauts. La deuxième méthode est inspirée du probl ème standard de commande H∞. Elle est basée sur la minimisation de l'influence des entrées inconnues et la maximisation de l'in uence des défauts sur les résidus, ce qui revient à l'étude d'un problème multiobjectifs. La troisième méthode est basée sur l'utilisation d'un multi-observateur Proportionnel Intégral (PI). Cette approche est utilisée avec les systèmes singuliers à paramètres variants. Elle permet moyennant un banc de générateurs de résidus, de fournir directement une estimation des défauts et par suite leur détection et localisation.

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Pathak, Gopal Prasad [Verfasser]. "A metagenomic approach towards novel LOV domain containing blue-light photoreceptors / vorgelegt von Gopal Prasad Pathak." 2010. http://d-nb.info/1006921540/34.

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Gameiro, Mafalda Martins de Campos. "A person-centred approach to the job demands-control model : testing strain and learning hypotheses through lpa." Master's thesis, 2018. http://hdl.handle.net/10451/36771.

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Tese de mestrado, Psicologia (Secção de Psicologia dos Recursos Humanos, do Trabalho e das Organizações), Universidade de Lisboa, Faculdade de Psicologia, 2018
We used a cross-sectional design and a person-centred approach in order to test the strain and learning hypothesis of Karasek’s Job Demands-Control Model among a sample of Portuguese nurses, bankers, retail traders and contact centre employees (n = 5641). Through Latent Profile Analysis (LPA), we first identified latent profiles of demands and control and then examined how these groups differed in well-being (engagement, exhaustion and cynicism levels) and motivation- related outcomes (engagement), through an ANCOVA. LPA revealed five profiles: “High-strain”, “Moderate-strain”, “Moderate Active”, “Moderate” and “Active”. The strain hypothesis was supported in both direct effects and interactive effects (buffer hypothesis), suggesting that the difficulty in finding consistent support for the buffer hypothesis might be related to the use of variable-centred approaches. Moreover, this shows that, in organizational practice, if control is provided there is no necessary need in reducing demands at work, as control will buffer demands’ harmful effects on well-being. Learning hypothesis could not be tested due to the fact that a Passive profile was not found in this sample. However the comparisons between the “Active” and the “Moderate” profiles suggests that motivation is higher in the presence of both high job demands and control. This leads us to believe that when people are presented with considerable demands and have control over they jobs, they will be more motivated to grow professionally and consequently obtain better outcomes.
Utilizou-se um desenho experimental transversal e uma abordagem centrada na pessoa por forma a testar a hipóteses de strain e a hipótese de aprendizagem propostas no Modelo de Exigências e Controlo (Job Demands-Control Model) de Karasek. Para tal, usou-se uma metodologia de análise de perfis latentes numa amostra de enfermeiros, bancários, comerciais de retalho e empregados de contact centre portugueses (n = 5641), para identificar os perfis latentes de exigências e controlo. Dessa análise surgiram cinco perfis: “High-strain”, “Moderate-strain”, “Moderate Active”, “Moderate” e “Active”. A seguir, através de uma ANCOVA examinou-se como é que estes grupos diferiam em termos de bem-estar (i.e. engagement, exaustão e cinismo) e motivação (i.e. engagement). A hipótese de strain foi corroborada, tanto em termos de efeitos diretos como interativos (hipótese de buffer), sugerindo que a anterior dificuldade em encontrar resultados neste sentido, poderá dever-se ao uso de abordagens centradas nas variáveis. Mais ainda, em termos práticos, estes resultados reforçam que quando existe controlo suficiente no trabalho não é impreterível que se reduzam as exigências uma vez que o controlo sentido irá atenuar os efeitos negativos das mesmas no bem-estar do indivíduo. A hipótese de aprendizagem não pode ser testada uma vez que não surgiu um perfil passivo como se tinha proposto inicialmente. Contudo, as comparações entre os perfis “Active” e “Moderate” sugerem que há maiores níveis de motivação na presença conjunta de altas exigências e alto controlo. Isto leva-nos a crer que trabalhadores com elevadas exigências mas também com alto níveis de controlo sobre o seu trabalho, estarão mais motivados a crescer profissionalmente e, a obter melhores resultados.

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Gousseva, Anastasia. "Investigating the Expansion of Angiosperms during the Cretaceous Period using a Modeling Approach." Thesis, 2010. http://hdl.handle.net/1807/25601.

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The use of Dynamic Global Vegetation Models (DGVMs) in paleo-vegetation studies is a practical new approach in paleo-ecology as it allows for process-based investigations within a flexible framework. The goal of this study is to evaluate the applicability of Lund Potsdam Jena (LPJ) – DGVM in a paleo-study of Cretaceous angiosperm spread, while testing several pre-existing theories regarding the spread through model experimentation. I assessed the independent and interactive role of climate variables (temperature, precipitation, atmospheric CO2 concentration, and seasonality), latitudinal light regime, soil structure, and plant characteristics (tree versus grass, and deciduousness) in influencing angiosperm expansion by simulating the response of Cretaceous land cover to changes in each factor. I found that temperature and light were the most influential variables in determining angiosperm success, while plant structure and deciduousness may carry implications for early angiosperm establishment and community competition dynamics. LPJ showed great potential for refinement and effective future use in paleo-applications.

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Lin, Ming-Ching, and 林明靜. "Study on anti-lipopolysaccharide factor modulation of LPS-mediated inflammatory response in murine macrophage RAW264.7 cell by microarray approach." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/78458898982082378176.

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碩士
國立宜蘭大學
生物技術研究所碩士班
97
The shrimp anti-lipopolysaccharide factor peptide (anti-LPS), SALF, has been demonstrated to protect animals against sepsis. Gram-negative bacterial sepsis may be due to the activation of host immune responses by LPS. LPS may go through the MAPK or NFκB pathway to increase the level of the proinflammatory cytokines, such as tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, IL-12, and IL-10, which may damage cells and lead to organ injury. The most important proinflammatory cytokine was TNF-α. RAW264.7 cell was treated with LPS (10 or 100 ng/ml) with different concentrations of SALF (0~100 μg/ml) for 4h, and the cell culture supernatants were screened for TNF-α by ELISA. The observation showed that SALF (20 μg/ml) was able to modulate the inflammatory responses by inhibiting the release of the TNF-α in LPS (100μg/ml)-stimulated mouse macrophage cells (RAW264.7). Treatment of SALF for 2h followed by LPS for 24h in RAW264.7 cells inhibited the TNF-α production around 79.1%. The microarray results showed that some genes had been modulated by two-fold changes. We selected the genes encoding immune-related proteins such as CD36, SCAR, ITGAX, CLU, ACTB, MYC, ANP32A, KLF2, CDC25L, SLPI, KS1, NOD1 and NFκB, which changed two-fold up or down for further analysis. Furthermore, we checked the expression of selected genes by real-time PCR in SALF and LPS treated RAW264.7 cells with the presence of specific inhibitors or activators to confirm the NFκB mediated mechanism. Finally, we found that SALF not only inhibited TNF-α, but also inhibited the cytokine of IL-1β and IL-6.

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Teixeira, Santos Ana Carolina. "Working memory and neuroplasticity in older people: a behavioural and neurofunctional approach." Doctoral thesis, 2020. http://hdl.handle.net/1822/76490.

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Tese de doutoramento em Psicologia Básica
Working memory training (WMT) has been used to promote neuroplasticity in older people and tDCS has been proposed to boost WMT effects. Nevertheless, there is not robust evidence of WMT effectiveness and the few studies assessing the combination of tDCS with WMT used cognitive tasks as endpoints. However, the use of different markers, as the event-related potentials (ERPs), can be useful to better understand the combined or individual effects of these interventions. Thus, the studies presented in this dissertation aimed to assess WMT effects, as well as, the add-on effects of tDCS. Given the need to use different endpoints to measures WMT-induced neuroplasticity, an additional aim was to assess if the ERPs can be used as indexes of fluid intelligence (Gf), a commonly assessed constructed to infer generalization of WMT. In the first study, we presented a meta-analysis on the effects of WMT in healthy elderly. Small significant and long-lasting gains were observed in working memory (WM), but not in short-term memory (STM) and Gf tasks. Type of training tasks, the adopted outcome measures, the training duration, and the total number of training hours moderated WMT effects. In the second study, we performed a systematic review on the uses of tDCS to boost WM in healthy older adults. The studies suggest that tDCS may modulate WM in this population, improving the accuracy and shortening the reaction time. In the third study, we performed a randomized double-blind controlled experiment to evaluate the effects of 5-day WMT coupled with tDCS in healthy older adults. Fifty-four participants were assigned to one of three groups: 1) WMT (dual n-back task)+active tDCS (atDCS); 2) WMT+sham tDCS (stDCS); or 3) sham task + sham tDCS. During the training, both groups that performed the dual n-back task (WMT+atDCS; WMT+stDCS) improved throughout sessions, with no significant differences between them. However, the “WMT+atDCS” was the only group that presented gains in Gf and verbal STM after training (i.e., next day after the intervention) and at follow-up (i.e., 15 days follow-up). Finally, in the fourth study, we explored whether ERP components (i.e., P2, P3b and the LPC - late positive complex) are associated with Gf in the elderly. Fifty-seven participants performed a continuous performance task and a visual oddball paradigm while EEG was recorded. They were divided into high-performance (HP) and low performance (LP) groups according to their performance in the Raven’s Advanced Progressive Matrices test (RAPM). HP group presented significant higher LPC amplitudes in the CPT and shorter P3b latencies in the oddball task when compared to the LP group.
O treino da memória de trabalho (WMT) tem sido usado para promover neuroplasticidade em idosos e a ETCC tem sido adotada para potencializar seus efeitos. No entanto, não há evidências robustas da eficácia do WMT e os poucos estudos que avaliaram a combinação da ETCC com o WMT usaram tarefas cognitivas como medidas. O uso de diferentes marcadores, como os potenciais evocados (ERPs), pode ser útil para entender melhor os efeitos dessas intervenções. Assim, os estudos desta dissertação objetivaram avaliar os efeitos do WMT, bem como, os efeitos adicionais da ETCC. Dada a necessidade de usar diferentes parâmetros para mensurar a neuroplasticidade induzida pelo WMT, um objetivo adicional foi avaliar se os ERPs procedem como índices de inteligência fluida (Gf), um construto comumente avaliado para inferir generalização do WMT. No primeiro estudo, apresentamos uma meta-análise sobre os efeitos do WMT em idosos. Foram observados pequenos e duradouros ganhos na memória de trabalho (WM), mas não na memória a curto prazo (STM) e Gf. O tipo de tarefas treinadas, as medidas adotadas e a duração/número total de horas de treino moderaram os efeitos. No segundo estudo, realizamos uma revisão sistemática sobre o uso de ETCC para melhorar a WM em idosos saudáveis. Os estudos sugerem que a ETCC pode modular a WM nessa população, aumentando a precisão e reduzindo o tempo de reação. No terceiro estudo, foi realizado um experimento aleatório duplo-cego para avaliar os efeitos do WMT associados à ETCC. Cinquenta e quatro idosos foram designados para um de três grupos: 1) WMT (tarefa dual n-back) + ETCC ativa (aETCC); 2) WMT + sham ETCC (sETCC); ou 3) tarefa placebo + sham ETCC. Durante o treino, os dois grupos que realizaram a tarefa dual n-back (WMT+aETCC; WMT+sETCC) melhoram ao longo das sessões, sem diferenças significativas entre eles. No entanto, o "WMT + aETCC" foi o único grupo que apresentou ganhos na Gf e STM após o treino e no seguimento de 15 dias. Por fim, no quarto estudo, exploramos se os componentes dos ERPs (P2, P3b e LPC – late positive complex) estão associados à Gf. Cinquenta e sete idosos realizaram uma tarefa de desempenho contínuo (CPT) e um oddbball visual enquanto o EEG era gravado. Participantes foram divididos em grupos de alto desempenho (HP) e baixo desempenho (LP) de acordo com seu desempenho na Matrizes Progressivas Avançadas de Raven (RAPM). O grupo HP apresentou amplitudes superiores no LPC evocado pela tarefa CPT e latências mais curtas na P3b evocada pela oddball quando comparado com o grupo LP.
Fundação BIAL
Fundação para a Ciência e a Tecnologia (FCT)

47

Mutale, Oswald Levy. "Climate change mitigation: an analysis of liquefied petroleum gas (LPG) as an alternative domestic energy source to charcoal in Zambia." Diss., 2019. http://hdl.handle.net/10500/25775.

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This study analyses the possibility of introducing liquefied petroleum gas (LPG) as an alternative domestic energy source to charcoal in Zambia to mitigate climate change. The study, conducted in Lusaka, used questionnaires, focus group discussions, interviews and literature study to collect data. The study revealed that the introduction of LPG is possible. However, some challenges need to be addressed in order to actualise the change. Lack of knowledge about LPG; non-availability of LPG in most parts of the country; perceived danger of LPG; high prices of LPG and accessories; changing people‟s mind-sets about charcoal; social inequity and lack of government initiative, were the main challenges identified. Social-Ecology and sustainable livelihoods were used as theoretical frameworks to ground the study and analyse the results. The study recommends that government takes the lead to make the change possible and that further research be done on sustainable livelihoods for charcoal producers and traders.
Development Studies
M. A. (Development Studies)

48

Amaro-Leal, Ângela. "Peripheral multiorgan dysfunction induced by sepsis : the role of NFκB pathway and its impact on brain and heart function." Doctoral thesis, 2018. http://hdl.handle.net/10451/48472.

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Sepsis and sepsis-associated multiorgan failure represent a systemic inflammatory state mediated by the innate immune system resulting in an excessive cellular response to severe infection, with high levels of morbidity and mortality. Furthermore, patients who survive sepsis, have long-term cognitive and functional impairment. Animal models are essential to clarify the pathophysiological mechanisms of sepsis. There is mounting evidence that inhibition of nuclear factor NFκB activation can reduce sepsis-associated organ dysfunction and injury. Herein, we deeply characterize an animal model of lipopolysaccharide (LPS)-induced acute inflammation, through an integral functional, behavioural, morphological and molecular evaluation as well as tested different possible therapeutic approaches to determine their efficacy on the modulation of systemic inflammation through the NF-kB pathway. Male and female Wistar rats (12-20 weeks) were injected with LPS (E. coli serotype O127:B8; tail IV) and divided into three groups: LPS 6 (6mg/kg), LPS 12 (12mg/kg) and SHAM (NaCl 0.9%). At 6 h and 24 h after LPS administration, an autonomic evaluation was performed in both conscious animals, with continuous radio-telemetry recording of blood pressure (BP) and heart rate (HR), and anesthetized animals with BP, ECG, HR, tracheal pressure, respiratory frequency (RF) and body temperature continuously monitored. Baro- and chemoreflexes were evaluated with phenylephrine and lobeline, respectively. Behavioural changes were also evaluated through the elevated-plus maze (anxiety), open-field (locomotor/exploratory activity) and Y-maze (short-term spatial working memory) tests. Immunohistochemistry and RT-PCR were executed to determine heart and brain inflammatory state. Serum biomarkers levels for organ disfunction were also measured. For the test of potential therapeutic drugs, animals were exposed with the two LPS doses and treated 15 minutes later with four different drugs: erythropoietin, dexamethasone, IKK 16 and adenosine. The functional, behavioural, and molecular analysis were performed. Overall, the characterization model results showed a rise in BP and HR and elevated RF, indicative of tachycardia and tachypnea. The higher RF was concomitant with a higher chemoreceptor reflex sensitivity. The autonomic data reveals an overexcitation of sympathetic tone with a sympatho-vagal imbalance, concomitant with baroreflex impairment and/or increases in BP, all these were strongly marked in the highest LPS dose. At both time-points, both LPS groups show an anxiety-like behaviour, associated with lower locomotor and exploratory capacity and short-term memory impairment. The molecular studies show reactive astrogliosis and microgliosis, due to inflammatory processes in the hippocampus, as well as, an upregulation of pro-inflammatory factors in the heart and brain. Serum analysis yielded higher levels of biomarkers for renal and liver dysfunction, and pancreatic and neuromuscular injury, mainly in the LPS 12 group. The functional, behavioral, and molecular response between female and male rats was not so different. Both sexes present markedly changes when exposed to higher doses of LPS. Indeed, male animals are more sensitive to endotoxin that females, that can fight inflammation more easily. Of the four therapeutic proposals studied, erythropoietin and dexamethasone were the best to modulate the NF-ΚB pathway in order to reduce the dysfunction of multiple organs as well as attenuate the behavioural changes caused by the exposure to endotoxin. Both IKK 16 and adenosine treatments attenuate the organ dysfunction by reducing the serum renal, hepatic, pancreatic and neuromuscular levels, however these two drugs did not improve the cardiac and behavioral modifications. Further studies are needed in order to better understand the role of these drugs in the early stages of sepsis. Summarizing, higher doses of LPS induces strong alterations in both cardiac and neurological systems, as well as, multiple organ dysfunction, that can be attenuated by the administration of specific NF-κB modulators, such as, erythropoietin and dexamethasone. These findings served to better understand the pathophysiological processes involved in these animal model of acute inflammation as well as showed therapeutic evidence that through NF-κB signalling pathway modulation it is possible to attenuate or even reverse the acute stages before this condition evolves to more aggressive stages, namely septic shock and ultimately dead.

49

Srivastava, Shweta. "Stabilization Schemes for Convection Dominated Scalar Problems with Different Time Discretizations in Time dependent Domains." Thesis, 2017. http://etd.iisc.ac.in/handle/2005/3574.

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Problems governed by partial differential equations (PDEs) in deformable domains, t Rd; d = 2; 3; are of fundamental importance in science and engineering. They are of particular relevance in the design of many engineering systems e.g., aircrafts and bridges as well as to the analysis of several biological phenomena e.g., blood ow in arteries. However, developing numerical scheme for such problems is still very challenging even when the deformation of the boundary of domain is prescribed a priori. Possibility of excessive mesh distortion is one of the major challenge when solving such problems with numerical methods using boundary tted meshes. The arbitrary Lagrangian- Eulerian (ALE) approach is a way to overcome this difficulty. Numerical simulations of convection-dominated problems have for long been the subject to many researchers. Galerkin formulations, which yield the best approximations for differential equations with high diffusivity, tend to induce spurious oscillations in the numerical solution of convection dominated equations. Though such spurious oscillations can be avoided by adaptive meshing, which is computationally very expensive on ne grids. Alternatively, stabilization methods can be used to suppress the spurious oscillations. In this work, the considered equation is designed within the framework of ALE formulation. In the first part, Streamline Upwind Petrov-Galerkin (SUPG) finite element method with conservative ALE formulation is proposed. Further, the first order backward Euler and the second order Crank-Nicolson methods are used for the temporal discretization. It is shown that the stability of the semi-discrete (continuous in time) ALE-SUPG equation is independent of the mesh velocity, whereas the stability of the fully discrete problem is unconditionally stable for implicit Euler method and is only conditionally stable for Crank-Nicolson time discretization. Numerical results are presented to support the stability estimates and to show the influence of the SUPG stabilization parameter in a time-dependent domain. In the second part of this work, SUPG stabilization method with non-conservative ALE formulation is proposed. The implicit Euler, Crank-Nicolson and backward difference methods are used for the temporal discretization. At the discrete level in time, the ALE map influences the stability of the corresponding discrete scheme with different time discretizations, and it leads to schemes where conservative and non-conservative formulations are no longer equivalent. The stability of the fully discrete scheme, irrespective of the temporal discretization, is only conditionally stable. It is observed from numerical results that the Crank-Nicolson scheme induces high oscillations in the numerical solution compare to the implicit Euler and the backward difference time discretiza-tions. Moreover, the backward difference scheme is more sensitive to the stabilization parameter k than the other time discretizations. Further, the difference between the solutions obtained with the conservative and non-conservative ALE forms is significant when the deformation of domain is large, whereas it is negligible in domains with small deformation. Finally, the local projection stabilization (LPS) and the higher order dG time stepping scheme are studied for convection dominated problems. The analysis is based on the quadrature formula for approximating the integrals in time. We considered the exact integration in time, which is impractical to implement and the Radau quadrature in time, which can be used in practice. The stability and error estimates are shown for the mathematical basis of considered numerical scheme with both time integration methods. The numerical analysis reveals that the proposed stabilized scheme with exact integration in time is unconditionally stable, whereas Radau quadrature in time is conditionally stable with time-step restriction depending on the ALE map. The theoretical estimates are illustrated with appropriate numerical examples with distinct features. The second order dG(1) time discretization is unconditionally stable while Crank-Nicolson gives the conditional stable estimates only. The convergence order for dG(1) is two which supports the error estimate.

50

Srivastava, Shweta. "Stabilization Schemes for Convection Dominated Scalar Problems with Different Time Discretizations in Time dependent Domains." Thesis, 2017. http://etd.iisc.ernet.in/2005/3574.

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Abstract:

Problems governed by partial differential equations (PDEs) in deformable domains, t Rd; d = 2; 3; are of fundamental importance in science and engineering. They are of particular relevance in the design of many engineering systems e.g., aircrafts and bridges as well as to the analysis of several biological phenomena e.g., blood ow in arteries. However, developing numerical scheme for such problems is still very challenging even when the deformation of the boundary of domain is prescribed a priori. Possibility of excessive mesh distortion is one of the major challenge when solving such problems with numerical methods using boundary tted meshes. The arbitrary Lagrangian- Eulerian (ALE) approach is a way to overcome this difficulty. Numerical simulations of convection-dominated problems have for long been the subject to many researchers. Galerkin formulations, which yield the best approximations for differential equations with high diffusivity, tend to induce spurious oscillations in the numerical solution of convection dominated equations. Though such spurious oscillations can be avoided by adaptive meshing, which is computationally very expensive on ne grids. Alternatively, stabilization methods can be used to suppress the spurious oscillations. In this work, the considered equation is designed within the framework of ALE formulation. In the first part, Streamline Upwind Petrov-Galerkin (SUPG) finite element method with conservative ALE formulation is proposed. Further, the first order backward Euler and the second order Crank-Nicolson methods are used for the temporal discretization. It is shown that the stability of the semi-discrete (continuous in time) ALE-SUPG equation is independent of the mesh velocity, whereas the stability of the fully discrete problem is unconditionally stable for implicit Euler method and is only conditionally stable for Crank-Nicolson time discretization. Numerical results are presented to support the stability estimates and to show the influence of the SUPG stabilization parameter in a time-dependent domain. In the second part of this work, SUPG stabilization method with non-conservative ALE formulation is proposed. The implicit Euler, Crank-Nicolson and backward difference methods are used for the temporal discretization. At the discrete level in time, the ALE map influences the stability of the corresponding discrete scheme with different time discretizations, and it leads to schemes where conservative and non-conservative formulations are no longer equivalent. The stability of the fully discrete scheme, irrespective of the temporal discretization, is only conditionally stable. It is observed from numerical results that the Crank-Nicolson scheme induces high oscillations in the numerical solution compare to the implicit Euler and the backward difference time discretiza-tions. Moreover, the backward difference scheme is more sensitive to the stabilization parameter k than the other time discretizations. Further, the difference between the solutions obtained with the conservative and non-conservative ALE forms is significant when the deformation of domain is large, whereas it is negligible in domains with small deformation. Finally, the local projection stabilization (LPS) and the higher order dG time stepping scheme are studied for convection dominated problems. The analysis is based on the quadrature formula for approximating the integrals in time. We considered the exact integration in time, which is impractical to implement and the Radau quadrature in time, which can be used in practice. The stability and error estimates are shown for the mathematical basis of considered numerical scheme with both time integration methods. The numerical analysis reveals that the proposed stabilized scheme with exact integration in time is unconditionally stable, whereas Radau quadrature in time is conditionally stable with time-step restriction depending on the ALE map. The theoretical estimates are illustrated with appropriate numerical examples with distinct features. The second order dG(1) time discretization is unconditionally stable while Crank-Nicolson gives the conditional stable estimates only. The convergence order for dG(1) is two which supports the error estimate.

Dissertations / Theses on the topic 'LPV approach'

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