Ce mémoire analyse et valide des applications possibles de méthodes de réduction de modèle pour la simulation directe, et la résolution de problèmes inverses d'estimation de paramètres sur des modèles complexes. Il se concentre sur la réduction par proper orthogonal decomposition (POD), et ses extensions. On démontre d'abord de nouvelles estimations a priori pour l'erreur de réduction sur des problèmes abstraits types (paraboliques et hyperboliques, linéaires ou avec non-linéarités lipschitziennes), validées dans de nombreux cas non linéaires. On évite notamment le problème de contrôle des termes d'ordre élevé par l'exploitation d'une suite spécifique de normes de projecteurs. Puis, pour couvrir les systèmes dépendant de paramètres, et par des résultats d'interpolation, on adapte la méthode précédente en réduction par multi-POD. On étend aussi, au prix d'un terme additif, les estimations a priori précédentes pour l'erreur maximum de réduction sur une plage paramétrique donnée. On illustre la puissance de la méthode sur le système électrophysiologique de FitzHugh-Nagumo, fortement sensible aux variations paramétriques. On valide enfin numériquement les versions réduites, toujours avec la réduction par multi-POD, de problèmes d'estimation de paramètres : de type variationnel avec le système de FitzHugh-Nagumo, et de type séquentiel (filtrage " kalmanien ") avec un modèle mécanique de coeur (multiéchelles, 3D, grandes déformations). En particulier, la méthode présente une efficacité et une robustesse similaires à celles obtenues pour les problèmes directs.

Thesis (M.A. (Human Movement Sciences))--North-West University, Potchefstroom Campus, 2008.

Thesis (M.A. (Human Movement Sciences))--North-West University, Potchefstroom Campus, 2008.

Orientador: Percival Bueno de Araujo / Banca: Anna Diva Plasencia Lotufo / Banca: George Lauro Ribeiro de Brito / Resumo: Este trabalho apresenta estudos referentes à estabilidade a pequenas perturbações do SEP, considerando a atuação de FACTS para o amortecimento das oscilações eletromecânicas de baixa frequência. São abordados os dispositivos FACTS TCSC (Thyristor Controlled Series Capacitor) e o SSSC (Static Synchronous Series Compensator). É realizada a representação e modelagem dos dispositivos FACTS no SEP inserindo no Modelo Sensibilidade de Potência. Para melhorar o desempenho do SEP no que se refere à estabilidade a pequenas perturbações, controladores suplementares são propostos para aumentar o desempenho dos dispositivos TCSC e SSSC, introduzindo o amortecimento necessário ao SEP. Adicionam-se os controladores suplementares POD no modelo modificado para os dispositivos TCSC e SSSC para verificar sua atuação. Para encontrar a melhor localização para instalação dos dispositivos é usado a teoria dos resíduos. Esta mesma teoria é usada também para o ajuste dos parâmetros dos controlares juntamente com outro ajuste feito através de Redes Neurais Artificiais (RNA), que é proposto como alternativa de comparação ao método dos resíduos. Simulações são efetuadas em um sistema teste simétrico para se verificar resultados e a eficácia do controlador POD (parâmetros ajustados pela RNA proposta), acoplados aos dispositivos FACTS, na manutenção da estabilidade a pequenas perturbações do SEP. Palavras-chave: Controladores POD. Estabilidade de sistema de potência. Redes neurais artificiais. TCSC e SSSC / Abstract: This work presents studies referred to short term Electric Power System (EPS) perturbations, considering the actuation of FACTS devices for low frequency electromechanical oscillation damping. The devices considered are: FACTS TCSC (Thyristor Controlled Series Capacitor) and the SSSC (Static Synchronous Series Compensator). It is representation and modeling FACTS devices in the EPS inserting in the Power Sensitivity Model. To improve the performance of the EPS considering the short term perturbations, additional controllers are proposed to increase the performance of the TCSC and SSSC devices, introducing the necessary damping to the EPS. The additional POD controller is added to the modified model for TCSC and SSSC devices to verify the acting. The residual theory is used to find the best location to install the devices. The same theory is used to adjust the parameters of the controllers and an adjustment with Artificial Neural Networks (ANN) is proposed as an alternative to the residual method. Simulations are effectuated for a symmetric test system to verify the efficiency of the POD controller (parameters adjusted by the ANN proposed), coupled with the FACTS devices, to maintain the stability considering the short term perturbations / Mestre

The final thesis analyzes the influence of high temperatures on the quality of the glued joints glued with hotmelt polyurethane adhesive. The panels of particle board were finished with ABS edge by using modern technology for edgebanding. The samples were tested in peel test performed at an angle of 90° and shear under compression loading at an angle of 45°. The experiment was carried out for samples stored in standard conditions and samples placed in conditions simulating the internal environment in standardized transport units in intermodal transport. Results were compared with each other, they were also compared with the results for the glued joints with hotmelt ethylene vinyl acetate adhesive.

EN: The misdemeanor of endangering under the influence of addictive substance is one of the most frequently occurring criminal offenses that the Czech society encounters. I have divided my thesis into nine chapters. The first chapter deals with elements of the criminal offense under the influence of addictive substance as divided by legal theory. The second chapter describes the issue of the unlawfulness of the deed. The third chapter deals with an analysis of qualifying circumstances that legislature provided in the second paragraph of the misdemeanor of endangerment under the influence of drugs. The fourth chapter describes the issue and the conditions of participation of persons other than the principal perpetrator of the deed. The sixth chapter deals with the most common criminal offenses that occur along with the abovementioned misdemeanor. The seventh chapter is devoted to the new phenomenon of proving a condition that excludes competence in cases of influencing other addictive substance. In the eighth chapter I focus on the issue of showing of various types of sentences with regard to current practice in relation to sentencing for the deed in question under Section 274 of the Criminal Code. The ninth chapter describes various forms of so-called special methods of proceedings which are used in the...

Nous étudions la déformation d'une capsule dans un canal microftuidique expérimentalement et numériquement. L'écoulement des rnicrocapsules est d'abord étudié numériquement dans un canal droit à section carrée. L'objectif est de développer une méthode de caractérisation des propriétés mécaniques de la membrane des capsules, à partir de leur déformation dans le canal. Nous avons mis en place une méthode d’identification afin de comparer la déformation des capsules observée expérimentalement et celle prédite par un modèle numérique tridimensionnel correspondant. La précision et la robustesse de l'algorithme d'analyse inverse ont été étudiées en faisant varier légèrement la géométrie des canaux. Finalement, la méthode a été utilisée afin de déterminer les propriétés mécaniques de rnicrocapsules dont la membrane est faite d’albumine réticulée. Nous avons ensuite appliqué une méthode de décomposition orthogonale aux valeurs propres (POD) aux formes prises par les capsules lors de leur passage dans un canal droit ou bifurqué. Des données numériques ont d 'abord été utilisées afin de déterminer la dimension de la variété des formes prises par une capsule dans un canal droit. La base POD ainsi construite a été utilisée pour interpoler les formes et obtenir la déformation d'une capsule à tous les temps, et pour tout paramètre d’écoulement. Nous avons également étudié expérimentalement les microcapsules lors de leur déformation dans un canal bifurqué. Nous avons ainsi obtenu les premiers résultats qualitatifs pour cette configuration. Nous avons développé un programme de détection de contour semi-automatique afin de faciliter le traitement d’image. Enfin, nous avons appliqué la méthode POD sur ces contours 2D réalistes et ainsi démontré la faisabilité d'utiliser une base réduite POD pour décrire la déformation de capsules clans un canal bifurqué. / The motion and deformation of a liquid-filled classic microcapsule flowing in microchannels is investigated bath experimentally and numerically. The flow of capsules into a straight microfluidic channel with a square cross-section is firstly studied. The objective is to develop a method to determine the mechanical properties of the capsule membrane from its hydrodynamic deformation. A method of identification has been devised to compare the particle deformed shape measured experimentally in the microchannels to the ones predicted by a three-dimensional numerical model for the same configuration. The precision and robustness of the inverse analysis algorithm have been tested when the microfluidic channels slightly depart from pure squareness. We have finally applied the method on microcapsules with a membrane made of reticulated albumin and determined their rnechanical properties. A Proper Orthogonal Decomposition (POD) has then been applied to the shapes assumed by the capsules while flowing in either a straight or bi­ furcated channel. Using numerical data in a straight channel, we have determined the dimension of the capsule shape variety. We have then interpolated the coefficients resulting from the POD analysis to compute the capsule deformed shape at any time for any flow parameter. Capsules have finally been investigated flowing in a bifurcated microchannel. Qualitative results of the motion and deformation of capsules in such channel have been obtained. A semi-automatic contour detection program has been developed to improve the image analysis. The POD method has been applied to the experimental results, thus proving the feasibility of building a reduced-order model of the phenomenon by using a POD reduced basis.

Solid lubricant coatings with controlled microstructures are good candidates in providing lubricity in moving mechanical assembly applications, such as orthopedics and bearing steels. Nanocrystalline ZnO coatings with a layered wurtzite crystal structure have the potential to function as a lubricious material by its defective structure which is controlled by sputter deposition. The interrelationships between sputtered ZnO, its nanocrystalline structure and its lubricity will be discussed in this thesis. The nanocrystalline ZnO coatings were deposited on silicon substrates and Ti alloys by RF magnetron sputtering with different substrate adhesion layers, direct current biases, and temperatures. X-ray diffraction identified that the ZnO (0002) preferred orientation was necessary to achieve low sliding friction and wear along with substrate biasing. In addition, other analyses such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) were utilized to study the solid lubrication mechanisms responsible for low friction and wear.

The influence of two lubricating and cleaning agents and diesel fuel on environmental stress cracking of polyamide reinforced by glass fibers and polycarbonate was studied in this master thesis. Testing of environmental stress cracking was performed by the method of critical bending deformation. Bergen elliptical strain jig was used for testing. The test liquids caused varying levels of environmental stress cracking of amorphous polycarbonate, but they did not cause environmental stress cracking of glass fiber reinforced polyamide. The test method used allows testing the resistance of both materials against environmental stress cracking of any liquid. The results can be used to design products that are expected to be exposed to corrosive liquids. Quantification of the influence of stress free corrosion on the static and impact properties of polycarbonate and glass fiber reinforced polyamide was performed by accelerated test. Specimens were exposed to test liquid and an elevated temperature of 70 °C. The mechanical properties of the tested materials were significantly affected by elevated temperature exposure. The yield strength of the polycarbonate has increased and the toughness has decreased due to physical aging. The tensile strength of glass fiber reinforced polyamide has increased due to a decrease of the moisture content of the material.

This work deals with study of swirling flows where the spiral vortical structure appears. The main relation is to flow seen in the draft tube cone of hydraulic turbines operated out of the design point (i.e. best efficiency point). In this cases large coherent vortex structure (vortex rope) appears and consequently high pressure pulsations are propagated to the whole machine system leading to possible restriction of turbine operation. This flow features are consequence of flow instability called vortex breakdown in case of Francis turbine operated at part load (flow rate lower than optimal one). The present study is carried out using simplified device of swirl generator in order to access similar flow conditions as can be found in real hydraulic turbines. Both the dynamic and dissipation effect of spiral vortex breakdown are investigated. The first part of thesis deals with spiral form of vortex breakdown. The experimentally measured velocity profiles (LDA) and wall static pressures are correlated with numerical simulations carried out using open-source CFD package OpenFOAM 2.2.2. The high speed camera recording of cavitating vortex core is used to obtain image ensemble for further post-processing. The dissipation effect of spiral vortex structure is in detail discussed based on computed flow fields. The second part of thesis is dedicated to the application of POD decomposition to the study of spatio-temporal features of spiral vortex dynamics. Firstly the POD is applied to the both the experimentally obtained image ensemble of cavitating vortex and numerically computed static pressure fields. Secondly the comprehensive analysis of spiral vortex mitigation effect by the axial water jet is analyzed. The collaborative study employing the swirl generator apparatus designed by the researchers from Politehnica University of Timisoara in Romania is performed and changes in spatio-temporal vortex dynamic are studied. In this study the numerical data (in a form of three-dimensional pressure and velocity fields) are obtained using commercial CFD software ANSYS Fluent R14.