No description available.

L'auto-organisation des organismes vivants est d'une complexité et d'une efficacité étonnantes. Plus précisément, les systèmes biologiques abritent un nombre gigantesque de réactions très spécifiques qui nécessitent que la bonne biomolécule se retrouve à la bonne place, dans le bon ordre et en un temps suffisamment court pour permettre le fonctionnement cellulaire, et au-delà la vie cellulaire. D'un point de vue dynamique, cela pose la question fondamentale de savoir comment les biomolécules trouvent efficacement leur(s) cible(s) spécifique(s), ou encore, quels types de forces rassemblent tous ces partenaires de réaction spécifiques dans un environnement aussi dense et ionisé que les micro-environnements cellulaires. Dans cette thèse, nous explorons la possibilité que des biomolécules puissent interagir à travers des interactions électromagnétiques de longue-portée telles que ces dernières sont prédites à partir des premiers principes de la physique; ''longue-portée'' signifiant que les interactionsen question sont actives sur des distances bien plus larges que les dimensions typiques des molécules mises en jeu (i.e., plus grandes qu'environ 50 angströms dans les systèmes biologiques). Après avoir posé les fondements théoriques concernant les interactionsde longue-portée potentiellement actives sur de longue distances dans un contexte biologique, nous étudions la posssibilité de détecter leur éventuelle contribution à partir de dispositifs expérimentaux qui sont accessibles de nos jours. Sur ce dernier point, des résultats préliminaires encourageants tant sur le plan théorique qu'expérimental sont présentés. / Self-organization of living organisms is of an astonishing complexity and efficiency. More specifically, biological systems are the site of a huge number of very specific reactions thatrequire the right biomolecule to be at the right place, in the right order and in a reasonably short time to sustain cellular function and ultimately cellular life. From the dynamic point of view, this raises the fundamental question of how biomolecules effectively find their target(s); in other words, what kinds of forces bring all these specific cognate partners together in an environment as dense and ionized as cellular micro-environments. In the present thesis, we explore the possibility that biomolecules interact through long-range electromagnetic interactions as they are predicted from the first principles of physics; "long-range" meaning that the mentioned interactions are effective over distances much larger than the typical dimensions of the molecules involved (i.e., larger than about 50 angströms in biological systems).After laying the theoretical foundations about interactions that are potentially active over long distances in a biological context, we investigate the possibility of detecting their contribution from experimental devices which are nowadays available. On the latter point, encouraging preliminary results both at the theoretical and experimental levels are exposed.

Die zerstörungsfreie Ultraschallprüfung von akustisch anisotropen Werkstoffen stellt auch heute noch eine Herausforderung dar. Die Gefügestruktur in solchen Materialien beeinflusst die Wellenausbreitung derart, dass es zum einen zu starken Streuungen durch die großflächigen Korngrenzen und zum anderen, aufgrund der akustischen Anisotropie, zu einer Richtungsabhängigkeit der Schallgeschwindigkeiten kommt. In den vergangenen Jahren wurden bereits Lösungsansätze zur mathematischen Modellierung der Schallausbreitung in anisotropen Materialien vorgestellt. Diese basieren in der Regel auf FEM- bzw. FIT- Algorithmen, die durch die Diskretisierung des gesamten Volumens einen hohen Rechenaufwand erfordern und in der täglichen Prüfpraxis aufgrund ihrer Komplexität bei der Parametrierung nur bedingt einsetzbar sind. Aus diesem Grund wird hier ein Ansatz zur Schallfeldberechnung gewählt, der auf die praktische Anwendung von Gruppenstrahler-Prüfköpfen zugeschnitten ist. Während sich andere Verfahren auf einzelne Wellenanteile und monofrequente Lösungen beschränken, um den Rechenaufwand zu reduzieren, können mit diesem Ansatz die reale Signalform des Prüfkopfes sowie alle auftretenden Wellenanteile in homogenen transversalisotropen Medien berücksichtigt werden. Durch entsprechende Optimierungen im Berechnungsalgorithmus lässt sich das gesamte vierdimensionale Schallfeld eines Gruppenstrahler-Prüfkopfes im Halbraum in kürzester Zeit berechnen. Die analytische Lösung der Wellengleichung für den Halbraum in Form einer Greenschen Funktion wird dabei in eine Gleichung umgeformt, die hier als vierdimensionale Punktrichtwirkung bezeichnet wird. Dieser Modellansatz ermöglicht es, die Parameter eines Gruppenstrahlersystems in der praktischen Anwendung zu überprüfen und durch iterative Rechnungen zu optimieren. Mit Hilfe einer einfach zu handhabenden Visualisierungstechnik ist es möglich diesen Modellansatz mit realen Schallfeldmessungen zu vergleichen. Dazu werden mit elektrodynamischen Sonden die einzelnen Komponenten des dreidimensionalen Vektors der Teilchenverschiebung an der Oberfläche von Festkörpern abgetastet. Die an den Messpunkten ermittelten Zeitfunktionen des Verschiebungsvektors werden dann dem berechneten Zeitverlauf der Wellenausbreitung gegenübergestellt. Die berechneten und gemessenen Schallfelder stimmen in der Phasenlage und im Amplitudenverlauf gut überein. Die Ergebnisse zeigen, dass mit dem verwendeten Rechenmodell alle in der Realität auftretenden Wellenanteile vollständig berücksichtigt werden und dreidimensionale Problemstellungen aus der Praxis mit diesem Modell korrekt berechnet werden können. / The non-destructive ultrasonic testing of acoustic anisotropic materials is an important challenge. The texture of these materials causes a strong scattering of the sound wave by the extensive grain boundaries and a direction dependent sound velocity by the acoustic anisotropy. Several approaches for the modelling of the sound propagation in anisotropic materials were presented in the last years. These approaches are normally based on FEM or FIT algorithms using a discretisation of the complete volume. Their calculation needs extensive time and a very complex parameterisation. Thus these algorithms are not suitable in practice of ultrasonic testing. In this work an approach is presented that is optimised for the application of phased array transducers. The new approach considers the real frequency spectrum of the transducer as well as all occurring wave modes in homogeneous transversely isotropic media, whereas other approaches are limited to solutions for single wave modes and single frequencies to reduce the calculation effort. The appropriate optimisations of the mathematical algorithm allow the fast calculation of the complete four-dimensional transient wave field of a phased array transducer in the half-space. The Green’s functions are derived by an analytical solution of the elastodynamic wave equation for the half-space. These functions will be transformed into an equation which will be referred to in this work as four-dimensional directivity pattern. This approach allows the verification of the parameters of a phased array system and their optimisation by iterative calculations in the practical application. To get accurate results in these calculations, the experimental verification of the applied mathematical model for the wave propagation is an essential task. The technique presented in this work applies electrodynamic probes, which provides a simple use. The probes can detect the particle displacement at a solid surface in all three spatial directions. The measured time-functions of the wave field will be compared with the calculated time-functions. They show a good accordance in the phase and the amplitude. This confirms that the applied mathematical model considers completely all in practice occurring wave modes. The results further show that three-dimensional problems in practice can be calculated correctly with this model.

An analysis using numerical methods can calculate electrical and construction characteristics parameters of microwave devices quite accurately. However, numerical methods require a lot of computation resources and time for calculations to be made. Rapid perfection of the computer technologies and software with implementation of the numerical methods has laid down the conditions to the rapid design of the microwave devices using computers. / Disertacijoje nagrinėjamos mikrobangų įtaisų analizės ir sintezės proble-mos, taikant lygiagrečiąsias kompiuterines sistemas. Pagrindiniai tyrimo objektai yra daugialaidės mikrojuostelinės linijos ir meandrinės mikrojuostelinės vėlinimo linijos. Šie objektai leidžia perduoti, sinchronizuoti bei vėlinti siunčiamus signalus ir yra neatsiejama dalis daugelio mikrobangų prietaisų. Jų operatyvi ir tiksli analizė bei sintezė sąlygoja įtaisų kūrimo spartinimą. Pagrindinis disertacijos tikslas – sukurti lygiagrečiąsias metodikas ir algoritmus, skirtus sparčiai ir tiksliai atlikti minėtų linijų analizę ir sintezę. Sukurtų algoritmų ir metodikų taikymo sritis – mikrobangų įtaisų modeliavimo ir automatizuoto projektavimo progra-minė įranga.

Disertacijoje nagrinėjamos mikrobangų įtaisų analizės ir sintezės proble-mos, taikant lygiagrečiąsias kompiuterines sistemas. Pagrindiniai tyrimo objektai yra daugialaidės mikrojuostelinės linijos ir meandrinės mikrojuostelinės vėlinimo linijos. Šie objektai leidžia perduoti, sinchronizuoti bei vėlinti siunčiamus signalus ir yra neatsiejama dalis daugelio mikrobangų prietaisų. Jų operatyvi ir tiksli analizė bei sintezė sąlygoja įtaisų kūrimo spartinimą. Pagrindinis disertacijos tikslas – sukurti lygiagrečiąsias metodikas ir algoritmus, skirtus sparčiai ir tiksliai atlikti minėtų linijų analizę ir sintezę. Sukurtų algoritmų ir metodikų taikymo sritis – mikrobangų įtaisų modeliavimo ir automatizuoto projektavimo progra-minė įranga. / An analysis using numerical methods can calculate electrical and construction characteristics parameters of microwave devices quite accurately. However, numerical methods require a lot of computation resources and time for calculations to be made. Rapid perfection of the computer technologies and software with implementation of the numerical methods has laid down the conditions to the rapid design of the microwave devices using computers.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work presents contributions to the sinusoidal acceleration control of electrodynamic shakers applied in vibration testing. Considering the importance of sine tests to identify critical frequencies of operation and to determine mechanical weakness in the specified performance of specimens, vibration controllers are designed to reproduce the amplitude and the frequency of the reference acceleration specifically at the interface between the shaker and the structure under test. Two distinct approaches are considered to solve the control problem: time domain control, where the acceleration instantaneous value is adjusted to track the sinusoidal reference, and frequency domain control, in which only the amplitude or the root mean square value of the acceleration is compensated to follow the reference magnitude. The solutions developed based on these two different approaches are implemented in a digital control platform and experimentally evaluated. The development of vibration controllers is complemented by contributions to the study of the shaker dynamic model, as well as to the instrumentation applied to measure and feedback the acceleration and to the voltage control of switching-mode power amplifiers designed to drive the shaker. Regarding the vibration machine dynamic model, a method is proposed to experimentally identify the mechanical parameters of a two degrees of freedom system that represents the suspension resonance and the finite armature stiffness of the electrodynamic shaker. A procedure is developed to design and implement charge mode preamplifiers and signal conditioning circuits for piezoelectric accelerometers. A robust model reference adaptive algorithm is applied to control the output voltage of an industrial switching-mode power amplifier. The experimental analysis of the adaptive controller considers not only the improvements on the power amplifier performance, but also the of impact over the behavior of a commercial digital vibration control system. / Este trabalho apresenta contribuições ao controle de aceleração senoidal de vibradores eletrodinâmicos utilizados em ensaios de vibração. Considerando a importância de testes com aceleração senoidal para identificar freqüências críticas de operação e determinar a resistência de materiais e estruturas, são desenvolvidos controladores para a máquina de vibração com o propósito de garantir que a amplitude e a freqüência da aceleração imposta à estrutura sob teste correspondam aos valores de referência. Na solução do problema, admitem-se duas abordagens distintas: controle no domínio do tempo, onde o valor instantâneo da aceleração é ajustado para seguir a referência senoidal, e controle no domínio da freqüência, no qual apenas a amplitude ou o valor eficaz da aceleração é regulado conforme a magnitude de referência. As técnicas propostas com base nestas abordagens são implementadas numa plataforma de controle digital e avaliadas experimentalmente. O desenvolvimento dos controladores de vibrações é complementado por contribuições ao estudo do modelo dinâmico do vibrador, à instrumentação aplicada para realimentar a aceleração e ao controle da tensão de amplificadores de potência que utilizam inversores com modulação por largura de pulso para acionar a máquina. Com relação ao modelo do vibrador, é descrito um método que permite determinar experimentalmente os parâmetros mecânicos de um modelo com dois graus de liberdade, o qual representa o comportamento da máquina devido à suspensão e à rigidez finita da armadura. Um procedimento de projeto e realização prática de pré-amplificadores de carga e de um circuito de condicionamento para acelerômetros piezoelétricos é apresentado. Um algoritmo adaptativo robusto por modelo de referência é avaliado no controle da tensão de saída de um amplificador industrial projetado para excitar o enrolamento da armadura do vibrador. A análise experimental do impacto do controlador adaptativo é realizada considerando não apenas a melhoria no desempenho do amplificador, mas também em termos dos reflexos na performance de uma plataforma comercial de controle de ensaios de vibrações.

The increasing complexity with the decrease in size of EEE – components (Electronic, electric and electromagnetic) raises the question on how higher energy frequencies will affect the components and their continuous development. The most common vibration testing equipment currently in use within the automotive industry and SCANIA CV AB are the electrodynamic shaker (ED system). This thesis covers the characteristics of different vibration testing equipment while analysing their strengths and weaknesses, not only for the automotive industry but also including equipment more commonly handled within the aero and space industry. The project aims to find a complement for the ED system and study the possibility for its replacement in the automotive industry.In particular, experiments are carried out and documented on a so-called “Repeatable shaker system” (RS system) for the purpose to get a better understanding on the functions of the equipment and its overall differences compared to the electrodynamic system when it comes to random vibration testing.It became clear that complementing or replacing the ED system is difficult and that the RS system work fundamentally different in comparison. Accordingly, the RS system is not a potential replacement for our purpose and it cannot perform at the same level of precision but instead is able to achieve higher energy frequencies overall, making it still ideal for its intended purposes, but not as a replacement of the ED system.

In the introduction a traction circuit is analyzed with different types of electric devices. The thesis describes power railway electric circuits, their loads and types of used contactors. Railway standards chapter summarizes requirements of standards for railway contactors. Follows literature focusing on power current switching and power switching devices design. Based on previous, a design procedure is developed for railway MV contactor in accordance with end-user and standards requirements. Thesis closes with pre-designing a railway contactor by calculating electrodynamic forces, heatflow and mechanical components.

This master's thesis deals with data processing for an electrodynamic test bench. The thesis presents a theoretical overview of signal distribution, determination of fatigue damage from random vibrations and a description of test benches. The next part deals with setting up the test time reduction in GlyphWorks software. The aim of this thesis is to process and create a procedure for an accelerated fatigue test from data measured during an operational test on a polygon. The data are then verified on an electrodynamic test rig using a Skoda Auto dynamic test room. The final part of the thesis contains data evaluation and a guide explaining how to easily create a test in the relevant software.

The thesis deals with power harvesting sensors as a source of energy. As the power requirements for microelectronics decreases the environmental energy sources become more perspective. In a few last years batteries reach a higher capacity but there is still problem with their replacement. Power harvesting sensors appears as a good solution for powering microelectronics.