Bombas de fluxo são dispositivos importantes em áreas como a Bioengenharia, Medicina, Farmácia, entre outras aplicações clássicas de Engenharia. Princípios para o bombeamento de fluidos baseados em atuadores piezelétricos estão sendo estudados no Departamento de Engenharia Mecatrônica e de Sistemas Mecânicos da Escola Politécnica, que permitem a construção de bombas de fluxo de pequena escala, ou seja, bombas de fluxo de pequena potência para deslocamento de pequenos volumes de fluido com baixo consumo de energia. O presente trabalho estuda bombas de fluxo piezelétricas de diafragma do tipo valve-less para geração de vazão. A bomba de fluxo piezelétrica de diafragma utiliza cerâmica piezelétrica como atuador para mover uma membrana (diafragma) para cima e para baixo como um pistão, que causa uma seqüência de aumento e diminuição do volume da câmara da bomba, forçando a entrada e a saída do fluido na bomba. A direção do fluxo é garantida por válvulas que privilegiam o fluxo em apenas um sentido. O objetivo deste trabalho é o estudo da metodologia de desenvolvimento de uma bomba de fluxo piezelétrica de diafragma de baixo custo do tipo valve-less. Para tanto, será utilizado a modelagem por Método dos Elementos Finitos (MEF) para a realização de análises de sensibilidade dos parâmetros geométricos e construtivos da bomba de fluxo. Serão realizadas simulações de escoamento de fluido pelo Método de Volumes Finitos (MVF) para a realização de análises de sensibilidade dos parâmetros geométricos dos elementos difusor/bocal e o levantamento das curvas características da bomba de fluxo. Por fim, protótipos serão construídos e caracterizados para validação dos resultados computacionais. Serão apresentadas a metodologia empregada e a discussão dos resultados obtidos, de forma a analisar o princípio proposto e os fenômenos físicos em questão. / Flow pumps act as important devices in areas as Bioengineering, Medicine, Pharmacy, among other areas of Engineering. Principles for pumping fluids based on piezoelectric actuators have been studied in the Department of Mechatronic and Mechanical Engineering of Escola Politécnica da Universidade de São Paulo, that allow the construction of small flow pumps, in other words, pumps for displacement of small fluid volumes with low power consumption. The present work studies valveless piezoelectric diaphragm flow pumps for flow generation. The piezoelectric diaphragm flow pump uses a piezoelectric ceramic as actuator to move a membrane (diaphragm) up and down as a piston. Consequently, there is a sequence of increase and decrease in the chamber volume that will force the fluid in and out of the pump. The direction of the flow is guaranteed by valves that privilege the flow in just one pumping direction. The main objective of this work is the study of a methodology to develop a low cost valve-less piezoelectric diaphragm flow pump. A sensitivity analysis is carried using computational simulation through the Finite Element Method (FEM) to study how construction parameters and assembly affect diaphragm flow pump performance. Using CFD simulations through the Finite Volume Method (FVM), a sensitivity analysis is done around nozzle/diffuser element geometrical parameters and pump characteristic curves are obtained. Finally, computational results are validated by prototype construction and characterization. The text presents methodologies employed and discusses the obtained results, analyzing the principle and the related physical phenomena.

Digital holographic microscopy is an interferometric imaging technique, the principle of which is the off-axis image plane holography. The principle of this technique enables to reconstruct both the image intensity and the image phase from the output interferencesignal. The reconstruction can be carried out on the basis of a single image plane hologram. This leads to the possibility of a realtime image reconstruction. The speed of the reconstruction depends on the detection and the computing process. The aim of this diploma thesis is to develop user software for the control of the detection camera and for the image plane hologram reconstruction. The effort was to achieve the highest number of image reconstructions per time unit, with the maximum utilization of the data transfer between the camera and the computer.The next aim of this thesis is the stabilization of the optical table position. The method of stabilization is based on the image phase information, which is used for the control loop feedback between reconstructed image phase and the piezoelectric actuator placed inside of the optical table. Experimental results, which prove the functionality of the stabilization, are presented.

This thesis presents the design and development of two switching amplifiers used to drive the so-called smart material actuators. Different from conventional circuits, a smart material actuator is ordinarily a highly capacitive load. Its capacitance is non-linear and its strain is hysteretic with respect to its electrical control signal. This actuator's reactive load property usually causes a large portion of reactive power circulating between the power amplifier and the driven actuator, thus reduces the circuit efficiency in a linear power amplifier scenario. In this thesis, a switching amplifier design based on the PWM technique is proposed to develop a highly efficient power amplifier, and peak current mode control is proposed to reduce the actuator's hysteretic behavior. Since the low frequency current loop gain tends to be low due to the circuit's capacitive load, average current mode control is further proposed to boost the low frequency current loop gain and improve the amplifier's low frequency performance. Both of the circuits have been verified by prototype design and their experimental measurement results are given. / Master of Science

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Smart foam is a composite noise control treatment that consists of a distributed piezoelectric actuator, known as polyvinylidene fluoride (PVDF), embedded within a layer of partially-reticulated polyurethane foam. The principal function of smart foam is to yield broadband sound attenuation. Passive acoustic foams are a very reliable high-frequency sound reduction method. With regard to smart foam, the embedded piezoelectric actuator is introduced to overcome the limitations of the passive foam in the low-frequency region. The piezoelectric actuator excites the structural and acoustic phases of the foam when driven by an externally supplied control voltage. This generates a secondary acoustic field which destructively interacts with the acoustic field created by a primary noise source. Initial experiments employ the composite "active/passive" treatment to yield attenuation of piston sound radiation. For this simple source, the global farfield pressure is minimized according to the feedforward, Filtered-x LMS control algorithm using one error sensor. Significant broadband sound attenuation is obtained. A more advanced noise control problem is investigated which minimizes plate radiation. The vibrating plate has a distributed modal response requiring a collective array of independently-phased smart foam actuators to yield reduction of the radiated sound power. This is accomplished by minimizing the sound pressure at an array of nearfield microphones. Good broadband sound power reduction is obtained using a MIMO (multiple-input/multiple-output) Filtered-x LMS control scheme. Various techniques for improving smart foam's acoustic control authority are identified during manufacturing and finite element modeling. of the actuator. These improved smart foam actuators are employed as an active/passive liner to suppress the transverse propagating acoustic modes within an anechoically-terminated rectangular duct. A section of a duct wall is lined with an array of smart foam and the sound downstream of the control actuators is minimized at several error microphones. Successful harmonic and broadband noise control is achieved. A full-scale numerical model of the duct acoustic control application is presented based on the finite element method. The purpose of the model is to study the sensitivity of this active/passive control approach relative to the spatial distribution of control channels and error sensors. A comparison of the numerical and experimental results yields similar trends. / Ph. D.

High-bandwidth fuel modulation is currently one of the most promising methods for active combustion control. To attenuate the large pressure oscillations in the combustion chamber, the fuel is pulsed so that the heat release rate fluctuations damp the pressure oscillations in the combustor. This thesis focuses on the development and implementation of a high-bandwidth, proportional modulation system for liquid-fuel active combustion control. The throttle valve modulation system, discussed in this thesis, uses a 500-um piezoelectric stack coupled with an off-the-shelf valve. After comparing three other types of actuators, the piezoelectric stack was selected because of its compact size, bandwidth capabilities, and relatively low cost. Using the acoustic resonance of the fuel line, the system is able to achieve 128% pressure modulation, relative to the mean pressure, and is capable of producing more than 75% flow modulation at 115 Hz. Additionally, at 760 Hz the system produces 40% pressure modulation and 21% flow modulation with flow rates between 0.4 and 10 gph. Control authority was demonstrated on a single-nozzle kerosene combustor which exhibits a well-pronounced instability at ~115 Hz. Using the modulation system, the fundamental peak of the combustion instability was reduced by 30 dB, and the broadband sound pressure levels inside the combustor were reduced by 12 dB. However, the most important conclusion from the combustion control experiments was not the system?s accomplishments, but rather its inability to control the combustor at high global equivalence ratios. Our work indicates that having the ability to modulate a large percentage of the primary fuel is not always sufficient for active combustion control. / Master of Science

Este trabalho apresenta o projeto de pesquisa desenvolvido para a obtenção do título de Mestre em Engenharia Elétrica, na área de concentração de engenharia de sistemas, da Escola Politécnica da Universidade de São Paulo. O principal objetivo deste trabalho foi o desenvolvimento de um sistema de acionamento (driver) para os atuadores piezoelétricos do interferômetro de Fabry-Pérot do espectrômetro BTFI (Brazilian Tunable Filter Imager), um instrumento visitante do telescópio SOAR (Southern Astrophysical Research Telescope), no Chile. O Fabry-Pérot é um instrumento óptico composto de duas superfícies paralelas altamente reflexivas (espelhos), cuja distância é controlada por um sistema de nanoposicionamento composto de três atuadores piezoelétricos (piezos) do tipo APA® (Amplified Piezoelectric Actuators) e um sistema de medida capacitivo. O principal requisito técnico de desempenho do sistema de nanoposicionamento do Fabry-Pérot é tal que o ruído de posicionamento dos espelhos deve ser limitado a 3 . No entanto, os fenômenos não lineares de histerese e escorregamento (creep) dos piezos limitam a precisão de posicionamento do sistema de controle, razão pela qual foi desenvolvido um sistema de acionamento por carga e tensão para os piezos, com o intuito de atenuar suas não linearidades e, consequentemente, melhorar o desempenho do sistema de controle em malha fechada, em termos de ruído de posicionamento. A primeira etapa deste trabalho consistiu da caracterização do modelo e da instrumentação do sistema de nanoposicionamento do Fabry-Pérot, composto de sensores capacitivos, conversores de sinal, atuadores piezoelétricos e sistema de aquisição de dados. Após a caracterização dos componentes do sistema, sua especificação técnica de desempenho de 3 foi traduzida em requisitos de engenharia para o projeto do sistema eletrônico de acionamento dos piezos por carga e tensão, notadamente em termos de ruído, tempo de resposta, banda de resposta em frequência, ganho, corrente e tensão elétricas e dissipação de potência. Uma vez concluído o projeto do driver, um protótipo foi implementado e testado com o sistema real, a fim de se verificar experimentalmente a atenuação dos efeitos não lineares. Finalmente, foram realizados alguns experimentos com o driver e o sistema de nanoposicionamento em malha fechada, controlado por um compensador PI, a fim de se verificar a influência da atenuação das não linearidades dos piezos nesta configuração. Após a análise dos resultados experimentais obtidos, verificou-se que o ruído de posicionamento do sistema, em malha fechada, é significativamente menor quando os fenômenos não linearidades dos piezos são atenuados. / This work represents the research project to obtain the degree of Master of Sciences in Electrical Engineering, specializing in Systems Engineering, at the Escola Politécnica da Universidade de São Paulo, in São Paulo, Brazil. The main objective of this project was to design an electronic power driver for the piezoelectric actuators of the Fabry-Pérot interferometer of the BTFI spectrometer, a visitor instrument of the SOAR telescope, in Chile. Fabry-Pérot is an optical instrument composed by two high reflexive parallel surfaces (mirrors), which distance is controlled by a nanopositioning system composed by three piezoelectric actuators (piezos) of the class APA® (Amplified Piezoelectric Actuators) and a capacitive measurement system. The main performance specification of the Fabry-Pérots nanopositioning system is such that the positioning noise must be limited to 3 . However, the nonlinear behaviors (hysteresis and creep) of the piezos limit the positioning precision of the control system, for which reason a charge and voltage actuation system was developed for the piezos, in order to mitigate its nonlinearities and, consequently, improve the performance of the control system in closed loop, in terms of positioning noise. The first step in this work consisted on the characterization of the Fabry-Pérot nanopositioning systems model and instrumentation, which are composed by capacitive sensors, signal converters, piezoelectric actuators and a data acquisition board. After the characterization of the components of the nanopositioning system, the 3 specification was interpreted to low level engineering requirements for the design of the charge and voltage driver, especially in terms of noise, response time, frequency bandwidth, gain, electrical current, voltage and power dissipation. Once concluded the design of the driver, a prototype was implemented and tested in the real system, in order to verify the attenuation of the nonlinear effects. Finally, some experiments with the driver and the nanopositioning system were performed in closed loop, controlled by a PI compensator, in order to verify the influence of the attenuation of the nonlinearities of the piezos in such configuration. The analysis of the obtained experiment results showed that the nanopositioning systems noise, in closed loop, is significantly reduced when the nonlinear effects of the pizeos are attenuated.

La maîtrise de la température des composants à forte dissipation, notamment dans les systèmes électroniques nomades, constitue un verrou à leurs développements. Que ce soit pour l'électronique de puissance ou les calculateurs, les densités de puissance requièrent l'utilisation de systèmes de refroidissement de plus en plus performants, en particulier dans le cas des microprocesseurs qui associent miniaturisation et augmentation des fréquences d'horloge. Les conséquences sont multiples, limitation des performances, augmentation de la consommation et du taux de défaillance. C'est dans ce contexte que le projet CANOPEE, réunissant un consortium de partenaire industriel et académique, propose de développer et démontrer les avantages d'une solution technologique active récemment brevetée et appelée OnduloTrans. Elle consiste en un dispositif échangeur-pompe, permettant à la fois d'obtenir un excellent transfert thermique et d'assurer le pompage du fluide caloporteur. OnduloTrans est une solution active de refroidissement basée sur la déformation dynamique d'une paroi d'un canal. Le dispositif est fixé directement à l'aplomb du composant à refroidir. Le canal est déformé suivant une onde progressive pour créer un pompage péristaltique. L'intensification des transferts est obtenue lorsque les variations dynamiques des dimensions du canal viennent perturber la couche limite à l'interface conduction/convection. Le travail de la thèse consiste à concevoir et développer une solution d'actionnement intégrée permettant de mouvoir la paroi souple. Il s'accompagnera d'essais concrets témoignant des performances thermiques de cette solution. L'actionnement mis en oeuvre doit respecter les contraintes hydrauliques et thermiques de l'application embarquée visée, tout particulièrement le faible encombrement et une consommation électrique minimale. La difficulté réside dans les critères antagonistes que sont la production d'une onde progressive de grande amplitude dans un milieu aux dimensions centimétriques. Le manuscrit s'articule en trois parties. Dans un premier temps les solutions d'actionnement envisageables seront explorées. Pour ce faire, la solution OnduloTrans est d'abord décrite. Un état de l'art des solutions de conversion électromécanique, puis des micropompes péristaltiques est entrepris. Les phénomènes hydrauliques propres au micropompage péristaltique sont abordés pour cerner la problématique du développement de l'actionnement. Ensuite les deux chapitres suivants détaillent l'étude de deux solutions piézoélectriques distinctes. Une première solution piézoélectrique à onde discrète est développée dans le second chapitre. Elle consiste en une répartition d'actionneurs flextensionnels le long de la paroi souple. Une méthodologie de prédimensionnement basée sur des modèles mécaniques simples est présentée. L'onde progressive créée étant très particulière, une méthode analytique de calcul du débit, validée par simulations numériques, permet d'étudier l'influence de la commande des actionneurs. Un prototype est finalement réalisé avec l'aide des partenaires. De nombreux essais sont ensuite réalisés afin de valider les différentes hypothèses et déterminer les premières performances hydrauliques et thermiques du dispositif. Le troisième chapitre aborde une solution à onde progressive continue et actionnement intégré à la membrane. Le but est ici de prouver le concept de pompage péristaltique par flexion contrôlée d'une plaque intégrant une couche piézoélectrique. Un modèle de dimensionnement 1D constitué de tronçons piézoélectriques répartis à la surface est tout d'abord présenté. La répartition des segments piézoélectriques fait ensuite l'objet d'une étude paramétrique afin de définir judicieusement leur disposition, ceci en vue de maximiser le débit théorique. Cette étude paramétrique est finalement couplée à une optimisation des commandes électriques, évaluée par les résultats d'un prototype. / Controlling the temperature of components with high thermal dissipation is a constraining factor in their developments, especially in embedded electronic systems. Power density, whether in computing or power electronics, requires the use of ever more efficient cooling systems. This is especially true for microprocessors in which increasingly miniaturization and clock frequency are combined. Consequently, without the adequate cooling, the performance is severely limited and its power consumption increased as well as the failure rate. In this challenging context a consortium of industrial and academic partners created the CANOPEE project. CANOPEE focus is to develop and prove the advantages of a recently patented solution called OnduloTrans. The solution is an exchanger-pump device, ensuring at the same time an excellent heat transfer and the pumping of the coolant. OnduloTrans is an active cooling solution based on the dynamic deformation of a thin wall. This deformation is in the manner of a pseudo travelling wave to satisfy a peristaltic pumping. The device is fixed directly above the component to be cooled, thus the liquid flows on its surface. The enhancement in heat transfer is obtained when the dynamic variations of the channel thickness disturb the boundary layer near the conduction / convection interface. The purpose of this thesis was to study the capability of such active pumping system and to design an integrated actuation solution to move the flexible wall. It will result to experimental tests showing the thermal performance of this solution. The implemented actuation system must respect the constraints for on-board applications, especially compactness and minimal power consumption. The challenge stands in the trade-off between the production of a large amplitude travelling wave and the limited volume available. The manuscript is divided into three parts. Initially, the different actuation solutions will be explored. To do this, the OnduloTrans solution is first described. Then, a state of the art of electromechanical conversion solutions and peristaltic micropumps is undertaken. After that, the specific hydraulic phenomena involved in peristaltic micropumps are discussed to determine the difficulties in the development of such actuation system. Then the two next chapters detail the study of two distinct piezoelectric solutions. A discrete wave piezoelectric solution is presented in the second chapter. It consists of a distribution of flextensional actuators along the flexible wall. A pre-dimensioning methodology based on simple mechanical models is presented. The created wave is very particular, so an analytical method is developed to evaluate the flow rate and making possible to study the impact of the actuator control strategy. This algorithmic method is validated by comparison with finite element numerical simulations. A prototype is finally made with the support of partners. Several tests are then carried out in order to validate the hypotheses and evaluate the preliminary hydraulic and thermal performances of the prototype. The third chapter addresses a continuous travelling wave solution and an actuation system integrated into the membrane. The purpose here is to prove the concept of peristaltic pumping by controlled bending of a plate incorporating a piezoelectric layer. A 1D dimensioning model consisting of piezoelectric segments distributed on the surface is first presented. The distribution of the piezoelectric segments is then the subject of a parametric study to judiciously define their arrangement, in order to maximize the theoretical flow. This parametric study is finally coupled with an optimization of electrical controls, and compared to the experimental results of a prototype.