The contact between the tire and the road is the key enabler of vehicle acceleration, deceleration and steering. However, under the circumstances of sudden changes to the road conditions, the driver`s ability to maintain control of the vehicle maybe at risk. In many cases, this requires intervention from the chassis control systems onboard the vehicle. Although these systems perform well in a variety of situations, their performance can be improved if a real-time estimate of the tire-road contact parameters (ranging from kinematic conditions of the tire to its dynamic properties) are available. At the present stage of development, tire-road contact parameters are indirectly estimated using observers based on vehicle dynamics measurements (acceleration, yaw and roll rates, suspension deflections, etc). Although these methods present a relatively accurate solution, they rely heavily on tire and vehicle kinematic formulations and break down in case of abrupt changes in the measured quantities. To address this problem, researchers have been developing certain sensor based advanced tire concepts for direct measurement of the tire-road contact parameters. Thus the new terms "Intelligent Tire" and "Smart Tire", which mean online tire monitoring are thus enjoying increasing popularity among automotive manufacturers and formed the motivation for this thesis to explore the possibility of developing an intelligent tire system. The development of the so called "intelligent tire/ smart tire system" is expected to spur the development of a new generation of vehicle control system with modified control strategies, leveraging information directly coming from the interface between the tire and the road, and in turn significantly reducing the risk of accidents. The specific contributions of this thesis include the following: • Development of an intelligent tire system, with a special attention to development of measurement and sensor feature extraction methodologies of acceleration signals coming from sensors fixed to the tire innerliner • Design of an integrated vehicle state estimator for application to global chassis control • Development of a model-based tire-road friction estimation algorithm • Development of an intelligent tire based adaptive wheel slip controller for anti-lock brake system (ABS) • Development of a piezoelectric vibration energy harvesting system with an adaptive frequency tuning mechanism for intelligent tires / Master of Science

Despite the many attractive features of carbon fiber reinforced polymers (FRPs) composites, they are prone to failure due to delamination. The ability to tailor the fiber/matrix interface FRPs is crucial to the development of composite materials with enhanced structural performance. In this dissertation, ZnO nanowires (NWs) were grown on the surface of carbon fibers utilizing low temperature hydrothermal synthesis technique prior to the hybrid composite fabrication. The scanning electron microscopy revealed that the ZnO nanowires were grown uniformly on the surface of the carbon fabric. The surface grown ZnO NWs functionally-graded the composite material properties and ensured effective load transfer across the interface. To assess the influence of the ZnO NWs growth, reference samples were also prepared by exposing the carbon fabric to the hydrothermal conditions. The damping properties of the hybrid ZnO NWs-CFRP composite were examined using the dynamic mechanical analysis (DMA) technique. The results showed enhanced energy dissipation within the hybrid composite. Quasi-static tensile testing revealed that the in-plane and out-of-plane strengths and moduli of the hybrid FRP composite were also boosted. The interlaminar shear strength (ILSS) measurements suggested the improvement in the mechanical properties of the composite to the enhanced adhesion between the ZnO nanowires and the other constituents (carbon fiber and epoxy). It was necessary thus, to utilize the molecular dynamics simulations (MD) to investigate the adhesion within the CFRP structure upon growing the ZnO nanowires on the surface of the carbon fibers. Molecular models of the carbon fibers, the epoxy matrix and the ZnO nanowires were built. The resulting molecular structures were minimized and placed within a simulation box with periodic boundary conditions. The MD simulations were performed using the force field COMPASS to account for the empirical energy interactions between the different toms in the simulation box. Proper statistical thermodynamics were employed to relate the dynamics of the molecular model to the macroscale thermodynamic states (pressure, temperature and volume). Per the computed potential energies of the different components of the composite, it was found that the polar surfaces in the ZnO structures facilitates good adhesion properties in the graphite-epoxy composite. Besides the attractive mechanical properties of the ZnO nanowires, their piezoelectric and semiconductor properties were sought to design an energy harvesting device. To ensure sufficient charges collection from the mechanically stressed individual ZnO nanowires, a copper layer was sputtered on top of the ZnO nanowires which introduced also a Schottky effect. The mechanical excitation was provided by exposing the device to different vibration environment. The output voltage and currents were measured at the conditions (in terms of frequency and resistive load). It was demonstrated that the electrical output could be enhanced by stacking up similar devices in series or in parallel. Finally, in an attempt to exploit the reversibility of the electromechanical coupling of the energy harvesting device, the constitutive properties of the hybrid ZnO nanowires-CFRP composite were estimated using the Mori-Tanaka approach. This approach was validated by a finite element model (FEM). The FEM simulations were performed on a representative volume element (RVE) to reduce the computational time. The results demonstrated that the mechanical properties of the hybrid ZnO NWs-CFRP composite were better than those for the baseline CFRP composite with identical carbon fiber volume fraction (but with no ZnO NWs) which confirmed the experimental findings. Furthermore, the electro-elastic properties of the hybrid composite were determined by applying proper boundary conditions to the FE RVE. The work outlined in this dissertation will enable significant advancement in the next generation of hybrid composites with improved structural and energy harvesting multifunctionalties. / Ph. D.

[pt] Nos últimos anos, tem-se observado um interesse crescente em estruturas multiestáveis. Sistemas com múltiplas configurações de equilíbrio estável geralmente são obtidos através de uma cadeia de unidades biestáveis conectadas por elementos rígidos ou flexíveis. Entretanto, pouco se sabe sobre seu comportamento estático e dinâmico não linear. Neste trabalho realiza-se uma análise não linear estática e dinâmica detalhada de sistemas multiestáveis formados por duas unidades biestáveis abatidas, especificamente, duas treliças de von Mises ou dois arcos, conectados em ambos os casos por elementos rígidos ou flexíveis. Para isto, as equações não lineares de equilíbrio e de movimento são obtidas através do princípio da energia potencial estacionária e do princípio de Hamilton, respectivamente, considerando um material elástico linear. Utilizando algoritmos de continuação, os caminhos de equilíbrio são obtidos e a estabilidade analisada utilizando o princípio da energia potencial mínima. Múltiplos caminhos de equilíbrio são identificados, levando a múltiplas soluções coexistentes, estáveis e instáveis, e vales potenciais intimamente ligados às simetrias dos sistemas. O efeito das inevitáveis imperfeições iniciais é também esclarecido. As oscilações não lineares e as bifurcações dos sistemas sob carregamento harmônico são estudadas através de diagramas de bifurcação, mapas de Poincaré e bacias de atração. Estuda-se também o efeito do pré-carregamento estático na dinâmica global. Observam-se, em virtude de sequências de bifurcações emergindo de cada posição de equilíbrio estável, um elevado número de soluções coexistentes, periódicas e aperiódicas, levando a bacias de atração complexas e com amplas regiões fractais. Por um lado, estes cenários podem ser valiosos em diversas aplicações. Por outro, múltiplos atratores e suas bacias fractais podem levar à perda da estabilidade e integridade dinâmica. Desta forma, o conhecimento do comportamento estático e dinâmico não linear de sistemas multiestáveis é imprescindível em qualquer aplicação em engenharia. Como exemplo de aplicação, se utiliza um sistema formado por treliças de von Mises no processo de coleta de energia através de elementos piezoelétricos. O comportamento altamente não linear resulta em movimentos de grande amplitude para largas faixas de excitação, aumentando sua eficiência e aplicabilidade. / [en] In the last years, an increasing interest in multistable structures has been observed. Multistable systems are generally attained by a chain of bistable units connected by rigid or flexible elements. However, little is known about their nonlinear static and dynamic responses. In this work, a detailed nonlinear static and dynamic analysis of multistable systems formed by two shallow bistable units is conducted, specifically, two von Mises trusses or two arches, connected in both cases by rigid or flexible elements. For this, the nonlinear equilibrium equations and equations of motion are obtained through the principle of stationary potential energy and Hamilton s principle, respectively, considering a linear elastic material. Using continuation algorithms, the nonlinear equilibrium paths are obtained, and stability analyzed using the principle of minimum potential energy. Multiple equilibrium paths are identified, leading to several stable and unstable coexisting solutions and potential wells with are closely linked to the systems symmetries. The effect of unavoidable initial imperfections is also clarified. The nonlinear dynamics and bifurcations of systems under harmonic forcing are studied using bifurcation diagrams, Poincaré maps and cross-sections of the basins of attraction. The effect of a static pre-load on global dynamics is also studied. Due to the bifurcation sequences emerging from each stable equilibrium configuration, a high number of coexisting solutions are observed, both periodic and aperiodic, leading to complex basins of attraction with broadening fractal regions. On the one hand, these scenarios can be valuable in several applications. On the other hand, multiple attractors and their fractal basins can lead to the loss of stability and dynamic integrity. Therefore, knowledge on the nonlinear static and dynamic behavior of multistable systems is primordial in any engineering application. As an application example, a system composed by two von Mises trusses is used in the process of energy harvesting through piezoelectric elements. The highly nonlinear behavior results in large amplitude oscillations for a wide range of excitation frequency, increasing its efficiency and applicability.

Due to size effects, the microtechnologies that are used to manufacture micro-sensors, allowed a drastic reduction of electrical power consumption. This feature contributed to the emergence of the concept of autonomous sensors, which have the ability to take the energy needed for their operation from the environment where they are located. Among the different energy sources, our choice was made on ambient mechanical vibrations. The electromechanical conversion is done within a transducer integrated with a micromechanical structure. In this work, we have designed and fabricated an electrostatic transducer based on silicon-glass technology, which required the development of a dedicated deep etching process. The device was tested experimentally and we have obtained a conversion of mechanical energy into electrical energy, corresponding to a power of 61 nW, with a device whose surface area is only 66 mm². This device is the first miniaturized silicon converter based on electrostatic transduction which does not use an electret

Multi-tier cellular networks have led to a paradigm shift in the deployment of base stations (BSs) where macrocell BSs are overlaid with smaller and lower power BSs such as microcells, picocells, and femtocells. Stochastic geometry has been proven to be an effective tool to capture such heterogeneity and uncertainties in deployment of cellular BSs. In stochastic geometry, random spatial models are used to model multi-tier cellular networks where the locations of BSs is each tier is assumed to be drawn from a point process with the appropriate spatial density. This thesis proposes stochastic geometry-based approaches to analyze, model, and optimize multi-tier cellular networks under several setups and technologies. First, I propose a novel location-aware cross-tier cooperation scheme that aim at improving the performance of users with low signal-to-interference-plus-noise ratio (SINR). Second, I study the performance of cognitive device-to-device (D2D) communication in multi-channel downlink-uplink cellular network with energy harvesting. For the coexistence between cellular and D2D transmissions, I propose a spectrum access policy for cellular BSs to avoid using D2D channels when possible. Third, I investigate the feasibility of energy harvesting from ambient RF interference in multi-tier uplink cellular networks. For this setup, I capture randomness in the network topology and the battery dynamics. Fourth, I extend multi-tier uplink cellular networks to consider the case when users do not necessarily associate with the nearest BS (i.e., flexible cell association). Finally, I compare between different cell association criteria including coupled and decoupled cell association for uplink and downlink transmissions in multi-tier full-duplex cellular networks. For all network setups, I use stochastic geometry to derive simple and closed-form expressions to evaluate the performance in terms of several metrics, e.g., outage probability, mean rate, transmission probability, success probability, and load per BS. I also highlight main tradeoffs in different networks and provide guidelines to optimize different performance metrics by carefully tuning fundamental network design parameters. / February 2017

L'amélioration de l'autonomie énergétique des systèmes communicants constitue aujourd'hui une des préoccupations majeures pour leur déploiement massif dans notre environnement. On souhaite rendre complètement autonome ces dispositifs électroniques (on pense entre autres aux capteurs et réseaux de capteurs) en s'affranchissant des sources d'énergie embarquées qui nécessitent des opérations de remplacement ou de recharge périodiques. Parmi les sources d'énergie disponibles qui peuvent être exploitées, on trouve les ondes électromagnétiques. Le dispositif qui permet de capter cette énergie et la convertir en puissance continue utile est dénommé Rectenna (Rectifying antenna) qui associe une antenne de captation à un circuit de rectification à base de diodes. Les rectennae ont fait l'objet d'un nombre important de communications dans la littérature ces dernières années avec pour fil conducteur, la recherche de performances optimales compte tenu de l'atténuation des ondes électromagnétiques et des faibles niveaux de champ récupérés. C'est dans ce contexte que s'est déroulé ce travail de thèse dont le financement a été assuré par un contrat ANR (REC-EM).Dans ce travail, on s'est attaché à développer, à concevoir et à caractériser expérimentalement des structures planaires qui présentent des propriétés intéressantes :- En terme de polarisations orthogonales, ceci de façon à s'affranchir de l'orientation arbitraire de l'onde incidente à la rectenna. Une rectenna à double polarisation circulaire à 2.45 GHz et à double accès sera réalisée pour, de plus, s'affranchir de la perte de 3 dB lorsque l'onde récupérée est à polarisation linéaire à orientation arbitraire.- En termes de résonances multiples, ceci pour augmenter le niveau de puissance récupérée par l'antenne et optimiser la puissance continue convertie. Une rectenna à double fréquence (1.8 et 2.45 GHz) et à accès unique sera conçue ainsi qu'une rectenna constituée d'un réseau de deux antennes double fréquence.- En terme de réduction de taille en s'affranchissant de l'utilisation du filtre HF entre l'antenne et le circuit de conversion ceci pour l'ensemble des structures rectennae développées dans ce travail. Dans tous les cas, il sera nécessaire de développer le circuit de rectification le plus adapté à la topologie de l'antenne de captation et évaluer la technique de recombinaison optimale coté DC pour s'affranchir au mieux des déséquilibres qui peuvent apparaître entre les voies d'accès de l'antenne. Pour contenir les dimensions de la structure globale, des circuits mono diode seront dimensionnés et réalisés pour chacune des structures. Enfin, on exploitera l'antenne à double polarisation circulaire double accès, dont on cherchera à diminuer les dimensions, pour alimenter un capteur de température à affichage LCD. Pour augmenter le niveau de tension nécessaire au fonctionnement du capteur, nous associerons entre la rectenna et le capteur un convertisseur DC-DC. Il s'agit, dans ce cas, d'un dispositif de gestion d'énergie adapté pour les faibles puissances. Deux convertisseurs seront employés dont celui développé par les laboratoires Ampère de l'Ecole Centrale de Lyon et SATIE à l'ENS Cachan. Ce convertisseur a fait l'objet d'une thèse également financée par l'ANR dans le cadre de ce contrat REC-EM / Improving energy autonomy of communication systems constitutes one of the major concerns for their massive deployment in our environment. We want to make these electronic devices (sensors and sensor networks) completely autonomous, avoiding the embedded energy sources that require replacement operations or periodic charging. Among the available energy sources that can be harvested, there are electromagnetic waves. The device that can capture this energy and convert it into useful DC power is called Rectenna (Rectifying antenna), combining antenna with diode-based rectifier. In recent few years, rectennas have reached a significant number of papers in the literature. The main challenge consists in improving performances in term of efficiency, in an attempt to overcome the electromagnetic wave attenuation and the low available field level. According to this context, this PhD work supported by the ANR project REC-EM has taken place. In this study, we have developed, designed and characterized planar structures that have interesting properties:- In term of orthogonal polarizations, so energy harvesting becomes feasable regardless the arbitrary orientation of the incident wave on the rectenna. A dual-circularly polarized rectenna at 2.45 GHz with dual-access will be set up to overcome the 3 dB power loss in the case of linearly-polarized incident wave with unknown orientation.- In term of multiple resonances, so the amount of total RF power collected by the antenna can be increased and consequently the converted DC power level can also be improved. A dual-frequency rectenna (1.8 and 2.45 GHz) with single access will be designed, as well as a rectenna based upon a dual-frequency antenna array.- In term of size compactness by avoiding the use of the HF filter between the antenna and the rectifier for all developed rectenna structures during this work. In all cases, it will be necessary to define the most suitable rectifier topology to each antenna and select, if it is appropriated, the optimum DC recombination technique to overcome the effects of RF power imbalance that may occur between the different antenna accesses. Besides, single-diode circuits will be designed and fulfilled for each structure. Finally, we will miniaturize the dual-circularly polarized dual-access antenna, and exploit it to power a LCD display temperature sensor. To enhance the DC voltage level required to activate the sensor, a DC-DC converter is inserted between the rectenna and the sensor. Such energy management device should be able to operate under low delivered DC power. Two converters will be used. The first one is developed by Ampere Lab at Ecole Centrale de Lyon and SATIE Lab at ENS Cachan. This converter was the subject of another dissertation also supported by the ANR under the REC-EM project

L’objectif du présent travail a été de concevoir et de fabriquer des dispositifs sur silicium pour convertir de l’énergie thermique en une énergie électrique en utilisant le changement de phase liquide-gaz dans le but de générer une variation subite de pression suivie d’une conversion d’énergie mécanique vers une énergie électrique à l’aide d’un piézoélectrique. La construction des dispositifs a dû rester simple, avec des matériaux courants et en respectant des limites dimensionnelles. Empreinte inférieure à un diamètre de 20 mm et une épaisseur en dessous des 2 mm.Les prototypes fabriqués sont composés de 3 plaques en silicium, contenant une chambre d’évaporation, une chambre de condensation et un canal réunissant les deux. Un transducteur piézoélectrique a été reporté sur la chambre de condensation et assure l’étanchéité ainsi que la génération d’énergie électrique.Le processus de conception inclut plusieurs étapes, dont la définition de la géométrie et du type de fluide de travail utilisé en tant qu’agent thermique. Le travail effectué a permis de sélectionner le type de piézoélectrique, sa taille ainsi que sa méthode d’intégration. Une étude a également été conduite pour déterminer la méthode optimale d’assemblage des plaques en silicium.La réalisation pratique des dispositifs a été orientée vers la sélection des meilleurs procédés technologiques pour la fabrication des structures. Toutes les expériences ont été conduites en salle blanche avec utilisation de l’oxydation humide, la photolithographie, la gravure KOH, ainsi que d’une technique d’assemblage des plaques silicium avec utilisation de la résine SU-8 comme couche intermédiaire. En plus, quelques outils spécifiques ont été conçus lors du présent travail, pour faciliter la fabrication des dispositifs, dont un système sous vide dédié à l’assemblage des plaques en silicium.Les dispositifs ont été testés afin d’établir leur mécanisme d’oscillation thermique ainsi que leurs propriétés électriques. L’influence tu taux de remplissage et de la température de surface chaude sur le signal en sortie ont également été étudiées. Le calcul de l’énergie générée a aussi été effectué. Dans la dernière partie de l’étude, des étapes d’optimisation pour les dispositifs développés dans le présent travail sont proposées. / The goal of the present work was to design and fabricate a fully silicon oscillating device that converts thermal energy into electricity, applying phenomena of liquid to gas phase-change and piezoelectricity. It should be characterized by simplicity of construction, small size, and ease of manufacture. The diameter should not exceed 2 cm, while the thickness should be within 2 mm.The device was composed of three Si wafers comprising evaporation and condensing chambers, and the channel connecting these two elements. A PZT-based transducer mounted on top of the structure was applied to ensure energy conversion.The design process included the establishment of the device geometry, the type of the working fluid enclosed inside the system, a type, size and assembly technique of a piezoelectric element, as well as a bonding method of several silicon elements of the device.The practical realization of the designed prototypes was aimed at selecting the most suitable technological processes for structure fabrication. All the experiments had been performed in a clean room environment and employed wet oxidation, photolithography, a well-known, easily available wet chemical etching in KOH solution, and a silicon bonding technique with the use of SU-8 photoresist as an intermediate layer. Additionally, during the practical work a few tools have been designed and developed to enhance the device fabrication, amongst which a vacuum pump dedicated to bond the three silicon wafers as structural elements of the prototypesThe fabricated prototypes were tested in terms of oscillation mechanism and electrical properties. The influence of the filling ratio and the hot temperature value on the generated signal was established. Additionally, the power range of the prototypes has been evaluated. In the last part of the study, optimization steps for the devices developed in the present work have been proposed.

Transdutores baseados em cascas piezocompósitas têm uma vasta aplicação no campo de estruturas inteligentes, principalmente como atuadores, sensores e coletores de energia. Essas estruturas piezocompósitas são geralmente compostas por dois ou mais tipos de materiais, como por exemplo materiais piezelétricos, ortotrópicos elásticos (possuem fibras de reforçamento) e isotrópicos (materiais homogêneos). Vários fatores devem ser considerados no projeto de transdutores baseados em cascas piezocompósitas, como o tamanho, a forma, a localização e a polarização do material piezelétrico, bem como a orientação das fibras do material ortotrópico. O projeto desses transdutores é complexo e trabalhos anteriores envolvendo esses tipos de materiais sugerem utilizar Método de Otimização Topológica (MOT) para aprimorar o desempenho dos transdutores distribuindo o material piezelétrico sobre substratos fixos de materiais isotrópicos e ortotrópicos, ou otimizar a orientação das fibras dos materiais ortotrópicos com material piezelétrico com tamanho, forma e localização previamente estabelecidos. Assim, nesta tese, propõe-se o desenvolvimento de uma metodologia baseada no MOT para projetar transdutores piezocompósitos de casca considerando, simultaneamente, a otimização da distribuição e do sentido de polarização do material piezelétrico, e também a otimização da orientação das fibras de materiais ortotrópicos, que é livre para assumir valores diferentes ao longo da mesma camada compósita. Utilizando essa metodologia, são obtidos resultados numéricos para atuadores e sensores em regime estático e para coletores de energia com circuito elétrico acoplado, em regime dinâmico amortecido. Para os casos dos sensores e dos coletores de energia, também são consideradas as tensões mecânicas na estrutura, as quais devem obedecer os critérios de von Mises (para materiais isotrópicos) e de Tsai-Wu (para materiais ortotrópicos) para que não haja falhas na estrutura, que está sujeita a esforços mecânicos. / Transducers based on laminated piezocomposite shell structures have a wide application in the field of smart structures, especially as actuators, sensors and energy harvesting devices. These piezocomposite structures are generally composed by two or more kinds of materials, such as piezoelectric, isotropic, and elastic orthotropic (fiber reinforcement) materials. Several factors must be considered in the design of piezocomposite transducers, such as size, shape, location and polarization of the piezoelectric material and the fiber orientation of the orthotropic material. The design of these transducers is complex and previous studies involving these types of materials suggest using \"Topology Optimization Method\" (TOM) to enhance the performance of piezoelectric transducers by distributing piezoelectric material over fixed isotropic and orthotropic substrate or to optimize the fiber orientation of orthotropic materials with piezoelectric patches previously established. Thus, this thesis proposes the development of a methodology based on the TOM to design laminated piezocomposite shell transducers by considering simultaneously the optimization of distribution and the polarization direction of the piezoelectric material, and also the optimization of the fiber orientation orthotropic material, which is free to assume different values along the same composite layer. By using this methodology, numerical results are obtained for actuators and sensors under static response, and energy harvesting devices with an electrical circuit coupled, in dynamic damped analysis. In the case of sensors and energy harvesting devices, which are subjected to mechanical loads, the mechanical stresses in the structure are also considered, which must satisfy two stress criteria to prevent failure: von Mises for isotropic materials and Tsai-Wu for orthotropic materials.

A natureza vibratória, oriunda da transferência energética, manifesta-se em todos os sistemas e estruturas. Na engenharia, essa transferência energética se revela como um fenômeno vibratório indesejável ou desejável. Em sistemas mecânicos, o controle dinâmico para mitigação de vibrações indesejáveis se realiza através de diversas técnicas e configurações, entre os mais usuais, o Amortecedor de Massa Sintonizável (AMS). No entanto, sabe-se que seu desempenho é suscetível a alterações nas frequências de operação e na natureza das excitações. Em sistemas elétricos, as vibrações do ambiente podem ser desejáveis e convertidas em energia elétrica útil para a realimentação de rede de sensores sem fio e computação pervasiva. A fim de combinar estes fenômenos e reduzir custos de operação, é necessário projetar dispositivos sintonizáveis robustos capazes de operar eficientemente em uma banda larga de frequências. Portanto, este trabalho visa projetar e analisar experimentalmente um atenuador de vibrações eletromagnético sintonizável (semi-ativo) com captação energética (AEMSCE) através da introdução deliberada de não linearidades. O AEMSCE consiste em um sistema massa-mola-amortecedor não linear com um ímã oscilante central orientado sob forças repulsivas magnéticas e uma bobina instalada, sendo capaz de dissipar as vibrações da estrutura e convertê-las em energia elétrica útil. Os recursos e parâmetros do AEMSCE são apresentados e identificados. O fator de transdução eletromagnético que acopla o sistema mecânico ao elétrico é quantificado. Mostra-se que a variação da distância entre ímãs promove ao sistema ressonância ajustável e que a força de restauração magnética resultante apresenta uma faixa de operação linear. No trabalho, verifica-se que o campo de máxima captação energética está contido na faixa de operação linear confirmando a relevância deste campo linear. O comportamento do sistema é analisado considerando as influências da força restauradora magnética, das forças amortecidas e da força de atrito. A partir dessas análises e das aproximações realizadas, apresenta-se estratégias de controle passivas e técnicas de otimização para mitigação, cuja resultante é um campo de atenuação ótimo, assim como desenvolve-se métodos de otimalidade para maximizar a conversão energética do AEMSCE, cuja resultante é um amortecimento elétrico ótimo ou um amortecimento admissível ótimo (deslocamento máximo). Métodos analíticos e simulações numéricas são desenvolvidos em todo o trabalho com diferentes configurações para analisar a robustez e eficiência do dispositivo, através do comportamento dinâmico vibratório à resposta transiente e estacionária induzido por excitação de base harmônica. De maneira geral, os resultados mostram que os parâmetros de sintonia e amortecimento do AEMSCE podem ser combinados e ajustados para ampliar o controle de vibrações da estrutura e maximizar a captação energética, principalmente na ressonância. Verifica-se que existe uma relação de importância da tensão induzida e do amortecimento elétrico, através da variação da resistência de carga no resistor, com a atenuação e captação energética. Por fim, este trabalho buscou apresentar os melhores métodos e resultados de parâmetros de amortecimento a fim de obter informações como guia de projeto para otimizar os dispositivos futuros e para a proposição de incorporar um controle semiativo ao AEMSCE. Como forma de melhorar o desempenho em aplicações futuras, é possível combinar as propriedades ótimas resultantes e ajustá-las através de estratégias de controle semiativa, explorando a dinâmica linear e não linear do sistema. / Vibratory nature, derived from the energy transfer, manifests itself in all systems and structures. In engineering, this energy transfer is revealed as an undesirable or desirable vibrational phenomenon. In mechanical systems, the dynamic control to mitigate undesirable vibrations is achieved through several techniques and configurations, among the most usual, the Tunable Mass Damper (TMD). However, it is known that their performance is susceptible to changes in the operating frequencies and the nature of the excitations. In electrical systems, ambient vibrations may be desirable and converted into useful electrical energy for the feedback of wireless sensors network and pervasive computing. In order to combine these phenomena and reduce operating costs, it is necessary to design robust tunable devices capable of operating efficiently over a wide frequency band. Therefore, this work aims to design and experimentally analyze a tunable electromagnetic vibrations absorver (semi-active) with energy harvesting (TEMAEH) through the deliberated introduction of non-linearities. TEMAEH consists of a non-linear mass-spring-damper system with a central oscillating magnet oriented under magnetic repulsive forces and a coil installed, being able to dissipate vibrations of the structure and convert them into useful electrical energy. The TEMAEH features and parameters are presented and identified. Electromagnetic transduction factor that couples the mechanical to electrical system is quantified. It is shown that the variation of the distance between magnets provides adjustable resonance to the system and that the resulting magnetic restoring force has a linear operating range. In the work, it is verified that the field of maximum energy harvesting is contained in the linear operating range confirming the relevance of this linear field. The behavior of the system is analyzed considering the influences of magnetic restoring force, damped forces and frictional force. From these analyzes and the approximations performed, passive control strategies and optimization techniques for mitigation are presented, resulting in an optimum attenuation field, as well as optimization methods to maximize the energy conversion of the TEMAEH, resulting in an optimum electric damping or optimum permissible damping (maximum displacement). Analytical methods and numerical simulations are developed throughout the work with different configurations to analyze the robustness and efficiency of the device through the dynamic behavior of vibration to the transient and stationary response induced by harmonic based excitation. In general, the results show that the tuning and damping parameters of the TEMAEH can be combined and adjusted to increase the vibration control of the structure and to maximize energy harvesting, especially in resonance. It is verified that there is a relation of importance of the induced voltage and the electrical damping, through the variation of the load resistance in the resistor, with the attenuation and power generation. Finally, this work sought to present the best methods and results of damping parameters in order to obtain information as a project guide to optimize future devices and for the proposition to incorporate a semiative control to TEMAEH. As a way to improve performance in future applications, it is possible to combine the resulting optimal properties and adjust them through semiative control strategies, exploring the linear and non-linear dynamics of the system.

The design and implementation of self-powered, low power implant microcontroller, with wireless data transmitter system that captures data as subcutaneous bio-sensing platform has been achieved with glucose fuel cell (GFC) energy harvesting power solution. Data transfer is unidirectional, implant to reader and is initiated by a single transmission from the external reader. The implant's memory contents are transmitted as a stream of wireless pulses to the reader. This work explored two different approaches on current technologies used for designing self-powered bio medical devices (BMDs) and active implantable medical devices (IMDs), their processing, sampling data, transmission of data and energy hasting powering techniques with a view to identifying state-of-the art technologies and methods to improve the long-term powering and recharging of IMDs via a highly safe, efficient and convenient way. The designed low power implant microcontroller, with wireless data transmitter system combines glucose energy harvesting technique by using materials with efficient catalyst capabilities based on platinum nanoparticles supported on Vulcan carbon cloth (PtVCC) as a cathode electrode for GFC configuration, while plain Platinum (Pt) mesh/sheet acted as anode. The PtVCC and Pt electro-reaction, catalytic activities and stability resulted in a design of a direct GFC with high output voltage and current, >0.4V and >300μA respectively per cell, and increased this voltage to value >4V, to power the implant system, by using a voltage booster; direct current to direct current (DC-DC) converter circuit, and a rechargeable battery. The innovative self-powered bio-sensing platform integrating GFC design, meets the self-powered IMDs expectations in terms of simplified fabrication and materials that allows one-compartment design that can directly be placed on the surface of medical implant to provide sufficient output power boosted by DC-DC converter to produced higher output voltage ten times greater than the input value, enough to power most efficient electronic devices. This research therefore proposes the practicability and potential of designing and implementing a wireless bio sensor system powered by an energy harvesting solution, based on GFC to produce a proof-of-concept design system and integration, including power management and data communication (sampling and transmission) platform suitable for self-low-powered periodically-activated IMD.