Smart structure control systems commonly use piezoceramic sensors or accelerometers as vibration measurement devices. These measurement devices often produce noisy and/or low-precision signals, which makes it difficult to measure small-amplitude vibrations. Laser interferometry devices pose as an alternative high-precision position measurement method, capable of nanometer-scale resolution. The aim of this research is to utilize a model-based design approach to develop and implement a real-time Linear Quadratic Gaussian (LQG) regulator for a piezoelectric actuated smart structure using a high-precision laser interferometry measurement system to suppress the excitation of vibratory modes. The analytical model of the smart structure is derived using the extended Hamilton Principle and Euler-Bernoulli beam theory, and the equations of motion for the system are constructed using the assumed-modes method. The analytical model is organized in state-space form, in which the effects of a low-pass filter and sampling of the digital control system are also accounted for. The analytical model is subsequently validated against a finite-element model in Abaqus, a lumped parameter model in Simscape Multibody, and experimental modal analysis using the physical system. A discrete-time proportional-derivative (PD) controller is designed in a heuristic fashion to serve as a baseline performance criterion for the LQG regulator. The Kalman Filter observer and Linear Quadratic Regulator (LQR) components of the LQG regulator are also derived from the state-space model. It is found that the behavior of the analytical model closely matches that of the physical system, and the performance of the LQG regulator exceeds that of the PD controller. The LQG regulator demonstrated quality estimation of the state variables of the system and further constitutes an exceptional closed-loop control system for active vibration control and disturbance rejection of the smart structure.

Denna rapport sammanfattar resultat av ett examensarbete på en högskoleingenjörsutbildningsom utfördes av två studenter på Malmö högskola.Arbetets syfte var att genomföra en mängd olika experiment med accelerometer, barometeroch GPS i en modern smarttelefon. Ett antal scenarier för en tänkbar sensoranvändning i applikationerformulerades för att vägleda olika experiment. Experimentdata dokumenterades noggrantoch analyserades med avsikten att skapa en databank med information för framtida studier.Analys av data inkluderar höjdbestämning i naturen och i byggnader med hjälp av barometersensor,geografisk position med hjälp av GPS, hastighet och acceleration under en hissfärdmed hjälp av accelerometer.Rapporten innehåller en omfattande litteraturstudie om användning av sensorer vid inomhuspositionering.Från analys av mätdata, kom vi fram till slutsatsen att är möjligt att beräkna höjdenfrån barometerdata med bra noggrannhet under optimala omständigheter. GPS höjdenfrån mätningarna har stor felmarginal jämfört med den verkliga höjden samt när den jämförsmed den beräknade höjden från barometern.Genom att utföra en numerisk integration på accelerometer-data kom vi fram till att det är möjligtatt beräkna ungefär hur långt man har färdats med en hiss, dock att vissa detaljer måste tasi beaktning. / This report summarizes the results of a degree Bachelor of engineering in Computer Scienceconducted by two students at Malmo University.Work aim was to conduct a variety of experiments with accelerometer, barometer and GPS in amodern smartphone. A number of scenarios for a possible sensor use in applications formulatedto guided experiments. Data is carefully documented and analyzed, with the intention tocreate a database of information for future studies. Analysis of the data includes the altitudedetermination in nature and in buildings using barometric sensor, geographic location usingGPS, speed and acceleration during an elevator journey with the help of accelerometer.The report contains a comprehensive literature review on the use of sensors for indoorpositioning.From our analysis of the measurement data, we conclude that it is possible to calculate thealtitude from barometric- information but good accuracy if there are optimum circumstances.GPS altitude from our measurements show faulty height by a large margin compared with theactual height and when it is compared with the calculated height of the barometer the barometricheight is closer to the actual height.By performing a numerical integration of the accelerometer data, the results show that it ispossible to calculate approximately how far you have traveled in meters in an elevator, howeverthere are some things that must be taken into consideration.

<p>Microbiological contamination from bacteria such as <em>Escherichia coli</em> and Salmonella is one of the main reasons for waterborne illness. Real time and accurate monitoring of water is needed in order to alleviate this human health concern. Performing multiple and parallel analysis of biomarkers such as DNA and mRNA that targets different regions of pathogen functionality provides a complete picture of its presence and viability in the shortest possible time. These biomarkers are present inside the cell and need to be extracted for analysis and detection. Hence, lysis of these pathogenic bacteria is an important part in the sample preparation for rapid detection. In addition, collecting a small amount of bacteria present in a large volume of sample and concentrating them before lysing is important as it facilitates the downstream assay. Various techniques, categorized as mechanical, chemical, thermal and electrical, have been used for lysing cells. In the electrical method, cells are lysed by exposure to an external electric field. The advantage of this method, in contrast to other methods, is that it allows lysis without the introduction of any chemical and biological reagents and permits rapid recovery of intercellular organelles. Despite the advantages, issues such as high voltage requirement, bubble generation and Joule heating are associated with the electrical method.</p> <p>To alleviate the issues associated with electrical lysis, a new design and associated fabrication process for a microfluidic cell lysis device is described in this thesis. The device consists of a nanoporous polycarbonate (PCTE) membrane sandwiched between two PDMS microchannels with electrodes embedded at the reservoirs of the microchannels. Microcontact printing is used to attach this PCTE membrane with PDMS.</p> <p>By using this PCTE membrane, it was possible to intensify the electric field at the interface of two channels while maintaining it low in the other sections of the device. Furthermore, the device also allowed electrophoretic trapping of cells before lysis at a lower applied potential. For instance, it could trap bacteria such as <em>E. coli</em> from a continuous flow into the intersection between two channels for lower electric field (308 V/cm) and lyse the cell when electric field was increased more than 1000 V/cm into that section.</p> <p>Application of lower DC voltage with pressure driven flow alleviated adverse effect from Joule heating. Moreover, gas evolution and bubble generation was not observed during the operation of this device.</p> <p>Accumulation and lysis of bacteria were studied under a fluorescence microscope and quantified by using intensity measurement. To observe the accumulation and lysis, LIVE/DEAD BacLight Bacterial Viability Kit consisting of two separate components of SYTO 9 and propidium iodide (PI) into the cell suspension in addition to GFP expressed <em>E. coli</em> were used. Finally, plate counting was done to determine the efficiency of the device and it was observed that the device could lyse 90% of bacteria for an operation voltage of 300V within 3 min.</p> <p>In conclusion, a robust, reliable and flexible microfluidic cell lysis device was proposed and analyzed which is useful for sample pretreatment in a Micro Total Analysis System.</p> / Master of Applied Science (MASc)

Fatigue testing of stretch sensors often focuses on high amplitude, low-cycle fatigue (LCF) behavior; however, when used for orthopaedic, athletic, or ergonomic assessments, stretch sensors are subjected to low amplitude, high-cycle fatigue (HCF) conditions. As an added layer of complexity, the fatigue testing of stretch sensors is not only focused on the life of the material comprising the sensor, but also on the reliability of the signal produced during the extension and relaxation of the sensor. Research into the development of a smart sock that can be used to measure the range of motion (ROM) of the ankle joint during athletic practices and competitions using stretch sensors is ongoing at Mississippi State University. The current smart sock prototype utilizes StretchSense™ StretchFABRIC capacitive dielectric elastomer sensors. These sensors are no longer manufactured, and FlexSense stretch sensors are being investigated as a potential replacement. To assess the reliability of the signal of the StretchFABRIC sensors currently used in the prototype, two sensors were subjected to 25,000 cycles of fatigue, under with simultaneous capture of the capacitance. The capacitances of the fatigued sensors were then compared to the capacitance of an unfatigued StretchFABRIC sensor during participant trials. Participants completed four static movements and six dynamic gait trials using either the fatigued or unfatigued sensor. Following completion of the initial static and dynamic movements, the movements were repeated using the opposite sensor. Comparison of the fatigued sensor to the unfatigued sensor revealed an upward drift in the capacitance of the fatigued sensor for all trials. Two FlexSense sensors were then subjected to either 450,000 or 250,000 cycles of fatigue with simultaneous capture of the signal from the sensor. To assess the signal, the peak capacitance recorded during the fatigue test was compared to the peak stretch percentage produced by the sensor. The peak displacement remained tight about the mean, while the peak stretch percentage exhibited a high level of scatter. From a materials standpoint, the sensors conformed to the Rabinowitz-Beardmore model of polymer fatigue where an initial monotonic overload of the material is followed by a transition to cyclic stability of the material.

Dynamic testing provides valuable insight into the behavior of materials undergoing fast deformation. During Split-Hopkinson Pressure Bar testing, stress waves are measured using strain gauges as voltage variations that are usually very small. Therefore, an amplifier is required to amplify the data and analyze it. One of the few available amplifiers designed for this purpose is provided by Vishay Micro-Measurements which limits the user’s options when it comes to research or industry. Among the challenges of implementing the Hopkinson technology in the industry are the size and cost of the amplifier. In this work, we propose a novel design of a signal conditioning amplifier that provides the following functionalities: voltage excitation for strain gauges, wide gain range (1-1000), signal balancing, shunting, and filtering. The main objective is to make a smaller and cheaper amplifier that provides equivalent or better performance allowing larger application of the Hopkinson technology in the industry.

The development of a numeric simulation for predicting the performance of an Ocean Current Energy Conversion System is presented in this thesis along with a control system development using a PID controller for the achievement of specified rotational velocity set-points. In the beginning, this numeric model is implemented in MATLAB/Simulink® and it is used to predict the performance of a three phase squirrel single-cage type induction motor/generator in two different cases. The first case is a small 3 meter rotor diameter, 20 kW ocean current turbine with fixed pitch blades, and the second case a 20 meter, 720 kW ocean current turbine with variable pitch blades. Furthermore, the second case is also used for the development of a Voltage Source Variable Frequency Drive for the induction motor/generator. Comparison among the Variable Frequency Drive and a simplified model is applied. Finally, the simulation is also used to estimate the average electric power generation from the 720 kW Ocean Current Energy Conversion System which consists of an induction generator and an ocean current turbine connected with a shaft which modeled as a mechanical vibration system.

Cette thèse explore la reconnaissance de gestes à partir de capteurs inertiels pour Smartphone. Ces gestes consistent en la réalisation d'un tracé dans l'espace présentant une valeur sémantique, avec l'appareil en main. Notre étude porte en particulier sur l'apprentissage de métrique entre signatures gestuelles grâce à l'architecture "Siamoise" (réseau de neurones siamois, SNN), qui a pour but de modéliser les relations sémantiques entre classes afin d'extraire des caractéristiques discriminantes. Cette architecture est appliquée au perceptron multicouche (MultiLayer Perceptron). Les stratégies classiques de formation d'ensembles d'apprentissage sont essentiellement basées sur des paires similaires et dissimilaires, ou des triplets formés d'une référence et de deux échantillons respectivement similaires et dissimilaires à cette référence. Ainsi, nous proposons une généralisation de ces approches dans un cadre de classification, où chaque ensemble d'apprentissage est composé d’une référence, un exemple positif, et un exemple négatif pour chaque classe dissimilaire. Par ailleurs, nous appliquons une régularisation sur les sorties du réseau au cours de l'apprentissage afin de limiter les variations de la norme moyenne des vecteurs caractéristiques obtenus. Enfin, nous proposons une redéfinition du problème angulaire par une adaptation de la notion de « sinus polaire », aboutissant à une analyse en composantes indépendantes non-linéaire supervisée. A l'aide de deux bases de données inertielles, la base MHAD (Multimodal Human Activity Dataset) ainsi que la base Orange, composée de gestes symboliques inertiels réalisés avec un Smartphone, les performances de chaque contribution sont caractérisées. Ainsi, des protocoles modélisant un monde ouvert, qui comprend des gestes inconnus par le système, mettent en évidence les meilleures capacités de détection et rejet de nouveauté du SNN. En résumé, le SNN proposé permet de réaliser un apprentissage supervisé de métrique de similarité non-linéaire, qui extrait des vecteurs caractéristiques discriminants, améliorant conjointement la classification et le rejet de gestes inertiels. / As consumer devices become more and more ubiquitous, new interaction solutions are required. In this thesis, we explore inertial-based gesture recognition on Smartphones, where gestures holding a semantic value are drawn in the air with the device in hand. In our research, speed and delay constraints required by an application are critical, leading us to the choice of neural-based models. Thus, our work focuses on metric learning between gesture sample signatures using the "Siamese" architecture (Siamese Neural Network, SNN), which aims at modelling semantic relations between classes to extract discriminative features, applied to the MultiLayer Perceptron. Contrary to some popular versions of this algorithm, we opt for a strategy that does not require additional parameter fine tuning, namely a set threshold on dissimilar outputs, during training. Indeed, after a preprocessing step where the data is filtered and normalised spatially and temporally, the SNN is trained from sets of samples, composed of similar and dissimilar examples, to compute a higher-level representation of the gesture, where features are collinear for similar gestures, and orthogonal for dissimilar ones. While the original model already works for classification, multiple mathematical problems which can impair its learning capabilities are identified. Consequently, as opposed to the classical similar or dissimilar pair; or reference, similar and dissimilar sample triplet input set selection strategies, we propose to include samples from every available dissimilar classes, resulting in a better structuring of the output space. Moreover, we apply a regularisation on the outputs to better determine the objective function. Furthermore, the notion of polar sine enables a redefinition of the angular problem by maximising a normalised volume induced by the outputs of the reference and dissimilar samples, which effectively results in a Supervised Non-Linear Independent Component Analysis. Finally, we assess the unexplored potential of the Siamese network and its higher-level representation for novelty and error detection and rejection. With the help of two real-world inertial datasets, the Multimodal Human Activity Dataset as well as the Orange Dataset, specifically gathered for the Smartphone inertial symbolic gesture interaction paradigm, we characterise the performance of each contribution, and prove the higher novelty detection and rejection rate of our model, with protocols aiming at modelling unknown gestures and open world configurations. To summarise, the proposed SNN allows for supervised non-linear similarity metric learning, which extracts discriminative features, improving both inertial gesture classification and rejection.

Monitoring the mechanical integrity of critical structures is extremely important, as mechanical defects can potentially have adverse impacts on their safe operability throughout their service life. Structural defects can be detected by using active structural health monitoring (SHM) approaches, in which a given structure is excited with harmonic mechanical waves generated by actuators. The response of the structure is then collected using sensor(s) and is analyzed for possible defects, with various active SHM approaches available for analyzing the response of a structure to single- or multi-frequency harmonic excitations. In order to identify the appropriate excitation frequency, however, the majority of such methods require a priori knowledge of the characteristics of the defects under consideration. This makes the whole enterprise of detecting structural defects logically circular, as there is usually limited a priori information about the characteristics and the locations of defects that are yet to be detected. Furthermore, the majority of SHM techniques rely on sensors for response collection, with the very same sensors also prone to structural damage. The Surface Response to Excitation (SuRE) method is a broadband frequency method that has high sensitivity to different types of defects, but it requires a baseline. In this study, initially, theoretical justification was provided for the validity of the SuRE method and it was implemented for detection of internal and external defects in pipes. Then, the Comprehensive Heterodyne Effect Based Inspection (CHEBI) method was developed based on the SuRE method to eliminate the need for any baseline. Unlike traditional approaches, the CHEBI method requires no a priori knowledge of defect characteristics for the selection of the excitation frequency. In addition, the proposed heterodyne effect-based approach constitutes the very first sensor-less smart monitoring technique, in which the emergence of mechanical defect(s) triggers an audible alarm in the structure with the defect. Finally, a novel compact phased array (CPA) method was developed for locating defects using only three transducers. The CPA approach provides an image of most probable defected areas in the structure in three steps. The techniques developed in this study were used to detect and/or locate different types of mechanical damages in structures with various geometries.

Ce manuscrit de thèse propose l'optimisation de l'ensemble de la chaîne de reproduction sonore dans un système embarqué. Le premier axe de recherche introduit les notions générales concernant les systèmes audio embarqués nécessaires à la bonne compréhension du contexte de la recherche. Le principe de conversion de l'ensemble de la chaine est présenté afin de comprendre les différentes étapes qui composent un système audio. Un état de l'art présente les différents types de haut-parleurs ainsi que l'électronique associé les plus couramment utilisées dans les systèmes embarqués. Le second axe de recherche propose une approche globale : une modélisation électrique du haut-parleur (tenant compte d'un nombre optimal de paramètres) permet à un électronicien de mieux appréhender les phénomènes non-linéaires du haut-parleur qui dégradent majoritairement la qualité audio. Il en résulte un modèle viable qui permet d'évaluer la non-linéarité intrinsèque du haut-parleur et d'en connaitre sa cause. Les résultats des simulations montrent que le taux de distorsion harmonique intrinsèque au haut-parleur est supérieur à celui généré par un amplificateur. Le troisième axe de recherche met en avant l'impact du contrôle du transducteur. L'objectif étant de savoir s'il existe une différence, du point de vue de la qualité audio, entre la commande asservie par une tension ou par un courant, d'un micro-haut-parleur électrodynamique. Pour ce type de transducteur et à ce niveau de la modélisation, le contrôle en tension est équivalent à contrôler directement le haut-parleur en courant. Néanmoins, une solution alternative (ne dégradant pas davantage la qualité audio du signal) pourrait être de contrôler le micro-haut-parleur en courant. Le quatrième axe de recherche propose d'adapter les spécifications des amplificateurs audio aux performances des micro-haut-parleurs. Une étude globale (énergétique) démontre qu'un des facteurs clés pour améliorer l'efficacité énergétique du côté de l'amplificateur audio est la minimalisation de la consommation statique en courant, en maximalisant le rendement à puissance nominale. Pour les autres spécifications, l'approche globale se base sur l'étude de l'impact de la spécification d'un amplificateur sur la partie acoustique. Cela nous a par exemple permis de réduire la contrainte en bruit de 300%. Le dernier axe de recherche s'articule autour d'un nouveau type de transducteur : un micro-haut-parleur en technologie MEMS. La caractérisation électroacoustique présente l'amélioration en terme de qualité audio (moins de 0,016% de taux de distorsion harmonique) et de plage de fréquence utile allant de 200 Hz à 20 kHz le tout pour un niveau sonore moyen de 80dB (10cm). La combinaison de tous les efforts présente un réel saut technologique. Enfin, la démarche globale d'optimisation de la partie électrique a été appliquée aux performances du MEMS dans la dernière section, ce qui a notamment permis de réduire la contrainte en bruit de 500%. / This thesis proposes the optimization of the whole sound reproduction chain in an embedded system. The first research axis is introduces the general concepts concerning audio systems necessary for the good understanding of the context of research. The principle of conversion of the entire chain is presented to understand the stages that make up a sound system. A state of the art presents various loudspeakers and the associated electronics most commonly used in embedded systems. The second research axis proposes a global approach: electric modeling of loudspeaker (taking into account an optimum number of parameters) that allows electronics engineer a better understanding of the nonlinear phenomena that degrade mostly audio quality in loudspeakers. It results in a sustainable model which evaluates the intrinsic non-linearity in loudspeakers and to know its cause. The simulation results show that the total harmonic distortion intrinsic to the loudspeaker is higher than that the distortion generated by an amplifier. The third research axis highlights the impact of the control of the transducer. The aim is to find out if there is a difference, in terms of audio quality, between the feedback control by voltage or current, for an electrodynamic micro-speaker. For this type of transducer and at this level of modeling, voltage control is equivalent to directly control the current of the micro-speaker. However, an alternative solution (not further degrading the signal audio quality) could be to control directly the micro-speaker by a current. The fourth research axis proposes to adapt the audio amplifiers specification to the performance of the micro-speakers. A comprehensive study of an energy point of view shows that a key factor for improving the energy efficiency of the audio amplifier is the minimization of the static power consumption and the maximization of the performance at nominal power. For other specifications, the global approach is based on the study of the impact of the specification of an amplifier on the sound pressure level. This has allowed, for example to reduce the stress in output noise voltage by a ratio of 300 %. The last research axis focuses on a new type of transducer: a micro-speaker in MEMS technology. Electroacoustic characterization shows the improvement: in terms of audio quality (less than 0.016 % total harmonic distortion) and the useful frequency range from 200 Hz to 20 kHz, the whole for an average sound level of 80 dB (10 cm). The combination of all the efforts presents a real technological leap. Finally, the overall process of optimization of the electrical part has been applied to the performance of MEMS in this last section, which has resulted, for example, in a reduction in the noise constraint of 500 %.

L'isolation thermique est essentielle dans de nombreux types de MEMS (micro-systèmes électro-mécaniques). Selon le type de dispositif, l'isolation permet de réduire la consommation d'énergie, diminuer le temps de réponse, ou augmenter sa sensibilité. Les matériaux d'isolation thermique actuellement disponibles sont difficiles à intégrer en couche épaisse dans des dispositifs en silicium. À cause de cela, l'approche la plus utilisée pour l'isolation est d'intégrer les zones à isoler sur des membranes minces (~ 1 µm). Cela assure une bonne isolation, mais est restrictif pour la conception du dispositif et la fragilité des membranes complique la fabrication et l'utilisation de celui-ci. Le silicium poreux est facile à intégrer puisqu'il est fabriqué par gravure électrochimique de substrats de Si cristallin. On peut aisément fabriquer des couches épaisses (100 µm) et sa conductivité thermique est 2-3 ordres de grandeur plus faible que celle du Si massif. Par contre sa porosité cause des problèmes : mauvaise résistance chimique, structure instable au-delà de 400°C, et tenue mécanique réduite. La facilité d'intégration des semiconducteurs poreux est un atout majeur, et nous visons donc de réduire les désavantages de ces matériaux afin de favoriser leur intégration dans des dispositifs en silicium. La première approche qui a été développée consiste à amorphiser le Si poreux en l'irradiant avec des ions à haute énergie (uranium, 110 MeV). Nous avons montré que l'amorphisation, même partielle, du Si poreux entraîne une diminution de sa conductivité thermique, sans endommager sa structure poreuse. On peut atteindre ainsi une réduction de conductivité thermique jusqu’à un facteur de trois. La seconde approche est de développer un nouveau matériau. Le SiC poreux a été choisi, puisque le SiC massif a des propriétés physiques exceptionnelles et supérieures à celles du silicium. Nous avons mené une étude systématique de la porosification du SiC en fonction de la concentration en HF et le courant, ce qui nous a permis de fabriquer des couches poreuses uniformes d’une épaisseur d’environ 100 µm. Nous avons implémenté un banc de mesure de la conductivité thermique par la méthode « 3 oméga » et l'avons utilisé pour mesurer la conductivité thermique du SiC poreux. Nos résultats montrent que la conductivité thermique du SiC poreux est environ deux ordres de grandeur plus faible que celle du SiC massif. Nous avons aussi montré que le SiC poreux est résistant à tous les produits chimiques typiquement utilisés en microfabrication et est stable jusqu'à au moins 1000°C. / Thermal insulation is essential in several types of MEMS (Micro electro mechanical systems). Depending on the device, insulation can reduce the device’s power consumption, decrease its response time, or increase its sensitivity. Existing thermal insulation materials are difficult to integrate as thick layers in silicon-based devices. Because of this, the most commonly used approach is to integrate the areas requiring insulation on thin membranes. This provides effective insulation, but restricts the design of the device and the membrane’s fragility makes the device’s fabrication and use more complicated. Poreux silicon is easy to integrate as it is made by electrochemical etching of crystalline silicon substrates. 100 µm thick layers can easily be fabricated and its thermal conductivity is 2-3 orders of magnitude lower than that of bulk silicon. However, its porosity causes other problems : low chemical resistance, its structure is unstable above 400°C, and reduced mechanical stability. The ease of integration of porous semiconductors remains a major advantage, so we aim to reduce the disadvantages of these materials in order to help their integration in microfabricated devices. The first approach we developed was to amorphise porous Si by irradiating it with heavy ions. We have shown that amorphisation of porous Si, even partial, causes a reduction of its thermal conductivity without damaging its porous structure. In this way a reduction in thermal conductivity by up to a factor of three can be achieved. The second approach was to develop a new material. Porous SiC was chosen, as bulk SiC has exceptional physical properties which are superior to those of silicon. We carried out a systematic study of the porosification process of SiC versus HF concentration and current, which enabled us to make thick (100 µm) and uniform layers. We have implemented a system for measuring thermal conductivity using the “3 omega” technique and used it to measure the thermal conductivity of porous SiC. Our results show that the thermal conductivity of porous SiC is about two orders of magnitude lower than that of bulk SiC. We have also shown that porous SiC is resistant to all chemical commonly used in microfabrication, and is stable up to at least 1000°C.