Today in the scientific and technological world, physical and artificial processes are often described by mathematical models which can be used for simulation, optimization or control. As the mathematical models get more detailed and different coupling effects are required to include, usually the dimension of these models become very large. Such large-scale systems lead to large memory requirements and computational complexity. To handle these large models efficiently in simulation, control or optimization model order reduction (MOR) is essential. The fundamental idea of model order reduction is to approximate a large-scale model by a reduced model of lower state space dimension that has the same (to the largest possible extent) input-output behavior as the original system. Recently, the system-theoretic method Balanced Truncation (BT) which was believed to be applicable only to moderately sized problems, has been adapted to really large-scale problems. Moreover, it also has been extended to so-called descriptor systems, i.e., systems whose dynamics obey differential-algebraic equations. In this thesis, a BT algorithm is developed for MOR of index-1 descriptor systems based on several papers from the literature. It is then applied to the setting of a piezo-mechanical system. The algorithm is verified by real-world data describing micro-mechanical piezo-actuators. The whole algorithm works for sparse descriptor form of the system. The piezo-mechanical original system is a second order index-1 descriptor system, where mass, damping, stiffness, input and output matrices are highly sparse. Several techniques are introduced to reduce the system into a first order index-1 descriptor system by preserving the sparsity pattern of the original models. Several numerical experiments are used to illustrate the efficiency of the algorithm.

Die Arbeit ist der regelungstheoretischen Betrachtung von mechanischen Systemen mit mehr Freiheitsgraden als Stellgrößen gewidmet. Dabei werden Aspekte aus den Teilgebieten Modellbildung, Systemanalyse, Steuerungsentwurf und Reglerentwurf behandelt. Den Ausgangspunkt bilden die aus dem Lagrange-Formalismus resultierenden Bewegungsgleichungen, für welche neben verschiedene partiell linearisierten Zustandsdarstellungen auch eine spezielle Byrnes-Isidori-Normalform eingeführt wird. Im Unterschied zu einer früher vorgeschlagenen ähnliche Normalform existiert diese "Lagrange-Byrnes-Isidori-Normalform" immer. Weiterhin wird die bedeutende Eigenschaft der differentiellen Flachheit im Zusammenhang mit mechanischen Systemen untersucht. Die bestehende Lücke zwischen den bekannten notwendigen und hinreichenden Flachheitsbedingungen bildet die Motivation zur Anpassung der Regelflächenbedingung auf mechanische Systeme in Lagrange-Byrnes-Isidori-Normalform. Parallel dazu wird die Flachheitsanalyse auf Basis des sogenannten Variationssystems betrachtet. Dabei handelt es sich um ein System von 1-Formen, die durch Anwendung der äußeren Ableitung auf die impliziten Systemgleichungen entstehen. Äquivalent dazu können auch die in einer rechteckigen Polynommatrix bezüglich des Zeitableitungsoperators zusammengefassten Koeffizienten der Basisformen untersucht werden. Die Flachheit eines Systems ist nun gerade äquivalent zur Existenz einer unimodularen Vervollständigung dieser Matrix, welche zudem noch eine bestimmte Integrabilitätsbedingung erfüllen muss. Durch Anwendung des Satzes von Frobenius können aus diesen in der bisherigen Formulierung nur schwer überprüfbaren Bedingungen deutlich einfachere hergeleitet werden. Für den Eingrößenfall ergibt sich dadurch eine erheblich Verringerung des Rechenaufwandes im Vergleich zum Referenzansatz. Im Mehrgrößenfall ist die Situation komplizierter: Durch das Fallenlassen der Unimodularitätsforderung und die Ausnutzung der speziellen Struktur mechanischer Systeme erhält man eine neue notwendige Bedingung für Flachheit, welche sich in endlich vielen Schritten auswerten lässt. Allerdings konnte mit dieser die vermutete Nichtflachheit für die untersuchten mechanischen Beispielsysteme nicht nachgewiesen werden. Einen weiteren Untersuchungsgegenstand bildet das Konzept der Konfigurationsflachheit. Für diese Eigenschaft ist gefordert, dass ein flacher Ausgang existieren muss, der nur von den Konfigurationskoordinaten abhängt. Basierend auf theoretischen Überlungen und dem Fehlen von Gegenbeispielen wird die Hypothese aufgestellt, dass für konservative mechanische Systeme Flachheit und Konfigurationsflachheit äquivalent sind. Für lineare mechanische Systeme kann diese Hypothese mit Hilfe der Kronecker-Normalform von Matrizenscharen verifiziert werden. Bezüglich des Entwurfs von Solltrajektorien werden neben der Darstellung bekannter Verfahren für lineare und für flache Systeme zwei weitere Ansätze genauer diskutiert. Der erste basiert auf der numerischen Lösung des aus dem Steuerungsentwurf resultierenden Randwertproblems. Dazu wird ein angepasstes Kollokationsverfahren konstruiert, welches die Elimination von Systemgrößen durch die explizite Berücksichtigung von Integratorketten ermöglicht, die bei partiell linearisierten Systemen stets auftreten. Unter bestimmten Bedingungen bewirkt dies eine erhebliche Reduktion der Rechenzeit. Der zweite Ansatz betrachtet die Überführung zwischen zwei Ruhelagen und beruht auf der Zeitumkehrsymmetrie, die alle konservativen mechanischen Systeme aufweisen. Er besteht aus mehreren Schritten: Zunächst wird für beide Ruhelagen eine Rückführung mit möglichst großem Attraktivitätsgebiet entworfen. Danach wird das System simulativ ausgehend von der Zielruhelage in der Startruhelage stabilisiert. Die so erhaltene Eingangstrajektorie kann dann bezüglich der Zeit invertiert werden, um das System aus der Startruhelage in die Nähe der Zielruhelage zu überführen, wo schließlich der entsprechende Regler aktiviert wird. In praktischen Realisierungen von unteraktuierten Regelungssystemen treten auf Grund von Effekten wie trockener Reibung und Getriebespiel oft Dauerschwingungen mit schwer vorhersagbaren und beeinflussbaren Parametern auf. Als Alternative zur klassischen Stabilisierung einer (theoretischen) Ruhelage wird deshalb eine Rückführung hergeleitet, welche für ein gegebenes lineares System einen stabilen Grenzzyklus mit vorgebbarer Frequenz und Amplitude asymptotisch stabilisiert.

Les récupérateurs d'énergie vibratoire électrostatiques (REV) sont des systèmes convertissant une partie de l'énergie cinétique de leur environnement en énergie électrique, afin d'alimenter de petits systèmes électroniques. Les REV inertiels sont constituées d'un sous-système mécanique bâti autour d'une masse mobile, ainsi que d'une interface électrique. Ces deux blocs sont couplés par un transducteur électrostatique. Cette thèse étudie l'amélioration des performances des REV par la conception optimisée de leur interface électrique. La première partie de cette thèse étudie une famille d'interfaces électriques appelées pompes de charge (PC). On commence par la construction d'une théorie formelle des PC. Des interfaces rapportées dans la littérature sont identifiées comme membres de cette famille. Cette dernière est ensuite complétée par une nouvelle topologie de PC. Une comparaison des différents PC est alors faite dans le domaine électrique, puis un outil semi-analytique est présenté pour la comparaison des PC en prenant en compte le couplage électromécanique. L'étude des PC se termine par la présentation d'une nouvelle méthode de mesure du potentiel d'électret des REV. La deuxième partie de la thèse présente une approche de conception radicalement différente de ce qui est présenté dans les travaux actuels sur les REV. Elle préconise une synthèse active de la dynamique de la masse des REV à travers leur interface électrique. Nous montrons d'abord que cela permet la conversion d'énergie en quantités proches des limites physiques, et ce à partir de vibrations d'entrée de forme arbitraire. Enfin, une architecture pour un tel REV est proposée et testée en simulation. / Electrostatic vibration energy harvesters (e-VEHs) are systems that convert part of their surroundings' kinetic energy into electrical energy, in order to supply small-scale electronic systems. Inertial E-VEHs are comprised of a mechanical subsystem that revolves around a mobile mass, and of an electrical interface. The mechanical and electrical parts are coupled by an electrostatic transducer. This thesis is focused on improving the performances of e-VEHs by the design of their electrical interface. The first part of this thesis consists in the study of a family of electrical interfaces called charge-pumps conditioning circuits (CPCC). It starts by building a formal theory of CPCCs. State-of-the-art reported conditioning circuits are shown to belong to this family. This family is then completed by a new CPCC topology. An electrical domain comparison of different CPCCs is then reported. Next, a semi-analytical tool allowing for the comparison of CPCC-based e-VEHs accounting for electromechanical effects is reported. The first part of the thesis ends by presenting a novel method for the measurement of e-VEHs' built-in electret potential. The second part of the thesis presents a radically different design approach than what is followed in most of state-of-the-art works on e-VEHs. It advocates for e-VEHs that actively synthesize the dynamics of their mobile mass through their electrical interface. We first show that this enables to convert energy in amounts approaching the physical limits, and from arbitrary types of input vibrations. Then, a complete architecture such an e-VEH is proposed and tested in simulations submitted to human body vibrations.

This paper describes the changes made from Cal Poly’s initial railgun system, the Mk. 1 railgun, to the Mk. 1.1 system, as well as the design, fabrication, and testing of a newer and larger Mk. 2 railgun system. The Mk. 1.1 system is developed as a more efficient alteration of the original Mk. 1 system, but is found to be defective due to hardware deficiencies and failure, as well as unforeseen efficiency losses. A Mk. 2 system is developed and built around donated hardware from the Naval Postgraduate School. The Mk. 2 system strove to implement an efficient, augmented, electromagnetic railgun and projectile system capable of firing an approximate 1g aluminum projectile to speeds exceeding 2 km/s. A novel three part projectile is proposed to mitigate rail and projectile degradation. Projectile and sabot system kinematic equations are derived and the projectile is designed and tested along with Mk. 2 barrel. A numerical electromechanical model is developed to predict the performance of the Mk. 2 system and projectile assembly, and predicts a final velocity for the fabricated system exceeding 3.5 km/s and an efficiency as high as 24%. Testing of the Mk. 2 system showed catastrophic failure of the projectile during initial acceleration, resulting in very short acceleration times and distance, low velocity projectiles, and low efficiencies. During further testing of various projectile configurations, the barrel structure failed due to a large internal arc. Future work for the Mk. 2 system is discussed, a revised external barrel structure suggested, and a solid, more conventional solid chevron projectile design suggested.

The objective of this thesis is to develop vibration-based fault detection strategies for on-line condition monitoring of gear transmission systems. The study divides the thesis into three sections. First of all, the local stresses created by a root fatigue crack on a pinion spur gear are analyzed using a quasi-static finite element model and non-linear contact mechanics simulation. Backlash between gear teeth which is essential to provide better lubrication on tooth surfaces and to eliminate interference is included as a defect and a necessary part of transmission design. The second section is dedicated to fixed axis power trains. Torsional vibration is shown to cause teeth separation and double-sided impacts in unloaded and lightly loaded gearing drives. The transient and steady-state dynamic loading on teeth within a two stage crank-slider mechanism arising from backlash and geometric manufacturing errors is investigated by utilizing a non-linear multi-body dynamics software model. The multi-body model drastically reduces the computation time required by finite element methods to simulate realistic operation. The gears are considered rigid with elastic contact surfaces defined by a penalty based non-linear contact formulation. The third section examines a practical differential planetary transmission which combines two inputs and one output. Planetary gears with only backlash errors are compared to those containing both backlash and tooth defects under different kinematic and loading conditions. Fast Fourier Transform (FFT) analysis shows the appearance of side band modulations and harmonics of the gear mesh frequency. A joint time-frequency analysis (JTFA) during start-up reveals the unique vibration patterns for fixed axis gear train and differential planetary gear, respectively, when the contact forces increase during acceleration.

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.