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Measuring the in vivo load state of Total Knee Arthroplasty (TKA) components is required to understand the structural environment and wear characteristics of the devices. The ability to acquire this information gives tremendous insight into the mechanics of the joint replacement prosthesis. Data corresponding to normal loads, in-plane loads, shear loads, load center, contact area, and the rate of loading is needed to fully understand the kinematics and kinetics of the orthopedic implant. In this research, a novel sensing system has been developed which is capable of fully characterizing three-dimensional strain and stress at a single location. Capacitance-based sensors were chosen to avoid the power loss and drift characteristics typical of resistive elements due to resistive heating effects. A design and optimization methodology has been developed by combining conformal mapping electrostatic analysis techniques with methods from micromechanics of composite materials. Results of the design and optimization technique are used to understand the behavior of the sensing system. Simulation of these systems was performed using multiphysics finite element analysis, and novel methods for fabricating the sensors were adapted from techniques for fabricating microelectromechanical systems (MEMS) using biocompatible materials. An array of six sensors was fabricated with a critical dimension of 2.25 micrometers. This array consisted of a parallel plate capacitor for measuring normal strain, two differential elements for sensing shear strain normal to the plane of the array, and three interdigitated transducer (IDT) elements for characterizing strain in the plane of the sensor. The normal strain sensor exhibited a sensitivity of 1.54×10-3 picofarads per megapascal, and the shear sensor had a sensitivity of 4.77×10-5 picofarads per megapascal. Testing results showed that all sensors had linear response to loading and insignificant drift. Multiaxial testing results illustrated the ability of the differential sensors to determine loading direction. A multiaxial, MEMS sensor array has been developed for use in orthopedic, load-measuring conditions. This system has been optimized for use in soft materials such as ultra-high molecular weight polyethylene (UHMWPE). In the future, arrays of sensors will be embedded in orthopedic components to determine the total state of stress at local positions within the component.

Specific objectives of this study were to develop, prototype, and test a corn population sensor. Both intrusive mechanical and non-intrusive capacitive techniques have been used to develop the stalk population sensors in previous research. However, neither could generate consistent performance. The mechanical method required high maintenance and resulted in significant underestimations of stalk counts. The performance of capacitive systems was limited by inadequate sensing distance, especially at low stalk moisture levels. In this research, the sensitivity of the capacitive sensor was optimized for corn stalks. This system utilized a single-sided capacitive sensor, Wien bridge oscillator, phase-locked loop, and an operational amplifier to transform stalk presence to a change in electrical potential signal. The capacitive sensor patterns were simulated using the finite element method, which provided useful conceptual information. A number of different detection element patterns were modeled and tested. The patterns examined included single-sided two-plate, interdigital, polarized interdigital, semi-interdigital, and solid ground electrode. The key parameters affecting pattern sensitivity were investigated. The most promising pattern, the solid ground electrode, was selected for further evaluation and development. The solid ground electrode detection element was incorporated into circuitry including Wien-Bridge oscillator, a phase-locked loop used as a high-speed frequency-tovoltage converter, and an operational amplifier to provide impedance matching and maximize data acquisition resolution. The operational configuration, optimum operating parameters, and associated component sizes were determined using both modeling and laboratory testing. With an acceptable signal-sided pattern and signal-to-noise ratio, this sensing system was investigated in a realistic production environment. A preliminary field test was used to evaluate the sensor system (including a protective housing and mounting system) and data acquisition system to identify problems before conducting the final field test. Stalk moisture content and harvest speed were used as treatment blocks in the final test. The influences of environmental and mechanical noise and the noise-like influence of corn leaves and weeds were also investigated. The final field test accurately simulated realistic harvesting conditions and real-time data was collected for stalk identification analysis. Post-acquisition processing, feature extraction, and principal component analysis of the extracted features were performed on the raw field data. Three sensor signal features were selected to identify stalks. A backpropagation artificial neural network technique was used to develop the pattern classification model. Numerous neural network structures were evaluated and two-layer structure with four neurons in the first layer and one neuron in the second layer was selected based on maximum prediction precision and accuracy and minimum structure complexity. This structure was then evaluated to determine the prediction accuracy at various resolution levels. Results showed that the model can predict stalk population at 99.5% accuracy when the spatial resolution is 0.025 ha. The sensor can predict stalk population with a 95% accuracy when the resolution is a 9-meter row segment (approximately 10 seconds).

Point source extraction is critical to proper analysis of images containing point sources obtained by focal plane array cameras. Two popular methods of extracting the intensity of a point source are aperture photometry and point spread function fitting. Digital aperture photometry encompasses procedures utilized to extract the intensity of an imaged point source. It has been used by astronomers in various forms for calculating stellar brightness. It is also useful for doing analysis of data associated with other unresolved radiating objects. The various aperture photometry methods include the two-aperture method, aperture correction, and growth curve method. The growth curve method utilizes integrated irradiance within an aperture versus growing aperture size. Signal to noise ratio, imperfect backgrounds, moving and off centered targets, and noise structure are just a few of the items that can cause problems with point source extraction. This thesis presents a study of how best to apply the growth curve method. Multiple synthetic image sets were produced to replicate real world data. The synthetic images contain a Gaussian target of known intensity. Noise was added to the images, and various image related parameters were altered. The growth curve method is then applied to each data set using every reasonable aperture size combination to calculate the target intensity. It will be shown that for different types of data, the most optimal application of the growth curve method can be determined. An algorithm is presented that can be applied to all data sets that fall within the scope of this study will be presented.

We report results for the development of a flow-through integrated cavity absorption meter (ICAM.) Absorption measurements have been made with 2% or less change in the signal in the presence of up to 10 m-1 of scattering in the medium. The operating range of the ICAM ranges from 0.004 m-1 to over 40 m-1 of absorption. This range allows one to use a single instrument to measure the absorption from sediment laden rivers out to the cleanest of ocean waters. Further, the ICAM signal has been shown to be independent of the flow rate and turbulence in the medium. In addition we report the development of a diffuse reflector which, to our best knowledge, has the highest measured diffuse reflectivity of 0.998 at 532 nm and 0.996 at 266 nm. We also show that the average distance a photon travels between successive reflections in an integrating cavity of arbitrary shape is four times the volume divided by the surface area, 4 V/S. Further, for a cavity which is formed by planes tangent to an inscribed sphere and which maintains a homogeneous and isotropic field, the average distance traveled by a photon between successive reflections is equal to 4 V/S of the inscribed sphere. Thus, each cavity has the same ratio of V/S as the inscribed sphere. These advances lead to an increase in the sensitivity of absorption spectroscopy. The sensitivity approaches that of cavity ring down spectroscopy (CARS), without the adverse scattering effects traditionally associated with CARS.

Arcing from the pantograph, a commonly observed phenomenon, is knownto be a major source of wideband electromagnetic emission which is more pronounced during the winter. Experience within the railway industry has shown that this source of EMI and its characteristics need to be understood thoroughly for solving the associated EMI issues in the desired fashion. This thesis investigates EMI generation from pantograph arcing. The First phase of the work is based on experimental investigations and analyses conducted on a test setup which closely resembles pantographcontact wire interaction. Different possible mechanisms of the pantograph arcing and inuencing parameters like speed of the train, loadcurrent, voltage level, power factor etc. are identified. It was found that pantograph arcing is a polarity dependent phenomenon. It generates transients and asymmetrically distorted voltage and current waveforms. This in turn generates a net DC component and odd and even harmonics(up to order 10 was measured). In the second phase, different characteristics of these high frequency emission and inuencing parameters have been analyzed and presented. Presence of wideband high frequency components in the range from afew ten kHz to a few hundred MHz at measured current, electric and magnetic elds were confirmed. 10-90 % risetimes for current was measured from 5 ns to typically around 25 ns, whereas for electric field this is ranged from fraction of onens to 25 ns. Although there are variations, the rise times of the measuredtime domain waveform of current, electric and magnetic seems to have correlation with the higher frequency components. It was understood that major high frequency components measured could be from: (a) thearcing itself, (b) radiation from connected cables/wires, (c) resonance inthe associated circuits and (d) associated digital circuitry.This wideband electromagnetic emission causes interference in traction power, signalling and train control systems. Their possible propagation paths and consequences on different equipments are also elaborated. / QC 20100803

Biopotential signals are important to physicians for diagnosing medical conditions in patients. Traditionally, biopotentials are acquired using contact electrodes together with instrumentation amplifiers (INAs). The biopotentials are generally weak and in the presence of stronger common mode signals. The INA thus needs to have very good Common Mode Rejection Ratio (CMRR) to amplify the weak biopotential while rejecting the stronger common mode interferers. Opamp based INAs with a resistor-capacitor feedback are suitable for acquiring biopotentials with low power and low noise performance. However, CMRR of such INA topologies is typically very poor. In the presented research, a technique is proposed for improving the CMRR of opamp based INAs in RC feedback configurations by dynamically matching input and feedback capacitor pairs. Two instrumentation amplifiers (one fully differential and the other fully balanced fully symmetric) are designed with the proposed dynamic element matching scheme. Post layout simulation results show that with 1 percent mismatch between the limiting capacitor pairs, CMRR is improved to above 150dB when the proposed dynamic element matching scheme is used. The INAs draw about 10uA of quiescent current from a 1.5 dual power supply source. The input referred noise of the INAs is less than 3uV/sqrt(Hz).

Constantly growing need for oil, all over the world, has caused oil price to rise rapidly during the last decade. High oil prices have made fuel economy as one of the most important factors when consumers are buying their cars today. Realizing this, many car manufacturers have developed or are looking for some alternative solutions in order to decrease fuel consumption. Combining two different technologies in a vehicle, the so called hybrid vehicle, can be seen as the first step toward a better and more sustainable development. There are several different solutions for hybrid vehicles today, among the best known are the Serie Electric Hybrid Vehicle (SEHV), the Parallel Electric Hybrid Vehicle (PEHV) and the Serie-Parallel Hybrid Electric Vehicle (SPEHV). By integrating a combustion engine with a linear electric machine into one unit, a system that is called Free Piston Energy Converter (FPEC) is achieved. The FPEC is suitable for use in a SEHV. Other application areas like stand alone generator are also possible. In this report a novel Transverse Flux Machine (TFM) with a tubular cross section of the translator has been investigated. Application of the machine in a FPEC has put tough requirement on the translator weight, specific power and force density. Different configurations of the winding arrangements as well as the magne tarrangement have been investigated. It has been concluded that the buried magnet design suffers from high leakage flux and is thus not asuitable TFM concept. Instead the surface mounted magnet design has been chosen for further investigation. An analytical model has been developed and a prototype machine has been built based on the analytical results. In order to have a better understanding of the machine characteristic a 3D-FEM analysis has been performed. The results from the analytical model, FEM model and measurements are analyzed and compared. The comparison between the measured and FEM-simulated results shows very good agreement. Furthermore, the results from the analytical model indicates that it can be successfully developed for further analysis and optimization of the design to give a cost-effective solution of the novel generato for mass production. / Det ständigt växande behovet av oljan runt om i världen, har fått oljepriset att stiga snabbt under det senaste decenniet. Detta har gjort bränsleekonomin till en av de viktigaste faktorer när konsumenterna väljer sina bilar i dag. Många biltillverkare har därför utvecklat eller söker efter alternativa lösningar till dagens förbränningsmotorer i hopp om att minska bränsleförbrukningen. Ett hybridfordon, ett fordon som är försedd med fler än en energiomvandlare, kan ses som ett första steg mot en bättre och mer hållbar utveckling. Det finns flera olika lösningar för hybridfordon i dag, bland de mest kända är Seriehybrid, Parallellhybrid och Serie-Parallelhybridfordon. Genom att integrera en förbränningsmotor med en linjär elektriskmaskin, erhålls ett system som kallas Frikolvsenergiomvandlare. Dennna typ av energiomvandlare lämpar sig bäst för användning i en seriehybridfordon, men andra användningsområden som fristående generator är också möjliga. I denna avhandling har en ny typ av Transversalflödesmaskin (TFM) med en cirkulärt tvärsnitt undersökts. Tillämpningen av maskinen i en Frikolvsenergiomvandlare har medfört tuffa krav på translatorvikten, specifikeffekten och kraftdensiteten. Olika lindnings- och magnetkonfiguratationer har undersökts. Forskningen har visat att designen med begravdamagneter lider av stort läckflöde och är därför inte lämplig för det nya TFM koncept. Istället har designen med ytmonterade magneter valts för vidare undersökning. En analytisk modell har utvecklats och en prototyp maskin har byggts med utgångspunkt i analysresultaten. För att få en bättre förståelse avmaskinkarakteristiken har en 3D-FEM modell tagits fram och analyserats. Resultaten från den analytiska modellen, FEM modellen och mätningar har analyserats och jämförts. Överensstämmelsen mellan de simulerade och de uppmätta resultaten är mycket bra. Dessutom, resultaten från den analytiska modellen visar på att modellen kan framgångsrikt användas för fortsatt analys och optimering av maskinen för att ge en kostnadseffektivlösning för masstillverkning. / QC 20101102

The design of bicycle frames has remained fairly static for the majority of the past century, but recent increases in demand for high performance bicycles has created an accelerated design cycle that requires innovation. In order to design new frames with confidence in their capacity to withstand the rigors of use, reliable data about the nature of that use is needed, but this data is not currently available. The purpose of this research was to develop and implement a system that is capable of interpolating loads applied to a bicycle frame during vigorous riding for the purpose of improving the quality of information available to bicycle designers. The system that was developed employed finite element modeling to locate strain gauges on a frame and a least-squares approximate solution of strain readings to interpolate the applied loads. At its best, the system is capable of resolving loads with better than a 2% error. This system is limited, though, as it can only be applied in cases where the frame has a significant strain reaction to a load case but does not have a significant change in geometry during loading. This system was implemented on a cross-country mountain bicycle frame for the purposes of determining a rider weight to load relationship and to compare the standardized test procedures for bicycles to the loads experienced in the field. It was confirmed that there is a linear relationship between rider weight and load on the frame for all component forces except that applied to the bottom bracket, out of plane with the bicycle frame. It was also found that the British Standards fatigue testing practices, which are used internationally to assess bicycle safety, are inconsistent in their representation of realistic riding conditions when compared with the results from the field tests. Some loads appear conservative, some offer a very large factor of safety, and two are not represented at all. In particular, the moment about the bottom bracket due to pedaling and the load on the seat from the rider appear to consistently exceed the standardized test requirements while the moment caused by fork splay seems much smaller than the tests demand.

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