The overwhelming prevalence of cardiac related deaths is the motivation behind this thesis to develop body centric antennas for wireless cardiac monitoring. Cardiac monitoring can diagnose a number of conditions including: arrhythmia, ischemia, premature atrial complexes, abnormal sinus rhythms, heart blocks, atrial fibrillation, and more. A body centric antenna operating within the ISM band (2.4-2.48GHz) has been designed, simulated, and tested. The simulation and testing indicate low mutual coupling between antennas of varying distances has been achieved. In addition, the simulation and testing indicate that a thin layer of skin over the test subject further reduces mutual coupling.

No description available.

Surgical correction of scoliosis is a complicated mechanical process. Understanding the loads applied to the spine and providing immediate feedback to surgeons during scoliosis surgery will prevent overloading, improve surgical outcome and patient safety. Long-term development of residual forces in the spinal instrument after surgery with the continual curvature changes over time has been unknown. The goal of this research work was to develop a wireless implantable sensor platform to investigate the loads during and after surgery. This thesis describes research leading to the design of a sensor platform that uses both 403 MHz and 2.45 GHz for wireless communication, and reports the resolution and accuracy of the built-in temperature sensor, the A/D accuracy of the sensing platform, the power consumption at different operation modes, the range of the wireless communication and the discharge characteristics of a potential capacitive power module. / Biomedical Engineering

京都大学 / 0048 / 新制・論文博士 / 博士(人間健康科学) / 乙第13171号 / 論人健博第5号 / 新制||人健||4(附属図書館) / 京都大学大学院医学研究科人間健康科学系専攻 / (主査)教授 十一 元三, 教授 木下 彩栄, 教授 伊佐 正 / 学位規則第4条第2項該当 / Doctor of Human Health Sciences / Kyoto University / DFAM

No description available.

abstract: The ability to monitor electrophysiological signals from the sentient brain is requisite to decipher its enormously complex workings and initiate remedial solutions for the vast amount of neurologically-based disorders. Despite immense advancements in creating a variety of instruments to record signals from the brain, the translation of such neurorecording instrumentation to real clinical domains places heavy demands on their safety and reliability, both of which are not entirely portrayed by presently existing implantable recording solutions. In an attempt to lower these barriers, alternative wireless radar backscattering techniques are proposed to render the technical burdens of the implant chip to entirely passive neurorecording processes that transpire in the absence of formal integrated power sources or powering schemes along with any active circuitry. These radar-like wireless backscattering mechanisms are used to conceive of fully passive neurorecording operations of an implantable microsystem. The fully passive device potentially manifests inherent advantages over current wireless implantable and wired recording systems: negligible heat dissipation to reduce risks of brain tissue damage and minimal circuitry for long term reliability as a chronic implant. Fully passive neurorecording operations are realized via intrinsic nonlinear mixing properties of the varactor diode. These mixing and recording operations are directly activated by wirelessly interrogating the fully passive device with a microwave carrier signal. This fundamental carrier signal, acquired by the implant antenna, mixes through the varactor diode along with the internal targeted neuropotential brain signals to produce higher frequency harmonics containing the targeted neuropotential signals. These harmonics are backscattered wirelessly to the external interrogator that retrieves and recovers the original neuropotential brain signal. The passive approach removes the need for internal power sources and may alleviate heat trauma and reliability issues that limit practical implementation of existing implantable neurorecorders. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2014

This dissertation explores the applicability of RC helicopters as a tool to map wind conditions. This dissertation presents the construction of a robust instrumentation system capable of wireless in-situ measurement and mapping of ship airwake. The presented instrumentation system utilizes an RC helicopter as a carrier platform and uses the helicopter's dynamics for spatial 3D mapping of wind turbulence. The system was tested with a YP676 naval training craft to map ship airwake generated in controlled heading wind conditions. Novel system modeling techniques were developed to estimate the dynamics of an instrumented RC helicopter, in conjunction with onboard sensing, to estimate spatially varying (local) wind conditions. The primary problem addressed in this dissertation is the reliable estimation and separation of pilot induced dynamics from the system measurements, followed by the use of the dynamics residuals/discrepancies to map the wind conditions. This dissertation presents two different modelling approaches to quantify ship airwake using helicopter dynamics. The helicopter systems were characterized using both machine learning and analytical aerodynamic modelling approaches. In the machine learning based approaches, neural networks, along with other models, were trained then assessed in their capability to model dynamics from pilot inputs and other measured helicopter states. The dynamics arising from the wind conditions were fused with the positioning estimates of the helicopter to generate ship airwake maps which were compared against CFD generated airwake patterns. In the analytical modelling based approach, the dynamic response of an RC helicopter to a spatially varying parameterized wind field was modeled using a 30-state nonlinear ordinary differential equation-based dynamic system, while capturing essential elements of the helicopter dynamics. The airwake patterns obtained from both types of approach were compared against anemometrically produced wind maps of turbulent wind conditions artificially generated in a controlled indoor environment. Novel hardware architecture was developed to acquire data critical for the operation and calibration of the proposed system. The mechatronics design of three prototypes of the proposed system were presented and performance evaluated using experimental testing with a modified YP676 naval training vessel in the Chesapeake Bay area. In closing, qualitative analysis of these systems along with potential applications and improvements are discussed to conclude this dissertation. / Ph. D. / Ship airwake is a trail of wind turbulence left behind the superstructure of cruising naval vessels and are considered as a serious safety concern for aviators during onboard operations. Prior knowledge of the airwake distribution around the ship can alert pilots of possible hazards ahead of time and mitigate operational risks during the launch and recovery of the aircraft on the flight deck. This dissertation presents a novel application of Remote Control (RC) helicopters as tools to measure and map ship airwake. This dissertation presents two approaches to extract wind conditions from helicopter dynamics: (1) using machine learning based modeling, and (2) using analytic aerodynamic modeling-based estimation. Machine Learning is a modern engineering tool to model and simulate any system using experimental data alone. Under the machine learning based approach, the helicopter’s response to pilot inputs was modeled using multiple algorithms, with experimental flight data collected the absence of the ship airwake. With an assumption of capturing all the aerodynamic effects with the machine learning algorithms, the deviations in the dynamics estimates during testing environment were used to characterize and map ship airwake. In contrast to the machine learning model, the analytical approach modeled all critical aerodynamic processes of the RC helicopter as functions of pilot inputs and wind conditions using well defined physics laws, thus eliminating any need for training data. This approach predicts wind conditions on the basis of the model’s capability to match the estimates of helicopter dynamics to the actual measurements. Both presented approaches were tested on wind conditions created in indoor and outdoor environments. The performance of the proposed system was evaluated in experimental testing with a modified YP676 naval training vessel in the Chesapeake Bay area. The dissertation also presents the mechatronic design details of the novel hardware prototypes and subsystems used in the various studies and experiments. Finally, qualitative analysis of these systems along with their potential applications and improvements are discussed to conclude this dissertation.

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Electrical Engineering at the Cape Peninsula University of Technology, 2012 / This research project addresses the unique challenges of extensive farming in terms of monitoring and controlling remote equipment or events. Poorly maintained roads and escalating fuel costs increase difficulty of farming and the time spent on physically monitoring remote sites further reduces financial yields. The research showed that there are very few solutions that implement wireless or electronic technology to overcome the challenges associated with these isolated and arid areas and that a low-cost, long range wireless telemetry solution that is easy to use would be beneficial for the extensive farming industry. It was therefore the aim of this project to develop a remote monitoring and controlling solution that implements wireless technology to convey information of activities around the farm utilising electronic means. To be able to successfully develop a wireless telemetry solution that will accurately meet the needs of this specific sector of industry, market research was conducted. To guide the research, the QFD (quality function deployment) process for product development has been implemented. The research consisted out of various aspects including a survey, financial considerations and international comparisons. The research also aided in the understanding of the day-to-day activities and also the physical parameters of extensive farms. Also, currently available technologies and products were evaluated to establish whether similarities exist that will aid in the development of a new product. The development process was based on the results obtained in the market research and resulted in a wireless telemetry solution that overcame all the design challenges and proved to be technically feasible, successfully addressing the application requirements. Zigbee technology was utilized for wireless communication because it provided an off-the-shelf solution with a number of readily available development platforms from various technology providers. A communication range of up to 6 kilometres with a transmitted power of 11dBm was achieved for point-to-point communication and a mesh network topology has been implemented for even longer range and complete coverage on farms. Various types of measurements have been catered for, with custom-designed instrumentation which enabled measurements such as water levels, movement and analogue signals. Also, a basic user interface was developed to enable the user to monitor or control the equipment or events remotely from a personal computer, locally or even over the internet. The results of this research project showed that by carefully selecting available technologies and understanding the application, it is possible to develop a solution that addresses the monitoring and controlling needs associated with extensive farming. The wireless telemetry system that was developed resulted in a saving equal to 10% of the total expenses of the farms per year. The telemetry system is therefore a financially feasible solution with a payback period of less than 1 year and far below the initial estimated budget. Without the need to physically monitoring equipment and events, an increase in productivity and the expansion of the overall enterprise is a further benefit added unto the monetary savings. In addition to the financial benefits of implementing new wireless technology, this is an opportunity to contribute to a cleaner and more sustained future as a legacy for the next generation by reducing the carbon footprint of the farm.

[pt] Os sistemas eletromagnéticos de telemetria através de formações geológicas têm sido cada vez mais estudados na última década devido às importantes aplicações de engenharia para a indústria de exploração de óleo e gás. Várias técnicas computacionais puramente numéricas têm sido utilizadas para modelar esses cenários. No entanto, elas exigem um tratamento ardiloso para às bruscas mudanças na condutividade elétrica presente nas formações geológicas. Além disso, o custo computacional necessário para o processo de discretização é muito grande, e as instabilidades em baixas frequências se tornam críticas para problemas em que largas escalas estão envolvidas. Esta pesquisa apresenta uma formulação semianalítica para analisar a propagação dos campos eletromagnéticos em um meio estratificado, dissipativo, e com anisotropia biaxial. A solução proposta emprega uma nova abordagem no domínio espectral onde uma integral baseada na transformada de Hankel é apresentada para modelar a propagação de ondas devido a fontes de corrente do tipo anel com simetria azimutal. O método proposto é empregado para a análise de cenários geofísicos análogos aos do Pré-Sal brasileiro, onde rochas carbonáticas de alta condutividade são predominantes. Além disso, o efeito das formações do pré e pós-sal nos campos eletromagnéticos e sua interação com o tubo metálico que reveste o poço de petróleo é então computado para ambientes isotrópicos e anisotrópicos. É apresentada uma série de resultados de validação que mostram que a técnica proposta é numericamente estável, robusta e computacionalmente eficiente para modelar vários problemas representativos de telemetria sem fio em poços de petróleo. / [en] Electromagnetic telemetry systems through complex geological formations have been increasingly investigated in the last decade due to important engineering applications for the oil and gas industry exploration. Many brute-force computational electromagnetic techniques have been used for modeling this scenario. However, they require a tricky treatment of the large conductivity contrasts present in the soil formations. Also, high-cost computational resources are required for the discretization process and the low-frequency instabilities become critical for such large-scale problems. This research presents a semi-analytic formulation for analyzing the electromagnetic field propagation in a biaxially anisotropic and lossy stratified media. The proposed solution employs a novel spectral domain approach where a Hankel-based integral transform is introduced for modeling wave propagation due to azimuthally symmetric current loop sources. The proposed method is employed for analyzing geophysical scenarios analogous to those of the Brazilian Pre-Salt, where high conductivity carbonate rocks are prevalent. Also, the effect of the pre and post-salt formations on the electromagnetic fields and its interaction with the metallic casing of an oil well is then computed for both isotropic and anisotropic environments. It is presented a series of validation results which show that the proposed technique is numerically stable, robust and computationally efficient for modeling several representative problems of wireless oil well telemetry.

[pt] Neste trabalho são analisadas junções entre guias coaxiais não homogêneos com perdas. A expansão modal dos campos eletromagnéticos em um guia coaxial com duas camadas radiais é detalhadamente deduzida, e posteriormente a formulação é generalizada para guias com multicamadas radiais. As constantes de propagação para guias com perdas são determinadas pelo método do winding number, garantindo que todos os autovalores possam ser encontrados. O método do casamento de modos é aplicado na análise e projeto de estruturas coaxiais. A formulação é aplicada na otimização de estruturas de acoplamento e cornetas radiantes com carregamento dielétrico não homogêneo. O preenchimento não homogêneo é empregado nas estruturas radiantes a fim de minimizar a perda de retorno, e principalmente controlar e melhorar o formato do diagrama de radiação para operação em banda larga. Adicionalmente, a formulação é utilizada para analisar a propagação eletromagnética em sistemas de telemetria sem fio para poços de petróleo. / [en] In this work, we analyzed junctions between coaxial waveguides heterogeneously filled with lossy dielectrics. The modal expansion of the electromagnetic fields in a coaxial waveguide with two radial layers is derived in detail, and afterward the formulation is generalized for a multilayer waveguide. The propagation constants for lossy waveguides are determined through the method of winding number, ensuring that all eigenvalues can be found. The mode matching technique is applied in the analysis and design of coaxial structures. The formulation is applied in the optimization of coupling structures and radiating horns with heterogeneous dielectric loading. The heterogeneous filling is used in radiating structures in order to reduce the return loss, and especially to control and improve the shape of the radiation pattern for broadband operation. Additionally, the formulation is used to analyze the electromagnetic propagation in wireless telemetry systems for oil wells.