References: p.71. / Contract DA36-039-AMC-03200(E). Grant DA-SIG-36-039-61-G14.

The background and motivation of this study are based on: (1) Energy saving and carbon emission reduction are the rising issues gaining more awareness and efforts worldwide. (2) Taiwan plans to build ¡§low-carbon cities¡¨ in order to implement the policy of greenhouse gas reduction. (3) The most direct and practical way to reduce carbon emissions is by saving energy. (4) Everyone has to use illumination sources. (5) ¡§Electro-Magnetic Induction Lamps¡¨ is a useful tool to achieve the goal of energy saving and carbon emission reduction. Thus the topic of this study is ¡§The Effectiveness Analysis and Strategy of Energy-efficient Lighting in Developing a Low Carbon City ¡V A Case on Electro-Magnetic Induction Lamps¡¨. The objectives of this study are: 1. To analyze the characteristics of ¡§Electro-Magnetic Induction Lamps¡¨ and their conformity with local and overseas energy-efficient lighting policies. 2. To analyze the effectiveness of lighting economics of the case companies before and after their adoption of ¡§Electro-Magnetic Induction Lamps¡¨. 3. To explore the possible obstacles and their solutions for lighting industry development of ¡§Electro-Magnetic Induction Lamps¡¨ in the public sectors¡¦ strategies to develop low-carbon cities in Taiwan. The main issues of this study are about energy-efficient lighting policies and the economical effectiveness of ¡§Electro-Magnetic Induction Lamps¡¨, which belong to policy research on energy-saving equipment and the lighting industry. Therefore three research methods: Literature Review, Case Study, and In-depth Interview were adopted to collect, compare, and analyze the data. The conclusions of this study are: 1. The characteristics of ¡§Electro-Magnetic Induction Lamps¡¨ are in conformance with energy-efficient lighting policies in Taiwan. 2. To provide the analysis result of the case companies¡¦ economic benefits after its adoption of ¡§Electro-Magnetic Induction Lamps¡¨. 3. To indicate the possible Dilemma of the lighting industry development of ¡§Electro-Magnetic Induction Lamps¡¨ and the energy-efficient lighting policies for the strategies to develop low-carbon cities in Taiwan. According to above research outcomes, three suggestions have been further proposed: 1. Users must change their concepts and habits of lighting usage in order to cultivate good energy-saving habits. 2. Users must select appropriate illumination sources according to their needs in order to achieve most effectiveness of lighting economics. 3. According to the needs of appropriate illumination sources, the government should promote and subsidize the development and use of ¡§Electro-Magnetic Induction Lamps¡¨.

A multi-frequency data acquisition system is realized for subsurface conductivity imaging of biological tissues. The measurement procedures of the system at different frequencies are same. The only difference between the single frequency experiments and the multi-frequency experiments is the hardware, i.e. the sensor and the power amplifier used in the single frequency experiments was different than that were used in the multi-frequency experiments. To avoid confusion the measurement system with which the single frequency experiments were performed is named as prototype system and the measurement system with which the multi-frequency experiments were performed is named as multi-frequency system. This system uses magnetic excitation (primary field) to induce eddy currents inside the conductive object and measures the resulting magnetic field due to eddy currents (secondary field). For this purpose, two differential-coil sensors are constructed / one is for the single frequency measurements and the other is for the multi-frequency measurements. Geometrically the coils are same, the only difference between them is the radius of the wires wound on them. The sensor consists of two differentially connected identical receiver coils employed to measure secondary field and in between the receiver coils is placed a transmitter coil, which creates the primary field. The coils are coaxial. In the prototype system the transmitter coil is driven by a sinusoidal current of 300 mA (peak) at 50 kHz. In the multi-frequency system the transmitter coil is driven by a sinusoidal current of 217 mA (peak), 318 mA (peak), 219 mA (peak) and 211 mA (peak) at 30 kHz, 50 kHz, 60 kHz and 90 kHz, respectively. A data acquisition card (DAcC) is designed and constructed on a printed circuit board (PCB) for phase sensitive detection (PSD). The equivalent input noise voltage of the card was found as $146.80 hspace{0.1 cm}nV$. User interface programs (UIP) are prepared to control the scanning experiments via PC (HP VEE based UIP, LabVIEW based UIP) and to analyze the acquired data (MATLAB based UIP). A novel sensitivity test method employing resistive ring phantoms is developed. A relation between the classical saline solution filled vessel (45mm radius, 10 mm depth) phantoms and the resistive ring phantoms is established. The sensitivity of the prototype system to saline solutions filled vessels is 13.2 $mV/(S/m)$ and to resistive rings is 155.02 mV/Mho while the linearity is 3.96$%$ of the full scale for the saline solution filled vessels and 0.12$%$ of the full scale for the resistive rings. Also the sensitivity of the multi-frequency system is determined at each operation frequency by using resistive ring phantoms. The results are in consistence with the theory stating that the measured signals are linearly proportional with the square of the frequency. The signal to noise ration (SNR) of the prototype system is calculated as 35.44 dB. Also the SNR of the multi-frequency system is calculated at each operation frequency. As expected, the SNR of the system increases as the frequency increases. The system performance is also tested with agar phantoms. Spatial resolution of the prototype system is found 9.36 mm in the point spread function (PSF) sense and 14.4 mm in the line spread function (LSF) sense. Spatial resolution of the multi-frequency system is also found at each operation frequency. The results show that the resolving power of the system to distinguish image details increases as the frequency increases, as expected. Conductivity distributions of the objects are reconstructed using Steepest-Descent algorithm. The geometries and the locations of the reconstructed images match with those of the real images. The image of a living tissue, a leech, is acquired for the first time in the literature. Magnetic conductivity spectroscopy of a biological tissue is shown for the first time in electrical conductivity imaging via contactless measurements. The results show the potential of the methodology for clinical applications.

This dissertation presents an investigation of miniaturized magnetic induction and permanent magnet (PM) machines, intended for use in a microengine. Similar to a macroscale turbogenerator, a microengine comprises a small, gas-fueled turbine engine for converting chemical fuel energy into mechanical power and an integrated electrical generator for converting mechanical power to electrical power. The microengine system is proposed as a revolutionary, high power-density source for portable electronics. In this research, miniaturized magnetic induction machines and PM machines were designed, fabricated, and characterized. Both types of machines used axially directed magnetic fields and were nominally 10 mm in diameter and 1.5-2.3 mm in thickness. Innovative microfabrication techniques were developed to demonstrate the feasibility of integrating magnetic machines within a bulk-micromachined, silicon-based microengine system. Two-phase, eight-pole induction machines were constructed within silicon substrates using Cu coils in a laminated, slotted ferromagnetic NiFe or CoFeNi stator core. Silicon etching, wafer bonding, and electrodeposition were used to form all of the magnetic machine components. The induction machines were characterized in motoring mode using tethered rotors and demonstrated motoring torques of up to 2.5 uN-m. Also, three-phase, eight-pole, surface wound PM machines were built using a hybrid microfabrication/assembly approach. The stators were fabricated by electroplating Cu coils on ferromagnetic NiFeMo (Moly Permalloy) substrates. The rotors were formed by assembling a magnetically patterned SmCo PM with a FeCoV (Hiperco 50) back iron. The PM machines were tested as generators with free-spinning rotors, powered by an air-driven spindle, and demonstrated 2.6 W of mechanical-to-electrical power conversion with continuous DC power generation of 1.1 W at 120 krpm rotor speed. The primary contributions of this work are (1) the demonstration of microfabricated magnetic machines integrated within bulk-micromachined silicon and (2) the demonstration of multi-watt power conversion from a microfabricated PM generator. These achievements represent progress in the ongoing development of silicon-based microengines, but in addition, the fabrication technologies and device structures may find application in other microsystems.

Contactless electrical impedance imaging technique is based upon the measurement of secondary electromagnetic fields caused by induced currents inside the body. In this study, a circular single-coil is used as a transmitter and a receiver. The purpose of this study is twofold: (1) to solve the induced current density distribution inside the realistic head model resulting from a sinusoidal excitation, (2) to calculate the impedance change of the same coil from the induced current distribution inside the head model. The Finite Difference Method is used to solve the induced current density in the head. The realistic head model is formed by seven tissues with a 1 mm resolution. The electrical properties of the model are assigned as a function of frequency. The quasi-stationary assumptions, especially for head tissues, are explored. It is shown that, numerical solution of only the scalar potential is sufficient to obtain the induced current density in the head below 10 MHz operating frequency. This simplification not only reduce the excessive size of the solution domain, but also reduces the number of unknowns by a factor of 4. For higher frequencies (depending on the application) induction and propagation effects become important. Additionally it is observed that dynamic monitoring of hemorrhage at any frequency seems feasible. It is concluded that the methodology provides useful information about the electrical properties of the human head via contactless measurements and has a potent as a new imaging modality for different clinical applications.

Wireless Underground Sensor Networks (WUSNs) are the networks of wireless sensors that operate below the ground surface. These sensors are either buried completely in soil medium, or placed within a bounded open underground space, such as underground mines and tunnels. WUSNs enable a wide variety of novel applications, including intelligent irrigation, underground structure monitoring, and border patrol and intruder detection. This thesis is concerned with establishing reliable and efficient communications in the network of wireless sensor nodes that are deployed in either soil medium or underground mines and tunnels. In particular, to realize WUSNs in soil medium, two types of signal propagation techniques including Electromagnetic (EM) waves and Magnetic Induction (MI) are explored. For EM wave-based WUSNs, the heterogeneous network architecture and dynamic connectivity are investigated based on a comprehensive channel model in soil medium. Then a spatio-temporal correlation-based data collection schemes is developed to reduce the sensor density while keeping high monitoring accuracy. For MI-based WUSNs, the MI channel is first analytically characterized. Then based on the MI channel model, the MI waveguide technique is developed in order to enlarge the underground transmission range. Finally, the optimal deployment algorithms for MI waveguides in WUSNs are analyzed to construct the WUSNs with high reliability and low costs. To realize WUSNs in underground mines and tunnels, a mode-based analytical channel model is first proposed to accurately characterize the signal propagation in both empty and obstructed mines and tunnels. Then the Multiple-Input and Multiple-Output (MIMO) system and cooperative communication system are optimized to establish reliable and efficient communications in underground mines and tunnels.

Traditional methods of teaching magnetic induction with lab investigations using a battery, wire and compass are best reserved for demonstration purposes to introduce this particular topic. The modern student who sits in a physics course also lives in a world filled with an increasing number of small portable devices that will eventually be charged wirelessly using some form of magnetic induction. The topic of magnetic induction needs to be placed in the modern context it deserves since the future of transmitting power will eventually be through wireless means. The wireless power transfer kit described in this report is designed to improve student understanding and the application of magnetic induction in an engaging, relevant manner. / text

The previous data acquisiton system developed for the electrical impedance imaging via contactless measurements is improved to obtain measurements with a faster scanning speed of 0.15 sec/mm2. This system uses magnetic excitation to induce currents inside the body and measures the magnetic fields of the induced currents with an axial gradiometer. Gradiometer consists of two differentially connected 10000-turn coils with diameter of 30 mm and a transmitter coil of 100-turn coil of diameter 30 mm placed and magnetically coupled between them. Transmitter coil is driven by a sinusoidal current of 200 mA (peak) whose frequency is 14.1 kHz. A Data Acquisition Card (DAcC) is designed and constructed on PCB, thus elliminates the use of the Lock-In Amplifier Instrument (LIAI) in the phase sensitive measurements. User interface programs to control the scanning experiments via PC (MATLAB Scanner 1.0, HP VEE Scanner 1.0) and to analyze the acquired data (Data Observer 1.0) are prepared. System performance tests for the DAcC are made. Error in the phase sensitive measurements is measured to be 0.6% of the test signals. Minimum magnetic field density that can be detected is found to be 7 DT. Output stage performance of the DAcC is improved by using an integrator instead of an amplifier in the output stage. In this manner, maximum linearity error is measured as 6.60*10-4 % of the full scale for the integrator circuit. Thermally generated voltage drift at the sensor output is measured to be 0.5 mV/minute in the ambient temperature. Overall normalized standard deviation at the output of the data acquisition system is observed as to be in the order of 10-4. Mathematical relation between the resistive rings and conductive phantoms is studied. It is derived that maximum resistor value that can be distinguished in the resistive ring experiment which is 461 F, corresponds to the phantom conductivity of 2.7 S/m. Field profiles (i.e., the voltage measurements) for the human left hand is obtained for the first time in literature, employing the LIAI. Agar objects with conductivity value of 1 S/m in a saline solution of 0.2 S/m are scanned and the field profiles are obtained using the DAcC. Image profiles of the scan fit well with the actual locations, geometries, and relative dimensions of the agar objects. A coil winding machine is prepared which enables the operator to design and wind up coils under self-controlled environment and conditions.

Submitted by Maike Costa (maiksebas@gmail.com) on 2017-05-24T13:42:31Z No. of bitstreams: 1 arquivototal.pdf: 3782473 bytes, checksum: 32dae2c7c7f319bb1f74f7a9be6d1239 (MD5) / Made available in DSpace on 2017-05-24T13:42:31Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3782473 bytes, checksum: 32dae2c7c7f319bb1f74f7a9be6d1239 (MD5) Previous issue date: 2016-05-25 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The Shape Memory Alloys (SMA) is part of an active material class due to a special characteristic, called Shape Memory Effect (SME) that can be activated by a thermal field. In general these materials are made by metallic alloys and belong to a group of conducting materials with electromagnetic properties when circulated by an electric current. If geometrically configured as an inductor and stimulated with an alternating current allows the variable magnetic induction provided by the magnetic flux inside the coil. Using the thermomechanical shape change and the magnetic induction characteristics, this paper presents a study and development of a variable inductor with an alloy Ni-Ti. This study is based in inductance variation through geometric variation of coils made of shape memory wire and keeping the magnetic permeability constant. It was also observed variations in magnetic inductance due to change in temperature through electrical current, showing a possible close relationship with the phase transformation temperature of the material. To collect the experimental results were necessary the development of SME inductors with ferrite nucleus. Results are presented for the inductance variation related to length and temperature variation of a SMA inductor. / As Ligas com Memória de Forma (LMF) fazem parte de uma classe de materiais ativos ou inteligentes por possuírem uma característica especial denominada de Efeito Memória de Forma (EMF) que pode ser ativado por um campo térmico. Por serem geralmente ligas metálicas estão no grupo dos materiais condutores e apresentam propriedades eletromagnéticas quando circulados por uma corrente elétrica. Se configurado geometricamente como um indutor e estimulado com uma corrente alternada possibilita a indução magnética variável proporcionada pelo fluxo magnético no interior das espiras. Aproveitando a característica termomecânica de mudança de forma e o efeito físico de indução magnética, este trabalho apresenta um estudo do desenvolvimento de um indutor variável com liga com memória de forma de NiTi. O estudo se baseou na variação da indutância pela variação geométrica das espiras construídas com fio com memória de forma e mantendo a permeabilidade magnética do núcleo constante. Foram observadas variações na indutância magnética devido à variação de temperatura provocada por corrente elétrica, demonstrando uma possível relação entre as temperaturas de transformação de fase do material. Para a coleta dos resultados experimentais foram desenvolvidos alguns indutores com LMF com núcleo de ferrite. São apresentados resultados da variação da indutância relacionados com a variação do comprimento e temperatura do indutor de LMF.

Magnetic induction tomography (MIT) is a non-invasive, soft field imaging modality that has the potential to map the electrical conductivity (σ) distribution inside an object under investigation. In MIT, a number of exciter and receiver coils are distributed around the periphery of the object. A primary magnetic field is emitted by each exciter, and interacts with the object. This induces eddy currents in the object, which in turn create a secondary field. This latter is coupled to the receiver coils and voltages are induced. An image reconstruction algorithm is then used to infer the conductivity map of the object. In this thesis, the application of MIT for volumetric imaging of objects with low conductivity materials (< 5 Sm-1) and dimensions < 1 m is investigated. In particular, two low conductivity applications are approached: imaging cerebral stroke and imaging the saline water in multiphase flows. In low conductivity applications, the measured signals are small and the spatial sensitivity is critically compromised making the associated inverse problem severely non-linear and ill-posed.The main contribution from this study is to investigate three non-linear optimisation techniques for solving the MIT inverse problem. The first two methods, namely regularised Levenberg Marquardt method and trust region Powell's Dog Leg method, employ damping and trust region strategies respectively. The third method is a modification of the Gauss Newton method and utilises a damping regularisation technique. An optimisation in the convergence and stability of the inverse solution was observed with these methods compared to standard Gauss Newton method. For such non linear treatment, re-evaluation of the forward problem is also required. The forward problem is solved numerically using the impedance method and a weakly coupled field approximation is employed to reduce the computation time and memory requirements. For treating the ill-posedness, different regularisation methods are investigated. Results show that the subspace regularisation technique is suitable for absolute imaging of the stroke in a real head model with synthetic data. Tikhonov based smoothing and edge preserving regularisation methods also produced successful results from simulations of oil/water. However, in a practical setup, still large geometrical and positioning noise causes a major problem and only difference imaging was viable to achieve a reasonable reconstruction.