<p> Real-time rotor position and speed information is essential for effective power control of permanent magnet synchronous generator-based wind energy conversion systems. The presence of traditional encoders can increase the size, cost and complexity, but also reduce the overall system life-time and reliability. To provide a more reliable sensorless wind generation control scheme and eliminate the reliance on encoders, this paper presents a novel high order sliding mode observer for power control of permanent magnet synchronous generator-based wind energy conversion systems. Compared with the first order sliding mode observer, a high order sliding mode observer shows superior estimation accuracy with significantly reduced chattering effect. A three-level neutral-point-clamped space vector pulse width modulation (NPC-SVPWM) based power converter is used to reduce the voltage stress on power switching devices and produce less harmonics in the output waveforms compared with a traditional two-level inverter. Computer simulation results have shown the superior performance of the purposed high order sliding mode observer in wind turbine power control applications.</p>

<p> In this dissertation, a novel approach to modeling the scattered field of a periodic corrugated cylinder, from an oblique incident planewave, is presented. The approach utilizes radial waveguide approximations for fields within the corrugations, which are point matched to approximated scattered fields outside of the corrugation to solve for the expansion coefficients. The point matching is done with TMz and TEz modes simultaneously, allowing for hybrid modes to exist.</p><p> The derivation of the fields and boundary conditions used are discussed in detail. Axial and radial propagating modes for the scattered fields are derived and discussed. Close treatment is given to field equations summation truncation and conversion to matrix form, for numerical computing. A detailed account of the modeling approach using Mathematica&reg; and NCAlgebra for the noncommutative algebra, involved in solving for the expansion coefficients, are also given.</p><p> The modeling techniques offered provide a full description and prediction of the scattered field of a periodic corrugated cylinder. The model is configured to approximate a smooth cylinder, which is then compared against that of a textbook standard smooth cylinder. The methodology and analysis applied in this research provide a solution for computational electromagnetics, RF communications, Radar systems and the like, for the design, development, and analysis of such systems. Through the rapid modeling techniques developed in this research, early knowledge discovery can be made allowing for better more effective decision making to be made early in the design and investigation process of an RF project. </p>

<p> Health Monitoring Systems (HMS) are used to monitor physiological signals such as the blood pressure, heart rate, and temperature of patients. The use of a HMS for continuous monitoring of the Vital Signs of patients requiring constant medical supervision, is particularly important. The current project presents the development and implementation of a multi-sensor HMS to track and record multiple parameters of a patient (Electrocardiogram, pulse, temperature, and body position). The project development uses biomedical sensor technology for monitoring the physiological signals, Radio Frequency Identification (RFID) technology for patient identification, and the Internet of Things (IoT) for information transmission. Sensors attached to a patient&rsquo;s body collect data that alert users to abnormal values via smart devices, such as mobile phones or laptops. Experimental testing of the multi-sensor HMS developed and implemented for this project, demonstrates the system&rsquo;s effectiveness in sensing, collecting, and transmitting accurate patient information for remote monitoring.</p>

With CMOS scaling continuing to sub-10 nm node, Si is approaching its physical limits. To enable further scaling, alternative channel materials with superior transport properties are proposed to replace Si in the channel. III-V/Ge emerge as promising channel materials for NMOS/PMOS, respectively. The low-power and high-speed nature of these devices represents a strong incentive for their applications in space. However, to apply them in harsh radiation space environment, their radiation responses have to be investigated. In this dissertation, single-event-transient and total-ionizing-dose effects are investigated in III-V MOSFETs with different architectures. Heavy-ion irradiations, pulsed-laser irradiations, and TCAD simulations are performed to understand their radiation response. Similar to III-V FETs with non-insulating gate, III-V MOSFETs show excess vulnerability to single-event-effects (SEE) compared with their silicon counterparts. Aside from the charge deposited in the sensitive region by the radiation, III-V MOSFETs collect additional charge contributed by an activated parasitic bipolar transistor. Although the activation process varies in detail among different architectures, the key process is the same. Slow holes pile up around the source and channel and reduce the source-to-channel barrier, which causes electrons injecting from the source and collected by the drain. Bipolar amplification factor around 5-10 is measured, posing serious concerns over their space applications. Unlike the almost perfect Si/SiO2 interface, oxides on III-V materials are usually defective and when electrically stressed, charge trapping will happen. Therefore, combined electrical stress and biased X-ray irradiation measurements are performed. It shows that electrical stress-induced electron trapping compensates radiation-induced hole trapping during positive gate-bias irradiation. Stress-induced hole trapping adds to the effects of radiation-induced hole trapping under negative gate bias. These device level works provide early insights into the radiation effects on III-V MOSFETs and further circuit level analysis.

<p> Space-Time Code (STC) has caused wide public concern in the field of wireless communications over the recent years. Due to interference or signal attenuation, it may cause errors or data loss when the data stream is transmitted through a wireless channel. The Space-Time Block Code (STBC), which combines the technique of channel coding and antenna diversity, is an effective approach of increasing the capacity of a wireless channel by increasing both the coding gain and diversity gain. Using STBC in Orthogonal Frequency-Division Multiplexing (OFDM), multiple antennas transmit multiple copies of the data stream, and the receiver can integrate these copies for optimal data. In this system, the wireless signal is more reliable and able to meet more remote wireless transmissions. In this project, three STBCs are applied in 2x1, 3x1, and 4x1 OFDM system respectively, to provide different data rates and reliability. </p>

<p> The objective of this thesis is to compute the Misadjustment of Adaptive Predictors and to implement their fixed-point design on Xilinx Vivado for a behavioral simulation of the Prediction Gain. In the first part of this thesis, the Misadjustment is mathematically calculated for Adaptive Predictors of different tap-weights. These Adaptive Predictors include Least Mean Square (LMS), Forward-Backward LMS (FBLMS), Cascaded LMS (CLMS), and Cascaded Forward-Backward LMS (CFBLMS) for 2, 4, and 6 tap-weights. In the second part of this thesis, the 6-Tap design of all the four predictors is programmed in Verilog Hardware Description Language (HDL) using MATLAB&rsquo;s HDL Coder tool and run on the Xilinx Vivado platform for comparing behavioral simulations of the Prediction Gain with that obtained on MATLAB. An alternative method for the Prediction Gain comparison is accomplished by instantiating Xilinx Analog-to-Digital Converter (XADC) block available on 7-series Field-Programmable Gate Array (FPGA) boards as a means to introduce the input signals as voltage values. </p><p> Misadjustment is determined for 2, 4, and 6 tap-weights on all four Adaptive Predictors previously mentioned for input signals such as a sinusoid of frequency 0.1Hz contaminated with White Gaussian Noise (WGN), a second-order Auto-Regressive (AR) process, and a speech signal at 8Kbps. The results in every case reveal that FBLMS and CFBLMS show better performance, in terms of Misadjustment, when compared to LMS and CLMS Adaptive Predictors, respectively. Also, irrespective of the input signals, only the 2-Tap cascaded Adaptive Predictors such as CFBLMS and CLMS exhibit lower Misadjustment than the 2-Tap non-cascaded FBLMS and LMS predictors. And, in the case of the second-order AR process input, if AR parameters are chosen so that the eigenvalue spread is sufficiently large, then the performance of 2-Tap, 4-Tap, and 6-Tap CFBLMS and CFLMS predictors have a lower Misadjustment than that of FBLMS and LMS predictors. </p><p> The Prediction Gain calculations for the speech signal input on all the four predictors reveal that the 6-Tap CFBLMS and CLMS Adaptive Predictors show much higher gains compared to 6-Tap FBLMS and LMS Adaptive Predictors. All four 6-Tap predictors, after quantization of tap-weights to reduced number of bits for a fixed-point design, are HDL programmed on Xilinx Vivado. The behavioral simulation for Prediction Gain obtained using both the methods described reveal that the result is nearly the same as the Prediction Gain value obtained using a MATLAB simulation thereby validating the fitness of the design for FPGA implementation. Also, instantiating the XADC block for introducing input voltages, rather than hardcoding input voltages as binary-coded-decimals into Testbench, gives the leeway to feed different sets of input signals directly as voltage parameters.</p>

<p> One of the major challenges faced by the blind and the visually impaired in their daily activities, is independent navigation in an urban setting. There may be protrusions, potholes, excavations, vehicles, etc. on their path. The main aim of the assistive devices is to make the visually impaired or the blind more independent and self-sufficient. White canes and guide dogs are the primitive mobility aids they use. Currently there are many Electronic Travel Aids (ETA) and Accessible Pedestrian Signals (APS) available in the market such as the smart canes, radix rotating cone, etc.</p><p> This project presents the development, hardware implementation and testing of an Electronic Travel Aid (ETA) system, which can be used by the blind or the visually impaired for independent navigation within an urban environment. The system uses nRf24L01+ radio modules to communicate information about the street grid to user. The information includes distance to the next intersection, structure of the intersection, intersection name, and pedestrian signal status. The information is received on a hand-held device and can be converted to a voice signal by a speech synthesis device.</p>

<p>The multidimensional joint distributions that represent complex systems with many</p><p>interacting elements can be computationally expensive to characterize. Methods</p><p>to overcome this problem have been introduced by a variety of scientific communities.</p><p>Here, we employ methods from statistics, information theory and statistical</p><p>physics to investigate some approximation techniques for inference over factor graphs</p><p>of spatially-coupled low density parity check (SC-LDPC) codes, estimation of the</p><p>marginals of stationary distribution in influence networks consisting of a number of</p><p>individuals with polarized beliefs, and estimation of per-node marginalized distribution</p><p>for an adoption model of polarized beliefs represented by a Hamiltonian energy</p><p>function.</p><p>The second chapter introduces a new method to compensate for the rate loss of</p><p>SC-LDPC codes with small chain lengths. Our interest in this problem is motivated</p><p>by the theoretical question of whether or not the rate loss can be eliminated by</p><p>small modications to the boundary of the protograph? We tackle this question by</p><p>attaching additional variable nodes to the check nodes at the chain boundary. Our</p><p>goal is to increase the code rate while preserving the BP threshold of the original</p><p>chain.</p><p>In the third chapter, we consider the diffusion of polarized beliefs in a social network</p><p>based on the influence of neighbors and the effect of mass media. The adoption</p><p>process is modeled by a stochastic process called the individual-based (IN-STOCH)</p><p>system and the effects of viral diffusion and media influence are treated at the individual</p><p>level. The primary difference between our model and other recent studies,</p><p>which model both interpersonal and media influence, is that we consider a third state,</p><p>called the negative state, to represent those individuals who hold positions against</p><p>the innovation in addition to the two standard states neutral (susceptible) and positive</p><p>(adoption). Also, using a mean-eld analysis, we approximate the IN-STOCH</p><p>system in the large population limit by deterministic differential equations which we</p><p>call the homogeneous mean-eld (HOM-MEAN) and the heterogeneous mean-eld</p><p>(HET-MEAN) systems for exponential and scale-free networks, respectively. Based</p><p>on the stability of equilibrium points of these dynamical systems, we derive conditions</p><p>for local and global convergence, of the fraction of negative individuals, to</p><p>zero.</p><p>The fourth chapter also focuses on the diffusion of polarized beliefs but uses a different</p><p>mathematical model for the diffusion of beliefs. In particular, the Potts model</p><p>from statistical physics is used to model the joint distribution of the individual's</p><p>states based on a Hamiltonian energy function. Although the stochastic dynamics</p><p>of this model are not completely dened by the energy function, one can choose any</p><p>Monte Carlo sampling algorithm (e.g., Metropolis-Hastings) to dene Markov-chain</p><p>dynamics. We are primarily interested in the stationary distribution of the Markov</p><p>chain, which is given by the Boltzmann distribution. The fraction of individuals in</p><p>each state at equilibrium can be estimated using both Markov-chain Monte Carlo</p><p>methods and the belief-propagation (BP) algorithm. The main benet of the Potts</p><p>model is that the BP estimates are asymptotically exact in this case.</p> / Dissertation

There is increasing interest in using commercial-off-the-shelf (COTS) electronics in radiation environments, such as robotic systems for remediation after the nuclear accident at Fukushima or in low-cost CubeSats. Commercial electronics have varying levels or robustness to radiation environments, and without extensive testing and redesign, the survivability of COTS systems in radiation environments is unknown and potentially insufficient. This work identifies characteristics of robotic commercial-off-the-shelf component degradation, primarily part-to part variability and the interactions between the degradation of multiple components. Insight into the health of a class of components, micro-controllers, was developed using timing characteristics. A framework using either continuous or discrete Bayesian networks was developed to model the degradation observed in sensors and other electronic components. The Bayesian network can be incorporated with deterministic models to produce a robust and scalable analysis methodology, granting awareness of how the system will behave in the radiation environment and providing insight into areas for improvement in the system hardware and software.

<p>Optimization of the geometry of a metallic bowtie gap at radio frequency is presented in this thesis. Since the design and fabrication of a plasmonic device (nanogap) at nanoscale is challenging, the results of this study can be used to estimate the best design parameters for nanogap structure. The geometry of the bowtie gap including gap size, tip width, metal thickness, and tip angle are investigated at macroscale to find the maximum electric field enhancement across the gap. This thesis focuses on the simulation portion of a work that consists of experimental and simulation platforms. The simulation platform is created by NEC modeling system using antenna segments. The results indicate that 90? bowtie with 0.06 ? gap size has the most |Et|2 enhancement. Different amounts of enhancement at different frequency ranges are explained by mode volume. The product of the mode volume and |Et|2 enhancement is constant for different gap structures and different frequencies.