Engineering Commons^™

Fiber Optic Sensors For Industry And Military Applications, Yiyang Zhuang

Doctoral Dissertations

"Fiber optic sensors (FOSs) have been widely used for measuring various physical and chemical measurands owing to their unique advantages over traditional sensors such as small size, high resolution, distributed sensing capabilities, and immunity to electromagnetic interference. This dissertation focuses on the development of robust FOSs with ultrahigh sensitivity and their applications in industry and military areas.

Firstly, novel fiber-optic extrinsic Fabry-Perot interferometer (EFPI) inclinometers for one- and two-dimensional tilt measurements with 20 nrad resolution were demonstrated. Compared to in-line fiber optic inclinometers, an extrinsic sensing motif was used in our prototype inclinometer. The variations in tilt angle of the …

Protection Of Modern Distribution Systems, Fahd Amin Hariri

Doctoral Dissertations

“Motivated by the potential for improvements in the electric distribution system’s protection schemes, this work examined the challenges facing protection schemes due to the integration of Distributed Generators (DGs). Traditional protection schemes for radial distribution systems were designed based on the unidirectional power flow from the source down to the loads. Protective devices typically use are overcurrent relays, autoreclosers, fuses, and circuit breakers. However, these protective schemes may no longer be sufficient to ensure correct operation in the new era of distribution systems integrated by DGs. This research investigated the impact of DGs that might mislead the protection schemes in …

Emi Characterization For Power Supplies And Machine Learning Based Modeling In Emc/Si, Jiayi He

Doctoral Dissertations

"Signal integrity (SI) and electromagnetic interference (EMI) are essential for consumer electronics and high-speed server applications. It is necessary to do EMI and SI modeling at the design stage. In this research, several modeling approaches for EMI and SI problems are proposed. By using measurement-based modeling method, the mechanism of conducted emissions (CE) on ac to dc power supplies in an LED TV is analyzed. A system-level transient simulation model is built to predict the conducted emission (CE). To characterize the equivalent dipole moment sources in RFI and EMI problems, a dipole source reconstruction method based on machine learning techniques …

Fiber-Optic And Coaxial-Cable Extrinsic Fabry-Perot Interferometers For Sensing Applications, Chen Zhu

Doctoral Dissertations

”The fiber-optic extrinsic Fabry-Perot interferometer (EFPI) is one of the simplest sensing configurations and is widely used in various applications due to its prominent features, such as high sensitivity, immunity to electromagnetic interference, and remote operation capability. In this research, a novel one-dimensional wide-range displacement sensor and a three-dimensional displacement sensor based on fiber-optic EFPIs are demonstrated. These two robust and easy-to-manufacture sensors expand the application scope of the fiber-optic EFPI sensor devices, and have great potential in structural health monitoring, the construction industry, oil well monitoring, and geo-technology.

Furthermore, inspired by the fiber-optic EFPI, a novel and universal ultra-sensitive …

Adaptive Dynamic Programming Methods For Tracking Current Control Of Switched Reluctance Motor Drive, Hamad Alharkan

Doctoral Dissertations

“This research investigates the application of adaptive dynamic programming (ADP) methods for the current control of switched reluctance motors (SRM). Since the traditional current controllers have large current ripples that increase torque ripples and acoustic noise, optimal tracking controllers using reinforcement learning (RL) approaches are introduced as an alternative adaptive technique for SRM drives. The proposed optimal tracking controllers can minimize current ripples and cope with uncertainties within the inductance profile of the SRM. The work is composed of three papers. In the first paper, a novel Q-learning scheduling method for the current controller of a switched reluctance motor (SRM) …

Advanced Control Techniques For Modern Inertia Based Inverters, Sepehr Saadatman

Doctoral Dissertations

”In this research three artificial intelligent (AI)-based techniques are proposed to regulate the voltage and frequency of a grid-connected inverter. The increase in the penetration of renewable energy sources (RESs) into the power grid has led to the increase in the penetration of fast-responding inertia-less power converters. The increase in the penetration of these power electronics converters changes the nature of the conventional grid, in which the existing kinetic inertia in the rotating parts of the enormous generators plays a vital role. The concept of virtual inertia control scheme is proposed to make the behavior of grid connected inverters more …

System Efficient Esd Design Concept For Soft Failures, Giorgi Maghlakelidze

Doctoral Dissertations

"This research covers the topic of developing a systematic methodology of studying electrostatic discharge (ESD)-induced soft failures. ESD-induced soft failures (SF) are non-destructive disruptions of the functionality of an electronic system. The soft failure robustness of a USB3 Gen 1 interface is investigated, modeled, and improved. The injection is performed directly using transmission line pulser (TLP) with varying: pulse width, amplitude, polarity. Characterization provides data for failure thresholds and a SPICE circuit model that describes the transient voltage and current at the victim. Using the injected current, the likelihood of a SF is predicted. ESD protection by transient voltage suppressor …

An Emi Characterization And Modeling Study For Consumer Electronics And Integrated Circuits, Chunyu Wu

Doctoral Dissertations

“As internet-of-things (IoT) applications surge, wireless connectivity becomes an essential part of the network. Smart home, one of the most promising application scenarios of IoT, will improve our life quality enormously. However, electromagnetic interference (EMI) to the receiving antenna, either from another electronic product or from a module/an integrated circuit(IC) inside the same wireless device, will degrade the performance of wireless connectivity, thus influencing the user experience. Characterization and modeling of the EMI become increasingly important.

In the first part, an improved method to extract equivalent dipoles from magnitude- only electromagnetic-field data based on the genetic algorithm and back-and-forth iteration …

Improved Attenuation And Crosstalk Modeling Techniques For High-Speed Channels, Shaohui Yong

Doctoral Dissertations

”As digital systems are moving in the direction of faster data transmission rate and higher density of circuits, the problem of the far-end crosstalk (FEXT) and frequency-dependent attenuation are becoming the major factors that limit signal integrity performance. This research is focusing on providing several more comprehensive and accurate modeling approaches for striplines on fabricated printed circuit board (PCB). By characterizing the dielectric permittivity of prepreg and core, dielectric loss tangent, and copper foil surface roughness using measurement data, a better agreement between the stripline model and measurement is achieved. First, a method is proposed to extract dielectric loss tangent …

Analysis And Modeling Of Power Supply Induced Jitter For High Speed Driver And Low Dropout Voltage Regulator, Yin Sun

Doctoral Dissertations

”With the scaling of power supply voltage levels and improving trans-conductance of drivers, the sensitivity of drivers to power supply induced delays has increased. The power supply induced jitter (PSIJ) has become one of the major concerns for high-speed system. In this work, the PSIJ analysis and modeling method are proposed for high speed drivers and the system with on-die low dropout (LDO) voltage regulator. In addition, a jitter-aware target impedance concept is proposed for power distribution network (PDN) design to correlate the PSIJ with PDN parasitic.

The proposed PSIJ analysis model is based on the driver power supply rejection …

Design And Fabrication Of Field-Effect Iii-V Schottky Junction Solar Cells, Amirhossein Ghods

Doctoral Dissertations

“A new concept of field-effect photovoltaic devices with a focus on design and fabrication of single and multi-junction solar cells using III-V materials has been shown and proved. Schottky solar cells based on metal-(insulator)-semiconductor (M-I-S) structure have been designed and fabricated using various wide bandgap semiconductors, such as GaAs and Al_0.3Ga_0.7As. A secondary bias layer has been introduced to the device structure, in which it creates additional band bending and subsequently depletion region at the flat band regions on the top surface of the device. It should be mentioned that the bias layer is designed to …

System Si/Pi Modeling And Analysis, Biyao Zhao

Doctoral Dissertations

"A physics-based circuit modeling methodology for 3D IC/packages is proposed here. The method is based on partial element equivalent circuit (PEEC) and layered Green's function (LGF). The LGFs are calculated from discrete complex image method (DCIM) with three terms, direct coupling, complex images, and surface wave, extracted to analyze the wave behavior. The dominate terms for LGFs are analyzed for four stack-ups in 3D IC/packages. Analytical formulas that include the contribution of complex images are proposed for partial capacitance calculation, with the complex image extracted from LGFs. A chip PDN geometry is used to illustrate the use of LGF in …

Operation And Analysis Of High-Voltage-Gain Dc-Dc Converters With Voltage Multipliers, Mohammad Rashed M. Altimania

Doctoral Dissertations

"This research analyzes and investigates the steady-state operations of four different high-voltage-gain step-up dc- dc converters to achieve a high gain. These topologies consist of a two-phase interleaved boost stage with three various voltage multiplier (VM) stages. The first stage of the first three topologies is the same, which is a two-phase interleaved boost stage implemented by using inductors. The first family used in this research is based on a modified Dickson charge pump voltage multiplier stage, and this family has been studied in discontinuous conduction mode (DCM). The second family relies on a non-inverting or inverting diode-capacitors voltage multiplier …

Strengthening Qc Relaxations Of Optimal Power Flow Problems By Exploiting Various Coordinate Changes, Mohammad Rasoul Narimani

Doctoral Dissertations

"Motivated by the potential for improvements in electric power system economics, this dissertation studies the AC optimal power flow (AC OPF) problem. An AC OPF problem optimizes a specified objective function subject to constraints imposed by both the non-linear power flow equations and engineering limits. The difficulty of an AC OPF problem is strongly connected to its feasible space's characteristics. This dissertation first investigates causes of nonconvexities in AC OPF problems. Understanding typical causes of nonconvexities is helpful for improving AC OPF solution methodologies.

This dissertation next focuses on solution methods for AC OPF problems that are based on convex …

Frequency Selective Surface-Based Sensing: Theory And Applications, Mahboobeh Mahmoodi

Doctoral Dissertations

"Frequency selective surfaces (FSS) are periodic arrays of resonant elements with a specific (resonant) reflection/transmission response when illuminated by electromagnetic energy. FSSs have been utilized for different applications such as spatial filters, reflectors, lenses, radomes, and more recently, as sensors. FSS-based sensors have shown potential for numerous applications in structural health monitoring such as crack detection, concurrent strain and temperature sensing, normal and shear strain sensing, inspection of layered structures, etc. As FSS-based sensing is largely undeveloped, there are many critical aspects that must be fully understood before this sensing approach can be fully utilized. Therefore, the goal of this …

Mesh Networking And Full-Duplex Communication For Wireless Networks, Arul Mathi Maran Chandran

Doctoral Dissertations

“Connectivity with large coverage area; and an increase in spectral efficiency of communications are highly desired features for any wireless network. The presented research work addresses these two feature improvements. First, the work analyzed mesh networks to enhance connectivity for wireless networks. The work analyzed both homogeneous and heterogeneous mesh networks. The work includes the development of an Android application to enable smartphones with multiple interfaces, such as Wi-Fi, Bluetooth, and cellular services, to become convergence devices. These convergence devices are then used to build a heterogeneous mesh network improving connectivity and coverage area. Second, the work explored full-duplex communications, …

Multi-Physics-Based Approach To Active Microwave Thermography, Seyed Ali Mirala

Doctoral Dissertations

“The goal of this work is to advance a novel nondestructive testing (NDT) method for controlled, rapid, and effective inspection of a structure through the integration of microwave NDT and thermography, referred to as Active Microwave Thermography (AMT). In AMT, the structure under test is exposed to microwave radiation and the thermal profile of the structure is monitored via a thermal camera in order to obtain desired information regarding the structure. This new technique is applicable across a wide range of NDT needs including detection of voids, delamination, water ingress, debonding, and cracks in numerous structures such as carbon fiber …

Accurate Modeling Techniques For Power Delivery, Jingdong Sun

Doctoral Dissertations

“Power delivery is essential in electronic systems to provide reliable power from voltage sources to load devices. Driven by the ambitious user demands and technology evolutions, the power delivery design is posed serious challenges. In this work, we focus on modeling two types of power delivery paths: the power distribution network (PDN) and the wireless power transfer (WPT) system.

For the modeling of PDN, a novel pattern-based analytical method is proposed for PCB-level PDN impedance calculations, which constructs an equivalent circuit with one-to-one correspondences to the PCB’s physical structure. A practical modeling methodology is also introduced to optimize the PDN …

Advanced Control Methods On Three-Phase Inverters In Distributed Energy Resources, Sara Yazdani

Doctoral Dissertations

“This research is an endeavor to apply new and well-established control methodologies to improve transient response, stability and reliability of three-phase inverters in grid-connected and isolated mode of operation. In the course of studying the effect of these methodologies, model-based control is introduced and is extensively applied which is relatively a new approach. In addition, the application of this concept has been studied on developing “grid-forming” controls to allow wind and solar inverters to support voltage and frequency levels like traditional generators.

This research encloses the details of three major works of this research and their possible contributions on improving …

Optimal Adaptive Control Of Time-Delay Dynamical Systems With Known And Uncertain Dynamics, Rohollah Moghadam

Doctoral Dissertations

"Delays are found in many industrial pneumatic and hydraulic systems, and as a result, the performance of the overall closed-loop system deteriorates unless they are explicitly accounted. It is also possible that the dynamics of such systems are uncertain. On the other hand, optimal control of time-delay systems in the presence of known and uncertain dynamics by using state and output feedback is of paramount importance. Therefore, in this research, a suite of novel optimal adaptive control (OAC) techniques are undertaken for linear and nonlinear continuous time-delay systems in the presence of uncertain system dynamics using state and/or output feedback. …

Investigation Of Wide Bandgap Semiconductors For Room Temperature Spintronic, And Photovoltaic Applications, Vishal Saravade

Doctoral Dissertations

"Suitability of wide bandgap semiconductors for room temperature (RT) spintronic, and photovoltaic applications is investigated.

Spin properties of metal-organic chemical vapor deposition (MOCVD) – grown gadolinium-doped gallium nitride (GaGdN) are studied and underlying mechanism is identified. GaGdN exhibits Anomalous Hall Effect at room temperature if it contains oxygen or carbon atoms but shows Ordinary Hall Effect in their absence. The mechanism for spin and ferromagnetism in GaGdN is a combination of intrinsic, metallic conduction, and carrier-hopping mechanisms, and is activated by oxygen or carbon centers at interstitial or similar sites. A carrier-related mechanism in MOCVD-grown GaGdN at room temperature makes …

Ferrite Characterization Techniques & Particle Simulations For Semiconductor Devices, Nicholas Erickson

Doctoral Dissertations

"This dissertation is divided into three papers, covering two major topics. The first topic, techniques for ferrite characterization, is discussed over the course of two papers. The second topic, particle simulations for semiconductor devices, is discussed in the last paper. In the first paper, the method for extracting permeability from ferrite materials is discussed for the Keysight 16454A permeability extraction fixture, where the ferrite material to be characterized is assumed to be homogeneous. Then the method is updated to account for layered materials. The updated method is verified through full-wave simulations. In the second paper, a planar printed circuit board …

Modeling Strategies For Estimating And Suppressing Electromagnetic Interference And Improving Power Integrity, Tamar Makharashvili

Doctoral Dissertations

"Decoupling capacitors are used to suppress high-frequency noise in power distribution networks. The inductance associated with a mounted decoupling capacitor can vary by 26% depending on characteristics of the printed circuit board. Here, simple and accurate inductance models of 2- and 8-terminal capacitors including connections to the power and return plane are developed. Circuit models of the capacitors and layout are created using the partial equivalent element circuit method which provide options for circuit-level simulations as well as analytic estimation of inductance. The circuit solution matches results from the full-wave simulation model within 9% for the 8-terminal capacitor and within …

Design And Prototyping Of A Real-Time Millimeter Wave Imaging System, Zahra Manzoor

Doctoral Dissertations

"The goal of this work is to design, prototype and test an innovative millimeter wave imaging system that operates in the frequency range of 33-35 GHz and is capable of producing rapid images of various diverse scenes. In particular, the imaging system includes two main sections, one is related to the hardware design of the system, and the other focuses on the development of a novel comprehensive image reconstruction algorithm. The hardware design includes custom transmitter and receiver sub-systems, and a sparse switched array which was optimized for 320 mm x 220 mm aperture plane, and also included an improved …

Characterization And Modeling Of Esd Events And Near-Field Scanning Calibration Structures, Shubhankar Kashinath Marathe

Doctoral Dissertations

"This research is divided into three papers that cover, two major topics. The first topic, system-level electrostatic discharge (ESD), is discussed over the course of two papers. The second topic, a calibration structure for near-field scanning probe calibration application, is discussed in the last paper. In the first paper, software-assisted detection methods are proposed for secondary ESD discharges. The measured waveforms are analyzed with respect to waveform parameters, such as the vertical threshold of the rising edge, the derivative of the current waveform, and total charge delivered. These parameters enable automatic detection of secondary ESD while monitoring the discharge waveform …

The Tabu Ant Colony Optimizer And Its Application In An Energy Market, David Donald Haynes

Doctoral Dissertations

"A new ant colony optimizer, the 'tabu ant colony optimizer' (TabuACO) is introduced, tested, and applied to a contemporary problem. The TabuACO uses both attractive and repulsive pheromones to speed convergence to a solution. The dual pheromone TabuACO is benchmarked against several other solvers using the traveling salesman problem (TSP), the quadratic assignment problem (QAP), and the Steiner tree problem. In tree-shaped puzzles, the dual pheromone TabuACO was able to demonstrate a significant improvement in performance over a conventional ACO. As the amount of connectedness in the network increased, the dual pheromone TabuACO offered less improvement in performance over the …

2x-Thru, 1x-Reflection, And Thru-Line De-Embedding: Theory, Sensitivity Analysis, And Error Corrections, Bichen Chen

Doctoral Dissertations

"Due to the simplicity of design and measurement, as well as the accuracy of results, the 2X-Thru de-embedding (2XTD), 1X-Reflection de-embedding (1XRD), and Thru-Line de-embedding (TLD) have been replaced the traditional de-embedding algorithms, such as TRL and SOLT. In this dissertation, theory of 2ⁿ-port 2XTD, 1XRD, and TLD are completely derived first. The self-error reduction schemes is introduced to mitigate the de-embedding errors due to non-ideal manufacturing effects of non-zero mode conversion terms, as well as the asymmetric, and manufacturing variations. The validations are performed on both theory and self-error reduction through simulation and measurements cases. The 2X-Thru …

Efficient Estimation And Mitigation For Radio-Frequency Interference, Qiaolei Huang

Doctoral Dissertations

"With rapid innovations in Internet of Things (IoT) and wireless technology, more and more consumer electronic devices around the world are now connected to the internet. In a small form factor electronic device, there are plenty of potential noise sources such as System On Chip (SoC), high speed traces, flexible cables and power converters, etc. Those noise sources can possibly introduce radio frequency interference (RFI) issues. In this dissertation, a transfer function based calculation method is proposed to estimate radio frequency interference (RFI) problems. The derived equations can clearly decompose the RFI problem into two parts: the noise source and …

Passive Harmonic Generation At Spring Contacts, Sen Yang

Doctoral Dissertations

"In the first paper, the RF passive harmonic generation phenomenon on the spring contact is studied. A spring contact harmonic generation measurement system is developed. The factors that may have an impact on the spring contact harmonic generation, such as contact material, contact force, and contact resistance are characterized by the measurement system. The gold-to-gold contact is found to be much superior to the stainless-steel contacts. It is also found that the passive nonlinearity at the spring contact is the semiconductor-like junction formed by the surface oxide film.

In the second paper, we show that the maximum E-field coupling occurs …

Hardware Architectures For Compact Microwave And Millimeter Wave Cameras, Matthew Jared Horst

Doctoral Dissertations

"Millimeter wave SAR imaging has shown promise as an inspection tool for human skin for characterizing burns and skin cancers. However, the current state-of-the-art in microwave camera technology is not yet suited for developing a millimeter wave camera for human skin inspection. Consequently, the objective of this dissertation has been to build the necessary foundation of research to achieve such a millimeter wave camera. First, frequency uncertainty in signals generated by a practical microwave source, which is prone to drift in output frequency, was studied to determine its effect on SAR-generated images. A direct relationship was found between the level …