Engineering Commons^™

Study Of Ultra Wide Band Gap Alxga1-Xn Field Effect Transistors For Power Electronic Applications, Sakib Mohammed Muhtadi

Theses and Dissertations

High Aluminum content Al_xGa_1-xN (x > 30%) has attracted intense research interest nowadays as “Ultra Wide Band Gap (UWBG)” material due to large band gap (> 3.4 eV). The critical electric field (EC) of UWBG semiconductor AlGaN is significantly higher than GaN. Moreover, electron saturation velocity is also comparable to GaN. These attractive material properties are the needs for getting large breakdown voltage and high thermal stability which are the requirements for next generation power semiconductor devices. Theoretical possibilities show UWBG AlGaN based devices are an emerging class and can outperform conventional GaN based devices even at …

Bird's Eye View: Cooperative Exploration By Ugv And Uav, Shannon Hood

Theses and Dissertations

This paper proposes a solution to the problem of cooperative exploration using an Unmanned Ground Vehicle (UGV) and an Unmanned Aerial Vehicle (UAV). More specifically, the UGV navigates through the free space, and the UAV provides enhanced situational awareness via its higher vantage point. The motivating application is search and rescue in a damaged building. A camera atop the UGV is used to track a fiducial tag on the underside of the UAV, allowing the UAV to maintain a fixed pose relative to the UGV. Furthermore, the UAV uses its front facing camera to provide a birds-eye-view to the remote …

Low Bandwidth Communication For Networked Power Hardware-In-The-Loop Simulation, Sean Borgsteede

Theses and Dissertations

Power-Hardware-In-the-Loop (PHIL) simulations allow the design and validation of power hardware components in virtual power system schemas with near real-time operation. This technique is increasingly used in the development cycle of many products to reduce design costs and increase design fidelity. The Hardware under Test (HuT) interfaces with a simulation of the user’s choosing through a hardware interface (HI). The digitally simulated system (DSS) runs on the real-time simulator before sending a reference value to the hardware interface to enforce. In this virtual to real interface, closed-loop stability and the simulation accuracy are the two paramount criteria in regards to …

Dynamic Model And Control Of Quadrotor In The Presence Of Uncertainties, Courage Agho

Theses and Dissertations

This thesis considers the control of quadrotor using a linear PID control and ℒ1 adaptive control. In a justifiable concept, PID controller can be used to control a quadrotor, but in the presence of uncertainties or disturbance, the quadrotor can’t be automatically adjusted to control the changing dynamics of the quadrotor. To solve the problem associated with uncertainties, various control methodology can be used for controlling the changing dynamic of quadrotor, but in this thesis, ℒ1 adaptive control is used because it allows for fast and robust adaptation for desired transient performance in the presence of matched and unmatched uncertainties. …

Physical Characterization Of Electrodeposited Pcb Copper Foil Surfaces, Blessing Kolawole Ojo

Theses and Dissertations

Given that data rates of computers is on the rise and optimization of bus speeds continue to be of importance in improving the system performance, different models for a prediction of the impact of the surface roughness of copper foil have been developed and incorporated into different software’s and applications used by design engineers.

With different models known to have been created for characterization of electrodeposited copper, they have been mostly affected by the need for higher frequencies as they are mostly useful for prediction at frequency of a few GHz. With the introduction of a new model (known as …

Multidisciplinary Shape Optimization Of A Composite Blended Wing Body Aircraft, Charles Maxwell Boozer

Theses and Dissertations

A multidisciplinary shape optimization tool coupling aerodynamics, structure, and performance was developed for battery powered aircraft. Utilizing high-fidelity computational fluid dynamics analysis tools and a structural wing weight tool, coupled based on the multidisciplinary feasible optimization architecture; aircraft geometry is modified in the optimization of the aircraft’s range or endurance. The developed tool is applied to three geometries: a hybrid blended wing body, delta wing UAS, the ONERA M6 wing, and a modified ONERA M6 wing. First, the optimization problem is presented with the objective function, constraints, and design vector. Next, the tool’s architecture and the analysis tools that are …

Cost And Fuel Usage Optimization Of Activating Solution Based Silica Fume Geopolymer Concrete, Lateef Najeh Assi

Theses and Dissertations

Development of sustainable construction materials has been the focus of research efforts worldwide in recent years. Concrete is a major construction material; hence, finding alternatives to ordinary Portland cement is of extreme importance due to high levels of carbon dioxide emissions associated with its manufacturing process. Geopolymer concrete is a potential solution; however, concerns about the high cost and the low real fuel energy efficiency are obstacles against its increase in the market share.

In this thesis, the current cost and fuel (thermal energy) usage are calculated. In addition, the cost and fuel usage were optimized based on previous experimental …

Three Segment Adaptive Power Electronic Compensator For Non-Periodic Currents, Amin Ghaderi

Theses and Dissertations

In this dissertation, a new technique is proposed for the compensation of nonperiodic load current. The method provides control references for three co-located devices, each corresponding to one moving calculation window and one decomposed part of the compensated current. They are slow compensator with high power rating, large calculation window, and low switching frequency; fast compensator with lower power rating, shorter calculation window, and higher switching frequency; and the reactive compensator which is an ordinary static VAR compensator (SVC). To improve the flexibility of the technique, a fuzzy based adaptive window is proposed for the slow compensator to find the …

Wideband Low Side Lobe Aperture Coupled Patch Phased Array Antennas, Dhruva Poduval

Theses and Dissertations

Low profile printed antenna arrays with wide bandwidth, high gain, and low Side Lobe Level (SLL) are in great demand for current and future commercial and military communication systems and radar. Aperture coupled patch antennas have been proposed to obtain wide impedance bandwidths in the past. Aperture coupling is preferred particularly for phased arrays because of their advantage of integration to other active devices and circuits, e.g. phase shifters, power amplifiers, low noise amplifiers, mixers etc. However, when designing such arrays, the interplay between array performance characteristics, such as gain, side lobe level, back lobe level, mutual coupling etc. must …

A Lebesgue Sampling Based Diagnosis And Prognosis Methodology With Application To Lithium-Ion Batteries, Wuzhao Yan

Theses and Dissertations

Fault diagnosis and prognosis (FDP) plays an important role in the modern complex industrial systems to maintain their reliability, safety, and availability. Diagnosis aims to monitor the fault state of the component or the system in real-time. Prognosis refers to the generation of long-term predictions that describe the evolution of a fault and the estimation of the remaining useful life (RUL) of a failing component or subsystem.

Traditional Riemann sampling-based FDP (RS-FDP) takes samples and executes algorithms in periodic time intervals and, in most cases, requires significant computational resources. This makes it difficult or even impossible to implement RS-FDP algorithms …

Fiber Optic Guided Wave Sensors For Structural Health Monitoring, Erik Frankforter

Theses and Dissertations

Risks and costs associated with aging infrastructure have been mounting, presenting a clear need for innovative damage monitoring solutions. One of the more powerful damage monitoring approaches involves using ultrasonic guided waves which propagate through a structure and carry damage-related information to permanently bonded sensors. Ultrasonic fiber-optic sensors are one of the most promising technologies for this application: they are immune to electromagnetic interference, present no ignition hazard, and transmit their data over tens of kilometers. However, before they can be widely employed, several limitations need to be overcome: poor sensitivity, unidirectional sensing, and loss of ultrasonic functionality due to …

Growth And Characterization Of Anisotropic Gase Semiconductor For Radiation Detection And Thz Applications, Haseeb Nazir

Theses and Dissertations

Anisotropic wide-bandgap gallium selenide (GaSe) crystals were grown using high purity (7N) Ga and zone refined (ZR) Se precursor materials. The crystal growth was performed using a modified vertical Bridgman method (VBM) with a slow crystallization from the melt and with a pre-determined temperature profile. The structure, surface morphology, and the composition of the grown crystals were characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive analysis by x-rays (EDAX), respectively. Optical absorption and transmission properties were characterized and optical bandgap was determined. Electrical resistivity has been determined using current-voltage (I V) measurements using van der Pauw …

Structural, Interfacial, And Electrochemical Properties Of Pr2nio4+Δ – Based Electrodes For Solid Oxide Fuel Cells, Emir Dogdibegovic

Theses and Dissertations

Currently, the electrochemical performance and performance durability of solid oxide fuel cells (SOFCs) are limited by cathode materials. The high polarization resistance and phase instability of the cathode are two major challenges to hinder the commercialization of SOFC systems. Two families of oxides are presently known as potential cathode materials for SOFCs: (1) the perovskite family of oxides with a general formula of ABO₃, and (2) the Ruddlesden-Popper (RP) family of oxides (e.g. nickelates) with a general formula of A₂BO₄. The electron-hole conduction in these materials occurs simultaneously with oxygen ion conduction based on …

Far-Field Optical Microscopy Based On Stimulated Emission Depletion, Yunxia Wang

Theses and Dissertations

Conventional lens-based (far-field) fluorescence microscopy is a widely used imaging technique with spatial resolution up to 150–350 nm. However, this technology cannot discern very small structural features, because the spatial resolution is limited by diffraction to about half of the wavelength of light (λ/2，λ is the wavelength of light). Hence, most of the developments in microscopy aim at improving resolution. In the past decades, stimulated emission depletion (STED) microscopy has been developed to bypass the diffraction limit for the application in biological imaging with resolution approaching the nanoscale. The basic principle of STED microscopy is to employ a doughnut-shape laser …

Intermodal Network Design And Expansion For Freight Transportation, Fateme Fotuhiardakani

Theses and Dissertations

Over the last 50 years, international trade has grown considerably, and this growth has strained the global supply chains and their underlying support infrastructures. Consequently, shippers and receivers have to look for more efficient ways to transport their goods. In recent years, intermodal transport is becoming an increasingly attractive alternative to shippers, and this trend is likely to continue as governmental agencies are considering policies to induce a freight modal shift from road to intermodal to alleviate highway congestion and emissions. Intermodal freight transport involves using more than one mode, and thus, it is a more complex transport process. The …

An Application Of Dempster-Shafer Fusion Theory To Lithium-Ion Battery Prognostics And Health Management, John Weddington

Theses and Dissertations

Prognostics and Health Management (PHM) is the discipline involving diagnostics and prognostics of components or systems, with the primary objective of increasing the overall reliability and safety of these components or systems. PHM systems convert raw sensor data into features, and utilize state observers to estimate the current damage state online. Popular state observers are the traditional Kalman filter, along with its non-linear extensions, and the particle filter. Each technique has differing advantages. This thesis investigates the fusion of results from different techniques in order to achieve a more trustworthy probability of detection (PoD) during diagnosis and a more reliable …

Promotional Effect Of Molten Carbonates On Proton Conductivity And Oxygen Reduction Reaction – An Experimental And Computational Study, Xiaolei Xiong

Theses and Dissertations

Recent research of Solid oxide fuel cells (SOFCs) is aimed to lower the operating temperature to an intermediate temperature (IT) range of 500 to 700^oC, while maintaining a proper performance. This Ph.D. research project investigates the promotional effects of alkaline carbonate eutectics on the proton conductivity of proton conducting electrolytes and cathodic ORR reactivity in SOFCs by both experimental and computational methods. The ionic conductivity of the MC-BZY composite above 500^oC increases with the higher loading of MC. The sample exhibited nearly a factor of two higher conductivity in H₂-containing atmosphere than in air. …

High Quality Low Offcut 4h-Sic Epitaxy And Integrated Growth Of Epitaxial Graphene For Hybrid Graphene/Sic Devices, Anusha Balachandran

Theses and Dissertations

Power electronic semiconductor devices are critical components in next-generation power systems such as hybrid electric vehicles and smart grid power controls enabling reduction in system size, weight, and cost. Wide bandgap materials such as SiC, GaN, and diamond have been investigated to replace silicon, due to their superior material properties. Of these, 4H-SiC is considered the most viable candidate beyond 3kV due to its technological maturity, its wide band gap (3.23 eV), high breakdown field (4×106 V/cm), high thermal conductivity (5 W/cm/K) and, more importantly, its indirect bandgap.

The main contribution of my research relates to the development and investigating …

Analysis And Design Of A Highly Compact Ellipse-Shaped Ultra-Wideband Bandpass Filter (Uwb-Bpf) With A Notched Band, Xuetan Liu

Theses and Dissertations

Since the Federal Communications Commission’s endorsement of the frequency band of 3.1 – 10.6 GHz in 2002 to be unlicensed for wireless communication applications, various ultra-wideband bandpass filters (UWB-BPFs) have been proposed and designed. Different UWB-BPF configurations were presented in the past years to meet the very strict UWB-BPF specifications in terms of ultra-band requirement, low return loss, high rejection in notched bands. However, most of the previous works are limited by large dimension size, complex geometry, and high production cost.

The major objective of this work is to design a highly compact, simple geometry, and low-cost UWB-BPF, which passes …

Reducing Model Selection Computational Cost By Metamodeling The Evidence, Ramin Madarshahian

Theses and Dissertations

Modeling is an abstraction of reality that lets a designer or engineer perform simulations with a “real” object or structure without testing it physically. However, the result of simulations is as good as their models. Selecting the best model among many candidates is another challenge.

Complex models could translate into more accurate predictions, but they also require larger computational effort. The Bayes factor is often used to compare different models considering the data and analyst’s experience. To obtain the Bayes factor, the Bayesian model evidence is calculated; however, calculating the Bayesian model evidence of computationally expensive models is not a …

Investigating The Feedstock Properties And Process Conditions Influencing The Characteristics Of Products Generated From The Hydrothermal Carbonization Of Organic Feedstocks, Liang Li

Theses and Dissertations

Hydrothermal carbonization (HTC) is a novel environmentally beneficial thermal conversion process for the transformation of organic feedstocks to value-added products. However, little is known about the role of feedstock properties and/or process conditions during carbonization. This study was conducted to determine the parameters most influential during the HTC of organic feedstocks. Experiments and statistical analyses were conducted to: (1) determine the effect of specific feedstocks, feedstock interactions, and process conditions on carbonization product characteristics; (2) understand how initial liquid characteristics influence product characteristics and evaluate the significance of these initial liquid characteristics in predicting product characteristics; and (3) develop statistical …

Low-Cost Fishing Net-Reinforced Cement Matrix Overlay For Substandard Concrete Masonry In Coastal Areas, Mohammed A. Mousa

Theses and Dissertations

The aim of this project is to investigate a novel and affordable option to externally strengthen substandard concrete masonry (CM) walls for out-of-plane loads (e.g., high winds and flying debris). Two types of strengthening materials for fiber-reinforced cement mortar (FRCM) overlays are investigated; namely, fishing net (FN) and welded wire steel mesh (WWSM) reinforcements.

Salient mechanical properties of representative materials including substandard concrete masonry unit (CMU) blocks, mortar, nylon FN and WWSM reinforcements, and FRCM composite, were experimentally characterized. A simple bilinear model is proposed to describe the tensile behavior of the FRCM composite. An analytical model was then used …

Study Of Mos2 And Graphene-Based Heterojunctions For Electronic And Sensing Applications, Ifat Jahangir

Theses and Dissertations

Since the discovery of graphene, there has been an increase in two-dimensional (2D) materials research for their scalability down to atomic dimensions. Among the analogs of graphene, transition metal dichalcogenides (TMDs) are attractive due to their exceptional electronic and optoelectronic properties. MoS2, a TMD, has several advantages over graphene and the industry workhorse Si, and has been reported to demonstrate excellent transistor performances. The key obstacle in the commercialization of MoS2 technology is low carrier mobility over large areas for top-down devices. Although there were several early reports on synthesis of atomically thin MoS2 with moderate mobility, transferring large area …

Theoretical Investigation Of The Catalytic Hydrodeoxygenation Of Levulinic Acid Over Ru (0001) Catalyst Surface, Osman Mamun

Theses and Dissertations

Due to the rapidly declining fossil fuel reserves and the onset of global climate change, the development of active, selective, and stable catalytic materials for the efficient production of biomass derived platform chemicals, i.e., levulinic acid (LA), succinic acid (SA), γ-valerolactone (GVL) etc., is receiving considerable attention in order to produce second generation biofuels and commodity chemicals. Though solid lignocellulosic biomass is significantly cheaper than petroleum; however, the available technology is the significant barrier for large scale utilization of biomass for the production of biofuels. The development of biomass conversion technology requires, 1) identification of potential biomass chemicals that can …

Distributed Optimization Method For Intelligent Control Of Dc Microgrids, Yuanyuan Fan

Theses and Dissertations

Most of the distributed energy resources, loads and energy storage systems in a DC microgrid are equipped with power electronic converters. With the integration of advanced power electronics devices, a microgrid is able to utilize a broader range of technologies in its design and operation. A key feature of power electronic converter based systems is the ability to direct energy flow within a system with their coordinated operation. A system level control is needed for coordination where converters execute reference points dictated by a system-level control in order to achieve system level goals. System goals can be expressed as a …

Mechanical Characterization And Non-Destructive Evaluation Of Sicf-Sicm Composite Tubing With The Impulse Excitation Technique, Nathaniel Truesdale

Theses and Dissertations

With growing interest on ceramic fiber reinforced ceramic matrix composites (CMC) for accident tolerant fuel, the need for mechanical characterization of ceramic composite arises. It has been of particular interest to non-destructively evaluate the mechanical performance of these composites. Impulse excitation (IE) is a well-established method for non-destructive mechanical characterization of homogeneous isotropic material of well-defined shapes. In this thesis, impulse excitation technique was applied for non-destructive characterization of composite tube for the first time as far as we know. CMC, when stressed beyond its damage threshold, will experience various forms of structural damage, such as matrix micro-cracking, fiber-matrix debonding, …

Determination And Validation Of High-Pressure Equilibrium Adsorption Isotherms Via A Volumetric System, Hind Jihad Kadhim Shabbani

Theses and Dissertations

Adsorption equilibrium isotherms for N2, CO2, and CH4 on zeolite 13X were investigated at three different temperatures (25.5, 50.5 and 75.5 ̊ C) and a pressure range of (0-6.89475) MPa for CH4 and N2 and in the range of (0-4.82633) MPa for CO2 using built in volumetric apparatus. The results were validated using with a volumetric system (ASAP) at the same temperatures and a pressure up to (160-110) KPa respectively. The experimental results were correlated using three process Langmuir (TPLM). The correlated isotherms were then used to calculate the isosteric heat of adsorption for the three gases on 13X. The …

Ultra High-Speed Signaling And Return On Technology Investment (Roti) For The Electrical Interconnects Sector, Azniza Abd Aziz

Theses and Dissertations

Demand for smaller platform sizes with increasing bandwidth has driven crosstalk problems that prevent bus performance to scale with Moore’s Law. Several approaches to reduce crosstalk such as the use of shields, differential links, and equalizers have been rejected due to higher cost and power required to overcome the signal integrity impediments at Gigahertz data rates. Eigen-mode signaling based on modal decomposition techniques is the most recent method to mitigate crosstalk that can potentially satisfy the demand for higher data rates from modern technology industry.

The goal of this research is to allow maximum dense routing between packages on PCBs …

Stilbenes: Therapeutic Interventions Targeting Amyloid Β Protein Aggregation In Alzheimer’S Disease, Yiying Wang

Theses and Dissertations

Alzheimer’s disease (AD) is the most common form of dementia and accounts for 60-80 % of all dementia cases. In the United States, AD is ranked as the 6th leading cause of death and it is the only one among the top 10 that cannot be prevented, treated or even slowed. All FDA approved drugs focus on attenuating the symptoms for a limited time by regulating neurotransmitters without any intervention with the underlying disease process. A major player in the initiation and development of this debilitating disorder is the misfolding and subsequent aggregating of amyloid-β (Aβ) peptide. This aggregation process …

Atherosclerotic Plaque Adhesion Strength And Its Role In Plaque Rupture, Bilal Merei

Theses and Dissertations

Cardiovascular diseases are disorders affecting the blood vessels and the heart. According to the World Health Organization, cardiovascular diseases are one of the leading causes of death worldwide. They are responsible for over 17.1 million deaths per year worldwide, representing 31.5% of deaths 1, 2. Atherosclerosis, a chronic inflammatory disorder affecting large arteries, is the underlying cause of many cardiovascular diseases. Plaque rupture is a serious complication of advanced atherosclerosis, often leading to life-threatening clinical consequences such as myocardial infarction (heart attack) or stroke. 75% of newly developed myocardial infarction cases are caused by atherosclerotic plaque rupture. It affects approximately …