Engineering Commons^™

Stability Analysis Of Microgrids Using Markov Jump Linear Systems, Gilles Mpembele

Doctoral Dissertations

"This research discusses stochastic models for a microgrid operating between standalone and grid-tied modes. The transitions between different modes are modeled as a continuous-time Markov chain (CTMC). In each operating mode, the system is modeled using conventional differential algebraic equations (DAEs), linearized around some equilibrium point.

In Topic-I, a model is developed using the Stochastic Hybrid Systems (SHSs) formulation. The microgrid is modeled as a Markov jump linear system (MJLS), which is a type of SHS in which the discrete events evolve according to a Continuous Time Markov Chain (CTMC). The model allows for the derivation of Ordinary Differential Equations …

Scheduling Based Optimization In Software Defined Radio And Wireless Networks, Nathan Daniel Price

Doctoral Dissertations

"The objective of this work is to enable dynamic sharing of software-defined radio (SDR) transceivers through the concepts of hardware virtualization and real-time resource management. SDR is a way to build a digital radio that consists of a software back-end for digital signal processing (DSP) and an analog front-end transceiver for waveform generation and reception. This work proposes the use of a virtualization layer to decouple back-end SDR software from front-end transceivers. With this arrangement, front-ends are said to be virtualized, and it becomes possible to share a limited number of front-ends among many SDR back-ends through different multiplexing techniques. …

Investigation Of Packed Bed And Moving Bed Reactors With Benchmarking Using Advanced Measurement And Computational Techniques, Binbin Qi

Doctoral Dissertations

"Trickle bed reactors (TBR), as typical packed bed reactors (PBR), are widely used in various fields. Very limited information regarding the flow behaviors, hydrodynamic, and mathematical models in extrudate catalyst shapes, such as cylinders, trilobes, and quadrilobes, can be found in literatures because the major focus was on spherical shape. Therefore, a hybrid pressure drops and liquid holdup phenomenological model for extrudate catalyst shapes was developed based on two-phase volume averaged equations, which showed high accuracy against experimental data. The maldistribution and dynamic liquid holdup were investigated in quadrilobe catalyst using gamma-ray computed tomography. A pseudo-3D empirical model was developed …

Source Reconstruction In Near Field Scanning For Rfi Application, Hosseien Rezaei

Doctoral Dissertations

"This research is divided into three major topics. The first topic, mechanical magnetic field generator for communication in the ULF range, is discussed in the first paper. The second topic, source reconstruction in near field scanning for RFI application, is discussed over the course of two papers. The third topic, analysis of imbalanced 2 or 3 Wire VHF LISN, is discussed in the last two papers.

In the first topic, the possibility to use a mechanical system (a rotating magnet) as a source (generator or antenna combined) of the ULF magnetic field is investigated. Ultralow frequency (ULF) communication systems have …

Modeling And Analyzing Parasitic Parameters In High Frequency Converters, Mohamad Saleh Sanjari Nia

Doctoral Dissertations

"This research focuses on electromagnetic interference (EMI) / electromagnetic compatibility (EMC) design and analysis in power electronics systems. To limit the EMI under the standards, different methods and strategies are investigated. Parasitic parameters of high frequency (HF) transformer are analyzed using a novel analytical method, finite element method (FEM), and experimental measurements for different structures and windings arrangements. Also, the magnetic field, electric field, electric displacement, and electric potential distribution are simulated and analyzed. Moreover, a high voltage system is considered and analyzed to improve the EMC. The EMI propagation paths are analyzed. The EMI noise level of the system …

Thermophysical Properties Of Nominally Phase Pure Boride Ceramics, Austin D. Stanfield

Doctoral Dissertations

"This research focusses on the thermophysical properties of nominally phase pure boride ceramics. As interest in ultra high temperature ceramics increases due to a renewed interest in hypersonic flight vehicles and with the expanding materials design space accompanying interest in high entropy materials, it is imperative to understand the intrinsic properties of boride ceramics. By reducing Hf content in ZrB₂ from the natural abundance, ~1.75 at% in this case, to ~100 ppm, thermal conductivity increased from 88 W/m·K to 141 W/m·K. Removal of Hf allowed the thermal conductivity of ZrB₂ with small transition metal solute additions to be …

Pdn Modeling For High-Speed Multilayer Pcb Boards And Decap Optimization Using Machine Learning Techniques, Ling Zhang

Doctoral Dissertations

"In power distribution networks (PDN), there are two main challenges nowadays. One challenge is how to efficiently model and calculate the impedance for arbitrary-shape and multi-layer PDN systems. The second challenge is the optimization of decoupling capacitors in the pre-layout stage. This dissertation proposes novel solutions to these two challenges. To tackle the first challenge, a boundary element method (BEM) is utilized to calculate the quasi-static inductances between vertical vias for arbitrary-shape planes. Then a specialized circuit solver is developed to solve the equivalent circuit of inductances and capacitances for multi-layer PDN structures. Also, a contour integral method (CIM) is …

Quantum Inspired Concepts In Decision Making, Qizi Zhang

Doctoral Dissertations

"In this study, several new applications of quantum-inspired techniques are presented to advance the state of the art in decision making. In the first part, a quantum boost scheme for multiple-model filters based on extended Grover’s algorithm is presented for fault detection and parameter estimation. The quantum boost scheme accelerates the convergence of the posterior probabilities in the multiple-model filter. Stability proofs for the quantum boost scheme is presented and its performance is analyzed using benchmark examples. In the second part, the scope of application is extended to modeling human decision making. The open quantum system cognition model is applied …

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 …

Infrastructure Systems Modeling Using Data Visualization And Trend Extraction, Jacob Marshal Hale

Doctoral Dissertations

“Current infrastructure systems modeling literature lacks frameworks that integrate data visualization and trend extraction needed for complex systems decision making and planning. Critical infrastructures such as transportation and energy systems contain interdependencies that cannot be properly characterized without considering data visualization and trend extraction.

This dissertation presents two case analyses to showcase the effectiveness and improvements that can be made using these techniques. Case one examines flood management and mitigation of disruption impacts using geospatial characteristics as part of data visualization. Case two incorporates trend analysis and sustainability assessment into energy portfolio transitions.

Four distinct contributions are made in this …

Scaling, Experiments, And Simulations Of Condensation Heat Transfer For Advanced Nuclear Reactors Safety, Palash Kumar Bhowmik

Doctoral Dissertations

“The purpose of this research was to perform scaled experiments and simulations to validate computational fluid dynamics (CFD) and empirical models of condensation heat transfer (CHT) for the passive containment cooling system (PCCS) of Small Modular Reactors (SMRs). SMRs are the futuristic candidates for clean, economic, and safe energy generation; however, reactor licensing requires safety system evaluations, such as PCCS. The knowledge in the reviewed relevant literature showed a gap in experimental data for scaling SMR’s safety systems and validating computational models. The previously available test data were inconsistent due to unscaled geometric and varying physics conditions. These inconsistencies lead …

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 …

Gis And Remote Sensing Groundwater Potentiality Investigation Of Gulu District, Uganda Using Synthetic Aperture Radar And Magnetic Geophysics, Rachel Ann Jones

Doctoral Dissertations

“Developing countries have few resources for ground-based hydrological investigations to determine optimal placement of boreholes for community water access. Remote sensing data are available at a variety of resolutions and sense different parameters, and are useful inputs for hydrologic models, but these data are rarely obtainable in developing countries with the parameters or resolutions necessary for hydrologic applications. This research seeks to use and improve existing remote sensing and GIS techniques to identify areas of optimal water supply in locations with limited geologic or hydrologic information, such as Gulu District, Uganda. Fusing different remotely sensed data sets can produce higher …

Innovative Modeling And Management Of Infrastructure Systems, Engineering And Construction Operations, And Offsite Construction Technology Using Computational Data Analytics, Rayan Hassane Assaad

Doctoral Dissertations

“The construction industry has been facing considerable challenges due to the inadequacy of the traditional methods in executing, managing, and modeling infrastructure and construction projects. While many techniques have been developed to improve the decision-making process in the industry, there is no evidence of sufficient and continuous improvements in the industry’s adoption and implementation of innovative techniques such as new management approaches, modern modeling methods, and emerging computational data analytics. To this end, the goal of this research is to address some of the recent challenges faced in the industry with a focus on infrastructure asset management, construction engineering and …

Contributions To The Performance Of Thin Film Capacitors For High Reliability Applications, Daniel Krueger

Doctoral Dissertations

"Capacitors are critical devices in microelectronic assemblies that must be incorporated into electronic systems through a variety of ways such as integrated or discrete devices. This work has developed new thin film capacitors deposited directly onto multichip module or printed circuit board surfaces to benefit from closer integration that enhances system performance for use in high reliability applications. The capacitors serve as filters or provide tuning and energy storage functions. Unexpected performance was observed during development that included low adhesion of the films to the substrates, higher effective dielectric constants than reported in literature, and low yields. Three publications resulted …

Studies On Protein Solubility, Ke Li

Doctoral Dissertations

"Solubility is a critical factor of protein-based drugs during processing and patient administration. This study focused on two aspects of solubility: one was the poly (ethylene) glycol (PEG) precipitation of monoclonal antibodies (mAbs) and another was crystallins aggregation that is associated with cataracts. Protein precipitation by PEG is a common technique for downstream processing. The effects of pH, ionic strength and the exclude volume effect on the protein precipitation by PEG were extensively studied, but the effects of glycosylation on protein precipitation by PEG has not been examined. Protein aggregation is not only a problem in downstream processing, but it …

Numerical And Experimental Study Of Mechanical Properties For Laser Metal Deposition (Lmd) Process Part, Lan Li

Doctoral Dissertations

"Laser Metal Deposition (LMD), also called as, Laser Engineered Net Shaping (LENS), Directed Energy Deposition (DED), is a typical Additive Manufacturing (AM) technology, is used for advanced free-form fabrication. It creates parts by directly melting materials and depositing them on the workpiece layer by layer. In this process, the metal powder or fiber is melted within the melting pool by laser beam or electron beam and quickly solidifies to the deposited layer. LMD technology shows great advantages over traditional manufacturing on complex structure fabrication, including high building rates, easy material replacement and reduced material waste. These merits make the wide …

Reveal Wind Loading Of Tornadoes And Hurricanes On Civil Structures Towards Hazard-Resistant Design, Ryan Honerkamp

Doctoral Dissertations

"Extreme winds impacting civil structures lead to death and destruction in all regions of the world. Specifically, tornadoes and hurricanes impact communities with severe devastation. On average, 1200 tornadoes occur in the United States every year. Tornadoes occur predominantly in the Central and Southeastern United States, accounting for an annual $1 billion in economic losses, 1500 injuries, and 90 deaths. The Joplin, MO Tornado in 2011 killed 161 people, injured more than 1000, destroyed more than 8000 structures, and caused $2.8 billion of property loss. Hurricanes occur predominantly on the United States East coast regions and along the coast of …

Multi-Fidelity Modeling For Aerothermal Analysis Of Deployable Planetary Entry Technologies, Mario J. Santos

Doctoral Dissertations

“NASA is developing deployable entry technologies in the form of the Hypersonic Inflatable Aerodynamic Decelerator (HIAD) and the Adaptable Deployable Entry Technology (ADEPT) vehicles to support human exploration of Mars. To ensure that these technologies are reliable under uncertain entry conditions and extreme aerothermal environments, uncertainty quantification must be integrated into the design process which typically requires large number of high-fidelity computational fluid dynamics (CFD) simulations with prohibitively high computational cost. To address this challenge, construction of multi-fidelity aerothermal response predictions which combine low-fidelity correlations with fewer high-fidelity CFD models in a way that produces highly accurate surrogates with reduced …

Effect Of Radiation Damage On Organic Phase Change Materials Thermal Storage Properties, Ryan Phillip Steere

Doctoral Dissertations

"This work discusses the effects of radiation damage on organic phase change materials for use in nuclear reactor containments and space craft. The effects of radiation on the latent heat of polyethylene wax (PEW) and a eutectic of methyl palmitate and lauric acid (EMPaLA) are evaluated. These PCMs were irradiated in three locations: the Missouri University of Science and Technology research reactor (MSTR), the University of Missouri research reactor (MURR) and cyclotron (MUC) up to a total dose of 2826, 2895 and 662 Gy, respectively. The samples irradiated at the MSTR showed latent heat changes up to 15.5% lower than …

Using Similitude Theory And Discrete Element Modeling To Understand The Effects Of Digging Parameters On Excavation Performance For Rubber Tire Loaders, Atta Ur Rehman

Doctoral Dissertations

"The large sizes of mining equipment pose challenges for analysis using experiments or simulation. While scaled physical and simulation models can address this challenge, no previous work has explored how similitude theory and modeling can provide valid analysis of large equipment such as rubber tire loaders. The objective of this research was to apply similitude theory and discrete element modeling (DEM) to study the effect of different digging parameters on the penetration and the draft on the buckets of rubber tire loaders. The work sought to (1) test the hypothesis that the geometry of a rubber tire loader bucket and …

Enhanced Heavy Oil Recovery By Low Salinity Polymer Flood Combined With Microgel Treatment, Yang Zhao

Doctoral Dissertations

“Heavy oil resources account for a large portion of the total oil reserves around the world. The target heavy oil reservoir is located on Alaska’s North Slope (ANS). Advantages of low-salinity HPAM polymer (LSP) over high-salinity polymer (HSP) were demonstrated. LSP could recover more oil with 40% less polymer consumption. No additional oil was recovered by HSP after LSP flood. The first-ever polymer flood pilot on ANS showed remarkable success regarding water cut reduction, oil production increase, delayed breakthrough, and projected oil recovery improvement. Polymer alone was insufficient to achieve satisfactory recovery as the reservoirs were highly heterogeneous. Microgels could …

Sensor Data Based Adaptive Models For Assembly Worker Training In Cyber Manufacturing, Md. Al-Amin

Doctoral Dissertations

“Production innovations are occurring faster than ever leading conventional production systems towards cyber manufacturing. Manufacturing workers thus need to frequently learn new methods and skills. In fast-changing, largely uncertain production systems, manufacturers with the ability to comprehend workers’ behavior and assess their operational performance in near real-time will achieve better performance than peers. Recognizing worker actions in near real-time while performing the assembly can serve this purpose. However, reliably recognizing the assembly actions performed by the workers is challenging, because the actions for assembly are complex and workers are not only heterogeneous but sensitive to the variation of the work …

Semi-Empirical Modeling Of Liquid Carbon's Containerless Solidification, Philip C. Chrostoski

Doctoral Dissertations

“Elemental carbon has important structural diversity, ranging from nanotubes through graphite to diamond. Previous studies of micron-size core/rim carbon spheres extracted from primitive meteorites suggest they formed around such stars via the solidification of condensed carbon-vapor droplets, followed by gas-to-solid carbon coating to form the graphite rims. Similar core/rim particles result from the slow cooling of carbon vapor in the lab. The long-range carbon bond-order potential was used to computationally study liquid-like carbon in (1.8 g/cm³) periodic boundary (tiled-cube supercell) and containerless (isolated cluster) settings. Relaxations via conjugate-gradient and simulated-annealing nucleation and growth simulations using molecular dynamics were …

Mining Haul Road Defect Detection -- Advancement In Automated Road Extent And Response Calibration For Improved Maintenance, Alexander David Douglas

Doctoral Dissertations

Mine haul roads degrade rapidly due to extremely heavy loads on sub optimal construction materials. This research tests two methods of defect detection to determine limitations to current technology: optical detection and vehicle vibration response. Optical defect detection was found to have the least significant limitations for surface defect detection and vehicle vibration response modeling has the least significant limitations for subsurface defects. This research proposes novel methods to eliminate the critical limitations of both technologies.

Unmanned Aerial Vehicles (UAV) equipped with GPS and a high-resolution camera is used to create a 3-D point cloud using a structure-from-motion algorithm. This …

Catalytic Carbon Dioxide Hydrogenation To Methanol/Dimethyl Ether Over Copper-Based Catalysts, Xiao Fan

Doctoral Dissertations

Direct synthesis of dimethyl ether (DME) via CO₂ hydrogenation has received great attention, owing to the global warming caused by CO₂ emission and increasing energy demand worldwide. In this works, three major aspects of bifunctional catalysts development were studied: (1) investigation of the roles of interaction in the CuO-ZnO-ZrO₂-Al₂O₃/HZSM-5 bifunctional catalysts, (2) deactivation and regeneration of CuO-ZnO-ZrO₂-Al₂O₃ with different zeolitic catalysts for one-step CO₂ hydrogenation to dimethyl ether, and (3) study on the enhancement of activity and stability of CZZA/HZSM-5 bifunctional catalysts via the introduction of …

Use Of Portable Seismic Property Analyzer And Ground Penetrating Radar To Assess Bridge Decks, Samie Ramadan A Hamad

Doctoral Dissertations

The Montauk Bridge deck was assessed based on the portable seismic property analyzer and ground penetrating radar data. Based on the analysis of the portable seismic property analyzer data, it was determined that over 65% of bridge conditions were rated serious to poor condition with an average compressive strength of less than 2500 psi; less than 35% of bridge deck conditions were rated fair to good with an average compressive strength over 2500 psi. Based on ground penetrating radar data, it was determined that 72% of the bridge deck was in serious to poor condition, and only 28% of the …

Relating Detonation Parameters To The Detonation Synthesis Of Nanomaterials, Martin Langenderfer

Doctoral Dissertations

“This research investigates the physical and chemical processes that contribute to the detonation synthesis of silicon carbide nanoparticles. Bulk production of SiC nanoparticles through detonation is possible due to pressures achieved over 20 GPa and temperatures over 2000 K as well as quenching rates in excess of 13 billion K/second. These conditions catalyze reaction and bottom-up molecular growth while retaining particles < 100 nm in diameter. In this work, detonation synthesis of SiC was demonstrated by incorporation of polycarbosilane, an SiC precursor material, into an RDX/TNT explosive matrix prior to detonation. Detonation Synthesis of SiC was also accomplished by reacting elemental silicon with carbon liberated by the detonation of negatively oxygen balanced TNT. Hydrodynamic simulation of a 60:40 mass ratio RDX/TNT detonation created conditions thermodynamically suitable to produce cubic silicon carbide within the first 500 nanoseconds after the passage of the detonation wave while carbon remains chemically reactive for molecular formation. Simulations and experimental tests indicated that loading configuration and impedance mismatch of the precursor additives used in detonation synthesis results in conditions in the additives that exceed the accepted detonation pressure of the explosive by greater than three times. Finally, a full factorial experimental design showed increasing silicon concentration, reducing silicon size, and reducing oxygen balance by adjusting the ratio of RDX to TNT decreased the explosives detonation pressure by 20% and increased the soot yield and concentration of SiC observed in the detonation products by 82% and 442% respectively”--Abstract, page iv.

Dynamic Behavior And Interactions Of Ferrofluid Droplets Under Magnetic Fields In Low Reynolds Number Flows, Md Rifat Hassan

Doctoral Dissertations

Digital microfluidics in combination with emulsion microfluidics are crucial building blocks of droplet-based microfluidics, which are prevalent in a wide variety of industrial and biomedical applications, including polymer processing, food production, drug delivery, inkjet printing, and cell-based assays. Therefore, understanding the dynamics and interactions of droplets as well as the interactions between the droplets and solid surfaces are of great importance in order to improve the performance or product in these applications.

Recently, several studies in the literature have demonstrated the potential of magnetic fields in controlling the behavior of droplets in microscale; however, the fundamental mechanism behind the interesting …