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Hydrodynamics Study Of The Bubble Columns With Intense Vertical Heat-Exchanging Tubes Using Gamma-Ray Computed Tomography And Radioactive Particle Tracking Techniques, Abbas Jawad Sultan

Doctoral Dissertations

"Understanding the hydrodynamics of bubble columns with and without vertical heat-exchanging tubes is a necessity for the proper design, scale-up, and operation of these reactors. To achieve this goal, systematic experiments were performed to visualize and quantify the influence of the presence of vertical internal tubes on the gas holdup distributions and their profiles, axial liquid velocity, and turbulent parameters (i.e., normal and shear stresses; turbulent kinetic energy) by using advanced gamma-ray computed tomography (CT) and radioactive particle tracking (RPT). In this study, the experiments were conducted in 6- and 18-inch bubble columns with an air-water system as the working …

Learning-Based Short-Time Prediction Of Photovoltaic Resources For Pre-Emptive Excursion Cancellation, Huaiqi Xie

Doctoral Dissertations

"There is a growing interest in using renewable energy resources (RES) such as wind, solar, geothermal and biomass in power systems. The main incentives for using renewable energy resources include the growing interest in sustainable and clean generation as well as reduced fuel cost. However, the challenge with using wind and solar resources is their indeterminacy which leads to voltage and frequency excursions. In this dissertation, first, the economic dispatch (ED) problem for a community microgrid is studied which explores a community energy market. As a result of this work, the importance of modeling and predicting renewable resources is understood. …

Machine Learning Techniques Implementation In Power Optimization, Data Processing, And Bio-Medical Applications, Khalid Khairullah Mezied Al-Jabery

Doctoral Dissertations

"The rapid progress and development in machine-learning algorithms becomes a key factor in determining the future of humanity. These algorithms and techniques were utilized to solve a wide spectrum of problems extended from data mining and knowledge discovery to unsupervised learning and optimization. This dissertation consists of two study areas. The first area investigates the use of reinforcement learning and adaptive critic design algorithms in the field of power grid control. The second area in this dissertation, consisting of three papers, focuses on developing and applying clustering algorithms on biomedical data. The first paper presents a novel modelling approach for …

Monitoring Of Hybrid Manufacturing Using Acoustic Emission Sensor, Haythem Gaja

Doctoral Dissertations

"The approach of hybrid manufacturing addressed in this research uses two manufacturing processes, one process builds a metal part using laser metal deposition, and the other process finishes the part using a milling machining. The ability to produce complete functioning parts in a short time with minimal cost and energy consumption has made hybrid manufacturing popular in many industries for parts repair and rapid prototyping. Monitoring of hybrid manufacturing processes has become popular because it increases the quality and accuracy of the parts produced and reduces both costs and production time. The goal of this work is to monitor the …

On Modeling Quantities For Insurer Solvency Against Catastrophe Under Some Markovian Assumptions, Daniel Jefferson Geiger

Doctoral Dissertations

"Insurance companies sometimes face catastrophic losses, yet they must remain solvent enough to meet the legal obligation of covering all claims. Catastrophes can result in large damages to the policyholders, causing the arrival of numerous claims to insurance companies at once. Furthermore, the severity of an event could impact the time until the next occurrence. An insurer needs certain levels of startup capital to meet all claims, and then must have adequate reserves on a continual basis, even more so when catastrophes occur. This work examines two facets of these matters: for an infinite time horizon, we extend and develop …

Mining And Analysis Of Real-World Graphs, Armita Abedijaberi

Doctoral Dissertations

"Networked systems are everywhere - such as the Internet, social networks, biological networks, transportation networks, power grid networks, etc. They can be very large yet enormously complex. They can contain a lot of information, either open and transparent or under the cover and coded. Such real-world systems can be modeled using graphs and be mined and analyzed through the lens of network analysis. Network analysis can be applied in recognition of frequent patterns among the connected components in a large graph, such as social networks, where visual analysis is almost impossible. Frequent patterns illuminate statistically important subgraphs that are usually …

Development And Management Of Advanced Batteries Via Additive Manufacturing And Modeling, Jie Li

Doctoral Dissertations

"The applications of Li-ion batteries require higher energy and power densities, improved safety, and sophisticated battery management systems. To satisfy these demands, as battery performances depend on the network of constituent materials, it is necessary to optimize the electrode structure. Simultaneously, the states of the battery have to be accurately estimated and controlled to maintain a durable condition of the battery system. For those purposes, this research focused on the innovation of 3D electrode via additive manufacturing, and the development of fast and accurate physical based models to predict the battery status for control purposes. Paper I proposed a novel …

Integrated Study On The Applicability Of Co₂-Eor In Unconventional Liquids Rich Reservoirs, Dheiaa Khafief Khashan Alfarge

Doctoral Dissertations

"Unconventional Liquids Rich Reservoirs (ULR) such as Bakken, Niobrara, and Eagle Ford have become the main target for oil and gas investors as conventional formations started to deplete and diminish in number. These unconventional plays have a huge oil reserve; however, the predicted primary oil recovery is still low as an average of 7.5 %. Unconventional Improved Oil Recovery (UIOR) techniques are still a new concept in the oil industry because there is no commercial project for any IOR technique so far. Injecting carbon dioxide (CO₂) might be the most potential strategy to improve oil recovery in such complex plays. …

The Separation Of Shear-Driven Liquid Films From A Sharp Corner, Zahra Sadeghizadeh

Doctoral Dissertations

"The separation of shear-driven liquid films occurs in many engineering applications such as port fuel injected engines, demisters, and gas transfer lines. Despite the importance of this problem, the details of the interaction between operating parameters such as liquid flow rate, gas velocities and liquid film properties on the forces at the expanding corner are still not clear. To enhance the insight on the complicated interaction between the gas and liquid phases, the shear-driven liquid flow around a corner has been studied both experimentally and analytically in this work. The effect of the complex liquid film structure on liquid mass …

The Significance Of Grouping And Missed Bubbles On Interfacial Area Concentration And Void Fraction, Chandller Stephen-Leslie Mills

Doctoral Dissertations

"The two-fluid model is used in nuclear reactor safety codes. Two of the important constitutive relations will be discussed in this study, the interfacial area concentration and void fraction. The Interfacial area concentration is directly affected by the number of bubbles and how these bubbles are categorized into groups. In this study, a new algorithm was implemented to account for trailing bubbles, bubbles with short response times, and the categorization of bubbles based upon diameter for all group 1 bubbles. The optical and conductivity probes were used to determine the void fraction and interfacial area concentration in a bubble column. …

Enhancement Of Heat Transfer Coefficient Using Nanofluids For Multi-Stage Flash Desalination (Msf) Plant, Nasser Zouli

Doctoral Dissertations

“The enhancement of thermal conductivity and local heat transfer coefficient, under laminar and turbulent flow regimes, of water-based spherical Al₂O₃, CuO, and Fe₂O₃ nanofluids have been experimentally investigated for the improvement of the thermal desalination processes using a newly developed sophisticated noninvasive heat transfer coefficient probe that is flush mounted on the inner wall surface of the test section. The nanoparticles have been selected because of their superior thermal conductivity and low cost, as well as the magnetic characteristic of Fe₂O₃ nanoparticle since a magnet can collect it and reuse. …

Detecting Cells And Analyzing Their Behaviors In Microscopy Images Using Deep Neural Networks, Yunxiang Mao

Doctoral Dissertations

"The computer-aided analysis in the medical imaging field has attracted a lot of attention for the past decade. The goal of computer-vision based medical image analysis is to provide automated tools to relieve the burden of human experts such as radiologists and physicians. More specifically, these computer-aided methods are to help identify, classify and quantify patterns in medical images. Recent advances in machine learning, more specifically, in the way of deep learning, have made a big leap to boost the performance of various medical applications. The fundamental core of these advances is exploiting hierarchical feature representations by various deep learning …

Part I: Design, Synthesis, And Studies Of Novel Age-Inhibitors And Age-Breakers; Part Ii: Novel Synthetic Methods For Organofluorine Compound, Jatin Mehta

Doctoral Dissertations

"Novel small molecule inhibitors and breakers of advanced glycation end-products (AGEs) have been synthesized and their in vitro inhibitory activities have been studied by ¹³C NMR, fluorescence, and UV-visible spectroscopy. We have demonstrated that these AGE-inhibitors and AGE-breakers were found to be more effective in their sequestration of AGE intermediates, such as dehydroascorbate (DHA) than the state-of-the art phenacylthiazolium bromide (PTB)-based AGE-inhibitors and AGE-breakers. Citric acid and other polyphenolic antioxidants have substantial AGE inhibitory effects in the D-glucose/leucine or benzylamine Maillard reaction model systems, and thus they are suitable as dietary additives for ameliorating AGE-induced complications.

Organofluorine compounds have …

Bio-Inspired Geomaterial Improvement And Development Of Innovative Characterization Methods, Junnan Cao

Doctoral Dissertations

"This study experimentally investigated the bio-inspired improvement on geomaterials, including enzyme induced calcite precipitation (EICP) and biopolymers. This study also developed several innovative characterization tools to advance the state-of-the-art testing techniques, including SIP-BE column, rotational sedimental panel, and backpressure saturated constant hydraulic gradient break through column. Firstly, EICP test was performed on Ottawa 50-70 sand in a newly developed SIP-BE column. Nondestructive techniques -- spectral induced polarization (SIP) and bender element were used to monitor the precipitation process and shear wave velocities (V_s). SIP, V_s, and SEM results all suggest contact cementation as the preferential precipitation …

Nanoporous Carbon Scaffolds For Energy Storage Applications, Waruni Jayawardana

Doctoral Dissertations

"Nanoporous carbons (NCs) have become increasingly popular in various fields of research due to their unique properties including tunable pore sizes, higher pore volumes and higher surface areas, as well as being able to produce controlled nanostructures. The work presented here uses NC scaffolds with as active hosts for (1) Li-ion battery electrodes and (2) confined metal hydrides (MH) for hydrogen storage applications. In (1) we investigate the Li diffusion characteristics in hard carbons (HCs) that are important for electrochemical applications. We develop a novel method named Voltage-Relaxation Galvanostatic Intermittent Titration Technique (VR-GITT). Parameters derived from the fitting of electrochemical …

A Methodology To Predict Community College Stem Student Retention And Completion, Jennifer Lynn Snyder

Doctoral Dissertations

"Numerous government reports point to the multifaceted issues facing the country's capacity to increase the number of STEM majors, while also diversifying the workforce. Community colleges are uniquely positioned as integral partners in the higher education ecosystem. These institutions serve as an access point to opportunity for many students, especially underrepresented minorities and women. Community colleges should serve as a major pathway to students pursuing STEM degrees; however student retention and completion rates are dismally low. Therefore, there is a need to predict STEM student success and provide interventions when factors indicate potential failure. This enables educational institutions to better …

Cappack Devices For The Evaluation Of Parameters And Pulse Performances In Liquid And Solid-State Nmr Spectroscopy, Lingyu Chi

Doctoral Dissertations

"NMR spectroscopy is a powerful analytical tool to obtain explicit information about molecular structures, conformations, dynamics, and functions. To extract the desired information most accurately, NMR reference standards and devices are needed for calibrating the spectrometer hardware, generating reference data for the NMR software, and testing the applicability of pulse sequences. In this dissertation, the CapPack (Capillary-tube Package) platform is introduced which provides well-defined external reference and calibration standards for liquid and solid-state NMR applications. CapPacks consist of one or more permanently sealed capillary tubes that, depending on the intended application, come arranged in different geometries such as side-by-side or …

Design And Development Of A Compact X-Ray Tube For Stationary Ct Architecture, Ashish Vighnahar Avachat

Doctoral Dissertations

"Multisource architectures enable sweeping one or more x-ray beams across the imaging field-of-view faster than physically moving a single x-ray source and/or a detector. Hence, these architectures are attractive for the applications in which temporal resolution plays an important role, for example, cardiac computed tomography (CT) or real-time CT. One of the recent developments in multisource architectures for CT imaging is stationary CT architecture, whereby two separate stationary arrays -- one for x-ray sources and one for detectors -- are utilized to sweep one or more x-ray beams along the gantry and acquire 360 degree projections. To have a stationary …

Modeling And Experimental Investigations On Particle Dynamic Behaviors In Laser 3d Printing With Blown Powder, Wei Li

Doctoral Dissertations

"Pre-mixed powder is frequently-used powder supply to fabricate Functional Gradient Material (FGM) by Laser 3D printing, which is also called Laser Metal Deposition (LMD). The deposited FGM composition is expected to be similar or same as supplied powder mixture. However, because pre-mixed powder has different particle densities and particle sizes, the caused particle acceleration differences can result in the separation in powder mixture. Up to now, there was no study focused on pre-mixed powders' flow behavior in LMD. The current research aims to investigate the flow behaviors of pre-mixed powder supplied for LMD through both experimental and modeling approaches. In …

Seismic Anisotropy And The Mantle Dynamics Beneath The Arabian Plate, Saleh Ismail Hassan Qaysi

Doctoral Dissertations

"We investigate mantle seismic azimuthal anisotropy and deformation beneath the Arabian Plate and adjacent areas using data from 182 broadband seismic stations which include 157 stations managed by the Saudi Geological Survey. A total of about 4000 pairs of shear wave splitting parameters are obtained using the transverse minimization technique. The individual XKS (including PKS, SKS, and SKKS) splitting measurements were manually checked to ensure the quality. The well-defined parameters show dominantly N-S fast orientations at the majority of the stations, and NW-SE fast orientations along the Zagras Mountain front. No clear systematic variations of the splitting parameters as a …

Correlation Between Delay Time And Measured Concentration And Concentration Uncertainty By Neutron Activation Analysis, James Thomas Seman

Doctoral Dissertations

"For the last several decades, it has been apparent that new methods of identifying explosives can help investigators trace their origins. One way to identify an explosive is through the use of taggants: materials added to a product that encodes information about the product such as when it was manufactured.

This research investigates the survivability of a new identification taggant called the Nuclear Barcode that overcomes some of the downfalls that have been identified in prior taggants. The Nuclear Barcode encodes information as a unique combination of concentrations of rare earths (Ho, Eu, Sm, Lu, and Dy) and precious metals …

Phenolic Resin Aerogels: The Significance Of Inserting An Oxidative Ring-Fusion Aromatization Step At The Early Stages Of Pyrolytic Carbonization, And The Application Of These Materials In Co₂ Storage And Separation, Hojat Majedi Far

Doctoral Dissertations

"Phenolic aerogels, prepared via polycondensation of phenolic monomers and formaldehyde, were converted to carbon aerogels at 800 ⁰C/Ar followed by reactive etching under flowing CO₂. Previously, it was found that a lower-temperature air-oxidation of polybenzoxazine aerogels was necessary in order to obtain highly porous, isomorphic carbon aerogels with high carbonization yields. Using those findings as the point of departure, phenolic aerogels were oxidized at 240 ⁰C/air prior to carbonization. During that air-oxidation step, phenolic aerogels based on phloroglucinol (1,3,5- trihydroxybenzene) undergo fusion of their aromatic rings, yielding 6-membered heteroaromatic pyryliums with pendant phenoxide ions. The resulting carbon aerogels …

Signal Processing For Microwave Imaging Systems With Very Sparse Array, Xiahan Yang

Doctoral Dissertations

"This dissertation investigates image reconstruction algorithms for near-field, two dimensional (2D) synthetic aperture radar (SAR) using compressed sensing (CS) based methods. In conventional SAR imaging systems, acquiring higher-quality images requires longer measuring time and/or more elements in an antenna array. Millimeter wave imaging systems using evenly-spaced antenna arrays also have spatial resolution constraints due to the large size of the antennas. This dissertation applies the CS principle to a bistatic antenna array that consists of separate transmitter and receiver subarrays very sparsely and non-uniformly distributed on a 2D plane. One pair of transmitter and receiver elements is turned on at …

Direct Numerical Simulation Of Pressure Fluctuations Induced By Supersonic Turbulent Boundary Layers, Chao Zhang

Doctoral Dissertations

"Direct Numerical Simulations are used to generate a database of high-speed zero-pressure-gradient turbulent boundary layers developing spatially over a flat plate with nominal freestream Mach number ranging from 2:5 to 14 and wall-to-recovery temperature ranging from 0:18 to 1:0. The flow conditions of the DNS are representative of the operational conditions of the Purdue Mach 6 quiet tunnel, the Sandia Hypersonic Wind Tunnel at Mach 8, and the AEDC Hypervelocity Tunnel No. 9 at Mach 14. The DNS database is used to gauge the performance of compressibility transformations, including the classical Morkovin's scaling and strong Reynolds analogy as well as …

Characterization Of The Cylinderical Split Internal-Loop Photobioreactor With Scenedesmus Microalgae: Advanced Culturing, Modeling, And Hydrodynamics, Laith S. Sabri

Doctoral Dissertations

"Microalgae are fast growing photoynthetic microorganisms and it have very wide range of industrial applications such as biofuels and wastewater treatment. These cells can be grown in a wide variety of systems ranging from open culture systems (e.g., ponds) to closed culture systems of photobioreactor (e.g., airlift). The open culture systems exist in the external environment, and hence, are not intrinsically controllable. However, the microalgae production in enclosed photobioreactors faces prohibitively high production costs with special difficulty in reactor design and scale-up. The light availability and utilization efficiency in the photobioreactor in terms of design and scale-up consider as the …

Dragline Excavation Simulation, Real-Time Terrain Recognition And Object Detection, Godfred Somua-Gyimah

Doctoral Dissertations

"The contribution of coal to global energy is expected to remain above 30% through 2030. Draglines are the preferred excavation equipment in most surface coal mines. Recently, studies toward dragline excavation efficiency have focused on two specific areas. The first area is dragline bucket studies, where the goal is to develop new designs which perform better than conventional buckets. Drawbacks in the current approach include operator inconsistencies and the inability to physically test every proposed design. Previous simulation models used Distinct Element Methods (DEM) but they over-predict excavation forces by 300% to 500%. In this study, a DEM-based simulation model …

Empirical Correlations Between Rock Cutting Parameters And Excavated Rock Surface Rebound Hardness, Azupuri Germanus Ayerikujei Kaba

Doctoral Dissertations

"In field excavation, cutting tools operate on rock surfaces damaged from previous tool pass, yet, average intact rock properties are often used in field project estimations. This can result in overestimation of excavation time and cost. The ability to accurately correlate the damaged rock properties to the excavation parameters means more reliable estimates of project completion time and costs, and hence improved the application of mechanical excavation technology to a wider range of civil and mining industries.

The purpose of this research was to better understand the relationship between rock cutting parameters and the excavated rock surface hardness during mechanical …

Delineation Of A Coal Combustion Residue Landfill And Underlying Karst Subsurface In Southwest Missouri Using Ert And Masw Surveys, Ruobai Zhao

Doctoral Dissertations

"The safe containment of coal combustion residual (CCR) in landfills was addressed by the U.S. Environment Protection Agency (EPA) CCR rule published in 2015. The new rule affects new and existing U.S. based CCR landfills in terms of implementing safeguard systems for safe disposal and contamination control. Electrical resistivity tomography (ERT) and multichannel analysis of surface waves (MASW) data were acquired across and in proximity to a CCR landfill in southwest Missouri, USA, with the intent to identify potential karst features and seepage pathways.

Electrical resistivity tomography data were acquired using an automated 8-channel resistivity meter and multichannel analysis of …

A Proactive Drilling System To Prevent Stuck Pipe And Differential Sticking, Ethar H. K. Alkamil

Doctoral Dissertations

"During drilling operations for the E oilfield in the Mishrif formation in southern Iraq, stuck pipe and differential sticking have been identified as significant geomechanical and drilling problems for several deviated wells. In this work, an integrated approach with three phases is presented to serve as a proactive geo-drilling system to prevent wellbore instability. In the first phase, a comprehensive geomechanical assessment of the Mishrif formation has been carried out to evaluate the in-situ stresses, maximum horizontal stress orientation, pore pressure, rock properties, and rock strength parameters. Moreover, the geomechanical evaluation has been incorporated into the mud design using three …

Soy-Based Polyurethane Foam For Insulation And Structural Applications, Gurjot S. Dhaliwal

Doctoral Dissertations

"Polyurethane (PU) foams are widely used as insulation materials due to their high insulation properties and low cost compared to conventional materials such as styrene and mineral wool. PU foams are traditionally fabricated with petroleum-based precursors. However, high crude price and higher carbon footprint has lead interest of researchers to synthesis PU foams using plant-based raw materials, that are inexpensive and renewable. In this dissertation, PU foams were fabricated using soy-based polyol and its thermal and mechanical properties were investigated. In the first part, of PU foam samples with different formulations were fabricated using soy-based polyol HB230, and varying amounts …