Digital Commons Network^™

Synthesis And Comprehensive Studies Of Nanogels For Enhanced Oil Recovery, Jiaming Geng

Doctoral Dissertations

“Nanomaterials have been developed and applied for enhanced oil recovery (EOR) in oil industry. Among the developed nanomaterials, nano-sized crosslinked polymeric gel particles (nanogels) have shown the potential in improving both the macro- and micro-displacing efficiency. This dissertation focuses on the synthesis and the potential EOR mechanisms of nanogels. Nanogels with positive, negative, and neutral charges were synthesized through suspension polymerization. The morphology, size distribution, and zeta potential of nanogels were elucidated by corresponding technologies, such as scanning electron microscopy and dynamic light scattering. The ability of nanogels in oil-water interfacial tension (IFT) reduction and oil-in-water (o/w) emulsion stabilization was …

Shear Performance And Behavior Of Long Carbon Fiber Reinforced Concrete, Benjamin Paul Gliha

Doctoral Dissertations

”In this study, a laboratory testing program was developed to investigate the shear performance of fiber reinforced concrete beams. Long carbon fibers, to be included with a traditional fresh concrete mix, were developed and their shear performance was evaluated and compared to the performance and behavior of unreinforced concrete, traditionally reinforced concrete, and fiber reinforced concrete (FRC) with other fiber types.

The experimental program consisted of 30 large-scale beams tested for shear performance under monotonic loading. In addition to the large-scale beams, small-scale specimens were constructed of the same materials to correlate large-scale performances to ASTM C1609 testing and to …

Engineering Polymeric Hollow Fiber Membrane Reactors For Sustainable Chemical Transformation Reactions, Yingxin He

Doctoral Dissertations

“Over the past decade, laboratory-scale continuous-flow processes have witnessed explosive developments and have attracted a great deal of interest with respect to the significance of the economic and environmentally-sustainable production of pharmaceuticals, fine chemicals, and agrochemicals, as well as upgrading of biomass feedstocks. Immobilization of organocatalysts and metal nanoparticles on continuous-flow microreactors offers an efficient catalytic system that exploits and enhances the advantages of both nanocatalysis and flow chemistry, the so-called flow nanocatalysis approach. Various approaches have been developed for the development of continuous-flow reactions including immobilization and subsequent anchoring of organocatalysts and metal nanoparticles within microfluidic reactors. However, many …

Harmful Algae, Algal Toxin, Taste And Odor Control And Mitigation In Public Water System, Haiting Zhang

Doctoral Dissertations

“Recent years, harmful algal blooms occurrence has increased quickly in the surface water worldwide, which has become a concern for drinking water plants due to the ability of toxic algae (cyanobacteria) to produce cyanotoxins including microcystins (MCs), mainly MC-LR, cylindrospermopsin (CYN), and taste and odor (T&O) compounds. Various types of chemicals are widely used in drinking water treatment plants as oxidants for treating source water challenged with harmful algal blooms. In this study, the release and degradation of intracellular MC-LR due to oxidation of Microcystis aeruginosa (M. aeruginosa), most common specie of cyanobacteria, was examined kinetically. Effect of …

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. …

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 …

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 …

Advanced Topologies Of High-Voltage-Gain Dc-Dc Boost Converters For Renewable Energy Applications, Ahmad Alzahrani

Doctoral Dissertations

This dissertation proposes several advanced power electronic converters that are suitable for integrating low-voltage dc input sources, such as photovoltaic (PV) solar panels, to a high voltage dc bus in a 200 - 960 V dc distribution system. The proposed converters operate in the continuous conduction mode (CCM) and offer desirable features such as low-voltage stresses on components, continuous input currents, and the ability to integrate several independent dc input sources. First, a family of scalable interleaved boost converters with voltage multiplier cells (VMC) is introduced. Several possible combinations of Dickson and Cockcroft-Walton VMCs are demonstrated and compared in terms …

Multitarget Tracking And Terrain-Aided Navigation Using Square-Root Consider Filters, James Samuel Mccabe

Doctoral Dissertations

"Filtering is a term used to describe methods that estimate the values of partially observed states, such as the position, velocity, and attitude of a vehicle, using current observations that are corrupted due to various sources, such as measurement noise, transmission dropouts, and spurious information. The study of filtering has been an active focus of research for decades, and the resulting filters have been the cornerstone of many of humankind's greatest technological achievements. However, these achievements are enabled principally by the use of specialized techniques that seek to, in some way, combat the negative impacts that processor roundoff and truncation …

Electrodeposited Epitaxial Cobalt Oxides And Copper Metal, Caleb M. Hull

Doctoral Dissertations

"Electrochemical deposition methods are presented for the deposition of Co(OH)₂ and Cu metal. Paper I shows the deposition of β-Co(OH)₂ on Ti through electrochemical reduction of [Co(en)₃]³⁺ to [Co(en)₃]²⁺ in 2M NaOH. The catalytic properties of the deposited Co(OH)₂ towards water oxidation is found comparable to Co₃O₄, with the surface of the Co(OH)₂ converting to CoOOH during the reaction. Paper II gives the conditions suitable for epitaxial growth of Co(OH)₂ on Au(100), Au(110), and Au(111) following the same reduction mechanism as described in Paper I. …

Discrete Element And Artificial Intelligence Modeling Of Rock Properties And Formation Failure In Advance Of Shovel Excavation, Muhammad Waqas

Doctoral Dissertations

"Rock tests are performed before the start of every mining or civil engineering project as part of a detailed feasibility study. The feasibility study is costly and it comprises drilling, sample collection, sample handling and laboratory testing. Numerical modeling techniques, such as Particle Flow Code (PFC), can be used to provide reliable estimates of rock strength values. The numerical models for unconfined compressive strength (UCS), direct tension, and Brazilian tests were developed in PFC, and validated using data from literature. A particle size range of 3-5 mm with D_max/D_min = 1.67 gave the best results. The numerical …

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 …

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 …

Computational Dynamics And Virtual Dragline Simulation For Extended Rope Service Life, Muhammad Wardeh

Doctoral Dissertations

"The dragline machinery is one of the largest equipment for stripping overburden materials in surface mining operations. Its effectiveness requires rigorous kinematic and dynamic analyses. Current dragline research studies are limited in computational dynamic modeling because they eliminate important structural components from the front-end assembly. Thus, the derived kinematic, dynamic and stress intensity models fail to capture the true response of the dragline under full operating cycle conditions. This research study advances a new and robust computational dynamic model of the dragline front-end assembly using Kane's method. The model is a 3-DOF dynamic model that describes the spatial kinematics and …

Modeling And Characterization Of Thermo-Oxidative Behavior Of Bismaleimide Composites, Rafid Muhammad Hussein

Doctoral Dissertations

"High-temperature polymer matrix composites (HTPMCs) are susceptible to thermo-oxidation, which accelerates the composites' degradation and reduces the service life. Mechanical properties of HTPMCs deteriorate due to coupled thermo-oxidation and cross-linking mechanisms. Bismaleimides (BMIs) are commonly used high-temperature resins for aerospace applications. This work presents the viability of using experimental weight loss to model the spatial distribution of oxidation when the oxidized polymer matrix is not discernible. Three tasks are introduced: (1) Anisotropic oxidation prediction using optimized weight loss behavior of bismaleimide composites, (2) A multi-scale modeling of thermo-oxidative effects on the flexural behavior of cross-ply bismaleimide composites, and (3) Thermo-oxidative …

Modeling And Simulation Of Viscoplasticity, Recrystallization, And Softening Of Alloyed Steel During Hot Rolling Process, Xin Wang

Doctoral Dissertations

"Hot rolling is one of the most important and complex deformation processes in steel manufacturing and is essential to final product quality. The objective of this study is to investigate viscoplasticity, dynamic recrystallization, and static softening of alloyed metal during hot rolling process. Gleeble hot compression tests were performed to provide experimental stress-strain curves at different temperatures and strain rates. An inverse finite element analysis was performed to calibrate the experimental curves. Viscoplastic models including a Johnson-Cook (JC) model, a Zerilli-Armstrong (ZA) model, and a combined JC and ZA model were developed. Dynamic recrystallization behavior was investigated and modeled based …

Adaptive Data Analysis For Damage Detection And System Identification In Civil Infrastructure, Hongya Qu

Doctoral Dissertations

"Time-varying structural systems are often encountered in civil engineering. As extreme events occur more frequently and severely in recent years, more structures are loaded beyond their elastic conditions and may thus experience damage in the years to come. Even if structures remain elastic, energy dissipation devices installed on structures often reveal hysteretic behaviors under earthquake loads. Therefore, it is imperative to develop and implement novel technologies that enable the identification and damage detection of time-varying systems. In this dissertation, adaptive wavelet transform (AWT) and multiple analytical mode decomposition (M-AMD) are proposed and applied to identify system properties and detect damage …

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 …

Functionalized Nanoporous Carbon Scaffolds For Hydrogen Storage Applications, Christopher L. Carr

Doctoral Dissertations

"Recent efforts have demonstrated confinement in porous scaffolds at the nanoscale can alter the hydrogen sorption properties of metal hydrides, though not to an extent feasible for use in onboard hydrogen storage applications, proposing the need for a method allowing further modifications. The work presented here explores how the functionalization of nanoporous carbon scaffold surfaces with heteroatoms can modify the hydrogen sorption properties of confined metal hydrides in relation to non-functionalized scaffolds (FS). Investigations of nanoconfined LiBH₄ and NaAlH₄ indicate functionalizing the carbon scaffold surface with nitrogen can shift the activation energy of hydrogen desorption in excess of …

Critical Buckling And Post-Buckling Behavior Of Thin-Walled Liners Encased By Underground Pipelines In Saturated Soils, Zhaochao Li

Doctoral Dissertations

"This study aims to investigate the structural stability of thin-walled liners encased in functionally-obsolete underground pipelines in saturated soil under external hydrostatic pressure, a concentrated load, temperature change or their combination, and develop a simplified circular arch model of thin-walled liners when not constrained by the pipelines. The friction and adhesion on the interface between a liner and its constraining surface (pipeline or grouting), and the pressure gradient on deeply-buried pipelines are neglected. The critical buckling load of elastic liners is analytically derived under a plane strain condition using the principle of minimum potential energy. The analytical solution is either …

Engineering Zeolite Catalysts Through Porosity And Surface Acidity Control For Selective Production Of Light Olefins, Xin Li

Doctoral Dissertations

"Zeolites are broadly used as heterogeneous catalysts in various chemical and petrochemical industries to produce value-added chemicals and fuels, mainly due to their large surface area, acid-base properties, high thermal stability, and excellent shape-selectivity. In this dissertation, various zeolite catalysts were engineered through fine-tuning micro-meso-macro-porosity and surface acidity. The engineered zeolites were used as heterogeneous catalysts for production of light olefins such as ethylene and propylene through alcohol dehydration and hydrocarbon cracking reactions.

To control the zeolite porosity and acidity, SAPO-34@ZSM-5 and SAPO-34@Silicalite-1 composites with core-shell structure were synthesized and evaluated in ethanol dehydration reaction. Analysis of catalytic performance revealed …

Crustal Structure Beneath The Eastern Margin Of The Tibetan Plateau And Adjacent Areas From Receiver Function Stacking And Gravity Modeling, Yunxin Peng

Doctoral Dissertations

"To provide constraints on the mechanisms responsible for the uplift and crustal thickening of the eastern Tibetan Plateau, the thickness and Vp/Vs values of the Moho beneath 153 seismic stations are obtained by stacking P-to-S converted phases from the Moho and gravity modeling. The resulting crustal thickness generally decreases from the northwest to the south-east, from about 60 km in the Bayan Har Block to 30 km in the Sichuan Basin. The crustal Vp/Vs measurements in the Qinling Orogenic Belt, Bayan Har Block, Chuxiong Basin, and Yangtze Platform indicate an overall intermediate to felsic crustal composition. With a relatively thick …

Long-Term Behavior Of Fiber Reinforced Polymer (Frp) Confined Concrete Cylinders Subjected To Severe Weather And Seawater Solution Conditions, Song Wang

Doctoral Dissertations

"This study presents an experimental investigation on durability of fiber-reinforced polymer (FRP) confined concrete cylinders subjected to various environmental conditions. Two types of cylinders were tested in this experiment: concrete-filled FRP tube (CFFT) and hollow-core FRP-concrete-steel (HC-FCS), with FRP tubes having two different constitutive resin components: polyester and epoxy. The specimens were subjected to three different environmental conditions: combined freeze/thaw, wet/dry and heating/cooling cycles with options of continuous water immersion and sustained axial load in an environmental chamber, UV exposure in an UV chamber, and seawater immersion in water tanks with sustained axial load. Mechanical and material characterization tests were …

Adaptive Dynamic Programming With Eligibility Traces And Complexity Reduction Of High-Dimensional Systems, Seaar Jawad Kadhim Al-Dabooni

Doctoral Dissertations

"This dissertation investigates the application of a variety of computational intelligence techniques, particularly clustering and adaptive dynamic programming (ADP) designs especially heuristic dynamic programming (HDP) and dual heuristic programming (DHP). Moreover, a one-step temporal-difference (TD(0)) and n-step TD (TD(λ)) with their gradients are utilized as learning algorithms to train and online-adapt the families of ADP. The dissertation is organized into seven papers. The first paper demonstrates the robustness of model order reduction (MOR) for simulating complex dynamical systems. Agglomerative hierarchical clustering based on performance evaluation is introduced for MOR. This method computes the reduced order denominator of the transfer …

Behavior And Temporal-Based Effects Of Sustainable Self-Consolidating Concrete In Bridge Structures, Hayder Hussein Alghazali

Doctoral Dissertations

"The main objective of this study was to investigate the performance of sustainable self-consolidating concrete (SCC) for highway bridge structures. Two types of concrete were utilized in this study: high volume fly ash-self consolidating concrete (HVFA-SCC) and high strength-self consolidating concrete (HS-SCC). This dissertation consists of two major parts: a laboratory study developing and investigating the overall performance of HVFA-SCC and a field study of time-dependent field-based behavior of HS-SCC in Bridge A7957 MO, USA. In the first part, an experimental program was conducted to develop a new class of SCC incorporating up to 70% cement replacement with fly ash. …

Comprehensive Evaluation Of A Novel Eor Method-Coupling Low Salinity Water Flooding And Preformed Particle Gel To Enhance Oil Recovery In Fractured Reservoirs, Ali K. Alhuraishawy

Doctoral Dissertations

"Excess water production in oil fields is becoming a challenging economic and environmental problem as more reservoirs are maturing. Water channeling, one of the primary reservoir conformance problems, is caused by reservoir heterogeneities that lead to the development of high-permeability streaks. The recovery of oil from carbonate reservoirs is usually low due to their extreme heterogeneity caused by natural fractures and the nature of oil-wet matrix. Also, oil recovery from fractured sandstone reservoirs is often low due to areal heterogeneity. Gel treatments have proven to be a successful and inexpensive fluid diversion method when used to plug the thief zones …

Deep Learning And Localized Features Fusion For Medical Image Classification, Haidar A. Almubarak

Doctoral Dissertations

"Local image features play an important role in many classification tasks as translation and rotation do not severely deteriorate the classification process. They have been commonly used for medical image analysis. In medical applications, it is important to get accurate diagnosis/aid results in the fastest time possible.

This dissertation tries to tackle these problems, first by developing a localized feature-based classification system for medical images and using these features and to give a classification for the entire image, and second, by improving the computational complexity of feature analysis to make it viable as a diagnostic aid system in practical clinical …

Paleogene-Early Neogene Palynomorphs From The Eastern Equatorial Atlantic And Southeastern Florida, Usa: Biostratigraphy And Paleoenvironmental Implications, Walaa K. Awad

Doctoral Dissertations

"The transition from greenhouse conditions (Paleocene-Eocene Thermal Maximum, PETM) to icehouse conditions (Early Oligocene) is not well documented in tropical-subtropical regions. One hundred and five samples from Ocean Drilling Program (ODP) Site 959 (Hole 959A and Hole 959D) in the Cote d'Ivoire-Ghana Transform Margin, Alo-1 Well in the northern Niger Delta (Anambra) Basin, Nigeria, and W-17001 in southeastern Florida were studied for their palynological contents. Dinoflagellate cysts were mainly utilized for age refinement and to detect subtle changes in paleoenvironment and paleoclimate during the Paleocene-Early Eocene (ODP Hole 959D and Alo-1 Well) and Late Eocene-Early Miocene (ODP Hole 959A and …

Data Analytics For Stochastic Control And Prognostics In Cyber-Physical Systems, Shanshan Bi

Doctoral Dissertations

"In this dissertation, several novel cyber fault diagnosis and prognosis and defense methodologies for cyber-physical systems have been proposed. First, a novel routing scheme for wireless mesh network is proposed. An effective capacity estimation for P2P and E2E path is designed to guarantee the vital transmission safety. This scheme can ensure a high quality of service (QoS) under imperfect network condition, even cyber attacks. Then, the imperfection, uncertainties, and dynamics in the cyberspace are considered both in system model and controller design. A PDF identifier is proposed to capture the time-varying delays and its distribution. With the modification of traditional …

Fabrication And Characterization Of Advanced Materials Using Laser Metal Deposition From Elemental Powder Mixture, Xueyang Chen

Doctoral Dissertations

"Over the past decades of years, a great deal of money has been spent to machine large and complex parts from high-performance metals (i.e., titanium components for aerospace applications), so users attempt to circumvent the high cost of materials. Laser metal deposition (LMD) is an additive manufacturing technique capable of fabricating complicated structures with superior properties. This dissertation aims to improve the applications of LMD technique for manufacturing metallic components by using various elemental powder mixture according to the following three categories of research topics. The first research topic is to investigate and develop a cost-effective possibility by using elemental …