Engineering Commons^™

Modeling Complex Oxides: Thermochemical Behavior Of Nepheline-Forming Na-Al-Si-B-K-Li-Ca-Mg-Fe-O And Hollandite-Forming Ba-Cs-Ti-Cr-Al-Fe- Ga-O Systems, Stephen A. Utlak

Theses and Dissertations

High concentrations of Na2O and Al2O3 in the liquid high-level radioactive waste (HLW) stored at the Hanford Site can cause nepheline (NaAlSiO4) to precipitate in a vitrified monolithic waste form upon cooling. Nepheline phase formation removes glass- former SiO2 and -modifier Al2O3 from the immobilization matrix in greater proportion to alkalis, which can reduce glass durability and consequently increase the leach rate of radionuclides into the surrounding environment.

Current uncertainty in defining the HLW glass composition region prone to precipitating nepheline necessitates targeting a conservative waste loading, which raises operational costs by extending the liquid radioactive waste disposal mission and …

Numerical Analysis On Convective Cooling Augmented By Evaporative Heat And Mass Transfer For Thermal Power Plant Application, Sudipta Saha

Theses and Dissertations

This thesis work describes a numerical study on the effect of evaporative cooling on the augmentation of forced convective cooling. In recent years, on-demand phase change boosted cooling has drawn major interest where convective heat transfer is augmented/aided by evaporative heat and mass transport processes. This dual mode (convection and evaporation) cooling method is envisioned to drastically enhance the heat transfer coefficient where conventional convective cooling has already reached its maximum value and furthermore dry cooling is still a desired objective. A multi- dimensional mathematical model has been developed to conduct simulations over a range of operating parameters to obtain …

Low Frequency Injection As A Method Of Low-Level Dc Microgrid Communication, Matthew Davidson

Theses and Dissertations

In the last ten years, DC microgrid approaches have gained more popularity for the interconnection of distributed energy resources (DERs) and prosumers. The devices (generation, storage, and load) connected to the network may contain operational parameters that have the ability to be adjusted in real-time as to optimize the operation of the microgrid. In this thesis, a simple unidirectional global communication scheme is defined, implemented, and tested. The proposed approach relies on low frequency sinusoidal components that are injected into the DC microgrid power lines. Using the proposed communication approach, multiple parameters can be transmitted to the devices connected to …

Development Of Models For Road-Rail Intermodal Freight Network Under Uncertainty, Md Majbah Uddin

Theses and Dissertations

Freight activities are directly related to a country’s Gross Domestic Product and economic viability. In recent years, the U.S. transportation system supports a growing volume of freight, and it is anticipated that this trend will continue in the coming years. To support the projected increase in freight volume, an efficient, reliable, and low-cost freight logistics system is necessary to keep the U.S. competitive in the global market. In addition, intermodal transport is becoming an increasingly attractive alternative to shippers, and this trend is likely to continue as state and federal agencies are considering policies to induce a freight modal shift …

Modeling And Loss Analysis Of Sic Power Semiconductor Devices For Switching Converter Applications, Soheila Eskandari

Theses and Dissertations

Since its inception, power electronics has been to a large extent driven by the available power semiconductor devices. Switching power converter topologies, modes of operation, switching frequencies, passive filtering elements are chosen based on the switching and conduction characteristics of power semiconductor devices. In recent times new wide bandgap power semiconductor devices, such as SiC MOSFETs, are emerging with superior performance as compared to conventional silicon devices.

In switching power converter design, power losses of the power semiconductor de- vices play a crucial role in determining the physical characteristics of power converter systems in terms of size, weight, efficiency and, …

Fabrication And Characterization Of Thin Films For Heterojunction Solar Cells And Radiation Detectors, Towhid A. Chowdhury

Theses and Dissertations

The dissertation study has undertaken research in two areas: (1) development of Cu2ZnSnS4 (CZTS) thin film photo-absorber using low-cost fabrication technique for roll- to-roll commercial production for photovoltaic application, and (2) development of enriched lithium-doped amorphous selenium alloy film, a new solid-state detector material for neutron detection.

In this study CZTS thin film was developed by employing low-cost, high- throughput spray pyrolysis technique, followed by sulfurization under a 5% H2S flow at 550°C. Characterization of deposited films revealed better structural, compositional, and optical properties for sulfurized film compared to as-deposited film. The ‘sulfurized’ CZTS films deposited at 380°C substrate temperature …

Role Of P-Glycoprotein In Alzheimer’S Disease For Enhanced Brain Elimination Of Amyloid-Β, Hope Holt

Theses and Dissertations

Alzheimer’s disease (AD), the most common form of neurodegenerative disorder, is characterized by deposition of amyloid-β (Aβ) plaques in the brain. Aβ monomer undergoes nucleation to form oligomers, then soluble aggregates, then fibrils which make up the plaques. Aβ oligomer species are believed to be the most neurotoxic aggregate species. Currently under investigation is a mechanism for Aβ removal from the brain, across the blood-brain barrier (BBB). P-glycoprotein (P-gp) is a membrane-bound efflux protein located on the apical, or blood, side of the BBB, which transports a wide variety of substrates. Further complicating this potential clearance mechanism is the reduction …

Continuous Tow Path Generation For Constant And Variable Stiffness Composite Laminates On Single And Double Curved Surfaces, Caleb R. Pupo

Theses and Dissertations

A novel approach for the generation of steered tow paths on curved shell surfaces is presented. The approach is used to translate optimal theoretical analysis expressed from ply to ply as fiber angle distributions for steered laminates into discrete tow paths on planar, single and double curved surfaces. By adapting the multi mesh approach earlier developed by van Tooren and Elham [1–3] to the new tow path generation code. Two meshes are utilized, a coarse mesh which is generated during the optimization and contains the optimal fiber angle distributions, and a denser mesh obtained from tessellating the surface to better …

Beneficial Effects Of Resveratrol Against Colitis And Colorectal Cancer Mediated By The Host Microbiome, Epigenome, And Immune Response, Haider Rasheed Daham Alrafas

Theses and Dissertations

Resveratrol, a natural polyphenol compound found in red wine, the skins of grapes, and other plant products, has been used as a traditional medicine for thousands of years throughout human history, but current research has revealed this natural component is capable of modulating a variety of immunological, microbial, and epigenetic mechanisms to improve overall health and well-being of hosts that consume it. Colitis, an inflammatory bowel disease characterized by chronic inflammation in the colon and rectum, which has been associated with colon cancer. This cancer incidence is rising in younger adults in the US. Thus, newer approaches to prevent colitis …

Rage Expression And Inflammation In Alzheimer’S Disease: In Vitro Model Development And Investigation Of A Potential Peptoid Inhibitor, Lauren Michell Wolf

Theses and Dissertations

Despite the increasing prevalence of Alzheimer’s disease (AD), efforts to establish a definitive treatment or cure have met with little success. Many previous therapeutic strategies for AD have focused on the aggregation and accumulation of amyloid-b (Ab) in the brain, concentrating on its small intermediate aggregates as the primary targets to ameliorate neurotoxicity and damage. This approach has yielded little progress, and more recent discussions have shifted to strategies geared toward a multifaceted pathology, with chronic neuroinflammation emerging as an important factor in the disease etiology and progression.

The receptor for advanced glycation end-products, or RAGE, is …

Surface Science And Engineering Of Nano-Structured Cathodes For Intermediate Temperature Solid Oxide Fuel Cells, Yeting Wen

Theses and Dissertations

The bulk-to-surface Sr-segregation can seriously compromise the stability of oxygen electrocatalysis in Sr-doped perovskite oxides such as La1-xSrxCoO3-δ and La1-xSrxCo1- yFeyO3-δ and limit their practical applications as cathode materials in solid oxide fuel cells. Although such chemical instability has been actively studied in recent years, fundamental understanding of Sr-segregation process vs temperature and time, particularly under real-world conditions, as well as the suppression method, are still needed. This PhD dissertation aims to acquire fundamental knowledge of Sr-segregation process under practical conditions in solid oxide fuel cells and develop suppression method to ensure the long-term stability through surface modifications.

To gain …

Friction Stir Additive Manufacturing(Fsam) Of 2050 Al-Cu-Li Alloy, Ilana Lu

Theses and Dissertations

As a solid state process, friction stir welding (FSW) is an advantageous joining method for higher strength aluminum alloys such as 2050 Al-Cu-Li which are not readily fusion welded. This study explores the potential of friction stir lap welding (FSLW) as an additive manufacturing process for this aluminum-lithium alloy. To accomplish this, lap weld joints were performed so that each additional layer would penetrate the preceding weld pass which creates a large, stacked build. Excess material is machined away leaving only weld. Cast AA2050 is explored in this study as a more cost-efficient feedstock for this process as compared to …

Path Loss Models For Two Small Airport Indoor Environments At 31 Ghz, Alexander L. Grant

Theses and Dissertations

Path loss modeling plays a fundamental role in the design of fixed and mobile communication systems for a range of applications. Another term for path loss is channel attenuation, or reduction in signal power from transmitter to receiver. Work here was in support of a NASA project for advanced air traffic management (ATM) applications, specifically for improving the efficiency of airports. Measurements in the millimeter wave (mmWave) band were conducted at 31 GHz in indoor settings at a small municipal airport, the Jim Hamilton–L.B. Owens Airport, in Columbia, SC. Some measurements were also taken at 5 GHz for comparison. A …

Heterogeneous Catalysis For The Upgrading Of Biomass Derived Chemicals Via Hydrodeoxygenation, Elizabeth Barrow

Theses and Dissertations

An important step in the upgrading of biomass derived chemicals is the removal of excess oxygen. The works reported here are focused on studying the heterogeneous catalysts that can be utilized for that upgrading through hydrodeoxygenation. This work begins with a discussion of the alkylation of short chain platform chemicals for chain growth and also demonstrates the proof of concept of combining alkylation and hydrodeoxygenation in a single step. Then, because of the promising nature of ReOx- Pd/CeO2 for selective hydrodeoxygenation, a detailed study of ReOx/CeO2 is presented. Finally, a new surface structure interpretation is presented for P/Ni(111) which could …

Constrained Consensus In Continuous-Time Multi-Agent Systems, Zheqing Zhou

Theses and Dissertations

Since the consensus problem is getting popular in recent researches and the applications based on it are expanding in current years! the consensus problem under the condition that constraints exist on agents’ state in continuous-time in a multi-agent system has been studied here. This work combines the projection operator method in a general consensus algorithm to avoid the violation of state on its individual constraint set. When the projection operator works in the general consensus algorithm, the constraint region is divided into the projection-operator working region and the non-projection region. The boundary between these two regions is a circular line. …

Experimental Study Of Free-Solution Separation Under Pulsed Electrophoresis In Microchip, Xin Liu

Theses and Dissertations

Microchip electrophoresis (MCE) is a promising analytical tool started more than two decades. With the characteristics of short analysis time, trace level sample, high- throughput and easily integration, lots of efforts have been done with the transportation of the applications from capillary to microfabricated devices. However, with the complex designs on microchip rather than a single straight capillary channel, the strategies and approaches have to be figured out under the challenges of sample introduction, the improvement of separation conditions and the detection, for instance.

In miniaturized microchip, the separation channel is reduced to several centimeters or less, fast and quality …

Three-Dimensional Collagen Tubes For In Vitro Modeling, Rebecca Jones

Theses and Dissertations

Collagen type I represents a novel material for three-dimensional in vitro models. While two-dimensional models are typically inadequate for recreating the complex processes of the body, collagen provides a three-dimensional basis with a variety of applications, including remodeling of vascular cells under tension and vascular stenosis. Smooth muscle cells reorganize and reconstruct their environment differently under conditions of tensions, such as with sutures, or under conditions without applied external tension. Vascular stenosis, the abnormal narrowing of blood vessels, arises from defective developmental processes or atherosclerosis-related adult pathologies. Stenosis triggers a series of adaptive cellular responses that induces adverse remodeling, which …

Landslide Detection Using Remote Sensing Methods A Review Of Current Techniques, Sumanth Varma Byrraju

Theses and Dissertations

Landslides are among the most dangerous natural disasters, as they generally follow other major disasters thereby causing significant damage to already weakened systems. In the U.S. alone they cause an excess of 1 billion in damages and an average 25-50 deaths annually(USGC). Remote sensing techniques for landslide monitoring and prediction has gained popularity in recent years since it enables hazard mitigation. Synthetic Aperture Radar (SAR) interferometry is among the remote sensing techniques used. DInSAR is an advanced interferometric technique which uses radar sensors to estimate the phase of a given area from which the landslide activity can be predicted. The …

Acoustoelastic Metamaterial With Simultaneous Noise Filtering And Energy Harvesting Capability From Ambient Vibrations, Fariha Mir

Theses and Dissertations

Harvesting unused and untapped energy from ambient vibration noise and acoustic sound waves is an emerging field of research in the recent years. Utilization of the energy with a wide band of the frequency spectrum from the vibrational sources alone stands as one of the most promising ways to power small electronic devices, smartphones, local structural health monitoring (SHM) sensors and home and workshop appliances. Various sources of ambient vibration and acoustic noise can be found around us in our everyday life. These sources are abundant in almost all the engineering industries and manufacturing facilities for example in aerospace, mechanical …

Finite Element Electromagnetic (Em) Analyses Of Induction Heating Of Thermoplastic Composites, Ankit Patel

Theses and Dissertations

Thermoplastic composites are in great demand for current and future manufacturing of aircraft and automotive industries. Induction heating and welding of thermoplastic composite laminates is of great significance. The non-contact method of heating and welding is being adopted in aircraft parts, engine parts, and turbine parts manufacturing among many other things. This thesis performs simulations and analyses of Electromagnetic (EM) induction heating of thermoplastic composites materials.

The induction heating and welding of thermoplastic composites in the presence of a susceptor alloy (called Monel) consisting of 67% nickel and 27% copper is studied using a Finite Element Analysis (FEA) software. A …

Understanding The Strain Localization And Progressive Damage Growth At The Free-Edge Of Composite Laminates Using Digital Image Correlation, Addis Tessema

Theses and Dissertations

Understanding the mechanics of Fiber Reinforced Composites (FRC) that guide the design and optimization of laminate structures, have attracted numerous researchers. For the last five decades, various analytical and numerical models have been developed to understand the damage and failure mechanisms in FRC. For long, Classical laminate plate theory (CLPT) has majorly been used as a theoretical guide in the design of composite structures. The CLPT framework is developed based on the consideration of an infinitesimal wide plate that depicts a planar stress condition. Thus, as it considers only the planar stresses, the out of plane interlaminar stresses are absent …

The Use Of Multi-Targeting Natural Products For The Treatment Of Cancer, Wesley Taylor

Theses and Dissertations

The paradigm shift in cancer treatments from traditional chemotherapeutics to targeted therapies has rapidly improved prognoses for patients for whom cancer was once a death sentence. This is especially true in the case of targeted immune therapies which activate the body’s own natural defense system to fight cancer. Despite these advances, however, cancer remains the second leading cause of death in the United States. The promise of targeted therapeutics has faced significant hurdles in providing effective cancer treatments, namely the limited percentage of susceptible cancers for each treatment, high cost burden, high toxicities, and significant risk of treatment induced resistance. …

Three-Dimensional Plasma Cell Survival Microniche In Multiple Myeloma, Katrina A. Harmon

Theses and Dissertations

Multiple myeloma (MM) is an incurable malignancy characterized by the uncontrolled proliferation of long-lived plasma cells (PCs) in the bone marrow (BM), which constitute at least 10% of BM cellularity. Normally, long-lived plasma cells make up less than 1% of BM cells. Plasma cells become neoplastic when a clonal PC population produces a monoclonal immunoglobulin protein. A diagnosis of monoclonal gammopathy of undetermined significance (MGUS) is made when there is an increase in monoclonal PCs within the BM, but less than 10%, and the patient does not present with end-organ damage, which is associated with active MM. Though not considered …

Biophysical Analyses Of Left Ventricular Remodeling Secondary To Myocardial Infarction And Left Ventricular Pressure Overload, William Manuel Torres

Theses and Dissertations

Left ventricular (LV) remodeling is nominally an adaptive process that restores biomechanical function following myocardial injury and/or sustained alterations in loading conditions. This remodeling can materialize as changes in myocardial geometry, composition, and mechanical properties. When these changes fail to restore LV biomechanical function, remodeling is termed maladaptive. It is generally accepted that maladaptive LV remodeling underlies the progression to heart failure in various forms of heart disease. The central hypothesis of this study is that we can leverage echocardiographic imaging techniques to non-invasively quantify changes in biomechanical function and mechanical properties in a serial manner throughout the progression towards …

A Partially Automated Process For The Generation Of Believable Human Behaviors, Bridgette Parsons

Theses and Dissertations

Modeling believable human behavior for use in simulations is a difficult task. It re- quires a great deal of time, and frequently requires coordination between members of different disciplines. In our research, we propose a method of partially automating the process, reducing the time it takes to create the model, and more easily allowing domain experts that are not programmers to adjust the models as necessary. Using Agent-Based modeling, we present MAGIC (Models Automatically Generated from Information Collected), an algorithm designed to automatically find points in the model’s decision process that require interaction with other agents or with the sim- …

Analysis Of Cellular Interactions Within A Collagen Hydrogel, Austin N. Worden

Theses and Dissertations

Evidence has arisen over the past several years that use of a three- dimensional (3D) culture system provides a distinct advantage over two- dimensional (2D) systems when cellular interactions are examined in a more natural environment. Changes in morphology, speed, and directionality of cells tested in both planar and 3D matrices have all demonstrated that using 3D system is advantageous. The changes to the cellular migration patterns were shown to be dependent on several variables within the surrounding substrate including cellular content, physical environment, and the matrix chemical milieu. We have taken advantage of using collagen hydrogels as a 3D …

Development Of Scalable And Tunable Super- Hydrophilic And - Hydrophobic Coatings On The Cu Substrate For Phase Change Heat Transfer Applications, Raikan Saad Dawas

Theses and Dissertations

The aim of this study is to enhance and sustain the thin liquid film evaporation (TLFE) as well as dropwise condensation (DWC) on scalable copper substrates. The current dissertation consists of two sections. The objective of the first section is to enhance the dry cooling technology which is widely used in industrial applications such as in the air side of power plants, AC unit, or electronic cooling. However, the thermal dissipation performance is limited with low heat transfer coefficients (HTCs) due to the low thermal conductivity and density of the air. Inspired by the phase change heat transfer during the …

An Anatomical Basis Of The Differential Cholinergic Modulation Of Valence-Specific Pyramidal Neurons In The Basolateral Amygdala, Nguyen Vu

Theses and Dissertations

Emotion is a crucial component of the decision-making process. The amygdala, known as the “orchestrator” of the emotion circuit, associates emotional valence with incoming sensory stimuli and thus contributes to decision- making. Within the basolateral nucleus of the amygdala (BLA), spatially segregated and genetically distinct pyramidal neurons (PNs) have been identified based on their correspondence to distinct behavioral stimuli. These PNs project to several brain regions mediating different aspects of the emotional spectrum.

For example, BLA PNs projecting to prelimbic (PL) and infralimbic (IL) cortex are involved in fear acquisition and fear extinction, respectively. However, the mechanism by which these …

Electrode Development And Electrocatalysts Design For Polymer Electrolyte Membrane Fuel Cells, Xiong Peng

Theses and Dissertations

Because of environmental issues and national conflicts caused by overuse of fossil fuels, there is a need to seek renewable ways to utilize energy. In the transportation sector, hydrogen-based polymer electrolyte membrane fuel cells, including proton exchange membrane fuel cells (PEMFCs) and anion exchange membrane fuel cells (AEMFCs), have been considered as a promising alternative to conventional combustion engines. However, the widespread commercialization of both PEMFCs and AEMFCs has been hindered by several factors, including cost and performance. In this thesis, a series of topics including electrode fabrication, electrocatalyst development for both PEMFCs and AEMFCs, as well as the water …