Digital Commons Network^™

Multi-Scale Modeling Of Particle-Laden Flows, Anand Samuel Jebakumar

Open Access Dissertations

Particle-laden flow occur in a wide range of engineering applications such as combustors, gasifiers, fluidized beds and pollution control systems. Particle-flow interactions are complex, especially in turbulent and confined flows. A proper understanding of these interactions is critical in designing devices with better performance characteristics. In this work, particle-laden flows in channels are numerically investigated with the lattice-Boltzmann method (LBM). A three-dimensional parallelized lattice-Boltzmann method code is developed to carry out these studies. The code resolves the particle surface and the boundary layer surrounding it to gain fundamental insights into particle-flow interactions. The lattice-Boltzmann method is assessed for its accuracy …

System And Thermal Modeling Of Hydraulic Hybrids: Thermal Characteristics Analysis, Hyukjoon Kwon

Open Access Dissertations

Hybrid vehicles have become a popular alternative to conventional powertrain architectures by offering improved fuel efficiency along with various other environmental benefits. Among them, hydraulic hybrid vehicles (HHVs) have several benefits, which make it the superior technology for certain applications over other types of hybrid vehicles, such as lower component costs, more environmentally friendly construction materials, higher power densities, and more regenerative energy available from braking. There have been various studies on HHVs, such as energy management optimization, control strategies for various system configurations, the effect of system parameters on the hybrid system, and proposals for novel hybrid architectures. One …

The Impact Of Host Variables And Tumor Necrosis Factor On The Gut Microbiome In A Mouse Model Of Crohn's Disease, Ariangela J. Kozik

Open Access Dissertations

Crohn’s Disease (CD) and Ulcerative Colitis (UC) are chronic, inflammatory conditions of the digestive tract that are collectively known as Inflammatory Bowel Disease (IBD). Currently, IBD has no cure and the exact mechanisms of disease development and progression are unknown. The gut microbiome is the collection of microbes that reside in the digestive tracts of humans and animals, and it has been shown to be associated with a variety of diseases, including IBD. Mouse models of colitis are often used to investigate the role of the gut microbiome in IBD. In this work, I investigated the role of tumor necrosis …

Stereotype Threat, Perfectionism, And Women's Career Outcomes, Chaihua Lin

Open Access Dissertations

The underrepresentation of women in science, technology, engineering, and mathematics (STEM) calls for efforts to understand factors that contribute to women’s career development in STEM fields. Using social cognitive career theory (SCCT), this study examines how the interplay of individual and contextual factors (i.e., perfectionism and stereotype threat) contributes to the academic and career outcomes of women STEM students (i.e., self-efficacy, outcome expectation, interest, goals, and procrastination). Hypotheses regarding the relationships among these variables, as well as the moderating role of perfectionism on the mediated effect of stereotype threat on interest through self-efficacy were assessed. Data was collected from 323 …

Data Compression In Multi-Hop Large-Scale Wireless Sensor Networks, Yimei Li

Open Access Dissertations

Data collection from a multi-hop large-scale outdoor WSN deployment for environmental monitoring is full of challenges due to the severe resource constraints on small battery-operated motes (e.g., bandwidth, memory, power, and computing capacity) and the highly dynamic wireless link conditions in an outdoor communication environment. We present a compressed sensing approach which can recover the sensing data at the sink with good accuracy when very few packets are collected, thus leading to a significant reduction of the network traffic and an extension of the WSN lifetime. Interplaying with the dynamic WSN routing topology, the proposed approach is efficient and simple …

Structural, Thermodynamic, And Electronic Properties Of Mixed Ionic/Electronic Conductor Materials, David M. Guzman

Open Access Dissertations

Due to the mainstream CMOS technology facing a rapid approach to the fundamental downscaling limit, beyond CMOS technologies are under active investigation and development with the intention of revolutionizing and sustaining a wide range of applications including sensors, cryptography, neuromorphic and quantum computing, memory, and logic, among others. Resistive switching electronics, for example, are devices that can change their electrical resistance with an applied external field. Despite their simple metal-insulator-metal structure, resistive switching devices exhibit an intricate set of IV characteristics based on the chemical composition of the solid electrolyte that ranges from non-volatile bipolar and non-polar switching to volatile …

Design And Analysis Of Sodium-Cooled Fat Reactor Systems For Nuclear Waste Minimization, Ching-Sheng Lin

Open Access Dissertations

The primary objective of this study was to develop fuel cycle options that minimize the nuclear waste generation using sodium-cooled fast reactor systems. In addition, this study aims to develop a new method that improves the accuracy in analyzing one of the developed options that the moderated target assembly was loaded in the fast reactor core. This document summarizes the objectives and lines of work focused on the design studies and performance analyses of transuranic (TRU) elements transmutation in fast reactor systems, the development of new depletion method, and the assessment of how well the design meets the objectives. Two …

Evaluation Of Redundancy In Composite Twin-Tub-Girder Bridges With Finite Element Analysis, Cem Korkmaz

Open Access Dissertations

High torsional rigidity and attractive aesthetics in construction of twin-tub-girder bridges make them preferable for the design of curved bridges. However, according to the concepts associated with the term “Fracture Critical (FC)” that are in place today, all two-girder bridges are always classified as having FC members. For a steel bridge with FC members, the fracture of any of its members may result in complete catastrophic failure or significant loss of serviceability; hence, every two years twin-tub-girder bridges are subjected to very expensive hands-on field inspection. Full-scale simple span twin-tub-girder bridge tests at University of Texas Austin have demonstrated excessive …

Geometric Measure Theory With Applications To Shape Optimization Problems, Qinfeng Li

Open Access Dissertations

This thesis mainly focuses on geometric measure theory with applications to some shape optimization problems being considered over rough sets. We extend previous theory of traces for rough vector fields over rough domains and proved the compactness of uniform domains without uniformly bounded perimeter assumption. As application of these results, together with some other tools from geometric analysis, we can give partial results on the existence and uniqueness of minimizers of the nematic liquid droplets problem and the thermal insulation problem. Two other geometric minimization problems with averaged property, which include the generalized Cheeger set problem, are also studied.

Airborne Challenges To Vocal Folds: Studies On Barrier Function And Inflammation, Xinxin Liu

Open Access Dissertations

The vocal folds are located in the larynx and are responsible for voice production. The epithelium of the vocal folds is of the stratified squamous type. These epithelial cells along with the characteristic tight junctional complex create an active barrier, that protects the underlying connective tissue against air-borne xenobiotics. Damage to the epithelium can lead to penetration of xenobiotics and may cause inflammation in connective tissue. Particles and chemicals have different physical properties and have different capacities for penetrating epithelium and inducing inflammation in underlying tissues. In this study, we investigated the effects of one type of particle (single-walled carbon …

Transportation System Performance Measures Using Internet Of Things Data, Mathew Jijo Kulathintekizhakethil

Open Access Dissertations

The transportation system is undergoing a rapid change with innovative and promising technologies that provide real-time data for a variety of applications. As we transition into a technology-driven era and Internet of Things (IoT) applications, where everything is connected via a network of smart sensors and cloud computing, there will be an increasing amount of real-time data that will allow a better understanding of the transportation system. Devices emerging as a part of this connected environment can provide new and valuable data sources in a variety of transportation areas including safety, mobility, operations and intelligent transportation systems. Agencies and transportation …

Novel Multiphysics Phenomena In A New Generation Of Energy Storage And Conversion Devices, Arpan Kundu

Open Access Dissertations

The swelling demand for storing and using energy at diverse scales has stimulated the exploration of novel materials and design strategies applicable to energy storage systems. The most popular electrochemical energy storage systems are batteries, fuel cells and capacitors. Supercapacitors, also known as ultracapacitors, or electrochemical capacitors have emerged to be particularly promising. Besides exhibiting high cycle life, they combine the best attributes of capacitors (high power density) and batteries (high energy storage density). Consequently, they are expected to be in high demand for applications requiring peak power such as hybrid electric vehicles and uninterruptible power supplies (UPS). This dissertation …

British Essentialism In Eighteenth-Century British Travel Literature Of The West Indies And North America, Stephanie Matos-Ayala

Open Access Dissertations

This dissertation explores issues of representation and cultural negotiation by examining how the white colonial other was depicted in eighteenth-century travel literature, specifically Janet Schaw’s Journal of a Lady of Quality written during the years 1774 to 1776. Travel narratives and histories speak to many different topics, yet they reveal the most about eighteenth-century British ways of thinking about race and national identity, more so than about the various peoples and cultures they seek to describe. I argue that this literature reveals a hierarchy based on the absorption and consumption of British practices and goods by the colonial subject. Neither …

Signal Processing For Caching Networks And Non-Volatile Memories, Tianqiong Luo

Open Access Dissertations

The recent information explosion has created a pressing need for faster and more reliable data storage and transmission schemes. This thesis focuses on two systems: caching networks and non-volatile storage systems. It proposes network protocols to improve the efficiency of information delivery and signal processing schemes to reduce errors at the physical layer as well. This thesis first investigates caching and delivery strategies for content delivery networks. Caching has been investigated as a useful technique to reduce the network burden by prefetching some contents during o˙-peak hours. Coded caching [1] proposed by Maddah-Ali and Niesen is the foundation of our …

Horses In Agriculture Online: Designing, Developing, And Assessing Situational Interest An Online Museum Exhibit Using The Systems Approach Model Of Instructional Design, Elisa Anne Lofgren

Open Access Dissertations

Research on motivations of learners has been done in traditional museum environments, but the research of online museum exhibits is in its infancy. While variables such as interactivity have been explored in traditional museum exhibits, little is still known about how these variables affect visitor experiences in online applications. It is important to know if the application of technology into these programs, such as online learning experiences and corresponding characteristics such as interactivity, free-choice use, and adaptive/adaptable e-learning effects the learner experience. This study follows a formal process of instructional design to develop an online educational resource to be used …

Global Analyses Of Protein Complex Localization, Oligomerization, Composition, And Dynamics Using Quantitative Mass Spectrometry, Zachary M. Mcbride

Open Access Dissertations

Proteins perform essential processes in plant cells such as photosynthesis, protein translation, maintenance of metabolic flux, and signal transduction. Many of these functions could never be achieved using individual proteins. Consequently, many proteins oligomerize to form complexes that act as tunable molecular machines that perform work and transmit information. Cells contain thousands of protein complexes, yet the composition of the vast majority remain unknown. Previous high throughput approaches to identify protein interactions have relied on binary interactions or tagging individual proteins for purification. A new set of label free correlation profiling methods were developed that extracted native protein from Arabidopsis …

Connected Vehicle Data-Based Tools For Work Zone Active Traffic Management, Michelle Mekker

Open Access Dissertations

Work zones present challenges to safety and mobility that require agencies to balance limited resources with vital traffic management activities. It is important to obtain operational feedback for successful active traffic management in work zones. Extensive literature exists regarding the impact of congestion and recommendations for work zone design to provide safe and efficient traffic operations. However, it is often infeasible or unsafe to inspect every work zone within an agency’s jurisdiction. This dissertation outlines the use of connected vehicle data, crash data, and geometric data from mobile light detection and ranging (LiDAR) technology for active traffic management in work …

Effects Of Anaerobic Digestion On Nutrient Conversion And Digestate Land Application On Nutrient Losses, Igor Moreira Lopes

Open Access Dissertations

The adoption of anaerobic digestion (AD) at agricultural systems as an alternative technology for waste management and renewable energy production has raised the concern regarding the value of AD digestate as fertilizer and the environmental impact of the digestate land-application. This Ph.D. research project aimed to gain new knowledge into the impact of AD on digestate characteristics in comparison with the digester feedstock, and the impact of digestate as fertilizer on water quality in comparison with inorganic fertilizer and raw manure. The project was divided into four different studies: a digestate characterization study and three digestate application studies. The digestate …

The Effectiveness Of Visual Input Enhancement Across Multiple Proficiency Levels On The Noticing And L2 Development Of German Vocabulary And Reading, Christopher La Cross

Open Access Dissertations

The present study investigates the effectiveness of visual input enhancement across multiple proficiency levels on the noticing and L2 development of German vocabulary and reading. The study addresses several methodological issues in the extant literature and uses a complex organization to investigate possible differences in the effectiveness of visual input enhancement, a frequently used technique in L2 reading, across multiple proficiency levels in a typical L2 classroom setting at the university level. The study reveals that little to no differences exist across proficiency level and text level and that visual input enhancement, as is so often employed, has extremely limited …

Investigations Of The Electrical, Vibrational And Optical Properties Of Graphene-Based Materials, Ting-Fung Chung

Open Access Dissertations

Graphene and its hybrids have stimulated significant scientific interest owing to their unique properties and technological importance. In this dissertation, we investigate the vibrational, electrical, and optical properties of these remarkable low-dimensional materials by multiple methods including optical measurements (Raman spectroscopy and photoelectrical measurements) and electrical transport measurements (such as the temperature and magnetic field dependence studies). The materials studied have been synthesized or fabricated by methods including chemical vapor deposition (CVD) as well as mechanical exfoliation and transfer.

Twisted bilayer graphene (tBLG) exhibits distinct physical properties compared to monolayer and Bernal-stacked bilayer graphene counterparts. In particular, the electronic structures …

Effects Of Reduced Dietary Crude Protein On Gaseous Pollutant Emissions From A Swine Research Building, Shule Liu

Open Access Dissertations

Swine production is a primary source of protein and fat to human society, in the meanwhile, it continuously emits undesirable pollutant gases, including ammonia (NH3), hydrogen sulfide (H2S), carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), imposing adverse impacts on animal and human health as well as on the environment. Previous studies proved that reducing excessive dietary N was effective in mitigating NH3 emissions from pig production, but the reduction in NH3 emissions during different swine physiological stages were not reported yet as only a few studies were based on continuous monitoring in the field. Moreover, the effects of …

Part I: Polyrotaxanes As Mri Contrast Agents And Npc Therapeutics. Part Ii: Development Of An Analytic-Directed Synthesis System, Bradley P. Loren

Open Access Dissertations

The work described in this dissertation is separated into two parts. Part I describes the development of cyclodextrin-based polyrotaxanes (PRs) as both MRI contrast agents and as potential therapeutics for Niemann-Pick Type C (NPC) disease. Polyrotaxanes are a class of supramolecular materials which are constructed through the non-covalent threading of macrocyclic molecules onto a polymer core that are retained by the covalent attachment of bulky molecules to the ends of the polymer as end-caps. This unique architecture provides a rigid and rod-like morphology that imparts attractive biological and mechanical properties compared to other nanomaterials used in biological applications. In our …

Yshb Is A Positive Regulator For Salmonella Intracellular Survival And Facilitates The Spatio-Temporal Regulation Of Bacterial Pathogenesis, Rajdeep Bomjan

Open Access Dissertations

Salmonella pathogenesis primarily involves invasion of host cells followed by modulation of the intracellular environment for survival and replication. While tremendous progress has been made toward understanding the pathogenesis, the picture is far from complete. In an effort to characterize the role of small RNAs (sRNAs) in Salmonella pathogenesis, we identified a previously undefined small protein YshB as a positive regulator for intracellular bacterial survival and virulence. Essentially, we were able to show YshB was important for survival within macrophages and contributed significantly in mouse virulence. Further, when induced within the bacteria, YshB would lower the invasion efficiency. Notably, yshB …

Batf Regulation Of Nfil3, Wnt10a, And Mir155hg During Lymphocyte Activation Critical For T Cell Differentiation And Antibody Class Switch Recombination, Rosemary E. Morman

Open Access Dissertations

B cell activating transcription factor (BATF), an immune specific AP-1 transcription factor, functions together with IRF4 and JUNB to regulate genes important for antibody class switch recombination (CSR) in B cells and for the functional differentiation of distinct CD4+T helper (Th) subsets, including Th2, Th9, Th17 and T follicular helper cells. At the time this work was initiated, the expression of BATF in T cells and B cells was known to be critical to the host response to antigen and for the production of class switched immunoglobulins, yet the precise details of how BATF functioned in those roles was unknown. …

Interplay Of Endogenous And Exogenous Biochemical Species On Neuropathic Pain After Spinal Cord Injury, Breanne Suzanne Muratori Butler

Open Access Dissertations

Neuropathic pain after spinal cord injury (SCI) presents a complex clinical challenge, affecting millions with no satisfactory treatment options currently available. Much of the recent research focuses on a wide variety of endogenous mechanisms that can contribute to pain, but have yet to produce positive results in clinical studies. This dissertation focuses on the role of a highly reactive and toxic aldehyde, acrolein, in initiating, instigating, and perpetuating neuropathic pain after spinal cord injury. Acrolein is shown to mimic damage caused by an injury, in the absence of mechanical trauma. Additionally, removing it using acrolein scavengers can mitigate neuropathic pain-like …

Plant Cell Wall Modification During Tomato Processing And Its Effects On The Physical And Rheological Properties Of End Products, Xing Fei

Open Access Dissertations

Understanding the relationship between structure and functional properties in plant-cell-wall-derived foods has become a growing interest to both academia and industry. Tomato is one of the most cultivated vegetable crops and mostly is consumed as processed products in the form of suspensions. Rheological properties of tomato product, a key functional attribute, depends on both the serum and particle phases of these products. Although recent studies have suggested that the particle phase is the dominant factor, the relationship between fundamental particle properties and the bulk rheology of the suspension is still unclear. This research systematically evaluated the contributions of soluble pectin …

Studies On Imaging System And Machine Learning: 3d Halftoning And Human Facial Landmark Localization, Ruiyi Mao

Open Access Dissertations

In this dissertation, studies on digital halftoning and human facial landmark localization will be discussed. 3D printing is becoming increasingly popular around the world today. By utilizing 3D printing technology, customized products can be manufactured much more quickly and efficiently with much less cost. However, 3D printing still suffers from low-quality surface reproduction compared with 2D printing. One approach to improve it is to develop an advanced halftoning algorithm for 3D printing. In this presentation, we will describe a novel method to 3D halftoning that can cooperate with 3D printing technology in order to generate a high-quality surface reproduction. In …

Understanding Macroscale Patterns And Processes Of Invasion, Gabriela Nunez-Mir

Open Access Dissertations

The increasing rate of biological invasions and their impacts are one of the major threats in the Anthropocene. However, certain knowledge gaps remain in our understanding of patterns and processes of invasion, despite an extensive body of research dedicated to this phenomenon. Highly-debated topics in invasion ecology could benefit from a macrosystems perspective. Studies performed at the macroscale are able to capture the effect of global-level processes that drive invasions, detect patterns that transcend taxonomic and geographic boundaries, and minimize biases stemming from the specificity of studies performed at more localized scales. Here, I aim to provide novel insights into …

Modeling And Simulation Of Multiphase Flow Between Rotating And Stationary Disks, Irsha Pardeshi

Open Access Dissertations

The Clutch in an automotive vehicle transfers power from the engine to the wheels with the speed and torque controlled by a gearbox. To accommodate different speeds and loads, different gear ratios are needed, and the clutch disengages and engages every time those ratios are changed. Since heat is generated when disengaged and when suddenly engaging, lubricating oil is pumped throughout the clutch to cool and to reduce friction. When the clutch is disengaged, drag torque is generated. Drag torque is due to the viscous force from the relative motion between the friction (rotating) disk and the separator (stationary) disk. …

A Molecular Perspective For The Understanding Of Polymer‒Drug Interactions, Laura Isabel Mosquera Giraldo

Open Access Dissertations

Polymers are often used to stabilize amorphous drug formulations enabling the maintenance of high drug supersaturations. However, the molecular mechanism of stabilization is unclear, making the rational design of new polymers challenging. This research has focused on understanding the effectiveness of polymers to inhibit drug crystallization using experimental and computational modeling approaches. This thesis has six sections. The first section reviews the pharmaceutical significance of amorphous solid dispersions. The second section describes a study to evaluate the phase behavior of supersaturated drug solutions of telaprevir, a compound that undergoes glass-liquid phase separation when the amorphous solubility is exceeded. The third …