Digital Commons Network^™

Sublaplacians On Real Flag Manifolds, Andrew Ursitti

Open Access Dissertations

Hypoelliptic differential operators and associated geometries with origins in Lie theory are studied. We prove upper bounds on the dimension of Killing fields of analytic pseudosubriemannian manifolds under certain technical hypotheses. Existence and uniqueness results for adapted complex structures in open subsets of cotangent bundles of analytic subriemannian manifolds are proved. A generalized Lichnerowicz theorem expressing the difference between a connection laplacian and a Dirac laplacian for arbitrary linear connections and quadratic forms is proved, along with a preliminary result in local index theory for subriemannian metrics. We prove general results on the ubiquity of hypoelliptic sublaplacians arising in reductive …

Assessing Novel Bioelectric Effects Of Nanosecond Pulsed Electric Fields On Cell Stimulation, Proliferation And Microorganism Inactivation, Ram Anand Vadlamani

Open Access Dissertations

Bioelectrics is the application of electric fields to cells in a conducting media, treating the cell as a circuit comprising resistors and capacitors (membranes and intracellular fluids respectively). Recent advancements in construction of nanosecond pulse generators allow for construction of low cost devices capable of generating nanosecond pulsed electric fields (nsPEFs). These fields are capable of forming pores on the extra and intra cellular membranes, while also affecting intracellular organelles, DNA and the nucleus. With the first generation of nano-signalling devices set to enter the medical field for treatments ranging from carcinomas to regenerative therapy, the intent of this study …

Essays In Labor Economics And Applied Microeconomics, Paul W. Thomas

Open Access Dissertations

The first chapter of this dissertation is titled ”Childhood Family Income and Adult Outcomes: Evidence from the EITC.” Many researchers have explored the impact of family income on children by utilizing structural changes in the Earned Income Tax Credit (EITC). However, most of this previous research focuses on childhood outcomes, such as effects on the child’s performance in school or effects on health and behavior. This paper is one of the few that estimates the effect of childhood family income on adult outcomes. In order to overcome the confounding relationship between childhood family income and future employment, this paper uses …

Polymer Solution Rheology And Polymer Synthesis For Enhanced Oil Recovery, Anna Veronica Walter

Open Access Dissertations

Enhanced Oil Recovery (EOR) is used to access the oil within oil basins that remains after traditional recovery methods are deployed. In alkali-surfactant-polymer EOR, aqueous solutions containing surfactants and high molecular weight polymers are injected into oil basins. The most common polymer used in polymer EOR is partially hydrolyzed polyacrylamide (HPAM), a copolymer of polyacrylamide and polyacrylic acid, and in aqueous solutions, HPAM is a polyelectrolyte. The presence of salts in the oil basin and in water used to make industrial injection solutions can alter the interactions of these anionic charges. By knowing the rheological behavior of polymer solutions containing …

Non-Suicidal Self-Injury In First-Year College Students: The Testing Of A Nonlinear Integrated Model, Natasha Pryde Trujillo

Open Access Dissertations

Non-suicidal self-injury (NSSI) is an increasing concern among college students (Whitlock, Muehlenkamp, & Eckenrode, 2008). First-year college students, who are in the midst of transitioning to the college environment, are often at increased risk for problematic behaviors or maladaptive coping as they adjust to the varied changes that take place during this crucial developmental phase (Chickering & Reisser, 1993, Fromme, Corbin, & Krause, 2008). First-year college students may be at particular risk for NSSI engagement because of the developmental, interpersonal, and intrapersonal demands that accompany the transition to college. Further, first-year students who have experienced aversive life events connected to …

Induced Superconductivity In Two Dimensional Electron Gas System, Zhong Wan

Open Access Dissertations

Recently, interest in superconductor-semiconductor interfaces was renewed by the search for non-Abelian states. One of the possible platform is proximity induce superconductivity into an 1D semiconductor system with strong spin orbit (SO) interaction, such system is predicted to support Majorana excitation. Another candidate is superconductivity coupled to the edge of fractional quantum Hall state, in such system, higher order of non-Abelian statistics is predicted. With such non-Abelian states, topological quantum computing can be realized. In this thesis, I will discuss the approach made by us to investigate such system.

The thesis will begin with a brief review of superconducting proximity …

Effects Of Schisandrin B On Rod Photoreceptors In The Pde6c Larval Retina, Prahatha Venkatraman

Open Access Dissertations

Current Rapid prototyping tools although reduce development time, they still have several restrictions such as print volume and print times. Through this thesis, two prototyping kits are proposed, a rod connector based, user controlled computational support system that re-purposes surface models and transforms them into structurally scaffolded constructs with movable joints; and a planar connector based system that implements movable joints to create functional prototypes. The rod based system enables users to interactively personalize scaffolded structures by re-purposing existing surface mesh models; analyze scaffolded constructs in-situ for better structurality, add movable joints to increase functionality, and attach personalized appearances to …

Modulating Wettability Of Layered Materials By Controlling Headgroup Dynamics And Alkyl Chain Conformations, Terry Angelo Villarreal

Open Access Dissertations

Evolution to the next generation of organic photovoltaics and computer processors requires the capability to pattern organic and inorganic materials consistently at interfaces with feature sizes as small as 5-7 nm. A particular challenge is to generate interfaces that display chemical patterns consisting of two or more very different constituents at such scales. Biology routinely orders orthogonal chemical patterns at this scale, as is observed in the structure of the cellular membrane. Phospholipids have also been observed to form repeating striped phases on layered materials, e.g. graphene, molybdenum disulfide (MoS2), and highly oriented pyrolytic graphite (HOPG).

Research performed in the …

Catalytic Conversion Of Light Hydrocarbons To Chemicals And Fuels, Han-Ting Tseng

Open Access Dissertations

The recent surge in shale gas production throughout the United States has led to increased interest in hydrocarbon upgrading such as C—H bond activation and light hydrocarbons conversion to fuels. Methane and other light alkanes in natural gas can be potentially converted into light olefins, which can be further utilized as basic building block for valuable chemicals or upgraded to long-chain hydrocarbons used as fuels.

In the first work, kinetic study on Mn/Na2WO4/SiO2 catalyst for oxidative coupling of methane (OCM) into ethane and ethylene were performed with varying Mn (0-2 wt%) and W (0-3.1 wt%) loadings. When the W loading …

Modeling Electronic Transport In Metal Interconnects, Daniel Valencia

Open Access Dissertations

The improvements in the density of integrated circuits and device performance have been achieved through a long journey of device downscaling and increase in chip size. The tremendous push of the industry to aggressively scale devices has increased parasitic effects generated by an increase in the resistivity of the wire metallization which negatively affects the chip performance. Therefore, a careful design of interconnects is essential to reduce these parasitic effects. This work presents the first study where a fully atomistic basis has been used to describe realistic copper interconnects as used in the industry to identify the effects on resistivity. …

Prompt D0 Meson Nuclear Modification Factor And Azimuthal Anisotropy In Heavy Ion Collisions With Cms, Jian Sun

Open Access Dissertations

The primary goal of heavy ion physics is to study the properties of the Quark Gluon Plasma (QGP), a state of matter comprising deconfined quarks and gluons. Heavy quarks (charm and bottom) are effective probes to study the properties of the QGP produced in heavy ion collisions. Because of their large masses, heavy quarks are primarily produced via initial hard scatterings in heavy ion collisions. They are expected to interact with the QGP differently than light quarks and gluons. The comparison between the nuclear modification factors of heavy flavor and light hadrons can provide insights into the expected flavor dependence …

Environmental Life Cycle Impact And Complexity Assessment Of Rare Earth Production, Ehsan Vahidi Movassagh

Open Access Dissertations

Rare Earth Elements (REEs) find applications in clean energy technology, including wind turbines, electric vehicles, and high efficiency lighting therefore, as the renewable energy market expands, demand of REEs is anticipated to rise. However, it is well known that the production of REEs carries large environmental burden and as a result, reducing environmental footprints of REE production becomes critical. The first action towards reducing the environmental degradation during production of REEs is the thorough examination of the energy requirements and environmental emissions. To date, Life Cycle Assessment (LCA) is the standard methodology to evaluate the environmental performance of a system, …

Trajectory Optimization And Guidance Design By Convex Programming, Zhenbo Wang

Open Access Dissertations

The field of aerospace guidance and control has recently been evolving from focusing on traditional laws and controllers to numerical algorithms with the aim of achieving onboard applications for autonomous vehicle systems. However, it is very difficult to perform complex guidance and control missions with highly nonlinear dynamic systems and many constraints onboard. In recent years, an emerging trend has occurred in the field of Computational Guidance and Control (CG&C). By taking advantage of convex optimization and highly efficient interior point methods, CG&C allows complicated guidance and control problems to be solved in real time and offers great potential for …

Model Based Clustering Algorithms With Applications, Wutao Wei

Open Access Dissertations

In machine learning predictive area, unsupervised learning will be applied when the labels of the data are unavailable, laborious to obtain or with limited proportion. Based on the special properties of data, we can build models by understanding the properties and making some reasonable assumptions. In this thesis, we will introduce three practical problems and discuss them in detail. This thesis produces 3 papers as follow:

Wei, Wutao, et al. ”A Non-parametric Hidden Markov Clustering Model with Applications to Time Varying User Activity Analysis.” ICMLA2015 (1) Wei,Wutao, et al. ”Dynamic Bayesian predictive model for box office forecasting.” IEEE Big Data …

Program Transformation For Secure And Sustainable Web Applications, Weihang Wang

Open Access Dissertations

Web advertising is a multi-billion-dollar industry. As a primary source of income for many Internet companies, web advertising (ads) has a profound impact on the security and sustainability of today’s web ecosystem. Web advertising, however, is extremely complex and highly vulnerable to attacks. In fact, attackers using the web advertising system as a channel to spread malware has become some of today’s largest web-based attacks. To protect users from malicious advertising, we develop a memory randomization system, PAD, that effectively prevents malicious advertising (malvertising) attacks exploiting zero-day vulnerabilities.

To reduce the risk of malicious ads and remove unwanted ads, recent …

Materials Design With Molecular Dynamics: Novel Properties In Martensitic Alloys Through Free Energy Landscape Engineering, Samuel Temple Reeve

Open Access Dissertations

Novel properties in martensitic alloys are predicted using molecular dynamics (MD) simulations, the uncertainty from input models in MD is explored and quantified, and new data infrastructure for MD is developed.

The possible regimes of material properties are extended through free energy landscape engineering (FELE), where coherent, epitaxial integration of two materials at the nanoscale can result in metamaterials with fundamentally different behavior. Free energy as a function of strain is calculated using MD simulations and analytically combined to predict potential new properties for a Ni 63% - Al 37% martensitic alloy combined with B2 NiAl, shown to be an …

Parental Divorce, Parental Conflict Dimensions, Perception Of Gains, Growth, And Parent-Child Relationship In College Students, Matthew M. Welsh

Open Access Dissertations

The primary focus of this study was to examine the possible associations among perceptions of pre-divorce parental conflict, perceived gains of parental divorce, posttraumatic growth, and current relationship quality with parents. The literature review focuses on college student development, empirical studies related to negative and positive outcomes for children, adolescents, and college students of divorce, and factors related to negative and positive outcomes for children, adolescents, and college students of divorce. Findings are based on data I collected from 430 participants from Purdue University. I addressed my questions and tested the associated hypotheses through the use of MANOVA and hierarchical …

The Structure-Function Relationship Of Intermetallic Compound Catalysts For Light Alkane Dehydrogenation, Zhenwei Wu

Open Access Dissertations

Better utilization of fossil fuels with less emissions is crucial to meet the energy and environmental needs in the near future. The unprecedented revolution of shale gas production in the past decade motivates development of gas-to-liquid fuels technique starting with light alkane dehydrogenation. For better design of catalytic light alkane dehydrogenation, this dissertation synthesizes a wide range of new catalysts including intermetallic nanoparticles formed between Pd-In, Pt-In, Pt-Zn, Pt-Mn and solid solutions formed between Pt-Cu. Emerging techniques in situ Synchrotron X-ray Diffraction, in situ Difference X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering are developed and/or applied to characterize the …

Functional Analysis Of Er-Localized Ubac2 And Ubac2-Interacting Proteins From Arabidopsis, Zhe Wang

Open Access Dissertations

Selective autophagy targets specific cargo by autophagy receptors through interaction with ATG8 (autophagy-related protein 8)/MAP1LC3 (microtubule associated protein 1 light chain 3) for degradation in the vacuole. Here, we report the identification and characterization of three related ATG8-interacting proteins (AT1G17780/ATI3A, AT2G16575/ATI3B and AT1G73130/ATI3C) from Arabidopsis. ATI3 proteins contain a WxxL LC3-interacting region (LIR) motif at the C terminus required for interaction with ATG8. ATI3 homologs are found only in dicots but not in other organisms including monocots. Disruption of ATI3A does not alter plant growth or development but compromises both plant heat tolerance and resistance to the necrotrophic fungal pathogen …

Analytical Methods For Structured Matrix Computations, Xin Ye

Open Access Dissertations

The design of fast algorithms is not only about achieving faster speeds but also about retaining the ability to control the error and numerical stability. This is crucial to the reliability of computed numerical solutions. This dissertation studies topics related to structured matrix computations with an emphasis on their numerical analysis aspects and algorithms. The methods discussed here are all based on rich analytical results that are mathematically justified. In chapter 2, we present a series of comprehensive error analyses to an analytical matrix compression method and it serves as a theoretical explanation of the proxy point method. These results …

The Dark Side Of High-Quality Lmx: Relational Tensions And Their Impacts On Leaders And Members, Lusi Wu

Open Access Dissertations

As one of the most popular approaches to study leadership, the leader-member exchange (LMX) theory focuses on the dyadic relationship between a leader and a member (Gerstner & Day, 1997; Graen & Uhl-Bien, 1995). It posits that supervisors develop different forms of exchange relationships with followers (Sparrowe & Liden, 1997). Low quality LMX is more like economic exchange based on mutually agreed on duties, while high quality LMX is characterized by trust, support, loyalty, and commitment (Uhl-Bien & Maslyn, 2003). Past LMX studies have documented and supported many positive outcomes for high-quality LMX subordinates, such as higher job satisfaction, organizational …

Investigating Airflow Distribution And Contaminant Transport In Commercial Aircraft Cabins, Ruoyu You

Open Access Dissertations

Overhead gaspers are prevalently installed in aircraft cabins as a personalized ventilation system. The air distribution in cabins with gaspers on is crucial for creating a thermally comfortable and healthy cabin environment. This study aims to model the air distribution and contaminant transport in commercial aircraft cabins with gaspers on.

This study first conducted experimental measurements of airflow distribution in a mockup of half of a full-scale, one-row, single-aisle aircraft cabin with a gasper on. Particle image velocimetry (PIV) was used to measure the complex airflow field above a human simulator. This investigation then used the measured data to evaluate …

Tuning Thermal Transport In Thin Films, Yuqiang Zeng

Open Access Dissertations

Decades of research have enabled new understanding of thermal transport at the nanoscale. Leveraging this new understanding to tune heat conduction in thin films (TFs) is of significant interest for both fundamental and applications. This work explores tuning thermal conduction in TFs by structuring, strain engineering, and annealing. Specifically, three approaches are interrogated: 1) nanostructuring to achieve significant in-plane thermal conduction anisotropy in TFs; 2) strain engineering of thermal conductivity (k) of a basic structure in flexible electronics, Au-on-polyimide films, and a representative 2D material, graphene; and 3) high temperature annealing of reduced graphene oxide (RGO) films to enhance k. …

Characterization Of The Human Dead-Box Rna Helicase Ddx5, Zheng Xing

Open Access Dissertations

Gene expression in eukaryotes is highly complex. The central player in gene expression is the messenger RNA (mRNA). After transcription, the mRNA is bound by numerous RNA binding proteins to form a messenger ribonucleoprotein complex (mRNP) that dictates the function and fate of the messengers. Proper mRNP formation is critical for gene expression. DEAD-box proteins are the largest class of RNA helicases that play fundamental roles in RNA and RNP structure remodeling. However, the precise biological roles of the vast majority of them are not well described. To fill in this gap, my research focused on the characterization of the …

Mapping Underground Utilities With Complex Spatial Configurations Using Ground Penetrating Radar, Chenxi Yuan

Open Access Dissertations

Records of the locations, measures, and properties of over 20 million mileage underground utility networks in the US are incomplete, inaccurate, and many times unavailable. This lack of information of underground pipes and cables is a primary reason for over six million of utility interruptions every year that cause injuries, fatalities, property damages, and environmental pollutions, amounting to over eight billions of dollars in loss. It also poses a critical challenge to maintaining and upgrading the ageing underground infrastructure with a D+ score according to the American Society of Civil Engineers’ Report Card. There is a critical need for accurately …

Anisotropic Flow And Fiber Orientation Analysis Of Preimpregnated Platelet Molding Compounds, Drew E. Sommer

Open Access Dissertations

Process modeling of prepreg platelet molded composites (PPMC) is of interest for enabling optimized design of PPMC structures. The platelet mesoscale and the part scale are on the same order, which introduces several modeling challenges including the treatment of variability. The fiber length and concentration results in anisotropic rheological behavior during processing. Current commercial flow simulation tools do not include anisotropic constitutive models and utilize second order orientation tensor methods for the fiber orientation which requires significant interpretation to inform a structural model. A flow and fiber orientation model to predict the final orientation state in molded parts should treat …

Efficient Fast Computing For U-Statistics Via A-Optimal Subsampling, Mingao Yuan

Open Access Dissertations

U-statistics has been widely studied and used in both statistics and machine learning. One challenge in application of U-statistics is the intensively demanding computation. In this thesis, we propose subsampling method to fast compute U-statistics. Our work is fourfold: (1) we formally accommodate uniform subsampling to fast computing of U-statistics; (2) we propose A-optimal subsampling method, which outperforms uniform subsampling method in terms of MSE; (3) we provide a method to approximate the A-optimal subsampling probabilities, since the running time of the A-optimal subsampling probabilities is the same as the full sample U-statistics; (4) we get the limiting distribution of …

Study Of The Nano-Structured Materials For Energy Conversion And Storage Devices, Fan Yang

Open Access Dissertations

Two major parts consist of my work in this dissertation which are the study of the materials for fuel cell catalysts and lithium-ion battery cathodes,

In the first part, FeOF is studied as a new generation cathode material due to its high specific capacity. To overcome its weaknesses which are low conductivity and poor cycle life, graphene sheets are introduced into FeOF to form a FeOF/graphene hybrid. It has been found that introducing graphene sheets can greatly improve the reversibility of FeOF and improve the specific capacity and rate performance by increasing its electronic conductivity. The cycle life and columbic …

Postsecondary Stem Paths Of High-Achieving Students In Math And Science: A Longitudinal Multilevel Investigation Of Their Selection And Persistence, Soohyun Yi

Open Access Dissertations

This study used a quantitative approach to investigate high-school students’ talent-development pathways in STEM from 10th through 12th grades and for 8 years thereafter. The purpose of this study was to longitudinally investigate three important choices and accomplishments on the STEM talent development trajectory: a) selecting a STEM major in college; b) persisting with the STEM major until graduation; and c) selecting a career in STEM after college graduation. Given that students with gifts and talents are more likely to persist and succeed in STEM fields than average achievers, and understanding their unique needs may be the first important task …

A Comprehensive Analysis Of Estimating Land Use Change Emissions Induced By Global Aviation Biofuels Production Using Economic Equilibrium Models, Xin Zhao

Open Access Dissertations

This dissertation is comprised of three independent but closely related essays, which provide new insights on estimating biofuels induced land use (ILUC) change and related emissions from distinct perspectives. The first essay in this dissertation developed the framework for estimating aviation biofuels induced land use change emissions using GTAP-BIO and its coupled emission model, AEZ-EF. We translate International Energy Agency (IEA) projections into appropriate shock sizes by region and pathway. We make modifications in GTAP-BIO to introduce the aviation biofuels pathways and update AEZ-EF based on new data. Twelve aviation biofuels pathways, produced using four technologies including Hydroprocessed Esters and …