Digital Commons Network^™

A Complete Characterization Of Near Outer-Planar Graphs, Tanya Allen Lueder Genannt Luehr

Doctoral Dissertations

A graph is outer-planar (OP) if it has a plane embedding in which all of the vertices lie on the boundary of the outer face. A graph is near outer-planar (NOP) if it is edgeless or has an edge whose deletion results in an outer-planar graph. An edge of a non outer-planar graph whose removal results in an outer-planar graph is a vulnerable edge. This dissertation focuses on near outer-planar (NOP) graphs. We describe the class of all such graphs in terms of a finite list of excluded graphs, in a manner similar to the well-known Kuratowski Theorem for planar …

Differences In Leadership Behaviors Of Principals And Success In The School Turnaround Processes, Annette Lee

Doctoral Dissertations

The purpose of this study was to examine leadership behaviors of principals associated with public elementary schools that were either in the school turnaround process or had already transitioned out of school academic turnaround from 2011 through 2016. Transformational leadership guided the study to determine whether leadership behaviors differed among leaders of schools associated with academic failure. School accountability data were initially gathered through the Louisiana Department of Education website. Academically unsuccessful schools (AUS) were identified. Schools that were deemed failing at least one time during the 2012-2016 timeframe were grouped as follows: (a) Group A consisted of two schools …

Aiming For Success: Evaluating Statistical And Machine Learning Methods To Predict High School Student Performance And Improve Early Warning Systems, David Alexandro

Doctoral Dissertations

In response to the high school dropout crisis, which comes with great economic and social costs, early warning systems (EWSs) have been developed to systematically predict and improve student outcomes. The purpose of this study is to evaluate different statistical and machine learning methods to predict high school student performance and improve EWSs. By improving education EWSs, this study aims to better identify those students in need of targeted support and inform on-the-ground practitioners who may intervene long before students may be dropping out.

The current study explores the aforementioned methods in the context of a cohort of 40,008 Connecticut …

Data Sampling And Reasoning: Harnessing Optimization And Machine Learning For Design And System Identification, Pei Cao

Doctoral Dissertations

The recently rapid advancements in sensing devices and computational power have caused paradigm shift in engineering analyses: data driven and sampling-based approaches play more and more important roles. For example, with sampling-based global optimization techniques, mechanical components can be refined and redesigned; system parameters can be accurately identified. With advancements in data mining and machine learning, underlying input and output relations of complex systems can be developed to make predictions with unseen data or to expedite analytical process. In this dissertation, advanced optimization and machine learning techniques are developed and employed to multi-facet engineering tasks from system design to identification. …

Mesoscale Modeling Of Short Fatigue Crack Behavior In Metallic Microstructure And Application To The Structural Components, Hao Yuan

Doctoral Dissertations

Many catastrophic failures of metallic structures were found to originate from fatigue damages in local details. Meanwhile, the associated environmental effects such as corrosion and high uncertainties from many aspects including material microstructure also make it difficult to quantify the fatigue life of the components or structures. Partially overcoming the limitation of current experimental means and custom fatigue assessment methods, this dissertation develops a probabilistic multi-scale fatigue damage modeling framework to comprehensively analyze the short fatigue crack behavior in mesoscale microstructure and propagate the damage to component level and structural level analysis.

For statistical volume element (SVE) in mesoscale, a …

Advanced Control Design For Power Capture Enhancement And Load Mitigation Of Wind Turbines, Yuan Yuan

Doctoral Dissertations

Wind energy is commonly recognized as a major environmentally friendly renewable energy source. Modern wind turbines are large, flexible structures that may suffer from reduced life owing to extreme loads and fatigue when operated under highly turbulent wind field. In this dissertation, advanced controllers are synthesized to reduce overall cost of wind energy production by regulating power capture and at the same time decreasing the structural loading to enhance the durability of turbine components.

First, collective pitch control (CPC) methods are investigated to regulate speed and power, and to mitigate symmetric loads in high wind speeds. A new adaptive control …

Relative Age Effects And Measures Of Potential In The Primary Grades, Rebecca O'Brien

Doctoral Dissertations

In education, relative age effects (RAE) are present if a student’s age when compared to that of his/her classmates has implications for scores on measures of achievement and performance. Researchers studying relative age have established significant, but inconsistent effects of being relatively older or younger in a grade level on measures of achievement. Test results are used to identify students’ needs for educational services and interventions, and the effects of relative age could influence a student’s access to these academic supports. This study used the Early Childhood Longitudinal Study, Kindergarten Class of 2010-11 (ECLS-K:2011) dataset to investigate the strength and …

Investigations Of The Effects Of Reading Skill And Epistemological Beliefs On Learning In General Chemistry, And How Students Use Textbooks To Study, Rene Buell

Doctoral Dissertations

Understanding how student characteristics affect learning in chemistry can influence the pedagogical strategies employed by chemistry instructors. Previous studies have investigated the effects of characteristics including prior knowledge, math ability, and motivations on course performance. Student characteristics can also influence study strategies employed by students. Few studies, however, have focused on the role of language and reading comprehension skill on learning in chemistry, and fewer have investigated the levels of epistemological beliefs of general chemistry students. Three studies are presented in this dissertation. In the first study, the effects of prior knowledge and reading comprehension skill on learning from reading …

Unitarily Invariant Norms On Finite Von Neumann Algebras, Haihui Fan

Doctoral Dissertations

John von Neumann’s 1937 characterization of unitarily invariant norms on the n × n matrices in terms of symmetric gauge norms on Cn had a huge impact on linear algebra. In 2008 his results were extended to Ifactor von Neumann algebras by J. Fang, D. Hadwin, E. Nordgren and J. Shen. There already have been many important applications. The factor von Neumann algebras are the atomic building blocks from which every von Neumann algebra can be built. My work, which includes a new proof of the Ifactor case, extends von Neumann’s results to an arbitrary finite von Neumann algebra on …

The Effect Of Ionospheric Conductivity On Magnetospheric Dynamics, Benjamin Joseph Jensen

Doctoral Dissertations

The connection between ionospheric conductivity and the dynamics of the magnetosphere was investigated, using several methods to change the ionospheric conductivity and then study the resultant changes to the magnetosphere. Computer simulations of the Earth's geospace environment were utilized using OpenGGCM coupled with an ionosphere model CTIM and a ring current model RCM.

Three methods were used to modify ionospheric conductivity. The incoming particle precipitation was modified by several orders of magnitude $\alpha=.01,.1,1,10$, the ionospheric conductivity was increased or decreased by factors $\beta=.25, .5, 1, 2,$ and $4$, and for the last method differing values of $F_{10.7}$, $70,110, 150, 200,$ …

Investigating The Functions Of Two Transcription Factors In Vascular Development And Wall Biosynthesis In Arabidopsis Thaliana, Qian Du

Doctoral Dissertations

Plant vascular system is important for plant growth and development. There are three different cell types in vascular tissues, xylems, phloems and procambial or cambial. In the presence of cambium, plants continuously generate new vascular tissues. During the differentiation process, xylem fibers develop lignified secondary cell walls which provide abundant resources for biofuel industry. However, the underlying mechanisms of vascular development and secondary cell wall formation are still elusive. Our objectives are to identify new transcription factors function in vascular initiation and biomass deposition in Arabidopsis. In this thesis, we identified two activation-tagging mutants, hva-d with high vascular activity …

Bayesian Variable Selection With Applications To Neuroimaging Data, Shariq Mohammed

Doctoral Dissertations

In this dissertation, we discuss Bayesian modeling approaches for identifying brain regions that respond to certain stimulus and use them to classify subjects. We specifically deal with multi-subject electroencephalography (EEG) data where the responses are binary, and the covariates are matrices, with measurements taken for each subject at different locations across multiple time points. EEG data has a complex structure with both spatial and temporal attributes to it. We use a divide and conquer strategy to build multiple local models, that is, one model at each time point separately both, to avoid the curse of dimensionality and to achieve computational …

The Relationship Of Physical Activity Participation On Executive Functions And Stress Regulation Among Youth In Poverty, Jesse Mala

Doctoral Dissertations

Individuals living in poverty are exposed to greater amounts of adversity, resulting in greater levels of circulating stress hormones. Elevated levels of stress hormones are associated with a plethora of negative health outcomes including the early onset of diabetes, heart disease, and impaired brain development and executive functions. Deficits in executive functions can result in detrimental health, education and life outcomes among school-aged youth. Conversely, physical activity participation have been shown to improve executive functions among youth. Therefore, the purpose of this study was to examine if physical activity participation is related to greater executive functions and stress regulation among …

Advances In The Analysis Of Incomplete Data Using Multiple Imputations, Ruochen Zha

Doctoral Dissertations

While Multiple Imputation (MI) has become one of the most broadly used methods for handling incomplete data, many questions remain unanswered regarding statistical inference when MI is used with incomplete data. One such question is how to calculate statistical power. Although it is widely acknowledged that MI improves estimation efficiency, reduces estimation bias, and partially restores power loss, there is a gap in the literature as far as quantifying the power gained from using MI over complete case analysis (CCA). Furthermore, the rates of missing information are well developed for traditional MI, but not for newly-adjusted MI. This thesis presents …

Higher-Order Accurate Finite Difference Method For Thermal Analysis In Double-Layered Solid Structures -- Gradient Preserved Method, Yun Yan

Doctoral Dissertations

Layered structures have appeared in many systems such as biological tissues, micro-electronic devices, thin films, fins, reactor walls, thermoelectric power conversion, thermal coating, metal oxide semiconductors, and thermal processing of DNA origami nanostructures. Analyzing heat transfer in layered structures is of crucial importance for the design and operation of devices and the optimization of thermal processing of materials. There are many numerical methods dealing with the layered structures or interface problems. The existing numerical methods such as the immersed interface method and the matched interface boundary method, if using threegrid points across the interface, usually provide only a second-order truncation …

Wastewater Pipe Condition And Deterioration Modeling For Risk-Based Decision-Making, Greta J. Vladeanu

Doctoral Dissertations

The dissertation research work described here has four primary objectives: (1) the development of a comprehensive wastewater pipe condition rating model that incorporates a large number of environmental, structural, and hydraulic parameters of the pipe; (2) the development of a wastewater pipe deterioration model used to predict future overall condition states of the pipe, as well as determining the probability of failure at any given age of the pipe; (3) the development of a comprehensive consequence of failure model that assesses the consequence of wastewater pipe failure using economic, social, and environmental cost factors; and (4) the development of a …

Development And Analysis Of Engineered Brain Cell Microenvironments Mimicking Healthy And Diseased Neuronal Circuits, Kahla St. Marthe

Doctoral Dissertations

Astrocytes and microglia (glial cells) are active elements of the brain maintaining numerous homeostatic functions. Disturbances result in worsening of neuro-inflammation, traumatic brain injury, and various stages of brain tumors. Glial cells contribute to homeostasis for dynamic second messengers in the CNS, including intracellular calcium concentration ([Ca2+] i). Calcium is a central secondary messenger which signals for example, through the N-methyl-D-aspartate (NMDA) glutamate receptor on the neuronal membrane. A large, dynamic Ca2+ influx ensues after glutamate binds to the NMDA receptor. This influx initiates several molecular mechanisms within the cell. Disturbances in calcium homeostasis can lead to neurological diseases such …

Validation Of Spatial Hysteresis As The Internal Damping Mechanism In An Unmanned Micro Aerial Vehicle Model, Ashleigh Chambers

Doctoral Dissertations

Unmanned aerial vehicles have been an area of interest in both research and industry for the past several decades. Advancements in technology have allowed such aircraft to decrease in size. UAVs are less expensive than traditional aircraft and are less restricted in where they can fly due to their compact size, leading to shifts in the way infrastructure, agriculture, and transportation surveillance and operations are handled.

However, small aerial vehicles and flexible, composite ones are more susceptible to crashes. This has led to an increased interest in methods to control such aircraft. In order to accurately model for a composite, …

Smoothed Particle Hydrodynamics For Computational Fluid Dynamics, Wennan Ma

Doctoral Dissertations

Smoothed particle hydrodynamics (SPH) is a simple and effective numerical method that can be used to solve a variety of challenging problems in computational mechanics. It is a Lagrangian mesh-free method ideal for solving deformation problems. In the SPH method, the state of a system is represented by a set of particles, which possesses individual material properties and interact with each other within a specific range defined as a support domain by a weight function or smoothing function. SPH features flexibility in handling complex flow fields and in including physical effects.

In theory, the basic concept of the SPH method …

Three-Dimensional Imaging, Visualization And Recognition In Low Light Environments, Adam Markman

Doctoral Dissertations

There has been significant research in developing novel image sensors to capture a scene in low illumination environments. Using conventional passive imaging sensors that operate in the visible spectrum, camera read-noise becomes higher than the signal information from the scene resulting in read-noise dominant images. These images suffer from poor signal-to-noise ratio making scene visualization unobtainable. Thus, imaging in photon-limited environments has been viewed as a nuisance. This dissertation will consist of three separate parts that discuss utilizing photon-counting principals for secure information storage or imaging in photon-limited environments. First, an optical security system for information storage is introduced that …

Applications Of Non-Classical Logic, Andrew Tedder

Doctoral Dissertations

Archival abstract submitted

Functional Inequalities For Hypoelliptic Diffusions Using Probabilistic And Geometric Methods, Phanuel Mariano

Doctoral Dissertations

We study gradient bounds and other functional inequalities related to hypoelliptic diffusions. One of the key techniques in our work is the use of coupling of diffusion processes to prove gradient bounds. We also use generalized $\Gamma$-calculus to prove various functional inequalities. In this dissertation we present two research directions; gradient bounds for harmonic functions on the Heisenberg group, and gradient bounds for the heat semigroup generated by Kolmogorov type diffusions.

For the first research direction, we construct a non-Markovian coupling for Brownian motions in the three-dimensional Heisenberg group. We then derive properties of this coupling such as estimates on …

Social-Epistemic Agency, Hanna Gunn

Doctoral Dissertations

In this dissertation, I argue for a unifying account of epistemic and communicative injustice. I do this by showing how these are both ultimately threats to our agency. More specifically, I argue that they are threats to our social-epistemic agency, a distinct kind of agency concerned with the ability to be self-determining in the social-epistemic domain. This agency is fundamentally valuable given the importance of being treated as someone worthy of inclusion in communicative and epistemic life. I argue that agency should be conceived of as a measure of our ability to actually bring about changes in the social-epistemic …

Synthesis And Modeling Of Ferroelectric Nanocomposites, Yomery Espinal

Doctoral Dissertations

Nanocomposites consisting of a ferroelectric oxide embedded within a non-ferroelectric matrix are a unique class of materials with potential to improve performance in next-generation electronics and non-volatile memory. Dielectric losses and breakdown due to processing and intrinsic properties of a monolithic ferroelectric point to low figures of merit. Therefore, it is necessary to develop composite materials with an active ferroelectric that is physically confined within a low-loss dielectric matrix while maintaining significant dielectric and pyroelectric properties inherent to ferroelectrics. The purpose of this work is to explore the behavior of ferroelectric nanocomposites as a function of dimensionality, and composition. The …

Entropy As A Method For Identifying Treatment Resistant Autism Spectrum Disorder, Nathan Wright

Doctoral Dissertations

Background: Individuals diagnosed with Autism Spectrum Disorder (ASD) experience lifelong challenges which can impact peer relationships, adaptive functioning, and independent living. Verbal intelligence has proven to be the strongest indicator of outcomes and responsiveness to behavioral intervention, but this property only stabilizes in children between 6 and 8 years of age. Behavioral treatment is the primary intervention for individuals diagnosed with ASD, but it is most effective when delivered as an early intervention strategy for toddlers and very young children. A biomarker which could distinguish treatment resistant subgroups of ASD from would allow for the development and implementation of alternative …

New Evidence On The Environmental Impacts Of Driving Restrictions And Other Government Policies, Zheng Liu

Doctoral Dissertations

Studies using time-series regression discontinuity (RD) designs find no effect of Mexico City's driving restriction but an increase in car ownership after the restriction, while studies using difference-in-differences (DD) methods have shown the effectiveness of similar restrictions in other cities. Development literature has shown a wage shock for white-collar workers in Mexico during the same period, which may encourage initial car purchases among white-collars and confound the results from time-series RD. To control the wage shock, this study applies a DD method with unrestricted days and days after the restriction as a two-way control. It finds that Mexico City's program …

A Numerical Investigation Of Multiple Traveling Pulse And Front Solutions, Faisal Duraihem

Doctoral Dissertations

ABSTRACT

Algorithms are proposed to calculate traveling pulses and fronts in both directions

for the FitzHugh- Nagumo equations in one dimensional spatial domain. The rst

algorithm is based on the application of the steepest descent method to a certain

functional on some admissible sets. These sets are dierent for pulses and for fronts.

This approach is global in nature, so that an initial guess for the wave prole and the

speed can be quite dierent from the correct solution. The second algorithm is the

pseudo arc length continuation method, which solves the governing equations directly.

The two algorithms are complementary. …

Operationalizing Recovery From Substance Use Disorders Among Adolescents In High School, Yiyun Chen

Doctoral Dissertations

The term “recovery” has been widely adopted in substance use-related literature. But no operational standard can be found regarding how to measure recovery among substance use population under 18 years old. Using data from 294 adolescents who were followed for 12 months after receiving treatment for substance use disorders (SUDs), we find converging evidence of a general recovery factor v, extracted from 15 indicators, that potentially reflects adolescents’ level of recovery from SUDs. The latent v score generated using factor loadings is associated with criterion variables in the expected directions where positive correlations were found with for life satisfaction, …

Exploring Targets Of Transcription Factors In Cancer Signaling Pathways, Tham Hong Hoang

Doctoral Dissertations

Recent studies have suggested a key role of activities related to target genes of transcription factors (TFs) in cancer signaling pathways. Molecular pathway curation includes mostly upstream signals which are well-established in the literature, but the activities that are downstream of TFs are not well understood. The purpose of this thesis is to design a computational method for exploring TF target genes in a given molecular pathway. We then use this data to stratify patients and relate TF activity to patient survival.

Transcriptome data can provide a detailed readout of events taking place within a cancer, but new computational tools …

Advances In Smart Structure Technologies For Civil Infrastructure, Sergio Lobo-Aguilar

Doctoral Dissertations

Smart civil engineering structures incorporate electronic devices to generate information that can be used for enhancing their own performance and/or the performance of other related systems. Three main components can be typically integrated with a structural system in order to generate a smart structure: sensing and sensor networks, data processing and decision-making, and actuation and control. This dissertation contributes to the state of the art of smart structural technologies for civil infrastructure through investigations on each one of these areas. For the area of sensing and sensor networks, fieldwork on structural health monitoring (SHM) was performed. In particular, it was …