Digital Commons Network^™

Characterization Of Nanomaterials For Thermal Management Of Electronics, Amit Rai

Doctoral Dissertations

Recently, there has been a growing interest in flexible electronic devices as they are light, highly flexible, robust, and use less expensive substrate materials. Such devices are affected by thermal management issues that can reduce the device’s performance and reliability. Therefore, this work is focused on the study of the thermal properties of nanomaterials and the methods to address such issues. The goal is to enhance the effective thermal conductivity by adding nanomaterials to the polymer matrix or by structural modification of nanomaterials. The thermal conductivity of copper nanowire/polydimethylsiloxane and copper nanowire/polyurethane composites were measured and showed more than threefold …

Effective Magnetic And Electric Response Of Composite Materials, Mona Hassan Alsaleh

Doctoral Dissertations

Metamaterials (MMs) are nanocomposite materials consisting of metal-dielectric resonators much smaller in size than the wavelength of the incident light. Common examples of metamaterials are based on split ring resonators (SRRs), parallel wires or strips and fishnet structures. These types of materials are designed and fabricated in order to provide unique optical responses to the incident electromagnetic radiation that are not available in naturally existing materials. The MMs can exhibit unusual properties such as strong magnetism at terahertz (THz) and optical frequencies. Additionally, negative index materials (NIMs) can provide negative index of refraction which can be used in many applications …

Electrical Characterization Of Graphene And Nanodiamond Nanostructures, A Z M Nowzesh Hasan

Doctoral Dissertations

The electrical characterization on two-dimensional carbon-based graphene and nanodiamond materials was performed to improve charge transport properties for the label-free electrical biosensors. The charge transport in solution-gated graphene devices is affected by the impurities and disorders of the underlying dielectric interface and its interaction with the electrolytes. Advancement in field-effect ion sensing by introducing a dielectric isomorph, hexagonal boron nitride between graphene and silicon dioxide of a solution-gated graphene field-effect transistor was investigated. Increased transconductance due to increased charge carrier mobility is accompanied with larger ionic sensitivity. These findings define a standard to construct future graphene devices for biosensing and …

Nanoparticle Catalytic Enhancement Of Carbon Dioxide Reforming Of Methane For Hydrogen Production, Nicholas Groden

Doctoral Dissertations

The U.S. produces 5559.6 million metric tons of carbon dioxide annually, of which 21% is produced by industrial processes. Steam reforming, an industrial process that accounts for 95% of all hydrogen production in industry, produces 134.5 million metric tons of carbon dioxide or around 11% of the total carbon dioxide produced by industry. This carbon dioxide is then either emitted or goes through a sequestration process that accounts for 75% of the plant's operational costs. An alternative reaction to steam reforming is dry reforming, which utilizes carbon dioxide rather than emitting it and can be used in conjunction with current …

Understanding Why Students Take Industry-Based Credentialing Examinations: Instrument Development And Pilot Study, Jennifer H. Lawrence

Doctoral Dissertations

Educational credentialing is complicated for students with the addition of industry-based credentialing (IBC) in traditional academic and career and technical fields (Bahr, 2015; Lumina Foundation, 2015; Xu & Ran, 2015). Human Capital Theory and Cognitive Engagement Theory framed this study which looked at IBC training from the student point of view (Grisham, 2013; Saldana, 2016; Walters, 2004). The body of literature on credential training is sparse and largely focused on institutional policy rather than student perception and participation (Bahr, 2015; Xu & Ran, 2015). There is evidence that salaries are positively correlated with IBCs and studies show that employers pay …

Multidimensional Feature Engineering For Post-Translational Modification Prediction Problems, Norman Mapes Jr.

Doctoral Dissertations

Protein sequence data has been produced at an astounding speed. This creates an opportunity to characterize these proteins for the treatment of illness. A crucial characterization of proteins is their post translational modifications (PTM). There are 20 amino acids coded by DNA after coding (translation) nearly every protein is modified at an amino acid level. We focus on three specific PTMs. First is the bonding formed between two cysteine amino acids, thus introducing a loop to the straight chain of a protein. Second, we predict which cysteines can generally be modified (oxidized). Finally, we predict which lysine amino acids are …

The Effects Of Pair Budget Goal Difficulty And Pair Identity On Decision-Making And Performance, Chaoping Li

Doctoral Dissertations

Mixed incentive compensation structures have been widely studied in the accounting literature (e.g., Tian et al. 2017; Dekker et al. 2012, Rothenberg 2011; Hwang et al. 2009). However, the findings in the literature as to the effectiveness of mixed incentives are not consistent. The inconsistency in the mixed incentives literature may be due to the various levels of social dilemma embedded in the research setting of the studies. Therefore, I experimentally investigated two factors that may reduce the embedded social dilemma issue and improve the effectiveness of mixed incentive compensation. In this study, student participants were assigned to pairs to …

Electromagnetic Wave-Matter Interactions In Complex Opto-Electronic Materials And Devices, Raj Kumar Vinnakota

Doctoral Dissertations

This dissertation explores the fundamentals of light-matter interaction towards applications in the field of Opto-electronic and plasmonic devices. In its core, this dissertation attempts and succeeds in the the modeling of light-matter interactions, which is of high importance for better understanding the rich physics underlying the dynamics of electromagnetic field interactions with charged particles. Here, we have developed a self-consistent multi-physics model of electromagnetism, semiconductor physics and thermal effects which can be readily applied to the field of plasmotronics and Selective Laser Melting (SLM). Plasmotronics; a sub-field of photonics has experienced a renaissance in recent years by providing a large …

Engineered Coating Of Natural Fibers And Oil-Water Interfaces With Self-Assembly Of Clay Nanotubes, Abhishek Panchal

Doctoral Dissertations

Taking into consideration two different types of surfaces, this dissertation proposes techniques to coat the surface of natural fibers and oil-water interfaces by spontaneous self-assembly of halloysite clay nanotubes. The material of choice, halloysite clay, is a widely available natural resource and can be used after minimal processing. In regards to chemical composition, halloysite clay resembles aluminosilicate mineral kaolin; physically, a defect in the crystal structure ordering causes the sheets of kaolinite to roll into halloysite nanotubes. The dimensions of halloysite nanotubes are dependent on the source, but generally vary from 200 nm to 3 µm in length, 100-150 nm …

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 …

The Influence Of Regional Stereotypes In Employee Selection, Brittani E. Plaisance

Doctoral Dissertations

An individual’s social world is understood through categorizing other people as those within an individual’s own in-group and those without, or the out-group. Social cognitive theory suggests that individuals make decisions in social settings based on implicit social comparisons between these groups. Stereotypes are oversimplified beliefs about the members of a specific group and discrimination is the behavioral outcome based on held stereotypes. Discrimination based on race, ethnicity, age, and gender has dominated research in the realm of employee selection for the last twenty years. Researchers have demonstrated perceived and actual differences in various attributes by region of the United …

Development Of A Longitudinal Imaging System For Murine Brain Injury Models, Chelsea D. Pernici

Doctoral Dissertations

Following traumatic brain injury (TBI) and stroke, secondary injury cascades can lead to axonal damage and persistent microglia activation, respectively, in subcortical regions of mice. Current techniques, such as diffusion tensor imaging (DTI) and histology are used to observe features related to damage, but DTI lacks cellular resolution and histology is conducted on fixed tissue, preventing longitudinal studies in the same mouse. The combination of cranial windows and multiphoton microscopy (MPM) is used to image cells in the upper layers of the mouse cortex, but resolution rapidly degrades with imaging depth, making it difficult to observe white matter and subcortical …

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 …

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 …

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, …

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 …

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 …

Investigating The Role Of Operating Parameters And Surface Treatments Of Carbon Based Electrodes In Capacitive Deionization, Md Ashique Ahmed

Doctoral Dissertations

This research focused on studying salt ion removal behavior and regeneration of electrodes used in capacitive deionization (CDI). CDI is a novel deionization technology that utilizes electrochemical processes to extract ions from water and either hold them electrostatically on the electrode surface or trap them in a double layer formed next to surface of electrodes. The use of porous carbon materials as electrodes in CDI enhances ion removal capacity because of availability of high surface area, conductivity, porosity, non-corrosive behavior, and other favorable properties. Experiments were conducted with a synthetic NaCl solution prepared in the laboratory. The first part of …

The Effect Of Horizontal Inequity, Capacity For Budget Slack, And Severity Of Peer Overstatement On Managerial Reporting Behavior, Yiwen Li

Doctoral Dissertations

An ongoing stream of accounting research indicates that non-pecuniary factors significantly affect employees’ reporting behavior. This study investigates the behavioral effects of three non-pecuniary factors - horizontal pay inequity, capacity for budget slack, and severity of peer overstatement. The behaviors of interest are the employees’ level of honesty and whether or not they report a peer that is overstating.

In the experiment, participants acted as division managers who request funding from the owner of a fictitious company to produce certain parts. In each period, participants were paired with a different fictitious peer and were required to make two decisions under …

I See What You Say: Influential Nonverbal Signals Of Frontline Employees On Customer Outcomes, Shuang Wu

Doctoral Dissertations

This research aims to investigate the influential nonverbal signals of frontline employees on customer outcomes. Frontline employees play a vital role in initiating and maintaining customer relationships. The interactions between customers and employees influence not only the immediate reactions, including both affective and cognitive responses, but also customer outcomes, like purchase intention, satisfaction, perceived service quality, and positive word-of-mouth. Both qualitative and quantitative methodologies are employed in this dissertation.

Previous studies examined the effects of employee nonverbal signals on customers’ cognitive responses, but limited research has been done on the affective responses of customers. Affect-based trust, positive affect, negative affect, …

A Model Of The Relationship Between Performance Feedback And Goal Setting: A Consideration Of, Affective Cognitive, And Psychological State Effects, Ann-Marie R. Castille

Doctoral Dissertations

Performance feedback meetings are often dreaded, perceived to be worthless, and de-motivating for employees (Culbertson, Henning, & Payne, 2013; Rock, 2008). Although they are intended to enhance motivation and performance (Erez, 1977; Kim & Hamner, 1976), over a third of feedback interventions backfire, resulting in lower rather than higher performance (Kluger & DeNisi, 1996). Motivational theories (i.e., behavioral motivation theory, organizational justice theory, reversal theory, goal setting theory, and theory of planned behavior) provide complementary explanations for the impact of feedback on performance. However, these explanations have not been subjected to comprehensive empirical scrutiny. The purpose of this dissertation was …

Automatic Document Summarization Using Knowledge Based System, Andrey Timofeyev

Doctoral Dissertations

This dissertation describes a knowledge-based system to create abstractive summaries of documents by generalizing new concepts, detecting main topics and creating new sentences. The proposed system is built on the Cyc development platform that consists of the world’s largest knowledge base and one of the most powerful inference engines. The system is unsupervised and domain independent. Its domain knowledge is provided by the comprehensive ontology of common sense knowledge contained in the Cyc knowledge base. The system described in this dissertation generates coherent and topically related new sentences as a summary for a given document. It uses syntactic structure and …

Mutual Information In The Frequency Domain For Application In Biological Systems, Rui Liu

Doctoral Dissertations

Biological systems are comprised of multiple components that typically interact nonlinearly and produce multiple outputs (time series/signals) with specific frequency characteristics. Although the exact knowledge of the underlying mechanism remains unknown, the outputs observed from these systems can provide the dependency relations through quantitative methods and increase our understanding of the original systems. The nonlinear relations at specific frequencies require advanced dependency measures to capture the generalized interactions beyond typical correlation in the time domain or coherence in the frequency domain. Mutual information from Information Theory is such a quantity that can measure statistical dependency between random variables. Herein, we …

Three Essays On Information-Securing In Organizations, Yaojie Li

Doctoral Dissertations

This dissertation is intended to interpret, analyze, and explain the interplay between organizational structure and organizational information systems security by mapping structural contingency theory into three qualitative studies. The research motivation can be attributed in two ways. First, Johnson and Goetz's (2007) conception of embedding information in organizations as part of their field research interviewing security executives serves as a methodological inspiration for the series of three studies reported here. The point that security should be infused into organization activities instead of serving as a "bolted-on" function is a central tenet guiding the development of this dissertation. Second, a macro …

Engineering Tools To Further Neuroscientific Investigation, Jessica L. Scoggin

Doctoral Dissertations

Custom equipment is often necessary in the laboratory. However, costs for such equipment can be high and efficient systems with lower cost are an advantage. In this work, we showed that a cellular environment to keep cells healthy and viable for five hours on a microscope could be created using FDM printing (Chapter 3). Design criteria were that it maintained correct temperature, high humidity and proper pH to control the environment as discussed in Chapter 2. Results indicated that cells would maintain viability for up to five hours, but redesigns needed to be made for extending viability past five hours. …

Cost-Effective Use Of Follow-Up Colonoscopies And Fecal Immunochemical Tests In Colorectal Cancer Screening, Grace N. Joseph

Doctoral Dissertations

Colorectal cancer (CRC), if not detected early, can be costly and detrimental to one's health. Screening techniques for colorectal cancer can help find and remove adenomas in an effort to prevent future CRC. A colonoscopy has the potential of identifying CRC early as well as preventing the disease. Fecal Immunochemical Tests (FITs) is an initial non-invasive screening technique that identifies the presence of the disease, and needs to be followed by a more invasive test (like colonoscopy) if anything is detected. However, the optimal frequency for follow-up colonoscopy, and screening colonoscopy with FITs is unknown, and may vary based on …