Digital Commons Network^™

Continuous-Flow Synthesis Of Fine Chemicals And Pharmaceutical Compounds Over Intelligent Organocatalysts With Bifunctional Reactivity, Abdo-Alslam Alwakwak

Doctoral Dissertations

“Many biological systems that utilize organic active sites to catalyze reactions under mild conditions invoke cooperative catalytic pathways, whereby two or more active sites work together to activate the reactant(s). The use of cooperative (bifunctional) catalysts and continuous flow chemistry (a reaction within the narrow channels of a micro‐ or microfluidic reactor) are commonplace in sustainable chemical transformation and attract a great deal of interest with respect to economic and environmentally-sustainable production of fine chemicals, pharmaceuticals, and agrochemicals, water treatment, as well as upgrading of biomass feedstocks. Although, some methods have been developed for immobilization of bifunctional catalysts for cooperative …

System Efficient Esd Design Concept For Soft Failures, Giorgi Maghlakelidze

Doctoral Dissertations

"This research covers the topic of developing a systematic methodology of studying electrostatic discharge (ESD)-induced soft failures. ESD-induced soft failures (SF) are non-destructive disruptions of the functionality of an electronic system. The soft failure robustness of a USB3 Gen 1 interface is investigated, modeled, and improved. The injection is performed directly using transmission line pulser (TLP) with varying: pulse width, amplitude, polarity. Characterization provides data for failure thresholds and a SPICE circuit model that describes the transient voltage and current at the victim. Using the injected current, the likelihood of a SF is predicted. ESD protection by transient voltage suppressor …

Structurally And Electronically Diverse Polyanion-Based Cathode Materials For Alkali-Ion Batteries, Prashanth Sandineni

Doctoral Dissertations

”Through this investigation polyanion-based cathode materials including sulfates, phosphates, and phosphites of transition metal have been synthesized for lithium and sodium-ion batteries and their electrochemical performances were evaluated. The emphasis was on soft chemical routes to discover metastable phases which are often missed in high temperature synthesis. Iron-based compounds were the main focus of this investigation, however, concurrently a few vanadium-analogues of iron compounds were investigated to evaluate the effect of multi-electron process on achievable voltage and capacity.

This investigation resulted in the discovery of several compounds with unique crystal structures, namely AFe₃(SO₄)₂(OH)_{6 …}

Transition Metal Chalcogenide Hybrid Systems As Catalysts For Energy Conversion And Biosensing, Siddesh Umapathi

Doctoral Dissertations

"Generation of hydrogen and oxygen through catalyst-aided water splitting which has immense applications in metal air batteries, PEM fuel cells and solar to fuel energy production, has been one of the critical topics in recent times. The state of art oxygen evolution reaction (OER), oxygen reduction reaction (ORR), hydrogen evolution reaction (HER) catalysts are mostly comprised of precious metals. The current challenge lies in replacing these precious metal-based catalysts with non-precious earth-abundant materials without compromising catalytic efficiency.

This research explores mixed metal selenides containing Fe-Ni, Fe-Co and RhSe which were hydrothermally synthesized and/or electrodeposited and tested for OER and ORR …

Enhanced Electrochemical Performance Of Li-Ion Battery Cathodes By Atomic Layer Deposition, Yan Gao

Doctoral Dissertations

”Li-ion battery now plays an irreplaceable role in supplying green and convenient energy. In this work, atomic layer deposition (ALD) was used to modify Li-ion battery cathode particles for performance enhancement.

An ultrathin and conductive CeO₂ ALD film was deposited on Li-rich layered cathode particles, of which the specific capacity and cyclic stability were significantly improved. On the same cathode particles, FeO_x ALD and post-annealing resulted in a stable and conductive surface spinel phase to improve the performance.

Synergetic TiN coating and Ti doping were performed on a LiFePO₄ (LFP) cathode and extended its cycle life. The …

Deep Learning For Digitized Histology Image Analysis, Sudhir Sornapudi

Doctoral Dissertations

“Cervical cancer is the fourth most frequent cancer that affects women worldwide. Assessment of cervical intraepithelial neoplasia (CIN) through histopathology remains as the standard for absolute determination of cancer. The examination of tissue samples under a microscope requires considerable time and effort from expert pathologists. There is a need to design an automated tool to assist pathologists for digitized histology slide analysis. Pre-cervical cancer is generally determined by examining the CIN which is the growth of atypical cells from the basement membrane (bottom) to the top of the epithelium. It has four grades, including: Normal, CIN1, CIN2, and CIN3. In …

Attention Mechanism In Deep Neural Networks For Computer Vision Tasks, Haohan Li

Doctoral Dissertations

“Attention mechanism, which is one of the most important algorithms in the deep Learning community, was initially designed in the natural language processing for enhancing the feature representation of key sentence fragments over the context. In recent years, the attention mechanism has been widely adopted in solving computer vision tasks by guiding deep neural networks (DNNs) to focus on specific image features for better understanding the semantic information of the image. However, the attention mechanism is not only capable of helping DNNs understand semantics, but also useful for the feature fusion, visual cue discovering, and temporal information selection, which are …

Decolonizing Education: Using Mother Tongue And English Side By Side In Nigeria, Omobola Wusu

Doctoral Dissertations

Nigerians lack access to effective mother tongue education (MTE) at all levels of their schooling. It is well established that cognitive and educational benefits are achieved if one’s mother tongue (MT) is used as the medium of education. This study aimed to determine how adult Nigerians around the world who had been deprived of using their mother tongues (MTs) in their education reflect on their past experiences with negative messages or colonial language ideologies received in school. Also, it explored how these past experiences have shaped their positive MT identities, their MT experiences, and their perspectives on MTE. In this …

An Integrated Flow-Curing Model For Predicting Residual Stresses In Textile Composites, Weijia Chen

Doctoral Dissertations

Fiber-reinforced composites have been widely employed in structural applications due to their high stiffness-to-weight ratio and easily-tailored mechanical properties. However, manufacturing of these lightweight materials involves an infusion and curing process, and flow-induced defects and residual stresses can easily occur, which can compromise the mechanical performance of the composite structures. The purpose of this work is to develop an integrated flow-curing processing model to accurately predict the resin flow front and the residual stresses in the Liquid Composite Molding (LCM) process. In the infusion model, the fiber fabrics are treated as a homogeneous and porous material, and the resin flow …

Exploiting Memristors For Compressive Sensing Applications, Fengyu Qian

Doctoral Dissertations

The amount of sensory signal is increasing dramatically as we’re stepping into the era of Internet of Things (IoT). Compressive Sensing (CS), feature as Sub-Nyquist sampling rate and low complexity sensing architectures, is very promising for these kinds of applications where resources are restricted. Through applying this novel compression technology, data size of sensory signals are largely compressed such that it is very efficient within the signal processing, data transmitting and storage processes. Compared to conventional codec method, CS technique requires less hardware resources and achieve lower power consumption within sensor nodes.

However, there are several bottle-necks of existing compressive …

Inequity And Resistance: Latinx Students And The College Readiness Process, Israel Velez

Doctoral Dissertations

This qualitative study used Youth Participatory Action Research and Community Cultural Wealth Framework (Yosso, 2005) to understand how Vamos a La Universidad (VALU), a high school bilingual college preparation program, impacts first-generation Latinx ninth grade students’ community cultural wealth and understanding about college. This study expands our understanding of how Latinx students interpret the college preparation process after participating in a college preparation program and emphasizes the importance of students’ cultural background and social contacts in their college readiness process. This study proposes new initiatives to add to Latinx students’ college learning process and increase the students’ interest in continuing …

Asymptotic Analysis Of Quasi-Limiting Behavior For Drifted Brownian Motion Conditioned To Stay Positive, Sangjoon Lee

Doctoral Dissertations

A Quasi-Stationary Distribution for a Markov process with an almost surely reached absorbing state is a conditionally time-invariant distribution on the state space, which the condition is that the process is not absorbed by the given time. Previous works of Martinez et al. identify the family of Quasi-Stationary Distribution for Brownian motion with negative drift, and characterize the domain of attraction for each of them.

This paper will mainly focus on two subjects.

1. We provide a new approach simplifying the existing results, which explains the direct relation between a QSD and an initial distribution in the domain of attraction …

Topological Data Analysis For Clustering And Classifying Time Series, Renjie Chen

Doctoral Dissertations

Topological Data Analysis (TDA), which refers to methods of utilizing topological

features in data (such as connected components, tunnels, voids, etc.) has gained considerable

momentum. More recently, TDA has been increasingly used for analyzing time

series. The recent researches of using TDA in time series are mainly focused on unsupervised

and supervised learning. In this thesis, a review of TDA will be provided,

following by using TDA in time series for doing unsupervised and supervised learning

for different applications.

Insurance Analytics With Tree-Based Models, Zhiyu Quan

Doctoral Dissertations

Tree-based models are supervised learning algorithms broadly described by repeated partitioning of the regions of the explanatory variables to form homogeneous groups. The partitioning is based on minimization of a loss function related to the response variable. The results form and create a tree-based structure, which helps make for better model interpretation, for predicting the response. Because of the many advantages of tree-based models, their use in disciplines like engineering, biostatistics, and ecology has been a popular alternative predictive tools for building classification and regression models. A single decision tree may not produce accurate predictions, thereby, we also examine the …

Cybersecurity Games: Mathematical Approaches For Cyber Attack And Defense Modeling, Mohammad Hadi Valizadeh

Doctoral Dissertations

Cyber-attacks targeting individuals and enterprises have become a predominant part of the computer/information age. Such attacks are becoming more sophisticated and prevalent on a day-to-day basis. The exponential growth of cyber plays and cyber players necessitate the inauguration of new methods and research for better understanding the "cyber kill chain," particularly with the rise of advanced and novel malware and the extraordinary growth in the population of Internet residents, especially connected Internet of Things (IoT) devices.

Mathematical modeling could be used to represent real-world cyber-attack situations. Such models play a beneficial role when it comes to the secure design and …

Perceptions Of Physics Teachers In Singapore About Curriculum Sequencing, Lay Lean Fong

Doctoral Dissertations

Curricular sequencing is central to instruction design and enactment. If carefully planned for, the order of topics to be taught would determine how the fundamentals of the discipline can be presented and introduced to learners, in a sequence that eases them into more complex ways of reasoning and thinking about the domain. These sequences or learning progressions often reflect the experts’ conceptual schemas of the discipline and are conceived as strategic models for instruction (Duschl et al., 2011).

The varied findings from current research on learning progressions underscore the complexity of teaching and learning, and imply that even ‘well-crafted’, standards-based, …

African American Female Law Enforcement Officers' Lived Experiences And Mentoring: A Thematic Narrative, Harold Wilson

Doctoral Dissertations

Black female officers are an underrepresented sub-group of the law-enforcement profession. The bulk of research on women’s policing has focused on the growth of women in law enforcement, barriers, sexual harassment, gender differences, why women are deterred from law enforcement, physical limitations, and instruments used during the recruitment process, and the stress endured after entry into the profession. When looking at Black female officers’ lived experience and perceptions around mentoring; research is lacking. Eight Black female officers from the San Francisco Bay Area participated in this study. Findings revealed that all of the women have faced a recurring sense of …

Towards Embedded System Hardware Security Design And Analysis, Yanping Gong

Doctoral Dissertations

Security in embedded system design, which has long been a critical problem for ensuring the confidentiality, data integrity and system reliability for embedded system designers and users, is now facing a new dimension of threat from the attacks on hardware. As the IC design reaches sub-micron regime, increased sensitivity of device under environmental condition has made some new types of attacks possible, while the analysis and detection for design vulnerabilities against these attacks are harder on the much more complicated designs nowadays. In the meanwhile, more efficient and diverse attack methodologies are developed by attackers as the technology advances. On …

From King Solomon To Ian Smith: Rhodesian Alternate Histories Of Zimbabwe, Edward Guimont

Doctoral Dissertations

In the eleventh century CE, the Shona people of Central Africa built the city of Great Zimbabwe, an administrative center and royal home. Connected to the Indian Ocean gold trade, it would become the largest pre-colonial city in sub-Saharan Africa. However, it entered into decline and was ultimately abandoned by the sixteenth century – when the first Portuguese expeditions came in contact with the region. The fact that this city entered into decline just as Europeans encountered it set it up to become the center of a number of fantastical legends about its origins, typically linking it with the Biblical …

Differences In Creativity Across Domains Between Students With Dyslexia And Those Without, Maria Avitia

Doctoral Dissertations

When a student has a learning disability in reading and or dyslexia, interventions focus on remediating the weakness. Positive psychology is a field of psychology that looks to help people, based on harnessing a person's strengths, to create better outcomes. Strengths-based or asset-based interventions have been used with people with developmental disabilities to learn new skills. This study hoped to help identify strengths for people with dyslexia in two areas that have been hypothesized to be strengths for them: creativity and visual-spatial ability. Creativity has typically been assessed with domain-general measures rather than actual measures of creativity. Similarly, visual-spatial ability …

E-Hailing Pricing And Strategies For Transportation System Performance Improvement, Qixing Wang

Doctoral Dissertations

App-based e-hailing ride services, which connect both drivers and riders through their GPS-enabled mobile devices, have rapidly developed into a viable transportation alternative for many travelers. This technology has changed the set of choices for travelers and has shifted travel patterns, most significantly away from traditional taxi services. These applications provide convenience and flexibility to both drivers and passengers, however, they have also caused several issues. For example, they have pulled ridership off public transportation, damaged the taxi industry, and created new congestion etc. during their expansion. In this research, we analyze available information to arrive at a solution to …

Adaptive Feature Engineering Modeling For Ultrasound Image Classification For Decision Support, Hatwib Mugasa

Doctoral Dissertations

Ultrasonography is considered a relatively safe option for the diagnosis of benign and malignant cancer lesions due to the low-energy sound waves used. However, the visual interpretation of the ultrasound images is time-consuming and usually has high false alerts due to speckle noise. Improved methods of collection image-based data have been proposed to reduce noise in the images; however, this has proved not to solve the problem due to the complex nature of images and the exponential growth of biomedical datasets. Secondly, the target class in real-world biomedical datasets, that is the focus of interest of a biopsy, is usually …

Feature Space Modeling For Accurate And Efficient Learning From Non-Stationary Data, Ayesha Akter

Doctoral Dissertations

A non-stationary dataset is one whose statistical properties such as the mean, variance, correlation, probability distribution, etc. change over a specific interval of time. On the contrary, a stationary dataset is one whose statistical properties remain constant over time. Apart from the volatile statistical properties, non-stationary data poses other challenges such as time and memory management due to the limitation of computational resources mostly caused by the recent advancements in data collection technologies which generate a variety of data at an alarming pace and volume. Additionally, when the collected data is complex, managing data complexity, emerging from its dimensionality and …

Dual Purpose Tunable Vibration Isolator Energy Harvester: Design, Fabrication, Modeling And Characterization, S. M. Mahdi Mofidian

Doctoral Dissertations

This dissertation is focused on design, fabrication, characterization, and modeling of a unique dual purpose vibration isolation energy harvesting system. The purpose of the system is to, simultaneously, attenuate unwanted vibrations and scavenge kinetic energy available in these vibrations. This study includes theoretical modeling and experimental work to fully characterize and understand the dynamic behavior of the fabricated dual purpose system. In the theoretical study, both numerical (Runge-Kutta) and analytical (Harmonic Balance Method, HBM) methods are used to obtain the dynamic behavior of the system. The system features a combination of mechanical and electromagnetic components to facilitate its dual functionality. …

A Multicarrier Technique For Monte Carlo Simulation Of Electrothermal Transport In Nanoelectronics, Tyler J. Spence

Doctoral Dissertations

The field of microelectronics plays an important role in many areas of engineering and science, being ubiquitous in aerospace, industrial manufacturing, biotechnology, and many other fields. Today, many micro- and nanoscale electronic devices are integrated into one package. e capacity to simulate new devices accurately is critical to the engineering design process, as device engineers use simulations to predict performance characteristics and identify potential issues before fabrication. A problem of particular interest is the simulation of devices which exhibit exotic behaviors due to non-equilibrium thermodynamics and thermal effects such as self-heating. Frequently, it is desirable to predict the level of …

Gully Erosion And Holocene-Anthropocene Environmental Change In Southern New England, Megan Hill

Doctoral Dissertations

The proposed Anthropocene epoch provides a novel framework for recognizing, measuring, and interpreting human impacts to landscapes around the world. Important also, is the need to place human impacts in the context of how these landscapes have been behaving over recent geologic time (i.e., the Late Pleistocene and Holocene). In southern New England, widespread Anthropocene landscape changes occurred throughout 17^th-20^th century following European settlement. Markers of these Anthropocene landscape changes are visible in high-resolution topographic data in the form of historic land use features (e.g., stone walls and charcoal hearths), in gullies that dissect hillslopes, and in …

Collective Behavior In Dissipative Systems: Flocking & Futbol, Maurici López-Felip

Doctoral Dissertations

Collective behavior and large-scale group dynamics have become especially hot topics of research in the physical, biological, and cognitive sciences — from microscopic interactions involving the signaling and collective response of bacteria, to the types of coordination dynamics that are present in team sports. Recent findings argue for a fundamental principle for the self-organization of activity that is indifferent to scale; and that the behavior manifest in both living and non-living collectives serves to satisfy the dissipation of energy and strives toward the maximization of entropy production. While undoubtedly provocative, this hypothesis opens up new avenues of inquiry for the …

The Impact Of Estradiol And Stress On Spatial Memory, Soniya Assudani Patel

Doctoral Dissertations

Spatial memory is a critical cognitive function that involves for navigating, interpreting, and representing environments, planning a route, remembering the location of an object or event, and understanding spatial configurations. The three studies presented are original investigations on how estradiol, anxiety, and stress influence hippocampal-dependent spatial memory. The first study assessed the impact of estradiol level on spatial memory in young adult women. Salivary assays were obtained to determine the exact estradiol level. Women at the high and low estradiol phases of their natural menstrual cycle were compared to each other and to women on oral contraceptives (OCs). Behavioral performance …

On The Topic Of Spatial Capture-Recapture Modeling, Paul Mclaughlin

Doctoral Dissertations

Over the past two decades there have been many advancements in modeling capture-recapture (CR) data to account for emerging data collection technology and techniques. Spatial capture-recapture (SCR) models have been introduced to estimate population size and numerous other demographic parameters from spatially explicit CR data. Here we offer a comprehensive review of the development of CR modeling up to and including SCR models.

We then introduce a new SCR model which allows for attractions between individuals via their daily movements. A simulation study is used to demonstrate accounting for these attractions can improve population size estimation. Additionally, we apply our …

Unpredictability, Social Beliefs, And Neural Dynamics, Natasza Marrouch

Doctoral Dissertations

Archival abstract submitted