Digital Commons Network^™

Formulation To Application: Thermomechanical Characterization Of Flexible Polyimides And The Improvement Of Their Properties Via Chain Interaction, Alejandro Rivera Nicholls

USF Tampa Graduate Theses and Dissertations

In this work, Polyimides were synthesized by incorporating an aromatic diamine monomer with a methylene linker, 4,4'-methylenebis(2,6-dimethylaniline) (MBDMA), to make a robust main chain along with aliphatic polyetherdiamine backbone linkers to reduce rigidity. The polymers were designed to exhibit thermal properties in between those of conventional aromatic polyimides and polymers with wholly aliphatic ether diamine links. Through dynamic mechanical analysis and differential scanning calorimetry, it is shown that control of the molar ratios of the aromatic MBDMA and the composition and size of the aliphatic polyetherdiamine can be used to tune the glass transition temperature. The materials were characterized and …

Phasor Measurement Unit Data-Based Steady State And Dynamic Model Estimation, Anas Almunif

USF Tampa Graduate Theses and Dissertations

Phasor measurement units (PMUs) have been put into power grid for real-time monitoring. This research investigates the PMU data for steady state estimation and dynamic model estimation. It focuses on three main research areas to enhance the security of the power system monitoring. First, optimal PMU placement (OPP) problem is developed to minimize the number of PMUs required for the system to be completely observable using mixed integer linear programming and nonlinear programming. Second, PMU measurements are ranked for oscillation monitoring based on two approaches: oscillation mode observability and Prony analysis. Further, the principles, multi-channel data handling, and noise resilience …

Effects Of Reservoir Conditions And Trace Co-Contaminant Gases On Geological Carbon Sequestration, Ram Kumar

USF Tampa Graduate Theses and Dissertations

Geological carbon sequestration in a saline formation is a promising technology for large-scale carbon dioxide (CO2) mitigation. Several factors such as temperature, pressure, salinity, hydraulic conductivity, and mineralogy of a formation affect the CO2 sequestration in saline formations. These factors can vary widely depending upon the type of formation or the degree of heterogeneity within a formation. In addition to these properties of the repositories, the CO2-rich flue gas streams captured from point sources often contains small amounts of impurities such as sulfur oxides (SOx) and nitrogen oxides (NOx), which may have serious implications on the chemistry of the repositories …

Evaluating Conversation Agent Impact On Student Experience In A Distance Education Course, Grover Walters

USF Tampa Graduate Theses and Dissertations

We explore the efficacy of conversation agents operating as an instructional aid in a distance education course. Two aspects of efficacy are considered—conversation agent impact on student perceptions of the experience, and how different design features of the agent affect student perceptions of engagement. Evaluation of the agent is accomplished by collecting data from 24 undergraduate participants separated into random groups. We conduct two rounds of mixedmethod evaluation. Between the two rounds, a modification to the agent occurs based on the outcome of the first evaluation. Findings include limitations related to phrasing and data persistence features of the design that …

Fabrication And Characterization Of Electrical Energy Storage And Harvesting Energy Devices Using Gel Electrolytes, Belqasem Aljafari

USF Tampa Graduate Theses and Dissertations

Redox-active materials in the bulk of gel electrolytes are unquestionably holding the primary roles in developing energy harvesting and storage technology. Both technologies are necessary in order to cope with the current challenges of the environmental crises of global warming and finite non-renewable sources while the demand for energy modern societies have been speedily increased. One of the most challenges of making a hybrid device of energy conversion and storage is the cost of the fabrication process. Therefore, gel electrolyte-based materials with redox-active properties can potentially be a promising solution to improve the performance of electrochemical and photoelectrochemical devices for …

Simulation And Experimental Investigation Of Fluid Mixing Enhancement With Orifice Plate, Mohammed Al Busaidi

USF Tampa Graduate Theses and Dissertations

Current experimental and simulation fluid mixing studies aim to increase mixing efficiency and incorporate various measurement methods to quantify mixing. In this thesis, comprehensive simulation and experimental studies were carried out to investigate the effects of an orifice plate on mixing. Mixing efficiency is measured through the correlation of volume fraction to color light reflectivity, as dyes were introduced to the fluids being mixed. Volume fractions close to 0.5 indicate high mixing performance, and the efficiency declines as volume fractions depart from 0.5. It was found that fluids in a small diameter tube do not mix due to the absence …

Desertification Risk Analysis Based On Soils And Climate In Olive Cultivated Areas In Tulare County, California, Zehra Kavakli Karatas

USF Tampa Graduate Theses and Dissertations

Desertification is one of the most critical environmental problems caused by human activities and climate change. As a result of human activities, land degradation has been seen in many agricultural areas. Intense pressure on cultivated fields causes loss of soil fertility, which can then lead to desertification. Planting plant drought-resistant plants, such as olives, is one strategy for reducing desertification risk in cultivated areas. It is essential to find a way not only how to combat this process but also how to adapt or survive with desertification conditions. Defining desertification risks have a fundamental role in combating drought. The goal …

Boron Variation And The Subducted Sediment Component In The Volcanics From The Bifurcated Portion Of The Lesser Antilles Island Arc (Laia), Ami Margret Ngo Ward

USF Tampa Graduate Theses and Dissertations

North of Martinique island the Lesser Antilles volcanic arc bifurcates, creating a double arc. Here volcanic activity has migrated up to 50 km westward with time, resulting in two volcanic lines that are distinct in age. The eastern line, commonly referred to as the old arc, was active from Early Eocene to Mid-Miocene (Nagle, 1971; Nagle et al., 1976; Westercamp and Tazieff, 1980; Andreieff et al., 1988). The western line, commonly referred to as the recent arc, has been active since the late Pliocene, ~6 Ma ago (Nagle, 1971; Nagle et al., 1976; Westercamp and Tazieff, 1980; Andreieff et al., …

Measuring And Utilizing High-Dimensional Information Of Optical Fields, Ziyi Zhu

USF Tampa Graduate Theses and Dissertations

Currently, many areas of optical techniques including imaging, inspection and communication emphasize the utilization of the high-dimensional information encoded in optical fields. There is also a requirement for novel measurement techniques to extract this high-dimensional information with high-speed and accuracy. We firstly introduce a scan-free direct measurement technique that is capable of simultaneously characterizing the amplitude and phase of a coherent scalar optical field. Our direct measurement approach is constituted of a weak polarization perturbation which is followed by the recording of a polarization-resolving imaging process. The weak perturbation rotates the linear polarization on the spatial frequency domain of the …

Detection Of Gender-Related Differential Item Functioning (Dif) In The Mathematics Subtests In Turkey, Zeynep Merve Sapmaz

USF Tampa Graduate Theses and Dissertations

The main goal of this study was to investigate differential item functioning by gender in the Fundamental Mathematics (FMS) and Mathematics subtests (MS) of the MSPC-2018 Higher Education Institutions Examination. Each test consists of 40 items and for both subtests random samples of 10.000 students were received from the MSPC separately. To compare non-IRT (Classical Test Theory) and Item Response Theory (IRT) approaches, Cochran-Mantel-Haenszel (C-M-H), Logistic Regression (LR), and 2-PL IRT-LR statistics were used.

For the FMS, C-M-H, LR, and 2-PL IRT-LR procedures identified 18, 16, and 10 out of 40 items that had DIF, respectively. Based on the non-IRT …

Fractional Random Weighted Bootstrapping For Classification On Imbalanced Data With Ensemble Decision Tree Methods, Sean Charles Carter

USF Tampa Graduate Theses and Dissertations

Ensemble methods are commonly used for building predictive models for classification. Models that are unstable to perturbations in the training set, such as the decision tree, often see considerable reductions in error when grouped, using bootstrapped resamples of the training data to train many models. The non-parametric bootstrap, however, has limited efficacy when used on severely imbalanced data, especially when the number of observations of one or more classes is exceptionally small. We explore the fractional random weighted bootstrap, which randomly assigns fractional weights to observations, as an alternative resampling pro cedure in training machine learning ensembles, particularly decision tree …

Can Florida's Springs Coast Provide A Potential Refuge For Calcifying Organisms? Evidence From Benthic Foraminifera, Kyle E. Amergian

USF Tampa Graduate Theses and Dissertations

Florida’s Springs Coast, located in the northeast Gulf of Mexico, includes an extensive system of salt marshes that discharge millions of liters of fresh water into coastal waters daily. The chemical properties of the spring waters include high alkalinity and high calcium concentrations due to the Paleogene limestone lithology of this region of Florida. Benthic foraminifers, which are recognized as ecologically important bioindicators, occur abundantly on the shallow shelf off the Springs Coast. Based on the prevalence of the benthic foraminifer Archaias angulatus in the seagrass beds along this shallow shelf, a previous study proposed that the Springs Coast provides …

Understanding The Influence Of The Cancer Microenvironment On Metabolism And Metastasis, Shonagh Russell

USF Tampa Graduate Theses and Dissertations

Cancer is a complex and heterogeneous disease. Not only is there considerable variability between different cancer types, but there is enormous variability between and within patients who have the same type of cancer. Within tumors, there are multiple cell types, including cancer cells, stromal cells, and immune cells. The tumor microenvironment often induces the healthy cells to become pro-tumorigenic. Cell metabolism is exquisitely sensitive to changes in the tumor microenvironment and can be measured to infer the aggressiveness of cancer and predict response to therapy. In this dissertation, we aim to understand how the microenvironment, specifically low pH, affects the …

Enhancing Secrecy And Capacity Of Wireless Systems Using Directive Communications, Mohammed A. Hafez

USF Tampa Graduate Theses and Dissertations

The emerging advances in wireless communications make it an essential component of our everyday life. Moreover, the current research aims towards involving wireless communications in health monitoring applications, which helps medical personnel to remotely keep track of the development of the condition of their patients. Such information is considered highly sensitive and may cause significant harm if acquired by an adversary. The wireless environment has a broadcast type of nature, where the emitted electromagnetic waves spread all over the surrounding area of the transmitting antenna. This broadcast nature raises a considerable concern about the secrecy of this sensitive information while …

Detecting Digitally Forged Faces In Online Videos, Neilesh Sambhu

USF Tampa Graduate Theses and Dissertations

We use Rossler’s FaceForensics dataset of 1004 online videos and their corresponding forged counterparts [1] to investigate the ability to distinguish digitally forged facial images from original images automatically with deep learning. The proposed convolutional neural network is much smaller than the current state-of-the-art solutions. Nevertheless, the network maintains a high level of accuracy (99.6%), all while using the entire FaceForensics dataset and not including any temporal information. We implement majority voting and show the impact on accuracy (99.67%), where only 1 video of 300 is misclassified. We examine why the model misclassified this one video. In terms of tuning …

A Study On The Influence Of Instructional Mentors On Novice Teachers In High-Needs Schools, Dodi Palkovic Davenport

USF Tampa Graduate Theses and Dissertations

Within the first five years of new teachers’ employment, between 30 and 50 percent leave the profession (Smith &Ingersoll, 2004). High levels of teacher attrition are associated with negative effects on student achievement (Strong, 2005). In an effort to retain teachers and improve the quality of the teaching workforce, many states and local school districts require new teachers to enroll in induction and mentoring programs. This study is part of a larger program evaluation of one public school district’s new teacher induction program. The purpose of this investigation was to determine how a novice teacher perceives the influence of a …

Evaluating The Evidence Base For Evidence-Based Instructional Practices In Chemistry Through Meta-Analysis, Md Tawabur Rahman

USF Tampa Graduate Theses and Dissertations

Investigating the effectiveness of instructional practices provides an evidence base to inform instructional decisions. Synthesizing research studies on instructional effectiveness provides an estimate of the generalizability of effectiveness across settings, along with an exploration of factors that may moderate the impact, which cannot be achieved within individual studies. This study sought to provide a synthesis of evidence- based instructional practices (EBIPs) particular to chemistry through meta-analysis. 99 studies were analyzed comprising a broader view of chemistry specific studies than past meta-analyses. The results showed that EBIPs feature a demonstrably positive impact on students’ academic performance in chemistry, although assessment topic …

Life History Through The Eyes Of A Hogfish: Evidence Of Trophic Growth And Differential Juvenile Habitat Use, Meaghan E. Faletti

USF Tampa Graduate Theses and Dissertations

Understanding ontogenetic linkages among fish habitats is critical for conservation of fish populations and the ecosystems on which they rely. Natural tags such as stable isotopes are an effective tool commonly used to investigate ecological questions regarding fish movement and habitat use. Here, I analyzed stable isotopes from the sequentially deposited laminae of Hogfish (Lachnolaimus maximus) eye lenses from the eastern Gulf of Mexico (eGOM) to investigate trophic and geographic changes across individual life histories. I documented evidence of entire-life scale trophic growth through increases in δ15N. I also observed depth separation at the juvenile stage, evidenced by variation in …

Thermo-Oxidative Degradation Of Hdpe Geomembranes: Effect Of Phenolic Antioxidant And Hindered Amine Light Stabilizer Concentrations, Yasin Kocak

USF Tampa Graduate Theses and Dissertations

High density polyethylene (HDPE) geomembrane is most common geomembrane which is mainly used for civil engineering applications. However, HDPE geomembrane loses its properties under oxidative degradation progress. This study aims to assess geomembranes which have different percentage of phenolic antioxidant and hindered amine light stabilizer (HALS) with under the six months of the thermal-oxidative degradation. The interactions between phenolic antioxidant, HALS and carbon black can affect the mechanical, physical and chemical properties. To monitor these properties, Differential Scanning Calorimetry (DSC), Fourier-transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM/EDX), Melt Index tests, …

Evaluating The Effect Of Temperature On A Human Parasite And Its Intermediate Snail Host: Implications For A Changing Climate, Karena H. Nguyen

USF Tampa Graduate Theses and Dissertations

Global climate change is impacting the emergence, re-emergence, prevalence, and incidence of infectious diseases worldwide, including parasitic diseases of humans (Blum and Hotez 2018). Neglected tropical diseases, defined as a group of parasitic diseases affecting developing countries in the tropics (Hotez et al. 2007), are of particular concern because these diseases occur in areas that are also expected to experience rapid population growth and agricultural development in the coming decades. As human population and food demand increase, the greater the likelihood of humans encountering intermediate hosts that either inhabit agricultural areas or are impacted by agricultural development, which will influence …

Interactive Fitness Domains In Competitive Coevolutionary Algorithm, Atm Golam Bari

USF Tampa Graduate Theses and Dissertations

Evolutionary Algorithms (EA) have been successfully applied to a wide range of optimization and search problems where no mathematical model of the quality of a candidate solution is available. Interactive Evolutionary Algorithms (IEA) and Competitive Coevolutionary Algorithms (CCoEA) go one step further by being able to tackle problems where the only means to evaluate the quality of a candidate solution is via interactions. In a typical IEA, interactions take place between the solution being evolved and human evaluators. In a CCoEA, interactions take place between solutions themselves, without need for human interaction. This dissertation identifies computer-aided learning as an application …

Fewer Wetlands More Connectivity: Implications Of Land Use-Land Cover Change In An Agricultural Landscape, Stephanie Lawlor

USF Tampa Graduate Theses and Dissertations

St. Lucie County (SLC) is a 1,782 km2 area in east-central Florida that drains to the Nationally Significant Indian River Lagoon (IRL). It is low lying and nearly level, with widespread non-floodplain wetlands (NFWs) and few natural channels. NFWs comprise the vast majority of SLC wetlands, both in terms of numbers and area. Since the early 20th century, SLC has undergone extensive land use-land cover (LULC) change and is now characterized by citrus farming in the interior and municipalities on its eastern coast on the Atlantic Ocean. This LULC change has been made possible by the construction of an extensive …

Energy Transition Modeling: Social And Technical Dynamics Of Moving To Renewable Energy, Lawrence Gottschamer

USF Tampa Graduate Theses and Dissertations

The majority of global electricity is generated using fossil fuels as an energy source, and the science linking fossil fuel combustion with negative environmental impacts is clear. Recognizing this link, decarbonizing the electricity system is a critical component of climate change mitigation. However, moving electricity generation, distribution, and end-use behavior patterns to renewable energy is a complex socio-technical energy transition challenge with a number of economic, policy, technological, societal and environmental barriers. Energy transition work tends to be siloed within these topics; ignoring complex socio-technical interdependencies impacting electricity system transition dynamics. This work fills the knowledge gap with a ‘systems …

Exploring The Equity Performance Of Bike-Sharing Systems With Disaggregated Data: A Story Of Southern Tampa, Zhiwei Chen

USF Tampa Graduate Theses and Dissertations

The rising adoption of bike-sharing systems brings significant benefits to individuals and society as a whole. However, whether these benefits are distributed throughout society in a fair manner is still an open question. This study presents a methodological framework for assessing the equity performance of bike-sharing systems, with Coast Bike Share system in southern Tampa as a case study. The framework integrates three different datasets: bike-sharing infrastructure, individual travel itineraries and individual sociodemographic attribute data. With these datasets, we model individual accessibility to activity locations using bike-sharing as the mode of transportation by analyzing the “walking-cycling-walking” process of a bike-sharing …

Modeling Of Buildings With Electrochromic Windows And Thermochromic Roofs, Hua-Ting Kao

USF Tampa Graduate Theses and Dissertations

Air conditioning and heating have increased substantially during the past two decades. According to a survey, buildings consume about 73% of the total electricity in the United States, accounting for 41% of all other energy in the world. At the same time, building skin technologies are constantly improving. Electrochromic and thermochromic are two exciting new technologies that can help reduce the energy consumption of a building. The purpose of this work is to increase our understanding of how much the use of electrochromic (EC) and thermochromic (TC) technologies can reduce the energy consumption of residential and commercial buildings in two …

Sundaas Story: A Mixed-Methods Study Of Household Sanitation Provisioning In Urban Informal Housing In India, Sarita Vijay Panchang

USF Tampa Graduate Theses and Dissertations

The aims of this research were to examine sanitation insecurity in urban informal housing through the lens of the built environment, social disparities, and health implications. While the Millennium Development Goals for halving the global proportion of people without access to safe drinking water were met ahead of schedule, progress fell short for sanitation, creating new objectives for the Sustainable Development Goals to be met in 2030. Much research in the Global South is dedicated to community-level sanitation promotion, but often presumes a rural rather than urban setting. Urban informal housing settings constitute a unique challenge due to the range …

On Automation Of Code Transformations For Concept Inventory Misconceptions, Dmytro Vitel

USF Tampa Graduate Theses and Dissertations

Identifying common misconceptions held by novice programmers is a primary goalof the Computing Education Research agenda. This thesis proposes to formalize such mis-conceptions through program transformations. We first describe the implementation of theEvoParsons system, that allows students to practice programming skills with the help ofso-called Parsons puzzles. This software serves as a tool for gathering data on how studentsinteract with such puzzles. Our first contribution is the system architecture reorganization:development of Web SPA UI, REST service back-end, hypothesis validation infrastructureand student-UI data collection. We then review and compare several code-transformationtools (ANTLR, Rascal MPL and StrategoXT) and show how they might …

Associations Between Mental Health, Academic Success, And Perceived Stress Among High School Freshman In Accelerated Coursework, Andrew S. Jenkins

USF Tampa Graduate Theses and Dissertations

Youth in accelerated curricula programs are an understudied population in relation to groups who struggle academically. To date, few studies have been conducted examining relationships between psychopathology symptomology, life satisfaction, academic achievement, and perceived stress. To address this, the current study completed a secondary analysis of an archival dataset in order to expand upon previous research into the predictive relationships between mental health (psychopathology and life satisfaction; beginning of year) and students’ subsequent academic achievement and perceived stress (assessed mid-year). Furthermore, the current study investigated the predictive effects of mid-year academic achievement (course grades) and perceived stress on students’ subsequent …

A Communication-Centric Framework For Post-Silicon System-On-Chip Integration Debug, Yuting Cao

USF Tampa Graduate Theses and Dissertations

System-on-Chip (SoC) plays an important role in people’s everyday life. These systems are often deployed in critical applications, bugs discovered after their deployment in field can be extremely expensive, resulting in catastrophic loss of company revenues, compromise of personal and national security, and even human life. Post-silicon debug is a critical component of the validation of modern microprocessors and SoC designs. A major challenge in post-silicon debug is the severely limited observability where only a small number of debug interface signals are available to observe a vast space of internal executions of SoC designs. This dissertation addresses the above issues …

Students' Perceptions On Alternative Break Experiences And Selecting An Academic Major In A Four-Year College, Bianny Fernández Collado

USF Tampa Graduate Theses and Dissertations

Research shows that 50-80% of college students are exploratory/undecided or appear as declared and will change their major at least once. Although higher education institutions have developed and implemented several initiatives to assist students with selecting an academic major, students are struggling to reach this milestone. According to Gebhard (2015), real-world and experiential opportunities successfully prepare students to select an academic major. Thus, the purpose of this qualitative exploratory study is to describe in-depth a phenomenon: how a service-based experience, offered through an Alternative Breaks (aB) program may prepare student participants for the selection of an academic major. The study …