Engineering Commons^™

Photocatalytic Reduction Of Co2 With Tunable Bandgap And Bandedge Materials, Thuhuong T. Ngo

USF Tampa Graduate Theses and Dissertations

Solar energy is a sustainable resource which has substantial potential to meet the increasing demand for renewable energy. Though there has been some success in harvesting solar energy for electricity production, converting solar energy to chemical energy as fuels is still a challenge due to low efficiency.

Since the discovery of TiO₂ photocatalysts for splitting water (4) and reducing CO₂ (5) to form useful chemical feedstock such as H₂, CO and CH₄, much research has been done to increase the efficiency of photocatalysts. However, the current conversion efficiency of photocatalysts remains low (~5%) (6, …

Reduced Dimensionality Effects In Gd-Based Magnetocaloric Materials, Hillary Faith Belliveau

USF Tampa Graduate Theses and Dissertations

Magnetic refrigeration based on the magnetocaloric effect (MCE) is a promising alternative to conventional gas compression based cooling techniques. Understanding impacts of reduced dimensionality on the magnetocaloric response of a material such as Gadolinium (Gd) or its alloys is essential in optimizing the performance of cooling devices, which is also the overall goal of this thesis. We have determined, in the first part of the thesis, that laminate structures of pure Gd produced by magnetron sputtering have several disadvantages. The target material (pure Gd), ultra-high vacuum components, and the electrical energy it takes to run the manufacturing process are all …

Improved 2d And 3d Resistivity Surveys Using Buried Electrodes And Optimized Arrays: The Multi-Electrode Resistivity Implant Technique (Merit), Henok Gidey Kiflu

USF Tampa Graduate Theses and Dissertations

This thesis presents a novel resistivity method called Multi-Electrode resistivity technique (MERIT) that is used for high resolution imaging of complex geologic features at depth and near the edges of survey lines. The MERIT electrodes are especially shaped and designed to be self-driven using a robust-direct push technique. Measurements are taken using optimized arrays that are generated using a modified version of the “Compare-R” optimization algorithm. This work focused on both two-dimensional (MERIT2D) and three-dimensional (MERIT3D) applications of the buried array and show the relevance of the additional information gained by the addition of deep electrodes especially in sites with …

Confinement Effects And Magnetic Interactions In Magnetic Nanostructures, Kristen Lee Stojak Repa

USF Tampa Graduate Theses and Dissertations

Multifunctional nanocomposites are promising for a variety of applications ranging from microwave devices to biomedicine. High demand exists for magnetically tunable nanocomposite materials. My thesis focuses on synthesis and characterization of novel nanomaterials such as polymer nanocomposites (PNCs) and multi-walled carbon nanotubes (MWCNTs) with magnetic nanoparticle (NP) fillers.

Magnetite (Fe₃O₄) and cobalt ferrite (CoFe2O4) NPs with controlled shape, size, and crystallinity were successfully synthesized and used as PNC fillers in a commercial polymer provided by the Rogers Corporation and poly(vinylidene fluoride). Magnetic and microwave experiments were conducted under frequencies of 1-6 GHz in the presence of …

Towards Computational Human Behavior Modeling For Just-In-Time Adaptive Interventions, Tylar Murray

USF Tampa Graduate Theses and Dissertations

The advent of powerful wearable devices and smartphones has enabled a new generation of “in-the-wild” user studies, adaptive behavioral intervention strategies, and context measurement. Though numerous proof-of-concept studies continue to push the limitations of what a behavioral scientist can do with these technologies, there remains a major methodological roadblock separating behavioral theory and application. Avatar-user interaction theory, for example, is not well defined in its formulation, and thus guidelines for intervention designers depend on heuristic methods and designer intuition. Computational modeling has been slow to move into behavioral science in general, but a growing population of behavioral scientists recognize this …

Optimal Demand Response Models With Energy Storage Systems In Smart Grids, Mohemmed Masooud Alhaider

USF Tampa Graduate Theses and Dissertations

This research aims to develop solutions to relieve system stress conditions in electric grids. The approach adopted in this research is based on a new concept in the Smart Grid, namely, demand response optimization. A number of demand response programs with energy storage systems are designed to enable a community to achieve optimal demand side energy management.

The proposed models aim to improve the utilization of the demand side energy through load management programs including peak shaving, load shifting, and valley lling. First, a model is proposed to nd the optimal capacity of the battery energy storage system (BESS) to …

Novel Magnetic Nanostructures For Enhanced Magnetic Hyperthermia Cancer Therapy, Zohreh Nemati Porshokouh

USF Tampa Graduate Theses and Dissertations

In this dissertation, I present the results of a systematic study on novel multifunctional nanostructure systems for magnetic hyperthermia applications. All the samples have been synthesized, structurally/magnetically characterized, and tested for magnetic hyperthermia treatment at the Functional Materials Laboratory of the University South Florida. This work includes studies on four different systems: (i) Core/shell Fe/γ-Fe₂O₃ nanoparticles; (ii) Spherical and cubic exchange coupled FeO/Fe₃O₄ nanoparticles; (iii) Fe₃O₄ nano-octopods with different sizes; (iv) High aspect ratio FeCo nanowires and Fe₃O₄ nanorods.

In particular, we demonstrated the enhancement of the heating …

Pepper Mild Mottle Virus As A Surrogate For Enteric Viruses: Implications For Assessing Water Quality, Erin Michelle Symonds

USF Tampa Graduate Theses and Dissertations

Less than 10% of the world’s domestic wastewater is disinfected prior to discharge into surface waters; therefore, human exposure to diverse wastewater-related pathogens results in millions of cases of illness each year. Among the enteric pathogens, viruses represent an important group of emerging pathogens and are frequently the cause of food- and water-borne outbreaks of illness. Although the World Health Organization and many government agencies mandate the use of bacterial indicators to identify poor microbial water quality, it is well known that these indicators poorly correlate with fecal pollution contamination events and risk of disease. The field of public health-related …

Metal-Organic Frameworks As Potential Platforms For Carbon Dioxide Capture And Chemical Transformation, Wenyang Gao

USF Tampa Graduate Theses and Dissertations

The anthropogenic carbon dioxide (CO₂) emission into the atmosphere, mainly through the combustion of fossil fuels, has resulted in a balance disturbance of the carbon cycle. Overwhelming scientific evidence proves that the escalating level of atmospheric CO₂ is deemed as the main culprit for global warming and climate change. It is thus imperative to develop viable CO₂ capture and sequestration (CCS) technologies to reduce CO₂ emissions, which is also essential to avoid the potential devastating effects in future. The drawbacks of energy-cost, corrosion and inefficiency for amine-based wet-scrubbing systems which are currently used in industry, …

Effect Of Void Fraction On Transverse Shear Modulus Of Advanced Unidirectional Composites, Jui-He Tai

USF Tampa Graduate Theses and Dissertations

In composite materials, transverse shear modulus is a critical moduli parameter for designing complex composite structures. For dependable mathematical modeling of mechanical behavior of composite materials, an accurate estimate of the moduli parameters is critically important as opposed to estimates of strength parameters where underestimation may lead to a non-optimal design but still would give one a safe one.

Although there are mechanical and empirical models available to find transverse shear modulus, they are based on many assumptions. In this work, the model is based on a three-dimensional elastic finite element analysis with multiple cells. To find the shear modulus, …

Enforcing Security Policies On Gpu Computing Through The Use Of Aspect-Oriented Programming Techniques, Bader Albassam

USF Tampa Graduate Theses and Dissertations

This thesis presents a new security policy enforcer designed for securing parallel computation on CUDA GPUs. We show how the very features that make a GPGPU desirable have already been utilized in existing exploits, fortifying the need for security protections on a GPGPU. An aspect weaver was designed for CUDA with the goal of utilizing aspect-oriented programming for security policy enforcement. Empirical testing verified the ability of our aspect weaver to enforce various policies. Furthermore, a performance analysis was performed to demonstrate that using this policy enforcer provides no significant performance impact over manual insertion of policy code. Finally, future …

Electrospinning Of Polymeric Solutions Using Opuntia Ficus-Indica Mucilage And Iron Oxide For Nanofiber Membranes For Treating Arsenic Contaminated Water, Venkatesh Eppili

USF Tampa Graduate Theses and Dissertations

Water is the essential part of every organism and it is also a vital constituent of healthy living and diet. Unfortunately water contamination over the past decade has increased dramatically leading to various diseases. As technology advances, we are detecting many pollutants at smaller levels of concentrations. Arsenic (As) is one of those major pollutants, and Arsenic poisoning is a condition caused due to excess levels of arsenic in the body. The main basis for Arsenic poisoning is from ground water which naturally contains high concentrations of arsenic. A case study from 2007 states that over 137 million people in …

Oversampling Methods For Imbalanced Dataset Classification And Their Application To Gynecological Disorder Diagnosis, Iman Nekooeimehr

USF Tampa Graduate Theses and Dissertations

In many applications, the dataset for classification may be highly imbalanced where most of the instances in the training set may belong to some of the classes (majority classes), while only a few instances are from the other classes (minority classes). Conventional classifiers will strongly favor the majority class and ignore the minority instances. The imbalance problem can occur in both binary data classification and also in ordinal regression. Ordinal regression is a supervised approach for learning the ordinal relationship between classes. Extensive research has been performed for addressing imbalanced datasets for binary classification; however, current methods do not address …

Impact Of Sludge Layer Geometry On The Hydraulic Performance Of A Waste Stabilization Pond, Faissal Romaric Ouedraogo

USF Tampa Graduate Theses and Dissertations

Improving the hydraulic performance of waste stabilization ponds (WSPs) is an important management strategy to not only ensure protection of public health and the environment, but also to maximize the potential reuse of valuable resources found in the treated effluent. To reuse effluent from WSPs, a better understanding of the factors that impact the hydraulic performance of the system is needed. One major factor determining the hydraulic performance of a WSP is sludge accumulation, which alters the volume of the pond.

In this study, computational fluid dynamics (CFD) analysis was applied to investigate the impact of sludge layer geometry on …

Preparation And Characterization Of Van Der Waals Heterostructures, Horacio Coy Diaz

USF Tampa Graduate Theses and Dissertations

In this dissertation different van der Waals heterostructures such as graphene-MoS₂ and MoTe₂-MoS₂ were prepared and characterized. In the first heterostructure, polycrystalline graphene was synthesized by chemical vapor deposition and transferred on top of MoS₂ single crystal. In the second heterostructure, MoTe₂ monolayers were deposited on MoS₂ by molecular beam epitaxy.

Characterization of graphene-MoS₂ heterostructures was conducted by spin and angle resolve spectroscopy which showed that the electronic structure of the bulk MoS₂ and graphene in this van der Waals heterostructures is modified. For MoS₂ underneath the graphene, a band …

Sustainability At U.S. Urban Water Utilities: A Framework To Assess Key Attributes, Matthew Paul Ries

USF Tampa Graduate Theses and Dissertations

Urban water utilities in the United States face challenges due to a combination of external drivers. These include urbanization and population growth, which are stressing a system of aging infrastructure. Compliance with increasing regulations is also a challenge in a fiscally-constrained economic environment. A changing climate threatens infrastructure and past assumptions for water supply and quality. Urban utilities provide clean water and sanitation services to over 80% of the country’s population and its industrial centers. Therefore, the sustainability of these water utilities are crucial to the country’s and the public’s well-being.

New operating models are emerging for a “utility of …

The Design And Testing Of A Novel Batch Photocatalytic Reactor And Photocatalyst, Shawn Sasser

USF Tampa Graduate Theses and Dissertations

With an ever-increasing human population, the importance in having sustainable energy resources is becoming increasingly evident, as the current energy habits have brought about massive atmospheric pollution in the form of CO₂ emissions, resulting in a rise in the average global temperature. To battle the effects of climate change, many alternative energy resources have been investigated. Among these, photocatalytic conversion of CO₂ to renewable hydrocarbon fuels such as methane and methanol is one of the most desirable, as it provides the opportunity to utilize the sun’s energy to convert CO₂ to renewable fuels. The work in this …

Nano-Photonic Waveguides For Chemical And Biomedical Sensing, Surya Venkatasekhar Cheemalapati

USF Tampa Graduate Theses and Dissertations

In this dissertation, advances in the fields of Photonics, and Plasmonics, and specifically, single cell analysis and waveguide sensing will be addressed. The first part of the dissertation is on Finite Difference Time Domain (FDTD) optimization and experimental demonstration of a nano-scale instrument that allows sensing at the cellular and subcellular levels. A new design of plasmonic coupler into a nanoscale waveguide is proposed and optimized using FDTD simulations. Following this, a subcellular nanoendoscope that can locally excite fluorescence in labelled cell organelles and collect the emitted fluorescent light for detailed spectrum analysis is fabricated and tested. The nanoendoscope has …

Renewable Energy Investment Planning And Policy Design, Alireza Ghalebani

USF Tampa Graduate Theses and Dissertations

In this dissertation, we leverage predictive and prescriptive analytics to develop decision support systems to promote the use of renewable energy in society. Since electricity from renewable energy sources is still relatively expensive, there are variety of financial incentive programs available in different regions. Our research focuses on financial incentive programs and tackles two main problem: 1) how to optimally design and control hybrid renewable energy systems for residential and commercial buildings given the capacity based and performance based incentives, and 2) how to develop a model-based system for policy makers for designing optimal financial incentive programs to promote investment …

Design Exploration And Application Of Reversible Circuits In Emerging Technologies, Saurabh Kotiyal

USF Tampa Graduate Theses and Dissertations

The reversible logic has promising applications in emerging computing paradigms, such as quantum computing, quantum dot cellular automata, optical computing, etc. In reversible logic gates, there is a unique one-to-one mapping between the inputs and outputs. To generate a useful gate function, the reversible gates require some constant ancillary inputs called ancilla inputs. Also to maintain the reversibility of the circuits some additional unused outputs are required that are referred to as the garbage outputs. The number of ancilla inputs, the number of garbage outputs and quantum cost plays an important role in the evaluation of reversible circuits. Thus minimizing …

Increasing 18f-Fdg Pet/Ct Capabilities In Radiotherapy For Lung And Esophageal Cancer Via Image Feature Analysis, Jasmine Alexandria Oliver

USF Tampa Graduate Theses and Dissertations

Positron Emission Tomography (PET) is an imaging modality that has become increasingly beneficial in Radiotherapy by improving treatment planning (1). PET reveals tumor volumes that are not well visualized on computed tomography CT or MRI, recognizes metastatic disease, and assesses radiotherapy treatment (1). It also reveals areas of the tumor that are more radiosensitive allowing for dose painting - a non-homogenous dose treatment across the tumor (1). However, PET is not without limitations. The quantitative unit of PET images, the Standardized Uptake Value (SUV), is affected by many factors such as reconstruction algorithm, patient weight, and tracer uptake time (2). …

Adoption Of The Sawyer Water Filter In Peru, Stephanie D. Paredes

USF Tampa Graduate Theses and Dissertations

In Peru, lack of water, sanitation, and hygiene (WASH) results in 6,600 deaths per year that represents approximately 3.9% of total deaths. Three thousand and nine hundred of these deaths were due to diarrheal diseases (Prüss-Üstün et al., 2008). Systematic reviews suggest that interventions to improve microbial quality of drinking water are successful in reducing diarrheal diseases (Fewtrell et al., 2005; Clasen et al., 2007; Fry et al., 2013). Interventions for household water treatment and safe storage to ensure safe drinking water reduce diarrhea by 31-52% (WHO/UNICEF, 2013).

The SAWYER PointONE filter, a portable and adaptable membrane filtration device as …

Conversion Of Landfill Gas To Liquid Hydrocarbon Fuels: Design And Feasibility Study, Ryan Alexander Kent

USF Tampa Graduate Theses and Dissertations

This paper will discuss the conversion of gas produced from biomass into liquid fuel through the combination of naturally occurring processes, which occur in landfills and anaerobic digesters, and a gas-to-liquids (GTL) facility. Landfills and anaerobic digesters produce gases (LFG) that can be converted into syngas via a Tri-reforming process and then synthesized into man-made hydrocarbon mixtures using Fischer-Tropsch synthesis. Further processing allows for the separation into liquid hydrocarbon fuels such as diesel and gasoline, as well as other middle distillate fuels. Conversion of landfill gas into liquid fuels increases their energy density, ease of storage, and open market potential …

Water Metering In Rural, Piped, Community-Managed Water Systems In The Developing World, Simona Platukyte

USF Tampa Graduate Theses and Dissertations

In the early 1990s, the United Nations (UN) recognized water as a finite resource to the entire ecosystem with an economic value that should be developed and managed based on the participatory approach using the Integrated Water Resource Management (IWRM) strategy. Many studies on water management practices have thus emerged in the developing world. Of particular interest to this work is the management of water through metering, price-setting, and rule enforcement in the rural setting in piped, community-owned water systems. There is very little published information regarding metering, enforcement experiments, and experiences in these systems. This is because metering and …

Modified Yttrium Hydroxide/Mc Nylon Nanocomposites And Scaling Effects In Multilayer Polyethylene Films, Jia Chen

USF Tampa Graduate Theses and Dissertations

In this thesis, monomer casting (MC) nylon was synthesized. MC nylon could replace nonferrous metals in certain applications, including gears, wheels, and other moving parts. However, compared with metals, MC nylon products have poor strength and stiffness, and crack easily, especially at low temperatures. In addition, the dimensional stability of MC nylon is poor, especially in the large casting nylon products, causing significant internal stresses due to shrinkage. Thus, MC nylon cracks easily when cast and molded. The yttrium hydroxide particles were modified by stearic acid and dispersed in the caprolactam. The polymerization time was short due to fast anionic …

Modeling The Extent Of Virus Removal In Waste Stabilization Ponds To Support Reuse Of Wastewater, Kelly James Vannoy

USF Tampa Graduate Theses and Dissertations

Waste stabilization ponds (WSPs) are one of the most prevalent types of domestic wastewater treatment technologies employed worldwide, and global stressors such as urbanization, population growth, climate change, and water scarcity have increased the demand for reusing treated wastewater. The safe reuse of treated wastewater in agriculture can ease water scarcity, aid in food production, and reduce environmental degradation from the discharge of wastewater effluent to surface waters. The ability to predict virus concentrations in wastewater effluent is an important criterion for determining whether wastewater is suitable for discharge to the environment or for reuse in agriculture. However, many uncertainties …

Enhancement Of Supercapacitor Energy Storage By Leakage Reduction And Electrode Modification, Tete Tevi

USF Tampa Graduate Theses and Dissertations

Supercapacitors have emerged in recent years as a promising energy storage technology. The main mechanism of energy storage is based on electrostatic separation of charges in a region at the electrode-electrolyte interface called double layer. Various electrode materials including carbon and conducting polymers have been used in supercapacitors. Also, supercapacitors offer high life cycle and high power density among electrochemical energy storage devices. Despite their interesting features, supercapacitors present some disadvantages that limit their competitivity with other storage devices in some applications. One of those drawbacks is high self-discharge or leakage. The leakage occurs when electrons cross the double layer …