Physical Sciences and Mathematics Commons^™

Design And Implementation Of A Multi-Port Solid State Transformer For Flexible Der Integration, Mohammad Rashidi

Theses and Dissertations

Conventional power system includes four major sections, bulk generation, transmission network, distribution network, and loads. The main converter in the conventional electric grid is the low-frequency passive transformer providing galvanic isolation and voltage regulation for various voltage zones. In this configuration, small-scale renewable energy resources are generally connected to the power system at low voltage zones or inside microgrids.

Recent developments in the design of power electronic elements with higher voltage and power ratings and medium/high frequency enable making use of solid state transformer at different voltage levels in the distribution system and microgrid design. In this work, the concept …

Real-Time, Selective Detection Of Heavy Metal Ions In Water Using 2d Nanomaterials-Based Field-Effect Transistors, Guihua Zhou

Theses and Dissertations

Excessive intake of heavy metals damages the central nervous system and causes brain and blood disorders in mammals. Heavy metal contamination is commonly associated with exposure to mercury, lead, arsenic, and cadmium (arsenic is a metalloid, but classified as a heavy metal). Traditional methods to detect heavy metal ions include graphite furnace atomic absorption spectroscopy (GFAAS), inductively-coupled plasma optical emission spectroscopy (ICP-OES), and inductively-coupled plasma mass spectroscopy (ICP-MS). Recently, many new methods have been proposed to detect heavy metal ions, including atomic absorption spectrometry, fluorescent sensors, colorimetric sensors, electrochemical sensors, X-ray absorption fine structure spectroscopy, ultrasensitive dynamic light scatting assays, …

Phylogeography Of An Estuarian Calanoid Copepod; Acartia Tonsa In The Texas Gulf Of Mexico, Nicole J. Figueroa

Theses and Dissertations

The calanoid copepod, Acartia tonsa is one of the most abundant and well-studied estuarian species. However, the idea that this cosmopolitan species has unrestricted dispersal and high gene flow has been challenged. In this study, a more holistic picture of the phylogeography of A. tonsa was developed using the mitochondrial gene cytochrome oxidase one (mtCOI). Multiple new lineages were found in the Texas Gulf of Mexico that are basal to Northeastern Atlantic lineages. Connectivity was also observed between Brazil and the Texas Gulf of Mexico. The revised phylogeny shows a clear pattern of cryptic speciation as the species made a …

Evaluating Ensemble Wind Downscaling Methodologies Over A Coastal Estuary, Bryan Paul Holman

Theses and Dissertations

Current numerical weather prediction (NWP) ensemble systems are biased and under dispersive. While statistical methods have been developed to correct for these errors, the resulting post processed forecasts are typically available at observing stations only. Yet post processed forecasts are needed everywhere. Additionally, the horizontal grid spacing of current ensemble systems is too coarse to resolve the Indian River Lagoon (IRL), a coastal estuary in central Florida that impacts the local wind climatology. Thus, computationally reasonable approaches are needed that simultaneously downscale and post process ensemble wind forecasts. Currently no approach exists to do this, particularly in coastal areas such …

Numerical Study Of Thermal Performance Improvement By Novel Structures In The Building Energy Storage Systems, Junling Xie

Theses and Dissertations

In this work, numerical studies were conducted to investigate the effectiveness of two fin-like novel structures used for heat-transfer enhancement in two building energy storage systems including thermal energy storage and battery energy storage.

Firstly, thin layer ring structure was numerically investigated for thermal performance improvement in the thermal energy storage. From the results obtained in this study, the area ratio can be increased by 4% when using the thin layer ring during the same time period. The thin layer ring structure can shorten ice formation period and increase its efficiency. Further study was conducted for the factorial analysis of …

Development Of Lower Rio Grande River Water Quality Transportation Numerical Model For Bi-National River Management, Jose O. Gonzalez

Theses and Dissertations

Traditionally, water quality modelling has focused on modelling individual water bodies. However, water quality management problems must be analyzed at the larger scale to include influences from various water bodies that are interconnected. This paper provides a study on the hydrologic and quality transportation calculation by developing a hydrodynamic (unsteady state) channel routing model using a water-balanced approach. A one dimension Lagrangian river model was developed and applied to the 210 plus miles for the lower Rio Grande River Basin from the Falcon Dam to the head water of Brownsville that pours onto the Gulf of Mexico. This model can …

Removal Of Lead And Arsenic From Aqueous Solution By Biochar Produced From Locally-Sourced Biomass, Sergio I. Mireles

Theses and Dissertations

This study evaluated the effectiveness of four adsorbent materials, pyrolyzed corn stover, orange peel, pistachio shell, and magnetic biochar for their ability to adsorb lead (Pb) and arsenic (As III, As V) from aqueous solution. An increase in adsorption was seen as the pH of the solution increased from pH 2 to pH 6. Magnetic orange peel biochar with Fe3O4 particles precipitated on the surface of biochar was synthetized by co-precipitation and used for arsenic adsorption. Initial pH value had an influence on the adsorption behavior of As (III) and As (V). In the pH range of 2–6, As (V) …

Thermal Consolidation Of Dredge Sand For Artificial Reef Formations, Alexandro Trevino

Theses and Dissertations

Coral Reef ecosystems have degraded over years due to a variety of environmental issues such as ocean acidification. The continuous stress has detrimental effects on coral reef ecosystems that can possibly lead to the loss of the ecosystem. Our research aims to construct a prototype of an artificial reef by consolidating dredge sand from the ship channels of South Texas. Consolidation is achieved through an aluminum polytetrafluoroethylene self-propagating high temperature process that yields a solid formation to mimic the physical properties of coral reef structures. Using thermodynamic calculations, the variation of initial components was determined that reached an adiabatic temperature …

Is It Rational To Care About The Natural Environment?, Joshua Brown

Theses and Dissertations

This paper helps address the question of how people who currently care about the natural environment, or nature, might rationally persuade those who do not currently have such concern. Philosophers have largely ignored this question, but it is important outside philosophy. For instance, many environmental advocates seem to believe that others should care about nature. At least much writing that falls under the broad category of environmentalism intends to persuade us to care about nature in one way or another.

In this paper, I argue that people should care about nature to the extent that they have three other, rationally …

Utilizing Natural And Man-Made Resources For Economic Development: What Are The Mechanisms And Why?, Linh Pham

Theses and Dissertations

This dissertation studies the roles of natural resources in determining economic outcomes such as innovation, investment, profitability and economic growth.

The first chapter studies the ease of substitution between energy and other production inputs over time and across countries. Improvements in energy efficiency over the past decades have substantially decreased the amount of energy used per unit of capital. Yet, previous literature often assumes a constant elasticity of substitution between capital and energy. In this chapter, we develop a Solow growth model with a variable elasticity of substitution (VES) between production inputs and show that the long-run growth rate directly …

Operationalizing Resilience In The Face Of Water Conflict: Linking Social And Ecological Systems, Stephen Andrew Mcguire

Theses and Dissertations

This dissertation investigates the possibility of linked surface-groundwater governance through the application of a social-ecological systems lens to the Lake Beulah Conflict over a high capacity well in Walworth County, Wisconsin. Potential adverse impacts the loss of Ca2+ rich groundwater would have on Lake Beulah’s water quality was modeled through an ex-ante assessment method using the U.S. Army Corps of Engineers lake and reservoir model BATHTUB, the U.S. Geological Survey geochemical model PHREEQC and a Ca2+ mass balance equation. The utility of this information in a management setting was also analyzed. Reduction of Ca2+ through groundwater withdrawal revealed a eutrophication …

Reducing The Environmental Impacts Of Building Materials: Embodied Energy Analysis Of A High-Performance Building, Layla Qarout

Theses and Dissertations

The purpose of this research was to assess the embodied energy and carbon emissions of structural building materials, and determine environmental savings associated with construction. In common architectural practice, the analysis of the environmental cost of materials is typically not taken into account. This can be attributed to the lack of available data, loyalty to conventional construction methods, and complexity of embodied energy calculations. Although efforts are made to ensure accuracy of the information contained in energy databases, they are based on public domain sources and the “best” energy and carbon coefficients, with no guarantee to accuracy. Therefore, it is …

Decomposition Of Black Mangrove (Avicennia Germinans ) Leaf Litter: Calibrating Estuarine Indicators Of Functional Recovery, Leticia Martinez Contreras

Theses and Dissertations

Decomposition of plant material produced by mangroves and other macrophytes in estuaries occurs in both sediments and the water column. Early and intense processing could be more common in the water. In a previous study, in situ decomposition rates of Black Mangrove (Avicennia germinans ) leaf litter suspended in the water column differed among three estuaries in south Texas with moderate differences in salinity, water temperature, available nitrogen (N), and tidal flow. A series of microcosm experiments were conducted to determine the influence, within observed ranges in the estuaries, of these water variables on mass loss of Black Mangrove …

Increasing Marine Debris Awareness Through Public Education And Analyzing Fish For Microplastic And Pollutant Contamination, Stephanie R. Dubois

Theses and Dissertations

Marine debris is any persistent solid material that is manmade and then disposed of into the world’s oceans. Outreach and education was used in combination with biological research using an indicator fish species to raise awareness about the impacts of marine debris and encourage change in behavior to reduce marine debris. Pre and post surveys were administered during marine debris education tours for K-12 students at the Coastal Studies Lab on South Padre Island, Texas to determine change in knowledge and behavior regarding marine debris. Pinfish were collected from Laguna Madre and stomachs and livers removed for microplastics content and …

Investigating The Application Of Multibeam Sonar And Remotely Operated Vehicles In Fish Population Monitoring On Artificial Reefs, Robert Figueroa-Downing

Theses and Dissertations

Implementation of ROVs and multibeam imaging sonar in fisheries research has the potential to improve the accuracy and efficiency of current monitoring practices. This study aimed to 1) compare ROV video and diver abundance estimates; 2) evaluate fish length measurement accuracy from sonar; 3) investigate key differentiating sonar characteristics. Results indicate: 1) Diver surveys captured greater diversity of species; survey methods were comparable with regards to conspicuous species (r = 0.089, p = 0.074); 2) Length measurements from multibeam imaging sonar had high predictive power (Rho = 0.998; p < 0.001) of actual standard lengths and; 3) variations between samples were largely due to swim bladder echo, relative position of the target fish, and schooling characteristics. We conclude that 1) ROVs are less apt at observing cryptic species; 2) The Blueview P900-90 sonar can accurately measure fish length; and 3) swim bladder morphology plays an important role in fish identification.

Creating A Scaling Relationship Between Peak Discharge And Drainage Area To Identify Tile Drainage Inputs Into An Agricultural Stream, Ryan Plath

Theses and Dissertations

Tile drains have been shown to contribute to high levels of nitrate in agricultural streams. Locations of tile drains on a watershed scale, however, are often unknown due to tile drains being located on many separate parcels of private property. This study evaluates the ability of a methodology, using scaling relationships between discharge and drainage area, for locating areas of large tile drainage contribution to Money Creek, in McLean County, Illinois. Additionally, this study examines the difference in scaling relationships and physical stream hydrology between tileflow and no-tileflow conditions. Eight stream sites were created in the watershed, that recorded stage …

Environmental Applications Of Small Unmanned Aircraft Systems In Multi-Service Tactics, Techniques, And Procedures For Chemical, Biological, Radiological, And Nuclear Reconnaissance And Surveillance, Brandon B. Barnes

Theses and Dissertations

Small unmanned aircraft systems can be used for a variety of environmental applications. SUAS under 50 kg have the most utility at the tactical level and benefit from the research and development of systems currently being manufactured. Integrating chemical sensors into these systems can enhance Multi-service Tactics, Techniques, and Procedures for Chemical, Biological, Radiological, and Nuclear Reconnaissance and Surveillance. Considering the advantages and disadvantages in the fundamental science of twelve detection technologies, four types of sensors emerged as candidates for SUAS integration. Using specifications from commercial-off-the-shelf sensors, these four detection technologies (Electrochemical, Metal Oxide Semiconductor, Photoionization, and Catalytic Bead) were …

Adsorption Of Perfluorinated Compounds From Post-Emergency Response Wastewater, Christopher T. Schmidt

Theses and Dissertations

This research investigated the efficacy of granular activated carbon (GAC) as a method to treat water impacted with aqueous film forming foam (AFFF) after a firefighting response. Bench-top experiments were conducted and compared to field scale adsorber performance removing mg/L concentrations of PFAS in water contaminated with Military Specification AFFF. Batch tests compared four adsorbents, and determined Calgon F600 GAC and Rembind Plus mixed carbon media had the greatest perfluorooctane sulfonate (PFOS) capacities. Additional batch isotherm experiments using AFFF and higher PFOS concentrations (mg/L) indicated larger amounts of GAC are required (>30mg/L) for effective removal. Full-scale testing simulated an …

The Impacts Of Climate Change And Anthropogenic Processes On Permafrost Soils And Usaf Infrastructure Within Northern Tier Bases, Alexander J. Graboski

Theses and Dissertations

The Department of Defense is planning over $552M in military construction on Eielson Air Force Base within the next three fiscal years. Although many studies have been conducted on permafrost and climate change, the future of our climate as well as any impacts on permafrost soils, remains unclear. This research focused on future climate predictions to determine likely scenarios for the United States Air Force’s Strategic Planners to consider. The most recent 2013 International Panel on Climate Change report predicts a 2.2ºC to 7.8ºC temperature rise in Arctic regions by the end of the 21st Century in the Representative Concentration …

Dynamics Of Nitrate, Phosphorus, And Suspended Sediment Transport In Two Agricultural Streams In Central Illinois, Luke W. Lampo

Theses and Dissertations

Nutrients such as nitrate and phosphorus are necessary for life, but excessive amounts can be detrimental. Large amounts of nutrients entering bodies of water can lead to hypoxic zones such as the one in the Gulf of Mexico. Nutrients are also problematic in drinking water reservoirs, as high concentrations of nitrate in drinking water can cause health conditions such as blue baby syndrome and high phosphorus concentrations can lead to algal blooms. Suspended sediment leads to reservoir sedimentation, habitat degradation, and is able to transport particulate nutrients. High nutrient and sediment concentrations are a recurring problem in the drinking water …

Death And Destruction: Insight Into The Rhino Poaching Epidemic In South Africa, Richard Wayne Charlton

Theses and Dissertations

The poaching of wildlife has been a concern to many involved in the protection of wildlife. Poaching is found throughout the world and has been around for thousands of years. In the past century, poaching has reached new heights and the concern of an extinction of a species has bought the topic of poaching to new light. Whilst poaching has been seen as a biological or conservation topic in the past, criminologists around the world have now started to delve into the topic. The poaching of wildlife and more so in recent years, rhino poaching, has been a concern in …

Short-Term Effects Of Nutrients On A Barrier Island Grassland Community, Ashley Moulton

Theses and Dissertations

Increased nutrient availability globally has the potential to affect community functional composition of plants in nutrient limited environments, such as coastal grassland systems. Stability of these systems are threatened worldwide by urbanization, as well as effects of sea level rise and increased frequency and intensity of storms, and atmospheric N deposition, associated with climate change. Annual net primary productivity (ANPP), species composition, and functional traits (community weighted specific leaf area (CWSLA), leaf area index (LAI), growth form and photosynthetic pathway) were measured across four treatments to assess multiple resource limitation of nitrogen (N) and phosphorus (P) and functional community response …

A Study Of Two Digital Hydrological Networks In South Carolina And An Assessment Of Site Reconnaissance Results From The Sc Department Of Health And Environmental Control Probability Survey For Streams And Rivers, Caitlin Smith

Theses and Dissertations

The South Carolina Department of Health and Environmental Control (SCDHEC), Surface Water Monitoring Section utilizes a probability survey to assess water quality conditions of streams and rivers in the state. The Generalized Random-Tessellation Stratified survey design prioritizes specific stream order (size) subpopulations and spatial distribution in the generation of potential sample sites, and is intended to survey only perennial stream reaches. Site reconnaissance is conducted to assess site suitability and accessibility. The stream characteristics associated with accepted and rejected sites have been recorded since the late 1990s/early 2000s. Data from 2001-2016 was analyzed to assess apparent trends in both rejected …

A Study Of Sediment Accretion Dynamics In Mature And Restored Tidal Freshwater Forested Wetlands In The James River Watershed Using Surface Elevation Tables And Marker Horizons, Ronaldo Lopez

Theses and Dissertations

Sediment accretion and elevation change in tidal forests, and the corresponding ability of these wetlands to keep pace with sea-level rise (SLR), represent data gaps in our understanding of wetland sustainability. Surface Elevation Tables and marker horizons were installed in three mature tidal forests and a restored tidal marsh, allowing us to measure elevation change, accretion, and subsidence. Additionally, we measured predictor variables to test for their significance in explaining accretion and elevation change rates. Mean accretion at our sites was 11.67 +/- 3.01 mm yr^-1 and mean elevation change was -20.22 +/- 8.10 mm yr^-1, suggesting …

Population Dynamics Of A Recently Described And Rare Plant Species: Stachys Caroliniana (Lamiaceae), Shelby Moody

Theses and Dissertations

Stachys caroliniana J.B. Nelson & D.A. Rayner, a newly described ‘hedge-nettle’ is found in two locations in South Carolina. The first known collection of this species is from the Santee Coastal Reserve in Charleston County. The second location (the type locality) is from the Tom Yawkey Wildlife Center in Georgetown County, approximately 8 air miles northeast of the first location. This study focused on the population in Georgetown County. Population dynamics of Stachys caroliniana were studied in order to provide management guidelines to South Carolina Department of Natural Resources for this species. This was achieved by assessing suitable habitat conditions, …

Sanitary Sewer Overflows In Columbia, South Carolina And Their Impact On Mercury And Metal Cycling, Alison Emmons

Theses and Dissertations

Objectives. Microbial pathogens and their threat to human health have been the primary concern of sanitary sewer overflows (SSO); however, SSOs may also be a source of metals, including methylmercury, to local waterways. We hypothesized that SSOs had elevated concentrations of metals compared to nearby reference creeks.

Methods. Unfiltered and filtered (0.2 μm) surface water samples were collected monthly between November 2015 and March 2016 from three sewage-impacted creeks in Columbia, South Carolina. During this period, three sewage events were captured including an active SSO, a ruptured force main sewer pipe, and one site downstream from SSOs. In October 2016 …

A Comparison Of Pesticide Monitoring Programs, State Vs. Federal, Justin Marshall

Theses and Dissertations

Exposure to pesticide residues continues to be a threat to both human and environmental health despite increased efforts in the agricultural industry to control end-product levels. Multiple government agencies routinely sample and screen common agricultural commodities (fruits and vegetables) for pesticide residues, albeit to do so they use different commodity sampling methods and satisfy different program objectives. Often, results of such screening programs are used in a supplementary fashion in human and environmental health studies, but rarely are the results studied against one another. Six years of archived data (narrowed down from 14) of two separate pesticide monitoring programs were …

A Mechanistic Study Of Micro Rna 21 Induced Hepatic Fibrosis And Use Of Sparstolonin B In Remediation Of Environmental Nafld, Diptadip Dattaroy

Theses and Dissertations

Due to the increased prevalence of obesity, non-alcoholic fatty liver disease (NAFLD) has become a major public health problem in the Western world and Asian countries. Approximately a third of the general population in the US has NAFLD. NAFLD includes a spectrum of histological characteristics ranging from simple steatosis to steatohepatitis, fibrosis and cirrhosis and can be characterized into to two major phenotypes: nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). Water disinfection byproducts like trihalomethanes can act as crucial risk factors for NAFLD progression. Here I have studied the molecular mechanisms of a water disinfection byproduct, Bromodichloromethane, in induction …