Physical Sciences and Mathematics Commons^™

Microstructural Analysis Of Thermoelastic Response, Nonlinear Creep, And Pervasive Cracking In Heterogeneous Materials, Alden C. Cook

Electronic Theses and Dissertations

This dissertation is concerned with the development of robust numerical solution procedures for the generalized micromechanical analysis of linear and nonlinear constitutive behavior in heterogeneous materials. Although the methods developed are applicable in many engineering, geological, and materials science fields, three main areas are explored in this work. First, a numerical methodology is presented for the thermomechanical analysis of heterogeneous materials with a special focus on real polycrystalline microstructures obtained using electron backscatter diffraction techniques. Asymptotic expansion homogenization and finite element analysis are employed for micromechanical analysis of polycrystalline materials. Effective thermoelastic properties of polycrystalline materials are determined and compared …

Soil Moduli Obtained From A Back Pressure Constant Rate Of Strain Bender Element Consolidation Apparatus, Yi Zhao

Graduate Theses and Dissertations

A back-pressure saturated, constant-rate-of-strain consolidation device was modified to incorporate bender elements (BP-CRS-BE) and thus allowed for shear wave measurements during consolidation tests. This newly fabricated system has many advantages over other previous or current devices: 1) it can be utilized not only for laboratory prepared soil samples but also for field sampled soils such as Shelby tube samples, and 2) continuous compression curves, and continuous values of vertical hydraulic conductivity and coefficient of consolidation can be acquired with a significant reduction in testing time. Soil modulus values such as shear modulus and constrained modulus are also able to be …

Policy Design Tool For Managing Indoor Residential Water Demand In Water-Scarce Regions, Mujahed M. Thneibat

Open Access Dissertations

In view of population growth; climate change; and economic evolution, water resources in numerous parts of the world have reached their natural capacities. Consequently, the ability of many countries to grow; meet the basic needs of inhabitants; and protect the environment will be endangered like never before unless water resources are smartly handled and managed. ^ In the past few decades, many developed and developing countries have suffered from water scarcity, and more are certain to follow. The water security dilemma is much more challenging in developing countries. Water utilities have had to follow regulatory plans to manage demand on …

Geotechnical Properties Of The Travis Peak (Hosston) Formation In East Texas: A Compressive And Tensile Strength Analysis Using Regression Analysis., Pawan Kakarla

Electronic Theses and Dissertations

The estimation of rock mass strength is a key parameter in geotechnical engineering which is used in the design of geotechnical structures like tunnels, dams and slopes. Geotechnical engineering is the branch of civil engineering which works on the principles of soil and rock mechanics to evaluate subsurface conditions, stability of slopes, foundations of structures and construction of earthworks. The main focus of this study was to calculate the strength of Lower Cretaceous Travis Peak Formation rocks of East Texas and to check the accuracy by comparing it with Regression analysis. The parameters which were used were the Uniaxial Compression …

Field Emissions Of (Hydro)Chlorofluorocarbons And Methane From A California Landfill, Alexander H. Sohn

Master's Theses

A comprehensive field investigation was conducted at Potrero Hills Landfill (PHL) located in Suisun City, California to quantify emissions of twelve (hydro)chlorofluorocarbons (i.e. F-gases). The specific target constituents for this study included CFC-11, CFC-12, CFC-113, CFC-114, HCFC-21, HCFC-22, HCFC-141b, HCFC-142b, HCFC-151a, HFC-134a, HFC-152a, and HFC-245fa. The majority of the F-gas emission studies have been conducted outside of the United States and very limited field landfill emission data are available in the United States. Because of historical usage of blowing agents in insulation foams including CFC-11, HCFC-142b, HFC-134a, and HFC-245fa, models reported in literature predicted high F-gas emissions from a landfill …

Characterization And Delineation Of Karst Geohazards Along Rm652 Using Electrical Resistivity Tomography, Culberson County, Texas, Adam F. Majzoub

Electronic Theses and Dissertations

The Delaware Basin of West Texas and southeastern New Mexico is the major western subdivision of the Permian Basin and a northern extension of the Chihuahuan Desert. The major evaporite unit within the Delaware Basin is the Castile Formation, which consists of gypsum/anhydrite and is highly susceptible to dissolution and karsting. Manifestations of karst within the Castile outcrop are abundant and include sinkholes, subsidence features and caves, both epigene and hypogene in origin.

Land reconnaissance surveys conducted during the summer of 2015 documented abundant karst landforms in close proximity to a major thoroughfare, RM 652, in Culberson County, Texas. 2D …

Analyses Of Streamflow Change Patterns And Correlation Of These Changes With Sea-Surface Temperature Fluctuations, Kazi Ali Tamaddun

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis presents a comprehensive statistical analysis that determines the direction, rate, and interval of significant streamflow change patterns in the continental U.S. and correlates these changes with sea-surface temperature fluctuations. First, by using two non-parametric tests, namely, the Mann-Kendall trend test and the Pettitt’s test, the presence of long-term trends and abrupt shifts were determined at 10% significance level over continuously adjustable periods that stretched from 1903 to 2012. Modified versions of the tests were applied to account for the presence of persistence (autocorrelation) in data. Theil-Sen slope was determined to evaluate the rate of change across multiple temporal …

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 …

Simulation Of Value Stream Mapping And Discrete Optimization Of Energy Consumption In Modular Construction, Md Mukul Chowdhury

Theses and Dissertations

With the increased practice of modularization and prefabrication, the construction industry gained the benefits of quality management, improved completion time, reduced site disruption and vehicular traffic, and improved overall safety and security. Whereas industrialized construction methods, such as modular and manufactured buildings, have evolved over decades, core techniques used in prefabrication plants vary only slightly from those employed in traditional site-built construction. With a focus on energy and cost efficient modular construction, this research presents the development of a simulation, measurement and optimization system for energy consumption in the manufacturing process of modular construction. The system is based on Lean …

Channel Form And Processes In A Formerly Glaciated Terrain, Nathaniel Bergman

Electronic Thesis and Dissertation Repository

Despite that many places around the world in general, and North America in particular, were glaciated during the last ice age, relatively little is known about rivers that evolved over these landscapes once they deglaciated. These rivers are commonly categorized as alluvial with a glacial legacy, and often described as plain gravel-bed or sand-bed rivers. Alternatively, they are considered to be bedrock rivers when the glacial deposits were eroded and underlying rock was exposed. However, ignoring the glacial history of these rivers is scientifically wrong and they should be termed "semi-alluvial". This work shows that classification is important, not only …

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 …

Multiscale Wind Modelling For Sustainability And Resilience, Djordje Romanic

Electronic Thesis and Dissertation Repository

The research presented herein is a mix of meteorological and wind engineering disciplines. In many cases, there is a gap between these two fields and this thesis is an attempt to bridge that gap through multiscale wind modelling approaches. Data and methods used in this study cover a multitude of spatial and temporal scales. Applications are in the fields of sustainability and resilience. This relationship between multiscale wind modelling and sustainability and resilience is investigated examining several case studies of three different developments: urban, rural and coastal.

An urban wind modelling methodology is proposed and applied for a specific development …

Longitudinal Tidal Dispersion Coefficient Estimation And Total Suspended Solids Transport Characterization In The James River, Beatriz Eugenia Patino

Civil & Environmental Engineering Theses & Dissertations

The longitudinal dispersion coefficient is a parameter used to evaluate the effect of cross-sectional variations on substance mixing mechanisms in estuaries influenced by tide, wind and internal density variations. Considering a two dimensional approach, this study aims at evaluating a tidal area of the lower James River at approximately 19 miles upstream from the mouth at the Chesapeake Bay, in the City of Newport News, and applies an experimental procedure based on in-situ salinity concentrations to estimate the dispersion coefficient in the area where receives a discharge from the HRSD James River Wastewater Treatment Plant, and further characterizes Total Suspended …

Changing Trends In Wave Heights In The U.S. Mid-Atlantic Region, Hillary Lane

Civil & Environmental Engineering Theses & Dissertations

The pace and effects of climate change are an area of constant focus for coastal engineers as evolving patterns in the atmosphere worldwide affect the oceans and coasts on a regional and global scale. Surface waves respond to changing wind patterns both locally and from propagating swell, and the difficulty in predicting future wind patterns is well-established. Expectations that climate change will result in more frequent and intense coastal storms and consequently greater wave heights in the North Atlantic are still unrealized, and recent forecasts from a variety of atmosphere-ocean coupled global climate models instead predict decreasing wave heights through …

Effects Of Surrounding Water Table On A Forested Wetland Habitat In East Coast Of Virginia, Lane Stokes

Civil & Environmental Engineering Theses & Dissertations

Exchanges into and out of a wetland, including surface water flow, groundwater flow, and constituents in the flows, usually determine the wetland physicochemical characteristics and biodiversity. To date, of these three exchanges, groundwater flow is the least studied, particularly in the United States of America. In this thesis, field observations were conducted at a forested non-tidal wetland, located on a flat hilltop. The position of the wetland is such that groundwater outflow is the only significant exchange that could be impacted by the surrounding land use. In addition, a spatially variable steady-state model was set up to extrapolate the observations …

Guidance Index For Shallow Landslide Hazard Analysis, Cheila Cullen

Dissertations, Theses, and Capstone Projects

Rainfall-induced landslides are one of the most frequent hazards on slanted terrains. They lead to considerable economic losses and fatalities worldwide. Intense storms with high-intensity and long-duration rainfall have high potential to trigger rapidly moving soil masses due to changes in pore water pressure and seepage forces. Nevertheless, regardless of the intensity-duration of the rainfall, shallow landslides are influenced by antecedent soil moisture conditions. To the present day, no system exists that dynamically interrelates these two factors.

This work establishes a relationship between antecedent soil moisture and rainfall expressed in the form of a Shallow Landslide Index (SLI) at 1km …

Hydraulic And Electrokinetic Delivery Of Remediants For In-Situ Remediation, Ahmed I. A. Chowdhury

Electronic Thesis and Dissertation Repository

Nano-scale zero valent iron (nZVI) has shown promising mobility and in-situ reactivity with chlorinated volatile organic compounds when injected into saturated porous media. The current study evaluated nZVI mobility and subsequent reactivity with in-situ contaminants in a variably saturated porous media. The nZVI particles, synthesized onsite at subzero temperatures, demonstrated complete trichloroethene (TCE) degradation within the target area. Furthermore, a three dimensional finite difference model (CompSim) was utilized to investigate nZVI mobility in variably saturated zones. Model predicted well head data were in very good agreement with field observations. Simulation results showed that the injected slurry migrated radially outward from …

Calcium Carbonate Formation In Energy-Related Subsurface Environments And Engineered Systems, Qingyun Li

McKelvey School of Engineering Theses & Dissertations

Geologic CO2 sequestration (GCS) in subsurface saline aquifers is a promising strategy to mitigate climate change caused by increasing anthropogenic CO2 emissions from energy production. At GCS sites, interactions between fluids and geomedia are important because they can affect CO2 trapping efficiency and the safety of CO2 storage. These interactions include the dissolution and precipitation of minerals. One of the most important minerals is calcium carbonate, because it can permanently trap CO2.

In this work, Portland cement was used as a model geomedium to investigate the chemical reactions, mechanical alterations, transport of reactive fluids, and the interplay of all these …

Nanostructured Thin Film Synthesis By Aerosol Chemical Vapor Deposition For Energy Storage Applications, Tandeep Singh Chadha

McKelvey School of Engineering Theses & Dissertations

Renewable energy sources offer a viable solution to the growing energy demand while mitigating concerns for greenhouse gas emissions and climate change. This has led to a tremendous momentum towards solar and wind-based energy harvesting technologies driving efficiencies higher and costs lower. However, the intermittent nature of these energy sources necessitates energy storage technologies, which remain the Achilles heel in meeting the renewable energy goals. This dissertation focusses on two approaches for addressing the needs of energy storage: first, targeting direct solar to fuel conversion via photoelectrochemical water-splitting and second, improving the performance of current rechargeable batteries by developing new …

Lattice Boltzmann Methods For Wind Energy Analysis, Stephen Lloyd Wood

Doctoral Dissertations

An estimate of the United States wind potential conducted in 2011 found that the energy available at an altitude of 80 meters is approximately triple the wind energy available 50 meters above ground. In 2012, 43% of all new electricity generation installed in the U.S. (13.1 GW) came from wind power. The majority of this power, 79%, comes from large utility scale turbines that are being manufactured at unprecedented sizes. Existing wind plants operate with a capacity factor of only approximately 30%. Measurements have shown that the turbulent wake of a turbine persists for many rotor diameters, inducing increased vibration …

Asbestos Cement Pipe Condition Assessment And Remaining Service Life Prediction, Abiy Melles Ghirmay

Graduate Theses and Dissertations

This research details a condition assessment of asbestos cement (AC) pipe within in the Bella Vista Village Property Owners Association water distribution system. Bella Vista Village contains appropriately 300 miles of AC pipe with nominal diameters from 6-14 inch. The goal of the research is to determine the current condition of AC pipe within the system and predict future performance of the pipes. AC pipe samples were obtained from 23 locations disturbed across the distribution system with nominal pipe diameters of 6-8 inch. Estimates of current level of degradation were obtained using phenolphthalein staining and hardness measurements of each sample. …

Role Of River Bathymetry In Hydraulic Modeling Of River Channels, Sayan Dey

Open Access Theses

Accurate geometric representation of the river channel is required for accurate hydraulic modeling of rivers. These are generally obtained through remote sensing techniques such as Light Detection and Ranging (LIDAR). However, these techniques lack the ability to model the submerged channel bed effectively and need to be complemented with surveyed bathymetric data for complete representation of the channel bathymetry, which can be time and cost prohibitive. An alternative to address this issue is to develop conceptual models that can estimate bathymetry.

This study aims to evaluate the potential of a conceptual model, the River Channel Morphology Model (RCMM) which estimates …

Evaluating A Measure-Calculate Method For Determining Sediment Oxygen Demand In Lakes, Adrian Beirise

Graduate Theses and Dissertations

A steady-state mass diffusion model used with simple measurable and calculable inputs for determining sediment oxygen demand (SOD) is compared to an intact core incubation (ICI) SOD method using samples from three lakes. The mass diffusion model coupled with inputs is known as the measure-calculate method (M-C) and is a potential alternative to existing methods for measuring SOD which are more complex, time-consuming, and costly. The M-C method requires inputs for volumetric sediment oxygen uptake (Ṅsed), sediment density and porosity, and water properties. Ṅsed was determined by suspending sediment in oxygen-saturated water with a DO probe and determining the steady …

The Use Of Sodium Persulfate In Hydraulic Fracturing Fluids: A Degradation Study Based On Furfural, Katherine Elizabeth Manz

Masters Theses

Hydraulic fracturing has allowed natural gas to become a viable energy source via extraction of unconventional shale reserves, but this process requires an enormous amount of water. To ensure a productive fracture, a proprietary blend of chemical additives is added to the water. In this research, a hydraulic fracturing chemical additive – an enzyme breaking agent – is analyzed for organic components using gas chromatography mass spectrometry. The chemical changes that occur over the course of a fracture are also investigated using one model chemical found in the additive, furfural, in order to help assess the environmental risk that hydraulic …

Modelling Of Dreissenid Mussel Impacts On Lake Michigan, Chunqi Shen

Theses and Dissertations

Invasive dreissenid mussel appear to have profoundly altered Great Lakes food webs and nutrient cycles during the past several decades. Recent declines of phytoplankton were supposed to be highly related with the increase of mussel population. These phytoplankton declines were further found to be coincident with declines in the abundance of planktivorous fish. In addition, the resurgence of Cladophora in Great lakes was estimated to be associated with the high density colonization of mussels. More light is available at lake bottom due to the mussels’ graze effect. The mussels further promote Cladophora growth by fertilizing it with nutrient-rich excrement. And …

Trend Analysis Of Water Quality In Northwest Arkansas Streams Reflects Changes In The Watershed, Zachary Paul Simpson

Graduate Theses and Dissertations

Watershed export of nutrients, sediments, and chemicals impacts receiving waters. Changes within the watershed (e.g., anthropogenic or climatic) can alter the transport of constituents in streams. Stream monitoring is crucial for understanding these effects. This study developed a potential improvement to flow-adjusting constituent concentrations in streams, an important step of analyzing monitoring data in lotic systems for trends. The method incorporates a K-fold cross-validation procedure to optimize a model explaining the relationship between the concentration and streamflow, thus providing a valuable tool to researchers in water quality. Additionally, two case studies were conducted on watersheds located in northwest Arkansas using …

The Role Of Organic Matter In The Fate And Transport Of Antibiotic Resistance, Metals, And Nutrients In The Karst Of Northwest Arkansas, Victor Lee Roland Ii

Graduate Theses and Dissertations

Organic matter (OM) in the environment acts as a nutrient, but may also act as a transport vector for harmful chemical compounds and bacteria. Acetate is a labile form of OM produced during fermentation in anaerobic lagoons used to store animal fecal-waste from concentrated animal feeding operations (CAFOs). Dry and liquid fertilizers from CAFOs pose a threat to groundwater by introducing excessive amounts of nutrients (e.g. OM, nitrate and ammonia), metals, and antibiotic compounds. In the epikarst of Northern Arkansas in the Buffalo River watershed additional input of labile dissolved organic carbon (DOC) from liquid CAFO waste-fertilizers was hypothesized to …

Electrodeionization Versus Electrodialysis: A Clean-Up Of Produced Water In Hydraulic Fracturing, Brigitte Marie Rodgers

Graduate Theses and Dissertations

Electrodeionization (EDI) is a widely studied process ranging from applications in wastewater clean-up in the food and beverage industry to purifying organic compounds. To date, there are no apparent studies on applying this technology to produced wastewater recovered from hydraulic fracking sites. Water consumption within hydraulic fracturing sites can reach in the upwards of millions of gallons per site, so a need for a water recycling process becomes necessary within areas where water requirements are scarce. Implementation of an EDI module that is capable of handling high salt solutions from produced wastewater in subsequent fracturing practices will decrease overall water …

Robust Algorithms For Estimating Vehicle Movement From Motion Sensors Within Smartphones, Ilyas Ustun

Computational Modeling & Simulation Engineering Theses & Dissertations

Building sustainable traffic control solutions for urban streets (e.g., eco-friendly signal control) and highways requires effective and reliable sensing capabilities for monitoring traffic flow conditions so that both the temporal and spatial extents of congestion are observed. This would enable optimal control strategies to be implemented for maximizing efficiency and for minimizing the environmental impacts of traffic. Various types of traffic detection systems, such as inductive loops, radar, and cameras have been used for these purposes. However, these systems are limited, both in scope and in time. Using GPS as an alternative method is not always viable because of problems …

Possible Sources And Impacts Of Biochar Water Extractable Organic Compounds On Aquatic Microorganisms, Cameron Russell Smith

Chemistry & Biochemistry Theses & Dissertations

Smokeless biomass pyrolysis with application of biochar as a soil amendment could be a significant approach for carbon sequestration to possibly control climate change for energy and environmental sustainability. If biochar were to be utilized as a soil amendment and a carbon sequestration agent at Gt C scales, the release of potentially toxic compounds into soils and associated hydrological systems, through soil rainwater runoff and leaching, might have negative consequences, in both agro-ecosystems and aquatic environmental systems. Therefore, the main focus of this dissertation was to study the sources and chemical composition of biochar water extractable (soluble) organic compounds and …