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Robust Design Of Shield Tunnels ‒ Considering The Longitudinal Variation Of Input Parameters, Wenping Gong
Robust Design Of Shield Tunnels ‒ Considering The Longitudinal Variation Of Input Parameters, Wenping Gong
All Dissertations
This dissertation, aimed at developing an improved design methodology for shield tunnels that explicitly considers design robustness against longitudinal variation of input parameters (such as soil parameters). To this end, a new solution model for shield tunnel performance analysis was first developed. In this new model, the random field concept was employed to model the longitudinal variation of input parameters. The input parameters (in the longitudinal domain) that had been generated with Monte Carlo simulation (MCS) were used as inputs for the tunnel longitudinal behavior analysis. Here, the finite element method (FEM) based upon Winkler elastic foundation theory was employed. …
Modeling Sustainability In Renewable Energy Supply Chain Systems, Fei Xie
Modeling Sustainability In Renewable Energy Supply Chain Systems, Fei Xie
All Dissertations
This dissertation aims at modeling sustainability of renewable fuel supply chain systems against emerging challenges. In particular, the dissertation focuses on the biofuel supply chain system design, and manages to develop advanced modeling framework and corresponding solution methods in tackling challenges in sustaining biofuel supply chain systems. These challenges include: (1) to integrate 'environmental thinking' into the long-term biofuel supply chain planning; (2) to adopt multimodal transportation to mitigate seasonality in biofuel supply chain operations; (3) to provide strategies in hedging against uncertainty from conversion technology; and (4) to develop methodologies in long-term sequential planning of the biofuel supply chain …
Toward Understanding The Thermodynamics And Mechanisms Of Actinide Sorption Reactions, Shanna Estes
Toward Understanding The Thermodynamics And Mechanisms Of Actinide Sorption Reactions, Shanna Estes
All Dissertations
The environmental fate of actinides is greatly influenced by interfacial reactions, including sorption onto solid surfaces. Because changes in the primary hydration sphere of the actinide are expected to greatly influence the thermodynamics (i.e., reaction enthalpy and entropy) of these reactions, examining actinide sorption thermodynamics may provide insight into actinide sorption mechanisms. Additionally, examining actinide sorption thermodynamics may enhance the ability to model or predict these reactions in environmental or engineered systems where variable or elevated temperatures are expected. However, few researchers have studied actinide sorption thermodynamics. Therefore, this research examined the thermodynamics of Eu(III) (a trivalent actinide analog), Th(IV), …
Stochastic Wavenumber Estimation: Damage Detection Through Simulated Guide Lamb Waves, Garrison Stevens
Stochastic Wavenumber Estimation: Damage Detection Through Simulated Guide Lamb Waves, Garrison Stevens
All Theses
Structural Health Monitoring (SHM) is a field of research that seeks to identify the onset of damage in infrastructure systems such that catastrophic failures can be averted. Acoustic Wavenumber Spectroscopy (AWS) is an emerging SHM technique that can identify and locate change of thickness resulting from damage in thin plates through the estimation of the characteristic wavenumber. AWS measures the ultrasonically induced vibrations of thin plates by laser scanners and monitors the propagation of Rayleigh-Lamb waves through the structure. This method is particularly suitable for thin-walled structures such as those contained in pipes, airplanes, and wind turbine blades. While AWS …
Geotechnical Analysis Of The Foundation Of Fort Sumter National Monument Using Numerical Modeling, Daniel Kyser
Geotechnical Analysis Of The Foundation Of Fort Sumter National Monument Using Numerical Modeling, Daniel Kyser
All Theses
The foundational condition of the historical coastal fortification of Fort Sumter in Charleston, SC was analyzed though the use of numerical modeling. In this study, two-dimensional Finite Element (FE) analyses were conducted to assess the stability of the foundation-casemates-wall system in a coupled manner subjected to potential loadings such as ocean waves, storm surge and earthquake. The finite element model was verified by modeling the historical events (construction between 1820 and 1860, demolition due to artillery bombardment, reconstruction, earthquake, building of the Battery Huger, and the removal of fill from the parade ground) since the construction of the fort in …
Robust Geotechnical Design - Methodology And Applications, Lei Wang
Robust Geotechnical Design - Methodology And Applications, Lei Wang
All Dissertations
This dissertation is aimed at developing a novel robust geotechnical design methodology and demonstrating this methodology for the design of geotechnical systems. The goal of a robust design is to make the response of a system insensitive to, or robust against, the variation of uncertain geotechnical parameters (termed noise factors in the context of robust design) by carefully adjusting design parameters (those that can be controlled by the designer such as geometry of the design). Through an extensive investigation, a robust geotechnical design methodology that considers explicitly safety, robustness, and cost is developed. Various robustness measures are considered in this …
The Effects Of Secondary Trapping Mechanisms On Geologic Storage Of Carbon Dioxide, Catherine Ruprecht
The Effects Of Secondary Trapping Mechanisms On Geologic Storage Of Carbon Dioxide, Catherine Ruprecht
All Dissertations
The goal of this Dissertation is to further the understanding of secondary trapping mechanisms in geologic CO2 storage systems to improve storage design and security. This Dissertation takes the form of three chapters. The objective of the first chapter was to analyze the storage performance of supercritical and brine saturated CO2 injection strategies to determine their advantages and disadvantages on distribution and immobilization of CO2 and pressure buildup. Results showed dissolved CO2 injection was favorable in terms of storage security in all cases as it resulted in smaller areal extents on the caprock and did not …
Experimental Evidence For Colloid-Facilitated Transport Of Plutonium, Hilary Emerson
Experimental Evidence For Colloid-Facilitated Transport Of Plutonium, Hilary Emerson
All Dissertations
Colloid-facilitated transport of the actinides has been observed previously in the field on the kilometer scale. The objective of this work is to investigate the mechanisms of colloid-facilitated transport with controlled settings and conditions. The experimental work in this dissertation investigates transport of a ternary complex with iron oxide colloids, organic ligands and actinides in the presence of quartz or a natural sandy soil as well as simplified systems building up to the ternary complexes. The first three papers investigate the following: (1) unsaturated transport of iron oxide colloids in a natural sandy soil lysimeter with and without natural organic …
Combined Numberical And Experimental Assessment Of Steel Roof Decks Subjected To Windborne Debris, Robert Roper
Combined Numberical And Experimental Assessment Of Steel Roof Decks Subjected To Windborne Debris, Robert Roper
All Theses
In the summer of 2013, a steel roof deck manufacturer (Company A) approached Clemson University about testing their steel roof decking product to evaluate the performance of the steel roof deck to resist impact from tornado windborne debris using FEMA P-361 Design and Construction Guidance for Community Safe Rooms. To assist Company A in better serving their customers in areas prone to severe wind events and to facilitate use of their products in community safe rooms, debris impact tests were conducted on two cold-formed corrugated steel roof decking products. Community safe rooms are buildings that are constructed in accordance with …
Fast Fission Neutron Detection Using The Cherenkov Effect, Matthew Millard
Fast Fission Neutron Detection Using The Cherenkov Effect, Matthew Millard
All Theses
The Cherenkov effect in optically clear media of varying indices of refraction and composition was investigated for quantification of fast neutrons. The ultimate application of the proposed detection system is criticality monitoring. The optically clear medium, composed of select target nuclei, was coupled to a photomultiplier tube. Neutron reaction products of the target nuclei contained within the optical medium emit beta particles and gamma rays that produce Cherenkov photons within the medium which can be detected. Assessed media include quartz (SiO2), sapphire (Al2O3), spinel (MgAl2O4), and zinc sulfide (ZnS), which were irradiated with un-moderated 252Cf. Monte Carlo N-Particle (MCNP) code …
Optimizing Light Collection From Extractive Scintillating Resin In Flow-Cell Detectors, Amy Meldrum
Optimizing Light Collection From Extractive Scintillating Resin In Flow-Cell Detectors, Amy Meldrum
All Theses
The objectives of this study were to investigate the changes in light collection efficiency for flow cell detector as various parameters are altered to find the optimum flow cell configuration. Columns with inner diameters of 0.16 cm, 0.48 cm, 0.79 cm, and 1.11 cm were packed with synthesized nonporous, un-functionalized beads to measure their detection efficiencies for solutions containing 210Po, 14C, or 90Sr/90Y. The average diameter of the beads used in the experiments was 147 µm ± 33 µm. The highest detection efficiency for 210Po was 15.3 ± 3.9% with the 1.11 cm diameter column. The 1.11 cm diameter column …
Estimating Field At-Rest Lateral Stress Coefficient And Liquefaction Resistance Of Aged Sands, Md Hossian
Estimating Field At-Rest Lateral Stress Coefficient And Liquefaction Resistance Of Aged Sands, Md Hossian
All Dissertations
Published results of laboratory tests to evaluate the influence of the at-rest lateral stress coefficient (K0) and the overconsoildation ratio (OCR) on liquefaction resistance of sands are reviewed in this dissertation. It is found that significant increase in liquefaction resistance can occur with high K0 and/or high OCR. A unique relationship between liquefaction resistance of isotropic and anisotropic normally consolidated sands exists based on the published laboratory data. Relationships between liquefaction resistance of overconsolidated sands and normally consolidated sands also have been shown in previous laboratory studies. Based on the previous studies, expressions for K0 and OCR correction factors (KK0 …
Georgia's Water Policymaking Process And The Role Of Public Participation: Development And Analysis Of A Water Planning Process Evaluation Framework, Anna Eskridge
All Dissertations
This study analyzes the public's role in the regional water planning process that took place in the State of Georgia from 2009 to 2011. Specifically, this dissertation analyzes the extent to which a 'consensus-based' water planning process occurred by 1) examining the public participation plans that governed how the public was to contribute to the plan and policy formation, and 2) analyzing the public comments that were submitted at public meetings and commenting periods. By examining the participation plans and public comments, this study revealed the institutional, policy, legislative, and planning structures that influenced public participation in the regional water …
Using Gis To Prioritize Green Infrastructure Installation Strategies In An Urban Watershed, Lauren Owen
Using Gis To Prioritize Green Infrastructure Installation Strategies In An Urban Watershed, Lauren Owen
All Theses
This study seeks to quantify runoff volume generation and peak flow rates from the urban Sand River Headwaters to determine the most effective placement of additional green infrastructure in Aiken, SC. ArcMap 10.1, HEC-GeoHMS, and HEC-HMS were used to delineate a total outlet watershed along with subwatershed(s) for urban stormwater infrastructure system by 'burning' the stormwater system at an artificial elevation below the existing topologically-based Digital Elevation Model (DEM). The result was a higher resolution DEM that allowed for storm routing and subsequent volume and flow predictions compared to that based on the original DEM created by using Light Detecting …
Fluid Mud Gravity Currents Through Emergent Aquatic Vegetation, Nazli Yilmaz
Fluid Mud Gravity Currents Through Emergent Aquatic Vegetation, Nazli Yilmaz
All Dissertations
In this theoretical and experimental investigation, the propagation dynamics of the fluid-mud underflows form in pipeline dredge disposal operations in the designated areas are studied. These areas such as wetlands, nearshore waters are typically covered with stiff, cylindrical, emergent aquatic vegetation. The main goals of this study are to propose mathematical formulations for the bottom shear force and drag force of emergent stiff aquatic vegetation acting on the gravity current, and to present novel propagation modeling approaches. To be able to predict these forces, a friction coefficient (for the bottom shear force), and a drag coefficient (for vegetation skin friction …
Workability-Integrated Mixture Proportioning Method For Pervious Concrete, Betiglu Eshete Jimma
Workability-Integrated Mixture Proportioning Method For Pervious Concrete, Betiglu Eshete Jimma
All Dissertations
Portland cement pervious concrete (PCPC) is increasingly gaining attention as a preferred material in selected pavement applications. This concrete has several unique features, which makes it an environment-friendly construction material. Its porous structure allows precipitation to infiltrate directly into the ground. This reduces accumulation of a large amount of storm water in areas of heavy storms and recharges the ground water system, thus reducing the need for expensive storm water collection and treatment systems. Also, it allows the pollutants on pavement surfaces such as motor oil, etc. to drain into the subsurface be treated by native microbes in the soil, …
Building Envelope Failure Assessment Of Residential Developments Subjected To Hurricane Wind Hazards, James Grayson
Building Envelope Failure Assessment Of Residential Developments Subjected To Hurricane Wind Hazards, James Grayson
All Dissertations
An unfortunate global precedent has been set by hurricane wind hazard events that illustrate the importance of building resilient coastal communities. Although community resilience is heavily dependent upon the socioeconomic response of the community before, during, and after a hazard event, it is also dependent on the vulnerability of the community to a disaster. Therefore, one way that structural engineers can assist communities in becoming more resilient is to investigate and implement methods that mitigate the 'initial shock' experienced by a residential development subjected to a hazard event. The focus of this research was to develop a mechanics-based building envelope …
The Effects Of Amine Structure, Chloramine Species And Oxidation Strategies On The Formation Of N-Nitrosodimethylamine, Meric Selbes
The Effects Of Amine Structure, Chloramine Species And Oxidation Strategies On The Formation Of N-Nitrosodimethylamine, Meric Selbes
All Dissertations
To comply with the increasingly stringent disinfection by-product (DBP) regulations in the United States, many water treatment plants have been switching from chlorination to chloramination in the last decade. Although chloramination reduces the formation of regulated DBPs such as trihalomethanes and haloacetic acids, it causes the formation of nitrosamines. Nitrosamines are a class of compounds that are probable human carcinogens, mutagens and teratogens at concentrations as low as 0.2 ng/L. In particular, N-nitrosodimethylamine (NDMA) is the most frequently detected nitrosamine in distribution systems in the United States. Although, nitrosamines are currently not regulated by the USEPA, they have been recently …
Effects Of Natural Organic Matter On Contaminant Removal By Superfine Powdered Activated Carbon Coupled With Microfiltration Membranes, Mengfei Li
All Theses
Hybrid activated carbon/membrane systems are used in drinking water treatment for their significant capability of removing synthetic organic contaminants (SOCs) or taste-and-odor compounds along with particles. Preliminary data showed that decreasing the carbon particle size and creating superfine powdered activated carbon (S-PAC) removed phenanthrene and atrazine better than adsorbents with larger particle size in the presence of competitive adsorbents like natural organic matter (NOM). NOM is present in all natural water from degradation of terrestrial biomass which leaches from soil into a water source. Water treatment facilities target the removal of NOM because they are precursors to disinfection by-products formed …
Optimal Design Of Validation Experiments For Calibration And Validation Of Complex Numerical Models, Matthew Egeberg
Optimal Design Of Validation Experiments For Calibration And Validation Of Complex Numerical Models, Matthew Egeberg
All Theses
As prediction of the performance and behavior of complex engineering systems shifts from a primarily empirical-based approach to the use of complex physics-based numerical models, the role of experimentation is evolving to calibrate, validate, and quantify uncertainty of the numerical models. Oftentimes, these experiments are expensive, placing importance on selecting experimental settings to efficiently calibrate the numerical model with a limited number of experiments. The aim of this thesis is to reduce the experimental resources required to reach predictive maturity in complex numerical models by (i) aiding experimenters in determining the optimal settings for experiments, and (ii) aiding the model …
Potential Effects Of Geologic Storage Of Co2 On Surface Water And Shallow Groundwater, Shuangshuang Xie
Potential Effects Of Geologic Storage Of Co2 On Surface Water And Shallow Groundwater, Shuangshuang Xie
All Theses
ABSTRACT Storage of supercritical phase CO2 in deep saline aquifers is being considered to reduce greenhouse gases in the atmosphere, and this process is expected to increase the pressure in these deep aquifers. One potential consequence of pressurization is an increase in the upward flux of saline water. Saline groundwater occurs naturally at shallow depths in many sedimentary basins, so an upward flux of solutes could degrade the quality of aquifers, and threaten aquatic ecosystems where groundwater discharge is important. The objective of this research is to evaluate the impacts associated with increasing the upward flux of saline water as …
The Use Of Oxidants For Ndma Precursor Deactivation In Wastewater Treatment, Jaclyn Lauer
The Use Of Oxidants For Ndma Precursor Deactivation In Wastewater Treatment, Jaclyn Lauer
All Theses
Water treatment plants in the United States (US) have been switching from chlorination to chloramination in the search for a disinfection process to reduce formation of regulated disinfection by-products (DBPs). Unfortunately, the trade-off is the formation of N-nitrosamines. N-nitrosodimethylamine (NDMA) is the most commonly detected N-nitrosamine in US distribution systems. In the Integrated Risk Information Service (IRIS) database of the United States Environmental Protection Agency (USEPA), NDMA has been identified to have an estimated 10-6 lifetime cancer risk level at a concentration of 0.7 ng/L in drinking water. N-nitrosamines are currently not regulated by the USEPA; however, are listed on …
Decentralized Water Systems For Sustainable And Reliable Supply, Suraj Goverdhanam
Decentralized Water Systems For Sustainable And Reliable Supply, Suraj Goverdhanam
All Theses
The water industry is under enormous pressure to provide potable water in circumstances of increasing demands due to population growth, lifestyle change of people and depleting freshwater resources. Deteriorating infrastructure makes the task of meeting the human water consumption needs even more challenging. Distributed water supply systems are currently pursued as a sustainable alternative in arid regions of US to exploit the potential of water reclamation at community or district level to reduce the dependence on freshwater resources. An extension of such a distributed water supply alternative is a complete decentralized supply, which requires on-site water reclamation. The intention of …
Hollow Massive Timber Panels: A High-Performance, Long-Span Alternative To Cross Laminated Timber, William Graham Montgomery
Hollow Massive Timber Panels: A High-Performance, Long-Span Alternative To Cross Laminated Timber, William Graham Montgomery
All Theses
Since the development of Cross Laminated Timber (CLT), there has been a surge in interest in massive timber buildings. Furthermore, recent conceptual and feasibility designs of massive timber towers of 30 or more stories indicate that performance of mass timber structural elements can compete with other building materials in the commercial industry (MGB Architecture and Design et al.). However, in order for massive timber to penetrate the commercial market even further, a solution is needed for long-span massive timber floor systems. Unfortunately, CLT falls short in this area and is unable to span long distances. The hollow massive timber (HMT) …
Anaerobic And Aerobic Biodegradation Of The Oil Dispersant Components 1,2-Propanediol And 2-Butoxyethanol In Seawater, Benjamin Rhiner
Anaerobic And Aerobic Biodegradation Of The Oil Dispersant Components 1,2-Propanediol And 2-Butoxyethanol In Seawater, Benjamin Rhiner
All Theses
Oil spills are a recurring issue associated with fossil fuel consumption. The largest accidental oil spill in the history of the petroleum industry was the Deepwater Horizon explosion and seafloor well blowout, where the Deepwater Horizon oil rig exploded and sank, allowing the well to gush uncontrolled from April 20, 2010, until it was capped on July 15, 2010, releasing an estimated 210,000,000 gallons of oil. Oil dispersants were used in unprecedented quantities during the cleanup response to the spill with a total of 1,840,000 gallons of the dispersant COREXIT being applied. The goal of this research was to evaluate …
Predictive Model Development For Adsorption Of Organic Contaminants By Carbon Nanotubes, Onur Apul
Predictive Model Development For Adsorption Of Organic Contaminants By Carbon Nanotubes, Onur Apul
All Dissertations
The main objective of the study was to investigate mechanisms and statistical modeling of synthetic organic contaminant (SOC) adsorption by carbon nanotubes (CNTs). First, predictive models were developed for adsorption of low molecular weight aromatic compounds by multi-walled carbon nanotubes (MWCNTs) using experimental data for 59 compounds. Quantitative structure-activity relationship (QSAR) and linear solvation energy relationship (LSER) approaches were employed and developed models were externally validated using an independent dataset obtained from the literature. Up to date, no QSAR model has been reported for predicting adsorption of organics by CNTs. No LSER model is available which comprehensively investigates the adsorption …
Projections Of Future Us Design Wind Speeds Due To Climate Change For Estimating Hurricane Losses, Fangqian Liu
Projections Of Future Us Design Wind Speeds Due To Climate Change For Estimating Hurricane Losses, Fangqian Liu
All Dissertations
Hurricane is among the most dangerous and costliest natural hazards that affect the coastal environment of the United States (U.S.) every year. Hurricane activities have been observed to change in many aspects since the last century including the changes in both intensity and annual storm frequency. The extent to which aspect of climate change contributes to the variation in hurricane activities from long-term historical statistics is still not clearly understood at this point. This study examines the impacts of two climate change effects (change in annual storm frequency and sea surface temperature) on future U.S. design wind speeds for the …
An Examination Of Radionuclide Transport In The Vadose Zone Using Field Lysimeters, Michael Witmer
An Examination Of Radionuclide Transport In The Vadose Zone Using Field Lysimeters, Michael Witmer
All Theses
Understanding how radionuclides interact in the subsurface is important for the remediation of contaminated sites, assessment of risk due to radioactive waste disposal, and designing new radioactive waste management strategies. The current understanding of the geochemical behavior of radionuclides in the subsurface and more specifically the vadose zone has been developed through reactive transport modeling supplemented by laboratory experiments. Interactions between radionuclides with the mineral particles and organic matter in the vadose zone can be very complex and while laboratory experiments produce valuable data, few controlled, intermediate scale transport studies have been performed. In order to accurately predict vadose zone …
Adsorption Of Halogenated Aliphatic Contaminants By Graphene Nanomaterials: Comparison With Carbon Nanotubes And Granular Activated Carbons, Yang Zhou
All Theses
Graphene nanomaterials are two-dimensional single layer sp2 hybridized carbon atoms densely packed in a hexagonal honeycomb lattice and can be visualized as basic building blocks for fullerenes, carbon nanotubes (CNTs), and graphite. In addition, they are hydrophobic nanomaterials and possess a large specific surface area (SSA), thus they have been evaluated as promising adsorbents to remove synthetic organic compounds (SOCs) from water. As with granular activated carbons (GACs) and CNTs, adsorption behavior of SOCs on graphene depends on the physicochemical properties of the adsorbents (e.g., specific surface area, pore size distribution and surface chemistry), SOCs (e.g., hydrophobicity, molecular size and …
Spatial And Temporal Analysis Of Land Cover Change, Sedimentation And Water Quality In The Lake Issaqueena Watershed, South Carolina, Cassie Pilgrim
Spatial And Temporal Analysis Of Land Cover Change, Sedimentation And Water Quality In The Lake Issaqueena Watershed, South Carolina, Cassie Pilgrim
All Theses
Soil erosion and increased sediment yields within a watershed lead to impaired water quality, decreased availability of wildlife habitat and reduced recreational opportunities. While some sedimentation occurs naturally within a water system, most erosion processes are the result of anthropogenic activities across a landscape, namely changes in land use and land cover (LULC). This study was conducted to determine temporal and spatial sedimentation trends in the Lake Issaquena watershed using sonar logging equipment, geographic information systems (GIS) and limited hydrologic data from the Soil Conservation Service (1941 and 1949). Sediment deposition was analyzed in relation to several key factors that …