Engineering Commons^™

Sustainable Underground Reactive Barrier To Attenuate Contaminants From Agricultural Drainage, Yuchuan Fan

Doctoral Dissertations

Denitrifying bioreactor (DNBR) has become a popular edge-of-field practice applied to reduce nitrate over the Mississippi river and to prevent a downstream hypoxic zone occurring at the Gulf of Mexico. Despite widespread field and laboratory studies, fewer investigations have been directed toward a systematic means of evaluating the nitrate removal performance achieved by various filling materials, abiotic factors, and other critical parameters. Our ultimate goal is to improve the nitrate removal by choosing the optimum fill materials and operate under optimal conditions, meanwhile, modeling the DNBR by critical variables. This study begins by establishing a global database. Forty filling materials …

Towards Modeling Projectile Penetration In Dry And Multiphase Granular Materials, Mohmad Mohsin Thakur

Doctoral Dissertations

The present work aims at developing and validating numerical modeling strategies in granular materials impacted by a projectile. The focus is on two regions: (a) near-field: region near the tip and along the path of a projectile where comminution of grains is significant, (b) intermediate-field: region far from the projectile where grain-scale interactions are important but stresses are not high enough to cause crushing of the grains.

A novel framework has been introduced and validated wherein particle shape captured using X-ray CT imaging was incorporated in FEM simulations using shell elements for simulating triaxial boundary value problems. The results indicate …

Exploring Potential Impacts Of Connected And Automated Vehicle Technologies, Iman Mahdinia

Doctoral Dissertations

Connected and automated vehicle technologies have the potential to significantly improve transportation system performance. In particular, advanced driver-assistance systems (ADAS), such as adaptive cruise control (ACC), cooperative adaptive cruise control (CACC), pedestrian crash prevention (PCP) system, and advanced automated collision notification (ACN) system may lead to substantial improvements in performance by decreasing driver inputs and taking over control of the vehicle. The main questions that might arise are 1) how we can quantify the potential environmental and safety impacts of these technologies and 2) what the potential for these technologies is to address some of the important transportation-related problems. Due …

A Connectivity Framework To Explore The Role Of Anthropogenic Activity And Climate On The Propagation Of Water And Sediment At The Catchment Scale, Christos Giannopoulos

Doctoral Dissertations

Anthropogenic disturbance in intensively managed landscapes (IMLs) has dramatically altered critical zone processes, resulting in fundamental changes in material fluxes. Mitigating the negative effects of anthropogenic disturbance and making informed decisions for optimal placement and assessment of best management practices (BMPs) requires fundamental understanding of how different practices affect the connectivity or lack thereof of governing transport processes and resulting material fluxes across different landscape compartments within the hillslope-channel continuum of IMLs. However, there are no models operating at the event timescale that can accurately predict material flux transport from the hillslope to the catchment scale capturing the spatial and …

A Multilevel Study Of Driving Behavior And System Performance- Harnessing Large-Scale Naturalistic Driving And Conventional Safety Data, Amin Mohammadnazar

Doctoral Dissertations

The performance of a transportation system highly depends on the drivers’ behavior because driving behavior is one of the main causes of traffic accidents and one of the key factors in fuel consumption and vehicle emissions studies. Specifically, the focus of this dissertation is on aggressive driving who not only put their selves and others at risk but also contribute more to greenhouse gas emissions. Recently, the development of advanced sensors, connected vehicles (CVs), location-based services (LBS) provided unprecedented access to new high-resolution microscopic-level data which can be used to evaluate and monitor instantaneous driving behavior and safety performance of …

Tuned Mass Damper, Ruichen Guo

EURēCA: Exhibition of Undergraduate Research and Creative Achievement

Abstract

My research aims to design a tuned mass damper for a model structure. In the real world, tuned mass dampers are designed to limit the motion of the building when it is subjected to an external excitation, such as an earthquake or hurricane. The design of the mass damper involves determining the mass, stiffness of the spring, and the dimensions of the mass. Once the tuned mass damper is fabricated, I will conduct experimental testing to identify the effectiveness of the tuned mass damper to control the response of a four-story model building. I expect that the mass damper, …

Metabolomics, Genomics And Transcriptomics Unravel Fluoroalkane Metabolism In Pseudomonas Sp. Strain 273., Yongchao Xie

Doctoral Dissertations

Fluorinated organics have been developed and produced for various applications in the industrial, military, medical and agrochemical fields; they are now emerging as persistent organic pollutants with demonstrated adverse health impacts on mammals, including humans. The high bond dissociation energy of C-F bond hinders microbial degradation and defluorination. The present work demonstrates Pseudomonas sp. strain 273 can utilize the 1-fluoroalkanes (C₇ to C₁₀ and C₁₄) and 1,10-difluorodecane (DFD) as the sole carbon source in the presence of oxygen. In this study, fluorine mass balance analysis determined that the majority (> 90%) of the fluorine from the …

Impact And Application Of Real-Time Control On Stormwater Systems, Aaron A. Akin

Doctoral Dissertations

Stormwater control measures (SCMs) such as dry extended detention basins and wet ponds are common practices implemented by engineers and designers to mitigate the impact of stormwater runoff. These practices are designed based on historical rainfall data to attenuate runoff to pre-development conditions and, once they are installed, are unable to adapt to changing rainfall patterns or watershed restoration objectives. To solve these climate resiliency issues, several studies were conducted which investigated the impact of retrofitting such systems with a controllable outlet to increase or change detention times during rainfall events along with the novel instrumentation and methodologies necessary for …

Identifying And Assessing Bacterial Contamination In Stormwater Runoff And Receiving Streams, Songyi Liu

Doctoral Dissertations

Stormwater runoff has been recognized as a significant non-point source of pollution responsible for serious ecological impacts. Microbial pollutants represent one of the major contaminants of concern in stormwater runoff and the receiving streams. Traditionally, fecal indicator bacteria (FIB) have been used extensively to assess the microbial quality of water, particularly the extent of fecal contamination in water. However, the application of FIB as indicators of microbial contamination bears known disadvantages of cultivation-dependent techniques, such as the inability to identify the majority of microbial populations that are not amenable to cultivation under laboratory conditions. The effectiveness of a cultivation-independent sequencing …

Terrestrial Laser Scanning Technology For Measuring Streambank Retreat Along East Fork Poplar Creek And Calculating The Effect On Mercury Release., José L. Martínez Collado

Masters Theses

Mercury (Hg) is a globally distributed inorganic pollutants of human concern. The high toxicity is mainly related to the capacity of Hg species to accumulate and biomagnify along aquatic food webs. Along East Fork Poplar Creek (EFPC), erosion represents the principal mercury input into the local waters, eventually reaching humans through the food chain. This research project aimed to monitor streambank erosion along a mercury-contaminated creek using Light Detention and Ranging (Lidar) technology and erosion pins. A Terrestrial Laser Scanner (TLS) was used to generate high-resolution point clouds from August 2020 to January 2021 across nine streambank locations to detect …

Effect Of Radiation On Bond Behavior Between Concrete And Steel Bar: Development Of Experimental Protocol, Mohammed Abdelrahman

Masters Theses

There is a need to assess the effect of radiation on the behavior of bond strength between steel reinforcement and concrete. However, there is geometrical constraints in the cylindrical capsule which limit the size of concrete samples. Thus, developing a protocol to produce pullout sample and a test setup is needed.

A protocol for fabricating high-precision concrete samples with embedded \#2 steel bar has been developed based on the results of an experimental program. A pullout system has also been developed to investigate the bond activity of concrete and steel. This research looks at two different aggregate sizes 3/8 inch …

Dissolved Organic Carbon And The Potential Role To Stream Acidity In The Great Smoky Mountains National Park, Jason R. Brown

Masters Theses

A substantial societal shift towards environmental awareness has focused research efforts on the impacts of pollution on natural landscapes. Improvements to pollutant regulations and technology have resulted in sizeable reductions of atmospheric deposition of anthropogenic acids, especially nitrates and sulfates, which has altered the role of these ions in the environment. As such, understandings of environmental chemistry dynamics have required regular updating.

Through the National Park Service Vital Signs monitoring program, increases in precipitation pH observed in Great Smoky Mountains National Park (GRSM) has been attributed to the reduction of inorganic acid concentrations. Unfortunately, these improvements have not been uniformly …

Design And Experimental Evaluation Of A Small-Scale Buckling Restrained Brace Analog, Lindsay K. Helferich

Masters Theses

In the event of an earthquake, structures experience large lateral loads that can lead to weak story mechanisms and result in premature building collapse. Strongback braced frames (SBF) are a type of seismic force resisting system that aim to evenly distribute horizontal loads up the height of the building to mitigate this failure mechanism. Previous research shows that SBFs are a promising way to better design for seismic demands, but these systems have not been fully explored to best exploit the design space. This work is a part of a project that aims to provide both numeric and experimental verification …

Microscopic And Image Processing Characterization Of Aggregates To Predict Asr Expansion Potential Of Concrete, Ammar Elfatih Abdelssamd Elhassan

Doctoral Dissertations

Preventing ASR occurrence in new concrete structures requires reliable and quick methods to identify reactive aggregates and to evaluate proper mitigation alternatives. The current accelerated mortar-bar expansion tests (ASTM C 1260 or ASTM C1567) and the concrete prism expansion test (ASTM C 1293) have been reported to have several limitations. Assessment of the extend of ASR damage in existing affected structures requires more understanding on how ASR expansion and damage develop in field conditions such as under confinements and under relatively slow rate of ASR reaction.

The significance of ASR expansion rate and bi-axial restrain on concrete degradation has been …

The Performance Impacts Of Real-Time Control On Bioretention, Padmini P. Persaud

Doctoral Dissertations

Bioretention is a green infrastructure practice used to restore natural hydrologic regimes and improve stormwater quality. Extreme weather combined with demands for treatment of a growing number of priority pollutants has put a strain on these systems, making meeting performance goals difficult. The addition of smart stormwater technology has the potential to help address these issues as more control is provided to modify internal conditions and optimize sometimes conflicting outcomes. The use of real-time control is tested in this research to determine how bioretention performance is impacted by this technology. Column studies incorporating forecasts and historic rainfall were used to …

Using Survey Data To Understand Ridesourcing In Tennessee: Who, Where, When, And Why?, Cassidy Kilmer Crossland

Masters Theses

With companies like Uber and Lyft leading the way, ridesourcing has grown and continues to grow in popularity in the United States since its introduction just over ten years ago. While research on this new transportation mode has largely focused on national level trends and studies of large metropolitan areas, little has been written about its impacts in smaller and mid-sized cities and states. This paper aims to understand the socioeconomic characteristics and travel behavior trends of those using ridesourcing in less studied regions, using Tennessee as a case study. This thesis has three parts: a literature review of past …

Quantifying Tree Canopy Contributions To Stormwater Runoff Reductions In Urban Watersheds Of The Southeastern United States, Matthew C. Howard

Masters Theses

Urban stormwater is a major contributor to surface water degradation in the United States, prompting cities to invest in ways to naturally capture, store, and slowly release runoff through “Green Infrastructure” (GI). One often overlooked potential contributors to stormwater management are urban trees, an integral part of a given city’s GI. Interception is of particular interest and describes a tree’s ability to capture and store rainfall, reducing the volume of stormwater that can degrade urban streams during storm events. While rainfall interception for full canopy, forested environments is well studied, limited research is available that characterizes the interception of open-grown …

Bioretention Cell Performance Under Shifting Precipitation Patterns Across The Contiguous United States, Matthew Weathers

Masters Theses

As climate change produces shifts in precipitation patterns, communities will need to understand how the performance of green stormwater infrastructure (GSI) may be impacted. Bioretention cells are one of the most commonly implemented forms of GSI for their ability to reduce peak discharge and filter pollutants and are a vulnerable component of stormwater infrastructure. Projections in future climate indicate that bioretention cells may be at risk of losing their existing function due to deviations in precipitation frequency and intensity. General circulation models (GCMs) downscaled to regional climate models (RCMs) can provide climate change projections at a high spatial resolution but …

Site Development Services At Mcghee Tyson Airport, Luke A. Edwards, Tyler Bomar, Scott Cole, Samuel Enders, Matthew Dearborn

Chancellor’s Honors Program Projects

No abstract provided.

Approximation Of The Time Rate Of Consolidation For Hydraulically Placed Fine Coal Refuse Using A Variable Coefficient Of Consolidation Method, Cyrus Jedari, Eric Drumm, Angelica Palomino

Faculty Publications and Other Works -- Civil & Environmental Engineering

Terzaghi’s consolidation theory assumes strain in soil due to applied overburden pressure is small, and permeability and thus the coefficient of consolidation (C_v) remain constant during consolidation. Although valid for soft soil consolidation, the C_v for hydraulically placed slurry materials with low solids content may change significantly during the consolidation process as the material transitions from a slurry to a solid. In this study, a spatial and temporal variable C_v was used to predict the time rate of consolidation of fine coal refuse placed in an impoundment as a slurry. The results suggest the variable …