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Experimental And Theoretical Investigation Of Adsorption Of Water Vapor On Carbon Nanotubes, Pyoungchung Kim

Doctoral Dissertations

The adsorption of water in nanoporous materials becomes an important issue in the environmental fate and applications when one considers the practical use of these materials as adsorbents for hazardous organic compounds in the diverse environments.

In this study, the complexity of water-SWNTs interaction was investigated by morphological and chemical characterization techniques, by gravimetric adsorption measurement and by interpretation of experimental adsorption isotherms by fitting to several existing semi-empirical water adsorption models. Commercially available SWNTs samples were measured for chemical and physical characterization such as O% by x-ray photoelectron spectroscopy, I_D/I_G by Raman spectroscopy and surface and …

Structural Health Monitoring And Damage Evaluation Of Full-Scale Bridges Using Triaxial Geophones: Controlled In-Situ Experiments And Finite Element Modeling, William S. Ragland Ii

Doctoral Dissertations

The purpose of this study was to evaluate the effectiveness of various vibration-based damage detection methods using triaxial vibration records obtained using inexpensive geophones during in-situ, full-scale, damaged bridge tests.

Geophones are passive directional sensors and much cheaper than accelerometers which are typically used for structural vibration measurements. However, magnitude and phase errors associated with a geophone’s output must be corrected for if they are implemented in bridge monitoring systems. This research discusses correction procedures for magnitude and phase errors associated with geophones. A simply supported beam was analyzed to verify that the correction procedures and modal parameter identification procedures …

Development Of Dbt Bridge System With Continuous Joints For Accelerated Construction, Lungui Li

Doctoral Dissertations

Speed of construction has become a critical issue to minimize disruption of traffic and commerce. One of the promising systems for accelerated bridge construction is the use of the decked bulb-tee (DBT) girders for the bridge superstructure. An integral deck that is precast and prestressed with the girder provides benefits of rapid construction along with improved structural performance. However, the limited research and concerns about the use of longitudinal joints as well as intermediate diaphragms limit widespread of the DBT bridge system.

This dissertation presents a study of the continuous for both moment and shear transfer longitudinal joint detail and …

Stream Channel Stability And Channel Evolution In A Rapidly Urbanizing, Ridge-And-Valley Watershed, Beaver Creek, Knox County, Tennessee, Francis Bartholomew Keaney

Masters Theses

In Tennessee, sedimentation is among the leading causes of stream impairment. Excessive loads of alluvium are detrimental to the ecological health and human use of these resources. Sediments in streams have many sources, but there is evidence that stream bank erosion is a major contributing factor. Development and urbanization in a stream’s watershed will have impacts on the concentration of stream sediment because the increase in the area covered by impervious surfaces, which reduces initial abstraction and retention times. This, in turn will increase the peak storm water discharge and sediment carrying capacity. If the stream channel cannot accommodate these …

Geotechnical Site Characterization Using Multi-Channel Analysis Of Rayleigh And Love Waves, James David Lane, Jr.

Masters Theses

The Multi-Channel Analysis of Surface Waves (MASW) is a technique in which surface waves can be analyzed to determine soil shear wave velocity profiles with depth. The shear wave velocity of soil can be used to calculate the shear modulus, which is an important geotechnical engineering parameter. Site surveys were conducted and analyzed located at a location on the flood plain of the Tennessee River. The flood plain consists of a thin layer of soil above rigid (Knox Dolomite) bedrock and exhibited strong stratification. Three different aspects of MASW data acquisition and analysis are presented in the study. The first …

Impact Of Larger Diameter Strands On Aashto/Pci Bulb-Tees, Jayaprakash Vadivelu

Masters Theses

This thesis consists of the analytical study and the experimental investigation of larger diameter strands in AASHTO Type I girders. The main purpose of this study was to verify that the 2 inch minimum spacing recommended by ACI 318-08 and AASHTO (2008) can be used for 0.7 inch diameter strands by comparing various effects in girders using 0.7 and 0.6 inch diameter strands. Based on the parametric analysis it was concluded that by using 0.7 inch strands there was a considerable saving in the material. For example, an AASHTO BT-72 with 0.6 inch strand could be replaced with AASHTO BT-54 …

Export Of Carbon, Nutrients And Microbiological Indicators In Beaver Creek Watershed, Tennessee, Si Chen

Masters Theses

Storms are the most important events impacting stream water quality at the watershed-scale. With the goal to develop effective water resource management strategies for the impaired Beaver Creek Watershed in East Tennessee, the impacts of storm events on water quality were assessed by monitoring the intra-storm dynamics of the export of carbon, nutrients, and microbiological indicators (E. coli), which are parameters critical to water quality and ecological functions of the target watershed. The dynamics of carbon export from the Beaver Creek Watershed as represented by dissolved organic carbon revealed distinct carbon transport mechanisms as a function of storm …

Characterizing Episodic Stream Acidification Using A Concentration-Duration-Frequency Methodology In Watersheds Of The Great Smoky Mountains National Park, John Leland Mauney Iii

Masters Theses

Episodic stream acidification occurs as storm events temporarily reduce acid neutralizing capacity and pH. Stream acidification is suspected to have damaging effects on the health of aquatic ecosystems and biota and is dependent on various watershed characteristics such as drainage area, elevation, slope, and surficial geology. Here, a stochastic modeling approach is applied to continuous pH data for multiple stream monitoring sites within the Great Smoky Mountains National Park in order to characterize episodic acidification responses during stormflows for different streams. The approach summarizes voluminous pH data recorded by water quality sondes at 15-minute intervals into concentration-duration-frequency relationships. Unique to …

Structural Behavior Of A Pile Framed Tie Back Retaining Wall, Mieah Dee Turner

Masters Theses

The objective of this research study is to analyze the preliminary structural behavior of a pile framed tie back retaining wall concept created by the Tennessee Department of Transportation (TDOT). Instrumentation is used to measure the forces and moments on the steel piles, loads on the anchors, and the pressure and displacement of the retained soil over time. Data collection for steel pile analysis consisted of the comparison of strain gage readings. Stress values were calculated from the readings and reduced down to an axial and bending force along the pile. Soil pressures that built up behind the wall were …

Coupled Flow Discrete Element Method Application In Granular Porous Media Using Open Source Codes, Feng Chen

Doctoral Dissertations

The flow of fluid through an assembly of particles is of interest to a range of fields such as civil engineering, powder technology, and liquid chromatography. The Discrete Element Method (DEM) is a numerical approximation used to model the interaction of particles and fluid. This study starts with the verification of the open source 3D DEM code (YADE) by investigating simple, one and two-particle contact problems, and DEM results are shown to compare very well with the classical 1D vibration solutions.

2D and 3D simulations of particles flowing through a hopper were then investigated. The stability of the sinkhole repair …

An Investigation Of The Transferability Of Trip Generation Models And The Utilization Of Aspatial Context Variable, Jerry Don Everett

Doctoral Dissertations

The cost of collecting data for travel demand modeling is high and increasing each year. Data collection costs could easily exceed the annual budget of a metropolitan planning organization (MPO) in small or medium-sized area. Many of these agencies borrow or transfer data and/or models from other areas since they cannot afford the cost of collecting local data. This study included two primary research objectives. The first was to test the appropriateness of transferring commonly used trip generation models from one urban area to another under specific circumstances. The second was to improve the transferability of models by including a …

Towards Universality In Automatic Freeway Incident Detection: A Calibration-Free Algorithm, Manoel Mendonca De Castro-Neto

Doctoral Dissertations

Freeway automatic incident detection (AID) algorithms have been extensively investigated over the last forty years. A myriad of algorithms, covering a broad range of types in terms of complexity, data requirements, and efficiency have been published in the literature. However, a 2007 nationwide survey concluded that the implementation of AID algorithms in traffic management centers is still very limited. There are a few reasons for this discrepancy between the state-of-the-art and the state-of the-practice. First, current AID algorithms yield unacceptably high rates of false alarm when implemented in real-world. Second, the complexities involved in algorithm calibration require levels of efforts …

The Influence Of Brick Veneer On Racking Behavior Of Light Frame Wood Shear Walls, Nikola Zisi

Doctoral Dissertations

The racking behavior of an anchored brick veneer – wood frame wall system was investigated analytically. The core wall model simulated a wood frame sheathed with oriented strand board. Brick veneer was then tied to the exterior wall face, and gypsum wallboard sheathing was added on the interior wall face. Two-dimensional linear elastic beam and continuum type elements were used to model these principal wall components. Gap elements were used to prevent sheathing overlap and to model panel bearing at the base. The veneer was supported on compression-only spring elements in the vertical direction and perfectly plastic spring elements in …

Method Of Evaluation For Stream Bed Shear Stress And Sediment Transport Capacity In Urbanizing Watershed: Implications For Stream Restoration, William Cantrell

Masters Theses

In the field of stream restoration, use of a one-dimensional flow model with typical Manning’s n values for an open channel greatly over-predicts bed shear values. This, in turn, incorrectly predicts the size of the mobile fraction on the bed and if used in a bedload transport function over-predicts mass movement of the bed material. This study identified 12 sites for which watershed and reach characteristics were compiled, and bedload sampling was performed. This information was used to produce an empirical relationship between reach pebble count data and an effective Manning’s n value that can be used to produce accurate …

Effect Of Ambient Temperature And Humidity On Aging Of Nanocarbons, Liangcheng Yang

Masters Theses

We researched effect of ambient temperature and humidity on aging of nanocarbons, including carbon nanotubes and fullerenes. We studied physicochemical properties of these nanocarbons stored in ambient conditions (20^oC, 35-55%RH) for 24 months, in 90% relative humidity (RH) environment for 8 months and in 37^oC environment for 13 months. We measured surface area and pore volume of samples by using N₂ adsorption (77K) technique and characterized surface chemistry by using X-Ray photospectroscopy and FT-IR spectroscopy. We also analyzed structural defects with Raman spectroscopy. All tests were conducted periodically.

In ambient condition, we found that nanocarbons …

Experimental Investigation Of Precast Bridge Deck Joints With U-Bar And Headed Bar Joint Details, Samuel Lewis

Masters Theses

This thesis presents the experimental investigation of two joint details for use in precast bridge deck systems. U-bar and headed bar joint details were developed for use in accelerated construction applications. Both details, in practice, would consist of staggered protruding reinforcement that would allow for the anchorage of the precast deck component into the joint. Six specimens containing the joint details were constructed and tested. Three specimens were tested in flexure to simulate the forces that would be experienced in a longitudinal deck joint, and three specimens were tested in tension to simulate the forces that would be experienced in …