Engineering Commons^™

The Rrnat/Rdna Ratio As A Measure Of Nitrite Oxidizing Activity, Shawn A. Hawkins

Doctoral Dissertations

A bench scale nitrification reactor (BSNR) containing nitrite oxidizing bacteria (NOB) of the genus Nitrobacter (» 1 × 10¹⁰/L; 5 - 22% of bacteria) was used to assess the ribosomal RNA transcript (rRNAt) to ribosomal RNA gene (rDNA) ratio as an in-situ nitrite oxidizing activity metric. A quantitative PCR detection system was developed that amplified a 143 base pair sequence within the Nitrobacter spp. 16S - 23S intergenenic spacer region. The resulting real-time PCR (rDNA) and real-time RT-PCR (rRNAt) assays were specific, accurate, and sensitive, requiring three replicate nucleic acid extracts to reliably detect a true 2-fold concentration …

Floating Wim Threshold Concept For Truck Weight Enforcement, Zhongren Gu

Doctoral Dissertations

Weigh stations are the primary weight compliance checkpoints for commercial trucks. In the past several decades, states have used weigh-in-motion (WIM) technology to reduce delay and increase enforcement on overweight vehicles. This study offers a detailed analysis of weigh station systems and presents floating-threshold algorithms to improve the efficiency of WIM equipped weigh stations.

This research evaluates weigh station design and operational parameters using queueing theory and found that WIM technology not only enhances the effectiveness and efficiency of weigh station operations but also largely reduces travel delay for trucking companies. The effects of truck demand, truck weight distribution, static …

Application Of Statistical Methods And Process Models For The Design And Analysis Of Activated Sludge Wastewater Treatment Plants (Wwtps), Jinsheng Huo

Doctoral Dissertations

The purpose of this study is to investigate statistical procedures to qualify uncertainty, and explicitly evaluate its impact on wastewater treatment plants (WWTPs). The goal is to develop a statistical-based procedure to design WWTPs that provide reliable protection of water quality, instead of making overly conservative assumptions and adopting empirical safety factors. An innovative Monte Carlo based procedure was developed to quantify the risk of violating effluent as a function of various design decisions. A simulation program called StatASPS was developed to conduct Monte Carlo simulations combined with the ASM1 model.

A random influent generator was developed to describe the …

Freeway Crash Prediction Models For Long-Range Urban Transportation Planning, Vasin Kiattikomol

Doctoral Dissertations

The need for safety assessment tools for long-range transportation planning was not seriously recognized until the Transportation Equity Act for Twenty First Century (TEA-21) established a requirement related to safety considerations in the planning process of Metropolitan Planning Organizations (MPO). Currently, most MPOs do not assess the safety consequences of alternative transportation systems. The goal of this dissertation is to develop practical tools for assessing safety consequences of freeways in the context of long-range urban transportation plans. Data for freeway segments and crashes were obtained from North Carolina Department of Transportation and Tennessee Department of Transportation. Three different modeling approaches …

Modeling And Analysis Of The Dupont Access Bridge, Naiyu Wang

Masters Theses

This thesis evaluates the lateral wheel load distribution on a two-span experimental highway bridge, examines the continuity of the superstructure over the center pier, and investigates the connection between bridge girders and abutments. Simplified finite element models of the bridge superstructure with different boundary conditions were made during the research to simulate the bridge behavior and verify the field data. Live load distribution factors for moment from the model with a rotational spring connection between bridge girders and abutment correlated well with factors from field measurements, and they were compared with factors from other methods currently in use such as …

Analytical Verification Of The Aci Approach Of Estimating Tensile Strain Capacity Of Mass Concrete, Cristina Diane Seay

Masters Theses

Mass concrete fill is being used for the support of a facility foundation in Oak Ridge, Tennessee. The facility design requires the support foundation to be relatively crack-free in order to attain the shear wave velocity of 6000 fps, which is necessary for acceptable structural behavior during a design basis earthquake. Specifications were developed for use during construction of the support foundation to ensure that the mix design, sequential placement, and curing are performed to standards that would best ensure a relatively crack-free product. The mix design and subsequent placement strategy were developed by using an American Concrete Institute (ACI) …

Effects Of Heavy-Duty Diesel Vehicle Idling Emissions On Ambient Air Quality At A Truck Travel Center And Air Quality Benefits Associated With Advanced Truck Stop Electrification Technology, Guenet Tilahun Indale

Doctoral Dissertations

United States Department of Transportation (DOT) requires truck drivers to rest for 10 hours after every 14 hours of driving. During this time and while waiting for loading and unloading of their trucks, truck drivers idle their engine to provide heat or air conditioning for the cab and sleeping compartment, keep the engine warm during cold climate, and provide electrical power for their onboard appliances. At large truck stops, 200 or more trucks may be idling at the same time. At these truck stops idling emissions can significantly contribute to the concentrations of NOx and PM_2.5 pollutants in the …

Evaluation Of The Dupont Access Bridge, David Pendleton Chapman

Masters Theses

This Thesis describes the evaluation of a experimental steel connection used on the DuPont Access Bridge in New Johnsonville, Tennessee. The bridge has two spans and is designed to act continuously under the dead load. The connection consists of a tension plate bolted to the top flange of the girders at the pier and a wedge plate welded to the bottom flange of the girders. This Thesis also describes the measured and predicted lateral load distribution of the bridge.

Traffic Signal Phase Truncation In The Event Of Traffic Flow Restriction, Scott Glenn Beaird

Masters Theses

This thesis presents a proposed improvement to traffic signal controller logic. The concept consists of truncating a phase on which there is demand but zero or minimal flow due to a restriction of traffic. The logic presented in this thesis recognizes such a flow restriction and, consequently, terminates the phase in favor of a conflicting call for service. The theory of the concept is addressed and methods of implementation are explored.

An experimental analysis was conducted in order to qualify the benefit of the phase truncation concept. This analysis was conducted using the VISSIM simulation software in conjunction with a …

An Evaluation Of Alternative Permissive Periods On Non-Coordinated Phase Performance In Coordinated Traffic Signal Systems, Manoel Mendonca De Castro-Neto

Masters Theses

Currently, there are some concerns regarding coordinated-actuated traffic signal operations. First of all, there is no consistent nomenclature to describe coordination modes. Different traffic signal controller manufacturers use different terminologies and their terms are not necessarily meaningful or intuitive. Actually, one can find inconsistency in the terminology used even by a specific manufacturer just by trying to understand (or decipher) the manual. Secondly, and this might be just a consequence of the first concern, it seems that many traffic engineers and technicians are not aware of the particularities and differences among the coordination modes.

The main purpose of this study …

A Comparison Between The Compressive Strength And The Dynamic Properties Of Concrete As A Function Of Time, Shane Darrel Boone

Masters Theses

The purpose of this study was to examine and compare the correlation between the compressive strength of a mass concrete mix and that concrete’s dynamic properties, specifically, shear wave velocity. Several methods, including static and dynamic tests, were used to determine the concrete’s physical properties of compressive strength, modulus of elasticity, both static and dynamic, and shear wave velocity.

It has been found that, for the specific concrete analyzed, there is a correlation between the compressive strength and dynamic properties as well as a correlation between the static and dynamic moduli. The data found in this study shows that dynamic …