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) …

Mechanics Of Biocell Landfill Settlements, Chamil Hiroshan Hettiarachchi

Dissertations

Prediction of landfill gas generation and settlements are of concerns in design and maintenance of biocell landfills. Accurate settlement prediction is essential for design of piping systems used for the delivery of re-circulated leachate and recovery of landfill gas. Landfill settlement is the result of change in overburden stresses and biodegradation of waste. Biodegradation-induced settlement results from the re-arrangement of waste skeleton in response to the decomposition of waste mass.

Current practice of landfill settlement modeling is predominantly empirical, thus most of the available techniques make no attempt to simulate the real mechanisms of waste settlement. Traditionally compressibility index is …

Utility Of Remote Sensing Data In Retrieval Of Water Quality Consituents Concentrations In Coastal Water Of New Jersey, Ting Yu

Dissertations

Three important optical properties used for monitoring coastal water quality are the concentrations of chlorophyll (CHL), color dissolved organic matter (CDOM) and total suspended materials (TSM). Ocean color remote sensing, a technique to collect color data by detection of upward radiance from a distance (Bukata et al.,1995), provides a synoptic view for determining these concentrations from upwelling radiances. In the open ocean (Case-I), it is not difficult to derive empirical algorithms relating the received radiances to surface concentrations of water quality parameters. In coastal waters (Case-Il), there are serious unresolved problems in extracting chlorophyll concentration because of high concentration of …

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 …

Minimum Velocities For The Suspension Of Fine Sediment In The Green River Canal, Michael W. Stoeber

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

This paper focuses on a canal in the Gunnison Valley, located in central Utah, which diverts water from the sediment-laden Green River. Grain size analyses were performed on sediment samples taken from the canal. These grain size analyses were used to determine the grain size distribution of the fine sediment, classify the fine sediment, and compare the fine sediment to a sediment deposit in the Green River. The critical incipient velocity for the D₅₀ and D₁₀₀ and the critical grain entrainment velocity corresponding to the D₉₅ were determined through flume experimentation. Two methods, developed by prior researchers, …

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 …

Usable Design Of Civil Engineer Information Systems, Gunther Kastenholz

Theses and Dissertations

This research used a case study methodology where one instrument used to collect data was a heuristic usability inspection method. Data was collected from a literature review of pertinent Civil Engineer information system design documents, and conclusions drawn about the existing level of specification of usability engineering principles. The heuristic usability inspection method was used to validate the conclusions drawn through inspection of an information system representative of other Civil Engineer information systems, the Automated Civil Engineer System Personnel Readiness module.

Development And Evaluation Of Lime Mortars For Restoration Of Historic Buildings And Monuments, Tarek Said Mahfouz

Archived Theses and Dissertations

Monuments and historic buildings and sites are regarded as a national treasure of any country. This is particularly true for Egypt that possesses a wealth of historic and heritage buildings covering the entire life span of human civilization. It must be preserved and safeguarded not only as historic evidences but also as works of art. Most of these structures used lime based mortars as binding material. These structures are deteriorating at a rate faster than our ability to renovate them. The repair and rehabilitation of old historic walls and mortars involve a complex interaction of existing and new elements. Engineers …

Behavior Of Structural Concrete Members Strengthened By Composite Fabrics, Jian Chen

Dissertations

The new technique of using Fiber Reinforced Polymer (FRP) materials to repair and strengthen various concrete members is becoming more and more popular in structural retrofitting field. Among all the confining materials, Carbon Fiber Reinforced Polymer (CFRP) fabric jackets are identified as an effective way to enhance the strength and ductility of concrete members due to its superior mechanical properties. This study investigates the detailed structural behavior of confined concrete members using CFRP fabric jackets by both analytical and experimental approaches.

A series of CFRP wrapped concrete cylinder tests were conducted to study the compressive stress-strain behavior for CFRP confined …

Uniaxial And Triaxial Behavior Of High Strength Concrete With And Without Steel Fibers, Xiaobin Lu

Dissertations

This study first presents an extensive experimental research program on the true uniaxial and triaxial compression behavior for both high strength concrete (HSC) and steel fiber reinforced high strength concrete (SFHSC). The experimental study mainly focuses on the octahedral shear stress strain relationship of those two types of concrete, which is adopted as the basis to develop a new incremental constitutive model. Emphasis is also put on the investigation of the variation of tangent Poisson's ratio under not only uniaxial but also triaxial stress conditions. The effect of cyclic loading on this parameter is also addressed.

According to this research, …

Safety Issues Of Red-Light Running And Unprotected Left-Turn At Signalized Intersections, Xuedong Yan

Electronic Theses and Dissertations

Crashes categorized as running red light or left turning are most likely to occur at signalized intersections and resulted in substantial severe injuries and property damages. This dissertation mainly focused on these two types of vehicle crashes and the research methodology involved several perspectives. To examine the overall characteristics of red-light running and left-turning crashes, firstly, this study applied 1999-2001 Florida traffic crash data to investigate the accident propensity of three aspects of risk factors related to traffic environments, driver characteristics, and vehicle types. A quasi-induced exposure concept and statistical techniques including classification tree model and multiple logistic regression were …

Optimization Of An Unstructured Finite Element Mesh For Tide And Storm Surge Modeling Applications In The Western North Atlantic Ocean, Satoshi Kojima

Electronic Theses and Dissertations

Recently, a highly resolved, finite element mesh was developed for the purpose of performing hydrodynamic calculations in the Western North Atlantic Tidal (WNAT) model domain. The WNAT model domain consists of the Gulf of Mexico, the Caribbean Sea, and the entire portion of the North Atlantic Ocean found west of the 60° W meridian. This high resolution mesh (333K) employs 332,582 computational nodes and 647,018 triangular elements to provide approximately 1.0 to 25 km node spacing. In the previous work, the 333K mesh was applied in a Localized Truncation Error Analysis (LTEA) to produce nodal density requirements for the WNAT …

Three Dimensional Modeling Of Wekiva Springshed With Wash123d, Sandeep Paladagu

Electronic Theses and Dissertations

This thesis presents a three-dimensional groundwater modeling of Wekia springshed in central Florida using a numerical model, WASH123D. Springs have historically played an important role in Florida's history. The Wekiva River is a spring-fed system associated with about 19 springs connected to the Floridan aquifer. With increased urbanization and population growth in this region, there has been an increased strain on the water levels of Floridan aquifer which is a major source of potable water. Maintaining groundwater recharge to the aquifer is a key factor of the viability of the regional water supply as well as Wekiva ecosystem. Hence, the …

Finite Element Evaluation Of The Effects Of Lateral Anchorage Strips On The Behavior Of Cfrp-Strengthened Rc Beams, Jose Javier Perez

Electronic Theses and Dissertations

In this thesis, a fully nonlinear finite element study of the flexural behavior of doubly reinforced concrete beams strengthened using different Carbon Fiber Reinforced Polymer (CFRP) composite strengthening configurations has been carried out. Prior to the study, a total of six beams were constructed, pre-cracked, strengthened and tested to failure under a four-point loading condition (Zhao and O'Riordan-Adjah, 2004). Then, for the purpose of this thesis work, detailed three dimensional finite element models were created not only to correlate the results obtained from the experiments, but also to predict the load capacity, failure modes and crack pattern of reinforced concrete …

Applying Log-Linear Models And Gis To Study The Safety Of Pedestrians And Bicyclists : A Case Study Of Orange County School Children, Sai Srinivas Chundi

Electronic Theses and Dissertations

Abstract Pedestrian /bicycle safety of school children has been a growing menace that has been attracting attention from transportation professionals, school boards, media and the community all over the country. As such there has been a necessity to identify critical variables and assess their importance in pedestrian/bicycle crashes occurring in and around school zones. The current study is an endeavor in this direction. The literature review identified some studies that were conducted on school zone safety related to pedestrian/bicyclist crashes. Most of the studies pertained to crashes with all age groups. There have been few studies with emphasis only on …

Estimation Of Hybrid Models For Real-Time Crash Risk Assessment On Freeways, Anurag Pande

Electronic Theses and Dissertations

Relevance of reactive traffic management strategies such as freeway incident detection has been diminishing with advancements in mobile phone usage and video surveillance technology. On the other hand, capacity to collect, store, and analyze traffic data from underground loop detectors has witnessed enormous growth in the recent past. These two facts together provide us with motivation as well as the means to shift the focus of freeway traffic management toward proactive strategies that would involve anticipating incidents such as crashes. The primary element of proactive traffic management strategy would be model(s) that can separate 'crash prone' conditions from 'normal' traffic …

The Effect Of Tidal Inlets On Open Coast Storm Surge Hydrographs: A Case Study Of Hurricane Ivan (2004), Michael Salisbury

Electronic Theses and Dissertations

Florida's Department of Transportation requires design storm tide hydrographs for coastal waters surrounding tidal inlets along the coast of Florida. These hydrographs are used as open ocean boundary conditions for local bridge scour models. At present, very little information is available on the effect that tidal inlets have on these open coast storm tide hydrographs. Furthermore, current modeling practice enforces a single design hydrograph along the open coast boundary for bridge scour models. This thesis expands on these concepts and provides a more fundamental understanding on both of these modeling areas. A numerical parameter study is undertaken to elucidate the …

Countermeasures Against Scour At Bridge Abutments, Hua Li

Dissertations, Master's Theses and Master's Reports - Open

Scour at bridge abutments can cause damage or failure of bridges and result in excessive repairs, loss of accessibility, or even death. To mitigate abutment scour, both clear-water and live-bed laboratory experiments in a compound channel were performed using parallel walls and spur dikes as countermeasures, respectively. In addition, collars were tested under clear-water conditions only. It was found that both parallel walls and spur dikes can efficiently protect the abutment from scour provided that they are properly designed. Design guidelines were discussed for both countermeasures. Preliminary clear-water tests of collars as countermeasures against scour showed some promising results although …

Benchmark Studies For Structural Health Monitoring Using Analytical And Experimental Models, Jason Lee Burkett

Electronic Theses and Dissertations

The latest bridge inventory report for the United States indicates that 25% of the highway bridges are structurally deficient or functionally obsolete. With such a large number of bridges in this condition, safety and serviceability concerns become increasingly relevant along with the associated increase in user costs and delays. Biennial inspections have proven subjective and need to be coupled with standardized non-destructive testing methods to accurately assess a bridge's condition for decision making purposes. Structural health monitoring is typically used to track and evaluate performance, symptoms of operational incidents, anomalies due to deterioration and damage during regular operation as well …

Modeling, Simulation And Analysis Of Multi-Barge Flotillas Impacting Bridge Piers, Peng Yuan

University of Kentucky Doctoral Dissertations

The current design code governing bridge structure resistance to vessel impact loads in the U.S. is the American Association of State Highway and Transportation Officials' (AASHTO) Guide Specification and Commentary for Vessel Collision Design of Highway Bridges. The code stipulated method, based on Meir-Dornberg's equivalent static load method, is usually not warranted because of insufficient data on the impact load histories and wide scatter of the impact force values. The AASHTO load equations ignore certain fundamental factors that affect the determination of impact forces and bridge dynamic responses. Some examples of factors that are omitted during standard impact force …

A New Paradigm Of Modeling Watershed Water Quality, Fan Zhang

Electronic Theses and Dissertations

Accurate models to reliably predict sediment and chemical transport in watershed water systems enhance the ability of environmental scientists, engineers and decision makers to analyze the impact of contamination problems and to evaluate the efficacy of alternative remediation techniques and management strategies prior to incurring expense in the field. This dissertation presents the conceptual and mathematical development of a general numerical model simulating (1) sediment and reactive chemical transport in river/stream networks of watershed systems; (2) sediment and reactive chemical transport in overland shallow water of watershed systems; and (3) reactive chemical transport in three-dimensional subsurface systems. Through the decomposition …

Implementation Strategies For Real-Time Traffic Safety Improvements On Urban Freeways, Jeremy Harvey Dilmore

Electronic Theses and Dissertations

This research evaluates Intelligent Transportation System (ITS) implementation strategies to improve the safety of a freeway once a potential of a crash is detected. Among these strategies are Variable Speed Limit (VSL) and ramp metering. VSL are ITS devices that are commonly used to calm traffic in an attempt to relieve congestion and enhance throughput. With proper use, VSL can be more cost effective than adding more lanes. In addition to maximizing the capacity of a roadway, a different aspect of VSL can be realized by the potential of improving traffic safety. Through the use of multiple microscopic traffic simulations, …