Engineering Commons^™

Evaluation Of Impacts On Delay, Cycle-Length Optimization, Control Types, And Peak-Hour Factor With The Randomness Of Traffic, Jan-Mou Li

Doctoral Dissertations

Some basic concepts about traffic which are correct in theory may be misinterpreted in practice. Such misinterpretations may lead to a different direction from the ideal operation. This four-part dissertation is designated to examine fundamental concepts in traffic operation, and to validate the impact of randomness on control delays, cycle-length optimization, control types, and the peak-hour factor.

Control delays experienced by drivers is a critical performance measure on interrupted-flow traffic which involves movements at slower speeds and stops on intersection approaches, as vehicles move up in the queue or slow down upstream of an intersection. Since the basic term of …

Structural And Economical Impacts Of Heavy Truck Loads On Bridges, Xiang Zhou

Doctoral Dissertations

The study included in this dissertation assesses the strength, serviceability, and economic impact of overweight trucks on Louisiana bridges. Truck load configurations FHWA 3S2 and FHWA 3S3 were applied to bridge models that were originally designed for HS20-44 truck configuration to determine the effects of heavy truck loads on bridges. Behaviors of bridge components including bridge girder, deck, and diaphragm were evaluated separately.

AASHTO linear approach and finite element analysis were employed to evaluate bridge girder behaviors under the heavy truck load. Bridge models with different geometric configurations were considered. Both short term and long term effects on simple span …

Study On Infrastructure Materials Using Neutron Radiography And Diffraction, Xin Luo

Doctoral Dissertations

Advanced nondestructive neutron technology has been utilized to study fundamental issues in the Lost Foam Casting (LFC) process and in the mechanical behavior of infrastructure materials.

Time lapsed neutron radiography combined with digital image processing was used to investigate the real-time LFC process. Behavior and characteristics of the pyrolysis front in the LFC processes were discussed. Evidence shows that neutron radiography offers new insights into the pyrolysis front and the dynamics of the processes involved with the casting. Behavior and characteristics of the pyrolysis front and the molten metal interface in the LFC processes were revealed. The proposed approach will …

Modeling The Quorum Sensing Signaling Regulatory Network In Vibrio Fischeri, Ling Yan

Doctoral Dissertations

Quorum sensing is a mechanism by which bacteria can sense the levels of signaling molecules and respond by controlling the expression of target genes. The marine bacterium, Vibrio fischeri, has been extensively studied as a model for the quorum sensing mechanism in Gram-negative bacteria. In order to systematically investigate the quorum sensing regulatory network in V. fischeri, a conceptual model was first established based on the existing knowledge. Next, molecular microbiology and bioinformatics techniques were employed to both qualitatively and quantitatively characterize the system. These techniques included the quantification of the 3-oxo-C6-HSL concentrations in the cell culture supernatant …

Uncertainty And Error In Laser Triangulation Measurements For Pipe Profiling, Michael Kenneth Swanbom

Doctoral Dissertations

Underground pipeline infrastructure often receives insufficient attention and maintenance. Those responsible for ensuring the continuing functionality of this infrastructure primarily use subjective information in their decision making, and standards defining the level of damage acceptable before repair or replacement are difficult to implement. Laser pipe profiling is a relatively new technology that has emerged to take a step toward the objective assessment of buried assets. A laser profiler is a device that traverses a section of pipe, taking measurements of radius around the circumference of the inner pipe wall at multiple locations along the length of the pipe. The accuracy …

Position And Orientation Correction For Pipe Profiling Robots, Andrew John Dettmer

Doctoral Dissertations

Sewer pipelines are prevalent, important, valuable, unnoticed, and often in a state of disrepair. Pipeline inspection is essential for effective management of wastewater systems and is now mandated for many municipalities complying with the Governmental Accounting Standards Board Statement 34 and EPA regulations. Pipe inspection robots are routinely used to inspect underground pipelines for cracks, deformations, leaks, blockages and other anomalies to prevent catastrophic failure and to ensure cost effective maintenance and renewal. Most existing pipe inspection robots only collect video footage of pipe condition. Pipe profiling technology has recently been introduced to allow for measurement of the internal coordinate …

The Design And Performance Of Pressure Pipe Liners Under Static And Cyclic Loading, Shanhai Guan

Doctoral Dissertations

Cured-in-place pipe (CIPP), is a widely used trenchless technology. Based on the current liner design method, American Society for Testing and Materials (ASTM) F2207-02, several aspects are studied for the effect on estimating the long-term performance of the liners.

While estimating the liner burst pressure, the effect from host pipe material properties, liner material properties, defect geometry, liner creep properties and loading condition should be considered. The burst pressure calculated based on the existing method is overestimated and this allows an increased risk of structural failure before the expected design life is reached.

Compared with cast-iron, a PVC host pipe …

Field And Laboratory Investigation Of Ozone-Indoor Surface Reactions: Secondary Emissions Inventory And Implications For Indoor Air Quality, Hong Wang

Doctoral Dissertations

"Interfacial chemistry greatly influences human exposure to reactants and products in indoor environments. Emissions of volatile organic compounds, as a result of ozone-surface interactions, can lower an occupant's exposure to ozone, but increase indoor concentrations of odorous and carcinogenic compounds. Therefore, investigation of ozone-surface interactions are necessary for better understanding and controlling exposure to ozone and the products of indoor surface chemistry. In this dissertation, field experiments were conducted in five homes in three seasons to quantify ozone-initiated secondary emission rates (SERs), yields surface reaction probabilities and study their temporal trends"--Abstract, page iv.

Innovative Solutions In Bridge Construction, Rehabilitation, And Structural Health Monitoring, Fabio Matta

Doctoral Dissertations

"This dissertation includes three technical papers that investigate the development of innovative technologies for bridge construction, rehabilitation, and structural health monitoring, respectively, at different stages of the technology transfer process...The research impact is twofold: first is the introduction of promising innovative technologies in development and implementation projects with the direct involvement of forward-thinking industry partners; second is the demonstration of the validity of these technologies on the basis of a rigorous scientific approach"--Abstract, page iv.

The Leaching Behavior Of Arsenic, Selenium And Other Trace Elements In Coal Fly Ash, Tian Wang

Doctoral Dissertations

"The goals of this study are four fold, they are: (1) to investigate the leaching behavior of arsenic and selenium from fly ash as well as their affecting factors; (2) to analyze the speciation of arsenic and selenium in fly ash leachate; (3) to develop a modeling approach to quantify the availability and stability of trace cationic elements in fly ash; (4) to apply this model to describe the leaching/adsorption behavior of arsenic and selenium on fly ash, as well as the calcium effect on arsenic (V) adsorption process"--Abstract, page iv.

Experimental And Analytical Evaluation Of Frp-Confined Large Size Reinforced Concrete Columns, Silvia Rocca

Doctoral Dissertations

"Fiber Reinforced Polymer (FRP) jacketing of Reinforced Concrete (RC) columns, as a rapidly growing strengthening technique, requires appropriate design methods. However, the current available design guides are based on models, in their majority semi-empirical, and calibrated with small-scale plain concrete specimens. These models might not be reliable in predicting the strength and ductility enhancement sought through FRP-confinement in RC columns with geometric and material properties as found in practice. This dissertation presents the research conducted in three technical papers. In the first paper, the performance of 22 FRP-wrapped RC columns of medium- and large-scale is studied. The results of the …