Engineering Commons^™

Constrained Multi-Group Project Allocation Using Mahalanobis Distance, Abdulaziz Saud Alkabaa

Doctoral Dissertations

Optimal allocation is one of the most active research areas in operation research using binary integer variables. The allocation of multi constrained projects among several options available along a given planning horizon is an especially significant problem in the general area of item classification. The main goal of this dissertation is to develop an analytical approach for selecting projects that would be most attractive from an economic point of view to be developed or allocated among several options, such as in-house engineers and private contractors (in transportation projects). A relevant limiting resource in addition to the availability of funds is …

Ecology Of Organohalide-Respiring Dehalococcoides Mccartyi: Corrinoid Cofactor-Related Community Interactions And Controls Over Strain Selection, Burcu Şimşir

Doctoral Dissertations

Organohalides such as tetrachloroethene (PCE) and trichloroethene (TCE) are among the most prevalent toxic groundwater contaminants. Remediation of organohalide-contaminated sites has high priority, and efficient and cost-effective remedies are needed to prevent environment and human exposure through contaminated water. Bacterial organohalide-respiration plays a major role in organohalide detoxification. Dehalococcoides mccartyi (Dhc) are key mediators in bioremediation, since only Dhc strains have been documented in complete detoxification of chlorinated ethenes to benign ethene. Dhc depends on other microorganisms in the environment for essential growth requirements (e.g., hydrogen and vitamins). For successful implementation of the reductive dechlorination to remediate contaminated …

Bioremediation Of Chlorinated Ethenes: Ph Effects, Novel Dechlorinators And Decision-Making Tools, Yi Yang

Doctoral Dissertations

Chlorinated solvents have been widely used in different areas of modern society. Usage of these chlorinated solvents was not necessarily accompanied with proper handling and disposal of these hazardous compounds, which caused a variety of environmental problems and continues to affect human health. Remediation of chlorinated ethenes contaminated sites has high priority for state regulators and site owners. Among the available treatment technologies, bioremediation shows great promise as a cost-effective corrective strategy for a variety of environmental pollutants. Prerequisites are that the microbiology involved in contaminant degradation and geochemical factors, such as pH, are understood, so that bioremediation technologies can …

Potential Emissions And Exposures Of Toxic Organics From Storage Tanks For Chemical Additions In Hydraulic Fracturing: A Modeling Approach, Huan Chen

Doctoral Dissertations

Hydraulic fracturing has promoted the exploitation of natural gas in the United States (U.S.). However, the storing and emptying of chemical additives in hydraulic fracturing wells may pose adverse effects through inhalation exposures. Based on the information about hydraulic fracturing fluids, this study investigated: 1) water volumes used to mix chemical additives for making up the hydraulic fracturing fluids; 2) chemical species, concentrations and their degradability in the hydraulic fracturing fluids; 3) emissions of organics from chemical storage tanks; and 4) the occupational inhalation exposures by toxic and organic vapors.

Results shows for 80,047 wells fractured between 2008 and 2014 …

Transit Preferential Treatments At Signalized Intersections: Person-Based Evaluation And Real-Time Signal Control, Yashar Zeiynali Farid

Doctoral Dissertations

Efficient public transportation has the potential to relieve traffic congestion and improve overall transportation system performance. In order to improve transit services, Transit Preferential Treatments (TPT) are often deployed to give transit vehicles priority over other vehicles at an intersection or along a corridor. Examples of such treatments are exclusive bus lanes, queue jumper lanes, and signal priority strategies. The objective of this study is threefold: 1) perform a person-based evaluation of alternative TPTs when considered individually and in combination, 2) develop a bus travel time prediction model along a signalized arterial, and 3) develop a real-time signal control system, …

The Fate Of Haloacetonitriles In Drinking Waters, Yun Yu

Doctoral Dissertations

The fate of HANs in drinking waters from their precursors in natural waters to their degradation products in consumers’ tap were systematically investigated in this study. Combined amino acids were proved reactive with chlorine to form DCAN under typical drinking water conditions. However, the rate of DCAN formation from bound aspartyl residues was much slower compared to free aspartic acid. The key to DCAN formation from combined amino acids was a chlorine-induced peptide degradation process, which slowly degraded the peptide backbone to continuously produce reactive amine functional groups at the N-terminal end. Particularly, when an N-terminal aspartyl residue …

Detailed Study Of Integral Abutment Bridges And Performance Of Bridge Joints In Traditional Bridges, Brooke H. Quinn

Doctoral Dissertations

Integral Abutment Bridges (IABs) are jointless bridges in which the superstructure is cast monolithically with its substructure. Eliminating expansion joints from the superstructure reduces corrosion of bridge elements that typically result from leaking joints in traditional bridges. IABs have proven to be cost effective for both construction and life-cycle analysis. As a result, they are the standard single span highway bridge of choice by the majority of State Departments of Transportation (DOTs) across the country. Despite the widespread use of these bridges, there are no uniform guidelines in place. Factors such as pile orientation, design assumptions, maximum span length, skew …

Integrated Urban Metabolism Analysis Tool (Iumat), Nariman Mostafavi

Doctoral Dissertations

A number of tools are available today for simulating different aspects of urban activity, but these efforts are fragmented and do not effectively reflect the interrelationships between very diverse groups of urban sectors and resource flows. There is a critical need for robust and reliable urban metabolism analysis tools that integrate socio-economic elements of urbanization and physicality of the built environment into evaluating sustainability in cities. This dissertation outlines the development of an Integrated Urban Metabolism Analysis Tool (IUMAT) that dynamically measures the environmental impacts of land cover, transportation, and consumption of energy, water and materials employing a holistic framework. …

Predictive Modeling Of Riverine Constituent Concentrations And Loads Using Historic And Imposed Hydrologic Conditions, Mark Hagemann

Doctoral Dissertations

This research was principally concerned with the task of quantifying dissolved and suspended constituents carried in river water when direct measurements are not available. This is a question of scientific and societal relevance, and one with a long history of study and a great deal of remaining difficulty. The traditional approach to estimating these quantities, linear regression models (LMs), suffers from poor flexibility and high subsequent bias in many applications. This research applied semiparametric generalized additive models (GAMs), a more flexible class of regression models, evaluated their performance in various locations and conditions, and applied them in a proactive modeling …

The Stability Of Ferrate(Vi) In Water And Its Impacts On Disinfection Byproduct Precursors, Yanjun Jiang

Doctoral Dissertations

Ferrate has been proposed as an alternative pre-oxidant in drinking water treatment for many years. Despite extensive studies that examined ferrate oxidation of specific contaminants, little research has been done on the impacts of ferrate in raw waters that include natural organic matter (NOM) and bromide, and that are also treated with coagulants and chlorine. The future of ferrate as a potable water treatment chemical depends on its ability to achieve adequate disinfection while minimizing the formation of disinfection byproducts (DBPs) under these realistic scenarios. In this work, laboratory-scale treatment studies were conducted to (1) clarify the stability of ferrate …

Proactive Assessment Of Climate Change And Contaminant Spill Impacts On Source Water Quality, Lillian C. Jeznach

Doctoral Dissertations

Managing the water quality of surface drinking water sources has become an increasingly difficult task for water suppliers due to increased watershed urbanization and climate change. Changes in source water quality may affect public perceptions, treatment effectiveness, and ultimately costs to treat water to drinking standards. Although there are increased threats to current and future drinking water quality, current approaches to managing these threats are typically reactionary. Prior detailed modeling efforts of hypothetical events that may impair raw water quality allow for an understanding of constituent fate and transport, including potential maximum concentrations and travel times to the drinking water …

Lattice Boltzmann Methods For Wind Energy Analysis, Stephen Lloyd Wood

Doctoral Dissertations

An estimate of the United States wind potential conducted in 2011 found that the energy available at an altitude of 80 meters is approximately triple the wind energy available 50 meters above ground. In 2012, 43% of all new electricity generation installed in the U.S. (13.1 GW) came from wind power. The majority of this power, 79%, comes from large utility scale turbines that are being manufactured at unprecedented sizes. Existing wind plants operate with a capacity factor of only approximately 30%. Measurements have shown that the turbulent wake of a turbine persists for many rotor diameters, inducing increased vibration …

3d Multi-Scale Behavior Of Granular Materials Using Experimental And Numerical Techniques, Andrew Michael Druckrey

Doctoral Dissertations

Constitutive modeling of granular material behavior has generally been based on global response of laboratory-size specimens or larger models with little understanding of the fundamental mechanics that drive the global response. Many studies have acknowledged the importance of micro-scale and meso-scale mechanics on the constitutive behavior of granular materials. However, much knowledge is still missing to develop and improve robust micromechanical constitutive models. The research in this dissertation contributes to this knowledge gap for many potential applications using novel experimental techniques to investigate the three-dimensional (3D) behavior of granular materials. Critical micromechanics measurements at multiple scales are investigated by combining …

Modeling Choice Problems With Heterogeneous User Preferences In The Transportation Network, Mahyar Amirgholy

Doctoral Dissertations

Users of transportation systems need to make a variety of different decisions for their trips in the network, while their objective is to keep the generalized costs of their own trips minimized. In the transportation network, there is a diversity of different factors that can influence the decisions of the users, while the relative importance of these factors varies among the heterogeneous users with different trip purposes. Nonetheless, the cumulative result of the individual decisions of the users seeking to minimize their costs according to their own preferences leads to the user equilibrium condition in which no one can reduce …

Experimental And Numerical Evaluation Of A New Composite Pressure Pipe For A Trenchless Rehabilitation Technology, Xuanchen Yen

Doctoral Dissertations

The information presented in this dissertation is based on research work conducted at Trenchless Technology Center (TTC) at Louisiana Tech University. This work was performed through a contract with China University of Geoscience (CUG) for a gas company. China's gas pipelines need replacement or rehabilitation after 15 to 30 years of service. China's gas industry is looking for suitable techniques to transfer into their market.

When compared to conventional excavation pipeline renewal or replacement methods, there are obvious advantages of TRT for gas pipelines that can impact the triple bottom-line of economic, social and environmental benefits. An introduction of TRT …

Response Of Microbial Community Structure To Clay Flocculation Of Harmful Algal Blooms, Chunyi Chen

Doctoral Dissertations

Harmful algal blooms are cosmopolitan and can produce extremely dangerous toxins that can sicken or kill people and animals, and create dead zones in the water. The U.S. economic loss caused by algal blooms is $82 million every year. Clay-based flocculation techniques have been developed to mitigate algal blooms; however, the potential impacts on the microbial community are poorly understood. This dissertation includes multi-scale experiments (Jar, field, microcosms) to study the response of microbial community structure and function to clay flocculation of algal blooms.

Jar tests of removal of Microcystis aeruginosa by chitosan and two types of commercially available clays …

A Vulnerability Framework For Assessing The Risks To Water Supply Systems Under Climate Uncertainty In The Urban Northeastern United States, Sarah Whateley

Doctoral Dissertations

The northeastern United States is not commonly considered a drought prone region. Yet there are increasing pressures on water utilities throughout the region that constrain their ability to supply reliable water. These include new constraints on water withdrawals and requirements to release additional water for ecological purposes. Finally, there is the emerging concern associated with climate change. The vulnerability of any particular system, however, is not easily assessed, as it is dependent on a variety of factors that go beyond simple changes in precipitation and temperature. These include the size of the watershed, the volume of storage, required releases, and …

Modeling Interactions Between Human Factors And Traffic Flow Characteristics, Chaoqun Jia

Doctoral Dissertations

To serve research needs for traffic flow model development and highway safety enhancement, we model interactions between human factors and traffic flow character- istics, this topic includes methods on collecting data, modeling impacts of parameters on flow, and calibrating parameters on observed data. An example of successful traf- fic data collection is NGSIM data, which contains location, speed, and acceleration information of vehicles. An algorithm was designed to match and extract vehicles’ trajectory records, and utilize the extracted information for pattern recognition of lane changing maneuvers. This algorithm reads records from an NGSIM data set, pick out vehicles executing lane …

Investigation Of Effluent Nitrogen Derived From Conventional Activated Sludge (Cas) And Biological Nutrient Removal (Bnr) Systems And Its Impact On Algal Growth In Receiving Waters, Heonseop Eom

Doctoral Dissertations

The main objective of this research was to evaluate the effects of effluent nitrogen from conventional activated sludge (CAS) and biological nutrient removal (BNR) processes on eutrophication in receiving estuaries. To investigate differences in effluent nitrogen from CAS and BNR processes, lab-scale wastewater treatment systems having identical influent were operated under controlled conditions. This reactor study showed that the BNR system decreased nitrogen discharge by removing dissolved inorganic nitrogen (DIN) from wastewater but generated more effluent dissolved organic nitrogen (DON) than did the CAS system. The transition of treatment conditions from anoxic to oxic within the BNR process facilitated the …

Adaptive Route Choice In Stochastic Time-Dependent Networks: Routing Algorithms And Choice Modeling, Jing Ding-Mastera

Doctoral Dissertations

Transportation networks are inherently uncertain due to random disruptions; meanwhile, real-time information potentially helps travelers adapt to realized traffic conditions and make better route choices under such disruptions. Modeling adaptive route choice behavior is essential in evaluating Advanced Traveler Information Systems (ATIS) and related policies to better provide travelers with real-time information. This dissertation contributes to the state of the art by estimating the first latent-class routing policy choice model using revealed preference (RP) data and providing efficient computer algorithms for routing policy choice set generation. A routing policy is defined as a decision rule applied at each link that …

Innovative Techniques For Seismic-Resistant Bridge Columns Under Ground Motion Excitations, Ayman A. Moustafa

Doctoral Dissertations

“This dissertation provides innovative alternative solutions for replacing conventional reinforced concrete columns. The proposed columns displayed enhanced seismic resistance and properties compared to their counterpart conventional columns. Two main techniques were followed and proposed to develop seismic-resistant columns. The first technique utilized rubberized concrete to internally enhance energy dissipation and damping. Materials testing of rubberized concrete with scrap tire replacement of fine aggregates were performed to evaluate its dynamic properties. Shaking table testing of a rubberized concrete column was performed and the behavior was compared to that of the conventional one. The rubberized column showed an increase of 16% in …

Rehabilitation And Strengthening Of Reinforced Concrete Members Using A Fiber Reinforced Cementitious Matrix Composite, Zena Riyadh Aljazaeri

Doctoral Dissertations

“Externally bonded fiber reinforced cementitious matrix (FRCM) for structural members was tested and evaluated as a new class of composite material for repairing and strengthening infrastructures. In comparison with fiber reinforced polymer (FRP) composites, FRCM composite has a superior high temperature resistance and great compatibility with concrete substrates. Experimental investigation is ongoing in the United States to evaluate the structural and durability performance of FRCM composite to be implemented in field applications. This experimental program consisted of testing 12 strengthened reinforced concrete (RC) beams to study the fatigue and flexure performance under environmental exposure and sustained stress, 10 strengthened RC …

Static And Dynamic Characterization Of Tied Arch Bridges, John Edward Finke

Doctoral Dissertations

"Tied arch bridges have been designed and constructed since the late 19th century. With their open vista owing to minimalist features tied arch bridges continue to appeal the public. Tied arch bridges are both aesthetic and economical alternates to long span bridges holding a place in the hierarchy of major bridges. They fit in a niche between viable and economical plate girder spans and short cable stayed bridge spans. There are several variations of the tied arch with the most common form being those having vertical hangers, stiff tie girders and slender arch ribs. This tied arch variation is examined …

Composite Confinement Systems For Rc Column Repair And Construction Under Seismic Loads: Concept, Characterization And Performance, Mostafa Fakharifar

Doctoral Dissertations

"This study aims at developing, characterizing and validating an integrated composite confinement system of conventional jackets for: (1) repair and retrofit of existing bridge columns; and (2) construction of new bridge columns, subjected to earthquake excitations.

A new composite steel confinement jacket was proposed by combining a thin steel sheet and prestressing strands as a hybrid jacket, incorporating active and passive confining pressure on damaged RC columns. Both experimental and analytical studies were conducted to understand the performance and effectiveness of the proposed repair method. The experimental study involved two 1/2-scale lap-spliced deficient RC bridge columns originally tested to failure …

Kinetic Energy Harvesting Mechanism For Vortex Drop Structures, Mungtra Chusilp

Doctoral Dissertations

Energy recovery from wastewater is gaining significance as utilities work toward achieving energy neutrality and sustainability in their wastewater collection and treatment systems. In this dissertation, kinetic energy harvesting mechanism for vortex drop structures found within the municipal waste and storm water conveyance systems is presented. There are thousands of sewer drop structures installed across the U.S. carrying billions of gallons of sewage each year. A custom micro water turbine is developed in this research which could be retrofitted within the existing drop shafts to harvest the excessive kinetic energy available. This dissertation presents the conceptual design and analysis of …

Microwave Material Characterization Of Alkali-Silica Reaction (Asr) Gel In Cementitious Materials, Ashkan Hashemi

Doctoral Dissertations

"Since alkali-silica reaction (ASR) was recognized as a durability challenge in cement-based materials over 70 years ago, numerous methods have been utilized to prevent, detect, and mitigate this issue. However, quantifying the amount of produced ASR byproducts (i.e., ASR gel) in-service is still of great interest in the infrastructure industry. The overarching objective of this dissertation is to bring a new understanding to the fundamentals of ASR formation from a microwave dielectric property characterization point-of-view, and more importantly, to investigate the potential for devising a microwave nondestructive testing approach for ASR gel detection and evaluation. To this end, a comprehensive …

Geotechnical State-Of-The-Art In Guatemala -- Ground Stabilization, Fernando Rafael Callejas Benitez

Doctoral Dissertations

"History provides an understanding of the present and in a way, a guide for the future. The state-of-the-art is often referred to as a snapshot of the most significant works and contributions made in a field of study; In this case the focus is on Guatemalan geotechnical engineering. This study presents a comprehensive description of the different events that impulse geotechnical engineering in Guatemala.

As part of the description of the state-of-the-practice an investigation of the different human (engineers/contractors) and physical resources (laboratories/field equipment) and their capabilities are presented. An overview of the civil engineering programs is presented. Then, the …