Engineering Commons^™

Drivers’ Hazard Avoidance During Vehicle Automation: Impact Of Mental Models And Implications For Training, Ganesh Pai Mangalore

Doctoral Dissertations

Advanced Driver Assistance Systems (ADAS) are vehicle automation systems that have become more accessible and prevalent in vehicles in recent years. But the introduction of such technologies introduces new human factors challenges. Past literature suggests that users of vehicle automation lack the necessary and appropriate knowledge about their automation system. This may play a negative role in their hazard avoidance abilities when driving with automation features. Improving mental models and knowledge could generally lead to safer interactions with vehicle automation systems, but any effort to develop hazard avoidance skills when driving with vehicle automation is impeded by the lack of …

Low-Shrinkage Fiber-Reinforced Concrete For Infrastructure Construction And Rehabilitation, Jingjie Wei

Doctoral Dissertations

"The aim of this study is to develop two classes of low-shrinkage high-performance concrete (HPC): fiber-reinforced super workable concrete (FR-SWC) for infrastructure construction and fiber-reinforced self-consolidating concrete (FR-SCC) for repair applications. HPC with excess content of shrinkage mitigation materials (SMMs), including shrinkage-reducing admixture (SRA), superabsorbent polymer (SAP), and expansive agent (EA) has a detrimental effect on mechanical performance. These classes of HPC were optimized to reduce shrinkage, enhance mechanical properties, and improve durability. The effect of fiber type (macro synthetic fiber, MSF; 5D steel fiber, 5D; 80% 3D + 20% short steel fibers; STST), SMMs, and plastic viscosity on bond …

Comprehensive Investigation Of Using Tire-Derived Aggregate In Chip Seal Subjected To Various Traffic And Environmental Conditions, Alireza Pourhassan

Doctoral Dissertations

"Chip seal is one of the most cost- and performance-effective pavement preservation treatments commonly used in the United States. Using crumb rubber obtained from scrap tires as a partial or full replacement for mineral aggregate has been proposed as a sustainable solution to reduce the negative environmental impacts of scrap tire accumulation and excessive consumption of natural resources. However, there was no data available regarding the performance of rubberized chip seal under traffic loads and environmental conditions. An extensive study using laboratory specimens and conditioning as well as field implementation and assessments were conducted to bridge this gap. Different traffic …

A Structure From Motion Photogrammetric Method For Continuously Measuring And Tracking The Deformations Of Soils During Triaxial Testing, Xiaolong Xia

Doctoral Dissertations

"Measuring soil deformation characteristics during triaxial testing is an important part of characterizing the stress-strain behavior of both saturated and unsaturated soils. The total and local deformations and volume changes of a soil specimen are indispensable parameters that need to be measured and are of great significance for understanding volume change and shear strength characteristics of the soil. Over the past several decades, numerous efforts have been made to measure the soil deformations during triaxial testing. However, it remains a great challenge for researchers to measure the volume-changes of unsaturated soils due to the existence of the air phase.

This …

Enhanced Bioretention Modeling At The Catchment-Scale: An Integrated Drainmod-Urban And Swmm Approach, Ghada Diab

Doctoral Dissertations

Bioretention systems are increasingly being adopted in stormwater management as an effective measure to promote infiltration and restore more natural hydrology in urbanized watersheds. Given the significant financial investment in these practices, reliable bioretention models are necessary to predict the effectiveness of these practices prior to installation. One such model, DRAINMOD-Urban (DM-Urban), was recently developed to produce hydrographs with a high temporal resolution at the site-scale, showing substantial promise during initial testing. However, the dataset used for initial testing was limited, consisting of one bioretention area with minimal occasions of overflow. Additionally, DM-Urban is an input-heavy model and there is …

Transportation System Performance And Traveler Behavior In The Context Of A Systemwide Shock: Applications Of Data Science Toward A Sustainable Future, A. Latif Patwary

Doctoral Dissertations

The COVID-19 pandemic, a systemwide shock, has left a long-lasting and significant impact on transportation systems. It has contributed to a shift in travel behavior, with many people turning to work from home (WFH) and online shopping. This shift has led to a reduction in vehicular travel. However, the pandemic witnessed increased crash fatalities despite a reduction in overall crashes, disproportionately affecting disadvantaged communities (DACs). The main question arising from these pandemic-related issues is what we can learn to improve transportation systems and shape future travel behavior. Therefore, this dissertation aims to investigate how the transportation system changed during COVID-19 …

Exploring Soil Microbial Dynamics In Southern Appalachian Forests: A Systems Biology Approach To Prescribed Fire Impacts, Saad Abd Ar Rafie

Doctoral Dissertations

Prescribed fires in Southern Appalachian forests are vital in ecosystem management and wildfire risk mitigation. However, understanding the intricate dynamics between these fires, soil microbial communities, and overall ecosystem health remains challenging. This dissertation addresses this knowledge gap by exploring selected aspects of this complex relationship across three interconnected chapters.

The first chapter investigates the immediate effects of prescribed fires on soil microbial communities. It reveals subtle shifts in porewater chemistry and significant increases in microbial species richness. These findings offer valuable insights into the interplay between soil properties and microbial responses during the early stages following a prescribed fire. …

3d Experimental Studies Of Temperature And Crystallographic Effects On Creep And Strength In Rock Salt, Amirsalar Moslehy

Doctoral Dissertations

Salt domes utilization as storage reservoirs in the energy sector has led to extensive studies on rock salt’s mechanical and geothermal behavior. These important facilities’ safety and serviceability rely on understanding rock salt’s compressive strength and creep behavior under various loading directions, water contents, in-situ stresses, and temperatures. Despite numerous studies on rock salt’s mechanical behavior in the literature, there are still many unanswered questions about rock salt’s behavior. This dissertation was aimed at utilizing state-of-the-art experimental techniques such as 3D synchrotron micro-computed tomography (SMT) and 3D x-ray diffraction (3DXRD) along with hundreds of compression and creep experiments to enhance …

Effect Of Seawater And Temperature Upon Carbon Fiber/Vinyl Ester (Cfve) Composites And Its Constituents, Vivek Chawla

Doctoral Dissertations

An experimental and computational investigation has been carried out to: (1) develop micromechanical characterization techniques for polymeric composites and (2) evaluate the effects of seawater and temperature upon the micro- and macro-response of the carbon fiber vinyl ester composites (CF/VE). Compression properties degradation due to short-term and long-term exposure to seawater is evaluated. A 12-16 % reduction in compression strength is observed due to long-term exposure to seawater, which is attributed to a decrease in interfacial shear strength (IFSS) due to long-term exposure to seawater. The developed Push-out methodology is used to characterize the IFSS. The presented approach consistently yields …

Functional Cementitious Composites With Micro-Sized Particulate Fillers For Additive Construction And Energy-Efficient Buildings, Adam Brooks

Doctoral Dissertations

With a growing energy demand, the development of sustainable and energy efficient building materials is growing rapidly. Numerous researches have focused on low carbon footprint construction materials, high-performance thermal insulations, high-performance façade, and thermal energy storage. Among these, the development of functional cementitious composites has attracted significant attention due to its potential utilities in building energy reduction and decarbonatization efforts. For example, fly ash cenospheres have been used as micro-size lightweight fillers to achieve low density and thermal conductivity. The use of phase change materials (PCM) in concrete has been studied to answer energy demands. While their inclusion into concrete …

Steel Deck Diaphragms: Characterizing The Hysteretic Behavior Of Light Gage Steel, Screw-Fastened, Support And Sidelap Connections And The Influence Of Support Connections On The Stability Behavior Of Panels, Divyansh Kapoor

Doctoral Dissertations

Steel deck diaphragms are planar structures that serve as critical components of a metal building’s lateral force-resisting system. These can be found in walls, floors, and roofs of metal buildings and aid with the lateral stability of the structure. The diaphragm design process involves the selection of materials, deck geometry, connections, and connection detailing across the steel panels. The American Iron and Steel Institute’s AISI S310 and Steel Deck Institutes DDM04 both provide design guidance on the selection and detailing of materials and fasteners for the applicable limit states of connections and stability of the panels. Both design codes provide …

Integrated Modeling And Monitoring For A Healthy And Sustainable Building Environment, Yifang Xu

Doctoral Dissertations

The transmission of airborne diseases indoors is a significant challenge to public health. Buildings are hotspots for viral transmission, which can result in adverse effects on human health and quality of life, especially considering that individuals spend approximately 87% of their time indoors. The emergence of the COVID-19 pandemic has highlighted the importance of considering health aspects during the development of sustainable built environments. Consequently, maintaining a healthy, sustainable, and comfortable built environment represents a major challenge for facilities management teams. However, research on the infection risks associated with emerging pandemics is still in its infancy, and the effectiveness of …

Responsive Building Envelope For Grid-Interactive Efficient Buildings – Thermal Performance And Control, Yawen He

Doctoral Dissertations

The building sector accounts for 30% of total energy consumption worldwide. Responsive building envelopes (or RBEs) are one of the approaches to achieving net-zero energy and grid-interactive efficient buildings. However, research and development of RBEs are still in the early stages of technologies, simulation, control, and design. The control strategies in prior studies did not fully explore the potential of RBEs or they obtained good performance with high design and deployment costs. A low-cost strategy that does not require knowledge of complex systems is needed, while no studies have investigated online implementations of model-free control approaches for RBEs. To address …

Improving Mobility And Safety In Traditional And Intelligent Transportation Systems Using Computational And Mathematical Modeling, Shahrbanoo Rezaei

Doctoral Dissertations

In traditional transportation systems, park-and-ride (P&R) facilities have been introduced to mitigate the congestion problems and improve mobility. This study in the second chapter, develops a framework that integrates a demand model and an optimization model to study the optimal placement of P&R facilities. The results suggest that the optimal placement of P&R facilities has the potential to improve network performance, and reduce emission and vehicle kilometer traveled. In intelligent transportation systems, autonomous vehicles are expected to bring smart mobility to transportation systems, reduce traffic congestion, and improve safety of drivers and passengers by eliminating human errors. The safe operation …

Advanced Air Quality Management With Machine Learning, Cheng-Pin Kuo

Doctoral Dissertations

Air pollution has been a significant health risk factor at a regional and global scale. Although the present method can provide assessment indices like exposure risks or air pollutant concentrations for air quality management, the modeling estimations still remain non-negligible bias which could deviate from reality and limit the effectiveness of emission control strategies to reduce air pollution and derive health benefits. The current development in air quality management is still impeded by two major obstacles: (1) biased air quality concentrations from air quality models and (2) inaccurate exposure risk estimations

Inspired by more available and overwhelming data, machine learning …

Functionalizing Three-Dimensional Superhydrophobic Materials, Li He

Doctoral Dissertations

Traditional bulk superhydrophobic materials are usually characterized by high porosity, low fracture toughness, and extremely low strength due to the low surface energy on the internal surface. Therefore, it is very challenging to achieve a bulk superhydrophobic material with high strength and mechanical durability. This dissertation presents an experimental study of strengthening a superhydrophobic siloxane using carbon-based nanomaterials, emphasizes the effects of microscale dispersion and macroscale distribution of reinforcing graphene on the uniformity and strength of the composite, studies the impact factors on the water adsorption for hydrophilic and hydrophobic materials, and applies chemical modification modify the surface of clay …

Water Resources Planning Under Deep Uncertainty For Physically, Socially, And Politically Complex Systems, Sarah St. George Freeman

Doctoral Dissertations

Water supply systems, particularly those of large cities, are complex systems linking supply, regulatory and distribution infrastructure, and points of use. Despite their physical complexities, it is infrequent that full supply, distribution, end use, and feedbacks therein are considered in an integrated manner. These complex systems-of-systems face large uncertainties related to physical aspects such as degradation of infrastructure, changing demand, and climate variability and change. Though great, such physical uncertainties often pale in comparison to the those related to the human systems in place to manage them and yet uncertainty in the decision-making landscape is often grossly simplified in our …

Promoting Enhanced Decision-Making And Proactive Management For Modularization In The Construction Industry Using Risk-Based Approach, Analytical Hierarchy Process, And Graph Theory, Mohamad Abdul Nabi

Doctoral Dissertations

"Modularization is an approach that can potentially mitigate many of the current construction industry’s challenges. Despite the documented advantages of modularization, the industry is still not able to capitalize on its full potential and benefits. The latter is due to the outdated decision-making models that may not reflect the multiple factors involved in modular construction, the unique source of risks associated with modular construction methods, need for continuous improvement, and complex contractual requirements and disputes. As such, the goal is to promote the use of modularization in the construction industry by enhancing decision-making and proactive risk management. The associated objectives …

A Study On Early Age Properties Of Concrete For Precast And 3d Printing, Debalina Ghosh

Doctoral Dissertations

Concrete is the second-most consumed material, leading the global Portland cement production of 4.1 billion tons in 2020 and 5-8% of global Carbon dioxide (CO₂) emission annually. As with any other material and practice, the construction industry is also ever-changing to meet market demand, evolving technology, and resource limitation. In the case of concrete construction, one of the main concerns is the lack of automation. In the last few decades, some new construction methods have risen to address this concern. Some of these economic and successful practices are precast construction, self-compacting concrete (SCC), and 3D printing of concrete(3DPC). …

Evaluating Impacts Of Shared E-Scooters From The Lens Of Sustainable Transportation, Nitesh Shah

Doctoral Dissertations

As the popularity of shared micromobility is increasing worldwide, city governments are struggling to regulate and manage these innovative travel technologies that have several benefits, including increasing accessibility, reducing emissions, and providing affordable travel options. This dissertation evaluates the impacts of shared micromobility from the perspective of sustainable transportation to provide recommendations to decision-makers, planners, and engineers for improving these emerging travel technologies.

The dissertation focuses on four core aspects of shared micromobility as follows: 1) Safety: I evaluated police crash reports of motor vehicle involving e-scooter and bicycle crashes using the most recent PBCAT crash typology to provide a …

Fundamental Investigation Of Interaction Between Moisture And Asphalt-Aggregate Systems, Rui Xiao

Doctoral Dissertations

Moisture-induced damage is one of the most common forms of flexible pavement distress which directly causes or exacerbates pavement failure. The intrusion of moisture into the asphalt pavements reduces the overall mechanical properties of the locking structures and gives rise to one or more of the visible forms of distress such as raveling, stripping, permanent deformation and fatigue cracking. This doctoral study is aimed at understanding the detrimental action of water on the asphalt-aggregate systems and the damage mechanism by multi-technique investigation. A thermodynamics framework was considered to characterize the properties of asphalt mix ingredients as well as the engineering …

Emerging Trends In Bus Ridership In The United States, Abubakr Ziedan

Doctoral Dissertations

Public transit ridership in the United States was declining even before the COVID-19 pandemic. Many different factors affect transit ridership levels, and the recent declines in ridership across the country make it critical to assess which factors are causing declines and which may help to increase ridership. Therefore, this dissertation seeks to quantify the impact of three emerging factors on bus ridership: shared electric scooters (e-scooters), new fare payment technologies and policies, and the COVID-19 pandemic.

This dissertation analyzed the impacts of shared e-scooters on bus ridership. This was investigated at the route level in Louisville, KY, and Nashville, TN, …

A Study Of Readiness For Transportation Electrification And Automation Focusing On Safety And Future Adoption, Steve Lee

Doctoral Dissertations

Transportation electrification and automation are growing societal trends and considered promising pathways to enhance the safety, mobility, efficiency, and sustainability of the surface transportation system. At this early stage of transportation electrification and automation, one of the most critical issues is whether and to what extent people are willing to adopt electric vehicle (EV) and automated vehicle (AV) technologies in the future. Another critical issue, especially concerning transportation automation, is how to thoroughly ensure the safety of automated driving performance to resolve safety concerns about AVs, which is one of the key challenges to AV adoption. In this regard, the …

Predicting Water Quality Vulnerability Under Climate Change With Machine Learning, Khanh Thi Nhu Nguyen

Doctoral Dissertations

Water quality deterioration is a global and pervasive issue due to pollution caused by industrialization, urbanization, agriculturalization, and human population growth in the modern era. This issue is even more challenging in the context of climate change due to warming temperatures and the intensification of precipitation. Therefore, assessing the potential impacts of climate change on water quality is a concern. Assessment is necessary so that planners can prepare for and reduce the negative impacts on water quality. At present, climate change impact assessment frameworks are relatively adolescent. Most studies rely on climate projections from General Circulation Models for simulations of …

Experimental Investigation Of Clay Aggregate And Granular Biofilm Behavior, Tao Jiang

Doctoral Dissertations

Clay minerals are a class of phyllosilicates as the major solid constituents in cohesive fine-grained soils (e.g., clays). Owing to their tiny size (i.e., < 2 μm), high aspect ratio, and active surface properties that inherit from the geological process, clay minerals can extensively interact with other suspended matter (e.g., exoployemers, microorganisms) and dissolved ions via the process of flocculation and aggregation, resulting in the formation of larger, porous cohesive particulate aggregates or flocs. Such a complex mechanism of microscale particle interaction generates significant challenges for understanding the bulk clay behavior as a particulate system. In order to better characterize the flocculation and aggregation of clay minerals under various stimuli and to understand the underlying mechanism of particle interactions, particle/aggregate size kinetics of flocculated suspensions of illite, a representative 2:1 clay mineral abundant in marine soils, are studied with varied ionic strength induced by monovalent salt (NaCl), pH, and hydrodynamic shearing in the first phase of this research. Furthermore, a new statistical data binning method termed “bin size index” (BSI) was employed to determine the probability density function (PDF) distributions of flocculated illite suspensions. The statistical results demonstrate that the size kinetics of flocculated illite suspensions is chiefly controlled by the face-to-face and edge-to-face interparticle interactions under the mutual effects of ionic strength and pH, while the hydrodynamic shearing has minimal effects on the variation of particle size groups. In the second phase of this research, the mechanics of clay aggregates are studied using an innovative measurement technique and analytical approach. Individual clay minerals prepared with different mineralogy and salinities are tested via unconfined compression, which shows that the increasing ionic strength can improve the strength and stiffness of clay aggregates, which are further affected by the mineralogical compositions and dominant microfabric in different water chemistry. In the final phase of this research, a collaborative study with an environmental engineer on an NSF CAREER project was conducted to investigate the mechanical behavior of macroscale, light-induced oxygenic granules (biofilm aggregates) using the same technique and analytics developed for the individual clay aggregates. The findings are expected to provide reference values to subsequent studies and engineering practices associated with the water treatment process.

Lateral Response Of Cold-Formed Steel Diaphragms With Variable Sheathing, Hernan Castaneda

Doctoral Dissertations

Cold-formed steel (CFS) framed buildings and subsystems have demonstrated safe and reliable performance while under lateral and seismic loads. Combined with their structural efficiency, this makes CFS-framed buildings popular choice even in high seismic zones. However, due to the complexity in response of CFS members and their interaction in subsystem and system levels, more research needs to be conducted to better understand the overstrength in the system, as well as the contribution of non-structural components to the overall response of the building. The lateral force resisting system (LFRS) of CFS framed buildings consist primarily of shear walls and diaphragms. The …

Optimizing Transportation Systems With Information Provision, Personalized Incentives And Driver Cooperation, Sayeeda Ayaz

Doctoral Dissertations

Poor performance of the transportation systems has many detrimental effects such as higher travel times, increased travel costs, higher energy consumption, and greenhouse gas emissions, etc. This thesis optimizes the transportation systems by addressing the traffic congestion problem and climate change impact resulting from the inefficient operation of these systems. I first focus on the key player of the transportation systems e.g., human being/traveler, and model travelers' route choice behavior with real-time information. In this study, I define looking-ahead behavior in route choice as a traveler's taking into account future diversion possibilities enabled by real-time information in a network with …

Abiotic And Biotic Degradation Of Bisphenols, Yanchen Sun

Doctoral Dissertations

Bisphenol A (BPA), as well as its substitutes bisphenol S (BPS) and bisphenol AF (BPAF), are high production volume chemicals and potential endocrine disruptors. The oxidized manganese (Mn) species, soluble Mn(III) and solid Mn(IV) (i.e., MnO₂), are typically generated in Mn-cycling driven by Mn-oxidizing bacteria and Mn-reducing bacteria. MnO₂ is a strong oxidant capable of oxidizing a variety of organic contaminants including bisphenols. Soluble Mn(III) commonly occurs near oxic-anoxic interfaces and is an important environmental oxidant. Mn(III) is also associated with both biogenic and synthesized MnO₂. However, the effect of Mn(III) on the degradation of …

Investigating The Blending Mechanism And Strength Development Of 100% Hot In-Place Recycled Asphalt Mixtures, Yuetan Ma

Doctoral Dissertations

The current tendency in the asphalt paving industry is to increase the utilization of recycled asphalt pavement (RAP). Hot in-place recycling (HIR) is a promising approach to consume 100% RAP from the existing pavement for pavement surface rehabilitation in the field. However, some concerns remained regarding the utilization of HIR techniques in pavement rehabilitation: 1. Whether it is cost-effective to apply the in-place recycling techniques to pavement rehabilitation compared to the conventional HMA surface milling & filling? 2. How to improve the performance of the asphalt mixtures with HIR technique? 3. How much RAP binder can be available for coating …

Deep Learning-Based Robotic Perception For Adaptive Facility Disinfection, Da Hu

Doctoral Dissertations

Hospitals, schools, airports, and other environments built for mass gatherings can become hot spots for microbial pathogen colonization, transmission, and exposure, greatly accelerating the spread of infectious diseases across communities, cities, nations, and the world. Outbreaks of infectious diseases impose huge burdens on our society. Mitigating the spread of infectious pathogens within mass-gathering facilities requires routine cleaning and disinfection, which are primarily performed by cleaning staff under current practice. However, manual disinfection is limited in terms of both effectiveness and efficiency, as it is labor-intensive, time-consuming, and health-undermining. While existing studies have developed a variety of robotic systems for disinfecting …