Civil Engineering Commons^™

Using Statistical Learning Approaches To Understand Trends And Variability Of Tornadoes Across The Continental United States, Niloufar Nouri

Dissertations and Theses

The annual frequency of tornadoes during 1950-2018 across the major tornado-impacted states were examined and modeled using anthropogenic and large-scale climate covariates in a hierarchical Bayesian inference framework. Anthropogenic factors include increases in population density and better detection systems since the mid-1990s. Large-scale climate variables include El Niño Southern Oscillation (ENSO), Southern Oscillation Index (SOI), North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), Arctic Oscillation (AO), and Atlantic Multi-decadal Oscillation (AMO). The model provides a robust way of estimating the response coefficients by considering pooling of information across groups of states that belong to Tornado Alley, Dixie Alley, and Other …

Modeling Flow And Nitrate Transport In Karst Groundwater Basins, Yuan Gao

Electronic Theses and Dissertations, 2020-2023

Understanding the groundwater flow in karst aquifers and the effect of best management practices (BMPs) on nitrate decrease in spring discharge is critical for effective management and protection of karst water resources. However, the control on the conduit network's impacts on spring discharge and nitrate concentration is not fully understood, and the cumulative effects of BMP on reducing nitrate in karst groundwater systems have not been evaluated at the basin scale. In this dissertation, a coupled Conduit Flow Process (CFPv2) and Conduit Mass Three-Dimensional (CMT3D) model was applied to evaluate the biosorption-activated media (BAM)-based BMP on nitrate removal in Silver …

Climatic And Topologic Controls On The Complexity Of River Networks, Sevil Ranjbar Moshfeghi

Electronic Theses and Dissertations, 2020-2023

The emergence and evolution of channel networks are controlled by the competition between the hillslopes and fluvial processes on the landscape. Investigating the geomorphic and topologic properties of these networks is important for developing predictive models describing the network dynamics under changing environment as well as for quantifying the roles of processes in creating distinct patterns of channel networks. In this dissertation, the response of landscapes to changing climatic forcing via numerical-modeling and field observations was investigated. A new framework was proposed to evaluate the complexity of catchments using two different representations of channel networks. The structural complexity was studied …

Safety Evaluation Of Innovative Intersection Designs: Diverging Diamond Interchanges And Displaced Left-Turn Intersections, Ahmed Abdelrahman

Electronic Theses and Dissertations, 2020-2023

Diverging diamond interchanges (DDIs) and Displaced left-turn intersections (DLTs) are designed to enhance the operational performance of conventional intersections that are congested due to heavy left-turn traffic volumes. Since drivers are not familiar with these types of intersections, there is a need to evaluate their safety performance to validate their effect, and to estimate reliable and representative Crash Modification Factors (CMFs). The safety evaluation was conducted based on three common safety assessment methods, which are before-and-after study with comparison group, Empirical Bayes before-and-after method, and cross-sectional analysis. Furthermore, since DLTs showed poor safety performance, the study also investigated the operational …

Traffic Speed Prediction And Mobility Behavior Analysis Using On-Demand Ride-Hailing Service Data, Jiechao Zhang

Electronic Theses and Dissertations, 2020-2023

Providing accurate traffic speed prediction is essential for the success of Intelligent Transportation Systems (ITS) deployments. Accurate traffic speed prediction allows traffic managers take proper countermeasures when emergent changes happen in the transportation network. In this thesis, we present a computationally less expensive machine learning approach XGBoost to predict the future travel speed of a selected sub-network in Beijing's transportation network. We perform different experiments for predicting speed in the network from future 1 min to 20 min. We compare the XGBoost approach against other well-known machine learning and statistical models such as linear regression and decision tree, gradient boosting …

Prediction Of Pedestrians' Red Light Violations Using Deep Learning, Shile Zhang

Electronic Theses and Dissertations, 2020-2023

Pedestrians are regarded as Vulnerable Road Users (VRUs). Each year, thousands of pedestrians' deaths are caused by traffic crashes, which take up 16% of the total road fatalities and injuries in the U.S. (FHWA, 2018). Crashes can happen if there are interactions between VRUs and motorized transportation. And pedestrians' unexpected crossings, such as red-light violations at the signalized intersections, would expose them to motorized transportation and cause potential collisions. This thesis is intended to predict the pedestrians' red-light violation behaviors at the signalized crosswalks based on an LSTM (Long Short-term Memory) neural network. With video data collected from real traffic …

The Impacts Of Wave Energy Conversion On Coastal Morphodynamics In A Changing Climate, Cigdem Ozkan

Electronic Theses and Dissertations, 2020-2023

Fossil fuels, i.e., petroleum, natural gas, and coal, are the primary sources of global energy. Studies on the impacts of fossil fuels on climate change have shown the immediate need to reduce greenhouse gas emissions and adopt sustainable alternatives since these emissions result in warmer atmospheric temperatures, ocean acidification, glacier melting, sea level rise, and many other ramifications. In recent years, these alarming results have prompted governments worldwide to develop adaptation strategies for climate change, leading to increased investments in renewable energy resources. Globally, solar energy, wind energy, and hydropower have been the leading sources of renewable energy. Ocean wave …

The Viability Of Organic Dyes In Luminescent Down-Shifting Layers For The Enhancement Of Si Solar Cell Efficiency, Aaron Glenn, Conor Mcloughlin, Hind Ahmed, Hoda Akbari, Subhash Chandra, Sarah Mccormack

Articles

The main energy losses in solar cells are related to spectral losses where high energy photons are not used efficiently, and energy is lost via thermalization which reduces the solar cell’s overall efficiency. A way to tackle this is to introduce a luminescent down-shifting layer (LDS) to convert these high energy photons into a lower energy bracket helping the solar cell to absorb them and thus generating a greater power output. In this paper, lumogen dye Violet 570 has been used as LDS coated films of 10μm and 60μm placed on top of Si solar cells. The dye was incorporated …

Holistic Resilience Quantification Framework Of Rural Communities, Amanda Melendez

Theses and Dissertations--Civil Engineering

Communities need to prepare for anticipated hazards, adapt to varying conditions, and resist and recover rapidly from disturbances. Protecting the built environment from natural and man-made hazards and understanding the impact of these hazards helps allocate resources efficiently. Recently, an indicator-based and time-dependent approach was developed for defining and measuring the functionality and disaster resilience continuously at the community level. This computational method uses seven dimensions that find qualitative characteristics and transforms them into quantitative measures. The proposed framework is used to study the resilience of rural communities’ subject to severe flooding events. Harlan County in the Appalachian region is …

Effect Of Socioeconomic And Demographic Factors Of Driver Residence On Crash Occurrence, Shraddha Sagar

Theses and Dissertations--Civil Engineering

In the U.S., road traffic crashes are a leading cause of death. Crash data from the state of Kentucky shows that the per capita crash rates and crash-related fatalities were higher than the national average for over a decade. In effort to explain why the U.S. Southeast experiences higher crash rates than other regions of the country, previous research has argued the region’s unique socioeconomic provide a compelling explanation. Taking this observation as a starting point, this study examines the relationship between highway safety and socioeconomic characteristics using an extensive crash dataset from Kentucky.

The primary goal of this research …

Modeling Of Incident Type And Incident Duration Using Data From Multiple Years, Sudipta Dey Tirtha

Electronic Theses and Dissertations, 2020-2023

We develop a model system that recognizes the distinct traffic incident duration profiles based on incident type. Specifically, a copula-based joint framework with a scaled multinomial logit model (SMNL) system for incident type and a grouped generalized ordered logit (GGOL) model system for incident duration to accommodate for the impact of observed and unobserved effects on incident type and incident duration. The model system is estimated using traffic incident data from 2012 through 2017 for the Greater Orlando region, employing a comprehensive set of exogenous variables – incident characteristics, roadway characteristics, traffic condition, weather condition, built environment and socio-demographic characteristics. …

A Corridor Level Gis-Based Decision Support Model To Evaluate Truck Diversion Strategies, Samar Younes

Electronic Theses and Dissertations, 2020-2023

Increased urbanization, population growth, and economic development within the U.S. have led to an increased demand for freight travel to meet the needs of individuals and businesses. Consequently, freight transportation has grown significantly over time and has expanded beyond the capacity of infrastructure, which has caused new challenges in many regions. To maintain quality of life and enhance public safety, more effort must be dedicated to investigating and planning in the area of traffic management and to assessing the impact of trucks on highway systems. Traffic diversion is an effective strategy to reduce the impact of incident-induced congestion, but alternative …

Mobility-As-A-Service: Assessing Performance And Sustainability Effects Of An Integrated Multi-Modal Simulated Transportation Network, Mohamed El-Agroudy

Electronic Theses and Dissertations, 2020-2023

Advances in information technology services have seen profound impacts on the state of transport services in the urban traffic environment. Mobility-as-a-Service (MaaS) represents the digital consolidation of users, operators, and public-private managing entities to provide totally comprehensive, integrated trip-making services. Users now enjoy extra flexibility for trip-making with new modal alternatives such as micro-mobility (e.g Lime Bikes, Spin Scooters) and rideshare (e.g. Lyft, Uber). However, current knowledge on the performance and interactive effects of these newer alternative modes is vague if not inconsistent. As such, these effects were studied through micro-simulation analysis of a multi-modal urban corridor in Orlando, Florida. …

Evaluation Of Safety And Mobility Benefits Of Connected And Automated Vehicles By Considering V2x Technologies, Md Hasibur Rahman

Electronic Theses and Dissertations, 2020-2023

The recent development in communication technologies facilitates the deployment of connected and automated vehicles (CAV) which are expected to change the future transportation system. CAV technologies enable vehicles to communicate with other vehicles through vehicle-to-vehicle (V2V) communications and the infrastructure through Vehicle-to-infrastructure (V2I) communications. Since the real-world CAV data is not currently available as of today, simulation is the most commonly used platform to evaluate the future V2X system. Although several studies evaluated the effectiveness of CAVs in a small roadway network, there is a lack of studies analyzing the impact of CAVs at the network level by considering both …

A Deep Learning Approach For Real-Time Crash Risk Prediction At Urban Arterials, Pei Li

Electronic Theses and Dissertations, 2020-2023

Real-time crash risk prediction aims to predict the crash probabilities within a short time period, it is expected to play a crucial role in the advanced traffic management system. However, most of the existing studies only focused on freeways rather than urban arterials because of the complicated traffic environment of the arterials. This thesis proposes a long short-term memory convolutional neural network (LSTM-CNN) to predict the real-time crash risk at arterials. The advantage of this model is it can benefit from both LSTM and CNN. Specifically, LSTM captures the long-term dependency of the data while CNN extracts the time-invariant features. …

Structural Performance Evaluation Of Dynamic Message Signs With Adhesive And Welded Joints, Ibin Amatya

Electronic Theses and Dissertations

The ultimate objective of this study was to determine the structural performance of the Dynamic Message Sign (DMS) bonded with chemical adhesive in terms of ultimate strength and fatigue strength. To achieve this objective, this study first investigated the effects of various parameters, including humidity and temperature on tensile, shear, peel, and cleavage strength through small-scale tests of adhesive specimens with variation in specimen width. The tensile, shear, peel, and cleavage specimens were conditioned in a temperature-humidity controlled chamber prior to its testing. The tensile, shear, peel, and cleavage specimens with different widths were tested according to American Society for …

A Review Of The Second Level Construction Studies Syllabus In Ireland: In Response To A Changing Technological Environment Promoting Digital Construction, Bim Tudublin, Nigel Wearen

Capstone Reports

The zeitgeist of Construction Studies ought to adopt digital construction and work practises. However, legacy is slow to change/adapt, and a lack of awareness persists. From the perspective of the continuing legacy (vocational training) of Construction Studies being linked with industry, this research explores how the subject could evolve to deliver new digital skill sets and to meet the demands of the Architecture, Engineering, and Construction (AEC) sector.A pilot study was undertaken with 24 Transition Year students. The method and content of the study was based on an existing model from the Design Engineering Construction in the UK and was …

Sustainable And Resilient Construction: Current Status And Future Challenges, Niamh Murtagh, Lloyd Scott, Jingli Fan

Articles

The construction industry globally is one of the most environmentally damaging of sectors. Additionally, the resources consumed and the operational energy requirements of buildings are ‘locked-in’, potentially for decades. The Intergovernmental Panel on Climate Change has recognised construction as a sector in which significant improvements can, and indeed must, be made. But the industry is often argued to be unique, in its multiplicity of stakeholders, transient organisational structures, avoidance of risk and impact on society. The current Virtual Special Issue (VSI) sought to bring together a collection of papers on progress and potential for improvement in the construction sector, in …

Corrigendum To “Heavy Metal Ion Detection On A Microspot Electrode Using An Optical Electrochemical Probe” [Electrochem. Commun. 86 (2018) 94–98], Santanu Roy, Abhijeet Prasad, Rahul Tevatia, Ravi Saraf

Mid-America Transportation Center: Final Reports and Technical Briefs

The authors regret to inform an error. Ravi F. Saraf of this pub- lication discloses financial interest in Vajra Instrument as its founder and President. In accordance with its Conflict of Interest policy, the University of Nebraska-Lincoln’s Conflict of Interest in Research Committee has determined that this must be disclosed. The authors would like to apologise for any inconvenience caused.

Seismic Performance Of Mechanically Spliced Bridge Columns Through Analytical Studies, Mathew Ray Lavoy

Electronic Theses and Dissertations

Reinforcement continuity in concrete members is traditionally achieved through lap splicing. Mechanical bar splices are an alternative to traditional lap splices. Mechanical bar splices utilize mechanical devices known as bar coupler to connect the ends of reinforcing bars. Bar couplers are common in accelerated bridge construction applications at non-critical members but are not allowed in the plastic hinge region of bridge columns probably due to a lack of knowledge on how they affect seismic performance of columns. A comprehensive analytical study was carried out to determine how bar couplers used at the base of bridge columns affect: 1) column lateral …

Effects Of Cellulose Nano-Fiber As An Additive On Performance Of Asphalt Binders And Mixes, Marco Paulo Pereira Castro

Electronic Theses and Dissertations

Findings of a study conducted on asphalt binders and mixes modified by addition of cellulose nanofiber (CNF) to evaluate the feasibility of them as an additive is presented in the current thesis. Cellulose Acetate (CA) is an ester of cellulose and is obtained by the reaction of cellulose with acetic anhydride and acetic acid in the presence of sulfuric acid. Due to its high temperature sensitivity, high ductility, large surface area, high strain resistance, and low electrical resistivity, cellulose acetate can be used for several application. The question is if CNF can be used as an additive in the asphalt, …

Safety Design Management Processes To Mitigate Design Errors, Hernan Guadalupe

Walden Dissertations and Doctoral Studies

Some organizations lack processes to mitigate design errors that may result in potential accidents or loss of life during building construction. Managers are concerned about preventing injuries and accidents, which may promote safer working conditions during construction. Grounded in the transformation-flow-value theory of production, the purpose of this qualitative single case study was to explore safety design management processes that managers use to mitigate errors. The participants included 7 members from 1 design firm with business operations in the United States northeastern region. Data were collected from semistructured interviews and company document reviews. Data were analyzed using Yin's 5-phase, where …

Improving Traffic Safety And Efficiency By Adaptive Signal Control Systems Based On Deep Reinforcement Learning, Yaobang Gong

Electronic Theses and Dissertations, 2020-2023

As one of the most important Active Traffic Management strategies, Adaptive Traffic Signal Control (ATSC) helps improve traffic operation of signalized arterials and urban roads by adjusting the signal timing to accommodate real-time traffic conditions. Recently, with the rapid development of artificial intelligence, many researchers have employed deep reinforcement learning (DRL) algorithms to develop ATSCs. However, most of them are not practice-ready. The reasons are two-fold: first, they are not developed based on real-world traffic dynamics and most of them require the complete information of the entire traffic system. Second, their impact on traffic safety is always a concern by …

Understanding The Socio-Infrastructure Systems During Disaster From Social Media Data, Kamol Chandra Roy

Electronic Theses and Dissertations, 2020-2023

Our socio-infrastructure systems are becoming more and more vulnerable due to the increased severity and frequency of extreme events every year. Effective disaster management can minimize the damaging impacts of a disaster to a large extent. The ubiquitous use of social media platforms in GPS enabled smartphones offers a unique opportunity to observe, model, and predict human behavior during a disaster. This dissertation explores the opportunity of using social media data and different modeling techniques towards understanding and managing disaster more dynamically. In this dissertation, we focus on four objectives. First, we develop a method to infer individual evacuation behaviors …

Econometric Frameworks For Multivariate Models: Application To Crash Frequency Analysis, Tanmoy Bhowmik

Electronic Theses and Dissertations, 2020-2023

Econometric crash frequency models are a major analytical tool employed for examining the critical factors influencing crash occurrence. However, there are several methodological challenges associated with existing models suggesting a continual need to develop advanced econometric framework to address these gaps. The current dissertation contributes towards addressing the methodological challenges in crash frequency analysis for analyzing multiple crash frequency variables for the same study unit by proposing advanced econometric approaches. The first part of the dissertation contributes to safety literature by conducting a comparison exercise between the two major streams of multivariate approaches - (1) simulation-based approach and (2) analytical …

The Relationship Between Roadway Homogeneity And Network Coverage For Network Screening, Riana Tanzen

Theses and Dissertations--Civil Engineering

In the context of transportation safety engineering, network screening is a method of identifying and prioritizing high-risk locations for potential safety investment. Since its release, the Highway Safety Manual (HSM) has facilitated the adoption of Safety Performance Functions (SPF) to predict the number of crashes for the network screening of any facility type. The predictive model becomes more reliable when developed from crash data with homogeneous roadway segments and this homogeneity can be attained by applying specific geometric attributes to the dataset. The caveat to this method is the requirement of adjustment factors (AFs) to adjust the predicted estimate for …

Fluvial Sediment Organic Matter Degradation Identified With Elemental And Isotopic Fate During Laboratory Incubation, Brenden Riddle

Theses and Dissertations--Civil Engineering

Fluvial sediment is well recognized as a critical factor in both carbon and nutrient budgets within stream systems. However, we find very few studies of reactivity and isotope enrichment for stream water from agricultural and urban streams and the class of substrate known as fluvial sediment organic matter. This study investigated the hypothesis that fluvial sediment is subject to degradation even though many previous studies have considered this class of substrate generally inert. Therefore we qualify that elemental and isotopic signatures of fluvial sediment organic matter should be considered potentially non-conservative when used in tracer studies. Methods applied to this …

Adaptive Tracking Controller For Real-Time Hybrid Simulation, Alejandro Palacio-Betancur

Theses and Dissertations--Civil Engineering

Real-time hybrid simulation (RTHS) is a versatile and cost-effective testing method for studying the performance of structures subjected to dynamic loading. RTHS decomposes a structure into partitioned physical and numerical sub-structures that are coupled together through actuation systems. The sub-structuring approach is particularly attractive for studying large-scale problems since it allows for setting up large-scale structures with thousands of degrees of freedom in numerical simulations while specific components can be studied experimentally.The actuator dynamics generate an inevitable time delay in the overall system that affects the accuracy and stability of the simulation. Therefore, developing robust tracking control methodologies are necessary …

Probabilistic Approach To Water, Sediment, And Nutrient Connectivity For Advancing Watershed Modelling, David Tyler Mahoney

Theses and Dissertations--Civil Engineering

The goal of this dissertation is to represent the spatial and temporal domains of water, sediment, and nutrient flux and pathways within fluvial and watershed settings. To complete this goal, we integrate connectivity theory into watershed model structures to simulate water, sediment, and nutrient movement at the fundamental unit they occur. Fluvial-based sediment and nutrient flux is an important driver of global sediment and nutrient budgets, and the quantification of which serves as an ongoing challenge to limnologists, engineers, and watershed managers. Watershed models have been richly developed over the past century, but are currently restrained by problems related to …

A Modeling Approach To Understanding Glyphosate Transport In The Belize River Watershed, Barbara Anmei Astmann

Theses and Dissertations--Civil Engineering

Glyphosate is the most widely used herbicide worldwide and is often transported from application areas to surface water when solubilized in runoff or sorbed to eroded sediment. There is evidence that suggests both glyphosate and its main metabolite aminomethylphosphonic acid (AMPA) may pose a risk to human health, as well as cause adverse effects in the environment. However, consistent monitoring data is still limited, especially in developing countries. Belize is a developing nation with agriculture being a major sector of its economy and is heavily reliant on glyphosate. The widespread use of glyphosate in Belize may be resulting in glyphosate …