Engineering Commons^™

Effectiveness Of Softening Agents For Enhancing Properties Of Asphalt Mixes With High Rap Contents, Zahid Hossain, Ashraf Elsayed, Sumon Roy

Publications

A high percentage of reclaimed asphalt pavement (RAP) in new asphalt concrete can lead to developing premature failure of asphalt pavements due to fatigue or low-temperature cracking. The use of softening agents in asphalt binders can resolve these problems. The aim of this study is to evaluate the effectiveness of softening agents for enhancing the properties of asphalt mixes with high RAP contents. Two waste products, namely, waste cooking oil (WCO), and engine bottom oil (EBO) along with a commercially produced rejuvenator were investigated in this study. The following three types of Performance Grade (PG) binders, each collected from two …

Feasibility Assessment Of Warm Mix Asphalt In Arkansas, Zahid Hossain, Ashraf Elsayed, Mohammad Najmush Sakib Oyan

Publications

The future of Warm Mix Asphalt (WMA) technologies is promising in the U.S. However, the Arkansas Department of Transportation (ARDOT) does not have any specific guidelines to implement them in the field. This research aims to provide necessary baseline data for WMA as a proof of concept. In this study, three ARDOT approved Performance Grade (PG) binders namely PG 64-22, PG 70-22, and PG 76-22 were investigated. Each of these binders was obtained from two different sources. They were modified by varying doses of four selected additives: Sasobit®, Advera®, Evotherm®, and Rediset®. Additionally, four different types of aggregates (sandstone, limestone, …

Development Of Cost-Effective High-Modulus Asphalt Concrete (Hmac) Mixtures Using Crumb Rubber And Local Construction Materials In Louisiana, Momen R. Mousa, Marwa Hassan, Ibrahim A.I.E Elnaml

Publications

One of the emerging solutions to enhance the durability of asphalt pavements is the use of a French asphalt mix known as “High-Modulus Asphalt Concrete (HMAC).” This mix uses a hard asphalt binder, high binder content (about 6%), and low air voids content as compared to Superpave mixtures. The key objective of this study was to develop a cost-effective HMAC mixture using crumb rubber and local materials in Louisiana. To achieve this objective, four HMAC mixtures were prepared using two asphalt binders (PG 82-22 and PG 76-22 plus 10% crumb rubber) and two Reclaimed Asphalt Pavement (RAP) contents (20% and …

Evaluation Of Alternative Sources Of Supplementary Cementitious Materials (Scms) For Concrete Materials In Transportation Infrastructure, Gabriel A. Arce, Miladin Radovic, Zahid Hossain, Marwa Hassan, Sujata Subedi

Publications

Fly ash is the most utilized supplementary cementitious material (SCM) in the US. Nonetheless, rapid decline in coal-fired power generation threatens its supply. The objective of this study was to evaluate alternative SCMs for concrete transportation infrastructure in Region 6. SCMs investigated included reclaimed fly ash (RFA), reclaimed ground bottom ash (GBA), metakaolin (MK), and conventional Class F fly ash (FA) as a reference. SCMs were characterized and the fresh and hardened properties of concrete incorporating different dosages (i.e., 10, 20, and 30% cement replacement by mass) of the individual SCMs (i.e., binary systems) and blended SCM systems of RFA-MK …

Resilient 3d-Printed Infrastructure With Engineered Cementitious Composites (Ecc), Maryam Hojati

Publications

Conventional construction of reinforced concrete structures is slow, labor-intensive, and expensive. 3D printing holds great potential to assist engineers and architects in constructing fast and economical yet complex representational infrastructures. One of the most significant barriers to the broader adoption of concrete 3D printing in civil infrastructure is the difficulty of providing printed structural components with reinforcement to achieve sound structural performance under different loading conditions. Hence, it is essential to design concrete that can be utilized as a rebar-free material by considering strength and ductility. Recently, the development of Engineered Cementitious Composites (ECC) has neared the possibility to achieve …

Evaluation Of Sustainable And Environmentally Friendly Stabilization Of Cohesionless Sandy Soil For Transportation Infrastructure, Miladin Radovic, Anand Puppala, Surya Sarat Chandra Congress, Jungyeon Jang, Oscar Huang

Publications

Ordinary Portland cement (OPC) is generally used to stabilize cohesionless sandy soils that are often found in coastal areas. Due to its high carbon footprint, many studies are being conducted to identify a suitable green alternative for stabilizing cohesionless soils. Previous studies have shown that partially replacing OPC with waste materials such as nano-silica and coal waste reduces the overall carbon footprint without significantly impacting the performance. Geopolymer (GP) received a lot of attention in the past few decades owing to its similar properties to that of OPC yet with a lower carbon footprint. This study investigated the feasibility of …

An Automated System For Inspecting Rock Faces And Detecting Potential Rock Falls Using Machine Learning, John Stormont, Fernando Moreu, Amir Bagherieh, Roya Nasimi, Solomon Atcitty

Publications

Rockfall is a hazard in mountainous areas threatening infrastructure and human lives. Rockfall hazards are often mitigated by manual inspections using pry bars. The inspector must access the rock face, hit the rock surface, detect, and remove the loose rocks. This method is very labor demanding, unsafe, and challenging. This research presents a method that automatize the inspection of rock blocks that are prone to rockfall events. A robot is developed to replace the manual hammer tap process and collect the sound data remotely; subsequently, the sound signal is used to identify different types of the discontinuity in rocks in …

Resource Guide For State Dot’S Maintenance Equipment Fleet Management Decisions, Yongwei Shan, Samir Ahmed, Lei Qiao

Publications

This research created a guide for state Departments of Transportation fleet management on utilizing equipment fleet management system data to make informed fleet management decisions. The research team took the historical equipment fleet data from the Oklahoma Department of Transportation and developed workflows, algorithms, and examples to demonstrate the use of historical equipment data for equipment decisions. Specifically, the research team demonstrated 1) the use of life cycle analysis and dynamic programming models for equipment replacement decisions; 2) developed algorithms to calculate equipment rental rates that can be used by the Department to forecast and allocate equipment operational budget among …

Preventing Struck-By Hazards: Defying Risk-Habituation Via Virtual Accident Simulation, Changbum Ahn

Publications

Repeated exposure to struck-by hazards in road work zones generates workers’ habituation to risks related to those hazards, a key contributor to accidents in road work zones. Thus, analyzing the development of risk habituation and providing proper intervention are crucial to preventing accidents in road work zones. In this context, this study employs a virtual reality (VR) environment as a behavioral intervention tool to investigate its effect on mitigating a decline in workers’ vigilance with habituation to hazards in workplaces. A virtual environment that simulates a road maintenance task was developed and used to repeatedly expose subjects to struck-by hazards …

Bridge Cracks Monitoring: Detection, Measurement, And Comparison Using Augmented Reality, Fernando Moreu, Kaveh Malek

Publications

Crack occurrence and propagation are among critical factors that affect the performance and lifespan of civil infrastructures such as bridges. Consequently, numerous crack detection and measurement methods have been proposed and developed in the recent decades in the areas of Structural Health Monitoring and non-destructive testing. Many novel technologies have emerged with the potential to overcome the limitations of the presented techniques of crack detection and characterization. Crack detection and characterization method used in this research lies in supplementing human visual inspection capabilities in a systematic manner through an appropriate level of automation. The Augmented Reality (AR) tool developed in …

Maintenance And Restriping Strategies For Pavement Markings On Asphalt Pavements In Louisiana, Momen R. Mousa, Marwa Hassan

Publications

In Louisiana, most districts restripe their roadways using waterborne paints every other year; this strategy is questionable in terms of efficiency and economy. Meanwhile, previous studies showed substantial variability in the paint service life throughout the United States ranging between 0.25 and 6.2 years. Shortcomings in modeling the retroreflectivity of waterborne paints appear to significantly contribute to these variations as several studies predicted these values using degradation curves with a coefficient of determination (R2) as low as 0.1. Therefore, the objective of this study was to (i) develop new cost-effective restriping strategies using 4-inch (15-mil thickness) and 6-inch (25-mil thickness) …

Determination Of The Optimal Parameters For Self-Healing Efficiency Of Encapsulated Bacteria In Concrete Simulated Subtropical Climate, Momen R. Mousa, Marwa Hassan, Gabriel Andres Arce Amador, Ricardo Hungria, Andrea Gavilanes, Omar Kamal

Publications

Concrete is a remarkable construction material. However, its low tensile strength makes it prone to cracking, which negatively affects its durability. To address this issue, bacterial concrete has been implemented as a self-healing alternative due to its capability to seal microcracks through microbial-induced calcium carbonate precipitation (MICCP). In this study, a bacterial strain (i.e, Bacillus Pseudiformus) was encapsulated through three different methods: encapsulation through hydrogel beads, vacuum impregnation on lightweight aggregates, and attachment to cellulose nanocrystals. Furthermore, three precursor types were used, magnesium acetate, calcium lactate, and sodium lactate were implemented. Compressive strength tests and flexural strength tests were performed …

Development Of A Multi-Level Dynamic Model To Measure The Resilience Level Of Transportation Infrastructure Networks, Sharareh Kermanshachi, Jianling Li, Thahomina Jahan Nipa

Publications

The recent increase in disasters is making the largest critical infrastructure system namely the transportation infrastructure system susceptible to unexpected damage. Discontinuation of services provided by transportation infrastructures will create significant societal, economic, and collateral damages. Therefore, this study aims to identify dimensions to measure the resilience of the transportation infrastructures. This study also aims to develop a model to measure the resilience of the transportation infrastructures resilience. To fulfill the aims of this study, a questionnaire was developed which was supported by a comprehensive literature review. 92 valid responses were received and analyzed qualitatively and quantitatively. Statistically significant variables …

The Coalescence Of Incipient Soot Clusters, Akaash Sharma, Khaled Mosharraf Mosharraf Mukut, Somesh Roy, Eirini Goudeli

Mechanical Engineering Faculty Research and Publications

Reactive molecular dynamics (MD) simulations are employed to investigate the coalescence of incipient soot clusters. Initially, one thousand acetylene molecules collide and react with each other, allowing bond breakage and new bond formation upon collision, leading to various species (e.g., linear hydrocarbons, branched polyaromatic hydrocarbons) up to the formation of nascent soot clusters with diameter of up to 3.5 nm. The structure and composition of the formed soot clusters are quantified by the packing density and carbon-to-hydrogen (C/H) ratio, respectively, during nucleation and up to the formation of large nascent soot nanoparticles. Then, the nucleated incipient soot clusters are isolated …

Development Of A Low-Cost, Photovoltaic-Powered, Automated Water Recovery System, David E. Daley

Master's Theses

An existing water filtration system at the Channel Islands Marine & Wildlife Institute (CIMWI) wastes approximately 25 gallons of water per day rinsing out solid waste under light load. To reduce CIMWI’s water and energy consumption, an automated system was designed and built to recover the rinse water and return it to the existing filtration loop. Models for fluid system requirements, basic energy needs, and photo- voltaic energy generation were created to aid in component selection. Basic sensors and electronics were programmed in Python for use with a Raspberry Pi single board computer to collect and process water recovery data …

Integral Boundary Layer Methods In Python, Malachi Joseph Edland

Master's Theses

This thesis presents a modern approach to two Integral Boundary Layer methods implemented in the Python programming language. This work is based on two 2D boundary layer methods: Thwaites' method for laminar boundary layer flows and Head's method for turbulent boundary layer flows. Several novel enhancements improve the quality and usability of the results. These improvements include: a common ordinary differential equation (ODE) integration framework that generalizes computational implementations of Integral Boundary Layer methods; the use of a dense output Runge-Kutta ODE solver that allows for querying of simulation results at any point with accuracy to the same order as …

High Voltage Dc-Dc Converter Design For Submarine Application, Oscar Ambriz

Master's Theses

In this work a proof of concept for a step-down DC-DC converter used in a high voltage submarine application is presented. The purpose of the converter is to step down a 5000V-6000V input to a 24V output which can serve as an input to a submarine sensor. The completed system consists of two stages where the first stage is an unregulated switched capacitor converter to step down the initial input to a voltage range more appropriate for the selected second stage. The second stage is a regulated flyback converter topology which regulates the final output to the desired 24V. Performance …

Design And Analysis Of A Single-Stage Inverter Using Parallel Dc-Dc Converters For Solar Cell Application, Gabriel Leonides

Master's Theses

This thesis introduces the design and analysis of a single-stage inverter. A circuit was designed and simulated as a proof of concept to investigate the possibility of using boost and buck-boost converters to provide an AC output. The proposed circuit utilizes non-synchronous boost and buck-boost converters due to their simplicity in control signals as opposed to synchronous converters. The application of the proposed inverter is for use with individual solar cells. The aim of the inverter for a single cell is to improve the efficiency of a solar panel, whose performance is limited to the performance of the least efficient …

Knn Based Piezo-Triboelectric Lead-Free Hybrid Energy Films, Abu Masa Abdullah, Muhtasim Ul Karim Sadaf, Farzana Tasnim, Horacio Vasquez, Karen Lozano, M. Jasim Uddin

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

In recent times, the triboelectric and piezoelectric effects have garnered significant attention towards developing advanced material composites for energy harvesting and sensory applications. In this work, potassium sodium niobate (KNN) based energy films (EF) have been developed to utilize mechanical energy while simultaneously taking advantage of triboelectric and piezoelectric mechanisms. The KNN particles were synthesized using a wet ball milling technique and then incorporated into a polyvinylidene difluoride (PVDF) matrix together with addition of multi wall carbon nanotubes (MWCNT). The film was used to develop a piezoelectric nanogenerator (PENG) fitted with copper electrodes. The piezoelectric output of the film was …

Two-Dimensional Modeling Of Nonlinear Dynamics Of Forcespinning Jet Formation, Dumitru I. Caruntu, Simon Padron, Karen Lozano

Mechanical Engineering Faculty Publications

Forcespinning is a novel method that makes use of centrifugal forces to produce nanofibers rapidly and at high yields. To improve and enhance the forcespinning production method, a 2D computational forcespinning inviscid fluid dynamics model is developed. Two models, namely, time-independent and time-dependent, are obtained in order to investigate the effects of various parameters on fiber forcespinning formation (trajectory, jet diameter, tangential velocity). The fluid dynamics equations are solved using the method of multiple scales along with the finite difference method and including slender-jet theory assumptions. It is important to produce jets with small diameters in the micro- and nanorange. …

Effect Of Additional Weight On Stability Of Human Squat Exercise, Jose De Jesus Galarza Lozano

Theses and Dissertations

The main focus of the study is to analyze the stability of the squat exercise. The squat is a common exercise that persons do for exercise. The study analyze the time series of the normal component of the ground reaction forces and each coordinate of the center of pressure. Theses time series are used to estimate the Lyapunov Exponents using Rosenstein method. MATLAB from Mathworks is used to calculate the graphs and program the methods. We compare this result with the literature and previous experiments. This work gives more information relating the safety of the squat exercise when …

Exploration Of Corridor-Based Tolling Strategies For Virginia’S Express Toll Lanes, Shanjiang Zhu, Mecit Cetin, Hong Yang, Olcay Sahin, Atabak Mardan

Civil & Environmental Engineering Faculty Publications

Virginia has invested significant resources in the development of express toll lanes (ETLs), which adjust toll rates dynamically based on the level of toll lane usage. A tool is needed to investigate the potential impact of the I-66 Outside-the-Beltway (OTB) ETLs on regional traffic patterns. This study developed a microscopic traffic simulation model in TransModeler to evaluate a set of corridor-based tolling strategies for the I-66 ETLs in NOVA. This model also considered the changes in vehicle occupancy, mode split, and departure time among travelers because of tolls based on locally collected data. An interactive map-based analyzer based on the …

Rotten With Prediction, Serena Raquel Hicks

UNLV Theses, Dissertations, Professional Papers, and Capstones

This project focuses on the relationship between religion and technology as it is portrayed in Science Fiction (SF). This thesis explores the SF genre rhetorically by examining the 2002 movie Minority Report (MR), which signaled the importance of surveillance and the need to predict future crimes following 9/11. The events of 9/11 played a significant role in post 9/11 SF films, which reflect and critique our communal and cultural values. 9/11 created a new relationship between the U.S justice system, predictive technologies (PTs), and data gathering. Through the Bush Doctrine of “preemptive action,” the U.S government attempted to use Dataism, …

Design, Analysis And Experimental Evaluation Of 3d Printed Variable Stiffness Structures, Rossana R. Fernandes

Doctoral Dissertations and Master's Theses

The rapid progress of additive manufacturing (AM) introduces new opportunities but also new challenges for design and optimization to ensure manufacturability, testability and accurate representation/prediction of the models. The present dissertation builds a bridge between design, optimization, AM, testing and simulation of advanced optimized variable-stiffness structures. The first part offers an insight on the mechanical, viscoelastic and failure characteristics of AM continuous fiber composites. This understanding was used in the second part to investigate the feasibility of different topology and fiber-orientation optimization methods and the manufacturability of the resulting models. The study also assesses the effects of the manufacturing constraints …

Investigation On The Interaction Of An Impinging Jet With Cylinder Wakes, Karthik Krishna

Doctoral Dissertations and Master's Theses

Jet impingement cooling is a widely used cooling method due to the high heat transfer rates associated with it. Research for improving heat transfer rates for this cooling is still being carried out due to its broad application in various fields like gas turbine blade cooling, electronic component cooling, and paper drying. The unsteady jet oscillation effectively enhances the stagnation region and the time-averaged heat transfer rates. It is shown that a novel passive jet oscillation technique can be achieved using the vortices periodically shed from a cylinder placed upstream in a channel with an initial crossflow. Preliminary CFD results …

Probabilistic Seismic Vulnerability Assessment Of Freestanding Historic Monuments, Marie E. Wagner

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Seismic events can cause significant damage to structures, especially to freestanding structures which are not fixed to the ground and are free to rock independently. This thesis will study the response of freestanding statues and monuments to ground motions and develop probabilistic models for overturning, in order to assist in retrofitting and repair efforts. To do this, single and dual block system models were created with a variety of sizes, aspect ratios, and asymmetries, then subjected to several historic ground motions to determine whether they overturn using three-dimensional distinct element analysis as a result of rocking, sliding or twisting in …

Toward An Understanding Of Fundamental Mechanisms In Transitional And Turbulence Flow Control, Ethan A. Davis

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Turbulence is an emergent phenomenon found throughout nature and engineering, alike. It plays a vital role in the aquatic locomotion of organisms, scalar mixing, fluid transport, shipping and transportation, and even the flow of biological fluids in the human body. Therefore, it is of utmost importance in both a practical and engineering sense to better understand turbulence with the goal of better controlling it. This dissertation focuses broadly on better understanding the underlying mechanisms behind wall-bounded turbulent flows, with an emphasis on exploiting those mechanisms for turbulence flow control.

We developed a numerical simulation to study the effect of slip …

Thermomechanical Modeling In Laser Powder Bed Fusion Additive Manufacturing Using Graph Theory: Application To Prediction Of Recoater Crash, Md Humaun Kobir

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

This work pertains to the laser powder bed fusion (LPBF) additive manufacturing process. The objective of this thesis is to predict a frequently occurring type of thermal-induced process failure in LPBF called recoater crash. To ascertain the likelihood of a recoater crash before the part is printed, we develop and apply a computationally efficient thermomechanical modeling approach based on graph theory.

Despite its demonstrated ability to overcome the design and processing constraints of conventional subtractive and formative manufacturing, the production-level scaleup of LPBF is hindered by frequent build failures. For example, the part often deforms as it is being printed …

Development Of A Mash Tl-3 Compliant Parapet Mounted Fence, Luis Rodriguez Alvizo

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

When roadways pass over railway tracks, there is a risk that debris from the roadway or pedestrians may fall onto the tracks and interfere with railway operations. Because of this, state Departments of Transportation (DOTs) commonly install debris fences in conjunction with bridge rails over railway tracks. However, the safety performance of debris fence systems when impacted by an errant vehicle has not been demonstrated through full-scale crash testing. Thus, the objective of this research was to develop a new, parapet-mounted debris fence for the Iowa DOT according to safety performance guidelines included in the American Association of State Highway …

Multistage Stochastic Programming: Algorithms, Modelling And Applications, Murwan Siddig

All Dissertations

This dissertation comprises four di˙erent topics related to multistage stochastic program-ming (MSP) algorithms, modeling, and applications.

First, we extend the adaptive partition-based approach for solving two-stage stochastic programs with a fixed recourse matrix and a fixed cost vector to the MSP setting, where the stochastic process is assumed to be stage-wise independent. The proposed algorithms integrate the adaptive partition-based strategy with a popular approach for solving multistage stochastic programs, the stochastic dual dynamic programming (SDDP) algorithm, according to two main strategies. These two strategies are distinct from each other in the manner by which they refine the partitions during the …