Engineering Commons^™

Mathematical Modeling: Finite Element Analysis And Computations Arising In Fluid Dynamics And Biological Applications, Jorge Reyes

UNLV Theses, Dissertations, Professional Papers, and Capstones

It is often the case when attempting to capture real word phenomena that the resulting mathematical model is too difficult and even not feasible to be solved analytically. As a result, a computational approach is required and there exists many different methods to numerically solve models described by systems of partial differential equations. The Finite Element Method is one of them and it was pursued herein.This dissertation focuses on the finite element analysis and corresponding numerical computations of several different models. The first part consists of a study on two different fluid flow models: the main governing model of fluid …

A One-Dimensional Analysis Of A Microbial Fuel Cell For Efficient Acetate Removal And Power Density Output, David Rouhani

UNLV Theses, Dissertations, Professional Papers, and Capstones

Microbial fuel cells (MFCs) are electrochemical devices that utilize microorganisms to convert organic matter into electrical energy. MFCs have been discussed to have potential application for sustainable wastewater treatment due to their ability to generate electricity while simultaneously treating contaminated water. To optimize MFC performance, numerical models can be used to understand the complex electrochemical and biological processes occurring in the system. In this study, a numerical model was developed to simulate the performance of MFCs under varying operating conditions and to investigate the performance of a MFC for treating wastewater fuel. More specifically, the MFC was modeled to oxidize …

Development Of An Automated Gpib System For Characterization Of Sige Avalanche Photodiodes, David A. Santiago

UNLV Theses, Dissertations, Professional Papers, and Capstones

Photon counting is a technique in many modern technologies such as medical imaging and LiDAR systems. Photon counting is needed in many aspects of the development process for these technologies from photodetector characterization to operation of the finished product. This thesis will serve to solve the challenge of quantifying photodetector performance using automating test equipment with known software packages such as MATLAB to be able tocharacterize photodetectors in an efficient manner. A custom MATLAB program has been developed to interface with various instrumentation using a General-Purpose Interface Bus (GPIB) and a Prologix GPIB-USB controller that will be able to send …

Simulating Condensation In The Theory Of Classical Nucleation, David Vallet

UNLV Theses, Dissertations, Professional Papers, and Capstones

The scope of this thesis is to numerically investigate condensation that occurs in transonic and supersonic flows. Condensation shocks are a phenomenon that occurs within converging-diverging nozzles. There are many applications forconverging-diverging nozzles, such as thermovapour compressors (TVC), which are largely used for desalination. As water resources become more precious within the western United States there is a need to develop cost effective solutions for cleaning water. Steam generator power stations are another application where enhanced simulations and accuracy of design could improve efficiency and save on carbon emissions. Traditionally, numerical designs of transonic flows have been conducted with either …

An Investigation Of Soft Electrohydraulic Actuators: Theory, Characterization, And Conceptual Applications, Alexandrea Washington

UNLV Theses, Dissertations, Professional Papers, and Capstones

Electroactive polymer (EAP) materials are a novel soft electromechanical device that exploits the inherent electrical and mechanical advantages of flexible polymer materials. Within this groundbreaking field there are various actuator and sensor devices that have been developed for a variety of applications, from medical devices to artificial biological systems. This research focuses on electrohydraulic actuators, which are comprised of a flexible conductive medium, a dielectric fluid, and a compliant film material to encapsulate the dielectric fluid. This specific study centers around the electrohydraulic EAP actuator known as the Hydraulically Amplified Self-Healing Electrostatic (HASEL) actuator, first introduced by the Keplinger group …

Analysis And Application Of Finite Element And High-Order Finite Difference Methods For Maxwell’S Equations In Complex Media, Li Zhu

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Perfectly Matched Layer (PML) technique is an effective tool introduced by B´erenger [13] to reduce the unbounded wave propagation problem to a bounded domain problem. This dissertation focuses on two different PML models and their applications to wave propagation problems with Maxwell’s equation in complex media. We investigate these models using two popular numerical methods: the Finite Difference Method (FDM) in Chapters 2 and 3, and the Finite Element Method (FEM) in Chapters 4 and 5.In Chapter 2, we focus on analyzing the stability of a PML developed by B’ecache et al. [10] for simulating wave propagation in the …

Non-Destructive Means Of Predicting Masonry Prism Strength Using Ultrasonic Pulse Velocity (Upv), Connor J. Barlow

UNLV Theses, Dissertations, Professional Papers, and Capstones

Current ASTM standards call for grouted masonry prisms to be tested for compressive strength at 28-days to ensure compliance with the structural design. In the event of failing tests, the subject samples may require redesign or reconstruction which can pose problems due to ongoing development around and including the prisms between the time of placement and obtaining test results. The purpose of this research is to determine if the use of ultrasonic pulse velocity (UPV) testing can be utilized to determine a correlation between prism composite strength of the masonry prism with ultrasound readings as to provide preliminary means of …

Field Application Of A High-Power Density Electromagnetic Energy Harvester To Power Wireless Sensors In Transportation Infrastructures, Anil Agrawal, Mohsen Amjadian, Wai Yan Tun, Hani Nassif, Hongfan Wang

Civil Engineering Faculty Publications

Finding an efficient source of energy has always been a big challenge for humans on Earth. Fossil fuels, such as coal and oil, have traditionally been considered as major sources of energy. These energy sources are not only nonrenewable but are also harmful to our health and environment. A large portion of this energy is consumed by vehicles moving daily in big cities, causing significant pollution of the environment. However, the motion of vehicles through the transportation infrastructures can also be a significant source of kinetic energy, which can be harvested to power transportation system components, such as sensors, street …

Reducing Infiltration And Inflow In Small Collection Systems: Environmental, Economic, And Other Impacts, Andrew Hansen

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

Wastewater treatment facilities (WWTFs) and the collection systems (CSs) which feed them provide essential services to society by collecting sewage (aka wastewater), biologically treating it, and minimizing risks to human health as well as the impact of waste on the environment. However, as collection systems age, increasing infiltration and inflow (I/I) from groundwater and stormwater can negatively affect the system. I/I is often mitigated to reduce flow and eliminate other negative impacts to the system.

Ten total case studies, seven mechanical water resource recovery facilities (WRRFs) and three lagoon facilities, were examined for the environmental, economic, and other impacts/benefits from …

Sustainable Revitalization Of Asphalt Pavements: An In-Depth Analysis Of Enhancing The Performance Of Asphalt Binder Through The Application Of Rheological And Molecular Dynamics Simulation Techniques, Muhammad Ahmad

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

Vegetable-based oils such as corn and soybean oil have triglycerides and fatty acids that allow them to be considered sustainable and effective recycling agents (RAs) for aged asphalt binder. However, there are concerns about their effect on the recycled asphalt binder's long-term performance, moisture damage resistance, and self-healing characteristics restoration. In this study, crude corn oil (CO) and crude soybean oil (SO) were used as RAs to restore the performance of a reclaimed asphalt binder (RAB) extracted from reclaimed asphalt pavement. The binder extracted from RAB was modified with a neat binder PG64-28 and RAs to restore the high-end performance …

Assessing The Performance Of High-Rap Mixtures Incorporating Crude Vegetable Oils And An Antioxidant From Mechanical, Environmental, And Economic Perspectives, Nitish R. Bastola

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

Utilization of mixtures with high amounts of reclaimed asphalt pavement (RAP) in the pavement industry is limited because of the adverse effects of aged materials in recycled asphalt materials. To date, numerous approaches have been used to reduce the adversity of RAP in mixtures. One such approach is the use of recycling agents (RAs) from various sources, such as petroleum and bio-oil. However, the current need is to maximize the use of RAP by adopting a sustainable source of RAs. Therefore, this study uses two RAs based on vegetable oils (crude soybean oil and crude corn oil) with high-RAP mixtures …

Design Of A Miniature Robotic Surgery Technology Demonstration Payload For Orbital Spaceflight, Rachael A. Wagner

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

This thesis describes the design of a technology demonstration payload that will test robotic surgery while aboard a 2024 expedition of the International Space Station (ISS). The payload utilizes a new miniature surgical robot to complete simulated surgical tasks on orbit, both autonomously and while remotely controlled by an Earth-based user. The experiment investigates the effects of microgravity and latency on robotic surgery, with the following goals:

1. Demonstrate the use of a miniature robotic surgical system in microgravity through performing simulated surgical tasks.

2. Quantify the effects of microgravity on robotic surgical techniques including forces, torques, and kinematic accuracy. …

Blood Flow Regulates Atherosclerosis Progression And Regression, Morgan A. Schake

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

Atherosclerosis is the most prevalent pathology of cardiovascular disease with no known cure. Despite the many systemic risk factors for atherosclerosis, plaques do not form randomly in the vasculature. Instead, they form around bifurcations and the inner curvature of highly curving arterial segments that contain so-called disturbed blood flow that is low in magnitude and multidirectional over the cardiac cycle. Conversely, straight, non-bifurcated arterial segments that contain moderate-to-high and unidirectional (i.e., normal) blood flow are protected from plaque development. Thus, blood flow is a key regulator of atherosclerosis that may be able to be leveraged to develop new therapeutics. Towards …

Editorial: Innovative Shared Transportation, Marco Nie, Hai Wang, Wai Yuen Szeto

Research Collection School Of Computing and Information Systems

Recent technological developments—mobile computing, autonomous driving, alternative fuel vehicles, and blockchain, to name a few—have enabled numerous innovations in mobility, transportation, and logistics services. They offer unprecedented opportunities to transform conventional transportation systems, for both personal travel and freight logistics, with novel solutions. Of these solutions, those built on the emerging concept of shared economy, such as Uber, Didi, and Cargostream, have received much attention recently. The rapidly expanding scope of shared transportation services now includes ride-sourcing, ridesharing, car sharing, hitch service, flexible paratransit, shared freight delivery, shared logistics, bike sharing, shared last-mile service, parking space sharing, and so on.

Polymeric Biomaterials Approaches For Engineering The In Vitro Cellular Microenvironment For Mscs, Mahsa Letter-Mahsa Haseli

Graduate Theses and Dissertations

Cell therapy is a technology that relies on replacing diseased or dysfunctional cells with healthy functioning ones. One of the cells used for such advanced therapies are stem cells, owing to their ability to differentiate into specific cells required for repairing damaged or defective tissues or cells. The majority of cell-based products are intended to transiently persist in the patient, secreting factors which then allow the patient’s body to heal; in these products, the cells are subsequently eliminated from the body. Furthermore, unique manufacturing platforms, in addition to novel commercialization strategies, will be required to create a successful, sustainable cell …

Analysis Of An Isolated Bidirectional Ćuk Converter, Yeny Hau Chen

Graduate Theses and Dissertations

The objective of this thesis is to perform an analysis of the isolated bidirectional Ćuk dc-dc converter topology and demonstrate the advantages and operation of this configuration through simulations using MATLAB/SimulinkTM and measurements collected from a 1.5-kW prototype tested at the Engineering Research Center (ENRC) laboratory of the University of Arkansas. The idea of integrating an active-clamp snubber circuit on each side of the converter, proposed by Dr. Sudip Mazumder from the University of Illinois, Chicago, limits the additional voltage stresses on the components due to the energy from the transformer’s leakage inductance. This is studied in this thesis to …

Producing Analytical Models Of The Sport Spacecraft For Science Data Processing, Jason L. Powell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Scintillation Prediction Observation Research Task (SPORT) is a joint United States of America and Brazil 6U CubeSat mission. The SPORT mission is to understand how the Earth’s ionosphere evolves during day and night transitions. Space Weather Probes, a suite of instruments developed by Utah State University, monitors the ionosphere by observing currents and voltages around the SPORT spacecraft body. This thesis presents the data collected by Space Weather Probes and how it is used to measure the ionosphere. Modeling techniques are also presented to demonstrate how the Space Weather Probes instrument is expected to respond to the ionosphere.

Preferences Toward Augmented Reality Technologies For Pedestrian Navigation, Victoria Alejandra Diaz Mejia

Theses and Dissertations

This research investigates the demand for pedestrian navigation supported by augmented reality (AR) via headset and mobile technologies by evaluating factors specific to each technology and the decision makers. Recent advances in digital engineering systems, e.g., digital twins and smart cities, are enabling new services like AR-supported wayfinding for pedestrians. Still, it is unknown whether American pedestrians would use AR, the type devices and feature that add value to their navigation, the demographic profiles more inclined to AR wayfinding, and the sensitivity of such demand to software and hardware cost. As the first investigation addressing the demand for AR pedestrian …

Cfis’ Safety Behaviors At Flight Training Schools: Understanding The Effects Of Personality Traits, Self-Efficacy, Risk Perception, And Safety Climate, Vivek Sharma

Theses and Dissertations

The purpose of the current study was to investigate the relationship between personality traits, affective domain variables, safety climate, and safety behaviors of certified flight instructors (CFIs). Personality traits consisted of the five dimensions of the Big Five personality model, including Extraversion, Neuroticism, Agreeableness, Openness, and Conscientiousness. Affective domain variables included self-efficacy and risk perception. The study used an explanatory correlational design to determine the relationship between the targeted factors and safety behaviors. The dependent variable was CFIs’ safety behaviors. The sample consisted of 134 CFIs who completed all of the study’s protocols. Participants were obtained from a professional flight …

Improving The Learning Efficiency Of Adaptive Optimal Control In Information-Limited Environments, Omar Ghassan Qasem

Theses and Dissertations

This work investigates the adaptive optimal control problems for continuous-time linear and nonlinear systems. A novel adaptive dynamic programming method, namely hybrid iteration (HI) is presented. Different from the existing adaptive dynamic programming methods, i.e., policy iteration (PI) and value iteration (VI), the HI does not require an initial admissible control policy compared to the PI. On the other hand, the HI converges to the optimal control policy in much less learning iterations and CPU time compared to the VI due to the ensured quadratic rate of convergence of the HI method, which is much faster than the sub-linear convergence …

Effects Of Process Parameters On The Dimensional Accuracy Of Fused Deposition Modeled Parts, Ethan Eugene Bair

Theses and Dissertations

Fused deposition modelling (FDM) is one of the most common additive manufacturing techniques used with applications ranging from rapid prototyping at a professional scale to simple part creation at a hobbyist scale. FDM printing has very little in terms of information based on how accurate printed parts can be. This issue, which is common amongst many different types of additive manufacturing techniques, is something that has not been studied in FDM printed parts in high volumes. Research based on the effects of process parameters on mechanical properties has been conducted in high proportions. This study focused on FDM machines using …

A Reduced Order Model For Estimation Of Fractional Flow Reserve (Ffr) In Coronary Artery Disease: Assessing The Impact Of Side Branches, Arber Vila

Theses and Dissertations

Coronary Artery Disease (CAD) affects millions of people worldwide and remains a leading cause of morbidity and mortality. To effectively plan treatment and risk stratification, assessing CAD severity is of paramount importance. Fractional flow reserve (FFR) is a critical clinical parameter used to evaluate CAD severity, measured by the ratio of mean distal coronary pressure to mean aortic pressure during hyperemic conditions. Although non-invasive FFR estimation methods have gained popularity, computational fluid dynamics (CFD) is impractical for routine clinical use due to the time and resources required. To address this issue, a reduced order model is proposed that accurately captures …

Estimating Seasonal Crop Water Consumption In Irrigated Lands Using Soil Moisture And Reference Evapotranspiration, Oliver Henry Hargreaves

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The increase in population and the megadrought that the American west has been experiencing for the past two decades and for the foreseeable future are the cause of great stress on the region’s water resources. In an effort to mitigate the worst effects of water shortages many public and private agencies have been pursuing ways to reduce water use while maintaining the current status quo of living standards, industrial productivity, and agricultural yield. This project aims to study water use in irrigated lands dedicated to agriculture with the objective of quantifying crop water use, often referred to as evapotranspiration (ET), …

Comparing 1d, 2d, And 3d Hydraulic Models In Urban Flooding Applications, Taylor Kesler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Floods have been a hazard to people since people first started building near rivers. Predicting floods can be very beneficial to save lives and property. Computers have made it possible to solve fluid dynamics equations in a fast and efficient manner. Computer programs have been designed to solve these equations and create digital models of floods.

This study compares three different methods of computer modeling and explores their advantages and disadvantages. One-dimensional models solve fluid equations by setting up a series of cross sections. Two-dimensional models use a grid-like mesh to solve fluid equations from one cell to the next. …

Improved Sustainability And Efficiency Of Partial Depth Concrete Bridge Deck Repair, Israi I. H. Abu Shanab

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Recently, significant advances have been made in the development of rapid setting cementitious materials for partial depth bridge deck repair. The rapid set times of these materials allow for traffic to be re-opened onto the bridge deck in several hours versus days once the material has been placed. While this is a substantial improvement in reducing the traffic closure time, a large amount of time is still spent on the removal of damaged and deteriorated bridge deck and in preparing the concrete cutouts for placement of the rapid set material. Partial deck removal is a much more delicate process than …

Low-Erosion Nozzle Materials For Long-Duration Hybrid Rocket Burns, Russell S. Babb

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Hybrid rocket systems, which employ a solid fuel grain and a liquid oxidizer, are a low-cost and environmentally friendly alternative to traditional rocket systems. However, hybrid rockets suffer from an increased nozzle throat erosion rate, which impacts motor performance and reliability. To address this issue several materials and low-erosion nozzle configurations were tested. The results of the testing campaign produced a nozzle that reduce the throat erosion rate five-fold.

Groundwater-Surface Water Interaction To Increase Groundwater Availability, Saeid Masoudiashtiani

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study develops procedures for using surface water to increase groundwater availability and sustainable yield, and for evaluating impacts on surface water. Increasing sustainable groundwater yield requires reducing the gap between the volumes of discharge from versus recharge to an aquifer. The study presents procedure for water user(s) to help increase groundwater availability. Toward that end, this study simulates and evaluates: a) aquifer storage and recovery (ASR) of water diverted from Red Butte Creek in Salt Lake Valley, Utah for subsequent turf irrigation; b) ASR injection of residential runoff from daily rainfall for subsequent extraction to irrigate turf; and c) …

Probabilistic Verification For Modular Network-On-Chip Systems, Jonah W. Boe

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Modeling physical systems with formal analysis tools can help in the design of more fault-proof systems, by helping to determine if unpredictable or unwanted behavior may occur. Probabilistic verification further advances such processes, by providing quantitative information about the system. More complex systems can especially benefit from formal modeling and verification, as testing the physical system in every possible condition manually, can be extremely complex, and often impossible.

There is a growing interest in the application of Network-on-Chip (NoC) systems. NoCs can help simplify communication between the subsystems of many technologies, including the ever more complex multicore processors being produced. …

Aerodynamic Implications Of A Bio‐Inspired Rotating Empennage Design For Control Of A Fighter Aircraft, Christian R. Bolander

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This dissertation presents an analysis of the aerodynamics for an aircraft using a novel, bio-inspired control system. The control system is a rotating tail, that is inspired by the way in which birds use their tail to control their flight. An aerodynamic model for a baseline aircraft and a bio-inspired variant are created by referencing well-known relationships for the aerodynamics of flight, which are then used to analyze the available flight envelope at which each aircraft can reach two different equilibrium states. An analysis of the total aerodynamic control authority of each aircraft is also included along with a preliminary …

The Active Cryocubesat Technology: Active Thermal Control For Small Satellites, Lucas S. Anderson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Modern CubeSats and Small Satellites have advanced in capability to tackle science and technology missions that would usually be reserved for more traditional, large satellites. However, this rapid growth in capability is only possible through the fast-to-production, low-cost, and advanced technology approach used by modern small satellite engineers. Advanced technologies in power generation, energy storage, and high-power density electronics have naturally led to a thermal bottleneck, where CubeSats and Small Satellites can generate more power than they can easily reject. The Active CryoCubeSat (ACCS) is an advanced active thermal control technology (ATC) for Small Satellites and CubeSats, which hopes to …