Engineering Commons^™

Investigation Of Gaas Double Heterostructures For Photonic Heat Engines, Nathan Giannini-Hutchin

Optical Science and Engineering ETDs

The creation of a laser cooled semiconductor device has been a long sought achievement. GaAs-based devices have emerged as a promising candidate for the realization of this goal. Efforts to improve the efficiency of such devices have enabled the material to exhibit external quantum efficiencies (EQE, a measure of the probability that an excitation leads to the emission of a photon) of 99.5\%. Despite this impressive feat, a laser coolable device remains elusive.

To investigate the obstacles to such a device, the material characteristics of GaAs-based double heterostructures (DHS) are theoretically and experimentally examined. Through this study, a GaAs $\vert$ …

Optimization And Enhancement Of Co2 Sequestration In Industrial Wastes For Environmental Applications, Maisa El Gamal, Ameera F. Mohammad

All Works

This paper explores carbon capture and storage (CCS) through carbide lime waste (CLW), a by-product of acetylene production, under different conditions. This process is specifically designed to provide an onsite waste management solution for several industries that can easily be integrated into existing systems. In addition, the effect of the carbonation process on collected solids morphology and average particle size was studied. The structural and chemical characteristics of the carbonated carbide lime samples were investigated using X-ray diffraction, scanning electron microscopy, TGA analysis, and Raman spectroscopy. The effect of carbonation conditions on the total dissolved solids and change in pH …

Dynamic Surface Tension Of Surfactants Through Separation Of Diffusion And Dilation Effects, Brandon Ortiz

UNLV Theses, Dissertations, Professional Papers, and Capstones

Surfactants are biphilic monomers that adsorb to interfaces and have the ability to reduce interfacial tension. From this reduction in interfacial tension, surfactants are able to function as emulsifiers, detergents, and wetting agents among a variety of other things. Despite their ubiquity surfactants and surfactant behaviors, in particular those in highly dynamic environments, are not yet well characterized. In these environments, surfactants undergo significant distortions to droplet, bubble, and foam geometries which induce changes to the surface tension. This establishes a need to understand how surfactants respond to distortions of geometry through diffusion and dilational effects. To address this need, …

Towards The Electronic Response Of Carbon-Based Van Der Waals Heterostructures In A Diamond Anvil Cell, George Thomas Foskaris

UNLV Theses, Dissertations, Professional Papers, and Capstones

The nanoscale regime of materials has been at the forefront of research and interest in condensed matter physics for many years. In a merger of the fields of two-dimensional (2D) materials and high pressure physics, we present an investigation of the electronic response of carbon-based, van der Waals (vdW) heterostructures in a diamond anvil cell (DAC). Combining these fields presents us with the ability to study the characteristics of such systems both optically, and through electrical transport. Properties such as conductance, band structure, and layer number are considered. The samples in this study are assembled using exfoliation and stacking techniques …

Multi-Criteria Decision Matrix Method In The Risk Analysis Of Biodiesel Production Processes, Kaylee Alles

Department of Chemical and Biomolecular Engineering: Dissertations, Theses, and Student Research

Renewable fuel technologies aim to mitigate the non-renewability of fossil fuels, challenges with increased energy demand, and the climate impact of fossil fuel emissions. However, before investing in renewable technologies, there need to be decision strategies that assess and identify the best alternatives according to stakeholder priorities. There is also a concern about whether the technologies that are the “most sustainable” effectively meet the acceptable risk requirements of stakeholders. In response to this question, a risk-adapted multi-criteria decision model was developed and compared to a sustainability study that evaluated five renewable diesel technologies, including Green Diesel I, II, and III; …

Empirical Fragility Functions And Numerical Parametric Study For Buckling Of Steel Grain Bins Under High Wind Loads, Andrew Ruder

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

While rural infrastructure is critical to the agricultural industry, it has been historically more susceptible to damage and slower to recover following natural disasters than its urban and suburban counterparts. This has been made evident most recently by the events of the August 10, 2020, derecho in which rural regions in Iowa were among the hardest hit areas with sustained windspeeds exceeding 120 mph. Among the most frequently damaged structures in this event were corrugated steel grain bins, which farmers and co-ops use to dry and store certain commodities. Unlike most other critical structures, steel grain bins are not designed …

Evaluation Of Swelling Pressure And Shear Strength Of Inorganic Microfiber-Reinforced Bentonite For The Engineered Barrier System, Jose Maria Ferdinand Victoria Calaunan

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

Nowadays, the permanent disposal of high-level radioactive waste materials has been a primary concern in several countries. The deep geological repository, being the preferred disposal method across the globe, utilizes a network of engineered barriers to prevent the radioactive material from spreading throughout the facility and harming the natural environment. Part of this engineered barrier system (EBS) is the buffer material, which essential function is holding the radioactive waste-containing canister in place. However, the potential generation of desiccation cracks in this buffer material is imminent due to the heat emitted from the radioactive waste. Knowing the capability of inorganic fibers …

Parametric Modeling Of Biomimetic Sharkskin For Wire Edm For Drag Reduction And Hydrophobicity, Joel Maxwell

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

This research sets out to demonstrate the viability of parametric modeling for biomimetic sharkskin in the effort to reduce drag and create a self-cleaning surface. Multiple designs were created to be machined by Wire EDM on stainless steel and titanium and were comparatively tested. Limitations of current manufacturing processes to economically produce naturally occurring structures such as sharkskin, emphasize the need to be able to calculate the most accurate design for a given manufacturing process. By designing a simplified but parametrically consistent model compared to an accurately depicted 3D model of sharkskin, the textured samples produced can be further tested …

Prediction Of Meltpool Depth In Laser Powder Bed Fusion Using In-Process Sensor Data, Part-Level Thermal Simulations, And Machine Learning, Grant King

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

The goal of this thesis is the prevention of flaw formation in laser powder bed fusion additive manufacturing process. As a step towards this goal, the objective of this work is to predict meltpool depth as a function of in-process sensor data, part-level thermal simulations, and machine learning. As motivated in NASA's Marshall Space Flight Center specification 3716, prediction of meltpool depth is important because: (1) it can serve as a surrogate to estimate process status without the need for expensive post-process characterization, and (2) the meltpool depth provides an avenue for rapid qualification of microstructure evolution. To achieve the …

Advancing Statistical Learning And Decision Modeling Using Irregularly-Sampled Multivariate Data For Managing Respiratory Diseases, Maryam Alimohammadi

Graduate Theses and Dissertations

Complex healthcare systems require efficient and effective data-driven decision making in various aspects. As patient data becomes more available, advanced statistical learning and machine learning techniques are applied to improve data-driven decision making. However, patient health data, including clinical trial data, medical records, and electronic health records, are associated with several challenges. Patient health data includes medical information of a patient that may includedemographics, information relating to their health or illness, medications and treatments, etc. They are a combination of static and time series variables, with many censoring and missingness in the data, and are irregularly sampled in most cases. …

Precision Weed Management Based On Uas Image Streams, Machine Learning, And Pwm Sprayers, Jason Allen Davis

Graduate Theses and Dissertations

Weed populations in agricultural production fields are often scattered and unevenly distributed; however, herbicides are broadcast across fields evenly. Although effective, in the case of post-emergent herbicides, exceedingly more pesticides are used than necessary. A novel weed detection and control workflow was evaluated targeting Palmer amaranth in soybean (Glycine max) fields. High spatial resolution (0.4 cm) unmanned aircraft system (UAS) image streams were collected, annotated, and used to train 16 object detection convolutional neural networks (CNNs; RetinaNet, Faster R-CNN, Single Shot Detector, and YOLO v3) each trained on imagery with 0.4, 0.6, 0.8, and 1.2 cm spatial resolutions. Models were …

Investigations Of Prokaryotic Defense Systems, Hannah Domgaard

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Bacteria are constantly threatened with infection by mobile genetic elements (MGE) such as bacteriophage and plasmids. Bacteriophage and plasmids require the bacteria's cellular infrastructure to replicate their genomes. Rampant replication can lead to cell death which is one reason why bacteria have developed a diverse array of immune systems to prevent or limit infection. This thesis studies three types of bacterial immune systems, type IV-A CRISPR-Cas (Clustered Regularly Interspaced Short Palindromic Repeat –CRISPR associated), type V-A2 CRISPR-Cas systems, and Wadjet systems.

The type IV-A system lies adjacent to a dinG-like helicase gene. Research has shown that this system can target …

Linearized Rigid-Body Static And Dynamic Stability Of An Aircraft With A Bio-Inspired Rotating Empennage, Austin J. Kohler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The United States Air Force (USAF) will likely seek to remove the vertical tail of next-generation fighter aircraft. This work seeks to characterize the static and dynamic stability and handling qualities of a vertical-tailless aircraft concept that would satisfy the USAF’s goal. This concept aircraft, one modified with a Bio-Inspired Rotating Empennage (BIRE), does not have a vertical tail, and is instead capable of rotating the horizontal tail about the fuselage axis for maneuvering. The dynamic characteristics of the BIRE-modified aircraft are compared to a baseline unmodified aircraft, similar to the F16, with a traditional vertical tail. Linearized aerodynamic models …

Measuring The Effectiveness Of Light Concentration With The Catoptric Surface, Samatha Kodali

McKelvey School of Engineering Graduate Student Theses & Dissertations

The Catoptric Surface is an array of mirrors arranged on the interior of a large window which serves to manipulate the effects of natural lighting inside the room. The framework for moving the mirrors uses an interface which connects various Raspberry Pis and Arduino Unos to move stepper motors that connect to each mirror and move them as desired by the user. This kind of light manipulation allows the atmosphere of the room to be modified using natural lighting rather than artificial lighting and can be useful for varying the way people interact with a space. The intensity at which …

Water-Soluble Saponins Accumulate In Drought-Stressed Switchgrass And May Inhibit Yeast Growth During Bioethanol Production, Sarvada Hemant Chipkar, Katherine Smith, Elizabeth M. Whelan, Derek J. Debrauske, Annie Jen, Katherine A. Overmyer, Andrea Senyk, Larkin Hooker-Moericke, Marissa Gallmeyer, Joshua J. Coon, A. Daniel Jones, Trey K. Sato, Rebecca G. Ong

Michigan Tech Publications, Part 1

Background: Developing economically viable pathways to produce renewable energy has become an important research theme in recent years. Lignocellulosic biomass is a promising feedstock that can be converted into second-generation biofuels and bioproducts. Global warming has adversely affected climate change causing many environmental changes that have impacted earth surface temperature and rainfall patterns. Recent research has shown that environmental growth conditions altered the composition of drought-stressed switchgrass and directly influenced the extent of biomass conversion to fuels by completely inhibiting yeast growth during fermentation. Our goal in this project was to find a way to overcome the microbial inhibition and …

Mitigating Popularity Bias In Recommendation With Unbalanced Interactions: A Gradient Perspective, Weijieying Ren, Lei Wang, Kunpeng Liu, Ruocheng Guo, Ee-Peng Lim, Yanjie Fu

Research Collection School Of Computing and Information Systems

Recommender systems learn from historical user-item interactions to identify preferred items for target users. These observed interactions are usually unbalanced following a long-tailed distribution. Such long-tailed data lead to popularity bias to recommend popular but not personalized items to users. We present a gradient perspective to understand two negative impacts of popularity bias in recommendation model optimization: (i) the gradient direction of popular item embeddings is closer to that of positive interactions, and (ii) the magnitude of positive gradient for popular items are much greater than that of unpopular items. To address these issues, we propose a simple yet efficient …

Cyber Resilience Analytics For Cyber-Physical Systems, Md Ariful Haque

Electrical & Computer Engineering Theses & Dissertations

Cyber-physical systems (CPSs) are complex systems that evolve from the integrations of components dealing with physical processes and real-time computations, along with networking. CPSs often incorporate approaches merging from different scientific fields such as embedded systems, control systems, operational technology, information technology systems (ITS), and cybernetics. Today critical infrastructures (CIs) (e.g., energy systems, electric grids, etc.) and other CPSs (e.g., manufacturing industries, autonomous transportation systems, etc.) are experiencing challenges in dealing with cyberattacks. Major cybersecurity concerns are rising around CPSs because of their ever-growing use of information technology based automation. Often the security concerns are limited to probability-based possible attack …

Assembly Of Ceramic Particles In Aqueous Suspensions Induced By High-Frequency Ac Electric Field, James E. John Iv

Mechanical & Aerospace Engineering Theses & Dissertations

Ceramic materials processed using colloidal methods have been the focus of a great deal of research aimed at tailoring the final structure and microstructure of the finished ceramic sample. To this end, various external field effects have been investigated to modify the suspension microstructure without manipulating the ceramic particles directly. In a previous work in the field of ice templating it has been shown that AC electric fields are able to produce microstructural changes in ice templated ceramics that have significantly improved the final mechanical properties. However, the mechanisms for this process are still not well understood in ceramics.

To …

Numerical Simulation Of Electroosmotic Flow Of Viscoelastic Fluid In Microchannel, Jianyu Ji

Mechanical & Aerospace Engineering Theses & Dissertations

Electroosmotic flow (EOF) has been widely used in various biochemical microfluidic applications, many of which often involve the use of viscoelastic non-Newtonian fluids. Due to the existence of the elastic effect, the viscoelastic EOF develops into chaotic flow under extremely low Reynolds numbers, which is known as elastic turbulence. The mechanism of elastic turbulence in electroosmotic flow remains unclear. Numerical simulation plays an important role in understanding the mechanisms of elastic turbulence. This dissertation is aimed to study the EOF of viscoelastic fluids in constriction microchannels under various direct current (DC) and alternating current (AC) electric fields. First, the EOF …

Detection, Tracking, And Classification Of Aircraft And Birds From Multirotor Small Unmanned Aircraft Systems, Chester Valentine Dolph

Electrical & Computer Engineering Theses & Dissertations

The ability for small Unmanned Aircraft Systems (sUAS) to safely operate beyond visual line of sight (BVLOS) is of great interest to governments, businesses, and scientific research. One critical element for sUAS to operate BVLOS is the capability to avoid other air traffic. While many aircraft will be cooperative and broadcast their locations using Automatic Dependent Surveillance Broadcast (ADS-B), it is expected that many aircraft will remain non-cooperative – meaning they do not communicate position or flight plan to other aircraft. Avoiding mid-air collisions with non-cooperative aircraft is a critical limitation to widespread sUAS flying BVLOS. Examples of non-cooperative traffic …

Development And Validation Of A Three-Dimensional Optical Imaging System For Chest Wall Deformity Measurement, Nahom Kidane

Electrical & Computer Engineering Theses & Dissertations

Congenital chest wall deformities (CWD) are malformations of the thoracic cage that become more pronounced during early adolescence. Pectus excavatum (PE) is the most common CWD, characterized by an inward depression of the sternum and adjacent costal cartilage. A cross-sectional computed tomography (CT) image is mainly used to calculate the chest thoracic indices. Physicians use the indices to quantify PE deformity, prescribe surgical or non-surgical therapies, and evaluate treatment outcomes. However, the use of CT is increasingly causing physicians to be concerned about the radiation doses administered to young patients. Furthermore, radiographic indices are an unsafe and expensive method of …

Panodepth – Panoramic Monocular Depth Perception Model And Framework, Adley K. Wong

Master's Theses

Depth perception has become a heavily researched area as companies and researchers are striving towards the development of self-driving cars. Self-driving cars rely on perceiving the surrounding area, which heavily depends on technology capable of providing the system with depth perception capabilities. In this paper, we explore developing a single camera (monocular) depth prediction model that is trained on panoramic depth images. Our model makes novel use of transfer learning efficient encoder models, pre-training on a larger dataset of flat depth images, and optimizing the model for use with a Jetson Nano. Additionally, we present a training and optimization framework …

Lung Cancer Type Classification, Mohit Ramajibhai Ankoliya

Electronic Theses, Projects, and Dissertations

Lung cancer is the third most common cancer in the U.S. This research focuses on classifying lung cancer cells based on their tumor cell, shape, and biological traits in images automatically obtained by passing through the

convolutional layers. Additionally, I classify whether the lung cell is adenocarcinoma, large cell carcinoma, squamous cell carcinoma, or normal cell carcinoma. The benefit of this classification is an accurate prognosis, leading to patients receiving proper therapy. The Lung Cancer CT(Computed Tomography) image dataset from Kaggle has been drawn with 1000 CT images of various types of lung cancer. Two state-of-the-art convolutional neural networks (CNNs) …

The Observation Of Smart Camera Security, Shun-Hsin Wang

Electronic Theses, Projects, and Dissertations

At present, as the Internet of Thing (IoT) is increasingly widely used in human life, how to protect IoT devices from Malware attack has become an inevitable problem. This project is an analysis of two malwares and how they impact the Internet of Thing (IoT), especially the smart cameras common in people’s life and used in the enterprise. The analysis looks at the vulnerabilities of smart cameras and how Mirai malware and Persirai malware take advantage to these vulnerabilities to attack smart cameras within the network through the simulation process. Through the simulation, although both malwares were implemented using different …

Analysis For An Efficient Operation Of Solar Power Plants In India Using Different Variables/Parameters, Sonal Bansi Shinde

Electronic Theses, Projects, and Dissertations

Vast renewable energy facilities rely heavily on accurate predictions of future solar power output.  This study investigated the various factors causing poor, inefficient operation of Solar Plants and different methods to identify underperforming equipment. The main questions are: Q1: How can we predict electricity generation over the next several days so that the plant can run at peak efficiency? Q2: How can we figure out the exact maintenance needs of any power plant?  Q3: How do we identify faulty equipment to improve its efficiency to improve overall performance? and Q4: What are the different factors that are causing an inefficient …

A Study Of Heart Disease Diagnosis Using Machine Learning And Data Mining, Intisar Ahmed

Electronic Theses, Projects, and Dissertations

Heart disease is the leading cause of death for people around the world today. Diagnosis for various forms of heart disease can be detected with numerous medical tests, however, predicting heart disease without such tests is very difficult. Machine learning can help process medical big data and provide hidden knowledge which otherwise would not be possible with the naked eye. The aim of this project is to explore how machine learning algorithms can be used in predicting heart disease by building an optimized model. The research questions are; 1) What Machine learning algorithms are used in the diagnosis of heart …

The Living Breakwaters Pdr Efforts Econcrete Resource Analysis, Guianina Ferrari, Shervon Stephens, Calvin O. Walters Jr.

Publications and Research

On October 29, 2012, Superstorm Sandy impacted 443,000 people and caused nearly $19 billion (about $58 per person in the US) worth of damage within New York City. As part of the New York City infrastructure reparation plan, the Living Breakwaters project in Tottenville addressed coastal resilience, allocating $100M of public funds to a series of artificial breakwaters by the southwest coast of Staten Island. Each breakwater is constructed and designed to mitigate water flow in storm events. ECOncrete, a primary element of the breakwater, is a specialty cast cementitious product that is marine organism-friendly that encourages biocalcification and photosynthesis. …

Nexuscapes: A Landscape Approach For A Transdisciplinary Water-Energy-Food Nexus Decision-Making Process, Fortino Acosta

UNLV Theses, Dissertations, Professional Papers, and Capstones

This study develops a reliable transdisciplinary framework for complex ecological and social systems by characterizing, mapping, typifying, assessing, and testing enhanced water-energy-food nexus scenarios under critical time constraints, specialized skills, or sensitive data accessibility. Detached management of limited essential resources like fresh water, reliable energy from renewable sources, and nutritious food can jeopardize regional economies and governance. Using a novel landscape approach, this study recommends a decision-making the framework focused on the circular economy that induces collaboration among diverse sectors and brings strategic coordination, specificity, and magnitude to the proposed solutions. The study elaborates on a decision-making tool that integrates …

Identification Of Factors Contributing To Traffic Crashes By Analysis Of Text Narratives, Cristian D. Arteaga-Sanchez

UNLV Theses, Dissertations, Professional Papers, and Capstones

The fatalities, injuries, and property damage that result from traffic crashes impose a significant burden on society. Current research and practice in traffic safety rely on analysis of quantitative data from crash reports to understand crash severity contributors and develop countermeasures. Despite advances from this effort, quantitative crash data suffers from drawbacks, such as the limited ability to capture all the information relevant to the crashes and the potential errors introduced during data collection. Crash narratives can help address these limitations, as they contain detailed descriptions of the context and sequence of events of the crash. However, the unstructured nature …

Application Of Experimentally Calibrated Numerical Models For Prediction Of Composite Masonry Prism Strength, James Bristow

UNLV Theses, Dissertations, Professional Papers, and Capstones

The composite masonry prism test is a common laboratory test to determine the compressive strength of a set of masonry prisms (f’mt) to verify that the composite masonry prism assembly, and more importantly, the constituent materials, are providing adequate strength. While constructing masonry structures, the subcontractors, designers, and inspectors rarely provide continuous supervision or inspection of the construction process. Accordingly, verification of grout mix design, mixed proportions, proper installation of blocks, placement of mortar, dimensions of joints, etc. are more traditionally performed on a periodic basis instead. However, through the use and review of the composite masonry prism test results, …