Engineering Commons^™

Hyperspectral Image Analysis Of Food For Nutritional Intake, Shirin Nasr Esfahani

UNLV Theses, Dissertations, Professional Papers, and Capstones

The primary object of this dissertation is to investigate the application of hyperspectral technology to accommodate for the growing demand in the automatic dietary assessment applications. Food intake is one of the main factors that contribute to human health. In other words, it is necessary to get information about the amount of nutrition and vitamins that a human body requires through a daily diet. Manual dietary assessments are time-consuming and are also not precise enough, especially when the information is used for the care and treatment of hospitalized patients. Moreover, the data must be analyzed by nutritional experts. Therefore, researchers …

Towards High-Efficient Broadband Omnidirectional Light-Trapping: Discrepancy-Assisted 2d/3d Deterministic Quasi-Random Nanostructure Design, Optimization, And Fabrication, Yihong Zhao

UNLV Theses, Dissertations, Professional Papers, and Capstones

Recently, nano-scaled surface decoration has brought significant advancement and exciting new possibilities to light management. Numerous nanostructure patterns have been explored, wherein the quasi-random nanostructures (QRNs) present a promising path in manipulating light to increase the photon flux over the broadband spectra for optical (e.g., photovoltaic) devices. However, due to the infinite number of QRNs, it is difficult to directly design and fabricate the exact QRN pattern as desired to achieve the optimized light-trapping capability. To overcome this obstacle, we 1) digitize the traditional continuous QRNs into meshes and then map the meshes to binary matrices, which can be deterministically …

Modeling Triaxial Testing With Flexible Membrane To Investigate Effects Of Particle Size On Strength And Strain Properties Of Cohesionless Soil, Thang Pham, Md. Wasif Zaman, Thuy Vu

Civil Engineering Faculty Publications

A 3D DEM model using Particle Flow Code (PFC3D) software was developed utilizing a bonded-ball flexible membrane approach to study cohesionless soil as a discontinuous discrete material. This approach is not yet widely used because of its complexity and high computational cost, but it allowed the authors to observe the stress-strain curves of triaxial specimens, to single out effects of individual factors on the strength and strain properties, and to observe the formation of the shear band and failure surface. The 3D model was calibrated and verified with experimental data, and a sensitivity analysis was carried out for the microparameters. …

Manufacturing And Characterization Of Continuous Nanofiber-Reinforced Composites, Lucas Barry

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

Fiber-reinforced composite laminates are some of the most advanced structural materials available. However, delamination remains a critical challenge due to its prevalence in structures and ability to cause catastrophic failure. Recently, high-temperature composites are at the forefront of polymer-matrix composites research, but they are prone to microcracking followed by delamination. Nanoreinforcement of interfaces by continuous nanofibers has been proposed earlier at UNL and produced increased interlaminar fracture resistance in conventional advanced composites. However, no studies have yet been conducted on emerging high-temperature composites. Also, there is insufficient information on the translatability of observed modes I and II interlaminar fracture toughness …

Wind Tunnel Modeling Of Jack Rabbit Ii Mock Urban Environment Gas Concentration Measurements, Sami S. Fares

Graduate Theses and Dissertations

The 2015 Jack Rabbit (JR) II field trials were conducted to improve understanding of the denser-than-air dispersion of chlorine in an urban environment. The field study involved five large-scale, outdoor release trials of chlorine in a mock urban environment (MUE) at Dugway Proving Ground (DPG). Various instrumentation was deployed, including JazTM Ultraviolet-Visible (UV-Vis) point sensors capable of measuring gas-phase chlorine concentration throughout the mock urban array.

The Chemical Hazards Research Center (CHRC) was tasked by the Chemical Security Analysis Center (CSAC) with the Mock Urban Wind Tunnel (MUWT) program to study the 2015 JR II Trials at wind tunnel scale. …

High-Isolation Antenna Technique For Cubesat-Borne, Continuous-Waveform Radar, Logan E. Voigt

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Radar is important in target tracking, imaging, and weather prediction applications. As technology is increasingly miniaturized, there is a push for smaller radar. Research and exploration in outer space also benefit from small, low-power technologies. The NASA Jet Propulsion Laboratory’s RainCube was the first successful CubeSat-borne radar. A CubeSat is a type of small satellite that conforms to specific size and weight standards. Radar technology benefits from additional research on how to further miniaturize radar payloads.

Integrating the transmit and receive antennas on the solar panels removes the need for antenna-deployment mechanisms, preserving space on the CubeSat. This thesis also …

Sustain Water Conservation Behaviors Using Nonparametric Ranking And Social Marketing, Mahmudur Rahman Aveek

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Circulation of water use feedback and conservation messaging are strategies implemented to reduce water demand on a short-term (seasonal) basis. Often considered a less impactful strategy than other tactics such as price increments and usage restrictions, authorities mostly use feedback in informational campaigns with a focus to apprise users about their water use. Such conservation programs have had limited success that has been attributed to the fact that the information provided with the feedback campaigns was generic and did not motivate users enough to sustain their water-saving behaviors. However, the advent of disaggregation technologies that can provide appliance-wise water use …

Advancing The Cyberinfrastructure For Smart Water Metering And Water Demand Modeling, Nour A. Attallah

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

With rapid growth of urban populations and limited water resources, achieving an appropriate balance between water supply capacity and residential water demand poses a significant challenge to water supplying agencies. With the recent emergence of smart metering technology, where water use can be monitored and recorded at high resolution (e.g., observations of water use every 5 seconds), most existing research has been aimed at providing water managers with detailed information about the water use behavior of their consumers and the performance of water using fixtures. However, replacing existing meters with smart meters is expensive, and effectively using data produced by …

Bugs Buy Steady Releases From Hydropower Producers To Encourage More Synergistic Reservoir Management, Moazzam Ali Rind

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Hydropower generated from dams has significant economic value, however, that value is achieved at the cost of native ecosystem devastation. Here, we have estimated loss in hydropower revenue due to inclusion of the steady low flow days –Bug Flow Experiments. We developed a linear optimization model and constraint method that restrict the number of steady low flow days while maximizes the hydropower revenue generation. The results suggested that increase in release volume will benefit both the objectives (win-win scenario), energy price differential between on-and off-peak periods controls the position and shape of tradeoff curves, and offset release does not have …

Using Computational Fluid Dynamics To Predict Flow Through The West Crack Breach Of The Great Salt Lake Railroad Causeway, Michael Rasmussen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Great Salt Lake in Utah, USA, is a terminal, saline lake and is divided into two primary sections (northern and southern) by an east-to-west railroad causeway. Shortly after completion of the earth-fill causeway in the late 1950s, the two sections became dramatically different with differences in water surface elevation and water density. These differences cause the formation of a unique flow behavior commonly referred to as a density-driven exchange flow or bi-directional flow; a behavior observed in other lake and ocean settings where two fluids of differing densities interact. Measuring these exchange flows is a priority for lake managers …

Speed Of Small Droplets On Repellent Surfaces, Addison J. Litton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A droplet of fluid can slide or roll down an angled surface if the droplet doesn’t stick to the plate (e.g., droplets on glass). The most common surface to allow for such this motion are hydrophobic surfaces. One example is a freshly waxed car where the rain beads up and rolls off. Another example is if a pan is heated to a high enough temperature then when small amounts of water are added the droplet will skitter around on the surface for a moment before boiling away. This high temperature effect where droplets rest on a vapor layer underneath cause …

A Computational Approach To Evaluating Curricular Alignment To The United Nations Sustainable Development Goals, Philippe Lemarchand, Mick Mckeever, Cormac Macmahon, Philip Owende

Articles

The United Nations (UN) considers universities to be key actors in the pursuit of the Sustainable Development Goals (SDGs). Yet, efforts to evaluate the embeddedness of the SDGs in university curricula tend to rely on manual analyses of curriculum documents for keywords contained in sustainability lexica, with little consideration for the diverse contexts of such keywords. The efficacy of these efforts, relying on expert co-elicitation in both subject-matter contexts and sustainability, suffers from drawbacks associated with keyword searches, such as limited coverage of key concepts, difficulty in extracting intended meaning and potential for greenwashing through “keyword stuffing.” This paper presents …

Passage Probability Of Woody Debris Elements And Accumulations At I- And V-Shaped Rock Weirs, Kathryn Margetts

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The transport and accumulation of driftwood or large woody debris (LWD) in mountain streams is a natural part of catchment health and river connectivity. At hydraulic structures, the presence of LWD may impact flow efficiency and influence upstream water depth. LWD has been studied at a variety of spillways and weir types, however, little is known about its interaction at rock weirs. This study investigated factors affecting the passage of individual LWD elements and any LWD accumulations at rock weirs, as well as potential impacts upstream of LWD accumulations through field-informed scaled model testing. Observations of LWD at rock weirs …

Highly Variable Rainfall-Runoff Patterns Across Burned Mountainous Watersheds In The Colorado River Headwaters, Haley Anne Canham

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Wildfires can contribute to enhanced flooding, erosion, debris flows, sediment transport, and water quality changes that impact downstream infrastructure, water users, and aquatic habitat. With increasing wildfire risk in the western U.S. due to a changing climate, understanding post-wildfire rainfall-runoff patterns and controls is critical for continued water resources security. To improve understanding of post-wildfire rainfall-runoff patterns and controls, we developed a transparent, repeatable analysis framework to collect precipitation and streamflow data, identify paired rainfall-runoff events, and analyze these events to evaluate post-wildfire rainfall-runoff patterns and controls. To automate the rainfall-runoff event identification, the Rainfall-Runoff Event Detection and Identification (RREDI) …

Upstream Methods For Enhancing Engineered Curcumin Biosynthesis, Caleb D. Barton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Curcumin is a bright orange compound with myriad applications for human health and wellness. Curcumin occurs naturally in the plant Curcuma longa (commonly known as turmeric) but must be extracted from the roots in an environmentally unfriendly fashion to obtain commercially relevant amounts of the compound. In addition, extraction of curcumin from turmeric spice yields a mixture of various curcuminoids, presenting an issue for isolating it in its pure form and complicating its use in clinical settings.

Heterologous biosynthetic production of curcumin in Escherichia coli has been used extensively as a viable alternative to plant extraction but suffers from poor …

Lentiviral Vector Production At High Cell Density By Transient Transfection Of Suspended Culture Hek Cells, Jacob G. Accordino

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Viral vectors are gene carriers that efficiently deliver therapeutic gene constructs to target cells. Viral vectors are frequently produced in suspension-growing cells of mammalian origin, referred to as packaging cells. Lentiviral vectors have become widely used as gene vectors since they were initially developed two and a half decades ago, particularly in research settings. The advantages of lentiviral vectors for treating diseases of genetic origin have driven research into their large-scale manufacture for clinical settings. Currently, three main challenges exist that limit mass production of lentiviral vectors. First, plasmid DNA used in the production process is very expensive. Second, high …

Multidisciplinary Reference Solutions For Performance-Optimized Aircraft Wings With Tailored Aerodynamic Load Distributions, Jeffrey D. Taylor

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Morphing wings, or wings that can change shape during flight, have the potential to substantially reduce the amount of fuel consumed by an aircraft over the course of its flight. However, the extent to which these wings can reduce fuel consumption depends on the design of the wing, including its aerodynamic efficiency and its structural layout, and how the aircraft flies, including its flight altitude and speed. Correctly predicting how these design and operational characteristics interact is critical to predicting how wing morphing may affect aircraft fuel consumption. Many computer prediction tools exist that include the effects of these interactions, …

Control Mapping Methodology For Tailless Morphing-Wing Aircraft, Zachary S. Montgomery

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Advanced aircraft designs tend to have several control surfaces or devices that affect the flight of the aircraft. It is difficult or even impossible for a pilot to directly control each of these devices and fly the aircraft well. Therefore, a control mapping logic is needed to take typical pilot commands and map them to what the control devices should do to achieve the pilot’s commands. This work presents a methodology for determining this control mapping logic using two different approaches. The first uses a theoretical approach based on lifting-line theory, while the second leverages computational methods. The methodology consists …

Lifetime Maximization In Underwater Wireless Communication Networks, Kazi Yasin Islam, Iftekhar Ahmad, Daryoush Habibi, Jiong Jin, Muhammad Waqas

Research outputs 2022 to 2026

The rise in demand for underwater wireless communication networks (UWCN) has been driven by the emergence of new applications including unmanned underwater vehicles, deep-sea exploration, maritime and underwater archaeology research, and diver communications. For various applications, underwater network lifetime must be long, since unlike terrestrial sensor networks, it is a major job to change/recharge node batteries in underwater environments. In this paper, we introduce a solution where critical nodes in a UWCN are periodically recharged by small renewable energy sources. Further, a caching mechanism is introduced to relieve critical nodes of heavy workload when their residual energies run low. By …

Deep Learning For Robust Adaptive Inverse Control Of Nonlinear Dynamic Systems: Improved Settling Time With An Autoencoder, Nuha A. S. Alwan, Zahir M. Hussain

Research outputs 2022 to 2026

An adaptive deep neural network is used in an inverse system identification setting to approximate the inverse of a nonlinear plant with the aim of constituting the plant controller by copying to the latter the weights and architecture of the converging deep neural network. This deep learning (DL) approach to the adaptive inverse control (AIC) problem is shown to outperform the adaptive filtering techniques and algorithms normally used in adaptive control, especially when in nonlinear plants. The deeper the controller, the better the inverse function approximation, provided that the nonlinear plant has an inverse and that this inverse can be …

Investigating The Microstructural And Mechanical Properties Of Novel Ternary Reinforced Aa7075 Hybrid Metal Matrix Composite, Afnan Haider Khan, Syed Ahmad Ali Shah, Farheen Umar, Uneeb Noor, Rizwan Mahmood Gul, Khaled Giasin, Muhammad Aamir

Research outputs 2022 to 2026

This study investigates the comparison of the microstructural and mechanical properties of a novel ternary reinforced AA7075 hybrid metal matrix composite. Four samples, including AA7075 (base alloy), AA7075-5wt % SiC (MMC), AA7075-5wt %SiC-3wt % RHA (s-HMMC), and AA7075-5wt % SiC-3wt % RHA-1wt % CES (n-HMMC) were developed using the stir casting liquid metallurgy route, followed by the heat treatment. The experimental densities corresponded with the theoretical values, confirming the successful fabrication of the samples. A minimum density of 2714 kg/m3 was recorded for the n-HMMC. In addition, the highest porosity of 3.11 % was found for n-HMMC. Furthermore, an increase …

Thermodynamic Modeling Of Hydrogen–Water Systems With Gas Impurity At Various Conditions Using Cubic And Pc-Saft Equations Of State, Amer Alanazi, Saleh Bawazeer, Muhammad Ali, Alireza Keshavarz, Hussein Hoteit

Research outputs 2022 to 2026

Hydrogen (H2) has emerged as a viable solution for energy storage of renewable sources, supplying off-seasonal demand. Hydrogen contamination due to undesired mixing with other fluids during operations is a significant problem. Water contamination is a regular occurrence; therefore, an accurate prediction of H2-water thermodynamics is crucial for the design of efficient storage and water removal processes. In thermodynamic modeling, the Peng–Robinson (PR) and Soave Redlich–Kwong (SRK) equations of state (EoSs) are widely applied. However, both EoSs fail to predict the vapor-liquid equilibrium (VLE) accurately for H2-blend mixtures with or without fine-tuning binary interaction parameters due to the polarity of …

Incorporating Immersive Learning Into Biomedical Engineering Laboratories Using Virtual Reality, Megan Wilkerson, Vitali V. Maldonado, Srikanth Sivaraman, Raj R. Rao, Mostafa Elsaadany

Biomedical Engineering Faculty Publications and Presentations

Background

The Covid-19 pandemic caused a sudden shift towards remote learning, moving classes to online formats. Not exempt from this switch, laboratory courses traditionally taught in-person were also moved to remote methods, costing students the opportunity to learn these skills hands-on. In order for instructors to provide course materials effectively and engagingly, non-traditional methods should be explored.

Virtual reality (VR) has become more accessible in recent years. VR simulations have been used for many years as educational tools in high-risk settings such as flight or medical simulations. Immersive VR videos implemented in a remote laboratory course could provide the students …

Recrystallization Of Cu(In,Ga)Se2 Semiconductor Thin Films Via Metal Halides Treatment, Deewakar Poudel

Electrical & Computer Engineering Theses & Dissertations

The advancement of low-cost, highly efficient solar cell devices is a major technological challenge demanding suitable materials and fabrication processes. Polycrystalline Cu(In,Ga)Se_{2 (}CIGS) appear to be one of the most promising semiconductor in thin film photovoltaic technology due to its bandgap tunability, high absorption coefficient, and tendency to produce high efficiency solar cells. High-quality CIGS materials fabricated via a three-stage co-evaporation process can convert primary materials into devices with power conversion efficiency above 23%. Increasing the deposition rate and decreasing the deposition temperature, while maintaining high efficiency, is the major concern for the CIGS solar cells to compete …

Role Of Structural Hierarchy In Multiscale Material Systems, Siavash Sattar

Mechanical & Aerospace Engineering Theses & Dissertations

Multiscale material systems derive their effective mechanical properties through a hierarchical organization of their structural elements and components. The hierarchy of a material is related to its effective properties, material processing, and composition. The hierarchy can be defined as an identifiable structural component with a specific size scale, such as the individual fibers collimated into platelets arranged randomly and producing a complex composite system or the lamellar structure in freeze-casted ceramic with the variation of in-plane orientation. In this study, the role of the structural hierarchy on the effective mechanical response and failure behavior of three complex material systems was …

Predictors Of Email Response: Determinants Of The Intention Of Not Following Security Recommendations, Miguel Angel Toro-Jarrin

Engineering Management & Systems Engineering Theses & Dissertations

Organizations and government leaders are concerned about cyber incidents. For some time, researchers have studied what motivates people to act in ways that put the confidentiality, integrity, and availability of information in organizations at risk. Still, several areas remained unexplored, including the role of employees’ evaluation of the organizational systems and the role of value orientation at work as precursors of secure and insecure actions in relation to information technologies (information security [IS] action). The objective of this research project was to examine how the evaluations of formal and informal security norms are associated with the intention to follow them …

Adaptive Risk Network Dependency Analysis Of Complex Hierarchical Systems, Katherine L. Smith

Computational Modeling & Simulation Engineering Theses & Dissertations

Recently the number, variety, and complexity of interconnected systems have been increasing while the resources available to increase resilience of those systems have been decreasing. Therefore, it has become increasingly important to quantify the effects of risks and the resulting disruptions over time as they ripple through networks of systems. This dissertation presents a novel modeling and simulation methodology which quantifies resilience, as impact on performance over time, and risk, as the impact of probabilistic disruptions. This work includes four major contributions over the state-of-the-art which are: (1) cyclic dependencies are captured by separation of performance variables into layers which …

Interpreting Trajectories From Multiple Views: A Hierarchical Self-Attention Network For Estimating The Time Of Arrival, Zebin Chen, Xiaolin Xiao, Yue-Jiao Gong, Jun Fang, Nan Ma, Hua Chai, Zhiguang Cao

Research Collection School Of Computing and Information Systems

Estimating the time of arrival is a crucial task in intelligent transportation systems. Although considerable efforts have been made to solve this problem, most of them decompose a trajectory into several segments and then compute the travel time by integrating the attributes from all segments. The segment view, though being able to depict the local traffic conditions straightforwardly, is insufficient to embody the intrinsic structure of trajectories on the road network. To overcome the limitation, this study proposes multi-view trajectory representation that comprehensively interprets a trajectory from the segment-, link-, and intersection-views. To fulfill the purpose, we design a hierarchical …

Submodularity And Local Search Approaches For Maximum Capture Problems Under Generalized Extreme Value Models, Tien Thanh Dam, Thuy Anh Ta, Tien Mai

Research Collection School Of Computing and Information Systems

We study the maximum capture problem in facility location under random utility models, i.e., the problem of seeking to locate new facilities in a competitive market such that the captured user demand is maximized, assuming that each customer chooses among all available facilities according to a random utility maximization model. We employ the generalized extreme value (GEV) family of discrete choice models and show that the objective function in this context is monotonic and submodular. This finding implies that a simple greedy heuristic can always guarantee a (1−1/e) approximation solution. We further develop a new algorithm combining a greedy heuristic, …

Fabrication Of Nb3Sn By Magnetron Sputtering For Superconducting Radiofrequency Application, Md Nizam Sayeed

Electrical & Computer Engineering Theses & Dissertations

Particle accelerators are considered as an important device that has wide applications in cancer treatment, sterilizing waste, preserving foods, ion implantation in semiconductor industry, and in production of isotopes for medical applications. Superconducting radiofrequency (SRF) cavities are the building blocks of a linear particle accelerator. Current particle accelerators use niobium (Nb) superconductors as the sheet material to fabricate a single SRF cavity for particle acceleration. With better superconducting properties (critical temperature T_c ~ 18.3 K, superheating field H_sh~ 400 mT), Nb₃Sn is considered a potential candidate in SRF technology. Magnetron sputtering is a promising deposition …