Engineering Commons^™

The Effects Of Noise On Parametrically Excited Systems With Nonlinear Damping, Donghao Li

Theses and Dissertations

Parametric oscillators are a class of resonating systems in which a parameter, such as stiffness in a mechanical system or capacitance in an electrical system, is periodically modulated in order to alter the system response in a desired manner. A resonance effect occurs when the pump frequency is near twice of resonant frequency. Such systems are said to be “parametrically pumped,” and this pump can, above a certain amplitude threshold, destabilize the system in the absence of nonlinearities. Parametric resonance is widely observed in nature and has been employed in a large variety of engineered systems, most notably in micro-electro-mechanical …

Design And Analysis Of A Pipe And Pump System Constructed To Connect Port Canaveral To The Banana River, Nicole Ann Mcclain

Theses and Dissertations

The Indian River Lagoon (IRL) has hosted an extensive array of plants and animals throughout its lifetime, having one of the greatest species’ diversity of all North American estuaries. In addition to the variety of marine wildlife that is supported by the IRL, the system is also a recreational and economic resource for the counties bordering it. The biological integrity of the IRL, however, has shown evidence of decline in the last few decades, due to impaired water quality caused by pollution and disruptions to natural circulation patterns. If far-reaching changes are made to repair the water quality of the …

Data Science For Building Energy Efficiency: A Comprehensive Text-Mining Driven Review Of Scientific Literature, Mahmoud M. Abdelrahman, Sicheng Zhan, Clayton Miller, Adrian Chong

Research Collection College of Integrative Studies

The ever-changing data science landscape is fueling innovation in the built environment context by providing new and more effective means of converting large raw data sets into value for professionals in the design, construction and operations of buildings. The literature developed due to this convergence has rapidly increased in recent years, making it difficult for traditional review approaches to cover all related papers. Therefore, this paper applies a natural language processing (NLP) method to provide an exhaustive and quantitative review.Approximately 30,000 scientific publications were retrieved from the Elsevier API to extract the relationship between data sources, data science techniques, and …

Promoting Diversity In Academic Research Communities Through Multivariate Expert Recommendation, Omar Salman

Graduate Theses and Dissertations

Expert recommendation is the process of identifying individuals who have the appropriate knowledge and skills to achieve a specific task. It has been widely used in the educational environment mainly in the hiring process, paper-reviewer assignment, and assembling conference program committees. In this research, we highlight the problem of diversity and fair representation of underrepresented groups in expertise recommendation, factors that current expertise recommendation systems rarely consider. We introduce a novel way to model experts in academia by considering demographic attributes in addition to skills. We use the h-index score to quantify skills for a researcher and we identify five …

A Computational Study Of Radiation Damage In Bilayer Silicon-Gold Structures, Cameron Hopper

Graduate Theses and Dissertations

Irradiation from sources such as nuclear reactors bombard materials with neutrons and heavy ions. The primary consequence of this irradiation is the displacement of atoms from their atomic structure. As the structure becomes damaged, the mechanical properties can change. Eventually, this can result in a failure due to embrittlement. This type of damage is hard to detect and can result in sudden, unexpected failure. Therefore, focusing on managing the consequences of irradiation has been a heavily researched topic. To manage irradiation, the focus is primarily to manage the voids and interstitials that appear during irradiation. Grain boundaries and amorphous regions …

Development Of A Reference Design For Intrusion Detection Using Neural Networks For A Smart Inverter, Ammar Mohammad Khan

Graduate Theses and Dissertations

The purpose of this thesis is to develop a reference design for a base level implementation of an intrusion detection module using artificial neural networks that is deployed onto an inverter and runs on live data for cybersecurity purposes, leveraging the latest deep learning algorithms and tools. Cybersecurity in the smart grid industry focuses on maintaining optimal standards of security in the system and a key component of this is being able to detect cyberattacks. Although researchers and engineers aim to design such devices with embedded security, attacks can and do still occur. The foundation for eventually mitigating these attacks …

Investigation Of Membrane Based Processes For Biomedical Applications, Efecan Pakkaner

Graduate Theses and Dissertations

As substantial developments were achieved in nanotechnology and polymer engineering, especially in the last few decades, the use of membranes and membrane-based procedures was found to be expanding into more and more research and development areas; including biological engineering, life sciences and biomedical engineering. Not only have they been the main focus of meaningful research, but they have also been the main pieces of the solutions to very thorny problems encountered within a wide range of applications from microfluidics to water treatment, thanks to their versatility, cost-effectiveness and biocompatibility, when compared to conventional separation techniques. To celebrate and embrace these …

Novel Eco-Friendly, Recycled Composites For Improved Ca Road Surfaces, Daniel Whisler, Rafael Gomez Consarnau, Ryan Coy

Mineta Transportation Institute

The continued use of structural plastics in consumer products, industry, and transportation represents a potential source for durable, long lasting, and recyclable roadways. Costs to dispose of reinforced plastics can be similar to procuring new asphalt with mechanical performance exceeding that of the traditional road surface.

This project examines improved material development times by leveraging advanced computational material models based on validated experimental data. By testing traditional asphalt and select carbon and glass reinforced composites, both new and recycled, it is possible to develop a finite element simulation that can predict the material characteristics under a number of loads virtually, …

Performance Testing Of Hot Mix Asphalt Modified With Recycled Waste Plastic, Shadi Saadeh, Pritam Katawał

Mineta Transportation Institute

Plastic pollution has become one of the major concerns in the world. Plastic waste is not biodegradable, which makes it difficult to manage waste plastic pollution. Recycling and reusing waste plastic is an effective way to manage plastic pollution. Because of the huge quantity of waste plastic released into the world, industries requiring a large amount of material, like the pavement industry, can reuse some of this mammoth volume of waste plastics. Similarly, the use of reclaimed asphalt pavement (RAP) has also become common practice to ensure sustainability. The use of recycled waste plastics and RAP in HMA mix can …

Efficiently Estimating Survival Signature And Two-Terminal Reliability Of Heterogeneous Networks Through Multi-Objective Optimization, Daniel Bruno Lopes Da Silva

Graduate Theses and Dissertations

The two-terminal reliability problem is a classical reliability problem with applications in wired and wireless communication networks, electronic circuit design, computer networks, and electrical power distribution, among other systems. However, the two-terminal reliability problem is among the hardest combinatorial problems and is intractable for large, complex networks. Several exact methods to solve the two-terminal reliability problem have been proposed since the 1960s, but they have exponential time complexity in general. Hence, practical studies involving large network-type systems resort to approximation methods to estimate the system's reliability. One attractive approach for quantifying the reliability of complex systems is to use signatures, …

A Machine Learning Approach To Understanding Emerging Markets, Namita Balani

Graduate Theses and Dissertations

Logistic providers have learned to efficiently serve their existing customer bases with optimized routes and transportation resource allocation. The problem arises when there is potential for logistics growth in an emerging market with no previous data. The purpose of this work is to use industry data for previously known and well-documented markets to apply data analytic techniques such as machine learning to investigate the uncertainty in a new market. The thesis looks into machine learning techniques to predict miles per stop given historical data. It mainly focuses on Random Forest Regression Analysis, but concludes that additional techniques, such as Polynomial …

Knowledge Discovery From Complex Event Time Data With Covariates, Samira Karimi

Graduate Theses and Dissertations

In particular engineering applications, such as reliability engineering, complex types of data are encountered which require novel methods of statistical analysis. Handling covariates properly while managing the missing values is a challenging task. These type of issues happen frequently in reliability data analysis. Specifically, accelerated life testing (ALT) data are usually conducted by exposing test units of a product to severer-than-normal conditions to expedite the failure process. The resulting lifetime and/or censoring data are often modeled by a probability distribution along with a life-stress relationship. However, if the probability distribution and life-stress relationship selected cannot adequately describe the underlying failure …

Butte Reclamation Evaluation System Field Manual, Pioneer Technical Services, Inc.

Silver Bow Creek/Butte Area Superfund Site

No abstract provided.

Influencing Perceptions Of Stem Through The Best Stem Books List, Scott Bartholomew, Alexia Seymour

Faculty Publications

One day, while discussing engineering and science as potential career options with a female student, we opened a search engine and typed in “engineer” and “scientist.” However, on the first pages of image results, only one female appeared for engineering and only a few females appeared for “scientist” (see Figure 1). This disparity was disturbing—if this student never saw another person like her filling careers in STEM fields, would she ever “picture herself” in those fields?

Design And Validation Of A High-Power, High Density All Silicon Carbide Three-Level Inverter, Zhongjing Wang

Graduate Theses and Dissertations

Transportation electrification is clearly the road toward the future. Compared to internal combustion engine, the electrified vehicle has less carbon-dioxide emission, less maintenance costs and less operation costs. It also offers higher efficiency and safety margin. More importantly, it relieves human’s dependence on conventional fossil energy. In the electrification progress, the revolution of electric traction drive systems is one of the most important milestone. The traction system should keep high efficiency to avoid performance reduction. Moreover, the motor drive should be designed within limited space without sacrificing output power rating. Based on the road map from US Drive Electrical and …

Vibransee: Enabling Simultaneous Visible Light Communication And Sensing, Ila Nitin Gokarn, Archan Misra

Research Collection School Of Computing and Information Systems

Driven by the ubiquitous proliferation of low-cost LED luminaires, visible light communication (VLC) has been established as a high-speed communications technology based on the high-frequency modulation of an optical source. In parallel, Visible Light Sensing (VLS) has recently demonstrated how vision-based at-a-distance sensing of mechanical vibrations (e.g., of factory equipment) can be performed using high frequency optical strobing. However, to date, exemplars of VLC and VLS have been explored in isolation, without consideration of their mutual dependencies. In this work, we explore whether and how high-throughput VLC and high-coverage VLS can be simultaneously supported. We first demonstrate the existence of …

Distributed Modeling Approach For Electrical And Thermal Analysis Of High-Frequency Transistors, Amirreza Ghadimi Avval

Graduate Theses and Dissertations

The research conducted in this dissertation is focused on developing modeling approaches for analyzing high-frequency transistors and present solutions for optimizing the device output power and gain. First, a literature review of different transistor types utilized in high-frequency regions is conducted and gallium nitride high electron mobility transistor is identified as the promising device for these bands. Different structural configurations and operating modes of these transistors are explained, and their applications are discussed. Equivalent circuit models and physics-based models are also introduced and their limitations for analyzing the small-signal and large-signal behavior of these devices are explained. Next, a model …

Experimental And Analysis Of Electromagnetic Characterization Of Biological And Non-Biological Materials In Microwave, Millimeter-Wave, And Terahertz Frequency Bands, Nagma Vohra

Graduate Theses and Dissertations

The goal of this research is to characterize the electromagnetic properties of biological and non-biological materials at terahertz (THz), millimeter-wave, and microwave frequency bands. The biological specimens are measured using the THz imaging and spectroscopy system, whereas the non-biological materials are measured using the microwave and millimeter-wave free-space system. These facilities are located in the Engineering Research Center at the University of Arkansas. The THz imaging system (TPS 3000) uses a Ti-Sapphire laser directed on the photoconductive antennas to generate a THz time domain pulse. Upon using the Fourier Transform, the spectrum of the pulsed THz signal includes frequencies from …

Monte-Carlo-Based Analysis Of Traffic Flow For Urban Air Mobility Vehicles, Sara Ghayouraneh

Graduate Theses and Dissertations

The research conducted in this dissertation is focused on developing a simulation tool that can predict the traffic flow patterns of the Urban Air Mobility vehicles to alleviate some of the challenges related to their traffic management. First, an introduction to the concept of Urban Air Mobility is given, the usage of Automatic Dependent Surveillance-Broadcast systems for Urban Air Mobility vehicles is suggested and dynamic addressing concept is introduced as an answer to a part of air traffic management and address scarcity challenge for Urban air Mobility vehicles. Next, in order to simulate the traffic flow patterns of the Urban …

Direct Torque Control For Silicon Carbide Motor Drives, Mohammad Hazzaz Mahmud

Graduate Theses and Dissertations

Direct torque control (DTC) is an extensively used control method for motor drives due to its unique advantages, e.g., the fast dynamic response and the robustness against motor parameters variations, uncertainties, and external disturbances. Using higher switching frequency is generally required by DTC to reduce the torque ripples and decrease stator current total harmonic distortion (THD), which however can lower the drive efficiency. Through the use of the emerging silicon carbide (SiC) devices, which have lower switching losses compared to their silicon counterparts, it is feasible to achieve high efficiency and low torque ripple simultaneously for DTC drives.

To overcome …

Use Of The Igbt Module In The Active Region To Design A High Current Active Filter, Jorge F. Galarraga

Graduate Theses and Dissertations

Particle accelerators require high-precision magnetic fields on the order or 100ppm or less. This implies that the precision of the associated electrical current in the electromagnet that generates these fields should be smaller than 100ppm. However, conventional switching power supplies cannot offer this precision due to the frequency limitation of the switches. This research considers the use of power electronics devices operating in a linear as an alternative solution to meet the requirements of particle accelerator electromagnets.

This thesis presents the study of an insulated-gate bipolar transistor (IGBT) driver using a new control method that linearizes the IGBT’s collector-emitter voltage …

Computational Modeling Of Black Phosphorus Terahertz Photoconductive Antennas Using Comsol Multiphysics With Experimental Comparison Against A Commercial Lt-Gaas Emitter, Jose Isaac Santos Batista

Graduate Theses and Dissertations

This thesis presents computational models of terahertz (THz) photoconductive antenna (PCA) emitter using COMSOL Multiphysics commercial package. A comparison of the computer simulated radiated THz signal against that of an experimentally measured signal of commercial reference LT-GaAs emitter is presented. The two-dimensional model (2D) aimed at calculating the photoconductivity of a black phosphorus (BP) PCA at two laser wavelengths of 780 nm and 1560 nm. The 2D model was applied to the BP PCA emitter and the LT-GaAs devices to compare their simulated performance in terms of the photocurrent and radiated THz signal pulse. The results showed better performance of …

Deployment Policies To Reliably Maintain And Maximize Expected Coverage In A Wireless Sensor Network, Nicholas T. Boardman

Graduate Theses and Dissertations

The long-term operation of a wireless sensor network (WSN) requires the deployment of new sensors over time to restore any loss in network coverage and communication ability resulting from sensor failures. Over the course of several deployment actions it is important to consider the cost of maintaining the WSN in addition to any desired performance measures such as coverage, connectivity, or reliability. The resulting problem formulation is approached first through a time-based deployment model in which the network is restored to a fixed size at periodic time intervals. The network destruction spectrum (D-spectrum) has been introduced to estimate reliability and …

High Temperature Degradation In Gan-Based Hall Effect Sensors, Alexis Anne Krone

Graduate Theses and Dissertations

This research focuses on understanding the effects of accelerated aging through temperature and environment on novel gallium nitride-based Hall effect magnetic field sensors and determining device reliability under electric vehicle operating conditions. The device reliability was modeled using accelerated aging for the temperatures of 200 °C, 350 °C, 450 °C, and 600 °C under various time steps unique to each temperature and either air, which is identical to operating circumstances, or argon, which would model the hermetic packaging environment. Using a high temperature furnace and oven, devices underwent high temperature storage tests at a chosen temperature and time step. Afterwards, …

Grid Strength Assessment Trough Q-V Modal Analysis And Maximum Loadability Of A Wind-Dominated Power System Using P-Q Regions, Pierre Obed Dorile

Graduate Theses and Dissertations

Climate change is a menace to the existence of the world and policymakers are trying totackle this phenomenon by deploying large-scale wind farms into their grids. Among them, wind energy shows a promising future to substitute the traditional power plants. However, the deployment of these wind farms into the grid is not a panacea that does not pose any challenges to the grid operators. Keeping the power system voltage stable while considering the strength of the transmission grid is among the major challenges facing by the transmission system operators. Amid normal operation and fault conditions, wind farms should help the …

Fabrication And Characterization Of Photodetector Devices Based On Nanostructured Materials: Graphene And Colloidal Nanocrystals, Wafaa Gebril

Graduate Theses and Dissertations

Photodetectors are devices that capture light signals and convert them into electrical signals. High performance photodetectors are in demand in a variety of applications, such as optical communication, security, and environmental monitoring. Among many appealing nanomaterials for novel photodetection devices, graphene and semiconductor colloidal nanocrystals are promising candidates because of their desirable and unique properties compared to conventional materials.

Photodetector devices based on different types of nanostructured materials including graphene and colloidal nanocrystals were investigated. First, graphene layers were mechanically exfoliated and characterized for device fabrication. Self-powered few layers graphene phototransistors were studied. At zero drain voltage bias and room …

Reference Design Of An Online Emulation And Hot-Patching Approach For Power Electronic Controller Validation, Estefano Soria Pearson

Graduate Theses and Dissertations

This thesis aims to develop a reference design of an online security system approach embedded in a power electronic controller for cybersecurity purposes. Cybersecurity in power electronics focuses on reducing vulnerabilities in the system, where most reside in the communication with the hardware devices. Although methods to secure communications lessen the probability and effects of cyber-attacks, discovering vulnerabilities is inevitable. This thesis attempts to provide a fail-safe approach to securing the system by targeting the safety of the power-electronic controller. This approach applies an additional security layer in case of a malicious or accidental controller firmware malfunction.

The online security …

Signal Processing And Data Analysis For Real-Time Intermodal Freight Classification Through A Multimodal Sensor System., Enrique J. Sanchez Headley

Graduate Theses and Dissertations

Identifying freight patterns in transit is a common need among commercial and municipal entities. For example, the allocation of resources among Departments of Transportation is often predicated on an understanding of freight patterns along major highways. There exist multiple sensor systems to detect and count vehicles at areas of interest. Many of these sensors are limited in their ability to detect more specific features of vehicles in traffic or are unable to perform well in adverse weather conditions. Despite this limitation, to date there is little comparative analysis among Laser Imaging and Detection and Ranging (LIDAR) sensors for freight detection …

Nanomaterial-Based Biosensors For Detection Of Salmonella Typhimurium And Avian Influenza Virus H5n1 In Poultry, Xinge Xi

Graduate Theses and Dissertations

This research focused on developing biosensing method and biosensing device for rapid detection of pathogens in poultry: Salmonella Typhimurium and avian influenza virus H5N1. The first part of the dissertation reports an original research on the development of a portable biosensing device for Salmonella detection. The device was designed and constructed based on a previously developed optical biosensing method, using immuno-magnetic nanoparticles to specifically capture target bacteria, and immuno-quantum dot beads to label the target bacteria for fluorescence detection. All the actions of sample mixing, magnetic separation, and fluorescence detection were controlled automatically in a disposable microfluidic chip in the …

Optimization Of Vaccine Supply Chains In Low- And Middle-Income Countries Utilizing Drones, Maximilian Kolter

Graduate Theses and Dissertations

Despite tremendous efforts from governments and humanitarian organizations, millions of children in low- and low-middle-income countries (LICs and LMICs) are still excluded from the benefits of immunization. The vaccine distribution in LICs and LMICs is challenging for several reasons, such as limited cold chain capacities, vaccine wastage, uncertain demand, and lack of access to immunization services. A promising avenue to address these issues is the utilization of drones for vaccine delivery. Drones can fly at high speed on direct paths and could enable on-demand deliveries to mitigate limited storage capacities. Further, their independence of road networks could allow them reaching …