Engineering Commons^™

Microfluidic Flow Focusing Platforms For Optofluidic Droplet Laser Development, Chen Zhang

Electrical Engineering Dissertations - Archive

ABSTRACT: Optofluidic droplet lasers have been developed for different applications in biomedical sciences, such as biosensing, cell tracking, tissue imaging, on-chip spectroscopy, and flow cytometry. Utilizing different generation methods, droplet lasers can be categorized as either static droplet lasers or droplet lasers on the flow. Static droplet lasers, which are supported by a surface or levitated by an external force, can be optically probed for an extended period of time, and thus enabling continuous monitoring of the lasing emission. However, static droplet lasers suffer from low-throughput generation, large size distribution, and poor reproducibility. In contrast, droplet lasers on the flow …

Power Allocation And Massive Mimo Channel Modeling For 5g Wireless Communications, Zhangliang Chen

Electrical Engineering Dissertations - Archive

To meet the demand for wireless communication transmission rate to reach a thousand times of the existing system in 2021, the fifth-generation (5G) mobile communication system was developed. Compared with Long-Term Evolution (LTE), the 5G mobile communication needs to be transmitted in wireless breakthrough innovation in technology to achieve the goal of ten times increase in spectrum efficiency and power efficiency. As a time series analysis tool based on vector autoregression, Granger causal analysis originated in the field of econometrics, and its staged generalized transfer entropy (TE) based on conditional co-information in information theory has been widely used in recent …

Surface Flashover Under Various Surface Conditions, Bradley A. Hannum

Electrical Engineering Theses - Archive

Electrical insulators are critical components used in every high voltage application whether it is operated continuously or in a pulsed mode. Bulk dielectric breakdown and surface flashover must be prevented in all use cases, especially those that occur in polluted environments. Though electrical standards have been written as a guide to prevent insulator surface flashover, such as Underwriters Laboratories (UL) 840, they are not directly applicable to applications where size and weight are critical. UL 840 experimental design is vague, does not consider all environments, and is written primarily with the electric power utilities in mind. The research presented here …

Evolution Prediction Of Hysteresis Behavior Of Sand Under Cyclic Loading, Pingxin Xia, Longtan Shao, Wen Deng, Chao Zeng

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Soil cyclic degradation is a serious issue that should be considered in engineering design and maintenance. The hysteretic response causes strength degradation and excessive settlement of soil structure in engineered and natural geosystems. Hysteresis is essentially the coupling deformation of elastic and plastic components during reloading and unloading processes. Conventional hysteretic models for sand in the elastoplastic framework rely highly on yield surface or potential surface evolution and fall short on complexity and inaccuracy. This study proposes a decoupling method to describe the hysteretic response of sand. In contrast to the conventional elastoplastic approach, this decoupling method can directly decouple …

Implementation Of The Linear Amplitude Sweep Test To Evaluate Fatigue Resistance Of Highly Polymerized Asphalt Binders, Jun Liu, Yizhuang David Wang, Jenny Liu

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Highly polymerized asphalt binders (HPABs) such as PG 64-40 have been increasingly used in cold regions such as Alaska in recent years. However, there are currently considerable data gaps when it comes to the characterizations of the HPABs, especially their fatigue behaviors. The objective of this study is to apply the linear amplitude sweep (LAS) test with the viscoelastic continuum damage (VECD) model to assess the fatigue resistance of HPABs. Three HPABs (PG 52-40, PG 64-40, and PG 52-46) and one unmodified binder (PG 52-28) were used in the study. The fatigue failure during LAS tests on HPABs was defined, …

Comprehensive Evaluation Of Self-Healing Polyampholyte Gel Particles For The Severe Leakoff Control Of Drilling Fluids, Lili Yang, Chunlin Xie, Tian Ao, Kaixiao Cui, Guancheng Jiang, Baojun Bai, Yongwei Zhang, Jun Yang, Xingxing Wang, Weiguo Tian

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Lost circulation has been a serious problem to be solved in many drilling practices during oil, gas and geothermal well drillings. Many materials have been developed and evaluated for the purpose. However, their performance to plug severe leakoff is very limited. Herein, an injectable self-healing hydrogel based on polyampholyte with sulfonated and quaternary ammonium functionalities (P(MPTC-co-NaSS)) was developed and comprehensively evaluated to prevent the severe loss of fluids to formation. By incorporating cation-π (π is for aromatic residues) interaction, the hydrogel shown self-healing property and robustness in severe environment (temperature, salt) by comparison with other hydrogels merely consisting of cation-anion …

Unsupervised Anomaly Detection Via Dual Transformation-Aware Embeddings, Zhipeng Wang, Chunping Hou, Bangbang Ge, Yang Liu, Zhicheng Dong, Zhiqiang Wu

Electrical Engineering Faculty Publications

Unsupervised anomaly detection refers to the discovery of unconventional images that are globally or locally different from the training set. Recently, reconstruction-based anomaly detection methods have made great progress. However, most of the existing methods take reconstructing the original image as the goal of latent feature learning. Due to lack of effective semantic guidance, latent features have intrinsic characteristics which retain redundant details of spatial structure. Such information is too general and cause over-expression problem. To solve this problem, in this paper, dual transformation-aware embeddings are coined which aims to achieve a stable model to learn high-level latent features in …

Implementing The Cms+ Sports Rankings Algorithm In A Javafx Environment, Luke Welch

Industrial Engineering Undergraduate Honors Theses

Every year, sports teams and athletes get cut from championship opportunities because of their rank. While this reality is easier to swallow if a team or athlete is distant from the cut, it is much harder when they are right on the edge. Many times, it leaves fans and athletes wondering, “Why wasn’t I ranked higher? What factors when into the ranking? Are the rankings based on opinion alone?” These are fair questions that deserve an answer. Many times, sports rankings are derived from opinion polls. Other times, they are derived from a combination of opinion polls and measured performance. …

Academic Advising Support Tool: An Optimization Approach, Spencer Loper

Industrial Engineering Undergraduate Honors Theses

More than ever, a college education is necessary to remain competitive in the job market. Therefore, colleges are dedicating numerous resources to ensure student success. Nonetheless, one of the most important factors of student success is proper academic advising. Students at the University of Arkansas and more specifically within the department of Industrial Engineering department are fortunate to have access to fantastic advising. However, given the volume of students, academic advisors do not have the time to talk through the nuance of every student’s long-term academic plan. The department does provide an eight-semester plan; however, students who have deviated from …

Quantitative Non-Destructive Evaluation Of Rebar Corrosion In Concrete, Khadiza Binte Jalal

Civil Engineering Dissertations - Archive

ABSTRACT: Corrosion of rebar is considered the leading cause of deterioration in concrete structures. When steel rust, it occupies larger volume and creates pressure on the concrete, leading to cracking and spalling. As the cross-section is being compromised, the structural capacity of the reinforced concrete structure is reduced. Corrosion is a slow natural electrochemical process that affects the long-term performance. However, sometimes premature catastrophic failure occurs due to corrosion, especially in chloride environments. Moreover, the cost of repair and replacement of deteriorated structures has become a major liability for management agencies. Consequently, it is important to determine the level of …

Selected Interdiction Games With Uncertain, Risk-Averse, And Simultaneous Play Considerations, Di H. Nguyen

All Dissertations

This dissertation examines two network interdiction problems: a shortest-path interdiction problem under uncertainty and a network interdiction problem in a simultaneous game. Both problems happen in two stages over a directed network, and involve a leader and a follower who have opposing interests.

In the first problem, the leader acts first to lengthen a subset of arcs, and a follower acts second to select a shortest path across the network. The cost for a follower’s arc consists of a base cost if the arc is not interdicted, plus an additional cost that is incurred if the arc is interdicted. The …

Reactive Thin Film Polymers And Thin Film Composite Membranes For The Rapid Screening Of Uranium Isotopes, Abenazer W. Darge

All Dissertations

Traditional radiochemistry approaches for the detection of trace-level alpha-emitting radioisotopes in water require lengthy offsite sample preparations and do not lend themselves to rapid quantification. Therefore, a novel platform is needed that combines onsite purification, concentration, and isotopic screening with a fieldable detection system. My dissertation research objective was to develop novel reactive thin polymer films and thin film composite membranes for the selective separation of uranium from environmental water followed by direct isotopic analysis by alpha spectroscopy. Chapter 1 reviews progress made on uranium separation from aqueous matrices and discusses methods used for the determination of isotopic composition.

Chapter …

Control, Decision-Making, And Learning Approaches For Connected And Autonomous Driving Systems With Humans-In-The-Loop, Fangjian Li

All Dissertations

By virtue of vehicular connectivity and automation, the vehicle becomes increasingly intelligent and self-driving capable. However, no matter what automation level the vehicle can achieve, humans will still be in the loop despite their roles. First, considering the manual driving car as a disturbance to the connected and autonomous vehicles (CAVs), a novel string stability is proposed for mixed traffic platoons consisting of both autonomous and manual driving cars to guarantee acceptable motion fluctuation and platoon safety. Furthermore, humans are naturally considered as the rider in the passenger vehicle. A human-centered cooperative adaptive cruise control (CACC) is designed to improve …

Design And Analysis Of Efficient Freight Transportation Networks In A Collaborative Logistics Environment, Vishal Badyal

All Dissertations

The increase in total freight volumes, reducing volume per freight unit, and delivery deadlines have increased the burden on freight transportation systems of today. With the evolution of freight demand trends, there also needs to be an evolution in the freight distribution processes. Today's freight transportation processes have a lot of inefficiencies that could be streamlined, thus preventing concerns like increased operational costs, road congestion, and environmental degradation. Collaborative logistics is one of the approaches where supply chain partners collaborate horizontally or/and vertically to create a centralized network that is more efficient and serves towards a common goal or objective. …

Single Asperity Fretting Corrosion Of Traditional And Additively Manufactured Metallic Biomaterials: Quantitative Analysis From Acetabular Tapers To Micron And Nanometer Scale Tribocorrosion, Annsley Mace

All Dissertations

Mechanically assisted crevice corrosion (MACC) of metallic biomaterials continues to be a significant degradation mode. This is, in part, due to a lack of understanding of fundamental micron- and sub-micron scale mechanisms of metal degradation in biological environments. Metal-metal (or metal-hard) load bearing surfaces of hip arthroplasties are subjected to fretting crevice corrosion (FCC, one form of MACC). Current work in tribocorrosion involves large contact area tests with multiple asperities, with a distribution of load and wear that changes over time. A more systematic and controlled study of the FCC micro- and nanomechanics is needed.

Therefore, the goal of this …

Benchmarking Library Recognition In Tweets, Ting Zhang, Divya Prabha Chandrasekaran, Ferdian Thung, David Lo

Research Collection School Of Computing and Information Systems

Software developers often use social media (such as Twitter) to shareprogramming knowledge such as new tools, sample code snippets,and tips on programming. One of the topics they talk about is thesoftware library. The tweets may contain useful information abouta library. A good understanding of this information, e.g., on thedeveloper’s views regarding a library can be beneficial to weigh thepros and cons of using the library as well as the general sentimentstowards the library. However, it is not trivial to recognize whethera word actually refers to a library or other meanings. For example,a tweet mentioning the word “pandas" may refer to …

Automated Quality Control For In-Situ Water Temperature Sensors, Leah S. Richardson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The identification of data not representative of the target subject for outdoor (in-situ) environmental sensors (bad data) is a topic that has been explored in the past. Many tools (such as data filters and computer models) have succeeded in providing an end user with properly identified incorrect data over 95% of the time. However, with the continuous increase in the use of automated data collection, a simple indication of the bad data may no longer provide the end user with enough information to reduce the amount of time that must be spent for manual quality control. The purpose of this …

Investigating Tourists' Decision Making And Intentions For Outdoor Recreation Participation During Early Covid-19, Prasanna Humagain

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This dissertation aims at discerning tourists’ behaviors and decision making processes for outdoor recreation participation, during the early COVID-19 pandemic. An outdoor recreation trip is defined in this study as “a journey involving at least one overnight stay away from home, and where the purpose is to engage in recreational activities in an outdoor or natural environment.” This dissertation first explores the factors that inhibit tourists’ desires for participating in outdoor recreation trips, the strategies they apply to avoid COVID-19 transmission, and the motivational factors that induce their desires for outdoor recreation participation in the COVID-19 context. The impact of …

Network-Wide Pedestrian And Bicycle Crash Analysis With Statistical And Machine Learning Models In Utah, Md Rafiur Rahman

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Recent trends in crashes indicate a dramatic increase in both the number and share of pedestrian and bicyclist injuries and fatalities nationally and in many states. Crash frequency modeling was undertaken to identify crash prone characteristics of segments and non-signalized intersections and explore possible non-linear associations of explanatory variables with crashes. Crowdsourced “Strava” app data was used for bicycle volume, and pedestrian counts estimated from nearby signalized intersections were used as pedestrian volume. Multiple negative binomial models investigated crashes at different spatial scales to account for different levels of data availability and completeness. The models showed high traffic volume, steeper …

Improved Digital Image Correlation Techniques At High Speed And High Temperature, Lindsey J. Rowley

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In extreme environments, such as hot-fire rocket testing, gathering strain data can be challenging due to temperature constraints. Traditional methods for measuring material deformation such as strain gages, a small device attached to a test specimen, cannot withstand the extreme temperature and tend to burn off. When these situations occur non-contacting methods such as Digital Image Correlation (DIC) are preferable. DIC is an optical method of measuring strains across the material’s entire surface by using a camera to track the deformation of a speckle pattern applied to the surface of a deforming object. When used at temperatures above approximately 500°C, …

Efficient And Secure Resource Allocation In Mobile Edge Computing Enabled Wireless Networks, Qun Wang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

To support emerging applications such as autonomous vehicles and smart homes and to build an intelligent society, the next-generation internet of things (IoT) is calling for up to 50 billion devices connected world wide. Massive devices connection, explosive data circulation, and colossal data processing demand are driving both the industry and academia to explore new solutions.

Uploading this vast amount of data to the cloud center for processing will significantly increase the load on backbone networks and cause relatively long latency to time-sensitive applications. A practical solution is to deploy the computing resource closer to end-users to process the distributed …

Seam Shifted Wake In The Magnus And Non-Magnus Directions, John W. Garrett

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

An experiment was done to look at the effect baseball seams can have on how a pitched baseball moves in flight. Both non-spinning and spinning baseballs were analyzed in this study. Data was taken and analyzed at 60, 90, and 110 MPH to determine the influence of velocity and altitude on the ability of seams to alter the trajectory of a pitched baseball. Additionally, a ball's spin causes movement in a certain direction that is dependent on the spin axis. A second focus of this study was on the effect of baseball seams changing the movement in the same direction …

An Intelligent Passive Islanding Detection And Classification Scheme For A Radial Distribution System, Mohannad Khaleel Subhi Suleiman

Theses

Distributed generation (DG) provides users with a dependable and cost-effective source of electricity. These are directly connected to the distribution system at customer load locations. Integration of DG units into an existing system has significantly high importance due to its innumerable advantages. The high penetration level of distributed generation (DG) provides vast techno-economic and environmental benefits, such as high reliability, reduced total system losses, efficiency, low capital cost, abundant in nature, and low carbon emissions. However, one of the most challenges in microgrids (MG) is the island mode operations of DGs. the effective detection of islanding and rapid DG disconnection …

Desalination Waste Revitalization Using Carbon Capture: Process Optimization Using Machine Learning, Ahmed Mohamed Elsayed

Theses

Over the next five to ten years, desalination will play an ever-important role in our society. Developing nations will look at desalination from the point of water scarcity, while developed nations will consider the perspective of the Water-Energy-Food nexus. With current technology, for every liter of freshwater produced, one and a half liters is thrown away as waste. This body of research proposes to employ chemical precipitation in ammoniated brine solutions, that have reasonably high ionic concentrations. CO2 absorption in Bubble Column Reactors can reduce sodium ions by precipitating NaHCO3. Also, the absorbed CO2 can reduce chloride ions and induce …

Design Of Wideband Decoupling Networks For Mimo Antennas Based On An N-Ary Optimization Algorithm, Min Li, Kwan Lawrence Yeung, Lijun Jiang, Ross Murch

Electrical and Computer Engineering Faculty Research & Creative Works

Techniques for reducing the coupling between antenna elements in multiple-input multiple-output (MIMO) systems are important for achieving the full potential of MIMO. In this article, a general and systematic method is developed to design a wideband decoupling and matching network (DMN) for MIMO antenna arrays. The DMN is formed by grid-like transmission lines interconnected by lumped components, whose reactance can be obtained from an N-ary optimization algorithm. Four design benchmarks are performed for validating decoupling methodology, elaborating on design/implementation procedure, and demonstrating superiority of the proposed method. Results show that the DMN achieves broad isolation bandwidth while occupying a small …

A New Rock Hardness Classification System Based On Portable Dynamic Testing, Sasan Ghorbani, Seyed Hadi Hoseinie, Ebrahim Ghasemi, Taghi Sherizadeh, Christina Wanhainen

Mining Engineering Faculty Research & Creative Works

Hardness is one of the critical physical characteristics of minerals and rocks, which indicates the resistance of the rock to penetration, scratch, or permanent deformation. As a basic concept, rock hardness has a significant role in rock mechanics and geological engineering and is an appropriate diagnostic tool for the classification of minerals and rocks. The main purpose of this study is to guide rock engineers to measure the rock hardness faster, easier, and more accurately using Leeb's dynamic hardness test. Accordingly, this paper presents a new rock hardness classification system based on the Leeb dynamic and portable hardness testing method. …

Preparation Of Concrete Specimen For Internal Sulfate Attack Analysis Using Electron Backscatter Diffraction, R. Sharon Uwanyuze, Lucas Enright, Jiyao Zhang, Stefan Schafföner

Materials Science and Engineering Faculty Research & Creative Works

Concrete cores were obtained from houses in eastern Connecticut, USA, that had varying degrees of crumbling foundations and wall cracking. Electron backscatter diffraction (EBSD) was used simultaneously with energy dispersive X-ray spectroscopy to investigate the degradation of these samples. This combination allowed the precise correlation of elemental composition with mineral crystallography phase mapping. EBSD examination showed the presence of pyrrhotite, pyrite, and marcasite phases in some of the samples, whereas internal sulfate attack (ISA) is triggered by the release of sulfates through the oxidation of such iron sulfides. Secondary expansion products from ISA are associated with foundation cracking, wall bulging, …

Study Of Gas Holdup Distribution In Cylindrical Split Airlift Reactor By Using Gamma-Ray Densitometry (Grd), Abbas J. Sultan, Laith S. Sabri, Hasan Shakir Majdi, Shadha K. Jebur, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

The local gas holdup details and behaviors in the cylindrical split airlift column by using an unconventional gamma-ray densitometry (GRD) measurement in non-invasive manner technique was investigated for the first time in this work for such kind of airlift column. With different gas velocities, 1, 2, and 3 cm/s, at three various axial planes (different levels) in z = 3, 60, and 110 cm were studied for local distribution in radial gas holdup profiles. The distribution in gas–liquid phases (air-water system) in the entire split reactor column, in the rising and descending sides, including their behavior in the upper and …

Process Evaluation And Kinetic Analysis Of 3d-Printed Monoliths Comprised Of Cao And Cr/H-Zsm-5 In Combined Co2 Capture-C2h6 Oxidative Dehydrogenation To C2h4, Khaled Baamran, Shane Lawson, Ali A. Rownaghi, Fateme Rezaei

Chemical and Biochemical Engineering Faculty Research & Creative Works

In this study, dual-function materials (DFMs) comprised of CaO and Cr/H-ZSM-5 were formulated in 3D-printed monolithic structures and investigated in a combined process for capture and utilization of CO₂ in oxidative dehydrogenation of C₂H₆ to C₂H₄ (CO₂-ODHE). Various formulation strategies were employed to fabricate these DFM structures. Two bed designs were considered: i) a layered-bed in which adsorbent (CaO) and catalyst were printed separately and stacked on top of each other, and ii) a single-layer bed where the adsorbent-catalyst materials were 3D-printed into a singular monolith and loaded into the bed …

Integration Of Dynamic Growth Modeling And Hydrodynamics In An Internal-Loop Split Photobioreactor, Laith S. Sabri, Aastha Ojha, Abbas J. Sultan, Muthanna H. Aldahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

In this study, new high-quality experimental data for culturing green microalgae Scenedesmus in tubular and cylindrical split airlift photobioreactors were obtained under different operating conditions. The obtained experimental data of culturing microalgae Scenedesmus in a tubular photobioreactor were used for determining the kinetic parameters of the photosynthetic reaction. On the other hand, the culturing of green microalgae in a split airlift photobioreactor was used to measure the microalgae cell trajectory using an advanced radioactive particle tracking (RPT) technique. The obtained results in terms of kinetic parameters of the photosynthetic reaction and microalgae cell trajectory were integrated for the first time …