Digital Commons Network^™

The Electrification Of The Kitchen: On The Energy Consumption Of Common Electric Cooking Appliances, Hozen Ricchie Rose Asok Rose

Graduate Theses and Dissertations

In developed countries, electricity has been gaining popularity as a source of energy for meal preparation. Utilizing electricity produced from renewable resources along with efficient electrical cooking appliances could result in sustainable clean cooking. The first objective of this research was to study the efficiency of common electrical cooking appliances—namely induction, resistance plate, resistance coil, infrared, and electric pot— by the water boiling test and the simmering test. The induction and electric pot were observed as the most efficient devices for the water boiling test. For simmering, which mimics many cooking processes, the electric pot and resistance coil were the …

Component Damage Source Identification For Critical Infrastructure Systems, Nathan Davis

Graduate Theses and Dissertations

Cyber-Physical Systems (CPS) are becoming increasingly prevalent for both Critical Infrastructure and the Industry 4.0 initiative. Bad values within components of the software portion of CPS, or the computer systems, have the potential to cause major damage if left unchecked, and so detection and locating of where these occur is vital. We further define features of these computer systems and create a use-based system topology. We then introduce a function to monitor system integrity and the presence of bad values as well as an algorithm to locate them. We then show an improved version, taking advantage of several system properties …

Sigesn Light-Emitting Devices: From Optical To Electrical Injection, Yiyin Zhou

Graduate Theses and Dissertations

Si photonics is a fast-developing technology that impacts many applications such as data centers, 5G, Lidar, and biological/chemical sensing. One of the merits of Si photonics is to integrate electronic and photonic components on a single chip to form a complex functional system that features compact, low-cost, high-performance, and reliability. Among all building blocks, the monolithic integration of lasers on Si encountered substantial challenges. Si and Ge, conventional epitaxial material on Si, are incompetent for light emission due to the indirect bandgap. The current solution compromises the hybrid integration of III-V lasers, which requires growing on separate smaller size substrates …

Material Detection With Thermal Imaging And Computer Vision: Potentials And Limitations, Jared Poe

Graduate Theses and Dissertations

The goal of my masters thesis research is to develop an affordable and mobile infraredbased environmental sensoring system for the control of a servo motor based on material identification. While this sensing could be oriented towards different applications, my thesis is particularly interested in material detection due to the wide range of possible applications in mechanical engineering. Material detection using a thermal mobile camera could be used in manufacturing, recycling or autonomous robotics. For my research, the application that will be focused on is using this material detection to control a servo motor by identifying and sending control inputs based …

Assimilation Of Seasonal Moisture Variability In North America And Asia For The Last Millennium, Chang Liu

Graduate Theses and Dissertations

The seasonal tree-ring chronologies that recorded discrete moisture signal for warm and cool season have been used to reconstruct the North America Seasonal Precipitation Atlas (NASPA) by the point-by-point regression method, and the results indicated that they can fairly reproduce the seasonal precipitation variability in the past. Compared with reconstructions using only paleoclimate proxy data, the paleoclimate data assimilation (PDA) considers both proxy data and climate model output, so the PDA reconstructions are consistent with both the climate signals reflected by the proxy data and the physical mechanisms represented by climate models. Based on the tree rings with discrete seasonal …

2+2=Cake: A Book Of Conversations About Possibilities In Business And Art, Elizabeth Ann Alspach

Graduate Theses and Dissertations

2+2=CAKE is a toolkit for people interested in creating their own economic container to support their livelihood. Calling upon the entrepreneurial experience of artists and creatives who founded or run organizations, the book and accompanying workbook and motivational posters serve as an incubator, buoy, and affirming resource for those looking to build the economic container in which they make their livelihood.

Computational Frameworks For Multi-Robot Cooperative 3d Printing And Planning, Laxmi Prasad Poudel

Graduate Theses and Dissertations

This dissertation proposes a novel cooperative 3D printing (C3DP) approach for multi-robot additive manufacturing (AM) and presents scheduling and planning strategies that enable multi-robot cooperation in the manufacturing environment. C3DP is the first step towards achieving the overarching goal of swarm manufacturing (SM). SM is a paradigm for distributed manufacturing that envisions networks of micro-factories, each of which employs thousands of mobile robots that can manufacture different products on demand. SM breaks down the complicated supply chain used to deliver a product from a large production facility from one part of the world to another. Instead, it establishes a network …

Phase-Field Modeling Of The Polymer Membrane Formation Process For Micro- And Ultra-Filtration, Michael Rosario Cervellere

Graduate Theses and Dissertations

Porous polymer membrane filters are widely used in separation and filtration process. Micro- and ultra-filtration membranes are commonly used in biopharmaceutical applications such as filtering viruses and separating proteins from a carrier solution. The formation of these membrane filters via phase inversion is a complex and interconnected process where varying casting conditions can have a wide variety of effects on the final membrane morphol- ogy. Tailoring membrane filters for specific performance characteristics is a tedious and time consuming process. The time and length scales of membrane formation make it extremely difficult to experimentally observe membrane formation. Modeling the membrane formation …

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 …

Evaluating The Efficiency Of Markov Chain Monte Carlo Algorithms, Thuy Scanlon

Graduate Theses and Dissertations

Markov chain Monte Carlo (MCMC) is a simulation technique that produces a Markov chain designed to converge to a stationary distribution. In Bayesian statistics, MCMC is used to obtain samples from a posterior distribution for inference. To ensure the accuracy of estimates using MCMC samples, the convergence to the stationary distribution of an MCMC algorithm has to be checked. As computation time is a resource, optimizing the efficiency of an MCMC algorithm in terms of effective sample size (ESS) per time unit is an important goal for statisticians. In this paper, we use simulation studies to demonstrate how the Gibbs …

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 …

The Application Of Complex Systems Science To Political Philosophy, Benjamin Nicholas House

Graduate Theses and Dissertations

Although complex systems science is relevant to problems of political philosophy, the intersection of these two disciplines has not been studied in depth. Complex systems are made up of multiple interdependent parts whose interactions create emergent properties. This interdependence makes these systems “fat-tailed”: low-probability events can have a major impact on the system. Complex systems engineers have formulated a series of rules of thumb for approximating an “evolutionary” environment. Contemporary human civilization is a complex system; because of this, governments need to become adaptable and approximate the evolutionary environment by fostering policy innovation while at the same time promoting mechanisms …

Modeling The Lafourche Delta Network In The Mississippi Delta Complex, Byong-Suk Chun

Graduate Theses and Dissertations

The distributary channel network morphology on deltas is important for the delta evolution study because channels are the primary conduit for carrying and distributing water, sediment, and nutrients to the coast. Numerical models of river deltas and their channels have improved remarkably over the past two decades. However, the long-term (millennial scale) simulation of real delta systems remains rare. Here, we attempt to reconstruct the Lafourche Delta channel network, active 1600-600 years before present, with a simple numerical model (Moving Boundary Model for Distributary Network, MB_DCN). The model was run for 9 possible paleo basin boundaries and 6 water discharge …

Modeling And Measuring Water Level Fluctuations In The Greenland Ice Sheet: How Moulin Life Cycle And Shape Can Inform Us On The Subglacial Drainage System., Celia Trunz

Graduate Theses and Dissertations

In the ablation zone of land terminating sectors of the Greenland Ice Sheet (GrIS), water pressures at the bed control ice motion variability on diurnal and seasonal timescales. During the melt season, large volumes of surface meltwater access the ice-bed interface through moulins.Moulins are large vertical shafts that connect the supraglacial and subglacial drainage systems. Moulins form when a crevasse intersects a surface meltwater source that can drive hydrofracture to the bed of the ice sheet. Upon reaching the bed, meltwater can establish and sustain an efficient, channelized drainage system. Due to the technical impossibility of physically exploring underwater passages …

Statistical Modeling For High-Dimensional Compositional Data With Applications To The Human Microbiome, Thy Dao

Graduate Theses and Dissertations

Compositional data refer to the data that lie on a simplex, which are common in many scientific domains such as genomics, geology, and economics. As the components in a composition must sum to one, traditional tests based on unconstrained data become inappropriate, and new statistical methods are needed to analyze this special type of data. This dissertation is motivated by some statistical problems arising in the analysis of compositional data. In particular, we focus on the high-dimensional and over-dispersed setting, where the dimensionality of compositions is greater than the sample size and the dispersion parameter is moderate or large. In …

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 …

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 …

Discipline Disproportionality Of Black Students With Disabilities: Principals' Perspectives, Wanda L. Van Dyke

Graduate Theses and Dissertations

The purpose of this study is to examine the problem of practice found in discipline disproportionality of Black students with disabilities in an urban school district with a majority Black student and teacher population. Through personal interviews with building level administrators, data was gained to determine common themes that impact discipline disproportionality of Black students with disabilities. A qualitative inquiry approach, in the form of a case study was used to determine principals’ perspectives about factors that may impact discipline disproportionality. Student disciplinary records were examined to verify disproportionality and investigate patterns and categories related to students with and without …

Host-Parasite Interactions Within Food Webs, Adam Zvanut Hasik

Graduate Theses and Dissertations

Parasitism is one of the most common life history strategies employed in nature, yet the effects of parasites are often thought to be minimal, and the vast majority of studies fail to consider parasites and their effects on host organisms. This is likely a problem, as the magnitude of parasite-mediated effects on their hosts can be quite large. Additionally, the effects of parasites are known to extend beyond the host to affect other species interactions. I used a series of approaches to gain a more integral understanding of host-parasite interactions by studying (1) the effects of parasites on biotic interactions …

Of Biodiversity, Boundaries, And Distribution: The Myxomycetes Of The Philippines And Beyond, Sittie Aisha Bustamante Macabago

Graduate Theses and Dissertations

This dissertation contains a compilation of independently performed studies primarily focusing on the myxomycetes (plasmodial slime molds) from the Philippines and integrating local and worldwide data to demonstrate regional and global trends. The major themes include the following: (I) a review of the diverse group of spore-producing amoeboid protists, including the myxomycetes; (II-IV) diversity assessments in three different groups of islands in the Philippine archipelago; (V) mapping the myxomycetes found in the Philippines for databasing and analyzing the geocoded data; (VI) a study on regional boundaries, including the Philippines, using myxomycete species composition; and, (VII) creating a global species distribution …

An Experimental Study Of Evaporites On Titan: Implications For Lake Composition And Future Missions, Ellen Czaplinski

Graduate Theses and Dissertations

Titan is the only other planetary body in the solar system with liquid on the surface. With a surface temperature and pressure of 89 – 94 K and 1.5 bar (N2), respectively, Titan’s lakes are comprised of liquid hydrocarbons, predominantly methane and ethane. Over time, Titan’s lakes may evaporate, leaving behind residual deposits (evaporites). The evaporation processes and composition of the evaporites is poorly understood. I address these outstanding questions by experimentally investigating the physical and spectral properties of evaporites at Titan surface conditions using an experimental chamber.

Chapter 1 addresses the formation of ethylene evaporites. Ethylene evaporites form more …

Microfabrication And Electrochemical Characterization Of A Novel Su-8 Probe With An Array Of Individually Addressable Electrodes Suitable For Redox Cycling Experiments In Ultra-Small Volumes, Mahsa Lotfi Marchoubeh

Graduate Theses and Dissertations

Redox cycling is an electrochemical technique that utilizes closely spaced generator and collector electrodes to cycle reversible redox species between their oxidative states. With advantages in signal amplification, selectivity of species based on their electrochemical reaction mechanism, and limited or no background subtraction, this technique is well suited for selective detection of important electrochemically active molecules such as dopamine at basal or slowly changing levels.

Miniaturized medical devices have become an area of great interest for measurement of chemicals in limited volumes with low concentrations or in sensitive tissues. A probe on a polymeric SU-8 substrate with suitable dimensions and …

Impact Of Covid-19 On The Severe Acute Malnutrition Admissions Among Children Under 5 Years Of Age Seeking Nutrition Services In Afghanistan, Sahar Sayedy

Graduate Theses and Dissertations

The purpose of the study was to assess the impact of COVID-19 on the number of admissions of severe acute malnutrition among children under 5 years of age seeking nutrition services in Afghanistan especially in the provinces where the prevalence of COVID-19 was high, for the period of February – September 2020. The study used comparison and analysis of secondary datasets of the Integrated Management of Acute Malnutrition – a national program for detection and management of moderate and severe acute malnutrition in the country.

This study analyzed the association between COVID-19 cases and severe acute malnutrition (SAM) admissions of …

Gradient Estimates And The Fundamental Solution For Higher-Order Elliptic Systems With Lower-Order Terms, Michael J. Duffy Jr.

Graduate Theses and Dissertations

Here we generalize the higher-order divergence-form elliptic differential equations studied by Barton in [4] by the inclusion of certain lower-order terms. The methods used here compare to those used in [4], with the addition of further Sobolev-type estimates to handle included lower-order terms. In section 3 we derive a Caccioppoli inequality in which we bound the L2 norm of the mth order gradient, in terms of the L2 norm of the solution. In section 5 we adapt some of the ideas from [9] to derive Lp bounds on gradients of solutions as a substitute for a reverse Holder inequality. Finally …

Privacy-Preserving Cloud-Assisted Data Analytics, Wei Bao

Graduate Theses and Dissertations

Nowadays industries are collecting a massive and exponentially growing amount of data that can be utilized to extract useful insights for improving various aspects of our life. Data analytics (e.g., via the use of machine learning) has been extensively applied to make important decisions in various real world applications. However, it is challenging for resource-limited clients to analyze their data in an efficient way when its scale is large. Additionally, the data resources are increasingly distributed among different owners. Nonetheless, users' data may contain private information that needs to be protected.

Cloud computing has become more and more popular in …

Structural And Electronic Properties Of Few-Layer Monochalcogenides, Brandon Joel Miller

Graduate Theses and Dissertations

This work discusses a new class of materials with novel properties that have only recently begun being studied. These materials are two-dimensional group IV-VI monochalcogenides, so named because they are formed from group IV (carbon group) and group VI (chalcogens) elements. These materials display several interesting physical properties such as ferroelasticity and ferroelectricity, and the contents within Chapters Two, Three, and Four concern a collaborative effort between theory and experiment between our group at the University of Arkansas and Dr. Kai Chang at the Max Planck Institute of Microstructure Physics in Halle, Germany in studying these properties. This thesis is …

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 …

Nutrient Sources, Loads And Trends Vary Spatially And Temporally Within The Poteau River Watershed And Lake Wister, Oklahoma, Abbie Lasater

Graduate Theses and Dissertations

Excess inputs of nutrients and sediments jeopardize drinking water sources, aquatic life habitats, and aesthetic quality of freshwater resources for recreation. The purpose of this dissertation was to analyze long-term water quality trends and loads in the Upper Poteau River Watershed (UPRW) and the Lake Wister Watershed (LWW), and analyze internal phosphorus (P) loads in Lake Wister, Oklahoma. Additionally, this dissertation sought to review the literature for methods of prioritizing subwatersheds for watershed management using watershed models, implement a cost efficient method to remotely monitor streamflow and estimate constituent loads in small-scale watersheds, and finally, to validate the Soil Water …

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, …

Enabling The “Easy Button” For Broad, Parallel Optimization Of Functions Evaluated By Simulation, Andrew Gibson

Graduate Theses and Dissertations

Java Optimization by Simulation (JOBS) is presented: an open-source, object-oriented Java library designed to enable the study, research, and use of optimization for models evaluated by simulation. JOBS includes several novel design features that make it easy for a simulation modeler, without extensive expertise in optimization or parallel computation, to define an optimization model with deterministic and/or stochastic constraints, choose one or more metaheuristics to solve it and run, using massively parallel function evaluation to reduce wall-clock times.

JOBS is supported by a new language independent, application programming interface (API) for remote simulation model evaluation and a serverless computing environment …