Digital Commons Network^™

In Band Full Duplex For Wireless Communication, A Medium Access Control Perspective, Yazeed Alkhrijah

Electrical Engineering Theses and Dissertations

In-band full duplex (IBFD) for wireless communication is defined as the ability of a node to send and receive data simultaneously by using the same frequency band. IBFD has the potential to double the spectral efficiency of wireless networks. In addition, IBFD improves security by mystifying any eavesdropper with multiple transmitted signals in a single frequency. Also, IBFD reduces the end-to-end transmission delay and solves the hidden terminal and exposed terminal problems. However, IBFD suffers from self-interference. Canceling self-interference (SI) is the main challenge in enabling IBFD. Another challenge for IBFD is to manage access to the network. IEEE802.11 are …

Compact Formulation Of Multicommodity Network Flows With Applications To The Backhaul Profit Maximization Problem And Fixed Charge Network Flow Problem, Yulan Bai

Operations Research and Engineering Management Theses and Dissertations

The triples formulation is a compact formulation of multicommodity network flow problems that provides a different representation of flow than the traditional and widely used node-arc and arc-path approaches. In the literature, the triples formulation has been applied successfully to the maximum concurrent flow problem and to a network optimization problem with piecewise linear convex costs. This dissertation applies the triples formulation to the backhaul profit maximization problem (BPMP) and the fixed charge network flow problem (FCNF). It is shown that the triples representation of multicommodity flow significantly reduces the number of variables and constraints in the mixed integer programming …

2022 Fall Commencement Program For The University Of Arkansas At Little Rock., University Of Arkansas At Little Rock. Records And Registration

Commencement Programs

No abstract provided.

Protection And Control Of Electric Power Grid Under High Penetration Of Ders, Binod Prasad Poudel

Electrical and Computer Engineering ETDs

Modernizing power grids with communication-based technologies has introduced new challenges to the operation of the grid, especially when the communication network experiences failure or data is corrupted during the transfer. This issue is studied in this dissertation from the control and protection perspective. First, the cyber attack detection and mitigation of distributed control of microgrids is addressed when the distributed energy resources (DER) are exposed to false data injection attacks. A cyber-threat detection technique is proposed based on Kullback-Liebler divergence-based criterion. This criterion with a threshold can detect the misbehavior of a compromised DER control unit and, consequently, calculates the …

Energy Dissipation In A Sand Damper Under Cyclic Loading, Ehab Sabi

Civil and Environmental Engineering Theses and Dissertations

Various seismic and wind engineering designs and retrofit strategies have been in development to meet structures' proper and safe operation during earthquake and wind excitation. One such method is the addition of fluid and particle dampers, such as sand dampers, in an effort to reduce excessive and dangerous displacements of structures. The present study implements the discrete element method (DEM) to assess the performance of a pressurized sand damper (PSD) and characterize the dissipated energy under cyclic loading. The idea of a PSD is to exploit the increase in shearing resistance of sand under external pressure and the associated ability …

Leveraging Crowdsourced Navigation Data In Roadway Pluvial Flash Flood Prediction, Arefeh Safaei-Moghadam

Civil and Environmental Engineering Theses and Dissertations

This dissertation develops and tests a new data-driven framework for short-term roadway pluvial flash flood (PFF) risk estimation at the scale of road segments using crowdsourced navigation data and a simplified physics-based PFF model. Pluvial flash flooding (PFF) is defined as localized floods caused by an overwhelmed natural or engineered drainage system. This study develops a data curation and computational framework for data collection, preprocessing, and modeling to estimate the risk of PFF at road-segment scales. A hybrid approach is also developed that couples a statistical model and a simplified physics-based simulation model in a machine learning (ML) model to …

Silicon Photonics Trench Coupler Design, Foundry Fabrication, And Characterization, Evan Stewart

Mechanical Engineering Research Theses and Dissertations

In this thesis, compact 2-by-2 and 4-by-4 trench couplers in the silicon photonics material system have been designed, fabricated, and tested. The couplers operate on the principle of frustrated total internal reflection, allowing a footprint significantly smaller than industry standard y-couplers. As photonic integration evolves, larger scales of integration will benefit from such reduction in component size. The couplers were manufactured at the AIM silicon photonics foundry using processes available to multi-project wafer runs. The characterization of the trench couplers involves novel use of U-turns to provide efficiency estimates. For this generation of trench coupler, the experimental loss is measured …

Experimental And Numerical Studies On Laser Hot Wire Cladding By A High-Power Direct Diode Laser, Mingpu Yao

Mechanical Engineering Research Theses and Dissertations

Laser hot wire cladding is an advanced surface modification technology. It has been extensively growing during the last decades due to its high deposition rate, good metallurgical bonding between the substrate and clad layer, low dilution ratio, and small heat-affected zone. There are many kinds of lasers widely used in the laser cladding process. The high-power direct diode laser is widely welcomed because of its high energy efficiency, high electro-optic conversion efficiency, low cost, and high reliability. A rectangular-shaped direct diode laser beam combined with hot wire feeding can achieve a lower dilution depth with a uniform fusion line compared …

Novel Locomotion Methods In Magnetic Actuation And Pipe Inspection, Adam Cox

Mechanical Engineering Research Theses and Dissertations

There is much room for improvement in tube network inspections of jet aircraft. Often, these inspections are incomplete and inconsistent. In this paper, we develop a Modular Robotic Inspection System (MoRIS) for jet aircraft tube networks and a corresponding kinematic model. MoRIS consists of a Base Station for user control and communication, and robotic Vertebrae for accessing and inspecting the network. The presented and tested design of MoRIS can travel up to 9 feet in a tube network. The Vertebrae can navigate in all orientations, including smooth vertical tubes. The design is optimized for nominal 1.5" outside diameter tubes. We …

Development Of A Muc1 Cancer Immunotherapy Using Complement Targeted Liposomes And Organoplatinum (Iv) Complex As An Effective Anticancer Drug, Ameneh Arabi

Chemistry and Biochemistry

The development of therapeutic and preventive cancer vaccines has been on the rise in the past decade. Extensive tumor antigen libraries supply researchers with a wide variety of targets for developing cancer vaccines. Cancer vaccines aim to induce tumor regression, eradicate tumors and establish lasting antitumor memory, while avoiding adverse reactions. However, achieving this goal is hampered by the challenges of finding tumor antigens to incite an effective immune response and creating an efficient delivery system to deliver the antigen to target cells. In this thesis, we discuss how to integrate Toll Like Receptor (TLR) agonists with a MUC1 cancer …

Potential Benefits Of The Campus Outdoor Built Environment On Student Stress, Leading To Improved Retention, Kevin Dilliard

Graduate Liberal Studies Theses and Dissertations

University landscape managers often ask themselves, are they making a difference? Since what they do is not a revenue-generating department, how can they validate their true worth beyond making the campus beautiful, which is excellent, but what added value do they bring? As is common practice, when economic times get tough, the landscape department budget is one of the first to be cut, but is that the wisest thing to do? This research was intended to explore the concept that the services landscape managers provide have a return on investment by providing an environment in which students can thrive and …

Ud In The News Dec. 10-17, University Of Dayton

News Releases

Diverse: Issues In Higher Education, Commonweal and Sinclair Broadcasting's The National Desk highlighted UD programs and expertise. Regional and local media featured a new program for first-generation students and classes working for the common good.

Understanding Your Cultural Identities: A Self-Study Of The Impact Of One’S Cultural Identities On Interpreting Interactions, Shelby L.W. Sammartino

Education Doctorate Dissertations

There is a disproportionality of students of color receiving office referrals for disrespect and defiance because disrespect and defiance are subjective in interpretation by teachers in the classroom. This self-study aims for the researcher to identify and understand the construction of their cultural identities, so they can determine how their cultural identities impact their interpretation of interactions with students concerning disrespect and defiance, how their cultural identities impact their choice of behavior management technique in interactions concerning disrespect and defiance, and how their cultural identities impact their discipline decisions in interactions concerning disrespect and defiance. The data to determine the …

Architects Of Abundance: Indigenous Regenerative Food And Land Management Systems And The Excavation Of Hidden History, Lyla June Johnston

Indigenous Studies

Pre-Columbian and contemporary Indigenous Nations of North and South America (hereafter referred to as Turtle Island and Abya Yala) have managed ecosystems extensively to produce prolific and predictable food systems for themselves and non-humans, whom they often view as relatives. The elements of earth, water, fire, and air are explored to analyze Indigenous soil management, Indigenous aquaculture, Indigenous pyrogenic land management, and Indigenous oral histories, respectively. First, a review of four Indigenous societies and their soil management techniques revealed that none of these systems require outside fertilizer or irrigation to sustain ecocentric food systems on millennial scales. Second, a comparative …

Controllability Of Non-Self-Adjoint Systems Of Partial Differential Equations, Jeff Park

Mathematics and Statistics

In this dissertation, we first consider the problem of exact controllability of a system of N one-dimensional coupled wave equations when the control is exerted on a part of the boundary by means of one control. We provide a Kalman condition (necessary and sufficient) and give a description of the attainable set. The second problem we consider is the inverse problem for the vector Schrödinger equation on the interval with a non-self-adjoint matrix potential. In doing so, we prove controllability of the system and develop a method to recover spectral data from the system. Then, we solve the inverse problem …

Control And Inverse Problems For The Wave Equation On Metric Graphs, Yuanyuan Zhao

Mathematics and Statistics

This thesis focuses on control and inverse problems for the wave equation on finite metric graphs. The first part deals with the control problem for the wave equation on tree graphs. We propose new constructive algorithms for solving initial boundary value problems on general graphs and boundary control problems on tree graphs. We demonstrate that the wave equation on a tree is exactly controllable if and only if controls are applied at all or all but one of the boundary vertices. We find the minimal controllability time and prove that our result is optimal in the general case. The second …

Formation And Interrogation Of A Modeling Excel Database For Sorbent Preconcentrate With Gc/Ms, Lisa Caravello

Chemical and Biological Engineering ETDs

Volatile organic compounds (VOCs) are of great interest and the subject of much research, as they can be used in various applications. Preconcentrating this class of analytes is necessary as they can be elusive with simple sampling techniques. VOCs are often captured using sorbents in thermal desorption tubes as preconcentrates prior to analysis, commonly gas chromatography mass spectroscopy (GCMS). There are gaps in knowledge in behavior of materials used as sorbents i.e., if they will retain an analyte of interest appropriately. In this research I seek to eliminate speculation and unknown variables of analyte and sorbent combinations by creating a …

Species Distribution Modeling Of Northern Sea Otters (Enhydra Lutris Kenyoni) In A Data-Limited Ecosystem, Elizabeth L. Hasan

Marine Biology

Species distribution models are used to map and predict geographic distributions of animals based on environmental covariates. However, species distribution models often require high resolution habitat data and time-series data on animal locations. In data-limited regions with little animal survey data or habitat information, modeling is more challenging and often ignores important environmental attributes. For sea otters (Enhydra lutris), a federally protected keystone species with variable population trends across their range, predictive modeling of distributions has been successfully conducted in areas with an abundance of sea otter and habitat data. Here, we used open-access data across a single time step …

Acute Toxicity Of Copper To Three Species Of Pacific Salmon In Water With Low Hardness And Low Dissolved Organic Carbon, Drew E. Porter

Marine Biology

Despite a history of investigation, the toxicity of copper (Cu) to fishes remains difficult to predict due to the complex influential effects of water chemistry. Water hardness and dissolved organic carbon (DOC) concentrations can vary significantly within a watershed and also attenuate the toxicity of Cu to fishes. To account for location-specific water chemistry and predict Cu toxicity to aquatic organisms the United States Environmental Protection Agency (USEPA) endorses use of the biotic ligand model (BLM). Though the BLM has proven useful in many instances, it has performed inaccurately for waters low in hardness and DOC; this has raised questions …

Exploring The North American Arctic Benthos: Community Structure And Oil Degradation Potential Of Sediment Bacteria And Archaea, Alexis M. Walker

Marine Biology

The Chukchi and Beaufort seas benthic habitats are home to a multitude of ecologically and commercially important organisms that are subject to ongoing environmental changes, including the impacts of climate change and increased exposure to contaminants. Benthic bacteria and archaea can be considered biogeochemical engineers. They play a major role in organic matter (OM) degradation and nutrient cycling and their community structure can reflect changes in environmental conditions such as OM composition and quantity, nutrient availability, redox conditions, and natural/anthropogenic contaminants (e.g. petroleum hydrocarbons). Yet, sediment microbial communities have rarely been examined in these marginal seas of North American Arctic. …

Distribution Network Planning And Operation With Autonomous Agents, Abdulraheem Hassan Alobaidi

Electrical Engineering Theses and Dissertations

With the restructured power system, different system operators and private investors are responsible for operating and maintaining the electricity networks. Moreover, with incentives for a clean environment and reducing the reliance on fossil fuel generation, future distribution networks adopt a considerable penetration of renewable energy sources. However, the uncertainty of renewable energy sources poses operational challenges in distribution networks. This thesis addresses the planning and operation of the distribution network with autonomous agents under uncertainty. First, a decentralized energy management system for unbalanced networked microgrids is developed. The energy management schemes in microgrids enhance the utilization of renewable energy resources …

Orbital Angular Momentum Orthogonality-Based Crosstalk Reduction: Theory And Experiment, Unaiza Tariq

Electrical Engineering Theses and Dissertations

Full duplex communication systems allow a single channel to be used for simultaneous two-way communication, increasing spectral efficiency. However, full duplex communication systems suffer from the issue of self-interference between local transmitter and receiver antennas. Analog subtraction and signal processing methods have previously been used to reduce this problem. This dissertation proposes the use of waves carrying orbital angular momentum (OAM) to mitigate the problem of self-interference by offering a means of additional isolation between local antennas.

Orbital angular momentum has been widely studied both in the photonics and radio domain. The theoretically infinite orthogonal states of an OAM signal …

Distribution Network Operation With Solar Photovoltaic And Energy Storage Technology, Mohammad Ramin Feizi

Electrical Engineering Theses and Dissertations

Among distributed energy resources, solar photovoltaic (PV) generation has the largest penetration in the distribution networks. Serving electric vehicles (EV) with renewable resource generation would further reduce the carbon footprint of the energy supply chain for electric vehicles. However, the integration of solar PV and EVs in the unbalanced distribution network introduces several challenges including voltage fluctuations, voltage imbalances, reverse power flow, and protection devices’ malfunctions. The uncertainties associated with solar PV integration and electric vehicles operation require significant effort to develop accurate optimization methodologies in the unbalanced distribution systems operation. In this thesis, in order to cope with the …

Development And Application Of A Design Flow For Photonic Integrated Circuits, Ifeanyi Achu

Electrical Engineering Theses and Dissertations

Silicon photonics allows for the fabrication of many optical elements on a single photonic integrated circuit (PIC). By taking advantage of the established foundry technology used in the CMOS and silicon’s high refractive index, high feature density manufacturing can be achieved in mass quantities. In CMOS fabrication, from conception of an electronic circuit to testing, the process of designing an electronic circuit is dictated by a design flow which has been developed over the course of decades. This flow includes circuit level design and simulation, layout of the circuit, layout and verification of the chip, fabrication, packaging, and testing. Given …

An Investigation Of The Role Of System Effectiveness In The Acquisition And Sustainment Of U.S. Defense Systems: 1958 To 2022, John Green

Operations Research and Engineering Management Theses and Dissertations

This dissertation investigates the role of the system effectiveness methodology in acquiring and sustaining U.S. military weapons systems from 1958 to 2021. The period of interest has seen numerous changes in both the acquisition process and the application of system effectiveness to acquisition and sustainment. Several of the changes were disruptive, including shifting acquisition and sustainment to a commercial paradigm and completely overhauling the approach to acquiring new systems. The method of inquiry integrated three qualitative methods–structured literature review, grounded theory analysis, and historiography–into an innovative approach for investigating the changes to system effectiveness. The database for the investigation was …

The Challenge Of Change, Eric F. Spina

President's Blog: From the Heart

"Some people are book-smart, but lack empathy, kindness and mercy. You cannot go about transforming the world — which is ultimately your assignment when you leave today — without both," President Eric Spina told the Class of 2022 at winter commencement. "As Flyers, you’re called to use your minds and hearts to work across disciplines and differences to make the kind of profound change the world needs."

Surprise Gift Benefits Two Um Programs, Bill Dabney

University of Mississippi News

No abstract provided.

Void-Semiconductor Gaas Photonic Crystal Surface-Emitting Lasers By Epitaxial Regrowth And Single-Epitaxy Methods, Kevin James Reilly

Nanoscience and Microsystems ETDs

Monolithic semiconductor lasers including edge-emitting lasers (EELs) and vertical-cavity surface-emitting lasers (VCSELs) fail to realize simultaneous achievement of both high-power high-quality beams due to intrinsic limitations of their resonant cavity. Photonic crystal surface emitting lasers (PCSELs) address these structural limitations through employment of a two-dimensional photonic crystal (PC) cavity that creates feedback at a single wavelength for laterally scalable devices. This function of the PC allows PCSELs to power scale with area while maintaining single-mode emission required for diffraction-limited beams. In this way, PCSELs fulfill an industry demand for high-power high-quality lasing from a single chip.

Early PCSELs were fabricated …

Seaweeds Across Ecosystem Boundaries: From Habitat Formation To Harvest Implications, Brian P. Ulaski

Marine Biology

This dissertation broadly investigates the response of wild stock seaweeds to harvesting, and their role as biogenic habitat formers when cast ashore. Seaweeds are important primary producers and foundation species that maintain their functional roles across coastal ecosystem boundaries. Climate-driven loss of seaweed biomass, including that of kelp forests, is exacerbated by other human-related activities that directly impact their persistence, such as overharvesting. Attached rockweeds and kelps are commonly harvested for food, while diverse assemblages of beach-cast seaweed wrack are collected for fertilizer. The importance of wrack habitat in Alaska has not been extensively explored, especially in regions where there …

A Design And Implementation Of A Low-Power Embedded System For Data Collection In An Airborne Sea Ice Thickness Observing System, Thimira Sanuka Asurapmudalige

Engineering

The Long-Range Airborne Snow and Sea Ice Thickness Observing System (LASSITOS) is an airborne electromagnetic (AEM) system, currently under development, which uses a customdesigned instrument mounted on an Unmanned Aerial System (UAS) to measure Arctic sea ice and snow thickness. This project requires specialized instruments that are both low-power and lightweight. This thesis describes a design and implementation of a prototype data logging system based on an ultra-low power microcontroller, for the LASSITOS instrument. Three 32-bit Analog-toDigital Converter (ADC) integrated circuits (IC) are used to sample and convert the receiving EM signal at a rate of 19200 SPS. The system …