Engineering Commons^™

Achieving Causal Fairness In Recommendation, Wen Huang

Graduate Theses and Dissertations

Recommender systems provide personalized services for users seeking information and play an increasingly important role in online applications. While most research papers focus on inventing machine learning algorithms to fit user behavior data and maximizing predictive performance in recommendation, it is also very important to develop fairness-aware machine learning algorithms such that the decisions made by them are not only accurate but also meet desired fairness requirements. In personalized recommendation, although there are many works focusing on fairness and discrimination, how to achieve user-side fairness in bandit recommendation from a causal perspective still remains a challenging task. Besides, the deployed …

Understanding The Bond Strength Of Bcsa Cement Repair Concrete To Portland Cement Concrete, Brenden Simmons

Civil Engineering Undergraduate Honors Theses

Concrete structures deteriorate over time, and there is an increasing demand for quick repair solutions. Belitic calcium sulfoaluminate (BCSA) cement, a type of rapid setting cement, is thought to be a more sustainable and convenient alternative to portland cement in repair concrete applications. Indicated by the name, rapid setting concrete can set up quicker than traditional portland cement concrete. Because of this, there has been a lot of research about the properties of rapid setting concrete mixes. One of the most popular topics is the strength of the concrete itself. However, there is a need for more research to understand …

Investigation Of Micp Based 3d Printed Soils, Kathleen Weston

Civil Engineering Undergraduate Honors Theses

The advent of additive manufacturing, often called 3D printing, offers potential for new and more sustainable soil improvement techniques. Previous research at the University of Arkansas has examined Microbially Induced Calcite Precipitation (MICP) as a possible binder option that is a more sustainable alternative to Portland cement and can be used in remote areas where Portland cement may not be available. The objective of this research is to develop an increased understanding of the potential of utilizing MICP as a spray binding technique for applications in 3D printed soils. The specific goals of this research include: examining the effectiveness of …

Impacts Of Diagonal Crosswalk Misuse, Elizabeth Francis

Civil Engineering Undergraduate Honors Theses

A diagonal crosswalk paired with an all-red phase traffic signal is an effective approach to manage intersections with high pedestrian volume. This allows pedestrians to cross both north-south and east-west bound roads at the same time. However, ineffective diagonal crosswalk marking, and lack of signs reduces the use of diagonal crosswalks which in turn results in jaywalking, often in unsafe capacities. The objective of this study is to determine the impacts of pedestrian-caused delay and safety impacts due to the misuse of a diagonal crosswalk. To better understand the impacts, a camera-based data collection was conducted during a four-hour period …

Demand Prediction And Inventory Management Of Surgical Supplies, Rajon Paul Pantha

Graduate Theses and Dissertations

Effective supply chain management is critical to operations in various industries, including healthcare. Demand prediction and inventory management are essential parts of healthcare supply chain management for ensuring optimal patient outcomes, controlling costs, and minimizing waste. The advances in data analytics and technology have enabled many sophisticated approaches to demand forecasting and inventory control. This study aims to leverage these advancements to accurately predict demand and manage the inventory of surgical supplies to reduce costs and provide better services to patients. In order to achieve this objective, a Long Short-Term Memory (LSTM) model is developed to predict the demand for …

Modbus Rtu For Embedded Cyber Secure Inverter Controller, Brady Mcbride

Graduate Theses and Dissertations

The Modbus communication protocol is a widely adopted communication standard in industrial control systems. This communication protocol is known for being reliable and straightforward to implement while being versatile in terms of its operating parameters while supporting multiple formats over various hardware infrastructures and architectures. Many intelligent devices such as Programmable Logic Controllers (PLCs), Human-Machine Interfaces (HMIs), Internet-of-Things (IoT), and various Operational Technologies (OT) utilize Modbus for their communication systems. These types of systems must communicate with each other through a standardized and central communication process. To support the integration of these modular systems, a Field-Programmable Gate Array (FPGA) can …

Tangential Flow Treatment Of Poultry Processing Wastewater Using Stainless Steel Ultrafiltration Membrane, Saubana Olorunsola Dada

Graduate Theses and Dissertations

The current treatment of poultry processing wastewater (PPW) requires a large expanse of land, takes time, and requires chemical usage. The wastewater is typically treated prior to discharge. Apart from aiming to reuse the treated water for non-potable activities, this project aimed to reduce the footprint and time required for PPW treatment. To intensify the PPW treatment units, we studied the possibility of replacing dissolved air floatation (DAF) with a stainless steel ultrafiltration membrane (SSUF). Combined PPW from all processing units taken before the first DAF and the second DAF were used for this study with no pretreatment. The SSUF …

Design Approaches To Enhance Power Density In Power Converters For Traction Applications, Shamar Christian

Graduate Theses and Dissertations

This dissertation presents a design strategy to increase the power density for automotive Power Conversion Units (PCUs) consisting of DC-DC and DC-AC stages. The strategy significantly improves the volumetric power density, as evident by a proposed PCU constructed and tested having 55.6 kW/L, representing an 11.2 % improvement on the Department of Energy’s 2025 goal of 50 kW/L for the same power electronics architecture. The dissertation begins with a custom magnetic design procedure, based on optimization of a predetermined C-core geometrical relationship and custom Litz wire. It accounts for electrical and thermal tradeoffs to produce a magnetic structure to best …

Dpd Guided Insight On The Formation Process Of Polyethersulfone Membranes By Nonsolvent Induced Phase Separation And The Effects Of Additives, Eric Ledieu

Graduate Theses and Dissertations

Dissipative particle dynamics (DPD), a coarse grain simulation method, was applied to the membrane formation process of non-solvent induced phase separation (NIPS) to gain further insight on the mechanism of certain variables and how they affect the final morphology. NIPS involves two solutions, an organic polymer dissolved in an organic solvent colloquially called the dope and an aqueous coagulation bath, brought into contact with one another. The solvents then mix, causing the polymer to fall out of solution as an asymmetric membrane with a dense surface layer and a more open subsurface layer in response to the decreasing solubility. Polyethersulfone …

Effect Of Human Decellularized Skeletal Muscle On Recovery From Volumetric Muscle Loss Injury, Jacob Schluns

Graduate Theses and Dissertations

Volumetric muscle loss (VML) overwhelms muscle’s robust capacity for regeneration. A key event in the etiology of VML injury is the bulk loss of structural cues provided by the underlying extracellular matrix (ECM). While muscle is a highly structured tissue, with cell and ECM alignment in the direction of contractile force production, the impact of scaffold alignment on recovery remains unclear. Bulk human decellularized skeletal muscle (DSM) tissues were sectioned into 10 x 1-2 mm fibers. VML defects were repaired using multi-fiber implants consisting of approximately 8 fibers per defect arranged into two layers. Fibers were oriented 1) to the …

Development Of Medical Device For Volume Status Assessment Using Peripheral Venous Pressure, Audra Beneux

Graduate Theses and Dissertations

The severe side effects of acute dehydration and blood loss may be prevented if assessed and treated quickly. As amplifier technology has improved, small peripheral venous pressure (PVP) signals collected using a transducer on an intravenous catheter can be analyzed to monitor patient volume status. This thesis details the development of an embedded system prototype that quickly and accurately assesses volume status using PVP analysis. The volume prediction algorithm classified 10 seconds of PVP data as “dehydrated” or “resuscitated”. The hardware design consisted of four primary areas: analog signal conditioning, processing, user interaction, and power. After data collection, the signal …

Digital Simulations Of Memristors Towards Integration With Reconfigurable Computing, Ivris Raymond

Computer Science and Computer Engineering Undergraduate Honors Theses

The end of Moore’s Law has been predicted for decades. Demand for increased parallel computational performance has been increased by improvements in machine learning. This past decade has demonstrated the ever-increasing creativity and effort necessary to extract scaling improvements in CMOS fabrication processes. However, CMOS scaling is nearing its fundamental physical limits. A viable path for increasing performance is to break the von Neumann bottleneck. In-memory computing using emerging memory technologies (e.g. ReRam, STT, MRAM) offers a potential path beyond the end of Moore’s Law. However, there is currently very little support from industry tools for designers wishing to incorporate …

Polymeric Biomaterials Approaches For Engineering The In Vitro Cellular Microenvironment For Mscs, Mahsa Letter-Mahsa Haseli

Graduate Theses and Dissertations

Cell therapy is a technology that relies on replacing diseased or dysfunctional cells with healthy functioning ones. One of the cells used for such advanced therapies are stem cells, owing to their ability to differentiate into specific cells required for repairing damaged or defective tissues or cells. The majority of cell-based products are intended to transiently persist in the patient, secreting factors which then allow the patient’s body to heal; in these products, the cells are subsequently eliminated from the body. Furthermore, unique manufacturing platforms, in addition to novel commercialization strategies, will be required to create a successful, sustainable cell …

Analysis Of An Isolated Bidirectional Ćuk Converter, Yeny Hau Chen

Graduate Theses and Dissertations

The objective of this thesis is to perform an analysis of the isolated bidirectional Ćuk dc-dc converter topology and demonstrate the advantages and operation of this configuration through simulations using MATLAB/SimulinkTM and measurements collected from a 1.5-kW prototype tested at the Engineering Research Center (ENRC) laboratory of the University of Arkansas. The idea of integrating an active-clamp snubber circuit on each side of the converter, proposed by Dr. Sudip Mazumder from the University of Illinois, Chicago, limits the additional voltage stresses on the components due to the energy from the transformer’s leakage inductance. This is studied in this thesis to …

Preparing Homogenous Composites Of Collagen And Cellulose Nanocrystals For Tissue Engineering Research, Zachary Stanley

Biological and Agricultural Engineering Undergraduate Honors Theses

Advancements in medicine and our understanding of stem cells have led to a greater emphasis on further developing research focused on tissue engineering. This research has led to the rise of both two-dimensional and three-dimensional scaffolds that can be utilized to repair bone, skin, vascular, and potentially even nervous tissue. One of the prominent compounds used in modern scaffolds is collagen-based hydrogels due to their low antigenicity and ability to provide structure to cells. There is potential to further improve upon this three-dimensional scaffold by incorporating cellulose nanocrystals (CNCs) into a composite hydrogel with collagen. The addition would increase the …

Analyzing Energy Use From Arkansas Public School Buildings, Oscar Morton

Biological and Agricultural Engineering Undergraduate Honors Theses

Energy is a key global resource in society and greenhouse gas (GHG) emissions related to the consumption of energy have detrimental effects on the planet. With energy consumption increasing, exponential population growth, and diminishing natural resources necessary for energy production, the relevance of energy efficiency is dramatically increasing. In this project, I analyzed energy usage data from a set of public school buildings from one school district in northwest Arkansas from 2018, before targeted energy efficiency practices were implemented, through 2022 to see if energy usage changed over this short period. The objectives of analyzing energy data were to determine …

Transcriptome Profiling Of A Synergistic Volumetric Muscle Loss Repair Strategy, Kevin Roberts, John Taehwan Kim, Jacob Schluns, Grady Dunlap, Jamie Hestekin, Jeffery Wolchok

Biomedical Engineering Faculty Publications and Presentations

Volumetric muscle loss overwhelms skeletal muscle’s ordinarily capable regenerative machinery, resulting in severe functional deficits that have defied clinical repair strategies. In this manuscript we pair the early in vivo functional response induced by differing volumetric muscle loss tissue engineering repair strategies that are broadly representative of those explored by the field (scaffold alone, cells alone, or scaffold + cells) to the transcriptomic response induced by each intervention. We demonstrate that an implant strategy comprising allogeneic decellularized skeletal muscle scaffolds seeded with autologous minced muscle cellular paste (scaffold + cells) mediates a pattern of increased expression for several genes known …

The Wideband Tunability Of Double Gunn Diodes, Latarence Butts, Samir M. El-Ghazaly

Electrical Engineering Faculty Publications and Presentations

Gunn diodes use the Ridley–Watkins–Hilsum effect to generate low noise millimeter wave signals for communication and sensing applications. However, Monte Carlo calculations indicate that the velocity–field characteristics of compensated GaAs contain a second peak due to phonon scattering. A novel device that leverages this double Ridley–Watkins–Hilsum effect to achieve ultra-wideband tunability of low-noise millimeter waves is proposed in this article. The second region of negative differential mobility is gradually introduced in seven mobility profiles, which are each simulated in eight device lengths. It is found that a 2.5 μm Gunn diode with a compensation ratio of 0.6 operating at …

A Biochemical Necroptosis Model Explains Cell-Type-Specific Responses To Cell Death Cues, Geena V. Ildefonso, Marie Oliver Metzig, Alexander Hoffmann, Leonard A. Harris, Carlos F. Lopez

Biomedical Engineering Faculty Publications and Presentations

Necroptosis is a form of regulated cell death associated with degenerative disorders, autoimmune and inflammatory diseases, and cancer. To better understand the biochemical mechanisms regulating necroptosis, we constructed a detailed computational model of tumor necrosis factor-induced necroptosis based on known molecular interactions from the literature. Intracellular protein levels, used as model inputs, were quantified using label-free mass spectrometry, and the model was calibrated using Bayesian parameter inference to experimental protein time course data from a well-established necroptosis-executing cell line. The calibrated model reproduced the dynamics of phosphorylated mixed lineage kinase domain-like protein, an established necroptosis reporter. A subsequent dynamical systems …

Early Introduction Of 3d Modeling Modules Promotes The Development Of Simulation Skills In Downstream Biomedical Engineering Curricula, Mary S. Jia, Raj R. Rao, Mostafa Elsaadany

Biomedical Engineering Faculty Publications and Presentations

Background

Recent advancements in additive manufacturing have made 3D design a desirable skill in combating the historically slow development of biomedical products. Due to the broad applicability of additive manufacturing to biomedical engineering, 3D design and 3D printing are attractive educational tools for biomedical engineering students. However, due to the multidisciplinary nature of biomedical engineering, finding a suitable spot in the curriculum to teach students basic and application-based skills for 3D manufacturing is difficult. Furthermore, prior training in fundamental 3D design skills may be needed to support the use of application-based supplementary content.

Results

We designed a SolidWorks Simulations toolkit …

Riverine Commons And Institute Framework Plan, Community Design Center

Community Design Center Project Reports

The nonprofit Watershed Conservation Resource Center is restoring a 98-acre riparian wetland landscape near downtown Fayetteville as a River Commons and Institute. The Framework Plan combines watershed restoration with architecture and urban design to house a river education center, a visitor interpretive center, walking trails, passive recreation facilities including bird watching and canoeing, and outdoor heritage exhibitions. The Plan operates at the intersection of anthropology, ecology, and design in developing a lasting and robust riverine knowledge fund across space and time.

Experimental And Computational Analysis Of Broadband Thz Photoconductive Antennas, Zachary Uttley, Jose Santos Batista, Bilal Pirzada, Magda El-Shenawee

Electrical Engineering Faculty Publications and Presentations

The work presents the fabrication and measurements of four LT-GaAs photoconductive terahertz (THz) antennas with different geometries of metallic electrodes. The goal is to analyze the overall bandwidth of the antennas through a comparison between the spectra of the generated photocurrent in the antenna gap, the radiated electric field THz pulse, and the S₁₁ parameter of the metallic electrodes. The photocurrent density and the S₁₁ parameters are computed using COMSOL multiphysics, while the generated THz pulse was experimentally measured using a time-domain spectroscopy system. The polarizations of the photoconductive antennas are experimentally measured, using x-cut quartz crystal halfwave …

Effect Of Stress Interaction On Multi-Stress Accelerated Life Test Plan: Assessment Based On Particle Swarm Optimization, Ekene Gabriel Okafor, David Ryan Huitink

Mechanical Engineering Faculty Publications and Presentations

Sustainability of products that seek to maintain ecosystem balance, such as electric vehicles or solar system inverters, often require extensive testing during their developmental stages in a manner that minimizes wastage and drives creativity. Multi-stress accelerated test planning is often used for these products, their subsystems and components if their in-service failures are driven by multiple stress factors. Multi-stress accelerated life testing (ALT) often expedites time to failure for highly reliable products. Many studies assume model parameters that may not be appropriate for the considered stress factors. Most importantly, the effect stress interaction has on the ALT plan is often …

Local Il-10 Delivery Modulates The Immune Response And Enhances Repair Of Volumetric Muscle Loss Muscle Injury, Tai Huynh, Cassandra Reed, Zain Blackwell, Peyton Phelps, Luis Carlos Pinzon-Herrera, Jorge Almodovar, David A. Zaharoff, Jeffery Wolchok

Biomedical Engineering Faculty Publications and Presentations

This study was designed to test the hypothesis that in addition to repairing the architectural and cellular cues via regenerative medicine, the delivery of immune cues (immunotherapy) may be needed to enhance regeneration following volumetric muscle loss (VML) injury. We identified IL-10 signaling as a promising immunotherapeutic target. To explore the impact of targeting IL-10 signaling, tibialis anterior (TA) VML injuries were created and then treated in rats using autologous minced muscle (MM). Animals received either recombinant rat IL-10 or phosphate buffered saline (PBS) controls injections at the site of VML repair beginning 7 days post injury (DPI) and continuing …

Plural Communities: A Cultural Mapping Project + A Framework Plan For Cherokee Village, Arkansas, Community Design Center

Community Design Center Project Reports

What do urban designers do with culture? How might we redevelop a mid-century modern planned community through the mapping of cultural influences that shaped it? We explored memory and heritage central to cultural mapping and its participatory-based forms of public inquiry. 54 drawings integrate maps, folklore materials, archived media, photographs, and new drawings into five synchronic cultural frameworks that shaped Cherokee Village—Native American heritage, Ozark pioneer and folk heritage, camping and scouting, midcentury planned communities, and regional modernism in design and planning.

Cherokee Village was developed within a mid-twentieth century planning ethos that valued uniformity …

Third Arkansas Record Of Mountain Bluebird (Sialia Currucoides), With Notes On Habitat And Behavior, G. R. Graves

Journal of the Arkansas Academy of Science

Mountain Bluebird (Sialia currucoides) breeds in western North America and winters east to the Great Plains from Nebraska to Texas (Johnson and Dawson 2020). Vagrants are occasionally reported in eastern North America, mostly from November through March, but relatively few wintering records have been documented in the lower Mississippi Valley east of 96° W longitude and south of 37° N latitude.

Academy Presidents And Institutional Members, Academy Editors

Journal of the Arkansas Academy of Science

No abstract provided.

Helminth Parasites Of Northern Cottonmouth, Agkistrodon Piscivorus (Ophidia: Viperidae), From Arkansas, C.T. Mcallister, C.R. Bursey, H.W. Robison

Journal of the Arkansas Academy of Science

The Northern cottonmouth, Agkistrodon piscivorus is a large, semiaquatic viperid snake found statewide in Arkansas. Although a great deal has been published on helminth parasites of A. piscivorus from other parts of its range, little (outside of its cestodes) is known about those other helminths occurring in cottonmouths of the state. In our survey, we examined seven adult A. piscivorus from Polk County and a single specimen from Calhoun County. Several helminth parasites were found, including three trematodes, Styphlodora magna, Renifer ellipticus, and Paralechriorchis syntomentera, two nematodes, an unknown larval ascarid and Physaloptera abjecta, an oligacanthorhynchid acanthocephalan cystacanth, and a …

Investigation Of A Recent Landslide In Fort Smith, Arkansas, D. Mayo, M.J. Thomas, A. Burns, J. Pruitt, P. Karr

Journal of the Arkansas Academy of Science

A morphologically youthful slope failure, herein referred to as the Landfill Landslide, was identified in a remote section of the City of Fort Smith Landfill, and permission was obtained to investigate. The slide on a deforested, NW-facing 27% slope beneath a linear head scarp about 200 meters long. One end of the head scarp curves abruptly downhill and transforms into a distinct lateral scarp greater than 100 meters long. The surface of the slide is about 24,000 m2 (6 acres) in area and is easily distinguished from adjacent intact slopes by its hummocky morphology and transverse ridges and valleys. The …

Determination Of Fatty Acid Concentrations In Various Strains Of Freshwater Green Picoplankton Algae (Class Eustigmatophyceae), P. Ashcraft, R. Jacks, B. Martinez, J. Rodriguez, A.B. Burns, A. Gurnsey, L. Taylor, A. Teague, J. Totty, V.L. Fox, A. Williams

Journal of the Arkansas Academy of Science

Algae are of scientific and commercial interest due to their ease of culture and high fatty acid content. The extracted fatty acids from these phytoplankton may potentially be used as an additional test for phylogenetic classification of new algal strains (Tonon et al. 2002), as well as in a supplement for human consumption and producing next-generation biofuels. Of interest is the fatty acid content contained within various algal isolates within the class Eustigmatophyceae. Algal strains were collected and isolated from locations in Lake Chicot in Arkansas, Tower Pond and Lake Itasca at Itasca State Park in Minnesota, and Thayer Lake …