Engineering Commons^™

Prediction Of Rupture In Abdominal Aortic Aneurysm, Qusay Alfaori

Graduate Theses and Dissertations

Studying the development of abdominal aortic aneurysm (AAA) through quantification of its growth kinetics and rupture criteria is important to decrease the risk of this life-threatening event. Uniaxial and biaxial testing of healthy and time-dependent Type-I collagen degraded aortic specimens from pigs was performed. Stress-strain suitable mathematical models describing the behavior of abdominal aortic tissue were utilized to derive specific tissue properties and parameters. Reduction in Type-I collagen fraction was observed using picrosirius red staining method, bright field microscopy, and MATLAB. Finite Element Modeling (FEM) of healthy and time-dependent Type-I collagen degraded abdominal aortas were performed using ABAQUS finite element …

Field Amplified Sample Stacking On Amyloid Beta (1-42) Oligomers Using Capillary Electrophoresis, Sadia Ali Paracha

Graduate Theses and Dissertations

According to recent literature, it is believed that the oligomeric form of amyloid beta (Aβ) is the leading cause of Alzheimer’s disease (1; 8; 10; 12-18). Additionally, recent studies have eluded to the impact of Alzheimer’s disease (AD) both economically and Socially in today’s society where an increase of about 71% of AD related deaths were recorded between 2000 and 2013 (7). Since the oligomeric forms of Aβ vary in size, shape and some believe conformation, it is vital to utilize a separation technique, such as capilllary electrophoresis (CE) to further understand Aβ aggregation. By understanding Aβ aggregation, treatment of …

8 Bit Split Array Based Charge Scaling Digital To Analog Converter With Rail To Rail Buffered Output, Sai Kiran Akula

Graduate Theses and Dissertations

This thesis presents the design, simulation and layout of a silicon carbide (SiC) 8 bit split array charge scaling digital to analog convertor (DAC). The converter consists of the charge scaling capacitor chain with two operational trans-conductance amplifiers (op amp) in voltage follower configuration. The op amps used in the design have the input common mode ranges of 0 to 11.2 V and 4.7V to 14.5V respectively. Additional logic circuit topologies are designed, which help to switch the op amps when needed to provide a rail to rail unity gain at the output. As the design is based on the …

Effects Of Magnetically Induced Micro-Mixing On Nanofiltration Performance, Guanghui Song

Graduate Theses and Dissertations

Nanofiltration (NF) is a relatively new membrane separation process mainly used for removing low molecular weight species from aqueous and non-aqueous solutions. NF membranes suffer from concentration polarization leading to membrane fouling thus compromised membrane performance. Magnetically responsive nanofiltration (NF) membranes functionalized with superparamagnetic nanoparticles (SPNs) attached to the chain ends of grafted polymer nanolayers have been shown to be effective in breaking concentration polarization at the membrane-liquid interface under an appropriate external oscillating magnetic field. Under an oscillating magnetic field, the movement of the polymer chains acts as micro-mixer leading to the suppression of concentration polarization and improved filtration …

Compounds Released From Biomass Deconstruction: Understanding Their Effect On Cellulose Enzyme Hydrolysis And Their Biological Activity, Angele Djioleu

Graduate Theses and Dissertations

The effect of compounds produced during biomass pretreatment on cellulolytic enzyme was investigated. Liquid prehydrolyzates were prepared by pretreating switchgrass using 24 combinations of temperature, time, and sulfuric acid concentration based on a full factorial design. Temperature was varied from 140°C to 180°C; time ranged from 10 to 40 min; and the sulfuric acid concentrations were 0.5% or 1% (v/v). Identified products in the prehydrolyzates included xylose, glucose, hydroxymethylfurfural (HMF), furfural, acetic acid, formic acid, and phenolic compounds at concentration ranging from 0 to 21.4 g/L. Pretreatment conditions significantly affected the concentrations of compounds detected in prehydrolyzates. When assayed in …

Modified Polysulfone Nanofiltration Membrane Synthesis For Hydraulic Fracturing Water Recycle, Blake Alexander Johnson

Graduate Theses and Dissertations

The use of hydraulic fracturing has resulted in significant increases in the yield of oil and natural gas, as water pumped into wells at high pressure cracks the formations and releases the hydrocarbons that are locked in the rocks. This process has created large volumes of brackish water that is very difficult to process and is often disposed of into injection wells. Suspended solids and some dissolved solids are more readily removed, but the multivalent ions found in certain salts can precipitate in a well and complicate the reuse of flowback in future hydraulic fracturing operations.

Nanofiltration, a membrane separation …

Production Of Ethanol From Cereal Food Fines Using Dilute-Acid Hydrolysis, Andrew Edward Arnett

Graduate Theses and Dissertations

Cereal food fines are a leftover by-product from breakfast cereal processing that is typically sold as animal feed or used as a pet food ingredient; however this product could be of greater value as a feedstock for the production of fuel ethanol via fermentation. In order for this material to be fermented it has to be broken down in to simple sugars using hydrolysis. One method of hydrolysis is called dilute-acid hydrolysis, whereby low concentrations of acid are added to the feedstock to facilitate the breaking of chemical bonds. This study investigates the effect of different concentrations of acid to …

Wireless Monitoring Of Driver's Pulse Rate And Temperature Using Hand Gloves Approach, Rohith Reddy Narala

Graduate Theses and Dissertations

There is growing concern about dangers correlated with driving, for people with known cardiovascular diseases. However, the association between having a chronic cardiovascular disease and being involved in a motor vehicle crash remains controversial. This study aims to monitor people with known medical emergencies or other medical conditions while driving [1]. It also helps the co-passengers to be cautious while the person is driving with an abnormal health condition. Designed it to be convenient and also can be easily adaptable by the end user.

The proposed project focuses on a wearable sensor glove that equipped with a pulse rate sensor, …

High-Frequency Transformer Design For Solid-State Transformers In Electric Power Distribution Systems, Roderick Javier Garcia Montoya

Graduate Theses and Dissertations

The objective of this thesis is to present a high- or medium-frequency transformer design methodology for Solid-State Transformer (SST) applications. SSTs have been proposed as a replacement of the traditional 50/60 Hz transformer in applications demanding high-power density. Moreover, due to the high penetration of distributed generation, DC grids, energy storage systems, and sensitive loads, SSTs have been considered as an enabling technology for envisioned future energy systems. These applications demand additional functionalities that may not be achieved with traditional transformers. For example, active power flow control, harmonic suppression, voltage regulation, voltage sag compensation, and reduced size and volume.

In …

Modeling Information Reliability And Maintenance: A Systematic Literature Review, Daysi A. Guerra Garcia

Industrial Engineering Undergraduate Honors Theses

Operating a business efficiently depends on effective everyday decision-making. In turn, those decisions are influenced by the quality of data used in the decision-making process, and maintaining good data quality becomes more challenging as a business expands. Protecting the quality of the data and the information it generates is a challenge faced by many companies across all industrial sectors. As companies begin to use data from these large data bases they will need to begin to develop strategies for maintaining and assessing the reliability of the information they generate using this data. A considerable amount of literature exists on data …

Spotlight On Graphene Research From The Middle East, Kathleen A. Lehman

University Libraries Faculty Publications and Presentations

In an extension to the 2011 article “Reviews of Science for Science Librarians: Graphene” (Lehman 2011), this paper seeks to continue exploring the trend of graphene research but limits its focus to the research production of countries in the Middle East. In addition to reporting on the research output of this group of countries, this article will also examine the most prolific Middle Eastern graphene authors,their supporting institutions and funding agencies, the most cited publications from this group, the journals most used for publication of their work, and the general trend in graphene research growth in the Middle East. As …

Modeling Radiation Heat Transfer For Building’S Cooling And Heating Loads: Considering The Role Of Clear, Cloudy, And Dusty Conditions In Hot And Dry Climates, Salem Ahmed Algarni

Graduate Theses and Dissertations

The influence of transient factors such as sky long wave radiation exchange and atmospheric aerosols (i.e., smog, and dust – made up of sand, clay, and silt) are not carefully considered in current building design and simulation models. Therefore, the research objective was to better understand and account for such variables, resulting in improved radiative predictive capabilities, especially important for hot and dry climates under different sky conditions including clean, cloudy, and dusty. Overall, results of this dissertation provided a better prediction method for sky long wave radiation exchange with a building’s roof and the impact of dust accumulation on …

Traction-Separation Relationships For Hydrogen-Induced Grain Boundary Embrittlement In Nickel Via Molecular Dynamics Simulations, Wesley Allen Barrows

Graduate Theses and Dissertations

The deleterious effects of atomic and molecular hydrogen on the mechanical properties of metals have long been observed. Although several theories exist describing the mechanisms by which hydrogen negatively influences the failure of materials, a consensus has yet to be reached regarding the exact mechanism or combination of mechanisms. Two mechanisms have gained support in explaining hydrogen’s degradative role in non-hydride forming metals: hydrogen-enhanced localized plasticity and hydrogen-enhanced decohesion. Yet, the interplay between these mechanisms and microstructure in metallic materials has not been explained. Accordingly, for this thesis, the three main objectives are: (i) to develop a numerical methodology to …

Alkali Silica Reaction Mitigation Using High Volume Class C Fly Ash, William Joseph Phillips

Graduate Theses and Dissertations

Alkali-Silica Reaction (ASR) is a neutralization reaction that occurs between an acid (silicic acid) and a basic pH pore solution (Calcium Oxide, Potassium Oxide, and Sodium Oxide). ASR causes deleterious expansion within concrete, which can cause durability issues decreasing the life span of concrete. ASR in concrete has been found in increasing quantities since its discovery in 1940 by Stanton. Several cases of ASR have occurred in Arkansas near Fayetteville, Pine Bluff, and Little Rock. The purpose of this research was to develop preventative measures using Class C fly ash in concrete, which contains the moderately reactive aggregates found in …

Swelling-Etching Characterization Of Copper (I) Oxide - Pdms For The Development Of Micro/Nano - Particles Composite Mems Corrosion Sensor, Abdoul Kader Maiga

Graduate Theses and Dissertations

The primary objective for this thesis is to contribute to the understanding of the oxide removal process for a corrosion sensing device. The goal for designing such a device is for monitoring corrosion on metallic structures. The sensing material (6.35mm x 1mm discs) of the device is composed of copper (I) oxide particles mixed in some polydimethylsiloxane (PDMS). The PDMS, “housing,” is meant for controlling the oxidation rate through the sensing material. A solvent was used to facilitate the etchant diffusion through the PDMS matrix. Toluene and acetic acid were the ideal solvent and etchant, respectively, for carrying out the …

Creating Quality Metrics For The Capital Facilities Delivery Industry, Kelsey D. Lamb

Graduate Theses and Dissertations

A standard for industry-wide quality metrics, similar to safety metrics, for the capital facilities delivery industry is investigated and developed with the goal to motivate industry-wide adoption of this new quality metric program. A survey of the literature found key differences between capital facilities and other industries, mainly that other industries focus on the quality of the product while capital facilities focus on maintaining the cost and schedule of a project. Creating a framework that can be used across the industry can potentially lead to uniform improvement of quality for the entire industry. Quality is defined for the capital facilities …

Preventive Maintenance Decision Modeling In Health And Service Systems, Mahboubeh Madadi

Graduate Theses and Dissertations

This dissertation focuses on the preventive maintenance decision modeling in healthcare and service systems. In the first part of this dissertation, some issues in preventive health decisions for breast cancer are addressed, and in the second part, the required characteristics for preventive maintenance of an unreliable queuing system are derived.

Adherence to cancer screening is the first issue that is addressed in this dissertation. Women’s adherence or compliance with mammography screening remained low in the recent years. In this dissertation, we first develop a design-based logistic regression model to quantify the probability of adherence to screening schedules based on women’s …

A Computational Study Of The Potential For Lng Tanker Polystyrene Foam Insulation Failure Under Fire Exposure, Jeffrey David Martinez

Graduate Theses and Dissertations

Liquefied natural gas is shipped across the oceans in large marine carriers. The carriers house the LNG using several different insulation systems. One of these systems involves large aluminum spheres insulated with polystyrene foam. Polystyrene foam is very susceptible to heat degradation. This raised issues as to the extent of possible insulation failure caused by a large ship fire. Experiments were done investigating the nature of polystyrene’s thermal degradation, notably by Brauman, Chen, and Matzinger and Butler. A large scale investigation was also performed by Sandia National Laboratory. However, computational modeling of the degradation was lacking. This work set out …

Understanding Technology Diffusion And Spatial Accessibility In The Home Healthcare Industry, Mehmet Serdar Kilinç

Graduate Theses and Dissertations

Home healthcare is becoming an important alternative to institutionalized care. It not only reduces costs but also increases health outcomes and patient satisfaction. However, the availability and efficiency of home healthcare services need to be improved as the aging population increases in the US. Hence, understanding home healthcare utilization and access are the essential steps to develop strategies ensuring effective and sustainable services to patients.

This research aims to study two main issues in the US home healthcare system: diffusion and long-term impacts of home telehealth and potential spatial accessibility of home healthcare services. Home telehealth is a promising technology …

An Adaptive Large Neighborhood Search Heuristic For The Inventory Routing Problem With Time Windows, Mina Hadianniasar

Graduate Theses and Dissertations

This research addresses an integrated distribution and inventory control problem which is faced by a large retail chain in the United States. In their current distribution network, a direct shipping policy is used to keep stores stocked with products. The shipping policy specifies that a dedicated trailer should be sent from the warehouse to a store when the trailer is full or after five business days, whichever comes first. Stores can only receive deliveries during a window of time (6 am to 6 pm). The retail chain is seeking more efficient alternatives to this policy, as measured by total transportation, …

Numerical Simulation Of Terahertz Wave Interaction With Breast Cancer Tumor Tissue Sections, Abayomi Omotola Omolewu

Graduate Theses and Dissertations

This thesis presents numerical simulation of terahertz (THz) wave interaction with breast cancer tumor tissue sections. The obtained results are expressed in THz images of heterogeneous material that mimics the excised breast cancer tissue sections. The finite-element software package ANSYS High Frequency Structural Simulator (HFSS) was used in this work. HFSS is a full wave frequency domain three-dimensional (3D) electromagnetic simulation package. In this work, four breast cancer tissue models based on pathology images were simulated and images of the models were obtained at 1 THz. An incident Gaussian beam was raster scanned over tissue model configurations and the reflected …

Characterization Of Human Muscle Extracellular Matrix, Lauren Klaire Wilson

Graduate Theses and Dissertations

The performance of extracellular matrix (ECM) biological scaffolds for the treatment of volumetric muscle loss (VML) has shown promising results with regenerating native muscle in animal models and human patients. However, the limitations of these scaffolds include non-specific characteristics based on the original parameters of the muscle that is lost and this is why our group chose to characterize human skeletal ECM. By understanding the characteristics of the native human skeletal ECM, more desired queues for the biological scaffolds being used to treat VML can be provided. Upper limb and lower limb skeletal muscles were commercially obtained, decellularized using common …

Fabrication Of Sub-10 Nm Metallic Structures Via Nanomasking Technique For Plasmonic Enhancement Applications, Stephen Joseph Bauman

Graduate Theses and Dissertations

One area of nanoscience that has become popular in recent years is the study of optics at the nanoscale. Due to enhanced fabrication techniques, new geometries and improved dimensional resolutions have been allowing the creation of nanostructures for use in this area. Nanoscale geometries cause unique optical effects such as enhancement of the signal’s electric field strength at the surface of a substrate. Specifically, structures separated by nanogaps (10 nm and smaller) have been shown to exhibit strong field enhancement within the gaps. This has opened up the potential for surface enhanced spectroscopies, enhanced absorption for photovoltaics, and improved sensing …

Using Peptoids To Build Robust, Efficient Microarray Systems, Dhaval Sunil Shah

Graduate Theses and Dissertations

Recent studies have shown microarrays to be indispensable for various biological applications, allowing for high-throughput processing and screening of biological samples such as RNA, DNA, proteins and peptides using a small sample volume (< 1 µL). Peptoids (poly-N-substituted glycine oligomers) can be used as a substitute for antibodies as capture molecules, as well as coatings for slides in antibody microarrays. The ease of synthesis of peptoids, high customizability with desired bioactivity, and speed of synthesis allows us to build a diagnostic system with a large dynamic range that can detect biomolecules from a minimal sample size. In this study, peptoid-based antibody mimics are designed to have both structural and functional features similar to those of antibodies, including a stable constant region (scaffolding) and a variable region for protein recognition. Peptoids previously screened via combinatorial library synthesis to be specific to bind Mdm-2 (mouse double minute 2 homolog) and GST (gluthathione S-transferase), have been synthesized. The protein recognition peptoids have been conjugated to PEG (polyethylene glycol) molecules with modified end groups; an amine group on one end that allows for immobilization and orientation on the slide, and an azide group on the other end that will allow for attachment to the peptoid through “click chemistry”. The number of capture molecules printed on the slides can be increased by making the available surface area of the slide larger via coating with microspheres. We have determined that partially water soluble peptoids that are also helical, can self-assemble into microspheres. Sequences have been developed that can consistently produce uniform microsphere coatings on slides that increase the overall surface area. A high surface area corresponds to a higher number of binding sites, and therefore a more sensitive system. The work done has shown that slides may be successfully coated in order to potentially improve the detection system.

Broadband High Efficiency Fractal-Like And Diverse Geometry Silicon Nanowire Arrays For Photovoltaic Applications, Omar Hassan Al-Zoubi

Graduate Theses and Dissertations

Solar energy has many advantages over conventional sources of energy. It is abundant, clean and sustainable. One way to convert solar energy directly into electrical energy is by using the photovoltaic solar cells (PVSC). Despite PVSC are becoming economically competitive, they still have high cost and low light to electricity conversion efficiency. Therefore, increasing the efficiency and reducing the cost are key elements for producing economically more competitive PVSC that would have significant impact on energy market and saving environment. A significant percentage of the PVSC cost is due to the materials cost. For that, thin films PVSC have been …

Automatic User Profile Construction For A Personalized News Recommender System Using Twitter, Shiva Theja Reddy Gopidi

Graduate Theses and Dissertations

Modern society has now grown accustomed to reading online or digital news. However, the huge corpus of information available online poses a challenge to users when trying to find relevant articles. A hybrid system “Personalized News Recommender Using Twitter’ has been developed to recommend articles to a user based on the popularity of the articles and also the profile of the user. The hybrid system is a fusion of a collaborative recommender system developed using tweets from the “Twitter” public timeline and a content recommender system based the user’s past interests summarized in their conceptual user profile. In previous work, …

An Empirical Water Quality And Best Management Practice Prioritization Model For Select Arkansas Watersheds, James Mccarty

Graduate Theses and Dissertations

The purpose of this study was to prioritize subwatersheds using water quality data and watershed characteristics. Water quality data was provided through studies by the Arkansas Natural Resources Commission, Beaver Water District, Arkansas Water Resources Center, and publicly available USGS gage data. A total of 114 sites across five HUC-8 watersheds were analyzed, including 12 USGS gages. Watershed characteristic data was retrieved from USGS and Arkansas GeoStore geodatabase repositories. A significant linear relationship between baseflow and stormflow nutrient concentrations was established allowing for the use of baseflow concentrations in the prioritization methodology. Pearson correlation, linear regression, classification and regression tree, …

The Effects Of Strain And Vacancies On The Electric And Vibrational Properties Of Ferroelectric Batio3 From First-Principles, Aldo Serge Michael Raeliarijaona

Graduate Theses and Dissertations

The studies of ferroelectricity (FE) are of technological significance because of the multitude of applicable properties that ferroelectric materials exhibit. The mastery, and control of these properties necessitate the knowledge of the fundamental physics governing these insulating materials.

In this dissertation I present the results of first-principles investigations of the behavior of the fundamental ferroelectric properties under strain, and in the presence of vacancies. In the first part I introduce the important FE properties, their common behavior, and their numerous valuable applications. Following this background on FEs, a review of theoretical methods is presented with topics such as: Density Functional …

Reducing Multiple Access Interference In Broadband Multi-User Wireless Networks, Ali Nayef Alqatawneh

Graduate Theses and Dissertations

This dissertation is devoted to developing multiple access interference (MAI) reduction techniques for multi-carrier multi-user wireless communication networks.

In multi-carrier code division multiple access (MC-CDMA) systems, a full multipath diversity can be achieved by transmitting one symbol over multiple orthogonal subcarriers by means of spreading codes. However, in frequency selective fading channels, orthogonality among users can be destroyed leading to MAI. MAI represents the main obstacle to support large number of users in multi-user wireless systems. Consequently, MAI reduction becomes a main challenge when designing multi-carrier multi-user wireless networks. In this dissertation, first, we study MC-CDMA systems with different existing …

Adaptive Controller Using Runtime Partial Hardware Reconfiguration For Unmanned Aerial Vehicles (Uavs), Nikhil Thomas

Graduate Theses and Dissertations

The goal of this thesis is to explore the feasibility of a multirotor controller system which can dynamically change the arm configuration of a multirotor. Currently most of the multirotor systems have to be powered down, rewired, and programmed with new firmware, to configure how many arms/motors they use to fly. The focus of our effort is to develop a Field Programmable Gate Array (FPGA) based hardware/software controller which uses dynamic partial hardware reconfiguration to switch the arm/motor configuration of a multirotor during operation. We believe that this will make a multirotor more fault tolerant and adaptive. This thesis explains …