Digital Commons Network^™

Predicting The Impact Of Resource Delays On A Construction Project’S Critical Path Using Monte Carlo Simulation, Colby Weishaar

Graduate Theses and Dissertations

The construction industry is a complex and evolving industry, making the project manager’s job of planning, organizing, and making decisions a difficult one. One of the most difficult decisions throughout a project is determining what resources are needed to complete a task by the deadline. Uncertainties cause risks within the schedule often creating delays for which the project manager must develop a mitigation plan once risks are identified. After conducting a review of the literature, no research was found examining the use of an analytical model to estimate the delays caused within the resource allocation process. If an analytical model …

The Role Of Co2 Sublimation In Mass Wasting And Landscape Evolution Under Martian Conditions, Matthew Edwin Sylvest

Graduate Theses and Dissertations

Here we present the first set of laboratory experiments under martian atmospheric conditions which demonstrate that the sublimation of CO2 ice from within the sediment body can trigger failure of unconsolidated, regolith slopes, and can measurably alter the landscape. Previous theoretical studies required CO2 slab ice for movements, but we find that only frost is required. Hence, sediment transport by CO2 sublimation could be more widely applicable (in space and time) on Mars than previously thought. This supports recent work suggesting CO2 sublimation could be responsible for recent modification in martian gullies.

A second set of experiments were carried out …

Species And Cultural Management Of Earthworms On Golf Course Turf In Arkansas And Oklahoma, Paige Elizabeth Boyle

Graduate Theses and Dissertations

As earthworms feed, they can egest soil and nutrient-rich aggregates (casts) on the soil surface. In low-cut turfgrass systems, such as golf course greens, tees, and fairways, surface casting can result in a muddy playing surface, ball roll issues, weed and pest invasion, reduced aesthetics, surface softening, and reduced photosynthesis. Because the use of pesticides for earthworm control is illegal in the U.S., earthworm casting must be managed through cultural practices. Sand topdressing is one method of earthworm control studied for use on golf courses, with the supposition being that the abrasive sand particles will deter the soft-bodied earthworms from …

Digital Palace Of Nestor: Assessing Mycenaean Palatial Complex Construction Of Socio-Political Status And Navigation Through Architecture, Caleb Ward

Graduate Theses and Dissertations

Because architecture necessitates the conscious planning of space, its consequences for navigation and socio-political status are equally deliberate and have indirect effects. This research combines experiential and spatial syntax techniques to gain a deeper understanding of how Mycenaeans shaped space to construct status and navigation in the Palace of Nestor at Pylos. Using a digital reconstruction of the palace ensured the most accurate experiential data by utilizing a whole, albeit virtual, version of the site. Without employing a digital reconstruction, the only experiences with the site would occur in the ruinous, actual site preventing complete experiences with how the site’s …

Engineering The Structure Of The Human Acidic Fibroblast Growth Factor To Enhance Its Stability And Cell Proliferation Activity, Julie Davis Eberle

Graduate Theses and Dissertations

Human acidic fibroblast growth factor (hFGF1) is a protein well known for its role in cell growth and differentiation. To elicit these cell-signaling processes, hFGF1 non-selectively binds to any one of the seven cell surface hFGF receptor isoforms. Due to its significant involvement in tissue repair activity, hFGF1 is a prime candidate for novel wound healing therapeutics. However, one drawback toward its use as a novel wound healing therapeutic is the poor inherent thermal stability of hFGF1, as it has been found to unfold near physiological temperature. The cause of this instability is strong electrostatic repulsion created by a dense …

The Perceptions Of Efl Teachers About Their Pre-Service Preparation In Iraqi-Kurdistan, Nawzar Haji

Graduate Theses and Dissertations

The booming economy in Iraqi-Kurdistan during the last decade attracted hundreds of international companies to the region. The young Kurdish workforce seeks secure jobs that are well paid in such companies. Therefore, they need to be proficient in English. Besides, in general the Kurdish young generation has a positive attitude towards English and consider it the language of science, business, economy, tourism and prestige. Hassan (2014) states that Kurdish-speaking people generally have a positive opinion about learning the English language and believe that having a degree in English means better chances to get a job.

Therefore, the Kurdistan Regional Government’s …

Securing Soft Ips Against Hardware Trojan Insertion, Thao Phuong Le

Graduate Theses and Dissertations

Due to the increasing complexity of hardware designs, third-party hardware Intellectual Property (IP) blocks are often incorporated in order to alleviate the burden on hardware designers. However, the prevalence use of third-party IPs has raised security concerns such as Trojans inserted by attackers. Hardware Trojans in these soft IPs are extremely difficult to detect through functional testing and no single detection methodology has been able to completely address this issue. Based on a Register-Transfer Level (RTL) and gate-level soft IP analysis method named Structural Checking, this dissertation presents a hardware Trojan detection methodology and tool by detailing the implementation of …

Demonstrating Set-Based Design Techniques- A Uav Case Study, Colin Small

Graduate Theses and Dissertations

The Department of Defense (DoD) and Engineered Resilient Systems (ERS) community seek to improve decision making in the Analysis of Alternatives (AoA) process by incorporating resilience and leveraging the capabilities of model-based engineering (MBE) early in the design process. Traditional tradespace exploration utilizing Point-Based Design (PBD) often converges quickly on a solution with subsequent engineering changes to modify the design. However, this process can lead to a suboptimal solution if an incorrect initial solution is chosen. Enabled by MBE, Set-Based Design (SBD) considers sets of all possible solutions and enables down-selecting possibilities to converge on a final solution. Using a …

A Multi-Objective Affinity-Based Savings Algorithm For Improving Processes In Centralized Warehousing Operations, Mckenlee M. Coco

Graduate Theses and Dissertations

Traditional approaches to improving material management processes in warehousing operations tend to focus on one of three major areas: facility design, order picking and sorting, and order batching. In an effort to improve total system savings, a new affinity function is developed and applied to batching logic to create a multi-objective problem. The proposed multi-objective function incorporates user input to increase adaptability to changing demand and flexibility to changing requirements. Computational experience shows the new function leads to solutions that deviate no more than 25% from the most efficient distance based picking route by the same batching logic, while creating …

Experimental And Model-Based Terahertz Imaging And Spectroscopy For Mice, Human, And Phantom Breast Cancer Tissues, Tyler Bowman

Graduate Theses and Dissertations

The goal of this work is to investigate terahertz technology for assessing the surgical margins of breast tumors through electromagnetic modeling and terahertz experiments. The measurements were conducted using a pulsed terahertz system that provides time and frequency domain signals. Three types of breast tissues were investigated in this work. The first was formalin-fixed, paraffin-embedded tissues from human infiltrating ductal and lobular carcinomas. The second was human tumors excised within 24-hours of lumpectomy or mastectomy surgeries. The third was xenograft and transgenic mice breast cancer tumors grown in a controlled laboratory environment to achieve more data for statistical analysis.

Experimental …

We're All Girls Here, Suzanne Danielle Monroe

Graduate Theses and Dissertations

This is a collection of short stories.

Developing A Hil-Based Software Platform For Testing Electric And Hybrid Vehicle Powertrains, Daniel Schwartz

Graduate Theses and Dissertations

The objective of this thesis is to present a dynamometer test stand with hardware in the loop (HIL) testing capabilities for the evaluation of electric and hybrid vehicle powertrains under realistic driving conditions. The traction inverter and dc/dc converter are two crucial subsystems of the powertrain and new prototypes require significant validation before implementing into production vehicles. As fundamental technologies such as power modules, thermal management systems, and passive components improve; the performance improvements to the overall system must be demonstrated. The plug and play nature of the testbed makes it ideal for making direct comparisons of design iterations under …

Design, Fabrication, And Characterization Of All-Inorganic Quantum Dot Light Emitting Diodes, Ramesh Vasan

Graduate Theses and Dissertations

Quantum dot light emitting diodes are investigated as a replacement to the existing organic light emitting diodes that are commonly used for thin film lighting and display applications. In this, all-inorganic quantum dot light emitting diodes with inorganic quantum dot emissive layer and inorganic charge transport layers are designed, fabricated, and characterized. Inorganic materials are more environmentally stable and can handle higher current densities than organic materials. The device consists of CdSe/ZnS alloyed core/shell quantum dots as the emissive layer and metal oxide charge transport layer. The charge transport in these devices is found to occur through resonant energy transfer …

Glucose Level Estimation Based On Invasive Electrochemical, And Non-Invasive Optical Sensing Methods, Sanghamitra Mandal

Graduate Theses and Dissertations

The purpose of this research is to design and fabricate sensors for glucose detection using inexpensive approaches. My first research approach is the fabrication of an amperometric electrochemical glucose sensor, by exploiting the optical properties of semiconductors and structural properties of nanostructures, to enhance the sensor sensitivity and response time. Enzymatic electrochemical sensors are fabricated using two different mechanisms: (1) the low-temperature hydrothermal synthesis of zinc oxide nanorods, and (2) the rapid metal-assisted chemical etching of silicon (Si) to synthesize Si nanowires. The concept of gold nano-electrode ensembles is then employed to the sensors in order to boost the current …

Evaluating An Academic Bridge Program Using A Mixed Methods Approach, Leslie May Yingling

Graduate Theses and Dissertations

As the demand for college degrees has increased, college enrollment has grown significantly, and economic forces have applied greater pressure on the higher education environment to produce more degrees and better post-graduation outcomes. Many public colleges and universities have felt these pressures distinctly because of their state funding environments and the specific expectations that exist within them. While college aspirations and attendance have broadly improved, achievement gaps persist along cultural, generational, and socioeconomic lines. In an effort to navigate and negotiate institutional goals, public expectations, economic needs, and educational ideals, institutions engage in diverse approaches to recruitment and retention. Academic …

Convergent Set-Based Design In Integrated Analysis Of Alternatives: Designing Engineered Resilient Systems, Zephan Wright Wade

Graduate Theses and Dissertations

This thesis presents a comprehensive package for understanding and expanding set-based design quantification through the definition and demonstration of Convergent set-based design (SBD). Convergent SBD is a technique developed for the Engineered Resilient Systems program sponsored by the Department of Defense. Convergent SBD contributes a repeatable methodology with the goal of mathematically eliminating inefficient sets. The study of Convergent SBD led to the development of dominance identification criteria equations using comparison of statistical means. The demonstration of Convergent SBD also illustrates the effect of mission resilience in the tradespace and the impact mission resilience has on preference. Finally, Convergent SBD …

Fabrication And Characterization Of Graphene Based 2d Materials For Supercapacitors, Anishkumar Manoharan

Graduate Theses and Dissertations

Supercapacitors have attracted a lot attention due to their efficient energy storage. In comparison to batteries, supercapacitors have high capacitance, energy, and power densities per unit mass than conventional capacitors. Carbon based materials are most promising in supercapacitor application due to their outstanding physical and electrochemical behavior. In this work, a facile method to synthesize a nanocomposite electrode consisting of annealed carbon from carbon ink and MoS2 was demonstrated. Effects of various aqueous and solid electrolytes were studied. It was found that the nanocomposite electrode with 10% MoS2 and 1M Na2SO4 as the aqueous electrolyte tested using the three electrode …

Rapid And Sensitive Detection Of Escherichia Coli O157:H7 Using A Qcm Sensor Based On Aptamers Selected By Whole-Bacterium Selex And A Multivalent Aptamer System, Xiaofan Yu

Graduate Theses and Dissertations

Escherichia coli O157:H7 is one of the top five pathogens contributing to foodborne diseases, causing an estimated 2,138 cases of hospitalization in the US each year. The extremely low infectious dose demands for more rapid and sensitive methods to detect E. coli O157:H7. The objective of this study is to select aptamers specifically binding to E. coli O157:H7 using whole-bacterium SELEX (Systematic Evolution of Ligands by Exponential Enrichment) and to create a multivalent aptamer system by rolling circle amplification (RCA) with the selected aptamer sequence for sensitive detection of E. coli O157:H7 using a quartz crystal microbalance (QCM) sensor. Briefly, …

Evaluation Of Terahertz Imaging For Breast Cancer Detection Using Image Morphing, Tanny Andrea Chavez Esparza

Graduate Theses and Dissertations

This thesis proposes the use of a mesh morphing algorithm for the quantitative evaluation of terahertz (THz) images. This work differs from traditional evaluation methods based on qualitative evaluation because it provides a fair and quantitative measurement of the THz imaging system's performance. The objective of the algorithm is to match the alignment, shape, and resolution of the THz and reference pathology images. Therefore, the proposed morphing method provides a pathology reference for a pixel-by-pixel evaluation of the region classification in the THz image. To achieve this, the morphing algorithm aligns the images using the Pearson's correlation coefficient and reshapes …

Understanding The Evolution Of Surface Texture Under Boundary Lubrication, Salil T. Bapat

Graduate Theses and Dissertations

The objective of this research was to understand the evolution of surface texture under boundary/mixed lubrication (BL). Significant material/energy losses occur during BL because of direct contact between the two surfaces. Traditionally, tribofilms have been studied extensively for BL while textures have been used as a static engineering design parameter to enhance lubricant film properties. However, texture is dynamic at the tribological mating interface, where both physical and chemical interactions are continuously modulated. The evolution and the interplay between the tribofilm and texture is least studied in the literature, which is the focus of this research.

MoS2-based lubricants, known for …

Moulins: Down The Arctic Drain, Jonathon Nugent Carlson

Graduate Theses and Dissertations

This observation-style nonfiction documentary film follows a National Science Foundation expedition to the Greenland ice sheet. The bivouac lasted for 25 continuous days. University of Arkansas Professor of Geosciences Matt Covington, Ph.D. teamed up with University of South Florida Professor Jason Gulley, Ph.D. to plan, propose, and ultimately accomplish the research goals of the expedition with the assistance of Ph.D. student Celia Trunz, M.S., and experienced expeditionary team member Vickie Siegel. As an observational-style documentary film, all scientific background information imparted herein is taken directly from interviews conducted with Professor Covington, to minimize opining.

The film begins in mid-flight, as …

Preservice Agricultural Education Teachers And Secondary Education Teachers’ Self-Efficacy And Professional Identity, Hailey Gates

Graduate Theses and Dissertations

During the nineteenth century, a decision was made to separate the preparation of agricultural education teachers from their elementary and secondary counterparts (Hearings, 1908; Heren & Hillison, 1996; Hillison, 1986). The majority of land-grant universities and colleges have continued to prepare agricultural education preservice teachers within the college of agriculture, separate from other secondary education preservice teachers in the college of education (Myers & Dyer, 2004). Despite the differences among content disciplines, teachers who possess a strong sense of self-efficacy and professional identity have higher success rates in the classroom when it comes to collaboration, involvement, and student achievement (Ashton …

The Sleeping Giant: The Effects Of Housing Titan Ii Missiles In Arkansas And Kansas From 1962 To 1987, Michael Johnson Anthony

Graduate Theses and Dissertations

During the Cold War, thirty-six sites across Kansas and Arkansas were selected to house Titan II intercontinental missiles. These devices could strike enemy targets 8,000 nautical miles away all while hitting inside an area of one square mile. These technological marvels quickly became an indispensable part of President Kennedy and Defense Secretary McNamara’s ‘flexible defense’ strategy. While many authors have studied the ramifications of these devices on American foreign policy, few have researched the domestic implications of the missiles. This work looks to fill this void by investigating the Titan II missile program in Arkansas and Kansas from its construction …

Counselors' Self-Discrepancy And Its Impact On Their Burnout And Wellness, Donghun Lee

Graduate Theses and Dissertations

This study explores the relationships between counselors’ professional, personal, and reflected selves as well as between counselors’ self-discrepancies and their burnout and wellness. Moreover, an investigation on the impacts of counselors’ self-discrepancies on their burnout and wellness as a professional was conducted. The use of self has been emphasized in order for counselors to elicit meaningful outcome with clients. To demonstrate the use of self as an instrument of the counseling process, integrating professional, personal, and reflected selves is necessary for counselors. One hundred ninety five (N = 195) professional counselors in Mid-South States, who currently practice, supervise, educate, or …

Computational Fluid Dynamics Model For Air Velocity Through A Poultry Transport Trailer In A Holding Shed, Christian Heymsfield

Graduate Theses and Dissertations

Broiler production in Arkansas was valued at over $3.6 billion in 2013 (University of Arkansas Division of Agriculture Cooperative Extension Service). Consequently, improvement in any phase of the production process can have significant economic impact and animal welfare implications. One area of concern for the poultry industry is thermal stress experienced by the birds after arrival at the processing plant and before they are taken in to be processed, during which time they are left to wait in holding sheds. Various cooling strategies exist to mitigate heat stress in holding sheds, but in most cases it is unlikely that they …

Development Of A Digital Rain-Sensing Irrigation Pump Controller And An Android Enabled Bluetooth Paddlewheel Flowmeter, Jayendra Mishra

Graduate Theses and Dissertations

For better irrigation efficiency, it is recommended that farmers track their water consumption to avoid over-irrigating. However, it is difficult to implement this as it is labor intensive to supervise pumps manually and available technologies require high investment. Therefore, a rain sensing pump controller for 3-phase electric irrigation pumps and a stand-alone portable Android enabled paddlewheel flowmeter has been developed to test their feasibility.

The pump timer is a retrofit device for irrigation pump panels. The controller allows an irrigator to start and stop the pump with less supervision. An infrared rain sensor is integrated with the controller to measure …

Dicamba Effects On Soybean (Glycine Max) Growth, Yield, And Offspring, Mark Spencer Mccown

Graduate Theses and Dissertations

Introduction of a new dicamba-resistant (Xtend) trait in soybean and cotton will increase dicamba herbicide use. Consequently, concern for injury to sensitive crops from off-target movement and tank contamination will likely increase. For soybean, foliar symptoms associated with dicamba damage do not necessarily reflect yield losses; hence, experiments were conducted to determine the effects of dicamba on soybean growth, yield, and offspring. Low rates of dicamba [1/64X (8.75 g ae ha-1) and 1/256X (2.18 g ae ha-1) of a normal 1X field rate (560 g ae ha-1)] were applied at two vegetative growth stages (V4, V6) and at each reproductive …

Interpretation And Fracture Characterization Of Early-Cretaceous Buda Limestone Formation Using Post-Stack 3d Seismic Data In Zavala County, Texas, Andrey Smirnov

Graduate Theses and Dissertations

The Buda Limestone is a naturally fractured Early Cretaceous carbonate formation in south Texas which unconformably underlies the Eagle Ford Shale. Matrix porosity of the Buda is less than 6%, therefore natural fractures improve the potential for commercial hydrocarbon production from this tight limestone formation. This presents a challenge for producers to identify these zones using well log and post stack 3D seismic data typically available to medium or small exploration companies. This project provides a workflow based on well log analysis tied to seismic acoustic impedance (AI) inversion to locate areas of probable natural fractures. Acoustic impedance inversion was …

A Genome Wide Association Study For Fusarium Head Blight Resistance In Southern Soft Red Winter Wheat, Amanda Holder

Graduate Theses and Dissertations

Fusarium head blight (FHB) is a disease of small grains caused by the fungal pathogen Fusarium graminearum. FHB poses potential economic losses and health risks due to the accumulation of the mycotoxin deoxynivalenol (DON) on infected seed heads. The objectives of this study are: 1) evaluate soft red winter wheat (SRWW) lines for resistance to FHB in terms of resistance to initial inoculum (incidence); resistance to spread within the head (severity); resistance to DON accumulation; and resistance to Fusarium damaged kernels (FDK), 2) determine the frequency and effect of known FHB resistance genes and quantitative trait loci (QTL), and 3) …

Design, Fabrication, And Characterization Of Novel Optoelectronic Devices For Near-Infrared Detection, Ahmad Nusir

Graduate Theses and Dissertations

Investigating semiconductor materials and devices at the nanoscale has become crucial in order to maintain the exponential development in today’s technology. There is a critical need for making devices lower in power consumption and smaller in size. Nanoscale semiconductor materials provide a powerful platform for optoelectronic device engineers. They own interesting properties which include enhanced photoconductivity and size-tunable interband transitions.

In this research, different types of nanostructures were investigated for optoelectronic devices: nanocrystals, nanowires, and thin-films. First, lead selenide nanocrystals with narrow bandgap were synthesized, size-tailored, and functionalized with molecular ligands for the application of uncooled near-infrared photodetectors. The devices …