Engineering Commons^™

Utilizing The Hvsr Second Peak For Surface Wave Inversions In The Mississippi Embayment, Ashraf Kamal Himel

Graduate Theses and Dissertations

Ambient noise data from 24 sites within the Mississippi Embayment were analyzed to estimate the fundamental frequency using the horizontal to vertical spectral ratio (HVSR) method. The fundamental frequency ranged from 0.17 to 3.43 Hz for the tested sites. At seventeen of the sites, a second higher frequency HVSR peak, which ranged from 0.617 Hz to 2.154 Hz, was observed in addition to the fundamental HVSR peak. The second peak frequency in the HVSR curve has been attributed by previous researchers as either an odd harmonic of the fundamental peak or a shallow impedance contrast from the Memphis sand layer …

Early Life Flexural Performance And Behavior Of Reinforced Bcsa Concrete Beams, Gabriel Cook

Graduate Theses and Dissertations

Belitic calcium sulfoaluminate cement (BCSA) is a hydraulic, rapid setting alternative to ordinary portland cement (OPC) with reduced energy demands and CO2 emissions. BCSA cement has numerous current and potential applications including transportation repair and precast manufacturing. Currently, limited research exists regarding the structural performance of CSA cements, restricting its potential implementation. Thus, the purpose of this research is to provide insight into the flexural performance and behavior of reinforced BCSA concrete beams. Overall, BCSA concrete had similar cracking and loading behavior to the OPC beams, with increased moment capacity for compression controlled specimens. Furthermore, BCSA concrete showed increased tensile …

Interfacial Tailoring Of Lithium-Ion Batteries By Atomic/Molecular Layer Deposition, Qian Sun

Graduate Theses and Dissertations

Lithium-ion batteries (LIBs) are promising energy storage devices, which play significant roles in addressing problems related to fossil fuels depletion and environmental pollution. Since the 1990s, LIBs have attracted great attention for many applications. Nowadays, LIBs are dominating portable electronics, having several advantages over their forerunners, such as high voltage (3.3~4.2 V) [1,2], low self-discharge (< 5~10 %/month) [3,4], wide operation temperature (-20~60 °C) [5,6], and fast charge/discharge rate [7,8]. However, LIBs deliver an energy density of 100-220 Wh/kg in practice to date, which is far from their theoretical ones, thus hindering their further applications in electric vehicles. Additionally, LIBs have been plagued by other problems, such as intolerance to overcharge/overdischarge, low heat resistance, lithium dendrites growth, large volume change of the silicon anode, large polarization and even safety problems.

Atomic layer deposition (ALD) and molecular layer deposition (MLD) are two important techniques, both proceeding in self-limiting gas-solid reactions and exhibiting excellent capabilities for ultra-thin films, conformal coatings, and controllable growth. They can be employed to address the problems of LIBs mentioned above by …

Examining The Use Of Idealized Granular Material In Validated Dem Simulations, Anjana Thoroppady Kittu

Graduate Theses and Dissertations

Discrete element method (DEM) modeling, is becoming widely used for understanding the micro-mechanical behavior of granular materials at the particle level. This dissertation presents important considerations regarding the experimental boundary conditions and idealized granular materials used in DEM validations.

A common issue in DEM validation studies for direct shear and direct simple shear is selecting top and bottom cap boundary conditions that allow for shear transmission while also being efficiently modeled in the DEM simulations. While the traditional grid boundary types used in the laboratory can be replicated in the numerical models, researchers have also used fixed-particle boundaries, sawtooth boundaries, …

A Generative Statistical Approach For Data Classification In A Biologically Inspired Design Tool, Marvin Manuel Arroyo Rujano

Graduate Theses and Dissertations

The objective of the research this thesis describes is to find a way to classify text-based descriptions of biological adaption to support Biologically Inspired design. Biologically inspired design is a fairly new field with ongoing research. There are different tools to assist designers and biologists in bio-inspired design. Some of the most common are BioTRIZ and AskNature. In recent years, more tools have been proposed to aid and make research in the field easier, for example, the Biologically Inspired Adaptive System Design (BIASD) tool. This tool was designed with the goal of helping designers in early design stages generate more …

Fatigue Performance And Shear Demand Distributions Of Clustered Shear Connectors In Composite Bridge Girders, Brian David Hillhouse

Graduate Theses and Dissertations

The current American Association of State Highway and Transportation Officials (AASHTO) Bridge Specifications assumes uniform shear flow demands at the steel-concrete interface of composite bridge girders. As stud pitch increases to beyond 24 in or as studs become clustered to account for pre-cast concrete decks, this assumed shear demand distribution may be unrepresentative. Understanding shear transfer and resulting demands on headed studs in composite beams are important for ensuring adequate composite design. This study investigates stud demands in composite bridge girders using large-scale fatigue testing and direct pressure measurements for stud force calculations. In this study, two large-scale composite beam …

Accumulation Of Lead By Biofilms In Drinking Water Distribution Systems, Kaleb Oren Belcher

Graduate Theses and Dissertations

Recent crises, such as the one in Flint, MI, indicate that lead exposure from drinking water is a major health concern in the United States. Over six million lead service lines are still in use in the United States, and a universal protocol to safely remove these lead service lines from drinking water distribution systems has not yet been established. This paper calls to attention the potential hazard that biofilms pose as a source of lead in distribution systems, even after the removal of lead pipes. This study used a simulated water distribution system containing a lead source pipe and …

The Effect Of Incorporating End-User Customization Into Additive Manufacturing Designs, Jonathan D. Ashley

Graduate Theses and Dissertations

In the realm of additive manufacturing there is an increasing trend among makers to create designs that allow for end-users to alter them prior to printing an artifact. Online design repositories have tools that facilitate the creation of such artifacts. There are currently no rules for how to create a good customizable design or a way to measure the degree of customization within a design. This work defines three types of customizations found in additive manufacturing and presents three metrics to measure the degree of customization within designs based on the three types of customization. The goal of this work …

Developing Computer Codes For Analyzing Bridge Response Due To Wim Data Truck Loading, Kenneth Patrick Pasley

Graduate Theses and Dissertations

Despite actual truck demographics evolving over the past 30 years, the Arkansas legal loads for bridge posting have not been updated. Custom computer codes were developed.to facilitate comparison between the current Arkansas legal loads for bridge posting and the actual Arkansas truck traffic to ensure that actual reactions are enveloped by the state'. The program, WIMFluence, calculates shear and moment influence lines for a bridge and the resulting shear and moment reactions based on weigh-in-motion data. With supporting scripts, the reactions due to actual Arkansas truck traffic were compared to those due to the current Arkansas legal loads for bridge …

Development Of A Rapid Fatigue Life Testing Method For Reliability Assessment Of Flip-Chip Solder Interconnects, Cody Jackson Marbut

Graduate Theses and Dissertations

The underlying physics of failure are critical in assessing the long term reliability of power packages in their intended field applications, yet traditional reliability determination methods are largely inadequate when considering thermomechanical failures. With current reliability determination methods, long test durations, high costs, and a conglomerate of concurrent reliability degrading threat factors make effective understanding of device reliability difficult and expensive. In this work, an alternative reliability testing apparatus and associated protocol was developed to address these concerns; targeting rapid testing times with minimal cost while preserving fatigue life prediction accuracy. Two test stands were fabricated to evaluate device reliability …

On The Development Of 8,000 Psi Geopolymer Mortar For Practical Use In Field Applications, Remington Gabriel Reed

Graduate Theses and Dissertations

Although there are several perceived benefits from the use of geopolymer binder as an alternative to ordinary portland cement in concrete materials, it is not widely used in field applications. Geopolymer materials have no set guidelines for mixture design and often require heat curing to facilitate strength gain. Additionally, many geopolymers are created using carefully controlled and high quality materials and activator chemicals. These factors greatly affect the practicality of the material. The goal of this research was to create a geopolymer material capable of achieving high compressive strengths at 28 days without heat curing, and using only readily available …

Developing Ultra-High Performance Concrete (Uhpc) With Locally Available Materials, Ali Alsalman

Graduate Theses and Dissertations

Ultra-High Performance Concrete (UHPC) can enhance the durability and resilience of concrete structures. The use of local materials is a fundamental step to save energy and reduce the cost of concrete. The main focus of this research was to develop a UHPC with compressive strength of 150 MPa using locally sources materials. In this study, the effect of fine materials, binder type and content, type of mixer, steel fibers and curing regimes on concrete’s compressive strength were investigated. The relationship between compressive strength and elastic modulus was also studied. This study synthesizes all relevant experimental data in the literature to …

Towards Environmentally Sustainable And Cost-Effective Food Distribution In The U.S., Jasmina Burek

Graduate Theses and Dissertations

Distribution centers (DCs) and supermarkets have an important role in food sustainability, but no previous research has accounted for their environmental impact. The purpose of this research was to assess environmental sustainability of grocery, perishables, and general merchandise DCs; to estimate food storing and retailing impact; and to provide cost-effective strategies to reduce DCs’ environmental impacts. The importance and relevance of the research is threefold: improving sustainability of DCs, food storing, and food retailing. The main method used in this research was the life cycle assessment (LCA) method. An initial study calculated environmental impacts of the Wal-Mart Stores, Inc. DCs, …

Effect Of Continuity Plate Eccentricity On The Performance Of Welded Beam-To-Column Connections, Jason Thomas Norwood

Graduate Theses and Dissertations

Beam-to-column connections in structural steel buildings may have varying degrees of rotational restraint and varying degrees of moment transfer. In fully restrained moment connections, shear is typically transferred through the beam web, while the moment is mostly transferred through the beam flanges which create tension/compression force couples. Column sections that are incapable of resisting these flange forces are often retrofitted with continuity plates within the connection region to improve capacity. In cases of unequal beam depths on either side of the column, an eccentricity between the framed-in beam flange and continuity plate may be required; however, limited research exists to …

Effect Of Cement Content On Concrete Performance, Caleb Joshua Lebow

Graduate Theses and Dissertations

Of all the traditional concrete materials, portland cement has the greatest impact on mixture cost and the environment. Cement is in many ways the glue holding concrete together (Weiss, 1999), and as such, it plays a major role in fresh and hardened concrete properties. Without the proper range of cement in the mixture, low strength development or excessive shrinkage may occur leading to premature deterioration. The Arkansas Department of Transportation (ARDOT) recognizes two types of concrete for use in bridge construction, Class S and Class S(AE). This paper focuses on the findings from testing of Class S(AE) concrete, short for …

Utilizing 3d Printed Analogue Soils To Investigate Specimen Size Effects In Triaxial Testing, Claire Louise Stewart

Graduate Theses and Dissertations

Triaxial testing is one of the fundamental laboratory tests used in geotechnical engineering to determine strength parameters, such as shear strength and friction angle. Investigating the minimum representative elementary volume (REV) can verify the independence of size effects on strength parameters and ensure that the scaled laboratory tests results are consistent, repeatable, and representative of field conditions. Although, REV has been studied for many applications, there is disagreement within geotechnical engineering of a minimum particle diameter to specimen diameter to minimize the size effects related to the REV in consolidated drained (CD) triaxial tests. This research study compared the strength …

Assessing Biofiltration Without Ozonation For Removal Of Trihalomethane Precursors In Drinking Water At The Beaver Water District Drinking Water Treatment Plant, Sana Ajaz

Graduate Theses and Dissertations

Biofiltration without pre-ozonation has the capability to remove natural organic matter (NOM) fractions that serve as precursors of disinfection byproducts (DBPs), which include the four regulated trihalomethanes (THMs) and dichloroacetonitrile (DCAN). Rapid small-scale column tests (RSSCTs) and Pilot Plant filters operated at empty-bed contact times (EBCTs) of 4, 8, and 16 minutes were used to evaluate the performance of nutrient-amended (free ammonia and phosphorus) biofiltration for THM and DCAN precursor removal, as measured using formation potential (FP) tests. NOM surrogates – which include dissolved organic carbon (DOC), specific ultraviolet absorbance (SUVA254) and fluorescence-PARAFAC components – were measured weekly throughout the …

Audio To Architecture: House Music As A Form Generator, Polina Timchenko

Architecture Undergraduate Honors Theses

Contemporary music undergoes similar process of creation to that of the design process through computation and variation. House music as a representation of contemporary culture has a layered structure that allows specific characteristics to identify it as house music. Song components can vary and mix in different orders that form new dynamic compositions. I am going to explore the idea that every house music component can be translated into geometry with the use of parametric design techniques.

Removal Of Carbamazepine From Drinking Water, Adam Johnson, Thomas Krumpolc, Jordan Gadberry, Juan Rodriguez, Paolo Marrero-Rivera, Zachary Wiese

Chemical Engineering Undergraduate Honors Theses

Due to the increasing prevalence of prescription medication over the past few

decades, pharmaceuticals have accumulated in various water sources. This has become a

public health concern because many pharmaceuticals have limited research on the effects

of chronic low-level exposure. According to the World’s Health Organization (WHO),

traces of pharmaceuticals products have been reported in different water sources such as

surface waters, wastewater, groundwater, and drinking water.[1] One pharmaceutical of

interest that has been detected in water sources is carbamazepine. Carbamazepine is a

common pharmaceutical prescribed for the treatment of seizure disorders, neuropathic

pain, and various psychological disorders. It’s mechanism …

Removal Of Carbamazepine From Drinking Water, Juan Rodriguez, Tom Krumpolc, Adam Johnson, Paola Marrero-Rivera, Alex Gadberry, Zach Wiese

Chemical Engineering Undergraduate Honors Theses

Due to the increasing prevalence of prescription medication over the past few decades, pharmaceuticals have accumulated in various water sources. This has become a public health concern because many pharmaceuticals have limited research on the effects of chronic low-levelexposure. According to the World’s Health Organization (WHO), traces of pharmaceuticalsproducts have been reported in different water sources such as surface waters, wastewater, groundwater, and drinking water.[1] One pharmaceutical of interest that has been detected in water sources is carbamazepine. Carbamazepine (CBZ) is a common pharmaceutical prescribedfor the treatment of seizure disorders, neuropathic pain, and various psychological disorders. It’s mechanism of action …

Morphological Features Of Dysplastic Progression In Epithelium: Quantification Of Cytological, Microendoscopic, And Second Harmonic Generation Images, Sandra Patricia Gordon

Graduate Theses and Dissertations

Advances in imaging technology have led to a variety of available clinical and investigational systems. In this collection of studies, we tested the relevance of morphological image feature quantification on several imaging systems and epithelial tissues. Quantification carries the benefit of creating numerical baselines and thresholds of healthy and abnormal tissues, to potentially aid clinicians in determining a diagnosis, as well as providing researchers with standardized, unbiased results for future dissemination and comparison.

Morphological image features in proflavine stained oral cells were compared qualitatively to traditional Giemsa stained cells, and then we quantified the nuclear to cytoplasm ratio. We determined …

Automatic Performance Optimization On Heterogeneous Computer Systems Using Manycore Coprocessors, Chenggang Lai

Graduate Theses and Dissertations

Emerging computer architectures and advanced computing technologies, such as Intel’s Many Integrated Core (MIC) Architecture and graphics processing units (GPU), provide a promising solution to employ parallelism for achieving high performance, scalability and low power consumption. As a result, accelerators have become a crucial part in developing supercomputers. Accelerators usually equip with different types of cores and memory. It will compel application developers to reach challenging performance goals. The added complexity has led to the development of task-based runtime systems, which allow complex computations to be expressed as task graphs, and rely on scheduling algorithms to perform load balancing between …

An Rs-485 Transceiver In A Silicon Carbide Cmos Process, Maria Raquel Benavides Herrera

Graduate Theses and Dissertations

This thesis presents the design, simulation and test results of a silicon carbide (SiC) RS-485 transceiver for high temperature applications. This circuit is a building block in the design and fabrication of a digital data processing and control system. Automation processes for extreme environments, remote connection to high temperature locations, deep earth drilling, and high temperature data acquisition are some of the potential applications for such a system. The transceiver was designed and developed in a 1.2 µm SiC-CMOS process by Raytheon Systems, Ltd. (UK). It has been tested with a supply voltage of 12 V and 15 V, temperatures …

Service Learning Through Extracurricular Activities: Development And Implementation Of A Transportation Engineering Learning Module, Karla Diaz Corro

Civil Engineering Undergraduate Honors Theses

This project developed an easy to implement, low-cost learning module. The module has students compare and contrast the challenges of gathering comprehensive and quality transportation data through advanced technologies and traditional approaches while introducing traffic engineering topics like traffic signal timing. The modules target middle through high school students and first and second year undergraduate engineering students. The learning modules introduce transportation engineering using an engaging open-source computer simulation game adapted by students at the University of Arkansas, as part of a capstone project. The activities in the learning modules require off-the shelf, low-cost computer hardware, making it easy for …

Sulfate Removal From Mine Impacted Waters, Benjamin Drewry, Jean Morales, Tyler Shock, Derek Richard, Luis Sagarnaga, Benjamin Yeldell

Chemical Engineering Undergraduate Honors Theses

Woo Pig Sulfate (WPS) has developed two methods for reducing levels of calcium sulfate in mine impacted waters, a “hot process” and a two-stage nanofiltration process. Both processes were designed to treat gypsum saturated water that is currently being pumped via interceptor wells to prevent the spread of a sulfate plume into a nearby community. Each solution was designed for Freeport McMoran’s Sierrita mine in Green Valley, Arizona, which was visited in order to gain insight about the problem. Below 250 ppm on the treated stream, nanofiltration and the hot process achieve overall recoveries of 84 and 99%, respectively. The …

Removal Of Carbamazepine From Drinking Water, Thomas Krumpolc, Juan Rodriguez, Jordan Alex Gadberry, Zach Wiese, Paola Marrero-Rivera, Adam Johnson

Chemical Engineering Undergraduate Honors Theses

Due to the increasing prevalence of prescription medication over the past few decades, pharmaceuticals have accumulated in various water sources. This has become a public health concern because many pharmaceuticals have limited research on the effects of chronic low-level exposure. According to the World’s Health Organization (WHO), traces of pharmaceuticals products have been reported in different water sources such as surface waters, wastewater, groundwater, and drinking water.^[1] One pharmaceutical of interest that has been detected in water sources is carbamazepine. Carbamazepine (CBZ) is a common pharmaceutical prescribed for the treatment of seizure disorders, neuropathic pain, and various psychological disorders. …

Optimization Of The Practice Of Slow Cooling Steel Bars: A Redesign And Modernization Of Materials, Eryn Johnston

Mechanical Engineering Undergraduate Honors Theses

Throughout the process of steel making, certain grades of steel are a higher risk for defects caused by the inability to quickly diffuse hydrogen through the steel when cooled to room temperature at a normal rate based on the ambient air temperature. To reduce the hydrogen flaking defects that are caused due to hydrogen entrapment in the steel, the process of slow cooling is utilized. This process reduces the cooling rate of steel bars by keeping them at a higher temperature for extended periods and in turn gives the hydrogen a chance to fully dissipate from the steel. In many …

Quasi-Particle Band Structure And Excitonic Effects In One-Dimensional Atomic Chains, Eesha Sanjay Andharia

Graduate Theses and Dissertations

The high exciton binding energy in one dimensional (1D) nano-structures makes them prominent for optoelectronic device applications, making it relevant to theoretically investigate their electronic and optical properties. Many-body effects that are not captured by the conventional density functional theory (DFT) have a huge impact in such selenium and tellurium single helical atomic chains. This work goes one step beyond DFT to include the electron self-energy effects within the GW approximation to obtain a corrected quasi-particle electronic structure. Further, the Bethe-Salpeter equation was solved to obtain the absorption spectrum and to capture excitonic effects. Results were obtained using the Hyberstein-Louie …

Exfoliation, Synthesis, And Characterization Of Nanoscale Te, Takayuki Hironaka

Graduate Theses and Dissertations

Since the experimental discovery of graphene, two dimensional materials have enjoyed more attention and emphasis in academic research than nanowires, but the latter are an important area of study for creating 1D materials, or single atom chains, the next generation materials for advancing electronic devices. Atomically thin layers can be generated from 2D materials with weak bonds in one direction, and by applying this concept to one dimensional weakly bonded materials, we hypothesize that single atom chains with atomic-scale diameters may be produced. Tellurium (Te) and selenium (Se) have lattices consisting of spiral chains oriented along the c-axis, and each …

Gesn Thin Film Epitaxy And Quantum Wells For Optoelectronic Devices, Perry Christian Grant

Graduate Theses and Dissertations

Group IV photonics is an effort to generate viable infrared optoelectronic devices using group IV materials. Si-based optoelectronics have received monumental research since Si is the heart of the electronics industry propelling our data driven world. Silicon however, is an indirect material whose optical characteristics are poor compared to other III-IV semiconductors that make up the optoelectronics industry. There have been major efforts to integrate III-V materials onto Si substrates. Great progress on the integration of these III-V materials has occurred but incompatibility with CMOS processing has presented great difficulty in this process becoming a viable and cost-effective solution. Germanium …