Engineering Commons^™

Mechanical Properties Of Kenaf Composites Using Dynamic Mechanical Analysis, Thomas A. Loveless

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Natural fibers show potential to replace glass fibers in thermoset and thermoplastic composites. Kenaf is a bast-type fiber with high specific strength and great potential to compete with glass fibers.

In this research kenaf/epoxy composites were analyzed using Dynamic Mechanical Analysis (DMA). A three-point bend apparatus was used in the DMA testing. The samples were tested at 1 hertz, at a displacement of 10 μm, and at room temperature.

The fiber volume content of the kenaf was varied from 20%-40% in 5% increments. Ten samples of each fiber volume fraction were manufactured and tested. The flexural storage modulus, the flexural …

Redox-Controlled Biogeochemical Processes Affecting Arsenic Solubility In Sediments From A Basin-Fill Aquifer In Northern Utah, Xianyu Meng

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The basin-fill aquifers of the American Southwest host elevated concentrations of arsenic in groundwater due to the local geology. Limited information is available on arsenic dynamics in semi-arid and arid regions of the world. This study describes arsenic biogeochemistry and mechanisms of arsenic solubilization for a soil profile collected from the surface to the depth of groundwater in the Cache Valley Basin, Northern Utah.

The first objective was to delineate mechanisms of arsenic solubilization from sediments collected at the study site. Microcosms containing site groundwater and siteoxidized and site-reduced sediments, were monitored over time to observe changes in the solubilization …

Design Of Reliable And Secure Network-On-Chip Architectures, Dean Michael B Ancajas

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The trend towards massive parallel computing has necessitated the need for an On-Chip communication framework that can scale well with the increasing number of cores. At the same time, technology scaling has made transistors susceptible to a multitude of reliability issues. This dissertation demonstrates design techniques that address both reliability and security issues facing modern NoC architectures. The reliability and security problem is tackled at different abstraction levels using a series of schemes that combine information from the architecture-level as well as hardware-level in order to combat aging effects and meet secure design stipulations while maintaining modest power-performance overheads.

The Effect Of Polydimethylsiloxane Substrate Modification On A549 Human Epithelial Lung Cancer Cell Morphology And Biomechanics, Sherissa A. Ward

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The function of cells is dependent on factors including chemical, physical, and mechanical stimuli. A compilation of these factors make up the cellular niche. Though the impact of chemical stimuli has been a known factor for many years, the impact of mechanical and physical stimuli are areas of recent interest now being studied. Previous studies on mechanical and physical stimuli have shown a large impact on various aspects of cellular function.

The effects of cancer are wide spread throughout the entire population. The majority of cancer research and treatment is regarding intracellular chemical pathways. Yet, many forms of cancer are …

A Neural Network Approach To Fault Detection In Spacecraft Attitude Determination And Control Systems, John N. Schreiner

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

CubeSats are employed in a variety of missions as scientific platforms, low-cost technology demonstrators, and in the future, they will conduct service missions as part of larger satellite constellations. CubeSat ADCS designers today are being tasked with designing to ever increasing accuracy requirements. The ability to hold those requirements rests with the attitude control system being robust enough and able to sufficiently respond to changes in the control environment. The need for greater control autonomy is then evident in the need for these systems to be able to react independently to changes in the system dynamics and to identify and …

Characterization Of Novel Chitosan/Polyelectrolyte Nanoparticles, Michaela Wynne Mertz

Biomedical Engineering Undergraduate Honors Theses

Chitosan-based nanoparticles are under investigation as delivery vehicles for drugs, genes, and proteins. Due to the biocompatibility, mucoadhesive nature, and biodegradable nature of chitosan and binding qualities, anionic nature, and biocompatible qualities of heparin, chitosan/heparin nanoparticles (CHNPs) are a promising platform for the delivery of labile proteins. However, the literature lacks a definitive process to control the size, efficiency, and yield of CHNPs at higher concentrations of reagents. Additionally there is a need to improve loading efficiency of CHNPs. In this study CHNPs have been synthesized and characterized for size, yield, protein loading efficiency, and release. The CHNPs were prepared …

Fractionation Of Chitosan Using A Novel Precipitation Method, Davis J. Ward

Biomedical Engineering Undergraduate Honors Theses

Chitosan is a derivative of chitin, a biopolymer found in the exoskeletons of crustaceans. Chitosan is under heavy investigation in the field of drug delivery due to its wide versatility. One such delivery mechanism is the use of hydrogels in cancer immunotherapy delivery. The viscosity of chitosan in its use as a hydrogel depends on the length of chitosan’s N-acetyl D-glucosamine chains, which in turn determines the molecular weight of chitosan. Because there is such a wide range of viscosity in a typical sample of chitosan, there is a need for a simple technique to fractionate the chitosan based on …

Monitoring The Effects Of Mmp Inhibitors On Extracellular Matrix Degradation For Use In Implant Protection, Jake D. Jones

Biomedical Engineering Undergraduate Honors Theses

In order to lengthen the functional time of implantable ECM, the mechanism of degradation must be inhibited. The matrix metalloproteases are the primary method by which ECM is broken down, and the TIMP family of proteins exists as proof that inhibition of these proteases is possible naturally. In particular, the glycoprotein TIMP-1 plays an inhibitory role with most of the MMPs including the collagenases. Furthermore, there exist synthetic or chemical molecules that likewise inhibit the catalytic actions of MMPs. One such molecule is Batimastat (BB-94) which has been proven to be a dose dependent inhibitor of MMPs during the inflammatory …

Impact Of Collagen-Incorporation Within Electrospun Vascular Conduits On The Inflammatory Response And Conduit Mechanics, Karamveer Birthare

Theses and Dissertations

Current surgical alternatives for treating coronary artery diseases are limited in patients with systemic vascular diseases due to unavailability of suitable autologous vessels. The overall goal of this research project is to develop an appropriate tissue engineered vascular grafts (TEVGs) for small-diameter (<6 mm) arteries. Current grafts fail from intimal hyperplasia, caused by hyperproliferation of the smooth muscle cells (SMCs), and graft thrombosis, caused by lack of functional endothelium. Formation of the endothelium, and production of pro-inflammatory species that limits the long term patency, are partially due to the accumulation of oxidized lipid species. In this study, the scaffold composition was systematically varied to assess the inflammatory response and lipid oxidation levels in a rat peritoneal model. Specifically, we determined the collagen to PCL ratio required to limit the production of pro-inflammatory species, while maintaining the required mechanical strength for vascular grafts. Electrospun conduits were prepared from 0%, 10%, and 25% blends of collagen/ PCL (w/w) and implanted in the rat peritoneal cavity for 4 weeks. The results of the study showed that scaffold composition can be varied while keeping the fiber diameter similar. Results from 10% blend conduits showed significantly higher expression for contractile markers compared to the 25% and 0% blend conditions. In general, adding collagen to the PCL conduits reduced the accumulation of oxidized species within the implanted conduits. All conduits exhibited sufficient tensile strength post- implantation. In conclusion, these results demonstrate that introducing 10% collagen into electrospun scaffolds limits the pro-inflammatory characteristics of the recruited peritoneal cells that can potentially improve patency of the TEVGs.

Modeling Force Main Systems For Surge Analysis And Studying Dynamic Response Due To Water Hammer, Wissam Al-Taliby

Theses and Dissertations

The major impact of water hammer on force mains integrity include excessive pressure oscillation that is usually accompanied by pipe vibrations. Models for simulating force main water hammer response have been developed. All of these models were based on the method of characteristics (MOC) and most of them were not calibrated for the lack of efficient field data. Although predicting maximum pressure during the first wave cycle is sufficient in most applications, some applications require precise prediction of pressure damping. One-dimensional models usually over predict pressure oscillation beyond the first cycle since they are based on steady friction expressions. It …

Engineering Properties Of Pile Rebound Soils Based On Cone Penetration Testing, Hadeel Dekhn

Theses and Dissertations

High pile rebound (HPR) has been identified by Florida Department of Transportation (FDOT) to occur during the installation of square prestressed concrete piles at many sites in Florida. Significant pile rebound values of up to 1.5 inch/blow were measured resulting in increased blow counts. Pile refusal is a common occurrence when blow count exceeds 240 blow/ft; leading to pile redesign and economic consequences. The overall objective of this research is to identify the engineering properties of soil deposits which may cause HPR and develop improved correlations that may be used to predict HPR during the design process. Seven sites were …

Design And Verification Environment For High-Performance Video-Based Embedded Systems, Michael Mefenza Nentedem

Graduate Theses and Dissertations

In this dissertation, a method and a tool to enable design and verification of computation demanding embedded vision-based systems is presented. Starting with an executable specification in OpenCV, we provide subsequent refinements and verification down to a system-on-chip prototype into an FPGA-Based smart camera. At each level of abstraction, properties of image processing applications are used along with structure composition to provide a generic architecture that can be automatically verified and mapped to the lower abstraction level. The result is a framework that encapsulates the computer vision library OpenCV at the highest level, integrates Accelera's System-C/TLM with UVM and QEMU-OS …

Modeling Expected Travel Distances For A Common Warehouse Design With Multiple Docks, Mahmut Tutam

Graduate Theses and Dissertations

This thesis develops expected travel distance expressions for both single- and dual-command operations in a unit-load warehouse design with multiple docks. Storage racks are aligned perpendicular to the wall containing docks. Results are presented for continuous and discrete formulations. Because of the importance of how docks are located on a wall, different dock locations are investigated, including uniformly distributed docks along one wall, specified distances between adjacent docks located symmetrically about the mid-point of a warehouse wall, and any distribution of locations along one wall. Among the results obtained, we find that the width-to-depth ratio of the storage area (commonly …

Novel Separation Methods Using Electrodialysis/Electrodeionization For Product Recovery And Power Generation, Alexander Miguel Lopez-Rosa

Graduate Theses and Dissertations

The use of electrodialytic separations for the purification of products has been a vital technique for the past 50 years in the chemical industry. Originally used for demineralization and desalination, electrodialysis and its counterparts have expanded to assist in product purification, waste and hazard removal, and power generation. This research focused on the development of high purity organic acids purification with low power requirements. Work resulted in the development of a new type of electrodialysis process, specifically the use of ionic liquids as a secondary solvent for the development of dual solvent electrodialysis. Through dual solvent electrodialysis, ions were recovered …

Single-Walled Carbon Nanotube Arrays For High Frequency Applications, Asmaa Elkadi

Graduate Theses and Dissertations

This dissertation presents a thorough analysis of semiconducting Single-Walled Carbon Nanotube-based devices, followed by a test structure fabrication and measurements.

The analysis starts by developing an individual nanotube model, which is then generalized for many nanotubes and adding the parasitic elements. The parasitic elements appear when forming the device electrodes degrade the overall performance.

The continuum model of an individual nanotube is developed. A unique potential function is presented to effectively describe the electron distribution in the carbon nanotube subsequently facilitating solving Schrödinger's equation to obtain the energy levels, and to generalize the model for many nanotubes.

It is shown …

Numerical Modeling Of Fluid Migration In Hydraulically Fractured Formations, Toyin Christie Aseeperi

Graduate Theses and Dissertations

Economic production from low permeability shale gas formations has been made possible by the introduction of horizontal drilling and hydraulic fracturing. To ensure that gas production from these formations is optimized and carried out in an environmentally friendly approach, knowledge about the patterns of gas flow in the shale reservoir formation is required. This work presents the development of a shale gas reservoir model for the characterization of flow behavior in hydraulically fractured shale formations. The study also seeks to develop more computationally efficient approaches towards the modeling of complex fracture geometries. The model evaluates the migration patterns of gas …

Maritime Transportation Research Bank, Valeria A. Remon Perez

Industrial Engineering Undergraduate Honors Theses

The maritime transportation system is an important component of the United States’ (U.S.) economy, from commerce activities to freight movement to disaster’ relief. The annual impact of the maritime transportation system on the U.S. national economy is reported as approximately $649 billion of the total U.S. gross domestic product (U.S. Department of Transportation Maritime Administration, n.d.). This impact is attributed to activities related to the movement of goods and people. Indeed, the maritime transportation system plays an important role in international trade by transporting goods such as coal and farm products, which are common commodities for foreign and domestic commerce …

Prioritizing Interdictions On A Shortest Path Network, Hayden D. Summerhill

Industrial Engineering Undergraduate Honors Theses

We consider a variant to the shortest path network interdiction problem with symmetric information from Israeli and Wood (Networks 40, 97-111,2002) which arises in the context of nuclear smuggling prevention. In the basic shortest path interdiction problem, an interdictor has a limited number of interdictions with which he can lengthen arcs in a network in order to maximize the length of the network’s shortest path. This thesis considers the case in which the interdictor does not make all of the interdictions at once. Rather, the interdictor must make the interdictions over a set number of periods. Each period has a …

Data Integrity Verification In Cloud Computing, Katanosh Morovat

Graduate Theses and Dissertations

Cloud computing is an architecture model which provides computing and storage capacity as a service over the internet. Cloud computing should provide secure services for users and owners of data as well. Cloud computing services are a completely internet-based technology where data are stored and maintained in the data center of a cloud provider. Lack of appropriate control over the data might incur several security issues. As a result, some data stored in the cloud must be protected at all times. These types of data are called sensitive data. Sensitive data is defined as data that must be protected against …

Hand Pattern Recognition Using Smart Band, Theerth Raj Munusamy

Graduate Theses and Dissertations

The Importance of gesture recognition has widely spread around the world. Many research strategies have been proposed to study and recognize gestures, especially facial and hand gestures. Distinguishing and recognizing hand gestures is vital in hotspot fields such as bionic parts, powered exoskeleton, diagnosing muscle disorders, etc. Recognizing such gesture patterns can also create a stress-free and fancy user interface for mobile phones, gaming consoles and other such devices.

The objective is to design a simple yet efficient wearable hand gesture recognizing system. This thesis also shows that by taking both EMG and accelerometer data into account, can improve the …

Epitaxial Growth Of Silicon On Poly-Crystalline Si Seed Layer At Low Temperature By Using Hot Wire Chemical Vapor Deposition, Manal Abdullah Aldawsari

Graduate Theses and Dissertations

There has been a growing interest in using low cost material as a substrate for the large grained polycrystalline silicon photovoltaic devices. The main property of those devices is the potential of obtaining high efficiency similar to crystalline Si devices efficiency yet at much lower cost because of the thin film techniques. Epitaxial growth of Si at low temperatures on low cost large grained seed layers, prepared by aluminum induced crystallization method (AIC), using hot wire chemical vapor deposition (HWCVD) system is investigated in this thesis. In this work, different parameters have been studied in order to optimize the growth …

Characterization Of Silicon Phosphorus Alloy For Device Applications, Larry C. Cousar

Graduate Theses and Dissertations

A new material of highly-phosphorus doped silicon for device applications was characterized and analyzed for new material properties. Devices such as NMOS transistors and other CMOS compatible devices may benefit from new materials that reduce external resistances and increase drive currents.

Material characterization requires numerous techniques and technologies to determine electrical, optical, and physical characteristics. For this work, Hall measurement, X-ray Diffraction, Raman Spectroscopy, Photoluminescence Characterization, and Spectroscopic Ellipsometry were used to better understand this new material. The results may lead to new models for silicon phosphorus alloys.

Large-Scale Graphene Film Deposition For Monolithic Device Fabrication, Khaled Al-Shurman

Graduate Theses and Dissertations

Since 1958, the concept of integrated circuit (IC) has achieved great technological developments and helped in shrinking electronic devices. Nowadays, an IC consists of more than a million of compacted transistors.

The majority of current ICs use silicon as a semiconductor material. According to Moore's law, the number of transistors built-in on a microchip can be double every two years. However, silicon device manufacturing reaches its physical limits. To explain, there is a new trend to shrinking circuitry to seven nanometers where a lot of unknown quantum effects such as tunneling effect can not be controlled. Hence, there is an …

Semi-Automated Switching Regulator Modeling Method And Tool, Michael Heath Leonard

Graduate Theses and Dissertations

This thesis presents the results of research targeted at automating the behavioral modeling process for switching voltage regulators. These regulators are commonly used in many application areas including discrete use in larger systems, integrated in a System on a Chip (SoC), or as the primary use case for a design. When used in an integrated system these regulators can be a significant force in slowing down simulations. A common method for removing this slowdown is to use a behavioral model of the switching regulator.

Creating behavioral models can be very time consuming and requires expertise.

The thesis discussion begins by …

Gui Matlab Code To Display Damped, Undamped, Forced And Unforced Mass Spring Systems, Melanie Garcia

Mechanical Engineering Undergraduate Honors Theses

Machine Dynamics and Control is the course offered at the University of Arkansas that deals with damped, undamped, forced and unforced systems. It’s important for students to understand each of these systems for future implementation in the industry and daily real life situations. The three types of damped systems, underdamped, overdamped and critically damped are analyzed in this thesis. As well as only two of the most common forced functions are analyzed, the cosine and sine functions. The objective of this thesis was to develop a GUI code in Matlab that would help students visualize the differences between undamped, damped, …

Interface Property Of Collagen And Hydroxyapatite In Bone, Clint D. Paul

Mechanical Engineering Undergraduate Honors Theses

When looking at bone at the nanoscale, it consists of a matrix of type I collagen and hydroxyapatite (HAP). Type I collagen is the most abundant protein in the body and together with the mineral HAP [Ca10(PO4)6(OH)2] is responsible for most of the structural integrity of bone. Collagen fibrils in bone contain HAP platelets of varying size dispersed between the collagen. The composition of the type I collagen is predicted to play a role in the mechanical properties of the interface. Our research looks at healthy heterotrimeric collagen and mutated homotrimeric collagen containing three identical chains. Both types of collagen …

Self-Organizing Neural Networks Integrating Domain Knowledge And Reinforcement Learning, Teck-Hou Teng, Ah-Hwee Tan, Jacek M. Zurada

Research Collection School Of Computing and Information Systems

The use of domain knowledge in learning systems is expected to improve learning efficiency and reduce model complexity. However, due to the incompatibility with knowledge structure of the learning systems and real-time exploratory nature of reinforcement learning (RL), domain knowledge cannot be inserted directly. In this paper, we show how self-organizing neural networks designed for online and incremental adaptation can integrate domain knowledge and RL. Specifically, symbol-based domain knowledge is translated into numeric patterns before inserting into the self-organizing neural networks. To ensure effective use of domain knowledge, we present an analysis of how the inserted knowledge is used by …

Inertial Force-Driven Synthesis Of Near-Infrared Plasmonic Nanosphere Composites: Physicochemical Characterizations, Joseph Noel Batta-Mpouma

Graduate Theses and Dissertations

Near-infrared (NIR) responsive nanoparticles (NPs) like gold nanorods (GNRs) are important in biomedical fields because of their transparency for biological tissues. Although GNRs are sought after as contrast agents for theranostics in cancer studies, capping ligands like cetyltrimethylammonium bromide (CTAB) for the GNR synthesis are toxic for biological tissues. The need for an alternative to toxic GNRs is of interest to alleviate the problem.

This work aimed to optimize the synthesis of NIR responsive nanosphere composites (NSCs) by inertial force (g-force) using colloidal gold NPs as model, elucidate the mechanism for the NSC formation, and study their detailed physicochemical characteristics. …

Clinical Correlates Of High Cervical Fractional Anisotropy In Acute Cervical Spinal Cord Injury, Aditya Vedantam, Gerald Eckardt, Marjorie C. Wang, Brian D. Schmit, Shekar N. Kurpad

Biomedical Engineering Faculty Research and Publications

Objective: Fractional anisotropy (FA) of the high cervical cord (C1-C2), rostral to the injury site, correlates with upper limb function in patients with chronic cervical spinal cord injury (SCI). In acute cervical SCI, this relationship has not been investigated. The objective of this study was to identify functional correlates of FA of the high cervical cord in a series of patients with acute cervical SCI.

Methods: Traumatic cervical SCI patients who underwent presurgical cervical spine diffusion tensor imaging at our institution were reviewed for this study. FA of the whole cord as well as the lateralcorticospinal tracts (CSTs) was calculated …

Tactile Proprioceptive Input In Robotic Rehabilitation After Stroke, Emmanouil Tzorakoleftherakis, Maria C. Bengston, Ferdinando A. Mussa-Ivaldi, Robert A. Scheidt, Todd D. Murphey

Biomedical Engineering Faculty Research and Publications

Stroke can lead to loss or impairment of somatosensory sensation (i.e. proprioception), that reduces functional control of limb movements. Here we examine the possibility of providing artificial feedback to make up for lost sensory information following stroke. However, it is not clear whether this kind of sensory substitution is even possible due to stroke-related loss of central processing pathways that subserve somatosensation. In this paper we address this issue in a small cohort of stroke survivors using a tracking task that emulates many activities of daily living. Artificial proprioceptive information was provided to the subjects in the form of vibrotactile …