Digital Commons Network^™

A Rotating Aperture Mask For Small Telescopes, Edward L. Foley

Master's Theses

Observing the dynamic interaction between stars and their close stellar neighbors is key to establishing the stars’ orbits, masses, and other properties. Our ability to visually discriminate nearby stars is limited by the power of our telescopes, posing a challenge to astronomers at small observatories that contribute to binary star surveys. Masks placed at the telescope aperture promise to augment the resolving power of telescopes of all sizes, but many of these masks must be manually and repetitively reoriented about the optical axis to achieve their full benefits. This paper introduces a design concept for a mask rotation mechanism that …

Advancements In Novel Material Rfid-Based Crack Sensing And Bridge Weigh In Motion, Benjamin Bruciati

Master's Theses

The current infrastructure in the United States is continually deteriorating. Smart structures in civil engineering are becoming increasingly popular due to the performance enhancing systems they contain. Many of these systems are related to sensing and monitoring the structure. Structural health monitoring (SHM) has state of the art technological advances in both these fields. This thesis contributes to the advancements in the SHM field, particularly crack detection and Bridge Weigh-In-Motion (BWIM). The crack detection research uses existing radio frequency identification (RFID) crack detection technology and applies it to a novel material, Ultra High-Performance Concrete (UHPC). This system uses backscatter power …

Children's Books As Cultural Products: A Qualitative Study Of Cultural Representation In Hmong And Non-Hmong American Books, Malina Her

Master's Theses

This study examined the type of cultural practices and values depicted within Hmong American children’s books in comparison to non-Hmong American children’s books from the United States. The purpose was to explore if prior Hmong traditional practices and values reflective of American individualism would extend to Hmong children’s books. Thirty best-seller children’s books were coded using two checklists, one focused on Hmong traditional practices and the other on American values. Results showed that Hmong traditional practices underscored by Hmong adolescents in prior research somewhat extended to Hmong children’s books. Moreover, in some respects Hmong children’s books displayed similar numbers of …

Effect Of Nicotine Exposure On Fatigue Mechanics Of Murine Arteries, Elizabeth Ho

Master's Theses

Nicotine is an addictive substance found in electronic cigarettes (e-cigarettes) and cigarettes, and the use of such products has growing concern because of the prevalent use by young adults. Nicotine exposure degrades arterial tissue and results in increased arterial stiffness, which is linked to cardiovascular events, such as stroke and myocardial infarction. The hypothesis of this research is that fatigue loading reveals changes to the mechanical behavior of nicotine-treated arteries that is more informatively discriminating than stiffness alone. Ten murine arteries, five untreated and five nicotine-treated, were subjected to cyclic fatigue loading in an open-circumferential configuration by a custom tensometer …

Determination Of Demagnetizing Factors In Nanomagnets By First-Order Reversal Curves And Ferromagnetic Resonance, Karl Scott Muster

Master's Theses

Magnetic reversal in nickel nanowire arrays due to an axial, external magnetic field was studied through first-order reversal curve (FORC) measurement. A general function modeling the observed Preisach distribution was developed using the moving Preisach model. Fitting allowed determination of the sample's demagnetizing field at saturation and modeling magnetic reversal with respect to the internal magnetic field. Magnetization dynamics in the sample were studied through ferromagnetic resonance (FMR) measurement to aid in interpreting FORC fit results. Combining FORC and FMR results yielded the saturation magnetization and effective demagnetizing factors of the sample. Similar analysis was performed for a thin film …

Monotonic Testing Of Steel Anchor Straps For Alternative Installation Methods In Wood Frame Shear Walls, Randall Block

Master's Theses

Metal wood-connection hardware straps are sometimes installed in ways not intended by the manufacturers; in particular, a shear-wall anchor strap which was manufactured to be used in straight alignment to connect a post above a particular floor of a building to a post below that floor may instead be bent and wrapped around a floor beam. Four specimens using steel straps were constructed and tested in order to simulate building situations. The experimental specimens had wooden posts and engineered-wood floor beams, connected by straps, arranged so that the load paths passed through the straps being tested; the control specimens had …

Dynamics And Ecological Implications Of The Ulva-Zostera Ecotone In Elkhorn Slough, California, María Vila Duplá

Master's Theses

Ecotones are transitional areas between adjacent ecological communities that have unique ecological qualities defined by space and time scales, and by the interactions between adjacent systems. Ecotones play an essential role in supporting biologically diverse communities, and are sensitive indicators of global change. An Ulva-Zostera ecotone extends along the northern shore of Seal Bend in Elkhorn Slough, an estuary located in central California. Although previous studies have mentioned the presence of the Ulva-Zostera ecotone, this was the first study to focus on understanding its driving factors, spatiotemporal dynamics, and overall ecological implications. A combination of habitat monitoring, water quality assessments, …

Signal Integrity Optimization Of Rf/Microwave Transmission Lines In Multilayer Pcbs, Justin Thien Le

Master's Theses

While allowing for flexible trace routing and device miniaturization, multilayer printed circuit boards (PCB) suffer from performance issues at high frequency due to the impedance mismatch caused by vertical transitions. In this paper, a process for optimizing the high-speed performance of microstrip to stripline transitions in multilayer PCBs is demonstrated. This includes strategic tuning of via dimensions using time-domain reflectometry and an analysis of the use of shielding vias to prevent parasitic cavity resonance. Simulations of optimized 2-layer, 4-layer, and 6-layer microstrip to stripline transitions show a return loss of 20 dB up to 7 GHz. To demonstrate a useful …

Formation Of Clot Analogs Between Co-Flow Fluid Streams In A Microchannel Device, Sue-Mae Saw

Master's Theses

Hemodynamics plays an important role in the formation of blood clots, for which changes in hydrodynamic stresses and transport phenomena can initiate or inhibit the clotting process. The fibrin network is highly influential in the structural mechanics of a clot. This work demonstrated an ability to produce clot analogs at the boundary between co-flow fluid streams, and investigated the dependence of clot shape and density distribution on flow conditions. The time evolution of fibrin clots formed in microchannel flow was investigated using fluorescence imaging. Clots were formed in a polydimethylsiloxane (PDMS) microfluidic device which consisted of a Y-shaped microchannel with …

Effect Of Neighborhood Approximation On Downstream Analytics, Saranya Soundar Rajan

Master's Theses

Nearest neighbor search algorithms have been successful in finding practically useful solutions to computationally difficult problems. In the nearest neighbor search problem, the brute force approach is often more efficient than other algorithms for high-dimensional spaces. A special case exists for objects represented as sparse vectors, where algorithms take advantage of the fact that an object has a zero value for most features. In general, since exact nearest neighbor search methods suffer from the “curse of dimensionality,” many practitioners use approximate nearest neighbor search algorithms when faced with high dimensionality or large datasets. To a reasonable degree, it is known …

Development Of A Computational Elbow Joint Model To Analyze The Effects Of Synovial Fluid On Articular Cartilage During Joint Motion, Abhishek Yellapragada

Master's Theses

While significant advances have been made in the development of computational elbow joint models, fluid-structure interaction (FSI) in the elbow joint has not yet been explored. The objective of this study is to develop a computational elbow joint model to simulate the effects of synovial fluid on articular cartilage during flexion, extension, pronation, and supination. The model was developed with anatomically accurate 3D bone geometries; articular cartilage geometries that were derived from the 3D bone geometries; ligaments defined as linear springs; muscles embedded as joint non-linear stiffness; and a fluid domain that encompassed the joint articulations with a homogenous, incompressible, …

Time-Invariant Tensile Necking Of Blood On An Electrowetting Digital Microfluidic Platform, Curtis Young

Master's Theses

Recent developments in electrowetting-on-dielectric (EWOD) technology have expanded the possibilities for testing methods and investigation of blood. This work evaluated the development of necking geometry of whole blood and red blood cell (RBC) suspensions on a digital microfluidic (DMF) platform. This was achieved by applying tension to liquid droplet specimens on an EWOD-based device using applied electrowetting forces, thereby inducing necking. The deformation of 5 μL fluid specimens was recorded using neck radius and minimum neck width as two characteristic geometric parameters. Tensile tests were performed on phosphate-buffered saline (PBS), whole blood diluted in PBS, and RBCs suspended in PBS …

Stem Cell Based Delivery System In A Non-Regenerative Nail Injury Model, Aundrya Montgomery

Master's Theses

No abstract provided.

Improving Paper-Based Microfluidic Mixing With The Incorporation Of Flow Disrupting Structures, Hannah C. Green

Master's Theses

Paper-based microfluidic devices provide a light-weight, cost effective platform for diagnostic and analytical testing. The goal of this project is to enhance paper-based microfluidic mixing by incorporating fluid flow disrupting structures (referred to here as rib bones) into the microdevice design to expand the analytical capabilities of paperbased microfluidic devices. The devices are fabricated on Whatman CHR-1 chromatography paper. The devices are designed in SolidWorks and printed using a solid ink printer (ColorQube 8580). The wax is penetrated into the paper to create hydrophobic barrier regions by heating in a convection oven until the wax is fully penetrated. The parameters …

From Experimental Studies To Coarse-Grained Modeling: Characterization Of Surface Area To Volume Ratio Effects On The Swelling Of Poly (Ethylene Glycol) Dimethacrylate Hydrogels, Gabriel Zahm

Master's Theses

Understanding the performance of widely applied nanoscale hydrogel biomaterials is an unmet need within the biomedical field. The objective of this master’s thesis project was to evaluate the effects size and surface area has on the in vivo behavior of nanoscale hydrogels. The hypothesis tested was that at the nanoscale, the increased surface area to volume effects of nanoscale hydrogels play and important role in the overall swelling of hydrogels, such that nanoscale hydrogels swell to a greater degree than their bulk counterparts. To investigate this, the bulk swelling behavior of a series of neutral poly (ethylene glycol) di-methacrylate (PEGDMA) …

A Study On The Simultaneous Nitrification And Denitrification Process Of A Membrane Aerated Bioreactor Augmented By Biowish Aqua, Gavrielle Orman

Master's Theses

Nitrogen pollution is a growing problem that is detrimental to the environment and the economy. Traditional treatment of nitrogen is a multi-stage process, expensive, operationally intensive, and requires large land areas. This research studied the effects of BiOWiSH® Aqua (Aqua), a biological enhancement product, on the simultaneous nitrification and denitrification process in a membrane aerated bioreactor (MABR) to determine if it is a feasible application for wastewater treatment. The MABR used during experimentation was a small-scale batch reactor with a continuous flow of air through a silicone membrane.

The effect of carbon source and concentration on nitrogen removal rates and …

A Novel Fiber Jamming Theory And Experimental Verification, Jared Richard Chafetz

Master's Theses

This thesis developed a novel theory of fiber jamming and experimentally verified it. The theory relates the performance, which is the ratio between the stiff and soft states of a fiber jamming chamber, to three relative design parameters: the ratio of the wall thickness to the membrane inner diameter, the ratio of the fiber diameter to membrane inner diameter, and the number of fibers. These three parameters, when held constant across different chamber sizes, hold the performance constant. To test the theory, three different types of fiber jamming chambers were built in three different sizes. Each chamber was set up …

Optimal Direct Yaw Moment Control Of A 4wd Electric Vehicle, Winston James Wight

Master's Theses

This thesis is concerned with electronic stability of an all-wheel drive electric vehicle with independent motors mounted in each wheel. The additional controllability and speed permitted using independent motors can be exploited to improve the handling and stability of electric vehicles. In this thesis, these improvements arise from employing a direct yaw moment control (DYC) system that seeks to adapt the understeer gradient of the vehicle and achieve neutral steer by employing a supervisory controller and simultaneously tracking an ideal yaw rate and ideal sideslip angle. DYC enhances vehicle stability by generating a corrective yaw moment realized by a torque …

In-Plane Cyclic Shear Performance Of Pipe Stem Reinforced Cob Wall, Dezire Q'Anna Perez-Barbante

Master's Theses

This thesis investigates full-scale pipe stem reinforced cob walls under in-plane cyclic shear loads. Cob is the combination of clay subsoils, sand, straw and water that is built in lifts to produce monolithic walls. There is insufficient amount of information on cob as a building material in today’s age. The prior research that exists has examined varying straw content and type, water content, and mixture ratios to determine their effect on strength. There is currently one report that analyzes full-scale cob walls under in-plane loading. This thesis looks to iterate the full-scale tests and specifically studies the effect of reinforcement …

Modeling And Testing Powerplant Subsystems Of A Solar Uas, Luke J. Bughman

Master's Theses

In order to accurately conduct the preliminary and detailed design of solar powered Unmanned Aerial Systems (UAS), it is necessary to have a thorough understanding of the systems involved. In particular, it is desirable to have mathematical models and analysis tools describing the energy income and expenditure of the vehicle. Solar energy income models may include available solar irradiance, photovoltaic array power output, and maximum power point tracker efficiency. Energy expenditure models include battery charging and discharging characteristics, propulsion system efficiency, and aerodynamic efficiency. In this thesis, a series of mathematical models were developed that characterize the performance of these …

A Feasible And Tailored Nutrition Education Intervention For Middle-Schoolers: Coordination With School Nutrition Program And Preliminary Outcomes., Heidi Karner

Master's Theses

No abstract provided.

Study And Analysis Of A Gearless Mechanical Transmission, Arun Lee Malla

Master's Theses

We used a comprehensive geometric and kinematic analysis of the Gearless Mechanical Transmission (GMT) to produce a rigorous analytical model of the system. Given initial design parameters, this model enables accurate computation of the mating geometries and key system attributes over time. Component position, component velocity, and the contact points between components were the primary attributes computed and analyzed by the developed model. The model can also be used to represent transmissions of desired ratios and sizes by altering the design parameters. Therefore, the model enables the theoretical evaluation of any desired GMT system, providing a strong foundation for further …

The Impact Of Relationships On Youth Developmental Outcomes In A Sport-Based Setting, Khalil Griffith

Master's Theses

No abstract provided.

Development Of A Tailored Flight Test Approach For Small Unmanned Aircraft Systems, Neil A. Wolfe

Master's Theses

This document contains the details of a study conducted to determine an effective performance flight test approach specifically for small Unmanned Aircraft Systems (sUAS). This was done by taking proven procedures and documentation from the FAA and the Air Force for manned aircraft and tailoring them specifically for use with sUAS flight test programs. A ‘sUAS Flight Testing Handbook’ was created from the proceedings to aid commercial organizations and recreational developers conducting sUAS research without access to flight test experience. A performance flight test program was conducted with the AeroVironment RQ-20 Puma sUAS using the developed approach to verify that …

Diet Quality And Micronutrient Intake In Long-Term Weight Loss Maintainers, Rebecca W. Pascual

Master's Theses

Objective: This study’s purpose was to examine dietary quality, macronutrient intake, and micronutrient adequacy among long term weight loss maintainers (WLM) in a commercial weight management program.

Methods: Participants were 1,207 WLM in WW (formerly Weight Watchers) who had maintained a 9.1 kg or greater weight loss (29.7 kg on average) for 3.4 years, and had an average BMI of 28.3 kg/m². A control group of weight stable adults with obesity (Controls; N=102) had a BMI of 41.1 kg/m² and 2.3 kg or less weight change over the previous five years.

Results: WLM vs. …

An Application Of Sliding Mode Control To Model-Based Reinforcement Learning, Aaron Thomas Parisi

Master's Theses

The state-of-art model-free reinforcement learning algorithms can generate admissible controls for complicated systems with no prior knowledge of the system dynamics, so long as sufficient (oftentimes millions) of samples are available from the environ- ment. On the other hand, model-based reinforcement learning approaches seek to leverage known optimal or robust control to reinforcement learning tasks by mod- elling the system dynamics and applying well established control algorithms to the system model. Sliding-mode controllers are robust to system disturbance and modelling errors, and have been widely used for high-order nonlinear system control. This thesis studies the application of sliding mode control …

Cubesat Astronomy Mission Modeling Using The Horizon Simulation Framework, Alexander W. Johnson

Master's Theses

The CubeSat Astronomy Network is a proposed system of multiple CubeSat spacecraft capable of performing follow-up observations of astronomical targets of interest. The system is intended to serve as a space-borne platform that can complement existing systems utilized for astronomical research by undergraduate and high school students. Much research and development work has been performed to develop model-based system engineering methodologies and products for CubeSat missions, including the Horizon Simulation Framework. The Horizon Simulation Framework enables the development of system models using the Extended Markup Language (XML), and its simulation program can generate system simulations over model-specified timespans. System requirements …

Investigation Of The Under-Body Flow Field Of A Prototype Long-Range Electric Vehicle, Matthew P. Nguyen

Master's Theses

This thesis presents changes to the design of the Prototype Vehicles Laboratory (PROVE Lab) Endurance Car, an electric car intended to break the Guinness World Record for the single-charge range of an electric vehicle. The design range is 1609.34 km, however at the design velocity of 104.6 kph, the drag is 196 N; which requires more battery capacity than the 100 kWh maximum of the baseline model. With a fixed frontal area, drag reduction can come from lowered velocity or reduced CD. CD reduction is attempted in four ways: side skirts between the fenders, a raised ride height, an elongated …

Experimental Investigation Into Utilizing Synthetic Jet Actuators To Suppress Bi-Modal Wake Behavior Behind An Ahmed Body, Daniel Jacob Baratta

Master's Theses

Testing done on the flat-back Ahmed Body and other bluff bodies has shown the existence of a bi-stable reflectional symmetry-breaking wake at Reynolds numbers ranging from 340 to 2.41 x 10⁶. Several methods of flow control, both active and passive, have been used to improve the efficiency of the Ahmed body but their effect on the bi-stable nature of the wake has not been investigated. This work details the experimental investigation done to determine if piezoelectrically driven synthetic jet actuators are capable of suppressing the bi-stable wake effects observed behind the Ahmed Body. The synthetic jets were designed …

Utilizing Trajectory Optimization In The Training Of Neural Network Controllers, Nicholas Kimball

Master's Theses

Applying reinforcement learning to control systems enables the use of machine learning to develop elegant and efficient control laws. Coupled with the representational power of neural networks, reinforcement learning algorithms can learn complex policies that can be difficult to emulate using traditional control system design approaches. In this thesis, three different model-free reinforcement learning algorithms, including Monte Carlo Control, REINFORCE with baseline, and Guided Policy Search are compared in simulated, continuous action-space environments. The results show that the Guided Policy Search algorithm is able to learn a desired control policy much faster than the other algorithms. In the inverted pendulum …