Digital Commons Network^™

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 …

The Effects Of Gender And Communication Style On The Perceptions Of Leaders Within Computer-Mediated Communication, Azra Zukanovic

Master's Theses

The purpose of this study was to examine how perceptions of a leader using computer-mediated communication (CMC) change based on leader gender, communication style, and gender of the recipient. This study had two research questions: whether perceptions of a leader change as a result of congruity or incongruity between the leader’s gender and the leader’s communication style, and whether perceptions of a leader using congruent or incongruent communication styles vary based on the gender of the recipient. This study utilized a 2 (gender of leader: male vs. female) x 2 (communication style: masculine vs. feminine) x 2 (gender of recipient: …

The Role Of Metacognition In Visual Art Education, Renae P. Mccollum

Master's Theses

Metacognition is a conscious activity that occurs in the brain when an individual monitors or controls his or her thinking. Research in multiple fields has found that metacognition plays a significant role in a person’s learning. It is currently a popular trend in general education to teach students metacognitive strategies, and research has shown that it is a practical tool to boost student success. Moreover, metacognition is most effective when it is taught explicitly and regularly practiced by the students. There is a need for more research into the effectiveness of explicitly teaching metacognition in middle and high school visual …

Mindfulness And Resilience As Predictors Of Burnout, Julie Tu

Master's Theses

The faster pace of work due to technological advances and globalization as well as global competition in the workforce may lead to increased chances of stress and burnout among employees. Understanding more predictors of burnout may help companies create better work environments to increase productivity and minimize consequences of burnout (e.g., higher absenteeism, turnover, substance abuse, anxiety, depression). However, not enough research has been done to study the degree to which personality traits predict burnout. Therefore, the purpose of the present study was to examine the degree to which trait mindfulness and trait resilience predict burnout. The study was a …

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 …

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, …

A Phonetic Distance Approach To Intelligibility Between Mam Regional Dialects, Megan Simon

Master's Theses

Mam, an indigenous Mayan language spoken primarily in Guatemala, has considerable internal diversity among its regional dialects. The purpose of this thesis is to estimate their varying degrees of intelligibility and to present groups of dialects whose speakers can be reasonably expected to understand one another. The analysis consists of two parts, the computation of a phonetic distance network and a series of sociocultural interviews. Phonetic distance was measured by Levenshtein distance between cognates in word lists and analyzed with a Neighbor-Net network. Interviews with Mam speakers focused on subjective judgments of intelligibility, contact, and social attitudes. Four main dialect …

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 …

Numerical Simulations Of Atmospheric Rivers And The Rain Shadow Over The Santa Clara Valley, Jesse Dalton Behringer

Master's Theses

This study investigated precipitation distribution patterns in association with atmospheric rivers (ARs). The Weather Research and Forecasting (WRF) model was employed to simulate two strong atmospheric river events. The precipitation forecasts were highly sensitive to cloud microphysics parameterization schemes. Thus, radar observed and simulated Z_H and Z_DR were evaluated to provide information about the drop-size distribution (DSD). Four microphysics schemes (WSM-5, WSM-6, Thompson, and WDM-6) with nested simulations (3 km, 1 km, and 1/3 km) were conducted. One of the events mostly contained bright-band (BB) rainfall and lasted less than 24 h, while the other contained both BB and non-bright-band …

Bilingual Development: Language Input At Home In Sequential Spanish-English Children, Vanessa Noemy Bermudez

Master's Theses

The literature on language input provided to sequential Spanish-English bilingual children has largely been focused on children attending Head Start. The role of siblings in children’s language outcomes has only been investigated in simultaneous bilinguals. The current longitudinal study extended research on language input by investigating early developmental changes in language input and the role of siblings in the language outcomes of 112 sequential Spanish-English bilingual children. Relative exposure was assessed via a parent interview when children were 18 and 56 months of age. Standardized measures of receptive vocabulary and expressive language in Spanish and English were administered at 56 …

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 …

The Toddler Autism Symptom Inventory (Tasi): Use In Diagnostic Evaluations Of Toddlers, Kirsty Coulter

Master's Theses

Although symptoms of autism are present early in life and early diagnosis can lead to better outcomes, there is a lack of validated parent interviews for children under the age of three. We developed the Toddler Autism Symptom Inventory (TASI), an interview form designed to assess the presence and absence of skills and symptoms in children aged 12-36 months. Reliability of symptoms and diagnosis, and validity of algorithms designed in accordance with Diagnostic and Statistical Manual of Mental Disorders, 5^th Edition (DSM-5) and International Classification of Diseases, Tenth Revision (ICD-10) diagnostic criteria were established. Reliability and validity of four …

Does Place Matter? Food Insecurity, Perceptions Of Neighborhood Walkability, And Acculturation As Predictors Of Treatment Outcome In An Early Childhood Obesity Prevention Study, Nana Yaa Marfo

Master's Theses

BACKGROUND: Though cross-sectional studies have established a relationship between environmental factors and weight status, few have looked at how these environmental factors influence response to obesity intervention in adults or children. This study explored the impact food insecurity, neighborhood walkability, and acculturation may have had on the outcomes of an obesity prevention study for low-income, Black and Latinx preschool-aged children.

METHODS: Prior to the start of the primary care-based intervention program (Cloutier et al., 2015), caregivers (n=203) completed measures assessing their household’s food insecurity, their perceptions of their neighborhoods’ walkability, and for Latinx participants, levels of acculturation. Baseline responses were …

First-Time Juvenile Arrestees' Odd Symptoms: The Role Of Parent-School Interaction And Race, Ari Romano-Verthelyi

Master's Theses

Objective.Disruptive behaviors are bidirectionally associated with low-quality parent-school interactions (Hoover-Dempsey & Sandler, 1995). However, Non-White children are more likely to be identified by teachers as behaviorally disruptive (Epstein et al., 2005), more likely to have low-quality parent-school interactions (Serpell & Mashburn, 2012), and more likely to be engaged in the justice system (Hockenberry & Puzzanchera, 2013).Considering that non-White parents may interact with schools and teachers differently than White parents (Mariñez-Lona & Quintana, 2009), it is unclear to what extent race might influence the predictive relationship between aspects of parent-school interactions and disruptive behavior problems. Thus, this study will examine …

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.

Local Squid Measurements In Extremely Overdoped La2-Xsrxcuo4 Thin Films, Chloe Herrera

Master's Theses

The overdoped regime of superconductivity in copper oxides may provide insight into the higher superconducting transition temperature and unique bordering phases. Using scanning Superconducting QUantum Interference Device (SQUID) microscopy, developments of superconductivity are spatially resolved in overdoped La2-xSrxCuO4 thin films. To further understand the local characteristics of the superconductor, SQUID measurements provide the London penetration depth, comparatively similar to global results.

The Impact Of A Novel Mobile-Friendly Nutrition Education Intervention On Dietary Patterns Among Calfresh Applicants, Kelly Brookshire Condron

Master's Theses

Background: College students experience food insecurity at a rate 3.5 times higher than the U.S. general population, affecting 43% of students. Furthermore, college students consume high amounts of ultra-processed products. NOVA, a food classification system, takes into account food processing and is thought to better fit the modern food environment.

Purpose: The purpose of this research project was to examine the impact of CalFresh enrollment on food security status. This study also evaluated the impact of two different nutrition education interventions (MyPlate and MyPlate+NOVA) on participants’ dietary habits and nutrition knowledge.

Methods: Food security, dietary habits, and nutrition knowledge were …

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 …