Digital Commons Network^™

Numerical Methods For Predicting The Dynamic Crushing Response And Energy Absorption Of Composite Aluminum Honeycomb Sandwich Structures, Cody R. Volk

Master's Theses

Edgewise crushing responses of composite aluminum honeycomb sandwich structures were predicted using finite element analysis (FEA) software LS-DYNA by modeling the honeycomb as a material with anisotropic properties. The goal of the project was to develop a process for modeling the sandwich structure to rapidly iterate possible solutions for a safer workstation train table. Current workstation tables are too rigid and may cause injury or death in a head-on collision. Experimental compression tests were used to calibrate the aluminum honeycomb core with material type 26 (MAT 26, honeycomb). A published composite tensile test was used to validate the use of …

Bootstrapping Massively Multiplayer Online Role Playing Games, Mitchell Miller

Master's Theses

Massively Multiplayer Online Role Playing Games (MMORPGs) are a prominent genre in today's video game industry with the most popular MMORPGs generating billions of dollars in revenue and attracting millions of players. As they have grown, they have become a major target for both technological research and sociological research. In such research, it is nearly impossible to reach the same player scale from any self-made technology or sociological experiments. This greatly limits the amount of control and topics that can be explored. In an effort to make up a lacking or non-existent player-base for custom-made MMORPG research scenarios A.I. agents, …

The Effect Of Orientation On The Ignition Of Solids, David Morrisset

Master's Theses

The ignition of a solid is an inherently complex phenomenon influenced by heat and mass transport mechanisms that are, even to this day, not understood in entirety. In order to use ignition data in meaningful engineering application, significant simplifications have been made to the theory of ignition. The most common way to classify ignition is the use of material specific parameters such as such as ignition temperature (T_ig) and the critical heat flux for ignition (CHF). These parameters are determined through standardized testing of solid materials – however, the results of these tests are generally used in applications …

Smartphone-Tape Method For Calculating Body Segment Inertial Parameters For Analysis Of Pitching Arm Kinetics, Jay Sterner

Master's Theses

The objectives of this study were to (1) develop a non-invasive method (referred to as Smart Photo-Tape) to calculate participant-specific upper arm, forearm, and hand segment inertial properties (SIPs) (e.g. mass, center of mass, and radii of gyration) and (2) use those Smart Photo-Tape properties in inverse dynamics (ID) analyses to calculate injury-related pitching arm kinetics. Five 20- to 23- year-old baseball pitchers were photographed holding a baseball and analyzed using the Smart Photo-Tape method to obtain 3-D inertial properties for their upper arm, forearm, and hand. The upper arm and forearm segments were modelled as stacked elliptic cylinders and …

Towards Security And Privacy In Networked Medical Devices And Electronic Healthcare Systems, Isabel Jellen

Master's Theses

E-health is a growing eld which utilizes wireless sensor networks to enable access to effective and efficient healthcare services and provide patient monitoring to enable early detection and treatment of health conditions. Due to the proliferation of e-health systems, security and privacy have become critical issues in preventing data falsification, unauthorized access to the system, or eavesdropping on sensitive health data. Furthermore, due to the intrinsic limitations of many wireless medical devices, including low power and limited computational resources, security and device performance can be difficult to balance. Therefore, many current networked medical devices operate without basic security services such …

A Parametric Study Of Formation Flight Of A Wing Based On Prandtl's Bell-Shaped Lift Distribution, Kyle S. Lukacovic

Master's Theses

The bell-shaped lift distribution (BSLD) wing design methodology advanced by Ludwig Prandtl in 1932 was proposed as providing the minimum induced drag. This study used this method as the basis to analyze its characteristics in two wing formation flight. Of specific interest are the potential efficiency savings and the optimal positioning for formation flight. Additional comparison is made between BSLD wings and bird flight in formation.

This study utilized Computational Flow Dynamics (CFD) simulations on a geometric modeling of a BSLD wing, the Prandtl-D glider. The results were validated by modified equations published by Prandtl, by CFD modeling published by …

Design Of An Electrospray Thruster Power Processing And Digital Control Interface Unit, Douglas Howe

Master's Theses

Electrospray thrusters are low thrust, high specific impulse electric propulsion devices with applications in precision attitude control of space vehicles and efficient propulsion of small spacecraft platforms. These devices operate by electrostatically extracting particles from the surface of ionic liquid propellants and accelerating them away from the vehicle at high speed. Unlike more conventional propulsion technologies which only require electronics for control and regulation, electrospray thruster systems require extensive electronics to operate. The power processing unit (PPU) is a device used to produce the high voltage levels required to operate an electrospray thruster and to measure its operating parameters. The …

Fast Chirped Signals For A Tdma Ultrasonic Indoor Positioning System, Lauren M. Williams

Master's Theses

In this paper, a new concept for ultrasonic indoor positioning based on instantaneous frequency of ultrasonic signals is presented. Nonlinear phase characteristics of ultrasonic transducers introduce a frequency deviation in ultrasonic signals. By sweeping at very fast rates, a large spike in the deviation is introduced. The artefacts observable in instantaneous frequency estimations are highly localized and present an opportunity for accurate frequency detection. In order to be useful, the artefacts need to take place within the pulse and have sufficient magnitude for accurate processing. The system consists of a transducer transmitter and receiver pair, which have a center frequency …

Writing For Each Other: Dynamic Quest Generation Using In Session Player Behaviors In Mmorpg, Sean Christopher Mendonca

Master's Theses

Role-playing games (RPGs) rely on interesting and varied experiences to maintain player attention. These experiences are often provided through quests, which give players tasks that are used to advance stories or events unfolding in the game. Traditional quests in video games require very specific conditions to be met, and for participating members to advance them by carrying out pre-defined actions. These types of quests are generated with perfect knowledge of the game world and are able to force desired behaviors out of the relevant non-player characters (NPCs). This becomes a major issue in massive multiplayer online (MMO) when other players …

Initial Orbit Determination Error Analysis Of Low-Earth Orbit Rocket Body Debris And Feasibility Study For Debris Cataloguing From One Optical Facility, Kyle Stoker

Master's Theses

This paper is predicated on determining the effectiveness of angles-only initial orbit determination (IOD) methods when limited observational data is available for low-Earth orbit (LEO) rocket body debris. The analysis will be conducted with data obtained from Lockheed Martin Space’s Space Object Tracking (SpOT) facility, focusing on their observational data from 2018 that contains tracking of rocket body debris for less than one minute per overhead pass. After the IOD accuracies are better understood, a feasibility study will follow that investigates the possibility of cataloguing LEO orbital debris from a single optical observation facility with similar observational capabilities as that …

Design Of A Custom Wrist Brace That Can Be 3d Printed From A Three-Dimensional Scan, James D. Baldwin

Master's Theses

Current arm bracing and casting methods for distal forearm and wrist fractures can lead to varying negative medicinal affects such as tightness, skin breakdown and bacteria growth which can cause infection. This can be alleviated by a flexibly compliant and breathable design while keeping the arm and hand fixed at the wrist to promote proper wrist and forearm fracture healing. There have been attempts made to create a 3D printable brace from a three-dimensional scan but they do not account for full encapsulation of the wrist, removability without breaking the brace, nor for the brace being too tight and leading …

Simulating Particle Packing During Powder Spreading For Selective Laser Melted Additive Manufacturing Using The Discrete Element Method In Abaqus, Priscilla Ng

Master's Theses

Metal additive manufacturing allows for the rapid production of complex parts that are otherwise impractical using conventional subtractive manufacturing techniques. Applications for additive manufacturing span across a broad array of industries including aerospace, automotive, and medical, among many others. One metric of printing success is material properties, including part density. While there has been extensive research completed for the density of printed parts, there is little published work concerning powder packing density on the build plate associated with powder spreading.

In this thesis, a Discrete Element Method (DEM) model was created in Abaqus to simulate the spreading behavior of particles …

Analysis Of The Tidal Range In The Sacramento San Joaquin Delta From 1857 To Present, Elena Szlemp

Master's Theses

The Sacramento San Joaquin Delta has been highly altered by human activity since the mid-1800s from mining, agriculture, dredging, and urbanization. Did the resulting modifications to channel width, depth, and length alter tidal range in the Sacramento San Joaquin Delta?

In this study, archival tidal records were evaluated at many stations throughout the San Francisco Bay and Delta, with a focus on San Francisco, Rio Vista, Sacramento, and Stockton daily, monthly, and annual tidal ranges. Monthly and seasonally averaged tidal ranges were analyzed to determine seasonal changes. In addition, tidal range was compared to daily Delta discharge to consider the …

Investigation Of Experimental Variation Of Bovine Sphingomyelin As A Novel Ingredient For Ultraviolet Protection, Esther Chen

Master's Theses

Skin cancer is a prevalent disease that globally affects 2-3 million people per year [1]. This number is expected to grow tenfold as depletion of the ozone layer contributes to harsher rays reaching Earth’s surface [2]. A common way to protect against those ultraviolet waves is to apply sunscreen, however, recent reports call into question the safety of some active ingredients as they can enter through the skin into the bloodstream [3]. This thesis aims to investigate an alternative solution that uses bovine sphingomyelin (BSM) as photoprotective solution against UV irradiation.

In order to evaluate the effectiveness of BSM against …

Surface Modifications Of Reverse Osmosis Membranes For Removal Of Bromide And Reduction Of Fouling, Joseph Seo

Master's Theses

Reverse osmosis (RO) is widely used for water reuse and desalination. Although RO membranes are known for their high salt rejection and practical permeate flux, their performance can be impaired by fouling, and their removal of some disinfection byproducts and their precursors (e.g., bromide, N-Nitrosodimethylamine [NDMA]) does not meet drinking water standards. RO membrane modifications have been widely studied to overcome these limitations. In this research, RO membranes were grafted with cationic polymers to induce a positive charge on the RO membrane surface. This modification aimed at enhancing the rejection of negatively charged bromide ions by removing them from solution …

A Study Of The Design Of Adaptive Camber Winglets, Justin J. Rosescu

Master's Theses

A numerical study was conducted to determine the effect of changing the camber of a winglet on the efficiency of a wing in two distinct flight conditions. Camber was altered via a simple plain flap deflection in the winglet, which produced a constant camber change over the winglet span. Hinge points were located at 20%, 50% and 80% of the chord and the trailing edge was deflected between -5° and +5°. Analysis was performed using a combination of three-dimensional vortex lattice method and two-dimensional panel method to obtain aerodynamic forces for the entire wing, based on different winglet camber configurations. …

Attacking Computer Vision Models Using Occlusion Analysis To Create Physically Robust Adversarial Images, Jacobsen Loh

Master's Theses

Self-driving cars rely on their sense of sight to function effectively in chaotic and uncontrolled environments. Thanks to recent developments in computer vision, specifically convolutional neural networks, autonomous vehicles have developed the ability to see at or above human-level capabilities, which in turn has allowed for rapid advances in self-driving cars. Unfortunately, much like humans being confused by simple optical illusions, convolutional neural networks are susceptible to simple adversarial inputs. As there is no overlap between the optical illusions that fool humans and the adversarial examples that threaten convolutional neural networks, little is understood as to why these adversarial examples …

Pocket Rocket: A 1u+ Propulsion System Design To Enhance Cubesat Capabilities, James M. Harper

Master's Theses

The research presented provides an overview of a 1U+ form factor propulsion system design developed for the Cal Poly CubeSat Laboratory (CPCL). This design utilizes a Radiofrequency Electrothermal Thruster (RFET) called Pocket Rocket that can generate 9.30 m/s of delta-V with argon, and 20.2 ± 3 m/s of delta-V with xenon. Due to the demand for advanced mission capabilities in the CubeSat form factor, a need for micro-propulsion systems that can generate between 1 – 1500 m/s of delta-V are necessary.

By 2019, Pocket Rocket had been developed to a Technology Readiness Level (TRL) of 5 and ground tested in …

The Strawberry Rhizosphere Microbiome: Role On Plant Health And Nutrition, Eric Michael Boyd

Master's Theses

Microbial-root associations are important to help plants cope with abiotic and biotic stressors. Managing these interactions offers an opportunity for improving the efficiency and sustainability of agricultural production. By characterizing the bacterial and archaeal community (via 16S rRNA sequencing) associated with the bulk and rhizosphere soil of sixteen strawberry cultivars in two controlled field studies, we explored the relationships between the soil microbiome and plant resistance to two soilborne fungal pathogens of strawberry (Verticillium dahliae and Macrophomina phaseolina). Overall, the plants had a distinctive rhizosphere microbiome relative to the bulk soil, with higher abundances of known beneficial bacteria …

Quantitative And Qualitative Error Re-Analysis Of Tidal Datasets, Ernesto Andrew Ledezma

Master's Theses

Tidal data forms the basis for understanding and quantifying sea-level rise and tidal statistics. While quality assurance methods based upon spectral and harmonic analysis have been applied to individual tidal records, these methods have not been used to assess global tidal datasets. In this thesis, four west coast tidal records were examined using harmonic analysis methods to investigate uncertainty on a monthly averaged basis. Uncertainty was identified using a method that quantifies time lag as a linear regression of height difference between a predicted and measured tidal height and the predicted rate of change of tidal height. Errors identified through …

Cal Poly Pier Master Plan, Troy A. Lawson

Master's Theses

The Cal Poly Pier (Pier) Master/Facility Plan (FP) document provides the vision of the future for the Pier, a marine science research facility. The Plan facilitates project development and management of the Pier while meeting university and department research goals. Specifically, the FP document establishes goals and strategies to direct long-term development of the Pier, streamlines agency approval and permit requirements, provides context for pier management, and assists the permitting process for future development as it relates to regulatory permits and programmatic growth on the Cal Poly Pier to help meet goals of the Center for Coastal Marine Sciences (CCMS). …

Design Of A 5 Degree Of Freedom Kinematic Stage For The Dual Crystal Backlighter Imager Diagnostic, Nicholas Nguyen

Master's Theses

The National Ignition Facility (NIF) is home to the world’s most energetic laser. The facility is one of the leading centers in inertial confinement fusion (ICF) experiments to research and understand sustainable fusion energy. To fully document and understand the physics occurring during experiments, precise diagnostics are used for a wide range of purposes. One diagnostic, the crystal backlighter imager (CBI), allows for X-ray imaging of the target at late stages of its implosion.

The aim of this project was to increase the current capabilities of the CBI diagnostic with the addition of a second crystal. This thesis focuses on …

Mindfulness For Stress Reduction: Qualitative Analysis Of Perceptions From College Students And Mindfulness Instructors, Beth Marie Merlo

Master's Theses

Although mindfulness interventions with college students have yield positive results, many students are not continuing to engage after the interventions. This may be because very little research has been done to investigate the health behavior beliefs of college students in regard to mindfulness for stress reduction. The purpose of this investigation was to identify the most influential components of the Integrated Behavioral Model (IBM) that potentially assist with predicting college student participation in mindfulness activities for stress reduction. Interviews, informed by the IBM, were conducted with 20 current college students and 5 current mindfulness instructors working with college students. The …

Analysis Of Aquifer And Operational Conditions For Successful Soil Aquifer Treatment Of Treated Wastewater Via Synthesis Of Published Full-Scale And Laboratory-Scale Studies, Matthew I. Murray

Master's Theses

Soil aquifer treatment (SAT) of treated wastewater performance was evaluated across published full-scale and lab-scale studies developing insights on the aquifer and operational factors that affect SAT efficacy. The goal of this study was to develop a basis for predicting the contaminant removal capabilities of any given aquifer during managed recharge with treated wastewater.

Over 40 published SAT studies were reviewed and systematically compared to determine the influence of five major factors on contaminant removal performance: geologic composition, geochemical conditions, hydrogeological conditions, operational methods, and source water quality. Removal mechanisms for standard contaminants (dissolved and total organic carbon, nitrogen, and …

Analysis And Optimization Of Colorimetric Nanosensors For Rapid Detection Of Microbes In Water, Ruby A. Lang

Master's Theses

Access to safe water is a basic human right recognized by the United Nations General Assembly in 2010 (WHO, 2020). However, a least 2.2 billion people globally still are without safely managed water services meaning they use a drinking water source that can be contaminated with faeces (WHO, 2020). With such a pressing global health issue, it is clear that improvement to water systems is important and required in the Agenda 2030 Sustainable Development Goals (SDGs). However, to improve water systems and prove they are safe water sources, water quality testing must occur. A solution to this issue is the …

Altering An Epoxy-Amine Thermoset's Performance Through Varying Mix Ratios, Kiersten M. Smith

Master's Theses

Epoxy resins are used in a number of different industries and therefore have application-specific material requirements, from satellites that require materials that operate in space, to paints and coatings that require high scratch resistance and mechanical durability, to medical devices, designed to be in continuous contact with biological fluids. Commercial epoxy products come with manufacturer’s information explaining the epoxy properties and recommended preparation processing conditions, which may include epoxy resin to curing agent mix ratio (Part A : Part B), cure time, and cure temperature, for example. Due to proprietary reasons, it can be difficult to understand why these values …

Pier Portal, Alec W. Hardy

Master's Theses

The Pier Portal marine monitoring system is an internet controlled underwater camera that will enable students, researchers, and the general public the ability to monitor underwater marine life and ocean conditions. Installed at Cal Poly’s Center for Coastal Marine Science pier at Avila Beach, California, the camera can be commanded in real-time to raise or lower to any position between the top of the pier and the bottom of the ocean floor, while providing a live-stream video to the operator and general public. This thesis effort focused on the integration of the various subsystem components through software, and the development …

Planning For Pollinators, Encouraging Biodiversity For Agriculture Resiliency, Sebastian Brian Cardoza

Master's Theses

Pollinators are essential to food production globally. Without them, the production of food becomes increasingly difficult, time consuming, and costly. Unfortunately, due to the rapid changes to our earth's physical and climatic structure millions of species are becoming classified as threatened, endangered or extinct. Among these declining species are pollinating insects such as Aphis mellifera (honeybee) and other native species. This is due to a phenomenon known as colony collapse disorder (CCD) and other native bees. The decline indicates that the future habitability of earth may be in jeopardy. The solution to this crisis is to expand the habitat of …

Analysis And Design Of An Off-Grid Residential Power System, Christopher Rotsios

Master's Theses

This thesis aims to provide a recommended power system design for optimal efficiency, reliability, and cost in off-grid applications. The power system examined in this project is a residence in an off-grid community called Quail Springs that generates its energy from roof mounted solar panels. The existing system was analyzed to see what equipment can remain, what needs to be upsized, and what needs to be added to the system. Two power systems are considered for the residence: a fully AC power system and a hybrid AC/DC power system. Simulations were run in PSCAD to compare the efficiencies of the …

Flexible Fault Tolerance For The Robot Operating System, Sukhman S. Marok

Master's Theses

The introduction of autonomous vehicles has the potential to reduce the number of accidents and save countless lives. These benefits can only be realized if autonomous vehicles can prove to be safer than human drivers. There is a large amount of active research around developing robust algorithms for all parts of the autonomous vehicle stack including sensing, localization, mapping, perception, prediction, planning, and control. Additionally, some of these research projects have involved the use of the Robot Operating System (ROS). However, another key aspect of realizing an autonomous vehicle is a fault-tolerant design that can ensure the safe operation of …