Digital Commons Network^™

Nondestructive Evaluation (Nde) Of Additively Manufactured Metal (Amm) Parts Using Ultrasonic Testing (Ut), Austin M. Thomas

Master's Theses

Additive manufacturing is a category of emerging manufacturing processes that have applications in creating metal components with high value and complexity. The adoption of these parts is limited by the lack of fully developed nondestructive techniques for identifying internal defects. The use of ultrasonic testing for detecting and measuring internal features in additively manufactured metal parts is investigated. A low-cost ultrasonic immersion testing system was designed, constructed, and validated for the inspection of an additively manufactured titanium specimen with artificial defects as well as other metal artifacts. An ultrasound calibration block was additively manufactured from stainless steel type 316L and …

Operational Decision-Making In Healthcare Using Control Charts, Rohan More

Master's Theses

The primary objective of this thesis was to design a framework supplemented with guidelines for the healthcare managers to select an appropriate type of control chart for operational decision-making. A systematic literature review was conducted to gauge the extent to which control charts were being used in a healthcare setting for clinical decision making and operational decision-making purposes. The findings showed that the application of control charts was almost equal for the clinical decision-making sector and the operational decision-making sector. On further analysis, the ability of control charts to function as a standalone tool was affirmed by the vast majority …

Personality And Mood For Non-Player Characters: A Method For Behavior Simulation In A Maze Environment, Noah L. Paige

Master's Theses

When it comes to video games, immersion is key. All types of games aim to keep the player immersed in some form or another. A common aspect of the immersive world in most role-playing games -- but not exclusive to the genre -- is the non-playable character (NPC). At their best, NPCs play an integral role to the sense of immersion the player feels by behaving in a way that feels believable and fits within the world of the game. However, due to lack of innovation in this area of video games, at their worst NPCs can jar the player …

A Novel Method To Commercialize Medical Devices Initially Developed At California Polytechnic State University San Luis Obispo, Christina Grigorian

Master's Theses

California Polytechnic State University, San Luis Obispo is a university that encourages students to approach learning hands-on. As such, there is cutting-edge technology being developed by students in all departments on campus. Being that the university possesses an outstanding biomedical engineering department, there are groundbreaking medical devices that students are creating at Cal Poly SLO. These are devices that can better the lives of individuals suffering from ailments or fulfill needs in the medical industry. Subsequently, it is vital that these devices make it out of campus laboratories and into the hands of consumers. In order to move a product …

Understanding The Effects Of Long-Duration Spaceflight On Fracture Risk In The Human Femur Using Finite Element Analysis, Keyanna Brielle Henderson

Master's Theses

Long-duration spaceflight has been shown to have significant, lasting effects on the bone strength of astronauts and to contribute to age-related complications later in life. The microgravity environment of space causes a decrease in daily mechanical loading, which signals a state of disuse to bone cells. This affects the bone remodeling process, which is responsible for maintaining bone mass, causing an increase in damage and a decrease in density. This leads to bone fragility and decreases overall strength, posing a risk for fracture. However, there is little information pertaining to the timeline of bone loss and subsequent fracture risk.

This …

Envrment: Investigating Experience In A Virtual User-Composed Environment, Matthew Key

Master's Theses

Virtual Reality is a technology that has long held society's interest, but has only recently began to reach a critical mass of everyday consumers. The idea of modern VR can be traced back decades, but because of the limitations of the technology (both hardware and software), we are only now exploring its potential. At present, VR can be used for tele-surgery, PTSD therapy, social training, professional meetings, conferences, and much more. It is no longer just an expensive gimmick to go on a momentary field trip; it is a tool, and as with the automobile, personal computer, and smartphone, it …

Study Of Plants Used Against Infections By California Native American Tribes, Maria J. Rojas

Master's Theses

The objectives of this research were to evaluate the antibacterial activity and to determine the chemical composition of a list of medicinal plants used by Native Americans in California. Artemisia californica, Mimulus aurantiacus, Equisetum telmateia, Equisetum hyemale, and Marah fabacea were selected from a list of plants reported as having been used for ailments related to infections by tribes located in California. The extracts obtained through steam distillation from E. telmateia, E. hyemale and M. fabacea were assayed for in vitro antibacterial activity against 16 Gram-negative and 6 Gram-positive bacteria using disk diffusion assays and measuring the diameters of inhibition …

Investigation On The Use Of Small Aperture Telescopes For Leo Satellite Orbit Determination, Luis R. Curiel Iii

Master's Theses

The following thesis regards the use of small aperture telescopes for space domain awareness efforts. The rapidly populating space domain was motivation for the development of a new operation scheme to conduct space domain awareness feasibility studies using small telescopes. Two 14-inch Schmidt-Cassegrain Telescopes at the California Polytechnic State University and the Air Force Research Lab in Kirtland AFB, NM, in conjunction with a dedicated CCD camera and a commercial DSLR camera, were utilized to conduct optical observations on satellites in Earth orbit.

Satellites were imaged during August 2019, and from January 2020 to March 2020, resulting in the collection …

Field Testing The Effects Of Low Reynolds Number On The Power Performance Of The Cal Poly Wind Power Research Center Small Wind Turbine, John B. Cunningham

Master's Theses

This thesis report investigates the effects of low Reynolds number on the power performance of a 3.74 m diameter horizontal axis wind turbine. The small wind turbine was field tested at the Cal Poly Wind Power Research Center to acquire its coefficient of performance, C­_p, vs. tip speed ratio, λ, characteristics. A description of both the wind turbine and test setup are provided. Data filtration and processing techniques were developed to ensure a valid method to analyze and characterize wind power measurements taken in a highly variable environment. The test results demonstrated a significant drop in the …

Real-Time Body Tracking And Projection Mapping In The Interactive Arts, Sydney Baroya

Master's Theses

Projection mapping, a subtopic of augmented reality, displays computer-generated light visualizations from projectors onto the real environment. A challenge for projection mapping in performing interactive arts is dynamic body movements. Accuracy and speed are key components for an immersive application of body projection mapping and dependent on scanning and processing time.

This thesis presents a novel technique to achieve real-time body projection mapping utilizing a state of the art body tracking device, Microsoft’s Azure Kinect DK, by using an array of trackers for error minimization and movement prediction. The device's Sensor and Bodytracking SDKs allow multiple device synchronization. We combine …

Design And Validation Of An Led-Based Solar Simulator For Solar Cell And Thermal Testing, Matthew Gunther

Master's Theses

An LED-based solar simulator has been designed, constructed, and qualified under ASTM standards for use in the Cal Poly Space Environments Laboratory. The availability of this simulator will enhance the capability of undergraduate students to evaluate solar cell and thermal coating performance, and offers further research opportunities. The requirements of ASTM E927-19 for solar simulators intended for photovoltaic cell testing were used primarily, supplemented by information from ASTM E491-73 for solar simulators intended for spacecraft thermal vacuum testing. Three main criteria were identified as design goals - spectral match ratio, spatial non-uniformity, and temporal instability. An electrical design for an …

Missing In Action: Locating The Body In Interdisciplinary Studies, Ann Lenore Moradian

Master's Theses

This research project relied on the use of interdisciplinary literature, surveys and interviews to explore the prevalence of the human body and its movement across a variety of disciplines other than movement-based practices, and also to explore perspectives of movement experts regarding the knowledge, skills, and capacities they believed might be related to their practice-based work. In other words, what do movement practitioners and movement experts know, and who cares? The materials gathered were analyzed with the aim of understanding the range of possibilities for future work, and identifying areas of potential discourse, engagement, or collaboration across disciplines. The outcomes …

Dataset And Evaluation Of Self-Supervised Learning For Panoramic Depth Estimation, Ryan Nett

Master's Theses

Depth detection is a very common computer vision problem. It shows up primarily in robotics, automation, or 3D visualization domains, as it is essential for converting images to point clouds. One of the poster child applications is self driving cars. Currently, the best methods for depth detection are either very expensive, like LIDAR, or require precise calibration, like stereo cameras. These costs have given rise to attempts to detect depth from a monocular camera (a single camera). While this is possible, it is harder than LIDAR or stereo methods since depth can't be measured from monocular images, it has to …

With A Little Help From My Friends: Determining The Role Of Physical Activity And Belonging In Retention Of First-Year University Students, Bryson Kelly

Master's Theses

There exists an issue facing colleges and universities across the United States. Roughly 29% of first-year students do not return for their second year of school. Previous research has shown a significant relationship between a student’s sense of belonging or fit within the university and their decision to continue enrollment (retention). Physical activity has also been shown to have a significant relationship with a sense of belonging. Therefore, the purpose of the present study was to determine if physical activity and sense of belonging predict retention of university students from their first year to their second year using a Relationships …

Educational Leadership Can Dance: A Deeper Look Into The Efficiency Behind Evaluations Of Dance Educators, Helen Brown

Master's Theses

The purpose of this study was to provide information on the issue of dance educator evaluation’s level of integrity, potential biases, and efficiency. Further, this study also acts as a review of current evaluation systems within public schools across the United States. The researcher received information about the evaluation systems from eleven dance educators in addition to how nine educational leaders evaluate their dance educators, along with one educational leader’s personal insight into their respective evaluation process. The research instruments utilized were online surveys and interviews. Both the surveys and interview responses were analyzed both quantitatively and qualitatively, depending on …

Contribution Of Submarine Groundwater Discharge To Select Biogeochemical Fluxes In St. Louis Bay, Mississippi, Haley Spaid

Master's Theses

This thesis assesses the role of submarine groundwater discharge (SGD) in St. Louis Bay, Mississippi. Located along the northern Gulf of Mexico, St. Louis Bay (SLB) is a semi-enclosed bay that is important to the local area for recreation and tourism. SGD is the movement of any water into the water column across the sediment-water interface. In coastal environments, SGD can be a source of a variety of substances including nutrients and pollutants. In this study, a steady state mass balance approach was used to quantify SGD flux for SLB using ²²³Ra, ²²⁴Ra, and Ba. Using the water …

Hypersonic Heat Transfer Load Analysis In Star-Ccm+, Robert Comstock

Master's Theses

This thesis investigates the capabilities of STAR-CCM+, a Computational Fluid Dynamics (CFD) software owned by Siemens, in predicting hypersonic heat transfer loads on forward-facing surfaces. Results show that STAR-CCM+ predicted peak heat transfer loads within +/- 20% of experimental data on the leading edge of a delta wing design from the X-20 Dyna-Soar program with 73^o of sweep. Steady-state laminar simulations were run as replications of wind tunnel tests documented in NASA CR-535, a NASA technical report that measured and studied the hypersonic pressure and heat transfer loads on preliminary X- 20 wing designs across a wide range of …

Comparison Of Classification Algorithms And Undersampling Methods On Employee Churn Prediction: A Case Study Of A Tech Company, Heather Cooper

Master's Theses

Churn prediction is a common data mining problem that many companies face across industries. More commonly, customer churn has been studied extensively within the telecommunications industry where there is low customer retention due to high market competition. Similar to customer churn, employee churn is very costly to a company and by not deploying proper risk mitigation strategies, profits cannot be maximized, and valuable employees may leave the company. The cost to replace an employee is exponentially higher than finding a replacement, so it is in any company’s best interest to prioritize employee retention.

This research combines machine learning techniques with …

Barrel Support Fabrication And Arcing Reduction In Railguns, Eric Venenga

Master's Theses

Collisions with orbital debris present risks to spacecraft and astronauts. Orbital debris is capable of generating hypervelocity impacts, which can generate system threatening damage. In order to protect assets a means of defending against these types of impacts must be developed. In order to evaluate these methods prior to launch, ground based testing systems must also be developed.Cal Poly’s Electromagnetic Railgun program began in 2011 with the idea of creating a system capable generating hypervelocity impacts in a laboratory setting. Due to a loss of efficiency due to arcing in the barrel and a lack of side supports capable of …

Analysis Of Electroanatomic Mapping System Accuracy Using X-Ray Reconstruction Of Electrode Locations In A Porcine Animal Model, Hana Boudlali

Master's Theses

Fluoroscopy is considered the gold standard for locating catheters during cardiac electrophysiology (EP) procedures. However, fluoroscopy emits ionizing radiation which can lead to adverse health effects when exposed to in high doses (World Health Organization, 2016). Electroanatomic mapping (EAM) systems display the three-dimensional location of EP catheters and measure the local electrical activity of the heart. They can minimize a physician’s reliance on fluoroscopy and can help reduce radiation exposure during a case (Casella, 2011).

EAM systems are diagnostic medical devices that inform the placement of ablation therapy and must accurately locate catheters to be deemed safe. Test methods to …

A Protocol For Achieving Adherent Cell Culture Within A Microfluidic Device, Tarra Danielle Sanders

Master's Theses

The goal of this study is to design a protocol for the adherent cell culture within a novel microfluidic device. Microscale cell culture protocols were developed for loading cells using poly-L-lysine to enhance adherent cell culture of murine derived NIH 3T3 fibroblasts. This work sought to develop a method for adherent microculture by examining various sterilization, surface treatment, and seeding techniques. Using a vacuum suction loading technique, air plasma treatment and a poly-L-lysine surface treatment adherent cell culture was observed within the device. The work presented here is part of a collaborative effort that aims to develop protocols for the …

Spacecraft Trajectory Optimization Suite (Stops): Design And Optimization Of Multiple Gravity-Assist Low-Thrust (Mgalt) Trajectories Using Modern Optimization Techniques, Michael G. Malloy

Master's Theses

The information presented in the thesis is a continuation of the Spacecraft Trajectory Optimization Suite (STOpS). This suite was originally designed and developed by Timothy Fitzgerald and further developed by Shane Sheehan, both graduate students at California Polytechnic State University, San Luis Obispo. Spacecraft utilizing low-thrust transfers are becoming more and more common due to their efficiency on interplanetary trajectories, and as such, finding the most optimal trajectory between two planets is something of interest. The version of STOpS presented in this thesis uses Multiple Gravity-Assist Low-Thrust (MGALT) trajectories paired with the island model paradigm to accomplish this goal. The …

B-Plane Targeting With The Spacecraft Trajectory Optimization Suite, Jared Graef

Master's Theses

In interplanetary trajectory applications, it is common to design arrival trajectories based on B-plane target values. This targeting scheme, B-plane targeting, allows for specific target orbits to be obtained during mission design. A primary objective of this work was to implement B-plane targeting into the Spacecraft Trajectory Optimization Suite (STOpS). This work was based on the previous versions of STOpS done by Fitzgerald and Sheehan, however STOpS was redeveloped from MATLAB to python. This updated version of STOpS implements 3-dimensional computation, departure and arrival orbital phase modeling with patched conics, B-plane targeting, and a trajectory correction maneuver. The optimization process …

Incorporating Shear Resistance Into Debris Flow Triggering Model Statistics, Noah J. Lyman

Master's Theses

Several regions of the Western United States utilize statistical binary classification models to predict and manage debris flow initiation probability after wildfires. As the occurrence of wildfires and large intensity rainfall events increase, so has the frequency in which development occurs in the steep and mountainous terrain where these events arise. This resulting intersection brings with it an increasing need to derive improved results from existing models, or develop new models, to reduce the economic and human impacts that debris flows may bring. Any development or change to these models could also theoretically increase the ease of collection, processing, and …

Impact Of Soil Properties On Removal Of Emerging Contaminants From Wastewater Effluent During Soil Aquifer Treatment, Lauren N. Riley

Master's Theses

This study evaluates soil properties that impact the effectiveness of soil aquifer treatment (SAT) as a polishing step to the remove two classes of ECs from wastewater effluent: pharmaceuticals and personal care products (PPCPs), and engineering nanomaterials (ENMs). In recent years, it has been determined that elevated levels of emerging contaminants (ECs) are being released into the environment with wastewater effluent. ECs are proven to cause adverse environmental and health effects as a result of long-term exposure. It is important to evaluate sustainable solutions to improve the current methods of wastewater treatment to address these ECs.

Soil aquifer treatment (SAT) …

Finite Element Analysis Of Total Knee Arthroplasty, Sean Yueh

Master's Theses

The total knee arthroplasty (TKA) has become one of the most successful procedures in all of medicine, with an average of over 966,000 operations performed a year. Since its introduction in 1968, the TKA’s surgical process and implant designs have continuously been improved to increase survivability. However, the need for a revision TKA – due to aseptic loosening – continues to be a problematic aspect of the procedure. Stress shielding induced by different design parameters of the implant has generated controversy in the determination of an ideal configuration. The purpose of this study is to investigate how implant design parameters …

Simulation Of An Sp8t 18 Ghz Rf Switch Using Smt Pin Diodes, Andre De Souza Vigano

Master's Theses

Radio frequency (RF) and microwave switches are widely used in several different applications including radar, measurement systems, telecommunications, and other areas. An RF switch can control a radar’s transmit vs. receive mode, select the operating band, or direct an RF signal to different paths. In this study, a single pole eight throw (SP8T) switch using only Surface Mount (SMT) components is designed and simulated in Keysight’s Advanced Design System (ADS). Single pole eight throw is defined as one input and eight possible outputs. A star network configuration with series-shunt PIN diode switches is used to create the 8-way RF switch. …

Eelgrass (Zostera Marina) Population Decline In Morro Bay, Ca: A Meta-Analysis Of Herbicide Application In San Luis Obispo County And Morro Bay Watershed, Tyler King Sinnott

Master's Theses

The endemic eelgrass (Zostera marina) community of Morro Bay Estuary, located on the central coast of California, has experienced an estimated decline of 95% in occupied area (reduction of 344 acres to 20 acres) from 2008 to 2017 for reasons that are not yet definitively clear. One possible driver of degradation that has yet to be investigated is the role of herbicides from agricultural fields in the watershed that feeds into the estuary. Thus, the primary research goal of this project was to better understand temporal and spatial trends of herbicide use within the context of San Luis …

An Exploratory Study Of Pulse Width And Delta Sigma Modulators, Logan B. Penrod

Master's Theses

This paper explores the noise shaping and noise producing qualities of Delta-Sigma Modulators (DSM) and Pulse-Width Modulators (PWM). DSM has long been dominant in the Delta Sigma Analog-to-Digital Converter (DSADC) as a noise-shaped quantizer and time discretizer, while PWM, with a similar self oscillating structure, has seen use in Class D Power Amplifiers, performing a similar function. It has been shown that the PWM in Class D Amplifiers outperforms the DSM [1], but could this advantage be used in DSADC use-cases? LTSpice simulation and printed circuit board implementation and test are used to present data on four variations of these …

Video Based Automatic Speech Recognition Using Neural Networks, Alvin Lin

Master's Theses

Neural network approaches have become popular in the field of automatic speech recognition (ASR). Most ASR methods use audio data to classify words. Lip reading ASR techniques utilize only video data, which compensates for noisy environments where audio may be compromised. A comprehensive approach, including the vetting of datasets and development of a preprocessing chain, to video-based ASR is developed. This approach will be based on neural networks, namely 3D convolutional neural networks (3D-CNN) and Long short-term memory (LSTM). These types of neural networks are designed to take in temporal data such as videos. Various combinations of different neural network …