Digital Commons Network^™

Adaptive Sliding Mode Control Of Small Satellites In Formation For Distributed Beamforming Applications, Mason Earl Nixon

Dissertations

The rising popularity of small satellites over the past few decades has created a new boom in space, and, in particular, in low-Earth orbit. Exciting novel applications are being proposed that enable these small satellites to offer many advantages over their monolithic counterparts which can allow for augmentation, or possibly even replacement of more expensive and large alternatives. One particular enabling method is flying small satellites in formation for antenna array applications, which, through coupled dynamical modeling, can be facilitated through robust, nonlinear techniques of control. Thus, control of a perturbed satellite formation antenna array, with dual quaternion dynamics, is …

Nanomaterials In Theranostics : Therapeutics And Diagnosis Against Infectious Diseases, Unnatiben S. Patel

Dissertations

Nanomaterials-based hybrid nano therapy is gaining attraction as a promising way to treat intracellular bacterial infections. Gold-based nanomaterials have been widely used for biomedical applications such as photothermal therapy (PTT). This thesis discusses the development of a combination therapeutic approach that kills intracellular bacteria in conjunction with photothermal and antibiotic therapy using gold nanorod (GNR) based nano-assembly. This NIR laser-activated nano-assembly delivers antibiotics to the site of infection and offers PTT. The synergistic application of both therapies increases the efficacy of treatment. The protected delivery of antibiotics and their release in the proximity of the bacterial surface decreases off-target toxicity …

Accuracy Improvement Of Dynamic Sensors Measured Input Reconstruction Using Sliding Mode Observers, Rajesh Rayala Jayasheelareddy

Dissertations

Sensor dynamics adversely affect the accuracy of the obtained measurement by dynamically distorting the true value. The accuracy of the measurement may be further degraded by noise/exogenous perturbations. A sensor’s accuracy and performance are improved by reconstructing the true input signal of the sensor from the distorted measurement polluted by a corruption signal or exogenous inputs using Sliding mode and Higher-order sliding mode observer (SMO/HOSMO). The proposed technique is used to reconstruct/estimate a sensor’s true signal, thereby improving the transient response and driving the estimation steady state error to zero in finite time. The proposed SMO algorithm is based on …

The Universality Of Solubility Divergence Effects In Multicomponent Liquid Mixtures, Pauline R. Norris

Dissertations

Critical point effects have been observed in pure fluids, ferromagnets, substitutional alloys, and in binary liquid mixtures having a miscibility gap. That these systems are disparate, while the phenomena observed are similar, serves as the basis for the statement of the Principle of Critical Point Universality, which governs all critical behavior. The effect of the critical point on solute solubility is readily observed; the solubility diverges towards infinity in the critical region. One finds in the critical region that the slope (∂ln solubility/ ∂ (1/Temperature)) of a plot of ln solubility vs 1/Temperature diverges toward infinity if only one composition …

Discovery Of Counter Iads Swarming Autonomy Behaviors With Machine Learning, Joshua Robbins

Dissertations

Counter air-defense operations in highly contested airspaces pose significant risk to human life and scarce material resources, making it desirable to reduce the exposure of personnel to risk of loss of life and limb. Replacing human-piloted air platforms with a swarm of low-cost, unmanned systems in the contest for air superiority is therefore an area of intense interest. However, no doctrinal or tactical best practices for swarming combat yet exist. This dissertation documents research conducted to develop a systematical framework for discovery of counter-air defense tactics for unmanned aerial vehicles under control of a cognitive agent, using a reinforcement learning …

Modeling A Power-Generating Pulsed Nuclear Magnetic Nozzle, Nathan Schilling

Dissertations

Pulsed nuclear (fusion, fission, and fission/fusion hybrid) propulsion systems provide the potential for 10,000 s specific impulse and specific powers of 1000 W of jet power per kg of propulsion system mass. This enables a new class of medium thrust, high specific impulse capability, resulting in 1/3 of the trip times and significantly higher payload mass fractions compared with chemical propulsion performing the same mission. One of the challenges for pulsed nuclear propulsion is the conversion of an isotropic explosion to directed thrust, another challenge is the generation of electrical power needed to run these systems. To meet both of …

Investigating The Effect Of An Immersive Extracurricular Stem Program On Underrepresented And Disadvantaged High School Students' Self-Efficacy, Science Anxiety, And Career Aspirations, Nikki Mertz

Dissertations

This mixed methods study was designed to assess how an immersive extracurricular STEM program affected a student’s self-efficacy, science anxiety, and career aspirations. This study utilized the SIC-STEM survey to quantify student self-efficacy in science and the STEM Semantics survey to quantify student interest in STEM. Both surveys also assessed student interest in pursuing careers in STEM. The Science Anxiety survey was used to evaluate how student anxiety in science changed throughout the study. A subject matter survey was utilized to quantify student understanding and comprehension of an advanced science topic. Focus groups were used as the qualitative piece to …

Constraining Intrinsic Properties Of Gamma-Ray Bursts From Core-Collapse Supernovae And Neutron Star Mergers, Rachel Hamburg

Dissertations

Gamma-ray bursts (GRBs) are ultra-relativistic jets produced by either the core-collapse of massive, stripped envelope stars (i.e., "collapsars") or the merging of compact binary objects, such as neutron stars. GRBs are among the most energetic transients in the Universe, yet despite over 5 decades of study, a full description of their intrinsic energetics remains incomplete. This is primarily due to a combination of cosmological, relativistic, and observational effects that have impeded obtaining GRB redshift measurements and robustly associating GRBs with their progenitors. In this dissertation, I study source-frame properties of GRBs from collapsars and binary neutron star (BNS) mergers. In …

Functionalized Nanomaterials As Tailored Theranostics, Kavini M. Rathnayake

Dissertations

Theranostic nanoparticles are a type of biodegradable and biocompatible multifunctional nanosystems in combination with diagnostic and therapeutic capabilities for more specific and personalized disease management. However, difficulties still exist in engineering biocompatible theranostic nanoparticles with highly specific to intracellular bacteria and tumor. Development of nanoassemblies which can overcome these difficulties to achieve maximum therapeutic efficacy of the drugs will be discussed in this dissertation. Pseudomonas aeruginosa (PA) is an opportunistic pathogen, which causes serious lung infections in immunocompromised patients. Traditional oral intake of large quantities of small-molecule antibiotics to treat bacterial infections leads to off-target toxicity and development of drug-resistant …

Basic Psychological Needs Satisfaction, Autonomy Support, And Mindsets As Predictors Of Self-Regulation In University Online Learners, Ting Jin

Dissertations

Problem

In contrast to more traditional learning environments, it can be difficult to "see and hear" both the instructor and, more crucially, the students when engaging in online education. This has been one of the most common criticisms leveled against online education for a long time. The COVID-19 disruption and transformation of online learning in higher education underlines the fact that variance among online learners in terms of academic success and psychological well-being are determined by the level and quality of self-regulation. What is the degree of self-regulation among American university students who study online because of the COVID-19 pandemic's …

Impact Of Parent Presence On Stress In Infants In The Neonatal Intensive Care Unit, Susan M. Horner

Dissertations

The purpose of this study was to examine potential relationships between cumulative stress exposure in infants in neonatal intensive care units (NICU), as measured using a resting salivary cortisol level at NICU discharge, and the amount (hours per week) or frequency (days per week) of parent presence and skin-to-skin care (SSC). This descriptive study was conducted via a secondary analysis of a dataset representing 78 NICU families from a tertiary level NICU in the Midwest. Median length of stay was 33 days, and a resting salivary cortisol level collected at one month of age was used for infants not discharged …

Ensemble Approach To The Semantic Segmentation Of Satellite Images, Brendan Kent

Dissertations

Automatic classification and segmentation of land use land cover(LULC) is extremely important for understanding the relationship between humans and nature. Human pressures on the environment have drastically accelerated in the last decades, risking biodiversity and ecosystem services. Remote sensing via satellite imagery is an excellent tool to study LULC. Research has shown that deep learning encoder-decoder architectures have achieved worthy results in the area of LULC, however the application of an ensemble approach has not been well quantified. Studies have shown it to be useful in the area of medical imaging. Ensembling by pooling together predictions to produce better predictions …

An Analysis On Network Flow-Based Iot Botnet Detection Using Weka, Cian Porteous

Dissertations

Botnets pose a significant and growing risk to modern networks. Detection of botnets remains an important area of open research in order to prevent the proliferation of botnets and to mitigate the damage that can be caused by botnets that have already been established. Botnet detection can be broadly categorised into two main categories: signature-based detection and anomaly-based detection. This paper sets out to measure the accuracy, false-positive rate, and false-negative rate of four algorithms that are available in Weka for anomaly-based detection of a dataset of HTTP and IRC botnet data. The algorithms that were selected to detect botnets …

Evaluating The Performance Of Vision Transformer Architecture For Deepfake Image Classification, Devesan Govindasamy

Dissertations

Deepfake classification has seen some impressive results lately, with the experimentation of various deep learning methodologies, researchers were able to design some state-of-the art techniques. This study attempts to use an existing technology “Transformers” in the field of Natural Language Processing (NLP) which has been a de-facto standard in text processing for the purposes of Computer Vision. Transformers use a mechanism called “self-attention”, which is different from CNN and LSTM. This study uses a novel technique that considers images as 16x16 words (Dosovitskiy et al., 2021) to train a deep neural network with “self-attention” blocks to detect deepfakes. It creates …

An Investigation Of The Relationship Between Subjective Mental Workload And Objective Indicators Of User Activity, Greg Byrne

Dissertations

Whilst the concept of physical workload is intuitively understood and readily applicable in system design, the same cannot be said of mental workload (MWL), despite its importance in our increasingly technological society. Despite its origin in the mid 20th century, the very concept of ”mental workload” is still a topic of debate in the literature, although it can be loosely defined as “the amount of mental work necessary for a person to complete a task” (Miller, 1956; Longo, 2014). Several methods have been utilized to measure of MWL, including physiological methods such as neuro-imagery, performance-based metrics, and subjective measures via …

Evaluating The Performance Impact Of Fine-Tuning Optimization Strategies On Pre-Trained Distilbert Models Towards Hate Speech Detection In Social Media, Aidan Mcgovern

Dissertations

Hate speech can be defined as forms of expression that incite hatred or encourage violence towards a person or group based on race, religion, gender, or sexual orientation. Hate speech has gravitated towards social media as its primary platform, and its propagation represents profound risks to both the mental well-being and physical safety of targeted groups. Countermeasures to moderate hate speech face challenges due to the volumes of data generated in social media, leading companies, and the research community to evaluate methods to automate its detection. The emergence of BERT and other pre-trained transformer-based models for transfer learning in the …

Examining The Effects Of Disabilities On Vr Usage And Accessibility Issues For Persons With Disabilities, Sean Williams

Dissertations

Virtual Reality (VR) is an emerging technology that’s popularity has been increasing at a yearly rate. Despite this, concerns about the accessibility of VR devices are ever-growing as many users struggle to use the technology, especially users with disabilities. This study analyses how different types of disabilities affect how often a user uses VR and any associated re-occurring difficulties that are related to specific types of disability. To do this, a previous survey regarding VR accessibility run by Disability Visibility Project and ILMxLAB is examined. In this survey, 79 participants who identify as having a disability answered questions related to …

Development Of Aerospace Sliding Mode Control Toolbox : Relative Degree Approach With Resource Prospector Lander And Launch Vehicle Case Studies, Sai Susheel Praneeth Kode

Dissertations

Sliding mode control and observation techniques are widely used in aerospace applications, including aircraft, UAVs, launch vehicles, missile interceptors, and hypersonic missiles. This work is dedicated to developing a MATLAB based sliding mode controller design and simulation software toolbox that aims to support aerospace vehicle applications. An architecture of the proposed aerospace sliding mode control toolbox (SMC Aero) using the relative degree approach is developed. The created SMC Aero libraries include the design of first order sliding mode control (1-SMC), second order sliding mode control (2-SMC), higher order sliding mode (HOSM) control (either fixed gain or adaptive), as well as …

Adaptive Element Spacing Synthesis Technique In Phased Array Antennas, Tanzeela Mitha

Dissertations

Phased array antennas are widely used in a variety of military and civilian applications. For a given application, their radiation characteristics, such as the sidelobes, position of the nulls, and the main beam direction, need to be altered to enhance the array performance. To control these properties for a given requirement, the elements of phased array antennas need to be either properly excited or physically rearranged in different periodic and aperiodic configurations. However, once the position of the elements is fixed to control a single aspect of the generated pattern, it cannot simultaneously fulfill any other specification. To further alter …

Development Of An Explainability Scale To Evaluate Explainable Artificial Intelligence (Xai) Methods, Stephen Mccarthy

Dissertations

Explainable Artificial Intelligence (XAI) is an area of research that develops methods and techniques to make the results of artificial intelligence understood by humans. In recent years, there has been an increased demand for XAI methods to be developed due to model architectures getting more complicated and government regulations requiring transparency in machine learning models. With this increased demand has come an increased need for instruments to evaluate XAI methods. However, there are few, if none, valid and reliable instruments that take into account human opinion and cover all aspects of explainability. Therefore, this study developed an objective, human-centred questionnaire …

Selecting And Composing Cyberattack Component Models, Katia P. Maxwell

Dissertations

Modern society is increasingly reliant on computer systems for nearly all aspects of life, and the security of those systems has become an urgent concern. A research program that consists of several interconnected research projects in cybersecurity modeling has to date included the definition of a form of Petri nets extended with additional features specific to modeling cyberattacks, the automated generation of executable cyberattack component models from an attack pattern database, formal representation, and machine learning of attacker and defender strategies during cyberattacks, and the verification and validation of the component models. Because computer systems targeted in cyberattacks may have …

The Case For Alternate Media Requirement Expressions In Systems Engineering, Jason Kolligs

Dissertations

“Requirements” are often presented as a necessary, if not mandated, component or tool of the systems engineering process. Despite their place in engineering, low quality requirements are the first potential mistakes of an engineering project and their effects are potentially felt downstream in the form of increased costs and schedule overruns. Innovations to improve requirements engineering have historically omitted the requirement media. This research provides the rationale and process heuristics to include alternate media requirement expressions within systems engineering which shifts accountability to higher context requirement expressions that may require less cognitive load while decreasing effort and schedule thereby potentially …

Climate Change Adaptation And Retrofit Planning For Coastal Residential Buildings Subjected To Hurricanes, Babak Salarieh

Dissertations

Hurricanes are considered one of the most destructive and costly events, posing a significant threat to coastal communities and infrastructures across the Atlantic and Gulf coasts of the U.S. This devastating phenomenon is an extreme weather event, and its intensity is known to be impacted by environmental parameters such as sea surface temperature. Due to the predicted increase in the sea surface temperature associated with climate change projected, the intensity of future hurricanes is expected to increase substantially. Additionally, the continued population growth of coastal regions and the accompanying increase in the number of residential buildings is increasing the potential …

Reuse Considerations For Successful Complex Systems Integration, Logan Grumbach

Dissertations

As systems have become increasingly complex, engineers are relying on reuse of components and subsystems as a method to curb complexity. However, integrating these reuse components and subsystems have historically often resulted in catastrophic failures. Technical principles key to integration success and the role of reuse in these principles are not currently defined. The objective of this research is to, first, derive and validate a set of technical integration principles and subsequently to explore how incorporating reuse impacts integration success. This research uses historical system integration data and a combination of qualitative analysis techniques and quantitative techniques to draw conclusions …

And Still, I Rise: Madre Poderosas In The Pursuit Of Work-Life Justice In Educational Leadership Roles, Janet Oseguera-Valencia

Dissertations

The purpose of this mixed-methods study was to: (1) to describe and understand Latina leaders' experiences, perceptions, and challenges work-family conflict cause from an institutional, cultural, and individual lens; (2) and understand Latina leaders experiences, perceptions and helpful solutions work-life justice may create from an institutional, cultural, and individual lens. This study used quantitative data from a survey, and qualitative data from interviews. There were a total of sixty-three Latina leaders that participated in the survey and eighteen interviewed. The conceptual framework for this study centered around (1) a history of work-family conflict in educational leadership; (2) the complexities of …

An Investigation Of Mathematics Self-Efficacy, The Sources Of Mathematics Self-Efficacy, And Mathematics Achievement Among Primary School Students In Trinidad And Tobago, Ronald Sinanan

Dissertations

Purpose of the Study

This dissertation addressed two problems in the literature. Firstly, while many study findings have highlighted the critical role of self-efficacy in students' achievement, additional research was needed about the four hypothesized sources that influence the improvement of students' mathematics self-efficacy. Many studies on self-efficacy sources were conducted with measures not closely tied to social cognitive theory and have not demonstrated sufficient reliability. Using the Sources of Mathematics SelfEfficacy Scale, Usher and Pajares (2009) addressed this problem. They suggested several recommendations for future research (Usher & Pajares, 2008b, 2009), including exploring the validity of their scale in …

Isaac Newton As A Prophetic Interpreter, Kenneth Jørgensen

Dissertations

Throughout his life, Sir Isaac Newton was deeply dedicated to the science of decoding biblical apocalyptic writings. To understand and appreciate Newton's prophetic scheme, it will be advantagous to have a certain grasp of what sources and ideas might have influenced him. No comprehensive study before this one has helped us see Newton from that perspective. A survey of the development of canonical apocalyptic hermeneutic and interpretation, beginning before the time of Christ and ending with Newton, shows that four distinct systems of hermeneutics had developed by that time. Historicism was the earliest and the preferred system among Protestants until …

A Study Of Teacher Burnout In Private Seventh-Day Adventist And Public Schools In Trinidad/Tobago And Michigan, Usa, Carla Copeland-Joseph

Dissertations

Problem

Burnout as described by Maslach and Leiter (2007) is a syndrome involving psychological processes that result from Emotional Exhaustion, Depersonalization and diminished Personal Accomplishment in the workplace. It is represented as a stressful experience that is rooted in a person’s own interpretation of social relationships and needs. The aim of this study was to investigate teacher burnout and its interactions with individual factors (Gender, Years of Experience, Emotional Intelligence, Nationality), organizational factors (School Type, School Culture), and transactional factors (Technology Use, Teacher Self-Efficacy) for teachers in Trinidad and Tobago and the state of Michigan in the United States. The …

A Transformative Framework To Investigate The Influences Of Chineseness On Chinese International Students’ Learning Experiences On U.S. College Campuses, Wenjin Guo

Dissertations

This study applied a mixed-methods, social-justice approach to explore how Chinese international students interpret their success and/or challenges influenced by their Chinese forms of community cultural wealth in their academic learning at a predominately White Catholic university in the Midwest of the United States for over one year. I adopted a transformative paradigm to guide my study. Since the reviewed theoretical frameworks solely failed to form a profound comprehension of how Chineseness influenced Chinese international college students, I analyzed essential components of socio-cultural and critical race theories and created China as Method as the framework to guide my study.

This …

Supporting Latine Children’S Informal Engineering Learning And Spatial Thinking Through Tinkering And Storytelling, Diana Acosta

Dissertations

In the United States, the Latine community is the fastest growing minority group. Projections estimate that by the year 2060, they will represent 28% of the total population. Yet, Latines continue to be underrepresented and underserved in STEM fields and careers. Providing equitable informal STEM learning opportunities to young children may be a way to increase access and interest in STEM, to address the broader goal of increasing representation. Importantly, for these learning experiences to be truly equitable they must be meaningful and engage everyday cultural practices. Guided by a strengths-based approach, the current study examines how oral stories as …