Digital Commons Network^™

Signal Integrity Analysis And Electromagnetic Inteference Modeling For Autonomous Vehicles, Yuandong Guo

Doctoral Dissertations

"An autonomous vehicle (AV) may employ various sensors to detect the environment, and the hardware for self-driving should be able to process large volume of sensor data and make real-time decisions. For signal integrity (SI), both the bandwidths and data rates of the high-speed channels should meet the requirements. The electromagnetic interference (EMI) noise may become a major concern with the ever-increasing number of electric modules. This research focuses on both SI analysis and EMI modeling for AVs. The first topic is accurate and broadband three-phase motor modeling. The novel modeling methodology for a typical three-phase motor is presented, using …

Secure And Efficient Information Management In Delay(Disruption) Tolerant Network, Shudip Datta

Doctoral Dissertations

"In environments like international military coalitions on the battlefield or multi-party relief work in a disaster zone, multiple teams are deployed to serve different mission goals by the command-and-control center (CC). They may need to survey damages and send information to the CC for situational awareness and also transfer messages to each other for mission purposes. However, due to the damaged network infrastructure in the emergency, nodes need to relay messages using the store and forward paradigm, also called Delay-tolerant Networks (DTNs). In DTN, the limited bandwidth, energy, and contacts among the nodes, and their interdependency impose several challenges such …

Computational Fluid Dynamics Techniques For Multiphase Flow Systems, Jose Sebastian Uribe Lopez

Doctoral Dissertations

"Mathematical modelling of multiphase flow systems has been a major and persistent challenge over the last decades. Vast attempts to obtain predictive models can be found reported in literature, where major advances can be recognized in recent years, paired to enhancements in computer science and engineering. Notwithstanding, universally valid models with a mechanistic development are far from being achieved. The current status of modelling any multiphase flow system relies on the model order reduction of purely theoretical models. Such reductions and simplifications become the source of deviations in the predictions of the experimentally measured parameters and will constrain the applicability …

Persistent Stealthy Attacks And Their Detection In Large Distributed Cyber-Physical Systems, Simon Bech Thougaard

Doctoral Dissertations

"Cyber-Physical Systems (CPS) are increasingly targeted by attackers using a wide and evolving array of methods. When these systems are distributed, every node represents a potential vulnerability, and secure system design must take this into account. Distributed CPSs also have the potential to better detect and handle attacks, by leveraging redundancies of physical measurements between adjacent nodes. The main purpose of this research is to determine the conditions that render a distributed CPS more resistant to attacks, and the conditions that render it more vulnerable. The work is centered around two separate applications: The Smart Grid and Autonomous Drone Swarms. …

Accuracy Improvement Of Cable Harness Modeling & Analytical Modeling Of Multi-Reflections In High-Speed Signal Channels, Muqi Ouyang

Doctoral Dissertations

"Cable harnesses are widely used in modern vehicles to power electric systems locating at different locations throughout the vehicle and to establish signal channels for data communications between these systems. Generally, a cable harness consists of multiple wires and its geometry can be very complicated, making full-wave modeling and simulation approaches computational resource-intensive. To cut down the computational effort, the hybrid multiconductor transmission-line (MTL) method has been developed, and the generalized MTL (GMTL) method and the multiple scattering (MS) method have been developed to improve the accuracy of the hybrid MTL method. In this research, the convergence issue in the …

Theoretical Determination Of The Yield Curve For Unsaturated Soils, Sara Fayek

Doctoral Dissertations

"An important step to developing a good understanding of the behavior of unsaturated soils is to adopt a formal and simple constitutive framework and to conduct high-quality and short-time experiments. Barcelona Basic Model (BBM) was the first elastoplastic constitutive model for unsaturated soils. The yield curve, which separates the elastic region from the elastoplastic region, is an important aspect of constitutive modeling for unsaturated soils. Most concepts for unsaturated soils were developed based upon the results from suction-controlled triaxial (SCTX) tests. Though, the SCTX tests on unsaturated soils are costly, time-consuming, and laborious, and their results are questionable. This study …

Strain And Temperature Measurement From Distributed Fiber Optic Sensors In Performance-Based Fire Engineering, Yanping Zhu

Doctoral Dissertations

"Strain and temperature measurement of steel and concrete structures under fires is critical to the understanding of structural performance yet historically challenging due to a significant gap in measurement science. This Ph.D. study characterizes in six parts low-cost distributed fiber optic sensors and applies them to strain, and temperature measurements based on Rayleigh and Brillouin light scattering. The first part aims to quantify the Rayleigh scattering based measurement accuracy of distributed fiber optic sensors under a heating-holding load protocol and characterize the effect of polymer coating on the sensors as the polymer softens and melts at elevated temperatures. The second …

Multi-Stage Multi-Market Optimal Bidding Strategy In Electricity Markets, Hossein Mehdipourpicha

Doctoral Dissertations

"Restructuring of power industry created the competitive situations for different MPs through designing appropriate electricity markets. Typically, in pool-based electricity markets, MPs submit their offers, and ISO clears the market and notifies MPs of the cleared power amounts and market prices. In this situation, designing an effective bidding strategy for MPs who seek to maximize their profits has thus become one of the crucial yet difficult tasks that still need further exploration. The majority of recent studies overlooked this problem for the purely financial players. Therefore, designing an efficient strategy for virtual bidder in the pool-based electricity markets is studied …

Laterally Heterogeneous Seismic Anisotropy Investigated By Shear Wave Splitting Analyses, Yan Jia

Doctoral Dissertations

"Numerous geophysical studies suggest that seismic anisotropy is a nearly ubiquitous property of the Earth’s crust and upper mantle. In this study, we utilize the shear wave splitting technique to investigate the piercing-point-dependent azimuthal anisotropy beneath the northeastern edge of the Sichuan Basin in central China, and the spatial and temporal variations of anisotropy near the 2019 M7.1 Ridgecrest earthquake in California, respectively. A clear back azimuthal dependence of the splitting parameters and the lack of a 90° or 180° periodicity of azimuthal variation in the observed fast orientations provide strong evidence for the existence of piercing-point-dependent anisotropy beneath the …

Using Computational Methods To Optimize High Heat Flux Component Thermal Performance In Magnetic Confinement Fusion Reactor Research, Monica Gehrig

Doctoral Dissertations

"Heat transfer enhancement by means of internally modified geometries in tubes and channels is an important mechanism to improve the survivability of components in extreme high-heat flux environments. Various features such as ribs and fins are studied using computational fluid dynamics in both uniform and one-sided heating in tubes and rectangular channels respectively to determine the most effective geometries across a variety of different flow and heating conditions. This work examines heat transfer enhancement and rib geometry optimization to support experimental research for nuclear fusion applications. The project begins by designing and analyzing test sections supporting a helium flow loop …

Influences Of The Internal Residual On Combustion Instabilities In The Misfire And Partial Burn Regimes Of A Dilute Spark-Ignition Engine, Rachel Inez Stiffler

Doctoral Dissertations

"Dilution in spark-ignition (SI) engines can improve fuel consumption and reduce emissions; however, increased levels of dilution either from excess oxidizer or exhaust gas recirculation (EGR) causes combustion to become more strained and cycle-to-cycle variations increase. At high levels of dilution incomplete combustion events (i.e. misfires and partial burns) start to occur, which cause combustion instabilities and eventually a dilute limit is reached. It is known the combustion instabilities seen are primarily due to the feed-forward mechanism present in the residual gases, but it is still unknown what about the residual is influencing the dynamics under high levels of dilution …

Mantle Flow And Transition Zone Discontinuities Beneath The Carribean Plate: Constraints From Shear Wave Splitting And Receiver Function Analyses, Tu Xue

Doctoral Dissertations

"Azimuthal anisotropy quantified by teleseismic SKS, SKKS, PKS (“XKS”) and local S wave splitting parameters is used to investigate lithospheric deformation and asthenospheric flow beneath the boundary zone of the North American and Caribbean plates and adjacent areas. A total of 4915 XKS and 1202 pairs of local S wave splitting parameters were obtained at 24 broad band seismic stations. The XKS observations can be divided into two groups based on the spatial distribution of the resulting fast polarization orientations. Those observed on the Caribbean Plate are mostly WNW-ESE which are roughly trench-parallel. In contrast, the fast orientations observed on …

Application Of Machine Learning In Geophysics: Ranking Teleseismic Shear Wave Splitting Measurements And Classifying Different Types Of Earthquakes, Yanwei Zhang

Doctoral Dissertations

"During the past decades, applications of Machine Learning have been explosively developed to solve various academic and industrial problems, and over-human performance has been shown in diverse areas. In geophysical research, Machine Learning, especially Convolutional Neural Network (CNN), has been applied in numerous studies and demonstrated considerable potential. In this study, we applied CNN to solve two geophysical problems, ranking teleseismic shear splitting (SWS) measurements and classifying different types of earthquakes.

For ranking teleseismic SWS measurements, we utilized a CNN-based method to automatically select reliable SWS measurements. The CNN was trained by human-verified teleseismic SWS measurements and tested using synthetic …

Disorder Effects In Frustrated Magnets And Absorbing State Transitions, Xuecheng Ye

Doctoral Dissertations

"Correlation, topology, and disorder can fundamentally affect the properties of interacting many-particle systems. After a short introduction which covers the basic concepts of phase transitions and scaling as well as the physics of Josephson junctions, the dissertation focuses on three separate projects.

The first project is motivated by the stripe and nematic phases observed e.g. in cuprate superconductors and iron pnictides. To understand the effects of disorder on such phases, we have investigated the behavior of the diluted J₁-J₂ Ising model. Spinless impurities generate a random-field disorder for the spin-density (stripe) order parameter, which destroys the stripe …

Resistivity Imaging Of Prominent Seepage Pathways In Karst Terrain, Abdullah Hadi Zaid Alhaj

Doctoral Dissertations

"An integrated research approach was conducted to evaluate subsurface karstic conditions in Greene County, southwestern Missouri. Electrical resistivity tomography (ERT) was employed to image anomalously low resistivity zones associated with the presence of seepage pathways that were anthropogenic and/or natural in origin. Techniques including visual inspection (VI), multichannel analysis of surface waves (MASW), borehole control (BC), and aerial imagery (AI) were supplementally used to constrain the ERT data interpretations.

This research addressed six objectives. First, the ERT data interpretations were verified in terms of depth to the top of bedrock, fractures/voids, and moisture changes using the MASW, borehole control, and …

Mobility Analysis And Topology Synthesis Of Compliant Mechanism Using Compliance Number And Pseudo-Rigid-Body Model (Prbm), Pratheek Bagivalu Prasanna

Doctoral Dissertations

"Establishing and understanding the kinematic properties of a compliant mechanism has been a relatively recent endeavor and has proved to be a challenging task. A concept of compliance number was offered earlier; the development of terminologies was emphasized that aided in its determination. It also hypothesized that the compliance number (C) and stored strain energy, or mode shapes, are strongly correlated. This compliance number (C) concept is revisited, and a more lucid interpretation of its significance is provided. A fundamental understanding of the concept of deformation mode shapes in compliant mechanisms is formalized using two distinct categories: (i) segmental and …

Sensitivity Of The Two-Fluid Model To Constitutive Correlations For Large Diameter Pipes, Alexander Lee Swearingen

Doctoral Dissertations

"Multiphase flows are a significant factor in nuclear reactor operations. In order to understand this behavior in reactor systems, system analysis codes are used to simulate reactor conditions. Due to the nature of the nuclear industry, simulations predicting the void development in the core are required to be highly accurate. This work evaluated the sensitivity of the void fraction and interfacial area concentration predictions to changes in correlations used to calculate three parameters that are used to complete the interfacial drag calculation. The three parameters evaluated were drift-flux, void fraction covariance, and interfacial area concentration. The change in drift-flux correlation …

Mediating Language Fluency Development: An Action Research Study In A High-School Ap Chinese Second-Or-Foreign-Language Task-Based Language Teaching Classroom, Jing Liang

Doctoral Dissertations

Fluency development is critical in language learning; however, the teacher’s role as a mediator in a learner’s fluency development rarely has been explored in Task-Based Language Teaching (TBLT) classrooms. This study investigated how a teacher, as the human mediator who can be certain that stimuli in the learning environment will be available and benefit the learners, implemented mediation under the guidance of Mediated Learning Experience (MLE) theory in aiding learners’ speaking cognitive and utterance fluency development in one AP Chinese high-school TBLT classroom in the Bay Area. MLE theory, developed by psychologist Reuven Feuerstein, provided a mediation framework for this …

Genocide In East Turkestan: Exploring The Perspectives Of Uyghurs In The Diaspora And Their Resistance To Chinese State Violence, Lina Semyonovna Lenberg

Doctoral Dissertations

The Uyghurs of Xinjiang Uyghur Autonomous Region—or East Turkestan, as many Uyghurs call their Indigenous homeland in northwestern China, are a Muslim ethnic group whose culture and identity are being systematically destroyed by the Chinese state. Since 2016, Uyghurs have been imprisoned in China’s “re-education camps” on an enormous scale, numbering up to three million. Uyghurs have experienced discrimination and marginalization in China for many years, yet relatively little attention has been given to what has now become a set of gross human rights violations amounting to crimes against humanity and genocide. The purpose of this study was twofold. First, …

The Collegiate Black Space: Black College Students’ Use Of New Counter-Spaces For Support, Knowledge Production, And Organizing For Activism, Heather Streets

Doctoral Dissertations

Black collegians who attend historically white institutions continue to struggle with racism, microaggressions, feelings of alienation, minimal or improper advising, and an undue pressure to prove themselves (Bonner, 2010; Feagin & Sikes, 1995; Strayhorn, 2010). These barriers to success result in part due to a lack of support from the colleges and universities that they attend (Allen, 1992; Parker, Puig, Johnson & Anthony, Jr., 2016). With institutional benefits designed to benefit white students over students of color, Black students must find their own alternatives for collaboration and to provide support for their peers.

Many Black spaces can be defined as …

Efforts To Create A Trauma-Informed Classroom In Higher Education: Insights From Members Of A Community College Trauma-Informed Teaching Group, Danyelle Marshall

Doctoral Dissertations

BIPOC students attending a community college in the Bay Area bring traumas to school with them and then they relive their traumas in the classroom through professors’ pedagogy and the curriculum. This dissertation which was conducted during twin pandemics of COVID 19 and racism, researched a group of English professors that teach first generation community college students in their second year and above to understand what they know about trauma and their students and how they begin to conceive efforts to develop trauma-informed pedagogy. Data were collected using a focus group and individual interviews. The focus group created an environment …

Black Mothering In The Bay Area While Unseen And Unheard: Navigating Black Mothering In The Midst Of A Pandemic & Social Unrest, Kassie Michelle Phillips

Doctoral Dissertations

Black Mothering In The Bay Area While Unseen And Unheard: Navigating Black Mothering In The Midst Of A Pandemic & Social Unrest This narrative research study was conducted in Northern California while attending the School of Education at the University of San Francisco. Introducing a new theoretical framework called Black-Crit Mothering, this study examined the relationships of single and married Black Mothers living in the Bay Area and how Black Mothering has been directly impacted by the various pandemics that continue to take over the Black communities. These stories provided counter-narratives to the traditional views of our women in history …

"My Body Goes Numb A Lot Of The Time": Examining High School Student-Athlete Experiences Using Youth Participatory Action Research And Embodied Culturally Relevant Pedagogy, Gabriela Elizabeth Holmes

Doctoral Dissertations

For many students, the classroom represents a place of oppression, stress, and routine, in which their voices are silenced and they are expected to sit still, listen, take notes, and regurgitate the arbitrary information their teachers share (Freire, 1970/2000; Robinson & Aronica, 2015). Conversely, for many youth, sports are a source of joy, self-expression, creativity, and empowerment that naturally capture their interest and engagement (Duncan-Andrade, 2010; Spooner, 2002). Unfortunately, our education system fails to utilize the passion student-athletes demonstrate for sports to motivate them in the classroom. The purpose of this study is to explore the experiences of high school …

Towards Charism Identity: A Catholic Identity Case Study Through The Lens Of Laudato Si’, Kristofer Ross Koller

Doctoral Dissertations

This case study evaluates the current relevance of how Catholic identity is conceived as an evaluative tool in accreditation processes. Catholic identity, though a concept inconsistently defined among various international contexts, is nevertheless utilized reductively as criteria for K-12 Catholic school accreditation in the United States, primarily through the framework of the National Standards and Benchmarks for Effective Catholic Schools (NSBECS). Using the example of a secondary school with an explicit Catholic charism-based commitment to environmental sustainability, this dissertation collects qualitative data in an exploratory manner to evidence how schools that may seem insufficiently Catholic according to currently utilized frameworks …

Determining Thermal Properties Via Parameter Estimation Of A One-Dimensional, Analytical Model, Lauren B. Tomanek

Doctoral Dissertations

“In thermal applications, thermal conductivity is used to predict how well a material conducts heat. The accuracy of the magnitude of the thermal conductivity becomes increasingly essential to optimize part geometry. Thermal conductivity can vary significantly from the nominal value due to post-processing. The ASTM standards available to measure thermal conductivity are challenging to reproduce because of the insulated and prescribed temperature boundary conditions that are needed. The research introduces two new methods for estimating thermal conductivity that deliver the same accuracy as the existing ASTM standards and are easier to implement. The methods account for losses in the heating …

Modeling Strategy For Emi Filter And Flyback Transformer, Ruijie He

Doctoral Dissertations

“The switch-mode power supply is key to miniaturizing power adapters. However, the switching nature of the circuit introduces issues in conducted emissions. In a flyback converter, the transformer serves as the path for common mode current flowing from the primary side to the secondary side. Different winding technologies have been invented and implemented to reduce the capacitance between the primary side and the secondary side. But the repeatability of the winding is still poor due to the fluctuations of the winding machine. Thus, the resulting conducted emission has a fluctuation that can lead to failure in the compliance tests. EMI …

Characterization And Modeling Of Esd Events, Risk And Protection, Jianchi Zhou

Doctoral Dissertations

“The ESD (Electrostatic discharge) failures have been raising critical reliability problems in electronic devices design. However, not all the ESD scenarios have been specified by the IEC standard and the characterizations of the ESD risk for different scenarios are essential to evaluate the ESD robustness of the devices in the real word.

The insulation of plastic enclosures provides protection against ESD to the electronic system inside. However, seams between plastic parts are often unavoidable. Different plastic arrangements are constructed to investigate the spark length and current derivatives and to understand the ESD spark behavior for geometries having spark lengths longer …

Deep Learning-Based Surrogate Models For Post-Earthquake Damage Assessment, Xinzhe Yuan

Doctoral Dissertations

"Seismic damage assessment is a critical step to enhance community resilience in the wake of an earthquake. This study aims to develop deep learning-based surrogate models for widely used fragility curves to achieve more accurate and rapid assessment in practice. These surrogate models are based on artificial neural networks trained from the labelled ground motions whose resulting damage classes on targeted structures are determined by nonlinear time history analyses. The development of various surrogate models is progressed in four phases. In Phase I, the multilayer perceptron (MLP) is used to develop multivariate seismic classifiers with up to 50 hand-crafted intensity …

Replicating Nature: Functional And Morphological Biomimicry As Blueprints For Synthetic Macromolecular Structures, Erinn Kay Reville

Doctoral Dissertations

The aim of this dissertation is to provide insight into synthetic materials that replicate the function and structure of natural materials. First, a comprehensive overview of the challenges and recent advances in tailored synthetic molecular recognition through molecularly imprinted polymers (MIPs) will be presented. Chapter 2 of this work discusses the synthesis of azlactone-based homopolymers as functional polymers tuned for the detection of opioid molecules. Through the rapid and efficient ring-opening reaction of azlactone pendant chains with primary amines, customized functionalization of the homopolymers with receptor-like moieties was achieved post-polymerization. Chapter 3 explores the use of functionalized diblock copolymers as …

Application Of Signal Processing Techniques For Health Monitoring And Damage Detection Of Memorial Bridge, Forouzandeh Mazaherimeybodi

Doctoral Dissertations

Aging and deterioration and damage to infrastructure elements such as bridges, roads, and tunnels, are some of the biggest concerns to the uninterrupted operation of the US transportation network.Structural health monitoring (SHM) is one of the most powerful tools proposed by the civil engineering research community as an economical and objective method for civil infrastructure management and condition assessment. A typical SHM process consists of continuous or periodic estimations of structural parameters based on a sensor network, feature extraction, and statistical modeling for feature classification to detect any damage that occurred to the structure. Due to the evolution of building …