Digital Commons Network^™

Decoupling Methods For The Time-Dependent Navier-Stokes-Darcy Interface Model, Changxin Qiu

Doctoral Dissertations

"In this research, several decoupling methods are developed and analyzed for approximating the solution of time-dependent Navier-Stokes-Darcy (NS-Darcy) interface problems. This research on decoupling methods is motivated to efficiently solve the complex Stokes-Darcy or NS-Darcy type models, which arise from many interesting real world problems involved with or even dominated by the coupled porous media flow and free flow. We first discuss a semi-implicit, multi-step non-iterative domain decomposition (NIDDM) to solve a coupled unsteady NS-Darcy system with Beavers-Joseph-Saffman-Jones (BJSJ) interface condition and obtain optimal error estimates. Second, a parallel NIDDM is developed to solve unsteady NS-Darcy model with Beavers-Joseph (BJ) …

Structure And Topology Of Transcriptional Regulatory Networks And Their Applications In Bio-Inspired Networking, Satyaki Roy

Doctoral Dissertations

"Biological networks carry out vital functions necessary for sustenance despite environmental adversities. Transcriptional Regulatory Network (TRN) is one such biological network that is formed due to the interaction between proteins, called Transcription Factors (TFs), and segments of DNA, called genes. TRNs are known to exhibit functional robustness in the face of perturbation or mutation: a property that is proven to be a result of its underlying network topology. In this thesis, we first propose a three-tier topological characterization of TRN to analyze the interplay between the significant graph-theoretic properties of TRNs such as scale-free out-degree distribution, low graph density, small …

Modeling Of Hiv, Sir And Sis Epidemics On Time Scales And Oscillation Theory, Gülşah Yeni

Doctoral Dissertations

"We study higher dimensional systems of first order dynamic equations on time scales together with their applications. In particular, we focus on epidemic models such as HIV (Human Immunodeficiency Virus), SIS (Susceptible-Infected-Susceptible) and SIR (Susceptible-Infected-Recovered).

First, we generalize the early studied continuous three dimensional linear model of drug therapy for HIV-1 decline on time scales in order to derive new discrete models that predict the total concentration of plasma virus as a function of time. We compare these models to explore the impact of the theory of time scales. After fitting the models to the data collected at a clinical …

Thermomechanical Analysis Of Rock Asperity In Fractures Of Enhanced Geothermal Systems, Chao Zeng

Doctoral Dissertations

"Enhanced Geothermal Systems (EGS) offer great potential for dramatically expanding the use of geothermal energy and become a promising supplement for fossil energy. The EGS is to extract heat by creating a subsurface system to which cold water can be added through injection wells. Injected water is heated by contact with rock and returns to the surface through production well. Fracture provides the primary conduit for fluid flow and heat transfer in natural rock. Fracture is propped by fracture roughness with varying heights which is called asperity. The stability of asperity determines fracture aperture and hence imposes substantial effect on …

A Computational Study Of Sleep And The Hemispheres Of The Brain, Tera Ashley Glaze

Doctoral Dissertations

"Sleep and sleep cycles have been studied for over a century, and scientists have worked on modeling sleep for nearly as long as computers have existed. Despite this extensive study, sleep still holds many mysteries. Larger and more extensive sleep-wake models have been developed, and the circadian drive has been depicted in numerous fashions, as well as incorporated into scores of studies. With the ever-growing knowledge of sleep comes the need to find more ways to examine, quantify, and define it in the context of the most complex part of the human anatomy -- the brain. Presented here is the …

The Behavior Of Suas Under Explosive Loading Conditions And Implications For Safe Operating Procedures, Ashok Em Sudhakar

Doctoral Dissertations

"Drones are increasingly being used for tasks previously unimagined and the beneficial uses are evolving. The United States Congress has envisioned the possible uses of drones for both combating and conveying explosive threats and other harmful and destructive activities. Congress' intent is reflected in new laws (2018) and policies (2019).

All civilian available Small Unmanned Aerial Systems sUASs (Drones), weighing less than 55 pounds, in the current market are not designed for operations in explosive environments. This first of a kind research focuses on further understanding of sUASs response to explosive loading and the public policy implications. This research measured …

Paleoenvironment And Paleoclimate Of Ne Pangea In Early Permian-Linking Chemo- And Cyclo-Stratigraphy, Bogda Mountains, Nw China, Xin Zhan

Doctoral Dissertations

"The overall objective of this study is to understand physical and chemical responses of Earth Systems to environmental and climatic perturbations of diverse magnitudes and time scales in Bogda Mountains, NE Pangea. Field investigations, petrographic observations, and geochemical analyses have been used to interpret paleoenvironment and paleoclimate in cm-m-scale high-order cycles (HCs: 0.1-100 kyrs), low-order cycles (LCs: 1-10 Myr), and critical events of late Paleozoic ice age (LPIA: 320-260 Myr ago). Four organo-facies are one-to-one correlated with the four lithofacies in the meter-scale HCs, suggesting litho- and organo-facies are genetically linked and fundamentally controlled by environmental changes associated with lake …

High Level Thermochemical And Spectroscopic Computations For Molecules Relevant To Combustion And The Atmosphere, Bradley K. Welch

Doctoral Dissertations

"Computational thermochemistry can be a complicated multistep process, but in recent years has become an equal partner with experiment. Many important molecules in combustion systems or in the atmosphere (such as short-lived radicals) are difficult to study experimentally. Predicting highly accurate thermochemistry is a key aspect in understanding these species. In this project, computational thermochemistry was developed into an automated streamlined procedure and then used to understand the methyl and ethyl peroxy families of radicals. This effort involved optimizing a standard workflow for computational thermochemistry. Computational thermochemistry generally requires numerous individual calculations whose cost and scalings vary widely. Conducting such …

Wavelength-Selective Metamaterial Absorber And Emitter, Zhigang Li

Doctoral Dissertations

"Electromagnetic absorbers and emitters have been attracting interest in lots of fields, which are significantly revitalized because of the novel properties brought by the development of the metamaterials, the artificially designed materials. Metamaterials broadens the approaches to design the electromagnetic absorbers and emitters, making it possible to obtain the perfect absorption or emission at the wavelengths covering a wide range. Metamaterial absorbers and emitters are promising for various applications, including solar thermal-photovoltaics and thermal-photovoltaics for energy harvesting, chemical and biomedical sensors, nanoscale imaging and color printing. This work focuses on three aspects (materials, structures and design methods) to improve the …

Seismic Attribute Assisted Depositional Facies Identification And Stratigraphic Correlation In The Central Gulf Coast Region Of Texas, Yani Lin

Doctoral Dissertations

"The sandstone deposits in the fluvial-dominated delta systems in the Lower Wilcox Group above the Cretaceous carbonate shelf edges of the Texas Gulf Coast Region are considered as high exploration potential reservoir bodies. However, the multi-phase regression and transgression during the late Paleocene to the early Eocene complicate the local depositional structure. The depositional facies is hard to be identified in details using the traditional seismic stratigraphic interpretation method. Seismic attributes are effective in detecting depositional facies, especially in mapping channels and investigating reservoir characteristics. In this study, we utilize seismic attributes to identify the principal depositional facies in the …

Deep Neural Network Learning-Based Classifier Design For Big-Data Analytics, Krishnan Raghavan

Doctoral Dissertations

"In this digital age, big-data sets are commonly found in the field of healthcare, manufacturing and others where sustainable analysis is necessary to create useful information. Big-data sets are often characterized by high-dimensionality and massive sample size. High dimensionality refers to the presence of unwanted dimensions in the data where challenges such as noise, spurious correlation and incidental endogeneity are observed. Massive sample size, on the other hand, introduces the problem of heterogeneity because complex and unstructured data types must analyzed. To mitigate the impact of these challenges while considering the application of classification, a two step analysis approach is …

Fault Imaging Enhancement In Taranaki Basin, New Zealand And Rock Physics And Inversion Based Reservoir Characterization In The Central Gulf Coast Region Of Texas, Tianze Zhang

Doctoral Dissertations

"Fault imaging technique and reservoir characterization based on rock physics analysis and pre-stack inversion has been widely used hydrocarbon exploration. For the fault imaging technique, the ant tracking has been widely used in fault interpretation. However, the reliability of the results is highly dependent on appropriately choosing a signal processing method and volume attributes. In our study area, which lies in the southern Taranaki Basin, we applied Graphic Equalizer as the processing tool and the Chaos attribute before running the ant tracking algorithm. Results show that the procedure provides a better result and can map both the major and minor …

New Reproducing Kernel Hilbert Spaces On Plane Regions, Their Properties, And Applications To Partial Differential Equations, Jabar S. Hassan

Doctoral Dissertations

"We introduce new reproducing kernel Hilbert spaces W₂^(m,n) (D) on unbounded plane regions D. We study linear non-homogeneous hyperbolic partial differential equation problems on D with solutions in various reproducing kernel Hilbert spaces. We establish existence and uniqueness results for such solutions under appropriate hypotheses on the driver. Stability of solutions with respect to the driver is analyzed and local uniform approximation results are obtained which depend on the density of nodes. The local uniform approximation results required a careful determination of the reproducing kernel Hilbert spaces on which the elementary …

Carbon-13 Kinetic Isotope Effects Of Catalytic Co2 Reduction By Polypyridyl Transition Metal Complexes, Taylor William Schneider

Doctoral Dissertations

Herein, we have used carbon-13 kinetic isotope effects (¹³C KIEs) to probe the catalytic CO₂ reduction mechanisms of two different polypyridyl transition metal complexes, Re(bpy)(CO)₃Cl (1), which will convert CO₂ to CO, and [Ru(tpy)(bpy)Cl]PF₆ (2) (bpy = 2,2’‑bipyridine; tpy = 2,2’:6’,2”-terpyridine), which will convert CO₂ to a mixture of CO and formic acid. We used several sets of reaction conditions to drive CO₂ reduction. These included sodium mercury (Na(Hg)) amalgam as a sacrificial reducing agent, photocatalytic conditions in which triethanolamine (TEOA) was a sacrificial electron donor, and …

Fine Scale Modeling To Estimate Human Exposures To Air Pollution, Fatema Parvez

Doctoral Dissertations

Traffic related air pollution is considered one of the major challenges for a large number of urban population. The rapid growth of the world’s motor-vehicle fleet due to population growth and economic improvement causes a significant negative impact on public health. As pollutants from roadway emission sources reach background concentration levels within a few hundred meters from the source, it is very challenging to implement a model that captures this behavior. Currently available air quality modeling approaches can compute the source specific pollutant fate on either a regional or a local scale but still lack effective ways to estimate the …

Optimal Selection Of Test Designs And Sensor Sets For Active Fault Diagnosis, Kyle Palmer

Doctoral Dissertations

Fault detection and isolation (FDI) is crucial to identifying problems that can occur in complex systems. Many industrial systems require the implementation of model-based FDI to reduce the risk of system failure and increase good performance while minimizing the use of additional hardware. Active FDI has become increasingly popular as it uses auxiliary tests to reduce the impact of uncertainty and improve fault diagnosis. A methodical approach is needed to consistently generate feasible test designs for the optimal detectability and isolability of faults in targeted systems. The focus of this dissertation is to design a general framework that improves the …

Strain Path Sensitive Polycrystal Plasticity Constitutive Models Within Finite Elements For Metal Forming Simulations, Milovan Zecevic

Doctoral Dissertations

An optimal sheet metal forming process shapes a metal part to the accurate geometry, while avoiding instabilities causing localization of deformation and fracture. Understanding the underlying mechanisms responsible for deformation localization and deviation of final part geometry from the desired geometry facilitates the search for the optimal sheet metal forming process. Accurate modeling of forming processes allows prediction of the formed part shape and can provide insight into the material behavior by interpretation of experimental measurements and prediction of variables not accessible to experimental characterization. In this work, a micromechanical material model is coupled with finite elements to create a …

A Combined Model Of Statistical Downscaling And Latent Process Multivariable Spatial Modeling Of Precipitation Extremes, Meng Zhao

Doctoral Dissertations

Future projections of extreme precipitation can help engineers and scientists with infrastructure design projects and risk assessment studies. Extreme events are usually represented as return levels which are equivalent to upper percentiles of an extreme value distribution, such as the Generalized Pareto distribution, which is used for exceedances above a certain threshold.

My dissertation focus is on uncertainty quantification related to estimation of future return levels for precipitation at the local (weather station) to regional level. Variance reduction is achieved through spatial modeling and optimally combining suites of climate model outputs. The main contribution is a unified statistical model that …

The 'Land Of Opportunity' Or The Land That Makes Us The Opportunity: An Examination Of Latinx For-Profit Choice Within The Central San Joaquin Valley, Joe A. Vasquez

Doctoral Dissertations

The San Joaquin Valley in Central California is known as an abundant agricultural epicenter with an extensive history of farming, migration, and political movements. Though this geography holds a rich representation of agricultural economy, it is also the site of major inequalities and underrepresentation, especially with regard to post-secondary education within its overrepresented Latinx population. Further amplifying the inequalities around post-secondary education and Latinx’s is the increasing occurrence of post-secondary enrollment into for-profit institutions by this population. Inequities associated with for-profit enrollment, such as high student loan debt and lack of career attainment, further stratify this geography classified as being …

Modeling And Control Of Partial Differential Equations (Pde) Described Systems, Tong Ma

Doctoral Dissertations

This proposed research is aimed to develop a novel modeling and control algorithm for the PDE described systems. When dealing with time-dependent PDE problems, the partial derivatives of a function over spatial variables are obtained by approximating the function values at interpolation nodes and their corresponding neighbors as a finite summation of polynomial series. A cluster of interpolation nodes guarantees the boundedness of the residual derivatives. Substituting these approximations in the PDE and discretizing the spatial domain of variables while keeping the time domain continuous yields a system of ODEs. By using an eigenvalue-based technique, a reduced-order model is derived, …

A Theory Of Timing Effects In A Self-Organizing Model Of Sentence Processing, Garrett Smith

Doctoral Dissertations

Many leading theories of human sentence processing assume that language compre- hension and production take place under the strict control of a symbolic grammar. For example, in sentence comprehension, reading or hearing a word triggers the application of a grammar rule that incorporates the word into the existing sentence structure so that the resulting structure is consistent with the all of the rules of the grammar. These theories have had wide success in explaining important timing effects, e.g., predicting speed-ups or slowdowns while reading a sentence. A number of phenomena have been identified, though, that challenge these grammar-controlled theories and …

Numerical Computation Of Traveling Wave And Standing Pulse Solutions To Fitzhugh-Nagumo Equations In 2d, Abdou Alzubaidi

Doctoral Dissertations

Algorithms are constructed to calculate standing pulse and traveling wave solu- tions for the FitzHugh-Nagumo equations in two dimensions. The algorithms are based on the application of a steepest descent method to some functionals. These algorithms are global in nature, in the sense that it does not require a good initial guess to guarantee convergence. Their numerical implementation involves construc- tion of asymptotic boundary conditions on truncated domains; asymptotic boundary conditions make the computation less expensive.

Our focus is on two special types of solutions for the FitzHugh-Nagumo equations: radially symmetric standing pulses in the whole space with Ω = …

Practicality And Application Of The Algebraic Side-Channel Attack, Chujiao Ma

Doctoral Dissertations

Algebraic Side-Channel Attack (ASCA) is a side-channel attack that models the cryptographic algorithm and side-channel leakage from a system as a set of equations, then solves for the secret key. Unlike pure side-channel attacks, ASCA has low data complexity and can succeed in unknown plaintext/ciphertext scenarios. However, past research on ASCA has been done on either 8-bit microcontroller data or simulated data. In this dissertation, we explore the application and feasibility of error tolerant ASCA on a field-programmable gate array (FPGA). FPGAs run faster and are more difficult for the encryption power trace to be isolated, so it presents more …

New Directions In Justification Logic, Joseph Lurie

Doctoral Dissertations

Justification logics are constructive analogues of modal logics. As such, they provide perspicuous models of those modalities that have inherently constructive character, such as intuitionistic mathematical provability or the knowledge operator of evidentialist epistemology. In this dissertation, I examine a variety of positions in epistemology, along with their associated ontological commitments, and develop various classical and non-classical justification logics that are suitable for use as models of these positions.

Lattice Dynamics Studies Of Negative Thermal Expansion Due To Two Low-Temperature Lattice Instabilities., Sahan Uddika Handunkanda

Doctoral Dissertations

Here I present a complete study of lattice dynamics of negative thermal expansion (NTE) material Scandium trifluoride (ScF₃) and discovery of NTE in mercurous iodide (Hg₂I₂). An inelastic x-ray scattering (IXS) study of ScF₃ reveals copious evidence of an incipient soft-mode instability indicating that the T=0 state of ScF₃ is very close to a structural quantum phase transition (SQPT). Is the anomalously strong and thermally persistent NTE behavior of ScF₃ a consequence of the SQPT? In order to address that, we have explored the coefficient of thermal expansion (CTE) and soft …

Understanding Of The Nucleation Induced Cooperative Behavior In Complex Macromolecular Systems, Hailin Fu

Doctoral Dissertations

Archival abstract submitted

Multidimensional Feature Engineering For Post-Translational Modification Prediction Problems, Norman Mapes Jr.

Doctoral Dissertations

Protein sequence data has been produced at an astounding speed. This creates an opportunity to characterize these proteins for the treatment of illness. A crucial characterization of proteins is their post translational modifications (PTM). There are 20 amino acids coded by DNA after coding (translation) nearly every protein is modified at an amino acid level. We focus on three specific PTMs. First is the bonding formed between two cysteine amino acids, thus introducing a loop to the straight chain of a protein. Second, we predict which cysteines can generally be modified (oxidized). Finally, we predict which lysine amino acids are …

Electromagnetic Wave-Matter Interactions In Complex Opto-Electronic Materials And Devices, Raj Kumar Vinnakota

Doctoral Dissertations

This dissertation explores the fundamentals of light-matter interaction towards applications in the field of Opto-electronic and plasmonic devices. In its core, this dissertation attempts and succeeds in the the modeling of light-matter interactions, which is of high importance for better understanding the rich physics underlying the dynamics of electromagnetic field interactions with charged particles. Here, we have developed a self-consistent multi-physics model of electromagnetism, semiconductor physics and thermal effects which can be readily applied to the field of plasmotronics and Selective Laser Melting (SLM). Plasmotronics; a sub-field of photonics has experienced a renaissance in recent years by providing a large …

Effective Magnetic And Electric Response Of Composite Materials, Mona Hassan Alsaleh

Doctoral Dissertations

Metamaterials (MMs) are nanocomposite materials consisting of metal-dielectric resonators much smaller in size than the wavelength of the incident light. Common examples of metamaterials are based on split ring resonators (SRRs), parallel wires or strips and fishnet structures. These types of materials are designed and fabricated in order to provide unique optical responses to the incident electromagnetic radiation that are not available in naturally existing materials. The MMs can exhibit unusual properties such as strong magnetism at terahertz (THz) and optical frequencies. Additionally, negative index materials (NIMs) can provide negative index of refraction which can be used in many applications …

Investigating High Energy Mixing In Cement-Based Materials, Aileen Vandenberg

Doctoral Dissertations

One of the current challenges to nano-engineering cementitious composite materials is obtaining properly dispersed nano-sized particles in the cementitious composite matrix. Properly dispersed nanoparticles can lead to an improved particle packing density, a key parameter to improving the mechanical, chemical, and sustainable properties of the cementitious composite. Broadening the particle size distributions of cementitious materials, such as ultra-high performance concrete (UHPC), to include additional nano-sized particles is a challenge that requires a better understanding of how they self-assemble in the cementitious matrix. Thus, the purpose of this research is to investigate the role mixing plays in multi-scale, multi-phase self-assembling cement-based …