Physical Sciences and Mathematics Commons^™

Empirical Bayes Estimates For The Reproduction Number Of Epidemics, Elijah Lee Hight

Theses and Dissertations

Epidemic outbreaks can be modelled as a branching process in which the total progeny or outbreak size, follows a Borel-Tanner (BT) distribution. Following a procedure described by Liang (2009), we construct empirical Bayes estimates for when the initial number of infected is a specified value r. Following the construction, we then simulate data and perform a numerical study, assuming BT distribution for the parameter θ, the reproduction number, with an initial outbreak size of three. Simulation results indicate that the empirical estimator suffers from “jumpiness.” We then proceed to monotonize the empirical estimate via a method outlined by Houwelingen (1979). …

Investigation Of Techniques And Their Application For The Cryopreservation Of Algal Species, Jazmine Leija

Theses and Dissertations

An alternative source for petroleum-based crude oils are algae derived biofuels. Fossil fuels are harmful for the environment, expensive and becoming scarce. There has been an increase in research on environmentally sustainable energy, using lipids derived from microalgae, which can be converted into biofuel. The use of microalgae as a source for biofuels has a lot of benefits including decreasing greenhouse gas emissions, rapid fuel production, absorption of carbon dioxide, and production of a renewable source of energy.

Algae cryopreservation aids in the maintenance of the best algae strains selected for producing lipids for biofuels. Cryopreservation will help minimize genetic …

Particle Trajectories In Shallow Water Models, Diana Torres

Theses and Dissertations

In this paper we will study particle trajectories under shallow water waves. We will examine equations such as the Korteweg-de Vries and systems dealing with Boussinesq and Euler's Equations to find relationships between particles irrotational velocities. Their solutions and behavior when modeling interacting surface waves will be explored. An attempt to find approximate solutions with different parameters, such as small amplitude and long-crested waves, that will lead to new information and study will be discussed.

Applications Of Vanadium Phthalocyanine In Catalytic, Acid-Based Medium To Couple Sugar Molecules, Juan Ricardo Luna

Theses and Dissertations

The vanadium-substituted tetraazatetrabenzoporphyrin, vanadium phthalocyanine, was synthesized via reflux and characterized using FITR and XRD analysis. Subsequent to synthesis, the vanadium phthalocyanine was studied as a catalyst in redox reactions to convert fructose to different molecules, the products were predominately levulinic methyl ester and heptadionic acid. The ability to convert fructose to other compounds, such as alkyl levulinic derivative, is an important process to help eliminate reliance on traditional chemical feed stocks and promote alternative fuels. Levulinic acid has been commonly used as a starting material in the synthesis of biofuels and a precursor for pharmaceuticals, plasticizers, THF derivatives, γ-valerolatone. …

Backcountry Campsite Environmental Changes And Effective Monitoring Practices: A Case Study In Kenai Fjords National Park, Shannon T. Wesstrom, Christopher Monz

Environment and Society Student Research

This report examines existing backcountry campsites’ resource conditions over a five-year period in Kenai Fjords National Park (KEFJ), Alaska. Using campsite ecological monitoring techniques, 101 campsites were assessed for area size, vegetation cover loss, condition class assessments, as well as other indicator variable measurements. This research utilized parametric, non-parametric, robust linear regression, and principal component analysis statistical approaches to inform park managers of:

• Spatial and temporal patterns in changing campsite ecological variable conditions.
• Predicted annual variability of each ecological variable by campsite, beach, and bay.
• Opportunities for possible improvements in the efficiency of the current monitoring protocol by identifying:
  • An …

Wavelength And Power Dependence On Multilevel Behavior Of Phase Change Materials, Gary A. Sevison, Joshua A. Burrow, Haiyun Guo, Andrew M. Sarangan, Joshua R. Hendrickson, Imad Agha

Electro-Optics and Photonics Faculty Publications

We experimentally probe the multilevel response of GeTe, Ge2Sb2Te5 (GST), and 4% tungsten-doped GST (W-GST) phase change materials (PCMs) using two wavelengths of light: 1550 nm, which is useful for telecom-applications, and near-infrared 780 nm, which is a standard wavelength for many experiments in atomic and molecular physics. We find that the materials behave differently with the excitation at the different wavelengths and identify useful applications for each material and wavelength. We discuss thickness variation in the thin films used as well and comment on the interaction of the interface between the material and the substrate with regard to the …

Voltage-Controlled Magnetization In Chromia-Based Magnetic Heterostructures, William Echtenkamp

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

Spintronics promises a new generation of low-power, high-speed, non-volatile memory and logic devices. Heterostructures based on magnetoelectric chromia enable the direct manipulation of magnetization by applied electric fields and emerged as a promising building block for spintronic devices. In this dissertation, several interesting emergent magnetic properties arising in these device-enabling building blocks are examined. In some cases, exchange coupling at the interface between the magnetoelectric antiferromagnet and an adjacent ferromagnet stabilizes the interfacial antiferromagnetic domain state against the electrically induced rotation of the bulk spin structure. Upon magnetically cycling the ferromagnet, the magnetoelectric antiferromagnet relaxes towards a commensurate spin structure …

Multi-Modal Data Fusion, Image Segmentation, And Object Identification Using Unsupervised Machine Learning: Conception, Validation, Applications, And A Basis For Multi-Modal Object Detection And Tracking, Nicholas Lahaye

Computational and Data Sciences (PhD) Dissertations

Remote sensing and instrumentation is constantly improving and increasing in capability. Included within this, is the increase in amount of different instrument types, with various combinations of spatial and spectral resolutions, pointing angles, and various other instrument-specific qualities. While the increase in instruments, and therefore datasets, is a boon for those aiming to study the complexities of the various Earth systems, it can also present a large number of new challenges. With this information in mind, our group has set our aims on combining datasets with different spatial and spectral resolutions in an effective and as-general-as-possible way, with as little …

Exploring Behaviors Of Software Developers And Their Code Through Computational And Statistical Methods, Elia Eiroa Lledo

Computational and Data Sciences (PhD) Dissertations

As Artificial Intelligence (AI) increasingly penetrates all aspects of society, many obstacles emerge. This thesis identifies and discusses the issues facing Computer Vision and significant deficiencies in the Software Development Life-cycle that need to be resolved to facilitate the evolution toward true artificial intelligence. We explicitly review the concepts behind Convolutional Neural Network (CNN) models, the benchmark for computer vision. Chapter 2 highlights the mechanisms that have popularized CNNs while also specifying significant gaps that could garner the model inadequate for future use in safety-critical systems. We put forward two main limitations. Namely, CNNs do not use lack of information …

Results On Nonorientable Surfaces For Knots And 2-Knots, Vincent Longo

Department of Mathematics: Dissertations, Theses, and Student Research

A classical knot is a smooth embedding of the circle into the 3-sphere. We can also consider embeddings of arbitrary surfaces (possibly nonorientable) into a 4-manifold, called knotted surfaces. In this thesis, we give an introduction to some of the basics of the studies of classical knots and knotted surfaces, then present some results about nonorientable surfaces bounded by classical knots and embeddings of nonorientable knotted surfaces. First, we generalize a result of Satoh about connected sums of projective planes and twist spun knots. Specifically, we will show that for any odd natural n, the connected sum of the n-twist …

The Activity Of Abstraction In Physical Chemistry Problem Solving And Instruction, Jessica M. Karch

Graduate Doctoral Dissertations

Productive problem solving, concept construction, and sense making occur through the core process of abstraction. Although the capacity for domain-general abstraction is developed at a young age, the role of abstraction in increasingly complex and disciplinary environments, such as those encountered in undergraduate STEM education, is not well understood. Undergraduate physical chemistry relies particularly heavily on abstraction because it uses many overlapping and imperfect mathematical models to represent and interpret phenomena occurring on multiple scales. To reconcile these models, extract meaning from them, and recognize when to apply them in problem solving requires processes of abstraction. This dissertation aims to …

Cfr-Mix: Solving Imperfect Information Extensive-Form Games With Combinatorial Action Space, Shuxin Li, Youzhi Zhang, Xinrun Wang, Wanqi Xue, Bo An

Research Collection School Of Computing and Information Systems

In many real-world scenarios, a team of agents must coordinate with each other to compete against an opponent. The challenge of solving this type of game is that the team's joint action space grows exponentially with the number of agents, which results in the inefficiency of the existing algorithms, e.g., Counterfactual Regret Minimization (CFR). To address this problem, we propose a new framework of CFR: CFR-MIX. Firstly, we propose a new strategy representation that represents a joint action strategy using individual strategies of all agents and a consistency relationship to maintain the cooperation between agents. To compute the equilibrium with …

Impact Of Calcium Carbonate Reactant Size And Mineralogy On Dolomite Stoichiometry, Katharine G. Rose

Masters Theses

Dolomite is a common, diagenetic, Mg-Ca carbonate mineral. Dolomitization occurs by a dissolution-precipitation reaction between a CaCO₃ precursor (calcite or aragonite) and Mg bearing fluids. The amount of Mg in dolomite, referred to as dolomite stoichiometry (mol% MgCO₃), varies in natural dolomites (38-50 mol% MgCO₃). Laboratory experiments have shown that dolomite stoichiometry is dependent on physiochemical factors of the diagenetic fluids (i.e., temperature, salinity, and Mg/Ca). The impact of the CaCO₃ precursor on stoichiometry, however, has not been studied directly. This study tests how the CaCO₃ precursor size (sieve size) and mineralogy (calcite …

Per- And Polyfluorinated Alkyl Substances (Pfas) Cycling Within Michigan: Connections Between Contaminated Sites, Landfills, And Wastewater Treatment Plants, Ross W. Helmer

Masters Theses

The disposal and treatment of Per- and Polyfluorinated Alkyl Substances (PFAS) contaminated solid and liquid wastes, and associated cycling within the natural and engineered environment is a complex topic. PFAS data on contaminated sites, landfill leachates, the influent, effluent, and biosolids from wastewater treatment plants (WWTPs) within Michigan were compiled from publicly available and private sources. Most of the datasets are based on a 28-analyte suite generated using a modified form of the US EPA 537 analytical method, with a subset of data from the 18-analyte ASTM D7979-19 method. Approximately 70% of the 171 contaminated sites in Michigan have maximum …

Toward Explainable Deep Anomaly Detection, Guansong Pang, Charu Aggarwal

Research Collection School Of Computing and Information Systems

Anomaly explanation, also known as anomaly localization, is as important as, if not more than, anomaly detection in many realworld applications. However, it is challenging to build explainable detection models due to the lack of anomaly-supervisory information and the unbounded nature of anomaly; most existing studies exclusively focus on the detection task only, including the recently emerging deep learning-based anomaly detection that leverages neural networks to learn expressive low-dimensional representations or anomaly scores for the detection task. Deep learning models, including deep anomaly detection models, are often constructed as black boxes, which have been criticized for the lack of explainability …

Unlinkable And Revocable Secret Handshake, Yangguang Tian, Yingliu Li, Guomin Yang, Guomin Yang

Research Collection School Of Computing and Information Systems

In this paper, we introduce a new construction for unlinkable secret handshake that allows a group of users to perform handshakes anonymously. We define formal security models for the proposed construction and prove that it can achieve session key security, anonymity and affiliation hiding. In particular, the proposed construction ensures that (i) anonymity against protocol participants (including group authority) is achieved since a hierarchical identity-based signature is used in generating group user's pseudonym-credential pairs and (ii) revocation is achieved using a secret sharing-based revocation mechanism.

Biasrv: Uncovering Biased Sentiment Predictions At Runtime, Zhou Yang, Muhammad Hilmi Asyrofi, David Lo

Research Collection School Of Computing and Information Systems

Sentiment analysis (SA) systems, though widely applied in many domains, have been demonstrated to produce biased results. Some research works have been done in automatically generating test cases to reveal unfairness in SA systems, but the community still lacks tools that can monitor and uncover biased predictions at runtime. This paper fills this gap by proposing BiasRV, the first tool to raise an alarm when a deployed SA system makes a biased prediction on a given input text. To implement this feature, BiasRV dynamically extracts a template from an input text and from the template generates gender-discriminatory mutants (semanticallyequivalent texts …

Modeling Transitions Of Focal Entities For Conversational Knowledge Base Question Answering, Yunshi Lan, Jing Jiang

Research Collection School Of Computing and Information Systems

Conversational KBQA is about answering a sequence of questions related to a KB. Follow-up questions in conversational KBQA often have missing information referring to entities from the conversation history. In this paper, we propose to model these implied entities, which we refer to as the focal entities of the conversation. We propose a novel graph-based model to capture the transitions of focal entities and apply a graph neural network to derive a probability distribution of focal entities for each question, which is then combined with a standard KBQA module to perform answer ranking. Our experiments on two datasets demonstrate the …

Deconvolving Kernel Regression Function Estimation Based On Right Censored Data, Erol Ozkan

Mathematics Dissertations

In this study, we propose a new regression function estimator when the observa- tion is contaminated in the convolution model with error in independent variable. We want to examine the e ect of the error variables when the data is right censored. The tail behavior of the characteristic function of the error distribution is used to describe the optimum local and global rates of convergence of these kernel estimators. We show that depending on the error is either ordinary smooth or super smooth, there are two sorts of convergence rates in adjusted mean square error for the regression function estimator. …

On Different Computational Aspects For Box-Cox Transformation Cure Rate Model, Pei Wang

Mathematics Dissertations

Cure rate modeling is an emerging area of research not only in biomedical science but also in other disciplines such as sociology, criminal justice, economics and engineering reliability. In the first part of this thesis, use of the wider class of generalized gamma distributions is proposed as the distribution of the lifetime for a particular transformation cure rate model, known as the Box-Cox transformation cure rate model. The maximum likelihood estimation of the Box-Cox transformation cure model parameters is studied through the calculated bias, mean square error and coverage probabilities of the asymptotic confidence intervals. The flexibilities of both generalized …

On A Cubic Nonlinear Equation Model Arising In Shallow Water Theory, Osama Salameh Alkhazaleh

Mathematics Dissertations

The shallow water waves theory produces numerous integrable equations with cubic non- linearity as asymptotic models. We began our work by formally deriving a model equation for the free surface elevation η with higher-order terms from shallow water in the Euler equation for an incompressible fluid with the simplest bottom and surface conditions. This model equation is truncated at the order O(ε3,εμ) and contains higher-order terms, which are useful for deriving a class of unidirectional wave equations including cubic nonlinear terms. Next, we derived an equation with cubic nonlinearity as the asymptotic method from the classical shallow-water theory by employing …

Liutex-Based Vortex Identification Methods And Their Application In Dns Study Of Flat Plate Boundary Layer Transition, Pushpa Shrestha

Mathematics Dissertations

Vortices are intuitively known as the rotational motion of fluid particles, however, unambiguous and universally accepted methods of vortex definition and identification are not available to date in the literature. First-generation vortex identification methods, also known as vorticity-based vortex criterion, were first proposed by Helmholtz. But these methods have their own problems. These methods have a shear contamination problem, and these methods did not accurately show the direction of fluid rotation. So, to overcome these problems, eigenvalues based second-generation vortex identification methods like Q, Δ, λ_(2 ), λ_(ci ), and Ω have been proposed. Most of these second-generation methods are …

Mathematical Approach Of Liutex Core Line And Liutex Core Tube For Vortex Structure Visualization, Dalal Khalid B Almutairi

Mathematics Dissertations

During the past decades, many vortex identification methods have been published to present a clear definition and identification of the vortex. However, all these methods are failed to offer a unique identification method, and they also cannot answer the six essential issues for vortex identification methods, which are: 1) absolute strength, 2) relative strength, 3) rotational axis, 4) vortex core center location, 5) vortex core size, and 6) vortex boundary. In this work, two vortex identification methods, which are never affected by the threshold, will be proposed. Moreover, this study will address two critical questions: 1) Where is the rotational …

The Natural Middle Of A Complete Resolution, Rebekah J. Aduddell

Mathematics Dissertations

It is widely known that minimal free resolutions of a module over a complete intersection ring have nice patterns that arise in their Betti sequences. In the late 1990's Avramov, Gasharov and Peeva defined a new class of R-modules that would exhibit similar patterns in their free resolutions. In doing so, they additionally defined the notion of critical degree for an R-module, which serves as a “flag” for when such patterns arise in the module’s Betti sequence. The main purpose of this thesis is to present an extension of critical degree to the category of totally acyclic complexes, Ktac(R), where …

Compressive Deconvolution Of Mri Imaging Via ℓ1 − ℓ2 Regularization, Talon Johnson

Mathematics Dissertations

The evolution of technology has drastically impacted the imaging field, particularly magnetic resonance imaging (MRI). Compared to other imaging technologies, MRI offers multiple contrasting mechanisms to distinguish tissues and fat, is radiation-free, and provides anatomical and molecular information about the tissue in question. However, data acquisition times to produce those images require a patient to lie still for a relatively long time. Consequently, it may lead to the voluntary or involuntary movement of the patient due to discomfort. Combined with the underlying issue of inherent noise, MRI is often blurry and contains artifacts. Mathematically, one can describe this behavior as …

Ichthyofaunal Utilization Of A Man-Made Salt Marsh Creak In Mission Bay, California, 25 Years After Creation, Maria Angst

McNair Summer Research Program

Southern California’s wetlands are drastically declining due to human activities. Increasingly, marsh restoration and creation are being used to mitigate such losses. This study used minnow traps to resample the ichthyofauna of a created marsh (Crown Point Mitigation Site; CPMS) and an adjacent natural marsh (Kendall Frost) in Mission Bay, California, 26 years following the marsh creation. These data were compared to data collected from 1995-1998, immediately after marsh creation. Fishes trapped included Fundulus parvipinnis, Gillichthys mirabilis, Ctenogobius sagittula, Atherinops affinis, and Mugil cephalus. Species richness and dominance measures were higher in the natural relative to the created marsh. The …

Theoretical And Observational Analysis Of Ice Particles For Improvement Of Ice Microphysical Models, Vanessa Przybylo

Legacy Theses & Dissertations (2009 - 2024)

Frozen hydrometeors can grow to acquire a multitude of shapes and sizes, which influence the distribution of mass within cloud systems. Aggregates have a variety of formations based on initial ice particle size, shape, falling orientation, and the number of particles that collect. This work employs the theoretical Ice Particle and Aggregate Simulator (IPAS) as a statistical tool to repetitively collect ice crystals to derive bulk aggregate characteristics.

Teaching Students How To Code Qualitative Data: An Experiential Activity Sequence For Training Novice Educational Researchers, Jennifer E. Lineback

University of South Florida (USF) M3 Publishing

Coursework on qualitative research methods is common in many collegiate departments, including psychology, nursing, sociology, and education. Instructors for these courses must identify meaningful activities to support their students’ learning of the domain. This paper presents the components of an experiential activity sequence centered on coding and coding scheme development. Each of the three component activities of this sequence is elaborated, as are the students’ experiences during their participation in the activities. Additionally, the issues concerning coding and coding scheme development that typically emerge from students’ participation in these activities are discussed. Results from implementations of both in-person (face-to-face) and …

A Novel Numerical Method For Solving Fractional Diffusion-Wave And Nonlinear Fredholm And Volterra Integral Equations With Zero Absolute Error, Mutaz Mohammad, Alexandre Trounev, Mohammed Alshbool

All Works

In this work, a new numerical method for the fractional diffusion-wave equation and nonlinear Fredholm and Volterra integro-differential equations is proposed. The method is based on Euler wavelet approximation and matrix inversion of an M × M collocation points. The proposed equations are presented based on Caputo fractional derivative where we reduce the resulting system to a system of algebraic equations by implementing the Gaussian quadrature discretization. The reduced system is generated via the truncated Euler wavelet expansion. Several examples with known exact solutions have been solved with zero absolute error. This method is also applied to the Fredholm and …

Explicit Inverse Of Near Toeplitz Pentadiagonal Matrices Related To Higher Order Difference Operators, Bakytzhan Kurmanbek, Yogi Erlangga, Yerlan Amanbek

All Works

This paper analyzes the inverse of near Toeplitz pentadiagonal matrices, arising from a finite-difference approximation to the fourth-order nonlinear beam equation. Explicit non-recursive inverse matrix formulas and bounds of norms of the inverse matrix are derived for the clamped–free and clamped–clamped boundary conditions. The bound of norms is then used to construct a convergence bound for the fixed-point iteration of the form u=f(u) for solving the nonlinear equation. Numerical computations presented in this paper confirm the theoretical results.