Digital Commons Network^™

Programming Problems On Time Scales: Theory And Computation, Rasheed Basheer Al-Salih

Doctoral Dissertations

"In this dissertation, novel formulations for several classes of programming problems are derived and proved using the time scales technique. The new formulations unify the discrete and continuous programming models and extend them to other cases "in between." Moreover, the new formulations yield the exact optimal solution for the programming problems on arbitrary isolated time scales, which solve an important open problem. Throughout this dissertation, six distinct classes of programming problems are presented as follows. First, the primal as well as the dual time scales linear programming models on arbitrary time scales are formulated. Second, separated linear programming primal and …

Dirac Surface States Of Magnetic Topological Insulators, Seng Huat Lee

Doctoral Dissertations

"Magnetic topological insulator (TI) has been theoretically proposed to be a platform for inducing magnetic monopole and exhibit fascinating quantum phenomena, whereas topological superconductor can host Majorana fermions, particles that are their own antiparticles, which can be manipulated for topological quantum computing. In this dissertation, we experimentally demonstrated that by intercalation of different transition metals in the van der Waals gaps of Bi₂Se₃ TI, magnetism and even superconductivity can be induced. In Fe_xBi₂Se₃, antiferromagnetism is induced with a transition temperature at ~ 100 K. Coexistence of the Dirac surface state with …

Depositional Systems, Sequence Architecture, And Controlling Factors Of An Eocene Stratigraphic Sequence At Minfeng Steep Margin Of Dongying Depression, Eastern China, Zhixin Li

Doctoral Dissertations

“This study is carried out in Minfeng area, the steep margin of Dongying half graben, eastern China, by integrating 3-D seismic, wireline log, and core data, and aims to interpret the depositional systems, reconstruct sequence stratigraphic architecture, and understand the controlling processes and factors at the steep margin of a rift basin. In the first part of this work, an Eocene stratigraphic sequence is divided into three systems tracts, corresponding to different stages of lake evolution, as early expansion (EEST), late expansion-early contraction (LEECST), and late contraction (LCST). EEST is the thickest and diagnostic by the best-developed marginal and basinal …

Designing High Performance Overall Water Splitting Electrocatalysts From Non-Precious Metal Selenides, Abdurazag T. Swesi

Doctoral Dissertations

“The energy production has been depending mostly on fossil fuel which will be depleted someday in the near future. Aspects such as the loss of energy resources and destruction of the environment have motivated researchers for pursuing transition away from fossil fuels to renewable solar-fuels. Therefore, in order to meet the continuous increasing demand for energy, the hydrogen, with the largest energy density stored in it, can then efficiently be used in fuel cells without concern of contaminants. Water splitting reaction to generate H₂ and O₂ is one promising method of converting solar energy into fuels. The major …

Development Of A Reference Database For Assessing Dietary Nitrate In Vegetables, Lauren Blekkenhorst, Richard Prince, Natalie Ward, Kevin Croft, Joshua Lewis, Amanda Devine, Sujata Shinde, Richard Woodman, Jonathan M. Hodgson, Catherine P. Bondonno

Research outputs 2014 to 2021

Scope: Nitrate from vegetables improves vascular health with short-term intake. Whether this translates into improved long-term health outcomes has yet to be investigated. To enable reliable analysis of nitrate intake from food records, there is a strong need for a comprehensive nitrate content of vegetables database.

Methods and results: A systematic literature search (1980–2016) was performed using Medline, Agricola and Commonwealth Agricultural Bureaux abstracts databases. The nitrate content of vegetables database contains 4237 records from 255 publications with data on 178 vegetables and 22 herbs and spices. The nitrate content of individual vegetables ranged from Chinese flat cabbage (median; range: …

Balanced Truncation Model Reduction Of Nonlinear Cable-Mass Pde System, Madhuka Hareena Lochana Weerasinghe

Doctoral Dissertations

We consider model order reduction of a cable-mass system modeled by a one dimensional wave equation with interior damping and dynamic boundary conditions. The system is driven by a time dependent forcing input to a linear mass-spring system at the left boundary of the cable. A mass-spring model at the right end of the cable includes a nonlinear stiffening force. The goal of the model reduction is to produce a low order model that produces an accurate approximation to the displacement and velocity of the mass in the nonlinear mass-spring system at the right boundary. We believe the nonlinear cable-mass …

Acquisition Of Active Multichannel Analysis Of Surface Waves (Masw) Data In Karst Terrain, Ghassan Salem Alsulaimani

Doctoral Dissertations

"This study was designed to verify the effects and data reproducibility when the length of receiver array, receiver spacing, source offset and array orientation parameters are changed for data acquired using multichannel analysis of surface waves (MASW), at intended target depth of 30ft (9m), and to compare the results with electrical resistivity tomography (ERT) data obtained for the same study site.

The MASW data acquired for 34 sites, along four profiles for each site using variable source offsets of 10ft (3m) and 30ft (9.1m), and variable receiver spacings of 2.5ft (0.76m) and 5.0ft (0.76m), concurrently. Out of the 272 profiles …

Local Holomorphic Extension Of Cauchy Riemann Functions, Brijitta Antony

Doctoral Dissertations

"The purpose of this dissertation is to give an analytic disc approach to the CR extension problem. Analytic discs give a very convenient tool for holomorphic extension of CR functions. The type function is introduced and showed how these type functions have direct application to important questions about CR extension. In this dissertation the CR extension theorem is proved for a rigid hypersurface M in C² given by y = (Re ω)^m(Im ω)ⁿ where m and n are non-negative integers. If the type function is identically zero at the origin, then there is no CR extension. …

Experimental And Computational Investigation Of Multi-Principal Element Alloys, Mohsen Beyramali Kivy

Doctoral Dissertations

"Multi-principal element (MPE) alloys, unlike traditional alloys, consist of five or more principal elements with near equi-atomic compositions creating a large new compositional space for exploring new alloy possibilities. However, designing MPE alloys with the desired phases, microstructures and properties is challenging task, and there is a demand for basic research for a better understanding of structure-processing-property relations in these alloys.

In this Ph.D. research, different computational models and experiments were integrated to study phase formations, and mechanical properties of different MPE alloys. Density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations were used to determine crystal structures, …

Numerical Investigation On Nonlocal Problems With The Fractional Laplacian, Siwei Duo

Doctoral Dissertations

"Nonlocal models have recently become a powerful tool for studying complex systems with long-range interactions or memory effects, which cannot be described properly by the traditional differential equations. So far, different nonlocal (or fractional differential) models have been proposed, among which models with the fractional Laplacian have been well applied. The fractional Laplacian (-Δ)^α/2 represents the infinitesimal generator of a symmetric α-stable Lévy process. It has been used to describe anomalous diffusion, turbulent flows, stochastic dynamics, finance, and many other phenomena. However, the nonlocality of the fractional Laplacian introduces considerable challenges in its mathematical modeling, numerical simulations, and mathematical …

Investigation Of Hydraulic Fracture Complexity And The Benefits Of Maximizing Or Minimizing Complexity In Unconventional Resources, Rashid Sheikh Kassim

Doctoral Dissertations

"This dissertation discusses two separate, yet inter-related studies. The first study was an extension of historical work comparing transversely fractured versus longitudinally fractured horizontal wells in multiphase flow environment. The second study investigated hydraulic fracture complexities and the benefits of maximizing or minimizing complexities in unconventional resources and tight reservoirs.

The main objective of this research was to investigate fracture complexity and its impact on well performance and economics. To achieve that objective, three different integrated completions and reservoir models were built. Two of the three models, a hybrid reservoir model and micro-seismic based SRV (stimulated reservoir volume) model, were …

Data Analytics Methods For Attack Detection And Localization In Wireless Networks, Yi Ling

Doctoral Dissertations

"Wireless ad hoc network operates without any fixed infrastructure and centralized administration. It is a group of wirelessly connected nodes having the capability to work as host and router. Due to its features of open communication medium, dynamic changing topology, and cooperative algorithm, security is the primary concern when designing wireless networks. Compared to the traditional wired network, a clean division of layers may be sacrificed for performance in wireless ad hoc networks. As a result, they are vulnerable to various types of attacks at different layers of the protocol stack. In this paper, I present real-time series data analysis …

Rock And Fluid Flow Characterization On Unconventional Reservoir Using Confocal-Laser-Microscopy And Micromodels, Songyuan Liu

Doctoral Dissertations

"Unconventional oil reservoirs have become significant sources of petroleum production and have even better potential in the future. Many unconventional oil systems consist of nanoscale pore throats, sub-micro-scale pores and micro-scale fractures that are significantly smaller than those from conventional reservoirs. To understand fluid flow behavior in unconventional reservoir, lab approaches were conducted using lab-on-chip method for the direct visualization of the water/oil flow in sub-micro-scale channels and the flow behavior with influence of surfactant and fractures.

In this work, tight sandstone thin slice was characterized using confocal-laser-microscope. Using designed micromodels, microscopic study of interface and residual oil distribution as …

Repair Of Metallic Components Using Hybrid Manufacturing, Renwei Liu

Doctoral Dissertations

"Many high-performance metal parts users extend the service of these damaged parts by employing repair technology. Hybrid manufacturing, which includes additive manufacturing (AM) and subtractive manufacturing, provides greater build capability, better accuracy, and surface finish for component repair. However, most repair processes still rely on manual operations, which are not satisfactory in terms of time, cost, reliability, and accuracy. This dissertation aims to improve the application of hybrid manufacturing for repairing metallic components by addressing the following three research topics. The first research topic is to investigate and develop an efficient best-fit and shape adaption algorithm for automating 3D models' …

Long-Period Fiber Grating Corrosion Sensors For Life-Cycle Monitoring And Assessment Of Reinforced Concrete Structures, Yizheng Chen

Doctoral Dissertations

"This study aims to: (1) explore, develop, calibrate and validate Fe-C coated, long period fiber grating (LPFG) sensors for short-term mass loss measurement of the Fe-C coating; (2) develop, calibrate, and validate steel tube-encapsulated, fiber optic probes and LPFG sensors for long-term mass loss detection of the steel tube; (3) correlate the corrosion process of packaging metal materials with that of steel bars in direct contact with the packaged probe or sensor except for a thin insulation tape; and (4) apply both types of corrosion sensors into reinforced concrete (RC) structures for reinforcing bar corrosion monitoring and structural condition assessment. …

Manufacturing Of Advanced Continuous Fiber Reinforced Composites For High Temperature Applications, James Robert Nicholas

Doctoral Dissertations

"New resin systems have enabled composites to be considered as attractive alternatives in structural applications that require material to be stronger, lighter and/or more resilient to environmental effects. The current work is on the development of processes to produce continuous fiber reinforced materials from two state of the art resin systems. Two processes were developed to produce continuous fiber reinforced ceramic materials from a preceramic polymer. The first was a vacuum forming process developed using the out-of-autoclave polymer composite manufacturing technique in conjunction with the polymer infiltration and pyrolysis process to produce ceramic composite material of zirconium diboride-silicon carbide reinforced …

Zero-Dimensional Spaces And Their Inverse Limits, Sahika Sahan

Doctoral Dissertations

"In this dissertation we investigate zero-dimensional compact metric spaces and their inverse limits. We construct an uncountable family of zero-dimensional compact metric spaces homeomorphic to their Cartesian squares. It is known that the inverse limit on [0,1] with an upper semi-continuous function with a connected graph has either one or infinitely many points. We show that this result cannot be generalized to the inverse limits on simple triods or simple closed curves. In addition to that, we introduce a class of zero-dimensional spaces that can be obtained as the inverse limits of arcs. We complete by answering a problem by …

Netnography: Range Of Practices, Misperceptions, And Missed Opportunities, Leesa N. Costello, Marie-Louise Mcdermott, Ruth M. Wallace

Research outputs 2014 to 2021

This is the first article to describe how broadening of the term netnography in qualitative research is leading to misperceptions and missed opportunities. The once accepted need for human presence in netnographic studies is giving way to nonparticipatory (passive) approaches, which claim to be naturalistic and bias-free. While this may be tenable in some environments, it also removes the opportunity for cocreation in online communities and social media spaces. By contrast, participatory (active) netnographers have an opportunity to conduct their research in a way that contributes value and a continuity of narrative to online spaces. This article examines the ways …

Drinking Water Disinfection By-Products Detection, Formation And The Precursors Removal Study, Runmiao Xue

Doctoral Dissertations

"Haloacetic acids (HAAs) and trihalomethanes (THMs) are two groups of commonly found disinfection by-products (DBPs). Iodinated THMs and HAAs were observed after disinfection of water containing high level of iodide and are proved to be more toxic than their corresponding chlorinated and brominated species. In the presented dissertation, a novel rapid and sensitive high performance ion chromatography-tandem mass spectrometry (HPIC-MS/MS) method has been developed for simultaneous analysis of all these HAAs, bromate, bromide, iodide, and iodate, seventeen compounds in total, without any tedious sample preparation. Besides an efficient analytical method for the detection of DBPs, seeking for a green disinfectant …

T-Closed Sets, Multivalued Inverse Limits, And Hereditarily Irreducible Maps, Hussam Abobaker

Doctoral Dissertations

"This dissertation consists of three subjects: T-closed sets, inverse limits with multivalued functions, and hereditarily irreducible maps.

For a subset A of a continuum X define T(A) = X \ {x ∈ X : there exists a subcontinuum K of X such that x ∈ int_xX(K) ⊂ K ⊂ X \ A}. This function was defined by F. Burton Jones and extensively investigated in the book [20] by Sergio Macias. A subset A of a continuum X is called T-closed set if T(A) = A. A characterization of T-closed set is given using generalized …

Imaging A Fly Ash Landfill Using Non-Invasive Technologies (Ert And Masw), Atiat Shaban Qasim Alsaaideh

Doctoral Dissertations

"Electrical resistivity tomography (ERT) data were acquired across a segment of an existing fly ash landfill in southwestern Missouri. The objective was to map potential karst features and identify probable groundwater seepage through and beneath the landfill.

Variations in the moisture content were mapped below and above the two liners (clay and synthetic) systems, the soil and bedrock. Seepage pathways were mapped through the fly ash and the underlying soil and rock. No visual evidence was found on any of the 3D ERT profiles of the presence of either pre-existing air-filled voids or pre-existing or newly infilled clay-filled voids. There …

Discrete Ordinates Ct Organ Dose Simulator (Doctors), Edward T. Norris

Doctoral Dissertations

"Computed tomography (CT) has become pervasive in medical diagnostics as improved imaging techniques and processing algorithms provide higher quality information to doctors. However, the exponentially increasing usage of CT has raised concerns regarding long term low-dose radiological risks.

Currently, the dose to patients is computed using Monte Carlo methods and experimental tests. In other areas of radiation transport, deterministic codes have been shown to be much faster than Monte Carlo codes.

Currently, no deterministic methodology exists to automatically generate a spatially distributed dose profile from a CT voxel phantom. This work proposes a new code, Discrete Ordinate CT Organ Dose …

Advanced Analytical Strategies To Determine Biomedical Parameters For Medical Diagnostics, Drug Delivery, And Therapy, Sisi Chen

Doctoral Dissertations

"Biomedical parameters are critical for diseases prognosis, diagnosis and therapy. Many research groups have dedicated their studies to develop analytical instrumentation and apply analytical methods to determine biomedical parameters that have the potential to help with disease control and increase public health. This dissertation focuses on three major aspects of analytical strategies development and applications: 1) detection of pH changes caused by nanotoxicity (induced by TiO₂ nanoparticles) using newly developed micro-pH sensor, 2) quantification of renal cell carcinoma (RCC) biomarkers by high-performance liquid chromatography - tandem mass spectrometry (HPLC-MS/MS), and 3) nuclear magnetic resonance (NMR) studies of porous wall …

Volumetric Error Compensation For 5-Axis Machine Tools, Jennifer Ruth Creamer

Doctoral Dissertations

"This work presents a geometric error compensation method for large 5-axis machine tools. The compensation method presented here uses tool tip measurements recorded throughout the axis space to construct a position-dependent geometric error model that can easily be used for error compensation. The measurements are taken using a laser tracker, permitting rapid error data gathering at most locations in the axis space. First two model types are compared for generating table-based error compensation and experimental results are presented. Table-based compensation is then extended to machine tool controller types with restrictions on the number or combination of compensation tables using an …

Quantitative Dependability And Interdependency Models For Large-Scale Cyber-Physical Systems, Koosha Marashi

Doctoral Dissertations

"Cyber-physical systems link cyber infrastructure with physical processes through an integrated network of physical components, sensors, actuators, and computers that are interconnected by communication links. Modern critical infrastructures such as smart grids, intelligent water distribution networks, and intelligent transportation systems are prominent examples of cyber-physical systems. Developed countries are entirely reliant on these critical infrastructures, hence the need for rigorous assessment of the trustworthiness of these systems. The objective of this research is quantitative modeling of dependability attributes -- including reliability and survivability -- of cyber-physical systems, with domain-specific case studies on smart grids and intelligent water distribution networks. To …

Survivability Modeling For Cyber-Physical Systems Subject To Data Corruption, Mark James Woodard

Doctoral Dissertations

"Cyber-physical critical infrastructures are created when traditional physical infrastructure is supplemented with advanced monitoring, control, computing, and communication capability. More intelligent decision support and improved efficacy, dependability, and security are expected. Quantitative models and evaluation methods are required for determining the extent to which a cyber-physical infrastructure improves on its physical predecessors. It is essential that these models reflect both cyber and physical aspects of operation and failure. In this dissertation, we propose quantitative models for dependability attributes, in particular, survivability, of cyber-physical systems. Any malfunction or security breach, whether cyber or physical, that causes the system operation to depart …

An Investigation Of Service Providers' Understanding, Perspectives And Implementations Of The Transdisciplinary Model In Early Intervention Settings For Children With Disabilities, Eimear Fitzmaurice,, Janet E. Richmond, Matthew Wittorf

Research outputs 2014 to 2021

Purpose

The transdisciplinary practice model is currently being promoted as best practice in early intervention therapy for children with disabilities. However, supporting literature is limited. Thus, the question is asked, “What are service providers' understanding and perception of the transdisciplinary model in early intervention settings for children with disabilities?”

Method

A systematic review was carried out using the Preferred Reporting Items for Systematic Reviews. An electronic search was conducted via six databases. Eight articles were selected

Results

Four studies predominantly focused on service providers’ perspectives of the model using semi-structured interviews or surveys. Many studies were of adequate to low …

An Exploration Of Cava Wineries: A Resource-Based Approach, Alonso Duarte

Research outputs 2014 to 2021

Purpose:

The purpose of this exploratory study is to identify the most important resources, and emerging issues among Spain’s Cava wineries, including opportunities and challenges, from predominantly winery operators, and through the lens of the resource-based view of the firm (RBVF).

Design/methodology/approach:

Unstructured, face-to-face, in-depth interviews were conducted with the representatives of five Cava firms, and with the manager of the local Institute of Cava in Sant Sadurnà d’Anoia, Spain. In addition, owners/managers of seven other Cava wineries provided responses and comments via email. Findings: The attributes pertaining to the RBVF, such as valuable, rare, imperfect imitable resources, and (non)substitutability …

Control Of Single- And Dual-Probe Atomic Force Microscopy, Muthukumaran Loganathan

Doctoral Dissertations

“Atomic force microscope (AFM) is one of the important and versatile tools available in the field of nanotechnology. It is a type of probe-based microscopy wherein an atomically sharp tip, mounted on the free end of a microcantilever, probes the surface of interest to generate 3D topographical images with nanoscale resolution. An integral part of the AFM is the feedback controller that regulates the probe deflection in the presence of surface height changes, enabling the control action to be used for generating topographical image of the sample. Besides sensing, the probe can also be used as a mechanical actuator to …

Data Analysis And Application Guidelines Of Particle Gel Treatments, Yue Qiu

Doctoral Dissertations

“Water production is a severe worldwide issue in mature oilfields, which results in shortening the economic life of oil and gas wells. Particle gel have been widely applied in mature oilfields to improve reservoir sweep efficiency and control water production. To date, more than 10,000 injection wells were successfully treated by particle gels. However, considerable uncertainty still exists regarding to where and how particle gel treatments can be best applied.

The main objective of this study is to provide application guidelines and prediction model for particle gel treatments through data analysis. In this study, four particle gel treatment datasets have …