Digital Commons Network^™

The Relationship Between Experienced Workplace Incivility And Pre- Quitting Behaviors: A Model Of Mediated Moderation, Matt Lovett

Doctoral Dissertations

Workplace incivility is a non-overt and subtle form of workplace mistreatment. Though these low-intensity behaviors are often ambiguous, they display a lack of regard for people and are intended to harm. Yet the workplace incivility literature lacks in many areas, including its inclusion into more novel models. Therefore, this dissertation addressed several gaps in the workplace incivility literature, including distinguishing and measuring the impact of different sources of incivility, the social power of the instigators, and the distal outcome of pre-quitting behaviors. The researcher tested a unique theoretical model that included supervisor-and customer-instigated incivility, and illegitimate task assignment, as predictors …

Parallel Computing Framework And Gpu Performance Modeling, Wenjing Xu

Doctoral Dissertations

During the past decades, High-Performance Computing (HPC) has been widely used in various industries. In particular, the exponential growth of GPU (graphics processing unit) is a key technology that has helped promoting the development of artificial intelligence in real-world use cases. When we use GPU to accelerate parallel applications, its programmability, resource management, and scheduling are non-trivial jobs to obtain optimized performance. Therefore, how to effectively exploit GPU resources and improve program performance has been a hot research topic recently.

Benchmark does not always provide a good picture of the performance and details of the parallel applications. The various kinds …

Security-Related Technostress Trifecta On Employees’ Security Counterproductive Behaviors, Bao Duong

Doctoral Dissertations

Information security technology has become more important in preventing and protecting organizational digital assets, and employees are often considered the last line of defense. However, employees at all levels have to face and deal with the complexity, overload, and uncertainty of information security technology in their jobs every day. Although information security technology could benefit the organization and individual employees as it is critical to building and strengthening protection mechanisms for organizational digital assets and employees’ data, it could also negatively affect employees’ emotions and work accomplishments.

This study examines the two effects of psychological techno-stress responses (security-techno distress and …

Ecological Restoration Of Lead/Zinc/Copper Mine Tailings: Phytomanagement And Amendment Strategies To Enhance Substrate Functionality And Biomass Production, Mariam K. Al-Lami

Doctoral Dissertations

“The extreme physiochemical characteristics of mine tailings inhibit microbial processes and natural plant growth. Consequently, vast and numerous tailings sites remain barren for decades and highly susceptible to wind and water erosion. Phytostabilization is a cost-effective and ecologically productive remediation approach; however, tailings revegetation is generally challenging and must often be assisted with appropriate soil amendments. Amendments applied individually in greenhouse studies discussed herein revealed notable improvement in bioenergy crops growth only with biosolids treatments. Recalcitrant carbon amendments (biochar and humus) showed notable impact only on tailings physichochemical and hydraulic properties. Nevertheless, biosolids may not support sustained vegetation due to …

Effects Of Vacancies And Electron Temperature On The Electron Phonon Coupling In Cubic Silicon Carbide And Their Connection To The Inelastic Thermal Spike, Salah Al-Smairat

Doctoral Dissertations

“The electron-phonon interaction is an important interaction in many solids as it influences transport phenomena and related quantities such as the electrical and thermal conductivities, especially in nuclear and space applications. The importance of the electron-phonon interaction in primary damage production in 3C-SiC is the subject of this research.

The electron-phonon coupling factor was calculated using a hybrid Density Functional Perturbation Theory - Classical Electron Gas model. The coupling factor was calculated as a function of electron temperature in pristine and defective 3C-SiC, and relaxed defective cells. The electron-phonon coupling is found to depend strongly on the electronic temperature and …

The Utilization And Loss Of Available Energy In Aerospace Systems, Mohammad Abbas

Doctoral Dissertations

“Theoretical principles and analytical methodology for the control volume-based energy availability methodology for aerospace vehicles are developed; applications are made to jet-propelled and rocket-propelled vehicles as well as to stand-alone engine systems. Energy availability utilization characteristics of a modeled turbojet engine are studied across a wide range of operating conditions of throttle setting, flight altitude, and flight Mach number. The method is also extended to consider jet-powered vehicles. Fundamental principles regarding entropy generation and energy availability are developed, including directly linking entropy generation and maximum range and endurance of a powered aircraft. Theory and application of the energy utilization methodology …

Representation Learning On Heterogeneous Spatiotemporal Networks, Dakshak Keerthi Chandra

Doctoral Dissertations

“The problem of learning latent representations of heterogeneous networks with spatial and temporal attributes has been gaining traction in recent years, given its myriad of real-world applications. Most systems with applications in the field of transportation, urban economics, medical information, online e-commerce, etc., handle big data that can be structured into Spatiotemporal Heterogeneous Networks (SHNs), thereby making efficient analysis of these networks extremely vital. In recent years, representation learning models have proven to be quite efficient in capturing effective lower-dimensional representations of data. But, capturing efficient representations of SHNs continues to pose a challenge for the following reasons: (i) Spatiotemporal …

Corrosion Protection Mechanisms Of Trivalent Chromium Based Passivations On Γ-Znni Coated Al6061-T6 Alloy, Kevin Foster

Doctoral Dissertations

“The role of cobalt in trivalent chromium passivations (TCPs) to improve corrosion resistance of γ-ZnNi coated steel and aluminum is based on its effect on hexavalent chromium content in the passive layer. Investigations of both a cobalt-containing and cobalt-free TCP on SAE 1008 steel indicated that both passivations protect well for up to 1000 hours in neutral salt spray exposure (SSE). A repetition on Al 6061-T6 alloy indicated that TCP performed much better than cobalt-free TCP implicating the underlying substrate. Optical and electron micrographs indicated physical changes such as crack thickness, crack density, passivation porosity, and passivation thickness existed between …

Theoretical And Experimental Application Of Neural Networks In Spaceflight Control Systems, Pavel Galchenko

Doctoral Dissertations

“Spaceflight systems can enable advanced mission concepts that can help expand our understanding of the universe. To achieve the objectives of these missions, spaceflight systems typically leverage guidance and control systems to maintain some desired path and/or orientation of their scientific instrumentation. A deep understanding of the natural dynamics of the environment in which these spaceflight systems operate is required to design control systems capable of achieving the desired scientific objectives. However, mitigating strategies are critically important when these dynamics are unknown or poorly understood and/or modelled. This research introduces two neural network methodologies to control the translation and rotation …

Characterization And Utilization Of Alkali-Activated Concrete For Sustainable Infrastructures, Eslam Gomaa

Doctoral Dissertations

“This study has investigated the feasibility of using locally available fly ashes (FAs) to synthesize alkali-activated concrete (AAC) for different structural and repair applications. Using AAC made of 100% FA reduces global CO2 emissions, saves energy, and decreases raw material consumption during the production process of ordinary Portland cement. Class C FAs, sourced from Labadie, Jeffery City, Kansas City, Thomas Hill, and Sikeston power plants in the state of Missouri, were used to synthesize the AAC. Sodium silicate (SS), Na2SiO3, and sodium hydroxide (SH), NaOH were used as the alkali activators. Slag, crumb rubber, and air-entraining admixture were used as …

Innovative Approach To Use Guayule Resin As A Bio-Based Asphalt Alternative, Ahmed Hemida

Doctoral Dissertations

"Asphalt cement will not last long as the world encounters a diminishment in crude oil. Novel resources can contribute to replacing asphalt with the sustainable, flexible pavement. This study presented guayule resin (guayule) as an innovative bio-based asphalt alternative. Ground tire rubber was used as an asphalt enhancer. To judge the guayule's contribution, guayule-based binders were investigated and compared to control asphalt and asphalt-rubber binders. Binders were assessed according to comprehensive Superpave criteria and advanced rheological tests. Component analysis was performed to link the microscale level with the macroscale level. To validate the novel binder, satisfying mix performance tests were …

Characterizing And Modeling Methods For Power Converters, Anfeng Huang

Doctoral Dissertations

“Stable power delivery is becoming increasingly important in modern electronic devices, especially in applications with stringent requirements of its form factor. With the evolution of technology, the switching frequency in a power converter is pushed to a higher frequency range, e.g., several MHz or even higher, to decrease its size. However, the loss generated in the converter increases drastically due to the high switching frequency. In addition, a wide-band feedback controller is required to accommodate the high switching frequency in the converter. We focus on the characterization or modeling of the feedback control circuits and critical components in a switching …

Variational Data Assimilation For Two Interface Problems, Xuejian Li

Doctoral Dissertations

“Variational data assimilation (VDA) is a process that uses optimization techniques to determine an initial condition of a dynamical system such that its evolution best fits the observed data. In this dissertation, we develop and analyze the variational data assimilation method with finite element discretization for two interface problems, including the Parabolic Interface equation and the Stokes-Darcy equation with the Beavers-Joseph interface condition. By using Tikhonov regularization and formulating the VDA into an optimization problem, we establish the existence, uniqueness and stability of the optimal solution for each concerned case. Based on weak formulations of the Parabolic Interface equation and …

Numerical Simulation Study Of Gel Treatment For Conformance Control From Lab To Field, Jianqiao Leng

Doctoral Dissertations

“Gel treatment has been widely applied to control reservoir conformance and thus improve the sweep efficiency of injection fluids. Quite a few numerical simulations have been conducted to investigate the factors impacting gel treatment and assist to optimize treatment design and predict the performance. However, there exists significant barrier between the simulation approaches and lab experiments. In this study, two comprehensive reviews have been conducted to identify the gaps between lab and current simulations for in-situ polymer treatment and preformed particle gel treatment, separately.

Based on the identified gaps, the effect of a few major factors which are very important …

The Kanarra Fold-Thrust System -- The Leading Edge Of The Sevier Fold-Thrust Belt, Southwest Utah, William Joseph Michael Chandonia

Doctoral Dissertations

“The Jurassic to Eocene Sevier fold-thrust belt is the subject of continued scientific curiosity in tectonics, stratigraphy, and industry. Understanding its development in southwest Utah is hindered in part due to the multiple origins proposed for the Kanarra anticline, a major leading edge structure -- a drag fold along the Hurricane fault, Laramide monocline, Sevier fault propagation fold, or a combination of these -- which have confused its tectonic significance and regional context. This confusion results from the structural complexity of its exposed eastern limb, as well as displacement and burial of its crest and western limb beneath Neogene sediments …

Array Signal Processing For Source Localization And Enhancement, Sohel J. Patel

Doctoral Dissertations

“A common approach to the wide-band microphone array problem is to assume a certain array geometry and then design optimal weights (often in subbands) to meet a set of desired criteria. In addition to weights, we consider the geometry of the microphone arrangement to be part of the optimization problem. Our approach is to use particle swarm optimization (PSO) to search for the optimal geometry while using an optimal weight design to design the weights for each particle’s geometry. The resulting directivity indices (DI’s) and white noise SNR gains (WNG’s) form the basis of the PSO’s fitness function. Another important …

Advances And Applications In High-Dimensional Heuristic Optimization, Samuel Alexander Vanfossan

Doctoral Dissertations

“Applicable to most real-world decision scenarios, multiobjective optimization is an area of multicriteria decision-making that seeks to simultaneously optimize two or more conflicting objectives. In contrast to single-objective scenarios, nontrivial multiobjective optimization problems are characterized by a set of Pareto optimal solutions wherein no solution unanimously optimizes all objectives. Evolutionary algorithms have emerged as a standard approach to determine a set of these Pareto optimal solutions, from which a decision-maker can select a vetted alternative. While easy to implement and having demonstrated great efficacy, these evolutionary approaches have been criticized for their runtime complexity when dealing with many alternatives or …

Evaluation Of Recrosslinkable Preformed Particle Gel (Rppg) As A Fluid Loss Control Material During Drilling Operations, Mohamed Saad M. Ahdaya

Doctoral Dissertations

"One of the most intense, expensive, and time-consuming problems during drilling operations is the loss of circulation, which could result in several consequences, including wellbore collapse, fluid inflow, formation damage, environmental issues, and nonproductive time. This research aims to evaluate novel materials that can mitigate lost circulation and overcome the limitation of other materials. In this research, a comprehensive evaluation of a re-crosslinkable preformed particle gel (RPPG) has been conducted to determine the extent to which it can be used to control drilling fluid losses during drilling operations. The RPPG consists of swellable gel particles that can self-crosslink to form …

Novel Sensor Platforms Based On Fabry-Perot Resonators For Applications In Environmental Geophysics, Jing Guo

Doctoral Dissertations

"Fabry-Perot resonator sensors have been widely used for various physical and chemical measurements owing to their unique advantages over traditional sensors such as high measurement resolution, mechanically robust, and distributed sensing capabilities. This dissertation focuses on the development of robust fiber optic microwave sensors based on Fabry-Perot resonator mechanism for real-time applications in environmental geophysics.

Firstly, a novel Extrinsic Fabry-Perot Interferometer (EFPI)-based fiber-optic sensor for force measurement using a pre-buckled beam was demonstrated. The axial displacement is transferred and amplified to a horizontal deflection at the middle of the buckled beam, leading to a relatively significant change in the Fabry-Perot …

Synthesis, Characterization And Chemistry Of Two-Dimensional Transition Metal Carbides And Nitrides (Mxenes), Shuohan Huang

Doctoral Dissertations

"MXenes represent a relatively new and quickly growing family of two-dimensional (2D) early transition-metal carbides and nitrides first synthesized in 2011 from bulk layered crystalline MAX phases. Because of their 2D structure and unique combination of high conductivity and hydrophilicity, MXenes have raised a significant interest for various applications. However, it has been found that in some cases colloidal MXene flakes are not stable and can spontaneously degrade on a time scale from hours to days. In this work, we investigate the crucial factors for MXene degradation and demonstrate gas analysis as a powerful method to gain further insights into …

Distributed Fiber-Optic Temperature Sensors For Applications In The Steel Industry, Muhammad Roman

Doctoral Dissertations

"Steelmaking facilities require continuous temperature measurements throughout the manufacturing process to ensure consistent product quality and high productivity. Motivated by the limitations of conventional temperature sensors, distributed fiber-optic sensors (DFOS) were developed and deployed for various applications in the steel industry. Fiber-optic sensors offer various advantages over conventional sensors, such as the miniaturized size of the optical fiber, immunity to electromagnetic interferences, capability for multiplexing and distributed sensing, and the ability to withstand harsh environments.

Firstly, high-resolution Rayleigh backscattering based DFOS were demonstrated as potential solutions for temperature measurements in steelmaking processes by performing experimental simulations. Additionally, aluminum casting experiments …

Joining Of Ultra-High Temperature Ceramics To The Same And Refractory Metals Via Fusion Welding, Jecee Jarman

Doctoral Dissertations

"This research focuses on the joining of ultra-high temperature ceramics to either themselves or refractory metals/alloys via fusion welding and the mechanical strength of produced joints. The ceramics studied consisted of compositions within a diboride-carbide-carbide ternary system while metals studied consisted of molybdenum and a molybdenum alloy. SiC-ZrB2-ZrC ceramics on a binary join between pure SiC and the ternary eutectic composition were found to be weldable when SiC content was below ~57.5 vol%. Compositions above 57.5 vol% SiC were unweldable based on pitting and off-gassing behavior. Welded strength of ceramics was ~180-300 MPa in the SiC-ZrB2-ZrC ternary eutectic composition, ~180-220 …

Peritectic Behavior Detection And Prediction In Fe-C-Si-Mn-Al System, Damilola Balogun

Doctoral Dissertations

"The non-uniformity of shell growth in the continuous casting of peritectic steels constitutes a major barrier to the commercial production of many steel grades such as Advanced high strength steels (AHSS), transformation induced plasticity (TRIP) steels, abrasion-resistant steels, advanced armor plate steels, and many newly proposed steel grades that contain high levels of silicon, manganese, and aluminum.

The shell growth non-uniformity experienced in the continuous casting of peritectic steels results in the formation of defects in the as-cast slab and therefore increases the operating risk from cast aborts and breakouts. The ability to predict and avoid peritectic behavior at the …

Development And Testing Of A New Air-Assisted Flare System For Low Flow Conditions, Hayder Alhameedi

Doctoral Dissertations

"Flare systems provide a safe, efficient, and reliable way to treat unwanted flammable gases that come from relief devices of various chemical processing equipment to ensure the safety of personnel and equipment. Flare systems are classified according to the assist media type as non-assisted (utility), steam-, air-, and pressure-assisted flares. The assist medium enhances mixing between flare gases and surrounding air and induces more air into the combustion zone. An air-assisted flare system is the preferred flare type in regions where steam is unavailable or is costly to supply or ambient temperatures are too low. The environmental protection agency (EPA) …

Data-Driven Modeling And Simulations Of Seismic Waves, Yixuan Wu

Doctoral Dissertations

"In recent decades, nonlocal models have been proved to be very effective in the study of complex processes and multiscale phenomena arising in many fields, such as quantum mechanics, geophysics, and cardiac electrophysiology. The fractional Laplacian(−Δ)^��/2 can be reviewed as nonlocal generalization of the classical Laplacian which has been widely used for the description of memory and hereditary properties of various material and process. However, the nonlocality property of fractional Laplacian introduces challenges in mathematical analysis and computation. Compared to the classical Laplacian, existing numerical methods for the fractional Laplacian still remain limited. The objectives of this research are …

Engineering Ni/Al2o3 Catalysts By Atomic Layer Deposition For Methane Reforming, Baitang Jin

Doctoral Dissertations

"Dry reforming of methane (DRM) could be a promising choice to utilize natural gas (mainly methane or CH₄), recycle captured CO₂, and produce valuable syngas. Promoters (e.g., CeO₂ and MgO) on Ni/Al₂O₃ prepared by atomic layer deposition (ALD) and ALD-prepared ultrathin overcoating (e.g., ZrO₂ and CeO_x) on Ni/Al₂O₃ prepared by incipient wetness method were investigated for methane reforming.

MgO and CeO₂ prepared by traditional incipient wetness method were used to promote the performance of ALD-prepared Ni nanoparticles (NPs) supported on four-channel α-Al₂O_{3 …}

Electrocatalytic Processes For Energy Storage & Conversion, Apurv Saxena

Doctoral Dissertations

"The continuous excessive usage of fossil fuels has resulted in its fast depletion leading to an escalating energy crisis as well as several environmental issues leading to increased research towards sustainable energy conversion. Electrocatalysts play crucial role in the development of numerous novel energy conversion devices including fuel cells and solar fuel generators.

High-efficiency and cost-effective catalysts are required for large-scale implementation of these new devices. Over the last few years transition metal chalcogenides have emerged as highly efficient electrocatalysts for several electrochemical devices such as water splitting, carbon dioxide electroreduction and, solar energy converters. These transition metal chalcogenides exhibit …

Corrosion Resistance Performance Investigation Of Mild Steel Bar Coated With Magnesium Phosphate Cement Paste, Fan Zhang

Doctoral Dissertations

"In this research study, the anti-corrosion mechanism of reinforcement embedded in magnesium potassium phosphate cement (MKPC) is explored. In addition, one type of additives, metakaolin, and one type of retarder, boric acid, are employed in MKPC to modify its properties in order to further investigate corrosion resistance and to achieve mass-production coating reinforcement at the work site. This coating method may be practical for some underwater construction and some traditional reinforcement concrete structures to reduce the reinforcement corrosion rate and to eventually extend service life in both repair and new construction applications.

By comparing the electrochemical properties of bare ribbed …

Surface Modification To Improve The Electrochemical Performance Of Cathode Materials For Lithium-Ion Batteries And Sodium-Ion Batteries, Han Yu

Doctoral Dissertations

"The specific capacity of active materials as well as their cycling stability are the main limiting factors for the performance of lithium-ion batteries (LIBs) and sodium-ion batteries (SIB). Atomic layer deposition (ALD) is considered as a promising surface modification method to enhance the electrochemical performance of active materials for LIBs and SIBs.

In this research, we are committed to using ALD to modify the cathode materials of LIB, by coating different films on the surface of different cathode materials and constructing a stable and favorable interface layer for lithium-ion transport, so that we can protect the active materials from the …

Processing To Enable Direct-Write Additive Manufacturing Of Ceramics And Ceramic Composites, Austin Martin

Doctoral Dissertations

"This research focuses on the processing of novel feedstocks for and during direct-write additive manufacturing (AM), specifically the direct ink writing (DIW) and Ceramic On-Demand Extrusion (CODE) manufacturing processes, in order to produce ceramic and ceramic-based composite components. Strongly dispersed, concentrated (φ = 0.42), nanoparticle (d₅₀ ~0.3 µm), zirconia (ZrO₂) pastes were used to print densely filled, large continuous volume (≳ 1 cm³) ceramic components. An elastic shear modulus (G’) of 56,000 Pa and yield stresses between 6 and 10 Pa allowed for printed components of 34.5 mm in height over 115 layers without slumping …