Engineering Commons^™

Establishing Links Between Safety Culture, Climate, Behaviors, And Outcomes Of Long-Haul Truck Drivers, Carlton Washburn

Doctoral Dissertations

“This research examines the safety relationships between safety culture, safety influences, safety climate, and safety outcomes for long-haul truck drivers. The relationships focus on the intersection of the electronic logging device (ELD) technology, regulations, and truck drivers that fall into the lone-worker category. Truck drivers were interviewed to understand their beliefs, attitudes, practices, values, and behavior patterns aligned with the phase in of the ELD system. Large truck crashes during the same time period were analyzed to understand associations. Outcomes included both a safety culture and climate were established for long-haul truck drivers. Both positive and negative safety behaviors were …

Fiber Reinforced Polymer Bar Investigation: Long-Term In-Situ Durability And Bond Strength Assessment In Conventional And Sustainable Concrete, Ali Fadhil Al-Khafaji

Doctoral Dissertations

"Corrosion of steel reinforcement and carbon dioxide emissions are two major global problems. Different methods, techniques, and materials have been implemented to mitigate these problems. Glass fiber-reinforced polymer (GFRP) bar presents itself as a solid alternative to replace conventional steel reinforcement owing to its fantastic features in resisting corrosion. Its demand is progressively increasing. Cement-based concrete, on the other hand, is not eco-friendly due to the excessive amount of carbon dioxide (CO₂) emissions yielded from its cement production. One of the alternatives used to mitigate the use of cement in concrete is fly ash. Fly ash is considered …

Analysis Of Turbulence Model Uncertainty For Canonical Flow Problems Including Shock Wave Boundary Layer Interaction Simulations, Aaron James Erb

Doctoral Dissertations

"The purpose of this research is to present results of an uncertainty and sensitivity analysis study of commonly used turbulence models in Reynolds-Averaged Navier-Stokes (RANS) codes due to the epistemic uncertainty in closure coefficients for a set of turbulence model validation cases that represent the structure of several canonical flow problems. The study focuses on the analysis of a 2D zero pressure gradient flat plate, a 2D wall mounted hump, and an axisymmetric shock wave boundary layer interaction, all of which are well documented on the NASA Langley Research Center Turbulence Modeling Resource website. The Spalart-Allmaras (SA), the Wilcox (2006) …

Theoretical Study Of Magnetic Particles In A Shear Flow Subjected To A Uniform Magnetic Field, Christopher A. Sobecki

Doctoral Dissertations

"Magnetic manipulation of non-spherical magnetic microparticles is important for applications in shape-based and magnetic-based separations such as waste management, disease diagnostics, drug delivery, and mining. Manipulations of magnetic microparticles also include chain formation to assemble compositions for electronics, drug loading designs, and magnetorheological fluids for smart armor, hydraulic brakes, and dampers. In microfluidic devices, separation-formation-effectiveness depends on the shape of the channel, the shear rate, and the magnetic field strength and direction.

Particle separation and chain formation involved highly complex and computational expense-demanding studies in microfluidic devices, magnetic fields, and particle- particle/wall interactions. This research took complex experimental studies and …

Studies On Tornado-Structure Interactions And Guidance On Design Tornadic Wind Loading, Zhi Li

Doctoral Dissertations

“Tornadoes are violent natural hazards that could caused significant property loss and fatalities. Statistical data indicates that most fatalities during tornado incidents were caused by the building failure under tornadoes. For example, in the 2011 Joplin Tornado, 161 people were killed, and 84 percent of the fatalities were related to the failure of buildings. In addition, most of the significant, tornado-induced property loss and fatalities are relevant to the tornadoes passing through the densely populated regions. Besides buildings, bridges were also severely damaged or destroyed by tornadoes in the United States. To reduce the tornado-induced loss, it is imperative to …

Computational Intelligent Impact Force Modeling And Monitoring In Hislo Conditions For Maximizing Surface Mining Efficiency, Safety, And Health, Danish Ali

Doctoral Dissertations

"Shovel-truck systems are the most widely employed excavation and material handling systems for surface mining operations. During this process, a high-impact shovel loading operation (HISLO) produces large forces that cause extreme whole body vibrations (WBV) that can severely affect the safety and health of haul truck operators. Previously developed solutions have failed to produce satisfactory results as the vibrations at the truck operator seat still exceed the “Extremely Uncomfortable Limits”. This study was a novel effort in developing deep learning-based solution to the HISLO problem.

This research study developed a rigorous mathematical model and a 3D virtual simulation model to …

Evaluation Of Robust Epoxy Resin Sealants For Wellbore Integrity Applications, Mohammed Mousa M Alkhamis

Doctoral Dissertations

"During the drilling and completion phases of oil and gas wells, cement is placed in the wellbore as a barrier between the casing and the formation. All casing strings must be cemented to protect and support the casing, and to isolate production zones. The primary cement must prevent the wellbore fluids from migrating in an annular flow path so as to allow the wells to be utilized without any control problems. The primary cement may fail to deliver full zonal isolation due to several reasons such as insufficient mud removal before the cementing, casing expansion, and contraction, high fluid losses, …

Evaluation Of Excavated Surface Irregularities And Hardness Of Mechanical Excavations And Their Relationship With Excavator Performance, Prosper Evaristus Akansah Ayawah

Doctoral Dissertations

"This research involved lab and numerical excavation of a clastic sedimentary rock (Roubidoux Sandstone) using a long-bladed disc cutter in a Linear Rock Cutting Machine (LCM) with the aim of establishing relationships between the cutting parameters, excavated surface parameters (underbreaks, overbreaks and hardness), and performance parameters (specific energy and cutting rate). Three-dimensional cutting forces were recorded during the linear cutting. A structured laser imaging system was used to image the excavated surfaces for the estimation of the irregularities (ridge volumes (RV) and overbreak volumes (OV)). The excavated surface hardness was measured using the N-type Schmidt hammer. The numerical simulation was …

Exposure Assessment Of Emerging Contaminants: Rapid Screening And Modeling Of Plant Uptake, Majid Bagheri

Doctoral Dissertations

"With the advent of new chemicals and their increasing uses in every aspect of our life, considerable number of emerging contaminants are introduced to environment yearly. Emerging contaminants in forms of pharmaceuticals, detergents, biosolids, and reclaimed wastewater can cross plant roots and translocate to various parts of the plants. Long-term human exposure to emerging contaminants through food consumption is assumed to be a pathway of interest. Thus, uptake and translocation of emerging contaminants in plants are important for the assessment of health risks associated with human exposure to emerging contaminants. To have a better understanding over fate of emerging contaminants …

Properties And Structures Of Alkali Molybdenum Iron Phosphate Glasses For Nuclear Waste Immobilization, Jincheng Bai

Doctoral Dissertations

"The development of glasses to immobilize nuclear wastes requires a detailed understanding of how composition affects the critical properties required to design wasteforms, including thermal stability and chemical durability. Those properties depend on the molecular-level structures of the glasses. The principal objective of this research was to develop a comprehensive understanding of the composition-structure-property relationships, including the effects of processing conditions, for glasses in the alkali- molybdenum-iron-phosphate systems that could then be used to inform the development of wasteforms of interest to the US Department of Energy.

The molecular-level structures of the alkali molybdenum iron phosphate glasses were analyzed by …

Fabrication, Characterization Of High-Entropy Alloys And Deep Learning-Based Inspection In Metal Additive Manufacturing, Wenyuan Cui

Doctoral Dissertations

"Alloying has been used to confer desirable properties to materials. It typically involves the addition of small amounts of secondary elements to a primary element. In the past decade, however, a new alloying strategy that involves the combination of multiple principal elements in high concentrations to create new materials called high- entropy alloys (HEAs) has been in vogue. In the first part, the investigation focused on the fabrication process and property assessment of the additive manufactured HEA to broaden its engineering applications. Additive manufacturing (AM) is based on manufacturing philosophy through the layer-by-layer method and accomplish the near net-shaped components …

Thermomechanical Simulation And Process Optimization For Hot Rolling Of Steel, Shouvik Ganguly

Doctoral Dissertations

"Hot rolling is a manufacturing process that involves large material deformation, complicated geometries, contact conditions and non-uniform temperature gradients. Steel industries are motivated to prevent hot rolled steel products to be defect free and with desired shape and size. In order to simulate the process accurately, it is essential that the material model for steel accounts for the viscoplasticity and changes in properties that occur in steel at elevated temperatures as grain growth and recrystallization.

The healing of existing voids during hot rolling was investigated using finite element simulations. Voids are highly undesirable as they not only degrade the product …

Investigating The Effect Of Operating Condition On Esd-Induced Soft-Failures, Omid Hoseini Izadi

Doctoral Dissertations

"Conflicting observations have been found in the literature regarding the effect of operating conditions on ESD (electrostatic discharge) susceptibility. While some studies have suggested a strong correlation between the two, others observed little to no correlation. In this work, a systematic study has been carried out suggesting the existence of a strong correlation between the ESD susceptibility and operating conditions. It is found that the root cause of this conflict is random ESD noise injection. A measurement approach is proposed to synchronize the noise injection with the system activity such as high/low CPU load. In this approach, the current consumption …

Fabrication Of 304l Stainless Steel And Aluminum Parts By Laser Foil Printing And Process Automation, Chia-Hung Hung

Doctoral Dissertations

"This work presents research conducted on a novel metal additive manufacturing process, called Laser Foil Printing (LFP), to fabricate metal parts with various geometries layer by layer using metal foil as the feedstock. To investigate the processability and characteristics of LFP for fabricating metal parts, the materials included 304L stainless steel and Al-1100 aluminum alloy. The LFP process parameter windows for both 304L and Al-1100 were determined, and the optimal process parameters with stable formation of the melt pools were selected to fabricate dense metal parts. The microstructure and properties of LFP-fabricated parts were characterized and analyzed using tensile testing, …

Characterization Of Alaskan Modified Asphalt Binders And Mixtures, Jun Liu

Doctoral Dissertations

"Modified asphalt binders and mixtures have been used more in recent years in Alaska. However, there has not been systematic characterization and performance data development for these materials. This study intends to systematically characterize the Alaskan asphalt binders and mixtures and identify the performance benefits of these materials through laboratory tests and field sections monitoring. The research contains five sections: 1) a comprehensive characterization on the morphologies, chemical and rheological properties of modified asphalt binders and mechanical properties of asphalt mixtures with these modified asphalt binders. The lab testing results were further confirmed through field surveys of recent paving projects …

Integrated Solar And Ess Ac/Dc Systems For Various Grid Applications, Phani Ratna Vanamali Marthi

Doctoral Dissertations

"Modular multilevel converters (MMC) have gained prominence for high power applications in recent years due to their technical merits such as voltage scalability, harmonic performance, and high efficiency. Integration of renewable energy sources such as solar photovoltaic (PV) systems and energy storage systems (ESS) to the grid using power electronic (PE) resources is increasing due to the techno-economic successes achieved by such systems. Following these developments, the integration of MMCs with PV plants and ESS systems is one of the dynamic research avenues being pursued. Along these lines, an integrated development of PV plants, ESS, and alternating- and direct-current (ac/dc) …

The Implementation Of Energy Sharing Using A System Of Systems Approach, Julia Morgan

Doctoral Dissertations

"There is an increasing demand for renewable energy and consumers need more procurement options to meet their needs. Energy sharing provides a peer-to-peer (P2P) marketplace where prosumer electricity is redistributed to fellow energy-sharing community participants. This redistribution of prosumer electricity provides consumers with additional electricity suppliers, while also decreasing the load on the utility company. Though significant progress has been made regarding research and implementation of energy sharing, there is still room for growth when evaluating energy-sharing communities and defining appropriate community coordination based on end-user needs. The first contribution in this work identified nine characteristics of energy-sharing communities as …

Stability Analysis Of Microgrids Using Markov Jump Linear Systems, Gilles Mpembele

Doctoral Dissertations

"This research discusses stochastic models for a microgrid operating between standalone and grid-tied modes. The transitions between different modes are modeled as a continuous-time Markov chain (CTMC). In each operating mode, the system is modeled using conventional differential algebraic equations (DAEs), linearized around some equilibrium point.

In Topic-I, a model is developed using the Stochastic Hybrid Systems (SHSs) formulation. The microgrid is modeled as a Markov jump linear system (MJLS), which is a type of SHS in which the discrete events evolve according to a Continuous Time Markov Chain (CTMC). The model allows for the derivation of Ordinary Differential Equations …

Scheduling Based Optimization In Software Defined Radio And Wireless Networks, Nathan Daniel Price

Doctoral Dissertations

"The objective of this work is to enable dynamic sharing of software-defined radio (SDR) transceivers through the concepts of hardware virtualization and real-time resource management. SDR is a way to build a digital radio that consists of a software back-end for digital signal processing (DSP) and an analog front-end transceiver for waveform generation and reception. This work proposes the use of a virtualization layer to decouple back-end SDR software from front-end transceivers. With this arrangement, front-ends are said to be virtualized, and it becomes possible to share a limited number of front-ends among many SDR back-ends through different multiplexing techniques. …

Investigation Of Packed Bed And Moving Bed Reactors With Benchmarking Using Advanced Measurement And Computational Techniques, Binbin Qi

Doctoral Dissertations

"Trickle bed reactors (TBR), as typical packed bed reactors (PBR), are widely used in various fields. Very limited information regarding the flow behaviors, hydrodynamic, and mathematical models in extrudate catalyst shapes, such as cylinders, trilobes, and quadrilobes, can be found in literatures because the major focus was on spherical shape. Therefore, a hybrid pressure drops and liquid holdup phenomenological model for extrudate catalyst shapes was developed based on two-phase volume averaged equations, which showed high accuracy against experimental data. The maldistribution and dynamic liquid holdup were investigated in quadrilobe catalyst using gamma-ray computed tomography. A pseudo-3D empirical model was developed …

Source Reconstruction In Near Field Scanning For Rfi Application, Hosseien Rezaei

Doctoral Dissertations

"This research is divided into three major topics. The first topic, mechanical magnetic field generator for communication in the ULF range, is discussed in the first paper. The second topic, source reconstruction in near field scanning for RFI application, is discussed over the course of two papers. The third topic, analysis of imbalanced 2 or 3 Wire VHF LISN, is discussed in the last two papers.

In the first topic, the possibility to use a mechanical system (a rotating magnet) as a source (generator or antenna combined) of the ULF magnetic field is investigated. Ultralow frequency (ULF) communication systems have …

Modeling And Analyzing Parasitic Parameters In High Frequency Converters, Mohamad Saleh Sanjari Nia

Doctoral Dissertations

"This research focuses on electromagnetic interference (EMI) / electromagnetic compatibility (EMC) design and analysis in power electronics systems. To limit the EMI under the standards, different methods and strategies are investigated. Parasitic parameters of high frequency (HF) transformer are analyzed using a novel analytical method, finite element method (FEM), and experimental measurements for different structures and windings arrangements. Also, the magnetic field, electric field, electric displacement, and electric potential distribution are simulated and analyzed. Moreover, a high voltage system is considered and analyzed to improve the EMC. The EMI propagation paths are analyzed. The EMI noise level of the system …

Thermophysical Properties Of Nominally Phase Pure Boride Ceramics, Austin D. Stanfield

Doctoral Dissertations

"This research focusses on the thermophysical properties of nominally phase pure boride ceramics. As interest in ultra high temperature ceramics increases due to a renewed interest in hypersonic flight vehicles and with the expanding materials design space accompanying interest in high entropy materials, it is imperative to understand the intrinsic properties of boride ceramics. By reducing Hf content in ZrB₂ from the natural abundance, ~1.75 at% in this case, to ~100 ppm, thermal conductivity increased from 88 W/m·K to 141 W/m·K. Removal of Hf allowed the thermal conductivity of ZrB₂ with small transition metal solute additions to be …

Pdn Modeling For High-Speed Multilayer Pcb Boards And Decap Optimization Using Machine Learning Techniques, Ling Zhang

Doctoral Dissertations

"In power distribution networks (PDN), there are two main challenges nowadays. One challenge is how to efficiently model and calculate the impedance for arbitrary-shape and multi-layer PDN systems. The second challenge is the optimization of decoupling capacitors in the pre-layout stage. This dissertation proposes novel solutions to these two challenges. To tackle the first challenge, a boundary element method (BEM) is utilized to calculate the quasi-static inductances between vertical vias for arbitrary-shape planes. Then a specialized circuit solver is developed to solve the equivalent circuit of inductances and capacitances for multi-layer PDN structures. Also, a contour integral method (CIM) is …

Quantum Inspired Concepts In Decision Making, Qizi Zhang

Doctoral Dissertations

"In this study, several new applications of quantum-inspired techniques are presented to advance the state of the art in decision making. In the first part, a quantum boost scheme for multiple-model filters based on extended Grover’s algorithm is presented for fault detection and parameter estimation. The quantum boost scheme accelerates the convergence of the posterior probabilities in the multiple-model filter. Stability proofs for the quantum boost scheme is presented and its performance is analyzed using benchmark examples. In the second part, the scope of application is extended to modeling human decision making. The open quantum system cognition model is applied …

Fiber Optic Sensors For Industry And Military Applications, Yiyang Zhuang

Doctoral Dissertations

"Fiber optic sensors (FOSs) have been widely used for measuring various physical and chemical measurands owing to their unique advantages over traditional sensors such as small size, high resolution, distributed sensing capabilities, and immunity to electromagnetic interference. This dissertation focuses on the development of robust FOSs with ultrahigh sensitivity and their applications in industry and military areas.

Firstly, novel fiber-optic extrinsic Fabry-Perot interferometer (EFPI) inclinometers for one- and two-dimensional tilt measurements with 20 nrad resolution were demonstrated. Compared to in-line fiber optic inclinometers, an extrinsic sensing motif was used in our prototype inclinometer. The variations in tilt angle of the …

Infrastructure Systems Modeling Using Data Visualization And Trend Extraction, Jacob Marshal Hale

Doctoral Dissertations

“Current infrastructure systems modeling literature lacks frameworks that integrate data visualization and trend extraction needed for complex systems decision making and planning. Critical infrastructures such as transportation and energy systems contain interdependencies that cannot be properly characterized without considering data visualization and trend extraction.

This dissertation presents two case analyses to showcase the effectiveness and improvements that can be made using these techniques. Case one examines flood management and mitigation of disruption impacts using geospatial characteristics as part of data visualization. Case two incorporates trend analysis and sustainability assessment into energy portfolio transitions.

Four distinct contributions are made in this …

Scaling, Experiments, And Simulations Of Condensation Heat Transfer For Advanced Nuclear Reactors Safety, Palash Kumar Bhowmik

Doctoral Dissertations

“The purpose of this research was to perform scaled experiments and simulations to validate computational fluid dynamics (CFD) and empirical models of condensation heat transfer (CHT) for the passive containment cooling system (PCCS) of Small Modular Reactors (SMRs). SMRs are the futuristic candidates for clean, economic, and safe energy generation; however, reactor licensing requires safety system evaluations, such as PCCS. The knowledge in the reviewed relevant literature showed a gap in experimental data for scaling SMR’s safety systems and validating computational models. The previously available test data were inconsistent due to unscaled geometric and varying physics conditions. These inconsistencies lead …

Protection Of Modern Distribution Systems, Fahd Amin Hariri

Doctoral Dissertations

“Motivated by the potential for improvements in the electric distribution system’s protection schemes, this work examined the challenges facing protection schemes due to the integration of Distributed Generators (DGs). Traditional protection schemes for radial distribution systems were designed based on the unidirectional power flow from the source down to the loads. Protective devices typically use are overcurrent relays, autoreclosers, fuses, and circuit breakers. However, these protective schemes may no longer be sufficient to ensure correct operation in the new era of distribution systems integrated by DGs. This research investigated the impact of DGs that might mislead the protection schemes in …

Emi Characterization For Power Supplies And Machine Learning Based Modeling In Emc/Si, Jiayi He

Doctoral Dissertations

"Signal integrity (SI) and electromagnetic interference (EMI) are essential for consumer electronics and high-speed server applications. It is necessary to do EMI and SI modeling at the design stage. In this research, several modeling approaches for EMI and SI problems are proposed. By using measurement-based modeling method, the mechanism of conducted emissions (CE) on ac to dc power supplies in an LED TV is analyzed. A system-level transient simulation model is built to predict the conducted emission (CE). To characterize the equivalent dipole moment sources in RFI and EMI problems, a dipole source reconstruction method based on machine learning techniques …