Engineering Commons^™

On The Effects Of Additive Manufacturing Process Parameters On The Performance Of Hastelloy-X: A Neutron Diffraction Experiment And Crystal Plasticity Finite Element Model, Ahmed Aburakhia

Electronic Thesis and Dissertation Repository

Additive manufacturing (AM) is increasingly becoming one of the favourable manufacturing techniques in various industries, such as transportation and energy. The reason for the extensive use of AM lies in the ability to use a wide range of process parameters for manufacturing engineering parts with complex geometries that cannot be effectively manufactured using traditional methods such as casting or forging. Understanding the role of process parameters is crucial for developing predictive models, as well as for manufacturing engineering components with the desired properties.

This research aims to characterize the influence of AM process parameters on the deformation mechanisms of Hastelloy-X, …

Coexistence Of Wi-Fi And 5g Nr-U In The Unlicensed Band, Sara Saud Zimmo

Electronic Thesis and Dissertation Repository

The communications industry continues to evolve to meet the ever-growing demands of fast connectivity and higher energy-efficiency and has emerged the concept of Internet of Things (IoT) systems. IoT devices can be run on Wi-Fi or cellular network, helping businesses to receive higher return on investments.

As billions of devices on cellular networks operate on the limited licensed spectrum, it is becoming scarcer. Mobile network operators are investigating to access the immense unlicensed spectrum, on which Wi-Fi is prominently operated. Managing this coexistence between the cellular and Wi-Fi networks poses several challenges.

One challenge is the spectrum sharing that affects …

Evaluation Of Fresh Groundwater Resources And Nitrogen Discharge To The Coastal Lagoon Of An Atoll Island, James D. Gale

Electronic Thesis and Dissertation Repository

Atoll island communities face socio-economic challenges together with environmental pressures imposed by climate change that are causing increased water quality degradation. Wastewater from domestic septic systems is released into the subsurface on Fongafale Islet, Tuvalu. It is unclear if this is contributing to high nitrogen (N) concentrations and eutrophication of the adjacent coastal lagoon. In this study, a variable-density groundwater flow and conservative contaminant transport model was developed in SEAWAT-2005 to simulate the salinity distribution and N transport through the Fongafale Islet aquifer. Model simulations evaluated the influence of tides, variable (interannual) recharge patterns, wastewater loading rates and wastewater source …

Development Of Photocatalytic Reactor System For Dye Degradation From Lab To Pilot Scale, Waleed Jadaa

Electronic Thesis and Dissertation Repository

The overall goal of the research is to develop a novel photocatalytic reactor system, namely, a bubble column photoreactor for the degradation of resistant pollutants, with a particular emphasis on azo dyes. To achieve the objective, different sub-objectives were performed employing lab and pilot-scale reactors with the application of simulated wastewater. Direct Blue (DB15) was used as a model compound for the azo dyes class for this study. Firstly, the influence of various variables such as pH, dye concentration, and catalyst loading to determine optimal combinations of DB15 removal. The experiments were conducted in a swirl flow photoreactor under the …

Computational Modelling Of Resin Infiltration And Curing In High Pressure Resin Transfer Molding, Anthony Paul Rexford Sherratt

Electronic Thesis and Dissertation Repository

Increased pressure on automotive manufactures to reduce overall greenhouse gas emissions from their vehicles has driven research into replacing conventional steel components with carbon fiber reinforced plastics (CFRP). This is due to their high weight specific properties and design freedom. High pressure resin transfer molding (HP-RTM), a derivative of resin transfer molding, is a manufacturing process for CFRP’s that offers high automation potential and low cycle times; critical properties of a manufacturing process for the automotive sector.

The goal of the present work is to increase the accuracy and reduce the computational overhead of current RTM infiltration and curing models. …

Exploring Valuable And Potentially Harmful By-Products Formed And/Or Released From Smouldering Treatment Of Sewage Sludge, Taryn Ashley Fournie

Electronic Thesis and Dissertation Repository

The presence of potentially toxic elements (PTEs) and emerging contaminants (e.g., per- and polyfluoroalkyl substances (PFAS)) makes sewage sludge management challenging. Due to their hazards, there is significant interest in thermal treatment technologies that can destroy these compounds, like incineration. However, incineration still poses several risks due to forming and/or releasing hazardous emissions (e.g., polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and PTEs). More recently, the use of smouldering has been introduced as a potential treatment technique for managing sewage sludge. Smouldering presents several advantages over traditional incineration due to its lower energy and pre-treatment requirements and potential for beneficial …

Self-Sustaining Smouldering Combustion Of Granular Activated Carbon Contaminated With Per- And Polyfluoroalkyl Substances – Fluorine Mass Balance And Enhanced Methods Of Mineralization, Brian Gerald Harrison

Electronic Thesis and Dissertation Repository

Per- and polyfluoroalkyl substances (PFAS) are a large group of anthropogenic compounds. Long-term use has led to widespread environmental contamination, and PFAS source zones will require cleanup.

Self-sustaining Treatment for Active Remediation (STAR) is a thermal treatment technology that employs smouldering combustion as a method of soil treatment. Smouldering can be self-sustaining and is thus more energy-efficient. Previous research applying STAR to PFAS-contaminated soil and granular activated carbon (GAC) showed promise, as PFAS were removed from soil.

This study clarified the potential of STAR as a treatment option for PFAS. This study is unique in how thoroughly it characterized the …

Early Biological Response Of Articular Cartilage To Hemiarthroplasty Wear, Debora Rossetti

Electronic Thesis and Dissertation Repository

Hemiarthroplasties typically result in accelerated wear of the preserved side of the joint, resulting in suboptimal clinical outcomes and limited longevity. This in vitro study investigated the effects of hemiarthroplasty implant curvature on the early biological response of articular cartilage measured by proteoglycan release, histology, and surface morphology. Cartilage from boar radiocarpal joints were worn by metal pins of varying radii of curvature (RoC) using a pin-on-plate wear simulator. Histology and proteoglycan assays showed no significant differences between RoC treatment groups, and proteoglycan assays showed increased proteoglycan release 72 hours after wear testing in worn cartilage specimens compared to control …

The Application Of Digital Volume Correlation Bone Strain Measurements In The Osteoarthritic Glenohumeral Joint, Jakub R. Targosinski

Electronic Thesis and Dissertation Repository

This thesis investigates the accuracy and precision of digital volume correlation measurements derived from micro-computed tomography imagery of interfaces in the upper extremity of clinical relevance, namely, the implant-cement-bone interface of glenoid implants used in total shoulder arthroplasties and the implant-bone interface of shoulder hemiarthroplasties. The works within derive relationships between measurement accuracy and precision and parameters of practical interest such as image quality and measurement spatial resolution. It also analyzes the effects of micro-computed tomography image artifact-inducing materials on the accuracy and precision of digital volume correlation-based measurements and the spatial relationship between distance between the artifacting material and …

Static Liquefaction And Critical State Mechanics Of Gold Mine Tailings Subjected To Different Stress Paths, Amir Reza Fotovvat

Electronic Thesis and Dissertation Repository

The mechanisms through which mine tailings fail have been the interests of many studies recently. In this series of studies, the flow liquefaction and instability behavior of gold mine tailings were examined within the framework of critical state soil mechanics. In the first study, the behavior of a gold mine tailings in stress paths involving extensional consolidation or shearing in extension was evaluated. Monotonic tests were carried out on isotropically and K_o-consolidated samples to assess the effect of stress-induced anisotropy and mode of shearing on the static liquefaction characteristics tailings. In the second study, the drained instability of …

Deep Learning For Load Forecasting With Smart Meter Data: Online And Federated Learning, Mohammad Navid Fekri

Electronic Thesis and Dissertation Repository

Electricity load forecasting has been attracting increasing attention because of its importance for energy management, infrastructure planning, and budgeting. In recent years, the proliferation of smart meters has created new opportunities for forecasting on the building and even individual household levels. Machine learning (ML) has achieved great successes in this domain; however, conventional ML techniques require data transfer to a centralized location for model training, therefore, increasing network traffic and exposing data to privacy and security risks. Also, traditional approaches employ offline learning, which means that they are only trained once and miss out on the possibility to learn from …

Photonic Crystal Edge Couplers For Sensing Applications, Michael A. Zylstra

Electronic Thesis and Dissertation Repository

Microelectromechanical systems (MEMS) have not only enabled the development of inexpensive sensors but have also improved their performance by lowering their mass thus enabling faster sensor response. However, there are limitations regarding the mass-scaling of conventional MEMS sensors that prevent further miniaturization. This makes the measurement of distributed forces with high spatiotemporal resolution challenging. Optical-based sensors provide low-volume confinement of electromagnetic energy and enable further mass-scaling. This thesis investigates the application of an optical deflection sensing mechanism that relies on the position dependent coupling between dielectric-like edge states on nearby photonic crystal slabs for the purposes of acoustic pressure, wall …

Investigation Of Cell Derived Nanoparticles For Drug Delivery And Osteogenic Differentiation Of Human Stem/Stromal Cells, Shruthi Polla Ravi

Electronic Thesis and Dissertation Repository

The successful repair of bone defects and injuries is enhanced by the delivery of osteoinductive factors, such as drugs, growth factors, and genetic material that can promote the osteogenic differentiation of stem/stromal cells into osteoblasts. Nanoparticle delivery systems are being studied to enable the sustained release of these factors but suffer from limitations such as cytotoxicity issues, poor loading capacity, and poor cellular uptake. In this project, we developed cell-derived nanoparticles (CDNs), a biomimetic nanoparticle delivery system with high drug loading efficiency, to deliver a glucocorticoid drug, dexamethasone (Dex), to promote the osteogenic differentiation of stem/stromal cells. The synthesized Dex-loaded …

Novel Fed-Batch Process With In-Situ Product Recovery For Glycerol Fermentation To Butanol Using Clostridium Pasteurianum, Ammi Jani

Electronic Thesis and Dissertation Repository

Butanol, a next-generation biofuel, can be produced by fermenting glycerol using Clostridium pasteurianum. To address product inhibition, an integrated system that combined a fed-batch process with pervaporation was assessed against conventional batch and fed-batch fermentations. This study showed that with the novel process configuration, the productive fermentation time could be extended, translating to a 2.4-fold and 1.9-fold increase in butanol production relative to baseline fed-batch and batch operation, respectively. Further, it was demonstrated that butanol concentrations were able to be maintained below inhibitory levels throughout the fermentation. Despite this outcome, metabolic oscillations were revealed, indicating instability in the process. The …

Application Of A Polynomial Affine Method In Dynamic Portfolio Choice, Yichen Zhu

Electronic Thesis and Dissertation Repository

This thesis develops numerical approaches to attain optimal multi-period portfolio strategies in the context of advanced stochastic models within expected utility and mean-variance theories. Unlike common buy-and-hold portfolio strategies, dynamic asset allocation reflects the investment philosophy of a portfolio manager that benefits from the most recent market conditions to rebalance the portfolio accordingly. This enables managers to capture fleeting opportunities in the markets thereby enhancing the portfolio performance. However, the solvability of the dynamic asset allocation problem is often non-analytical, especially when considering a high-dimensional portfolio with advanced models mimicking practical asset's return. To overcome this issue, this thesis presents …

Cooling Systems Analysis For Plastic Mold Injection Tools, Veronica Flores Quijada

Electronic Thesis and Dissertation Repository

The Plastic Injection Mold (PIM) industry has been searching for new technologies that improve the manufacturing of parts by reducing the production time and cost as well as increasing the quality of the product. The cooling systems in the PIM are designed initially to be straight-drilled into the mold, but this manufacturing process has traditionally not been very effective, since for molded parts with complex geometries, the cooling channels are not able to reach certain areas. This limitation has led the industry to develop conformal cooling channels that use the additive manufacturing technology, which allows the cooling channels to conform …

A Novel Ultrasound Elastography Technique For Evaluating Tumor Response To Neoadjuvant Chemotherapy In Patients With Locally Advanced Breast Cancer, Niusha Kheirkhah

Electronic Thesis and Dissertation Repository

Breast cancer is the second most diagnosed cancer in women, estimated to affect 1 in 8 women during their lifetime. About 10% to 20% of new breast cancer cases are diagnosed with locally advanced breast cancer (LABC). LABC tumors are usually larger than 5 cm and/or attached to the skin or chest wall. It has been reported that when such cases are treated with surgery alone, metastasis and mortality rates are high, especially where skin involvement or attachment to the chest wall is extensive. As such, efficient treatment for this kind of breast cancer includes neoadjuvant chemotherapy (NAC) to shrink …

Development Of High Performance Cathodes: From Liquid To Solid-State Batteries, Sixu Deng

Electronic Thesis and Dissertation Repository

Lithium-ion batteries (LIBs) are critical for the development of electric vehicles (EVs) because of their higher operating voltages compared to other energy storage technologies. However, the development of start-of-the-art LIBs touched the ceiling because of three main challenges: safety risks, limited energy density, and high cost. Accordingly, all-solid-state lithium-ion batteries (ASSLIBs) have recently emerged as promising alternative batteries for next-generation EVs because of their ability to overcome the drawbacks of conventional LIBs. Whether in conventional liquid LIBs or ASSLIBs, cathode materials are crucial in determining the overall performance. Hence, this thesis focuses on understanding the degradation mechanism of cathode interfaces …

Automated Segmentation Of The Inner Ear And Round Window In Computed Tomography Scans Using Convolutional Neural Networks, Kyle A. Rioux

Electronic Thesis and Dissertation Repository

Computed tomography (CT) scans are acquired prior to cochlear implant (CI) surgery. Three-dimensional segmentations of the inner ear (IE) and round window (RW) based on clinical CTs can improve the CI procedure. Software pipelines are presented here which employ convolutional neural networks to automatically segment the IE and RW. The first pipeline produces high resolution segmentations of the IE and RW in tightly cropped CTs. Mean IE Dice score and RW centroid error were 0.88, 0.57mm and 0.93, 0.18mm in implanted and non-implanted samples, respectively. The second pipeline automatically segments the IE in large field of view CTs of any …

Effect Of Structural Nonlinearities On Flutter Of Cable-Supported Bridges, Sébastien Maheux

Electronic Thesis and Dissertation Repository

It is well known that cable-supported bridges, like suspension bridges and cable-stayed bridges, are structures that are highly sensitive to wind. This is why there has been an important research effort over the past decades on aeroelastic instability phenomena in bridges like flutter. This has allowed the safe design of long-span bridges with respect to wind effects. Nonetheless, the analysis methods that have become the norm in the field of bridge engineering, such as flutter analysis and wind tunnel tests, rely on some simplifications to facilitate analysis. For example, they assume a linear structural behavior of the bridge structure. Therefore, …

Carbon Injection To Support In-Situ Smouldering Remediation, Gillian Wilton

Electronic Thesis and Dissertation Repository

Per- and polyfluoroalkyl substances (PFAS) are a group of anthropogenic contaminants that are growing increasing concern due to their associated negative health affects. The properties of PFAS result in their persistence and stability which present challenges for remediation. Activated carbon is currently the most widely used method for PFAS treatment since carbon microparticle injection can be used for in-situ treatment; however, this method does not result in PFAS destruction. Thermal treatment is a promising post-treatment method that can be used with activated carbon as long as sufficient PFAS-destroying temperatures are achieved (> 900°C). A promising in-situ thermal treatment technology is …

Multi-Device Data Analysis For Fault Localization In Electrical Distribution Grids, Jacob D L Hunte

Electronic Thesis and Dissertation Repository

The work presented in this dissertation represents work which addresses some of the main challenges of fault localization methods in electrical distribution grids. The methods developed largely assume access to sophisticated data sources that may not be available and that any data sets recorded by devices are synchronized. These issues have created a barrier to the adoption of many solutions by industry. The goal of the research presented in this dissertation is to address these challenges through the development of three elements. These elements are a synchronization protocol, a fault localization technique, and a sensor placement algorithm.

The synchronization protocol …

Hydrogen-Rich Syngas Derived From Smouldering Biomass And Hydrocarbon Wastes, Joshua K. Brown

Electronic Thesis and Dissertation Repository

In the face of climate change, the world is looking to new fuel sources to meet the surging global energy demand. Hydrogen has been proposed as a promising energy vector being both a net-zero carbon emitter and having one of the highest gravimetric energy densities of known fuels. Production of hydrogen, however, is difficult with many of the technologies which exist today failing to be economically feasible or environmentally sustainable. Smouldering has recently been developed as a cost effective and energy efficient technology for destruction of organic wastes. The unique reaction zones created within a smouldering system have the potential …

Co-Gasification Of Biomass And Plastic Waste In A Bubbling Fluidized Bed Reactor, Islam Elghamrawy

Electronic Thesis and Dissertation Repository

Plastics are versatile, durable, and can be manipulated to match different needs. The COVID-19 pandemic has demonstrated the importance of reducing plastic waste and is believed to be responsible for increasing the generation of plastic waste by 54,000 tons/day which was reported in 2020. Another widely available waste is biomass waste. Agriculture and agroforestry, forest and wood processing, municipal waste, and the food industry are all considered major producers of biowaste. Co-gasification is considered one of the most promising methods of chemical recycling that targets the production of syngas (hydrogen and carbon monoxide) and light hydrocarbon gases. In this study, …

Analysis Of Standing Seam Metal Roofs Subjected To Extreme Wind Loads, Yuchao Xia

Electronic Thesis and Dissertation Repository

Standing seam metal roof (SSMR) systems are widely used in low-rise buildings. This study aims to understand the behavior of SSMR systems, especially the failure mechanisms, under severe wind loads. Full-scale experiments conducted at Insurance Research Lab for Better Homes make it possible to examine the performance of SSMR systems with realistic dimensions and boundary conditions. The induced loads on the clips could be measured directly. The results show that there is a linear relationship between the wind pressure and clip reaction under low wind pressure (less than 500 Pa). It is found that load sharing among clips changes at …

A Dislocation-Based Crystal Plasticity Model For Hexagonal Close-Packed Polycrystals, Omid Sedaghat

Electronic Thesis and Dissertation Repository

Due to their low neutron absorption cross-section and good corrosion properties, zirconium and its alloys have been widely used as the structural material in the core of nuclear reactors. These alloys are exposed to an intensive neutron flux which may lead to dimensional instabilities and the degradation of the mechanical properties of the alloy over the service time of the reactor. The changes in deformation behavior and mechanical properties can be traced back to the formation, evolution, and interaction of the irradiation-induced microstructural defects, e.g., point defect clusters, dislocation loops, and complex dislocation line networks. However, the materials constitutive models …

Wastewater Aeration Process Dynamic Modelling: Combined Mechanistic And Machine Learning Approach, Yuehe Pan

Electronic Thesis and Dissertation Repository

The aeration process is the largest energy consumer in wastewater treatment plants (WWTPs), and the optimization of the process based on computational models can offer significant savings for the plant. Recent theoretical developments have revealed that many of the parameters commonly assumed as constants in aeration modelling, in fact, have a dynamic nature; however, there still lacks a universal way to model these factors in an easy, accurate and timely manner. This work proposed a machine learning-based modelling approach to offer real-time estimations of the oxygen transfer rate, airflow demand, and energy consumption.

Utilizing the field data collected from Adelaide …

The Electrical, Thermal, And Morphological Properties Of Microinjection-Molded Polypropylene Nanocomposites, Renze Jiang

Electronic Thesis and Dissertation Repository

Microinjection molding (µIM) exhibits significantly higher shear rates and faster cooling rates, as compared to conventional injection molding, which affect the characteristics of its final products. The effect of carbon black (CB), carbon nanotubes (CNT), and graphene nanoplatelet (GNP) fillers on the electrical conductivity properties of microinjection-molded polypropylene (PP) nanocomposites was systematically studied. Results showed the electrical conductivity properties of PP/CNT and PP/CB microparts were significantly influenced by mold geometry. PP/CNT/CB hybrid filler microparts demonstrated synergistic increases in electrical conductivity and crystallization temperature with higher CNT loading. Morphological observations indicated significant CB and CNT phase separation. Powder-PP/GNP composites exhibited higher …

Learning Analytics For The Formative Assessment Of New Media Skills, Negar Shabihi

Electronic Thesis and Dissertation Repository

Recent theories of education have shifted learning environments towards student-centred education. Also, the advancement of technology and the need for skilled individuals in different areas have led to the introduction of new media skills. Along with new pedagogies and content, these changes require new forms of assessment. However, assessment as the core of learning has not been modified as much as other educational aspects. Hence, much attention is required to develop assessment methods based on current educational requirements. To address this gap, we have implemented two data-driven systematic literature reviews to recognize the existing state of the field in the …

The Effects Of A Porous Internal Lattice Design On The Articular Contact Mechanics Of Radial Head Hemiarthroplasty Implants, Jessica Benitah

Electronic Thesis and Dissertation Repository

Hemiarthroplasty, where one side of a joint is replaced, is a minimally invasive procedure. It allows for the preservation of native tissue, though a significant ramification is accelerated cartilage wear when articulating with high stiffness materials that do not mimic the mechanical stiffness of the native tissue. An implant that employs a lattice design can significantly lower the stiffness of a solid structure whilst maintaining strength. This study was conducted to investigate the effect of implementing a porous internal lattice structure with a thin outer shell on the articular contact mechanics, using a radial head hemiarthroplasty. It was hypothesized that …