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Articles 1 - 30 of 69
Full-Text Articles in Engineering
Application Of High-Deflection Strain Gauges To Characterize Spinal-Motion Phenotypes Among Patients With Clbp, Spencer Alan Baker
Application Of High-Deflection Strain Gauges To Characterize Spinal-Motion Phenotypes Among Patients With Clbp, Spencer Alan Baker
Theses and Dissertations
Chronic low back pain (CLBP) is a nonspecific and persistent ailment that entails many physiological, psychological, social, and economic consequences for individuals and societies. Although there is a plethora of treatments available to treat CLBP, each treatment has varying efficacy for different patients, and it is currently unknown how to best link patients to their ideal treatment. However, it is known that biopsychosocial influences associated with CLBP affect the way that we move. It has been hypothesized that identifying phenotypes of spinal motion could facilitate an objective and repeatable method of determining the optimal treatment for each patient. The objective …
Time-Dependent Strain-Resistance Relationships In Silicone Nanocomposite Sensors, Alex Mikal Wonnacott
Time-Dependent Strain-Resistance Relationships In Silicone Nanocomposite Sensors, Alex Mikal Wonnacott
Theses and Dissertations
Flexible high-deflection strain gauges have been demonstrated as cost-effective and accessible sensors for capturing human biomechanical deformations. However, the interpretation of these sensors is notably more complex compared to conventional strain gauges, partially owing to the viscoelastic nature of the strain gauges. On top of the non-linear viscoelastic behavior, dynamic resistance response is even more difficult to capture due to spikes in resistance during strain changes. This research examines the relationships between stress, strain, and resistance in nanocomposite sensors during dynamic strain situations. Under the assumption that both macroscopic stress and resistance are governed by microscopic stress concentrations at the …
A Globalized Optimization Schema For Automated Fiber Placement Processing Parameters, Matthew John Godbold
A Globalized Optimization Schema For Automated Fiber Placement Processing Parameters, Matthew John Godbold
Theses and Dissertations
Automated Fiber Placement is an advanced manufacturing technique for industrial-scale composite structures. Advanced robotics coupled with composite manufacturing results in faster and more consistent results than previously obtained through hand layup. The complexity and interconnectedness of the automated fiber placement process provides a difficult challenge for traditional modeling techniques. Modeling within automated fiber placement currently utilizes physics-based modeling to inform the translation of a design to a manufacturing plan. The intricacy of the automated fiber placement process dictates that attempts at modeling or optimizing these processes are often limited in their scope. Physics-based modeling for manufacturing typically involves numerous interacting …
Numerical Evaluation Of Forces Affecting Particle Motion In Time-Invariant Pressurized Jet Flow, Donald E. Peterson
Numerical Evaluation Of Forces Affecting Particle Motion In Time-Invariant Pressurized Jet Flow, Donald E. Peterson
Theses and Dissertations
This work evaluates the relative significance of forces determining the motion of a pulverized coal particle under conditions representative of a pressurized oxy-coal combustor. The gravity force and surface forces of drag, fluid stress, added mass, and Basset history are discussed and appropriate forms of these force equations are chosen, with a consideration of spherical and non-spherical drag and the Basset history kernel. Studies from the literature that emphasize specific forces are used to validate the implementation of the force equations and correlations. Modeling is based on time-averaged, one-dimensional motion of a single non-reacting particle along the centerline of a …
Comprehensive Process Planning Optimization Framework For Automated Fiber Placement, Alex Ryan Brasington
Comprehensive Process Planning Optimization Framework For Automated Fiber Placement, Alex Ryan Brasington
Theses and Dissertations
Advanced composite materials came about in 1966 and have since been widely used due to the possibility of superior structural performance while also achieving weight reductions. Such opportunities have led to composite materials being used to fabricate complex components, often in the aerospace sector. Most components, especially in aviation, are on a large scale and are outside the capabilities of traditional composite manufacturing techniques. Traditional manufacturing methods are also labor intensive, time consuming, have a high level of material scrap, and are prone to human error. This has led to the need for innovative manufacturing solutions to withstand the ever-increasing …
Closed Form Implicitly Integrated Models For Computationally Efficient Simulation Of Power Electronics, Andrew Wunderlich
Closed Form Implicitly Integrated Models For Computationally Efficient Simulation Of Power Electronics, Andrew Wunderlich
Theses and Dissertations
This work describes novel closed-form, implicitly integrated (CF-implicit) models of switched-mode power converters which feature implicit integration but require no iterative numerical solving algorithm for evaluation because they are explicitly solved prior to model execution. The derived models capture the large-signal dynamic behavior of the power converters, so their use and accuracy are not limited to any one set of operating conditions. These models can be implemented in any computational environment, including directly on an existing embedded controller as a digital twin. Since no iterative solver is required, the models are highly computationally efficient and have a very predictable worst-case …
Parametric Models Of Maize Stalk Morphology, Michael Alan Ottesen
Parametric Models Of Maize Stalk Morphology, Michael Alan Ottesen
Theses and Dissertations
As the most produced grain crop world-wide, 5% of corn is lost due to stalk lodging (above-ground structural failure of the stalk near the roots). Current modeling methods lack the ability to manipulate the stalk architecture. In contrast, parameterized models enable advanced analyses such as sensitivity and optimization studies. This thesis advances previous work on a parameterized cross-sectional model of maize stalk morphology and investigates the validity of a parameterized three-dimensional model. The parameterized cross-sectional model is based upon previous work that approximated the cross-section of maize stalks using an ellipse plus principal components. Validation of the cross-sectional model was …
Modeling The Effects Of Parameter Changes On Heating And Pressure At The Weld Interface And Joint Strength In Friction Bit Joining, Adam Hartly Wagner
Modeling The Effects Of Parameter Changes On Heating And Pressure At The Weld Interface And Joint Strength In Friction Bit Joining, Adam Hartly Wagner
Theses and Dissertations
Joining of dissimilar metals is a process that is of interest in many fields, especially the automotive industry where lightweighting of the body structure is important. However, creating strong joints between dissimilar metals can be challenging. Friction bit joining (FBJ) is a solid-state method that uses a consumable bit to create a strong joint between dissimilar metals such as aluminum and steel. The purpose of this research is to gain understanding of how adjusting FBJ parameters affects the heating and pressure at the weld interface using a modeling approach, in order to better understand the bonding process. The questions guiding …
Development Of A Multi-Scale Mechano-Electrochemical Battery Model, Drew J. Pereira
Development Of A Multi-Scale Mechano-Electrochemical Battery Model, Drew J. Pereira
Theses and Dissertations
As the automotive industry moves towards large format electric vehicles, such as trucks and SUVs, the need for highly efficient, energy-dense electrodes rapidly increases. Several promising active materials have been studied and proposed, however, many of these materials undergo significant volume change upon lithiation and de-lithiation. Cell and pack designers struggle to understand and predict how active material volume change at the particle scale will affect mechano-electrochemical behavior on the electrode, cell, and pack scales. Additionally, many of these active materials suffer in their cycle life due to a mechanically-driven degradation of the electrode matrix. Therefore, the focus of this …
Vascular Endothelial Dysfunction And Effects On Arterial Wall Microstructure, Jeffrey Thomas Rodgers
Vascular Endothelial Dysfunction And Effects On Arterial Wall Microstructure, Jeffrey Thomas Rodgers
Theses and Dissertations
Vascular endothelial cell dysfunction (ECD) is a disease characterized by the inability of the vascular endothelial cells to transmit signaling molecules, namely nitric oxide (NO), in response to changes in blood flow rate. This disease is shown to be incident in the onset of more severe vascular disease such as hypertension, atherosclerosis, and heart failure. Long-term ECD is shown to cause long-term remodeling such as decreased flow-mediated dilation, increased pulse-wave velocity, intimal-medial thickening, and increased wall stiffness due to collagen deposition. We used second harmonic generation (SHG) microscopy to analyze this change in the collagen microstructure of the arterial extracellular …
Coal Pyrolysis Models For Use In Massively Parallel Oxyfuel-Fired Boiler Simulations, Andrew Perry Richards
Coal Pyrolysis Models For Use In Massively Parallel Oxyfuel-Fired Boiler Simulations, Andrew Perry Richards
Theses and Dissertations
Accurately modeling key aspects of coal combustion allows for the virtual testing and application of new technologies and processes without the need for investments in lab- and pilot-scale facilities, since such facilities may only be used for a few small tests. However, modeling of subprocesses must not only be accurate but computationally efficient. Modeling of coal devolatilization reactions and processes are one of the important parts of large-scale simulations of coal combustion systems. The work presented here details efforts to improve the modeling of coal devolatilization processes in massively-parallel simulations of coal combustors, including: (1) devolatilization rate/yield models, (2) modeling …
Development Of A Hurricane Recovery Function And Resilience Model For Single-Family Residential Homes, Uriel Robert Donald Clark
Development Of A Hurricane Recovery Function And Resilience Model For Single-Family Residential Homes, Uriel Robert Donald Clark
Theses and Dissertations
The resilience of communities, infrastructure, and the environment in the face of hurricanes has increasingly become of public interest in the wake of recent natural disasters and environmental activism. Previous methodologies have attempted to quantify resilience for various structures and scenarios. Many studies have primarily investigated the robustness of critical infrastructure (e.g., bridges, emergency facilities, and water systems) which are essential to the function of a community. However, few studies have applied this approach to individual residential buildings. Therefore, this research aimed to adapt the most recent recovery functions developed for residential homes by considering measurable factors that are known …
Computational Modeling Of Radiation Damage In A Multi-Phase Ceramic Waste Form Using Moose, Zeyu Chen
Computational Modeling Of Radiation Damage In A Multi-Phase Ceramic Waste Form Using Moose, Zeyu Chen
Theses and Dissertations
Ceramic waste forms have been proposed to replace the traditional glassy waste forms for long term stabilization of radionuclides. These waste forms are constantly exposed to self-irradiation emitted from the constituent radionuclides causing their material properties to change accordingly. It has been known that the radiation damage in waste forms is dominated by alpha particles emitted from transuranic (TRU) radionuclides. Since alpha particles usually have a range of 10~20 μm in such waste forms, some fraction of any non-transuranic containing phases (for a multiphase waste form) will be undamaged (or less damaged) if containing large enough grain sizes. Modeling and …
Characterization And Optimization Of An Image Charge Detector For The Measurement Of Martian Dust, Jace Rozsa
Characterization And Optimization Of An Image Charge Detector For The Measurement Of Martian Dust, Jace Rozsa
Theses and Dissertations
Image charge detector (ICD) technology has existed for decades. However, not until recently has an ICD been proposed for use in space exploration, specifically for studying the characteristics of the dust on Mars. Characterizing the dust on Mars is crucial for designing equipment to aid manned missions. It also improves our understanding of Mars' climate and weather systems. An ICD utilizing printed circuit board (PCB) electrodes, coupled with a custom differential amplifier, is best suited for this type of measurement because of its light weight, simplicity, and noise performance. The noise floor of our particular amplifier is measured to be …
Molecular Modeling Of Tethered Polyelectrolytes For Novel Biomedical Applications, Merina Jahan
Molecular Modeling Of Tethered Polyelectrolytes For Novel Biomedical Applications, Merina Jahan
Theses and Dissertations
Current research trends throughout the world focus on designing intelligent materi- als and systems for diverse applications in all courses of life. Biomaterials research encompasses a major part in this revolution due to the increased effort in fulfilling unmet medical needs to treat complex physiological and neurodegenerative disorders. Polymers play inevitable roles in these research endeavors for their ubiquitous pres- ence in biological systems. Therefore, it is crucial to understand how the polymeric molecules interact within diverse biological environments, to efficiently engineer them for various drug delivery and biosensing systems. The use of experimental design and selection of different polymers …
Modeling Neutron Interaction Inside A 2d Reactor Using Monte Carlo Method, A. S. M. Fakhrul Islam
Modeling Neutron Interaction Inside A 2d Reactor Using Monte Carlo Method, A. S. M. Fakhrul Islam
Theses and Dissertations
Scientists and engineers have been working for many years to develop accurate approaches to analyzing nuclear power reactors using computer codes that closely model the behavior of neutrons in a reactor core. The Monte Carlo simulation method is capable of treating complex geometries with a high level of resolution and fidelity to model neutron interactions inside a reactor core. With the requirement of accurate modeling in reactor physics and dynamics and great innovation of computer technology, Monte Carlo method is becoming an ever more powerful tool and receiving rising attention. In this study, Monte Carlo method is used to model …
Comparison Of Heat Generation Models In Finite Element Analysis Of Friction Welding, Richard Verile Livingston
Comparison Of Heat Generation Models In Finite Element Analysis Of Friction Welding, Richard Verile Livingston
Theses and Dissertations
Finite element models of friction welding can be used to estimate internal conditions of welds which are useful for weld analysis and developing experimental welding procedures. Many modeling techniques are used to accomplish these goals, each with relative strengths and weaknesses. A comparative analysis of friction welding models using different heat generation methods is presented. The three different heat generation methods examined were viscoplastic friction, constant steady-state generation, and experimentally measured power data. The models were compared against each other using three output measurements: temperature, axial force, and upset. The friction model predicted temperatures within 40 degrees C. Temperature accuracy …
Three-Dimensional Collagen Tubes For In Vitro Modeling, Rebecca Jones
Three-Dimensional Collagen Tubes For In Vitro Modeling, Rebecca Jones
Theses and Dissertations
Collagen type I represents a novel material for three-dimensional in vitro models. While two-dimensional models are typically inadequate for recreating the complex processes of the body, collagen provides a three-dimensional basis with a variety of applications, including remodeling of vascular cells under tension and vascular stenosis. Smooth muscle cells reorganize and reconstruct their environment differently under conditions of tensions, such as with sutures, or under conditions without applied external tension. Vascular stenosis, the abnormal narrowing of blood vessels, arises from defective developmental processes or atherosclerosis-related adult pathologies. Stenosis triggers a series of adaptive cellular responses that induces adverse remodeling, which …
The Restoration Of The Nile River And Its Delta, Egypt. Numerical Modeling, Basim Mohammed Naseef Al-Zaidi
The Restoration Of The Nile River And Its Delta, Egypt. Numerical Modeling, Basim Mohammed Naseef Al-Zaidi
Theses and Dissertations
The construction of the High Aswan Dam significantly reduced the flood flows and the sediment supply to the Egyptian portion of the Nile River. Consequences of this changes in river hydrology are diffuse channel bed erosion in the upstream part of the river, in- channel sedimentation in the downstream part of the system, delta recession, habitat deterioration, wetlands loss, water pollution, and environmental problems. The feasibility of a Nile River-Delta restoration project with controlled flow releases and sediment augmentations at Aswan is here investigated with the aid of site-specific one-dimensional morphodynamic models. The water source for the restoration project, based …
Smart Technologies For Oil Production With Rod Pumping, Brigham Wheeler Hansen
Smart Technologies For Oil Production With Rod Pumping, Brigham Wheeler Hansen
Theses and Dissertations
This work enables accelerated fluid recovery in oil and gas reservoirs by automatically controlling fluid height and bottomhole pressure in wells. Several literature studies show significant increase in recovered oil by determining a target bottomhole pressure but rarely consider how to control to that value. This work enables those benefits by maintaining bottomhole pressure or fluid height. Moving Horizon Estimation (MHE) determines uncertain well parameters using only common surface measurements. A Model Predictive Controller (MPC) adjusts the stroking speed of a sucker rod pump to maintain fluid height. Pump boundary conditions are simulated with Mathematical Programs with Complementarity Constraints (MPCCs) …
Assured Android Execution Environments, Brandon P. Froberg
Assured Android Execution Environments, Brandon P. Froberg
Theses and Dissertations
Current cybersecurity best practices, techniques, tactics and procedures are insufficient to ensure the protection of Android systems. Software tools leveraging formal methods use mathematical means to assure both a design and implementation for a system and these methods can be used to provide security assurances. The goal of this research is to determine methods of assuring isolation when executing Android software in a contained environment. Specifically, this research demonstrates security properties relevant to Android software containers can be formally captured and validated, and that an implementation can be formally verified to satisfy a corresponding specification. A three-stage methodology called "The …
Development Of Novel Models To Study Deep Brain Effects Of Cortical Transcranial Magnetic Stimulation, Farheen Syeda
Development Of Novel Models To Study Deep Brain Effects Of Cortical Transcranial Magnetic Stimulation, Farheen Syeda
Theses and Dissertations
Neurological disorders require varying types and degrees of treatments depending on the symptoms and underlying causes of the disease. Patients suffering from medication-refractory symptoms often undergo further treatment in the form of brain stimulation, e.g. electroconvulsive therapy (ECT), transcranial direct current stimulation (tDCS), deep brain stimulation (DBS), or transcranial magnetic stimulation (TMS). These treatments are popular and have been shown to relieve various symptoms for patients with neurological conditions. However, the underlying effects of the stimulation, and subsequently the causes of symptom-relief, are not very well understood. In particular, TMS is a non-invasive brain stimulation therapy which uses time-varying magnetic …
Modeling Of Tow Wrinkling In Automated Fiber Placement Based On Geometrical Considerations, Roudy Wehbe
Modeling Of Tow Wrinkling In Automated Fiber Placement Based On Geometrical Considerations, Roudy Wehbe
Theses and Dissertations
Automated manufacturing of fiber reinforced composite structures via numerically controlled hardware yields parts with increased accuracy and repeatability as compared to hand-layup parts. Automated fiber placement (AFP) is one such process in which structures or parts are built by adding bands of prescribed number of tows or slit-tape with prescribed width using robotic machine heads over 3D surfaces following prescribed paths. Despite the improved accuracy, different types of defects or manufacturing features arise during fabrication. These defects can be due to geometrical features, materials, and process planning parameters and are detected in the form of wrinkling, tow twist, tow folding, …
Sensitivity Analysis Of Geometry Changes In The Simulation Of Basilar Aneurysms, Paul Eserkaln
Sensitivity Analysis Of Geometry Changes In The Simulation Of Basilar Aneurysms, Paul Eserkaln
Theses and Dissertations
Computer simulation is a useful tool in the research and treatment of basilar aneurysms. Current technology allows researchers to create 3D models from cerebral vasculature in-vivo, allowing for the investigation of surgical options with minimal risk to the patient. The method used to construct these models overlooks smaller lateral arterial branches which are difficult to discern due to resolution limits of the imaging process. These lateral branches have minimal impact on the overall blood flow through the basilar artery, but they play a significant role in the health of the patient, so it is important to ensure sufficient blood will …
Modeling And Loss Analysis Of Wide Bandgap Power Semiconductor Devices, Kang Peng
Modeling And Loss Analysis Of Wide Bandgap Power Semiconductor Devices, Kang Peng
Theses and Dissertations
In recent times, the development of high power density and high efficiency power converters has become critical in power electronics applications like electric vehicles, aircrafts, electric ships and so on. High-switching-frequency and high-temperature operation are required to achieve this target. However, these requirements are exceeding the theoretical material-related limits of silicon (Si) based devices. The emerging wide bandgap power semiconductor technology is a promising solution to meet these requirements. Silicon Carbide (SiC) and Gallium Nitride (GaN) are the most promising among all wide bandgap semiconductor materials. SiC and GaN have almost a three times larger bandgap (about 3eV), compared with …
Modeling Human-Structure Interaction Using A Controller System, Albert Ricardo Ortiz Lasprilla
Modeling Human-Structure Interaction Using A Controller System, Albert Ricardo Ortiz Lasprilla
Theses and Dissertations
The effects of human loads on structures are difficult to predict because they depend on the type of activity people are performing. However, models for typical activities such as standing, sitting and jumping have been proposed in the literature. Traditional models represent the human body as a system of lumped masses, dampers and springs arranged in a system with multiple degrees of freedom. Arguably, these models might not fully represent the human body because lumped masses, dampers and springs cannot add energy to the overall system. Furthermore, people could react differently to different levels of excitation and other environmental conditions. …
Simple Models For Estimating The Rotational Stiffness Of Steel Column-To-Footing Connections, Joshua Edwin Tryon
Simple Models For Estimating The Rotational Stiffness Of Steel Column-To-Footing Connections, Joshua Edwin Tryon
Theses and Dissertations
Despite the crucial role they play in transferring loads from the superstructure to the foundation, steel column-to-footing connections have received little attention in research. Though shallow embedded connections are typically characterized as pinned, studies have shown that they exhibit significant rotational stiffness. The objective of this thesis is to quantify the rotational stiffness of such connections. A method named the continuum model is developed by which the rotational stiffness of embedded connections may be calculated. Outputs from this model are compared with experimental data on steel connections embedded in concrete. The continuum model is shown to be capable of reasonably …
Automated Image Analysis And Spatial Computational Modeling Of Nf-Kb In Cerebrovascular Endothelial Cells, Kasey Catalfomo
Automated Image Analysis And Spatial Computational Modeling Of Nf-Kb In Cerebrovascular Endothelial Cells, Kasey Catalfomo
Theses and Dissertations
Cerebrovascular endothelial cells play a key part in the inflammatory response of the blood-brain barrier in pathological conditions such as Alzheimer’s disease. Specifically, the NF-κB signaling pathway plays a central role. Better understanding of the factors in inflammatory disease progression can lead to more effective treatments for such devastating illnesses like Alzheimer’s, asthma, arthritis, cancer, diabetes and many more inflammatory diseases. The proposed approach analyzes spatial NF-κB distribution contained in multispectral stacked micrograph images of cerebrovascular endothelial cells indexed based on dose of the activating protein and the length of activation. Image analysis code identifies the location of nuclear boundaries …
Modeling Embankment Breach Due To Overtopping, Ali Asghari Tabrizi
Modeling Embankment Breach Due To Overtopping, Ali Asghari Tabrizi
Theses and Dissertations
Despite numerous embankment failures around the world, in-depth assessments as well as reliable, comprehensive sets of data of such failures are limited. Detailed understanding of the earthen embankment failure process and the dominant parameters affecting the failure are needed to predict and model the breach process precisely. Therefore, a series of laboratory experiments on embankment (i.e., dam and levee) overtopping as well as erodibility measurements using the Submerged Jet test are conducted. Also, to study the influence of different model parameters (e.g., turbulence model, bedload formula), one of the dam embankment experiments is simulated. The main goal of this research …
Intercode Advanced Fuels And Cladding Comparison Using Bison, Frapcon, And Femaxi Fuel Performance Codes, Aaren Rice
Intercode Advanced Fuels And Cladding Comparison Using Bison, Frapcon, And Femaxi Fuel Performance Codes, Aaren Rice
Theses and Dissertations
The high density uranium-based fuels are regaining popularity as the current fleet of LWR’s are showing interest in uprating plants to increase accident tolerance and performance. Fuels such as U3Si2, UN, and UC all contain a higher uranium loading and thermal conductivity than that of UO2 making them attractive in combination with an advanced cladding type such as the ceramic SiC cladding. In addition to adding more mass uranium to the core without surpassing current enrichment limits, these advanced fuels and claddings are designed with increased accident tolerance performance in a LOCA type scenario in mind. One of the possible …