Engineering Commons^™

Application Of Pca To Cardiac Optical Mapping, Louis Woodhams

McKelvey School of Engineering Theses & Dissertations

Structural remodeling of the heart due to pathologies such as hypertension and myocardial infarction leads to the appearance of myofibroblasts, a phenotype largely absent in physiologic myocardium. While myofibroblasts are responsible for wound healing and structural repair of damaged myocardium, they are thought to have deleterious effects on electrical and mechanical properties of the heart. Understanding these effects is critical to developing effective treatments, and has motivated the development of a series of in vitro engineered heart tissues and cardiomyocyte-myofibroblast co-cultures whose mechanical and electrophysiological function can be deduced from video analysis. Electrophysiological properties are evident from changes in intensity …

Characterizing Anisotropy In Fibrous Soft Materials By Mr Elastography Of Slow And Fast Shear Waves, John Larson Schmidt

McKelvey School of Engineering Theses & Dissertations

The general objective of this work was to develop experimental methods based on magnetic resonance elastography (MRE) to characterize fibrous soft materials. Mathematical models of tissue biomechanics capable of predicting injury, such as traumatic brain injury (TBI), are of great interest and potential. However, the accuracy of predictions from such models depends on accuracy of the underlying material parameters. This dissertation describes work toward three aims. First, experimental methods were designed to characterize fibrous materials based on a transversely isotropic material model. Second, these methods are applied to characterize the anisotropic properties of white matter brain tissue ex vivo. Third, …

The Inter-Laminar Shearing Effect On Wrinkle Development In Composite Forming Processes, David Sundquist

McKelvey School of Engineering Theses & Dissertations

Composite materials are becoming prevalent in aerospace industries as the uniqueness of the composite structure allows the composite to be tailored specifically for individual applications. Many fabrication techniques produce defects in composite parts such as wrinkles, fiber waviness, fiber misalignment, and porosity. The driving mechanisms behind these defects occurring during forming processes are not fully understood and, thus, characterization formation of these defects in a uncured state is beneficial to optimize composite processing. This work primarily investigated the influence of how uncured pre-impregnated carbon ply properties affect the wrinkling behavior of a composite laminates. Several factors affecting composite ply forming …

Modeling Acoustic Microfluidic Phenomena In Unconventional Geometries, Andrew Ledbetter

McKelvey School of Engineering Theses & Dissertations

In this work, the performance of a piezoelectrically-actuated ultrasonic droplet generator is analyzed by modeling the harmonic response of a two-dimensional representation of the device cross-section. Observed vibrational and acoustic resonances provide insight into optimal design conditions to achieve efficient, robust droplet ejection. Numerical simulations highlight the importance of the coupled electrical and mechanical behavior of the resonator assembly and show that elastic modes can effectively amplify or dampen acoustic modes within the fluid chamber. Experimentally-validated modeling results guide development of an optimization strategy to further improve device performance. In addition, the standing acoustic field that is the focus of …

Minimum Induced Power For A Helicopter In High-Speed Forward Flight, Junsoo (Sean) Hong

McKelvey School of Engineering Theses & Dissertations

A dynamic inflow model is used to calculate minimum induced power for a helicopter in high-speed forward flight with infinite and finite number of blades. Comparisons between analytical and numerical results are shown and they show good agreement. Different flow conditions (such as with and without reverse flow or inflow feedback) are used to show how each condition affects optimum induced power. Several results confirm the findings of earlier investigations such as a singularity in rotor power in reverse flow and induced power reduction with increase in blade number. Some of the new findings are that greater inflow feedback (due …

Composition-Dependent Mechanisms Of Multiscale Tendon Mechanics, Fei Fang

McKelvey School of Engineering Theses & Dissertations

Tendons serve as an integral part of the musculoskeletal system by transferring loads from muscle to bone and providing joint mobility and stability. From the physiologically-loading perspective, while progress has been made in evaluating mechanical behavior of different types of tendons in tension, further work is needed to relate tendon mechanics to compositional and microstructural properties, particularly under non-tensile loading modalities (i.e., shear, compression). This information is vital to explore mechanisms of how mechanical signals lead to changes in tendon structure and composition to enable these tissues to function properly, including in in vivo multiaxial loading conditions. From the structural …

Fundamental Studies Of Flame Structure Through Laser Plasma Diagnostics, Wendong Wu

McKelvey School of Engineering Theses & Dissertations

Increasing concerns about air pollution and global climate change are drawing attention to the need for efficiency improvements and emission reductions for combustion processes, which account for more than 85% of energy production in United States. Combustion efficiency and emissions are affected by the mixing and reacting of fuel and oxidizer. Understanding such behavior plays a critical role in flame structure studies and combustion optimization. However, experimentally obtaining mixture fraction, which is a widely used quantity to describe the mixing behavior, has proven to be a challenge, especially for heavier hydrocarbon fuels or fuel rich flames. Moreover, measuring flame temperature …

Computational Fluid Dynamics Modeling And Simulations Of Fast Fluidized Bed And Moving Bed Reactors For Chemical Looping Combustion, Mengqiao Yang

McKelvey School of Engineering Theses & Dissertations

Chemical-looping combustion (CLC) is a next generation carbon capture technology with high efficiency and low cost. To assess the potential of this technology for industrial scale power plants, thousands of laboratory scale and many pilot-scale plants have been designed and tested. In recent years, to obtain a thorough understanding of the hydrodynamic behavior inside the reactors and chemical looping combustion process, high-fidelity numerical simulation using Computational Fluid Dynamics(CFD) have been performed. However, CFD simulations in the literature have been limited reported compared to the laboratory scale experiments.

In this thesis, cold flow simulations of a CLC fuel reactor are performed …

Numerical Simulation Of Enhancement In Co2 Sequestration With Various Water Production Schemes Under Multiple Well Scenarios, Li Chen

McKelvey School of Engineering Theses & Dissertations

CO₂ geological sequestration simultaneously combined with water production from deep saline aquifers can effectively address the challenge faced by the modern energy systems for reducing the CO₂ emissions and water intensity while providing reliable, affordable, and secure energy. However, little attention has been paid to date in the literature on determining the best CO₂ injection strategy for achieving both the optimal water production and the optimal CO₂ space storage capacity while maintaining operational safety. This research first establishes three injection-extraction scenarios based on the typical geological parameters of the Junggar Basin in China to analyze the …

Cfd Simulations Of Chemical Looping Combustion In A Packed Bed And A Bubbling Bed Fuel Reactor, Guanglei Ma

McKelvey School of Engineering Theses & Dissertations

Chemical-looping combustion (CLC) is a next generation combustion technology that has shown great promise in addressing the need for high-efficiency low-cost carbon capture from fossil fueled power plants to address the rising carbon emissions. Although there have been a number of experimental studies on CLC in recent years, CFD simulations have been limited in the literature on CLC. The development and confidence in high-fidelity simulations of the CLC process is a necessary step towards facilitating the transition from laboratory-scale experiments to deployment of this technology on an industrial scale. In this research, first the CFD simulations of a CLC packed …

Numerical Simulation Of Flows Past A Circular And A Square Cylinder At High Reynolds Number, And A Curved Plate In Transitional Flow, Ling Zhang

McKelvey School of Engineering Theses & Dissertations

Increasing the prediction accuracy and computational efficiency of turbulence models at high Reynolds number remains a challenging problem in Computational Fluid Dynamics (CFD). In this paper, several turbulence models are applied for numerical simulation of flow past a circular and a square cylinder at high Reynolds number. Wray-Agarwal (WA) turbulence model is a recently developed one-equation turbulence model derived from k-w closure. Comparisons are made among computational results from WA model, Spalart-Allmaras (SA) model, the shear stress transport SST k-w model and the standard Wilcox k-w model. For circular cylinder, the computations are performed for Reynolds numbers and and simulation …

Particle Enrichment In Longitudinal Standing Bulk Acoustic Wave Microfluidics, Mingyang Cui

McKelvey School of Engineering Theses & Dissertations

Separation, isolation, and enrichment of targeted nano- and microparticles are critical to a variety of biomedical applications from clinical research (development of therapeutics and diagnostics) to fundamental investigations that require concentration of specific cells from culture, separation of target species from heterogenous mixtures, or controlled perturbation of cells and microorganisms to determine their response to stimuli. Numerous techniques are available for bench-scale and medical settings; however, these traditional approaches are often labor intensive, time-consuming, costly, and/or require modification of the target. Efficiency and specificity are also lacking. Recently, techniques that exploit the similar scales of microfluidic technologies and the intrinsic …