Barrett, The Honors College Thesis/Creative Project Collection
Barrett, The Honors College at Arizona State University proudly showcases the work of undergraduate honors students by sharing this collection exclusively with the ASU community.
Barrett accepts high performing, academically engaged undergraduate students and works with them in collaboration with all of the other academic units at Arizona State University. All Barrett students complete a thesis or creative project which is an opportunity to explore an intellectual interest and produce an original piece of scholarly research. The thesis or creative project is supervised and defended in front of a faculty committee. Students are able to engage with professors who are nationally recognized in their fields and committed to working with honors students. Completing a Barrett thesis or creative project is an opportunity for undergraduate honors students to contribute to the ASU academic community in a meaningful way.
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- Creators: LaBelle, Jeffrey
Description
The Honors Thesis involved the use of vertically-aligned, piezoelectric nanowire sensor arrays configured by Dr. Henry A. Sodano and Dr. Aneesh Koka from the University of Florida, in order to acquire acceleration data. Originally, the project was focused on interfacing and calibrating the barium titanate (BaTio3) sensors to measure wall shear stress, a fluid dynamic characteristic. In order to gain an understanding of these novel piezoelectric sensors, the experiments performed by Sodano and Koka were to be investigated, replicated, and results reproduced. After initial trial phases, signals failed to be consistently measured from the sensors and the project's emphasis was re-defined. The outlined goals were 1) to re-design the initial system used for signal acquisition, 2) test the improved signal acquisition system, 3) successfully measure output signals from the BaTiO3 nanowire sensors, and 4) determine the cause for inconsistent signal measurements from the piezoelectric nanawire sensors. Following a detailed review of the previous experimental procedures and the initial signal acquisition system, an improved acquisition system was designed and its expected behavior was tested and verified. Despite the introduction of the improved acquisition system, voltage outputs were unable to be measured as a function of shaker table acceleration. It was impossible to verify the effect of the improved signal acquisition system on the measured BaTiO3 nanowire sensor output. Based on an analysis of data collected using a commercial 3-axis acceleromoeter, it is hypothesized that the BaTiO3 nanowire sensors were broken after the first experimental trial due to an excessively applied force from an external source (i.e. shaker table, improper handling during experimentation, and/or improper handling during transportation).
ContributorsThomas, Jonah (Author) / Frakes, David (Thesis director) / LaBelle, Jeffrey (Contributor) / Barrett, The Honors College (Contributor)
Created2014-05
Description
Intracranial aneurysms, which form in the blood vessels of the brain, are particularly dangerous because of the importance and fragility of the human brain. When an intracranial aneurysm gets large it poses a significant risk of bursting and causing subarachnoid hemorrhaging (SAH), a possibly fatal condition. One possible treatment involves placing a stent in the vessel to act as a flow diverter. In this study we look at the hemodynamics of two geometries of idealized basilar tip aneurysms, at 2,3, and 4 ml/s pulsatile flow, at three different points in the cardiac cycle. The smaller model had neck and dome diameters of 2.67 mm and 4 mm respectively, while the larger aneurysm had neck and dome diameters of 3 mm and 6 mm respectively. Both diameters and the dome to neck ratio increased in the second model, representing growth over time. Flow was analyzed using stereoscopic particle image velocimetry (PIV) for both geometries in untreated models, as well as after treatment with a high porosity Enterprise stent (Codman and Shurtleff Inc.). Flow in the models was characterized by root mean square velocity in the aneurysm and neck plane, cross neck flow, max aneurysm vorticity, and total aneurysm kinetic energy. It was found that in the smaller aneurysm model (model 1), Enterprise stent treatment reduced all flow parameters substantially. The smallest reduction was in max vorticity, at 42.48%, and the largest in total kinetic energy, at 75.69%. In the larger model (model 2) there was a 52.18% reduction in cross neck flow, but a 167.28% increase in aneurysm vorticity. The other three parameters experienced little change. These results, along with observed velocity vector fields, indicate a noticeable diversion of flow away from the aneurysm in the stent treated model 1. Treatment in model 2 had a small flow diversion effect, but also altered flow in unpredictable ways, in some cases having a detrimental effect on aneurysm hemodynamics. The results of this study indicate that Enterprise stent treatment is only effective in small, relatively undeveloped aneurysm geometries, and waiting until an aneurysm has grown too large can eliminate this treatment option altogether.
ContributorsLindsay, James Bryan (Author) / Frakes, David (Thesis director) / LaBelle, Jeffrey (Committee member) / Nair, Priya (Committee member) / Barrett, The Honors College (Contributor) / School of Humanities, Arts, and Cultural Studies (Contributor)
Created2013-05
Description
The purpose of this thesis was to explore how changes in the geometry of a bifurcating cerebral aneurysm will affect the hemodynamics in idealized models after stent treatment. This thesis explores the use of a computationally modeled Enterprise Vascular Reconstruction Device (Cordis, East Bridgewater, NJ), a high porosity and closed cell design. The models represent idealized cases of saccular aneurysms with dome sizes of either 4mm or 6mm and a dome to neck ratio of either 3:2 or 2:1. Two aneurysm contact angles are studied, one at 45 degrees and the other at 90 degrees. The stent was characterized and deployed with the use of Finite Element Analysis into each model. Computational Fluid Dynamic principles were applied in series of simulations on treated and untreated models. Data was gathered in the neck plane for the average velocity magnitude, root mean squared velocity, average flow vector angle of deflection, and the cross neck flow rate. Within the aneurysm, the average velocity magnitude, root mean squared velocity, and average pressure were calculated. Additionally, the mass flow rate at each outlet was recorded. The results of this study indicate that the Enterprise Stent was most effective in the sharper, 90 degree geometry of Model 3. Additionally, the stent had an adverse effect on the Models 1 and 4, which had the smallest neck sizes. Conclusions are that the Enterprise Stent, as a stand-alone treatment method is only reliable in situations that take advantage of its design.
ContributorsThomas, Kyle Andrew (Author) / Frakes, David (Thesis director) / LaBelle, Jeffrey (Committee member) / Babiker, Haithem (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2013-05