ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
To help better understand how the football helmet design features effect the brain response during impact, this research develops a validated football helmet model and couples it with a full LS-DYNA human body model developed by the Global Human Body Modeling Consortium (v4.1.1). The human body model is a conglomeration of several validated models of different sections of the body. Of particular interest for this research is the Wayne State University Head Injury Model for modeling the brain. These human body models were validated using a combination of cadaveric and animal studies. In this study, the football helmet was validated by laboratory testing using drop tests on the crown of the helmet. By coupling the two models into one finite element model, the brain response to impact loads caused by helmet design features can be investigated. In the present research, LS-DYNA is used to study a helmet crown impact with a rigid steel plate so as to obtain the strain-rate, strain, and stress experienced in the corpus callosum, midbrain, and brain stem as these anatomical regions are areas of concern with respect to mTBI.
I operated the bench-scale isMBfR system in 7 different conditions to evaluate its nitrate-removal performance. When I supplied H2 with the isMBfR (stages 1 - 6), I observed at least 70% nitrate removal, and almost all of the denitrification occurred in the "MBfR zone." When I stopped the H2 supply in stage 7, the nitrate-removal percentage immediately dropped from 92% (stage 6) to 11% (stage 7). Denitrification raised the pH of the bulk liquid to ~ 9.0 for the first 6 stages, but the high pH did not impair the performance of the denitrifiers. Microbial community analyses indicated that DB were the dominant bacteria in the "MBfR zone," while photosynthetic Cyanobacteria were dominant in the "photo-zone".
I derived stoichiometric relationships among COD, alkalinity, H2, Dissolved Oxygen (DO), and nitrate to model the nitrate removal capacity of the "MBfR zone." The stoichiometric relationships corresponded well to the nitrate-removal capacity for all stages expect stage 3, which was limited by the abundance of Denitrifying Bacteria (DB) so that the H2 supply capacity could not be completely used.
Finally, I analyzed two case studies for the real-world application of the isMBfR to constructed wetlands. Based on the characteristics for the wetlands and the stoichiometric relationships, I designed a feasible operation condition (membrane area and H2 pressure) for each wetland. In both cases, the amount of isMBfR surface area was modest, from 0.022 to 1.2 m2/m3 of wetland volume.