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- All Subjects: engineering
- Creators: Engineering Programs
Description
Magnetic Resonance Imaging using spiral trajectories has many advantages in speed, efficiency in data-acquistion and robustness to motion and flow related artifacts. The increase in sampling speed, however, requires high performance of the gradient system. Hardware inaccuracies from system delays and eddy currents can cause spatial and temporal distortions in the encoding gradient waveforms. This causes sampling discrepancies between the actual and the ideal k-space trajectory. Reconstruction assuming an ideal trajectory can result in shading and blurring artifacts in spiral images. Current methods to estimate such hardware errors require many modifications to the pulse sequence, phantom measurements or specialized hardware. This work presents a new method to estimate time-varying system delays for spiral-based trajectories. It requires a minor modification of a conventional stack-of-spirals sequence and analyzes data collected on three orthogonal cylinders. The method is fast, robust to off-resonance effects, requires no phantom measurements or specialized hardware and estimate variable system delays for the three gradient channels over the data-sampling period. The initial results are presented for acquired phantom and in-vivo data, which show a substantial reduction in the artifacts and improvement in the image quality.
ContributorsBhavsar, Payal (Author) / Pipe, James G (Thesis advisor) / Frakes, David (Committee member) / Kodibagkar, Vikram (Committee member) / Arizona State University (Publisher)
Created2013
Description
The aim of this study was to investigate the microstructural sensitivity of the statistical distribution and diffusion kurtosis (DKI) models of non-monoexponential signal attenuation in the brain using diffusion-weighted MRI (DWI). We first developed a simulation of 2-D water diffusion inside simulated tissue consisting of semi-permeable cells and a variable cell size. We simulated a DWI acquisition using a pulsed gradient spin echo (PGSE) pulse sequence, and fitted the models to the simulated DWI signals using b-values up to 2500 s/mm2. For comparison, we calculated the apparent diffusion coefficient (ADC) of the monoexponential model (b-value = 1000 s/mm2). In separate experiments, we varied the cell size (5-10-15 μ), cell volume fraction (0.50-0.65-0.80), and membrane permeability (0.001-0.01-0.1 mm/s) to study how the fitted parameters tracked simulated microstructural changes. The ADC was sensitive to all the simulated microstructural changes except the decrease in membrane permeability. The σstat of the statistical distribution model increased exclusively with a decrease in cell volume fraction. The Kapp of the DKI model increased exclusively with decreased cell size and decreased with increasing membrane permeability. These results suggest that the non-monoexponential models have different, specific microstructural sensitivity, and a combination of the models may give insights into the microstructural underpinning of tissue pathology. Faster PROPELLER DWI acquisitions, such as Turboprop and X-prop, remain subject to phase errors inherent to a gradient echo readout, which ultimately limits the applied turbo factor and thus scan time reductions. This study introduces a new phase correction to Turboprop, called Turboprop+. This technique employs calibration blades, which generate 2-D phase error maps and are rotated in accordance with the data blades, to correct phase errors arising from off-resonance and system imperfections. The results demonstrate that with a small increase in scan time for collecting calibration blades, Turboprop+ had a superior immunity to the off-resonance related artifacts when compared to standard Turboprop and recently proposed X-prop with the high turbo factor (turbo factor = 7). Thus, low specific absorption rate (SAR) and short scan time can be achieved in Turboprop+ using a high turbo factor, while off-resonance related artifacts are minimized.
ContributorsLee, Chu-Yu (Author) / Debbins, Josef P (Thesis advisor) / Bennett, Kevin M (Thesis advisor) / Karam, Lina (Committee member) / Pipe, James G (Committee member) / Arizona State University (Publisher)
Created2012
Description
This thesis presents a kit of materials intended to present students with a glimpse of what engineering entails by guiding them through building engineering projects similar to what is in the real world. The objective of this project is to pique the interest of children by introducing them to lesser known engineering related topics, and increasing their literacy of terms and methods engineers use to solve problems. The effectiveness of the kit’s content and teaching methods was tested in a classroom of 6th graders and was measured using the responses from surveys handed out. I found that kit did in fact positively lead to a change in the way the students perceived engineering, and it taught students about new engineering related topics. Students were capable of completing difficult tasks of wiring and coding successfully through the use of detailed instruction. However, the instructions were seen in two opposing views of either being too overwhelming or more guidance was necessary.
ContributorsQuezada, Hebellyn Arleth (Author) / Aukes, Daniel (Thesis director) / Kellam, Nadia (Committee member) / Engineering Programs (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
The relationship between video games and education is something that has been studied extensively in academia. Based upon these studies a new concept was created, gamification. Gamification is the next step in video game research to analyze why video games enhance learning. The interest and research into this concept have developed so much so that it has become its own topic area for research. This study is looking to analyze the effect that gamification has on not only learning, but also self-efficacy. Through a choose your own adventure game, the knowledge and self-efficacy of participants will be examined to observe the differences when learning difficult engineering concepts with and without gamification. It is expected that participants that experienced training through gamification will demonstrate deeper learning and higher self-efficacy than trained through a video. Furthermore, it is anticipated that some video trained participants’ self-efficacy will increase; however, their comprehension will be less than participants trained through gamification. The results of this study can help promote the interest in researching gamification and education, while influencing educators to corporate gamification elements when designing their courses. Moreover, this study continued through adaptation and integration into a statics forces class, investigated if the same results can be found within a classroom setting.
ContributorsKanechika, Amber (Author) / Craig, Scotty (Thesis director) / Roscoe, Rod (Committee member) / Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
The purpose of this study is to spark a discussion for engineers and their firms to consider the impact of border barriers on wildlife. The focus of this study is to consider if or how engineers make those considerations, such as through design modifications. Barriers block wildlife migration patterns, disabling them from life-sustaining resources. This is particularly important due to an increasing trend in habitat loss, urban development, and climate change. During literature analysis of border barrier impacts, and outreaching to relevant organizations and individuals, there was little to no public documentation or discussion from the engineering community found. Discussion that was found is included in this study, but the lack of connection between conservation and engineering professionals is eminently profound. Therefore, the analysis of studying engineering design considerations additionally studied the relationship between environmental and engineering professionals. Types of research included involves literature analysis of journal articles, reports, project plans for construction, and environmental laws pertinent to wildlife impact.
ContributorsMcMillin, Kaci (Author) / Karwat, Darshan (Thesis director) / Senko, Jesse (Committee member) / Engineering Programs (Contributor) / Environmental and Resource Management (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
This creative project is a children’s book designed to teach young readers about engineering through a fictional story about a group of children creating a robot for their school’s show-and-tell. The story aims to teach engineering principles to children in a lighthearted and entertaining form, narrating notions such as the design process, prototyping, specialty fields, and repurposing. Other principles such as learning patience, compromise and teamwork are also conveyed throughout the plot details. Small life lessons that transcend the realm of engineering are also embodied throughout. The plot of the story is a young girl who goes to visit her grandfather who is a garage tinkerer with a love of spare parts. He tells her about his job as a robotics engineer, and she loves it. She goes and tells her friends who decide they want to make a robot for show-and-tell at school. The grandfather agrees to help them build a robot and thus the group of kids are walked through the engineering design process, learning new things (and specialization) along the way. The story ends by revealing that the whole story was a flashback the main character was having as she is about to start her first day at an engineering firm.
ContributorsReed, Shelby Marie (Author) / Oberle, Eric (Thesis director) / Williams, Wendy (Committee member) / Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
With the ongoing development of simulation technology, classic barriers to social interactions are beginning to be dismantled. One such exchange is encapsulated within education—instructors can use simulations to make difficult topics more manageable and accessible to students. Within simulations that include virtual humans, however, there are important factors to consider. Participants playing in virtual environments will act in a way that is consistent with their real-world behaviors—including their implicit biases. The current study seeks to determine the impact of virtual humans’ skin tone on participants’ behaviors when applying engineering concepts to simulated projects. Within a comparable study focused on a medical training simulation, significantly more errors and delays were made when working for the benefit of dark-skinned patients in a virtual context. In the current study, participants were given a choose-your-own-adventure style game in which they constructed simulated bridges for either a light- ordark-skinned community, and the number of errors and time taken for each decision was tracked. Results are expected to be consistent with previous study, indicating a higher number of errors and less time taken for each decision, although these results may be attenuated by a
lack of time pressure and urgency to the given situations. If these expected results hold, there may be implications for both undergraduate engineering curriculum and real-world engineering endeavors.
lack of time pressure and urgency to the given situations. If these expected results hold, there may be implications for both undergraduate engineering curriculum and real-world engineering endeavors.
ContributorsEldemire, Kate (Author) / Craig, Scotty D. (Thesis director) / Roscoe, Rod D. (Committee member) / Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
All around the automotive industry, the chassis dynamometer exists in a variety of configurations but all function to provide one common goal. The underlying goal is to measure a vehicle’s performance by measuring torque output and taking that measurement to calculate horsepower. This data is crucial in situations of testing development vehicles or for tuning heavily modified vehicles. While the current models in the industry serve their purposes for what they were intended to do, in theory, an additional system can be introduced to the dyno to render the system into an electric generator.
The hardware will consist of electric motors functioning as a generator by reversing the rotation of the motor (regenerative braking). Using the dynamometer with the additional motor system paired with a local battery, the entire system can be run off by their tuning service. When considering the Dynojet and Dynapack dynamometer, it was calculated that an estimated return of 81.5% of electricity used can be generated. Different factors such as how frequent the dyno is used and for how long affect the savings. With a generous estimate of 6 hours dyno run time a day for 250 business days and the cost of electricity being 13.19 cents/kwh the Dynapack came out to $326.45 a year and $1424.52 for the Dynojet. With the return of electricity, the amount saved comes out to $266.18 for the Dynapack and $1161.50 for the Dynojet. This will alleviate electrical costs dramatically in the long term allowing for performance shops to invest their saved money into more tools and equipment.
The hardware will consist of electric motors functioning as a generator by reversing the rotation of the motor (regenerative braking). Using the dynamometer with the additional motor system paired with a local battery, the entire system can be run off by their tuning service. When considering the Dynojet and Dynapack dynamometer, it was calculated that an estimated return of 81.5% of electricity used can be generated. Different factors such as how frequent the dyno is used and for how long affect the savings. With a generous estimate of 6 hours dyno run time a day for 250 business days and the cost of electricity being 13.19 cents/kwh the Dynapack came out to $326.45 a year and $1424.52 for the Dynojet. With the return of electricity, the amount saved comes out to $266.18 for the Dynapack and $1161.50 for the Dynojet. This will alleviate electrical costs dramatically in the long term allowing for performance shops to invest their saved money into more tools and equipment.
ContributorsCrisostomo, Ryan-Xavier Eddie (Author) / Contes, James (Thesis director) / Wishart, Jeffrey (Committee member) / Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
The initial women pioneers in engineering faced many of the same barriers as women engineers today, including stereotypes, unfair treatment in the workplace, restrictions and lack of opportunities, and lack of recognition. Research shows that these barriers are the primary reason why women’s representation within engineering has been low and slow to increase compared to their representation in other fields such as nursing and science. As of 2013, women still only account for 12 percent of all engineers. Yet, despite the barriers and low numbers, women engineers have demonstrated themselves as capable of succeeding just as much, if not more, than their male peers. Some of the ways they have broken the barriers in engineering have been through focusing on proving their merit, finding alternative paths, leveraging government jobs and programs, finding support among other women engineers, fighting for their right to be engineers, and through being satisfied and interested in their work. This thesis analyzes reasons why women have been underrepresented in the field, major achievements from women engineers, and strategies women engineers have adopted to mitigate barriers. The individual profiles of the women discussed in this thesis come from historical research on pioneer women engineers and interviews from modern day women engineers. Their stories help tell the history of how the experiences of women in engineering have changed and remained the same over the past 140 years. The goal of this thesis is to serve as a resource for young women who want to learn more about women in engineering. The history of women engineers is a story worth sharing to everyone because it could inspire young girls to consider engineering as a path for the future and help shift the mindset of members of society to accept and encourage women engineers.
ContributorsDye, Michaela Lynn (Author) / Nystrom, Eric (Thesis director) / Brunhaver, Samantha (Committee member) / Engineering Programs (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
The goal of our research was to develop and validate a method for predicting the mechanical behavior of Additively Manufactured multi-material honeycomb structures. Multiple approaches already exist in the field for modeling the behavior of cellular materials, including the bulk property assumption, homogenization and strut level characterization [1]. With the bulk property approach, the structure is assumed to behave according to what is known about the material in its bulk formulation, without regard to its geometry or scale. With the homogenization technique, the specimen that is being tested is treated as a solid material within the simulation environment even if the physical specimen is not. Then, reduced mechanical properties are assigned to the specimen to account for any voids that exist within the physical specimen. This approach to mechanical behavior prediction in cellular materials is shape dependent. In other words, the same model cannot be used from one specimen to the next if the cell shapes of those lattices differ in any way. When using the strut level characterization approach, a single strut (the connecting member between nodes constituting a cellular material) is isolated and tested. With this approach, there tends to be a significant deviation in the experimental data due to the small size of the isolated struts. Yet it has the advantage of not being shape sensitive, at least in principle. The method that we developed, and chose to test lies within the latter category, and is what we have coined as the Representative Lattice Element (RLE) Method. This method is modeled after the well-established Representative Volume Element (RVE) method [2]. We define the RLE as the smallest unit over which mechanical tests can be conducted that will provide results which are representative of the larger lattice structure. In other words, the theory is that a single member (or beam in this case) of a honeycomb structure can be taken, tests can be conducted on this member to determine the mechanical properties of the representative lattice element and the results will be representative of the mechanical behavior whole structure. To investigate this theory, we designed specimens, conducted various tensile and compression tests, analyzed the recorded data, conducted a micromechanics study, and performed structural simulation work using commercial Finite Element Analysis software.
ContributorsSalti, Ziyad Zuheir (Co-author) / Eppley, Trevor (Co-author) / Bhate, Dhruv (Thesis director) / Song, Kenan (Committee member) / Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05