2017 MU theses - Freely available online
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Item Computational study of infrared spectra of silica polymorphs via classical mechanics(University of Missouri--Columbia, 2017) Guo, Jiasen; Hammond, KarlA potential energy model that correctly reflects zeolite framework interactions is the premise for computational studies of the physical and chemical processes occurring inside zeolites, such as catalytic chemical reactions and adsorption. Infrared spectroscopy is a widely-used technique that is sensitive to the accuracy of the potential energy model. This work aims to develop such a potential that reproduces the infrared spectra of zeolites. In the first part of this thesis, the performance of two published potentials is tested in terms of predicting structural and dynamical properties for five silica polymorphs (three siliceous zeolites: siliceous faujasite, sodalite and silicalite; quartz; and cristobalite). Comparison between the silica polymorphs' model-predicted equilibrium angle distributions and infrared spectra shows that the core-shell model [Schroeder and Sauer, J. Phys. Chem. 1996, 100, 11043] predicts a broader Si-O-Si angle distribution and shifts angle-bending infrared modes to lower wavenumbers. The MZHB potential [Sahoo and Nair, J. Comput. Chem. 2015, 36, 1562], on the other hand, predicts angle-bending infrared modes that are consistently shifted to higher wavenumbers. The second part of this thesis presents a new potential via reparameterizing and extending the MZHB potential based on a sensitivity analysis, which investigates the relationships between model parameters and the structural properties of silica polymorphs. Better infrared predictions are achieved by the new potential. The results of the sensitivity analysis indicate that the lattice parameter might be a possible target for the parameterization of atomic partial charges for crystalline materials.Item Semi-automatic exploratory data analytics for actionable discoveries through subgroup mining(University of Missouri--Columbia, 2017) Liu, Danlu; Shyu, Chi-RenPeople are born with the curiosity to see differences between groups. These differences are useful for understanding the root causes of certain discrepancies, such as populations and diseases. However, without prior knowledge of the data, it is extremely challenging to identify which groups differ most, let alone to discover what associations contribute to the differences. The challenges are mainly from the large searching space with complex data structure, as well as the lack of efficient quantitative measurements that are closely related to the meaning the differences. To tackle these issues, we developed a novel exploratory data mining method to identify ranked subgroups that are highly contrasted for further in-depth analyses. The underpinning components of this method include (1) a semi-greedy forward floating selection algorithm to reduce the search space, (2) a deep-exploring approach to aggregate a collection of sizable and creditable candidate feature sets for subgroups identification using in-memory computing techniques, (3) a G-index contrast measurement to guide the exploratory process and to evaluate the patterns of subgroup pairs, and (4) a ranking method to provide mined results from highly contrasted subgroups. Computational experiments were conducted on both synthesized and real data. The algorithm performed adequately in recognizing known subgroups and discovering new and unexpected subgroups. This exploratory data analysis method will provide a new paradigm to select data-driven hypotheses that will produce potentially successful actionable outcomes to tailor to subpopulations of individuals, such as consumers in E-commerce and patients in clinical trials.Item Experimental assessment of advanced thermal imaging for detecting voids in ducts(University of Missouri--Columbia, 2017) Dawson, James; Washer, Glenn A.This research will evaluate the ability of a transient based Infrared Thermography (IRT) technology called the Infrared Ultra Time Domain (IR-UTD) system to detect defects in Post Tensioned (PT) ducts. In recent years, there has been an increasing number of bridges in the National Bridge Inventory (NBI) constructed using PT concrete design. Post Tensioning is a design concept in which steel tendons are placed inside plastic or galvanized steel ducts that are embedded within the concrete itself. If not constructed properly, voids are created during the construction process. These voids allow water and chlorides to ingress into the ducts and cause the steel tendons to corrode. A PT specimen will be cast with embedded defects at known locations and exposed to diurnal heating and cooling cycles. The IR system will collect data while the specimen is fully exposed to the environment. Data will also be collected after an air controlled enclosure is constructed around the specimen to simulate the temperature gradient that the outer wall of a box girder bridge is subjected to. This research shows that in direct sunlight, the IR-UTD processing produced indications from implanted defects of varying sizes inside of a galvanized steel duct. Additionally, the effect from having air control on the inside of the structure didn't significantly affect the results. To obtain a full scope of the abilities of the IRT system, a procedure to properly insulate the specimen to prevent uneven thermal gradients will be necessary. Testing during the summer months where the sun is in the sky for a longer period would also be beneficial.Item Mobile banking : what drives consumer adoption(University of Missouri--Columbia, 2017) Zirk, Elizabeth M.; Frisby, Cynthia M.There's an app for that! Thanks to smartphone penetration, one technological revolution has spawned the creation of countless mobile innovations, including mobile banking which allows users to manage their finances from their mobile device. Knowing what drives the rate of mobile banking adoption can help financial institutions target and convert non-users and improve their overall customer experience. This thesis highlights the relevance of mobile banking through the theoretical framework of Everett Rogers' Diffusion of Innovations and explores potential drivers of mobile banking adoption. Results from the survey reveal the demographic and attitudinal characteristics of mobile banking users who are at least 18 years of age and reside in the United States.Item Effects of expressing emotion and altering loco color in organizational crisis responses(University of Missouri--Columbia, 2017) Won, Jiyoung; Lee, SungkyoungA crisis is inevitable. Any organization needs crisis communication plans and response strategies to protect themselves from reputational damage. This study examines whether employing sadness-expressive words and black-and-white logos in crisis response messages can be an effective strategy that leads to a more positive organizational reputation in the wake of a crisis. A 2 (emotion: presence of sadness vs. absence) x 2 (logo color: standard vs. black-and-white) within-subject factorial experiment was conducted with 188 participants. The experimental stimuli were crisis response messages in the form of Facebook posts from four existing airline companies, including Air France, Malaysia Airlines, AirAsia, and Germanwings, in response to their real-life crisis incidents. Participants were introduced to each crisis (a total of 4) through a news article developed from a previously published story. Then, after each article reporting on the airline crisis, they were exposed to a response message from the airline. The findings show that when organizations express sadness in their messages, their sad emotion is transferred to the readers and leads to a higher organizational reputation and behavioral intention. Also, the use of a black-and-white logo in the context of sadness-present crisis response messages results in a better organizational reputation.