2007 MU theses - Freely available online
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Item Evaluation of ferrite, nickel-iron, amorphous metal, and nanocrystalline magnetic materials for pulsed power(University of Missouri--Columbia, 2007) Burdt, Russell A.; Curry, RandyA significant challenge in the design of circuits utilizing a magnetic switch is the accurate prediction of the magnetization dynamics. Several theoretical models are found in the literature for this purpose, however each is limited by assumptions restricting the model to a specific magnetic material, loss mechanism, or parameter space [1][2][3]. Therefore, an accurate prediction of the magnetization dynamics for a specific material is best obtained by consulting an empirical database. The empirical database found in the literature is extensive for many conventional magnetic materials, however the emergence of a new class of nanocrystalline magnetic materials has provided the motivation to conduct experiments to examine and characterize the magnetization dynamics of these emerging materials [1][4]. Experiments were conducted at the University of Missouri-Columbia to examine and characterize the magnetization dynamics of several conventional and emerging magnetic materials that included ferrite and several nickel-iron, amorphous metal, and nanocrystalline magnetic alloys. Two separate experiments were conducted, the first to replicate the '1 cos( )t [lowercase omega]' magnetic excitation inherent to pulse compression applications, and the second to replicate the square-pulse magnetic excitation inherent to a number of pulsed power applications. The '1 cos( )t [lowercase omega]' magnetic excitation experiments utilized the parameter space summarized in Table 1-1, whereas the square-pulse excitation experiments utilized the parameter space summarized in Table 1-2. For both experiments, a test stand was developed to generate an excitation pulse of the desired form and amplitude across the winding on a magnetic core. Also for both experiments, high fidelity diagnostics were utilized to measure the voltage and current of the saturating magnetic core in order to generate the BH curve and energy losses. The first chapter will discuss the previous work in this area, many important characteristics of the magnetic switch, as well as several applications that utilize the magnetic switch. The second chapter will examine theoretical ferromagnetism and will discuss the material properties of the magnetic cores evaluated in the experiments. The third chapter examines the '1 cos( )t [lowercase omega]' magnetic excitation experiments including the experimental objectives, test stand, data analysis, and experimental results. The fourth chapter examines similar aspects from the square-pulse magnetic excitation test stand. Finally, conclusions will follow and appendices will include the core reset current calculations, the physical dimensions of the cores evaluated, and the data analysis programs written in Matlab.--Background.Item A tall tower wind investigation of northwest Missouri(University of Missouri--Columbia, 2007) Redburn, Rachel; Fox, Neil I. (Neil Ian)With energy needs on the rise and our current energy consumption methods polluting the atmosphere, it is the right time to look at alternative forms of energy production. Six Tall Tower wind observation sites were studied in Northwestern Missouri in order to observe the wind resource available along with some interesting effects. A verification of existing wind maps for the State of Missouri has been performed to assist in the positioning of wind farms. Validation of current wind maps using observational data is of key importance because the observational data is actually coming from the heights at which wind turbines will operate. Diurnal variations in the wind fields were also studied, and thus far have shown that the area is capable of sustaining wind energy resources. Another aspect researched involved pairing tower data with wind profiler data to determine if profiler data can be used as a proxy for lower level winds. Plots of profiler winds versus tower winds were also analyzed to determine a threshold for indicating the presence of low-level jets. This method for the detection of the low-level jet has shown to be promising. Learning more about these aspects will allow for more to be known concerning the sustainability of wind energy resources in Missouri and help in determining if site locations will be efficient.Item Satisfaction across a multi-day outdoor recreation event(University of Missouri--Columbia, 2007) Montgomery, Timothy M.; Vaught, David R.The purpose of this study was to determine significant relationship between overall satisfaction with the day's experience and overall event satisfaction. In addition, the study determined demographic characteristics of Katy Trail Ride 2005 participants and measured participant satisfaction with specific site attributes over the course of a multi-day outdoor recreation event. Pearson r was used to determine significant relationship between site attributes and overall satisfaction on a daily basis. Additional statistics were computed to determine; if satisfaction differed within demographic profiles (Kruskal-Wallis), significant difference of attributes throughout the week (ANOVA), and significant differences between overall satisfaction with the day's experience and overall event satisfaction (chi square test of independence). Results indicated a spike in participant satisfaction upon completion of the multi-day event. Attributes correlating significantly with overall day satisfaction were facility cleanliness, facility maintenance, SAG service, current and accurate information, safety and security information, and natural and historical information. Results from this study provide information about managerial relevant concepts allowing recreation agencies to more efficiently facilitate programs and services within outdoor recreation settings.Item The effects of varying levels of object change on explicit and implicit memory for brand messages within advergames(University of Missouri--Columbia, 2007) D'Andrade, Nicholas; Bolls, Paul David, 1966-This study examined the effects of varying levels of object change in advergames on implicit and explicit memory for the brand sponsoring the game. For the purposes of this thesis, object change was defined as an object entering the screen of an advergame to which a player must react to with a motor response using a mouse or keyboard. This study utilized a 2 (level of object change) x 5 (advergame) repeatedmeasures experiment. Explicit memory was measured using a speeded recognition test. Implicit memory was measured via a word-fill task assignment. A signal detection analysis of explicit memory data revealed that participants were less able to recognize brands they had seen in high object change games versus brands in low object change games. There were no significant differences in implicit memory for high object change game brands and low object change game brands.Item The role of photography in Peru's truth and reconciliation process(University of Missouri--Columbia, 2007) Hoecker, Robin E.; Smith, C. Zoe (Cynthia Zoe)Using the methods of semi-structured personal interviews and a post test-only experiment, this study examined the creation and effects of a photography project initiated by the Commission of Peru. The interviews revealed how the project came to be and how it was put together. When selecting photographs, the curators had two goals in mind: reconstructing the chronology of the conflict as well as communicating the suffering of the victims. The quantitative results indicate that the exhibit is having the desired effects. A post test-only experiment (n=109) measured the effects of viewing the photographs on four variables of reconciliation: truth, forgiveness, trust in government and resentment. The study found that viewing the photographs increased respondents' confidence that they understood the truth about the conflict, but did not have any effect on their levels of trust in government or resentment. For those people who experienced traumatic events, viewing the photographs helped them to forgive. In contrast, respondents who did not experience traumatic events forgave less after seeing the pictures. Drawing from conflict theory, the study explores the role that photography could play in the reconciliation process on both national and personal level.