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A study of evaluation methods centered on reliability for renewal of aging hydropower plants

Description
Hydropower generation is one of the clean renewable energies which has received great attention in the power industry. Hydropower has been the leading source of renewable energy. It provides more than 86% of all electricity generated by renewable sources worldwide. Generally, the life span of a hydropower plant is considered…

Hydropower generation is one of the clean renewable energies which has received great attention in the power industry. Hydropower has been the leading source of renewable energy. It provides more than 86% of all electricity generated by renewable sources worldwide. Generally, the life span of a hydropower plant is considered as 30 to 50 years. Power plants over 30 years old usually conduct a feasibility study of rehabilitation on their entire facilities including infrastructure. By age 35, the forced outage rate increases by 10 percentage points compared to the previous year. Much longer outages occur in power plants older than 20 years. Consequently, the forced outage rate increases exponentially due to these longer outages. Although these long forced outages are not frequent, their impact is immense. If reasonable timing of rehabilitation is missed, an abrupt long-term outage could occur and additional unnecessary repairs and inefficiencies would follow. On the contrary, too early replacement might cause the waste of revenue. The hydropower plants of Korea Water Resources Corporation (hereafter K-water) are utilized for this study. Twenty-four K-water generators comprise the population for quantifying the reliability of each equipment. A facility in a hydropower plant is a repairable system because most failures can be fixed without replacing the entire facility. The fault data of each power plant are collected, within which only forced outage faults are considered as raw data for reliability analyses. The mean cumulative repair functions (MCF) of each facility are determined with the failure data tables, using Nelson's graph method. The power law model, a popular model for a repairable system, can also be obtained to represent representative equipment and system availability. The criterion-based analysis of HydroAmp is used to provide more accurate reliability of each power plant. Two case studies are presented to enhance the understanding of the availability of each power plant and represent economic evaluations for modernization. Also, equipment in a hydropower plant is categorized into two groups based on their reliability for determining modernization timing and their suitable replacement periods are obtained using simulation.
ContributorsKwon, Ogeuk (Author) / Holbert, Keith E. (Thesis advisor) / Heydt, Gerald T (Committee member) / Pan, Rong (Committee member) / Arizona State University (Publisher)
Created2011
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Personifying and Objectifying Language as Indicators of Trust, Anthropomorphism, and Team Performance in Command-and-Control Human-Machine Teams

Description
Team communication facilitates team coordination strategies and situations, and how teammates perceive one another. In human-machine teams, these perceptions affect how people trust and anthropomorphize their machine counterparts, which in turn affects future team communication, forming a feedback loop. This thesis investigates how personifying and objectifying contents in human-machine team…

Team communication facilitates team coordination strategies and situations, and how teammates perceive one another. In human-machine teams, these perceptions affect how people trust and anthropomorphize their machine counterparts, which in turn affects future team communication, forming a feedback loop. This thesis investigates how personifying and objectifying contents in human-machine team communication relate to team performance and perceptions in a simulated remotely piloted aircraft system task environment. A total of 46 participants grouped into teams of two were assigned unique roles and teamed with a synthetic pilot agent that in reality was a trained confederate following a script. Quantities of verbal personifications and objectifications were compared to questionnaire responses about participants’ perceived trust and anthropomorphism of the synthetic pilot, as well as team performance. It was hypothesized that verbal personifications would positively correlate with reflective trust, anthropomorphism, and team performance, and that verbal objectifications would negatively correlate with the same measures. It was also predicted that verbal personifications would decrease over time as human teammates interact more with the machine teammate, and that verbal objectifications would increase. Verbal personifications were not found to be correlated with trust and anthropomorphism outside of perceptions related to gender, albeit patterns of change in the navigator’s personifications coincided with a co-calibration of trust among the navigator and the photographer. Results supported the prediction that verbal objectifications are negatively correlated with trust and anthropomorphism of a teammate. Significant relationships between verbal personifications and objectifications and team performance were not found. This study provides support to the notion that people verbally personify machines to ease communication when necessary, and that the same processes that underlie tendencies to personify machines may be reciprocally related to those that influence team trust. Overall, this study provides evidence that personifying and objectifying language in human-machine team communication is a viable candidate for measuring the perceptions and states of teams, even in highly restricted communication environments.
ContributorsCohen, Myke C. (Author) / Cooke, Nancy J. (Thesis advisor) / Chiou, Erin K. (Committee member) / Amazeen, Polemnia G. (Committee member) / Arizona State University (Publisher)
Created2022
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Rates of depression, anxiety, and stress in collegiate aviators

Description
The purpose of this research was to determine if students who are enrolled in a professional flight program exhibit significantly higher rates of depression, stress, and anxiety. This study compared professional flight students to non-professional flight students to determine whether professional flight students have higher rates of depression and anxiety.…

The purpose of this research was to determine if students who are enrolled in a professional flight program exhibit significantly higher rates of depression, stress, and anxiety. This study compared professional flight students to non-professional flight students to determine whether professional flight students have higher rates of depression and anxiety. In addition, this study sought to determine if there were higher depression, anxiety, and stress levels in upperclassmen (juniors and seniors) than in lowerclassmen (freshman and sophomore). Finally, upperclassmen and underclassmen within professional flight programs were compared to test if upperclassmen professional flight students exhibit higher rates for depression, anxiety and stress. These groups were compared to each other by using a survey that measures depression, anxiety, and stress. There were no statistically significant results. No singular group is more or less prone to depression, anxiety, or stress.
ContributorsJacobs, Destry (Author) / Niemczyk, Mary (Thesis advisor) / Cooke, Nancy J. (Thesis advisor) / Nullmeyer, Robert (Committee member) / Cline, Paul (Committee member) / Arizona State University (Publisher)
Created2019