Effect of Low Reactivity Fuel on Reaction Wave Growth of Dual-Fuel Stratified Mixtures in a Rapid Compression Machine

For over 40 years, researchers have been studying homogenous charge compression ignition (HCCI) as a combustion strategy to improve the efficiency and emissions of the internal combustion strategy. Although early results were promising, it has been since discovered that HCCI engines only operate to their potential over a narrow load band. To remedy this, introducing inhomogeneities has been suggested as a method of controlling HCCI combustion in such a way to improve its usefulness. One such inhomogeneity is referred to as fuel octane number stratification and consists of port injecting a low reactivity fuel, allowing it to become well mixed, and then direct injecting a high reactivity fuel to introduce local mixture stratifications. Reciprocating engine and computational studies have shown this to improve efficiency and emissions of compression ignition engines, however, there has been little work done to explore octane number stratification on a per stroke basis in well-controlled conditions. The objective of this study is to utilize fuel octane number stratification combustion strategy to optically observe the influence of the low-reactivity fuel, propane, on the dynamics of the reaction zone growth. To accomplish this, a rapid compression machine (RCM) was used to perform experiments in which combustion was captured by a high-speed camera. The RCM was outfitted with heaters and a polycarbonate window to control the temperature and optically access the cylinder. In addition, the mixture composition of propane to n-heptane was varied while keeping the global equivalence ratio constant at three unique initial temperatures. The results of this study showed that ignition time, reaction front start location, and reaction front speed was sensitive to the amount of propane in the mixture. As propane content was decreased the time for the mixture to ignite relative to the start of compression decreased. Furthermore, as propane content decreased, the origin of the reaction front(s) increased in height along the cylinder wall. Reaction front velocity also increased as propane content decreased. Finally, through this work it was also discovered that ignition time and the reaction front speed of some mixtures were sensitive to changes in initial and compressed temperature

“CHANGELING HUMORISTS:” THE SPEECH ACTS OF THE EARLY MODERN ENGLISH FOOL

This dissertation pushes back against traditional theories of locating the fool within the carnivalesque traditions of subversion. Instead, it examines the ways in which the fool’s speech acts create an interstitial space to revise the humanist notion of civitas and transfer sovereignty from the royal court to the people. As a staged figure and a humanist trope flitting throughout seventeenth century discourses, the early modern English fool occupies a multimodal position and uses speech acts to democratize an access to voice before the English Civil War.Doctor of Philosoph

Anger problems and posttraumatic stress disorder in male and female National Guard and Reserve Service members

Anger is a common problem among veterans and has been associated with posttraumatic stress disorder (PTSD). This study aimed to improve understanding of how anger and PTSD co-occur by examining gender differences and differences by whether the triggering traumatic event is deployment-related vs. civilian-related in current service members. A representative cohort of Reserve and National Guard service personnel (n = 1293) were interviewed to assess for deployment- or civilian-related traumas, PTSD, and anger. The prevalence of self-reported anger problems was estimated among male (n = 1036) and female (n = 257) service members. Log Poisson regression models with robust standard errors were used to estimate the associations of problems with anger with PTSD and PTSD symptom severity for men and women. Self-reported anger problems were common among male (53.0%) and female (51.3%) service members. Adjusted prevalence ratios (PR) showed associations between anger and PTSD connected to both civilian- and deployment-related traumas (PR were 1.77 (95% CI 1.52–2.05) and 1.85 (95% CI 1.62–2.12), respectively). PTSD symptom severity was also associated with anger. This study was cross-sectional and so a causal relationship between PTSD and anger cannot be established. Problems with anger are common among male and female current Guard and Reserve members. These findings suggest that anger treatment should be made available to current service members and that clinicians should assess anger problems irrespective of gender. Future research should examine the effectiveness of anger treatment protocols by gender