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Master of Engineering / Turbulent propagating premixed flames are encountered in spark ignition engines, gas turbines, industrial burners, as well as in vented gas explosions. In all these applications, the flame fronts interact with complex solid boundaries which not only distort the flame structure but directly affect the propagation rate in ways that are not yet fully understood. This thesis aims to provide both a quantitative and qualitative understanding of the link between overpressure, flame front wrinkling and turbulence levels generated in the propagating medium. This is an issue of importance for the provision of improved sub-models for the burning rates of premixed flames. An experimental chamber was constructed where controlled premixed flames were ignited from rest to propagate past solid obstacles and/or baffle plates strategically positioned in the chamber. Laser Doppler Anemometry was used to measure the velocity field and turbulence fields while pressure transducers were used to obtain pressure-time traces. In addition to this Laser-Induced Fluorescence of the Hydroxyl radical is was to image the flame front as it consumes the unburnt fuel captured in the re-circulation zone behind the main obstruction. The thesis reports on the effects of various parameters such as the inclusion of grids and obstructions, blockage ratio, and repeated obstacles to explore possible correlations between the pressure and the flow-fields. Pressure, velocity and LIF images were correlated and analysed to prove the significance of grid location and number on overall turbulence intensity. Corresponding flow field parameters such as flame front wrinkling, peak overpressure and RMS all combine to conclusively demonstrate their interaction and influence to turbulence intensity. By progressively positioning more grids further downstream, consequent rises in the flow field parameters and the establishment of positive trends indicates the overall significance of kernel development and flow disturbances in relation to turbulence generation.

Thesis (Ph.D.)--Australian National University, 2004. / Errata slip inserted.

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Soot is a common byproduct of hydrocarbon based combustion systems. It poses a risk to human and environmental health, and can negatively or positively affect combustor performance. As a result, there is significant interest in understanding soot formation in order to better control it. More recently, the need to study soot formation in engine relevant conditions has become apparent. One engine relevant parameter that has had little focus is the ambient pressure. This body of work focuses on the formation of soot in elevated pressure environments, and a number of investigations are carried out with this purpose. Laminar coflow diffusion flames are used as steady, simple soot producers. First, a commonly studied flame configuration is further characterized. Coflow flames are frequently used for fundamental flame studies, particularly at elevated pressures. However, they are more susceptible to buoyancy induced instabilities at elevated pressures. The velocity of the coflow is known to have an effect on flame stability and soot formation, though these have not been characterized at elevated pressures. A series of flames are investigated covering a range of flowrates, pressures, and nozzle diameters. The stability limits of coflow flames in this range is investigated. Additionally, an alternative strategy for scaling these flames to elevated pressures is proposed. Finally, the effect of coflow rate on soot formation is evaluated. Identification of fundamental flames for coordinated research can facilitate our understanding of soot formation. The next study of this work focuses on adding soot concentration and particle size information to an existing fundamental flame dataset for the purpose of numerical model validation. Soot volume fraction and average particle diameters are successfully measured in nitrogen-diluted ethylene-air laminar coflow flames at pressures of 4, 8, 12, and 16 atm. An increase in particle size with pressure is found up to 12 atm, where particle sizes plateau. Particle size in the annulus is more sensitive to pressure. Next, the development of an alternative particle size measuring technique is studied. Time Resolved Laser Induced Incandescence (TiRe-LII) is a commonly used technique to measure soot concentrations and particle size at atmospheric pressure. However, Laser Induced Incandescence (LII) models suffer from an incomplete understanding of the effects of elevated pressures on the absorption, annealing, and cooling of soot. The present study focuses on what affect the laser temporal pulse shape and duration may have on particle sizing. TiRe-LII in flames at 1 and 15 bar is carried out, using laser pulses with tophat or Gaussian temporal profiles of varying duration. Mono-disperse equivalent primary particle diameters are calculated using the KAUST LII model. Little difference in particle sizing is found for different laser pulses. However, this data will be useful for validating the KAUST LII model when absorption and poly-dispersion are accounted for. In an effort to move one step closer to logistical fuel studies, the sooting tendencies of a number of liquid fuels are studied at pressures up to 10. Of parallel relevance, a sooting index for surrogate development is evaluated for elevated pressure applications. The Yield Sooting Index (YSI) methodology is applied to 11 normal, cyclic, and branched alkanes. When referencing to two n-alkane fuels, the YSI of n-alkanes determined at atmospheric pressures accurately reflects the relative sooting tendencies of these fuels at elevated pressures. The relative sooting tendencies of cyclo- and methyl-alkanes have a lower pressure sensitivity than n-alkanes.

Magister Scientiae (Biodiversity and Conservation Biology) - MSc (Biodiv and Cons Biol) / Ichthyophonus hoferi has been diagnosed in multiple species at the Two Oceans Aquarium, this study focuses on Rhabdosargus globiceps (White stumpnose). I. hoferi is a mesomycetozoan parasite that multiplies in blood rich organs in the fish hosts causing a wide range of clinical signs resulting in organ dysfunction. I. hoferi can be diagnosed from microscopic examination of tissue squash preparations, culture, polymerase chain reaction (PCR) and histopathology. In the literature only lethal methods of diagnosis are described. The development of a non-lethal diagnostic tool for disease monitoring is vital for collections where euthanasia of specimens is not possible.

<div>Chirped-probe pulse femtosecond coherent anti-Stokes Raman scattering (CPP fs CARS) was used to study high pressure gas-phase thermometry. The experimental measurements were</div><div>mostly performed in a static gas cell and in a canonical flat flame burner. The purpose of this study is to provide insights for the future rocket relevant combustion measurements. </div><div><br></div><div><div>Chirped-probe pulse femtosecond coherent anti-Stokes Raman scattering (CPP fs CARS) was used to study high pressure gas-phase thermometry. The experimental measurements were mostly performed in a static gas cell and in a canonical flat flame burner. The purpose of this study is to provide insights for the future rocket relevant combustion measurements. </div></div><div><br></div><div><div>The optical effects associated with ultrashort pulse propagation in the high-pressure system were investigated. For example, the femtosecond pulse can receive large amount of frequency chirp when transmitting through thick glass windows of the optical section in the high-pressure system. The effects of pump and Stokes frequency chirp were investigated both experimentally, by inserting disks of SF11 glass into the pump and Stokes beam paths to study the flame thermometry, and theoretically by incorporating pulse chirp into the TDDM simulations to calculate the Raman excitation efficiency. Meanwhile, the ultrashort pulses can experience self-phase modulation in the high-pressure gas medium. The effects of self-phase modulation (SPM) on the power spectra of femtosecond pulses will have significant impact on the fs CARS profile. On the other hand, the extend and the behavior of SPM reply on the laser intensity and are also species-specific. The optimal laser intensities in high-pressure gas mediums like N2, O2, CO2 and CH4 were investigated.</div></div><div><br></div><div><div>To prepare for future rocket relevant combustion studies, CPP fs CARS thermometry was developed for CO2, O2 and H2. Especially for CO2 and O2, they have close vibrational frequencies but very different coherence dephasing rates. Relative concentration between CO2 and O2 can then be extracted by using a short probe delay, and the temperature information can be determined by using long probe delays and the O2 transitions will not interfere with CO2 and nonresonant contribution of the CARS signal can be suppressed. CO2 CPP fs CARS measurements inside the high-pressure high-temperature gas cell were presented and discussed. Collisional narrowing effects for CO2 especially for high gas number density situation were discussed. </div></div>

Researchers raise concerns that the diagnostic approach can create stigma and lead to clinical inferences that focus on dispositional characteristics at the expense of situational variables. From social cognitive theory to strict behavioral approaches there is broad agreement that situation is at least as important as disposition. The present study examined the clinical inferences of graduate student clinicians randomly presented a diagnosis (borderline PD) or no diagnosis and either randomly given context information or no context information before watching a videotaped clinical interaction of a fabricated client. Responses to a questionnaire assessing dispositional or situational attributions about the client’s behavior indicated a diagnosis of borderline personality disorder did not significantly increase dispositional attributions and did not significantly moderate the importance of contextual factors. A notable difference between the attributions made by psychodynamic and third wave behavioral respondents was observed. Conceptual and experimental limitations as well as future directions are discussed.

Bayesian networks have been applied to many different domains to perform prognostics, reduce risk and ultimately improve decision making. However, these methods have not been applied to military field and human performance data sets in an industrial environment. Methods frequently rely on a clear understanding of causal connections leading to an undesirable event and detailed understanding of the system behavior. Methods may also require large amount of analyst teams and domain experts, coupled with manual data cleansing and classification. The research performed utilized machine learning algorithms (such as Bayesian networks) and two existing data sets. The primary objective of the research was to develop a diagnostic and prognostic tool utilizing Bayesian networks that does not require the need for detailed causal understanding of the underlying system. The research yielded a predictive method with substantial benefits over reactive methods. The research indicated Bayesian networks can be trained and utilized to predict failure of several important components to include potential malfunction codes and downtime on a real-world Navy data set. The research also considered potential error within the training data set. The results provided credence to utilization of Bayesian networks in real field data – which will always contain error that is not easily quantified. Research should be replicated with additional field data sets from other aircraft. Future research should be conducted to solicit and incorporate domain expertise into subsequent models. Research should also consider incorporation of text based analytics for text fields, which was considered out of scope for this research project.