Effect of CO2 Dilution on the Structure and Emissions from Turbulent, Non-premixed Methane-Air Jet Flames

This investigation gives a comparison of the variation of temperature and gas compositions in lifted, turbulent non-premixed methane–air jet flames firing vertically into still air with different carbon dioxide diluent concentrations in the fuel jet. The carbon dioxide mole fraction ranged from 0 to 0.22 and was varied with a fixed jet velocity so that dilution-induced extinction was achieved. The effect of the changes due to this dilution on the post-flame emissions was investigated. Similarly, visual observation of the changes in the flame structure in mixture fraction space at different diluent mole fraction has been studied. An examination of the changes in the flame length, lift-off height, flame temperature, composition, and on the emission indices of the species in the post-flame region were made. They showed an increase in the flame's lift-off height, a decrease in the overall flame length, a reduction in the flame temperature and a reduction in the NOx concentration at various levels of dilution of carbon dioxide in the fuel

Effect of Reynolds number on particle interaction and agglomeration in turbulent channel flow

The work described in this paper employs large eddy simulation and a discrete element method to study turbulent particle-laden channel flows at low concentrations (particle volume fraction 10−4–10−5), including particle dispersion, collision and agglomeration. Conventional understanding of such flows is that particle interactions are negligible, this work however demonstrates that such interactions are common at large Stokes numbers in turbulent flow. The particle-particle interaction model is based on the Hertz-Mindlin approach with Johnson-Kendall-Roberts cohesion to allow the simulation of cohesive forces in a dry air flow. The influence of different flow Reynolds numbers, and therefore the impact of fluid turbulence, on agglomeration behaviour is investigated. The agglomeration rate is found to be strongly influenced by the flow Reynolds number, with most of the particle-particle interactions taking place at locations close to the channel walls, aided by the higher turbulence levels and concentration of particles in these regions

Engaging Undergraduates in Science Research: Not Just About Faculty Willingness.

Despite the many benefits of involving undergraduates in research and the growing number of undergraduate research programs, few scholars have investigated the factors that affect faculty members' decisions to involve undergraduates in their research projects. We investigated the individual factors and institutional contexts that predict faculty members' likelihood of engaging undergraduates in their research project(s). Using data from the Higher Education Research Institute's 2007-2008 Faculty Survey, we employ hierarchical generalized linear modeling to analyze data from 4,832 science, technology, engineering, and mathematics (STEM) faculty across 194 institutions to examine how organizational citizenship behavior theory and social exchange theory relate to mentoring students in research. Key findings show that faculty who work in the life sciences and those who receive government funding for their research are more likely to involve undergraduates in their research project(s). In addition, faculty at liberal arts or historically Black colleges are significantly more likely to involve undergraduate students in research. Implications for advancing undergraduate research opportunities are discussed

Large-scale trials of a real-time acoustic backscatter system for solids concentration measurement during nuclear waste cleanup

Real time in situ characterisation of solids concentration would aid operational understanding and improve efficiency in many industrial systems. This is especially true in the processing of legacy nuclear wastes where hazardous material is encountered. Acoustic methods have been previously demonstrated for the measurement of concentration in solid-liquid systems at a small scale. This study explores the use of the ultrasound array research platform (UARP) for backscatter measurements of concentration at a large scale in a dynamic settling system. The theory of acoustic measurement of solids concentration is described for both backscatter based attenuation and backscatter power methods. Acoustic based backscatter power and attenuation measurements are compared to laboratory analysed samples. Ultrasonic solids concentration analysis is shown to reveal flow dynamics within the settling tank

Gaze behaviours of elite golfers: Does task difficulty influence quiet eye?

Gaze behaviours of elite golfers: Does task difficulty influence quiet eye

Perceptual-cognitive expertise in golf putting

Perceptual-cognitive expertise in golf puttin

Prediction of horizontal gas–liquid segregated flow regimes with an all flow regime multifluid model

The generalized multifluid modelling approach (GEMMA) has been developed to handle the multiplicity of flow regimes and the coexistence of interfaces of largely different scales in multiphase flows. The solver, based on the OpenFOAM reactingEulerFoam family of solvers, adds interface resolving-like capabilities to the multifluid solver in the cells occupied by large interfaces. In this paper, GEMMA is further developed to predict stratified and slug flow regimes in horizontal ducts. The suppression of the turbulence and the wall-like behaviour of large interfaces is modelled with an additional dissipation source. This enables an accurate prediction of the velocity and of the turbulence kinetic energy in a stratified channel flow and the capturing of the formation and the travel of liquid slugs in an annulus. Large interfaces are identified and tracked, not only in the smooth and wavy stratified regimes but also in the much more perturbed interfaces of liquid slugs. The present work confirms GEMMA to be a reliable approach to provide all flow regime modelling capabilities. Further development will be focused on large interface momentum-transfer modelling, responsible for the overestimation of the interfacial shear and the limited liquid excursion during slugs, and the extension to interface break-up and the entrainment of bubbles and droplets, to handle the entire range of regimes encountered in horizontal flows

Reasoning with heuristics

Which rules should guide our reasoning? Human reasoners often use reasoning shortcuts, called heuristics, which function well in some contexts but lack the universality of reasoning rules like deductive implication or inference to the best explanation. Does it follow that human reasoning is hopelessly irrational? I argue: no. Heuristic reasoning often represents human reasoners reaching a local rational maximum, reasoning more accurately than if they try to implement more “ideal” rules of reasoning. I argue this is a genuine rational achievement. Our ideal rational advisors would advise us to reason with heuristic rules, not more complicated ideal rules. I argue we do not need a radical new account of epistemic norms to make sense of the success of heuristic reasoning

Climate change and food security: health impacts in developed countries.

BACKGROUND: Anthropogenic climate change will affect global food production, with uncertain consequences for human health in developed countries. OBJECTIVES: We investigated the potential impact of climate change on food security (nutrition and food safety) and the implications for human health in developed countries. METHODS: Expert input and structured literature searches were conducted and synthesized to produce overall assessments of the likely impacts of climate change on global food production and recommendations for future research and policy changes. RESULTS: Increasing food prices may lower the nutritional quality of dietary intakes, exacerbate obesity, and amplify health inequalities. Altered conditions for food production may result in emerging pathogens, new crop and livestock species, and altered use of pesticides and veterinary medicines, and affect the main transfer mechanisms through which contaminants move from the environment into food. All these have implications for food safety and the nutritional content of food. Climate change mitigation may increase consumption of foods whose production reduces greenhouse gas emissions. Impacts may include reduced red meat consumption (with positive effects on saturated fat, but negative impacts on zinc and iron intake) and reduced winter fruit and vegetable consumption. Developed countries have complex structures in place that may be used to adapt to the food safety consequences of climate change, although their effectiveness will vary between countries, and the ability to respond to nutritional challenges is less certain. CONCLUSIONS: Climate change will have notable impacts upon nutrition and food safety in developed countries, but further research is necessary to accurately quantify these impacts. Uncertainty about future impacts, coupled with evidence that climate change may lead to more variable food quality, emphasizes the need to maintain and strengthen existing structures and policies to regulate food production, monitor food quality and safety, and respond to nutritional and safety issues that arise