Modelling and evaluation of pulsed and pulse phase thermography through application of composite and metallic case studies

A transient thermal finite element model has been created of the pulsed thermography (PT) and pulse phase thermography (PPT) experimental procedure. The model has been experimentally validated through the application of four case studies of varying geometries and materials. Materials used include aluminium, carbon fibre reinforced plastic (CFRP) and adhesively bonded joints. The same four case studies have also formed a basis for comparison between three experimental techniques: PT, PPT and the more established ultrasonic (UT) c-scan.Results show PPT to be advantageous over PT due to its deeper probing as it is less influenced by surface features. Whilst UT is able to reveal all the defects in these case studies, the time consuming nature of the process is a significant disadvantage compared to the full field thermography methods.Overall, the model has achieved good correlation for the case studies considered and it was found that the main limiting factor of the PT model accuracy was knowledge of thermal material properties such as conductivity and specific heat. Where these properties were accurately known the model performed very well in comparison with experimental results. PPT modelling performed less well due to the method of processing the PT data which aims to emphasise small differences. Hence inaccuracies in inputted values such as material properties have a much greater influence on the modelled PPT data. The model enables a better understanding of PT and PPT and provides a means of establishing the experimental set-up parameters required for different components, allowing the experimental technique to be appropriately tailored to more complex situations including bonded joints or structures where several materials are present.The paper ends with a section on defect detectability based on thermal diffusivity contrast between the defect and the bulk material. It shows that in aluminium, because of its higher conductivity, greater thermal contrast is achieved for small differences in diffusivity. Regions where the diffusivity ratio between defect and bulk materials was insufficient to provide thermal contrast for defect identification were found. PPT phase data is shown to reduce the extent of such regions increasing the detectability of defects. Effusivity is introduced as a means of determining the thermal contrast between the defect and non-defective areas and hence establishing the defect detectability

Predation strategies in aerial feeding birds

The predation strategies of four species of aerial feeding bird, the Swallow, Hirundo rustica, Sand Martin, Riparia riparia, House Martin, Delichon urbica and Swift, Apus apus, are examined during their breeding season in Britain. The abundance of aerial insects upon which they feed increases in April and reaches a plateau in May which is maintained until September. Aerial insect density is higher nearer the ground, the spring rise in abundance occurs earlier, a greater proportion of larger insects are available and insect numbers fluctuate less than at higher levels. The arrival times of the different predator species into the breeding area are staggered and this is linked to their preferred prey and feeding station, and to the distribution of aerial insects. Throughout the breeding season the four species of bird are ecologically isolated with respect to feeding station in the air-space and various characters of the insect prey, primarily size and mobility. It is suggested that to coexist they segregate along a combination of axes of the feeding niche, although segregation in air-space may be the most effective. Morphological adaptation to feeding niche is shown for tail shape, wing-length and bill shape, which respectively influence manoeuvrability, mode of flight and prey handling ability of the predators. Both Sand Martin and Swallow show increases in their prey size and mobility niche breadths in favourable feeding conditions whilst all four species simultaneously show decreases in air-space niche breadths. It is postulated that both within and between species there is a tendency to switch between patch specialisation and prey specialisation. Current theories of optimal patch and prey choice are discussed in relation to this hypothesis. Under very adverse conditions prey size overlaps are small and, when they increase, air-space overlaps simultaneously decrease. This suggests competition between aerial feeding birds in adverse conditions. Swallows deliver more meals per unit time to larger broods, with an increase in the feeding rate of the male most evident. Males also increase their feeding rate to second broods, but these receive the same amount of food as first broods indicating a seasonal decline in meal size. There is a seasonal decline in size of prey items even though a higher density of available large (> 5 mm body length) insects occurs during second brood feeding. It is shown that the largest insects are in patches too far from second brood nests to be profitable. For first and second broods an optimal foraging strategy is to choose patches with the largest mean insect size, if the patches are within a given distance from the nest. Selection of an optimal size for fast-flying taxa is influenced by time and energy costs of pursuit. It is suggested that rearing larger than normal broods is constrained by the requirement of equal parental investment and the extra reproductive cost likely to be incurred by the male bird. Based on a very small sample of nests it is tentatively suggested that in colonial nesting Sand Martins there is an advantage in nesting early, with more birds feeding communally to aid location of food concentrations. Because individuals with centrally placed burrows are more able to minimise time spent deterring predators, and because early centre nesters suffer less time loss through competition at the nest-site, these same individuals have more time for locating other feeding birds and food concentrations. Thus the early season, centre colony nesters may collect more food per unit time and raise more off-spring. Comparison of aerial feeding bird communities in three zoogeographical regions indicates that selection for characters contributing to mode of flight and manoeuvrability are more important than selection for bill character. In Africa the Palearctic species maintain essentially the same feeding stations as in their breeding season although the air-space niche breadths show contraction and overlap is reduced except between Swift and House Martin. The indigenous species have different feeding stations and small air-space niche breadths, and where overlap is high the species involved apparently do not breed during the "winter" of the Palearctic species, possibly because of food shortage. The prey size niche breadth of the Swallow, H. rustica is very similar between Britain and Africa. With many more species utilizing this niche axis, compensation is likely along another axis, probably air-space

The CEDAR Project

We describe the plans and objectives of the CEDAR project (Combined e-Science Data Analysis Resource for High Energy Physics) newly funded by the PPARC e-Science programme in the UK. CEDAR will combine the strengths of the well established and widely used HEPDATA database of HEP data and the innovative JetWeb data/Monte Carlo comparison facility, built on the HZTOOL package, and will exploit developing grid technology. The current status and future plans of both of these individual sub-projects within the CEDAR framework are described, showing how they will cohesively provide (a) an extensive archive of Reaction Data, (b) validation and tuning of Monte Carlo programs against these reaction data sets, and (c) a validated code repository for a wide range of HEP code such as parton distribution functions and other calculation codes used by particle physicists. Once established it is envisaged CEDAR will become an important Grid tool used by LHC experimentalists in their analyses and may well serve as a model in other branches of science where there is a need to compare data and complex simulations.Comment: 4 pages, 4 postscript figures, uses CHEP2004.cls. Presented at Computing in High-Energy Physics (CHEP'04), Interlaken, Switzerland, 27th September - 1st October 200

Stability characterization of advanced injectors, design guide. Volume 2 - Operation of the computer program, Phase 3 Final report

Computerized stability design of time lag combustion system for liquid propellant rocket engin

Representations of power: A critical multimodal analysis of U.S. CEOs, the Italian Mafia and government in the media

In September 2008, the collapse of the bank Lehman Brothers led to a financial crisis and the worst recession since the Great Depression of the 1930s, threatening the entire global financial system. Some of the effects of the crisis included evictions, foreclosures and high and prolonged unemployment. Despite the fact that bankers and corporate executives are widely known to bear much of the blame for the crisis (“The origins of the financial crisis,” 2013), very few have actually been convicted of any crime. In addition, recent investigations of the relationship between the New York Federal Reserve and banks such as Goldman Sachs have revealed that even the regulators assigned to keep banks in check have become “too risk averse and deferential to the banks it supervised” (Bernstein 2014). Yet, the public has largely “learned to accept the implicit idea that some people have simply more rights than others. Some people go to jail, and others just don’t” (Taibbi 2014, xix). Similarly, in Italy, there is a large public consensus that many politicians and corporate executives are allies of Mafia groups such as ‘Ndrangheta and Cosa Nostra (who are engaging in activities such as setting up bogus firms in order to receive public subsidies, money laundering, fraudulent real estate schemes, etc.), yet few of them ever end up being prosecuted or serving jail time. In fact, while the government has created numerous task forces to combat Mafia groups, the ‘Ndrangheta has continued to gross billions of euros and has become a global presence, active in countries such as Germany as well as in South America (Conti 2014). The present paper seeks to understand why these CEOs and Mafia organizations are not often punished for their crimes and why there is little public outcry about it. We are concerned with one element that plays a crucial role: the lack of connection between their actions and their representation in the media. The representation of social actors in public discourse has always played an important role in how the public perceives them, how they are treated by legal and government entities and what the consequences of their actions are (van Leeuwen 1996). Discourses not only represent what is happening, but also evaluate, justify, highlight or background certain aspects of it (van Leeuwen, 2008, 6). Consequently, this multimodal critical discourse analysis will attempt to reveal less-than-obvious discursive strategies that (re)produce dominant ideologies of criminality and how groups in power, convicted or accused of crimes, are treated in the discourse. To do this, we take a qualitative approach that examines online newspaper articles reporting crimes committed by CEOs in the U.S. and Italian Mafia groups. Our focus is on the metonymic strategies