Failures of Steel Parts in Service

Presumably, the matter of failure of metal parts in service would arise very infrequently, in the thousands of years mankind knew how to make use of metals, before the introduction of steam power. There is much evidence, however, that failures bean to occur with distressing frequency from the time steam was applied to marine propulsion, and to railway engines early in the ninetee- nth century. Not that the steam of itself had anything to do with the failures, but its use as a prime mover implies normal working stresses higher than those empl-oyed when man, animal, water, and wind power were the sole means of making machinery go round. Not only were higher stresses used after the introduction of the steam engine, but the intermittent nature of the earlier prime movers would give place to long continued appli-cations of the reversed stresses imposed by a steam drive

Application of analysis techniques for low frequency interior noise and vibration of commercial aircraft

Finite element analysis (FEA), statistical energy analysis (SEA), and a power flow method (computer program PAIN) were used to assess low frequency interior noise associated with advanced propeller installations. FEA and SEA models were used to predict cabin noise and vibration and evaluate suppression concepts for structure-borne noise associated with the shaft rotational frequency and harmonics (less than 100 Hz). SEA and PAIN models were used to predict cabin noise and vibration and evaluate suppression concepts for airborne noise associated with engine radiated propeller tones. Both aft-mounted and wing-mounted propeller configurations were evaluated. Ground vibration test data from a 727 airplane modified to accept a propeller engine were used to compare with predictions for the aft-mounted propeller. Similar data from the 767 airplane was used for the wing-mounted comparisons

Fabrication and properties of gallium phosphide variable colour displays

The unique properties of single-junction gallium phosphide devices incorporating both red and green radiative recombination centers were investigated in application to the fabrication of monolithic 5 x 7 displays capable of displaying symbolic and alphanumeric information in a multicolor format. A number of potentially suitable material preparation techniques were evaluated in terms of both material properties and device performance. Optimum results were obtained for double liquid-phase-epitaxial process in which an open-tube dipping technique was used for n-layer growth and a sealed tipping procedure for subsequent p-layer growth. It was demonstrated that to prepare devices exhibiting a satisfactory range of dominant wavelengths which can be perceived as distinct emission colors extending from the red through green region of the visible spectrum involves a compromise between the material properties necessary for efficient red emission and those considered optimum for efficient green emission

Perspectives of Nuclear Physics in Europe: NuPECC Long Range Plan 2010

The goal of this European Science Foundation Forward Look into the future of Nuclear Physics is to bring together the entire Nuclear Physics community in Europe to formulate a coherent plan of the best way to develop the field in the coming decade and beyond.<p></p> The primary aim of Nuclear Physics is to understand the origin, evolution, structure and phases of strongly interacting matter, which constitutes nearly 100% of the visible matter in the universe. This is an immensely important and challenging task that requires the concerted effort of scientists working in both theory and experiment, funding agencies, politicians and the public.<p></p> Nuclear Physics projects are often “big science”, which implies large investments and long lead times. They need careful forward planning and strong support from policy makers. This Forward Look provides an excellent tool to achieve this. It represents the outcome of detailed scrutiny by Europe’s leading experts and will help focus the views of the scientific community on the most promising directions in the field and create the basis for funding agencies to provide adequate support.<p></p> The current NuPECC Long Range Plan 2010 “Perspectives of Nuclear Physics in Europe” resulted from consultation with close to 6 000 scientists and engineers over a period of approximately one year. Its detailed recommendations are presented on the following pages. For the interested public, a short summary brochure has been produced to accompany the Forward Look.<p></p&gt

The training of healthcare professionals: An expense or an investment?

Background. There is little information on the financial return of investment when funding the tertiary education of healthcare professionals (HCPs) in South Africa (SA).Objectives. To assess the cost-benefit of the Umthombo Youth Development Foundation (UYDF) scholarship scheme, which has supported the training of HCPs from rural areas in KwaZulu-Natal Province, SA, for the past 19 years, and to establish whether it is a worthwhile investment.Methods. This was an economic analysis to estimate the costs and economic value of UYDF’s investment in the training of HCPs, using a deterministic model developed in Excel 2010 (Microsoft, USA) to analyse the UYDF’s historical, numerical and economic data. Costs were measured in monetary terms, and a rate of return on investment was calculated over the working life of HCPs who had been supported by the UYDF.Results. With a >90% pass rate, the total cost of training the 254 graduates supported by the UYDF from 2009 to 2015 was estimated to be ZAR186 million. Graduates are expected to generate an estimated ZAR15 billion in lifetime earnings, which is equal to ZAR4 billion at 2015 prices, and represents an internal rate of return of 63%. Income tax paid on future earnings will be ~ZAR4 billion, assuming a 20 - 30% tax rate.Conclusions. The analysis has shown that the cost of HCPs’ education, where the annual pass rate is >90%, and >98% of graduates are employed, is an excellent investment. Consideration should be given to finding ways of improving the pass rate at institutions of higher learning and ensuring that graduates obtain meaningful employment if such returns on investment are to be seen on a national level

Mode identification in rapidly rotating stars

Context: Recent calculations of pulsation modes in rapidly rotating polytropic models and models based on the Self-Consistent Field method have shown that the frequency spectrum of low degree pulsation modes can be described by an empirical formula similar to Tassoul's asymptotic formula, provided that the underlying rotation profile is not too differential. Aims: Given the simplicity of this asymptotic formula, we investigate whether it can provide a means by which to identify pulsation modes in rapidly rotating stars. Methods: We develop a new mode identification scheme which consists in scanning a multidimensional parameter space for the formula coefficients which yield the best-fitting asymptotic spectra. This mode identification scheme is then tested on artificial spectra based on the asymptotic formula, on random frequencies and on spectra based on full numerical eigenmode calculations for which the mode identification is known beforehand. We also investigate the effects of adding random frequencies to mimic the effects of chaotic modes which are also expected to show up in such stars. Results: In the absence of chaotic modes, it is possible to accurately find a correct mode identification for most of the observed frequencies provided these frequencies are sufficiently close to their asymptotic values. The addition of random frequencies can very quickly become problematic and hinder correct mode identification. Modifying the mode identification scheme to reject the worst fitting modes can bring some improvement but the results still remain poorer than in the case without chaotic modes