344 research outputs found

    A critical assessment of UH-60 main rotor blade airfoil data

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    Many current comprehensive rotorcraft analyses employ lifting-line methods that require main rotor blade airfoil data, typically obtained from wind tunnel tests. In order to effectively evaluate these lifting-line methods, it is of the utmost importance to ensure that the airfoil section data are free of inaccuracies. A critical assessment of the SC1095 and SC1094R8 airfoil data used on the UH-60 main rotor blade was performed for that reason. Nine sources of wind tunnel data were examined, all of which contain SC1095 data and four of which also contain SC1094R8 data. Findings indicate that the most accurate data were generated in 1982 at the 11-Foot Wind Tunnel Facility at NASA Ames Research Center and in 1985 at the 6-inch by 22-inch transonic wind tunnel facility at Ohio State University. It has not been determined if data from these two sources are sufficiently accurate for their use in comprehensive rotorcraft analytical models of the UH-60. It is recommended that new airfoil tables be created for both airfoils using the existing data. Additional wind tunnel experimentation is also recommended to provide high quality data for correlation with these new airfoil tables

    Corporate governance and employees in South Africa.

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    Focusing on employees as stakeholders, we analyse corporate governance initiatives in South Africa encouraging and requiring companies to look beyond their shareholders' interests. Successive non-binding codes and the provisions of the recent Companies Act 2008 promoting this have been lauded by many commentators. The 2008 Act provides certain opportunities for employees and their representatives to exercise influence at the margins. We nevertheless question how far current corporate governance initiatives are adequate to promote employee interests. On the basis of three case studies of how companies have responded to employees as stakeholders, we conclude that in fact more stringent regulation is required

    Stadium Architecture and Regional Economic Development: International Experience and the Plans of Durban

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    For the FIFA World Cup 2010, South Africa plans to invest heavily. The positive economic effects that the country is hoping for stand in contrast to almost all statistical ex-post studies. This contribution emphasises that these results, usually from research under-taken in the USA, can only be generalised to a limited degree. The density of sports venues in developed countries is so high, that the marginal effects of new stadia are necessarily limited. We also emphasise that stadium design around the world was not hitherto adequately targeted towards positive economic effects. The example of Durban and its plans for a new iconic stadium is used to illustrate fundamental principles of stadium design and their embedding in a re-urbanisation process that have to be undertaken in order to consciously achieve positive regional economic effects

    ‘We secured the tussac’: Accounts of ecological discovery, exploitation and renewal in the Falkland Islands

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    Sheep farms dominate the Falkland Islands landscape and have for over a century. The introduction of sheep, and several other species, has significantly transformed the ecology of this archipelago—the near elimination of tussac grass being one of the most notable changes. Tracing back to early accounts of tussac grass in the ‘Falklands’, this paper captures its discovery, exploitation and current stage of renewal, including a closer look at the connections between tussac and livestock farming, as well as parallel trends in other countries. We narrate changing relations between people and tussac grass using a combination of interview data, historical accounts and scientific literature. Tussac is presented as a historical bellwether of shifting trends in local farm and environmental management in this isolated archipelago. Shifts in land ownership, grazing management methods and conservation efforts are bringing momentum to a period of renewal across the Falklands

    Numerical simulation of ultrasonic flowmeters

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