4.1 Domestic appliances and fossil fuels For this second case study I shall look specifically at the energy use of domestic ‘cold appliances’, that is freezers and refrigerators, and discuss whether efficiency measures can play a significant role in reducing their energy consumption. The reason for this is quite simple. For many years there has been well-documented evidence of the damage to the environment and cost to human life associated with the extraction, transport and consumption of fossil fuels such as coal and oil, from
3.3 Greenfreeze: the Greens fight back Some campaigners were not convinced by the arguments of refrigerator manufacturers and suppliers (who also happened to own some patents for HCFCs and HFCs) that the only solution, in the short to medium term, was to use the transitional compounds. They tried to demonstrate that there were practical alternatives. A group of scientists working with Greenpeace International designed a domestic refrigerator based on the use of hydrocarbons, using a mix of propane and isobutane for the refrigerant
3.2 The agreement to protect the ozone layer After a decade of controversy about the possible effects of CFCs, in 1985 British scientists discovered over the Antarctic a quite unexpected ‘hole’ in the ozone layer which was the size of the USA. This helped to galvanise the international community into action (though some who took part in the negotiations claim it played little part). By 1987 the first international agreement to control substances damaging to the ozone layer, the Montreal Protocol, was established. Interestingl
Acknowledgements Except for third party materials and otherwise stated (see terms and conditions), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence The material acknowledged below is contained in: Ordering the International: History, Change and Transformation (eds William B
2.1.1 Where did the attempt to define notions of rights internationally come from? To some extent, this ideology of rights was new because it was expressed at the international level with new vigour, with the horrors of the Second World War and the calculated extermination of Jews, gypsies and others in mind. The discourse of individual rights had a stronger impact on international politics than at any time previously, as did the notion of a right to national self-determination. Yet this new departure for international politics also built upon ideas about rights that had be
References 2.4 Worlds in motion: the importance of flows ‘The sea had welled up suddenly through thousands of tiny holes in this atoll's bedrock of coral.’ Do you recall this passage in Lynas's (2003) account of his first days on Tuvalu in Reading 1A? For me, this gives an impression of the islands being quite literally porous, a solid ground that reveals itself, now and again, to be not so solid after all. Lynas offers this particularly striking example of the island's openness to the world around it as evidence of a growing vulnerability that 2.2 Positive feedback and change Simple positive feedback loops are easily illustrated since they are the mechanism through which anything changes rapidly. Take for example the explosion of water hyacinth when introduced into new environments: Water hyacinth is a floating plant that has spread from South America to waterways around the world. It can cover the water so completely that it obstructs the movement of boats. Imagine a lake that is 10 2.2 Introduction to communication In Reading 2.1 I identified communication with others as being an important way in which humans learn. Unlike many other animals, we don’t have to interact directly with our Author(s): Introduction This unit will facilitate your own exploration of key environmental, social and economic threats that will converge to challenge communities in the near future. You will be required to develop this exploration according to three modes of modelling and communication: verbal, visual, and numeri 4.2.3 The significance of the distribution of energies Near room temperature (300 K), the average bundle of thermal energy associated with a particle is 0.026 eV (look back at Box 2 Temperature and energy). This is not going to do much damage to something stuck together with bonds that have an energy of a few eV – just as the average wage earne 5.6.3 Conformation and crystallinity If there are key connections between the chain configuration and crystallisation, you might also expect some more subtle effects from rotation about chain bonds. After all, polymer chains must be able to twist into the regular conformation demanded for crystal structures (Figure 57(a)). And what influence will rotation have on Module team John Hughes (Course Chair – Development) Kevin Gowans (Course Chair – Presentation) Brian Hambling (Author and Consultant) Tony Pearce Tammy Alexander (Graphic Designer) Sylvan Bentley (Picture Researcher) Sue Betteridge (Editor) Annette Booz (Compositor) Philippa Broadbent (Print Buyer) Sarah Crompton (Graphic Designer) 4.2 Fibre in the core network All new trunk transmission – that is, transmission between telephone exchanges – is now over optical fibre. Mostly it uses either PDH or SDH links. Year by year the data rates have increased, so that at the time of writing STM-64 products are available commercially. 4.1 Introduction
Additional material for this unit, by David Chapman, January 2005
The start of optical-fibre communication is generally identified with a paper published in 1966 (Kao and Hockham, 1966). It was not until about ten years later that it was commercially viable, but from then on there was more or less continuous development, with substantial research effort taking place both in industry and universities. Innovation continues today, and this additional material introduces some 7.4.5 Atomic layer deposition (ALD) For very thin conformal films, where rate is unimportant but precise thickness control is critical, a form of CVD allows deposition one monolayer at a time. One precursor gas is introduced into the chamber, which is then pumped away leaving only a monolayer adsorbed onto the wafer and chamber walls. The second precursor gas can then be supplied to complete the reaction at the surface, and then this gas is pumped away along with any gaseous reaction products. This cycle is repeated several tim 2.6 Turning the handle The owners of the original hand-cranked gramophones were instructed that the standard velocity for ‘seven-inch plates’ was about 70 revolutions per minute. The owner was also warned that failure to turn the plate at the correct speed would lead to a lowering of the pitch if turned too slow, or a raising of the pitch if turned too fast. It is doubtful if true reproduction of the recorded sound was ever achieved by the owners of these machines! A better power source was needed and as electr 2.1 Edison starts with cylinders I had a little gramophone; I'd wind it round and round, and with a sharpish needle it made a cheerful sound. Flanders, M. and Swann, D. (1977) ‘The Song of Reproduction’ from The Songs of Michael Flanders and Donald Swann, London, Elm Tree Books and St George's Press, p. 99 In 1877 the young American inventor Thomas Alva Edison finally completed development of an invention capable of ca 6.1 Defining amplitude Another important property of a sine wave we need to be able to specify is its amplitude. In essence, the amplitude of a sine wave is its size. Unfortunately there are various ways of defining what is meant by the size of a sine wave, and you are likely to come across many of them in material you look at outside this unit. Before I explain what our definition is, it will help matters if we look at what is meant by the average value of a sine wave. Figure 16 shows a sinusoidally a 12.2 Technology push The technology push model is a simple linear model that suggests that the innovation process starts with an idea or a discovery – it is sometimes called ‘idea push’ (Figure 51). Sometimes this is by a creative individual who has the knowledge and imaginatio
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