3.1 Refrigeration and chlorofluorocarbons A domestic refrigerator consists essentially of two elements. First, it has a well-insulated box that minimises the flow of heat energy from the warmer outside environment to the cold space inside. Second, it has a motor to circulate a cooling liquid or refrigerant which extracts heat from the cold space and carries it to the outside, where it is released, usually through a radiator at the back. Most refrigerators make use of the principle that when liquids vaporise – that is, change
3.1 Voyages of discovery and settlement In Section 2, we saw that there are momentous new and recently transformed flows that are impacting on island territories. Some flows have important precedents, and others may not be quite as novel as they first appear. In this section, we look more closely at some of the flows that have helped make, remake and sometimes unmake is
1.2.2 Change and response in the ‘meadows of the sea’ Midway along the northern shore of the Blackwater estuary lie the Old Hall Marshes on a peninsula three and a half miles long and lying between tidal creeks and mudflats (see Figures 3 and 15a). It is a wild, flat, remote area of mixed ha
1.2 Offshore fragments of industry The rise of global factories in the 1970s owed much to the rapid improvement in transport and communications technologies which took place at that time and which made it possible to keep in touch with, and control, production processes in different parts of the world. Just as significant was the fragmentation of industrial production whereby parts of the manufacturing process could be relocated over vast distances. Sewing in garment and footwear production, for instance, was among the
1.1 Introduction Looking back over the 1970s, it is perhaps hard now to appreciate just how dramatic were the changes to the global map of industry taking place at that time. As more and more of the world's industry shifted from the affluent nations to the poorer, less developed countries in search of a cheaper labour force, the global economic map had to be redrawn to take account of the borders crossed and the distances traversed by firms from wealthier countries seeking to generate higher profits by reloca
Groups and teamwork
Are you always the quiet one when it comes to group discussion? This free course, Groups and teamwork, will help you improve your working relationships with other people in groups of three or more. The course also deals with project life cycles, project management and the role of the leader.
First published on Mon, 10 Dec 2018 as Author(s):
Structural devices
Microelectronics has enabled designers of integrated circuits to exercise complete control over the electrical characteristics of each component they create. This free course, Structural devices, will illustrate how such control is achieved and the various methods that can be applied in differing circumstances.
First published on Tue, 07 May 2019 as
Introduction In this course we examine one factor that very often seems to be found skulking around close to problems and solutions: temperature. Almost whatever we do, wherever we are, temperature changes. Stay in the same spot and you'll find daytime and night-time temperatures can be markedly different. You may even find significant changes in temperature during the day. When moving you can encounter more rapid variations. For example, an aircraft might leave a tropical runway where the air tempe
References 1.1 Aim The activities and resources in this section engage you in an interdisciplinary investigation of your personal ecology by looking at a range of temporal, spatial, and organisational scales – from the personal to the global, from the short term to the long term. The aim is to gather evidence to help you r 6.2 Refining the specification The ideas for the boiler cut-out switch can now be based on some real knowledge about temperature effects. You are now ready to tackle the next exercise. List four temperature-dependent changes in mate 6.1 Review Let's see if we have made any progress in studying thermal effects. The following SAQ is based on Exercise 3, although this time I have a higher expectation of how much you should be able to do. 5.5 Summary of Section 5 The phase of a material is characterised by its physical state (e.g. solid, liquid or gas), a distinctive arrangement of the atoms, and its chemical composition. Material properties can change suddenly as the temperature increases or decreases, corresponding to changes of phase and the degree of order associated with the arrangement of atoms. Shape memory alloys are examples of a wide range of useful engineering materials that e 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 4.0 Licence Grateful acknowledgement is made to the following sources for permission to reproduce materia References Stage 5: Formulating measures of performance (how will we know when we have arrived?) The hard systems approach emphasises the need to have measurable means of assessing the efficacy of any potential solution or design, but recognizes that this may not always be possible. Conclusion This free course provided an introduction to studying Computing & IT. It took you through a series of exercises designed to develop your approach to study and learning at a distance, and helped to improve your confidence as an independent learner. 3.2 Making sense of the metaphor The metaphor of the juggler keeping the four balls in the air is a powerful way for me to think about what I do when I try to be effective in my practice. It matches with my experience: it takes concentration and skill to do it well. But metaphors conceal features of experience, as well as calling them to attention. The juggler metaphor conceals that the four elements of effective practice often seem to be related. I cannot juggle them as if they were independent of each other. I can imagine 8.5 Review We can sum up the distinctive features of wet etching with a few key points: Wet etching, in general, is a simple process to operate. Wafers are immersed in a solution for a while before being taken out, rinsed, and dried. However, certain etches require more sophistication. They may need one or more of the following: heating and agitation of the solution; reflux of vapours to maintain concentrations; protection of back side of the wafer; incorporation 8.3.2 Sputter etching: argon ion etching of gold One commercial process for cutting inkjet printer nozzles uses sandblasting. Not surprisingly, the surface finish is rather poor and there are issues with particles contaminating the devices. However, it is a physical process very like this that we need if we are to achieve a vertical etch profile. The key is directed bombardment by highly energetic particles. When processing on the microscale, these particles are not sand grains but ions accelerated towards the surface by an electric f
Exercise 7
