2.8 Good times and bad

The music industry, like any other large industrial business, had good times and bad times. By 1924 the burgeoning of radio broadcasting in the United States caused a severe downturn in record and equipment sales, leading to amalgamations and bankruptcies of many of the record companies. Actually, radio broadcast studio technology proved of great importance to the record industry. The sensitive microphones and electronic amplifiers used in broadcast studios offered improved characteristics th
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5.7 Vibrating air column: reflection at the end of an air column

When a sound wave reaches the end of an air column, it is clear that it will be reflected if the tube end is closed. You only have to imagine yourself standing some distance, let's say 50 metres, away from a flat wall. If you shout, you will hear an echo – the reflection of the sound wave you projected.

There is one difference, though, between the reflection of a sound wave and the reflection of the wave on a string that you met previously. When a sound wave is reflected from a closed
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9.2 Dynamic range

The quietest sound we can hear corresponds to a pressure wave with an amplitude of about 10 μPa, which is a very small pressure amplitude indeed. It is about 0.000 000 01 per cent of nominal atmospheric pressure, and the resultant displacement of the eardrum is less than a tenth of the diameter of a hydrogen molecule.

At the upper end of the scale, a sound that is distressingly loud might typically correspond to a pressure wave with an amplitude of 0.01 per cent of nominal atmospheric
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17.1 Part 4: 1 Revising your understanding

By now, it is probably apparent that those of us writing this unit are enthusiastic about the possibilities for systems thinking and complexity thinking. Our enthusiasm extends beyond just thinking, to applying systems thinking to a situation in the world that we experience as complex for the purpose of doing something about it. Our focus is on improving a situation experienced as problematical or on grasping some opportunity. It is the act of relating systems thinking to action in a given co
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5.6 Developing the Open University hard systems method

When the writers of the course T301 Complexity Management and Change, the predecessor to T306 (the course from which this unit is taken), started in 1982 they had to decide what to include and what to leave out (just as we have). They started with the systems analysis approach of the engineers De Neufville and Stafford (1971), which had been developed in a civil engineering group at the Massachusetts Institute of Technology (MIT). De Neufville and Stafford defined systems analysis as
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5.5 Experiences that motivated the development of systems methods

I have already introduced various systems methods. Behind all of these methods, there has generally been a champion, a promoter aided by countless co-workers, students, etc. To paraphrase the French sociologist of technology, Bruno Latour: we are never confronted with a systems method, but with a gamut of weaker and stronger associations; thus understanding what a method is, is the same task as understanding who the people are.

A method, like any social technology, depends on many peopl
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2.4 Appreciating epistemological issues

Common sense tells me my experience and understanding of the world are limited. I am 173 cm in height. That limits my view of the world. It may not matter much that I cannot see what my house looks like from above but it does mean there will be things going on in the roof I may not notice until they impinge on areas that I can experience.

More significantly, there is a real limitation on understanding the experiences of other people. You might tell me about your experience but your desc
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2.3 Taking responsibility for your own learning

Not much of this unit conforms to the traditional pattern I mentioned earlier – the theory-example-exercise pattern. In particular, you will find you are expected to discover much of it for yourself. Why is this? This is a legitimate question and deserves a full answer. One year, a student at a residential summer school complained I had not taught him properly. I was, he told me, an expert and so why did I not demonstrate how to tackle the problem he was working on and pass my expertise on
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10.10 Government policy, legislation and regulations

To a certain extent it's possible for governments to stimulate invention by providing incentives for manufacturers to develop new products and for consumers to buy and use them. One example of this process is in the field of vehicles powered by alternative fuels.

In the USA the Energy Policy Act of 1992 (EPAct) was passed to reduce US dependence on imported petroleum. The EPAct required federal and governmental departments with fleets over a certain size to acquire a percentage of alter
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5.9 Membrane filtration

Membrane filtration is a process whereby particles smaller than about 10−2 mm (which can pass through sand filters) are removed using synthetic polymeric membranes and a high pressure. The membrane effectively acts as a sieve.

It is increasingly becoming popular as an advanced treatment process for water (especially for removal of Cryptosporidium) and wastewater (where water reuse takes place), and various possibilities are:

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3.2 Dissolved oxygen

Organic and inorganic nutrients are the basic food supply essential for maintaining the plants and animals in natural watercourses. Equally essential to aquatic life is a supply of oxygen, needed for respiration. Oxygen dissolved in the water is also needed in the biodegradation of organic matter by aerobic (oxygen-consuming) bacteria. A measure of this oxygen demand can be obtained experimentally and is defined as the biochemical oxygen demand (BOD). The BOD i
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2.11 Storage

In a given fixed space at any phase of the hydrological cycle, there is an inflow and an outflow of water, the rates of which vary with time. The total cumulative difference between inflow and outflow is the storage. So within that space there is a body of water whose mass is not directly controlled by instantaneous values of inflow and outflow. For example, in river flow the movement of the whole body of water in the channel is generally downstream, yet a given reach contains a volume whose
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2.5 Air circulation

At this stage, air circulation enters and plays a dual role. Firstly, winds transmit moisture horizontally from one location to another. In this way, moisture derived from oceanic evaporation can be transported many miles to a land mass. Secondly, convective or vertical currents arising from unequal heating or cooling can transmit moisture upwards. When it cools, some of the water vapour condenses. It is from these currents that most precipitation develops.


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2.2.3 Doing

Finally, learning how to act or perform in particular ways is essential for the development of all kinds of intellectual and physical skills. For example, we need to be able to learn how to create a variety of kinds of written communication, or how to present complex information in a clear diagram, or to decide how a team will structure its work, and so on. No amount of explanation of how to compose a clear technical report, for example, would provide convincing proof that we could actually p
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1.4 Defining reflection

Reflection is both an academic concept and also a word in common use, combining ideas of thinking, musing, pondering and so on. This everyday meaning is a good basis from which to start: reflection is very much to do with thinking. However, one of the most important things about reflection is that it enables us to think about our own thinking – about what it is that we know or have experienced. Such reflection might be summed up in the phrase, ‘the mind's conversation with itself’.

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1.3 Reflection and course study

Many of the units on the OpenLearn website include self-assessment questions and activities designed to require you to stop and think, sometimes to take action. This is also true of many Open University courses because Open University course teams typically want students to question what they read and to try out ideas for themselves. Every time you pause to do your own thinking in this way, you are reflecting on what you have learnt.

This unit includes several activities that are specif
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1.2 Learning beyond course study

Learning how to learn has become an important goal in higher education. There is a national context in which an emphasis on ability to learn has come to prominence. It is now widely asserted that an ability to learn is as important an outcome of university study as knowledge of a discipline. This is a view put forward strongly by employers, for example, who have an interest in the employability of graduates and the skills they bring into the work place. It is a view which has been reiterated
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3.4.1 Fracture surface

One half of the eye at the joint is shown in Figure 38(a), and it shows two breaks in the limbs either side of the pin-hole. Although both appear brittle in this picture, in fact one side showed signs of ductile deformation. The way it had fractured was unique when compared with the other eye b
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3.3.4 Examining the parts

Brittle fractures were discovered quickly in the mass of debris hauled from the river. Such samples became the focus of increasing effort as time went by, simply because they were unexpected. So the possible failure mechanisms were immediately narrowed down when brittle fractures of critical components started to emerge from the river.

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3.3.3 Reassembling the parts

As the wreckage was pulled from the river it was examined and identified, and any failures of the metal components were recognised and tagged. This was a mammoth task, given that virtually the whole bridge had fallen into the water, including all the road decks, trusses, chains and hangers, eye bars and the two towers. The parts were then reassembled and all the failed or fractured components photographed and catalogued. Over 90 per cent of the bridge components were collected together and re
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