4.2 Frequency, wavelength and the speed of sound The speed of sound has a joint relationship with both the wavelength and the frequency of the sound. To see why, recall that at the end of Section 2.5, in connection with the wave produced by a tuning fork, I said ‘in the time it has taken for the source to go through one cycle of oscillation, the wave h
4.1 The experimental result One way to establish the speed of sound is to measure it experimentally. That is, one measures how long the sound takes to travel a known distance, and from this works out the speed. The answer turns out to depend somewhat on the prevailing temperature and humidity. At an air temperature of 14 °C the speed is 340 metres per second and at about 22.5 °C it is 345 metres per second. That is a change of speed of less than 1.5 per cent for an appreciable change of temperature. To a reasonable ap
6.2 Modes of managing systemically Now I want to describe some of the possibilities I see as being available in the repertoire of an aware systems practitioner able to connect with the history of systems thinking and with the new theories of complexity. David Robertson, in a presentation to the Society for Research into Higher Education in late 1998 entitled ‘What employers really, really want’ reported that: ‘research on employers in a number of English-speaking countries (an elite survey with senior corporate peo
5.4 Methodology, method, technique, and tools As you engage with systems thinking and practice you will become aware how different authors refer to systems methodologies, methods, techniques, and tools, as well as systems approaches. Having just spent some time explaining what I mean by a systems approach, I now want to distinguish between methodology, method, technique and tool. Several authors and practitioners have emphasised the significance of the term methodologies rather than methods in relation to Systems. A method i
18.2.6 Encouraging diffusion In general, innovations that are perceived as having relative advantages, being more compatible, less complex, observable, and trialable will diffuse more rapidly than other innovations.
12.3 Market pull The alternative market pull model suggests that the stimulus for innovation comes from the needs of society or a particular section of the market (Figure 55). These might be needs perceived by an entrepreneur or manufacturer like Shaw and his cat's-eyes or they m
11.7 Characteristics of inventors In their classic book The Sources of Invention (1969) John Jewkes, David Sawers and Richard Stillerman observe the following about inventors, whether working outside or inside an organisation. Inventors tend to be absorbed with their own ideas and to feel strongly about their importance and potential. Inventors can be impatient with those who don't share their optimism. Inventors are often isolated because they are
11.5.4 Analogy Analogy draws on similar situations to provide ideas for invention and design. Alexander Graham Bell used the analogy of the human ear when designing telephone apparatus to receive sound. As mentioned above, his first receivers were much better than his transmitters where the analogy with the ear didn't work as well. When devising their flying machine, the Wright brothers used the analogy of soaring birds twisting their wings to restore balance. They designed the wings of their aircraft to be
11.2 Step 1 – identification of the problem The activity of identifying a problem to be solved or a need to be met is a key step for the start of the innovation process. As you saw earlier there's a range of possible starting points. You've already seen examples where curiosity drives people to look for applications of certain scientific or technical principles such as Cockerell and air-cushion transport. Sometimes people identify an unsolved need, such as Percy Shaw and unlit roads. Sometimes people identify a need with an unsatisfact
10.3.1 Cats eyes and road conditions Sometimes the discontent comes from the fact that there isn't a product to satisfy a particular need. Percy Shaw was a road mender who was aware of the dangers of driving along unlit, often fog-bound, roads. One night in 1933 he was driving his car near his home in the north of England when his headlights were reflected in the eyes of a cat. This inspired him to invent the cat's-eye reflector that, when embedded at intervals in the centre of the road, reflected a vehicle's headlights and made
1.1.3 Features of diagrams As there is variety in the types of diagrams we can see and use we need to think more broadly about what diagrams are trying to represent. One distinction which follows on from the discussion above is:
Analogue representations: these diagrams look similar to the object or objects they portray. At their simplest they are photographs of real objects and at their most complicated they are colourful, fully labelled drawings of the inner workings o
Learning outcomes After reading this unit you should be able to: appreciate diagrams as a powerful aid to thinking and acting; distinguish between systems diagrams and diagrams helpful in systems work; demonstrate sufficient skills to ‘read’ and ‘draw’ a wide range of diagrams, following given conventions, that help improve your understanding of a situation; select diagrams suited to the needs of the situation you are investigating and the purp
4 Who are the users? This section reveals that ‘users’ can include a wide variety of people – not just the final purchasers or consumers of a product. The section also makes the case for strong user representation in the design process. Of course, it is not only me who uses the various products in my home; other people use them as well, both members of the family and visitors. Sometimes the range of users of a product, and their different needs, can be diverse. And in addition to the obvious or intend
3 Designing for users This section aims to develop your awareness of weaknesses in product designs, from the perspectives of usability and the variability in user populations, and to consider the opportunities for product design for different populations. Although most producer companies devote major resources to researching the market for their products, many products still appear on the market that seem not to have been designed with their user in mind. You must have experienced or noticed some dangerous,
5.4 Sedimentation When water has little or no movement, suspended solids sink to the bottom under the force of gravity and form a sediment. You will recall that we discussed a similar process in estuaries, with solids separating from the water. This process is called
sedimentation. In water treatment it is used to remove solids from waters which are high in sediment content, and also to remove particles rendered settleable by coagulation and flocculation. The theory of sedimentation would
3.4 Chemical characteristics of natural waters Since water is such a good solvent, it is not surprising to find many different chemical substances present in it. Water, on reaching a river, will contain inorganic and organic compounds which were dissolved as rainwater percolated through the soil and rocks. In addition, some gases will dissolve in rainwater during its passage through the air. The substances present in water may be conveniently grouped into: those from dissolved gases such as
3.3.3 Temperature All aquatic organisms have a fairly well-defined temperature tolerance range and this determines their distribution. Temperature affects the saturation concentration of dissolved oxygen (as seen in Table 2). An increase in water temperature will reduce the oxygen solubility as well as increase the metabolic activity of aquatic organisms. The combination of these two effects means that oxygen demand by organisms increases just when oxygen supply is being reduced. Coarse fish such as perc
2.4 Condensation As air rises it expands, owing to the decrease in pressure with height, and as it expands, in theory it cools at an average rate of 1°C for every 100 m of altitude. As the air cools, it becomes saturated with water vapour which condenses around small particles in the air. These particles may occur naturally, such as soil particles or salt particles residual to evaporation of sea spray, or they may be produced artificially during combustion. A measure of the necessary cooling to produce conde
3.7 Aftermath In the immediate aftermath of the disaster, it was vital to prevent any further collapses, especially on bridges of similar design. Two other bridges were built to a design similar to that of the Silver Bridge, one upstream at St Mary's, West Virginia and the other in Brazil at Florianopolis. The bridge upstream on the Ohio river, at St Mary's, was the focus of concern, and it was closed to traffic immediately after the disaster. The eye-bar design was actually quite widespread in other bridg
3.5 Design of the bridge The design of the original structure was governed by applicable standards in 1926. The official inquiry found that the design and build fell within those limits, the most important being the allowable stress in the eye-bar chain of 345 MPa. The steel was to be made with a maximum elastic limit of 520 MPa, with a safety factor on the strength of the steel of 2.75. It was argued at the time that over 70 per cent of the load was from the self-weight of the structure. Other suspension bridges of
