Technologies are often modified almost as soon as they are implemented as knowledge accumulates through informal learning and formal R&D. Operating experience, pressure from users, follow-up inventions and competition from rivals all induce changes and developments in novel technologies. After all, fuel efficiency of the stationery steam engine improved 20 fold in 170 years. These sessions examine the creative and competitive forces that improve technologies and often result in their destruction and replacement. Papers consider the way in which knowledge grows, spreads and then becomes obsolete.

Improvements in know-how may be the gradual accumulation of incremental changes as a technology develops along a dominant trajectory. Sometimes technical changes are radical and display unforeseen shifts in direction, often prompted by outside forces and newcomers to an industry. These changes may upset just one part of the supply chain – valves to transistors to integrated circuits, for instance - and leave users unaware. Other changes may bring complete shifts in know-how – steam to electric or analogue to digital, for example. These dramatic changes often force the emergence of new disciplines and new sets of craft skills.

These sessions assemble papers that look at broad themes such as the way in which knowledge based economies transform themselves over time. It will also focus on the detail of these transformations – the way in which technologies are modified in practice with experience and R&D and look at how these improvements get selected for use. How do engineers know what they know? How does learning take place? How far are manufacturing skills tacit and learned on the job, and how far are they the result of formal training?

The reality of these stories is of particular interest – the setbacks, false starts and blind alleys that characterise the reality of engineering development. In this context, we include papers on “rejected” technologies that have failed or lost their niche in the restless market place for know how. There is also a keen interest in the forces that generate these transformations – entrepreneurs, innovative engineers, the pressures of war, government policy and – above all – the relentless selection mechanism of the competitive process in market economies. Bringing the story up to date, what are the lessons for training and education if technologies are so restless?