Design usually requires taking into account not only physical and biological constraints, but also economic, political, social, ethical, and aesthetic ones.
Learning Goal 2a
All technologies have effects other than those intended by the design, some of which may have been predictable and some not.
Learning Goal 2b
Side effects of technologies may turn out to be unacceptable to some of the population and therefore lead to conflict between groups.
Learning Goal 3a
Almost all control systems have inputs, outputs, and feedback.
Learning Goal 3bc
The essence of control is comparing information about what is happening to what people want to happen and then making appropriate adjustments. This procedure requires sensing information, processing it, and making changes.
Learning Goal 3d
In almost all modern machines, microprocessors serve as centers of performance control.
Learning Goal 4a
Systems fail because they have faulty or poorly matched parts, are used in ways that exceed what was intended by the design, or were poorly designed to begin with.
Learning Goal 4b
The most common ways to prevent failure are pretesting of parts and procedures, overdesign, and redundancy.
For Grades: 9-12
Learning Goal 1
In designing a device or process, thought should be given to how it will be manufactured, operated, maintained, replaced, and disposed of and who will sell, operate, and take care of it. The costs associated with these functions may introduce yet more constraints on the design.
Learning Goal 2
The value of any given technology may be different for different groups of people and at different points in time.
Learning Goal 3
Complex systems have layers of controls. Some controls operate particular parts of the system and some control other controls. Even fully automatic systems require human control at some point.
Learning Goal 4
Risk analysis is used to minimize the likelihood of unwanted side effects of a new technology. The public perception of risk may depend, however, on psychological factors as well as scientific ones.
Learning Goal 5
The more parts and connections a system has, the more ways it can go wrong. Complex systems usually have components to detect, back up, bypass, or compensate for minor failures.
Learning Goal 6
To reduce the chance of system failure, performance testing is often conducted using small-scale models, computer simulations, analogous systems, or just the parts of the system thought to be least reliable.