Motivation for Optimisation Sample Clauses

Motivation for Optimisation. A particularly challenging aspect of a multi-objective analysis of a complex system under design that was briefly mentioned in the preceding section is that of design exploration. Embedded systems are characterised by sharing of information and hardware resources which means that large numbers of configuration and reconfiguration options are available not only at design time but also at run time, due to the use of shared processors and communication channels. When the functions of a system can be delivered by multiple different configurations, designers are faced with hard optimisation problems, especially when the design space is very large (as is typical for complex systems). The dependability of individual configurations can of course be determined using safety analysis and verification techniques such as fault tree analysis and model checking. However, satisfying dependability requirements with optimal use of resources and minimal costs requires additional technological support in the form of a global optimisation process. Where it is possible to fulfil all dependability requirements within economical and technical bounds, the architecture that has minimal costs is the optimisation goal. If all dependability requirements cannot be met with acceptable costs, then the problem becomes one of finding architectures that achieve optimal trade-offs between dependability and cost. It is widely accepted that the various formulations of the above represent hard, combinatorial multi- objective optimisation problems that can only be approached systematically with the aid of optimisation techniques and computerised algorithms that can effectively search for optimal solutions in large potential design spaces. As an example problem, one mechanism that designers have for altering the safety and reliability characteristics of systems is the substitution of single components with fault tolerant schemes that incorporate redundant components and subsystems. The technique has been shown to work well in combination with measures that ensure the diversity of replicated (hardware or software) components and minimise the possibility of common cause failure. However, the decision on the optimal location and level of replication of components is a non-trivial task and this is especially true as systems increase in size and complexity. This problem of maximising reliability via such replication within given cost and other (e.g. weight) constraints has come to be known as the Redu...