Abstract
A novel application of entropy to support Systems Engineering is presented with the specific objective of providing unambiguous and objective decision support to the engineer from the earliest stages of system development. Three facets of entropy are identified: How information passes around the system, How elements are oriented within the system, How the structured of the system is realized. From the outset, the Unified Modelling Language (UML) has been used as the language of choice for capturing system description and the work described in this thesis has made a significant contribution to its use within Thales for Systems Engineering. At the beginning of the project this was a novel application but the use of UML is now commonplace across the SE community. In order to capture the measures of entropy within the UML, a new generalised framework for interface definition is proposed covering six aspects: Information Protocol Management Security Carrier Physical, The work explores a range of techniques that are in common use, and through discussion of two specific, real-world examples conclude that minimising the entropy is entirely consistent with improvements suggested by other means; A wireless house alarm will reduce entropy but only for the larger house Clustering at the lower levels of networks reduces their entropy This new, unambiguous and objective measure of entropy provides engineers with a decision aid that can be applied early in the development lifecycle. The UML is used to describe systems and lends itself to incorporating this entropy measure. However, three simple rules result from the thesis that can be applied without formal calculation: 1 Minimise the number interfaces between entities and their bandwidth. 2 Either ensure all interfaces of an entity the same or ensure each is unique. 3 Ensure an entity has no more than one dependency on other system entities.