The integration of hazard evaluation procedures and requirements engineering for safety-critical embedded systems

Although much work has been done on assessing safety requirements in programmable systems, one very important aspect, the integration of hazard evaluation procedures and requirements engineering, has been somewhat neglected. This thesis describes the derivation and application of a methodology, HAZAPS (HAZard Assessment in Programmable Systems). The methodology assists at the requirements stage in the development of safety-critical embedded systems. The objectives are to identify hazards in programmable systems, construct and model the associated safety requirements, and, finally, to assess these requirements. HAZAPS integrates safety engineering and software modelling techniques. The analysis of more than 300 computer related incidents provided the criteria used to identify, select and modify safety engineering techniques. [Continues.

Safety Cases for Software Application Reuse

In traditional engineering industries it is common to reuse tried and trusted components as one of the means of ensuring safety. Some low-level software components, e.g. libraries, are reused, but there are difficulties in justifying the reuse of software due to the complexity of interactions in a typical software system. This paper addresses the issue of reusing software applications by considering how to extend the safety case for the use of software in one application based on its use in another. It proposes an approach to analysing the change between two contexts of use of a software system, including analysing small changes in the software, and illustrates this through some examples based on an analysis of a reactor protection system