A Linguistic Hierarchical Evaluation Model for Engineering Systems

Abstract

This chapter proposes a linguistic evaluation model that takes into account the criteria of safety and cost. It outlines a generic framework for modeling system safety estimate using fuzzy rule-based evidential reasoning (FURBER) approach. The first step involves the identification of causes/factors that can be done by a panel of experts during a brainstorming session at the early concept design stages. The next step is to identify and make definite the fuzzy input and output variables. The three fundamental parameters used to assess the safety level of an engineering system on a subjective basis are the failure rate, consequence severity, and failure consequence probability. Subjective assessments are more appropriate for analysis using these three parameters, as they are always associated with great uncertainty. Other steps include constructing a fuzzy rule-base and fuzzy rule-base inference mechanism. The cost incurred for safety improvement associated with a design/operation option is usually affected by many factors that often have large uncertainties of estimation. Therefore, it may be more appropriate to model the cost incurred in safety improvement associated with the design option on a subjective basis.