Handbook of Reliability, Availability, Maintainability and Safety in Engineering Design - Part 79 studies the combination of various methods of designing for reliability, availability, maintainability and safety, as well as the latest techniques in probability and possibility modelling, mathematical algorithmic modelling, evolutionary algorithmic modelling, symbolic logic modelling, artificial intelligence modelling, and object-oriented computer modelling, in a logically structured approach to determining the integrity of engineering design. . | 764 5 Safety and Risk in Engineering Design PRO RAM RELIABILITY AVAILABILITY MAINTAINABILITY EXPERT SYSTEM PROGRAM FOR ENGINEERING DESIGN EVALUATION HALIDE PUMP No 1 ASSEMBLY COMPONENT Plant FactWy Operation Area Section BuỂdng System Process Assembly Unit Component Hem REPORTS Fig. Knowledge base hierarchical data frame SYSTEM HALIDE TOWER ICS RAM Expert Systems Program CONTROL VALVE I Process Sequence Equpment Descfipirr 01010101040104 ENVIRONMENTAL PLANT SBS Levd Fiant Code 613 EP SULPHURIC ACID Opérai en Code 37 GAS CLEANING Section Code GC HALIDE TOWER System Code HLĨ HALIDE PUMP No 1 Assembly Code N s 37-07-130 CONTROL VALVE Component Code HV 37195 HALIDE PUMP No 1 CONTROL VALVE J ŨRID USĨ VIEW RD V1EWPFD Figure illustrates the questions option tab of the imbedded ExSys Expert System ExSys 2000 . In the illustration one question relates to temperature which refers to the expert system goal and is a design criteria constraint. Another question relates to a pressure constraint where both constraints need to be considered concurrently as the one impacts upon the other in a particular system design. Figure illustrates a multiple-choice question editor for application in the rule-based expert system. The multiple-choice question editor is used in establishing lists for questions relating to both temperature and pressure for application in the same rule-based expert system. The values of these variables are divided into ranges defined by the logical break points in the decision-making process . too low within or exceeding specification too high or critical . Variables are both numeric or string variables including expressions parenthesis Boolean operators trig functions and exponential functions. A numeric variable may have any value between its upper and lower bounds. For the purposes of defining IF-THEN expert system rules the value of the variable is divided into ranges defined by the logical break points in the decision-making process. For
