A MODELING FRAMEWORK TO EVALUATE PERFORMABILITY PARAMETERS IN GRACEFULLY DEGRADING SYSTEMS

The paper provides a systematic approach to modeling and assessing gra cefully degrading systems, exploiting the formalism offered by Petri n ets. The procedure followed is based on the definition of some fundame ntal modules, the composition of which allows a complete model of the system to be obtained. The model can then be solved by computer simula tion or analytically by means of a class of Petri nets to obtain inter esting performability parameters either at steady state and at varying times. The paper examines a number of real cases and describes the re sults obtained.