Generalized inteGrated importance measure for system performance evaluation: application to a propeller plane system uoGólniona miara zinteGrowanej ważności komponentów jako narzędzie oceny wydajności systemu: zastosowanie w odniesieniu do układu śmiGłowca : state vector of the components at time t ( ( )) X t Φ system structure function at time t and range {0,1, , [7,8] studied the IIM in system lifetime and semi-Markov process to evaluate the change of the system performance, respectively.The IIM evaluates the rate of system performance change due to a component changing from one state to another. The IIM simply considers the scenarios when the transition rate of a component from one state to another is constant. This may contradict the assumption of the degradation, based on which system performance is degrading and therefore the transition rate may be increasing over time.On the other hand, the Weibull distribution is one of the most commonly used lifetime distributions in reliability modeling and lifetime testing [25]. It has been used in many different engineering applications to model complex data sets, such as life tests [15], fault diagnosis [4,5], oral irrigators [16], et al. The Weibull distribution and its variants can accommodate increasing, constant or decreasing failure rates [10]. Thus, one may extend the IIM to a new importance measure that considers the scenarios where the transition rate of a component changing from one state to another as a time-dependent function. Typically, one may consider the conditional probability distribution of a component sojourning in a state is the Weibull distribution, given the next state that the component will jump to. On the basis of such consideration, this paper proposes a new importance measure. The research on the new importance measure can identify the most important component during three different time periods of the system lifetime, which is corresponding to the characteristics of Weibull distributions. The paper then derives some probabilistic properties. It also analyzes the properties of the proposed importance measure of the parallel-series systems and the series-parallel systems, respectively. A real-world example is borrowed to illustrate the proposed importance measure.The rest of the paper is as follows. Section 2 extends the IIM. The corresponding properties of IIM in the Weibull distribution are analyzed for typical parallel-series system and series-parallel system structures in Section 3. An application is presented to illustrate the proposed method in Section 4. Section 5 gives the conclusion of this paper.
The extended IIM for system performance under Weibull distributionsIn this paper, the state space of component i is {0,1,…, M i } and the state space of the system is{0,1,…, M}. State 0 represents the complete failure state and state M (M i ) is the perfect functioning state. The states are ordered from the complete failure state to the perfect functioning state.We assume that the levels of maintenance cost and the system states ( 0 1) a...