Abstract
An escort formation is a phased mission system of systems (PMSoS), which is composed of multiple ships with different functions. The configuration of the formation and success criteria for a mission may vary in different phases. Reliability estimation for PMSoS is complicated due to the strong phase dependence of multiple systems. This paper proposes an improved multiple-valued decision diagram (MDD) algorithm to perform reliability estimation of a nonrepairable escort formation. First, a phased fault tree is established to describe the failure mode of an escort formation throughout a mission, which is simplified according to the common failure basic mission (module) (CFBM). Bottom events are sorted based on the CFBM, and the case method is adopted to generate an MDD from the simplified fault tree model. On this basis, the MDD method is adopted to estimate mission reliability. The performance of the improved MDD method is compared with that of a binary decision diagram (BDD) method and a general MDD method. The results show that the improved MDD method can offer lower computational complexity as well as a simpler model construction over the BDD method and general MDD method. A case study of an escort formation PMSoS is analyzed to illustrate the proposed MDD method, and the sensitivity and composite importance measure (CIM) of each system are evaluated.
Highlights
The escort formation is a typical phased mission system of systems (PMSoS), the corresponding platforms include destroyers, frigates, comprehensive supply ships and shipborne helicopters
Because the complexity of the model generation and evaluation algorithms highly depends on the number of nodes in the system model, the multiple-valued decision diagram (MDD) method is computationally more efficient than the binary decision diagram (BDD) method, especially for large PMSoSs. 2) By comparing Figs. 7 and 11, it is found that the improved MDD method proposed in this paper by simplifying the process of generating the MDD of the overall mission from the phased MDDs and simplifying the edges in the MDD model significantly improves the PMSoS evaluation efficiency compared with using the existing MDD method, even if the MDDs of the overall mission obtained by these two methods are the same
The definition of the PMSoS is given based on the PMS
Summary
The escort formation is a typical phased mission system of systems (PMSoS), the corresponding platforms include destroyers, frigates, comprehensive supply ships and shipborne helicopters. The system provides new types of reliability logic, such as a) the network relationship due to the multipurpose characteristics of each ship in the communication and command network, in our work, the network structure is transformed into a shared reliability block diagram; b) a plus system and its components may appear at the same or VOLUME 8, 2020 different phases, we have not studied it yet in this paper We call such a situation a phased mission system of systems (PMSoS) in this paper.
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