The joint signature of coherent systems

Abstract

We investigate the joint signature of m coherent systems, under the assumption that the components have independent and identically distributed lifetimes. The joint signature, for a particular ordering of failure times, is an m‐dimensional matrix depending solely on the composition of the systems and independent of the underlying distribution function of the component lifetimes. The elements of the m‐dimensional matrix are formulated based on the joint signatures of numerous series of parallel systems. The number of the joint signatures involved is an exponential function of the number of the minimal cut sets of each original system and may, therefore, be significantly large. We prove that although this number is typically large, a great number of the joint signatures are repeated, or removed by negative signs. We determine the maximum number of different joint signatures based on the number of systems and components. It is independent of the number of the minimal cut sets of each system and is polynomial in the number of components. Moreover, we consider all permutations of failure times and demonstrate that the results for one permutation can be of use for the others. Our theorems are applied to various examples. The main conclusion is that the joint signature can be computed much faster than expected.

Equivalency in joint signatures for binary/multi-state systems of different sizes

“…Mohammadi [18] considered m parallel systems and investigated the classification problem of their failure time permutations according to the joint signatures. Furthermore, Mohammadi [19] presented discussions for m coherent systems on related issues and the joint reliability signature of several -out-of- systems was studied by Mohammadi [20].…”

“…joint signatures. Furthermore, Mohammadi [19] presented discussions for m coherent systems on related issues and the joint reliability signature of several 𝑘-out-of-𝑛 systems was studied by Mohammadi [20].…”

A new computation method for signature: Markov process method

“…(independent and identically distributed) component lifetimes, the signature of a coherent system was defined as a vector s = ( s 1 , s 2 , …, s n ), whose i th element s i represents the probability that the i th component failure causes the system to fail (see Samaniego, ). There are plenty of studies on system signatures, for example, Shaked and Shanthikumar (), Kochar, Mukherjee, and Samaniego (), Samaniego (, ), Navarro, Samaniego, Balakrishnan, and Bhattacharya (), Navarro, Samaniego, and Balakrishnan (), Eryilmaz and Tuncel (, ), and Mohammadi (). Due to the significance of system signature, it is meaningful to investigate efficient signature computation methods for different types of coherent systems in both numerical and analytical ways.…”