Premium
The joint signature of coherent systems
Author(s) -
Mohammadi Leila
Publication year - 2017
Publication title -
naval research logistics (nrl)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 68
eISSN - 1520-6750
pISSN - 0894-069X
DOI - 10.1002/nav.21773
Subject(s) - signature (topology) , joint (building) , permutation (music) , function (biology) , joint probability distribution , mathematics , independent and identically distributed random variables , exponential function , matrix (chemical analysis) , component (thermodynamics) , series (stratigraphy) , computer science , polynomial , discrete mathematics , algorithm , combinatorics , statistics , random variable , mathematical analysis , physics , architectural engineering , geometry , materials science , evolutionary biology , acoustics , engineering , composite material , biology , thermodynamics , paleontology
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.