Published online by Cambridge University Press: 24 September 2021
This paper studies the optimal allocation policy of a coherent system with independent heterogeneous components and dependent subsystems, the systems are assumed to consist of two groups of components whose lifetimes follow proportional hazard (PH) or proportional reversed hazard (PRH) models. We investigate the optimal allocation strategy by finding out the number  $k$ of components coming from Group A in the up-series system. First, some sufficient conditions are provided in the sense of the usual stochastic order to compare the lifetimes of two-parallel–series systems with dependent subsystems, and we obtain the hazard rate and reversed hazard rate orders when two subsystems have independent lifetimes. Second, similar results are also obtained for two-series–parallel systems under certain conditions. Finally, we generalize the corresponding results to parallel–series and series–parallel systems with multiple subsystems in the viewpoint of the minimal path and the minimal cut sets, respectively. Some numerical examples are presented to illustrate the theoretical findings.
$k$ of components coming from Group A in the up-series system. First, some sufficient conditions are provided in the sense of the usual stochastic order to compare the lifetimes of two-parallel–series systems with dependent subsystems, and we obtain the hazard rate and reversed hazard rate orders when two subsystems have independent lifetimes. Second, similar results are also obtained for two-series–parallel systems under certain conditions. Finally, we generalize the corresponding results to parallel–series and series–parallel systems with multiple subsystems in the viewpoint of the minimal path and the minimal cut sets, respectively. Some numerical examples are presented to illustrate the theoretical findings.
 $k$-out-of-
$k$-out-of- $n$ systems with respect to hazard rate ordering. Journal of Statistical Planning and Inference 142(7): 1878–1887.CrossRefGoogle Scholar
$n$ systems with respect to hazard rate ordering. Journal of Statistical Planning and Inference 142(7): 1878–1887.CrossRefGoogle Scholar $k$-out-of-
$k$-out-of- $n$ systems based on grouping of components. Advances in Applied Probability 51(2): 339–357.CrossRefGoogle Scholar
$n$ systems based on grouping of components. Advances in Applied Probability 51(2): 339–357.CrossRefGoogle Scholar $k$-out-of-
$k$-out-of- $n$ system with independent but nonidentical components. IEEE Access 8: 88464–88473.CrossRefGoogle Scholar
$n$ system with independent but nonidentical components. IEEE Access 8: 88464–88473.CrossRefGoogle Scholar $k$-out-of-
$k$-out-of- $n$ reliability systems with permutation monotone component lifetimes. Applied Stochastic Models in Business and Industry 32(5): 607–620.CrossRefGoogle Scholar
$n$ reliability systems with permutation monotone component lifetimes. Applied Stochastic Models in Business and Industry 32(5): 607–620.CrossRefGoogle Scholar $k$-out-of-
$k$-out-of- $n$ systems. Statistics and Probability Letters 135: 110–117.CrossRefGoogle Scholar
$n$ systems. Statistics and Probability Letters 135: 110–117.CrossRefGoogle Scholar