According to the well-known age replacement policy, the system is replaced preventively at time $t$ or correctively at system failure, whichever occurs first. For a coherent system consisting of components having common failure time distribution which has increasing failure rate, we present necessary conditions for the existence of the unique optimal value which minimizes the mean cost rate. The conditions are mainly based on the signature which only depends on the system’s structure. The results are illustrated for linear and circular consecutive type systems.

中文翻译：

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关于一类相干系统的最佳年龄替换策略

根据著名的年龄替换政策，系统会及时进行预防性替换 $Ť$或纠正系统故障，以较早发生者为准。对于由具有相同故障时间分布且故障率不断增加的组件组成的相干系统，我们提出了使最小平均成本率最小的唯一最优值的存在的必要条件。条件主要基于签名，而签名仅取决于系统的结构。说明了线性和圆形连续类型系统的结果。