This article proposes a novel preventive replacement policy based on condition monitoring and imperfect manual inspection for systems subject to a two-stage deterioration process, where the two-stage deterioration process is modeled by the white noise process and Brownian motion with a drift, respectively. The proposed preventive replacement policy is implemented using two thresholds: a failure threshold and a preventive threshold. Specifically, if the condition monitoring measurement is observed to cross the failure threshold, then the failure replacement will be carried out; and, if the condition monitoring measurement is observed to cross the preventive threshold while lower than the failure threshold, then the system needs to be checked by manual inspection, and the preventive replacement will be carried out once the system is found to be in the defective state. In this article, we consider that manual inspection is imperfect, namely, there is a probability that the defect will be unnoticed. By minimizing the expected cost per unit time, we obtain the optimal condition monitoring interval and preventive threshold. A numerical example is provided to demonstrate the performance of the proposed condition-based replacement policy. Comparisons are made with the existing work, which shows the effectiveness and superiority of the proposed policy.

本文提出了一种基于状态监测和不完善手动检查的新型预防性更换策略，该系统针对经历两阶段恶化过程的系统，其中两阶段恶化过程分别由白噪声过程和带漂移的布朗运动建模。拟议的预防性替换策略是使用两个阈值实现的：故障阈值和预防阈值。具体而言，如果观察到状态监视测量值超过故障阈值，则将执行故障替换；否则，将执行故障替换。并且，如果观察到状态监视测量值超过预防阈值而又低于故障阈值，则需要通过手动检查来检查系统，一旦发现系统处于故障状态，将进行预防性更换。在本文中，我们认为手动检查是不完善的，即存在缺陷未被发现的可能性。通过最小化每单位时间的预期成本，我们可以获得最佳的状态监视间隔和预防阈值。提供了一个数值示例来演示所提出的基于条件的替换策略的性能。与现有工作进行了比较，显示了拟议政策的有效性和优越性。我们获得最佳状态监测间隔和预防阈值。提供了一个数值示例来演示所提出的基于条件的替换策略的性能。与现有工作进行了比较，显示了拟议政策的有效性和优越性。我们获得最佳状态监测间隔和预防阈值。提供了一个数值示例来演示所提出的基于条件的替换策略的性能。与现有工作进行了比较，显示了拟议政策的有效性和优越性。