中文摘要：

为了更准确地刻画马尔可夫可修系统的运行特征，建立了多运行水平马尔可夫可修系统模型．在该系统中，工作状态被聚合成几个不同的运行水平．应用离子通道理论和Laplace变换方法，给出系统在不同运行水平逗留时间密度函数的Laplace变换及平均逗留时间．分析了系统访问不同运行水平的次数，得到它们的分布律及平均值．通过一个数值示例说明了结论的应用，表明了该模型的有效性．

英文摘要：

To describe precisely the performance characteristics of Markov repairable systems, the model of Markov repairable systems with multi-operating levels was introduced. According to their performance levels, the working states were aggregated into several operating levels in the systems. The Laplace transforms of probability density functions of times that the system stays in distinct operating levels were obtained by using ion-channel theory and Laplace transformations. Also, the mean staying time of them were given. The numbers that the system visits distinct operating levels were studied and their was given to illustrate the results from the research means were presented. A numerical example in this paper.