中文摘要：

屏蔽数据是指引起系统失效的真实原因不得而知，即失效原因可能是系统组件的某个子集。一般地，屏蔽数据下非齐次泊松过程 （non-homogeneous Poisson process, NHPP）类软件可靠性叠加模型中参数的极大似然估计比较复杂，因为叠加模型不能分解成几个简单的NHPP模型。本文主要研究基于屏蔽数据下叠加模型中参数的极大似然估计，评估软件系统的可靠性。最后通过一组模拟数据，说明极大似然估计效果良好。

英文摘要：

The masked data are the system failure data when the exact cause of the failures might be unknown. That is, it is the subset of components that causes system failures. In general, the maximum likelihood estimation （MLE） of parameters are difficult to find when the masked data exist, because the superposition non-homogenous Poisson process （NHPP） software reliability model cannot be decomposed into independent NHPP models. In this pa-per, the MLE of software reliability with masked data is studied based on superposition NHPP models. Finally, a nu-merical example based on simulation data is given to illustrate the good performance of MLE