两个系统因素影响下的联合动态均值图

本文研究了两个系统因素下过程控制中样本容量和抽样区间的联合动态均值图（VSSI），并利用马氏链方法研究了动态均值图的性质。结果表明：VSSI图比VSS图，VSI图及FSSI图能更快地发现过程均值的漂移，因此，VSSI图对于快速检测遭受不同类型系统因素的过程更加有效，且对均值的敏感性增加，最后给出了联合动态均值图在生产中的一个应用实例。

A Combined Adaptive Mean Chart in Statistical Process Control with Two Assignable Causes

This paper considers a combined adaptive mean chart of variable sample size and sampling interval(VSSI) monitoring a process affected by two assignable causes and adopts the Markov chain approach to investigate the properties of this chart. Results show that VSSI chart can defect the shifts in mean quickly than VSS chart, VSI chart and FSSI chart. So VSSI mean chart is more efficient for the processes that are affected by several types of assignable causes, and more sensitive to changes in the mean. Finally, the advantage of using the combined adaptive chart is illustrated by an example from a production process.