中文摘要：

为了在提高过程监控效率的同时降低过程监控费用,针对同时监控过程均值和标准差变化的情形,研究可变抽样区间的指数加权移动平均控制图的经济设计问题。首先建立可变抽样区间,同时监控均值标准差指数加权移动平均控制图;其次对其进行经济设计,使单位时间期望费用函数最小,以确定控制图参数的最优值;然后利用遗传算法来寻找经济模型的参数最优解;最后对可变抽样区间同时监控均值标准差指数加权移动平均控制图的经济模型进行灵敏度分析和最优性分析。通过最优性分析得出结论：基于经济模型设计的可变抽样区间指数加权移动平均控制图比传统的控制图具有较小的费用。

英文摘要：

To improve the monitoring efficiency while reducing costs for process monitoring, the economic design of Exponential Weighted Moving Average （EWMA） control chart with Variable Sampling Intervals （VSI） for monitoring the process mean and standard deviation was discussed. VSI EWMA control chart for monitoring the process mean and standard deviation was established, and the economic model of VSI EWMA for monitoring the process mean and standard deviation control chart was developed. Thus the optimal values of the parameters would be determined by minimum expected cost. The genetic algorithm was used to search for the parameters＇ optimal values of the economic model. The sensitivity analysis and optimality analysis of proposed model was done, and the result showed that VSI EWMA control chart based on economic model had the smaller cost than the traditional control charts.