中文摘要：

在已有VSSI—X控制图基础上，本文结合B＆L转换规则，提出了新的控制图运行方式。运用马尔可夫链方法，推导出新运行方式下控制图的性能指标ATS和AATS，给出了相应的费用函数。通过数值实例，本文将改进的控制图与现有的SS、VSI和VSSI X控制图进行了比较分析，发现在缩短报警时间、节约费用方面，改进控制图有着明显的优势。进一步，本文运用遗传算法搜索出了改进控制图的最优参数解。

英文摘要：

Based on the existing VSSI X control chart, a new run procedure of the control chart is proposed with application of B＆L switching rule. The expressions of statistical performance indexes ATS and AATS have been derived through the Markov chain approach. The cost function is derived. A comparison of the improved control chart and existing SS, VSI and VSSI X charts is presented to an actual case, and the results show the improved control chart has the savings in terms of shorting .the time to signal and reducing cost. Further, the genetic algorithm is employed to search the optimal solution of the economic design for the improved control chart.