It is very difficult to predict the behavior of rules set in active database. The termination of rules set can be analyzed by triggering graph (TG). It is necessary to calculate all cycles in TG to judge exactly the termination of rules set. This paper analyzes the termination of active rules set in Object - Oriented Database, produces the method of judging the termination of rules set, deduces the algorithm of calculating all cycles of triggering graph and the algorithm of judging termination of rules set.

针对航空气象保障中常用的几种天气雷达图像的特性,采用双正交小波变换方法,应用嵌入式零树编码和自适应算术编码,提出了一套合理的图像压缩编码软件方案.试验表明,该方案是解决天气雷达回波图像存储和远程传输的一种有效途径,并在气象业务工作中发挥了重要作用.