设计模式对软件可维护性影响的定量研究

软件可维护性是面向对象软件系统的重要质量属性之一,合理使用设计模式可以改善软件的可维护性。目前关于设计模式对软件可维护性影响的研究主要停留在定性分析阶段,缺少定量分析。针对这一问题,选取与软件可维护性相关的面向对象度量因子和可维护性指数,结合具体实例,研究了应用设计模式前后度量因子和可维护性指数变化情况,定量分析出设计模式对软件可维护性的影响。

基于强度导向的JavaScript代码协同混淆方法

代码混淆是一种对软件代码的保护技术,通过提高代码逻辑的分析难度对软件进行加固。目前,针对代码混淆的研究主要集中在单一的新混淆方法的提出及其效果分析,针对多种混淆方法进行协同混淆的研究较少。针对此问题,文章提出一种基于强度导向的JavaScript代码协同混淆方法,首先对参与混淆的多种独立混淆方法进行强度评估;然后根据评估结果调整混淆方法的执行顺序,获得比单一的多方法叠加更好的混淆效果。实验结果表明,该方法能够以较低的代价获得更好的代码混淆效果。

Inspection-replacement policy of system under predictive maintenance

In general, every system is in one of the three states： normal, abnormal, or failure state. When the system is diagnosed as abnormal state, it needs predictive maintenance, lfthe system fails, an identical new one will replace it. The predictive maintenance cannot make the system ＂as good as new＂. Under these assumptions, the reliability index and the inspection-replacement policy of a system were studied. The explicit expression of the reliability index and the average income rate （i.e., the long-run average income per unit time） are derived by using probability analysis and vector Markov process method. The criterion of feasibility for the optimal inspection-replacement policy under the maximum average income rate is obtained. The numerical example shows the optimal inspection-replacement policy can raise the average income rate when the optimal inspection-replacement policy is feasible.