Research on Safety Evaluation of Social Systems from Security Viewpoints

在该项目的第一阶段，安全传感器和/或警卫的最优分配问题被制定为一个图/网络问题，其中强调了多个最小割集的概念的重要性。多重最小割集的概念是作者于1989年首次提出的，它是图论和系统可靠性与安全性分析中著名的最小割集的一个自然的、一般的推广。算法来解决制定的图/网络问题的开发，它表明，该算法是非常有效的，从计算复杂性的角度来看。在该项目的第二阶段，我们考虑使用基于风险的方法的安全报警系统的设计和操作。首先，考虑检测误差对报警系统的风险，提出了报警系统数据项的优化设计，选择最优的最小数据项组合作为风险最小的组合。其次，考虑到报警系统的运行，保持报警系统的可靠性是非常重要的。为了系统地确定维修时间，提出了基于风险的方法：如果检测误差引起的风险大于期望值，则应进行维修。该标准始终保持风险水平合理，并最大限度地减少不可用时间。

At the first stage of the project, the problem of optimal allocation of security sensors and/or guards is formulated as a graph/network problem, where the importance of the concept of multiple minimal cut set is stressed. The concept of multiple minimal cut set, firstly introduced by the authors in 1989, is a natural and generic extension of minimal cut set which is well known in graph theory and systems reliability and safety analysis. The algorithm to solve the formulated graph/network problem is developed and it is shown that the algorithm is very effective from the view point of computational complexity.At the second stage of the project, we consider the design and operation of alarm systems for security using a risk-based approach. Firstly, the optimal design of data items for the alarm system is proposed with considering its risk caused by detection errors; the optimal minimal combination of data items can be selected as that with minimal risk. Secondly, considering the operation of an alarm system, it is very important to maintain the reliability of alarm system. To determine the maintenance time systematically, the risk-based approach is proposed as: The maintenance should be performed if the risk caused by detection errors is larger than the desired value. This criterion always keeps the risk level reasonable and minimizes the unavailable time.