As an extension of the traditional signed digraph model , layered digraph models make hazard and operability analysis more thorough and systematic , which improves the capability of the expert system in identification of the potential safety hazards in the chemical processes .

它拓展了传统的有向图模型，从而使危险和可操作性分析的结果更全面、更系统，提高了专家系统全面挖掘化工过程中潜在的安全危险问题的能力。

In simple introduction content of all directions spreads notional base , be based on actual project project to use background , point out content of all directions sheds the crucial question in running , built gift multidimensional the digraph model of authority .

在简单介绍第四方物流概念的基础上,基于实际工程项目应用背景,指出第四方物流运作中的关键问题,建立了赋予多维权的有向图模型。