虚拟实体是数字孪生五维模型中重要的组成部分,其行为模型描述了物理实体在外部环境与内部运行机制作用下的实时响应及行为.针对离散制造车间数字孪生虚拟实体行为模型缺乏统一描述与精确定义的难题,提出一种使用基于值的离散事件系统规范(VDEVS)对行为模型进行描述的方法.在原有数字孪生五维模型基础上定义了数字孪生车间虚拟实体分层模型,实现了其与数字孪生车间物理实体的一一映射.通过对传统离散事件系统仿真规范(DEVS)进行扩展提出了VDEVS,从而更加精确地描述离散制造车间复杂系统级、系统级、单元级虚拟实体的行为.最后,针对某加工单元,利用基于VDEVS的方法对其行为模型进行了描述.

In combination with the characteristics of Web system under B/S architecture,a new model of RBAC based on role-con￣trol er is put forward in this article. It introduces the concept of the control er between the authority and role and constitutional y divides the authorities of web system into two types,the view and the data. Dealing with the authority becomes more flexible and more suit￣able for the special need of the authority of web system. It is proved that the model can be wel adaptable to different needs of the au￣thority of WEB system in the project of manufacturing information system.