Abstract: Context modeling is the essential task to build context-aware systems， it’s the key for applications to understand and utilize context. Considering the lifecycle of context， it can be divided into persistent context and dynamic context； the latter can be further divided into state context and transition context. Many researchers have done lots of works about persistent context and state context modeling， but there are few works dealing with transition context. In this paper， a formal dynamic context model based on ontology using OWL is proposed， as well as a context fusion and consumption mechanism implementation. Also， some programming principles are provided for applications and a system called Auto-Lock Door is demonstrated to show how systems get benefit from the model.

Key words: pervasive computing, context, context-aware, ontology

摘要： 上下文建模是开发上下文感知系统的核心任务，它是应用理解和使用上下文的关键。按照生命周期的长短，上下文可以分为持久上下文和动态上下文，而后者可以进一步分为状态上下文和转换上下文。许多研究者在持久上下文和状态上下文建模方面做了大量的工作，但涉及到转换上下文的工作却很少。因此提出了一个采用OWL语言描述的基于本体的形式化的动态上下文模型，以及一个上下文融合和消费机制的实现。同时，为应用提供了一些编程原则并以一个自动门禁系统的演示说明了系统如何从这个模型中受益。

关键词: 普适计算, 上下文, 上下文感知, 本体