在CTCS-3级列控系统中,为了保证C2级向C3级场景转换的过程中列控系统实时性和安全性,采用统一建模语言(UML)活动图和分层赋时有色Petri网Hierarchical Timed Colored Petri Net(HTCPN)对等级转换过程进行建模。利用UML活动图对C2级向C3...在CTCS-3级列控系统中,为了保证C2级向C3级场景转换的过程中列控系统实时性和安全性,采用统一建模语言(UML)活动图和分层赋时有色Petri网Hierarchical Timed Colored Petri Net(HTCPN)对等级转换过程进行建模。利用UML活动图对C2级向C3级转换过程中车载设备、GSM-R网络、无线闭塞中心(RBC)之间信息流的传递过程进行建模,再从UML活动图中提取节点信息转换成HTCPN模型进行动态验证。通过对模型提取的数据仿真,分析列车行车速度和消息重发时间间隔对等级转换场景转换成功率的影响,验证模型的有效性。在CTCS-2级控车模式下,以顶棚速度(250 km/h)进行场景等级转换,转换成功率提高了0.2%。展开更多
Civil aircraft maintenance process simulation model is an effective method for analyzing the maintainability of a civil aircraft. First, we present the Hierarchical Colored Timed Petri Nets for maintenance process mod...Civil aircraft maintenance process simulation model is an effective method for analyzing the maintainability of a civil aircraft. First, we present the Hierarchical Colored Timed Petri Nets for maintenance process modeling of civil aircraft. Then, we expound a general method of civil aircraft maintenance activities, determine the maintenance level for decomposition, and propose the methods of describing logic of relations between the maintenance activities based on Petri Net. Finally, a time Colored Petri multi-level network modeling and simulation procedures and steps are given with the maintenance example of the landing gear burst tire of a certain type of aircraft. The feasibility of the method is proved by the example.展开更多
流控制传输协议(stream control transmission protocol,SCTP)是一种可靠的传输协议,2007年Internet工程任务组修订了52处缺陷并发布了SCTP新规范RFC4960,但仍缺乏形式化的描述和验证。赋时层次着色Petri网适用于从动态角度对复杂系统...流控制传输协议(stream control transmission protocol,SCTP)是一种可靠的传输协议,2007年Internet工程任务组修订了52处缺陷并发布了SCTP新规范RFC4960,但仍缺乏形式化的描述和验证。赋时层次着色Petri网适用于从动态角度对复杂系统进行建模,并能够用形式化的方法进行验证分析。因此,采用基于事件和基于状态的建模方法,提出了SCTP连接的赋时层次着色Petri网模型,该模型考虑了网络时延和丢失以及重传机制。通过CPN Tools分析,验证了SCTP连接过程的预期性质,并在RFC4960中描述的SCTP连接过程中发现了两类死锁问题。展开更多
文摘Civil aircraft maintenance process simulation model is an effective method for analyzing the maintainability of a civil aircraft. First, we present the Hierarchical Colored Timed Petri Nets for maintenance process modeling of civil aircraft. Then, we expound a general method of civil aircraft maintenance activities, determine the maintenance level for decomposition, and propose the methods of describing logic of relations between the maintenance activities based on Petri Net. Finally, a time Colored Petri multi-level network modeling and simulation procedures and steps are given with the maintenance example of the landing gear burst tire of a certain type of aircraft. The feasibility of the method is proved by the example.
文摘流控制传输协议(stream control transmission protocol,SCTP)是一种可靠的传输协议,2007年Internet工程任务组修订了52处缺陷并发布了SCTP新规范RFC4960,但仍缺乏形式化的描述和验证。赋时层次着色Petri网适用于从动态角度对复杂系统进行建模,并能够用形式化的方法进行验证分析。因此,采用基于事件和基于状态的建模方法,提出了SCTP连接的赋时层次着色Petri网模型,该模型考虑了网络时延和丢失以及重传机制。通过CPN Tools分析,验证了SCTP连接过程的预期性质,并在RFC4960中描述的SCTP连接过程中发现了两类死锁问题。