A state/event fault tree(SEFT)is a modeling technique for describing the causal chains of events leading to failure in software-controlled complex systems.Such systems are ubiquitous in all areas of everyday life,and ...A state/event fault tree(SEFT)is a modeling technique for describing the causal chains of events leading to failure in software-controlled complex systems.Such systems are ubiquitous in all areas of everyday life,and safety and reliability analyses are increasingly required for these systems.SEFTs combine elements from the traditional fault tree with elements from state-based techniques.In the context of the real-time safety-critical systems,SEFTs do not describe the time properties and important timedependent system behaviors that can lead to system failures.Further,SEFTs lack the precise semantics required for formally modeling time behaviors.In this paper,we present a qualitative analysis method for SEFTs based on transformation from SEFT to timed automata(TA),and use the model checker UPPAAL to verify system requirements’properties.The combination of SEFT and TA is an important step towards an integrated design and verification process for real-time safety-critical systems.Finally,we present a case study of a powerboat autopilot system to confirm our method is viable and valid after achieving the verification goal step by step.展开更多
针对空间有效载荷系统高复杂性和高可靠性需求的特性,设计了一种基于SysML (System Modeling Language)的故障诊断方法.该方法融入MBSE (Model Based System Engineering)思想,提出了基于SysML的空间有效载荷系统故障分析流程.基于SysM...针对空间有效载荷系统高复杂性和高可靠性需求的特性,设计了一种基于SysML (System Modeling Language)的故障诊断方法.该方法融入MBSE (Model Based System Engineering)思想,提出了基于SysML的空间有效载荷系统故障分析流程.基于SysML对空间有效载荷系统建立了故障分析相关的模型,其中,为满足故障分析建模的需求,对SysML元模型进行扩展定义,从而实现对组件间关系和故障表征与直接关联组件间关系的描述;基于所建模型构建故障诊断的整体框架,并提供从SysML数字模型到FTA (Fault Tree Analysis)的转换逻辑,从而实现对所有故障可能性的获取.通过案例分析,对提出方法在实际应用中的具体流程进行分析,并验证了该方法的有效性和实用性.展开更多
基金supported by the National Natural Science Foundation of China(11832012)
文摘A state/event fault tree(SEFT)is a modeling technique for describing the causal chains of events leading to failure in software-controlled complex systems.Such systems are ubiquitous in all areas of everyday life,and safety and reliability analyses are increasingly required for these systems.SEFTs combine elements from the traditional fault tree with elements from state-based techniques.In the context of the real-time safety-critical systems,SEFTs do not describe the time properties and important timedependent system behaviors that can lead to system failures.Further,SEFTs lack the precise semantics required for formally modeling time behaviors.In this paper,we present a qualitative analysis method for SEFTs based on transformation from SEFT to timed automata(TA),and use the model checker UPPAAL to verify system requirements’properties.The combination of SEFT and TA is an important step towards an integrated design and verification process for real-time safety-critical systems.Finally,we present a case study of a powerboat autopilot system to confirm our method is viable and valid after achieving the verification goal step by step.
文摘目的洪水是影响尾矿库安全的重要因素,明晰洪水对尾矿库的风险传导路径有利于帮助识别关键风险因素,优化防控措施。方法结合文献计量法和专家决策筛选出尾矿库洪水风险的重要影响指标,利用解释结构模型(interpretative structural modeling,ISM)对指标层次进行划分,最后基于事故树分析(fault tree analysis,FTA)解析灾害的演化路径,并提出相应预防措施。结果结果表明:(1)基于文献计量法总共筛选出24个尾矿库洪水风险影响因素,结合平均权重值与专家经验确定10个相对重要的尾矿库洪水风险影响因素;(2)基于ISM计算得出10个影响因素和洪水风险间的相互影响关系,确定尾矿库洪水灾害的直接、间接和最根本影响因素;(3)结合ISM和事故案例,建立尾矿库洪水灾害事故树,通过布尔代数运算得出18种致灾路径和9种预防事故的路径;(4)分析事故树的结构重要度后发现对尾矿库洪水风险影响最大的事件是排洪能力不足、洪峰流量大和初始浸润线埋深浅。结论提出的文献计量法、ISM与FTA相结合的方法不仅实现了客观指标筛选与系统建模的融合,而且为尾矿库防洪实现从“被动应对”向“主动阻断”的转变提供了理论支撑。
文摘针对空间有效载荷系统高复杂性和高可靠性需求的特性,设计了一种基于SysML (System Modeling Language)的故障诊断方法.该方法融入MBSE (Model Based System Engineering)思想,提出了基于SysML的空间有效载荷系统故障分析流程.基于SysML对空间有效载荷系统建立了故障分析相关的模型,其中,为满足故障分析建模的需求,对SysML元模型进行扩展定义,从而实现对组件间关系和故障表征与直接关联组件间关系的描述;基于所建模型构建故障诊断的整体框架,并提供从SysML数字模型到FTA (Fault Tree Analysis)的转换逻辑,从而实现对所有故障可能性的获取.通过案例分析,对提出方法在实际应用中的具体流程进行分析,并验证了该方法的有效性和实用性.
文摘基于全球导航卫星系统GNSS(Global Navigation Satellite System)的列车定位单元具有覆盖范围广、定位精度高、维护成本低的特点,能满足现代铁路连续定位的性能要求,适合低密度线路的定位。本文设计基于GNSS的列车定位单元,针对系统性能中重要的两个参数的可靠性和安全性进行定性和定量计算。利用故障树分析方法,以定位单元无法完成定位功能为顶事件建立故障树进行分析。采用基于计算机的安全系统可靠性PDS方法,对定位单元的硬件安全完整性等级SIL(Safety Integrity Level)评价指标和每小时危险失效概率PFH(Probability of Failure per Hour)进行定量计算。实验结果显示:列车定位单元满足系统可靠性要求,各子系统板的安全性达到SIL2等级,经过功能验证实验,列车定位单元的实际定位误差小于2m,能够满足列车定位精度要求。
