The crashworthiness is an important design factor of civil aircraft related with the safety of occupant during impact accident. It is a highly nonlinear transient dynamic problem and may be greatly influenced by the u...The crashworthiness is an important design factor of civil aircraft related with the safety of occupant during impact accident. It is a highly nonlinear transient dynamic problem and may be greatly influenced by the uncertainty factors. Crashworthiness uncertainty analysis is conducted to investigate the effects of initial conditions, structural dimensions and material properties. Simplified finite element model is built based on the geometrical model and basic physics phenomenon. Box-Behnken sampling and response surface methods are adopted to obtain gradient information. Results show that the proposed methods are effective for crashworthiness uncertainty analysis. Yield stress, frame thickness, impact velocity and angle have great influence on the failure behavior, and yield stress and frame thickness dominate the uncertainty of internal energy. Failure strain and tangent modulus have the smallest influence on the initial peak acceleration, and gradients of mean acceleration increase because the appearance of material plastic deformation and element failure.展开更多
We consider reliability engineering in modern civil aviation industry, and the related engineering activities and methods. We consider reliability in a broad sense, referring to other system characteristics that are r...We consider reliability engineering in modern civil aviation industry, and the related engineering activities and methods. We consider reliability in a broad sense, referring to other system characteristics that are related to it, like availability, maintainability, safety and durability. We covered the entire lifecycle of the equipment, including reliability requirement identification, reliability analysis and design, verification and validation of reliability requirements(typically involved in the equipment design and development phase), quality assurance(which typically enters in the manufacturing phase), and fault diagnosis and prognosis and maintenance(which are connected to the operation phase). Lessons learnt from reliability engineering practices in civil aviation industry are given, which might serve as reference for reliability managers and engineers, also from other industries with high reliability requirements.展开更多
安全是民航业的核心主题。针对目前民航非计划事件分析严重依赖专家经验及分析效率低下的问题,文章提出一种结合Word2vec和双向长短期记忆(bidirectional long short-term memory,BiLSTM)神经网络模型的民航非计划事件分析方法。首先采...安全是民航业的核心主题。针对目前民航非计划事件分析严重依赖专家经验及分析效率低下的问题,文章提出一种结合Word2vec和双向长短期记忆(bidirectional long short-term memory,BiLSTM)神经网络模型的民航非计划事件分析方法。首先采用Word2vec模型针对事件文本语料进行词向量训练,缩小空间向量维度;然后通过BiLSTM模型自动提取特征,获取事件文本的完整序列信息和上下文特征向量;最后采用softmax函数对民航非计划事件进行分类。实验结果表明,所提出的方法分类效果更好,能达到更优的准确率和F 1值,对不平衡数据样本同样具有较稳定的分类性能,证明了该方法在民航非计划事件分析上的适用性和有效性。展开更多
面对日益复杂的飞机系统,传统的安全性分析方法对复杂系统间的不安全交互行为和危险源的识别能力不足。为有效评价持续适航阶段的飞机系统安全性,提出了一种融合系统理论过程分析(system theory process analysis,STPA)和动态故障树(dyn...面对日益复杂的飞机系统,传统的安全性分析方法对复杂系统间的不安全交互行为和危险源的识别能力不足。为有效评价持续适航阶段的飞机系统安全性,提出了一种融合系统理论过程分析(system theory process analysis,STPA)和动态故障树(dynamic fault tree,DFT)的改进的STPA安全性分析方法和评价模型。模型采用STPA识别出不安全控制行为和致因因素,并将其与动态故障树分析方法相融合,以事故致因理论优化致因分析方法,计算得出不安全控制行为发生概率并确定系统潜在危险的关键致因因素。以飞机起落架系统为例进行分析验证,结果表明,改进后的STPA分析方法可以准确地对系统危险进行识别和分析,为持续适航阶段的安全性分析提供支持。展开更多
平视显示(Head-up Display,HUD)系统属于航电安全关键系统,可以提高低能见度下的飞机运行安全,需要在系统研制过程中开展完善的风险识别与分析。随着系统复杂性的增加,传统方法很难捕获系统组件交互带来的危险。为此,采用系统理论过程分...平视显示(Head-up Display,HUD)系统属于航电安全关键系统,可以提高低能见度下的飞机运行安全,需要在系统研制过程中开展完善的风险识别与分析。随着系统复杂性的增加,传统方法很难捕获系统组件交互带来的危险。为此,采用系统理论过程分析(Systematic Theory Process Analysis,STPA)对HUD进行分析,充分考虑系统的多方交互,识别系统潜在的不安全控制行为,同时利用时间自动机理论及其工具UPPAAL对系统进行建模,验证STPA识别的不安全控制行为;最后设计了一个路径算法,对导致其发生的危险路径进行检索。结果表明,该方法能够识别出系统潜在的危险及其原因,减少了人为因素对分析的影响。展开更多
基金supported by the Postdoctoral Science Foundation of China (Nos. 2012M510306, 2013T60054)
文摘The crashworthiness is an important design factor of civil aircraft related with the safety of occupant during impact accident. It is a highly nonlinear transient dynamic problem and may be greatly influenced by the uncertainty factors. Crashworthiness uncertainty analysis is conducted to investigate the effects of initial conditions, structural dimensions and material properties. Simplified finite element model is built based on the geometrical model and basic physics phenomenon. Box-Behnken sampling and response surface methods are adopted to obtain gradient information. Results show that the proposed methods are effective for crashworthiness uncertainty analysis. Yield stress, frame thickness, impact velocity and angle have great influence on the failure behavior, and yield stress and frame thickness dominate the uncertainty of internal energy. Failure strain and tangent modulus have the smallest influence on the initial peak acceleration, and gradients of mean acceleration increase because the appearance of material plastic deformation and element failure.
基金supported by the National Natural Science Foundation of China (Nos. 61573043, 71671009 and 71601010)
文摘We consider reliability engineering in modern civil aviation industry, and the related engineering activities and methods. We consider reliability in a broad sense, referring to other system characteristics that are related to it, like availability, maintainability, safety and durability. We covered the entire lifecycle of the equipment, including reliability requirement identification, reliability analysis and design, verification and validation of reliability requirements(typically involved in the equipment design and development phase), quality assurance(which typically enters in the manufacturing phase), and fault diagnosis and prognosis and maintenance(which are connected to the operation phase). Lessons learnt from reliability engineering practices in civil aviation industry are given, which might serve as reference for reliability managers and engineers, also from other industries with high reliability requirements.
文摘安全是民航业的核心主题。针对目前民航非计划事件分析严重依赖专家经验及分析效率低下的问题,文章提出一种结合Word2vec和双向长短期记忆(bidirectional long short-term memory,BiLSTM)神经网络模型的民航非计划事件分析方法。首先采用Word2vec模型针对事件文本语料进行词向量训练,缩小空间向量维度;然后通过BiLSTM模型自动提取特征,获取事件文本的完整序列信息和上下文特征向量;最后采用softmax函数对民航非计划事件进行分类。实验结果表明,所提出的方法分类效果更好,能达到更优的准确率和F 1值,对不平衡数据样本同样具有较稳定的分类性能,证明了该方法在民航非计划事件分析上的适用性和有效性。
文摘面对日益复杂的飞机系统,传统的安全性分析方法对复杂系统间的不安全交互行为和危险源的识别能力不足。为有效评价持续适航阶段的飞机系统安全性,提出了一种融合系统理论过程分析(system theory process analysis,STPA)和动态故障树(dynamic fault tree,DFT)的改进的STPA安全性分析方法和评价模型。模型采用STPA识别出不安全控制行为和致因因素,并将其与动态故障树分析方法相融合,以事故致因理论优化致因分析方法,计算得出不安全控制行为发生概率并确定系统潜在危险的关键致因因素。以飞机起落架系统为例进行分析验证,结果表明,改进后的STPA分析方法可以准确地对系统危险进行识别和分析,为持续适航阶段的安全性分析提供支持。
文摘平视显示(Head-up Display,HUD)系统属于航电安全关键系统,可以提高低能见度下的飞机运行安全,需要在系统研制过程中开展完善的风险识别与分析。随着系统复杂性的增加,传统方法很难捕获系统组件交互带来的危险。为此,采用系统理论过程分析(Systematic Theory Process Analysis,STPA)对HUD进行分析,充分考虑系统的多方交互,识别系统潜在的不安全控制行为,同时利用时间自动机理论及其工具UPPAAL对系统进行建模,验证STPA识别的不安全控制行为;最后设计了一个路径算法,对导致其发生的危险路径进行检索。结果表明,该方法能够识别出系统潜在的危险及其原因,减少了人为因素对分析的影响。
