Risk Assessment Based on Fault Tree Analysis for Damaged Pipe Repair During Operation in Petrochemical Plant

In petrochemical plant, the in-operation repairing is usually a repairing strategy with pressured inoperation repairing for avoiding huge economic losses caused by unplanned shutdown when some slight local leakage happens in pipes. This paper studies the effects of repairing strategies on the failure probability of the pipe systems in process industries based on the time-average fault tree approach, especially the in-operation repairing strategies including pressured in-operation repairing activities. The fault tree model can predict the effect of different repairing plans on the pipe failure probability, which is significant to the optimization of the repairing plans. At first pipes are distinguished into four states in this model, i.e., successive state, flaw state, leakage state and failure state. Then the fault tree approach, which is usually applied in the studies of dynamic equipment, is adopted to model the pipe failure. Moreover, the effect of pressured in-operation repairing is also considered in the model. In addition, this paper proposes a series of time-average parameters of the fault tree model, all of which are used to calculate node parameters of the fault tree model. At last, a practical case is calculated based on the fault tree model in a repairing activity of pipe thinning.

FAULT TREE ANALYSIS OF SPONTANEOUS COMBUSTION OF SULPHIDE ORES AND ITS RISK ASSESSMENT

A logic fault tree of mine spontaneous combustion of sulphide ores was built by the fault tree analysis (FTA) based on a lot of mechanism investigation of sulphide ore spontaneous combustion in more than ten mines and review of a great amount of relevant

Network security equipment evaluation based on attack tree with risk fusion

Network security equipment is crucial to information systems, and a proper evaluation model can ensure the quality of network security equipment. However, there is only a few models of comprehensive models nowadays. An index system for network security equipment was established and a model based on attack tree with risk fusion was proposed to obtain the score of qualitative indices. The proposed model implements attack tree model and controlled interval and memory(CIM) model to solve the problem of quantifying qualitative indices, and thus improves the accuracy of the evaluation.

基于关联分析FP-Tree算法的企业风险信息数据在线挖掘方法

现阶段的数据挖掘方法缺少对数据关联分析的过程,挖掘效果较差,故文章提出基于关联分析频繁模式树(FrequentPattern Tree, FP-Tree)算法的企业风险信息数据在线挖掘方法。选取与企业风险相关的信息指标,收集有关数据并进行预处理操作后,设计一种考虑关联分析的FP-Tree算法,生成FP-Tree节点的条件模式树挖掘频繁项集,计算满足最小置信度的频繁项集,实现企业风险信息数据在线挖掘。实验结果表明,所用方法挖掘量和挖掘效率较高。

Fault Tree+软件在长输天然气管道定量风险分析中的应用

为了确定影响长输天然气管道系统发生事故的各种因素,减少事故发生所造成的损失,保证管道安全运行,借助Fault Tree+软件对天然气管道系统进行了定量风险分析。根据相关资料,建立了长输天然气管道系统的故障树,明确了44个基本事件的概率,并运用Fault Tree+软件分析、计算功能,确定了管道穿孔、断裂等中间事件以及管道失效顶事件的概率。再以"断裂泄漏"事故开展事件树分析,建立"立即点燃"、"延迟点燃"等事件,并推导了可能导致的所有后果及概率,计算出"延迟点燃"事件没有发生以及发生"爆炸"事故的概率。最后以经济损失来度量"断裂泄漏"各后果事件的失效风险,累加每个后果事件的经济损失,得到某段天然气管道"断裂泄漏"事故的风险值。

农村自建房安全风险识别与评估研究

该文采用风险评估理论对农村自建房安全风险进行了识别与评估,通过对2013年至2022年间97起倒塌事故的统计分析,总结出导致非自然灾害下房屋倒塌的主要危险因素,包括不合格建材、地基处理不当、设计不合理、施工质量问题、施工超载、违规操作、承重墙拆除、无资质施工队伍和缺乏监管等。采用故障树分析法构建了风险评估模型,并通过基本事件重要度计算识别关键倒塌因素,进而对评估指标体系进行了实例验证。研究提出了针对性的风险管理建议,以提升农村自建房的安全水平。

Application of decision tree to selection of MTBM for adverse geological conditions

So many potential risks can be identifed for application of trenchless technology especially using microtunneling methods.Unexpected changes in ground conditions,such as encountering boulders,tree roots,ground water and man-made structures such as old foundations are the principal geotechnical risks,which affect the selection of an appropriate microtunnel boring machine.On the other hand,the performance of each microtunneling technique will differ while encountering such conditions.Hence,predicting the potential hazards provides a better safety and risk management plan.In this study,a couple of potentially hazardous situation,which are commonly associated with ground conditions,were identifed and investigated.A decision tree aid methodology was proposed based on geotechnical risk assessment for selection of proper microtunneling technique.Based on the approach the most appropriate microtunneling technique has the minimum risk level either before or after hazards mitigation measures.In order to check the effciency of the approach in practice,selection of microtunnel boring machine for Hamadan sewerage pipeline project was evaluated.Accordingly,an earth pressure balance(EPB)MTBM was selected for the project.

Reliability Risk Evaluation Method for Complex Mechanical System Based on Optimal Bayesian Network

In order to reduce the calculation of the failure probability in the complex mechanical system reliability risk evaluation,and to implement importance analysis of system components effectively,the system fault tree was converted into five different Bayesian network models. The Bayesian network with the minimum conditional probability table specification and the highest computation efficiency was selected as the optimal network. The two heuristics were used to optimize the Bayesian network. The fault diagnosis and causal reasoning of the system were implemented by using the selected Bayesian network. The calculation methods of Fussel-Vesely( FV),risk reduction worth( RRW),Birnbaum measure( BM) and risk achievement worth( RAW) importances were presented. A certain engine was taken as an application example to illustrate the proposed method. The results show that not only the correlation of the relevant variables in the system can be accurately expressed and the calculation complexity can be reduced,but also the relatively weak link in the system can be located accurately.

Structure and species composition of tree stands on verges and slopes along a major highway in Hong Kong

Arboricultural research focusing on transport land use was lacking in Hong Kong.Some highway slopes were registered in the Systematic Identification of Maintenance Responsibility of Slopes in the Territory(SIMAR),abbreviated as SIMAR slopes.We aimed to analyze patterns in the structure and species composition of the tree stock along a highway in Hong Kong and examined how a slope registration system could help explain the characteristics of urban forests.The 53 slopes and 52 verges along San Tin Highway,Hong Kong were randomly selected.The trees on each slope and verge were collectively sampled as a tree stand.Six variables,namely tree abundance,species richness,maximum tree height,Shannon-Wiener diversity,Simpson's dominance,and Pielou's evenness were measured for each stand.In addition,a limited visual tree risk assessment was performed.The 7,209 trees in 23 species were recorded.Species richness was low,ranging from one to eight species per stand.SIMAR and non-SIMAR slopes were compared.SIMAR slopes had significantly higher species richness,diversity,evenness but lower dominance,with mean difference of 1.41 species,0.17,0.17 and-0.28respectively.SIMAR slopes were associated with lower tree risk rating.When training regression models,boosting as an ensemble method arbitrarily raised the explanatory power and the predictive accuracy of some models.Slope height,length,angle and area could be significant predictors of the biodiversity-related variables.Future research can sample more habitat characteristics related to the structure and species composition of slopes and verges which were important components of urban forestry.

Comparing rockfall hazard and risk assessment procedures along roads for different planning purposes

Hazard and risk assessment procedures of different types of rockfall were analyzed to compare their outcomes when they are applied to the same case study.Although numerous methodologies are available in literature,rockfall hazard and risk analyses are often limited to standard estimations,affected by a margin of uncertainty,especially when relevant engineering projects are about to be realized.Based on the design purpose,different types of approaches can be chosen among the qualitative and quantitative ones available in literature,which allow different levels of analysis.One of the main criticisms related to rockfall events is the risk affecting linear structures,such as road or railways,due both to their strategic relevance for trade and communications and to the great entity of the exposed value(traffic units)traveling along them.In this perspective,a comparison between the qualitative method known as Evolving Rockfall Hazard Assessment(EHRA),the semi-quantitative modified Rockfall Hazard Rating System(RHRS)and the quantitative Rockfall Risk Management(RoMa)approach is herein commented according to a practical application to a case study.It is the case of the rockfall threat along slopes crossed by a strategic road connecting two of the most known spots of eastern Sicily(Italy),at the Taormina tourist complex.Data were retrieved from both recent literature and technical surveys on field.Achieved results highlight how the approaches are affected by a different level of detail and uncertainty,arising also by some necessary assumption that must be taken into account,especially when mitigation measures or territory planning have to be designed.Achieved results can be also taken into account for similar studies worldwide,in order to choose the most suitable procedure based on the design purpose.This is indeed crucial in the perspective of the optimization of time and economic resources in the territorial planning practice.

基于多模态超声建构胎儿先天性心脏病决策树模型及其应用价值

目的:分析基于多模态超声建构胎儿先天性心脏病决策树模型及其应用价值。方法:随机选取2021年4月-2023年7月在本院产前超声检查孕中期孕妇300例,常规产科超声检查确定胎儿生长程度,核实孕周,采用超声多断面模式方法对胎儿心脏进行多断面检测,包括四腔心断面、三血管断面、主动脉弓断面、左室流出道断面、右室流出道断面。对正常分娩的新生儿进行心脏多断面超声检测。对300例胎儿进行多断面模式超声检测,分析胎儿是否伴有先天性心脏畸形,对比超声检查与随访结果符合情况。结果:超声检出21例先天性心脏畸形胎儿,8例选择引产,余13例正常分娩。超声诊断与随访结果对比,卵圆孔直径增大、法洛四联症、完全型心内膜垫缺损、二尖瓣闭锁、右室发育不良综合征、左室发育不良综合征、大动脉转位、永存动脉干、单心室、三尖瓣下移符合率均为100%,超声诊断室间隔缺损7例,随访发现室间隔诊断5例,诊断符合率71.4%。279例超声诊断无先天性心脏畸形胎儿出生后经超声诊断发现有1例卵圆孔未闭、3例室间隔缺损,共4例漏诊患儿,漏诊率0.54%。四腔心断面、三血管断面、主动脉弓断面、左室流出道断面、右室流出道断面诊断胎儿畸形率分别为3.95%、0.63%、2.76%、3.27%、3.25%。由决策树模型可得,产前超声检查发现胎儿心脏可疑异常、高龄孕妇、孕妇接受药物治疗或射线暴露、孕妇有先天性心脏病家族史是胎儿存在先天性心脏病的独立危险因素,其中产前超声检查发现胎儿心脏可疑异常的影响最为显著。结论:孕中期胎儿产前超声多断面模式筛查胎儿先天性心脏病,能够对多数胎儿先天性心脏病进行诊断。

Fuzzy Risk Assessment Model of Power Transformer Based on Borda Number Theory

The power transformer is the key equipment of transforming voltage and exchanging power in the power system.It's safe and reliable operation directly influences the safe level of the power system.To study the risk assessment of power transformer which is very significant to improve the reliability of the power system,a fuzzy comprehensive risk assessment model of power transformer based on Borda number theory is proposed in this paper.At first,the fault types and risk factors of the power transformer are analyzed.Secondly,the basic framework of the fuzzy comprehensive evaluation is applied to quantify the risk factors.And then,Borda number theory is employed to analyze influence degree and occurrence probability of power transformer.At last,the various risk factors impact index and fuzzy comprehensive evaluation index of power transformer can be easily obtained.Applying this model,the relative importance degree of the risk factors can be horizontally compared according to the numerical index,the engineering staff can directly get the parameters of the transformer risk level and get a good description of the visual expression through using 5 score and similar visual language.

基于改进模糊故障树法的梯级水电站联合运行期风险分析

以我国某大型梯级水电站为例,基于文献分析法识别其联合运行期的风险源,建立风险指标体系,对传统的模糊故障树法进行改进,在其量化风险概率的基础上,利用层次分析法确定基本事件重要性权重,二者相结合对梯级水电站联合运行期进行风险分析,计算出梯级水电站联合运行期的风险发生概率。结果表明,梯级水电站联合运行期的风险发生概率为4.22×10^(-3),根据《水电站大坝运行安全评价导则》综合判定,风险等级较高,应合理制定相应措施加强风险防范,降低风险损失。研究结果为制定梯级水电站风险防控措施以及进行风险管理提供了基础和支持。

Assessment of Industrial Risks Related to Steam Production in a Thermal Production Service: Case of the Ouaga North of Burkina Faso Thermal Production Service

In this work, we have focused on the risks emanating from the steam production process in a thermal production department with a view to reducing the occurrence of unwanted events. The practical aspect of this study is to ensure the well-being of production actors and the surrounding population. Subsequently, we opted for fault tree analysis and HAZOP, which are tools for studying the probabilities of occurrence of unwanted events in the operation of industrial thermal installations. In addition, in the process of steam production, it emerges that pressure and temperature remain the most important parameters to monitor in order to reduce the risks associated with chemicals but especially with steam circuits.

故障树和模糊贝叶斯网络在管廊运维风险评估中的应用研究

地下综合管廊是城市的生命线,一旦出现问题就会对人们生命财产安全造成巨大损害。为了系统地分析管廊运维风险,建立了基于模糊贝叶斯网络的风险评估框架。首先,通过分析管廊运维风险源与风险形成的原因以确定风险事件和风险类别;其次,建立管廊运维风险故障树来梳理风险因素之间的逻辑关系,将故障树映射为贝叶斯网络;最后,结合专家模糊评价,构建地下综合管廊运维风险评估模型。案例分析结果显示:中间事件“火灾、爆炸”与“危害气体浓度过高”的发生概率较高。敏感性分析结果显示:“运维人员操作和维护不当”是导致管廊运维风险发生的根本事件,因此需要制定严格管理措施及规范,加强对运维人员的素质培训,以降低管廊运维过程中各种风险的发生概率。

因天气影响的航空器绕飞管制安全评估及策略分析

为降低航空器在绕飞情况下管制指挥事故的风险,采用事故树分析法(fault tree analysis, FTA)和层次分析法(analytic hierarchy process, AHP)相结合的方式对管制员在进行绕飞管制时发生指挥事故建立综合风险评估模型并制定风险管控措施,以及验证所提管控措施的有效性。首先对各风险因素进行逐层分析,找出其关联性,建立绕飞管制指挥事故的事故树模型。以此为基础,结合层次分析法,确定各层风险指标权重。同时依据各指标总权重的排序结果,提出了在绕飞情况下管制指挥事故的管控措施,最后以长沙区域管制空域为实例对所提方案进行验证。结果表明:在本文方案下虽然雷雨、风切变、协调程序过于复杂和航空器偏离计划航路仍然是导致绕飞管制事故的重要因素,但其重要程度下降了6.2%,且成熟管制员人数不足、扇区流量大和预案频繁发生变化的状况得到有效解决。证明了该方案能够有效抑制导致绕飞管制指挥事故发生的事件的重要程度,减少因极端天气和扇区负荷过大而出现的安全风险事故,整体提高管制系统的稳定性和可靠性。

人工智能在图书馆的应用及风险防范

在信息技术快速发展的背景下,人工智能技术已广泛应用于图书馆,极大地提升了管理效率和服务质量,同时也带来了复杂多变的安全风险。如何应对图书馆智能化过程中可能出现的安全威胁,成为一个亟待解决的问题。在分析人工智能理论及其在图书馆的应用和人工智能技术驱动的图书馆场景化服务体系架构的基础上,探讨了人工智能引发的安全威胁及其成因,并通过机器学习技术构建图书馆智能安全防御系统,利用决策树和随机森林方法,建立一种图书馆智能化安全防御模型,旨在为人工智能在图书馆的有效应用提供一定的理论参考。

古树断裂倒伏风险评估原理与防护设计

强度缺陷和风雪荷载是导致古树断裂倒伏的两大因素。古树的风险评估就是通过望诊、检测、探根及测绘,找出安全隐患、确定缺陷位置及大小、分析古树受力破坏方式、测算剩余强度和稳定性,而古树的安全防护就是设计安装必要的支撑与拉纤来防止这种破坏发生。本文阐述了古树风险评估的原理和方法,并介绍了不同类型支撑与拉纤的设计和应用。

古树名木雷电灾害风险性分析

文章利用安徽省2010—2022年闪电定位监测数据及马鞍山市1956—2014雷暴日资料,运用雷电风险理论,构建了古树名木雷击风险计算模型,经计算得出结论:雷击银杏树产生的人身伤亡损失风险较大、自然文化遗产损失风险较小。银杏树遭受雷击物理受损的概率较低,但有雷雨天气发生时,在树下躲避的人身安全风险较大,可采用警示标语提醒、雷电预警及在通道下铺设沥青等方法防范雷电事故,以期研究结果能为国内古树名木的防雷工作提供借鉴。

车用加氢站火灾爆炸事故风险分析

目的完善氢能产业链基础设施,寻求车用加氢站火灾爆炸事故致因,提出车用加氢站火灾爆炸事故防控措施,保障其安全可持续发展,提高大众对车用加氢站安全防控的信任度。方法采用事故致因理论揭示事故发生的本质,从能量物质、能量载体以及物的不安全状态和人的不安全行为角度出发,系统性地分析车用加氢站火灾爆炸事故的危险源,并以其火灾爆炸事故为顶上事件建立事故树图,提出有针对性的防控策略。结果①车用加氢站火灾爆炸属于物的不安全状态的基本事件占比最大,为52%;②可能引发车用加氢站火灾爆炸的最小割集有350个,避免火灾爆炸事故发生的最小经集有4个;③不考虑基本事件发生的概率,通风不良、报警装置故障、检测器失效、安全阀故障和自动制动系统故障5个基本事件的结构重要度最大。结论事故致因理论能科学全面地对车用加氢站进行危险源辨识,事故树系统分析了其基本事件结构重要度,保护措施正常运行是削减其火灾爆炸事故的关键控制点,给车用加氢站建站管理等制定相关防控措施提供了理论依据。