事故树图形的计算机辅助绘制算法研究

提供了一种有效的算法,根据输入的各种事件的基本信息及其因果逻辑关系,利用树的深度优先遍历后序算法,实现事故树的自动绘制,体现事故树模型分析形象、直观、明了的特点.该算法能即时计算出事故树顶事件发生的概率、最小割集、概率重要度、关键重要度等参数,为对事故树进行定性、定量分析提供强有力的图形和数据支持.     

一种基于元数据的地质绘图系统数据管理设计

地质图形的绘制广泛应用于石油勘探开发、地质、农业、林业等领域，基于计算机辅助设计的地质图形绘制系统相对于传统的图版制图能极大的提高绘图效率和精度。用于地质绘图的地质数据类型复杂多变，如何利用计算机有效处理这些数据是图形绘制的关键。将元数据管理引入地质绘图系统，提出一种基于元数据的地质绘图系统数据管理设计方案，并以此为基础设计相应的地质绘图数据内存和文件管理方式，最终结合QT库高效实现跨平台的地质绘图系统。     

基于可视化的事故树分析系统研究与开发

事故树分析是安全系统工程最重要的分析方法之一，它能对各种系统的危险性进行辨识和评价，不仅能分析出事故的直接原因，而且能深入地揭示出事故的潜在原因。用它描述事故的因果关系直观、明了，思路清晰，逻辑性强，既可定性分析，又可定量分析。基于可视化理论和技术，建立了事故树可视化模型，确定了系统功能目标，完成了系统结构设计，构造了事故树图形生成与事故树动态分析于一体的集成分析环境，开发出事故树计算机分析系统，为事故分析和安全评价提供高效、准确的技术和方法。     

用胞变换法分析分段线性系统周期运动稳定性

本文首先简单介绍了胞变换法,并提出了加工绘图数据的一种算法,这种算法节省机时和存贮绘图数据所需的空间,使绘制各种吸引域图形成为可能。然后利用胞变换法对具有分段线性非线性特征的弹簧摇床的全局性态进行了分析研究,并用计算机模拟出该系统存在的各种周期运动的时间历程曲线及相应的周期运动的吸引域。论文分析了弹簧摇床五种阻尼参数下全局性态,得出了该类系统周期运动稳定性和阻尼之间的关系。     

运用事故树分析法辨识供电企业作业现场安全风险

运用风险管理理论，以供电企业作业现场人身触电事故为例，运用“事故树分析法”对作业现场可能存在的风险因素进行分析与辨识，根据安全风险的轻重缓急予以解决，实现供电企业安全生产。     

战争遗留爆炸物销毁事故分析

战争遗留爆炸物因性能不稳定、遗留点分散、数量大及种类多,其销毁作业事故常有发生。对此,应用安全系统工程中的事故树分析法,绘制了销毁事故树,分析了基本事件的结构重要度,得到了销毁事故的主要影响因素,提出了安全销毁战争遗留爆炸物必须"严格管理参与人员,科学使用专业器材,规范作业流程,严密组织实施"的措施。     

基于红黑树算法的VCR法爆破智能布孔

传统地下矿大直径深孔爆破设计采用Auto-CAD软件手工绘图,绘图过程复杂、方案修改繁琐,严重制约了矿山生产企业的高效发展。针对上述缺陷,提出一种智能的地下矿大直径深孔爆破设计布孔算法,该算法以红黑树算法为核心,通过软件导入矿体采矿模型,再对矿体模型网格化处理,生成设计炮孔,利用嵌入Map结构的红黑树算法链接所有炮孔,实现地下矿大直径深孔爆破设计。整个智能布孔设计借助DIMINE软件为平台,以冬瓜山铜矿为基础数据来源,比较本算法和传统手工算法实现下矿大直径深孔爆破智能布孔的时间。     

事故树分析方法(FTA)在大宗特气管理中的应用研究

初步介绍了事故树分析方法,将该方法应用于实际生产,找出了典型事故模式和重要安全隐患。     

CAD参数化自动绘图中解决图形不确定性的一种新方案

运用消隐的概念，处理计算机辅助设计中参数化自动绘制零件图所产生的图形不确定性。即用不透明的消隐平面，隐去由于不确定性而产生的多余图形。可在参数化绘图的程序编制中，省去对输入参数的判别归类的功能模块，对任何参数所对应的图形，实现单一化处理。从而简化了CAD系统的程序设计，提高了系统的灵活性、绘图效率和适应度。     

AutoCAD在机械制图设计中的应用

AutoCAD软件是美国Autodesk开发的一款计算机辅助绘图与设计应用型软件,它具有易于掌握、使用方便、体系结构开放等特点,机械制图设计人员能够使用它绘制各种二维图形与三维图形,并且它具有渲染图形与输出图纸等功能     

应用Petri网改进基于故障树的诊断方法

故障树是表示故障发生和故障传播关系的一种逻辑模型,基于故障树诊断方法的广泛应用由于实际故障树分析过程的ＮＰ困难问题而受到妨碍。而Ｐｅｔｉｒ网是一种特殊的有向网,适合于描述故障的传播关系。本文提出了两种基于Ｐｅｔｒｉ网的改进方法,与下行法相比,用该方法寻找最小割集和最小路集能有效地节省上计算时间,提高推理速度和效率;最后还应用Ｐｉｔｒｉ网的状态方程分析方法提出了基于Ｐｅｔｒｉ网的故障监测和诊断方法。     

基于Petri网和故障树的变电站故障诊断方法

针对变电站的设备组成及联接特点,利用Petri网(PN)的图形特性,提出了一种基于Petri网和故障树的变电站故障诊断模型和诊断方法.利用PN建立了可能性故障区域诊断模型,利用PN和故障树建立故障元件诊断模型.详细给出了变电站可能的故障区域诊断方法和变电站故障元件诊断方法.在故障元件的诊断中,建立了针对可能故障区域的面向设备的子Petri网模型,降低了诊断的复杂性.仿真研究表明,利用该方法可以比较容易实现变电站故障诊断系统,且有高的准确性和诊断效率.     

Risk Assessment of Railway Transportation Systems using Timed Fault Trees

Safety is an essential requirement for railway transportation. There are many methods that have been developed to predict, prevent, and mitigate accidents in this context. All of these methods have their own purpose and limitations. This paper presents a new useful analysis technique: timed fault tree analysis. This method extends traditional fault tree analysis with temporal events and fault characteristics. Timed fault trees (TFTs) can determine which faults need to be eliminated urgently, and it can also provide how much time have been left at least to eliminate the root failure to prevent accidents. They can also be used to determine the time taken for railway maintenance requirements, and thereby improve maintenance efficiency, and reduce risks. In this paper, we present the features and functionality of a railway transportation system, and principles and rules of TFTs. We demonstrate the applicability of our framework by a case study on a simple railway transportation system. Copyright © 2014 John Wiley & Sons, Ltd.     

基于模糊故障树的军用气象物资包装可靠性分析

应用模糊故障树分析方法对军用气象物资包装可靠性进行了系统分析,简要介绍了模糊故障树分析方法的基本理论,利用专家判断和模糊集理论相结合的方法,评估了故障树底事件发生的模糊失效概率。并以"TFS-1通风干湿表包装"为例,建立了包装系统的故障树,采用下行法求解了引起顶事件发生的最小割集,定量分析计算,得出模糊失效率为0.0705,同时计算了各底事件的重要度。模糊故障树分析方法对于提高军用气象物资包装防护能力,确保物资装备质量,具有非常重要的意义。     

An efficient real‐time method of analysis for non‐coherent fault trees

Fault tree analysis is commonly used to assess the reliability of potentially hazardous industrial systems. The type of logic is usually restricted to AND and OR gates, which makes the fault tree structure coherent. In non‐coherent structures not only components' failures but also components' working states contribute to the failure of the system. The qualitative and quantitative analyses of such fault trees can present additional difficulties when compared with the coherent versions. It is shown that the binary decision diagram (BDD) method can overcome some of the difficulties in the analysis of non‐coherent fault trees. This paper presents the conversion process of non‐coherent fault trees to BDDs. A fault tree is converted to a BDD that represents the system structure function (SFBDD). An SFBDD can then be used to quantify the system failure parameters but is not suitable for the qualitative analysis. Established methods, such as the meta‐products BDD method, the zero‐suppressed BDD (ZBDD) method and the labelled BDD (L‐BDD) method, require an additional BDD that contains all prime implicant sets. The process using some of the methods can be time consuming and is not very efficient. In addition, in real‐time applications the conversion process is less important and the requirement is to provide an efficient analysis. Recent uses of the BDD method are for real‐time system prognosis. In such situations as events happen, or failures occur, the prediction of mission success is updated and used in the decision‐making process. Both qualitative and quantitative assessments are required for the decision making. Under these conditions fast processing and small storage requirements are essential. Fast processing is a feature of the BDD method. It would be advantageous if a single BDD structure could be used for both the qualitative and quantitative analyses. Therefore, a new method, the ternary decision diagram (TDD) method, is presented in this paper, where a fault tree is converted to a TDD that allows both qualitative and quantitative analyses and no additional BDDs are required. The efficiency of the four methods is compared using an example fault tree library. Copyright © 2008 John Wiley & Sons, Ltd.     

Systematic evaluation of fault trees using real-time model checker UPPAAL

Fault tree analysis, the most widely used safety analysis technique in industry, is often applied manually. Although techniques such as cutset analysis or probabilistic analysis can be applied on the fault tree to derive further insights, they are inadequate in locating flaws when failure modes in fault tree nodes are incorrectly identified or when causal relationships among failure modes are inaccurately specified. In this paper, we demonstrate that model checking technique is a powerful tool that can formally validate the accuracy of fault trees. We used a real-time model checker UPPAAL because the system we used as the case study, nuclear power emergency shutdown software named Wolsong SDS2, has real-time requirements. By translating functional requirements written in SCR-style tabular notation into timed automata, two types of properties were verified: (1) if failure mode described in a fault tree node is consistent with the system's behavioral model; and (2) whether or not a fault tree node has been accurately decomposed. A group of domain engineers with detailed technical knowledge of Wolsong SDS2 and safety analysis techniques developed fault tree used in the case study. However, model checking technique detected subtle ambiguities present in the fault tree.     

An analytic solution for a fault tree with circular logics in which the systems are linearly interrelated

A circular logic or a logical loop is defined as the infinite circulation of supporting relations due to their mutual dependencies among the systems in the fault tree analysis. While many methods to break the circular logic have been developed and used in the fault tree quantification codes, the general solution for a circular logic is not generally known as yet. This paper presents an analytic solution for circular logics in which the systems are linearly interrelated with each other. To formulate the analytic solution, the relations among systems in the fault tree structure are described by the Boolean equations. The solution is, then, obtained from the successive substitutions of the Boolean equations, which is equivalent to the attaching processes of interrelated system's fault tree to a given fault tree. The solution for three interrelated systems and their independent fault tree structures are given as an example.     

A New Ordering Method of Basic Events in Fault Tree Analysis

The ordering of basic events is critical to fault tree analysis on the basis of binary decision diagrams (BDDs). Many attempts have been made to seek an efficient ordering result with the aim of reducing the complexity of BDD. In this article, a new ordering method, namely, priority ordering method, is proposed. The new method takes into account not only the effects of the layers of fault tree but also the repeated events, the neighboring events, and the number of events under the same gate. According to these four effects, the priorities that sort the basic events of the fault tree are defined. The new method inherits the merits of structure‐based and weight‐based methods. It is able to evaluate the basic events on the basis of the structure‐based method and the size of the subtree on the basis of the weighted‐based method. Demonstrated by the examples, the proposed priority ordering method is superior to the existing ordering methods in terms of reducing the nodes in the BDD and improving the efficiency in transforming a fault tree to a BDD. Copyright © 2011 John Wiley & Sons, Ltd.     

Computerized fault tree construction for a train braking system

A new approach for fault tree automation is proposed which is a hybrid of the digraph and decision table methods, using the best features of both. The new method is based on the flexibility of the decision table method but incorporates a way of detecting, classifying and analysing control loops, similar to the use of operators in the digraph approach. As well as using operators to deal with control loops, a new operator is introduced that deals with electrical circuits. This means that when constructing the fault trees, difficulties of handling repeated events are eliminated and the size of the fault trees is significantly reduced. The method has been tested by its application to a braking system on a train. © 1997 John Wiley & Sons, Ltd.     

Improved accuracy in quantitative fault tree analysis

The fault tree diagram defines the causes of the system failure mode or ‘top event’ in terms of the component failures and human errors, represented by basic events. By providing information which enables the basic event probability to be calculated, the fault tree can then be quantified to yield reliability parameters for the system. Fault tree quantification enables the probability of the top event to be calculated and in addition its failure rate and expected number of occurrences. Importance measures which signify the contribution each basic event makes to system failure can also be determined. Owing to the large number of failure combinations (minimal cut sets) which generally result from a fault tree study, it is not possible using conventional techniques to calculate these parameters exactly and approximations are required. The approximations usually rely on the basic events having a small likelihood of occurrence. When this condition is not met, it can result in large inaccuracies. These problems can be overcome by employing the binary decision diagram (BDD) approach. This method converts the fault tree diagram into a format which encodes Shannon's decomposition and allows the exact failure probability to be determined in a very efficient calculation procedure. This paper describes how the BDD method can be employed in fault tree quantification. © 1997 John Wiley & Sons, Ltd.