基于动态故障树的CTCS-3级ATP系统可靠性分析简

 针对传统的可靠性分析方法分析CTCS-3级ATP系统动态失效问题的不足,提出采用动态故障树分析其可靠性。首先,分析系统的结构和功能建立动态故障树模型;其次,采用深度优先最左遍历算法搜索动态故障树模型,得到独立的子树;最后,在引入可修系统可靠性指标基础上,采用解析法和马尔科夫矩阵迭代法求解子树,结合分层迭代方法对动态故障树分析法改进,以减小运算量,使得上述可靠性指标能用于CTCS-3级ATP系统的可靠性评估。计算所得可靠性指标与可靠性框图分析得到的结果对比表明：动态故障树能够更好地描述系统的冗余性和容错性等特点,提高了可靠性指标的精度。     

空分设备故障树分析

利用故障树分析（ＦＴＡ）法对国产某空分设备进行了可靠性分析，建立了空分设备的故障树。利用自编的故障树分析程序，对故障树进行定性和定量分析，获得了空分设备的可靠性参数和可靠性信息，为产品的可靠性设计和可靠性增长提供了依据。     

油田注汽锅炉运行可靠性研究

稠油开采不断出现了新技术、新设备,使得稠油产量和采收率不断提高。油田注汽锅炉是稠油开采中的关键设备,保证油田注汽锅炉的运行可靠性对保证稠油的产量至关重要。本文介绍了油田注汽锅炉的系统组成及特点,根据锅炉系统的结构和功能的层次分解模型,采用故障树分析法,建立注汽锅炉系统故障树和水处理系统的故障树,着重分析了水处理系统故障,为锅炉系统的故障诊断奠定了基础。     

电力继电保护系统可靠性的探究

随着电力系统规模的扩大,网络结构越来越复杂,电力系统可靠性问题受到越来越多的关注。电力系统其二次系统中继电保护的可靠性直接关系到电力系统的安全运行。文中分析了继电保护系统硬件和软件的失效因素,运用故障树分析法对电力继电保护系统可靠性进行分析,通过建立模型,并运用于具体算例,得出分析结果:运用故障树分析法对电力继电保护系统的可靠性进行分析是可行的。并且是准确的。     

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。     

一种六自由度上肢康复机器人的结构设计及运动学分析

为解决现有上肢康复机器人功能单一以及结构复杂的问题,提出了一种6-DOF外骨骼式上肢康复机器人,建立了康复机器人的运动学模型,通过D H变换对其正向运动学和逆向运动学进行求解.运用Pro/E对康复机器人进行三维建模,通过Mechanism/Pro导入ADAMS/view中进行运动学仿真,得到机器人末端位移的仿真曲线和理论曲线一致,验证了理论推导的正确性,进一步仿真结果证明该方案具有较好的运动特性.     

污水处理系统可靠性分析的研究

本文介绍了对污水处理系统进行可靠性分析的必要性,就目前国内、外污水处理现状以度存在的问题,提出了污水处理系统进行可靠性分析的方法。介绍了采用故障树分析法分析污水处理系统的关键性问题,例如：建树前准备、顶事件选择原则、建造原则及指南。指明采用故障树分析法分析污水处理系统可靠性的前景与发展方向。     

串联机器人单点定位精度可靠性研究

为评定机器人定位精度的可靠性，本文根据测量重复性和采样策略对机器人标定结果的影响，采用轴线测量法对六自由度串联机器人几何参数进行标定，应用蒙特卡洛算法对机器人末端单点定位精度的可靠性进行分析计算。结果表明：随着精度阈值增大，串联机器人定位精度的可靠度提升，应用蒙特卡洛算法，能对机器人定位精度可靠性进行准确评估。     

简析机械的可靠性设计

粗略介绍了有关机械可靠性的概念以及简单的分析方法。按照现代设计方法流程,通过故障树故障树分析、可靠性预测、参数设计、概率设计以及可靠性的函数尺度等方法对可靠性设计做了简单分析。通过分析表明,对机械进行可靠性设计分析有助于提高机械产品的使用寿命,更好的对机械产品做整体把握,从而提高经济效益。     

预应力钢筒混凝土管端口打磨机器人的压紧力可靠性分析

预应力钢筒混凝土管（prestressed concrete cylinder pipe,PCCP）在水利工程、工业供水等领域得到广泛应用。针对现有PCCP端口打磨方法效率低、打磨质量难以保证等问题,创新设计了一种PCCP承、插口打磨机器人。首先,根据工作服役环境要求,对端口打磨机器人进行了结构设计与样机制作,并通过现场试验分析该机器人的打滑失效问题;其次,根据打磨机器人克服摩擦力环绕承、插口作周向转动的打磨过程,在进行力学分析基础上建立其压紧力模型及可靠性模型,并采用随机摄动方法分析了整个打磨过程的动态可靠度,得到该打磨机器人可靠性最低的关键部位;最后,对影响端口打磨机器人可靠性的参数进行了灵敏度分析,得出使端口打磨机器人最快趋向可靠的参数为从动轮半径。研究结果为研发具有自主知识产权的大型PCCP自动化制造装备及进行下一步可靠性优化设计奠定了基础。     

Condition-based fault tree analysis (CBFTA): A new method for improved fault tree analysis (FTA), reliability and safety calculations

Condition-based maintenance methods have changed systems reliability in general and individual systems in particular. Yet, this change does not affect system reliability analysis. System fault tree analysis (FTA) is performed during the design phase. It uses components failure rates derived from available sources as handbooks, etc. Condition-based fault tree analysis (CBFTA) starts with the known FTA. Condition monitoring (CM) methods applied to systems (e.g. vibration analysis, oil analysis, electric current analysis, bearing CM, electric motor CM, and so forth) are used to determine updated failure rate values of sensitive components. The CBFTA method accepts updated failure rates and applies them to the FTA. The CBFTA recalculates periodically the top event (TE) failure rate (λ_TE) thus determining the probability of system failure and the probability of successful system operation—i.e. the system's reliability.FTA is a tool for enhancing system reliability during the design stages. But, it has disadvantages, mainly it does not relate to a specific system undergoing maintenance.CBFTA is tool for updating reliability values of a specific system and for calculating the residual life according to the system's monitored conditions. Using CBFTA, the original FTA is ameliorated to a practical tool for use during the system's field life phase, not just during system design phase.This paper describes the CBFTA method and its advantages are demonstrated by an example.     

Posbist fault tree analysis of coherent systems

When the failure probability of a system is extremely small or necessary statistical data from the system is scarce, it is very difficult or impossible to evaluate its reliability and safety with conventional fault tree analysis (FTA) techniques. New techniques are needed to predict and diagnose such a system's failures and evaluate its reliability and safety. In this paper, we first provide a concise overview of FTA. Then, based on the posbist reliability theory, event failure behavior is characterized in the context of possibility measures and the structure function of the posbist fault tree of a coherent system is defined. In addition, we define the AND operator and the OR operator based on the minimal cut of a posbist fault tree. Finally, a model of posbist fault tree analysis (posbist FTA) of coherent systems is presented. The use of the model for quantitative analysis is demonstrated with a real-life safety system.     

How dependent basic events with interval-valued probabilities affect fault tree analysis

This paper studies the effect of the dependence state between basic events (BEs) on fault tree analysis (FTA) when the probabilities of events are characterized by interval values. The well-known Frèchent bounds are extended for modeling six different types of dependence states between BEs. Three indices, called average dependence effect (ADE), location effect (LE) and size effect (SE), are defined for evaluating the effect of the dependence states between BEs on the probability of top event (TE) and identifying influential and non-influential dependence states. Then, the proposed method is applied to fault tree (FT) examples, thereby explaining the dependence problem in FTA. To further verify the practicability of the method, FTA of the unilateral asymmetric movement failure of an aircraft flap mechanism is performed. The results show that: (i) the opposite and negative dependence contribute to the reliability of a parallel system while the perfect and positive dependence reduce it, (ii) the perfect and positive dependence contribute to the reliability of a series system while the opposite and negative dependence reduce it, and (iii) parallel systems are more reliable than series systems regardless of the dependence between BEs.     

Hybrid fault tree analysis using fuzzy sets

In conventional fault tree analysis (FTA), the ambiguous and imprecise events such as human errors tend not to be handled effectively. To overcome this disadvantage, a hybrid approach employing fuzzy set evaluation and probabilistic estimation for FTA is proposed to evaluate abnormal events. The safety problem of unexpected robot motion in an aircraft wing drilling system was analyzed using the proposed method. The results indicated that the proposed approach is very effective in analyzing the reliability of a man-machine system.     

Application of FTA Method to Reliability Analysis of Vacuum Resin Shot Dosing Equipment

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基于FTA-FMMEA综合分析法的发动机曲柄连杆机构可靠性研究

为了提高发动机曲柄连杆机构的可靠度,采用FTA-FMMEA综合分析法对其进行分析。通过分析曲柄连杆机构各零件的故障,建立故障树模型,对其进行定性分析找出对系统影响较大的故障模式;对其中的活塞环磨损这一故障模式进行FMMEA分析,得到了其故障原因及故障机理,确定了其故障影响,并根据分析结果提出改进方案。改进前后的RPN值对比结果表明,FTA-FMMEA综合分析方法可以很好的分析系统故障并提高系统可靠性水平。     

Footprint of knowledge acquisition improvement in failure diagnosis analysis

Fault tree analysis (FTA) as an effective and efficient risk assessment tool are widely used to analyze the reliability of a complex system. In this context, FTA can properly improve the safety performance of the system by preventing an event which may lead to occurrence of a catastrophic accident. However, traditional FTA is still suffering from dynamic structure demonstration and importantly epistemic uncertainty processing. In this study, a novel methodology is introduced using Bayesian updating mechanism to deal with dynamic structure and 2‐tuple fuzzy set named as intuitionistic fuzzy numbers are employed to cope with subjectivity of uncertainty processing. Accordingly, the most critical system components which affect the system reliability are recognized by using an appropriate sensitivity analysis method. The proposed methodology is then applied on a real case study application (a brake fluid filling system) in order to examine the effectiveness and feasibility of the approach. The results illustrated that the new methodology can have enough benefits for diagnosing the systems' faults compared with listing approaches of safety and reliability analysis. In terms of empirical case study, “electromotor failure” was evaluated as the second most critical basic event in conventional‐based approaches, whereas in the novel methodology “high pressure liquefied material” was recognized as the second one.     

机器人的运动时变可靠性分析

机器人系统存在的多种不确定性会导致其运动精度下降,为此开展机器人运动时变不确定性建模与分析,以期提高机器人运动精度。首先基于运动学分析建立了机器人末端执行器参考点位姿误差模型,随后基于机器人位姿误差模型提出了末端执行器位置精度的点（静态）可靠性、时变（区间）可靠性模型以及机器人运动的系统可靠性模型,最后给出了实现上述可靠性模型高效、高精度求解的包络方法,并以斯坦福机器人为实例验证了所提模型和求解方法的有效性。研究表明,所提出的可靠性模型能够有效获得机器人各坐标分量上的时变可靠度以及机器人运动的系统可靠度。研究工作为提高机器人运动精度提供了新方法。     

FMECA and FTA Methods of Reliability Analysis for Oil and Gas Pipeline Robot

In this paper,FMECA and FTA methods are presented for oil and gas Pipeline Robot in order to improve the reliability.Take a crawler pipeline cleaning robot as t...