Using an expanded Safety Failure Event Network to analyze railway dangerous goods transportation system risk-accident

In order to improve the reliability and safety of railway dangerous goods transportation system (RDGTS), and prevent the similar accidents happened again, an easier operated, dynamic, systemic and quantitative approach called expanded Safety Failure Event Network (SFEN) is proposed to analyze the past typical RDGTS accidents. The expanded SFEN focuses on transfer the traditional safety occurrence process into a visible Accident Analysis Network (AAN) platform. To improve the previous SFEN approach, the risk factors categories are expanded including Human actions, Technical failure, Nature of transported goods, Environment factors, Management failure and External factors of the system. An AAN is established by using the risk factors as the nodes and using the interactions among these risk factors as the edges, the RDGTS risk analysis problem is transferred into a quantitative network structure analysis problem from a network perspective. After that, based on the AAN, TouchGraph and NetMiner are applied to calculate and rank the centrality degree of each sub-risk factor (or sub-heading) in a network. A RDGTS accident happened in 2001 is analyzed, the results show that TouchGraph and NetMiner can present the same interactions and importance of sub-risk factors (or sub-headings) through visible circle images in the platform, NetMiner is more digital because the results can be presented as the centrality degree values. The greatest contributed sub-risk factors are Equipment maintenance failure and Railway inspection agency failure, followed by cargo packaging problems, illegal entrainment problem. Misbehaves of the freight inspector with centrality degree 0.523810 shows that this sub-heading has the greatest contribution to the accident.     

Reliability and availability modeling of Subsea Xmas tree system using Dynamic Bayesian network with different maintenance methods

Subsea Xmas tree is a vital equipment for offshore oil and gas development. Aiming at the fault mode of subsea Christmas tree system under production conditions, the fault tree of subsea tree system was established, which was transformed into Dynamic Bayesian network, and the reliability and availability of subsea tree system with different repair states are quantitatively analyzed. In this paper, the DBNs are partially verified by the method based on three axes. The results show that the reliability of subsea vertical tree system is slightly higher than that of subsea horizontal tree system. After repair and maintenance, the performance of subsea tree system has been significantly improved, and the improvement of the system performance by preventive maintenance is more obvious. Compared with the perfect repair, the performance of the system with imperfect repair is not significantly reduced. Compared with perfect repair & preventive maintenance, the performance of the system with imperfect repair & preventive maintenance is slightly reduced. In addition, the influence of failure rates and degradation probability on reliability and availability is analyzed. By comparing the influence of failure rates on the system performance of non-maintenance and maintenance, it is found that the change of failure rates has the greatest influence on the reliability and the least influence on the availability of perfect repair & preventive maintenance. By comparing the performance of each component in the subsea tree system, it is found that the failure rates has the most obvious influence on the chock module, and gate valve and tree cap have the most significant influence on the reliability of the system. In order to improve the reliability of subsea tree system, it is necessary to improve the reliability of chock module, gate valve and tree cap.     

机电产品可靠性研究与探讨

机电产品越来越广泛地应用于社会各个领域,随着自动化、小型化程度的提高,很多机电产品结构越来越复杂,并且其使用条件也越来越严酷,由此产生的产品可靠性问题必然越来越多,可靠性技术也越来越受到重视。本文针对机电产品,从可靠性管理、可靠性设计和分析、可靠性试验和评定三个方面,对可靠性研究工作进行初步探讨。     

Information seeking in documents by pilots: Assessment of the reliability problems caused by the transition from paper to electronic

Information seeking is completely ignored in research on aviation psychology and more generally in issues of air transport safety. But information seeking occupies a central place in the pilots’ work. And this activity is undergoing an important development: the transition from paper to electronic documents. A contribution to the assessment of this transition is presented here. The assessment is focused on deterioration of information access, understanding and exploitation, and their possible negative consequences in terms of reliability. The exploitation of the documentation by pilots, and particularly the information seeking activity, are described and linked to their contexts (i.e. the main tasks of flying that require information seeking). Then an users test is presented where some information-seeking tasks are evaluated in terms of cost and errors, by comparing electronic and paper documents. The results show that electronic documents provide new functions that seem useful but also that too many new functions generate difficulties. Then it seems that pilots need some time to learn how to use these new documents. Reducing attention needed to perform a task such as calculation is risky. Some aspects of information seeking by the pilots should be better analysed and evaluated.     

库仑滴定法测定化学需氧量的可靠性研究

通过对库仑滴定法测定废水中化学需氧量存在的问题分析,提出相应解决办法,加强空白值式剂,器皿使用过程中的纯净;注重废水稀释倍数的影响。这些措施为快速ＣＯＤｃｒ值的可靠性提供了保证。     

风险分析的质量评价研究

风险分析的质量直接影响风险分析技术的应用 ,随着风险分析技术及其应用范围的扩大 ,建立评价风险分析的内容、结果及其方法和标准是十分必要的。为此 ,讨论了风险分析的质量概念 ;提出了一种评价风险分析质量的方法 ,该方法基于对风险分析过程的评价 ,利用检查表来发现风险分析的缺陷 ,同时研究了该方法的有效性和可靠性 ;最后 ,对方法的局限性以及提高风险分析质量的途径等其他相关问题进行了讨论。研究结果表明 :评价风险分析质量的方法能揭示风险分析中大多数的重大缺陷     

Utilizing Integrity Operating Windows (IOWs) for enhanced plant reliability & safety

Several industry codes, standards and recommended practices have been developed and utilized to maintain pressure equipment integrity and improve reliability. These industry standards focus heavily on inspections (time or risk based) and guidelines for operating equipment at conditions that enable a tolerable deterioration rate. RBI (risk based inspection), in effect, utilizes process conditions at a snapshot in time to recommend inspection strategies which can cover the span of the equipment's remaining life. On a day to day level, changes that occur in process conditions (excursions and upsets) are not fed back into the risk and criticality calculation. When such changes to operating conditions affect key process variables, new damage mechanisms could be introduced that affect the remaining life of an asset or accelerate existing damage mechanisms. The increase in risk resulting from these process changes goes unaccounted for until the effect of the deterioration is captured at the next inspection.Integrity Operating Windows (IOWs) are established limits for key process variables that can affect the integrity of the equipment if the process operation deviates from the established limits. The development of these IOWs requires fundamental understanding of the process and resulting damage mechanisms and is best facilitated by a team of corrosion and process engineers along with feedback from plant operators. A well-established IOW program is designed to provide real time notification of an increased risk to the integrity of an asset so that identified actions can be taken by the operators and/or plant managers proactively in a timely manner. Combining an RBI program with an IOW program can greatly increase its effectiveness and provide early recognition of equipment risks due to process changes. This paper will focus on the development of an IOW program and the benefits of combining it with a viable RBI program.     

机械设备可靠性分析与工程安全

指出了机械设备的可靠性对工程安全的重要意义。根据可靠性理论,对机械应力损伤和组织变化损伤这两种最常见的降低设备可靠性的损伤形式进行了讨论,并结合实例详细分析了判定机械设备工作状态的各种物理现象,以及估算剩余寿命的基本方法。     

对“安全驾驶适应性测验”的可行性研究

重点对“安全驾驶适应性测验”的信度和效度进行了研究和检验。通过对３１０ 名汽车驾驶员的答卷资料所处理结果表明：事故群驾驶员和非事故群驾驶员的心理品质差异主要表现在观察能力,判断能力,推断能力,辨别能力,思维的灵活性,注意的广度与稳定性,个性方面的安全驾驶态度,情绪的稳定性及是否过分自信等方面。另外,对年龄、文化程度、驾驶经验与事故率之间关系的考查表明,年龄与事故率之间的相关程度是十分显著的。说明该测验对于识别事故群驾驶员和非事故群驾驶员具有一定的区分性和预测性。     

振动试验失控分析及例证

随着航空航天产品技术和可靠性要求的提高,作为关键试验项目的振动试验条件愈来愈复杂,“振动失控”逐渐增多。本文从控制方式、控制点的选择和振动试验夹具的制造、安装等诸多方面进行分析,说明避免“失控”的方法。最后,文中给出实例,说明本文所提出方法的有效性。