Initiating events and independent protection layers

Layer of protection analysis (LOPA) is a semiquantitative tool for analyzing and assessing process risk. The tool has grown greatly in popularity and usefulness since the publication of the first CCPS/AIChE guidebook on the subject, Layer of Protection Analysis, Simplified Process Risk Assessment (LOPA). This article is a summary of a new CCPS guideline book that includes the following:

• Initiating events (IEs).
• Independent protection layers (IPLs).
• Criteria for identifying the value of each prospective IE and prospective IPL.
• Example IE and IPL data.

This book is a necessary reference for those applying the LOPA methodology. © 2009 American Institute of Chemical Engineers Process Saf Prog, 2009     

Improved integration of LOPA with HAZOP analyses

Integrating Layer of Protection Analysis (LOPA) with Hazard and Operability Analysis (HAZOP) has many advantages over performing these studies separately. The merits include: fewer actions from the combined effort compared to performing only a HAZOP; team continuity resulting from the combined effort as opposed to two separate teams having possibly differing points of view; and, ultimately, a time and cost savings realized by the combination. This integration defines the risk associated with a given scenario, enabling better decisions that impact business assurance. By using the Center for Chemical Process Safety guidelines to define the independent protection layers upfront, the gray areas can often be reduced or eliminated; thereby enabling a more thorough LOPA. Examples include taking credit if a unit has two independent operators (outside and inside) responding to critical alarms, or taking credit for centralized control rooms that may allow immediate operator interaction and response. This article shows how the guidelines have been used successfully in joint HAZOP/LOPA studies, and describes an initial preparation protocol that can ensure high-quality results. © 2009 American Institute of Chemical Engineers Process Saf Prog, 2009     

LOPA as practiced at a global manufacturing API facility

The standard risk assessment practices used in industry since the OSHA 1910.119 regulation was issued, are to conduct Process Hazard Analyses (PHAs) for hazardous and exothermic (or otherwise high risk) processes. During PHAs, the potential consequences of an undesired event are evaluated along with the safeguards that exist to mitigate the consequences or reduce the frequency of the event. If the PHA team determines that the risk is still not tolerable, additional safeguards are recommended to reach a tolerable level of risk. Typically, a Quantitative Risk Assessment can be completed to evaluate the effectiveness of these existing or newly proposed safeguards. Unfortunately, this is a complex and time-consuming task. The relatively new methodology of Layer of Protection Analysis (LOPA) allows a PHA team to evaluate the effectiveness of safeguards in reducing risk in an efficient yet semiquantitative fashion using some basic assumptions and standard lookup tables. The LOPA methodology can be utilized to evaluate the effectiveness of Safety Instrumented Functions (SIF) (e.g., automated critical interlocks and alarms) to achieve a tolerable risk. The LOPA methodology provides consistency in an approach to risk assessments and communications. It can support an effective mechanical integrity or risk-based maintenance system for critical components of an SIF. This article describes LOPA and includes several scenarios that will provide an overview of how the LOPA methodology is used in a multibatch pharmaceutical facility. © 2009 American Institute of Chemical Engineers Process Saf Prog, 2009     

圆柱齿轮减速器可靠性分析

阐述了圆柱齿轮减速器的可靠性定义、考核项目和故障树模式，介绍了试验室疲劳寿命试验和工业现场使用数据统计两项可靠性评定方法。     

圆柱齿轮减速器可靠性分析

可靠性是衡量产品质量的一项重要指标,介绍了圆柱齿轮减速器的可靠性定义及考核项目。对圆柱齿轮减速器的故障分析及分类,应用故障树和工业现场统计对圆柱齿轮减速器的可靠性进行分析,目的在于分析出圆柱齿轮可靠性的指标及可靠性分析的重要性。     

事故树分析在煤与瓦斯突出中的应用

本文针对煤与瓦斯突出的三要素,运用事故树分析方法对煤与瓦斯突出事故进行评价,并根据评价结果,提出综合防突措施。     

LOPA misapplied: Common errors can lead to incorrect conclusions

Layer of Protection Analysis is a powerful tool for quantitative risk assessments. If applied correctly, it can provide quick and efficient guidance on what additional safeguards are needed, if any, to protect against a given scenario. If misapplied, an overly conservative calculation of risk may result in over-instrumentation, additional life-cycle costs, and spurious trips. A nonconservative calculation of risk could result in an under-protected system and unacceptable risk of an undesired consequence occurring. This article describes several categories of common errors, some overly conservative and some nonconservative. Case studies of actual plant scenarios are used to illustrate. © 2009 American Institute of Chemical Engineers Process Saf Prog 2009     

川渝地区输气管道第三方破坏故障树分析

第三方破坏是引起输气管道失效的主要因素之一,直接影响输气管道的可靠性和使用寿命。针对川渝地区引起输气管道第三方破坏的各个因素进行系统分析,建立了以第三方破坏致使输气管道失效为顶事件的输气管道第三方破坏故障树。通过对输气管道第三方破坏故障树的分析,得到了故障树的各阶最小割集和引起川渝地区输气管道第三方破坏的主要因素,并提出了相应措施以预防输气管道遭到第三方破坏。     

基于多地区城市地下综合管廊应用PPP模式风险评价

在对综合管廊应用PPP模式的风险进行识别的基础上,利用灰色故障树模型(FTA)对应用PPP模式的城市地下综合管廊项目进行全生命周期分析,筛选风险产生的基本事件,通过确定对于基本事件关联度的大小,得出其需要重视的基本事件。并通过改进关联度函数进行实证分析,验证评价方法的科学性及实用性。最后,提出相适宜的管理意见对风险进行规避,对城市地下综合管廊工程项目应用PPP模式风险管理具有一定指导和借鉴意义。     

水驱抽油机井管杆偏磨可靠性模糊故障树分析

应用模糊集运算规则及性质构建模糊故障树模型，采用最小和最大模糊算子简化故障树结构函数的计算过程。从概率结构重要度的定义出发．通过语言变量表达底事件发生状态的模糊性，将底事件随机发生时的模糊性考虑进来，从而使故障树分析中，将底事件发生的随机性和模糊性同时处理成为可能。利用模糊距离概念，将底事件结构重要度概念从概率空间推广到模糊集中，得到模糊距离重要度。这样．当底事件发生状态不能明确规定时，模糊距离重要度在评价其贡献方面是非常有效地：通过对水驱抽油机井管杆偏磨失效模糊故障树实例分析，找出发生管杆偏磨失效的最薄弱环节，为科学治理和有效控制管杆偏磨失效，降低水驱抽油机井检泵率提供充分依据。     

水驱抽油机井管杆偏磨失效故障树分析

从系统可靠性理论出发，在对水驱抽油机井管杆偏磨失效长期、大量调研的基础上，根据抽油机井发生管杆偏磨失效后．检泵作业结果和油井工作资料的综合分析，运用演绎法建立水驱抽油机井管杆偏磨失效的故障树．从而找出了发生管杆偏磨失效的关联因素及其组合应用可靠性数学计算各关联因素对顶事件发生的结构重要度，从而发现系统最薄弱环节，为科学治理和有效控制管杆偏磨失效．降低水驱抽油机井检泵率提供了充分依据．     

深水固井作业井喷事故的蝴蝶结模型

由于浅层水和浅层气等高压流体预测的困难性和危害性,深水固井作业过程中面临很多的难题。以往人们总是关注钻进过程中的井喷事件的防控,但2010年英国石油公司(bp)"深水地平线"钻探平台发生爆炸事故改变了人们的看法,固井作业质量差同样会导致井喷。对井喷处理措施的不当,不仅会造成井毁人亡的恶性事故,同时大量溢油入海更会严重破环海洋环境,造成严重的生态灾难。以bp事故报告为依据,将事故树分析与事件树分析相结合,对深水固井作业溢流的原因、井涌监测失败的原因和井喷的后果进行了详细分析,分别建立了深水固井作业溢流和溢流井涌监测失效的故障树。并结合井喷事件树建立了固井作业井喷事故的蝴蝶结模型。该模型为深水固井作业过程井喷事故的防控提供了一定的依据和参考。     

模糊事故树法在贵州某煤矿瓦斯爆炸事故分析中的应用研究

贵州省是煤矿瓦斯事故的高发地区,瓦斯事故通常会有大量人员伤亡,造成煤矿重大经济损失,本论文运用安全系统工程的知识,把事故树和模糊数学相结合,以贵州省某煤矿瓦斯爆炸事故为案例,建立煤矿瓦斯爆炸事故分析模型,分析煤矿瓦斯爆炸事故。     

基于三角模糊和故障树理论的西气东输管道第三方破坏风险分析

依据第三方施工对管道造成破坏的影响因素,建立故障树。针对基本事件发生概率不确定的情况下,引入三角模糊理论,将基本事件的发生概率描述为模糊数,采用正态的R-L模糊数为参照函数,修正了各基本事件的发生概率,通过模糊运算规则得出第三方施工对管道破坏概率的区间值。应用中值法确定各底事件的模糊重要度,并对此进行排序,确定主要影响因素,最后提出相应的措施以减少第三方施工对管道的破坏。     

基于模糊动态故障树的化工设备故障诊断方法研究

本文针对化工设备故障具有模糊性、动态性的特点,提出了建立模糊动态故障树对其进行预测诊断,重点对模糊动态故障树定量分析方法进行了研究,提出了基于最小割集、割序的定量分析方法。该方法将模糊动态故障树分解为模糊静态子树和模糊动态子树,然后分别建立以最小割集和最小割序为基础的定量计算模型,同时引入了弱三角范数的概念以减少由于数据模糊性扩散而引起计算结果不准确的现象。最后给出了最小割集、割序和底部事件重要度的计算公式,分析了化工设备故障诊断的流程,并通过实例验证了该方法具有计算准确,效率高,通用性强的特点,适用于化工设备的故障诊断。     

Evaluating the newer salesperson

This article reports the results of an experiment examining the effect pattern of performance and information format have on sales managers performance appraisal.     

Evaluating market segmentation approaches

This article is concerned with managing and monitoring industrial market segmentation. The economics of market segmentation are overviewed, and an attempt is made to relate the segmentation tool to costs incurred. It is recommended that managers employ more economical methods of segmentation before using more costly parts of the marketing mix. A monitoring scheme is presented with two components that helps managers assess how well their segmentation strategy converts customers to the firm, meets market needs, and represents an efficient allocation of resources.     

“一带一路”视角下中国 - 海合会 FTA 经济效应研究——基于 GTAP 的模拟分析

本文基于最新的GTAP9数据库,将石化产业作为敏感产业并设定3种不同的模拟情景分析了中国-海合会FTA对不同国家的经济影响,结果显示：中国-海合会FTA对成员国有较强的正面效应,但对双方共同的主要贸易伙伴和“一带一路”其他沿线国家产生不同程度的反向冲击。中国和海合会应加快谈判进程以早日获得贸易自由化收益,并规避受损国家可能的暗中掣肘,同时发挥中国-海合会FTA的示范效应和“多米诺骨牌”效应,拓展与“一带一路”沿线FTA的广度和深度,深入推进“一带一路”倡议。     

机械设备故障诊断发展历程及展望

机械故障诊断包括状态监测、分析诊断和故障预测,其实施过程可归纳为信号采集、信号处理、状态识别与诊断决策。本文对机械故障诊断的基本过程进行了了论述,介绍了机械故障诊断技术的发展历程,尤其是在我国的几个发展阶段,以及现阶段在我国的发展现状、水平和应用情况,并对机械故障诊断和监测技术的发展趋势进行了展望。     

Modularity and intellectual property protection

Modularity is a means of partitioning technical knowledge about a product or process. When state‐sanctioned intellectual property (IP) rights are ineffective or costly to enforce, modularity can be used to hide information and thus protect IP. We investigate the impact of modularity on IP protection by formally modeling the threat of expropriation by agents. The principal has three options to address this threat: trust, licensing, and paying agents to stay loyal. We show how the principal can influence the value of these options by modularizing the system and by hiring clans of agents, thus exploiting relationships among them. Extensions address screening and signaling in hiring, the effects of an imperfect legal system, and social norms of fairness. We illustrate our arguments with examples from practice.© 2014 The Authors. Strategic Management Journal published by John Wiley & Sons Ltd.