Failure mode effects and criticality analysis of water supply systems' risks: Path to water resources planning and policy

The risk assessment of drinking-water supply systems in Ogun State, Nigeria, was carried out using the failure mode effects and criticality analysis (FMECA) approach. The FMECA is a systemic process that identifies potentials failure modes within a system and was chosen for its causes and effect approach to assessing risks. The objective of the study was to assess drinking-water supply systems and identify water supply systems' risks from source to point-of-use. Three major water supply sources were selected for assessment: hand-dug wells, boreholes and public water supply sources. The sources were assessed by identifying the potential failure modes that exist within the water supply sources and the consequence of the identified risks on relevant stakeholders. The sources were divided into modules. The risk in each module was determined by multiplying failure rate (likelihood) and consequences of failure of the module. Risk reduction options include repair and maintenance measures, information dissemination on the procedures to reduce the identified risks and preventive and regulatory approaches. The resulting risks were characterized using FMECA risk matrix of each water source and classified into high, medium and low risks. Well cover and lining were the most risk-prone modules for hand-dug wells (high and medium risks). Broken well cover and lining serve as pathways to contaminants into the well. Casing and screen modules posed the highest risk for boreholes, recording high to medium risk. Cracked casing and broken screen provide access for contamination into boreholes. The module with the greatest risk for public water supply source was the point-of-abstraction/use module. Unsanitary containers and poor storage conditions is believed to be responsible for recontamination of the treated water Climate variability, environmental and anthropogenic influences were observed to be responsible for most of the identified risks. The study highlights that consumer participation is vital in ensuring the availability of safe drinking-water, stressing consumer education as the most important channel. The study recommends the use of FMECA to ensure implementing preventive and regulatory measures by water monitoring agencies and for water resources planning and policy making.     

基于模糊理论的多属性航空安全风险评估

在对航空安全风险因素从重要度、危害度、难检度和可能度4维属性划分的基础上,利用模糊理论、欧几里得距离公式和FMECA原理,建立了多属性风险因素的风险评估模型。通过专家问卷和对航空安全风险因素辨识,利用该模型对航空安全风险进行了评估,得到了各项风险因素的关键性指数排序;并对该风险评估模型进行了敏感度分析。该模型结构简单,意义明确,可直接用来指导安全管理工作。     

扩散硅压力传感器工艺过程的FMECA分析

通过将扩散硅压力传感器的每一道工序作为“部件或元件”，构成“工艺”的可靠性框图，进行ＦＭＥＣＡ分析；指出了各个工艺所产生的失效模式、失效原因、失效效应和改进措施。     

可靠性分析技术

针对目前多数国内机床制造企业可靠性意识差或想做可靠性分析却苦于理论和实践知识缺乏的状况,系统介绍了故障模式、影响及危害性分析、故障树分析、热分析、应力均衡分析、匹配性分析等5种常用可靠性分析技术。介绍了5种可靠性分析技术的分析流程、实施要点、分析原则等。这些可靠性分析技术已成功应用于机床、汽车、航空航天等多个行业,事实证明,通过可靠性分析可以有效提高产品可靠性。     

装备研制可靠性工作项目风险模糊综合评估

针对现有的可靠性工程管理缺少风险管理环节,利用质量功能展开技术,建立蕴含在装备研制过程中可靠性工作项目的风险因素递阶层次模型,实现了风险因素权重的排序,在此基础上对项目风险进行模糊综合评估。结合实际型号工程研制阶段的FMECA工作项目进行实证研究,给出了详细的评估过程和步骤。结果表明,采用这种定性与定量相结合的方法。很好地解决了可靠性工作项目风险复杂性和相关性问题。     

风险评估技术在无菌粉针剂工程中的应用

为强化风险评估技术及风险管理在无菌制剂中的应用,从论述FMEA/FMECA、HACCP风险评估技术及方法入手,探讨了影响无菌制剂产品质量的考察因素及风险评估技术在无菌制剂中的初步应用,以期为药品质量风险管理的实施提供借鉴。     

ANP/RPN: a multi criteria evaluation of the Risk Priority Number

This paper presents an advanced version of the failure mode effects and criticality analysis (FMECA), whose capabilities are enhanced; in that the criticality assessment takes into account possible interactions among the principal causes of failure. This is obtained by integrating FMECA and Analytic Network Process, a multi‐criteria decision making technique. Severity, Occurrence and Detectability are split into sub‐criteria and arranged in a hybrid (hierarchy/network) decision‐structure that, at the lowest level, contains the causes of failure. Starting from this decision‐structure, the Risk Priority Number is computed making pairwise comparisons, so that qualitative judgements and reliable quantitative data can be easily included in the analysis, without using vague and unreliable linguistic conversion tables. Pairwise comparison also facilitates the effort of the design/maintenance team, since it is easier to place comparative rather than absolute judgments, to quantify the importance of the causes of failure. In order to clarify and to make evident the rational of the final results, a graphical tool, similar to the House of Quality, is also presented. At the end of the paper, a case study, which confirms the quality of the approach and shows its capability to perform robust and comprehensive criticality analyses, is reported. Copyright © 2011 John Wiley and Sons Ltd.     

An integrated structural framework to cost-based FMECA: The priority-cost FMECA

The Failure Mode, Effects and Criticality Analysis (FMECA) methodology is a widely recognized tool for the study and reliability analysis of a design or process. Many authors in the field have emphasized the usefulness of this particular method as well as its limitations. In particular, there are two main criticisms regarding the Risk Priority Number (RPN) method of calculation and the extreme difficulty in considering the variable of the corrective action cost in the analysis. The main scope of this work is to present a new integrated approach, named priority-cost FMECA (PC-FMECA), in order to exceed these limits. Making reference to a paper by Braglia [MAFMA: multi-attribute failure modes analysis. Int J Qual Reliab Manage 2000; 17(9)], this study proposes a method which allows for the calculation of a new RPN and the introduction of the concept of Profitability taking into consideration the corrective action cost. The study is divided in three fundamental phases: critical analysis of the FMECA model, proposal and development of the PC-FMECA and presentation of an implemented case study in the automotive field.     

基于FMECA修正危害度的数控车床关键子系统可靠性分配

基于故障模式、影响及危害性分析理论,以数控车床关键子系统修正危害度的取值大小作为子系统可靠性指标分配值的衡量标准,指导可靠性分配。将严重度取值非线性化,考虑降低失效率成本问题,将两者结合起来得到修正危害度的表达式,更好地反映了可靠性设计过程中失效模式影响程度的重要性。介绍了危害度分析的相关理论,分别论述了基于传统危害度及修正危害度的可靠性分配方法。最后,将可靠性分配方法应用到数控车床关键子系统可靠性分配的实例中,并加以比较。结果表明,基于修正危害度的可靠性分配方法充分考虑了严重度水平较高子系统的影响以及降低子系统失效率的难易程度,其能够有效地通过可靠性分配结果指导可靠性设计,对于危害度较高、可靠度不达标的子系统在外购、设计、加工、装配等环节应予以足够重视,从而保证整机的平均无故障间隔时间（MTBF）达到要求。     

数控车床故障模式影响与致命性分析

应用FMECA法对攻关产品某系列数控车床进行故障模式影响与致命度分析．掌握了该数控车床的故障发生情况及其子系统的致命度,得出CNC系统是故障多发的原因,以及转塔刀架系统是致命度最高的部件,并提出了相应的改进措施。取得了明显的成效．