Risk assessment of an oxygen-enhanced combustor using a structural model based on the FMEA and fuzzy fault tree

The oxygen-enhanced combustor has the advantages of high burning efficiency and low emissions. However, it should not be promoted for industrial use until its reliability and safety have been fully recognized. A new methodology is proposed to assess the risk of an oxygen-enhanced combustor using a structural model based on the FMEA and fuzzy fault tree. In addition, it is applied to a selected pilot semi-industrial combustor. To identify the hazard source comprehensively, the pilot is divided into four subsystems: the combustor subsystem, feed subsystem, ignition subsystem and exhaust subsystem. According to the operational parameters of flow (flow rate, temperature and pressure) and the component functions in different subsystems, the cause and effect matrix can be built using the structural model, and the relationship between the operational parameters and the effects of the change for the operational parameters on the system can be presented. Based on the results of cause and effect matrix, the FMEA can be built to describe the failed models and accident scenarios of the pilot. The main accident forms include leakage, injury, fire and explosion. Accordingly, with the severity and probability analysis of different accident forms, the fire and explosion accidents should be further accessed quantitatively using the fuzzy fault tree analysis. The fault trees can be obtained in accordance with the FMEA, and the qualitative assessments of the basic events can be collected by using expert scoring. A hybrid approach for the fuzzy set theory and weight analysis is investigated to quantify the occurrence probability of basic events. Then, the importance analysis of the fault trees, including the hazard importance of basic events and the cut set importance, is performed to help determine the weak links of the fire and explosion trees. Finally, some of the most effective measures are presented to improve the reliability and safety of the combustion system.     

Language‐based diversity and faultlines in organizations

Language‐based diversity is a relatively understudied area within diversity research. Drawing upon the social identity‐based fault lines literature, the present paper describes the effects of language‐based diversity within organizations operating in India. Interview‐based findings indicate that organizationally mandated languages are occasionally disregarded by employees in both national and multinational organizations. Respondents noted how even benign and momentary language switching can lead to the formation of language‐based groups and cause negative consequences such as feelings of being devalued. Respondents also noted strategies that let them attenuate negative effects of multilingualism while simultaneously leveraging its benefits. Overall, the present study indicates that momentary exclusion based on incomprehensible language, when experienced on a daily basis, may have a far‐reaching influence on individual and team functioning. Findings thus point to language use as a trigger that can activate social identity‐based fault lines. Copyright © 2014 John Wiley & Sons, Ltd.     

煤矿复杂事故树最小径集算法研究

文章在分析"成功树"法求事故树最小径集不足的基础上,结合煤矿五大灾害复杂事故树分析的特点,运用布尔代数和福塞尔行列法的基本原理,提出两种事故树最小径集的求解方法。通过一个煤矿复杂事故树分析实例,验证了方法的正确性和有效性,为实现事故树分析计算机化提供了有效的算法支撑。     

苏南老城区合流制管网的溢流污染特征

为了解苏南某市老城区合流制管网溢流污染特征,在苏南某市D排水系统溢流口采集了2种不同降雨强度的水样,检测水样中COD、SS、TN、TP和NH3-N等污染指标的浓度,并对不同降雨强度的水质变化特征与相关性进行分析。结果表明:较高降雨强度下SS、COD、TN、NH3-N和TP的浓度变化范围分别为37~695 mg/L、119~1 441 mg/L、6.2~26 mg/L、2.3~6.3 mg/L、0.07~1.48 mg/L;较低降雨强度下SS、COD、TN、NH3-N和TP的浓度变化范围分别为22~228 mg/L、180~535 mg/L、7.9~24.7 mg/L、3.2~24.2 mg/L 1.1~1.99 mg/L。由于不同降雨强度下雨污水冲击能量不同,在降雨强度较高的情况下,COD、TN与SS的线性相关系数分别为0.6954与0.6234,具有一定的相关性,而低降雨强度下无明显相关性。较高降雨强度时截留去除SS可以有效消减溢流污水中的COD和TN,对溢流污染的控制具有一定指导意义。     

油气管道伴行光缆失效统计及对策措施研究

油气管道伴行光缆在油气运输中起着十分重要的作用。由于外部环境的突发性、复杂性、不可控性,导致伴行光缆管理困难、混乱,断缆事件经常发生,给油气管道运输带来较大损失。本文以某公司为例,以2012~2018年光缆断裂事故数据为依托,运用鱼刺图方法梳理出光缆失效的4大原因类别,并应用故障树分析法对光缆失效进行分析,从最小割(径)集、结构重要度方面对光缆失效因素分析,并针对不同的危害因素提出合理的风险管控措施,构建光缆失效保护层,为今后油气管道伴行光缆风险管控提供指导。     

基于决策树支持向量机算法的船用设备故障诊断

目的 提高船用设备的智能化水平,增强船舶的安全性、可靠性,对船上设备进行状态监测,并基于监测数据对设备健康状况进行评估,对可能存在的故障工况进行识别.方法 通过采集机舱内的振动数据,对数据进行预处理、快速傅里叶变换,提取1/3倍频带特征,将倍频带谱信号作为特征向量,利用支持向量机算法进行模型训练及分类.对于船上多种工况...     

基于事故树分析的脚手架作业安全评价

为实现脚手架作业安全的系统性分析与评价,系统分析脚手架作业事故诱发机制,层层深入细化各影响因素,直至难以再细分的基本事件,确定相互之间的逻辑关系,建立脚手架事故树。在分析最小割集的基础上,采用专家调查法,给出各基本事件发生概率的经验估计,进而确定顶事件概率。在此基础上,通过敏感性分析,揭示基本事件对于顶事件的贡献程度。研究结果表明,脚手架作业事故发生的主要原因包括脚手架上有人、设计不合理、架设错误、材料不合格等,为保障作业安全,尤其需要加强作业人员在脚手架作业中的警惕性,注重脚手架设计理论计算,同时规范脚手架架设程序,选择合乎规格的脚手架材料。     

基于事故树的调水线路水质污染风险效应

中尺度水体污染风险评价的方法尚处于探索阶段.以连通保定市王快水库和西大洋水库向白洋淀补水项目为例,提出按事件属性比例确定单事件概率的方法,并使用故障树法分析了总体引水水体污染风险水平.结果表明,沿线污染源对引水水体存在较大风险,现状风险概率为0.373,污染物一旦在项目运行期进入水体可给水体增加约64.53 mg/L的COD、4.57 mg/L的氨氮、0.066 mg/L的挥发酚,增加值较大.按事件属性比例确定基本事件概率,对不确定性水质风险评价具有较强的适用性.     

A review on transient stability of DFIG integrated power system

With the increasing penetration of doubly fed induction generators (DFIGs), the impact of the DFIG on transient stability attracts great attention. Transient stability is largely dominated by generator types in the power system, and the dynamic characteristics of DFIG wind turbines are different from that of the synchronous generators in the conventional power plants. The analysis of the transient stability on DFIG integrated power systems has become a very important issue. This paper reviews the current research on the issue from two aspects. One is to describe the methods to improve the fault ride through capability of DFIG wind turbines and the other is to analyse the impact of the DFIG wind farm on transient stability of power systems.     

环境试验过程控制和试后处理的问题分析

论述了环境试验实施过程控制和试后恢复,重点分析实施中易忽视的问题,提出较为科学合理的方法.