可燃气体报警器的选点安装与使用维护

可燃气体报警器由探测器与报警仪构成,广泛应用于石油、燃气、化工、油库等存在可燃气体的石油化工行业,可检测室内外危险场所的泄漏情况。当被测场所存在可燃气体时．探测器将泄漏气体转换成电压信号或电流信号传送到报警仪表,仪器显示出可燃气体爆炸下限的百分比浓度值。当可燃气体浓度超过报警设定值时．该报警器发出声光报警信号提示值班人员及时采取安全措施,避免燃爆事故发生。     

超市防盗凭什么误会我?

江宁消费者张先生在江宁一家超市购物,付完钱出门时,门口的报警器突然呜叫起来.超市工作人员赶来把他拦住,要求张先生接受检查.无奈之下,张先生只好将随身携带的物品全部取出来,接受超市检查.结果证明,张先生并没有偷东西,造成报警器"误认"的罪魁祸首是他随身携带的一张加油卡.受了委屈的张先生要求超市道歉,但超市以"机器发生故障"为由,不愿道歉.张先生于是向当地消协投诉.……     

可燃气体报警器的选点安装与使用维护初探

可燃气体报警器由探测器与报警仪构成,是石油、燃气、化工、油库等存在可燃气体的石油化工行业检测室内外危险场所的泄漏情况的。当被测场所存在可燃气体时,探测器将气信号转换成电压信号或电流信号传送到报警仪表,仪器显示出可燃气体爆炸下限的     

卷积神经网络在燃气管道故障诊断中的应用

为了提高燃气管道泄漏故障的诊断能力,判断燃气管道故障泄漏的类型,将深度学习神经网络应用到燃气管道故障诊断领域,提出了一种基于卷积神经网络与softmax分类器的燃气管道故障诊断技术。选取燃气管道故障中的9种特征参数作为模型的原始输入量,经过卷积神经网络的特征提取、参数重构、soft-max分类,最终达到诊断的效果。将得到的卷积神经网络模型应用在实验室的燃气管道故障泄漏检测系统中,结果表明,这种模型在燃气管道故障识别中的准确率稳定在92. 54%,与BP神经网络相比该方法有明显的准确率和稳定性。     

燃气管线相邻地下空间安全监测方法及其应用研究

城市燃气管线泄漏极易导致火灾爆炸等重大安全事故,严重威胁城市安全。通过监测预警技术,快速准确地发现泄漏,防止可燃气体聚集,是保障燃气管线安全运行的重要手段。提出了一种燃气管线相邻地下空间安全监测预警方法,构建了风险识别、预测预警、分析推演和决策支持一体化安全监测系统,并应用于合肥市2.5 km燃气管线及其相邻空间高风险区域。结果表明,提出的燃气管线相邻地下空间安全监测方法可用于燃气管线泄漏监测预警,以减少或避免燃气泄漏引发的火灾爆炸事故。     

深埋管道中泄漏孔对燃气泄漏影响的数值模拟*

为研究泄漏孔的各种因素对深埋土体中燃气管道泄漏的具体影响,采用1个包含燃气管道的三维模型,研究单个泄漏孔的大小、位置、形状对于埋地燃气管道泄漏的影响,并建立大小相等的双泄漏孔的燃气管道,确定双泄漏孔间距对于燃气泄漏扩散的影响。结果表明:泄漏孔越大,燃气在土壤中的扩散速度越快,且泄漏孔的大小对深埋燃气管道泄漏的影响最大;泄漏孔位置的影响次之,顶部与侧壁的泄漏孔扩散速度相差无几,底部泄漏孔的扩散速度远低于前2者;双泄漏孔间距的影响较小,双泄漏孔的距离越小,甲烷的扩散速度越快;泄漏孔形状对于深埋燃气管道泄漏扩散的影响非常小。     

基于OpenFOAM的综合管廊舱内燃气泄漏扩散数值模拟

为实现综合管廊燃气泄漏扩散的精确高效模拟分析,进而为综合管廊燃气泄漏事故的安全防控提供技术支撑,利用OpenFOAM对城市地下综合管廊舱内燃气泄漏扩散进行数值建模计算,研究分析通风受限空间内的燃气泄漏扩散规律,并结合对应急响应时间的分析验证了通风策略的有效性。研究结果表明:气体射流作用与浮升力作用是影响综合管廊燃气泄漏扩散浓度分布的重要因素,采取合理的通风措施可有效加速燃气的流动与扩散,缩短燃气泄漏报警响应时间,有利于燃气泄漏事故应急决策与应急救援的快速实施。     

燃气爆炸事故的原因与对策

1 家庭燃气爆炸事故的原因及预防 　　在用燃气(包括煤气、天然气、液化石油气)做饭时,燃气从灶眼里喷出来,都燃烧掉了。如果泄漏出来没有燃烧,在空气中达到一定浓度,这时遇到明火,就会在瞬间全部燃烧,剧烈发热而膨胀,这就是可怕的爆炸。这个能引起爆炸的浓度,叫做爆炸极限。能引起爆炸的最低浓度叫爆炸下限,能引起爆炸的最高浓度叫爆炸上限。不同的燃气其爆炸极限范围也不同,燃气的热值越高,它的爆炸下限越低,越容易达到爆炸浓度。     

可拓综合评价在燃气系统泄漏事故应急救援中的应用

燃气系统发生泄漏,如不能及时有效进行应急救援,极易引发严重的事故后果,因此,准确确定应急响应等级,进行有针对性的救援工作是控制燃气系统泄漏事故后果严重性的关键。从众多影响因素中,分析并确定了影响燃气系统泄漏事故后果严重性的主要因素,对各因素严重程度进行了等级划分。引入了可拓工程方法,建立了燃气系统泄漏事故后果严重性可拓综合评价模型,阐述了评价步骤和方法。当各影响因素分属不同等级时,根据所建模型能综合确定燃气系统泄漏事故后果严重性等级,依此进行事故应急救援分级响应。该方法能够克服人为评判失误,有利于指导有效事故救援,控制事故影响范围。运用该模型对一事故案例进行了计算,计算结果表明此方法用于确定应急救援响应等级是可行的。     

基于声波法燃气管道单双点泄漏安全检测研究

为提前对燃气管道多点泄漏进行防范,本文基于燃气管道安全运行的重要性,搭建燃气管道泄漏实验平台,建立孔径大小相等的双泄漏孔燃气管道,研究燃气管道单、双点泄漏的声源特性及传播规律。结果表明：单、双点泄漏都会随着压力增大而逐渐增大;单点泄漏时域振幅普遍比双点泄漏时振幅小;声波幅值随着压力的增加而增加,当压力和孔间距一定时,管道中声波信号幅值随着距离增加而逐渐减小,最后趋于平稳,并且靠近泄漏点的声波信号均大于未泄漏处的声波信号。本文研究燃气管道单、双点泄漏,有利于对城镇燃气管道进行实时监测,为燃气管道安全检测提供理论基础。     

让“绿色”汽车更名地走进我们的生活

正当人们积极探讨和解决由于燃煤造成的煤烟型大气污染、植被的破坏造成的沙尘暴，等等，危及人类生存环境的问题，并取得显著成效的时候，另一种大气污染却随着经济建设的迅速发展而悄然而至，这就是汽车尾气排放造成的大气污染。许多发达国家都曾受过汽车尾气排放污染之苦。1943年在美国洛杉矶地区就曾出现过一种光化学烟雾，这就是历史上所谓的“洛杉矶烟雾”。     

Bayesian networks make LOPA more effective,QRA more transparent and flexible,and thus safety more definable!

Quantitative risk analysis is in principle an ideal method to map one’s risks, but it has limitations due to the complexity of models, scarcity of data, remaining uncertainties, and above all because effort, cost, and time requirements are heavy. Also, software is not cheap, the calculations are not quite transparent, and the flexibility to look at various scenarios and at preventive and protective options is limited. So, the method is considered as a last resort for determination of risks. Simpler methods such as LOPA that focus on a particular scenario and assessment of protection for a defined initiating event are more popular. LOPA may however not cover the whole range of credible scenarios, and calamitous surprises may emerge.In the past few decades, Artificial Intelligence university groups, such as the Decision Systems Laboratory of the University of Pittsburgh, have developed Bayesian approaches to support decision making in situations where one has to weigh gains and costs versus risks. This paper will describe details of such an approach and will provide some examples of both discrete random variables, such as the probability values in a LOPA, and continuous distributions, which can better reflect the uncertainty in data.     

Methods for more accurate determination of explosion severity parameters

Accurate determination of explosion severity parameters (p_max, (dp/dt)_max, and K_St) is essential for dust explosion assessment, identification of mitigation strategy, and design of mitigation measure of proper capacity. The explosion severity parameters are determined according to standard methodology however variety of dust handled and operation circumstances may create practical challenge on the optimal test method and subsequent data interpretation. Two methods are presented: a statistical method, which considers all test results in determination of explosion severity parameters and a method that corrects the results for differences of turbulence intensity. The statistical method also calculates experimental error (uncertainty) that characterises the experimental spread, allows comparison to other dust samples and may define quality determination threshold. The correction method allows to reduce discrepancies between results from 1 m³ vessel and 20-l sphere caused by difference in the turbulence intensity level. Additionally new experimental test method for difficult to inject samples together with its analysis is described. Such method is a versatile tool for explosion interpretation in test cases where different dispersion nozzle is used (various turbulence level in the test chamber) because of either specific test requirements or being “difficult dust sample”.     

浅谈儿童目动综合症与铅中毒

儿童多动综合症是表现为与同龄儿童相比，有长时间持续的、明显的注意力不集中和活动过度为主要特征的一组行为障碍。国内报道本症患病率为1.3％～15.9％，且以男孩为多见，起病年龄以5～8岁占多数。其临床表现主要为5个方面：(1)注意障碍；(2)活动过度；(3)情绪不稳，任性冲动；(4)认知障碍，学习困难；(5)行为问题，适应困难。本病的病因，迄今仍不清楚，但由于与微量元素关系的研究日渐深入，有人认为血铅增高和低铁与本症密切相关。为此，本文就如何预防儿童铅中毒，减少多动症的发生作一综述。 1 儿童铅中毒的标准 铅是具有导致神经性病症的重金属元素。铅进入人体后，主要从尿中排出，正常人每日由尿排铅约20～80μg。     

基于流固耦合的多弯管路系统动力学分析

为研究多弯管路系统的动力学特性,基于流固耦合和有限元原理,对充液L型管道的固有特性进行了数值模拟,并与TMM(传递矩阵法)进行了对比,证明了数值模型的合理性。建立了水下多弯管路的数值模型,进行了流固耦合模态分析,研究了壁厚、管径对管路固有频率的影响规律。并对非定常流下多弯管路系统的动力响应进行了分析,研究了壁厚和波动速度对管道振动的影响规律。研究结果表明:考虑管内、外流体与管道三者耦合时的管道固有频率比只考虑管内流体与管道二者耦合和不考虑耦合时小,但流固耦合作用对管道模态振型的影响较小;管道的固有频率随管径和壁厚的增大而增大, 气体与管道之间耦合作用对管道固有频率的影响小于液体;非定常流下,多弯管路的振动幅值随着壁厚的增大而减小,随着波动速度的增大而增大。     

实施项目管理体系的战略意义和作用

一个安防项目从概念(安全需求)的形成、立项申请、进行可行性研究分析、项目评估决策、设计需求书确定、现场考察、方案设计、程序开发、测试和主要设备的选型及采购、项目的组织实施、计划的制定、工期质量和成本控制、直到完工验收、交付使用、收尾,要经历很多不可缺少的工作环节.     

Sometimes less is more: Directed coping with interpersonal stressors at work

Within the coping literature, researchers have long been interested in identifying ways in which individuals can improve their coping efforts, making them more effective and thereby reducing the harmful effects of stressful encounters. Although Lazarus and Folkman's transactional model has greatly advanced understanding of the coping process, there continues to be methodological and conceptual challenges that have hindered understanding of the mechanisms behind effective coping. Addressing these issues in the use of a novel approach of analyzing variation in coping (i.e., directed coping) at both the coping event and person coping levels, the current study examined the process of coping with work stress and the beneficial coping outcomes associated with using a directed coping strategy. A total of 143 nurses completed up to 12 weekly surveys online, reporting on weekly stressful interpersonal conflicts and how they coped with them. Results from multilevel analyses supported predictions that greater directed coping at both the level of the coping event and person is associated with improvements in occupational health outcomes even after controlling for other coping factors. Implications of these results are discussed in relation to future research on coping effectiveness and workplace applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Towards more effective methods for changing perceptions of noise in the workplace

This research examined the intervention effects of a simple one-hour training session designed to raise the awareness of noise as a workplace hazard in conjunction with general safety perceptions and attitudes in the workplace. Several sessions were conducted for two organizations, at different locations. Control groups were also employed with both organizations. Participants were questioned using a ‘safety climate’ questionnaire and a ‘noise at work’ questionnaire. The results indicated that awareness of noise as a workplace hazard can be significantly increased with a simple intervention.