建筑火灾烟气毒性分析

本文介绍了建筑火灾烟气的概念、产生以及特征,阐述了烟气的危害与烟气毒性评价方法,并讨论了烟气毒性研究的发展方向.     

火灾中燃料失重速率与烟气向远距离处迁移关系的实验研究

通过不同燃料在模拟房间—走廊结构实验装置中的燃烧实验，较系统地揭示了不同材料燃烧时失重速率变化与远距离处烟气迁移速度和CO浓度的关系。实验得到了不同燃料燃烧时的失重速率曲线。研究发现，多数燃料的烟气传播速度与失重速率呈线性变化的关系，油料和布料的烟气传播速度对质量失重速率的变化非常敏感；某些燃料燃烧产生有毒成分的峰值迁移到远距离处需要较长的时间。     

隧道火灾烟气发展的模拟计算研究

分析了隧道火灾的特点，运用区域模拟和场模拟的方法，通过一假定的隧道火灾算例，分析了几种不同情况下隧道火灾的烟气发展情况。讨论了烟气温度、高度的变化情况，得到了不同区段火和烟气对人构成威胁和对隧道结构造成破坏的情况，最后对隧道火灾的防治提出了一些建议。     

细水雾与火灾烟气相互作用的实验和数值模拟研究

通过模拟实验研究了细水雾与火灾烟气的相互作用,揭示了细水雾作用下烟气温度及组分浓度的变化规律。同时利用FDS程序计算了细水雾作用下烟气温度和组分浓度随时间的变化规律,利用实验数据对计算结果进行了准确性验证。结果表明只要计算网格匹配合理,FDS可以较为准确地预测细水雾作用下烟气温度和组分浓度的变化规律。在实际的细水雾灭火系统工程应用中,可以利用FDS场模拟方法预测灭火过程中火场温度及组分浓度等特性参数的变化规律,这对灭火系统的优化设计具有一定指导意义。     

舰船封闭舱室火灾烟气特性分析

封舱灭火作为舰船火灾消防的有效手段之一,研究封闭舱室火灾烟气特性具有重要的工程应用价值。本文从封闭舱室火灾发展和烟气特性分析两个方面,建立了封闭舱室火灾烟气高度模型、熄火时间模型、熄火时刻舱室温度模型和CO浓度模型,并采用算例对这一理论模型进行了验证。研究结果表明:这一理论模型能够较好地对封闭舱室火灾烟气的生成特性和流动特性进行理论分析,能够为舰员封舱灭火场景下的损害管制提供参考。     

有机硅化合物的潜在危害性及其防护措施

本文总结了部分有机硅化合物的毒性、燃烧性、爆炸性、腐蚀性资料及物性数据，提出了相应的防护措施，旨在提醒该行业人员：部分有机硅单体和中间体具有不同程度的毒害性和危险性，有机硅生产中同样潜伏着各种危害因素，从事有机硅研制、生产绝不可掉以轻心，而应采取相应措施，以确保生产安全和操作人员身体健康。     

地铁车站出入口火灾烟气特性的模拟研究

利用木垛火模拟地铁火灾的演化过程，在地铁车站出入口的缩尺度模型中进行模拟实验。采用温度相对值，分析地铁火灾沿车站出入口烟气温度下降的规律及其影响因素。通过实验图像，对烟气分层所需条件以及区域模拟方法在地铁火灾烟气特性研究中的适用性进行了讨论。气体成分测量结果表明，出口处烟气中CO的质量分数存在阶梯状变化的规律。     

侧向集中排烟作用下隧道火灾烟气逆流长度规律试验研究

烟气逆流长度是隧道火灾进行烟气控制所需要研究的重要参数之一,该文通过在缩尺寸试验对侧向集中排烟作用下的烟气逆流行为进行研究,试验发现烟气逆流长度随侧向集中排烟风速增加而衰减得更快,但是以较大的纵向通风风速使烟气逆流长度衰减至火源附近位置时,由于侧向集中排烟产生的横向抽吸力限制了烟气向下游的蔓延运动,导致烟气逆流长度衰减逐渐变缓的现象,揭示了烟气浮力、纵向通风惯性力及侧向集中排烟产生的横向抽吸力三相力的复杂耦合机制。     

纵向通风水平隧道火灾烟气流动特性研究

地铁隧道火灾烟气控制是城市公共安全的一个重要组成部分。在分析地铁隧道火灾烟气流动主要影响因素的基础上，将地铁隧道通风和排烟系统作为一个整体考虑，引入地铁隧道火灾烟气的浮力效应和热阻效应，建立了隧道通风网络火灾模拟的数学模型，分析了地铁隧道火灾烟气逆流的临界条件、临界流速、隧道风流及烟流流速与火灾强度的变化关系，为地铁隧道火灾烟气控制和事故应急处理提供科学依据。     

建筑物走廊型通道中火灾烟气流动特性的研究

对已开发成功的烟流特性预测应用软件进行了改进.应用改进后的软件模拟了走廊型通道在小火荷工况下的烟气流动特性.对比模拟计算数据与实验数据,结果表明二者吻合得比较好,软件实用可靠.     

超声消除电缆火灾烟雾的实验研究

声波团聚技术是利用高强声场的作用使颗粒物发生相对运动从而碰撞并凝聚,大幅减少悬浮的颗粒物。当今城市地下电缆一旦发生火灾将造成巨大的生命及财产损失。在火场应用声波团聚技术能够大幅提高火场的能见度,有助于人员逃生。文章研究了超声场下消除地下电缆火灾烟雾的效果。首先设计了一款频率为18 kHz的气介式换能器,并对其进行模态分析;随后加工了声源,测试其发声效果。结果表明,换能器在开放空间及团聚室内声压级最高分别可达154.1 dB及158.7 dB。开放空间下输入功率越高、越靠近圆盘中心,声压级越高;团聚室内中间监测点处由于壁面及底部反射作用声压级最高。团聚实验结果表明,在声压级为155 dB、初始透光率为8%时,对于液相烟雾及电缆烟雾,分别在5、15 s内透光率达到60%,这表明在超声场下,团聚效果显著,且团聚效果随声压级的增大而增大。     

多层建筑中庭防排烟系统设计

介绍了某多层建筑(商场)中庭防排烟系统的设计，认为此类建筑的中庭应当设置防排烟设施，并有必要对其设置依据、方法、排烟量计算等相关问题开展深入的研究和讨论，制订出相应的规范条文。     

耦合水雾的声团聚消除火灾烟雾的实验研究

对声波耦合水雾消除火灾烟雾的声团聚技术进行了实验研究,并且深入探究了声团聚的作用机理及微观团聚体结构的样貌,通过改变声波频率、声功率、水雾浓度和初始烟雾浓度等参数比较其对消烟效果的影响.结果 表明,声波耦合水雾技术提高了气溶胶分散性,并且水雾产生的液桥力保证了团聚体结构的稳定性,团聚效率得到提高.在初始烟雾浓度为50 ...     

A study on crashes related to visibility obstruction due to fog and smoke

Research on weather effects has focused on snow- or rain-related crashes. However, there is a lack of understanding of crashes that occur during fog or smoke (FS). This study presents a comprehensive examination of FS-related crashes using crash data from Florida between 2003 and 2007. A two-stage research strategy was implemented (1) to examine FS-related crash characteristics with respect to temporal distribution, influential factors and crash types and (2) to estimate the effects of various factors on injury severity given that a FS-related crash has occurred. The morning hours from December to February are the prevalent times for FS-related crashes. Compared to crashes under clear-visibility conditions, FS-related crashes tend to result in more severe injuries and involve more vehicles. Head-on and rear-end crashes are the two most common crash types in terms of crash risk and severity. These crashes were more prevalent on high-speed roads, undivided roads, roads with no sidewalks and two-lane rural roads. Moreover, FS-related crashes were more likely to occur at night without street lighting, leading to more severe injuries.     

大空间内着火位置对火灾增长的影响

以大空间展厅为例,利用火源辐射模型和烟气辐射模型并结合CFAST6．0区域模拟软件的计算结果,对比分析了大空间内不同着火位置下火灾增长的情况。研究结果表明仅考虑火源热辐射的情况下,展厅内着火位置越处于左右中间对称处,其火灾增长越快,热释放速率峰值也越大,达到热释放速率峰值的时间和火灾的持续时间越短,处于展厅中心位置时所有值达峰值。对火源热辐射和烟气辐射综合考虑时,到达热释放速率峰值时间与火灾持续时间的规律同仅考虑火源辐射模型时一致,但热释放速率峰值均有不同程度的提高。     

Measuring reuse in hazard analysis

Hazard analysis for safety-critical systems require sufficient coverage and rigour to instill confidence that the majority of hazardous consequences have been identified. These requirements are commonly met through the use of exhaustive hazard analysis techniques. However, such techniques are time consuming and error-prone. As an attempt at exhaustive coverage, hazard analysts typically employ reuse mechanisms such as copy-and-paste. Unfortunately, if reuse is applied inappropriately there is a risk that the reuse is at the cost of rigour in the analysis. This potential risk to the validity of the analysis is dependent on the nature and amount of reuse applied.This paper investigates hazard analysis reuse over two case studies. Initially reuse in an existing safety argument is described. Argument structures within the hazard analysis are identified and the amount of verbatim reuse examined. A second study is concerned with how reuse changes as a result of tool support. In contrast to the first case, the defined arguments are more diverse—reuse has occurred but is less verbatim in nature. Although tool support has aided the customisation of the reused arguments, many are only trivially customised. An edit distance algorithm is utilised to identify and enumerate verbatim and trivial reuse in the arguments.     

空气净化器检测用的香烟烟雾发生器

香烟烟雾的发生采取正压式,并通过对进入发生器的气体压力和流量进行控制,使得香烟烟雾发生的速度和浓度均是可控的,可以应用于空气净化器洁净空气量(CADR)的检测。     

基于危险分析与风险评价的液压提升机安全设计

介绍了液压提升机的安全性能要求,对液压提升机进行了危险分析和风险评价,确定了各子系统的危险分值,得到了安全设计中必须高度关注的子系统;进行了各子系统的安全可靠度的预计与分配,并简要分析了子系统的安全设计要点,为液压提升机的安全可靠性分析与设计提供了依据。     

A study on the stochastic characteristics of earthquake response spectra in seismic hazard analysis

Abstract

For the purpose of establishing seismic design criteria for engineering structures, it is desirable to assess the expected intensity of seismic strong ground motion at a site for various probability levels (i.e., Seismic Hazard Analysis). In order to consider the seismic hazard at a site, the predictive equations of ground motion are needed. A number of predictive relationships derived from regression analysis of strong‐motion data are available for horizontal peak acceleration, response spectral value, and Fourier amplitude value. Of the earthquake data recorded in the Taiwan area, the “rock site” data are chosen for the determination of ground motion parameters. By using the predictive equation of peak ground acceleration, the seismic hazard curve at a site can be calculated, and by using the model of spectral acceleration attenuation, the uniform hazard spectrum is developed. Finally, by using the proposed Fourier amplitude attenuation model and the mathematical theory of the maximum response of a single‐degree‐of‐freedom linear system, the non‐exceedance probability of the earthquake response spectrum at a site at a certain lifetime can also be developed. Comparisons between the effects of different ground motion parameters on the results of seismic hazard analysis are made.     

Pollution patterns of polycyclic aromatic hydrocarbons in tobacco smoke

Concentrations of polycyclic aromatic hydrocarbons (PAHs) in tobacco smoke of 12 commercial brand cigarettes were determined in a simulated chamber of 20.25 m3 in size. The total concentrations of 17 PAHs (summation operatorPAHs) in the chamber were 3500 and 1152 ng/m3 in vapor phase and particulate phase, respectively. In vapor phase, the yield of naphthalene (NA) appeared to be the most abundant (2462 ng/cig) followed by fluorene (FLUOR) and acenaphthylene (ACY), while the yield of benzo[ghi]perylene (BP) was the most abundant (259.7 ng/cig) in particulate phase followed by phenanthrene (PHEN) and FLUOR. The proportion of PAHs in particulate phase increased with increasing molecular weight. PAHs with two to six rings accounted for 40.2%, 35.3%, 11.7%, 7.6%, 5.2% of summation operatorPAHs, respectively. There was no obvious correlation between PAHs, benzo[a]pyrene (BaP) concentrations in tobacco smoke and smoking tar contents, nicotine contents. With the source fingerprint of PAHs in tobacco smoke, NA could be regarded as the marker of tobacco smoke source because of its largest contribution to summation operatorPAHs (40.2%), followed by FLUOR (12.7%) and ACY (9.8%). Further study indicated that more than 80% of BaP in indoor air of resident homes in Hangzhou was from tobacco smoke.