大气悬浮颗粒PM10对感烟火灾探测器本底效应研究

针对大气污染引起的悬浮颗粒,尤其是可吸入颗粒（PM10）对感烟火灾探测器产生的本底效应进行了分析，并以离子型感烟探测器为例对本底值进行计算，通过比较，显示不同程度的大气颗粒物污染对感烟探测器本底影响的差异极小，排除了感烟探测器在悬浮颗粒污染严重地区发生灵敏度和误报率升高的可能。确认目前各国感烟火灾探测器检测标准对灵敏度指标的规定可以统一，粒子计数等高分辨率颗粒浓度测量技术的发展将使该本底效应的影响不可忽略。     

光电感烟探测器散射特性探讨

本文介绍了一种用于火灾报警的散射型光感烟探测器 ,采用OPTEK公司OP2 31和OP80 1SL光电组合套件作为发射管和接收管。文章重点探讨了两管之间角度变化对探测器灵敏度的影响 ,并对光信号引起的光电三极管的输出进行了估算。     

火灾标准火烟雾颗粒测量及粒径尺度分布函数研究

烟雾是火灾探测的重要参量，烟雾颗粒粒径及其尺度分布直接影响到感烟探测器的灵敏度，而目前有关烟雾颗粒粒径的研究相当匮乏。采用扫描迁移率粒子测量仪对火灾标准火烟雾颗粒的粒径大小及其分布进行实验测量，并采用数学拟合方法系统研究了烟雾颗粒粒径分布函数，研究结果表明对数正态分布函数较好地描述了烟雾颗粒尺度分布特征，其结论有益于火灾探测基础研究的发展。     

地铁大纵深空间的火灾探测器选型研究

城市轨道交通中车辆段、停车场内设运用库,此类大纵深建筑空间,存在火灾探测的难度。本文以运用库为背景,对两种非常规火灾探测器一一红外线型光束感烟探测器、吸气式感烟探测器的原理及特点进行分析说明。     

基于微控制器2051实现的探测器设计

本文探讨一种智能型火灾探测器的设计过程。通过对火灾报警控制器配套的光电感烟火灾探测器的设计。探讨利用AT89C2051微处理器芯片完成信息的探测、多地址信息的发送控制及分析、判断、报警等功能。     

基于微控制器2051实现的探测器设计

本文探讨一种智能型火灾探测器的设计过程.通过对火灾报警控制器配套的光电感烟火灾探测器的设计.探讨利用AT89C2051微处理器芯片完成信息的探测、多地址信息的发送控制及分析、判断、报警等功能.     

不同流量对催化裂化烟气轮机内部气-固两相流动的影响

基于欧拉-拉格朗日模型,对催化裂化烟气轮机内部气固流动特性进行数值研究;采用可压缩流体的k-ε双方程湍流模型,分析2种入口烟气流量对催化裂化烟气轮机内部流场及颗粒运动的影响。结果表明,随着流量的增大,静叶流道内静压、静温、分子黏度、动叶出口截面的气流速度有增大的趋势,颗粒的运动轨迹呈现向动叶叶片靠近的趋势,颗粒浓度在叶片上的分布呈增大的趋势,颗粒沉积速率较大的区域范围呈扩大的趋势。     

烟气轮机内不同粒径颗粒运动规律的数值研究

基于欧拉-拉格朗日模型,对催化裂化烟气轮机内部气固两相流动特性进行数值研究;采用k-ε湍流模型和离散相模型对不同粒径颗粒在烟气轮机内的运行规律进行模拟。结果表明:烟气流道内气相速度和压力的分布是导致固相颗粒与叶片表面发生碰撞和沉积的主导因素;在动叶压力面内,粒径大于5μm的颗粒更容易与叶片表面发生碰撞,且随着粒径的增大颗粒更倾向于和叶片底部发生碰撞。     

细水雾作用下烟颗粒形貌及尺寸变化规律研究

利用Sirion200型场发射扫描电子显微镜拍摄细水雾作用前后柴油和聚氯乙烯(PVC)材料烟颗粒的形貌和内部结构图像。定义了烟颗粒的采样平均直径(dA)和表面密度(ρS),利用统计分析的方法计算了细水雾作用前后烟颗粒的dA和ρS,研究了采样点空间位置、细水雾工作压力、雾滴粒径和雾滴速度等因素对dA和ρS的影响规律,揭示了细水雾冲刷火灾烟颗粒的主导机理,为细水雾技术用于计算机房等电气环境的火灾烟气抑制提供了科学的参考依据。     

高温气冷堆蒸气发生器结构内石墨粉尘的运动行为

为研究高温气冷堆石墨粉尘的运动规律,采用数值模拟的方法,分析高温气冷堆一回路蒸气发生器由于特殊的结构特点对石墨粉尘颗粒沉积扩散特性带来的影响。数值模拟结果表明:蒸气发生器的结构特点造成的石墨粉尘沉积主要集中在外套壁面、中心管壁面与第一道换热管的迎风管壁上;在颗粒粒径确定的情况下,其沉积的效率随气流速度的增大而相应增大;在一定的气流进口速度下,颗粒沉积率随颗粒粒径的增大而增大。     

Gamma-Free Smoke and Particle Detector Using Tritiated Foils

A smoke and particle ionization detector using tritiated amorphous silicon film as the radiation source is demonstrated. The ion chamber design includes both bipolar and unipolar regions, thereby enhancing the particle detection responsivity. The results show that this gamma-free detector is several-fold to fortyfold more responsive than traditional ionization detectors using Am-241. In addition, this ion chamber can function as a dual detector having both photoelectric and ionization detector responsivities     

结构化流道近壁区软性磨粒流流动仿真及实验研究

为了揭示结构化流道近壁区软性磨粒流的压力场及速度场的分布规律,有效预测其软性磨粒流的材料去除特性,采用VOF多相流模型和RNG 湍流模型,通过对结构化流道的结构进行合理的网格划分和特殊边界条件设置,对结构化流道内部的软性磨粒流流动进行数值模拟。仿真结果表明：不同的软性磨粒流入口位置对工件加工会产生影响;结构化流道中软性磨粒流的压力场、速度场和软性磨粒流的去除率随着加工区域位置的不同而不同;加工区域入口区域的压力、速度值存在突变,为此在实际加工用引入了引流模块。流场数值模拟和实验研究结果趋势是一致的,数值模拟为深入研究软性磨粒流的基本规律提供一种理论工具     

双四象限光电探测器在线测试虚拟仪器

通过监测与所接收的激光弥散斑相对应的输出信号的变化率可以对探测器进行实时非接触测量,从而实现以双四象限探测器为接收器件的产品的在线检测和质量控制。介绍了以Labwindows/CVI为开发平台的双四象限探测器的测试、分析系统。建立了探测器接收弥散斑与输出信号变化率的关系模型,采用三次样条插值函数提高欠采样时ns级极窄光电脉冲信号峰值的求取精度。通过实验得到了探测器接收弥散斑与光敏面直径的最佳比值为0.5。研究结果表明,弥散斑直径测量的分辨力为0.0096mm,峰值电压测量幅值分辨力0.1mV。     

一种基于多传感器信息融合的火灾探测系统

根据火灾的特征与燃烧产物,设计了一种基于多传感器信息融合的火灾探测系统.该系统以DSP TMS320LF2407A为处理器,包括一氧化碳传感器模块、温度传感器模块和紫外火焰传感器模块.紫外火焰传感器可以很好地区分闪燃火和阴燃火,一氧化碳传感器和温度传感器能够对闪燃火和阴燃火产生不同的反应,因此系统采用两种不同的算法来探测闪燃火和阴燃火.该火灾探测系统在燃烧室中通过了实验验证.实验表明,该火灾探测系统比通用的感烟型探测器具有更快的探测速度和准确度,且不会在常见干扰源的干扰下产生误报警.     

The analysis of the transmission-type optical smoke detector threshold sensitivity to the high rate temperature variations

Reliability of the transmission-type optical smoke detectors is limited by the high sensitivity of optical components to parasitic effects, especially to contamination and temperature. Influences of the high rate temperature variations cannot be eliminated by filtering, as their spectral range partially overlaps with the spectral range of a smoke absorption index. Hence, sensitivity to these effects has to be eliminated through the mutual cancellation of the corresponding components of the output signal. First determining the temperature dependence of the light source and the receiver in the generalized block diagram of the transmission-type optical smoke detector, transfer functions are derived, specifying the detector output signal as a function of the temperature variations of the blocks considered. Using the second-order thermal model for the thermal system of the optoelectronic diodes, an expression is given for the steady-state solution of the difference of the source and the receiver diode junction temperatures, when the ambient temperature is a ramp function of time. On the basis of the thermal system analysis, a block diagram is shown to be equivalent to RC low-pass (LP) filters that model the pn junction temperature dependence on ambient temperature. For the completed block diagram, with the help of the expressions derived, an analysis is performed to establish how to eliminate the detector threshold sensitivity to ambient temperature variations, or to adjust it to realize a multicriteria fire detector.     

Performance of a three-element thin film detector

A nuclear charged particle detector has been designed and fabricated at the University of Florida for use in identifying the nuclear charge Z and mass number A of low energy (1 MeV/amu) heavy mass ions. The detector consists of a stack of three sequential thin film detectors (made from NE-102A plastic scintillator) for three successive measurements of the specific luminescence ΔL/Δx and velocity of a transiting ion and a terminal surface barrier detector for measuring the ion residual energy. This detector assembly was tested by measuring its response to various isotopes of germanium and selenium ions accelerated to selected energies between 53 and 169 MeV and then scattered from a thin gold target foil. The tests were performed to obtain quantitative information on the ability of the detector system to identify the nuclear Z of an impinging ion and to test the 0810 1076 V 3 advantage of having three successive measurements of ΔL/Δx from three sequential and independent thin film detectors. It was determined that below 2 MeV/amu the detector response was dependent on particle velocity but independent of particle mass and below about 0.9 MeV/amu the detector was not able to distinguish between ions having two units difference in Z, probably due to similarities in ionic charge state distributions. It was also determined that the use of three detectors reduced the FWHM of the TFD response by 54%.     

Evaluation of the design requirements for the electrical part oftransmission-type optical smoke detector to improve its thresholdstability to slowly varying influences

The output signal sensitivity to optical component contamination and other slowly varying parasitic influences in the transmission-type smoke detector is analyzed. The analysis carried out the new topology characterized by the selective feedback loop incorporating the optical part of the detector. Depending on the loop gain frequency shaping in the electrical part of the loop, dual-stability enhancement of the input threshold level can be achieved. The stable dc output signal can be preserved by the high dc loop gain value, as an option to the standard serial filter dc rejection. The detector passband gain stability is achieved by the high loop gain selectivity, eliminating feedback at very low or passband frequencies. The proposed topology can be easily adopted to both digital and low-cost analog detector designs. The special case of the threshold sensitivity neutralization through the cancellation of the output dc signal sensitivity and passband gain sensitivity is considered, too, as an option suitable for low-cost detectors. In addition to the described linear settlement, two nonlinear solutions are presented, the first of them based on the foregoing linear circuit analysis. Despite its nonlinear nature, this alternative solution is not troublesome for analog implementation, since the nonlinear function required is realized by the standard variable gain amplifier. Another nonlinear method requires logarithmic function implementation, so that its suitability depends on the particular design requirements     

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。