DL／T868—2004与JB4708—2000的比较分析

本文通过对DIJT868—2004《焊接工艺评定规程》和JB4708—2000《钢制压力容器焊接工艺评定》的比较分析,指出了两者的主要共性和差异,阐明了统一承压类特种设备焊接工艺评定标准的必要性。     

M—B／DS电梯事故分析

（1）事故基本情况 2007年6月赤峰市某发电厂1#机组电梯发生溜车事故，电梯冲顶后又反向轧车使轿厢产生变形，未造成重大人员伤亡。     

SZL15—1．6／350-AⅡ／Q锅炉过热器爆管原因分析和解决措施

对煤、气混烧锅炉过热器爆管事故进行原因分析，并提出了解决和预防措施。     

GB／T23465—2009《呼吸防护用品实用性能评价》简要

本文介绍了GB／T23465-2009《呼吸防护用品实用性能评价》的主要技术内容及其依据,以帮助相关人员理解与应用该标准。     

75帧／秒准高帧频CCD摄像机—74HO特性分析

本文介绍了准高帧频CCD摄像机的一般概念及75帧/秒CCD摄像机输出图像的工作原理和主要性能指标,说明了其优点和应用前景。     

GB／T20097—2006《防护服一般要求》简介

防护服是保护从业人员在生产和工作中减轻职业伤害的必要防护装备。防护服装的品种设置、质量要求、使用方法等直接关系到防护服装的防护效能。为使大家进一步了解、执行GB／T20097-2006《防护服一般要求》,本文结合防护服的国内外现状。介绍该标准的产生背景和主要内容。     

SHL15—1．25／370型锅炉过热器爆管事故分析及整改措施

1前言 北京航空材料研究院动力部为解决生产电力供应不足问题,在供暖锅炉房内安装了一台1500kW凝汽式热电联产机组。锅炉选用SHL15—1．25／370-Am型,它既能满足汽轮发电机组1500kW发电量所需要的热能,同时又能满足我院科研生产区供暖的热量。由于该机组是以热定电,     

基于C/S/S+B/W/S/S混合模型安全系统的分析与设计

随着信息系统规模的不断扩大和互联网技术的发展,多层体系结构B/W/S/S,C/S/S应运而生,在综合分析了B/W/S/S结构和C/S/S结构的基础上,以C/S/S结构为系统管理核心,由网络管理服务集、网络管理协议平台组成了一种B/W/S/S,C/S/S混合结构信息系统模式。为解决该混合结构信息系统的安全性问题,笔者提出了将防火墙和强用户认证机制相结合的方案。由于防火墙的主要防范目标是来自于外部网络的攻击,对于自己内部网络却基本上不采取什么安全措施。当内网用户远程登录系统时,通过强身份认证系统进行有效的身份验证,可以补充防火墙在安全防范方面的不足,有效地保障了网络信息系统的安全性。     

聚碳酸酯/ABS/蒙脱土纳米复合材料的热重动力学分析

利用直接熔融插层技术制备聚碳酸酯/ABS聚合物合金/蒙脱土纳米复合材料.用热重分析法(TGA)研究了聚合物合金和纳米复合材料的热氧化降解行为.分别采用了无模式函数法(model-freemethod)和多元非线性回归法(multivariate nonlinearregression method)进行动力学评价.由此确定了整个降解过程的表观动力学参数.研究结果表明聚碳酸酯/ABS/蒙脱土纳米复合材料具有较高的热稳定性和阻燃性.两种材料的热氧化降解模型是一个两步分解过程.     

EVA树脂粉尘/甲烷/空气杂混物爆炸特性

在20 L爆炸实验装置中,开展了3种不同中值粒径的EVA树脂粉尘/甲烷/空气所组成的杂混物爆炸特性研究,探究了甲烷浓度对粉尘爆炸下限、最大爆炸压力的影响。结果表明,尽管添加的甲烷气体浓度低于爆炸下限,仍使得粉尘爆炸下限得以降低,粒径较大的EVA III粉尘,当甲烷体积分数为1%时,爆炸下限降低约25%;粒径较小的EVA I粉尘,当混入甲烷体积分数为4%时,爆炸下限则降低80%;甲烷体积分数每增加1%,可燃粉尘最大爆炸压力上升约10%,但对于粒径较小的EVA I粉尘,当甲烷体积分数为4%时,最大爆炸压力的上升呈现突变趋势,上升近50%。     

The explosion overpressure field and flame propagation of methane/air and methane/coal dust/air mixtures

The explosion of the methane/air mixture and the methane/coal dust/air mixture under 40 J center spark ignition condition was experimentally studied in a large-scale system of 10 m³ vessel. Five pressure sensors were arranged in space with different distances from the ignition point. A high-speed camera system was used to record the growth of the flame. The maximum overpressure of the methane/air mixture appeared at 0.75 m away from the ignition point; the thickness of the flame was about 10 mm and the propagation speed of the flame fluctuated around 2.5 m/s with the methane concentration of 9.5%. The maximum overpressure of the methane/coal dust/air mixture appeared at 0.5 m. The flame had a structure of three concentric zones from outside were the red zone, the yellow illuminating zone and the bright white illuminating zone respectively; the thickness and the propagation speed of the flame increased gradually, the thickness of red zone and yellow illuminating zone reached 3.5 cm and 1 cm, the speed reached 9.2 m/s at 28 ms.     

铜铁共掺杂TiO2/膨润土光催化剂的制备及光催化性能

以溶胶-凝胶法、液相沉淀法和机械混合法制备了Cu-Fe双金属掺杂的TiO2/膨润土复合光催化剂,采用XRD、FTIR对其进行了结构表征,以紫外光和可见光催化降解直接天蓝染料废水为模型,考察了制备方法对催化剂光催化性能的影响。结果表明:各催化剂中均有锐钛矿型TiO2生成,且部分TiO2进入了膨润土的蒙脱石层间,改变了其层间的有序性,生成了Ti—O—Si键,实现了TiO2粒子与膨润土的复合。溶胶-凝胶法制备的催化剂中TiO2与膨润土的复合程度最高,Cu2+和Fe3+成功掺入了TiO2晶格,形成了复合半导体,拓宽了TiO2的光谱响应范围,使该催化剂表现出最优的光催化活性,并且该催化剂性能稳定,易于沉降分离,经高温活化再生后仍具有良好的催化活性,可重复多次使用,表现出良好的再生性能。     

Flash point of biodiesel/glycerol/alcohol mixtures for safe processing and storage

Mixtures of biodiesel, glycerol, and ethanol/methanol are commonly processed and stored in biodiesel production. In this work, non-ideal models are used to calculate the Flash Points (FPs) of binary and ternary mixtures, using data available from different feedstocks. Despite the fact that biodiesel is considered safer than common diesel fuels, results show a synergistic effect of biodiesel/methanol and biodiesel/ethanol mixtures, resulting in a reduction of the flash point of mixtures to values lower than the ones of pure compounds. Most soluble ternary mixtures were found flammable, the only exception being mixtures with a relatively lower alcohol content (45% mol. ethanol or 42% methanol) at temperature lower than 303 K. Accidental increase in temperature can cause domino effect, due to the higher solubility and the formation of new flammable ternary mixtures.     

台湾康讯GPS/GSM/GPRS车辆监控系统

1 系统组成 康讯GPS/GSM/GPRS车辆监控系统分为车载终端子系统和监控中心子系统两部分. 1.1车载终端子系统 车载终端子系统由IntelliTrac X8车台、显示屏和电话手柄等组成.     

铝粉超细化对KClO3/Al/S配方药剂特性的影响

为研究铝粉超细化后对烟火药剂性能的影响,将普通铝粉和纳米铝粉分别与氯酸钾、硫黄粉按照零氧平衡的同一配比(17%Al+63%KClO3+20%S)配制成烟火药剂,分别用0#样品和1#样品表示。用ARC、WL-1型落锤仪和MGY-1型摆式摩擦感度仪等试验装置从热安全性、撞击感度和摩擦感度等方面进行对比试验。结果表明,与含普通铝粉的0#样品相比,含纳米铝粉的1#烟火药剂热分解的初始反应温度明显降低(118.67℃<123.3℃),反应到达最大温升速率所需的时间明显延长(4.94min>0.13 min),反应所能达到的最高压力明显降低(2.77 MPa/g<3.14 MPa/g),反应动力学因子明显降低(361.85 kJ/mol<409.41 kJ/mol),撞击感度明显下降(12%<100%)。这说明铝粉粒径对药剂的性能有一定的影响。纳米铝粉的加入在加速烟火药剂反应进程的同时,可有效降低其反应的激烈程度、压力危险性和撞击危险性,即铝粉超细化后可以有效改善烟火药剂的性能,提高其安全性。     

Experimental investigation on the lower flammability limits of diethyl ether/ n-pentane/epoxypropane-air mixtures

Diethyl ether (DEE), epoxypropane (PO) and n-pentane have excellent ignition and combustion performance; hence, they have a wide variety of applications in industry and advanced aviation propulsion systems. As these fuels are flammable at normal temperature and pressure, their explosive characteristics need to be explored. In this study, the lower flammability limits (LFLs) of vapor mixtures of DEE/PO/n-pentane in air were measured in 20 L, closed, stainless steel spherical vessels. Experimental results were obtained at ambient atmospheric pressure and an initial temperature of 40 °C. The experimental results show that the LFLs of DEE-air, n-pentane -air, and PO-air are 1.81 vol%, 1.41 vol% and 2.44 vol%, respectively. The LFLs of binary/ternary fuel mixtures under different compositions were tested, and the experimental results are compared with the classical Le Chatelier's formula. The results show that, for the binary fuels (i.e., DEE/PO, DEE/n-pentane, PO/n-pentane)-air mixtures, the maximum difference of the LFLs between Le Chatelier's formula and the experimental results is 6.10%. For the ternary fuels (i.e., DEE/PO/n-pentane)-air mixtures, the maximum difference of the LFLs between the two results is 6.33%. Due to the adiabatic flame temperature of each single fuel mixture being close, the Le Chatelier's formula is applicable for an estimation of the LFL for DEE/PO/n-pentane-air mixtures.     

Numerical studies on minimum ignition energies in methane/air and iso-octane/air mixtures

In this study, the dependence of minimum ignition energies (MIE) on ignition geometry, ignition source radius and mixture composition is investigated numerically for methane/air and iso-octane/air mixtures. Methane and iso-octane are both important hydrocarbon fuels, but differ strongly with respect to their Lewis numbers. Lean iso-octane air mixtures have particularly large Lewis numbers. The results show that within the flammability limits, the MIE for both mixtures stays almost constant, and increases rapidly at the limits. The MIEs for both fuels are also similar within the flammability limits. Furthermore, the MIEs of iso-octane/air mixtures with a small spherical ignition source increase rapidly for lean mixtures. Here the Lewis number is above unity, and thus, the flame may quench because of flame curvature effects. The observations show a distinct difference between ignition and flame propagation for iso-octane. The minimum energy required for initiating a successful flame propagation can be considerably higher than that required for initiating an ignition in the ignition volume. For iso-octane with a small spherical ignition source, this effect was observed at all equivalence ratios. For iso-octane with cylindrical ignition sources, the phenomenon appeared at lower equivalence ratios only, where the mixture's Lewis number is large. For methane fuel, the effect was negligible. The results highlight the significance of molecular transport properties on the decision whether or not an ignitable mixture can evolve into a propagating flame.