CO_2分析在含化学添加剂的细水雾灭火研究中的应用探讨

通过实验和计算证明CO2浓度分析是评价含添加剂细水雾灭火有效性的简单而有效方法。采用燃烧分析仪测定细水雾灭火实验过程中的CO2浓度,比较含不同添加剂细水雾和纯水细水雾在同一实验控制条件下的CO2浓度变化规律,利用CO2浓度变化规律判断含添加剂细水雾灭火的效率。根据上述规律,可从两方面比较细水雾的灭火效率:一是CO2的最高浓度。CO2达到的最大浓度小,则燃烧过程中的热释速率小或灭火时间短,说明细水雾抑制燃烧的效果较好。二是施加细水雾后CO2浓度变化率。CO2浓度变化率小,燃烧过程中的热释速率就小,说明细水雾抑制燃烧的效果较好。     

纳米SiO2和发泡剂对聚氨酯防火涂料阻燃性能的影响

近几年来我国火灾的严重性已使木材阻燃成为一项紧迫任务.为了提高马尾松胶合板的阻燃性能,以聚氨酯为对象,采用HRR3热释放率系统、HC-2氧指数测定仪等测定了涂覆膨胀型纳米聚氨酯防火涂料的马尾松胶合板的燃烧热释放率和氧指数,分析了纳米SiO2以及各种发泡剂对聚氨酯防火涂料阻燃性能的影响,并分析它们的阻燃机理.结果表明,在聚氨酯防火涂料中加入纳米SiO2,可使涂覆的胶合板燃烧失重和炭化体积明显降低,有效地提高阻燃性能,纳米SiO2用量以3%为宜.加入发泡剂可进一步提高涂料的阻燃效果和氧指数值.复合发泡剂比单一发泡剂效果好.在8种试验方案中,用尿素-双氰胺按1∶3的质量比组成的复合发泡剂阻燃效果最优,在HRR3热释放率系统测试中,涂覆的胶合板着火燃烧时间最长(69 s),达最高热释放率时间最短(130 s),热释放率峰值最低(53.45 kW/m2),氧指数值最高(55).     

基于高压水射流分布特性的清洗参数选择

针对高压水射流清洗参数选择简单盲目的问题 ,通过高压水射流动压和流量分布特性以及水射流清洗机理的分析 ,揭示了水射流清洗过程中存在的水射流冲击压力、持续作用时间和能量散布等临界条件要求 ,明确了从工艺参数选择、射流分布特征到清洗效能之间的相关关系 ,为清洗过程分析提供理论依据 ;并基于临界动压与高压水射流动压分布规律 ,推导了最佳靶距和最大清洗宽度估算公式 ;对清洗工作压力、入射角度、清洗靶距、横移速度等清洗工艺参数的选择进行了分析 ;简化并优化了清洗参数选择方法。     

火灾场景设计与火灾危险度分析在火灾性能化设计危险源辨识中的应用

通过介绍设定火灾场景,计算热释放速率,使用火灾危险度的概念对建筑火灾的危险性进行综合评价等方法,探讨了在性能化防火设计中的危险源辨识问题。给出了一个对某航站楼进行面向性能化设计的火灾危险评估的工程算例。     

性能化防火设计中的火灾危险源分析及设定火灾

火灾危险源分析和设定火灾是进行性能化防火设计的基础也是一个十分重要的环节。客观地对火灾危险源进行辨识与分析,准确地设定火灾并选取合适的火灾热释放速率随时间变化的曲线,才能使得整个性能化防火设计达到预期的目标。通过结合实例介绍了危险源分析经常遇到的两种情况和典型的四种设定火灾类型,以及它们各自的分析计算方法。     

太湖内源释放及营养盐输运研究

从对流-扩散方程出发,通过公式推导,建立了包含底泥污染的水流-水质模型,对模型进行了率定和验证后,应用于太湖.该模型将湖泊水相和内源悬移相污染作为一个整体,结合污染物在悬移泥沙上的各种迁移过程,研究了太湖总氮、总磷内源释放的分布和数量,过程中考虑了悬移泥沙的各种影响因素,得到了较理想的模拟结果,当风速≤3.5 m/s时,冲刷和悬移造成的内源污染物释放量较小,内源污染物释放主要通过泥-水界面的静态释放;当风速>3.5 m/s时,冲刷和悬移造成的内源污染物释放量随风速增加迅速增大.通过计算得出2001年太湖内源释放的总氮为3.0万t,总磷为0.8万t.     

Incorporating the 2007 recommendations of the International Commission on Radiation Protection into the J-value analysis of nuclear safety systems

The newly released findings by the International Commission on Radiation Protection (ICRP) led to a review of the lifetime risk coefficients for fatal cancer used in J-value analysis of nuclear safety systems. The change in life expectancy a safety system brings about by averting a radiation exposure needs to be estimated in order to calculate the safety system's J-value, and this is done following the ICRP's practice of using risk coefficients that are uniform across both genders and all ages in the defined population group (either workers or the general population). The ICRP predicted uniformly lower radiation risks in 2007 than in 1990 on a like-for-like basis, but it was found that the ICRP's new risk coefficients needed to be multiplied by a compensating factor specific to each population when used in calculating the radiation-induced change in life expectancy. Incorporating the new compensating factor leads to a decrease in the J-value calculated of about 5% for workers and 15% for the general population compared with earlier, reported results. These adjustments are not large compared with the uncertainties associated with radiation harm and the economics of installing a safety system, but will strengthen slightly the case for spending on a nuclear safety measure.     

转基因生物环境释放风险评估的原则和一般模式

风险评估是转基因生物环境释放依法管理的一项重要内容 ,也是生物安全研究的核心内容之一。本文在分析和比较国内外有关转基因生物风险评估方法的基础上 ,结合作者近年来对转基因生物风险评估的专题研究 ,对转基因生物环境释放风险评估的基本原则和一般模式进行了全面的描述。这种模式一般包括危险识别、风险估算和风险评价 3个连续过程 ,并可分解为 7个具体步骤     

Microwave treatment of dairy manure for resource recovery: Reaction kinetics and energy analysis

A newly designed continuous-flow 915 MHz microwave wastewater treatment system was used to demonstrate the effectiveness of the microwave enhanced advanced oxidation process (MW/H₂O₂-AOP) for treating dairy manure. After the treatment, about 84% of total phosphorus and 45% of total chemical oxygen demand were solubilized with the highest H₂O₂ dosage (0.4% H₂O₂ per %TS). The reaction kinetics of soluble chemical oxygen demand revealed activation energy to be in the range of 5–22 kJ mole^?1. The energy required by the processes was approximately 0.16 kWh per liter of dairy manure heated. A higher H₂O₂ dosage used in the system had a better process performance in terms of solids solubilization, reaction kinetics, and energy consumption. Cost-benefit analysis for a farm-scale MW/H₂O₂-AOP treatment system was also presented. The results obtained from this study would provide the basic knowledge for designing an effective farm-scale dairy manure treatment system.     

A COMPARISON OF SOME DYNAMIC,LINEAR AND POLICY ITERATION METHODS FOR RESERVOIR OPERATION1

Within the past few years, a number of papers have been published in which stochastic mathematical programming models, incorporating first order Markov chains, have been used to derive alternative sequential operating policies for a multiple purpose reservoir. This paper attempts to review and compare three such mathematical modeling and solution techniques, namely dynamic programming, policy iteration, and linear programming. It is assumed that the flows into the reservoir are serially correlated stochastic quantities. The design parameters are assumed fixed, i.e., the reservoir capacity and the storage and release targets, if any, are predetermined. The models are discrete since the continuous variables of time, volume, and flow are approximated by discrete units. The problem is to derive an optimal operating policy. Such a policy defines the reservoir release as a function of the current storage volume and inflow. The form of the solution and some of the advantages, limitations and computational efficiencies of each of the models and their algorithms are compared using a simplified numerical example.