Computer simulation of combustion of mine fires

According to control theories, mine fires can be considered as an unsteady process after the normal ventilation system is disturbed. Applied the principal of physical chemistry and thermal fluid mechanics, the parameters models of the unsteady state system have been given, such as fuel combustion rate, heat of combustion, concentration, temperature, heat losses, heat resistance, work of expansion and heat pressure difference. The results of the calculation agree approximately with the results of the test. By the computer simulation, it is shown that the main factor of producing the throttling effect is the fire rate, second is the heat resistance and the heat pressure difference. The rate of heat flow that passes through the airway wall is the maximum on the surface, and decrease with time. The heat transfer progresses only within the range of 0..5 m away from theairway wall during combus-tion for 2 hours. It‘s variable for the mass flux rate and the percentage concentration of the gas along the airway of the downstream. When the delayed time is very small, the varidtion can be neglected. Viscosity resistance is the main part of the heat resistance, second is the expansion resistance that is less than tens Pascal when Mach number is very small. Work of expansion is principally tumed into heat losses, only a very small part is consumed by the work of the heat resistance and the inertia acceleration.     

正视经济发展过程中的火灾问题

1 引言近年来,我国连续发生多起特大和重大火灾。这不仅在我国引起很大的震动,在世界上也产生了强烈的反响。迅速采取有效措施,扼制火灾上升的势头,已成为党、政府和全国人民普遍关心的问题。     

静电加速器中输电带张力与转速的最佳关系

采用输电带的静电加速器运行时,一般通过调节输电带张力来减小输电带的抖动。本工作采用一个简化的计算模型,导出输电带在运行过程中发生抖动的基本规律。结果表明：输电带张力、输电带所带电荷密度和输电带的转速间存在一使输电带抖动最小的最佳关系。     

烟雾浓度及粒径的激光探测实验研究

烟雾是火灾的前兆和伴随产物,是火灾过程中的重要物理现象。烟雾浓度和平均粒径是烟雾的两个重要特性参数,是早期火灾探测的基础。本文对激光与烟雾相互作用进行了具体分析,提出了一种基于激光消光法和角散射法,同时探测烟雾的浓度和平均粒径的方法。本方法可用来进行早期火灾的探测报警,能克服传统的光电感烟探测技术存在的缺点,大大提高火灾探测的可靠性和灵敏度。     

细水雾与射流卷吸现象的LDV/APV测量研究

本文利用三维激光多普勒测 计和自适性相位移普勒速度计系统（三维ＬＤＶ／ＡＰＶ系统）,通过观察和测量细水雾被射郑吸的现象,获取了细水雾的平均速度,平均粒径和雾能量等特性参数,深化认识细水雾被射流卷吸的机理,为下一步进行细水雾被火焰卷吸现象的实验研究打下了良好的基础。     

聚丙烯酰胺/氧化石墨纳米复合材料的研究

氧化石墨具有良好的层状结构,其层间具有丰富的官能团,能与有机聚合物形成插层纳米复合材料进而改善材料的性能．采用层离吸收-原位聚合法制备了聚丙烯酰胺／氧化石墨纳米复合材料,并采用XRD、HREM及DSC等对其结构和性能进行了表征。结果表明,聚丙烯酰胺与氧化石墨两者之间存在着较强的相互作用,材料的玻璃化转变温度得到提高,层离吸收-原位聚合法是获得聚丙烯酰胺／氧化石墨层纳米复合材料的有效途径,聚丙烯酰胺在氧化石墨中存在着多种排列方式,不同层间距(1．6nm和2．8nm)的聚丙烯酰胺／氧化石墨纳米复合结构同时存在。     

CAN总线在现场总线控制系统中的应用

本文通过介绍CAN（Controller Area Network，控制器局域网）总线技术在FCS（Fieldbus Control System现场总线控制系统）中的应用，阐述了CAN总线设备的设计与实现，并简要说明了如何基于CAN总线来 设计现场总线控制系统。     

核动力装置安全壳内氢气扩散传播过程的三维非定常数值模拟

研究了对核能系统火灾安全具有重要意义的核动力装置安全壳内氢气的扩散传播过程，采用圆柱坐标下的三维非稳态数学模型研究了含阻挡物的半圆柱体密闭壳体下部氢气在浮力作用下的运动过程。     

Synthesis and characterization of poly acrylic acid/graphite oxide nanocomposite

1　INTRODUCTIONOrganic intercalatedlayeredsolidshavebeenstudiedbyscientistsindifferentfieldsformanyyearsbecauseoftheirnew physicalandchemicalpropertiessuchaselectricalproperties[1] ,mechanicalproper ties ,thermalbehavior[2 ] ,surfaceandinterfacialproperties[3] .Graphiteoxide (GO)hasbeenstudiedformany years ,itsstructuralmodel[4 6 ] ,formationprocessandkinetics[7,8] havebeenstudiedindetail.IthasbeenreportedthatGOpossessesC OHande poxidefunctionalgroups[9] whichmakegraphiteox ideeasilyabs…