环境温度及水平安装位置对感烟型火灾探测器响应性能影响的研究

用FDS软件研究了环境温度和水平安装位置对感烟型火灾探测器报警时间的影响.通过在水平方向上设置多组感烟型火灾探测器,对比分析了0℃、10℃、30℃的环境温度下,不同位置感烟探测器报警时间的差异和规律性.研究表明:主要受火源正上方羽流烟气和远端壁面回流烟气影响的探测器的报警时间随环境温度的升高有提早报警的趋势;主要受近端壁面回流烟气影响的探测器的报警时间随环境温度的升高有滞后报警的趋势;三个环境温度下位于火源正上方羽流中心的探测器的报警时间最早,且报警时间相同.     

井下火灾中逃生人员健康度评价模型

在井下火灾逃生过程中,矿井人员在有害环境影响下的身体状况对其逃生的成功与否具有决定性作用。提出了井下火灾中逃生人员健康度的概念,综合分析了热辐射、有毒气体、烟尘颗粒及缺氧等危害因素对井下人员健康度的影响。基于模糊综合评价方法,建立了上述危害因素对逃生人员健康度的影响评价模型,并建立了人员在逃生过程中的健康度的动态评价方法。利用火灾模拟软件FDS对井下火灾实例进行了简单模拟,模拟结果验证了该评价方法的实用性和有效性。人员健康度能够对复杂灾害环境中的逃生人员状态进行综合评价,为井下灾害中的逃生路径决策提供量化的标准。     

Credit card fraud detection: A fusion approach using Dempster–Shafer theory and Bayesian learning

We propose a novel approach for credit card fraud detection, which combines evidences from current as well as past behavior. The fraud detection system (FDS) consists of four components, namely, rule-based filter, Dempster–Shafer adder, transaction history database and Bayesian learner. In the rule-based component, we determine the suspicion level of each incoming transaction based on the extent of its deviation from good pattern. Dempster–Shafer’s theory is used to combine multiple such evidences and an initial belief is computed. The transaction is classified as normal, abnormal or suspicious depending on this initial belief. Once a transaction is found to be suspicious, belief is further strengthened or weakened according to its similarity with fraudulent or genuine transaction history using Bayesian learning. Extensive simulation with stochastic models shows that fusion of different evidences has a very high positive impact on the performance of a credit card fraud detection system as compared to other methods.     

火灾救援系统中动态定位方法研究

火灾救援系统的一个关键问题是救护人员的标识及其位置的实时获取;现有大多数定位系统需要特殊硬件的支撑,这样会加大系统开销;另外,已有的定位算法大都假设消防员是静止的或者事先布置的GPS点是定位的,这些都不符合实际的需求;文章给出了一个新的定位方法,该方法在消防队员和部分带有GPS的队员间通过通信来获取自己的估计位置,从而当消防员受到危险情况时,可以在第一时间得到救助。并且避免所有消防员都配戴GPS,有效地降低了系统成本。     

三端柔性多状态开关运行控制与示范应用

分布式能源的广泛接入可能会导致诸如配电网电压越限和网络堵塞等多种问题。柔性多状态开关（flexible distribution multi-state switch, FDS）是一种调节能力强、控制灵活性高的新型电力电子设备,可以有效解决间歇性分布式电源（distributed generators, DGs）高比例接入所引起的一系列问题。三端柔性多状态开关可以更安全、可靠和快速地调节系统潮流,通过对有功功率和无功功率的快速、精准控制,进一步实现馈线之间的柔性互联,从而改善系统电压水平,提高供电可靠性。介绍了广东佛山柔性多状态开关示范工程的基本情况,提出含柔性多状态开关的配电网故障自愈控制策略,建立含柔性多状态开关的配电网运行优化和自愈控制的统一模型,并在示范工程实际算例上分析了柔性多状态开关对改善配电网运行状态的作用。结果表明,柔性多状态开关的应用可以有效地改善配电网电压分布,同时提高供电可靠性。     

一维高阶ENO格式的应用研究

构造了基本ENO有限体积格式，在标量守恒系，矢量守恒系中研究了ENO格式的具体应用，给出了矢量守恒系中基于特征分量的ENO重构算法，通过采用Roe平均通量差分分裂(Roe-FDS)，有效地抑制了间断解附近的振荡。一维Euler方程的数值模拟结果进一步表明ENO格式具有较高的激波分辨率和较低的数值耗散，在激波附近基本无振荡的特性。     

Preliminary Analysis of Advanced Equilibrium Configuration for the Fusion-Driven Subcritical System

The Fusion-Driven Subcritical System (FDS) is a subcritical nuclear energy system drived by fusion neutron source. In this paper, an advanced plasma configuration for FDS system has been proposed, which aims at high beta, high bootstrap current and good confinement. A fixed-boundary equilibrium code has been used to obtain ideal equilibrium configuration. In order to determine the feasibility of FDS operation, a two-dimensional time-dependent free boundary simulation code has been adopted to simulate time-scale evolution of plasma current profile and boundary position. By analyses, the Reversed Shear mode as the most attractive one has been recommended for the FDS equilibrium configuration design.     

细水雾抑制煤矿巷道火灾的试验和模拟

针对近年来我国煤矿重大外因火灾事故时有发生和灭火设备不足的现状,采用细水雾灭火系统对模拟巷道内柴油火灾进行灭火试验和火灾动力学软件模拟研究.通过对灭火时间和灭火过程中一氧化碳气体的监测发现:细水雾具有快速、安全熄灭煤矿巷道火灾的能力.火灾动力学软件FDS模拟的结果和试验结果的对比表明:FDS能够较好的预测细水雾灭火的动态过程、最高温度、起始降温时间和灭火时间.     

Experimental and numerical study of interactions between sprinklers and natural smoke vents

Real scale experimentations have been conducted in order to investigate interactions that may occur in a compartment where sprinklers and Smoke and Heat Exhaust Vent Systems coexist. Fuel oil spray was used as fire source with steady heat release rate of 400 and 800 kW. Both sprinkler system and natural Smoke and Heat Exhaust Vent Systems were designed according to the French standards. Effect of vent on sprinkler activation time was studied. An analysis of the temperature field inside the compartment was conducted while vent was opened prior or after sprinkler activation. Simulations of the experiments were also carried out with Fire Dynamics Simulator v.6 for validation purpose and also to provide supplementary data regarding soot flow rate and energy extracted at the vent.     

学校宿舍楼火灾烟气流动及温度分布规律研究

建筑物发生火灾时,产生的大量烟气是对人员危害性最大的因素之一。为了研究火灾时的烟气流动规律,运用场模拟软件FDS(Fire Dynamics Simulator)对甘肃地区某内长廊式初级中学宿舍楼在各层门窗及一层主出入口的开启和闭合等不同通风状况下的火灾场景,进行数值模拟,研究了建筑物通风情况对火灾时烟气流动、温度分布的影响规律。分析结果表明:通风面积越大,烟气层高度越高,而走廊和楼梯间温度均较低;烟气容易在楼梯出口处聚集,特别是一层通向外界的出入口封闭后,对流换热效应减弱,烟气很容易蓄积,形成蓄烟池效应。根据研究所得烟气分布规律,提出内长廊式学生宿舍的安全疏散设计和应急管理的改进措施。