OPTIMAL INVESTMENT IN THE PROTECTION OF A VULNERABLE BIOLOGICAL RESOURCE

It is assumed that the probability of destruction of a biological asset by natural hazards can be reduced through investment in protection. Specifically a model, in which the hazard rate depends on both the age of the asset and the accumulated invested protection capital, is assumed. The protection capital depreciates through time and its effectiveness in reducing the hazard rate is subject to diminishing returns. It is shown how the investment schedule to maximize the expected net present value of the asset can be determined using the methods of deterministic optimal control, with the survival probability regarded as a state variable. The optimal investment pattern involves “bang-bang-singular” control. A numerical scheme for determining jointly the optimal investment policy and the optimal harvest (or replacement) age is outlined and a numerical example involving forest fire protection is given.     

基于突变论的林火蔓延分析

在对森林火灾进行能量和质量守恒分析的基础上,把尖点突变模型应用于森林火灾蔓延的预测,使突变理论在 森林火灾的模型中从理论上有了初步的应用。文中计算了林火发生突变时的一些分歧点,分析了林火突变的特点和变化规 律。     

火力发电厂废水中悬浮物处理的影响因素探讨

对火力发电厂废水中悬浮物处理的影响因素如pH值、水温、接触介质、进水水质、混凝剂加入量等进行分析，对主要影响因素水温和混凝剂加入量进行了试验分析，制定出废水悬浮物处理的合理方案。     

早期火灾图像监测技术的应用与比较

本文对可提供图像信息的火灾物理现象进行了具体分析，讨论了利用摄像技术进行早期火灾探测的可能性、使用条件以及图像监测技术在火灾探测中的地位和作用，进行了若干种图像监测技术的对比实验，得出了相应的结论。     

Flammability studies of 3-methyl pyridine/water system

In industrial processes, information on the safety property of chemicals is essentially crucial for safe handling during unit operations. Ensuring the safe use of combustible or flammable substances in processes is unlikely without detailed investigations of their flammability characteristics and related hazards. We studied 3-methyl pyridine (3-picoline), e.g., flammability limits (LFL/UFL), maximum explosion pressure (P _max), maximum explosion pressure rise (dP/dt)_max, minimum oxygen concentration (MOC), vapor deflagration index (K _g), and characterized the influence of inert steam (H₂O) on critical parameters for 3-picoline/water mixtures at 270°C, 1 atm, various oxygen concentrations, and vapor mixing ratios (100/0, 30/70, 10/90 and 5/95 vol.%) with a 20-L-Apparatus in simulated conditions, respectively. The results showed that the flammability characteristics of 3-picoline_(aq) all increased with the oxygen concentration. However, as the composition of inert steam increased, the flammability parameters and the degree of fire and explosion hazards were significantly reduced, instead. This study elucidated the flammability properties of 3-picoline mixed with inert steam. The conclusions could be applied to proactively prevent the relevant processes from incurring fire and explosion accidents.     

Fire retardant synergism between melamine and triphenyl phosphate in poly(butylene terephthalate)

The fire retardant efficiency of melamine (MA) and triphenyl phosphate (TPP) in poly(butylene terephthalate) (PBT) was studied by the limiting oxygen index (LOI) and the UL94 test. On adding 10 wt. % MA and 20 wt. % TPP, LOI increased from 20.9 to 26.6 and the UL94 V-0 rating was achieved. SEM and DSC analyses show that the fire retardants are compatible with PBT and facilitate crystallization of PBT. The occurrence of an interaction between MA + TPP and PBT was elucidated by TGA, dynamic FTIR, and pyrolysis/GC/MS. MA + TPP changes the degradation path of PBT and modifies the compositions of the gas and condensed-phase products.     

林火中的阴燃现象:研究前沿与展望

森林中的植物腐殖质和有机泥炭土的阴燃是地球上尺度最大的燃烧与火灾现象,造成了巨大的经济损失及跨国界的雾霾,并严重破坏了生态系统.本文综述了阴燃林火的基础燃烧理论和化学反应机理,总结了其点火、火蔓延和熄火的行为特性.同时,归纳了近年来泥炭阴燃火的研究动态,包括如何通过小尺度的阴燃实验理解大尺度的阴燃林火,如何构建阴燃的数...     

稠油油藏高温盐析调剖的孔渗表征方法研究

深层高温油藏在开采过程中,由于近井地带压力变化剧烈,地层水蒸发致使结晶盐析出,进而导致储层孔隙度、渗透率降低.为研究稠油油藏高温盐析调剖的孔渗变化规律,根据盐类溶解/沉淀原理及储层孔隙度渗透率关系和填砂管模型高温盐析实验结果,建立了考虑地层水蒸发、水中氯化钠析出和储层孔渗变化的综合盐析模型.研究结果表明:随着堵剂注入量...     

斜面上任意抛射的最佳抛射角

对斜面上任意抛射的最佳抛射角和射程计算公式进行了推导.     

故障树模块化在装甲车辆灭火系统故障诊断中的应用

为了实现装甲装备灭火系统故障的快速诊断,提出了一种故障树模块化分析方法;对灭火系统故障树进行深度优先最左遍历,并记录遍历过程,按照遍历顺序对故障树中的每个事件进行标定,并将灭火系统故障树划分为相互独立的模块,依据划分的模块可以通过故障现象对模块内的故障进行排查及修复;实验结果分析表明,该方法可以快速修复模块故障,恢复系统功能,简化了以往对灭火系统所有子事件遍历查错的繁琐过程。该方法同样可以计算故障模块的失效概率,并可以实现故障模块的整体更换,恢复系统性能;证明了故障树模块化方法在灭火系统故障诊断中具有较高的效率,简化了灭火系统诊断流程,在装甲车辆其他系统故障诊断中具有借鉴作用,符合现代作战对于装备保障的需求。