基于MODIS热红外辐射的归一化差异火点指数NDTI研究

本研究使用MODIS红外辐射遥感数据在分析了异常热点光谱辐射特性的基础上,提出一个新的火情监测模型NDTI火点指数,并通过几起较大森林火灾对该模型进行了分析和验证,给出了该监测模型的详细算法.这种双通道比值指数和NDVI一样具有衰减仪器噪声和抵消常规大气影响的优点.研究表明,4 μm火点辐射通道和11 μm背景分量通道的组合突出了火点信息,选择合适的NDTI门限,NDTI指数能够准确检测火点,识别率可达到93%.根据对实时接收轨道的有限实测,由于使用极少的数据集数学运算操作,NDTI模型比MODIS推荐火情算法在计算速度上快两倍以上.EOS MODIS探测器具有多光谱和高光谱以及对热点监测动态范围宽的特点,MODIS的下一代多光谱探测器NPOESS NPP VIIRS同样继承了MODIS的优势,为NDTI算法模型提供了广阔的应用前景.     

A comparison between superfine magnesium hydroxide powders and commercial dry powders on fire suppression effectiveness

The effectiveness of superfine magnesium hydroxide powders and commercial dry powder in fire suppression were compared in a laboratory-scale, immovable fire suppression apparatus. The investigation focused on their suppression effectiveness under various pressures. It likewise studied the relationship between the powders’ surface structures and their effectiveness on fire suppression. The microcosmic structure of the powders was observed by scanning electron microscope (SEM), while the Thermal Gravity Analysis (TGA) technique was used to analyze the thermal behavior of the superfine magnesium hydroxide powders. By analyzing the results, it could be concluded that the pressure, the particle size, and the microcosmic structure of the powders’ surface mainly decide the capability of the powders to extinguish the fire. Comparing this with commercial dry powders, superfine magnesium hydroxide powders extinguished the fire in less than 10 s.     

林火蔓延预测计算机图形显示系统

通过借鉴Rothermel(1972年)建立的林火蔓延的数学模型。提出了适合我国林区可燃物分布特性的火蔓延数学模型,并在其基础上筑构出用于估算特定可燃物分布状况、变环境条件下火蔓延趋势的专家系统—FF—1G软件。该软件能迅速、直观地显示出复杂地形条件下,相应的环境风速作用时地表火火蔓延不同阶段的过火区域分布状况。对若干实例计算的结果表明,其可靠性高,实用性强,应用背景广。     

Fire risk management system for safe operation of large atmospheric storage tanks

This paper has been prepared by its authors to show the benefits coming from the application of the fire risk assessment methodology prepared by the “LastFire^© Project” group of experts. Now a days this methodology seems to be very effective to face the fire risk connected with large atmospheric storage tanks. It has been developed during the period 1997–2005 the HSE & operations experts from experts 16 worldwide operating oil companies. The authors, by “ad hoc” created software package, show the benefit coming from the applications of the LastFire^© methodology and how, from this, using the methodology and the supporting tad, realize a coherent fire strategy in the form of a Fire Risk Management System. Same workflow could also be extended to the issues connected with other problems related with large atmospheric tanks storing hydrocarbons, such as environmental impact by soil pollution, to create a common frame walk of assessment not can be shared with authorities as well. The proposed methodology, moving from the original project, sets as an effective “Fire Hazard Management Approach” in line with the most recent trends (even enforced by the regulations) shared at international levels, that propose the integration of risk assessment with prevention and protection measures selection based on achieved risk reduction, costs, time needed, etc.     

火灾现象的数值模拟及其应用

本文讨论了模拟火灾现象的数值方法及其应用。着重研究了火焰发热、空气流动和烟尘传播的数学模型，讨论了紊流模型中浮力项的处理和边界条件的简化，并介绍了这一课题的研究现状和发展方向。     

钢筋混凝土矩形梁的当量耐火时间

为了正确评估钢筋混凝土矩形梁在实际火灾条件下的承载力,以一般室内火灾轰燃后的房间平均温度一时间曲线为火作用,以热传导和建筑结构耐火理论为基础,以梁在实际和标准火灾下的承载力相等为等效准则,用数值计算方法研究梁的当量耐火时间,并用最小二乘法导出其计算公式.火灾房间火灾荷载越大,开口因子越小,梁的当量耐火时间越长;反之越短.所给梁的当量耐火时间可用于建筑结构性能化耐火设计与评估:当火灾荷载密度较大,开口因子较小时加大梁的截面参数以获得安全性,反之,减小截面参数以获得经济性.     

Just Blowing Smoke? Residents’ Social Construction of Communication about Wildfire

This study uses social constructionism as a basis for understanding the effectiveness of communication about wildfire risk between agency officials and wildland–urban interface (WUI) residents. Risk communication literature demonstrates a well-documented difference in the way land managers and stakeholders conceptualize risk. This is especially true of fire because management of these hazards have changed so drastically in past decades; fire managers have typically struggled to clearly articulate the current management policy to the public or integrate their specific knowledge in the risk management process. This study contributes to an understanding of how WUI residents construct communication about wildland fire and agency effectiveness in communicating the new era of fire inclusion. Specifically, we explore the personal and professional sources of information residents’ use to understand their fire risk and the subjects they would like more information about. We also explore the continued viability of Smokey Bear, the most enduring symbol of fire management.     

The fire frequency analysis branch of the pyrostatistics tree: sampling decisions and censoring in fire interval data

Statistical characterization of past fire regimes is important for both the ecology and management of fire-prone ecosystems. Survival analysis—or fire frequency analysis as it is often called in the fire literature—has increasingly been used over the last few decades to examine fire interval distributions. These distributions can be generated from a variety of sources (e.g., tree rings and stand age patterns), and analysis typically involves fitting the Weibull model. Given the widespread use of fire frequency analysis and the increasing availability of mapped fire history data, our goal has been to review and to examine some of the issues faced in applying these methods in a spatially explicit context. In particular, through a case study on the massive Cedar Fire in 2003 in southern California, we examine sensitivities of parameter estimates to the spatial resolution of sampling, point- and area-based methods for assigning sample values, current age surfaces versus historical intervals in generating distributions, and the inclusion of censored (i.e., incomplete) observations. Weibull parameter estimates were found to be roughly consistent with previous fire frequency analyses for shrublands (i.e., median age at burning of ~30–50 years and relatively low age dependency). Results indicate, however, that the inclusion or omission of censored observations can have a substantial effect on parameter estimates, far more than other decisions about specifics of sampling.

A land management history for central Queensland,Australia as determined from land-holder questionnaire and aerial photography

Features of the land management history over a 125,755 km(2) area of central Queensland, Australia were determined from a variety of sources. A random sample of 205 site locations provided the basis for determining trends in land use. Trends in vegetation clearing were determined using sequential aerial photography for the sample sites, revealing a steady rate averaging nearly 1% of the region per annum over 41 years. This measure of sustained clearing over a large region is higher than recently published clearing rates from South America. Land types have been selectively cleared with over 90% of the Acacia on clay land type having been cleared. A land-holder questionnaire pertaining to the random sites yielded a response rate of 71% and provided information on vegetation clearing, ploughing, tree killing (ring-barking or tree poisoning), and fire frequency, season and intensity. The land-holder responses were compared with independent data sources where possible and revealed no mis-information. However, land-holders may have been marginally less likely to respond if the sample area had been cleared, although this effect was not statistically significant. Ploughing and tree killing are variable depending on land type, but the former has affected about 40% of the Acacia on clay land type, effectively eliminating options for natural regrowth. The proportion of decade-site combinations that were reported as having no fires increased from 22% in the 1950s to an average of 42% for subsequent decades, although the reporting of more than one fire per decade has been relatively constant through the study period. The reporting of at least one fire per decade varies from 46% for the Acacia on sand land type to 77% for the Eucalypt on sand land type for decade-site combinations. Fires are more intense when associated with clearing than in uncleared vegetation, but the proportion of cool and hot fires is relatively constant between land types in uncleared vegetation. Nearly all fires reported were either in spring or summer and this seasonally restricted regime is probably at variance with Aboriginal fire regimes. This study describes the rapid transformation of central Queensland. This has yielded substantially increased agricultural production but may also result in a range of negative impacts and these are discussed.     

基于隧道火灾的消防机器人系统研究

首先介绍了隧道消防的重要意义 ,分析了隧道火灾的特点 ,提出一种早发现、早灭火的隧道消防系统方案。针对隧道消防机器人的功能要求 ,提出了机器人总体设计方案 ,确定了一种安装空间小、工作范围大的机器人执行机构。同时将一种集测温、测烟雾粒子、测气压等多种功能于一体的新型传感器应用于隧道火灾的预报中 ,提高了隧道火灾的报警有效率。这种隧道消防机器人系统的研制为隧道火灾的早期扑救提供了一种新的途径 ,对隧道、库房、地下停车场以及其他建筑内消防具有广泛的应用前景。