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151.
An ecological data base for the San Jacinto Mountains, California, USA, was used to construct a probability model of wildland
fire occurrence. The model incorporates both environmental and human factors, including vegetation, temperature, precipitation,
human structures, and transportation. Spatial autocorrelation was examined for both fire activity and vegetation to determine
the specification of neighborhood effects in the model. Parameters were estimated using stepwise logistic regressions. Among
the explanatory variables, the variable that represents the neighborhood effects of spatial processes is shown to be of great
importance in the distribution of wildland fires. An important implication of this result is that the management of wildland
fires must take into consideration neighborhood effects in addition to environmental and human factors. The distribution of
fire occurrence probability is more accurately mapped when the model incorporates the spatial term of neighborhood effects.
The map of fire occurrence probability is useful for designing large-scale management strategies of wildfire prevention. 相似文献
152.
153.
火灾烟气伤害机理和伤害模型 总被引:2,自引:0,他引:2
建筑物发生火灾时,燃烧产生的烟气对人构成主要威胁。本文分析火灾烟气的伤害机理,提出烟气伤害指数概念及其计算方法,探讨它在材料防火性能评价和建筑物火灾安全评价方面的应用可能性。 相似文献
154.
Abstract: The acceleration of processes such as forest fragmentation and forest fires in landscapes under intense human pressures makes it imperative to quantify and understand the effects of these processes on the conservation of biodiversity in these landscapes. We combined information from remote-sensing imagery and ground maps of all fires in the Mudumalai Wildlife Sanctuary (MWLS) in the Western Ghats of India over 14 years (1989–2002). These spatial data on fire occurrence were integrated with maps of vegetation types found in the MWLS to examine fire conditions in each. We calculated the average fire-return interval for each of the vegetation types individually and for the MWLS as a whole. Using vegetation data from the larger Nilgiri Biosphere Reserve and the entire Western Ghats region, we conservatively estimated fire-frequency information for these larger regions. Because the MWLS does not contain tropical evergreen or montane forests, we were unable to estimate fire conditions in these forest types, which represent 31% of all Western Ghats vegetation cover. For the MWLS, all vegetation types had average fire-return intervals of <7 years, and the sanctuary as a whole had a fire-return interval of 3.3 years. Compared with a 13-year MWLS fire data set from 1909–1921, this represents a threefold increase in fire frequency over the last 80 years. We estimated average fire-return intervals of roughly 5 years for both the larger Nilgiri Biosphere Reserve and the entire Western Ghats region. Given other recent reports, the estimated fire frequencies for the Western Ghats forests outside protected reserves are conservative. We conclude that the current fire regime of the Western Ghats poses a severe and persistent conservation threat to forests both within and outside protected reserves. 相似文献
155.
When two or more pool fires happen to burn so close to each other that they interact, they are termed ‘multiple pool fires’ (MPF). Past accident analysis reveals that MPFs occur quite frequently in chemical process industries. Controlled experiments done so far to study MPFs have indicated that MPFs lead to increase in the fuel burning rate, flame height and heat release rate (HRR) but the nature and the extent of the impacts of different factors on these manifestations is as yet poorly understood. In this context computational fluid dynamics (CFD) appears to be a tool which can enable more detailed and realistic simulation of MPFs than other possible approaches, especially due to its ability to closely approximate the underlying physical phenomena. In tank farms there are situations where different storage tanks are placed at different elevations yet close to each other. If such tanks happen to catch fire, the resulting fires may influence each other in a manner that may be a function of the difference in the tanks’ elevation. However no CFD study has been carried out which addresses this type of situation. Hence an attempt has been made to employ CFD to study MPFs involving two pools with fuel surfaces are at different elevations. Results reveal that good correlation is possible between the experimental findings and the CFD simulations. 相似文献
156.
L. Tacconi P. F. Moore D. Kaimowitz 《Mitigation and Adaptation Strategies for Global Change》2007,12(1):55-66
Fires have attracted interest and generated alarm since the early 1980s. This concern has been particularly evident in tropical
forests of Southeast Asia and the Amazon, but disastrous fires in recent summers in Australia, Europe, and the United States
have drawn worldwide attention.
Concern about forest fires, and related air pollution and biodiversity impacts, led international organisations and northern
countries – such as the Asian Development Bank, the European Union, the Food and Agriculture Organisation, the United Nations
Environment Programme, the World Bank, and the government of Germany – to undertake fire assessments and provide technical
assistance. Nongovernmental organisations, such as the International Union for Conservation of Nature and Natural Resources
and World Wide Fund for Nature, have also devoted increased attention to fires. Aiming at prevention of future fires, 40 fire
projects and missions costing well over US$30 million have worked in Indonesia over the last 20 years. Despite the money and
effort spent on them, fires continue to burn every year. It may appear to some that efforts to address the ‘fire problem’
have not been effective as fires still occur.
There remains a lack of clarity about ‘fire problems’, which has, at times, led to the adoption of policies that may have
negative impacts on livelihoods, the environment, and the economy. Two ‘simple’ changes in the way fires are considered would
significantly improve fire-related policies and initiatives.
These two points are discussed in the context of Southeast Asia, and particularly Indonesia, as an example of the problems
and questions faced by tropical countries. We argue that efforts on fires so far have generated increased knowledge of the
’fire problem’; now, we need to capitalize on that knowledge to avoid wasting money in the future. 相似文献
• | Fires should be seen as a component of land management processes, rather than as a ‘problem’ to be prevented, suppressed, or mitigated. |
• | Not all fires are the same. |
157.
森林火灾灾情快速预判模型 总被引:1,自引:1,他引:0
为在火灾发生时进行灾情的快速评估,为消防决策提供参考,提出一种简化的林火蔓延模型。通过遥感影像,获取火灾首日燃火点和火场边界,利用风向、风速和USDA蔓延模型数据库中对应植被类型的蔓延速度,进行林火蔓延计算,预判无干扰状态下的林火蔓延范围,以达到灾情快速预判的目的。通过2006年黑龙江省和2009年中蒙边境特大森林草原火灾案例的分析,结合运用卫星遥感图像对逐天火迹和火点解译的结果,验证该模型的可靠性及适用性。研究结果表明,基于实时遥感影像与气象预报信息,运用简化的林火蔓延模型,并结合林火宏观扩散的特征,能够对火灾灾情的发展进行快速研判。 相似文献
158.
LNG池火热辐射模型及安全距离影响因素研究 总被引:1,自引:1,他引:0
重点对LNG池火热辐射模型,模型应用方式,以及热辐射安全距离的影响因素做了详细研究,给出池火热辐射模型采用及安全距离计算的方法。对常用的热辐射计算模型(点源模型、LNGFire3和PoFM ISE模型)加以介绍,并对3种模型做了对比研究。PoFM ISE模型充分考虑大池火直径时不完全燃烧的因素以及风速对火焰高度的影响,建议当风速大于1.5 m/s,池火直径大于20 m时采用。同时,进一步研究影响LNG池火热辐射安全距离的各种因素,包括池火直径、风速、环境温度和湿度,从而得出不同条件下池火热辐射安全距离的要求。 相似文献
159.
160.
Release of PCDD and PCDF from biomass combustion such as forest and agricultural crop fires has been nominated as an important source for these chemicals despite minimal characterisation. Available emission factors that have been experimentally determined in laboratory and field experiments vary by several orders of magnitude from <0.5 μg TEQ (t fuel consumed)−1 to >100 μg TEQ (t fuel consumed)−1. The aim of this study was to evaluate the effect of experimental methods on the emission factor.A portable field sampler was used to measure PCDD/PCDF emissions from forest fires and the same fuel when burnt over a brick hearth to eliminate potential soil effects. A laboratory burn facility was used to sample emissions from the same fuels. There was very good agreement in emission factors to air (EFAir) for forest fuel (Duke Forest, NC) of 0.52 (range: 0.40-0.79), 0.59 (range: 0.18-1.2) and 0.75 (range: 0.27-1.2) μg TEQWHO2005 (t fuel consumed)−1 for the in-field, over a brick hearth, and burn facility experiments, respectively. Similarly, experiments with sugarcane showed very good agreement with EFAir of 1.1 (range: 0.40-2.2), 1.5 (range: 0.84-2.2) and 1.7 (range: 0.34-4.4) μg TEQ (t fuel consumed)−1 for in-field, over a brick hearth, open field and burn facility experiments respectively. Field sampling and laboratory simulations were in good agreement, and no significant changes in emissions of PCDD/PCDF could be attributed to fuel storage and transport to laboratory test facilities. 相似文献