A mathematical model of the temperature in a coalfield fire area

The regular pattern of temperature change in a coalfield fire area while the fire is being extinguished was studied. To determine the extinguishing effect, a series of linear, logarithmic, polynomial or exponential mathematical regression models were constructed using the observed temperature data from the Xinjiang coalfield fire extinguishing project. The quadratic polynomial mathematical model had the best fit. A large coal fire oven was also used to simulate the coal fire extinguishing process. The same mathematical regression experiments were carried out on that observed data. The results verified that the quadratic polynomial mathematical model had the best fit. Therefore, a quadratic polynomial mathematical model is proposed to accurately model the temperature-time relationship in a coalfield fire area. An application to coalfield fire suppression shows that the deduced mathe-matical model can be used to predict the temperature conditions and to determine the effect of fire extinguishing, thereby helping to speed up the fire suppression process in the coalfield fire area.

Numerical simulation for recognition of coalfield fire areas by Rayleigh waves

Effective recognition of a coalfield fire area improves fire-fighting efficiency and helps avoid potential geological hazards. Coalfield fire areas are hard to detect accurately using general geophysical methods. This paper describes simulations of shallow, buried coalfield fires based on real geological conditions. Recognizing the coalfield fire by Rayleigh wave is proposed. Four representative geological models are constructed, namely; the non-burning model, the pseudo-burning model, the real-burning model, and the hidden-burning model. Numerical simulation using these models shows many markedly different characteristics between them in terms of Rayleigh wave dispersion and Eigen displacement. These characteristics, as well as the shear wave velocity obtained by inverting the fundamental dispersion, make it possible to distinguish the type of the coalfield fire area and indentify the real and serious coalfield fire area. The results are very helpful for future application of Rayleigh waves for the detection of coalfield fire area.

Determination of fire-access zones along road networks in firesensitive forests

Wild forest fires are one of the greatest environmental disasters affecting forest resources. Along the coastal zone of the Mediterranean region in Turkey, forested areas are classified as first-degree, fire-sensitive areas. Every year, thousands of hectares of forests have been destroyed in Turkey. In this study, fire-access zones were determined in the Mediterranean forests of Turkey, by utilizing geographic information systems （GIS） technology. The effective reach distance of fire hoses from both sides of roads was considered in order to delineate fireaccess zones. The effective reach distance can vary based on the technical capabilities and hydraulic capacity of fire trucks （minimum and maximum pressures on water pump）; terrain structures （uphill, downhill and flat）; and ground slope. These factors and their influences were studied in fire sensitive forest areas located in the eastern Mediterranean city of Kahramanmaras in Turkey. First, terrain structures on both sides of the road network and groundslope classes were determined based on GIS data layers. Then, fire access zones were delineated according to water pressure data, terrain structures, and ground-slope classes. The results indicated that 69.30 % of the forested areas were within the fire-access zones, while the rest of the forest was out of reach the fire hoses. The accessible areas were also calculated for forested areas with different fire- sensitivity degrees. The accessible areas were 69.59, 69.96, and 67.16 % for the forested areas that are sensitive to fires at the first, second, and third degrees, respectively. This finding has implications for the monitoring and management of fire threats in areas outside of the reach distance. The outside areas should receive extra attention and monitoring during the fire season so that fires are detected ahead of time and management has sufficient time to react. Besides, new roads should be considered for these areas in order to access more lands in a shorter amount of time.

Application of the Regulations on Drawing of a Safe Firing Area Map in Weather Modification Operation

Technology for safe firing area maps was introduced firstly,and then potential danger after the launching of shells by an antiaircraft gun and a rocket was analyzed.Finally,problems in the process of applying the regulations and their solutions were discussed.The application of safe firing area maps can provide technical support for the efficient development of weather modification operation.

Factorial analysis on forest canopy density restoration in the burned area of northern Great Xing＇an Mountains, China

The restoration of forest landscape has drawn much attention since thecatastrophic fire took place on the northern slope of Great Xing'an Mountains in 1987. Forest canopydensity, which has close relation to forest productivity, was selected as a key factor to find howmuch the forest quality was changed 13 years after fire, and how fire severity, regeneration way andterrain factors influenced the restoration of forest canopy density, based on forest inventory datain China, and using Kendall Bivariate Correlation Analysis, and Distances Correlation Analysis. Theresults showed that fire severity which was inversely correlated with forest canopy density gradewas an initial factor among all that selected. Regeneration way which did not remarkably affectforest canopy density restoration in short period, may shorten the cycle of forest succession andpromote the forest productivity of conophorium in the future. Among the three terrain factors, theeffect of slope was the strongest, the position on slope was the second and the aspect was the last.

DISCUSSIONS ON FOREST RECOVERY IN THE BURNED AREA IN DAXING'ANLING FOREST REGION

The disastrous fire occurred in northern area of Daxing’anling forest region on May 6, 1987, destroyed a large area of forests. The broad-leaved tree species, such as poplar,birch had regenerated in a great quantity after the fire, but the coniferous species such as larch and scotch pine had difficult to regenerate naturally, This paper put forward that the coniferous forest could be recovered by the planting method of effect strip and effect islet based on the principle of borderline effects and by making full use of the condition of broad-leaved trees.

Structure changes and succession dynamic of the natural secondary forest after severe fire interference

The structure and dynamic succession law of natural secondary forest after severe fire interference in recent 20 years were studied by adopting the method of deducing time series from the spatial sequence of vegetation in Heihe region, Heilongjiang, China.Two typical and widely distributed forest types in the study area, namely forest type A and forest type B, were selected as study subjects.Forest type A is pure broadleaf forest or broadleaf mixed forest mainly composing of superior Betula platyphylla and Populus davidiana in the area with gradient <25°, while forest type B is pure forest or mixed forest composing of superior Quercus mongolica and Betula davurica in the area with gradient >25°.Species richness, vegetation coverage, important value, and similarity index of community in different layers(Herb, shrub, small tree, and arbor layers) were investigated and analyzed for the two typical forests.The results show that after fire interference, the species richness and coverage in each layer in forest type A were higher than that in forest type B.Both for forest type A and B, with elapse of post-fire years, the species richness and coverage of herbs and shrubs showed a decline tendency, while those of arbor layer present a rising tendency.Through comparison of the important values of species in each layer and analysis of community structure changes, the dynamic process of post-fire vegetation succession for forest type A and B was separately determined.Post-fire 80 years' succession tendency of forest type A is B.platyphylla and Larix gmelinii mixed forest.Its shrub layer is mainly composed of Corylus heterophylla and Vaccinium uliginosum, and herb layer is dominated by Carex tristachya, Athyrium multidentatum, and Pyrola incarnate;whereas, the post-fire 80 years' succession of forest type B is Q.mongolica and B.davurica mixed forest.Its shrub layer is mainly composed of lespedeza bicolar and corylus heterophylla and herb layer is dominated by Carex tristachya, Asparagus densiflorus, and Hemerocallis minor.

Wildfires in Botswana and Their Frequency of Occurrence

Fires play an essential part in the maintenance of the environment, but amplified fire activity often leads to adverse effects in the environment such as destruction of property and loss of life. Botswana has experienced wildfires that are caused by humans intentionally and unintentionally. Some of these wildfires grow into mega fires such as the 2008 wildfires. Data of wildfires reported in Botswana from the Department of Forestry and Range Resources and the frequency of occurrence was studied and analyzed. It shows the period of 2006-2017, Ghanzi and Ngamiland districts were mostly affected by wildfires. These districts have protected land such as the wildlife parks which may lead to the outbreak of natural wildfires that burns unnoticed due to minimal movements of people. The wildfires reported in each district show an increase over the years and this may affect the smooth running of operations.

自燃煤矸石山火区表面温度场三维重构与实践

【目的】煤矸石山自燃灾害严重破坏生态环境,影响安全生产,已成为我国生态文明建设进程中的瓶颈问题,为科学制定灭火方法及实施灭火工程,自燃煤矸石山火区范围的准确探测至关重要。【方法】提出采用无人机热红外倾斜摄影测量技术探测高温区三维分布的思路,研发热红外图像多尺度高斯滤波细节增强技术,突出目标边缘信息;基于FLIR Tools软件开发工具包SDK (software development kit)开发热红外图像一键式批量化处理软件,利用ThreadPool高效地开展热红外图像的多线程异步处理,全局统一所有热红外图像颜色阈值与温度数值的对应关系;最后采用批量处理后的热红外图像进行自燃煤矸石山火区表面温度场三维重构,并在陕西某煤矸石山火区进行了现场应用。【结果和结论】结果表明:(1)经过多尺度高斯滤波细节增强后,热红外彩色图像细节特征得到显著增强,热红外图像信息熵由6.989提高到了7.624。(2)所开发的热红外图像批量化处理软件可在10 min内对1 000张热红外图像进行快速处理,极大提高了工作效率。(3)上述技术在陕西某煤矸石山火区现场成功构建了一区及二区煤矸石山火区三维表面温度场,分别圈定了11 693 m^(2)和10 800 m^(2)高温区,为火区发展态势评估和后续灭火方案设计提供了支撑。研究成果可应用于煤矸石山火灾、煤田火灾、垃圾填埋场火灾、森林火灾以及建筑火灾等高温场景的温度场三维重构,为火区侦查、火情调查及火源位置诊断提供详实的火场数据支持。

基于图像内凹度的矿井外因火灾识别及抗干扰方法

尽早发现矿井火灾并处置,可避免或减少人员伤亡和财产损失及次生事故的发生。井下没有日光、月光、星光及闪电等自然光源,影响矿井火灾图像识别的主要是矿井光源。圆形度能够排除圆形光源的干扰,但难以排除非圆形光源的干扰。矩形度能够排除矩形光源的干扰,但难以排除非矩形光源的干扰。在工程实际中,因摄像机的拍摄角度不同,矿井光源图像会出现变形,无法呈现理想的规则形状,使用圆形度和矩形度算法难以排除矿井光源的干扰。揭示了火焰图像轮廓外接图面积明显大于其图像实际面积,圆形灯、长方形灯和正方形灯等矿井实际光源图像轮廓外接图面积近似等于其光源图像实际面积等特点。提出基于图像内凹度的矿井火灾识别及抗干扰方法,计算目标图像面积与图像轮廓外接图面积的比值(即图像内凹度),根据火焰图像内凹度数值较小,而矿井光源图像内凹度数值较大,区分火焰与矿井光源。提出的内凹度方法不受摄像机距检测目标距离和图像大小、摄像机安装位置和摄像机拍摄检测目标的角度、矿井光源形状等影响,适应性强,识别准确率高。实验表明,内凹度识别方法计算得到的矿井干扰光源减去火焰图像平均差值最大,波动最小,区分度最好,受摄像机拍摄角度及距离影响最小,抗干扰能力最强,准确率为91.6%。矩形度识别方法计算得到的矿井干扰光源减去火焰图像平均差值较大,波动较小,区分度较好,受摄像机拍摄角度及距离影响较小,抗干扰能力一般,准确率为72.5%。圆形度识别方法计算得到的矿井干扰光源减去火焰图像平均差值最小,波动最大,区分度最差,受摄像机拍摄距离影响较小,受摄像机拍摄角度影响大,抗干扰能力最差,准确率为12.0%。因此,提出的内凹度识别方法,优于矩形度和圆形度,区分度最好,受摄像机拍摄角度及距离影响最小,抗干扰能力最强。

Effects of recovery time after fire and fire severity on stand structure and soil of larch forest in the Kanas National Nature Reserve, Northwest China

Forest recovery may be influenced by several factors, of which fire is the most critical.However, moderate-and long-term effects of fire on forest recovery are less researched in Northwest China.Thus, the effects of different forest recovery time after fire(1917(served as the control), 1974, 1983 and 1995) and fire severities(low, moderate and high) on larch(Larix sibirica Ledeb.) forest were investigated in the Kanas National Nature Reserve(KNNR), Northwest China in 2017.This paper analyzed post-fire changes in stand density, total basal area(TBA), litter mass, soil organic carbon(SOC) and soil nutrients(total nitrogen, total phosphorus and total potassium) with one-way analyses of variance.Results indicate that litter mass, TBA, SOC and soil nutrients increased with increasing recovery time after fire and decreasing fire severity, while the stand density showed an opposite response.The effects of fire disturbance on SOC and soil nutrients decreased with increasing soil depth.Moreover, we found that the time of more than 43 a is needed to recover the litter mass, TBA, SOC and soil nutrients to the pre-fire level.In conclusion, high-severity fire caused the greatest variations in stand structure and soil of larch forest, and low-severity fire was more advantageous for post-fire forest stand structure and soil recovery in the KNNR.Therefore, low-severity fire can be an efficient management mean through reducing the accumulation of forest floor fuel of post-fire forests in the KNNR, Northwest China.

森林环境文物建筑集中区域灭火救援能力评估

针对森林环境文物建筑集中区域环境复杂,难以准确评估区域灭火救援能力等问题,基于层次分析法(AHP),提出耦合森林因素的单体文物建筑灭火救援能力评估方法,涵盖建筑材料、森林防火隔离带、消防水源等19个二级指标;在单体评估基础上,从区域视角建立一种基于变权法的森林环境文物建筑集中区域灭火救援能力评估模型;并引入惩罚占主导的混合型变权函数,设置评价策略,确定惩罚与激励区间,区分文物建筑保护等级,提出风险等级划分方法;通过实地调研和数据收集,结合定权法和变权法评价森林环境文物建筑集中区域(岳麓山风景名胜区)的灭火救援能力。结果表明:单体文物建筑评级为优、良、中、次、差的数量占比分别为12%、20%、32%、20%、16%。区域定权法得分为75.27(Ⅲ级,不需采取提升措施),变权法得分为69.97(Ⅳ级,需采取提升措施);建议采取增设电气火灾预警系统、增加森林防火隔离带等措施来提升灭火救援能力。

元谋干热河谷区红火蚁药剂防控研究

红火蚁是元谋干热河谷区一种具有重大危害的危险性入侵生物,为了筛选出适用于干热河谷区的红火蚁防治药剂,开展了7种杀虫剂对红火蚁的防效试验。结果表明:对蚁巢的防控效果,药后7 d以8%高效氯氰菊酯可湿性粉剂的最好,其次是0.73%氟蚁腙饵剂,平均防效分别为100.00%和93.75%,药后14和21 d时,8%高效氯氰菊酯可湿性粉剂和2.05%氟蚁腙吡虫啉杀虫饵剂的防效均达100.00%,其他药剂处理的防效均为93.75%;8%高效氯氰菊酯可湿性粉剂在施药后1 d时单个蚁巢工蚁的虫口减退率达100.00%,且显著高于除0.1%呋虫胺饵剂处理以外的其他处理,施药后7 d供试药剂的虫口减退率均在90%以上,但在施药后21 d时其虫口减退率均出现下降。因此,可交替使用7种供试药剂进行红火蚁的防控,建议先撒施0.2%高效氯氰菊酯粉剂、0.73%氟蚁腙饵剂、2.05%氟蚁腙吡虫啉杀虫饵剂等控制红火蚁,然后用8%高效氯氰菊酯可湿性粉剂灌巢彻底铲除红火蚁。

安全疏散视角下的地下商业空间垂直疏散体等候区设计参数研究

阐述垂直疏散体的定义,通过分析地下商业空间的空间类型、平面布局与流线得到典型平面,探究垂直疏散体等候区面积与疏散效率的关系以及取值范围,为工程实践与地下空间疏散理论研究提供数据支撑。

重庆市2022年8月森林火灾火烧区特点及火后泥石流易发性评价

2022年8月重庆市江津区、巴南区、北碚区相继爆发森林火灾,总过火面积约35 km^(2)。火灾后火烧迹地植被及土壤结构遭到破坏,坡表堆积了厚度1~5 cm不等的灰烬层,受强降雨影响一旦爆发火后泥石流,将对附近村镇基础设施及群众生命财产构成严重威胁。通过遥感解译、现场调查及试验,查明了本次森林火灾火烧区空间分布特征,实测了火烧迹地灰烬层厚度、土壤饱和导水率等参数。结果表明研究区重度、中度和轻度火烧区分别占9.6%、34.0%和56.4%,其对应的坡面灰烬-结构扰动层平均厚度分别为5.10,3.28,1.15 cm。基于专家经验预测模型对火烧区共95条潜在泥石流沟道进行火后泥石流易发性评价,其中1条为高等易发,43条为中等易发,44条为低等易发,7条为不易发,分别占总数的1.05%、45.26%、46.32%、7.37%。考虑到现状条件下各泥石流沟域内中度和重度火烧区仍残留有大量灰烬、泥沙等松散固体物源,且土壤表现出较强的斥水性,中等及高等易发性沟道在雨季一旦受集中降雨影响,爆发火后泥石流的可能性较大。研究成果可为火烧迹地火后泥石流灾害预防与风险管理提供科学依据。

基于地面瞬变电磁和无人机红外感知煤矿隐蔽致灾因素探测

煤矿开采受隐蔽致灾因素影响易诱发矿山五大灾害,因此,需要对煤矿隐蔽致灾因素进行全面探测。为提高探测效率,本次研究在分析隐蔽致灾因素的基础上,对未来开采区域实物工作量进行布置,重点采用地面瞬变电磁和无人机载红外探头探测等高效率技术和补充测试方法对采空区和隐伏火区进行探测。探测结果表明:未来开采区域地面瞬变电磁查明了13处低阻异常,共计19.93万m^(2)。井田范围温度介于-24~8℃之间,其中,高温区域主要分布于测区西部区域和西北和西南周边区域,结合实地考察未发现潜在火区。本次研究为相关矿山隐蔽致灾因素探测提供了参考。

内蒙古大兴安岭林火时空动态的变化特征

内蒙古大兴安岭森林火灾频发,研究其季节性变化趋势及空间动态分布特征,对今后该地区森林防火期划分和防火资源的合理分配具有重要意义。利用Mann-Kendall趋势检验法、滑动t检验法对1981—2018年内蒙古大兴安岭森林火灾数据进行趋势和突变分析,使用分位数回归法研究影响森林火灾过火面积的时间与空间因素,得出内蒙古大兴安岭森林火灾在时间和空间上的动态变化特征。结果表明:内蒙古大兴安岭森林火灾整体呈先下降(1981—1999年)再上升(2000—2007年)又下降(2008—2018年)的趋势。森林火灾主要发生在春、夏、秋三季,春季森林火灾变化较复杂,波动明显,在1991年发生突变;秋季森林火灾波动较平缓,但在1994年发生突变;2004—2011年期间夏季森林火灾明显增长,火险期向夏季发生偏移和延长;冬季发生火灾较少。森林火灾过火面积与火灾持续时间呈正相关,尤其在高分位点处,正相关性更加显著。内蒙古大兴安岭森林火灾主要发生在鄂伦春自治旗等地,从空间横向动态变化来看,整体呈现由西南向东北递增的趋势;从空间纵向动态变化来看,海拔对森林火灾过火面积的影响并不显著。建议应加强内蒙古大兴安岭东北地区及春、夏两季的林火监测和防火宣传,适当调整森林防火期和防火资源时空分配,将有助于减少内蒙古大兴安岭森林火灾的发生。

辉南县国有林区森林火灾隐患源头治理措施

本文从明确工作指导思想、目标、方式方法和保障措施几个方面总结了辉南县在开展国有林区森林火灾隐患源头治理工作中采取的措施,将森林火灾隐患源头治理工作作为加强国有林区森林防灭火工作的有效手段,使国有林区森林火灾隐患得到有效遏制,收到了明显成效。

煤矿火灾智能预警系统研发与应用

目前煤矿火灾监测系统实现了对矿井煤自燃标志性气体、温度、烟雾、火焰等部分指标的单独监测,未对煤矿火灾相关因素进行有效、全面、统一的监测。针对该问题,从内因、外因2个方面分析了煤矿火灾潜在危险因素,提出一种分源分区监测火情态势的方法。内因火灾方面,主要针对较易发生火灾的工作面采空区、密闭采空区及人工自然发火观测点等进行监测;外因火灾方面,主要针对机电硐室及其配电点、带式输送机系统、电缆等方面进行监测。建立了煤矿火灾分源分区监测指标体系,采用人工监测或在线监测的方式定期采集或更新火灾特征参量数据,按数据采集方式及影响程度,将火灾监测指标分为动态指标、静态指标和关联指标。设计了火灾智能预警系统的总体架构和业务流程,采用基于多指标联合逻辑推理的预警方法实现内因火灾预警,采用基于D-S证据理论的多参量融合预警方法实现外因火灾预警。现场试验结果表明,火灾智能预警系统实现了对矿井火灾的有效监测预警,具有煤矿火灾风险预警“一张图”可视化展示功能,同时具备火灾智能模拟演示功能及避灾路线动态规划功能。

城市火灾风险因素分析及防控对策——以郑州市为例

城市是区域的社会、经济和文化中心。如果发生严重火灾事故,引起的损失难以估量。以郑州市为例,以2020—2022年发生的火灾事故统计数据为基础,分析城市火灾的总体特点、火灾风险因素及问题短板,提出五维度城市火灾风险应对策略,为降低城市火灾发生率、增强城市应对火灾风险的能力提供经验借鉴和理论支撑。