Topical scientific and practical issues of wildland fire problem

Problem of wildfires has not been resolved anywhere in the world. Mere increase of technical power does not lead to desirable results. Forests of developed countries burn as actively as those in Africa or in Russia. The main reasons of wildfire problem are as follows: (1) Constant wandering of dry seasons over the planet causing outbreaks of wildfires. (2) Unpredicted self-development of ordinary wildfires into awful fire disasters. (3) Difficulties in delivery and use of heavy machines on hardly accessible territories. (4) Absence of a perfect technique for economic evaluation of how effectively the wildfire control system works. (5) Absence of the system of payments encouraging wildfire fighters. To solve the problem of wildfires in Russia it is necessary to: (1) Create the Russian wildfire behaviour and fire effects prediction system on the basis of the developed classification of vegetation fuels and methods of their mapping as well as maximum utilization of forest inventory information and Geographic Information System (GIS). (2) Elaborate a technique of proper wildfire monitoring including estimation of vegetation damage. (3) Improve daily rating of regional fire danger. (4) Improve fire-preventive arrangement of the territory covered by vegetation, the main goal being creation of favourable conditions for active fire management. (5) Choose the main direction in elaboration of fire-fighting means and methods taking into account their universality, simplicity, reliability, etc. (6) Elaborate an improved technique for estimation of economic effectiveness of the wildfire control system. (7) Develop international cooperation of scientists and professionals in fire management.     

绿色学校垃圾分类回收体系的建设及运行

创建绿色学校是学校参与循环经济建设的具体表现,中国目前建成的绿色学校基本进行了垃圾分类回收,但其垃圾分类缺乏针对性和科学性。在分析了校园垃圾分类回收的必要性,并分别对垃圾的产生量和主要成分进行了研究;在分析对比三种垃圾源头分类方式后得出,学校适合采用”源头细分类”的方式;建立起了垃圾收集负荷的计算模型,并研究了教学区、宿舍区、食堂的垃圾回收模式;最后对校园垃圾分类回收体系的运行提出了建议。     

The Urbanization Pattern of China in the 21st Century

The 21st century is referred to as a "century for cities"or "era for cities", and China has also speeded up its processof urbanization, which will bring massive influence to theeconomic development of the country and also to theworld. Joseph E. Stiglize, a winner of The Nobel Prize onEconomy, said that (the urbanization in China and thedevelopment of high technologies in the United Stateswill be two major subjects with a profound effect to thedevelopment of all mankind in the 21st century) …     

Use of landscape and land use parameters for classification and characterization of watersheds in the mid-Atlantic across five physiographic provinces

The Atlantic Slope Consortium (ASC) is a project designed to develop and test a set of indicators in coastal systems that are ecologically appropriate, economically reasonable, and relevant to society. The suite of indicators will produce integrated assessments of the condition, health and sustainability of aquatic ecosystems based on ecological and socioeconomic information compiled at the scale of estuarine segments and small watersheds. The research mandate of the ASC project is the following:

Using a universe of watersheds, covering a range of social choices, we ask two questions:

• ? How “good” can the environment be, given those social choices?
• ? What is the intellectual model of condition within those choices, i.e., what are the causes of condition and what are the steps for improvement?

As a basis for compiling ecological indicators, a watershed classification system was required for the experimental design. The goal was to develop approximately five categories of watersheds for each physiographic province, utilizing landscape and land use parameters that would be predictive of aquatic resource condition. All 14-digit Hydrologic Unit Code (HUC) watersheds in the Mid-Atlantic region would then be classified according to the regime. Five parameters were utilized for the classification: three land cover categories, consisting of forested, agricultural, and urban, median slope or median elevation, and total variance of land covers in 1-km-radius circles positioned on all stream convergence points in a specified 14-digit?HUC watershed. Cluster analysis utilizing these five parameters resulted in approximately five well-defined watershed classes per physiographic province. The distribution of all watersheds in the Mid-Atlantic region across these categories provides a unique report on the probable condition of watersheds in the region.     

中国省际水风险评价

选取中国31个省(市、自治区)为研究对象,建立了以行政区域为研究尺度的水风险评价指标体系。运用决策分析模型,通过层次分析法与熵值法确定满足主客观条件的综合权重,在此基础上构建模糊识别模型,对2000—2013年中国31个省(市、自治区)水风险水平进行了评估,并从时间和空间两个维度进行分析。结果表明:1)在研究期间,中国水风险水平不断下降,大部分地区从高值、中高值向中值及中低值靠拢;2)3个子系统中,胁迫性风险一直处于上升状态,中国水资源压力较大并有极大可能继续上升,在现有技术条件下,水风险形势严峻;敏感性风险在3个子系统中贡献较低,各地区抵抗风险能力逐步提高;适应性风险稳步下降,适应风险能力提高,但下降速度减缓,表明治理水问题的难度增大;3)各地区风险来源从单一性演变成复合型,风险来源不同且空间分布不均,治理中国水风险需针对各省(市、自治区)风险来源制定针对性政策。     

基于微震活动性参数的矿山灾害风险性评价

微震灾害分级是判别及处理高风险采场的关键。为了预测并防治采空区失稳导致的灾害,结合用沙坝矿引进的IMS微震监测系统,首先统计矿山尺度的微震活动性特征,将主要采场进行分区。然后分析各分区的最大潜在震级及其重现时间、微震扩散率、微震劲度比、能量频次等特征。最后结合采场微震灾害风险性分级标准对各分区风险性进行分级。结果表明,综合考虑微震事件的能量分布特征、空间分布特征、时间分布特征进行灾害风险性分级的结果更为合理。     

基于决策树模型的煤矿安全事故严重程度分析与预测

为将数据挖掘技术应用于煤矿安全管理,通过对我国1999—2015年29 000多条煤矿安全事故数据的研究,系统分析了事故发生的区域、时间、类型和企业信息等因素对事故严重程度的影响及彼此之间的相关性。通过构建决策树分类模型,在给定事故相关信息的基础上,对事故严重程度进行分类预测;基于数据类别不平衡的特点,采用欠采样的抽样方法,同时利用梯度提升的组合分类器来提高分类精度。结果表明,采用的数据挖掘模型在预测不同严重程度的事故上均达到了较高精度。     

气载微塑料的赋存特征、迁移规律与毒性效应研究进展

微塑料作为一种新兴环境污染物,可能会对全球生态圈（水、土壤和空气）和人类健康造成潜在危害.本文综述了气载微塑料的分析方法、赋存特征、迁移规律及其毒性效应与机制等最新研究进展.当前气载微塑料定量表征主要依赖于体视显微镜检,而其定性分析则主要借助傅里叶红外光谱和拉曼光谱技术.气载微塑料遍及全球各大城市、海洋、甚至偏远山区.HYSPLIT4和沉降计算后推气流轨迹分析揭示了气载微塑料的迁移规律.气载微塑料对人体健康风险的影响研究表明,人类（尤其是儿童）能够吸入高丰度微塑料.今后研究应注重开发出适用于气载微塑料的精准、高效和低成本的分析仪器与方法,强化气载微塑料定量数据规范化,并从细胞、组织、器官等层面深入揭示气载微塑料及其复合污染物的毒性效应与机制.     

2013—2015年北京污染频发期细颗粒物重污染成因与天气形势关系的研究

我国重污染呈现愈演愈烈态势,重污染事件在供暖季节（污染频发期）尤为频发.本文利用北京2013—2015年采暖期逐小时PM_2.5浓度数据、再分析资料、气团后向轨迹、气溶胶雷达数据以及探空数据综合分析了北京地区重污染状况,概括了重污染发生时常见的天气形势,探讨了重污染形成原因与天气形势的关系.研究结果表明：2013—2015年采暖期北京发生重污染（日均PM_2.5浓度大于150 μg·m^-3）的天数分别为36、28及35 d,即北京采暖期21.9%的天数受重污染天气影响.2月份重污染事件最为频发,发生频次为27.3%.北京发生重污染事件时,地面被高压控制时,高空500 hPa多东移的槽脊,当位于脊后槽前时,为上升运动,西南风,850 hPa多暖平流,西南风输送暖湿气流,湿度较大,地面偏南风,可能会存在污染物的输送;地面为低压控制时,500 hPa一般为稳定的西风气流或西北气流,低空850 hPa可能存在暖平流,地面常伴随弱的风场辐合,导致污染物累积;当地面为均压场时,高空500 hPa多为脊后槽前的形势,低空无明显冷暖平流,地面等压线稀疏或无等压线,静风天气.这3类结构引发的重污染天数分别占总重污染天数的47.3%、18.2%及34.5%.进一步分析重污染成因与天气形势关系表明：北京地面受高压系统控制时,污染时间持续最长,也最为频发（47.3%）,PM_2.5平均浓度最高可达258.8 μg·m^-3,且常伴随来自西南方向的污染物输送,北京上空1 km附近存在逆温和逆湿.对污染传输路径研究发现：主要存在3条输送通道,①天津-廊坊-北京、②沧州-廊坊-北京、③石家庄-保定-北京.鉴于目前数值模式对天气形势的预报较为成熟,本文对区域重污染过程与天气形势之间的关系研究,有助于为北京地区空气质量的精准预报预警提供科学支持.     

Estimation of the density of a clustered point pattern using a distance method

Distance-based methods use point-to-point distances or random-location-to-point distances in a cloud of points to estimate characteristics of the point pattern. One such characteristics is the density of points. The difficulty with distance-based density estimators is that their distribution depends on the spatial pattern of points. In particular, the distribution of distances is untractable for usual clustered patterns, that are often observed in natural systems. Here, we propose a density estimator for clustered patterns, based on the random-location-to-pth-point distance X _p . An approximate expression for the distribution function, F _p , of X _p was obtained by identifying the first two moments of the count of individuals in disks for a given point process with the first two moments of a negative binomial distribution. The approximate expression of F _p was then used to derive a maximum-likelihood estimator of the intensity of the point process. The quality of the approximation of F _p was assessed for homogeneous Poisson processes (for which the expression of F _p is exact) and for Matérn processes. The intensity estimator based on Matérn processes was then used to estimate tree density in a tree savanna in Mali, and it compared favorably with six robust estimators found in the literature.