2004—2017年浙江省较大以上生产安全事故统计分析

为充分探究浙江省生产安全事故发生规律,以2004—2017年浙江省生产安全事故为研究对象,从事故发生的时间关系、区域分布、行业分布、事故类型分布等方面对全省总体、工矿商贸领域、化工领域、典型危险作业4个分类的较大以上事故特点进行了剖析研究;并从政府监管的角度,提出事故防范的措施和建议。     

Use of Predictive Weather Uncertainties in an Irrigation Scheduling Tool Part II: An Application of Metrics and Adjoints

We apply predictive weather metrics and land model sensitivities to improve the Colorado State University Water Irrigation Scheduler for Efficient Application (WISE). WISE is an irrigation decision aid that integrates environmental and user information for optimizing water use. Rainfall forecasts and verification performance metrics are used to estimate predictive rainfall probabilities that are used as input data within the irrigation decision aid. These input data errors are also used within a land model sensitivity study to diagnose important prognostic water movement behaviors for irrigation tool development purposes simultaneously performing the analysis in space and time. Thus, important questions such as “how long can a crop water application be delayed while maintaining crop yield production?” are addressed by evaluating crop growth stage interactions as a function of soil depth (i.e., space), rainfall events (i.e., time), and their probabilistic uncertainties. Editor’s note : This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series.     

基层环境统计年报中的问题及建议

环境统计工作是环境保护工作中的基础,是各级政府和环境保护行政主管部门制定环境保护政策和计划、加强环境监督管理和污染防治的重要依据。本文结合日常工作经验,就目前基层环境统计工作中存在的问题进行探讨,并提出一些建议。     

重庆市大气污染物的空间统计分析

利用空间统计分析方法(spatial statistics analysis),借助GIS,分析了重庆市3种主要大气污染物TSP,SO₂和NO_x质量浓度在空间上的分布特点.研究表明,在"九五"期间和2002年2个时期,重庆市大气污染物在空间上均呈不均衡分布.整体上,SO₂的空间自相关性很强,属集中分布模式;TSP的空间自相关性较弱,属于随机分布模式;NO_x处于二者之间.局部相关性分析表明,大部分区县的大气污染物之间相关性较弱.此外,利用缓冲区和内插浓度表面法分析了2个时期的污染物质量浓度随离行政中心距离变化的趋势,发现ρ(TSP)和ρ(SO₂)在各地带内均有明显削减,而ρ(NO_x)削减不显著;ρ(SO₂)和ρ(NO_x)随距行政中心距离增大下降,但ρ(TSP)随距离增大而增加.3种污染物质量浓度都在离行政中心50～60 km的地带发生明显变化,由此得出目前重庆市大气污染物空间分布的特征距离为50～60km.      

街道峡谷内汽车排放污染物浓度分布的观测与数值模拟

在上海某典型街道峡谷内按一定的空间布点,在一定时段内同时对各布点进行采样并做一氧化碳浓度分析,同时记录车辆种类、车流量、气象条件等,分析街道峡谷内污染物浓度的分布.运用风向频率加权(WDFW)方法,结合大气流动和污染物扩散的CFD模型进行数值模拟计算.结果表明,数值模拟结果和现场观测结果较吻合,建筑物低的一侧污染物浓度远高于建筑物高的一侧污染物浓度,两侧的污染物浓度随着高度的增加而降低.     

变频控制DO下SBR硝化反应控制参数及节能的中试研究

根据微生物好氧反应的需氧量调节曝气量在当今能源紧缺的形势下具有十分重要的意义.为了研究曝气量大小对SBR实时控制参数pH、DO的影响,采用变频器调节曝气量以控制系统不同的DO浓度,以60 m3中试SBR反应器处理北京市北小河污水处理厂城市污水,考察了硝化过程中pH值、DO与有机物去除及硝化过程的相关性,并引入了新的控制参数--变频频率f.试验结果表明,控制溶解氧浓度较低时,pH值不能作为硝化结束的控制参数,但可根据变频频率f的特征点判断硝化反应的结束;控制溶解氧为3.0 mg/L和4.0 mg/L时,DO、pH值、变频频率f都可作为硝化结束的控制参数,同时,变频控制可有效降低单位时间内风机的能耗.     

回灌运行参数对新鲜垃圾渗滤液的影响研究

采用模拟试验装置考察回灌频率与回灌水力负荷对新鲜垃圾柱渗滤液的影响,试验结果表明:高频率回灌将导致新鲜垃圾柱渗滤液初期酸化阶段的低pH值和甲烷化阶段的高pH值。高水力负荷将导致新鲜垃圾柱渗滤液pH值下降。因此在新鲜垃圾填埋单元自身回灌初期应采取低频率小水力负荷。     

地铁运行引起的地面振动实测及传播规律分析

对地铁线路某区间段的地面振动进行实测,采集不同测线和不同测点处的水平方向、竖直方向加速度,并转化为傅里叶幅值谱对其进行衰减规律分析。利用公式将加速度记录换算为振级和分频振级,参照相关的国家标准分析不同距离处的振级和频率成分。对比同一加速度记录中的两对开方向列车引起的地面振动,进一步分析振动衰减的规律。所得到的结果可供地面建筑的隔振减振及城市轨道的规划和设计参考。     

Predicting land cover using GIS, Bayesian and evolutionary algorithm methods

Modelling land cover change from existing land cover maps is a vital requirement for anyone wishing to understand how the landscape may change in the future. In order to test any land cover change model, existing data must be used. However, often it is not known which data should be applied to the problem, or whether relationships exist within and between complex datasets. Here we have developed and tested a model that applied evolutionary processes to Bayesian networks. The model was developed and tested on a dataset containing land cover information and environmental data, in order to show that decisions about which datasets should be used could be made automatically. Bayesian networks are amenable to evolutionary methods as they can be easily described using a binary string to which crossover and mutation operations can be applied. The method, developed to allow comparison with standard Bayesian network development software, was proved capable of carrying out a rapid and effective search of the space of possible networks in order to find an optimal or near-optimal solution for the selection of datasets that have causal links with one another. Comparison of land cover mapping in the North-East of Scotland was made with a commercial Bayesian software package, with the evolutionary method being shown to provide greater flexibility in its ability to adapt to incorporate/utilise available evidence/knowledge and develop effective and accurate network structures, at the cost of requiring additional computer programming skills. The dataset used to develop the models included GIS-based data taken from the Land Cover for Scotland 1988 (LCS88), Land Capability for Forestry (LCF), Land Capability for Agriculture (LCA), the soil map of Scotland and additional climatic variables.     

Sensitivity and Uncertainty of Ground‐Water Discharge Estimates for Semiarid Shrublands1

Abstract: We proposed a step‐by‐step approach to quantify the sensitivity of ground‐water discharge by evapotranspiration (ET) to three categories of independent input variables. To illustrate the approach, we adopt a basic ground‐water discharge estimation model, in which the volume of ground water lost to ET was computed as the product of the ground‐water discharge rate and the associated area. The ground‐water discharge rate was assumed to equal the ET rate minus local precipitation. The objective of this study is to outline a step‐by‐step procedure to quantify the contributions from individual independent variable uncertainties to the uncertainty of total ground‐water discharge estimates; the independent variables include ET rates of individual ET units, areas associated with the ET units, and precipitation in each subbasin. The specific goal is to guide future characterization efforts by better targeting data collection for those variables most responsible for uncertainty in ground‐water discharge estimates. The influential independent variables to be included in the sensitivity analysis are first selected based on the physical characteristics and model structure. Both regression coefficients and standardized regression coefficients for the selected independent variables are calculated using the results from sampling‐based Monte Carlo simulations. Results illustrate that, while as many as 630 independent variables potentially contribute to the calculation of the total annual ground‐water discharge for the case study area, a selection of seven independent variables could be used to develop an accurate regression model, accounting for more than 96% of the total variance in ground‐water discharge. Results indicate that the variability of ET rate for moderately dense desert shrubland contributes to about 75% of the variance in the total ground‐water discharge estimates. These results point to a need to better quantify ET rates for moderately dense shrubland to reduce overall uncertainty in estimates of ground‐water discharge. While the approach proposed here uses a basic ground‐water discharge model taken from an earlier study, the procedure of quantifying uncertainty and sensitivity can be generalized to handle other types of environmental models involving large numbers of independent variables.