基于BP网络的建筑安装施工现场安全综合评价的研究

针对目前我国建筑安装施工现场安全评价技术的不成熟和欠科学性的现状 ,笔者分析和综合了目前安全评价技术 ,结合建筑业特点 ,提出了基于BP神经网络的建筑安装施工现场安全评价方法 ,并对该评价模型的原理、方法及算法进行了研究。首先 ,结合建筑安装施工现场安全生产的特点建立评价指标体系 ,随后 ,运用层次分析法确定指标及准则层的权重 ,并运用模糊综合评价法生成评价样本集 ,最后 ,利用样本集训练BP网络 ,待误差满足要求后 ,即可运用训练成功的BP神经网络进行安全评价。     

液化气运输过程中的危险分析

应用各种爆炸后果估计模型对液化气运输过程中的爆炸后果进行了评估，并用ETA分析方法对存在的危险进行了分析，指出了控制措施。     

TraK装置测定废水中的BOD_5

在对废水中的BOD5进行常规分析时,采用化学稀释法操作繁琐,对稀释倍数估计易发生错误。而利用TraK装置测试样品时,无须进行稀释和化学分析。用该装置对标准样品BOD5的测定结果表明:准确度相对误差为-3.3%～4.3%,精密度的相对误差为-3.5%～5.6%。该仪器测试性能可靠,数据准确度、精密度合格。与化学法对照分析表明,相对误差都在容许范围内,即在可接受范围内。     

TNT当量法预测某石化设备爆炸后果评价

以烃化反应器为模拟发生泄漏事故源,泄漏的物料形成爆炸性气体,发生爆炸事故,采用TNT当量法预测爆炸事故后果,通过公式,计算出因爆炸冲击波导致肺出血而引起死亡的概率为0.5的半径.     

A comparative study of US EPA 1996 and 1999 emission inventories in the west Gulf of Mexico coast region, USA

Emission inventory is one of the required inputs to air quality models. To assist in the urban and regional modeling efforts, United States Environmental Protection Agency (EPA) has compiled a National Emission Inventory (NEI) for criterion pollutants, and the precursors of ozone and particulate matter (PM). In December 2002, EPA released the 1999 NEI estimates (NEI99), which represent the most recent national emission data. However, the data sets are not in model-ready format for air quality simulations. This present work converts the NEI99 Final Version 2 data sets into Inventory Data Analyzer (IDA) format and processes the data using the Sparse Matrix Operator Kernel Emissions (SMOKE) modeling system to generate a gridded emission inventory in a domain covering the west Gulf Coast Region, USA. The spatial and diurnal emission characteristics of the gridded emission inventories are then assessed and compared with those of the National Emission Trend 1996 (NET96). The NEI99 database contains more complete emission records in both area and point sources. It is also found that NEI99 data exhibit greater emissions with respect to point and mobile sources but smaller emissions with respect to area sources when compared to the corresponding gridded NET96 data in the same study domain. The most distinct differences between the NEI99 and NET96 databases are CO emission of mobile sources, SO2 emissions of point sources, and VOC/PM/NH3/NOx emissions of area and non-road sources. The gridded NEI99 data show low VOC/NOx ratios (<2-5) in the urban areas of the study domain.     

突发事件机理体系与现代应急管理体制设计

本文为了增加对突发事件的科学认识,提升应急管理的能力水平,首先对突发事件和应急管理的内在机理进行剖析。通过分阶段、划层次地构建"4L-5S"机理分析模型,将二者划归为统一体系,以理清其逻辑内涵;然后,为顺应时代发展特征,满足应急管理的更高要求,实现应急管理工作从非常态协同应对转为常态化职能管理,对现代应急管理体制加以总体设计。从而,突发事件机理体系设计使得我国的突发事件机理研究逐渐过渡至具有阶段性和层次性,现代应急管理体制设计使得我国应急管理整合出具备现代思维理念的逻辑框架。     

官方媒体参与下不同风险感知群体竞争模型及其演化规律

为识别公众风险感知的演化规律和官方媒体参与的作用机制，首先，根据公众的行为表现划分不同风险感知群体，并分析群体间的相互竞争和官方媒体的扰动作用；然后，通过扩展Lotka Volterra模型建立群体间的相互竞争模型；在此基础上，通过推导模型平衡点及其稳定性分析模型演化规律；最后，运用数值仿真考查了官方媒体的参与对模型演化的影响。研究结果表明:模型演化具有3种结果情景，官方媒体参与能够显著改变模型演化的速度和结果。     

Estimating abundance without recaptures of marked pallid sturgeon in the Mississippi River

Abundance estimates are essential for assessing the viability of populations and the risks posed by alternative management actions. An effort to estimate abundance via a repeated mark‐recapture experiment may fail to recapture marked individuals. We devised a method for obtaining lower bounds on abundance in the absence of recaptures for both panmictic and spatially structured populations. The method assumes few enough recaptures were expected to be missed by random chance. The upper Bayesian credible limit on expected recaptures allows probabilistic statements about the minimum number of individuals present in the population. We applied this method to data from a 12‐year survey of pallid sturgeon (Scaphirhynchus albus) in the lower and middle Mississippi River (U.S.A.). None of the 241 individuals marked was recaptured in the survey. After accounting for survival and movement, our model‐averaged estimate of the total abundance of pallid sturgeon ≥3 years old in the study area had a 1%, 5%, or 25% chance of being <4,600, 7,000, or 15,000, respectively. When we assumed fish were distributed in proportion to survey catch per unit effort, the farthest downstream reach in the survey hosted at least 4.5–15 fish per river kilometer (rkm), whereas the remainder of the reaches in the lower and middle Mississippi River hosted at least 2.6–8.5 fish/rkm for all model variations examined. The lower Mississippi River had an average density of pallid sturgeon ≥3 years old of at least 3.0–9.8 fish/rkm. The choice of Bayesian prior was the largest source of uncertainty we considered but did not alter the order of magnitude of lower bounds. Nil‐recapture estimates of abundance are highly uncertain and require careful communication but can deliver insights from experiments that might otherwise be considered a failure.     

湖北省PM2.5与PM10比值分析及PM2.5时空分布特征研究

基于2012年-2014年湖北省大气污染物监测数据,通过数据反演方法,得到湖北省17个城市的PM2.5年均浓度.利用ArcGIS绘制出各城市不同年份的颗粒物浓度空间分布图,并对其进行分析.结果表明,2012年-2014年间,湖北省17个城市PM2.5与PM10年均浓度比值为0.66,PM2.5年均浓度超出国家二级标准,整体呈现上升趋势.城市方面,在多数城市PM2.5与PM10浓度上升的同时,仅武汉、黄冈和天门3个城市颗粒物浓度2014年较2013年有所下降,且武汉市PM2.5浓度下降率达12.8%,表明武汉市近两年来采取的政策措施具有较好的可行性和有效性.     

城区机动车尾气排放量与雾霾关系研究

近年来雾霾严重影响到了人们正常的生活和身体健康,许多报道都将机动车尾气看做是雾霾的"元凶".G20期间,在柯桥区及周边区域几乎全部企业都处于停产状态下,根据柯桥区域机动车限行前后的数量与空气报告得出的数据显示:PM2.5浓度没有随着机动车减少而降低,汽车的尾气对PM2.5浓度的影响有限,机动车尾气是雾霾的"元凶"的说法有些言过其实.