RASTER-BASED HYDROLOGIC MODELING OF SPATIALLY-VARIED SURFACE RUNOFF1

ABSTRACT: The proliferation of watershed databases in raster Geographic Information System (GIS) format and the availability of radar-estimated rainfall data foster rapid developments in raster-based surface runoff simulations. The two-dimensional physically-based rainfall-runoff model CASC2D simulates spatially-varied surface runoff while fully utilizing raster GIS and radar-rainfall data. The model uses the Green and Ampt infiltration method, and the diffusive wave formulation for overland and channel flow routing enables overbank flow storage and routing. CASC2D offers unique color capabilities to display the spatio-temporal variability of rainfall, cumulative infiltrated depth, and surface water depth as thunderstorms unfold. The model has been calibrated and independently verified to provide accurate simulations of catchment response to moving rainstorms on watersheds with spatially-varied infiltration. The model can accurately simulate surface runoff from flashfloods caused by intense thunderstorms moving across partial areas of a watershed.     

Inhibition and recovery of nitrification in treating real coal gasification wastewater with moving bed biofilm reactor

Moving bed biofilm reactor (MBBR) was used to treat real coal gasification wastewater. Nitrification of the MBBR was inhibited almost completely during start-up period. Sudden increase of influent total NH3 concentration was the main factor inducing nitrification inhibition. Increasing DO concentration in the bulk liquid (from 2 to 3 mg/L) had little e ect on nitrification recovery. Nitrification of the MBBR recovered partially by the addition of nitrifying sludge into the reactor and almost ceased within 5 days. Nitrification ratio of the MBBR achieved 65% within 12 days by increasing dilute ratio of the influent wastewater with tap water. The ratio of nitrification decreased to 25% when influent COD concentration increased from 650 to 1000 mg/L after nitrification recovery and recovered 70% for another 4 days.     

我国工伤事故死亡率分析及其ARIMA预测

对我国工伤事故死亡率的历史数据进行分析,介绍ARIMA模型预测法。根据统计学理论,运用ARIMA模型,借助相关软件预测我国工伤事故死亡率,可知未来几年,工伤事故的千人死亡率总体上呈逐年下降的趋势;与移动平均法、指数平滑法预测结果作比较,可知ARIMA模型预测效果最佳;同时,由于影响工伤事故的因素很多,与长期预测相比,ARIMA模型更适合于对工伤事故死亡率作短期预测。     

新疆“十三五”城市空气质量评价分析

“十三五”是新疆经济、社会和环境发展的关键期.基于2015-2020年新疆14个城市空气质量年平均数据,采用三年滑动平均方法对新疆“十三五”空气质量进行评价分析.结果 表明:全区空气质量优劣依次是北疆＞东疆＞南疆,其中乌鲁木齐市三年滑动年均优良天数比例呈逐年上升趋势,而和田市与之相反,呈下降趋势,且三年滑动年均下降率达...     

汽车整车结构侧面耐撞性有限元数值模拟

目的研究汽车结构侧面主要承载部件的耐撞性,参考我国碰撞法规和ECE R95,根据国内某SUV汽车的参数和相关标准建立整车有限元模型和移动可变形壁障模型(MDB),对其进行数值模拟,为结构的优化设计提供参考。方法利用Hyper Mesh前处理将CAD模型转化为CAE有限元模型,输出k文件,并通过LS-DYNA大变形有限元仿真软件对其耐撞性进行计算。结果仿真结果显示,在汽车侧面碰撞过程中,B柱和车门等主要承载部件发生了较大的变形,B柱变形量为116.6 mm,车门的变形量为190 mm,其值符合标准要求,在碰撞结束后保证了足够的乘员空间。结论该车有较好的侧面耐撞性,且得出的碰撞数值模拟结果可为该车的结构设计提供参考。     

井下移动热源对巷道局部风流温度影响规律研究

为了研究煤矿井下热源对巷道局部风流温度的影响,通过搭建实验平台以及建立数值模型,采用实验和数值模拟的方法,分析井下固定和移动热源对巷道局部风流温度的影响规律。研究结果表明:对比实验和数值模拟固定热源对巷道局部风流温度的影响,结果显示二者总体温度变化趋势一致性较好,验证了数学模型的正确性;井下热源移动速度不同时,顺风移动速度越大,对巷道局部温度影响越大,且巷道局部温度相对升高;逆风移动速度越大,对巷道局部温度影响越小,且巷道局部温度相对降低。     

指数加权移动平均控制图在实验室中的应用及与其他质控图比较

阐述了指数加权移动平均(EWMA)控制图在环境分析实验室中的应用,并与休哈特控制图和Westgard多规则对于不同偏移量的ARL值作了比较.结果表明,EWMA控制图在检验不准确度,尤其在微小偏移上的优势值得推广.     

Evaluation of A Sampling Strategy for Estimation of Long-term Pm2.5 Exposure for Epidemiological Studies

As part of the European Community Respiratory Health Survey (ECRHS) PM_2.5 (particles collected with an upper 50% cut point of 2.5 μm aerodynamic diameter) was measured using an EPA-WINS (Environmetal Protection Agency Well Impactor Ninety-six) sampler. The monitoring schedule was restricted to 7 days per month for one year. Simultaneously, during this one year study period a collocated Harvard Impactor (HI) was run on a daily basis in Erfurt, Germany. Here we validated the reliability of annual, seasonal and monthly means estimated using the ECRHS scheme (measurements taken less than 25% of the whole study period) with the ‘true’ long-term averages, which were estimated using all available daily means.The daily PM_2.5 means, obtained by both instruments operated in parallel, were only slightly different (the mean difference between EPA-WINS and HI was 1.8 μg m⁻³ and 2.8 μg m⁻³ for the winter means). The values obtained by the two instruments were highly correlated (r = 0.95).In view of that negligible difference, no additional bias was seen with respect to the annual and the winter means estimated by the two different sampling strategies (the difference was 1.7 μg m⁻³ and 2.7 μg m⁻³, respectively). Monthly means, however, can only be considered to be a crude estimate that may substantially under- or overestimate the true monthly mean value.     

2002—2016年北京市PM10浓度时间变化特征

以北京市2002—2016年PM₁₀日均浓度序列数据为基础,结合小波分析、Mann-Kendall检验、滑动t检验等分析方法,研究PM₁₀浓度随时间变化的周期性、趋势性及突变性特征。结果表明：PM₁₀日均浓度变化具有较典型的季节周期性,主周期为300 d左右,次周期为150 d左右。不同周期分析结果显示,PM₁₀污染春季最高,冬季次高,夏末秋初最低。总体上,PM₁₀浓度以平均每年约4 μg/m³的速率递减。2009年以前PM₁₀浓度呈波动变化,降低趋势不显著,2009年1月为序列的突变点,突变后呈显著下降趋势。     

移动床生物膜反应器预处理含酚废水

采用两级移动床生物膜反应器（MBBR）预处理高挥发酚含量的石化厂汽提净化水,考察了HRT和DO对废水中挥发酚和COD去除效果的影响。实验结果表明：在两级MBBR总HRT为10 h、MBBR中部废水DO 为1~3 mg/L的条件下, 装置连续运行处理ρ（挥发酚）=110~201 mg/L、COD=644~1 827 mg/L、BOD₅/COD=0.15~0.69的废水,两级MBBR处理后出水平均ρ（挥发酚）为17.6 mg/L,挥发酚去除率达87.9%;平均COD为745 mg/L,COD去除率为32.7%;出水BOD₅/COD平均为0.68,表明经过两级MBBR处理后,废水的可生化性有所提高,有利于废水的后续生化处理。