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471.
A new model entitled the coupled mechanical-hydraulic-gaseous effect and biochemical degradation for municipal solid waste (MSW) is proposed to simulate and predict the MSW settlement in this study. The coupled model can be used to simulate and predict the distributions of gas and water pressure as well as total waste settlement. Model verification indicates that because of degradation, the excess pore gas pressure increases rapidly and reaches a peak value in a short time, and then it dissipates gradually. But the excess pore water pressure may not always increase at the beginning, which depends on hydraulic conductivity of MSW. Dissipation of the excess pore water pressure is slower than that of the excess pore gas pressure. A waste settlement experiment was conducted in the laboratory using a synthetic MSW. The data was used to verify the developed model, which gave satisfactory results. Based on the experimental results, a new formula is proposed to simulate biochemical degradation. 相似文献
472.
Povinec PP Chudý M Sivo A Simon J Holý K Richtáriková M 《Journal of environmental radioactivity》2009,100(2):125-130
Radiocarbon variations in the atmospheric CO(2) with attenuating amplitudes and decreasing mean values with typical maxima in summer and minima in winter have been observed since 1967 in two localities of Slovakia, in Bratislava and Zlkovce, situated about 60 km NE from Bratislava, only 5 km from the Bohunice Nuclear Power Plant (NPP). The (14)C record in Bratislava has been influenced mainly by fossil CO(2) emissions, in contrast to the Zlkovce record which has been more variable, as it has clearly been affected by operation of the Bohunice NPP. However, during specific meteorological conditions with NE transport of air masses to Bratislava, the effect of the Bohunice NPP has been visible in Bratislava as well. Maximum (14)C concentrations (up to 120% above a natural background) were observed around A1 NPP which used CO(2) with admixture of air as a cooling agent. The (14)C concentrations around four pressurized light water reactors were up to 30% above the background. The Delta(14)C values in the heavily polluted atmosphere of Bratislava were up to 10% and at Zlkovce up to 5% lower than the European clean air represented by the Jungfraujoch Delta(14)C data. Later the Delta(14)C values were similar at both sites, and from 2003 they were close to the European clean air levels. The observed Delta(14)C behaviour in the atmosphere provides a unique evidence of decreased fossil fuel CO(2) emissions in the region, as well as the long-term effect of the Bohunice NPP on the Bratislava and Zlkovce stations. The estimated annual radiation doses to the local public due to digestion of radiocarbon contaminated food have been estimated to be around 3 microSv. 相似文献
473.
烟塔排烟电厂大气影响预测分析 总被引:1,自引:0,他引:1
在系统分析我国烟塔排烟电厂大气影响评价及其相关研究成果的基础上,指出应关注的几个问题,并结合烟塔排烟电厂的负荷变化特点提出了解决问题的基本思路及需要重点研究的专题。 相似文献
474.
障碍物场中预混燃烧火焰的数值模拟 总被引:4,自引:0,他引:4
利用k-ε湍流模型和拉切滑(SCASM)预混燃烧模型,对障碍物场中预混燃烧火焰进行了三维空间数值模拟。通过对控制方程添加不同的源项以反映障碍物对流场的影响,采用交错网格控制容积法将计算区域进行离散,用SIMPLE算法求解离散控制方程。模拟结果表明,障碍物的存在改变了燃烧流场的结构,成为加速燃烧甚至诱导爆炸过程的不稳定因素。该研究结果对有效预测障碍物场中火焰走势及其流场的分布情况,加强人们对火焰传播规律的认识,对预防工业灾害有重要参考价值。 相似文献
475.
为明确正念对应急疏散行为的影响机制,提高应急疏散效率,构建包含应急正念、风险感知、自我效能、掩蔽效应和应急疏散行为的概念模型,基于调查问卷结果,利用结构方程模型进行实证研究。研究结果表明:正念、风险感知和自我效能对应急疏散行为存在正向影响,正念通过风险感知和自我效能对应急疏散行为产生部分中介效应;掩蔽效应在自我效能影响应急疏散行为过程中具有显著调节作用;正念通过风险感知能力提高自我效能,进一步对应急疏散行为产生影响。研究结果可为缓解突发事件带来的不良情绪及压力,增强个体自信程度及风险感知能力,提高应急疏散效率提供参考和借鉴。 相似文献
476.
为使事故致因“2-4”模型(24Model)在追溯事故原因和制定事故预防对策时取得更好的应用效果,有必要对24Model的内涵进行科学解析。通过文献分析和对比研究,阐述24Model的逻辑结构、原因模块的科学内涵、主要特点。研究结果表明:24Model的主要理论基础,一是HEINRICH、BIRD等提出与改进的多米诺骨牌系列模型,二是REASON提出、SHAPPELL等具体化的瑞士奶酪系列模型和人因分类系统,三是STEWART提出的卓越安全管理模型;静态24Model的逻辑结构以因果关系建立,它属于因果顺序类事故致因模型;静态24Model中事故的直接、间接、根源、根本原因的含义可以从上述3大类事故致因模型、管理体系标准和安全文化的定义中找到根据;动态24Model靠行为演化关系建立逻辑结构,其充分表达自身的系统性、动态性、非线性,并且依靠组织行为即影响行为、个体行为即操作行为,构成一个行为演化系统。 相似文献
477.
478.
479.
Marcela Rojas Felipe Quintero Witold F. Krajewski 《Journal of the American Water Resources Association》2020,56(4):568-585
This paper explores the performance of the analysis‐and‐assimilation configuration of the National Water Model (NWM) v1.0 in Iowa. The NWM assimilates streamflow observations from the United States Geological Survey (USGS), which increases the performance but also limits the available data for model evaluation. In this study, Iowa Flood Center Bridge Sensors (IFCBS) data provided an independent nonassimilated dataset for evaluation analyses. The authors compared NWM outputs for the period between May 2016 and April 2017, with two datasets: USGS streamflow and velocity observations; Stage and streamflow data from IFCBS. The distribution of Spearman rank correlation (rs), Nash–Sutcliffe efficiency (E), and Kling–Gupta efficiency (KGE) provided quantification of model performance. We found the performance was linked with the spatial scale of the basins. Analysis at USGS gauges showed the strongest performance in large (>10,000 km2) basins (rs = 0.9, E = 0.9, KGE = 0.8), with some decrease at small (<1,000 km2) basins (rs = 0.6, E = ?0.25, KGE = ?0.2). Analysis with independent IFCBS observations was used to report performance at large basins (rs = 0.6, KGE = 0.1) and small basins (rs = 0.2, KGE = ?0.4). Data assimilation improves simulations at downstream basins. We found differences in the characterization of the model and observed data flow velocity distributions. The authors recommend checking the connection of USGS gauges and NHDPlus reaches for selected locations where performance is weak. 相似文献
480.
Michelle Platz Michelle Simon Michael Tryby 《Journal of the American Water Resources Association》2020,56(2):283-296
Stormwater infrastructure designers and operators rely heavily on the United States Environmental Protection Agency’s Storm Water Management Model (SWMM) to simulate stormwater and wastewater infrastructure performance. Since its inception in the late 1970s, improvements and extensions have been tested and evaluated rigorously to verify the accuracy of the model. As a continuation of this progress, the main objective of this study was to quantify how accurately SWMM simulates the hydrologic activity of low impact development (LID) storm control measures. Model performance was evaluated by quantitatively comparing empirical data to model results using a multievent, multiobjective calibration method. The calibration methodology utilized the PEST software, a Parameter ESTimation tool, to determine unmeasured hydrologic parameters for SWMM’s LID modules. The calibrated LID modules’ Nash–Sutcliffe efficiencies averaged 0.81; average percent bias (PBIAS) ?9%; average ratio of root mean square error to standard deviation of measured values 0.485; average index of agreement 0.94; and the average volume error, simulated vs. observed, was +9%. SWMM accurately predicted the timing of peak flows, but usually underestimated their magnitudes by 10%. The average volume reduction, measured outflow volume divided by inflow volume, was 48%. We had more difficulty in calibrating one study, an infiltration trench, which identified a significant limitation of the current version of the SWMM LID module; it cannot simulate lateral exfiltration of water out of the storage layers of a LID storm control measure. This limitation is especially severe for a deep LIDs, such as infiltration trenches. Nevertheless, SWMM satisfactorily simulated the hydrologic performance of eight of the nine LID practices. 相似文献