3-D dispersion model for simulation of accidental toxic gas releases in a metropolitan area

Computational fluid dynamic (CFD) simulations were performed to assess the potential chlorine leak scenario in the super-urban area of South Korea, where the human population density is very high and numerous buildings exist near operational water treatment facilities. Flame acceleration simulator (FLACS) was used to predict the consequence from accidental chlorine releases out of one of the water treatment facilities for the nearby area having a size of 5 km × 3 km approximately. The ability to precisely implement 3-D geometries is crucial for a successful 3-D simulation. Thus, a method was proposed to rapidly and accurately implement geometry by importing computer aided-design (CAD) files provided by a government agency, and processing them using Auto CAD and MicroStation software programs. An accidental release from an 18-ton tank was simulated with three different wind directions to determine the expected evacuation distances. Results from the study showed that the endpoint distances varied depending on the density and arrangement of the buildings. Moreover, we employed physical barriers with varying heights for mitigating the effects of toxic gas releases and simulated how effectively they decreased the concentration of released chlorine.     

浓密尾矿管道输送的研究现状及展望

为掌握浓密尾矿管道输送中的流动规律及阻力特性,对国内外现有研究成果进行了综述,以尾矿颗粒的粒径尺寸和分布特征为切入点,分析了颗粒-颗粒、颗粒-流体间的相互作用,提出将浓密尾矿管道输送划分为均质结构流和复合流动两种模式,分别对不同模式下浆体流变性质、颗粒运移行为、流动型态及阻力特性方面的研究成果和最新进展进行了评述。结果表明:均匀细颗粒(d dc)浓密尾矿可视为由细颗粒介质与离散粗颗粒组成的复合流体,粗颗粒具有"剪切沉降"效应,介质屈服应力较小(τy<5τyc)时,浆体在管道内分层流动,管流阻力可通过两层流模型进行分析。     

共同沟工艺及给排水设计的几点探讨

我国在工程设计中越来越多地采用共同沟工艺,但尚未有国家层面的标准化的相关规范,因此现阶段的工艺设计在给排水方面需参照国外及国内已兴建的共同管沟,尽可能全面地考虑工程设计中会碰到的问题,由此提出一些设计理念。     

阻尼隔声板在噪声控制工程上的应用

对隔声材料的隔声功能进行了分析,根据两种以上不同质的复合材料可避开各自的阻隔波谷,能更有效地提高阻隔宽频噪声的总体性能的声学原理,提出了安装有阻尼层的隔声板,可有效提高隔声板的隔声量。     

某输出缓冲器的失效分析

本文通过对某输出缓冲器在质量一致性检验中的ESD考核环节失效的情况进行分析,找到了产品测试系统的异常情况,通过此次分析,进一步发现该产品的ESD保护设计一直以来存在的问题。文中不仅给出了失效机理,同时提出了改进措施并加以验证。此次失效分析对于同类器件的ESD保护设计,提高其可靠性具有一定的借鉴意义。     

Effluents from MBT plants: Plasma techniques for the treatment of VOCs

Mechanical–biological treatments (MBTs) of urban waste are growing in popularity in many European countries. Recent studies pointed out that their contribution in terms of volatile organic compounds (VOCs) and other air pollutants is not negligible. Compared to classical removal technologies, non-thermal plasmas (NTP) showed better performances and low energy consumption when applied to treat lowly concentrated streams. Therefore, to study the feasibility of the application of NTP to MBTs, a Dielectric Barrier Discharge reactor was applied to treat a mixture of air and methyl ethyl ketone (MEK), to simulate emissions from MBTs. The removal efficiency of MEK was linearly dependent upon time, power and specific input energy. Only 2–4% of MEK was converted to carbon dioxide (CO₂), the remaining carbon being involved in the formation of byproducts (methyl nitrate and 2,3-butanedione, especially). For future development of pilot-scale reactors, acting on residence time, power, convective flow and catalysts will help finding a compromise between energy consumption, desired abatement and selectivity to CO₂.     

Double-dipping in environmental markets

There is an increasing tendency to use markets to induce the provision of environmental services. As such markets increase in scope, potential market participants might sell multiple environmental services. The question we consider here is whether participants in such markets should be allowed to sell credits in more than one market simultaneously. Some have argued in favor of such “double-dipping”, because it would make the provision of environmental services more profitable. In practice however, most programs do not allow double-dipping. We show that if the optimal level of pollution abatement is sought, then double-dipping maximizes societal net benefits. However, if pollution policies are set in a piecemeal fashion, then the caps for each market are unlikely to be optimal and, in this second-best setting, a policy prohibiting double-dipping can lead to greater social net benefits. We explore conditions under which a single-market policy is preferred, or equivalently, where piecemeal policies are likely to yield particularly inefficient outcomes.     

高速公路生态型声屏障评价指标体系研究

以交通部＂西部高速公路生态型声屏障技术应用研究＂课题为依托,开展高速公路生态型声屏障评价指标体系研究。基于AHP层次分析法,提出了由功能性、环保性、景观性以及经济性4个准则层指标和23个具体评价指标构成的一套高速公路生态型声屏障评价指标体系。工程应用结果表明,该体系能客观地反映高速公路生态型声屏障特征,评价结果更趋合理...     

苏州城区路面降雨径流污染特征分析研究

通过对苏州典型商住区和文教区路面径流水质的采样分析探讨了道路降雨径流的污染特征.结果显示不同功能区径流水质差异较大,商住区各污染物浓度均高于文教区.径流污染物浓度一般在降雨初期较高,往后逐渐下降并趋于平稳.SS和COD、Pb等都有较强的相关性.各污染物的初期效应明显,商住区初始冲刷效应较强;重金属物质的冲刷强度要大于其他污染物.降雨强度是影响初始冲刷效应的主要因素,强度较大的降雨初期冲刷效应明显.     

福建省环保投资对工业废水污染控制的影响分析

依据福建省2006-2011年环保投资的相关统计数据,对水污染治理投资和工业废水污染控制的关系进行深入分析,结果表明单位GDP水污染治理投资与工业废水排放量之间呈负相关。并指出福建省环境污染治理投资总量不足,单位GDP水污染治理投资比例偏低等问题,并针对这些问题提出应制定水污染治理投资规划,发展生态生产力并实施过程治理投资,使水污染得到真正有效的控制。