基于可靠性理论的事件树分析方法研究

事件树分析过程中事件树的编制和分析方法缺乏系统性,导致实际运用中事件树的编制缺乏可操作性。从目标系统的选择、环节事件逻辑关系的确定、定量分析中基本数据的来源和确定方法等三个问题进行了系统研究,并以可靠性的相关理论为基础,提出"从控制和影响初始事件发展演化的角度,调查分析对初始事件做出响应的安全功能,按系统工作原理对目标系统进行重构,构建目标系统的功能结构图,画出系统的可靠性框图"入手,对"传统的事件树绘制程序"进行修正,解决了事件树分析过程中目标系统的选择、环节事件逻辑关系的确定以及定量分析基本数据的确定方法等问题。修正后的方案对实现事件树的正确编制和系统分析逻辑更清晰,操作指导性更强。     

贮罐类重大危险源三维风险分级模型研究

为了实现重大危险源分级监管,基于风险管理理论,建立贮罐类重大危险源定性三维分级模型和风险定量分级模型。提出风险评价敏感性因素,选取可能性影响因素、严重性影响因素、敏感性影响因素3类风险评价指标。使用层次分析法(AHP)计算贮罐风险分级指标权重。根据风险可接受准则,将贮罐类重大危险源风险等级划分为4级,实现基于三维风险模型的贮罐类重大危险源快速分级。结果表明:用贮罐类重大危险源三维风险分级模型,通过简单数学模型计算贮罐风险值,能为企业提供风险分级标准,有助于实现政府对贮罐类重大危险源分级监管。     

Review of the application of quantum dots in the heavy-metal detection

Heavy-metal contamination is a major concern, as excessive heavy metals produce environmental pollution, and the cumulative effects of heavy metals in vivo pose a major threat to human health. There is an urgent need for a rapid, sensitive, and efficient method for detecting heavy metals. Quantum dots (QDs) are in the category of semiconductor nanocrystals whose radii are less than or close to the exciton Bohr radius. QDs possess a potential in the biological and medical fields to function as a new type of fluorescent marker, because of their unique and tunable photophysical properties, which include broad excitation spectrum, narrow emission spectrum, tunable emission wavelengths, and negligible photobleaching. In recent years, QDs made significant progress in quantitative analysis by providing a new approach for determination of chemical content analysis. The aim of this study was to review the research progress of QD detection of heavy metals in water and consider the challenges and future outlook for QD-based sensors for heavy-metal ions.     

爆炸超压场景下危化品社会风险对允许规划人口密度的影响分析*

为研究危化品重大危险源基于社会风险基准的规划管控影响,采用我国标准规定的定量风险评价方法,TNT当量炸药简化方法,针对最大TNT当量炸药、事故发生总累计频率、人口密度分布控制参数等不同工况条件,对比分析国土开发强度的允许人口密度受社会风险约束影响的变化规律。研究结果表明:人口密度指数分布控制参数Nk与Nb的允许取值随最大TNT当量炸药和事故发生总累计频率降低而提高;确定工况下,允许总人口规模受最大TNT当量炸药影响很小;在最大TNT当量炸药大于100 t或事故发生总累计频率小于1×10-8次/a时可按最大事故场景进行规划控制分析。     

室内空气中的气态多环芳烃的被动采样监测

利用自制被动采样装置,在2011年秋冬季对南京市部分地区室内空气中5种气态多环芳烃(PAHs)(萘、苊烯、苊、芴、菲)进行了为期100d的连续采样检测,被动采样器的采样速率为0.012m3/d,5种PAHs的回收率在63%～105%之间,方法检出限在1.1～2.4ng范围内。结果表明,南京市5处不同室内环境空气中萘的浓度最高,占总量的90%以上。室内环境空气中5种PAHs的总浓度为230～1564ng/m3。住宅内人体对5种PAHs的暴露速率为479～560ng/h。     

地震学综合定量预报方法在华东地区地震预测中的应用研究

本文应用地震学综合定量预报方法,结合区域地震活动特点,在华东地区进行了分区实际预报效能检验.结果表明该方法在华东地区有5个区域通过R值检验,效果较好,有4个区域未能通过R值检验;并对通过检验的区域地震活动趋势进行了分析.     

Soil nitrogen transformations under elevated atmospheric CO₂ and O₃ during the soybean growing season

We investigated the influence of elevated CO₂ and O₃ on soil N cycling within the soybean growing season and across soil environments (i.e., rhizosphere and bulk soil) at the Soybean Free Air Concentration Enrichment (SoyFACE) experiment in Illinois, USA. Elevated O₃ decreased soil mineral N likely through a reduction in plant material input and increased denitrification, which was evidenced by the greater abundance of the denitrifier gene nosZ. Elevated CO₂ did not alter the parameters evaluated and both elevated CO₂ and O₃ showed no interactive effects on nitrifier and denitrifier abundance, nor on total and mineral N concentrations. These results indicate that elevated CO₂ may have limited effects on N transformations in soybean agroecosystems. However, elevated O₃ can lead to a decrease in soil N availability in both bulk and rhizosphere soils, and this likely also affects ecosystem productivity by reducing the mineralization rates of plant-derived residues.     

Two-Compartment Sorption of Phenanthrene on Eight Soils with Various Organic Carbon Contents

Sorption characteristics of phenanthrene (PHE) were studied on eight soils with organic carbon contents spanning over an order of magnitude using phase distribution relationships (PDRs) at 1 h, 48 h, and 720 h contact times. A new algebraic method was employed to describe the sorption characteristics at different time intervals (between 1 h and 48 h, and 1 h and 720 h). It was found that nonlinearity increased with increasing contact time and sorption that occurred in the subsequent time interval following the initial 1 h exhibited stronger isotherm nonlinearity. Sorption coefficients were positively correlated with the organic carbon contents of the soils. Detailed sorption dynamics were also examined on these soils. A two-compartment, first-order model was used to describe the sorption dynamics. The rate constants of the two compartments differed 18–170 times, suggesting the dissimilar sorption behaviors of the mathematically separated compartments. These two compartments were labeled fast and slow sorption compartment according to the rate constants. Calculation showed that the fast compartment accounted for over 80% of the overall sorption at the initial 1 h, while the slow compartment predominated the total sorption in the following 47 h. By combining the discussion of PDRs and sorption dynamics, the contributions of the two compartments to linear and nonlinear sorption were differentiated. The slow sorption compartment made a major contribution to nonlinear sorption and possibly to sequestration of organic pollutants by these soils.     

基于"脱钩"模式的低碳城市评价

由于历史及现状等诸多因素,以二氧化碳减排绝对量为基础的低碳城市评价模式并不适用于中国;本研究从经济发展、物质消耗与污染物排放相互关系的视角,以"脱钩"模式为目标层,经济发展、碳排放、污染物排放与经济发展为准则层,CO2排放等8个具体指标为指标层建立低碳城市评价指标体系,定量描述经济发展过程中单位GDP污染物排放降低的态势,进而表征城市发展过程中的经济、资源、环境变化的历史趋势并反映城市低碳建设现状.针对沈阳市的案例研究表明,沈阳市2001年至2008年总体的生态效率与资源利用效率呈现逐渐提高的态势,沈阳市现阶段的低碳城市建设水平处于"相对脱钩"阶段,与目前中国经济宏观发展态势相符合.本研究表明,"脱钩"评价模式可以避免基于污染物总量的评价模式中忽略经济发展因素而产生的片面性,可以表征中国当前经济高速发展前提下的城市低碳建设水平,为目前的"低碳城市"评价方法提供有益尝试.     

基于负产品投入产出分析的循环经济定量化评价及实证研究

借用投入产出法的矩阵思想，构建了一个部门间以负产品关联的投入产出分析模型。基于此模型建立了衡量研究区域循环经济模式下的各生产部门的收益与贡献以及区域整体的环境效益和经济效益的评价指标。实证研究中，应用上述指标对深圳市南山区月亮湾循环经济产业示范园区进行了相关评价与分析，同时指出了该评价方法的优点与不足。