Process design optimization and risk analysis

Hazard identification and risk assessment are key aspects in process plant design. They are often applied in the final stages of the process at whatever the cost, unless financial constraints are imposed. However, a much better solution would be to introduce risk analysis earlier by including it in earlier stages of the design process, such as when the cost of a plant and the cost of any accidents that may occur are estimated. In this paper, an optimization methodology is proposed, in which both cost and risk (with a deterministic approach) are taken into account, to improve on the current situation. If a decision variable is chosen, an objective function will be established that makes it possible to analyze variations in overall costs, including the cost of the investment and the cost of accidents. This leads to an optimum situation in which costs are kept to a minimum. Of course, this optimization is subject to constraints, the greatest of which is the fact that risk must not exceed tolerated threshold levels. The procedure is explained and two examples, one involving a toxic release and the other a BLEVE/fireball, are used to illustrate it.     

鲁班水库水体营养状态

四川三台鲁班水库属于大型湖库,多年来除具有特色景观作为旅游景点外,主要用于发展水产养殖业。随着时间的延续,养殖规模的不断扩大,湖库的自净能力越来越差,使有机物污染不断加重,水质越来越差,出现富营养化现象,对水环境造成了不利影响。近年来,为了改变湖库水环境质量,调整转化湖库功能,恢复水环境质量,加强了对其水质的监测,其中的营养状态指标是湖库水环境质量的主要评价指标。评价结果,除秋季和冬季个别月份外,其余各月均有测点达到轻度富营养化及中度富营养化。     

玉米自交系氮效率基因型差异的比较研究

采用溶液培养的方法。选用经田间，土壤试验对N反应有典型差异的玉米自交系478，H21，Wu312,Zong31,Baici，在4个供氮水平下（0.04,0.4,2和4nmol/L)，研究了不同基因型玉米苗期氮素吸收，利用的差异及其原因，结果表明：极低N胁迫条件下（０.04mmol/L),总干重的基因型差异是由根系，地上部的共同作用的结果，高N下，总干重是由地上部的差异所决定的（表1），极低供N条件下，4578的总干重最大，且有较高的氮效率，Wu312,Zong31相对较低，478相对较高的氮效率主要来源于吸收效率的差异。该基因型在低N下总吸氮量最高，H21居中，Baici,Zong31相对较低，478相对较高的氮效率主要来源于吸收效率的差异。该基因型在低N下总吸氮量最高，H21居中，Baici,Zong31,Wu312相对较低（图1），吸收效率的差异主要是由于根系全N量的不同所致（图3），而根系全N量的差异主要是由于根系大小不同（表1），在极低氮水平下，不同基因型玉米根系全氮量的变幅比地上部高出28.1%，高N下（4mmol/L)，全N量的变幅比地上部高出15.4%(图2，图3），在0.04mmol/L下，478与Wu312,Zong31的利用效率不存在显著差异（表2）。     

Patterns of animal diversity in different forms of tree cover in agricultural landscapes.

As tropical regions are converted to agriculture, conservation of biodiversity will depend not only on the maintenance of protected forest areas, but also on the scope for conservation within the agricultural matrix in which they are embedded. Tree cover typically retained in agricultural landscapes in the neotropics may provide resources and habitats for animals, but little is known about the extent to which it contributes to conservation of animal species. Here, we explore the animal diversity associated with different forms of tree cover for birds, bats, butterflies, and dung beetles in a pastoral landscape in Nicaragua. We measured species richness and abundance of these four animal taxa in riparian and secondary forest, forest fallows, live fences, and pastures with high and low tree cover. We recorded over 20,000 individuals of 189 species including 14 endangered bird species. Mean abundance and species richness of birds and bats, but not dung beetles or butterflies, were significantly different among forms of tree cover. Species richness of bats and birds was positively correlated with tree species richness. While the greatest numbers of bird species were associated with riparian and secondary forest, forest fallows, and pastures with >15% tree cover, the greatest numbers of bat species were found in live fences and riparian forest. Species assemblages of all animal taxa were different among tree cover types, so that maintaining a diversity of forms of tree cover led to conservation of more animal species in the landscape as a whole. Overall, the findings indicate that retaining tree cover within agricultural landscapes can help conserve animal diversity, but that conservation efforts need to target forms of tree cover that conserve the taxa that are of interest locally. Preventing the degradation of remaining forest fragments is a priority, but encouraging farmers to maintain tree cover in pastures and along boundaries may also make an important contribution to animal conservation.     

喀斯特地区丛枝菌根真菌多样性研究进展

丛枝菌根真菌（Arbuscular Mycorrhizal Fungi,AM真菌）在喀斯特地区生态修复中具有潜在的可利用性,关于喀斯特地区AM真菌多样性以及生态功能的研究已成为近年来的热点问题。本文归纳了喀斯特地区分离出的AM真菌名录,旨在为喀斯特高效生态修复菌种筛选提供支撑材料。综述了喀斯特地区土壤石灰性、营养物质匮乏、空间异质性强,植被逆向演替、植物种类多样等特点对喀斯特地区AM真菌多样性的影响规律,总结了AM真菌对于喀斯特地区土壤结构、营养元素循环、植物抗旱性、植物个体养分吸收、植被演替方面的生理生态功能及作用机理,以期为喀斯特地区AM真菌适生性研究、AM真菌潜在生态功能有效利用、AM真菌-植物共生体系筛选与培育等环节做出指引,为菌根技术在喀斯特生态修复中的应用提供理论基础。未来的研究应进一步深入探究AM真菌多样性影响机制,探讨AM真菌与植物适生性之间的关系,以及加强AM真菌-植物共生体系筛选与培育。     

18650型锂离子电池燃烧特性及火灾危险性评估

为评估18650型锂离子电池的火灾危险性,以3种不同品牌的商品三元18650型锂离子电池为研究对象,采用锥形量热仪在不同辐射热和荷电状态下对3种电池进行了燃烧试验,分析了电池的热释放参数、烟参数、毒性参数和质量损失参数。并在试验的基础上构建了锂离子电池火灾危险性综合评估指标体系,计算了这3种电池在辐射热35kW/m^2及品牌1的18650型锂离子电池在25 kW/m^2条件下的火灾危险指数。结果表明:电池的热参数和毒性参数随电池荷电状态(SOC)和辐射热增大而增大,满电状态下的品牌1电池在辐射热为50 kW/m^2、35 kW/m^2和25 kW/m^2时的热释放速率峰值分别为9.23 kW、8.64 kW和6.26 kW;生烟量随电池SOC和辐射热增大而减小;综合评估得出了3种电池的火灾危险性。     

海水对含水层沉积物中镭解吸的模拟实验

本研究采用莱州湾沿岸含水层中的沉积物,通过渗滤实验模拟镭的解吸过程。结果表明,在典型的地下水流速范围内(0.02~0.30 cm/min),镭同位素(223Ra、224Ra、226Ra)的解吸没有显著变化。在海水与淡水的混合过程中,解吸的镭比活度与水的盐度呈显著的线性正相关关系。当盐度超过海水盐度时(如S=80的卤水中),解吸的镭比活度则趋于最值平台。对比模拟估算的地下水中镭的比活度与莱州湾沿岸实测间隙水中镭的比活度,223Ra和224Ra的结果基本一致,而226Ra的实测结果较模拟估算结果偏小。可能由于含水层中226Ra经反复解吸后得不到母体核素及时补充所致。本研究将为更好地理解镭同位素在含水层中的地球化学行为提供科学依据,为合理地选择量化海底地下水排放(submarine groundwater discharge,SGD)模型的镭端元值提供新的参考视角。     

Environmental monitoring of water resources around a municipal landfill of the Rio Grande do Sul state,Brazil

Environmental Science and Pollution Research - In Brazil, landfills are commonly used as a method for the final disposal of waste that is compliant with the legislation. This technique, however,...     

MS SQL SERVER复制技术在地震前兆数据集成中的应用

基于WINDOWS NT 网络操作系统的MS SQL SERVER复制环境，分析并探讨了SQL SERVER复制技术、 复制模块的参数设置及其在地震前兆数据集成中的应用。 通过实例说明了SQL SERVER复制技术在地震前兆数据集成中应用的可行性。 同时，对复制过程中常出现的事务日志空间问题进行了剖析，并提出了解决办法。 分析结果表明，应用SQL SERVER复制技术进行数据交换、 共享及应用是较为有效的，而且也是可行的。