火灾模拟结果误差分析的函数分析法

火灾试验结果和模拟预测结果常能表达成关于时间变化的曲线,为定量描述两种随时间变化曲线间相符合的程度,引入误差分析的函数分析法.采用适合于低Mach数流修正的N-S方程描述烟气的输运过程,使用大涡模拟和Smagorinsky亚格子模型,对封闭空间内的火灾过程进行数值模拟;对其计算结果的分析表明,函数分析法能定量对模拟预测曲线与试验曲线间的差别进行描述,模是两曲线值大小的相对误差的度量,余弦是两曲线形状相似程度的度量.     

Sublethal impact of paraquat on the life span and parasitic behavior of Diaeretiella rapae M’Intosh

This study focuses on assessing the impact of sublethal doses of paraquat on the survival, the emergence, the life span and the parasitic behavior of Diaeretiella rapae M’Intosh (Hymenoptera: Braconidae). The impact of sublethal doses was measured at room temperature using different densities of the cabbage aphid Brevicoryne brassicae. The results reveal that the field dose of paraquat caused 100% mortality in D. rapae. The percentage emergence of D. rapae decreased from 80.5% in the control group to 71.5% when treated with the lowest concentration of paraquat. Similarly, the life span of parasitoids that emerged from the mummy treated with paraquat also decreased significantly. Oviposition capability and ovipositor thrusting frequency of D. rapae also treated with sublethal dose paraquat decreased significantly along with a shortened patch residence time in the foraging area.     

The impact of nitrogen deposition on acid grasslands in the Atlantic region of Europe

A survey of 153 acid grasslands from the Atlantic biogeographic region of Europe indicates that chronic nitrogen deposition is changing plant species composition and soil and plant-tissue chemistry. Across the deposition gradient (2-44 kg N ha⁻¹ yr⁻¹) grass richness as a proportion of total species richness increased whereas forb richness decreased. Soil C:N ratio increased, but soil extractable nitrate and ammonium concentrations did not show any relationship with nitrogen deposition. The above-ground tissue nitrogen contents of three plant species were examined: Agrostis capillaris (grass), Galium saxatile (forb) and Rhytidiadelphus squarrosus (bryophyte). The tissue nitrogen content of neither vascular plant species showed any relationship with nitrogen deposition, but there was a weak positive relationship between R. squarrosus nitrogen content and nitrogen deposition. None of the species showed strong relationships between above-ground tissue N:P or C:N and nitrogen deposition, indicating that they are not good indicators of deposition rate.     

新型树脂对氯酚类物质的吸附研究

合成了乙酰氯修饰树脂NDA-O,与Purolite公司的MN-200相比,合成的树脂比表面积较小,但酸性官能团较多.用两种树脂吸附2-氯酚、4-氯酚和2,4-二氯酚发现,吸附结果可以用Langmuir和Freundlich等温吸附方程很好地模拟,合成的NDA-O对3种氯酚类物质的吸附能力优于MN-200.两种树脂对氯酚类物质的吸附量随着温度的升高而减少,表明吸附是放热过程,同时对氯酚类物质的吸附焓变随着吸附量的增大而减小.对同一种树脂来说,吸附量随着氯代程度的增加而增加,取代氯数相同的时候,吸附量与吸附质的K..成正相关.进一步研究了pH对吸附的影响,在pH大于9时,3种氯酚类物质的吸附量均急剧减少.     

好氧甲烷氧化系统氧氟沙星共代谢效能与微生物特征

氧氟沙星(ofloxacin, OFL)被广泛应用于疾病防治、畜禽养殖等领域,大量使用导致自然环境中存在残留的OFL。甲烷氧化菌在利用甲烷作为生长基质的同时,能通过共代谢的方式实现难降解有机物的生物降解。该研究针对含OFL废水,构建好氧甲烷氧化共代谢系统,开展系统中OFL去除效能和微生物特征研究。结果表明,好氧甲烷氧化系统能够实现OFL的有效降解,OFL的平均去除率可达80.15%。傅里叶红外光谱分析表明,系统能够有效去除氮磷污染物及芳香族化合物。宏基因组学分析表明,在属水平上存在15种甲烷氧化菌,以好氧甲烷氧化菌为主,总丰度为0.30%~0.56%;共检测出157种与甲烷代谢相关的功能基因,起主导作用的功能基因为E2.2.1.1/tktA/tktB、glyA/SHMT和xoxF;KEGG通路层级1共注释出6类代谢途径,KEGG通路层级2共注释出47条代谢途径。药物代谢-其他酶(Drug metabolism - other enzymes)、药物代谢-细胞色素P450(Drug metabolism - cytochrome P450)和细胞色素P450对外源性药物的代谢(Metabolism of xenobiotics by cytochrome P450)能够促进OFL的降解。相关结果可为抗生素及同类化合物的污染防治提供理论依据和技术支撑。     

From land cover change to land function dynamics: a major challenge to improve land characterization

Land cover change has always had a central role in land change science. This central role is largely the result of the possibilities to map and characterize land cover based on observations and remote sensing. This paper argues that more attention should be given to land use and land functions and linkages between these. Consideration of land functions that provide a wide range of goods and services makes more integrated assessments of land change possible. The increasing attention to multifunctional land use is another incentive to develop methods to assess changes in land functions. A number of methods to quantify and map the spatial extent of land use and land functions are discussed and the implications for modeling are identified based on recent model approaches in land change science. The mixed use of land cover, land use and land function in maps and models leads to inconsistencies in land change assessments. Explicit attention to the non-linear relations between land cover, land use and land function is essential to consistently address land change. New methods to map and quantify land function dynamics will enhance our ability to understand and model land system change and adequately inform policies and planning.     

“FPSO+CTV+普通油轮”外输作业模式风险分析

“浮式生产系统(FPSO)+原油转驳船(CTV)+普通油轮”外输作业新模式存在双重的碰撞和泄漏风险,为克服现有研究仅将事故视为单个事件的有序发生或潜在因素的层级叠加等问题,提出一种基于功能共振事故模型(FRAM)的CTV卸油模式风险分析方法。首先,基于FRAM的一般性能条件,识别导致CTV卸油事故发生的人员、技术和组织因素;其次,评价功能性能变化,用以确定关键作业环节和事故演化过程;然后,制定性能波动的防控屏障来预防事故发生。研究结果表明:CTV卸油作业存在25类风险因素和2个关键作业环节,且操作人员的综合素质、CTV的靠泊技术、CTV与FPSO间的沟通效果等是诱导事故发生的关键因素。     

基于STPA-FCM模型的自主航行船舶功能系统分析

为探析自主航行船舶(MASS)功能系统之间的失效机制,提升航行安全,将系统理论过程分析(STPA)方法与模糊认知图(FCM)方法相结合,构建MASS功能系统失效特征分析模型。通过STPA方法对功能系统的控制/反馈关系建模,确定27个控制关系与43个反馈关系,分析潜在的不安全控制行为(UCA)及其产生的关键致因,在此基础上,运用FCM方法构建各功能系统之间的交互关系,并反演出最终稳态下的相对失效概率。结果表明:最为核心的功能模块为电力系统、虚拟船长系统、动力定位系统、避碰系统,其稳定值占比分别为7.66%,7.62%,7.47%,7.14%,应优先确保其可靠性、稳定性和安全性。