输水隧道的减震措施研究

隔震技术是近几十年发展起来的新技术,对地面结构减震效果显著。本文运用Newmark隐式时间积分有限元法并采用粘-弹性人工边界,分析了在输水隧道施工中设置减震层和注浆加固一定范围内围岩这2种方法的减震效果、适用条件及其减震机理。计算结果表明:减震层或加固层的设置均使隧道衬砌应力减小,起到保护隧道衬砌的作用;在较大的范围内注浆加固围岩的办法,对软土中的输水隧道的减震更加有效,它能充分发挥围岩的承载能力;而在围岩与衬砌间设置减震层的办法,对稳定性极好的坚硬围岩中的输水隧道的减震效果更加有效。计算结果可为地震区的输水隧道抗震设计提供依据。     

溴虫腈在土壤的残留动态

通过超临界流体萃取技术结合气相色谱法,研究了土壤中溴虫腈的残留降解动态。正交试验L9(33)结果表明,在流量25~27 m3.h-1,夹带剂甲醇1 mL.g-1样品时,最佳萃取条件为压力25 MPa,温度39℃,时间30 min。超临界萃取试验结果表明,主要影响因素对溴虫腈回收率的影响高低程度依次为萃取温度,萃取时间,萃取压力。验证试验表明,在上述最佳萃取条件下,溴虫腈添加量为10μg、100μg、200μg时,回收率分别是105.00%、80.33%、102.33%,变异系数分别是7.32%、4.58%、4.95%。降解动态试验表明溴虫腈在土壤中的消解动态方程为Ct=0.097 2e-0.4501 t,R2=0.973 7,t1/2=2.4 d。溴虫腈10%悬浮剂(商品名除尽)在推荐剂量50 mL.(667 m2)-1或100 mL.(667 m2-)1使用2~3次,3~7 d后在土壤中残留量为6.44~23.58μg.kg-1,消解速度较快,属于易降解农药,可合理使用于无公害蔬菜生产。     

麻疯树对铅胁迫的生理耐性研究

通过盆栽试验研究土壤中不同浓度（0、200、400、800、1 600和3 200 mg.kg-1）Pb胁迫对麻疯树生长、Pb吸收及相关生理指标的影响。结果表明,当土壤w（Pb）≥800 mg.kg-1时,麻疯树生长受到明显抑制;麻疯树植株不同部位Pb含量随土壤Pb浓度的升高而增加,且各部位Pb含量从高到低依次为根、叶和茎;当土壤w（Pb）≥800mg.kg-1时,麻疯树叶中超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性,以及可溶性糖、脯氨酸和酸溶性巯基（SH）含量均显著提高,而谷胱甘肽（GSH）含量仅在土壤w（Pb）为3 200 mg.kg-1时才显著增加;可溶性蛋白质含量随Pb浓度的增加呈倒＂W＂型变化,当土壤w（Pb）为400 mg.kg-1时,其含量最大;上述生理指标的变化可缓解重金属Pb对麻疯树的毒害。主成分分析结果表明Pb胁迫处理的聚类结果与各处理麻疯树生物量及生理指标的变化规律相吻合,POD活性和可溶性糖含量对缓解重金属Pb毒害的贡献较大。可见,麻疯树在Pb污染土壤修复中具有一定的应用前景。     

AFB的活性污泥中发酵细菌的分离及其初步鉴定

从处理啤酒废水的厌氧流化床的活性污泥中分离纯化到了发酵细菌,并对其培养条件进行了研究,实验表明,该发酵细菌最佳培养温度为37～42℃,最佳培养时间为28 d,同时对其进行了生理生化和形态鉴定。将该发酵细菌反加到AFB反应器中,能有效降低反应器的启动时间,能提高反应器处理啤酒废水的处理效率约8%。     

Optimization of dilution ventilation layout design in confined environments using Computational Fluid Dynamics (CFD)

Dilution ventilation systems have been widely used to control the airborne toxic and explosive material in confined spaces. Layout design of dilution ventilation is critical to industrial hygiene control and ventilation efficiency. A properly designed dilution ventilation system can significantly improve the safety of confined workshops and maintain a comfortable work condition. In this work, Computational Fluid Dynamics (CFD) has been used to analyze the performance of dilution ventilation system in the confined workshop environment. Seven different ventilation layouts are proposed to evaluate ventilation performance of different installation layouts. Carbon monoxide (CO), which has the similar density as air, is selected as the sample contaminant to conduct steady-state CFD simulations. The simulation results of different layouts are examined and compared to get the optimal layout design for the best contaminant control. Results have shown that the layout with two opposite inlets has the highest ventilation efficiency among seven proposed layouts. This work can serve as a reference to increase dilution ventilation efficiency and minimize the energy cost in general confined areas.     

Strengthening conservation science as a crisis discipline by addressing challenges of precaution,privilege, and individualism

Conservation science deals with crises and supports policy interventions devised to mitigate highly uncertain threats that pose irreversible harm. When conventional policy tools, such as quantitative risk assessments, are insufficient, the precautionary principle provides a practical framework and range of robust heuristics. Yet, precaution is often resisted in many policy arenas, especially those involving powerful self-interests, and this resistance is compounded by structures of privilege and competitive individualism in science. We describe key drivers and effects of such resistance in conservation science. These include a loss of rigor under uncertainty, an erosion of crisis response capabilities, and a further reinforcement of privileged interests in conservation politics. We recommend open acknowledgement of the pressures exerted by power inside science; greater recognition for the value of the precautionary principle under uncertainty; deliberate measures to resist competitive individualism; support for blind review, open science, and data sharing; and a shift from hierarchical multidisciplinarity toward more egalitarian transdisciplinarity to accelerate advances in conservation science. Article impact statement: Precautionary principle, privilege structures among disciplines, and culture of individualism link to effective conservation policy making.     

提高电除尘器过滤效率的软稳电除尘技术及其应用

主要介绍了在国家外排粉尘浓度标准日益严格，普通电除尘器很难达标的背景下，提高电除尘器过滤效率的一种新技术软稳电除尘技术的原理和应用。     

Societal risk acceptance criteria for gas distribution pipelines based on incident data from the United States

A significant number of pipeline operators use pipeline integrity management (PIM) to improve pipeline safety and reliability. Risk assessment is a critical step in PIM, because it determines the necessity of conducting the following steps in PIM for certain pipelines. Risk acceptance criteria are required in the process of risk assessment. Individual risk and societal risk are most frequently adopted as the two indicators of the risk acceptance criteria. To the best of the authors’ knowledge, quantitative societal risk acceptance criteria, especially for gas distribution pipelines, do not exit. The aim of this paper is to establish the societal risk acceptance criteria for gas distribution pipelines. Hence, FN curves were established using historical incident data from 2002 to 2017 provided by the U.S. Department of Transportation (DOT). Linear regression and the ALARP principle are used in evaluating the limits of the negligible line and intolerable line to obtain a graphical societal risk acceptance criterion for gas distribution pipelines. A line having a slope of −1.224, and an anchor point of (1, 8.413 × 10⁻⁷) is proposed as the negligible line. Further, the intolerable line has a slope of −1.224, and an anchor point of (1, 2.524 × 10⁻⁶). Both the negligible risk and the intolerable risk for the gas distribution pipeline are lower than the current societal risk acceptance criteria for hazardous installations. The reasons for these relatively lower risk acceptance criteria are discussed.     

电子垃圾拆解地周边土壤中二(口恶)英和二(口恶)英类多氯联苯的浓度水平

采集了电子垃圾拆解地周边125个点位的151个土壤样品,分析了土壤中4~8氯代二噁英和二噁英类多氯联苯的浓度.表层土壤样品中总二噁英的浓度范围为280~7 010 pg·g-1,平均浓度为1 380 pg·g-1.中层和深层土壤样品中总二噁英的平均浓度分别为表土的63%和38%.表土样品中二噁英毒性当量浓度(以I-TEQ计)范围为1.4~94.8 pg·g-1.根据德国关于毒性当量浓度的指导方针,125个土壤样品中只有19个(15%)可以被认为对人体健康无害,其余85%的土壤需要调查二噁英的来源.如果考虑多氯联苯对毒性当量的贡献,则有98%的土壤需要调查二噁英的来源.主因子分析被用来调查这一地区二噁英的排放源.通过对土壤中二噁英的同系物分布进行分析,发现拆解活动是这一地区热过程二噁英的主要排放源,也是这一地区土壤中二噁英的主要来源.     

基于LDI的土地利用类型与湿地水质的相关性:以苏州太湖三山岛国家湿地公园为例

以苏州太湖三山岛国家湿地公园为例,探索不同时空条件下土地利用类型整体与水质之间的相关关系.使用主成分分析计算出每个采样点的水质综合指数,基于GIS空间分析技术计算表征土地利用类型综合效应的景观开发强度指数(landscape development intensity,LDI),运用Pearson相关分析探讨水质与土地利用类型之间的整体相关性.结果表明,水质随着湿地公园空间分布不同而有较大的差异,研究区西部水质较好,东部水质较差;建设用地与水质综合指数存在明显的正相关,自然水体则与水质综合指数呈显著的负相关;缓冲区半径为100、150、200、250、300、350、400、450和500 m的LDI综合指数与水质综合指数的Pearson相关系数分别为0.641、0.678、0.691、0.685、0.691、0.695、0.680、0.653和0.649(P0.01),它们之间存在显著而稳定的相关性,可以体现出多种土地利用类型对湿地水质的整体影响,部分克服了单项土地利用类型表达不完整、难以解释水质变化的不足.