长江中下游地区丰水期河、湖水氢氧同位素组成特征

稳定同位素技术在示踪水体的来源、演化及不同水体间相互转化关系、污染源已被广泛地应用.基于2018年7月对长江中下游地区长江干流河水和湖水同位素样品收集,本文分析了长江中下游地区丰水期河水和湖水中δ~(18)O和δ~2H组成特征,在此基础上进一步揭示了其空间上演化特征及其影响因素.结果表明长江干流δ~(18)O和δ~2H值自三峡库区向下游地区呈逐渐增大的变化趋势,这与降水同位素变化密切相关.在三峡库区段与宜昌-城陵矶段河水δ~(18)O和δ~2H值无显著差异,而河水d-excess值波动范围较小.在洞庭湖-江汉和华阳-鄱阳湖湖泊群中湖水δ~(18)O和δ~2H值要贫于太湖-三角洲湖泊群,且太湖-三角洲湖泊群湖水中d-excess值为负值,这主要是太湖-三角洲地区受同位素较为富集的降水和强烈的蒸发作用的影响.在淀山湖和大通湖同位素值最大,洞庭湖和鄱阳湖同位素值偏小,这主要是由于长江与鄱阳湖、洞庭湖直接相通,两湖的水情直接受制于长江影响,水位较高,鄱阳湖和洞庭湖同位素组成受长江水补给影响明显.因此,开展长江中下游河湖水同位素的调查研究,这将对充分认识于了解长江中下游地区大气降水-河水-湖水的相互联系与探讨其水资源合理利用和管理提供科学依据.     

长输管道线路设计优化与环境保护

长输管道建设具有点多、线长、面广的特点,管道沿线会经过各类环境敏感区域,优化管道的线路工程设计可以达到良好的环境保护效果。文章分别从生态、地表水、地下水、大气、噪声、固体废物及环境风险等方面出发,探讨线路工程设计中的环境保护问题,提出相关的保护和防范措施,以达到管道建设和环境保护的和谐发展。     

保温层下管道腐蚀监测系统及应用研究

为预防保温层下管道腐蚀带来的严重问题,必须采取有效措施进行腐蚀在线监测,以了解管道的剩余壁厚情况。在分析现有的腐蚀监测技术不足的前提下,基于γ射线数字扫描检测技术（GSDT）,研发了1套保温层下管道腐蚀在线监测系统,该系统可以实现对保温层下腐蚀管道剩余壁厚在线监测,并通过带保温层管道的检测试验和t-分布分析方法检验腐蚀监测系统的检测精度,最后以某化工企业为例,验证了该系统的有效性。结果表明:腐蚀监测系统可以实现对保温层管道剩余壁厚的监测,保温层和高密度介质不影响管壁厚度的测量结果,且使用所研发的腐蚀监测系统监测到的管道腐蚀速率与现场实际腐蚀速率基本一致。     

Ergonomic interventions for prevention of work-related musculoskeletal disorders in a small manufacturing assembly line

This study involves performing improvements in workstation specification using a three-dimensional human modeling tool and proposing well-balanced work scheduling (WBWS) to prevent work-related musculoskeletal disorders (WMSDs) in a small manufacturing plant. To analyze risk factors of WMSDs, various tasks at 10 different types of workstation were evaluated with detailed motion analysis using a customized checklist. Questionnaires were administered to 27 workers to evaluate symptoms related to WMSDs. Revised workstation specifications were suggested based on anthropometric characteristics of workers using before–after analyses as an engineering control. Additionally, WBWS was proposed as an administrative control to avoid continuous physical stress on specific body parts in repetitive tasks. A software tool for WBWS was developed for convenient and easy application. The results of the study may aid managers in applying ergonomic interventions with time and cost savings, and enhance worker satisfaction and motivation due to improvements in working conditions to prevent WMSDs.     

双线地铁隧道下穿管道安全性对比研究

地铁与燃气管道等高危管道均为线性工程,地铁隧道下穿管道的情况不可避免,一旦因地铁施工导致管道泄漏,后果难以承受,管道沉降值是考量其安全性的关键指标。为对双线盾构地铁隧道下穿管线安全性进行预测,采用修正的Peck公式理论方法进行计算,并与数值模拟结果相对比,研究结果表明:双线盾构地铁隧道下穿管道安全风险可控,修正Peck公式及数值模拟法均能较真实地描绘地表以下任意土层的沉降槽曲线,进而可以比较准确地计算土体竖向沉降,可作为一种用于计算隧道开挖所引起管道竖向位移的方法。     

地铁四线换乘枢纽高峰客流火灾疏散模拟研究

地铁换乘枢纽车站结构复杂、客流密度高,火灾情况下的应急疏散难度大,为研究地铁大型换乘枢纽火灾事故时的客流疏散模式,以四线换乘枢纽CGM站为例,使用building EXODUS软件,分别研究楼梯组、电梯、出入口和闸机组这4类设施无法使用时对乘客疏散时间的影响,以及各场景下乘客的疏散策略。考虑仅站厅乘客参与疏散、1辆列车上的乘客参与疏散、2辆不同线路列车上的乘客参与疏散这3种情况,共设置155个工况。研究结果表明:出入口对于疏散时间的影响较大;楼梯组次之;电梯和闸机组的影响明显小于前2者;同类设施中,由于设施位置及几何特征存在差异,各设施对于疏散时间的影响不同;随着疏散人数的增加,同一设施对于疏散时间的影响随之增加;所有出入口可以使用时,各线路独立疏散时效率较高;发生出入口火灾时,打开线路间换乘通道的防火卷帘门可降低所需疏散时间。     

林业碳汇项目基准线和监测方法学及应用分析——以贵州省贞丰县林业碳汇项目为例

气候变化给全球社会经济发展带来了重大影响,林业碳汇在适应和减缓气候变化、促进可持续发展三方面的重要作用日益被世界各国所认可。林业碳汇项目实施的难点在于准确掌握林业碳汇项目设计的规则、标准体系,重点在于基准线判别、碳汇计量、监测的方法学和工具。本文系统介绍了国际清洁发展机制造林再造林(CDM A/R)项目方法学和国内碳汇造林项目方法学、标准体系等最新成果,并以贵州省贞丰县林业碳汇项目为例,分析了基准线和监测方法学在林业碳汇项目开发设计中的实际应用。     

高铁建设项目安全风险分析及对策研究——以西宝客运专线Ⅱ标为例

本文针对国内高铁客运专线建设项目,对如何识别风险、分析风险、控制风险和应对风险进行了初步研究,并以西宝高铁建设项目为例,通过风险分析评价了该客运专线建设项目的风险因素,确定了各种因素对建设项目实施的影响程度大小,并依据风险分析的结果提出了加强该客运专线建设施工风险管理的主要对策,以实现将风险有效地控制在决策者预定的范围之内。该研究可为高铁客运专线建设项目的施工风险管理工作提供理论及实践的借鉴。     

How to evaluate models: Observed vs. predicted or predicted vs. observed?

A common and simple approach to evaluate models is to regress predicted vs. observed values (or vice versa) and compare slope and intercept parameters against the 1:1 line. However, based on a review of the literature it seems to be no consensus on which variable (predicted or observed) should be placed in each axis. Although some researchers think that it is identical, probably because r² is the same for both regressions, the intercept and the slope of each regression differ and, in turn, may change the result of the model evaluation. We present mathematical evidence showing that the regression of predicted (in the y-axis) vs. observed data (in the x-axis) (PO) to evaluate models is incorrect and should lead to an erroneous estimate of the slope and intercept. In other words, a spurious effect is added to the regression parameters when regressing PO values and comparing them against the 1:1 line. Observed (in the y-axis) vs. predicted (in the x-axis) (OP) regressions should be used instead. We also show in an example from the literature that both approaches produce significantly different results that may change the conclusions of the model evaluation.     

Meta‐Analysis of the Effectiveness of Marked Wire in Reducing Avian Collisions with Power Lines

Abstract: Collisions of birds with power transmission and distribution lines have been documented for many species, and cause millions of casualties worldwide. Attempts to reduce mortality from such collisions include placing bird flight diverters (i.e., wire markers in the form of, e.g., spirals, swivels, plates, or spheres) on static and some electrified wires to increase their visibility. Although studies of the effectiveness of such devices have yielded contradictory results, the implementation of flight diverters is increasing rapidly. We reviewed the results of studies in which transmission or distribution wires were marked and conducted a meta‐analysis to examine the effectiveness of flight diverters in reducing bird mortality. We included in our meta‐analysis all studies in which researchers searched for carcasses of birds killed by a collision with wires. In those studies that also included data on flight frequency, we examined 8 covariates of effectiveness: source of data, study design, alternate design (if marked and unmarked spans were alternated in the same line), periodicity of searches for carcasses, width of the search transect, and number of species, lines, and stretches of wire searched. The presence of flight diverters was associated with a decrease in bird collisions. At unmarked lines, there were 0.21 deaths/1000 birds (n =339,830) that flew among lines or over lines. At marked lines, the mortality rate was 78% lower (n =1,060,746). Only the number of species studied had a significant influence on effect size; this was larger in studies that addressed more species. When comparing mortality at marked and unmarked lines, we recommend use of the same time intervals and habitats and standardizing the periodicity of carcass searches.