地铁浅埋岛式站台列车火灾烟气蔓延的数值模拟研究

地铁车站及地铁列车为人流密集的公众聚集场所,一旦发生火灾事故,伤亡损失往往非常惨重。地铁作为现代化的城市轨道交通工具,承担着越来越重要的大客流运输任务。因此,深入开展地铁火灾安全的研究有助于地铁安全管理工作。针对地铁浅埋岛式站台列车火灾情况,利用数值模拟-场模拟方法,研究浅埋岛式站点内烟气横向流动和不同站层间的烟气纵向蔓延规律。分析烟气在隧道、站台及站厅内蔓延时烟气温度、有毒气体浓度、可见度等特征参数的分布情况;探讨了火灾时浅埋岛式站点内有效的气流组织形式,隧道排烟系统的运行模式;该研究结论有助于同类型的地铁车站的设计和运营管理。     

烟气输运和水喷淋相互作用的大涡模拟研究

本文应用大涡模拟方法，并结合Smagorinsky亚格子尺度模型，数值研究了烟气输运和水喷淋的相互作用问题。为了有效地模拟烟气输运过程，文中采用低马赫数近似下的三维可压缩Navier-Stokes方程和组分方程进行求解，并采用有限差分法数值计算了滤波后的控制方程。对于燃烧过程扣所产生的热释放，采用Lagrangian粒子携带热量的近似方法来模拟，这些运动粒子进一步用来标识烟气的输运过程，同时还近似模拟了水喷淋和热气流的相互作用过程。文中数值计算了燃烧火源所形成的热气流和烟气输运过程，以及与水喷淋的相互作用，并探讨了喷水装置的喷水量、喷射角和水颗粒直径对流动特性的影响。     

重庆祺龙村垃圾填埋场渗滤液污染特性

针对重庆祺龙村垃圾填埋场特有的水文地质条件建立相应的数学模型,确定模型的初始条件和边界条件,并进行区域离散.采用已建立的数学模型模拟有监测资料时段的渗滤液ρ(COD_Cr)和地下水水位,并把模拟值与实测值进行对比,校正模型;当模拟值与实测值较接近时,得到比较符合客观实际的数学模型.最后采用已验证的符合客观实际的数学模型,定量模拟和分析了垃圾填埋场场内、外,南、北边,以及两侧渗滤液ρ(COD_Cr)的变化,从而得到祺龙村垃圾填埋场渗滤液的污染特性.结果表明:填埋场内渗滤液污染最大,其次是南边部位,之后依次是第四纪松散堆积层,砂岩、泥岩分布区;断层是渗滤液污染物运移的通道,在其他条件相同的情况下,断层通过处及其附近污染程度大.      

基于典型案例的电梯轿厢意外移动保护装置的设置及检验探讨

检规TSG T7001-2009第2号修改单新增了对轿厢意外移动保护装置的检验要求,其中对检测子系统的检验理解存在着一定的争议.本文从轿厢意外移动保护装置的设置和组成出发,结合相关检验案例和标准要求探讨了对轿厢意外移动保护装置检验要求的理解,最后对轿厢意外移动保护装置的检验方法进行了分析,并提出了检验方面的建议.     

塔机驾驶员的持续性视觉注意负荷研究

为提高塔机作业安全工效,基于视觉心理学、认知心理学理论,利用眼动追踪技术记录驾驶员视觉行为数据,分析和评估塔机驾驶员视觉转移过程的表征参数,结果表明:起重作业过程中驾驶员注视时间长,视知觉资源主要集中于起吊物,保持持续性注意状态,以维持高效起重作业,心理负荷较大;起重作业不同子过程注视时间与瞳孔直径差异较大,在空中平移过程中注意力较为分散,瞳孔直径较小,心理负荷较小。据此,提出了塔机起重作业的人因工效改善方向,为起重作业安全实施提供决策支持。     

电梯轿厢意外移动保护装置检验的研究

为厘清制造单位和检验机构对轿厢意外移动保护装置的认识,达到降低生产成本,提高检验质量的目的,本文从轿厢意外移动保护装置的组成和各子系统的作用,结合《电梯制造与安装安全规范》国家标准第1号修改单(GB 7588-2003/XG1-2015)对轿厢意外移动保护装置的要求,按轿厢意外移动保护装置子系统的组合分成3类电梯,并根据电梯类型提出合理的检验方法,研究结果表明:使用非驱动主机制动器做制停子系统的电梯,需要检验与检测子系统和制停子系统相关的项目;使用驱动主机制动器做制停子系统的电梯,需要检验与检测子系统、制停子系统和自监测子系统相关的项目;不需要检测轿厢意外移动的电梯,需要检验与制停子系统和自监测子系统相关的项目.     

Focusing Ecological Research for Conservation

Ecologists are increasingly actively involved in conservation. We identify five key topics from a broad sweep of ecology that merit research attention to meet conservation needs. We examine questions from landscape ecology, behavioral ecology, ecosystem dynamics, community ecology, and nutrient cycling related to key topics. Based on literature review and publication trend assessment, consultation with colleagues, and roundtable discussions at the 24th International Congress for Conservation Biology, focused research on the following topics could benefit conservation while advancing ecological understanding: 1. Carbon sequestration, requiring increased linkages to biodiversity conservation; 2. Ecological invasiveness, challenging our ability to find solutions to ecological aliens; 3. Individual variation, having applications in the conservation of rare species; 4. Movement of organisms, integrating ecological processes across landscapes and scales and addressing habitat fragmentation; and 5. Trophic-level interactions, driving ecological dynamics at the ecosystem-level. Addressing these will require cross-disciplinary research under the overarching framework of conservation ecology.     

Pseudomonas fluorescens Dynamics in the Soil Surface to Subsurface Transect

Microbial displacement in the soil is an important process for bioremediation and dispersal of wastewater pathogens. We evaluated cell movement in surface and subsurface red-yellow podzolic soil driven by advection and microbial motility and also survival of a microbial population at high pressure as is prevalent in deep soil layers. Pseudomonas fluorescens Br 12, resistant to rifampycin and kanamycin, was used as a model organism traceable in non-sterile soil. Our results showed that more than 40% of the P. fluorescens population survived under high pressure, and that microbial motility was not a major factor for its displacement in the soil. Cells were adsorbed in similar amounts to surface and subsurface soils, but more viable cells were present in the leachate of surface than in subsurface soils. The nature of this unexpected cell binding to the subsurface soil was studied by EPR, Mossbauer, NMR, and infrared techniques, suggesting iron had a weak interaction with microbes in soil. P. fluorescens movement in soil resulted mainly from convection forces rather than microbial motility. The transport of this bacterium along the transept toward groundwater encountered restricted viability, although it survived under high pressure conditions simulating those in deep soil layers.     

The influence of neighborhood traffic density on the respiratory health of elementary schoolchildren

Background

Several studies have found that living near major roadways is associated with an increase in respiratory illness but few studies have measured the volume and type of traffic.

Objective

We investigated the relation between traffic volume and respiratory health of 2328 children 9 to 11 years old in the city of Windsor, Canada.

Methods

We identified the roadways within a 200 meter radius of the child's neighborhood using the latitude and longitude of the residential postal code. Traffic exposure was defined as the sum of the annual volume of vehicles on all of these roadways. Volume was calculated using sensors to detect passing vehicles (simple traffic counts), and by counts and direction of traffic at intersections (turning movement counts). Ventilatory lung function was measured by spirometry and airway inflammation by exhaled nitric oxide (eNO).

Results

The odds ratio between an interquartile increase in truck turning movement counts and chest congestion was 1.20 (1.06-1.35). The percentage of predicted FVC declined 0.68%, (95% CI 1.32, 0.03) for an interquartile increase in simple traffic counts (33,787 vehicles daily). Among those with self-reported asthma, effect sizes were larger. Percentage predicted FEV₁ declined 1.84% (95% CI 0.07, 3.61) associated with an interquartile range increase in turning movement counts. No statistically significant change was detected between traffic measures and exhaled nitric oxide.

Conclusions

Our findings provide further support for the hypothesis that neighborhood exposure to traffic-related air pollution increases respiratory symptoms and reduces ventilatory function in children, especially those with self-reported asthma.     

Reduction of the movement and persistence of pesticides in soil through common agronomic practices

Laboratory and field studies were conducted in order to determine the leaching potential of eight pesticides commonly used during pepper cultivation by use of disturbed soil columns and field lysimeters, respectively. Two soils with different organic matter content (soils A and B) were used. Additionally, soil B was amended with compost (sheep manure). The tested compounds were cypermethrin, chlorpyrifos-methyl, bifenthrin, chlorpyrifos, cyfluthrin, endosulfan, malathion and tolclofos-methyl. In soil B (lower organic matter content), only endosulfan sulphate, malathion and tolclofos-methyl were found in leachates. For the soil A (higher organic matter content) and amended soil B, pesticide residues were not found in the leachates. In addition, this paper reports on the use of common agronomic practices (solarization and biosolarization) to enhance degradation of these pesticides from polluted soil A. The results showed that both solarization and biosolarization enhanced the degradation rates of endosulfan, bifenthrin and tolclofos-methyl compared with the control. Most of the studied pesticides showed similar behavior under solarization and biosolarization conditions. However, chlorpyrifos was degraded to a greater extent in the solarization than in biosolarization treatment. The results obtained point to the interest in the use of organic amendment in reducing the pollution of groundwater by pesticide drainage and in the use of solarization and biosolarization in reducing the persistence of pesticides in soil.