烧结机尾“电改袋”除尘器数值模拟

针对现有"电改袋"除尘器不易实现在运行中更换滤袋且内部气流分布不均匀等问题,结合某烧结厂190 m2"电改袋"工程实例,提出一种可以在运行中更换滤袋的分室式"电改袋"除尘器结构,并利用CFX软件模拟其流场。结果表明,烟气由进气烟道进入袋室时速度大小和方向均发生突变,大颗粒粉尘受惯性力和重力作用易被中间灰斗捕集,有效减缓粉尘对滤袋的磨损;滤袋底部附近区域和两侧灰斗内的烟气速度分别小于5 m/s和6 m/s,可有效防止滤袋间的碰撞磨损和灰斗二次扬尘;各袋室的烟气流量分布比较均匀,标准差为0.152。     

The role of self-regulation in the context of driver distraction: A simulator study

Objective: There is considerable evidence for the negative effects of driver distraction on road safety. In many experimental studies, drivers have been primarily viewed as passive receivers of distraction. Thus, there is a lack of research on the mediating role of their self-regulatory behavior. The aim of the current study was to compare drivers' performance when engaged in a system-paced secondary task with a self-paced version of this task and how both differed from baseline driving performance without distraction.

Methods: Thirty-nine participants drove in a simulator while performing a secondary visual–manual task. One group of drivers had to work on this task in predefined situations under time pressure, whereas the other group was free to decide when to work on the secondary task (self-regulation group). Drivers' performance (e.g., lateral and longitudinal control, brake reaction times) was also compared with a baseline condition without any secondary task.

Results: For the system-paced secondary task, distraction was associated with high decrements in driving performance (especially in keeping the lateral position). No effects were found for the number of collisions, probably because of the lower driving speeds while distracted (compensatory behavior). For the self-regulation group, only small impairments in driving performance were found. Drivers engaged less in the secondary task during foreseeable demanding or critical driving situations.

Conclusions: Overall, drivers in the self-regulation group were able to anticipate the demands of different traffic situations and to adapt their engagement in the secondary task, so that only small impairments in driving performance occurred. Because in real traffic drivers are mostly free to decide when to engage in secondary tasks, it can be concluded that self-regulation should be considered in driver distraction research to ensure ecological validity.     

氨排放对华北典型地区冬季二次无机盐生成的影响

为研究氨排放对冬季PM_(2.5)中二次无机盐的影响,设置不同排放情景,应用CMAQ模式对华北地区典型城市——保定冬季无机盐进行了模拟研究。结果表明:将氨气在模式中排放置零的情景下,无机盐质量浓度降低了67.08%;氨排放削减与二次无机盐生成呈非线性关系,大气呈"氨限制"状态;氨排放削减能够有效抑制二次无机盐的生成,当削减幅度为50%时无机盐总体降幅达29.89%,其中硝酸盐、铵盐和硫酸盐降幅分别为53.78%、27.87%和5.64%;氨排放对重污染时段二次无机盐的生成贡献较高,当氨削减幅度为50%时无机盐总体降低40.58%;在当前大气环境下,氨排放削减是保定市冬季控制二次无机盐污染的重要途径。     

驾驶人视觉注意力需求与驾驶行为特性的关系

采用驾驶模拟系统平台,以不同车道类型及不同交通流状态(自由流/稳定流/不稳定流/强制流)为虚拟试验场,应用心理试验设计方法,测试得到21名被试在不同交通流状态下的视觉注意力需求及驾驶行为。对5种车道类型及4种交通流状态下被试驾驶时的视觉注意力需求特性和驾驶行为特性数据进行分析,得到不同车道不同交通流状态下的视觉注意力需求变化情况。利用多元回归方法分析了不同交通流状态下驾驶人视觉注意力需求与驾驶行为之间的关系,并构建了基于驾驶行为特性的驾驶人视觉注意力需求预测模型。结果表明,驾驶人视觉注意力需求与制动次数、油门踏板位移和车辆轨迹偏差之间存在相关关系。     

Degradation behavior of 17αup-ethinylestradiol by ozonation in the synthetic secondary effluent

Endocrine disrupting chemicals (EDCs) in the secondary effluent discharged from wastewater treatment plants (WWTPs) are of great concern in the process of water reuse. Ozonation has been reported as a powerful oxidation technology to eliminate micropollutants in water treatment. Due to the complexity of the wastewater matrix, orthogonal experiments and single factor experiments were conducted to study the influence of operational parameters on the degradation of 17αup-ethinylestradiol (EE2) in the synthetic secondary effluent. The results of the orthogonal experiments indicated that the initial ozone and natural organic matter (NOM) concentration significantly affected EE2 degradation efficiency, which was further validated by the single factor confirmation experiments. EE2 was shown to be effectively degraded by ozonation in the conditions of low pH (6), NOM (10 mg/L), carbonate (50 mg/L), but high suspended solid (20 mg/L) and initial ozone concentration (9 mg/L). The study firstly revealed that the lower pH resulted in higher degradation of EE2 in the synthetic secondary effluent, which differed from EDCs ozonation behavior in pure water. EE2 degradation by ozone molecule instead of hydroxyl radical was proposed to play a key role in the degradation of EDCs by ozonation in the secondary effluent. The ratio between O₃ and TOC was identified as an appropriate index to assess the degradation of EE2 by ozonation in the synthetic secondary effluent.     

Uptake of isoprene, methacrylic acid and methyl methacrylate into aqueous solutions of sulfuric acid and hydrogen peroxide

Multiphase acid-catalyzed oxidation by hydrogen peroxide has been suggested to be a potential route to secondary organic aerosol formation from isoprene and its gas-phase oxidation products, but the lack of kinetics data significantly limited the evaluation of this process in the atmosphere. Here we report the first measurement of the uptake of isoprene, methacrylic acid and methyl methacrylate into aqueous solutions of sulfuric acid and hydrogen peroxide. Isoprene cannot readily partition into the solution because of its high volatility and low solubility, which hinders its further liquid-phase oxidation. Both methacrylic acid and methyl methacrylate can enter the solutions and be oxidized by hydrogen peroxide, and steady-state uptake was observed with the acidity of solution above 30 wt.% and 70 wt.%, respectively. The steady-state uptake coefficient of methacrylic acid is much larger than that of methyl methacrylate for a solution with same acidity. These observations can be explained by the different reactivity of these two compounds caused by the different electron-withdrawing conjugation between carboxyl and ester groups. The atmospheric lifetimes were estimated based on the calculated steady-state uptake coefficients. These results demonstrate that the multiphase acid-catalyzed oxidation of methacrylic acid plays a role in secondary organic aerosol formation, but for isoprene and methyl methacrylate, this process is not important in the troposphere.     

污水生物处理系统后置化学除磷影响因素分析

通过对污水处理厂二沉池出水的后置化学除磷试验研究,分析了药剂种类、二沉池出水磷浓度和浊度对化学除磷效果的影响。实验结果表明,聚合硫酸铁的化学除磷效果略优于聚合氯化铝。随着进水磷浓度的升高,投加Fe/去除P的摩尔比会明显降低,这可能与化学除磷沉淀物的吸附和络合作用有关。二沉池出水浊度对后置化学除磷具有竞争性影响,较高的出水浊度将增大药剂消耗量。因此,污水处理厂采用化学加药后除磷工艺时,应根据二沉池出水总磷和浊度范围进行最佳投药量试验,并采取自动控制措施根据出水水质调节加药量,确保出水总磷稳定达标。     

改进BCR提取法对山东荣成天鹅湖金属环境赋存研究

采用改进的BCR提取法,分析2009年11月采集的山东荣成天鹅湖表层沉积物中Cu、Pb、Zn、Cr的环境赋存(酸可溶态、可还原态、可氧化态及残渣态);以污染系数法(CF)和次生相原生相分布比值法(RSP)对金属外源输入影响以及潜在的生物危害进行了分析。结果表明:Cu以可还原态和残渣态为主,各站位的潜在生物危害有差异;Pb的醋酸可提取态与可还原态达60.8%,生物可利用性强,具有较高的潜在生态危害;Zn和Cr主要以稳定的残渣态(分别为64.3%和57.1%)形式存在,同时受外源输入的影响也较轻微(CF<1),因而不具有环境危害。     

黄河入海口潮间带大型底栖动物群落组成及次级生产力

为了解黄河入海口潮间带大型底栖生物现状,于2008年和2009年黄河枯水期的5月和丰水期的8月分别对黄河入海口5条潮间带断面大型底栖动物进行了采样调查。结果表明,采集到大型底栖动物65种,其中软体动物26种、甲壳动物22种、多毛类12种、腔肠动物2种、腕足动物、棘皮动物和鱼类各1种。软体动物和甲壳动物是构成潮间带底栖动物的主要类群。黄河入海口潮间带大型底栖动物平均栖息密度为(929.60±356.53)/m2,平均生物量(湿重)为(169.92±7.31)g/m2。在栖息密度组成中,软体动物占绝对优势,其次甲壳动物和多毛类,其他类群较低。Shannon-Weiner多样性指数为1.44±0.44,Margalef物种丰富度指数1.57±0.15,Pielou均匀度指数0.42±0.11。年平均去灰干重(13.96±0.61)g(AFDW)/m2,年次级生产力(11.26±0.62)g(AFDW)/(m2.a),P/B值平均(0.89±0.11)/a,表明黄河入海口潮间带个体较大、生活史较长的大型底栖动物种类所占比例较高。     

某单井站场管道积液及腐蚀特性研究*

为应对湿天然气管道存在的明显积液,导致管材腐蚀,目前经验性的检测点选择方式导致检测成本和工作量过大问题。基于某单井站场工况条件和现场壁厚检测数据,针对站场主管线,采用Fluent软件建模分析管线内液相分布规律。结果表明:含液率大小随原料气含水量、流量、压力的变化而呈正相关变化,运用Correl函数对现场壁厚检测数据和模拟结果进行对比验证,发现两者的相关度达到0.61以上,这为现场合理选择腐蚀检测点提供依据,降低了现场检测工作量和检测成本。