杭州城区PM2.5和PM10污染特征及其影响因子分析

利用2013年12月—2014年11月杭州城区空气质量监测站PM_(2.5)、PM_(10)浓度值结合气象、道路、人口数据以及站点周边绿地信息分析PM_(2.5)、PM_(10)浓度时空特征及其影响因子。结果表明,杭州城区各监测站PM_(2.5)和PM_(10)晴天日浓度变化趋势基本一致,PM_(2.5)比PM_(10)污染严重;晴天日PM_(2.5)、PM_(10)浓度值与对应的温度(-0.463,-0.281)、风速(-0.305,-0.332)呈负相关,与湿度(0.257,0.239)呈正相关;晴天有风时,杭州市区PM_(2.5)、PM_(10)污染北部重于南部,东部重于西部,浓度极高值集中在风速小于5 m/s时段,且风速越小浓度值越高;温度为12℃左右,湿度在60%~80%时,颗粒物污染最严重;交通高峰时各监测站PM_(2.5)、PM_(10)污染程度存在明显差异。相关性分析表明,PM_(2.5)、PM_(10)污染程度与道路密度成正比,与缓冲区内绿地覆盖面积成反比。PM_(2.5)污染程度与人口密度成正比,PM_(10)污染与人口密度成反比。     

烟花爆竹禁燃对春节期间东北地区空气质量影响评估

利用2015—2017年春节期间东北地区主要大气污染物(PM_(10)、PM_(2.5)、SO_2、NO_2、CO和O3)质量浓度监测资料及相应气象因子(温度、湿度、风速和气压)观测资料,分析了春节期间烟花爆竹禁燃对东北地区空气质量的影响。结果表明:随着东北地区主要城市禁燃力度的增强,空气质量逐年提升,PM_(2.5)和SO_2浓度逐年大幅度下降。禁燃可明显降低城区PM_(2.5)浓度,而由于春节期间污染源整体减少,城区和城郊监测点PM_(2.5)浓度值差异减小。烟花爆竹对PM_(10)和PM_(2.5)浓度影响高于对气体污染物SO_2、NO_2和CO的影响。此外,气象条件对东北地区春节期间禁燃改善空气质量的效果也有明显影响。因此,结合春节期间的气象条件,在东北地区实施禁燃政策动态调整非常必要。     

Ground influence on high-pressure methane jets: Practical tools for risk assessment

High-pressure gaseous methane release is a relevant safety-related problem mainly in the Oil and Gas industry. As well documented, the reason for these safety concerns is connected with the severe consequences of the domino effect subsequent to the possible ignition. In risk assessment activities, estimation of the damage area is of primary importance in order to draw up proper safety guidelines. To do this, loss prevention specialists use quick and well-established numerical tools (i.e., integral models) in their daily activities. However, the presence of an obstacle in the flow field of the jet (e.g., the ground) is a more probable situation to deal with. It is known that integral models fail in this kind of scenario, leading to unreliable predictions. Hence, the present work investigates how an industrial ground surface influences the LFL cloud size of a horizontal high-pressure methane jet. An innovative quick procedure is proposed allowing to determine the height below which the ground begins to influence the LFL cloud size and the extent of such influence. Therefore, this procedure allows practitioners to establish when integral models can be used and when not to use them, and also provides a simple and reliable alternative to their use. These analytical instruments are derived from an extensive computational fluid dynamics analysis performed with Ansys Fluent 19.0.     

Young drivers' determinants of driving under the influence of cannabis: Findings from the Youth Cannabis and Driving Survey (YouCanDS)

Introduction: Driving under the influence of cannabis (DUIC) is proven to increase the risk of collisions and is most common among young drivers (ages 16 to 24). However, little is known about the specific determinants of DUIC behavior among youth, which limits the capacity to develop evidence-based prevention and intervention efforts. This study developed and evaluated a youth DUIC questionnaire, which was used to establish the DUIC determinants of young drivers. Method: The questionnaire was based on the theoretical framework of general deterrence and general prevention. Data obtained included: demographics, past cannabis use and DUIC experiences, DUIC intention, experiences riding as a passenger with someone DUIC, knowledge and credibility of the law, attitudes towards DUIC, and social controls. The resulting questionnaire was validated for a sample of 426 young drivers in the province of Ontario, Canada. An ordinal regression was conducted to examine the relationships between questionnaire items and DUIC intention. Results: The questionnaire displayed good construct validity and internal consistency across four out of five domains (KMO and Cronbach α values ≥ 0.70). Of the 426 respondents (52.6% female), 356 (83.6%) reported previous cannabis use, with 296 (69.5%) doing so in the past year, and 142 (33.3%) reporting DUIC. Furthermore, 179 (42%) study participants indicated at least a slight chance of DUIC in the next year. The regression analysis identified six variables predictive of DUIC intention: past DUIC incidence, perceived percent of those convicted that receive the penalty, moral awareness, perceived dangerousness, minor accident risk, and vicarious punishment avoidance. Conclusions: Preventive efforts should emphasize these determinants when designing targeted strategies and interventions. Practical Applications: These efforts should focus on educating the dangers and risk of a vehicle collision, that law enforcement has the capacity to apprehend and appropriately punish individuals DUIC, and that DUIC is wrong and socially unacceptable.     

2008～2017年北京市PM2.5周期性变化特征与影响机制

利用Morlet小波方法分析北京市2008~2017年PM_2.5资料,结果表明,北京市PM_2.5浓度存在显著的日变化、周变化、以及季节和年变化周期性特征,并且秋冬季的周期性特征显著高于春夏季.结合气象资料,包括水平风速、大气边界层高度、以及大气稳定度指数等,分析PM_2.5不同周期性变化对应的主要影响机制表明：大气边界层过程是PM_2.5日变化的主要影响机制,导致PM_2.5浓度白天低、夜间高.秋冬季PM_2.5日变化幅度高于春夏季;天气过程是PM_2.5周变化的主要机制,PM_2.5浓度与天气变化过程带来的风速变化和边界层高度呈强反相关关系;PM_2.5的季节变化与大气扩散能力的季节变化密切相关,秋冬季减弱的大气扩散能力加速了PM_2.5在近地面累积,春夏季则相反.     

Supervisor-Directed Emotional Labor as Upward Influence: An Emotions-as-Social-Information Perspective

To access organizational resources, subordinates often strive to influence supervisors' impressions. Moreover, subordinates' interactions with supervisors are known to be ripe with emotions. Nevertheless, research on upward impression management has rarely examined how subordinates' emotion regulation in supervisor interactions may shape their tangible outcomes. The present study introduces subordinates' emotional labor toward supervisors as a novel means of upward influence. Building on the emotions-as-social-information model, we propose that supervisor-directed emotional labor indirectly relates with supervisory reward recommendations by shaping supervisors' liking and perceived competence of subordinates. Moreover, we cast supervisors' epistemic motivation as a boundary condition for these indirect relations. We tested these notions using time-lagged data from 377 subordinates and 91 supervisors. When supervisors' epistemic motivation was higher (but not lower), (1) supervisor-directed surface acting related negatively with supervisors' liking and perceived competence of subordinates and (2) supervisor-directed deep acting related positively with supervisors' liking of subordinates. Liking and perceived competence, in turn, related positively with supervisors' willingness to recommend subordinates for organizational rewards. These findings highlight supervisor-directed emotional labor as an upward impression management strategy with both beneficial (deep acting) and detrimental (surface acting) implications, and they illustrate important mechanisms and a key contingency factor for these consequences.     

阻尼隔声板在噪声控制工程上的应用

对隔声材料的隔声功能进行了分析,根据两种以上不同质的复合材料可避开各自的阻隔波谷,能更有效地提高阻隔宽频噪声的总体性能的声学原理,提出了安装有阻尼层的隔声板,可有效提高隔声板的隔声量。     

城市污水处理系统真核微生物群落特性与地域性差异

城市污水处理厂是控制水污染、保证城市与人类可持续发展的重要设施.真核微生物作为活性污泥系统中不可或缺的一部分,在指示活性污泥性质、预测出水水质、强化净化效果、保障系统稳定运行过程中发挥着重要作用.本研究以来自北京、深圳和无锡的14个城市污水处理厂的61份样品为研究对象,采用18S r DNA高通量测序技术并结合多种生态学及统计学相关分析方法,探讨了活性污泥系统内真核微生物群落特性与地域性差异.结果表明,不同空间尺度下,活性污泥系统内真核微生物群落优势种群组成相似,在Devision水平上,群落优势种群主要由真菌、原生动物(纤毛亚门)和后生动物组成,三者相对丰度之和高达86. 22%～89. 40%.不同城市污水处理厂活性污泥系统内真核微生物多样性存在差异,无锡群落的多样性(丰富度和香农-威纳多样性指数)最高,北京的最低,且3个城市的活性污泥系统内真核微生物群落结构存在显著的地域性差异. partial mantel test和多元回归矩阵分析结果表明,曝气池混合液温度和出水总氮浓度与活性污泥系统内真核微生物群落结构的相关性较强.研究结果深化了对污水处理系统中真核微生物的认识.     

小麦籽粒镉含量影响因素Meta分析和决策树分析

快速的城市化、工业化和农业集约化造成了严重的土壤问题,如土壤酸化和镉污染等,严重威胁着中国的粮食安全和人体健康.小麦是中国第二大粮食作物,对镉有较强的积累能力.探明小麦籽粒镉含量的影响因素对保障小麦安全生产至关重要.然而,目前对小麦籽粒镉含量的影响因素还缺乏全面和定量的分析.对近10年发表的56篇相关论文进行Meta分析和决策树分析,结果表明,土壤样点中镉含量超过农用地土壤污染风险筛选值的比例为52.6%,小麦籽粒镉含量超过食品安全国家标准(0.10 mg·kg^-1,GB 2762-2017)的比例为64.1%.土壤理化性质中,pH、有机质、有效磷和土壤全镉含量是影响小麦籽粒镉含量的重要因素.土壤的pH≤5.5和5.5-1≤土壤有机质含量<30 g·kg^-1时,小麦籽粒镉含量超标率最高,为61.0%.农田土壤的pH≥7.1且全镉含量<1.60 mg·kg^-1时有利于小麦安全生产.不同小麦品种籽粒镉含量...     

2012年秦皇岛市夏秋异常降水及其影响评估简

2012年秦皇岛市夏秋季降水异常偏多,暴雨洪涝、地质灾害严重,给工农业生产及交通航运等带来严重损失。利用统计分析方法对6～11月秦皇岛异常降水进行分析,结果表明：6～11月连续6个月降水偏多,为1955年有气象记录以来唯一年份;11月全市降水偏多5倍以上,创有气象记录以来极值;7下8上区域性暴雨范围大,持续时间长,尤其8月3～4日受台风“达维”影响,出现了近50 a最大洪涝。在分析降水异常基础上,对引起的气象灾害及其影响进行了分析。