偏光显微镜法在空气粉尘中石棉纤维鉴别中的应用

本文采用偏光显微镜法鉴别空气粉尘中的微量石棉纤维。经滤膜收集的粉尘样品通过高温灰化及酸洗过程去除大部分干扰物质,经乙醇分散后均匀沉积在玻璃片上,滴加具有固定折射率的浸油制成试片。在正交偏光系统下观察到粉体中存在纤维状颗粒,且纤维呈现四次平行消光特性,比对6种常见石棉的偏光显微镜图,综合分析试样粉尘的光学性质,推断样品中含有温石棉。     

组织管理对空中交通管制员工作能效的影响分析

综合借鉴SHELL模型和Reason模型的概念,参考国际民航组织《安全管理手册》,分析民航运行体系中组织管理对空中交通管制员工作能效的作用路径,提出组织管理对管制员工作能效产生积极影响的方法和建议.     

基于SARIMA-SVR组合模型的 空气质量指数预测

空气质量指数(AQI)在波动中既具有整体的时间序列线性特征和明显的季节性波动周期,又具有多种因素影响的不确定性,为了提高AQI的预测精度,基于Ri386 3.3.3和Matlab R2014a两种编程软件,提出了一种同时具有线性和非线性的复合特征的时间序列预测模型——SARIMA-SVR组合模型。以太原市2014年1月—2019年7月的AQI月均值数据为基础,利用SARIMA时间序列模型进行线性预测,利用SVR模型对残差进行非线性预测,加和得到组合预测模型的预测结果,分析比较SARIMA,SVR和SARIMA-SVR这3种模型的预测结果和平均绝对百分比误差。结果表明,组合预测模型发挥了2种模型各自的优势,相较于单一预测模型的预测结果而言,其预测精度更高,稳定性更好。通过此模型得到的空气质量预测结果不仅可为人们的日常生活提供指导,而且可为大气污染的防治工作提供科学依据和借鉴意义。     

An explorative study of corporate travellers’ perception at a German airport

The modern working environment is changing at a fast pace due to factors such as globalisation, digitalisation, and demographic trends. Taking an exploratory approach, this study examines how prevailing factors shaping the working world may influence the perception of business air travellers. Relevant factors are identified through a literature review, which results are confirmed by expert interviews (N = 11). Business travellers are surveyed (N = 67) at Munich Airport regarding their personal experiences and their evaluations of these identified factors. Their perceptions concerning the psychological and physical experience, digitalisation, age, and gender are examined in detail.Findings provide insights into the development of business air travel, with a focus on German business travellers. Despite the influence of advanced information and communications technology, survey results reveal that air travel might stay an essential part of the working world, as face-to-face meetings are not fully replaceable. Increasing multi-partner project work and flexible work structures could even lead into an increase of air travel. The study also delineates recommendations and research potential, such as the extension of the study in the light of the global COVID-19 pandemic. The question of how trends within the working world influence the perception of business related air travel is rarely studied. This study contributes to this gap in the scientific community.     

Does economic growth and energy consumption drive environmental degradation in China’s 31 provinces? New evidence from a spatial econometric perspective

The panel data analysis points to economic and social factors contributing to NO_x, PM_2.5, PM₁₀, SO₂, and VOCs in China’s 31 provinces. The spatial correlation analysis using Global and Local Moran’s I values indicates the existence of a significant and positive spatial autocorrelation with respect to environment, economy and energy, and the high spatial correlation is evident in the eastern region, covering the northern part of Yangtze River Delta, Huaihai Economic Zone, and the lower reaches of the Yellow River Economic Belt. The empirical estimation is performed through spatial lag and spatial Durbin models. All emitted air pollutants in 31 provinces have significant spatial dependence and strong spillover effects. There is an inverted U-shaped relationship between emitted air pollutants (NO_x, PM₁₀, VOCs, and PM_2.5) and per capita GDP, which follows the EKC hypothesis. The relationship between SO₂ and per capita GDP does not follow the EKC hypothesis. There is a positive relationship between pollutant emissions and coal consumption, which is consistent with current studies for various countries like Canada, Denmark, UK and US and regions like New York State. However, the effects of science and technology investment on air pollutants are mostly positive, which is not as policy expected.     

多传感器长途客车智能新风系统设计研究

本研究设计了一种结合二氧化碳传感器、PM2.5粉尘传感器、TVOC传感器来实现智能更新长途客车封闭空间内污浊空气的长途客车车载新风系统。本系统由各项传感器实时采集车厢内CO2、PM2.5、TVOC等数据上传至单片机,单片机判断各项数据是否超过设定阈值,若超过设定阈值,新风系统自动工作改变进、排风量;反之,新风系统不工作,实现智能控制。实验证明,本系统具有明显地改善长途客车内空气质量的效果,能够更好地保护人体健康。     

"利剑斩污"行动下石家庄市挥发性有机物的污染特性变化研究

为研究石家庄市在"利剑斩污"行动管控期和非管控期挥发性有机物(VOCs)的污染特性变化,在2个时间段内对石家庄市3个国控点进行采样分析。通过苏玛罐(SUMMA罐)进行样品采集,利用气相色谱/质谱联用(GC/MS)仪对石家庄市区3个国控点的VOCs进行定性定量检测分析。结果表明,监测期间主要的特征污染物是二氯甲烷、二氯丙烷、苯和甲苯。与非管控期间相比,管控期间各污染物的质量浓度均有所降低,总VOCs平均质量浓度降低45.107μg/m~3,二氯甲烷质量浓度降低8.796μg/m~3,二氯丙烷质量浓度降低3.750μg/m~3,苯质量浓度降低18.285μg/m~3,甲苯质量浓度降低16.895μg/m~3。大气环境调控策略的实施,有效降低了VOCs浓度,减少了空气污染程度,空气质量改善效果显著。"利剑斩污"行动期间采取的相关举措,对于制定常态化下VOCs的防治对策具有一定的参考价值。     

新型室内空气污染物——SVOC危害与研究进展

当今社会,室内空气质量受到越来越多的关注。研究表明,室内空气污染中除了大家熟知的甲醛、挥发性有机化合物,还有一种半挥发性有机化合物(SVOC)。目前,我国室内SVOC污染研究还处于起步阶段,相关研究还比较少。本文主要对现阶段室内SVOC污染状况及其健康风险评价内容进行梳理、分析与总结,推动室内SVOC相关研究发展,以完善我国室内空气污染物检测体系,提升室内环境安全水平。     

Measuring imported case risk of COVID-19 from inbound international flights --- A case study on China

With COVID-19 spreading around the world, many countries are exposed to the imported case risk from inbound international flights. Several governments issued restrictions on inbound flights to mitigate such risk. But with the pandemic controlled in many countries, some decide to reopen the economy by relaxing the international air travel bans. As the virus has still been prevailing in many regions, this relaxation raises the alarm to import overseas cases and results in the revival of local pandemic. This study proposes a risk index to measure one country's imported case risk from inbound international flights. The index combines both daily dynamic international air connectivity data and the updated global COVID-19 data. It can measure the risk at the country, province and even specific route level. The proposed index was applied to China, which is the first country to experience and control COVID-19 pandemic while later becoming exposed to high imported case risk after the epidemic centers switched to Europe and the US afterward. The calculated risk indexes for each Chinese province or region show both spatial and temporal patterns from January to April 2020. It is found that China's strict restriction on inbound flights since March 26 was very effective to cut the imported case risk by half than doing nothing. But the overall index level kept rising because of the deteriorating pandemic conditions around the world. Hong Kong and Taiwan are the regions facing the highest imported case risk due to their superior international air connectivity and looser restriction on inbound flights. Shandong Province had the highest risk in February and early March due to its well-developed air connectivity with South Korea and Japan when the pandemic peaked in these two countries. Since mid-March, the imported case risk from Europe and the US dramatically increased. Last, we discuss policy implications for the relevant stakeholders to use our index to dynamically adjust the international air travel restrictions. This risk index can also be applied to other contexts and countries to relax restrictions on particular low-risk routes while still restricting the high-risk ones. This would balance the essential air travels need and the requirement to minimize the imported case risk.     

离心式血液泵水力特性设计及其试验研究

借助商业软件NREC开展离心式血液泵的水力特性设计,其设计流量为5 L/min,设计转速为5000 r/min,得到离心叶轮和蜗壳的三维结构设计方案,并针对其全通道网格进行设计工况下三维流场的定常数值模拟研究.对其溶血性指标进行分析,发现离心式血液泵中95％ 区域切应力小于150 Pa,最大切应力小于500 Pa,满足人体对血液泵溶血性的要求.搭建离心式血液泵流量-压升特性试验测试平台,以质量分数为0.06％ 的黄原胶溶液为流动介质进行试验研究,试验结果显示在设计转速下的实际体积流量偏大于设计流量,整体压升在6550 Pa左右.