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601.
Chen Xun-lai Feng Ye-rong Li Jiang-nan Lin Wen-shi Fan Shao-jia Wang An-yu Fong Soikun Lin Hui 《Environmental Modeling and Assessment》2009,14(3):351-363
The atmospheric haze over the Pearl River Delta (PRD) was investigated by using the Models-3 Community Multi-scale Air Quality
modeling system with meteorological fields simulated by the Fifth-generation National Center for Atmospheric Research/Penn
State University Mesoscale Model (MM5) from September 26th to September 30th, 2004. The model-simulated meteorological elements
and particulate matter with aerodynamic diameter less than 10 μm (PM10) were compared with observations at four air quality-monitoring stations. The results showed that MM5 successfully reproduced
the diurnal variations of temperature, wind speed, and wind directions at these stations. The temporal variations of the simulated
values were consistent with those of the observed (such as temperature, wind speed, and wind direction). The correlation coefficient
was 0.91 for temperature and 0.56 for wind speed. The modeling results show that the spatial distributions of simulated PM10 were closely related to the source emissions indicating three maxima of PM10 over the PRD. The sea–land breezes diurnal cycle played a significant role in the redistribution and transport of PM10. Nighttime land breeze could transport PM10 to the coast and the sea, while daytime sea breeze (SB) could carry the accumulated PM10 offshore back to the inland cities. PM10 could also be transported vertically to a height of up to about 1000 m because of strong turbulence in the SB front. Process
analyses indicated that the emission sources and the vertical diffusion were the major processes to influence the concentrations
of particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5). 相似文献
602.
表面活性剂强化抽出处理含水层中DNAPL污染物的去除特征 总被引:1,自引:0,他引:1
为明确表面活性剂强化抽出处理含水层中DNAPL污染物过程中表面活性剂的增强修复效果,及DNAPL自身理化性质和介质孔径的影响,利用数码图像分析技术对1,2-二氯乙烷和四氯乙烯2种DNAPL在石英砂填充的二维砂箱中的抽取迁移过程进行了实验模拟研究,并对抽出水样中DNAPL的浓度进行了测试分析。结果表明,实验条件下加入低浓度(0.18%)的十二烷基苯磺酸钠(SDBS)大幅提高了对弱透水层截留的2种DNAPL聚集体的抽出处理效率。1,2-二氯乙烷在该表面活性剂溶液中的表观溶解度远高于四氯乙烯,因此其短时间内的绝对去除率更高。SDBS强化抽出处理DNAPL的作用机理以增溶作用为主,而其增流作用使DNAPL迁移流动后分布面积增大,增加了与表面活性剂溶液接触的面积,对增溶作用起到促进效果。细粒介质中DNAPL迁移后的最大分布面积较大,因此体系中DNAPL的溶解速率较高。在DNAPL聚集体质量与水力梯度固定的条件下,油水界面张力越低,DNAPL的密度越大,DNAPL垂向迁移的风险就越大。本研究为修复工程中如何依据DNAPL种类与场地多孔介质的情况选择表面活性剂提供了参考。 相似文献
603.
604.
Accidents in the process industry could be prevented or reduced by having good safety management measures. Such preventive measures could be further improved through the experiences and lessons learnt from past accidents. Therefore, analysis results of past accidents are valuable sources of information for determining root causes and as case material to prevent and reduce the adverse consequences of accidents in the process industry.This paper looks at accidents in the process industry that have occurred in the past 10 years from 1997 to 2006 in Sri Lanka to gain an understanding of the nature and consequences of accidents. Lessons and main areas of concern to improve safety in the Sri Lanka process industry are discussed. The analysis is done for different event types based on specific operating process stage during which the accident occurred such as processing, loading and unloading, repair and maintenance and storage, the immediate effect types such as fire, explosion, chemical releases and emissions and the consequences of each accident. Fire incidents were observed in 38 accidents analyzed. The results show that the highest number of accidents has occurred during processing operations followed by accidents during maintenance and repair work. The cause analysis shows that many accidents have occurred due to technical and human failures.The accidents are then classified according to the severity of the consequences in order to compare the nature of accidents experienced in Sri Lanka with respect to accidents in other countries in the world. 相似文献
605.
606.
汶上县生态农业发展的制约因素及改善措施 总被引:1,自引:0,他引:1
通过对影响汶上县生态农业发展制约因素的分析,结合当地实际,从引导农民转变思想认识、发挥政策引导作用等方面入手,提出了汶上生态农业发展的改善措施、发展方向。 相似文献
607.
汉江流域生态补偿效益评价指标体系有利于准确分析生态补偿资金的流向和效用,评价生态补偿政策的实施效果,进一步完善生态补偿机制。本着全面性:科学性、系统性、可操作性和导向性原则,选取经济社会发展、水源涵养和水资源节约、环境污染治理、环境监管能力建设4个方面共28项指标,构成汉江流域生态补偿效益评价指标体系,并采用层次分析法对评价指标体系进行权重分析。结果表明:现阶段汉江流域的生态补偿资金应首先用于上游地区的水源涵养和环境污染治理工作,以退耕还林工程、天然林保护工程、水土保持工程和生态移民工程为重点任务。 相似文献
608.
为了从源头上提高工业项目整个过程的安全绩效,基于安全知识设计的实践性、分散性和两重性等特点,对工业项目安全设计各阶段的知识流动进行阐述,提出安全设计策划、安全设计展开和安全设计评价各阶段的知识获取、存储、共享应用和创新,并应用知识管理的思想对基于安全知识的安全设计持续改进流程进行探讨。得出安全设计能有效管理并扩充安全知识数据库,供工业项目各参与方使用,并不断交流与深化改进工业项目的安全设计,使安全知识能在整个行业内广泛共享和再利用。 相似文献
609.
Michael A. Gebers Author Vitae 《Journal of Safety Research》2010,41(4):323-330
Introduction
This study evaluated California's traffic violator school (TVS) citation dismissal policy.Method
This study identified and compared two large samples of drivers either completing a TVS (N = 210,015) or convicted of a traffic citation (N = 168,563).Results
Prior to adjudication, the TVS group had characteristics (e.g., lower prior conviction rate and smaller proportion of males) that were predictive of a lower subsequent crash risk. However, the TVS group exhibited significantly more crashes than did the convicted group in the subsequent one-year period. The difference (4.83%) increased to 10% after adjusting for the more favorable characteristics of the TVS group. The TVS group also had a higher adjusted subsequent crash rate at each prior driver record entry level, reflecting a loss in the general and specific deterrence of the non-conviction masked status of TVS dismissed citations. It was reported that the TVS dismissal policy results in approximately 12,300 additional crashes annually with economic costs of approximately $398,000,000.Conclusions
The avoidance of licensing actions resulting from the dismissal policy assists in explaining why the driving public is exposed to an increased crash risk. A number of recommendations are offered to reduce the negative traffic safety impact of the TVS citation dismissal policy. 相似文献610.