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71.
72.
Smodis B 《Journal of environmental management》2007,85(1):121-128
In the framework of the IAEA programmes, Member States involved in air pollution studies using nuclear analytical techniques have harmonized their methodologies. Participants characterising chemical composition of size fractionated airborne particulate matter based their methodology on a common type of air sampler, centralised data collection and evaluation, and the same kind of data processing. Institutions involved in biomonitoring air pollution identified appropriate organisms to be applied at a regional scale, and harmonized procedures for sample preparation and analysis, as well as data processing and presentation. Both metrology approaches have been validated and disseminated in many Member States. 相似文献
73.
自激振荡磨料射流的基本理论与初步试验 总被引:3,自引:0,他引:3
自激振荡磨料射流是在自激振荡脉冲射流和前混合磨料射流基础上,提出的新型射流。为此,重点讨论了自激振荡磨料射流喷嘴的结构和工作原理,分析了脉冲频率和幅值等参数对磨粒加速效果的影响。根据初步研究表明,磨粒速度受脉冲频率和幅度影响很大,磨粒速度可超过前混合磨料射流中磨粒的速度,最大钻孔速度比前混合磨料射流提高41% 。这一成果有望用于坚硬物料的切割和特种加工、石油钻井、大洋采矿、难采矿体的开采、坚硬岩石巷道(遂道)掘进、表面清洗等领域。 相似文献
74.
循环磨料射流是磨料射流的一种重要形式。循环磨料浆液被高压水加速后直接输入喷嘴,构成具有强大打击力的磨料射流;特别适用于锻件、轧制件的除鳞除锈,铸件清砂等表面处理。要保证循环磨料射流在工业中应用,必须首先解决两个关键问题,即循环磨料射流浆体在管路中的正常流动、磨料的悬浮与沉降规律以及过碎的微小磨粒的剔除,以满足高效、连续的作业。本文论述了循环磨料射流的工作原理和主要工作参数的确定方法。 相似文献
75.
根据在北京市道路路面附近颗粒物 (TSP)的实测数据 ,分析了道路峡谷内 TSP的粒径分布 ,以及粒径分布与峡谷结构、距地面距离的关系 ,说明了影响粒径分布的主要因素。 相似文献
76.
77.
S. Giordano P. Adamo E. Pittao R. Bargagli 《Environmental pollution (Barking, Essex : 1987)》2009,157(10):2798-2805
To define a harmonized methodology for the use of moss and lichen bags as active monitoring devices of airborne trace elements in urban areas, we evaluated the element accumulation in bags exposed in Naples in different spring weather conditions for 6- and 12-weeks. Three different pre-exposure treatments were applied to moss and lichen materials: water-washing, acid-washing and oven-drying. During the different exposure periods in the Naples urban environment the moss accumulated always higher amounts of elements (except Hg) than lichens and the element accumulation increased during wetter weather and higher PM10 conditions. The oven pre-treatment did not substantially modify the morphology and element composition of moss and the exposure in bags of this material for 6-weeks was sufficient to detect the pattern of airborne trace elements. 相似文献
78.
K.G. Andersson T. Mikkelsen P. Astrup S. Thykier-Nielsen L.H. Jacobsen S.C. Hoe S.P. Nielsen 《Journal of environmental radioactivity》2009,100(12):1005-1011
The ARGOS decision support system is currently being extended to enable estimation of the consequences of terror attacks involving chemical, biological, nuclear and radiological substances. This paper presents elements of the framework that will be applied in ARGOS to calculate the dose contributions from contaminants dispersed in the atmosphere after a ‘dirty bomb’ explosion. Conceptual methodologies are presented which describe the various dose components on the basis of knowledge of time-integrated contaminant air concentrations. Also the aerosolisation and atmospheric dispersion in a city of different types of conceivable contaminants from a ‘dirty bomb’ are discussed. 相似文献
79.
A comparison between superfine magnesium hydroxide powders and commercial dry powders on fire suppression effectiveness 总被引:1,自引:0,他引:1
Kaiqian Kuang Xin Huang Guangxuan Liao 《Process Safety and Environmental Protection》2008,86(3):182-188
The effectiveness of superfine magnesium hydroxide powders and commercial dry powder in fire suppression were compared in a laboratory-scale, immovable fire suppression apparatus. The investigation focused on their suppression effectiveness under various pressures. It likewise studied the relationship between the powders’ surface structures and their effectiveness on fire suppression. The microcosmic structure of the powders was observed by scanning electron microscope (SEM), while the Thermal Gravity Analysis (TGA) technique was used to analyze the thermal behavior of the superfine magnesium hydroxide powders. By analyzing the results, it could be concluded that the pressure, the particle size, and the microcosmic structure of the powders’ surface mainly decide the capability of the powders to extinguish the fire. Comparing this with commercial dry powders, superfine magnesium hydroxide powders extinguished the fire in less than 10 s. 相似文献
80.
Vanderstraeten P Lénelle Y Meurrens A Carati D Brenig L Offer ZY 《Environmental monitoring and assessment》2007,132(1-3):253-262
We report and analyze data on the PM10 fraction of airborne particles measured at five recording stations in the Brussels
region from October 2002 till September 2003. These stations are representative of the various activity sectors of the Brussels
urban area. The objective was the determination of the origin of the PM10 particles (particles up to 10 μm) that are recorded
in that region in order to follow the EU directives concerning tolerance level of airborne particles concentration. In order
to evaluate the impacts of local and external factors that inject solid particles in the atmosphere of Brussels we compared
concentration data from working and not working (holidays) periods. Moreover, we also compared concentrations from periods
of agricultural activity and rest in the Brabant provinces surrounding the Brussels region for various crop types. The results
lead to the conclusion that the impact or urban traffic is rather limited while that of the agricultural activities is important.
Moreover, there appears a clear-cut distinction between different types of crops. 相似文献