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871.
Study on Size Distributions of Airborne Particles by Aircraft Observation in Spring over Eastern Coastal Areas of China 总被引:2,自引:0,他引:2
The authors studied the size distributions of particles at an altitude of 2000 m by aircraft observation over eastern costal areas of China from Zhuhai, Guangdong to Dalian, Liaoning (0.3,7-30μm, 57 channels,including number concentration distribution, surface area concentration distribution and mass concentration distribution). In these cities, the average daily concentrations of PM10 are very high. They are among the most heavily polluted cities in China. The main pollution sources are anthropogenic activities such as wood, coal and oil burning. The observed size distributions show a broad spectrum and unique multi-peak characteristics, indicating no significant impacts of individual sources from urban areas. These results are far different from the distribution type at ground level. It may reflect the comprehensive effect of the regional pollution characteristics. Monitoring results over big cities could to some extent reflect their pollution characteristics. 相似文献
872.
Castellón province houses the nucleus of ceramics production in Spain (93%). This nucleus, located around in the villages of Castellón, Villarreal, Alcora and Onda, has gone through a special process of industrial expansion. The emissions, most of them of particulate material, can constitute a real environmental problem. A study designed to identify the crystalline and glassy phases in the depositable particulate material has been carried out by SEM/EDX and X-ray diffraction methods. Quartz, calcite, illite, kaolinite, chlorite, and feldspars have been the main crystalline phases identified. The number of spherical morphology particles found in the depositable material is remarkable. The vitreous material found was spherical nodules. Due to the shape, size (1–10 μm), and chemical composition of these particles, they can be excellent tracers of the ceramics industry emissions.The presence of Zn, Ba, or Fe are due to the massive use of these substances as opacifying and pigmentation agents in many ceramics frits and glaze compositions. This fact gives a valuable information that will facilitate the studies guided to obtain important aims such as: toxicology, average size of a particle, formation mechanisms, etc. 相似文献
873.
本文采用基于不可逆热力学原理的韧性金属复杂应力损伤演化模型,对ABAQUS二次开发将损伤模型引入有限元计算,实施含腐蚀传动装置磨粒磨损分析;磨粒-传动轴-配合面耦合模型中,磨粒采用三维球形分形模型,对点蚀和面蚀配合面与磨粒微观接触时损伤演化及传动特性变化进行模拟,发现磨粒挤入配合面后应力三轴度增大,传动轴转动数周后接触面即出现凸峰与沟犁,而且缺陷间存在损伤连通趋势,使结构传动运动能力快速下降;考虑环境温度循环,温度升高使磨粒局部产生应力梯度,对结构传动能力也有不利影响。基于材料损伤演化模型建立细观磨粒磨损与宏观传动装置统一的模拟方法,实现了海洋环境下小间隙配合面磨粒磨损计算,有效预测了传动装置性能退化过程。 相似文献
874.
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876.
Nils K. Lünsdorf Istvan Dunkl Burkhard C. Schmidt Gerd Rantitsch Hilmar von Eynatten 《Geostandards and Geoanalytical Research》2014,38(1):73-94
Raman spectroscopy of carbonaceous material (RSCM) is frequently used to determine metamorphic peak temperatures from the structural order of carbonaceous material enclosed in metasediments. This method provides a quick, robust and relatively cheap geothermometer. However, the comparability of the RSCM parameter is low as there are at least three major sources of biasing factors. These sources are the spectral curve‐fitting procedure, the sample characteristics itself and the experimental design including the used Raman system. To assess the impacts of the biasing factors on RSCM, a series of experiments was performed. The experiments showed that curve‐fitting is strongly influenced by individual operator‐bias and the degrees of freedom in the model, implying the need for a standardised curve‐fitting procedure. Due to the diversity of components (optics, light detection device, gratings, etc.) and their combinations within the Raman systems, different Raman instruments generally give differing results. Consequently, to estimate comparable metamorphic temperatures from RSCM data, every Raman instrument needs its own calibration. This demands a reference material series that covers the entire temperature calibration range. Although sample heterogeneity will still induce some variation, a reference material series combined with standardised curve‐fitting procedures will significantly increase the overall comparability of RSCM data from different laboratories. 相似文献
877.
The light curves of solar ?ares in the impulsive phase are complex in general, indicating that multiple physical processes are involved in. With the GOES (Geostationary Operational Environmental Satellite) observations, we ?nd that there are a subset of ?ares, whose impulsive phases are dominated by a period of exponential growth of the emission measure. The ?ares occurred from January 1999 to December 2002 are analyzed, and the results from the observations made with both GOES 8 and GEOS 10 satellites are compared to estimate the instrumental uncertainties. Their mean temperatures during this exponential growth phase have a normal distribution. Most ?ares within the 1σ range of this temperature distribution belong to the GOES class B or C, with the peak ?uxes at the GOES low-energy channel following a log-normal distribution. The growth rate and duration of the exponential growth phase also follow a log- normal distribution, in which the duration is distributed in the range from half a minute to about half an hour. As expected, the growth time is correlated with the decay time of the soft X-ray ?ux. We also ?nd that the growth rate of the emission measure is strongly anti-correlated with the duration of the exponential growth phase, and the mean temperature increases slightly with the increase of the growth rate. The implications of these results on the study of energy release in solar ?ares are discussed in the end. 相似文献
878.
The CrossScale mission will advance our understanding of fundamental plasma processes in collisionless plasmas. It will exploit the excellent natural plasma laboratory provided by the Earth’s magnetosphere and the near-Earth solar wind and, in particular, carry out multi-scale studies that will strongly complement plasma studies in ground-based laboratories. Previous studies of collisionless plasmas in space environments across the solar system have shown the ubiquitous nature of suprathermal particles and that these particles exhibit a power-law energy spectrum. In this paper we discuss the great significance of these suprathermal particles for CrossScale studies. We show that the presence of these particles is a natural consequence of the collisionless regime as they can propagate across the heliosphere with little spectral change and are not thermalised by collisions. They are a key indicator of the non-equilibrium nature of collisionless plasmas and an important source of free energy that can drive plasma processes. We discuss how these suprathermal particles influence the overall properties of the plasma. In particular, the energy distribution of particles follows a Kappa, rather than Maxwellian, distribution and thus the plasma does not have a single thermodynamic temperature. We also discuss the importance of the suprathermal tail as a tool to diagnose the processes responsible for particle energisation in collisionless plasmas. Such energisation is a common feature in collisionless plasmas, especially in terms of the primary science targets for CrossScale: reconnection, shocks and turbulence. Finally we also touch on the value of using CrossScale studies to provide ground truth measurements for a number of astrophysical techniques that exploit the effects of energetic electrons in the distant universe. Throughout the paper, we stress that suprathermal (30 keV-1 MeV) measurements are essential to fully characterise particle distributions. We show that such measurements will benefit greatly from the improved spatial and temporal resolution (compared to Cluster) that is proposed for the HEP instrument on CrossScale. 相似文献
879.
硅酸盐钻井液体系是一种以无机盐为主要处理剂的防塌抑制性钻井液,具有物理封堵和化学加固井壁双重防塌作用,能有效的降低井壁的渗透率、阻止压力传递,且具有较好的流变特性、无毒、无荧光、成本低,被认为是具有发展前景的水基钻井液之一。在碳质泥岩钻探中经常遇到的问题有:漏失、坍塌、掉块、涌水等,给安全钻井带来很大麻烦。同时,为了满足工程/水文地质资料获取与评价要求,铁路勘察对复杂地层的处理有相对严格的要求,如避免使用水泥封孔等,本文研究的硅酸盐钻井液可以有效的解决碳质泥岩钻探中的上述问题,并能提高岩心采取率和机械钻速。 相似文献
880.