The effective medium approximation (EMA) theory is the basis of a capacitance sensor used for concen-tration measurementof a particulate solid flow, its measurementresultis independenton particle size. In existence of...The effective medium approximation (EMA) theory is the basis of a capacitance sensor used for concen-tration measurementof a particulate solid flow, its measurementresultis independenton particle size. In existence ofparticle agglomeration or aggradation, however, it is found that the effective permittivity of a gas/solid mixture is de-pendent on particle size. In this paper, a parallel plate, differential capacitance sensor is utilized to investigate theinfluence of particle size on the effective permittivity of the mixture in such a case. Static experiments using threematerials including glass, limestone and quartz particles were carried out in an off-line manner. The volume fractionof particles being tested ranged from20×10-6to 600×10-6, while the particle size was between 3 and 100μm.Experimental results showthat the effective permittivity of a particle-gas mixture with particle agglomeration is largerthan that predicted by EMA and the smaller the particle size, the larger the effective permittivity. The experimentprocess and analysis results are discussed in detail in the paper.展开更多
Daily samples of aerosol（n=27） were collected from September 21 st to October 4th, 2013 in Fukang（44.17°N, 88.45°E, 475 m a.s.l.）, Xinjiang, Northwest China. The enrichment factors（EFc） of selected 49 ...Daily samples of aerosol（n=27） were collected from September 21 st to October 4th, 2013 in Fukang（44.17°N, 88.45°E, 475 m a.s.l.）, Xinjiang, Northwest China. The enrichment factors（EFc） of selected 49 elements showed that the aerosols had extremely high concentrations of heavy metals, probably indicating their anthropogenic origins. Morphology of individual aerosol particles was determined by scanning electron microscopy and energy-dispersive X-ray microanalysis. Based on morphology and elemental composition, the particles were clustered into three dominant types：（Ⅰ） crustal originated particles： Si/Al-rich particles（36%） and Si/Fe-rich particles（24%）;（Ⅱ） mixed source particles; and（Ⅲ） pollution derived particles： Pb-rich particles（10%）. The backward trajectories were calculated using the HYSPLIT model, and the results indicated the different anthropogenic sources for heavy metals in Fukang aerosols. Air mass from north was identified as the most polluted source when compared to south and west.展开更多
文摘The effective medium approximation (EMA) theory is the basis of a capacitance sensor used for concen-tration measurementof a particulate solid flow, its measurementresultis independenton particle size. In existence ofparticle agglomeration or aggradation, however, it is found that the effective permittivity of a gas/solid mixture is de-pendent on particle size. In this paper, a parallel plate, differential capacitance sensor is utilized to investigate theinfluence of particle size on the effective permittivity of the mixture in such a case. Static experiments using threematerials including glass, limestone and quartz particles were carried out in an off-line manner. The volume fractionof particles being tested ranged from20×10-6to 600×10-6, while the particle size was between 3 and 100μm.Experimental results showthat the effective permittivity of a particle-gas mixture with particle agglomeration is largerthan that predicted by EMA and the smaller the particle size, the larger the effective permittivity. The experimentprocess and analysis results are discussed in detail in the paper.
基金supported by the National Natural Science Foundation of China(Nos.41201065,41121001,41261017,41171057,41161012)the fund for Creative Research Groups of China(No.41121001)+3 种基金the foundation for Excellent Youth Scholars of CAREERI,CAS(No.51Y251B51)the SKLCS Foundation(No.SKLCSZZ-201201-01)the National Basic Research Program of China(Nos.2010CB951003,2010CB951404)the Knowledge Innovation Project of the Chinese Academy of Sciences(No.KZCX2EW-311)
文摘Daily samples of aerosol（n=27） were collected from September 21 st to October 4th, 2013 in Fukang（44.17°N, 88.45°E, 475 m a.s.l.）, Xinjiang, Northwest China. The enrichment factors（EFc） of selected 49 elements showed that the aerosols had extremely high concentrations of heavy metals, probably indicating their anthropogenic origins. Morphology of individual aerosol particles was determined by scanning electron microscopy and energy-dispersive X-ray microanalysis. Based on morphology and elemental composition, the particles were clustered into three dominant types：（Ⅰ） crustal originated particles： Si/Al-rich particles（36%） and Si/Fe-rich particles（24%）;（Ⅱ） mixed source particles; and（Ⅲ） pollution derived particles： Pb-rich particles（10%）. The backward trajectories were calculated using the HYSPLIT model, and the results indicated the different anthropogenic sources for heavy metals in Fukang aerosols. Air mass from north was identified as the most polluted source when compared to south and west.
