“腊月二十四，掸尘扫房子”

民间传说扫年 “扫年”又称为“扫尘”，关于它的由来，还有一个颇为诡异的故事。

Characterization of Dust and Non-dust Aerosols with SEM/EDX

Total suspended particulate （TSP） samples were collected at three sites along the coast of Qingdao, China, before and during a major dust storm in March, 2002. For comparison, PM10（particulate matter with aerodynamic diameters less than 10μm） samples were collected at one of the three sites. The morphological observation and compositional analysis of bulk and individual particles were performed by using scanning electron microscopy equipped with an energy dispersive X-ray system （SEM/EDX） for the TSP and PM10 samples. The results showed that the particles of different kinds of morphology had different elemental compositions, but the particles of similar morphology did not always have the same elemental composition for non-dust samples. The morphology and composition of non-dust particles were different at different sites. The fractal and spherical particles existed mainly in the coarse fraction for non-dust samples, while in the fine mode （〈 10μm） there were floccules formed by fine particles flocking together and containing crustal elements. Compared with the non-dust particles, the dust particles were more homogeneous in terms of morphology, particle size and composition. Particles with irregular shapes and well-distributed sizes dominated in the dust samples, containing crustal elements such as Mg, A1, Si, Ca, Fe, etc. The high sulfur content indicated that homogeneous and heterogeneous reactions took place on the surfaces of the dust particles in the specific environment of Qingdao.

Microstructure of ferrospheres in fly ashes: SEM, EDX and ESEM analysis

Ferrospheres in fly ashes from a coal-fired power plant were extracted by a magnetic separation technique and their microstructure was studied by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and environmental scanning electron microscopy (ESEM). Ferrospheres in fly ashes show significant iron enrichment compared to their respective fly ashes. Iron oxides in ferrospheres mainly occur as minerals magnetite (Fe3O4) and hematite (α-Fe2O3), which are derived mainly from the decomposition and oxidation of iron-bearing minerals in coal during combustion. EDX data indicate that ferrospheres also contain Si, S, Al and Ca resulting from quartz, mullite, anhydrite and amorphous materials. A large percentage of ferrospheres are commonly 5～50 μm in size. The microstructure of ferrospheres includes smooth, polygonal, dendritic, granular and molten drop characteristics. SEM coupled with EDX provided fast and accurate results of the microstructure and chemical composition of ferrospheres, and helped us to assess environmental issues related to the disposal and utilization of fly ashes.

春天的节日--关于过年的话题：下篇 花样年华绽放在春天的美丽

这是一个崇尚自由与个性的花样年华。所有绽放在春天的美丽都有着动人的质地和光泽。不管是对古老经典的沉迷与眷念还是对现代时尚的倾慕与追逐。都一样能够找到充足的理由——只要是发自内心的热爱。只要能顺从和张扬我们自然、本真的生命状态——都一样能够得到认可和接受。

Experimental Investigation of Dust Deposit within Ceramic Filter Medium during Filtration-Cleaning Cycles

The penetration and deposit of particles within the medium is thought to be one reason that the residual pressure drop of the rigid ceramic filter increase with cycle number.In this study,the change in the microstructure of a single layer ceramic filter candle during filtration-cleaning cycle was observed by scanning electron microscope(SEM) and the resistance property of the filter was monitored accordingly.The experimental results show that there exists a serious dust deposit within the filter medium,especially at the surface region.This should be responsible for the decrease of the filter permeability.The deposit law of dust in the filter medium during filtration-cleaning cycle was then studied by measuring the deposit depth,the deposit amount,the particles distribution within the medium,the size distribution of deposited particles,and so on.Particles migration and fine particles penetration were found to be the main reasons,for which dust deposit within the filter medium became aggravated with cycle number.Based on a differential form of Ergun equation,an expression for the pressure drop of a used ceramic filter was developed with a good agreement with experimental results.Then,the effect of dust deposit on the residual pressure drop was studied at the different face velocities and dust sizes.It was found that face velocity and dust size significantly influence dust deposit within filter medium,and then the operation performance of the filter.

Detection of coal dust in a mine using optical tomography

A dust concentration imaging system based on optical tomography is proposed to monitor concentration variations of coal dust in a mine.Concentration profiles,rather than just a point value,of coal dust concentrations are the goal of this method.An optical sensor array is employed to realize an optical sensing field of the coal dust concentration during on-line monitoring.A novel image reconstruction algorithm,called the simultaneous iterative reconstruction technique(SIRT),is compared to the well known linear,back projection algorithm(LBP).The SIRT was applied to the present problem and tested by modeling.The disadvantage of the SIRT is a slow speed but some improvements have been made by adding a weighting function that reduces the relative error to 1.7% from 3.1% for 50 iterations.The results of image reconstruction are presented for both simulated and real objects.They prove that the optical tomography technique,based on a multi-source fan projection scheme,can be an effective approach for estimating coal dust distribution.This system can be applied in real time for continuous measurements in a mine.

过年

年关在迩，一些同事见面就问我：要回去过年么？