Kang Yan-ming

Comparison of Vertical Distribution of Optical Properties of Aerosols between Haze and Floating Dust Weather in Shanghai Based on Micro Pulse Lidar

A comparative study on the vertical distributions of aerosol optical properties during haze and floating dust weather in Shanghai was conducted based on the data obtained from a micro pulse lidar. There was a distinct difference in layer thickness and extinction coefficient under the two types of weather conditions. Aerosols were concentrated below 1 km and the aerosol extinction coefficients ranged from 0.25 to 1.50 km−1 on haze days. In contrast, aerosols with smaller extinction coefficients (0.20–0.35 km−1) accumulated mainly from the surface to 2 km on floating dust days. The seasonal variations of extinction and aerosol optical depth (AOD) for both haze and floating dust cases were similar—greatest in winter, smaller in spring, and smallest in autumn. More than 85% of the aerosols appeared in the atmosphere below 1 km during severe haze and floating dust weather. The diurnal variation of the extinction coefficient of haze exhibited a bimodal shape with two peaks in the morning or at noon, and at nightfall, respectively. The aerosol extinction coefficient gradually increased throughout the day during floating dust weather. Case studies showed that haze aerosols were generated from the surface and then lifted up, but floating dust aerosols were transported vertically from higher altitude to the surface. The AOD during floating dust weather was higher than that during haze. The boundary layer was more stable during haze than during floating dust weather.

Solar Radiation at Surface for Typical Cities in the Arid and Semi-Arid Area in Xinjiang, China Based on Satellite Observation

Xinjiang, a region of China with arid and semi-arid areas, has abundant solar incidence with 166.5×104 km2 and diverse underlying surface. The meager number of surface radiation observatories cannot meet the need for efficient exploration of solar energy. In this study we classified Xinjiang into three regions: southern Xinjiang, northern Xinjiang and Tu-Ha region and applied satellite data to provide the surface solar radiations temporal distribution for 10 typical cities. The study is focused on seasonal, annual and variations of all sky downward shortwave radiation flux at surface based on 24-year satellite dataset GEWEX-SRB from the WCRP/GEWEX (World Climate Research Program/Global Energy and Water Cycle Experiment) from 1984 to 2007. The results are as follows. In general, the monthly average solar radiation flux for the cities in the Tu-Ha region was the largest followed by the south Xinjiang and northern Xinjiang. The solar radiation in the most northern cities were less than 150.0 W/m2 in winter, the minimum is 138.7 W/m2, while the other cities were greater than 150.0 W/m2. The maximum of monthly solar flux for the Tu-Ha region, southern and northern Xinjiang was 400.0 W/m2.

Comparison of I–V Characteristics in Two Types of Wire-Plate Electrostatic Precipitators

Publisher Summary This chapter experimentally explains the effects of some geometric parameters on the I-V characteristics of two different types of electrostatic precipitators (ESPs), one is a conventional wire-plate ESP, the other is a tri-electrode ESP. The performance of ESPs is usually obtained under different geometric parameter values and operation conditions. The ESP is one of the most commonly applied particulate control devices to reduce fly-ash emission from coal-fired power stations, cement industries, and many other industrial processes. The collection efficiency of an ESP is increased as corona power increases. However, the ideal design of an ESP is changed when high-resistivity dust particles deposit on the surface of collecting plates. One of the major problems for a wire discharge system is back corona. The results show that in a tri-electrode system, the corona current will be limited in the zone between two additional electrodes. The width of the cross channel should take the same magnitude as in wire-duct ESPs with the comparison of the two types of ESPs.