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Environmental Informatics Archives

ISSN 1811-0231 / ISEIS Publication Series Number P002

Copyright © 2006 ISEIS. All rights reserved.



  Paper EIA06-035, Volume 4 (2006), Pages 384-394 = complimentary

Tudy on Critical Point Threshold of Pollutant Emission Based on Modified Grey Clustering Model

W. G. Xu1,2, Q. Y. Zhang1*, H. Guo1 and Y. M. Wei1

1. Department of Environmental Engineering, Zhejiang University, Hangzhou, China 310027. *Corresponding author: qy_zhang@zju.edu.cn.

2. Hangzhou Command School of CAPF, Hangzhou, China 310023.



With the aim to attain quality standard of comprehensive grade, a new methodology is presented in this paper based on the modified grey clustering model for calculating the critical point threshold of single environmental pollutant emission. First, the new model is established to make a comprehensive evaluation for current system quality grade. Then, the exponential whiteness function is introduced into the modified grey clustering model, to replace the classical grey clustering model in which the linear whiteness function is generally used. And in the modified model, both intrinsic weight of index system and real weight are organically combined. When calculating the real weight, it is found that zero weight problems, which occur with the classical grey clustering model, can be overcome with the new model. Furthermore, with the modeling principle that a one to one corresponding relationship is established between each value of the index sample and each nonzero weight of various grades, the modified grey clustering model can be used to calculate the critical point threshold of single environmental pollutant emission to attain standard grade. Finally, as an application, the comprehensive grade of environmental atmospheric quality of Hangzhou Economic & Technological Development Area has been evaluated in 2003 year. It is indicated that the practical comprehensive grade is only grade III which has been above the standard grade’s upper limit. If the comprehensive grade agrees with grade II, the concentration of chief pollutant in this area, PM10, has to decrease more than 47.87%. That is to say, the concentration of PM10 has to be cut down from 0.14 mg/m3 to 0.07298 mg/m3 at least. In conclusion, the study on the critical point threshold of single environmental pollutant emission based on the modified grey clustering model has practical significance in the environmental fields, for example, environmental impact assessment, pollutant emission comprehensive control, decision making and etc.

Keywords: clustering model; comprehensive evaluation; critical point threshold; grey system; pollutant emission


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