Journal of Environmental Hydrology
ISSN 1058-3912
Electronic journal of the International Association for Environmental
Hydrology
On the World Wide Web at http://www.hydroweb.com
JEH VOLUME 5 (1997) PAPER 2
A GREY SYSTEM MODEL FOR PREDICTING TREND CHANGE OF URBAN WASTE WATER
LOAD
Xia Jun and Hu Baoqing
Institute of Hydrology and Water Environmental Science
Wuhan University of Hydraulic and Electric Engineering, China
ABSTRACT
The present paper introduces a Grey System Prediction Model (GSPM)
by incorporating concepts of grey numbers within a grey differential equation
framework as a means for predicting trends in urban waste water load under
uncertainty. A new operation law of grey numbers was developed that overcomes
some of disadvantages of present interval operations. In the light of these
operation principles, the original grey differential equation can be reduced
to two equivalent sub-models. One is whitening or averaged value system
equation that is equivalent to the GM(1,1) prediction model in grey system
theory. Another is a grey radius equation, expressing system uncertainty.
The GSPM approach improves upon previous prediction models by allowing
uncertainty information to be directly communicated into the grey series
modeling and prediction. The method also does not lead to more complicated
models, and is applicable to practical problems. The GSPM approach has
been applied to trend change prediction of waste water load in Luo Yang
City, He Nan Province, China. Preliminary examinations indicate that reasonable
solutions can be generated. Besides trend change information, the grey
system model could provide the degree of uncertainty of model parameters
and output variables.
Reference: Xia, J. and B. Hu; A Grey System Model
for Predicting Trend Change of Urban Waste Water Load, Journal of Environmental
Hydrology, Vol. 5, Paper 2, 1997.
CONTACT:
Professor Xia Jun
Faculty of Hydrology
Department of River Engineering
Wuhan University of Hydraulic and Electric Engineering
Wuhan 430072 China
E-mail: jxia@sun20.wuhee.edu.cn
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