基于投影寻踪和阶梯型曲线的水质恢复能力评价模型

利用投影寻踪、遗传算法、阶梯型曲线和水体水质恢复能力评价标准,为水体水质恢复能力综合评价提出了一种新的方法--遗传投影寻踪方法(GPPM).GPPM可把水体水质恢复能力多维评价样本指标综合成一维投影指标值.根据该投影指标值的大小就可以对该样本集进行统一评价,从而解决了各单项水体水质恢复能力评价指标评价结果的不相容问题,提高了水体水质恢复能力综合评价问题各层次的分辩力.文中给出了GPPM实施的详细步骤,并在各等级中分别产生建模样本50个、100个、500个、1 000个、1 500个和2 000个,对评价模型参数的稳定性进行了检验,结果表明所建模型是稳定的.根据黄河干流三类主要污染物BOD、氨氮和挥发酚的浓度对黄河干流的水质恢复能力进行了评价,发现整体上黄河干流的水质恢复能力较弱.GPPM不仅可以对水体水质恢复能力进行综合评价,还可以确定评价指标的权重.GPPM可广泛应用于各种水质综合评价问题中.

Assessment model of water quality recoverability based on genetic projection pursuit and ladder shape curve

The given article aims to establish a high precision assessment model as well as to provide a case study on water quality recoverability. Since the study in this area is still at the beginning stage in China, people's idea on water quality recoverability remains very poor. To solve the incompatibility of assessment indexes of water quality recoverability and heighten the precision of the due assessment, it is suggested to use a genetic projection method (GPPM) for comprehensive assessment of water quality recoverability by means of projection pursuing, genetic algorithm, a ladder shape curve and the corresponding assessment standards in this way. In so doing, the indexes of water quality recoverability samples can be synthesized by the projection indexes in one dimension. Then, the samples can be naturally tested according to the projection indexes, so as to develop a detailed step for GPPM. That is to say, 50, 100, 500, 1000, 1500, 2000 samples in each grade could be taken to test the stability of parameters in the model. The testing result shows that the parameters gained are steady. When the method was used to assess the water quality recoverability with the mainstream of the Yellow River, three main pollutant concentrations were taken into account, including BOD, NH_4~+-N and volatile phenol. The results show that the water quality recoverability is rather weak in the mainstream of the Yellow River on the whole. However, GPPM has been proved a method with such features as direct, convenient and efficient in application. It can also be used to determine the weight of the index system. Thus, the assessment method can be said superior in assessing various water quality recoverability problems.