摘要
为了建立一种能够预测柴油车道路排放特性的模型,文章采用便携式车载(汽车尾气)排放测量系统(portable emission measurement system, PEMS),对某重型柴油车进行道路污染物排放特性测试;利用测得的试验数据,在双隐含层反向传播(back propagation,BP)神经网络的基础上,引入Levenberg-Marquardt(LM)优化算法,用遗传算法(genetic algorithm,GA)优化网络的权值与阈值;以车辆比功率(vehicle specific power,VSP)为输入,搭建CO、NO_x排放预测模型,并用试验数据对模型进行训练、验证。结果表明,CO、NO_x的预测结果与样本数据之间的皮尔逊相关系数分别为0.855 3、0.851 2,线性高度相关;在整体误差水平上,CO、NO_x排放因子的相对误差分别为2.61%、6.71%。该方法对车辆CO、NO_x的瞬时排放和整体排放特性的预测准确性较好,具有一定的理论意义和工程应用价值。
In order to establish a model to predict the road emission characteristics of diesel vehicles, a portable emission measurement system(PEMS) is used to test the pollutant emission characteristics of a heavy duty diesel vehicle. Based on the experimental data of the double hidden layer back propagation(BP) neural network, the Levenberg-Marquardt(LM) optimization algorithm is introduced to build the prediction model of CO and NO_x emission with the input of the vehicle specific power(VSP). Genetic algorithm(GA) is used to optimize the network parameters of initial weights and thresholds and the model is trained and validated by the test data. The simulation results demonstrate good agreements between the raw data and the model predictions with Pearson correlation coefficients of 0.855 3 and 0.851 2 for CO and NO_x, respectively. And the relative error of the emission factor of CO and NO_x is 2.61% and 6.71%, respectively. The prediction accuracy of the instantaneous emission and the overall emission characteristics of the vehicle CO and NO_x is good, which shows that the method has certain theoretical significance and engineering application value.
引文
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