Intelligent Segmentation Method of Inland Waterway for Energy Efficiency Optimization
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摘要: 内河航道航段的自动科学划分对提升船舶能效模型的精度具有重要意义。针对船舶能效优化过程中,根据航段划分结果构建的各航段油耗预测模型和航速预测模型精度不高等问题,研究了1种基于能效优化的内河航道智能划分方法。该方法通过归一化处理以及构建通航环境参数与船舶能效的相关性系数将通航环境参数对船舶能效的影响程度纳入到通航环境数据聚类中,运用K-means聚类算法将整条航线划分为多段;运用随机森林(random forest,RF)算法建立各航段的船舶油耗预测模型和船舶航速预测模型;通过优化聚类数量实现船舶能效模型综合平均绝对百分比误差(mean absolute percentage error,MAPE)最低。以1艘内河散货船为研究对象,对该方法进行实例应用和验证,并分析了数据量对船舶能效模型综合精度的影响。研究结果表明:通过优化聚类数量可以实现船舶能效模型综合精度的提升,采用该方法构建第1航次的油耗预测模型和航速预测模型,实现船舶能效模型综合MAPE由3.53%降低至3.32%;增加构建船舶能效模型的能效相关数据的数据量有利于船舶能效模型综合精度的提升,当对象船舶用于建模的能效数据由1个航次增加到5个航次时,船舶能效模型综合MAPE由3.32%降低至1.65%;不同建模数据的最佳聚类数量不同,通过取多航次的综合最佳聚类数可实现航道的优化划分;所提出航道划分方法得到的能效模型综合MAPE比常用航道划分方法得到的能效模型综合MAPE降低了0.54%,验证了所提出的航道划分方法对提升船舶能效预测模型精度的有效性。
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关键词:
- 能效优化 /
- 内河船舶 /
- 航段划分 /
- K-means聚类算法
Abstract: The automatic scientific segmentation of inland waterways is significant to enhancing the accuracy of ship energy efficiency models. To address the problem of low accuracy in fuel consumption and speed prediction models built based on conventional waterway segmentation for energy efficiency optimization, an intelligent segmentation method of inland waterways aimed at optimizing energy efficiency is studied. The method incorporates the influence of navigational environmental parameters on ship energy performance into the clustering process by normalizing the data and calculating correlation coefficients between environmental parameters and energy efficiency indicators. The K-means clustering algorithm is employed to segment the entire route into multiple sections. For each segment, Random Forest algorithm is used to establish models for fuel consumption and ship speed prediction. The optimal number of clusters is determined by minimizing the overall mean absolute percentage error (MAPE) of the energy efficiency models. A case study involving an inland bulk carrier is conducted to demonstrate the application and validate the effectiveness of the proposed method, along with an analysis of the influence of data volume on the model accuracy. The results show that optimizing the number of clusters significantly improves model accuracy: in the firstly voyage, the comprehensive MAPE of the energy efficiency model is reduced from 3.53% to 3.32%. Increasing the volume of energy-related data used in model construction further enhances the performance: when the dataset expanded from one voyage to five, the comprehensive MAPE decreased from 3.32% to 1.65%. The optimal number of clusters varies with different datasets, and selecting an optimal number of clusters based on multi-voyage data leads to the optimal waterway segmentation. Compared to the conventional segmentation method, the proposed approach reduced the comprehensive MAPE of energy efficiency model by 0.54%, validating the effectiveness of the method in improving the prediction accuracy of ship energy efficiency model. -
表 1 对象船舶主要参数
Table 1. Main parameters of the target ship
参数 数值 船长/m 99.8 型宽/m 16.2 型深/m 5.8 主机功率/kw 2×850 吃水/m 4.9 排水量/t 6 949.4 表 2 通航环境与能效之间的相关系数
Table 2. Correlation coefficients between navigational environment and energy efficiency
能效参数 通航环境 风速 风向 水深 水流速度 油耗 0.023 0.034 -0.346 -0.275 航速 0.33 -0.271 0.029 0.741 表 3 预处理后的部分通航环境数据
Table 3. Partial avigational environment data after preprocessing
风速 风向 水深 水流速度 0.062 5 -0.032 1 -0.014 1 0.146 5 0.059 8 -0.039 6 -0.014 8 0.147 6 0.055 6 -0.105 3 -0.013 9 0.146 9 0.040 3 -0.105 3 -0.086 4 0.127 1 0.043 1 -0.037 3 -0.085 5 0.135 3 ⋮ ⋮ ⋮ ⋮ 表 4 RF算法的超参数设置
Table 4. Hyperparameter settings for RF algorithm
模型 超参数类型 不同航次参数值 第1航次 第1~2航次 第1~3航次 第1~4航次 第1~5航次 油耗预测模型 n_estimators 104 92 94 118 180 max_depth 22 24 25 26 25 min_samples_leaf 2 4 2 3 4 min_samples_split 2 6 14 14 6 max_leaf_nodes 3 382 3 979 3 743 3 752 3 990 航速预测模型 n_estimators 104 110 113 116 175 max_depth 19 23 23 26 26 min_samples_leaf 1 3 3 3 3 min_samples_split 12 3 14 5 15 max_leaf_nodes 3 758 3 990 3 972 3 944 3 995 表 5 划分方法对能效模型精度的影响
Table 5. The impact of segment division methods on the accuracy of energy efficiency models
划分方法 最佳聚类数量n 油耗预测模型MAPE/% 油耗预测模型MAPE/% 能效模型综合MAPE/% 常用方法 5 2.14 2.23 2.19 本文方法 10 1.58 1.72 1.65 -
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