Routine reliability index method, first order second moment (FOSM), may not ensure convergence of iteration when the performance function is strongly nonlinear. A modified method was proposed to calculate reliability ...Routine reliability index method, first order second moment (FOSM), may not ensure convergence of iteration when the performance function is strongly nonlinear. A modified method was proposed to calculate reliability index based on maximum entropy (MaxEnt) principle. To achieve this goal, the complicated iteration of first order second moment (FOSM) method was replaced by the calculation of entropy density function. Local convergence of Newton iteration method utilized to calculate entropy density function was proved, which ensured the convergence of iteration when calculating reliability index. To promote calculation efficiency, Newton down-hill algorithm was incorporated into calculating entropy density function and Monte Carlo simulations (MCS) were performed to assess the efficiency of the presented method. Two numerical examples were presented to verify the validation of the presented method. Moreover, the execution and advantages of the presented method were explained. From Example 1, after seven times iteration, the proposed method is capable of calculating the reliability index when the performance function is strongly nonlinear and at the same time the proposed method can preserve the calculation accuracy; From Example 2, the reliability indices calculated using the proposed method, FOSM and MCS are 3.823 9, 3.813 0 and 3.827 6, respectively, and the according iteration times are 5, 36 and 10 6 , which shows that the presented method can improve calculation accuracy without increasing computational cost for the performance function of which the reliability index can be calculated using first order second moment (FOSM) method.展开更多
【目的】研究香料烟在云南的气候适生区,为其合理种植提供理论依据。【方法】使用ArcGIS将气候数据结合地形校正进行协同克里金插值,利用最大熵(maximum entropy,MaxEnt)模型筛选影响香料烟分布的气象因子,最后使用ArcGIS对云南省香料...【目的】研究香料烟在云南的气候适生区,为其合理种植提供理论依据。【方法】使用ArcGIS将气候数据结合地形校正进行协同克里金插值,利用最大熵(maximum entropy,MaxEnt)模型筛选影响香料烟分布的气象因子,最后使用ArcGIS对云南省香料烟的气候适生区进行评价。【结果】MaxEnt模型的曲线下面积(the area under curve,AUC)值为0.993,可精准预测云南省香料烟的气候适生区。影响香料烟在云南省分布的气象因子为2月降雨量、1月日照时间、3月日照时间、3月平均气温、3月降雨量、4月降雨量、1月降雨量、2月日照时间和4月最高气温。香料烟在云南省的最适宜种植区(四级适生区)主要分布在保山、德宏和临沧;适宜种植区(三级适生区)主要分布在保山、德宏、临沧、玉溪、楚雄和大理。MaxEnt模型预测结果与香料烟种植区拟合度较高,其种植区主要分布在四级和三级适生区,极少数分布在二级和一级适生区。【结论】云南省适合种植香料烟的地区主要在西南部,适宜种植区主要为沿怒江、澜沧江、黑惠江及其支流的干热河谷地区。2月降雨量、1月日照时间、3月日照时间和3月平均气温是影响香料烟在云南种植的主要气象因子。展开更多
为应对气候变化、推动绿色低碳转型,综合能源系统(integrated energy systems,IES)由此兴起并迅速发展。然而,异质能源载体间的耦合作用以及风光、负荷的随机波动给IES的规划运行带来新的挑战。为此,提出一种基于半不变量计算框架和最...为应对气候变化、推动绿色低碳转型,综合能源系统(integrated energy systems,IES)由此兴起并迅速发展。然而,异质能源载体间的耦合作用以及风光、负荷的随机波动给IES的规划运行带来新的挑战。为此,提出一种基于半不变量计算框架和最大熵原理的概率多能流求解方法,以充分反映计及不确定性因素下的电-气-热互联系统运行情况。首先对各能源载体以及耦合设备进行稳态建模并求解,获取多能耦合网络下状态变量的分布情况;其次,根据不确定性输入变量的概率特征,给出输出扰动状态变量的半不变量计算框架,联合最大熵模型求解输出状态变量的概率密度;然后,基于最大熵分布下的状态变量概率分布结果,识别异质能源系统下的薄弱节点;最后,采用IES 34-20-14与IES 57-20-32节点系统进行算例分析,并与多种状态变量分布的拟合方法对比。结果表明,所提方法能够保持在最大不确定性程度下获得准确的概率分布结果,实现对IES概率能流的快速求解。展开更多
基金Project(50978112) supported by the National Natural Science Foundation of China
文摘Routine reliability index method, first order second moment (FOSM), may not ensure convergence of iteration when the performance function is strongly nonlinear. A modified method was proposed to calculate reliability index based on maximum entropy (MaxEnt) principle. To achieve this goal, the complicated iteration of first order second moment (FOSM) method was replaced by the calculation of entropy density function. Local convergence of Newton iteration method utilized to calculate entropy density function was proved, which ensured the convergence of iteration when calculating reliability index. To promote calculation efficiency, Newton down-hill algorithm was incorporated into calculating entropy density function and Monte Carlo simulations (MCS) were performed to assess the efficiency of the presented method. Two numerical examples were presented to verify the validation of the presented method. Moreover, the execution and advantages of the presented method were explained. From Example 1, after seven times iteration, the proposed method is capable of calculating the reliability index when the performance function is strongly nonlinear and at the same time the proposed method can preserve the calculation accuracy; From Example 2, the reliability indices calculated using the proposed method, FOSM and MCS are 3.823 9, 3.813 0 and 3.827 6, respectively, and the according iteration times are 5, 36 and 10 6 , which shows that the presented method can improve calculation accuracy without increasing computational cost for the performance function of which the reliability index can be calculated using first order second moment (FOSM) method.
文摘【目的】研究香料烟在云南的气候适生区,为其合理种植提供理论依据。【方法】使用ArcGIS将气候数据结合地形校正进行协同克里金插值,利用最大熵(maximum entropy,MaxEnt)模型筛选影响香料烟分布的气象因子,最后使用ArcGIS对云南省香料烟的气候适生区进行评价。【结果】MaxEnt模型的曲线下面积(the area under curve,AUC)值为0.993,可精准预测云南省香料烟的气候适生区。影响香料烟在云南省分布的气象因子为2月降雨量、1月日照时间、3月日照时间、3月平均气温、3月降雨量、4月降雨量、1月降雨量、2月日照时间和4月最高气温。香料烟在云南省的最适宜种植区(四级适生区)主要分布在保山、德宏和临沧;适宜种植区(三级适生区)主要分布在保山、德宏、临沧、玉溪、楚雄和大理。MaxEnt模型预测结果与香料烟种植区拟合度较高,其种植区主要分布在四级和三级适生区,极少数分布在二级和一级适生区。【结论】云南省适合种植香料烟的地区主要在西南部,适宜种植区主要为沿怒江、澜沧江、黑惠江及其支流的干热河谷地区。2月降雨量、1月日照时间、3月日照时间和3月平均气温是影响香料烟在云南种植的主要气象因子。
文摘为应对气候变化、推动绿色低碳转型,综合能源系统(integrated energy systems,IES)由此兴起并迅速发展。然而,异质能源载体间的耦合作用以及风光、负荷的随机波动给IES的规划运行带来新的挑战。为此,提出一种基于半不变量计算框架和最大熵原理的概率多能流求解方法,以充分反映计及不确定性因素下的电-气-热互联系统运行情况。首先对各能源载体以及耦合设备进行稳态建模并求解,获取多能耦合网络下状态变量的分布情况;其次,根据不确定性输入变量的概率特征,给出输出扰动状态变量的半不变量计算框架,联合最大熵模型求解输出状态变量的概率密度;然后,基于最大熵分布下的状态变量概率分布结果,识别异质能源系统下的薄弱节点;最后,采用IES 34-20-14与IES 57-20-32节点系统进行算例分析,并与多种状态变量分布的拟合方法对比。结果表明,所提方法能够保持在最大不确定性程度下获得准确的概率分布结果,实现对IES概率能流的快速求解。
