Surrogate models have shown to be effective in assisting evolutionary algorithms(EAs)for solving computationally expensive complex optimization problems.However,the effectiveness of the existing surrogate-assisted evo...Surrogate models have shown to be effective in assisting evolutionary algorithms(EAs)for solving computationally expensive complex optimization problems.However,the effectiveness of the existing surrogate-assisted evolutionary algorithms still needs to be improved.A data-driven evolutionary sampling optimization(DESO)framework is proposed,where at each generation it randomly employs one of two evolutionary sampling strategies,surrogate screening and surrogate local search based on historical data,to effectively balance global and local search.In DESO,the radial basis function(RBF)is used as the surrogate model in the sampling strategy,and different degrees of the evolutionary process are used to sample candidate points.The sampled points by sampling strategies are evaluated,and then added into the database for the updating surrogate model and population in the next sampling.To get the insight of DESO,extensive experiments and analysis of DESO have been performed.The proposed algorithm presents superior computational efficiency and robustness compared with five state-of-the-art algorithms on benchmark problems from 20 to 200 dimensions.Besides,DESO is applied to an airfoil design problem to show its effectiveness.展开更多
针对经典MCMC(Markov chain Monte Carlo)算法求解河流水污染源信息(排放量、排放时间和排放位置)时初始点的选取和接受率不高导致的计算效率低下问题,通过COMSOL仿真软件构建污染物二维扩散模型,利用不同算法对比分析了上述两方面对水...针对经典MCMC(Markov chain Monte Carlo)算法求解河流水污染源信息(排放量、排放时间和排放位置)时初始点的选取和接受率不高导致的计算效率低下问题,通过COMSOL仿真软件构建污染物二维扩散模型,利用不同算法对比分析了上述两方面对水污染溯源结果的影响,并由此提出了基于等距随机抽样方法(equidistant random sampling)的两阶段多链Metropolis Hastings算法(ERS-TSMH).仿真结果表明,传统的MH算法和TSMH算法在求解时易陷入局部最优值或不收敛的情况,前者接受率在20%左右,后者却达到近50%;多链ERS-MH算法提高了反演的准确性,但经过10 000次左右迭代后收敛,效率低下;多链ERS-TSMH算法在保证溯源精度的同时,在5 000次左右迭代后收敛,效率显著提高且表现出高稳定性和可靠性.展开更多
处于改建阶段的智能变电站采样模式复杂,继电保护装置难以发现采样回路轻微异常,导致回路隐患暴露时间严重滞后。针对上述问题,分析改建时期智能变电站的采样模式和二次设备配置情况,提出基于同源录波数据比对的继电保护采样回路异常检...处于改建阶段的智能变电站采样模式复杂,继电保护装置难以发现采样回路轻微异常,导致回路隐患暴露时间严重滞后。针对上述问题,分析改建时期智能变电站的采样模式和二次设备配置情况,提出基于同源录波数据比对的继电保护采样回路异常检测方法。首先,利用双向编码器表征(bidirectional encoder representations from transformers,BERT)语言模型与余弦相似度算法,实现同源录波数据的通道匹配。然后,利用重采样技术和曼哈顿距离完成波形的采样频率统一与时域对齐。最后,基于动态时间规整(dynamic time warping,DTW)算法提出改进算法,并结合采样点偏移量共同设置采样回路的异常判据。算例分析表明,该方法可以完成录波数据的同源通道匹配,实现波形的一致性对齐,并且相比于传统DTW算法,改进DTW算法对异常状态识别的灵敏性和准确性更高。根据异常判据能够有效检测继电保护采样回路的异常状态,确保了智能变电站的安全可靠运行。展开更多
针对RRT(rapidly exploring random tree)路径规划算法搜索范围大、目标导向差、容易陷入局部最小值以及路径曲折等问题,提出了一种限制自适应采样区域的改进RRT路径规划算法。将整个搜索空间划分成均匀的等级,根据新节点所在等级和该...针对RRT(rapidly exploring random tree)路径规划算法搜索范围大、目标导向差、容易陷入局部最小值以及路径曲折等问题,提出了一种限制自适应采样区域的改进RRT路径规划算法。将整个搜索空间划分成均匀的等级,根据新节点所在等级和该等级内采样点数量动态调整采样区域,减小搜索范围;利用新节点改进策略使随机树根据环境信息自适应地向目标点调整,并改变扩展步长生成新节点;利用障碍物躲避策略提高算法的目标导向性和躲避障碍物的性能;利用改进的逆向寻优和插入节点并减小转向角的三次B样条曲线对路径进行优化处理。该算法在不同的路径环境中相较于RRT算法的搜索时间和迭代次数均减少了70%以上,且经过优化的路径更短、更平滑。展开更多
基金supported by the National Natural Science Foundation of China(62076225,62073300)the Natural Science Foundation for Distinguished Young Scholars of Hubei(2019CFA081)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(CUGGC03).
文摘Surrogate models have shown to be effective in assisting evolutionary algorithms(EAs)for solving computationally expensive complex optimization problems.However,the effectiveness of the existing surrogate-assisted evolutionary algorithms still needs to be improved.A data-driven evolutionary sampling optimization(DESO)framework is proposed,where at each generation it randomly employs one of two evolutionary sampling strategies,surrogate screening and surrogate local search based on historical data,to effectively balance global and local search.In DESO,the radial basis function(RBF)is used as the surrogate model in the sampling strategy,and different degrees of the evolutionary process are used to sample candidate points.The sampled points by sampling strategies are evaluated,and then added into the database for the updating surrogate model and population in the next sampling.To get the insight of DESO,extensive experiments and analysis of DESO have been performed.The proposed algorithm presents superior computational efficiency and robustness compared with five state-of-the-art algorithms on benchmark problems from 20 to 200 dimensions.Besides,DESO is applied to an airfoil design problem to show its effectiveness.
文摘针对经典MCMC(Markov chain Monte Carlo)算法求解河流水污染源信息(排放量、排放时间和排放位置)时初始点的选取和接受率不高导致的计算效率低下问题,通过COMSOL仿真软件构建污染物二维扩散模型,利用不同算法对比分析了上述两方面对水污染溯源结果的影响,并由此提出了基于等距随机抽样方法(equidistant random sampling)的两阶段多链Metropolis Hastings算法(ERS-TSMH).仿真结果表明,传统的MH算法和TSMH算法在求解时易陷入局部最优值或不收敛的情况,前者接受率在20%左右,后者却达到近50%;多链ERS-MH算法提高了反演的准确性,但经过10 000次左右迭代后收敛,效率低下;多链ERS-TSMH算法在保证溯源精度的同时,在5 000次左右迭代后收敛,效率显著提高且表现出高稳定性和可靠性.
文摘处于改建阶段的智能变电站采样模式复杂,继电保护装置难以发现采样回路轻微异常,导致回路隐患暴露时间严重滞后。针对上述问题,分析改建时期智能变电站的采样模式和二次设备配置情况,提出基于同源录波数据比对的继电保护采样回路异常检测方法。首先,利用双向编码器表征(bidirectional encoder representations from transformers,BERT)语言模型与余弦相似度算法,实现同源录波数据的通道匹配。然后,利用重采样技术和曼哈顿距离完成波形的采样频率统一与时域对齐。最后,基于动态时间规整(dynamic time warping,DTW)算法提出改进算法,并结合采样点偏移量共同设置采样回路的异常判据。算例分析表明,该方法可以完成录波数据的同源通道匹配,实现波形的一致性对齐,并且相比于传统DTW算法,改进DTW算法对异常状态识别的灵敏性和准确性更高。根据异常判据能够有效检测继电保护采样回路的异常状态,确保了智能变电站的安全可靠运行。
文摘针对RRT(rapidly exploring random tree)路径规划算法搜索范围大、目标导向差、容易陷入局部最小值以及路径曲折等问题,提出了一种限制自适应采样区域的改进RRT路径规划算法。将整个搜索空间划分成均匀的等级,根据新节点所在等级和该等级内采样点数量动态调整采样区域,减小搜索范围;利用新节点改进策略使随机树根据环境信息自适应地向目标点调整,并改变扩展步长生成新节点;利用障碍物躲避策略提高算法的目标导向性和躲避障碍物的性能;利用改进的逆向寻优和插入节点并减小转向角的三次B样条曲线对路径进行优化处理。该算法在不同的路径环境中相较于RRT算法的搜索时间和迭代次数均减少了70%以上,且经过优化的路径更短、更平滑。
