由于电力市场的发展和智能电网技术的推广,负荷预测变得越来越重要。准确的预测结果有助于提高电力系统运行效率,降低运行成本,减少＂电荒＂事件的发生。在当前海量高维数据的背景下,有效并准确的在线预测方法是当下的研究重点。针对传...由于电力市场的发展和智能电网技术的推广,负荷预测变得越来越重要。准确的预测结果有助于提高电力系统运行效率,降低运行成本,减少＂电荒＂事件的发生。在当前海量高维数据的背景下,有效并准确的在线预测方法是当下的研究重点。针对传统预测方法对新增数据需要重复训练造成的巨大计算消耗和模型利用率低的缺点,提出了一种基于在线序列极限支持向量回归算法（online sequential extreme support vector regression,OS-ESVR）的短期负荷预测模型（short-term load forecasting,STLF）。首先,利用基于随机森林模型的递归特征消除方法（recursive feature elimination based on random forest,RF-RFE）自动选择滞后负荷输入变量;其次,将得出的有效数据信息输入到在线序列支持向量回归模型进行训练学习,训练过程中通过简化粒子群算法（simplified particle swarm optimization,SPSO）对初始模型进行优化,得到训练后的在线序列支持向量回归模型;最后,利用测试数据测试模型。通过在新英格兰ISO（Independent System Operator）数据集进行仿真算例分析,验证了模型能够根据新增数据动态更新。同时预测结果表明了所提模型的时效性和准确性显著优于已有的同类方法。展开更多
The noise-induced transition of the augmented Lotka-Volterra system is investigated under vanishingly small noise.Populations will ultimately go extinct because of intrinsic noise,and different extinction routes may o...The noise-induced transition of the augmented Lotka-Volterra system is investigated under vanishingly small noise.Populations will ultimately go extinct because of intrinsic noise,and different extinction routes may occur due to the Freidlin-Wentzell large deviation theory.The relation between the most probable extinction route(MPER)and heteroclinic bifurcation is studied in this paper.The MPERs and the quasi-potentials in different regimes of parameters are analyzed in detail.Before the bifurcation,the predator goes extinct,and the prey will survive for a long time.Then,the heteroclinic bifurcation changes the MPER wherein both species go extinct.The heteroclinic cycle plays a role in transferring the most probable extinction state.Moreover,the analyses of the weak noise limit can contribute to predicting the stochastic behavior under finite small noise.Both the heteroclinic bifurcation and the rotational deterministic vector field can reduce the action necessary for the MPER.展开更多
The authors first establish a quantum microscopic scattering matrix model in multidimen-sional wave-vector space, which relates the phase space density of each superlattice cell withthat of the neighbouring cells. The...The authors first establish a quantum microscopic scattering matrix model in multidimen-sional wave-vector space, which relates the phase space density of each superlattice cell withthat of the neighbouring cells. Then, in the limit of a large number of cells, a SHE (SphericalHarmonics Expansion)-type model of diffusion equations for the particle number density in theposition-energy space is obtained. The crucial features of diffusion constants on retaining thememory of the quantum scattering characteristics of the superlattice elementary cell (like e.g.transmission resonances) are shown in order. Two examples are treated with the analyticallycomputation of the diffusion constants.展开更多
文摘由于电力市场的发展和智能电网技术的推广,负荷预测变得越来越重要。准确的预测结果有助于提高电力系统运行效率,降低运行成本,减少＂电荒＂事件的发生。在当前海量高维数据的背景下,有效并准确的在线预测方法是当下的研究重点。针对传统预测方法对新增数据需要重复训练造成的巨大计算消耗和模型利用率低的缺点,提出了一种基于在线序列极限支持向量回归算法（online sequential extreme support vector regression,OS-ESVR）的短期负荷预测模型（short-term load forecasting,STLF）。首先,利用基于随机森林模型的递归特征消除方法（recursive feature elimination based on random forest,RF-RFE）自动选择滞后负荷输入变量;其次,将得出的有效数据信息输入到在线序列支持向量回归模型进行训练学习,训练过程中通过简化粒子群算法（simplified particle swarm optimization,SPSO）对初始模型进行优化,得到训练后的在线序列支持向量回归模型;最后,利用测试数据测试模型。通过在新英格兰ISO（Independent System Operator）数据集进行仿真算例分析,验证了模型能够根据新增数据动态更新。同时预测结果表明了所提模型的时效性和准确性显著优于已有的同类方法。
基金the National Natural Science Foundation of China(Grant Nos.11772149,and 12172167)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education In-stitutions(PAPD)and The Research Fund of State Key Laboratory of Me-chanics and Control of Mechanical Structures(Grant No.MCMS-I-19G0l).
文摘The noise-induced transition of the augmented Lotka-Volterra system is investigated under vanishingly small noise.Populations will ultimately go extinct because of intrinsic noise,and different extinction routes may occur due to the Freidlin-Wentzell large deviation theory.The relation between the most probable extinction route(MPER)and heteroclinic bifurcation is studied in this paper.The MPERs and the quasi-potentials in different regimes of parameters are analyzed in detail.Before the bifurcation,the predator goes extinct,and the prey will survive for a long time.Then,the heteroclinic bifurcation changes the MPER wherein both species go extinct.The heteroclinic cycle plays a role in transferring the most probable extinction state.Moreover,the analyses of the weak noise limit can contribute to predicting the stochastic behavior under finite small noise.Both the heteroclinic bifurcation and the rotational deterministic vector field can reduce the action necessary for the MPER.
基金Project supported by the TMR network No.ERB FMBX CT97 0157 on‘Asymptotic methods in kinetic theory'of the European Community,the LIAMA(Laboratoire d'Informatique,Automatique et Mathematiques Appliquees),the PRA(Programme de Recherches Avancees),the Aust
文摘The authors first establish a quantum microscopic scattering matrix model in multidimen-sional wave-vector space, which relates the phase space density of each superlattice cell withthat of the neighbouring cells. Then, in the limit of a large number of cells, a SHE (SphericalHarmonics Expansion)-type model of diffusion equations for the particle number density in theposition-energy space is obtained. The crucial features of diffusion constants on retaining thememory of the quantum scattering characteristics of the superlattice elementary cell (like e.g.transmission resonances) are shown in order. Two examples are treated with the analyticallycomputation of the diffusion constants.
