提出一种识别影响电力系统电压稳定关键节点的关键注入区域新算法。计算系统各节点的电压稳定指标,确定系统电压稳定关键节点。以电压稳定关键节点为关键注入区域的主导节点,借助相关增益矩阵的相关性质,识别与系统中各电压稳定主导节...提出一种识别影响电力系统电压稳定关键节点的关键注入区域新算法。计算系统各节点的电压稳定指标,确定系统电压稳定关键节点。以电压稳定关键节点为关键注入区域的主导节点,借助相关增益矩阵的相关性质,识别与系统中各电压稳定主导节点存在强电压耦合关系的负荷节点和发电机节点,构建含电压稳定主导节点的电压稳定关键注入区域;针对所得注入区域,给出系统稳态和紧急情况下改善系统电压稳定性的相关控制策略。将所提方法应用于New England 39节点系统中,分析、对比结果验证了所提方法的正确性和有效性。最后将该方法应用于波兰电网中,验证了该方法的实用性。展开更多
To realize efficient and sustainable poverty alleviation,this study firstly investigated the identification of multidimensional poverty and relative poverty,and then explored relevant poverty alleviation pathways.Pove...To realize efficient and sustainable poverty alleviation,this study firstly investigated the identification of multidimensional poverty and relative poverty,and then explored relevant poverty alleviation pathways.Poverty levels in 31 provinces including the autonomous regions and municipalities of China were identified at the county level using the average nighttime light index(ANLI),county multidimensional development index(CMDI),and a method combining multidimensional poverty index and relative poverty standards.Poverty alleviation pathways for poverty-stricken counties were explored from the aspects of industry,education,tourism and agriculture.The results revealed that nearly 60% of counties in China were primarily under relative poverty,most of which were corresponded to light relative poverty.In terms of ANLI and CMDI,63% and 79% of the national poverty-stricken counties,as of 2018,could be identified,suggesting that CMDI had a higher performance for identifying poverty at the county level.In terms of poverty alleviation pathways,414,172,442,and 298 poverty-stricken counties were receptive to industry poverty alleviation,education poverty alleviation,tourism poverty alleviation,and agriculture poverty alleviation,and 61%of counties had more poverty-causing factors,implying that multidimensional poverty alleviation is suitable in most of the counties.展开更多
Hopf bifurcation and chaos of a nonlinear electromechanical coupling relative rotation system are studied in this paper. Considering the energy in air-gap field of AC motor, the dynamical equation of nonlinear electro...Hopf bifurcation and chaos of a nonlinear electromechanical coupling relative rotation system are studied in this paper. Considering the energy in air-gap field of AC motor, the dynamical equation of nonlinear electromechanical coupling relative rotation system is deduced by using the dissipation Lagrange equation. Choosing the electromagnetic stiffness as a bifurcation parameter, the necessary and sufficient conditions of Hopf bifurcation are given, and the bifurcation characteristics are studied. The mechanism and conditions of system parameters for chaotic motions are investigated rigorously based on the Silnikov method, and the homoclinic orbit is found by using the undetermined coefficient method. Therefore, Smale horseshoe chaos occurs when electromagnetic stiffness changes. Numerical simulations are also given, which confirm the analytical results.展开更多
The Hückel’s rule,Baird’s rule,and electronic shell closure model are classical and well-established concepts in chemistry,which have long been employed in rationalizing the aromaticity/antiaromaticity of organ...The Hückel’s rule,Baird’s rule,and electronic shell closure model are classical and well-established concepts in chemistry,which have long been employed in rationalizing the aromaticity/antiaromaticity of organic species and stability of inorganic clusters.Thus,the observation of unique species featuring properties out of the fundamental frameworks of these rules is challenging but significant and helps in drawing a complete picture of fascinating concepts in chemistry.展开更多
机器设备的同步控制是运动控制领域的热点研究内容,同步精度对加工质量等要素存在显著影响,但易受扰动影响。针对多电机同步控制精度易受外部扰动等因素影响,提出了一种基于优化同步误差补偿方法的偏差耦合算法。引入增益方程对同步误...机器设备的同步控制是运动控制领域的热点研究内容,同步精度对加工质量等要素存在显著影响,但易受扰动影响。针对多电机同步控制精度易受外部扰动等因素影响,提出了一种基于优化同步误差补偿方法的偏差耦合算法。引入增益方程对同步误差补偿值进行动态调节,并应用基于改进交叉和变异算子的自适应遗传算法(Adaptive Genetic Algorithm Based on Improved Crossover and Mutation Operator, ECIM-AGA)对方程中的增益系数取值进行寻优。通过建立4台电机的仿真实验,与传统偏差耦合算法相比,结果表明,所提方法的超调量σ分别降低了29.26%、4.19%、2.77%和33.99%,全局同步误差分别下降了40.27%、11.70%、29.74%和28.04%,具有更佳的同步精度。展开更多
文摘提出一种识别影响电力系统电压稳定关键节点的关键注入区域新算法。计算系统各节点的电压稳定指标,确定系统电压稳定关键节点。以电压稳定关键节点为关键注入区域的主导节点,借助相关增益矩阵的相关性质,识别与系统中各电压稳定主导节点存在强电压耦合关系的负荷节点和发电机节点,构建含电压稳定主导节点的电压稳定关键注入区域;针对所得注入区域,给出系统稳态和紧急情况下改善系统电压稳定性的相关控制策略。将所提方法应用于New England 39节点系统中,分析、对比结果验证了所提方法的正确性和有效性。最后将该方法应用于波兰电网中,验证了该方法的实用性。
基金Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDA23070400National Natural Science Foundation of China,No.41901234,No.51909052。
文摘To realize efficient and sustainable poverty alleviation,this study firstly investigated the identification of multidimensional poverty and relative poverty,and then explored relevant poverty alleviation pathways.Poverty levels in 31 provinces including the autonomous regions and municipalities of China were identified at the county level using the average nighttime light index(ANLI),county multidimensional development index(CMDI),and a method combining multidimensional poverty index and relative poverty standards.Poverty alleviation pathways for poverty-stricken counties were explored from the aspects of industry,education,tourism and agriculture.The results revealed that nearly 60% of counties in China were primarily under relative poverty,most of which were corresponded to light relative poverty.In terms of ANLI and CMDI,63% and 79% of the national poverty-stricken counties,as of 2018,could be identified,suggesting that CMDI had a higher performance for identifying poverty at the county level.In terms of poverty alleviation pathways,414,172,442,and 298 poverty-stricken counties were receptive to industry poverty alleviation,education poverty alleviation,tourism poverty alleviation,and agriculture poverty alleviation,and 61%of counties had more poverty-causing factors,implying that multidimensional poverty alleviation is suitable in most of the counties.
基金supported by the National Natural Science Foundation of China(Grant No.61104040)the Natural Science Foundation of Hebei Province,China(Grant No.E2012203090)
文摘Hopf bifurcation and chaos of a nonlinear electromechanical coupling relative rotation system are studied in this paper. Considering the energy in air-gap field of AC motor, the dynamical equation of nonlinear electromechanical coupling relative rotation system is deduced by using the dissipation Lagrange equation. Choosing the electromagnetic stiffness as a bifurcation parameter, the necessary and sufficient conditions of Hopf bifurcation are given, and the bifurcation characteristics are studied. The mechanism and conditions of system parameters for chaotic motions are investigated rigorously based on the Silnikov method, and the homoclinic orbit is found by using the undetermined coefficient method. Therefore, Smale horseshoe chaos occurs when electromagnetic stiffness changes. Numerical simulations are also given, which confirm the analytical results.
基金supported by the Taishan Scholars Project of Shandong Province(no.ts201712011)the National Natural Science Foundation of China(NSFC)(nos.21603119 and 21705093)+4 种基金the Natural Science Foundation of Shandong Province(nos.ZR2017BB061 and ZR2016BQ09)the Natural Science Foundation of Jiangsu Province(no.BK20170396)the Project for Scientific Research Innovation Team of Young Scholar in Colleges and Universities of Shandong Province(no.2019KJC025)the Young Scholars Program of Shandong University(YSPSDU)(no.2018WLJH48)the Qilu Youth Scholar Funding of Shandong University,and the Fundamental Research Funds of Shandong University(no.2017TB003).
文摘The Hückel’s rule,Baird’s rule,and electronic shell closure model are classical and well-established concepts in chemistry,which have long been employed in rationalizing the aromaticity/antiaromaticity of organic species and stability of inorganic clusters.Thus,the observation of unique species featuring properties out of the fundamental frameworks of these rules is challenging but significant and helps in drawing a complete picture of fascinating concepts in chemistry.
文摘机器设备的同步控制是运动控制领域的热点研究内容,同步精度对加工质量等要素存在显著影响,但易受扰动影响。针对多电机同步控制精度易受外部扰动等因素影响,提出了一种基于优化同步误差补偿方法的偏差耦合算法。引入增益方程对同步误差补偿值进行动态调节,并应用基于改进交叉和变异算子的自适应遗传算法(Adaptive Genetic Algorithm Based on Improved Crossover and Mutation Operator, ECIM-AGA)对方程中的增益系数取值进行寻优。通过建立4台电机的仿真实验,与传统偏差耦合算法相比,结果表明,所提方法的超调量σ分别降低了29.26%、4.19%、2.77%和33.99%,全局同步误差分别下降了40.27%、11.70%、29.74%和28.04%,具有更佳的同步精度。
