This paper presents a rotating parallel-plate capacitor;one of the plates is assumed to turn about the common vertical axis through the centers of the square plates. Viewing the problem from a purely geometrical point...This paper presents a rotating parallel-plate capacitor;one of the plates is assumed to turn about the common vertical axis through the centers of the square plates. Viewing the problem from a purely geometrical point of view, we evaluate the overlapping area of the plates as a function of the rotated angle. We then envision the rotation as being a mechanical continuous process. We consider two different rotation mechanisms: a uniform rotation with a constant angular velocity and, a rotation with a constant angular acceleration—we then evaluate the overlapping area as a continuous function of time. From the electrostatic point of view, the time-dependent overlapping area of the plates implies a time-dependent capacitor. Such a variable, a time-dependent capacitor has never been reported in literature. We insert this capacitor into a series with a resistor, forming a RC circuit. We analyze the characteristics of charging and discharging scenarios on two different parallel tracks. On the first track we drive the circuit with a DC power sup-ply. We study the implications of the rotation modes. We compare the response of each case to the corresponding tradi-tional constant capacitor of an equivalent RC circuit;the quantified results are intuitively just. On the second track, we drive the circuit with an AC source. Similar to the analysis of the first track, we generate the relevant electrical characteristics. In the latter case, we also analyze the sensitivity of the response of the circuit with respect to the fre-quency of the source. The analyses of the circuits encounter nontrivial differential equations. We utilize Mathematica [1] to solve these equations.展开更多
Urban water supply network is a modern urban survival and development of the infrastructure of a city,and its normal running conditions have important significance. The actual hydraulic process in the variableload wat...Urban water supply network is a modern urban survival and development of the infrastructure of a city,and its normal running conditions have important significance. The actual hydraulic process in the variableload water distribution networks can be treated as the slow transient flow which belongs to the unsteady flow. This paper analyzes the multi-loops network slow transient model based on graph theory,and the link flow matrix is treated as the variables of the discrete solution model to simulate the process of the slow transient flow in the network. With the simulation of hydraulic regime in an actual pipe network,the changing laws of the flow in the pipes,nodal hydraulic heads and other hydraulic factors with the passage of time are obtained. Since the transient processes offer much more information than a steady process,the slow transient theory is not only practical on analyzing the hydraulic condition of the network,but also on identifying hydraulic resistance coefficients of pipes and detecting the leakage in networks.展开更多
A new type of ANN (Artificial Neural Network) structure is introduced, and a nonlinear transformation of the original features is proposed so as to improve the learning covergence of the neural network. This kind of i...A new type of ANN (Artificial Neural Network) structure is introduced, and a nonlinear transformation of the original features is proposed so as to improve the learning covergence of the neural network. This kind of improved ANN is then used to analyse the transient stability of two real power systems. The results show that this method possesses better effectiveness and high convergence speed.展开更多
A transient delay-coupled network was proposed by modifying the standard delay-coupled network with a transient coupling technique to enlarge the synchronization domain of the network, where the synchronization domain...A transient delay-coupled network was proposed by modifying the standard delay-coupled network with a transient coupling technique to enlarge the synchronization domain of the network, where the synchronization domain is the interval of the coupling strength for which the network gets synchronized. The coupling of the transient delay-coupled network is activated when the systems are in a particular region (coupling region) of the phase space and inactivated otherwise, which is different from the standard coupling. The specific synchronization performance of the transient delay-coupled network was investigated through case studies. The relationships between the synchronization domain and the coupling region were obtained by gauging the synchronization index. It is understood that the synchronization domain changes in a non-smooth manner with the variation of the coupling region. In particular, the synchronization domain of a transient delay-coupled network is much larger than that of the standard delay-coupled network when the coupling region is appropriately determined.展开更多
By establishing concept an transient solutions of general nonlinear systems converging to its equilibrium set, long-time behavior of solutions for cellular neural network systems is studied. A stability condition in g...By establishing concept an transient solutions of general nonlinear systems converging to its equilibrium set, long-time behavior of solutions for cellular neural network systems is studied. A stability condition in generalized sense is obtained. This result reported has an important guide to concrete neural network designs.展开更多
现代电力系统海量量测数据为电力系统暂态稳定评估提供可靠的数据基础,与此同时,数据信息挖掘成为研究焦点,暂态稳定分析中不平衡故障样本以及多特征电气量时间序列数据中所蕴藏的信息仍有待深入挖掘。为此,该文提出一种结合注意力机制...现代电力系统海量量测数据为电力系统暂态稳定评估提供可靠的数据基础,与此同时,数据信息挖掘成为研究焦点,暂态稳定分析中不平衡故障样本以及多特征电气量时间序列数据中所蕴藏的信息仍有待深入挖掘。为此,该文提出一种结合注意力机制的长短期记忆网络(long short term memory network with attention,LSTMA)方法,用以深入挖掘暂态稳定评估样本中所蕴藏的信息。在离线训练环节,以长短期记忆网络为基础分类器,引入Attention注意力机制引导模型学习样本中关键特征,并对损失函数进行改进,以此强化对不平衡样本的学习能力;在线应用环节,在目标域小样本条件下采用迁移学习方法更新成型的离线LSTMA模型,并对比不同迁移学习策略对模型性能影响,经过迁移学习建立的新运行点下的改进LSTMA模型评估精度有效提高,训练时间大幅减少,所得出的迁移学习策略确定方法有利于实际应用环节快速决策。研究在IEEE39节点和IEEE300节点系统上进行实验,验证了所提方法的有效性。展开更多
文摘This paper presents a rotating parallel-plate capacitor;one of the plates is assumed to turn about the common vertical axis through the centers of the square plates. Viewing the problem from a purely geometrical point of view, we evaluate the overlapping area of the plates as a function of the rotated angle. We then envision the rotation as being a mechanical continuous process. We consider two different rotation mechanisms: a uniform rotation with a constant angular velocity and, a rotation with a constant angular acceleration—we then evaluate the overlapping area as a continuous function of time. From the electrostatic point of view, the time-dependent overlapping area of the plates implies a time-dependent capacitor. Such a variable, a time-dependent capacitor has never been reported in literature. We insert this capacitor into a series with a resistor, forming a RC circuit. We analyze the characteristics of charging and discharging scenarios on two different parallel tracks. On the first track we drive the circuit with a DC power sup-ply. We study the implications of the rotation modes. We compare the response of each case to the corresponding tradi-tional constant capacitor of an equivalent RC circuit;the quantified results are intuitively just. On the second track, we drive the circuit with an AC source. Similar to the analysis of the first track, we generate the relevant electrical characteristics. In the latter case, we also analyze the sensitivity of the response of the circuit with respect to the fre-quency of the source. The analyses of the circuits encounter nontrivial differential equations. We utilize Mathematica [1] to solve these equations.
基金Sponsored by the National Natural Science Foundation of China(Grant No.50908064 and 51208158)the 46thChina Postdoctoral Science Foundation(Grant No.20090460912)
文摘Urban water supply network is a modern urban survival and development of the infrastructure of a city,and its normal running conditions have important significance. The actual hydraulic process in the variableload water distribution networks can be treated as the slow transient flow which belongs to the unsteady flow. This paper analyzes the multi-loops network slow transient model based on graph theory,and the link flow matrix is treated as the variables of the discrete solution model to simulate the process of the slow transient flow in the network. With the simulation of hydraulic regime in an actual pipe network,the changing laws of the flow in the pipes,nodal hydraulic heads and other hydraulic factors with the passage of time are obtained. Since the transient processes offer much more information than a steady process,the slow transient theory is not only practical on analyzing the hydraulic condition of the network,but also on identifying hydraulic resistance coefficients of pipes and detecting the leakage in networks.
文摘A new type of ANN (Artificial Neural Network) structure is introduced, and a nonlinear transformation of the original features is proposed so as to improve the learning covergence of the neural network. This kind of improved ANN is then used to analyse the transient stability of two real power systems. The results show that this method possesses better effectiveness and high convergence speed.
文摘A transient delay-coupled network was proposed by modifying the standard delay-coupled network with a transient coupling technique to enlarge the synchronization domain of the network, where the synchronization domain is the interval of the coupling strength for which the network gets synchronized. The coupling of the transient delay-coupled network is activated when the systems are in a particular region (coupling region) of the phase space and inactivated otherwise, which is different from the standard coupling. The specific synchronization performance of the transient delay-coupled network was investigated through case studies. The relationships between the synchronization domain and the coupling region were obtained by gauging the synchronization index. It is understood that the synchronization domain changes in a non-smooth manner with the variation of the coupling region. In particular, the synchronization domain of a transient delay-coupled network is much larger than that of the standard delay-coupled network when the coupling region is appropriately determined.
文摘By establishing concept an transient solutions of general nonlinear systems converging to its equilibrium set, long-time behavior of solutions for cellular neural network systems is studied. A stability condition in generalized sense is obtained. This result reported has an important guide to concrete neural network designs.
文摘现代电力系统海量量测数据为电力系统暂态稳定评估提供可靠的数据基础,与此同时,数据信息挖掘成为研究焦点,暂态稳定分析中不平衡故障样本以及多特征电气量时间序列数据中所蕴藏的信息仍有待深入挖掘。为此,该文提出一种结合注意力机制的长短期记忆网络(long short term memory network with attention,LSTMA)方法,用以深入挖掘暂态稳定评估样本中所蕴藏的信息。在离线训练环节,以长短期记忆网络为基础分类器,引入Attention注意力机制引导模型学习样本中关键特征,并对损失函数进行改进,以此强化对不平衡样本的学习能力;在线应用环节,在目标域小样本条件下采用迁移学习方法更新成型的离线LSTMA模型,并对比不同迁移学习策略对模型性能影响,经过迁移学习建立的新运行点下的改进LSTMA模型评估精度有效提高,训练时间大幅减少,所得出的迁移学习策略确定方法有利于实际应用环节快速决策。研究在IEEE39节点和IEEE300节点系统上进行实验,验证了所提方法的有效性。
