The low-frequency oscillation(LFO)has occurred in the train-network system due to the introduction of the power electronics of the trains.The modeling and analyzing method in current researches based on electrified ra...The low-frequency oscillation(LFO)has occurred in the train-network system due to the introduction of the power electronics of the trains.The modeling and analyzing method in current researches based on electrified railway unilateral power supply system are not suitable for the LFO analysis in a bilateral power supply system,where the trains are supplied by two traction substations.In this work,based on the single-input and single-output impedance model of China CRH5 trains,the node admittance matrices of the train-network system both in unilateral and bilateral power supply modes are established,including three-phase power grid,traction transformers and traction network.Then the modal analysis is used to study the oscillation modes and propagation characteristics of the unilateral and bilateral power supply systems.Moreover,the influence of the equivalent inductance of the power grid,the length of the transmission line,and the length of the traction network are analyzed on the critical oscillation mode of the bilateral power supply system.Finally,the theoretical analysis results are verified by the time-domain simulation model in MATLAB/Simulink.展开更多
混合专家模型(mixture of experts,MoE)是一种神经网络模型架构,其特点是在模型中引入路由网络与专家子网络,进而代替原始的稠密网络。在推理过程中,MoE架构通过路由网络选择每次需要激活的专家子网络,仅激活其中部分专家完成给定任务...混合专家模型(mixture of experts,MoE)是一种神经网络模型架构,其特点是在模型中引入路由网络与专家子网络,进而代替原始的稠密网络。在推理过程中,MoE架构通过路由网络选择每次需要激活的专家子网络,仅激活其中部分专家完成给定任务。由于采用稀疏激活机制,混合专家模型同与其性能相当的稠密模型相比,大幅减少了训练和推理过程的计算开销,使得在给定计算成本下扩展模型规模成为可能。展开更多
Power electronic traction transformers(PETTs)will be increasingly applied to locomotives in the future for their small volume and light weight.However,similar to conventional trains,PETTs behave as constant power load...Power electronic traction transformers(PETTs)will be increasingly applied to locomotives in the future for their small volume and light weight.However,similar to conventional trains,PETTs behave as constant power loads and may cause low-frequency oscillation(LFO)to the train-network system.To solve this issue,a mathematical model of the PETT is firstly proposed and verified based on the extended describing function(EDF)method in this paper.In the proposed model,the LLC converter is simplified to an equivalent circuit consisting of a capacitor and a resistor in parallel.It is further demonstrated that the model can apply to various LLC converters with different topologies and controls.Particularly,when the parameter differences between cells are not obvious,the PETT can be simplified to a single-phase rectifier(i.e.,conventional train)by equivalent transformation.Based on the model of PETT,the system low-frequency stability and influential factors are analyzed by using the generalized Nyquist criterion.Lastly,the correctness and accuracy of theoretical analyses are validated by off-line and hardware-in-the-loop simulation results.展开更多
情感分类是自然语言处理领域的热点研究问题之一,方面级的文本情感分类旨在识别文本不同方面间的情感极性。针对方面级情感分类模型存在特征提取能力弱、方面词与上下文间交互不充分的问题,提出基于交互对抗网络的方面级情感分类模型(As...情感分类是自然语言处理领域的热点研究问题之一,方面级的文本情感分类旨在识别文本不同方面间的情感极性。针对方面级情感分类模型存在特征提取能力弱、方面词与上下文间交互不充分的问题,提出基于交互对抗网络的方面级情感分类模型(Aspect-level Sentiment classification model based on Interactive Adversarial Networks,ASIAN)。首先,通过Transformer的双向表征编码器模型作为编码器,将方面词和上下文进行单独建模提取隐含层特征。其次,构建交互注意力网络,将隐含层特征进行交互学习。最后,对交互信息进行联合学习,做交叉熵损失、回传参数。此外,ASIAN添加了对抗训练旨在进一步优化分类效果。在SemEval-2014任务4中的Laptop、Restaurant数据集和ACL-2014的Twitter数据集上,ASIAN与大多数基线模型相比有较高的分类准确率。展开更多
基金This work was supported by the Applied Basic Research Program of Science and Technology Plan Project of Sichuan Province of China(No.2020YJ0252).
文摘The low-frequency oscillation(LFO)has occurred in the train-network system due to the introduction of the power electronics of the trains.The modeling and analyzing method in current researches based on electrified railway unilateral power supply system are not suitable for the LFO analysis in a bilateral power supply system,where the trains are supplied by two traction substations.In this work,based on the single-input and single-output impedance model of China CRH5 trains,the node admittance matrices of the train-network system both in unilateral and bilateral power supply modes are established,including three-phase power grid,traction transformers and traction network.Then the modal analysis is used to study the oscillation modes and propagation characteristics of the unilateral and bilateral power supply systems.Moreover,the influence of the equivalent inductance of the power grid,the length of the transmission line,and the length of the traction network are analyzed on the critical oscillation mode of the bilateral power supply system.Finally,the theoretical analysis results are verified by the time-domain simulation model in MATLAB/Simulink.
文摘混合专家模型(mixture of experts,MoE)是一种神经网络模型架构,其特点是在模型中引入路由网络与专家子网络,进而代替原始的稠密网络。在推理过程中,MoE架构通过路由网络选择每次需要激活的专家子网络,仅激活其中部分专家完成给定任务。由于采用稀疏激活机制,混合专家模型同与其性能相当的稠密模型相比,大幅减少了训练和推理过程的计算开销,使得在给定计算成本下扩展模型规模成为可能。
基金supported in part by the National Natural Science Foundation of China(52125705)in part by the Natural Science Foundation of Hunan Province(2022JJ40066)。
文摘Power electronic traction transformers(PETTs)will be increasingly applied to locomotives in the future for their small volume and light weight.However,similar to conventional trains,PETTs behave as constant power loads and may cause low-frequency oscillation(LFO)to the train-network system.To solve this issue,a mathematical model of the PETT is firstly proposed and verified based on the extended describing function(EDF)method in this paper.In the proposed model,the LLC converter is simplified to an equivalent circuit consisting of a capacitor and a resistor in parallel.It is further demonstrated that the model can apply to various LLC converters with different topologies and controls.Particularly,when the parameter differences between cells are not obvious,the PETT can be simplified to a single-phase rectifier(i.e.,conventional train)by equivalent transformation.Based on the model of PETT,the system low-frequency stability and influential factors are analyzed by using the generalized Nyquist criterion.Lastly,the correctness and accuracy of theoretical analyses are validated by off-line and hardware-in-the-loop simulation results.
文摘情感分类是自然语言处理领域的热点研究问题之一,方面级的文本情感分类旨在识别文本不同方面间的情感极性。针对方面级情感分类模型存在特征提取能力弱、方面词与上下文间交互不充分的问题,提出基于交互对抗网络的方面级情感分类模型(Aspect-level Sentiment classification model based on Interactive Adversarial Networks,ASIAN)。首先,通过Transformer的双向表征编码器模型作为编码器,将方面词和上下文进行单独建模提取隐含层特征。其次,构建交互注意力网络,将隐含层特征进行交互学习。最后,对交互信息进行联合学习,做交叉熵损失、回传参数。此外,ASIAN添加了对抗训练旨在进一步优化分类效果。在SemEval-2014任务4中的Laptop、Restaurant数据集和ACL-2014的Twitter数据集上,ASIAN与大多数基线模型相比有较高的分类准确率。
