提出了一种CLLC型模块化输入串联输出并联的直流变压器技术方案,实现了高压直流电网和低压直流电网之间的电压变换和功率的双向传输。直流变压器的子模块采用CLLC串联谐振变压器,通过开环定频控制模式和完全谐振工作模式,效率高、电压...提出了一种CLLC型模块化输入串联输出并联的直流变压器技术方案,实现了高压直流电网和低压直流电网之间的电压变换和功率的双向传输。直流变压器的子模块采用CLLC串联谐振变压器,通过开环定频控制模式和完全谐振工作模式,效率高、电压增益恒定,同时具有输入自然均压和输出自然均流的特点。为了抑制较大的启动冲击电流,提出了一种软启动控制策略:通过脉冲调制的方式控制输入端全桥电路的输出电压占空比D从Dmin缓慢增加到0.5。搭建了一台500 kW±7.5 k V/800 V直流变压器实验样机,实验结果验证了所提方案的正确性和可行性。展开更多
In frequency division duplex(FDD)massive multiple-input multiple-output(MIMO)systems,a bidirectional positional attention network(BPANet)was proposed to address the high computational complexity and low accuracy of ex...In frequency division duplex(FDD)massive multiple-input multiple-output(MIMO)systems,a bidirectional positional attention network(BPANet)was proposed to address the high computational complexity and low accuracy of existing deep learning-based channel state information(CSI)feedback methods.Specifically,a bidirectional position attention module(BPAM)was designed in the BPANet to improve the network performance.The BPAM captures the distribution characteristics of the CSI matrix by integrating channel and spatial dimension information,thereby enhancing the feature representation of the CSI matrix.Furthermore,channel attention is decomposed into two one-dimensional(1D)feature encoding processes effectively reducing computational costs.Simulation results demonstrate that,compared with the existing representative method complex input lightweight neural network(CLNet),BPANet reduces computational complexity by an average of 19.4%and improves accuracy by an average of 7.1%.Additionally,it performs better in terms of running time delay and cosine similarity.展开更多
A numerical approach is an effective means of solving boundary value problems(BVPs).This study focuses on physical problems with general partial differential equations(PDEs).It investigates the solution approach throu...A numerical approach is an effective means of solving boundary value problems(BVPs).This study focuses on physical problems with general partial differential equations(PDEs).It investigates the solution approach through the standard forms of the PDE module in COMSOL.Two typical mechanics problems are exemplified:The deflection of a thin plate,which can be addressed with the dedicated finite element module,and the stress of a pure bending beamthat cannot be tackled.The procedure for the two problems regarding the three standard forms required by the PDE module is detailed.The results were in good agreement with the literature,indicating that the PDE module provides a promising means to solve complex PDEs,especially for those a dedicated finite element module has yet to be developed.展开更多
文摘提出了一种CLLC型模块化输入串联输出并联的直流变压器技术方案,实现了高压直流电网和低压直流电网之间的电压变换和功率的双向传输。直流变压器的子模块采用CLLC串联谐振变压器,通过开环定频控制模式和完全谐振工作模式,效率高、电压增益恒定,同时具有输入自然均压和输出自然均流的特点。为了抑制较大的启动冲击电流,提出了一种软启动控制策略:通过脉冲调制的方式控制输入端全桥电路的输出电压占空比D从Dmin缓慢增加到0.5。搭建了一台500 kW±7.5 k V/800 V直流变压器实验样机,实验结果验证了所提方案的正确性和可行性。
基金supported by the National Natural Science Foundation of China(12005108)the Shandong Provincial Natural Science Foundation Youth Project(ZR2020QF016)the National Natural Science Foundation of China(U2006222)。
文摘In frequency division duplex(FDD)massive multiple-input multiple-output(MIMO)systems,a bidirectional positional attention network(BPANet)was proposed to address the high computational complexity and low accuracy of existing deep learning-based channel state information(CSI)feedback methods.Specifically,a bidirectional position attention module(BPAM)was designed in the BPANet to improve the network performance.The BPAM captures the distribution characteristics of the CSI matrix by integrating channel and spatial dimension information,thereby enhancing the feature representation of the CSI matrix.Furthermore,channel attention is decomposed into two one-dimensional(1D)feature encoding processes effectively reducing computational costs.Simulation results demonstrate that,compared with the existing representative method complex input lightweight neural network(CLNet),BPANet reduces computational complexity by an average of 19.4%and improves accuracy by an average of 7.1%.Additionally,it performs better in terms of running time delay and cosine similarity.
基金supported by the National Natural Science Foundations of China(Grant Nos.12372073 and U20B2013)the Natural Science Basic Research Program of Shaanxi(Program No.2023-JC-QN-0030).
文摘A numerical approach is an effective means of solving boundary value problems(BVPs).This study focuses on physical problems with general partial differential equations(PDEs).It investigates the solution approach through the standard forms of the PDE module in COMSOL.Two typical mechanics problems are exemplified:The deflection of a thin plate,which can be addressed with the dedicated finite element module,and the stress of a pure bending beamthat cannot be tackled.The procedure for the two problems regarding the three standard forms required by the PDE module is detailed.The results were in good agreement with the literature,indicating that the PDE module provides a promising means to solve complex PDEs,especially for those a dedicated finite element module has yet to be developed.
