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Research on Phase-Shifted Full-Bridge Circuit Based on Frequency and Phase-Shift Synthesis Modulation Strategy
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作者 Mingda Jiang Yanbo Che +2 位作者 Hongfeng Li Muhammad Ishaq Chao Xing 《Energy Engineering》 EI 2022年第2期699-721,共23页
The full-bridge converters usually use transformer leakage inductance and parallel resonant capacitors to achieve smooth current commutation and soft switching functions,which can easily cause problems such as energy ... The full-bridge converters usually use transformer leakage inductance and parallel resonant capacitors to achieve smooth current commutation and soft switching functions,which can easily cause problems such as energy leakage and significant duty cycle loss.This paper designs a novel full-bridge zero-current(FB-ZCS)converter with series resonant capacitors and proposes a frequency and phase-shift synthesis modulation(FPSSM)control strategy based on this topology.Compared with the traditional parallel resonant capacitor circuit,the passive components used are significantly reduced,the structure is simple,and there is only a slight energy loss.By controlling the charging time of the capacitor,it can be achieved without additional switches or auxiliary circuits.The automatic control of capacitor energy based on input current addresses the low efficiency of the traditional control strategies.This paper introduces its principle in detail and verifies it through simulation.Finally,an experimental prototype was built further to demonstrate the feasibility of the theory through experiments.The module can be applied to a photovoltaic DC collection system using input parallel output series(IPOS)cascade to provide a new topology for large-scale,long-distance DC transmission. 展开更多
关键词 Full-bridge converter frequency and phase-shift synthesis modulation(FPSSM) photovoltaic DC collection system control strategy
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Drifting Modulation Instability:Periodization of General Breathers,Asymmetric Sideband Modulation,and IST Spectral Portrait
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作者 Ming-Hao Ma Xiaotian Xu +1 位作者 Chong Liu Wen-Li Yang 《Chinese Physics Letters》 2026年第4期7-13,共7页
study drifting modulation instability(MI)that exhibits asymmetric discrete spectrum recurrences in the nonlinear stage within the framework of the focusing nonlinear Schr¨odinger equation.We demonstrate that such... study drifting modulation instability(MI)that exhibits asymmetric discrete spectrum recurrences in the nonlinear stage within the framework of the focusing nonlinear Schr¨odinger equation.We demonstrate that such drifting MI can arise either from the local periodization of general breathers or from numerical simulations starting with an initial modulation containing asymmetric sidebands. 展开更多
关键词 initial modulation containing asymmetric sidebands local periodization numerical simulations general breathers drifting modulation instability asymmetric sideband modulation asymmetric discrete spectrum recurrences spectral portrait
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Tunable frequency-multiplying optoelectronic oscillator based on a dual-parallel Mach-Zehnder modulator incorporating a phase-shifted fiber Bragg grating 被引量:2
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作者 ZHANG Yao NING Ti-gang +4 位作者 LI Jing ZHENG Jing-jing LIU Ling DONG Xiao-wei PEI Li 《Optoelectronics Letters》 EI 2020年第6期405-409,共5页
A tunable frequency-multiplying optoelectronic oscillator(OEO) based on a dual-parallel Mach-Zehnder modulator(DPMZM) is proposed and experimentally demonstrated. In the proposed system, the tunable fundamental microw... A tunable frequency-multiplying optoelectronic oscillator(OEO) based on a dual-parallel Mach-Zehnder modulator(DPMZM) is proposed and experimentally demonstrated. In the proposed system, the tunable fundamental microware signal is generated by a tunable optoelectronic oscillator incorporating a phase-shifted fiber Bragg grating(PS-FBG). By adjusting the DC bias of the DPMZM, the frequency-doubled microwave signal with a tunable frequency range from 11 GHz to 20 GHz and the frequency-quadrupled microwave signal with a tunable frequency range from 22.5 GHz to 26 GHz are generated. The phase noises of the fundamental, frequency-doubled and frequency-quadrupled signals at 10 k Hz offset frequency are-105.9 d Bc/Hz,-103.3 d Bc/Hz and-86.2 d Bc/Hz, respectively. 展开更多
关键词 MZM FBG Tunable frequency-multiplying optoelectronic oscillator based on a dual-parallel Mach-Zehnder modulator incorporating a phase-shifted fiber Bragg grating Bragg
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Opto-mechanical-thermal integration analysis of Doppler asymmetric spatial heterodyne interferometer 被引量:1
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作者 WANG Jin-jiang JIANG Lun +3 位作者 TONG Shou-feng PEI Hui-yi CUI Yong GUO Ming-hang 《中国光学(中英文)》 EI CAS CSCD 北大核心 2024年第6期1489-1511,共23页
In order to improve the detection accuracy of Doppler asymmetric spatial heterodyne(DASH)interferometer in harsh temperatures,an opto-mechanical-thermal integration analysis is carried out.Firstly,the correlation betw... In order to improve the detection accuracy of Doppler asymmetric spatial heterodyne(DASH)interferometer in harsh temperatures,an opto-mechanical-thermal integration analysis is carried out.Firstly,the correlation between the interference phase and temperature is established according to the working principle and the phase algorithm of the interferometer.Secondly,the optical mechanical thermal analysis model and thermal deformation data acquisition model are designed.The deformation data of the interference module and the imaging optical system at different temperatures are given by temperature load simulation analysis,and the phase error caused by thermal deformation is obtained by fitting.Finally,based on the wind speed error caused by thermal deformation of each component,a reasonable temperature control scheme is proposed.The results show that the interference module occupies the main cause,the temperature must be controlled within(20±0.05)℃,and the temperature control should be carried out for the temperature sensitive parts,and the wind speed error caused by the part is 3.8 m/s.The thermal drift between the magnification of the imaging optical system and the thermal drift of the relative position between the imaging optical system and the detector should occupy the secondary cause,which should be controlled within(20±2)℃,and the wind speed error caused by the part is 3.05 m/s.In summary,the wind measurement error caused by interference module,imaging optical system,and the relative position between the imaging optical system and the detector can be controlled within 6.85 m/s.The analysis and temperature control schemes presented in this paper can provide theoretical basis for DASH interferometer engineering applications. 展开更多
关键词 Doppler asymmetric spatial heterodyne interferometer interference module imaging optical system opto-mechanical thermal integration analysis phase error temperature control
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A Single-Board Integrated Millimeter-Wave Asymmetric Full-Digital Beamforming Array for B5G/6G Applications 被引量:1
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作者 Qingqing Lin Jun Xu +9 位作者 Kai Chen Long Wang Wei Li Zhiqiang Yu Guangqi Yang Jianyi Zhou Zhe Chen Jixin Chen Xiaowei Zhu Wei Hong 《Engineering》 SCIE EI CAS CSCD 2024年第10期35-50,共16页
In this article,a single-board integrated millimeter-wave(mm-Wave)asymmetric full-digital beamforming(AFDBF)array is developed for beyond-fifth-generation(B5G)and sixth-generation(6G)communications.The proposed integr... In this article,a single-board integrated millimeter-wave(mm-Wave)asymmetric full-digital beamforming(AFDBF)array is developed for beyond-fifth-generation(B5G)and sixth-generation(6G)communications.The proposed integrated array effectively addresses the challenge of arranging a large number of ports in a full-digital array by designing vertical connections in a three-dimensional space and successfully integrating full-digital transmitting(Tx)and receiving(Rx)arrays independently in a single board.Unlike the traditional symmetric array,the proposed asymmetric array is composed of an 8×8 Tx array arranged in a square shape and an 8+8 Rx array arranged in an L shape.The center-to-center distance between two adjacent elements is 0.54k0 for both the Tx and Rx arrays,where k0 is the free-space wavelength at 27 GHz.The proposed AFDBF array possesses a more compact structure and lower system hardware cost and power consumption compared with conventional brick-type full-digital arrays.In addition,the energy efficiency of the proposed AFDBF array outperforms that of a hybrid beamforming array.The measurement results indicate that the operating frequency band of the proposed array is 24.25–29.50 GHz.An eight-element linear array within the Tx array can achieve a scanning angle ranging from-47°to+47°in both the azimuth and the elevation planes,and the measured scanning range of each eight-element Rx array is–45°to+45°.The measured maximum effective isotropic radiated power(EIRP)of the eight-element Tx array is 43.2 dBm at 28.0 GHz(considering the saturation point).Furthermore,the measured error vector magnitude(EVM)is less than 3%when 64-quadrature amplitude modulation(QAM)waveforms are used. 展开更多
关键词 Full-digital beamforming array asymmetric structure Single-board integrated Beyond fifth-generation and sixthgeneration Millimeter-wave communication Complex modulation Printed circuit board Vertical connection
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An Electroabsorption Modulator Monolithically Integrated with a Semiconductor Optical Amplifier and a Dual-Waveguide Spot-Size Converter
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作者 侯廉平 王圩 +3 位作者 朱洪亮 周帆 王鲁峰 边静 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2005年第8期1504-1508,共5页
A semiconductor optical amplifier and electroabsorption modulator monolithically integrated with a spotsize converter input and output is fabricated by means of selective area growth,quantum well intermixing,and asymm... A semiconductor optical amplifier and electroabsorption modulator monolithically integrated with a spotsize converter input and output is fabricated by means of selective area growth,quantum well intermixing,and asymmetric twin waveguide technology. A 1550-1600nm lossless operation with a high DC extinction ratio of 25dB and more than 10GHz 3dB bandwidth are successfully achieved. The output beam divergence angles of the device in the horizontal and vertical directions are as small as 7.3°× 18.0°, respectively, resulting in a 3.0dB coupling loss with a cleaved single-mode optical fiber. 展开更多
关键词 semiconductor optical amplifier electroabsorption modulator spot-size converters selective area growth quantum well intermixing asymmetric twin waveguide
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基于三相Buck整流器直流链电流纹波特性的最优三段式不对称空间矢量脉宽调制技术
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作者 陈欣 谢飞 许建平 《电工技术学报》 北大核心 2026年第3期738-748,共11页
三段式不对称空间矢量脉宽调制(SVPWM)可以有效地抑制三相Buck整流器扇区切换引起的不规则直流链电流纹波,从而降低输入电流总谐波畸变率(THD)。根据矢量作用顺序的不同,可组成多种不对称脉宽调制(PWM)序列,通常认为它们具有等效的矢量... 三段式不对称空间矢量脉宽调制(SVPWM)可以有效地抑制三相Buck整流器扇区切换引起的不规则直流链电流纹波,从而降低输入电流总谐波畸变率(THD)。根据矢量作用顺序的不同,可组成多种不对称脉宽调制(PWM)序列,通常认为它们具有等效的矢量合成效果。然而,在相同输入条件、不同的不对称PWM序列的直流链电流纹波特性存在显著差异,进而影响输入电流THD。该文分析了两种不对称PWM调制序列的直流链电流纹波特性,得出对应不同输入电压相序的最优不对称PWM序列。通过相序自适应调制策略,对随机接入的输入电压相序均可实现低直流链电流纹波和低输入电流THD,有效解决了不对称调制的不对称性带来的电流畸变问题。最后设计了一台1 kW的实验样机,验证了理论分析的正确性。 展开更多
关键词 三相Buck整流器 不对称调制 直流链电流纹波 输入电流畸变 输入相序
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面向固态变压器应用的非对称双有源桥直流变换器
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作者 冯顶宽 高宁 +1 位作者 马建军 朱淼 《电工技术学报》 北大核心 2026年第4期1324-1339,共16页
面向固态变压器应用,该文提出一种非对称双向有源桥(ABAB,简记为AB2)直流变换器拓扑。该拓扑采用有源全桥与半有源桥并联而成,可实现正反向差异化电能传输,同时提升器件复用率以降低成本。首先,分析AB2变换器功率传输特性,提出基于统一... 面向固态变压器应用,该文提出一种非对称双向有源桥(ABAB,简记为AB2)直流变换器拓扑。该拓扑采用有源全桥与半有源桥并联而成,可实现正反向差异化电能传输,同时提升器件复用率以降低成本。首先,分析AB2变换器功率传输特性,提出基于统一移相占空比的双模式调制策略,当正向传输功率时,以双半有源桥模式运行;反之,则以双有源桥模式运行。该调制策略可实现模式间平滑切换,兼具功率环流抑制与宽范围零电压软开关优势。在此基础上,给出电路参数设计方法和控制策略,面向某车网互动充电站应用,基于AB2变换器等三种典型直流变换器拓扑展开系统设计、方案对比和仿真验证。最后,搭建额定功率为140 W(正向)/60 W(反向)的AB2变换器原理样机,其峰值效率为96.53%(正向)/96.19%(反向),仿真与实验结果验证了所提拓扑的可行性及其在电流应力、损耗、成本及可靠性方面的优势。 展开更多
关键词 固态变压器 非对称双向有源桥直流变换器 双模式调制 软开关运行
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结合注意力机制的轻量化网络高光谱图像分类
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作者 张迎豪 杨芳 《哈尔滨工业大学学报》 北大核心 2026年第3期151-163,共13页
高光谱图像分类是遥感领域的核心难题,其挑战主要源于高光谱图像的光谱维度高、空间分辨率低,导致分类任务中难以充分提取高光谱图像的空谱特征。针对现有的卷积神经网络(CNN)高光谱图像分类模型参数量大、计算资源消耗高、分类精度不... 高光谱图像分类是遥感领域的核心难题,其挑战主要源于高光谱图像的光谱维度高、空间分辨率低,导致分类任务中难以充分提取高光谱图像的空谱特征。针对现有的卷积神经网络(CNN)高光谱图像分类模型参数量大、计算资源消耗高、分类精度不足的问题,提出了一种基于注意力机制的轻量化网络高光谱图像分类模型(AMLW-CNN)。为了增强网络的特征提取能力,将空谱特征提取模块设计为2个多尺度提取模块,并将空间特征提取模块的各卷积层通过残差结构连接,同时引入注意力机制来强化网络对有效特征的提取。另外,为了减少模型参数量,采用非对称卷积来替代三维卷积核、深度可分离卷积来替换二维卷积核。实验结果表明:AMLW-CNN的分类精度优于对比算法,计算复杂度更低,鲁棒性更强。在Indian Pines、Salinas和Pavia U 3个数据集上的总体分类精度分别达到了98.5%、99.8%、99.9%。 展开更多
关键词 高光谱图像分类 多尺度提取模块 注意力机制 轻量化网络 非对称卷积 深度可分离卷积
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Tailoring surface charge distribution via lattice Cl-doping on Cu_(2)O nanocubes for high-selectivity CO_(2)-to-C^(2+)electroreduction via asymmetric C–C coupling
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作者 Kai Kang Qiuxiang Wang +6 位作者 Hongpu Huang Xinxin Zhuang Junlin Cai Tao Wang Xue Wang Zhaoxiong Xie Shuifen Xie 《Science China Chemistry》 2026年第1期217-224,共8页
Despite utilization of state-of-the-art Cu-based catalysts,achieving high selectivity and stability in multicarbon(C^(2+))compounds production through electrocatalytic CO_(2)reduction reaction(CO_(2)RR)remains a criti... Despite utilization of state-of-the-art Cu-based catalysts,achieving high selectivity and stability in multicarbon(C^(2+))compounds production through electrocatalytic CO_(2)reduction reaction(CO_(2)RR)remains a critical and challenging objective.Here we employ lattice chlorine-doped Cu_(2)O nanocubes(Cl_(d)-Cu_(2)O NCs)with well-defined{100}facets as a model catalyst to demonstrate that halogen doping can serve as a versatile and effective strategy for modulating surface charge distribution,thereby enhancing asymmetric C-C coupling toward high-selectivity C^(2+)products in CO_(2)RR.Compared to Cl-free Cu_(2)O NCs,Cl_(d)-Cu_(2)O NCs exhibit a greatly enhanced C^(2+)Faraday efficiency,i.e.,~85%at-1.1 V(versus the reversible hydrogen electrode).Additionally,the Cl_(d)-Cu_(2)O NCs demonstrate significantly enhanced long-term durability,attributed to better preservation of the cubic morphology and more stable Cu^(δ+)states.In-situ electrochemical studies reveal that Cl_(d)-Cu_(2)O NCs facilitate the formation of the key asymmetric*COH and*OCCOH intermediates,ultimately leading to higher C^(2+)products.Density functional theory(DFT)calculations confirm that the introduced Cl-dopants disrupt the charge balance of the Cu_(2)O(100)surface,enriching the Cl-adjacent Cu atoms with more electrons compared to those near O atoms.This unbalanced charge distribution significantly reduces the free energy of the rate-determining step for asymmetric C-C coupling from the*CO to*OCCOH on Cl-doped Cu_(2)O(100)surface,requiring only 1.04 e V,in contrast to 1.50 e V on pristine Cu_(2)O(100)surface.This study provides valuable insights into the surface charge modulation of Cu_(2)O catalysts via halogen doping for enhancing asymmetric C-C coupling and C^(2+)production in CO_(2)RR. 展开更多
关键词 surface charge modulation lattice halogen doping Cu_(2)O nanocubes CO_(2)-to-C^(2+)electrocatalysis asymmetric C-C coupling
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Three-step self-calibrating generalized phase-shifting interferometry
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作者 Yu Zhang 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第3期234-240,共7页
An accurate and fast three-step self-calibrating generalized phase-shifting interferomertry(SGPSI) is proposed. In this approach, two new phase-shifting signals are constructed by the difference interferograms normali... An accurate and fast three-step self-calibrating generalized phase-shifting interferomertry(SGPSI) is proposed. In this approach, two new phase-shifting signals are constructed by the difference interferograms normalization and noise suppressing, then the unknown phase shift between the two difference phase-shifting signals is estimated quickly through searching the minimum coefficient of variation of the modulation amplitude, a limited number of pixels are selected to participate in the search process to further save time, and finally the phase is reconstructed through the searched phase shift. Through the reconstruction of phase map by the simulation and experiment, and the comparison with several mature algorithms, the good performance of the proposed algorithm is proved, and it eliminates the limitation of requiring more than three phase-shifting interferograms for high-precision SGPSI. We expect this method to be widely used in the future. 展开更多
关键词 self-calibrating generalized phase-shifting interferomertry phase shift difference interferograms modulation amplitude
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基于MDL-U2-Net的盆底超声图像轻量级分割及参数测量
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作者 刘孝保 甘博敏 +1 位作者 姚廷强 申吉泓 《计算机辅助设计与图形学学报》 北大核心 2025年第2期277-292,共16页
准确地分割超声图像中盆底区域,是实现盆底疾病计算机辅助诊断的重要环节.针对盆底形态复杂、边界模糊、分割算法参数量庞大以及参数测量精度有限等问题,搭建了一种轻量级语义分割网络MDL-U2-Net并提出修补算法AC-F.首先,对基准U2-Net... 准确地分割超声图像中盆底区域,是实现盆底疾病计算机辅助诊断的重要环节.针对盆底形态复杂、边界模糊、分割算法参数量庞大以及参数测量精度有限等问题,搭建了一种轻量级语义分割网络MDL-U2-Net并提出修补算法AC-F.首先,对基准U2-Net进行结构优化和通道数调整,以有效地降低模型参数量;其次,融入复合损失函数以缓解训练损失波动并提升边界保持能力,提高网络对模糊边界的分割准确性;之后,提出深度非对称多尺度混洗卷积模块,以捕获特征空间采样的位置偏移信息,弥补轻量网络感受野不足和特征提取能力较弱的缺陷,提高网络对盆底复杂形态的建模能力;最后,采用修补算法对分割盆底进行精细化填补,以提高盆底完整性和参数测量的精度.在自制数据集上的实验结果表明,MDL-U2-Net对盆底分割的Jaccard,Recall和HD95指标分别达到91.226%,93.589%和1.074,与基准U2-Net相比,模型参数量缩减了94.37个百分点;此外,经AC-F算法处理后的区域面积测量百分误差降至1.25%,ICC达到0.998且有95%(76/80)的数据在95%LoA内,能够实现轻量级分割和精确参数测量. 展开更多
关键词 盆底超声图像 轻量化 复合损失函数 深度非对称通道混洗卷积模块 参数测量
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基于双向WPT系统非对称调制策略研究与应用 被引量:1
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作者 周梦豪 王付胜 +1 位作者 杨金涛 唐立 《中国电机工程学报》 北大核心 2025年第13期5213-5225,I0024,共14页
为了提高双向LCC-LCC型无线电能传输系统在轻载工况时的传输效率,提出一种适用于全功率范围的非对称调制策略,该调制策略可随输出功率的变化自动实现全桥模式到半桥模式的平滑过渡,且可实现宽范围软开关,进而显著提高系统效率。通过对... 为了提高双向LCC-LCC型无线电能传输系统在轻载工况时的传输效率,提出一种适用于全功率范围的非对称调制策略,该调制策略可随输出功率的变化自动实现全桥模式到半桥模式的平滑过渡,且可实现宽范围软开关,进而显著提高系统效率。通过对系统效率进行定量分析,建立非对称调制策略脉宽优化的理论基础;在此基础上,对非对称调制策略的所有工作模式进行详细划分,并引入时域模型,定量分析不同工作模式下实现软开关的约束条件;最后,通过搭建实验平台对不同工况下所提非对称调制策略和三移相调制策略进行对比实验和分析,证明所提调制策略的可行性和有效性。 展开更多
关键词 LCC-LCC 双向无线电能传输 非对称调制 脉宽优化 软开关
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基于改进的DeepLabv3+模型的自然环境下舌象分割方法 被引量:1
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作者 刘嵘澂 辛国江 +1 位作者 张杨 朱磊 《计算机与现代化》 2025年第10期32-36,43,共6页
在自然环境下采集的舌象图像,受光照、背景等因素的影响,其精确分割具有很高的难度。基于改进的DeepLabv3+算法,本文提出一种DeepLabv3-MAC模型,分割自然环境下采集的舌象。首先,将DeepLabv3+模型的主干网络替换为MobileNetv2网络来降... 在自然环境下采集的舌象图像,受光照、背景等因素的影响,其精确分割具有很高的难度。基于改进的DeepLabv3+算法,本文提出一种DeepLabv3-MAC模型,分割自然环境下采集的舌象。首先,将DeepLabv3+模型的主干网络替换为MobileNetv2网络来降低模型复杂度;其次,采用非对称卷积模块增强卷积神经网络的卷积核骨架,提高卷积信息的利用率;最后,引入CBAM注意力机制,不仅能关注空间和通道上参数的重要程度,同时也能提升模型分割精度。实验结果表明,相较于经典的舌象分割算法,本文提出的DeepLabv3-MAC模型具有较好的分割性能,同时,模型的参数量大大减少,可以更快地对自然环境下的舌象进行分割,有利于后期在移动端部署。 展开更多
关键词 舌象分割 DeepLabv3+ DeepLabv3-MAC 非对称卷积模块 CBAM注意力机制
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不对称工况下并网换流器小信号精准建模及其稳定性量化分析
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作者 叶柏贤 王学梅 +3 位作者 冯俊杰 汪娟娟 王泽昊 李芷晴 《南方电网技术》 北大核心 2025年第5期1-15,共15页
阻抗分析法是目前研究新能源并网系统小信号稳定性的常用方法。阻抗建模中,通常假设网侧交流电压三相对称,从而用二阶矩阵即可描述换流器的端口阻抗特性,然而在不对称工况下换流器呈现更复杂的频率耦合特性,模型不再适用。基于此,首先... 阻抗分析法是目前研究新能源并网系统小信号稳定性的常用方法。阻抗建模中,通常假设网侧交流电压三相对称,从而用二阶矩阵即可描述换流器的端口阻抗特性,然而在不对称工况下换流器呈现更复杂的频率耦合特性,模型不再适用。基于此,首先考虑了脉冲宽度调制(pulse width modulation,PWM)的边带效应以及采样环节的频率混叠效应、锁相环动态、直流电压控制、正负序电流内环控制等影响因素,建立了适用于三相不对称工况的并网换流器小信号模型;接着给出了一种不对称工况下多输入多输出(multi-input-multi-output,MIMO)系统降阶为单输入单输出(single-input-single-output,SISO)系统的方法,并通过PSCAD/EMTDC验证了理论分析的正确性;进一步地,定义并网换流器系统的不对称度并分析了控制参数对系统不对称度的影响;在此基础上根据最大峰值奈奎斯特判据分析了不对称工况下控制参数对并网系统稳定性的影响。 展开更多
关键词 并网换流器 脉冲宽度调制(PWM) 不对称工况 单输入单输出等效 最大峰值准则
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改进Unet网络在车道线检测中的应用研究 被引量:1
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作者 孙扬 李韵鹏 +1 位作者 宋建坤 韩磊 《机械设计与制造》 北大核心 2025年第2期325-328,共4页
为了检测复杂道路场景下的车道线,提出了一种改进Unet网络的车道线检测方法。首先引入非对称卷积模块代替原Unet的卷积层,降低网络模型的计算量,压缩网络模型的规模;然后通过金字塔池化结构优化网络对深层语义信息的提取,增强模型对深... 为了检测复杂道路场景下的车道线,提出了一种改进Unet网络的车道线检测方法。首先引入非对称卷积模块代替原Unet的卷积层,降低网络模型的计算量,压缩网络模型的规模;然后通过金字塔池化结构优化网络对深层语义信息的提取,增强模型对深层语义信息的把握;其次在浅层与深层语义信息的融合问题上通过AG模块对深、浅层信息进行筛选,将有利于车道线检测的信息进行特征相加,进一步突显车道线特征。在Tusimple数据集上对该算法进行了训练和评估,实验结果表明,在准确率、误检率和漏检率上比原Unet分别提高了1.35、3.64、2.74%,同时经过实车验证表明该算法能实现在复杂道路情况下的车道线检测任务。 展开更多
关键词 车道线检测 Unet网络 非对称卷积 金字塔池化 AG模块 语义分割
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图腾柱双有源桥AC-DC变换器的非对称扩展移相优化调制策略
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作者 余城洋 李佳 +2 位作者 晏益朋 牟迪 罗全明 《电工技术学报》 北大核心 2025年第8期2560-2572,共13页
单级式图腾柱双有源桥AC-DC变换器具有元件数量少、功率密度高和成本低等优点,在车载充电机等领域具有广阔的应用前景。然而,现有的单移相和扩展移相调制策略由于存在调制自由度不足的问题,而无法对变换器进行多目标的优化,使图腾柱双... 单级式图腾柱双有源桥AC-DC变换器具有元件数量少、功率密度高和成本低等优点,在车载充电机等领域具有广阔的应用前景。然而,现有的单移相和扩展移相调制策略由于存在调制自由度不足的问题,而无法对变换器进行多目标的优化,使图腾柱双有源桥AC-DC变换器在并网电流质量和效率等稳态性能方面仍有提升空间,限制了该变换器在车载充电机中的进一步应用。首次,该文在扩展移相调制策略的基础上引入非对称调制,从而提出具有三个自由度的非对称扩展移相调制策略。其次,对变换器在非对称扩展移相调制下所有可能的工作模式进行分析,并借助时域分析法建立各工作模式的时域稳态分析模型。然后,考虑控制传输功率以实现功率因数校正的同时,进行电感电流初值和峰峰值的多目标优化调制策略求解。最后,相比传统的单移相和扩展移相调制策略,所提出的非对称扩展移相优化调制策略大幅度提升了变换器的稳态性能:并网电流的质量显著提升,峰值效率提升超过5%和1.5%。所提理论分析和优化结果都在仿真和实验中得到了验证。 展开更多
关键词 图腾柱双有源桥 AC-DC变换器 非对称扩展移相调制 功率因数校正 优化调制策略
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基于压缩图像与YOLOv5模型的架空输电线路缺陷检测技术 被引量:6
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作者 刘敏 姜亮 +2 位作者 田杨阳 张璐 陈岑 《沈阳工业大学学报》 北大核心 2025年第2期152-159,共8页
【目的】输电线路作为电能传输和使用过程中的重要环节,其安全稳定对电力系统的正常运行起着至关重要的作用,因此输电线路日常巡检具有重要作用。重大事故通常由微小缺陷隐患发展而来,日常巡检通常采用人工、无人机、可视化通道等手段,... 【目的】输电线路作为电能传输和使用过程中的重要环节,其安全稳定对电力系统的正常运行起着至关重要的作用,因此输电线路日常巡检具有重要作用。重大事故通常由微小缺陷隐患发展而来,日常巡检通常采用人工、无人机、可视化通道等手段,无论何种方式都需要处理大量可视化、红外或者紫外照片。但由于输电线路的特殊性,架设条件涉及多种环境,其巡检图像背景通常较为复杂,采用人工复核审查的方式精度较高,但对经验依赖较大且效率极低。如何快速、准确地识别架空线路巡检图片是架空输电线路缺陷识别的关键。传统输电线路巡检图片识别方法在复杂背景的干扰下,容易出现缺陷识别精确度不高的问题。【方法】为提高架空输电线路巡检图像复杂背景下的检测准确率,提出了一种兼顾识别效率和准确性的缺陷检测方法。基于压缩图像技术并结合YOLOv5模型,设计了一种基于稀疏卷积的非对称特征聚合压缩算法,将原始图像通过编码减少图像存储所需空间以便于存储和传输,经过信息通道传输到解密器后,再将压缩图像进行解码复原以提升局部集合特征的学习效率。同时,通过融入通道空间注意力模块从特征图中得到注意力通道权重矩阵和空间权重矩阵,并通过权重矩阵判断特征图区域的重要程度,完成对YOLOv5模型处理效率的提升。【结果】将压缩恢复后的图像输入改进YOLOv5模型中,利用通道注意力模块(CAM)和空间注意力模块(SAM)分别对图像进行通道与空间上的注意力数据处理,通过全局平均池化和最大池化处理增强目标区域的特征,并引入空间注意力模块增强通道注意力对特征位置信息的关注,以检测出存在缺陷的设备,并通过实验验证了方法的有效性。【结论】以某架空线路的巡检图像数据集为基础,对检测方法开展训练与测试,结果表明,巡检图像经所提技术压缩后,尺寸明显减小,恢复后的图像尺寸较原图约降低了3 MB且未出现失真;改进YOLOv5模型具有较高的检测精确度,其检测准确率和时间分别为0.91和0.87 s,算法在降低图像尺寸提升检测速度的同时保证了检测准确率。 展开更多
关键词 架空输电线路 缺陷检测 图像压缩 改进YOLOv5模型 非对称特征聚合编解码网络 通道空间注意力模块 逐通道稀疏残差卷积 检测准确率
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All-optical permittivity-asymmetric quasi-bound states in the continuum
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作者 Rodrigo Berte Thomas Possmayer +2 位作者 Andreas Tittl Leonardo de S.Menezes Stefan A.Maier 《Light: Science & Applications》 2025年第7期1923-1933,共11页
Resonances are usually associated with finite systems—the vibrations of clamped strings in a guitar or the optical modes in a cavity defined by mirrors.In optics,resonances may be induced in infinite continuous media... Resonances are usually associated with finite systems—the vibrations of clamped strings in a guitar or the optical modes in a cavity defined by mirrors.In optics,resonances may be induced in infinite continuous media via periodic modulations of their optical properties.Here we demonstrate that periodic modulations of the permittivity of a featureless thin film can also act as a symmetry-breaking mechanism,allowing the excitation of photonic quasi-bound states in the continuum(qBICs).By interfering two ultrashort laser pulses in the unbounded film,transient resonances can be tailored through different parameters of the pump beams.We show that the system offers resonances tunable in wavelength and quality-factor,and spectrally selective enhancement of third-harmonic generation.Due to a fast decay of the permittivity asymmetry,we observe ultrafast dynamics,enabling time-selective near-field enhancement with picosecond precision.Optically induced permittivity asymmetries may be exploited in on-demand weak to ultrastrong light-matter interaction regimes and light manipulation at dynamically chosen wavelengths in lithography-free metasurfaces. 展开更多
关键词 featureless thin film photonic resonances interfering two ultrash ultrashort laser pulses optical modes vibrations clamped strings all optical permittivity asymmetric periodic modulations
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Photonic-assisted FSK signal generation based on carrier phase-shifted double sideband modulation
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作者 Muguang Wang Yu Tang +4 位作者 Jian Sun Jing Zhang Qi Ding Beilei Wu Fengping Yan 《Chinese Optics Letters》 SCIE EI CAS CSCD 2021年第10期109-114,共6页
An approach to generate high-speed and wideband frequency shift keying(FSK)signals based on carrier phase-shifted double sideband(CPS-DSB)modulation is proposed and experimentally validated.The core part of the scheme... An approach to generate high-speed and wideband frequency shift keying(FSK)signals based on carrier phase-shifted double sideband(CPS-DSB)modulation is proposed and experimentally validated.The core part of the scheme is a pair of cascaded polarization-sensitive LiNbO_(3) Mach–Zehnder modulators and phase modulators,whose polarization directions of the principal axes are mutually orthogonal to each other.A proof-of-concept experiment is carried out,where a 0.5 Gb/s FSK signal with the carrier frequencies of 4 and 8 GHz and a 1 Gb/s FSK signal with the carrier frequencies of 8 and 16 GHz are generated successfully. 展开更多
关键词 microwave photonics frequency shift keying polarization-sensitive modulator microwave signals generation carrier phase-shifted double sideband modulation
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