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基于深度特征协作的舰船目标分类方法
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作者 李英 李至立 +3 位作者 胡载萍 江练金 郑红 刘兴惠 《舰船科学技术》 北大核心 2024年第23期174-178,共5页
针对现有的舰船目标分类方法对舰船细粒度分类性能不佳、舰船图像特征学习效果差的问题,提出一种深度特征协作的舰船目标分类算法。首先,搭建双分支ResNet-18网络结构;然后引入对比学习的思想,实现双分支特征信息互补,丰富舰船图像特征... 针对现有的舰船目标分类方法对舰船细粒度分类性能不佳、舰船图像特征学习效果差的问题,提出一种深度特征协作的舰船目标分类算法。首先,搭建双分支ResNet-18网络结构;然后引入对比学习的思想,实现双分支特征信息互补,丰富舰船图像特征学习;最后,通过特征协作模块,对学习到的双分支对比特征进行深度信息整合,以最小化分类损失,进而提高分类结果。在舰船图像数据集FGSC-23上的大量实验结果表明,对23类细粒度舰船图像分类平均准确率达到83.56%。 展开更多
关键词 深度特征协作 对比学习 舰船目标分类
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PIC simulation of plasma properties in the discharge channel of a pulsed plasma thruster with flared electrodes 被引量:3
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作者 Qi LIU Lei YANG +2 位作者 Yuping HUANG Xu ZHAO zaiping zheng 《Plasma Science and Technology》 SCIE EI CAS CSCD 2019年第7期45-53,共9页
Plasma in the discharge channel of a pulsed plasma thruster(PPT) with flared electrodes is simulated by a self-developed two-dimensional code. The fully particle-in-cell method with Monte Carlo collision is employed t... Plasma in the discharge channel of a pulsed plasma thruster(PPT) with flared electrodes is simulated by a self-developed two-dimensional code. The fully particle-in-cell method with Monte Carlo collision is employed to model the particle movement and collisions and investigate the plasma properties and acceleration process. Temporal and spatial variations of the electron density distribution and the ion velocity between electrodes are calculated and analyzed in detail.The computational results of the electron number density, which is in the order of 1023 m-3,show good agreements with experimental results of a PPT named ADD SIMP-LEX. The ion velocity distributions along the center line of the channel lead to a comprehensive understanding of ions accelerated by electromagnetic field. The electron distributions of PPT with discharge voltages varying from 1300 to 2000 V are compared. The diffusion of electrons presents strong dependency on discharge voltage and implies higher degree of ionization for higher voltage. 展开更多
关键词 PULSED plasma THRUSTER DISCHARGE channel PIC simulation electron density distribution ion ACCELERATION
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Investigation of the self-induced magnetic field characteristics in a pulsed plasma thruster with flared electrodes 被引量:1
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作者 Qi LIU Lei YANG +2 位作者 Yuping HUANG Xu ZHAO zaiping zheng 《Plasma Science and Technology》 SCIE EI CAS CSCD 2020年第3期46-53,共8页
The self-induced magnetic field in a pulsed plasma thruster(PPT)with flared electrodes is investigated for a better understanding of the working process and the structural design of the thruster.A two-dimensional mode... The self-induced magnetic field in a pulsed plasma thruster(PPT)with flared electrodes is investigated for a better understanding of the working process and the structural design of the thruster.A two-dimensional model of the magnetic field is built and is validated by comparing the simulated results with the experimental results in literature.The magnetic flux density in the discharge channel during the working process is presented and analyzed regarding the electrode structures.The calculated magnetic field flux density decreases from 0.8 T at the upstream to 0.1 T and below at the downstream in the discharge channel(68 J).The peak of the magnetic flux density over time lags behind the current peak,which provides evidence for the existence of a moving plasma sheet in the discharge process.The magnetic field induced by the current in the extra bending part of the anode enhances the Lorentz force,which acts on the charged particles near the propellant.Finally,the geometric study indicates that the electromagnetic impulse bit does not monotonically increase with the flared angle of the electrodes.Instead,it reaches a maximum at a certain flared angle,which could provide significant suggestions for structural optimization. 展开更多
关键词 PULSED plasma THRUSTER numerical INVESTIGATION magnetic FLUX DENSITY flared ELECTRODES
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