By applying phase-only technique in array antenna pattern synthesis, antenna arrays can form desired patterns with the use of phase shifters only. A novel phase-only pattern synthesis algorithm is proposed for the pas...By applying phase-only technique in array antenna pattern synthesis, antenna arrays can form desired patterns with the use of phase shifters only. A novel phase-only pattern synthesis algorithm is proposed for the passive phased array seeker. This algorithm synthesizes the main beam of the antenna pattern through least-squares approximation, thus minimizing the errors between the actual and the desired main beams. The synthesis problem can be solved by applying gradient-descent optimization. The item for suppressing side lobes is added to the above synthesis problem. To obtain a side lobe level as low as possible, the algorithm assigns different weights to different directions in the side lobe region. The algorithm is run repeatedly and the weights are adjusted adaptively according to the normalized power in the side lobe directions. Detailed examples are presented to demonstrate the accuracy and effectiveness of the proposed approach.展开更多
Metasurfaces have revolutionized planar optics due to their prominent ability in light field manipulation.Recently,the incorporation of machine learning has further improved computational efficiency and reduced the re...Metasurfaces have revolutionized planar optics due to their prominent ability in light field manipulation.Recently,the incorporation of machine learning has further improved computational efficiency and reduced the reliance on professionals in designing various metasurfaces.However,the prevalent methods still suffer from configuration complexity and expensive training costs due to more than one model or a combination of rule-driven algorithms.This study proposes a deep learningbased paradigm using only one deep learning model for the end-to-end design of versatile metasurfaces.The adopted deepenhanced RseNet acts both as the surrogate of the electromagnetic simulator in forward spectrum prediction and as the path for backward gradient descent optimization of the meta-atom structures in the paralleled calculation.Without loss of generality,a polarization-multiplexing holographic and a polarization-independent vortex metasurface were designed by this paradigm and successfully demonstrated in the terahertz range.The extremely simplified framework presented here will not only propel the design and application of metasurfaces in terahertz communication and imaging fields,but its universality will also accelerate the research and development of subwavelength planar optics across various wavelengths through artificial intelligence[AI]-enhanced design for optical devices.展开更多
为了保障网络环境的安全性,提出了基于集成式图卷积神经网络算法的网络入侵检测技术。研究方法采用随机梯度下降算法和均方根传播(Root Mean Square Propagation,RMSProp)优化器提升了检测模型的训练效率,强化了检测模型的分类效果。研...为了保障网络环境的安全性,提出了基于集成式图卷积神经网络算法的网络入侵检测技术。研究方法采用随机梯度下降算法和均方根传播(Root Mean Square Propagation,RMSProp)优化器提升了检测模型的训练效率,强化了检测模型的分类效果。研究结果显示,研究模型的入侵检测准确率为96.41%~97.18%。可见经过研究模型优化后,入侵检测技术在模型训练效率和模型训练精度上都有明显提升。研究模型可以根据访问来源进行数据分类,提升了入侵检测模型对访问行为的分类效果。同时,分类效果的提升优化了计算机对攻击行为的识别效率,使计算机的防御效果增强,有效保障了用户的网络安全环境。因此,研究为网络入侵行为的检测提供了一个识别效果较好的技术方法。展开更多
交替方向乘子法(Alternating Direction Method of Multiplier,ADMM)因具有线性规划(Linear Programming,LP)译码条件约束的几何结构,同时利用了消息传递机制,被认为是一种第5代移动通信技术(5th Generation Mobile Communication Techn...交替方向乘子法(Alternating Direction Method of Multiplier,ADMM)因具有线性规划(Linear Programming,LP)译码条件约束的几何结构,同时利用了消息传递机制,被认为是一种第5代移动通信技术(5th Generation Mobile Communication Technology,5G)低密度校验(Low Density Parity Check,LDPC)码新型优化译码算法。通过在LP译码模型的目标函数中引入惩罚项,基于ADMM的变量节点惩罚译码有效地减轻了非积分解,从而提高了误帧率(Frame Error Rate,FER)性能。尽管ADMM在许多实际应用中表现出色,其收敛速度较慢以及对初始条件和参数设置敏感的问题仍然限制了其在高维、实时性要求高的场景中的进一步应用。特别是在LDPC线性规划译码过程中,ADMM的交替更新机制容易导致优化路径振荡,且在处理非精确约束时表现不佳。针对ADMM算法收敛速度慢的问题,我们提出了一种新的优化算法,该算法将Nesterov动量加速方法与ADMM相结合,以解决ADMM对LDPC译码器错误修正能力和收敛效率的影响。算法通过动量项减少迭代次数将一个Nesterov加速格式从无约束复合优化问题推广到ADMM惩罚函数模型,利用ADMM算法将原问题的约束条件有效转化为目标函数的一部分,从而构造出无约束优化子问题;在此基础上,进一步采用Nesterov加速技术对梯度下降迭代过程进行改进,以提高收敛速度和求解精度。仿真实验使用了三种不同码率的5G LDPC短码。结果表明,相对于现有ADMM惩罚译码算法,所提出的基于动量加速的ADMM译码算法不仅有大约0.2 dB的信噪比增益,而且平均迭代次数也降低了20%左右,加快了收敛速度。展开更多
基金supported by the National Natural Science Foundation of China(1127301761471196)
文摘By applying phase-only technique in array antenna pattern synthesis, antenna arrays can form desired patterns with the use of phase shifters only. A novel phase-only pattern synthesis algorithm is proposed for the passive phased array seeker. This algorithm synthesizes the main beam of the antenna pattern through least-squares approximation, thus minimizing the errors between the actual and the desired main beams. The synthesis problem can be solved by applying gradient-descent optimization. The item for suppressing side lobes is added to the above synthesis problem. To obtain a side lobe level as low as possible, the algorithm assigns different weights to different directions in the side lobe region. The algorithm is run repeatedly and the weights are adjusted adaptively according to the normalized power in the side lobe directions. Detailed examples are presented to demonstrate the accuracy and effectiveness of the proposed approach.
基金supported by the National Natural Science Foundation of China(Nos.62027820,61975143,62375203,62175180,and 61735012)。
文摘Metasurfaces have revolutionized planar optics due to their prominent ability in light field manipulation.Recently,the incorporation of machine learning has further improved computational efficiency and reduced the reliance on professionals in designing various metasurfaces.However,the prevalent methods still suffer from configuration complexity and expensive training costs due to more than one model or a combination of rule-driven algorithms.This study proposes a deep learningbased paradigm using only one deep learning model for the end-to-end design of versatile metasurfaces.The adopted deepenhanced RseNet acts both as the surrogate of the electromagnetic simulator in forward spectrum prediction and as the path for backward gradient descent optimization of the meta-atom structures in the paralleled calculation.Without loss of generality,a polarization-multiplexing holographic and a polarization-independent vortex metasurface were designed by this paradigm and successfully demonstrated in the terahertz range.The extremely simplified framework presented here will not only propel the design and application of metasurfaces in terahertz communication and imaging fields,but its universality will also accelerate the research and development of subwavelength planar optics across various wavelengths through artificial intelligence[AI]-enhanced design for optical devices.
文摘为了保障网络环境的安全性,提出了基于集成式图卷积神经网络算法的网络入侵检测技术。研究方法采用随机梯度下降算法和均方根传播(Root Mean Square Propagation,RMSProp)优化器提升了检测模型的训练效率,强化了检测模型的分类效果。研究结果显示,研究模型的入侵检测准确率为96.41%~97.18%。可见经过研究模型优化后,入侵检测技术在模型训练效率和模型训练精度上都有明显提升。研究模型可以根据访问来源进行数据分类,提升了入侵检测模型对访问行为的分类效果。同时,分类效果的提升优化了计算机对攻击行为的识别效率,使计算机的防御效果增强,有效保障了用户的网络安全环境。因此,研究为网络入侵行为的检测提供了一个识别效果较好的技术方法。
文摘交替方向乘子法(Alternating Direction Method of Multiplier,ADMM)因具有线性规划(Linear Programming,LP)译码条件约束的几何结构,同时利用了消息传递机制,被认为是一种第5代移动通信技术(5th Generation Mobile Communication Technology,5G)低密度校验(Low Density Parity Check,LDPC)码新型优化译码算法。通过在LP译码模型的目标函数中引入惩罚项,基于ADMM的变量节点惩罚译码有效地减轻了非积分解,从而提高了误帧率(Frame Error Rate,FER)性能。尽管ADMM在许多实际应用中表现出色,其收敛速度较慢以及对初始条件和参数设置敏感的问题仍然限制了其在高维、实时性要求高的场景中的进一步应用。特别是在LDPC线性规划译码过程中,ADMM的交替更新机制容易导致优化路径振荡,且在处理非精确约束时表现不佳。针对ADMM算法收敛速度慢的问题,我们提出了一种新的优化算法,该算法将Nesterov动量加速方法与ADMM相结合,以解决ADMM对LDPC译码器错误修正能力和收敛效率的影响。算法通过动量项减少迭代次数将一个Nesterov加速格式从无约束复合优化问题推广到ADMM惩罚函数模型,利用ADMM算法将原问题的约束条件有效转化为目标函数的一部分,从而构造出无约束优化子问题;在此基础上,进一步采用Nesterov加速技术对梯度下降迭代过程进行改进,以提高收敛速度和求解精度。仿真实验使用了三种不同码率的5G LDPC短码。结果表明,相对于现有ADMM惩罚译码算法,所提出的基于动量加速的ADMM译码算法不仅有大约0.2 dB的信噪比增益,而且平均迭代次数也降低了20%左右,加快了收敛速度。
