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Super-resolution diffractive neural network for alloptical direction of arrival estimation beyond diffraction limits

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Light(Science & Applications) 2024年第8期13卷 1602-1614页

作者： Sheng Gao Hang Chen yichen Wang Zhengy.ng Duan haiou Zhang Zhi Sun yuan Shen Xing Lin Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Beijing National Research Center for Information Science and Technology Tsinghua UniversityBeijing 100084China

Wireless sensing of the wave propagation direction from radio sources lays the foundation for communication,radar,navigation,***,the existing signal processing paradigm for the direction of arrival estimation requires the radio frequency electronic circuit to demodulate and sample the multichannel baseband signals followed by a complicated computing process,which places the fundamental limit on its sensing speed and energy ***,we propose the super-resolution diffractive neural networks(S-DNN)to process electromagnetic(EM)waves directly for the DOA estimation at the speed of *** multilayer meta-structures of S-DNN generate super-oscillatory angular responses in local angular regions that can perform the all-optical DOA estimation with angular resolutions beyond the diffraction *** spatial-temporal multiplexing of passive and reconfigurable S-DNNs is utilized to achieve high-resolution DOA estimation over a wide field of *** S-DNN is validated for the DOA estimation of multiple radio sources over 5 GHz frequency bandwidth with estimation latency over two to four orders of magnitude lower than the state-of-the-art commercial devices in *** results achieve the angular resolution over an order of magnitude,experimentally demonstrated with four times,higher than diffraction-limited *** also apply S-DNN’s edge computing capability,assisted by reconfigurable intelligent surfaces,for extremely low-latency integrated sensing and communication with low power *** work is a significant step towards utilizing photonic computing processors to facilitate various wireless sensing and communication tasks with advantages in both computing paradigms and performance over electronic computing.

关键词： beyond optical network

Downstream Competition and Upstream Innovation:Theory and Evidence from China

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China Finance and Economic Review 2024年第1期13卷 67-87页

作者： Jing Dai Guanchun Liu Ziqi ye haiou Mao y.ngwei ye School of Finance Hubei University of Economics Lingnan College Sun Yatsen University School of Business Administration Zhongnan University of Economics and Law College of Economics and Management Huazhong Agricultural University School of Public Economics and Management Shanghai University of Finance and Economics

Competition is the catalyst of corporate innovation,which is the foundation of a country's core *** the view of vertical industrial chain,this paper examines how downstream competition affects upstream firms'innovation *** innovation helps reduce the production cost of each product,increasing demand of intermediate products caused by downstream competition enhances the marginal revenue of upstream firms'innovation,thus leading to an innovation incentive *** identify causality,we utilize China's WTO accession,a quasinatural experiment,to calculate downstream competition combined with import tariff reduction and input-output table,and then run a difference-in-difference *** the data of Annual Survey of Industrial Firms and State Intellectual Property Office,our results find that downstream competition has a significantly positive impact on upstream firms'innovation,and this effect is more pronounced in firms with less industry competition,greater initial innovation capacity and weaker financial ***,the number of firms,the degree of industry competition and the scale of intermediate products in the downstream sector increase,confirming the market size *** sum,our findings document that downstream competition can motivate upstream firms to innovate through vertical industrial chain,providing some useful insights for China to build a fair market competition environment and promote innovation-driven growth regime.

关键词： downstream competition upstream firms'innovation vertical industrial chain market size effect

Toward understanding the microstructure characteristics,phase selection and magnetic properties of laser additive manufactured Nd-Fe-B permanent magnets

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International Journal of Extreme Manufacturing 2024年第1期6卷 277-294页

作者： Bo yao Nan Kang Xiangyu Li Dou Li Mohamed EL Mansori Jing Chen haiou y.ng Hua Tan Xin Lin State Key Laboratory of Solidiffcation Processing Northwestern Polytechnical UniversityXi’anShaanxi 710072People’s Republic of China Arts et Metiers Institute of Technology MSMPHESAM UniversitéF-51006 Chˆalons-en-ChampagneFrance Key Laboratory of Metal High Performance Additive Manufacturing and Innovative Design MIIT ChinaNorthwestern Polytechnical UniversityXi’anShaanxi 710072People’s Republic of China Texas A&M Engineering Experiment Station Institute for Manufacturing SystemsCollege StationTX 77843United States of America

Nd-Fe-B permanent magnets play a crucial role in energy conversion and electronic *** essential magnetic properties of Nd-Fe-B magnets,particularly coercivity and remanent magnetization,are significantly infuenced by the phase characteristics and *** this work,Nd-Fe-B magnets were manufactured using vacuum induction melting(VIM),laser directed energy deposition(LDED)and laser powder bed fusion(LPBF)*** evolution and phase selection of Nd-Fe-B magnets were then clarified in *** results indicated that the solidification velocity(V)and cooling rate(R)are key factors in the phase *** terms of the VIM-casting Nd-Fe-B magnet,a large volume fraction of theα-Fe soft magnetic phase(39.7 vol.%)and Nd2Fe17Bxmetastable phase(34.7 vol.%)areformed due to the low R(2.3×10-1?C s-1),whereas only a minor fraction of the Nd2Fe14B hard magnetic phase(5.15 vol.%)is *** the LDED-processed Nd-Fe-B deposit,although the Nd2Fe14B hard magnetic phase also had a low value(3.4 vol.%)as the values of V(ng and LDED-processed Nd-Fe-B deposits exhibited poor magnetic *** contrast,employ.ng the high values of V(>10-2m s-1)and R(1.45×106?C s-1)in the LPBF process resulted in the substantial formation of the Nd2Fe14B hard magnetic phase(55.8 vol.%)directly from the liquid,while theα-Fe soft magnetic phase and Nd2Fe17Bxmetastable phase precipitation are suppressed in the LPBF-processed Nd-Fe-B ***,crystallographic texture analysis reveals that the LPBF-processedNd-Fe-B magnets exhibit isotropic magnetic ***,the LPBF-processed Nd-Fe-B deposit,exhibiting a coercivity of 656 k A m-1,remanence of 0.79 T and maximum energy product of 71.5 k J m-3,achieved an acceptable magnetic perfor

关键词： laser additive manufacturing(LAM) Nd-Fe-B permanent magnets numerical simulation microstructure magnetic properties

An Innovative Finite Element Geometric Modeling of Single-Layer Multi-Bead WAAMed Part

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Computer Modeling in Engineering & Sciences 2024年第3期138卷 2383-2401页

作者： Xiangman Zhou Jingping Qin Zichuan Fu Min Wang youlu yuan Junjian Fu haiou Zhang Seyed Reza Elmi Hosseini College of Mechanical and Power Engineering China Three Gorges UniversityYichang443002China School of Mechanical Science and Engineering Huazhong University of Science and TechnologyWuhan430074China School of Metallurgy and Materials Engineering Iran University of Science and TechnologyNarmakIran

Finite element (FE) coupled thermal-mechanical analysis is widely used to predict the deformation and residualstress of wire arc additive manufacturing (WAAM) parts. In this study, an innovative single-layermulti-bead profilegeometric modeling method through the isosceles trapezoid function is proposed to build the FE model of theWAAMprocess. Firstly, a straight-line model for overlapping beads based on the parabola function was establishedto calculate the optimal center distance. Then, the isosceles trapezoid-based profile was employed to replace theparabola profiles of the parabola-based overlapping model to establish an innovative isosceles trapezoid-basedmulti-bead overlapping geometric model. The rationality of the isosceles trapezoid-based overlapping model wasconfirmed by comparing the geometric deviation and the heat dissipation performance index of the two overlappingmodels. In addition, the FE-coupled thermal-mechanical analysis, as well as a comparative experiment of thesingle-layer eight-bead deposition process show that the simulation results of the above two models agree with theexperimental results. At the same time, the proposed isosceles trapezoid-based overlappingmodels are all straightlineprofiles, which can be divided into high-quality FE elements. It can improve the modeling efficiency andshorten the simulation calculation time. The innovative modeling method proposed in this study can provide anefficient and high-precision geometricmodelingmethod forWAAMpart FE coupled thermal-mechanical analysis.

关键词： WAAM FE coupled thermal-mechanical analysis the isosceles trapezoid-based model residual stress

EEG光子处理器——基于衍射光子计算单元的癫痫发作检测

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Engineering 2024年第4期35卷 56-66页

作者： Tao yan Maoqi Zhang Hang Chen Sen Wan Kaifeng Shang haiou Zhang Xun Cao Xing Lin Qionghai Dai Department of Automation Tsinghua UniversityBeijing 100084China Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Institute for Brain and Cognitive Sciences Tsinghua UniversityBeijing 100084China School of Electronic Science and Engineering Nanjing UniversityNanjing 210023China Beijing National Research Center for Information Science and Technology Tsinghua UniversityBeijing 100084China

Electroencephalography(EEG)analysis extracts critical information from brain signals,enabling brain disease diagnosis and providing fundamental support for brain–computer ***,performing an artificial intelligence analysis of EEG signals with high energy efficiency poses significant challenges for electronic processors on edge computing devices,especially with large neural network ***,we propose an EEG opto-processor based on diffractive photonic computing units(DPUs)to process extracranial and intracranial EEG signals effectively and to detect epileptic *** signals of the EEG channels within a second-time window are optically encoded as inputs to the constructed diffractive neural networks for classification,which monitors the brain state to identify symptoms of an epileptic *** developed both free-space and integrated DPUs as edge computing systems and demonstrated their applications for real-time epileptic seizure detection using benchmark datasets,that is,the Children’s Hospital Boston(CHB)–Massachusetts Institute of Technology(MIT)extracranial and Epilepsy-iEEG-Multicenter intracranial EEG datasets,with excellent computing performance *** with the channel selection mechanism,both numerical evaluations and experimental results validated the sufficiently high classification accuracies of the proposed opto-processors for supervising clinical *** study opens a new research direction for utilizing photonic computing techniques to process large-scale EEG signals and promote broader applications.

关键词： Epileptic seizure detection EEG analysis Diffractive photonic computing unit Photonic computing

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基于深度学习的锂电池故障分析及应用

储能科学与技术 2024年第6期13卷 2054-2056页

作者：时海欧濮阳职业技术学院河南大学濮阳工学院河南濮阳457000

锂电池储能在清洁能源使用、电动汽车、移动设备以及再生能源存储领域都有极其重要的作用。一旦出现故障很容易引起一系列问题,所以对其进行故障分析,了解其实时健康状态具有重要意义。本文对深度学习机制下的锂电池故障分析技术进行综... 详细信息

锂电池储能在清洁能源使用、电动汽车、移动设备以及再生能源存储领域都有极其重要的作用。一旦出现故障很容易引起一系列问题,所以对其进行故障分析,了解其实时健康状态具有重要意义。本文对深度学习机制下的锂电池故障分析技术进行综述。在深入了解包括多层感知、循环神经网络等深度学习诊断理论的基础上,阐述了最新的锂电池故障诊断模型(LSTM)的评估框架及流程。通过实际应用可以判定基于深度学习的锂电池故障分析模型具有可循环性高、精确度好等优点,值得更深入的研究探讨。

关键词：深度学习锂电池评估模型

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侧向轧制变胞机构的动力学仿真与优化设计

华中科技大学学报（自然科学版） 2024年第6期52卷 56-62页

作者：孙乐乐张海鸥华中科技大学机械科学与工程学院湖北武汉430074

为了解决电弧增材制造存在变形及微观组织形态和力学性能较差的问题,采用轧制使材料的力学性能得到极大改善.为了合理设计轧制机构,针对一种侧向轧制变胞机构进行动力学分析和优化设计,分别分析了杆件尺寸、主动件速度、弹簧刚度在变胞... 详细信息

为了解决电弧增材制造存在变形及微观组织形态和力学性能较差的问题,采用轧制使材料的力学性能得到极大改善.为了合理设计轧制机构,针对一种侧向轧制变胞机构进行动力学分析和优化设计,分别分析了杆件尺寸、主动件速度、弹簧刚度在变胞机构运动过程中对变胞机构的影响.首先,分析了侧向轧制变胞机构的原理,得到了机构的基本结构;然后,选取合适的设计变量初始值与边界值,确定目标函数及约束条件;最后,在机械系统动力学自动分析(ADAMS)软件中建立机构的虚拟样机模型,在一定的侧向轧制力下,以主动件的驱动力最小为优化目标进行仿真求解,得到驱动力的最优解和相应设计变量的最优值.结果表明:最小驱动力较优化前减小了15.48%,主动件速度、杆件尺寸、弹簧刚度对变胞机构的影响程度是依次减弱的.

关键词：变胞机构电弧增材制造优化设计动态仿真机械系统动力学自动分析(ADAMS)

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从杨叔子看大先生之大

高教探索 2024年第3期 5-10页

作者：罗海鸥华中科技大学教育科学研究院武汉430074 广东开放大学

杨叔子(1933-2022)是中国科学院院士、华中科技大学(原华中理工大学)老校长、教授。称杨叔子为大先生比其他称谓都恰切。杨叔子作为大先生,大在哪里?从个体特殊性而言,大在其集科学家、思想家和教育家于一身;从普遍性上来说,大在其具有... 详细信息

杨叔子(1933-2022)是中国科学院院士、华中科技大学(原华中理工大学)老校长、教授。称杨叔子为大先生比其他称谓都恰切。杨叔子作为大先生,大在哪里?从个体特殊性而言,大在其集科学家、思想家和教育家于一身;从普遍性上来说,大在其具有大情怀、大学问和大德行。从杨叔子身上感悟大先生之大,弘扬教育家精神,对于加快教育强国建设、全面推动中华民族伟大复兴具有重要意义。

关键词：杨叔子大先生情怀学问德行

基于光纤的传感物联网吞吐量最大化中继节点选择

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传感技术学报 2024年第2期37卷 339-344页

作者：马青云刘海鸥广州软件学院电子系广东广州510900 广州软件学院计算机系广东广州510900

中继节点是传感物联网通信的中转中心,其选择的合理性对保证物联网通信稳定和信息吞吐量具有重要意义。提出基于光纤的传感物联网吞吐量最大化中继节点选择方法。构建传感物联网模型,在平面中任意布局节点,利用所在点数据整合全部节点,... 详细信息

中继节点是传感物联网通信的中转中心,其选择的合理性对保证物联网通信稳定和信息吞吐量具有重要意义。提出基于光纤的传感物联网吞吐量最大化中继节点选择方法。构建传感物联网模型,在平面中任意布局节点,利用所在点数据整合全部节点,在目标光纤传感器基站中找出主瓣,识别光源节点传输的信号。计算节点能量平均数,在自适应状态中将能量的分母最小化。在候选节点选取可将已知的光信道状态完整传输给其他节点的中继节点,基于统计独立分布获得系统平均接收信噪比,选择光纤传感器天线完成吞吐量最大化中继节点选择。仿真结果表明,所提方法在节点数量为22时的中断概率趋近于0;在光源节点功率30 dBm时,网络吞吐率达到98%。

关键词：光纤传感器物联网技术中继节点选择网络吞吐量光纤信噪比