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基于匹配滤波域的PSK雷达信号有源干扰识别算法

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电声技术 2024年第6期48卷 121-128页

作者：常宇阳余建宇西安电子工程研究所

针对复杂电磁环境下相位编码（Phase Shift Key,PSK）信号干扰识别问题，研究瞄准式干扰（Spot Jamming,SJ）、阻塞式干扰（Blocking Jamming,BJ）、线性扫频式干扰（Linear Sweep Jamming,LSJ）、灵巧噪声卷积干扰（Noise Convolution ... 详细信息

针对复杂电磁环境下相位编码（Phase Shift Key,PSK）信号干扰识别问题，研究瞄准式干扰（Spot Jamming,SJ）、阻塞式干扰（Blocking Jamming,BJ）、线性扫频式干扰（Linear Sweep Jamming,LSJ）、灵巧噪声卷积干扰（Noise Convolution Jamming,NCJ）、灵巧噪声乘积干扰（Noise Product Jamming,NPJ）、间歇采样直接转发干扰（InterruptedSampling and Direct Repeater Jamming,ISDJ）、间歇采样重复转发干扰（Interrupted-Sampling and Periodic Repeater Jamming,ISPJ）及间歇采样循环转发式干扰（Interrupted-Sampling and Cyclic Repeater Jamming,ISCJ）的匹配滤波序列，人工提取16维特征组成特征向量放入支持向量机（Support Vector Machine,SVM）进行分类识别。仿真实验表明：干噪比（Jamming Noise Ratio,JNR）为-20～30 dB至16～30 dB时，识别率随JNR的增加而提高；JNR为-2～30 dB时，识别率为94.89%；模拟JNR为-2～30 dB的真实环境时，保留8维特征参数，算法识别率可达93.62%，仅降低1.27%。

关键词：相位编码(PSK) 特征提取匹配滤波支持向量机(SVM)

不同纬度地区航磁三分量矢量解释技术应用研究

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Applied Geophysics 2024年第2期21卷 289-302,420页

作者：郭华王明韩松常畅姚雨暘中国自然资源航空物探遥感中心北京100083 吉林大学长春130000 中国地质科学院地质研究所北京100037 中国地质大学(北京) 100084

我国的航磁三分量勘查系统于2017年研制成功,但是利用大面积性航磁三分量数据开展地质解释研究尚处于起步阶段,通过研究认为垂向分量、东向分量和北向分量数据需要进行化极,虽然相关文献和教材开展了航磁三分量中三个分量的化极理论公... 详细信息

我国的航磁三分量勘查系统于2017年研制成功,但是利用大面积性航磁三分量数据开展地质解释研究尚处于起步阶段,通过研究认为垂向分量、东向分量和北向分量数据需要进行化极,虽然相关文献和教材开展了航磁三分量中三个分量的化极理论公式的推导但并不是最终结果,本文经过深入的理论公式推导首次获得了三个分量的化极理论公式,同时将化极后的三个分量数据得到的磁异常总强度矢量数据的相关意义进行了深入分析,得出磁异常总强度矢量图可以较好地指向磁性地质体的赋存位置,在此基础上设计了单一异常体的简单模型和4个异常体的复杂模型开展理论分析,对不同纬度的三个分量数据化极效果进行了分析,得出虽然在低纬度地区三个分量的化极效果并不理想,但是所绘制的磁异常总强度矢量箭头图却可以不受低纬度化极效果不好的影响,在纬度1°-90°的三个分量数据经过化极后绘制的磁异常总强度矢量箭头总能指向磁性地质体,而且汇聚的矢量箭头的位置还可以反映地质体的埋藏深度,然后将该思路应用于中国北部某地区的航磁三分量数据,所绘制的磁异常总强度矢量箭头图出现了指上和指下的现象,通过研究认为箭头图指上的现象是由于该区域的磁性地质体存在有剩磁现象,通过对比地质资料并得到了验证。

关键词：航磁三分量北向分量东向分量垂向分量磁异常总强度矢量

Inverse-time Backup Protection Based on Unified Characteristic Equation for Distribution Networks with High Proportion of Distributed Generations

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 202-212页

作者： Nana chang Guobing Song Zhongxue chang Yuping Zheng Xingang Yang the School of Electrical Engineering Xi’an Jiaotong UniversityXi’anChina State Key Laboratory of Smart Grid Protection and Control NARI Group CorporationNanjingChina Electric Power Research Institute of State Grid Shanghai Electric Power Company ShanghaiChina

The setting work of backup protection using steady-state current is tedious,and mismatches occasionally occur due to the increased proportion of distributed generations(DGs)connected to the power grid.Thus,there is a practical need to study a backup protection technology that does not require step-by-step setting and can be adaptively coordinated.This paper proposes an action sequence adaptive to fault positions that uses only positive sequence fault component(PSFC)voltage.Considering the influence of DGs,the unified time dial setting can be obtained by selecting specific points.The protection performance is improved by using the adjacent upstream and downstream protections to meet the coordination time interval in the case of metallic faults at the near-and far-ends of the line.Finally,the expression and implementation scheme for inverse-time backup protection(ITBP)based on the unified characteristic equation is given.Simulation results show that this scheme can adapt to DG penetration scenarios and can realize the adaptive coordination of multi-level relays.

关键词： Inverse-time backup protection(ITBP) distributed generation(DG) positive sequence fault component(PSFC)voltage unified characteristic equation adaptive coordination

Cell replacement with stem cell-derived retinal ganglion cells from different protocols

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Neural Regeneration Research 2024年第4期19卷 807-810页

作者： Ziming Luo Kun-Che chang Spencer Center for Vision Research Byers Eye InstituteStanford University School of Medicine Department of Ophthalmology Louis J.Fox Center for Vision RestorationUniversity of Pittsburgh School of Medicine Department of Neurobiology Center of NeuroscienceUniversity of Pittsburgh School of Medicine

Glaucoma,characterized by a degenerative loss of retinal ganglion cells,is the second leading cause of blindness worldwide.There is currently no cure for vision loss in glaucoma because retinal ganglion cells do not regenerate and are not replaced after injury.Human stem cell-derived retinal ganglion cell transplant is a potential therapeutic strategy for retinal ganglion cell degenerative diseases.In this review,we first discuss a 2D protocol for retinal ganglion cell differentiation from human stem cell culture,including a rapid protocol that can generate retinal ganglion cells in less than two weeks and focus on their transplantation outcomes.Next,we discuss using 3D retinal organoids for retinal ganglion cell transplantation,comparing cell suspensions and clusters.This review provides insight into current knowledge on human stem cell-derived retinal ganglion cell differentiation and transplantation,with an impact on the field of regenerative medicine and especially retinal ganglion cell degenerative diseases such as glaucoma and other optic neuropathies.

关键词： cell clumps cell suspension cell transplantation differentiation direct-induced protocol glaucoma optic neuropathy regenerative medicine retinal ganglion cell retinal organoids stem cells

Event-triggered H_(∞) consensus control for input-constrained multi-agent systems via reinforcement learning

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Control Theory and Technology 2024年第1期22卷 25-38页

作者： Jinxuan Zhang chang-E Ren College of Information Engineering Capital Normal UniversityBeijing100089China

This article presents an event-triggered H_(∞) consensus control scheme using reinforcement learning (RL) for nonlinear second-order multi-agent systems (MASs) with control constraints. First, considering control constraints, the constrained H_(∞) consensus problem is transformed into a multi-player zero-sum game with non-quadratic performance functions. Then, an event-triggered control method is presented to conserve communication resources and a new triggering condition is developed for each agent to make the triggering threshold independent of the disturbance attenuation level. To derive the optimal controller that can minimize the cost function in the case of worst disturbance, a constrained Hamilton–Jacobi–Bellman (HJB) equation is defined. Since it is difficult to solve analytically due to its strongly non-linearity, reinforcement learning (RL) is implemented to obtain the optimal controller. In specific, the optimal performance function and the worst-case disturbance are approximated by a time-triggered critic network;meanwhile, the optimal controller is approximated by event-triggered actor network. After that, Lyapunov analysis is utilized to prove the uniformly ultimately bounded (UUB) stability of the system and that the network weight errors are UUB. Finally, a simulation example is utilized to demonstrate the effectiveness of the control strategy provided.

关键词： H_(∞)optimal control Input constrains Multi-agent systems(MASs) Reinforcement learning(RL)

Effect of heat treatment on microstructure and mechanical properties of selective laser-melted PH13-8Mo stainless steel

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Journal of Iron and Steel Research(International) 2024年第4期31卷 945-955页

作者： Yuan Zhang Xiang Liu chang-jun Wang chang Liu School of Material Science and Engineering Kunming University of Science and TechnologyKunming 650093YunnanChina Central Iron&Steel Research Institute Co. Ltd.Beijing 100081China

PH13-8Mo stainless steel powder with high sphericity and well fluidity was prepared by the plasma rotating electrode process.The formed parts with ultra-high purity were manufactured by selective laser melting.The tensile and impact mechanical properties of the printed parts under three heat treatment regimes were compared to those without heat treatment.The microstructure,grain orientation and phase composition were characterized by electron-backscatter diffraction,X-ray diffraction and transmission electron microscopy.The characterization results reveal that the addition of heat treatment makes the grains enlarge,and after different heat treatments,the average grain size from 1.51μm in the printed state increases to 2.78,3.09 and 2.06μm,respectively.The formed parts are mainly composed of martensite and retained austenite.Moreover,the NiAl and M23C precipitates form,which are the major strengthening phases of PH13-8Mo stainless steel.The optimal heat treatment process is 925℃×1 h water cooling(WC)+0℃×2 h air cooling(AC)+540℃×4 h AC.Using this heat treatment process,PH13-8Mo formed parts have the optimal comprehensive mechanical properties:the tensile strength,yield strength and impact energy KU2 are 1492 MPa,1432 MPa and 63 J,respectively.The strengthening and toughening via heat treatment are mainly attributed to dislocation strengthening,the formation of NiAl and M23Co precipitates and the change of volume fraction of the retained austenite.

关键词： High-strength stainless steel-Selective laser melting-Heat treatment Microstructure Mechanical property

A toroidal SAW gyroscope with focused IDTs for sensitivity enhancement

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Microsystems & Nanoengineering 2024年第2期10卷 47-56页

作者： Lu Tian Haitao Zhao Qiang Shen Honglong chang Ministry of Education Key Laboratory of Micro and Nano Systems for Aerospace School of Mechanical EngineeringNorthwestern Polytechnical UniversityXi’an710072China

A surface acoustic wave(SAW)gyroscope measures the rate of rotational angular velocity by exploiting a phenomenon known as the SAW gyroscope effect.Such a gyroscope is a great candidate for application in harsh environments because of the simplification of the suspension vibration mechanism necessary for traditional microelectromechanical system(MEMS)gyroscopes.Here,for the first time,we propose a novel toroidal standing-wave-mode SAW gyroscope using focused interdigitated transducers(FIDTs).Unlike traditional SAW gyroscopes that use linear IDTs to generate surface acoustic waves,which cause beam deflection and result in energy dissipation,this study uses FIDTs to concentrate the SAW energy based on structural features,resulting in better focusing performance and increased SAW amplitude.The experimental results reveal that the sensitivity of the structure is 1.51µV/(°/s),and the bias instability is 0.77°/s,which are improved by an order of magnitude compared to those of a traditional SAW gyroscope.Thus,the FIDT component can enhance the performance of the SAW gyroscope,demonstrating its superiority for angular velocity measurements.This work provides new insights into improving the sensitivity and performance of SAW gyroscopes.

关键词： angular deflection gyroscope

Generic Modeling and Control Framework for Power Systems Dominated by Power Converters Connected Through a Passive Transmission and Distribution Grid

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 292-301页

作者： Qing-chang Zhong Marcio Stefanello Department of Electrical and Computer Engineering Illinois Institute of TechnologyChicagoIL 60616USA Syndem LLC USA.M.Stefanello is with the Fundacao Universidade Federal do Pampa at AlegreteRS97546-550Brazil

In this paper,a compact mathematical model having an elegant structure,together with a generic control framework,are proposed for generic power systems dominated by power converters that are interconnected through a passive transmission and distribution(T&D)grid,by adopting the port-Hamiltonian(pH)systems theory and the fundamental circuit theory.The models of generic T&D lines are developed and then the model of a generic T&D grid is established.With the proposed control framework,the controlled converters are proven to be passive and Input-to-State Stable(ISS).The compact mathematical model is scalable and can be applied to power systems with multiple power electronic converters with generic passive controllers,passive local loads,and different types of passive T&D lines connected in a meshed configuration without self-loops,so it is very generic.Moreover,the resulting power system is proven to be ISS as well.The analysis is carried out without assumptions on constant frequency/voltage,constant loads,and/or lossless networks,except the need of passivity for all parts involved,and without using the Clarke/Park transformations or the graph theory.To simplify the presentation,three-phase balanced systems are adopted but the results can be easily adapted for single-phase or unbalanced three-phase systems.

关键词： Input-to-State Stable(ISS) passivity,portHamiltonian(pH)systems Power electronic converters dominated power systems Synchronized and Democratized(SYNDEM)grid architecture

Turning point of organoid transplantation:first-in-human trial of iPSC-derived retinal organoid grafting in patients with retinitis pigmentosa

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Science China(Life Sciences) 2024年第5期67卷 1082-1084页

作者： chang-Jun Zhang Zi-Bing Jin Beijing Institute of Ophthalmology Beijing Tongren HospitalCapital Medical UniversityBeijing 100730China

The discovery of induced pluripotent stem cells(iPSCs)has revolutionized the field of disease research,providing a promising platform for studying various conditions.Over the last decade,significant progress has been made in combining iPSCs with other cutting-edge technologies to investigate disease mechanisms and develop potential treatments.

关键词： conditions patients retinitis