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ⅢA-ⅡB multicomponent perovskite rare earth ferrites with promising electromagnetic wave absorption properties

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Journal of Rare Earths 2024年第6期42卷 1118-1127,I0005页

作者： Yanyan He Tao Chen Yanyu Pan Minzhong Huang Kaixian Wang Liyan Xue Yazhu Li Fengzhi Tan Fan Yang Tongkuan Xu Heng Chen School of Light Industry and Chemical Engineering Dalian Polytechnic UniversityDalian116034China Xiamen institute of Rare EarthMaterials Haixi InstitutesChinese Academy of SciencesXiamen36021China Fujian institute of Research on the Structure of Matter Chinese Academyof SciencesFuzhou350002China Fujian Science&Technology innovation Laboratory for Optoelectronic information of China Fuzhou350108China Xiamen Key-Laboratoryof Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth MaterialsHaixi InstituteChinese Academy of SciencesXiamen361021China Key Laboratory of Rare Earths Ganjiang Innovation AcademyChinese Academy of SciencesGanzhou3410ooChina

Perovskite-type rare-earth ferrites(REFeO_(3))are promising materials for absorbing electromagnetic(EM)wave ***,insufficient dielectric loss and poor impedance matching are key factors that limit the broader implementation of REFeO_(3).Herein,a series of multicomponent perovskite-type ferrites with strong EM wave absorption capabilities was *** the synergistic effect of chemical constitution regulation and entropy regulation,optimization of the dielectric loss and impedance matching is achieved by strengthening the structural defect mechanism,thus further adjusting the EM wave absorption *** with(LaGdSmNdBa)FeO_(3)(HE-1)and(LaGdPrSmNdBa)FeO_(3)(HE-2),(LaGdBa)FeO_(3)(ME-1)and(LaGdSmBa)FeO_(3)(ME-2)exhibit favorable performance,with optimal minimum reflection loss(RL_(min))of-56.35 dB(at 11.12 GHz)and-63.25 dB(at 7.22 GHz)and effective absorption bandwidth(EAB)of 4.46 and 4.72 GHz,*** multicomponent design provides a new strategy for the development of EM wave absorption materials.

关键词： Rare earths Multicomponent design Rare earth ferrites Entropy regulation Electromagnetic wave absorption

A Novel Clutter Suppression Algorithm for Low-Slow-Small Targets Detecting Based on Sparse Adaptive Filtering

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Journal of Beijing institute of Technology 2024年第1期33卷 54-64页

作者： Zeqi Yang Shuai Ma Ning Liu Kai Chang Xiaode Lyu aerospace information Research institute Chinese Academy of SciencesBeijing 100094China National Key Laboratory of Microwave Imaging Technology Beijing 100190China School of Electronic Electrical and Communication Engineering University of Chinese Academy of SciencesBeijing 100049China Northern institute of Electronic Equipment Beijing 100083China

Passive detection of low-slow-small(LSS)targets is easily interfered by direct signal and multipath clutter,and the traditional clutter suppression method has the contradiction between step size and convergence *** this paper,a frequency domain clutter suppression algorithm based on sparse adaptive filtering is *** pulse compression operation between the error signal and the input reference signal is added to the cost function as a sparsity constraint,and the criterion for filter weight updating is improved to obtain a purer echo *** the same time,the step size and penalty factor are brought into the adaptive iteration process,and the input data is used to drive the adaptive changes of parameters such as step *** proposed algorithm has a small amount of calculation,which improves the robustness to parameters such as step size,reduces the weight error of the filter and has a good clutter suppression performance.

关键词： passive radar interference suppression sparse representation adaptive filtering

DOA estimation of high-dimensional signals based on Krylov subspace and weighted l_(1)-norm

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Journal of Systems Engineering and Electronics 2024年第3期35卷 532-540,F0002页

作者： YANG Zeqi LIU Yiheng ZHANG Hua MA Shuai CHANG Kai LIU Ning LYU Xiaode aerospace information Research institute Chinese Academy of SciencesBeijing 100094China National Key Laboratory of Microwave Imaging Technology Beijing 100190China School of Electronic Electrical and Communication Engineering University of Chinese Academy of SciencesBeijing 100049China Northern institute of Electronic Equipment Beijing 100191China

With the extensive application of large-scale array antennas,the increasing number of array elements leads to the increasing dimension of received signals,making it difficult to meet the real-time requirement of direction of arrival(DOA)estimation due to the computational complexity of *** subspace algorithms require estimation of the covariance matrix,which has high computational complexity and is prone to producing spurious *** order to reduce the computational complexity of DOA estimation algorithms and improve their estimation accuracy under large array elements,this paper proposes a DOA estimation method based on Krylov subspace and weighted l_(1)-*** method uses the multistage Wiener filter(MSWF)iteration to solve the basis of the Krylov subspace as an estimate of the signal subspace,further uses the measurement matrix to reduce the dimensionality of the signal subspace observation,constructs a weighted matrix,and combines the sparse reconstruction to establish a convex optimization function based on the residual sum of squares and weighted l_(1)-norm to solve the target *** results show that the proposed method has high resolution under large array conditions,effectively suppresses spurious peaks,reduces computational complexity,and has good robustness for low signal to noise ratio(SNR)environment.

关键词： direction of arrival(DOA) compressed sensing(CS) Krylov subspace l_(1)-norm dimensionality reduction

Two-layer Lagrange-based relay network topology and trajectory design for solar system explorations

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Science China(information Sciences) 2024年第6期67卷 342-358页

作者： Jun CAO Jian JIAO Hao LIU Rongxing LU Qinyu ZHANG Guangdong Provincial Key Laboratory of aerospace Communication and Networking Technology Harbin Institute of Technology (Shenzhen) Faculty of Computer Science (FCS) University of New Brunswick

Exploration targeting outer planets and even the edge of the solar system is an emerging direction for the deep-space exploration in the next decades. To address this challenge, a novel two-layer Lagrangebased relay network topology is proposed in this study. Specifically, we utilize the Sun-Mars and Sun-Saturn Lagrange points(LPs) L4 and L5 to build a two-layer backbone relay network, which ensures continuous and high-efficiency communication capability for the exploration of the solar system. Furthermore, we utilize the planetary gravity assist and design the transfer trajectory of backbone relays with the help of planetary celestial body motion equations and Kepler's laws. Moreover, we conduct link budget analysis for multihop relay transmission under Gamma-Gamma distribution, shadowed Rician fading, and additive white Gaussian noise channels in several typical exploration scenarios and validate that the LP relays can effectively support future deep-space exploration missions.

关键词： deep-space communication Lagrangian points backbone relay network transfer trajectory relay selection

Simulation design of thin film lithium niobate electro-optic modulator with bimetallic layer electrodes

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Optoelectronics Letters 2024年第6期20卷 339-345页

作者： WU Qiulin FENG Xinkai CHEN Jiaying MA Lei CHEN Huaixi LIANG Wanguo Fujian institute of Research on the Structure of Matter Chinese Academy of SciencesFuzhou 350108China University of Chinese Academy of Sciences Beijing 100059China Fujian Science&Technology innovation Laboratory for Optoelectronic information of China Fuzhou 350108China1

Thin-film lithium niobate electro-optical modulator will become the key device in the future optical communication,which has the advantages of high modulation rate,low half-wave voltage,large bandwidth,and easy integration compared with conventional bulk lithium niobate ***,because the electrode gap of the lithium niobate film modulator is very narrow,when the microwave frequency gets higher,it leads to higher microwave loss,and the electro-optical performance of the modulator will be greatly ***,we propose a thin film lithium niobate electro-optic modulator with a bimetallic layer electrode structure to achieve microwave loss less than 8 dB/cm in the range of 200 GHz,exhibiting a voltage-length product of 1.1 V·cm and a 3 dB electro-optic bandwidth greater than 160 ***-speed data transmission test has been performed,showing good performance.

关键词： Simulation design of thin film lithium niobate electro-optic modulator with bimetallic layer electrodes

Recent progress on mechanisms,principles,and strategies for high-activity and high-stability non-PGM fuel cell catalyst design

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Carbon Energy 2024年第5期6卷 25-52页

作者： Yuping Yuan Yun Zheng Dan Luo Weibin Qiu Jiantao Wang Xin Wang Zhongwei Chen GRINM(Guangdong)institute of New Materials Technology FoshanChina Department of Chemical Engineering Waterloo Institute for NanotechnologyWaterloo Institute for Sustainable EnergyUniversity of WaterlooWaterlooOntarioCanada Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices School of Information and Optoelectronic Science and EngineeringSouth China Normal UniversityGuangdongChina National Power Battery innovation Center GRINM Group Co.Ltd.BeijingChina

The commercialization of a polymer membrane H2-O2 fuel cell and its widespread use call for the development of cost-effective oxygen reduction reaction(ORR)nonplatinum group metal(NPGM)***,to meet the requests for the real-world fuel cell application and replacing platinum catalysts,it still needs to address some challenges for NPGM catalysts regarding the sluggish ORR kinetics in the cathode and their poor durability in acidic *** response to these issues,numerous efforts have been made to study NPGM catalysts both theoretically and experimentally,developed these into the atomically dispersed coordinated metal-nitrogen-carbon(M-N-C)form over the past *** this review,we present a comprehensive summary of recent advancements on NPGM catalysts with high activity and *** design strategies in terms of optimizing active-site density and enhancing catalyst stability against demetalization and carbon corrosion are *** is also emphasized the importance of understanding the mechanisms and principles behind those strategies through a combination of theoretical modeling and experimental ***,further understanding the mechanisms related to the active-site structure and the formation process of the single-atom active site under pyrolysis conditions is critical for active-site *** the active-site distance is the basic principle for improving catalyst activity through increasing the catalyst active-site *** studies for the catalyst deactivation mechanism and modeling stable active-site structures provide both mechanisms and principles to improve the NPGM catalyst ***,currently remained challenges and perspectives in the future on designing high-performance atomically dispersed NPGM catalysts toward fuel cell application are discussed.

关键词： batteries electrocatalysis energy storage and conversion fuel cells

Big Data Application Simulation Platform Design for Onboard Distributed Processing of LEO Mega-Constellation Networks

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China Communications 2024年第7期21卷 334-345页

作者： Zhang Zhikai Gu Shushi Zhang Qinyu Xue Jiayin School of Electronics and information Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China Guangdong Provincial Key Laboratory of aerospace Communication and Networking Technology Shenzhen 518055China Broadband Communications Research Department Peng Cheng LaboratoryShenzhen 518000China

Due to the restricted satellite payloads in LEO mega-constellation networks(LMCNs),remote sensing image analysis,online learning and other big data services desirably need onboard distributed processing(OBDP).In existing technologies,the efficiency of big data applications(BDAs)in distributed systems hinges on the stable-state and low-latency links between worker ***,LMCNs with high-dynamic nodes and long-distance links can not provide the above conditions,which makes the performance of OBDP hard to be intuitively *** bridge this gap,a multidimensional simulation platform is indispensable that can simulate the network environment of LMCNs and put BDAs in it for performance *** STK's APIs and parallel computing framework,we achieve real-time simulation for thousands of satellite nodes,which are mapped as application nodes through software defined network(SDN)and container *** elaborate the architecture and mechanism of the simulation platform,and take the Starlink and Hadoop as realistic examples for *** results indicate that LMCNs have dynamic end-to-end latency which fluctuates periodically with the constellation *** to ground data center networks(GDCNs),LMCNs deteriorate the computing and storage job throughput,which can be alleviated by the utilization of erasure codes and data flow scheduling of worker nodes.

关键词： big data application Hadoop LEO mega-constellation multidimensional simulation onboard distributed processing

Engineering hierarchical quaternary superstructure of an integrated MOF-derived electrode for boosting urea electrooxidation assisted water electrolysis

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Green Energy & Environment 2024年第4期9卷 695-701页

作者： Jianjun Tian Changsheng Cao Yingchun He Muhammad Imran Khan Xin-Tao Wu Qi-Long Zhu State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of Sciences(CAS)Fuzhou350002China Fujian Science&Technology innovation Laboratory for Optoelectronic information of China Fuzhou350108China University of Chinese Academy of Sciences Beijing100049China Research institute of Sciences and Engineering(RISE) University of SharjahSharjah27272United Arab Emirates

Controllable design of the catalytic electrodes with hierarchical superstructures is expected to improve their electrochemical ***,a self-supported integrated electrode(NiCo-ZLDH/NF)with a unique hierarchical quaternary superstructure was fabricated through a self-sacrificing template strategy from the metal–organic framework(Co-ZIF-67)nanoplate arrays,which features an intriguing well-defined hierarchy when taking the unit cells of the NiCo-based layered double hydroxide(NiCo-LDH)as the primary structure,the ultrathin LDH nanoneedles as the secondary structure,the mesoscale hollow plates of the LDH nanoneedle arrays as the tertiary structure,and the macroscale three-dimensional frames of the plate arrays as the quaternary ***,the distinctive structure of NiCo-ZLDH/NF can not only accelerate both mass and charge transfer,but also expose plentiful accessible active sites with high intrinsic activity,endowing it with an excellent electrochemical performance for urea oxidation reaction(UOR).Specially,it only required the low potentials of 1.335,1.368 and 1.388 V to deliver the current densities of 10,100 and 200 mA cm^(-2),respectively,much superior to those for typical *** NiCo-ZLDH/NF as the bifunctional electrode for both anodic UOR and cathodic HER,an energy-saving electrolysis system was further explored which can greatly reduce the needed voltage of 213 mV to deliver the current density of 100 mA cm^(-2),as compared to the conventional water electrolysis system composed of *** work manifests that it is prospective to explore the hierarchically nanostructured electrodes and the innovative electrolytic technologies for high-efficiency electrocatalysis.

关键词： Hierarchical superstructures Metal–organic frameworks Layered double hydroxides Urea oxidation reaction Hydrogen evolution reaction

Equalization Reconstruction Algorithm Based on Reference Signal Frequency Domain Block Joint for DTMB-Based Passive Radar

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Journal of Beijing institute of Technology 2024年第1期33卷 41-53页

作者： Shuai Ma Zeqi Yang Hua Zhang Yiheng Liu Xiaode Lyu aerospace information Research institute Chinese Academy of SciencesBeijing 100094China National Key Laboratory of Microwave Imaging Technology Beijing 100190China School of Electronic Electrical and Communication Engineering University of Chinese Academy of SciencesBeijing 100049China.

Channel equalization plays a pivotal role within the reconstruction phase of passive radar reference *** the context of reconstructing digital terrestrial multimedia broadcasting(DTMB)signals for low-slow-small(LSS)target detection,a novel frequency domain block joint equalization algorithm is presented in this *** the DTMB signal frame structure and channel multipath transmission characteristics,this article adopts a unconventional approach where the delay and frame structure of each DTMB signal frame are reconfigured to create a circular convolution block,facilitating concurrent fast Fourier transform(FFT)*** equalization,an inverse fast Fourier transform(IFFT)-based joint output and subsequent data reordering are executed to finalize the equalization process for the DTMB *** and measured data confirm that this algorithm outperforms conventional techniques by reducing signal errors rate and enhancing real-time *** passive radar LSS detection,it effectively suppresses multipath and noise through frequency domain equalization,reducing false alarms and improving the capabilities of weak target detection.

关键词： passive radar frequency domain equalization reference signal reconstruction digital terrestrial multimedia broadcasting(DTMB)