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5G Wideband Bandpass Filtering Power Amplifiers Based on a Bandwidth-Extended Bandpass Matching Network

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China Communications 2023年第11期20卷 56-66页

作者： weimin wang Hongmin Zhao Yongle Wu Xiaopan Chen School of Electronic Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China School of Integrated Circuits Beijing University of Posts and TelecommunicationsBeijing 100876China

In this paper,a 5G wideband power amplifier(PA)with bandpass filtering response is synthesized using a bandwidth-extended bandpass filter as the matching network(MN).In this structure,the bandwidth(θ_(C))is defined as a variable in the closedform equations provided by the microstrip bandpass filter.It can be extended over a wide range only by changing the characteristic impedances of the structure.Different from the other wideband MNs,the extension of bandwidth does not increase the complexity of the structure(order n is fixed).In addition,based on the bandwidth-extended structure,the wideband design of bandpass filtering PA is not limited to the fixed bandwidth of the specific filter structure.The theoretical analysis of the MN and the design flow of the PA are provided in this design.The fabricated bandpass filtering PA can support almost one-octave bandwidth(2-3.8 GHz),covering the two 5G bands(n41 and n78).The drain efficiency of 47%-60%and output power higher than 40 dBm are measured.Good frequency selectivity in S-parameter measurements can be observed.

关键词： bandpass filtering bandwidth-extension fixed order power amplifier wideband

On Dynamic Channel Emulation in Sector MPAC for Over-the-Air Testing of Beamformed Massive MIMO Devices

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China Communications 2023年第4期20卷 41-56页

作者： Xiaochen Chen Heng wang weimin wang Zheng Liu Yuanan Liu China Academy of Information and Communications Technology Beijing 100191China Beijing Key Laboratory of Work Safety Intelligent Monitoring Department of Electronic EngineeringBeijing University of Posts and TelecommunicationsBeijing 100876China

In this article,novel emulation strategies for the sectored multiple probe anechoic chamber(SMPAC)are proposed to enable the reliable evaluation of the massive multiple-input multiple-output(MIMO)device operating at beamforming mode,which requires a realistic non-stationary channel environment.For the dynamic propagation emulation,an efficient closed-form probe weighting strategy minimizing the power angular spectrum(PAS)emulation errors is derived,substantially reducing the associated computational complexity.On the other hand,a novel probe selection algorithm is proposed to reproduce a more accurate fading environment.Various standard channel models and setup configurations are comprehensively simulated to validate the capacity of the proposed methods.The simulation results show that more competent active probes are selected with the proposed method compared to the conventional algorithms.Furthermore,the derived closedform probe weighting strategy offers identical accuracy to that obtained with complicated numerical optimization.Moreover,a realistic dynamic channel measured in an indoor environment is reconstructed with the developed methodologies,and 95.6%PAS similarity can be achieved with 6 active probes.The satisfactory results demonstrate that the proposed algorithms are suitable for arbitrary channel emulation.

关键词： beamforming channel emulation massive MIMO device multiple probe anechoic chamber(MPAC) over-the-air testing

Virtual source approach for maximizing resolution in high-penetration gamma-ray imaging

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Matter and Radiation at Extremes 2024年第3期9卷 19-30页

作者： Yuchi Wu Shaoyi wang Bin Zhu Yonghong Yan Minghai Yu Gang Li Xiaohui Zhang Yue Yang Fang Tan Feng Lu Bi Bi Xiaoqin Mao Zhonghai wang Zongqing Zhao Jingqin Su weimin Zhou Yuqiu Gu National Key Laboratory of Plasma Physics Laser Fusion Research CenterCAEPMianyangSichuan 621900China College of Physics Sichuan UniversityChengdu 610065China

High-energy gamma-ray radiography has exceptional penetration ability and has become an indispensable nondestructive testing(NDT)tool in various fields.For high-energy photons,point projection radiography is almost the only feasible imaging method,and its spatial resolution is primarily constrained by the size of the gamma-ray source.In conventional industrial applications,gamma-ray sources are commonly based on electron beams driven by accelerators,utilizing the process of bremsstrahlung radiation.The size of the gamma-ray source is dependent on the dimensional characteristics of the electron beam.Extensive research has been conducted on various advanced accelerator technologies that have the potential to greatly improve spatial resolution in NDT.In our investigation of laser-driven gamma-ray sources,a spatial resolution of about 90μm is achieved when the areal density of the penetrated object is 120 g/cm^(2).A virtual source approach is proposed to optimize the size of the gamma-ray source used for imaging,with the aim of maximizing spatial resolution.In this virtual source approach,the gamma ray can be considered as being emitted from a virtual source within the convertor,where the equivalent gamma-ray source size in imaging is much smaller than the actual emission area.On the basis of Monte Carlo simulations,we derive a set of evaluation formulas for virtual source scale and gamma-ray emission angle.Under optimal conditions,the virtual source size can be as small as 15μm,which can significantly improve the spatial resolution of high-penetration imaging to less than 50μm.

关键词： resolution approach utilizing

Single-Layer Symmetrical Full-Port Quasi-Absorptive Filtering Phase Shifter

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China Communications 2023年第12期20卷 30-40页

作者： Qingxiang Dong Yongle Wu Weijuan Chen Yuhao Yang weimin wang School of Integrated Circuits Beijing University of Posts and TelecommunicationsBeijing 100876China School of Electronic Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China

In this article,a single-layer symmetrical full-port quasi-absorptive filtering phase shifter is presented.The proposed phase shifter is composed of a main quasi-absorptive filtering branch,a reference quasi-absorptive filtering branch,and two delay lines.The proposed phase shifter achieves both phase controlling function and quasi-absorptive filtering function for the first time.Each quasi-absorptive filtering branch can realize the quasi-absorptive filtering function.Meanwhile,the constant phase shift can be obtained by combining the two quasi-absorptive filtering branches and the two delay lines.The design formulas can be derived from the even-and odd-mode network analysis,and then two quasi-absorptive filtering phase shifters can be devised easily and quickly.For verification,a 90°quasi-absorptive filtering phase shifter,which is critical for circularly polarized antenna systems,is simulated,manufactured,and measured.

关键词： filtering phase shifter(PS) quasiabsorptive reflectionless symmetrical

Multi-probe linear fitting and time of arrival linear correction method to analyze blade vibration based on blade tip timing without once-per-revolution

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Chinese Journal of Aeronautics 2023年第1期36卷 290-310页

作者： Sanqun REN Xiaorong XIANG Qingjun ZHAO weimin wang Wei ZHAO Chuanlin ZHAN Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing 100049China Innovation Academy for Light-duty Gas Turbine Chinese Academy of SciencesBeijing 100190China Beijing University of Chemical Technology Beijing 100029China

Blade vibration monitoring can ensure the safe operation of aeroengine rotor blades.Among the methods of blade vibration monitoring,Blade Tip Timing(BTT)method has attracted more and more attention because of its advantages of non-contact measurement.However,it is difficult to install the Once-Per-Revolution(OPR)probe in the confined space of aeroengine,and the failure and instability of the OPR signal will reduce the reliability of the blade vibration analysis results,which directly affects the accuracy of the blade vibration parameters identification.The Multi-Probe linear fitting and Time of Arrival(ToA)Linear Correction method based on the BTT(MP-LC-BTT)without OPR is proposed to reduce the errors of single probe linear fitting method for blade vibration displacement analysis.The proposed method can also correct the calculation error of blade vibration displacement due to the nonlinear change of rotation speed,which can improve the analysis accuracy of the blade vibration displacement.A new blade vibration model conforming to the actual vibration characteristics is established,and the effectiveness of the proposed method is verified by numerical simulation.Finally,the reliability and accuracy of the MP-LC-BTT method have been verified by the experiments which include two high-speed blade test-benches and an industrial axial fan.This method can be used in the actual aero-engine monitoring instead of the BTT method with OPR.

关键词： Blade Tip Timing(BTT) Linear correction Multi-probe linear fitting Once-Per-Revolution(OPR) Rotor blades Vibration analysis

Grain-refining fabrication of nanocrystalline(La_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Eu_(0.2))_(2)Zr_(2)O_(7)high-entropy ceramics by ultra-high pressure sintering

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Journal of Materials Science & Technology 2023年第36期167卷 205-212页

作者： Zhangtian Wu Wei Ji Jinyong Zhang Yanan Yuan Ji Zou weimin wang Zhengyi Fu State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Hubei Longzhong Laboratory Wuhan University of Technology Xiangyang Demonstration ZoneXiangyang 441000China

As an important A_(2)B_(2)O_(7)-type ceramic,(La_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Eu_(0.2))_(2)Zr_(2)O_(7)high-entropy pyrochlore pos-sesses promising properties such as high melting point,high chemical durability,and low thermal conductivity.However,the low sintering ability limits its application in thermal barrier coating and radioactive waste immobilization.It usually needs long-term high-temperature soaking to achieve full density,but with inevitable grain growth.In this work,dense and grain-refined nanocrystalline(La_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Eu_(0.2))_(2)Zr_(2)O_(7)ceramics were prepared with ultra-high pressure sintering(UHPS)method under 10 GPa at a low temperature of 800℃.The densification behavior,microstructure evo-lution,and properties of the UHPS-ed samples were then investigated.The grain size of as-prepared(La_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Eu_(0.2))_(2)Zr_(2)O_(7)ceramic was only 151 nm,which is 40%smaller than that of raw pow-der.In addition,it exhibited advantageous properties including both high hardness and aqueous durabil-ity.Plastic deformation under ultra-high pressure was believed as the dominant densification mechanism responsible for grain refinement and property improvement.

关键词： High-entropy ceramics Ultra-high pressure sintering Grain refining Nanocrystalline Plastic deformation

Titanium nitrides as novel reactants for in-situ synthesis of TiB_(2)-based composites with improved properties

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Journal of Materials Science & Technology 2023年第14期145卷 48-55页

作者： Ji Zou Huayue Liang Jingjing Liu weimin wang Fan Zhang Wei Ji Zhengyi Fu State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Hubei Longzhong Laboratory Xiangyang 441000China School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China

A novel in-situ reactive approach based on the reactions among TiN,aluminum and boron has been developed to synthesize TiB_(2)-based composites including TiB_(2)-h BN(TB)and TiB_(2)-h BN-AlN(TBA).Fully dense ceramics with fine-grained microstructure were successfully obtained via spark plasma sintering at 1850℃/60 MPa/5 min.Microstructure analysis suggests h BN flakes were homogenously distributed in the TiB_(2)matrix.For AlN,however,they were elongated into plate-like grains during sintering,in which lots of defects in terms of stacking faults and twinning structures were observed.The mechanical and thermophysical properties of as-sintered ceramics were comprehensively investigated and compared.In-corporating AlN significantly improved the flexure strength,hardness,fracture toughness and thermal conductivity of TiB_(2)-h BN ceramics.The electrical conductivity of TB(3.06×10^(6)S/m)is larger than that of TBA(2.35×10^(6)S/m)at room temperature,but the value(6×10^(5)S/m)was lower than that of TBA(6.9×10^(5)S/m)at 1173 K.Based on the measurement of electrical and thermal conductivity,electron and phonon contributions to thermal conductivities of TB and TBA were calculated and their temperature dependences were illustrated.

关键词： Borides Microstructure Spark plasma sintering Mechanical property Thermo-physics property

Bio-inspired high-efficiency photosystem by synergistic effects of core-shell structured Au@CdS nanoparticles and their engineered location on{001}facets of SrTiO_(3)nanocrystals

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Journal of Materials Science & Technology 2023年第5期136卷 159-168页

作者： Wenxuan wang Wenhao Chi Zhaoyong Zou Pengchao Zhang Kun wang Ji Zou Hang Ping Jingjing Xie weimin wang Zhengyi Fu State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Hubei Longzhong Laboratory Xiangyang 441000China State Key Laboratory of Silicate Materials for Architectures Wuhan University of TechnologyWuhan 430070China

Natural photosynthesis,which provides a green and high-efficiency energy conversion path by spatial separation of photogenerated carriers through combined actions of molecules ingeniously arranged in an efficient solar nanospace,highlights the importance of rational nanostructure design to realize artificial high-efficiency photosystem.Inspired by these unique features,we constructed a high-efficiency ternary photosystem by selectively decorating the{001}facets of 18-facet SrTiO_(3)with Au@CdS photosensitizers via a green photo-assisted method.Benefiting from the dual-facilitated charge carriers transportation in core-shell structured Au@CdS heterojunction and well-faceted 18-facet SrTiO_(3)nanocrystal,such a photo-catalyst could realize the effective spatial separation of photogenerated electrons and holes.As expected,the 18-facet SrTiO_(3)/Au@CdS photocatalyst exhibits superior activity in visible-light-driven photocatalytic hydrogen evolution(4.61 mmol h^(−1)g^(−1)),166%improvement in comparison with randomly deposited Au@CdS(1.73 mmol h^(−1)g^(−1)).This work offers new insight into the development of green and high-efficiency photocatalytic systems based on the rational nanostructure design by crystal facet engineering.

关键词： Au@CdS composites Core-shell 18-facet SrTiO_(3) Photogenerated carrier separation Crystal facet engineering Hydrogen production

Analysis of Influencing Factors on Fruit Consumption of Urban and Rural Residents in Beijing

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Asian Agricultural Research 2024年第6期16卷 1-4,10页

作者： Zihao wang Rao CHEN weimin YANG College of Economics and Management Beijing University of AgricultureBeijing 102206China Beijing Research Center of Rural Revitalization Beijing 102206China Department of Basic Education Beijing University of AgricultureBeijing 102206China

In light of the rapid expansion of China s economy,there has been a notable shift in the consumption patterns of urban and rural residents.This is evident in the increased consumption of agricultural products,with fruit consumption representing a particularly pronounced trend.The 2023 Beijing Consumption Statistics indicate that demand for fruit is increasing,accompanied by heightened competition for quality and brands.The paper is based on research that examines the current situation of fruit consumption among urban and rural residents in Beijing.The results indicate that when urban and rural residents in Beijing purchase fruits,price is the most significant factor influencing fruit consumption.Taste,appearance,and variety are also considered to be important influencing factors,while the influence of factors such as fruit type,consumption pattern,and fruit brand is relatively minor.

关键词： Urban and rural residents of Beijing Fruit consumption Influencing factor Consumption behavior