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Surface shape detection methods for large radio telescopes
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作者 Zhengxiong Sun Jinqing Wang +7 位作者 linfeng yu Yongchen Jiang Zheng Lou Yongbin Jiang Rongbin Zhao Qian Ye Qinghui Liu Guangli Wang 《Astronomical Techniques and Instruments》 CSCD 2024年第5期275-283,共9页
The surface accuracy of a radio telescope is directly related to its operational efficiency and detection sensitivity.This is crucial under high-frequency observation conditions,where surface shape errors need to be c... The surface accuracy of a radio telescope is directly related to its operational efficiency and detection sensitivity.This is crucial under high-frequency observation conditions,where surface shape errors need to be controlled to within 1/16 of the working wavelength.In addition,the primary reflector of large radio telescopes is subject to dynamic deformation,caused by factors such as gravity and thermal effects.This paper presents a method for detecting the surface shape of radio telescopes using radio interferometry techniques combined with active reflector adjustment technology.This enables accurate assessment and correction of surface errors,ensuring the electrical performance of the radio telescope.This study investigates the practical applications of high-precision measurement techniques,such as microwave holography,out-of-focus holography,and wavefront distortion methods at the Tianma 65 m radio telescope(TMRT).Furthermore,the study presents the construction method of gravity models at different elevation angles and demonstrates the efficacy of the active reflector model.The results of the measurements indicate that the application of these methods to the TMRT has led to a notable enhancement of the accuracy of the primary reflector and a substantial improvement in efficiency in the Q-band.Through a process of iterative measurements and adjustments,the surface shape error is ultimately reduced to 0.28 mm root mean square(RMS). 展开更多
关键词 Radio telescope Holographic measurements Surface shape measurements Antenna efficiency
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Combining WV-2 images and tree physiological factors to detect damage stages of Populus gansuensis by Asian longhorned beetle (Anoplophora glabripennis) at the tree level 被引量:3
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作者 Quan Zhou Xudong Zhang +2 位作者 linfeng yu Lili Ren Youqing Luo 《Forest Ecosystems》 SCIE CSCD 2021年第3期479-490,共12页
Background:Anoplophora glabripennis(Motschulsky),commonly known as Asian longhorned beetle(ALB),is a wood-boring insect that can cause lethal infestation to multiple borer leaf trees.In Gansu Province,northwest China,... Background:Anoplophora glabripennis(Motschulsky),commonly known as Asian longhorned beetle(ALB),is a wood-boring insect that can cause lethal infestation to multiple borer leaf trees.In Gansu Province,northwest China,ALB has caused a large number of deaths of a local tree species Populus gansuensis.The damaged area belongs to Gobi desert where every single tree is artificially planted and is extremely difficult to cultivate.Therefore,the monitoring of the ALB infestation at the individual tree level in the landscape is necessary.Moreover,the determination of an abnormal phenotype that can be obtained directly from remote-sensing images to predict the damage degree can greatly reduce the cost of field investigation and management.Methods:Multispectral WorldView-2(WV-2)images and 5 tree physiological factors were collected as experimental materials.One-way ANOVA of the tree’s physiological factors helped in determining the phenotype to predict damage degrees.The original bands of WV-2 and derived vegetation indices were used as reference data to construct the dataset of a prediction model.Variance inflation factor and stepwise regression analyses were used to eliminate collinearity and redundancy.Finally,three machine learning algorithms,i.e.,Random Forest(RF),Support Vector Machine(SVM),Classification And Regression Tree(CART),were applied and compared to find the best classifier for predicting the damage stage of individual P.gansuensis.Results:The confusion matrix of RF achieved the highest overall classification accuracy(86.2%)and the highest Kappa index value(0.804),indicating the potential of using WV-2 imaging to accurately detect damage stages of individual trees.In addition,the canopy color was found to be positively correlated with P.gansuensis’damage stages.Conclusions:A novel method was developed by combining WV-2 and tree physiological index for semi-automatic classification of three damage stages of P.gansuensis infested with ALB.The canopy color was determined as an abnormal phenotype that could be directly assessed using remote-sensing images at the tree level to predict the damage degree.These tools are highly applicable for driving quick and effective measures to reduce damage to pure poplar forests in Gansu Province,China. 展开更多
关键词 Worldview-2 Anoplophora glabripennis Populus gansuensis INFESTATION Degree of damage Canopy color Classification
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On-chip stimulated Brillouin scattering[Invited] 被引量:1
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作者 余林峰 黄楚坤 +4 位作者 程铭 王康 石浩天 黄强 孙军强 《Chinese Optics Letters》 SCIE EI CAS CSCD 2024年第2期28-41,共14页
On-chip stimulated Brillouin scattering(SBS)has attracted extensive attention by introducing acousto-optic coupling interactions in all-optical signal processing systems.A series of chip-level applications such as Bri... On-chip stimulated Brillouin scattering(SBS)has attracted extensive attention by introducing acousto-optic coupling interactions in all-optical signal processing systems.A series of chip-level applications such as Brillouin lasers,amplifiers,gyroscopes,filters,and nonreciprocal devices are realized based on Brillouin acousto-optic interaction.Here,we first introduce the fundamental principle of SBS in integrated photonics and a method for calculating Brillouin gain;then we illustrate the Brillouin effect on different material platforms with diverse applications.Finally,we make a concise conclusion and offer prospects on the future developments of on-chip SBS. 展开更多
关键词 stimulated Brillouin scattering integrated photonics SILICON-ON-INSULATOR
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应用于天线测量的实时硬件相关处理机设计
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作者 韦钰 王锦清 +3 位作者 卜朝晖 张磊 虞林峰 江永琛 《建模与仿真》 2024年第3期2857-2867,共11页
天线的指向测量和面形测量对于航天工程和深空探测具有重要意义,而相关机是天线指向精度测量最主要的设备之一。本文设计了一套适用于天线指向和面形测量的高性能实时硬件相关机,与常规的相关机相比,它实现了整数比特和小数比特补偿,同... 天线的指向测量和面形测量对于航天工程和深空探测具有重要意义,而相关机是天线指向精度测量最主要的设备之一。本文设计了一套适用于天线指向和面形测量的高性能实时硬件相关机,与常规的相关机相比,它实现了整数比特和小数比特补偿,同时实现了条纹旋转,用于补偿几何延迟和多普勒频率偏差,具有高比特采样量化能力,可以同时兼顾卫星信号和射电源信号作为测量信号输入,适用于多通道干涉测量天线指向和面形误差。干涉法测量天线指向偏差,相比于单天线测量,可以提高检测灵敏度,增加可检测源的数量。本文通过对该相关机进行理论研究与分析,建立了硬件相关机模型,对相关机的整数和小数比特时延补偿、条纹旋转、积分四个主要模块的功能进行仿真测试,仿真结果与理论值之间具有很好的一致性,充分验证了该硬件相关处理机设计的正确性。 展开更多
关键词 干涉法 硬件相关机 天线测量
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Sourcing the merits of 3D integrated air cathodes for highperformance Zn-air batteries by bubble pump consumption chronoamperometry
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作者 Mengxuan Li linfeng yu +4 位作者 Hai Liu Chuanyi Zhang Jiazhan Li Liang Luo Xiaoming Sun 《Nano Research》 SCIE EI CSCD 2024年第8期6951-6959,共9页
Zn-air batteries(ZABs)as a potential energy conversion system suffer from low power density(typically≤200 mW·cm^(−2)).Recently,three-dimensional(3D)integrated air cathodes have demonstrated promising performance... Zn-air batteries(ZABs)as a potential energy conversion system suffer from low power density(typically≤200 mW·cm^(−2)).Recently,three-dimensional(3D)integrated air cathodes have demonstrated promising performance over traditional twodimensional(2D)plane ones,which is ascribed to enriched active sites and enhanced diffusion,but without experimental evidence.Herein,we applied a bubble pump consumption chronoamperometry(BPCC)method to quantitatively identify the gas diffusion coefficient(D)and effective catalytic sites density(ρEC)of the integrated air cathodes for ZABs.Furthermore,the D andρEC values can instruct consequent optimization on the growth of Co embedded N-doped carbon nanotubes(CoNCNTs)on carbon fiber paper(CFP)and aerophilicity tuning,giving 4 times D and 1.3 timesρEC over the conventional 2D Pt/C-CFP counterparts.As a result,using the CoNCNTs with half-wave potential of merely 0.78 V vs.RHE(Pt/C:0.89 V vs.RHE),the superaerophilic CoNCNTs-CFP cathode-based ZABs exhibited a superior peak power density of 245 mW·cm^(−2) over traditional 2D Pt/C-CFP counterparts,breaking the threshold of 200 mW·cm^(−2).This work reveals the intrinsic feature of the 3D integrated air cathodes by yielding exact D andρEC values,and demonstrates the feasibility of BPCC method for the optimization of integrated electrodes,bypassing trial-and-error strategy. 展开更多
关键词 Zn-air batteries three-dimensional(3D)integrated air cathodes superaerophilic gas diffusion coefficient effective catalytic sites density
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π-Extended End Groups Enable High-Performance All-Polymer Solar Cells with Near-Infrared Absorption 被引量:1
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作者 linfeng yu Haiqin Xiao +4 位作者 yu Shi Xia Guo Xinxin Xia Xinhui Lu Maojie Zhang 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2023年第23期3261-3267,共7页
Narrow-bandgap n-type polymers are essential for advancing the development of all-polymer solar cells(all-PSCs).Herein,we developed a novel polymer acceptor PNT withπ-extended 2-(3-oxo-2,3-dihydro-1H-cyclopenta[b]nap... Narrow-bandgap n-type polymers are essential for advancing the development of all-polymer solar cells(all-PSCs).Herein,we developed a novel polymer acceptor PNT withπ-extended 2-(3-oxo-2,3-dihydro-1H-cyclopenta[b]naphthalen-1-ylidene)malononitrile(CPNM)end groups.Compared to commonly used 2-(3-oxo-2,3-dihydro-1H-cyclopenta[b]naphthalen-1ylidene)malononitrile(IC)units,CPNM units have a further extended fused ring,providing the PNT polymer with extended absorption into the near-IR region(903 nm)and exhibiting a narrow optical bandgap(1.37 eV).Furthermore,PNT exhibits a high electron mobility(6.79×10^(−4) cm^(2)·V^(−1)·S^(−1))and a relatively high-lying lowest unoccupied molecular orbital(LUMO)energy level of−3.80 eV.When blended with PBDB-T,all-PSC achieves a power conversion efficiency(PCE)of 13.7%and a high short-circuit current density(JSC)of 24.4 mA·cm^(−2),mainly attributed to broad absorption(600—900 nm)and efficient charge separation and collection.Our study provides a promising polymer acceptor for all-PSCs and demonstrates thatπ-extended CPNM units are important to achieve high-performance for all-PSCs. 展开更多
关键词 Polymer acceptors π-Extended end groups High short-circuit current density Narrow-bandgap All-polymer solar cells
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An asymmetric non-fused electron-deficient building block for low-cost polymer acceptor in all-polymer solar cells
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作者 Haiqin Xiao linfeng yu +5 位作者 Zhiliang Zhang Haiyan Liang yu Shi Xia Guo Maojie Zhang Yongfang Li 《Science China Chemistry》 SCIE EI CAS CSCD 2023年第9期2626-2633,共8页
The development of polymerized fused-ring small molecule acceptors(FRA-PAs) has boosted the performance of all-polymer solar cells(all-PSCs).However,these FRA-PAs suffer from lengthy synthesis steps and high productio... The development of polymerized fused-ring small molecule acceptors(FRA-PAs) has boosted the performance of all-polymer solar cells(all-PSCs).However,these FRA-PAs suffer from lengthy synthesis steps and high production costs due to the high degree of synthetic complexity for fused-ring small molecule acceptors(FRAs).Furthermore,most FRA-PAs exhibit strong batch-to-batch variation,limiting further industrial applications.Herein,we designed and synthesized asymmetric non-fused electron-deficient building block TIC-Br with a simple structure(only three synthetic steps),showing a planar configuration,excellent electron affinity,and large dipole moment.A simple polymer acceptor PTIB was further developed by polymerization of TIC-Br and sensitized fluorinated-thienyl benzodithiophene(BDT-TF-Sn).PTIB exhibits a broad absorption from 300 to 800 nm,a suitable lowest unoccupied molecular orbital(LUMO) energy level of-3.86 e V,and moderate electron mobility(1.02×10^(-4)cm^(2)V^(-1)s^(-1)).When matched with PM6,the device achieved the best PCE of 10.11%with a high V_(OC) of 0.97 V,which is one of the highest among those reported all-PSCs.More importantly,PTIB exhibits a lower synthetic complexity index(SC=35.0%)and higher figure-of-merit values(FOM=29.0%) than all the reported high-performance PAs.The polymer also exhibits excellent batch-to-batch reproducibility and great potential for scale-up fabrication.This study indicates that TIC-Br is a promising building block for constructing low-cost polymer acceptors for large-scale applications in all-PSCs. 展开更多
关键词 non-fused electron-deficient building block low-cost polymer acceptors batch-to-batch reproducibility all-polymer solar cells
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Boosting Plasmonic Hot Electron Utilization for Visible-Light Photocatalysis Using Polarized Ag-TiO_(2) Nanoparticles
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作者 Yonglong Li linfeng yu +4 位作者 Ying Wang Cancan Zhang Yangxuan Gao Teng Wang Wei Xie 《CCS Chemistry》 CSCD 2023年第8期1908-1916,共9页
Plasmonic hot electrons have long been regarded as a promising energy source for inducing chemical transformations.However,because of the mismatch between the electron cloud of reactant molecules and the hot-electron ... Plasmonic hot electrons have long been regarded as a promising energy source for inducing chemical transformations.However,because of the mismatch between the electron cloud of reactant molecules and the hot-electron gas of metal nanoparticles(NPs),the highly localized and short-lived hot electrons are dif-ficult to utilize in bulk synthesis when the reactant molecules do not have a strong affinity for the metal surface.Here,we propose the concept of polarized nanocatalysts to mimic chemical polarity at the nanometer scale.Under plasmonic photorecycling conditions,the rationally designed asymmetric Ag-TiO_(2) hybrid NPs enable six-electron reduction of molecules in bulk solution.This hot-electron-driven reaction does not require a conventional hydrogen or hydride reducing agent.As a proof-of-concept,one-pot photocatalytic syntheses of amides,such as paracetamol,using nitro reactants were performed.This provides a new opportunity to enable challenging multielectron transformations in organic chemistry. 展开更多
关键词 plasmonic catalysis polarized nanoparticles hot electrons multielectron transfer amide synthesis
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