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Science China(Technological Sciences) 2024年第6期67卷 1923-1932页

作者： ZHAO Tao SHI Yan LU Kun XI Xiang wu XueZhong xiao DingBang College of Intelligence Science and Engineering National University of Defense TechnologyChangsha410073China

The quality factor(Q factor)is a crucial performance parameter for *** this paper,a novel release method for highquality micro fused silica shell resonators with teeth-like tines with good surface morphology is *** method is based on femtosecond laser-assisted chemical ***,the optimal energy range of femtosecond laser modification is obtained through mechanism ***,the optimal parameters for a straight line and arc pattern are determined by optimizing the average output power,processing speed,and processing *** results demonstrate why edge breakage in rounded corners is easy under different ***,according to these conclusions,the processing is performed on a micro fused silica shell resonator with a Q factor exceeding 6 *** addition,subsurface damage is rare throughout the fabrication process,and the surface roughness of the released cross section reaches the nanometer *** improved Q factor helps suppress mechanical thermal noise and reduce zero bias and zero bias drift,constituting the primary method for enhancing the performance of the resonant gyroscope.

关键词： micro hemispherical resonator fused silica laser-assisted chemical etching quality factor

Climatic impacts induced by winter wheat irrigation over North China simulated by the nonhydrostatic RegCM4.7

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Advances in Climate Change Research 2024年第2期15卷 197-210页

作者： Jia wu Zhen-Yu HAN Xue-Jie gao Zheng-Jia LIU National Climate Centre China Meteorological AdministrationBeijing 100081China Key Laboratory for Climate Studies China Meteorological AdministrationBeijing 100081China Climate Change Research Center Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjing 210044China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China

Quantification of the impact of winter wheat irrigation on the climate and the occurrence of extreme climatic events over North China is crucial for regional adaptation *** related studies mainly focused on the impact on surface processes;however,few focused on the effects of extreme events using high-resolution nonhydrostatic regional climate ***,the 9-km-resolution nonhydrostatic RegCM4.7 was coupled with a crop irrigation scheme and an updated winter wheat irrigation dataset to better simulate irrigation *** experiments were conducted with and without winter wheat irrigation to isolate the effects of *** showed that irrigation simulation reduces the model biases in temperature,precipitation,latent heat flux,soil moisture,sensitive heat flux,and top-layer soil ***,it also reduces the bias and increases the correlation with observations obtained in irrigated areas,especially in summer,indicating better representation of irrigation *** wheat irrigation tends to cause substantial cooling of the local surface maximum,minimum,and mean air temperatures(by-1.68,-0.34,and-0.79℃,respectively)over irrigated areas of North China,with the largest changes observed in relation to maximum ***,precipitation is found to increase during spring and summer,which is strongly related to water vapor transport in the lower levels of the *** analyses indicated that the number of annual mean hot days decrease(-13.9 d),whereas the number of both comfort days(+10.2 d)and rainy days(days with total precipitation greater than 1 mm:+6.6 d)increase over irrigated areas,demonstrating beneficial feedback to human perception and ***,although the heat wave risk increases(number of annual mean heat wave days:+5.8 d),the impact is limited to small areas within irrigated ***,no notable change was found in terms of heavy rainfall events and precipitation intensity

关键词： Nonhydrostatic regional climate model Irrigation effect Extreme events North China

Influence of oxygen-rich hot air composite gas medium on sintering performance and function mechanism

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Journal of Iron and Steel Research International 2024年第5期31卷 1071-1081页

作者： Min Gan Hao-xiang Zheng xiao-hui Fan Zhi-yun Ji Qiang Li Ming wu Yi-fan Wang xiao-long Wang Yu-feng wu Xu-ling Chen Zeng-qing Sun xiao-xian Huang School of Minerals Processing and Bioengineering Central South UniversityChangsha410083HunanChina Shanxi Taigang Stainless Steel Co. Ltd.Taiyuan030003ShanxiChina

Hot air sintering technology is used to improve the quality and production efficiency of sintered ***,the current thick layer condition highlights the disadvantage of the low oxygen potential of the hot air sintering ***,it is considered to use oxygen enrichment sintering to improve the environment of hot air *** sintering,hot air sintering,and oxygen-rich hot air sintering were compared through sintering cup experiments,and the influence of hot air and oxygen-rich hot air on sintering indexes was *** air reduced the vertical sintering velocity,while improved the yield and tumbler ***-rich hot air sintering contributed to improving the vertical sintering velocity while ensuring the quality of sintered ore,thus comprehensively improving production *** the action of hot air,the highest temperature of the sintering layer increased and the high-temperature holding time was *** oxygen enrichment,the combustion efficiency of fuels in the upper layer of materials was promoted,which optimized heat distribution in the middle and lower layers of materials and increased the content of calcium ferrite in the sintered ore,thus strengthening the sintering process.

关键词： Iron ore sintering Hot air sintering Oxygen enrichment Function mechanism

Investigation on the Novel High-performance Copper/Graphene Composite Conductor for High Power Density Motor

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CES Transactions on Electrical Machines and Systems 2024年第1期8卷 80-85页

作者： Jiaxiao Wang Tingting Zuo Jiangli Xue Yadong Ru Yue wu Zhuang Xu Yongsheng Liu Zhaoshun gao Puqi Ning Tao Fan Xuhui Wen Li Han Liye xiao Shanghai University of Electric Power Shanghai 200090Chinaand the Institute of Electrical EngineeringChinese Academy of SciencesShanghai 200090China the Institute of Electrical Engineering Chinese Academy of SciencesBeijing 100190China with Shanghai University of Electric Power Shanghai 200090China

High-performance Cu/Graphene composite wire synergistically strengthened by nano Cr_(3)C_(2) phase was directly synthesized via hot press sintering followed by severe cold plastic deformation, using liquid paraffin and CuCr alloy powder as the raw materials. Since graphene is in situ formed under the catalysis of copper powder during the sintering process, the problem that graphene is easy to agglomerate and difficult to disperse uniformly in the copper matrix has been solved. The nano Cr_(3)C_(2)-particles nailed at the interface favor to improve the interface bonding. The Cu/Graphene composite possesses high electrical conductivity, hardness, and plasticity. The composite wire exhibits high electrical conductivity of 96.93% IACS, great tensile strength of 488MPa, and excellent resistance to softening. Even after annealing at 400℃ for 1 h, the tensile strength can still reach 268 MPa with a conductivity of about 99.14% *** wire's temperature coefficient of resistance(TCR) is largely reduced to 0.0035/℃ due to the complex structure,which leads the wire to present low resistivity at higher temperatures. Such Cu/Graphene composite wire with excellent comprehensive performance has a good application prospect in high-power density motors.

关键词： Cu/Graphene composite Mechanical properties Electrical property Microstructure Temperature coefficient of resistance

Asymptotic normality of error density estimator in stationary and explosive autoregressive models

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Applied Mathematics(A Journal of Chinese Universities) 2024年第1期39卷 140-158页

作者： wu Shi-peng YANG Wen-zhi gao Min HU Shu-he School of Mathematical Sciences&School of Big Data and Statistics Anhui UniversityHefei 230601China School of Statistics Shanxi University of Finance and EconomicsTaiyuan030006China

In this paper,we consider the limit distribution of the error density function estima-tor in the rst-order autoregressive models with negatively associated and positively associated random *** mild regularity assumptions,some asymptotic normality results of the residual density estimator are obtained when the autoregressive models are stationary process and explosive *** order to illustrate these results,some simulations such as con dence intervals and mean integrated square errors are provided in this *** shows that the residual density estimator can replace the density\estimator"which contains errors.

关键词： explosive autoregressive models residual density estimator asymptotic distribution association sequence

Injection of a Self-propelled Polymer into a Small Circular Cavity

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Chinese Journal of Polymer Science 2024年第6期42卷 886-894页

作者： Chao Wang Yan-Li Zhou xiao Yang Fan wu Meng-Bo Luo Department of Physics Taizhou UniversityTaizhou318000China Department of Physics Zhejiang UniversityHangzhou310027China

The injection of a polymer chain into a small circular cavity under tangential self-propelled force is studied by using Langevin dynamics *** indicate that the injection dynamics of the active polymer shows strong correlation with the polymer conformation inside the cavity depending on the polymer rigidity(k_(b)).The injection timeτvaries nonmonotonously with increasing k_(b),and reaches its minimum at k_(b)^(*).When k_(b) is small(k_(b)≪k_(b)^(*)),the polymer is nearly random coil in the cavity,and spends a long time at the final stage of the injection process due to the large repulsion between monomers inside the *** k_(b) is moderate(k_(b)∼k_(b)^(*)),the part of polymer inside the cavity forms spiral configuration under the tangential active force,and the whole polymer moves synchronously with a constant velocity during the injection process,leading to a small injection *** k_(b) is large(k_(b)≫k_(b)^(*)),the polymer is nearly straight at the initial stage of the injection process,and takes a long time to bend itself,leading to a large injection time.

关键词： Active Polymer Injection Dynamics Simulation

Development of a novel signal restoration algorithm to eliminate the distorted components in space charge measurement excited by femtosecond laser irradiation

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High Voltage 2024年第3期9卷 659-673页

作者： Tianrun Qi Hanwen Ren Haoyu gao Qingmin Li Yidan Ma Yiqun Ma Tao xiao State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijingChina

For the space charge measurement method with optical excitation for electrical insulation,the distortion of the excitation laser on the measurement signal and the accumulation of space charge have not been discussed *** experiment and simulation results show that three types of distorted components introduced by optical excitation can lead to distortion of the upper interface ***,the factors causing distortion of the measured signal and the formation mechanism are analysed.A virtual electrode potential compensation method and a distorted component extraction method are ***,an attenuation restoration and charge conversion correction factor is intro-duced,leading to a novel signal processing algorithm adapted to space charge optical measurement *** with the traditional algorithm,the novel algorithm has an error of less than 1%in the calculation of charge and electric field strength,with an increase in accuracy of 47.7%and 9.81%,*** applying the novel restoration algorithm,the comparison shows that the space charge accumulation does not change significantly under laser irradiation,verifying the reliability of the optical *** given algorithm can provide a theoretical and technical foundation for the realisation of the optical measurement method for space charge.

关键词： charge algorithm excitation

Analysis and suppression of operational overvoltage and inrush current for high-speed trains by automatic phase-switching technique

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High Voltage 2024年第3期9卷 733-748页

作者： Ye Cao Song xiao Zhizong Ye Guangning wu Yujun Guo Guoqiang gao Chuanming Sun Jiancheng Liu Zheng Chen Hao Hou Zijing Wang Puyang Liu Yuhui Zhang Jie Yu School of Electrical Engineering Southwest Jiaotong UniversityChengduChina Guangdong Power Grid Limited Liability Company China Southern Power GridGuangzhouChina CRRC Qingdao Sifang Co. Ltd.QingdaoChina State Grid Chongqing Electric Power Company ChongqingChina

When a high-speed train approaches the insulated phase-splitting section embedded between neighbouring power supply arms,the vacuum circuit breaker(VCB)installed on trains must be disconnected to maintain the traction power supply system as a no-load condition for completing phase-switching action,as the train passes through the phase-splitting section depending on its ***,when operating VCBs,the arc is easily triggered between the mobile contacts inside,accompanied by an overvoltage ***,to explore the generating mechanism of inrush current and operational overvoltage,a model describing the‘substation-catenary-train’traction power supply system is launched based on an equivalent circuit modelling *** the analysis of the transient VCB operational process,the phase of catenary voltage is directly related to the characteristics of the VCB switching-on overvoltage,as the traction cur-rent's phase angle is relevant to the amplitude-frequency characteristics of the VCB switching-off *** current as a noteworthy element is related to the traction transformer's *** automatic phase-switching technique is utilised to suppress both operational overvoltage and inrush current,as the optimal combination of VCB switching-on and switching-off phases considering the balance between overvoltage and inrush current is achieved based on the particle swarm algorithm.

关键词： traction phase inrush

A Tri-Salt Composite Electrolyte with Temperature Switch Function for Intelligently Temperature-Controlled Lithium Batteries

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Energy & Environmental Materials 2024年第6期7卷 84-93页

作者： Ende Fu Huimin Wang Yating Zhang Zhenxue xiao Xiu Zheng Shuai Hao Xueping gao Institute of New Energy Material Chemistry School of Materials Science and EngineeringNankai UniversityTianjin300350 China

The intense research of lithium-ion batteries has been motivated by their successful applications in mobile devices and electronic *** emerging of intelligent control in kinds of devices brings new requirements for battery *** high-energy lithium batteries are expected to respond or react under different environmental *** this work,a tri-salt composite electrolyte is designed with a temperature switch function for intelligently temperature-controlled lithium ***,the halide Li_(3)YBr_(6)together with LiTFSI and LiNO_(3)works as active fillers in a low-melting-point polymer matrix(polyethyleneglycol dimethyl ether(PEGDME)and polyethylene oxide(PEO)),which is further filled into the pre-lithiated alumina fiber *** 60°C,the composite electrolyte exists in the liquid state and fully contacts with the working electrodes on the liquid–solid interface,effectively minimizing the interfacial resistance and leading to high discharge capacity in the *** electrolyte is changed into a solid state below 30°C so that the ionic conductivity is significantly reduced and the interface resistance is increased dramatically on the solid–solid ***,by simply adjusting the temperature,the cell can be turned“ON”or“OFF”*** novel function of the composite electrolyte has enlightening significance in developing intelligently temperature-controlled lithium batteries.

关键词： composite electrolyte halide electrolyte low melting point solid-state battery temperature switch function

Engineering CuMn Prussian blue analog-shelled nanobox for efficient electrochemical reduction of nitrate to ammonia

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Tungsten 2024年第4期6卷 833-844页

作者： Zi-Yi Yang Yu-Dong Li Dan Liu Mao-Sen Song Yang gao Qing-Ping wu En-Shan Han Yan-Zhen He xiao-Hui Yang School of Chemical Engineering and Technology Hebei University of Technology Key Laboratory of Bio-Based Material Science and Technology Northeast Forestry University Institute of Electrochemical Energy Storage Helmholtz-Zentrum Berlin für Materialien und Energie Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences

Electrocatalytic nitrate reduction reaction（ENRR） for ammonia synthesis is a promising strategy to relieve nitration contamination,as well as an alternative to the Haber-Bosch *** blue analogs（PBAs） are expected to be an electrocatalytic material with superior performance owing to their abundant active sites and open channel ***,most reported PBA materials possess low nitrate conversion and ammonia yield rates,which has led to a hindrance in their research of ***,CuMn-PBA-shelled nanoboxes（CuMn-PBA SNBs） synthesized through tannic acid etching and cation exchange approaches are demonstrated for efficient ammonia *** optimal CuMn-PBA SNBs electrode achieves a high nitrate conversion of 91.33% and ammonia selectivity of 98.87% in a 0.2 mol·L-1Na2SO4solution with100×10-6NO3--N at-1.4 V ***,the CuMn-PBA SNB s electrode exhibits exceptional stability throughout a 30 h electrocatalytic *** outstanding electrochemical performance is attributed to the unique hollow nanobox structure with abundant active sites and high-throughput transport pathways for ions' aspects.

关键词： Acid etching Ammonia synthesis Cation exchange Electrocatalytic nitrate reduction Nanobox Prussian blue analogs