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Earth and planetary physics 2024年第2期8卷 408-414页

作者： Jun Wu Jian Wu Jie Feng QingLiang Li ShuJi Hao ZhengWen xu HaiSheng Zhao YaBin Zhang National Key Laboratory of Electromagnetic Environment China Research Institute of Radio Wave PropagationBeijing 102206China School of physics Xidian UniversityXi’an 710071China

During the course of ionospheric heating experiments, researchers at the European Incoherent Scatter Scientific Association (EISCAT) observed an apparent electron density enhancement. The enhancement extended over a wide range of altitudes, above the reflection altitude of the high-frequency pump wave. However, whether this enhancement actually corresponds to a true enhancement in electron density remains an open question. When the dispersion relation of ion acoustic waves is followed, the frequency ratio of the enhanced ion line to the background ion line suggests that the profile of the effective ion mass may have remained unchanged. Furthermore, the solar radio flux and ion drift velocity indicate no significant changes in the ion species and their densities. In conclusion, the electron density enhancement observed at EISCAT should not, in fact, be considered a true enhancement.

关键词： incoherent scatter radar(ISR) ionospheric heating electron density ion acoustic wave

High photoelectric conversion efficiency and fast relaxation time of FA_(0.4)MA_(0.6)pbI_(3) applied in ultrafast modulation of terahertz waves

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Journal of Energy Chemistry 2024年第4期91卷 299-305页

作者： Zhibo xu Ying Zeng Xinran Zhao Xiaoyin Chen Aoyu Fan Furi Ling Jiang Li Jianquan Yao School of Optics and Electronic Information Huazhong University of Science and TechnologyWuhan 430074HubeiChina College of precision Instrument and Optoelectronics Engineering Tianjin UniversityTianjin 300072China institute of Fluid physics China Academy of Engineering PhysicsMianyang 621900SichuanChina School of Information Engineering Wuhan University of TechnologyWuhan 430070HubeiChina National Engineering Research Center of Fiber Optic Sensing Technology and Networks Wuhan University of TechnologyWuhan 430070HubeiChina Hubei Key Laboratory of Broadband Wireless Communication and Sensor Networks Wuhan 430070HubeiChina

Active control of terahertz(THz)waves is attracting tremendous attentions in terahertz communications and active photonic ***,due to its excellent photoelectric conversion performance and simple manufacturing process,has emerged as a promising candidate for optoelectronic ***,the exploration of perovskites in optically controlled THz modulators is still *** this work,the photoelectric properties and carrier dynamics of FA_(0.4)MA_(0.6)pbI_(3)perovskite films were investigated by optical pumped terahertz probe(OpTp)*** ultrafast carrier dynamics reveal that FA_(0.4)MA_(0.6)pbI_(3)thin film exhibits rapid switching and relaxation time within picosecond level,suggesting that FA_(0.4)MA_(0.6)pbI_(3)is an ideal candidate for active THz devices with ultrafast ***,as a proof of concept,a FA_(0.4)MA_(0.6)pbI_(3)-based metadevice with integrating plasma-induced transparency(pIT)effect was fabricated to achieve ultrafast modulation of THz *** experimental results demonstrated that the switching time of FA_(0.4)MA_(0.6)pbI_(3)-based THz modulator is near to 3.5 ps,and the threshold of optical pump is as low as 12.7μJ cm^(-2).The simulation results attribute the mechanism of ultrafast THz modulation to photo-induced free carriers in the FA_(0.4)MA_(0.6)pbI_(3)layer,which progressively shorten the capacitive gap of pIT *** study not only illuminates the potential of FA_(0.4)MA_(0.6)pbI_(3)in THz modulation,but also contributes to the field of ultrafast photonic devices.

关键词： Terahertz modulation perovskites Metamaterials plasmon-induced transparency

Solid-state NMR study of the stability of MOR framework aluminum

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Chinese Journal of Structural Chemistry 2024年第4期43卷 7-14页

作者： Xinzhi Ding Chong Liu Jing Niu Nan Chen Shutao xu Yingxu Wei Zhongmin Liu National Engineering Research Center of Lower-Carbon Catalysis Technology Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian116023China State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian116023China University of Chinese Academy of Sciences Beijing 100049China School of Chemistry Dalian University of TechnologyDalian116024China

MOR zeolite has been effectively utilized for dimethyl ether(DME)carbonylation reaction due to its unique pore structure and *** industrial production,the transformation of ammonium type MOR zeolite(NH_(4)-MOR)into proton type MOR zeolite(H-MOR)causes inevitable ***,understanding the influencing factors and dynamic evolution mechanism of zeolite dealumination is *** this work,the stability of framework aluminum was studied by X-ray diffraction(XRD),Fourier transform infrared(FT-IR)spectroscopy,^(29)Si,^(27)Al,^(1)H magic angle spinning nuclear magnetic resonance(MAS NMR),and DME carbonylation performance *** results indicate that extra-framework cation Na^(+)and NH_(4)^(+)could better preserve the aluminum structure of the MOR zeolite framework compared to H^(+),primarily due to the different'attraction'of the framework to ***,the impact of water on the zeolite framework aluminum at high temperature was studied by manipulating the humidity of the calcination atmosphere,revealing the formation of extra-framework six-coordinated aluminum(Al(Ⅵ)-EF)and the mechanism of water influence on the zeolite framework aluminum.

关键词： H-MOR Solid-state NMR H2O Framework aluminum stability Dealumination

New Dispersed phase of Electrorheological Fluids:TiO_2 Coating Graphite particles

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Journal of Materials Science & Technology 2000年第5期16卷 529-530页

作者： Sujuan xu+ and Biao WANG (Harbin institute of Technology, Harbin 150001, China) Shouqiang MEN and Kunquan LU (institute of physics, Chinese Academy of Sciences, Beijing 100080, China) Harbin institute of Technology Harbin 150001 China institute of physics Chinese Academy of Sciences Beijing 100080 China

We have prepared novel coated particles, with a conductor graphite core and a dielectric TiO2 coating, as the dispersed phase of electrorheological fluids. One order of magnitude enhancement in the shear stress is obtained by using such composite particles, when it is compared with that of TiO2 particles. The experimental results show a way to get excellent ER system.

关键词： New Dispersed phase of Electrorheological Fluids Graphite TiO

Kinetic energy and charge state effects in the X-ray emission of Mo surface induced by Xe^(q+)(q=25,29) ions

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Science China(physics,Mechanics & Astronomy) 2008年第9期51卷 1240-1244页

作者： CUI Ying1,YANG ShengSheng2,YANG ZhiHu3,xu JinZhang1,ZHANG HongQiang1,xu xu1,SHAO JianXiong1,LIU ZhaoYuan1,XIAO GuoQing3,ZHANG XiaoAn4,ZHAO YongTao3,ZHANG Yanping3 & CHEN XiMeng1 1 Department of modern physics,Lanzhou University,Lanzhou 730000,China 2 National Key Laboratory of Vacuum & Cryogenics Technology and physics,Lanzhou 730000,China 3 institute of modern physics,Chinese Academy of Sciences,Lanzhou 730000,China 4 Normal College of Xianyang,Xianyang 713000,China Department of modern physics Lanzhou University Lanzhou China National Key Laboratory of Vacuum & Cryogenics Technology and physics Lanzhou China institute of modern physics Chinese Academy of Sciences Lanzhou China Normal College of Xianyang Xianyang China

L-shell X-ray spectra of Mo surface induced by Xe25+ and Xe29+ were measured. The X-ray intensity was obtained in the kinetic energy range of the incident ions from 350 to 600 keV. The relationship of X-ray intensity ... 详细信息

关键词： X-ray surface kinetic energy and charge state effect Xeq+

Improvement of cloud microphysical parameterization and its advantages in simulating precipitation along the Sichuan-Xizang Railway

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Science China Earth Sciences 2024年第3期67卷 856-873页

作者： Xiaoqi xu Zhiwei HENG Yueqing LI Shunjiu WANG Jian LI Yuan WANG Jinghua CHEN peiwen ZHANG Chunsong LU China Meteorological Administration Transportation Meteorology Key Laboratory Nanjing Joint Institute for Atmospheric SciencesNanjing 210041China Heavy Rain and Drought-Flood Disasters in plateau and Basin Key Laboratory of Sichuan province Institute of Plateau MeteorologyCMAChengdu 610072China State Key Laboratory of Disaster Weather Chinese Academy of Meteorological SciencesBeijing 100081China Collaborative Innovation Center for Western Ecological Safety Lanzhou UniversityLanzhou 730000China China Meteorological Administration Aerosol-Cloud and precipitation Key Laboratory and Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD) Nanjing University of Information Science and TechnologyNanjing 210044China

The Sichuan-Xizang Railway is an important part of the railway network in China, and geological disasters, such as mountain floods and landslides, frequently occur in this region. precipitation is an important cause of these disasters;therefore,accurate simulation of the precipitation in this region is highly important. In this study, the descriptions for uncertain processes in the cloud microphysics scheme are improved;these processes include cloud droplet activation, cloud-rain autoconversion, rain accretion by cloud droplets, and the entrainment-mixing process. In the default scheme, the cloud water content of different sizes corresponds to the same cloud droplet concentration, which is inconsistent with the actual content;this results in excessive cloud droplet size, unreasonable related conversion rates of microphysical process(such as cloud-rain autoconversion), and an overestimation of precipitation. Our new scheme overcomes the problem of excessive cloud droplet size. The processes of cloudrain autoconversion and rain accretion by cloud droplets are similar to the stochastic collection equation, and the mixing mechanism of cloud droplets is more consistent with that occurred during the actual physical process in the cloud. Based on the new and old schemes, multiple precipitation processes in the flood season of 2021 along the Sichuan-Xizang Railway are simulated, and the results are evaluated using ground observations and satellite data. Compared to the default scheme, the new scheme is more suitable for the simulation of cloud physics, reducing the simulation deviation of the liquid water path and droplet radius from 2 times to less than 1 time and significantly alleviating the overestimation of precipitation intensity and range of precipitation center. The average root-mean-square error is reduced by 22%. Our results can provide a scientific reference for improving precipitation forecasting and disaster prevention in this region.

关键词： The Sichuan-Xizang Railway Cloud microphysics precipitation Model improvement

Geant4 simulation of fast-electron bremsstrahlung imaging at the HL-3 tokamak

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Nuclear Science and Techniques 2024年第9期35卷 213-229页

作者： Shi-Kui Cheng Yi-po Zhang Yue-Jiang Shi Jie Zhang Shuai Guan Hong-Bing xu Qiu-Lei Yang College of Science Chongqing University of TechnologyChongqing 400054China Chongqing Key Laboratory of New Energy Storage Materials and Devices Chongqing 400054China Southwestern institute of physics Chengdu 610041China Hebei Key Laboratory of Compact Fusion Langfang 065001China ENN Science and Technology Development Co. Ltd.Langfang 065001China

To further research on high-parameter plasma,we plan to develop a two-dimensional hard X-ray(HXR)imaging system at the HL-3 tokamak to measure HXRs with energies ranging from 20 to 300 *** application of an array-structured detector ensures that this system can measure HXR-radiation spectra from the entire plasma cross ***,it is suitable for the study of fast-electron physics,such as radio-frequency wave current drives,fast electrons driving instabilities,and plasma disruptions in fusion *** this study,we develop a simulation for calculating fast-electron bremsstrahlung in the HL-3 tokamak based on the Monte Carlo simulation code Geant4,in which the plasma geometry and forward scattering of fast-electron bremsstrahlung are *** preliminary calculation results indicate that the HXR energy deposi-tion on the detector is symmetrically distributed,even though the plasma distribution is asymmetric owing to the toroidal *** simulation results are helpful in constructing the relationship between the energy deposition on the detector and parameter distribution on the plasma cross section during HL-3 *** is beneficial for the reconstruction of the fast-electron-distribution function and for optimizing the design of the HXR-imaging system.

关键词： Geant4 simulation HL-3 tokamak Fast-electron bremsstrahlung Hard X-ray imaging

Efficient second and third harmonic generation in dual-layer lithium niobate microdisk resonator

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Science China(physics,Mechanics & Astronomy) 2024年第5期67卷 33-38页

作者： Zhenzhong Hao Xiao Wu Qiang Luo Zhang Li Rui Ma Fang Bo Feng Gao Guoquan Zhang Jingjun xu MOE Key Laboratory of Weak-Light Nonlinear photonics TEDA Institute of Applied Physics and School of PhysicsNankai UniversityTianjin 300457China

Lithium niobate thin film frequency doubler has extensive applications in the preparation of classical and quantum *** this study,we successfully fabricated microdisk resonators with a quality factor of 2.2×10^(5) in reverse-polarization dual-layer x-cut lithium niobate for the first *** on the modal phase matching condition,efficient second harmonic generation with a record normalized conversion efficiency of~56000%W-1 and cascaded third harmonic generation with an efficiency of~6500%W-2 were obtained in the microdisk *** with the periodically poled lithium niobate microcavity,the complex domain structure preparation processes are *** work provides a scheme for achieving highly efficient second-order nonlinear effects in non-periodically poled microcavities.

关键词： harmonic lithium niobate

High strength mullite-bond SiC porous ceramics fabricated by digital light processing

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Journal of Advanced Ceramics 2024年第1期13卷 53-62页

作者： Jian Sun Jingde Zhang xu Zhang Zihe Li Jianzhang Li Sijie Wei Weibin Zhang Weili Wang Guifang Han Key Laboratory for Liquid-Solid Structural Evolution and processing of Materials(Ministry of Education) School of Materials Science and EngineeringShandong UniversityJinan 250061China Key Laboratory of Special Functional Aggregated Materials Ministry of EducationShandong UniversityJinan 250100China Materials and Structures Research Centre Department of Mechanical EngineeringUniversity of BathBath BA27AYUK National Engineering Research Centre of Ceramic Matrix Composite Manufacture Technology Xi’an Golden Mountain Ceramic Composites Co.Ltd.Xi’an 710118China School of physics and Materials Science Changji UniversityChangji 831100China

Fabricating SiC ceramics via the digital light processing(DLp)technology is of great challenge due to strong light absorption and high refractive index of deep-colored SiC powders,which highly differ from those of resin,and thus significantly affect the curing performance of the photosensitive SiC *** this paper,a thin silicon oxide(SiO_(2))layer was in-situ formed on the surface of SiC powders by pre-oxidation *** method was proven to effectively improve the curing ability of SiC *** SiC photosensitive slurry was fabricated with solid content of 55 vol%and viscosity of 7.77 pa·s(shear rate of 30 s^(−1)).The curing thickness was 50μm with exposure time of only 5 ***,a well-designed sintering additive was added to completely convert low-strength SiO_(2) into mullite reinforcement during *** mullite-bond SiC ceramics were successfully *** flexural strength of SiC ceramics sintered at 1550℃in air reached 97.6 Mpa with porosity of 39.2 vol%,as high as those prepared by spark plasma sintering(SpS)techniques.

关键词： digital light processing(DLp) SiC ceramics pre-oxidation mullite-bond SiC mechanical properties

Aerodynamic Super-Repellent Surfaces

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Research 2024年第2期2023卷 115-122页

作者： Fanfei Yu Jinlong Yang Ran Tao Yao Tan Jinpei Wang Dehui Wang Longquan Chen Zuankai Wang xu Deng institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu 610054P.R.China Department of Mechanical Engineering City University of Hong KongKowloonHong Kong Special Administrative Region 999077P.R.China School of physics.University of Electronic Science and Technology of China Chengdu 610054P.R.China Department of Mechanical Engineering Hong Kong Polytechnic UniversityKowloonHong Kong Special Administrative Region 999077P.R.China Shenzhen institute for Advanced Study University of Electronic Science and Technology of ChinaShenzhen 518110P.R.China

Repelling liquid drops from engineering surfaces has attracted great attention in a variety of *** achieve efficient liquid shedding,delicate surface textures are often introduced to sustain air pockets at the liquid-solid ***,those surfaces are prone to suffer from mechanical failure,which may bring reliability issues and thus limits their ***,inspired by the aerodynamic Leidenfrost effect,we present that impacting drops are directionally repelled from smooth surfaces supplied with an exogenous air *** theoretical analysis reveals that the synchronized nonwetting and oblique bouncing behavior is attributed to the aerodynamic force arising from the air *** versatility and practicability of our approach allow for drop repellency without the aid of any surface wettability treatment and also avoid the consideration of mechanical stability issues,which thereby provides a promising candidate for the applications that necessitate liquid shedding,e.g.,resolve the problem of tiny raindrop adhesion on the automobile side window during driving.

关键词： thereby driving attributed