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Phase-field simulations of the effect of temperature and interface for zirconiumδ-hydrides

Chinese physics B 2024年第4期33卷 701-710页

作者：陈子航盛杰刘瑜施小明黄厚兵许可王越超武帅孙博刘海风宋海峰 School of Materials science and Engineering Beijing Institute of TechnologyBeijing 100081China Advanced Research Institute of Multidisciplinary science Beijing Institute of TechnologyBeijing 100081China Laboratory of Computational physics Institute of Applied Physics and Computational MathematicsBeijing 100088China department of physics University of Science and Technology BeijingBeijing 100083China

Hydride precipitation in zirconium cladding materials can damage their integrity and *** temperature and material defects have a significant effect on the dynamic growth of *** this study,we have developed a phasefield model based on the assumption of elastic behaviour within a specific temperature range(613 K-653 K).This model allows us to study the influence of temperature and interfacial effects on the morphology,stress,and average growth rate of zirconium *** results suggest that changes in temperature and interfacial energy influence the length-to-thickness ratio and average growth rate of the hydride *** ultimate determinant of hydride orientation is the loss of interfacial coherency,primarily induced by interfacial dislocation defects and quantifiable by the mismatch degree *** escalation in interfacial coherency loss leads to a transition of hydride growth from horizontal to vertical,accompanied by the onset of redirection ***,redirection occurs at a critical mismatch level,denoted as qc,and remains unaffected by variations in temperature and interfacial ***,this redirection leads to an increase in the maximum stress,which may influence the direction of hydride crack *** research highlights the importance of interfacial coherency and provides valuable insights into the morphology and growth kinetics of hydrides in zirconium alloys.

关键词： zirconium hydride phase-field method temperature effect mismatch degree

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Hollow cathode effect in radio frequency hollow electrode discharge in argon

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Chinese physics B 2024年第3期33卷 496-502页

作者：贺柳良何锋欧阳吉庭 College of science Beijing University of Civil Engineering and ArchitectureBeijing 102616China School of physics Beijing Institute of TechnologyBeijing 100081China

Radio frequency capacitively coupled plasma source(RF-CCP)with a hollow electrode can increase the electron density through the hollow cathode effect(HCE),which offers a method to modify the spatial profiles of the plasma *** this work,the variations of the HCE in one RF period are investigated by using a two-dimensional particle-in-cell/Monte-Carlo collision(PIC/MCC)*** results show that the sheath electric field,the sheath potential drop,the sheath thickness,the radial plasma bulk width,the electron energy distribution function(EEDF),and the average electron energy in the cavity vary in one RF *** the hollow electrode sheath's expansion phase,the secondary electron heating and sheath oscillation heating in the cavity are gradually enhanced,and the frequency of the electron pendular motion in the cavity gradually increases,hence the HCE is gradually ***,during the hollow electrode sheath's collapse phase,the secondary electron heating is gradually *** addition,when interacting with the gradually collapsed hollow electrode sheaths,high-energy plasma bulk electrons in the cavity will lose some ***,the frequency of the electron pendular motion in the cavity gradually ***,during the hollow electrode sheath's collapse phase,the HCE is gradually attenuated.

关键词： hollow cathode effect radio frequency hollow electrode particle-in-cell/Monte-Carlo collision(PIC/MCC)model

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Anisotropic tribology and electrification properties of slidingmode triboelectric nanogenerator with groove textures

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Friction 2024年第8期12卷 1828-1837页

作者： Weixu YANG Jieyang WANG Xiaoli WANG Ping CHEN department of Mechanical Engineering University of Science and Technology BeijingBeijing 100083China department of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China

Sliding-mode triboelectric nanogenerator(S-TENG)is based on the coupling of triboelectrification and electrostatic induction,converting electrical energy from sliding *** micro-textures into the sliding surface,and adjusting the angle between the texture and sliding direction(direction angle)may achieve performance anisotropy,which provides novel ideas for optimizing the tribology and electrification performance of *** guide the performance optimization based on the anisotropy,in this paper,groove micro-textures were fabricated on the surface of S-TENG,and anisotropic tribology and electrification performance were obtained through changing the direction *** on the surface analysis and after-cleaning tests,the mechanism of the anisotropy was *** is shown that the anisotropy of friction coefficient can be attributed to the changes of texture edge induced resistance and groove captured wear debris,while the voltage anisotropy is due to the variations of debris accumulated on the sliding interface and the resulting charge *** the selected 0°–90°direction angles,S-TENG at angle of 90°exhibits relatively small stable friction coefficient and high open-circuit voltage,and thus it is recommended for the performance *** open-circuit voltage is not directly associated with the friction coefficient,but closely related to the wear debris accumulated on the sliding *** study presents a simple and convenient method to optimize the performance of S-TENG,and help understand the correlation between its tribology and electrical performance.

关键词： sliding-mode triboelectric nanogenerator groove textures direction angle performance anisotropy tribology&electrification properties

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Effects of the initiation position on the damage and fracture characteristics of linear-charge blasting in rock

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International Journal of Minerals,Metallurgy and Materials 2024年第3期31卷 443-451页

作者： Chenxi Ding Renshu Yang Xiao Guo Zhe Sui Chenglong Xiao Liyun Yang School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China School of Mechanics and Civil Engineering China University of Mining and Technology(Beijing)Beijing 100083China School of Mathematics and physics University of Science and Technology BeijingBeijing 100083China State Key Lab of Explosion science and technology Beijing Institute of TechnologyBeijing 100081China

To study the effects of the initiation position on the damage and fracture characteristics of linear-charge blasting, blasting model experiments were conducted in this study using computed tomography scanning and three-dimensional reconstruction methods. The fractal damage theory was used to quantify the crack distribution and damage degree of sandstone specimens after blasting. The results showed that regardless of an inverse or top initiation, due to compression deformation and sliding frictional resistance, the plugging medium of the borehole is effective. The energy of the explosive gas near the top of the borehole is consumed. This affects the effective crushing of rocks near the top of the borehole, where the extent of damage to Sections Ⅰ and Ⅱ is less than that of Sections Ⅲ and Ⅳ. In addition, the analysis revealed that under conditions of top initiation, the reflected tensile damage of the rock at the free face of the top of the borehole and the compression deformation of the plug and friction consume more blasting energy, resulting in lower blasting energy efficiency for top initiation. As a result, the overall damage degree of the specimens in the top-initiation group was significantly smaller than that in the inverse-initiation group. Under conditions of inverse initiation, the blasting energy efficiency is greater, causing the specimen to experience greater damage. Therefore, in the engineering practice of rock tunnel cut blasting, to utilize blasting energy effectively and enhance the effects of rock fragmentation, using the inverse-initiation method is recommended. In addition, in three-dimensional(3D) rock blasting, the bottom of the borehole has obvious end effects under the conditions of inverse initiation, and the crack distribution at the bottom of the borehole is trumpet-shaped. The occurrence of an end effect in the 3D linear-charge blasting model experiment is related to the initiation position and the blocking condition.

关键词： blasting linear charge initiation position computed tomography three-dimensional reconstruction damage

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Influence of erosion voids and traffic loads on buried large-diameter reinforced concrete pipes

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Underground Space 2024年第4期17卷 120-131页

作者： Ming Xu Dawei Shen department of Civil Engineering Tsinghua UniversityBeijing 100084China beijing Institute of technology Beijing 100081China

Geotechnical centrifuge tests were conducted to examine the influence of invert voids and surface traffic loads on 1400 mm diameter reinforced concrete pipes buried with a shallow soil cover depth of 700 *** formation beneath the pipe was simulated during centrifuge *** test results revealed that before void formation,the surface load directly above the middle of the pipe caused a significant increase in not only the circumferential bending moments but also the longitudinal bending moments,the latter of which was considerable and could not be *** formation beneath the middle of the pipe led to a reduction in both the circumferential bending moments and longitudinal bending moments at all measuring positions,i.e.,crown,springline,and *** most significant reduction occurred at the invert,and there was even a reversal in the sign of the invert longitudinal bending moment.A comparison was made between centrifuge tests with erosion voids and surface loads at different horizontal positions,which had a marked influence even when the positions differed by half a pipe *** rotation played an important role in relieving large bending moments of pipe barrels in a jointed pipeline when the void and surface load were located at the joint.

关键词： Centrifuge test Erosion void Reinforced concrete pipe Traffic loading Longitudinal bending moment Joint rotation

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Plasma density enhancement in radio-frequency hollow electrode discharge

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Plasma science and technology 2024年第4期26卷 44-51页

作者：贺柳良何锋欧阳吉庭 College of science Beijing University of Civil Engineering and ArchitectureBeijing 102616People’s Republic of China School of physics Beijing Institute of TechnologyBeijing 100081People’s Republic of China

The plasma density enhancement outside hollow electrodes in capacitively coupled radio-frequency(RF) discharges is investigated by a two-dimensional(2D) particle-in-cell/Monte-Carlo collision(PIC/MCC) model. Results show that plasma exists inside the cavity when the sheath inside the hollow electrode hole is fully collapsed, which is an essential condition for the plasma density enhancement outside hollow electrodes. In addition, the existence of the electron density peak at the orifice is generated via the hollow cathode effect(HCE), which plays an important role in the density enhancement. It is also found that the radial width of bulk plasma at the orifice affects the magnitude of the density enhancement, and narrow radial plasma bulk width at the orifice is not beneficial to obtain high-density plasma outside hollow *** electron density at the orifice, combined with larger radial plasma bulk width at the orifice,causes higher electron density outside hollow electrodes. The results also imply that the HCE strength inside the cavity cannot be determined by the magnitude of the electron density outside hollow electrodes.

关键词： RF capacitively coupled plasma sources plasma density enhancement hollow cathodeeffect hollow electrode

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A post-modification strategy to precisely construct dual-atom sites for oxygen reduction electrocatalysis

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Journal of Energy Chemistry 2024年第3期90卷 511-517,I0012页

作者： Juan Wang Xinyan Liu Chang-Xin Zhao Yun-Wei Song Jia-Ning Liu Xi-Yao Li Chen-Xi Bi Xin Wan Jianglan Shui Hong-Jie Peng Bo-Quan Li Jia-Qi Huang School of Materials science and Engineering Beijing Institute of TechnologyBeijing 100081China Advanced Research Institute of Multidisciplinary science Beijing Institute of TechnologyBeijing 100081China beijing Key Laboratory of Green Chemical Reaction Engineering and technology Department of Chemical EngineeringTsinghua UniversityBeijing 100084China Institute of Fundamental and Frontier sciences University of Electronic Science and Technology of ChinaChengdu 611731SichuanChina School of Materials science and Engineering Beihang UniversityBeijing 100191China

Dual-atom catalysts(DACs) afford promising potential for oxygen reduction electrocatalysis due to their high atomic efficiency and high intrinsic ***,precise construction of dual-atom sites remains a *** this work,a post-modification strategy is proposed to precisely fabricate DACs for oxygen reduction ***,a secondary metal precursor is introduced to the primary single-atom sites to introduce direct metal-metal interaction,which ensures the formation of desired atom pair structure during the subsequent pyrolysis process and allows for successful construction of *** as-prepared FeCo-NC DAC exhibits superior oxygen reduction electrocatalytic activity with a half-wave potential of 0,91 V *** hydrogen ***-air batteries equipped with the FeCo-NC DAC demonstrate higher peak power density than those with the Pt/C *** importantly,this post-modification strategy is demonstrated universal to achieve a variety of dual-atom *** work presents an effective synthesis methodology for precise construction of catalytic materials and propels their applications in energy-related devices.

关键词： Dual-atom catalysts Electrocatalysis Oxygen reduction reaction Post-modification Zinc–air batteries

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In Situ Atomic Reconstruction Engineering Modulating Graphene-Like MXene-Based Multifunctional Electromagnetic Devices Covering Multi-Spectrum

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Nano-Micro Letters 2024年第9期16卷 247-261页

作者： Ting‑Ting Liu Qi Zheng Wen‑Qiang Cao Yu‑Ze Wang Min Zhang Quan‑Liang Zhao Mao‑Sheng Cao School of Materials science and Engineering Beijing Institute of TechnologyBeijing 100081People’s Republic of China department of physics Beijing Technology and Business UniversityBeijing 100048People’s Republic of China School of Mechanical and Materials Engineering North China University of TechnologyBeijing 100144People’s Republic of China

With the diversified development of big data,detection and precision guidance technologies,electromagnetic(EM)functional materials and devices serving multiple spectrums have become a hot *** the multispectral response of materials is a challenging and meaningful scientific *** this study,MXene/TiO_(2)hybrids with tunable conduction loss and polarization relaxation are fabricated by in situ atomic reconstruction *** importantly,MXene/TiO_(2)hybrids exhibit adjustable spectral responses in the GHz,infrared and visible spectrums,and several EM devices are constructed based on *** antenna array provides excellent EM energy harvesting in multiple microwave bands,with|S11|up to−63.2 dB,and can be tuned by the degree of *** ultra-wideband bandpass filter realizes a passband of about 5.4 GHz and effectively suppresses the transmission of EM signals in the *** infrared stealth device has an emissivity of less than 0.2 in the infrared spectrum at wavelengths of 6-14μ*** work can provide new inspiration for the design and development of multifunctional,multi-spectrum EM devices.

关键词： Graphene-like MXene hybrids Multi-spectral response Multi-function antenna Ultra-wideband bandpass filter Electromagnetic device

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Scaling laws governing the elastic properties of 3D graphenes

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science china(Technological sciences) 2024年第6期67卷 1748-1756页

作者： LI Ming LU Guo YU HaoDong LI MengLei ZHENG FaWei Centre for Quantum physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement(MOE)School of PhysicsBeijing Institute of TechnologyBeijing100081China beijing Key Lab of Nanophotonics&Ultrafine Optoelectronic Systems School of PhysicsBeijing Institute of TechnologyBeijing100081China Laboratory of Computational physics Institute of Applied Physics and Computational MathematicsBeijing100088China department of physics Capital Normal UniversityBeijing100048China

In this study,we comprehensively investigated the scaling law for elastic properties of three-dimensional honeycomb-like graphenes(3D graphenes)using hybrid neural network potential-based molecular dynamics simulations and theoretical *** elastic constants were obtained as functions of honeycomb hole size,denoted by the graphene wall length *** five independent elastic constants in the large-L limit are proportional to L^(-1).The associated coefficients are combinations of elastic constants of two-dimensional ***-order terms including L^(-2)and L^(-3)emerge for finite L *** have three origins,the distorted areas close to the joint lines of 3D graphenes,the variation in solid angles between graphene plates,and the bending distortion of graphene ***,the chirality becomes essential with decreasing L because the joint line structures are different between the armchair and zigzag-type 3D *** findings provide insights into the elastic properties of graphene-based superstructures and can be used for further studies on graphene-based materials.

关键词： scaling law neural network elastic properties 3D graphene

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Multidimensional hollow SiO_(2)/C nanofibers modified by magnetic nanocrystals for electromagnetic energy conversion and lithium battery storage

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Nano Research 2024年第8期17卷 7301-7314页

作者： Chen Han Qi Zheng Juncheng Jin Jiajia Zhang Wen-Qiang Cao Kun Xiang Min Zhang Mao-Sheng Cao Anhui Provincial Laboratory of Biomimetic Sensor and Detecting technology College of Materials and Chemical EngineeringWest Anhui UniversityLu’an 237012China School of Materials science and Engineering Beijing Institute of TechnologyBeijing 100081China department of physics Beijing Technology and Business UniversityBeijing 100048China

Multifunctional materials are powerful tools to support the advancement of energy conversion *** with prominent electromagnetic and electrochemical properties can realize the conversion of electromagnetic energy and solve the subsequent storage ***,an electrospinning-thermal reduction method is employed to construct ultrafine nickel nanoparticle modified porous SiO_(2)/C(Ni-SiO_(2)/C)hollow nanofibers as promising materials for applications in both electromagnetic wave absorption(EMA)and lithium-ion ***,when used as an EMA material,the reflection loss(RL)of Ni-SiO_(2)/C can reach−47.8 dB at 15.8 GHz with a matching thickness of 2.2 *** excellent microwave absorption performance can be attributed to the enhanced conduction loss,polarization relaxation,synergistic magnetic loss,and preferred impedance matching,which result from multi-component magnetic/dielectric synergy and the unique interconnected multidimensional hollow ***,the electronic conductivity and electrochemical activity of the samples are significantly enhanced due to the uniform distribution of ultrafine Ni nanoparticles in the amorphous SiO_(2)/C ***,the hierarchical hollow porous structure provides sufficient free space for volume change during lithiation/delithiation ***,the Ni-SiO_(2)/C nanocomposite exhibits a high reversible capacity of 917.6 mAh·g^(−1)at 0.1 A·g^(−1).At a high current density of 2 A·g^(−1),a capacity of 563.9 mAh·g^(−1)can be maintained after 300 *** energy conversion-storage device is designed to store waste electromagnetic energy in the form of useful electrical *** work inspires the development of high-performance bifunctional materials.

关键词： Ni-SiO_(2)/C nanofiber electromagnetic absorption lithium-ion storage electrospinning multidimensional structure

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