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Unveiling of Terahertz Emission from Ultrafast Demagnetization and the Anomalous Hall Effect in a Single Ferromagnetic Film

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Chinese Physics Letters 2024年第4期41卷 45-50页

作者：蓝志强李章顺徐浩然刘凡金钻明彭滟朱亦鸣 Terahertz Technology innovation research institute Terahertz Spectrum and Imaging Technology Cooperative Innovation CenterShanghai Key Lab of Modern Optical SystemUniversity of Shanghai for Science and TechnologyShanghai 200093China

Using THz emission spectroscopy,we investigate the elementary spin dynamics in ferromagnetic single-layer Fe on a sub-picosecond *** demonstrate that THz radiation changes its polarity with reversal of the magnetization applied by the external magnetic *** addition,it is found that the sign of THz polarity excited from different sides is defined by the thickness of the Fe layer and Fe/dielectric *** on the thickness and symmetry dependences of THz emission,we experimentally distinguish between the two major contributions:ultrafast demagnetization and the anomalous Hall *** experimental results not only enrich understanding of THz electromagnetic generation induced by femtosecond laser pulses but also provide a practical way to access laser-induced ultrafast spin dynamics in magnetic structures.

关键词： magnetic magnetization polarity

Recent research in mechanical properties of geopolymer-based ultrahigh-performance concrete:A review

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Defence Technology（防务技术） 2024年第2期32卷 67-88页

作者： G.Murali Division of research&innovation Uttaranchal UniversityDehradun 248007India

Due to the growing need for sustainable and ultra-high-strength construction materials,scientists have created an innovative ultra-high-performance concrete called Geopolymer based ultra-highperformance concrete(GUHPC).Besides,in the last few decades,there have been a lot of explosions and ballistic attacks around the world,which have killed many civilians and fighters in border *** this context,this article reviews the fresh state and mechanical properties of ***,the ingredients of GUHPC and fresh properties such as setting time and flowability are briefly ***,the review of compressive strength,flexure strength,tensile strength and modulus of elasticity of fibrous ***,the blast and projectile impact resistance performance was ***,the microstructural characteristics were reviewed using the scanning electron microscope and X-ray Powder *** review outcome reveals that the mechanical properties were increased when 30%silica fume was added to a higher dose of steel fibre to improve the microstructure of *** is hypothesized that the brittleness of GUHPC was mitigated by adding 1.5%steel fibre reinforcement,which played a role in the decrease of contact explosion cratering and *** the need for cement in GUHPC was a key factor in the review,indicating a promising potential for lowering carbon ***,GUHPC research is still in its early stages,so more study is required before its full potential can be utilized.

关键词： Mechanical properties Blast Projectile impact Fibre Geopolymer Silica fume Alkaline activators

Cerium refinement of grains and primary carbides during solidification of Cr_(4)Mo_(4)V bearing steel

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Journal of Rare Earths 2024年第4期42卷 783-792页

作者： Weifeng Liu Jianqiang Wang Mingyue Sun Bin Xu Jiahao Yao Qunbo Fan Dianzhong Li Chongqing innovation Center Beijing Institute of TechnologyChongqing401135China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

The effect of cerium(Ce)on the solidification microstructure of Cr_(4)Mo_(4)V bearing steel was investigated via a combined experimental and theoretical *** a trace amount(0.056 wt%)of Ce addition,the coarse columnar grains in as-cast microstructure transform into equiaxed ones,and the average diameter is reduced from 56 to 27μ*** network-like and bulky primary MC and M2C carbides at the interdendritic regions become disconnected and refined,and their volume percentage decreases from4.15 vol%to 2.1 vol%.Ce-inclusions acting as heterogeneous nucleation agents of prior-austenite grains and Ce atoms segregating at grain boundaries,both contribute to the refinement of *** calculations reveal that primary carbides are precipitated afterγ-austenite forms near the end of the solidification *** modification of primary carbides in size and amount is mainly attributed to the isolated remaining melt separated by refinedγ-austenite grains in which the nucleation of carbides is promoted,while the growth is restrained owing to the less segregation of alloying elements.

关键词： Cr_(4)Mo_(4)V bearing steel Rare Earths Grains Primary carbides Refinement

Lattice Boltzmann simulation study of anode degradation in solid oxide fuel cells during the initial aging process

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International Journal of Minerals,Metallurgy and Materials 2024年第2期31卷 405-411页

作者： Shixue Liu Zhijing Liu Shuxing Zhang Hao Wu Hydrogen Energy Industrial Technology innovation Center China Nuclear Power Technology Research InstituteShenzhen 518031China Shenzhen Engineering research Center for Hydrogen Safety Shenzhen 518031China

For present solid oxide fuel cells(SOFCs),rapid performance degradation is observed in the initial aging process,and the dis-cussion of the degradation mechanism necessitates quantitative ***,focused ion beam-scanning electron microscopy was em-ployed to characterize and reconstruct the ceramic microstructures of SOFC *** lattice Boltzmann method(LBM)simulation of multiphysical and electrochemical processes in the reconstructed models was *** samples collected from industrial-size cells were characterized,including a reduced reference cell and a cell with an initial aging *** parameters of the reconstructed microstructures revealed a significant decrease in the active triple-phase boundary and Ni connectivity in the aged cell compared with the reference *** LBM simulation revealed that activity degradation is dominant compared with microstructural degradation during the initial aging process,and the electrochemical reactions spread to the support layer in the aged *** microstructural and activity de-gradations are attributed to Ni migration and coarsening.

关键词： solid oxide fuel cell anode degradation focused ion beam-scanning electron microscopy lattice Boltzmann method

Liberica coffee as an alternative cropping system for sustainable farming on Indonesian Peatlands

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International Journal of Agricultural and Biological Engineering 2024年第1期17卷 180-188页

作者： Bariot Hafif Yulius Ferry Budi Martono Rita Harni Kurnia Dewi Sasmita Busyra B.Saidi Maswar Maswar R.Bambang Heryanto Novizar Nazir Fahmuddin Agus Meynarti Sari Dewi Ibrahim National research and innovation Agency Research Center for Estate CropsIndonesia National research and innovation Agency Research Center for Food CropsIndonesia Faculty of Agricultural Technology Andalas UniversityIndonesia

Indonesian peatlands are a fragile ecosystem,and to protect it,growing Liberica coffee is a promising way for both the environment and the *** study aimed to evaluate the performance of the liberica coffee on peatland with different water tables and develop an improved cultivation system in this *** study area was in Tanjung Jabung Barat District,Jambi Province,*** plant age is greater than 15 years and the average plant density was about 1000 trees/*** study was conducted in two *** 1st stage was a survey to identify and characterize smallholder liberica coffee farming at three peatland zones,namely 0-100 m,200-300 m,and>400 m from the principal drainage canal,and the 2nd stage was a field experiment to test the effectiveness of amendments in improving liberica coffee growth and improving degraded *** treatments were arranged in a randomized complete block design with four replications,including manure(M),at the rate of 10 t/hm^(2);lime(L),3 t/hm^(2);peat surface elevation(P),and a farmer’s practice(Control)without manure and/or lime as a *** research revealed that liberica coffee can not tolerate high water table as it may stimulate disease incidence and cause low-quality ***,recycling of organic C of about 17.14 t/(hm^(2)·a)through cherry residue application and litter compensated part of the loss of organic C through CO_(2)emissions,coffee bean removal,and maintaining peat fertility for sustainable *** low yield of(0.70±0.12)t/(hm^(2)∙a)coffee bean could be increased to(0.87±0.24)and(0.94±0.14)t/(hm^(2)∙a)by adding 3 t/(hm^(2)∙3a)of lime or 10 t/(hm^(2)∙a)of manure,*** research revealed that water table management and amendments are two main factors in liberica coffee farming on *** is of great significance to study the cultivation technology of coffee in peatland.

关键词： degraded peat amendments water table cultivation system liberica coffee alternative cropping system sustainable farming Indonesian Peatlands

A hybrid spatial-temporal deep learning prediction model of industrial methanol-to-olefins process

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Frontiers of Chemical Science and Engineering 2024年第4期18卷 73-85页

作者： Jibin Zhou Xue Li Duiping Liu Feng Wang Tao Zhang Mao Ye Zhongmin Liu National Engineering research Center of Lower-Carbon Catalysis Technology Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China Yulin innovation institute for Clean Energy Clean Energy Innovation Institute of Chinese Academy of SciencesYulin 719053China Xuelang Industrial Intelligence Technology Co. Ltd.Wuxi 214000China

Methanol-to-olefins,as a promising non-oil pathway for the synthesis of light olefins,has been successfully *** accurate prediction of process variables can yield significant benefits for advanced process control and *** challenge of this task is underscored by the failure of traditional methods in capturing the complex characteristics of industrial processes,such as high nonlinearities,dynamics,and data distribution shift caused by diverse operating *** this paper,we propose a novel hybrid spatial-temporal deep learning prediction model to address these ***,a unique data normalization technique called reversible instance normalization is employed to solve the problem of different data ***,convolutional neural network integrated with the self-attention mechanism are utilized to extract the temporal ***,a multi-graph convolutional network is leveraged to model the spatial ***,the extracted temporal and spatial features are fused as input into a fully connected neural network to complete the ***,the outputs are denormalized to obtain the ultimate *** monitoring results of the dynamic trends of process variables in an actual industrial methanol-to-olefins process demonstrate that our model not only achieves superior prediction performance but also can reveal complex spatial-temporal relationships using the learned attention matrices and adjacency matrices,making the model more ***,this model is deployed onto an end-to-end Industrial Internet Platform,which achieves effective practical results.

关键词： methanol-to-olefins process variables prediction spatial-temporal self-attention mechanism graph convolutional network

Roles of Upper-Level Descending Inflow in Moat Development in Simulated Tropical Cyclones with Secondary Eyewall Formation

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Advances in Atmospheric Sciences 2024年第6期41卷 1100-1114页

作者： Nannan QIN Liguang WU Nanjing Joint institute for Atmospheric Sciences Nanjing 210041China Shanghai Typhoon institute China Meteorological AdministrationShanghai 200030China Department of Atmospheric and Oceanic Sciences and institute of Atmospheric Sciences Fudan UniversityShanghai 200438China innovation Center of Ocean and Atmosphere System Zhuhai Fudan Innovation Research InstituteZhuhai 518057China

This study investigated the effects of upper-level descending inflow(ULDI)associated with inner-eyewall convection on the formation of the moat in tropical cyclones(TCs)with secondary eyewall formation(SEF).In our numerical experiments,a clear moat with SEF occurred in TCs with a significant ULDI,while no SEF occurred in TCs without a significant *** eyewall convection developed more vigorously in the control run.A ULDI occurred outside the inner-eyewall convection,where it was symmetrically *** ULDI was initially triggered by the diabatic warming released by the inner eyewall and later enhanced by the cooling below the anvil *** ULDI penetrated the outer edge of the inner eyewall with relatively dry air and prevented excessive solid-phase hydrometeors from being advected further *** produced extensive sublimation cooling of falling hydrometeors between the eyewall and the outer *** sublimation cooling resulted in negative buoyancy and further induced strong subsidence between the eyewall and the outer *** a result,a clear moat was *** of the moat in the ongoing SEF prevented the outer rainband from moving farther inward,helping the outer rainband to symmetrize into an outer *** the sensitivity experiment,no significant ULDI formed since the eyewall convection was weaker,and the eyewall anvil developed relatively lower,meaning the formation of a moat and thus an outer eyewall was less *** study suggests that a better-represented simulation of inner-eyewall convective structures and distribution of the solid-phase hydrometeors is important to the prediction of SEF.

关键词： tropical cyclone secondary eyewall formation upper-level descending inflow eyewall convection

Predict the evolution of mechanical property of Al-Li alloys in a marine environment

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Defence Technology（防务技术） 2024年第1期31卷 557-566页

作者： Wei Li Lin Xiang Guang Wu Hongli Si Jinyan Chen Yiming Jin Yan Su Jianquan Tao Chunyang Huang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100036China Chongqing innovation Center Beijing Institute of TechnologyChongqing400044China First research institute of the Ministry of Public Security for PR China Beijing100036China Southwest Technology and Engineering research institute Chongqing400039China

The ocean is one of the essential fields of national defense in the future,and more and more attention is paid to the lightweight research of Marine equipment and *** study it is to develop a Machine learning(ML)-based prediction method to study the evolution of the mechanical properties of Al-Li alloys in the marine *** obtained the mechanical properties of Al-Li alloy samples under uniaxial tensile deformation at different exposure times through Marine exposure *** obtained the strain evolution by digital image correlation(DIC).The strain field images are voxelized using 2D-Convolutional Neural Networks(CNN)autoencoders as input data for Long Short-Term Memory(LSTM)neural ***,the output data of LSTM neural networks combined with corrosion features were input into the Back Propagation(BP)neural network to predict the mechanical properties of Al-Li *** main conclusions are as follows:*** variation law of mechanical properties of2297-T8 in the Marine atmosphere is *** the increase in outdoor exposure test time,the tensile elastic model of 2297-T8 changes slowly,within 10%,and the tensile yield stress changes significantly,with a maximum attenuation of 23.6%.*** prediction model can predict the strain evolution and mechanical response simultaneously with an error of less than 5%.*** study shows that a CNN/LSTM system based on machine learning can be built to capture the corrosion characteristics of Marine exposure *** results show that the relationship between corrosion characteristics and mechanical response can be predicted without considering the microstructure evolution of metal materials.

关键词： Marine environment Al-Li alloy Machine learning Corrosion

Oscillation of Dzyaloshinskii–Moriya interaction driven by weak electric fields

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Chinese Physics B 2024年第2期33卷 487-491页

作者：陈润泽曹安妮王馨苒柳洋杨洪新赵巍胜 Fert Beijing institute MIIT Key Laboratory of SpintronicsSchool of Integrated Circuit Science and EngineeringBeihang UniversityBeijing 100191China Hefei innovation research institute Beihang UniversityHefei 230013China Beihang-Goertek Joint Microelectronics institute Qingdao Research InstituteBeihang UniversityQingdao 266000China National Laboratory of Solid State Microstructures School of PhysicsCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China Beijing Microelectronics Technology institute Beijing 100076China

Dzyaloshinskii–Moriya interaction(DMI) is under extensive investigation considering its crucial status in chiral magnetic orders, such as Néel-type domain wall(DW) and skyrmions. It has been reported that the interfacial DMI originating from Rashba spin–orbit coupling(SOC) can be linearly tuned with strong external electric fields. In this work, we experimentally demonstrate that the strength of DMI exhibits rapid fluctuations, ranging from 10% to 30% of its original value, as a function of applied electric fields in Pt/Co/MgO heterostructures within the small field regime(research related to the voltage control of magnetic anisotropy for spin–orbit torque or the motion control of skyrmions might also have to consider the role of the external electric field on DMI as small voltages are generally used for the magnetoresistance detection.

关键词： Dzyaloshinskii-Moriya interaction weak electric field control effect Rashba spin-orbit coupling interfacial orbital hybridization