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Numerical simulation of melt flow and temperature field during DC casting 2024 aluminium alloy under different casting conditions

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China Foundry 2024年第4期21卷 387-396页

作者： Jin-chuan Wang Yu-bo Zuo Qing-feng Zhu Jing Li Rui Wang xu-dong liu Key Laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110819China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China Engineering Research Center of Advanced Materials Preparing Technology Ministry of EducationShenyang 110819China CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Casting speed,casting temperature and secondary cooling water flow rate are the main process parameters affecting the DC casting *** parameters significantly influence the flow and temperature fields during casting,which are crucial for the quality of the ingot and can determine the success or failure of the casting *** simulation,with the advantages of low cost,rapid execution,and visualized results,is an important method to study and optimize the DC casting *** the present work,a simulation model of DC casting 2024 aluminum alloy was established,and the reliability of the model was ***,the influence of casting parameters on flow field and temperature field was studied in detail by numerical simulation *** show that with the increase of casting speed,the melt flow becomes faster,the depths of slurry zone and mushy zone increase,and the variation of slurry zone depth is greater than that of mushy *** an increase in casting temperature,the melt flow rate increases,the depth of the slurry zone becomes shallower,and the depth of the mushy zone experiences only minor *** simulation results further indicate that the increase of the flow rate of the secondary cooling water slightly reduces the depths of both slurry and mushy zone.

关键词： aluminium DC casting flow field temperature field numerical simulation

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Analysis of pseudo-random number generators in QMC-SSE method

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Chinese Physics B 2024年第3期33卷 75-79页

作者：刘东旭徐维张学锋 Department of Physics Chongqing UniversityChongqing 401331China

In the quantum Monte Carlo(QMC)method,the pseudo-random number generator(PRNG)plays a crucial role in determining the computation ***,the hidden structure of the PRNG may lead to serious issues such as the breakdown of the Markov ***,we systematically analyze the performance of different PRNGs on the widely used QMC method known as the stochastic series expansion(SSE)*** quantitatively compare them,we introduce a quantity called QMC efficiency that can effectively reflect the efficiency of the *** testing several representative observables of the Heisenberg model in one and two dimensions,we recommend the linear congruential generator as the best choice of *** work not only helps improve the performance of the SSE method but also sheds light on the other Markov-chain-based numerical algorithms.

关键词： stochastic series expansion quantum Monte Carlo pseudo-random number generator

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Twisted Integration of Complex Oxide Magnetoelectric Heterostructures via Water‑Etching and Transfer Process

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Nano-Micro Letters 2024年第1期16卷 360-369页

作者： Guannan Yang Guohua dong Butong Zhang xu xu Yanan Zhao Zhongqiang Hu Ming liu State Key Laboratory for Manufacturing Systems Engineering Electronic Materials Research LaboratoryKey Laboratory of the Ministry of EducationEngineering Research Center of Spin Quantum Sensor ChipsUniversities of Shaanxi ProvinceSchool of Electronic Science and EngineeringXi’an Jiaotong UniversityXi’an 710049People’s Republic of China

Manipulating strain mode and degree that can be applied to epitaxial complex oxide thin films have been a cornerstone of strain *** recent years,lift-off and transfer technology of the epitaxial oxide thin films have been developed that enabled the integration of heterostructures without the limitation of material types and crystal ***,twisted integration would provide a more interesting strategy in artificial magnetoelectric heterostructures.A specific twist angle between the ferroelectric and ferromagnetic oxide layers corresponds to the distinct strain regulation modes in the magnetoelectric coupling process,which could provide some insight in to the physical *** this work,the La_(0.67)Sr_(0.33)MnO_(3)(001)/0.7Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.3PbTiO_(3)(011)(LSMO/PMN-PT)heterostructures with *** *** angles were assembled via water-etching and transfer *** transferred LSMO films exhibit a fourfold magnetic anisotropy with easy axis along LSMO.A coexistence of uniaxial and fourfold magnetic anisotropy with LSMO[110]easy axis is observed for the 45°Sample by applying a 7.2 kV cm^(−1)electrical field,significantly different from a uniaxial anisotropy with LSMO[100]easy axis for the 0°*** fitting of the ferromagnetic resonance field reveals that the strain coupling generated by the 45°twist angle causes different lattice distortion of LSMO,thereby enhancing both the fourfold and uniaxial *** work confirms the twisting degrees of freedom for magnetoelectric coupling and opens opportunities for fabricating artificial magnetoelectric heterostructures.

关键词： Magnetoelectric heterostructures Twist angle Epitaxial lift-off Magnetic anisotropy Ferromagnetic resonance

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Atomically precise Ru-O-Ru clusters for enhanced water dissociation in alkaline hydrogen evolution

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Nano Research 2024年第8期17卷 6993-7000页

作者： dong liu Li xu Sicheng Li Airong xu Yuanhua Sun Tong liu Mengyuan liu Huijuan Wang Xiaokang liu Tao Yao Tao Ding Hefei National Research Center for Physical Sciences at the Microscale School of Nuclear Science and TechnologyKey Laboratory of Precision and Intelligent ChemistryNational Synchrotron Radiation LaboratoryUniversity of Science and Technology of ChinaHefei 230029China Experimental Center of Engineering and Materials Science University of Science and Technology of ChinaHefei 230026China

Atomic clusters typically exhibit distinctive electronic structures and physicochemical ***,as the size decreases,their ability to adsorb and dissociate water also diminishes,thereby affecting chemical reactions involving water *** the adsorption and dissociation capabilities of atomic clusters towards water molecules and elucidating the mechanisms underlying their performance enhancement have become important research ***,employing the carrier-anchored strategy,Ru-O-Ru atomic clusters were prepared and displayed excellent activity and durability in the hydrogen evolution ***,the Ru-O-Ru atomic clusters exhibited only 86 mV overpotential at 100 mA·cm−^(2)and superior membrane-electrode-assembly activity than commercial Ru/C *** radiation-based Fourier transform infrared spectroscopic measurements revealed that the modification of oxygen in Ru-O-Ru units promoted the reorientation of water molecules from a H-up orientation to H-down,therefore,enhanced the formation of strong hydrogen-bond network of interfacial water on the surface of Ru-O-Ru clusters,leading to enhanced adsorption and dissociation of water and accelerated Volmer *** findings provide a potential strategy and deep insights for the development of atomic clusters in electrocatalysts.

关键词： hydrogen evolution in-situ Fourier transform infrared(FTIR) Ru catalysts electrocatalysis atomic clusters

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An improved analysis method for assessing the nuclear-heating impact on the stability of toroidal field magnets in fusion reactors

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Nuclear Science and Techniques 2024年第6期35卷 163-176页

作者： Yu-dong Lu Jin-Xing Zheng xu-Feng liu Huan Wu Jian Ge Kun xu Ming Li Hai-Yang liu Lei Zhu Fei liu Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China

The superconducting magnet system of a fusion reactor plays a vital role in plasma confinement,a process that can be dis-rupted by various operational factors.A critical parameter for evaluating the temperature margin of superconducting magnets during normal operation is the nuclear heating caused by D-T *** study investigates the impact of nuclear heat-ing on a superconducting magnet system by employing an improved analysis method that combines neutronics and thermal *** the magnet system,toroidal field(TF)magnets are positioned closest to the plasma and bear the highest nuclear-heat load,making them prime candidates for evaluating the influence of nuclear heating on *** enhance the modeling accuracy and facilitate design modifications,a parametric TF model that incorporates heterogeneity is established to expedite the optimization design process and enhance the accuracy of the computations.A comparative analysis with a homogeneous TF model reveals that the heterogeneous model improves accuracy by over 12%.Considering factors such as heat load,magnetic-field strength,and cooling conditions,the cooling circuit facing the most severe conditions is selected to calculate the temperature of the *** selection streamlines the workload associated with thermal-hydraulic *** approach enables a more efficient and precise evaluation of the temperature margin of TF ***,it offers insights that can guide the optimization of both the structure and cooling strategy of superconducting magnet systems.

关键词： Superconducting magnet Nuclear heating Neutronics Thermal hydraulics

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Intelligent representation method of image flatness for cold rolled strip

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Journal of Iron and Steel Research(International) 2024年第5期31卷 1177-1195页

作者： Yang-huan xu dong-cheng Wang Hong-min liu Bo-wei Duan National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan UniversityQinhuangdao066004HebeiChina National Key Laboratory of Metal Forming Technology and Heavy Equipment China National Heavy Machinery Research Institute Co.Ltd.Xi’an710018ShaanxiChina State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao066004HebeiChina

Real flatness images are the bases for flatness detection based on machine vision of cold rolled *** characteristics of a real flatness image are analyzed,and a lightweight strip location detection(SLD)model with deep semantic segmentation networks is *** interference areas in the real flatness image can be eliminated by the SLD model,and valid information can be *** this basis,the concept of image flatness is proposed for the first *** image flatness representation(IFAR)model is established on the basis of an autoencoder with a new *** optimal structure of the bottleneck layer is 16×16×4,and the IFAR model exhibits a good representation ***,interpretability analysis of the representation factors is carried out,and the difference and physical meaning of the representation factors for image flatness with different categories are *** flatness with new defect morphologies(bilateral quarter waves and large middle waves)that are not present in the original dataset are generated by modifying the representation factors of the no wave ***,the SLD and IFAR models are used to detect and represent all the real flatness images on the test *** average processing time for a single image is 11.42 ms,which is suitable for industrial *** research results provide effective methods and ideas for intelligent flatness detection technology based on machine vision.

关键词： Cold rolled strip Image flatness Location detection Representation learning Bottleneck layer

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Classification and rating of disintegrated dolomite strata for slope stability analysis

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2552-2562页

作者： Wenlian liu Xinyue Gong Jiaxing dong Hanhua xu Peixuan Dai Shengwei Zhang Kunming Prospecting Design Institute of China Nonferrous Metals Industry Co. Ltd.Kunming650051China Key Laboratory of Geotechnical Engineering and Geological Disasters of Yunnan Province Kunming650051China Faculty of Electric Power Engineering Kunming University of Science and TechnologyKunming650500China

Although disintegrated dolomite,widely distributed across the globe,has conventionally been a focus of research in underground engineering,the issue of slope stability issues in disintegrated dolomite strata is gaining increasing *** is primarily due to their unique properties,including low strength and loose *** methods for evaluating slope stability,such as basic quality(BQ)and slope stability probability classification(SSPC),do not adequately account for the poor integrity and structural fragmentation characteristic of disintegrated *** address this challenge,an analysis of the applicability of the limit equilibrium method(LEM),BQ,and SSPC methods was conducted on eight disintegrated dolomite slopes located in Baoshan,Southwest ***,conflicting results were ***,this paper introduces a novel method,SMRDDS,to provide rapid and accurate assessment of disintegrated dolomite slope *** method incorporates parameters such as disintegrated grade,joint state,groundwater conditions,and excavation *** findings reveal that six slopes exhibit stability,while two are considered partially ***,the proposed method demonstrates a closer match with the actual conditions and is more time-efficient compared with the BQ and SSPC ***,due to the limited research on disintegrated dolomite slopes,the results of the SMRDDS method tend to be conservative as a safety *** conclusion,the SMRDDS method can quickly evaluate the current situation of disintegrated dolomite slopes in the *** contributes significantly to disaster risk reduction for disintegrated dolomite slopes.

关键词： Disintegrated dolomite slope Basic quality(BQ) Slope stability probability classification (SSPC) Rock mass quality classification Limit equilibrium method(LEM)

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Enzymatic self-assembly/disassembly turns “ON”/“OFF” the mimetic hydrolytic activity of histidine nanofibers

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Science China Chemistry 2024年第2期67卷 517-522页

作者： Xianbao Sun Manli Wang Xiaoyang liu Wenjun Zhan Guangqiong xu Qiaochu Jiang Hai-dong xu Fuqiang Wang Gaolin Liang State Key Laboratory of Digital Medical Engineering School of Biological Science and Medical EngineeringSoutheast UniversityNanjing210096China Analysis Center Nanjing Medical UniversityNanjing210029China

Mimetic enzymes are devised as alternates or supplements of natural enzymes in broad fields but regulating their activities in a switchable manner remains ***,we proposed an enzymatic self-assembly/disassembly strategy to address this issue.A peptide molecule Nap FFEYIH(YH) was rationally designed which,after self-assembling into nanofibers,lined up the histidine moieties to form active hydrolysis centers for mimicking hydrolase *** dephosphorylation of Nap FFEYp IH(Yp H) by alkaline phosphatase to yield YH also turned “ON” the hydrolase *** turn,phosphorylation of YH by phosphokinase epidermal growth factor receptor to yield Yp H disassembled the nanofibers and thus turned the activity “OFF”.As such,the “ON”/“OFF” of the mimetic hydrolase activities could be regulated under physiological conditions through ALP/EGFR-mediated self-assembly/disassembly of histidine *** work provides a feasible strategy for the on-demand fabrication of artificial enzymes with controllable and superior activities.

关键词： disassembly hydrolytic activity mimetic enzyme phosphorylation self-assembly

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Divergent defluorocarboxylation of α-CF_(3) alkenes with formate via photocatalyzed selective mono-or triple C-F bond cleavage

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Science China Chemistry 2024年第1期67卷 368-373页

作者： Xing-Yu Wang Pei xu Wen-Wen liu Hao-Qiang Jiang Song-Lei Zhu dong Guo xu Zhu Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy School of PharmacyXuzhou Medical UniversityXuzhou 22100China

Unprecedented divergent synthesis of gem-difluorovinylacetic acid and glutaric acid derivatives fromα-CF_(3)alkenes with formate as the carbonyl source was *** reaction can undergo selective mono-or triple C-F bond cleavage by simply switching the photocatalyst and hydrogen atom transfer(HAT)catalyst under visible-light-induced conditions at room *** acts as both the C1 source and the reductant through the generation of CO_(2)^(·-)species,which underwent Giese radical addition to electron-deficient alkenes to trigger the consecutive C-F bond cleavage and carboxylation process.

关键词： C-F bond activation defluorocarboxylation carbon dioxide radical anion visible light

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Room-temperature hydrogen spillover achieving stoichiometric hydrogenation of NO_(3)^(-) and NO_(2)^(-) into N_(2) over CuPd nanowire network

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Rare Metals 2022年第3期41卷 851-858页

作者： Ruo-Yan Miao xue-Xiang Li Qian Lei Hu liu Zhen-Hui Ma xu-dong liu Zhou-Yang Yin Zuo-Bin Tang Liang Zhang Yu-Hong Tian School of Chemistry and Chemical Engineering Xi’an University of Architecture and TechnologyXi’an 710055China School of Chemistry and Chemical Engineering Northwestern Polytechnical UniversityXi’an 710072China Department of Physics Beijing Technology and Business UniversityBeijing 100048China Department of Chemistry University of VirginiaCharlottesvilleVA 22904USA

The development of an efficient hydrogen spillover (HS)catalyst achieves the stoichiometric chemoselective hydrogenation of NO_(3)^(-)and NO_(2)^(-)into N_(2) at room temperature,which is extremely ***,we report a Cu_(x)Pd_(1-x) nanowire network (NWN)(x=7,5,or 3) with tunable hydrogen spillover rate of formic acid (FA) with polyvinylpyrrolidine imine (PVPI) modifying its surface.

关键词： network hydrogen (3)

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