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Mechanical behavior of SiC reinforced ZA63 Mg matrix composites: Experiments and 3D finite element modelling

Journal of Magnesium and Alloys 2025年第3期13卷 1294-1309页

作者： Chong Wang Zelong Du Enyu Guo Shuying Bai Zongning Chen Huijun Kang Guohao Du Yanling Xue Tongmin Wang Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian 116024China Ningbo Institute of Dalian University of Technology Ningbo 315000China Shanghai Synchrotron Radiation Facility Shanghai Advanced Research Institute CASShanghai201204China

In this work,the microstructure evolution and mechanical behavior of extruded SiC/ZA63 Mg matrix composites are investigated via combined experimental study and three-dimensionalﬁnite element modelling(3D FEM)based on the actual 3D microstructure achieved by synchrotron *** results show that the average grain size of composite increases from 0.57μm of 8μm-SiC/ZA63 to 8.73μm of 50μm-SiC/*** type of texture transforms from the typicalﬁber texture in 8μm-SiC/ZA63 to intense basal texture in 50μm-SiC/ZA63 composite and the intensity of texture increases sharply with increase of SiC particle *** dynamic recrystallization(DRX)mechanism is also changed with increasing SiC particle *** and simulation results verify that the strength and elongation both decrease with increase of SiC particle *** 8μm-SiC/ZA63 composite possesses the optimal mechanical property with yield strength(YS)of 383 MPa,ultimate tensile strength(UTS)of 424 MPa and elongation of 6.3%.The outstanding mechanical property is attributed to the ultraﬁne grain size,high-density precipitates and dislocation,good loading transfer effect and the interface bonding between SiC and matrix,as well as the weakened basal *** simulation results reveal that the micro-cracks tend to initiate at the interface between SiC and matrix,and then propagate along the interface between particle and Mg matrix or at the high strain and stress regions,and further connect with other *** main fracture mechanism in 8μm-SiC/ZA63 composite is ductile damage of matrix and interfacial *** the increase of particle size,interface strength and particle strength decrease,and interface debonding and particle rupture become the main fracture mechanism in the 30μm-and 50μm-SiC/ZA63 composites.

关键词： Mg matrix composite Synchrotron tomography 3D finite element model Microstructure evolution Mechanical property

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A Review on the Security of the Ethereum-Based DeFi Ecosystem

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Computer Modeling in engineering & Sciences 2024年第4期139卷 69-101页

作者： Yue Xue Dunqiu Fan Shen Su Jialu Fu Ning Hu Wenmao Liu Zhihong Tian Cyberspace Institute of Advanced Technology Guangzhou UniversityGuanzhou510000China Innovation Center NSFOCUS Inc.Beijing100089China Engineering Research Center of Integration and Application of Digital Learning Technology Ministry of EducationBeijing100816China

Decentralized finance(DeFi)is a general term for a series of financial products and *** is based on blockchain technology and has attracted people’s attention because of its open,transparent,and intermediary *** them,the DeFi ecosystem based on Ethereum-based blockchains attracts the most ***,the current decentralized financial system built on the Ethereum architecture has been exposed to many smart contract vulnerabilities during the last few ***,we believe it is time to improve the understanding of the prevailing Ethereum-based DeFi ecosystem security *** that end,we investigate the Ethereum-based DeFi security issues:1)inherited from the real-world financial system,which can be solved by macro-control;2)induced by the problems of blockchain architecture,which require a better blockchain platform;3)caused by DeFi invented applications,which should be focused on during the project *** on that,we further discuss the current solutions and potential directions ofDeFi *** to our research,we could provide a comprehensive vision to the research community for the improvement of Ethereum-basedDeFi ecosystem security.

关键词： Blockchain smart contract decentralized finance DeFi security

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Body-force modeling considering induced upstream effects for a transonic compressor with total temperature distortion

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Chinese Journal of Aeronautics 2024年第6期37卷 7-19页

作者： Jiahui QIU Chen YANG Wenqiang ZHANG Min ZHANG Juan DU Digital Twin Research Center Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China School of Engineering and Science University of Chinese Academy of SciencesBeijing 100190China National Key Laboratory of Science and Technology on Advanced Light-duty Gas-turbine Chinese Academy of SciencesBeijing 100190China School of Mechatronical Engineering Beijing Institute of TechnologyBeijing 100081China

To numerically study the impact of total temperature distortion on a transonic compressor with reduced computational costs,a Body-Force Model(BFM)is ***,the interactions between the distorted flow and the compressor are analyzed using full-annulus Unsteady Reynolds-Averaged Navier-Stokes(URANS)results and the orbit *** is found that the induced swirl distortion and the mass flux nonuniformity are intensified in the compressor upstream flow field.A correction factor is thus added to the BFM to account for the effect of the induced swirl,which is crucial for the accurate representation of distortion transfer in the ***,steady simulations with large-amplitude 180circumferential total temperature distortion are performed using the developed *** is shown that the distorted compressor map simulated with the BFM matches well with URANS *** circumferential phase shift of total temperature and the generation of the additional total pressure distortion across the rotor are in line with the time-averaged URANS flow *** compressor upstream effects on the distorted inflow can also be exactly *** above-mentioned results demonstrate the BFM developed in this paper can effectively capture the distorted flow features inside the compressor,and significantly reduce the computational costs by five orders of magnitude compared with URANS.

关键词： Upstream effect Orbit method Induced swirl distortion Body force model Correction factor Time-averaged URANS

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From food waste to high-capacity hard carbon for rechargeable sodium-ion batteries

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Carbon Resources Conversion 2024年第3期7卷 66-73页

作者： Madina Kalibek Lunara Rakhymbay Zhanar Zhakiyeva Zhumabay Bakenov Seung-Taek Myung Aishuak Konarov Department of Chemical and Materials Engineering School of Engineering and Digital SciencesNazarbayev University53 Kabanbay Batyr Ave.AstanaKazakhstan Hybrid Materials Research Center Department of Nanotechnology and Advanced Materials EngineeringSejong Battery InstituteSejong UniversitySeoul 05006South Korea

In this study,we introduce a straightforward and effective approach to produce P-doped hard carbon using coffee grounds as the precursor,with H_(3)PO_(4)serving as the doping *** varying the concentrations of H_(3)PO_(4)(1 M,2 M,and 3 M),we aimed to determine the optimal doping level for maximizing the incorporation of phosphorus ions into the carbon *** investigation revealed that using 2 M of H_(3)PO_(4)as the dopant material for hard carbon led to promising electrochemical performance when employed as an anode material for sodium-ion *** P-doped hard carbon,carbonized at 1300℃,exhibited an impressive reversible capacity of 341 mAh g^(-1) at a current density of 20 mA g^(-1),with an initial Coulombic efficiency(ICE)of 83%.This outstanding electrochemical performance of P-doped hard carbon can be attributed to its unique properties,including a porous agglomerated structure,a significant interlayer spacing,and the formation of C-P bonds.

关键词： Coffee waste Hard carbon Phosphorus doping Sodium-ion batteries

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Ab Initio Investigations for the Role of Compositional Complexities in Affecting Hydrogen Trapping and Hydrogen Embrittlement:A Review

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Acta Metallurgica Sinica(English Letters) 2023年第7期36卷 1159-1172页

作者： Boning Zhang Yong Mao Zhenbao Liu Jianxiong Liang Jun Zhang Maoqiu Wang Jie Su Kun Shen Advanced Computing Center School of Materials and EnergyYunnan UniversityKunming650091China Institute for Special Steel Research Central Iron and Steel Research InstituteBeijing100081China Key Laboratory of Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua UniversityBeijing100084China School of Science China University of GeosciencesBeijing100083China

ydrogen embrittlement(HE)seriously restricts the service safety of structural metallic materials applicate in aerospace,ocean,and *** studies aiming at increasing the HE-resistance have been focusing on trapping diffusible H atoms by inherent microstructural features in ***-induced compositional complexities,including different types of solute atoms,lattice chemical heterogeneities,and carbide precipitates,have attracted research efforts regarding the H trapping capabilities and potential to reduce the susceptibility to *** this paper,we review recent progress in exploiting compositional complexities to regulate the hydrogen trapping characteristics and mechanical properties in H-containing *** focus is placed on results and insights from ab initio calculations based on density functional theory(DFT).Quantitative predictions of trapping parameters and atomic scale details that are hardly to be gained through traditional experimental characterizations are ***,we overview the electronic/atomistic mechanisms of H trapping energetics in metallic ***,we propose some key challenges and prospects in simulation of defect interactions,interpretation of experimental characterizations,and developing microstructure-based H diffusion prediction *** the applications of first principle calculations,we illustrate how the DFT data can complement experimental characterizations to guide composition and microstructure design for better HE-resistant materials.

关键词： Ab initio calculations Hydrogen trapping Hydrogen embrittlement Precipitation Composition design

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Data quantity governance for machine learning in materials science

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National Science Review 2023年第7期10卷 234-250页

作者： Yue Liu Zhengwei Yang Xinxin Zou Shuchang Ma Dahui Liu Maxim Avdeev Siqi Shi School of Computer Engineering and Science Shanghai University Shanghai Engineering Research Center of Intelligent Computing System Australian Nuclear Science and Technology Organisation School of Chemistry The University of Sydney State Key Laboratory of Advanced Special Steel School of Materials Science and Engineering Shanghai University Materials Genome Institute Shanghai University

Data-driven machine learning(ML) is widely employed in the analysis of materials structure-activity relationships,performance optimization and materials design due to its superior ability to reveal latent data patterns and make accurate ***,because of the laborious process of materials data acquisition,ML models encounter the issue of the mismatch between a high dimension of feature space and a small sample size(for traditional ML models) or the mismatch between model parameters and sample size(for deep-learning models),usually resulting in terrible ***,we review the efforts for tackling this issue via feature reduction,sample augmentation and specific ML approaches,and show that the balance between the number of samples and features or model parameters should attract great attention during data quantity *** this,we propose a synergistic data quantity governance flow with the incorporation of materials domain *** summarizing the approaches to incorporating materials domain knowledge into the process of ML,we provide examples of incorporating domain knowledge into governance schemes to demonstrate the advantages of the approach and *** work paves the way for obtaining the required high-quality data to accelerate materials design and discovery based on ML.

关键词： machine learning data governance data quantity materials science

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Tailoring the Microstructure and Mechanical Property of Mg-Zn Matrix Composite via the Addition of Al Element

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 438-452页

作者： Chong Wang Fuyuan Liu Xuejian Wang Enyu Guo Zelong Du Kunkun Deng Zongning Chen Huijun Kang Guohao Du Tongmin Wang Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian 116024China School of Mechanical Engineering Guizhou UniversityGuiyang 550025China Ningbo Institute of Dalian University of Technology Ningbo 315000China Shanxi Key Laboratory of Advanced Magnesium-Based Materials College of Materials Science and EngineeringTaiyuan University of TechnologyTaiyuan 030024China Shanghai Synchrotron Radiation Facility Shanghai Advanced Research Institute CASShanghai 201204China

The semi-solid stir casting method is adopted to prepare 10 wt%SiC_(p)/Mg-6Zn-0.5Ca-xAl(x=0,1,3 and 5 wt%)composites,and the microstructure evolution and mechanical property of composites with various Al content are *** results show that the addition of 3 wt%Al improves the distribution of SiC_(p),whereas the SiC_(p) cluster occurs again with Al content greater than 3%.An abnormal phenomenon of twinning is observed in the cast composites in this *** SiC_(p)/Mg-6Zn-0.5Ca composite possesses the highest twin content of~23%,for which tension twins(TTW)and compression twins(CTW)account for~19%and~3%,*** CTW is only observed in ZXA600 *** addition of Al has an inhibiting effect for the generation and growth of *** content of twin decreases firstly and then increases with increase of Al *** lowest twin content is obtained as Al increases to 3 wt%.It is found the existence of twin is detrimental to the mechanical property of ***-cast SiC_(p)/Mg-6Zn-0.5Ca-3Al composite with the lowest twin content exhibits the optimal mechanical property of yield strength,ultimate tensile strength and elongation for 100 MPa,188 MPa and 4.4%,*** outstanding mechanical property is attributed to the uniform distribution of SiC_(p),the low twin content and the well-distributed fine second phases.

关键词： Mg matrix composite Synchrotron tomography Twinning Liquid melt processing Mechanical property

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Ferroelectric-controlled graphene plasmonic surfaces for all-optical neuromorphic vision

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Science China(Technological Sciences) 2024年第3期67卷 765-773页

作者： CHEN JianBo LIU Yu LI ShangDong LIN Lin LI YaDong HUANG Wen GUO JunXiong School of Electronic Information and Electrical Engineering Institute for Advanced StudyChengdu UniversityChengdu 610106China School of Integrated Circuits Tsinghua UniversityBeijing 100084China School of Integrated Circuits(National Exemplary Schoolof Microelectronics) Universityof Electronic Science and Technologyof China Chengdu 610054China Jincheng Research Institute of Opto-mechatronics Industry Jincheng 048000China Shanxi Key Laboratory of Advanced Semiconductor Optoelectronic Devices and Integrated Systems Jincheng 048000China Engineering Research Center of Digital Imaging and Display Ministry of EducationSoochow UniversitySuzhou 215006China

Artificial visual systems can recognize desired objects and information from complex environments, and are therefore highly desired for pattern recognition, object detection, and imaging applications. However, state-of-the-art artificial visual systems with high recognition performances that typically consist of electronic devices face the challenges of requiring huge storage space and high power consumption owing to redundant data. Here, we report a terahertz(THz) frequency-selective surface using a graphene split-ring resonator driven by ferroelectric polarization for efficient visual system applications. The downward polarization of the ferroelectric material offers an ultrahigh electrostatic field for doping p-type graphene with an anticipated Fermi level. By optimizing the geometric parameters of the devices and modulating the carrier behaviors of graphene, our plasmonic devices exhibit a tunable spectral response in a range of 1.7–6.0 THz with continuous transmission values. The alloptical neural network using graphene plasmonic surfaces designed in this study exhibited excellent performance in visual preprocessing and convolutional filtering and achieved an ultrahigh recognition accuracy of up to 99.3% in training the Modified National institute of Standards and Technology(MNIST) handwritten digit dataset. These features demonstrate the great potential of graphene plasmonic devices for future smart artificial vision systems.

关键词： graphene plasmon ferroelectric frequency selective surface artificial vision system

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Sentiment Analysis on Climate Change for Sustainable Investment 24

Sentiment Analysis on Climate Change for Sustainable Investm...

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24th IEEE International Conference on Data Mining Workshops, ICDMW 2024

作者： Ong, Keane Mao, Rui Varshney, Deeksha Satapathy, Ranjan Cambria, Erik Mengaldo, Gianmarco National University of Singapore Asian Institute of Digital Finance Singapore Nanyang Technological University College of Computing and Data Science Singapore National University of Singapore College of Design & Engineering Singapore Agency for Science Technology and Research Institute of High Performance Computing Singapore

ISBN: (纸本)9798331530631

This research involves examining whether sentiment on climate change can be accounted as a systematic risk factor within sustainable finance. Tweets related to climate change from 2014-2022 are collected via the Twitter API. RoBERTa is then deployed to label the collected tweets according to sentiment polarity. Thereafter, DistilBERT is utilised to classify tweets according to their different climate change topics Aggregated, Impact, Politics &icy, Mitigation, Rootcause. Using these sentiment and topic labels, monthly sentiment scores are aggregated from the frequency of sentiment polarity (number of positive, and negative tweets), and segmented according to the topics that the tweets are classified under. On the other hand, we collect the monthly returns of various green ETFs, alongside ETFs that contain stocks from other sectors (technology, oil and gas), as well as 2 baskets of stocks (sustainable and heavy-polluting). We run Fama-French regressions by conducting time series regression of monthly returns on the traditional 3 factors, with specific addition of sentiment scores. © 2024 IEEE.

关键词： Tweets

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Mitigating Barren Plateaus of Variational Quantum Eigensolvers

IEEE Transactions on Quantum Engineering

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IEEE Transactions on Quantum engineering 2024年第1期5卷 1-19页

作者： Liu, Xia Liu, Geng Zhang, Hao-Kai Huang, Jiaxin Wang, Xin Thrust of Artificial Intelligence Information Hub Guangzhou510530 China Institute of Information Engineering Chinese Academy of Sciences Key Laboratory of Cyberspace Security Defense Beijing100085 China Baidu Research Institute for Quantum Computing Beijing100193 China Tsinghua University Institute for Advanced Study Beijing100084 China

Variational quantum algorithms (VQAs) are expected to establish valuable applications on near-term quantum computers. However, recent works have pointed out that the performance of VQAs greatly relies on the expressibility of the ansatzes and is seriously limited by optimization issues, such as barren plateaus (i.e., vanishing gradients). This article proposes the state-efficient ansatz (SEA) for accurate ground state preparation with improved trainability. We show that the SEA can generate an arbitrary pure state with much fewer parameters than a universal ansatz, making it efficient for tasks like ground state estimation. Then, we prove that barren plateaus can be efficiently mitigated by the SEA and the trainability can be further improved most quadratically by flexibly adjusting the entangling capability of the SEA. Finally, we investigate a plethora of examples in ground state estimation where we obtain significant improvements in the magnitude of the cost gradient and the convergence speed. © 2020 IEEE.

关键词： Timing circuits

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