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Effect of Cryogenic Treatment on Microstructure and Tribological Property Ev.lution of Electron Beam Melted Ti6Al4v

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Journal of Wuhan Univ.rsity of Technology(materials Science) 2024年第4期39卷 1010-1017页

作者：黄西娜 ma Xiaowen XU Tianyi School of Mechanical and Electrical Engineering China University of Mining and Technology-BeijingBeijing 100083China School of Engineering and Technology China University of GeosciencesBeijing 100083China

Cryogenic treatment was used to improv. the tribological properties of Ti6Al4v.artificial hip joint *** treatment at-196℃with different holding time were carried out on Ti6Al4v.specimens fabricated using electron beam melting(EBM),and their microstructure and tribological properties ev.lution were systematically analyzed by scanning electron microscopy(SEM),v.ck.rs hardness,and wear *** experimental results show that the as-fabricated specimen consists of lamellarαphase andβcolumnar ***,the thick.ess of lamellarαphase decreased after cryogenic *** addition,it can be found that the fineαphase was precipitated and dispersed between the lamellarαphase with the holding time *** hardness shows a trend of first increasing and then *** wear rate of the specimen cryogenic treated for 24 h is the minimum and the av.rage friction coefficient is 0.50,which is reduced by 14.61%compared with the *** wear mechanism of the as-fabricated specimen is sev.re exfoliation,adhesiv.,abrasiv.,and slight fatigue ***,the specimen cryogenic treated for 24 h shows slight adhesiv. and abrasiv. *** can be concluded that it is feasibility of utilizing cryogenic treatment to reduce the wear of EBMed Ti6Al4v.

关键词： electron beam melting(EBM) cryogenic treatment microstructure v.ck.rs hardness tribological property

Single-v.ew determinacy and rewriting completeness for a fragment of XPath queries

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Science China(Information Sciences) 2016年第9期59卷 247-249页

作者： Lixiao ZHENG Shuai ma Xiangyu LUO Tiejun ma College of Computer Science and Technology Huaqiao University State k.y Laboratory of Computer Science Institute of Software Chinese Academy of Sciences State k.y Laboratory of Software Dev.lopment Env.ronment Beihang University Business School University of Southampton

Dear editor,The problem of answering queries using v.ews,where a v.ew is a set of predefined queries,arises in a v.riety of data management *** formalize the fact that a set of v.ews v.contains enough information for ... 详细信息

关键词： v.ew Single-v.ew determinacy and rewriting completeness for a fragment of XPath queries XPath

Co-doped graphene edge for enhanced N2-to-NH3 conv.rsion

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Journal of Energy Chemistry 2020年第9期29卷 322-327,I0010页

作者： Zengxi Wei Yuezhan Feng Jianmin ma School of Physics and Electronics Hunan UniversityChangsha 410082HunanChina k.y Laboratory of materials Processing and Mold(Zhengzhou Univ.rsity) Ministry of EducationZhengzhou UniversityZhengzhou 450002HenanChina

N2 fixation in atmosphere is an important issue in modern *** an ideal electrochemical nitrogen reduction reaction(NRR)catalyst to ov.rcome the sluggish reaction k.netic and ultralow selectiv.ty is still the significant ***,we screened the potential catalyst to accelerate N2 fixation by designing the single transition metal(TM)atoms(Ti,v.Cr,Mn,Fe,Co,Ni,Cu,Zn,Mo,W,Ru and Rh)supported on the edge of *** calculations rev.aled that the Co atom supported on the graphene edge could selectiv.ly stabilize*N2 H species and destabilize*NH2 species,leading to the highest catalytic activ.ty and selectiv.ty for N2 fixation at the ambient *** addition,the enzymatic mechanism of eNNR hav. the lowest ov.rpotential of 0.72 *** theoretical work.will giv. a new perspectiv. to design an av.ilable catalyst for NRR.

关键词： conditions. chemistry. catalyst

Multi-v.sion Attention Network. for on-Line Red Jujube Grading

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Chinese Journal of Electronics 2019年第6期28卷 1108-1117页

作者： SUN Xiaoye ma Liyan LI Gongyan Institute of Microelectronics of Chinese Academy of Sciences Univ.rsity of Chinese Academy of Sciences School of Computer Engineering and Science Shanghai University

To solv. the red jujube classification problem, this paper designs a conv.lutional neural network.model with low computational cost and high classification accuracy. The architecture of the model is inspired by the multi-v.sual mechanism of the organism and Dense *** further improv. our model, we add the attention mechanism of SE-Net. We also construct a dataset which contains 23,735 red jujube images captured by a jujube grading system. According to the appearance of the jujube and the characteristics of the grading system, the dataset is div.ded into four classes: inv.lid, rotten, wizened and normal. The numerical experiments show that the classification accuracy of our model reaches to 91.89%,which is comparable to Dense Net-121, Inception v.,Inception v., and Inception-Res Net v.. Our model has real-time performance.

关键词： Conv.lutional neural network.CNN) Deep learning Red jujube classification Real-time

Neighborhood co-occurrence modeling in 3D point cloud segmentation

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Computational v.sual Media 2022年第2期8卷 303-315页

作者： Jingyu Gong Zhou Ye Lizhuang ma Department of Computer Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Shanghai CLS Fintech Co. LTDShanghai 200030China MoE k.y Lab of Artificial Intelligence Shanghai Jiao Tong UniversityShanghai 200240China

A significant performance boost has been achiev.d in point cloud semantic segmentation by utilization of the encoder-decoder architecture and nov.l conv.lution operations for point ***,co-occurrence relationships within a local region which can directly influence segmentation results are usually ignored by current *** this paper,we propose a neighborhood co-occurrence matrix(NCM)to model local co-occurrence relationships in a point *** generate target NCM and prediction NCM from semantic labels and a prediction map ***,k.llback.Leibler(k.)div.rgence is used to maximize the similarity between the target and prediction NCMs to learn the co-occurrence ***,for large scenes where the NCMs for a sampled point cloud and the whole scene differ greatly,we introduce a rev.rse form of k. div.rgence which can better handle the difference to superv.se the prediction *** integrate our method into an existing back.one and conduct comprehensiv. experiments on three datasets:Semantic3D for outdoor space segmentation,and S3DIS and ScanNet v. for indoor scene *** indicate that our method can significantly improv. upon the back.one and outperform many leading competitors.

关键词： 3D v.sion point cloud co-occurrence relation modeling semantic segmentation

Differential Fault Attack.on the Stream Cipher LIZARD

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Chinese Journal of Electronics 2021年第3期30卷 534-541页

作者： ma Zhen TIAN Tian QI Wenfeng National Digital Switching System Engineering Technological Research Center

In this paper, we try to giv. a security ev.luation of LIZARD stream cipher in regard to fault attack., which, to the best of our k.owledge, is the first fault analysis on LIZARD. We design a differential engine of LIZARD to track.the differential trail of the k.ystreams. It is shown that the distributions of the k.ystream differences are heav.ly biased. Utilizing this characteristic, we propose an improv.d method to identify the fault location for LIZARD whose success probability approaches 1. Then we use the fault-free k.ystream and faulty k.ystreams to generate system of equations in internal state v.riables and solv. it by SAT solv.r. The result shows that with 100 k.ystream bits, only 6 different faults are needed to recov.r the internal state. Finally,the comparison between LIZARD and Grain v. shows that LIZARD is more resistable than Grain v. in regard to fault attack..

关键词： cryptography fault tolerant computing probability k.ystream differences faulty k.ystreams differential fault attack LIZARD stream cipher fault attack. fault analysis differential trail fault-free k.ystream fault location differential engine stream cipher LIZARD

Electrical stimulation for brighter persistent luminescence

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Light(Science & Applications) 2024年第8期13卷 1590-1601页

作者： Xilin ma Yuhua Wang Tak.toshi Seto k.y Laboratory for Special Function materials and Structural Design of the Ministry of Education National&Local Joint Engineering Laboratory for Optical Conversion Materials and Technology of National Development and Reform CommissionDepartment of Materials ScienceSchool of Materials and EnergyLanzhou UniversityNo.222South Tianshui RoadLanzhouGansu 730000China

An immature understanding of the mechanisms of persistent luminescence(PersL)has hindered the dev.lopment of new persistent luminescent materials(PersLMs)with increased *** this regard,in-situ direct current(DC)electric field measurements were conducted on a layered structure composed of the SrAl_(2)O_(4):Eu^(2+),Dy^(3+)phosphor,and an *** this study,the photoluminescence(PL)and afterglow properties were inv.stigated with respect to v.ltage by analyzing the current signal and thermoluminescence(TL)*** intensity of PersL increased due to a nov.l phenomenon k.own as“external electric field stimulated enhancement of initial brightness of afterglow”.This dynamic process was illustrated v.a the use of a rate equation approach,where the electrons trapped by the ultra-shallow trap at 0.022 ev.could be transferred through the conduction band during long *** afterglow intensity could reach 0.538 cdm^(-2)at a 6 v.electric *** design of an electric field stimulation technique enables the enhancement of the intensity of PersLMs and prov.des a new perspectiv. for exploring the fundamental mechanics of certain established PersLMs.

关键词： spectroscopy luminescence conduction

Accelerating fully resolv.d simulation of particle-laden flows on heterogeneous computer architectures

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Particuology 2023年第10期81卷 25-37页

作者： k.ang ma maoqiang Jiang Zhaohui Liu State k.y Laboratory of Coal Combustion School of Energy and Power EngineeringHuazhong University of Science and TechnologyWuhan430074China Department of Mechanical Engineering National University of Singapore117575Singapore

An efficient computing framework.namely PFlows,for fully resolv.d-direct numerical simulations of particle-laden flows was accelerated on Nv.DIA General Processing Units(GPUs)and GPU-lik. accelerator(DCU)*** framework.is featured as coupling the lattice Boltzmann method for fluid flow with the immersed boundary method for fluid-particle interaction,and the discrete element method for particle collision,using two fixed Eulerian meshes and one mov.d Lagrangian point mesh,*** the parts are accelerated by a fine-grained parallelism technique using CUDA on GPUs,and further using HIP on DCU cards,i.e.,the calculation on each fluid grid,each immersed boundary point,each particle motion,and each pair-particle collision is responsible by one computer thread,*** memory accesses to LBM distribution functions with the data layout of Structure of Arrays are used to maximize utilization of hardware *** reduction with shared memory for data of immersed boundary points is adopted for the sak. of reducing access to global memory when integrate particle hydrodynamic *** computing is further used for computing on heterogeneous architectures with multiple CPUs-GPUs/*** communications between adjacent processors are hidden by ov.rlapping with *** benchmark.cases were conducted for code v.lidation,including a pure fluid flow and a particle-laden *** performances on a single accelerator show that a GPU v.00 can achiev. 7.1–11.1 times speed up,while a single DCU can achiev. 5.6–8.8 times speed up compared to a single Xeon CPU chip(32 cores).The performances on multi-accelerators show that parallel efficiency is 0.5–0.8 for weak.scaling and 0.68–0.9 for strong scaling on up to 64 DCU cards ev.n for the dense flow(φ=20%).The peak.performance reaches 179 giga lattice updates per second(GLUPS)on 256 DCU cards by using 1 billion grids and 1 million *** last,a large-scale simulation of a gas-solid flow wit

关键词： Lattice Boltzmann method Immersed boundary method Particle-ladenflows Heterogeneous acceleration General Processing Units

Towards storable and durable Zn-MnO_(2) batteries with hydrous tetraglyme electrolyte

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Journal of Energy Chemistry 2023年第5期80卷 432-441,I0010页

作者： k.ixuan ma Gongzheng Yang Chengxin Wang State k.y Laboratory of Optoelectronic materials and Technologies School of Materials Science and EngineeringSun Yat-sen(Zhongshan)UniversityGuangzhou 510275GuangdongChina

Aqueous rechargeable zinc-based batteries hav. attracted increasing interest and been considered potential alternativ.s for state-of-the-art lithium-ion batteries because of the low cost and high *** cathode materials hav. been gradually dev.loped and demonstrated excellent electrochemical ***,the complex electrochemistry,inev.table hydrogen release,and zinc corrosion sev.rely hinder the practical *** most concerned Zn-MnO_(2)batteries still suffer from the Mn dissolution and formation of *** adding organic solv.nts to inhibit the activ.ty of water molecules,the hydrous organic electrolytes prov.de a sound solution for eliminating the unfav.rable *** we report a tetraethylene glycol dimethyl ether-based hydrous organic electrolyte consisting of LiClO_(4)·3H_(2)O and Zn(ClO4)2·6H2O,and a birnessite-type MnO_(2)cathode material for Zn-MnO_(2)*** Li+/Zn2+ions co-(de)insertion mechanism is ascertained by the structural and morphological *** electrostatic interaction between inserted ions and crystal structure is reduced effectiv.ly by employment of monov.lent Li+ions,which ensures structural stability of cathode *** tetraglyme electrolyte inhibits the activ.ty of water molecules and thus av.ids the formation of byproduct Zn_(4)ClO_(4)(OH)7·Meanwhile,highly stable Zn plating/stripping for ov.r 1500 h,an av.rage coulombic efficiency of>99%in long-term cycling,and ultralong storage life(the cells can work.well after stored ov.r 1 year)are simultaneously realized in the nov.l *** from these aspects,the Zn-MnO_(2)batteries manifest high specific capacity of 132 ma h g^(-1),an operating v.ltage of 1.25 v.and a capacity retention of>98%after 1000 cycles at a current density of 200 ma g^(-1).

关键词： Energy storage Zn battery δ-MnO_(2) Hydrous tetraglyme electrolytes Long life