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Loading-unloading judgement for advanced plastic UH model

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Acta Mechanica Sinica 2020年第4期36卷 827-839页

作者： x.Feng y.P.yao R.N.Li Z.Wan x.dai College of Airport Civil Aviation University of ChinaTianjin 300300China School of Transportation Science and Engineering Beihang UniversityBeijing 100191China School of Automobile and Transportation Tianjin University of Technology and EducationTianjin 300222China Research Institute of Base and Foundation China Academy of Building ResearchBeijing 100013China

The unified hardening(UH)model proposed by yao et al.(Geotechnique 2009)is the constitutive model which can consider the influence of the complex stress path and stress history on the deformation and strength of clays ***,the loading-unloading criterion of material model is defined as the change law of the intersection of current yield surface and the p axis,which makes the loading-unloading in the process of hardening and softening can be unified considered in UH ***,the Newton-Raphson method is adopted to attain the nonlinear problems solution in the finite element method of UH model,and the semi-implicit return mapping method is adopted to update *** application of the UH model in the finite element is *** then,the analyses of triaxial test are performed using the unit prediction and finite element *** results of the unit prediction method are compared with the experimental results to illustrate the rationality of the UH *** the results with the unit prediction method and the finite element method,the correctness of the finite element program of the UH model is ***,Ae three-dimensional firdte element andysis of embankment on soft soil is performed by the *** comparison between the results calculated by the UH model and the modified Cam-clay(MCC)model and the experimental data shows that the UH model is rational in analyzing the actual embankment engineering on soft soil.

关键词： Over-consolidated clay Unified hardening model Loading-unloading judgement Finite element method Stress-strain

Discovery of new MAx-phase-like layered ternary carbide V_(8)P_(6)C:Crystal structure,thermal expansion,and elastic properties

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Journal of Materials Science & Technology 2024年第7期174卷 55-62页

作者： H.x.Chen L.Sheng Z.L.Zhang x.C.Wen D.L.yang x.y.ye P.Q.dai School of Materials Science and Engineering Fujian University of TechnologyFuzhou 350118China Beijing Synchrotron Radiation Facility Institute of High Energy PhysicsChinese Academy of ScienceBeijing 100049China Fujian Provincial Key Laboratory of Advanced Materials Processing and Application Fuzhou 350118China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China

Due to the laminated structure,MAx phases and MAx-phase-like compounds possess outstanding dam-age tolerance capability with good thermal/electrical conductivity and other charming functional prop-erties,showing a bright future for structural-functional ***,a new MAx-phase-like ternary car-bide V_(8)P_(6)C with layered characteristics was *** to the alternate stacking of hexagonal-arranged M/A/x atom layers in MAx phases,V_(8)P_(6)C has a layered structure formed by a repeated stacking of the slabs consisting of V_(6)C-octahedrons and VP 6-distorted-octahedrons in three-atomic layers *** thermal expansion anisotropy was revealed,with the thermal expansion coefficients(TECs)along a-axis,c-axis,and the average value,equal toα_(a)=8.55(5)μK^(−1),α_(c)=10.23(5)μK^(−1),andα_(L)=9.14(5)μK^(−1),*** dilation along the c-axis was mainly dominated by out-plane V-P bonds be-tween layered *** to the pressure-dependent lattice parameters,the polycrystalline bulk modulus(B_(0)=185(9)GPa)and high compressibility anisotropy factor(B_(a)/B_(c)=1.64)was ***-while,the second-order elastic constants were calculated,and the elastic moduli,E=303 GPa,B=198 GPa,G=122 GPa,andν=0.246,were *** the weak connection between layer slabs by out-plane V1-P bond was revealed by the bond stiffness model,with a bond stiffness close to the M-A bond in MAx ***,good damage tolerance capability was predicted according to Paugh’s ratio(G/B=0.616)and Cauchy pressure(P_(a)=0 GPa,P_(c)=-7.5 GPa),even better than those of typical MAx *** discovery of V_(8)P_(6)C provides a new member of MAx-phase-like damage-tolerant ceramic with relatively low density,moderate thermal expansion,and anisotropic compressibility,and the unique lay-ered structure is inspiring for exploring new layered ternary ceramics.

关键词： New ternary carbide MAx phase Thermal expansion Elastic constants Anisotropy

Multi-scale simulation of columnar-to-equiaxed transition during laser selective melting of rare earth magnesium alloy

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Journal of Materials Science & Technology 2022年第24期119卷 11-24页

作者： W.L.Wang W.Q.Liu x.yang R.R.xu Q.y.dai School of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an 710055China

A model of coupling macro finite volume method(FVM) and cellular automata(CA) is proposed in this paper to explore the columnar-to-equiaxed transition(CET) during selective laser melting(SLM) of rare earth magnesium *** into account the impact of recoil pressure and Marangoni convection on the molten pool temperature field,the grain structure is *** suggested by the simulation results,with the undissolved Zr serving as heterogeneous nucleation sites,the liquid undercooled layer under the combined action of forced cooling,the temperature gradient and the liquid solute concentration gradient leads to *** considering the dissolution of Zr in magnesium matrix,the results demonstrate that the dissolution of element Zr is effective in significantly inhibiting the growth of columnar crystals and ensuring the sufficient constitutional supercooling(CS) required for *** addition,to raise the preheating temperature contributes to enhancing the outcome of nucleation and incresing the grain *** the interdependence model(IM),with the cooling rate gradually increasing in the SLM process of magnesium alloy,the nucleation-free zone(NFZ) reduces by decreasing the solute diffusion layer in the front of the solid/liquid(SL) interface and the temperature *** reduction in temperature gradient can promote undercooling for nucleation and facilitate the development of equiaxed *** simulation results are qualitatively verified as highly consistent through experimentation.

关键词： Multi-scale simulation Columnar-to-equiaxed transition Selective laser melting Rare earth magnesium alloy Constitutional supercooling

SIMULATION OF STEEL COIL HEAT TRANSFER IN HPH FURNACE

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Acta Metallurgica Sinica(English Letters) 2005年第5期18卷 647-652页

作者： M. y. Gu G. Chen M. C. Zhang x. C. dai School of Mechanical and Power Engineering Shanghai Jiaotong University Shanghai 200240 China School of Metallurgy and Material Anhui University of TechnologyMaanshan 243002 China Bao Shan Iron and Steel Corporation Ltd. Shanghai 201900 China

The mathematical model has been estublished for the simulation of steel coil＇s heat transfer during annealing thermal process in HPH （high performance hydrogen） furnace. The equivalent radial thermal conductivity is adopted by statistical analysis regression approach through the combination of a large quantity of production data collected in practice and theoretical analyses. The effect of the number of coils on circulating flow gas is considered for calculating the convection heat transfer coefficient, The temperature within the coil is predicted with the developed model during the annealing cycle including heating process and cooling process. The good consistently between the predicted results and the experimental data has demonstrated that the mathematical model established and the parameters identified by this paper are scientifically feasible and the effective method of calculation for coil equivalent radial heat transfer coefficient and circulating gas flow has been identified successfully, which largely enhances the operability and feasibility of the mathematic- model. This model provides a theoretical basis and an effective means to conduct studies on the impact that foresaid factors may imposed on the steel coil＇s temperature field, to analyze the stress within coils, to realize online control and optimal production and to increase facilily output by increasing heating and cooling rates of coils without producing higher thermal stress.

关键词： furnace equivalent radial thermal conductivity convection heat transfer coefficient simulation

Magnetization reversal of antiferromagnetically coupled perpendicular anisotropy films driven by current

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Journal of Materials Science & Technology 2018年第5期34卷 832-835页

作者： x.T.Zhao y.Q.Zhao W.Liu Z.M.dai T.T.Wang x.G.Zhao Z.D.Zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

By inserting an ultrathin Pt layer at Co/Ru interface,we established antiferromagnetic coupling with outof-plane magnetization in Co/Ru/Co film stacks fabricated by *** achieve configuration suitable for free layer,the magnetic properties of the stacks have been investigated by changing the thickness of Co,Ru and Pt layers using an orthogonal wedges *** is found that magnetic properties for upper Co layer thinner than 0.5 nm are sensitive to little change in Ru *** continuity of upper Co layer by slightly increasing the thickness can effectively increase the squareness of minor *** switching magnetization of synthetic antiferromagnetic（SAF） structure is achieved by DC current under an in-plane static magnetic field of ± 500 *** structure is very promising for free layer in spintronic application.

关键词： Magnetic materials Multilayer structure Wedge Exchange coupling Antiferromagnetic

Identifi cation of AFLP Makers Linked to Early-Bearing Gene in Walnut

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分子植物育种 2007年第2期5卷 266-268页

作者： J.x. Niu　 L. Wang　 y.x. dai　 R. Li x.K. yang 　J.Q. Lv Department of Horticulture Shihezi University Shihezi 832003 China

Amplified fragment length polymorphism (AFLP), a novel DNA fingerprinting technique based on polymerase chain reaction (PCR) with high discriminatory power, has the advantages of high effi ciency, rapidness, re-

关键词：胡桃基因研究分子标记植物性状

Rational design of AgGaS/ZnS/ZnS quantum dots with a near-unity photoluminescence quantum yield via double shelling scheme

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Journal of Materials Science & Technology 2024年第2期169卷 235-242页

作者： H.x.Lu H.Liu Z.Z.Fu y.y.Chen H.Q.dai Z.Hu W.L.Zhang R.Q.Guo Institute for Electric Light Sources School of Information Science and TechnologyFudan UniversityShanghai 200433China Institute of Future Lighting Academy for Engineering and TechnologyFudan UniversityShanghai 200433China yiwu Research Institute of Fudan University YiwuZhejiang 322000China Zhongshan-Fudan Joint Innovation Center Zhongshan 528437China

In this study,a two-step method was used to synthesize highly luminescent AgGaS/ZnS/ZnS quantum dots(QDs).In the first step,an inner ZnS shell was formed via a one-pot method,which resulted in a smaller lattice mismatch between the AgGaS core and the outer ZnS shell,thereby facilitating the formation of a thick outer *** the two-step shelling process,the synthesized AgGaS/ZnS/ZnS QDs showed an excellent photoluminescence quantum yield(PLQy)of 96.4%with a peak wavelength of 508 nm,repre-senting the highest PLQy reported thus far for AgGaS ***,the effect of halogen ions in Zn precursors on the shelling process was *** was proposed that the capacity of halogen ions to coordinate with the QDs influenced the balance between Zn cation diffusion and ZnS shelling ***,the ZnS shelling reaction was dominant when ZnCl_(2)was employed,while Zn cation diffusion was the dominant process under the I^(−)-rich *** work provides insights into the interfacial restructuring during the ZnS shelling and offers a clear map for the tailored synthesis of core/shell QDs.

关键词： AgGaS Quantum dots Photoluminescence Core/shell Alloyed core/shell interface

Control of dislocation density maximizing precipitation strengthening effect

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Journal of Materials Science & Technology 2022年第32期127卷 133-143页

作者： C.xu W.J.dai y.Chen Z.x.Qi G.Zheng y.D.Cao J.P.Zhang C.C.Bu G.Chen MIIT Key Laboratory of Advanced Metallic and Internetallic Materials Technology Engineering Research Center of Materials Behavior and DesignMinistry of EducationNanjing University of Science and TechnologyNanjing 210094China

The strength-ductility trade-off has been the most challenging problem for structural metals for *** strengthening is an ideal approach to enhance the strength without significantly sacrificing the *** nanoprecipitates have been successfully acquired by nanostructural design,but the number density of nanoprecipitates cannot be further *** attempted to enhance number density by introducing highly potent nucleation sites(e.g.,dislocations).However,there remains controversy over the influence of dislocations on the nucleation and growth of coherent nanoprecipitates with minimized nucleation ***,Cu-rich nanoprecipitates in an HSLA steel,as a typical type of coherent nanoprecipitates,are *** combining analytical calculation and experiments,we show that dislocations are harmful for the formation of large numbered Cu-rich nanoprecipitates in a certain density *** dislocations deprive solute atoms which decrease homogenous precipitation that cannot be compensated by the increase in heterogeneous *** such circumstance,Cu-rich nanoprecipitates have smaller number density but larger size and higher fraction of incoherent structures due to rapid Ostwald *** a result,by controlling dislocation density,the yield strength is increased by 24%without obvious loss in ductility as compared with traditional solution-quench-age *** work would help to optimize composition and processing routes that fully exploit the nanoprecipitation strengthening effect.

关键词： Cu-rich nanoprecipitates Crystallographic defects Nucleation Structural transformation Ostwald ripening

A neuron-immune circuit regulates neurodegeneration in the hindbrain and spinal cord of Arf1-ablated mice

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National Science Review 2023年第12期10卷 98-110页

作者： Guohao Wang Shuhan Jin Jiaqi Liu xu Li Peng dai yuetong Wang Steven x.Hou The Basic Research Laboratory Center for Cancer ResearchNational Cancer Institute at FrederickNational Institutes of Health Department of Cell and Developmental Biology at the School of Life Sciences State Key Laboratory of Genetic EngineeringInstitute of Metabolism and Integrative BiologyHuman Phenome Institute Department of Liver Surgery and Transplantation of Liver Cancer Institute at Zhongshan Hospital Fudan University

Neuroimmune connections have been revealed to play a central role in neurodegenerative diseases(NDs).However, the mechanisms that link the central nervous system(CNS) and peripheral immune cells are still mostly unknown. We recently found that specific ablation of the Arf1 gene in hindbrain and spinal cord neurons promoted NDs through activating the NLRP3 inflammasome in microglia via peroxided lipids and adenosine triphosphate(ATP) releasing. Here, we demonstrate that IL-1β with elevated chemokines in the neuronal Arf1-ablated mouse hindbrain and spinal cord recruited and activated γ δ T cells in meninges. The activated γ δ T cells then secreted IFN-γ that entered into parenchyma to activate the microglia-A1astrocyte-C3-neuronal C3a R neurotoxic pathway. Remarkably, the neurodegenerative phenotypes of the neuronal Arf1-ablated mice were strongly ameliorated by IFN-γ or C3 knockout. Finally, we show that the Arf1-reduction-induced neuroimmune-IFN-γ-gliosis pathway exists in human NDs, particularly in amyotrophic lateral sclerosis and multiple sclerosis. Together, our results uncover a previously unknown mechanism that links the CNS and peripheral immune cells to promote neurodegeneration.

关键词： neurodegenerative diseases disease-associated microglia γδ T cells reactive astrocyte IFN-γ C3