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synchronous improvement of mechanical properties and stress corrosion resistance by stress-aging coupled with natural aging pre-treatment in an Al-Zn-Mg alloy with high recrystallization fraction

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Journal of Materials science & Technology 2022年第26期121卷 40-51页

作者： d.Zhang H.C.Jiang Z.J.Cui d.s.yan Y.Y.song L.J.Rong CAs Key Laboratory of Nuclear Materials and safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China school of Materials science and Engineering University of Science and Technology of ChinaShenyang 110016China shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China shandong Key Laboratory of Advanced Aluminum Materials and Technology Binzhou 256606China

Enhancing the strength of Al-Zn-Mg alloys is critical to the weight-lightening of structural components in the application of high-speed trains and aerospace industries,while high stress corrosion cracking(sCC)susceptibility of Al-Zn-Mg alloys(especially the alloy with high recrystallization fraction)with high strength makes it *** this study,the influence of tensile stress-aging coupled with natural aging pre-treatment on the mechanical properties and sCC resistance of Al-Zn-Mg alloy with high recrystallization fraction has been *** results show that tensile stress-aging at 160℃can inhibit the dissolution of clusters/Guinier-Preston(GP)zones formed during long-term natural aging pre-treatment,which increases the number density of matrix precipitates(MPts),narrow the width of precipitate free zone(PFZ),and dramatically improve the mechanical properties of the experimental Al-Zn-Mg ***,the precipitation of the high density of MPts within the matrix will assume a large number of solute atoms during artificial aging,which will reduce the supplement of solute atoms to grain *** a result,the volume of anodic active grain boundary precipitates(GBPs)and the content of free solute atoms at grain boundaries are reduced,which reduces the possibility of initial nucleation and propagation of sCC *** coupled treatment method proposed in this study proves efficient in resolving the contradiction between the strength and sCC resistance in Al-Zn-Mg alloy.

关键词： Al-Zn-Mg alloy Natural aging stress-aging Precipitates stress corrosion cracking

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Relationship between CO_2 sensor Voltage Response and Phase Equilibrium of solid Electrolyte Na,K-β/β″-Al_2O_3

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Journal of Materials science & Technology 2003年第5期19卷 450-452页

作者： J.H.yanG H.Nafe F.Aldinger d.s.yan shanghaiInstituteofCeramics ChineseAcademyofSciencesShanghai200050China Max-Planck-InstitutfurMetallforschung PulvermetallurgischesLaboratoratiumHeisenbergstrasse570569StuttgartGermany

关键词： CO2 sensor Phase equilibrium solid electrolyte Na K-β/β'-Al2O3

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Two-stage double peaks ageing and its effect on stress corrosion cracking susceptibility of Al-Zn-Mg alloy

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Journal of Materials science & Technology 2018年第7期34卷 1250-1257页

作者： Y.L.Wang H.C.Jiang Z.M.Li d.s.yan d.Zhang L.J.Rong CAs Key Laboratory of Nuclear Materials and safety Assessment Institute of Metal Research Chinese Academy of Sciences school of Materials science and Engineering University of Science and Technology of China

different artificial two-stage ageing behaviors and their effect on stress corrosion cracking （sCC） susceptibility of AI-Zn-Mg alloy have been investigated. The experimental results show that two hardness peaks present on the second-stage ageing-hardening curve when the first-stage ageing is dealt with comparatively lower temperature than the conventional one. The first peak is caused by dispersive and evenly distributed G.P. zones, while η ′phases and coarsened G.P. zones contribute to the second peak. Tensile strength of experimental alloy raises 9.6% （33.2 MPa） and sCC susceptibility decreases 38.9% by applying the second peak ageing regime instead of conventional T73. AI-Zn-Mg alloy obtains high strength and sCC resistance due to its finely dispersive matrix precipitates （MPts）, coarsened and discontinuous grain boundary precipitates （GBPs）, as well as the narrow precipitate free zone （PFZ） in the second peak ageing condition. 2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials science ＆ Technology.

关键词： Al-Zn-Mg alloy Two-stage ageing double peaks ageing stress corrosion cracking (sCC) susceptibility Grain boundary precipitates (GBPs)

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Large eddy simulation study of 3d wind field in a complex mountainous area under different boundary conditions

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Journal of Zhejiang University-science A(Applied Physics & Engineering) 2024年第7期25卷 541-556页

作者： yan LI Lei yan Xuhui HE school of Civil Engineering Central South UniversityChangsha410075China National Engineering Research Center for High-speed Railway Construction Changsha410075China Hunan Provincial Key Laboratory for disaster Prevention and Mitigation of Rail Transit Engineering structures Changsha410075China

Large eddy simulations generally are used to predict 3d wind field characteristics in complex mountainous *** simulation boundary conditions,such as the height and length of the computational domain or the characteristics of inflow turbulence,can significantly impact the quality of *** this study,we examined these boundary conditions within the context of the mountainous terrain around a long-span cable-stayed bridge using a wind tunnel *** sizes of computational domains and turbulent incoming wind velocities were used in large eddy *** results show that when the height of the computational domain is five times greater than the height of the terrain model,there is minimal influence from the top wall on the wind field characteristics in this complex mountainous *** the length of the wake region of the computational domain has negligible effects on the wind *** in the inlet boundary reduces the length of the wake region on a leeward hill with a low slope,but has less impact on the mean wind velocity of steep hills.

关键词： Large eddy simulation(LEs) spectral representation method Recycling method High mountainous canyon Wind characteristics Atmospheric boundary layer Computational domain

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An Integral Method for solving dynamic Equations with Fluid–solid Coupling

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Acta Mechanica solida sinica 2024年第1期37卷 99-108页

作者： Xin Zhang Jie Liu Pu Xue shuowen yan Yahao Xu M.s.Zahran school of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China school of Mechatronical Engineering Beijing Institute of TechnologyBeijing 100081China department of Civil Engineering Military Technical CollegeCairo 11435Egypt

In this work,a new methodology is presented to mainly solve the fluid–solid interaction(FsI)*** methodology combines the advantages of the Newmark precise integral method(NPIM)and the dual neural network(dNN)*** NPIM is employed to modify the exponential matrix and loading vector based on the dNN integral *** involves incorporating the basic assumption of the Newmark-βmethod into the dynamic equation and eliminating the acceleration term from the dynamic equilibrium *** a result,the equation is reduced to a first-order linear equation ***,the PIM is applied to integrate the system step by step within the *** dNN method is adopted to solve the inhomogeneous term through fitting the integrand and the original function with a pair of neural networks,and the integral term is solved using the Newton–Leibniz *** examples demonstrate that the proposed methodology significantly improves computing efficiency and provides sufficient precision compared to the dNN *** is particularly evident when analyzing large-scale structures under blast loading conditions.

关键词： Newmark precise integral method(NPIM) dual neural networks(dNN) Fluid-solid interaction(FsI) dynamic time-history analysis Blast loading

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Electromagnetic characteristic analysis and design of a linear motor used for ultra-high-speed EMs maglev train

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science China(Technological sciences) 2024年第6期67卷 1957-1973页

作者： GAO Han sHI TingNa GAO XinMai LEI yanXiao yan dong GUO Liyan yan yan College of Electrical Engineering Zhejiang UniversityHangzhou310027China Zhejiang University Advanced Electrical Equipment Innovation Center Hangzhou311107China state Key Laboratory of High-speed Maglev Transportation Technology Qingdao266100China CRRC Qingdao sifang Co.Ltd. Qingdao266111China

The operating speed of the commercial electromagnetic suspension(EMs)maglev train has been over 430 km/h,making it the fastest means of land *** the increasing demands of people traveling,it is necessary to further improve the operating speed of maglev *** to examine whether the existing EMs system can meet the requirements of ultra-highspeed operation(more than 600 km/h),the electromagnetic characteristics of an EMs linear motor under the operating speed of 600–1000 km/h fed by a square-wave voltage supply is investigated in this ***,an electromagnetic field model of the EMs system under the square-wave voltage supply is established to investigate its electromagnetic performance,e.g.,the characteristics of phase current,the magnetic flux density,and the electromagnetic ***,the relationship between the harmonic components of the air-gap magnetic flux density and electromagnetic force is investigated using the two-dimensional fast Fourier transform(2d-FFT)to reveal the mechanism of electromagnetic force ***,to address the issues of excessive armature current density and significant electromagnetic force ripple,the linear motor is re-designed by enlarging the stator slot area and reshaping the mover's main magnetic ***,the Taguchi method is used to further improve the electromagnetic characteristics of the linear electric ***,the effectiveness of the proposed optimal design is validated by the finite-element analysis(FEA)based co-simulation.

关键词： ultra-high-speed maglev transportation electromagnetic suspension(EMs) linear motor electromagnetic force ripple suppression

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Topology Optimization of Two Fluid Heat Transfer Problems for Heat Exchanger design

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Computer Modeling in Engineering & sciences 2024年第8期140卷 1949-1974页

作者： Kun yan Yunyu Wang Jun yan school of Chemical Engineering Dalian University of TechnologyDalian116024China Jianghuai Advanced Technology Center Hefei230000China state Key Laboratory of structural Analysis for Industrial Equipment Department of Engineering MechanicsInternational Research Center for Computational MechanicsDalian University of TechnologyDalian116024China

Topology optimization of thermal-fluid coupling problems has received widespread *** article proposes a novel topology optimization method for laminar two-fluid heat exchanger *** proposed method utilizes an artificial density field to create two permeability interpolation functions that exhibit opposing trends,ensuring separation between the two fluid ***,a Gaussian function is employed to construct an interpolation function for the thermal conductivity ***,a computational program has been developed on the OpenFOAM platform for the topology optimization of two-fluid heat *** program leverages parallel computing,significantly reducing the time required for the topology optimization *** enhance computational speed and reduce the number of constraint conditions,we replaced the conventional pressure drop constraint condition in the optimization problem with a pressure inlet/outlet boundary *** 3d optimization results demonstrate the characteristic features of a surface structure,providing valuable guidance for designing heat exchangers that achieve high heat exchange efficiency while minimizing excessive pressure *** the same time,a new structure appears in large-scale topology optimization,which proves the effectiveness and stability of the topology optimization program written in this paper in large-scale calculation.

关键词： Topology optimization two fluid heat exchanger OpenFOAM large scale

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Rational surface charge engineering of haloalkane dehalogenase for boosting the enzymatic performance in organic solvent solutions

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Chinese Journal of Chemical Engineering 2024年第1期65卷 276-285页

作者： Yin Wu yan sun department of Biochemical Engineering School of Chemical Engineering and Technology and Key Laboratory of Systems Bioengineering and Frontiers Science Center for Synthetic Biology(Ministry of Education)Tianjin UniversityTianjin 300350China

Biocatalysis in organic solvents(Oss)has numerous important applications,but native enzymes in Oss often exhibit limited catalytic ***,we proposed a computation-aided surface charge engineering strategy to improve the catalytic performance of haloalkane dehalogenase dhaA in Oss based on the energetic analysis of substrate binding to the dhaA *** variants with enhanced Os resistance were obtained by replacing negative charged residues on the surface with positive charged residue(Arg).Particularly,a four-substitution variant E16R/E93R/E121R/E257R exhibited the best catalytic performance(five-fold improvement in Os resistance and seven-fold half-life increase in 40%(vol)dimethylsulfoxide).As a result,the overall catalytic performance of the variant could be at least 26 times higher than the wild-type *** spectroscopy and molecular dynamics simulation studies revealed that the residue substitution mainly enhanced Os resistance from four aspects:(a)improved the overall structural stability,(b)increased the hydrophobicity of the local microenvironment around the catalytic triad,(c)enriched the hydrophobic substrate around the enzyme molecule,and(d)lowered the contact frequency between Os molecules and the catalytic *** findings validate that computationaided surface charge engineering is an effective and ingenious rational strategy for tailoring enzyme performance in Oss.

关键词： surface charge engineering Organic solvent resistance Molecular dynamics simulation Haloalkane dehalogenase

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Flexible ultra-thin super-resolution endoscopy

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science China(Physics,Mechanics & Astronomy) 2024年第3期67卷 171-172页

作者： George s.d.Gordon department of Electrical and Electronic Engineering University of NottinghamNottingham NG7 2RDUK

In recent years, multimode fiber(MMF) has become an important tool for high-resolution endoscopic imaging in narrow channels(e.g., in the brain via needles or inside blood vessels) due to its high mode density and fine diameter, typically stacle to widespread deployment in applications is that realistic perturbations, including bending, twisting and changes in temperature, cause unacceptable image degradation.

关键词： fiber resolution typically

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The Multiple Roles of Autophagy in Neural Function and diseases

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Neuroscience Bulletin 2024年第3期40卷 363-382页

作者： yan-yan Li Zheng-Hong Qin Rui sheng department of Pharmacology and Laboratory of Aging and Nervous diseases Jiangsu Key laboratory of Neuropsychiatric DiseasesCollege of Pharmaceutical Sciences of Soochow UniversitySuzhou 215123China

Autophagy involves the sequestration and delivery of cytoplasmic materials to lysosomes,where proteins,lipids,and organelles are degraded and *** to the way the cytoplasmic components are engulfed,autophagy can be divided into macroautophagy,microautophagy,and chaperone-mediated ***,many studies have found that autophagy plays an important role in neurological diseases,including Alzheimer's disease,Parkinson's disease,Huntington's disease,neuronal excitotoxicity,and cerebral *** maintains cell homeostasis in the nervous system via degradation of misfolded proteins,elimination of damaged organelles,and regulation of apoptosis and ***-mTOR,Beclin 1,TP53,endoplasmic reticulum stress,and other signal pathways are involved in the regulation of autophagy and can be used as potential therapeutic targets for neurological ***,we discuss the role,functions,and signal pathways of autophagy in neurological diseases,which will shed light on the pathogenic mechanisms of neurological diseases and suggest novel targets for therapies.

关键词： Autophagy Neurodegenerative diseases Cerebral ischemia AMPK mTOR Beclin 1 TP53 Endoplasmic reticulum stress

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