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Molecular dynamics simulation of Tensile deformation and Fracture of γ-TiAl with and without surface defects

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Journal of Materials science & Technology 2016年第10期32卷 1033-1042页

作者： H.N.Wu d.s.xu H.Wang R.Yang Institute of Metal Research Chinese Academy of Sciences

Molecular dynamics simulation of uniaxial tension along [001] has been performed to study the influence of various surface defects on the initiation of plastic deformation and fracture of γ-TiAl single *** results indicate that brittle fracture occurs in perfect bulk; surfaces and edges will be detrimental to the strength of materials and provide dislocation nucleation site. The defects on surfaces and edges cause further weakening with various effects depending on defect type, size, position and orientation,while the edge dimples are the most influential. For γ-TiAl rods with surface dimples, dislocations nucleate from an edge of the rod when dimples are small, dimple dislocation nucleation occurs only when the dimples are larger than a strain rate dependent critical size. The dislocations nucleated upon [001]tension are super dislocations with Burger vectors 〈011] or 1/2 〈 112] containing four 1/6 〈 112 〉 partials. The effects of surface scratches are orientation and shape sensitive. scratches parallel to the loading direction have little influence, while sharp ones perpendicular to the loading direction may cause crack and thus should be avoided. This simulation also shows that, any type of surface defect would lower strength,and cause crack in some cases. But some may facilitate dislocation nucleation and improve ductility of TiAl if well controlled.

关键词： Intermetallic compounds superdislocation Fracture surface defects Molecular dynamics

dislocation self-interaction in TiAl:Evolution of super-dislocation dipoles revealed by atomistic simulations

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Journal of Materials science & Technology 2021年第10期69卷 138-147页

作者： Z.Zhen H.Wang C.Y.Teng C.G.Bai d.s.xu R.Yang Institute of Metal Research Chinese Academy of SciencesShenyang 110016China school of Materials science and Engineering University of Science and Technology of China.Shenyang 110016China school of Materials science and Engineering University of Shanghai for Science and TechnologyShanghai 200093China Laboratory of Fundamental Research AVIC China Aero-Polytechnology EstablishmentBeijing 100028.China

As one of the fundamental outcomes of dislocation self-interaction,dislocation dipoles have an important influence on the plastic deformation of materials,especially on fatigue and *** this work,superdislocation dipoles inγ-TiAl andα_(2)-Ti_(3)Al were systematically investigated by atomistic simulations,with a variety of dipole heights,orientations and annealing tempe *** results indicate that non-screw super-dipoles transform into locally stable dipolar or reconstructed cores at low temperature,while into isolated or interconnected point defect clusters and stacking fault tetrahedra at high temperature via short-range diffu ***-screw super-dipoles inγ-TiAl andα_(2)-Ti_(3)Al exhibit similar features as fcc and hcp metals,***,over long-term annealing where diffusion is significant,60°superdipoles inγ-TiAl are stable,whereas the stability of super-dipoles inα2-Ti3 Al increases with dipole height and orientation *** influence on mechanical properties can be well evaluated by integrating these results into mesoscale or constitutive models.

关键词： TiAl dislocation dipole Mechanical property Atomistic simulation

decomposition mechanisms of nuclear-grade cationic exchange resin by advanced oxidation processes:statistical molecular fragmentation model and dFT calculations

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Journal of Environmental sciences 2024年第1期135卷 433-448页

作者： Xiang Meng Pierre désesquelles Lejin xu department of Nuclear Engineering and Technology School of Energy and Power EngineeringHuazhong University of Science&TechnologyWuhan 430074China CNRs Laboratoire de Physique des Gaz et des PlasmasUniversitéParis-SaclayOrsay 91405France state Key Laboratory of Coal Combustion School of Energy and Power EngineeringHuazhong University of Science and TechnologyWuhan 430074China

The treatment and disposal of radioactive waste are presently facing great *** ion exchange resins have become a focus of attention due to their high production and serious environmental *** this paper,a simplified model of cationic exchange resin is proposed,and the degradation processes of cationic resin monomer initiated by hydroxyl radicals(·OH)are clarified by combining statistical molecular fragmentation(sMF)model and density functional theory(dFT)*** prediction of active sites indicates that the s-O bonds and the C-s bond of the sulfonic group are more likely to react during the *** meta-position of the sulfonic group on the benzene ring is the most active site,and the benzene ring without the sulfonic group has a certain *** C11-C14 and C17-C20 bonds,on the carbon skeleton,are the most easily *** is also found that dihydroxy addition and elimination reactions play a major role in the process of desulfonation,carbon skeleton cleavage and benzene ring *** decomposition mechanisms found through the combination of physical models and chemical calculations,provide theoretical guidance for the treatment of complex polycyclic aromatic hydrocarbons.

关键词： Cationic exchange resin statistical molecular fragmentation model density functional theory Hydroxyl radical decomposition mechanism

Riverine sulfate sources and behaviors in arid environment,Northwest China:Constraints from sulfur and oxygen isotopes

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Journal of Environmental sciences 2024年第3期137卷 716-731页

作者： Yifu xu Wenjing Liu Bing xu Zhifang xu Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Innovation Academy for Earth science Chinese Academy of SciencesBeijing 100029China University of Chinese Academy of sciences Beijing 100049China

The fate of riverine sulfate ion (sO_(4)^(2-)) and its environmental effects in arid environment are difficult to evaluate due to its complicated sources and strongly coupled behaviors with water cycle which is significantly modified by *** understand the sulfur cycle in aquatic systems in arid environment,the chemical and sulfur and oxygen isotopic compositions (δ^(34)s_(sO4)and δ^(18)O_(sO4)) of major rivers around the Badain Jaran desert,northwestern China,were *** rivers had averaged sO_(4)^(2-)content at 1336μmol/L,over 10times higher than the global *** δ^(34)s_(sO4)and δ^(18)O_(sO4)values ranged from-5.3‰to+11.8‰and+1.6‰to+12.8‰,*** end-member analysis and the inverse model showed that riverine sulfate was mainly derived from evaporites dissolution (0-87%),sulfide oxidation (13%-100%) and precipitation (0-33%),indicating heterogeneity in sulfur sources and behaviors along the river drainage with the lithology variations and climate *** isotopic tools combining with hydro-chemistry compositions could be applied to reveal sulfur cycle in arid *** on the calculation,sulfide oxidation plays the primary role in the headwater and upstream in the Qilian-Mountains area,where sulfide is widely *** the proportion of evaporites dissolution contributing to riverine sulfate is much higher in downstream in a drier ***,less precipitation and higher temperature can lead to more intensive evaporation,affecting the process of sulfide oxidation and enhancing the rates of evaporites dissolution and sulfate precipitation in the basin.

关键词： sulfur and oxygen isotopes source apportionment Inverse model Arid environment Inland rivers Northwestern China

Big Model strategy for Bridge structural Health Monitoring Based on data-driven, Adaptive Method and Convolutional Neural Network (CNN) Group

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structural durability & Health Monitoring 2024年第6期18卷 763-783页

作者： Yadong xu Weixing Hong Mohammad Noori Wael A.Altabey Ahmed silik Nabeel s.d.Farhan Nanjing Highway development Center Changzhou211106China Nanjing Zhixing Information Technology Co. Ltd.Nanjing210000China department of Mechanical Engineering California Polytechnic State UniversitySan Luis ObispoCA 93405USA department of Mechanical Engineering Faculty of EngineeringAlexandria UniversityAlexandria21544Egypt department of Civil Engineering Nyala UniversityP.O.Box 155NyalaSudan school of Civil Engineering University of LeedsLeedsLS29JTUK

This study introduces an innovative“Big Model”strategy to enhance Bridge structural Health Monitoring(sHM)using a Convolutional Neural Network(CNN),time-frequency analysis,and fine element *** ensemble methods,collaborative learning,and distributed computing,the approach effectively manages the complexity and scale of large-scale bridge *** CNN employs transfer learning,fine-tuning,and continuous monitoring to optimize models for adaptive and accurate structural health assessments,focusing on extracting meaningful features through time-frequency *** integrating Finite Element Analysis,time-frequency analysis,and CNNs,the strategy provides a comprehensive understanding of bridge *** diverse sensor data,sophisticated feature extraction,and advanced CNN architecture,the model is optimized through rigorous preprocessing and hyperparameter *** approach significantly enhances the ability to make accurate predictions,monitor structural health,and support proactive maintenance practices,thereby ensuring the safety and longevity of critical infrastructure.

关键词： structural Health Monitoring(sHM) bridges big model Convolutional Neural Network(CNN) Finite Element Method(FEM)

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

Aldehyde oxidase mediated enantioselective metabolic health risk of dinotefuran

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science China Chemistry 2024年第6期67卷 2079-2091页

作者： Liwei xu Xinxin xu Hua Kuang Chuanlai xu Xiaoling Wu state Key Laboratory of Food science and Resources Jiangnan UniversityWuxi214122China International Joint Research Laboratory for Biointerface and Biodetection and school of Food science and Technology Jiangnan UniversityWuxi214122China Collaborative Innovation center of Food safety and Quality Control in Jiangsu Province Jiangnan UniversityWuxi214122China

Chiral pollutants often pose significant differential environmental health *** this study,the biotransformation of chiral dinotefuran(dIN)and its enantioselective metabolic toxicity mechanisms have been systemically ***,reversedphase chromatography-high resolution mass spectrometry was developed to quantify the content of dIN R/s chiral enantiomer with pg level sensitivity,revealing a lower elimination rate constant(K_(e))of s-dIN(0.730 h^(-1))than R-dIN(0.746 h^(-1)).secondly,the interaction mechanism between dIN metabolism and important endogenous bioactive molecules,such as aldehyde oxidase(AOX)and neurotransmitters,was *** dIN nitro-group was converted into a guanidine group by the reducing site of nearby flavin adenine dinucleotide(FAd)in AOX with the preferred higher affinity of ***,the endogenous tryptophan(Trp)aldehyde metabolic intermediate,5-hydroxyindoleacetaldehyde(5-HIAL),provides a persistent electron donor for dIN reduction via the oxidation-catalyzed site in AOX,resulting in remarkable up-regulation of monoamine neurotransmitters such as serotonin and ***,the higher level of neurotransmitters further mediated dysregulation of oxylipin homeostasis via the serotonergic pathway,where s-dIN exhibited more pronounced liver lipid damage and environmental health risk with the accumulated lipid biomarkers,oxidized triglyceride(OxTG)and oxidized sphingomyelin(OxsM).This study elucidates the AOX-mediated enantioselectivity metabolic pathway of dIN,providing a new analytical method for chiral pollutants and paves the way for their health risk assessments.

关键词： neonicotinoid dinotefuran enantiomer aldehyde oxidase metabolomics health risk

Investigation and optimization of high-valent Ta-doped srFeO_(3-δ)as air electrode for intermediate-temperature solid oxide fuel cells

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International Journal of Minerals,Metallurgy and Materials 2024年第9期31卷 2102-2109页

作者： shanshan Jiang Hao Qiu shaohua xu Xiaomin xu Jingjing Jiang Beibei Xiao Paulo sérgio Barros Juliao) Chao su daifen Chen Wei Zhou school of Energy and Power Jiangsu University of Science and TechnologyZhenjiang 212100China WA school of Mines:Minerals Energy and Chemical EngineeringCurtin UniversityPerth WA6102Australia Institute of Analysis and Testing Beijing Academy of Science and TechnologyBeijing 100089China state Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing 211816China

To explore highly active and thermomechanical stable air electrodes for intermediate-temperature solid oxide fuel cells(ITsOFCs),10mol%Ta5+doped in the B site of strontium ferrite perovskite oxide(srTa_(0.1)Fe_(0.9)O_(3-δ),sTF)is investigated and *** effects of Ta^(5+)doping on structure,transition metal reduction,oxygen nonstoichiometry,thermal expansion,and electrical performance are evaluated *** 10mol%Ta^(5+)doping,the thermal expansion coefficient(TEC)decreased from 34.1×10^(-6)(srFeO_(3-δ))to 14.6×10^(-6) K^(-1)(sTF),which is near the TEC of electrolyte(13.3×10^(-6) K^(-1) for sm_(0.2)Ce_(0.8)O_(1.9),sdC),indicates excellent thermomechanical *** 550-750℃,sTF shows superior oxygen vacancy concentrations(0.262 to 0.331),which is critical in the oxygen-reduction reaction(ORR).Oxygen temperature-programmed desorption(O_(2)-TPd)indicated the thermal reduction onset temperature of iron ion is around 420℃,which matched well with the inflection points on the thermos-gravimetric analysis and electrical conductivity *** 600℃,the sTF electrode shows area-specific resistance(AsR)of 0.152Ω·cm^(2) and peak power density(PPd)of 749 mW·cm^(-2).ORR activity of sTF was further improved by introducing 30wt%sm_(0.2)Ce_(0.8)O_(1.9)(sdC)powder,sTF+sdC composite cathode achieving outstanding AsR value of 0.115Ω·cm2 at 600℃,even comparable with benchmark cobalt-containing cathode,Ba_(0.5)sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ)(BsCF).distribution of relaxation time(dRT)analysis revealed that the oxygen surface exchange and bulk diffusion were improved by forming a composite *** 650℃,sTF+sdC composite cathode achieving an outstanding PPd of 1117 mW·cm^(-2).The excellent results suggest that sTF and sTF+sdC are promising air electrodes for IT-sOFCs.

关键词： strontium ferrite-based perovskite Ta doping composite cathode intermediate-temperature solid oxide fuel cells

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