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Analysis of a permeable interface crack in elastic dielectric/piezoelectric bimaterials

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Acta Mechanica Sinica 2007年第6期23卷 681-687页

作者： Qun Li Yiheng Chen school of aerospace,xi’an jiaotong university,xi’an 710049,china school of aerospace Xi’an Jiaotong University Xi’an 710049 China

A permeable interface crack between elasticdielectric material and piezoelectric material is studied basedon the extended Stroh’s *** by strong engi-neering demands to design new composite materials,theauthors perform numerical analysis of interface crack tip sin-gularities and the crack tip energy release rates for 35 typesof dissimilar bimaterials,respectively,which are constructedby five kinds of elastic dielectric materials:Epoxy,Poly-mer,Al;O;.SiC,and Si;N;and seven kinds of practicalpiezoelectric ceramics:PZT-4,BaTiO;,PZT-5H,PZT-6B,PZT-7A,P-7,and PZT-PIC 151,*** elasticdielectric material with much smaller permittivity than com-mercial piezoelectric ceramics is treated as a special trans-versely isotropic piezoelectric material with extremely *** present investigation shows that thestructure of the singular field near the permeable interfacecrack tip consists of three singularities:r;and r;,which is quite different from that in the impermeable inter-face *** can be concluded that different far field load-ing cases have significant influence on the near-tip fracturebehaviors of the permeable interface *** on thepresent theoretical treatment and numerical analysis,the elec-tric field induced crack growth is well explained,which pro-vides a better understanding of the failure mechanism inducedfrom interface crack growth in elastic dielectric/piezoelectricbimaterials.

关键词： Elastic dielectric Piezoelectric Permeable Interface crack Singularity Energy release rate

Homological Transfer between Additive Categories and Higher Differential Additive Categories

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Acta Mathematica Sinica,English Series 2024年第5期40卷 1325-1344页

作者： xi TANG Zhao Yong HUANG school of Science Guilin University of Aerospace TechnologyGuilin 541004P.R.China Department of Mathematics Nanjing UniversityNanjing 210093P.R.China

Given an additive category C and an integer n≥*** higher differential additive category consists of objects X in C equipped with an endomorphism ϵ_(X)satisfying ϵ_(X)^(n).Let R be a,finite-dimensional basic algebra over an algebraically closed field and T the augmenting functor from the category of finitely generated left R-modules to that of finitely generated left R/(t^(n))-*** is proved that a finitely generated left R-module M isτ-rigid(respectively,(support)τ-tilting,almost completeτ-tilting)if and only if so is T(M)as a left R[t]/(t^(n))-***,R isτm-selfinjective if and only if so is R[t]/(t^(n)).

关键词： Higher differential objects Wakamatsu tilting subcategories G_(ω)-projective modules sup-portτ-tilting modules τ_(m)-selfinjective algebras precluster tilting subcategories

A Systematic Analysis of Early Life Exposure to the Chinese Famine(1959-1961)and the Health of Older Adults-china,2008-2023

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china CDC weekly 2024年第11期6卷 203-207,I0001-I0003页

作者： Chi Shen xi Chen school of Public Policy and Administration Xi’an Jiaotong UniversityXi’an CityShaanxi ProvinceChina Department of Health Policy and Management Yale School of Public HealthNew HavenCTU.S Department of Economics Yale UniversityNew HavenCTU.S

What is already known about this topic?There is mounting evidence indicating that the aging process initiates during early life stages,with in utero the individual’s environment playing a significant ***,it is crucial to comprehend the enduring effects of early life circumstances on health in old *** is added by this report?In this study,we conducted a meta-analysis to examine the effects of the Chinese Famine(1959–1961)on the health of older *** also explored potential mechanisms underlying these *** are the implications for public health practice?The complex interplay between early life circumstances,multiple health-related sectors,and healthy aging necessitates a comprehensive life-course approach and strategic interventions to enhance public health in an aging society.

关键词： life aging mount

“Blocking and rebalance”mechanism-guided design strategies of bimetallic doped 2D a-phosphorus carbide as efficient catalysts for N_(2) electroreduction

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Journal of Energy Chemistry 2024年第10期97卷 68-78,I0003页

作者： Cheng He Jianglong Ma Shen xi Wenxue Zhang State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi'an Jiaotong UniversityXian 710049ShanxiChina school of Materials Science and Engineering Chang'an UniversityXi'an 710064ShaanxiChina

Compared to single atom catalysts(SACs),the introduction of dual atom catalysts(DACs)has a significantly positive effect on improving the efficiency in the electrocatalytic nitrogen reduction reaction(NRR)which provides an environmental alternative to the Haber-Bosch ***,the research on the mechanism and strategy of designing bimetallic combinations for better performance is still in its early ***,based on"blocking and rebalance"mechanism,45 combinations of bimetallic pair dopedα-phosphorus carbide(TM_(A)TM_(B)@PC)are investigated as efficient NRR catalysts through density functional theory and machine learning *** a multi-step screening,the combinations of TiV,TiFe,MnMo,and FeW exhibit highly efficient catalytic performance with significantly lower limiting potentials(-0.17,-0.18,-0.14,and-0.30 V,respectively).Excitingly,the limiting potential for CrMo and CrW combinations is 0 V,which are considered to be extremely suitable for the NRR *** mechanism of"blocking and rebalance"is revealed by the exploration of charge transfer for phosphorus atoms in electron blocking ***,the descriptorφis proposed with machine learning,which provides design strategies and accurate prediction for finding efficient *** work not only offers promising catalysts TM_(A)TM_(B)@PC for NRR process but also provides design strategies by presenting the descriptorφ.

关键词： DACs Nitrogen reduction reaction 2D a-phosphorus carbide Inherent attributes Machine learning

Transforming liquid flow fuel cells to controllable reactors for highlyefficient oxidation of 5-hydroxymethylfurfural to 2, 5-furandicarboxylic acid at low temperature

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Journal of Energy Chemistry 2024年第3期90卷 621-631,I0014页

作者： Ye Qiang xi Liu Denghao Ouyang Zhao Jiang Xuebing Zhao Key Laboratory of Industrial Biocatalysis Ministry of EducationTsinghua UniversityBeijing 100084China Institute of Applied Chemistry Department of Chemical EngineeringTsinghua UniversityBeijing 100084China school of Chemical Engineering and Technology Xi'an Jiaotong UniversityXi'an 710049ShaanxiChina

Highly-efficient oxidation of 5-hydroxymethylfurtural(HMF) to 2,5-furandicarboxylic acid(FDCA) at low temperature with air as the oxidant is still ***,inspired by the respirato ry electron transport chain(ETC) of living cells mediated by electron carriers,we constructed artificial ETCs and transformed liquid flow fuel cells(LFFCs) to flexible reactors for efficient oxidation of HMF to produce FDCA under mild *** LFFC reactor employed an electrodeposition modified nickel foam as an anode to promote HMF oxidation and(VO_(2))_(2)SO_(4) as a cathode electron carrier to facilitate the electron transfer to *** reaction rate could be easily controlled by selecting the anode catalyst,adjusting the external loading and changing the cathodic electron carrier or oxidants.A maximal power density of 44.9 mW cm^(-2) at room temperature was achieved,while for FDCA production,short-circuit condition was preferred to achieve quick transfer of *** a single batch operation with 0.1 M initial HMF,FDCA yield reached 97.1%.By fed-batch operation,FDCA concentration reached 144.5 g L^(-1) with a total yield of 96%.Ni^(2+)/Ni^(3+) redox couple was the active species mediating the electron transfer,while both experimental and DFT calculation results indicated that HMFCA pathway was the preferred reaction mechanism.

关键词： 5-Hydroxymethylfurfural 2 5-Furandicarboxylic acid Electrodeposition Electron transport chain Liquid flow fuel cell

Characterization of Fe-containing particles in Chengdu,southwest china,using single-particle aerosol mass spectrometry

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Journal of Environmental Sciences 2024年第2期136卷 110-120页

作者： Renjiang He Junke Zhang Luyao Chen Wei Zhang Yingwei xi school of Public Health Southwest Medical UniversityLuzhou 646000China Faculty of Geosciences and Environmental Engineering Southwest Jiaotong UniversityChengdu 611756China Sichuan Environmental Monitoring Center Chengdu 610074China

Single-particle aerosol mass spectrometry was used to study the characteristics of Fecontaining particles during winter in Chengdu,southwest *** mass concentrations of PM_(2.5)and PM_(10)during the study period were 64±38 and 89±49μg/m~3,respectively,and NO_(2)and particulate matter were high compared with most other regions of *** Fecontaining particles were divided into seven categories with different mass spectra,sources and aging *** highest contribution was from Fe mixed with carbonaceous components(Fe-C,23.1%)*** was more mixed with sulfate than nitrate and therefore the contribution of Fe mixed with sulfate(Fe-S,20.7%)particles was higher than that of Fe mixed with nitrate(Fe-N,12.5%)*** contributions from Fe-containing particles related to primary combustion were high in the small particle size range,whereas aged Fecontaining particles and dust-related particles were mostly found in the coarse particle size *** air masses mainly originated from the west and east of Chengdu,and the corresponding PM_(2.5)concentrations were 79±36 and 55±36μg/m~3,*** west and east air masses showed stronger contributions of Fe-containing particles related to biomass burning(Fe-B)and fossil fuel combustion(Fe-C and Fe-S)particles,*** southwest area contributed the most Fe-containing *** assessments of the effects of Fe-containing particles during heavy pollution period should pay more attention to Fe-C and Fe-S ***-reduction of Fe-containing particles should consider both local emissions and short-distance transmission from the surrounding areas.

关键词： Fe-containing particles Particle composition Potential source areas Evolution Chengdu

Investigation of the crack problem in non-local piezoelectric materials under combined electromechanical loadings

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Acta Mechanica Sinica 2009年第2期25卷 219-225页

作者： Q. Li Y. Chen school of aerospace, xi’an Jiao-Tong university,710049 xi’an, china school of aerospace Xi’an Jiao-Tong University 710049 Xi’an China

The present investigation of the crack problem in piezoelectric materials is performed based on the non-local theory. After some manipulations, the impermeable crack, the permeable crack （the crack gap is full of NaCI solution）, and the semi-permeable crack （the crack gap is full of air or silicon oil） are reduced to a uniform formulation by assuming the normal electric displacement on the crack surfaces to be an unknown variable. Thus, a triple integral equation with the unknown normal electric displacement is established. By using the Newton iterative method and solving the triple integral equation, it is found that the normal electric displacement on the crack surfaces is no longer a constant as determined by previous studies, rather, it depends upon the remote combined electromechanical loadings. Numerical results of the stresses and electric displacement fields show that there are no singularities at the crack tips so that the stresses remain finite. It is of great significance that the concrete electric boundary condition on the crack surfaces exerts significant influence on the near-tip fields and in this way plays an important role in evaluating the crack stability in the non-local piezoelectric materials. More specifically, the impermeable crack model always overestimates the finite stresses at the crack tips, whereas the permeable crack model always underestimates them.

关键词： Crack Non-local piezoelectric materialsImpermeable Permeable Semi-permeable

Hybrid state estimation and model-set design of invariable-structure semi-ballistic reentry vehicle

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Science china(Information Sciences) 2011年第4期54卷 812-823页

作者： LIANG YongQi 1,2 & HAN ChongZhao 1 1 MOE KLINNS Lab,SKLMSE Lab,Institute of Integrated Automation,school of Electronics and Information Engineering,xi’an jiaotong university,xi’an 710049,china 2 school of aerospace,xi’an jiaotong university,xi’an 710049,china 1. MOE KLINNS Lab SKLMSE Lab Institute of Integrated Automation School of Electronics and Information Engineering Xi’an Jiaotong University Xi’an 710049 China2. School of Aerospace Xi’an Jiaotong University Xi’an 710049 China

Multiple-model approach is one of the main streams for hybrid *** difficulty of this approach to estimate the hybrid state of the semi-ballistic reentry vehicle (SBRV) is model-set *** paper proposes a quasi-Monte Carlo model set that can ensure the estimator near-optimal in the sense of minimum mean square error (MMSE).The SBRV has a high nonlinearity and its mode is spanned by multiple parameters with known *** design methods and characteristics of the quasi-Monte Carlo model set are *** proposed model set has a higher accuracy than the model-set generated by the Monte Carlo *** theoretical analysis and simulation results show the effectiveness and reasonability of the newly designed model set.

关键词： semi-ballistic reentry vehicle hybrid estimation model-set design Monte Carlo method quasi-Monte Carlo method

ANALYSIS OF CRACK-TIP SINGULARITIES FOR AN INTERFACIAL PERMEABLE CRACK IN METAL/PIEZOELECTRIC BIMATERIALS

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Acta Mechanica Solida Sinica 2007年第3期20卷 247-257页

作者： Li Qun Chen Yiheng~* (school of aerospace,xi’an Jiao-Tong university,xi’an 710049,china) school of aerospace Xi''an Jiao-Tong University Xi''an 710049 China

By modeling metal as a special piezoelectric material with extremely small piezoelec- tricity and extremely large permittivity,we have obtained the analytical solutions for an interfacial permeable crack in metal/piezoelectric bimaterials by means of the generalized Stroh formalism. The analysis shows that the stress fields near a permeable interfacial crack tip are usually with three types of singularities:r;and r;.Further numerical calculation on the oscillatory indexεare given for 28 types of metal/piezoelectric bimaterials combined by seven commercial piezoelectric materials: PZT-4,BaTiO;,PZT-5H,PZT-6B,PZT-7A,P-7 and PZT-PIC 151 and four metals:copper,silver,lead and aluminum,*** explicit expressions of the crack tip energy release rate（ERR）and the crack tip generalized stress intensity factors（GSIF）are *** is found that both the ERR and GSIF are independent of the electric displacement loading,although they seriously depends on the mechanical loadings.

关键词： interfacial permeable crack metal/piezoelectric bimaterials energy release rate intensity factor