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Structural characterization of the{1122}twin boundary and the corresponding stress accommodation mechanisms in pure titanium

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Journal of Materials Science & Technology 2021年第13期72卷 114-121页

作者： Bingqiang Wei song Ni Yong Liu min song State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

{11-22}compression twin plays an important role in accommodating deformation along the c axis of HCP ***,the studies on the interface structure of{11-22}twin boundary(TB),especially the twin tip,and the corresponding local stress release mechanism are still *** work studied the interface characters of{11-22}TB of a deformed pure titanium by transmission electron ***{11-22}TB presented serrated character,consisting of coherent twin boundary(CTB)and(0002)_(T)//(11-2-2)_(M)or(11-2-2)_(T)//(0002)_(M)steps,and the twin tip was fully composed of the basal-pyramidal(BPy)and pyramidal-basal(PyB)*** twin tip presents asymmetric morphology and the step height at the twin tip is much larger than that away from the twin *** types of local stress accommodation mechanisms were observed:zonal dislocation emission and hexagonal close packed structure to facecentered cubic structure *** zonal dislocation was produced by the dissociation of the1/3dislocation that was nucleated at the twin tip and the phase transformation was introduced by emission of Shockley partial dislocations from the{11-22}twin boundary.

关键词： {1122} twin Twin boundary Twinning dislocation Stress accommodation Titanium

A new digital algorithm for the velocity translation vector

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Science China(Information Sciences) 2013年第8期56卷 237-249页

作者： song min WU WenQi College of Mechatronics Engineering and Automation National University of Defense Technology

The error of the conventional sculling correction algorithm under maneuvers is analyzed through Taylor series expansion;a generalized error equation is *** frequency-series sculling algorithms in the digital algorithm for the velocity translation vector will cause the accuracy of the digital algorithm under maneuvers to decrease by one order in iteration time *** New sculling algorithms are developed and evaluated,which are as accurate as frequency-series sculling algorithms under vibrations,and are at least one order more accurate than frequency-series algorithms under *** new digital algorithms are constructed with the presented sculling algorithms for the velocity translation vector,which avoids the loss in accuracy of velocity translation vector under *** agree well with the analytical results.

关键词： sculling correction velocity translation vector maneuvers vibrations digital algorithm error evaluation

Effects of Mg and Ag elements on the aging precipitation of binary Al-Cu alloy

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Science China(Technological Sciences) 2006年第5期49卷 582-589页

作者： song min XIAO Daihong State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

The effect of trace elements Mg and Ag on the aging precipitation has been studied. It has been shown that both Mg and Ag have no obvious effect on the aging pre- cipitates but influence the nucleation and growth velocities of the precipitates in binary Al-Cu alloy if added separately. However, when Al-Cu alloy contains both elements Mg and Ag, Mg and Ag atoms strongly attract each other and form atom clusters along the matrix {111} planes. These atom clusters help the Cu atoms aggregate and nucleate het- erogeneously along the matrix {111} planes, which makes Mg atom clusters the optimized nucleation sites for Ω phase and inhibit the nucleation of θ′ phase.

关键词： Al-Cu alloy Ωphase θ′phase atom clusters

Optimization of risk policy and dividends with fixed transaction costs under interest rate

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Frontiers of Mathematics in China 2012年第4期7卷 795-811页

作者： Xin ZHANG min song School of Mathematical Sciences and LPMC Nankai University Tianjin 300071 China Department of Finance School of Economics Nankai University Tianjin 300071 China

In this paper, we consider the dividend optimization problem for a financial corporation with transaction costs. Besides the dividend control, the financial corporation takes proportional reinsurance to reduce risk and the surplus earns interest at the constant force p 〉 0. Because of the presence of fixed transaction costs, the problem becomes a mixed classical-impulse stochastic control problem. We solve this problem explicitly and construct the value function together with the optimal policy

关键词： Mixed classical-impulse control impulse control dividends quasivariational inequality transaction costs

Synergistically enhanced ORR and HER performance on Co-N-C coupled in-situ generated PtCo intermetallic

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Journal of Energy Chemistry 2025年第1期 721-729页

作者： Guanyu Luo min song Lulu An Xiao Huang Qian Zhang Chenhao Zhang Tao Shen Shuang Wang Deli Wang Key Laboratory of Material Chemistry for Energy Conversion and Storage (Huazhong University of Science and Technology) ministry of Education School of Chemistry and Chemical Engineering Huazhong University of Science and Technology

Integrating multi-scale sites in a composite catalyst is vital to realize efficient ***,a synergistic composite catalyst consisting of Co atomic sites and in-situ generated PtCo intermetallic compounds （IMCs）(o-PtCo@CoNC) is proposed through Co pre-anchoring and subsequent impregnation-reduction *** loading of Co atoms provides a chance for in-situ generating PtCo ordered intermetallic *** remaining Co single atoms and PtCo IMCs construct synergistic electrocatalytic *** from the ordered structure,synergistic effect of Pt Co IMCs and Co single atoms,o-PtCo@CoNC exhibits excellent electrocatalytic performance for oxygen reduction reaction （ORR） and hydrogen evolution reaction （HER） with mass activity of 1.21 A mgPt-1（at 0.9 V） and5.70 A mgPt-1（at an overpotential of 100 mV）,***,o-PtCo@CoNC delivers negligible loss of half-wave potential and overpotential during long-term stability test in acid solutions,with 13 mV decay after 50,000 potential cycles for ORR and a 2.7 mV decay after 20,000 potential cycles for *** integration strategy of single-atomic sites coupled IMCs paves the way for enhancing the activity and durability of Pt-based electrocatalysts.

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Phase transformation and structural evolution in a Ti-5at.%Al alloy induced by cold-rolling

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Journal of Materials Science & Technology 2020年第14期47卷 211-223页

作者： Bingqiang Wei song Ni Yong Liu Xiaozhou Liao min song State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China School of Aerospace Mechanical and Mechatronic EngineeringThe University of SydneySydneyNSW 2006Australia

The phase transformation,deformation mechanism and their correlation in a cold-rolled Ti-5 at.%Al alloy were *** types of phase transformations from a hexagonal close-packed(HCP)structure to a face-centered cubic(FCC)structure were observed:the basal-type(B-type)with an orientation relation-ship ofaxis of the HCP *** the proceeding of deformation,different deformation mechanisms were activated in the FCC and the HCP structures,respectively,which led to a faster grain refinement rate in the FCC structure than in the HCP *** twins with zero macroscopic strain were prevalent in the FCC domains produced by the B-type transformation,while deformation twins with macroscopic strain were normally observed in the FCC domains produced by the P-type *** is in accordance with the lattice mismatches produced during phase *** easy occurrence of deformation twinning in the FCC structure contributed significantly to the grain refinement *** addition,the interaction between neighboring FCC domains produced by the two types of phase transformations also accelerated the grain refinement process.

关键词： Ti-Al alloy Deformation mechanism Phase transformation Grain refinement Deformation twinning

The growth mechanisms of θ’ precipitate phase in an Al-Cu alloy during aging treatment

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Journal of Materials Science & Technology 2021年第2期61卷 25-32页

作者： Lin Gao Kai Li song Ni Yong Du min song State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

The plate-shaped θ’(Al2 Cu) precipitate acts as one of the primary strengthening phases in Al-Cu *** interface,especially the semicoherent interface,between Al-Cu solid solution(αAl) and θ’ phase contains a lot of clues about phase ***,these interfacial structures in an Al-Cu alloy after high-temperature and longtime aging have been analyzed in detail using atomic-scale high-angle annular dark-field scanning transmission electron microscopy and first-principles calculations in this *** was found that the lateral growth of θ’ precipitates is subjected to a combination of several major mechanisms under this aging *** for some common intermediate phases,two novel and striking structures were observed on the interface,which implies two alternative atomic diffusion mechanisms for θ’ precipitate *** one condition,the atomic diffusion from αAl to θ’ phase transformation adopts an interstitialcy mechanism based on additional Al *** the other condition,the diffusion is carried out through Al *** mechanisms are distinctly different from the previous theory based on direct diffusion of Cu *** first-principle calculations also confirm that these newfound diffusion processes are ene rgetically favored.

关键词： Al-Cu alloys Phase transformation Atomic-scaled imaging First-principles calculation

Effect of Ce on the thermal stability of the Ω phase in an Al-Cu-Mg-Ag alloy

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Rare Metals 2009年第2期28卷 156-159页

作者： song, min Xiao, Daihong Zhang, Fuqin State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China

This paper studies the effect of Ce on the thermal stability of the Ω phase in an Al-Cu-Mg-Ag alloy by TEM and tensile testing. It has been shown that Ce substantially increases the nucleation density of the Ω phase by acting as the heterogeneous nucleation center. Most impor-tantly,Ce improves the thermal stability of the Ω phase by decreasing the diffusion velocity of Cu atoms and increasing the energy barrier of the thickening ledge nucleation,thus improving the strength of the Al-Cu-Mg-Ag alloy at both ...

关键词： aluminium alloys Ω phase thermal stability Ce addition

Dynamics of the eco-environmental quality in response to land use changes in rapidly urbanizing areas: A case study of Wuhan, China from 2000 to 2018

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Journal of Geographical Sciences 2023年第2期33卷 245-265页

作者： HU Can song min ZHANG Anlu College of Land Management Huazhong Agricultural UniversityWuhan 430070China Sanford School of Public Policy Duke UniversityDurhamNC 27708USA School of Business Administration Zhongnan University of Economics and LawWuhan 430073China

The dramatic land use changes that occur in rapidly urbanized areas are important inducement to changes in the eco-environmental *** urban land use changes and their eco-environmental quality responses can provide theoretical support and a decision-making basis for sustainable and high-quality development in rapidly urbanizing *** Wuhan,China,as the study area,this paper extracts land use information using Landsat satellite remote sensing images and a support vector machine *** on this,a remote sensing-based ecological index evaluation model including humidity,greenness,dryness and heat is constructed to explore the changes in land use and their eco-environmental quality responses from 2000 to *** results show that(1)the structure,extent and spatial layout of land use in Wuhan from 2000 to 2018 have undergone tremendous changes under rapid urbanization,and the change of construction land is the greatest among all land use types;(2)the overall quality of eco-environment in Wuhan continues to improve as the scale of the improved eco-environment areas is greater than that of the deteriorated *** direction and magnitude of the impact of each indicator on the eco-environmental quality are different;(3)the improvement or deterioration of eco-environmental quality is closely related to the changes of different land use types within the study *** eco-environmental quality shows significant spatial heterogeneity,especially between the main urban areas and the suburban *** paper argues that reasonably adjusting the land use structure can serve to maintain or even improve the quality of the regional ***,this study puts forward suggestions for the coordinated development of land use and the eco-environment in rapidly urbanizing areas.

关键词： land use change eco-environmental quality remote sensing-based ecological index Wuhan China