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National Science Review 2023年第11期10卷 103-109页

作者： zhi-fan zhang Zhen-Gang Zhu Gang Su School of Physical Sciences University of Chinese Academy of Sciences School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of Sciences CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Kavli Institute for Theoretical Sciences University of Chinese Academy of Sciences

Recently, charge or spin nonlinear transport with nontrivial topological properties in crystal materials has attracted much attention. In this paper, we perform a comprehensive symmetry analysis for all 122 magnetic point groups(MPGs) and provide a useful dictionary for charge and spin nonlinear transport from the Berry curvature dipole, Berry connection polarizability and Drude term with nontrivial topological *** results are obtained by conducting a full symmetry investigation of the matrix representations of six nonlinear response tensors. We further identify every MPG that can accommodate two or three of the nonlinear tensors. The present work gives a solid theoretical basis for an overall understanding of the second-order nonlinear responses in realistic materials.

关键词： nonlinear response magnetic point group matrix representation

Numerical research on slamming characteristics of aircraft landing on water

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Journal of Hydrodynamics 2023年第1期35卷 171-184页

作者： Dao-sheng Ning Ya-jun Shi Gui-yong zhang Heng Wang Huan Hu zhi-fan zhang State Key Laboratory of Structural Analysis for Industrial Equipment School of Naval Architecture EngineeringDalian University of TechnologyDalian116024China China Ship Scientific Research Center Wuxi200136China Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration Shanghai200240China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

In order to investigate the impact characteristic of an aircraft landing on water,a computational fluid dynamics(CFD)simulation is conducted to explore the slamming characteristics of the NACA TN 2929 A *** flow around the model is solved by using Reynolds-averaged Navier-Stokes equations with the shear stress transport(SST)k—ωturbulence model,based on finite volume method(FVM).The free surface is captured by using the volume of fluid(VOF)method,and the aircraft impact process is realized with help of overset mesh ***,the effects of horizontal and vertical velocities and initial pitch angle on the slamming load,attitude change,impact pressure and flow field evolution are *** results reveal that the horizontal velocity has a considerable influence on whether the aircraft’s horizontal tail hits the water,and further affects the maximum vertical load as well as the maximum pitch angle throughout the impact *** vertical velocity determines the slamming load before the horizontal tail strikes the water,while the horizontal velocity has a significant effect on the load after the horizontal tail hits the water.A smaller initial pitch angle results in not only a heavier slamming load but also a more dramatic change of the posture after the aircraft impacts the *** impact pressure of the aircraft is maximized at the junction of the approaching surface of the fuselage and the free *** some cases,the pressure is also concentrated on the undersurface of the horizontal tail.

关键词： Computational fluid dynamics(CFD) aircraft landing water entry slamming load motion attitude change

Application of GNSS-PPP on Dynamic Deformation Monitoring of Offshore Platforms

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China Ocean Engineering 2024年第2期38卷 352-361页

作者： YU Li-na XIONG Kuan GAO Xi-feng LI zhi fan Li-long zhang Kai Institute of Ocean Energy and Intelligent Construction Tianjin University of TechnologyTianjin 300384China China Railway Construction Bridge Engineering Bureau Group Co.LTD Tianjin 300300China School of Civil Engineering Tianjin UniversityTianjin 300072China Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic UniversityHong KongChina State Key Laboratory of Precision Blasting Jianghan UniversityWuhan 430056China

The real-time dynamic deformation monitoring of offshore platforms under environmental excitation is crucial to their safe *** Global Navigation Satellite System-Precise Point Positioning(GNSS-PPP)has been considered for this purpose,its monitoring accuracy is relatively ***,the influence of background noise on the dynamic monitoring accuracy of GNSS-PPP remains ***,it is imperative to further validate the feasibility of GNSS-PPP for deformation monitoring of offshore *** address these concerns,vibration table tests with different amplitudes and frequencies are *** results demonstrate that GNSS-PPP can effectively monitor horizontal vibration displacement as low as±30 mm,which is consistent with ***,the spectral characteristic of background noise in GNSS-PPP is similar to that of GNSS-RTK(Real Time Kinematic).Building on this observation,an improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN)has been proposed to de-noise the data and enhance the dynamic monitoring accuracy of *** monitoring application research is also undertaken,successfully extracting and analyzing the dynamic deformation of an offshore platform structure under environmental excitation using GNSS-PPP monitoring in conjunction with improved CEEMDAN *** comparing the de-noised dynamic deformation trajectories of the offshore platform during different periods,it is observed that the platform exhibits reversible alternating vibration responses under environmental excitation,with more pronounced displacement deformation in the direction of load *** research results confirm the feasibility and potential of GNSS-PPP for dynamic deformation monitoring of offshore platforms.

关键词： GNSS-PPP offshore platform dynamic deformation monitoring improved CEEMDAN de-noising

Optimization of microstructure design for enhanced sensing performance in flexible piezoresistive sensors

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Journal of Advanced Ceramics 2024年第6期13卷 711-728页

作者： Xinghao fan Hailong Hu Bin Liao Yaqi zhang fan zhang School of Minerals Processing and Bioengineering Central South UniversityChangsha 410083China Research Institute of Aerospace Technology Central South UniversityChangsha 410083China

Flexible piezoresistive strain sensors have received significant attention due to their diverse applications in monitoring human activities and health,as well as in robotics,prosthetics,and human–computer interaction *** the various flexible sensor types,those with microstructure designs are considered promising for strain sensing due to their simple structure,high sensitivity,extensive operational range,rapid response time,and robust *** review provides a concise overview of recent advancements in flexible piezoresistive sensors based on microstructure design for enhanced strain sensing performance,including the impact of microstructure on sensing mechanisms,classification of microstructure designs,fabrication methods,and practical ***,this review delves into the analysis of piezoresistive sensor sensing mechanisms and performance parameters,exploring the relationship between microstructure design and performance ***,an in-depth discussion is presented,focusing on the primary themes of microstructure design classification,process selection,performance characteristics,and specific *** review employs mathematical modeling and hierarchical analysis to emphasize the directionality of different microstructures on performance enhancement and to highlight the performance advantages and applicable features of various microstructure *** conclusion,this review examines the multifunctionality of flexible piezoresistive sensors based on microstructure design and addresses the challenges that still need to be overcome and improved,such as achieving a wide range of stretchability,high sensitivity,and robust *** review summarizes the research directions for enhancing sensing performance through microstructure design,aiming to assist in the advancement of flexible piezoresistive sensors.

关键词： microstructure design sensing performance flexible piezoresistive strain sensors microsensing mechanism

P-symmetric Subharmonic Solutions for Nonlinear Hamiltonian Systems

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Acta Mathematica Sinica,English Series 2024年第6期40卷 1388-1408页

作者： Duan zhi zhang zhi Hao ZHAO School of Mathematical Sciences Nankai UniversityTianjin 300071P.R.China

In this paper,we prove that for each positive k≡1 mod m there exists a P-symmetric kmτ-periodic solution xk for asymptotically linear mτ-periodic Hamiltonian systems,which are nonautonomous and endowed with a *** the P-symmetric Hamiltonian function is semi-positive,one can prove,under a new iteration inequality of the Maslov-type P-index,that xk_(1) and xk_(2) are geometrically distinct for k_(1)/k_(2)≥(2n+1)m+1;and xk_(1),xk_(2) are geometrically distinct for k_(1)/k_(2)≥m+1 provided xk_(1) is non-degenerate.

关键词： P-symmetric subharmonic Hamiltonian systems Maslov-type index theory iteration inequality asymptotically linear

Synergistic effect between Er-doped MoS_(2)nanosheets and interfacial Mo-N coupling phases for enhanced electrocatalytic hydrogen evolution

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Rare Metals 2024年第3期43卷 1301-1308页

作者： Nian-Peng Li Lei zhang Hua zhang fan-Fei Min Lei Wang Sam Toan Xi-Jun Liu Guang-zhi Hu State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines School of Materials Science and EngineeringAnhui University of Science and TechnologyHuainan232001China Donghai Laboratory Zhoushan316021China Department of Chemical Engineering University of Minnesota-DuluthDuluthMN55812USA School of Ecology and Environmental Science Institute for Ecological Research and Pollution Control of Plateau LakesYunnan UniversityKunming650504China MOE Key Laboratory of New Processing Technology for Non-Ferrous Metals and Materials Guangxi Key Laboratory of Processing for Non-Ferrous Metals and Featured MaterialsGuangxi UniversityNanning530004China

Hydrogen production via electrochemical water splitting is a promising and green *** one of the most representative transition metal sulfides layered materials,Molybdenum disulfide(MoS_(2))has immense potential for the hydrogen evolution reaction(HER).We successfully prepared a nitrogen-doped carbon(NC)in situ-grown erbium-doped MoS_(2)polyhedral structure(Er-MoS_(2)/NC)that incorporates an interfacial Mo-N coupling phase.

关键词： hydrogen interfacial coupling

Enhanced memristor performance via coupling effect of oxygen vacancy and ferroelectric polarization

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Journal of Materials Science & Technology 2024年第4期171卷 139-146页

作者： zhi Yun Yue zhi Dong zhang Zhan Jie Wang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China

As a new type of nonvolatile memory,the resistive memristor has broad application prospects in in-formation storage and neural computing based on its excellent resistive switching(RS)*** present,it is still a great challenge to improve both ferroelectric polarization and leakage current to achieve a high RS on/offratio of ferroelectric ***,epitaxial Pb(Zr_(0.40)Ti_(0.60))O_(3)(PZT)thin films with low content Ca doping were deposited on the Nb:SrTiO_(3)substrate to prepare PCZT/NSTO het-erostructures and their RS behaviors were *** research findings show that compared with pure PZT film,the ferroelectric polarization of 1-mol%-Ca-doped PZT film is slightly improved,while the leak-age current is increased by three orders of ***,the RS on/offratio reaches 2.5×10^(5),about three orders of magnitude higher than pure PZT *** theoretical analysis reveals that the RS behavior of PCZT/NSTO heterostructures is controlled by the PCZT/NSTO interfacial barrier and the space charge-limited current *** results demonstrate that the ferroelectricity and electricity of ferroelectric thin films can be improved simultaneously by doping low-content Ca ions to increase the RS performance,which provides a good reference for the development of high-performance ferroelectric memristor devices.

关键词： Ferroelectric memristor Ca-doped PZT Ferroelectric polarization Oxygen vacancies Resistive switching

Soliton resolution and asymptotic stability of N-solutions for the defocusing Kundu–Eckhaus equation with nonzero boundary conditions

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Communications in Theoretical Physics 2024年第1期76卷 1-6页

作者： Engui fan Yanxi zhang School of Mathematical Sciences and Key Laboratory of Mathematics for Nonlinear Science Fudan UniversityShanghai200433China Tianjin Xinhua High School No.99 machang RoadTianjin300204China

In this paper,we address interesting soliton resolution,asymptotic stability of N-soliton solutions and the Painleve asymptotics for the Kundu-Eckhaus(KE)equation with nonzero boundary conditions iq_(t)+q_(xx)-2(l|q|^(2)-1)q+4β^(2)(lql^(4)-1)q+4iβ(lql^(2))_(x)q=0,q(x,0)=q_(0)(x)-±1,x→±∞.The key to proving these results is to establish the formulation of a Riemann-Hilbert(RH)problem associated with the above Cauchy problem and find its connection with the RH problem of the defocusing NLS *** the■-steepest descent method and the results of the defocusing NLS equation,we find complete leading order approximation formulas for the defocusing KE equation on the whole(x,t)half-plane including soliton resolution and asymptotic stability of N-soliton solutions in a solitonic region,Zakharov-Shabat asymptotics in a solitonless region and the Painlevéasymptotics in two transition regions.

关键词： defocusing Kundu-Eckhaus equation Riemann-Hilbert problems steepest descent method soliton resolution asymptotic stability Painleve transcendents

Combination of diketone and PAO to achieve macroscale oil-based superlubricity at relative high contact pressures

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Friction 2024年第5期12卷 869-883页

作者： Shaonan DU Chenhui zhang zhi LUO State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing100084China Beijing National Laboratory of Molecular Sciences CAS Key Laboratory of Engineering PlasticsInstitute of ChemistryChinese Academy of SciencesBeijing100190China

1-(4-ethylphenyl)-nonane-1,3-dione(0206)is an oil-soluble liquid molecule with rod-like *** this study,the chelate(0206-Fe)with octahedral structure was prepared by the reaction of ferric chloride and 1,*** experimental results show that when using 0206 and a mixed solution containing 60%0206-Fe and 40%0206(0206-Fe(60%))as lubricants of the steel friction pairs,superlubricity can be achieved(0.007,0.006).But their wear scar diameters(WSD)were very large(532µm,370µm),which resulted in the pressure of only 44.3 and 61.8 MPa in the contact areas of the friction *** 0206-Fe(60%)was mixed with PAO6,it was found that the friction coefficient(COF)decreased with increase of 0206-Fe(60%)in the *** the ratio of 0206-Fe(60%)to PAO6 was 8:2(PAO6(20%)),it exhibited better comprehensive tribological properties(232.3 MPa).Subsequent studies have shown that reducing the viscosity of the base oil in the mixed solution helped to reduce COF and increased *** the COF,contact pressure,and running-in time,it was found that the mixed lubricant(Oil3(20%))prepared by the base oil with a viscosity of 19.7 mPa·s(Oil3)and 0206-Fe(60%)exhibited the best tribological properties(0.007,161.4 MPa,3,100 s).

关键词： diketone oil-based lubricants chelate superlubricity

The multiple roles of crop structural change in productivity,nutrition and environment in China:A decomposition analysis

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Journal of Integrative Agriculture 2024年第5期23卷 1763-1773页

作者： Xiangyang zhang Yumei zhang Shenggen fan College of Economics and Management China Agricultural UniversityBejing 100083China Academy of Global Food Economics and Policy China Agricultural UniversityBejing 100083China

China's crop structure has undergone significant changes in the last two decades since 2000,with an increase in the share of cereals,vegetables,and fruit,squeezing out other *** a result,land productivity,nutrient supply,and carbon emissions have *** to reallocate limited farmland among crops to achieve the multiple goals of agrifood systems becomes an important *** study explores the sources of land productivity and nutrition supply growth and carbon emissions reduction,and identifies the multiple roles of crop structural change from 2003 to 2020 based on a decomposition *** results reveal that the growth within crops is still the primary driver in land productivity and nutrition supply and the reduction in carbon ***,structural change also plays various roles at different *** 2003 to 2010,crop structural change increased the total calorie supply but lowered land productivity and contributed at least 70%of the total growth of carbon *** crop structure was relatively stable,and their effects were modest from 2010 to *** 2015 to 2020,the crop structural change began to play a greater role and generate synergistic effects in improving land productivity,micronutrient supply,and reducing carbon emissions,contributing to approximately a quarter of the growth of land productivity and 30%of total carbon emissions *** results suggest that strategies for crop structural change should comprehensively consider its multiple impacts,aiming to achieve co-benefits while minimizing trade-offs.

关键词： crop structural change land productivity nutrition carbon emissions