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Development of a Three-Dimensional Multiscale Octree SBFEM for Viscoelastic Problems of Heterogeneous Materials

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1831-1861页

作者： xu xu Xiaoteng Wang Haitian Yang Zhenjun Yang Yiqian He State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentDepartment of Engineering MechanicsDalian University of TechnologyDalian116024China Hubei Key Laboratory of Geotechnical and Structural Safety School of Civil EngineeringWuhan UniversityWuhan430072China Mechanik–Materialtheorie Ruhr-Universität BochumBochum44801Germany

The multiscale method provides an effective approach for the numerical analysis of heterogeneous viscoelastic materials by reducing the degree of freedoms(DOFs).A basic framework of the Multiscale Scaled Boundary Finite Element Method(MsSBFEM)was presented in our previous works,but those works only addressed two-dimensional *** order to solve more realistic problems,a three-dimensional MsSBFEM is further developed in this *** the proposed method,the octree SBFEM is used to deal with the three-dimensional calculation for numerical base functions to bridge small and large scales,the three-dimensional image-based analysis can be conveniently conducted in small-scale and coarse nodes can be flexibly adjusted to improve the computational ***,the Temporally Piecewise Adaptive Algorithm(TPAA)is used to maintain the computational accuracy of multiscale analysis by adaptive calculation in time *** results of numerical examples show that the proposed method can significantly reduce the DOFs for three-dimensional viscoelastic analysis with good *** instance,the DOFs can be reduced by 9021 times compared with Direct Numerical Simulation(DNS)with an average error of 1.87%in the third example,and it is very effective in dealing with three-dimensional complex microstructures directly based on images without any geometric modelling process.

关键词： Three-dimensionalmultiscale viscoelastic analysis numerical base functions octree SBFEM image-based analysis temporally piecewise adaptive algorithm

Optimal design for rubber concrete layered periodic foundations based on the analytical approximations of band gaps and mapping relations

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Earthquake Engineering and Engineering Vibration 2024年第3期23卷 593-608页

作者： Wu Qiaoyun xu Zhifeng xu Peishan Zeng Wenxuan Chen xuyong School of Civil Engineering and Architecture Wuhan Institute of TechnologyWuhan 430073China State Key Laboratory for Health and Safety of Bridge Structures Wuhan 430034China Wuhan Urban Construction Group Co. Ltd.Wuhan 430022China

The seismic performance of rubber concrete-layered periodic foundations are significantly influenced by their design,in which the band gaps play a paramount *** at providing better designs for these foundations,this study first proposes and validates the analytical formulas to approximate the bounds of the first few band *** addition,the mapping relations linking the frequencies of different band gaps are ***,an optimal design method for these foundations is developed,which is validated through an engineering *** is demonstrated that ensuring the superstructure’s resonance zones are completely covered by the corresponding periodic foundation’s band gaps can achieve satisfactory vibration attenuation effects,which is a good strategy for the design of rubber concrete layered periodic foundations.

关键词： periodic foundation band gap vibration attenuation seismic isolation optimal design

Metasurface-based computational imaging:a review

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Advanced Photonics 2024年第1期6卷 43-63页

作者： xuemei Hu Weizhu xu Qingbin Fan Tao Yue Feng Yan Yanqing Lu Ting xu Nanjing University Collaborative Innovation Center of Advanced MicrostructuresNational Laboratory of Solid-State MicrostructuresNanjingChina Nanjing University School of Electronic Sciences and EngineeringNanjingChina Nanjing University College of Engineering and Applied SciencesJiangsu Key Laboratory of Artificial Functional MaterialsNanjingChina

Metasurface-based imaging has attracted considerable attention owing to its compactness,multifunctionality,and subwavelength coding *** the integration of computational imaging techniques,researchers have actively explored the extended capabilities of metasurfaces,enabling a wide range of imaging *** present an overview of the recent progress in metasurface-based imaging techniques,focusing on the perspective of computational ***,we categorize and review existing metasurface-based imaging into three main groups,including(i)conventional metasurface design employing canonical methods,(ii)computation introduced independently in either the imaging process or postprocessing,and(iii)an end-to-end computation-optimized imaging system based upon *** highlight the advantages and challenges associated with each computational metasurface-based imaging technique and discuss the potential and future prospects of the computational boosted metaimager.

关键词： metasurface computational imaging inverse problem algorithm

Twisted Integration of Complex Oxide Magnetoelectric Heterostructures via Water‑Etching and Transfer Process

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Nano-Micro Letters 2024年第1期16卷 360-369页

作者： Guannan Yang Guohua Dong Butong Zhang xu xu Yanan Zhao Zhongqiang Hu Ming Liu State Key Laboratory for Manufacturing Systems Engineering Electronic Materials Research LaboratoryKey Laboratory of the Ministry of EducationEngineering Research Center of Spin Quantum Sensor ChipsUniversities of Shaanxi ProvinceSchool of Electronic Science and EngineeringXi’an Jiaotong UniversityXi’an 710049People’s Republic of China

Manipulating strain mode and degree that can be applied to epitaxial complex oxide thin films have been a cornerstone of strain *** recent years,lift-off and transfer technology of the epitaxial oxide thin films have been developed that enabled the integration of heterostructures without the limitation of material types and crystal ***,twisted integration would provide a more interesting strategy in artificial magnetoelectric heterostructures.A specific twist angle between the ferroelectric and ferromagnetic oxide layers corresponds to the distinct strain regulation modes in the magnetoelectric coupling process,which could provide some insight in to the physical *** this work,the La_(0.67)Sr_(0.33)MnO_(3)(001)/0.7Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.3PbTiO_(3)(011)(LSMO/PMN-PT)heterostructures with *** *** angles were assembled via water-etching and transfer *** transferred LSMO films exhibit a fourfold magnetic anisotropy with easy axis along LSMO.A coexistence of uniaxial and fourfold magnetic anisotropy with LSMO[110]easy axis is observed for the 45°Sample by applying a 7.2 kV cm^(−1)electrical field,significantly different from a uniaxial anisotropy with LSMO[100]easy axis for the 0°*** fitting of the ferromagnetic resonance field reveals that the strain coupling generated by the 45°twist angle causes different lattice distortion of LSMO,thereby enhancing both the fourfold and uniaxial *** work confirms the twisting degrees of freedom for magnetoelectric coupling and opens opportunities for fabricating artificial magnetoelectric heterostructures.

关键词： Magnetoelectric heterostructures Twist angle Epitaxial lift-off Magnetic anisotropy Ferromagnetic resonance

Designing gradient nanograined dual-phase structure in duplex stainless steel for superior strength-ductility synergy

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Journal of Materials Science & Technology 2024年第3期170卷 122-128页

作者： Songsong xu Ying Han Jiapeng Sun Guoqing Zu Mingkun Jiang Weiwei Zhu xu Ran Key Laboratory of Advanced Structural Materials Ministry of EducationChangchun University of TechnologyChangchun 130012China School of Materials Science and Engineering Changchun University of TechnologyChangchun 130012China Provincial Key Laboratory of Advanced Materials Processing and Application for Rail Transit Changchun University of TechnologyChangchun 130012China College of Mechanics and Materials Hohai UniversityNanjing 211100China

Similar to other metallic materials,duplex stainless steel dramatically loses its advantage of high ductility as they are ***,we produce a gradient nanograined dual-phase structure in the 2101 duplex stainless steel,thus facilitating a superior strength-ductility synergy:a yield strength of 1009.5 MPa being two times higher than that of the as-received sample,a total elongation of 23.4%and a uniform elongation of 5.9%.This novel structure is produced through a processing route of ultrasonic severe surface rolling and annealing,which realizes a superposition of gradient nanostructure and lamellar dual-phase structure with austenite and *** the tension deformation of gradi-ent nanograined dual-phase structured duplex stainless steel,a significant accumulation of geometrically necessary dislocations *** dislocations are formed to accommodate the deformation incompat-ibility caused by the layer-by-layer difference in strength and hardness of individual phase domains,as well as the inherent difference in properties between the austenite and ferrite *** results in a stronger hetero-deformation induced strengthening and hardening significantly contributing to superior mechanical *** study provides a new avenue to develop advanced steels with high strength and ductility.

关键词： Gradient structure Duplex stainless steel Synergetic strengthening Strength Ductility

Rolling Decision Model of Thermal Power Retrofit and Generation Expansion Planning Considering Carbon Emissions and Power Balance Risk

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Energy Engineering 2024年第5期121卷 1309-1328页

作者： Dong Pan xu Gui Jiayin xu Yuming Shen Haoran xu Yinghao Ma Economic and Technology Research Institute State Grid Anhui Electric Power Co.Ltd.Hefei230022China School of Electrical and Automation Engineering Hefei University of TechnologyHefei230009China

With the increasing urgency of the carbon emission reduction task,the generation expansion planning process needs to add carbon emission risk constraints,in addition to considering the level of power ***,methods for quantifying and assessing carbon emissions and operational risks are *** results in excessive carbon emissions and frequent load-shedding on some days,although meeting annual carbon emission reduction ***,in response to the above problems,carbon emission and power balance risk assessment indicators and assessment methods,were proposed to quantify electricity abundance and carbon emission risk level of power planning scenarios,considering power supply regulation and renewable energy fluctuation ***,building on traditional two-tier models for low-carbon power planning,including investment decisions and operational simulations,considering carbon emissions and power balance risks in lower-tier operational simulations,a two-tier rolling model for thermal power retrofit and generation expansion planning was *** model includes an investment tier and operation assessment tier and makes year-by-year decisions on the number of thermal power units to be retrofitted and the type and capacity of units to be ***,the rationality and validity of the model were verified through an example analysis,a small-scale power supply system in a certain region is taken as an *** model can significantly reduce the number of days of carbon emissions risk and ensure that the power balance risk is within the safe limit.

关键词： Carbon emission risk power balance risk thermal power retrofit generation expansion planning

High-speed penetration of ogive-nose projectiles into thick concrete targets:Tests and a projectile nose evolution model

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Defence Technology（防务技术） 2024年第2期32卷 553-571页

作者： xu Li Yan Liu Junbo Yan Zhenqing Shi Hongfu Wang Yingliang xu Fenglei Huang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China Beijing Institute of Technology Chongqing Innovation Center Chongqing401120China China Research and Development Academy of Machinery Equipment Beijing100089China

The majority of the projectiles used in the hypersonic penetration study are solid flat-nosed cylindrical projectiles with a diameter of less than 20 *** study aims to fill the gap in the experimental and analytical study of the evolution of the nose shape of larger hollow projectiles under hypersonic *** the hypersonic penetration test,eight ogive-nose AerMet100 steel projectiles with a diameter of 40 mm were launched to hit concrete targets with impact velocities that ranged from 1351 to 1877 m/*** erosion of the projectiles was observed during high-speed penetration of heterogeneous targets,and apparent localized mushrooming occurred in the front nose of recovered *** examining the damage to projectiles,a linear relationship was found between the relative length reduction rate and the initial kinetic energy of projectiles in different penetration ***,microscopic analysis revealed the forming mechanism of the localized mushrooming phenomenon for eroding penetration,i.e.,material spall erosion abrasion mechanism,material flow and redistribution abrasion mechanism and localized radial upsetting deformation ***,a model of highspeed penetration that included erosion was established on the basis of a model of the evolution of the projectile nose that considers radial upsetting;the model was validated by test data from the literature and the present *** upon the impact velocity,v0,the projectile nose may behave as undistorted,radially distorted or *** to the effects of abrasion of the projectile and enhancement of radial upsetting on the duration and amplitude of the secondary rising segment in the pulse shape of projectile deceleration,the predicted DOP had an upper limit.

关键词： High-speed penetration Concrete target Erosion Projectile nose evolution model

Bayesian inference of neutron-skin thickness and neutron-star observables based on effective nuclear interactions

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Science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 97-105页

作者： Jia Zhou Jun xu Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China School of Physics Science and Engineering Tongji UniversityShanghai 200092China

We have obtained the constraints on the density dependence of the symmetry energy from neutron-skin thickness data by parityviolating electron scatterings and neutron-star observables using a Bayesian approach,based on the standard Skyrme-HartreeFock(SHF)model and its extension as well as the relativistic mean-field(RMF)*** the neutron-skin thickness data(neutron-star observables)mostly constrain the symmetry energy at subsaturation(suprasaturation)densities,they may more or less constrain the behavior of the symmetry energy at suprasaturation(subsaturation)densities,depending on the energy-density functional *** showing the final posterior density dependence of the symmetry energy,we also compare the slope parameters of the symmetry energy at 0.10 fm-3as well as the values of the symmetry energy at twice saturation density from three effective nuclear *** present work serves as a comparison study based on relativistic and non-relativistic energy-density functionals,for constraining the nuclear symmetry energy from low to high densities using a Bayesian approach.

关键词： symmetry energy neutron skin neutron star

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Model-free method for LQ mean-field social control problems with one-dimensional state space

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Control Theory and Technology 2024年第3期22卷 479-486页

作者： Zhenhui xu Tielong Shen School of Engineering Tokyo Institute of TechnologyTokyo 152-8550Japan Department of Engineering and Applied Sciences Sophia UniversityTokyo 102-8554Japan

This paper presents a novel model-free method to solve linear quadratic(LQ)mean-field control problems with one-dimensional state space and multiplicative *** focus is on the infinite horizon LQ setting,where the conditions for solution either stabilization or optimization can be formulated as two algebraic Riccati equations(AREs).The proposed approach leverages the integral reinforcement learning technique to iteratively solve the drift-coefficient-dependent stochastic ARE(SARE)and other indefinite ARE,without requiring knowledge of the system dynamics.A numerical example is given to demonstrate the effectiveness of the proposed algorithm.

关键词： Mean-field control Social optima Infinite horizon Reinforcement learning