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multiscale topology optimization using feature-driven method

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Chinese Journal of Aeronautics 2020年第2期33卷 621-633页

作者： Zhao XU Weihong ZHANG Ying ZHOU Jihong ZHU State IJR Center of Aerospace Design and Additive Manufacturing Northwestern Polytechnical UniversityXi’an 710072China

This paper presents a multiscale design method for simultaneous topology optimization of both macrostructures and *** features are extended as design primitives at both macro and micro scales and represented by Level Set Functions(LSFs).Parameters related to the locations,sizes,and orientations of macro and micro features are considered as design variables and optimized *** the overlapping areas of different macro features,embedded microstructures are optimally figured out as the solution of the corresponding sub-optimization,*** this study,the eXtended Finite Element Method(XFEM)is implemented for structural and sensitivity analyses with respect to design *** method has the advantage of using a fixed grid independent of the topology optimization *** homogenization procedure is applied to calculate the effective properties of considered microstructures in each macro *** examples are presented to illustrate the effectiveness of the proposed *** depict that the multiscale design cannot obviously improve structural stiffness compared with a solid-material design under the linear elastic condition.

关键词： Feature-driven method Level set function multiscale design Topology optimization XFEM

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multiscale eigenelement method for periodical composites: A review

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Chinese Journal of Aeronautics 2019年第1期32卷 104-113页

作者： Yufeng XING Yahe GAO Institute of Solid Mechanics Beihang University

Based on the eigenvector expansion idea, the multiscale Eigenelement Method(MEM)was proposed by the author and co-workers. MEM satisfies two equivalent conditions, one condition is the equivalence of strain energy, and the other is the deformation similarity. These two equivalent conditions character the structure-preserving property of a multiscale analysis method. The equivalence of strain energy is necessary for achieving accurate macro behaviors such as lower order frequencies, while the deformation similarity is essential for predicting accurate micro behaviors such as stresses. The MEM has become a powerful multiscale method for the analysis of composite structures because of its high accuracy and efficiency. In this paper, the research advances of MEM are reviewed and all types of eigenelement methods are compared, focusing on superiorities and deficiencies from practical viewpoint. It is concluded that the eigenelement methods with smooth shape functions are more suitable for the analysis of macro behaviors such as lower order frequencies, and the eigenelement methods with piecewise shape functions are suitable for the analysis of both macro and micro behaviors.

关键词： Composite Deformation similarity Eigenelement Energy equivalence Mechanical analysis multiscale

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multiscale mechanical modeling of hydrated cement paste under tensile load using the combined DEM-MD method

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Frontiers of Structural and Civil Engineering 2017年第3期11卷 270-278页

作者： Yue HOU Linbing WANG National Center for Materials Service Safety University of Science and Technology Beijing Beijing 100083 China Joint USTB-Virginia Tech Lab on Multifunctional Materials USTB Beijing Virginia Tech Blacksburg VA 24061 USA

In this paper, a combined DEM-MD method is proposed to simulate the crack failure process of Hydrated Cement Paste （HCP） under a tensile force. A three-dimensional （3D） multiscale mechanical model is established using the combined Discrete Element Method （DEM）-Molecular Dynamics （MD） method in LAMMPS （Large-scale Atomic/ Molecular Massively Parallel Simulator）. In the 3D model, HCP consists of discrete particles and atoms. Simulation results show that the combined DEM-MD model is computationally efficient with good accuracy in predicting tensile failures of HCP.

关键词： hydrated cement paste multiscale MD simulation DEM

multiscale Simulation of a Novel Leaf-vein-inspired Gradient Porous Wick Structure

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Journal of Bionic Engineering 2019年第5期16卷 828-841页

作者： Yuanqiang Luo Wangyu Liu Jingren Gou School of Mechanical and Automotive Engineering South China University of TechnologyGuangzhou 510641China

With the rapid development of photoelectric products,their miniaturization and high integration have intensified the problem of heat *** chamber is a special type of heat pipe that is a particularly effective heat spreader for *** this paper,a novel Leaf-vein-inspired Gradient Porous(LGP)wick structure is designed macroscopically and the LGP design is verified using a general *** that,the gradient porous design Model IGis selected for the subsequent mesoscopic *** a connected 2D random LGP wick model presenting porosity gradient is generated by the expanded quartet structure generation set *** the mesoscopic Lattice Boltzmann Method(LBM),the flow and heat transfer in the LGP wick model is *** verification,FLUENT based on the macroscopic finite volume method is used as a ***,the microscopic flow behaviors in the 2D random LGP wick model are analyzed using the LBM *** the entire flowing process from the inlet to outlet,it is possible to explain the mesoscopic and macroscopic phenomena well based on the microscopic flow behaviors.

关键词： vapor chamber leaf-vein-inspired gradient porous wick structure lattice Boltzmann method multiscale simulation bionic cooling

multiscale Simulation of Microstructure Evolution during Preparation and Service Processes of Physical Vapor Deposited c-TiAlN Coatings

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Computers, Materials & Continua 2024年第6期79卷 3435-3453页

作者： Yehao Long Jing Zhong Tongdi Zhang Li Chen Lijun Zhang State Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083China

Physical Vapor Deposited(PVD)TiAlN coatings are extensively utilized as protective layers for cutting tools,renowned for their excellent comprehensive *** optimize quality control of TiAlN coatings for cutting tools,a multi-scale simulation approach is proposed that encompasses the microstructure evolution of coatings considering the entire preparation and service lifecycle of PVD TiAlN *** scheme employs phase-field simulation to capture the essential microstructure of the PVD-prepared TiAlN ***,cutting simulation is used to determine the service temperature experienced during cutting processes at varying ***-Hilliard modeling is finally utilized to consume the microstructure and service condition data to acquaint the microstructure evolution of TiAlN coatings throughout the cutting *** methodology effectively establishes a correlation between service temperature and its impact on the microstructure evolution of TiAlN *** is expected that the present multi-scale numerical simulation approach will provide innovative strategies for assisting property design and lifespan prediction of TiAlN coatings.

关键词： multiscale phase-field TiAlN coatings PVD cutting

multiscale ApEn and SampEn in Quantifying Nonlinear Complexity of Depressed MEG

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Chinese Journal of Electronics 2019年第4期28卷 817-821页

作者： YAO Wenpo HU Hui WANG Jun YAN Wei LI Jin HOU Fengzhen School of Telecommunications and Information Engineering Nanjing University of Posts and Telecommunications School of Geography and Biological Information Nanjing University of Posts and Telecommunications Brain Hospital Affiliated to Nanjing Medical University College of Physics and Information Technology Shaanxi Normal University School of Science China Pharmaceutical University

Depression is a neurophysiological disorder with recurrent dysregulations of self-mental states. multiscale Approximate entropy(ApEn) and Sample entropy(SampEn) are employed to characterize nonlinear complexity of Magnetoencephalography(MEG) of depressive patients in our contribution. SampEn shares similarities with ApEn while has better distinctions between the MEGs of depression patients and normal people. Test results prove that nonlinear complexity of the depressive MEG is lower than that of the normal subjects, indicating weaker response of depression patients to emotional stimuli, and the optimum discriminations between the depressive and healthy people lie in frontal lobe of brain which is related to emotional regulation. Our findings provide valuable information about depression, highlight the loss of nonlinear complexity in MEG of depressive patient and can be used as clinical diagnostic aids.

关键词： Magnetoencephalography Depression Approximate entropy Sample entropy multiscale

multiscale carbon foam confining single iron atoms for efficient electrocatalytic CO2 reduction to CO

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Nano Research 2019年第9期12卷 2313-2317页

作者： Zheng Zhang Chao Ma Yunchuan Tu Rui Si Jie Wei Shuhong Zhang Zhen Wang Jian-Feng Li Ye Wang Dehui Deng State Key Laboratory of Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry far Energy Materials (iChEM)College oj Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China State Key Laboratory of Catalysis iChEMDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China College of Materials Science and Engineering Hunan UniversityChangsha 410082China Shanghai Synchrotron Radiation Facility Shanghai Institute of Applied PhysicsChinese Academy of SciencesShanghai 201204China Materials and Structural Analysis Division Thermo Fisher ScientificInternational BioislandGuangzhou 510320China

Electrocatalytic CO2 reduction to CO is a sustainable process for energy ***,this process is still hindered by the diffusi limited mass transfer,low electrical conductivity and catalytic ***,new strategies for catalyst design should be adopted to solve these problems and improve the electrocatalytic performa nee for CO ***,we report a multiscale carb on foam confining〔single iron atoms prepared with the assistant of S1O2 *** pore-enriched environment at the macro-scale facilitates the diffusion of reacta nts and *** graphe ne nano sheets at the nano-scale promote the charge tran sfer duri ng the *** single iron atoms con fined in carb on matrix at the atomic-scale provide the active sites for electrocatalytic CO2 reductio n to *** optimized catalyst achieves a CO Faradaic efficiency of 94.9%at a moderate potential of-0.5 V ***,the performance can be maintained over 60 hours due to the stable single iron atoms coordi nated with four n itroge n atoms in the carb on *** work provides a promising strategy to improve both the activity and stability of single atom catalysts for electrocatalytic CO2 reduction to CO.

关键词： CO2 reduction electrocatalysis multiscale structure carbon foam single iron atoms

multiscale HOMOGENIZATION OF NONLINEAR HYPERBOLIC EQUATIONS WITH SEVERAL TIME SCALES

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Acta Mathematica Scientia 2011年第3期31卷 843-856页

作者： Jean Louis Woukeng David Dongo Department of Mathematics and Computer Science Faculty of Science University of Dschang

We study the multiscale homogenization of a nonlinear hyperbolic equation in a periodic *** obtain an accurate homogenization *** also show that as the nonlinear term depends on the microscopic time variable,the global homogenized problem thus obtained is a system consisting of two hyperbolic *** is also shown that in spite of the presence of several time scales,the global homogenized problem is not a reiterated one.

关键词： hyperbolic multiscale nonlinear

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multiscale spatiotemporal meteorological drought prediction:A deep learning approach

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Advances in Climate Change Research 2024年第2期15卷 211-221页

作者： Jia-Li ZHANG Xiao-Meng HUANG Yu-Ze SUN Department of Earth System Science Ministry of Education Key Laboratory for Earth System ModellingInstitute for Global Change StudiesTsinghua UniversityBeijing 100084China

Reliable monitoring and thorough spatiotemporal prediction of meteorological drought are crucial for early warning and decision-making regarding drought-related *** utilisation of multiscale methods is effective for a comprehensive evaluation of drought occurrence and progression,given the complex nature of meteorological ***,the nonlinear spatiotemporal features of meteorological droughts,influenced by various climatological,physical and environmental factors,pose significant challenges to integrated prediction that considers multiple indicators and time *** address these constraints,we introduce an innovative deep learning framework based on the shifted window transformer,designed for executing spatiotemporal prediction of meteorological drought across multiple *** formulate four prediction indicators using the standardized precipitation index and the standard precipitation evaporation index as core methods for drought definition using the ERA5 reanalysis *** indicators span time scales of approximately 30 d and one ***-term indicators capture more anomalous variations,whereas long-term indicators attain comparatively higher accuracy in predicting future *** focus on the East Asian region,notable for its diverse climate conditions and intricate terrains,to validate the model's efficacy in addressing the complexities of nonlinear spatiotemporal *** model's performance is evaluated from diverse spatiotemporal viewpoints,and practical application values are analysed by representative drought *** results substantiate the effectiveness of our proposed model in providing accurate multiscale predictions and capturing the spatiotemporal evolution characteristics of *** of the four drought indicators accurately delineates specific facets of the meteorological drought ***,three representative drought events,namely flash drought,sustained drought and severe drought,

关键词： Meteorological drought Spatiotemporal prediction multiscale Swim transformer Deep learning