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Numerical Simulation of Microstructure Formation and Forecast of Mechanical Properties for Spheroidal Graphite Iron

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Journal of Materials Science & Technology 2003年第Z1期19卷 13-16页

作者： Weimin ZHAO Shuping hou haipeng LI Aiwen HU School of Materials Science and Engineering Hebei University of TechnologyTianjin 300132 China Tianjin Commercial University 300400 China School of Materials Science and Engineering Hebei University of TechnologyTianjin 300132 China School of Materials Science and Engineering Hebei University of TechnologyTianjin 300132 China

The numerical simulation can overcome the hardship of mathematical analysis and experimental research, explicate the mechanism of microstructure shaping, predict mechanical properties and operating life of castings and then optimize technology and control microstructure formation to obtain the qualified castings. The finite difference method (FDM) is applied to the simulation of temperature field based on all kinds of nucleation and growth models on all stages of solidification of spheroidal graphite cast iron. Visual C++ is used to program the numerical simulation software, QTstructure-1 to simulate the solidification process of spheroidal graphite cast iron and the formation of all phases in solidification process. Finally, the result of simulation is well agreed with the experimental result.

关键词： Spheroidal graphite iron, Numerical simulation, Finite difference method, Temperature field

用于加速度传感器的气动活塞式冲击校准装置研究

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机械制造与自动化 2024年第4期53卷 87-92页

作者：陈志龙侯海鹏杨建罗仕挺王汝苗杨东方严豪杰杭州集普科技有限公司浙江杭州311106 浙江工业大学机械工程学院浙江杭州310032

基于比较校准法,研制了用于加速度传感器、包含机械冲击模块、冲击信号生成模块和测量控制模块的气动活塞式冲击校准装置。在关键参数分析计算和重要数学模型建立的基础上,对比不同种类波形发生器产生的冲击曲线结果,确定直径20 mm、厚... 详细信息

基于比较校准法,研制了用于加速度传感器、包含机械冲击模块、冲击信号生成模块和测量控制模块的气动活塞式冲击校准装置。在关键参数分析计算和重要数学模型建立的基础上,对比不同种类波形发生器产生的冲击曲线结果,确定直径20 mm、厚度5 mm的羊毛毡为优选的波形发生器,其冲击峰值幅度和脉冲持续时间的重复性均不超过3%,达到国外同类产品的技术水平。同时,相对扩展不确定度符合ISO 16063—22规定的小于5%(k=2)的要求。

关键词：加速度传感器气动活塞校准装置冲击峰值幅度脉冲持续时间不确定度

Permian integrative stratigraphy,biotas,paleogeographical and paleoclimatic evolution of the Qinghai-Tibetan Plateau and its surrounding areas

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Science China Earth Sciences 2024年第4期67卷 1107-1151页

作者： Shuzhong SHEN Yichun ZHANG Dongxun YUAN haipeng XU Qi JU Hua ZHANG Quanfeng ZHENG Mao LUO Zhangshuai hou State Key Laboratory for Mineral Deposits Research School of Earth Sciences and Engineering and Frontiers Science Center for Critical Earth Material CyclingNanjing UniversityNanjing 210023China State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and PalaeontologyChinese Academy of SciencesNanjing 210008China University of Chinese Academy of Sciences Nanjing 210049China School of Resources and Geosciences China University of Mining and TechnologyXuzhou 221116China

The Permian Period was a critical time interval during which various blocks of the Qinghai-Tibetan Plateau have experienced profound and complex paleogeographical *** supercontinent Pangea was formed to its maximum during this interval,hampering a global east-to-west trending equatorial warm ocean ***,a semi-closed Tethys Ocean warm pool formed an eastward-opening oceanic embayment of Pangea,and became an engine fostering the evolutions of organisms and environmental changes during the Paleozoic-Mesozoic *** and preserved fossil groups have proved extremely useful in understanding such changes and the evolutionary histories of the Qinghai-Tibetan *** distributed Permian deposits and fossils from various blocks of the Qinghai-Tibetan Plateau exhibited varied characteristics,reflecting these blocks’different paleolatitude settings and drifting *** Himalaya Tethys Zone south to the Yarlung Zangbo suture zone,located in the northern Gondwanan margin,yields fossil assemblages characterized by cold-water organisms throughout the Permian,and was affliated to those of the *** of the exotic limestone blocks within the Yarlung Zangbo suture zone are Guadalupian(Middle Permian)to Early Triassic in *** exotic limestone blocks bear fossil assemblages that have transitional affinities between the warm Tethys and cold Gondwanan regions,suggesting that they most probably represent seamount deposits in the Neo-Tethys *** the Asselian to Sakmarian(Cisuralian,also Early Permian),the Cimmerian microcontinents in the northern part of Gondwana preserved glacio-marine deposits of Asselian to Sakmarian,and contained typical Gondwana-type cold-water *** the middle Cisuralian(~290-280 Ma),the Cimmerian microcontinents rifted off from the Gondwanaland,and drifted northward allometrically due to the active magmatism of the Panjal Traps in the northern margin of the Indian *** slices of micro

关键词： Permian Tethys Ocean Qinghai-Tibetan Plateau Biotas Paleogeography

Preparation of Laser Cladding Coating Undercooling Cu-based Alloy and Co on Non-equilibrium Solidification Structure

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 463-472页

作者：田徐铭 CAO Shichao hou Kai hou Xiaopeng WANG Hongfu 张煜 Department of Outpatient Xinzhou People’s HospitalXinzhou 034099China School of Mechanical Engineering North University of ChinaTaiyuan 030051China Department of Neurosurgery Xinzhou People’s HospitalXinzhou 034099China Department of Orthopedics Xinzhou People’s HospitalXinzhou 034099China

The effect of the gradient content of Co element on the solidification process of Cu-based alloy under deep under cooling conditions was *** non-equilibrium solidification structure of the under cooled alloy samples were *** is found that the rapidly solidified alloy has undergone twice grain refinement during the undercooling *** and significance of the maximum undercooling refinement structure of Cu60Ni35Co5 at T=253 K were ***-density defects were observed,such as dislocations,stacking faults networks,and twinning *** standard FCC diffraction pattern represents that it is still a single-phase *** on the metallographic diagram,EBSD and TEM data analysis,it is illustrated that the occurrence of grain refinement under high undercooling is due to stress induced *** addition,the laser cladding technology is used to coat Co-based alloy(Stellite12) coating on 304 stainless steel substrate;the microstructure of the coating cross-section was *** was found that the microstructure of the cross-section is presented as columnar crystals,planar crystals,and disordered growth direction,so that the coating has better hardness and wear *** electrochemical corrosion of the substrate and coating,it can be seen that the Co and Cr elements present in the coating are more likely to form a dense passivation film,which improved the corrosion resistance of the coating.

关键词： non-equilibrium solidification structure undercooling recrystallization laser cladding coating

Integral Operators Between Fock Spaces

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Chinese Annals of Mathematics,Series B 2024年第2期45卷 265-278页

作者： Yongqing LIU Shengzhao hou School of Mathematics and Statistics Changshu Institute of TechnologySuzhou 215006JiangsuChina School of Mathematical Sciences Soochow UniversitySuzhou 215006JiangsuChina

In this paper,the authors study the integral operator■induced by a kernel functionφ(z,·)∈F_α~∞between Fock *** 1≤p≤∞,they prove that S_φ:F_α^(1)→F_α^(p)is bounded if and only if■where k_(a)is the normali... 详细信息

关键词： Fock spaces Integral operators Normalized reproducing kernel

In-Plane Dynamic Crushing Behaviors of a Vertex-Based Hierarchical Auxetic Honeycomb

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Acta Mechanica Solida Sinica 2024年第1期37卷 53-62页

作者： Yichen Zan Xiuhui hou Zichen Deng School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi'an 710072China MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical UniversityXi'an 710072China School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentDalian University of TechnologyDalian 116024China

Auxetic metamaterials,which exhibit the negative Poisson’s ratio(NPR)effect,have found wide applications in many engineering ***,their high porosity inevitably weakens their bearing capacity and impact *** improve the energy absorption efficiency of auxetic honeycombs,a novel vertex-based hierarchical star-shaped honeycomb(VSH)is designed by replacing each vertex in the classical star-shaped honeycomb(SSH)with a newly added self-similar *** analytical model is built to investigate the Young’s modulus of VSH,which shows good agreement with experimental results and numerical *** in-plane dynamic crushing behaviors of VSH at three different crushing velocities are investigated,and empirical formulas for the densification strain and plateau stress are *** results reveal more stable deformation modes for VSH,attributed to the addition of self-similar star-shaped ***,compared with SSH under the same relative densities,VSH exhibits better specific energy absorption and higher plateau ***,VSH is verified to be a better candidate for energy absorption while maintaining the auxetic *** study is expected to provide a new design strategy for auxetic honeycombs.

关键词： Vertex-based hierarchical star-shaped honeycomb Auxetic honeycomb Energy absorption Plateau stress Negative Poisson's ratio

An Improved Method for Approximating the Infinite-Horizon Value Function of the Discrete-Time Switched LQR Problem

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Journal of Systems Science & Complexity 2024年第1期37卷 22-39页

作者： hou Tan LI Yuanlong LIN Zongli Department of Automation Shanghai Jiao Tong UniversityShanghai 200240China Key Laboratory of System Control and Information Processing Ministry of Education of ChinaShanghai 200240China Shanghai Engineering Research Center of Intelligent Control and Management Shanghai 200240China Charles L.Brown Department of Electrical and Computer Engineering University of VirginiaCharlottesvilleVA 22904-4743USA

This paper considers the problem of approximating the infinite-horizon value function of the discrete-time switched LQR *** particular,the authors propose a new value iteration method to generate a sequence of monotonically decreasing functions that converges exponentially to the value *** method facilitates us to use coarse approximations resulting from faster but less accurate algorithms for further value iteration,and thus,the proposed approach is capable of achieving a better approximation for a given computation time compared with the existing *** numerical examples are presented in this paper to illustrate the effectiveness of the proposed method.

关键词： Optimal control switched linear systems switched LQR problem.

Theoretical study on the stability of nanobubbles and its verification in molecular dynamics simulation

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Particuology 2024年第4期87卷 99-105页

作者： Sheng Mi Chaofeng hou Wei Ge School of Chemical Engineering and Technology Tianjin UniversityTianjin300072China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing.100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing100049China

The stability of vapor nanobubbles in bulk liquid was investigated theoretically and the critical bubble size was derived from macroscale thermodynamic equations,below which the system destabilizes with sharp drop in *** critical size was quantitatively verified in molecular dynamic simulation using the Lennard-Jones model of argon,where stronger attraction between the molecules at lower density is found to contribute most to the drop of system pressure and,as the Laplace pressure on the curved bubble interface fails to balance the pressure difference across the interface,the bubbles become *** theoretical model could be extended to other systems where reliable equations of state and interfacial tension are available.

关键词： Nanobubble Stability Phase diagram Critical size

Tailored energy absorption for a novel auxetic honeycomb structure under large deformation

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Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 63-80页

作者： Xiuhui hou Bin Wang Zichen Deng School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi'an 710129China MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical UniversityXi'an 710072China School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentDalian University of TechnologyDalian 116024China

In comparison to conventional hexagonal honeycomb structures,auxetic metamaterials with re-entrant configurations have exhibited superior mechanical properties in terms of energy *** further enhance the energy absorption capacity of these materials,a novel re-entrant honeycomb configuration,named novel auxetic re-entrant honeycomb(NARH),is developed by incorporating“”-shaped cell walls into the conventional auxetic re-entrant honeycomb(ARH).Two analytical models for the plateau stress are formulated to consider the plastic deformation of NARH during quasi-static compression and the dynamic impact using the linear momentum ***-static compression tests on 3D printed NARH honeycomb specimens and finite element simulations are performed to verify the effectiveness of the theoretical *** exhibits higher plateau stresses compared with ARH during compression,which can be attributed to the presence of more plastic hinges formed in *** hinges,the embedded parts with inclined cell walls,not only improve stability by forming stable triangles during compression but also enhance the energy absorption capacity.A parametric study is conducted to analyze the effect of impact velocity,thickness,and incline angle of cell walls on *** simulations demonstrate higher sensitivity of the mechanical properties to impact velocity and cell wall *** ribs to the“”-shaped cell walls in NARH further reduces the initial peak force during dynamic crushing while maintaining high energy *** research provides valuable guidelines for the design of energy absorption metamaterials.

关键词： absorption walls shaped