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Phase-field simulations of the effect of temperature and interface for zirconiumδ-hydrides

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Chinese Physics B 2024年第4期33卷 701-710页

作者：陈子航盛杰刘瑜施小明黄厚兵许可王越超武帅孙博刘海风宋海峰 School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Advanced Research institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijing 100088China department of Physics University of Science and Technology BeijingBeijing 100083China

Hydride precipitation in zirconium cladding materials can damage their integrity and *** temperature and material defects have a significant effect on the dynamic growth of *** this study,we have developed a phasefield model based on the assumption of elastic behaviour within a specific temperature range(613 K-653 K).This model allows us to study the influence of temperature and interfacial effects on the morphology,stress,and average growth rate of zirconium *** results suggest that changes in temperature and interfacial energy influence the length-to-thickness ratio and average growth rate of the hydride *** ultimate determinant of hydride orientation is the loss of interfacial coherency,primarily induced by interfacial dislocation defects and quantifiable by the mismatch degree *** escalation in interfacial coherency loss leads to a transition of hydride growth from horizontal to vertical,accompanied by the onset of redirection ***,redirection occurs at a critical mismatch level,denoted as qc,and remains unaffected by variations in temperature and interfacial ***,this redirection leads to an increase in the maximum stress,which may influence the direction of hydride crack *** research highlights the importance of interfacial coherency and provides valuable insights into the morphology and growth kinetics of hydrides in zirconium alloys.

关键词： zirconium hydride phase-field method temperature effect mismatch degree

A new quantity in Finsler geometry

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Science China mathematics 2024年第4期67卷 883-890页

作者： Xiaohuan Mo Xiaoyang Wang Key Laboratory of Pure and applied mathematics School of Mathematical SciencesPeking UniversityBeijing 100871China School of mathematics and Statistics Beijing Institute of TechnologyBeijing 100081China

In this paper,we study a new Finslerian quantity■defined by the T-curvature and the angular metric *** show that the■-curvature not only gives a measure of the failure of a Finsler metric to be of scalar flag curvature but also has a vanishing *** find that the■-curvature is closely related to the Riemann curvature,the Matsumoto torsion and theΘ-*** solve ***’s open problem in terms of the■-***,we give a global rigidity result for Finsler metrics of negative Ricci curvature on a compact manifold via the■-curvature,generalizing a theorem previously only known in the case of negatively curved Finsler metrics of scalar flag curvature.

关键词： Finsler metric Finslerian quantity T-curvature -curvature Randers metric

Deformation and mutual influence of two cylindrical water columns in tandem subjected to shock wave

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Chinese Physics B 2024年第8期33卷 316-327页

作者：洪振宇宋洋王睿马宗强马东军王裴 institute of applied Physics and Computational mathematics Beijing 100094China Graduate School of China Academy of Engineering Physics Beijing 100088China Center for applied Physics and technology Peking UniversityBeijing 100871China

The interaction between shock waves and multiple cylinders,referred to as shock–cylinder interaction(SCI),is an important phenomenon in science and ***,its underlying physical mechanisms remain *** study entailed the numerical simulation of the aerobreakup of two tandem water columns subjected to a high-speed gas flow by using an adaptive mesh refinement(AMR)-based diffusion-interface *** objective was to elucidate the changes in water–column deformation patterns over a wide range of Weber *** analysis was performed to examine the deformation of the water columns in vertical *** reveal distinct deformation patterns between the two columns as the Weber number ***,an extended exponential stretching law model was devised,and its improved capability to predict the deformation patterns was demonstrated.

关键词： shock-cylinder interaction(SCI) Weber number effect aerobreakup multiphase flow

A Composite Ansatz for Calculation of Dynamical Structure Factor

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Chinese Physics Letters 2024年第1期41卷 92-103页

作者：张玉佩莫崇杰张平康炜 HEDPS Center for Applied Physics and Technologyand School of PhysicsPeking UniversityBeijing 100871China beijing Computational Science Research Center Beijing 100193China institute of applied Physics and Computational mathematics Beijing 100088China HEDPS Center for Applied Physics and Technologyand College of EngineeringPeking UniversityBeijing 100871China

We propose an ansatz without adjustable parameters for the calculation of a dynamical structure *** ansatz combines the quasi-particle Green’s function,especially the contribution from the renormalization factor,and the exchange-correlation kernel from time-dependent density functional theory together,verified for typical metals and semiconductors from a plasmon excitation regime to the Compton scattering *** has the capability to reconcile both small-angle and large-angle inelastic x-ray scattering(IXS)signals with muchimproved accuracy,which can be used as the theoretical base model,in inversely inferring electronic structures of condensed matter from IXS experimental signals *** may also be used to diagnose thermal parameters,such as temperature and density,of dense plasmas in x-ray Thomson scattering experiments.

关键词： excitation inverse verified

Ionization Potential Depression Model for Warm/Hot and Dense Plasmas

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Chinese Physics Letters 2024年第8期41卷 45-57页

作者： Chensheng Wu Fuyang Zhou Jun Yan Xiang Gao Yong Wu Chunhua Zeng Jianguo Wang institute of applied Physics and Computational mathematics Beijing 100088China Faculty of Science Kunming University of Science and TechnologyKunming 650500China

For warm/hot and dense plasmas(WDPs),ionization potential depression(IPD)plays a crucial role in determining its ionization balance and understanding the resultant microscopic plasma properties.A sophisticated and unified IPD model is necessary to resolve those existing discrepancies between theoretical and experimental ***,the applicability of those widely used IPD models nowadays is limited,especially for the nonlocal thermodynamic equilibrium(non-LTE)dense plasma produced by short-pulse *** this work,we propose an IPD model that considers inelastic atomic processes,in which three-body recombination and collision ionization processes are found to play a crucial role in determining the electron distribution and IPD for a *** IPD model is validated by reproducing latest experimental results of Al plasmas with a wide-range condition of 70 eV–700 eV temperature and 0.2–3 times solid density,as well as a typical non-LTE system of hollow Al *** is demonstrated that the present IPD model has a significant temperature dependence due to the consideration of the inelastic collision *** a lower computational cost and wider application range of plasma conditions,the proposed model is expected to provide a promising tool to study the ionization balance and the atomic processes,as well as the related radiation and particle transports properties of the WDP.

关键词： properties. collision determining

Stability of the Phase Separation State for Compressible Navier-Stokes/Allen-Cahn System

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 45-74页

作者： Ya-zhou Chen Hakho Hong Xiao-ding Shi department of mathematics College of Mathematics and PhysicsBeijing University of Chemical TechnologyBeijing100029China institute of mathematics State Academy of SciencesPyongyangKorea

This paper is concerned with the large time behavior of the Cauchy problem for Navier-Stokes/AllenCahn system describing the interface motion of immiscible two-phase flow in 3-D. The existence and uniqueness of global solutions and the stability of the phase separation state are proved under the small initial perturbations. Moreover, the optimal time decay rates are obtained for higher-order spatial derivatives of density,velocity and phase. Our results imply that if the immiscible two-phase flow is initially located near the phase separation state, then under small perturbation conditions, the solution exists globally and decays algebraically to the complete separation state of the two-phase flow, that is, there will be no interface fracture, vacuum, shock wave, mass concentration at any time, and the interface thickness tends to zero as the time t → +∞.

关键词： Navier-Stokes/Allen-Cahn system existence uniqueness large time behavior decay rate

Digital signal acquisition system for complex nuclear reaction experiments

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Nuclear Science and Techniques 2024年第1期35卷 124-133页

作者： Wei-Liang Pu Yan-Lin Ye Jian-Ling Lou Jia-Hao Chen School of Physics and State Key Laboratory of Nuclear Physics and technology Peking UniversityBeijing 100871China institute of applied Physics and Computational mathematics Beijing 100094China

A digital data-acquisition system based on XIA LLC products was used in a complex nuclear reaction experiment using radioactive ion beams.A flexible trigger system based on a field-programmable gate array(FPGA)parametrization was developed to adapt to different experimental sizes.A user-friendly interface was implemented,which allows converting script language expressions into FPGA internal control *** proposed digital system can be combined with a conventional analog data acquisition system to provide more *** performance of the combined system was veri-fied using experimental data.

关键词： Digital signal acquisition system Trigger Programmable logic Timestamp

Crashworthiness Design and Multi-Objective Optimization of Bionic Thin-Walled Hybrid Tube Structures

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Computer Modeling in Engineering & Sciences 2024年第4期139卷 999-1016页

作者： Pingfan Li Jiumei Xiao department of applied Mechanics University of Sciences and Technology BeijingBeijing100083China

Thin-walled structures are widely used in cars due to their lightweight construction and energy-absorbing ***,issues such as high initial stress and lowenergy-absorbing efficiency *** study proposes a novel energy-absorbing structure inwhich a straight tube is combinedwith a conical tube and a bamboo-inspired bulkhead structure is *** configuration allows the conical tube to flip outward first and then fold together with the straight *** deformation mode absorbs more energy and less peak force than the conical tube sinking and flipping *** finite element numerical simulation,the specific energy absorption capacity of the structure is increased by 26%compared to that of a regular circular cross-section ***,the impact resistance of the bionic straight tapered tube structure is further improved through multi-objective optimization,promoting the engineering application and lightweight design of hybrid cross-section tubes.

关键词： Crashworthiness tube inversion multi-objective optimization energy absorption

Scaling laws governing the elastic properties of 3D graphenes

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Science China(Technological Sciences) 2024年第6期67卷 1748-1756页

作者： LI Ming LU Guo YU HaoDong LI MengLei ZHENG FaWei Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement(MOE)School of PhysicsBeijing Institute of TechnologyBeijing100081China beijing Key Lab of Nanophotonics&Ultrafine Optoelectronic Systems School of PhysicsBeijing Institute of TechnologyBeijing100081China Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijing100088China department of Physics Capital Normal UniversityBeijing100048China

In this study,we comprehensively investigated the scaling law for elastic properties of three-dimensional honeycomb-like graphenes(3D graphenes)using hybrid neural network potential-based molecular dynamics simulations and theoretical *** elastic constants were obtained as functions of honeycomb hole size,denoted by the graphene wall length *** five independent elastic constants in the large-L limit are proportional to L^(-1).The associated coefficients are combinations of elastic constants of two-dimensional ***-order terms including L^(-2)and L^(-3)emerge for finite L *** have three origins,the distorted areas close to the joint lines of 3D graphenes,the variation in solid angles between graphene plates,and the bending distortion of graphene ***,the chirality becomes essential with decreasing L because the joint line structures are different between the armchair and zigzag-type 3D *** findings provide insights into the elastic properties of graphene-based superstructures and can be used for further studies on graphene-based materials.

关键词： scaling law neural network elastic properties 3D graphene