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IEEE International Conference on Plasma Science (ICOPS)

作者： X. Wang D. Xiao Institute of Applied Physics and Computational Mathematics Beijing China

ISBN: (数字)9798350360912

ISBN: (纸本)9798350360929

One of the applications of the Z-pinch technique is dynamic hohlraum driven inertial confinement fusion (ICF). This dynamic hohlraum is created by accelerating high-Z plasma to impact low-Z material through the magnetic field generated by pulse current. The interface between the high-Z plasma and the magnetic field is susceptible to Magneto-Rayleigh-Taylor (MRT) instability, which can lower the performance of the dynamic hohlraum. Understanding the relationship between the MRT instability and the rise time of the pulse current is crucial for achieving ignition in Z-pinch ICF. Initially, the scaling of MRT instability with the current rise time was investigated using theoretical and numerical methods. The study revealed that the perturbation amplitude of the instability increases linearly with the current rise time for the same implosion velocity when the Z-pinch constant coefficient is kept. To validate this finding, three types of wire-array experiments were conducted with similar implosion dynamics and nearly identical implosion velocities on an 8 MA pulse power generator. It is for the first time to achieve similar wire-array Z-pinch implosions while scaling up the current rise time to three times on the generator. The experimental outcomes, which included the shape of x-ray radiation and x-ray images of imploding plasmas, along with corresponding numerical analysis, confirmed that the MRT instability before stagnation indeed increases linearly with the rise time, consistent with the predictions of the theoretical model.

关键词： Shape Magnetic resonance imaging Magnetic confinement Perturbation methods Predictive models Generators Plasmas

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Streamline Tracing Visualization Of Flow On Surfaces 17

Streamline Tracing Visualization Of Flow On Surfaces

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17th International Conference on Interfaces and Human Computer Interaction 2023, IHCI 2023, the 17th International Conference on Computer Graphics, Visualization, Computer Vision and Image Processing 2023, CGVCVIP 2023 and 16th International Conference on Game and Entertainment Technologies 2023, GET 2023

作者： Wu, Fukun Cao, Yi Dong, Qingli CAEP Software Center for High Performance Numerical Simulation Beijing China Institute of Applied Physics and Computational Mathematics Beijing China

ISBN: (纸本)9789898704498

To address the visualization problem of surface streamline on complex curved surfaces, we present and implement an efficient surface streamline generation method for visualizing vector field on arbitrary geometry. The intersection calculation on curved surfaces with complex topology is performed to achieve the high-precision underlying vector. Then, this approach adopts an extended Runge-Kutta streamline integration technology for performing streamline tracing on an unstructured mesh, where the adaptive stepsize strategy and intersection acceleration structure are presented for sake of simplicity and efficiency. Finally, this approach is integrated into a visualization software to enhance the visualizing capability. The experimental results demonstrate that our approach can efficiently and accurately generate continuous and consistent geometric surface streamlines on curved surfaces. © 2023 Proceedings of the International Conferences on Interfaces and Human Computer Interaction 2023, IHCI 2023;Computer Graphics, Visualization, Computer Vision and Image Processing 2023, CGVCVIP 2023;and Game and Entertainment Technologies 2023, GET 2023. All rights reserved.

关键词： Computer games

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Massively parallel numerical simulation of 3D shock wave propagation based on JASMIN framework 3

Massively parallel numerical simulation of 3D shock wave pro...

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3rd International Conference on Defence Technology, ICDT 2022

作者： Liu, N. Zhang, P. Li, K. Yu, Y.Q. CAEP Software Center for High Performance Numerical Simulation Beijing China Institute of Applied Physics and Computational Mathematics Beijing China

An efficient massively parallel computing program for shock wave propagation named Shock3d is developed for shock wave damage mechanism in complex scenes. With the finite volume method, the program is built upon JASMIN (J parallel Adaptive Structured Mesh applications INfrastructure) and employs a component-based hierarchical organization structure. Using the patch-based core algorithm, Shock3d enables high parallel efficiency and strong parallel scalability with a parallel domain decomposition method and an image domain-based communication mode. It not only considers gravity, real gas effects, and boundaries in complex scenes, but also supports dynamic load balancing (DLB) and three-dimensional structured meshes and allows the parallel solution of hundreds of millions of mesh problems. Typical examples were used to verify the validity, parallelism, and high-resolution simulation results of the program developed. In the scalability test, where the propagation of shock waves through hundreds of millions of mesh elements was simulated on 300,000 CPU cores, the program delivered parallel efficiency of 60.84%. © Published under licence by IOP Publishing Ltd.

关键词： Shock waves

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norm convergence of IMEX BDF2 scheme with variable-step for the incompressible Navier-Stokes equations

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Numerical Algorithms 2024年第4期98卷 1917-1942页

作者： Ji, Bingquan Zhao, Xuan Institute of Applied Physics and Computational Mathematics Beijing China School of Mathematics Southeast University Nanjing China

We present an $$L^2$$ norm convergence of the implicit-explicit BDF2 scheme with variable-step for the unsteady incompressible Navier-Stokes equations with an inf-sup stable FEM for the space discretization. Under a w...

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Htem: High-Throughput Toolkit for Elasticity Modeling

SSRN

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SSRN 2025年

作者： Yang, Zhen Xian, Jiawei Xu, Yuanji Lin, De-Ye Wang, Qingchun Gao, Xingyu Tian, Fuyang Song, Haifeng Institute for Applied Physics University of Science and Technology Beijing Beijing100083 China National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing100094 China CAEP Software Center for High Performance Numerical Simulation Institute of Applied Physics and Computational Mathematics Beijing100094 China

The elasticity under varying temperatures and pressures is particularly significant for understanding mechanical properties and structural phase transitions. Consequently, there is an increasing demand for tools capable of determining elasticity across wide temperature and pressure ranges, either numerically or analytically. We propose HTEM, a comprehensive toolkit that automates the workflow for input generation, elastic calculations, modeling, and visualization within an integrated framework. HTEM performs simulations with four computational modes, allowing users to balance accuracy and efficiency. It incorporates a semi-analytic model for robust, high-precision elastic modeling with finite data combinations, even using sparse elasticity at high temperatures. To validate the workflows of calculation and modeling, we perform HTEM to study the elasticity of Si across wide temperature and pressure ranges. Results show the high precision and high efficiency of HTEM. And modeling mitigates noise from constant pressure ensemble simulations. Furthermore, HTEM provides detailed visualizations of elasticity and its anisotropy as functions of temperature and pressure, providing comprehensive insights into how the intrinsic properties of materials evolve under varying conditions. © 2025, The Authors. All rights reserved.

关键词： Elasticity

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A Positive-Preserving Unified Gas-Kinetic Scheme for Radiative Transfer Equations in Cylindrical Coordinates

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SSRN 2025年

作者： Wang, Yi Tan, Shuang Ni, Guoxi Wang, Yanli Institute of Applied Physics and Computational Mathematics China Beijing Computational Science Research Center China

The radiative transfer equations (RTEs) are important in the study of inertial confinement fusion (ICF). Cylindrical configurations are commonly employed in ICF studies, such as at the National Ignition Facility. Therefore we focus on numerical schemes for RTEs in cylindrical coordinates. Based on the unified gas-kinetic scheme (UGKS), a positive-preserving and asymptotic-preserving scheme is proposed. First, the kinetic equation in RTEs is decomposed into the rotation part and the transport-absorption part using a splitting strategy. The rotation part is solved using the positive-preserving semi-Lagrangian method. The positive-preserving scheme for the transport-absorption part is derived by establishing the equivalence between the time evolution solver and the update formula. Compared to previous studies, our scheme enables arbitrarily high-order reconstruction in both spatial and velocity spaces while preserving the positive-preserving property. Additionally, the asymptotic-preserving property is proven. Various numerical experiments confirm the high-order accuracy, positive-preserving property, and asymptotic-preserving property of our scheme. © 2025, The Authors. All rights reserved.

关键词： Radiative transfer

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Leveraging the Tensor Train Format for Many Energy Groups Deterministic Neutron Transport

Leveraging the Tensor Train Format for Many Energy Groups De...

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2024 International Conference on physics of Reactors, PHYSOR 2024

作者： Ortega, Mario I. Truong, Duc P. Computational Physics and Methods CCS-2 Los Alamos National Laboratory Los AlamosNM United States Applied Mathematics and Plasma Physics T-5 Los Alamos National Laboratory Los AlamosNM United States

ISBN: (纸本)9780894487972

The Tensor Train (TT) approach for the numerical solution of the discretized Boltzmann neutron transport equation (NTE) has shown great promise due to its low-rank approximation of the absorption/leakage, scattering, and fission o perators.T he t ensor t rain a pproach i s p art o f a larger set of tensor network techniques that use low-rank approximations to provide ultra-fast solutions of high-dimensional partial differential equations by breaking the curse of d *** of the NTE leads to large systems of linear equation that are in most cases difficult to ***, matrix-free methods are used to solve the discretized *** TT representation of the matrix operators makes storage and manipulation of these equations *** this work, we present a proof of concept application of tensor trains to the NTE for large number of energy *** demonstrate how the TT approach can be used with large numbers of energy groups to solve the NTE with a fine e nergy d iscretization t hat i s u sually i ntractable i n m ost c *** consider neutron cross section multigroup libraries up to 1236 groups and discuss the possibility of a semi-continuous-in-energy NTE *** show the storage costs of the discretized transport operators and solution *** also show results for time to solution for a one-dimensional slab problem using MATLAB on an Apple M2 Max, 64 GB RAM, MacBook Pro using the TT format and its linear algebra *** these sorts of many energy groups discretized neutron transport problems would be intractable on a laptop with MATLAB. © 2024 AMERICAN NUCLEAR SOCIETY. All rights reserved.

关键词： Tensors

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Measurement of 2p-3d absorption in a hot molybdenum plasma

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Matter and Radiation at Extremes 2024年第4期9卷 68-79页

作者： Gang Xiong Bo Qing Zhiyu Zhang Longfei Jing Yang Zhao Minxi Wei Yimeng Yang Lifei Hou Chengwu Huang Tuo Zhu Tianming Song Min Lv Yan Zhao Yuxue Zhang Guohong Yang Zeqing Wu Jun Yan Yaming Zou Jiyan Zhang Jiamin Yang Shanghai EBIT Laboratory and Key Laboratory of Nuclear Physics and Ion-Beam Application(MOE)Institute of ModernPhysicsFudan UniversityShanghai 200433China Laser Fusion Research Center China Academy of Engineering PhysicsMianyang 621900China Institute of Applied Physics and Computational Mathematics Beijing 100088China

We present measurements of the 2p-3d transition opacity of a hot molybdenum-scandium sample with nearly half-vacant molybdenum M-shell configurations.A plastic-tamped molybdenum-scandium foil sample is radiatively heated to high temperature in a compact D-shaped gold Hohlraum driven by∼30 kJ laser energy at the SG-100 kJ laser facility.X rays transmitted through the molybdenum and scandium plasmas are diffracted by crystals and finally recorded by image *** electron temperatures in the sample in particular spatial and temporal zones are determined by the K-shell absorption of the scandium plasma.A combination of the IRAD3D view factor code and the MULTI hydrodynamic code is used to simulate the spatial distribution and temporal behavior of the sample temperature and *** inferred temperature in the molybdenum plasma reaches a average of 138±11 eV.A detailed configuration-accounting calculation of the n=2–3 transition absorption of the molybdenum plasma is compared with experimental measurements and quite good agreement is *** present measurements provide an opportunity to test opacity models for complicated M-shell configurations.

关键词： molybdenum absorption configuration

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Approximating reproduction numbers: a general numerical method for age-structured models

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Mathematical Biosciences and Engineering 2024年第4期21卷 5360-5393页

作者： De Reggi, Simone Scarabel, Francesca Vermiglio, Rossana Department of Mathematics Computer Science and Physics University of Udine via delle Scienze 206 Udine33100 Italy Department of Applied Mathematics University of Leeds Woodhouse LeedsLS2 9JT United Kingdom CDLab – Computational Dynamics Laboratory University of Udine Italy

In this paper, we introduce a general numerical method to approximate the reproduction numbers of a large class of multi-group, age-structured, population models with a finite age span. To provide complete flexibility in the definition of the birth and transition processes, we propose an equivalent formulation for the age-integrated state within the extended space framework. Then, we discretize the birth and transition operators via pseudospectral collocation. We discuss applications to epidemic models with continuous and piecewise continuous rates, with different interpretations of the age variable (e.g., demographic age, infection age and disease age) and the transmission terms (e.g., horizontal and vertical transmission). The tests illustrate that the method can compute different reproduction numbers, including the basic and type reproduction numbers as special cases. c 2024 the Author(s), licensee AIMS Press.

关键词： Numerical methods

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Competition among the two-plasmon decay of backscattered light,filamentation of the electron-plasma wave and side stimulated Raman scattering

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High Power Laser Science and Engineering 2023年第6期11卷 87-94页

作者： K.Q.Pan Z.C.Li L.Guo T.Gong S.W.Li D.Yang C.Y.Zheng B.H.Zhang X.T.He Laser Fusion Research Center China Academy of Engineering PhysicsMianyangChina Center for Applied Physics and Technology Peking UniversityBeijingChina Institute of Applied Physics and Computational Mathematics BeijingChina

Competition among the two-plasmon decay(TPD)of backscattered light of stimulated Raman scattering(SRS),filamentation of the electron-plasma wave(EPW)and forward side SRS is investigated by two-dimensional particlein-cell *** previous work[*** et al.,*** 58,096035(2018)]showed that in a plasma with the density near 1/10 of the critical density,the backscattered light would excite the TPD,which results in suppression of the backward ***,this work further shows that when the laser intensity is so high(>10^(16)W/cm^(2))that the backward SRS cannot be totally suppressed,filamentation of the EPW and forward side SRS will be *** the TPD of the backscattered light only occurs in the early stage and is suppressed in the latter *** distribution functions further show that trapped-particle-modulation instability should be responsible for filamentation of the *** research can promote the understanding of hot-electron generation and SRS saturation in inertial confinement fusion experiments.

关键词： laser plasma instability inertial confinement fusion high energy density physics particle-in-cell simulation super-hot electrons

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