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Coherent enhancement of a frequency comb modulated by a terahertz laser field in high-order harmonic generation

Physical Review A 2023年第4期108卷 043101-043101页

作者： Yuan-Yuan Wu Chang-Tong Liang Bao-Guang Zhao Peng-Cheng Li Research Center for Advanced Optics and Photoelectronics Department of Physics College of Science Shantou University Shantou Guangdong 515063 China Key Laboratory of Intelligent Manufacturing Technology of MOE Shantou University Shantou Guangdong 515063 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China

We present the coherent enhancement of the frequency comb via high-order harmonic generation (HHG) in a train of infrared laser pulses combined with terahertz (THz) laser fields. The HHG spectra are obtained by solving the three-dimensional time-dependent Schrödinger equation by means of the time-dependent generalized pseudospectral method. We find that the structure of the frequency comb via HHG becomes much smoother and more regular, and the yield of the comb is increased by nearly two orders of magnitude. By analyzing the phase coherence of HHG spectra, we demonstrate that the THz laser fields are responsible for the optimization of the structure and yield of the frequency comb since the constructive phase coherence of the HHG spectra is modulated by the THz field. The physical origin of the constructive phase coherence is thanks to the uniform ionization efficiency induced by the THz laser field for each laser pulse, which greatly improves the synchronization of the harmonic emission. Our finding provides a promising method for the enhancement of the frequency comb via HHG.

关键词： Atomic & molecular processes in external fields High-order harmonic generation Light-matter interaction Ultrafast phenomena

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TensorMD: Molecular Dynamics Simulation with Ab Initio Accuracy of 50 Billion Atoms 25

TensorMD: Molecular Dynamics Simulation with Ab Initio Accur...

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Proceedings of the 30th ACM SIGPLAN Annual Symposium on Principles and Practice of Parallel Programming

作者： Yucheng Ouyang Ying Liu Honghui Shang Zhenchuan Chen Jiahao Shan Huimin Cui Xiaobing Feng Xin Chen Xingyu Gao Lifang Wang Haifeng Song Rongfen Lin Fang Li Institute of Computing Technology Chinese Academy of Sciences Beijing China National Research Center of Parallel Computer Engineering and Technology Beijing China Institute of Applied Physics and Computational Mathematics Beijing China

ISBN: (纸本)9798400714436

Molecular dynamics simulation emerges as an important area that HPC+AI helps to investigate the physical properties, with machine-learning interatomic potentials (MLIPs) being used. General-purpose machine-learning (ML) tools have been leveraged in MLIPs, but they are not perfectly matched with each other, since many optimization opportunities in MLIPs have been missed by ML tools. This inefficiency arises from the fact that HPC+AI applications work with far more computational complexity compared with pure AI scenarios. This paper has developed an MLIP, named TensorMD, independently from any ML tool. TensorMD has been evaluated on two supercomputers and scaled to 51.8 billion atoms, i.e., ~ 3× compared with state-of-the-art.

关键词： GPU

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Detailed discussion of discrepancy between theoretical and observed spectral lines in Kr-like W38+ based on advanced consideration of core electron correlations

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Chinese physics B 2025年第5期 331-341页

作者：彭国庆王凯颜君康炜 Center for Applied Physics and Technology Peking University Department of Physics and Anhui Key Laboratory of Optoelectric Materials Science and Technology Key Laboratory of Functional Molecular Solids Ministry of Education Anhui Normal University Institute of Applied Physics and Computational Mathematics

For the observed line at 799.23 ? in tungsten EBIT experiment,which was as signed to be3F4~o-3F3~o（[Ar]4s24p54d） of W38+ion,there were noticeable deviations for most calculated wavelengths from the measured *** clarify this issue,we carry out an extensive calculation for energy levels and transition properties of W38+ion using the multi-configuration Dirac-Hartree-Fock and relativistic configuration interaction method,in which more deeper inner core electron correlations are included,and different forms of Breit interaction as well as quantum electrodynamics corrections are *** is found that the inner core electron correlations can affect the total energy of levels,while only slightly modify the excited energy of levels in 4s24p54d *** present calculated wavelengths agree with the corresponding measured values excellently except the line at 799.23 ?.Thus we are strongly suspicious this line should be misidentified,and suggest that new experiment with higher resolution and spectra analysis based on more accurate atomic data should be performed for W38+ion.

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ON BILINEAR STRICHARTZ ESTIMATES ON WAVEGUIDES WITH APPLICATIONS

arXiv

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arXiv 2024年

作者： Deng, Yangkendi Fan, Chenjie Yang, Kailong Zhao, Zehua Zheng, Jiqiang Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing China Academy of Mathematics and Systems Science Hua Loo-Keng Key Laboratory of Mathematics Chinese Academy of Sciences Beijing China Chongqing National Center for Applied Mathematics Chongqing Normal University Chongqing China Department of Mathematics and Statistics Beijing Institute of Technology Beijing China Key Laboratory of Algebraic Lie Theory and Analysis of Ministry of Education Beijing China Institute of Applied Physics and Computational Mathematics Beijing100088 China National Key Laboratory of Computational Physics Beijing100088 China

We study local-in-time and global-in-time bilinear Strichartz estimates for the Schrödinger equation on waveguides. As applications, we apply those estimates to study global well-posedness of nonlinear Schrö... 详细信息

关键词： Schrodinger equation

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Study of the atmospheric neutron radiation effects using compact laser-driven spallation neutron source

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Physical Review Research 2025年第1期7卷 013071-013071页

作者： Z. B. Wu Y. L. Yao X. F. Shen K. Li A. D. Liu X. T. He B. Qiao Center for Applied Physics and Technology HEDPS and SKLNPT School of Physics Peking University Beijing 100871 China Research Center of Laser Fusion China Academy of Engineering Physics (CAEP) Mianyang 621900 China Institute of System Engineering China Academy of Engineering Physics (CAEP) Mianyang 621900 China Institute of Applied Physics and Computational Mathematics Beijing 100094 China Frontiers Science Center for Nano-optoelectronic Peking University Beijing 100094 China

We propose a laboratory accelerated test method for study of the atmospheric neutron radiation effects by using a compact laser-driven spallation neutron source (LDSNS). The LDSNS is obtained by injecting a GeV quasimonoenergetic proton beam accelerated by light-sail (LS) radiation pressure of intense lasers into a lead target. According to the LS scaling law, proton energy spectra can be regulated by adjusting the laser and foil target parameters, so that the neutron spectra at various atmospheric altitudes are well reproduced. Integrated PIC and MC simulations have verified the scheme (for that at altitude 12 km, laser intensity of 1022W/cm2 is required) and shown that the neutron fluence per laser shot is as high as 1.73×108n/cm2, equivalent to 3.7 year flux accumulation in atmosphere. Using the G4SEE toolkit, we estimate that the HM628128 SRAM may undergo an average of ten single event upsets per shot for the proposed laboratory test.

关键词： Spalling

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Fundamentals of lax-Wendroff type approach to hyperbolic problems with discontinuities 6

Fundamentals of lax-Wendroff type approach to hyperbolic pro...

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6th ECCOMAS European Conference on computational Mechanics: Solids, Structures and Coupled Problems, ECCM 2018 and 7th ECCOMAS European Conference on computational Fluid Dynamics, ECFD 2018

作者： Li, Jiequan Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing China Center for Applied Physics and Technology Peking University Beijing China

ISBN: (纸本)9788494731167

This lecture presents the understanding of the fundamentals when designing a numerical schemes for hyperbolic problems with discontinuities as parts of their solutions. The fundamentals includes the consistency with hyperbolic balance laws in integral form rather than PDE form, spatial-temporal coupling, thermodynamic consistency for computing compressible fluid flows, convergence arguments and multidimensionality etc. . Some numerical results are shown to display the performance. copyright © Crown copyright (2018).All right reserved.

关键词： computational fluid dynamics

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Inverted pin beams for robust propagation through atmospheric turbulence

Inverted pin beams for robust propagation through atmospheri...

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CLEO: Science and Innovations in CLEO 2024, CLEO: S and I 2024 - Part of Conference on Lasers and Electro-Optics

作者： Droulias, Sotiris Loulakis, Michalis Papazoglou, Dimitris G. Tzortzakis, Stelios Chen, Zhigang Efremidis, Nikolaos K. Institute of Applied and Computational Mathematics Foundation for Research and Technology - Hellas Crete Heraklion70013 Greece Department of Digital Systems University of Piraeus Piraeus18534 Greece Institute of Electronic Structure and Laser Foundation for Research and Technology - Hellas P.O. Box 1527 Crete Heraklion71110 Greece Department of Materials Science and Technology University of Crete Crete Heraklion700 13 Greece MOE Key Laboratory of Weak-Light Nonlinear Photonics TEDA Applied Physics Institute School of Physics Nankai University Tianjin300457 China Collaborative Innovation Center of Extreme Optics Shanxi University Shanxi Taiyuan030006 China Department of Applied Mathematics University of Crete Heraklion71409 Greece

We introduce a new class of beams the "inverted pin beams". We show that in atmospheric turbulence inverted pin beams outperform (have reduced scintillations) other classes of beams in moderate to strong flu...

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Spatial second-order positive and asymptotic preserving unified gas kinetic schemes for radiative transfer equations

Spatial second-order positive and asymptotic preserving unif...

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第十二届全国流体力学学术会议

作者： Xiaojing Xu Song Jiang Wenjun Sun School of Mathematics and Physics Southwest University of Science and Technology Institute of Applied Physics and Computational Mathematics Center for Applied Physics and Technology College of Engineering Peking University

We propose two spatial second-order schemes for linear radiative transfer equations by using the idea of the unified gas kinetic scheme(UGKS) to construct the numerical boundary fluxes,and show that the proposed schemes are both positive and asymptotic preserving. The UGKS was proposed by Xu and Huang [29] for continuum and rarefied flows firstly, and was then applied to a linear radiative transfer equation by Mieussens in [20] where the asymptotic preserving property of UGKS is shown. Although it is asymptotic preserving, UGKS can not always keep the positivity of solutions. We first apply UGKS to discretize a linear radiative transfer equation to have a spatial second-order scheme. Then, by a detailed analysis of the numerical boundary fluxes, we are able to find the reasons why the positive preserving property of UGKS fails. Finally, we carefully employ a linear scaling limiter and a flux correction to make UGKS positive-preserving but still asymptotic-preserving. Consequently, we propose two spatial second-order positive and asymptotic preserving unified gas kinetic schemes for the linear radiative transfer equation, thus improving the earlier work [32] where only a first-order positive and asymptotic scheme is developed. The proposed schemes can well capture the solution of the diffusion limit equation in optically thick regions without requiring the cell size being smaller than the photon's mean free path, while the solution in optically thin regions can also be well resolved in a natural way. To our best knowledge,this is the first time that a spatial high-order(second-order) positive and asymptotic preserving gas kinetic scheme for linear radiative transfer equations is constructed. Several numerical experiments are included to validate the spatial second-order accuracy, positive-and asymptotic-preserving properties of the proposed schemes.

关键词： Radiative transfer equation unified gas kinetic scheme discrete ordinate method second-order scheme positive preserving asymptotic preserving

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Single- and double-electron capture in intermediate-energy Ar8+ + He collisions

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Physical Review A 2022年第4期106卷 042809-042809页

作者： Y. W. Zhang J. W. Gao Y. Wu J. G. Wang N. Sisourat A. Dubois Center for Applied Physics and Technology HEDPS and School of Physics Peking University Beijing 100871 China School of Physics Hangzhou Normal University Hangzhou 311121 China Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China Sorbonne Université CNRS UMR 7614 Laboratoire de Chimie Physique-Matière et Rayonnement 75005 Paris France

Single- and double-electron-capture processes occurring in Ar8+ and He collisions are investigated in a broad energy domain ranging from 0.1 to 100 keV/u. Total and partial cross sections are calculated using a two-active-electron semiclassical asymptotic-state close-coupling approach. For single-electron-capture cross sections the present results show the best overall agreement with available experimental data for both total and partial cross sections, and possible reasons for observed discrepancies are discussed. Furthermore, we extend the understanding of the electron-capture processes on that system to impact energies above 20 keV/u for which no data exist. The cross sections for double-electron-capture processes are also reported and show severe discrepancies with the rare available experimental data.

关键词： Atomic & molecular collisions Charge-transfer collisions

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Fracture Prediction for an Advanced High-Strength Steel Sheet Using the Fully Coupled Elastoplastic Damage Model with Stress-State Dependence

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Acta Mechanica Solida Sinica 2021年第2期34卷 263-273页

作者： Kai Zhang Mingchuan Wang Weijie Liu Jianlin Liu College of Pipeline and Civil Engineering China University of Petroleum(East China)Qingdao 266580China Sino-French Engineer School Nanjing University of Science and TechnologyNanjing 210094China Institute of Applied Physics and Computational Mathematics Beijing 10094China

In this study,the numerical simulations of sheet metal forming processes are performed based on a fully coupled elastoplastic damage *** effects of stress triaxiality and Lode angle are introduced into the damage evolution law to capture the loading-path-dependent *** proposed constitutive model is implemented into the finite element(FE)code ABAQUS/Explicit via the user-defined subroutine(VUMAT).Next,the identification procedure for DP780 based on the hybrid experimental-numerical method is presented in *** numerical results of simple tests are compared with the experiments,and obvious improvement is observed for the proposed model under various loading ***,the model is applied to predict the edge fracture during sheet blanking *** predicted global load–displacement responses and crack paths have a good agreement with the experimental results,indicating that the model holds great potentials in simulation of metal forming processes.

关键词： Ductile damage Full coupling Stress state Numerical simulation Edge fracture

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