检索结果-内蒙古大学图书馆

arXiv 2024年

作者： Yu, Ziang Zhang, Shiwei Khoo, Yuehaw Committee on Computational and Applied Mathematics University of Chicago United States Center for Computational Quantum Physics Flatiron Institute United States Department of Statistics University of Chicago United States

We propose a novel algorithm for calculating the ground-state energy of quantum many-body systems by combining auxiliary-field quantum Monte Carlo (AFQMC) with tensor-train sketching. In AFQMC, a good trial wavefunction to guide the random walk is crucial for improving the sampling efficiency and controlling the sign problem. Our proposed method iterates between determining a new trial wavefunction in the form of a tensor train, derived from the current walkers, and using this updated trial wavefunction to anchor the next phase of AFQMC. Numerical results demonstrate that the algorithm is highly accurate for large spin systems. The overlap between the estimated trial wavefunction and the ground-state wavefunction also achieves high fidelity. We additionally provide a convergence analysis, highlighting how an effective trial wavefunction can reduce the variance in the AFQMC energy estimation. From a complementary perspective, our algorithm also extends the reach of tensor-train methods for studying quantum many-body *** Codes 15A69, 62G07, 65C05 Copyright © 2024, The Authors. All rights reserved.

关键词： Monte Carlo methods

来源：评论

学校读者我要写书评

暂无评论

Doping effects on the stacking fault energies of the γ' phase in Ni-based superalloys

引用

Chinese physics B 2020年第2期29卷 390-395页

作者： Weijie Li Chongyu Wang Department of Physics Tsinghua UniversityBeijing 100084China Institute of Applied Physics and Computational Mathematics Beijing 100088China

The doping effects on the stacking fault energies(SFEs),including the superlattice intrinsic stacking fault and superlattice extrinsic stacking fault,were studied by first principles calculation of the/phase in the Ni-based *** formation energy results show that the main alloying elements in Ni-based superalloys,such as Re,Cr,Mo,Ta,and W,prefer to occupy the Al-site in Ni3 AI,Co shows a weak tendency to occupy the Ni-site,and Ru shows a weak tendency to occupy the *** SFE results show that Co and Ru could decrease the SFEs when added to fault planes,while other main elements increase *** double-packed superlattice intrinsic stacking fault energies are lower than superlattice extrinsic stacking fault energies when elements(except Co) occupy an ***,the SFEs show a symmetrical distribution with the location of the elements in the ternary model.A detailed electronic structure analysis of the Ru effects shows that SFEs correlated with not only the symmetry reduction of the charge accumulation but also the changes in structural energy.

关键词： stacking fault energy site preference Ni-based superalloys electronic structure

来源：评论

学校读者我要写书评

暂无评论

Transition of the generation mechanism of high-order harmonics in an extended neon system

引用

Matter and Radiation at Extremes 2022年第4期7卷 21-29页

作者： Jingli Gao Difa Ye Jie Liu Wei Kang HEDPS Center for Applied Physics and Technology and College of EngineeringPeking UniversityBeijing 100871China Institute of Applied Physics and Computational Mathematics Beijing 100088China Graduate School China Academy of Engineering PhysicsBeijing 100193China

Using a time-dependent density functional theory method,we perform a systematic numerical study of the transition of high-order harmonic generation in neon(Ne)systems from an isolated Ne atom to an extended Ne system of solid *** show that ionized electrons wander in such extended systems until they meet a nearby ion and collide with *** maximum energy edge for the main feature of the high-order harmonic spectrum in this“wandering electron”picture is determined as Eedge=Ip+8Up,where Ip is the ionization energy of Ne and Up is the ponderomotive energy delivered by the driving *** factor of 8 comes from the maximum kinetic energy of an ionized electron in the driving laser *** the atomic limit of high-order harmonic spectra,a multiplatform feature is observed,corresponding to re-collisions of ionized electrons with their nearby *** is also shown that a Ne simple cubic lattice of appropriate size provides a selection condition for the direction of polarization of high-order harmonics beyond the atomic limit,which may be further used to manipulate the emitted radiation.

关键词： density. field. harmonics

来源：评论

学校读者我要写书评

暂无评论

Elastic scattering and total reaction cross sections of 6Li studied with a microscopic continuum discretized coupled channels model

arXiv

引用

arXiv 2023年

作者： Chen, Wendi Pang, D.Y. Guo, Hairui Ye, Tao Sun, Weili Ying, Yangjun School of Physics Beihang University Beijing100191 China Institute of Applied Physics and Computational Mathematics Beijing100094 China

We present a systematic study of 6Li elastic scattering and total reaction cross sections at incident energies around the Coulomb barrier within the continuum discretized coupled-channels (CDCC) framework, where 6Li is treated in an α+d two-body model. Collisions with 27Al, 64Zn, 138Ba and 208Pa are analyzed. The microscopic optical potentials (MOP) based on Skyrme nucleon-nucleon interaction for α and d are adopted in CDCC calculations and satisfactory agreement with the experimental data is obtained without any adjustment on MOPs. For comparison, the α and d global phenomenological optical potentials (GOP) are also used in CDCC analysis and a reduction no less than 50% on the surface imaginary part of deuteron GOP is required for describing the data. In all cases, the 6Li breakup effect is significant and provides repulsive correction to the folding model potential. The reduction on the surface imaginary part of GOP of deuteron reveals a strong suppression of the reaction probability of deuteron as a component of 6Li as compared with that of a free deuteron. A further investigation is made by taking the d breakup process into account equivalently within the dynamic polarization potential approach and it shows that d behaves like a tightly bound nucleus in 6Li induced reactions. Copyright © 2023, The Authors. All rights reserved.

关键词： Elastic scattering

来源：评论

学校读者我要写书评

暂无评论

Ergodicity for the fractional Magneto-Hydrodynamic equations driven by a degenerate pure jump noise

arXiv

引用

arXiv 2025年

作者： Wang, Xue Huang, Jianhua Zhang, Jiangwei College of Science National University of Defense Technology Changsha410073 China Institute of Applied Physics and Computational Mathematics Beijing100088 China

This paper is concerned with the ergodicity for stochastic 2D fractional magneto-hydrodynamic equations on the two-dimensional torus driven by a highly degenerate pure jump Lévy noise. We focus on the challenging case where the noise acts in as few as four directions, establishing new results for such high degeneracy. We first employ Malliavin calculus and anticipative stochastic calculus to demonstrate the equi-continuity of the semigroup (or so-called the e-property), and then verify the weak irreducibility of the solution process. Therefore, the uniqueness of invariant measure is proven. Copyright © 2025, The Authors. All rights reserved.

关键词： Differentiation (calculus)

来源：评论

学校读者我要写书评

暂无评论

Nonlocal effects on the shock-augmented ignition scheme of laser inertial fusion

引用

Physical Review Research 2024年第1期6卷 013332-013332页

作者： W. Q. Yuan Z. H. Zhao S. P. Zhu X. T. He B. Qiao Center for Applied Physics and Technology HEDPS and SKLNPT School of Physics Peking University Beijing 100871 China Institute of Applied Physics and Computational Mathematics Beijing 100094 China Frontiers Science Center for Nano-optoelectronics Peking University Beijing 100094 China

Shock-augmented ignition (SAI) has recently been proposed as a viable approach to optimize the shock ignition scheme of laser fusion, which may substantially reduce laser power and intensity requirements and, as a result, greatly inhibit the growth of laser-plasma instabilities. However, the nonlocal thermal transport effect, which is believed to play a significant role in shock ignition, has not been considered in evaluation of the SAI scheme yet. Here, by self-consistently including modeling of the space-time-dependent nonlocal thermal transport into the radiation hydrodynamic simulations, we revisit the whole implosion and ignition dynamics of SAI numerically and theoretically. We find that, due to the nonlocal effect, on the one hand, the time-delay window between the igniter spike and the compression pulse in the drive laser for achieving high-gain fusion is much broadened from about 0.45 to 0.7 ns, relaxing the difficulty of laser pulse shaping; on the other hand, both the coast time and the fusion burn duration are significantly reduced by, respectively, 0.22 ns and 47 ps, in favor of increasing the hot-spot pressure around the stagnation stage.

关键词： Direct drive High-energy-density plasmas Inertial confinement fusion Plasma fusion Plasma transport

来源：评论

学校读者我要写书评

暂无评论

Machine learning the Kondo entanglement cloud from local measurements

引用

Physical Review B 2024年第19期109卷 195125-195125页

作者： Faluke Aikebaier Teemu Ojanen Jose L. Lado Department of Applied Physics Aalto University 00076 Espoo Finland Computational Physics Laboratory Physics Unit Faculty of Engineering and Natural Sciences Tampere University FI-33014 Tampere Finland Helsinki Institute of Physics P.O. Box 64 FI-00014 Finland

A quantum coherent screening cloud around a magnetic impurity in metallic systems is the hallmark of the antiferromagnetic Kondo effect. Despite the central role of the Kondo effect in quantum materials, the structure of quantum correlations of the screening cloud has defied direct observations. In this work, we introduce a machine-learning algorithm that allows one to spatially map the entangled electronic modes in the vicinity of the impurity site from experimentally accessible data. We demonstrate that local correlators allow reconstruction of the local many-body correlation entropy in real space in a double Kondo system with overlapping entanglement clouds. Our machine-learning methodology allows bypassing the typical requirement of measuring long-range nonlocal correlators with conventional methods. We show that our machine-learning algorithm is transferable between different Kondo system sizes, and we show its robustness in the presence of noisy correlators. Our work establishes the potential machine-learning methods to map many-body entanglement from real-space measurements.

关键词： Entanglement detection Entanglement measures Kondo effect 1-dimensional systems Density matrix methods Machine learning Many-body techniques

来源：评论

学校读者我要写书评

暂无评论

Rapid Path Extraction and Three-Dimensional Roaming of the Virtual Endonasal Endoscope

引用

Chinese Journal of Electronics 2021年第3期30卷 397-405页

作者： WANG Yudong HAN Jing PAN Junjun WANG Jing CAO Yi ZHU Li LUO Yanlin School of Artificial Intelligence Beijing Normal University State Key Laboratory of Virtual Reality Technology and Systems Beihang University Institute of Applied Physics and Computational Mathematics Department of Otolaryngology Head and Neck Surgery Peking University Third Hospital

Compared with traditional endonasal endoscope, Virtual endonasal endoscope(VEE) is a computerized alternative solution with the advantages of being non-invasive, affordable, no perforation, low risk of infection, and high degree of sensitivity. A Central path extraction algorithm based on Pre-planning of the roaming area(CPE-PRA) is proposed to extract the central path of the nasal cavity model efficiently. And a B-spline curve fitting algorithm based on Relative center deviation(RCD)is introduced to fit a smooth curve to the extracted path,so that the virtual camera could have both a steady turning speed and a broad vision. A series of comparison tests were conducted to evaluate the effectiveness and efficiency of the proposed algorithms.

关键词： virtual instrumentation Virtual endonasal endoscope RCD rapid path extraction nasal cavity model medical image processing VEE feature extraction path planning CPE-PRA splines (mathematics) B-spline curve fitting algorithm computerized alternative solution roaming area relative center deviation virtual camera Central path extraction algorithm curve fitting endoscopes surgery medical robotics three-dimensional roaming

来源：评论

学校读者我要写书评

暂无评论

Global Well-Posedness and Stability of Classical Solutions to The Pressureless Navier-Stokes System in 3d

SSRN

引用

SSRN 2024年

作者： Guo, Boling Tang, Houzhi Zhao, Bin Institute of Applied Physics and Computational Mathematics Beijing100088 China Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China

In this paper, we consider the Cauchy problem of the pressureless Navier-Stokes system which can be derived by taking the high Mach number limit for compressible Navier-Stokes equations. Due to the absence of pressure, the classical perturbation theory developed by Matsumura and Nishida ([J. Math. Kyoto Univ., 20(1):67-104, 1980]) is not applicable to this model. The major difficulty lies in lack of the uniform boundedness of density. To solve this problem, we employ the spectral analysis and energy method to obtain the L2 time-decay rates of velocity under the additional assumption that the initial velocity is small in the L1 norm. Then combining the time-decay rates of velocity yields the uniform boundedness of density. Furthermore, it is proved that the velocity of pressureless flow decays to the motionless state at an optimal time-decay rate of (1 + t)−3/4 in the L2-norm. © 2024, The Authors. All rights reserved.

关键词： Spectrum analysis

来源：评论

学校读者我要写书评

暂无评论

Comparison of Simulation and Measurements of Time-Domain Field-to-Line Coupling in Bounded wave Simulator

Comparison of Simulation and Measurements of Time-Domain Fie...

引用

2022 International applied computational Electromagnetics Society Symposium, ACES-China 2022

作者： Zhong, Longquan Lin, Jiangchuan Qin, Feng Yang, Chun Liu, Chang Huang, Hua Complicated Electromagnetic Environment Laboratory of Caep Institute of Applied Electronics Mianyang China Software Center for High Performance Numerical Simulation of Caep Institute of Applied Physics and Computational Mathematics Beijing China Science and Technology on High Power Microwave Laboratory Institute of Applied Electronics Mianyang China

ISBN: (纸本)9781665452366

This paper presents an analysis of time-domain electromagnetic pulse coupling to single wire. A field-to-line coupling model was established. The simulation is performed using the uniform plane wave excitation defined by measured high-altitude nuclear electromagnetic pulse (HEMP) field signal, the induced currents of two load terminals are simulated. The validation measurement of single wire above the grounding plate is conducted in the bounded wave simulator. The frequency response of the actual coupled current signal monitoring system is considered in the data preprocessing. The comparison between simulation and measurement results show that the peak amplitude and waveform can coincide well. © 2022 IEEE.

关键词： Electromagnetic simulation

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：