检索结果-内蒙古大学图书馆

arXiv 2023年

作者： Zhang, Duo Liu, Xinzijian Zhang, Xiangyu Zhang, Chengqian Cai, Chun Bi, Hangrui Du, Yiming Qin, Xuejian Peng, Anyang Huang, Jiameng Li, Bowen Shan, Yifan Zeng, Jinzhe Zhang, Yuzhi Liu, Siyuan Li, Yifan Chang, Junhan Wang, Xinyan Zhou, Shuo Liu, Jianchuan Luo, Xiaoshan Wang, Zhenyu Jiang, Wanrun Wu, Jing Yang, Yudi Yang, Jiyuan Yang, Manyi Gong, Fu-Qiang Zhang, Linshuang Shi, Mengchao Dai, Fu-Zhi York, Darrin M. Liu, Shi Zhu, Tong Zhong, Zhicheng Lv, Jian Cheng, Jun Jia, Weile Chen, Mohan Ke, Guolin Weinan, E. Zhang, Linfeng Wang, Han AI for Science Institute Beijing100080 China DP Technology Beijing100080 China Academy for Advanced Interdisciplinary Studies Peking University Beijing100871 China State Key Lab of Processors Institute of Computing Technology Chinese Academy of Sciences Beijing100871 China University of Chinese Academy of Sciences Beijing100871 China HEDPS CAPT College of Engineering Peking University Beijing100871 China Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo315201 China CAS Key Laboratory of Magnetic Materials and Devices Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology Chinese Academy of Sciences Ningbo315201 China School of Electronics Engineering and Computer Science Peking University Beijing100871 China Shanghai Engineering Research Center of Molecular Therapeutics & New Drug Development School of Chemistry and Molecular Engineering East China Normal University Shanghai200062 China Laboratory for Biomolecular Simulation Research Institute for Quantitative Biomedicine Department of Chemistry and Chemical Biology Rutgers University PiscatawayNJ08854 United States Department of Chemistry Princeton University PrincetonNJ08540 United States College of Chemistry and Molecular Engineering Peking University Beijing100871 China Yuanpei College Peking University Beijing100871 China School of Electrical Engineering and Electronic Information Xihua University Chengdu610039 China State Key Laboratory of Superhard Materials College of Physics Jilin University Changchun130012 China Key Laboratory of Material Simulation Methods & Software of Ministry of Education College of Physics Jilin University Changchun130012 China International Center of Future Science Jilin University Changchun130012 China Key Laboratory for Quantum Materials of Zhejiang Province Department of Physics School of Science Westlake University Zhejiang Hangzhou310030 China Atomistic Simulations Italia

The rapid advancements in artificial intelligence (AI) are catalyzing transformative changes in atomic modeling, simulation, and design. AI-driven potential energy models have demonstrated the capability to conduct large-scale, long-duration simulations with the accuracy of ab initio electronic structure methods. However, the model generation process remains a bottleneck for large-scale applications. We propose a shift towards a model-centric ecosystem, wherein a large atomic model (LAM), pre-trained across multiple disciplines, can be efficiently fine-tuned and distilled for various downstream tasks, thereby establishing a new framework for molecular modeling. In this study, we introduce the DPA-2 architecture as a prototype for LAMs. Pre-trained on a diverse array of chemical and materials systems using a multi-task approach, DPA-2 demonstrates superior generalization capabilities across multiple downstream tasks compared to the traditional single-task pre-training and fine-tuning methodologies. Our approach sets the stage for the development and broad application of LAMs in molecular and materials simulation research. Copyright © 2023, The Authors. All rights reserved.

关键词： Multi-task learning

来源：评论

学校读者我要写书评

暂无评论

Quantum Inspired Optimization for Industrial Scale Problems

arXiv

引用

arXiv 2023年

作者： Banner, William P. Hadiashar, Shima Bab Mazur, Grzegorz Menke, Tim Ziolkowski, Marcin Kennedy, Ken Romero, Jhonathan Cao, Yudong Grover, Jeffrey A. Oliver, William D. Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States Zapata Computing Inc. 100 Federal St 20th Floor BostonMA02110 United States Department of Computational Methods in Chemistry Jagiellonian University Gronostajowa 2 Kraków30-387 Poland Research Laboratory of Electronics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Harvard University CambridgeMA02138 United States BMW Group Information Technology Research Center 2 Research Dr. GreenvilleSC29607 United States

Model-based optimization, in concert with conventional black-box methods, can quickly solve large-scale combinatorial problems. Recently, quantum-inspired modeling schemes based on tensor networks have been developed which have the potential to better identify and represent correlations in datasets. Here, we use a quantum-inspired model-based optimization method TN-GEO to assess the efficacy of these quantum-inspired methods when applied to realistic problems. In this case, the problem of interest is the optimization of a realistic assembly line based on BMW's currently utilized manufacturing schedule. Through a comparison of optimization techniques, we found that quantum-inspired model-based optimization, when combined with conventional black-box methods, can find lower-cost solutions in certain contexts. Copyright © 2023, The Authors. All rights reserved.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Physics-based modeling and predictive simulation of powder bed fusion additive manufacturing across length scales

arXiv

引用

arXiv 2021年

作者： Meier, Christoph Fuchs, Sebastian L. Much, Nils Nitzler, Jonas Penny, Ryan W. Praegla, Patrick M. Pröll, Sebastian D. Sun, Yushen Weissbach, Reimar Schreter, Magdalena Hodge, Neil E. Hart, A. John Wall, Wolfgang A. Institute for Computational Mechanics Technical University of Munich Boltzmannstrasse 15 Garching Munich85748 Germany Institute for Continuum and Material Mechanics Hamburg University of Technology Hamburg Germany Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge United States Unit of Strength of Materials and Structural Analysis University of Innsbruck Innsbruck Austria Methods Development Group Lawrence Livermore National Laboratory Livermore United States

Powder bed fusion additive manufacturing (PBFAM) of metals has the potential to enable new paradigms of product design, manufacturing and supply chains while accelerating the realization of new technologies in the medical, aerospace, and other industries. Currently, wider adoption of PBFAM is held back by difficulty in part qualification, high production costs and low production rates, as extensive process tuning, post-processing, and inspection are required before a final part can be produced and deployed. Physics-based modeling and predictive simulation of PBFAM offers the potential to advance fundamental understanding of physical mechanisms that initiate process instabilities and cause defects. In turn, these insights can help link process and feedstock parameters with resulting part and material properties, thereby predicting optimal processing conditions and inspiring the development of improved processing hardware, strategies and materials. This work presents recent developments of our research team in the modeling of metal PBFAM processes spanning length scales, namely mesoscale powder modeling, mesoscale melt pool modeling, macroscale thermo-solid-mechanical modeling and microstructure modeling. Ongoing work in experimental validation of these models is also summarized. In conclusion, we discuss the interplay of these individual submodels within an integrated overall modeling approach, along with future research directions. Copyright © 2021, The Authors. All rights reserved.

关键词： 3D printers

来源：评论

学校读者我要写书评

暂无评论

Excess pressure and electric fields in nonideal plasma hydrodynamics

引用

Physical Review E 2019年第6期99卷 063207-063207页

作者： A. Diaw Michael S. Murillo Computational Physics and Methods Group Los Alamos National Laboratory Los Alamos New Mexico 87544 USA Department of Computational Mathematics Science and Engineering Michigan State University East Lansing Michigan 48824 USA

Nonideal plasmas have nontrivial space and time correlations, which simultaneously impact both the excess thermodynamic quantities as well as the collision processes. However, hydrodynamics models for designing and interpreting nonideal plasma experiments, such as inertial-confinement fusion experiments, typically neglect electrodynamics, although some models include electric fields indirectly through a generalized Fick's law. However, because most transport models are not computed self-consistently with the equation of state, there is double counting of the forces in the excess thermodynamic quantities and the collision terms. Here we employ the statistical mechanical hydrodynamic theory of Irving and Kirkwood [J. Chem. Phys. 18, 817 (1950)] to examine inhomogeneous, nonideal plasmas that contain electric fields. We show that it is not possible to simultaneously separate terms that correspond to electric fields and excess pressure; rather, these quantities arise from the same interparticle Coulomb forces. Moreover, new terms associated with nonlocality appear in the presence of strong inhomogeneities.

关键词： Aerodynamics Astrophysical fluid dynamics Hydrodynamic waves Inertial confinement fusion Hot dense plasma Hydrodynamic models

来源：评论

学校读者我要写书评

暂无评论

Heterogeneous multiscale method for high energy-density matter: Connecting kinetic theory and molecular dynamics

引用

Journal of computational Physics: X 2020年 8卷

作者： Shohet, Gil Price, Jacob Haack, Jeffrey Marciante, Mathieu Murillo, Michael S. Department of Aeronautics and Astronautics Stanford University StanfordCA94305 United States Department of Applied Mathematics University of Washington SeattleWA98195 United States Computational Physics and Methods Group Los Alamos National Laboratory Los AlamosNM87545 United States Department of Computational Mathematics Science and Engineering Michigan State University East LansingMI48824 United States

We have developed a concurrent heterogeneous multiscale method (HMM) framework with a microscale molecular dynamics (MD) model and a macroscale kinetic Vlasov-BGK model. The kinetic model is formulated such that BGK collision times are the closure data obtained from MD. Using the H-theorem, we develop the mathematical link between the MD and the kinetic model. We examine three relaxation processes, energy, momentum, and bump-on-tail, using full microscale MD simulations as a reference solution. We find that solutions computed with the HMM framework offer a significant computational reduction (14×−100×) compared with computing a full MD solution, with significant improvements in accuracy compared with a kinetic model using analytical collision times. © 2020 The Authors

关键词： Molecular dynamics

来源：评论

学校读者我要写书评

暂无评论

Linear-multifrequency-grey acceleration for thermal radiation transport in the presence of Compton scattering

Linear-multifrequency-grey acceleration for thermal radiatio...

引用

2019 International Conference on Mathematics and computational methods Applied to Nuclear Science and engineering, M and C 2019

作者： Till, A.T. Morel, J.E. Los Alamos National Laboratory CCS-2: Computational Physics and Methods Group P.O. Box 1663 Los AlamosNM United States Texas A and M University Nuclear Engineering Department 3133 TAMU College StationTX United States

ISBN: (纸本)9780894487699

Linear-multifrequency grey (LMFG) acceleration is commonly used in thermal radiation transport (TRT) to accelerate convergence of the radiation intensity. LMFG was developed assuming either no scattering or converged Thomson (within-group only) scattering. We derive and test variations of LMFG that support the more general Compton scattering, which has group-to-group coupling. We test combinations of LMFG and within-group DSA to approximately converge the Compton scattering before LMFG is applied. Comparisons of spectral radii between an analytic Fourier analysis and a numerical implementation in the Capsaicin code show good agreement. Effectively combining DSA and LMFG were seen to reduce spectral radii from above 0.95 to below 0.61, with more reduction at lower temperatures. © 2019 American Nuclear Society. All rights reserved.

关键词： Compton scattering

来源：评论

学校读者我要写书评

暂无评论

Using a low-fidelity potential flow model as a surrogate for a high-fidelity viscous flow model 48th

Using a low-fidelity potential flow model as a surrogate for...

引用

48th AIAA Fluid Dynamics Conference, 2018

作者： Rossetti, Jack S. Dannenhoffer, John F. Aerospace Computational Methods Laboratory Syracuse University Mechanical and Aerospace Engineering SyracuseNY13244 United States

ISBN: (数字)9781624105531

ISBN: (纸本)9781624105531

In current engineering fluid flow systems, space is restricted and turning a fluid while trying to minimize pressure loss and maintain flow uniformity can be a challenge. Attempts to solve this problem have mainly been through the use of a trail and error methodology both experimentally and numerically, which invokes some experiential knowledge or intuition. With recent developments in design optimization research, certain methods can now be used to remove the qualitative and imprecise nature of intuition and experience. Since this problem involves finding the shape of the vanes as well as their number and distribution, it seems appropriate to investigate it using a topology optimization technique. Topology optimization presents a general design optimization approach that can produce non-conventional designs. This technique has been used in the structural dynamics field for the design of bridges and aerodynamic structures, among others. Recently, the fluid dynamics community has adopted topology optimization for low to moderate Reynolds number flows. These applications mainly consider the design of channel walls and not the design of the internal structures with fixed boundaries, like turning vanes for a fluid flow system. Design of turning vanes is an important issue for engineering applications due to size and space constraints. Developing tools to optimize these designs can reduce costs and produce more efficient fluid flow systems for heating and cooling or fuel injection. In this study, a topology optimization technique using a low-fidelity potential flow model as a surrogate for a high-fidelity viscous flow model is proposed with the goal of finding the optimal design and layout of turning vanes in moderate to high Reynolds number flow. © 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Topology

来源：评论

学校读者我要写书评

暂无评论

Ion friction at small values of the Coulomb logarithm

引用

Physical Review E 2019年第5期99卷 053206-053206页

作者： Tucker Sprenkle Adam Dodson Quinton McKnight Ross Spencer Scott Bergeson Abdourahmane Diaw Michael S. Murillo Department of Physics and Astronomy Brigham Young University Provo Utah 84602 USA Computational Physics and Methods Group Los Alamos National Laboratory Los Alamos New Mexico 87544 USA Department of Computational Mathematics Science and Engineering Michigan State University East Lansing Michigan 48824 USA

Transport properties of high-energy-density plasmas are influenced by the ion collision rate. Traditionally, this rate involves the Coulomb logarithm, lnΛ. Typical values of lnΛ are ≈10–20 in kinetic theories where transport properties are dominated by weak-scattering events caused by long-range forces. The validity of these theories breaks down for strongly coupled plasmas, when lnΛ is of order one. We present measurements and simulations of collision data in strongly coupled plasmas when lnΛ is small. Experiments are carried out in the first dual-species ultracold neutral plasma (UNP), using Ca+ and Yb+ ions. We find strong collisional coupling between the different ion species in the bulk of the plasma. We simulate the plasma using a two-species fluid code that includes Coulomb logarithms derived from either a screened Coulomb potential or a the potential of mean force. We find generally good agreement between the experimental measurements and the simulations. With some improvements, the mixed Ca+ and Yb+ dual-species UNP will be a promising platform for testing theoretical expressions for lnΛ and collision cross-sections from kinetic theories through measurements of energy relaxation, stopping power, two-stream instabilities, and the evolution of sculpted distribution functions in an idealized environment in which the initial temperatures, densities, and charge states are accurately known.

关键词： Hot dense plasma Ion-inertial confinement Low-temperature plasma Random & disordered media Strongly-coupled plasmas Warm-dense matter Atom & ion cooling Optical plasma measurements Particle-in-cell methods Time-resolved light scattering spectroscopy Two-fluid & multi-fluid model

来源：评论

学校读者我要写书评

暂无评论

A highly parallel multilevel Newton-Krylov-Schwarz method with subspace-based coarsening and partition-based balancing for the multigroup neutron transport equations on 3D unstructured meshes

arXiv

引用

arXiv 2019年

作者： Kong, Fande Wang, Yaqi Gaston, Derek R. Permann, Cody J. Slaughter, Andrew E. Lindsay, Alexander D. Martineau, Richard C. Computational Frameworks Idaho National Laboratory Idaho FallsID83415 United States Nuclear Engineering Methods Development Idaho National Laboratory Idaho FallsID83415 United States

The multigroup neutron transport equations have been widely used to study the motion of neutrons and their interactions with the background materials. Numerical simulation of the multigroup neutron transport equations is computationally challenging because the equations is defined on a high dimensional phase space (1D in energy, 2D in angle, and 3D in spatial space), and furthermore, for realistic applications, the computational spatial domain is complex and the materials are heterogeneous. The multilevel domain decomposition methods is one of the most popular algorithms for solving the multigroup neutron transport equations, but the construction of coarse spaces is expensive and often not strongly scalable when the number of processor cores is large. A scalable algorithm has to be designed in such a way that the compute time is almost halved without any comprise on the solution accuracy when the number of processor cores is doubled. In this paper, we study a highly parallel multilevel Newton-Krylov-Schwarz method equipped with several novel components, such as subspace-based coarsening, partition-based balancing and hierarchical mesh partitioning, that enable the overall simulation strongly scalable in terms of the compute time. Compared with the traditional coarsening method, the subspace-based coarsening algorithm significantly reduces the cost of the preconditioner setup that is often unscalable. In addition, the partition-based balancing strategy enhances the parallel efficiency of the overall solver by assigning a nearly-equal amount of work to each processor core. The hierarchical mesh partitioning is able to generate a large number of subdomains and meanwhile minimizes the off-node communication. We numerically show that the proposed algorithm is scalable with more than 10,000 processor cores for a realistic application with a few billions unknowns on 3D unstructured meshes. Copyright © 2019, The Authors. All rights reserved.

关键词： Ostwald ripening

来源：评论

学校读者我要写书评

暂无评论

Bump-on-tail instability across coupling and interaction-range regimes

引用

Physical Review Research 2019年第3期1卷 033166-033166页

作者： Joseph J. Williams Gautham Dharuman Mathieu Marciante James Hamilton Cooley Michael S. Murillo Department of Aerospace Engineering and Department of Mathematics University of Texas Austin Texas 78705 USA Department of Computational Mathematics Science and Engineering Michigan State University East Lansing Michigan 48824 USA Computational Physics and Methods Group Los Alamos National Laboratory Los Alamos New Mexico 87545 USA

The impact of collisionality and the range of the interparticle interaction on the bump-on-tail instability is examined both computationally and theoretically. Using three-dimensional, nonequilibrium molecular dynamics with a force law that varies continuously from long range (pure 1/r Coulomb limit) to short range and across coupling regimes from weakly to strongly collisional, we examine properties of the instability; unlike other computational methods, molecular dynamics includes large-angle scattering, including the extreme limit of caging, and dynamical nonlinear screening across length scales as small as the interparticle spacing. A simpler theoretical model is also developed for comparison to the molecular dynamics results; we find that the two methods agree well in the appropriate limit, revealing that molecular dynamics is an accurate tool for the exploration of plasma instabilities. Our results reveal that the bump-on-tail instability exists only for long-range interactions.

关键词： Beam-plasma instability Plasma instabilities Two-stream instability Hamiltonian systems Single-component plasmas Molecular dynamics

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：