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arXiv 2021年

作者： Hu, Yanbo Li, Jiequan Department of Mathematics Hangzhou Normal University Hangzhou311121 China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing100088 China Center for Applied Physics and Technology Peking University 100871 China

We construct a supersonic-sonic smooth patch solution for the two dimensional steady Euler equations in gas dynamics. This patch is extracted from the Frankl problem in the study of transonic flow with local supersonic bubble over an airfoil. Based on the methodology of characteristic decompositions, we establish the global existence and regularity of solutions in a partial hodograph coordinate system in terms of angle variables. The original problem is solved by transforming the solution in the partial hodograph plane back to that in the physical plane. Moreover, the uniform regularity of the solution and the regularity of an associated sonic curve are also verified. Copyright © 2021, The Authors. All rights reserved.

关键词： Euler equations

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Sonic-supersonic solutions for the two-dimensional steady full Euler equations

arXiv

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arXiv 2019年

This paper focuses on the structure of classical sonic-supersonic solutions near sonic curves for the two-dimensional full Euler equations in gas dynamics. In order to deal with the parabolic degeneracy near the sonic curve, a novel set of dependent and independent variables are introduced to transform the Euler equations into a new system of governing equations which displays a clear regularity-singularity structure. With the help of technical characteristic decompositions, the existence of a local smooth solution for the new system is first established in a weighted metric space by using the iteration method and then expressed in terms of the original physical variables. This is the first time to construct a classical sonic-supersonic solution near a sonic curve for the full Euler *** Codes 35L65, 35L80, 76H05 Copyright © 2019, The Authors. All rights reserved.

关键词： Topology

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Cosmological phase-space analysis of f(G)-theories of gravity

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Journal of High Energy Astrophysics 2025年 47卷

作者： Papagiannopoulos, Giannis Luongo, Orlando Leon, Genly Paliathanasis, Andronikos Department of Physics National & Kapodistrian University of Athens Zografou Campus GR Athens 157 73 Greece School of Science and Technology University of Camerino Via Madonna delle Carceri Camerino 62032 Italy Department of Nanoscale Science and Engineering University at Albany-SUNY Albany 12222 NY United States INAF - Osservatorio Astronomico di Brera Milano Italy Istituto Nazionale di Fisica Nucleare (INFN) Sezione di Perugia Perugia 06123 Italy Al-Farabi Kazakh National University Al-Farabi av. 71 Almaty 050040 Kazakhstan Departamento de Matemáticas Universidad Católica del Norte Avda. Angamos 0610 Casilla 1280 Antofagasta Chile Department of Mathematics Faculty of Applied Sciences Durban University of Technology Durban 4000 South Africa School for Data Science and Computational Thinking Department of Mathematical Sciences Stellenbosch University Stellenbosch 7602 South Africa

The impact of topological terms that modify the Hilbert-Einstein action is here explored by virtue of a further f(G) contribution. In particular, we investigate the phase-space stability and critical points of an equivalent scalar field representation that makes use of a massive field, whose potential is function of the topological correction. To do so, we introduce to the gravitational Action Integral a Lagrange multiplier and model the modified Friedmann equations by virtue of new non-dimensional variables. We single out dimensionless variables that permit a priori the Hubble rate change of sign, enabling regions in which the Hubble parameter either vanishes or becomes negative. In this respect, we thus analyze the various possibilities associated with a universe characterized by such topological contributions and find the attractors, saddle points and regions of stability, in general. The overall analysis is carried out considering the exponential potential first and then shifting to more complicated cases, where the underlying variables do not simplify. We compute the eigenvalues of our coupled differential equations and, accordingly, the stability of the system, in both a spatially-flat and non-flat universe. Quite remarkably, regardless of the spatial curvature, we show that a stable de Sitter-like phase that can model current time appears only a small fraction of the entire phase-space, suggesting that the model under exam is unlikely in describing the whole universe dynamics, i.e., the topological terms appear disfavored in framing the entire evolution of the universe. © 2025 The Author(s)

关键词： Equilibrium points f(G)-gravity Gauss-Bonnet

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Temperature-dependent lattice dynamics in polycrystalline ZrN

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Physical Review B 2025年第18期111卷 184316-184316页

作者： Shaofei Wang Mark A. Mathis Chris A. Marianetti J. Matthew Mann David B. Turner Douglas L. Abernathy Raphaël P. Hermann Michael E. Manley Materials Science and Technology Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Computational Physics Division Los Alamos National Laboratory Los Alamos New Mexico 87545 USA Department of Applied Physics and Applied Mathematics Columbia University New York New York 10027 USA Air Force Research Laboratory Sensors Directorate Wright-Patterson AFB Ohio 45433 USA Azimuth Corporation Fairborn Ohio 45324 USA Neutron Scattering Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA

Zirconium nitride holds promise for improving nuclear reactor components, where thermal conductivity is important, highlighting the need for a detailed understanding of its phonons. However, the phonon dispersion derived from previous inelastic neutron scattering data is in disagreement with modern theoretical calculations, pointing to the necessity for further experimental validation. Here, we use inelastic neutron scattering experiments on polycrystalline ZrN at 6, 100, 300, 400, and 600 K, and density functional theory (DFT) calculations to study the momentum-resolved scattering and the phonon density of states. Both experimental and theoretical results reveal a phonon cutoff energy near 65 meV, in stark disagreement with previous single-crystal neutron scattering measurements indicating a cutoff near 75 meV. The 65 meV cutoff energy is, however, in reasonable agreement with previous measurements on ZrN0.9. Consistency between our theoretical and experimental results confirms that ZrN is a wide phonon band gap system and that DFT provides a reliable description of its phonons.

关键词： Inelastic neutron scattering

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DeePMD-kit v3: A Multiple-Backend Framework for Machine Learning Potentials

arXiv

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arXiv 2025年

作者： Zeng, Jinzhe Zhang, Duo Peng, Anyang Zhang, Xiangyu He, Sensen Wang, Yan Liu, Xinzijian Bi, Hangrui Li, Yifan Cai, Chun Zhang, Chengqian Du, Yiming Zhu, Jia-Xin Mo, Pinghui Huang, Zhengtao Zeng, Qiyu Shi, Shaochen Qin, Xuejian Yu, Zhaoxi Luo, Chenxing Ding, Ye Liu, Yun-Pei Shi, Ruosong Wang, Zhenyu Bore, Sigbjørn Løland Chang, Junhan Deng, Zhe Ding, Zhaohan Han, Siyuan Jiang, Wanrun Ke, Guolin Liu, Zhaoqing Lu, Denghui Muraoka, Koki Oliaei, Hananeh Singh, Anurag Kumar Que, Haohui Xu, Weihong Xu, Zhangmancang Zhuang, Yong-Bin Dai, Jiayu Giese, Timothy J. Jia, Weile Xu, Ben York, Darrin M. Zhang, Linfeng Wang, Han School of Artificial Intelligence and Data Science Unversity of Science and Technology of China Hefei China 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 Beijing China Baidu Inc. Beijing China Department of Computer Science University of Toronto TorontoON Canada Department of Chemistry Princeton University PrincetonNJ08540 United States University of Chinese Academy of Sciences Beijing100871 China State Key Laboratory of Physical Chemistry of Solid Surfaces iChEM College of Chemistry and Chemical Engineering Xiamen University Xiamen361005 China College of Integrated Circuits Hunan University Changsha410082 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Center for Smart Materials and Device Integration School of Material Science and Engineering Wuhan University of Technology Wuhan430070 China College of Science National University of Defense Technology Changsha410073 China Hunan Key Laboratory of Extreme Matter and Applications National University of Defense Technology Changsha410073 China ByteDance Research Beijing100098 China Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo315201 China College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences Beijing100049 China Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education College of Chemistry Beijing Normal University Beijing100875 China Department of Geosciences Princeton University PrincetonNJ08544 United States Department of Applied Physics and Applied Mathematics Columbia University New YorkNY10027 United States IKKEM Fujian Xiamen361005 China Graduate

In recent years, machine learning potentials (MLPs) have become indispensable tools in physics, chemistry, and materials science, driving the development of software packages for molecular dynamics (MD) simulations and related applications. These packages, typically built on specific machine learning frameworks such as TensorFlow, PyTorch, or JAX, face integration challenges when advanced applications demand communication across different frameworks. The previous TensorFlow-based implementation of DeePMD-kit exemplified these limitations. In this work, we introduce DeePMD-kit version 3, a significant update featuring a multi-backend framework that supports TensorFlow, PyTorch, JAX, and PaddlePaddle backends, and demonstrate the versatility of this architecture through the integration of other MLPs packages and of Differentiable Molecular Force Field. This architecture allows seamless backend switching with minimal modifications, enabling users and developers to integrate DeePMD-kit with other packages using different machine learning frameworks. This innovation facilitates the development of more complex and interoperable workflows, paving the way for broader applications of MLPs in scientific research. Copyright © 2025, The Authors. All rights reserved.

关键词： Molecular dynamics

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Commissioning and operation of the first high average power THz free electron laser in China 9

Commissioning and operation of the first high average power ...

引用

9th International Symposium on Ultrafast Phenomena and Terahertz Waves, ISUPTW 2018

作者： Li, Ming Yang, Xinfan Xu, Zhou Shu, Xiaojian Lu, Xiangyang Huang, Wenhui Wang, Hanbin Shen, Xuming Shan, Lijun Deng, Derong Xu, Yong Wu, Dai Xiao, Dexin Wang, Jianxin Luo, Xing Zhou, Kui Lao, Chenglong Li, Peng Lin, Sifen He, Tianhui Zhang, Peng Liu, Jie Institute of Applied Electronics China Academy of Engineering Physics Mianyang621900 China Sichuan Defense Science and Technology Industry Office Chengdu610051 China Institute of Applied Physics and Computational Mathematics Beijing100094 China Institute of Heavy Ion Physics Peking University Beijing100871 China Department of Engineering Physics Tsinghua University Beijing10084 China

ISBN: (纸本)9780960038084

China Academy of Engineering physics tera-hertz free electron laser (CAEP THz FEL, CTFEL) is the first THz FEL oscillator in China, which was jointly built by CAEP, Peking university and Tsinghua university. This THz FEL facility consists of a GaAs photocathode high-voltage DC gun, a superconducting RF linac, a planar undulator and a quasi-concentric optical resonator. The terahertz lasers frequency is continuous adjustable from 2 THz to 3 THz. The macro-pulse average power is more than 10 W and the micro-pulse power is more than 0.5 MW. © 2018 The Author(s).

关键词： Free electron lasers

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Manifold learning-based methods for analyzing single-cell RNA-sequencing data

引用

Current Opinion in Systems Biology 2018年 7卷 36-46页

作者： Moon, Kevin R. Stanley, Jay S. Burkhardt, Daniel van Dijk, David Wolf, Guy Krishnaswamy, Smita Department of Genetics Yale University New Haven CT United States Applied Mathematics Program Yale University New Haven CT United States Computational Biology and Bioinformatics Program Yale University New Haven CT United States Department of Computer Science Yale University New Haven CT United States

Recent advances in single-cell RNA sequencing technologies enable deep insights into cellular development, gene regulation, and phenotypic diversity by measuring gene expression for thousands of cells in a single experiment. While these technologies hold great potential for improving our understanding of cellular states and progression, they also pose new challenges and require advanced mathematical and algorithmic tools to extract underlying biological signals. In this review, we cover one of the most promising avenues of research into unlocking the potential of scRNA-seq data: the field of manifold learning, and the related manifold assumption in data analysis. Manifold learning provides a powerful structure for algorithmic approaches to process the data, extract its dynamics, and infer patterns in it. In particular, we cover manifold learning-based methods for denoising the data, revealing gene interactions, extracting pseudotime progressions with model fitting, visualizing the cellular state space via dimensionality reduction, and clustering the data. © 2017 Published by Elsevier Ltd.

关键词： Data mining Gene regulatory networks Imputation Manifold learning Pseudotime trends Single cell RNA sequencing

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Controlling Rydberg excitation process with shaped intense ultrashort laser pulses

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Chinese physics B 2019年第8期28卷 79-83页

作者： Xiao-Yun Zhao Chun-Cheng Wang Shi-Lin Hu Wei-Dong Li Jing Chen Xiao-Lei Hao Institute of Theoretical Physics and Department of Physics State Key Laboratory of Quantum Optics and Quantum Optics DevicesCollaborative Innovation Center of Extreme OpticsShanxi UniversityTaiyuan 030006China Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China Laboratory of Quantum Engineering and Quantum Metrology School of Physics and AstronomySun Yat-Sen University (Zhuhai Campus)Zhuhai 519082China CAPT HEDPSand IFSA Collaborative Innovation Center of MoECollege of EngineeringPeking UniversityBeijing 100084China Institute of Applied Physics and Computational Mathematics Beijing 100088China

We perform a theoretical investigation on the control over the atomic excitation of Rydberg states with shaped intense ultrashort laser pulses. By numerically solving the time-dependent Schr?dinger equation（TDSE）, we systematically study the dependence of the population of the Rydberg states on the π phase step position in the frequency spectra of the laser pulse for different intensities, central wavelengths and pulse durations. Our results show that the Rydberg excitation process can be effectively modulated using shaped intense laser pulses with the laser intensity as high as 1 × 1014 W/cm2. Our work also have benefit to the future investigation to find out the dominant mechanism behind the excitation of Rydberg states in strong laser fields.

关键词： shaped laser pulse Rydberg states excitation intense field

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Reducing bias and variance for CTF estimation in single particle cryo-EM

arXiv

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arXiv 2019年

作者： Heimowitz, Ayelet Andén, Joakim Singer, Amit Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States Center for Computational Mathematics Flatiron Institute New YorkNY10010 United States Program in Applied and Computational Mathematics Department of Mathematics Princeton University PrincetonNJ08544 United States

When using an electron microscope for imaging of particles embedded in vitreous ice, the recorded image, or micrograph, is a significantly degraded version of the tomographic projection of the sample. Apart from noise, the image is affected by the optical configuration of the microscope. This transformation is typically modeled as a convolution with a point spread function. The Fourier transform of this function, known as the contrast transfer function (CTF), is oscillatory, attenuating and amplifying different frequency bands, and sometimes flipping their signs. High-resolution reconstruction requires this CTF to be accounted for, but as its form depends on experimental parameters, it must first be estimated from the micrograph. We present a new method for CTF estimation based on multitaper methods, which reduces bias and variance in the estimate. We also use known properties of the CTF and the background noise power spectrum to further reduce the variance through background subtraction and steerable basis projection. We show that the resulting power spectrum estimates better capture the zero-crossings of the CTF and yield accurate CTF estimates on several experimental micrographs. Copyright © 2019, The Authors. All rights reserved.

关键词： Linear programming

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Web-Based Comprehensive Assessment for Postpartum Care using Rule-Based Algorithm 1

Web-Based Comprehensive Assessment for Postpartum Care using...

引用

1st International Conference on Computer, Science, Engineering and Technology, ICComSET 2018

作者： Mujahidah, S. Suryono, S. Widyawati, M.N. Department of Midwifery STIKES Karya Husada Semarang Indonesia Department of Physics Faculty of Mathematics and Natural Sciences Universitas Diponegoro Indonesia Postgraduate Program in Applied Midwifery Science Poltekkes Kemenkes Semarang Indonesia

Administration of postpartum care has been performed in line with health care standards. Unfortunately the health service medical record data is still *** results in delays in establishing a diagnosis and providing therapy which results in a worsening of the postpartum mother's *** paper proposes a web-based information system that may become one solution in solving the remaining issues in postpartum care. The system developed here is expected to improve health care quality with better data completion of postpartum mothers and access to them. The system developed here is web-based, in that it applies the rule-based artificial intelligence system. Input of the system are results of physical examination performed by medical professionals. Then processed using the rule-based algorithm to produce diagnosis and proper recommendation. This research is quasi-experimental using posttest only with control group. There were 40 were categorized into intervention group (n=20) who used the information system and control group (n=20) who used the present system endorsed by the government.. The rule-based algorithm in the information system uses validation from experts. Results show that the information system developed here is capable of solving the issue of incomprehensive data, as well as effectiveness in providing postpartum care. © 2019 IOP Publishing Ltd. All rights reserved.

关键词： Diagnosis

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