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arXiv 2022年

作者： Wang, Biyi An, Hengbin Xie, Hehu Mo, Zeyao Institute of Applied Physics and Computational Mathematics Beijing100094 China Graduate School of China Academy of Engineering Physics Beijing100088 China Caep Software Center for High Performance Numerical Simulation Beijing100088 China Icmsec Lsec Ncmis Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China School of Mathematical Sciences University of Chinese Academy of Sciences Beijing100049 China

It is needed to solve generalized eigenvalue problems (GEP) in many applications, such as the numerical simulation of vibration analysis, quantum mechanics, electronic structure, etc. The subspace iteration is a kind of widely used algorithm to solve eigenvalue problems. To solve the generalized eigenvalue problem, one kind of subspace iteration method, Chebyshev-Davidson algorithm, is proposed recently. In Chebyshev-Davidson algorithm, the Chebyshev polynomial filter technique is incorporated in the subspace iteration [15]. In this paper, based on Chebyshev-Davidson algorithm, a new subspace iteration algorithm is constructed. In the new algorithm, the Chebyshev filter and inexact Rayleigh quotient iteration techniques are combined together to enlarge the subspace in the iteration. Numerical results of a vibration analysis problem show that the number of iteration and computing time of the proposed algorithm is much less than that of the Chebyshev-Davidson algorithm and some typical GEP solution algorithms. Furthermore, the new algorithm is more stable and reliable than the Chebyshev-Davidson algorithm in the numerical *** Codes 65F15, 65N25, 65H17 Copyright © 2022, The Authors. All rights reserved.

关键词： Vibration analysis

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Buildup time of Autler-Townes splitting in attosecond transient absorption spectroscopy

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Physical Review A 2021年第6期103卷 L061102-L061102页

作者： Xiaoxia Wu Zengqiang Yang Shaofeng Zhang Xinwen Ma Jie Liu Difa Ye Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China University of Chinese Academy of Sciences Beijing 100049 China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China Department of Physics School of Arts and Sciences Shaanxi University of Science and Technology Xi'an 710021 China Graduate School China Academy of Engineering Physics Beijing 100193 China

Although the time-dependent buildup processes of Autler-Townes splitting in attosecond transient absorption spectra have been observed in plenty of experiments, there still exists an open question of when the splitting is maximized, which tells us how fast the system responds to the pump field and how well the adiabatic following is in a slowly varying few-cycle laser pulse. In this Letter we work out a compact formula to quantify the buildup time of the Autler-Townes splitting, which is related to multiple timescales of the laser-atom system, e.g., the Rabi period, the laser cycle, and the pulse duration, according to a universal power law. This scaling law applies not only to singly excited states, but also to doubly excited states in which complex electron-electron interaction gets involved. Our findings have potential applications in calibrating the zero delay in a transient absorption spectroscopy.

关键词： Nonlinear optics Optical transient phenomena Stark effect Ultrafast optics Ultrafast phenomena Adiabatic approximation Rotating wave approximation Schroedinger equation Two-level models

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Random-walk shielding-potential viscosity model for warm dense metals

arXiv

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arXiv 2021年

作者： Cheng, Yuqing Liu, Haifeng Hou, Yong Meng, Xujun Li, Qiong Liu, Yu Gao, Xingyu Yuan, Jianmin Song, Haifeng Wang, Jianguo School of Mathematics and Physics University of Science and Technology Beijing Beijing100083 China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing100094 China Department of Physics College of Liberal Arts and Sciences National University of Defense Technology Changsha410073 China Graduate School China Academy of Engineering Physics Beijing100193 China

We develop a novel model, called the "random-walk shielding-potential viscosity model" (RWSP-VM) that introduces the statistics of random-walk ions and the Debye shielding effect to describe the viscosities of warm dense metals. The viscosities of several metals with low to high atomic number (Be, Al, Fe, and U) are calculated using the analytical expression of RWSP-VM. Additionally, we simulate the viscosities of Fe and Be by employing the Langevin molecular dynamics (MD) and classical MD, while the MD data for Al and U are obtained from a previous work. The results of the RWSP-VM are in good agreement with the MD results, which validates the proposed model. Furthermore, we compare the RWSP-VM with the one-component plasma model and Yukawa viscosity model and show that the three models yield results in excellent agreement with each other in the regime where the RWSP-VM is applicable. These results indicate that the RWSP-VM is a universal, accurate, and highly efficient model for calculating the viscosity of metals in the warm dense state. The code of the proposed RWSP-VM is provided, and it is envisaged that it will have broad application prospects in numerous fields. © 2021, CC BY-NC-ND.

关键词： Shielding

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Target Density Effects on Charge Transfer of Laser-Accelerated Carbon Ions in Dense Plasma

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Physical Review Letters 2023年第9期130卷 095101-095101页

作者： Jieru Ren Bubo Ma Lirong Liu Wenqing Wei Benzheng Chen Shizheng Zhang Hao Xu Zhongmin Hu Fangfang Li Xing Wang Shuai Yin Jianhua Feng Xianming Zhou Yifang Gao Yuan Li Xiaohua Shi Jianxing Li Xueguang Ren Zhongfeng Xu Zhigang Deng Wei Qi Shaoyi Wang Quanping Fan Bo Cui Weiwu Wang Zongqiang Yuan Jian Teng Yuchi Wu Zhurong Cao Zongqing Zhao Yuqiu Gu Leifeng Cao Shaoping Zhu Rui Cheng Yu Lei Zhao Wang Zexian Zhou Guoqing Xiao Hongwei Zhao Dieter H. H. Hoffmann Weimin Zhou Yongtao Zhao MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter School of Physics Xi’an Jiaotong University Xi’an 710049 China Science and Technology on Plasma Physics Laboratory Laser Fusion Research Center China Academy of Engineering Physics Mianyang 621900 China Advanced Materials Testing Technology Research Center Shenzhen University of Technology Shenzhen 518118 China Institute of Applied Physics and Computational Mathematics Beijing 100094 China Graduate School China Academy of Engineering Physics Beijing 100088 China Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China School of Nuclear Science and Technology University of Chinese Academy Sciences Beijing 101408 China

We report on charge state measurements of laser-accelerated carbon ions in the energy range of several MeV penetrating a dense partially ionized plasma. The plasma was generated by irradiation of a foam target with laser-induced hohlraum radiation in the soft x-ray regime. We use the tricellulose acetate (C9H16O8) foam of 2 mg/cm3 density and 1 mm interaction length as target material. This kind of plasma is advantageous for high-precision measurements, due to good uniformity and long lifetime compared to the ion pulse length and the interaction duration. We diagnose the plasma parameters to be Te=17 eV and ne=4×1020 cm−3. We observe the average charge states passing through the plasma to be higher than those predicted by the commonly used semiempirical formula. Through solving the rate equations, we attribute the enhancement to the target density effects, which will increase the ionization rates on one hand and reduce the electron capture rates on the other hand. The underlying physics is actually the balancing of the lifetime of excited states versus the collisional frequency. In previous measurement with partially ionized plasma from gas discharge and z pinch to laser direct irradiation, no target density effects were ever demonstrated. For the first time, we are able to experimentally prove that target density effects start to play a significant role in plasma near the critical density of Nd-glass laser radiation. The finding is important for heavy ion beam driven high-energy-density physics and fast ignitions. The method provides a new approach to precisely address the beam-plasma interaction issues with high-intensity short-pulse lasers in dense plasma regimes.

关键词： Electronic excitation & ionization High-energy-density plasmas Plasma fusion Plasma-beam interactions Laboratory plasma Near-critical & underdense plasmas Ab initio molecular dynamics First-principles calculations in plasma physics Particle plasma measurements

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The Smart Analysis of Performing Scalable Inference for Big Data Analytics

The Smart Analysis of Performing Scalable Inference for Big ...

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International Conference on Power Energy, Environment and Intelligent Control (PEEIC)

作者： Vishakha D Bhandarkar Aruna Sri Rongali Mohamed Dawood Shamout Prof. Sachin Pund Gigih Forda Nama Shrishailappa Patil Applied Mathematics and Humanities Yeshwantrao Chavan College of Engineering India Graduate Doctoral Information Technology/Graduate (Information Technology Emphasis/Information Technology Ph.D.) University of The Cumberlands US Department of Management College of Business Administration University of Sharjah Sharjah United Arab Emirates Department of Industrial Engineering Shri Ramdeobaba College of Engineering and Management Nagpur Maharashtra India Department of Informatics Doctoral Program of Environtmental Science University of Lampung Bandar Lampung Computer engineering Vishwakarma Institute of Technology Pune

This paper examines the reproducibility of massive information analytics under particular factors. The paper proposes the “performing Scalable Inference” technique to cope with scalability troubles and to exploit current big statistics platforms for efficient computing and statistics garage of the statistics. In particular, the paper describes how to perform leak-free, parallelizable visible analytics over massive datasets using present extensive records analytics frameworks such as Apache Flink. This method presents an automated manner to execute analytics that preserves reproducibility and the ability to make adjustments without re-running the entire technique. The paper also demonstrates how these analytics may help several real-world use instances, explore affected person cohorts for studies, and develop stratified patient cohorts for hospital therapy. In the end, the paper observes how the proposed method may be exercised within the real world. Actively scalable inference for massive information analytics is pivotal in optimizing decision-making and allocation of assets. Typically, such inferences are made based on information accumulated from numerous sources, databases, unstructured data, and different digital sources. So one can ensure scalability, a complete cloud-primarily based platform has to be hired. This solution will permit the ***, deploying the essential records series and evaluation algorithms are prime here. It could permit the platform to recognize the styles inside the statistics and discover any ability correlations or traits. Additionally, predictive analytics and system mastering strategies may be incorporated to provide insights into the results of the information. In the long run, by leveraging those techniques, the platform can draw efficient inferences and appropriately compare situations in an agile and green way..

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The connection between polymer collapse and the onset of jamming

arXiv

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arXiv 2023年

作者： Grigas, Alex T. Fisher, Aliza Shattuck, Mark D. O’Hern, Corey S. Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States

Previous studies have shown that the interiors of proteins are densely packed, reaching packing fractions that are as large as those found for static packings of individual amino-acid-shaped particles. How can the interiors of proteins take on such high packing fractions given that amino acids are connected by peptide bonds and many amino acids are hydrophobic with attractive interactions? We investigate this question by comparing the structural and mechanical properties of collapsed attractive disk-shaped bead-spring polymers to those of three reference systems: static packings of repulsive disks, of attractive disks, and of repulsive disk-shaped bead-spring polymers. We show that attractive systems quenched to temperatures below the glass transition T Tg and static packings of both repulsive disks and bead-spring polymers possess similar interior packing fractions. Previous studies have shown that static packings of repulsive disks are isostatic at jamming onset, i.e. the number of contacts Nc matches the number of degrees of freedom, which strongly influences their mechanical properties. We find that repulsive polymers are hypostatic at jamming onset, but effectively isostatic when including quartic modes. While attractive disk and polymer packings are hyperstatic, we identify a definition for interparticle contacts for which they can also be considered as effectively isostatic. As a result, we show that the mechanical properties (e.g. scaling of the potential energy with excess contact number and low-frequency contribution to the density of vibrational modes) of weakly attractive disk and polymer packings are similar to those of isostatic repulsive disk and polymer packings. Our results demonstrate that static packings generated via attractive collapse or compression of repulsive particles possess similar structural and mechanical properties. © 2023, CC BY.

关键词： Amino acids

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Separating the contributions of electric and magnetic fields in deflecting the probes in proton radiography with multiple proton energies

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Matter and Radiation at Extremes 2021年第3期6卷 42-54页

作者： Bao Du Hong-Bo Cai Wen-Shuai Zhang Xiao-Fang Wang Dong-Guo Kang Luan Deng En-Hao Zhang Pei-Lin Yao Xin-Xin Yan Shi-Yang Zou Shao-Ping Zhu Institute of Applied Physics and Computational Mathematics Beijing 100094China HEDPS Center for Applied Physics and TechnologyPeking UniversityBeijing 100871China IFSA Collaborative Innovation Center Shanghai Jiao Tong UniversityShanghai 200240China Department of Engineering and Applied Physics University of Science and Technology of ChinaHefei 230026China Graduate School China Academy of Engineering PhysicsBeijing 100088China Department of Engineering Physics Tsinghua UniversityBeijing 100084China STPPL Research Center of Laser FusionChina Academy of Engineering PhysicsMianyang 621900China

In proton radiography,degeneracy of electric and magnetic fields in deflecting the probe protons can prevent full interpretation of proton flux perturbations in the detection *** this paper,theoretical analyses and numerical simulations suggest that the contributions of the electric and magnetic fields can be separately obtained by analyzing the difference between the flux distributions of two discriminated proton energies in a single shot of proton *** eliminate the influence of field evolution on the separation,a strategy is proposed in which slow field evolution is assumed or an approximate estimate of field growth is *** could help achieve a clearer understanding of the radiographic process and allow further quantitative analysis.

关键词： magnetic fields assumed

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Hybrid fluid–particle modeling of shock-driven hydrodynamic instabilities in a plasma

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Matter and Radiation at Extremes 2021年第3期6卷 24-32页

作者： Hong-bo Cai Xin-xin Yan Pei-lin Yao Shao-ping Zhu Institute of Applied Physics and Computational Mathematics Beijing 100094China Center for Applied Physics and Technology HEDPSand College of EngineeringPeking UniversityBeijing 100871China Center for Applied Physics and Technology HEDPSSchool of Physicsand College of EngineeringPeking UniversityBeijing 100871China Department of Engineering Physics Tsinghua UniversityBeijing 100084China Graduate School China Academy of Engineering PhysicsP.O.Box 2101Beijing 100088China Science and Technology on Plasma Physics Laboratory Laser Fusion Research CenterCAEP621900 MianyangChina

Shock-driven hydrodynamic instabilities in a plasma usually lead to interfacial mixing and the generation of electromagnetic fields,which are nonequilibrium processes coupling kinetics with meso-and macroscopic *** understanding and modeling of these physical processes are very challenging tasks for single-fluid hydrodynamic *** work presents a new framework that incorporates both kinetics and hydrodynamics to simulate shock waves and hydrodynamic instabilities in high-density *** this hybrid code,ions are modeled using the standard particle-in-cell method together with a Monte Carlo description of collisions while electrons are modeled as a massless fluid,with the electron heat flux and fluid–particle energy exchange being considered in the electron pressure *** high-density plasmas,Maxwell’s equations are solved using Ohm’s law instead of Ampere’s *** hybrid algorithm retains ion kinetic effects and their consequences for plasma interpenetration,shock wave propagation,and hydrodynamic ***,we investigate the shock-induced(or gravity-induced)turbulent mixing between a light and a heavy plasma,where hydrodynamic instabilities are initiated by a shock wave(or gravity).This study reveals that self-generated electromagnetic fields play a role in the formation of baroclinic vorticity along the interface and in late-time mixing of the *** results confirm the ability of the proposed method to describe shock-driven hydrodynamic instabilities in a plasma,in particular,nonequilibrium processes that involve mixing and electromagnetic fields at the interface.

关键词： hydrodynamic shock mixing

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On a Dynamic Variant of the Iteratively Regularized Gauss-Newton Method with Sequential Data

arXiv

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arXiv 2022年

作者： Chada, Neil K. Iglesias, Marco A. Lu, Shuai Werner, Frank Applied Mathematics and Computational Science Program King Abdullah University of Science and Technology Thuwal23955 Saudi Arabia School of Mathematical Sciences University of Nottingham NottinghamNG72RD United Kingdom School of Mathematical Sciences Fudan University Shanghai200433 China Institut für Mathematik University of Wuerzburg Emil–Fischer–Str. 30 Würzburg97074 Germany

For numerous parameter and state estimation problems, assimilating new data as they become available can help produce accurate and fast inference of unknown quantities. While most existing algorithms for solving those kind of ill-posed inverse problems can only be used with a single instance of the observed data, in this work we propose a new framework that enables existing algorithms to invert multiple instances of data in a sequential fashion. Specifically we will work with the well-known iteratively regularized Gauss–Newton method (IRGNM), a variational methodology for solving nonlinear inverse problems. We develop a theory of convergence analysis for a proposed dynamic IRGNM algorithm in the presence of Gaussian white noise. We combine this algorithm with the classical IRGNM to deliver a practical (hybrid) algorithm that can invert data sequentially while producing fast estimates. Our work includes the proof of well-definedness of the proposed iterative scheme, as well as various error bounds that rely on standard assumptions for nonlinear inverse problems. We use several numerical experiments to verify our theoretical findings, and to highlight the benefits of incorporating sequential data. The context of the numerical experiments comprises various parameter identification problems including a Darcy flow PDE, and that of electrical impedance tomography. © 2022, CC BY-NC-SA.

关键词： Inverse problems

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Virtual Flavonoids Screening Identifies Potent Compounds Against Enterovirus A71 and Coxsackievirus A16

SSRN

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SSRN 2023年

作者： Sripattarphan, Amita Sanachai, Kamonpan Chavasiri, Warinthorn Wolschann, Peter Langer, Thierry Boonyasuppayakorn, Siwaporn Rungrotmongkol, Thanyada Center of Excellence in Structural and Computational Biology Department of Biochemistry Faculty of Science Chulalongkorn University Bangkok10330 Thailand Department of Biochemistry Faculty of Science Khon Kaen University Khon Kaen40002 Thailand Center of Excellence in Natural Products Chemistry Department of Chemistry Faculty of Science Chulalongkorn University Bangkok10330 Thailand Department of Pharmaceutical Chemistry Faculty of Life Sciences University of Vienna Althanstraße 14 ViennaA-1090 Austria Institute of Theoretical Chemistry University of Vienna Vienna1090 Austria Center of Excellence in Applied Medical Virology Department of Microbiology Faculty of Medicine Chulalongkorn University Bangkok10330 Thailand Program in Bioinformatics and Computational Biology Graduate School Chulalongkorn University Bangkok10330 Thailand

Worldwide outbreaks of hand, foot, and mouth disease (HFMD) are caused by enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16). Since no anti-HFMD drugs are currently available, it is interesting to study potential viral inhibitors. Rupintrivir is a rhinovirus 3C protease (3Cpro) inhibitor with apparent inhibitory activity against HFMD. This study constructs pharmacophore models of the EV-A71 and CV-A16 3Cpro complexed with rupintrivir using molecular dynamics (MD) simulations. Both models had similar pharmacophore features, including hydrogen bond donors and acceptors and hydrophobic interactions. These pharmacophore models were then used as a template to screen 39 flavonoid compounds as potential novel inhibitors. Diosmin, epigallocatechin gallate (EGCG), and RTH-011 showed high binding affinities for EV-A71 and CV-A16 3Cpro. They formed hydrogen bonds with important surrounding residues in both proteins, including H40, L127, T142, A144, T145, H161, I162, G163, and G164. In addition, their effective concentrations against rhabdomyosarcoma (RD) cell infection by EV-A71 and CV-A16 were determined. EGCG had the highest half maximal effective concentration (EC50) of 12.86 ± 1.30 µM for EV-A71 and 15.54 ± 1.50 µM for CV-A16, while diosmin had EC50 of 21.01±1.57 µM for EV-A71 and 30.68 ± 3.25 µM for CV-A16. Both compounds were non-toxic in RD cells, with 50% cytotoxic concentrations of >100 µM for EGCG and >500 µM for diosmin. In addition, MD simulation analysis showed that EGCG had a higher binding affinity than diosmin, supported by its significantly lower solvated binding free energies and greater numbers of contact atoms and key binding residues. Moreover, previous studies reported EGCG’s inhibitory effect on other viruses, such as severe acute respiratory syndrome coronavirus 2. Therefore, our findings suggest that EGCG can effectively inhibit the EV-A71 and CV-A16 3Cpro. © 2023, The Authors. All rights reserved.

关键词： Molecular dynamics

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