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High-throughput investigations of configurational-transformation-dominated serrations in CuZr/Cu nanolaminates

Journal of Materials Science & Technology 2020年第18期52卷 192-199页

作者： William Yi Wang Bin Gana Deye Lin Jun Wang Yiguang Wang Bin Tang Hongchao Kou Shunli Shang Yi Wang Xingyu Gao Haifeng Song Xidong Hui Laszlo J.Kecskes Zhenhai Xia Karin A.Dahmen Peter K.Liaw Jinshan Lia Zi-Kui Liu State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an.710072China Beijing Key Laboratory of Advanced High Temperature Materials Central Iron and Steel Research InstituteBeijing100081China IMDEA Materials Institute Calle Eric Kandel 2GetafeMadrid28906Spain CAEP Software Center for High Performance Numerical Simulation Institute of Applied Physics and Computational MathematicsBeijing100088China Department of Materials Science and Engineering The Pennsylvania State UniversityUniversity ParkPA16802USA State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing100083China Hopkins Extreme Materials Institute Johns Hopkins UniversityBaltimoreMD21218USA Department of Physics University of Illinois at Urbana ChampaignUrbanaIL61801USA Department of Materials Science and Engineering The University of TennesseeKnoxvilleTN37996USA

Metallic amorphous/crystalline(A/C)nanolaminates exhibit excellent ductility while retaining their high ***,the underlying physical mechanisms and the resultant structural changes during plastic deformation still remain *** the present work,the structure-property relationship of CuZr/Cu A/C nanolaminates is established through integrated high-throughput micro-compression tests and molecular dynamics simulations together with high-resolution transmission electron *** serrated flow of nanolaminates results from the formation of hexagonal-close-packed(HCP)-type stacking faults and twins inside the face-centered-cubic(FCC)Cu nano-grains,the body-centered-cubic(BCC)-type ordering at their grain boundaries,and the crystallization of the amorphous CuZr *** serration behavior of CuZr/Cu A/C nanolaminates is determined by several factors,including the formation of dense dislocation networks from the multiplication of initial dislocations that formed after yielding,weak-spots-related configurational-transitions and shear-transition-zone activities,and deformation-induced *** present work provides an insight into the heterogeneous deformation mechanism of A/C nanolaminates at the atomic scale,and mechanistic base for the microstructural design of self-toughening metallic-glass(MG)-based composites and A/C nanolaminates.

关键词： Nanolaminates Serration Configurational transformation Molecular dynamics Metallic glass

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Intensity dependence of intramolecular interference from a full quantum analysis of high-order harmonic generation

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Physical Review A 2009年第3期79卷 033405-033405页

作者： Y. J. Chen J. Liu Bambi Hu Institute of Applied Physics and Computational Mathematics Beijing 100088 China Department of Physics Centre for Nonlinear Studies and The Beijing-Hong Kong-Singapore Joint Center for Nonlinear and Complex Systems (Hong Kong) Hong Kong Baptist University Kowloon Tong Hong Kong China Department of Physics Hebei Normal University Shijiazhuang 050016 China Center for Applied Physics and Technology Peking University Beijing 100084 China Department of Physics University of Houston Houston Texas 77204-5005 USA

We develop a numerical scheme to investigate the high-order harmonic generation (HHG) in intense laser-matter interactions. We represent the time-dependent wave function in the basis of the eigenstates of the field-free Hamiltonian and trace its temporal evolution. Our full quantum simulations reveal that continuum electrons with a broad energy distribution contribute equally to one harmonic and the excited state also plays an important role in the molecular HHG. These results imply a laser-intensity-dependent picture of intramolecular interference in the HHG.

关键词： Excited states

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Learning equations from biological data with limited time samples

arXiv

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arXiv 2020年

作者： Nardini, John T. Lagergren, John H. Hawkins-Daarud, Andrea Curtin, Lee Morris, Bethan Rutter, Erica M. Swanson, Kristin R. Flores, Kevin B. Department of Mathematics North Carolina State University RaleighNC United States Statistical and Applied Mathematical Sciences Insitute DurhamNC United States Mathematical NeuroOncology Laboratory Precision Neurotherapeutics Innovation Program Mayo Clinic PhoenixAZ United States Centre for Mathematical Medicine and Biology University of Nottingham Nottingham United Kingdom Department of Applied Mathematics University of California Merced MercedCA United States

Equation learning methods present a promising tool to aid scientists in the modeling process for biological data. Previous equation learning studies have demonstrated that these methods can infer models from rich datasets, however, the performance of these methods in the presence of common challenges from biological data has not been thoroughly explored. We present an equation learning methodology comprised of data denoising, equation learning, model selection and post-processing steps that infers a dynamical systems model from noisy spatiotemporal data. The performance of this methodology is thoroughly investigated in the face of several common challenges presented by biological data, namely, sparse data sampling, large noise levels, and heterogeneity between datasets. We find that this methodology can accurately infer the correct underlying equation and predict unobserved system dynamics from a small number of time samples when the data is sampled over a time interval exhibiting both linear and nonlinear dynamics. Our findings suggest that equation learning methods can be used for model discovery and selection in many areas of biology when an informative dataset is used. We focus on glioblastoma multiforme modeling as a case study in this work to highlight how these results are informative for data-driven modeling-based tumor invasion predictions. Copyright © 2020, The Authors. All rights reserved.

关键词： Learning systems

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Heterogeneous cellular network performance analysis under open and closed access

Heterogeneous cellular network performance analysis under op...

引用

IEEE Globecom Workshops

作者： Prasanna Madhusudhanan Juan G. Restrepo Youjian Liu Timothy X Brown Department of Electrical Computer and Energy Engineering University of Colorado Boulder CO USA Department of Applied Mathematics University of Colorado Boulder CO USA Department of Electrical Computer and Energy Engineering Interdisciplinary Telecommunications Program University of Colorado Boulder CO USA

We study the downlink signal-to-interference ratio (SIR) in a multi-tier heterogeneous cellular network under the open and closed access schemes. Each tier is characterized by a base-station (BS) arrangement according to a homogeneous Poisson point process with certain density, constant transmission power and random shadow fading factors with arbitrary distribution. The mobile-station (MS) communicates with the BS that has the maximum instantaneous received power among those to which it is allowed access. The chosen BS provides coverage to the MS if the SIR is above a certain threshold determined by the BS's tier. The coverage probability and average rate expressions are derived for the open access scheme for any arbitrary SIR threshold assigned for each tier, and for the closed access scheme when the SIR thresholds are greater than one.

关键词： Fading Macrocell networks Random variables Measurement computational modeling Femtocell networks Downlink

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Chiral Quasi-Bound States in the Continuum

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Physical Review Letters 2021年第7期126卷 073001-073001页

作者： Adam Overvig Nanfang Yu Andrea Alù Photonics Initiative Advanced Science Research Center at the Graduate Center of the City University of New York New York New York 10031 USA Department of Applied Physics and Applied Mathematics Columbia University New York New York 10027 USA Physics Program Graduate Center City University of New York New York New York 10016 USA

Quasi-bound states in the continuum (QBICs) are Fano resonant states with long optical lifetimes controlled by symmetry-breaking perturbations. While conventional Fano responses are limited to linear polarizations and do not support tailored phase control, here we introduce QBICs born of chiral perturbations that encode arbitrary elliptical polarization states and enable geometric phase engineering. We thereby design metasurfaces with ultrasharp spectral features that shape the impinging wave front with near-unity efficiency. Our findings extend Fano resonances beyond their conventional limits, opening opportunities for nanophotonics, classical and quantum optics, and acoustics.

关键词： Metamaterials Photonic crystals

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Analysis of nucleon and triton emissions from nucleon-Li7 collisions below 20 MeV

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Physical Review C 2019年第3期99卷 034602-034602页

作者： Hairui Guo Yukinobu Watanabe Takuma Matsumoto Kohei Nagaoka Kazuyuki Ogata Masanobu Yahiro Institute of Applied Physics and Computational Mathematics Beijing 100094 China Department of Advanced Energy Engineering Science Kyushu University Kasuga Fukuoka 816-8580 Japan Department of Physics Kyushu University Fukuoka 812-8581 Japan Research Center for Nuclear Physics Osaka University Ibaraki Osaka 567-0047 Japan

The understanding of nucleon (N) and triton emissions from nucleon-Li7 collision is important for the development of some fusion-related facilities. Both nucleon and triton emissions from nucleon-induced reactions on Li7 leading to three final particles at incident energies below 20 MeV are analyzed by using a three-body continuum discretized coupled-channels method (CDCC), final-state interaction (FSI) model, and sequential decay (SD) model. The CDCC is applied to predict nucleon and triton emissions via breakup continuum channels, Li7(N,N′)Li*7→t+α. Triton emission from the p(n) + Li7→t+Li5(He5) channel and nucleon emission from sequential decay of the ground-state Li5(He5) are described by the FSI model and the SD model, respectively. The double differential cross sections (DDXs) of nucleon and triton emissions are calculated and compared with experimental data. In most cases, the calculated DDXs are in good agreement with the measured ones except at relatively low nucleon emission energies. It is clarified that triton production takes place mainly via the breakup continuum channels.

关键词： Breakup reactions Direct reactions Nuclear reactions Nucleon induced nuclear reactions 6 ≤ A ≤ 19 Optical, coupled-channel & distorted wave models

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Atomistic Modelling of All Dislocations and Twins in HCP and BCC Ti

SSRN

引用

SSRN 2022年

作者： Wen, Tongqi Liu, Anwen Wang, Rui Zhang, Linfeng Han, Jian Wang, Han Srolovitz, David J. Wu, Zhaoxuan Department of Mechanical Engineering The University of Hong Kong Hong Kong Department of Materials Science and Engineering City University of Hong Kong Hong Kong DP Technology Beijing China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing China Hong Kong Institute for Advanced Study City University of Hong Kong Hong Kong

Ti exhibits complex plastic deformation controlled by active dislocation and twinning systems. Understandings on dislocation cores and twin interfaces are currently not complete or quantitative, despite extensive experimental and simulation studies. Here, we determine all the core and twin interface properties in both HCP and BCC Ti using a Deep Potential (DP) and DFT. We determine the core structures, critical resolved shear stresses and mobilities of hai, hc + ai, hci dislocations in HCP and h111i/2 dislocations in BCC Ti. The hai slip consists of slow core migration on pyramidal-I planes and fast migration on prism-planes, and is kinetically limited by cross-slips among them. This behaviour is consistent with 'locking-unlocking' phenomena in TEM and is likely an intrinsic property. Large-scale DFT calculations provide a peek at thescrew hc + ai core and glide behaviour, which is further quantified using DP-Ti. The screw hc + ai is unstable on pyramidal-II planes. The mixed hc + ai is nearly sessile on pyramidal-I planes, consistent with observations of long dislocations in this orientation. The edge and mixed hc + ai are unstable against a pyramidal-to-basal (PB) transition and become sessile at high temperatures, corroborate the difficulties in hci-axis compression of Ti. Finally, in BCC Ti, the h111i/2 screw has a degenerate core with average glide on {112} planes;the h111i/2 edge and mixed dislocations have non-dissociated cores on {110} planes. This work paints a self-consistent, complete picture on all dislocations in Ti, rationalises previous experimental observations and points to future HRTEM examinations of unusual dislocations such as the mixedand PB transformed hc + ai cores. © 2022, The Authors. All rights reserved.

关键词： Molecular dynamics

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Learning binary latent variable models: A tensor eigenpair approach

arXiv

引用

arXiv 2018年

作者： Jaffe, Ariel Weiss, Roi Carmi, Shai Kluger, Yuval Nadler, Boaz Dept. of Computer Science and Applied Mathematics Weizmann Institute of Science Rehovot7610001 Israel Braun School of Public Health and Community Medicine Hebrew University of Jerusalem Jerusalem9112102 Israel Interdepartmental Program in Computational Biology and Bioinformatics Yale University New HavenCT06511 United States Dept. of Pathology Yale Cancer Center Yale University School of Medicine New HavenCT06520 United States Program of Applied Mathematics Yale University New HavenCT06511 United States

Latent variable models with hidden binary units appear in various applications. Learning such models, in particular in the presence of noise, is a challenging computational problem. In this paper we propose a novel spectral approach to this problem, based on the eigenvectors of both the second order moment matrix and third order moment tensor of the observed data. We prove that under mild non-degeneracy conditions, our method consistently estimates the model parameters at the optimal parametric rate. Our tensor-based method generalizes previous orthogonal tensor decomposition approaches, where the hidden units were assumed to be either statistically independent or mutually exclusive. We illustrate the consistency of our method on simulated data and demonstrate its usefulness in learning a common model for population mixtures in genetics. Copyright © 2018, The Authors. All rights reserved.

关键词： Tensors

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Atomistic modelling of all dislocations and twins in HCP and BCC Ti

arXiv

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arXiv 2022年

Ti exhibits complex plastic deformation controlled by active dislocation and twinning systems. Understandings on dislocation cores and twin interfaces are currently not complete or quantitative, despite extensive experimental and simulation studies. Here, we determine all the core and twin interface properties in both HCP and BCC Ti using a Deep Potential (DP) and DFT. We determine the core structures, critical resolved shear stresses and mobilities of hai, hc + ai, hci dislocations in HCP and h111i/2 dislocations in BCC Ti. The hai slip consists of slow core migration on pyramidal-I planes and fast migration on prism-planes, and is kinetically limited by cross-slips among them. This behaviour is consistent with "locking-unlocking" phenomena in TEM and is likely an intrinsic property. Large-scale DFT calculations provide a peek at the screw hc + ai core and glide behaviour, which is further quantified using DP-Ti. The screw hc + ai is unstable on pyramidal-II planes. The mixed hc + ai is nearly sessile on pyramidal-I planes, consistent with observations of long dislocations in this orientation. The edge and mixed hc + ai are unstable against a pyramidal-to-basal (PB) transition and become sessile at high temperatures, corroborate the difficulties in hci-axis compression of Ti. Finally, in BCC Ti, the h111i/2 screw has a degenerate core with average glide on {112} planes;the h111i/2 edge and mixed dislocations have non-dissociated cores on {110} planes. This work paints a self-consistent, complete picture on all dislocations in Ti, rationalises previous experimental observations and points to future HRTEM examinations of unusual dislocations such as the mixed and PB transformed hc + ai cores. Copyright © 2022, The Authors. All rights reserved.

关键词： Molecular dynamics

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High-accuracy three-dimensional surface detection in smoothed particle hydrodynamics for free-surface flows

arXiv

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arXiv 2022年

作者： Liu, Wen-Bin Ma, Dong-Jun Qian, Jian-Zhen Zhang, Ming-Yu He, An-Min Liu, Nan-Sheng Wang, Pei Department of Modern Mechanics University of Science and Technology of China Anhui Hefei230027 China Institute of Applied Physics and Computational Mathematics Beijing100094 China Graduate School of China Academy of Engineering Physics Beijing100088 China Center for Applied Physics and Technology Peking University Beijing100871 China

In this study, we investigate high-accuracy three-dimensional surface detection in smoothed particle hydrodynamics for free-surface flows. A new geometrical method is first developed to enhance the accuracy of free-surface particle detection in complex flows. This method detects free-surface particles via continuous global scanning inside the sphere of a particle through a cone region whose vertex corresponds to the particle position. The particle is identified as a free-surface particle if there exists a cone region with no neighboring particles. Next, an efficient semi-geometrical method is proposed based on the geometrical method to reduce the computational cost. It consists of finding particles near the free surface via position divergence and then detecting these particles using the geometrical method to identify free-surface particles. The accuracy and robustness of the proposed method are demonstrated by performing tests on several model problems. © 2022, CC BY.

关键词： Hydrodynamics

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