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Ordered and disordered stealthy hyperuniform point patterns across spatial dimensions

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arXiv 2024年

作者： Morse, Peter K. Steinhardt, Paul J. Torquato, Salvatore Department of Chemistry Princeton University PrincetonNJ08544 United States Department of Physics Princeton University PrincetonNJ08544 United States Princeton Institute of Materials Princeton University PrincetonNJ08544 United States Princeton Center for Theoretical Science Princeton University PrincetonNJ08544 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States

In previous work [Phys. Rev. X 5, 021020 (2015)], it was shown that stealthy hyperuniform systems can be regarded as hard spheres in Fourier-space in the sense that the the structure factor is exactly zero in a spherical region around the origin in analogy with the pair-correlation function of real-space hard spheres. In this work, we exploit this correspondence to confirm that the densest Fourier-space hard-sphere system is that of a Bravais lattice. This is in contrast to real-space hard-spheres, whose densest configuration is conjectured to be disordered. We also extend the virial series previously suggested for disordered stealthy hyperuniform systems to higher dimensions in order to predict spatial decorrelation as function of dimension. This prediction is then borne out by numerical simulations of disordered stealthy hyperuniform ground states in dimensions d = 2-8. © 2024, CC BY.

关键词： Ground state

A Multi-Technique Study of C2H4 Adsorption on Fe3O4(001)

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arXiv 2023年

作者： Puntscher, Lena Sombut, Panukorn Wang, Chunlei Ulreich, Manuel Pavelec, Jiri Rafsanjani-Abbasi, Ali Meier, Matthias Lagin, Adam Setvin, Martin Diebold, Ulrike Franchini, Cesare Schmid, Michael Parkinson, Gareth S. Institute of Applied Physics TU Wien Vienna Austria Faculty of Physics Center for Computational Materials Science University of Vienna Vienna Austria Department of Surface and Plasma Science Faculty of Mathematics and Physics Charles University Prague Czech Republic Dipartimento di Fisica e Astronomia Università di Bologna Bologna Italy

The adsorption/desorption of ethene (C2H4), also commonly known as ethylene, on Fe3O4(001) was studied under ultrahigh vacuum conditions using temperature programmed desorption (TPD), scanning tunneling microscopy, x-ray photoelectron spectroscopy, and density functional theory (DFT) based computations. To interpret the TPD data, we have employed a new analysis method based on equilibrium thermodynamics. C2H4 adsorbs intact at all coverages and interacts most strongly with surface defects such as antiphase domain boundaries and Fe adatoms. On the regular surface, C2H4 binds atop surface Fe sites up to a coverage of 2 molecules per (√2×√2)R45° unit cell, with every second Fe occupied. A desorption energy of 0.36 eV is determined by analysis of the TPD spectra at this coverage, which is approximately 0.1-0.2 eV lower than the value calculated by DFT+U with van der Waals corrections. Additional molecules are accommodated in between the Fe rows. These are stabilized by attractive interactions with the molecules adsorbed at Fe sites. The total capacity of the surface for C2H4 adsorption is found to be close to 4 molecules per (√2×√2)R45° unit cell. © 2023, CC BY.

关键词： Ethylene

Scaling law of mixing layer in cylindrical Rayleigh-Taylor turbulence

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Physical Review E 2021年第5期104卷 055104-055104页

作者： Zhiye Zhao Pei Wang Nan-Sheng Liu Xi-Yun Lu Department of Modern Mechanics University of Science and Technology of China Hefei Anhui 230026 China Institute of Applied Physics and Computational Mathematics Beijing 10094 China

The nonlinear evolution of mixing layer in cylindrical Rayleigh-Taylor (RT) turbulence is studied theoretically and numerically. The scaling laws including the hyperbolic cosine growth for outward mixing layer and the cosine growth for inward mixing layer of the cylindrical RT turbulence are proposed for the first time and verified reliably by direct numerical simulation of the Navier-Stokes equations. It is identified that the scaling laws for the cylindrical RT turbulence transcend the classical power law for the planar RT turbulence and can be recovered to the quadratic growth as cylindrical geometry effect vanishes. Further, characteristic time- and length scales are reasonably obtained based on the scaling laws to reveal the self-similar evolution features for the cylindrical RT turbulence.

关键词： Flow instability Rayleigh-Taylor instability Turbulence Turbulent mixing

Random Measures, ANOVA Models and Quantifying Uncertainty in Randomized Controlled Trials

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arXiv 2023年

作者： Bastian, Caleb Deen Rabitz, Herschel Rempala, Grzegorz A. Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States Department of Chemistry Princeton University PrincetonNJ08544 United States Department of Mathematics The Ohio State University ColumbusOH43210 United States Division of Biostatistics The Ohio State University ColumbusOH43210 United States

This short paper introduces a novel approach to global sensitivity analysis, grounded in the variance-covariance structure of random variables derived from random measures. The proposed methodology facilitates the application of information-theoretic rules for uncertainty quantification, offering several advantages. Specifically, the approach provides valuable insights into the decomposition of variance within discrete subspaces, similar to the standard ANOVA analysis. To illustrate this point, the method is applied to datasets obtained from the analysis of randomized controlled trials on evaluating the efficacy of the COVID-19 vaccine and assessing clinical endpoints in a lung cancer *** Codes 92-05, 92-11 Copyright © 2023, The Authors. All rights reserved.

关键词： Sensitivity analysis

Modeling ionic flow between small targets: insights from diffusion and electro-diffusion theory

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arXiv 2023年

作者： Paquin-Lefebvre, Frédéric Holcman, David Group of Data Modeling and Computational Biology IBENS École Normale Supérieure Paris75005 France Department of Applied Mathematics and Theoretical Physics Churchill College University of Cambridge CB3 0DS United Kingdom

The flow of ions through permeable channels causes voltage drop in physiological nanodomains such as synapses, dendrites and dendritic spines, and other protrusions. How the voltage changes around channels in these nanodomains has remained poorly studied. We focus this book chapter on summarizing recent efforts in computing the steady-state current, voltage and ionic concentration distributions based on the Poisson-Nernst-Planck equations as a model of electro-diffusion. We first consider the spatial distribution of an uncharged particle density and derive asymptotic formulas for the concentration difference by solving the Laplace’s equation with mixed boundary conditions. We study a constant particles injection rate modeled by a Neumann flux condition at a channel represented by a small boundary target, while the injected particles can exit at one or several narrow patches. We then discuss the case of two species (positive and negative charges) and take into account motions due to both concentration and electrochemical gradients. The voltage resulting from charge interactions is calculated by solving the Poisson’s equation. We show how deep an influx diffusion propagates inside a nanodomain, for populations of both uncharged and charged particles. We estimate the concentration and voltage changes in relations with geometrical parameters and quantify the impact of membrane *** Codes 35J05, 35J08, 35J25 Copyright © 2023, The Authors. All rights reserved.

关键词： Diffusion

An improved model of damage depth of shock-melted metal in microspall under triangular wave loading

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Chinese physics B 2021年第9期30卷 412-418页

作者： Wen-Bin Liu An-Min He Kun Wang Jian-Ting Xin Jian-Li Shao Nan-Sheng Liu Pei Wang Department of Modern Mechanics University of Science and Technology of ChinaHefei 230027China Institute of Applied Physics and Computational Mathematics Beijing 100094China Graduate School of China Academy of Engineering Physics Beijing 100088China College of Materials Science and Engineering Hunan UniversityChangsha 410082China Science and Technology on Plasma Physics Laboratory Research Center of Laser FusionChina Academy of Engineering PhysicsMianyang 621900China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China Center for Applied Physics and Technology Peking UniversityBeijing 100871China

Damage depth is an important dynamic parameter for describing the degree of material damage and is also a key fundamental issue in the field of impact compression *** present work is dedicated to the damage depth of shock-melted metal in microspall under triangular wave loading,and an improved model of damage depth considering the material's compressibility and relative movement is *** damage depth obtained from the proposed model is in good agreement with the laser-driven shock loading *** with the previous model,the proposed model can predict the damage depth of shock-melted metal in microspall more ***,two-groups of the smoothed particle hydrodynamics(SPH)simulations are carried out to investigate the effects of peak stress and decay length of the incident triangular wave on the damage depth,*** the decay length increases,the damage depth increases *** the peak stress increases,the damage depth increases nonlinearly,and the increase in damage depth gradually slows *** results of the SPH simulations adequately reproduce the results of the proposed model in terms of the damage ***,it is found that the threshold stress criterion can reflect the macroscopic characteristics of microspall of melted metal.

关键词： damage depth theoretical modeling microspall triangular wave

Data-Driven Mori-Zwanzig: Approaching a Reduced Order Model for Hypersonic Boundary Layer Transition

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arXiv 2023年

作者： Woodward, Michael Tian, Yifeng Mohan, Arvind Lin, Yen Ting Hader, Christoph Fasel, Hermann Chertkov, Misha Livescu, Daniel Graduate Interdisciplinary Program in Applied Mathematics Department of Mathematics University of Arizona TucsonAZ85721 United States Computer Computational and Statistical Sciences Division Los Alamos National Laboratory Los AlamosNM87544 United States Department of Aerospace and Mechanical Engineering University of Arizona TucsonAZ85721 United States

In this work, we apply, for the first time to spatially inhomogeneous flows, a recently developed data-driven learning algorithm of Mori-Zwanzig (MZ) operators, which is based on a generalized Koopman’s description of dynamical systems. The MZ formalism provides a mathematically exact procedure for constructing non-Markovian reduced-order models of resolved variables from high-dimensional dynamical systems, where the effects due to the unresolved dynamics are captured in the memory kernel and orthogonal dynamics. The algorithm developed in this work applies Mori’s linear projection operator and an SVD based compression to the selection of the resolved variables (equivalently, a low rank approximation of the two time covariance matrices). We show that this MZ decomposition not only identifies the same spatio-temporal structures found by DMD, but it can also be used to extract spatio-temporal structures of the hysteresis effects present in the memory kernels. We perform an analysis of these structures in the context of a laminar-turbulent boundary-layer transition flow over a flared cone at Mach 6, and show the dynamical relevance of the memory kernels. Additionally, by including these memory terms learned in our data-driven MZ approach, we show improvement in prediction accuracy over DMD at the same level of truncation and at a similar computational cost. Furthermore, an analysis of the spatio-temporal structures of the MZ operators shows identifiable structures associated with the nonlinear generation of the so-called "hot" streaks on the surface of the flared cone, which have previously been observed in experiments and direct numerical simulations. Copyright © 2023, The Authors. All rights reserved.

关键词： Dynamic mode decomposition

Fish-borne parasitic zoonoses transmission dynamics: The case of anisakiasis

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Informatics in Medicine Unlocked 2023年 38卷

作者： Mwasunda, Joshua A. Irunde, Jacob I. Stephano, Mussa A. Chacha, Chacha S. Department of Mathematics Physics and Informatics Mkwawa University College of Education P.O. Box 2513 Iringa Tanzania Department of Applied Mathematics and Computational Science The Nelson Mandela African Institution of Science and Technology P.O. Box 447 Arusha Tanzania

Anisakiasis is a fish-borne parasitic disease that poses threat to human health and food safety, affecting peoples’ livelihood and the economy of countries. In this paper, a mathematical model for transmission dynamics of anisakiasis is formulated and analyzed. The analysis shows that both the disease free and endemic equilibria exist. To study the dynamics of anisakiasis, the basic reproduction number R₀ is derived using the next generation matrix method. Lyapunov functions are used to assess the global stability of model equilibria. The disease free equilibrium is globally asymptotically stable whenever R₀<1 and unstable otherwise whereas the endemic equilibrium is globally asymptotically stable whenever R₀>1. The normalized forward sensitivity index is adopted to determine sensitivity indices of model parameters. The rate at which marine mammals release anisakid eggs η, recruitment rates for fish and crustaceans Λ_f and Λ_c, and their infection rates β_f and β_c respectively, and the rates at which marine mammals are recruited Λ_m and the rate at which susceptible marine mammals become carriers β_m are the most positive sensitive parameters. The natural death rate for marine mammals μ_m is the most negative sensitive parameter suggesting that marine mammals drive anisakiasis. Control measures implemented to control anisakiasis using improved fish treatment reveal that the number of infected humans declines significantly with improved fish treatment giving sufficient anisakiasis control. Therefore, to control anisakiasis, more efforts should be directed towards improving fish treatment which involves the use of microwaving, heating, salting, freezing and use of anthelmintic drugs. © 2023 The Author(s)

关键词： Anisakiasis Reproduction number Sensitivity analysis Stability analysis

THEORETICAL STUDY OF INELASTIC PROCESSES IN COLLISIONS OF Y AND Y+ WITH HYDROGEN ATOM

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arXiv 2023年

作者： Wang, Yu Alexeeva, Sofya Wang, Feng Liu, Ling Wu, Yong Wang, JianGuo Zhao, Gang Yakovleva, Svetlana A. Belyaev, Andrey K. School of Physics Beijing Institute of Technology Beijing100081 China CAS Key Laboratory of Optical Astronomy National Astronomical Observatories Beijing100101 China Data Center for High Energy Density Physics Institute of Applied Physics and Computational Mathematics Beijing100088 China Department of Theoretical Physics and Astronomy Herzen University St Petersburg191186 Russia

Utilizing a simplified quantum model approach, the low-energy inelastic collision processes between yttrium atoms (ions) and hydrogen atoms have been studied. Rate coefficients corresponding to the mutual neutralization, ion-pair formation, excitation, and de-excitation processes for the above collision systems have been provided in the temperature range of 1000-10000K. 3 ionic states and 73 covalent states are considered in calculations for the collisions of yttrium atoms with hydrogen atoms, which include 6 molecular symmetries and 4074 partial inelastic reaction processes. For the collisions of yttrium ions with hydrogen atoms, 1 ionic state and 116 covalent states are included, which related to 3 molecular symmetries and 13572 partial inelastic collision processes. It is found that the rate coefficients for the mutual neutralization process have a maximum at T = 6000K, which is an order of magnitude higher than those of other processes. Notably, the positions of optimal windows for the collisions of yttrium atoms and ions with hydrogen atoms are found near electronic binding energy -2eV (Y) and -4.4eV (Y+), respectively. The scattering channels located in or near these optimal windows have intermediate-to-large rate coefficients (greater than 10−12 cm3s−1). The reported data should be useful in the study of non-local thermodynamic equilibrium modeling. © 2023, CC BY.

关键词： Atoms