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Viscosity in water from first-principles and deep-neural-network simulations

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arXiv 2022年

作者： Malosso, Cesare Zhang, Linfeng Car, Roberto Baroni, Stefano Tisi, Davide SISSA - Scuola Internazionale Superiore di Studi Avanzati Trieste34136 Italy Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States DP Technology Beijing100080 China Department of Chemistry Department of Physics Princeton Institute for the Science and Technology of Materials Princeton University PrincetonNJ08544 United States CNR Istituto Officina dei Materiali SISSA Unit Trieste34136 Italy

We report on an extensive study of the viscosity of liquid water at near-ambient conditions, performed within the Green-Kubo theory of linear response and equilibrium ab initio molecular dynamics (AIMD), based on density-functional theory (DFT). In order to cope with the long simulation times necessary to achieve an acceptable statistical accuracy, our ab initio approach is enhanced with deep-neural-network potentials (NNP). This approach is first validated against AIMD results, obtained by using the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional and paying careful attention to crucial, yet often overlooked, aspects of the statistical data analysis. Then, we train a second NNP to a dataset generated from the Strongly Constrained and Appropriately Normed (SCAN) functional. Once the error resulting from the imperfect prediction of the melting line is offset by referring the simulated temperature to the theoretical melting one, our SCAN predictions of the shear viscosity of water are in very good agreement with experiments. Copyright © 2022, The Authors. All rights reserved.

关键词： Deep neural networks

Early Detection of Preeclampsia using a Rule-Based System Information System 1

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Early Detection of Preeclampsia using a Rule-Based System In...

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

作者： Aini, F.N. Widyawati, M.N. Suryono, S. Purwokerto Midwifery Program Poltekkes Kemenkes Semarang Indonesia Postgraduate Applied Science Midwifery Program Poltekkes Kemenkes Semarang Indonesia Department of Physics Faculty of Science and Mathematics University Diponegoro Semarang Indonesia

Preeclampsia is the highest cause of maternal death. One program to reduce Maternal Mortality Rate (MMR) is by early detection. The incomplete history of maternal history that has occurred has led to the determination of an incorrect diagnosis and has resulted in errors in decision making. The results of the survey in the detection of preeclampsia include midwives not conducting a history of past medical history, physical examination during the first antenatal care visit is incomplete. During this time the detection and diagnosis model is still done manually, so it was not effective and efficient. The inspection data obtained using the information system becomes more complete and faster. Data obtained with information systems can be seen anywhere and anytime. This study produced innovations for the detection of preeclampsia in pregnant women using a rule-based system information system. This study uses the Quasy experimental posttest-only design. The subjects of this study were 66 pregnant women. Data collection was carried out using questionnaires and checklists. The results showed that early detection of preeclampsia using a rule-based system information system could improve the completeness of data on pregnant women up to 35.66%, and speed up the detection time of preeclampsia up to 35.60%. This system also has an effectivenessvalue 84.8%. © 2019 IOP Publishing Ltd. All rights reserved.

关键词： Decision making

Crouzeix’s Conjecture and Related Problems

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arXiv 2020年

作者： Bickel, Kelly Gorkin, Pamela Greenbaum, Anne Ransford, Thomas Schwenninger, Felix Wegert, Elias Department of Mathematics Bucknell University LewisburgPA17837 United States Department of Mathematics Bucknell University LewisburgPA17837 United States Department of Applied Mathematics University of Washington Département de mathématiques et de statistique Université Laval QuébecQCG1V 0A6 Canada Department of Mathematics Universität Hamburg Department of Applied Mathematics University of Twente Netherlands Department of Mathematics and Computer Science Technische Universität Bergakademie Freiberg Division of Mathematical Sciences National Science Foundation United States NSERC and the Canada Research Chairs program

In this paper, we establish several results related to Crouzeixs conjecture. We show that the conjecture holds for contractions with eigenvalues that are sufficiently well-separated. This separation is measured by the so-called separation constant, which is defined in terms of the pseudohyperbolic metric. Moreover, we study general properties of related extremal functions and associated vectors. Throughout, compressions of the shift serve as illustrating examples which also allow for refined *** Codes 47A25, 47A12, 15A60, 47A20, 30J10 Copyright © 2020, The Authors. All rights reserved.

关键词： Eigenvalues and eigenfunctions

On the Lagrangian-Eulerian Coupling in the Immersed Finite Element/Difference Method

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arXiv 2021年

作者： Lee, Jae H. Griffith, Boyce E. Department of Mathematics University of North Carolina Chapel HillNC United States Department of Mechanical Engineering Johns Hopkins University BaltimoreMD United States Institute for Computational Medicine Johns Hopkins University BaltimoreMD United States Departments of Mathematics Applied Physical Sciences and Biomedical Engineering University of North Carolina Chapel HillNC United States Carolina Center for Interdisciplinary Applied Mathematics University of North Carolina Chapel HillNC United States Computational Medicine Program University of North Carolina School of Medicine Chapel HillNC United States McAllister Heart Institute University of North Carolina School of Medicine Chapel HillNC United States

The immersed boundary (IB) method is a non-body conforming approach to fluid-structure interaction (FSI) that uses an Eulerian description of the momentum, viscosity, and incompressibility of a coupled fluid-structure system and a Lagrangian description of the deformations, stresses, and resultant forces of the immersed structure. Integral transforms with Dirac delta function kernels couple the Eulerian and Lagrangian variables, and in practice, discretizations of these integral transforms use regularized delta function kernels. Many different kernel functions have been proposed, but prior numerical work investigating the impact of the choice of kernel function on the accuracy of the methodology has often been limited to simplified test cases or Stokes flow conditions that may not reflect the method’s performance in applications, particularly at intermediate-to-high Reynolds numbers, or under different loading conditions. This work systematically studies the effect of the choice of regularized delta function in several fluid-structure interaction benchmark tests using the immersed finite element/difference (IFED) method, which is an extension of the IB method that uses a finite element structural discretizations combined with a Cartesian grid finite difference method for the incompressible Navier-Stokes equations. Whereas the conventional IB method spreads forces from the nodes of the structural mesh and interpolates velocities to those nodes, the IFED formulation evaluates the regularized delta function on a collection of interaction points that can be chosen to be denser than the nodes of the Lagrangian mesh. This opens the possibility of using structural discretizations with wide node spacings that would produce gaps in the Eulerian force in nodally coupled schemes (e.g., if the node spacing is comparable to or broader than the support of the regularized delta function). Earlier work with this methodology suggested that such coarse structural meshes can yield imp

关键词： Fluid structure interaction

Realistic-science, technology, engineering, and mathematics assisted by google classroom as a learning innovation in the new normal era to improve statistical thinking skill

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Journal of Physics: Conference Series 2021年第4期1918卷

作者： A S Ardiansyah N A Novita H Zhintya D Kurnianto Mathematics Education Study Program Universitas Negeri Semarang Applied Statistics and Computation Study Program Universitas Negeri Semarang

Based on government policies regarding the implementation of learning from home, it is necessary the learning innovation to continue learning in the new normal era by utilizing existing technological advances. In this digital era, statistics thinking is important because it is needed to be able to interpret and understand and make good decisions from the statistical data obtained. From these problems, one of the innovations that can be done is by implementing Realistic mathematics Education integrated Science, Technology, Engineering, and mathematics assisted by Google Classroom (R-STEM-GC). This paper aims to determine the effect of R-STEM-GC learning on students' statistical thinking skills. This paper uses literature review method research that identifies, assesses, and interprets all findings on a research topic to answer existing research questions. It can concluded that realistic learning was more effective in terms of students' mathematical reasoning and communication than conventional learning; learning with the application of STEM can improve students' problem solving abilities compared to conventional learning; and the use of google classrooms that can improve communication skills. From the results of this analysis, the application of R-STEM-GC learning can be an innovative solution in improving students' statistical thinking skills in new normal era.

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Historical Changes and Reasons for Model Differences in Anthropogenic Aerosol Forcing in CMIP6

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Geophysical Research Letters 2023年第15期50卷 e2023GL104848-e2023GL104848页

作者： Fiedler, Stephanie van Noije, Twan Smith, Christopher J. Boucher, Olivier Dufresne, Jean-Louis Kirkevåg, Alf Olivié, Dirk Pinto, Rovina Reerink, Thomas Sima, Adriana Schulz, Michael GEOMAR Helmholtz Centre for Ocean Research Kiel Kiel Germany Faculty of Mathematics and Natural Sciences Christian-Albrechts-University of Kiel Kiel Germany Royal Netherlands Meteorological Institute De Bilt Netherlands Priestley International Centre for Climate University of Leeds Leeds United Kingdom Energy Climate and Environment Program International Institute for Applied Systems Analysis Laxenburg Austria Institut Pierre-Simon Laplace Sorbonne Université / CNRS Paris France Sorbonne Université/CNRS/École Normale Supérieure/École Polytechnique Paris France Norwegian Meteorological Institute Oslo Norway University of Cologne Institute of Geophysics and Meteorology Cologne Germany

The Radiative Forcing Model Intercomparison Project (RFMIP) allows estimates of effective radiative forcing (ERF) in the Coupled Model Intercomparison Project phase six (CMIP6). We analyze the RFMIP output, including the new experiments from models that use the same parameterization for anthropogenic aerosols (RFMIP-SpAer), to characterize and better understand model differences in aerosol ERF. We find little changes in the aerosol ERF for 1970–2014 in the CMIP6 multi-model mean, which implies greenhouse gases primarily explain the positive trend in the total anthropogenic ERF. Cloud-mediated effects dominate the present-day aerosol ERF in most models. The results highlight a regional increase in marine cloudiness due to aerosols, despite suppressed cloud lifetime effects in that RFMIP-SpAer experiment. Negative cloud-mediated effects mask positive direct effects in many models, which arise from strong anthropogenic aerosol absorption. The findings suggest opportunities to better constrain simulated ERF by revisiting the optical properties and long-range transport of aerosols. © 2023 The Authors.

关键词： Climate models

Ina sua: The traditional Food Fermentation from Teon Nila Serua, Central of Maluku, Indonesia

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Journal of Ethnic Foods 2020年第1期7卷 1页

作者： Persulessy, Cassandra Betsy Kusdiyantini, Endang Ferniah, Rejeki Siti Agustini, Tri Winarni Budiharjo, Anto Department of Biology Faculty of Science and Mathematics Diponegoro University Jl. Prof. Sudharto SH Semarang 50275 Indonesia Biotechnology Study Program Faculty of Science and Mathematics Diponegoro University Jl. Prof. Sudharto SH Semarang 50275 Indonesia Department of Fisheries Fisheries and Marine Science Faculty Diponegoro University Jl. Prof. Sudharto SH Semarang 50275 Indonesia Molecular and Applied Microbiology Laboratory Central Laboratory of Research and Service Diponegoro University Jl. Prof. Sudharto SH Semarang 50275 Indonesia

Traditional fermented food as a special delicacy is one of the elements of culinary diversity found in many regions of Indonesia. This type of food is closely related to the customs and surrounding environment, displaying the characteristics of each region and ethnicity. Maluku is one of the regions located in Eastern Indonesia. Ina sua is a simple and traditional fermented food made from fish using salt as a basic ingredient, commonly eaten at a variety of traditional events in Central Maluku, especially in Teon Nila Serua (TNS). Ina sua is made to be stored and consumed during a time when fish is not available and when there are community activities such as birthdays and traditional events. In making Ina sua, fish are salted with salt granules and stored for a certain time. Therefore, this food is famous for its unique taste produced by the fermentation component. In this article, the origin of Ina sua, its method of preparation, and the scientific perspectives surrounding it are discussed. © 2020 The Author(s).

关键词： Central of Mollucas Ina Sua Traditional fish food fermentation

Threshold and decay properties of transient isolated turbulent band in plane Couette flow

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applied mathematics and Mechanics(English Edition) 2019年第10期40卷 1449-1456页

作者： Jianzhou LU Jianjun TAO Weitao ZHOU Xiangming XIONG CAPT-HEDPS SKLTCS Collaborative Innovation Center of IFSA Department of Mechanics and Engineering Science College of Engineering Peking University Beijing 100871 China The Program in Applied and Computational Mathematics Princeton University Princeton NJ 08544 U. S.A.

By direct numerical simulations of the plane Couette flow (PCF) in a large computational domain, it is shown that an isolated turbulent band decays monotonically at low Reynolds numbers but experiences transient growth before the eventual relaminarization at moderate Reynolds numbers. The lower bound Reynolds number of the transient-growth regime is determined as 286. The width, length, and tilt angle of the iso- lated band structure are defined based on the disturbance kinetic energy in the mid-plane, and the geometric characteristics of the band can be described with a tilted rectangle. It is illustrated that before its eventual fragmentation, the isolated turbulent band decays in a style of longitudinal contraction, where the center, width, and tilt angle of the band keep almost constant but the band length contracts with a statistically constant velocity.

关键词： plane Couette flow (PCF) subcritical transition turbulent band

Neural network representation of electronic structure from ab initio molecular dynamics

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arXiv 2020年

作者： Gu, Qiangqiang Zhang, Linfeng Feng, Ji International Center for Quantum Materials School of Physics Peking University Beijing100871 China Department of Mathematics and Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States Collaborative Innovation Center of Quantum Matter Beijing100871 China

Despite their rich information content, electronic structure data amassed at high volumes in ab initio molecular dynamics simulations are generally under-utilized. We introduce a transferable high-fidelity neural network representation of such data in the form of tight-binding Hamiltonians for crystalline materials. This predictive representation of ab initio electronic structure, combined with machine-learning boosted molecular dynamics, enables efficient and accurate electronic evolution and sampling. When applied to a one-dimension charge-density wave material, carbyne, we are able to compute the spectral function and optical conductivity in the canonical ensemble. The spectral functions evaluated during soliton-antisoliton pair annihilation process reveal significant renormalization of low-energy edge modes due to retarded electron-lattice coupling beyond the Born-Oppenheimer limit. The availability of an efficient and reusable surrogate model for the electronic structure dynamical system will enable calculating many interesting physical properties, paving way to previously inaccessible or challenging avenues in materials modeling. © 2020, CC-BY.

关键词： Electronic structure