computational methods in science and technology最新文献_第5页

Ergodicity of One-dimensional Oscillators with a Signum Thermostat 带sgn温控器的一维振子的遍历性

computational methods in science and technology Pub Date : 2018-01-01 DOI: 10.12921/CMST.2018.0000042

J. Sprott

引用次数: 7

From the Dynamic Lattice Liquid Algorithm to the Dedicated Parallel Computer – mDLL Machine 从动态格液算法到专用并行计算机mDLL机

computational methods in science and technology Pub Date : 2018-01-01 DOI: 10.12921/CMST.2018.0000054

Jarosław Jung, R. Kiełbik, K. Rudnicki, K. Hałagan, P. Polanowski, A. Sikorski

引用次数: 0

Qualitative Analysis of Both Hyperbolic and Non-hyperbolic Equilibria of a SIRS Model with Logistic Growth Rate of Susceptibles and Inhibitory Effect in the Infection 具有易感物Logistic增长率和感染抑制效应的SIRS模型双曲和非双曲均衡的定性分析

computational methods in science and technology Pub Date : 2018-01-01 DOI: 10.12921/CMST.2018.0000029

J. Ghosh, U. Ghosh, S. Sarkar

引用次数: 0

Using GPU Accelerators for Parallel Simulations in Material Physics 在材料物理中使用GPU加速器进行并行模拟

computational methods in science and technology Pub Date : 2018-01-01 DOI: 10.12921/cmst.2018.0000025

Mariusz Uchroński, P. Potasz, Agnieszka Szymańska-Kwiecień, M. Hruszowiec

{"title":"Using GPU Accelerators for Parallel Simulations in Material Physics","authors":"Mariusz Uchroński, P. Potasz, Agnieszka Szymańska-Kwiecień, M. Hruszowiec","doi":"10.12921/cmst.2018.0000025","DOIUrl":"https://doi.org/10.12921/cmst.2018.0000025","url":null,"abstract":"This work is focused on parallel simulation of electron-electron interactions in materials with non-trivial topological order (i.e. Chern insulators). The problem of electron-electron interaction systems can be solved by diagonalizing a many-body Hamiltonian matrix in a basis of configurations of electrons distributed among possible single particle energy levels – the configuration interaction method. The number of possible configurations exponentially increases with the number of electrons and energy levels; 12 electrons occupying 24 energy levels corresponds to the dimension of Hilbert space about 10. Solving such a problem requires effective computational methods and highly efficient optimization of the source code. The work is focused on many-body effects related to strongly interacting electrons on flat bands with non-trivial topology. Such systems are expected to be useful in study and understanding of new topological phases of matter, and in further future they can be used to design novel nanomaterials. Heterogeneous architecture based on GPU accelerators and MPI nodes will be used for improving performance and scalability in parallel solving problem of electron-electron interaction systems.","PeriodicalId":10561,"journal":{"name":"computational methods in science and technology","volume":"2 1","pages":"249-258"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84289995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Transient Heat Flow in a One-component Lennard-Jones/spline Fluid. A Non-equilibrium Molecular Dynamics Study 单组分Lennard-Jones/样条流体的瞬态热流。非平衡分子动力学研究

computational methods in science and technology Pub Date : 2017-09-30 DOI: 10.12921/CMST.2017.00000012

B. Hafskjold

{"title":"Transient Heat Flow in a One-component Lennard-Jones/spline Fluid. A Non-equilibrium Molecular Dynamics Study","authors":"B. Hafskjold","doi":"10.12921/CMST.2017.00000012","DOIUrl":"https://doi.org/10.12921/CMST.2017.00000012","url":null,"abstract":"A one-component Lennard-Jones/spline fluid at equilibrium was perturbed by a sudden change of the temperature at one of the system’s boundaries. The system’s response was determined by non-equilibrium molecular dynamics (NEMD). The results show that heat was transported by two mechanisms: (1) Heat diffusion and conduction, and (2) energy dissipation associated with the propagation of a pressure (shock) wave. These two processes occur at different time scales, which makes it possible to separate them in one single NEMD run. The system was studied in gas, liquid, and supercritical states with various forms and strengths of the thermal perturbation. Near the heat source, heat was transported according to the transient heat equation. In addition, there was a much faster heat transport, correlated with a pressure wave. This second mechanism was similar to the thermo-mechanical “piston effect” in near-critical fluids and could not be explained by the Joule-Thomson effect. For strong perturbations, the pressure wave travelled faster than the speed of sound, turning it into a shock wave. The system’s local measurable heat flux was found to be consistent with Fourier’s law near the heat source, but not in the wake of the shock. The NEMD results were, however, consistent with the Cattaneo-Vernotte model. The system was found to be in local equilibrium in the transient phase, even with very strong perturbations, except for a low-density gas. For dense systems, we did not find that the local equilibrium assumption used in classical irreversible thermodynamics is inconsistent with the Cattaneo-Vernotte model.","PeriodicalId":10561,"journal":{"name":"computational methods in science and technology","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78495143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Non-equilibrium Computer Simulations of Coupling Effects under Thermal Gradients 热梯度下耦合效应的非平衡计算机模拟

computational methods in science and technology Pub Date : 2017-09-30 DOI: 10.12921/CMST.2017.0000018

F. Bresme

引用次数: 0

Minimal Energy Dissipation Rate and Director Orientation Relative to External Dissipative Fields such as Temperature and Velocity Gradients in Nematic and Cholestric Liquid Crystals 向列型和胆甾型液晶中相对于外部耗散场(如温度和速度梯度)的最小能量耗散率和指向

computational methods in science and technology Pub Date : 2017-09-30 DOI: 10.12921/CMST.2016.0000066

S. Sarman, Yong-lei Wang, A. Laaksonen

{"title":"Minimal Energy Dissipation Rate and Director Orientation Relative to External Dissipative Fields such as Temperature and Velocity Gradients in Nematic and Cholestric Liquid Crystals","authors":"S. Sarman, Yong-lei Wang, A. Laaksonen","doi":"10.12921/CMST.2016.0000066","DOIUrl":"https://doi.org/10.12921/CMST.2016.0000066","url":null,"abstract":": The purpose of this review article is to summarize observations accumulated over the years on director alignment phenomena in nematic and cholesteric liquid crystals by molecular dynamics simulation of molecular model systems and by experiment on real systems. The main focus is on the alignment angle between the director and external dissipative ﬁelds such as velocity gradients in various ﬂow geometries and temperature gradients doing irreversible work on the system. A general observation is that the director attains an orientation relative to the ﬁeld where the energy dissipation rate is minimal in the steady state. In the case of planar elongational ﬂow, it can be proven by using symmetry arguments that the energy dissipation rate must be either maximal or minimal and simulations have shown that is minimal. In planar Couette ﬂow both simulations and experiments imply that the energy dissipation rate is minimal in the steady state. Finally, in the case of heat conduction, symmetry arguments imply that the energy dissipation rate must be either minimal or maximal and simulations and experiments indicate that it is minimal. All these observations can be explained by applying a recently proven theorem according to which the energy dissipation rate is minimal in the steady state in the linear regime at low ﬁelds.","PeriodicalId":10561,"journal":{"name":"computational methods in science and technology","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91054880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Advances in Theory and Simulation of Non-equilibrium Systems : foreword 非平衡系统的理论与模拟进展前言

computational methods in science and technology Pub Date : 2017-09-30 DOI: 10.12921/cmst.2017.0000038

K. Travis, F. Bresme

引用次数: 0

Deviations From Classical Hydrodynamic Theory in Highly Confined Planar Poiseuille Flow of a Polymer Solution 聚合物溶液高度受限平面泊泽维尔流动与经典流体力学理论的偏差

computational methods in science and technology Pub Date : 2017-09-30 DOI: 10.12921/CMST.2017.0000016

A. Menzel, P. Daivis, B. D. Todd

{"title":"Deviations From Classical Hydrodynamic Theory in Highly Confined Planar Poiseuille Flow of a Polymer Solution","authors":"A. Menzel, P. Daivis, B. D. Todd","doi":"10.12921/CMST.2017.0000016","DOIUrl":"https://doi.org/10.12921/CMST.2017.0000016","url":null,"abstract":"The behaviour of polymer solutions in highly confined geometries remains a subject of interest in rheology and fluid dynamics. In this paper, we investigate how well the classical hydrodynamic description based on the Navier-Stokes equations, Fourier's Law and Fick's Law describes the flow of a highly confined polymer solution. In particular, we examine the effects of depletion of polymer concentration at the wall-fluid interface and strain rate coupling to the heat flux. We present data from molecular dynamics simulations of a model polymer solution in explicit solvent undergoing planar Poiseuille flow for channel widths ranging from around 10 solvent atomic diameters to around 80 solvent atomic diameters. We find that the classical continuum approach works very well for channels wider than 20 solvent atomic diameters. For narrower channels, we observe deviations in the velocity, temperature and concentration profiles due to density oscillations near the walls, the polymer depletion effect, and possible weak strain rate coupling. For the narrowest channel, the wall effects extend to the centre of the channel but the underlying profiles are quite well described by the classical continuum picture. By allowing very long times of order 104 reduced time units for relaxation to the steady state and averaging over very long runs of order 105 reduced time units and 16 independent ensemble members, we are able to conclude that previously reported deviations from the classical continuum predictions (I.K. Snook, P.J. Daivis, T. Kairn, J. Physics-Condensed Matter 20, 404211 (2008)) were probably the result of insufficient equilibration time. Our results are also sufficiently accurate and precise to verify the expected quartic temperature profile predicted by classical hydrodynamic theory, with only a very small deviation which we can attribute to nonlinear coupling of the heat flux vector to the strain rate.","PeriodicalId":10561,"journal":{"name":"computational methods in science and technology","volume":"1 1","pages":"219-231"},"PeriodicalIF":0.0,"publicationDate":"2017-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78307022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Dissipative particle dynamics via molecular dynamics 耗散粒子动力学通过分子动力学

computational methods in science and technology Pub Date : 2017-09-30 DOI: 10.12921/CMST.2017.0000033

K. Travis

引用次数: 0