Dynamic Characteristics Of Multiscale Interaction System

In recent years,multiscale problem has attracted more and more researchers' attention due to its broad research space and rich scientific connotation,and has become a very challenging research topic.Multiscale phenomena have been widely studied in many fields such as natural science,biological science,ecosystem and environment,graphics processing,human vision,meteorological science,modern engineering industry and social science.Under the current mature experimental environment and science and technology,multiscale phenomena have been widely used in macroscopic matter,mesoscopic matter and microscopic matter,and in the interdiscipl inary fields such as physics,material science,chemistry,biology and even life science and so forth.As one of the important branches of complex systems,multiscale science is an interdisciplinary science that studies the coupling phenomenon of different spatial or temporal scales.It is a hot topic in the field of soft matters to study the non-equilibrium dynamics.In particular,the origin of dynamic ordered structure of multiscale interaction particle system provides a valuable guidance for revealing the active origin of biological system.In the first chapter,multi-scale phenomena and multiscale interacting particle systems are described.Multiscale science and its applications in various fields are also included here.In the second chapter,we review the studying progresses on the dynamics of competing repulsion and attraction particle systems are reviewed.Firstly,the charged particle systems with competing repulsion and attraction interactions are described.Secondly,the magnetized particle systems with competing repulsion and attraction interaction are described.Then,using Langevin molecular dynamics,we study the sliding friction of a monolayer competing repulsive magnetic dipole + attractive Lennard-Jones interaction particle system on the substrate with disordered pinning centers.It is found that under the conditions of low temperature,weak substrate pinning strength,weak attraction and strong repulsion interaction between particles,super lubrication will occur.Friction originates from the movement of particles in the channels between different substrate pinning centers.Accompanying with the occurrence of hyper lubrication,island structures with clear boundaries appear in the microscopic particle structure.In addition,we investigate the directional mode-locking of a monolayer competing repulsive magnetic dipole + attractive Lennard-Jones interaction particle system on the substrate with periodic pinning centers.It is found that the directional mode-locking phenomenon occurs in some symmetrical pinning potential directions above the depinning at low temperature and with certain repulsive interaction intensities.This is different from the strict mode-locking of the particle system with single scale repulsion interaction.Some particles are found to deviate from the mode-locking direction.Finally,we study the collective depinning of monolayer magnetized particle systems with competing repulsive dipole + Mie potential with different attraction index n.We find that with the increasing n,a peak effect arises in the the critical pinning force at n=6;When n<6,obvious living island structures appear above the depinning,and their formation is a non-equilibrium process of rapid fusion growth;When n>6,the living island structures disappear;As n is increased further,elastic near-crystalline and even crystalline phases will appear above the depinning.With an increase in the repulsive interaction intensity between particles,the peak of critical pinning force will move in the direction that the repulsive interaction intensity decreases until it disappears,at which time the attraction term exponent n=6.With an increase in the attraction interaction between particles,the critical pinning force is basically unchanged,while when n=6,the critical pinning force tends to decrease.In chapter 3,we firstly describe the purely repulsive interaction particle systems with multiple scales.Then,using Langevin molecular dynamics,we investigate the depinning dynamics of monolayer multiscale purely repulsive particle systems on the substrate with disordered pinning centers.The interactions between particles are supposed to be composed of double-scale purely repulsive interactions with the types of the long-range Coulomb potential + the medium-range magnetic dipole potential,the medium-range magnetic dipole potential + the short-range screening Coulomb potential,and the short-range screening Coulomb potential + the short-range repulsive nuclei.It is found that the double-scale purely repulsive interaction systems with similar force ranges(i.e.the double-scale purely repulsive interaction system composed of short-range repulsive nuclei and short-range screening Coulomb potential)are more prone to order motion above the depinning.Through comparing the double-scale purely repulsive interaction system with the single-scale repulsive interaction system,we find that the double-scale purely repulsive interaction system with similar force ranges(i.e.,the double-scale purely repulsive interaction system composed of short-range repulsive nuclei + short-range screening Coulomb potential)shows more obvious order than that of the single scale repulsive interaction system.The presented results will be helpful for revealing the formation mechanism of dynamic order,and for providing valuable guidance for controlling and adjusting the dynamic order as well as continuous separation of different species of mesoscopic particles and biological cells.