scholarly journals Swirlonic state of active matter

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Nikolai V. Brilliantov ◽  
Hajar Abutuqayqah ◽  
Ivan Yu Tyukin ◽  
Sergey A. Matveev
Keyword(s):  
Driving Forces ◽  
Center Of Mass ◽  
Active Matter ◽  
Molecular Systems ◽  
Solid States ◽  
Active Particles ◽  
Unusual Phenomenon ◽  
Viscous Media ◽  
Common Center ◽  
Simulation Results

Abstract We report a novel state of active matter—a swirlonic state. It is comprised of swirlons, formed by groups of active particles orbiting their common center of mass. These quasi-particles demonstrate a surprising behavior: In response to an external load they move with a constant velocity proportional to the applied force, just as objects in viscous media. The swirlons attract each other and coalesce forming a larger, joint swirlon. The coalescence is extremely slow, decelerating process, resulting in a rarified state of immobile quasi-particles. In addition to the swirlonic state, we observe gaseous, liquid and solid states, depending on the inter-particle and self-driving forces. Interestingly, in contrast to molecular systems, liquid and gaseous states of active matter do not coexist. We explain this unusual phenomenon by the lack of fast particles in active matter. We perform extensive numerical simulations and theoretical analysis. The predictions of the theory agree qualitatively and quantitatively with the simulation results.

Study on the Steering Performance of Dual-Motor Drive Track Bulldozer

2013 ◽  
Vol 427-429 ◽  
pp. 133-136
Author(s):  
Qiang Song ◽  
Pu Zeng
Keyword(s):  
Simulation Model ◽  
Dynamic Characteristics ◽  
Driving Force ◽  
Driving Forces ◽  
Small Radius ◽  
Motor Drive ◽  
Matlab Simulink ◽  
Simulation Results ◽  
Two Sides

The driving theory and the dynamic characteristics of small radius steering, medium radius steering and big radius steering is analyzed, and the simulation model is established under Matlab/Simulink. Then the track bulldozers steering performance of the three sheerings is simulated. The results show that, at different steering modes, the running states of the two sides driving motors are not the same, and the track driving forces of the two sides vary widely. The track driving force is great in the small radius steering model, while small in the medium and big radius steering models. The simulation results lay the foundation for dual-motor drive track bulldozers steering performance matching.

Active Particle Diffusion in Convection Roll Arrays

2021 ◽  
Author(s):  
Pulak Kumar Ghosh ◽  
Fabio Marchesoni ◽  
Yunyun Li ◽  
Franco Nori
Keyword(s):  
Active Particle ◽  
Particle Diffusion ◽  
Active Matter ◽  
Active Particles ◽  
Convection Roll ◽  
Small Scales

Undesired advection effects are unavoidable in most nano-technological applications involving active matter. However, it is conceivable to govern the transport of active particles at the small scales by suitably tuning...

scholarly journals Comparison of turbulence in HII regions and molecular clouds

1991 ◽  
Vol 147 ◽  
pp. 476-479
Author(s):  
C. R. O'Dell
Keyword(s):  
Molecular Clouds ◽  
Center Of Mass ◽  
Hii Regions ◽  
Emission Lines ◽  
General Increase ◽  
Hii Region ◽  
Velocity Relation ◽  
Common Center ◽  
The One ◽  
Kolmogorov Theory

Both the HII Regions and the Molecular Clouds show broadening of their emission lines beyond that expected from thermal motion and this is ascribed to turbulence. Turbulence in molecular clouds generally agrees with a model where the velocity of motion is determined by the Alfv én velocity.Turbulence in Galactic HII Regions and Giant Extragalactic HII Regions can also be studied by the width of the emission lines. The magnitude of the turbulent velocities in these regions are characteristically about 10 km/s. There is a general increase in turbulent velocity with the size of the HII Region, and this relation is close to but different from the one third power dependence expected from the most naive application of Kolmogorov theory. When a detailed study is conducted of each Galactic HII Region by means of the structure function, one finds that there is not agreement with Kolmogorov theory.The Size-Turbulent versus Velocity relation for Galactic HII Regions differs slightly from the better defined velocity relation for Giant Extragalactic HII Regions. This difference is probably due to the fact that the larger extragalactic objects are probably complexes of multiple individual HII Regions. There is no evidence that broadening of extragalactic HII Regions is due to motion about a common center of mass.

scholarly journals Oscillating collective motion of active rotors in confinement

2020 ◽  
Vol 117 (22) ◽  
pp. 11901-11907 ◽  
Author(s):  
Peng Liu ◽  
Hongwei Zhu ◽  
Ying Zeng ◽  
Guangle Du ◽  
Luhui Ning ◽  
...  
Keyword(s):  
Collective Behavior ◽  
Collective Motion ◽  
Dynamic Structure ◽  
Packing Fraction ◽  
Frictional Stress ◽  
Active Matter ◽  
Active Particles ◽  
Particle Level ◽  
Inhomogeneous Density ◽  
Oscillation Properties

Due to its inherent out-of-equilibrium nature, active matter in confinement may exhibit collective behavior absent in unconfined systems. Extensive studies have indicated that hydrodynamic or steric interactions between active particles and boundary play an important role in the emergence of collective behavior. However, besides introducing external couplings at the single-particle level, the confinement also induces an inhomogeneous density distribution due to particle-position correlations, whose effect on collective behavior remains unclear. Here, we investigate this effect in a minimal chiral active matter composed of self-spinning rotors through simulation, experiment, and theory. We find that the density inhomogeneity leads to a position-dependent frictional stress that results from interrotor friction and couples the spin to the translation of the particles, which can then drive a striking spatially oscillating collective motion of the chiral active matter along the confinement boundary. Moreover, depending on the oscillation properties, the collective behavior has three different modes as the packing fraction varies. The structural origins of the transitions between the different modes are well identified by the percolation of solid-like regions or the occurrence of defect-induced particle rearrangement. Our results thus show that the confinement-induced inhomogeneity, dynamic structure, and compressibility have significant influences on collective behavior of active matter and should be properly taken into account.

scholarly journals A Dynamic Territorializing Approach for Multiagent Task Allocation

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Mohammad Islam ◽  
Mehdi Dadvar ◽  
Hassan Zargarzadeh
Keyword(s):  
Task Allocation ◽  
Center Of Mass ◽  
Theoretic Analysis ◽  
Game Theoretic Analysis ◽  
Alternative Approach ◽  
Game Theoretic ◽  
Simulation Results ◽  
Reasoning Mechanism

In this paper, we propose a dynamic territorializing approach for the problem of distributing tasks among a group of robots. We consider the scenario in which a task comprises two subtasks—detection and completion; two complementary teams of agents, hunters and gatherers, are assigned for the subtasks. Hunters are assigned with the task of exploring the environment, i.e., detection, whereas gatherers are assigned with the latter subtask. To minimize the workload among the gatherers, the proposed algorithm utilizes the center of mass of the known targets to form territories among the gatherers. The concept of center of mass has been adopted because it simplifies the task of territorial optimization and allows the system to dynamically adapt to changes in the environment by adjusting the assigned partitions as more targets are discovered. In addition, we present a game-theoretic analysis to justify the agents’ reasoning mechanism to stay within their territory while completing the tasks. Moreover, simulation results are presented to analyze the performance of the proposed algorithm. First, we investigate how the performance of the proposed algorithm varies as the frequency of territorializing is varied. Then, we examine how the density of the tasks affects the performance of the algorithm. Finally, the effectiveness of the proposed algorithm is verified by comparing its performance against an alternative approach.

scholarly journals Investigating the Influence of Shaft Balance Point on Clubhead Speed: A Simulation Study

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 156
Author(s):  
William McNally ◽  
John McPhee
Keyword(s):  
Total Mass ◽  
Center Of Mass ◽  
Golf Club ◽  
Physical Interaction ◽  
Balance Point ◽  
Mass Distributions ◽  
Biomechanical Models ◽  
Significant Difference ◽  
The Mean ◽  
Simulation Results

In this study, a dynamic golfer model was used to investigate the influence of the golf shaft’s balance point (i.e., center of mass) on the generation of clubhead speed. Three hypothetical shaft designs having different mass distributions, but the same total mass and stiffness, were proposed. The golfer model was then stochastically optimized 100 times using each shaft. A statistically significant difference was found between the mean clubhead speeds at impact (p < 0.001), where the clubhead speed increased as the balance point moved closer to the grip. When comparing the two shafts with the largest difference in balance point, a 1.6% increase in mean clubhead speed was observed for a change in balance point of 18.8 cm. The simulation results have implications for shaft design and demonstrate the usefulness of biomechanical models for capturing the complex physical interaction between the golfer and golf club.

Dry Aligning Dilute Active Matter

2020 ◽  
Vol 11 (1) ◽  
pp. 189-212 ◽  
Author(s):  
Hugues Chaté
Keyword(s):  
Long Range ◽  
Collective Motion ◽  
Local Level ◽  
Orientational Order ◽  
Two Dimensions ◽  
Active Matter ◽  
Long Range Correlations ◽  
Active Particles ◽  
Growing Domain

Active matter physics is about systems in which energy is dissipated at some local level to produce work. This is a generic situation, particularly in the living world but not only. What is at stake is the understanding of the fascinating, sometimes counterintuitive, emerging phenomena observed, from collective motion in animal groups to in vitro dynamical self-organization of motor proteins and biofilaments. Dry aligning dilute active matter (DADAM) is a corner of the multidimensional, fast-growing domain of active matter that has both historical and theoretical importance for the entire field. This restrictive setting only involves self-propulsion/activity, alignment, and noise, yet unexpected collective properties can emerge from it. This review provides a personal but synthetic and coherent overview of DADAM, focusing on the collective-level phenomenology of simple active particle models representing basic classes of systems and on the solutions of the continuous hydrodynamic theories that can be derived from them. The obvious fact that orientational order is advected by the aligning active particles at play is shown to be at the root of the most striking properties of DADAM systems: ( a) direct transitions to orientational order are not observed; ( b) instead generic phase separation occurs with a coexistence phase involving inhomogeneous nonlinear structures; ( c) orientational order, which can be long range even in two dimensions, is accompanied by long-range correlations and anomalous fluctuations; ( d) defects are not point-like, topologically bound objects.

Energy Harvesting From Bike Using Linear DC Motor

2010 ◽  
Author(s):  
Reza Sabzehgar ◽  
Siamak Arzanpour
Keyword(s):  
Energy Harvesting ◽  
Vibration Analysis ◽  
Center Of Mass ◽  
Dc Motor ◽  
Linear Motor ◽  
Electrical Parameters ◽  
Power Simulation ◽  
Linear Dc Motor ◽  
Simulation Results

This paper investigates the application of a proposed energy harvesting mechanism to convert the vibrations in a bicycle tire to electricity. For this setting all tire spokes have been removed and two spring-damper links and one linear DC motor are used instead. The vibration analysis of the tire’s center of mass caused by bicycle motion is obtained using trigonometric relations. Moreover, the regenerated power by the linear motor is obtained analytically. This model together with the motion of the center of the mass of the tire are used to estimate the harvested power. The mechanical and electrical parameters are also optimized to harvest the maximize the power. Simulation results show the efficiency of proposed energy harvesting mechanism.

OPTIMAL STANDING LONG JUMP SIMULATION FROM DIFFERENT STARTING POSTURES

2005 ◽  
Vol 05 (02) ◽  
pp. 203-215 ◽  
Author(s):  
KUANG-YOU B. CHENG ◽  
WEN-CHIEN CHEN
Keyword(s):  
Center Of Mass ◽  
Joint Torque ◽  
Horizontal Distance ◽  
Human Body Model ◽  
Body Model ◽  
Standing Long Jump ◽  
Jump Distance ◽  
Torque Generation ◽  
Long Jump ◽  
Simulation Results

A planar 4-segment human body model is used to simulate and study the effects of starting posture on standing long jumping performance. The model consists of frictionless hinge joints and is driven by joint torque actuators. The four segments represent feet, shanks, thighs, and trunk with head and arms. Movement simulations start from three different postures: high squat, squat, and low squat. The control variables are the joint torque activation levels and takeoff time. The objective function is the maximum horizontal distance from the toe point at takeoff to the center of mass (c.m.) position at landing. Optimal simulation results agree reasonably well with measurements. Different from previous high jump simulation study, slight dependence of initial posture on jump distance is found. Longer jump distance from a higher initial posture is probably due to greater range of countermovement that results in larger extension joint torque generation.

scholarly journals Analysis of the umbrella-type reflector opening process on a stand with an active gravity compensation system

2021 ◽  
Vol 5 (4) ◽  
pp. 208-216
Author(s):  
A. V. Ivanov ◽  
S. A. Zommer
Keyword(s):  
3D Model ◽  
Computational Analysis ◽  
Driving Forces ◽  
Center Of Mass ◽  
Compensation System ◽  
Gravity Compensation ◽  
Suspension Point ◽  
Axis Of Rotation ◽  
Ground Conditions ◽  
Suspension Cable

During the verification of the functioning of the transformed structures in ground conditions, it is necessary to minimize the effect of gravity in order to exclude the occurrence of additional loads on the hinge assemblies and opening mechanisms. To perform this task, when testing a transformable umbrella-type reflector, stands with an active gravity compensation system are used, in which the gravity compensation force is applied to each spoke of the reflector. However, when compensating for the gravity spokes of the reflector, the fixing point of the suspension cable does not coincide with the center of mass of the spoke, which leads to the appearance of additional moments of forces acting on the suspended structure. Therefore, as an object of research, a part of the reflector was considered, consisting of a spoke, with cords of a formforming structure attached to it and a mesh. A 3D model has been developed, using which the positions of the center of mass of the structure under consideration were determined in the key phases of the reflector opening. A computational analysis of the driving forces and moments acting on the structure in the process of disclosure is carried out. The degree of influence of the suspension point position on the inaccuracy of gravity compensation has been established. The results of the analysis presented in the article can be used as initial data for the development of an algorithm for the operation of an active gravity compensation system, which will be able to take into account the position of the suspension point and the center of mass of the structure relative to the axis of rotation of the spoke during the opening of the reflector, by changing the gravity compensation force.

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