Scale-Free Correlations in Flocking Systems with Position-Based Interactions

Huepe, Cristián; Ferrante, Eliseo; Wenseleers, Tom; Turgut, Ali Emre

doi:10.1007/s10955-014-1114-8

Cited by 23 publications

(22 citation statements)

References 39 publications

(68 reference statements)

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“…Here, by measuring the acceleration of a focal bird in response to its neighbours, we quantified the social interaction forces in groups with sizes ranging from two to hundreds of individuals. Our measurements of short-range repulsion and long-range attraction in bird flocks agree with agent-based models [29][30][31][32][33][34]40,41,59] and empirical measurements in insects [61,69,70], fish [8,60,71], birds [44,50] and mammals [72].…”

Section: Discussionsupporting

confidence: 77%

Local interactions and their group-level consequences in flocking jackdaws

et al. 2019

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As one of nature's most striking examples of collective behaviour, bird flocks have attracted extensive research. However, we still lack an understanding of the attractive and repulsive forces that govern interactions between individuals within flocks and how these forces influence neighbours' relative positions and ultimately determine the shape of flocks. We address these issues by analysing the three-dimensional movements of wild jackdaws ( Corvus monedula ) in flocks containing 2–338 individuals. We quantify the social interaction forces in large, airborne flocks and find that these forces are highly anisotropic. The long-range attraction in the direction perpendicular to the movement direction is stronger than that along it, and the short-range repulsion is generated mainly by turning rather than changing speed. We explain this phenomenon by considering wingbeat frequency and the change in kinetic and gravitational potential energy during flight, and find that changing the direction of movement is less energetically costly than adjusting speed for birds. Furthermore, our data show that collision avoidance by turning can alter local neighbour distributions and ultimately change the group shape. Our results illustrate the macroscopic consequences of anisotropic interaction forces in bird flocks, and help to draw links between group structure, local interactions and the biophysics of animal locomotion.

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Section: Discussionsupporting

confidence: 77%

Local interactions and their group-level consequences in flocking jackdaws

et al. 2019

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“…A self-organized flocking process that starts in a disordered state (left) and eventually converges to a parallel motion state (adapted from Ferrante et al [195]). This system was shown to exhibit scale-free correlations due to the propagation of collective modes in the work by Huepe et al [194].…”

Section: Collective Mode Dynamicsmentioning

confidence: 98%

Scale invariance in natural and artificial collective systems: a review

Khaluf

Ferrante

Simoens

et al. 2017

J. R. Soc. Interface.

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Self-organized collective coordinated behaviour is an impressive phenomenon, observed in a variety of natural and artificial systems, in which coherent global structures or dynamics emerge from local interactions between individual parts. If the degree of collective integration of a system does not depend on size, its level of robustness and adaptivity is typically increased and we refer to it as scale-invariant. In this review, we first identify three main types of self-organized scale-invariant systems: scale-invariant spatial structures, scale-invariant topologies and scale-invariant dynamics. We then provide examples of scale invariance from different domains in science, describe their origins and main features and discuss potential challenges and approaches for designing and engineering artificial systems with scale-invariant properties.

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“…Such velocity alignment mechanism is at the core of the socalled Vicsek-like models [11] extensively used to study flocking patterns [1,2]. Intrinsically non-equilibrium, these patterns differ remarkably from those observed in equilibrium systems by the lack of both, Galilean invariance and momentum conservation, which allows, for instance, the emergence of long-range orientational order in two-dimensions [11][12][13] and the presence of anomalous density fluctuations [14,15].Few recent pioneering works [16][17][18][19][20][21][22][23] have challenged the wide-spread view that behind each collective motion pattern of self-propelled entities, there is a velocity alignment mechanism at work. Here, we explore the possibility of observing flocking patterns in the absence of such alignment.…”

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confidence: 99%

Large-Scale Patterns in a Minimal Cognitive Flocking Model: Incidental Leaders, Nematic Patterns, and Aggregates

2016

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We study a minimal cognitive flocking model, which assumes that the moving entities navigate using the available instantaneous visual information exclusively. The model consists of active particles, with no memory, that interact by a short-ranged, position-based, attractive force, which acts inside a vision cone (VC), and lack velocity-velocity alignment. We show that this active system can exhibit-due to the VC that breaks Newton's third law-various complex, large-scale, self-organized patterns. Depending on parameter values, we observe the emergence of aggregates or millinglike patterns, the formation of moving-locally polar-files with particles at the front of these structures acting as effective leaders, and the self-organization of particles into macroscopic nematic structures leading to long-ranged nematic order. Combining simulations and nonlinear field equations, we show that position-based active models, as the one analyzed here, represent a new class of active systems fundamentally different from other active systems, including velocity-alignment-based flocking systems. The reported results are of prime importance in the study, interpretation, and modeling of collective motion patterns in living and nonliving active systems.

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Scale-Free Correlations in Flocking Systems with Position-Based Interactions

Cited by 23 publications

References 39 publications

Local interactions and their group-level consequences in flocking jackdaws

Local interactions and their group-level consequences in flocking jackdaws

Scale invariance in natural and artificial collective systems: a review

Large-Scale Patterns in a Minimal Cognitive Flocking Model: Incidental Leaders, Nematic Patterns, and Aggregates

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