1,069 research outputs found
Logistic Constraints on 3D Termite Construction
Abstract. The building behaviour of termites has previously been modelled mathematically in two dimensions. However, physical and logistic constraints were not taken into account in these models. Here, we develop and test a three-dimensional agent-based model of this process that places realistic constraints on the diffusion of pheromones, the movement of termites, and the integrity of the architecture that they construct. The following scenarios are modelled: the use of a pheromone template in the construction of a simple royal chamber, the effect of wind on this process, and the construction of covered pathways. We consider the role of the third dimension and the effect of logistic constraints on termite behaviour and, reciprocally, the structures that they create. For instance, when agents find it difficult to reach some elevated or exterior areas of the growing structure, building proceeds at a reduced rate in these areas, ultimately influencing the range of termite-buildable architectures
Finding groups in data: Cluster analysis with ants
Wepresent in this paper a modification of Lumer and Faieta’s algorithm for data clustering. This approach
mimics the clustering behavior observed in real ant colonies. This algorithm discovers automatically
clusters in numerical data without prior knowledge of possible number of clusters. In this paper we focus
on ant-based clustering algorithms, a particular kind of a swarm intelligent system, and on the effects on
the final clustering by using during the classification differentmetrics of dissimilarity: Euclidean, Cosine,
and Gower measures. Clustering with swarm-based algorithms is emerging as an alternative to more
conventional clustering methods, such as e.g. k-means, etc. Among the many bio-inspired techniques, ant
clustering algorithms have received special attention, especially because they still require much
investigation to improve performance, stability and other key features that would make such algorithms
mature tools for data mining.
As a case study, this paper focus on the behavior of clustering procedures in those new approaches.
The proposed algorithm and its modifications are evaluated in a number of well-known benchmark
datasets. Empirical results clearly show that ant-based clustering algorithms performs well when
compared to another techniques
Coupled map gas: structure formation and dynamics of interacting motile elements with internal dynamics
A model of interacting motile chaotic elements is proposed. The chaotic
elements are distributed in space and interact with each other through
interactions depending on their positions and their internal states. As the
value of a governing parameter is changed, the model exhibits successive phase
changes with novel pattern dynamics, including spatial clustering, fusion and
fission of clusters and intermittent diffusion of elements. We explain the
manner in which the interplay between internal dynamics and interaction leads
to this behavior by employing certain quantities characterizing diffusion,
correlation, and the information cascade of synchronization. Keywords:
collective motion, coupled map system, interacting motile elementsComment: 27 pages, 12 figures; submitted to Physica
Weber’s Law-based perception and the stability of animal groups
Group living animals form aggregations and flocks that remain cohesive in
spite of internal movements of individuals. This is possible because individual
group members repeatedly adjust their position and motion in response to the
position and motion of other group members. Here we develop a theoretical
approach to address the question, what general features -- if any -- underlie
the interaction rules that mediate group stability in animals of all species?
We do so by considering how the spatial organisation of a group would change in
the complete absence of interactions. Without interactions, a group would
disperse in a way that can be easily characterised in terms of Fick's diffusion
equations. We can hence address the inverse theoretical problem of finding the
individual-level interaction responses that are required to counterbalance
diffusion and to preserve group stability. We show that an individual-level
response to neighbour densities in the form of Weber's law (a 'universal' law
describing the functioning of the sensory systems of animals of all species)
results in an 'anti-diffusion' term at the group level. On short time scales,
this anti-diffusion restores the initial group configuration in a way which is
reminiscent of methods for image deblurring in image processing. We also show
that any non-homogeneous, spatial density distribution can be preserved over
time if individual movement patterns have the form of a Weber's law response.
Weber's law describes the fundamental functioning of perceptual systems. Our
study indicates that it is also a necessary -- but not sufficient -- feature of
collective interactions in stable animal groups
Interactive robots in experimental biology
Interactive robots have the potential to revolutionise the study of social behaviour because they provide several methodological advances. In interactions with live animals, the behaviour of robots can be standardised, morphology and behaviour can be decoupled (so that different morphologies and behavioural strategies can be combined), behaviour can be manipulated in complex interaction sequences and models of behaviour can be embodied by the robot and thereby be tested. Furthermore, robots can be used as demonstrators in experiments on social learning. As we discuss here, the opportunities that robots create for new experimental approaches have far-reaching consequences for research in fields such as mate choice, cooperation, social learning, personality studies and collective behaviour. © 2011 Elsevier Ltd
Hydrodynamic fluctuations and instabilities in ordered suspensions of self-propelled particles
We construct the hydrodynamic equations for {\em suspensions} of
self-propelled particles (SPPs) with spontaneous orientational order, and make
a number of striking, testable predictions:(i) SPP suspensions with the
symmetry of a true {\em nematic} are {\em always} absolutely unstable at long
wavelengths.(ii) SPP suspensions with {\em polar}, i.e., head-tail {\em
asymmetric}, order support novel propagating modes at long wavelengths,
coupling orientation, flow, and concentration. (iii) In a wavenumber regime
accessible only in low Reynolds number systems such as bacteria, polar-ordered
suspensions are invariably convectively unstable.(iv) The variance in the
number N of particles, divided by the mean , diverges as in
polar-ordered SPP suspensions.Comment: submitted to Phys Rev Let
- …