1,082 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
Protocol Requirements for Self-organizing Artifacts: Towards an Ambient Intelligence
We discuss which properties common-use artifacts should have to collaborate
without human intervention. We conceive how devices, such as mobile phones,
PDAs, and home appliances, could be seamlessly integrated to provide an
"ambient intelligence" that responds to the user's desires without requiring
explicit programming or commands. While the hardware and software technology to
build such systems already exists, as yet there is no standard protocol that
can learn new meanings. We propose the first steps in the development of such a
protocol, which would need to be adaptive, extensible, and open to the
community, while promoting self-organization. We argue that devices,
interacting through "game-like" moves, can learn to agree about how to
communicate, with whom to cooperate, and how to delegate and coordinate
specialized tasks. Thus, they may evolve a distributed cognition or collective
intelligence capable of tackling complex tasks.Comment: To be presented at 5th International Conference on Complex System
Swarm-Oscillators
Nonlinear coupling between inter- and intra-element dynamics appears as a
collective behaviour of elements. The elements in this paper denote symptoms
such as a bacterium having an internal network of genes and proteins, a
reactive droplet, a neuron in networks, etc. In order to elucidate the
capability of such systems, a simple and reasonable model is derived. This
model exhibits the rich patterns of systems such as cell membrane, cell fusion,
cell growing, cell division, firework, branch, and clustered clusters
(self-organized hierarchical structure, modular network). This model is
extremely simple yet powerful; therefore, it is expected to impact several
disciplines.Comment: 9 pages, 4 figure
Flight Gate Assignment with a Quantum Annealer
Optimal flight gate assignment is a highly relevant optimization problem from
airport management. Among others, an important goal is the minimization of the
total transit time of the passengers. The corresponding objective function is
quadratic in the binary decision variables encoding the flight-to-gate
assignment. Hence, it is a quadratic assignment problem being hard to solve in
general. In this work we investigate the solvability of this problem with a
D-Wave quantum annealer. These machines are optimizers for quadratic
unconstrained optimization problems (QUBO). Therefore the flight gate
assignment problem seems to be well suited for these machines. We use real
world data from a mid-sized German airport as well as simulation based data to
extract typical instances small enough to be amenable to the D-Wave machine. In
order to mitigate precision problems, we employ bin packing on the passenger
numbers to reduce the precision requirements of the extracted instances. We
find that, for the instances we investigated, the bin packing has little effect
on the solution quality. Hence, we were able to solve small problem instances
extracted from real data with the D-Wave 2000Q quantum annealer.Comment: Updated figure
Cohesive motion in one-dimensional flocking
A one-dimensional rule-based model for flocking, that combines velocity
alignment and long-range centering interactions, is presented and studied. The
induced cohesion in the collective motion of the self-propelled agents leads to
a unique group behaviour that contrasts with previous studies. Our results show
that the largest cluster of particles, in the condensed states, develops a mean
velocity slower than the preferred one in the absence of noise. For strong
noise, the system also develops a non-vanishing mean velocity, alternating its
direction of motion stochastically. This allows us to address the directional
switching phenomenon. The effects of different sources of stochasticity on the
system are also discussed.Comment: 24 pages, 11 figure
Ant colony optimization with immigrants schemes in dynamic environments
This is the post-print version of this article. The official published version can be accessed from the link below - Copyright @ 2010 Springer-VerlagIn recent years, there has been a growing interest in addressing dynamic optimization problems (DOPs) using evolutionary algorithms (EAs). Several approaches have been developed for EAs to increase the diversity of the population and enhance the performance of the algorithm for DOPs. Among these approaches, immigrants schemes have been found beneficial for EAs for DOPs. In this paper, random, elitismbased, and hybrid immigrants schemes are applied to ant colony optimization (ACO) for the dynamic travelling salesman problem (DTSP). The experimental results show that random immigrants are beneficial for ACO in fast changing environments, whereas elitism-based immigrants are beneficial for ACO in slowly changing environments. The ACO algorithm with hybrid immigrants scheme combines the merits of the random and elitism-based immigrants schemes. Moreover, the results show that the proposed algorithms outperform compared approaches in almost all dynamic test cases and that immigrant schemes efficiently improve the performance of ACO algorithms in DTSP.This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) of UK under Grant EP/E060722/1
Analyzing Trails in Complex Networks
Even more interesting than the intricate organization of complex networks are
the dynamical behavior of systems which such structures underly. Among the many
types of dynamics, one particularly interesting category involves the evolution
of trails left by moving agents progressing through random walks and dilating
processes in a complex network. The emergence of trails is present in many
dynamical process, such as pedestrian traffic, information flow and metabolic
pathways. Important problems related with trails include the reconstruction of
the trail and the identification of its source, when complete knowledge of the
trail is missing. In addition, the following of trails in multi-agent systems
represent a particularly interesting situation related to pedestrian dynamics
and swarming intelligence. The present work addresses these three issues while
taking into account permanent and transient marks left in the visited nodes.
Different topologies are considered for trail reconstruction and trail source
identification, including four complex networks models and four real networks,
namely the Internet, the US airlines network, an email network and the
scientific collaboration network of complex network researchers. Our results
show that the topology of the network influence in trail reconstruction, source
identification and agent dynamics.Comment: 10 pages, 16 figures. A working manuscript, comments and criticisms
welcome
Testing demand responsive shared transport services via agent-based simulations
Demand Responsive Shared Transport DRST services take advantage of
Information and Communication Technologies ICT, to provide on demand transport
services booking in real time a ride on a shared vehicle. In this paper, an
agent-based model ABM is presented to test different the feasibility of
different service configurations in a real context. First results show the
impact of route choice strategy on the system performance
Memory-based immigrants for ant colony optimization in changing environments
Copyright @ 2011 SpringerAnt colony optimization (ACO) algorithms have proved that they can adapt to dynamic optimization problems (DOPs) when they are enhanced to maintain diversity. DOPs are important due to their similarities to many real-world applications. Several approaches have been integrated with ACO to improve their performance in DOPs, where memory-based approaches and immigrants schemes have shown good results on different variations of the dynamic travelling salesman problem (DTSP). In this paper, we consider a novel variation of DTSP where traffic jams occur in a cyclic pattern. This means that old environments will re-appear in the future. A hybrid method that combines memory and immigrants schemes is proposed into ACO to address this kind of DTSPs. The memory-based approach is useful to directly move the population to promising areas in the new environment by using solutions stored in the memory. The immigrants scheme is useful to maintain the diversity within the population. The experimental results based on different test cases of the DTSP show that the memory based immigrants scheme enhances the performance of ACO in cyclic dynamic environments.This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) of UK under Grant EP/E060722/2
Para investigar a la vejez: desafíos y alternativas durante el trabajo de campo
El presente ensayo ofrece una reflexión metodológica sobre las dificultades enfrentadas durante el trabajo de campo cuando los informantes clave son individuos con discapacidades biológicas o mentales, como es el caso de los ancianos. La intención es abrir el debate metodológico acerca de cómo se hace investigación cualitativa en el campo del envejecimiento. La primera parte se centra en el fenómeno de la exclusión de ancianos con mayor grado de deterioro, al seleccionar a los informantes. La segunda parte describe algunas situaciones por las que se dificulta la entrevista con este tipo de ancianos, lo que origina la pérdida de informantes. Por último, se alude a las condiciones de discapacidad biológica o mental que afectan el desarrollo de una entrevista en los cánones tradicionales prescritos en los textos metodológicos y las alternativas para enfrentarlas
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