1,721,027 research outputs found
Swarm intelligent approaches to auto-localization of nodes in static UWB networks
No full textIn this paper, we address the problem of localizing sensor nodes in a static network, given that the positions of a few of them (denoted as "beacons") are a priori known. We refer to this problem as "auto-localization." Three localization techniques are considered: the two-stage maximum-likelihood (TSML) method; the plane intersection (PI) method; and the particle swarm optimization (PSO) algorithm. While the first two techniques come from the communication-theoretic "world," the last one comes from the soft computing "world." The performance of the considered localization techniques is investigated, in a comparative way, taking into account (i) the number of beacons and (ii) the distances between beacons and nodes. Since our simulation results show that a PSO-based approach allows obtaining more accurate position estimates, in the second part of the paper we focus on this technique proposing a novel hybrid version of the PSO algorithm with improved performance. In particular, we investigate, for various population sizes, the number of iterations which are needed to achieve a given error tolerance. According to our simulation results, the hybrid PSO algorithm guarantees faster convergence at a reduced computational complexity, making it attractive for dynamic localization. In more general terms, our results show that the application of soft computing techniques to communication-theoretic problems leads to interesting research perspectives
A swarm-based approach to real-time 3D indoor localization: Experimental performance analysis
No full textIn this paper, the problem of indoor localization in wireless networks is addressed relying on a swarm-based approach. We assume to know the positions of a few number of sensor nodes, denoted as anchor nodes (ANs), and we aim at finding the position of a target node (TN) on the basis of the estimated distances between each AN and the considered TN. Since ultra wide band (UWB) technology is particularly suited for localization purposes (owing to its remarkable time resolution), we consider a network composed of UWB devices. More precisely, we carry out an experimental investigation using the PulsOn 410 ranging and communication modules (RCMs) produced by time domain. Using four of them as ANs and one of them as TN, various topologies are considered in order to evaluate the accuracy of the proposed swarm-based localization approach, which relies on the pairwise (AN-TN) distances estimated by the RCMs. Then, we investigate how the accuracy of the proposed localization algorithm changes if we apply to the distance estimates a recently proposed stochastic correction, which is designed to reduce the distance estimation error. Our experimental results show that a good accuracy is obtained in all the considered scenarios, especially when applying the proposed swarm-based localization algorithm to the stochastically corrected distances. The obtained results are satisfying also in terms of software execution time, making the proposed approach applicable to real-time dynamic localization problems
A kinetic framework to study opinion dynamics in multi-agent systems
No full textIn this paper we summarize an analytic framework to study opinion dynamics. Such a framework is inspired from physics and, in particular, from the kinetic theory of gases with different types of molecules, known as gas mixtures. By reinterpreting the molecules of gases as agents, and the collisions among molecules as interactions among agents, we show how to adapt the kinetic approach to the study of opinion dynamics in multi-agent systems. First, we briefly introduce the key ingredients of the kinetic theory of gas mixtures to clarify nomenclature and to emphasize the substantial differences with the proposed framework. Then, we show how the kinetic approach can be used to study opinion dynamics in multiagent systems, and how a variety of sociological phenomena can be accommodated in the proposed framework. In the last part of the paper we focus on two sociological phenomena, namely compromise and diffusion, and we describe analytic results concerning stationary profiles of the distribution of opinion, and of the temporal evolution of the average opinion and of the variance of the opinion
Kinetic models of relevant phenomena related to opinion dynamics
No full textThis paper outlines recent analytic results regarding the dynamics of the opinion in large multi-agent systems. Discussed results are based on a unifying framework which takes inspiration from mathematical kinetic theories to describe analytically the long-time asymptotic properties of the opinion in large multi-agent systems. Different models to describe the effects of interactions among agents are considered to take into account different sociological phenomena that are known to govern the dynamics of the opinion. For each of such models, the proposed framework allows the analytic derivation of the dynamics of collective properties, such as the average opinion and its variance. Discussed results are in accordance with known empirical evidence, and their analytic form contributes to a solid theory of opinion dynamics
An overview of kinetic approaches to study consensus formation
No full textThis paper discusses some recent results in the study of opinion dynamics and consensus formation in multi-agent systems. While results in these fields are typically obtained by simulation, the adoption of the approach inspired by kinetic theory of gases allows deriving analytic results. More precisely, analytic relationships between the parameters of the model and the asymptotic characteristics of the systems can be analytically determined. Various models inspired from kinetic theory of gases have been studied. For instance, different microscopic phenomena can be investigated, such as compromise and diffusions, and both deterministic and stochastic parameters have been used to model such phenomena. Recently, models inspired from kinetic theory of gas mixtures have also been introduced in the context of opinion dynamics. Such models allow studying multi-agent systems in which different classes of agents coexist. Agents belonging to different classes may be associated with different features, such as the initial distribution of the opinion and the propensity of agents to change their opinions when interacting with other agents. A discussion on the features of different models is presented in this paper
Opinion dynamics in multi-agent systems: selected analytic models and verifying simulations
No full textIn this paper opinion dynamics in multi-agent systems is investigated analytically using a kinetic approach. Interactions among agents are interpreted as collisions among molecules in gases and opinion dynamics is described according to the Boltzmann equation. Starting from a microscopic description of single interactions, global properties of the opinion distribution are derived analytically. The proposed analytic model is general enough to allow reproducing features of real societies of agents, such as positive and negative influences and bounded confidence, which are typically used to study opinion distribution models. Analytic results relative to emergent and global characteristics of considered multi-agent systems are verified by simulations obtained via direct implementation of the proposed microscopic interactions rules. Simulations confirm analytic results
Satisfaction of polynomial constraints over finite domains using function values
No full textThis paper shows how the solutions of constraint satisfac-tion problems that involve only polynomial constraints over finite do-mains can be enumerated by computing the values of related polynomial functions at appropriate points. The proposed algorithm first transforms constraints, which are expressed as equalities, inequalities, and disequal-ities of polynomials with integer coefficients and integer variables, into a canonical form that uses only inequalities. Then, starting from a bound-ing box, which is supposed to be known, the algorithm recursively sub-divides the box into disjoint boxes and it records boxes whose elements satisfy all constraints. The subdivision is driven by the study of the sign of polynomial functions over boxes, which is performed by means of a method that uses only the coefficients of polynomials and the values of functions at the corners of boxes
Polynomial constraint solving over finite domains with the modified Bernstein form
No full textThis paper describes an algorithm that can be used to effectively solve polynomial constraints over finite domains. Such constraints are expressed in terms of inequalities of polynomials with integer coefficients whose variables are assumed to be defined over proper finite domains. The proposed algorithm first reduces each constraint to a canonical form, i.e., a specific form of inequality, then it uses the modified Bernstein form of resulting polynomials to incrementally restrict the domains of variables. No approximation is involved in the solving process because the coefficients of the modified Bernstein form of the considered type of polynomials are always integer numbers
Analytic study of opinion dynamics in multi-agent systems with two classes of agents
No full textThis paper describes a model for opinion dynamics in multi-agent systems composed of two classes of agents. Each class is characterized by distinctive values of the parameters that govern opinion dynamics. The proposed model is inspired by kinetic theory of gases, according to which macroscopic properties of gases are described starting from microscopic interactions among molecules. By interpreting agents as molecules of gases, and their interactions as collisions among molecules, the equations that govern kinetic theory can be reinterpreted to model opinion dynamics in multi-agent systems. A key feature of the adopted kinetic-based approach is that it allows macroscopic properties of the system to be derived analytically. In order to take into account that the considered multi-agent system is composed of two classes of agents, kinetic theory of gas mixtures, which deals with gases composed of different kinds of molecules, is adopted. Presented results show that consensus is reached after a sufficiently large number of interactions, which depends on the parameters associated with the two classes of agents
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