Clustered marginalization of minorities during social transitions induced by co-evolution of behaviour and network structure

Large-scale transitions in societies are associated with both individual behavioural change and restructuring of the social network. These two factors have often been considered independently, yet recent advances in social network research challenge this view. Here we show that common features of societal marginalization and clustering emerge naturally during transitions in a co-evolutionary adaptive network model. This is achieved by explicitly considering the interplay between individual interaction and a dynamic network structure in behavioural selection. We exemplify this mechanism by simulating how smoking behaviour and the network structure get reconfigured by changing social norms. Our results are consistent with empirical findings: The prevalence of smoking was reduced, remaining smokers were preferentially connected among each other and formed increasingly marginalised clusters. We propose that self-amplifying feedbacks between individual behaviour and dynamic restructuring of the network are main drivers of the transition. This generative mechanism for co-evolution of individual behaviour and social network structure may apply to a wide range of examples beyond smoking.Comment: 16 pages, 5 figure

An Experimental Collective Intelligence Research Tool

The Collective Intelligence Research Tool (CIRT) is an experimental software and hardware research tool. It provides an inexpensive and efficient alternative research implementation that demonstrates simulations of the collective behaviour of self-organized systems, primarily social insects. The software focuses on 2D simulations of the woodchip-collecting behaviour of termites and 3D simulations of the building behaviour of wasps. The hardware simulation employs a Boe-Bot robot, which has the potential of simulating simple movements of a social insect, by extending its functionality through adding sensors and integrating a control chip

A novel approach to the design of DSP systems using minimum complexity Finite State Machines

The paper presents a new and different approach to the design and realisation of Digital Signal Processing (DSP)systems by utilising Finite State Machines (FSM). The DSP system is modelled by mapping all its potential states into an FSM, whose complexity is usually very high. The FSM mirrors the complete functionality of the system and thus describes its behaviour in full detail. Examples for FSMs of first and second order digital recursive filters are provided and the current version of the software simulating the FSM corresponding to any linear time-invariant DSP system is described. The potential of this approach including state reduction techniques as well as the inclusion of non-linear DSP systems is also outlined, and further future research intentions are briefly explored

Assessment of nonlinear bond laws for near-surface-mounted systems in concrete elements

This paper presents a numerical plane Finite Element (FE) Model for use in simulating the behaviour of different types of Near Surface Mounted (NSM) Fibre Reinforced Plastic (FRP) strengthening systems for concrete elements. Based on a nonlinear bond law for simulating the behaviour of the FRP reinforcement-adhesive-concrete interface, the model employs an interface element between the NSM FRP reinforcement and the concrete. The results of two different experimental programs, both dealing with 'bond tests' but with distinct set-ups, are briefly summarised and analysed. The main objective of this research is to assess the values of the parameters that define the nonlinear bond laws for each type of FRP reinforcement tested. This assessment was accomplished by inverse analysis, fitting numerically the pullout load–displacement curves that were experimentally recorded. The effect of bond length on different types of NSM FRP reinforcement is assessed. Finally, the bond behaviour in the transverse plane is examined too.Fundação para a Ciência e a Tecnologia (FCT

An integrated approach for modelling the tensile behaviour of steel fibre reinforced self-compacting concrete

The present work resumes the experimental and numerical research carried out for the development of a numerical tool able of simulating the tensile behaviour of steel fibre reinforced self-compacting concrete (SFRSCC). SFRSCC is assumed as a two phase material, where the nonlinear material behaviour of SCC matrix is modelled by a 3D smeared crack model, and steel fibres are assumed as embedded short cables distributed within the SCC matrix according to a Monte Carlo method. The internal forces in the steel fibres are obtained from the stress - slip laws derived from the executed fibre pullout tests. The performance of this numerical strategy was appraised by simulating the tensile tests carried out. The numerical simulations showed a good agreement with the experimental results.The first author acknowledges the support provided by the grant SFRH/BD/18002/2004. The study reported in this paper forms a part of the research program PONTALUMIS, Project no. 3456, QREN. The authors also acknowledge the support of Civitest Company on the production of the SFRSCC specimens

Simulating Postbuckling Behaviour and Collapse of Stiffened CFRP Panels

Advanced composite materials are well known for their outstanding potential in weight-related stiffness and strength leading to an ever increasing share in aerospace structural components out of Carbon Fibre Reinforced Plastics (CFRP). In order to fully exploit the load-carrying capacity of such structures an accurate and reliable simulation is indispensable. Local buckling is not necessarily the load bearing limit for stiffened panels or shells; their full potential can be tapped only by utilizing the postbuckling region. That, however, requires fast tools which are capable of simulating the structural behaviour beyond bifurcation points including material degradation up to collapse. The most critical structural degradation mode is skin stringer separation; delamination, especially within the stringer, is a critical material degradation. A reliable prediction of collapse requires knowledge of degradation due to static as well as low cycle loading in the postbuckling region. Earlier projects have shown that it needs considerable experience in simulating the postbuckling behaviour. Though a great deal of knowledge about CFRP structural and material degradation is available its influence on collapse is not yet sufficiently investigated. It is the aim of the project COCOMAT (Improved MATerial exploitation at safe design of COmposite airframe structures by accurate simulation of COllapse) to develop means for and gain experience in fast and accurate simulation of the collapse load of stringer stiffened CFRP curved panels taking degradation and cyclic loading as well as geometric nonlinearity into account. COCOMAT is a Specific Targeted Research Project supported by the EU 6th Framework Programme; it started 2004 and runs for 4 years. Main deliverables are: • test results for buckling and collapse of undamaged and pre-damaged stiffened CFRP panels under static and cyclic loading, • improved material properties and degradation models, computational tools for design and certification of stiffened fibre composite panels which take postbuckling behaviour, degradation and collapse into account, • and finally design guidelines and industrial validation. The work will lead to an extended experimental data base, relevant degradation models and improved simulation tools for certification as well as for design. These results should allow setting up a future design scenario which exploits the existing reserves in primary fibre composite structures. The paper starts out from results provided by the forerunners of COCOMAT, describes the main objectives of the project, gives a general status of the progress reached so far and presents first results

Simulating Dynamical Features of Escape Panic

One of the most disastrous forms of collective human behaviour is the kind of crowd stampede induced by panic, often leading to fatalities as people are crushed or trampled. Sometimes this behaviour is triggered in life-threatening situations such as fires in crowded buildings; at other times, stampedes can arise from the rush for seats or seemingly without causes. Tragic examples within recent months include the panics in Harare, Zimbabwe, and at the Roskilde rock concert in Denmark. Although engineers are finding ways to alleviate the scale of such disasters, their frequency seems to be increasing with the number and size of mass events. Yet, systematic studies of panic behaviour, and quantitative theories capable of predicting such crowd dynamics, are rare. Here we show that simulations based on a model of pedestrian behaviour can provide valuable insights into the mechanisms of and preconditions for panic and jamming by incoordination. Our results suggest practical ways of minimising the harmful consequences of such events and the existence of an optimal escape strategy, corresponding to a suitable mixture of individualistic and collective behaviour.Comment: For related information see http://angel.elte.hu/~panic, http://www.helbing.org, http://angel.elte.hu/~fij, and http://angel.elte.hu/~vicse

Simulating the conflict between reputation and profitability for online rating portals

We simulate the process of possible interactions between a set of competitive services and a set of portals that provide online rating for these services. We argue that to have a profitable business, these portals are forced to have subscribed services that are rated by the portals. To satisfy the subscribing services, we make the assumption that the portals improve the rating of a given service by one unit per transaction that involves payment. In this study we follow the 'what-if' methodology, analysing strategies that a service may choose from to select the best portal for it to subscribe to, and strategies for a portal to accept the subscription such that its reputation loss, in terms of the integrity of its ratings, is minimised. We observe that the behaviour of the simulated agents in accordance to our model is quite natural from the real-would perspective. One conclusion from the simulations is that under reasonable conditions, if most of the services and rating portals in a given industry do not accept a subscription policy similar to the one indicated above, they will lose, respectively, their ratings and reputations, and, moreover the rating portals will have problems in making a profit. Our prediction is that the modern portal-rating based economy sector will eventually evolve into a subscription process similar to the one we suggest in this study, as an alternative to a business model based purely on advertising

The simulation of action disorganisation in complex activities of daily living

Action selection in everyday goal-directed tasks of moderate complexity is known to be subject to breakdown following extensive frontal brain injury. A model of action selection in such tasks is presented and used to explore three hypotheses concerning the origins of action disorganisation: that it is a consequence of reduced top-down excitation within a hierarchical action schema network coupled with increased bottom-up triggering of schemas from environmental sources, that it is a more general disturbance of schema activation modelled by excessive noise in the schema network, and that it results from a general disturbance of the triggering of schemas by object representations. Results suggest that the action disorganisation syndrome is best accounted for by a general disturbance to schema activation, while altering the balance between top-down and bottom-up activation provides an account of a related disorder - utilisation behaviour. It is further suggested that ideational apraxia (which may result from lesions to left temporoparietal areas and which has similar behavioural consequences to action disorganisation syndrome on tasks of moderate complexity) is a consequence of a generalised disturbance of the triggering of schemas by object representations. Several predictions regarding differences between action disorganisation syndrome and ideational apraxia that follow from this interpretation are detailed