Stefania Bandini

Cellular automata: from a theoretical parallel computational model to its application to complex system

This introductory paper gives a short survey of cellular automata (CAs), from different points of view. It starts with the main definitions and theoretical results about CAs as an abstract model of computation or as discrete dynamical systems. Then, the main applications of CAs in different fields (biology, physics, etc.) as a model of complex systems are illustrated. Finally, implementations of the CA model on parallel computing platforms are surveyed.

SITUATED CELLULAR AGENTS APPROACH TO CROWD MODELING AND SIMULATION

The article describes a multi-agent approach to crowd modeling and simulation. After a brief introduction of the Situated Cellular Agents model, the guidelines to the crowd modeling approach is introduced as a way to support the communication among the different actors that are part of the simulation project team. The approach is then applied to describe a complex scenario providing a blend of competitive and cooperative behavior for pedestrian agents: an underground station. A module supporting the effective 3D visualization of simulated crowd dynamics is finally introduced, as an instrument for the communication of simulation results to decision makers and nonexperts in crowd phenomena.

Towards an integrated approach to crowd analysis and crowd synthesis

An adaptive model for the simulation of groups of pedestrians able to preserve their cohesion.An observation and analysis of groups of pedestrians in a real world situation.An integrated framework for crowd analysis and synthesis. Studies related to crowds of pedestrians, both those of theoretical nature and application oriented ones, have generally focused on either the analysis or the synthesis of the phenomena related to the interplay between individual pedestrians, each characterised by goals, preferences and potentially relevant relationships with others, and the environment in which they are situated. The cases in which these activities have been systematically integrated for a mutual benefit are still very few compared to the corpus of crowd related literature. This paper presents a case study of an integrated approach to the definition of an innovative model for pedestrian and crowd simulation (on the side of synthesis) that was actually motivated and supported by the analyses of empirical data acquired from both experimental settings and observations in real world scenarios. In particular, we will introduce a model for the adaptive behaviour of pedestrians that are also members of groups, that strive to maintain their cohesion even in difficult (e.g., high density) situations. The paper will show how the synthesis phase also provided inputs to the analysis of empirical data, in a virtuous circle.

An agent model of pedestrian and group dynamics: experiments on group cohesion

The simulation of pedestrian dynamics is a consolidated area of application for agent-based based models; however generally the presence of groups and particular relationships among pedestrians is treated in a simplistic way. This work describes an innovative agent-based based approach encapsulating in the pedestrians behavioural model effects representing both proxemics and a simplified account of influences related to the presence of groups in the crowd. The model is tested in a simple scenario to evaluate the effectiveness of mechanisms to preserve groups cohesion maintaining a plausible overall crowd dynamic.

Towards a methodology for situated cellular agent based crowd simulations

This paper introduces a research activity aimed at the definition of a methodology to provide a solid conceptual framework for the development of simulation systems focused on crowd dynamics and based on the Situated Cellular Agent (SCA) model. After a brief introduction of the SCA Model, the general methodological approach is described. The main steps provide the definition of the spatial abstraction of the environment, the definition of its active elements, and the specification of types of mobile agents, the related behaviours with particular attention to their movement by means of the notion of utility. A case study is also briefly described in order to show how the methodology was applied in the modelling of crowd behaviour in an underground station.

Design issues for knowledge artifacts

The notion of knowledge artifact has rapidly gained popularity in the fields of general knowledge management and more recently knowledge-based systems. The main goal on this paper is to propose and discuss a methodology for the design and implementation of knowledge-based systems founded on knowledge artifacts. We advocate that the systems built according to this methodology can be effective to convey the flow of knowledge between different communities of practice. Our methodology has been developed from the ground up, i.e. we have built some concrete systems based on the abstract notion of knowledge artifact and synthesized our methodology based on reflections upon our experiences building these systems. In this paper, we also describe the most relevant systems we have built and how they have guided us to the synthesis of our proposed methodology.

An analysis of different types and effects of asynchronicity in cellular automata update schemes

This paper introduces the problematics deriving from the adoption of asynchronous update schemes in CA models. Several cellular automata update schemes and a tentative classification of such schemes are introduced and discussed. In order to analyze the effects of the different update schemes, a class of simple CA—called One neighbor binary cellular automata (1nCA)—is then introduced. An overview of the general features of 1nCA is described, then the effects of six different updates schemes on all the class of 1nCA are described.

Commonsense spatial reasoning for context–aware pervasive systems

A major issue in Pervasive Computing in order to design and implement context–aware applications is to correlate information provided by distributed devices to furnish a more comprehensive view of the context they habit. Such a correlation activity requires considering a spatial model of this environment, even if the kind of information processed is not only of spatial nature. This paper focuses on the notions of place and conceptual spatial relation to present a commonsense formal model of space supporting reasoning about meaningful correlation. The model consists of a relational structure that can be viewed as the semantic specification for a hybrid logic language, whose formulas represent contextual information and whose satisfiability procedures enhance reasoning, allowing the local perspective typical of many approach to context–awareness.

Enhancing Cellular Spaces by Multilayered Multi Agent Situated Systems

This paper presents the formal description of the Multilayered Multi-Agent Situated System (MMASS) which can be seen as a generalization of cellular spaces since it relaxes some constraints on uniformity, locality and closure. MMASS allows the description, representation and simulation of complex systems that explicitly require to consider spatial features. Different forms of interaction are possible within a MMASS: synchronous reaction between spatially adjacent agents and asynchronous and at-a-distance interaction through a field emission-propagation-perception mechanism.

Mobility analysis of the aged pedestrians by experiment and simulation

In coming decade, the aging rate will dramatically increase in advanced countries.Focus on the mobility issues where the elderly and young pedestrians are mixed.Cellular Automata model is created with aid of experiments.The model shows reasonable consistency with the experimental result.The compatibility of elderlys safety and youngs mobility is discussed. The relative weight of the population shifts from younger to elderly in the most of the region on the planet. Current aging rate in the advanced nations varies from 12% to 13% and is expected to increase up to 21-37% in 2050. The increase of aging rate in the society especially in the large city will lead a mobility problem. From a social quality point of view, it is important to achieve the compatibility between safety and mobility respectively for younger and elderly generation. For the purpose of understanding the basic characteristics of the pedestrian dynamics under cohabitation of younger and elderly generation, a Cellular Automata (CA) model is created with the aid of pedestrian experiments. Simulations are carried out to reproduce the experimental results and had shown a good agreement.