Catálogo de publicaciones - libros

Since the first software programs for evacuation simulations were applied to ships, questions about the influence of the ship motions, and how these could be taken into account, came up. As the acceptance of simulation tools was pushed by the developments at the International Maritime Organization, research was undertaken by various institutes and the appropriate data was collected. The paper describes, how a model for the implementation of ship motions into the software AENEAS was developed and how the ship motions influence the results of the evacuation analysis. The implementation of ship motion is part of a research project, funded by the German Ministry of Transportation (BMVBW) and organised by the Hamburgische Schiffbau-Versuchsanstalt (HSVA).

Evacuation analysis of passenger and commercial shipping can be undertaken using computer-based simulation tools such as maritimeEXODUS. These tools emulate human shipboard behaviour during emergency scenarios; however it is largely based around the behaviour of civilian passengers and fixtures and fittings of merchant vessels. If these tools and procedures are to be applied to naval vessels there is a clear requirement to understand the behaviour of well-trained naval personnel interacting with the fixtures and fittings that are exclusive to warships.

Human factor trials using Royal Navy training facilities were recently undertaken to collect data to improve our understanding of the performance of naval personnel in warship environments. The trials were designed and conducted by staff from the Fire Safety Engineering Group (FSEG) of the University of Greenwich on behalf of the Sea Technology Group (STG), Defence Procurement Agency. The trials involved a selection of RN volunteers with sea-going experience in warships, operating and traversing structural components under different angles of heel. This paper describes the trials and some of the collected data.

The spatial distribution of individuals is an important subject in many fields because it conditions the levels of interactions among individuals, and more generally the structuring as well as the organization of populations. Increase in density of individuals in a given area can be induced by environmental stimuli and/or by interactions among individuals (1–3). Thus, various definitions of aggregation have been given, ecologists privilege the importance of environmental stimuli, while others privilege existing relationships between group members.

Aggregation is one of the most widespread social phenomena and occurs at all biological levels, from bacteria to mammals including humans (4, 5). If sometimes, aggregation is associated to non-adaptive, often it is the ground on which more complex social structures are built such as synchronization or division of labour (6). However, knowledge of the mechanisms implied in the formation of aggregates remains fragmentary. The study of the proximal causes, i.e. mechanisms involved in group formation, can benefit from concepts of self-organization (5, 7). These groups find their origin and their cohesion in the inter-attraction among individuals: group members are then the source of attraction. However, in most of the situations, patterns of aggregation, resulting from individual responses to conspecifics are modulated by environmental heterogeneity (5).

Previous studies on cockroaches have already described their aggregative distribution in a natural environment where different age-classes share the resources that are present in their home range. They exhibit a strong tendency to gather during their resting period in safe shelters. Therefore, shelters are important, but also limited environmental resources for these insects.

The basic mechanisms underlying group formation is the modulation of the individual resting time as a function of the number of conspecifics on a site. In insects cuticular hydrocarbons act as a recognition signal allowing attraction between individuals (8). Cockroaches prefer their own strain odour to another strain (9). Nevertheless, when groups in tests came from two different strains, they aggregated on one site only and did not show any difference from group coming from one strain.

We used this insect as an example to show that a self-organized process leads to a diversity of optimal patterns without modification of the individual behaviours and any general knowledge of the available resources. These experimental and theoretical results point to a generic self-organized pattern-formation process independent of the level of animal sociability that should be found in other group-living organisms that present inter-attraction.

We generalize cellular automaton models for uni-directional ant-trails to bi-directional motion. Several extensions (1-lane, 2-lane with and without common pheromone trail) corresponding to different realistic situations are compared. The interactions between the ants give rise to interesting collective behavior which is reflected in the flow properties and the spatio-temporal organization of the ants along the trail.

We introduce the element of copying in an agent-based model of escape panic to describe with greater accuracy the exit behavior of mice that are escaping from a flooded two-exit chamber. Aside from the panic threshold ϕ (0 ≤ ϕ ≤ 5), our model utilizes the imitation tendency α (0 ≤ α ≤ 1) such that agents with ϕ = 0, are calm and tend to stay put while those that are likely to copy their neighbors are described by large α values. A high degree of copying among escaping agents favors the emergence of herding behavior. Both the Moore and the von Neumann neighborhood are tried to depict the movement of agents in a plane. Herding decreases the exit throughput Q by causing an inefficient utilization of the two available exits for escape. The dependence of Q with α and the exit door separation are highly nonlinear. The inclusion of α has significantly improved the capability of our model to explain the Q-behavior that was observed in the mice experiments. Interestingly, simulation results show that copying could promote faster room evacuation at α ≈ 0.5 and especially at high room occupancy rates (> 60%). At α ≈ 0.5, an agent is equally likely to copy or ignore the action of its neighbor.

Many insects like, for example, ants communicate via chemical signals. This process, called chemotaxis, allows them to build large trail systems which have many similarities with human transport networks. In order to investigate the dynamics and spatio-temporal organization of ants on an existing trail system we have proposed a stochastic cellular automaton model. In contrast to the situation in highway traffic, it predicts a non-monotonic speed-density relation. This effect has its origin in the formation of loose clusters, i.e. space regions of enhanced, but not maximal, density. Inspired by the behaviour of ants on their trails, we have also developed a model for pedestrian dynamics. In this approach the interaction between the pedestrians is implemented as “virtual chemotaxis”. In this way all interactions are strictly local and so even large crowds can be simulated very efficiently. In addition, the model is able to reproduce the empirically observed collective effects, e.g. the formation of lanes in counterflow.