Catálogo de publicaciones - libros

This paper proposes a spherical parameterization based remeshing approach to converting a given unstructured triangle mesh with boundaries into one having subdivision connectivity. In order to preserve the boundaries of original meshes, some special strategies are introduced into the remeshing procedure.

In this paper, a method is proposed to retrieve desired 3D models by measuring the similarity between a user’s freehand sketches and 2D orthogonal views generated from 3D models. The proposed method contains three parts: (1) pose determination of a 3D model; (2) 2D orthogonal view generation along the orientations; and (3) similarity measurement between a user’s sketches and the 2D views. Users can submit one, two or three views intuitively as a query, which are similar to the three main views in engineering drawing. It is worth pointing point out that our method only needs three views, while 13 views is the minimum set that has been reported by other researchers.

A stochastic two-state epidemiological cellular automaton model is studied, where sites move between susceptible and infected states. Each time step has two phases: an infectious phase, followed by a treatment or recovery phase. During the infectious phase, each infected site stochastically infects its susceptible neighbors. During the recovery phase, contiguous blocks of sites are reset to the susceptible state, representing spatially clustered treatment or recovery. The spatially extended recovery events are coordinated events over groups of cells larger than standard local neighborhoods typically used in cellular automata models. This model, which exhibits complex spatial dynamics, is investigated using simulations, mean field approximations, and local structure theory, also known as pair approximation in the ecological literature. The spatial scale and geometry of recovery events affects the equilibrium distribution of the model, even when the probability of block recovery events is rescaled to maintain a constant per-site recovery probability per time step. Spatially clustered treatments reduce the equilibrium proportion of infected invididuals, compared to spatially more evenly distributed treatment efforts.

CD++ is an implementation of the Cell-DEVS formalism, which has been used to simulate various complex systems. In this study, we constructed a Cell-DEVS to simulate the dynamics of a dual market. Using new features of CD++, we obtained accurate results taking into account consumers’ purchasing history. The resulting model allows fast execution, easier model implementation and maintenance.

Cell-DEVS is a combination of CA with the DEVS formalism that allows the definition of cellular models. CD++ is a modeling and simulation tool that implements DEVS and Cell-DEVS. We have used CD++ to build a model about competition between population and viruses. We will discuss how to define such a model in CD++, and will show simulation results under different scenarios.

Motivated by noise-driven cellular automata models of self-organized criticality (SOC), a new paradigm for the treatment of hard combinatorial optimization problems is proposed. An extremal selection process preferentially advances variables in a poor local state. The ensuing dynamic process creates broad fluctuations to explore energy landscapes widely, with frequent returns to near-optimal configurations.

In von Neumann 29-state cellular automata, the crossing of signals is an important problem, with three solutions reported in the literature. These solutions greatly impact automaton design, especially self-replicators. This paper examines these solutions, with emphasis upon their constructibility. We show that two of these solutions are difficult to construct, and offer an improved design technique. We also argue that solutions to the signal-crossing problem have implications for machine models of biological development, especially with regard to the cell cycle.

In this paper we describe our recent use of genetic programming methods to automatically discover CA rule sets that produce self-replication of arbitrary given structures. Our initial results have produced larger, more rapidly replicating structures than past evolutionary models while requiring only a small fraction of the computational time needed in past similar studies. We conclude that genetic programming provides a very powerful tool for discovering novel CA models of self-replicating systems and possibly other complex systems.

The brood sorting behavior of ants like Leptothorax unifasciatus leads to patterns, where brood items are sorted in concentric circles around the nest center. The underlying mechanisms are not fully understood so far and brood tending simulations can help to explain the occurrence of these patterns. We reexamine an existing cellular automata based model for ant brood tending. This model is then modified and extended by including a carbon dioxide distribution in the nest, that influences the ants movement behavior. Furthermore, the ants can deliver food to the brood in our model. Results of simulation runs are presented that can help to explain brood patterns that have been observed in natural ant colonies.

Complexity and abstraction provide a fertile frontier by which to express and experience complex systems in art, with integral challenges for abstract painting: Can we create complex art without a computer? What are the simple rules by which to create that art? The author proposes a model of the artist and her materials as a cellular automaton (CA) with eight simple rules. Experiments with the New Kind of Science (NKS) Rule 1599 algorithm, abstract painting and video shorts are discussed with four observations about the plurality of CA visualization, a new abstract visual language that embraces emergence, the discovery of “eddies” of complexity within the paintings, and the resemblance of these eddies to other complex phenomena found in nature and culture. Future exploration merits investigation into the neural basis of art, and experimentation in the synaesthesic experience of complexity.