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A three-dimensional Lattice-Boltzmann fluid model with nineteen discrete velocities was implemented using NVIDIA Graphic Processing Unit (GPU) programing language ''Compute Unified Device Architecture'' (CUDA). Previous LBM GPU implementations required two steps to maximize memory bandwidth due to memory access restrictions of earlier versions of CUDA(More)
Image segmentation of 3D medical images is a challenging problem with several still not totally solved practical issues, such as noise interference, variable object structures and image artifacts. This paper describes a hybrid 3D image segmentation method which combines region growing and deformable models to obtain accurate and topologically preserving(More)
The interest in lattice-Boltzmann models in the computational hemodynamics realm has increased in recent years. In this context, the correct choice of numerical parameters for the appropriate simulation of blood flows in major arteries is a crucial aspect. For this reason, we present three parameter-tuning strategies that allow us to reproduce correctly the(More)
A hydrological model based in the cellular automata paradigm, capable to handle extended geographical domains dis-cretized in a large number of cells is presented. The automata simulates the natural surface water flow by tracking local water stocks, book-keeping precipitation, infiltration, evapotranspiration, and intercellular flows. The flow resistance is(More)
A probabilistic algorithm for on-line tomographic reconstruction of ellipse-like images is presented. The algorithm takes advantage of the characteristic preferential direction of the objects, constructing a guidance function to select the angles for subsequent radiographic projections. The simulation results confirm that the technique reduces the number of(More)
A tomographic reconstruction method based on Monte Carlo random searching guided by the information contained in the projections of radiographed objects is presented. In order to solve the optimization problem, a multiscale algorithm is proposed to reduce computation. The reconstruction is performed in a coarse-to-fine multigrid scale that initializes each(More)
A system of two coupled PDEs originally proposed and studied by Kreiss and Yström (2002), which is dynamically similar to a one-dimensional two-fluid model of two-phase flow, is investigated here. It is demonstrated that in the limit of vanishing viscosity (i.e., neglecting second-order and higher derivatives), the system possesses complex eigenvalues and(More)
Object-oriented frameworks are suitable tools to support simulation models of different kinds of collective processes. Software objects, called agents, can perform autonomous tasks, perceiving and reacting to external stimuli, resembling in their way the behavior of fluid particles interacting with the sorrounding environment. In this article, the(More)
A method to simulate graphic animations of objects floating in a water surface in real time is presented. The fluid is simulated by means of the Lattice Boltzmann method for the shallow-waters equations and the movement of the floating objects is calculated with a Newtonian physical engine suitable for the mechanics of rigid bodies. A two-way interaction(More)