Catálogo de publicaciones - libros

The application of the Orthogonal Organized Finite State Machine (OOFSM) to the representation of data acquired by sensor networks is proposed. The OOFSM was proposed in earlier work; it is succinctly reviewed here. The approach and representation of the OOFSM to sensor acquired data is formalized. The usefulness of this OOFSM application is illustrated by several case studies, specifically, gradients, contouring and discrete trajectory path determination. In addition, this paper informally discusses the OOFSM as a Cellular Automata.

The numerical analysis of some broadband electromagnetic fields and frequency-dependent materials using a time domain method is the main subject of this paper. The spatial and time-dependent distribution of the electromagnetic field is approximated by the finite element method. The parallel form of the algorithm valid for some linear materials, and the formulation of the FE code for a dispersive electromagnetic problem are presented and compared. The complex forms of these algorithms have an effect on the memory and computational costs of the distributed formulation. The properties of the algorithm are estimated using high performance cluster of workstations.

Protoplanetary disc simulation must be done first, with high precision, and second, with high speed. Some strategies to reach these goals are presented in the paper. They include: the reduction of the 3D protoplanetary disc model to quasi-3D, the use of fundamental Poisson equation solution, the simulation in the natural (cylindrical) coordinate system and computation domain decomposition. The domain decomposition strategy is shown to reach the simulation goals the best.

Web Search Engine uses forward indexing and inverted indexing as a part of its functional design. This indexing mechanism helps retrieving data from the database based on user query. In this paper, an efficient solution to handle the indexing problem is proposed with the introduction of Nonlinear Single Cycle Multiple Attractor Cellular Automata (SMACA). This work simultaneously shows generation of SMACA by using specific rule sequence. Searching mechanism is done with linear time complexity.

The running times of large-scale computational science and engineering parallel applications, executed on clusters or Grid platforms, are usually longer than the mean-time-between-failures (MTBF). Therefore, hardware failures must be tolerated to ensure that not all computation done is lost on machine failures. Checkpointing and rollback recovery are very useful techniques to implement fault-tolerant applications. Although extensive research has been carried out in this field, there are few available tools to help parallel programmers to enhance their applications with fault tolerance support. This work presents an experience to endow with fault tolerance two large MPI scientific applications: an air quality simulation model and a crack growth analysis. A fault tolerant solution has been implemented by means of a checkpointing and recovery tool, the CPPC framework. Detailed experimental results are presented to show the practical usefulness and low overhead of this checkpointing approach.

We describe parallel numerical code for solving problems of stellar dynamics. The code is based on numerical solving of Poisson and Vlasov equations in cylindrical coordinates using particle-in-cells method. The code is designed for use on supercomputers with distributed memory. We consider different possible strategies of parallelization according to initial technical parameters of numerical methods and physical conditions of the model. We present results of numerical simulations for the following problems of stellar dynamics: investigation of influence of central potential on the vertical motions of thin gravitating disk; stability of uniform sphere with anisotropic distribution of velocity; numerical approximation of equilibrium states of gravitating systems.

In this paper, the authors propose a numerical investigation in the time domain of the mechanical wave propagation due to an impulsional load on a semi-infinite soil. The ground is modelled as a porous saturated viscoelastic medium involving the complete Biot theory. An accurate and efficient Finite Element Method using a matrix-free technique is used. Two parallel algorithms are used: Geometrical Domain Decomposition (GDD) and Algebraic Decomposition (AD). Numerical results show that GDD algorithm has the best time. Physical numerical results present the displacements of the fluid and solid particles over the surface and in depth.

The number of sequenced genes is dramatically increasing with that of international genomic projects. The gene sequence information proved to be helpful in predictions of protein structure, protein function and mutations targeted at improving the biological and biotechnological properties of proteins. Processing of the immense information stored in the databases demands high-throughput computational approaches. Here, we performed a parallelization of the algorithm for analysis of nucleotide substitutions in gene sequences from different organisms previously implemented in the PLATO program. The results demonstrated that the parallelization of the algorithm provides linear speedup of the PLATO program.

MPI is commonly used standard in development of scientific applications. It focuses on interlanguage operability and is not very well object oriented. The paper proposes a general pattern enabling design of distributed and object oriented applications. It also presents its sample implementations and performance tests.

Dealing with a large amount of data in Data Grids makes the requirement for efficient data access more critical. In this paper, we proposed a new approach to replication problem by organizing the data into several data categories that it belongs to. This organizing will help improving placement strategy of data replication. We studied our approach in combination with scheduling issue and evaluating it through simulation. The result shows that our strategy has improved the scheduling performance by 30%.