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January 2000 - present

## Publications

Publications (85)

There is a growing interest in biomedical engineering in developing procedures that provide accurate simulations of the neural response to electrical stimulus produced by implants. Moreover, recent research focuses on models that take into account individual patient characteristics.
We present a phenomenological computational model that is customiz...

A novel phenomenological epidemic model is proposed to characterize the state of infectious diseases and predict their behaviors. This model is given by a new stochastic partial differential equation that is derived from foundations of statistical physics. The analytical solution of this equation describes the spatio-temporal evolution of a Gaussia...

Environmental studies on coastal dune systems are faced with a considerable cost barrier due to the cost of the instrumentation and sensory equipment required for data collection. These systems play an important role in coastal areas as a protection against erosion and as providers of stability to coastal sedimentary deposits. The DIY (Do-It-Yourse...

This paper compares methods for simultaneous mesh untangling and quality improvement that are based on repositioning the vertices. The execution times of these algorithms vary widely, usually with a trade-off between different parameters. Thus, computer performance and workloads are used to make comparisons. A range of algorithms in terms of qualit...

Many mesh optimization applications are based on vertex repositioning algorithms (VrPA). Since the time required for VrPA programs may be large and there is concurrency in processing mesh elements, parallelism has been used to improve performance. In this paper, we propose a performance model for parallel VrPA algorithms that are implemented on mem...

Many mesh optimization applications are based on vertex repositioning algorithms (VrPA). The execution times of these numerical algorithms vary widely, usually with a trade-off between different parameters. In this work, we analyze the impacts of six parameters of sequential VrPA on runtime. Our analysis is used to propose a new workload measure ca...

We propose a new algorithm on distributed-memory parallel computers for our simultaneous untangling and smoothing of tetrahedral meshes [9, 10]. A previous parallel implementation on shared-memory computers is analyzed in [1]. The new parallel procedure takes ideas from Freitag et al. strategy [11]. The method is based on: partitioning a mesh, opti...

Probabilistic wind forecasting is a methodology to deal with uncertainties in numerical weather prediction models (NWP). In this chapter, we describe the need for ensemble forecasting, the different techniques used to generate the different initial conditions, and the operational ensemble models that are used nowadays in meteorological agencies. Th...

This chapter describes Wind3D, a mass-consistent diagnostic model with an updated vertical wind profile and atmospheric parameterization. First, a description of Wind3D is provided, along with their governing equations. Next, the finite element formulation of the model and the description of the solver of the corresponding linear system are present...

This chapter is devoted to the introduction of some geographical and meteorological information involved in the numerical modeling of wind fields and solar radiation. First, a brief description of the topographical data given by a Digital Elevation Model and Land Cover databases is provided. In particular, the Information System of Land Cover of Sp...

The characterisation of the aerodynamic roughness length (z0) and the displacement height (d) is critical when
modelling the wind field using the log vertical profile. It is known that the values of these parameters depend on land coverage and weather conditions. Thus, many authors have studied their relationship, providing typical values for each...

Solar radiation numerical models need the implementation of an accurate method for determining cast shadows on the terrain or on solar collectors. The aim of this work is the development of a new methodology to detect the shadows on a particular terrain. The paper addresses the detection of self and cast shadows produced by the orography as well as...

A solar radiation numerical model is presented. With it, the user can estimate the radiation values in any location easily and compute the solar power generation taking into account not only the radiation level, but also the terrain surface conditions considering the cast shadows. The terrain surface is taken into account, using 2-D adaptive meshes...

A parallel algorithm for simultaneous untangling and smoothing of tetrahedral meshes is proposed in this paper. This algorithm is derived from a sequential mesh optimization method. We provide a detailed analysis of its parallel scalability and efficiency, load balancing, and parallelism bottlenecks using six benchmark meshes. In addition, the infl...

The classical optimal (in the Frobenius sense) diagonal preconditioner for large sparse linear systems Ax=bAx=b is generalized and improved. The new proposed approximate inverse preconditioner NN is based on the minimization of the Frobenius norm of the residual matrix AM−IAM−I, where MM runs over a certain linear subspace of n×nn×n real matrices,...

A predictive solar radiation numerical model for the estimation of the photovoltaic power generation in the medium term is presented. This tool allows the user to predict the solar radiation as well as the photovoltaic power generation, with a given probability. The work has been applied in Gran Canaria (Canary Islands – Spain), but the model is us...

A solar radiation numerical model is presented. With it, the user can estimate the radiation values in any location easily and compute the solar power generation taking into account not only the radiation level, but also the terrain surface conditions considering the cast shadows. The terrain surface is taken into account, using 2-D adaptive meshes...

In this paper, we introduce a new method for wind field forecasting over complex terrain. The main idea is to use the predictions of the HARMONIE meso-scale model as the input data for an adaptive finite element mass-consistent wind model. The HARMONIE results (obtained with a maximum resolution of about 1 km) are refined in a local scale (about a...

A new parallel algorithm for simultaneous untangling and smoothing of tetrahedral meshes is proposed in this paper. We provide a detailed analysis of its performance on shared-memory many-core computer architectures. This performance analysis includes the evaluation of execution time, parallel scalability, load balancing, and parallelism bottleneck...

A three-dimensional finite element model for the pollutant dispersion is presented. In these environmental processes over a complex terrain, a mesh generator capable of adapting itself to the topographic characteristics is essential. The first stage of the model consists on the construction of an adaptive tetrahedral mesh of a rectangular region bo...

The meccano method is a novel and promising mesh generation technique for simultaneously creating adaptive tetrahedral meshes and volume parameterizations of a complex solid. The method combines several former procedures: a mapping from the meccano boundary to the solid surface, a 3-D local refinement algorithm and a simultaneous mesh untangling an...

Nowadays the solar power is one of the most appreciate renewable energies in the world. In order to maximise the solar radiation collection, many numerical models have been developed. There are three groups of factors that determines the interaction of solar radiation with the earths atmosphere and surface (see e.g. (1)): a. The Earths geometry, re...

In this paper we propose a finite element method approach formodelling the air quality in a local scale over complex terrain. The area of interest is up to tens of kilometres and it includes pollutant sources. The proposed methodology involves the generation of an adaptive tetrahedral mesh, the computation of an ambient wind field, the inclusion of...

A solar radiation numerical model is presented. It is intented to be useful for different purposes like the evaluation of the suitability of possible locations for solar power stations. This model allows the user to evaluate the radiation values in any location easily, and estimate the solar power generation taking into account not only the radiati...

We present a new method to construct a trivariate T-spline representation of complex solids for the application of isogeometric analysis. We take a genus-zero solid as a basis of our study, but at the end of the work we explain the way to generalize the results to any genus solids. The proposed technique only demands a surface triangulation of the...

In this paper we propose a finite element method approach for modelling the air quality in a local
scale over complex terrain. The area of interest is up to tens of kilometres and it includes pollutant sources. The proposed methodology involves the generation of an adaptive tetrahedral mesh, the computation of an ambient wind field, the inclusion o...

We present a new method to construct a trivariate T-spline representation of complex genus-zero solids for the application of isogeometric analysis. The proposed technique only demands a surface triangulation of the solid as input data. The key of this method lies in obtaining a volumetric parameterization between the solid and the parametric domai...

Conventional air quality models uses Lagrangian [1,2] or Eulerian [3] strategies, and the numerical approach is normally obtained by using finite difference schemes. In this paper, we introduce a local scale Eulerian air pollution model that is related to unsteady propagation problems which may be mathematically described by convection-diffusion-re...

In this work we develop a procedure to deform a given surface triangulation to obtain its alignment with inte-rior curves. These curves are defined by splines in a paramet-ric space and, subsequently, mapped to the surface triangu-lation. We have restricted our study to orthogonal mapping, so we require the curves to be included in a patch of the s...

In previous works, many authors have widely used mass consistent models for wind field simulation by the finite element method. On one hand, we have developed a 3-D mass consistent model by using tetrahedral meshes which are simultaneously adapted to complex orography and to terrain roughness length. In addition, we have included a local refinement...

In this paper, we present significant advances of the novel meccano technique for simultaneously constructing adaptive tetrahedral
meshes of 3-D complex solids and their volume parametrization. Specifically, we will consider a solid whose boundary is a
surface of genus zero. In this particular case, the automatic procedure is defined by a surface t...

The meccano method is a novel and promising mesh generation method for simultaneously creating adaptive tetrahedral meshes and volume parametrizations of a complex solid. We highlight the fact that the method requires minimum user intervention and has a low computational cost. The method builds a 3-D triangulation of the solid as a deformation of a...

Title:
Photovoltaic Power Estimation Tool Using a Solar Radiation Numerical Model
Abstract/Summary:
A tool based on a solar radiation numerical model for the evaluation of the suitability of different possible locations for photovoltaic power stations is presented. It allows the user to estimate the solar radiation in a given place as well as th...

A numerical model for generating solar radiation maps to be used for the evaluation of different power generation strategies is proposed. The solar radiation model is implemented taking into account the terrain surface with the use of 2-D adaptive meshes of triangles, which are made using a refinement/derefinement procedure in accordance with the v...

In this paper, we present significant advances of the novel meccano technique to construct adaptive tetrahedral meshes of 3-D complex solids. Specifically, we will consider a solid whose boundary is a surface of genus 0, i.e. a surface that is homeomorphic to the surface of a sphere. In this particular case, the automatic procedure is defined by a...

This paper introduces a new automatic strategy for adaptive tetrahedral mesh generation. A local refinement/derefinement algorithm for nested triangulations and a simultaneous untangling and smoothing procedure are the main involved techniques. The mesh generator is applied to 3-D complex domains whose boundaries are projectable on external faces o...

In this work, we propose a numerical model for generating solar radiation maps with the use of 2-D adaptive meshes of triangles. These triangulations are constructed by using a refinement/derefinement procedure in accordance with the variations of terrain surface orography and albedo. This discretization has the advantage of defining the terrain ch...

In this paper we introduce an automatic tetrahedral mesh generator for complex genus-zero solids, based on the novel meccano
technique. Our method only demands a surface triangulation of the solid, and a coarse approximation of the solid, called meccano,
that is just a cube in this case. The procedure builds a 3-D triangulation of the solid as a de...

Mass consistent models have been widely use in 3-D wind modelling by finite element method. We have used a method for constructing
tetrahedral meshes which are simultaneously adapted to the terrain orography and the roughness length by using a refinement/derefinement
process in a 2-D mesh corresponding to the terrain surface, following the techniqu...

In this work we develop a procedure to deform a given surface triangulation to obtain its alignment with interior curves.
At present, we consider that these curves are defined by the orthogonal projection from plane cubic splines to the initial
surface triangulation. For example, the curves can represent interfaces between different materials or bo...

In this work we develop a procedure to deform a given surface triangulation to obtain its exact alignment with interior curves. These curves, defined by splines, can represent internal interfaces between different materials, internal boundaries, etc. An important feature of this procedure is the possibility to adapt a reference mesh to curves that...

This paper introduces a new automatic strategy for adaptive tetrahedral mesh generation. A local refinement/derefinement algorithm for nested triangulations and a simultaneous untangling and smoothing procedure are the main involved techniques. The mesh generator is applied to 3-D complex domains whose boundaries are projectable on external faces o...

This work focuses in the simulation of transport and reaction of pollutant emissions from high stacks with the Finite Element Method. Nowadays tendencies on numerical modelling of punctual emission sources are analyzed. The so-called hybrid models are one of the best available options. These models simulate the pollutant evolution in the microscale...

This paper presents a new procedure to improve the quality of triangular meshes defined on surfaces. The improvement is obtained by an iterative process in which each node of the mesh is moved to a new position that minimizes a certain objective function. This objective function is derived from algebraic quality measures of the local mesh (the set...

This paper introduces a new automatic tetrahedral mesh generator on the adaptive finite element ALBERTA code. The procedure can be applied to 3- D domains with boundary surfaces which are projectable on faces of a cube. The generalization of the mesh generator for complex domains which can be split into cubes or hexahedra is straightforward. The do...

Mass consistent models have been widely use in three-dimensional wind modelling by finite element method. In general, these problems are defined over regions with complex terrain and variable roughness length, therefore a suitable discretization of the studied zone will be necessary. In addition, there often exist points where more accuracy is requ...

The refinement technique is used to adapt meshes to the singularities of the numerical solution of any problem. Local refinement is applied is mesh areas where the solution must be accurate and it is necessary to dispose of reliable error indicators or estimators which define the elements that must be refined. Usually, this indicators or estimators...

The improvement in the mesh quality without changing its connectivity is bounded. This bound is associated with the topology of the mesh and with the constraints imposed by the boundary of the domain. To solve this problem, we propose in this work to combine the tetrahedral mesh optimization technique introduced in (1,2) with the local mesh refinem...

The efficiency of a mass consistent model for wind field adjustment depends on several parameters that arise in various stages of the process. On one hand, those involved in the construction of the initial wind field using horizontal interpolation and vertical extrapo- lation of the wind measures registered at meteorological stations. On the other...

This paper presents a new procedure to improve the quality of triangular meshes defined on surfaces. The improvement is obtained
by an iterative process in which each node of the mesh is moved to a new position that minimizes certain objective function.
This objective function is derived from an algebraic quality measures of the local mesh (the set...

The data structures used to model meshes for solving problems by finite element methods is based on different arrays. In these arrays information is stored related to, among other components, nodes, edges, faces, tetrahedra and connectivities. These structures provide optimum results but, in many cases, they need additional programming to be mainta...

Air pollution models usually start from the computation of the velocity field of a fluid. In this paper, we present a model
for computing that field based on the contribution of the observed wind flow and the vertical buoyancy or momentum plume rise
defined by a Gaussian plume model. This initial velocity field is adjusted to verify incompressibili...

Air pollution models usually start from the computation of the velocity field of the fluid. In this paper, we present a model for computing such a field based on the contribution of the observed wind flow and the vertical buoyancy or momentum plume rise defined by a Gaussian plume model. This initial velocity field is adjusted to verify incompressi...

To solve problems using finite element method it is necessary to obtain a good domain discretization. Once the problem geometry has been approached by an initial mesh, it must be able to adapt itself to the singularities of the numerical solution. The refinement process introduces new elements in zones of the mesh where the solution needs to be imp...

The quality improvement in mesh optimisation techniques that preserve its connectivity are obtained by an iterative process in which each node of the mesh is moved to a new position that minimises a certain objective function. The objective function is derived from some quality measure of the local submesh, that is, the set of tetrahedra connected...

The quality improvement in mesh optimisation techniques that preserve its connectivity are obtained by an iterative process in which each node of the mesh is moved to a new position that minimises a certain objective function. In general, objective functions are derived from some quality measure of the local submesh, that is, the set of tetrahedra...

En la simulación con el método de elementos finitos de procesos que tienen lugar en un dominio tridimensional
definido sobre un terreno de orografía irregular es fundamental disponer de un mallador que se adapte
a las características topográficas. El objetivo de este trabajo es desarrollar un código capaz de generar
automáticamente una malla de tet...

The quality improvement in mesh optimisation techniques that preserve its connectivity are obtained by an iterative process in which each node of the mesh is moved to a new position that minimises a certain objective function. In general, objective functions are derived from some quality measure of the local submesh, that is, the set of tetrahedra...

The efficiency of a mass consistent model for wind field adjustment depends on several parameters that arise in various stages
of the process. First, those involved in the construction of the initial wind field using horizontal interpolation and vertical
extrapolation of the wind measures registered at meteorological stations. On the other hand, th...

In the finite element simulation of environmental processes that occur in a three-dimensional domain defined over an irregular terrain, a mesh generator capable of adapting itself to the topographic characteristics is essen tial. The present study develops a code for generating a tetrahedral mesh from an "optimal" node distribution in the domain. T...

In the FEM simulation of processes that occur in a three-dimensional domain defined over an irregular terrain, it is fundamental to have a mesh generator being capable of adapting itself to the topographic characteristics. The objective of this work is to develop a code able to generate a tetrahedral mesh from an "optimal" node distribution in the...

The data structures used to model meshes for solving problems by finite element methods is based on different arrays. In these arrays information is stored related to, among other components, nodes, edges, faces, tetrahedral and connectivity. These structures provide optimum results which, in many cases, incur additional programming. In adaptively...

A three-dimensional finite element model for wind field adjustment was made. In general, these problems were defined over regions with complex terrain, therefore a suitable discretization of the studied zone will be necessary. As such, a technique for constructing tetrahedral meshes which are adapted to the terrain orography and has a higher densit...

Palabras clave: Sistemas de ecuaciones lineales, Matrices variables, Gradiente Conjugado precondicionado, Inversa aproximada factorizada Resumen. Se plantea el precondicionamiento de sistemas de ecuaciones de la forma A ε x ε = b ε con A ε = M + εN simétrica definida positiva. Hay dos estrategias extremas para efectuar este precondicionamiento. Com...

The objective of this work is to present our recent results in the numerical solution of a mass consistent wind field model, which could be also introduced in an air pollution model. We summarize the evaluation of the wind field based on the contribution of the observed wind flow. Besides, this mass consistent model includes effects of chimney emis...

The efficiency of a mass consistent model for wind field adjustment depends on sev-eral parameters that arise in various stages of the process. On one hand, those involved in the construction of the initial wind field using hori-zontal interpolation and vertical extrapolation of the wind measures registered at meteorological stations. On the other...

Resumen. This paper presents a new procedure to improve the quality of triangular meshes defined on surfaces. The improvement is got by an iterative process in which each node of the mesh is moved to a new position that minimizes certain objective function. This objective function is derived from quality measures of the local mesh (the set of trian...

Resumen. This paper presents a new procedure to improve the quality of triangular meshes defined on surfaces. The improvement is obtained by an iterative process in which each node of the mesh is moved to a new position that minimizes certain objective function. This objective function is derived from an algebraic quality measures of the local mesh...

In environmental modeling (air pollution, wind field [1], etc.) that occurs in three-dimensional domains defined over complex terrains, a mesh generator capable of adapting itself to topographical data, to chimney geometry and to the numerical solution is essential. For this purpose, in past works we have developed an automatic unstructured tetrahe...

In the finite element simulation of environmental processes that occur in a three-dimensional domain defined over an irregular terrain, a mesh generator capable of adapting itself to the topographic characteristics and to the numerical solution is essential. The objective of this work is to present our recent results in these topics. We construct a...

In this work we focus our attention on two aspects related to the node movement in surface meshes: smoothing of trian-gular meshes defined on surfaces and the adaption of these meshes to match given curves or contours. The quality improvement of the mesh is obtained by an iterative process in which each node of the mesh is moved to a new position t...

Resumen En la simulación numérica de campos de viento existen tres aspectos prin-cipales que caracterizan a un modelo y que, en definitiva, definirán la eficiencia del mismo. En primer lugar, debemos ser capaces de generar mallas tridimen-sionales que se adapten a dominios definidos sobre una orografía irregular. Asimismo, necesitamos más concentra...

In this paper we present new ideas and applications of an innovative tetra-hedral mesh generator which was introduced in [1, 2]. This automatic mesh generation strategy uses no Delaunay triangulation, nor advancing front technique, and it simplifies the geometrical discretization problem in particular cases. The main idea of the new mesh generator...

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