# Cesar OmarUniversity of Oviedo | UNIOVI · Department of Mathematics

Cesar Omar

Mining Engineering

## About

30

Publications

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593

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Introduction

Additional affiliations

October 1983 - April 2016

October 1983 - April 2016

October 1983 - April 2016

## Publications

Publications (30)

We present a Galerkin method based on the combination of a mixed finite element method and a spectral boundary element method to solve an exterior second order elliptic boundary value problem. we prove that the scheme is stable with respect to the discretization parameters and derive optimal a priori error estimates.

This review has two main parts. The first of them presents existing ideas and data related to recumbent folds, reviewing aspects such as the physical conditions of the development of these folds, the strain inside the folded layers, the kinematic mechanisms of their formation, the role of gravitational forces, the tectonic context of their developm...

Folding during the Variscan deformation in NW Iberia has been analysed from the foreland to the hinterland of the orogen using several geometrical techniques complemented by the numerical simulation of kinematical folding mechanisms with the aid of a computer program (‘FoldModeler’). In the foreland, folds are related to thrusts; in the inner zones...

Mathematical 2D modelling of asymmetric folds is carried out by applying a combination of different kinematic folding mechanisms: tangential longitudinal strain, flexural flow and homogeneous deformation. The main source of fold asymmetry is discovered to be due to the superimposition of a general homogeneous deformation on buckle folds that typica...

PSO is an optimization technique inspired by the social behavior of individuals in nature (swarms) that has been successfully used in many different engineering fields. In addition, the PSO algorithm can be physically interpreted as a stochastic damped mass–spring system. This analogy has served to introduce the PSO continuous model and to deduce a...

Vertical electrical soundings (VES) is a low-cost geophysical method very well suited to the analysis and monitoring of salt-water intrusion problems, since this interface generates a low resistivity anomaly. One major drawback of all geophysical inverse problems is that they are ill-posed: the objective function has its minimum in a flat elongated...

Geophysical inverse problems are ill‐posed: the objective function has its minimum in a flat elongated valley or surrounded by many local minima. Local optimization methods give unpredictable results if no prior information is available. Traditionally this has generated mistrust on the use of geophysical inverse methods (equivalence problem in VES)...

PSO is a stochastic optimization technique that has been successfully used in many different engineering fields. PSO algorithm can be physically interpreted as a stochastic damped mass-spring system (Fernandez Martinez and Garcia Gonzalo 2008). Based on this analogy we present a whole family of PSO algorithms and their respective first order and se...

DC resistivity inverse problems are ill-posed. For the Vertical Electrical Sounding method the acceptable solutions lie in
very narrow elongated-shape regions in the model space. To characterize this ensemble of solutions is a central question.
In a Bayesian framework this issue is solved adopting as solution the so-called model posterior probabili...

PSO is an optimization technique that has been successfully used in many different engineering fields. The PSO algorithm can be physically interpreted as a stochastic damped mass-spring system. This analogy served us to introduce the PSO continuous model and to deduce a whole family of PSO algorithms arising from the discretization of the PSO conti...

Most of the geophysical inverse problems are ill-posed. In the VES (Vertical Electrical Sounding) case this fact is known as the equivalence or suppression problem: the shape of the objective function is that of the bottom of a narrow, elongated valley with almost null gradients and many localized "sinkholes". Flat outer areas with ridges also prev...

El problema inverso asociado a los Sondeos Eléctricos Verticales es un problema mal planteado en el sentido de que pequeñas perturbaciones en las observaciones de campo (errores de medida) se propagan hacia la solución del problema modificándola de modo importante. La interpretación tradicional del problema inverso como problema de estimación de pa...

The vertical Electrical Sounding problem is ill posed. Small data disturbances propagate backwards and contaminate notably the solution. Classical interpretation of the inverse problem as a parameter estimation case searches for a unique model. Yet, many models -known as equivalent models- are able to fit data equally well. Local optimization techn...

FOLD PROFILER is a MATLAB code for classifying the shapes of profiles of folded surfaces. The classification is based on the comparison of the natural fold profile with curves representing mathematical functions. The user is offered a choice of four methods, each based on a different type of function: cubic Bezier curves, conic sections, power func...

The use of an ion exchange resin in the recovery of copper cyanide complexes from wastewater and the recycling of the cyanide used in cyanidation to the gold cyanidation step is an economically interesting process. The equilibrium and kinetics in the loading stage using a strong base resin, Bayer Lewatit MP500, have been studied in this work. Two t...

This work will focus on data provided by a field Vertical Electrical Sounding (VES) survey over a coastal aquifer in South Spain, where sea water intrusion is known to be a major problem. The VES inverse problem is nonlinear and ill posed. In a deterministic framework this means that small variations in data translate into non negligible random alt...

In this paper we present the application of binary genetic algorithms to the solution and analysis of the Vertical Electrical Sounding (VES) inverse problem. The goal of this technique is to estimate the resistivities and thicknesses of the strata in a multilayered earth, this having important environmental applications. In the inverse problem mode...

Tomography methods belong to the class of non destructive inspection techniques and are widely used in engineering applications. One of the main disadvantages of these methods is their data dependence, since data errors are often present in transmission tomography experiments. These errors are propagated to the model parameters and are responsible...

In this article we present a geostatistical approach to the transmission tomographic inverse problem, which is based on consideration of the inverse problem variables (velocity and traveltime errors) as regionalized variables (R.V.). Their structural analysis provides us with a new method to study the geophysical anisotropy of the rock, an importan...

In statistics, Box-Jenkins Time Series is a linear method widely used to forecasting. The linearity makes the method inadequate
to forecast real time series, which could present irregular behavior. On the other hand, in artificial intelligence FeedForward
Artificial Neural Networks and Continuous Machine Learning Systems are robust handlers of data...

This paper presents the forecasting of the thermal performance of a seawater refrigerated power plant condenser subject to tide effects. The thermal performance is evaluated by the values of the heat transfer rate (Q), of the overall heat transfer coefficient (U) and of the cleanliness factor (FC). To obtain these variables, non-fully connected neu...

This paper presents a model that uses non-fully connected Feedforward Artificial Neural Networks (FANNs) for the forecasting of a seawater-refrigerated power plant condenser performance using the heat transfer rate (Q̇), the heat transfer coefficient (U) and the cleanliness factor (FC). The model developed includes FANNs that take into account the...

We present a numerical method for solving an exterior Dirichlet problem in the plane. The technique consists in coupling boundary integral and mixed finite element methods. An artificial boundary is introduced separating an interior region from an exterior one. From an integral representation of the solution in the exterior domain we deduce two int...

We apply the coupling of the boundary integral method and the finite element method to solve a nonlinear problem in the plane. Specifically the boundary value problem consists of a second-order quasilinear problem in divergence form in a bounded inner region and the Laplace equation in the corresponding unbounded exterior region, in addition to app...