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This paper presents a study of the characteristics of rainfall in a typical Mediterranean climate, characterized by infrequent and irregular rain in the territorial area and its intensity. One of the main components of this type of climate is short-duration and high-intensity rain events that cause a large amount of damage to property and human lives, seriously affecting the operation of infrastructure and the activity of society in general. The objective of this study was to design a methodology based on peak over threshold (POT) analysis. This methodology allows us to establish reference precipitation values and more approximate return periods in the absence of sufficiently extensive historical precipitation series. In addition, the frequency of these extreme events or return periods is established. The characteristics of the precipitation regime make direct analysis difficult. Thus, the functions of the probability distributions underlying the described phenomena are improved.
Ramón Egea Pérez; Mónica Cortés-Molina; Francisco Navarro-González. Analysis of Rainfall Time Series with Application to Calculation of Return Periods. Sustainability 2021, 13, 8051 .
AMA StyleRamón Egea Pérez, Mónica Cortés-Molina, Francisco Navarro-González. Analysis of Rainfall Time Series with Application to Calculation of Return Periods. Sustainability. 2021; 13 (14):8051.
Chicago/Turabian StyleRamón Egea Pérez; Mónica Cortés-Molina; Francisco Navarro-González. 2021. "Analysis of Rainfall Time Series with Application to Calculation of Return Periods." Sustainability 13, no. 14: 8051.
This paper presents a study on the optimization problem of a consumer’s choice constrained to a single time interval. In this problem, the choice is made over a set of perishable goods such that they do not retain value at the end of the period. Money has been introduced as the only means available to store that value for the future. Thus, consumer utility is measured on the possible combinations of goods consumed during the period and money held at the end of the period. Additionally, a set of simple conditions are assumed to the utility functions for goods and money given by: (1) Existence of a total utility that is additively separable with respect to the components of goods and money; (2) continuity of the derivatives of the utility functions of money and goods up to the second degree; and (3) non-uniqueness of the matrix obtained by differentiating the system of equations obtained by the condition of optimum. The article shows how the requirement of homogeneity conditions limits the possible expressions for the utility function of money. One of them is the frequently used logarithmic function.
Francisco Navarro-González; Yolanda Villacampa. A Foundation for Logarithmic Utility Function of Money. Mathematics 2021, 9, 665 .
AMA StyleFrancisco Navarro-González, Yolanda Villacampa. A Foundation for Logarithmic Utility Function of Money. Mathematics. 2021; 9 (6):665.
Chicago/Turabian StyleFrancisco Navarro-González; Yolanda Villacampa. 2021. "A Foundation for Logarithmic Utility Function of Money." Mathematics 9, no. 6: 665.
The Pampas region is characterized by a high complexity in its productive system planning and faces the challenge of satisfying future food demands, as well as reducing the environmental impact of the activity. Climate change affects crops and farmers should use species capable of adapting to the changed climate. Among these species, faba bean (Vicia faba L.) cv. ‘Alameda’ has shown good adaptation to weather variability and, as a winter legume, it can help maintain the sustainability of agricultural systems in the area. The main purpose of this research was to select the models which describe the production characteristics of the ‘Alameda’ bean by using the least number of variables. Experimental and agrometeorological data from the cultivation of the ‘Alameda’ in Azul, Buenos Aires province, Argentina were used to generate mathematical models. Several modelling methodologies have been applied to study the production characteristics of the faba bean. The prediction of the models generated was analyzed by randomly disturbing the experimental data and analyzing the magnitude of the errors produced. The models obtained will be useful for predicting the biomass production of the faba bean cv. ‘Alameda’ grown in the agroclimatic conditions of Azul, Buenos Aires province, Argentina.
Yolanda Villacampa; Francisco Navarro-González; Gabriela Hernández; Juan Laddaga; Adriana Confalone. Modelling Faba Bean (Vicia faba L.) Biomass Production for Sustainability of Agricultural Systems of Pampas. Sustainability 2020, 12, 9829 .
AMA StyleYolanda Villacampa, Francisco Navarro-González, Gabriela Hernández, Juan Laddaga, Adriana Confalone. Modelling Faba Bean (Vicia faba L.) Biomass Production for Sustainability of Agricultural Systems of Pampas. Sustainability. 2020; 12 (23):9829.
Chicago/Turabian StyleYolanda Villacampa; Francisco Navarro-González; Gabriela Hernández; Juan Laddaga; Adriana Confalone. 2020. "Modelling Faba Bean (Vicia faba L.) Biomass Production for Sustainability of Agricultural Systems of Pampas." Sustainability 12, no. 23: 9829.
Solar energy is one of the most promising green energy sources. On-grid photovoltaic installations supply energy to consumers as a support energy source, but in isolated areas, it comes as the unique source. The decision-maker must dimension the installation, maintaining system performance with reasonable investments. In some scenarios, the utility manager can handle the energy delivered to consumers as every subsystem can be independently connected. A strategy for scheduling the energy consumption to decrease the number of photovoltaic modules required in a standalone system is proposed here. The problem formulation corresponds to generalising a more specific problem before published. We presented a real case study being the groups of hydrants that provide water to crops in a pressurized irrigation system for energy consumption to schedule.
Francisco J. Navarro-Gonzalez; Yolanda Villacampa; Miguel Ángel Pardo Picazo; M. Cortés-Molina. Optimal load scheduling for off-grid photovoltaic installations with fixed energy requirements and intrinsic constraints. Process Safety and Environmental Protection 2020, 149, 476 -484.
AMA StyleFrancisco J. Navarro-Gonzalez, Yolanda Villacampa, Miguel Ángel Pardo Picazo, M. Cortés-Molina. Optimal load scheduling for off-grid photovoltaic installations with fixed energy requirements and intrinsic constraints. Process Safety and Environmental Protection. 2020; 149 ():476-484.
Chicago/Turabian StyleFrancisco J. Navarro-Gonzalez; Yolanda Villacampa; Miguel Ángel Pardo Picazo; M. Cortés-Molina. 2020. "Optimal load scheduling for off-grid photovoltaic installations with fixed energy requirements and intrinsic constraints." Process Safety and Environmental Protection 149, no. : 476-484.
Estimation problems are frequent in several fields such as engineering, economics, and physics, etc. Linear and non-linear regression are powerful techniques based on optimizing an error defined over a dataset. Although they have a strong theoretical background, the need of supposing an analytical expression sometimes makes them impractical. Consequently, a group of other approaches and methodologies are available, from neural networks to random forest, etc. This work presents a new methodology to increase the number of available numerical techniques and corresponds to a natural evolution of the previous algorithms for regression based on finite elements developed by the authors improving the computational behavior and allowing the study of problems with a greater number of points. It possesses an interesting characteristic: Its direct and clear geometrical meaning. The modelling problem is presented from the point of view of the statistical analysis of the data noise considered as a random field. The goodness of fit of the generated models has been tested and compared with some other methodologies validating the results with some experimental campaigns obtained from bibliography in the engineering field, showing good approximation. In addition, a small variation on the data estimation algorithm allows studying overfitting in a model, that it is a problematic fact when numerical methods are used to model experimental values.
Francisco José Navarro-González; Yolanda Villacampa; Mónica Cortés-Molina; Salvador Ivorra. Numerical Non-Linear Modelling Algorithm Using Radial Kernels on Local Mesh Support. Mathematics 2020, 8, 1600 .
AMA StyleFrancisco José Navarro-González, Yolanda Villacampa, Mónica Cortés-Molina, Salvador Ivorra. Numerical Non-Linear Modelling Algorithm Using Radial Kernels on Local Mesh Support. Mathematics. 2020; 8 (9):1600.
Chicago/Turabian StyleFrancisco José Navarro-González; Yolanda Villacampa; Mónica Cortés-Molina; Salvador Ivorra. 2020. "Numerical Non-Linear Modelling Algorithm Using Radial Kernels on Local Mesh Support." Mathematics 8, no. 9: 1600.
System modeling is a main task in several research fields. The development of numerical models is of crucial importance at the present because of its wide use in the applications of the generically named machine learning technology, including different kinds of neural networks, random field models, and kernel-based methodologies. However, some problems involving the reliability of their predictions are common to their use in the real world. Octahedric regression is a kernel averaged methodology developed by the authors that tries to simplify the entire process from raw data acquisition to model generation. A discussion about the treatment and prevention of overfitting is presented and, as a result, models are obtained that allow for the measurement of this effect. In this paper, this methodology is applied to the problem of estimating the energetic needs of different buildings according to their principal characteristics, a problem that has importance in architecture and civil and environmental engineering due to increasing concerns about energetic efficiency and ecological footprint.
Francisco J. Navarro-Gonzalez; Yolanda Villacampa. An Octahedric Regression Model of Energy Efficiency on Residential Buildings. Applied Sciences 2019, 9, 4978 .
AMA StyleFrancisco J. Navarro-Gonzalez, Yolanda Villacampa. An Octahedric Regression Model of Energy Efficiency on Residential Buildings. Applied Sciences. 2019; 9 (22):4978.
Chicago/Turabian StyleFrancisco J. Navarro-Gonzalez; Yolanda Villacampa. 2019. "An Octahedric Regression Model of Energy Efficiency on Residential Buildings." Applied Sciences 9, no. 22: 4978.
The erosion of the world's coasts and the shortage of sand to mitigate beach erosion are leading to the increasingly common use of gravel for coastal protection and beach nourishment. Therefore, in order to determine the amount of gravel required for such actions, it is important to know perfectly the equilibrium profile of gravel beaches. However, at present, this profile is obtained from formulas obtained mainly after channel tests, and therefore most of them do not adapt to the real profiles formed by gravel beaches in nature. In this article, 31 variables related to sedimentology, waves, morphology and marine vegetation present on the beaches are studied to determine which are the most influential in the profile. From the study carried out, it is obtained that these variables are the steepness and probability of occurrence of the wave perpendicular to the coast, the profile starting slope (between MWL and -2m), the energy reduction coefficient due to Posidonia oceanica as well as the width of the meadow. Using these variables, different numerical models were generated to predict accurately the gravel beach profile, which will lead to a saving in the volume of material used in the order of 1300m(3)/ml of beach with respect to current formulations, and a greater certainty that the beach nourishment carried out will have the desired effect.
I. López; Luis Aragonés; Y. Villacampa; F.J. Navarro-González. Gravel beaches nourishment: Modelling the equilibrium beach profile. Science of The Total Environment 2018, 619-620, 772 -783.
AMA StyleI. López, Luis Aragonés, Y. Villacampa, F.J. Navarro-González. Gravel beaches nourishment: Modelling the equilibrium beach profile. Science of The Total Environment. 2018; 619-620 ():772-783.
Chicago/Turabian StyleI. López; Luis Aragonés; Y. Villacampa; F.J. Navarro-González. 2018. "Gravel beaches nourishment: Modelling the equilibrium beach profile." Science of The Total Environment 619-620, no. : 772-783.
Monitoring of the quality of bathing water in line with the European Commission bathing water directive (Directive 2006/7/EC) is a significant economic expense for those countries with great lengths of coastline. In this study a numerical model based on finite elements is generated whose objective is partially substituting the microbiological analysis of the quality of coastal bathing waters. According to a study of the concentration of Escherichia coli in 299 Spanish Mediterranean beaches, it was established that the most important variables that influence the concentration are: monthly sunshine hours, mean monthly precipitation, number of goat cattle heads, population density, presence of Posidonia oceanica, UV, urbanization level, type of sediment, wastewater treatment ratio, salinity, distance to the nearest discharge, and wave height perpendicular to the coast. Using these variables, a model with an absolute error of 10.6±1.5CFU/100ml is achieved. With this model, if there are no significant changes in the beach environment and the variables remain more or less stable, the concentration of E. coli in bathing water can be determined, performing only specific microbiological analyses to verify the water quality.
A. Palazón; I. López; L. Aragonés; Y. Villacampa; F.J. Navarro-González. Modelling of Escherichia coli concentrations in bathing water at microtidal coasts. Science of The Total Environment 2017, 593-594, 173 -181.
AMA StyleA. Palazón, I. López, L. Aragonés, Y. Villacampa, F.J. Navarro-González. Modelling of Escherichia coli concentrations in bathing water at microtidal coasts. Science of The Total Environment. 2017; 593-594 ():173-181.
Chicago/Turabian StyleA. Palazón; I. López; L. Aragonés; Y. Villacampa; F.J. Navarro-González. 2017. "Modelling of Escherichia coli concentrations in bathing water at microtidal coasts." Science of The Total Environment 593-594, no. : 173-181.
Luis Aragonés; Y. Villacampa; F.J. Navarro-González; I. López. Numerical modelling of the equilibrium profile in Valencia (Spain). Ocean Engineering 2016, 123, 164 -173.
AMA StyleLuis Aragonés, Y. Villacampa, F.J. Navarro-González, I. López. Numerical modelling of the equilibrium profile in Valencia (Spain). Ocean Engineering. 2016; 123 ():164-173.
Chicago/Turabian StyleLuis Aragonés; Y. Villacampa; F.J. Navarro-González; I. López. 2016. "Numerical modelling of the equilibrium profile in Valencia (Spain)." Ocean Engineering 123, no. : 164-173.
F.J. Navarro-González; Y. Villacampa; Carlos A. Brebbia; Willy Patrick De Wilde; Giovanni Carlomagno. A finite element numerical algorithm for modelling and data fitting in complex systems. International Journal of Computational Methods and Experimental Measurements 2016, 4, 100 -113.
AMA StyleF.J. Navarro-González, Y. Villacampa, Carlos A. Brebbia, Willy Patrick De Wilde, Giovanni Carlomagno. A finite element numerical algorithm for modelling and data fitting in complex systems. International Journal of Computational Methods and Experimental Measurements. 2016; 4 (2):100-113.
Chicago/Turabian StyleF.J. Navarro-González; Y. Villacampa; Carlos A. Brebbia; Willy Patrick De Wilde; Giovanni Carlomagno. 2016. "A finite element numerical algorithm for modelling and data fitting in complex systems." International Journal of Computational Methods and Experimental Measurements 4, no. 2: 100-113.
The eigenvalues and eigenvectors of a matrix have many applications in engineering and science. For example they are important in studying and solving structural problems, in the treatment of signal or image processing, in the study of quantum mechanics and in certain physical problems. It is therefore essential to analyze methodologies to obtain the eigenvectors and eigenvalues of symmetric and Hermitian matrices. In this paper the authors present a methodology for obtaining the eigenvectors and eigenvalues of a symmetric or Hermitian matrix using a genetic algorithm. Unlike other methodologies, the process is centred in searching the eigenvectors and calculating the eigenvalues afterwards. In the search of the eigenvectors a genetic-based algorithm is used. Genetic algorithms are indicated when the search space is extended, unknown or with an intricate geometry. Also, the target vector space can be either real or complex, allowing in this way a wider field of application for the proposed method. The algorithm is tested comparing the results with those obtained by other methods or with the values previously known. So, seven applications are included: a real symmetric matrix corresponding to a vibrating system, a complex Hermitian matrix and an important application of the diagonalization problem (Coope matrix) corresponding to quantum mechanics examples, a physical problem in which data are analysed to reduce the number of variables, a comparison with the power method and the studies of a degenerate and an ill-conditioned matrix.
F.J. Navarro-González; P. Compañ; R. Satorre; Y. Villacampa. Numerical determination for solving the symmetric eigenvector problem using genetic algorithm. Applied Mathematical Modelling 2016, 40, 4935 -4947.
AMA StyleF.J. Navarro-González, P. Compañ, R. Satorre, Y. Villacampa. Numerical determination for solving the symmetric eigenvector problem using genetic algorithm. Applied Mathematical Modelling. 2016; 40 (7-8):4935-4947.
Chicago/Turabian StyleF.J. Navarro-González; P. Compañ; R. Satorre; Y. Villacampa. 2016. "Numerical determination for solving the symmetric eigenvector problem using genetic algorithm." Applied Mathematical Modelling 40, no. 7-8: 4935-4947.
In this article, a new methodology is presented to obtain representation models for a priori relation z = u(x1, x2, . . . ,xn) (1), with a known an experimental dataset zi; x1i ; x2i ; x3i ; . . . ; xni i=1;2;...;p· In this methodology, a potential energy is initially defined over each possible model for the relationship (1), what allows the application of the Lagrangian mechanics to the derived system. The solution of the Euler–Lagrange in this system allows obtaining the optimal solution according to the minimal action principle. The defined Lagrangian, corresponds to a continuous medium, where a n-dimensional finite elements model has been applied, so it is possible to get a solution for the problem solving a compatible and determined linear symmetric equation system. The computational implementation of the methodology has resulted in an improvement in the process of get representation models obtained and published previously by the authors
F.J. Navarro-González; Y. Villacampa. Generation of representation models for complex systems using Lagrangian functions. Advances in Engineering Software 2013, 64, 33 -37.
AMA StyleF.J. Navarro-González, Y. Villacampa. Generation of representation models for complex systems using Lagrangian functions. Advances in Engineering Software. 2013; 64 ():33-37.
Chicago/Turabian StyleF.J. Navarro-González; Y. Villacampa. 2013. "Generation of representation models for complex systems using Lagrangian functions." Advances in Engineering Software 64, no. : 33-37.
In this article a new methodology is developed, for the modelling of complex systems where the number of variables and relationships can be high. This methodology allows an efficient work on a n-dimensional hypercube and its computational implementation, a fact that was not possible through a generalisation of the 2-dimensional methodology developed in [10]. The methodology allows obtaining representation models of a function or relationship, z = u(x1, x2, …… , xn) obtained from the interpolation defined in an n-dimensional finite element model. The interpolation function implies the use of some initial conditions, what in the defined methodology implies the coincidence between the values of the function in a finite number of points zi,xi1,xi2,xi3,……,xini=1,.2,…,p. As usually when a finite element model of representation is used, the function is obtained in a finite set of points, called nodes [22]. In this case, this is done by solving an optimisation problem based on the search of the minimum of an error function defined generically in any finite element model defined in the hypercube. The computational implementation of the methodology allows obtaining families of mathematical models that represent the relationships. From each obtained model several information parameters are also considered, as roughness and stability.
F.J. Navarro-González; Y. Villacampa. A new methodology for complex systems using n-dimensional finite elements. Advances in Engineering Software 2012, 48, 52 -57.
AMA StyleF.J. Navarro-González, Y. Villacampa. A new methodology for complex systems using n-dimensional finite elements. Advances in Engineering Software. 2012; 48 ():52-57.
Chicago/Turabian StyleF.J. Navarro-González; Y. Villacampa. 2012. "A new methodology for complex systems using n-dimensional finite elements." Advances in Engineering Software 48, no. : 52-57.
Y. Villacampa; F. J. Navarro-González; J. Llorens. A geometric model for the generation of models defined in Complex Systems. Ecosytems and Sustainable Development VII 2009, 122, 71 -82.
AMA StyleY. Villacampa, F. J. Navarro-González, J. Llorens. A geometric model for the generation of models defined in Complex Systems. Ecosytems and Sustainable Development VII. 2009; 122 ():71-82.
Chicago/Turabian StyleY. Villacampa; F. J. Navarro-González; J. Llorens. 2009. "A geometric model for the generation of models defined in Complex Systems." Ecosytems and Sustainable Development VII 122, no. : 71-82.