R. Saldanha | UFMG - The Federal University of Minas Gerais (original) (raw)
Papers by R. Saldanha
IEE Proceedings - Generation, Transmission and Distribution, 2005
A hybrid algorithm combines a quasi-Newton and a genetic algorithm for the optimal expansion of e... more A hybrid algorithm combines a quasi-Newton and a genetic algorithm for the optimal expansion of energy distribution systems. The quasi-Newton procedure actuates in the search for optimal substation location coordinates , and the genetic algorithm procedure actuates in the design of optimal network topologies. Both searches are performed jointly in the proposed methodology. The costs of facility installation, maintenance and energy losses are considered. The algorithm has been applied in a real energy distribution system expansion problem.
IEEE Transactions on Magnetics, 2006
Resumo-Este artigo apresenta uma configuração modificada de Algoritmos Genéticos com codificação ... more Resumo-Este artigo apresenta uma configuração modificada de Algoritmos Genéticos com codificação real e utilizando cruzamento polarizado e mutação pelo comportamento da população, ambos por variável. Ela será aplicada na modelagem da forma do refletor com abertura circular de uma Antena Refletora Offset na busca do melhor diagrama de radiação para a área de cobertura do território brasileiro. A análise da antena é feita com a aproximação de ótica física corrigida por correntes equivalentes de borda. É realizada também uma breve discussão sobre codificação binária e real em Algoritmos Genéticos.
TEMA - Tendências em Matemática Aplicada e Computacional, 2002
Resumo: O uso de conhecimento a priori em identificação de sistemas como ferramenta auxiliar para... more Resumo: O uso de conhecimento a priori em identificação de sistemas como ferramenta auxiliar para a melhoria da estrutura e para a estimação de parâmetros vem se destacando nosúltimos anos. Com esse propósito, o presente trabalho parte das definições gerais em identificação caixa-preta (sem uso de conhecimento a priori) e das características gerais da estrutura dos modelos NARX polinomiais para definir uma metodologia que permita usar conhecimento a priori nas etapas de escolha de estrutura e estimação de parâmetros utilizando ferramentas de otimização. Em geral, os modelos identificados fazendo-se uso de informação a priori têm um comportamento global melhor de que seus análogos obtidos por técnicas caixa-preta. Para ilustrar este fato será mostrado um exemplo utilizando-se dados medidos reais de um conversor CC-CC Buck.
IEEE Transactions on Magnetics, 2004
This paper presents Optimise, a computational optimization environment tool for education in elec... more This paper presents Optimise, a computational optimization environment tool for education in electrical engineering. Optimise has been developed using software engineering process and object-oriented programming philosophy. This educational tool incorporates a set of deterministic and stochastic methods and also a set of computational intelligence techniques. Optimise offers a friendly interface that allows the students to practice the theory learned, and also to verify and compare the features of the optimization methods. A general view of the software is presented, describing its modules and class libraries. Some optimization problems are discussed to illustrate the flexibility and power of Optimise as an educational tool.
IEEE Transactions on Magnetics, 1996
The optimal design of a ridged waveguide is considered in this paper. The geometric shape of the ... more The optimal design of a ridged waveguide is considered in this paper. The geometric shape of the waveguide is computed so that two prescribed lowest modes of the transverse magnetic fields are obtained. A general formulation of the problem is presented: the electromagnetic problem i s solved by a finite-difference scheme, and the Ellipsoid and the Tabu Search Algorithms are used to solve the optimization problem. This formulation should enable the design of guides to meet most practical specifications. Some computational results are given.
We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a ... more We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase Liquid Argon Time Projection Chamber (LAr-TPC) to a low energy pulsed narrowband neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.2 keV and for applied electric fields from 0 to 1000 V/cm. For the ionization yields, we report measurements from 16.9 to 57.2 keV and for electric fields from 50 to 500 V/cm. We also report the observation of an anti-correlation between scintillation and ionization from nuclear recoils, which is similar to the anti-correlation between scintillation and ionization from electron recoils. Assuming that the energy partition in excitons and ion pairs of 83m Kr internal conversion electrons is comparable to that of 207 Bi conversion electrons, we obtained the numbers of excitons (N ex) and ion pairs (N i) and their ratio (N ex /N i) produced by nuclear recoils from 16.9 to 57.2 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.
Journal of Magnetism and Magnetic Materials, 1991
The principle of the actuator is the force applied on a magnet located in a gradient of magnetic ... more The principle of the actuator is the force applied on a magnet located in a gradient of magnetic field. An original force expression has been developed and used to optimize the structure in order to obtain a force which is constant along a given displacement. The penalty method is applied.
IEE Proceedings - Control Theory and Applications, 2004
The authors present a procedure that permits the use of steady-state information to constrain the... more The authors present a procedure that permits the use of steady-state information to constrain the identification of nonlinear polynomial models. Such a procedure has three main steps. First, a general framework is provided that relates the static function of nonlinear global polynomial models to their terms and parameters. Second, using standard nonlinear programming techniques, a rational function is fitted to the system static function, which is assumed to be known and is used as auxiliary information. Finally, the information gathered in the first two steps is used to write a set of equality constraints that are exactly satisfied by a standard constrained least-squares algorithm used to estimate the parameters of the identified model. It is shown that the resulting model will always have the specified static nonlinearity and will use additional degrees of freedom to fit the dynamics underlying the observed data.
IEEE Transactions on Magnetics, 1993
A time domain finite element method (TDFE) applied to the analysis of electrical transients on lo... more A time domain finite element method (TDFE) applied to the analysis of electrical transients on lossy transmission lines is presented. In this method, the general telegraph equations are solved numerically at discrete time steps. Examples of voltage waveforms on lossy single-phase lines are shown.
A meshless method for electromagnetic field computation is developed based on the multiquadric in... more A meshless method for electromagnetic field computation is developed based on the multiquadric interpolation technique. A global approximation to the solution is built based only on the discretization of the domain in nodes and the differential equations describing the problem in the domain and its boundary. An attractive characteristic of the multiquadric solution is that it is continuous and it has infinitely continuous derivatives. This is particularly important to obtain field quantities in electromagnetic analysis. The method is also capable of dealing with physical discontinuities present at the interface between different materials. The formulation is presented in the Cartesian and polar coordinates, which can be extended to other systems. We applied the formulation in the analysis of an electrostatic micromotor and a microstrip. The results demonstrate good agreement with other numerical technique, showing the adequacy of the proposed methodology for electromagnetic analysis.
... Antônio Carlos, 6627, Belo Horizonte, MG, Brasil mauricio.souza@pq.cnpq.br 4 Departamento de ... more ... Antônio Carlos, 6627, Belo Horizonte, MG, Brasil mauricio.souza@pq.cnpq.br 4 Departamento de Engenharia Elétrica, Universidade Federal de Minas Gerais, Av. ... The authors are grateful to Thiago Ferreira de Noronha, the coauthor of [7,8], for pro-viding datasets used. ...
This chapter is devoted to optimization formulations of satellite coverage problems and their sol... more This chapter is devoted to optimization formulations of satellite coverage problems and their solution. They are specially useful in satellite broadcasting applications, where the information goes from one to many. Due to distance from target and power supply constraints, highly directive efficient reflector antennas are the best choice. There are many possible optimization formulations for this problem, depending fundamentally on specifications and degrees of freedom in the system. Some specific coverage problems considering broadband, radiation pattern constraints and interference are presented, where the degrees of freedom are purely geometric.
This chapter is devoted to optimization formulations of satellite coverage problems and their sol... more This chapter is devoted to optimization formulations of satellite coverage problems and their solution. They are specially useful in satellite broadcasting applications, where the information goes from one to many. Due to distance from target and power supply constraints, highly directive efficient reflector antennas are the best choice. There are many possible optimization formulations for this problem, depending fundamentally on specifications and degrees of freedom in the system. Some specific coverage problems considering broadband, radiation pattern constraints and interference are presented, where the degrees of freedom are purely geometric.
Magnetics, IEEE …, Jan 1, 2004
Resumo -Este artigo apresenta uma configuração modificada de Algoritmos Genéticos com codificação... more Resumo -Este artigo apresenta uma configuração modificada de Algoritmos Genéticos com codificação real e utilizando cruzamento polarizado e mutação pelo comportamento da população, ambos por variável. Ela será aplicada na modelagem da forma do refletor com abertura circular de uma Antena Refletora Offset na busca do melhor diagrama de radiação para a área de cobertura do território brasileiro. A análise da antena é feita com a aproximação de ótica física corrigida por correntes equivalentes de borda. É realizada também uma breve discussão sobre codificação binária e real em Algoritmos Genéticos.
Page 1. Heuristique VND-ILS pour le Problème de Routage et d'Affectation de Longueur... more Page 1. Heuristique VND-ILS pour le Problème de Routage et d'Affectation de Longueur d'Onde Alexandre Xavier Martins1, Christophe Duhamel2, Philippe Mahey2, Maurício Cardoso de Souza3, Rodney Rezende Saldanha4 ...
Resumo: O uso de conhecimento a priori em identificação de sistemas como ferramenta auxiliar para... more Resumo: O uso de conhecimento a priori em identificação de sistemas como ferramenta auxiliar para a melhoria da estrutura e para a estimação de parâmetros vem se destacando nosúltimos anos. Com esse propósito, o presente trabalho parte das definições gerais em identificação caixa-preta (sem uso de conhecimento a priori ) e das características gerais da estrutura dos modelos NARX polinomiais para definir uma metodologia que permita usar conhecimento a priori nas etapas de escolha de estrutura e estimação de parâmetros utilizando ferramentas de otimização. Em geral, os modelos identificados fazendo-se uso de informação a priori têm um comportamento global melhor de que seus análogos obtidos por técnicas caixa-preta. Para ilustrar este fato será mostrado um exemplo utilizando-se dados medidos reais de um conversor CC-CC Buck.
... Antônio Carlos, 6627, Belo Horizonte, MG, Brasil mauricio.souza@pq.cnpq.br 4 Departamento de ... more ... Antônio Carlos, 6627, Belo Horizonte, MG, Brasil mauricio.souza@pq.cnpq.br 4 Departamento de Engenharia Elétrica, Universidade Federal de Minas Gerais, Av. ... The authors are grateful to Thiago Ferreira de Noronha, the coauthor of [7,8], for pro-viding datasets used. ...
IEE Proceedings - Generation, Transmission and Distribution, 2005
A hybrid algorithm combines a quasi-Newton and a genetic algorithm for the optimal expansion of e... more A hybrid algorithm combines a quasi-Newton and a genetic algorithm for the optimal expansion of energy distribution systems. The quasi-Newton procedure actuates in the search for optimal substation location coordinates , and the genetic algorithm procedure actuates in the design of optimal network topologies. Both searches are performed jointly in the proposed methodology. The costs of facility installation, maintenance and energy losses are considered. The algorithm has been applied in a real energy distribution system expansion problem.
IEEE Transactions on Magnetics, 2006
Resumo-Este artigo apresenta uma configuração modificada de Algoritmos Genéticos com codificação ... more Resumo-Este artigo apresenta uma configuração modificada de Algoritmos Genéticos com codificação real e utilizando cruzamento polarizado e mutação pelo comportamento da população, ambos por variável. Ela será aplicada na modelagem da forma do refletor com abertura circular de uma Antena Refletora Offset na busca do melhor diagrama de radiação para a área de cobertura do território brasileiro. A análise da antena é feita com a aproximação de ótica física corrigida por correntes equivalentes de borda. É realizada também uma breve discussão sobre codificação binária e real em Algoritmos Genéticos.
TEMA - Tendências em Matemática Aplicada e Computacional, 2002
Resumo: O uso de conhecimento a priori em identificação de sistemas como ferramenta auxiliar para... more Resumo: O uso de conhecimento a priori em identificação de sistemas como ferramenta auxiliar para a melhoria da estrutura e para a estimação de parâmetros vem se destacando nosúltimos anos. Com esse propósito, o presente trabalho parte das definições gerais em identificação caixa-preta (sem uso de conhecimento a priori) e das características gerais da estrutura dos modelos NARX polinomiais para definir uma metodologia que permita usar conhecimento a priori nas etapas de escolha de estrutura e estimação de parâmetros utilizando ferramentas de otimização. Em geral, os modelos identificados fazendo-se uso de informação a priori têm um comportamento global melhor de que seus análogos obtidos por técnicas caixa-preta. Para ilustrar este fato será mostrado um exemplo utilizando-se dados medidos reais de um conversor CC-CC Buck.
IEEE Transactions on Magnetics, 2004
This paper presents Optimise, a computational optimization environment tool for education in elec... more This paper presents Optimise, a computational optimization environment tool for education in electrical engineering. Optimise has been developed using software engineering process and object-oriented programming philosophy. This educational tool incorporates a set of deterministic and stochastic methods and also a set of computational intelligence techniques. Optimise offers a friendly interface that allows the students to practice the theory learned, and also to verify and compare the features of the optimization methods. A general view of the software is presented, describing its modules and class libraries. Some optimization problems are discussed to illustrate the flexibility and power of Optimise as an educational tool.
IEEE Transactions on Magnetics, 1996
The optimal design of a ridged waveguide is considered in this paper. The geometric shape of the ... more The optimal design of a ridged waveguide is considered in this paper. The geometric shape of the waveguide is computed so that two prescribed lowest modes of the transverse magnetic fields are obtained. A general formulation of the problem is presented: the electromagnetic problem i s solved by a finite-difference scheme, and the Ellipsoid and the Tabu Search Algorithms are used to solve the optimization problem. This formulation should enable the design of guides to meet most practical specifications. Some computational results are given.
We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a ... more We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase Liquid Argon Time Projection Chamber (LAr-TPC) to a low energy pulsed narrowband neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.2 keV and for applied electric fields from 0 to 1000 V/cm. For the ionization yields, we report measurements from 16.9 to 57.2 keV and for electric fields from 50 to 500 V/cm. We also report the observation of an anti-correlation between scintillation and ionization from nuclear recoils, which is similar to the anti-correlation between scintillation and ionization from electron recoils. Assuming that the energy partition in excitons and ion pairs of 83m Kr internal conversion electrons is comparable to that of 207 Bi conversion electrons, we obtained the numbers of excitons (N ex) and ion pairs (N i) and their ratio (N ex /N i) produced by nuclear recoils from 16.9 to 57.2 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.
Journal of Magnetism and Magnetic Materials, 1991
The principle of the actuator is the force applied on a magnet located in a gradient of magnetic ... more The principle of the actuator is the force applied on a magnet located in a gradient of magnetic field. An original force expression has been developed and used to optimize the structure in order to obtain a force which is constant along a given displacement. The penalty method is applied.
IEE Proceedings - Control Theory and Applications, 2004
The authors present a procedure that permits the use of steady-state information to constrain the... more The authors present a procedure that permits the use of steady-state information to constrain the identification of nonlinear polynomial models. Such a procedure has three main steps. First, a general framework is provided that relates the static function of nonlinear global polynomial models to their terms and parameters. Second, using standard nonlinear programming techniques, a rational function is fitted to the system static function, which is assumed to be known and is used as auxiliary information. Finally, the information gathered in the first two steps is used to write a set of equality constraints that are exactly satisfied by a standard constrained least-squares algorithm used to estimate the parameters of the identified model. It is shown that the resulting model will always have the specified static nonlinearity and will use additional degrees of freedom to fit the dynamics underlying the observed data.
IEEE Transactions on Magnetics, 1993
A time domain finite element method (TDFE) applied to the analysis of electrical transients on lo... more A time domain finite element method (TDFE) applied to the analysis of electrical transients on lossy transmission lines is presented. In this method, the general telegraph equations are solved numerically at discrete time steps. Examples of voltage waveforms on lossy single-phase lines are shown.
A meshless method for electromagnetic field computation is developed based on the multiquadric in... more A meshless method for electromagnetic field computation is developed based on the multiquadric interpolation technique. A global approximation to the solution is built based only on the discretization of the domain in nodes and the differential equations describing the problem in the domain and its boundary. An attractive characteristic of the multiquadric solution is that it is continuous and it has infinitely continuous derivatives. This is particularly important to obtain field quantities in electromagnetic analysis. The method is also capable of dealing with physical discontinuities present at the interface between different materials. The formulation is presented in the Cartesian and polar coordinates, which can be extended to other systems. We applied the formulation in the analysis of an electrostatic micromotor and a microstrip. The results demonstrate good agreement with other numerical technique, showing the adequacy of the proposed methodology for electromagnetic analysis.
... Antônio Carlos, 6627, Belo Horizonte, MG, Brasil mauricio.souza@pq.cnpq.br 4 Departamento de ... more ... Antônio Carlos, 6627, Belo Horizonte, MG, Brasil mauricio.souza@pq.cnpq.br 4 Departamento de Engenharia Elétrica, Universidade Federal de Minas Gerais, Av. ... The authors are grateful to Thiago Ferreira de Noronha, the coauthor of [7,8], for pro-viding datasets used. ...
This chapter is devoted to optimization formulations of satellite coverage problems and their sol... more This chapter is devoted to optimization formulations of satellite coverage problems and their solution. They are specially useful in satellite broadcasting applications, where the information goes from one to many. Due to distance from target and power supply constraints, highly directive efficient reflector antennas are the best choice. There are many possible optimization formulations for this problem, depending fundamentally on specifications and degrees of freedom in the system. Some specific coverage problems considering broadband, radiation pattern constraints and interference are presented, where the degrees of freedom are purely geometric.
This chapter is devoted to optimization formulations of satellite coverage problems and their sol... more This chapter is devoted to optimization formulations of satellite coverage problems and their solution. They are specially useful in satellite broadcasting applications, where the information goes from one to many. Due to distance from target and power supply constraints, highly directive efficient reflector antennas are the best choice. There are many possible optimization formulations for this problem, depending fundamentally on specifications and degrees of freedom in the system. Some specific coverage problems considering broadband, radiation pattern constraints and interference are presented, where the degrees of freedom are purely geometric.
Magnetics, IEEE …, Jan 1, 2004
Resumo -Este artigo apresenta uma configuração modificada de Algoritmos Genéticos com codificação... more Resumo -Este artigo apresenta uma configuração modificada de Algoritmos Genéticos com codificação real e utilizando cruzamento polarizado e mutação pelo comportamento da população, ambos por variável. Ela será aplicada na modelagem da forma do refletor com abertura circular de uma Antena Refletora Offset na busca do melhor diagrama de radiação para a área de cobertura do território brasileiro. A análise da antena é feita com a aproximação de ótica física corrigida por correntes equivalentes de borda. É realizada também uma breve discussão sobre codificação binária e real em Algoritmos Genéticos.
Page 1. Heuristique VND-ILS pour le Problème de Routage et d'Affectation de Longueur... more Page 1. Heuristique VND-ILS pour le Problème de Routage et d'Affectation de Longueur d'Onde Alexandre Xavier Martins1, Christophe Duhamel2, Philippe Mahey2, Maurício Cardoso de Souza3, Rodney Rezende Saldanha4 ...
Resumo: O uso de conhecimento a priori em identificação de sistemas como ferramenta auxiliar para... more Resumo: O uso de conhecimento a priori em identificação de sistemas como ferramenta auxiliar para a melhoria da estrutura e para a estimação de parâmetros vem se destacando nosúltimos anos. Com esse propósito, o presente trabalho parte das definições gerais em identificação caixa-preta (sem uso de conhecimento a priori ) e das características gerais da estrutura dos modelos NARX polinomiais para definir uma metodologia que permita usar conhecimento a priori nas etapas de escolha de estrutura e estimação de parâmetros utilizando ferramentas de otimização. Em geral, os modelos identificados fazendo-se uso de informação a priori têm um comportamento global melhor de que seus análogos obtidos por técnicas caixa-preta. Para ilustrar este fato será mostrado um exemplo utilizando-se dados medidos reais de um conversor CC-CC Buck.
... Antônio Carlos, 6627, Belo Horizonte, MG, Brasil mauricio.souza@pq.cnpq.br 4 Departamento de ... more ... Antônio Carlos, 6627, Belo Horizonte, MG, Brasil mauricio.souza@pq.cnpq.br 4 Departamento de Engenharia Elétrica, Universidade Federal de Minas Gerais, Av. ... The authors are grateful to Thiago Ferreira de Noronha, the coauthor of [7,8], for pro-viding datasets used. ...