arXiv subjects

Fabio Botelho

Publications and source records attributed to Fabio Botelho.

At least 19 recordsLinked to original sources

arXiv2020

A primal dual variational formulation and a multi-duality principle for a non-linear model of plates

This article develops a new primal dual formulation for the Kirchhoff-Love non-linear plate model. At first we establish a duality principle which includes sufficient conditions of global optimality through the dual formulation. At this point we highlight this first duality principle is specially suitable for the case in which the membrane stress tensor is negative definite. In a second step, from such a general principle, we develop a primal dual variational formulation which also includes the corresponding sufficient conditions for global optimality. The results are based on standard tools of convex analysis and on a well known Toland result for D.C. optimization. Finally, in the last section, we present a multi-duality principle and qualitative relations between the critical points of the primal and dual formulations. We formally prove there is no duality gap between such primal and dual formulations in a local extremal context.

math.OC↗

arXiv2020

A general variational formulation for relativistic mechanics based on fundamentals of differential geometry

The first part of this article develops a variational formulation for relativistic mechanics. The results are established through standard tools of variational analysis and differential geometry. The novelty here is that the main motion manifold has a $n+1$ dimensional range. It is worth emphasizing in a first approximation we have neglected the self-interaction energy part. In its second part, this article develops some formalism concerning the causal structure in a general space-time manifold. Finally, the last article section presents a result concerning the existence of a generalized solution for the world sheet manifold variational formulation.

math.GM↗

arXiv2019

A duality principle and related computational method for a class of structural optimization problems in elasticity

In this article we develop a duality principle and concerning computational method for a structural optimization problem in elasticity. We consider the problem of finding the optimal topology for an elastic solid which minimizes its structural inner energy resulting from the action of external loads to be specified. The main results are obtained through standard tools of convex analysis and duality theory. We emphasize our algorithm do not include a filter to process the results, so that the result obtained is indeed a critical point for the original optimization problem. Finally, we present some numerical examples concerning applications of the theoretical results established.

math.OC↗

arXiv2019

A variational formulation for relativistic mechanics, a new interpretation for the Bohr atomic model and some concerning applications

This article develops a variational formulation for the relativistic Klein-Gordon equation. The main results are obtained through an extension of the classical mechanics approach to a more general context, which in some sense, includes the quantum mechanics one. For the second part of the text, the definition of normal field and its relation with the wave function concept play a fundamental role in the main results establishment. Among the applications, we include a model with the presence of electromagnetic fields and also the modeling of a chemical reaction. Finally, in the last section, we present some results about the Spin operator in a relativistic context.

quant-ph↗

arXiv2019

On duality principles for one and three-dimensional non-linear models in elasticity

In this article, we develop duality principles applicable to primal variational formulations found in the non-linear elasticity theory. As a first application, we establish the concerning results in details for one and three-dimensional models. We emphasize such duality principles are applicable to a larger class of variational optimization problems, such as non-linear models of plates and shells and other models in elasticity. Finally, we formally prove there is no duality gap between the primal and dual formulations, in a local extremal context.

math.OC↗

arXiv2019

A primal dual variational formulation suitable for a large class of non-convex problems in optimization

In this article we develop a new primal dual variational formulation suitable for a large class of non-convex problems in the calculus of variations. The results are obtained through basic tools of convex analysis, duality theory, the Legendre transform concept and the respective relations between the primal and dual variables. The novelty here is that the dual formulation is established also for the primal variables, however with a large domain region of concavity about a critical point. Finally, we formally prove there is no duality gap between the primal and dual formulations in a local extremal context.

math.OC↗

arXiv2019

On the generalized method lines applied to the time-independent incompressible Navier-Stokes system

In the first part of this article, we obtain a linear system whose the solution solves the time-independent incompressible Navier-Stokes system for the special case in which the external forces vector is a gradient. In a second step we develop approximate solutions, also for the time independent incompressible Navier-Stokes system, through the generalized method of lines. We recall that for such a method, the domain of the partial differential equation in question is discretized in lines and the concerning solution is written on these lines as functions of the boundary conditions and boundary shape. Finally, we emphasize these last main results are established through applications of the Banach fixed point theorem.

math.GM↗

arXiv2019

Duality suitable for a class of non-convex optimization problems

In this article we develop a duality principle suitable for a large class of problems in optimization. The main result is obtained through basic tools of convex analysis and duality theory. We establish a correct relation between the critical points of the primal and dual formulations and formally prove there is no duality gap between such formulations, in a local extremal context.

math.OC↗

arXiv2019

A variational formulation for relativistic mechanics based on Riemannian geometry and its application to the quantum mechanics context

This article develops a variational formulation of relativistic nature applicable to the quantum mechanics context. The main results are obtained through basic concepts on Riemannian geometry. Standards definitions such as vector fields and connection have a fundamental role in the main action establishment. In the last section, as a result of an approximation for the main formulation, we obtain the relativistic Klein-Gordon equation.

math.AP↗

arXiv2019

On the generalized method of lines and its proximal explicit and hyper-finite difference approaches

This article firstly develops a proximal explicit approach for the generalized method of lines. In such a method, the domain of the PDE in question is discretized in lines and the equation solution is written on these lines as functions of the boundary conditions and domain shape. The main objective of introducing a proximal formulation is to minimize the solution error as a typical parameter $\varepsilon>0$ is too small. In a second step we present another procedure to minimize this same error, namely, the hyper-finite differences approach. In this last method the domain is divided in sub-domains on which the solution is obtained through the generalized method of lines allowing the parameter $\varepsilon>0$ to be very small without increasing the solution error. The solutions for the sub-domains are connected through the boundary conditions and the solution of the partial differential equation in question on the node lines which separate the sub-domains. In the last sections of each text part we present the concerning softwares and perform numerical examples.

math.NA↗

arXiv2019

A duality principle for non-convex optimization in $\mathbb{R}^n$

This article develops a duality principle for a class of optimization problems in $\mathbb{R}^n$. The results are obtained based on standard tools of convex analysis and on a well known result of Toland for D.C. optimization. Global sufficient optimality conditions are also presented as well as relations between the critical points of the primal and dual formulations. Finally we formally prove there is no duality gap between the primal and dual formulations in a local extremal context.

math.OC↗

arXiv2019

A note on optimization in $\mathbb{R}^n$

In this article, we develop an algorithm suitable for constrained optimization in $\mathbb{R}^n$. The results are developed through standard tools of n-dimensional real analysis and basic concepts of optimization. Indeed, the well known Banach fixed point theorem has a fundamental role in the main result establishment.

math.OC↗

arXiv2019

Existence of solution for an optimal control problem associated to the Ginzburg-Landau system in superconductivity

This article develops a global existence result for the solution of an optimal control problem associated to the Ginzburg-Landau system. This main result is based on standard tools of analysis and functional analysis, such as the Friedrichs Curl Inequality and the Rellich-Kondrashov Theorem. In the concerning model, we consider the presence of an external magnetic field and the control variable is a complex function acting on the super-conducting sample boundary. Finally the state variables are the Ginzburg-Landau order parameter and the magnetic potential, defined on domains properly specified.

math.OC↗

arXiv2018

A duality principle for non-linear elasticity

This article develops a duality principle for non-linear elasticity. The results are obtained through standard tools of convex analysis and the Legendre transform concept. We emphasize the dual variational formulation is concave. Moreover, sufficient optimality conditions are also established.

math.OC↗

arXiv2018

Global existence results and duality for non-linear models of plates and shells

In this article firstly we develop a new proof for global existence of minimizers for the Kirchhoff-Love plate model. We also present a duality principle and relating sufficient optimality conditions for such a variational plate model. In a second step, we present a global existence result for a non-linear model of shells. For this model, we also develop a duality principle and concerning sufficient conditions of optimality.

math.AP↗

arXiv2018

On General Duality Principles for Non-Convex Variational Optimization with Applications to the Ginzburg-Landau System in Superconductivity

This article develops duality principles applicable to non-convex models in the calculus of variations. The results here developed are applied to Ginzburg-Landau type equations. For the first and second duality principles, through an optimality criterion developed for the dual formulations, we qualitatively classify the critical points of the primal and dual functionals in question. We formally prove there is no duality gap between the primal and dual formulations in a local extremal context. Finally, in the last sections, we present a global existence result, a duality principle and respective optimality conditions for the complex Ginzburg-Landau system in superconductivity in the presence of a magnetic field and concerning magnetic potential.

math.OC↗

arXiv2018

On central fields in the calculus of variations

This article develops sufficient conditions of local optimality for the scalar and vectorial cases of the calculus of variations. The results are established through the construction of stationary fields which keep invariant what we define as the generalized Hilbert integral.

math.OC↗

arXiv2018

On duality principles for non-convex variational models applied to a Ginzburg-Landau type equation

This article develops a duality principle applicable to a large class of variational problems. Firstly, we apply the results to a Ginzburg-Landau type model. In a second step, we develop another duality principle and related primal dual variational formulation and such an approach includes optimality conditions which guarantee zero duality gap between the primal and dual formulations. We emphasize in both cases the dual variational formulations obtained have large regions of concavity about the critical points in question.

math.OC↗