Eduardo Souza de Cursi

An Approach for the Reliability Based Design Optimization of Laminated Composite Plates

This article aims at optimizing laminated composite plates taking into account uncertainties in the structural dimensions. As laminated composites require a global optimization tool, the Particle Swarm Optimization (PSO) method is employed. A new Reliability Based Design Optimization (RBDO) methodology based on safety factors is presented and coupled with PSO. Such safety factors are derived from the Karush–Kuhn–Tucker optimality conditions of the reliability index approach and eliminate the need for reliability analysis in RBDO. The plate weight minimization is the objective function of the optimization process. The results show that the coupling of the evolutionary algorithm with the safety-factor method proposed in this article successfully performs the RBDO of laminated composite structures.

Reliability-Based Optimization

Structural optimization looks for the best design of elements involved in a structure. Usually, the objective is cost or mass reduction and restrictions must be taken into account: for instance, a given available space imposes a restriction or failure criteria must be taken into account. Regarding practical applications, the objective and the restrictions may contain parameters affected by uncertainty: for instance, experimental data or material parameters having some variability. In addition, the external loads may appear as incertain: for instance, the design of a structure submitted to wind, sea waves or random vibration must take into account the intrinsic variability and uncertainty of the external loads.

Random perturbation of the projected variable metric method for nonsmooth nonconvex optimization problems with linear constraints

Random perturbation of the projected variable metric method for nonsmooth nonconvex optimization problems with linear constraints We present a random perturbation of the projected variable metric method for solving linearly constrained nonsmooth (i.e., nondifferentiable) nonconvex optimization problems, and we establish the convergence to a global minimum for a locally Lipschitz continuous objective function which may be nondifferentiable on a countable set of points. Numerical results show the effectiveness of the proposed approach.

DESIGN OPTIMIZATION OF A RANDOM SUSPENSION DEVICE CONSIDERING A RELIABILITY CONSTRAINT ON THE FREQUENCY RESPONSE FUNCTION

This work deals with the design of a suspension device, idealized as a spring-mass-damper system. The amplitude of a nominal system is constrained to satisfy certain limitations in a given frequency band and the design is to be done as a reliability-based optimization. This constitutes a major difficulty since the constraint becomes a random process. To concentrate in the main ideas, only the stiffness of the system will be considered random. The stiffness is characterized by a uniform random variable, and its mean and standard deviation are the optimization parameters. The design problem is stated as a two-objective optimization. They are the mean and the standard deviation of the stiffness: one search for the lowest stiffness and the greatest standard deviation, while the amplitude response must be within the acceptable domain of vibration, which is prescribed. To generate the Pareto front, the Normal Boundary Intersection method is used in the RFNM algorithm. Results show that a not-connected Pareto curve can be obtained for some choice of constraint. Hence, in this simple example, one shows that difficult situations can occur in the design of dynamic systems when prescribing an amplitude-response hull. Despite the simplicity of the example treated here, chosen to highlight the main ideas without distraction, the strategy proposed here can be generalized for more complex cases and give valuable results, able to help designers to choose for the best compromise between the mean and the standard deviation in reliability-based designs.

7 – Optimization Under Uncertainty

Optimization looks for the best values of some parameters with regard to a given cost, under given restrictions. If some of these elements involve parameters collected in a vector v, the solution x becomes a function x (y) of v. Thus, when stochastic or variable parameters are part of the optimization problem, the solutions become stochastic or variable too.

Nonlinear Algebraic Equations Involving Random Parameters

In this section, we consider systems of algebraic equations: F ( X v)=0, F X v = 0 ,

Stochastic perturbation of reduced gradient & GRG methods for nonconvex programming problems

In this paper, we consider nonconvex differentiable programming under linear and nonlinear differentiable constraints. A reduced gradient and GRG (generalized reduced gradient) descent methods involving stochastic perturbation are proposed and we give a mathematical result establishing the convergence to a global minimizer. Numerical examples are given in order to show that the method is effective to calculate. Namely, we consider classical tests such as the statistical problem, the octagon problem, the mixture problem and an application to the linear optimal control servomotor problem.

Evaluación de accesibilidad geográfica de los sistemas de salud jerárquicos, utilizando el modelo de p-mediana: aplicación en Santa Catarina, Brasil

Este trabalho tem por objetivo comparar a distribuicao de unidades hospitalares, considerando os diferentes graus de especializacao, em Santa Catarina, Brasil, com a distribuicao de unidades resultantes da aplicacao do modelo hierarquico de p-medianas, em tres niveis. O modelo de p-medianas e usado para determinar a localizacao das unidades, e a seguir e comparado o deslocamento medio da populacao para alcancar as unidades medicas nos dois cenarios, o atual e o simulado. Um indicador quantitativo de acessibilidade e proposto e e usado para avaliar a acessibilidade da distribuicao atual com a simulada. O trabalho tem o intuito de revelar regioes subatendidas, e de servir de ferramenta de auxilio a decisao de gestores na area de saude para possiveis intervencoes no sistema, no sentido de torna-la mais homogenea e mais acessivel a populacao

Avaliação de acessibilidade geográfica em sistemas de saúde hierarquizados usando o modelo de p-medianas: aplicação em Santa Catarina, Brasil

Este trabalho tem por objetivo comparar a distribuicao de unidades hospitalares, considerando os diferentes graus de especializacao, em Santa Catarina, Brasil, com a distribuicao de unidades resultantes da aplicacao do modelo hierarquico de p-medianas, em tres niveis. O modelo de p-medianas e usado para determinar a localizacao das unidades, e a seguir e comparado o deslocamento medio da populacao para alcancar as unidades medicas nos dois cenarios, o atual e o simulado. Um indicador quantitativo de acessibilidade e proposto e e usado para avaliar a acessibilidade da distribuicao atual com a simulada. O trabalho tem o intuito de revelar regioes subatendidas, e de servir de ferramenta de auxilio a decisao de gestores na area de saude para possiveis intervencoes no sistema, no sentido de torna-la mais homogenea e mais acessivel a populacao

[Assessment of geographic accessibility in hierarchical health systems using the p-median model: an application in Santa Catarina State, Brazil].

Este trabalho tem por objetivo comparar a distribuicao de unidades hospitalares, considerando os diferentes graus de especializacao, em Santa Catarina, Brasil, com a distribuicao de unidades resultantes da aplicacao do modelo hierarquico de p-medianas, em tres niveis. O modelo de p-medianas e usado para determinar a localizacao das unidades, e a seguir e comparado o deslocamento medio da populacao para alcancar as unidades medicas nos dois cenarios, o atual e o simulado. Um indicador quantitativo de acessibilidade e proposto e e usado para avaliar a acessibilidade da distribuicao atual com a simulada. O trabalho tem o intuito de revelar regioes subatendidas, e de servir de ferramenta de auxilio a decisao de gestores na area de saude para possiveis intervencoes no sistema, no sentido de torna-la mais homogenea e mais acessivel a populacao