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- A. Ismael F. Vaz, Luís N. Vicente
- J. Global Optimization
- 2007

In this paper we develop, analyze, and test a new algorithm for the global minimization of a function subject to simple bounds without the use of derivatives. The underlying algorithm is a pattern search method, more specifically a coordinate search method, which guarantees convergence to stationary points from arbitrary starting points. In the optional… (More)

- A. L. Custódio, J. F. A. Madeira, A. Ismael F. Vaz, Luís N. Vicente
- SIAM Journal on Optimization
- 2011

In practical applications of optimization it is common to have several conflicting objective functions to optimize. Frequently, these functions are subject to noise or can be of black-box type, preventing the use of derivative-based techniques. We propose a novel multiobjective derivative-free methodology, calling it direct multisearch (DMS), which does not… (More)

- A. Ismael F. Vaz, Edite M. G. P. Fernandes, M. Paula S. F. Gomes
- ACM Trans. Math. Softw.
- 2004

SIPAMPL is an environment for coding semi-infinite programming (SIP) problems. This environment includes a database containing a set of SIP problems that have been collected from the literature and a set of routines. It allows users to code their own SIP problems in AMPL, to use any problem already in the database, and to develop and test any SIP solver.… (More)

- A. Ismael F. Vaz, Luís N. Vicente
- Optimization Methods and Software
- 2009

PSwarm was developed originally for the global optimization of functions without derivatives and where the variables are within upper and lower bounds. The underlying algorithm used is a pattern search method, more specifically a coordinate search method, which guarantees convergence to stationary points from arbitrary starting points. In the (optional)… (More)

- A. Ismael F. Vaz, Edite M. G. P. Fernandes, M. Paula S. F. Gomes
- European Journal of Operational Research
- 2004

— In this paper we describe how robot trajectory planning can be formulated as a semi-infinite programming (SIP) problem. The formulation as a SIP problem allowed us to treat the problem with one of the three main classes of methods for solving SIP, the discretization class. Two of the robotics trajectory planning problems formulated were coded in the… (More)

Keywords: Air pollution control Gaussian dispersion model Semi-infinite programming SIPAMPL database NSIPS solver a b s t r a c t Environment issues are more than ever important in a modern society. Complying with stricter legal thresholds on pollution emissions raises an important economic issue. This paper presents some ideas in the use of optimization… (More)

In this paper we address the global optimization of functions subject to bound and linear constraints without using derivatives of the objective function. We investigate the use of derivative-free models based on radial basis functions (RBFs) in the search step of direct-search methods of directional type. We also study the application of algorithms based… (More)

Context. Modeling a single star with theoretical stellar evolutionary tracks is a nontrivial problem because of a large number of unknowns compared to the number of observations. A current way of estimating stellar age and mass consists of using interpolations in grids of stellar models and/or isochrones, assuming ad hoc values for the mixing length… (More)

- A. ISMAEL F. VAZ
- 2006

In this paper we develop, analyze, and test a new algorithm for the global minimization of a function subject to simple bounds without the use of derivatives. The underlying algorithm is a pattern search method, more specifically a coordinate search method, which guarantees convergence to stationary points from arbitrary starting points. In the optional… (More)

Optimal control problems appear in several engineering fields and in particular on the control of fed-batch fermentation processes. These problems are often described by sets of nonlinear differential and algebraic equations, usually subject to constraints in the state and control variables. Tradicional approaches to the optimal feed trajectory computation… (More)