A convex analysis approach for convex multiplicative programming

Global optimization problems involving the minimization of a product of convex functions on a convex set are addressed in this paper. Elements of convex analysis are used to obtain a suitable representation of the convex multiplicative problem in the outcome space, where its global solution is reduced to the solution of a sequence of quasiconcave minimizations on polytopes. Computational experiments illustrate the performance of the global optimization algorithm proposed.41457959

A game-theoretic approach for the web services scheduling problem

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)We address the design of an Internet-based business process composed of several web services by using multiobjective optimization and game-theoretic methods. Adopting a suitable representation for the business process, we present a mathematical optimization problem which considers several quality-of-service objectives: cost, execution time, reliability, availability and reputation. The web service scheduling problem is formulated as a multiobjective mixed-integer linear optimization problem and solved through a goal optimization method. The optimal solution of the scheduling problem assigns suppliers to all the tasks that comprise the business process, thus establishing the revenues - utilities - of all the suppliers. We then model the interaction between the suppliers as an incomplete information (Bayesian) game: the structure of the game is common knowledge of all the suppliers, but each supplier knows only his/her own utility function. A characterization of the Bayes-Nash equilibria of the game is provided. The paper includes numerical examples. (C) 2014 Elsevier Ltd. All rights reserved.411047434751Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq [307926/2009-5

Bi-objective optimisation with multiple decision-makers: a convex approach to attain majority solutions

An interactive approach for solving bi-objective optimisation problems with multiple decision-makers in a context where the decisions are made via the strict majority voting rule is proposed. An adequate use of projection and decomposition techniques leads to a hierarchical algorithm in which the upper level is represented by a relaxed version of the bi-objective problem in the objective space. The feasibility of the partial consensus obtained in the upper (decision) level by the strict majority voting rule is tested in the lower (analysis) level of the algorithm. Some properties of the relaxed bi-objective problem allow that different preference structures of the decision-makers can be represented by appropriate multiobjective methods. The paper includes numerical examples that illustrate the characteristics of the approach proposed.51333334

On the Solution of Generalized Multiplicative Extremum Problems

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The paper addresses the problem of maximizing a sum of products of positive and concave real-valued functions over a convex feasible set. A reformulation based on the image of the feasible set through the vector-valued function which describes the problem, combined with an adequate application of convex analysis results, lead to an equivalent indefinite quadratic extremum problem with infinitely many linear constraints. Special properties of this later problem allow to solve it by an efficient relaxation algorithm. Some numerical tests illustrate the approach proposed.1492411419Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

AN INTERACTIVE PROJECTION METHOD FOR MULTICRITERIA OPTIMIZATION PROBLEMS

20359660

Solving multiple-objective problems in the objective space

Projection and relaxation techniques are employed to decompose a multiobjective problem into a two-level structure. The basic manipulation consists in projecting the decision variables onto the space of the implicit tradeoffs, allowing the definition of a relaxed multiobjective master problem directly in the objective space. An additional sub-problem tests the feasibility of the solution encountered by the relaxed problem. Some properties of the relaxed problem (linearity, small number of variables, etc.) render its solution efficient by a number of methods. Representatives of two different classes of multiobjective methods [the Geoffrion, Dyer, Feinberg (GDF) method and the fuzzy method of Baptistella and Ollero] are implemented and applied within this context to a water resources allocation problem. The results attest the computational viability of the overall procedure and its usefulness for the solution of multiobjective problems.89365968

Lateral/directional control for an autonomous, unmanned airship

Project AURORA aims at the development of an unmanned airship capable of autonomous flight over user-defined locations for aerial inspection and imagery, acquisition. Presents a guidance control strategy for the trajectory path following of the AURORA airship, where the objective is to make the vehicle follow a set of predefined points. The guidance strategy is based on a path tracking error generation methodology that takes into account both the distance and the angular errors of the airship with respect to the desired trajectory. The guidance system is composed of a path tracking guidance controller (as outer loop) and a heading controller (as inner loop), using the rudder deflection. Also proposes an additional roll controller, using the aileron input, in order to reduce rolling oscillations during yaw maneuvering and due to atmospheric turbulence.73545345

Ocorrência de dermatófitos em amostras de unhas, pés e mãos coletadas de estudantes universitários Occurrence of dermatophyte, in nails, feet and hands of universitary students

Este trabalho teve como objetivo, avaliar a presença de dermatófitos, especificamente em unhas, pés e mãos de estudantes universitários com e sem lesões sugestivas de dermatofitose. Foram coletadas 280 amostras dessas regiões, das quais 31 (11,1%) apresentaram positividade apenas pelo exame direto, e 20 (7,1%) tiveram, além do exame direto positivo, crescimento de dermatófito, mediante cultivo da amostra biológica. T. rubrum foi o dermatófito isolado com maior freqüência (80%), seguido por T. mentagrophytes (20%). Considerando os sítios analisados neste trabalho, a ocorrência de dermatófitos foi observada em 10,4% nas unhas dos pés, 5% nas escamas de pés, 2,5% nas unhas das mãos e apenas 0,4% nas escamas das mãos.<br>The objective of this paper was to evaluate the occurrence of dermatophytes, specifically in the nails, feet and hands of university students with and without lesions. Two hundred and eighty samples were collected; 31 (11.1%) were positive by direct examination, while only 20 (7.1%) showed dermatophyte growth in culture, as well as direct positive examination. Trichophyton rubrum was the most frequently isolated (80%) dermatophyte followed by T. mentagrophytes (20%). Considering the sites analyzed, dermatophyte occurrence was: 10.4% in toenails, 5% in foot skin, 2.5% in fingernails and 0.4% in hand skin