This paper deals with multiobjective optimization programs in which the objective functions are ordered by their degree of priority. A number of approaches have been proposed (and several implemented) for the solution...
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This paper deals with multiobjective optimization programs in which the objective functions are ordered by their degree of priority. A number of approaches have been proposed (and several implemented) for the solution of lexicographic (preemptive priority) multiobjective optimization programs. These approaches may be divided into two classes. The first encompasses the development of algorithms specifically designed to deal directly with the initial model. Considered only for linear multiobjective programs and multiobjective programs with a finite discrete feasible region, the second one attempts to transform, efficiently, the lexicographic multiobjective model into an equvivalent model, i.e. a single objective programming problem. In this paper, we deal with the second approach for lexicographic nonlinear multiobjective programs.
The transfer capability on a transmission path is limited by constraints on acceptability, voltage security, small-signal stability, and transient stability. For a large interconnected power grid, these constraints ar...
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The transfer capability on a transmission path is limited by constraints on acceptability, voltage security, small-signal stability, and transient stability. For a large interconnected power grid, these constraints are influenced significantly by the interactions among path flows in different control areas. When a critical transmission path capability is limited by one of these constraints, it may be necessary to coordinate the interarea power transfers so as to improve the transfer capability on the constrained path without compromising on the security criteria. Based on such considerations, this paper presents a novel multiobjective methodology in which global strategies are developed for the improvement and coordination of transmission path transfers. The problem is formulated with respect to various constraints into suitable optimization problems. An efficient nonlinear programming algorithm with sufficient line search step is incorporated for finding optimal solutions while also incorporating security and stability constraints. The MW benefits for the transfer capability from the coordination procedure are explicitly demonstrated after the optimization process. The effectiveness of the methodology is illustrated by case studies on improving the capability of the California-Oregon Intertie (COI) for large-scale WECC western American power system models.
In this paper we analyse the scalability of seven multiobjective evolutionary algorithms when they solve large instances of a known biological problem, the motif discovery problem (MDP). The selected algorithms are a ...
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In this paper we analyse the scalability of seven multiobjective evolutionary algorithms when they solve large instances of a known biological problem, the motif discovery problem (MDP). The selected algorithms are a population-based and a trajectory-based algorithms (DEPT and MO-VNS, respectively), three swarm intelligence algorithms (MOABC, MO-FA, and MO-GSA), a genetic algorithm (NSGA-II), and SPEA2. The MDP is one of the most important sequence analysis problems related to discover common patterns, motifs, in DNA sequences. A motif is a nucleic acid sequence pattern that has some biological significance as being DNA binding sites for a regulatory protein, i.e., a transcription factor (TF). A biologically relevant motif must have a certain length, be found in many sequences, and present a high similarity among the subsequences which compose it. These three goals are in conflict with each other, therefore a multiobjective approach is a good way of facing the MDP. In addition, in recent years, scientists are decoding genomes of many organisms, increasing the computational workload of the algorithms. Therefore, we need algorithms that are able to deal with these new large DNA instances. The obtained experimental results suggest that MOABC and MO-FA are the algorithms with the best scalability behaviours.
With the number of alternative systems increasing, the system portfolio selection problem for large-scale complex systems is an non-deterministic polynomial (NP)-hard problem. The time cost of the classification selec...
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With the number of alternative systems increasing, the system portfolio selection problem for large-scale complex systems is an non-deterministic polynomial (NP)-hard problem. The time cost of the classification selection algorithm used for the portfolio selection is intolerable;thus, improving the algorithm is necessary. In this paper, first, the weapon system portfolio selection (WSPS) model is categorized into two types: single objective and multiobjective;the optimization difficulties are analyzed;and the feasible solution space reduction strategy is given. Second, a portfolio selection optimization algorithm based on the difference evolution technique for order preference by similarity to ideal solution (DE-TOPSIS) is proposed where the weapon system weighting method TOPSIS is integrated with the DE algorithm. Finally, considering different weapon system scales, the advantages of the proposed algorithm are illustrated by comparing it with two other algorithms in a single-target case and two other algorithms in a multiobjective case. The results indicate that the DE algorithm always has better performance with regard to optimal solution quality, convergence speed, and algorithm stability.
In this paper, the so-called eta-approximation approach is used to obtain the sufficient conditions for a nonlinear multiobjective programming problem with univex functions with respect to the same function eta. In th...
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In this paper, the so-called eta-approximation approach is used to obtain the sufficient conditions for a nonlinear multiobjective programming problem with univex functions with respect to the same function eta. In this method, an equivalent eta-approximated vector optimization problem is constructed by a modification of both the objective and the constraint functions in the original multiobjective programming problem at the given feasible point. Moreover, to find the optimal solutions of the original multiobjective problem, it sufficies to solve its associated eta-approximated vector optimization problem. Finally, the description of the eta-approximation algorithm for solving a nonlinear multiobjective programming problem involving univex functions is presented.
A pair of Wolfe type multiobjective second order symmetric dual programs with cone constraints is formulated and usual duality results are established under second order invexity assumptions. These results are then us...
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A pair of Wolfe type multiobjective second order symmetric dual programs with cone constraints is formulated and usual duality results are established under second order invexity assumptions. These results are then used to investigate symmetric duality for minimax version of multiobjective second order symmetric dual programs wherein some of the primal and dual variables are constrained to belong to some arbitrary sets, i.e., the sets of integers. This paper points out certain omissions and inconsistencies in the earlier work of Mishra [S.K. Mishra, multiobjective second order symmetric duality with cone constraints, European journal of Operational Research 126 (2000) 675-682] and Mishra and Wang [S.K. Mishra, S.Y. Wang, Second order symmetric duality for nonlinear multiobjective mixed integer programming, European journal of Operational Research 161 (2005) 673-682]. (C) 2009 Elsevier B.V. All rights reserved.
This study is devoted to constraint qualifications and strong Kuhn-Tucker necessary optimality conditions for nonsmooth multiobjective optimization problems. The main tool of the study is the concept of convexificator...
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This study is devoted to constraint qualifications and strong Kuhn-Tucker necessary optimality conditions for nonsmooth multiobjective optimization problems. The main tool of the study is the concept of convexificators. Mangasarian-Fromovitz type constraint qualification and several other qualifications are proposed and their relationships are investigated. In addition, sufficient optimality conditions are studied. (C) 2011 Elsevier Ltd. All rights reserved.
We propose and analyse a nonmonotone quasi-Newton algorithm for unconstrained strongly convex multiobjective optimization. In our method, we allow for the decrease of a convex combination of recent function values. We...
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We propose and analyse a nonmonotone quasi-Newton algorithm for unconstrained strongly convex multiobjective optimization. In our method, we allow for the decrease of a convex combination of recent function values. We establish the global convergence and local superlinear rate of convergence under reasonable assumptions. We implement our scheme in the context of BFGS quasi-Newton method for solving unconstrained multiobjective optimization problems. Our numerical results show that the nonmonotone quasi-Newton algorithm uses fewer function evaluations than the monotone quasi-Newton algorithm.
This article presents a methodological approach for the formulation of control strategies capable of reducing atmospheric pollution at the standards set by European legislation. The approach was implemented in the gre...
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This article presents a methodological approach for the formulation of control strategies capable of reducing atmospheric pollution at the standards set by European legislation. The approach was implemented in the greater area of Thessaloniki and was part of a project aiming at the compliance with air quality standards in five major cities in Greece. The methodological approach comprises two stages: in the first stage, the availability of several measures contributing to a certain extent to reducing atmospheric pollution indicates a combinatorial problem and favors the use of Integer programming. More specifically, Multiple Objective Integer programming is used in order to generate alternative efficient combinations of the available policy measures on the basis of two conflicting objectives: public expenditure minimization and social acceptance maximization. In the second stage, these combinations of control measures (i.e., the control strategies) are then comparatively evaluated with respect to a wider set of criteria, using tools from Multiple Criteria Decision Analysis, namely, the well-known PROMETHEE method. The whole procedure is based on the active involvement of local and central authorities in order to incorporate their concerns and preferences, as well as to secure the adoption and implementation of the resulting solution.
The allocation of water in a multicountry river system necessarily involves conflicting objectives, where increasing water benefits for one country entails losses for other countries. This paper presents the formulati...
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The allocation of water in a multicountry river system necessarily involves conflicting objectives, where increasing water benefits for one country entails losses for other countries. This paper presents the formulation and application of a multiobjective linear programming model, where each objective represents the benefits for a country from using water for agriculture, urban consumption. and energy production, net of conveyance costs. This model is applied to the Euphrates and Tigris River basin and its three riparian countries-Turkey, Syria, and Iraq. The model is used to delineate the set of nondominated Solutions (Pareto frontier), and is extended to include political factors and distributional constraints, leading to ail allocation of basin water and resulting benefits.
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