Often decision makers have to cope with a programming problem with unknown quantitities. Then they will estimate these quantities and solve the problem as it then appears-the 'approximate problem'. Thus there ...
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Often decision makers have to cope with a programming problem with unknown quantitities. Then they will estimate these quantities and solve the problem as it then appears-the 'approximate problem'. Thus there is a need to establish conditions which will ensure that the solutions to the approximate problem will come close to the solutions to the true problem in a suitable manner. Confidence sets, i.e. sets that cover the true sets with a given prescribed probability, provide useful quantitative information. In this paper we consider multiobjective problems and derive confidence sets for the sets of efficient points, weakly efficient points, and the corresponding solution sets. Besides the crucial convergence conditions for the objective and/or constraint functions, one approach for the derivation of confidence sets requires some knowledge about the true problem, which may be not available. Therefore also another method, called relaxation, is suggested. This approach works without any knowledge about the true problem. The results are applied to the Markowitz model of portfolio optimization.
In this paper, the problem of the determination of Pareto optimal solutions for certain large-scale systems with multiple conflicting objectives is considered. As a consequence, a two-level hierarchical method is prop...
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In this paper, the problem of the determination of Pareto optimal solutions for certain large-scale systems with multiple conflicting objectives is considered. As a consequence, a two-level hierarchical method is proposed, where the global problem is decomposed into smaller multiobjective problems (lower level) which are coordinated by an upper level that has to take into account the relative importance assigned to each subsystem. The scheme that has been developed is an iterative one, so that a continuous information exchange is carried out between both levels in order to obtain efficient solutions for the initial global problem. The practical implementation of the developed scheme allows us to prove its efficiency in terms of processing time.
In this paper, we propose a new credibility function for a fuzzy variable that can accommodate the attitude of the investor (pessimistic, optimistic, or neutral) along with capturing the return expectations. We use an...
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In this paper, we propose a new credibility function for a fuzzy variable that can accommodate the attitude of the investor (pessimistic, optimistic, or neutral) along with capturing the return expectations. We use an adaptive index, which the investors can use to specify their general perception of the financial market. We extend the classic mean-variance model so that it provides greater flexibility to the investors in specifying their requirements viz., level of diversification, minimum and maximum level of investment in a particular asset, and the skewness requirement. We also replace variance with mean-absolute semideviation as a measure of quantifying risk, which is more realistic, and solve the resultant multiobjective credibility model with a real-coded genetic algorithm. Numerical examples have been provided at the end to illustrate the methodology and advantages of the model.
In a recent paper on multiobjective maximization problems (Ref. 1), the authors use explicit quasiconcavity of the objective functions to prove a characterization of weakly efficient solutions and local-global propert...
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In a recent paper on multiobjective maximization problems (Ref. 1), the authors use explicit quasiconcavity of the objective functions to prove a characterization of weakly efficient solutions and local-global properties. We provide results which are stronger in part and are derived with shorter proofs. We also present additional results.
Numerous techniques for generating approximate solutions have been proposed in the last decade for routing and scheduling in multi vehicle dial-a-ride problems. While some of these techniques have mathematical foundat...
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Numerous techniques for generating approximate solutions have been proposed in the last decade for routing and scheduling in multi vehicle dial-a-ride problems. While some of these techniques have mathematical foundations, it is often difficult to assess the global optimality of the generated solution due to the use of pure local improvement methods. In additon, most of these methods are based on a single objective, such as minimization of the number of vehicles used, and cannot account for different or competing objectives that characterize the problem. This paper proves the intractability of the dial-a-ride problem, and then describes a new approximate method based on simulated annealing that is used to solve these problems in the presence of multiple objectives.
We formulate and study a multiobjective programming approach for production processes which implements suitable constraints on pollutant emissions. We consider two alternative optimization problems: (a) minimum pollut...
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We formulate and study a multiobjective programming approach for production processes which implements suitable constraints on pollutant emissions. We consider two alternative optimization problems: (a) minimum pollution risk;(b) maximum expected return. For each pollutant, we define three different contamination levels: (a) the desirable or the target pollution level, (b) the alarm (warning or critical) level and (c) the maximum admissible (acceptable) level, and introduce penalties proportional to the amounts of pollutants that exceed these levels. The objective function of the minimum pollution risk problem is not smooth since it contains positive parts of some affine functions, resulting in mathematical difficulties, which can be solved by formulating an alternative linear programming model, which makes use of additional variables and has the same solutions as the initial problem. We investigate various particular cases and analyze a numerical example for a textile plant. (C) 2007 Elsevier B.V. All rights reserved.
To tackle the challenge of onsite resource reuse of composite muck, which relies on a shield tunneling section in the case of Nanjing Metro Line 7, this paper examines the effects of component substitution and varying...
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To tackle the challenge of onsite resource reuse of composite muck, which relies on a shield tunneling section in the case of Nanjing Metro Line 7, this paper examines the effects of component substitution and varying proportions of factors on slurry properties through laboratory tests and multiobjective modeling. From a practical application perspective, the potential of using composite muck as a synchronous grouting material for shield tunneling was explored. In reference to the common mixed strata encountered in shield tunneling construction in the Nanjing area, a general slurry mixing ratio suitable for various mixed strata conditions was derived. The research results indicate the following optimized mixing ratios for the composite muck slurry: a water-to-binder (cement + fly ash) ratio of 0.76, a cement-to-fly ash ratio of 0.53, a binder-to-soil (silty clay + silty fine sand + river sand) ratio of 0.67, a clay (i.e., silty clay)-to-sand (i.e., silty fine sand + river sand) ratio of 0.4, and a substitution ratio (i.e., silty fine sand/silty fine sand + river sand) of 0.2. This slurry is feasible for practical applications and can reduce construction costs by 38.13%. The obtained general mixing ratio for the composite muck slurry, suitable for various mixed stratigraphic conditions, essentially meets onsite construction requirements (the bleeding rate is controlled within a low range of 1.1-3.1%, and the maximum compressive strength reaches up to 6.76 MPa at 28 days), with reasonable costs. It streamlines construction by eliminating the need for onsite screening of muck, allowing for the direct onsite reuse of composite muck in shield tunneling.
This paper addresses an important problem in the field of livestock ration formulation: the rigidity of the right-hand sides of the model. Thus, instead of considering the nutritional requirements as fixed values they...
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This paper addresses an important problem in the field of livestock ration formulation: the rigidity of the right-hand sides of the model. Thus, instead of considering the nutritional requirements as fixed values they are considered as targets which may or may not be achieved. In this way a multigoal programming model is formulated. The preferences of the ration-formulator are elicited resorting to the interactive method proposed by Zionts and Wallenius. The approach proposed is applied to a ration formulation problem for dairy cows in the Pedroches Valley in Andalusia, Spain.
In this paper, a pair of Mond-Weir type nondifferentiable multiobjective second-order symmetric dual programs over arbitrary cones is formulated. Weak, strong and converse duality theorems are established under second...
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In this paper, a pair of Mond-Weir type nondifferentiable multiobjective second-order symmetric dual programs over arbitrary cones is formulated. Weak, strong and converse duality theorems are established under second-order K-F-convexity/K-eta-bonvexity assumptions. A self duality theorem is also obtained by assuming the functions involved to be skew-symmetric.
In this paper we suggest an approach for solving a multiobjective stochastic linear programming problem with normal multivariate distributions. Our approach is a combination between a multiobjective method and a nonco...
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In this paper we suggest an approach for solving a multiobjective stochastic linear programming problem with normal multivariate distributions. Our approach is a combination between a multiobjective method and a nonconvex technique. The problem is first transformed into a deterministic multiobjective problem introducing the expected value criterion and an utility function that represents the decision makers preferences. The obtained problem is reduced to a mono-objective quadratic problem using a weighting method. This last problem is solved by DC (Difference of Convex) programming and DC algorithm. A numerical example is included for illustration.
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