Water is a very limited resource in Tunisia, both in quantity and in quality. Problems of quality are related to urban, industrial and agricultural activity. Erosion is causing dams to silt up and is leading to phosph...
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Water is a very limited resource in Tunisia, both in quantity and in quality. Problems of quality are related to urban, industrial and agricultural activity. Erosion is causing dams to silt up and is leading to phosphorus accumulation in water. The use of agrochemicals, primarily nitrogen and phosphorus, is causing problems of eutrophication. This paper presents the results of a study of sediment and nitrate pollution. The methodology used is based on the EPIC simulation model and a multi-objective programming model (MOPM). The data generated by EPIC are input for the MOPM together with the economic variables. These tools are applied to a 486 ha farm located in northern Tunisia which includes an irrigated area of 300 ha. The study considers three objectives: maximization of gross margin, minimization of erosion, and minimization of nitrate losses. The non-inferior set estimation method is implemented to generate the trade-off curves between the objectives. Results show that nitrate losses are important for both rainfed and irrigated land. The same conclusion is valid for erosion. It is shown that the farmer can reduce the environmental burden without decreasing gross margin, since he is operating below the efficiency curve.
This paper focuses on the design, development and implementation of new Pareto efficiency detection and restoration techniques for integer goal programming. The design of the algorithms and their implementation issues...
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This paper focuses on the design, development and implementation of new Pareto efficiency detection and restoration techniques for integer goal programming. The design of the algorithms and their implementation issues within (an otherwise continuous) goal programming system are detailed. The differences between continuous and integer goal programming regarding Pareto efficiency detection and restoration analysis are described. The integer Pareto efficiency techniques have been applied to a selection of problems from different industrial contexts in order to assess their computational performance. Finally, Pareto restoration and detection techniques are applied to an integer goal programming problem to illustrate the methodology. (C) 1999 Elsevier Science Ltd. All rights reserved.
Fractional programming is presented as a tool for studying the sustainability of agricultural systems. The essentials of the technique in both the single and the multi-objective cases are outlined. The lack of friendl...
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Fractional programming is presented as a tool for studying the sustainability of agricultural systems. The essentials of the technique in both the single and the multi-objective cases are outlined. The lack of friendly algorithms embedded in programming packages to solve the models is a shortcoming for the extensive use of a technique well adapted to represent many problems in economics. Two procedures for avoiding this shortcoming in the multiple objective case are discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.
The computational difficulty of obtaining the efficient set in multi-objective programming, specially in nonlinear problems, suggest the need of considering an approximation approach to this problem. In this paper, we...
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The computational difficulty of obtaining the efficient set in multi-objective programming, specially in nonlinear problems, suggest the need of considering an approximation approach to this problem. In this paper, we provide the computational results of the relationships between an approximation to the efficient set and the feasible and efficient sets. Random problem generation is considered for different sizes of the feasible set and we study the implications with respect to the number of objective functions and various kinds of objective functions. Computational experience with this approximation suggests that we obtain a substantial improvement when it increases the number of objective functions.
The paper presents a procedure for supporting the process of production planning in decentralized organizations. A situation is considered similar to that of the Dantzig/Wolfe algorithm: several divisions use scarce p...
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The paper presents a procedure for supporting the process of production planning in decentralized organizations. A situation is considered similar to that of the Dantzig/Wolfe algorithm: several divisions use scarce production resources that are controlled by the top management. In contrast to the Dantzig/Wolfe situation, however, all decision makers - on the top- as well as on the base-level - are assumed to have more than one goal. Therefore, within the process of production planning a hierarchical negotiation between top- and base-level takes place, in which interpersonel as well as intrapersonel conflicts have to be solved. The well-known interactive MODM algorithm of Zionts/Wallenius is modified in order to structure the hierarchical negotiation and to model its hierarchical character. The negotiation results in a feasible resource allocation and in a set of aspiration levels for the goals of the top-level which have to be met by the different divisions. (C) 1998 Elsevier Science B.V. All rights reserved.
Vendor selection decisions are typically multi-objective in nature. In an environment of competing vendors for a product or service, some vendors are selected and some are not. This paper describes three approaches fo...
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Vendor selection decisions are typically multi-objective in nature. In an environment of competing vendors for a product or service, some vendors are selected and some are not. This paper describes three approaches for the selection and negotiation with vendors who were not selected. Furthermore, it describes how in certain situations two multi-criteria analysis tools, multi-objective programming and data envelopment analysis, can be used together for this selection and negotiation process. The paper describes non-cooperative vendor negotiation strategies where the selection of one vendor results in another being left out of the solution. (C) 1998 Elsevier Science B.V.
The classical 0-1 knapsack problem is considered with two objectives. Two methods of the "two-phases" type are developed to generate the set of efficient solutions. In the first phase, the set of supported e...
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The classical 0-1 knapsack problem is considered with two objectives. Two methods of the "two-phases" type are developed to generate the set of efficient solutions. In the first phase, the set of supported efficient solutions is determined by optimizing a parameterized single-objective knapsack problem. Two versions are proposed for a second phase, determining the non-supported efficient solutions: both versions are Branch and Bound approaches, but one is "breadth first", while the other is "depth first". Extensive numerical experiments have been realized to compare the results of both methods.
Cable-stayed bridges are gaining much popularity in Japan due to their beautiful shape. During and after construction, this kind of bridge needs to have the cable length adjusted in order to attain errors of cable ten...
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Cable-stayed bridges are gaining much popularity in Japan due to their beautiful shape. During and after construction, this kind of bridge needs to have the cable length adjusted in order to attain errors of cable tension and camber within some allowable range. This problem becomes a multi-objective optimization, and has been tried to be solved by traditional goal programming with a squared sum of objective functions as a scalarization function. Several authors, including one of the authors of this paper, reported, however, that it is not so easy to obtain a desirable solution by adjusting weights as in goal programming, On the other hand, the aspiration level approach to multi-objective programming problems is now widely recognized to be effective in many practical fields, because it is very simple and easy to implement, and does not require any mathematical consistency for the judgment of decision makers, and moreover uses the aspiration level of decision makers as a probe rather than weights for objective functions. The authors developed a user-friendly software for construction accuracy control of cable-stayed bridges using a multiobjectiveprogramming technique, called the satisficing trade-off method, and applied it to some real bridges, In this paper, we report our experiences of real applications of the multi-objective programming technique to construction accuracy control of cable-stayed bridges.
According to Hainan Island's biological characteristics, and existing structure of productivity of tropical crops and local climatic conditions, this paper carries on regional division of tropical crops by fuzzy m...
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According to Hainan Island's biological characteristics, and existing structure of productivity of tropical crops and local climatic conditions, this paper carries on regional division of tropical crops by fuzzy mathematics. Based on calculation of basic parameters for tl1e formation of production, near-tem optimum models of tropical crops structure of each region was established by means of multi-objective programming, and a far-term grey programming model was set up through the above-mentioned near-term model and prediction of future parameters. Conclusion shows that the near-term programming may raise the profit by 5. 1-55.7 percent and far-tem programming by 54-90 percent, both gainingobvious economic benefits.
This paper demonstrates the utility of multi-objective programming techniques as an aid in educational planning and the limitations to the achievement of any educational objective given the spatial distribution of exi...
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This paper demonstrates the utility of multi-objective programming techniques as an aid in educational planning and the limitations to the achievement of any educational objective given the spatial distribution of existing disparities. A case study of Connecticut is used to examine alternative scenarios for the implementation of interdistrict responses to a number of issues facing the state's public education system. A mixed-integer, goal programming model is formulated where the goal constraints are to minimize disparities in: (1) minority enrollments, (2) grand-list/student ratios, (3) student-teacher ratios, and (4) overall enrollment. Results show that the traditional distance-minimizing or transportation-minimizing objectives are in conflict with all other aims of equity and quality of educational opportunities. The geographic distribution of minority students and grand-list property values also limited the reduction of statewide disparities in these goals.
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