With economic development, a great amount of hazardous material is shipped in the transport network every day. Hazardous material transportation is well known for its high potential risk. An accident can cause very se...
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With economic development, a great amount of hazardous material is shipped in the transport network every day. Hazardous material transportation is well known for its high potential risk. An accident can cause very serious economic damage and will have a negative impact on public health and the environment over the long term. Transporting hazardous materials on special lanes can reduce the risk. However, a lane reservation strategy may worsen traffic conditions for other vehicles. This paper investigates a hazardous material transportation problem with lane reservation. The problem lies in how to choose lanes to be reserved in the network and select the path for each hazardous material shipment from the reserved lanes. The goal is to obtain the best compromise between the impact on normal traffic and the transportation risk. A multiobjective integer programming model is presented for the new problem. Then, an algorithm is developed based on the epsilon-constraint method and a fuzzy-logic-based approach. Pareto optimal solutions are obtained by the former, and a preferred solution is selected by the fuzzy-logic-based approach. Computational results demonstrate the efficiency of the proposed algorithm using an instance based on a real network topology and randomly generated instances.
It is well known that Brazil is the largest producer of sugarcane in the world. Nevertheless, a great concern exists about the crop system used, because the most common practice is manual harvesting with prior straw b...
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It is well known that Brazil is the largest producer of sugarcane in the world. Nevertheless, a great concern exists about the crop system used, because the most common practice is manual harvesting with prior straw burning. The Brazilian authorities have approved a law prohibiting the burning of sugarcane crop residue before harvesting. However, mechanized harvesting creates the new problem of having to deal with the residue. Many studies have indeed proposed the use of this residue as an energy source. A major difficulty in using this residue is how to economically transport sugarcane harvest biomass from a farm to a processing centre. Besides transport costs, another concern is knowing whether the energy generated by the straw offsets the energy used, in terms of fuel, in the process. This study proposes a multiobjectiveinteger linear programming optimization model to choose sugarcane varieties so as to minimize costs in the use of crop residue and simultaneously maximize the energy balance in such a process. Computational results are presented and discussed.
The generalized assignment problem (GAP) has found applications in many real world problems. In this paper, we examine the GAP from a multiobjective point of view to accommodate some real world situations where more t...
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The generalized assignment problem (GAP) has found applications in many real world problems. In this paper, we examine the GAP from a multiobjective point of view to accommodate some real world situations where more than one objective is involved. An efficient LP-based heuristic is proposed to solve the biobjective generalized assignment problem (BiGAP). Extensive computational experiments are carried out to evaluate the performance of the proposed method. The results show that the proposed approach is able to generate good approximations to the nondominated frontier of the BiGAP efficiently, especially when the ratio of the number of items to the number of knapsacks is large. (C) 2006 Elsevier Ltd. All rights reserved.
The use of "surrogate" design criteria (such as size or connectedness) to evaluate potential bioreserve network alternatives is attractive because they can be relatively straightforward to measure. However, ...
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The use of "surrogate" design criteria (such as size or connectedness) to evaluate potential bioreserve network alternatives is attractive because they can be relatively straightforward to measure. However, to promote the persistence of a focal species, a higher level of biological detail may be used to derive specific design criteria for the species of interest. But just as for surrogate criteria, no single best criterion is likely to arise. Here, a set of mechanistic equations describing the dynamics of hawks and voles in a hypothetical landscape is used to derive design criteria for a reserve network. multiobjective integer programming (MOIP) then identifies reserve network alternatives that reflect the tradeoffs between the objectives. When choosing from only five potential patches for inclusion in the network, in four of five cases a single design optimized the design objectives simultaneously. When choosing from ten patches, in all five cases there were conflicts between the objectives, but in two of five cases, there were optimal intermediate solutions along the tradeoff surface between the objectives. When resources allow, a more detailed description of the species of conservation interest may be used to develop reserve design criteria that are likely to promote persistence. MOIP can then be used to evaluate potential compromises between the criteria.
The paper presents a bi-objective integer program and an approximative lexicographic approach for a bicriterion loading and routing problem in a flexible assembly system. The problem objective is to determine an alloc...
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The paper presents a bi-objective integer program and an approximative lexicographic approach for a bicriterion loading and routing problem in a flexible assembly system. The problem objective is to determine an allocation of tasks among the assembly stations for a set of products so as to balance station workloads and minimize total interstation transfer time. In the approach proposed, first the station workloads are balanced using a linear relaxation-based heuristic and then assembly routes are selected based on a network flow model. An illustrative example is provided and some results of computational experiments are reported. (C) 1998 Elsevier Science B.V.
This paper presents integerprogramming formulations and an interactive solution procedure for a bicriterion loading problem in a flexible assembly system. The system is made up of a set of assembly stations linked wi...
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This paper presents integerprogramming formulations and an interactive solution procedure for a bicriterion loading problem in a flexible assembly system. The system is made up of a set of assembly stations linked with an automated material handling system. In the system, several different product types can be assembled simultaneously. The problem objective is to assign assembly tasks and products to stations with limited working space, so as to balance the station workloads and to minimize station-to-station product transfer time, subject to precedence relations among the tasks for a mix of product types. The solution procedure proposed is based on the weighting method and the interactive search for a set of weights which would produce the most preferred nondominated solution. Numerical examples are included to illustrate possible applications of the interactive approach for various problem formulations proposed.
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