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Efficiently Solving the Redundancy Allocation Problem Using Tabu Search
, 2003
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Crane Scheduling with Spatial Constraints: Mathematical Model and Solving Approaches
 NAVAL RESEARCH LOGISTICS
, 2004
"... In this paper, we examine crane scheduling for ports. This important component of port operations management is studied when the noncrossing spatial constraint, which is common to crane operations, are considered. Our objective is to minimize the latest completion time for all jobs, which is a w ..."
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Cited by 19 (0 self)
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In this paper, we examine crane scheduling for ports. This important component of port operations management is studied when the noncrossing spatial constraint, which is common to crane operations, are considered. Our objective is to minimize the latest completion time for all jobs, which is a widely used criteria in practice. We provide the proof that this problem is NPcomplete and design a branchandbound algorithm to obtain optimal solutions. A simulated annealing metaheuristic with effective neighborhood search is designed to find good solutions in larger size instances. The elaborate experimental results show that the branchandbound algorithm runs much faster than CPLEX and the simulated annealing approach can obtain near optimal solutions for instances of various sizes.
The ring star problem: polyhedral analysis and exact algorithm
 NETWORKS
, 2004
"... In the Ring Star Problem, the aim is to locate a simple cycle through a subset of vertices of a graph with the objective of minimizing the sum of two costs: a ring cost proportional to the length of the cycle and an assignment cost from the vertices not in the cycle to their closest vertex on the cy ..."
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Cited by 18 (1 self)
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In the Ring Star Problem, the aim is to locate a simple cycle through a subset of vertices of a graph with the objective of minimizing the sum of two costs: a ring cost proportional to the length of the cycle and an assignment cost from the vertices not in the cycle to their closest vertex on the cycle. The problem has several applications in telecommunications network design and in rapid transit systems planning. It is an extension of the classical location–allocation problem introduced in the early 1960s, and closely related versions have been recently studied by several authors. This article formulates the problem as a mixedinteger linear program and strengthens it with the introduction of several families of valid inequalities. These inequalities are shown to be facetdefining and are used to develop a branchandcut algorithm. Computational results show that instances involving up to 300 vertices can be solved optimally using the proposed methodology.
Gonzàlez. The capacitated mring star problem
 Operations Research
"... The Capacitated mRingStar Problem (CmRSP) is the problem of designing a set of rings that pass through a central depot and through some transition points and/or customers, and then assigning each nonvisited customer to a visited point or customer. The number of customers visited and assigned to ..."
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The Capacitated mRingStar Problem (CmRSP) is the problem of designing a set of rings that pass through a central depot and through some transition points and/or customers, and then assigning each nonvisited customer to a visited point or customer. The number of customers visited and assigned to a ring is bounded by an upper limit: the capacity of the ring. The objective is to minimize the total routing cost plus assignment costs. The problem has practical applications in the design of urban optical telecommunication networks. This paper presents and discusses two integer programming formulations for the CmRSP. Valid inequalities are proposed to strengthen the linear programming relaxation, and are used as cutting planes in a branchandcut approach. The procedure is implemented and tested on a large family of instances, including realworld instances, and the good performance of the proposed approach is demonstrated. Subject classifications: Networks/graphs: optical network design. Programming, integer, cutting plane: Branchandcut algorithm.
Metaheuristics and cooperative approaches for the Biobjective Ring Star Problem, in "Computers
 Operations Research
"... This paper presents and investigates different approaches to solve a new biobjective routing problem called the ring star problem. It consists of locating a simple cycle through a subset of nodes of a graph while optimizing two kinds of cost. The first objective is the minimization of a ring cost t ..."
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This paper presents and investigates different approaches to solve a new biobjective routing problem called the ring star problem. It consists of locating a simple cycle through a subset of nodes of a graph while optimizing two kinds of cost. The first objective is the minimization of a ring cost that is related to the length of the cycle. The second one is the minimization of an assignment cost from nonvisited nodes to visited ones. In spite of its obvious biobjective formulation, this problem has always been investigated in a singleobjective way. To tackle the biobjective ring star problem, we first investigate different standalone search methods. Then, we propose two cooperative strategies that combine two multiobjective metaheuristics: an elitist evolutionary algorithm and a populationbased local search. We apply these new hybrid approaches to wellknown benchmark test instances and demonstrate their effectiveness in comparison to nonhybrid algorithms and to stateoftheart methods.
TABU SEARCH IN THE REDUNDANCY ALLOCATION OPTIMIZATION FOR MULTISTATE SERIESPARALLEL SYSTEMS
"... In this paper, a tabu search for solving the redundancy allocation problem (RAP) in multistates (different performance levels) seriesparallel systems (MSPS) is proposed. The problem is modeled to find the optimal system configuration that minimizes the cost of the component selection and redundanc ..."
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In this paper, a tabu search for solving the redundancy allocation problem (RAP) in multistates (different performance levels) seriesparallel systems (MSPS) is proposed. The problem is modeled to find the optimal system configuration that minimizes the cost of the component selection and redundancy level under given minimum required system reliability constraints. The proposed solution methodology offers several benefits compared with other approaches. The computational results demonstrate advantages of the proposed approach for solving this type of problem.