This paper describes the ring spur assignment problem (RSAP), a new problem arising in the design of next generation networks. The RSAP complements the sonet ring assignment problem (SRAP). We describe the RSAP, posit...
详细信息
This paper describes the ring spur assignment problem (RSAP), a new problem arising in the design of next generation networks. The RSAP complements the sonet ring assignment problem (SRAP). We describe the RSAP, positioning it in relation to problems previously addressed in the literature. We decompose the problem into two IP problems and describe a branch-and-cut decomposition heuristic algorithm suitable for solving problem instances in a reasonable time. We present promising computational results.
Facility location problem is one of the strategic logistical drivers within the supply chain which is a hard to solve optimization problem. In this study, we focus on the uncapacitated single-source multi-product prod...
详细信息
Facility location problem is one of the strategic logistical drivers within the supply chain which is a hard to solve optimization problem. In this study, we focus on the uncapacitated single-source multi-product production/distribution facility location problem with the presence of set-up cost. To efficiently tackle this decision problem, two Lagrangian-based heuristics are proposed one of which incorporates integer cuts to strengthen the formulation. Local search operators are also embedded within these methods to improve the upper bounds as the search progresses. Three sets of instances with various characteristics are generated and used to evaluate the performance of the proposed algorithms. Encouraging results are obtained when assessed against an ILP formulation using CPLEX. The latter is used for generating optimal solutions for small size instances and also as a means for producing upper and lower bounds for larger ones when restricted by a limited amount of execution time. (C) 2013 Elsevier B.V. All rights reserved.
An extended variant of Location-Routing Problem namely LRP with Multi-Product and Pickup and Delivery (LRP-MPPD) is considered in this study. The proposed model deals with simultaneously selecting (locating) one or mo...
详细信息
ISBN:
(纸本)9781479903139;9781479903146
An extended variant of Location-Routing Problem namely LRP with Multi-Product and Pickup and Delivery (LRP-MPPD) is considered in this study. The proposed model deals with simultaneously selecting (locating) one or more facilities from a set of potential hub (locations), assigning customers to the selected hubs and defining routes of the vehicles for serving multi-product customers demand in such way that each selected hub must be visited once for delivering, though they can be visited many times for picking up. We propose a mixed integer linear programmingformulation and a heuristic approach for this problem. Since there is not any instance compatible with LRP-MPPD in the literature, we have extended known LRP instances to evaluate the performance of the proposed approach. A comparison with CPLEX shows that the proposed algorithm is a viable approach to solve small and large size LRP-MPPD instances.
An extended variant of Location-Routing Problem namely LRP with Multi-Product and Pickup and Delivery (LRP-MPPD) is considered in this study. The proposed model deals with simultaneously selecting (locating) one or mo...
详细信息
ISBN:
(纸本)9781479903146
An extended variant of Location-Routing Problem namely LRP with Multi-Product and Pickup and Delivery (LRP-MPPD) is considered in this study. The proposed model deals with simultaneously selecting (locating) one or more facilities from a set of potential hub (locations), assigning customers to the selected hubs and defining routes of the vehicles for serving multi-product customers demand in such way that each selected hub must be visited once for delivering, though they can be visited many times for picking up. We propose a mixed integer linear programmingformulation and a heuristic approach for this problem. Since there is not any instance compatible with LRP-MPPD in the literature, we have extended known LRP instances to evaluate the performance of the proposed approach. A comparison with CPLEX shows that the proposed algorithm is a viable approach to solve small and large size LRP-MPPD instances.
Background: A bisection-type algorithm for the grammar-based compression of tree-structured data has been proposed recently. In this framework, an elementary ordered-tree grammar (EOTG) and an elementary unordered-tre...
详细信息
Background: A bisection-type algorithm for the grammar-based compression of tree-structured data has been proposed recently. In this framework, an elementary ordered-tree grammar (EOTG) and an elementary unordered-tree grammar (EUTG) were defined, and an approximation algorithm was proposed. Results: In this paper, we propose an integerprogramming-based method that finds the minimum context-free grammar (CFG) for a given string under the condition that at most two symbols appear on the right-hand side of each production rule. Next, we extend this method to find the minimum EOTG and EUTG grammars for given ordered and unordered trees, respectively. Then, we conduct computational experiments for the ordered and unordered artificial trees. Finally, we apply our methods to pattern extraction of glycan tree structures. Conclusions: We propose integerprogramming-based methods that find the minimum CFG, EOTG, and EUTG for given strings, ordered and unordered trees. Our proposed methods for trees are useful for extracting patterns of glycan tree structures.
Background: RNA secondary structure prediction is one major task in bioinformatics, and various computational methods have been proposed so far. Pseudoknot is one of the typical substructures appearing in several RNAs...
详细信息
Background: RNA secondary structure prediction is one major task in bioinformatics, and various computational methods have been proposed so far. Pseudoknot is one of the typical substructures appearing in several RNAs, and plays an important role in some biological processes. Prediction of RNA secondary structure with pseudoknots is still challenging since the problem is NP-hard when arbitrary pseudoknots are taken into consideration. Results: We introduce a new method of predicting RNA secondary structure with pseudoknots based on integerprogramming. In our formulation, we aim at minimizing the value of the objective function that reflects free energy of a folding structure of an input RNA sequence. We focus on a practical class of pseudoknots by setting constraints appropriately. Experimental results for a set of real RNA sequences show that our proposed method outperforms several existing methods in sensitivity. Furthermore, for a set of sequences of small length, our approach achieved good performance in both sensitivity and specificity. Conclusion: Our integerprogramming-based approach for RNA structure prediction is flexible and extensible.
This paper deals with short-term scheduling of the dairy industry. Two different approaches are proposed for obtaining the minimal makespan schedules. According to the first, S-graph framework is proposed to find the ...
详细信息
This paper deals with short-term scheduling of the dairy industry. Two different approaches are proposed for obtaining the minimal makespan schedules. According to the first, S-graph framework is proposed to find the optimal solution of the flow-shop scheduling problem. The problem is solved by applying the branch and bound technique. The second approach uses the integer programming formulation of the scheduling problem and BASIC genetic algorithm has been used to solve the optimization problem. Both approaches take into consideration volumes of units assigned to perform tasks, and respective size factors that affect the size of batches and their number must be produces to achieve production goals and thus on the schedules duration. Manufacturing of two type curds is used as a case study. The results obtained show that both approaches provide comparable solutions. Both approaches could be seen as a good alternative to project manager to find appropriate schedule of the dairy industry.
In this article, we consider the two 4-hop-constrained paths problem, which consists, given a graph G = (N, E) and two nodes s, t is an element of N, of finding a minimum cost sub-graph in G containing at least two no...
详细信息
In this article, we consider the two 4-hop-constrained paths problem, which consists, given a graph G = (N, E) and two nodes s, t is an element of N, of finding a minimum cost sub-graph in G containing at least two node- (resp., edge-) disjoint paths of length at most 4 between s and t. We give integer programming formulations, in the space of the design variables, for both the node and edge versions of this problem. (c) 2006 Wiley Periodicals, Inc.
We discuss the problem of sequencing precedence-constrained jobs on a single machine to minimize the average weighted completion time. This problem has attracted much attention in the mathematical programming communit...
详细信息
We discuss the problem of sequencing precedence-constrained jobs on a single machine to minimize the average weighted completion time. This problem has attracted much attention in the mathematical programming community since Sidney's pioneering work in 1975 (Sidney, J. B. 1975. Decomposition algorithms for single machine scheduling with precedence relations and deferral costs. Operations Research 23 283-298). We look at the problem from a polyhedral perspective and uncover a relation between Sidney's decomposition theorem and different linear programming relaxations. More specifically, we present a generalization of Sidney's result, which particularly allows us to reason that virtually all known 2-approximation algorithms are consistent with his decomposition. Moreover, we establish a connection between the single-machine scheduling problem and the vertex cover problem. Indeed, in the special case of series-parallel precedence constraints, we prove that the sequencing problem can be seen 'as a special case of the vertex cover problem. We also. argue that this result is true for general precedence constraints if one can show that a certain integer program represents a valid formulation of the sequencing problem. Finally, we give a 3/2-approximation algorithm for two-dimensional partial orders, and we also provide a characterization of the active inequalities of a linear programming relaxation in completion time variables.
暂无评论