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1.
In this paper we develop a segmentation scheme for digital images based upon an iterative binary coloring technique that takes into account changing behavior of adjacent pixels. The output is a hierarchical structure of images which allows a better understanding of complex images. In particular, we propose two algorithms that should be considered as image preprocessing techniques. 相似文献
2.
《Omega》2015
Motivated by a proposal of the local authority for improving the existing healthcare system in the Parana State in Brazil, this article presents an optimization-based model for developing a better system for patients by aggregating various health services offered in the municipalities of Parana into some microregions. The problem is formulated as a multi-objective partitioning of the nodes of an undirected graph (or network) with the municipalities as the nodes and the roads connecting them as the edges of the graph. Maximizing the population homogeneity in the microregions, maximizing the variety of medical procedures offered in the microregions, and minimizing the inter-microregion distances to be traveled by patients are considered as three objective functions of the problem. An integer-coded multi-objective genetic algorithm is adopted as the optimization tool, which yields a significant improvement to the existing healthcare system map of the Parana State. The results obtained may have a strong impact on the healthcare system management in Parana. The model proposed here could be a useful tool to aid the decision-making in health management, as well as for better organization of any healthcare system, including those of other Brazilian States. 相似文献
3.
Bernard Gendron Alain Hertz Patrick St-Louis 《Journal of Combinatorial Optimization》2007,13(2):163-178
We consider the problem of orienting the edges of a graph so that the length of a longest path in the resulting digraph is
minimum. As shown by Gallai, Roy and Vitaver, this edge orienting problem is equivalent to finding the chromatic number of
a graph. We study various properties of edge orienting methods in the context of local search for graph coloring. We then
exploit these properties to derive four tabu search algorithms, each based on a different neighborhood. We compare these algorithms
numerically to determine which are the most promising and to give potential research directions. 相似文献
4.
Journal of Combinatorial Optimization - Keyword-aware optimal route queries are a combinatorial optimization problem with three factors, namely keyword coverage, route budget constraint and route... 相似文献
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6.
This paper discusses the relation among four problems: graph testing, DNA complex screening, superimposed codes and secure
key distribution. We prove a surprising equivalence relation among these four problems, and use this equivalence to improve
current results on graph testing. In the rest of this paper, we give a lower bound for the minimum number of tests on DNA
complex screening model.
The first and second author would like to dedicate this paper to professor Frank K. Hwang on the occasion of his 65th birthday.
This research is partially supported by Republic of China, National Science Council grant NSC 92-2115-M-009-014. 相似文献
7.
一种改进的TSP问题启发式算法 总被引:6,自引:0,他引:6
旅行推销商问题(TSP)属于组合优化领域中一个典型的NP Hard问题。本文在最近城市搜索法的基础上,提出一种改进的启发式算法———两端延伸最近城市搜索法,这种方法能够很快得到最优解(近优解),且大大降低了计算复杂度。同时,对TSP问题进行了分类,并给出相应的启发式解法。 相似文献
8.
Young-Soo Myung 《生产规划与管理》2013,24(3):339-342
Lee et al. (Lee, K., Chang, S.Y., and Hong, Y., 2004. Continuous slab caster scheduling and interval graphs. Production Planning & Control, 13 (5), 495–501) have introduced a slab caster scheduling problem and developed an optimal algorithm. Their algorithm is efficient but an offline algorithm that we need the information on all the customer orders a priori to implement. In this article, we propose an online algorithm that we can implement without knowledge of the orders yet to arrive. We show that the offline version of our new algorithm also provides an optimal solution and the online version has the worst case performance ratio of 3. We also give a short proof on the correctness of Lee et al.'s algorithm. 相似文献
9.
《Omega》2017
We study a real-world production warehousing case, where the company always faces the challenge to find available space for its products and to manage the items in the warehouse. To resolve the problem, an integrated strategy that combines warehouse layout with the capacitated lot-sizing problem is presented, which have been traditionally treated separately in the existing literature. We develop a mixed integer linear programming model to formulate the integrated optimization problem with the objective of minimizing the total cost of production and warehouse operations. The problem with real data is a large-scale instance that is beyond the capability of optimization solvers. A novel Lagrangian relax-and-fix heuristic approach and its variants are proposed to solve the large-scale problem. The preliminary numerical results from the heuristic approaches are reported. 相似文献
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11.
Prahalad Venkateshan Kamlesh Mathur Ronald H. Ballou 《Journal of Combinatorial Optimization》2008,15(4):315-341
Fang and Qi (Optim. Methods Softw. 18:143–165, 2003) introduced a new generalized network flow model called manufacturing network flow model for manufacturing process modeling.
A key distinguishing feature of such models is the assembling of component raw-materials, in a given proportion, into an end-product. This assembling operation cannot be modeled using usual generalized networks (which allow gains and
losses in flows), or using multi-commodity networks (which allow flows of multiple commodity types on a single arc). The authors
developed a network-simplex-based algorithm to solve a minimum cost flow problem formulated on such a generalized network
and indicated systems of linear equations that need to be solved during the course of the network-simplex-based solution procedure.
In this paper, it is first shown how various steps of the network-simplex-based solution procedure can be performed efficiently
using appropriate data structures. Further, it is also shown how the resulting system of linear equations can be solved directly
on the generalized network. 相似文献
12.
Assembly lines are usually constructed as the last stage of the entire production system and efficiency of an assembly line is one of the most important factors which affect the performance of a complex production system. The main purpose of this paper is to mathematically formulate and to provide an insight for modelling the parallel two-sided assembly line balancing problem, where two or more two-sided assembly lines are constructed in parallel to each other. We also propose a new genetic algorithm (GA)-based approach in alternatively to the existing only solution approach in the literature, which is a tabu search algorithm. To the best of our knowledge, this is the first formal presentation of the problem as well as the proposed algorithm is the first attempt to solve the problem with a GA-based approach in the literature. The proposed approach is illustrated with an example to explain the procedures of the algorithm. Test problems are solved and promising results are obtained. Statistical tests are designed to analyse the advantage of line parallelisation in two-sided assembly lines through obtained test results. The response of the overall system to the changes in the cycle times of the parallel lines is also analysed through test problems for the first time in the literature. 相似文献
13.
Vincenzo Cutello Giuseppe Nicosia Mario Pavone 《Journal of Combinatorial Optimization》2007,14(1):9-33
We present a new Immune Algorithm, IMMALG, that incorporates a Stochastic Aging operator and a simple local search procedure to improve the overall performances in
tackling the chromatic number problem (CNP) instances. We characterize the algorithm and set its parameters in terms of Kullback
Entropy. Experiments will show that the IA we propose is very competitive with the state-of-art evolutionary algorithms. 相似文献
14.
Glenn W. Suter II Barney W. Cornaby Charles T. Hadden Ruth N. Hull Mark Stack Fred A. Zafran 《Risk analysis》1995,15(2):221-231
Human health and ecological risks must be balanced at hazardous waste sites in order to ensure that remedial actions prevent unacceptable risks of either type. Actions that are designed to protect humans may fail to protect nonhuman populations and ecosystems or may damage ecosystems. However, there is no common scale of health and ecological risk that would allow comparisons to be performed. This paper presents an approach to addressing this problem based on classifying all risks (i.e., health and ecological risks due contaminants and remediation) as insignificant ( de minimis ), highly significant ( de manifestis ), or intermediate. For health risks the classification is based on standard criteria. However, in the absence of national guidance concerning the acceptability of ecological risks, new ecological criteria are proposed based on an analysis of regulatory precedents. Matrices and flow charts are presented to guide the use of these risk categories in remedial decision making. The assessment of mercury contamination of the East Fork Poplar Creek is presented as an example of the implementation of the approach. 相似文献
15.
In this paper, an efficient tabu search algorithm is prepared for solving the single-machine mean tardiness problem. The proposed implementation of the tabu search approach suggests simple techniques for generating neighbourhoods of a given sequence and a combined scheme for intensification and diversification. The tabu search method is shown to produce results very close to the optimal solution using randomly generated problems with varying degrees of difficulty. 相似文献
16.
一种求解时变条件下有宵禁限制最短路的算法 总被引:1,自引:0,他引:1
在组合优化过程中,往往需要获得从起点到终点之间的最短路.由于道路、天气、交通条件等因素的影响,使得网络具有很强的时变特性.同时,对于网络中的节点往往有宵禁的限制.对时变条件下有宵禁限制并有到达时间限制的最短路进行了研究,建立了软、硬宵禁限制下的数学模型,给出并证明了时变条件下获得有宵禁限制最短路的最优条件,并设计了求解的多项式算法,通过此算法可以获得时变条件下有宵禁限制的最短路.同时,算法和模型还考虑了不同的起点出发时间,使路径决策者可以根据自身的情况,选择合适的出发时间和路径.最后给出了一个应用算例,分析了宵禁对于获得的最短路的影响. 相似文献
17.
This paper investigates and suggests an efficient solution to the problem of scheduling the steel making line in the Mini Steel Mill, which consists of three major processes: molten steel making, continuous slab casting, and hot charged rolling. Careful synchronization of these processes is a key productivity factor, since a very limited amount of work-in-process inventory is allowed. Since each process must run in batch, the schedule for the Mini-Mill consists of grouping and sequencing of lots for each process. However, each process has its own criteria for judging the quality of its lot grouping, which often conflicts with other processes. An efficient scheduling algorithm for the Mini-Mill is proposed. Numerical experiments with real world data suggest that the proposed algorithm yield satisfactory schedules very efficiently. The algorithm is currently used for the actual scheduling of a Mini-Mill in Korea. 相似文献
18.
《Omega》2016
In the global competitive environment, lead companies have to outsource their manufacturing to electronic contract manufacturers (ECM) in order to reduce operational cost and capture higher profit. Thus, the process of selecting contract manufacturers to be strategic partners is important for these companies. For this reason, this paper proposes an integrated approach for the electronic contract manufacturer selection problem, combining the voting method and the goal programming (GP) model to take into account quantitative factors involved in the selection process, which is applied to a real-world ECM selection problem encountered by a leading provider of complete broadband access solutions. Results of the case study indicate that the voting method can acquire the rating information quickly from manufacturing managers based on suitable evaluating criteria. The rating information simultaneously incorporates ECMs' performance scores as a weight for each ECM. A production planner can easily employ the GP model and ECMs’ weight information to effectively assign demand quantities to ECMs. Therefore, the integrated approach is a practical and useful tool for solving the contract manufacturer selection problem. 相似文献
19.
Diego Recalde Daniel Severín Ramiro Torres Polo Vaca 《Journal of Combinatorial Optimization》2018,36(3):916-936
In this work a balanced k-way partitioning problem with weight constraints is defined to model the sports team realignment. Sports teams must be partitioned into a fixed number of groups according to some regulations, where the total distance of the road trips that all teams must travel to play a double round robin tournament in each group is minimized. Two integer programming formulations for this problem are introduced, and the validity of three families of inequalities associated to the polytope of these formulations is proved. The performance of a tabu search procedure and a branch and cut algorithm, which uses the valid inequalities as cuts, is evaluated over simulated and real-world instances. In particular, an optimal solution for the realignment of the Ecuadorian football league is reported and the methodology can be suitable adapted for the realignment of other sports leagues. 相似文献
20.
Nowadays, reverse logistics is gaining importance for many companies in different industries. This importance is rooted in the fact that it generates profit and decreases the environmental impacts of products. Even though the decrease of environmental impacts is an indispensable requisite, reverse logistics design is only driven by cost indicators. The main reason behind this high cost is access to environmental information is difficult and is directly linked to data all along the lifecycle of the product. This paper presents a method by which reverse logistics design integrates environmental impacts based on the management of closed-loop product lifecycle. This method is divided into two processes: from beginning of life to end of life and from end of life to beginning of life. The first process integrates product data in order to calculate environmental impacts of the potential reverse logistics networks, whereas the second process selects the most appropriate reverse logistics network before optimising the product based on this particular network. The proposition is illustrated by a case study on a recycled aluminium automotive part. 相似文献