In this paper we present a novel groupinggenetic algorithm for clustering problems. Though there have been different approaches that have analyzed the performance of several genetic and evolutionary algorithms in clu...
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In this paper we present a novel groupinggenetic algorithm for clustering problems. Though there have been different approaches that have analyzed the performance of several genetic and evolutionary algorithms in clustering, the grouping-based approach has not been, to our knowledge, tested in this problem yet. In this paper we fully describe the groupinggenetic algorithm for clustering, starting with the proposed encoding, different modifications of crossover and mutation operators, and also the description of a local search and an island model included in the algorithm, to improve the algorithm's performance in the problem. We test the proposed groupinggenetic algorithm in several experiments in synthetic and real data from public repositories, and compare its results with that of classical clustering approaches, such as K-means and DBSCAN algorithms, obtaining excellent results that confirm the goodness of the proposed grouping-based methodology. (C) 2012 Elsevier Ltd. All rights reserved.
In this paper we present a novel grouping harmony search algorithm for the Access Node Location Problem (ANLP) with different types of concentrators. The ANLP is a NP-hard problem where a set of distributed terminals,...
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In this paper we present a novel grouping harmony search algorithm for the Access Node Location Problem (ANLP) with different types of concentrators. The ANLP is a NP-hard problem where a set of distributed terminals, with distinct rate demands, must be assigned to a variable number of concentrators subject to capacity constraints. We consider the possibility of choosing between different concentrator models is given in order to provide service demand at different cost. The ANLP is relevant in communication networks design, and has been considered before within the design of MPLS networks, for example. The approach we propose to tackle the ANLP problem consists of a hybrid grouping Harmony Search (GHS) algorithm with a local search method and a technique for repairing unfeasible solutions. Moreover, the presented scheme also includes the adaptation of the GHS to a differential scheme, where each proposed harmony is obtained from the same harmony in the previous iteration. This differential scheme is perfectly adapted to the specifications of the ANLP problem, as it utilizes the grouping concept based on the proximity between nodes, instead of being only based on the grouping concept. This allows for a higher efficiency on the searching process of the algorithm. Extensive Monte Carlo simulations in synthetic instances show that this proposal provides faster convergence rate, less computational complexity and better statistical performance than alternative algorithms for the ANLP, such as grouping genetic algorithms, specially when the size of the scenario increases. We also include practical results for the application of GHS to a real wireless network deployment problem in Bizkaia, northern Spain. (C) 2011 Elsevier Ltd. All rights reserved.
This paper presents a new model for team formation based on group technology (TFPGT). Specifically, the model is applied as a generalization of the well-known Machine-Part Cell Formation problem, which has become a cl...
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This paper presents a new model for team formation based on group technology (TFPGT). Specifically, the model is applied as a generalization of the well-known Machine-Part Cell Formation problem, which has become a classical problem in manufacturing in the last few years. In this case, the model presented is especially well-suited for problems of team formation arising in R&D-oriented or teaching institutions. A parallel hybrid groupinggenetic algorithm (HGGA) is also proposed in the paper to solve the TFPGT. The performance of the algorithm is shown in several synthetic TFPGT instances, and in a real problem: the formation of teaching groups at the Department of Signal Theory and Communications of the Universidad de Alcala in Spain. (C) 2010 Elsevier Ltd. All rights reserved.
Recently, people all over the world have paid much attention to green and environmental design. The proposal of design for end of life is to take into account the recycling problem in the product design stage. Under t...
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Recently, people all over the world have paid much attention to green and environmental design. The proposal of design for end of life is to take into account the recycling problem in the product design stage. Under the consideration of economy, the green recycle of a product depends upon the relationship between recycling profit and recycling cost of the discarded product. This study attempted to build up a disassembly-oriented assessment method for product modular design in four stages. At Stage 1, the liaison intensity was used to quantify the connection relations among parts by their engineering information. At Stage 2, the product to be recycled was modularised by the grouping genetic algorithms. At Stage 3, the disassembly cost and recycle profit of the modules were evaluated. At Stage 4, an interference matrix was used to specify the disassembly sequential order of product modules and parts. Finally, the stapler was used as an example to illustrate the proposed assessment methodology.
This paper presents a novel application of the hybrid groupinggenetic algorithm in a problem related to university timetabling. Specifically, the assignment of students to laboratory groups is tackled. This problem i...
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This paper presents a novel application of the hybrid groupinggenetic algorithm in a problem related to university timetabling. Specifically, the assignment of students to laboratory groups is tackled. This problem includes an important constraint of capacity, due to laboratories usually have a maximum number of equips or computers available. so the number of total students in a group is constrained to be equal or less than the capacity of the laboratory. In addition, our approach considers the case in which the students provide a sorted list of preferred laboratory groups, so the objective of the assignment must take this point into account. A variation of the problem in which a balanced number of students per group is required (lecturer preferences) is also studied in this paper. The performance of the approach is shown in different test problems and in a real application in a Spanish University. (C) 2008 Elsevier Ltd. All rights reserved.
Assembly sequence planning (ASP) and assembly line balancing (ALB) play critical roles in designing product assembly systems. In view of the trend of concurrent engineering, pondering simultaneously over these two pro...
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Assembly sequence planning (ASP) and assembly line balancing (ALB) play critical roles in designing product assembly systems. In view of the trend of concurrent engineering, pondering simultaneously over these two problems in the development of assembly systems is significant for establishing a manufacturing system. This paper contemplates the assembly tool change and the assembly direction as measurements in ASP;and further, Equal Piles assembly line strategy is adopted and the imbalanced status of the system employed as criteria for the evaluation concerning ALB. Focus of the paper is principally on proposing hybrid evolutionary multiple-objective algorithms (HEMOAs) for solutions with regard to integrate the evolutionary multi-objective optimization and grouping genetic algorithms. The results provide a set of objectives and amend Pareto-optimal solutions to benefit decision makers in the assembly plan. In addition, an implemented decision analytic model supports the preference selection from the Pareto-optimal ones. Finally, the exemplifications demonstrate the effectiveness and performance of the proposed algorithm. The consequences definitely illustrate that HEMOAs search out Pareto-optimal solutions effectively and contribute to references for the flexible change of assembly system design.
The layout problem arises in a production plant during the study of a new production system, but also during a possible restructuring. The main aim of layout design is to reduce transportation and maintenance, which s...
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The layout problem arises in a production plant during the study of a new production system, but also during a possible restructuring. The main aim of layout design is to reduce transportation and maintenance, which simplifies management, shortens lead time, improves product quality and speeds up the response to market fluctuations. A principle of Group Technology (GT) advocates the division of a unity into small groups or cells. As it is most of the time impossible to design totally independent cells, the problem is to minimise traffic of items between the cells, for a fixed maximum cell size. This problem is known as cell formation problem (CFP). We propose here an original approach to solve this NP-hard problem. It is based on a groupinggenetic Algorithm (GGA), a special class of geneticalgorithms, heavily modified to suit the structure of grouping problems. The crucial advantage of this GGA is that it is able to deal with large instances of the problem thus becoming a powerful tool for an engineer determining a plant layout, allowing him or her to try several plant options, without the limitation of huge computation times. (C) 2000 IMACS/Elsevier Science B.V. All rights reserved.
The purpose of this paper is to describe the main problems concerning the design and operation of mixed-product assembly lines, We will focus on the design of assembly lines, which is most of the time composed in thre...
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The purpose of this paper is to describe the main problems concerning the design and operation of mixed-product assembly lines, We will focus on the design of assembly lines, which is most of the time composed in three steps. The first is the elaboration of the logical layout of the line, which Consists in the distribution of operations among workstations along the line. The second is the choice of the most efficient product mix and production sequence in relation to the operation phase. The third is the subsequent elaboration of the physical layout of the line, i.e., deciding about the disposition of the workstations, conveyor(s), possible buffers, etc., on the shop floor. In this paper, the accent will be put exclusively on the first two steps. The concept of balance for ordering (BFO) is introduced to solve these two interrelated problems. After an overview of the current work in this area, this paper presents in detail a very promising approach to solve the BFO: the grouping and ordering geneticalgorithms (geneticalgorithms heavily modified to solve grouping/ordering problems). In all cases, the main concern is the quality of the resulting line in terms of cost and its suitability to the line designer's needs (special user preferences are followed as closely as possible). Academic and experimental results are presented, and they confirm the efficiency of the proposed approaches. The work presented here will be integrated in a complete design of assembly lines software, called CISAL, Further work will take resource dimension and reliability, cost, and buffer dimensioning into account.
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