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Optimization methods for solving transportation problems on networks
Katja Prnaver, 2011, dissertation

Abstract: In this thesis we study problems from real situations, which can be applied to network graphs and solved using mathematical graph theory. We start with the problem of oriented network design. The problem originates from networks, where the flow over the arcs is important and many times limited with the capacity of the networks. There are several techniques and results on the problem of assigning the flow through the network channels. In our problem, we try to find the optimal network structure, which could be used in the design phase of the network. With metaheuristics, we search for optimal network structures for a given number of nodes. We define triangle neighborhood and compare the results of the algorithm with the conjecture by Choplin et al. [8]. Further, we study the problem of order picking and order batching in block structured warehouses. For order picking problem, we present the extension of a dynamic programming algorithm by Ratliff and Rosenthal [42], which enables the development of an algorithm for an unlimited number of blocks. In order to achieve this, a new presentation of states and transitions of dynamic programming algorithm is given. We prove that the resulting path is optimal for the given structure. We compare the optimal path lengths to the results found in literature and also investigate the impact of warehouse layout parameters onto the routing. Closely related to the problem of order picking, we investigate the order batching problem. We discuss the variation of the order batching problem with time windows and present the algorithmic approach to solving the problem. The previously presented optimal path algorithm is applied in the algorithm to ensure even better quality of results. We introduce the evaluation function of a batch and compare the results of the algorithm with the test data from the literature as well as with data from the real warehouse. We conclude by summarizing the results and stating some possible extensions and further work.
Keywords: graph theory, networks, optimization, shortest path problem, traveling salesman problem, algorithms, metaheuristics, order batching
Published: 03.06.2011; Views: 3822; Downloads: 149
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Hybridization of evolutionary algorithms
Iztok Fister, Marjan Mernik, Janez Brest, 2011, independent scientific component part or a chapter in a monograph

Keywords: hybridization, evolutionary algorithms, heuristic algorithms
Published: 01.06.2012; Views: 1158; Downloads: 56
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A general simplification algorithm
Boštjan Pivec, Vid Domiter, 2007, original scientific article

Abstract: In this article a new general algorithm for triangular mesh simplification is proposed. The algorithm extends Krivograd's work from 2D to 3D. For faster execution times a hash table is used. The main idea of the algorithm is based on vertex removal approach. With this approach we remove visually less important vertices. To determine their visual importance, all vertices have tobe evaluated. This way models still preserve their essential characteristics. With simplification we can also easily present and transfer models over the network.
Keywords: geometric modeling, triangular meshes, simplification, algorithms
Published: 31.05.2012; Views: 1024; Downloads: 20
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An efficient k'-means clustering algorithm
Krista Rizman Žalik, 2008, original scientific article

Abstract: This paper introduces k'-means algorithm that performs correct clustering without pre-assigning the exact number of clusters. This is achieved by minimizing a suggested cost-function. The cost-function extends the mean-square-error cost-function of k-means. The algorithm consists of two separate steps. The first is a pre-processing procedure that performs initial clustering and assigns at least one seed point to each cluster. During the second step, the seed-points are adjusted to minimize the cost-function. The algorithm automatically penalizes any possible winning chances for all rival seed-points in subsequent iterations. When the cost-function reaches a global minimum, the correct number of clusters is determined and the remaining seed points are located near the centres of actual clusters. The simulated experiments described in this paper confirm good performance of the proposed algorithm.
Keywords: algorithms, clustering analysis, k-means, cost-function, rival penalized mechanism, datasets
Published: 31.05.2012; Views: 1229; Downloads: 74
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Design of row-based flexible manufacturing system with evolutionary computation
Mirko Ficko, Jože Balič, 2008, published scientific conference contribution

Abstract: This paper discusses design of flexible manufacturing systems (FMSs) in one or multiple rows. Evolutionary computation, particularly genetic algorithms (GAs) proved to be successful in search of optimal solution for this type of problems. The model of solution, the most suitable way of coding the solutions into the organisms and the selected evolutionary and genetic operators are presented. In this connection, the most favourable number of rows and the sequence of devices in the individual row are established by means of genetic algorithms (GAs). In the end the test results of the application made and the analysis are discussed.
Keywords: flexible manufacturing system design, genetic algorithms, evolutionary computation, intelligent manufacturing systems, artificial intelligence
Published: 31.05.2012; Views: 1101; Downloads: 58
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A hexahedral mesh connectivity compression with vertex degrees
Sebastian Krivograd, Mladen Trlep, Borut Žalik, 2008, original scientific article

Abstract: This paper introduces a new algorithm for the compression of manifold hexahedral meshes topology, using vertex degree. The topology compression consists of two parts-the meshćs boundary consisting of quadrilaterals is compressed first, and then the hexahedra are processed by the help of six commands. The topology compression algorithm has been matched against the best-known method to-date, and shows itself to be competitive.
Keywords: hexahedral meshes topology, FEM, compression, topology compression algorithm, geometry, algorithms
Published: 31.05.2012; Views: 1017; Downloads: 61
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Embedding DSLS into GPLS
Dejan Hrnčič, Marjan Mernik, Barrett Richard Bryant, 2011, original scientific article

Abstract: Embedding of Domain-Specific Languages (DSLs) into General-Purpose Languages (GPLs) is oftenused to express domain-specific problems using the domainćs natural syntax inside GPL programs. It speeds up thedevelopment process, programs are more self-explanatory and repeating tasks are easier to handle. End-users ordomain experts know what the desired language syntax would look like, but do not know how to write a grammar andlanguage processing tools. Grammatical inference can be used for grammar extraction from input examples. Amemetic algorithm for grammatical inference, named MAGIc, was implemented to extract grammar from DSLexamples. In this work MAGIc is extended with embedding the inferred DSL into existing GPL grammar.Additionally, negative examples were also incorporated into the inference process. From the results it can be concludedthat MAGIc is successful for DSL embedding and that the inference process is improved with use of negativeexamples.
Keywords: memetic algorithms, doamin-specific languages, grammatical inference, embedding
Published: 01.06.2012; Views: 752; Downloads: 21
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