Wyniki wyszukiwania - BazTech

1

Tackling Permutation-based Optimization Problems with an Algebraic Particle Swarm Optimization Algorithm

Santucci Valentino, Baioletti Marco, Milani Alfredo

Fundamenta Informaticae

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2019

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Vol. 167, nr 1-2

133--158

EN

Particle Swarm Optimization (PSO), though originally introduced for continuous search spaces, has been increasingly applied to combinatorial optimization problems. In this paper, we focus on the PSO applications to permutation-based problems. As far as we know, the most popular and general PSO schemes for permutation solutions are those based on random key techniques. After highlighting the main criticalities of the random key approach, we introduce a discrete PSO variant for permutation-based optimization problems. By simulating search moves through a vector space, the proposed algorithm, Algebraic PSO (APSO), allows the original PSO design to be applied to the permutation search space. APSO directly represents both particle positions and velocities as permutations. The APSO search scheme is based on a general algebraic framework for combinatorial optimization based on strong mathematical foundations. However, in order to make this new scheme viable, some challenges have to be overcome: the choice of the order of the velocity terms, and the rationale behind the PSO inertial move. Design solutions have been proposed for both the issues. Furthermore, an alternative geometric interpretation of classical PSO dynamics allows to introduce a major APSO variant based on a novel concept of convex combination between permutation objects. In total, four APSO schemes have been introduced. Experiments have been held to compare the performances of the APSO schemes with respect to the random key based PSO schemes in literature. Widely adopted benchmark instances of four popular permutation problems have been considered. The experimental results clearly show that, with high statistical evidence, APSO outperforms its competitors and it reaches results comparable with state-of-the-art on most of the instances considered.

2

A comparison of nature inspired algorithms for the quadratic assignment problem

Chmiel W., Kadłuczka P., Kwiecień J., Filipowicz B.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2017

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Vol. 65, nr 4

513--522

EN

This paper presents an application of the ant algorithm and bees algorithm in optimization of QAP problem as an example of NP-hard optimization problem. The experiments with two types of algorithms: the bees algorithm and the ant algorithm were performed for the test instances of the quadratic assignment problem from QAPLIB, designed by Burkard, Karisch and Rendl. On the basis of the experiments results, an influence of particular elements of algorithms, including neighbourhood size and neighbourhood search method, will be determined.

3

Zastosowanie algorytmów rojowych w rozwiązywaniu zagadnień permutacyjnych

Chmiel W., Kadłuczka P., Packanik G.

Automatyka / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2011

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T. 15, z. 2

117-126

PL

W artykule przedstawiono wyniki badań nad zastosowaniem algorytmów rojowych w optymalizacji zagadnienia szeregowania zadań, jako przykładu AP-trudnego zagadnienia optymalizacyjnego. W oparciu o instancje testowe dla zagadnienia szeregowania zadań zaproponowane przez E. Taillarda, przeprowadzono eksperymenty obliczeniowe, porównując wyniki otrzymywane przez algorytm ptasi oraz algorytm pszczeli. Przebadano także wpływ implementacji poszczególnych elementów algorytmów, takich jak liczba, dokładność i sposób przeszukiwania otoczenia rozwiązań obiecujących, na uzyskiwane wyniki optymalizacji. Pozwoliło to na sformowanie ogólnych wniosków dotyczących własności obu algorytmów.

EN

The objective of this paper is to examine the most important properties of a multi-population genetic algorithm. These elements include: connection topology, migration size, migration interval and a method for migrant selection. A short review of the existing papers on multi-population algorithms is presented. A new diversity measure that applies to permutation encoding is introduced. The proposed measure has proved effective in helping to retain balance between population diversity and convergence. A multi-population genetic algorithm, with different parameters like type of topology, migration interval, migration size and selection method was tested against several different test instances of traveling salesman problem, that belongs to the NP-hard permutational problem class.

4

Efektywność wielopopulacyjnego algorytmu ewolucyjnego dla zagadnień permutacyjnych

Filipowicz B., Chmiel W., Dudek M., Kadłuczka P.

Automatyka / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2011

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T. 15, z. 2

147-158

PL

W artykule przedstawiono wyniki badań najistotniejszych elementów wielopopulacyjnego algorytmu ewolucyjnego. W zastosowanym modelu wyspowym należą do nich: topologia połączeń, rozmiar i częstotliwość migracji oraz metoda selekcji migrantów. Zaproponowana miara różnorodności populacji może być wykorzystywana dla szerokiej klasy zagadnień permutacyjnych, których przykładem jest rozważane zagadnienie komiwojażera (TSP). Badania eksperymentalne przeprowadzono dla standardowych zagadnień testowych zaczerpniętych z biblioteki TSPLib95.

EN

The objective of this study is to examine the most important traits of a multi-population genetic algorithm. These elements include: connection topology, migration size, migration interval and migrant seleetion method. A review of the existing papers on multi-population algorithms is presented. A new diversity measure that applies to permutation encoding is introduced. It has proved effective in helping to retain balance between population diversity and convergence. For each trait, several algorithm configurations have been tested. Every configuration was tested against 25 different test instances, which were derived from the TSPLib95 library. Test results showed that, among the tested parameters, the most important was topology. Of the eleven topologies, a circular (ring) topology consisting of 16 islands obtained the best results. Varying of migration interval showed little correlation with the solution quality, but it did affect the convergence time. In comparison to other parameters, migration size exerts a relatively strong influence on performance. Moreover, a medium migration size proved to be reasonable. Among migrant selection methods, random selection outperformed these methods that exert selective pressure.

5

An Improved Method of Permutation Correction in Convolutive Blind Source Separation

Wang L., Ding H., Yin F.

Archives of Acoustics

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2010

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Vol. 35, No. 4

493-504

EN

This paper proposes an improved method of solving the permutation problem inherent in frequency-domain of convolutive blind source separation (BSS). It combines a novel inter-frequency dependence measure: the power ratio of separated signals, and a simple but effective bin-wise permutation alignment scheme. The proposed method is easy to implement and surpasses the conventional ones. Simulations have shown that it can provide an almost ideal solution of the permutation problem for a case where two or three sources were mixed in a room with a reverberation time of 130 ms.