Wyniki wyszukiwania - BazTech

1

Fast edge detection approach based on global optimization convex model and Split Bregman algorithm

Jing Y., Liu J., Liu Z., Cao H.

Diagnostyka

|

2018

|

Vol. 19, No. 2

23--29

EN

Active contour model is a typical and effective closed edge detection algorithm, which has been widely applied in remote sensing image processing. Since the variety of the image data source, the complexity of the application background and the limitations of edge detection, the robustness and universality of active contour model are greatly reduced in the practical application of edge extraction. This study presented a fast edge detection approach based on global optimization convex model and Split Bregman algorithm. Firstly, the proposed approach defined a generalized convex function variational model which incorporated the RSF model’s principle and Chan’s global optimization idea and could get the global optimal solution. Secondly, a fast numerical minimization scheme based on split Bregman iterative algorithm is employed for overcoming drawbacks of noise and others. Finally, the curve evolves to the target boundaries quickly and accurately. The approach was applied in real special sea ice SAR images and synthetic images with noise, fuzzy boundaries and intensity inhomogeneity, and the experiment results showed that the proposed approach had a better performance than the edge detection methods based on the GMAC model and RSF model. The validity and robustness of the proposed approach were also verified.

2

The island model as a Markov dynamic system

Schaefer R., Byrski A., Smołka M.

International Journal of Applied Mathematics and Computer Science

|

2012

|

Vol. 22, no. 4

971-984

EN

Parallel multi-deme genetic algorithms are especially advantageous because they allow reducing the time of computations and can perform a much broader search than single-population ones. However, their formal analysis does not seem to have been studied exhaustively enough. In this paper we propose a mathematical framework describing a wide class of island-like strategies as a stationary Markov chain. Our approach uses extensively the modeling principles introduced by Vose, Rudolph and their collaborators. An original and crucial feature of the framework we propose is the mechanism of inter-deme agent operation synchronization. It is important from both a practical and a theoretical point of view. We show that under a mild assumption the resulting Markov chain is ergodic and the sequence of the related sampling measures converges to some invariant measure. The asymptotic guarantee of success is also obtained as a simple issue of ergodicity. Moreover, if the cardinality of each island population grows to infinity, then the sequence of the limit invariant measures contains a weakly convergent subsequence. The formal description of the island model obtained for the case of solving a single-objective problem can also be extended to the multi-objective case.

3

Użyteczność deterministycznych metod optymalizacji globalnej do szacowania parametrów w zagadnieniach hydrologicznych

Grządziel M., Jełowicki J.

Woda-Środowisko-Obszary Wiejskie

|

2011

|

T. 11, z. 1

61-74

PL

Numeryczne metody optymalizacji, powszechnie stosowane w zagadnieniach hydrologicznych, nie gwarantują wyznaczenia minimum globalnego funkcji celu. Ich popularność wiąże się z tym, że mogą one być stosowane w zagadnieniach, w których liczba zmiennych decyzyjnych jest stosunkowo duża. W pracy dokonano przeglądu metod deterministycznych, które umożliwiają znalezienie optimum globalnego w przypadku, gdy funkcja celu ma więcej niż jedno minimum lokalne. Metody te mogą być podzielone na dwie kategorie: asymptotycznie kompletne oraz kompletne. Podczas gdy algorytmy należące do obu klas są w stanie generować ciąg rozwiązań przybliżonych zbieżny do rozwiązania zagadnienia optymalizacji globalnej, to tylko dla algorytmów należących do drugiej z wymienionych kategorii są dostępne nieheurystyczne kryteria stopu. Przykłady przedstawione w pracy ilustrują możliwości zastosowania metod asymptotycznie kompletnych do szacowania parametrów w modelach procesów hydrologicznych, takich jak: modele różniczkowe przepływu wód gruntowych, modele hydrauliczne wchodzące w skład modeli hydrodynamicznych wykorzystywanych do modelowania zasobów wód powierzchniowych, modele typu opad-odpływ czy też integralne modele zlewni.

EN

Most numerical optimization methods that are widely used in hydrology don't guarantee reaching the global minimum of the goal function. They became popular mainly due to their ability of handling relatively multi-dimensional problems. The paper reviews the deterministic methods capable of finding the global optimum in the presence of local optima. They can be divided into two categories: asymptotically complete methods and complete methods. While algorithms from both classes can generate a sequence converging to a solution of the global optimization problem, only for the algorithms from the latter class non-heuristic stopping criteria are available. The examples presented in the paper illustrate the applicability of asymptotically complete methods to parameter estimation in modelling hydrological processes, such as differential models of groundwater flow, hydraulic models embedded into hydrodynamic models of river systems, the precipitation–outflow models or integral catchment models.

4

Global minimum optimization using Diffusion Monte Carlo approach

Kazimirski J. K.

Studia i Materiały / Europejska Uczelnia Informatyczno-Ekonomiczna w Warszawie

|

2011

|

Nr 1(1)

63--71

EN

In this preliminary study we present a new approach for a global minimum search of a continuous objective function based on the Diffusion Monte Carlo (DMC) method. In this article we suggest the simple implementation of the computer algorithm. W also test the efficiency of the DMC based approach against a pure random approach based on blind search (random sampling) and random walk algorithms. We use four test problems, namely Ackley's and Griewangk's functions in 5 and 20 dimensions. We show that in all tested cases the DMC algorithm performs significantly better than pure random methods - the optimal solutions generated by DMC method are much closer to the known global minimum of the test problems than the results obtained with blind search and random walk algorithms.

PL

W artykule przedstawiona została metoda optymalizacji globalnej dowolnej funkcji ciągłej oparta o algorytm dyfuzyjnego Monte Carlo (DMC). Proponujemy sposób prostej implementacji zaproponowanego algorytmu, a także przedstawiamy wstępne rezultaty symulacji pokazujących efektywność metody DMC w porównaniu z metodami czysto losowymi - próbkowaniem losowym i błądzeniem losowym. Jako problemy testowe w symulacjach wykorzystujemy funkcję Ackley-a i Griewangk-a w wariantach 5- i 20-wymiarowym. Rezultaty przeprowadzonych symulacji wskazują na znacznie większą efektywność metody DMC w porównaniu z pozostałymi - uzyskane za jej pomocą rozwiązania są znacznie bliższe globalnemu minimum niż wyniki uzyskane metodami czysto losowymi.

5

Random perturbation of the projected variable metric method for nonsmooth nonconvex optimization problems with linear constraints

El Mouatasim A., Ellaia R., Souza de Cursi E.

International Journal of Applied Mathematics and Computer Science

|

2011

|

Vol. 21, no 2

317-329

EN

We present a random perturbation of the projected variable metric method for solving linearly constrained nonsmooth (i.e., nondifferentiable) nonconvex optimization problems, and we establish the convergence to a global minimum for a locally Lipschitz continuous objective function which may be nondifferentiable on a countable set of points. Numerical results show the effectiveness of the proposed approach.

6

A neural-network controlled dynamic evolutionary scheme for global molecular geometry optimization

Styrcz A., Mrozek J., Mazur G.

International Journal of Applied Mathematics and Computer Science

|

2011

|

Vol. 21, no 3

559-566

EN

A novel, neural network controlled, dynamic evolutionary algorithm is proposed for the purposes of molecular geometry optimization. The approach is tested for selected model molecules and some molecular systems of importance in biochemistry. The new algorithm is shown to compare favorably with the standard, statically parametrized memetic algorithm.

7

Simple 3D object reconstruction using global optimization

Okrasa A.I., Gwizdałła T.M.

Prace Naukowe Politechniki Warszawskiej. Elektronika

|

2009

|

z. 169

137-144

EN

In the paper we deal with the problem of three-dimensional shape reconstruction when its two-dimensional projections from selected directions are available. This situation corresponds e.g. to the trial of digitalizing the shape from photographs. We propose a methods for creating the mesh, projecting the shape keeping the information about light and perspective. On this basis we use SA technique to modify this shape in a controlled way in order to reproduce the initially assumed one best.

8

Comparison of Interval C/C++ Libraries in Global Optimization

Dąbrowski R., Kubica B.J.

Prace Naukowe Politechniki Warszawskiej. Elektronika

|

2009

|

z. 169

51-56

EN

This article contains results of examination and comparison of some most popular interval libraries. Comparative analysis was based on investigating the efficiency of computations of simple functions and efficiency of the Interval-Branch-And-Bound global optimization method.

9

Breakthrough in Interval Data Fitting II. From Ranges to Means and Standard Deviations

Gutowski M.W.

Prace Naukowe Politechniki Warszawskiej. Elektronika

|

2009

|

z. 169

73-78

EN

Interval analysis, when applied to the so called problem of experimental data fitting, appears to be still in its infancy. Sometimes, partly because of the unrivaled reliability of interval methods, we do not obtain any results at all. Worse yet, if this happens, then we are left in the state of complete ignorance concerning the unknown parameters of interest. This is in sharp contrast with widespread statistical methods of data analysis. In this paper I show the connections between those two approaches: how to process experimental data rigorously, using interval methods, and present the final results either as intervals (guaranteed, rigorous results) or in a more familiar probabilistic form: as a mean value and its standard deviation.

10

Breakthrough in Interval Data Fitting I. The Role of Hausdorff Distance

Gutowski M.W.

Prace Naukowe Politechniki Warszawskiej. Elektronika

|

2009

|

z. 169

63-72

EN

This is the first of two papers describing the process of fitting experimental data under interval uncertainty. Probably the most often encountered application of global optimization methods is finding the so called best fitted values of various parameters, as well as their uncertainties, based on experimental data. Here I present the methodology, designed from the very beginning as an interval-oriented tool, meant to replace to the large extent the famous Least Squares (LSQ) and other slightly less popular methods. Contrary to its classical counterparts, the presented method does not require any poorly justified prior assumptions, like smallness of experimental uncertainties or their normal (Gaussian) distribution. Using interval approach, we are able to fit rigorously and reliably not only the simple functional dependencies, with no extra effort when both variables are uncertain, but also the cases when the constitutive equation exists in implicit rather than explicit functional form. The magic word and a key to success of interval approach appears the Hausdorff distance.

11

Przegląd zastosowań algorytmów optymalizacji globalnej w przetwarzaniu danych sejsmicznych

Pieniążek K.

Nafta-Gaz

|

2009

|

R. 65, nr 12

942--946

PL

W artykule omówiono zaczerpnięte z literatury światowej przykłady aplikacji metod optymalizacji globalnych w przetwarzaniu danych sejsmicznych. Metody optymalizacyjne są pomocne zwłaszcza w zawansowanych procedurach przetwarzania – inwersji, czy analizie AVO. Techniki takie jak metoda symulowanego wyżarzania czy algorytmy genetyczne próbuje się stosować w rozwiązaniu problemów, które w dużym stopniu uwzględniają niejednorodność i złożoność budowy ziemi i dla których rozwiązanie analityczne jest trudne lub niemożliwe do otrzymania.

EN

In this paper the examples from literature of application algorithms of global optimization in seismic data processing are presented. Optimization methods are helpful especially in advanced processing procedures – inversion or AVO analysis. Technique such as simulated annealing or genetic algorithms are tried to be applied in solving the problems which take into account heterogeneity and complexity of the geological media and which can not be solved in a traditional way.

12

Global multicriteria optimization in weather routing

Szłapczyńska J.

Elektronika : konstrukcje, technologie, zastosowania

|

2009

|

Vol. 50, nr 11

27-30

EN

Route optimization for ships may be defined as a constrained multicriteria optimization problem. This paper presents an already implemented solution to the problem based on a multicriteria evolutionary algorithm (SPEA) and a ranking method (Fuzzy TOPSIS). Research results of the solution indicate the necessity of reduction of total execution time of the algorithm. Thus, in the paper applicable alternative optimization methods in weather routing are reviewed and the most suitable methods are appointed in the final conclusions.

PL

Proces optymalizacji tras statku zdefiniować można jako wielokryterialne zadanie optymalizacyjne z ograniczeniami. W artykule prezentowane jest, zaimplementowane wcześniej, narzędzie służące do rozwiązywania zadania optymalizacji tras. Wykorzystuje ono dwa mechanizmy optymalizacji wielokryterialnej: ewolucyjny algorytm SPEA oraz metodę rankingową Fuzzy TOPSIS. Uzyskane wyniki badań prezentowanego narzędzia wskazują na konieczność redukcji łącznego czasu wykonania algorytmu. Dlatego też w artykule przedstawiono przegląd alternatywnych metod optymalizacji wielokryterialnej, możliwych do zastosowania w badanym przypadku. Dodatkowo podjęto próbę wskazania rozwiązania najkorzystniejszego z punktu wiedzenia rozpatrywanego problemu.

13

Strength Pareto Evolutionary Approach to weather routing - preliminary results

Szłapczynska J, Śmierzchalski R.

Prace Naukowe Politechniki Warszawskiej. Elektronika

|

2008

|

z. 165

221-228

EN

This paper describes application of Strength Pareto Evolutionary Algorithm (SPEA) to an optimization problem in weather routing. The paper includes a description of SPEA algorithm and defines the constrained weather routing optimization problem. It also presents a proposal and preliminary test results of SPEA-based weather routing evolutionary algorithm.

14

Some new methods in the evolutionary search of atomic cluster shape

Stasikowski A., Gwizdałła T.

Prace Naukowe Politechniki Warszawskiej. Elektronika

|

2008

|

z. 165

213-220

EN

The problem of atomic structure optimization related to the minimization of its total energy is a fundamental physical problem as well as hard computational task. For the few last years we have presented some observations concerning the advantages and drawbacks of EA used as a tool to solve such questions. In this paper we would like to present some new approaches devoted to improve the general, not problem oriented part of algorithm. The results obtained for two techniques: population migration and Opposition-Based Learning show that the specific operators, designed for the given problem are still the most important part of algorithm.

15

Simulation-based optimization - myths and reality

Miazga P.

Prace Naukowe Politechniki Warszawskiej. Elektronika

|

2008

|

z. 165

131-137

EN

The present paper discusses the influence of simulation model accuracy on the convergence of electromagnetic structure simulation-based optimization. Neither response surface approximation method nor the algorithm of moving window filtering, commonly used for simulation error compensation, is not fully capable of guaranteeing proper convergence. The non-expensive device model with coarse meshing and a modified error compensation method can yield satisfactory results in a reasonable time.

16

Modeling fuzzy intervals with constraint logic programming

Kobylański P.

Prace Naukowe Politechniki Warszawskiej. Elektronika

|

2008

|

z. 165

9-22

EN

In this paper the method of modeling fuzzy intervals in fuzzy decision-making is presented. Described method makes use of constraint logic programming and it is based on the concept of descriptors. This approach is very general and it is consistent with Zadeh's extension principle and Bellman-Zadeh concept of fuzzy decision making. It fulfills Klir's requisite constraint and deals effectively with a drowning effect too. The idea of descriptors of fuzzy intervals and fuzzy constraints is illustrated with computational example of flexible scheduling problem in which robust for drowning effect schedule is found.

17

Integrated software platform for parallel global optimization

Niewiadomska-Szynkiewicz E., Zawadzka A.

Prace Naukowe Politechniki Warszawskiej. Elektronika

|

2008

|

z. 165

147-155

EN

The paper is concerned with global optimization techniques and their parallel implementation. We describe an integrated software platform GOOL-PV (Global Optimization Object-oriented Library-Parallel Version) that provides the tools for solving complex optimization problems on parallel and multi-core computers or computer clusters. Finally, we present the comparative study of sequential and parallel global optimization algorithms based on numerical results for a standard set of multimodal functions.

18

Exploring the search space with intervals

Gutowski M.

Prace Naukowe Politechniki Warszawskiej. Elektronika

|

2008

|

z. 165

77-84

EN

The term global optimization is used in several contexts. Most often we are interested in finding such a point (or points) in many-dimensional search space at which the objective function's value is optimal, i.e. maximal or minimal. Sometimes, however, we are also interested in stability of the solution, that is in its robustness against small perturbations. Here I present the original, interval-analysis-based family of methods designed for exhaustive exploration of the search space. The power of interval methods makes it possible to reach all mentioned goals within a single, unified framework.

19

Evolutionary approach to solve hub-and-spoke problem using α-cliques

Mażbic-Kulma B., Potrzebowski H., Stańczak J., Sęp K.

Prace Naukowe Politechniki Warszawskiej. Elektronika

|

2008

|

z. 165

121-130

EN

The theory of transportation systems deals with models of phenomena connected with movement of goods and persons. The model of the transportation system should simulate a real system, but should also be a tool that enables to solve given transportation tasks. In order to describe transportation system (rail, bus or air), as a routine a connection graph would be used. Vertices of the graph can be train stations, bus stops or in case of air transport - airports. The edges of the graph show direct connections between vertices. It can be noticed that such a graph can have many vertices as well as many edges. Its direct application can be difficult and computational problems can occur while one would try to organize or optimize such a transportation system. Therefore, a method of aggregation of such a graph was introduced, using the hub-and-spoke structured graph of connections. This structure enables to concentrate and order the transport of goods/persons among vertices. To obtain the hub-and-spoke structure an evolutionary algorithm (EA) was applied. EA divides the connection graph into α-cliques (a generalization of the notion of a clique, which groups into sub-graphs highly connected vertices) and then in each α-clique a vertex with a maximum degree in this sub-graph and a maximal number of connections among other selected hubs is chosen. The α-clique with chosen vertex constitutes a "hub" with point-to-point connections - "spokes". This method enables reducing the number of analyzed vertices as well as arcs of the graph. Examples visualizing functioning of the described algorithms are presented later in this paper.

20

Clonal selection algorithm with binary representation of solutions for non-stationary optimization tasks

Trojanowski K., Matusik G.

Prace Naukowe Politechniki Warszawskiej. Elektronika

|

2008

|

z. 165

229-236

EN

Non-stationary optimization with the immune based algorithms is studied in this paper. The algorithm works with a binary representation of solutions. A set of different types of binary mutation is proposed and experimentally verified. The mutations differ in the way of calculation of the number of bits to be mutated. Obtained results allow to indicate the leading formulas of calculation.