Wyniki wyszukiwania - BazTech

1

Invasive weed optimization algorithm applied for solving the inverse Stefan problem

Hetmaniok E.

Hutnik, Wiadomości Hutnicze

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2014

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Vol. 81, nr 1

76--79

EN

Goal of the paper is to present and comment the results of applying the Invasive Weed Optimization (IWO) Algorithm for solving the two-phase inverse Stefan problem. Idea of the IWO algorithm is based on the dynamic growth and reproduction of the weeds colony which makes it a part of the artificial intelligence algorithms inspired by the behaviors from real world. Inverse Stefan problem is the ill-posed boundary value problem describing thermal processes with the change of phase and it consists in reconstruction of some missing elements by using some additional information.

PL

Celem pracy jest przedstawienie procedury służącej do rozwiązania dwufazowego odwrotnego zagadnienia Stefana przy użyciu algorytmu inwazji chwastów IWO (Invasive Weed Optimization algorithm), naśladującego zachowanie populacji chwastów. Rozważane zadanie polegać będzie na odtworzeniu współczynnika wnikania ciepła tak, aby funkcje opisujące położenie granicy rozdziału faz oraz rozkłady temperatury spełniały model matematyczny zadania. Jedna z zasadniczych części procedury polegać będzie na minimalizacji odpowiednio skonstruowanego funkcjonału za pomocą algorytmu IWO.

2

Reconstruction of the heat transfer coefficient on the grounds of experimental data

Słota D.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 34, nr 1

63-70

EN

Purpose: Solidification of pure metal can be modelled by a two-phase Stefan problem, in which the distribution of temperature in the solid and liquid phases is described by the heat conduction equation with initial and boundary conditions. The inverse Stefan problem can be applied to solve design problems in casting process. Design/methodology/approach: In numerical calculations the alternating phase truncation method, the Tikhonov regularization and the genetic algorithm were used. The featured examples of calculations show a very good approximation of the experimental data. Findings: The verification of the method of reconstructing the cooling conditions during the solidification of pure metals. The solution of the problem consists of selecting the heat transfer coefficient on the boundary, so that the temperature in selected points on the boundary of the domain assumes given values. Research limitations/implications: The method requires that it must be possible to describe the sought boundary condition by means of a finite number of parameters. It is not necessary, that the sought boundary condition should be linearly dependent on those parameters. Practical implications: The presented method can be easy applied to solve design problems of different types, e.g. for the design of continuous casting installations (incl. the selection of the length of secondary cooling zones, the number of jets installed in individual zones, etc.). Originality/value: Verification, on the grounds of experimental data, the formerly devised method of determining the heat transfer coefficient during the solidification of pure metals.

3

Calculation of the cooling condition in the phase change problem

Słota D.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 33, nr 1

70-77

EN

Purpose: The purpose of the paper is to present the method of calculation of the cooling condition in the phase change problem. The considered problem consists of the reconstruction of a function describing the heat transfer coefficient, when the temperature values in selected points of the solid phase are known. Design/methodology/approach: In numerical calculations, the Tikhonov regularization, the genetic algorithm and the alternating phase truncation method were used. Findings: The featured examples of calculations show a very good approximation of the exact solution and stability of the procedure. Practical implications: The paper presents an example of selection of the heat transfer coefficient given in the form of a continuous function. This method can be easily adopted also for the determination of other parameters of the problem discussed here. Originality/value: The calculations made, only part of which has been presented in this paper, show stability of the method proposed, both in terms of the input data errors and the number of control points, thus corroborating usefulness of the presented approach.

4

Modelling of the optimum cooling condition in two-dimensional solidification processes

Słota D.

Archives of Computational Materials Science and Surface Engineering

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2009

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Vol. 1, nr 1

45-52

EN

Purpose: This paper presents the method of the calculation of the cooling condition in the two-dimensional solidification processes. Design/methodology/approach: The considered problem consists in the reconstruction of the function that describes the heat transfer coefficient on the boundary, when the temperature measurements in selected points of the solid phase are well-known. In calculations the alternating phase truncation method, the genetic algorithm and the Tikhonov regularization were used. Findings: The calculations show a very good approximation of the exact solution and the stability of the procedure. Research limitations/implications: On the bases of the results that every start-up of the genetic algorithm leads to similar results, which are reflected by very low values of the standard deviation. Originality/value: The calculations point to the stability of the proposed method in view of the input data errors, number of control points, substantiating the usability of such approach.

5

Determination of the boundary conditions in two-dimensional solidification of pure metals

Słota D.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 28, nr 1

59-62

EN

Purpose: Solidification of pure metal can be modelled by a two-phase Stefan problem, in which the distribution of temperature in solid and liquid phases is described by a heat conduction equation with initial and boundary conditions. The inverse Stefan problem can be applied to solve design problems in continuous casting process. Design/methodology/approach: In numerical calculations the alternating phase truncation method, the Tikhonov regularization and the genetic algorithm were used. The featured examples of calculations show a very good approximation of the exact solution and the stability of the procedure. Findings: The paper presents the determination method of cooling conditions in two-dimensional solidification of pure metals. The solution of the problem consisted of selecting a heat transfer coefficient on boundary, so that the temperature in selected points of the boundary of the domain would assumed the given values. Research limitations/implications: The method requires that it must be possible to describe the sought boundary condition by means of a finite number of parameters. It is not necessary, however, that the sought boundary condition should be linearly dependent on those parameters. Practical implications: The presented method can be applied without any problem to solve design problems of different types, e. g. for the design of continuous casting installations (incl. the selection of the length of secondary cooling zones, the number of jets installed in individual zones, etc.). Originality/value: The paper presents the new method of selection of the heat transfer coefficient in two-dimensional inverse Stefan problem, so that the temperature in selected points of the boundary of the domain would assumed the given values.