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Article
Publication date: 1 April 1986

S. GRATKOWSKI

Infinite elements are becoming increasingly popular as an efficient and economical means of extending the finite element method to deal with unbounded domains. In this…

Abstract

Infinite elements are becoming increasingly popular as an efficient and economical means of extending the finite element method to deal with unbounded domains. In this paper an infinite element is considered which has three nodes and is compatible with conventional quadratic triangles and quadratic quadrilaterals. The closed‐form expressions for the element matrix are obtained.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 5 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 January 1994

Stanislaw Gratkowski

This paper presents ‘infinite’ finite elements for magnetic field problems with open boundaries in r‐z and r‐φ geometries. The formulations of the elements are so simple…

Abstract

This paper presents ‘infinite’ finite elements for magnetic field problems with open boundaries in r‐z and r‐φ geometries. The formulations of the elements are so simple that closed‐form expressions for the element matrix are obtained. In order to test the new elements, simple examples, for which analytical solutions exist, are analysed.

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COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 13 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 January 1994

Stanislaw Gratkowski and Marek Ziółkowski

This paper describes numerical tests for a three dimensional infinite element suitable for finite element modelling of open boundary field problems. The infinite element…

Abstract

This paper describes numerical tests for a three dimensional infinite element suitable for finite element modelling of open boundary field problems. The infinite element has four nodes and is compatible with conventional cuboids. The effectiveness of the infinite element in the interior — finite element region is shown by comparing the accuracy and the CPU time when various boundary conditions are applied. The possibility of computing the external fields is also illustrated.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 13 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 April 1995

S. Gratkowski, L. Pichon and A. Razek

A basic difficulty encountered in applying the finite element method to unbounded wave problems is that the domain in which the field is to be computed is unbounded, while…

Abstract

A basic difficulty encountered in applying the finite element method to unbounded wave problems is that the domain in which the field is to be computed is unbounded, while finite element models are of finite size. There are several ways to overcome this difficulty. The widely used method is to truncate the finite element model at a finite position and apply suitable boundary conditions there. The relevant boundary conditions must absorb the outgoing wave and have been called absorbing boundary conditions (ABC's).

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 14 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 2 March 2015

Marcin Ziolkowski and Stanislaw Gratkowski

In many different engineering fields often there is a need to protect regions from electromagnetic interference. According to static and low-frequency magnetic fields the…

Abstract

Purpose

In many different engineering fields often there is a need to protect regions from electromagnetic interference. According to static and low-frequency magnetic fields the common strategy bases on using a shield made of conductive or ferromagnetic material. Another screening technique uses solenoids that generate an opposite magnetic field to the external one. The purpose of this paper is to discuss the shielding effect for a magnetic and conducting cylindrical screen rotating in an external static magnetic field.

Design/methodology/approach

The magnetic flux density is expressed in terms of the magnetic vector potential. Applying the separation of variables method analytical solutions are obtained for an infinitely long magnetic conducting cylindrical screen rotating in a uniform static transverse magnetic field.

Findings

Analytical formulas of the shielding factor for a cylindrical screen of arbitrary conductivity and magnetic permeability are given. A magnetic Reynolds number is found to be an appropriate indication of the change in magnetic field inside the screen. Useful simplified expressions are presented.

Originality/value

This paper treats in a qualitative way the possibility of static magnetic field shielding by using rotating conducting magnetic cylindrical screens. Analytical solutions are given. If the angular velocity is equal to zero or the relative permeability of the shield is equal to one the shielding factor has forms well known from literature.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 2
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 January 1992

K. Gawrylczyk, M. Gramz, S. Gratkowski, R. Sikora and M. Zidlkowski

This paper presents the practical configuration for detecting cracks in material, by applying an electromagnetic field along the largest dimension of the crack. An…

Abstract

This paper presents the practical configuration for detecting cracks in material, by applying an electromagnetic field along the largest dimension of the crack. An electromagnetic field formulation is proposed using Helmholtz's equation and Biot‐ Savart's law. The system equation is solved by using the finite element method (FEM). The exemplary results of calculation ‐ eddy currents lines in material and relative resistance versus probe position are presented.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 11 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 12 July 2011

Marcin Ziolkowski and Stanislaw Gratkowski

The purpose of this paper is to present the methodology of designing an exciter for Magnetic Induction Tomography (MIT). The design of the exciter must satisfy the…

Abstract

Purpose

The purpose of this paper is to present the methodology of designing an exciter for Magnetic Induction Tomography (MIT). The design of the exciter must satisfy the following requirements: maximize MIT system sensitivity and minimize harmful influence on electronic MIT equipment.

Design/methodology/approach

Two objective functions are considered, namely: a magnetic flux density in the protected regions and a module of the eddy‐current density vector in the object under test in the vicinity of a sensor. The paper shows a multi‐objective optimization technique (based on the weighted sum method) which, by coupling the finite‐element method with a genetic algorithm, supports the design of the exciter.

Findings

It is possible to design in a relatively simple way an exciter for MIT under the given assumptions.

Originality/value

Detailed description of the multi‐objective optimization procedure has been presented.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 30 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 11 September 2009

Marcin Ziolkowski and Stanislaw Gratkowski

The purpose of this paper is to present the methodology of designing an exciter for magnetic induction tomography (MIT). The design of the exciter must satisfy following…

Abstract

Purpose

The purpose of this paper is to present the methodology of designing an exciter for magnetic induction tomography (MIT). The design of the exciter must satisfy following requirements: maximize MIT system sensitivity and minimize harmful influence on electronic MIT equipment.

Design/methodology/approach

Two objective functions are considered, namely: a magnetic flux density in the protected regions and a module of the eddy current density vector in the object under test in the vicinity of a sensor. The paper demonstrates a multi‐objective optimization technique (based on the ε‐constrained method) which, by coupling the finite‐element method with a genetic algorithm (GA), supports the design of the exciter.

Findings

It is possible to design in a relatively simple way an exciter for MIT under the given assumptions.

Originality/value

The paper is of value in presenting a detailed description of the multi‐objective optimization procedure.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 28 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 4 July 2016

Barbara Szymanik and Miroslaw Woloszyn

– The purpose of this paper is to present two methods of detection for landmines with minimal metal content.

Abstract

Purpose

The purpose of this paper is to present two methods of detection for landmines with minimal metal content.

Design/methodology/approach

First, two methods of landmine detection are presented: magnetic and infrared with microwave heating. For each method the numerical algorithm of an object’s position and properties determination are presented. Furthermore, the experimental results of several landmines detection using both methods are presented.

Findings

It is possible to detect the landmines with minimal metal content using both magnetic and infrared methods. It is also possible to determine the detected objects’ exact position and properties using developed numerical algorithms.

Originality/value

The idea of using the magnetic method to detect the plastic landmines is, to the best knowledge of the authors, new. For both methods, the numerical algorithms of objects’ parameters determination are original.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 35 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 9 October 2009

Ryszard Palka, Stanislaw Gratkowski, Krzysztof Stawicki and Piotr Baniukiewicz

The purpose of this paper is to develop a magnetic induction tomography (MIT) system as well as the conductivity reconstruction algorithms (inverse problem).

Abstract

Purpose

The purpose of this paper is to develop a magnetic induction tomography (MIT) system as well as the conductivity reconstruction algorithms (inverse problem).

Design/methodology/approach

In order to define and verify the solution of the inverse problem, the forward problem is formulated using mathematical model of the system. The forward problem is solved using the finite element method. The optimization of the excitation unit is based on the numerical solutions of the direct problem. All the dimensions and shape of the excitation system are optimized in order to focus the main part of the magnetic field in the vicinity of the receiver. Finally, two formulations of the inverse problem are discussed: based on the inversion of the Biot‐Savart law; and based on the artificial neural networks.

Findings

The formulation of the forward problem of the considered MIT system is given. The construction of the exciter unit that focuses the main part of the magnetic field in the vicinity of the receiver is proposed. Two formulations of the inverse problem are discussed. First using the inversion of the Biot‐Savart law and second using the artificial neural network. The neural networks seem to be promising tools for reconstructing the MIT images.

Originality/value

This paper demonstrates a real‐life MIT system whose performance is satisfactorily predicted by mathematical models. The original design of the exciter is shown. The new approach to the inverse problem in MIT – the use of the artificial neural network – is presented.

Details

Engineering Computations, vol. 26 no. 7
Type: Research Article
ISSN: 0264-4401

Keywords

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