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Article
Publication date: 27 July 2018

Ivan Yatchev, Mehmet Sen, Iosko Balabozov and Ivan Kostov

The purpose of the paper is to clarify the influence of introducing magnetic concentrators on the performance of Hall effect based current sensors and to obtain dependencies of…

163

Abstract

Purpose

The purpose of the paper is to clarify the influence of introducing magnetic concentrators on the performance of Hall effect based current sensors and to obtain dependencies of the sensor characteristics on the conductor position.

Design/methodology/approach

The finite element method and Comsol software are used for analysis of the three-dimensional magnetic field of the constructions of Hall effect based current sensor with different types of magnetic concentrators – closed-core (of rectangular and toroidal type) and open-core of toroidal type – with additional larger air gap. The Hall plate is also included in the model with its real dimensions and the magnetic flux density is obtained by integrating over its volume.

Findings

It has been found that there is dependence of the output signal (proportional to the magnetic flux density) of Hall effect based current sensor with both closed- and open-core magnetic concentrators on the position of the current carrying conductor. Distribution of the magnetic flux density and dependencies of its value in the Hall plate on the conductor position and on the additional air gap have been obtained. Optimization is carried out with respect to the additional air gap and cross-section dimensions of the concentrator.

Originality/value

Estimation of the influence of the introducing magnetic concentrators is made with respect to relationships between the output signal and conductor position for different constructions of the magnetic core of the concentrators.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 37 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 4 May 2012

Ivan Yatchev, Marek Rudnicki, Krastyo Hinov and Vultchan Gueorgiev

The purpose of this paper is to solve the optimization problem for a permanent magnet linear actuator with moving magnet for driving a needle in a knitting machine. The…

195

Abstract

Purpose

The purpose of this paper is to solve the optimization problem for a permanent magnet linear actuator with moving magnet for driving a needle in a knitting machine. The optimization is carried out with respect to the maximal average force along the stroke.

Design/methodology/approach

The optimization factors are the dimensions of the permanent magnet and the pole length. For obtaining the objective function for each parameter combination, the static force‐stroke characteristic is computed. Three‐dimensional finite element analysis is employed for obtaining the electromagnetic force. The objective function is then approximated by secondary models on the basis of design of experiment. The optimization is carried out using sequential linear programming.

Findings

Optimal solution to the problem has been obtained and the force‐stroke characteristic of the optimal actuator is given.

Originality/value

The proposed approach employs sequential linear programming with move limits using trust region concept, 3D finite element analysis, design of experiments and secondary models for optimization of a permanent magnet linear actuator for individual needle driving in a knitting machine.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Available. Content available
Article
Publication date: 4 May 2012

Ivan Yatchev, Rumena Stancheva and Iliana Marinova

187

Abstract

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 3
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 11 September 2009

Vultchan Gueorgiev, Zaharinka Gergova and Ivan Yatchev

Differential sensor for linear displacement has been optimized in terms of linearity and sensitivity. The optimization of the sensor is carried out with respect to its…

267

Abstract

Purpose

Differential sensor for linear displacement has been optimized in terms of linearity and sensitivity. The optimization of the sensor is carried out with respect to its characteristic displacement‐output voltage.

Design/methodology/approach

Response surface methodology and design of experiments have been successfully applied for sensor optimization. First, a full factorial experiment – computation of the quasi‐static electromagnetic field of the sensor using the finite element method – has been performed. Secondary model has been created on the basis of finite element results. Then this model has been optimized with respect to two criteria – linearity and sensitivity.

Findings

The mutual influence of both criteria has been studied. In this way an optimal trade‐off between linearity and sensitivity of the sensor was achieved.

Research limitations/implications

Relatively small numbers of optimization criteria have been varied. The results can be further improved by adding additional factors to the study.

Originality/value

The results obtained improve characteristics of this type of sensor and make it low cost alternative to the high‐end linear displacement sensors in low to moderate accuracy applications.

Details

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

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Article
Publication date: 4 May 2012

Min Li and David Lowther

The inverse problem related to eddy current testing (ECT) is often formulated as a shape optimization problem. The purpose of this paper is to propose a methodology for…

329

Abstract

Purpose

The inverse problem related to eddy current testing (ECT) is often formulated as a shape optimization problem. The purpose of this paper is to propose a methodology for determining the optimal parameters of a sensor system for more accurate reconstruction of the crack shape.

Design/methodology/approach

In this paper, an objective function is formulated using the shape sensitivity information computed from the ECT data. The design of a non‐destructive testing (NDT) sensor is carried out through optimizing the sensor parameters under such a criterion.

Findings

The methodology proposed results in modifications to the original sensor geometry which makes it more sensitive to the depth changes in a crack. A square wave form of excitation is used in order to provide more information on the size of the crack at different depths, essentially through the superposition of a range of excitation frequencies, each of which has a different depth of penetration. The newly designed ECT sensor system is suitable for dealing with the natural crack problem.

Research limitations/implications

While the methodology is general and has been shown to work in a simulated environment, the result is not verified by the experiments because the newly designed device has not actually been fabricated.

Originality/value

This paper has demonstrated the possibility of designing a sensor probe using computer aided design tools without extensive physical testing. The design process is novel and based on a sensitivity approach. This is shown to be very efficient and effective and the solution of the inverse problem demonstrates a very fast convergence.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 4 May 2012

Iliana Marinova and Valentin Mateev

The purpose of this paper is to develop an inverse approach for 3D thermal sources determination.

326

Abstract

Purpose

The purpose of this paper is to develop an inverse approach for 3D thermal sources determination.

Design/methodology/approach

The developed approach is based on the Green's function for Poison's equation. Forward and inverse couple electromagnetic‐thermal field problems are formulated. Finite elements models are built and applied. Thermal field data are acquired by thermo vision camera. The thermal field sources are determined inside of the investigated inaccessible volume object using modeled and measured data with the developed approach.

Findings

The presented method and implemented examples demonstrate the possibilities of the developed approach for inverse source problem solution and determination of thermal field distributions of electrical devices.

Originality/value

The proposed inverse method uses the Green's function for Poison's equation for solution of thermal field problem taking into account the couple electromagnetic‐thermal problems. Proposed inverse method is very fast, accurate and can be used in many practical activities for electrical current determination and visualization in inaccessible regions only by measured external thermal field. Thermal field data needed for the method are easily acquired by thermo vision camera.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 4 May 2012

Kostadin Brandisky, Dominik Sankowski, Robert Banasiak and Ivaylo Dolapchiev

The purpose of this paper is to consider the optimization of an 8‐electrode cylindrical electrical capacitance tomography (ECT) sensor. The aim is to obtain maximum uniformity and…

264

Abstract

Purpose

The purpose of this paper is to consider the optimization of an 8‐electrode cylindrical electrical capacitance tomography (ECT) sensor. The aim is to obtain maximum uniformity and value of the sensitivity distribution of the sensor, while keeping the mutual capacitances between the electrodes above a predefined level.

Design/methodology/approach

The optimization methods that have been used are response surface methodology, genetic algorithm and a combination of both.

Findings

As results, optimum dimensions for the gap, mounting pipe, shield and insulation are determined, which ensure more uniform distribution of sensitivity in the sensing area.

Originality/value

The optimization strategies used – RSM and the combined RSM+GA – make the optimization of ECT sensors feasible. The results show the effectiveness of the RSM+GA strategy which could also be used for optimization of 3D multilayer ECT sensors.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 4 May 2012

Rumena Dimitrova Stancheva and Ilona Ilieva Iatcheva

The purpose of this paper is to evaluate the rate of discrepancy between the group of expected project results and the group of corresponding results realized preliminarily at the…

106

Abstract

Purpose

The purpose of this paper is to evaluate the rate of discrepancy between the group of expected project results and the group of corresponding results realized preliminarily at the design stage.

Design/methodology/approach

The authors formulate and solve the problem to determine the values of two assemblies of independent variables guaranteeing the project with the best (X→*) and as well this one with the worst (X→**) tolerance field of the expected Zx realization. The problem is formulated as an optimization one in nonlinear mathematical programming and it is solved by applying the flexible tolerance method.

Findings

By the use of basic relations in statistical science an expression of standard deviation σZx of Zx is found and proposed. The limits in which are expected to be change in the deviations between the main project results and the corresponding ones of the implemented design, mathematically defined previous to its realization.

Research limitations/implications

The accent is put on the cases when the device characteristics are presented as polynomials, obtained on the bases of the design of experiments (DOE) and the response surface methodology. An arbitrary technical characteristic Zx=Z(x→) is presented.

Practical implications

A researcher could confine numerically the tolerance field between project results and expected realized ones in the whole investigated region.

Originality/value

The paper is characterized by an original approach and a new expression of standard deviation is proposed which will be of interest to designers.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 4 May 2012

Paolo Di Barba and Antonio Savini

The purpose of this paper is to propose a method, reducing the order of the analysis problem, to help the solution of optimal shape design problems in electricity and magnetism.

126

Abstract

Purpose

The purpose of this paper is to propose a method, reducing the order of the analysis problem, to help the solution of optimal shape design problems in electricity and magnetism.

Design/methodology/approach

The proposed method, the background of which relies on the generalized Thévenin theorem, exploits a principle of field diakoptics.

Findings

After assessing the proposed method on a benchmark of inverse magnetostatics, the shape optimisation of the stress‐control ring in a power transformer is considered as the case study.

Originality/value

The proposed method makes it possible to reduce the cost of an optimisation procedure, when the direct problem is solved by means of finite‐element analysis.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 4 May 2012

Salvatore Coco, Antonino Laudani, Francesco Riganti Fulginei and Alessandro Salvini

The purpose of this paper is to apply a hybrid algorithm based on the combination of two heuristics inspired by artificial life to the solution of optimization problems.

161

Abstract

Purpose

The purpose of this paper is to apply a hybrid algorithm based on the combination of two heuristics inspired by artificial life to the solution of optimization problems.

Design/methodology/approach

The flock‐of‐starlings optimization (FSO) and the bacterial chemotaxis algorithm (BCA) were adapted to implement a hybrid and parallel algorithm: the FSO has been powerfully employed for exploring the whole space of solutions, whereas the BCA has been used to refine the FSO‐found solutions, thanks to its better performances in local search.

Findings

A good solution of the 8‐th parameters version of the TEAM problem 22 is obtained by using a maximum 200 FSO steps combined with 20 BCA steps. Tests on an analytical function are presented in order to compare FSO, PSO and FSO+BCA algorithms.

Practical implications

The development of an efficient method for the solution of optimization problems, exploiting the different characteristic of the two heuristic approaches.

Originality/value

The paper shows the combination and the interaction of stochastic methods having different exploration properties, which allows new algorithms able to produce effective solutions of multimodal optimization problems, with an acceptable computational cost, to be defined.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

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