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Article
Publication date: 21 December 2021

Vahid Badeli, Sascha Ranftl, Gian Marco Melito, Alice Reinbacher-Köstinger, Wolfgang Von Der Linden, Katrin Ellermann and Oszkar Biro

This paper aims to introduce a non-invasive and convenient method to detect a life-threatening disease called aortic dissection. A Bayesian inference based on enhanced…

809

Abstract

Purpose

This paper aims to introduce a non-invasive and convenient method to detect a life-threatening disease called aortic dissection. A Bayesian inference based on enhanced multi-sensors impedance cardiography (ICG) method has been applied to classify signals from healthy and sick patients.

Design/methodology/approach

A 3D numerical model consisting of simplified organ geometries is used to simulate the electrical impedance changes in the ICG-relevant domain of the human torso. The Bayesian probability theory is used for detecting an aortic dissection, which provides information about the probabilities for both cases, a dissected and a healthy aorta. Thus, the reliability and the uncertainty of the disease identification are found by this method and may indicate further diagnostic clarification.

Findings

The Bayesian classification shows that the enhanced multi-sensors ICG is more reliable in detecting aortic dissection than conventional ICG. Bayesian probability theory allows a rigorous quantification of all uncertainties to draw reliable conclusions for the medical treatment of aortic dissection.

Originality/value

This paper presents a non-invasive and reliable method based on a numerical simulation that could be beneficial for the medical management of aortic dissection patients. With this method, clinicians would be able to monitor the patient’s status and make better decisions in the treatment procedure of each patient.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 41 no. 3
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 September 2003

U. Baumgartner, M. Grumer, M. Jaindl, A. Köstinger, Ch. Magele, K. Preis, M. Reinbacher and S. Voller

Nowadays, there are strong movements towards development and usage of multimedia courseware as a means of knowledge transfer. Many authors of textbooks or lecture notes are now…

456

Abstract

Nowadays, there are strong movements towards development and usage of multimedia courseware as a means of knowledge transfer. Many authors of textbooks or lecture notes are now striving to redesign the supporting material for their major courses in a structured, highly efficient way, including interactive content and media. Thus, in order to avoid unnecessary work load resulting from updating and publishing various courseware versions, tools for improving document creation and conversion have been developed and are now being applied for the first time on a new “Electrodynamics”‐‐ courseware.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 22 no. 3
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 29 April 2014

Ramzi Ben Ayed and Stéphane Brisset

– The aim of this paper is to reduce the evaluations number of the fine model within the output space mapping (OSM) technique in order to reduce their computing time.

60

Abstract

Purpose

The aim of this paper is to reduce the evaluations number of the fine model within the output space mapping (OSM) technique in order to reduce their computing time.

Design/methodology/approach

In this paper, n-level OSM is proposed and expected to be even faster than the conventional OSM. The proposed algorithm takes advantages of the availability of n models of the device to optimize, each of them representing an optimal trade-off between the model error and its computation time. Models with intermediate characteristics between the coarse and fine models are inserted within the proposed algorithm to reduce the number of evaluations of the consuming time model and then the computing time. The advantages of the algorithm are highlighted on the optimization problem of superconducting magnetic energy storage (SMES).

Findings

A major computing time gain equals to three is achieved using the n-level OSM algorithm instead of the conventional OSM technique on the optimization problem of SMES.

Originality/value

The originality of this paper is to investigate several models with different granularities within OSM algorithm in order to reduce its computing time without decreasing the performance of the conventional strategy.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 7 September 2015

Stephan Klomberg, Ernst Farnleitner, Gebhard Kastner and Oszkár Bíró

The purpose of this paper is to carry out an analytical approximation model (heat transfer model (HTM)) for the calculation of the heat transfer coefficient at the end winding…

103

Abstract

Purpose

The purpose of this paper is to carry out an analytical approximation model (heat transfer model (HTM)) for the calculation of the heat transfer coefficient at the end winding bars of large hydro generators. These coefficients are needed for lumped parameter thermal models in the design process.

Design/methodology/approach

The computational fluid dynamics simulation in combination with conjugate heat transfer (CHT) validates the accuracy of the HTM. The theoretical approach describes the formulation of the heat transfer coefficient and the Gauss-Newton method has been applied to find the coefficients of the approximation model.

Findings

The paper describes the new analytical approximation model for the heat transfer coefficient at the end winding bars of hydro generators and shows also the validation to simulation results.

Originality/value

The analytical approximation model for the heat transfer coefficient at the end winding bars has been described and a comparison with CHT results has shown a good agreement.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 1 January 2014

Ziyan Ren, Dianhai Zhang and Chang Seop Koh

The purpose of this paper is to propose a multi-objective optimization algorithm, which can improve both the performance robustness and the constraint feasibility when the…

165

Abstract

Purpose

The purpose of this paper is to propose a multi-objective optimization algorithm, which can improve both the performance robustness and the constraint feasibility when the uncertainty in design variables is considered.

Design/methodology/approach

Multi-objective robust optimization by gradient index combined with the reliability-based design optimization (RBDO).

Findings

It is shown that searching for the optimal design of the TEAM problem 22, which can minimize the magnetic stray field by keeping the target system energy (180 MJ) and improve the feasibility of superconductivity constraint (quenching condition), is possible by using the proposed method.

Originality/value

RBDO method applied to the electromagnetic problem cooperated with the design sensitivity analysis by the finite element method.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 1/2
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 11 August 2023

Mohammad Mushfiqur Rahman, Arbaaz Khan, David Lowther and Dennis Giannacopoulos

The purpose of this paper is to develop surrogate models, using deep learning (DL), that can facilitate the application of EM analysis software. In the current status quo…

205

Abstract

Purpose

The purpose of this paper is to develop surrogate models, using deep learning (DL), that can facilitate the application of EM analysis software. In the current status quo, electrical systems can be found in an ever-increasing range of products that are part of everyone’s daily live. With the advances in technology, industries such as the automotive, communications and medical devices have been disrupted with new electrical and electronic systems. The innovation and development of such systems with increasing complexity over time has been supported by the increased use of electromagnetic (EM) analysis software. Such software enables engineers to virtually design, analyze and optimize EM systems without the need for building physical prototypes, thus helping to shorten the development cycles and consequently cut costs.

Design/methodology/approach

The industry standard for simulating EM problems is using either the finite difference method or the finite element method (FEM). Optimization of the design process using such methods requires significant computational resources and time. With the emergence of artificial intelligence, along with specialized tools for automatic differentiation, the use of DL has become computationally much more efficient and cheaper. These advances in machine learning have ushered in a new era in EM simulations where engineers can compute results much faster while maintaining a certain level of accuracy.

Findings

This paper proposed two different models that can compute the magnetic field distribution in EM systems. The first model is based on a recurrent neural network, which is trained through a data-driven supervised learning method. The second model is an extension to the first with the incorporation of additional physics-based information to the authors’ model. Such a DL model, which is constrained by the laws of physics, is known as a physics-informed neural network. The solutions when compared with the ground truth, computed using FEM, show promising accuracy for the authors’ DL models while reducing the computation time and resources required, as compared to previous implementations in the literature.

Originality/value

The paper proposes a neural network architecture and is trained with two different learning methodologies, namely, supervised and physics-based. The working of the network along with the different learning methodologies is validated over several EM problems with varying levels of complexity. Furthermore, a comparative study is performed regarding performance accuracy and computational cost to establish the efficacy of different architectures and learning methodologies.

Available. Open Access. Open Access
Article
Publication date: 28 February 2023

Dennis Albert, Lukas Daniel Domenig, Philipp Schachinger, Klaus Roppert and Herwig Renner

The purpose of this paper is to investigate the applicability of a direct current (DC) hysteresis measurement on power transformer terminals for the subsequent hysteresis model…

761

Abstract

Purpose

The purpose of this paper is to investigate the applicability of a direct current (DC) hysteresis measurement on power transformer terminals for the subsequent hysteresis model parametrization in transformer grey box topology models.

Design/methodology/approach

Two transformer topology models with two different hysteresis models are used together with a DC hysteresis measurement via the power transformer terminals to parameterize the hysteresis models by means of an optimization. The calculated current waveform with the derived model in the transformer no-load condition is compared to the measured no-load current waveforms to validate the model.

Findings

The proposed DC hysteresis measurement via the power transformer terminals is suitable to parametrize two hysteresis models implemented in transformer topology models to calculate the no-load current waveforms.

Originality/value

Different approaches for the measurement and utilization of transformer terminal measurements for the hysteresis model parametrization are discussed in literature. The transformer topology models, derived with the presented approach, are able to reproduce the transformer no-load current waveform with acceptable accuracy.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 42 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 16 November 2010

Christian Magele, Michael Jaindl, Alice Köstinger, Werner Renhart, Bogdan Cranganu‐Cretu and Jasmin Smajic

The purpose of this paper is to extend a (μ/ρ, λ) evolution strategy to perform remarkably more globally and to detect as many solutions as possible close to the Pareto optimal…

238

Abstract

Purpose

The purpose of this paper is to extend a (μ/ρ, λ) evolution strategy to perform remarkably more globally and to detect as many solutions as possible close to the Pareto optimal front.

Design/methodology/approach

A C‐link cluster algorithm is used to group the parameter configurations of the current population into more or less independent clusters. Following this procedure, recombination (a classical operator of evolutionary strategies) is modified. Recombination within a cluster is performed with a higher probability than recombination of individuals coming from detached clusters.

Findings

It is shown that this new method ends up virtually always in the global solution of a multi‐modal test function. When applied to a real‐world application, several solutions very close to the front of Pareto optimal solutions are detected.

Research limitations/implications

Stochastic optimization strategies need a very large number of function calls to exhibit their ability to reach very good local if not the global solution. Therefore, the application of such methods is still limited to problems where the forward solutions can be obtained with a reasonable computational effort.

Originality/value

The main improvement is the usage of approximate number of isolated clusters to dynamically update the size of the population in order to save computation time, to find the global solution with a higher probability and to use more than one objective function to cover a larger part of the Pareto optimal front.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 15 November 2011

Werner Renhart, Mario Bellina, Christian Magele and Alice Köstinger

The purpose of this paper is to achieve a very accurate localization of hidden metallic objects in human medicine applications.

139

Abstract

Purpose

The purpose of this paper is to achieve a very accurate localization of hidden metallic objects in human medicine applications.

Design/methodology/approach

The proposed methodology takes advantage of the eddy current effect within a metallic object. Its magnetic reaction field will be measured, e.g. with giant magnetic resistor (GMR) sensors.

Findings

A comparison of measurements and numerical results obtained by finite element computations demonstrate the reliability and positively gives a clue about the feasibility of the suggested method.

Research limitations/implications

While measuring noisy signals, the use of a lock‐in amplifier is rather expensive; especially, in applications with a high number of GMR sensors the use of channel multiplexer must be considered, which again may generate noise.

Originality/value

The paper shows how appropriate shielding of external fields in the measurement setup ensures results of satisfying quality.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 30 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

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