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Article
Publication date: 11 September 2009

I.M.V. Caminiti, A. Formisano, M.C. Lupoli and R. Martone

The purpose of this paper is to propose the optimal allocation and alignment of probes for current distribution measurement (CDM) in the case of twin cable in conduit conductor…

Abstract

Purpose

The purpose of this paper is to propose the optimal allocation and alignment of probes for current distribution measurement (CDM) in the case of twin cable in conduit conductor (CICC) cables with equal and opposite current.

Design/methodology/approach

The most effective approach to CDM in CICC cables is to perform indirect measurements starting from magnetic field map measured externally to the cable. A number of approaches have been proposed to optimize the layout of magnetic field probes external to the cable, but all dealing with single cables. In this paper, an approach to the optimized design of measurement system for twin cables will be proposed, based on the minimization of a suitable cost function.

Findings

A method for the optimal allocation of probes both in terms of rejection of the background field and of condition number of the Green matrix has been defined.

Research limitations/implications

The method is valid only in the hypothesis of linear relationship between currents and magnetic field.

Practical implications

The proposed approach allows to design more robust CDM systems, with increased noise and background field rejection capability.

Originality/value

The problem of optimal design of CDM systems has been previously tackled in literature, but typically with reference to single cables. In the paper, an approach able to explicitly deal with twin cables is proposed.

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

Article
Publication date: 1 September 2005

A. Formisano

Inverse problems are usually ill‐conditioned, requiring the adoption of regularization techniques to obtain reliable results. The choice of the regularization method and of the…

Abstract

Purpose

Inverse problems are usually ill‐conditioned, requiring the adoption of regularization techniques to obtain reliable results. The choice of the regularization method and of the related parameters represents a critical issue that must be based on the knowledge of reliable additional information on the problem. In the paper some possibilities and pitfalls for the choice of regularization strategy are presented and compared.

Design/methodology/approach

Electromagnetic inverse problems (EIP) are usually formulated starting from a direct problem, based on a direct operator, providing the effects (e.g. fields, fluxes) generated by known sources acting through known systems. The direct operators involved in many real world electromagnetic phenomena, due to their compactness, lead to ill posed inverse problems. Inversion procedures pursue the solution regularity through the adoption of various regularization techniques. Improper use of regularizations may unduly constrain the approximated solution and, consequently, cause significant lack of accuracy. Mathematical tools for an effective choice of the regularization technique are not available for every application, and a number of issues are still open. The paper presents a common mathematical model for most of the regularization techniques, discussing their benefits and limitations.

Findings

The paper discusses limits, applicability conditions, and impact on the performance of reconstruction procedures, of some relevant characteristics of the inversion algorithms, with particular reference to robustness against noise and inaccuracies in the system parameters.

Originality/value

Some criteria for an effective application of regularization are also discussed, showing in particular how proper choices, founded on a careful analysis of the direct problem, may reveal quite effective in improving the solution quality.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 24 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 5 January 2015

Andrea Gaetano Chiariello, Alessandro Formisano and Raffaele Martone

Inductances of complex coils, in the presence of linear materials only, can be computed by discretizing coils into simpler elements, whose magnetic behavior is analytically…

Abstract

Purpose

Inductances of complex coils, in the presence of linear materials only, can be computed by discretizing coils into simpler elements, whose magnetic behavior is analytically expressible, and suitably combining elementary contributions. Reliable results require high numbers of elements. In such cases, advantages can be taken from Graphic Processor Unit (GPU) capabilities of dealing efficiently with high numbers of repeated simple computational tasks. The purpose of this paper is to set up a fast and prompt numerical procedure to cope with the above described task.

Design/methodology/approach

The coils are first decomposed into current segments, taking into account accuracy, relative position and shape of coils to determine the number of segments. An analytical formula is then used to compute elementary contributions using GPUs to speed up the process, and finally superposition is used to recover the result.

Findings

The main advantages of the proposed approach are first demonstrated using simple examples, with analytical solutions, to validate the method accuracy and promptness, then more complex cases are taken to demonstrate its generality.

Research limitations/implications

The method is intrinsically limited by the linearity assumption, excluding the presence of magnetic materials. The adopted formulas require in addition that coils must lie in free space.

Practical implications

The proposed method can help in the design of complex coils or coils systems, where the performance depends on total magnetic energy or magnetic forces among coils.

Originality/value

The paper presents an original implementation in GPU-based computational environment of a procedure to compute inductances, based on the superposition of a high number of current segments. The procedure includes an original method to self-adaptively define number and position of current segments used in the coils discretization.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 September 2001

P. Bettini, A. Formisano, R. Martone, A. Stella and F. Trevisan

The equivalent currents method has proven to be particularly effective in the identification of plasma boundary in Tokamak fusion devices. Anyway, the ill‐posedness of the…

Abstract

The equivalent currents method has proven to be particularly effective in the identification of plasma boundary in Tokamak fusion devices. Anyway, the ill‐posedness of the mathematical model to be inverted calls for the adoption of suitable regularization techniques to be adopted, in particular to reduce the influence of the measurement errors. In this paper the equivalent currents method is illustrated, together with some details on its application to the plasma identification. In addition, two algorithms for the optimal choice of the representation basis are presented, together with a discussion about the obtained numerical results.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 20 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 June 2001

A. Formisano, R. Martone and F. Trevisan

The applied research in the thermonuclear fusion area is directed towards the design of a commercial reactor. In such a reactor, the room required for the probes deputised to…

Abstract

The applied research in the thermonuclear fusion area is directed towards the design of a commercial reactor. In such a reactor, the room required for the probes deputised to measure the magnetic field for the identification step of the control system must be kept to a minimum, and the number and position of probes must be optimised. A possible approach to the optimal choice of a set of magnetic probes for the reconstruction of a magnetostatic field, based on a statistical approach, is presented and discussed.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 20 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 September 2005

F. Ferraioli, A. Formisano and R. Martone

Electrical resistive tomography (ERT) is a non‐destructive testing technique based upon the reconstruction of the electrical conductivity profile inside a body from measurement…

Abstract

Purpose

Electrical resistive tomography (ERT) is a non‐destructive testing technique based upon the reconstruction of the electrical conductivity profile inside a body from measurement made on its boundary. In the literature about the inverse problems the ERT is considered still challenging being both non‐linear, ill‐posed and very limited in resolution. Purpose of the paper is to assess the performances of an approach exploiting the circuital behaviour of a particular class of problems, highlighting its advantages in terms of simplicity and reduction of the computer burden.

Design/methodology/approach

In this paper, an electrical property of a particular class of problems is pointed out; the same property is used to formulate in terms of a circuital model the ERT problem. The proposed methodology consists basically of combining properly simplified data previously evaluated and collected. The overall procedure is presented with reference to an underground structure diagnostics problem.

Findings

The effectiveness of the proposed approach has been evaluated quantitatively by comparing the simplified procedure results with the ones obtained by performing fully 3D FEM analysis.

Originality/value

The consistently low errors obtained state the convenience of the method also taking into account that the reconstruction process consists merely in post‐processing previously collected data.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 24 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 11 July 2008

M. Cioffi, P. Di Barba, A. Formisano and R. Martone

This paper seeks to describe an approach to multi‐objective optimization problems (MOOPs) based on game theory (GT) and to provide a comparison with the more standard Pareto…

Abstract

Purpose

This paper seeks to describe an approach to multi‐objective optimization problems (MOOPs) based on game theory (GT) and to provide a comparison with the more standard Pareto approach on a real design problem.

Design/methodology/approach

The GT is first briefly presented, then a possible recasting of MOOPs in terms of GT is described, where players from GT are associated with single objectives and strategies to the choice of degrees of freedom. A comparison with the Pareto approach is performed on the optimized design of a superconducting synchronous generator.

Findings

It was shown that the GT can be applied to the optimized design of real world devices, with results that present a different viewpoint on the problem, yet with device performance comparable with those obtained by standard approaches.

Research limitations/implications

Only the Nash approach to non‐cooperative games has been applied; the conditions for the solution found using GT to belong to the Pareto front have not been fully explored.

Practical implications

Designers and engineers interested in optimal design are presented with a new design technique able to get a balance among conflicting partial objectives, that can also be used to select among different possible designs obtained in other ways (e.g. using the Pareto front approach).

Originality/value

The paper demonstrates the possibility of using GT in the design of real world electromagnetic devices, with reference to the optimal shape design of a high temperature superconducting single‐phase synchronous generator.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 March 2001

V. Cavaliere, A. Formisano and R. Martone

Magnetic resonance is becoming a routine analysis for many applications. Present day devices include active shielding systems instead of passive ferromagnetic shields. This calls…

Abstract

Magnetic resonance is becoming a routine analysis for many applications. Present day devices include active shielding systems instead of passive ferromagnetic shields. This calls for sophisticated design techniques able to provide satisfactory performance in terms of central field homogeneity, reduced stray field and minimal superconductor’s volume. In the paper some of the possible techniques to deal with such a problem are presented and discussed.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 20 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 September 2003

A. Formisano and R. Martone

The problem of reconstructing the current profile in regions not directly accessible by sensors is tackled, with reference to current profile reconstruction in cable in conduit…

Abstract

The problem of reconstructing the current profile in regions not directly accessible by sensors is tackled, with reference to current profile reconstruction in cable in conduit conductors cable. A possible strategy for the choice of the optimal number, location and direction of magnetic probes measuring the field outside the source region is discussed. In addition, some considerations on the related inverse problem resolution are presented.

Details

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

Keywords

Article
Publication date: 16 November 2010

I.M.V. Caminiti, A. Formisano, R. Martone and F. Ferraioli

The purpose of this paper is to evaluate the performances of a resolution scheme able to follow the dynamics of brain tissue properties in combined ElectroEncefaloGraphic (EEG) …

Abstract

Purpose

The purpose of this paper is to evaluate the performances of a resolution scheme able to follow the dynamics of brain tissue properties in combined ElectroEncefaloGraphic (EEG) – MagnetoEncefaloGraphic (MEG) techniques for the brain analysis, minimizing the computation burden.

Design/methodology/approach

The estimation process in combined EEG‐MEG is performed by a Moore‐Penrose pseudo‐inverse computation. This is affected by the uncertain knowledge of the living tissues' electric properties. In principle, it is possible to estimate those properties from the EEG‐MEG signals. The estimation process becomes in this case non‐linear. A resolution scheme is proposed, based on the exploitation of the different dynamics characterizing sources and tissues properties.

Findings

The proposed resolution scheme provides a reasonable estimate of the sources for a computationally affordable frequency of non‐liner estimations.

Research limitations/implications

The proposed approach has not been tested yet on experimental data, and as such, its sensitivity to environmental uncertainty is not known yet.

Practical implications

The proposed strategy can be easily implemented to perform realistic measurement processing.

Originality/value

The paper presents a novel strategy to estimate tissues properties and EEG‐MEG signal sources based on the exploitation of their different dynamics, possibly taking advantages from an impedance tomography preliminary analysis for the tissue properties dynamics.

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

1 – 10 of 147