International Journal of Applied Electromagnetics and Mechanics - Volume 60, issue S1

Authors: Baumgarten, Daniel

Article Type: Editorial

DOI: 10.3233/JAE-191100

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 60, no. S1, pp. S1-S1, 2019

Authors: Alnajjar, Belal M.K. | Buchau, André | Anders, Jens | Blümich, Bernhard

Article Type: Research Article

Abstract: An H-shaped low-field permanent magnet is presented. It has been designed, simulated and optimized using the finite element method. The magnet mainly consists of two poles, each of which consists of 37 hexagonal magnetic blocks that are magnetically connected by an iron yoke. To achieve the magnetic field homogeneity in the ppm range required for NMR applications, mechanical shimming by a vertical adjustment of the hexagonal magnetic blocks has been applied. Here, the displacement of each block from the initial equidistant symmetric design has been optimized by applying a pattern search method. In addition, two pole pieces made of iron …have been added to the magnet to further improve the magnetic field homogeneity. The dimensions of these pole pieces have been optimized using a genetic algorithm. The magnetic field homogeneity of 15 ppm (parts per million) measured inside the manufactured prototype verifies the accuracy of the proposed simulation based design approach. Show more

Keywords: Finite element methods, genetic algorithms, mobile NMR, NMR magnet, permanent magnet design, pattern search algorithms, shimming

DOI: 10.3233/JAE-191101

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 60, no. S1, pp. S3-S14, 2019

Authors: Moreno, Sinvaldo R. | Klein, Carlos E. | Mariani, Viviana C. | Coelho, Leandro dos S. | Alotto, Piergiorgio | Torchio, Riccardo | Bauernfeind, Thomas | Baumgartner, Paul

Article Type: Research Article

Abstract: This paper presents the application of the Partial Element Equivalent Circuit (PEEC) approach, which is a full wave electromagnetic modelling technique for conductors embedded in arbitrary dielectrics based on equivalent circuits, to the optimal design of antennas with non-uniform spacing between the array elements. The design optimization problem is solved by means of the new nature-inspired Cheetah metaheuristic. The main aim of this paper is to introduce the Cheetah optimization algorithm to the electromagnetics and antenna community. The results are compared to two well-known optimization algorithms and to show the effectiveness of the proposed algorithm on a realistic benchmark problem.

Keywords: Antenna array, Cheetah optimization algorithm, genetic algorithm, partial element equivalent circuit, particle swarm optimization algorithm

DOI: 10.3233/JAE-191102

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 60, no. S1, pp. S15-S24, 2019

Authors: Cirimele, Vincenzo | Dimauro, Luca | Repetto, Maurizio | Bonisoli, Elvio

Article Type: Research Article

Abstract: This paper proposes the study of a magnetic gear by means of multi-objective optimisation. Magnetic gears are structures able to transfer motion between two or more mechanical axles with a given speed ratio. In this aspect they are analogous to a classical mechanical gear but they allow to transfer motion without contact between the moving parts. To replace a standard mechanical gear in an automotive powertrain, the design of a magnetic gear able to transfer the torque needed by the application is required. At the same time, beside the torque, the replacement of the mechanical gear should not alter the …dynamic of the powertrain so that also mechanical parameters, as for instance the moment of inertia, must be considered in the design. To cope with these requirements, a multi-objective optimisation approach is proposed that maximises the transmitted torque per unit mass of the magnetic gear while minimising the moment of inertia of the moving parts. Due to the computational intensive evaluation of the magnetic performance, the optimisation is carried out by a deterministic optimisation algorithm coupled to a weighted sum approach of objectives. Results are discussed and compared with those of a commercial application. Show more

Keywords: Electromechanics, magnetic gears, multi-objective optimization, automotive

DOI: 10.3233/JAE-191103

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 60, no. S1, pp. S25-S34, 2019

Authors: Diampovesa, Sephora | Hubert, Arnaud | Yvars, Pierre-Alain | Meyer, Yann | Zimmer, Laurent

Article Type: Research Article

Abstract: In electrical engineering, current methods show limits when it comes to complex design problems with heterogeneous and multidisciplinary requirements in the preliminary steps. Also, the setting and the solving of those problems is a simultaneous challenge that needs to be more explored. It may be necessary to recall the need to re-think the conventional design process when it comes to complex electrical systems. Particularly, by considering first the problem admissibility before its solving or optimization. Being able to detect an ill-posed or an over-constrained problem (causal analysis) can help in finding admissible solutions but also forces the designers to understand …the meaning of the problem modeling. A synthesis point of view is proposed to ensure admissible and relevant solutions during the preliminary design (pre-design) process. Intervals and constraint-based methods are shown suitable for proposing efficient modeling, solving tools and addressing optimal design. This paper is illustrated by the case study of a benchmark transformer, taking into account multi-physical requirements. The optimal design includes mixed-type variables and tabulated constraints such as manufacturer datasheets. The computed results are then compared with solutions found in the literature and show the advantages of the implemented method in terms of solutions and computation time. Show more

Keywords: Optimal design, interval methods, constraints satisfaction problems, pre-design of electromagnetic devices

DOI: 10.3233/JAE-191104

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 60, no. S1, pp. S35-S48, 2019

Authors: Formisano, Alessandro | Martone, Raffaele

Article Type: Research Article

Abstract: The resolution of inverse problems is a quite common task in the diagnostic processes based on electromagnetic field measurements, in particular when internal characteristics of the object under test must be estimated from external measurements. This class of problems are well known to be ill posed, and a number of different regularization techniques have been proposed to make the estimation process reliable. In this paper, with reference to an application in the framework of low frequency magnetic fields measurements, a comparison of some regularization techniques is presented, in order to highlight advantages and drawbacks of each in the proposed application.

Keywords: Inverse problems, magnetic measurements, regularization, tolerance assessment

DOI: 10.3233/JAE-191105

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 60, no. S1, pp. S49-S62, 2019

Authors: Haltmeier, Markus | Zangerl, Gerhard | Schier, Peter | Baumgarten, Daniel

Article Type: Research Article

Abstract: Magnetorelaxometry imaging is a novel tool for quantitative determination of the spatial distribution of magnetic nanoparticle inside an organism. The use of multiple excitation patterns has been demonstrated to significantly improve spatial resolution. However, increasing the number of excitation patterns is considerably more time consuming, because several sequential measurements have to be performed. In this paper, we use compressed sensing in combination with sparse recovery to reduce the total measurement time and to improve spatial resolution. For image reconstruction, we propose using the Douglas-Rachford splitting algorithm applied to the sparse Tikhonov functional including a positivity constraint. Our numerical experiments …demonstrate that the resulting algorithm is capable to accurately recover the magnetic nanoparticle distribution from a small number of activation patterns. For example, our algorithm applied with 10 activations yields half the reconstruction error of quadratic Tikhonov regularization applied with 50 activations, for a tumor-like phantom. Show more

Keywords: Compressed sensing, magnetorelaxometry, image reconstruction, magnetic nanoparticles, multiple excitation, Douglas-Rachford splitting, sparse recovery

DOI: 10.3233/JAE-191106

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 60, no. S1, pp. S63-S78, 2019

Authors: Hiruma, Shingo | Igarashi, Hajime

Article Type: Research Article

Abstract: This paper introduces a new method for fast computing of the iron and copper losses in electromagnetic systems. In the method, the finite element equation is reduced to the equivalent Cauer circuit via model order reduction. The nonlinear property due to core saturation is pre-computed and included in the Cauer circuit. While the copper loss is computed as the Jule loss in the circuit, the iron loss is computed in the post process by restoring the field distribution from the solution to the circuit equation with aid of the proper orthogonal decomposition.

Keywords: Cauer circuit, eddy current problems, equivalent circuit, proper orthogonal decomposition

DOI: 10.3233/JAE-191107

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 60, no. S1, pp. S79-S86, 2019

Authors: Le Luong, Huong Thao | Messine, Frédéric | Henaux, Carole | Bueno Mariani, Guilherme | Voyer, Nicolas | Mollov, Stefan

Article Type: Research Article

Abstract: Numerical optimization algorithms based on finite element analysis are widely used to design electrical machines, especially with complex geometries. The advantage of these approaches is that they have high accuracy by taking into account nonlinear properties of the materials. However, the computational time is important. In this paper, quasi-Newton based algorithm using fmincon Matlab solver and mesh adaptive direct search based algorithm using NOMAD solver are compared by testing several relaxed design problems in order to find an appropriate algorithm for our optimization problem. Finally, we achieve the optimal solution and the shape of the optimal machine is …then validated. Show more

Keywords: Design optimization, NOMAD , fmincon , finite element analysis, wound rotor synchronous machine

DOI: 10.3233/JAE-191108

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 60, no. S1, pp. S87-S100, 2019

Authors: Di Barba, Paolo | Mognaschi, Maria Evelina | Nowak, Tomasz | Blaszczyk, Andreas

Article Type: Research Article

Abstract: A method of free-form optimisation for shaping an electrode surface is proposed in the context of shape design of high voltage devices. The subsequent comparison of various optimisation approaches in dielectric design is developed. In particular, a mesh-based model, driven by free-form optimisation, is presented and compared with a parameter-based model and a NURBS-based model driven by parametric optimisation algorithms. In each model, the electric field analysis is computed by means of the Boundary Element Method. In order to assess the proposed method in a comparative way, the optimal shape design of a L-shaped tunnel electrode and a ring electrode …are considered as the case studies. Show more

Keywords: Free-form optimisation, shape design, dielectrics, boundary element method

DOI: 10.3233/JAE-191109

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 60, no. S1, pp. S101-S113, 2019