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  • 1.
    Ivanenko, Yevhen
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Estimation of electromagnetic material properties with application to high-voltage power cables2017Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Efficient design of high-voltage power cables is important to achieve an economical delivery of electric power from wind farms and power plants over the very long distances as well as the overseas electric power. The main focus of this thesis is the investigation of electromagnetic losses in components of high-voltage power cables. The objective of the ongoing research is to develop the theory and optimization techniques as tools to make material choices and geometry designs to minimize the high-frequency attenuation and dispersion for HVDC power cables and the power losses associated with HVAC cables. Physical limitations, dispersion relationships and the application of sum rules as well as convex optimization will be investigated to obtain adequate physical insight and a priori modeling information for these problems.

    For HVAC power cables, the objectives are addressed by performing measurements and estimation of complex valued permeability of cable armour steel in Papers I and II. Efficient analytical solutions for the electromagnetic field generated by helical structures with applications for HVAC power cables have been obtained in Paper III.

    For HVDC power cables, estimation of insulation characteristics from dielectric spectroscopy data using Herglotz functions, convex optimization and B-splines, has been investigated in Papers V and VI. The unique solution requirements in waveguide problems have been reviewed in Paper IV.

  • 2.
    Ivanenko, Yevhen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Custafsson, Mats
    Lund University.
    Jonsson, B. L. G.
    KTH Royal Instute of Technology.
    Luger, Annemarie
    Stockholm University.
    Nilsson, Börje
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för matematik (MA).
    Nordebo, Sven
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Toft, Joachim
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för matematik (MA).
    Passive Approximation and Optimization Using B-Splines2019Ingår i: SIAM Journal on Applied Mathematics, ISSN 0036-1399, E-ISSN 1095-712X, Vol. 79, nr 1, s. 436-458Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A passive approximation problem is formulated where the target function is an arbitrary complex-valued continuous function defined on an approximation domain consisting of a finite union of closed and bounded intervals on the real axis. The norm used is a weighted L-p-norm where 1 <= p <= infinity. The approximating functions are Herglotz functions generated by a measure with Holder continuous density in an arbitrary neighborhood of the approximation domain. Hence, the imaginary and the real parts of the approximating functions are Holder continuous functions given by the density of the measure and its Hilbert transform, respectively. In practice, it is useful to employ finite B-spline expansions to represent the generating measure. The corresponding approximation problem can then be posed as a finite-dimensional convex optimization problem which is amenable for numerical solution. A constructive proof is given here showing that the convex cone of approximating functions generated by finite uniform B-spline expansions of fixed arbitrary order (linear, quadratic, cubic, etc.) is dense in the convex cone of Herglotz functions which are locally Holder continuous in a neighborhood of the approximation domain, as mentioned above. As an illustration, typical physical application examples are included regarding the passive approximation and optimization of a linear system having metamaterial characteristics, as well as passive realization of optimal absorption of a dielectric small sphere over a finite bandwidth.

  • 3.
    Ivanenko, Yevhen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Dalarsson, Mariana
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Nordebo, Sven
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Bayford, Richard
    Middlesex University, UK.
    On the plasmonic resonances in a layered waveguide structure2018Ingår i: 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials), IEEE, 2018, s. 188-190Konferensbidrag (Refereegranskat)
    Abstract [en]

    An optimal plasmonic resonance and the associated Fröhlich resonance frequency are derived for a thin layer in a straight waveguide in TM mode. The layer consists of an arbitrary composite material with a Drude type of dispersion. The reflection and transmission coefficients of the layer are analyzed in detail. To gain insight into the behavior of a thin plasmonic layer, an asymptotic expansion to the first order is derived with respect to the layer permittivity.

  • 4.
    Ivanenko, Yevhen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Gustafsson, Mats
    Lund University.
    Jonsson, B.L.G.
    KTH Royal Institute of Technology.
    Luger, Annemarie
    Stockholm University.
    Nilsson, Börje
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för matematik (MA).
    Nordebo, Sven
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Toft, Joachim
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för matematik (MA).
    Passive approximation and optimization with B-splines2017Rapport (Övrigt vetenskapligt)
    Abstract [en]

    A passive approximation problem is formulated where the target function is an arbitrary complex valued continuous function defined on an approximation domain consisting of a closed interval of the real axis. The approximating function is any Herglotz function with a generating measure that is absolutely continuous with Hölder continuous density in an arbitrary neighborhood of the approximation domain. The norm used is induced by any of the standard Lp-norms where 1 ≤ p ≤ ∞. The problem of interest is to study the convergence properties of simple Herglotz functions where the generating measures are given by finite B-spline expansions, and where the real part of the approximating functions are obtained via the Hilbert transform. In practice, such approximations are readily obtained as the solution to a finite- dimensional convex optimization problem. A constructive convergence proof is given in the case with linear B-splines, which is valid for all Lp-norms with 1 ≤ p ≤ ∞. A number of useful analytical expressions are provided regarding general B-splines and their Hilbert transforms. A typical physical application example is given regarding the passive approximation of a linear system having metamaterial characteristics. Finally, the flexibility of the optimization approach is illustrated with an example concerning the estimation of dielectric material parameters based on given dispersion data. 

  • 5.
    Ivanenko, Yevhen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Nedic, Mitja
    Stockholm University.
    Gustafsson, Mats
    Lund University.
    Jonsson, B. L. G.
    KTH Royal Institute of Technology.
    Luger, Annemarie
    Stockholm University.
    Nordebo, Sven
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Quasi-Herglotz functions and convex optimization2018Rapport (Övrigt vetenskapligt)
    Abstract [en]

    We introduce the set of quasi-Herglotz functions and demonstrate that it has properties useful in the modeling of non-passive systems. The linear space of quasi-Herglotz functions constitutes a natural extension of the convex cone of Herglotz functions. It consists of differences of Herglotz functions, and we show that several of the important properties and modeling perspectives of Herglotz functions are inherited by the new set of quasi-Herglotz functions. In particular, this applies to their integral representations, the associated integral identities or sum rules (with adequate additional assumptions), their boundary values on the real axis and the associated approximation theory. Numerical examples are included to demonstrate the modeling of a non-passive gain media formulated as a convex optimization problem,where the generating measure is modeled by using a finite expansion of B-splines and point masses.

  • 6.
    Ivanenko, Yevhen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Nordebo, Sven
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Approximation of dielectric spectroscopy data with Herglotz functions on the real line and convex optimization2016Ingår i: Proceedings of the  2016 18th International Conference on Electromagnetics in Advanced Applications, IEEE, 2016, s. 863-866Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes the ongoing research on approximation of frequency dielectric spectroscopy measurement data. The algorithm based on passive approximation, Hilbert transform and Tikhonov regularization for non-uniformly sampled data is derived. The interpolation and extrapolation problems with application to the dielectric spectroscopy measurement data are solved using convex optimization. 

  • 7.
    Ivanenko, Yevhen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Nordebo, Sven
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Cylindrical multipole expansion for periodic sources with applications for three-phase power cables2016Konferensbidrag (Övrigt vetenskapligt)
  • 8.
    Ivanenko, Yevhen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Nordebo, Sven
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Estimation of complex valued permeability of cable armour steel2016Ingår i: 2016 URSI International Symposium on Electromagnetic Theory (EMTS), IEEE Press, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a model based technique to estimate the complex valued permeability of cable armour steel. An efficient analytical model is derived for the linearized mutual impedance of a transformer coil built on a core of magnetic armour steel. A numerical residue calculation is used to solve the related inverse problem based on impedance data. The analytical model is validated using commercial finite element (FEM) software to establish that edge effects can be neglected. The numerical residue calculation is investigated by studying its convergence based on a simple rectangular quadrature rule in comparison to the composite Simpson's rule. When there are no measurement errors, both methods converge with an unexpected high order (superconvergence). However, in practice the estimation performance will be governed by measurement and model errors. Assuming that there are Gaussian measurement errors, the present performance of the estimation technique is quantified and investigated by means of the Cramér-Rao lower bound. In future, the proposed method will be useful as an input to general calculations of power losses in three-phase power cables.

  • 9.
    Ivanenko, Yevhen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Nordebo, Sven
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Estimation of electromagnetic parameters of cable steel2015Ingår i: Progress in Electromagnetics Research Symposium (PIERS), Prague, Czech Republic, 6-9 July 2015, Electromagnetics Academy , 2015, s. 1068-Konferensbidrag (Övrigt vetenskapligt)
  • 10.
    Ivanenko, Yevhen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Nordebo, Sven
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Measurements and estimation of the complex valued permeability of magnetic steel2015Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This report is intended as a tutorial on electromagnetic modeling to measure and estimate the complex valued relative permeability of magnetic steel. The main application is with the estimation of the electromagnetic material parameters of the armour wires used with high-voltage AC power cables.

    When the magnetic field intensity is sufficiently far from saturating the magnetic steel, the magnetic hysteresis phenomena can be approximated by using a linearization approach based on a complex valued (and frequency and amplitude dependent) relative permeability. In the report it is demonstrated how the complex valued permeability of magnetic steel can be efficiently estimated in the presence of a strong skin-effect. This is achieved by using a simple transformer coil built on the magnetic steel to be tested and by efficient numerical modeling based on waveguide theory and complex analysis. Numerical computations based on the Finite Element Method (FEM) and the commercial software COMSOL are employed to establish when edge effects can be ignored in the simplified analytical model.

  • 11.
    Ivanenko, Yevhen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Nordebo, Sven
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Passive approximation and optimization with B-splines2017Ingår i: 2nd URSI GASS, Montreal, 19–26 August 2017, URSI , 2017, s. 2290-2293Konferensbidrag (Refereegranskat)
  • 12.
    Ivanenko, Yevhen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Nordebo, Sven
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Passive Approximation with High-Order B-Splines2019Ingår i: Analysis, Probability, Applications, and Computation / [ed] Karl‐Olof Lindahl, Torsten Lindström, Luigi G. Rodino, Joachim Toft, Patrik Wahlberg, Birkhäuser Verlag, 2019, s. 83-94Konferensbidrag (Refereegranskat)
    Abstract [en]

    Convex optimization has emerged as a well-suited tool for passive approximation. Here, it is desired to approximate some pre-defined non-trivial system response over a given finite frequency band by using a passive system. This paper summarizes some explicit results concerning the Hilbert transform of general B-splines of arbitrary order and arbitrary partitions that can be useful with the convex optimization formulation. A numerical example in power engineering is included concerning the identification of some model parameters based on measurements on high-voltage insulation materials.

  • 13.
    Nilsson, Börje
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för matematik (MA).
    Ioannidis, Andreas
    Hellenic Naval Academy, Greece.
    Ivanenko, Yevhen
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Nordebo, Sven
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    On absence of sources at infinity and uniqueness for waveguide solutions2016Ingår i: Proceedings of the 2016 18th International Conference on Electromagnetics in Advanced Applications, ICEEA 2016, IEEE Press, 2016, s. 780-783Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper discusses criteria for establishing uniqueness of wave propagation problems. Causality, or passivity that implies causality, is adopted as the fundamental principle. It is stressed that radiation conditions are not applicable for waveguide modes that carry no active power. The Jones' criteria for causality in the frequency domain, which covers the convectively unstable case, are presented and analysed, the vanishing absorption principle, VAP, in particular. It is proposed to use L2 for a lossy medium but a weighted L2 for the lossless case.

  • 14.
    Nordebo, Sven
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Dalarsson, Mariana
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Ivanenko, Yevhen
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Sjöberg, Daniel
    Lund University.
    Bayford, Richard
    Middlesex University, UK.
    On the physical limitations for radio frequency absorption in gold nanoparticle suspensions2017Ingår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 50, nr 15, artikel-id 155401Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a study of the physical limitations for radio frequency absorption in gold nanoparticle (GNP) suspensions. A spherical geometry is considered consisting of a spherical suspension of colloidal GNPs characterized as an arbitrary passive dielectric material which is immersed in an arbitrary lossy medium. A relative heating coefficient and a corresponding optimal near field excitation are defined, taking the skin effect of the surrounding medium into account. The classical Mie theory for lossy media is also revisited, and it is shown that the optimal permittivity function yielding a maximal absorption inside the spherical suspension is a conjugate match with respect to the surrounding lossy material. A convex optimization approach is used to investigate the broadband realizability of an arbitrary passive material to approximate the desired conjugate match over a finite bandwidth, similar to the approximation of a metamaterial. A narrowband realizability study shows that for a surrounding medium consisting of a weak electrolyte solution, the electromagnetic heating, due to the electrophoretic (plasmonic) resonance phenomena inside the spherical GNP suspension, can be significant in the microwave regime, provided that the related Drude parameters can be tuned into (or near to) resonance. As a demonstration, some realistic Drude parameters are investigated concerning the volume fraction, mass, and friction constant of the GNPs. The amount of charge that can be accommodated by the GNPs is identified as one of the most important design parameters. However, the problem of reliably modelling, measuring and controlling the charge number of coated GNPs is not yet fully understood, and is still an open research issue in this field. The presented theory and related physical limitations provide a useful framework for further research in this direction. Future research is also aimed at an expansion towards arbitrary suspension geometries and the inclusion of thermodynamical analysis.

  • 15.
    Nordebo, Sven
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Dalarsson, Mariana
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Ivanenko, Yevhen
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Sjöberg, Daniel
    Lund University, Sweden.
    Bayford, Richard
    Middlesex University, UK.
    Parameter studies on optimal absorption and electrophoretic resonances in lossy media2017Ingår i: 32nd General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2017, IEEE, 2017, s. 1768-1769Konferensbidrag (Refereegranskat)
  • 16.
    Nordebo, Sven
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Gustafsson, Mats
    Lund University.
    Ivanenko, Yevhen
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Nilsson, Börje
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för matematik (MA).
    Sjöberg, Daniel
    Lund University.
    Cylindrical multipole expansion for periodic sources with applications for three-phase power cables2018Ingår i: Mathematical methods in the applied sciences, ISSN 0170-4214, E-ISSN 1099-1476, Vol. 41, nr 3, s. 959-965Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a c ylindrical multipole expansion for periodic sources with applications for three-phase power cables.It is the aim of the contribution to provide some analytical solutions and techniques that can be useful in the calculation ofcable losses. Explicit analytical results are given for the fields generated by a three-phase helical current distribution andwhich can be computed efficiently as an input to other numerical methods such as, for example , the Method of Moments.It is shown that the field computations are numerically stable at low frequencies (such as 50 Hz) as well as in the quasi-magnetostatic limit provided that sources are divergence-free. The cylindrical multipole expansion is fur thermore usedto derive an efficient analytical model of a measurement coil to measure and estimate the complex valued permeability ofmagnetic steel armour in the presence of a strong skin-effect.

  • 17.
    Nordebo, Sven
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Ivanenko, Yevhen
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Periodic Green's dyadics for helical current distributions2015Ingår i: Progress in Electromagnetics Research Symposium (PIERS), Electromagnetics Academy , 2015, s. 1069-Konferensbidrag (Övrigt vetenskapligt)
  • 18.
    Nordebo, Sven
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Stumpf, Martin
    Brno Univ Technol, Czech Republic.
    Ivanenko, Yevhen
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    A multi-resolution 4-D FFT approach to parametric boundary integral equations for helical structures2016Ingår i: 2016 URSI International Symposium on Electromagnetic Theory (EMTS), IEEE Press, 2016, s. 218-221Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper gives a report of an ongoing research to develop parametric boundary integral equations for helical structures and their application in the computation of induced currents and losses in three-phase power cables. The proposed technique is formulated in terms of the Electric Field Integral Equation (EFIE) or the Magnetic Field Integral Equation (MFIE) for a penetrable object together with the appropriate periodic Green's functions and a suitable parameterization of the helical structure. A simple and efficient numerical scheme is proposed for the computation of the impedance matrix in the Method of Moments (MoM) which is based on a multi-resolution 4-D FFT computation followed by polynomial extrapolation. Numerical examples are included demonstrating that the singular integrals have almost linear convergence and hence that linear or quadratic extrapolation can be used to yield accurate results.

1 - 18 av 18
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