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  • 1. Aksimsek, Sinan
    et al.
    Cinar, Gökhan
    Nilsson, Börje
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    TEM wave propagation in a coaxial cable with a step discontinuity on the outer wall2012Report (Other academic)
  • 2. Aksimsek, Sinan
    et al.
    Cinar, Gökhan
    Nilsson, Börje
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    TEM wave scattering by a step discontinuity on the outer wall of a coaxial waveguide2013In: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 61, no 8, p. 2783-2791Article in journal (Refereed)
    Abstract [en]

    In this paper, the propagation of TEM waves along a coaxial waveguide with a step discontinuity on its outer wall is investigated rigorously by applying the direct Fourier transform and reducing the problem into the solution of a modified Wiener–Hopf equation. The solution for the field terms are determined in terms of an infinite number of unknown coefficients, which satisfy an infinite set of linear algebraic equations. These equations are solved numerically and the effect of area ratio is presented graphically at the end of the analysis. The same problem is also analyzed by applying the mode-matching technique and the results of the two approaches are compared. It is observed numerically that the Wiener–Hopf technique provides a better convergence than the mode-matching technique.

  • 3. Bernland, Anders
    et al.
    Gustafsson, Mats
    Nordebo, Sven
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Physical limitations on the scattering of electromagnetic vector spherical waves2011In: Journal of Physics A: Mathematical and Theoretical, ISSN 1751-8113, E-ISSN 1751-8121, Vol. 44, no 14, p. Article ID: 145401-Article in journal (Refereed)
  • 4. Bernland, Anders
    et al.
    Gustafsson, Mats
    Nordebo, Sven
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Summation rules and physical bounds for partial wave scattering in electromagnetics2009In: The 9:th International Conference on Mathematical and Numerical Aspects of Waves Propagation, 2009, p. 206-207Conference paper (Refereed)
  • 5.
    Cinar, Gökhan
    et al.
    Eskisehir Osmangazi University, Turkey.
    Aksimsek, Sinan
    Istanbul KÄultÄur University, Turkey.
    Nilsson, Börje
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Cinar, Özge
    Eskisehir Osmangazi University, Turkey.
    Wiener-Hopf analysis of TM wave reflection by a step discontinuity on the junction of two coaxial waveguides with perfectly conducting and impedance walls2015In: Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6-9, 2015, Electromagnetics Academy , 2015, p. 1062-Conference paper (Other academic)
  • 6.
    Dalarsson, Mariana
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    The absorption of electromagnetic (EM) waves by a spherical dilute suspension of nanoparticles2017Report (Other academic)
  • 7.
    Dalarsson, Mariana
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Sjöberg, Daniel
    Lund University.
    Bayford, Richard
    Middlesex Univ, UK.
    Absorption and optimal plasmonic resonances for small ellipsoidal particles in lossy media2017In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 50, no 34, article id 345401Article in journal (Refereed)
    Abstract [en]

    A new simplified formula is derived for the absorption cross section of small dielectric ellipsoidal particles embedded in lossy media. The new expression leads directly to a closed form solution for the optimal conjugate match with respect to the surrounding medium, i.e. the optimal permittivity of the ellipsoidal particle that maximizes the absorption at any given frequency. This defines the optimal plasmonic resonance for the ellipsoid. The optimal conjugate match represents a metamaterial in the sense that the corresponding optimal permittivity function may have negative real part (inductive properties), and can not in general be implemented as a passive material over a given bandwidth. A necessary and sufficient condition is derived for the feasibility of tuning the Drude model to the optimal conjugate match at a single frequency, and it is found that all the prolate spheroids and some of the (not too flat) oblate spheroids can be tuned into optimal plasmonic resonance at any desired center frequency. Numerical examples are given to illustrate the analysis. Except for the general understanding of plasmonic resonances in lossy media, it is also anticipated that the new results can be useful for feasibility studies with e.g. the radiotherapeutic hyperthermia based methods to treat cancer based on electrophoretic heating in gold nanoparticle suspensions using microwave radiation.

  • 8.
    de Gelidi, S.
    et al.
    Middlesex Univ, UK.
    Seifnaraghi, N.
    Middlesex Univ, UK.
    Bardill, A.
    Middlesex Univ, UK.
    Tizzard, A.
    Middlesex Univ, UK.
    Wu, Y.
    UCL, UK.
    Sorantin, E.
    Med Univ Graz, Austria..
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Demosthenous, A.
    UCL, UK.
    Bayford, R.
    Middlesex Univ, UK.
    Torso shape detection to improve lung monitoring2018In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 39, no 7, article id 074001Article in journal (Refereed)
    Abstract [en]

    Objective: Newborns with lung immaturity often require continuous monitoring and treatment of their lung ventilation in intensive care units, especially if born preterm. Recent studies indicate that electrical impedance tomography (EIT) is feasible in newborn infants and children, and can quantitatively identify changes in regional lung aeration and ventilation following alterations to respiratory conditions. Information on the patient-specific shape of the torso and its role in minimizing the artefacts in the reconstructed images can improve the accuracy of the clinical parameters obtained from EIT. Currently, only idealized models or those segmented from CT scans are usually adopted. Approach: This study presents and compares two methodologies that can detect the patient-specific torso shape by means of wearable devices based on (1) previously reported bend sensor technology, and (2) a novel approach based on the use of accelerometers. Main results: The reconstruction of different phantoms, taking into account anatomical asymmetries and different sizes, are produced for comparison. Significance: As a result, the accelerometers are more versatile than bend sensors, which cannot be used on bigger cross-sections. The computational study estimates the optimal number of accelerometers required in order to generate an image reconstruction comparable to the use of a CT scan as the forward model. Furthermore, since the patient position is crucial to monitoring lung ventilation, the orientation of the phantoms is automatically detected by the accelerometer-based method.

  • 9.
    Fhager, Andreas
    et al.
    Chalmers.
    Gustafsson, Mats
    Lund University.
    Nordebo, Sven
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Image reconstruction in microwave tomography using a dielectric Debye model2012In: IEEE Transactions on Biomedical Engineering, ISSN 0018-9294, E-ISSN 1558-2531, Vol. 59, no 1, p. 156-166Article in journal (Refereed)
    Abstract [en]

    In this paper, quantitative dielectric image reconstruction based on broadband microwave measurements is investigated. A time-domain-based algorithm is derived where Debye model parameters are reconstructed in order to take into account the strong dispersive behavior found in biological tissue. The algorithm is tested with experimental and numerical data in order to verify the algorithm and to investigate improvements in the reconstructed image resulting from the improved description of the dielectric properties of the tissue when using broadband data. The comparison is made in relation to the more commonly used conductivity model. For the evaluation, two examples were considered, the first was a lossy saline solution and the second was less lossy tap water. Both liquids are strongly dispersive and used as a background medium in the imaging examples. The results show that the Debye model algorithm is of most importance in the tap water for a bandwidth of more than 1.5 GHz. Also the saline solution exhibits a dispersive behavior but since the losses restrict the useful bandwidth, the Debye model is of less significance even if somewhat larger and stronger artifacts can be seen in the conductivity model reconstructions

  • 10. Fhager, Andreas
    et al.
    Gustafsson, Mats
    Nordebo, Sven
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Persson, Mikael
    A Fisher Information Based Gradient Scaling for Microwave Tomography2007In: Progress In Electromagnetics Research Symposium: Prague, Czech Republic, 27-30 Aug, 2007, 2007Conference paper (Refereed)
  • 11. Fhager, Andreas
    et al.
    Gustafsson, Mats
    Nordebo, Sven
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Persson, Mikael
    A statistical approach to gradient scaling microwave tomography2007In: Proceedings of EMB 07, computational electromagnetics, methods and applications: Lund, Sweden, October 2007, 2007, p. 153-160Conference paper (Refereed)
  • 12. Fhager, Andreas
    et al.
    Gustafsson, Mats
    Nordebo, Sven
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Persson, Mikael
    A Statistically Based Preconditioner for Two-Dimensional Microwave Tomography2007In: Proceedings of The Second International Workshop on Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP2007): St. Thomas, U.S. Virgin Islands, Dec. 12-14 2007, 2007, p. 173-176Conference paper (Refereed)
  • 13.
    Gustafsson, Mats
    et al.
    Lund University.
    Cismasu, Marius
    Lund University.
    Nordebo, Sven
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Absorption Efficiency and Physical Bounds on Antennas2010In: International Journal of Antennas and Propagation, ISSN 1687-5869, E-ISSN 1687-5877, Vol. 2010, article id 946746Article in journal (Refereed)
    Abstract [en]

    The all spectrum absorption efficiency appears in the physical bounds on antennas expressed in the polarizability dyadics. Here, it is shown that this generalized absorption efficiency is close to 1/2 for small idealized dipole antennas and for antennas with a dominant resonance in their absorption. Also, the usefulness of this parameter is analyzed for estimation of antenna performance. The results are illustrated with numerical data for several antennas.

  • 14. Gustafsson, Mats
    et al.
    Kristensson, Gerhard
    Nordebo, Sven
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Larsson, Christer
    Bernland, Anders
    Sjöberg, Daniel
    Physical bounds and sum rules in scattering and antenna theory2009In: Electromagnetics in Advanced Applications, 2009. ICEAA '09. International Conference on, 2009, p. 600-603Conference paper (Refereed)
    Abstract [en]

    The objective of this paper is to review some recently developed sum rules and physical bounds in scattering and antenna theory. The sum rules are based on identities for Herglotz functions that relate the quantity of interest integrated over all wavelengths with its static polarizability dyadics. They are transformed to physical bounds by applying variational principles for the polarizability dyadics together with various estimates of the integrals. The theoretical findings are exemplified by numerical results for several configurations.

  • 15. Gustafsson, Mats
    et al.
    Nordebo, Sven
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Bandwidth, Q factor, and resonance models of antennas2006In: Progress in Electromagnetics Research PIER, Vol. 62, p. 1-20Article in journal (Refereed)
    Abstract [en]

    In this paper, we introduce a first order accurate resonance model based on a second order Pade approximation of the reflection coefficient of a narrowband antenna. The resonance model is characterized by its Q factor, given by the frequency derivative of the reflection coefficient. The Bode-Fano matching theory is used to determine the bandwidth of the resonance model and it is shown that it also determines the bandwidth of the antenna for sufficiently narrow bandwidths. The bandwidth is expressed in the Q factor of the resonance model and the threshold limit on the reflection coefficient. Spherical vector modes are used to illustrate the results. Finally, we demonstrate the fundamental difficulty of finding a simple relation between the Q of the resonance model, and the classical Q defined as the quotient between the stored and radiated energies, even though there is usually a close resemblance between these entities for many real antennas.

  • 16. Gustafsson, Mats
    et al.
    Nordebo, Sven
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Characterization of MIMO Antennas using Spherical Vector Waves2006In: IEEE Transactions on Antennas and Propagation, Vol. 54, no 9, p. 2679-2682Article in journal (Refereed)
  • 17. Gustafsson, Mats
    et al.
    Nordebo, Sven
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Cramer-Rao Lower Bounds for Inverse Scattering Problems of Multilayer Structures2006In: Inverse Problems, Vol. 22, p. 1359-1380Article in journal (Refereed)
    Abstract [en]

    In this paper, the inverse scattering problem of amultilayer structure is analysed with the Fisher information matrix and the Cramer–Rao lower bound (CRLB). The CRLB quantifies the ill-posedness of the inverse scattering problem in terms of resolution versus estimation accuracy based on the observation of noisy data. The limit for feasible inversion is identified by an asymptotic eigenvalue analysis of the Toeplitz Fisher information matrix and an application of the sampling theorem. It is shown that the resolution is inversely proportional to the bandwidth of the reflection data and that the CRLB increases linearly with the number of slabs. The transmission data give a rank-1 Fisher information matrix which can approximately reduce the CRLB by a factor of 4. Moreover, the effect of dispersive material parameters and simultaneous estimation of two material parameters are analysed. The results are illustrated with numerical examples.

  • 18. Gustafsson, Mats
    et al.
    Nordebo, Sven
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    On the spectral efficiency of a sphere2007In: Progress in Electromagnetics Research PIER, Vol. 67, p. 275-296Article in journal (Refereed)
  • 19.
    Gustafsson, Mats
    et al.
    Lund University.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Optimal Antenna Currents for Q, Superdirectivity, and Radiation Patterns Using Convex Optimization2013In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 61, no 3, p. 1109-1118Article in journal (Refereed)
    Abstract [en]

    The high Q-factor (low bandwidth) and low efficiency make the design of small antennas challenging. Here, convex optimization is used to determine current distributions that provide upper bounds on the antenna performance. Optimization formulations for maximal gain Q-factor quotient, minimal Q-factor for superdirectivity, and minimum Q for given far-fields are presented. The effects of antennas embedded in structures are also discussed. The results are illustrated for planar geometries.

  • 20. Gustafsson, Mats
    et al.
    Sohl, Christian
    Kristensson, Gerhard
    Nordebo, Sven
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Larsson, Christer
    Bernland, Anders
    Sjöberg, Daniel
    An overview of some recent physical bounds in scattering and antenna theory2009In: 3rd European Conference on Antennas and Propagation, 2009, p. 1795-1798Conference paper (Refereed)
  • 21. Gustafsson, Mats
    et al.
    Sohl, Christian
    Nordebo, Sven
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Physical bounds on the antenna scattering matrix2008In: 2008 IEEE Antennas and Propagation Society International Symposium, IEEE , 2008Conference paper (Refereed)
  • 22.
    Gustafsson, Stefan
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Biro, Thomas
    Jönköping University.
    Cinar, Gökhan
    Gebze Institute of Technology, Gebze, Kocaeli, Turkey.
    Gustafsson, Mats
    Lund University.
    Karlsson, Anders
    Lund University.
    Nilsson, Börje
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Sjöberg, Mats
    ABB AB, Karlskrona.
    Electromagnetic dispersion modeling and measurements for HVDC power cables2014In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 29, no 6, p. 2439-2447Article in journal (Refereed)
    Abstract [en]

    This paper provides a general framework for electromagnetic (EM) modeling, sensitivity analysis, computation, and measurements regarding the wave propagation characteristics of high-voltage direct-current (HVDC) power cables. The modeling is motivated by the potential use with transient analysis, partial-discharge measurements, fault localization and monitoring, and is focused on very long (10 km or more) HVDC power cables with transients propagating in the low-frequency regime of about 0-100 kHz. An exact dispersion relation is formulated together with a discussion on practical aspects regarding the computation of the propagation constant. Experimental time-domain measurement data from an 80-km-long HVDC power cable are used to validate the electromagnetic model, and a mismatch calibration procedure is devised to account for the connection between the measurement equipment and the cable. Quantitative sensitivity analysis is devised to study the impact of parameter uncertainty on wave propagation characteristics. The sensitivity analysis can be used to study how material choices affect the propagation characteristics, and to indicate which material parameters need to be identified accurately in order to achieve accurate fault localization. The analysis shows that the sensitivity of the propagation constant due to a change in the conductivity in the three metallic layers (the inner conductor, the intermediate lead shield, and the outer steel armor) is comparable to the sensitivity with respect to the permittivity of the insulating layer. Hence, proper modeling of the EM fields inside the metallic layers is crucial in the low-frequency regime of 0-100 kHz.

  • 23.
    Gustafsson, Stefan
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Nilsson, Börje
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Sjöberg, Mats
    ABB AB, Karlskrona, Sweden.
    Wave propagation characteristics and model uncertainties for HVDC power cables2015In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 30, no 6, p. 2527-2534Article in journal (Refereed)
    Abstract [en]

    This paper presents a stable and efficient fullwave cable model and a detailed study of the relatedmodel uncertainties regarding the wave propagation characteristics of very long HVDC power cables at low frequencies. The model can be used to predict the dispersion characteristics of the cable with respect to its electromagnetic parameters, or as an inverse problem to estimate some parameters of the cable (armour permeability, metal layer conductivities, temperature, length, etc.) based on measurements. The electromagnetic model is based on a magnetic frill generator that can be calibrated to the current measured at the input of the cable, and a layer recursive computation of the axial-symmetric fields. Measurements of pulse propagation on an 82 km long HVDC power cable over a bandwidth of 100 kHz have been used to validate the model. The main conclusion of the study is that the conductivity (and thus the temperature) of the conductor and the lead sheath are of utmost importance to achieve an accurate model. At the same time, some parameters are in principle insignificant regarding the dispersion characteristics in the low-frequency regime, such as the permittivity and the conductivity of the semi-conducting screens. The paper contains an investigation and a discussion on the electromagnetic properties of all layers of a typical HVDC power cable.

  • 24.
    Gustafsson, Stefan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nilsson, Börje
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    An electromagnetic dispersion model for HVDC Power Cables2012Conference paper (Refereed)
  • 25.
    Gustafsson, Stefan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nilsson, Börje
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Electromagnetic dispersion modeling and sensitivity analysis for HVDC power cables2012Report (Other academic)
    Abstract [en]

    This paper addresses electromagnetic wave propagation in High Voltage Direct Current (HVDC) power cables. An electromagnetic model, based on long (10 km or more) cables with a frequency range of 0 to 100 kHz, is derived. Relating the frequency to the propagation constant a dispersion relation is formulated using a recursive approach. The propagation constant is found numerically with normalized residue calculation. The paper is concluded with a sensitivity analysis of the propagation constant with respect to the electrical parameters εr (the real relative permittivity) and σ (the conductivity)

  • 26. Hashemzadeh, Parham
    et al.
    Kantaritzis, Panagiotis
    Liatsis, Panos
    Bayford, Richard
    Nordebo, Sven
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    A Cramer-Rao Bound Approach for Evaluating the Quality of Experimental Setups in Electrical Impedance Tomography2011In: Proceeding (723) Biomedical Engineering, 2011Conference paper (Refereed)
    Abstract [en]

    In this report, we propose the application of the Cramer Rao Lower Bound (CRLB) as a performance measure for optimal design of experimental setups in electrical impedance tomography. In particular, we focus on the optimum positioning of electrodes. Cramer Rao Bound is bounded from below by the inverse of the Fisher information matrix (FIM). FIM incorporates all aspects of the forward problem, statistical properties of the measurement noise, and multi-frequency data. We consider the application of CRB in both the deterministic as well as the Bayesian setting. We first present the CRB for the case of the unbiased estimator and then the Bayesian Cramer Rao Bound (BCRB) for the case of the biased estimator. All CRB computations are performed using a measured noise model from a clinical experiment.

  • 27.
    Ioannidis, Andreas
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Nilsson, Börje
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    A mathematical framework for propagation in an open cavity2013In: Proceeding of 2013 URSI International Symposium on Electromagnetic Theory (EMTS): International Conference Center HiroshimaHiroshima, Japan, May 20-24, 2013, IEEE Press, 2013, p. 1043-1046Conference paper (Refereed)
    Abstract [en]

    The purpose of this paper is to establish a formal mathematical framework for the electromagnetic wave propagation in an arbitrary cavity. The walls of the cavity are not assumed perfectly conducting and we use the transmission boundary conditions for the tangential fields. Our main tool is the Laplace transform. The focus here is on the modeling and detailed proofs or calculations are not provided.

  • 28.
    Ivanenko, Yevhen
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Gustafsson, Mats
    Lund University.
    Jonsson, B.L.G.
    KTH Royal Institute of Technology.
    Luger, Annemarie
    Stockholm University.
    Nilsson, Börje
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Toft, Joachim
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Passive approximation and optimization with B-splines2017Report (Other academic)
    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. 

  • 29.
    Ivanenko, Yevhen
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Approximation of dielectric spectroscopy data with Herglotz functions on the real line and convex optimization2016In: Proceedings of the  2016 18th International Conference on Electromagnetics in Advanced Applications, IEEE, 2016, p. 863-866Conference paper (Refereed)
    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. 

  • 30.
    Ivanenko, Yevhen
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Cylindrical multipole expansion for periodic sources with applications for three-phase power cables2016Conference paper (Other academic)
  • 31.
    Ivanenko, Yevhen
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Estimation of complex valued permeability of cable armour steel2016In: 2016 URSI International Symposium on Electromagnetic Theory (EMTS), IEEE Press, 2016Conference paper (Refereed)
    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.

  • 32.
    Ivanenko, Yevhen
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Estimation of electromagnetic parameters of cable steel2015In: Progress in Electromagnetics Research Symposium (PIERS), Prague, Czech Republic, 6-9 July 2015, Electromagnetics Academy , 2015, p. 1068-Conference paper (Other academic)
  • 33.
    Ivanenko, Yevhen
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Measurements and estimation of the complex valued permeability of magnetic steel2015Report (Other academic)
    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.

  • 34.
    Khodadad, Davood
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Mueller, Beat
    Swisstom AG, Switzerland.
    Waldmann, Andreas Daniel
    Swisstom AG, Switzerland.
    Yerworth, Rebecca
    University College London, UK.
    Becher, Tobias
    University Medical Centre Schleswig-Holstein, Germany.
    Frerichs, Inez
    University Medical Centre Schleswig-Holstein, Germany.
    Sophocleous, Louiza
    University of Cyprus, Cyprus.
    Kaam, Anton van
    Emma Children's Hospital, Academic Medical Center, Netherlands ; VU Medical Center, Netherlands.
    Miedema, Martijn
    Emma Children's Hospital, Academic Medical Center, Netherlands.
    Seifnaraghi, Nima
    Middlesex University, UK.
    Bayford, Richard H
    Middlesex University, UK.
    Optimized breath detection algorithm in electrical impedance tomography2018In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 39, no 9, article id 094001Article in journal (Refereed)
    Abstract [en]

    Objective: This paper defines a method for optimizing the breath delineation algorithms used in Electrical Impedance Tomography (EIT). In lung EIT the identification of the breath phases is central for generating tidal impedance variation images, subsequent data analysis and clinical evaluation. The optimisation of these algorithms is particularly important in neonatal care since the existing breath detectors developed for adults may give insufficient reliability in neonates due to their very irregular breathing pattern. Approach: Our approach is generic in the sense that it relies on the definition of a gold standard and the associated definition of detector sensitivity and specificity, an optimisation criterion and a set of detector parameters to be investigated. The gold standard has been defined by 11 clinicians with previous experience with EIT and the performance of our approach is described and validated using a neonatal EIT dataset acquired within the EU-funded CRADL project. Main results: Three different algorithms are proposed that are improving the breath detector performance by adding conditions on 1) maximum tidal breath rate obtained from zero-crossings of the EIT breathing signal, 2) minimum tidal impedance amplitude and 3) minimum tidal breath rate obtained from Time-Frequency (TF) analysis. As a baseline the zero crossing algorithm has been used with some default parameters based on the Swisstom EIT device. Significance: Based on the gold standard, the most crucial parameters of the proposed algorithms are optimised by using a simple exhaustive search and a weighted metric defined in connection with the Receiver Operating Characterics (ROC). This provides a practical way to achieve any desirable trade-off between the sensitivity and the specificity of the detectors.

  • 35.
    Khodadad, Davood
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Seifnaraghi, Nima
    The Burroughs, UK.
    Waldmann, Andreas D.
    Swisstom AG, Switzerland.
    Müller, Beat
    Swisstom AG, Switzerland.
    Bayford, Richard
    The Burroughs, UK.
    Breath detection using short-time Fourier transform analysis in electrical impedance tomography2017In: 2017 32nd General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2017, IEEE, 2017, , p. 3p. 1-3Conference paper (Refereed)
    Abstract [en]

    Spectral analysis based on short-time Fourier transform (STFT) using Kaiser window is proposed to examine the frequency components of neonates EIT data. In this way, a simultaneous spatial-time-frequency analysis is achieved.

  • 36.
    Khodadad, Davood
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Seifnaraghi, Nima
    Middlesex University, UK.
    Yerworth, Rebecca
    University College London, UK.
    Waldmann, Andreas D.
    Swisstom AG. Switzerland.
    Muller, Beat
    Swisstom AG, Switzerland.
    Frerichs, Inez
    University Medical Centre Schleswig-Holstein, Germany.
    Kaam, Anton van
    Emma Children's Hospital, Academic Medical Center, Netherlands.
    Miedema, Martijn
    Emma Children's Hospital, Academic Medical Center, Netherlands.
    Bayford, Richard
    Middlesex University, UK.
    The Value of Phase Angle in Electrical Impedance Tomography Breath Detection2018In: Progress In Electromagnetics Research Symposium 2018, 2018Conference paper (Refereed)
  • 37.
    Khrennikov, Andrei
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nilsson, Börje
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Classical signal model reproducing quantum probabilities for single and coincidence detections2012In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 361, article id 012030Article in journal (Refereed)
    Abstract [en]

    We present a simple classical (random) signal model reproducing Born's rule. The crucial point of our approach is that the presence of detector's threshold and calibration procedure have to be treated not as simply experimental technicalities, but as the basic counterparts of the theoretical model. We call this approach threshold signal detection model (TSD). The experiment on coincidence detection which was done by Grangier in 1986 [22] played a crucial role in rejection of (semi-)classical field models in favour of quantum mechanics (QM): impossibility to resolve the wave-particle duality in favour of a purely wavemodel. QM predicts that the relative probability of coincidence detection, the coefficient g((2)) (0); is zero (for one photon states), but in (semi-) classicalmodels g((2)) (0) >= 1 : In TSD the coefficient g((2)) (0) decreases as 1/epsilon(2)(d); where epsilon(d) > 0 is the detection threshold. Hence, by increasing this threshold an experimenter can make the coefficient g((2)) (0) essentially less than 1. The TSD-prediction can be tested experimentally in new Grangier type experiments presenting a detailed monitoring of dependence of the coefficient g((2)) (0) on the detection threshold. Structurally our model has some similarity with the prequantum model of Grossing et al. Subquantum stochasticity is composed of the two counterparts: a stationary process in the space of internal degrees of freedom and the random walk type motion describing the temporal dynamics.

  • 38.
    Khrennikov, Andrei
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nilsson, Börje
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    On an experimental test of prequantum theory of classical random fields: an estimate from above of the coefficient of second-order coherence2012In: International Journal of Quantum Information, ISSN 0219-7499, Vol. 10, no 8, p. Article ID: 1241014-Article in journal (Refereed)
    Abstract [en]

    We show that quantum probabilities for photon detection can be reproduced by a model in which classical random fields interact with detectors of the threshold type. This approach is applied to the old problem of distinguishing classical and quantum light sources with the aid of the coefficient of second-order coherence g(2) (0) ( the problem of "existence of photon"). In our classical random field model, we obtain an estimate of this coefficient implying that it becomes strictly less than one for sufficiently small value of parameter is an element of = (epsilon) over bar/epsilon(d), where (epsilon) over bar (pulse) is the average energy of pulses (photons) emitted by a source and epsilon(d) is the detection threshold. This prediction can in principle be tested experimentally. Thus in the presented model experimental technicalities (such as e. g. the detection thresholds) are lifted to the level of the fundamental entities of theory.

  • 39.
    Khrennikov, Andrei
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nilsson, Börje
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Quantization of propagating modes in optical fibres2012In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 85, p. Article ID: 065404-Article in journal (Refereed)
    Abstract [en]

    The electromagnetic fields of a single optic fibre mode are quantized based on the observationthat these fields can be derived from a scalar harmonic oscillator function depending on onlytime and the axial wavenumber. Asymptotic results for both the one-photon probabilitydensity and two-photon correlation density functions within the forward light cone arepresented, showing an algebraic decay for large times or distances. This algebraic decay,increasing the uncertainty in the arrival time of the photons, also remains in the presence ofdispersion shift, in qualitative agreement with experimental results. Also presented are explicitformulae to be used in parameter studies to optimize quantum optic fibre communications.

  • 40.
    Khrennikov, Andrei
    et al.
    Linnaeus University, Faculty of Engineering and Technology, Department of Mathematics.
    Nilsson, Börje
    Linnaeus University, Faculty of Engineering and Technology, Department of Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Engineering and Technology, Department of Physics and Electrical Engineering.
    Quantum rule for detection probability from Brownian motion in the space of classical fields2013In: Theoretical and mathematical physics, ISSN 0040-5779, E-ISSN 1573-9333, Vol. 174, no 2, p. 298-306Article in journal (Refereed)
    Abstract [en]

    We obtain Born's rule from the classical theory of random waves in combination with the use of thresholdtype detectors. We consider a model of classical random waves interacting with classical detectors and reproducing Born's rule. We do not discuss complicated interpretational problems of quantum foundations. The reader can select between the "weak interpretation," the classical mathematical simulation of the quantum measurement process, and the "strong interpretation," the classical wave model of the real quantum (in fact, subquantum) phenomena.

  • 41.
    Khrennikov, Andrei
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nilsson, Börje
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Volovich, I. V.
    Distance Dependence of Entangled Photons in Waveguides2012In: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616, Vol. 1424, p. 262-269Article in journal (Refereed)
    Abstract [en]

    The distance dependence of the probability of observing two photons in a waveguide is investigated and the Glauber correlation functions of the entangled photons are considered. First the case of a hollow waveguide with modal dispersion is treated in detail: the spatial and temporal dependence of the correlation functions is evaluated and the distance dependence of the probability of observing two photons upper bounds and asymptotic expressions valid for large distances are derived. Second the generalization to a real fibre with both material and modal dispersion, allowing dispersion shift, is discussed.

  • 42.
    Khrennikov, Andrei
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nilsson, Börje
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Volovich, Igor
    Russian Academy of Sciences.
    On the quantization of the electromagnetic field of a layered dielectric waveguide2012In: QUANTUM THEORY: RECONSIDERATION OF FOUNDATIONS 6, 2012, p. 285-299Conference paper (Refereed)
    Abstract [en]

    This paper gives a detailed derivation of the classical electromagnetic modes of a layered circularly symmetrical dielectric waveguide. The corresponding Hamilton function is derived by using suitable canonical observables and the standard analogy to the classical harmonic oscillator. The derivation is generic in the sense that it can be used as an "algorithm" to compute the electromagnetic field of the waveguide. The associated Hamilton operator can then be obtained by using the standard quantization procedure where the canonical observables are replaced by the corresponding operators i.e., the creation and the annihilation operators of the photon (or equivalently, the position and the momentum operators of the harmonic oscillator) and by taking the appropriate commutation relations into account.

  • 43.
    Khrennikov, Andrei
    et al.
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Nilsson, Börje
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Volovich, Igor
    Russian Acad Sci.
    Photon Flux and Distance from the Source: Consequences for Quantum Communication2014In: Foundations of physics, ISSN 0015-9018, E-ISSN 1572-9516, Vol. 44, no 4, p. 389-405Article in journal (Refereed)
    Abstract [en]

    The paper explores the fundamental physical principles of quantum mechanics (in fact, quantum field theory) that limit the bit rate for long distances and examines the assumption used in this exploration that losses can be ignored. Propagation of photons in optical fibers is modelled using methods of quantum electrodynamics. We define the "photon duration" as the standard deviation of the photon arrival time; we find its asymptotics for long distances and then obtain the main result of the paper: the linear dependence of photon duration on the distance when losses can be ignored. This effect puts the limit to joint increasing of the photon flux and the distance from the source and it has consequences for quantum communication. Once quantum communication develops into a real technology (including essential decrease of losses in optical fibres), it would be appealing to engineers to increase both the photon flux and the distance. And here our "photon flux/distance effect" has to be taken into account. This effect also may set an additional constraint to the performance of a loophole free test of Bell's type-to close jointly the detection and locality loopholes.

  • 44. Lundbäck, Jonas
    et al.
    Nordebo, Sven
    FMCW radar for fault localization on power lines2005In: Radiovetenskaplig konferens RVK, Linköping, Sweden, June 2005., 2005Conference paper (Refereed)
  • 45. Lundbäck, Jonas
    et al.
    Nordebo, Sven
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Biro, Thomas
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    A Digital Directional Coupler with Applications to Partial Discharge Measurements2008In: IEEE Transactions on Instrumentation and Measurements, ISSN 0018-9456, Vol. 57, no 11, p. 2561-2567Article in journal (Refereed)
    Abstract [en]

    This paper presents a digital directional coupler (DDC) that separates forward- and backward-traveling waves on a transmission line. Based on two independent wideband measurements of voltage and current and on frequency-domain digital wave splitting using a fast Fourier transform (FFT), the DDC is a versatile device for direction separation. A practical procedure is described for the calibration of the digital processor with respect to the particular transmission line and the voltage and current sensors that are being used. As an experiment, a DDC was designed and implemented using low-cost wideband sensors and was installed with medium-voltage equipment in a power distribution station. Partial discharge (PD) measurements were conducted on cross-linked polyethylene (XLPE)-insulated power cables to illustrate the directional separation capabilities of the DDC.

  • 46.
    Lundbäck, Jonas
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Nordebo, Sven
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Gustafsson, Mats
    A Generic Electromagnetic Model for DOA Estimation using Arbitrary Multiport Antennas2006In: IEEE International Symposium on Antennas and Propagation, 2006, p. 2549-2552Conference paper (Refereed)
    Abstract [en]

    A mathematical framework is introduced for optimization of antenna near-field imaging problems, based on the multipole expansion of the electromagnetic field, the Fisher information to quantify the quality of data and use of modern interior point convex optimization techniques. We consider the general problem of optimizing the measurement sensor allocation for parameter estimation in distributed systems, and in particular the problem of optimizing the measurement set-up for antenna near-field estimation. As an application example for antenna near-field imaging, we consider a relevant measurement set-up using cylindrical probing coordinates. The convex optimization problem is examined using duality theory, and it is shown that several structural properties of the optimal measurement problem can be exploited in developing an efficient interior point optimization method. In particular, we show that the cylindrical measurement set-up yields a Fisher information matrix with block diagonal structure, a feature which can be directly exploited in the optimization algorithm by reducing the number of dual decision variables.

  • 47.
    Nilsson, Börje
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Cinar, Gökhan
    Özge, Cinar
    Nordebo, Sven
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Asymptotic Methods for Long Distance Monitoring of Power Cables2012Conference paper (Refereed)
  • 48.
    Nilsson, Börje
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Fishman, LoisMDF International, USA.Karlsson, AndersElektro- och informationsteknik, LTH.Nordebo, SvenVäxjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Mathematical Modeling of Wave phenomena.: 3rd Conference on Mathematical Modelling of Wave Phenomena, Växjö, Sweden, 9 – 13 June 20082009Conference proceedings (editor) (Other academic)
    Abstract [en]

     

     

    This conference illuminates and benefits from relations between different types of waves, i.e., quantum physics methods in classical wave modeling. The proceedings are intended for researchers and graduate students in fundamental as well as applied sciences. The preface classifies and summarizes the conference giving relations between the papers.

     

     

     

     

     

     

  • 49.
    Nilsson, Börje
    et al.
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Ioannidis, Andreas
    Hellenic Naval Academy, Greece.
    Ivanenko, Yevhen
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Nordebo, Sven
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    On absence of sources at infinity and uniqueness for waveguide solutions2016In: Proceedings of the 2016 18th International Conference on Electromagnetics in Advanced Applications, ICEEA 2016, IEEE Press, 2016, p. 780-783Conference paper (Refereed)
    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.

  • 50.
    Nilsson, Börje
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Nordebo, Sven
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Gustafsson, Stefan
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Ioannidis, Andreas
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Long distance source localization in waveguides with complicated structure2012In: 2012 International Conference on Mathematical Methods in Electromagnetic Theory (MMET), Los Almitos: IEEE, 2012, p. 415-418Conference paper (Other academic)
    Abstract [en]

    With the purpose of source localization in high voltage direct current submarine power cables general layered waveguide models are investigated. It is concludes that the non-discrete modes can usually be ignored in comparison with the least attenuated discrete mode. Only a finite number of discrete modes are of importance for a band limited signal. Accurate analytical expressions are derived in the time domain for both discrete and non-discrete electromagnetic waveguide modes for large distances together with an error analysis.

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