ANNUAL REPORT 2008 ELECTROMAGNETIC ENGINEERING

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ANNUAL REPORT 2008 ELECTROMAGNETIC ENGINEERING

KTH Electrical Engineering School

Electromagnetic Engineering Division Teknikringen 33

SE-100 44 Stockholm

www.etk.ee.kth.se

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ELECTROMAGNETIC ENGINEERING ANNUAL REPORT 2008

CONTENTS Highlights 1 General resources

1.1 Personnel 1.2 Economy 1.3 Office facilities and laboratories

2 Undergraduate and continuing education

2.1 Undergraduate courses 2.2 Undergraduate theses 2.3 Continuing education

3 Graduate education

3.1 Graduate courses 3.2 Graduate theses

4 Research activities

4.1 Electromagnetic theory 4.2 Novel electromagnetic metamaterials and photonics 4.3 Electromagnetic compatibility 4.4 Electrotechnical modeling 4.5 Antenna theory and design 4.6 Insulation diagnostics 4.7 Reliability centered asset management (RCAM)

5 Publications and reports

5.1 Ph.D. theses 5.2 Licentiate theses 5.3 Master theses 5.4 Books 5.5 Articles in journals 5.6 Conference proceedings 5.7 Reports 5.8 Miscellaneous

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6 Conferences, courses and visits

7 Seminars and lectures 7.1 Seminars and lectures at KTH 7.2 Seminars given outside KTH

8 Other activities 8.1 National assignments 8.2 International assignments 8.3 Mobility

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Highlights The scientific and technical activities of the Electromagnetic Engineering division include basic electromagnetic theory and the physical and technical fundamentals for design of electrical devices. A brief summary of the most important events during 2008 is given below o Rajeev Thottappillil was appointed professor in Electric power engineering and

design from September 2008 and took over as department head from October 2008. o A research group in Electromagnetic compatibility (EMC) was formed including

four Ph.D. students to be shifted from Uppsala University. o Lina Bertling was promoted docent in electrical systems. o Lina Bertling became Research Director at Svenska Kraftnät from June 1, 2008, and

was appointed professor in sustainable electric power systems at Chalmers in November 2008 (position to be taken from January 2009).

o Six Ph.D. theses was presented Patrik Hilber on April 18, 2008 Tommie Lindquist on April 25, 2008 Cecilia Forssén, on June 4, 2008 Jörgen Ramprecht on June 5, 2008 Jun Song on June 11, 2008 Mohsen Torabzadeh-Tari on December 15, 2008

o One Licentiate thesis was presented Carl Johan Wallnerström on May 15, 2008

o Undergraduate production amounted to 54.6 full time students o 14 Master theses projects were completed. o Sabina Karlsson was awarded price for the best master thesis 2007 on maintenance. o 4 new Ph.D. students were recruited. o Two new major research projects were granted, on electromagnetic compatibility by

Banverket and on small MIMO antennas system by VINNOA.

1 General resources 1.1 Personnel Electromagnetic engineering consists of the following individuals. E-mail addresses are composed as firstname.familyname@ee.kth.se: o Roland Eriksson Professor o Rajeev Thottappillil Professor, from September 2008 o Göran Engdahl Professor o Sailing He Professor o Staffan Ström Professor em o Lars Jonsson Associate Professor o Gunnar Larson Associate Professor

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o Martin Norgren Associate Professor o Gunnar Pettersson Associate Professor em o Lina Bertling Associate Professor o Hans Edin Assistant Professor o Peter Fuks Senior Researcher o Stefan Arnborg Guest researcher (20%) o Dierk Borrmann Guest researcher (20%) o Daniel Månsson Guest researcher (from October 2008) o Michael Patriksson Guest researcher (5%) o Gulli Frohmader Administrator o Lars Austrin Ph.D. student o François Besnard " " (from July 07) o Valentinas Dubickas " " o Andres Ellgart " " o Cecilia Forssén " " (until June 2008) o Patrik Hilber " " (researcher from May 2008) o Xin Hu " " o Siti Fatima Jainal " " (from January 2009) o Kelin Jia " " (from October 2008) o Nadja Jäverberg " " o Andrea Lang " " (until November 2008) o Xuan Li " " o Tommie Lindquist " " (until June 2008) o Ziya Mazloom " " (from January 2009) o Surajit Midya " " (from January 2009) o Alireza Motevasselian " " o Julia Nilsson " " o Jörgen Ramprecht " " (until July 2008) o David Ribbenfjärd " " o Johan Setreus " " o Jianqi Shen " " o Jun Song " " (until June 2008) o Hanif Tavakoli " " o Nathaniel Taylor " " o Mohsen Torabzadeh " " o Carl Johan Wallnerström " o Kristian Winter " " Rajeev Thottappillil took over as head of the department from October 2008. Roland Eriksson, previous head of department retires in January 2009. 1.2 Economy The turnover of division was 23.2 MSEK. The grants were supplied by KTH (12.5 MSEK) and by external sponsors (10.7 MSEK).

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1.3 Office facilities and laboratories The division has the following facilities: - high-voltage laboratory including a multitest set for 2x200 kV dc, 2x100 kV AC

and 400 kV impulse. - EMC laboratory (under erection). - laboratory for static and dynamic measurements of magnetic materials

characteristics - laboratory for characterization of insulating materials by measurements of dielectric

response and partial discharges - screened room for partial discharge mesurements etc. - antenna research laboratory. - various computers with software for dynamic simulations, and transient analysis

2 Undergraduate and continuing education 2.1 Undergraduate courses The undergraduate courses given by Electromagnetic Engineering are: EI1100 Electrical Circuit Analysis (credit = 7,5) Peter Fuks Lectures 24h, Tutorials 30h, Laboration 4h Ohm’s and Kirchhoff’s laws. Systems of equations. Transients. Complex representation of currents and tensions. Impedance and admittance. Complex power and impedance matching. Filters. Mutual inductive coupling. Transistors and operational amplifiers

EI1101 Applied Electronics (credit = 1,5) Peter Fuks Lectures 6h, Laborations 8h , Seminaries 4h

The course gives a “hands on” experience of design of electronic equipenent. The dominant part is a project during which the student will build a working prototype, solve EMC problems and design a scheme for fault finding. Syllabus: Passive and active componentsr. Tolerances. Frequency, power och tensions limitations. Discrepancies from simple models. Analog och digital building blocks. EMC. Security. Electronic design. Conventions. Prited circuits. Soldering. Fault finding. EI1200 Electromagnetic Theory (credit = 7,5) Gunnar Larson Lectures 37h, Tutorials 36h Electrostatics: Coulomb's law. Electric lines of force. Evaluation of electric field and potential in vacuum and with conducting and dielectric materials. Practical electrostatic

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problems. Energy and forces in electrostatic systems. Boundary-value problems. Method of images. Direct current: Ohm's and Joule's laws. The continuity equation. Boundary-value problems. Static magnetic fields: Biot-Savart's and Ampere's laws. Fields in magnetic materials. Magnetic circuits. EI210 Wave propagation and antennas (credit = 7,5) Gunnar Larson Lectures 37h, Tutorials 36h Electromagnetic induction: Transformation of electric and magnetic fields between systems with uniform velocity. Faraday's law. Mutual and self-induction. Energy and forces in static and quasi-stationary fields. Maxwell's equations: Applications of Maxwell's equations. Plane wave propagation and reflection. Radiation and reception of electromagnetic waves. Skin effect. Transmission lines. Antennas and radiating systems. EI1240 Electromagnetic Theory F (credit = 9) Martin Norgren Lectures 51h, Tutorials 50h Part 1: Static fields Electrostatics: Coulomb's law and Gauss’ law. Electric lines of force. Evaluation of electric field and potential in vacuum and with conducting and dielectric materials. Practical electrostatic problems. Energy and forces in electrostatic systems. Boundary-value problems. Method of images. Static magnetic fields: Biot-Savart's and Ampere's laws. Fields in magnetic materials.

Part 2: Time-dependent fields Electromagnetic induction. Faraday's law. Mutual and self-induction. Energy and forces in static and quasi-stationary fields. Maxwell's equations. Conservation laws. Plane waves: propagation, reflection and polarisation. Waveguides. Radiation and reception of electromagnetic waves Transformation of electric and magnetic fields between systems with uniform velocity.

EI1260 Electromagnetic Theory CL, introductory course (credit = 6) Martin Norgren Lectures 37h, Tutorials 36h

Coulomb's law and Gauss’ law. Electric lines of force. Evaluation of electric field and potential in vacuum and with materials. Energy and forces in electrostatic systems. Static magnetic fields: Biot-Savart's and Ampere's laws. Fields in magnetic materials. Electromagnetic induction. Faraday's law. Mutual and self-induction. Maxwell's equations. Plane waves: propagation, reflection and polarisation. EI2400 Applied Antenna Theory (credit = 7,5) Gunnar Larson Lessons 30h, Laboration 14h The course takes a “hands on” approach. Projects and laborations are the principal part. The student will design different types of antennas, build them and measure their properties. The lectures discuss different antenna types such as wire antennas, aperture antennas, broadband antennas, small antennas and array, antenna feeds, antenna synthesis, system aspects on “transmitting – to – receiver” problems, propagation, numerical methods and different aspects of antenna measurements.

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EI2405 Classical Electrodynamics (credit = 7,5) Martin Norgren Lessons 60h Green's functions to Poisson equation. Orthogonal function systems. Electrostatic and magnetostatic boundary value problems. Multipole expansions of electrostatic and magnetostatic fields. Maxwell’s equations, potentials and Gauge transformations. Green functions for the wave equation. Retarded fields from continuous sources and point charges. Conservation laws for energy, momentum and angular momentum. Transformation properties of the fields under rotation, spatial inversion and time-reversal. Polarisation, reflection and transmission of plane waves. Lorentz transformation and 4-vector quantities. The field tensor and the covariant formulation of Maxwell’s equations. EI2410 Field Theory for Guided Waves (credit = 7,5) Martin Norgren Lessons 50h, Project supervision 8h, Study visit 4h Plane waves. Decomposition of fields and Maxwell’s equations. Metallic waveguides: TM-, TE- and TEM-modes; mode orthogonality; power transport; excitation; mode-matching; attenuation. Resonance cavities: attenuation and Q-value. Dielectric waveguides: TE-, TM-, EH, and HE-modes in fibers. Multiconductor transmission lines: quasi-TEM modes; power transport; mode-scattering. EI2420 Electromagnetic Wave Propagation (credit = 7,5) Lars Jonsson Lessons 56h Differential equations for the electromagnetic fields. Integral representation in finite and infinite domains. Radiation conditions. Electric and magnetic equivalent surface currents. Applications to reflector antennas. Approximate methods at high frequencies: Geometrical and physical optics. Electromagnetic multipole fields. Application to scattering from a sphere. Scattering cross section. Wave propagation from dipoles above the ground. Methods of stationary phase and steepest descent. The Null Field Method. Integral equation method for electromagnetic boundary value problems. EI2430 High-voltage engineering (credit = 7,5) Hans Edin Lectures 26h, Laboratory 12 h, Project works 50h.

The course shall develop the participants' ability to solve problems related to high-voltage design. Project works are conducted on high-voltage measuring and testing technique and insulation diagnosis where the problems are studied experimentally and with computer-based tools. EI2333, EI2433 Electrotechnical modeling (credit = 7,5) Göran Engdahl Lectures 34h, numerical workshops 28 h, 7 Project works.

The course treats models for electrotechnical systems and components and how these models can be used for solving electrotechnical design problems and understanding of electrophysical phenomena. The course includes a number of individual tasks where the problem shall be formulated and a model developed for solving the problem.

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EI2440 Electrotechnical design (credit = 7,5) Göran Engdahl Lectures 32 h, Tutorials 28H, Laboratory 8 h, 4 Project works

The course provides knowledge on how electrical, magnetic, mechanical and thermal problems are dealt with in design of electrical equipment and training of the ability to solve related design problems. The course gives the basics for solving these problems analytically and in project works examples of design problems on fields and dynamic systems treated by computer-based tools. EI2450 Reliability Assessment of Power Systems (credit = 6) Lina Bertling Lectures 60 h including computer labs, and project work.

This course treats reliability theory applied for electric power systems. The course give knowledge in using reliability assessment as a tool for decision support for; planning, operation and maintenance of the electric power system. The course is concentrated to 9 full lecture days and a final seminar, and involves work with an own project. The course is run together with the further education course EI2450V. 2.2 Undergraduate theses Undergraduate theses are carried of within the following fields:

Electromagnetic field theory Electrotechnical modeling High-Voltage engineering Reliability analysis for power systems

During the year 14 master theses projects have been carried out for achievement of the university degree 'civilingenjör' or Master's degree, see publication list.

2.3 Continuing education EI2450V Reliability Assessment of Power Systems (credits = 6) Lina Bertling This is an advanced course for academics in the industry. The course is a condensed version of the further education course EI2450, with the same name, and has the same content, course goal and examination form. The course is given on request. 3 Graduate education 3.1 Graduate courses The division has two research subjects. Electromagnetic theory and Electrical systems. 3.1.1 Graduate courses, Electromagnetic theory

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F2H5051 Basic Electromagnetic Theory (credit=7-23) The goal of this course is to provide a thorough knowledge of the structure of the basic equations of classical electromagnetism, as well as of the basic methods for solving these equations. F2H5052 Analytic methods in electromagnetic field theory (credit=7-38) The goal of this course is to give a more comprehensive knowledge concerning modern mathematical and computational methods relevant for electromagnetic field theory. Included are Green’s function techniques, integral equations, asymptotic methods, perturbation methods, as they apply to both the differential and integral equations formulation of electromagnetic field problems. F2H5053 Electromagnetic fields in inhomogeneous media (credit=7-23) The goal of this course is to provide knowledge concerning methods for treating electromagnetic fields in inhomogeneous media characterized by complicated material properties and/or geometrical form. F2H5054 Numerical methods in electromagnetic field theory (credit=7-30) The goal of this course is to provide knowledge concerning modern computational methods in electromagnetic field theory and to provide a deeper knowledge concerning those methods which are relevant for the thesis work. F2H5055 Antenna theory and design (credit=7-30) The goal of this course is to provide knowledge concerning analytic and numerical methods that are relevant for modern antenna technology. 3.1.2 Graduate courses Electrical systems F2C5109 Graduate course in electric systems (credit=5-20) The goal of this course is to provide knowledge on power system fundamentals. F2C5139 Graduate course in electrotechnical design (credit=5-20) This course aim is to provide knowledge on electrotechnical design principles and fundamentals relevant for the specific research task. The course can be tailor made for the Ph.D. student. F2C5107 Complementary graduate course in electrical systems (credit=5-20) This course aims at providing knowledge complementary to the research subject such as scientific methods, writing of scientific papers, etc.

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F2C5060 Maintenance Management of Power Systems (credit = 7.5), Lina Bertling This is a Ph.D. course for students at the Electrical engineering program or other related topics. The course covers the topic of maintenance management divided into the four themes of: (1) Reliability data assessment and reliability modelling and assessment, (2) Reliability centred maintenance for maintenance optimization, (3) Condition monitoring and diagnostics methods and (4) Computer tools supporting techniques for maintenance planning. The course includes specialist lectures and own student work with an individual task. The course is given in cooperation with Helsinki University of Technology (TKK), It was given at KTH in 2007 and is planned again for 2009. F2C5061 Mathematical optimization models for maintenance management (credit = 6), Lina Bertling This is a Ph.D. course for students at the Electrical engineering program. The course aims to give an overview of an important type of mathematical models for maintenance optimization and the associated mathematical machinery – optimization theory and algorithms. The course consists of theoretical lecture series, presentation of a practical study of a maintenance optimization model, and includes a own project assignment. The course was given for the first time in 2006 in collaboration with Applied Mathematics at Chalmers. 3.2 Graduate theses Patrik Hilber defended his doctoral thesis: Maintenance Optimization for Power Distribution Systems, April 18, 2008. Opponent Professor Lalit Goel, Nanyang Technological University, Singapore. The thesis was supervised by Lina Bertling and Roland Eriksson. Tommie Lindquist defended his doctoral thesis: On reliability and maintenance modelling of ageing equipment in electric power systems, April 25, 2008. Opponent Professor George Anders, Professor University of Toronto, Canada. The thesis was supervised by Lina Bertling and Roland Eriksson. Carl Johan Wallnerström presented his licentiate thesis: On Risk Management of Electrical Distribution Systems and the Impact of Regulations, May 15, 2008. Opponent Professor Kjell Sand, SINTEF, Norway. The thesis was supervised by Lina Bertling and Roland Eriksson. Cecilia Forssén presented her doctoral thesis: Modelling of cavity partial discharges at variable applied frequency, June 4, 2008: Opponent Assoc. Prof. Peter Morshuis, Delft Univeristy of Technology, The Netherlands. The thesis was supervised by Hans Edin Jörgen Ramprecht defended his doctoral thesis: Electromagnetic Waves in Media with Ferromagnetic Losses, June 5, 2008. Opponent Prof. Constantin Simovski, Department of

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Radio Science and Engineering, Helsinki University of Technology, Finland. The thesis was supervised by Martin Norgren. Jun Song defended his doctoral thesis: "Electromagnetic simulation and design of etched diffraction grating demultiplexers", June 11, 2008. Opponent Prof. Dries Van Thourhout, Ghent University, Belgium. The thesis was supervised by Sailing He. Mohsen Torabzadeh-Tari presented his Ph. D. thesis: Dimensioning tools of MEA actuator systems, including modeling, analysis and technology comparison, December 2008. Opponent: Ass. Prof. Hans Bernhoff, Uppsala University, Uppsala, Sweden. The thesis was supervised by Göran Engdahl.

4 Research activities The main part of the research aims at developing theory, methods and models for the design and application of electrical components and systems for electric power and telecommunication. Most of the work is carried out in interaction with industry or is inspired by problems in real apparatuses. The research is divided into six programs - Electromagnetic theory - Metamaterials and optoelectronics - Electromagnetic compatibility - Electrotechnical modelling - Antenna theory and design

- Insulation diagnostics

- Reliability centered asset management (RCAM) 4.1 Electromagnetic theory The research group consists of:

• Sailing He (Professor) • Lars Jonsson (Associate professor) • Martin Norgren (Associate professor • Jörgen Ramprecht (Ph.D. student) • Staffan Ström (Prof. em.)

The research is focused on the basic macroscopic electromagnetic laws as they apply to the generation and propagation of electromagnetic effects in vacuum, in material media, and in

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all the various devices that may be constructed to enhance, control, and utilize such effects. Thus the use and further development of all the methods - analytic, numerical, and also experimental - which are relevant for such an endeavour, are of prime interest to us. Somewhat more specifically, the main thrust of our research effort is in the area of propagation and scattering of electromagnetic waves. Progress in this area is crucial to the development of the various tools that are used so frequently in what is broadly referred to as the information society. This trend in modern society makes us increasingly dependent upon electromagnetic waves as carriers of information. One of our main areas of research is direct and inverse scattering problems, both in the time and the frequency domain. In a direct scattering or propagation problem one considers the problem of determining the behaviour of an electromagnetic wave as it encounters an object or medium with known electromagnetic properties. In an inverse problem on the other hand, one analyses the way in which an electromagnetic wave has changed after it has passed through an unknown medium, and from this information one tries to infer the elec-tromagnetic properties of the medium. The proper understanding of electromagnetic information gathering devices (such as sensors) typically requires that one is able to solve, to some degree, a problem of the inverse type. Furthermore, design problems have much in common with inverse problems. The theoretical work ranges from studies of basic mathematical properties to numerical implementation of models relevant for specific applications. Non-linear effects are of great importance in many electromagnetic contexts, particularly in the context of high speed transmission over optical fibers. Progress in the theory of soliton propagation in such systems is then of obvious interest and the Division has recently become involved in basic research in that area. In addition to the greater mathematical understanding of nonlinear effects, such as uniqueness, well-posedness, blowups and asymptotics of the a number of nonlinear equations, we add physical understanding of complex nonlinear phenomena, both in electromagnetics as well as in other areas of physics. Dynamics and effective equations of several types of solitary waves has been the main focus for the last years. An increased focus on selected electromagnetic applications is foreseen 4.1.1 Small MIMO antennas system and assessment of the scattering limit HE, Sailing (professor, Ph.D.) JONSSON, Lars (associate professor, Ph.D.) In August 2008 we started a joint SINO-Swedish project under VINOVA with the title: “Access technologies: multiple access, multiple users, multiple distributed antenna systems” jointly between the EIT-group at LTH and the S3 and ETK groups at KTH. The project aims towards studies of future communication technologies. The department will study switchable Multiple-Input Multiple-Output (MIMO) Smart Antenna System, particularly the small antennas part and its analysis. On one hand, we want our antenna system to be compact, in particularly for a mobile terminal. On the other hand, the minimum spacing between the antennas required for sufficient low correlation between fading signals needs to be ensured. Therefore, design of small antennas and

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analysis of the coupling among antenna elements are important in order to make this antenna system practically useful. The size of antenna system will be reduced and different polarizations will be utilized to obtain sufficient low correlation between fading signals. For example, we can mount antenna elements (e.g. patch antennas) on the top surface and the four side surfaces of a cubic. Each antenna will be fed by two ports so that two orthogonal modes of polarization can be excited, which give low correlation of received signals. The same idea can be generalized for other cases when the total number of antennas is different and extended to antenna array for MIMO base stations. We will analyze the effects of polarizations, frequency bands, number of antennas, coupling and correlation on the overall performance in different surrounding environments. The department will also derive methods to assess to assess and utilize fundamental limits in the development of communication technologies. Recent progress has been made in scattering limits for small devices (Chu’s limit), on which our approach is based. Another object of study here is the use of time-reversal techniques in communication. (sponsored by Vinnova) 4.1.2 Dynamics of nonlinear equations JONSSON, Lars (associate professor, Ph.D.) Since 2002, Lars Jonsson, together with I. M. Sigal, J. Fröhlich and S. Gustafson and others has jointly been working on the dynamics of nonlinear Hamiltonian systems, nonlinear evolution equations like: Schrödinger equations (NLS), Hartree equations and semi-relativistic Hartree equations, and the Bogolubov-Hartree-Fock equation. We are interested in determining properties such as the dynamic behavior of the solutions, and conditions for global well posedness and blowup. The first results was determination how solutions which initial are close to a (free) solitary wave behaves under the perturbation of a slowly varying bounded, smooth potential. This was first done for the NLS equation. The result of this work is now published in Comm., Math. Phys. 250(3) pp.613–642, 2004. The result states that for long times, the solitary wave's position follows Newton's second law. This result was later improved to include confining potentials and longer times; the result is published in Annales Henri Poincare, 7(4) 621–660, 2006. Similarly L. Jonsson together with S. Dejak studied similar questions for the Korteweg-de Vries and the results have now appeared in J. Math. Phys 47, 072703 pp. 1–16, 2006. As a continuation of this project since 2006 extension towards the semi-relativistic Hartree equation resulting in two papers, (Jonsson, Fröhlich, Lenzmann: Boson stars as solitary waves. Commun. Math. Phys., 274(1):1–30, 2007, and Effective dynamics for boson stars. Nonlinearity, 20:1031–1075, 2007.). The first of these works treat the existence of ground states (solitons). The second of these papers extend the above works for NLS to the pseudo-relativistic Hartree equation, with modulation equations for solutions close to a soliton. This equation is a model for Boson stars, and the external potential models the influence of the external gravitational field (e.g. from other stars). The result in Nonlinearity on the dynamics required an assumption, which was numerically

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shown to be true in “The kernel condition of a linearized pseudo-relativistic Hartree equation, a numerical approach” which has been accepted to AIP Conference Proceedings: Mathematical Modeling of Wave Phenomena. The most recent result in this series of result is a result on Bogolubov-Hartree-Fock Mean Field Theory with Attractive Interactions. 4.1.3 Design of radar absorbers using magnetic materials RAMPRECHT, Jörgen (Ph.D. student) NORGREN Martin (associate professor, Ph.D.) This project was finished by June 2008, after Jörgen Ramprecht defended his PhD thesis. The final results are summarised in below. A magnetized thin layer mounted on a PEC surface has been considered as an alternative for an absorbing layer for radar cross section reduction. The magnetic material is modeled with the Landau-Lifshitz-Gilbert equation, with a lateral static magnetization having a periodic variation along one lateral direction. The scattering problem has been solved by means of an expansion into Floquet-modes, a propagator formalism and wave-splitting. Numerical results indicate that for parameter values close to the typical values for ferro- or ferrimagnetic media, reflection coefficients below -20 dB can be achieved for the fundamental mode over the frequency range 1-4 GHz, for both polarizations. It was found that the periodicity of the medium makes the reflection properties for the fundamental mode almost independent of the azimuthal direction of incidence, for both normally and obliquely incident waves. We have addressed some of the problems involved in homogenization of a composite material built from ferromagnetic inclusions in a nonmagnetic background material. The small signal permeability for a ferromagnetic spherical particle has been combined with a homogenization formula to give an effective permeability for the composite material. The composite material inherits the gyrotropic structure and resonant behavior of the single particle. The resonance frequency of the composite material was found to be independent of the volume fraction, unlike the case for dielectric composite materials. The magnetic losses are described by a magnetic conductivity which can be made independent of frequency and proportional to the volume fraction by choosing a certain bias. Furthermore, we showed that a certain amount of magnetic material is required in order to maintain a low reflection and that there exists a lower bound on how thin we could expect a an absorbing layer to be. Numerical calculations show that, though thin, the layer tends to be quite heavy, which might prevent the use of ferromagnetic material in absorber applications. These results may serve as guidelines when designing thin broadband RAMs. Finally, some concerns regarding particles of small size, i.e., nanoparticles, have been treated and the possibility of exciting exchange modes has been investigated. These exchange modes may be an interesting mean to increase the losses in composite materials.

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4.1.4 Bio-imaging and sensing HE, Sailing (professor, Ph.D.) Xin Li, Jun Qian, and Sailing He have presented multilayered polyelectrolyte

functionalized gold nanorods (GNRs) for the conjugation of and sensitive detection of bio-molecules. Multilayered polyelectrolyte functionalized GNRs can significantly improve the biocompatibility of cetyltrimethylammonium bromide ( CTAB) coated GNRs in a bio-environment and can diminish the toxicity induced by CTAB. Biotin, bovine serum albumin (BSA)-biotin and streptavidin are conjugated to polyelectrolyte functionalized GNRs, and the conjugates can serve as a platform for many biotin-streptavidin-based biological applications. Through the robust self-assembly effect of GNRs, biotin-conjugated GNRs are also utilized as a very sensitive probe for the detection of a small amount of streptavidin. This work is published in NANOTECHNOLOGY, 19 (35): Art. No. 355501 SEP 3 2008. Jun Qian, Xin Li, Ming Wei, Xiangwei Gao, Zhengping Xu, and Sailing He have synthesized and characterized organically modified silica nanoparticles doped with Nile Red. Silica encapsulation is relatively transparent for light and can protect hydrophobic Nile Red against denaturalization induced by the extreme bio-environment, making the entire nanoparticle hydrophilic and possess stable optical properties. The nanoparticles were conjugated with bio-molecules (such as apo-transferrin and folic acid), and our in vitro experiments revealed that these functionalized nanoparticles can serve as effective optical probes for specific targeting of cancer cells. As a preliminary study for future in vivo animal experiment, ORMOSIL nanoparticles were further co-conjugated with polyethyleneglycol (PEG) and apo-transferrin and the conjugates were also very good for in vitro targeting of HeLa cells. These bio-molecule functionalized ORMOSIL nanoparticles may serve as a robust tool for early diagnosis/therapy of cancer and other diseases. This work is published in Optics Express, Vol. 16, Iss. 24, pp. 19568–19578 (2008). 4.2 Metamaterials and optoelectronics The research group consists of:

• Sailing He (Professor) • Xin Hu (Ph.D. student) • Jianqi Shen (Ph.D. student) • Jun Song (Ph.D. student)

One important trend is that of using higher and higher frequencies, which makes it possible to use smaller and smaller devices. This in turn calls for full electromagnetic field compu-tations for e.g. devices in optical communication systems. The Division is actively involved in these new developments, in particular through its participation in the recently created Joint Research Centre for Photonics of KTH and Zhejiang University. A key person

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enabling this collaboration is Prof. Sailing He, who shares his time between KTH and Zheijang University, where he is Director of the Centre for Optical and Electromagnetic Research. An important part of the research concerns propagation and scattering of waves in new types of complex materials, including materials with negative permeabilities and permittivities and their applications in the design of new types of optoelectronic devices. 4.2.1 Metamaterials HE, Sailing (professor, Ph.D.) HU Xin (Ph.D. student) SHEN Jianqi (PhD student) Xin Hu and Sailing He have proposed a new type of notch filter based on a balanced composite right/left-handed (CRLH) transmission line. Combining such two notch filters with a Y-junction divider, a novel diplexer is designed and studied. The diplexer shows a wide and flat-top pass-band and very good isolation between the two outputs. Both theoretical analysis and experimental results are given and they agree with each other. This work is published in MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, 50 (11): 2970-2973 NOV 2008. They have also proposed a new class of negative refractive index (NRI) transmission line. Differential operational amplifiers are used to form the required lumped elements, i.e., negative-impedance-converted (NIC) inductors and capacitors. When the gain of the differential operational amplifiers in the NIC circuits is very large over the entire frequency band, the equivalent material parameters are non-dispersive, and the phase response of the new NRI transmission line can be complimentary to that of a conventional transmission line over the entire frequency band. As an application example, a broadband 1:4 power divider based on the proposed NRI transmission line is studied. The work is published in The European Physical Journal Applied Physics 2008), DOI: 10.1051/epjap:2008120. Yuntuan Fang and Sailing He have presented transparent periodic structure consisting of metamaterial (double negative) layers and matching (single negative material) layers. Through the calculation of the band structure and transmission spectrum, this kind of structure is found to be omnidirectionally transparent to some electromagnetic wave of any polarization. The working frequency and bandwidth can be adjusted by changing the thicknesses of material layers. This work is published in PHYSICAL REVIEW A, 78 (2): Art. No. 023813 Part B AUG 2008 Bowen Wang, Yi Jin and Sailing He have studied and designed a subwavelength corrugated metal waveguide to slow down the light at terahertz frequencies. The waveguide consists of two parallel thin metal slabs with periodic corrugations on their inner boundaries. Compared with structures based on engineered surface plasmons, the proposed structure has smaller group velocity dispersion and lower propagation loss. The origin of the slow wave is also explained. This work is published in APPLIED OPTICS, 47 (21): 3694-3700 JUL 20 2008

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Bowen Wang, Linfang Shen and Sailing He have introduced a simple superlens formed by a one-dimensional dielectric photonic crystal. Off-axis subwave-length focusing is achieved and studied with the equifrequency contour analysis and finite-difference time-domain simulation. Besides its advantage of simplicity, the present superlens can give a spot size much smaller than that achieved by a slab of some high-dimensional photonic crystal of negative refraction. The properties of an on-axis image achieved by the combination of two slabs of the one-dimensional photonic crystal are also studied. This work is published in JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS, 25 (3): 391-395 MAR 2008. Pu Zhang, Yi Jin, and Sailing He have studied how to cloak an object on a dielectric half-space for an observer in air. The proposed cloaking configuration has two vertical matching strips of isotropic and homogeneous material under the two bottom surfaces of a semi-cylindrical cloaking cover. Simple expression for the material parameters of the matching strips is derived. The theoretical results of cloaking are verified numerically for the incidence of plane wave and line current source. The vertical matching strips can be terminated with a finite depth by introducing some loss to the matching material. This work is published in OPTICS EXPRESS, 16 (5): 3161-3166 MAR 3 2008 Shiming Gao and Sailing He have studied the four-wave mixing (FWM) effect in a so-called left-handed material (LHM) with a third-order nonlinear response. The theoretical models for the wavelength conversion (WC) and parametric amplification (PA) based on the FWM in the LHM are established when the signal falls in the frequency range of backward or forward wave. Analytical formulas for the WC efficiency and PA gain are derived. The influences of the pump powers, the phase mismatch, and the interaction length on the performances of the WC and PA are analyzed. The phase-match dependence of the performance is reduced by carefully controlling the pump powers. This work is published in JOURNAL OF NONLINEAR OPTICAL PHYSICS & MATERIALS, 16 (4): 485-496 DEC 2007 Yi Jin and Sailing He have studied the enhancement of resonant tunnelling of a wide beam through vertical subwavelength slow-light photonic-crystal waveguides (SPCWs). An assistant horizontal SPCW with a thin side wall, whose guided modes have small propagation constants, is used as an input coupler for the vertical SPCW, and the two SPCWs form a compact composite structure to enhance drastically the resonant tunnelling. An incident wide beam can excite strongly the guided modes of the horizontal SPCW, and then resonantly tunnels through the vertical SPCW efficiently. To further improve the resonant tunnelling of a wide beam, a periodic array of vertical SPCWs (with a horizontal SPCW as an input coupler) is also investigated. With this periodic structure, a wide beam can be transmitted nearly completely. When a wide beam tunnels through the vertical SPCWs efficiently, the excited fields inside the SPCWs are very strong. This work is published in Optics Express, Vol. 16, Iss. 24, pp. 19550–19556 (2008).

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4.2.2 Optoelectronics and Microwave Photonics HE, Sailing (professor, Ph.D.) SONG, Jun (Ph.D. student) Rui Hu, Daoxin Dai, and Sailing He have presented an optimal design of a small polymeric ridge waveguide with a high index contrast. In order to reduce the leakage to the substrate and pure bending losses, the buffer layer of the present waveguide is etched partially. The single-mode condition, the bending characteristics, and the birefringence of the present small polymeric ridge waveguide are also studied. By adjusting the core width and the core height, it is possible to obtain a polarization-insensitive small polymer ridge waveguide. For the bending loss, the numerical results show that the dominant part is the transition loss between the straight and bending sections (other than the pure bending loss) and the transition loss could be reduced greatly by introducing a lateral offset. However, the transition loss is still too large to obtain a very small bending radius (e.g., 10 mu m). When only the pure bending loss is necessary to consider in some special case (e.g., microrings without any transitions), one can have a bending radius less than 10 mu n due to the possibility of low pure bending loss. The work is published in JOURNAL OF LIGHTWAVE TECHNOLOGY, 26 (13-16): 1964-1968 JUL-AUG 2008. Yongbo Tang, Yichuan Yu, Yuqian Ye, Urban Westergren and Sailing He have analyzed the modulation response of an arbitrarily segmented traveling wave electroabsorption modulator (TW-EAM) with a non-periodic electrode layout with an effective approach based on the transmission line theory. An optimization method based on a genetic algorithm is used to optimize the segmented electrode with additional capacitive pads for a TW-EAM. Optimized electrode structures are given for 165 mu m-length devices under standard 50 Omega RF termination condition and 210 mu m-length devices with smaller integrated resistors. Great enhancement of performances in modulation response is achieved as compared to the periodic design reported previously. The simulation with the parameters extracted from measurement results suggests that a 3 dB-bandwidth over 100 GHz could be achieved. The eye diagram from the simulation demonstrates that such devices would be competent for a 100Gb/s optical network. This work is published in OPTICS COMMUNICATIONS, 281 (20): 5177-5182 OCT 15 2008. Yaocheng Shi, Sailing He, and Srinivasan Anand have presented the design, fabrication, and measurement of an ultracompact directional coupler in InP/InGaAsP/InP. By utilizing the lag effect in the dry etching process, in one etch step, deeply etched asymmetric waveguides with a shallow groove in between are fabricated. This special property enhances the coupling efficiency for the directional coupler and thus makes the device ultracompact. They have demonstrated directional couplers as short as 55 mu m, which is only 1/30th the length of the conventional design. This work is presented in OPTICS LETTERS, 33 (17): 1927-1929 SEP 1 2008. Xue-Wen Chen, Choy, Wallace Choy, and Sailing He have studied a dual-shell structure consisting of a silica buffer shell and a metallic outer shell for highly efficient and tunable fluorescence. The enhanced Purcell effect due to the plasmonic resonance and the

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dependence of the resonance on the structural parameters are analyzed and discussed through a classical electromagnetic approach. With the present dual-shell structure a fivefold enhancement of the fluorescence efficiency can be achieved for a nanofluorophore comprised of multiple tetramethylrhodamine isothiocyanate dye molecules, as compared to the nanofluorophore within a single silica shell. Furthermore, the peak wavelength of the fluorescence spectrum can be tuned easily (due to the variation of the surface plasmon resonance) by over 50 nm when the refractive index of the ambient material varies from 1.3 to 1.6. This work is published in JOURNAL OF APPLIED PHYSICS, 103 (2): Art. No. 024301 JAN 15 2008. Daoxin Dai and Sailing He have presented a design procedure for an arbitrarily tapered multimode interference (MMI) coupler based on Si nanowaveguides. First a series of the effective indices of the zeroth and first eigenmodes in multimode waveguides are obtained as the core width increases by using a full-vectorial finite-difference method. Two polynomial functions are used to fit the two relations between the effective indices and the core width. The phase difference Delta phi between the zeroth and first eigenmodes can then be easily calculated when the light goes through any given arbitrarily tapered MMI section. By making the phase difference Delta phi equal to a certain value Delta phi(0) required for an N-fold self-imaging, the length of a MMI coupler is determined. With the present design procedure, an ultrashort 2 x 2 parabolic MMI coupler is designed as an example. The size of the designed ultrashort MMI section is only similar to 1.4 mu m X 4.7 mu m. This work is published in APPLIED OPTICS, 47 (1): 38-44 JAN 1 2008. They have also presented a design for diminishing the polarization-dependency of a Si nanowire-based multimode interference (MMI) coupler by using a tapered MMI section. The entrance width and waist width of the tapered MMI section are optimized to obtain a polarization-insensitive MMI length for N-fold self-imaging. The MMI section with a diminished polarization-dependency has a relatively large entrance width, which is beneficial to the separation of adjacent access waveguides for minimizing the coupling between them. One can tune the power splitting ratio of a 2 x 2 Si-nanowire MMI coupler by adjusting the entrance and the waist width of the tapered MMI section. This work is published in IEEE PHOTONICS TECHNOLOGY LETTERS, 20 (5-8): 599-601 MAR-APR 2008. Liu Yang, Daoxin Dai and Sailing He have presented a photonic Si ridge wire with a submicron metal heater and the associated thermal analysis. When the up-cladding thickness becomes thinner, the thermal response becomes faster while the temperature at the core region remains almost the same. When the under-etched depth in the insulator layer increases, the stable temperature increases linearly at the same power consumption. This indicates that a deeper etching is preferred to achieve a lower power consumption (for the same temperature increment). Their numerical simulation also shows that the power consumption of the present Si waveguide structure is almost less than 1/10 of that for a conventional one and the response time is about half of that of the conventional one. This work is presented in OPTICS COMMUNICATIONS, 281 (9): 2467-2471 MAY 1 2008. They have also presented an ultracompact widely tunable thermooptical (TO) microring resonator (MRR) filter based on Si nanowires. The Si nanowire waveguide has a SiO2 insulator, Si core, a SiO2 up-cladding, and a thin metal film at the top. The metal circuit along the microring is used as a submicrometer heater which has the same width as the Si

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nanowire waveguide. The up-cladding is optimized to reduce the light absorption of the metal as well as to have a good heat-conduction from the heater to the Si core. Two pads used as the contact points for the probes connecting to the electrical power are perpendicularly connected to the microring by using optimized T-junctions (with a low excess loss of about 0.06 dB per T-junction). With such a design, the present thermally tunable microring resonator (MRR) can be fabricated by using a standard fabrication process with a single lithography process, which is much simpler than the fabrication with double lithography processes used for the conventional TO components. Finally, the simulation results show that the designed MRR has a wide tuning range of about 20 nm with a low heating power of 5 mW. This work is published in (IEEE/OSA) JOURNAL OF LIGHTWAVE TECHNOLOGY, 26 (5-8): 704-709 MAR-APR 2008 Ning Zhu, Jun Song, Lech Wosinski and Sailing He have proposed a polarization-insensitive design of an echelle grating (or etched diffraction grating) demultiplexer based on silicon nanowires, by introducing a polarization compensation area in its free propagation region. The polarization-dependent wavelength shift of the present device has been compensated at the whole spectral range. For a design with nine channels and 10-nm channel spacing, when the wavelength shift at the central channel 1550 nm is. completely compensated, the wavelength shifts of the two edge channels are only 0.14 and 0.15 nm, which are acceptable. This work is published in IEEE PHOTONICS TECHNOLOGY LETTERS, 20 (9-12): 860-862 MAY-JUN 2008 Ning Zhu, Daoxin Dai, and Sailing He have presented a hybrid method combining the three-dimensional (3D) beam propagation method (BPM) and a 3D finite-difference time-domain (FDTD) method for the simulation of multimode-interference (MMI) couplers based on silicon-on-insulator (SOI) nanowires. This hybrid method makes it possible to have a robust analysis for the reflection properties while avoiding a time-consumed computation with a simplex 3D-FDTD simulation. The reflected power is sensitive to both the length and the width of the MMI coupler and thus one should choose the optimal values for good self-imaging. Furthermore, the reflection could be reduced by introducing tapers between the MMI section and the access waveguides. This work is presented in OPTICS COMMUNICATIONS, 281 (11): 3099-3104 JUN 1 2008 Hongyan Fu, Haiyan Ou, Kun Zhu, Edvin Remb, and Sailing He have proposed, theoretically discussed and experimentally demonstrated a novel tunable and reconfigurable microwave photonic filter based on two cascaded modulators and a dispersive medium. A single-wavelength LD and a modulator (either a Mach-Zehnder modulator or a phase modulator which can avoid the do bias drift problem) are used to obtain a multi-wavelength optical source. By adjusting the modulation frequency and the bias voltage on the modulators, the wavelength spacing and the relative amplitude of the optical tones change, thus making the filter tunable and reconfigurable. The experimental results show that the proposed filters have good tunability and reconfigurability and the mainlobe-to-sidelobe ratio of around 25 dB is achieved. The work is published in OPTICS COMMUNICATIONS, 281 (22): 5550-5554 NOV 15 2008.

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Haiyan Ou, Biao Chen, Hongyan Fu, Kun Zhu and Sailing He have proposed and experimentally verified a frequency doubling approach for optical generation of tunable microwave and millimetre-wave signals. The experimental setup is based on an optical phase modulator and a simple uniform fibre Bragg grating. The generated signal is of high quality and can be tuned. This work is published in ELECTRONICS LETTERS, 44 (2): 131-133 JAN 17 2008. 4.3 Electromagnetic compatibility (EMC) The EMC group in 2008 consisted of:

• Rajeev Thottappillil (prof., main supervisor) • Daniel Månsson (Ph.D. Oct. 2008, Researcher, now at Samarkand2015) • Nelson Theethayi (Ph.D. Sept. 2005, Researcher, at Bombardier Transportation

since May 2008) • Justinian Anatory (Post-doc, University of Dar es Salaam, Tanzania) • Surajit Midya (Ph.D. student) • Ziya Mazloom (Ph. D. student) • Kelin Jia (Ph.D. student) • Siti Fatimah Jainal (Ph.D. student) • Helin Zhou (visiting Ph.D. student) • Dr. Mats Bäckström, Saab Communication, Dr. Thorsten Schütte, Rejlers

Ingenjörer AB, and Dr. Dierk Bormann, ABB Corporate Research (Co-supervisors for Ph.D. students)

The research on electromagnetic compatibility explores the mechanism by which various sources produce electromagnetic disturbances, how disturbances couple to other systems, and how the systems can be protected against electromagnetic interference, and thereby enhance its reliability. The research is multidisciplinary where electrical engineering, electromagnetics and physics of materials come together. The group started to move from Uppsala University from Sept. 01, 2008. Main focus of research work at present is to develop new knowledge and technologies for reliable operation of distributed networks such as railways, communication and power in the presence of electromagnetic disturbance from natural and man-made sources, including lightning, equipment generated interference, and intentionally created high power electromagnetic fields. Main projects are investigation of lightning and other EMI effects in the railway network, susceptibility of civilian infrastructure to intentional EMI, lightning interaction with tall towers, and broad-band power line communication for rural applications. Courses on EMC at both undergraduate and graduate levels are offered. Besides, seminars on EMC and lightning protection are conducted for industrial partners. The group also offers help to industry on questions related to lightning protection and EMC. The group also plays a leading role in the EU project COST P18: The Physics of Lightning Flash and its Effects (www.costp18-lightning.org).

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4.3.1 Electromagnetic compatibility issues in railway network

Project leader: Rajeev Thottappillil Ph.D. students: Surajit Midya, Ziya Mazloom, Kelin Jia, Siti Fatimah Jainal

The signaling and train control systems in modern railways are highly automated. Digital electronics can realize a great amount of intelligence and flexibility in the control functions and they find increasing use in railway systems. However, there is always a concern about the reliability and safety issues because of the low threshold destruction energies associated with modern electronics. Before the advent of modern electronics, key components in the signal and control networks were electromechanical and were largely insensitive to electromagnetic disturbances. Railway networks are extensive and modernization of signal and control systems happens only in stages at different times. It is not unusual to find transient related problems in a section of the network after upgrading due to inadequate lightning protection design (or EMC design) of the existing network in which the new module is introduced.

A protection strategy based on overall reliability analysis of the system in the presence of EMI is required for railway systems. It should be possible to estimate the probability of EMI due to lightning, locomotives, pantograph arcing or any other electromagnetic source and from that decide the acceptable risk levels. The research in this project will make it possible to locate possible weak points in the system using developed simulation tools. The emphasis is placed on developing methods and processes for tackling EMI problems on existing and new systems using computer simulations and its verification by actual measurements of EMI in railway systems. These methods and processes shall also include sets of rules to follow for obtaining better system hardness against EMI. At the same time these methods and processes shall be applied in practice to verify their usefulness on real systems (e.g. ERTMS system). The existing railway control and signaling networks (ERTMS Level 1) and the upcoming networks (ERTMS Level 2 and 3) are being studied. The computational models developed for analyzing the interaction of lightning with the railway network is being extended to cover interference at low frequencies to communication cables, at high frequencies to ERTMS communication equipments and the new threat of intentional EMI. This will lead to reduced traffic disruptions and increased capacity.

(funded by Swedish National Rail Administration (Banverket)) 4.3.2 Susceptibility of critical infrastructure to intentional EMI Project leader (for KTH part): Rajeev Thottappillil Main partners: Daniel Månsson, Samarkand2015; Mats Bäckström, Saab Communications The vulnerability from intentional electromagnetic interference (IEMI) has increased in the recent decades due to the widespread dependence of the civil society on sensitive electronic systems and proliferation of radiation sources. There are concerns about IEMI being used against civilian critical infrastructure by terrorist groups or other rough elements. The large

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spatial distribution of many civilian facilities and critical infrastructures (e.g., power generation, communications, train system, etc.) presents many unexpected ports for an attacker as the majority of the parts of these systems are not protected or secure. Target systems may face disturbances that are both radiated through an antenna or through a connected conductor (e.g. a power socket). One large distributed system that has been investigated is the Railway system. As the new European Rail Traffic Management System (ERTMS) will utilize wireless communication for communication and control of the trains the vulnerability from different radiating high power electromagnetic (HPEM) sources have been investigated. Possible threat scenarios and estimates of the vulnerability to the communications system were made. A method for the susceptibility determination and classification of civilian facilities to intentional EMI is developed. The backbone of our modern society is the electric power grid, without this the rest of society will immediately or gradually grind to an inevitable halt. However, just a few research programs, mainly conducted in the U.S., have been reported combining power systems and the threat from electromagnetic pulses, mainly from pulses created by a nuclear explosion in the atmosphere (so called NEMP). In the EU financed Critical Infrastructure Project (CIP) “Assessment and mitigation of risk for disabling control centre of large power networks by intentional radiofrequency interference” (Reference Number: JLS/2007/CIPS/015) the threat to the power grid from a portable electromagnetic source (could be truck mounted) is investigated. The project coordinator is Samarkand2015 (Sweden) and partners include KTH, TNO (Netherlands Defense Organization for Applied Scientific Research) and MLSPI (Microwave Laboratory Semiconductor Physics Institute, Lithuania). The research is performed in close cooperation with Svenska Kraftnät and the industry. (funded by Swedish National Rail Administration (Banverket), European Union) 4.3.3 Broad-band Power Line Communication for Developing Countries Main Researcher: Justinian Anatory, University of Dar es Salaam, Tanzania Cooperating Partners: Nelson Theethayi, Rajeev Thottappillil Broad-band Power Line Communication (BPLC) is a powerful emerging technology for internet access. In advanced countries it is competing with TV cables, telephone lines and optical fiber. In a country like Tanzania where penetration of TV cables, telephone lines, and optical fiber are far less compared to the power lines, BPLC for internet access is the obvious choice. Technology for this has not matured and has to be developed further. A plan of action is envisaged for developing some parts of this technology at University of Dar es Salaam. The research concentrates on the following activities. 1. Signal propagation characteristics of the electrical wiring cables used in homes and

offices of Tanzania by laboratory testing and model calculations. 2. Quantifying the electromagnetic emission from the electrical wiring configurations used

in homes and offices of Tanzania using models and calculations. Explore configurations that reduce emissions.

3. Actual measurements on signal propagation and electromagnetic emission in a real home and office to validate the calculation models.

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4. Characterize the signal propagation characteristics and emission of outdoor overhead power lines and cables used in Tanzania to distribute power from transformer secondary.

(funded by SIDA, Swedish International Development Agency) 4.3.4 Lightning Interaction with Tall Towers Project Leader: Rajeev Thottappillil Collaborator: Gerhard Diendorfer, ALDIS Visiting Ph.D. student: Helin Zhou This research attempts to answer the following questions related to lightning interaction with communication towers. Can tall towers influence the incidence of lightning in the area where the tower is situated? Are the parameters of the lightning, such as peak currents, influenced by the presence of the tower where lightning strikes? What would be the electric and magnetic field environment in the near vicinity of the tower and far from the tower when compared to the corresponding values with lightning striking level ground? Are lightning protection methods designed primarily to protect the communication equipments sufficient to prevent lightning surge transfer to near by local networks? The experiments in the project are being carried out using a communication tower that is 100 m high and situated on mount Gaisberg in Austria, in collaboration with partners from ALDIS (Austrian Lightning Detection and Information System http://www.aldis.at/research/projects.html, which is part of Austrian Electricity Association, Technical University of Vienna, Austria and the Swiss Federal Institute of Technology, Lausanne (EPFL), Switzerland. This tower is struck by lightning more than 50 times in a year.

(funded by Swedish Research Council (VR)) 4.3.5 EU COST Action P18 on Physics of Lightning Flash and its Effects Chair: Prof. Rajeev Thottappillil Co-chair: Prof. Farhad Rachidi, EPFL, Switzerland Project Website: http://www.costp18-lightning.org/

The research in lightning is as old as the research in electricity. In 1750 Benjamin Franklin suggested an experiment that later proved lightning is an electrical discharge. Since those early days research on lightning has come a long way, but still a long way to go.

The main objective of the COST Action P18 is to increase the knowledge of the physics of the lightning discharge and of its effects on natural and man-made systems. This will include the following sub-objectives, but not limited to them.

• To understand and model the different physical processes in the lightning channel.

• To understand and model the lightning attachment to objects.

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• Measurement of characteristics of lightning flashes in Europe and an establishment of a data bank on the lightning parameters, including a databank on the characteristics of the electromagnetic radiation of lightning from ELF to gamma rays.

• Develop models for the inverse source problem in lightning; that is, inferring the characteristics of the processes in the lightning channel from remote measurements of the electromagnetic waves associated with lightning.

• To understand the mechanism of the production of the trace gas species in the atmosphere by the hot plasma channel and corona in lightning discharge.

• To understand the connection between the particular characteristics of lightning flashes and the associated observation of luminous events in the mesosphere and the lower ionosphere.

Fulfilling the above objectives would increase our knowledge of the most important scientific issues in lightning research, namely, the phenomenology of processes in the lightning flash, lightning initiation in thunderclouds, mechanism of lightning stepped leader and dart leader, mechanism of lightning attachment to objects, mechanism of lightning return stroke, mechanism of X-rays and gamma-rays emission associated with lightning, mechanism of ball lightning, mechanism of trace gas species production by lightning, and the connection between lightning and upper luminous events in the atmosphere. In addition, increased knowledge of the physics of lightning would help several scientists and engineers in devising better strategies for protecting sensitive systems from the deleterious effects of lightning and to understand the impact of lightning on the chemistry of the atmosphere and on the global electric circuit.

Research groups from 25 countries are taking part in this Action. (funded by COST program of European Science Foundation (http://www.cost.esf.org/) Period: 2005 – 2009) 4.4 Electrotechnical modelling The research group consists of:

• Göran Engdahl (Prof., main supervisor) • Lars Austrin (Ph.D. student) • David Ribbenfjärd (Ph.D. student) • Mohsen Torabzadeh-Tari (Ph.D. student) • Hanif Tavakoli (Ph. D. student)

This research area comprises development of theory, methods and tools for electric power components including magnetic and other materials. The governing approach is to model material related electrotechnical phenomena and processes by use of Maxwell’s equations and material algorithms in a system perspective.

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Since the middle of the 80’s a number of projects have been performed regarding characterization and modelling of apparatus and systems comprising magnetostrictive and magnetic materials. That work has been focused on characterization and modelling of magnetic materials. Since the middle of the 90’s the activities also include modelling of transformers, electromechanical actuators and power electronics, electromachines and magnetic amplifiers for aircraft applications. A magnetic and materials modelling laboratory has been built up around characterization of magnetic and functional materials. The outcome of these measurements are stored in databases and thereafter used as input to computer algorithms included in simulation programs. These programs are finally aimed at helping engineers and scientists in electrotechnical design projects. The activities of the modelling group during the year has been related to

• Magnetic hysteresis • Power transformers • Electromechanical actuators • Magnetostrictive actuators • Magnetic amplifiers • Power supply systems • Cooling systems

Some recent results are:

• Improved algorithm for extraction of hysteresis model parameters • Improved algorithm for static hysteresis • Created, simulated and experimentally verified dynamic hysteresis model for core

material with poor field penetration • Optimisation of an electromechanical actuator for More Electric Aircraft

applications • Analysis of a pulsed power supply system for unmanned aerial vehicle • Optimisation approach of coil and magnetic circuit of magnetostrictive actuators.

4.4.1 Applied magnetostriction – Design tools and experimental methods

ENGDAHL, Göran (professor, Ph.D.) Giant magnetostrictive materials are used in underwater sonar applications, high-pressure pumps, active vibration control, damage analysis and other sensor applications. However, the design of magnetostrictively based technology is by no means standardized and no commercial design tools are available. Therefore, design methods and computer aided tools for the modeling and design of giant magnetostrictively based systems have been

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developed in this project for several years, and have now become a valuable and unique design tool. The code is today by no means user-friendly but more a model for the specialist. An attempt has now been done to make the code user-friendlier. The old code is also under conversion to a modern software environment for simulation of dynamic systems as DYMOLA and MATLAB. An experimental evaluation system for dynamic measurements and assessments of magnetostricitive actuators has been constructed and further developed. A measurement and data acquisition system has also been installed, with the possibilities of advanced control and data processing. The experimental evaluation and data acquisition systems have been tested using several magnetostrictive actuators of different design. These tests show that the experimental evaluation system is functioning as a well-defined test environment for magnetostrictive actuators. The experimental evaluation system has also been equipped with a new electronic device developed at the department to automatically control the mechanical pre stress level on the actuator. (Sponsored by EU) 4.4.2 Transformer modeling for development of the FRA method for life time estimation

and risk management

ENGDAHL, Göran (professor, Ph.D.) TAVAKOLI, Hanif (Ph.D. student) The overall goal of this project is to develop a transformer model that can be used for further development of the FRA method. The Frequency Response Method (FRA) makes it possible to detect changes of the electrical properties and the geometrical shape the transformer core and windings. Thus information regarding the condition and reliability of the transformer can be obtained for life time estimation and risk management. The project is also related to project 4.6.2. The project includes further development of the existing electromagnetic model including the ferromagnetic core and use of it for the interpretation of so-called FRA-spectra. (Sponsored by the Competence Centre in Electral Power Engineering at KTH, EKC2) 4.4.3 Electromagnet transformer modeling including the ferromagnetic core

ENGDAHL, Göran (professor, Ph.D.) RIBBENFJÄRD, David (Ph.D. student) The purpose of this research project is to further develop models for dynamic simulation and loss calculations in transformers. The project builds on a number of other projects that

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have been performed at the department in recent years, regarding characterization and modeling of magnetic materials in electrotechnical apparatuses and systems. The losses in transformers include hysteresis, eddy currents, skin effect and leakage flux. The aim is to investigate these losses in detail and make more exact models for them. The intention is that these models should be usable in transformer design, studies of transient operation modes and diagnostics of the physical condition of transformers. During the year the static hysteresis model has been further developed to give better agreement with measurements. A dynamic hysteresis model has also been further developed. Measurements have be done for verification of the models. (Sponsored by the ELEKTRA program) 4.4.4 New electrical components for aircrafts (MEA-systems)

ENGDAHL, Göran (professor, Ph.D.) AUSTRIN, Lars (Pd. D. student) TORABZADEH-TARI, Mohsen (Pd. D. student) The project constitutes a continuation of a previous project MEA with the object to find technology for upgrading the electric power system in existent aircrafts or technology for further and new development of aircrafts. This project comprises analysis and development of methods for dimensioning of new electrical components for aircrafts as electrical machines, power electronics, magnetic amplifiers etc. The intention is that the new technology will imply lower costs, reduced weight and maintenance and improved reliability and performance. The project is performed in close collaboration with Saab. A Ph. D. thesis was presented on December 15 2008. (Sponsored by NFFP) 4.5 Antenna theory and design The research group consists of: • Sailing He (Professor) • Lars Jonsson (Associate professor) • Martin Norgren (Associate professor • Patrik Persson (Research associate, Ph.D.) • Peter Fuks (Senior Researcher, Ph.D.) • Anders Ellgardt (Ph.D. student)

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Electromagnetic waves are launched and received by antennas. In response to the needs created by the above-mentioned trends, antenna theory and design has become another main area of research. The focus is on the development of new analytic and numerical methods of importance for the design of advanced antenna configurations, such as broad-band antenna arrays and antenna arrays conformal to some prescribed (curved) surface. A new area, which is vigorously pursued, is antenna applications exploiting the band structure of photonic crystals. 4.5.1 Broadband antennas HE, Sailing (professor, Ph.D.) Jiechen Ding and Sailing He, et al. have studied a compact printed ultra-wideband slot antenna with superior multiple band-notched characteristics. The size of the UWB slot antenna is minimized, and multiple split ring resonators are printed inside the inner patch to achieve multiple notch frequency bands. As a practical example, a UWB antenna (working from 2.4 to 10.1 GHz) etched with two sets of split ring resonators are fabricated and its VSWR and radiation patterns are measured. The measured results agree well with the simulation, and the two notch frequency bands are centered at 3.65 and 5.75 GHz. This work is published in MICROWAVE AND OPTICAL TECHNOLOGY LETTERS (49(12): 3056-3060, 2007). Jun Hu, Salman Khan, Jiang Xiong, and Sailing He have presented a compact circular AXE-shaped patch antenna for miniaturized application. The proposed design is further modified for dual band 2.4/5.5 GHz wireless application. The measured return loss is from 2.38 similar to 2.42 GHz and 5.41 similar to 5.59 GHz suitable for dual band WLAN application. Same design procedure can also be applied for miniaturized applications. The miniaturization process shifts the resonance at 1.71 GHz instead of 2.5 GHz in case of simple circular patch. The radiation pattern and gain for dual band wireless antenna is also measured and presented. The work is published in JOURNAL OF ELECTROMAGNETIC WAVES AND APPLICATIONS, 22 (11-12): 1655-1660 2008. Jiechen Ding, Zhili Lin, Zhinong Ying and Sailing He have presented a compact printed ultra-wideband slot antenna with superior multiple band-notched characteristics . The size of the UWB slot antenna is minimized, and multiple split ring resonators are printed inside the inner patch to achieve multiple notch frequency bands. As a practical example, a UWB antenna (working from 2.4 to 10.1 GHz) etched with two sets of split ring resonators are fabricated and its VSWR and radiation patterns are measured. The measured results agree well with the simulation, and the two notch frequency bands are centered at 3.65 and 5.75 GHz. This work is published in MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, 50 (5): 1446-1446 MAY 2008 Salman Naeem Khan, Jun Hu, Jiang Xiong and Sailing he have presented an apollonian shaped ultra-wideband circular monopole antenna based oil descartes circle theorem. Different self similar geometries front DCT are analyzed and optmized for UWB applications. The proposed design is slightly modified to ensure all overall smooth current

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distribution limited by the Junction point nature of the fractal geometries. The experimental results are compared with conventional circular disk monopole (and annular monopole antenna. The measured return loss of the proposed design below - 10 dB is from 2.4 to over 40 GHz and its radiation pattern is omni-directional compared with circular disk and annular antennas in most of its impedance bandwidth. Moreover due to the fractal shape, the proposed design has less weight and wind loading effect. This work is presented in MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, 50 (6): 1605-1608 JUN 2008 4.5.2 Wide scan and wide-band array antennas ELLGARDT, Anders (Ph.D. student) NORGREN Martin (associate professor, Ph.D.) During 2008 Anders Ellgardt has continued his work in the NFFP 4 project FLYGANT. Antenna elements at the edges of phased arrays behave differently than the elements in the middle of the antenna. This effect is due to that the elements in the phased array couples to the neighbouring elements. The edge effects are difficult to study with numerical codes due to the size of the antenna, and analytical solutions only exist for simplified elements such as delta-gap fed dipoles. We have studied a tapered-slot array with a triangular grid that is finite in one direction. This approximation reduces the size of the problem, but still gives useful information of the performance of the finite array. By comparing infinite arrays with a truncated excitation and finite arrays it is possible to determine the cause of the edge effects. To calculate the raw data needed for this analysis the active reflection coefficient for the infinite array must be computed for arbitrary phase shifts. The numerical tool used is restricted to phase shifts corresponding to visual space. A method has been developed to calculate arbitrary phase shifts for infinite array using numerical codes with a limited phase shifts. (Sponsored by NFFP4) 4.5.3 Array antenna in metallic structures

JONSSON L, Lars (professor, Ph.D.) MOTEVASSELIAN A (Ph.D. student) An array antenna that is mounted in the front edge of an airplane wing poses several challenges. Apart from common design parameter on the antenna such as gain, directivity, wide-band, high power etc, which depend strongly on the surrounding metallic shapes. There are also strong requirements on the radar cross section. This implies that the antenna design needs to take into account the surrounding material, a number of screening techniques enters into this design. To understand the limitations and possibilities in this mix of antenna surrounding and antenna properties is the key element to this project. At present time we have made extensive studies on screening techniques to reduce the radar cross section. It is a joint industry/academia project, financed by industry and Vinova under the name of NFFP 4, SIGANT. The project started in May 2007 and runs for two years. (Sponsored by NFFP4)

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4.6 Insulation diagnostics The research group consists of:

• Roland Eriksson (Prof., main supervisor) • Hans Edin (senior lecturer, assistant supervisor) • Valentinas Dubickas (Ph.D. student) • Cecilia Forssén (Ph.D. student) (Until June 2008) • Nathaniel Taylor (Ph.D. student) • Kristian Winter (Ph.D. student) • Nadja Jäverberg (Ph.D. student)

The integrity of the electrical insulation is of greatest importance in the reliability of high voltage equipment. Failure of the insulation system may cause an interruption of service, or in worst case a complete damage of the equipment with a costly replacement. The research work aims at developing practical and reliable methods that can diagnose the degradation status of the electrical insulation. The results from diagnostic methods can be used in long-term maintenance strategies but also for short-term estimates of the failure risk in relation to the risk. The diagnostic techniques under investigation are based on measurement of different kind of dielectric response. Low-frequency dielectric spectroscopy is developed as a general tool to diagnose degraded insulation systems. The applicability of high-frequency methods for a more precise localization of defect insulation is under development. Partial discharge activity is measured and analyzed when the insulation system contain voids, delaminations, cracks or over-stressed surfaces, etc., that may cause local discharges. Research on new composite materials with SiC for field grading applications is performed as an industrial Ph.D. project at ABB. This would give a possibility to optimize the field control in highly stressed devices like, for example, cable terminations. 4.6.1 Physical modelling of partial discharges at variable frequency of applied voltage EDIN HANS, Hans (Ph.D.) FORSSÉN, Cecilia (Ph.D. student) The aim of the project is to increase the understanding of measurements of partial discharges at variable frequency (VF-PRPDA) and to relate the measured quantities to the physical properties of the electrical insulation. An increased understanding of this relationship would improve the possibilities to judge the condition of the insulation and to estimate the risk of failure for an insulation system, for example cable insulation or machine insulation. The results to be obtained from the project are:

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- A model of partial discharges at variable frequency of applied voltage. Physical properties of interest are the material parameters and their dependence on temperature, frequency, moisture content and ageing; and the geometry of a cavity, its shape, location and discharge behaviour. - Measurements on simplified test objects to validate the model. - List of characteristics for different PD sources that can be used for interpretation of complex measurements on complete insulation systems. The results from the project so far are: - The VF-PRPDA technique has been applied to a test object containing a cylindrical cavity in an otherwise homogeneous insulation of polycarbonate. The frequency of the applied voltage was varied in the range 10 mHz – 100 Hz. It was concluded that with the VF-PRPDA technique, it is possible to distinguish between cavities of different size and between insulated cavities and cavities placed against an electrode. - A field model of PD in an insulted cylindrical cavity at variable frequency of the applied voltage has been created. - Experiments and models for a cavity between spherical electrodes has been achieved A doctoral thesis was presented on June 4 2008. (Sponsored by the Competence Centre) 4.6.2 Dielectric diagnostics of machine insulation by dielectric spectroscopy and variable

frequency phase resolved partial discharge analysis EDIN, Hans (Ph.D) TAYLOR, Nathaniel (Ph.D. student) Previous work at the institution has developed the use of variable applied frequency in measurements of dielectric response and phase-resolved partial discharges. The aim of this project is to investigate the application of these extended dielectric response and partial discharge methods to the specific case of insulation systems in large rotating electrical machines such as power-station generators and large industrial motors. These machines' insulation systems are based on mica flakes in a bituminous or epoxy binding. Sites of partial discharges and degraded dielectric properties may be in the insulation between conductors, or between conductors and the earthed stator iron, or in the end-winding region where high axial fields on the insulation surface may exist and are moderated by semiconducting coatings. Use of the variable-frequency methods together is expected to allow better localisation and specification of insulation problems.

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Adaptations to existing equipment are needed to obtain a system that can make all required measurements rapidly, accurately and with a large extent of automation to reduce errors during repetitive tests. Measurements will be made upon insulation systems in machines in the field and on bars of various condition. From these measurements, knowledge and understanding of the usefulness and meaning of information from the advanced diagnostic methods will be obtained, leading to a methodology for insulation system assessment. Field measurements have been performed on a hydro-power generator. New stator coils have been thermally aged with an accelerated thermal ageing procedure. The thermal ageing introduced defects that after the ageing suffered due to partial discharges. A licentiate thesis was presented on November 23 2006. (Sponsored by the ELEKTRA program) 4.6.3 On-line diagnostic methods for power cables EDIN, Hans (Ph.D) DUBICKAS, Valentinas (Ph.D. student) For this day the most common power cable insulation diagnostic techniques are off-line, the cable is disconnected from the grid during the diagnostics. Partial discharge detection and dielectric loss measurements diagnostics are successfully used off-line. New technique, time domain reflectometry, is being developed in our department. It should allow water trees growing in the insulation to be localised. Development of an on-line diagnostic system for the power cables’ insulation is the goal of the project. The work is concentrated on the Time Domain Reflectometry (TDR) technique application for measurements on-line. The on-line measurements are performed while the power cable is connected to high voltage and is supplying the load. Therefore high voltage and the load variations could be used as a differentiating parameter in the diagnostics. However in order to perform the on-line measurements the couplers are needed to decouple the measuring equipment from the high voltage. Four types of couplers were built: inductive coupler, Rogowski coil, capacitive coupler and coupling capacitor. The couplers were investigated and high frequency models were built. Temperature dependence upon pulse propagation was investigated both in laboratory and in field-measurements by studying the consequence of load cycling. Field measurements were performed on Vattenfalls 24 kV net in Botkyrka. An on-line copupling capacitor principle was tested for TDR experiments. Field measurements were also performed on Ekerö Energi 24 kV net .

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A high frequency measurement superimposed on high voltage system (HF-o-HV) has been developed that can be utilised for high frequency characterisation of high voltage cables when they simultaneously are stressed by a low frequency (50 Hz and below) high voltage, up to 20 kV. Physical based models of water tree response has been developed. (Sponsored by the ELEKTRA program) 4.6.4 Diagnostic criteria and new diagnostic methods for machine insulation EDIN, Hans (Ph.D) WINTER, Kristian (Ph.D. student) This project was started in novemeber 2006 with the aim to develop criteria of machine stator-insulation degradation based on a comparison of electrical measurements like dielectric spectroscopy, variable frequency partial discharge analysis, surface conductivity analysis and physico-chemical analysis methods. Within the project, new excitation and detection/analysis methods will be tested. An experimental setup has been designed that allows for a uniform surface degradation of the surface of an insulating material by corona discharges. Surface conduction measurements of the degraded surface is performed as one measure of the degradation. (Sponsored by the Competence Centre) 4.6.5 Evaluation of electrical insulating properties of nanocomposites for high voltage applications EDIN, Hans (Ph.D) JÄVERBERG, Nadja (Ph.D. student) This project was started in September 2007. Nanocomposites is a class of insulating materials that is based of filling insulating organic materials with inorganic fillers. In nanomaterials the size of the filler particles has at least one dimension that is less than 100 nm. Common fillers are e.g. sphere like particles of TiO2 and Al2O3. Another class is clays that contains flakes of inorganic materials, e.g. of the mineral montmorillonite. The dielectric properties of these materials and the voltage endurance properties of the nanocomposites will be investigated. The project has a sister project at the department of fiber- and polymer technology where the new nanocomposites will be developed. A measurement system for electrical tree growth has been develeoped. Simultaneous measurements of electrical tree growth and partial discharges can be studied. (Sponsored by ELEKTRA)

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4.7 Reliability Centred Asset Maintenance (RCAM) The research group at KTH consists of:

• Roland Eriksson (Prof., supervisor) • Lina Bertling (Ph.D., project leader and supervisor) • Patrik Hilber (Ph.D. project leader and assistant supervisor) • Stefan Arnborg (Ph.D. assistant supervisor) • Michael Patriksson (Ph.D. assistant supervisor) • François Besnard (Ph.D. student) • Tommie Lindquist (Ph.D. student until June 2008) • Julia Nilsson (Ph.D. student) • Johan Setréus (Ph.D. student) • Carl Johan Wallnerström (Ph.D. student)

Maximal asset performance and minimal life cycle cost are important objectives for electric power system managers. These objectives are constrained by the requirements of customers and regulators concerning the reliability of power supply. The re-regulation of the electricity market has further increased the incentives for a cost effective and efficient use of available assets. Maintenance planning constitutes one tool for achieving the goals with respect to all parties. Resulting in a research area on new strategies for more effective maintenance techniques and asset management methods, interesting from both industry and research perspective. The generally known reliability-centered maintenance (RCM) method defines cost-efficient maintenance programs. However the method is generally not capable of showing the benefits of maintenance on system reliability and costs. A reliability-centered asset maintenance (RCAM) method has been developed at the division (Bertling 2002). This approach improves the RCM method by providing quantitative results when: relating the effect of maintenance on component failure rates to the system reliability, and for comparing the costs of different maintenance strategies. The overall objective for this research group is to further develop the RCAM for an optimal handling of assets in the electric power systems, as well as the own expertise in the area. The research group has the following research topics;

• maintenance planning and optimization including reliability-centered maintenance (RCM) methods

• reliability modeling and assessment for complex systems

• lifetime- and reliability modeling for electrical components

with application areas of; distribution systems, transmission components (breakers, disconnectors, and transformers), hydro power, wind power, HVDC and nuclear power. During the year 2008 the RCAM group was visited by Mauro da Rosa from INESC, Porto,Portugal. Two guest researchers are connected to the group i.e.: Dr. Stefan Arnborg (Svenska Kraftnät), and Prof. Michael Patriksson (Chalmers/Applied Mathematics),

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working part time 5-20%. Associate Prof. Lina Bertling was on part time leave for a position at Svenska Kraftnät. Three master theses projects were concluded within the RCAM group during 2008, closely related to the ongoing research projects. The reference group for RCAM involves around 20 participants from the industry closely related to the ongoing research work. The RCAM group had two strategy days in June to plan for future work. The strategy days where held at a training center in Åsbro, run by Svenska Kraftnät. Research results were presented in several journal and conference papers and oral at international conferences. The group has been active in IEEE PES committees and in several steering groups at Elforsk and Svensk Energi. 4.7.1 Reliability centered asset management BERTLING, Lina (Associate Professor, Ph.D.) HILBER, Patrik (Post-doc, Ph.D.) This post-doctoral project aims to further develop the reliability-centred maintenance method, with the overall goal to optimise the maintenance achievements and support cost-effective strategies for power systems. The developed RCAM method is refined to further investigate the component reliability for a general application of the method, and by incorporating optimization methods to obtain the maximum asset value. The research within this area is made related to the ongoing PhD and MSc projects within the RCAM research group. (Sponsored by the Competence Centre in Electrical Power Engineering at KTH, EKC2 and KTH) 4.7.2 Life time modelling and management of transformers BERTLING, Lina (Associate Professor, Ph.D.) HILBER, Patrik (Ph.D.) (PhD student vacancy) The goal for this project is to develop a quantitative probabilistic model, based on both failure statistics and measurements, for the life time of a transformer component. First models for life time estimation of transformers and measurements techniques will be studied. Then an improved model will be developed. Finally the developed model will be implemented into a maintenance planning problem as input data for the RCAM system reliability analysis. During the first year of this project a comprehensive literature review was made studying failure data and failure causes of power transformers, access was given to the transformer population of E.ON. distribution, work was also performed within a master thesis project by Sabina Karlsson which focuses on developing statistical method

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for life time estimation based on results from Dissolved Gas Analyses. Vacant position for a Ph.D. student, recruitment will begin in early 2009. This project is related to project 4.3.2. (Sponsored by the Competence Centre in Electrical Power Engineering at KTH, EKC2) 4.7.3 Development of optimization methods for maintenance considering reliability and

costs BERTLING, Lina (Associate Professor, Ph.D.) HILBER, Patrik (Ph.D.) This project works toward an optimization method for the determination of the optimal balance between preventive and corrective maintenance with respect to customer interruptions and total maintenance cost. The project is a continuation of a previous reliability-centred maintenance project at the division. As a first step the project started with an analysis of the level of outsourcing for maintenance activities as a part of a process description of the maintenance routines for transmission and distribution networks. As a second step, toward the objective, methods for identification of component reliability importance in electrical networks were developed. The component reliability importance measures constitute a connection between component performance and the total system performance, which is a central aspect when building a maintenance optimization routine. During 2007 these indices were implemented into the reliability tool RADPOW. During a research visit to the research institute INESC Porto in Portugal (October 2005-March 2006) a framework for maintenance optimization was developed. The framework is built on the previously developed component reliability importance indices. Continuously application studies have been performed in order to confirm and further improve the developed methods. Lately work has continued for the network of Kristinehamn. Patrik Hilber presented his PhD thesis: Maintenance Optimization for Power Distribution Systems, April 18, 2008. Opponent Professor Lalit Goel, Nanyang Technological University, Singapore.

(Sponsored by the Elektra program) 4.7.4 Optimal maintenance management for wind power systems with aspect on

reliability and cost BERTLING, Lina (Associate Professor, Ph.D.) BESNARD, François (Ph.D student) The goal for this project is to develop methods for optimal maintenance management of wind power systems. An optimal maintenance plan implies to prioritize the right tasks, for the right components, and the right time to reach a total least cost for maintenance. The

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research project is a result from a pre-study on RCM for wind power systems performed within the RCAM group (2005-2006). A state-of-the-art study of the wind power maintenance problem has been carried on by visits at Smøla and Kalmar wind parks, discussions with Vattenfall and littérature studiess. Another activity was a master thesis project focusing on condition monitoring systems for gearbox performed at NTNU that was finalized in April 2008. One conclusion from the state-of-the-art and master thesis was the difficulty to develop a prognosis model using condition monitoring system due to a lack of failure data and understanding (industrial secret) and the difficulty to connect systematically vibration and failure modes. It was therefore decided to further focus on the maintenance optimization at a system point of view. A model was developed in collaboration with Chalmers to take advantage of low power production and corrective maintenance required in order to perform preventive maintenance activities at low costs. An article presenting the model has been submitted to the conference PowerTech 2009. The model will be further developed to be more realistic and flexible.

(Sponsored by Vindforsk ) 4.7.5 Modelling of power equipment reliability with special reference to the impact of

maintenance BERTLING, Lina (Associate Professor, Ph.D.) LINDQUIST, Tommie (Ph.D.) The project developed equipment reliability models, that can be used for maintenance optimisation in power systems. The project resulted in methods on input data for equipment reliability/maintenance models, systematic characterization of fundamental failure mechanisms, equipment reliability models for key components in the power system and application study results. The aim, of the first step of this project was to establish a relationship between the ageing of power system equipment and their failure rate. This aim was met by the studying of failure statistics, maintenance records, design test-results and by carrying out field measurements including the development of a method to relate thermography measurements of electrical contacts to failure rate. The second step aimed to relate the effect of maintenance on the failure rate. This step has been met by the development of general method for modelling the effect of maintenance on equipment reliability as well as an empirical study on the effect of maintenance on electrical contacts. Tommie Lindquist presented his PhD thesis: On reliability and maintenance modelling of ageing equipment in electric power systems, April 25, 2008. Opponent Professor George Anders, Professor University of Toronto, Canada.

(Sponsored by the Elektra program)

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4.7.6 Reliability and cost centred maintenance methods BERTLING, Lina (Associate Professor, Ph.D.) NILSSON, Julia (PhD student) The goal for this project is to further develop the reliability-centred asset management method RCAM. The project shall include both reliability and cost considerations, and be focused on the introduction of the maintenance planning methods in different organizations. Total cost for maintenance and production loss is investigated for different production systems like wind and nuclear power. Forsmark has been identified as a suitable place for an application study. One subsystem in the nuclear power plant is the feed water pump system. During the year maintenance data of feed water pumps at Forsmark have been analyzed and used in an opportunistic maintenance optimization model. The optimization model for maintenance of this system has been constructed together with Chalmers and a paper has been submitted to Power Tech 2009. The project studies total cost analyses as a part of RCAM. Within a master thesis project on wind power systems an LCC study was made to investigate the benefit of introducing condition monitoring systems for maintenance planning. This model will be further developed both related to Forsmark and the Ph.D. project within the RCAM group on wind power systems. The project is scheduled to deliver a Licentiate thesis in June 2009. (Sponsored by the Competence Centre in Electrical Power Engineering at KTH, EKC2) 4.7.7 Reliability modelling and design for complex power systems with special focus on

the effects of introducing HVDC BERTLING, Lina (Associate Professor, Ph.D.) SETRÉUS, Johan (PhD student) The goal for this project is the development and computer implementation of techniques, models and methods suitable for the assessment of reliability of complex power systems. The project shall investigate possible benefits and challenges introducing new techniques (e.g. HVDC) for the power system design. The final goals are models and computer implementations that can be used for reliability assessment of complex power systems, such as the transmission system. Work within this project is performed in close collaboration with Dr. Stefan Arnborg at Svenska Kraftnät. The focus during the year has been to develop a reliability method that quantifies the transmission system's capability to transfer active power. The result is each system component's risk to insufficient power transfer in critical sections of the system. The method is demonstrated on a common used reliability test systems for the transmission system. The results have been submitted for reviewing to one journal magazine and one conference.

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The project is scheduled to deliver a Licentiate thesis in April 2009. (Sponsored by the Competence Centre in Electrical Power Engineering at KTH, EKC2) 4.7.8 Risks in the electrical distribution systems with optimal maintenance management

and the effect of different regulatory models

BERTLING, Lina (Associate Professor, Ph.D.), main supervisor HILBER, Patrik (PhD), supervisor WALLNERSTRÖM, Carl Johan (PhD student, Tech. Licentiate) The goal for this project is to investigate consequences/risks when introducing different maintenance and project plans for electrical distribution systems. The project especially focuses on the effect of introducing optimal RCAM plans (RCAM is a quantitative method based on RCM, adjusted to electric power systems – the overall goal of the RCAM research group to develop). The project aims to investigate the long term effect expressed e.g. in availability of maintenance management taking account new different circumstances for the electrical distribution systems. These circumstances could for example be new techniques, new laws and regulations and more private operators. A new law from 2006 which makes it compulsory for every distribution system operator (DSO) to do an annual analysis of risk and vulnerability makes this project of even more current interest and importance. One of the consequences the project focuses on is to consider long term effects on the system reliability. In May 15, 2008, a licentiate thesis was presented within the project with the title: “On Risk Management of Electrical Distribution Systems and the Impact of Regulations”. The project is planned to continue until a PhD-exam, with the same financier and aim as previous. A current activity within the project is the collaboration with Fortum Distribution, Karlstad. The objectives of the collaboration are to investigate, evaluate and systematic describe the work with risk management at a Swedish Distribution System Operator and give input to the further develop work of risk management that is actual in Sweden. The main purpose is that the academic research and the electrical industry learn from each other with knowledge and experience to improve methods of project- and maintenance planning used in the industry. Carl Johan Wallnerström presented his licentiate thesis: On Risk Management of Electrical Distribution Systems and the Impact of Regulations, May 15, 2008: Opponent Professor Kjell Sand, SINTEF, Norway. (Sponsored by Elforsk, “Riskprogrammet”)

5 Publications and reports 5.1 Ph.D. theses

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[1] Jun Song, Electromagnetic simulation and design of etched diffraction grating demultiplexers, PhD Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[2] Mohsen Torabzadeh-Tari, DIMENSIONING TOOLS OF MEA ACTUATOR SYSTEMS,, PhD Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[3] Jörgen Ramprecht, Electromagnetic Waves in Media with Ferromagnetic Losses, PhD Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[4] Cecilia Forssén, Modelling of cavity partial discharges at variable applied frequency, PhD Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[5] Tommie Lindquist, On reliability and maintenance modelling of ageing equipment in electric power systems, PhD Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[6] Patrik Hilber, Maintenance Optimization for Power Distribution Systems, PhD Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

5.2 Licentiate theses [1] Carl Johan Wallnerström, On Risk Management of Electrical Distribution Systems and the Impact of Regulations, Licentiate Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008 5.3 Master theses [1] Zhihua Huang, Bingfeng Zhu, Semi-Passive RFID-transponder, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[2] Peng Lin, A design approach of magnetostrictive actuators for hydroacoustic transducers, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[3] Alexander Witte, Broadband antenna for ionospheric sounding, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[4] Rafed Ayou, Implementation of Hysteresis Models in COMSOL, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[5] Tahir Awan, Studies of material parameters in magnetic materials, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[6] Kashif Sarwar Rana, Further development and verification of a hysteresis model, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[7] Yaser Abedalla, FEM Modeling of Non-linear Electrical Field Grading for Rotating Machine Windings, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[8] Mohammad Numan Abu Dheim, Broadband Active Antenna, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

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[9] Mohammad Numan Abu Dheim, Broadband Active Antenna, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[10] Anders Kallur, Guided reconnection in order to minimize transients, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[11] Michele Lucente, Condition Monitoring System in Wind Turbine Gearbox, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[12] Jean-Raphaël Corvol, Renewing and Maintenance in Operating Conditions of Instrumentation and Control, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[13] Christophe Lallemand, Methodology For a Risk Based Asset Management, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

[14] Göran Semart, Condition assessment of a medium voltage cable network by insulation diagnostics and failure statistics, Master's Thesis, ETK, School of Electrical Engineering, Royal Institute of Technology (KTH), Stockholm, 2008

5.4 Books [1] Nelson Theethayi, Rajeev Thottappillil, Electromagnetic Field Interaction with Transmission Lines From Classical Theory to HF Radiation Effects, "Surge propagation and crosstalk in multiconductor transmission lines above ground," Advances in Electrical Engineering and Electromagnetics,, (pp. 23-78,) WIT Press, UK, 2008 [2] Nelson Theethayi, Rajeev Thottappillil, Electromagnetic Field Interaction with Transmission Lines From Classical Theory to HF Radiation Effects, "Surge propagation in multiconductor transmission line below ground," Advances in Electrical Engineering and Electromagnetics, (pp. 79-122,) WIT Press, UK, 2008 5.5 Articles in journals [1] Xin HU; Sailing HE, "New Transmission Lines of Negative Refractive Index Based on Periodically Loaded Negative-Impedance-Converted Inductors and Capacitors," The European Physical Journal Applied Physics, (nov) 2008

[2] J.-P. Cui; J. Yao; Xin Hu, Q.-L. Zhang, "New Broadband Zero Phase Shifter based on Negative Refraction Index Transmission Line," J.of Electromagn. Waves and Appl, vol. 22 pp. 2069-2075, (dec) 2008

[3] Chen XW; He Sailing; Choy WCH, "Highly efficient and tunable fluorescence of a nanofluorophore in silica/metal dual shells with plasmonic resonance," JOURNAL OF APPLIED PHYSICS, vol. 103, (no. 024301,), (jan) 2008

[4] A.Berrier Y.Shi J.Siegert S.Marcinkevicius Sailing He, S.Anand, "Impact of dry-etching induced damage in InP-based photonic crystals," PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE), vol. 6989, (jan) 2008

[5] Lou Fishman, Lars Jonsson, Marteen de Hoop, "Time Reversal Mirrors and Cross Correlation Functions in Acoustic Wave Propagation," AIP Conference Proceedings, Mathematical Modeling of Wave Phenomena pp. 21, (dec) 2008, To appear

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[6] Cecilia Forssén, Hans Edin, "Partial Discharges in a Cavity at Variable Applied Frequency Part 2: Measurements and Modeling," IEEE Transactions on Dielectrics and Electrical Insulation, vol. 15, (no. 6,) pp. 1610-1616, (dec) 2008

[7] Cecilia Forssén, Hans Edin, "Partial Discharges in a Cavity at Variable Applied Frequency Part 1: Measurements," IEEE Transactions on Dielectrics and Electrical Insulation, vol. 15, (no. 6,) pp. 1601 - 1609, (dec) 2008

[8] Dai DX; He SAILING, " Design of an ultrashort Si-nanowaveguide-based multimode interference coupler of arbitrary shape," APPLIED OPTICS, vol. 47 pp. 38-44, (jan) 2008

[9] Ou H; Chen B; Fu H; SAILING HE, "Microwave-photonic frequency doubling utilising phase modulator and fibre Bragg grating," ELECTRONICS LETTERS, vol. 44 pp. 131-133, (jan) 2008

[10] Chen XW; He S; Choy WCH, " Highly efficient and tunable fluorescence of a nanofluorophore in silica/metal dual shells with plasmonic resonance," JOURNAL OF APPLIED PHYSICS, vol. 103, (no. 024301,), (dec) 2008

[11] He GS; Qin HY; Zheng Q; SAILING HE, " Dynamic properties and optical phase conjugation of two-photon pumped ultrashort blue stimulated emission in a chromophore solution," PHYSICAL REVIEW A, vol. 77, (no. 013824,), (jan) 2008

[12] Zhang P; Jin Y; He SAILING, "Cloaking an object on a dielectric half-space," OPTICS EXPRESS, vol. 16 pp. 3161-3166, (mar) 2008

[13] Wang B; Shen LF; He SaiLing, "Superlens formed by a one-dimensional dielectric photonic crystal," JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS, vol. 25 pp. 391-395, (mar) 2008

[14] Dai DX; Yang L; He SaiLing, "Ultrasmall thermally tunable microring resonator with a submicrometer heater on Si nanowires," JOURNAL OF LIGHTWAVE TECHNOLOGY, vol. 26 pp. 704-709, (mar) 2008

[15] Ding JC; Lin ZL; Ying ZN; sailing he, "A compact ultra-wideband slot antenna with multiple frequency bands," MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, vol. 50 pp. 1446-1446, (may) 2008

[16] Yang L; Dai DX; He Sailing, "Thermal analysis for a photonic Si ridge wire with a submicron metal heater," OPTICS COMMUNICATIONS, vol. 281 pp. 2467-2471, (may) 2008

[17] Khan SN; Hu J; Xiong J, sailing he, "Circular fractal monopole antenna based on descartes circle theorem for uwb application," MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, vol. 50 pp. 1605-1608, (jun) 2008

[18] Zhu N; Dai DX; He SAILING, "A hybrid modeling for the theoretical analysis of reflections in a multimode-interference coupler based on silicon-on-insulator nanowires," OPTICS COMMUNICATIONS, vol. 281 pp. 3099-3104, (jun) 2008

[19] Geng YL; He SaiLing, "Spherical vector wave functions solution to scattering of a plane wave by a spherical shell of uniaxial anisotropic left-handed material," MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, vol. 50 pp. 2142-2146, (aug) 2008

[20] Ning Zhu;Jun Song; Lech Wosinski, Sailing He, "Design of a Polarization-Insensitive Echelle Grating Demultiplexer Based on Silicon Nanophotonic Wires," IEEE PHOTONICS TECHNOLOGY LETTERS,, vol. 20 pp. 860-862, (may) 2008

[21] Li X; Qian J; He SaiLing, "Impact of the self-assembly of multilayer polyelectrolyte functionalized gold nanorods and its application to biosensing," NANOTECHNOLOGY, vol. 19, (no. 355501,), (sep) 2008

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[22] Dai DX; He SaiLing, "Proposal for diminishment of the polarization-dependency in a Si-nanowire multimode interference (MMI) coupler by tapering the MMI section," IEEE PHOTONICS TECHNOLOGY LETTERS, vol. 20 pp. 599-601, (mar) 2008

[23] Chen JJ; Wosinska L; He SaiLing, "High utilization of wavelengths and simple interconnection between users in a protection scheme for passive optical networks," IEEE PHOTONICS TECHNOLOGY LETTERS, vol. 20 pp. 389-391, (mar) 2008

[24] Wang BW; Jin Y; He SAILING, "Design of subwavelength corrugated metal waveguides for slow waves at terahertz frequencies," APPLIED OPTICS, vol. 47 pp. 3694-3700, (jul) 2008

[25] Fang YT; He Sailing, "Transparent structure consisting of metamaterial layers and matching layers," PHYSICAL REVIEW A, vol. 78, (no. 023813,), (aug) 2008

[26] Hu Xin; He Sailing, "Novel diplexer using composite right/left-handed transmission lines," MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, vol. 50 pp. 2970-2973, (nov) 2008

[27] Shi YC; He SaiLing; Anand S, "Ultracompact directional couplers realized in InP by utilizing feature size dependent etching," OPTICS LETTERS, vol. 33 pp. 1927-1929, (sep) 2008

[28] Tang YB; Yu YC; Ye YQ ;Urban Westergren , Sailing He, "Design and optimization of an arbitrarily segmented traveling wave electrode for an ultrahigh speed electroabsorption modulator," OPTICS COMMUNICATIONS, vol. 281 pp. 5177-5182, (oct) 2008

[29] Fu H. Zhou K. Saffari P. Mou C. Zhang L. He Sailing. Bennion I., "Microchanneled Chirped Fiber Bragg Grating Formed by Femtosecond Laser-Aided Chemical Etching for Refractive Index and Temperature Measurements," IEEE PHOTONICS TECHNOLOGY LETTERS, vol. 20 pp. 1609-1611, (sep) 2008

[30] Fu HY; Ou HY; Kun Zhu Edvin Remb , Sailing He, "A tunable and reconfigurable microwave photonic filter based on two cascaded modulators and a dispersive medium," OPTICS COMMUNICATIONS, vol. 281 pp. 5550-5554, (nov) 2008

[31] He G. S.; Yong K.-T Qin H.-Y.; Zheng Q.; Prasad P. N.; He Sailing.; Agren H.;, "Stimulated Rayleigh–Bragg Scattering From a Two-Photon Absorbing CdSe–CdS–ZnS Quantum-Rods System: Optical Power Limiting and Phase-Conjugation," IEEE JOURNAL OF QUANTUM ELECTRONICS, vol. 44 pp. 894-901, (oct) 2008

[32] J Hu S. N. Khan J. Xiong , Sailing. He, "CIRCULAR AXE-SHAPED PATCH ANTENNA FOR COMPACT AND DUAL BAND WIRELESS APPLICATIONS," JOURNAL OF ELECTROMAGNETIC WAVES AND APPLICATIONS, vol. 22, (no. 1655-1660,), (dec) 2008

[33] Hu Rui Dai DaoXin, He SaiLing, "A Small Polymeric Ridge Waveguide With a High Index Contrast," JOURNAL OF LIGHTWAVE TECHNOLOGY, vol. 26 pp. 1964-1968, (aug) 2008

[34] Jörgen Ramprecht, Martin Norgren, Daniel Sjöberg, "Scattering from a Thin Magnetic Layer with a Periodic Lateral Magnetization: Application to Electromagnetic Absorbers," Progress In Electromagnetics Research, vol. 83 pp. 199-224, (jun) 2008

[35] Anders Ellgardt, "A Scan Blindness Model for Single-Polarized Tapered-Slot Arrays in Triangular Grids," IEEE Transactions on Antennas and Propagation, vol. 56 pp. 2937 - 2942, (sep) 2008

[36] David Ribbenfjärd, Göran Engdahl, "Novel Method for Modelling of Dynamic Hysteresis," IEEE Transactions on Magnetics, vol. 44 pp. 854-857, (jun) 2008

[37] Tommie Lindquist Lina Bertling Roland Eriksson, "Circuit Breaker Failure Data and Reliability Modelling," IET Generation, Transmission and Distribution, (nov) 2008

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[38] Surajit Midya, Rajeev Thottappillil, "An Overview of Electromagnetic Compatibility Challenges in European Rail Traffic Management System," Journal of Transportation Research Part C: Emerging Technologies, vol. 16C pp. 515-534, (oct) 2008

[39] Nag A., V. A. Rakov, W. Schulz, M. M. F. Saba, Rajeev Thottappillil, C. J. Biagi, A. Oliveira Filho, A. Kafri, N. Theethayi, T. Gotschl, "First versus subsequent return-stroke current and field peaks in negative cloud-to-ground lightning discharges," Journal of Geophysical Research, vol. 113 pp. D19112, (oct) 2008

[40] Flache D., V. A. Rakov, F. Heidler, W. Zischank, Rajeev Thottappillil, "Initial-stage pulses in upward lightning: Leader/return stroke versus M-component mode of charge transfer to ground," Geophysical Research Letters, vol. 35 pp. L13812, (jul) 2008

[41] Justinian Anatory; Nelson Theethayi; Rajeev Thottappillil; Mussa Kissaka, Nerey Mvungi, "Expressions for Current/Voltage Distribution in Broadband Power-Line Communication Networks Involving Branches," IEEE transactions on power delivery, vol. 23 pp. 188 - 195, (jan) 2008

[42] Justinian Anatory; Nelson Theethayi; Rajeev Thottappillil; Mussa Kissaka, Nerey Mvungi, "Broadband Power-Line Communications: The Channel Capacity Analysis," IEEE transactions on power delivery, vol. 23 pp. 164 - 170, (jan) 2008

[43] Justinian Anatory; Nelson Theethayi; Rajeev Thottappillil; Mussa Kissaka, Nerey Mvungi, "The Influence of Load Impedance, Line Length, and Branches on Underground Cable Power-Line Communications (PLC) Systems," IEEE transactions on power delivery, vol. 23 pp. 180-187, (jan) 2008

[44] Justinian Anatory; Nelson Theethayi; Rajeev Thottappillil; Mussa Kissaka, Nerey Mvungi, "An Experimental Validation for Broadband Power-Line Communication (BPLC) Model," IEEE transactions on power delivery, vol. 23 pp. 1380-1383, (jul) 2008

[45] Nelson Theethayi; Yoshihiro Baba; Farhad Rachidi, Rajeev Thottappillil, "On the Choice Between Transmission Line Equations and Full-Wave Maxwell's Equations for Transient Analysis of Buried Wires," IEEE Transactions on Electromagnetic Compatibility, vol. 50 pp. 347-357, (may) 2008

[46] Nelson Theethayi; Vladimir Rakov, Rajeev Thottappillil, "Responses of Airport Runway Lighting System to Direct Lightning Strikes: Comparisons of TLM Predictions With Experimental Data," IEEE Transactions On Electromagnetic Compatibility, vol. 50 pp. 660-668, (aug) 2008

[47] Nelson Theethayi; Rajeev Thottappillil; Gerhard Diendorfer; Martin Mair; Hannes Pichler, "Currents in Buried Grounding Strips Connected to Communication Tower Legs during Lightning Strikes," IEEE Transactions on Dielectrics and Electrical Insulation, vol. 15 pp. 1153-1161, (aug) 2008

[48] Daniel Månsson; Rajeev Thottappillil; Tony Nilsson; Olof Lundén; Mats Bäckström, "Susceptibility of Civilian GPS Receivers to Electromagnetic Radiation," IEEE Transactions On Electromagnetic Compatibility, vol. 50 pp. 434-437, (apr) 2008

[49] Daniel Månsson; Rajeev Thottappillil, Mats Bäckström, "Propagation of UWB Transients in Low-Voltage Power Installation Networks," IEEE Transactions On Electromagnetic Compatibility, vol. 50 pp. 619-629, (aug) 2008

[50] Daniel Månsson; Rajeev Thottappillil; Mats Bäckström; Olof Lundén, "Vulnerability of European Rail Traffic Management System to Radiated Intentional EMI," IEEE Transactions On Electromagnetic Compatibility, vol. 50 pp. 101-109, (feb) 2008

[51] Carl Johan Wallnerström, Lina Bertling, "Investigation of the Robustness of the Swedish Network Performance Assessment Model," IEEE Transactions on Power Systems, vol. 23, (no. 2,) pp. 773 – 780, (may) 2008, http://ieeexplore.ieee.org

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5.6 Conference proceedings [1] Mohsen Torabzadeh-Tari, Göran Endahl, "A Time Domain Frequency Separation, TDFS-Model Approach Including Reactive Power of a Novel Electromechanical Actuator for MEA Applications," ACTUATOR 2008, 2008

[2] Lars Austrin, Eduardo Figuroa Karlström, Göran Engdahl, "Evaluation of switching losses in magnetic amplifiers as an alternative to IGBT technologies," Praoceedings of PEMD, York, England, 2008

[3] Lars Austrin, "Electricity in the air," Technology transfer, Technologies within SAAB, 2008

[4] Rajeev Thottappillil, Daniel Månsson, Mats Bäckström, "Susceptibility of Electrified Railway Facilities to Intentional Electromagnetic Interference," RVK, 2008, RVK08, Växjö, June 9-11

[5] Raul Montaño, Mats Bäckström, Daniel Månsson, Rajeev Thottappillil, "Response and Immunity of Electric Power Infrastructure Against IEMI – Ongoing Swedish Initiatives," RVK, 2008, RVK08, Växjö, June 9-11

[6] Schulz W, Sindelar S, Kafri A, Götschl T, Theethayi N, Thottappillil R, "The Ratio Between First And Subsequent Lightning Return Stroke Electric Field Peaks In Sweden," 29th International Conference on Lightning Protection, 2008, Uppsala, June 23-26

[7] Rajeev Thottappillil, Daniel Mansson, Mats Bäckström, "Susceptibility of Electrified Railway to Intentional Electromagnetic Interference: Research in Sweden," European electromagnetics (EUROEM), 2008, Lausanne, July 21-25

[8] Surajit Midya, Dierk Bormann, Anders Larsson, Thorsten Schütte, Rajeev Thottappillil, "Pantograph Arcing and their Consequences to Electromagnetic Interference in Railway Systems," European electromagnetics (EUROEM), 2008, Lausanne, July 21-25

[9] Surajit Midya, Thorsten Schütte, Rajeev Thottappillil, "Interaction and Interference Between AC and DC in Railway Feeding Systems," European electromagnetics (EUROEM), 2008, Lausanne, July 21-25

[10] Nelson Theethayi, Ziya Mazloom, Rajeev Thottappillil, Per Anders Lindeberg, Thorsten Shutte, "Review of Research on Lightning Interaction with the Swedish Railway Network," European electromagnetics (EUROEM), 2008, Lausanne, July 21-25

[11] Ziya Mazloom, Nelson Theethayi, Rajeev Thottappillil, "Modeling of Passive Series Devices on Multiconductor Transmission Lines for Transient Analysis in Power and Railway Systems," European electromagnetics (EUROEM),, 2008, Lausanne, July 21-25, 2008

[12] Mats Bäckström, Rajeev Thottappillil, Daniel Månsson, Raul Montano, Olof Lundén, Tony Nilsson, "Some Recent Work on Intentional EMI in Sweden, European electromagnetics," Euro Electromagnetics (EUROEM), 2008, Lausanne, July 21-25, 2008

[13] Daniel Månsson, Rajeev Thottappillil, Mats Bäckström, "Propagation Ability of UWB Transients through Junctions of Low-voltage Power Installation Cable," 19th International Zurich Symposium on Electromagnetic Compatibility, 2008, Singapore, May 19 - 22,

[14] Nelson Theethayi, Rajeev Thottappillil, Gerhard Diendorfer, Martin Mair, Hannes Pichler, "Currents in Buried Grounding Strips Connected to Communication Tower Legs during Lightning Strikes," 2008 URSI General Assembly, 2008, Chicago, Illinois, USA, August 7-16

[15] Raul Montaño, Mats Bäckström, Daniel Månsson, Rajeev Thottappillil, "On the Response and Immunity of Critical Infrastructures Against IEMI – Current Swedish Research Initiatives," 19th

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International Zurich Symposium on Electromagnetic Compatibility, 2008, Singapore, May 19 - 22, 2008

[16] R. Thottappillil, N. Theethayi, T. Hågård, K. Sjöberg, U. Grape, "Security Assessment For Ringhals Nuclear Power Plant, Unit 1, With Respect To Lightning Strikes," Cigre Symposium, 2008, Paris, August 24-29

[17] Surajit Midya, Dierk Bormann, Anders Larsson, Thorsten Schütte, Rajeev Thottappillil, "Understanding Pantograph Arcing in Electrified Railways – Influence of Various Parameters," 2008 IEEE EMC Symposium, 2008

[18] Lars Jonsson, "The kernel condition of a linearized pseudo-relativistic Hartree equation, a numerical approach," AIP Conference Proceedings, Mathematical Modeling of Wave Phenomena, pp. 8, 2008, To Appear

[19] Anders Ellgardt, " Effects on scan blindnesses of an absorbing layer covering the ground plane in a triangular grid single-polarized tapered-slot array," Antennas and Propagation Society International Symposium, 2008 IEEE, 2008

[20] David Ribbenfjärd, Göran Engdahl, "Optimization of the geometrical selection of subsections in Cauer circuit models of laminated magnetic materials at high frequencies," Proceedings IEEE Conference on Electromagnetic Field Computations, 2008

[21] Tommie Lindquist Lina Bertling Roland Eriksson, "Preventive maintenance task prioritization for electric power system equipment," Int. Journal of Electrical Power and Energy Systems, 2008, Submitted

[22] Valentinas Dubickas, Hans Edin, "Dielectric model of water trees in an XLPE cable," International Symposium on Electrical Insulating Materials, 2008

[23] Hanif Tavakoli, Dierk Bormann, David Ribbenfjärd, Göran Engdahl, "Comparison of a simple and a detailed model of magnetic hysteresis with measurements on electrical steel," Electromagnetic Phenomena in Nonlinear Circuits - EPNC 2008, 2008

[24] Rujiroj Leelaruji, Johan Setréus, Gabriel Olguin, Lina Bertling, "Availability Assessment of the HVDC Converter Transformer System," Proceedings 10th International Conference on Probabilistic Methods Applied to Power Systems (PMAPS), 2008

[25] Johan Setréus, Lina Bertling, "Introduction to HVDC Technology for Reliable Electrical Power Systems," Proceedings 10th International Conference on Probabilistic Methods Applied to Power Systems (PMAPS), 2008

[26] Carl Johan Wallnerström, Jörgen Hasselström, Per Bengtsson, Lina Bertling, "Review of the Risk Management at a Distribution System Operator," , 2008, PMAPS 2008, Puerto Rico. http://ieeexplore.ieee.org

[27] Patrik Hilber, Lina Bertling, "Multiobjective Maintenance Policy for a Distribution System an Application Study," PMAPS 2008, 2008

[28] Daniel Sjöberg, Jörgen Ramprecht, Niklas Wellander, "Stability and causality of effective material parameters for biased ferromagnetic materials," 2008 URSI General Assembly, Chicago, USA, 2008

[29] Jörgen Ramprecht, Daniel Sjöberg, "On the amount of magnetic material necessary in broadband magnetic absorbers," IEEE Antennas and Propagation International Symposium, San Diego, USA, 2008

[30] Lars Jonsson, "A numerical approach to the kernel condition of a linearized pseudo-relativistic Hartree equation," The third International Conference on Mathematical Modelling of Wave Phenomena 2008, 2008

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[31] Tommie Lindquist, Lina Bertling, "Hazard Rate Estimation for High-Voltage Contacts using Infrared Thermography," Reliability And Maintainability Symposium (RAMS), 2008

[32] Lars Jonsson, "On passive RCS reduction for planar scatterers in a metal hull," Progress In Electromagnetics Research Symposium, 2008, Accepted

5.7 Reports

[1] Volker Bach, Juerg Fröhlich, Lars Jonsson (2008), 'Bogolubov-Hartree-Fock Mean Field Theory for Neutron Stars and other Systems with Attractive Interactions', submitted

[2] Anders Ellgardt (2008), 'A study of edge effects in triangular grid tapered-slot arrays using coupling coefficients'

[3] Anders Ellgardt, Andreas Wikström (2008), 'A single polarized triangular grid tapered-slot array antenna'

[4] Lars Jonsson (2008), 'Wave splitting of Maxwells equations with anisotropic heterogeneous constitutive relations', submitted

[5] Jörgen Ramprecht, Daniel Sjöberg (2008), 'Magnetic losses in composite materials'

[6] Johan Setréus (2008), 'Verification of Results from the Loadflow module in RADPOW_2007'

[7] Lina Bertling (2008), 'The RCAM research group - history and status'

[8] Tommie Lindquist (2008), 'Estimating the accuracy of thermography of disconnector contacts in the field'

[9] Lina Bertling Patrik Hilber Jolanta Jensen Johan Setréus Carl Johan Wallnerström (2008), 'RADPOW development and documentation'

5.8 Miscellaneous [1] Martin Norgren (2008), 'Field Theory for Guided Waves', Course literature, Used in the course EI2410

[2] Göran Engdahl, Hans Edin, Martin Norgren, Staffan Rosander, Per Brunsell, Lars Blomberg (2008), 'Electrotechnical Modelling', Course material, Used in the courses EI2333 and EI2433

[3] Lars Jonsson, Staffan Ström (2008), 'Electromagnetic wave propagation and scattering', Course litterature, Material used by the students in EI2420

6 Conferences, courses and visits

January 28-31, Las Vegas Reliability and Maintainability Symposium (RAMS) T. Lindquist

February 4-5, 2008, Lund. Worskhop at LTH: Metamaterials and circuit analougs. L. Jonsson, M. Norgren.

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February 20-22, 2008, Jeju, Korea International Symposium on Convergence Technology “Using Polyelectrolytes to Functionalize Gold Nanorods for Bio-imaging and –sensing”, Sailing He (invited talk)

March 13, 2008, Access workshop, KTH L Jonsson

March 31-April 4, Chalmers, Göteborg Research visit F.Besnard, J. Nilsson

April 2-4, 2008, York, GB Power Electronics, Machines and Drives (PEMD 2008) L. Austrin April 9, 2008, Copenhagen NORKAB meetin H. Edin

May 7-9, 2008, Marrakesh – Morocco Workshop: Metamaterials for Secure Information and Communication Technologies, Xin HU

May 11-15, 2008, Athens, Greece Conference on Electromagnetic Field Computations (CEFC 2008) D. Ribbenfjärd

May 24, 2008, KTH Electromagnetic Workshop between LTH/KTH Organised by Lars Jonsson

May 25-29, 2008, Rincón, Puerto Rico Probabilistic Methods Applied to Power Systems , PMAPS 2008 F. Besnard, J. Nilsson, P. Hilber, J. Setreus, C. J. Wallnerström, L. Bertling.

June 2-3, 2008, Arlanda Vattenfall Cable Days H. Edin

June 11-12, 2008, Åsbro, Sweden Study visit at an electric transmission training centre owned and used by the Swedish National Grid (Svenska kraftnät), combined with a RCAM seminar and planning meeting. L. Bertling, F. Besnard, P. Hilber, J. Nilsson, J. Setréus and C. J. Wallnerström.

June 19-21, 2008, Korea University (Sejong), Korea Asian Symposium on Organic Materials for Electronics and Photonics “Organically Modified Silica Nanoparticles as Probes for Cancer Cell Imaging” Sailing He (invited talk)

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June 9-13, 2008, Växjö. RVK 08 Radiovetenskap och kommunikation, MMWP08 Conference on Mathematical Modelling of Wave Phenomena L. Jonsson, M. Norgren

July 1-5, 2008, Cambridge, USA Invited talk on Passive RCS Reduction for Planar Scatterers in a Metal Hull L Jonsson

July 2-4, 2008, Lille, France Electromagnetic Phenomena in Nonlinear Circuits (EPNC) H. Tavakoli

July 5-10, 2008, University of Toronto Research visit L Jonsson

July 5-11, 2008, San Diego, USA. IEEE Antennas and Propagation Society International Symposium A. Ellgardt, J. Ramprecht, A Motvasselian, A Lang

June 9-11, 2008, Bremen, Germany ACTUATOR 2008 M. Torabzadeh-Tari

July 20-24, 2008, Pittsburgh, USA 2008 PES General meeting. P. Hilber, L. Bertling.

August 23-25, 2008, Theran, Iran Invited lecturer at the 4th International Physical Aset Management Conference (IPAMC), Theran, Iran, 23-25th August, 2008. L. Bertling

August 25-29, 2008, Paris, France Participation at the Cigré Session 2008. L. Bertling

September 7-11, 2008, Yokkaichi, Mie, Japan International Symposium on Electrical Insulating Material V. Dubickas

September 8-9, 2008, Lund MIMO workshop on antenna systems at LTH L Jonsson

September 18, 2008, KTH The kick-off conference of AM3 was held at the department with visitors from LTH, China and industry representatives from SonyEricsson and Ericsson AB Organised by L Jonsson

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Sept 21-26, 2008, Pamplona, Spain Second International Congress on Advanced Electromagnetic Materials for Microwaves and Optics, “Some backward wave structures for slow light and light wheels “ Sailing He (invited talk)

October 22, 2008, Trondheim NORKAB meeting H. Edin

October 23-24, 2008, Gåshaga Bi annual LTH-KTH meeting Organised by Martin Norgren

October 6-16, 2008, Theoretical Physics Department ETH Research visit L Jonsson

November 17, 2008, ABB Corprate Research,Västerås Presentations of the research the activities at the department and discussions regarding further collaboration R. Thottappillil, G. Engdahl and H. Edin

December 5, 2008, Linköping. Workshop at FOI: Mikromodellering, beräkning av effektiva egenskaper för radarabsorberande kompositer. M. Norgren

7 Seminars and lectures 7.1 Seminars and lectures at KTH

February 12, KTH Docentlecture “Reliability theory with applications to preventive maintenance of the electric power system – with a case study for life time modelling of the power transformer component” L. Bertling

February 13-14 + March 11, 2008, KTH Lecturers for STF Ingenjörsutbildning AB C. J. Wallnerström

March 10 + May 16, 2008, KTH Presentations by Jörgen Hasselström, Fortum Distribution, C.J. Wallnerström, J. Setréus, P. Hilber, J. Nilsson, J. Setréus.

April 4, 2008, KTH Master thesis seminar. Three master thesis within the RCAM reaserch group were presented. L. Bertling, F. Besnard, P. Hilber, J. Nilsson, J. Setréus and C. J. Wallnerström.

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April 22, 2008 Seminar on Electrotechnical modelling at ABB Corporate Research, Västerås, Sweden G. Engdahl

May 7, 2008 KTH, Stockholm Seminar at KCSE, KTH Computational Science and Engineering Centre. Higher order optimization methods for inverse scattering with applications to microwave tomography. M. Norgren

May 19, 2008, KTH Seminar, with guest researcher Mauro da Rosa, INESC Porto, Portugal. L. Bertling, F. Be

October 22, 2008 Seminar on “Sum rules and fundamental bounds in scattering theory” 22/10 2008 Christian Sohl LTH

Automn 2008 Lectures in KTH course “Computational Electromagnetics”. Sailing He

7.2 Seminars given outside KTH

January 24, 2008, Stockholmsmässan Invited panel speaker at a seminar on Inviting the whole world – sharing experience from organizing an international conference in Stockholm, arranged by the Stockholm Visitor Board. L. Bertling

January 25, 2008, Tällberg

Invited guest lecturer at winter school by Syntell and at the course on logistics with presentation on “Examples on reliability assessment and maintenance management for the electric power system”. L. Bertling

January 31, 2008, Ludvika Invited speaker at the two days STRI conference with talk on: “What are the methods for assuring reliability and economics for electric power systems” L. Bertling

February 11, 2008, Prague, Czech Republic Invited speaker at the 2nd Annual Asset Management for Utilities Forum, Arranged by Marcus Evans. L. Bertling

May 26, 2008, Rincón, Puerto Rico Invited lecturer of a, half day tutorial on “Life time estimation for electric power components” presented at the 10th PMAPS L. Bertling

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September 23, 2008, Ludvika Invited presentation at the 7th Simpow User Group Meeting, STRI J. Setréus

May 13, 2008, British Embassy, Stockholm Invited speakers, Elforsk Maintenance Seminar. P. Hilber, T. Lindquist, L. Bertling

May 26-29, 2008, Nanjing, ChinaOSA (Optical Society of America) Topical Conference on Nanophotonics Sailing He (plenary talk): “Improving the performances and functionalities of photonics devices with subwavelength structures and nanoparticles”,

August 24, 2008, Theran, Iran Invited lecturer of a full day course with workshops on “Life time estimation for electric power components” and “Risk assessment for electrical distribution Systems”, at the 4th IPAMC. L. Bertling

Oktober 14, 2008, Stockholm, Sweden Elforskdagen "On-line diagnostic methods for power cables" V. Dubickas

November 5-7, 2008, Cheongpung Resort, Jecheon, Korea Photonics Conference 2008 Sailing He (plenary talk): “Improving the integration density and functionalities of photonics devices with subwavelength structures and nanoparticles”,

8 Other activities 8.1 National assignments Lars Jonsson, Peter Fuks, Martin Norgren. Participatation in a series of industry discussions with Ericsson Research. L. Austrin. Technical Fellow in Electrical Power Systems at Saab Aerosystems L. Austrin participated in Electric Power Board meeting, Chalmers, Gothenburg, March 11. L. Bertling. Member of UTEK Swedish Maintenance Society. L. Bertling. Member of the board of Swedish Society for members of parliament and researchers (RIFO). L. Bertling. Member of the Swedish standard association and the working group TK56 for the Swedish reliability standards. L. Bertling. Member of the steering group of IEEE Sweden Section until spring 2008, and has acted as secretary from 2006. L. Bertling. Member of the Royal Swedish Academy of Engineering Sciences (IVA), Section I, and the Industrial Research Group (IFG) during 2007-2009. L. Bertling. Member of a working group in the IVA project “Vägval Energi”.

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L Bertling. Member in the evaluation committee for the Ph.D. dissertation and thesis on “Wind power – added value for network operation” by Nayeem Rahmat Ullah, Chalmers, Monday December 15, 2008. L. Bertling. Member in the evaluation committee for the Ph.D. dissertation and thesis on “Maintenance performance indicators (MPIs) for railway infrastructure; identification and analysis for improvement” by Thomas Åhrén, Luleå University of Technology, Tuesday May 6, 2008. G. Engdahl, Member of the reference group for the Electra project “Equivalent circuit based solver for electromagnetic analysis of power electronic systems -application to IGBT modules R. Eriksson. Member of the board of the School of electrical engineering, KTH R.Eriksson. Chairman of selection committee for new dean of School of Electrical Engineering R.Eriksson. Expert evaluation for two associate professors at Uppsala University R. Eriksson. Member of Elektra review committee R. Erikson. Member of the Swedish national committees of Cigré and Cired . P. Hilber, Steering committee member of Advanced Vocational Education on Wind Power Operation and Maintenance. Hjalmar Strömerskolan, Strömsund, Sweden. P. Hilber Manager for the research program on Maintenance management of the Competence Centre in Electric Power engineering EKC2 with a yearly budget of around 6MSEK. Martin Norgren was one of the recievers of the ”En fjäder i hatten”-award from the students in engineering physics, ” for well structured and good lectures. 8.2 International assignments A. Ellgardt. Reviewer for IEEE Transactions Antennas and Propagation (one paper) L. Bertling. Reviewer for the following journals: International Journal of Electrical Power and Energy System, Electric Power Systems Research, IET Generation, Transmission & Distribution (previously IEE), IEEE Transactions on Power Delivery, IEEE Transactions on Power Systems, and IEEE Transactions on Energy Conversion. (Approximately 2-4 papers for each journal yearly.) L. Bertling. Reviewer for the following periodical conferences with referee system: The IEEE PES general meeting (yearly), The International conference on probabilistic methods applied to power systems (PMAPS), Power System Computational Conference (PSCC), and The IEEE Power Tech conference. (Approximately 5-10 papers for each conference, every second yearly (except for IEEE PES GM which is yearly).)

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L. Bertling. Member of the PMAPS International Society as chairman of the PMAPS2006 conference, and as a member of the International Technical Advisory Committee for PMAPS2006 and 2008. Responsible for the selection of host of PMAPS2010. L. Bertling. Member, and Secretary, in the Reliability Risk and Probability Applications Subcommittee of the IEEE Power Engineering Society, is chairman of a Task Force on Distribution systems reliability. L. Bertling. Member of the International Advisory Committee (IAC) of the IEEE PowerTech´09 in Bucharest, 2009. L. Bertling. Member of the Technical Programme Committee (TPC) of the Power Systems Computation Conference (PSCC) in Glasgow 2008. L. Bertling. Member of: IEEE Power Engineering Society, IEEE Reliability Society, IEEE Standard Society and IEEE Sweden Section. L. Bertling. Member of the evaluator pool for the EU commission. Engaged in evaluations of projects within the 6th research Framework Programme (FP), and review of proposals for the 7th FP. L. Bertling. Member of Cigré. H. Edin. Reviewer of 4 papers in IEEE transactions on Dielectrics and Electrical insulation. H. Edin Reviewer of 2 papers in IET Generation, Transmission and Distribution H. Edin Revwewer of 1 paper in Measurement Science and Technology H. Edin Reviewer of 1 paper in Journal of Physics D: Applied Physics H. Edin Reviwewer of 6 abstracts for IEEE Power Tech Conference H.Edin. Member of NORKAB H. Edin, Member of Nord-Is advisory committee G. Engdahl. Reviewer for AIP Magnetisn and Magnetiv Materials (one paper) G. Engdahl was assigned by the COMPEL referee database to be available to review manuscripts for the Journal for Computation and Mathematics in Electrical and Electronic Engineering which fall within his area of expertise R. Eriksson. Reviewer of 4 abstracts for IEEE Power Tech R. Eriksson. Reviewer of the journal IET Generation, Transmission and Distribution R.Eriksson Member of the IEEE Power Tech Conference steering committee. Sailing He.Topical Editor for Optics Letters since 2008. Sailing He. Fellow of SPIE (The International Society for Optical Engineering) Sailing He. Editorial Board member for Journal “Waves in Random and Complex Media” Sailing He. Guest Editor for Special Issue on Optical MEMS and Nanophotonics in IEEE Journal of Selected Topics in Quantum Electronics. Sailing He. Council member of OSA MES (Member & Education Services) since 2008. Sailing He. General Chair for the Asia Optical Fiber Communication & Optoelectronic Exposition & Conference (AOE) 2008 (co-sponsored by IEEE LEOS and OSA; Shanghai, China, October 31-Nov 2, 2008). Sailing He. Technical Program Chair for IEEE/LEOS International Conference on Optical MEMS and NanoPhotonics 2008 (Freiburg, Germany, 11- 14 August, 2008)

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Sailing He. Reviewer of over 20 papers last year for international journals such as Nature Photonics, Physical Review Letters, IEEE Journal of Lightwave Technologies, IEEE Transactions on Antennas and Propagation. L. Jonsson. Review for Discrete and Continuous Dynamical Systems M. Norgren. Reviewer for Journal of Electromagnetic Waves and Applications 8.3 Mobility Christian Sohl from Lund University visited the department during the autumn of 2008 Lina Bertling was on part time leave for a position at Svenska Kraftnät from September 2007, and was appointed Research Director at Svenska Kraftnät in June 2008. Mauro da Rosa, from INESC Porto, Portugal visited the RCAM group April-June 2008. Stefan Arnborg from Svenska Kraftnät, and Michael Patriksson from Chalmers were engaged in the activities of the department during the year. Sailing He is 50% engaged as research leader in Joint Research Centre of Photonics between Zhejiang University, China and KTH. The joint research includes Ph.D. students and Post Docs at both universities. Dierk Borrmann from ABB Corporate Research, Stefan Arnborg from Svenska Kraftnät, Erik Dotzauer from Fortum and Michael Patriksson from Chalmers were engaged in the activities of the department during the year.