DTU Electrical Engineering in Pro! le 2010 DTU Electrical Engineering in Pro! le 2010

Editorial function: Bettina Bork & Kristian Stubkjær

Photography: Birgitte Sundwall, Sonja Iskov, Lasse Rusborg, Colourbox, Lars Bahl, Peter Ho! mann, " orkild Amdi Christensen, Evert J. Friberg-Jensen, Lars Skaaning

Cover: Electronics, photo Mikkel Adsbøll Reproduction and printing: Brande Bladet Design: Artcome

DTU Electrical Engineering Technical University of Denmark Ørsteds Plads, building 349 DK-2800 Kgs. Lyngby www.elektro.dtu.dk E-mail: [email protected]

ISBN: 978-87-92465-29-0 Contents

Introduction ...... 2

Facts and ! gures ...... 3

PhD projects ...... 4

Awards, honours and appointments ...... 42

Public outreach ...... 44

Advisory board ...... 48

Management ...... 48

Publications ...... 48

Links ...... 48

1

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Introduction

We are happy to present this pro! le magazine 2010 that re" ects our many research ! elds and activities.

DTU Electrical Engineering is the central department at DTU within electrical engineering, within bio-medical engineering and within our new ! eld of playware. We experience an enormous interest in our activities from the world round us including many new students. # is is clearly emphasising the relevance of the activities for society:

• # e health sector and the biomedical industry rely on our activities in hearing technology, ultrasound imaging and the increasing number of activities in a wide range of biomedical engineering and technologies for diagnosis of diseases • Activities in playware also address health issues and therapeutics via play as well as the well being of people of all ages. # e area supports the growth of a new industry • We engage in future electric energy systems including the intelligent grid which is crucial for Denmark to achieve 30 % renewable energy in 2020 • Our world leading activities on energy saving solutions in electric power systems, power electronics and automation and control are of importance to both industry and private households • Our expertise on antennas and microwaves is used in activities ranging from telecommunications and sensing to the new topic of body area networks • # e traditionally strong acoustics industry in Denmark is relying on our expertise and our candidates in the ! eld of electro-acoustics and building acoustics.

We are delighted to be a very popular choice for the students of DTU which is re" ected in full uptake on our three bachelor programs. At the same time the number of students on our master programs has nearly tripled during the last couple of years. We strive to maintain high standards regarding the student training and have recently renewed our bachelor programs. Much of our project oriented training is in collaboration with industry. O$ en solutions derive from student projects, and our research projects ! nd their way into new products. We are happy that our students are in high demand.

A considerable part of our research activities are linked to PhD projects. Currently we have about 70 PhD projects in the department; many are sponsored or conducted in collaboration with industry. We have chosen to concentrate this pro! le magazine on our PhD projects in stead of giving detailed descriptions of the activities in our sections. If you are interested in further details of our activities you are welcome to contact us. We hope you will enjoy reading this pro! le magazine.

Professor Kristian Stubkjær Head of Department

2

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Facts and ! gures

Income 2008 2009 Expenses 2008 2009

External funds 33,826 37,489 Salaries 62,921 77,127 Industrial/commercial 1,070 1,433 Operational costs 22,240 19,071 DTU funding 60,242 68,699 Total 85,161 96,198 Total 95,138 107,621

60,000 80,000 45,000 30,000 40,000

in 1000 DKK 15,000 in 1000 DKK 0 0 External funds Industrial/commercial DTU funding 2008 2009 2009 37,489 1,433 68,699 Salaries 62,921 77,127

2008 33,826 1,070 60,242 Operational costs 22,240 19,071

Total sta! * 2008 2009 Education 2008 2009

Faculty sta" 40 40 Graduated MScEE 79 80 Externally ! nanced 22 35 Graduated Bachelor EE 38 35 PhD students 45 68 Student f.t.e.*(value added) 414 370 Tech/Adm sta" 38 41 * f.t.e.=full time equivalent (årsværk) Total 143 184

* f.t.e.=full time equivalent (årsværk)

70

60

50 450 40

30 300

20 150 10 full time equivalent 0 0 Faculty sta! Externally PhD Tech/Adm Graduated Graduated Student "nanced students sta! MScEE Bachelor EE f.t.e.*(value added)

2009 40 35 68 41 2009 80 35 370

2008 40 20 45 38 2008 79 38 414

3

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 ACOUSTIC TECHNOLOGY Head of group: Associate Professor Finn Jacobsen

he research activities at Acoustic Technology may be divided into electro acoustics, physical acoustics, and architectural Tacoustics. In what follows a few examples of the group’s research activities from 2009 have been singled out. Some important acoustic transducers, e.g. loudspeakers, are inherently weakly nonlinear. If the nonlinearities are su% ciently well understood and the important parameters are known, the unwanted distortion can be removed using nonlinear control theory. Unfortunately, parameter dri$ is a serious problem with ordinary loudspeakers. Our research indicates that the problem of parameter dri$ is much less of an issue for the miniature loudspeakers in hearing aids, and there are reasons to expect that a nonlinear compensation technique can be successful.

A remarkably simple and powerful stochastic model for predicting measurement uncertainties in reverberation rooms has been developed by our group. # e model takes account of the phenomenon known as “weak Anderson localization”, and has so far been used successful in predicting the uncertainty associated with the sound power emitted in a reverberation room, and the uncertainty associated with the " uctuations in potential energy density, kinetic energy density, and sound intensity.

Statistical room acoustic models based on the concept of modal overlap in the frequency domain have been extremely successful for more than half a century, but similar considerations in the time domain have never led to convincing results. Our group, however, has developed a good model of the phenomenon based on the simple idea that not only does the re" ection density increase with time; the widths of the impulses are increased with each re" ection.

PhD Projects

Speaker’s comfort and increase of their voice level in lecture rooms

Vocal health is a major concern among teachers and represents a signi! cant cost for the school authorities. The physical environment of the teaching room – not only the background noise – plays a very important role in determining the average voice power levels at which teachers speak. When designing the acoustics of a classroom, one has to predict quantitatively the vocal e" ort that the teachers will experience, and regulations regarding classroom acoustics should take account of the voice levels needed to speak in classrooms to improve the teacher’s vocal health.

In this project a virtual auditory environment is used for determining the voice levels that teachers use in di" erent simulated classrooms under di" erent background noise conditions. Additional measurements are carried out in real classrooms during teaching activities. Physical measures of the classroom and of the sound ! eld are used to predict variations in the voice levels.

To be completed: 2011

David Pelegrin Garcia

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Modeling structural acoustic properties of loudspeaker cabinets

Modern loudspeaker systems are becoming increasingly complex. Consequently, the design engineers have to face the fact that unwanted structural acoustic problems may occur unexpectedly after a pre-production prototype has been manufactured and tested. Such problems are usually solved ad hoc at a late stage and may involve excessive costs to the modi! cation of production tools. Thus, prediction techniques are becoming more and more important.

The objective of this project is to develop new techniques for predicting the structural acoustic properties and forced vibration response of loudspeaker cabinets of irregular geometry. More speci! cally, the goal is to develop a theoretical/numerical model that can simulate the mechanical and structural acoustic properties of a loudspeaker cabinet of any given geometry and predict the vibration in the low to mid frequency range.

To be completed: 2011

Yu Luan

Sound source identi" cation using near " eld acoustic holography

Near ! eld acoustic holography is a sound source identi! cation technique that makes it possible to visualize the sound ! eld in the near ! eld of a source. It is particularly useful for studying complicated sound generation mechanisms. The technique involves measuring the sound ! eld in a two-dimensional aperture near the source under test. Based on this measurement, the three-dimensional sound ! eld near the source can be reconstructed. The resulting visualization can provide valuable information about the source mechanism.

This project studies di" erent techniques, their performance, limitations and applicability to di" erent cases. It is of particular interest to investigate holography based on measurement of the particle velocity. This is due to the fact that kinetic energy dominates in the evanescent near ! eld of the source. Moreover, it seems that the combination of sound pressure and particle velocity measurements can overcome some of the limitations of existing methods.

To be completed: 2012

Efrén Fernández Grande

Investigation of internal feedback in hearing aids

Modern hearing aids are met with demanding aesthetic requirements such as minimal physical size and visibility. The loudspeaker and the microphones are thus placed closely together. Consequently, problems with the transmission of sound and vibrations from the loudspeaker to the microphones easily occur. This causes a feedback problem, and limits the obtainable ampli! cation and therefore represents a critical design problem.

The feedback problem has been investigated by developing a full 3D-model of a behind-the-ear hearing aid. The model simulates the vibro acoustic transmission from the loudspeaker to the microphones. The hearing aid skeleton is based on ! nite element analysis, whereas the internals are modeled using the alternative theory of ‘fuzzy structures’. Simulations show a close agreement with electro-acoustic measurements on the actual hearing aid.

Completed in March 2009

Lars Friis

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 New strategies for feedback suppression in hearing instruments

For a long time unwanted feedback has been one of the major problems for users of hearing aids. Feedback occurs when part of the ampli! ed sound leaks from the ear canal and is picked up by the hearing aid microphone and then re- ampli! ed. Unchecked feedback can lead to system instability limiting the maximum stable gain that can be achieved in hearing aids. The user experiences feedback as a very unpleasant loud whistling or howling sound.

The purpose of the project is to examine and develop new ways of improving feedback suppression techniques in hearing aids. The new approaches include de-correlation techniques and new models for feedback paths. The project involves both computer simulations and laboratory experiments. A breakthrough in feedback suppression will bring better comfort to the hearing-aid users and improve the design of the current hearing aids.

To be completed: 2010

Guilin Ma

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 7

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 AUTOMATION AND CONTROL Head of group: Associate Professor Ole Ravn

e conduct research and teaching within methods and technologies for control and supervision of industrial systems Wincluding robotics and process plants. # e competences and work areas of our group include modelling and control of discrete and continuous dynamic systems, fault-tolerant control and diagnosis, sensor fusion, mobile robotics, applications of agents and knowledge-based systems in automation and decision-support systems for plant-wide diagnosis. Our research is focused on methods and technologies which can increase the availability, reliability and safety of industrial systems and processes.

Our group has established a successful cooperation with energy and process industries and the transport sector through industrial PhD and MSc projects as well as with Centre for Electric Technology (CET) and other research groups at DTU. Internationally we have cooperation agreements with NTNU, Trondheim, and Institute for Energy Technology, Halden, Norway and Harbin Engineering University, China. Furthermore, we exchange PhD and MSc students with numerous universities in Europe and USA. # e ongoing development of a mobile robot control system was successful when negotiating a second license for the so$ ware with a Danish company.

In 2009 we successfully initiated the AutomationDESIGN Centre. # e centre is a gateway for industry and other external partners for cooperation with DTU within the ! eld of industrial automation and control and to promote cooperation between DTU Electrical Engineering and other groups and centres at DTU within the area. Currently the centre is conducting a pilot project with three leading Danish industries and several PhD projects are in preparation.

PhD Projects

Robust and reliable robot operation in semi-structured environments

The ! eld of robotics is currently very mature for operation in structured environments, such as an assembly line. However, a much wider range of applications require the ability to cope with semi-structured environments, where not everything is controllable or known. This occurs when there are living beings in the environment, or the environment itself is too large or complex to model accurately.

This project aims at using advanced sensors with recent arti! cial intelligence methods to enable robust and reliable robot operation in semi-structured environments. Robot localization, recognition of task-related objects and environment mapping, main challenges of this ! eld, are in focus of this project. Robot vision is central to the approach due to its large information content and relatively lower cost, but other sensors will also be used to support it.

The results are expected to bene! t the society through enabling the use of robots for many tasks that require human labour today.

To be completed: 2012 Enis Bayramoðlu

8

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Situation assessment for mobile robots

In scienti! c and popular literature, the emergence of intelligent service robots outside of laboratories has been predicted repeatedly for the last 10 years. Yet we still do not see intelligent service robots in our homes, in our workplace or at the shopping malls. The reason is that reliable operation in dynamic and indeterministic environments is a huge challenge, not only for the navigation systems but also for handling unplanned and even unexpected events.

In cooperation with the Danish Technological Institute, the project aims at developing methods and techniques for situation assessment for mobile robot systems in general. By understanding the situation of a robot, unexpected errors can be resolved or even avoided. Based on signal processing, sensor fusion and arti! cial intelligence (AI), the project will investigate how a general situation modelling framework and architecture can be developed and applied.

Commercial success of service robots relies on handling of errors in a new general sense. This project will contribute with methodology to make a robotic future one step closer.

Anders Billesø Beck To be completed in 2012

Fault-tolerant navigation using vision and computer-based learning

Automatic navigation systems are already revolutionising farming by cutting costs and increasing output. Vision is an enabling technology, as it allows increased automation through new applications. However, computer-vision systems regularly produce artefacts in the image processing that could seriously disturb the safe function if used in closed loop steering of an automated tractor.

The project aimed at using vision in new ways by applying learning-based algorithms to the problem of navigation. Also, it contributes to increase the tolerance to faults by fusing the vision with multiple sensors such as odometry and GPS and by integrating fault-tolerance in the vision algorithms themselves.

The project has provided knowledge and experience concerning structured approaches to the design of fault-tolerant vision systems. Further, the project has shown methods to provide better reliability of vision systems for outdoor use. It will result in a signi! cantly better product with regard to availability and safety, and results will be applied in products in the near future.

Morten Rufus Blas Completed: December 2009

Robust and fault-tolerant control for nonlinear hydraulic-mechanical system

This project examines the combination of fault diagnosis with robust control for nonlinear hydraulic-mechanical (NHM) systems. Focus is on fault-tolerant control for NHM systems with applications focused on o" shore equipment. The research is also relevant to machining plants, in robotics and for fatigue testing systems. Another objective is to integrate the control issues in the design of a hydraulic-mechanical system. New ways of selecting hydraulic components will be investigated.

The project will investigate the usefulness of control methods in this specialised application, including passivity techniques in nonlinear control, adaptive back stepping, H-in! nity or mixed H_2 /H-in! nity controllers and fault- tolerant control. The interaction between controls, hydraulic system design and optimisation techniques will also be considered. The project aims at advancing the theory in nonlinear and fault-tolerant control, as well as validating the theory with experiments.

The results are anticipated to have a large impact on control performance and the reliability of hydraulic-mechanical systems. Martin Choux

To be completed: 2011

9

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Autonomous supervision and control of parametric roll resonance

Parametric roll is a resonance motion where large amplitude oscillations may develop in ships when the roll restoring moment varies in proportion with half of the roll eigenfrequency. Modern container ships are particularly prone to this due to their hull shape. The challenge is whether detection and stabilisation can be achieved in time to avoid damage.

In the project, stabilisation of parametric roll has been achieved directly, through increase of roll damping, or indirectly, through change in wave encounter frequency. Two control strategies - applying nonlinear Lyapunov-based methods - were combined to stabilise parametric roll within few roll cycles. Two novel detectors have been proposed, which work within a short-time prediction horizon, and issue early warnings of parametric roll inception within few roll cycles from its onset. The detectors have been validated against experimental data, and they have shown excellent performance and they have shown excellent performance in detection of the onset of parametric resonance.

The results are expected to be commercially interesting as ship-owners could avoid multi-million dollar damages every year if given the ability to avoid the roll resonance phenomenon. A proof-of-concept study has been started as Roberto Galeazzi a continuation of this research.

Completed: October 2009

Performance assessment and system monitoring for refrigeration systems

Supermarket refrigeration plants consume a large amount of energy. Consequently, it is bene! cial to operate the systems in the best possible way. However, optimal operation of a refrigeration plant is also dependent on other costs such as the replacement of components due to excessive wear. Thus, assessing the performance of the refrigeration plant is important to ensure optimal operation with respect to the total cost of ownership.

This project examines the possibility of establishing a performance measure for refrigeration systems including the control system. The development of algorithms to actively assess the performance of a distributed control system will be part of the project. In addition, automatic accommodation for the cause of the performance degradation of a control system by means of online retuning and/or redesign will be addressed.

The project focuses on the development of methods and tools for active performance assessment of refrigeration systems and algorithms for accommodation of performance degradation.

To be completed: 2011 Torben Green

Maintenance free and sustainable high-level control in cement and mining industry

The use of high-level control systems in cement plants is well established. It is acknowledged that they can improve performance by increasing production and reducing the environmental impact of the plant. In spite of this, many systems are taken out of use after a short period due to changes in the plant which are not handled by the control system. Therefore, the systems need regular adjustment by expert personnel to maintain a high performance.

Much research has focused on making the control algorithms top-performing and ever more tolerant to such changes. Modern control algorithms have therefore become sophisticated and complex pieces of software which are very di# cult to maintain. During this project, focus has turned onto the software aspects of control algorithms, and methods have been developed to monitor and diagnose the control algorithm rather than the plant.

In this way, an early warning is possible avoiding critical issues. Furthermore, man-hours for maintenance can be reduced by automatically locating the root cause of a problem.

Ole Fink Hansen Completed 2008, defended 2009

10

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Fault diagnosis and fault handling for autonomous airplanes

Small unmanned aerial vehicles have a great potential in many di" erent applications. However the relative simple components and control methods often used on this type of aircraft can be the cause of dangerous crashes. Safety and reliability considerations used on piloted airplanes cannot directly be used on smaller unmanned airplanes because of weight and space limitations, and therefore other methods must be considered.

This project investigates diagnosis of sensor and actuator faults for unmanned aerial vehicles. The goal is to create a system that is able to diagnose faults by analysing telemetry data while in the air. The airplane operator is noti! ed when a fault is discovered, and depending on the severity of the fault, appropriate actions are taken autonomously or suggested to the operator to bring down the plane in a safe manner and avoid hazardous situations.

Adding diagnosis systems to small unmanned aerial vehicles will make them able to complete their mission in a safer and more e# cient way and thereby enhancing their usability.

To be completed: 2012 Søren Hansen

Fault diagnosis for identi" cation of deviant behaviour in dairy cows

Automatic detection of deviant behaviour amongst dairy cows is a task of growing interest in modern farming. A main focus in this perspective is to detect deviant behaviour caused by oestrus or lameness. Early detection of a cow in oestrus or a cow su" ering from lameness can save the farmer from an economic loss and the animal from a prolonged period of pain/illness.

The main scope of this research is to study mathematical modelling of behaviour, extend methods from fault diagnosis and change detection to biometrical models for animal behaviour, and obtain a detection model. Methods of statistical change detection and automata-based detection theory are investigated, i.e. methods developed for fault diagnosis in industry but which can be modi! ed to cope with the complexity found with live animals.

This project results demonstrate how theory from technical sciences can be used within the much broader scope of biological detection problems and help aiding farmers’ decision making and Ensure the wellbeing of cows.

To be completed: 2010 Ragnar Ingi Jónsson

Nonlinear methods for spacecraft orbit control using an electrodynamic tether

An electrodynamic tether is a conducting cable used to induce a force on a spacecraft. The method utilises the Lorentz force, originating from the interaction between a current in the tether and the magnetic ! eld of the Earth, to change the orbit of the spacecraft. The method is particularly interesting in connection with the de-orbiting of obsolete satellites, but it can be used in general to perform corrections of orbit drift.

The objective of the project is to develop control strategies ensuring a stable motion of the satellite-tether system during orbit manoeuvres. The nonlinear dynamics of the system and the time-periodic variation of the magnetic ! eld during an orbit complicate the control problem and prevent the use of classical control methods, so novel control theory concepts are required.

This control approach permits orbit manoeuvring of a spacecraft independent of traditional propellant, but only by using electrical power obtained from its solar panels.

To be completed: 2010 Martin Birkelund Larsen

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 BIOMEDICAL ENGINEERING GROUP Head of group: Professor Jørgen Arendt Jensen

ur group is responsible for the BSc and MSc education in Medicine & Technology and conducts research into medical Oultrasound imaging, biomedical signal processing, physiological simulation, and cellular systems. We collaborate closely with many biomedical engineering companies and hospitals in Denmark. 2009 has been a very successful year for our group. # e number of applicants for the educations in Medicine & Technology was the highest since we started these educations. We obtained DKK 14.7 mio. from the Advanced Technology Foundation for the continuation of our Centre for Fast Ultrasound Imaging. Signi! cant sponsoring has also been obtained from BK Medical, the Copenhagen University Hospital (Rigshospitalet), and DTU. Funding for nine PhD projects to be started in 2009 was obtained from both industrial partners and from public sources.

Four PhD projects associated with the group were completed in 2009. # e ! rst ever clinical study of 3 ultrasound vector " ow techniques compared to MR phased contrast imaging was published in connection with Kr. L.Hansens’s project. H.Andresen’s project proved that synthetic aperture ultrasound imaging in three-dimension can be acquired with rotating and translating probes. # e bene! ts are an increased resolution, contrast, and penetration depth. K.S. Andersen’s project on pressure measurements with ultrasound contrast agents proved that bubbles are sensitive to pressure variations and that a new imaging system could be developed for visualizing the instantaneous pressure distribution. I.K. Holfort’s project on adaptive beam formation in ultrasound showed that these methods can increase the resolution of ultrasound images beyond the di& raction limit for super resolution.

PhD Projects

Experimental and theorectical investigation of signaling in quorum sensing of pseudomonas aeruginosa

The main focus in 2009 has been on the production of signal molecules in quorum sensing bacterial cells. These are very important for the bacterial system since the amount produced works as an indicator of how many bacteria are present. If a threshold value is met the bacterial cells attack its host system. Thus if the amount of signal molecules can be limited the bacterial cells are harmless.

Two strategies have been followed in the last year. The decay of the signal molecule N-butanoyl-L-homoserine lactone (C4-HSL) has been monitored and the results published in an article and a poster as co-author. Furthermore, the spectroscopic Raman technique, Surface Enhanced Raman Scattering (SERS), has been applied to the detection of the signal molecule N-Dodecanoyl-DL-homoserine lactone (C12-HSL) with success.

Concentrations below nano Molar was observed. This was presented as a poster at the ASM Bio! lm conference in Cancun, Mexico. The results are in preparation to be published.

Anetta Clausen To be completed: 2011

12

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Prediction and detection of epileptic seizures

Of the world’s population, 1% su" ers from epilepsy. Most of these patients can be treated out of their reoccurring seizures with existing medication or epilepsy surgery, but approximately 25% will continue to experience epileptic attacks. These unforeseen seizures are a cause of social stigma for the patients, and cause considerable demoralization, frustration and anxiety for themselves as well as family and friends.

Using the electrical signals from the brain, we look at the possibility of detecting, and perhaps even predicting, seizures. Instead of measuring at a hospital, we have developed a small portable device following the patient in daily life. The challenge is now to develop a dedicated automatic seizure detection algorithm, which uses a reduced number of electrodes compared to the hospitals’ systems, which often uses 16 or more.

In 2010 the ! rst clinical trials with absence epilepsy will start. Design and test of an algorithm for this patient group will be followed by additional work related to other patient groups.

To be completed: 2012 Jonas Henriksen

Protein dynamics simulations at millisecond time scales

Many proteins are highly dynamic and adopt di" erent states under physiological conditions. These conformational isomers hold the key to understand important biological processes (enzymatic catalysis, signal transduction, regulation and protein misfolding - Alzheimers, Parkinsons disease and type II diabetes). Standard computational tools result in inaccuracies of the force ! elds employed and sampling ine# ciencies.

The overall aim of the project is to develop a general computational method to elucidate the molecular mechanism of conformational switches. At the heart of the project is the use of a novel probabilistic, kinetic method, developed in our group at DTU Elektro overcoming the de! ciencies of current methodologies to protein dynamics. Our results will be corroborated against Nuclear Magnetic Resonance data, and possible discrepancies used to re! ne the force ! eld.

The method will be applied to understand fundamental mechanisms in enzymatic catalysis, and to identify the conformational states that trigger the protein aggregation process associated with misfolding diseases.

To be completed: 2012 Sandro Bottaro

Synthetic aperture compound imaging

Medical ultrasound imaging is used for many purposes, e.g. for localizing and classifying cysts and tumors. A major drawback of ultrasound imaging is the low contrast due to the presence of speckle artifacts. A successful approach to remedy this is spatial compounding, where images are acquired from di" erent directions and combined. The resulting images have a reduced speckle appearance, but at the cost of a reduced frame rate.

This project develops methods to perform spatial compounding using synthetic aperture data acquired with the experimental ultrasound scanner SARUS. It is investigated how to obtain a reduction in speckle appearance without a reduction in frame rate as well as how to increase the resolution using motion compensation. The methods are evaluated through phantom studies and in pre-clinical trials.

Synthetic aperture compounding should be able to obtain high contrast images allowing for an early detection of cysts and tumors.

To be completed: 2012 Jens Munk Hansen

13

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Non-linear ultrasound imaging

Non-linear ultrasound imaging is extensively used in clinics due to its improved image quality. It has been observed that the contrast is signi! cantly better. However, currently there is still a limited understanding of the inner workings of non-linear imaging. It is very di# cult to realistically simulate the non-linear propagation and often it is not understood why the non-linear images are better.

This project seeks to gain a detailed understanding of the non-linear propagation of ultrasound waves in the human body. The goal is sought accomplished through development of simulation software, measurements of ultrasound ! elds in water and on phantoms as well as pre-clinical trials to reveal the bene! ts of non-linear ultrasound imaging.

A clear understanding of non-linear ultrasound makes it possible to optimize the image quality, which can improve clinical diagnosis

To be completed: 2011

Yigang Du

Synthetic aperture # ow imaging using a dual beam former approach

Synthetic Aperture (SA) $ ow estimation has many advantages compared to conventional ultrasound imaging in as data can be acquired continuously for the full imaging region. The accuracy of estimates can therefore be very high and the frame rate can be increased because of the continuous data acquisition. It is also possible to ! nd the velocity in all directions and map out complex $ ow phenomena.

SA $ ow imaging requires a large number of calculations to be performed. The aim of this project is to develop a computationally e# cient method for synthetic aperture velocity estimation based on a dual beam former approach. The challenge is to lower the number of emissions and still maintain the quality su# cient for $ ow estimation. The approach will be developed and tested through simulations, phantom studies and an implementation for clinical tests on a commercial scanner.

Commercial implementation of a full SA ultrasound scanner capable of both anatomic and $ ow imaging, thus increasing the diagnostic value of ultrasound imaging by a higher accuracy and frame rate of velocity estimation systems.

Ye Li To be completed: 2012

3D vector # ow imaging

Medical ultrasound imaging is widely used for studying blood $ ow dynamics in the human circulatory system. However, blood velocity estimates using conventional techniques are angle dependent. This strongly limits the possibility of visualizing complicated $ ow patterns and obtaining the true velocity. This problem has been remedied by methods developed at Centre for Fast Ultrasound Imaging (CFU) at DTU Elektro for 2D velocity estimation.

The aim of this project is to develop a method for full 3D vector velocity imaging to correctly show the velocity vector. Methods for acquiring data and estimating the velocity are developed based on 2D techniques already developed at CFU with main focus on the transverse oscillation method. The methods will then be implemented on the experimental ultrasound scanner SARUS at CFU and evaluated on $ ow phantoms and human volunteers.

With 3D vector $ ow imaging, complex $ ow patterns can be visualized and, potentially, pathological $ ow patterns around occlusions, valves, and bifurcations can be identi! ed.

To be completed: 2012 Michael Johannes Pihl

14

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Diagnosis of heel pad injuries

Heel pad injuries, caused by fall accidents, marathon running, falanga torture etc., may cause the destruction of the heel pad intricate septation leading to permanent damage of its shock absorbency capability, and causing great pain for the patient, when trying to walk. Examinations are di# cult to carry out, since there are a number of confounding factors in$ uencing the result. One such factor is the natural variation in skin to heel-bone distance.

The objective is to obtain a quantitative evaluation of the heel pad tissue damage, and to gather information on the complete deformation of the heel pad tissues. A device based on an indentation experiment is to be developed. In order to achieve a description of the tissue damage at a microscopic level a computational simulation (FEM) of the heel pad is to be done. Such simulations will be validated by clinical studies.

Quantitative validated mechanical examination methods constitute pre-requisites for diagnosis and cure of heel pad diseases as well as medico-legal assessment for falanga torture.

To be completed: 2011 Sara Matteoli

Computational simulation of stent-graft based minimally-invasive aortic aneurysm repair

Aortic aneurysms are abnormal dilations on the aorta arising from a weakening in the musculature of the vessel wall. The cause of development of an aortic aneurysm is not completely understood. Among the risk factors are age, male gender, smoking and hypertension. The mortality of ruptured aneurysms is 85%. Most aneurysms are treated by placing a stent-graft in the aneurysm, sealing o" the fragile vessel wall to avoid rupture.

The objective is to develop a new ! nite element-based model of patient-speci! c aortic aneurysms for analysis and examination of critical parameters which are in evidence of the development and treatment of aneurysms. The in$ uence from these critical parameters on the risk of rupture is of speci! c interest.

The research will facilitate the identi! cation of patient-speci! c critical parameters related to rupture of aortic aneurysms, the prediction of rupture and simulation of the treatment.

To be completed: 2011 Marie Sand Enevoldsen

Calibrated modeling of ultrasonic " elds using Field II

The Field II program simulates ultrasound’s propagation in a linear medium. It uses the concept of spatial impulse responses to accurately model emitted, scattered and received ! elds in ultrasound imaging for transducer surface geometry, focusing, apodization and medium attenuation. It is employed for simulating point spread functions, conventional anatomic and $ ow imaging as well as new methods for vector $ ow imaging.

The project aims at using Field II to carry out a calibrated modeling of the ultrasonic ! elds in front of transducers. This includes combining the Field II software with accurate impulse responses of medical transducers, used in connection with imaging procedures, and comparing actual pressure measurements with simulations. Optimization of the calculation procedure of the spatial impulse responses from double curved transducer surfaces is another goal.

The project implements transducer models allowing you to predict the volt-to-surface acceleration impulse responses whereby simulation and measurements on the transducers will be in agreement.

To be completed: 2010 David Bæk

15

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Image processing in medical ultrasound

The requirement for new medical ultrasound image processing schemes is often stated as “not worse than…”. Comparisons are made visually, and they are largely based on experience, prejudice, lighting conditions, view angle etc. The improvement of medical ultrasound images relies on an understanding of the in$ uencing factors. By quantizing these factors, new processing algorithms can be developed improving the diagnostic value of ultrasound imaging.

The objective is to achieve an understanding of the most signi! cant factors in$ uencing image quality in medical ultrasound and to develop a semi-quantitative measure of image quality based on a series of pre-clinical trials. Once such a measure is developed, new processing schemes should be developed to improve the diagnostic value.

In the project, a series of processing schemes is implemented on commercial and research scanners as part of the development of a semi-quantitative measure of image quality.

To be completed: 2011

Martin Christian Hemmsen

Detection and surveillance of epileptic seizures with automatic multi-modal signal analysis

Today 25% of the patients su" ering from epilepsy cannot get free of seizures. The unawareness of when the next seizure sets in makes the patient very insecure. As the seizures mostly appear without premonition, the patients are unable to bring themselves to safety. An alarm system able to detect epileptic seizures would therefore be of great help. Whenever a seizure sets in, the patient could immediately get help from family or hospital sta" .

The objective is to design medical signal processing algorithms that are able to distinguish between epileptic seizures and normal movements. These algorithms should be based on data from Electromyography (EMG) and movement sensors containing 3D accelerometers, 3D gyroscopes and 3D magnetometers. The alarm system is thereby proposed to be a multi modal system making the seizure detection more reliable.

If the detection modalities respond with a high sensitivity and few false alarms, there will be a basis for developing an alarm system for the detection of epileptic seizures.

Isa Conradsen To be completed: 2011

Non-invasive ambient pressure estimation using non-linear ultrasound contrast agents

Local blood pressure measurements provide important information on the health of the human body organs and can be used to diagnose severe heart, lung and kidney diseases. The pressure is currently measured locally in arteries and organs by a pressure catheter. As this is an invasive technique, it is inconvenient for the patient, there is a risk of infection, and the catheter will inevitably introduce changes to the blood $ ow and, thereby, the pressure.

The purpose is to investigate the possibilities of combining the physical interaction between ultrasound and highly compressible contrast agents for detecting ambient pressure changes. An experimental measurement setup has been designed and initial laboratory experiments carried out. A theoretical simulation study has investigated the mechanisms responsible for optimizing the sensitivity of the estimation yielding two clear and novel trends.

A non-invasive, reliable approach to measure the human blood pressure locally would provide doctors with a new and convenient tool to diagnose diseases related to the blood pressure.

Klaus Scheldrup Andersen Completed: 2009

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 3D synthetic aperture imaging

Medical ultrasound has been used for decades as a non-invasive diagnostic tool for physicians. Ultrasound systems have moved from simple 2D systems showing a single slice to 3D systems allowing full organ visualisation. Conventional systems use a focused ultrasound beam to image a single well-de! ned line at a time, building the 3D volume one line at a time. This method is very time-consuming, limiting the system’s frame-rate.

To consider the limitation of focused transmissions, this project focuses on applying a new technique known as synthetic aperture focusing. This method has the potential of improving both the image quality as well as the frame- rate. The main focus is to improve the image quality of 3D volumes acquired by equipment which is also used for conventional 3D imaging.

The improvements will give a better visualisation of the organs allowing more accurate diagnoses. The image-quality and ability will be closer to e.g. X-ray CT, but without radiation.

Completed: 2009 Henrik Andresen

Adaptive beamforming in medical ultrasound

Ultrasound imaging is used for several diagnostic purposes and is perhaps most commonly known for fetus scannings. Ultrasound images are formed from a weighted sum of several measured signals. The signals are re$ ected from e.g. tissue interfaces within the body. The achievable resolution and contrast are directly dependent on the choice of weights. Conventionally, a set of pre-de! ned, data-independent weights is used.

The scope of the project is to investigate and re! ne adaptive beam forming methods used in e.g. radar systems and apply these to the ! eld of ultrasound imaging. These adaptive methods utilize the actual data to ! nd a set of optimized data-dependent weights. In this way, each point of the image is weighted di" erently. The adapted weights yield increased resolution and contrast of the ultrasound images.

The adaptive beam forming methods can increase the resolution and contrast of ultrasound images. The increased image quality may improve future diagnostic purposes.

Completed: 2009 Iben Kraglund Holfort

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 CENTRE FOR ELECTRIC TECHNOLOGY Head of Centre: Professor Jacob Østergaard Head of Electric Energy Systems Group: Professor Jacob Østergaard Head of Electric Components Group: Associate Professor Joachim Holbøll Head of Automation and Control Group: Associate Professor Ole Ravn

ur centre focuses on the challenges of modern electric power systems. We contribute to solve the technological Ochallenges related to a transformation of the electric power system into a sustainable, economic and reliable system with an increased share of renewable energy sources. # rough successful collaboration with the Danish energy industry and supported by DTU and EUDP-funds, we have started the implementation of phase I of PowerLabDK, an experimental platform. PowerLabDK is to be an international unique platform for research, development and demonstration of intelligent energy technologies supporting the path towards green growth to the bene! t of the Danish society and industry.

In 2009 we successfully concluded several research projects, including the EU “More Microgrids” project dealing with islanding experiments in the Bornholm distribution grid. # e theoretical development of technology for demand as frequency controlled reserve was completed and a new development and demonstration project has been started. # e EDISON consortium project - Electric Vehicles in a Distributed and Integrated Market using Sustainable Energy and Open Network – was launched in 2009 with our centre as one of the main scienti! c partners in the project. We have hosted and arranged several events, including the 5th Nordic Wind Energy Conference, summer school in phasor measurement units under the EES-UETP (Electric Energy System - University Enterprise Training Partnership), summer university in Wind Energy and several PowerEvents with the energy industry.

PhD Projects

Agent based control of power systems with decentralized production

Denmark’s electric power system exhibits some unique characteristics. An increasing part of the electricity is produced by distributed generators (DGs). Most of these DGs are connected to the network at distribution level. This situation has created an incentive in the electric power industry to utilize modern information and communication technologies (ICT) for improving the system automation and control.

The objective of the project is to investigate the use of intelligent agent technology in connection with the implementation of control and automation strategies for the dynamic segmentation of electric power networks. Power system requirements to dynamic control structures will be identi! ed. Furthermore, the project will investigate how agent technology can be used in these cases to implement $ exible control strategies.

A careful use of intelligent agents and autonomous systems is crucial for the realization of the future sustainable, $ exible and green energy system – the smart grid.

To be completed: 2010 Arshad Saleem

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Electric vehicles in the electric power system with hign penetration of wind power - charge/discharge infrastructure

The actual interest on electric vehicles (EVs) is due to a number of reasons: EVs can provide a unique opportunity to reduce CO2 emissions. At the same time, EVs can play a major role of energy storage solution which will facilitate the increasing penetration of renewable energies, such as wind power. However, a widespread use of EVs poses new technical challenges concerning their charge/discharge infrastructure.

The objective of the project is to design, develop and test a solution for charging/discharging EVs, with the purpose of smoothing out the e" ect of wind power $ uctuations in the power system. The focus will be on the implementation of an e# cient charging architecture for EVs. Furthermore the project will access and develop a vehicle-to-grid concept which can be used for grid power balancing purposes.

An intelligent design of charge/discharge infrastructure is crucial for a spread utilization of electric vehicles, and can improve the overall e# ciency of the grid, while reducing CO2.

Francesco Marra To be completed: 2012

Coordinated frequency control of wind turbines in power systems with high wind power penetration

Conventional power plants are responsible for controlling the frequency of the voltage in the electricity network. Actual wind power does not contribute to this control. The increase in wind power makes the grid frequency control more di# cult. New control solutions for integrating an increased share of wind power need to be developed, dealing speci! cally with the frequency stability problem of high wind power penetration or islanding situations.

The project will develop new control algorithms for the active power control of wind turbines. The frequency problem can be handled by real-time balancing of the wind power production, conventional power production and, eventually, demand consumption. The project is carried out at DTU and Vestas Wind Systems A/S. A full-scale implementation at one or several wind turbines on the island Bornholm will provide a realistic validation.

This project will provide technical solutions and knowledge regarding the design and functionality of the power control of wind turbines for future power systems.

Germán Claudio Tarnowski To be completed: 2010

Development of PMU-based early warning system for electric power systems

The formation of the power system towards increasing the utilization of renewable energy sources combined with a generally more stressed transmission system necessitates research within the ! eld of on-line assessment of the power system stability.

With the development of Phasors Measurements Units (PMUs), it became possible to obtain synchronized wide area “snapshots” of the system’s operating condition which provided a unique opportunity to develop methods for power system monitoring, protection and control. The objective is to develop a method utilizing the bene! ts of wide area PMU measurements to provide an early warning, should instability in the electric power systems occur.

To avoid a widespread system blackout, the early warning method may increase the time window, which the system operators have, to take appropriate countermeasures.

To be completed: 2010

Hjörtur Johannsson

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Overvoltages and protection in o! shore wind power grids

The failure rate of components in o" shore wind power plants is unpredictable. Consequently, there is a need to produce guidelines regarding the modeling of electrical equipment and methods to assess the transient and temporary overvoltages correctly, known to appear in the collection grid of large o" shore wind farms.

A core subject will be the analysis of available measurements in o" shore wind farms with the aim to create digital models of the main electrical components in the collection grid. Once the simulation results and measurements (model validation) are in agreement, transient and temporary overvoltage studies will be carried out to estimate the potential risks correctly.

Based on these models and studies, protection schemes and systems can be evaluated to create the best technical solution to ensure a more reliable wind power plant.

To be completed: 2011

Iván Arana Aristi

Control architecture for future power systems

A major challenge for our society is the transition from fossil fuel based energy systems to a system based mostly on sustainable energy sources. In a large interdisciplinary e" ort the CEESA project aims at developing feasible scenarios for a 100% renewable energy system for Denmark in 2050. Renewable energy sources are bound to increase the complexity of electric power systems, which are amongst the largest and most complex systems man has created.

The goal of this project is to provide an integrative modeling approach to representing and evaluating alternative control architectures. Further, we aim at contributing to improved energy system scenario-modeling. The approach is based on a formal modeling language developed at DTU, which is directly compatible with reasoning techniques of arti! cial intelligence, and can be used to formalize conditions and requirements. A clear formalization of system and component functions makes the systems complexity accessible to IT-based con- trol, which may enable more dependable control structures.

To be completed: 2011 Kai Heussen

Transient conditions in power generating systems

In 2003, Eastern Denmark and Southern Sweden experienced a voltage collapse causing a blackout which for some consumers in Denmark lasted about six hours. The costs of this event were high, both for the society and the numerous power stations experiencing damage. The issue is how you can avoid an incident of this nature happening again. This PhD project is one of the projects initiated by this event.

The project comprises detection, categorization and analysis of transients occurring in the Danish grid, including evaluation of the changing types of electric power generation, investigation of actual faults in electric power generating plants or power transmission systems, and normally occurring operational events. Finally, risk analyses of some chosen units based on the identi! ed impacts are performed.

The project explores the impacts which power generating plants may be exposed to during transient in$ uences to improve the understanding of the impact and to avoid damage.

Completed: June 2009 Morten Erlandsson Lunow

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Superconducting wind turbine generators

The energy need of the world’s growing population is forcing restrictive measures as to the e# ciency of today’s energy production and ‘green’ energy. More e# cient electrical machines in the wind industry will lead to better exploitation of green energy and a decrease in CO2 emission. Another important attribute in the wind industry is the power density, especially in the o" shore sector, where the size of the turbine is expected to approach 10 MW.

The objective is to investigate the bene! ts of superconductors (SC) in electrical machines focusing on wind generators. Carrying DC current at cryogenic temperatures without energy loss, SC coils can generate magnetic ! elds up to 10 T. Consequently, SC machines have higher power density and are smaller and lighter. Increase in e# ciency, better stability, smoother operation and a better dynamic performance are other expected attributes.

Light weight and more e# cient, direct driven wind generators in the power range of 10 MW are necessary to allow the advancement of the o" shore wind industry. SC machines can deliver that.

To be completed: 2011 Nenad Mijatovi

Virtual power plants for distributed energy resources including electric vehicles – ICT architecture and communication

The purpose of a Virtual Power Plant (VPP) is to actively integrating distributed energy resources (DERs) in the power system and market by introducing an aggregated system where multiply controllable loads/DERs are partly or fully controlled by a single coordinating entity.

The PhD project focuses on the ICT standards and protocols that will facilitate communication between power sys- tem components, VPP aggregators and end-users. Relevant parameters such as security, reliability, interoperability and performance must be evaluated. The result should be a set of technology recommendations and the development of a demonstration platform.

The PhD study is tightly coupled to the ongoing EDISON and VPP projects in which IBM and CET participates and to which the student should make contributions throughout the study.

To be completed: 2012 Peter Bach Andersen

Exploiting ancillary services from distributed generation by means of standardized communication

Distributed energy resources have been and are still widely implemented in the electric power system. To maintain the secure and $ exible operation of the system, the demand arises for utilizing not only the primary energy production, but also ancillary services from the distributed resources. This demand can only be met if a coherent information and communication system tightly integrates the distributed resources with the rest of the system.

The objective is to contribute to the development of an internationally standardized information and communication system for distributed energy resources and to investigate how new markets can facilitate the delivery of ancillary services from distributed resources. The ancillary services may include reactive power, frequency control and reserve capabilities.

With a good information integration of distributed resources, they change from being a challenge to the system to playing a very important role in the intelligent power system of tomorrow.

Preben Nyeng To be completed: 2010

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Electrical structure of future o! shore wind farms with a HVDC transmission connection

Wind farms are moving o" shore due to good wind conditions and in order to keep them out of sight. The distance between the wind farm and the grid connection point might be large, depending on the size of the farm, and AC transmission with submarine cables is no longer suitable. DC transmission based on voltage source converters (VSC) - HVDC is intriguing under these circumstances.

There may be various electrical con! gurations of wind farms and connection from the collection grid to the transmission grid. It is not totally clear which topology would be the best suited. Should the preferred transmission type be HVDC? Transmission of wind power over long distances becomes possible and with VSC converters, wind farms can be set to control a number of grid variables.

This project will evaluate di" erent transmission and wind farm collection grid options in relation to the control of wind farms under various conditions.

Ranjan Sharma To be completed: 2011

Real-time simulation of active distribution networks with a high penetration of renewable energy

The electrical power supply systems of the future will be characterised by a high proportion of renewable energy sources, by decentralised, externally determined generation and increasingly by a strongly developed electricity busi- ness. This particular integration of distributed renewable generation sources into the electricity grid poses a number of challenges for the industry. Utilities will be faced with issues of enabling high penetration of wind power into both existing and future distribution networks.

The objective of the project is to investigate the in$ uence of renewable energies and distributed power production on the operation of active distribution networks based on the advanced real-time simulation platform. The challenge of making accurate simulation of small coupled systems will be addressed. Furthermore, a method to realize power hardware-in-the-loop (PHIL) simulations is investigated.

Based on these real-time models and studies, power system operation problems are identi! ed faster, operating schemes and technical solutions are designed and tested. Seung Tae Cha To be completed: 2012

Generic virtual power plant for optimized micro CHP operation and integration

Micro-combined heat and power (micro CHP), based on fuel cells or internal combustion engines, is a new technology under rapid development. Being a representative of distributed energy resources (DER), millions of these units are foreseen in the energy system to bring the society towards more sustainable energy. This requires an innovative control concept to handle the complexities and challenges.

The objective is to develop and validate the novel control architecture named generic virtual power plant (GVPP). By organizing an internal electricity market, DER units based on di" erent technologies are aggregated. Seamless linkage between the internal and the global electricity market is provided by the GVPP also. Optimized operation and integra- tion of the DER units are thus achieved.

GVPP provides solutions to ensure a future reliable electric power system and a well-functioning electricity market targeted at the satisfaction of every DER owner.

To be completed: 2010 Shi You

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Composite based overhead line systems

The public resistance to new overhead line systems in Europe and other parts of the world has been considerable for many years. More environmentally friendly and less visible overhead line systems are seen as steps towards improving the public opinion. In particular, as these are often technically preferable choices instead of cables. Composite material based overhead line systems show a promising potential as being such a solution.

In the project several aspects of the electrical line components’ properties based on composite materials are investigated. These are voltage and current related dimensions, insulation requirements and coordination in respect of electrical loading and climatic in$ uences, earthing and clearance. A design for future light - but reliable - overhead line systems based on extensive use of composites will be worked out.

Composite based overhead line systems have a large potential for application in the power transmission system where focus on environmental and visual in$ uence is essential.

To be completed: 2010 Thomas Kjærsgaard Sørensen

Impact of wind power on power system small signal stability and wind turbine small signal stability models

In recent years power systems around the world have experienced and are experiencing an immense growth of in- stalled capacity of wind power. And as such, wind power is playing an ever larger role in the balancing and the stability of electrical power systems. From a system perspective this increases the requirements to the wind turbines, as they are expected to support stable operation of the power system.

In this PhD-project implication of wind power on dynamic stability of power systems is investigated. The project seeks to establish how the wind farms should be e# ciently modeled for the analysis, which e" ects the wind farms have on the dynamic stability, and whether the wind farms can contribute positively to the stability.

Insight into the interaction of wind power and dynamic stability will enable further expansion with wind power in power systems su" ering with dynamic stability issues.

To be completed: 2011 Thyge Knüppel

Control architecture for intentional islanding operation in future distribution network with high penetration of distributed generation

Currently, more distributed generations (DG), such as wind turbines and combined heat and power plants, are penetrating into the electric distribution system. How to control them to maintain the security of the power supply, especially during emergency situations, is of great interest since most of the present control strategies do not consider their high participation. Within this scope, a possible solution may be intentional islanding operation.

This project will develop a control architecture for the electric distribution system during operational disturbances and faults via intentional islanding operation. As part of the NextGen project, this project focuses on system modeling and simulation regarding the control architecture and recommends the development of a communication and information exchange system based on IEC 61850.

The islanding control architecture can assist the power system operator to maintain the security of supply and develop a more $ exible smart grid with high penetration of DGs.

Yu Chen To be completed: 2010

23

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 CENTRE FOR PLAYWARE Head of group: Professor Henrik Hautop Lund

n our cross-disciplinary research centre, we focus on how playful aspects of robotics and interactive technology may provide Imotivation for any citizen to perform di& erent kinds of interaction. We combine modern arti! cial intelligence, modular robotics and entertainment to provide novel opportunities in play, rehabilitation, sport, music, teaching, third World development etc.

We consolidate and expand in a new, self-contained ! eld of research and industrial enterprise, which combines humanistic and technological research under the term playware, de! ned as: “intelligent hardware and so$ ware that aims at producing play and playful experiences among users of all ages”. Our ! eld comprises not only existing digital products for promoting play, entertainment and learning but most of all new ones arising from more recent technologies such as robotics, ambient intelligence, pervasive and ubiquitous computing, and mobile technology, that allow for the creation of intelligent physical objects.

We explore the possibilities a& orded by ambient technology and modern arti! cial intelligence for developing new play environments, toys and learning objects in close collaboration with major Danish and international companies within play and play equipment (LEGO, KOMPAN, etc.). Also, we utilize research to develop novel welfare technology, e.g. for elderly home care and rehabilitation, which provide high motivation for the users to interact and perform desired actions.

Our centre is an interdisciplinary research centre with researchers from humanities, arts, and engineering.

PhD Projects

Pervasive games - design of digital games distributed in physical space

Humanistic Informatics, specialization in digital games, digital production and human-system interaction are factors of great interest within our ! eld of research. My project is focused on pervasive games and focus of my research will be put in understanding what kind of play pervasive games makes possible. Through experiments and observations I explore how gaming in physical space can alter the experience of the space.

The project focuses on design principals for pervasive games.

Stine Ejsing is enrolled at DPU (The Danish School of Education). She is studying and working at the Centre for Playware (located at DTU) as part of a collaboration between DTU and DPU.

To be completed: 2010

Stine Ejsing-Duun

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 “Play” - a socio analytical diagnosis of contemporary society

The background of this project is to be found in intellectual history. On the basis of a number of empirical studies of children’s everyday life the project is outlining - through a socio analytical diagnosis of contemporary society - “play” as a sensory activity for production of meaning.

Characteristical for the “play” is that it is a voluntary activity, a goal in itself and takes place as an event framed outside from other everyday life activities. Unlike other activities, which produce meaning, playing is at one side dependent on repetition, but at the same time it is a necessity that play can continue in addition of new “play-value” all the time. Otherwise, the “play” has to stop. The constant addition of new “play-value” is crucial for the design of the “play”.

Helle Skovbjerg Karo" is enrolled at DPU (The Danish School of Education). She is studying and working at the Centre for Playware (located at DTU) as part of a collaboration between DTU and DPU.

To be completed: 2010

Helle Skovbjerg Karo!

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 ELECTROMAGNETIC SYSTEMS Head of group: Professor Olav Breinbjerg

ur group is responsible for research-based teaching in the areas of electromagnetic ! eld theory, antenna technology, Ometamaterials, microwave technology and terahertz technology.

Our research is theoretical, numerical, and experimental ranging from fundamental engineering science to applications at component, circuit, and system level in communication, imaging and sensing.

We are engaged in numerous external national and international co operations with academia and industry. # e group operates several advanced laboratories; e.g. the DTU-ESA Spherical Near-Field Antenna Test Facility which constitutes an external reference laboratory in high-accuracy antenna measurements for the European Space Agency. # e research areas for 2009 are re" ected in the Ph.D. projects described below.

PhD Projects

Highly compact radar circuits utilizing LTCC technology

The project aims at developing LTCC technology suitable for integration of existing Doppler radar systems, such as those of Weibel’s Scienti! c radar systems. The goal is to achieve a drastic reduction in size of the existing radar circuits. With increased compactness, the system’s electronics properties will exhibit improved performance in terms of shorter signal paths, less noise, better temperature control, easier mechanical design etc.

More compact radar modules will make it less expensive and easier to build phased array radar systems which, in combination with an overall reduced size of the radar, will enable a range of new applications for Doppler radars. LTCC compatible ferrite materials will also be investigated with the aim to embed non-reciprocal components such as circulators and isolators in a LTCC module.

The objective is to create a Low Temperature Co! red Ceramics (LTCC) front-end module for an X-band Doppler radar.

To be completed: 2010

Thomas Jensen

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Wireless communication for hearing aid systems

The objective is to develop key technologies enabling very small autonomous devices – like e.g. hearing aids – to be incorporated in wireless networks. A key bottleneck as regards the practical realization is the size and e# ciency of the antennas and the supply and consumption of energy of the devices. Speci! c focus will be on antennas, encapsulation and packaging, and wireless transfer of power.

The project comprises three major areas of investigation – ear-to-ear communication, propagation measurements and magneto-dielectric antennas. Wireless coupling between hearing aids will be characterized based on theoretical simulation and practical measurements during the ! rst half of the project. The second part will be concerned with the minimization of antennas using materials that have a high permittivity and permeability.

Most studies of wireless communication concern far-! eld communication, while this project is focused on communication in the reactive region of antennas.

To be completed: 2011 Baqer Nour

Design of integrated circuits approaching terahertz frequencies

For a few years there have been very intense development e" orts worldwide on imaging for security applications. The market for mm/sub-mm wave components and modules will thus probably grow signi! cantly. Furthermore, it is expected that mm/sub-mm wave imaging will increasingly be developed for space and military applications.

The objective is to design and characterize MMIC circuits for the frequencies starting at E-band and up to 600 GHz with improved performance in terms of e# ciency, phase-noise and power. A second objective is to develop analysis techniques to determine the RF performance including phase-noise using modi! ed analysis tools.

The project results will be MMIC components for receiver and transmitter applications in millimeter-wave bands and at least one MMIC operating beyond 300 GHz.

To be completed: 2010

Lei Yan

Microwave Instrument for vital signs detection and monitoring

The ! rst experimental results of using microwave instruments, e.g. radar and radiometers etc. for detection and monitoring of human vital signs like heartbeat and respiratory activity was published in the 1970s. Since then, numerous publications have treated this subject in order to establish the fundamental theory and to test the viability of such a non-contact vital signs instrument.

The human respiratory and heartbeat movements are relatively slow and thus require state-of-the-art phase-noise instrument architectures and components. The purpose of the PhD project is to design, implement and verify a compact, low-power radar-based instrument, using commercially available components in conjunction with MMIC technology to design some of the most critical components.

The applications are many. One example is to use the instrument for monitoring patients at hospitals for increasing patient mobility and ease the use of such instruments for sta" .

To be completed: 2012 Brian Sveistrup Jensen

27

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Development of high power ampli" ers for radar applications

Advanced radar systems have received considerable attention due to the increased demand in remote sensing and imaging applications both for terrestrial and space systems. A key element in this system is the high power ampli! er, which has experienced a renewed interest due to the enormous progress in solid-state technology and devices. An emerging technology particularly promising for high power ampli! er realization is GaN device technology.

The scope of the PhD project lies in the development of design methodologies, nonlinear modeling, manufacturing, packaging and e# cient testing of solid state high power ampli! er modules. A further goal is to develop a high power ampli! er for X-band frequencies with capabilities to replace the vacuum tubes currently used in commercial radar systems.

Advances in high power ampli! er technology will help reducing the system size and cost, and enhancing transmission rates and target detection.

To be completed: 2011 Carlos Cilla Hernández

Microwave and millimeter-wave integrated circuit systems in packaging

When integrated circuits operate in the millimeter-wave range even approaching the terahertz range, the parasitic e" ects due to the packaging and interconnection structures may deteriorate the performance of the systems. The packaging designs for millimeter-wave integrated circuits are very challenging and crucial for achieving the desired performance in relevant applications.

Accurate 3D electromagnetic (EM) simulation techniques are developed to investigate the parasitic e" ects in various packaging and interconnection structures. The EM simulation is innovatively extended to model devices, such as photodetectors. A photodetector package for 100 Gbit/s Ethernet applications is designed with 3dB bandwidth exceeding 100 GHz by using 3D EM simulations.

Successful packaging designs aiming at millimeter-wave applications o" er the possibility of integrating systems with superior performance and limited parasitic e" ects.

Completed: November 2009 Chenhui Jiang

Microwave and millimeter-wave signal power generation

Microwave and mm-wave high-speed communication systems and high-resolution radars require e# cient generation of linear signal power. Distortion in communication channels and radar applications originates largely from high-power ampli! ers (HPAs). Power consumption in a transmitter is highly dependent on the PA’s e# ciency. Besides HPAs, the emerging mm-wave communication systems require low-noise tuneable quadrature oscillators (QVCOs).

One objective is to assess GaN HEMT technology with respect to linear e# cient generation of high signal power. A two-stage HPA MMIC has been developed. The second objective is the mm-wave technology study and development of an InP HBT based E-band HPA. Detailed comparison with a SiGe HBT technology has been performed using an accurately extracted model of a SiGe device. Another circuit developed in InP HBT technology is an mm-wave QVCO.

High breakdown technologies such as GaN HEMT and InP HBT are very suitable for the construction of HPA and oscillator circuits with high e# ciency, power and frequency of operation.

Completed: June 2009 Dzenan Hadziabdic

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Antenna miniaturization in complex environments

Hearing aids already constitute an advanced technology, and wireless communication integrated into hearing aids will open for a range of completely new functionalities. The antenna is an important component in wireless systems, and the demand for compact systems with stringent speci! cations makes antenna size reduction a signi! cant challenge. Antenna miniaturization is one of the key technologies in designing a successful wireless unit.

This project aims at designing ultra miniaturized antenna systems for hearing aids, in which the antennas are geometrically and electrically small. The antennas are to function in very complex environments in$ uencing the performance of the antennas signi! cantly, and this fact should be taken into account. The development of a highly accurate measurement facility is necessary to investigate the performance of small antennas.

The antenna miniaturization technique is of high importance as regards the design of compact wireless networks and devices.

To be completed: 2010 Jiaying Zhang

Accurate modelling of advanced re# ect arrays

Re$ ect arrays combine the best features of re$ ector antennas and array antennas, and is considered as a promising candidate for realizing low-cost high-gain antennas for satellite communications. The design and realization of advanced re$ ect arrays rely heavily on numerical analysis and accurate analysis of re$ ect arrays is presently a challenging problem. In addition, re$ ect arrays tend to have smaller frequency bandwidth compared to conventional re$ ector antennas.

This project is aimed at proposing solutions to the lack of accuracy in present re$ ect array modelling and to develop new algorithms for synthesizing and analyzing re$ ectarrays. The project will set a new standard for the modelling accuracy of re$ ectarrays and consequently make it possible to design such antennas with much better agreement between measurements and simulations.

It is expected that improved modelling tools will enhance the performance and usability of re$ ect arrays, and greatly contribute to solving the bandwidth issue associated with re$ ect arrays.

Min Zhou To be completed: 2012

Antennas and propagation for body-centric wireless communication

Body-Centric Wireless Communication is the enabling element of Wireless Body Area Networks, consisting of two or more body-worn devices. These devices could e.g. be medical sensors for monitoring the health of a patient, or wireless headsets. The challenge is twofold when designing antennas for such devices; The close proximity of human tissue drastically a" ects antenna performance, and the antenna is often con! ned to a small volume.

The project focuses on the implementation of wireless capabilities in hearing aids. These tiny, yet highly advanced devices constitute a challenging platform for wireless communications. The hearing aids should be able to communicate among themselves, and with other devices, either body-worn or o" -body. The applicable radio channels will be characterized, and appropriate antennas designed.

Wireless-enabled hearing aids o" er a range of new features compared to traditional hearing aids.

To be completed: 2012

Søren Helstrup Kvist

29

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 ELECTRONICS GROUP Head of group: Professor Michael A.E. Andersen

n our group we conduct research in power electronics on physics-, component-, and system levels ranging from mega- IWatt to milli-Watt power converters. We also perform research within signal conditioning electronics as well as analogue and mixed-mode IC-design. Currently our research is focused within the areas: Fuel-cell power converters, switch-mode power supplies and technologies, class-D switch-mode audio power ampli! ers, as well as on piezoelectric transformer based power supplies. In each of theses focus areas we have several PhD students collaborating with industrial partners on di& erent applications.

While one PhD student le$ a$ er ! nishing her PhD, this year 4 new PhD students started in the group. Two of these PhD students are working on a newly granted large research project on piezoelectric transformer based switch-mode power supplies for a dielectric elektro active polymer actuator funded by Danish National Advanced Technology Foundation.

# rough numerous papers as well as a patent application we have on several occasions shown how world record high 98% e% ciencies for fuel cell converters can be obtained using partial paralleling of multiple primary power stages while still maintaining lower cost. # is is obtained by only paralleling primary switches and the critical high ac-current loop.

PhD Projects

New technology-driven approaches in the design of preampli" ers for condenser microphones

MEMS condenser microphones are increasingly popular in high volume consumer electronics products due to their lead-free solder re$ ow compatibility, small volume and ease of integration with CMOS circuitry. The easy integration has led to microphones with new functionalities such as digital output requiring an analogue CMOS interface implemented in the modern low voltage and submicron processes used for CMOS digital design.

The objective is to investigate how the physical characteristics of modern CMOS technologies in$ uence the performance of preampli! ers with a capacitive input source. Furthermore, new methods for low-noise ampli! cation of a capacitive microphone signal are investigated.

The new approaches for noise minimization are expected to provide very low-noise, robust, and high performance building blocks for future generations of silicon microphone products.

Completed: June 2009 Jelena C. Haas-Christensen

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Ultra-fast tracking power converters for RF power ampli" ers

Base station applications and TETRA/TEDS networks are used extensively for professional high-reliability communications by the police and other emergency services. The project examines methods of increasing the e# ciency of narrow-band radio transmitters.

The general solution space studied is that of envelope tracking applied to linear class-A/B radio frequency power ampli! ers (RFPAs) in conjunction with Cartesian feedback (CFB) used to linearize the overall transmitter system. The problem of extracting maximum control bandwidth from switch-mode power supplies has been given particular attention.

The project demonstrates a doubling of RFPA e# ciency by adding an optimized but low-cost switch-mode power converter and the application of optimized Cartesian feedback.

To be completed: 2010

Mikkel C.W. Høyerby

Modular power electronic converters with galvanic isolation in the power range 1 to 10kW

The electrical output power from fuel cells is typically a low dc voltage in the range of 30 – 60 V at power levels of 1-10 kW. Switch-mode converters are used to convert output voltage to user levels (230 Vac). The high input current seen by this converter, however, causes converter e# ciency to drop signi! cantly (<90%), thus reducing output power and increasing fuel consumption.

The objective is to ! nd methods to increase converter e# ciency in low-voltage to high-voltage dc-dc converters suitable for fuel cell applications. The goal is to achieve a maximum conversion e# ciency of 98 percent. Furthermore, the project will analyze ways of achieving optimum scalability of power converters in the power range of 1 – 10 kW.

By increasing output power and reducing fuel consumption, high e# ciency power converters will reduce the cost of fuel cell generated electrical power.

To be completed: 2010 Morten Nymand

Improvement of out-of-band behavior in switch mode audio power ampli" ers and power supplies by their modulation topology

The latest generation of ampli! ers and power supplies in the entertainment industry comes with the tendency to disturb the functionality of radio and television receivers by electromagnetic in$ uence. This leads to bad reception of programs and limits the ability for information transmission. Conventional solutions require bulky and expensive electronic and mechanical components to alleviate this problem.

Therefore, we strive towards more intelligent solutions to overcome this drawback by means of putting more intelligence in the less expensive control and modulation part of switch-mode power electronics while conserving the high energy e# ciency of these circuits. We mainly deal with music ampli! ers and their power supplies up to 500 W and have a connection with the automotive entertainment industry.

We will provide better functionality for smaller entertainment electronics by smarter means in power electronic circuits. Three patentable solutions have been established so far.

Arnold Knott To be completed: 2010

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Powering the future data centre

Environmental constraints, increased energy costs and the maintenance costs of the generator and the batteries in extended run time Uninterruptible Power System (UPS), drive the need for new technologies. Fuel cells are an obvious choice to supply the extended run power, and super-capacitors could be an interesting alternative to traditional batteries due to their excellent lifetime and no-maintenance properties.

This project aims at researching, investigating and comparing possible solutions to integrate the fuel cells and supercapacitors with power electronic circuits in the UPS to obtain energy e# cient and cost e" ective solutions for future data centre applications. Furthermore, alternative topologies of the overall data centre are researched to optimize the total e# ciency of the system with multiple sources and consumers.

This project aims at building a high e# cient, high energy density and environment-friendly extended run UPS power system with emphasis on the use of fuel cells and super-capacitors.

To be completed: 2010 Zhe Zhang

Energy optimized photovoltaic module

Existing solar cell systems function by having a single inverter with built-in Maximum Power Point Tracking algorithm. All the solar cells are coupled in series and thereby the current $ owing through the cells will determine where the local cell is operating at its individual I-V curve. Thus only a fraction of the solar cells will operate in Maximum Power Point (MPP) considering the production tolerance and external factors like sunlight and dust.

The objective of the project is to develop a suitable output stage for the photovoltaic system which will facilitate e# cient transfer of generated power to the grid without introducing considerable disturbances to the output of the solar module. The project investigates the suitability of di" erent topologies available and intends to resolve the fundamental problems of the system by choosing the most appropriate topology for the output stage.

The success criteria of the project is an increase in the power output and improvement in the performance of the photovoltaic system with e# cient power conversion and suitable control scheme.

To be completed: 2011 Reshmi C. Variath

Digital DC-AC boost ampli" cation for portable audio

The project combines the step-up functionality with class D ampli! cation in applications running from a low supply voltage. The intention is to o" er a better sound pressure level in applications where electro dynamic transducers are used, typically 8 Ohm, and to open up for new transducer types such as piezo-ceramic speakers requiring a high operating voltage to improve the sound pressure levels.

The objective is to investigate such a concept thoroughly identifying the most suitable implementation for the most promising application area. At one end, mobile phones represent a possible application area, whereas an automotive application is located at another. Digital control methods and pulse referenced control should be considered to deal with the special requirements of the battery driving the power converter.

The perspective is to obtain such a power converter and control system with diagnostics and protection features us- ing innovative techniques to improve sound quality and energy use.

To be completed: 2011 Gert B. Maizonave

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Innovative magnetic-less high power density switch-mode power supplies based on piezoelectric transformers

Piezoelectric transformers (PT) are electrical energy converters based on acoustic coupling, analogous to magnetic transformers based on coupling though mutual inductance. Recent advancements in piezoelectric transformer design have made the technology attractive for research in high power density and low EMI power converters in the range of 10-100W.

E# ciencies of up to 98% at 40W/cm3 have been demonstrated for a ring shaped transformer at the size of a coin and a height of only 4mm. Currently, the technology has only been used for lamp ballast drives and LCD backlighting, but the focus of this project is on PT based magnetic-less power supplies with a DC output voltage, a variable load and galvanic isolation.

This comprises research on power stage topologies, closed loop control, and PT transformer optimization towards AC/DC and DC/DC converters.

Kaspar S. Meyer To be completed: 2011

Flexible power module for fuel cell hybrid power system in a forklift

Fuel Cell Hybrid Vehicles (FCHV) are becoming a popular means of increasing the energy e# ciency and reducing emissions. In fuel cell applications, batteries are employed to reduce the size of the fuel cell, to recover braking energy during regeneration, and to keep the fuel cell in its high e# ciency region. The variable voltage of the fuel cell has to be matched to the battery voltage via a DC/DC converter for charging.

The primary objective of this research project is to investigate more simple and more e# cient topologies of low cost DC/DC medium power converters for a fuel cell fork-lift. It should be possible to redesign the converter architecture for di" erent output voltage and power levels in various applications.

This will lead to a more e# cient conversion of fuel cell power as well as reduced size and less cooling needs.

To be completed: 2011

Gökhan Sen

Planar magnetics for high grade converters

Planar magnetics has been known and used for many years, but is still not a commonly used technology, mainly due to a limited number of commercial suppliers and the lack of dedicated design tools. The increasing demand for high e# cient power converters with high operating frequency, low mass and low pro! le brings a special focus on the magnetic parts of the converter.

The objective of this project is to develop new design techniques and simulation models for the planar magnetics to be used in high grade power converters in the range from 50 W to 2kW. This project should also provide the excellent solutions for achieving high e# ciency, high power density, and low pro! le.

This will provide a trend towards the high power density and low volume transformers used in high grade converters.

To be completed: 2011

Ziwei Ouyang

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 E$ ciency power factor correction (PFC) frontend for class-D ampli" ers

With demands of increasing power densities and reduction of losses for switching power supplies in industrial applications, research on maximizing power e# ciency turns to have signi! cant meaning. Innovation of Power Factor Correction (PFC) technology is an important method to achieve high e# cient and low electromagnetic interference (EMI) power supply.

Since traditional PFCs cannot avoid many natural power losses from their structures, the aim of this project is to achieve a high power and high e# cient PFC frontend for Class-D ampli! er through comparing, researching, and innovating traditional PFC converters. Furthermore, latest circuit topologies and control theories will be studied to realize a cost-e" ective product and reach better performances.

A 3.5kW high e# cient, high energy density and low EMI PFC converter will be built, and the advantages will be shown obviously depending on topology optimization and control innovation.

To be completed: 2012 Qingan Li

Piezoelectric transformer based power supply for DEAP

Dielectric Electro Active Polymer (DEAP) for use in applications such as surgical tools, grippers for material handling and valve actuators, works by charging the actuator to a high voltage (up to 2.5kV). Conventional high voltage power supplies based on magnetic transformers are used for charging, unfortunately the e# ciency of these power supplies are below 70%, limiting the use of the DEAP technology as the supplies are large and bulky.

To extend the range of the DEAP technology, high voltage power supplies based on piezoelectric transformers (PTs) are studied with the aim of increasing e# ciency (>90%) and miniaturizing the overall size. This involves innovation within PT designs to increase the power density for high gain PTs, and new topologies for reducing the amount of components.

The properties of a new PT based SMPS (compact, high e# ciency) make it a perfect match to the DEAP technology and will insure new actuator solutions for medical, automotive, industrial, and consumer industries.

To be completed: 2012 Thomas Andersen

Controller IC-design for piezoelectric transformer based power supply

The Dielectric Electro Active Polymer technology (DEAP) has a wide potential in applications such as surgical tools, grippers and valve actuators etc. But currently no suitable high voltage power supply for the DEAP technology exists, thus limiting its use. The unique properties of the new Piezoelectric Transformer (PT) based power supply (compact, low weight, high e# ciency, non magnetic and superior EMI/EMC performance) make it a perfect match to the DEAP technology.

My research will be conducted into a high voltage (HV) Switch-Mode Power Supply (SMPS) based on Piezoelectric Transformer (PT) that enables the use of the Dielectric Electro Active Polymer (DEAP) technology as an actuator. In addition high priority is given to the development of a simple, e" ective, and $ exible control circuit for the PT based SMPS, which incorporates bidirectional power $ ow and is integrated in a dedicated control integrated circuit (IC).

The PT has a huge potential compared to conventional magnetic SMPS concerning mass production price, as well as the earlier mentioned advantages, but it is still a fairly novel technology.

Martin Schøler Rødgaard To be completed: 2012

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Design of digital audio class-D output-stage with feedback with emphasis on hearing-aid application

It is a known fact that the dimensions of the electronic devices will scale down and the number of transistors on one microchip will double every two years. This goes hand-in-hand with digitalization. The back end of the audio system - DAC and power ampli! er – is a subject of this trend as well. The ! rst classes of output stages were A, B and C. With the coming of digitalization class D was introduced merged with PWM and SD modulation DACs.

Project targets low-voltage low-power IC design of the back end of an audio signal processing path – a DAC and an output stage. These blocks highly in$ uence the current consumption of the whole system. The consumption should be kept low to prolong the lifetime and to reduce the battery size of portable electronic devices. This project aims to implement the circuit with digital blocks, reducing the analog circuitry needed and to save power.

Considerations on modulator, output stage, and feedback design with respect to low-power low-voltage – resulting in FPGA implementation and two ASIC tape-outs.

Peter Pracny To be completed: 2012

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 HEARING SYSTEMS Head of group: Professor Torsten Dau

ur group “Hearing Systems, Speech and Communication” investigates various aspects of human auditory signal processing Oand perception, speech recognition and processing, physiological acoustics and audiology, hearing-diagnostic technology, compensation techniques in digital hearing aids, and virtual auditory environments. A major part of our research and teaching activities is conducted within the Centre for Applied Hearing (CAHR).

We recently achieved to establish new objective estimates of group delays in human inner-ear processing based on acoustically- evoked potentials and otoacoustic emissions (“cochlear echoes”). We developed new Danish “Hearing in Noise” tests for reliable assessment of speech intelligibility in normal-hearing and hearing-impaired listeners. Furthermore, we established a loudspeaker-based virtual auditory environment which allows the simulation of complex natural sound source scenarios and thereby bridges the gap between laboratory-based listening tests and real-life experiences.

Our research has been supported mainly by grants from the Danish hearing aid industry, the Danish research council, private foundations, the graduate school “Sence organs, nerve systems, behavior and communication” and the EU (HearCom project). Many of our projects have been in collaboration with the Danish hearing aid industry and/or our colleagues from other Universities mainly in Germany, England, the Netherlands and USA.

PhD Projects

Peripheral auditory processing and speech reception in impaired hearing

People with impaired hearing often encounter great di# culty in understanding speech, particularly with background noise. The bene! t from hearing aids varies among listeners. It has been hypothesized that part of the di# culty arises from changes in the perception of sounds well above hearing threshold such as reduced frequency selectivity and de! cits in the processing of carrier-temporal-! ne-structure at the output of the inner-ear ! lters.

The scope of this project was to investigate relations between frequency selectivity, temporal-! ne-structure processing, and speech reception in listeners with impaired hearing. For this purpose, behavioral listening experiments as well as objective measurements of auditory evoked potentials were used.

The gained insights into auditory processing in listeners with impaired hearing may have implications for models of impaired auditory processing as well as compensation strategies in modern hearing instruments.

Completed: June 2009

Olaf Strelcyk

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Characterizing binaural processing of amplitude-modulated sounds

Binaural hearing provides bene! ts over monaural hearing in the detection of auditory signals in complex acoustic environments and can reduce negative e" ects of reverberation on speech intelligibility. Current models of speech intelligibility in rooms, based on the transmission of amplitude modulations in speech signals, do not consider the bene! ts of binaural listening and may underestimate speech intelligibility as a result.

Psychoacoustic experiments were performed to measure human abilities in the detection of sound amplitude $ uctuations in anechoic and reverberant spaces, and to measure interactions between spatial hearing and amplitude modulation processing. These data and data from a consonant identi! cation in reverberation experiments will be used to improve binaural models for signal detection and speech intelligibility.

This research will provide insight into human performance in complex listening environments, which will be used to improve models of hearing and assistive listening devices.

Completed: August 2009 Eric Thompson

Spectro-temporal analysis of complex sounds in the human auditory system

Many natural sounds including speech contain amplitude modulations. It is commonly assumed that a comparison of amplitude modulations across frequency by the auditory system plays an important role for the extraction of signals embedded in noisy backgrounds.

The objective of the project was to quantitatively simulate the processing of amplitude modulated sounds in the auditory system. In particular, we tested di" erent signal processing mechanisms for signal enhancement in noisy backgrounds that utilize the coherence of signal information across frequency.

The modeling results from this project will be useful for optimizing the signal enhancement processing strategies in hearing instrumentation such as digital hearing aids.

Completed: September 2009

Tobias Piechowiak

Assessment of speech intelligibility in background noise and reverberation

Reliable methods for assessing speech intelligibility are essential within hearing research, audiology, and related areas. Such methods can be used for obtaining a better understanding of how speech intelligibility is a" ected by various environmental factors or by di" erent types of hearing impairment. Speech intelligibility tests are also essential for the development and ! tting of hearing aids.

In this project, two sentence-based tests for speech intelligibility in Danish were developed; (i) the Conversational Language Understanding Evaluation (CLUE) and (ii) a modi! ed version, which complies with an international standard intelligibility test. The validation of both tests showed that they produce reliable speech intelligibility assessments. The project also included an investigation of the in$ uence of reverberation on speech intelligibility.

The two developed sentence tests are expected to be useful for assessing speech intelligibility with Danish normal- hearing and hearing impaired listeners.

Completed: December 2009 Jens Bo Nielsen

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Hearing aid ampli" cation at low input levels

People with a hearing loss often have a loss of audibility of soft sounds, such as distant voices and birds. This lack of audibility can be alleviated by means of a hearing aid with compression. Previous research from other research groups has produced con$ icting results about how this compression should be ! tted to the individual hearing loss for maximum bene! t of the hearing aid user.

This project considered the hearing aid wearer preference for the hearing aid compression threshold and implicitly the gain at low input levels. Results have been collected using both laboratory listening experiments and ! eld experiments. Results indicate that the preference for hearing aid compression threshold depends on the speed at which the compressor operates, as well as the listening environment and the hearing aid experience of the user.

Improving the hearing aid ampli! cation for low input levels enhances the audibility for speech and environmental sounds, and it also improves the sound quality.

Completed: December 2009 Helen Connor

Modelling auditory processing and speech perception in hearing-impaired listeners

Models of auditory processing and speech perception can help us to understand our auditory system. The consequences of di" erent types of hearing losses for speech perception are not fully understood and there are enormous individual di" erences in performance across listeners, particularly when background noise is present.

The objective of this study is to develop an auditory processing model in order to simulate perceptual consequences of hearing impairment. First a model was designed to predict masking and discrimination data. Then this model was used to derive internal (auditory) representations of speech signals which were used to predict the performance in a consonant identi! cation task in individual hearing-impaired listeners.

In hearing-aid development, the processing of the algorithms has been evaluated in time-consuming subjective listening tests. On the basis of this project, an auditory-model based system could be developed which objectively evaluates the e" ects of hearing-aid signal processing.

Morten Løve Jepsen To be completed: 2010

Implementation and evaluation of a loudspeaker-based room auralization system

Humans are able to communicate in reverberant environments in the presence of disturbing talkers and noise. This ability is investigated in order to design and optimize modern speech and audio technologies, such as hearing aids, cochlear implants, perceptual audio-coders, or automatic speech recognition systems. These investigations require the reproduction of highly realistic acoustic scenarios.

This project aims at implementing and evaluating a loudspeaker-based room auralization system that generates a highly realistic environment suitable for investigating human auditory perception. This system combines acoustic room models with loudspeaker-based auralization techniques. Di" erent multi-channel playback algorithms are implemented and their performance in various psychoacoustic experiments is assessed.

This platform will be useful for studying auditory processing and perception in normal-hearing and hearing-impaired listeners as well as testing hearing-aids in fully controlled and realistic environments.

To be completed: 2010 Sylvain Favrot

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Characterising temporal nonlinear processes in the human inner ear using otoacoustic emissions

Otoacoustic emissions (OAEs) are faint echoes that arise in the inner ear as by-products of the hearing process and can be recorded from the human ear canal. They contain information about the functioning of the nonlinear gain mechanisms present in the hearing process, and are vital for the sharp tuning of the human auditory ! lters.

Temporal features of the inner ear gain mechanisms were investigated by the use of click-evoked otoacoustic emissions (CEOAEs). The experimental results were compared to simulations that were made with a nonlinear adaptive transmission-line model of the inner ear. It was found that temporal changes (0 - 10 ms) in the level of the CEOAE were probably due to temporal overlap of inner-ear impulse responses within this time frame.

Temporal changes in nonlinear gain mechanisms may have consequences for the onset detection of sound stimuli and provide an application for the design of compression characteristics in hearing aids.

To be completed: 2010 Sarah Verhulst

Processing of spatial sounds in the impaired auditory system

A common complaint from people with hearing impairment is di# culty with speech communication, particularly when more than one person is talking at the same time or when background noise is present. The problem often persists even if hearing aids are used. In these complex conditions, normal-hearing listeners take advantage of early re$ ections which increase the speech level when they are integrated with the direct sound.

The bene! t from early re$ ections for monaural and binaural speech intelligibility was measured for normal-hearing and hearing-impaired listeners in a virtual auditory environment. For both groups of listeners, speech intelligibility improved with increased early re$ ection energy. Hearing aids should therefore not only amplify the direct sound, but also integrate spatial information from early re$ ections.

With a better understanding of the underlying mechanisms involved in early re$ ection processing we will be able to suggest advanced hearing-aid processing and ! tting strategies.

To be completed: 2011 Iris Arweiler

Neural coding and perception of pitch in the normal and impaired human auditory system

Pitch is an essential attribute of hearing, which allows us to perceive melodies and chords in music, but also contributes to speech intelligibility and sound source segregation. Whether our auditory system uses neural mechanisms based on temporal information, spectral information, or both, for pitch extraction, remains a central debate in pitch perception research. This project aims to address this fundamental question.

In order to distinguish between possible theories, the project relates pitch perception outcomes to measures of basic auditory functions. Psychophysical experiments are performed in normal-hearing and hearing-impaired listeners, using stimuli with speci! c spectrotemporal properties. Such an approach may reveal how and at which level of the auditory system pitch is represented, and tell us which modeling approach to favor.

If auditory prostheses can transmit the pitch of sounds to hearing-impaired patients in a better way, this will improve their ability to segregate speech sources and enjoy music.

Sébastien Santurette To be completed: 2011

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Investigation of release from masking in normal-hearing and hearing- impaired listeners

People with normal hearing typically show a signi! cant increase in speech recognition when a stationary background noise is replaced by a $ uctuating noise. In contrast, people with impaired hearing often show only very little bene! t from gaps in noise. It has been hypothesized that certain auditory functions are speci! cally linked to the ability to listen-in-the-gaps of a $ uctuating noise and that these functions are degraded in hearing-impaired listeners.

This project investigates which auditory processing de! cits are responsible for the reduced release from masking in hearing-impaired listeners. A model of auditory signal processing is used to investigate how di" erent auditory functions, such as loss of sensitivity and reduced spectral and temporal resolution, a" ect the ability to understand speech in $ uctuating noise.

Identifying the de! cits in the impaired auditory system responsible for reduced speech recognition in background noise will help to improve compensation strategies in hearing-aid signal processing algorithms.

Claus Christiansen To be completed: 2012

Modelling human auditory evoked brain responses to complex sounds

When various auditory stimuli are presented to human subjects, it is possible to record auditory evoked potentials (AEPs) on the surface of the scalp. AEPs can be used as an objective tool to assess hearing de! ciency, for example in new-born screening. AEP generation mechanisms are relatively well understood for basic stimuli such as clicks and tones. However, it is poorly understood how more complex stimuli like speech are represented in AEPs.

The aim of the project is to develop a computational model for AEP generation, based on state-of-the-art knowledge of neural signal processing in the peripheral auditory system. The idea is to quantitatively predict a large set of existing literature data obtained with basic stimuli and to test the ability of the same model to account for speech evoked responses.

The prediction of AEP patterns will help understand how complex sounds like speech are represented neutrally at several stages along the human auditory pathway. The study will also provide a basis for investigating e" ects of hearing impairment on AEPs, which is important for clinical diagnostics.

Filip Munch Rønne To be completed: 2012

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 41

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Awards, honours and appointments

Professor Liselotte Højgaard Liselotte Højgaard, Senior Hospital Physician, Head of Clinic and Doctor of Medical Science (DMSc) was appointed honorary professor within Medical imaging systems in January 2009. An inaugural lecture ”Advanced medical imaging for patients, research and education” was held in May, attracting a large audience. Liselotte Højgaard is one of the main architects of the successful BSc and MSc educations within “Medicine & Technology”, established in 2002 as a multidisciplinary course between DTU and the Copenhagen University. # e 5-year Bachelor/Master program attracts 60+ new students each year and combines courses in basic medical science with courses in applied sciences, classical engineering and core courses in biomedical engineering.

PhD student Klaus Scheldrup Andersen # e prestigious “R.W.B. Stephens Prize” was given to PhD student Klaus Scheldrup Andersen at the International Congress on Ultrasonics 2009 in Chile. # is prize is in recognition of Klaus’ outstanding work within ultrasound and the excellent presentation of his ! ndings within this ! eld. Professor Liselotte Højgaard

Vitaliy Zhurbenko, post-doc. Vitaliy Zhurbenko of our Electromagnetic Systems group was awarded a grant from the H.C.Ørsted Foundation for purchase of equipment for early detection of breast cancer

# e funding will be used to extend the operating frequency band of the Microwave Camera for Breast Cancer Detection in order to achieve a better spatial resolution. # e project aims to develop a novel high sensitive hardware and prepare the camera for clinical trials. # is novel modality can replace or be used along with Ionizing Radiation technologies like X-Ray imaging and improve detection and characterization of breast tumours.

BEng student Jesper Schou BEng student Jesper Schou was awarded the “E-kandidatprisen” for his ! nal project which was carried out in collaboration with the Danish company GN Resound. Jesper’s work deals with the design of an anti-aliasing low-pass ! lter for hearing aids considering the need for low power consumption.

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 MSc student Tobias Gybel Hovgaard # e Oticon Foundation awarded DKK 100.000 to MSc student Tobias Gybel Hovgaard to be used for his ! nal thesis with Danfoss: “Fault tolerant regulation in order to detect and diagnose faults in sensors connected for automatic control of modern cooling systems”.

Professor Mogens Blanke, PhD student Roberto Galeazzi and Associate Professor Niels Kjølstad Poulsen (DTU Informatics) At the IFAC MCMC’2009 Symposium in Sao Paulo, the three DTU researchers received the academic distinction ”Best Regular Paper” for their contribution to “parametric rolling”.

MSc student Kristjan Pall Petursson & PhD student Hjörtur Jóhannsson Grants from the Mogens Balslev Foundation were awarded to MSc student Kristjan Pall Petursson and PhD student Hjörtur Jóhannsson. DTU Rector Lars Pallesen presented the grants to the two recipients in September 2009; grants which are given speci! cally to purposes within education and research in Danish engineering enterprises.

Students Martin Erikshøj & Charlotte Viemose Larsen Two biomedical engineering students Martin Erikshøj and Charlotte Viemose Larsen received prizes at the 27th national congress of the Danish Society for Biomedical Engineering. Subject of the students’ presentation at the congress was: “Hemolysis by Laser Induced Ultrasound”, a method which may be of help within diagnosis of malaria.

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Public outreach

MSc in Engineering Acoustics # e MSc education in Engineering Acoustics was accredited and approved by the Danish Accreditation Institution ACE. More than 40 students are enrolled in this master programme. # is accreditation ensures that the programme meets standards for relevance and quality.

Inauguration Centre for Playware Helge Sander, Minister for Science, Technology and Innovation participated in the festivities in connection with the opening of Centre for Playware. # is interdisciplinary centre is the result of pioneering collaboration between DTU Electrical Engineering and DPU, Danish School of Education at Aarhus University and conducts research on robotics, play culture and arti! cial intelligence. Centre for Playware is headed by professor Henrik Hautop Lund.

Minister for Research, Technology and Development Helge Sander tests one of our latest Playware technologies.

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 World largest pilot project with intelligent electric vehicles: Edison Purpose of this 3-yar project is to develop the technical solutions and infrastructure that will enable the use of electric cars on a large scale. # e Danish Energy Association is managing the project consortium and members of said consortium include IBM, Siemens, DONG Energy, EURISCO and ØSTKRAFT in collaboration with 3 DTU departments: DTU Electrical Engineering, DTU Transport and Risø DTU. # e start-up of the project was marked with a visit by Ms. Connie Hedegaard, Minister for Climate and Energy.

PowerEvent: Test drive of Mitsubishi’s electric car In June DTU Electrical Engineering and Mitsubishi invited the public to try the Electric car iMiEV. # is event is part of a series of so called PowerEvents Associate Professor Sergey Pivnenko and colleagues in action in the DTU-ESA Spherical Near-Field Antenna Test Facility. PhD course on antenna measurements For the second time the Electromagnetic Systems group hosted Earth Explorer satellite an international PhD course ”Advanced Spherical Near-Field # e European Space Agency ESA successfully launched a new Antenna Measurement Techniques”. # e course is organized Earth Explorer satellite called SMOS in November 2009 from under the auspices of the European School of Antennas with12 the Plesetsk Cosmodrome in Russia. participants from 11 di& erent countries. Our Electromagnetic Systems Group has been heavily involved in the SMOS satellite mission SMOS is short for Soil Moisture and Ocean Salinity. # e PhD summer school objective of the mission is to carry out global measurements ”Switch-mode audio power ampli! ers” was the subject of a of these parameters. In this way a better understanding of the PhD summer school held by our Electronics Group in August Earth’s water cycle leading to improved weather and climate 2009 assembling 24 participants from seven universities, six change forecasts. industrial companies and a wide range of nationalities. # e Our Spherical Near-Field Antenna Test Facility has for the participants were presented with the latest research within last four years enabled researchers to develop, implement and ”Switch-mode audio power ampli! ers”. test new hardware and so$ ware to achieve unprecedented accuracy.

RoboMusic at the Roskilde Festival Our Centre for Playware has developed a completely new technology in the form of RoboMusic. When Simon Kvamm and L.O.C. opened the rock museum - Danmarks Rockmuseum - in Roskilde the music was based on Centre for Playware’s concept of musical ”building blocks” enabling the user to in" uence and change the music through physical interaction with the music.

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 AutomationDESIGN Centre New research platform within electric technology: # e opening of our then newest centre, AutomationDESIGN PowerLabDK Centre, took place in September 2010 and was marked with a # is new research platform aims to bring Denmark into a seminar which featured contributions from several industrial leading position within intelligent electrical systems ensuring partners such as DONG Energy, NNE Pharmaplan and stability in the electricity supply of the future with emphasis ProInvent. on sustainable sources. Aim of this centre - which has been established as a joint A consortium with four partners form the back bone of research venture between IPU and DTU Electrical Engineering - is platform conducting research in areas such as “Smart Grids”. to act as gateway between industry, DTU researchers and Facilities range from " exible laboratories (DTU Electrical students by o& ering state-of-the-art laboratory facilities and Engineering and the Copenhagen University College of research within automation. Engineering) over large-scale experimental facility (Risø DTU) to a complete full-scale power system at Bornholm (Østkra$ – the Bornholm electrical utility company). Phase I is expected to be ful! lled by January 2011 as works in building 329 have begun and four EU tenders are currently being evaluated.

StaldTek – improving Danish pig stables # e Automation and Control group is one of the partners selected to take part in this innovative consortium supported by the Danish Agency for Science, Technology and Innovation. # e project deals with the development of pig stables including advanced, integrated robotics, which is the contribution by the Automation and Control Group. Other topics of the project are • Research and development through requirements and preferences of animals, sta! and the biological system • Modelling of air currents and emission of gases from surfaces with manure in pig stables • Biological control models for monitoring, stimulation and care of pigs in pig stables

# e project plan leads not only advanced sensor- and robot technology into the Danish pig stables. # e project breaks with the mindset of the existing technological solutions, which mostly are developed and adapted to the existing design of the stables from the 1970s.

# e project interacts with other applications projects within the following areas: feeding, cleaning, manure handling, stimulation and caring, management, planning and data Nordic Wind Power conference collection, climate and ventilation. Each application project # e 2009 Nordic Wind Power conference was held on represents a key function of daily operations of the pig stables, Bornholm in September 2009 focusing on: ”Power System and will lead to new solution concepts and become part of the Integration and Electrical Systems of Wind Turbines and robotic pig stable of the future. Wind Farms” Several sta& members of our Centre for Electric Technology gave lectures at the conference which was a% liated the climate conference COP15 held in December 2009 in Copenhagen.

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010 47

DTU ELECTRICAL ENGINEERING IN PROFILE 2010 Advisory board

Peter Petersen, Chief Technology O% cer Bang & Olufsen a/s

Poul To$ Frederiksen, Senior Science Advisor Grundfos A/S

Søren Westermann, Executive Vice President Widex A/S

Birgitte Brinch Madsen, Director Publications

Management 2009 2009 research data in numbers ISI registered journal papers 60 Professor Kristian Stubkjær Non ISI registered journal papers 13 Head of Department Conference papers published in journals 0 Professor Michael A.E. Andersen Conference papers published in books/proceedings 136 Deputy Head of Department Conference abstracts etc 10 Head of Electronics Chapters in books 2 Books 0 Associate Professor Finn Jacobsen Head of Acoustic Technology Reports 9 PhD theses 8 Associate Professor Ole Ravn MSc theses 91 Head of Automation and Control BSc theses 54 BEng theses 31 Professor Jørgen Arendt Jensen Head of Biomedical Engineering You may search for DTU Electrical Engineering’s Associate Professor Joachim Holbøll publications in DTU’s online research database, ORBIT. Head of Electric Components Website: http://orbit.dtu.dk Professor Jacob Østergaard Head of Electric Energy Systems If you use the advanced search mode, you can extract our publications. Professor Olav Breinbjerg Head of Electromagnetic Systems Links

Professor Torsten Dau For further information about DTU Electrical Engineering, Head of Hearing Systems you are welcome to visit our website. Here you will also ! nd our News & Events and Calendar containing daily updated Erik Sjønto$ information about DTU Electrical Engineering. Chairman of the DTU Electrical Engineering Study Committee Danish website: www.elektro.dtu.dk English website: www.elektro.dtu.dk/english

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DTU ELECTRICAL ENGINEERING IN PROFILE 2010