Information Retrieval is a research area that has gained attention over thepast two decades. Few of these researches have taken place in the biomed-ical domain where satisfying users’ information needs are relatively difficultto be met. The goal of this project is to find out if it is possible to usestatistical methods in Biomedical Information Retrieval (IR) and improveretrieval performance, i.e. finding ways of fulfilling user information needs,in the biomedical domain using clustering with knowledge from the BioTracerproject.K-Mean and Expectation Maximization (EM) approaches to clustering havebeen implemented in this project with more emphasis on the EM. Both ap-proaches are used to re-ranking users searched results in an attempt to findways of fulfilling their information needs. Comparison between the Expec-tation Maximization and the K-mean are drawn in terms of their retrievalperformance i.e. precision and recall, the performance of EM compared to ex-isting approaches to search results re-ranking using clustering and problemsfaced while implementing the EM.

In this thesis a research on modern SiC semiconductor devices is made with a bias on the driving methods and requirements. A compact two-stage gate driver circuit for SiC VJFET is developed, the transistor is characterized and its gate requirements are estimated. The performance of developed driver is compared to the commercial SiC VJFET gate driver from SemiSouth. The conclusion is that both drivers behave similarly in switching the device in a half-bridge converter. In addition, the developed gate driver is a rather cheap solution compared to SemiSouth driver which is only available as engineering sample. Though, the optimization and especially shaping of the gate voltage/current waveforms must be done in order to extract the maximum performance of the SiC VJFET and obtain the lowest possible switching and on-state losses.Simulations are also carried out for validating the design of the board. The simulated circuit shows good correspondence with what was expected and described in scientific papers. The SiC BJT base driver circuit, which in addition was used to drive SiC MOSFET and SiC VJFET, is also characterized. The AC-coupled SiC BJT base drive circuit (section 3.6.3), which is also developed during the thesis, displayed a relatively good performance taken into account the simple design and cost effective nature of this driver.A characterization of different SiC transistors, i.e. SiC VJFET, SiC MOSFET and SiC BJT, is made. Two SiC Schottky diodes are also tested as the freewheeling diodes. Extensive experiments are performed on the developed half-bridge converter utilizing various combinations of SiC transistors, SiC diodes and gate/base driver circuits. The obtained results conclude that these new SiC transistors switch extremely fast and with relatively low energy losses, so that they can be used in high-frequency applications. Thus, converters that utilize SiC transistors can be made extremely compact. SiC BJT showed the best result with the highest switching speed and lowest energy losses compared to other two SiC transistors.

Modern electrical rail vehicles employ four-quadrant voltage source converters, which allow independent control of real and reactive power. This thesis focuses the control of reactive power at the vehicle regarding load flow and stability.Settings for power factor as a function of voltage were proposed in a project fall 2010, aiming to reduce line loss and increase transmission capacity. This thesis is mainly a further investigation of some of the settings proposed.One of the proposed settings for controlling reactive power is found to reduce the load of a rotary converter station in the range of 0-3 %. Total system losses are reduced by 0.21-0.33 %.During traction, the problematic issue regarding stability is found to be speed oscillations of the rotary converter. Controlling reactive power is found to have a limited damping effect on speed oscillations of a rotary converter. Other works have investigated how speed oscillations of the rotary converter can be damped by controlling the real power of the vehicle; the real power control is found to have a clearly better effect than reactive.During no-load operation, the problematic issue regarding stability is found to be oscillations caused by the vehicle and its control system. The vehicle control system and its response to the line voltage may cause instability, especially at long line lengths, regardless of any rotary converter. As reactive power has a significant effect on the line voltage, reactive power may be controlled in a manner increasing the damping of such oscillations significantly.Finally the thesis describes how a simulation model of a modern electrical rail vehicle for stability analysis can be made from the steady state characteristics and the input admittance of the vehicle, without knowing the complete vehicle model.The settings which where proposed and investigated in this project are optimized for a system fed by stiff voltage sources, not by rotary converters, and a more complete optimization for a system fed by rotary converters would be of interest.

Due to the advancements in graphical user interface design and modelingtechnology, model-based user interfaces are becoming more dynamic andmodeling frameworks allow developers to focus more on abstract modelingwhich means they can spend more time on user interface requirements ratherthan focusing model interpretation of executable user interfaces and howtheir codes are generated. Additionally, it can be noticed that the userinterfaces of desktop based applications are fairly faster, more responsive,and more ubiquitous as they are compared with the user interfaces of theirweb based counterparts, even though web based applications are evolvinggradually in the last decades. With the introduction of Ajax technology, userinterfaces of web based applications has become as dynamic as the ones in thedesktop based counterpars. By using this advantage of Ajax technology, themain objective is to implement support for modeling web browser-based userinterfaces to the existing work of Wazaabi project which is currently lack ofhandling them in an adequate way. To sum up, this master thesis describes acontribution to a new framework which is called Wazaabi by implementinga web browser modeling support to its already dened architecture that doesnot support modeling for web browser-based user interfaces as today.Keywords: User Interfaces, Modeling, Eclipse Modeling Framework, DeclarativeLive User Interface Models, Ajax Technology, Ajax Frameworks.

Reflecting on past experiences is crucial for learning from them and reconsider actions that have been taken in order to make better future choices. Different tools have been developed to support reflection both as an individual and collaborative activity. Aim of these tools is to provide individuals with information related to experience in order to make them reflect about it. However reflecting in a setting which is not the one where the object of reflection happened affects the reflective process due to the lack of the context in which the experience took place.This work aims at investigating how the usage of the Augmented Reality can be exploited in order to support reflection. In particular the main goal of the work is to study how Augmented Reality can trigger reflection on work practices that rely on deployment and management of resources in space.The outcome of this work is the analysis of a system that allows users to collect contextual information that has a strong spatial dimension and the design and implementation of an Augmented Reality application for tablet-device in order to visualize the information collected. A high level architecture of both the overall system and the prototype implemented is provided as well as storyboards for the solution proposal. The prototype implemented has been object of an experts evaluation in order to assess the potential usefulness of the application in real settings connected with the Italian Civil Defense. A workshop paper based on the work done in this thesis has been also written in concert with my supervisor Professor Monica Divitini and my co-advisor Simone Mora.

Student:Anders HammerSupervisor:Kjetil UhlenContact:Daniel MotaCollaboration with:Voith HydroProblem descriptionIEEE (Institute of Electrical and Electronics Engineers) presented in 2005 a new PSS structure named IEEE PSS4B (Figure 0 1). Voith Hydro wants to analyse the pros and cons of using this new type compared to older structures. The PSS4B is a multi-band stabilizer that has three separate bands and is specially designed to handle different oscillation frequencies in a wide range. Until now, Voith Hydro has used the common PSS2B in their installations, but in the future they will probably start to implement the new PSS4B. This master thesis will seek to find an answer on following questions:•How should the PSS4B be tuned to give the best damping of the local and inter-area oscillation mode?•Will an implementation of PSS4B give a better result compared to PSS2B?•What are the pros and cons of PSS2B and PSS4B? Figure 0 1: The multi-band stabilizer, IEEE PSS4B [1].MethodIn order to test and compare different PSS models, a simple two-area network model is created in a computer simulation programme (SIMPOW). One of the generating units is a hydro generator, which has a model of a static excitation system made by Voith Hydro. This network is characterised by a poorly damped inter-area oscillation mode, and in addition some local oscillation modes related to each machine. Different PSS structures (PSS2B and PSS4B) are then tuned and installed in the excitation system of the hydro generator, in order to improve the stability of the network. Different tuning methods of the PSS4B are designed, tested and later compared with the more common stabilizer the PSS2B. Simplifications are made where parts of the stabilizer is disconnected in order to adapt the control structure to the applied network and its oscillations. Totally 5 different tuning methods are presented, and all these methods are based on a pole placement approach and tuning of lead/lag-filters. ResultsInitial eigenvalues of the different setups are analysed and several disturbances are studied in time domain analysis, in order to describe the robustness of the system. Figure 2 illustrates the rotor speed of the generator, where the different PSS’s are implemented. PSS4B is clearly resulting in increased damping of all speed oscillations in this network. The same results can also be seen in an eigenvalue analysis.Conclusion The best overall damping obtained in this master thesis occurs when the high frequency band of the PSS4B is tuned first, and in order to maximize the damping of the local oscillation mode in the network. The intermediate frequency band is then tuned as a second step, according to the inter-area oscillation mode. Results of this tuning technique show a better performance of the overall damping in the network, compared to PSS2B. The improvement of the damping of the inter-area oscillation mode is not outstanding, and the reason is that the applied machine is relative small compared to the other generating units in the network. The oscillation modes in the network (local and inter-area) have a relative small frequency deviation. A network containing a wider range of oscillation frequencies will probably obtain a greater advantage of implementing a multi-band stabilizer.

The approaching of user satisfaction in Digital Media is raising new questions andchallenges in the interactivity relationship between creator and audience. In this workinteractivity is defined as a technology attribute that endows a media environmentwith the capability of reciprocal communication amidst user and technology throughthe technology. What are the key focus extents for managing technology based artproject? What I propose is a new layer of interaction, in which the user is viewed aspart of the interactive installation, being prompted by its pro-active behavior, redefininghim as a creative source. In this dimension, in addition to the language of the artist,what changes is also the perspective of use of the Work of Art: The user is now a livingpart of every creation, contributing to change each time the characteristics. Thanks totechnology, it becomes possible to completely revolutionize the way we conceive anddesign any type of cultural experience and to create spaces for an absolutely innovativeuse. This thesis will engineer the artistic Arduino based installation ArTime inorder to make it into a stable system that can function in museums and exhibitions,experimenting the new layer of interaction with scientific approaches.

Alot of research has been done on the rise of m-banking service in Kenya and most notably by Olga in her PHD theses and others and they all have research on how thriving the service is majorly attributed to the adoption and acceptance of the service through ease of use e.t.c.It can be noted that any service like such require ICT in place.Through use of ICT innovation in the mobile industry has grown especially with use of mobile phone to offer financial services in Kenya. Even though Kenya as a country is still lagging behind in other areas with growth and expansion of ICT when it comes to the mobile industry this is different and it is seen as a major leap to offering banking services without necessarily going to the bank. Understanding how the m-banking service is thriving and growing is far from just mere adoption and ease of use, with my thesis i try to analyze the challenges and opportunities that exist for the mobile industry in Kenya. I tackle m-banking service in particular and as can be noted no service can be allowed to operate without rules and regulations and as such what makes this service thrive if not the ICT policies in place and what strategies and practices employed by the mobile operators have worked for them.The research presented here is an interpretative study of the 4 mobile operators in Kenya.To maintain the subscribers the operators have to be innovative enough to create value added services in line with the regulations in place.

The objective of this thesis work has been to investigate the electric system stability, reliability and power security of an “off-grid” isolated network system integration of an offshore wind farm to offshore oil and gas platforms via HVAC transmission, considering different network topologies for wind power penetration, network losses, application of FACTS devices and different system voltage levels. The system stability studies were performed by steady state and dynamic simulations, analysing different perturbation events in the system. The power system model under study was established as a continuation of a previous work concerning a single platform system. The model can be seen to represent the Oseberg oilfield in the Norwegian Sea consisting of five offshore platforms. The complete model represents a grid integration of the five offshore platforms with a total load demand of 147MW to an offshore wind farm of 100MW production via HVAC as an isolated system. Wind farm capacity is less but of comparable size to the total load. Each platform has its own offshore power generation units (Gas Turbines - GTs) to cover the load demand at each platform. Load demands were selected based on recently collected real operational power consumption data from Statoil, ASA. In this study, 8 GTs were installed at different specific platforms to cope with the load of 150MW. Three different network topology configurations were considered, denoted Star, Star-F and Meshed. Four types of perturbation/disturbance events were analysed: Starting of 9MW asynchronous motor at Platform4, loss of a GT at Platform4, sudden loss of wind power production and loss of interconnection cable between Platform1 and Plaform4. The dynamic system stability was assessed by measuring frequency and voltage deviations at specific load buses to ensure whether transient deviations were following offshore NORSOK or IEC standards correctly or not. For each type of disturbances, different topology aspects were considered and analysed for different outages and different cases of percentage of wind power penetration. It could be seen that generators at platforms in all cases were able to regain synchronism by maintaining terminal voltage and power factor within allowed ranges after disturbances caused by Starting of 9MW motor, loss of wind power, loss of a GT and loss of cable. This can be explained because the isolated network system has a strong spinning reserve capacity. But not all studied scenarios were dynamically stable, following NORSOK standards for transient of voltage and frequency variations. The results showed the importance of an integrated grid system: Starting of big induction motor was found not to give large frequency or voltage deviations compared to the previous study of a single platform system since the integrated system has a larger inertia. Voltage deviations were found most critical in case of starting big motors. In addition, a meshed topology have better performace with less voltage and frequency deviation compared to the other two topologies for all perterbation events and cases. The results also showed that loss of wind power was more critical at high wind power penetration levels. A 100% sudden loss of wind power gave unacceptable frequency deviations. The study of two different voltage levels, 36kV and 52kV showed that a 52 kV network gave better dynamic stability behaviour compared to the other one. The study of FACTS devices applications showed that a STATCOM was more efficient in dynamic control of voltage than an SVC due to its better reactive power compensation capability at lower voltage, thus improving power transmission capability for the same power ratings.

The research work is aimed on the investigation of possible modeling and control schemes for the dc-link of VSC, with the purpose of identifying the impact of such modeling and control on the dynamics of the conversion system. A system consisting of back-to-back converters with equivalent grid interconnection and source representation is designed in the software PSCAD/EMTDC using a detailed switching model of the inverter and rectifier components. The control technique based on the well-established concept of vector control is implemented. The main task of the master thesis is oriented towards the achievement of more reliable dc-link dynamics with smaller required capacitance. The control algorithm is based on balancing the power between inverter and rectifier through the dc-link with the minimum dc voltage variations. Dc-link voltage regulation is achieved by implementing a control based on the energy stored in the dc-link capacitor. Alignment to a dq synchronous reference frame orientation with PI regulators is used in the control philosophy for decoupling purposes.