This thesis comprises two parts: the first part presents channel-adaptive techniques to achieve high spectral efficiency in a single user multiple-input multiple-output (MIMO) system; the second part exhibits a programmable and reconfigurable software-defined-radio orkbench(SDR-WB) in the Matlab/Octave environment that accommodates a variety of wireless applications. In an attempt to achieve high spectral efficiency, an adaptive modulation technique is applied at the transmitter to vary the data rate depending on the channel state information (CSI). To further enhance the spectral efficiency, adaptive power allocation schemes are applied in the spatial domain to adjust the power on every transmit antenna. We analyze several power control schemes subject to a peak power constraint to maximize the spectral efficiency given an instantaneous target bit-error-rate (BER). A novel power allocation trategy is proposed to achieve high spectral efficiency with relatively low complexity. In addition, adaptive techniques that switch across different MIMO schemes enables even higher spectral efficiency by choosing the scheme with the highest spectral efficiency. We propose a new method to switch between spatial multiplexing with zero-forcing (ZF) detection and orthogonal space-time block coding (OSTBC). This is done by exploiting closed form expressions of the spectral efficiencies--discrete rate spectral efficiency--and finding the crossing points of the two curves. The proposed adaptation scheme adds limited complexity to the transmitter since it requires only statistical information of the channel, which does not change as time evolves. Software Defined Radio (SDR) has received more and more interest recently as a promising multi-band multi-standard solution for transceiver design. In order to support as many wireless applications as possible, we build up a programmable and reconfigurable workbench, namely SDR-WB, in Matlab/Octave environment. The workbench is functionally modularized into generic blocks to facilitate fast development and verification of new algorithms and architectures. The modulation formats that are currently supported by the SDR-WB are MIMO, Orthogonal frequency-division multiplexing (OFDM), MIMO-OFDM, DS-CDMA and Filtered Multitone (FMT). / QC 20101108

This licentiate thesis describes the modeling and measurements performed with the aim of developing design guidelines for Line Start Permanent Magnet Synchronous Motors, LSPMSMs. LSPMSMs can offer higher efficiency than standard induction motors used in the industry today, especially for small motor sizes. The increase in efficiency results in lower environmental impact and reduced electricity cost. The LSPMSM has, however, several drawbacks, among the most important is the reduced starting capability compared to induction motors. Furthermore, the rotor construction is complex and the added cost of magnet material makes the LSPMSM a comparably expensive motor type. The design of a LSPMSM is a trade-off between starting capability and steady state performance. The thesis discusses these trade-offs and the models that can be used as a basis for design and optimization. The models make use of different motor parameters, and a number of measurement methods for measuring these parameters are described and compared. Among these is a step response adapted measurement method that provides most of the parameters of interest. The development and setup of a brake bench for measuring both start-up and steady state performance is presented. Furthermore the start-up behavior and steady-state performance is calculated using measured parameters. The calculated performance is compared to measured performance and found to correlate well for nominal operating conditions. Thus, design guidelines can be based on the models proposed. / QC 20101112

Unforeseen changes in production or consumption in power systems lead to changes in grid frequency. This can cause damages to the system, or to frequency sensitive equipment at the consumers. The system operator (SO) is the responsible for balancing production and consumption in the system. The regulating market is the market place where the SO can sell or purchase electricity in order to balance unforeseen events. Producers acting on the regulating market must be able to change their production levels fast (within minutes) when required. Hydropower is therefore suitable for trading on the regulating market because of its flexibility in power production. This thesis describes models that hydropower owners can use to generate optimal bidding strategies when the regulating market is considered. When planning for trading on the market, the prices are not known. Therefore, the prices are considered as stochastic variables. The planning problems in this thesis are based on multi-stage stochastic optimization, where the uncertain power prices are represented by scenario trees. The scenario trees are generated by simulation of price scenarios, which is achieved by using a model based on ARIMA and Markov processes. Two optimization models are presented in this thesis: * Model for generation of optimal bidding strategies for the regulating market. * Model for generation of optimal bidding strategies for the spot market when trading on the regulating market is considered. The described models are applied in a case study with real data from the Nordic power system. Conclusions of the thesis are that the proposed approaches of modelling prices and generation of bidding strategies are possible to use, and that the models produces reasonable data when applied to real data. / Oväntade produktions- eller konsumtionsändringar i kraftsystem leder till ändringar i nätfrekvens. Detta kan orsaka skador på systemet eller på frekvenskänslig utrustning hos konsumenterna. Systemoperatören (SO) är den ansvarige för att balansera produktion och konsumtion i kraftsystemet. Till sin hjälp har SO reglermarknaden, som är den handelsplats där SO köper eller säljer el för att balansera oväntade händelser i systemet. Producenter som agerar på reglermarknaden måste snabbt (inom minuter) kunna ändra sina produktionsnivåer om så behövs. Vattenkraft är därför lämplig för handel på reglermarknaden på grund av dess flexibilitet i kraftproduktion. Denna avhandling beskriver modeller som vattenkraftägare kan använda för generering av optimala budstrategier då reglermarknaden beaktas. När en producents planering för handel på marknaden utförs är marknadspriserna okända. Dessa är därför betraktade som stokastiska variabler. Planeringmodellerna som presenteras i denna avhandling är baserade på multi-periodisk stokastisk programmering, där de osäkra marknadspriserna är representerade av ett scenarieträd. Scenarierna i trädet genereras genom simulering av marknadspriser. En prismodell, baserad på ARIMA- och Markovprocesser, har därför utvecklats. Två olika optimeringsmodeller presenteras i denna avhandling: * Model för generering av optimala budstrategier för reglermarknaden. * Model för generering av optimala budstrategier för spotmarknaden då handel på reglermarknaden beaktas. Modellerna tillämpas i en studie där data från den nordiska elmarknaden appliceras. Slutsatser i avhandlingen är att de föreslagna ansatserna för modellering av priser och generering av budstrategier är möjliga att anvÄanda, samt att modellerna producerar rimliga resultat när applicerade på verkliga data. / QC 20101217

Orthogonal Frequency Division Multiplexing (OFDM) is well known as an efficient technology for wireless communications and is widely used in many of the current and upcoming wireless and wireline communication standards. However, it has some intrinsic drawbacks, e.g., sensitivity to the inter-carrier interference (ICI) and high peak-to-average power ratio (PAPR). Additionally, the cyclic prefix (CP) is not spectrum efficient and fails when the channel delay spread exceeds the length of CP, which will result in inter-symbol interference (ISI). In order to combat or alleviate these drawbacks various techniques have been proposed, which can be categorised into two main classes: techniques that keep the structure of OFDM and meanwhile increase the system robustness or re-organise the symbol streams on each sub-carrier, and techniques that increase the ISI/ICI immunity by adopting well designed pulse shapes and/or resorting to general system lattices. The latter class are coined as Generalised FDM (GFDM) throughout this thesis to distinguish with the former class. To enable seamless handover and efficient usage of spectrum and energy, GFDM is expected to dynamically adopt pulse shapes that are optimal in doubly (time and frequency) dispersive fading channels. This is however not an easy task as the method of optimal pulse shape adaptation is still unclear, let alone efficient implementationmethods. Besides, performance of GFDM highly depends on the channel estimation quality, which is not straightforward in GFDM systems. This thesis addresses, among many other aspects of GFDM systems, measures of the time frequency localisation (TFL) property, pulse shape adaptation strategy, performance evaluation and channel estimation.  We first provide a comparative study of state-of-the-art GFDM technologies and a brief overview of the TFL functions and parameters which will be used frequently in later analysis and discussion. A framework for GFDM pulse shape optimisation is formulated targeting at minimising the combined ISI/ICI over doubly dispersive channels. We also propose a practical adaptation strategy utilising the extended Gaussian functions (EGF) and discuss the trade-off between performance and complexity.  One realisation under the umbrella of GFDM, namely OFDM/OQAM, is intensively studied and an efficient implementation method by direct discretisation of the continuous time model has been proposed.  Besides, a theoretical framework for a novel preamble-based channel estimation method has been presented and a new preamble sequence with higher gain is identified. Under the framework, an optimal pulse shape dependent preamble structure together with a suboptimal but pulse shape independent preamble structure have been proposed and evaluated in the context of OFDM/OQAM. / QC 20101108

This thesis presents work performed on explosively driven magnetic flux compression generators. This kind of devices converts the chemically stored energy in a high explosive into electromagnetic energy in the form of a powerful current pulse. The high energy density of the high explosives makes flux compression generators attractive as compact power sources. In order to study these devices a generator was designed at FOI in the mid-90ies. Two generators remained unused and became available for this licentiate work. The thesis reports experiments with, and simulations of, the operation of the two remaining generators. The aim was to fully understand the performance of the generator design and be able to accurately simulate its behaviour. The generators were improved and fitted with various types of diagnostics to monitor the generator operation. Two experiments were performed of which the first generator was operated well below its current capability limits while the second was stressed far above its limits. Since the generator generates a rapidly increasing current, a current measurement is the most important diagnostic revealing the current amplification of the generator and its overall performance. Further it is important to measure the timing of various events in the generator. With a common time reference it is possible to combine data from different probes and extract interesting information which cannot be directly obtained with a single measurement. Two types of numerical simulations have been performed: Hydrodynamic simulations of the high explosive interaction with the armature were used to verify the measured armature dynamics. A zero-dimensional code was used to perform circuit simulations of the generator. The model takes into account the inductance reduction due to the compression of the generator as well as the change in conductivity due to heating of the conductors in the generators. / QC 20101103

In today's society, technology that does not have integrated app control or digital control is considered outdated. In fact, the technological growth of new features and innovations has grown exponentially over the past 100 years. This rapid development makes it difficult for manufacturers of larger products and machinery to keep up, both due to time constraints and economic reasons. The purpose of the thesis was to evaluate the benefits of digitalizing the electrical system in a vehicle, as well as developing a demorig with accompanying electrical architecture that demonstrates its feasibility. During the course of the work, it became clear that the major benefits of digitalizationwere a reduction in errors and malfunctions, while increasing flexibility and communication capabilities. Finally, a fully functional solution was presented that was tailored to meet the requirements of Volvo Trucks, with the goal of being implemented in the next version of their Crew Cab. The logic behind the system was functionally tested in a demo rig that included all components from the cab. The project demonstrated a significant reduction in cabling with the ability to control components with high precision through pulse width modulation signals and transistors.

This thesis introduces a coding scheme for very low bitrate video coding through the aid of principal component analysis. Principal information of the facial mimic for a person can be extracted and stored in an Eigenspace. Entire video frames of this persons face can then be compressed with the Eigenspace to only a few projection coefficients. Principal component video coding encodes entire frames at once and increased frame size does not increase the necessary bitrate for encoding, as standard coding schemes do. This enables video communication with high frame rate, spatial resolution and visual quality at very low bitrates. No standard video coding technique provides these four features at the same time. Theoretical bounds for using principal components to encode facial video sequences are presented. Two different theoretical bounds are derived. One that describes the minimal distortion when a certain number of Eigenimages are used and one that describes the minimum distortion when a minimum number of bits are used. We investigate how the reconstruction quality for the coding scheme is affected when the Eigenspace, mean image and coefficients are compressed to enable efficient transmission. The Eigenspace and mean image are compressed through JPEG-compression while the while the coefficients are quantized. We show that high compression ratios can be used almost without any decrease in reconstruction quality for the coding scheme. Different ways of re-using the Eigenspace for a person extracted from one video sequence to encode other video sequences are examined. The most important factor is the positioning of the facial features in the video frames. Through a user test we find that it is extremely important to consider secondary workloads and how users make use of video when experimental setups are designed.

Den här rapporten utreder förutsättningarna för att konstruera om ett mindre distributionsnät på 10 kV i Stockholms skärgård till ett så kallat smart nät med självläkande funktion. Nätet är avlägset och har haft många fel de senaste åren, därför är det önskvärt att kunna lokalisera fel i nätet och automatiskt koppla om till rundmatning direkt ifrån driftcentralen för att minska avbrottstiden för de boende på öarna. Rapporten fokuserar speciellt på att utreda lämpligheten med att använda feldetekteringsutrustningen SICAM FCM i nätet och hur dessa bör ställas in. Information om det aktuella nätet och problemet beskrivs tillsammans med en teoretisk bakgrund. Resultat ifrån tester och felsimuleringar på SICAM FCM med fokus på känslighet kring tröskelvärden presenteras och analyseras. Utifrån testresultat och information om nätet har rekommenderade inställningar för SICAM FCM tillsammans med andra rekommendationer för implementeringen av det självläkande nätet tagits fram. / This report has investigated the conditions for reconstructing a small 10 kV distribution grid in the Stockholm archipelago into a so called smart grid with a self-healing function. The grid is in a remote location and have had a lot of faults during the last years, therefore it is desirable to be able to locate the fault and automatically section it and restore service through a back-up feeder (if needed) to reduce downtime for customers. This report focuses especially on the suitability to use the fault detection equipment SICAM FCM in the grid and to propose how it should be configured. Information about the grid and problem is described together with a theoretical background. The results from tests and fault simulations on the SICAM FCM focused on sensibility around threshold values is presented and analysed. From test results and information about the grid recommended settings for SICAM FCM together with other recommendations for implementation of the self-healing grid has been produced.

Nu för tiden kablifieras nätet, vilket innebär att allt fler luftledningar ersätts med markkabel, en följd av stormar som åstadkommit stora och långa avbrott i nätet. Egenskaperna i elnätet förändras på grund av kablifieringen och beräkningarna för reläskyddsinställningarna för de riktade jordströmsskyddet som görs idag behöver därför ses över om de fortfarande kan utföras på samma sätt som tidigare. Detta för att säkerställa korrekt och selektiv felbortkoppling i händelse av fel. I föreliggande rapport förklaras i förenklade drag hur resistiva nollföljdsströmmar rör sig i nätet och hur de mäts in av jordfelsskydd. Ett fiktivt 22 kV nät har studerats och jordfel på två olika ledningar i detta nät analyseras och diskuteras. Beräkningar görs med olika storlekar på nollpunktsmotstånd samt olika höga resistiva nollföljdsbidrag från ledningarna vilket ger olika resistiva nollföljdsströmmar i nätet. Detta görs i både normaldrift och i reservdrift för att kunna studera vilka skillnader som faktiskt kan uppkomma. Diskussion sker om vad som hänt om hänsyn tagits till snedavstämning, obalans, vinkelfel och mätfel, vilket beräkningarna i detta arbete inte gör. Slutsatsen som dras av den utförda studien är att det är svårt att ställa in riktade jordströmsskydd samt nollpunktsspänningsskydd för att kunna säkerställa korrekt bortkoppling vid både normal- och reservdrift. Detta på grund av de olika resistiva nollföljdsströmmarna som uppkommer i nätet. / Today more and more overhead lines are replaced by underground cables as a result of storms which have caused major interruptions in the power grid. Because of the cabling, the characteristics of the power grid change and the calculations for the relay protection settings that are made today need to be reviewed if they still can be performed in the same way as before. This to ensure correct and selective fault disconnection. This report, in a simplified way, explains how resistive zero-sequence currents flow in the grid and how they are measured by earth fault protection. A fictitious 22 kV grid has been studied and earth faults on two different cables in the grid are analyzed and discussed. Calculations are made with different sizes of the zero-point resistance resulting in different resistive zero-sequence currents in the grid. This is done both in normal operation and reserve power operation to be able to study differences that can occur. Discussions are made regarding misalignment, imbalance, angle error and measurement error, which have not been included in this work. The conclusion from the study performed is that it is difficult to parameterize a directional earth fault protection and a zero-point voltage protection correctly to be able to secure a correct disconnection in both normal and backup operation. This is because of the various resistive zero-sequence currents that arise in the grid.

Directional couplers are passive components in radio frequency (RF) engineering and have a broad set of applications. With the scope of how a directional coupler can be implemented in a design, it is important to have specified goals in mind when designing a coupler, for the component to be precise and behave in a desired way. Different design variations also have benefits and disadvantages, and in this project several variations of couplers were investigated. The limiting factors in this project were the rather small area to work with, combined with the design requirements. This is ultimately what made the design approach unique and the reason for using an iterative process in a simulation software, where conventional methods of designing could not be used. Out of the different designs that were tested, two directional couplers on the RO4350B substrate with a gap of 0.34 mm between the transmission lines fulfilled every design parameter except the one regarding the coupling factor. There are three notable conclusions that were drawn. The first is that all directivity compensation methods that were evaluated are valid after optimizing relevant parameters. Some methods could be combined to have an even greater effect, such as the soldermask and wiggly line methods. The second is that ground vias can affect the directivity of a directional coupler substantially. Designing a coplanar waveguide coupler can also have benefits in respect to the given design requirements in this project. Thirdly, a lossy material such as FR4 could be used and still achieve the design parameters at these frequencies.