Real-time detection and extraction of visual features in wireless sensor networks is a challenging task due to its computational complexity and the limited processing power of the nodes. A promising approach is to distribute the workload to other nodes of the network by delegating the processing of different regions of the image to different nodes. In this work a solution to optimally schedule the loads assigned to each node is implemented on a real visual sensor network testbed. To minimize the time required to process an image, the size of the subareas assigned to the cooperators are calculated by solving a linear programming problem taking into account the transmission and processing speed of the nodes and the spatial distribution of the visual features. In order to minimize the global workload, an optimal detection threshold is predicted such that only the most significant features are extracted. The solution is implemented on a visual sensor network testbed consisting of BeagleBone Black computers capable of communicating over IEEE 802.11. The capabilities of the testbed are also extended by adapting a reliable transmission protocol based on UDP capable of multicast transmission. The performance of the implemented algorithms is evaluated on the testbed.

Geomagnetically induced currents (GIC) are a natural phenomenon which arises due to solar storms. During a solar storm, large amounts of magnetized plasma are ejected from the surface of the sun. When this plasma reaches earth, it causes fluctuations in the geomagnetic field. Such 　fluctuations may induce DC over-currents in long transmission lines. These currents affect the transmission system several dierent ways; In particular high voltage transformers are sensitive to GIC. When the over-current flows through the transformer windings the reactive power absorption of the transformer increases, which may lead to voltage instability in the power system. For this project, the main issue has been to determine whether or not an increase in the size of the transformer core leads to the reactive power absorption being less sensitive to GIC. In order to investigate this issue a recently developed transformer model has been used; the Hybrid transformer model. This model combines the principle of duality with a matrix representation of the transformer. The Hybrid transformer model, which has recently been implemented in the power system simulations software PSCAD, has been used to simulate GIC events in transformers of varying core sizes. The results from these simulations indicate that a larger transformer core is associated with a smaller increase in reactive power absorption during a GIC event. It is also clear that the reactive power absorption as a function of GIC magnitude is a non-linear function when the Hybrid transformer model is applied. This function has previously been considered a linear function. / Geomagnetiskt inducerade strömmar (GIC) är ett naturfenomen som uppstår till följd av solstormar. Vid en solstorm kastas stora mängder magnetiserad plasma ut från solens yta, och när denna plasma når jorden uppstår 　uktuationer i det jordmagnetiska fältet. Detta kan leda till att DCstr ömmar induceras i långa transmissionsledsningar. Dessa överströmmar påverkar kraftsystemet på 　era olika sätt, bland annat har de en stor påverkan på transformatorer. Då överströmmen 　yter genom transformatorlindningarna ökar det reaktiva eektuttaget för transformatorn, vilket kan leda till spänningsinstabilitet i systemet. En fråga som legat till grund för detta projekt är huruvida en ökning av transformatorkärnans storlek gör transformatorns reaktiva eektuttag mindre känsligt för GIC. För att undersöka detta har en ny transformatormodell använts; den såkallade hybridmodellen som kombinerar dualitetsprincipen med en matrisrepresentation av transformatorn. Denna modell, som nyligen implementerats i simuleringsprogrammet PSCAD, har använts för att simulera GIC i transformatorer med kärnor av olika storlekar. Resultaten från dessa simuleringar indikerar att större transformatorkärna medför mindre förändring av det reaktiva eektuttaget när transformatorn utsätts för GIC. Det är även tydligt att det reaktiva eektuttaget som funktion av GIC är en icke-linjär funktion när hybridmodellen används. Denna funktion har tidigare ansetts vara linjär.

In this project, we investigate automatic control of a quadrotor UAV and discuss its possible applications in the Smart Building. The purpose is to construct a control algorithm for stable quadrotor flight and explore the use of UAV in a smart home. We derive the equations of motion for a quadrotor, construct a model and devise a control strategy to keep it stable in the air. The strategy will be to use cascaded controllers for position and attitude. Simulations are performed and the controllers are then tested in practice. In the simulations, we use lead lag controllers as they provide easy loop shaping and good performance. In the practical implementation, we instead chose to implement PID controllers, due to their wide use in industry, easy implementation and ease of tuning. The end result is a stable loop with acceptable performance in terms of positional control. A simple waypoint system is implemented as well, which is key for trajectory planning and enables the vehicle to perform various tasks.

User written movie reviews carry substantial amounts of movie related features such as description of location, time period, genres, characters, etc. Using natural language processing and topic modeling based techniques, it is possible to extract features from movie reviews and find movies with similar features. In this thesis, a feature extraction method is presented and the use of the extracted features in finding similar movies is investigated. We do the text pre-processing on a collection of movie reviews. We then extract topics from the collection using topic modeling techniques and store the topic distribution for each movie. Similarity metrics such as Hellinger distance is then used to find movies with similar topic distribution. Furthermore, the extracted topics are used as an explanation during subjective evaluation. Experimental results show that our extracted topics represent useful movie features and that they can be used to find similar movies efficiently.

Performing visual feature extraction in a network of processing nodes is challenging and requires the development of algorithms that perform the allocation and delegation of computational tasks, of protocols responsible for the correct transmission of data, etc. This report starts working from the implementation of a testbed for the evaluation of distributed processing of visual features and extends its functionality. The testbed is implemented in C++ us- ing credit-card sized computers and ZigBee USB units. Communi- cation between nodes is carried out through ASN.1 defined types. The first part of the thesis work consists of enabling the system to work with two different feature extraction schemes. The first one is the already implemented SURF algorithm from OpenCV and the second one is the original implementation of BRISK. The user must be capable of choosing indifferently between them. The second part of the work consists of modifying the transmission aspects of the system including the necessary classes to provide reliability via the design of a retransmission protocol. The reliable transmission protocol used is a version of a Stop-and-Wait scheme. The system’s performance is evaluated detailing the time needed to complete each step of the feature extraction process, presenting a comparison between the SURF and BRISK detection and ex- traction times, and computing the frame loss rate and achievable throughput once the retransmission protocol is implemented.

This work investigated the effect of partial discharges (PD) on the complex permittivity of PVC, PC, PTFE, PE and PA6. The material samples were subjected to prolonged PD activity and the complex permittivity of the material was measured by dielectric spectroscopy (DS) before and after the sample was aged. The results showed a change in the loss factor for the tested materials, some were more affected than others and showed different behaviors when subjected to the PD aging. Hence it was not possible to find any general trend in the complex permittivity of the tested materials. Several of the materials exhibited a loss factor with -1/2 slope at low frequencies corresponding to diffusion. The -1/2 slope implies that the loss factor and the dynamic component of the real permittivity should be equal, which could not be seen. Therefore it is uncertain whether what was observed is a diffusion process or not. The results could suggest that PD aging causes a change in the trapping characteristics of the material. Furthermore, space charges deposited on the cavity wall from the PD activity could diffuse into the bulk of the material where some of the charges are trapped. If a DS measurement is performed before the trapped charges have had time to recombine or be conducted away, it could affect the complex permittivity. This was demonstrated by performing another DS measurement on an aged PC sample which had been left to rest for 35 days. The measurement showed that the complex permittivity had returned to almost the same state as before aging. Measurement problems were encountered which affected the measurements in this work. The problems are believed to be caused by the measurement electrodes used for the DS measurements not being heavy enough to eliminate small unwanted air-gaps between the electrodes and sample. Furthermore, incomplete results were obtained for some measurements which was believed to be due to the capacitance of the sample being at the limit of what the measurement instrument was able to measure. / Det här arbetet undersökte effekten av partiella urladdningar (PD) på den komplexa permittiviteten i PVC, PC, PTFE, PE och PA6. Materialproverna utsattes för långvarig PD aktivitet och materialets komplexa permittivitet mättes med hjälp av dielektrisk spektroskopi (DS) före och efter att provet åldrats. Resultaten visade en förändring i förlustfaktorn i de testade materialen, några påverkades mer än andra och de uppvisade olika beteenden när de blev utsatta för PD åldring. Det var därför inte möjligt att hitta någon generell trend i den komplexa permittiviteten för de olika testade materialen. Flera av materialen uppvisade en förlustfaktor med -1/2 lutning vid låga frekvenser vilket motsvarar diffusion. -1/2 lutningen medför att förlustfaktorn och den dynamiska komponenten av den reella permittiviteten borde sammanfalla, vilket inte kunde ses. Det är därför osäkert huruvida det som observerats är en diffusionsprocess eller inte. Resultaten kan tyda på att PD-åldring orsakar en förändring i potentialfällors egenskaper i materialet. Således skulle rymdladdningar som deponeras på väggarna i kaviteten på grund av PD-aktiviteten kunna diffundera in i materialet där en del av laddningarna fastnar. Om en DS mätning görs innan de fångade laddningarna har fått tillräcklig tid att rekombinera eller ledas iväg, kan det påverka den komplexa permittiviteten. Detta visades genom att genomföra en DS mätning på ett åldrat prov av PC som fått vila i 35 dagar. Mätningen visade att den komplexa permittiviteten hade återgått till nästan samma tillstånd som innan den åldrades. Mätproblem påträffades vilket påverkade mätningarna i detta arbete. Problemen antas vara orsakade av att mätelektroderna som användes till DS mätningarna inte var tillräckligt tunga för att eliminera små oönskade luftgap mellan elektroderna och provet. Dessutom erhölls ofullkomliga resultat för några av mätningarna vilket tros bero på att provets kapacitans befann sig på gränsen för vad mätinstrumentet kunde mäta.

Nowadays, we hear much about smart grids as a promising idea that will have a direct impact on our life of tomorrow. Research, articles and standards are also numerous on this subject. Among them, IEC 61850 is an important standard about communication which could have a big influence on electrical substations or even power plants in the future. However, the feasibility of this standard has been little investigated. This study has been done with Tractebel Engineering France, which is a branch of GDF Suez. They have good expertise on hydro power plant, but their projects can also cover electrical substations and electrical transmission lines. Smart grid’s development can have direct impacts on their activities. The study presents firstly the different aspects of smart grid, in order to know the logic of motivations and the interesting points for the company. A certain emphasis has been put on the electrical gird functioning aspect as well as renewable energies, because they seem to be especially important for Tractebel. Secondly, the study is focused on the main aim of this article, the feasibility of IEC 61850 to a substation of Tractebel’s Kaléta project. A presentation and analysis of essential notions of the standard 61850 has been done in chapter VII. In the following chapters, the study tries to make a judgment of the feasibility by analyzing the aspects of software, modeling and practical functioning of the substation. The study concludes that despite the fact that IEC 61850 seems to be the standard of the future, it is still premature today for Tractebel to use it in the case of Kaléta. Due to the independent software tools’ complexity and the lack of interoperability between different components, the modeling process remains complicated if we don’t want to choose a software program provided by a specific equipment supplier. Moreover, the functioning of an IEC 61850 substation requires new skills for the staff, which could be another practical problem for Kaléta.

Free Space Optical (FSO) communications are an emerging technology. Multiple resources around the world are being dedicated to the study and implementation of associated technologies. The possibility of high data rates, lower masses and more power efficient antennas are the expected advantages of these systems. However FSO channels are highly vulnerable. Atmospheric perturbations as well as pointing misalignments compromise the integrity of the transmitted data. Besides, current data protection architectures for FSO communication systems are not powerful enough to protect the data due to the nature of the perturbations. Therefore, Deutsches Zentrum für Luft- und Raumfahrt (DLR) is working on the implementation of a communication protocol (Laser Ethernet Transceiver protocol, LET) capable of transmitting high bit rates reliably. LET has to overcome the multiple errors induced by the disturbances in the channel (fades in the signal induced by the atmosphere and miss-pointing) and data stream misalignments during transmission. In addition, LET has to provide a framework for transmitting 1GbE (Gigabit Ethernet) payloads. Thus the focus of this MSc Thesis is on the definition and implementation of the abovementioned algorithms and hardware structures. These hardware structures are developed for their integration on Field Programmable Gate Arrays (FPGA) in VHDL language. At the end of this MSc Thesis, a significant improvement of 3.5 dB in the optical gain has been achieved with a Bit-Level Forward Error Correction (BLFEC) implementation. Some of the hardware structures have also been implemented and tested for the next steps. An analysis of the synchronization problems that will affect the system has been done and a technical solution has been provided. Additionally, an improvement of the channel throughput has been achieved in order to comply with the 1GbE Standard.

Smarta elnät är en av lösningarna för att uppnå EUs klimatmål den s.k. 20-20-20-satsningen. Klimatmålen innefattar bl.a. ökad energiproduktion från förnybara energikällor och ökad energieffektivisering, detta anses nödvändigt för att hindra den globala uppvärmningen samt uppnå en bättre och mer hållbar framtid.   Den elektriska energins svaghet är den begränsade möjligheten till effektiv och storskalig lagring. Eftersom den förnybara energin har en väderberoende produktion ska smarta elnät hjälpa konsumenten att styra energikonsumtionen efter hur energiproduktionen varierar. Det finns planer på ett smart elnät som genom att integrera avancerade informations- och kontrolltekniker ska samla in information från producenter och konsumenter för att sedan agera utifrån det "smartaste" alternativet. För att maximera användandet av den producerade förnybara energin kan en lösning vara att konstruera flera energilager där energi kan lagras under t.ex. blåsiga och soliga väderförhållanden. Vad som skulle kunna användas som energilager i framtiden är bl.a. elbilar och industrier. För implementering av smarta elnät är dynamic rating en viktig pusselbit. Med hjälp av sensorer ska information kunna mätas i realtid för att på så sätt maximera nyttjandegraden av energiproduktionen och elnätet.   Idag är Vecturas uppdrag inom elinfrastruktur till stor del inriktade på järnvägsanläggningar. Eftersom Vectura har en vilja att vidga sin verksamhet inom det elektrotekniska området finns ett intresse att bredda sig till andra områden inom elinfrastruktur t.ex. smarta elnät och dynamic rating. För att Vectura ska lyckas med denna uppgift är vidareutbildning av sina konsulter att rekommendera inom områdena: energilager, sensorer samt förnybar energi. Vattenkraft, vindkraft och solkraft är de viktigaste förnyelsebara energikällorna på svensk elmarknad. / Smart Grid is one of the solutions to achieve the European Union climate targets, "the 20-20-20- targets". These targets include e.g. higher energy-production from renewable sources and increased energy efficiency. The purpose of these targets is to prevent global warming in order to achieve a better and more sustainable future.   The weakness with electric energy is the limited possibility of effective and large-scale storage. With solar power plants and wind power plants, the energy will only be produced under favorable weather conditions. By using Smart Grid the energy consumption, the energy production and the grid can be controlled in a higher scale than today. This will be done by advanced information- and control-technology which will gather and act on information from suppliers and consumers and then act upon the "smartest" alternative. According to the power industry several energy storage units must be built due to store the energy in terms of maximize the benefits of renewable energy during windy or sunny weather, when renewable energy is produced as its best. Some experts in the field believe that electric cars or industries could be possible energy storage units. Another advantage with Smart Grid is the ability for consumers to produce their own electric energy and sell the surplus to the energy market. Dynamic Rating is an important part of the implementation of Smart Grid and can best be described with the words "increasing the level of utilization". By using sensors, information should be measured in real time to maximize the utilization rate of the energy production, the energy consumption and the grid.   Today, Vectura's mission in electricity infrastructure is largely focused on rail infrastructure. Now, they have a desire to extend their business in the field of electrical engineering, e.g. Smart Grid and Dynamic Rating. If Vectura will be able to start work on Smart Grids and Dynamic Rating in order to expand their business, training for its consultants is recommended in these areas: energy storage, sensors and renewable energy. Hydro power, wind power and solar power are the main renewable energy sources in the Swedish electricity market.

In this master thesis, a mathematical model of a hydraulic servo system for a manipulator robot is completed by using several different methodologies. The models proposed are particularly tuned for the DeLaval VMS robotic arm. The parameter identification of the robotic arm is accomplished by dividing the model into several subsystems and investigating each system separately by using catalogue data, experimental data and construction drawings. Furthermore, the assumptions are proposed based on the literature review and the expertise of in-house engineers. After completion of parameter identification several different mathematical models including linear and nonlinear methodologies are introduced. It is demonstrated that the improvednonlinear model can successfully mimic the movement of the robotic arm with relatively small errors and it is found to be fairly reliable. Moreover, the errors incurred when chamber pressures are compared with experimental data are found to be relatively small. Furthermore, the improved linear model have successfully delivered an accurate position estimation especially for the medium valve opening, while the chamber pressures are relatively less accurately predicted. The study further carries out sensitivity (uncertainty) analyses to investigate the crucial parameters of the model since it is sometimes very problematic to precisely estimate these parameters. It is found out that the flow coefficient and supply pressures have remarkable impact on the results of the simulations. Therefore, it is strongly advised that these parameters should be very carefully evaluated during the modeling process. Finally the bulk modulus models are compared and the influence of the bulk modulus is revealed.