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Shaft current protection in hydro and turbo generators is an important generatorprotection issue. Currents owing in the generator shaft might damagegenerator bearings which, in turn, could reduce operating time and cause largenancial losses. Therefore, it is important to prevent operation of the generatorunder conditions of high shaft currents.In this project, task was to develop measurement and protection system thatis able to operate under certain conditions. Measurement device has to be ableto accurately measure currents lower than 1 A in a generator shaft that canvary in diameter from 16 cm up to 3 m. Also, those currents might appear infrequencies equal to multiples of line frequency. Device is to be located in alimited space and in a proximity of the generator. Thus, stray ux is expectedwhich might inuence measurements. Furthermore, since currents that haveto be measured are low, output of a measurement device is usually a low levelsignal. Such signal had to be catered for and adapted in a way that it can beused with numerical relay. After literature review and overview of possible solutions, Rogowski coil waschosen as the measurement device which will be further analysed. Two othercurrent transformers were considered which served as a good comparison withRogowski coil. Several dierent tests and measurements were made on mentionedmeasurement devices. Also, it was investigated how IEC61850-9-2 andMerging Unit (MU) could be used in this application. Upon this investigation,complete protection systems were assembled in the laboratory and they weretested. To asses the behaviour of dierent systems in the real environment, test installationwas built in the hydro power plant, Hallstahammar. This installationincluded traditional systems, with measurement signals connected to the relaya,and the one which utilized concepts of Process Bus and Merging Unit. Measurementsand tests that were made there served as a nal proof of successfulnessof protection systems. Results showed that Rogowski coil was a suitable choice for a measurementdevice due to its benecial mechanical and electrical properties. Also, tests madewith actual shaft current showed advantages of using Rogowski coil in pair withMerging Unit and process bus over traditional protection systems. Nevertheless,it was conrmed that both types of systems satisfy project requirements. / Skydd mot axelstrommar i vattenkraft- och turbo-generatorer ar mycket viktiga. Strommar kan uppkomma i generatoraxeln beroende pamagnetisk osymmetri istatorkarnan. Denna osymmetri ger upphov till en inducerad spanning i axelnsom sedan kan ge en axel-strom vid kortslutning av isolationen som rotornslager vilar pa. Om axel-strommen gar genom generatorns lager, kan lagretskadas allvarligt. Detta kommer i sin tur minska drifttiden och orsaka storaekonomiska forluster vid produktionsbortfall. Darfor ar det viktigt att detekteraom det gar axelstrommar genom generatorns lager. Examensarbetets mal var att utveckla ett mat- och skyddssystem for att detekteraaxel-strommar. Den matande enheten maste kunna detektera strommarmindre an 1 A i generatoraxeln vilken kan variera i diameter fran 16 cm upp till3 m. Dessutom kan dessa strommar ha frekvenser lika med eller multiplar avkraftnatets frekvens (50 eller 60Hz). Den matande enheten skall vidare kunnamonteras i ett trangt utrymme och i narhet av generatorns stator. Lackodefran statorn kan forvantas vara stort, och detta kan antas ha stor paverkanpamatningarna. Eftersom axelstrommen som mats ar lag, ar utsignalen franden matande enheten vanligtvis en lagnivasignal. Denna laga signalnivamasteanpassas saatt den kan anvandas i ett numeriskt rela, vilka vanligtvis kraverhogre energinivaer paingangsignalerna.Efter genomford litteraturstudie och oversikt over mojliga losningar, konkluderadesdet att en losning med Rogowski spole som matanordning borde varaintressant, och denna analyserades ytterligare. Tvastromtransformatorer medkonventionell konstruktion med karna av elektroplat valdes som jamforelse medlosningen baserad paRogowski spole. Flera olika tester och matningar gjordes. Dessutom undersoktes hur en process-bus losning enligt IEC61850-9-2LE meden Merging Unit (MU) skulle kunna anvandas i denna tillampning. Vid alladessa undersokningar har kompletta system for matning och skydd monteratsoch testats i laboratoriemiljo.For att registrera funktionen for de olika systemlosningarna i en verkligmiljo, monterades det kompletta systemet fran laboratorietesterna in i ett vattenkraftverki Hallstahammar. I detta vattenkraftverk ingar traditionella skydd-, styrnings- och kontroll-system och aven en aldre losning for att skydda generatornmot axelstrommar. Darmed kunde man jamfora prestanda mellan deolika losningarna baserade pastromtransformatorer av konventionell konstruktionmed karna av elektroplat och losningen med Rogowski spole. Signalerfran bada givarna anslots till ett numeriskt rela, och anslutning av Rogowskispolen gjordes aven via en MU till det numeriska relat. Matningar och testersom gjordes i kraftstationen kunde tas som ett slutligt bevis paatt de olikalosningarna baserade pa Rogowski spole ar en framtida losning for ett valfungerande axel-stroms skydd for generatorer. Resultaten visar att Rogowskispolen ar ett lampligt val aven med avseendepadess fordelaktiga mekaniska och elektriska egenskaper. Testerna som gjordesmed en verklig axel-strom visade tydligt fordelarna med att anvanda Rogowskispolen i kombination med MU och process bus jamfort med traditionella skyddssystem. Det ska dock understrykas att bade systemet med och det utan MUuppfyllde projektets krav.

ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada / This paper proposes a telemetering method consisting of delayed frame time diversity (DFTD) as the inner code and Reed-Solomon (RS) code as the outer code. DFTD is used to transmit a real-time frame together with a time-delayed frame which was saved in the memory during a defined period. The RS code is serially concatenated with DFTD. This method was applied to the design of telemetry units that have been used for over ten flight tests. The data results of the flight test for four cases with no applied code, with DFTD only, with the RS code only, and with both DFTD and the RS code are used to compare the number of error frames. The results also show that the proposed method is very useful and applicable to telemetry applications in a communication environment with a deep fade.

Doctor of Philosophy / Department of Industrial and Manufacturing Systems Engineering / Todd Easton / Integer Programming (IP) problems are a common type of optimization problem used to solve numerous real world problems. IPs can require exponential computational effort to solve using the branch and bound technique. A popular method to improve solution times is to generate valid inequalities that serve as cutting planes. This dissertation introduces a new category of cutting planes for general IPs called inequality merging. The inequality merging technique combines two or more low dimensional inequalities, yielding valid inequalities of potentially higher dimension. The dissertation describes several theoretical results of merged inequalities. This research applies merging inequalities to a frequently used class of IPs called multiple knapsack (MK) problems. Theoretical results related to merging cover inequalities are presented. These results include: conditions for validity, conditions for facet defining inequalities, merging simultaneously over multiple cover inequalities, sequentially merging several cover inequalities on multiple variables, and algorithms that facilitate the development of merged inequalities. Examples demonstrate each of the theoretical discoveries. A computational study experiments with inequality merging techniques using benchmark MK instances. This computational study provides recommendations for implementing merged inequalities, which results in an average decrease of about 9% in computational time for both small and large MK instances. The research validates the effectiveness of using merged inequalities for MK problems and motivates substantial theoretical and computational extensions as future research.

Heterogeneous platforms play an increasingly important role in modern computer systems. They combine high performance with low power consumption. From mobiles to supercomputers, we see an increasing number of computer systems that are heterogeneous. The most well-known heterogeneous system, CPU+GPU platforms have been widely used in recent years. As they become more mainstream, serving multiple tasks from multiple users is an emerging challenge. A good scheduler can greatly improve performance. However, indiscriminately allocating tasks based on availability leads to poor performance. As modern GPUs have a large number of hardware resources, most tasks cannot efficiently utilize all of them. Concurrent task execution on GPU is a promising solution, however, indiscriminately running tasks in parallel causes a slowdown. This thesis focuses on scheduling OpenCL kernels. A runtime framework is developed to determine where to schedule OpenCL kernels. It predicts the best-fit device by using a machine learning-based classifier, then schedules the kernels accordingly to either CPU or GPU. To improve GPU utilization, a kernel merging approach is proposed. Kernels are merged if their predicted co-execution can provide better performance than sequential execution. A machine learning based classifier is developed to find the best kernel pairs for co-execution on GPU. Finally, a runtime framework is developed to schedule kernels separately on either CPU or GPU, and run kernels in pairs if their co-execution can improve performance. The approaches developed in this thesis significantly improve system performance and outperform all existing techniques.

Malhas simpliciais são utilizadas em várias áreas da Computação Gráfica e Engenharia, como por exemplo, em vizualização, simulação, prototipação, além de outras aplicações. Este tipo de malha é, geralmente, utilizada como aproximações discretas de espaços contínuos, onde eles oferecem representações flexíveis e eficientes. Muito esforço é gasto visando gerar malhas de boa qualidade, porém, em alguns casos as malhas acabam sendo modificadas. Entretanto, este tipo de operação é geralmente custosa e inflexível, o que pode resultar na geraão de malhas bem diferentes das originais. A habilidade de manipular cenas dinâmicas revela-se um dos problemas mais desafiadores da computação gráfica. Este trabalho propõe um método alternativo para atualizar malhas simpliciais que vai além de mudanças geométricas e topológicas. Tal método explora uma das propriedade das Tringulações de Delaunay com Pesos, que permite a usá-las para definir implicitamente as relações de conectividade de uma malha. Ao contrário de manter as informações de conectividade explicitamente, a atual abordagem simplesmente armazena uma coleção de pesos associados a cada vértice. Além disso, criamos um algoritmo para calcular uma Tringulação de Delaunay com Pesos a partir de uma dada triangulação. O algoritmo consiste em uma busca em largura que atribui pesos aos vértices, e uma estratégia de de subdivisão para assegurar que a triangulação reconstruída será correspondente à original. Este método apresenta diversas aplicações e, em particular, permite a criação de um sistema simples de realizar combinação entre triangulações, que será ilustrada com exemplos em 2D e 3D. / Simplicial meshes are used in many fields of Computer Graphics and Engineering, for instance, in visualization, simulation, prototyping, among other applications. This kind of mesh is often used as discrete approximations of continuous spaces, where they offer flexible and efficient representations. Considerable effort is spent in generating good quality meshes, but in some applications the meshes can be modified over time. However, this kind of operation is often very expensive and inflexible, sometimes leading to results very different from the original meshes. The ability to handle dynamic scenes reveals itself as one of the most challenging problems in computer graphics. This work proposes an alternative technique for updating simplicial meshes that undergo geometric and topological changes. It explores the property that a Weighted Delaunay Triangulation (WDT) can be used to implicitly define the connectivity of a mesh. Instead of explicitly maintaining connectivity information, this approach simply keeps a collection of weights associated to each vertex. It consists of an algorithm to compute a WDT from any given triangulation, which relies on a breadth-first traversal to assign weights to vertices, and a subdivision strategy to ensure that the reconstructed triangulation conforms with the original one. This technique has many applications and, in particular, it allows for a very simple method of merging triangulations, which is illustrated with both 2D and 3d examples.

Nesta tese investiga-se uma nova abordagem visando implementar os conceitos propostos na Teoria da Evidencia para fins de classificação de imagens digitais em Sensoriamento Remoto. Propõe-se aqui a utilização de variáveis auxiliares, estruturadas na forma de Planos de Informação (P.I.s) como em um SIG para gerar dados de confiança e de plausibilidade. São então aplicados limiares aos dados de confiança e de plausibilidade, com a finalidade de detectar erros de inclusão e de omissão, respectivamente, na imagem temática. Propõe-se nesta tese que estes dois limiares sejam estimados em função das acurácias do usuário e do produtor. A metodologia proposta nesta tese foi testada em uma área teste, coberta pela classe Mata Nativa com Araucária. O experimento mostrou que a metodologia aqui proposta atinge seus objetivos. / In this thesis we investigate a new approach to implement concepts developed by the Theory of Evidence to Remote Sensing digital image classification. In the proposed approach auxiliary variables are structured as layers in a GIS-like format to produce layers of belief and plausibility. Thresholds are applied to the layers of belief and plausibility to detect errors of commission and omission, respectively on the thematic image. The thresholds are estimated as functions of the user’s and producer’s accuracy. Preliminary tests were performed over an area covered by natural forest with Araucaria, showing some promising results.

Weighted voting games are classic cooperative games which provide compact representation for coalition formation models in human societies and multiagent systems. As useful as weighted voting games are in modeling cooperation among players, they are, however, not immune from the vulnerability of manipulations (i.e., dishonest behaviors) by strategic players that may be present in the games. With the possibility of manipulations, it becomes difficult to establish or maintain trust, and, more importantly, it becomes difficult to assure fairness in such games. For these reasons, we conduct careful experimental investigations and analyses of the effects of manipulations in weighted voting games, including those of manipulation by splitting, merging, and annexation . These manipulations involve an agent or some agents misrepresenting their identities in anticipation of gaining more power or obtaining a higher portion of a coalition's profits at the expense of other agents in a game. We consider investigation of some criteria for the evaluation of game's robustness to manipulation. These criteria have been defined on the basis of theoretical and experimental analysis. For manipulation by splitting, we provide empirical evidence to show that the three prominent indices for measuring agents' power, Shapley-Shubik, Banzhaf, and Deegan-Packel, are all susceptible to manipulation when an agent splits into several false identities. We extend a previous result on manipulation by splitting in exact unanimity weighted voting games to the Deegan-Packel index, and present new results for excess unanimity weighted voting games. We partially resolve an important open problem concerning the bounds on the extent of power that a manipulator may gain when it splits into several false identities in non-unanimity weighted voting games. Specifically, we provide the first three non-trivial bounds for this problem using the Shapley-Shubik and Banzhaf indices. One of the bounds is also shown to be asymptotically tight. Furthermore, experiments on non-unanimity weighted voting games show that the three indices are highly susceptible to manipulation via annexation while they are less susceptible to manipulation via merging. Given that the problems of calculating the Shapley-Shubik and Banzhaf indices for weighted voting games are NP-complete, we show that, when the manipulators' coalitions sizes are restricted to a small constant, manipulators need to do only a polynomial amount of work to find a much improved power gain for both merging and annexation, and then present two enumeration-based pseudo-polynomial algorithms that manipulators can use. Finally, we argue and provide empirical evidence to show that despite finding the optimal beneficial merge is an NP-hard problem for both the Shapley-Shubik and Banzhaf indices, finding beneficial merge is relatively easy in practice. Also, while it appears that we may be powerless to stop manipulation by merging for a given game, we suggest a measure, termed quota ratio, that the game designer may be able to control. Thus, we deduce that a high quota ratio decreases the number of beneficial merges.

The explosion of internet traffic, advent of social media sites such as Facebook and Twitter, and increased availability of digital cameras has saturated life with images and videos. Never before has it been so important to sift quickly through large amounts of digital information. Salient Object Detection (SOD) is a computer vision topic that finds methods to locate important objects in pictures. SOD has proven to be helpful in numerous applications such as image forgery detection and traffic sign recognition. In this thesis, I outline a novel SOD technique to automatically isolate important objects from the background in images.

<p>Due to the explosion of the amount of biomedical data, knowledge and tools that are often publicly available over the Web, a number of difficulties are experienced by biomedical researchers. For instance, it is difficult to find, retrieve and integrate information that is relevant to their research tasks. Ontologies and the vision of a Semantic Web for life sciences alleviate these difficulties. In recent years many biomedical ontologies have been developed and many of these ontologies contain overlapping information. To be able to use multiple ontologies they have to be aligned or merged. A number of systems have been developed for aligning and merging ontologies and various alignment strategies are used in these systems. However, there are no general methods to support building such tools, and there exist very few evaluations of these strategies. In this thesis we give an overview of the existing systems. We propose a general framework for aligning and merging ontologies. Most existing systems can be seen as instantiations of this framework. Further, we develop SAMBO (System for Aligning and Merging Biomedical Ontologies) according to this framework. We implement different alignment strategies and their combinations, and evaluate them in terms of quality and processing time within SAMBO. We also compare SAMBO with two other systems. The work in this thesis is a first step towards a general framework that can be used for comparative evaluations of alignment strategies and their combinations.</p> / Report code: LiU-Tek-Lic-2006:6.