En omställning till ett mer hållbart samhälle pågår både nationellt och internationellt. Arbete läggs på att öka andelen förnyelsebara energikällor där solceller är en populär produkt. När effekttopparna och de förnyelsebara energikällorna ökar i det svenska stamnätet så skapas ett behov av att lagra stora mängder energi. Att lagra den mängden energi i batterier skulle bli kostsamt. Resultatet från utredningen tyder på att vätgas är ett lämpligt alternativ då omvandlingsprocesserna genererar både elektrisk och termisk energi. Komponenterna som används är ursprungligen från industrin vilket gör dom överdimensionerade för vanliga hushåll. Optimalt används vätgassystem i flerfarmilsbostäder där både den termiska energin och elektriska energin kan nyttjas.

A Dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfillment of the requirements for the degree of Master of Science. Johannesburg, 2013 / Many of the problems in mathematics have very elegant solutions. As complex, real–world geometries come into play, however, this elegance is often lost. This is particularly the case with meshes of physical, real–world problems. Domain mapping helps to move problems from some geometrically complex domain to a regular, easy to use domain. Shape transformation, specifically, allows one to do this in 2D domains where mesh construction can be difficult. Numerical methods usually work over some mesh on the target domain. The structure and detail of these meshes affect the overall computation and accuracy immensely. Unfortunately, building a good mesh is not always a straight forward task. Finite Element Analysis, for example, typically requires 4–10 times the number of tetrahedral elements to achieve the same accuracy as the corresponding hexahedral mesh. Constructing this hexahedral mesh, however, is a difficult task; so in practice many people use tetrahedral meshes instead. By mapping the geometrically complex domain to a regular domain, one can easily construct elegant meshes that bear useful properties. Once a domain has been mapped to a regular domain, the mesh can be constructed and calculations can be performed in the new domain. Later, results from these calculations can be transferred back to the original domain. Using harmonic functions, source domains can be parametrised to spaces with many different desired properties. This allows one to perform calculations that would be otherwise expensive or inaccurate. This research implements and extends the methods developed in Voruganti et al. [2006 2008] for domain mapping using harmonic functions. The method was extended to handle cases where there are voids in the source domain, allowing the user to map domains that are not topologically equivalent to the equivalent dimension hypersphere. This is accomplished through the use of various boundary conditions as the void is mapped to the target domains which allow the user to reshape and shrink the void in the target domain. The voids can now be reduced to arcs, radial lines and even shrunk to single points. The algorithms were implemented in two and three dimensions and ultimately parallelised to run on the Centre for High Performance Computing clusters. The parallel code also allows for arbitrary dimension genus-0 source domains. Finally, applications, such as remeshing and robot path planning were investigated and illustrated.

Este trabalho apresenta o desenvolvimento de uma metodologia para a etiquetagem e qualificação de inversores para Sistemas Fotovoltaicos Conectados à Rede, com finalidade de servir de proposta de procedimento para inclusão no Regulamento de Avaliação de Conformidade de Equipamentos e Sistemas Fotovoltaicos do Programa Brasileiro de Etiquetagem. O procedimento desenvolvido avalia os inversores quanto à eficiência, qualidade de energia, proteções e informações operacionais e de instalação. / This work presents the development of a methodology for qualification and labeling of inverters for grid-connected photovoltaic systems, aiming serving as procedural proposal for inclusion in the Conformity Assessment Rules of Equipments and Photovoltaic Systems of the Brazilian Labeling Program. The developed procedure evaluates the inverters efficiency, power quality, protections and operational and installation information.

"This work addresses the problem of generating a 3D mesh grid model of a tree by a climbing robot for tree inspection. In order to generate a consistent model of the tree while climbing, the robot needs to be able to track its location while generating the model. Hence we explored this problem as a subset of Simultaneous Localization and Mapping problem. The monocular camera based Visual Simultaneous Localization and Mapping(VSLAM) algorithm was adopted to map the features on the tree. Multi-scale grid based FAST feature detector combined with Lucas Kande Optical flow was used to extract features from the tree. Inverse depth representation of feature was selected to seamlessly handle newly initialized features. The camera and the feature states along with their co-variances are managed in an Extended Kalman filter. In our VSLAM implementation we have attempted to track a large number of features. From the sparse spatial distribution of features we get using Extended Kalman filter we attempt to generate a 3D mesh grid model with the help of an unordered triangle fitting algorithm. We explored the implementation in C++ using Eigen, OpenCV and Point Cloud Library. A multi-threaded software design of the VSLAM algorithm was implemented. The algorithm was evaluated with image sets from trees susceptible to Asian Long Horn Beetle. "

Cells of the rodent medial entorhinal cortex (EC) possess cellular properties hypothesized to underlie the spatially periodic firing behaviors of 'grid cells' (GC) observed in vivo. Computational models have simulated experimental GC data, but a consensus as to what mechanism(s) generate GC properties has not been reached. Using whole cell patch-clamp and computational modeling techniques this thesis investigates resonance, rebound spiking and persistent spiking properties of medial EC cells to test potential mechanisms generating GC firing. The first experiment tested the voltage dependence of resonance frequency in layer II medial EC stellate cells. Some GC models use interference between velocity-controlled oscillators to generate GCs. These interference mechanisms work best with a linear relationship between voltage and resonance frequency. Experimental results showed resonance frequency decreased linearly with membrane potential depolarization, suggesting resonance properties could support the generation of GCs. Resonance appeared in medial EC but not lateral EC consistent with location of GCs. The second experiment tested predictions of a recent network model that generates GCs using medial EC stellate cell resonance and rebound spiking properties. Sinusoidal oscillations superimposed with hyperpolarizing currents were delivered to layer II stellate cells. Results showed that relative to the sinusoid, a limited phase range of hyperpolarizing inputs elicited rebound spikes, and the phase range of rebound spikes was even narrower. Tuning model parameters of the stellate cell population to match experimental rebound spiking properties resulted in GC spatial periodicity, suggesting resonance and rebound spiking are viable mechanisms for GC generation. The third experiment tested whether short duration current inputs can induce persistent firing and afterdepolarization in layer V pyramidal cells. During muscarinic acetylcholine receptor activation 1-2 second long current injections have been shown to induce persistent firing in EC principal cells. Persistent firing may underlie working memory performance and has been used to model GCs. However, input stimuli during working memory and navigation may be much shorter than 1-2 seconds. Data showed that input durations of 10, 50 and 100 ms could elicit persistent firing, and revealed time courses and amplitude of afterdepolarization that could contribute to GC firing or maintenance of working memory.

No description available.

Les systèmes pair-à-pair (P2P) sont utilisés par des millions d'usagers tous les jours. Dans beaucoup de cas, un usager souhaite communiquer, échanger du contenu ou des services à travers différents systèmes P2P. Cela requiert de la coopération entre les différents systèmes P2P, ce qui est très souvent difficile ou même impossible à obtenir, à cause des raisons suivantes; in primis, l'absence d'une infrastructure de routage entre les réseaux, ce qui rend la communication étanche et, in secundis, l'incompatibilité des protocoles et des opérations des susdits systèmes. L'objectif principal de cette thèse est celui de permettre la coopération entre systèmes P2P. La thèse introduit un cadre de coopération rétro-compatible entre systèmes P2P hétérogènes constitué de deux parties. La première est un cadre de routage intra-réseaux permettant à des réseaux hétérogènes de communiquer. La deuxième est une application coopérative, conçue à l'aide et au travers du cadre de routage, dont l'objectif est celui de résoudre les incompatibilités protocolaires des systèmes P2P sous-jacents. Comme étude de cas de notre cadre de coopération, on présente une solution complète permettant une coopération entre des réseaux P2P spécialisés dans l'échange des fichiers pouvant s'appliquer aux réseaux P2P actuels. Dans la deuxième partie de la thèse, on présente une étude de cas d'usage de notre architecture d'interconnexion des réseaux P2P pour la collecte et la gestion des données dans réseaux d'électricité intelligents. / Peer-to-peer systems are used by millions of users every day. In many scenarios, it is desirable for the users from different P2P systems to communicate and exchange content or services with each other. This requires co-operation between the P2P systems, which is often difficult or impossible, due to the two following reasons. First is the lack of an inter-overlay routing infrastructure throughout these systems, caused by the incompatibilities in overlay networks on top of which they are built. Second, there are incompatibilities in the application protocols of these systems. The main topic of this thesis is enabling the cooperation between P2P systems. The thesis introduces a cooperation framework for backward-compatible cooperating heterogeneous P2P systems which constitutes two parts. The first one is an inter-overlay routing framework which allows to inter-routing between heterogeneous overlay networks. The second one is the cooperation application, built on the top of the inter-overlay routing framework, which aims at solving the incompatibilities in the application protocols of P2P systems. As a case study of the cooperation framework, we introduce a complete solution for cooperating P2P file-sharing networks which is applicable for all current P2P file-sharing networks. In the second topic of this thesis, we investigate a case study of using inter-connecting P2P overlays for collecting and managing data in smart grid, a typical example of cyber physical system.

A crescente disponibilizaÃÃo de serviÃos atravÃs da Internet vem impondo uma demanda cada vez maior por recursos de processamento no lado servidor favorecendo a utilizaÃÃo dos Clusters de Computadores e das Grades Computacionais. Em paralelo, a engenharia de software traz novos paradigmas, como a OrientaÃÃo a ServiÃos, que impÃem novos desafios a serem tratados pelos fornecedores de serviÃos. A convergÃncia destes fatores deu origem as Arquiteturas de Grades Computacionais Orientadas a ServiÃos. Neste trabalho à apresentada uma proposta de arquitetura em grades computacionais orientada a serviÃos, denominada GDSAC (Grid â DiffServ Admission Control), que trata de aspectos ligados à QoS (Quality of Service) e a diferenciaÃÃo de serviÃos. A arquitetura G-DSAC à uma extensÃo da arquitetura WS-DSAC (Web Servers â DiffServ AdmissionControl). Està extensÃo compreende a concepÃÃo de uma soluÃÃo voltada para grades computacionais que à capaz de garantir os SLAs (Service Level Agreements) estabelecidos com os consumidores de serviÃos utilizando de forma otimizada os recursos de processamento disponibilizados na grade. A soluÃÃo permite ainda a diferenciaÃÃo de serviÃos no que diz respeito aos tempos de resposta oferecidos aos clientes, usuÃrios finais e serviÃos consumidores. A nova arquitetura introduz um bloco de funcionalidades em uma plataforma de grade computacional orientada a serviÃos formada por multclusters. Esse bloco permite a publicaÃÃo e localizaÃÃo de serviÃos, autenticaÃÃo e classificaÃÃo de requisiÃÃes e o escalonamento das mesmas dentro da grade de acordo com a classe de serviÃo a qual pertencem. Foi tambÃm implementado um protÃtipo que permitiu a realizaÃÃo de experimentos em uma plataforma real de testes visando avaliar a capacidade da soluÃÃo em atingir os objetivos por ela proposto

Este trabalho apresenta o desenvolvimento de uma metodologia para a etiquetagem e qualificação de inversores para Sistemas Fotovoltaicos Conectados à Rede, com finalidade de servir de proposta de procedimento para inclusão no Regulamento de Avaliação de Conformidade de Equipamentos e Sistemas Fotovoltaicos do Programa Brasileiro de Etiquetagem. O procedimento desenvolvido avalia os inversores quanto à eficiência, qualidade de energia, proteções e informações operacionais e de instalação. / This work presents the development of a methodology for qualification and labeling of inverters for grid-connected photovoltaic systems, aiming serving as procedural proposal for inclusion in the Conformity Assessment Rules of Equipments and Photovoltaic Systems of the Brazilian Labeling Program. The developed procedure evaluates the inverters efficiency, power quality, protections and operational and installation information.

O surgimento de volumes de dados na ordem de petabytes cria a necessidade de desenvolver-se novas soluções que viabilizem o tratamento dos dados através do uso de sistemas de computação intensiva, como o MapReduce. O MapReduce é um framework de programação que apresenta duas funções: uma de mapeamento, chamada Map, e outra de redução, chamada Reduce, aplicadas a uma determinada entrada de dados. Este modelo de programação é utilizado geralmente em grandes clusters e suas tarefas Map ou Reduce são normalmente independentes entre si. O programador é abstraído do processo de paralelização como divisão e distribuição de dados, tolerância a falhas, persistência de dados e distribuição de tarefas. A motivação deste trabalho é aplicar o modelo de computação intensiva do MapReduce com grande volume de dados para uso em ambientes desktop grid. O objetivo então é investigar os algoritmos do MapReduce para adequar a computação intensiva aos ambientes heterogêneos. O trabalho endereça o problema da heterogeneidade de recursos, não tratando neste momento a volatilidade das máquinas. Devido às deficiências encontradas no MapReduce em ambientes heterogêneos foi proposto o MR-A++, que é um MapReduce com algoritmos adequados ao ambiente heterogêneo. O modelo do MR-A++ cria uma tarefa de medição para coletar informações, antes de ocorrer a distribuição dos dados. Assim, as informações serão utilizadas para gerenciar o sistema. Para avaliar os algoritmos alterados foi empregada a Análise 2k Fatorial e foram executadas simulações com o simulador MRSG. O simulador MRSG foi construído para o estudo de ambientes (homogêneos e heterogêneos) em larga escala com uso do MapReduce. O pequeno atraso introduzido na fase de setup da computação é compensado com a adequação do ambiente heterogêneo à capacidade computacional das máquinas, com ganhos de redução de tempo de execução dos jobs superiores a 70 % em alguns casos. / The emergence of data volumes in the order of petabytes creates the need to develop new solutions that make possible the processing of data through the use of intensive computing systems, as MapReduce. MapReduce is a programming framework that has two functions: one called Map, mapping, and another reducing called Reduce, applied to a particular data entry. This programming model is used primarily in large clusters and their tasks are normally independent. The programmer is abstracted from the parallelization process such as division and data distribution, fault tolerance, data persistence and distribution of tasks. The motivation of this work is to apply the intensive computation model of MapReduce with large volume of data in desktop grid environments. The goal then is to investigate the intensive computing in heterogeneous environments with use MapReduce model. First the problem of resource heterogeneity is solved, not treating the moment of the volatility. Due to deficiencies of the MapReduce model in heterogeneous environments it was proposed the MR-A++; a MapReduce with algorithms adequated to heterogeneous environments. The MR-A++ model creates a training task to gather information prior to the distribution of data. Therefore the information will be used to manager the system. To evaluate the algorithms change it was employed a 2k Factorial analysis and simulations with the simulant MRSG built for the study of environments (homogeneous and heterogeneous) large-scale use of MapReduce. The small delay introduced in phase of setup of computing compensates with the adequacy of heterogeneous environment to computational capacity of the machines, with gains in the run-time reduction of jobs exceeding 70% in some cases.