Existing low-voltage networks may not accommodate high penetrations of low-carbon technologies. The topic of this thesis is unbalance, which if minimised can delay or avoid the constraining of these technologies or the replacing of still-useful network assets. Most of the discussion on unbalance, as seen in the standards and the literature, centres on the effects of voltage unbalance on consumer equipment. Its effects on the network are not equally reported. This thesis recognises fundamental differences between the consumer and network perspectives. It can inform distribution network operators on the interpretation of measurements taken on low-voltage networks and guide research on unbalance due to high penetrations of low-carbon technologies. Much of the work involved simulations of LV networks. Initially, existing 3 x 3 or 5 x 5 approaches to the forward-backward sweep method were thought suitable. After a review of these approaches however, there were doubts as to how accurately they accounted for the shared neutral-earth return path on which the out-of-balance current flows. This led to the derivation of a new 5 x 5 approach using only Kirchhoff s voltage (KVL) and current laws (KCL). Its results are validated thoroughly in the thesis. In addition to satisfying KVL and KCL, they match Matlab SimPowerSystems exactly and are in close agreement with measurements taken on a very unbalanced rural feeder. This thesis also investigates the mitigation of unbalance using the static balancer. This is a transformer with a single interconnected-star winding. It was used in 1930-1950s to correct unbalance. Contributions are made for its possible re-introduction as a retrofit option. They include a model for use in the forward-backward sweep method, validated by laboratory and field measurements, and the quantification of the static balancer s strengths and weaknesses as this can help identify when it should be used.

Data Plane Development Kit is a highly used library for creating network applications that can be run on all hardware. Data Plane Development Kit has a component called Service Cores, which allows the main applications to create services that will run independently. These services are manually mapped to specific CPU cores, and are scheduled in a round-robin method. Because of the manual mapping, and the scheduling, the different load for each service can impact the start time for each service. By having services not run when supposed to, the throughput will degrade. In this thesis, we investigate and try to solve the issue by implementing a basic load balancer into the Service Core component. Our results show that an basic load balancer, that will balance upon reaching a CPU upper threshold, will increase the throughput of services while decreasing the delay between each service run.

A manipulação de materiais é uma das tarefas em que comumente empregam-se robôs para substituir o trabalho humano, dadas algumas vantagens como: maior precisão na manipulação de cargas e maior velocidade de execução da tarefa, bem como por aumentar a segurança do operador. Apesar dessas vantagens, os dispositivos robóticos são largamente empregados apenas em situações em que velocidade e precisão são indispensáveis, em outros casos, os equipamentos convencionais (como talhas, gruas e macacos hidráulicos) e os dispositivos específicos (aqueles fazem uso de molas e contrapesos), vêm sendo utilizados nas tarefas cotidianas, principalmente pelo fato de, entre outros, serem menos dispendiosos. Comparando-se estas duas soluções disponíveis, tem-se que os equipamentos tradicionais, apesar de sua simplicidade e versatilidade de movimentação, apresentam limitações quando são exigidas precisão e eficiência, enquanto os dispositivos robóticos apresentam alta complexidade tanto no projeto quanto na operação, representando uma solução cara e com movimentação restrita pela programação. Neste contexto, o presente trabalho tem por objetivo estudar e propor uma solução intermediária entre a solução convencional e a robótica. O foco do estudo é o projeto de um dispositivo simplificado, que faz uso de molas e de um sistema de alavanca para manipular cargas. Um estudo preliminar desse mecanismo mostrou imperfeições quanto à força de contrabalanceamento. Com o intuito de corrigir esse erro foi usado um sistema de controle, que é constituído por um motor elétrico, um mecanismo de correção, sensores e um módulo controlador. O dispositivo proposto apresenta um controle simplificado, vez que a movimentação é feita exclusivamente pelo operador, possibilitando assim que o dispositivo apresente um baixo consumo de energia. Um protótipo é desenvolvido e os testes demonstraram a eficácia da solução. / The material handling is one task in which robot is commonly employed to replace the human work because it has some advantages such as, higher precision in the handling and higher speed of the task, and to increase operator safety. Despite these advantages, the robotic device is most employed only in situation that speed and precision are essential; in other cases, the conventional equipments (such as hydraulic jacks, cranes and pulley systems) and the specific device (which use springs and counterweight), have been used in daily tasks mainly because of they are less expensive. Comparing these two solutions, it is possible to say that the conventional devices, despite its simplicity and guidance, have limitations when the task requires precision and speed, while the robotic solution has higher complexity in both design and in operation, representing an expensive solution with a programming that restrict the movement. In this context, the present work has the objective the study and development of an intermediate solution between the conventional solution and the robotic device. The proposed study is based on a simplified device, which uses springs and a lever system to handle material. A preliminary study on this mechanism shows imperfections in balance force. In order to correct this error, a control system is used. The control system is constituted by an electric motor, a correcting mechanism, sensors and a controller. The proposed device presents simple control because movements are responsibility of the human operator moreover presents low power consumption, due to the use of springs. A prototype is developed and tests demonstrate the effectiveness of the solution.

Systems that process big data (e.g., high-traffic networks and large-scale storage) prefer data structures and algorithms with small memory and fast processing speed. Efficient and fast algorithms play an essential role in system design, despite the improvement of hardware. This dissertation is organized around a novel algorithm called Othello Hashing. Othello Hashing supports ultra-fast and memory-efficient key-value lookup, and it fits the requirements of the core algorithms of many large-scale systems and big data applications. Using Othello hashing, combined with domain expertise in cloud, computer networks, big data, and bioinformatics, I developed the following applications that resolve several major challenges in the area. Concise: Forwarding Information Base. A Forwarding Information Base is a data structure used by the data plane of a forwarding device to determine the proper forwarding actions for packets. The polymorphic property of Othello Hashing the separation of its query and control functionalities, which is a perfect match to the programmable networks such as Software Defined Networks. Using Othello Hashing, we built a fast and scalable FIB named \textit{Concise}. Extensive evaluation results on three different platforms show that Concise outperforms other FIB designs. SDLB: Cloud Load Balancer. In a cloud network, the layer-4 load balancer servers is a device that acts as a reverse proxy and distributes network or application traffic across a number of servers. We built a software load balancer with Othello Hashing techniques named SDLB. SDLB is able to accomplish two functionalities of the SDLB using one Othello query: to find the designated server for packets of ongoing sessions and to distribute new or session-free packets. MetaOthello: Taxonomic Classification of Metagenomic Sequences. Metagenomic read classification is a critical step in the identification and quantification of microbial species sampled by high-throughput sequencing. Due to the growing popularity of metagenomic data in both basic science and clinical applications, as well as the increasing volume of data being generated, efficient and accurate algorithms are in high demand. We built a system to support efficient classification of taxonomic sequences using its k-mer signatures. SeqOthello: RNA-seq Sequence Search Engine. Advances in the study of functional genomics produced a vast supply of RNA-seq datasets. However, how to quickly query and extract information from sequencing resources remains a challenging problem and has been the bottleneck for the broader dissemination of sequencing efforts. The challenge resides in both the sheer volume of the data and its nature of unstructured representation. Using the Othello Hashing techniques, we built the SeqOthello sequence search engine. SeqOthello is a reference-free, alignment-free, and parameter-free sequence search system that supports arbitrary sequence query against large collections of RNA-seq experiments, which enables large-scale integrative studies using sequence-level data.

A manipulação de materiais é uma das tarefas em que comumente empregam-se robôs para substituir o trabalho humano, dadas algumas vantagens como: maior precisão na manipulação de cargas e maior velocidade de execução da tarefa, bem como por aumentar a segurança do operador. Apesar dessas vantagens, os dispositivos robóticos são largamente empregados apenas em situações em que velocidade e precisão são indispensáveis, em outros casos, os equipamentos convencionais (como talhas, gruas e macacos hidráulicos) e os dispositivos específicos (aqueles fazem uso de molas e contrapesos), vêm sendo utilizados nas tarefas cotidianas, principalmente pelo fato de, entre outros, serem menos dispendiosos. Comparando-se estas duas soluções disponíveis, tem-se que os equipamentos tradicionais, apesar de sua simplicidade e versatilidade de movimentação, apresentam limitações quando são exigidas precisão e eficiência, enquanto os dispositivos robóticos apresentam alta complexidade tanto no projeto quanto na operação, representando uma solução cara e com movimentação restrita pela programação. Neste contexto, o presente trabalho tem por objetivo estudar e propor uma solução intermediária entre a solução convencional e a robótica. O foco do estudo é o projeto de um dispositivo simplificado, que faz uso de molas e de um sistema de alavanca para manipular cargas. Um estudo preliminar desse mecanismo mostrou imperfeições quanto à força de contrabalanceamento. Com o intuito de corrigir esse erro foi usado um sistema de controle, que é constituído por um motor elétrico, um mecanismo de correção, sensores e um módulo controlador. O dispositivo proposto apresenta um controle simplificado, vez que a movimentação é feita exclusivamente pelo operador, possibilitando assim que o dispositivo apresente um baixo consumo de energia. Um protótipo é desenvolvido e os testes demonstraram a eficácia da solução. / The material handling is one task in which robot is commonly employed to replace the human work because it has some advantages such as, higher precision in the handling and higher speed of the task, and to increase operator safety. Despite these advantages, the robotic device is most employed only in situation that speed and precision are essential; in other cases, the conventional equipments (such as hydraulic jacks, cranes and pulley systems) and the specific device (which use springs and counterweight), have been used in daily tasks mainly because of they are less expensive. Comparing these two solutions, it is possible to say that the conventional devices, despite its simplicity and guidance, have limitations when the task requires precision and speed, while the robotic solution has higher complexity in both design and in operation, representing an expensive solution with a programming that restrict the movement. In this context, the present work has the objective the study and development of an intermediate solution between the conventional solution and the robotic device. The proposed study is based on a simplified device, which uses springs and a lever system to handle material. A preliminary study on this mechanism shows imperfections in balance force. In order to correct this error, a control system is used. The control system is constituted by an electric motor, a correcting mechanism, sensors and a controller. The proposed device presents simple control because movements are responsibility of the human operator moreover presents low power consumption, due to the use of springs. A prototype is developed and tests demonstrate the effectiveness of the solution.

Slow rate Denial of Service (DoS) attacks have been shown to be a very effective way of attacking vulnerable servers while using few resources. This thesis investigates the effectiveness of mitigation tools used for protection against slow DoS attacks, specifically slowheader and slow body. Finally, we propose a service that cloud providers could implement to ensure better protection against slow rate DoS attacks. The tools studied in this thesis are, a Web Application firewall, a reverse proxy using an event-based architecture and Amazon’s Elastic Load Balancing. To gather data a realistic HTTP load script was built that simulated load on the server while using probe requests to gather response time data from the server. The script recorded the impact the attacks had for each server configuration.The results show that it’s hard to protect against slow rate DoS attacks while only using firewalls or load balancers. We found that using a reverse proxy with an event-based architecture was the best way to protect against slow rate DoS attacks and that such a service would allow the customer to use their server of choice while also being protected.

Depuis ces années, le développement de systèmes de stockage d'énergie pour la mobilité électrique avec davantage d'autonomie de durabilité est au cœur des contraintes de développement des véhicules électriques ou hybrides entraînant une émergence de l'utilisation des systèmes de management ainsi que des circuits d'équilibrage. Les travaux de thèse portent sur la conception et la réalisation d'une nouvelle structure d'équilibrage à base du réseau de micro-convertisseurs (RµC) utilisant les matrices de connections ainsi que les stratégies de commande appropriées. L'objectif principal est de concevoir un équilibreur actif forcé de haute performance, intégrable à base de technologies d'aujourd'hui et avec une stratégie de contrôle simple à mettre en œuvre. Le mémoire de thèse se structure en quatre chapitres : approche du RµC versus l'équilibrage des batteries, conception de la structure et des stratégies d'équilibrage à base du RµC, conception et dimensionnement du système de contrôle intégrée, version intégrée de l'équilibreur-perspectives. Les premiers prototypes de l'équilibreur utilisant des composants discrets ont été mis en place afin de valider notre structure ainsi que les solutions de contrôle proposées. La réalisation des versions intégrées en se basant sur l'utilisation les technologies disponible au sein du laboratoire ouvre un avenir promettant pour les systèmes de management de batterie. / In recent years, the development of energy storage systems for electric mobility with greater autonomy of sustainability is at the heart of development constraints of electric or hybrid vehicles resulting in the emergence of the use of management systems as well as balancing circuits. The thesis focuses on the design and implementation of a new balancing based network structure of micro-inverters (RμC) using matrices connections and appropriate control strategies. The main objective is to design an active balancer forced high performance integrated based technologies of today and a simple control strategy to implement. The thesis is structured in four chapters: RμC approach versus balancing batteries, structural design and balancing based strategies RμC, design and simulation of control system built, integrated version of the balancer - perspectives. The first prototypes of the balancer using discrete components were developed to validate our structure and control solutions proposed. The realization of integrated based on using the technologies available in the laboratory versions opens a promising future for battery management systems.

The goal of the thesis was to design and create one-way speed controler for brushless DC motors, that is used in air modeling. The function is based on the without sensors control method and circuit is controlled by the Atmel AVR. Power unit for motor is used Li – pol accumulator. The controller is equipped with a BEC to power the receiver and allows monitoring current and voltage on the accumulator. The measured data can be uploaded to a PC.

This thesis deals with the design of a DC/DC converter designed for charging supercapacitors from the 36 V voltage source and consequent back transformation of supercapacitors voltage to the required output voltage. In the thesis the designs of decreasing and increasing DC/DC converters including schematics and calculations of individual components are presented and described. The calculations necessary for the supercapacitors to meet the 10Wh energy condition and the voltage balancer on the capacitors are given below. Completely designed equipment will be assembled and tested on supercapacitors with lower energy.

The goal of the thesis was to design and create one-way speed controler for brushless DC motors, that is used in air modeling. The circuit is controlled by the Atmel AVR. As power unit for motor is used Li–pol accumulator. The controller is equipped with BEC to power the receiver and allows monitoring of current consumption and voltage on the accumulator. Measured data can be upload to a PC where they can be displayed by RegulatorPC in graphical form.