The conditions under which stable separate and coalesced multiple parallel arcs can be operated from a common power supply have been investigated and analysed. Results indicate that any number of stable parallel arcs can be maintained provided each arc is individually stabilised. Multiple electrode configurations relevant to industrial plasma processes have been investigated including coalesced discharges with multiple, individually stabilised, anodes and cathodes and discharges with multiple cathodes and a common anode. The results have been applied to a number of plasma processes including a horizontal multiple discharge system, capable of producing large volumes of ionised gas with a high degree of uniformity, a plasma furnace incorporating multiple de plasma torches operating from a single power supply, and a high-current, non-consumable, multiple cathode assembly for use in do arc furnaces. A horizontal multiple arc system and a plasma furnace incorporating three plasma torches have been designed at the University and are in use for processing material at Cambridge University and in industry respectively.

In present days there is no scientific laboratory without quality, adjustable and powerful source of voltage and current. Therefore this thesis is focused on creating such power source, which can provide voltage and current high enough for most of experiments or for development electrical devices or parts, which are not connected to power grid. This power source is able to provide symmetric voltage 30 V and current 6 A high in each branch. It is possible to control this power source remotely thanks for USB interface, which is standard equipment of majority of modern devices in these days. LCD display is part of this source, which shows the user set and real parameters at the output as well.

Apresentam-se modelos matemáticos de poucos graus de liberdade para o estudo de vibrações estruturais não lineares excitadas por fonte não-ideal de energia, amortecidas por impacto, para duas aplicações: um pórtico que serve de apoio para um motor elétrico e uma torre de suporte a uma turbina eólica. Considera-se a existência de interação entre o fornecimento de energia e o movimento da estrutura de suporte. Se a potência fornecida pela fonte de energia não é suficiente, a rotação do rotor pode ficar estagnada à freqüência de ressonância da estrutura, impossibilitando o mesmo de alcançar regimes de rotação mais altos. Isso é uma manifestação do chamado Efeito Sommerfeld. No primeiro modelo, somente dois graus de liberdade são considerados: o movimento horizontal da estrutura, na direção perpendicular ao eixo do rotor, e a rotação do rotor. Depois, adiciona-se outro grau de liberdade, representando o movimento de uma pequena massa que se desloca livremente dentro de uma câmara (amortecedor por impacto). As equações de movimento desses modelos são obtidas via formulação Lagrangiana. Por intermédio de simulações numéricas, procurou-se estudar os parâmetros do amortecedor por impacto que produzem a melhor eficiência do dispositivo. Nota-se que o impacto da massa com as paredes do recipiente fornece controle da amplitude de vibração da estrutura e da largura da banda de freqüências em que o Efeito Sommerfeld ocorre. / We present mathematical models with few degrees of freedom for the study of nonlinear structural vibrations excited by a non ideal energy source, with impact damping, for two applications: a portal frame that supports an electric motor and a tower structure supporting an aeolian turbine. We consider that there is interaction between the energy supply and the motion of the supporting structure. If the power supplied by the energy source is not enough, the rotation of the engine may get stuck at a resonance frequency of the structure, disabling the engine to reach higher regimes of rotation. This is a manifestation of the so-called Sommerfeld Effect. In the first model, only two degrees of freedom are considered: the horizontal motion of the structure, in the transverse direction to the axis of the rotor, and the rotation of the rotor. Next, another degree of freedom is added to the model, representing the motion of a rolling small mass, free to bounce back and forth inside a chamber (impact damper). The equations of motion of these models are obtained via a Lagrangian approach. The parameters that produce the greatest effectiveness of the impact damper were studied through numerical simulations. One notices that the impact of the mass with the walls of the container supplies control of the vibration amplitude of the structure and the width of the band of frequencies where the Sommerfeld Effect occurs.

Apresentam-se modelos matemáticos de poucos graus de liberdade para o estudo de vibrações estruturais não lineares excitadas por fonte não-ideal de energia, amortecidas por impacto, para duas aplicações: um pórtico que serve de apoio para um motor elétrico e uma torre de suporte a uma turbina eólica. Considera-se a existência de interação entre o fornecimento de energia e o movimento da estrutura de suporte. Se a potência fornecida pela fonte de energia não é suficiente, a rotação do rotor pode ficar estagnada à freqüência de ressonância da estrutura, impossibilitando o mesmo de alcançar regimes de rotação mais altos. Isso é uma manifestação do chamado Efeito Sommerfeld. No primeiro modelo, somente dois graus de liberdade são considerados: o movimento horizontal da estrutura, na direção perpendicular ao eixo do rotor, e a rotação do rotor. Depois, adiciona-se outro grau de liberdade, representando o movimento de uma pequena massa que se desloca livremente dentro de uma câmara (amortecedor por impacto). As equações de movimento desses modelos são obtidas via formulação Lagrangiana. Por intermédio de simulações numéricas, procurou-se estudar os parâmetros do amortecedor por impacto que produzem a melhor eficiência do dispositivo. Nota-se que o impacto da massa com as paredes do recipiente fornece controle da amplitude de vibração da estrutura e da largura da banda de freqüências em que o Efeito Sommerfeld ocorre. / We present mathematical models with few degrees of freedom for the study of nonlinear structural vibrations excited by a non ideal energy source, with impact damping, for two applications: a portal frame that supports an electric motor and a tower structure supporting an aeolian turbine. We consider that there is interaction between the energy supply and the motion of the supporting structure. If the power supplied by the energy source is not enough, the rotation of the engine may get stuck at a resonance frequency of the structure, disabling the engine to reach higher regimes of rotation. This is a manifestation of the so-called Sommerfeld Effect. In the first model, only two degrees of freedom are considered: the horizontal motion of the structure, in the transverse direction to the axis of the rotor, and the rotation of the rotor. Next, another degree of freedom is added to the model, representing the motion of a rolling small mass, free to bounce back and forth inside a chamber (impact damper). The equations of motion of these models are obtained via a Lagrangian approach. The parameters that produce the greatest effectiveness of the impact damper were studied through numerical simulations. One notices that the impact of the mass with the walls of the container supplies control of the vibration amplitude of the structure and the width of the band of frequencies where the Sommerfeld Effect occurs.

Subject of this master’s thesis is ideological proposal of the UPS able to protect electronic equipment against short-term disruptions of network supply voltage. The entire facility is proposed on the basis of modern switching technologies . Properties of critical parts of the proposal are simulated and debugged with help of PSpice circuit simulator software. In project is also included the necessary design documents. The project is completed by realization of functional facility, measurement of it’s basic properties and comparison with assumption results.

The triboelectric nanogenerator (TENG) has attracted global attention in the fields of power sources and self-powered sensors. By coupling the omnipresent triboelectrification effect and the electrical induction effect, the TENGs can transduce ambient mechanical energy into electrical energy. Such energy could be consumed instantaneously or stored for later use. In this way, they could be deployed distributedly to be compatible power sources in the era of the internet of things (IoTs), completing the powering structure that is currently relying on power plants. Also, the electrical signals can reflect the environment changes around the TENGs. Thus, the TENGs can serve as self-powered sensors in the IoTs. In this work, we adopted two approaches for TENG fabrication: the thermal drawing method (TDP) and 3D printing. With TDP, we have fabricated scalable fiber-based triboelectric nanogenerators (FTENG), which have been woven into textiles by an industrial loom for wearable use. This fabrication process can supply FTENG on a large scale and fast speed, bridging the gap between the TENG and weaving industry. With 3D printing, we have fabricated TENGs that are compatible with the shape of arbitrary substrates. They have been used as biocompatible sensors: human-skin-compatible TENG has been used to recognize silent speech in real-time by sensing the chin movement; the porcine-kidney-shaped fiber mesh has been used to monitor the perfusion rate of the organ. These works have extended the territory of TENGs and can be critical components in the IoTs. / Ph.D. / Portable electronic devices have become important components in our daily lives, and we are entering the era of the Internet of Things (IoTs), where everyday objects can be interconnected by the internet. While electricity is essential to all of these devices, the traditional power sources are commonly heavy and bulky and need to be recharged or directly connected to the immobile power plants. Researchers have been working to address this mismatch between the device and power systems. The triboelectric nanogenerators (TENG) are good candidates because they can harvest energy in the ambient environment. The users can use them to generate electricity by merely making the rubbing motion. In this work, we report two fabrication methods of the fiber-based triboelectric nanogenerators (FTENG). With the thermal drawing process, we have fabricated sub-kilometer-long FTENG and wove it with the regular cotton yarn into textiles. The wearable power source is human friendly as it does not induce any extra weight load for the user. Besides, we have demonstrated that such long fibers can work as self-powered distributed sensors, such as a Morse code generator. With 3D printing, we have fabricated FTENG-based devices that conform to the working substrates, which can be any shape. We have employed them as biofriendly sensors to translate the chin movement during speaking to language and to monitor the perfusion rate of a pig kidney. The FTENGs have offered excellent comfortability to the users and can play a vital role in reframing the power structure to be compatible with IoTs.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this thesis an study of AC Power Source (ACPS) topologies that guarantee the synthesis of high quality voltage waveforms (in comparison to the reference signal) without penalizing the system efficiency is carried out. It must be highlighted that these features can be achieved by employing hybrid topologies, which are composed of a switched-mode power amplifier and a linear power amplifier (LPA). The former amplifier (called main amplifier) processes almost the entire load power, while the second one (called correction amplifier) is responsible for the compensation for any distortion at the output voltage waveform, thus, processing a small amount of the load power. In this way, it is possible to combine both the high efficiency of switched-mode power amplifiers with high quality voltage waveforms characteristic of linear power amplifiers. This work is mainly focused on hybrid topologies in series configuration (series connection between main and correction amplifiers). This allows to employ a low voltage/low power LPA. It must be noticed that this configuration is especially suitable for ACPS applications, when, for example, the mains voltage is intended to be emulated (including high order harmonics, controlled disturbances, etc.), since the LPA experiences low voltage levels in comparison to those synthesized by the ACPS. Throughout the thesis are proposed and theoretically/ experimentally analyzed two novel ACPS topologies, which employ multilevel inverters as main amplifier. The analysis take into account the operation, modulation strategy and design methodology of the power and control circuits (of both main and correction amplifiers). Experimental results are presented (Total Harmonic Distortion and converter efficiency) in order to validate the proposed approach. / Nesta Tese é realizado um estudo acerca das principais topologias de fontes CA de potência (AC Power Source ACPS), que garantem a síntese de formas de onda de tensão de alta fidelidade (com respeito ao sinal de referência) sem, no entanto, comprometer o rendimento do sistema. Salienta-se que essas características podem ser obtidas por topologias híbridas, compostas pela associação de um amplificador chaveado com um amplificador linear. Enquanto o primeiro (denominado de amplificador principal) processa praticamente a totalidade da energia fornecida à carga, o segundo (denominado de amplificador de correção) é responsável apenas por correções na forma de onda de saída, processando, assim, uma pequena parcela de energia. Então, torna-se possível aliar o alto rendimento característico dos conversores chaveados à alta qualidade da forma de onda associada aos amplificadores lineares. O trabalho é direcionado, principalmente, a topologias híbridas em configuração série (conexão série entre o amplificador principal e o amplificador de correção), de modo que amplificadores de correção de baixa tensão/baixa potência possam ser empregados. Destaca-se que essa configuração é especialmente adequada a aplicações com ACPSs, quando, por exemplo, deseja-se emular a rede elétrica de alimentação (inserindo harmônicos de tensão, provocando distúrbios controlados, etc.), uma vez que o amplificador de correção é submetido a níveis de tensão reduzidos, se comparados aos níveis sintetizados pela ACPS. No decorrer do trabalho, são propostas e analisadas teórico-experimentalmente duas topologias inéditas de ACPS, ambas empregando inversores multiníveis como amplificador principal. São apresentadas análises relativas à operação, modulação, metodologia de projeto dos estágios de potência e controle tanto do amplificador principal quanto do de correção , bem como são apresentados resultados experimentais em termos da distorção harmônica total (Total Harmonic Distortion THD) e rendimento global do sistema.

This work deals with the design and realization of a modular security central unit's hardware positioned in familial houses. As an operating component of the central unit is used Module Rabbit 3365 with an integrated Ethernet interface. Based on user's requirements and general requirements for electronic security system, circuit diagrams of the central unit's motherboard and power supply with a function of backup power supply are designed. The work also includes layout of a keyboard and LCD display. Printed circuit boards are designed, produced and assembled. The device is set to work. The last part concerns programming of the module Rabbit 3365 in Dynamic C. Gradually, set of operating functions for individual components of the security central unit are implemented.

This diploma thesis discusses the issue of finding type of water turbine for very low heads and low discharges, which could be operated as mobile micro hydropower plant in island mode. Thesis deals with summary of appropriate choices of water turbine for needs of micro hydropower plant. Essential part of diploma thesis deals with design of optimized waterwheel. Waterwheel was chosen because commercial high-speed turbines have low efficiency for low heads. Waterwheel was manufactured and measured in laboratories of Fluid engineering. Measurement output was discharge and efficiency characteristic of turbine. The price calculation was made after manufacture.

行銷通路經過幾年來的變革已成為產業成功的一項關鍵。誰能掌握通路，誰就能掌握產業的命脈。因此國內廠商紛紛投入通路的經營，如統一企業創立統一超商，泰山企業設立福客多超商，味全的安賓及康國行銷等，莫不以掌握通路為要務。而萬客隆量販店的設立更是對傳統通路造成極大的衝擊，亦更顯現出通路的重要性。 　　飲料業的產品特性為產品生命週期短、週轉快，先期進入往往成為領導品牌、通路是成功關鍵及流行跟隨日本腳步等。由於飲料業的這些特性，可知通路是飲料成功的命脈。往往誰有良好的通路，誰就能脫穎而出，成為優秀的製造商。故如何維持與通路良好的關係，實是飲料業界應重視的課題。 　　本論文主要研究的主題在探討通路間製造商權力、權力來源及經銷商對製造商之依賴與經銷商抗衡權與通路衝突間之關係。以了解通路間之關係並進而提出相關建議供業界參考。 　　本文重要之研究結果約如下述： 　　1.就製造商權力來源與通路衝突言，大製造商通常採用非強制權力來源，因而與經銷商的衝突會較少。反之，小製造商則採用強制權力來源則會增加通路間之衝突。故建議，若在資源許可的情況下，小製造商應盡量少運用強制權力以減少通路間的衝突，以使與經銷商間的關係衝突減少，關係更為良好。 　　2.就製造商權力與通路衝突之研究，大製造商在此向關係上不顯著，小製造商則達顯著水準。顯示出小製造商運用其權力時，易招致經銷商的負面反應，而導致通路關係之不良。故小製造商在運用其權力時，應多加考慮經銷商可能之反應，以免破壞彼此之關係。 　　3.就製造商權力與經銷商對製造商依賴言，經銷商對大製造商有較高之依賴。而對小製造商則關係不顯著。而相對應於通路衝突來分析，可發現經銷商對製造商依賴大的話，製造商應用影響力較不致引起經銷商的反抗。故對小製造商而言，如何結合有限的資源，以使經銷商能更加的依賴製造商是值得探討的關鍵所在。 　　4.在經銷商抗衡權與通路衝突方面，由研究可發現，無論大小製造商，經銷商的抗衡權都會導致通路衝突的增加。此意味製造商對於經銷商本身所具備的各項資源與條件應做適當的評估，在制定通路決策時，應考慮到經銷商抗衡能力的大小，則決策方可有效的推行。