Made available in DSpace on 2015-05-08T14:59:58Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 18446929 bytes, checksum: 4766e609aa9084be93f441b28db115b6 (MD5) Previous issue date: 2014-10-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The three phase induction motor (MIT) is the main system in electromechanical conversion, present in practically all industrial processes. Due to its versatility and low cost, the use of frequency inverters combined with MIT practically replaced the DC motors in systems requiring variation in angular velocity. For closed-loop control at MIT, without the use of speed sensors (sensorless), it is essential to estimate the velocity on the axis with high accuracy and with satisfactory response time. The proposed work has the object of analyzing different methods that can be employed to estimate the speed in sensorless axis, named according to their fundamental principle, they are: the method of harmonic slots, the torque in the air gap and the acoustic emission. The first mentioned is the best known non-invasive method in the state art, the second one was recently developed in the laboratory and the third one was exhibited here for the first time. All methods are compared with a reference instrument for measuring speed (tachometer). In order to obtain validation of the techniques we constructed a work bench tests basically composed by a three phase induction motor, torque meter and DC motor used as a generator (to enforce the axis load variable). The main objective of the study is to compare the methods for various situations of speed and load, also based on the degree of invasiveness and accuracy of each method. For the development and analysis of technique for harmonic slots and acoustic emission, a spectral analysis by Fourier transform of the current signal and the sound was performed, respectively. It was used tools such as MATLAB and LABVIEW for the computational study. After extensive experimental testing, the methods have been validated and it was obtained conclusions about different aspects of each discussed technique. / O motor de indução trifásico (MIT) é o principal sistema de conversão eletromecânica existente, presente em praticamente todos os processos industriais. Devido a sua versatilidade e razoável baixo custo, a utilização de inversores de frequência combinados com os MIT, praticamente, substituíram os motores de corrente contínua em sistemas que necessitam de variação de velocidade angular. Para o controle de malha fechada em MIT, sem a utilização de sensores de velocidade (sensorless), é fundamental que se estime a velocidade no eixo com alta exatidão e com tempo de resposta satisfatório. O trabalho proposto visa analisar diferentes métodos que podem ser empregados para estimação na velocidade no eixo sensorless, denominados de acordo com o seu princípio fundamental, são eles: método pela harmônicas das ranhuras, pelo torque no entreferro e pela emissão acústica. Sendo o primeiro citado, o método não-invasivo mais conhecido no estado arte, o segundo, desenvolvido recentemente em laboratório e o terceiro, exposto aqui pela primeira vez. Todos os métodos são comparados com um instrumento de referência para medida de velocidade (tacômetro). A fim de se obter a validação das técnicas empregadas foi construída uma bancada de testes experimentais composta basicamente por um motor de indução trifásico, torquímetro e motor de corrente contínua utilizado como gerador (para impor carga variável ao eixo). O principal objetivo do estudo é comparar os métodos para diversas situações de velocidade e carga, tendo também como base o grau de invasividade e exatidão de cada método. Para o desenvolvimento e análise da técnica pela harmônicas das ranhuras e da emissão acústica, foi realizada uma análise espectral pela Transformada de Fourier do sinal da corrente e do som, respectivamente. Usou-se para este estudo ferramentas computacionais como o LABVIEW e MATLAB. Depois de extensos ensaios experimentais, os métodos foram validados e obteve-se conclusões sobre diferentes aspectos de cada técnica analisada.

A fresh perspective on covert channels is presented in this work. A new class, air-gap covert channels, is defined as an unintentional communication channel established between systems that are physically and electronically isolated from one another. A specific class of air-gap covert channel is studied in depth, out-of-band covert channels (OOB-CCs), which are defined as policy-breaking communication channels established between isolated, physically unmodified systems. It is shown that OOB-CCs can be categorized by the physical channel that they communicate over: acoustic, light, seismic, magnetic, thermal, and radio-frequency, and the hardware that is required at the transmitter and receiver to make covert communication possible. In general, OOB-CCs are not as high-bandwidth as conventional radio-frequency channels; however, they are capable of leaking sensitive information that requires low data rates to communicate (e.g., text, recorded audio, cryptographic key material). The ability for malware to communicate information using a specific type of OOB-CC, the covert-acoustic channel, is also analyzed. It is empirically demonstrated that using physically unmodified, commodity systems (e.g., laptops, desktops, and mobile devices), covert-acoustic channels can be used to communicate at data rates of hundreds of bits per second, without being detected by humans in the environment, and data rates of thousands of bits per second when nobody is around to hear the communication. Defence mechanisms to counter covert-acoustic channels are also proposed and evaluated, and, as a result, best practices for the designers of secure systems and secure facilities are presented. Additionally, the covertness of OOB-CCs, i.e., the amount of data that can be leaked before the channel is detected, is also determined for classical communication channels as well as for covert-acoustic channels.

This project deals with simulation´s possibilities of air flow in electric machines. A finite element method is the final element technique. Aim of this project is conversion universal formula for calculation friction dissipation factor. For its location is necessary to create 27 simulations according to the 2. plan order. Usage programme MATLAB for processing results obtain requisite algorithm for calculation friction dissipation factor.

Táto práca sa zaoberá s modelovaním synchronného stroja s permanentnými magnetmi pomocou metody konečných prvkov. K modelovaniu sme si zvolili 3 fázový synchronný stroj s permanentnými magnetmi na povrchu rotora z firmy VUES. Najprv vypočítame parametre stroja a potom spravíme statický model pomocou programu FEMM a Matlab a budeme hladať možné riešenia na 2D dynamický model. Pomocou programu Ansys Workbench spravíme 3D model tohoto stroja budeme a porovnávať výsledky simulácie.

The thesis focuses on constructing dynamic model - synchronous generator with using magnetic equivalent circuit diagrams. The model construction is based on knowledge of geometric parameters, magnetic characteristic of used material and fyzical deployment of vindings placed in stator slots. Computed reults are compared with results optained from model created with finite element method.

The main goal of this thesis is a determination of an idle stray losses in induction machine and creation calculation program in MATLAB. The stray losses are caused especially by the eddy currents on the surface of stator and rotor, further by a pulsation of these currents owing to the periodical change of air-gap permeance, magnetic induction in stator and rotor teeth and a differential leakage. Value of stray losses are different of engine construction especially by it are scoring insulated, uninsulated, straight or slant.

In der vorliegenden Arbeit wird ein neues Verfahren zur Dünnschichtverkappung von oberflächennahen Mikrostrukturen vorgestellt. Ausgehend von den speziellen Anforderungen an die Verkappung oberflächennaher Mikrostrukturen, insbesondere von Strukturen mit hohem Aspektverhältnis, wurden die Verwendung eines Fluor-Kohlenstoff-Polymers als Opferschichtmaterial und die Eignung unterschiedlicher Schichtstapel zur Realisierung der Dünnschichtkappe untersucht. Die resultierende Technologie ermöglicht eine durchgehend trockenchemische Prozessierung. Für die Abschätzung der notwendigen Schichtdicken und den geometrischen Entwurf der Kappenstrukturen, wurden auf Basis der Plattentheorie analytische und numerische Modelle erstellt. Verschiedene Materialkombinationen bestehend aus Siliziumoxid, Siliziumnitrid und Aluminium wurden hinsichtlich ihrer mechanischen und thermomechanischen Eigenschaften untersucht und bewertet. Ein weiterer Schwerpunkt lag auf der Entwicklung und Optimierung der Opferschichtprozesse, sowie deren Integration in die Gesamttechnologie. Die Eignung der plasmagestützten Prozesse zur Abscheidung und Strukturierung des Opferpolymers wurde durch die Fertigung von verkapselten Beschleunigungssensoren nachgewiesen. Ein ausreichender hermetischer Verschluss der Dünnschichtkappe konnte durch die Messung der viskosen Dämpfung an Feder-Masse-Schwingern bestätigt werden.

Permanent magnet (PM) machines offer several advantages in traction applications such as high efficiencyand high torque per volume ratio. The iron losses in these machines are estimated mostly with empiricallaws taken from other types of machines or with finite element simulations (FEM). In the first part of thisthesis the objective is to define an accurate analytical model for the stator yoke, teeth and rotor of a PMmotor which should work well enough for all operating point (different loads and frequency).This analytical model is found using an iterative process. After building a loss matrix and flux matrix basedon FEM simulations, it is possible to curve fit each of the lines or the rows of the matrix in order to achievethe best fitting for every operating point. This is a very new approach; it was shown that it gives thepossibility, even with a very limited number of FEM simulations, to achieve an accurate estimation of thelosses.The second part of this report focuses on optimizing this analytical method, comparing it with otherpossibilities, analyzing limits and advantages. Special attention is also given to the effects of the losses onthe temperatures in different parts of the machine. In the last part of the thesis, the analytical model isused to test a new control strategy. Its goal is to reduce the total losses of the motor and optimize the ratiobetween torque and total losses for a given driving cycle.

Water purification systems have made access to drinking water easier by treating water sources which previously could not be used for drinking. Such systems however require energy and materials to build and operate which means they have environmental impacts. This thesis performs a cradle to grave life cycle assessment of a solar driven HVR water purification system used to treat contaminated groundwater in Odisha, India. The system has three subsystems each with different components – a water purification subsystem that uses an air gap membrane distillation (AGMD) process to purify ground water to produce drinking water, a solar photovoltaic subsystem to provide electricity and a solar thermal subsystem with evacuated tube collectors to provide hot water. The timeframe of the study is 15 years and the chosen functional unit is 590 m3 of drinking water produced over 15 years. The environmental impacts of the system are evaluated using the ReCiPe Midpoint (H) impact assessment method and the life cycle is modelled in the software SimaPro using the Ecoinvent database for inventory data. A comparison is then made between the lifecycle impact of a solar driven HVR water purification system and a grid driven HVR system as well as a water purification system with conventional end of life treatment and a system with state of the art end of life treatment. Along with the lifecycle impact, the levelized cost of water of the water purification system has also been calculated. The results show that within the entire system the solar PV subsystem has the highest impact due to the high electricity consumption during silicon purification for manufacturing the solar panels. The solar thermal subsystem has the next highest impact with the biggest contributor being the manufacturing of glass tubes for the solar collectors. The water purification subsystem has the least impact with the highest share due to use of acetic acid during its use phase for maintenance. The modelling results focus on four impact categories and show the following life cycle impacts - global warming potential : 27 180 kg CO2eq, human carcinogenic toxicity : 2 412 kg 1.4-DCB eq, marine ecotoxicity : 2 662 kg 1.4-DCB eq, freshwater ecotoxicity : 1 967 kg 1.4-DCB eq. The grid operated system shows a lifecycle impact 70 to 170 times higher across these four impact categories compared to the solar driven system. This is due to the high share of fossil fuels in the Indian electricity grid. The state-of-the-art end of life treatment shows a 17% and 22% reduction in freshwater as well as marine ecotoxicity impacts of the system compared to conventional end of life treatment with negligible impacts on global warming and human carcinogenic toxicity. The levelized cost of water calculations show that the system with its current runtime of 6 hours when run using solar energy or the grid is not economically competitive compared to bottled water in India. A sensitivity analysis is then performed to evaluate the sensitivity of lifecycle impact to maintenance frequency and the lifetime of components and the sensitivity of the levelized cost of water to discount rate and the production cost of AGMD modules. The analysis shows that only the lifetime of components has a significant influence on the life cycle impactof the system, the maintenance frequency has a significant impact on freshwater and marine ecotoxicitywhile the discount rate and production cost of AGDM modules has no impact on the levelized cost of water. In conclusion the findings of this thesis agree with the major findings of previous studies done on the topic and adds to the limited knowledge in the literature on the life cycle impact of solar powered AGMD systems. / Vattenreningssystem har gjort förenklat tillgången till dricksvatten genom att behandla vattenkällor som tidigare inte gick att komma åt för att dricka. Sådana system kräver dock energi och material för att bygga och fungera, vilket innebär att de kommer med en miljöbelastning. Detta examensarbete utför en livscykelanalys från vagga till grav av ett vattenreningssystem som används för att behandla förorenat grundvatten i Odisha, Indien. Systemet renar grundvatten genom en destillationsprocess för luftgapmembran och möter sitt elbehov med hjälp av ett solcells-PV-delsystem och varmvattenbehov genom ett solvärmedelsystem med evakuerade rörkollektorer. Den valda funktionsenheten är 590 m3 dricksvatten producerat över 15 år. Systemets miljöpåverkan utvärderas med hjälp av konsekvensbedömningsmetoden ReCiPe Midpoint (H) och livscykeln modelleras i programvaran SimaPro med hjälp av Ecoinvents databas. En jämförelse görs sedan mellan miljöpåverkan från ett solcellsdrivet och ett elnätsdrivet vattenreningssystem och en mellan ett vattenreningssystem med konventionell samttoppmodern avfallshantering. Tillsammans med miljöpåverkan har även den utjämnade kostnaden (LCOW) för vatten i vattenreningssystemet beräknats. Resultaten visar att solcellsdelsystemet har störst miljöpåverkan på grund av den höga elförbrukningen under kiselrening för tillverkning av solpanelerna. Solvärmedelsystemet har den näst högsta påverkan med näst högsta andelen på grund av tillverkningen av glasrör för solfångarna. Delsystemet för vattenrening har minst påverkan varav den högsta andelen kommer från användningen för underhåll av systemet under operationella fas. Modelleringsresultaten fokuserar på fyra påverkanskategorier och visar följande potentiell miljöpåverkan - global uppvärmningspotential: 27 180 kg CO2ekv, mänsklig cancerogen toxicitet: 2 412 kg 1,4-DCB ekv, marin ekotoxicitet: 2 662 kg 1,4-DCB ekv, sötvattensekotoxicitet: 1 967 kg 1,4-DCB ekv. Det nätdrivna systemet visar 70 till 170 g[nger högre stor miljöpåverkan jämfört med det solcellsdrivna systemet i de fyra påverkanskategorierna på grund av den höga andelen fossila bränslen i det indiska elnätet. Medtoppmodern avfallshantering minskat systemets akvatiska och marina ekotoxicitetseffekter med en 10 % jämfört med konventionell avfallshantering och med försumbar påverkan på global uppvärmning och mänsklig cancerogen toxicitet. Den utjämnade kostnaden för vatten visar att när systemet med sin nuvarande drifttid på 6 timmar per dag varken kopplad till solenergi eller elnätet är ekonomiskt konkurrenskraftigt jämfört med vatten på flaska i Indien. En känslighetsanalys utförs sedan på fyra parametrar - underhållsfrekvens, komponenters livslängd, diskonteringsränta och kostnaden för destillationsmodulerna för luftgapmembran för att se deras inverkan på systemets miljöpåverkan och utjämnade vattenkostnader. Analysen visar att endast komponenternas livslängd har en betydande inverkan på systemets livscykelpåverkan, underhållsfrekvensen har en betydande inverkan på sötvatten och marin ekotoxicitet medan diskonteringsräntan och produktionskostnaden för AGDM-moduler inte har någon inverkan på den utjämnade kostnaden för vatten. Sammanfattningsvis kommer resultaten av denna studie att lägga till den begränsade kunskapen i litteraturen om livscykelpåverkan av soldrivna luftgapmembrandestillationssystem.

L’alternateur étudié dans cette thèse équipe une éolienne flottante à axe vertical. Il s’agit d’unemachine synchrone de 2MW, polyphasée, bobinée sur plots, à pas fractionnaire, à aimants et à prisedirecte. L’objectif majeur de la thèse est la caractérisation de cet alternateur afin d’en évaluer lesperformances. Une modélisation analytique de la perméance d'entrefer et de la force magnétomotriceont conduit à l'étude de l'induction d'entrefer dont le contenu harmonique s'est révélé êtreparticulièrement riche. La caractérisation a également porté sur la détermination des inductancespropres et mutuelles, avec un calage du modèle effectué en exploitant des mesures expérimentalesfaites à l’arrêt. La particularité de la machine étudiée nous a amené à considérer un enroulement fictiféquivalent dans le but de déterminer les inductances cycliques, nécessaires à l'établissement du schémamonophasé équivalent. De plus, le fonctionnement back to back de la machine a été étudié et simulé. Ilpermet de faire des tests de la machine elle-même mais aussi des éléments de la chaîne de conversion,sans l'utilisation d'une deuxième machine ou des pâles pour entraîner le rotor du prototype. Il offre enplus la possibilité de tester différents type de fonctionnements et d'évaluer la puissance que peutproduire la machine : différents scénario de fonctionnement ont été simulés et les paramètresnécessaires aux essais sur site ont été définis. Le fonctionnement back to back a fait l’objetd’investigation sur une machine synchrone classique. Les difficultés de fonctionnement ontnotamment pu être mises en évidence avec une modélisation analytique des phénomènesélectromagnétique qui s'y produisent et des essais expérimentaux. / The studied alternator equips a vertical axis offshore wind turbine. It is a 2MW fractional slotconcentrated winding permanent magnet synchronous polyphase machine, directly connected to bladeturbine. The principal purpose of this thesis consists in characterizing the alternator in order toevaluate its performances. The air gap permeance and the magnemotive force analytical modelingleads to study the air gap flux density and its harmonic content, which is particularly rich. Thecharacterization has also concerned the self and mutual inductance determination, which has requiredstalling the model by exploiting experimental measurements done at standstill. The particularity of thestudied machine leads us to consider an equivalent fictitious winding in order to determine the cyclicalinductances, necessary for the single-phase equivalent scheme establishment. Moreover, the machineback to back functioning has been studied and simulated. This functioning allows testing the machineitself and the other conversion chain subsystems, without using a second machine or blades to drivethe prototype rotor. It offers the possibility to test different types of operating points and to estimatethe power that can produce the studied machine: different operating points scenarios have beensimulated and parameters for tests have been defined. The back to back functioning of a classicalsynchronous machine has been also investigated, with an analytical modeling of the electromagneticphenomena and experimental tests.