Development and characterization of cutting-edge equipment for EMC measurements and advanced power line filter design

This Doctoral Thesis aims at studying, developing, and characterizing cutting edge equipment for EMC measurements and proposing innovative and advanced power line filter design techniques. This document summarizes a three-year work, is strictly industry oriented and relies on EMC standards and regulations. It contains the main results, findings, and effort with the purpose of bringing innovative contributions at the scientific community. Conducted emissions interferences are usually suppressed with power line filters. These filters are composed by common mode chokes, X capacitors and Y capacitors in order to mitigate both the differential mode and common mode noise, which compose the overall conducted emissions. However, even at present days, available power line filter design techniques show several disadvantages. First of all, filters are designed to be implemented in ideal 50 Ω systems, condition which is far away from reality. Then, the attenuation introduced by the filter for common or differential mode noise is analyzed independently, without considering the possible mode conversion that can be produced by impedance mismatches, or asymmetries in either the power line filter itself or the equipment under test. Ultimately, the instrumentation used to perform conducted emissions measurement is, in most cases, not adequate. All these factors lead to an inaccurate design, contributing at increasing the size of the filter, making it more expensive and less performant than it should be.

Application of active and transfer learning to wound image segmentation

Wound management is a fundamental task in standard clinical practice. Automated solutions already exist for humans, but there is a lack of applications on wound management for pets. The importance of a precise and efficient wound assessment is helpful to improve diagnosis and to increase the effectiveness of treatment plans for the chronic wounds. The goal of the research was to propose an automated pipeline capable of segmenting natural light-reflected wound images of animals. Two datasets composed by light-reflected images were used in this work: Deepskin dataset, 1564 human wound images obtained during routine dermatological exams, with 145 manual annotated images; Petwound dataset, a set of 290 wound photos of dogs and cats with 0 annotated images. Two implementations of U-Net Convolutioal Neural Network model were proposed for the automated segmentation. Active Semi-Supervised Learning techniques were applied for human-wound images to perform segmentation from 10% of annotated images. Then the same models were trained, via Transfer Learning, adopting an Active Semi- upervised Learning to unlabelled animal-wound images. The combination of the two training strategies proved their effectiveness in generating large amounts of annotated samples (94% of Deepskin, 80% of PetWound) with the minimal human intervention. The correctness of automated segmentation were evaluated by clinical experts at each round of training thus we can assert that the results obtained in this thesis stands as a reliable solution to perform a correct wound image segmentation. The use of Transfer Learning and Active Semi-Supervied Learning allows to minimize labelling effort from clinicians, even requiring no starting manual annotation at all. Moreover the performances of the model with limited number of parameters suggest the implementation of smartphone-based application to this topic, helping the future standardization of light-reflected images as acknowledge medical images.

Grid Integration of Offshore Wind Farms Using Modular Marx Multilevel Converters

This paper proposes the use of a Modular Marx Multilevel Converter, as a solution for energy integration between an offshore Wind Farm and the power grid network. The Marx modular multilevel converter is based on the Marx generator, and solves two typical problems in this type of multilevel topologies: modularity and dc capacitor voltage balancing. This paper details the strategy for dc capacitor voltage equalization. The dynamic models of the converter and power grid are presented in order to design the converter ac output voltages and the dc capacitor voltage controller. The average current control is presented and used for power flow control, harmonics and reactive power compensation. Simulation results are presented in order to show the effectiveness of the proposed (MC)-C-3 topology.

Loistehon tuottaminen painehiomon tahtimoottoreilla

Tämän työn tavoitteena on selvittää, millaisia häviöitä loistehon tuottaminen Stora Enson Anjalankosken tehtaiden hiomorakennuksessa sijaitsevilla kuudella 14 MW tahtimoottorilla aiheuttaa. Lähtötietoina käytettiin moottoreiden valmistajalta saatuja rkistotietoja ja niiden perusteella laadittiin äivitetty akselitehon ja loistehotuotannon ilaa kuvaava PQ-diagrammi digitaaliseen muotoon. Saatujen tulosten avulla on mahdollista suunnitella kustannustehokas tapa käyttää painehiomon tahtimoottoreita koko tehdasalueen loistehon säätöön.

20 kV ilmajohtoverkon maakaapeloinnin vaikutus maasulkusuojaukseen ja loistehotaseeseen

Sähkömarkkinalakimuutokset ovat ohjanneet useita verkkoyhtiötä muuttamaan investoin-tistrategioitaan. Kiristyneet toimitusvarmuusvaatimukset edellyttävät useilta verkkoyh-tiöiltä aiempaa suurempaa panostusta jakeluverkon kehittämiseksi. Toimitusvarmuusvaa-timusten täyttäminen edellyttää myös merkittäviä muutoksia verkkoyhtiöiden käyttämiin verkostotekniikoihin. Suurhäiriöille alttiita ilmajohtoja muutetaan verkkoyhtiöissä totuttua nopeammalla aikataululla maakaapeleiksi tiukentuneiden toimitusvarmuusvaatimusten täyttämiseksi. PKS Sähkönsiirto Oy:n 20 kV sähköverkko on ollut suurimmalta osalta avojohtoverkkoa jossa toimitusvarmuus ei ole nykyisellään muuttuneen sähkömarkkinalain asettamalla ta-solla. Tämä on johtanut verkostostrategian luomiseen, jossa yhtenä toimena toimitusvar-muuden lisäämiseksi vaaditulle tasolle on avojohtolinjojen korvaaminen maakaapeleilla. Maakaapelointien nopea rakennusaikataulu tuo monia haasteita verkkoyhtiöille. Maakaa-pelointien korkea maasulkuvirran ja loistehon tuotto verrattuna avojohtoverkkoon tulee huomioida yhtiössä verkkoa rakennettaessa. Tässä diplomityössä selvitetään PKS Sähkönsiirto Oy:n verkostostrategian mukaisten maakaapelointien vaikutuksia sähköverkolle. Työssä on arvioitu tavoiteverkon mukaisten maakaapeleiden aiheuttamaa maasulkuvirran ja loistehon tuoton tasoa. Tulosten perusteel-la on tehty johtopäätökset mihin verkkoyhtiön on kiinnitettävä huomioita kaapelointeja suunnitellessa ja toteuttaessa.

Propuesta de Instrumentos de Promoción Dd Inversión Directa en el Extranjero Enfocados en Encadenamientos Productivos

La Inversión Directa en el Exterior representa el proceso más grande hacia la internacionalización de las empresas después de las exportaciones. Tal proceso significa una mejora en la competitividad de las empresas, traducida en mayor penetración en el mercado internacional, acceso a mejores tecnologías, recursos naturales e investigación. Este proyecto de investigación pretende formular una propuesta de instrumentos o servicios de promoción de inversión directa en el exterior, enfocados en encadenamientos productivos. En un primer lugar, se establecerá el marco teórico bajo el cual se desarrollara el proyecto, mediante la recolección de información relevante en teorías de internacionalización y en la descripción de encadenamientos productivos y clúster. En segundo lugar, se presentara el entorno macroeconómico y la evolución de los flujos de inversión directa en el extranjero en Colombia y Latinoamérica. Y finalmente, se hará un estudio comparativo de los servicios prestados por las principales agencias de promoción de inversión, que servirá de base para la posterior formulación de la propuesta de instrumentos de promoción de inversión.

Esquemas alternativos para o passo de parametrização do método da continuação baseados em parâmetros físicos

O método de fluxo de carga convencional é considerado inadequado para se obter o ponto de máximo carregamento (PMC) de sistemas de potência, devido à singularidade da matriz Jacobiana neste ponto. Os métodos da continuação são ferramentas eficientes para a solução deste tipo de problema, visto que técnicas de parametrização podem ser utilizadas para evitar a singularidade da matriz Jacobiana. Neste trabalho, novas opções para a etapa de parametrização do método da continuação são apresentadas. Mostra-se que variáveis com claro significado físico podem ser utilizadas na etapa de parametrização. As seguintes variáveis foram testadas: perda total de potência ativa e reativa, potência ativa e reativa na barra de referência, potência reativa das barras de geração, e as perdas de potência ativa e reativa nas linhas de transmissão (LT). Além de facilitar a implementação computacional do método de continuação, as técnicas de parametrização apresentadas simplificam a definição matemática e o entendimento do método por parte de engenheiros de potência, visto que os métodos de continuação existentes na literatura sempre utilizam técnicas de parametrização complexas, e de interpretação puramente geométrica. Resultados obtidos com a nova metodologia para os sistemas testes do IEEE (14, 30, 57 e 118 barras) mostram que as características de convergência do método de fluxo de carga convencional são melhoradas na região do PMC. Além disso, durante o traçado das curvas PV, as diversas técnicas de parametrização podem ser comutadas entre si possibilitando o cálculo de todos os pontos da curva com um número reduzido de iterações. Diversos testes são realizados para proporcionar a comparação do desempenho dos esquemas de parametrização propostos.

Photoelastic analysis of forces generated by T-loop springs made with stainless steel or titanium-molybdenum alloy

Introduction: The purpose of this study was to use photoelastic analysis to compare the system of forces generated by retraction T-loop springs made with stainless steel and titanium-molybdenum alloy (TMA) (Ormco, Glendora, Calif) with photoelastic analysis. Methods: Three photoelastic models were used to evaluate retraction T-loop springs with the same preactivations in 2 groups. In group 1, the loop was constructed with a stainless steel wire, and 2 helicoids were incorporated on top of the T-loop; in group 2, it was made with TMA and no helicoids. Results: Upon using the qualitative analysis of the fringe order in the photoelastic model, it was observed that the magnitude of force generated by the springs in group 1 was significantly higher than that in group 2. However, both had symmetry for the active and reactive units related to the system of force. Conclusions: Both springs had the same mechanical characteristics. TMA springs showed lower force levels. (Am J Orthod Dentofacial Orthop 2011;140:e123-e128)

Sensitivity analysis for overload-relief in transmission lines using an implicitly coupled method (CRIC)

The restructuring of energy markets to provide free access to the networks and the consequent increase of the number of power transactions has been causing congestions in transmission systems. As consequence, the networks suffer overloads in a more frequent way. One parameter that has strong influence on transfer capability is the reactive power flow. A sensitivity analysis can be used to find the best solution to minimize the reactive power flows and relief, the overload in one transmission line. The proposed methodology consists on the computation of two sensitivities based on the use of the Lc matrix from CRIC (Constant Reactive Implicitly Coupled) power flow method, that provide a set of actions to reduce the reactive power flow and alleviate overloads in the lines: (a) sensitivity between reactive power flow in lines and reactive power injections in the buses, (b) sensitivity between reactive power flow in lines and transformer's taps. © 2006 IEEE.

A specialized genetic algorithm to solve the short term transmission network expansion planning

In this paper, the short term transmission network expansion planning (STTNEP) is solved through a specialized genetic algorithm (SGA). A complete AC model of the transmission network is used, which permits the formulation of an integrated power system transmission network expansion planning problem (real and reactive power planning). The characteristics of the proposed SGA to solve the STTNEP problem are detailed and an interior point method is employed to solve nonlinear programming problems during the solution steps of the SGA. Results of tests carried out with two electrical energy systems show the capabilities of the SGA and also the viability of using the AC model to solve the STTNEP problem. © 2009 IEEE.

Continuous torque system with control of the reaction unit

This article describes an orthodontic system used to obtain active continuous torque with movement control of both active and reactive units; the system relies on principles of the segmented technique. A cantilever system with .017 x .025-in beta-titanium alloy wire was designed to provide the desirable moment on the active unit. A transpalatal bar or a lingual arch increases the anchorage and neutralizes the side effects on the reactive unit. This technique is an efficient approach for major corrections of buccolingual inclinations of certain teeth. © 2010 American Association of Orthodontists.

Aplicação da análise modal estática no estudo de estabilidade de tensão

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Alocação ótima de equipamentos SVC e TCSC na rede de transmissão de energia elétrica

Pós-graduação em Engenharia Elétrica - FEIS

Mixed-integer convex model for VAr expansion planning

This paper presents a mixed-integer convex-optimization-based approach for optimum investment reactive power sources in transmission systems. Unlike some convex-optimization techniques for the reactive power planning solution, in the proposed approach the taps settings of under-load tap-changing of transformers are modeled as a mixed-integer linear set equations. Are also considered the continuous and discrete variables for the existing and new capacitive and reactive power sources. The problem is solved for three significant demand scenarios (low demand, average demand and peak demand). Numerical results are presented for the CIGRE-32 electric power system.

On elimination of chaotic behavior in a non-ideal portal frame structural system, using both passive and active controls

In this paper, an application is considered of both active and passive controls, to suppression of chaotic behavior of a simple portal frame, under the excitation of an unbalanced DC motor, with limited power supply (non-ideal problem). The adopted active control strategy consists of two controls: the nonlinear (feedforward) in order to keep the controlled system in a desirable orbit, and the feedback control, which may be obtained by considering state-dependent Riccati equation control to bringing the system into the desired orbit using a magneto rheological (MR) damper. To control the electric current applied in control of the MR damper the Bouc-Wen mathematical model was used to the MR damper. The passive control was obtained by means of a nonlinear sub-structure with properties of nonlinear energy sink. Simulations showed the efficiency of both the passive control (energy pumping) and active control strategies in the suppression of the chaotic behavior. © The Author(s) 2012.