Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-02-23T19:26:50Z No. of bitstreams: 1 francianeconceicaopeters.pdf: 4730497 bytes, checksum: 201c60342a8bf9edc9b308fa50fafa54 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-02-24T12:08:43Z (GMT) No. of bitstreams: 1 francianeconceicaopeters.pdf: 4730497 bytes, checksum: 201c60342a8bf9edc9b308fa50fafa54 (MD5) / Made available in DSpace on 2017-02-24T12:08:43Z (GMT). No. of bitstreams: 1 francianeconceicaopeters.pdf: 4730497 bytes, checksum: 201c60342a8bf9edc9b308fa50fafa54 (MD5) Previous issue date: 2010-01-27 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A construção de imagens associadas à distribuição de condutividades no interior de um meio condutor a partir de injeção de corrente elétrica e medidas de potencial no contorno externo do corpo é uma técnica conhecida como tomografia por impedância elétrica. É um problema inverso que tem sido estudado visando aplicações biomédicas, monitoramento de processos industriais e investigação geofísica. Em alguns casos, é possível levar em consideração informações conhecidas sobre o domínio do corpo no processo de construção da imagem, recaindo no problema da detecção de inclusões que é o problema efetivamente tratado neste trabalho. Este problema pode ser resolvido por meio da minimização de uma função da diferença entre potenciais medidos no contorno e calculados para uma dada distribuição de condutividades. O presente trabalho desenvolve uma estratégia para a solução deste problema baseada na parametrização da geometria do contorno das inclusões cujas formas e dimensões se pretende determinar. O problema de minimização é resolvido por meio do Método de Levenberg-Marquardt e o problema direto via Método dos Elementos de Contorno. Para avaliar o desempenho da estratégia proposta são apresentados resultados numéricos envolvendo contornos definidos por splines, problemas com a presença de ruído nas medidas, avaliação de protocolos de injeção de corrente e medição de potencial elétrico e ainda uma aplicação voltada ao monitoramento cardíaco. / The images reconstruction of the conductivity distribution inside a conductive body based on electrical current injection and potential measurements on the outer boundary of this body is a technique known as electrical impedance tomography. This is an inverse problem that has been studied in biomedical applications, industrial process monitoring and geophysics investigation. In some cases, it is possible to take into account in the reconstruction process, informations about the body, leading to the problem of identifying inclusions, that is the problem actually treated in this work. This inverse problem can be solved by the minimization of a function, defined as the difference between the measured potentials and the computed ones for a given conductivity distribution. The present work describes a strategy to solve this problem based on the parametrization of the inclusions boundary, whose shape and size is intended to be determined. The minimization problem is solved via Levenberg-Marquardt Method and the forward one is solved via Boundary Elements Method. In order to evaluate the performance of the proposed strategy, numerical experiments with inclusions of boundaries defined by splines, problems with noisy data, current injection and potential measurement protocols and an application of the strategy to the cardiac function monitoring are presented.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-05-15T14:59:59Z No. of bitstreams: 1 marcoshenriquefonsecaribeiro.pdf: 12873424 bytes, checksum: 2b2b91fd2a9726856a0486afa760fe2c (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-17T16:01:12Z (GMT) No. of bitstreams: 1 marcoshenriquefonsecaribeiro.pdf: 12873424 bytes, checksum: 2b2b91fd2a9726856a0486afa760fe2c (MD5) / Made available in DSpace on 2017-05-17T16:01:12Z (GMT). No. of bitstreams: 1 marcoshenriquefonsecaribeiro.pdf: 12873424 bytes, checksum: 2b2b91fd2a9726856a0486afa760fe2c (MD5) Previous issue date: 2016-10-03 / A Tomografia por Impedância Elétrica (TIE) consiste em uma técnica onde imagens são construídas a partir da injeção de uma corrente elétrica em determinado meios, seguida da leitura de valores de potencial elétrico em pontos do contorno externo de tal domínio. Desta maneira, conhecendo-se ou estimando-se a condutividade elétrica de regiões internas ao meio, pode-se inferir aspectos geométricos da composição do mesmo. Trabalhos na literatura aplicam esta técnica ao contexto de obtenção de imagens do tórax humano, com objetivo de estimar a geometria das cavidades cardíacas de um determinado paciente. O objetivo final de estudo deste trabalho, dentro do contexto de aplicação da TIE à obtenção de cavidades cardíacas, é propor uma metodologia para a estimação da Fração de Ejeção Cardíaca, ou simplesmente Fração de Ejeção (FE), que consiste em medir o percentual de volume de sangue expulso dos ventrículos ao final de um ciclo de batimento do coração. Este trabalho visa evoluir outros trabalhos já existentes que modelam o problema acima descrito como sendo um problema inverso, de otimização, onde se pretende minimizar a diferença entre valores de potencial elétrico medidos e valores simulados por modelos computacionais. A evolução se dá em níveis diferentes. No primeiro nível, é feito um avanço sobre as técnicas de otimização para a resolução do problema inverso, em sua formulaçãobidimensional. Paratal, épropostaumametaheurísticaqueauxiliamétodosde buscanaobtençãodevaloresmaisacurados. Estametaheurísticaéapresentadaemversões sequencial e paralela. São apresentados resultados computacionais de testes realizados para este primeiro nível. Em um segundo nível, é feita a modelagem em três dimensões das mesmas abordagens já encontradas na literatura, que, para a aplicação específica da determinação da FE, até então estão limitadas a modelos bidimensionais. Assim, todo o problema é revisto para uma nova proposta de modelagem, que inclui a criação de modelos geométricos tridimensionais para as regiões de interesse do problema. Como principal contribuição do trabalho neste segundo nível, encontra-se um esquema de parametrização das malhas de polígonos que modelam ventrículos do coração, de forma que se tenha uma maneira compacta de representar as mesmas e, ao mesmo tempo, diminuindo o custo computacional do método de otimização por meio de drástica redução do número de variáveis do problema. Por fim, também é realizado um estudo preliminar da sensibilidade da técnica à presença de ruídos nos dados de entrada. / The Electrical Impedance Tomography (EIT) consists in a technique where images are constructed from the measurements of the electrical potential in some points on the external boundary of some specific domain, caused by the injection of an electrical current in such domain. This way, knowing or estimating the electrical conductivity of some regions inside the domain, geometric aspects of the composition of that domain can be inferred. Works in literature apply this technique to the context of obtaining images from the human thorax, with the objective of estimating the geometry of some cardiac cavities of a specific patient. The final goal of this work, inside the context of the obtention of cardiac cavities, is to propose a methodology for estimating the Cardiac Ejection Fraction, orsimplyEjectionFraction(EF),whichconsistsinmeasuringthepercentualofthevolume of blood expelled from the ventricles at the end of a heart beat cicle. This work intends to evolute previous works, that models the above mentioned problem as an inverse problem, an optimization problem, where the intention is to minimize the difference between the values of measured electrical potentials and the values obtained through simulation using computational models. This evolution occurs in different levels. In the first level, is performedanimprovementoverthepre-existentoptimizationtechniquesforthesolutionof theinverseproblem,inatwodimensionalversion. Forthis,isproposedametaheuristicthat assistssearchmethodstowardstheobtentionofmoreaccuratedvalues. Suchmetaheuristic is presented in sequential and parallel versions. Computational results for performed tests for this level are presented. In a second level, a three dimensional modeling of the same approaches found in literature is done. Those approaches, for the specific application of determining the EF, are so far limited to two dimensional models. Therefore, the whole problem is reviewed in order to propose a new model, which includes the creation of three dimensional geometric models for the regions of interest of the problem. As the main contribution of this work in that second level, there is a parameterization schema of the polygon meshes that model heart ventricles, so that it provides a compact way of representing such meshes, and, at the same time, a way of reducing the computational cost of the optimization method by means of a drastic reduction of the number of variables of the problem. Finally, a preliminary study of the sensibility of the technique to the presence of noise in the input data is also performed.

The diploma thesis is focused on an adaptive control, especially in a self-tuning controller area. The thesis is divided into two main parts. The first part deals with identification methods of the adaptive control. The recursive least squares algorithm and the neural network method are the most popular identification methods. These methods are contrasted and the identification quality evaluation is done. The second part compares various types of the adaptive controllers with a non-adjustable PSD controller. The adaptive controllers are investigated from the various identification method point of view. The user graphic interface was realized for the identification and regulatory part. The time behavior of system responses after incoming disturbance and dynamic process changes during simulation systems control is compared with a physical model connected to B&R PLC. The comparison is done with the application of Matlab/Simulink program.

This bachelor thesis is written for KTH Royal Institute of Technology and Ymer Technology AB. It examines the friction factor associated with the pressure drop in wavy-fin heat exchangers. Previous studies have used a nonlinear approach for determining the regression coefficients. This study introduces a linearizing transform that solves the issues of finding non-optimal parameter values stemming from the current nonlinear approach. The linearization also drastically improves the computational time. A final model explaining 95.4\% of the variance in the data is presented. Methods for avoiding overfitting, detecting outliers and hidden extrapolation are presented and used to evaluate the model. The implications of the mathematical results on improving profit, competitiveness, and customer relationships are analyzed in the second part of the report with a qualitative approach. / Denna kandidatuppsats är skrivet vid Kungliga Tekniska Högskolan och Ymer Technology AB. Det undersöker den friktionsfaktor som associeras med tryckfallet i kylare med wavy-fins. Tidigare studier har använt ett ickelinjärt tillvägagångssätt för att bestämma regressionskoefficienterna. Denna studie introducerar en linjäriserande transform som löser problemen med att hitta icke-optimala paramatervärden, som härstammar från tidigare icke-linjära tillvägagångsätt. Linjäriseringen visar sig även förbättra beräkningstiden drastiskt. En slutgiltig modell som förklarar 95\% av variansen i datan presenteras. Metoder för att undvika overfitting, identifiera outliers, och undvika att falla offer för gömd extrapolation presenteras och används för att evaluera modellen. De matematiska resultatens implikationer för Ymer med avseende på vinst, konkurrenskraft och kundrelationer, analyseras i den andra delen av rapporten med en kvalitativ ansats.

Ce projet de recherche porte sur deux problématiques différentes, cependant, elles partagent les mêmes phénomènes physiques. Il s’agit de la prédiction inverse de l’évolution temporelle du front de solidification : (1) dans les réacteurs métallurgiques à haute température et (2) dans les tissus vivants pendant la cryochirurgie. Problématique #1 : Afin de réduire l’érosion et l’agression chimique des parois internes de briques réfractaires par la matière en fusion au sein des réacteurs métallurgiques, on laisse croître par changement de phase solide/liquide une couche protectrice sur leur surface interne. Cette couche joue un rôle extrêmement important, car elle assure l’intégrité de l’installation et prolonge sa durée de vie. Toutefois, une couche protectrice trop épaisse réduit le volume utile de réacteur et diminue ainsi la production industrielle. Le défi, pour l’industriel, consiste alors à exploiter ces réacteurs tout en maintenant une couche dont l’épaisseur est optimale. L’environnement hostile qui règne au cœur du réacteur interdit toutefois les mesures directes. Les sondes qu’on y plonge sont détruites. Pour remédier à ce problème, l’industriel recourt à la simulation numérique et, plus récemment, à une approche par transfert inverse. Cette thèse présente une procédure inverse de transfert de chaleur qui permet, à partir des mesures de température non invasives provenant d’un thermocouple situé dans les parois extérieures de briques, de prédire simultanément les paramètres thermiques inconnus ainsi que l’épaisseur de la couche protectrice au sein des réacteurs métallurgiques. La technique inverse repose sur la méthode de Levenberg-Marquardt (LMM) combinée avec la méthode de Broyden (BM). La Problématique #2 aborde quant à elle la cryochirurgie. C’est une technique récente, peu invasive, qui utilise le froid extrême pour détruire les tissus indésirables tels que les tumeurs. Elle s’adresse donc à des tumeurs internes et externes. L’objectif de la cryochirurgie est de détruire les tumeurs tout en minimisant les dommages des tissus sains adjacents. La fiabilité de cette technique dépend d'un certain nombre de paramètres thermiques tels que la température de la cryosonde, les propriétés thermiques des tissus, la durée de congélation, etc. Pour y parvenir, des méthodes expérimentales et numériques ont été développées. Cependant, chaque méthode a ses propres limites. En effet, le problème majeur est associé à la méconnaissance de certains paramètres thermiques, ce qui rend l’analyse de la transmission dans les tissus biologiques difficile. Pour pallier ces limites et améliorer la technique de cryochirurgie, une approche novatrice est retenue : il s’agit du transfert de chaleur inverse. À partir de mesures thermiques de températures provenant d’un thermocouple implanté dans la tumeur, cette approche permet de prédire les paramètres inconnus tels que la perfusion sanguine et, ensuite, de déterminer l’évolution temporelle de l’interface de congélation et la distribution de la température dans le tissu.

Dans la fabrication d'un produit, la maîtrise des propriétés physiques des matériaux utilisés est indispensable. Il est donc nécessaire de déterminer leurs propriétés comportementales. On exploite en général des propriétés physiques intermédiaires telles que les propriétés électromagnétiques. Nous avons mis au point une technique de caractérisation sans contact de matériaux non transparents en transposant les concepts de base de l'ellipsométrie optique en hyperfréquence. La caractérisation se fait par résolution d'un problème inverse par deux méthodes numériques : une méthode d'optimisation classique utilisant l'algorithme itératif de Levenberg Marquardt et une méthode de régression par l'uti1isation de réseaux de neurones du type perceptron multicouches. Avec la première méthode, on détermine deux paramètres du matériau sous test à savoir l'indice de réfraction et l'indice d'extinction. Avec la deuxième, on détermine les deux indices ainsi que l'épaisseur de 1'échantillon. Pour la validation, nous avons monté un banc expérimental en espace libre à 30 GHz en transmission et en incidence oblique avec lequel nous avons effectué des mesures sur des échantillons de téflon et d'époxy de différentes épaisseurs (1 à 30 mm). Nous avons obtenu une caractérisation satisfaisante de l'indice et de l'épaisseur. Nous avons ensuite fait des mesures de trois types de papier dont la caractérisation de l'indice était satisfaisante sans toutefois les discriminer. Ces travaux ont montré la possibilité de caractériser des matériaux épais et non transparents par une technique ellipsométrique

Master of Science / Department of Civil Engineering / David R. Steward / Accurate modeling of the High Plains Aquifer depends on the availability of good data that represents and quantities properties and processes occurring within the aquifer. Thanks to many previous studies there is a wealth of good data available for the High Plains Aquifer but one key component, groundwater-surface water interaction locations and rates, is generally missing. Without these values accurate modeling of the High Plains Aquifer is very difficult to achieve. This thesis presents methods for simplifying the modeling of the High Plains Aquifer using a sloping base method and then applying mathematical optimization techniques to locate and quantify points of groundwater-surface water interaction. The High Plains Aquifer has a base that slopes gently from west to east and is approximated using a one-dimensional stepping base model. The model was run under steady-state predevelopment conditions using readily available GIS data representing aquifer properties such as hydraulic conductivity, bedrock elevation, recharge, and the predevelopment water level. The Levenberg-Marquardt and particle swarm algorithms were implemented to minimize error in the model. The algorithms reduced model error by finding locations in the aquifer of potential groundwater-surface water interaction and then determining the rate of groundwater to surface water exchange at those points that allowed for the best match between the measured predevelopment water level and the simulated water level. Results from the model indicate that groundwater-surface water interaction plays an important role in the overall water balance in the High Plains Aquifer. Findings from the model show strong groundwater-surface water interaction occurring in the northern basin of the aquifer where the water table is relatively shallow and there are many surface water features. In the central and southern basins the interaction is primarily limited to river valleys. Most rivers have baseflow that is a net sink from groundwater.

This thesis examines how to find the best fit to a series of data points when curve fitting using power-exponential models. We describe the different numerical methods such as the Gauss-Newton and Levenberg-Marquardt methods to compare them for solving non-linear least squares of curve fitting using different power-exponential functions. In addition, we show the results of numerical experiments that illustrate the effectiveness of this approach.Furthermore, we show its application to the practical problems by using different sets of data such as death rates and rocket-triggered lightning return strokes based on the transmission line model.

<p>The study of Surface Air Cooled Oil Coolers (SACOC) is motivated by the need for new cooling concepts for compact machinery designs with high thermal load. Installing finned heat exchangers in the bypass duct of a turbofan engine provides an additional cooling source having transonic flow as a heat sink. The characterization of the heat transfer and the aerodynamics of the design are essential to minimize the impact on the overall efficiency of the engine. In the present study, the SACOC is studied numerically and experimentally. Two geometries are tested in a high-speed linear wind tunnel where measurements are taken with multiple sensors and optical techniques. For the heat transfer characterization, an Inverse Heat Conduction Methodology (IHCM) based on a Levenberg-Marquardt Algorithm is developed. The experimental results are matched to numerical simulations using a Reynolds Averaged Navier-Stokes (RANS) solver. Finally, a multi-objective optimization algorithm is coupled <a>with the RANS solver</a> to explore new geometries that maximize the heat transfer and minimize the pressure drop across the studied domain. The 400 profiles generated allow for the identification of the features that have a higher influence on the performance of the fins and six profiles that present large improvements are chosen for further analysis.</p>

A number of non-invasive fault detection and diagnosis (FDD) techniques have been researched and have proven to have worked well in classifying faults in internal combustion engines (ICE) and other mechanical and electrical systems. These techniques are an integral step to creating more robust and accurate methods of determining where or how a fault has or will occur in such systems. These FDD techniques have the potential to not only save time avoiding a tear-down of a costly machine, but could potentially add another layer of safety in detecting and diagnosing a fault much earlier than was possible before. Looking at the previous research methods and the systems they used to acquire this data, it is a natural progression to try and make a system which is able to encapsulate all of these ideologies into one inexpensive module capable of integrating itself into the advanced set of FDD. This thesis follows along with the development of a new wireless sensor that is developed specifically for the use in FDD for ICE and other mechanical systems. A new set of software and firmware is created for the system to be able to be incorporated into previously designed algorithms. After creating and manufacturing the sensor it is put to the test by incorporating it into several Artificial Neural Networks (ANN) and comparing the results to previous experiments done with previous research equipment. Using vibration data acquired from a running engine to train a neural network, the wireless sensor was able to perform equally as well as its expensive counter parts. It proved to have the ability to achieve 100% accuracy in classifying specific engine faults. The performance of three ANN training algorithms, Levenberg-Marquardt (LM), extended Kalman Filter (EKF), and Smooth Variable Structure filter (SVSF), were tested and compared. Adding to the feasibility of a standalone system the wireless sensor was tested in a live environment as a method of instant ICE fault detection. / Thesis / Master of Applied Science (MASc)