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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The Brain Correlates of Personality and Sex Differences

Fair, Brittany 01 January 2018 (has links)
Personality neuroscience is a rapidly expanding field of study fueled by a growing interest in understanding the structural brain correlates of individual differences in personality. Data on the structural brain correlates of personality are especially lacking from large-scale studies, and are nearly nonexistent in the adolescent age group. Furthermore, the role of sex differences in structural brain changes associated with personality are rarely considered. To address this gap in knowledge, this thesis investigates the structural brain correlates of personality and sex differences in structure at age fourteen. A large sample of adolescents (N = 2000) were drawn from the IMAGEN project. Data on adolescents’ puberty status, IQ, and personality were collected through adolescent-reported questionnaires and interviews. The structural brain correlates of personality were examined utilizing personality variables from the NEO Five Factor Inventory (NEO-FFI) and Voxel-Based Morphometry (VBM). Our results showed few correlations between any dimension of the NEO-FFI and regional grey matter volume (GMV). In the total sample, a negative correlation was found for agreeableness and bilateral supplementary motor area (SMA), which was also present in the male subsample. The female sample showed a significant negative correlation between extraversion and the right SMA, and a positive correlation in the left cerebellum. A non-linear effect of extraversion positively correlated with the right precuneus in females. The present study suggests personality traits are not strongly reflected in GMV during adolescence. This thesis includes a discussion on future directions and suggestions for assessing the brain correlates of personality.
2

Sistema de controle para termociclador

Corte, Angélico 19 September 2016 (has links)
Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-12-23T11:33:24Z No. of bitstreams: 1 Angélico Corte_.pdf: 3793672 bytes, checksum: 4f2c36a99d97bd11708bd259e853a7fb (MD5) / Made available in DSpace on 2016-12-23T11:33:24Z (GMT). No. of bitstreams: 1 Angélico Corte_.pdf: 3793672 bytes, checksum: 4f2c36a99d97bd11708bd259e853a7fb (MD5) Previous issue date: 2016-09-19 / Nenhuma / O termociclador é um equipamento utilizado para realizar uma técnica de biologia molecular chamada PCR (Polymerase ChainReaction – Reação em Cadeia da Polimerase), que objetiva isolar e amplificar fragmentos alvo de DNA e é amplamente utilizada em pesquisas nas áreas das ciências biológicas, saúde, agropecuária, em diagnósticos animal, vegetal e humano, bem como na medicina forense.O funcionamento do equipamento consiste em realizar ciclos de temperatura variáveis, sendo que o sucesso da reação depende basicamente de três fatores: (1) a velocidade das rampas de subida e descida de temperatura; (2) a precisão e estabilidade da temperatura estipulada no programa; (3) oovershoot reduzido ao final das rampas de temperatura. Esta pesquisa foi desenvolvida como a primeira fase de um projeto de nacionalização de tecnologia. Osobjetivosforam descobrir qual o controlador que melhor atua para o controle de temperatura em termocicladores e montar um protótipo deste equipamento.Os controladores testados foram os tipos PID (Genérico, ISA, Paralelo e com Síntese de Dahlin) e GMV.Esses controladores foram simulados usando Matlab e posteriormente implementados em um sistema de hardware. Foram implementadas no controlador PID de Dahlin, durante esse trabalho, a inserção de duas variáveis de ganho na componente proporcional, uma componente proporcional extra, um saturador e um filtro para acelerar a rampa de descida.Essas melhorias permitiram a resolução dos problemas apresentados pelos controladores, já que nenhum dos testados apresentou resultados satisfatórios em sua forma original.O protótipo foi montado e testado no laboratório de biologia molecular da Unisinos. O mesmo apresentou resultados equivalentes aos do equipamento importado em uso no laboratório. / The thermocycler is an equipment used to perform a molecular biology technique called PCR (Polymerase Chain Reaction), which aims at amplifying target DNA fragments. It is widely used in biology, health and agriculture sciences, animal, plant and human diagnostics, as well as in forensics. The equipment completes variable temperature cycles, and the success of the technique relies on three factors: (1) increasing and decreasing ramp rates; (2) temperature accuracy and stability of the temperatures set in the program; (3) a reduced overshoot at the end of each temperature ramp. This research was developed as the first phase of a Technology Nationalization Project. The aim was to identify the best controller to regulate temperature in thermal cycles and assemble a prototype of such equipment. The controllers tested were PID(Generic, ISA, Parallel and Dahlin Synthesis) andGMV. These controllers were simulated using Matlab and then, implemented in a hardware system. The following improvements were implemented in the Dahlin PID Controller during this work: addition of two gain variables in the proportional component, an extra proportional component, one saturator and a filter to accelerate the decreasing ramp. Such improvements allowed us to solve the problems of the controllers, as none of them presented acceptable results in its original form. The prototype was assembled and tested in the Molecular Biology Laboratory of Unisinos. The PCR results obtained with the prototype were equivalent as those obtained from the imported equipment used regularly in the laboratory.
3

Controle adaptativo com desacoplamento aplicado a um sistema de tanques acoplados MIMO

Paulo, Thiago Ferreira 31 July 2015 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-07-08T21:04:13Z No. of bitstreams: 1 ThiagoFerreiraPaulo_DISSERT.pdf: 1256106 bytes, checksum: 42270ab696a6a5783b3e620be87e6519 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-07-12T18:19:22Z (GMT) No. of bitstreams: 1 ThiagoFerreiraPaulo_DISSERT.pdf: 1256106 bytes, checksum: 42270ab696a6a5783b3e620be87e6519 (MD5) / Made available in DSpace on 2016-07-12T18:19:22Z (GMT). No. of bitstreams: 1 ThiagoFerreiraPaulo_DISSERT.pdf: 1256106 bytes, checksum: 42270ab696a6a5783b3e620be87e6519 (MD5) Previous issue date: 2015-07-31 / O controle de sistemas MIMO (Multiple Input Multiple Output) ? muitas vezes realizado por v?rias malhas de controladores cl?ssicos que operam com restri??es e apresentam baixo desempenho. T?cnicas de controle adaptativo s?o uma alternativa interessante para aumentar o rendimento desses sistemas, como por exemplo os controladores MRAC (Model Reference Adaptive Control), que quando bem projetados, permitem que a din?mica da planta seja escolhida de maneira a seguir um modelo de refer?ncia. O presente trabalho apresenta uma estrat?gia de desacoplamento para um sistema MIMO de tr?s tanques acoplados e o projeto de um controlador MRAC para o mesmo.
4

Portfolio Optimization : A DCC-GARCH forecast with implied volatility

Bigdeli, Sam, Bengtsson, Filip January 2019 (has links)
This thesis performs portfolio optimization using three allocation methods, Certainty Equivalence Tangency (CET), Global Minimum Variance (GMV) and Minimum Conditional Value-at-Risk (MinCVaR). We estimate expected returns and covariance matrices based on 7 stock market indices with a DCC-GARCH model including an ARMA (1.1) process and an external regressor of an implied volatility index (VIX). We then simulate returns using a rolling window of 500 daily observations and construct portfolios based on the allocation methods. The results suggest that the model can sufficiently estimate expected returns and covariance matrices and we can outperform benchmarks in form of equally weighted and historical portfolios in terms of higher returns and lower risk. Over the whole out-of-sample period the CET portfolio yields the highest mean returns and GMV and MinCVaR can significantly lower the variance. The inclusion of VIX has marginal effects on the forecasting accuracy and it seems to impair the estimation of risk.
5

Controlador GMV aplicado à regulação do ângulo de passo em um sistema de conversão de energia eólica: uma abordagem linear, preditiva e estocástica

SILVA, Anderson de França 07 April 2017 (has links)
Submitted by Hellen Luz (hellencrisluz@gmail.com) on 2017-07-03T18:08:03Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_ControladorGMVAplicado.pdf: 4787689 bytes, checksum: 5369a6da858d594a439c7bbc0f0a5c05 (MD5) / Approved for entry into archive by Irvana Coutinho (irvana@ufpa.br) on 2017-08-17T15:13:05Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_ControladorGMVAplicado.pdf: 4787689 bytes, checksum: 5369a6da858d594a439c7bbc0f0a5c05 (MD5) / Made available in DSpace on 2017-08-17T15:13:05Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_ControladorGMVAplicado.pdf: 4787689 bytes, checksum: 5369a6da858d594a439c7bbc0f0a5c05 (MD5) Previous issue date: 2017-04-07 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesta pesquisa, foram investigadas técnicas de controle linear, preditivo e estocástico, aplicadas ao problema de regulação do ângulo de passo de uma Turbina Eólica. A topologia do Sistema de Conversão de Energia Eólica (SCEE) estudado é do tipo Velocidade Fixa, com ângulo de passo variável. Os SCEE, de maneira geral, são sistemas que, durante seu funcionamento, estão sujeitos à constante entrada de perturbações do tipo estocásticas. Este tipo de perturbação, em muitos casos, é negligenciado, o que afeta o desempenho de controladores cujo o projeto foi baseado em modelos determinísticos. Pesquisas desenvolvidas na da Teoria de Controle Preditivo e Estocástico, têm comprovado os benefícios de se realizar o projeto de controladores baseados em modelos que consideram as parcelas, determinística e estocástica, do processo. Seguindo esta mesma abordagem de projeto, foi desenvolvido, nesta dissertação, o projeto de Reguladores do Ângulo de Passo (RAP), por meio da técnica de Argmentação Estocástica (AE) de controladores determinísticos. Os principais objetivos buscados foram: minimizar o consumo de energia do sistema de controle; e reduzir os custos relacionados à manutenção e troca dos atuadores no sistema de regulação do ângulo de passo. Foram realizados testes em um simulador de SCEE da MathWorks®. Os resultados dos testes comprovam o bom desempenho dos RAP projetados através da AE, os quais alcançaram os objetivos buscados no desenvolvimento desta pesquisa. / In this research, we investigated linear, predictive and stochastic control techniques applied to the pitch angle control of a Wind Turbine. The topology of the Wind Energy Conversion System (WECS) studied was the Fixed-Speed Variable-Pitch. The WECS, in general, is a system that, during their operation, is subject to the constant entry of stochastic disturbances. This type of disturbance is often neglected, which will negatively affect the performance of controllers whose design was based on deterministic models. Researches developed within the Predictive and Stochastic Control Theory, have proven the benefits of performing the design of controllers based on models that consider both the deterministic and stochastic portions of the process. Following this same design approach, the Picth Angle Control (PAC) project was developed, in this dissertation, using the Stochastic Augmentation (SA) of deterministic controllers. The main objectives sought, were: to minimize the energy consumption of the control system; and to reduce the costs related to the maintenance and replacement of actuators in the pitch angle control system. Simulation tests were performed on a MathWorks® WECS simulator. The results of the tests have proved the good performance of the PAC designed through the SA, which reached the control objectives sought with the development of this research.

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