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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.
131

Monitoramento da Integridade Estrutural de Sistemas Mecânicos via Observador de Estado Modal /

Cavalini Junior, Aldemir Aparecido. January 2009 (has links)
Resumo: O monitoramento da integridade estrutural (SHM) de sistemas mecânicos trata-se de uma tecnologia emergente que combina modernos sensores com inteligentes algoritmos computacionais para analisar a condição da estrutura em tempo real ou quando for necessário. Segurança, alto desempenho em operação e redução nos custos de manutenção são alguns dos principais benefícios concedidos pela tecnologia SHM. Deste modo, esta tecnologia vem encontrando aceitação crescente na indústria, principalmente na aeronáutica e petrolífera onde os custos de manutenção são muito elevados. Dentre as técnicas de monitoramento desenvolvidas, a dos observadores de estado se destacou. No entanto, esta técnica SHM possui algumas restrições que motivam o interesse pelo desenvolvimento de uma nova abordagem para a mesma. Neste contexto, este trabalho alia os já conhecidos observadores de estado com as características do domínio modal a fim de determinar o modo de vibrar mais afetado pela presença de um dano qualquer no sistema monitorado. A partir do conhecimento desta informação é possível projetar, por exemplo, sistemas de controle e manutenção mais eficientes. Contudo, nesta dissertação são apresentadas aplicações numéricas e experimentais em diferentes sistemas mecânicos a fim de detalhar e demonstrar a técnica SHM via Observador de Estado Modal, inicialmente proposta aqui. Algumas destas aplicações contam ainda com sensores e atuadores piezelétricos acoplados as estruturas. Os resultados encontrados mostram pontos favoráveis e desfavoráveis da técnica proposta / Abstract: Structural Health Monitoring (SHM) is an emerging technology that combines modern sensors with intelligent algorithms to analyze the structural condition in real time or specific time. Security, high operation performance and maintenance reduction costs are some of the key benefits provided by this technology. Not surprisingly, the SHM techniques have recently received increased attention in aircraft and oil industries. Among the developed SHM techniques, state observers had special attention. However, this technique presents some restrictions that motivate the development of a new SHM approach through state observers. In this context, this work associates the already known state observers with features obtained in the modal domain to determine the vibration modes that are more affected by damage presence in the monitored structure. That information makes possible the design of efficient maintenance and control systems. In order to analyze the Modal State Observer technique, firstly presented here, numerical and experimental applications in different mechanical systems are presented. In some applications are used sensors and piezoelectric actuators coupled in the structures. The results lead to the conclusion that the Modal State Observer is a potential useful SHM tool / Orientador: Gilberto Pechoto de Melo / Coorientador: Vicente Lopes Junior / Banca: Luiz de Paula do Nascimento / Banca: Valder Steffen Junior / Mestre
132

Projeto de um observador passivo não-linear e de um controlador backstepping para navios de superfície. / Design of a passive nonlinear observer and a backstepping controller for surface vessels.

Alexis Zakartchouk Junior 05 January 2010 (has links)
Sistemas de Posicionamento Dinâmico (SPD) são sistemas de controle que visam assegurar que um veículo oceânico se mantenha em uma determinada posição ou acompanhe uma trajetória de referência, mediante o emprego exclusivo de seus propulsores. Um SPD pode ser desmembrado em vários módulos específicos, com funções bem determinadas. Os módulos mais importantes são os sistemas de medição de posição e aproamento, o estimador de estados, o controlador e o algoritmo de alocação de empuxos. Atualmente, o Filtro de Kalman Estendido (FKE) é o estimador padrão para todos os SPD comercialmente disponíveis. Entretanto, o emprego do FKE implica em uma série de desvantagens. A sintonização do sistema é demorada e difícil, em função do elevado número de parâmetros de sintonização. Estabilidade assintótica global não pode ser conferida ao sistema. Adicionalmente, é necessário aplicar a técnica de programação de ganhos, uma vez que as equações cinemáticas de movimento do modelo devem ser linearizadas para aproximadamente 36 ângulos de guinada. A fim de eliminar estes óbices, o presente estudo propõe o desenvolvimento de um SPD totalmente não-linear, composto por um observador passivo não-linear e um controlador não-linear backstepping. / Dynamic Positioning Systems (DPS) are control systems used to maintain the vessel on a desired position or pre-defined path exclusively by means of active thrusters. A DPS can be separated into a set of dedicated modules with designated tasks. The most significant modules are the position and heading measurement systems, the state estimator, the controller and the thrust allocation algorithm. Nowadays, the Extended Kalman Filter (EKF) is the standard state estimator for all commercial DPS. However, the EKF technique presents several drawbacks. There is a large number of tuning parameters which requires a time-consuming tuning procedure. Global asymptotic stability cannot be assured to the system. Furthermore, it requires the use of a gain-scheduling technique, since the model is linearized about approximately 36 yaw angles due to the kinematics equations of motions. To solve these problems, this study proposes the development of a fully nonlinear DPS comprising a passive nonlinear observer and a nonlinear backstepping controller.
133

Normatização de Protocolo de Observação Comportamental (PROC): aspectos comunicativos e cognitivos de crianças com desenvolvimento típico de linguagem / Standardization of Behavioral Observation Protocol (PROC): communicative and cognitive aspects of children with typical language development

Tatiane Cristina Pereira 27 February 2012 (has links)
Um grande número de crianças com menos de quatro anos de idade procura serviços de atendimento fonoaudiológico por estarem apresentando suspeitas de dificuldades quanto ao desenvolvimento adequado da linguagem. Entretanto, apesar de tal demanda, o fonoaudiólogo clínico ainda não encontra à sua disposição procedimentos sistematizados de avaliação que possam auxiliá-lo no sentido de promover um diagnóstico adequado. No intuito de contribuir para o delineamento do perfil comunicativo e cognitivo de crianças pequenas, este trabalho teve por objetivo obter valores de referência para protocolo de observação comportamental (PROC) sobre o desenvolvimento de habilidades comunicativas e de esquemas simbólicos em crianças com desenvolvimento típico de linguagem. Foram avaliadas 44 crianças entre 24 e 47 meses de ambos os gêneros, selecionadas em escolas de educação infantil, por meio de triagem do desenvolvimento global Denver II (TTDD II) e questionário com os pais. Todas as crianças foram filmadas durante 30 minutos em interação com um adulto em atividade envolvendo brinquedos. As gravações foram analisadas por meio do PROC. A análise estatística descreveu valores de média, mediana, valores mínimos e máximos. Foi utilizado o teste T de Student para comparação das idades. Foi considerado significativo valor de p<0,05. No que tange às habilidades comunicativas, as crianças do estudo mostraram evolução com a idade (média para três e dois anos, respectivamente: 58,12 e 51,44), apesar de não ter sido encontrada diferença estatisticamente significante para as faixas etárias comparadas (p=0,486). Na análise dos subitens habilidades dialógicas e funções comunicativas, a média das pontuações obtidas foram semelhantes para as duas faixas etárias, sendo que a função mais observada foi a instrumental para ambas. Já para os subitens meios de comunicação e nível de contextualização da linguagem, as crianças de três anos apresentaram maior pontuação. Quanto ao item compreensão verbal, as crianças de três anos obtiveram melhor desempenho que as de dois (respectivas médias: 59,41 e 50,70), havendo diferença estatisticamente significante (p=0,0000020). Em relação ao item aspectos do desenvolvimento cognitivo, as crianças de três anos apresentaram melhor desempenho em comparação com as de dois (respectivas médias: 44,53 e 31,96), havendo diferença estatisticamente significante entre as pontuações obtidas (p=0,00364), mostrando que as crianças evoluem na hierarquia do simbolismo. Em relação aos subitens forma de manipulação dos objetos, nível de desenvolvimento do simbolismo, nível de organização do brinquedo e imitação, as crianças de três anos obtiveram melhor pontuaçao que as de dois, excetuando-se no subitem Imitação. Portanto, na pontuação total do instrumento PROC, considerando todos os três itens avaliados, as crianças de três anos obtiveram maior pontuação em comparação às de dois, havendo diferença estaticamente significante entre os valores obtidos paras as faixas etárias, excetuando-se para o item Habilidades Comunicativas. A obtenção de valores de referência para o PROC veio combinar análise qualitativa e quantitativa, contribuindo, além do diagnóstico, para o acompanhamento objetivo de processos terapêuticos. / A large number of children under 4 years old go to speech therapy services because they are presenting difficulties on appropriate language development. However, although this demand, the speech pathologist does not have at his disposal systematized assessment procedures that can assist in promoting a proper diagnosis, differentiating possible language problems affecting this age group, or even make the appropriate guidance of the case, in terms of therapy, in terms of referrals to other professionals. In order to create standard procedures to contribute to a better evaluation of language development in children, this study aims to obtain reference values for behavioral observation protocol (PROC) on the development of communicative and symbolic schemes of children with typical language development. It has been evaluated 44 children between 24 and 47 months, both genders, selected from three different primary schools using Denver II development screening methodology (TTDD II) and also a questionnaire submitted to the parents. All children were filmed 30 minutes interacting with the researcher and playing with toys. The recordings were analyzed through PROC. The values that compose the statistical analysis are average, median, maximums and minimums. It has been used the T Student test to compare the ages. The significance was p<0.05. In regards to communication abilities, children had shown an evolution with age (average of three and two years old respectively 58.12 and 51.44), even though no significant statistical change was found in the range of ages compared (p=0.486). In the sub-item analysis performed over dialogical abilities and communication functions, the averages were similar for both age groups, being the instrumental function the one most observed. For the sub-items communication medium and language contextualization level, the three years old children had higher scores. In regards do verbal comprehension, children aged three presented better results than children aged two (averages: 59.41 and 50.70 respectively) with statistical significance variance (p=0.0000020). In cognitive development, three years old children presented better performance compared to two years old children (averages: 44.53 and 31.96 respectively), significant difference between results (p=0.00364) showing that children evolve in the hierarchy of symbolism. In the sub-items object manipulation, symbolism development level, toys organization level and imitation, three years old children had also better score than two years old children, except for imitation. Therefore, the total score of PROC, considering the three items evaluated, showed better results for three years old children compared to two years old children with significant statistical difference between the group ages, except for communication abilities. The values obtained in PROC combined qualitative and quantitative analysis, contributing, besides diagnosis, to a more objective therapeutic process evaluation.
134

Da experiência do Usuário midiático contemporâneo: olhares em construção. / Of the contemporary mediatic User experience: perspectives under development.

Claudia Erthal 07 May 2018 (has links)
Esta pesquisa desenvolve uma análise crítica a partir de uma noção histórico-teórica do processo de construção da relação das pessoas com a mídia na contemporaneidade e está dividida em três momentos: o Observador no século 19; o Espectador no século 20; e o Usuário no século 21. Assume que estes constituem três sujeitos comunicacionais, possuem trajetórias interligadas e podem ser vistos como um sujeito múltiplo. O trabalho parte dos seguintes pressupostos: a transformação do comportamento dos sujeitos; o acúmulo de percepções e conhecimentos; e as mudanças nos modos de ver e nas maneiras de se relacionar que se dão a partir de uma construção sociocultural, política e econômica. Busca compreender a existência de um Observador/Espectador/Usuário e as mediações tecnológicas que lhe servem como contexto. Vê o Usuário: a partir do Flanêur de Benjamin - como uma referência comunicacional ao sujeito/objeto na formação do seu olhar; como reconfiguração do sujeito/receptor na história e de sua relação com a mídia e com a sociedade; como a dimensão tecnológica permeia a diferenciação dos sujeitos comunicacionais e o contexto social no qual estão inseridos, privilegiando a tecnologia e em seu lugar político e social, e de como o comportamento deste sujeito pode ser atribuído a esses lugares. Trabalha a Percepção na medida em que se aproxima do Usuário/Flanêur numa conjugação em que os dois se distinguem mesmo que em tempos e circunstâncias diversas na experiência comunicacional. / This research develops a critical analysis from a historical-theoretical perception of the construction process of people relation with the Media in the contemporary world and it is divided in three moments: the Observer in the 19th century; the Spectator in the 20th century and the User in the 21st century. It accepts that these three communication subjects share connected paths and can also be seen as a multiple subject. This work is based in the following assumptions: the transition in the subjects behaviour; the accumulation of perception and knowledge; and the changes in the ways of seeing and in the ways the relationships happened from a sociocultural, political and economic structure point of view. The research aims to understand the existence of an Observer/Spectator/User and the technological mediations that are used as a background. It sees the User from: Benjamin\'s Flanêur point of view - as a communicational reference for the development of the subject/object in the construction of the way he sees; as a reconfiguration of the subject/recipient in history and its relation with the Medias and with the society; how the technological dimension pervades the variation between the communication subjects and in the social context in which they are located, with a particular emphasis in technology, and in his political and social place and of how this subjects\' behaviour is ascribed to these places. This research also explores the Perception to the extent that it approaches the User/Flanêur in a combination in which the two of them distinguish from each other in the communication experience even in different times and circumstances.
135

Modelling and Simulation of a Resonant Converter

Kolachina, Srinivasa Kranthi Kiran, Reddy, Nishu January 2014 (has links)
This thesis is a part of collaborated project between Alstom and Blekinge Institute of Technology. In this thesis a fifth order non- linear Hamilton observer is applied on a series resonant converter. Two models for individual modes are given for a resonant power converter, one is suitable for simulation and other is suitable for simulation and analysis. The circuit is run in eight modes. A switched model of a fifth order DC/DC converter consisting of eight different switching modes has been derived and the performance of the circuit is studied under several conditions by simulation. / +917893357437
136

Telefonkataloghantering för mobila enheter

Svensson, Per-Erik, Skoglund, Sebastian January 2007 (has links)
The PhonePages of Sweden is a company that develops software for mobile units, especially cell phones. This thesis treats the development of, and contingencies for, a mobile phone directory, using the limited resources found in a mobile unit. The project was implemented and executed at The PhonePages with the intention of creating a product to sell to a third party. By studying different solutions, their benefits and drawbacks, an abstract picture of the product was constructed. Problems covered include compatibility problems caused by todays platform diversity as well as problems with saving, organizing and presenting data. The main goal was to create a phone directory which does not make external information retrievals. The service should contain both company and personal information, with name and phonenumber. Complete address information should also be available. The application should also manage different priorities and logotypes for the company information. The application, that emerged as a result of our work at The PhonePages, works independently, without making connections to the Internet and is completely implemented in J2ME, all according to the requirement specification. In other words, the analysis of the different solutions led to a working application.
137

Främling, vad döljer du för mig? : Skillnaden i personlighetsbedömningar av närstående och främlingar utifrån Facebook

Hanborg, Oskar, Selin, Martin January 2017 (has links)
Tidigare forskning har visat att vi drar slutsatser om andra personer redan utifrån ansikten och detta påverkar oss i många skeden i livet. Till viss del har även korrektheten av dessa bedömningar undersökts i olika situationer, t.ex. foto och/eller text utifrån arbetsansökningar och sociala medier. Ingen studie har undersökt hur väl vi kan bedöma andra individers personlighet beroende på relationsperspektiv och grad av information. Vi testade därför två hypoteser gällande Facebook; 1) Närstående bedömer bättre en individs personlighet än främlingar, oavsett informationsgrad, 2) Mer information kommer ge främlingarna en mer korrekt bedömning. För att besvara hypoteserna fick 90 deltagare skatta 15 deltagares personlighet utifrån tre olika relationsperspektiv; närstående, främling utifrån profilbild eller främling utifrån Facebookprofil. Samtliga deltagare rekryterades huvudsakligen från två lärosäten och genom bekvämlighetsurval. Resultatet gav stöd för första hypotesen men inte andra hypotesen. En närstående bedömer personlighet bättre än en främling och informationsgrad påverkar inte främlingars korrekthet signifikant. Dock kunde främlingar göra en bedömning som påvisade en bättre korrelation än noll. Detta menar vi har implikationer för främst rekryterare som ofta utgår från sociala medier i sin bedömning av arbetsansökande.
138

Assessing computed tomography image quality for combined detection and estimation tasks

Tseng, Hsin-Wu, Fan, Jiahua, Kupinski, Matthew A. 21 November 2017 (has links)
Maintaining or even improving image quality while lowering patient dose is always the desire in clinical computed tomography (CT) imaging. Iterative reconstruction (IR) algorithms have been designed to allow for a reduced dose while maintaining or even improving an image. However, we have previously shown that the dose-saving capabilities allowed with IR are different for different clinical tasks. The channelized scanning linear observer (CSLO) was applied to study clinical tasks that combine detection and estimation when assessing CT image data. The purpose of this work is to illustrate the importance of task complexity when assessing dose savings and to move toward more realistic tasks when performing these types of studies. Human-observer validation of these methods will take place in a future publication. Low-contrast objects embedded in body-size phantoms were imaged multiple times and reconstructed by filtered back projection (FBP) and an IR algorithm. The task was to detect, localize, and estimate the size and contrast of low-contrast objects in the phantom. Independent signal-present and signal-absent regions of interest cropped from images were channelized by the dense-difference of Gauss channels for CSLO training and testing. Estimation receiver operating characteristic (EROC) curves and the areas under EROC curves (EAUC) were calculated by CSLO as the figure of merit. The one-shot method was used to compute the variance of the EAUC values. Results suggest that the IR algorithm studied in this work could efficiently reduce the dose by similar to 50% while maintaining an image quality comparable to conventional FBP reconstruction warranting further investigation using real patient data. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
139

Ideální Bayesovský pozorovatel s redukovanou detekční mapou / Ideal Bayesian Observer with reduced detectability map

Amemori, Josef January 2016 (has links)
Title: Ideal Bayesian Observer with reduced detectability map Author: Josef Amemori Department: Department of Software and Computer Science Education Supervisor: Mgr. Filip Děchtěrenko, Department of Software and Computer Science Education Abstract: A computational modeling of the human vision is a challenging task. In recent years, a biologically inspired model Ideal Bayesian Observer was created for the visual search task (Najemnik & Geisler, 2005). The model predicts eye movements when searching for Gabor patch in 1/f noise. In their work, they observed similarity between distributions of fixations and saccades predicted by Ideal Bayesian Observer and distributions of fixations and saccades from a human observer. In this work, we have implemented Ideal Bayesian Observer with degenerated visual field and compared the model with behavior of a human. Keywords: Ideal Bayesian Observer, eye movements, modeling, central scotoma
140

Multi-agent System Distributed Sensor Fusion Algorithms

Bhattacharya, Shaondip January 2017 (has links)
The concept of consensus filters for sensor fusion is not an entirely new proposition but one with an internally implemented Bayesian fusion is. This work documents a novel state update algorithm for sensor fusion which works using the principle of Bayesian fusion of data with variance implemented on a single integrator consensus algorithm. Comparative demonstrations of how consensus over a pinning network is reached are presented along with a weighted Bayesian Luenberger type observer and a ’Consensus on estimates’ algorithm. This type of a filter is something that is novel and has not been encountered in previous literature related to this topic to the best of our knowledge. In this work, we also extend the proof for a distributed Luenberger type observer design to include the case where the network being considered is a strongly connected digraph.

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