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Quantificação do limiar de anaerobiose ventilatório no exercício físico dinâmico em cardiopatas chagásicos utilizando-se métodos visuais e computacionais; Quantification of anaerobic threshold during dynamic exercise in chagasic cardiac patients using visual and computerized methods.

Crescencio, Julio César
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/05/2007 PT
Relevância na Pesquisa
36.05%
Os avanços tecnológicos ocorridos na última década trouxeram enormes benefícios, no sentido de possibilitar o uso de equipamentos computadorizados, que permitem a aquisição, processamento e armazenamento de um grande número de variáveis respiratórias e metabólicas em exercício físico, em tempo real e a cada ciclo respiratório. Inserido neste novo cenário, o estudo realizado com esta nova geração de equipamentos, nas respectivas áreas de conhecimento, pôde ser direcionado, usando-se métodos matemáticos e estatísticos computadorizados, os quais possibilitam a aplicação de procedimentos automáticos e/ou semi-automáticos na solução de problemas específicos. É dentro deste contexto que se insere o presente estudo, que tem por objetivo estudar, em pacientes portadores de doença de Chagas e em indivíduos sadios, do sexo masculino, o limiar de anaerobiose ventilatório, durante o exercício físico dinâmico, realizado em cicloergômetro, usando-se métodos baseados em modelos matemáticos, automáticos e semi-automáticos, comparativamente com o método visual gráfico. Foram estudados 51 voluntários do sexo masculino, sendo 24 chagásicos e 27 saudáveis, a média de idade dos grupos chagásico e saudável foi de 33...

Variação entre observadores na aplicação dos critérios morfológicos e cinéticos propostos pelo BI-RADS® (Breast Imaging Reporting and Data System) para ressonância magnética das mamas; Observer variability in the application of morphologic and dynamic criteria according to the Breast Imaging Reporting and Data System for MRI

Moraes, Paula de Camargo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 04/04/2008 PT
Relevância na Pesquisa
26.31%
OBJETIVO. O objetivo deste estudo foi verificar a variação entre observadores, com diferentes graus de treinamento em RM das mamas, na aplicação dos critérios morfológicos e cinéticos propostos pelo BI-RADS® para descrever os realces na RM. Também, buscou-se avaliar a importância desta variação sobre a categorização final e a conduta sugerida, antes e após o conhecimento dos dados clínicos e dos demais exames de imagem pertinentes a cada caso. MÉTODOS. 109 realces, sendo 36 malignos, em 96 mulheres, foram interpretados por quatro radiologistas, divididos em duas duplas de acordo com a experiência em RM das mamas. Cada realce foi descrito seguindo os critérios de interpretação propostos pelo BI-RADS® para RM, sendo posteriormente informada a categoria final e a recomendação sugerida para cada caso. Tanto a categoria final quanto a conduta sugerida foram informadas duas vezes por cada observador, uma vez antes do conhecimento dos dados clínicos e dos demais exames de imagem e outra vez após o conhecimento dos mesmos. A concordância entre os membros de cada uma das duplas quanto à aplicação dos critérios de descrição morfológicos e dinâmicos utilizados na caracterização dos realces foi medida, seguida pela mensuração da concordância quanto à classificação final e a conduta recomendada...

Design of a state observer using decay rate LMI constraints for fault detection in mechanical systems

Koroishi, Edson Hideki; De Melo, Gilberto Pechoto; Assunção, Edvaldo
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 12-21
ENG
Relevância na Pesquisa
26.15%
Nowadays, one of the most important concerns for many companies is to maintain the operation of their systems without sudden equipment break down. Because of this, new techniques for fault detection and location in mechanical systems subject to dynamic loads have been developed. This paper studies of the influence of the decay rate in the design of state observers using LMI for fault detection in mechanical systems. This influence is analyzed by the performance index proposed by Huh and Stein for the condition of a state observer. An example is presented to illustrate the methodology discussed.

Diagnose de falhas via observadores de estado em sistemas mecânicos com absorvedores dinâmicos de vibrações tipo lâmina vibrante

Fernandes, Fernando Vitoriano
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Dissertação de Mestrado Formato: 167 f.
POR
Relevância na Pesquisa
26.15%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Pós-graduação em Engenharia Mecânica - FEIS; Neste trabalho foi desenvolvida uma metodologia de detecção e localização de falhas, para sistemas mecânicos que utilizam absorvedores dinâmicos de vibrações tipo lâmina vibrante (ADVLV). Através de modificações em alguns de seus parâmetros estruturais, o ADVLV desenvolvido absorve toda ou parte da vibração do sistema mecânico onde se encontra acoplado. Durante o trabalho foi utilizada a teoria de algoritmos genéticos baseada na evolução das espécies como ferramenta de otimização e em seguida, aplicou-se a metodologia de diagnóstico de falhas via observadores de estado para detecção e identificação de possíveis irregularidades no sistema. Na seqüência, a fim de validar a metodologia desenvolvida foram apresentados resultados obtidos através de simulações computacionais e experimentais, realizados com a construção de um ADVLV em uma estrutura primária pertencente ao laboratório de vibrações mecânicas do Departamento de Engenharia Mecânica da UNESP, Campus de Ilha Solteira.; In this work it was developed a technique of fault detection and location, to mechanical systems using dynamic vibration absorbers type blade vibrant (DVABV). Through changes in some of its structural parameters...

Observadores inteligentes de estado : propostas; Intelligent state observers : proposals

Cesar Daltoe Berci
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/07/2008 PT
Relevância na Pesquisa
36.41%
O problema de se observar o estado do sistema nasce da necessidade de se controlar plantas cujo estado não se pode medir. Convencionalmente são utilizados observadores baseados em modelos dinâmicos para resolver esse problema, através da construção de estimativas do estado desconhecido. Nesta tese, é abordada uma solução alternativa para este problema. Várias propostas de observadores inteligentes, são realizadas com base em mapeamentos entre subespaços gerados pelas equações que regem a dinâmica não linear do sistema, utilizando várias técnicas de inteligência computacional, capazes de apresentar estimativas do estado do sistema dinâmico através de observadores que não apresentam um comportamento dinâmico com relação ao tempo.; The state observer problem arises from the necessity of controlling plants whose state can not be measured. Usually dynamic model based observers are used to solve this problem, for estimating unknown state. In this thesis an alternative solution for this problem is presented. Various proposals for intelligent observers are made based on mappings between subspaces generated by the equations describing the nonlinear dynamics of the system, using various computational intelligence techniques able to present state estimates for the dynamic system through nonlinear observers that do not exhibit a dynamic behavior with respect to time.

Men Fear Other Men Most: Gender Specific Brain Activations in Perceiving Threat from Dynamic Faces and Bodies – An fMRI Study

Kret, Mariska Esther; Pichon, Swann; Grèzes, Julie; de Gelder, Beatrice
Fonte: Frontiers Research Foundation Publicador: Frontiers Research Foundation
Tipo: Artigo de Revista Científica
Publicado em 26/01/2011 EN
Relevância na Pesquisa
26.15%
Gender differences are an important factor regulating our daily interactions. Using functional magnetic resonance imaging we show that brain areas involved in processing social signals are activated differently by threatening signals send from male and female facial and bodily expressions and that their activation patterns are different for male and female observers. Male participants pay more attention to the female face as shown by increased amygdala activity. But a host of other areas show selective sensitivity for male observers attending to male threatening bodily expressions (extrastriate body area, superior temporal sulcus, fusiform gyrus, pre-supplementary motor area, and premotor cortex). This is the first study investigating gender differences in processing dynamic female and male facial and bodily expressions and it illustrates the importance of gender differences in affective communication.

Looking to Score: The Dissociation of Goal Influence on Eye Movement and Meta-Attentional Allocation in a Complex Dynamic Natural Scene

Taya, Shuichiro; Windridge, David; Osman, Magda
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 29/06/2012 EN
Relevância na Pesquisa
26.25%
Several studies have reported that task instructions influence eye-movement behavior during static image observation. In contrast, during dynamic scene observation we show that while the specificity of the goal of a task influences observers’ beliefs about where they look, the goal does not in turn influence eye-movement patterns. In our study observers watched short video clips of a single tennis match and were asked to make subjective judgments about the allocation of visual attention to the items presented in the clip (e.g., ball, players, court lines, and umpire). However, before attending to the clips, observers were either told to simply watch clips (non-specific goal), or they were told to watch the clips with a view to judging which of the two tennis players was awarded the point (specific goal). The results of subjective reports suggest that observers believed that they allocated their attention more to goal-related items (e.g. court lines) if they performed the goal-specific task. However, we did not find the effect of goal specificity on major eye-movement parameters (i.e., saccadic amplitudes, inter-saccadic intervals, and gaze coherence). We conclude that the specificity of a task goal can alter observer’s beliefs about their attention allocation strategy...

Dynamic Multiscale Boundary Conditions for 4D CT of Healthy and Emphysematous Rats

Jacob, Richard E.; Carson, James P.; Thomas, Mathew; Einstein, Daniel R.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 14/06/2013 EN
Relevância na Pesquisa
26.15%
Changes in the shape of the lung during breathing determine the movement of airways and alveoli, and thus impact airflow dynamics. Modeling airflow dynamics in health and disease is a key goal for predictive multiscale models of respiration. Past efforts to model changes in lung shape during breathing have measured shape at multiple breath-holds. However, breath-holds do not capture hysteretic differences between inspiration and expiration resulting from the additional energy required for inspiration. Alternatively, imaging dynamically – without breath-holds – allows measurement of hysteretic differences. In this study, we acquire multiple micro-CT images per breath (4DCT) in live rats, and from these images we develop, for the first time, dynamic volume maps. These maps show changes in local volume across the entire lung throughout the breathing cycle and accurately predict the global pressure-volume (PV) hysteresis. Male Sprague-Dawley rats were given either a full- or partial-lung dose of elastase or saline as a control. After three weeks, 4DCT images of the mechanically ventilated rats under anesthesia were acquired dynamically over the breathing cycle (11 time points, ≤100 ms temporal resolution, 8 cmH2O peak pressure). Non-rigid image registration was applied to determine the deformation gradient – a numerical description of changes to lung shape – at each time point. The registration accuracy was evaluated by landmark identification. Of 67 landmarks...

Suspiciousness perception in dynamic scenes: a comparison of CCTV operators and novices

Howard, Christina J.; Troscianko, Tom; Gilchrist, Iain D.; Behera, Ardhendu; Hogg, David C.
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 22/08/2013 EN
Relevância na Pesquisa
26.47%
Perception of scenes has typically been investigated by using static or simplified visual displays. How attention is used to perceive and evaluate dynamic, realistic scenes is more poorly understood, in part due to the problem of comparing eye fixations to moving stimuli across observers. When the task and stimulus is common across observers, consistent fixation location can indicate that that region has high goal-based relevance. Here we investigated these issues when an observer has a specific, and naturalistic, task: closed-circuit television (CCTV) monitoring. We concurrently recorded eye movements and ratings of perceived suspiciousness as different observers watched the same set of clips from real CCTV footage. Trained CCTV operators showed greater consistency in fixation location and greater consistency in suspiciousness judgements than untrained observers. Training appears to increase between-operators consistency by learning “knowing what to look for” in these scenes. We used a novel “Dynamic Area of Focus (DAF)” analysis to show that in CCTV monitoring there is a temporal relationship between eye movements and subsequent manual responses, as we have previously found for a sports video watching task. For trained CCTV operators and for untrained observers...

Depth Perception Not Found in Human Observers for Static or Dynamic Anti-Correlated Random Dot Stereograms

Hibbard, Paul B.; Scott-Brown, Kenneth C.; Haigh, Emma C.; Adrain, Melanie
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 08/01/2014 EN
Relevância na Pesquisa
26.35%
One of the greatest challenges in visual neuroscience is that of linking neural activity with perceptual experience. In the case of binocular depth perception, important insights have been achieved through comparing neural responses and the perception of depth, for carefully selected stimuli. One of the most important types of stimulus that has been used here is the anti-correlated random dot stereogram (ACRDS). In these stimuli, the contrast polarity of one half of a stereoscopic image is reversed. While neurons in cortical area V1 respond reliably to the binocular disparities in ACRDS, they do not create a sensation of depth. This discrepancy has been used to argue that depth perception must rely on neural activity elsewhere in the brain. Currently, the psychophysical results on which this argument rests are not clear-cut. While it is generally assumed that ACRDS do not support the perception of depth, some studies have reported that some people, some of the time, perceive depth in some types of these stimuli. Given the importance of these results for understanding the neural correlates of stereopsis, we studied depth perception in ACRDS using a large number of observers, in order to provide an unambiguous conclusion about the extent to which these stimuli support the perception of depth. We presented observers with random dot stereograms in which correlated dots were presented in a surrounding annulus and correlated or anti-correlated dots were presented in a central circular region. While observers could reliably report the depth of the central region for correlated stimuli...

Perceived glossiness in high dynamic range scenes

Doerschner, Katja; Maloney, Laurence T.; Boyaci, Huseyin
Fonte: Association for Research in Vision and Ophthalmology Publicador: Association for Research in Vision and Ophthalmology
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.31%
We investigated how spatial pattern, background, and dynamic range affect perceived gloss in brightly lit real scenes. Observers viewed spherical objects against uniform backgrounds. There were three possible objects. Two were black matte spheres with circular matte white dots painted on them (matte-dot spheres). The third sphere was painted glossy black (glossy black sphere). Backgrounds were either black or white matte, and observers saw each of the objects in turn on each background. Scenes were illuminated by an intense collimated source. On each trial, observers matched the apparent albedo of the sphere to an albedo reference scale and its apparent gloss to a gloss reference scale. We found that matte-dot spheres and the black glossy sphere were perceived as glossy on both backgrounds. All spheres were judged to be significantly glossier when in front of the black background. In contrast with previous research using conventional computer displays, we find that background markedly affects perceived gloss. This finding is surprising because darker surfaces are normally perceived as glossier (F. Pellacini, J. A. Ferwerda, & D. P. Greenberg, 2000). We conjecture that there are cues to surface material signaling glossiness present in high dynamic range scenes that are absent or weak in scenes presented using conventional computer displays.

Desenvolvimento do método de aquecimento plano parcial para a determinação simultânea de propriedades térmicas sem o uso de transdutores de fluxo de calor; Development of the Part Heat Plate Method to Estimate Simultaneously Thermal Properties without Heat Flux Transducer

Borges, Valério Luiz
Fonte: Universidade Federal de Uberlândia Publicador: Universidade Federal de Uberlândia
Tipo: Tese de Doutorado
POR
Relevância na Pesquisa
46.15%
Desenvolve-se, neste trabalho, uma técnica experimental que permite a obtenção da difusividade e da condutividade térmica de materiais condutores e não condutores através do uso de elementos de aquecimento e de técnicas de estimativas de funções para a obtenção do fluxo de calor imposto. O princípio básico do procedimento é dividido em: i) desenvolvimento de um aparato experimental que permite a imposição do fluxo de calor em uma parte da amostra enquanto as superfícies remanescentes permanecem isoladas do meio; ii) obtenção de um modelo térmico deste aparato; iii) obtenção de uma grandeza proporcional ao fluxo de calor imposto na amostra, Q+(t), usando a técnicas de problemas inversos; iv) obtenção da difusividade térmica; v) comparação entre a taxa de calor total fornecida pelo elemento de aquecimento e a grandeza proporcional ao fluxo de calor imposto na amostra durante o ciclo de aquecimento e a conseqüente obtenção da condutividade térmica. A flexibilidade da técnica proposta inclui a medição de materiais sólidos metálicos e não metálicos com geometrias variáveis. Nesse sentido, apresenta-se a montagem e o planejamento experimental bem como os resultados do trabalho para a determinação das propriedades térmicas de três tipos diferentes de materiais (aço inox 304...

Desenvolvimento de uma técnica baseada em funções de Green e observadores dinâmicos para aplicação em problemas inversos; Development of a technique based on Green’s functions and dynamic observers to be applied in inverse problems

Sousa, Priscila Ferreira Barbosa de
Fonte: Universidade Federal de Uberlândia Publicador: Universidade Federal de Uberlândia
Tipo: Dissertação
POR
Relevância na Pesquisa
56.25%
A maioria das técnicas usadas na solução de problemas inversos se restringe à solução de problemas unidimensionais, esbarrando em restrições computacionais e/ou matemáticas. Como alternativa na solução desse tipo de abordagem, técnicas de otimização e de filtros têm sido bastante usadas. A principal característica dos algoritmos que usam filtros é a robustez quanto à presença de ruídos experimentais, uma vez que essa interferência, que é inerente aos dados experimentais, pode ser amplificada durante o processo de estimação. A minimização dos efeitos do ruído é, portanto, fundamental na solução de problemas inversos. Neste sentido, esse trabalho apresenta um novo procedimento para o uso de observadores dinâmicos a ser aplicado na solução de problemas inversos multidimensionais em condução de calor. O novo procedimento consiste no uso de funções de Green e na definição de sistemas dinâmicos equivalentes para a obtenção da função de transferência de forma simples e direta. Tal procedimento pode ser usado indistintamente em modelos 1D, 2D ou 3D. Para avaliar a eficiência do uso da técnica baseada em funções de Green e observadores dinâmicos, testes simulados e experimentais foram realizados em modelos uni...

Dynamic State Estimation under Cyber Attacks: A Comparative Study of Kalman Filters and Observers

Taha, Ahmad F.; Qi, Junjian; Wang, Jianhui; Panchal, Jitesh H.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 28/08/2015
Relevância na Pesquisa
36.21%
Utilizing highly synchronized measurements from synchrophasors, dynamic state estimation (DSE) can be applied for real-time monitoring of smart grids. Concurrent DSE studies for power systems are intolerant to unknown inputs and potential attack vectors --- a research gap we will fill in this work. Particularly, we (a) present an overview of concurrent estimation techniques, highlighting key deficiencies, (b) develop DSE methods based on cubature Kalman filter and dynamic observers, (c) rigorously examine the strengths and weaknesses of the proposed methods under attack-vectors and unknown inputs, and (d) provide comprehensive recommendations for DSE. Numerical results and in-depth remarks are also presented.

Dynamic Observers for Fault Diagnosis of Timed Systems

Cassez, Franck
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 23/06/2010
Relevância na Pesquisa
36.21%
In this paper we extend the work on \emph{dynamic ob\-servers} for fault diagnosis to timed automata. We study sensor minimization problems with static observers and then address the problem of computing the most permissive dynamic observer for a system given by a timed automaton.

Fault Diagnosis with Dynamic Observers

Cassez, Franck; Tripakis, Stavros
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 16/04/2010
Relevância na Pesquisa
46.53%
In this paper, we review some recent results about the use of dynamic observers for fault diagnosis of discrete event systems. Fault diagnosis consists in synthesizing a diagnoser that observes a given plant and identifies faults in the plant as soon as possible after their occurrence. Existing literature on this problem has considered the case of fixed static observers, where the set of observable events is fixed and does not change during execution of the system. In this paper, we consider dynamic observers: an observer can "switch" sensors on or off, thus dynamically changing the set of events it wishes to observe. It is known that checking diagnosability (i.e., whether a given observer is capable of identifying faults) can be solved in polynomial time for static observers, and we show that the same is true for dynamic ones. We also solve the problem of dynamic observers' synthesis and prove that a most permissive observer can be computed in doubly exponential time, using a game-theoretic approach. We further investigate optimization problems for dynamic observers and define a notion of cost of an observer.; Comment: Extented version of the paper that appeared in Proc. of the 9th Workshop on Discrete Event Systems (WODES'08)

Pole placement design for quantum systems via coherent observers

Miao, Zibo; James, Matthew R.; Ugrinovskii, Valery A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 17/09/2015
Relevância na Pesquisa
26.19%
We previously extended Luenberger's approach for observer design to the quantum case, and developed a class of coherent observers which tracks linear quantum stochastic systems in the sense of mean values. In light of the fact that the Luenberger observer is commonly and successfully applied in classical control, it is interesting to investigate the role of coherent observers in quantum feedback. As the first step in exploring observer-based coherent control, in this paper we study pole-placement techniques for quantum systems using coherent observers, and in such a fashion, poles of a closed-loop quantum system can be relocated at any desired locations. In comparison to classical feedback control design incorporating the Luenberger observer, here direct coupling between a quantum plant and the observer-based controller are allowed to enable a greater degree of freedom for the design of controller parameters. A separation principle is presented, and we show how to design the observer and feedback independently to be consistent with the laws of quantum mechanics. The proposed scheme is applicable to coherent feedback control of quantum systems, especially when the transient dynamic response is of interest, and this issue is illustrated in an example.; Comment: 6 pages...

Rendering non-pictorial (Scientific) high dynamic range images

Park, Sung Ho
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.29%
In recent years, the graphics community is seeing an increasing demand for the capture and usage of high-dynamic-range (HDR) images. Since the production of HDR imagery is not solely the domain of the visualization of real life or computer generated scenes, novel techniques are also required for imagery captured from non-visual sources such as remote sensing, medical imaging, astronomical imaging, etc. This research proposes to integrate the techniques used for the display of high-dynamic-range pictorial imagery for the practical visualization of non-pictorial (scientific) imagery for data mining and interpretation. Nine algorithms were utilized to overcome the problem associated with rendering the high-dynamic-range image data to low-dynamic-range display devices, and the results were evaluated using a psychophysical experiment. Two paired-comparison experiments and a target detection experiment were performed. Paired-comparison results indicate that the Zone System performs the best on average and the Local Color Correction method performs the worst. The results show that the performance of different encoding schemes depend on the type of data being visualized. The correlation between the preference and scientific usefulness judgments (R2 = 0.31) demonstrates that observers tend to use different criteria when judging the scientific usefulness versus image preference. The experiment was conducted using observers with expertise (Radiologists) for the Medical image to further elucidate the success of HDR rendering on these data. The results indicated that both Radiologists and Non-radiologists tend to use similar criteria regardless of their experience and expertise when judging the usefulness of rendered images. A target detection experiment was conducted to measure the detectability of an embedded noise target in the Medical image to demonstrate the effect of the tone mapping operators on target detection. The result of the target detection experiment illustrated that the detectability of targets the image is greatly influenced by the rendering algorithm due to the inherent differences in tone mapping among the algorithms.

Evaluating tone mapping algorithms for rendering non-pictorial (scientific) high-dynamic-range images

Park, Sung Ho; Montag, Ethan
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Artigo de Revista Científica Formato: 2821486 bytes; application/pdf
EN_US
Relevância na Pesquisa
26.31%
Nine algorithms were implemented to overcome the problem associated with rendering highdynamic- range scientific imagery to low-dynamic-range display devices. The algorithms were evaluated using two paired-comparison psychophysical experiments judging preference and ”scientific usefulness”. The results showed that, on average, the Zone System algorithm performed best and the Local Color Correction method performed the worst. However, the performance of the algorithms depended on the type of data being visualized. The low correlation between the preference and scientific usefulness judgments (R2 = 0.31) indicated that observers used different criteria when judging the image preference versus scientific usefulness. The experiment was repeated using expert observers (radiologists) for an MR scan (Medical image). The results showed that the radiologists used similar criteria as the non-expert observers when judging the usefulness of the rendered images. A target detection experiment was conducted to measure the detectability of an embedded target in the Medical image. The result of the target detection experiment illustrated that the detectability of targets in the image is greatly influenced by the rendering algorithms due to the inherent difference in tone mapping among the algorithms.; Submitted to ACM: Transactions on Applied Perception (2006).; The authors are sincerely thankful to Garrett Johnson...

Fault Detection in a Heat Exchanger, Comparative Analysis between Dynamic Principal Component Analysis and Diagnostic Observers

Tudón Martínez,Juan C.; Morales Menéndez,Rubén; Ramírez Mendoza,Ricardo A.; Garza Castañón,Luis E.; Vargas Martínez,Adriana
Fonte: Centro de Investigación en computación, IPN Publicador: Centro de Investigación en computación, IPN
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2011 EN
Relevância na Pesquisa
36.31%
A comparison between the Dynamic Principal Component Analysis (DPCA) method and a set of Diagnostic Observers (DO) under the same experimental data from a shell and tube industrial heat exchanger is presented. The comparative analysis shows the detection properties of both methods when sensors and/or actuators fail online, including scenarios with multiple faults. Similar metrics are defined for both methods: robustness, quick detection, isolability capacity, explanation facility, false alarm rates and multiple faults identifiability. Experimental results show the principal advantages and disadvantages of both methods. DO showed quicker detection for sensor and actuator faults with lower false alarm rate. Also, DO can isolate multiple faults. DPCA required a minor training effort; however, it can not identify two or more sequential faults.