No description available.

We hypothesized that temporal features of EEG are altered in sleep apnea subjects comparedto normal subjects. The initial aim was to develop a measure to discriminate sleep stages innormals. The longer-term goal was to apply these methods to identify differences in EEGactivity in sleep apnea subjects from normals. We analyzed the C3A2 EEG and anelectrooculogram (EOG) recorded from 9 normal adults awake and in rapid eye movement(REM) and non-REM sleep. The EEG signals were filtered to remove EOG contamination. Twomeasures of the irregularity of EEG signals, Sample Entropy (SpEn) and Tsallis Entropy, wereevaluated for their ability to discriminate sleep stages. SpEn changes with sleep state, beinglargest in Wake. Stage 3/4 had the smallest SpEn (0.57??0.11) normalized to Wake values,followed by Stage 2 (0.72??0.09), REM (0.75??0.1) and Stage 1 (0.89??0.05). This pattern wasconsistent in all the polysomnogram records analyzed. Similar pattern was observed in leadO1A2 as well. We conclude that SpEn may be useful as part of a montage for assessing sleepstate. We analyzed data from sleep apnea subjects having obstructive and central apnea eventsand have made some preliminary observations; the SpEn values were more similar across sleepstages and also high correlation with oxygen saturation was observed.

No description available.

No / The use of electroencephalograms (EEGs) to diagnose and analyses Alzheimer's disease (AD) has received much attention in recent years. The sample entropy (SE) has been widely applied to the diagnosis of AD. In our study, nine EEGs from 21 scalp electrodes in 3 AD patients and 9 EEGs from 3 age-matched controls are recorded. The calculations show that the kurtoses of the AD patients' EEG are positive and much higher than that of the controls. This finding encourages us to introduce a kurtosis-based de-noising method. The 21-electrode EEG is first decomposed using independent component analysis (ICA), and second sort them using their kurtoses in ascending order. Finally, the subspace of EEG signal using back projection of only the last five components is reconstructed. SE will be calculated after the above de-noising preprocess. The classifications show that this method can significantly improve the accuracy of SE-based diagnosis. The kurtosis analysis of EEG may contribute to increasing the understanding of brain dysfunction in AD in a statistical way.

During vibration of engineering structures, fatigue cracks may exhibit repetitive crack open-close breathing like phenomenon. In this thesis, the concept of entropy is employed to quantify this bi-linearity/irregularity of the vibration response so as to evaluate crack severity. To increase the sensitivity of the entropy calculation to detect the damage severity, entropy is merged with wavelet transformation (WT). A cantilever beam with a breathing crack is studied to asses proposed crack identification method under two vibration conditions: sinusoidal and random excitations. Through numerical simulations and experimental testing, the breathing crack identification under sinusoidal excitation is studied first and proven to be effective. Then, the crack identification sensitivity under lower excitation frequencies is further improved by parametric optimization of sample entropy and WT. Finally, breathing crack identification under general random excitations are experimentally studied and realized using frequency response functions (FRFs) as an add-in tool with the proposed crack identification technique. / October 2016

Introdução: O objetivo desse estudo é obter um melhor entendimento de como o controle motor é afetado em indivíduos com polineuropatia diabética (PND). A oscilação da força e da atividade eletromiográfica (EMG) durante contrações voluntárias isométricas têm sido estudados como um modelo simplificado dos mecanismos fisiológicos que estão por trás do controle do movimento. A análise dos padrões de recrutamento muscular dos membros inferiores obtidos pela EMG de alta densidade, juntamente com a análise dos dados de força relativos às articulações do joelho e do tornozelo, sob a ótica da análise da complexidade, contribui para o entendimento dos efeitos da doença no controle dos movimentos. Além disso, analisar a complexidade da força e da atividade muscular de indivíduos diabéticos com PND levando em conta o progresso da severidade da doença, desde os estágios subclínicos aos mais avançados, irá ajudar no entendimento de como as alterações neuromusculares vão se instalando no curso da doença. As hipóteses desse estudo foram: a PND altera a complexidade motora o que se reflete em um aumento na magnitude da variabilidade e em uma diminuição da estrutura da variabilidade nos dados de força e EMG; e essas alterações pioram com a severidade da doença. Métodos: Foram avaliados 10 sujeitos controles e 38 sujeitos diabéticos, classificados como ausentes, leves, moderados ou graves, em relação ao nível da PND, por um sistema de tomada de decisão fuzzy cujas variáveis de entrada são clínicas. Foi adquirido o sinal EMG de alta densidade (matriz de 64 eletrodos) dos músculos tibial anterior, gastrocnêmio medial, vasto lateral e bíceps femoral durante a contração isométrica a 10%, 20% e 30% da contração voluntária máxima. Simultaneamente, foi adquirido o sinal da força isométrica durante a flexão e extensão de joelho e tornozelo. Foram calculados o desvio padrão e a sample entropy da força, e o root mean square e a sample entropy do EMG. As diferenças entre os grupos para as variáveis obtidas da força e do EMG foram verificadas através de análises multivariadas (alfa=0,05). Resultados: No geral, durante a flexão de tornozelo, sujeitos moderados e graves apresentaram um maior desvio padrão da força, e sujeitos moderados apresentaram menor sample entropy da força. Durante a extensão de tornozelo, os sujeitos moderados apresentaram maior desvio padrão da força e todos os grupos diabéticos apresentaram menor sample entropy da força. Durante a extensão do joelho, os sujeitos moderados apresentaram um maior desvio padrão e uma menor sample entropy da força. O tibial anterior apresentou um maior root mean square no grupo ausente e uma menor sample entropy nos sujeitos leves. O gastrocnêmio medial apresentou maior sample entropy nos sujeitos moderados e graves. Os sujeitos graves apresentaram menor sample entropy no vasto lateral em todos os níveis de força estudados. Conclusões: A PND afeta a complexidade do sistema neuromuscular durante contrações isométricas de baixa intensidade, reduzindo a capacidade do sistema de se adaptar às demandas mecânicas desafiadoras. Os padrões de complexidade neuromuscular observados não estavam associados à gravidade da doença, com a maioria das alterações sendo observadas no grupo moderado / Introduction: The general proposal of this study is to get a better understanding on how motor control is affected in diabetic polyneuropathy (DPN) individuals. Fluctuations of the force and sEMG signal during isometric voluntary contractions have been studied as a simplified model of the physiological mechanism that underlies the control of movement. The analysis of the muscular recruitment patterns from lower limbs, obtained by high-density sEMG, together with the corresponding force signal outputs from knee and ankle joints, in the light of complexity analysis, adds to the knowledge of the disease effects in motor control. Additionally, examining the complexity of force and muscle activity of DPN individuals, along with the development of DPN from subclinical to the more severe stages, will help us understanding how the alterations will develop with the DPN progression. The hypotheses of this study are that: DPN alters the motor complexity, expressed as an increased amount of variability and a decreased structure of variability in sEMG and force outputs, and these alterations are aggravated by the severity of the disease. Methods: We assessed 10 control subjects and 38 diabetic subjects, classified as absent, mild, moderate, or severe DPN, by a fuzzy-system based on clinical variables. Multichannel sEMG (64-electrode matrix) of tibialis anterior, gastrocnemius medialis, vastus lateralis and biceps femoris muscles were acquired during isometric contractions at 10%, 20%, and 30% of the maximum voluntary contraction, and force levels were recorded during dorsiflexion, plantarflexion, knee extension and knee flexion. Standard deviation and sample entropy of force signals were calculated and root mean square and sample entropy were calculated from sEMG signals. Differences among groups of force and sEMG variables were verified using a multivariate analysis of variance (alpha=0.05). Results: Overall, during dorsiflexion contractions, moderate and severe subjects had higher force standard deviation and moderate subjects had lower force sample entropy. During plantarflexion, moderate subjects had higher force standard deviation and all diabetic subjects had lower entropy. During knee extension moderate DPN subjects demonstrated high force standard deviation and low force sample entropy. Tibialis anterior presented higher root mean square in absent group and lower entropy in mild subjects. For gastrocnemius medialis, entropy was higher in severe and lower in moderate subjects. Severely affected participants showed low sample entropy in vastus lateralis at all force levels. Conclusions: DPN affects the complexity of the neuromuscular system during low-level isometric contractions, reducing the system\'s capacity to adapt to challenging mechanical demands. The observed patterns of neuromuscular complexity were not associated with disease severity, with the majority of alterations recorded in moderate subject

Introdução: O objetivo desse estudo é obter um melhor entendimento de como o controle motor é afetado em indivíduos com polineuropatia diabética (PND). A oscilação da força e da atividade eletromiográfica (EMG) durante contrações voluntárias isométricas têm sido estudados como um modelo simplificado dos mecanismos fisiológicos que estão por trás do controle do movimento. A análise dos padrões de recrutamento muscular dos membros inferiores obtidos pela EMG de alta densidade, juntamente com a análise dos dados de força relativos às articulações do joelho e do tornozelo, sob a ótica da análise da complexidade, contribui para o entendimento dos efeitos da doença no controle dos movimentos. Além disso, analisar a complexidade da força e da atividade muscular de indivíduos diabéticos com PND levando em conta o progresso da severidade da doença, desde os estágios subclínicos aos mais avançados, irá ajudar no entendimento de como as alterações neuromusculares vão se instalando no curso da doença. As hipóteses desse estudo foram: a PND altera a complexidade motora o que se reflete em um aumento na magnitude da variabilidade e em uma diminuição da estrutura da variabilidade nos dados de força e EMG; e essas alterações pioram com a severidade da doença. Métodos: Foram avaliados 10 sujeitos controles e 38 sujeitos diabéticos, classificados como ausentes, leves, moderados ou graves, em relação ao nível da PND, por um sistema de tomada de decisão fuzzy cujas variáveis de entrada são clínicas. Foi adquirido o sinal EMG de alta densidade (matriz de 64 eletrodos) dos músculos tibial anterior, gastrocnêmio medial, vasto lateral e bíceps femoral durante a contração isométrica a 10%, 20% e 30% da contração voluntária máxima. Simultaneamente, foi adquirido o sinal da força isométrica durante a flexão e extensão de joelho e tornozelo. Foram calculados o desvio padrão e a sample entropy da força, e o root mean square e a sample entropy do EMG. As diferenças entre os grupos para as variáveis obtidas da força e do EMG foram verificadas através de análises multivariadas (alfa=0,05). Resultados: No geral, durante a flexão de tornozelo, sujeitos moderados e graves apresentaram um maior desvio padrão da força, e sujeitos moderados apresentaram menor sample entropy da força. Durante a extensão de tornozelo, os sujeitos moderados apresentaram maior desvio padrão da força e todos os grupos diabéticos apresentaram menor sample entropy da força. Durante a extensão do joelho, os sujeitos moderados apresentaram um maior desvio padrão e uma menor sample entropy da força. O tibial anterior apresentou um maior root mean square no grupo ausente e uma menor sample entropy nos sujeitos leves. O gastrocnêmio medial apresentou maior sample entropy nos sujeitos moderados e graves. Os sujeitos graves apresentaram menor sample entropy no vasto lateral em todos os níveis de força estudados. Conclusões: A PND afeta a complexidade do sistema neuromuscular durante contrações isométricas de baixa intensidade, reduzindo a capacidade do sistema de se adaptar às demandas mecânicas desafiadoras. Os padrões de complexidade neuromuscular observados não estavam associados à gravidade da doença, com a maioria das alterações sendo observadas no grupo moderado / Introduction: The general proposal of this study is to get a better understanding on how motor control is affected in diabetic polyneuropathy (DPN) individuals. Fluctuations of the force and sEMG signal during isometric voluntary contractions have been studied as a simplified model of the physiological mechanism that underlies the control of movement. The analysis of the muscular recruitment patterns from lower limbs, obtained by high-density sEMG, together with the corresponding force signal outputs from knee and ankle joints, in the light of complexity analysis, adds to the knowledge of the disease effects in motor control. Additionally, examining the complexity of force and muscle activity of DPN individuals, along with the development of DPN from subclinical to the more severe stages, will help us understanding how the alterations will develop with the DPN progression. The hypotheses of this study are that: DPN alters the motor complexity, expressed as an increased amount of variability and a decreased structure of variability in sEMG and force outputs, and these alterations are aggravated by the severity of the disease. Methods: We assessed 10 control subjects and 38 diabetic subjects, classified as absent, mild, moderate, or severe DPN, by a fuzzy-system based on clinical variables. Multichannel sEMG (64-electrode matrix) of tibialis anterior, gastrocnemius medialis, vastus lateralis and biceps femoris muscles were acquired during isometric contractions at 10%, 20%, and 30% of the maximum voluntary contraction, and force levels were recorded during dorsiflexion, plantarflexion, knee extension and knee flexion. Standard deviation and sample entropy of force signals were calculated and root mean square and sample entropy were calculated from sEMG signals. Differences among groups of force and sEMG variables were verified using a multivariate analysis of variance (alpha=0.05). Results: Overall, during dorsiflexion contractions, moderate and severe subjects had higher force standard deviation and moderate subjects had lower force sample entropy. During plantarflexion, moderate subjects had higher force standard deviation and all diabetic subjects had lower entropy. During knee extension moderate DPN subjects demonstrated high force standard deviation and low force sample entropy. Tibialis anterior presented higher root mean square in absent group and lower entropy in mild subjects. For gastrocnemius medialis, entropy was higher in severe and lower in moderate subjects. Severely affected participants showed low sample entropy in vastus lateralis at all force levels. Conclusions: DPN affects the complexity of the neuromuscular system during low-level isometric contractions, reducing the system\'s capacity to adapt to challenging mechanical demands. The observed patterns of neuromuscular complexity were not associated with disease severity, with the majority of alterations recorded in moderate subject

The aging brain is characterized by alteration in synaptic contacts, which leads to decline of motor and cognitive functions. These changes are reflected in the age related shifts in power spectrum of electroencephalogram (EEG) signals in both wakefulness and sleep. Various non-linear measures have been used to obtain more insights from EEG analysis compared to the conventional spectral analysis. In our study we used Sample Entropy to quantify regularity of the EEG signal. Because elderly subjects arouse from sleep more often than younger subjects, we hypothesized that Entropy of EEG signals from elderly subjects would be higher than that from middle aged subjects, within a sleep stage. We also hypothesized that the entropy increases during and following an arousal and does not return to background levels immediately after an arousal. Our results show that Sample Entropy varies systematically with sleep state in healthy middle-aged and elderly female subjects, reflecting the changing regularity in the EEG. Sample Entropy is significantly higher in elderly in sleep Stage 2 and REM, suggesting that in these two sleep stages the cortical state is closer to wake than in middle-aged women. Sample Entropy is higher in post-arousal compared to the pre-arousal and stays high for a 30 sec period.

Master of Science / Industrial & Manufacturing Systems Engineering / Shing I. Chang / The process capability is a measurable property of a process related to the specification of a product. Traditionally, process capability analysis (PCA) measurements are expressed by a process capability ratio (PCR). When using a typical PCR to measure process capability, there are certain assumptions, and critics have been made towards PCR, that some the assumptions are violated. Much research has been conducted to ratify the situations when some of the assumptions are violated. This thesis, is going to demonstrate a research towards process capability using Sample Entropy method. The desirable outcome would be that this method can avoid violating the assumptions.

Submitted by Mario BC (mario@bc.ufrpe.br) on 2018-07-06T12:43:29Z No. of bitstreams: 1 Cleo Clayton Santos Silva.pdf: 1604461 bytes, checksum: 4c8c3bd59de5a0e36a2be10b43d2f89a (MD5) / Made available in DSpace on 2018-07-06T12:43:29Z (GMT). No. of bitstreams: 1 Cleo Clayton Santos Silva.pdf: 1604461 bytes, checksum: 4c8c3bd59de5a0e36a2be10b43d2f89a (MD5) Previous issue date: 2016-08-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Rainfall is one of the phases of the hydrological cycle responsible for the return of the condensed water from the atmosphere to the Earth's surface. It is a natural process of utmost importance for the functioning of ecosystems, because it regulates water availability for various uses and environmental services. Several studies have shown that climate change has significantly altered precipitation patterns in many parts of the globe. The present work aims to make an assessment of the rainfall time series in Pernambuco, Brazil, using monthly precipitation data for the period from 1950 to 2012, collected from the Meteorological Laboratory of Pernambuco State (LAMEP), division of the Technological Institute of Pernambuco (ITEP). Data were analyzed using the Sample Entropy method (SampEn) developed to quantify the complexity of nonlinear time series, and interpolated by Inverse Distance Weighting (IDW) method, providing an estimate of the complexity of the rainfall in the state of Pernambuco. The results shows that the higher values of entropy (greater complexity) concentrate in the Agreste and Atlantic Forest Zone, indicating that the rainfall dynamic is more regular in these regions than in other parts of the state. For all regions of Pernambuco, entropy values of monthly rainfall series are classified from moderate to low, indicating the feasibility of modeling of precipitation dynamics on monthly scale. / A precipitação pluviométrica é uma das fases do ciclo hidrológico responsáveis pelo retorno das águas condensadas na atmosfera à superfície terrestre. É um processo natural de extrema importância para o funcionamento dos ecossistemas, pois regula a disponibilidade hídrica para os diversos usos e serviços ambientais. Vários estudos tem demonstrado que as mudanças climáticas tem alterado significativamente os padrões de precipitação em várias partes do globo. O objetivo deste trabalho é avaliar a variabilidade de séries temporais de precipitação no Estado de Pernambuco através de dados mensais de precipitação datados durante o período de 1950 a 2012, cedidos pelo Laboratório de Meteorologia de Pernambuco (LAMEP), órgão pertencente ao Instituto Tecnológico de Pernambuco (ITEP). Os dados foram analisados através do método Sample Entropy (SampEn), desenvolvido para quantificar a complexidade em séries temporais não lineares, e interpolados através do método Inverse Distance Weighting (IDW), proporcionando uma estimativa da complexidade da precipitação no estado de Pernambuco. Os resultados mostraram que os maiores valores de entropia (maior complexidade) concentram-se no Agreste e Zona da Mata Pernambucana, indicando que a dinâmica da chuva é mais irregular nesta região do que no restante do estado. Para todo estado de Pernambuco, os valores de entropia das séries de precipitação mensal são classificados de moderado a baixo, indicando que ao longo de toda região, as séries não são difíceis de serem modeladas para realização de possíveis previsões da mesma na escala mensal.