Dissertations / Theses: 'Multiscale Entropy'

1

Granero, Belinchon Carlos. "Multiscale Information Transfer in Turbulence." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEN040/document.

Full text

Abstract:

Cette thèse est consacrée à l’étude statistique des systèmes complexes à travers l’analyse de signaux expérimentaux, de signaux synthétiques et de signaux générés à partir de modèles théoriques. On a choisi la turbulence comme paradigme d’ ́etude en raison de ses propriétés: dynamique non linéaire, comportement multi-échelle, cascade d’énergie, intermittence ... Afin de faire une caractérisation statistique d’un système complexe on s’intéresse à l’étude de la distribution (fonction de densité de probabilité), des corrélations et dépendances, et des relations de causalité de Wiener, des signaux qui décrivent le système. La théorie de l’information apparaît comme un cadre idéal pour developer ce type d’analyse. Dans le cadre de la théorie de l’information on a développé deux méthodologies, différentes mais reliées, pour analyser les propriétés d’auto similarité d’un système complexe, et plus précisément de la turbulence. La première méthodologie est basée sur l’analyse des incréments du processus étudié, avec l’entropie de Shannon et la divergence de Kullback-Leibler. La deuxième méthode, qui permet d’analyser des processus non stationnaires, est basée sur l’analyse du processus avec le taux d’entropie de Shannon. On a étudié la relation entre les deux méthodologies, lesquelles caractérisent la distribution d’information du système et la déformation de la distribution des incréments, à travers les échelles
Most of the time when studying a system, scientists face processes whose properties are a priori unknown. Characterising these processes is a major task to describe the studied system. During this thesis, which combines signal processing and physics, we were mainly motivated by the study of complex systems and turbulence, and consequently, we were interested in the study of regularity and self-similarity properties, long range dependence structures and multi-scale behavior. In order to perform this kind of study, we use information theory quantities, which are functions of the probability density function of the analysed process, and so depend on any order statistics of its PDF. We developed different, but related, data analysis methodologies, based on information theory, to analyse a process across scales τ. These scales are usually identified with the sampling parameter of Takens embedding procedure, but also with the size of the increments of the process. The methodologies developed during this thesis, can be used to characterize stationnary and non-stationnary processes by analysing time windows of length T of the studied signal

APA, Harvard, Vancouver, ISO, and other styles

2

Pires, Tiago Marques. "Quantificação da complexidade do ritmo cardíaco usando o método da Multiscale Entropy." Master's thesis, Faculdade de Ciências e Tecnologia, 2011. http://hdl.handle.net/10362/6630.

Full text

Abstract:

Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica
Uma forma de aumentar o nosso conhecimento sobre os princípios fundamentais de funcionamento dos sistemas de controlo biológicos é através da análise da dinâmica dos sinais por eles produzidos em condições normais, patológicas e em resposta a estímulos específicos. Porém, a maioria destes sinais desafiam as técnicas tradicionais de processamento de sinal devido a propriedades como a não estacionariedade, não linearidade, irreversibilidade e fractalidade/multi-fractalidade. Várias técnicas inovadoras para avaliar a dinâmica de sinais biológicos foram desenvolvidas na última década. Uma destas técnicas é designada multiscale entropy e quantifica o grau de complexidade de séries temporais. A hipótese subjacente ao trabalho apresentado nesta dissertação de tese de mestrado é a de que a complexidade da dinâmica dos sistemas biológicos se degrada com o envelhecimento e a doença, reflectindo perda de robustez, funcionalidade e capacidade de adaptação. Tal perda pode ocorrer a vários níveis de organização. Neste trabalho focamo-nos na quantificação da complexidade da dinâmica cardíaca de indivíduos normais, novos (50 anos) e mais velhos (>50 anos), e com diferentes graus de insuficiência cardíaca. Os sinais analisados são os dos intervalos de tempo entre batimentos cardíacos sucessivos derivados de registos electrocardiográficos de 24 horas (Holter). As dinâmicas cardíacas durante os períodos diurnos e nocturnos foram quantificadas independentemente. Os resultados anteriormente publicados mostraram que: i) a complexidade da dinâmica cardíaca é máxima para os indivíduos saudáveis e jovens, cujos mecanismos de controlo do ritmo cardíaco estão totalmente intactos; ii) a complexidade da dinâmica cardíaca degrada-se com a idade e ainda mais com a patologia cardíaca. A inovação do trabalho apresentado nesta dissertação reside numa nova implementação do método da multiscale entropy. A ideia subjacente ao método da multiscale entropy é a da quantificação da entropia de uma série temporal em múltiplas escalas de tempo. Vários algoritmos computacionais podem ser utilizados para calcular a entropia. Tanto neste trabalho como no da publicação original do método da multiscale entropy, o algoritmo usado para o cálculo da entropia é o designado sample entropy. Os valores da sample entropy são função de 3 parâmetros: N, m e r. N é o número total de pontos da série temporal; m é o número de componentes dos vectores que são necessários definir-se para o cálculo da sample entropy (tipicamente m = 2); r é um parâmetro usado para avaliar quando é que dois vectores são ou não indiscerníveis. Tipicamente r é igual a 15% do desvio padrão da série temporal. (Se a distância entre ui e uj é inferior ou igual a r, então os dois vectores são considerados indiscerníveis.) Neste trabalho, calculou-se a sample entropy usando um valor r fixo definido tendo por base a taxa de aquisição do electrocardiograma. Esta implementação conduziu a um aumento muito substancial da capacidade de diferenciar as dinâmicas cardíacas dos diferentes grupos de indivíduos.

APA, Harvard, Vancouver, ISO, and other styles

3

Silva, Luiz Eduardo Virgilio da. "Análise do sinal de variabilidade da frequência cardíaca através de estatística não extensiva: taxa de q-entropia multiescala." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-22032013-114045/.

Full text

Abstract:

O corpo humano é um sistema complexo composto por vários subsistemas interdependentes, que interagem entre si em várias escalas. Sabe-se que essa complexidade fisiológica tende a diminuir com a presença de doenças e com o avanço da idade, reduzindo a capacidade de adaptação dos indivíduos. No sistema cardiovascular, uma das maneira de se avaliar sua dinâmica regulatória é através da análise da variabilidade da frequência cardíaca (VFC). Os métodos clássicos de análise da VFC são baseados em modelos lineares, como é o caso da análise espectral. Contudo, como os mecanismos fisiológicos de regulação cardíaca apresentam características não lineares, as análises utilizando tais modelos podem ser limitadas. Nos últimos tempos, várias propostas de métodos não lineares têm surgido. Porém, não se sabe de uma medida consistente com o conceito de complexidade fisiológica, onde tanto os regimes periódicos como aleatórios são caracterizados como perda de complexidade. Baseado no conceito de complexidade fisiológica, esta tese propõe novos métodos de análise não lineares para séries de VFC. Os métodos consistem da generalização de medidas de entropia já existentes, utilizando a mecânica estatística não aditiva de Tsallis e a técnica de geração de dados substitutos. Foi definido um método, chamado de qSDiff, que calcula a diferença entre a entropia de um sinal e a entropia média de suas séries substitutas. O método de entropia utilizado consiste de uma generalização da entropia amostral (SampEn), utilizando o paradigma não aditivo. Das séries qSDiff foram extraídos três atributos, que foram avaliados como possíveis índices de complexidade fisiológica. A entropia multiescala (MSE) também foi generalizada seguindo o paradigma não aditivo, e os mesmos atributos foram calculados em várias escalas. Os métodos foram aplicados em séries reais de VFC de humanos e de ratos, bem como em um conjunto de sinais simulados, formado por ruídos e mapas, este último em regimes caótico e periódico. O atributo qSDiffmax demonstrou ser consistente para baixas escalas ao passo que os atributos qmax e qzero para escalas maiores, separando e classificando os grupos quanto à complexidade fisiológica. Observou-se ainda uma possível relação entre estes q-atributos com a presença de caos, que precisa ser melhor estudada. Os resultados ainda apontam a possibilidade de que, na insuficiência cardíaca, ocorre maior degradação nos mecanismos de baixa escala, de curto período, ao passo que na fibrilação atrial o prejuízo se estenderia para escalas maiores. As medidas baseadas em entropia propostas são capazes de extrair informações importantes das séries de VFC, sendo mais consistentes com o conceito de complexidade fisiológica do que a SampEn (clássica). Reforçou-se a hipótese de que a complexidade se revela em múltiplas escalas de um sinal. Acreditamos que os métodos propostos podem contribuir bastante na análise da VFC e também de outros sinais biomédicos.
Human body is a complex system composed of several interdependent subsystems, interacting at various scales. It is known that physiological complexity tends to decrease with disease and aging, reducing the adaptative capabilities of the individual. In the cardiovascular system, one way to evaluate its regulatory dynamics is through the analysis of heart rate variability (HRV). Classical methods of HRV analysis are based on linear models, such as spectral analysis. However, as the physiological mechanisms regulating heart rate exhibit nonlinear characteristics, analyzes using such models may be limited. In the last years, several proposals nonlinear methods have emerged. Nevertheless, no one is known to be consistent with the physiological complexity theory, where both periodic and random regimes are characterized as complexity loss. Based on physiological complexity theory, this thesis proposes new methods for nonlinear HRV series analysis. The methods are generalization of existing entropy measures, through Tsallis nonadditive statistical mechanics and surrogate data. We defined a method, called qSDiff, which calculates the difference between the entropy of a signal and its surrogate data average entropy. The entropy method used is a generalization of sample entropy (SampEn), through nonadditive paradigm. From qSDiff we extracted three attributes, which were evaluated as potential physiological complexity indexes. Multiscale entropy (MSE) was also generalized following nonadditive paradigm, and the same attributes were calculated at various scales. The methods were applied to real human and rats HRV series, as well as to a set of simulated signals, consisting of noises and maps, the latter in chaotic and periodic regimes. qSDiffmax attribute proved to be consistent for low scales while qmax and qzero attributes to larger scales, separating and ranking groups in terms of physiological complexity. There was also found a possible relationship between these q-attributes with the presence of chaos, which must be further investigated. The results also suggested the possibility that, in congestive heart failure, degradation occurs rather at small scales or short time mechanisms, while in atrial fibrillation, damage would extend to larger scales. The proposed entropy based measures are able to extract important information of HRV series, being more consistent with physiological complexity theory than SampEn (classical). Results strengthened the hypothesis that complexity is revealed at multiple scales. We believe that the proposed methods can contribute to HRV as well as to other biomedical signals analysis.

APA, Harvard, Vancouver, ISO, and other styles

4

Raikes, Adam C. "The Effects of Previous Concussions on the Physiological Complexity of Motor Output During a Continuous Isometric Visual-Motor Tracking Task." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/5803.

Full text

Abstract:

The majority of clinical impairments following a concussion resolve within 7-10 days. However, there is limited clarity as to long-term impact of this injury on neurocognitive function, motor control, and particularly integration of these domains. While repetitive head trauma is associated with numerous neurological disorders, the link is not well described. Visual-motor tracking tasks have been used to identify differences in visual processing, error detection, and fine motor control in aging and numerous pathologies. Examining the complexity of motor output from visual-motor tracking provides insight into multiple cognitive and motor function domains, and into fine motor control used for daily living, work, and sport. The purpose of this dissertation was, therefore, to: (1) use multiple regression to determine the extent to which concussion history and symptoms (loss of consciousness and amnesia) influence visual-motor task performance multiscale complexity, and (2) determine whether task performance complexity can distinguish, through logistic regression and prediction, between individuals with and without a history of concussion. In study 1, individuals with (n = 35) and without (n = 15) a history of concussion performed a visual-motor tracking task. Men and women exhibited linear decreases in task performance complexity, as well as midand high-frequency task performance components, with increasing numbers of concussions. However, men and women exhibited differing patterns, as did those with and without a history of concussion-related loss of consciousness. Finally, trial-to-trial complexity variability increased with increasing numbers of concussions. Findings indicate (1) a cumulative reduction in the way in which previously concussed individuals process and integrate visual information to guide behavior and (2) gender is an important consideration in concussion-related visual-motor outcomes. In Study 2, individuals with (n = 85) and without (n = 42) a history of concussion performed a visualmotor tracking task. Linear and nonlinear measures of task performance were used to build gender-specific logistic classification models using 10-fold cross-validation. When ensuring 80% sensitivity, the best models were 75-80% accurate in predicting a history of concussion. Such discrimination has clinical value in identifying individuals who merit further evaluation and observation over time for conditions related to repetitive head traumas.

APA, Harvard, Vancouver, ISO, and other styles

5

Li, Guanchen. "Non-equilibrium Thermodynamic Approach Based on the Steepest-Entropy-Ascent Framework Applicable across All Temporal and Spatial Scales." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/78354.

Full text

Abstract:

In this research, a first-principles, non-equilibrium thermodynamic-ensemble approach applicable across all temporal and spatial scales is developed based on steepest-entropy-ascent quantum thermodynamics (SEAQT). The SEAQT framework provides an equation of motion consisting of both reversible mechanical dynamics and irreversible relaxation dynamics, which is able to describe the evolution of any state of any system, equilibrium or non-equilibrium. Its key feature is that the irreversible dynamics is based on a gradient dynamics in system state space instead of the microscopic mechanics of more traditional approaches. System energy eigenstructure and density operator (or ensemble probability distribution) describe the system and system thermodynamic state, respectively. Extensive properties (i.e., energy, entropy, and particle number) play a key role in formulating the equation of motion and in describing non-equilibrium state evolutions. All the concepts involved in this framework (i.e., eigentstructure, density operator, and extensive properties) are well defined at all temporal and spatial scales leading to the extremely broad applicability of SEAQT. The focus of the present research is that of developing non-equilibrium thermodynamic models based specifically on the irreversible part of the equation of motion of SEAQT and applying these to the study of pure relaxation processes of systems in non-equilibrium states undergoing chemical reactions and heat and mass diffusion. As part of the theoretical investigation, the new concept of hypo-equilibrium state is introduced and developed. It is able to describe any non-equilibrium state going through a pure relaxation process and is a generalization of the concept of stable equilibrium of equilibrium thermodynamics to the non-equilibrium realm. Using the concept of hypo-equilibrium state, it is shown that non-equilibrium intensive properties can be fundamentally defined throughout the relaxation process. The definition of non-equilibrium intensive properties also relies on various ensemble descriptions of system state. In this research, three SEAQT ensemble descriptions, i.e., the canonical, grand canonical, and isothermal-isobaric, are derived corresponding, respectively, to the definition of temperature, chemical potential, and pressure. To computationally and not just theoretically permit the application of the SEAQT framework across all scales, a density of states method is developed, which is applicable to solving the SEAQT equation of motion for all types of non-equilibrium relaxation processes. In addition, a heterogeneous multiscale method (HMM) algorithm is also applied to extend the application of the SEAQT framework to multiscale modeling. Applications of this framework are given for systems involving chemical kinetics, the heat and mass diffusion of indistinguishable particles, power cycles, and the complex, coupled reaction-diffusion pathways of a solid oxide fuel cell (SOFC) cathode.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

6

Davalos, Trevino Antonio. "Sur les Propriétés Statistiques de l'Entropie de Permutation Multi-échelle et ses Raffinements; applications sur les Signaux Électromyographiques de Surface." Thesis, Orléans, 2020. http://www.theses.fr/2020ORLE3102.

Full text

Abstract:

L'entropie de permutation (EP) et l'entropie de permutation multi-échelle (EPM) sont largement utilisées dans l'analyse des séries temporelles à la recherche de régularités, notamment dans le contexte du signal biomédical. Les chercheurs doivent trouver des interprétations optimales, qui peuvent être compromises en ne prenant pas en compte les propriétés de l'algorithme MPE, notamment en ce qui concerne ses propriétés statistiques.C'est pourquoi, dans le présent travail, nous développons la théorie statistique qui sous-tend le MPE, notamment en ce qui concerne la caractérisation de ses deux premiers moments dans le contexte de la multi-échelle. Nous explorons ensuite les versions composites de MPE, afin de comprendre les propriétés sous-jacentes à l'amélioration de leurs performances. Nous avons également testé les valeurs attendues du MPE pour les processus stochastiques gaussiens largement utilisés, ce qui permet d'obtenir un repère d'entropie lorsque l'on utilise ces modèles pour simuler des signaux réels. Enfin, nous appliquons les méthodes MPE classique et composite sur des données électromyographiques de surface (sEMG), afin de différencier les différentes dynamiques d'activité musculaire dans les contractions isométriques.À la suite de notre projet, nous avons constaté que l'EPM est une statistique biaisée, qui diminue le respect du facteur multiéchelle indépendamment de la distribution de probabilité des signaux. Nous avons constaté que la variance de la statistique de l'EMM est fortement dépendante de la valeur de l'EMM elle-même, et presque égale à sa limite inférieure de Cramér-Rao, ce qui signifie que c'est un estimateur efficace. Nous avons constaté que les versions composites, bien qu'elles constituent une amélioration, mesurent également des informations réductrices, ce qui modifie l'estimation du PPE. En réponse, nous avons fourni un nouvel algorithme comme alternative à la multi-échelle à gros grains, ce qui améliore encore les estimations.Appliqué à des modèles gaussiens corrélés généraux, nous avons constaté que le MPE était entièrement caractérisé par les paramètres du modèle. Ainsi, nous avons développé une formulation générale de l'EMT attendue pour les dimensions d'encastrement faibles. Lorsque nous l'avons appliqué à des signaux sEMG réels, nous avons été en mesure de distinguer les états de fatigue et de non-fatigue avec toutes les méthodes, en particulier pour les dimensions d'encastrement élevées. En outre, nous avons constaté que la méthode de l'EMT que nous proposons permettait d'améliorer la différence entre les états d'activité.Par conséquent, nous fournissons au lecteur non seulement un développement sur la théorie actuelle du MPE, mais aussi les implications de ces résultats, à la fois dans le contexte de la modélisation et de l'application de ces techniques dans le domaine biomédical
Permutation Entropy (PE) and Multiscale Permutation Entropy (MPE) are extensively used in the analysis of time series searching for regularities, particularly in the context of biomedical signal. The researchers need to find optimal interpretations, which can be compromised by not taking in account the properties of the MPE algorithm, particularly regarding its statistical properties.Therefore, in the present work we expand on the statistical theory behind MPE, particularly regarding to the characterization of its first two moments in the context of multiscaling. We then explore the composite versions of MPE, in order to understand the underlying properties behind their improved performance. We also tested the expected MPE values for widely used Gaussian stochastic processes, which allows to obtain an Entropy benchmark when using these models to simulate real signals. Finally, we apply both the classical and composite MPE methods on surface Electromyographic (sEMG) data, in order to differentiate different muscle activity dynamics in isometric contractions.As a result of our project, we found the MPE to be a biased statistic, which decreases respect to the multiscaling factor regardless of the signals probability distribution. We found the MPE statistic’s variance to be highly dependent to the value of MPE itself, and almost equal to its Cramér-Rao Lower Bound, which means it is an efficient estimator. We found the composite versions, albeit an improvement, also measure reduntant information, which modifies the MPE estimation. In response, we provided a new algorithm as an alternative to the coarse-grain multiscaling, which further improve the estimations.When applied to general correlated Gaussian models, we found the MPE to be completely characterized by the model parameters. Thus, we developed a general formulation for the expected MPE for low embedding dimensions. When we applied to real sEMG signals, we were able to distinguish between fatigue and non-fatigue states with all methods, particularly for high embedding dimensions. Moreover, we found our proposed MPE method to enhance de difference between activity states.Therefore, we provide the reader with not only a development over the current MPE theory, but also with the implications of these findings, both in the context of modelization, and the application of these techniques in the biomedical field

APA, Harvard, Vancouver, ISO, and other styles

7

Uffreduzzi, Alessio. "Strumentazione mediante sensori inerziali di test per la valutazione delle funzioni visuo-spaziali costruttive in età evolutiva: uno studio preliminare." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2017.

Find full text

Abstract:

L’obiettivo di questa tesi è quello di indagare la possibilità di strumentare mediante sensori inerziali indossabili alcuni test per la valutazione delle competenze visuo-costruttive: “Salvadanaio” (Posting Coins), “Invertire i pioli” (Turning Pegs) e “Laccio” (Threading Lace) della batteria Movement ABC. A tal fine si è valutata la possibilità di utilizzare parametri quantitativi utilizzati in analisi del movimento per la caratterizzazione della performance dell’arto superiore durante compiti che richiedono appunto abilità visuo-costruttive. Hanno preso parte allo studio undici soggetti adulti giovani sani e quattro bambini con sviluppo tipico. Dopo aver posizionato i sensori inerziali sui polsi è stato richiesto ai soggetti di svolgere i test sopraelencati come da manuale di riferimento. Da questo studio preliminare, i parametri che sono risultati più rilevanti per la caratterizzazione delle abilità visuo-costruttive sono stati la complessità (misurata con la Multiscale Entropy) e la frequenza mediana, stimate sul segnale accelerometrico dell’arto che eseguiva l’esercizio. Questi parametri hanno mostrato, come atteso, un trend diverso tra soggetti adulti e quelli in età evolutiva. I risultati di questo studio potranno essere utilizzati come base di partenza per ulteriori sviluppi futuri.

APA, Harvard, Vancouver, ISO, and other styles

8

SILVA, José Rodrigo Santos. "Avaliação de autocorrelações e complexidade de séries temporais climáticas no Brasil." Universidade Federal Rural de Pernambuco, 2014. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/5009.

Full text

Abstract:

Submitted by (ana.araujo@ufrpe.br) on 2016-07-07T11:52:38Z No. of bitstreams: 1 Jose Rodrigo Santos Silva.pdf: 13129069 bytes, checksum: b427ff42ec7918c3d0cf7f63798ed648 (MD5)
Made available in DSpace on 2016-07-07T11:52:38Z (GMT). No. of bitstreams: 1 Jose Rodrigo Santos Silva.pdf: 13129069 bytes, checksum: b427ff42ec7918c3d0cf7f63798ed648 (MD5) Previous issue date: 2014-09-19
The objective of this study was to uncloak the dynamic of climate of Brazil, seeking to measure the regularity and the long range autocorrelation of daily climate series of temperature of air (average, maximum, minimum, and temperature range), relative humidity of air average and wind speed average. The data were obtained by Instituto Nacional de Meteorologia (INMET), at 264 meteorological stations, in the period from January 1990 to December 2012. We use the Detrended Fluctuation Analysis to realize the estimation of the Hurst exponent, the Multiscale Sample Entropy to estimating the entropy of series and the Kriging to interpolate the estimates made. We observed that higher latitudes tend to attenuate the mean of temperatures of air maximum, minimum and average, but increase the variability of the same. This inversion of the magnitudes of the mean and standard deviation is also observed in the relative humidity of air. The means of the estimated Hurst exponents estimated for Brazil were 0.81, 0.79, 0.81, 0.77, 0.83 and 0.64, and the estimated Sample Entropy, 1.39, 1.78, 1.46, 1.41, 1.56 and 1.66, respectively for average, maximum and minimum temperatures of air, temperature range, relative humidity of air average and wind speed average. The values of the estimated Hurst exponents showed a positive correlation with latitude in the temperature variables studied. Such a correlation was not observed in other variables. This a correlation was not observed in other variables. The regularities of climate series in Brazil were medians. Spatially, the greatest changes occurred in estimates of entropies in the scale 1 to 2 of , in the Multiscale Sample Entropy. As from ≥2 the changes observed were more subtle. We observe the influence of the Equatorial Continental air mass in entropy of temperatures daily average and maximum of air. The climatic factor of altitude influenced with more frequently in the observed results, mainly on temperature variables. In some cases, the continentality and the air masses were also identified as important factors in characterizing the spatial distribution of estimates made.
O objetivo deste estudo foi desvendar a dinâmica climática do Brasil, buscando mensurar a regularidade e a autocorrelação de longo alcance em séries climáticas diárias de temperatura do ar (média, máxima, mínima, e amplitude térmica), umidade relativa média do ar e velocidade média diária do vento. Os dados foram obtidos pelo Instituto Nacional de Meteorologia, em 264 estações meteorológicas, no período de janeiro de 1990 a dezembro de 2012. Utilizamos o Detrended Fluctuation Analysis para realizar a estimativa do expoente de Hurst, o Multiscale Sample Entropy para as estimativas da entropia das séries e o Kriging para a interpolação das estimativas realizadas. Observamos que maiores latitudes tendem a atenuar as médias das temperaturas máxima, mínima e média do ar, porém aumentam a variabilidade das mesmas. Esta inversão entre as magnitudes da média e do desvio padrão também é observado na umidade relativa média do ar. As médias dos expoentes de Hurst estimados para todo o Brasil foram 0,81; 0,79; 0,81; 0,77; 0,83 e 0,64; e do Sample Entropy estimado, 1,39; 1,78; 1,46; 1,41; 1,56 e 1,66, respectivamente para séries diárias de temperatura média, máxima e mínima do ar, amplitude térmica do ar, umidade relativa média do ar e velocidade média do vento. Os valores do expoentes de Hurst estimados apresentaram uma correlação positiva com a latitude nas variáveis de temperatura do ar estudadas. Tal correlação não foi observada nas demais variáveis. As regularidades das séries climáticas no Brasil foram medianas. Espacialmente, as maiores alterações nas estimativas das entropias ocorreram na escala 1 para a 2 de , no Multiscale Sample Entropy. A partir de ≥2 as mudanças observadas foram mais sutis. Observamos influência da massa de ar Equatorial Continental na entropia das temperaturas do ar média e máxima diárias. O fator climático da altitude atuou com maior frequência sob os resultados observados, principalmente nas variáveis de temperatura. Em alguns casos, a continentalidade e as massas de ar também foram apontados como fatores importantes na caracterização da distribuição espacial das estimativas realizadas.

APA, Harvard, Vancouver, ISO, and other styles

9

Blons, Estelle. "Dynamiques individuelles et collectives de la complexité de signaux physiologiques en situation de stress induit." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0152.

Full text

Abstract:

Les études récentes en santé humaine supposent un lien de causalité entre la complexité des systèmes de contrôle psychophysiologique et la complexité des biosignaux qu’ils émettent. Le travail mené dans le cadre de cette thèse illustre ce principe en s’appuyant sur une démarche interdisciplinaire, combinant physiologie, psychologie et traitement du signal. Il vise à étudier les dynamiques des signaux physiologiques émis par l’Homme, en réponse à un stress induit en situation individuelle ou collective. Le stress étant un processus multifactoriel qui dépend de la perception et de l’interprétation d’une situation donnée par un individu, l’étude des signaux physiologiques est combinée à l’évaluation de caractéristiques psychologiques contextuelles et dispositionnelles. En particulier, nous nous intéressons aux régulations cardiaques qui sont analysées à partir des séries temporelles définies par les durées successives des intervalles RR. Des approches statistiques temporelles, fréquentielles ou non-linéaires sont utilisées afin d’étudier les capacités d’adaptation des individus confrontés à différentes situations de tâches cognitives associées ou non à des facteurs stressants. Il s’agit d’extraire des signatures caractéristiques des régulations centrales et autonomes, au repos ou dans différentes situations expérimentales. Dans ce travail, un intérêt particulier est accordé à l’entropie multi-échelles afin d’évaluer la complexité des signaux, une complexité induite par les interconnexions existant entre structures corticales, sous-corticales et régulations autonomes cardiaques. Nous proposons également d’analyser les signaux collectés durant les différentes situations expérimentales, en comparant deux à deux leurs densités de probabilité à partir de la divergence de Kullback-Leibler, et en particulier d’une estimation de l'incrément asymptotique de la divergence de Kullback-Leibler. Les résultats obtenus mettent en évidence que l’étude des signaux cardiaques peut permettre d’appréhender l’état psychophysiologique d’un individu lorsqu’il est confronté à des situations de tâches cognitives et de stress. Des différences d’états apparaissent non seulement à l’échelle individuelle, mais également à l’échelle collective, lorsque l’individu n’est pas directement confronté aux stimuli stressants mais que le stress est de nature empathique. Enfin, deux applications sont réalisées. Nous montrons que la complexité des signaux cardiaques, altérée chez des personnes stressées au travail, peut être améliorée par un entraînement à la cohérence cardiaque. Nous appliquons également les méthodes de traitement du signal à l’étude de la régulation posturale. L’ensemble de nos résultats renforcent l’intérêt du monitoring de l’humain en matière de santé
Recent studies in human health assume a causal link between the complexity of psychophysiological control systems and the complexity of their resulting biosignals. This PhD illustrates the aforementioned principle by relying on an interdisciplinary approach, combining physiology, psychology and signal processing. The dynamics of human output physiological signals are studied in response to induced stress in individual or collective situations. The objective is to extract individual signatures depicting the central and autonomic regulations at rest or in different experimental situations. Since stress is a multifactorial process depending on the individual perception and interpretation of a situation, the study of physiological signals is combined with the evaluation of psychological contextual and dispositional characteristics. We focus our attention on cardiac regulations which are analysed from the time series defined by the successive durations of the RR intervals. Statistical signal processing methods, either temporal, frequency or non-linear, are used to study the adaptive capacities of individuals facing different situations of cognitive tasks associated or not with stressors. A particular interest is given to multiscale entropy to assess the complexity of signals, which makes it possible to consider the interconnections existing between cortical, subcortical structures and autonomic cardiac regulations. The probability density functions of recorded cardiac signals along each different experimental situation are compared two by two by using the Kullback-Leibler divergence, and in particular the estimate of the asymptotic increment of the divergence of Kullback-Leibler. The results show that studying cardiac signals allows to discriminate the psychophysiological state of an individual when facing either cognitive tasks or stressful situations. Psychophysiological state differences emerge during stress, not only at an individual level, but also at a collective one, for which the subject is not directly confronted with stressful stimuli. The stress is therefore empathic. Two experimental applications are carried out from our results. First, we show that the cardiac complexity, which is altered in people stressed at work, can be improved by cardiac coherence biofeedback training. Second, signal processing methods are also used to the study of postural regulation. Overall, our results strengthen the interest of human monitoring in health

APA, Harvard, Vancouver, ISO, and other styles

10

Zhang, Tianyu. "Problème inverse statistique multi-échelle pour l'identification des champs aléatoires de propriétés élastiques." Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC2068.

Full text

Abstract:

Dans le cadre de la théorie de l'élasticité linéaire, la modélisation et simulation numérique du comportement mécanique des matériaux hétérogènes à microstructure aléatoire complexe soulèvent de nombreux défis scientifiques à différentes échelles. Bien qu'à l'échelle macroscopique, ces matériaux soient souvent modélisés comme des milieux homogènes et déterministes, ils sont non seulement hétérogènes et aléatoires à l'échelle microscopique, mais ils ne peuvent généralement pas non plus être explicitement décrits par les propriétés morphologiques et mécaniques locales de leurs constituants. Par conséquent, une échelle mésoscopique est introduite entre l'échelle macroscopique et l'échelle mésoscopique, pour laquelle les propriétés mécaniques d'un tel milieu élastique linéaire aléatoire sont décrites par un modèle stochastique prior non-gaussien paramétré par un nombre faible ou modéré d'hyperparamètres inconnus. Afin d'identifier ces hyperparamètres, une méthodologie innovante a été récemment proposée en résolvant un problème statistique inverse multi-échelle en utilisant uniquement des données expérimentales partielles et limitées aux deux échelles macroscopique et mésoscopique. Celui-ci a été formulé comme un problème d'optimisation multi-objectif qui consiste à minimiser une fonction-coût multi-objectif (à valeurs vectorielles) définie par trois indicateurs numériques correspondant à des fonctions-coût mono-objectif (à valeurs scalaires) permettant de quantifier et minimiser des distances entre les données expérimentales multi-échelles mesurées simultanément aux deux échelles macroscopique et mésoscopique sur un seul échantillon soumis à un essai statique, et les solutions des modèles numériques déterministe et stochastique utilisés pour simuler la configuration expérimentale multi-échelle sous incertitudes. Ce travail de recherche vise à contribuer à l'amélioration de la méthodologie d'identification inverse statistique multi-échelle en terme de coût de calcul, de précision et de robustesse en introduisant (i) une fonction-coût mono-objectif (indicateur numérique) supplémentaire à l'échelle mésoscopique quantifiant la distance entre la(les) longueur(s) de corrélation spatiale des champs expérimentaux mesurés et celle(s) des champs numériques calculés, afin que chaque hyperparamètre du modèle stochastique prior ait sa propre fonction-coût mono-objectif dédiée, permettant ainsi d'éviter d'avoir recours à l'algorithme d'optimisation global (algorithme génétique) utilisé précédemment et de le remplacer par un algorithme plus performant en terme d'efficacité numérique, tel qu'un algorithme itératif de type point fixe, pour résoudre le problème d'optimisation multi-objectif avec un coût de calcul plus faible, et (ii) une représentation stochastique ad hoc des hyperparamètres impliqués dans le modèle stochastique prior du champ d'élasticité aléatoire à l'échelle mésoscopique en les modélisant comme des variables aléatoires, pour lesquelles les distributions de probabilité peuvent être construites en utilisant le principe du maximum d'entropie sous un ensemble de contraintes définies par les informations objectives et disponibles, et dont les hyperparamètres peuvent être déterminés à l'aide de la méthode d'estimation du maximum de vraisemblance avec les données disponibles, afin d'améliorer à la fois la robustesse et la précision de la méthode d'identification inverse du modèle stochastique prior. En parallèle, nous proposons également de résoudre le problème d'optimisation multi-objectif en utilisant l’apprentissage automatique par des réseaux de neurones artificiels. Finalement, la méthodologie améliorée est tout d'abord validée sur un matériau virtuel fictif dans le cadre de l'élasticité linéaire en 2D contraintes planes et 3D, puis illustrée sur un matériau biologique hétérogène réel (os cortical de bœuf) en élasticité linéaire 2D contraintes planes
Within the framework of linear elasticity theory, the numerical modeling and simulation of the mechanical behavior of heterogeneous materials with complex random microstructure give rise to many scientific challenges at different scales. Despite that at macroscale such materials are usually modeled as homogeneous and deterministic elastic media, they are not only heterogeneous and random at microscale, but they often also cannot be properly described by the local morphological and mechanical properties of their constituents. Consequently, a mesoscale is introduced between macroscale and microscale, for which the mechanical properties of such a random linear elastic medium are represented by a prior non-Gaussian stochastic model parameterized by a small or moderate number of unknown hyperparameters. In order to identify these hyperparameters, an innovative methodology has been recently proposed by solving a multiscale statistical inverse problem using only partial and limited experimental data at both macroscale and mesoscale. It has been formulated as a multi-objective optimization problem which consists in minimizing a (vector-valued) multi-objective cost function defined by three numerical indicators corresponding to (scalar-valued) single-objective cost functions for quantifying and minimizing distances between multiscale experimental data measured simultaneously at both macroscale and mesoscale on a single specimen subjected to a static test, and the numerical solutions of deterministic and stochastic computational models used for simulating the multiscale experimental test configuration under uncertainties. This research work aims at contributing to the improvement of the multiscale statistical inverse identification method in terms of computational efficiency, accuracy and robustness by introducing (i) an additional mesoscopic numerical indicator allowing the distance between the spatial correlation length(s) of the measured experimental fields and the one(s) of the computed numerical fields to be quantified at mesoscale, so that each hyperparameter of the prior stochastic model has its own dedicated single-objective cost-function, thus allowing the time-consuming global optimization algorithm (genetic algorithm) to be avoided and replaced with a more efficient algorithm, such as the fixed-point iterative algorithm, for solving the underlying multi-objective optimization problem with a lower computational cost, and (ii) an ad hoc stochastic representation of the hyperparameters involved in the prior stochastic model of the random elasticity field at mesoscale by modeling them as random variables, for which the probability distributions can be constructed by using the maximum entropy principle under a set of constraints defined by the available and objective information, and whose hyperparameters can be determined using the maximum likelihood estimation method with the available data, in order to enhance both the robustness and accuracy of the statistical inverse identification method of the prior stochastic model. Meanwhile, we propose as well to solve the multi-objective optimization problem by using machine learning based on artificial neural networks. Finally, the improved methodology is first validated on a fictitious virtual material within the framework of 2D plane stress and 3D linear elasticity theory, and then illustrated on a real heterogenous biological material (beef cortical bone) in 2D plane stress linear elasticity

APA, Harvard, Vancouver, ISO, and other styles

11

Rasquin, Michel. "Numerical tools for the large eddy simulation of incompressible turbulent flows and application to flows over re-entry capsules." Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210118.

Full text

Abstract:

The context of this thesis is the numerical simulation of turbulent flows at moderate Reynolds numbers and the improvement of the capabilities of an in-house 3D unsteady and incompressible flow solver called SFELES to simulate such flows.

In addition to this abstract, this thesis includes five other chapters.

The second chapter of this thesis presents the numerical methods implemented in the two CFD solvers used as part of this work, namely SFELES and PHASTA.

The third chapter concentrates on the implementation of a new library called FlexMG. This library allows the use of various types of iterative solvers preconditioned by algebraic multigrid methods, which require much less memory to solve linear systems than a direct sparse LU solver available in SFELES. Multigrid is an iterative procedure that relies on a series of increasingly coarser approximations of the original 'fine' problem. The underlying concept is the following: low wavenumber errors on fine grids become high wavenumber errors on coarser levels, which can be effectively removed by applying fixed-point methods on coarser levels.

Two families of algebraic multigrid preconditioners have been implemented in FlexMG, namely smooth aggregation-type and non-nested finite element-type. Unlike pure gridless multigrid, both of these families use the information contained in the initial fine mesh. A hierarchy of coarse meshes is also needed for the non-nested finite element-type multigrid so that our approaches can be considered as hybrid. Our aggregation-type multigrid is smoothed with either a constant or a linear least square fitting function, whereas the non-nested finite element-type multigrid is already smooth by construction. All these multigrid preconditioners are tested as stand-alone solvers or coupled with a GMRES (Generalized Minimal RESidual) method. After analyzing the accuracy of the solutions obtained with our solvers on a typical test case in fluid mechanics (unsteady flow past a circular cylinder at low Reynolds number), their performance in terms of convergence rate, computational speed and memory consumption is compared with the performance of a direct sparse LU solver as a reference. Finally, the importance of using smooth interpolation operators is also underlined in this work.

The fourth chapter is devoted to the study of subgrid scale models for the large eddy simulation (LES) of turbulent flows.

It is well known that turbulence features a cascade process by which kinetic energy is transferred from the large turbulent scales to the smaller ones. Below a certain size, the smallest structures are dissipated into heat because of the effect of the viscous term in the Navier-Stokes equations.

In the classical formulation of LES models, all the resolved scales are used to model the contribution of the unresolved scales. However, most of the energy exchanges between scales are local, which means that the energy of the unresolved scales derives mainly from the energy of the small resolved scales.

In this fourth chapter, constant-coefficient-based Smagorinsky and WALE models are considered under different formulations. This includes a classical version of both the Smagorinsky and WALE models and several scale-separation formulations, where the resolved velocity field is filtered in order to separate the small turbulent scales from the large ones. From this separation of turbulent scales, the strain rate tensor and/or the eddy viscosity of the subgrid scale model is computed from the small resolved scales only. One important advantage of these scale-separation models is that the dissipation they introduce through their subgrid scale stress tensor is better controlled compared to their classical version, where all the scales are taken into account without any filtering. More precisely, the filtering operator (based on a top hat filter in this work) allows the decomposition u' = u - ubar, where u is the resolved velocity field (large and small resolved scales), ubar is the filtered velocity field (large resolved scales) and u' is the small resolved scales field.

At last, two variational multiscale (VMS) methods are also considered.

The philosophy of the variational multiscale methods differs significantly from the philosophy of the scale-separation models. Concretely, the discrete Navier-Stokes equations have to be projected into two disjoint spaces so that a set of equations characterizes the evolution of the large resolved scales of the flow, whereas another set governs the small resolved scales.

Once the Navier-Stokes equations have been projected into these two spaces associated with the large and small scales respectively, the variational multiscale method consists in adding an eddy viscosity model to the small scales equations only, leaving the large scales equations unchanged. This projection is obvious in the case of a full spectral discretization of the Navier-Stokes equations, where the evolution of the large and small scales is governed by the equations associated with the low and high wavenumber modes respectively. This projection is more complex to achieve in the context of a finite element discretization.

For that purpose, two variational multiscale concepts are examined in this work.

The first projector is based on the construction of aggregates, whereas the second projector relies on the implementation of hierarchical linear basis functions.

In order to gain some experience in the field of LES modeling, some of the above-mentioned models were implemented first in another code called PHASTA and presented along with SFELES in the second chapter.

Finally, the relevance of our models is assessed with the large eddy simulation of a fully developed turbulent channel flow at a low Reynolds number under statistical equilibrium. In addition to the analysis of the mean eddy viscosity computed for all our LES models, comparisons in terms of shear stress, root mean square velocity fluctuation and mean velocity are performed with a fully resolved direct numerical simulation as a reference.

The fifth chapter of the thesis focuses on the numerical simulation of the 3D turbulent flow over a re-entry Apollo-type capsule at low speed with SFELES. The Reynolds number based on the heat shield is set to Re=10^4 and the angle of attack is set to 180º, that is the heat shield facing the free stream. Only the final stage of the flight is considered in this work, before the splashdown or the landing, so that the incompressibility hypothesis in SFELES is still valid.

Two LES models are considered in this chapter, namely a classical and a scale-separation version of the WALE model. Although the capsule geometry is axisymmetric, the flow field in its wake is not and induces unsteady forces and moments acting on the capsule. The characterization of the phenomena occurring in the wake of the capsule and the determination of their main frequencies are essential to ensure the static and dynamic stability during the final stage of the flight.

Visualizations by means of 3D isosurfaces and 2D slices of the Q-criterion and the vorticity field confirm the presence of a large meandering recirculation zone characterized by a low Strouhal number, that is St≈0.15.

Due to the detachment of the flow at the shoulder of the capsule, a resulting annular shear layer appears. This shear layer is then affected by some Kelvin-Helmholtz instabilities and ends up rolling up, leading to the formation of vortex rings characterized by a high frequency. This vortex shedding depends on the Reynolds number so that a Strouhal number St≈3 is detected at Re=10^4.

Finally, the analysis of the force and moment coefficients reveals the existence of a lateral force perpendicular to the streamwise direction in the case of the scale-separation WALE model, which suggests that the wake of the capsule may have some

preferential orientations during the vortex shedding. In the case of the classical version of the WALE model, no lateral force has been observed so far so that the mean flow is thought to be still axisymmetric after 100 units of non-dimensional physical time.

Finally, the last chapter of this work recalls the main conclusions drawn from the previous chapters.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

APA, Harvard, Vancouver, ISO, and other styles

12

Liu, Wen-Hao, and 劉文豪. "Composite Multivariate Multiscale Entropy Analysis." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/8byt6x.

Full text

Abstract:

碩士
國立交通大學
資訊科學與工程研究所
104
Entropy is used for measuring signal complexity. In order to understand the structural complexity of a signal, analysis of the complexity changes in multiple scales is the trend of entropy study. Costa, M. proposed the multiscale entropy analysis in time domain, but these low-frequency scales are unable to reveal the high-frequency information of the signal. The multiscale entropy analysis in frequency domain is soon developed. Use Empirical Mode Decomposition proposed by Norden E. Huang, extracting Intrinsic Mode Functions from the signal in different frequency band. Therefore, frequency scales are obtained by the cumulative sums of the intrinsic mode functions. But without objective measurements, these scales cannot be considered as explicitly defined. Because of the transient nature of intrinsic mode function, the Instantaneous Frequency inferred Power Spectral Density is used. We capture the features of scales by extracting the position and spread parameter of the distribution of scale signals in the PSD. The signal of each scale is described with three parameters: the position and the spread of the distribution, the complexity of the signal. In this research, we use frequency modulate signal, noise and noisy sinusoidal signal as examples to distinguish the trend of each signal. Also we use two status of Steady State Visually Evoked Potential signal: under 35Hz flickering stimuli and rest, then observe the trend of each status. We do notice the entropy decrease in the trend of stimuli frequency band, due to the potential response under stimulated state. Most important of all, this research provides an objective basis for multiscale entropy comparison between signals by capturing scale features of distribution in IF inferred PSD instead of using index. As a result, the multiscale entropy analysis of frequency domain tends to be completed.

APA, Harvard, Vancouver, ISO, and other styles

13

Wang, Chia-Hsiang, and 汪嘉翔. "Motor Faults Detection Using Multiscale Entropy." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/71007832910015705727.

Full text

Abstract:

碩士
元智大學
資訊管理學系
98
Spectrum analysis is generally used for online detection of motor faults. This study presents a novel approach to discover features that distinguish the vibration signals of a normal motor from those of an abnormal one. These features are obtained from the difference of multiscale entropy of a signal before and after the signal is denoised using wavelet transform , or just use multiscale entropy after the signal is denoised using wavelet transform. Experimental results show the classifier can effectively distinguish between normal and abnormal motors.

APA, Harvard, Vancouver, ISO, and other styles

14

Liu, Chun-Wei, and 劉峻維. "Multiscale Entropy Analysis and It's Clinical Applications." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/96179675971406192948.

Full text

Abstract:

碩士
國立東華大學
電機工程學系
103
This thesis focuses on the application of Multiscale Entropy (MSE) in the waveform contour analysis of digital volume pulse using the Crest Time (CT) series and also the interpretation of electromyographic (EMG) signals in urodynamic study. In Part One, the application of MSE in CT analysis was shown to successfully discriminate healthy individuals from those with diabetes mellitus type 2. Data on digital volume pulse were obtained from 93 individuals in three groups [Healthy young (Group 1, 20< age ≤40, n = 30), healthy upper-middle-aged (Group 2, age >40, n = 30), and diabetic (Group 3, n = 33) subjects]. Crest time, normalized crest time (NCT), crest time ratio (CTR), small and large-scale MSE on CT [MSESS(CT) and MSELS(CT), respectively] were computed and correlated with anthropometric (i.e., body weight/height, waist circumference), hemodynamic (i.e., blood pressure), and biochemical parameters (i.e., serum triglyceride, high-density lipoprotein, fasting blood sugar, and glycosylated hemoglobin). The results demonstrated higher variability in CT in healthy subjects (Groups 1 and 2) compared with that in diabetic patients (Group 3) as reflected in significantly elevated MSESS(CT) and MSELS(CT) in the former (p < 0.003 and p < 0.001, respectively). MSELS(CT) also showed significant association with waist circumference and fasting blood sugar as well as glycosylated hemoglobin concentration. In conclusion, using MSE analysis for assessing CT variation successfully distinguished diabetic patients from healthy subjects. MSESS(CT) and MSELS(CT) therefore may serve as noninvasive tools for identifying subjects with diabetes and those at risk. 　　Part Two of this thesis describes the application of MSE in the interpretation of EMG signals from the external urethral sphincter acquired during urodynamic study. In an attempt to explore the information hidden in the EMG signals that may be of prognostic significance for patients receiving surgeries for primary bladder neck dysfunction, 46 patients with voiding difficulty were divided into four groups: Patients with successful surgery (Group 1, n=18), patients with unsuccessful surgery (Group 2, n=9), patients with detrusor overactivity (Group 3, n=7), and those with detrusor external sphincter dyssynergia (Group 4, n=12). The results demonstrated the MSELS(EMG) of Group 1 is significantly higher than that of Group 2, whereas there was no significant difference between Group 1 and Group 3 (i.e., patients with normal external urethral sphincter function). Moreover, the MSELS(EMG) and MSESS(EMG) of Group 2 is significantly higher than those of Group 4. In conclusion, using MSE analysis for assessing EMG signals of the external urethral sphincter not only successfully distinguished patients with successful surgery from those with surgical failure, but also could serve as an indicator of the functional integrity of external urethral sphincter.

APA, Harvard, Vancouver, ISO, and other styles

15

Lin, Keng-Hsi, and 林耕希. "Bitcoin Price Dynamics Analysis Using Modified Multiscale Entropy and Multiscale Poincaré Plots." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/4m5962.

Full text

Abstract:

碩士
東海大學
資訊管理學系
107
Bitcoin, a cryptocurrency based on the application of blockchain technology, has attracted great attention from the global financial market and media for its novel concept different from traditional currencies. Bitcoin has become not only an instrument for payment, investment or risk aversion in the financial market, but also an important case of asset digitization in the context of the boom of digital finance technology. The purpose of the study was mainly to analyze the complexity of Bitcoin trading market, to facilitate understanding whether there is meaningful structure in the dynamic changes of Bitcoin market trading price and studying whether the occurrence of significant events in the world economy and the history of Bitcoin will affect Bitcoin market trading price. In the study, Bitcoin price data during the period from 31 July 2010 to 31 July 2018 were used as samples, and changes in Bitcoin market trading price were regarded as a non-linear time series. Bitcoin trading price data were a short-term time series, therefore, modified multiscale entropy was used in the study to analyze the complexity of Bitcoin trading market and compare with white noise and pink noise. In addition, multiscale poincaré plots were used in the study to implement graphic analysis to the time series of Bitcoin trading price, so as to understand the self-similarity herein. However, the results of data analysis using modified multiscale entropy show that the complexity of Bitcoin market is very low, which indicates that Bitcoin market is similar to white noise and is a relatively random time series. Moreover, the results of analysis using multiscale poincaré plots also show that the self-similarity of Bitcoin market price is very low, and is a random time series similar to white noise. Therefore, it has been proven that the results obtained by us applying such two methods are consistent. It is also found in another study that, the significant events occurred in the history will have an impact on the liquidity of Bitcoin market. Overall, the study shows that changes and movements of Bitcoin trading price is a time series featuring a low complexity, a high randomness, a low self-similarity and also a low future predictability. In addition, both Bitcoin market and trading price are prone to be affected by events.

APA, Harvard, Vancouver, ISO, and other styles

16

Wu, Ling-Chia, and 吳翎嘉. "Multiscale-Entropy-based Model for Fan QualityDiagnosis System." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/w2wpck.

Full text

Abstract:

碩士
國立臺灣大學
機械工程學研究所
106
Aiming at long term smart manufacturing goal, in solving the global problem of skilled labor shortage, production line and quality testing automation is one of the primary high agenda issues. In this research vibrational signal is used for fan QC as compared with conventional manufacturing factories which apply abnormal sound detection as index. Apart from traditional analytical tools RMS value and FFT, multiscale entropy, which estimates the complexity of signals is also adopted in the present study. Cooling fans will be affected by the turbulence air flow while it is operating, making its vibrational signal in a type of ‘Cyclostationary’. Traditional FFT has its limitations on analyzing cyclostationary signals. In this research, multiscale entropy is adapted to make the signal coarse-grained, decreasing the effect of turbulence. The multiscale entropy curves of the sample are found to have good repeatability, and also it gives the characteristic of the sample quality. A neural network model was developed in this research. The labeled samples that had been classified by the professional fan quality controllers were used to train the model. The first model obtained using 36 fans as the training samples, and the validation has been made with 9 new samples, with the accuracy 100 %. Repeated experiments were also carried out for further observation. The second model obtained was used to validate the result of the third repeated experiment, with the accuracy of 88.9 %. The approach has found to be succeessful in classifying fan quality by its vibrational signal.

APA, Harvard, Vancouver, ISO, and other styles

17

Lin, Yi-Chun, and 林怡君. "Multiscale Entropy of Reciprocal Movement in Fitts’ task." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/h4x8h2.

Full text

Abstract:

碩士
國立臺灣科技大學
工業管理系
107
Multiscale Entropy (MSE) is a popular tool for analysis to represent time series complexity at multiple scales in recent years. However, in MSE analysis there is a lack of relevant research on goal-directed tasks with input devices. In our study we review the relevant research in the concept of entropy, the reciprocal movement and the Fitts’ Law. Thus, the experimental environment is built under the framework of Fitts’ Law to design the display environment and define task difficulty and angle. The experiment is divided into two part. Experiment 1 is a basic repeated goal-directed task with reciprocal movement. Experiment 2 which considers the angle factor is a two-dimensional bivariate goal-directed task with reciprocal movement. By the OptiTrack Motion Capture System which can convert human characteristics into data, the trajectory of hand movement is collected for analysis to discuss the influence of different factors on the MSE. The results of the study were that the movement trajectory of using the stylus is more complex than mouse. When the task demand increases, the complexity of the movement trajectory will decrease. For angle factor, at large scale, it is confirmed that movement trajectory in 120-300 degree is more complex than 0-180 degrees. In the end, it is expected that the results of this study will contribute to the application of MSE.

APA, Harvard, Vancouver, ISO, and other styles

18

Lin, Ching-Yu, and 林慶諭. "Multiscale Entropy of Eye Movement in Website Interface Complexity." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/6ku45k.

Full text

Abstract:

碩士
國立臺灣科技大學
工業管理系
107
With the popularity of the Internet, the demand for web pages has changed. Users start pursuing a better experience. So developers are starting to focus on improving the web interface, but users still continual complaint about web’s complexity and difficult to use. Related research found that website complexity is a crucial factor lead to this situation. However, most of research on website complexity rely on subjective comments, and there is a lack of quantitative assessment. Therefore, our research attempts to establish an objective and quantitative method of website interface complexity. The main purpose of this research is to use Multiscale entropy to calculate the complexity of fluctuations of time series, based on the e-commerce website and generated three levels of complexity website interface. The experiment data were collected from 13 participants. And the task is about searching for objects in the web interface. Obtain objective eye movement data, heart rate variability, skin current response and subjective mental load assessment. And then multiscale entropy is applied to physiological data in order to use this analytical method to discuss changes between website interface complexity and physiological data complexity. The results show that the entropy value increase when the web interface complexity increase. Therefore, the eye movement signal can be quantified by multiscale entropy calculation to evaluate the web interface complexity. And when the complexity is in moderate, the mental load is the lowest, forming a positive U relationship. It is expected that the results of this study will contribute to the complexity of the web page.

APA, Harvard, Vancouver, ISO, and other styles

19

Huang, Yi-Ju, and 黃檍如. "The Application of Multiscale Entropy in Stock Index Analysis." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/44811537101104675515.

Full text

Abstract:

碩士
國立臺北大學
統計學系
102
The approaches of correlation coefficient, unit root test (such as DF test & ADF test), structural change test (such as Chow test), autoregressive conditional heteroscedasticity (ARCH), vector autoregression model (VAR model) or Johansen cointegration test, etc. are frequently used to test structural changes of stock market indices. However, there are some limitations when using these tools. The literature has found that the multiscale entropy (MSE) can be applied to time series to investigate the issue of change points. Based on this, this paper aimed to apply the multiscale entropy to the stock index of Taiwan Weighted Index (TWII), Hang Seng Index (HSI), Dow Jones Industrial Average Index (DJI), NASDAQ, Financial Times Stock Exchange Index (FTSE) and Cotation Assistée en Continu 40 (CAC40) to test their structural changes and determine the possible time of the change points. From the real data study, we find all of these stock indices have a common structure change point around September of 2008.

APA, Harvard, Vancouver, ISO, and other styles

20

Teng, Chih-Kai, and 鄧至凱. "Motor Abnormal Detection Using Zigzag Quantization of Multiscale Entropy." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/26643243354116462894.

Full text

Abstract:

碩士
元智大學
資訊管理學系
99
The vibrational signals of several motors for jet pumps and circulation pumps have been collected and used in the experiment in the research. The data are collected using one of the two processes. The first process stores the signals in the embedded system, and the signals are then manual moved to the database in batches. The second process uses wireless sensors to collect and transmit the signals directly to the database. Additionally, a dimension reduction method has been proposed by quantifing the degree of sawtooth of the MSE curves. Using too many attritubes incurs much overhead on the embedded system. By replacing the MSE attributes with the sawtooth attributes, fewer attributes are needed when building the classifier for abnormal detection.

APA, Harvard, Vancouver, ISO, and other styles

21

Teng, Ting, and 滕婷. "Multiscale Entropy Analysis of Heart Rate Dynamics in Physiological Aging." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/76880350748009581213.

Full text

Abstract:

碩士
國立陽明大學
物理治療暨輔助科技學系
99
Background. Aging declines the body structure or function. Many studies support the degree of aging is affected by not only the age but also the physical activity (PA). Hence, the concept of physiological aging can be reflected by combining the age and physical activity. However, the methods of quantitating physiological aging are biochemistry methods which are invasive and expensive, and physical signals, such as heart rate variability (HRV), which are easily affected by other factors. In recent years, a decrease in complexity of physical signals, measured by multiscale entropy analysis (MSE) of heart rate dynamics, is shown to be effective on differentiating the disease and age effect in human studies. However, it is uncertain whether the MSE is useful to quantify the degree in physiological aging. Purposes. This study aims to identify the relationship between physiological aging and complexity in healthy adults using MSE and to compare the sensitivity in response to physiological aging between MSE and HRV. Methods. A total of 111 healthy subjects (aged 19-85 years, 73% female) who had regular physical activity in 3 months were recruited. The participants answered the questionnaires (including basic data, the short version of International Physical Activity Questionnaire (IPAQ), diet, stress) and were taken the ECG recordings in sitting quietly for 5 minutes and during minimal activity for 60 minutes in order to conduct HRV and MSE analysis respectively. Based on their age and IPAQ, the participants were categorized into different age groups (young adult, middle-aged, and elderly) and PA groups (high, sufficient, and insufficient). ANCOVA and one-way ANOVA were used to compare the results between groups. The level of significance was 0.05. Results. Among age groups, the young adults showed the highest values of complexity in MSE, and the values of the elderly group were the lowest (p<0.05). Among PA groups, the MSE values of subjects with high PA were the highest, and the values of those with insufficient PA were the lowest (p<0.05). Among age and PA groups, the highest values of complexity in MSE were shown in the young adults with high PA, the second one was in the young adults with sufficient PA, and the lowest one was in the elderly with insufficient PA. A trend of higher MSE was found in the younger and more active PA group. The MSE values of middle-aged with high and sufficient PA were higher than that of the younger group with insufficient PA. In HRV, the older group had lower SDNN (p<0.05), and the other HRV parameters had no significant difference in age, PA, and physiological aging effects. Conclusions. MSE can reflect age and PA effects individually, and can observe the effect of sufficient PA on decreasing aging process. The sensitivity in response to physiological aging of MSE is higher than the sensitivity of HRV. MSE is suggested to be used as an objective and non-invasive method in discriminating the levels of physiological aging, which maybe also helpful to apply for the outcome measure of health promotion.

APA, Harvard, Vancouver, ISO, and other styles

22

Fu, Szu-Kai, and 傅思凱. "Establish the Distinct Pattern of Multiscale Entropy in Myocardial Infarct." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/48105522407239582533.

Full text

Abstract:

碩士
臺北巿立體育學院
體育與健康學系碩士班
101
Background : The automatic nerve systems are usually studied by the heart rate variability (HRV) analysis. Analysis methods of HRV usually derived from linear mathematics, however, multiscale entropy (MSE) derive from the nonlinear mathematic system and detect minor physiological variations. MSE is a method that provided accurate prognosis by studying randomness in physiological signal. The purpose of this study is to distinguish the difference between the myocardial infarction subjects (MI) and normal subjects (NOR) with MSE. Methods : The results of MSE are analyzed by different window size for moving window on scales and normalization. RR-interval of MI and NOR, as well as, research data will be available at http:// physionet.org. Results : When the window size were 5 for moving window on MSE and normalization with UCA1-5 or UCA2-6 , it could find the most differentiate between MI and NOR. Conclusion : After moving window and normalization MSE can distinguish the difference between MI and NOR. In future, it could be used to help diagnosis or prognosis MI, and also to judge the degree of the condition.

APA, Harvard, Vancouver, ISO, and other styles

23

Lin, Jr-Chiang, and 林志強. "The application of Multiscale entropy in structural changes of time series." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/15630009737535553457.

Full text

Abstract:

碩士
國立臺北大學
統計學系
99
In the recent years, multiscale entropy (MSE) has been widely adopted for engineering or medical researches and for analysis on the complexity of things researchers interest in, which all bringing in excellent research results. Therefore, the main purpose of this research is to use Sample entropy (SampEn) to calculate the complexity of fluctuations of time series. We use multiscale entropy at different time scales to explore the curve change of sequence data volatility. By observing and researching considerable amount of computer simulation data, we find out the way to use multiscale entropy to evaluate the possible time of structural changes of time series. Through this approach, the original sequence will be separated into several subsequences in case the data of subsequences is not enough. If the multiscale entropy curves among the sequences fluctuate in the same way, it means these sequences do not have structural changes. On the contrary, if one curve fluctuation from one subsequence is different from other subsequences’, this should mean this sequence has structural change and the change point may exist within it. These curve changes of the multiscale entropy and other different subsequences will be divided into several more subsequences; then we search over and over until we find the structural change point within the small interval.

APA, Harvard, Vancouver, ISO, and other styles

24

Tsai, Hsin-Ju, and 蔡炘茹. "Study on Cardiorespiratory Interactions Based on Multiscale Entropy and Phase Relationship." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/u2jeyr.

Full text

Abstract:

碩士
國立交通大學
生醫工程研究所
107
This research is aimed to investigate the cardiorespiratory interaction of different mental-stress states by multiscale entropy analysis, nonlinear interdependence analysis and the phase difference analysis. Multiscale entropy provides the information of the complexity of R-R-interval at different mental-stress levels. Nonlinear interdependence analysis mainly involves the reconstruction of phase space trajectory from HR (heart-rate) and RP (respiratory) sequences to estimate the similarity index (SI) to analyze the influence of these two signals on each other. In phase difference analysis, we present a new, yet, more straightforward scheme to evaluate the instantaneous phase differences based on empirical strategies and analyze the probability of occurrence of the phase difference in different phase ranges. This study involves 33 subject, 8 Zen-meditation practitioners (experimental group) and 25 healthy, ordinary control subjects without any meditation experience. According to the results of multiscale entropy, the most control subjects had higher entropy and complexity in CAT sessions, and had lower complexity in breathing-control (BC) session. Although Zen-meditation practitioners (age: 51-62) were much older than controls (age: 20-24), average entropy of Zen-meditation group is approximately the same as which of control group in Rest sessions. It indicates that the cardiorespiratory functioning may be well preserved via Zen-meditation practice. In nonlinear interdependence analysis, BC session induces stronger influence of RP on HR than the influence of HR on RP. Moreover, the group average of Zen-meditation group is higher than which of control group. The results provide the evidence that Zen meditation enhance the nonlinear interdependence between HR and RP. In phase difference of HR and RP, smaller phase difference between HR and RP reflecting higher cardiorespiratory synchronization appears either at the Zen meditation or in the breathing-control session.

APA, Harvard, Vancouver, ISO, and other styles

25

林庭毅. "Bearing Fault Diagnosis System based on Multiscale Root Mean Square, Multiscale Entropy,Fisher Score and Backpropagation Neural Network." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/14765502253830447132.

Full text

Abstract:

碩士
國立臺灣師範大學
電機工程研究所
100
Machine condition monitoring is gaining importance in industry because of the need to increase reliability and to decrease the possibility of production loss due to machine breakdown. The use of vibration signals is quite common in the ﬁeld of condition monitoring of rotating machinery. By comparing the signals of a machine running in normal and faulty conditions, detection of fault types of bearing defects is possible. Generally, a bearing fault diagnosis process can be decomposed into three major steps: feature extraction, feature selection and fault condition classification. In this dissertation, we propose a fault detection algorithm to distinguish different types of bearing fault. Firstly, the features of vibration signals collected from different conditions were extracted by multiscale entropy (MSE) and multiscale root mean square (MSRMS) algorithm. Secondly, the optimal feature set is selected by Fisher score. Thirdly, the optimal feature set and backpropagation neural network (BPN) was used to build the model of fault classifier. In our simulations, the vibration signal datasets of bearing from Case Western Reserve University (CWRU) are utilized. Experimental results demonstrate that the proposed algorithm provides a high accuracy of prediction on the test data.

APA, Harvard, Vancouver, ISO, and other styles

26

Tsai, Meng-Shiang, and 蔡孟翔. "The application of Hilbert-Huang transformation and multiscale entropy on electrocardiogram data." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/63395281688034635318.

Full text

Abstract:

碩士
國立臺北大學
統計學系
98
In the traditional method of spectrum analysis . Data must be consistent with linear and stationary characteristics . However, this will confine the application of real world. Instantaneous amplitude and Instantaneous frequency through can be calculated Hilbert transform . Has been widely application in all domain . But , if data done directly conversion will cause false consequence . Therefore this article introduction that a new method , called Hilbert-Huang transform . First of to the data do Empirical Mode Decomposition . Generate many of Intrinsic Mode functions , Then to the Intrinsic Mode functions do Hilbert transform . Finally , make use sample entropy calculate systems complexity , and use approximate multiscale entropy calculating at different scales . To explore heart disease of the curves vary .

APA, Harvard, Vancouver, ISO, and other styles

27

Yeh, Chih-Wei, and 葉知維. "Feature Selection of Multiscale Entropy of Congestive Heart Failure Via Machine Learning." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/5yqj24.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

李易宗. "A Gearbox Fault Diagnosis System Base on Enhanced Morlet Transform, Demodulation Spectrum, Multiscale Entropy, Multiband Spectrum Entropy and Decision Tree." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/96485788837645455966.

Full text

Abstract:

碩士
國立臺灣師範大學
機電科技研究所
100
Gearboxes play an important role in industrial applications. Typical faults of gears include pitting, chipping, imbalance, loss-of-lubrication and more seriously, crack. When a gear has a fault, the vibration signal may carry the signature of the fault in the gears. Therefore, fault detection of the gearbox is possible by analyzing the vibration signal by different signal processing algorithms. In this dissertation, we propose a gearbox fault diagnosis system to distinguish different fault types of the gearbox. Firstly, signatures of the gear faults were extracted by the demodulation spectrum, image entropy, multi-scale entropy (MSE) and multiband spectral entropy (MBSE). Secondly, these extracted signatures were used to build a decision tree (DT) based model. In our simulations, the vibration signal datasets of gearbox from Industrial Technology Research Institute (ITRI) are utilized. In experimental results, the trained DT models have shown high accuracy of fault detection and fault classification on the test set.

APA, Harvard, Vancouver, ISO, and other styles

29

Huang, Ting-Hsuan, and 黃婷暄. "Damage Quantification of 3D-printed Structure based on Composite Multiscale Cross-sample Entropy." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/283rub.

Full text

Abstract:

碩士
國立交通大學
土木工程系所
108
This study aimed to combine 3D printing technique and Composite Multiscale Cross- sample Entropy (CMSCE) to apply to structural health monitoring(SHM) system, and to further explore a criterion for single-story structural damage index quantification. By quantifying the damage index, a SHM system suitable for real-world structure was established. An ETABS numerical model of a seven-story 3D printed structure was first conducted, and by setting various bracing conditions as failure modes, the damage of actual structure was properly simulated. Regarding structural acceleration signal as the biological signal of structure, CMSCE was used effectively to indicate the location of damage. Moreover, damage index was also used to shorten the judging time and to improve the accuracy of the system. With the damage index quantification, the impact of various degrees of damage on the analysis results could be observed. Based on the results of numerical simulation, the 3D printing structure experiment was conceived. Firstly, the earthquake simulation shaking table was used to conduct experiments of single-story severe damage cases, single-story moderate damage cases and single-story slight damage cases. Obtaining signals from these cases to do CMSCE analysis. Structural damage detection was performed through the entropy curve and the damage index figures to determine the damage location and damage degree, and to quantify the damage index. By quantification, this study proposed a set of objective and reliable method, combining the emerging 3D printing technology with the application of the damage index to explore its feasibility in the field of SHM system.

APA, Harvard, Vancouver, ISO, and other styles

30

Wang, Jia, and 王嘉. "Constructing the rotary machine real-time detection system using multiscale entropy-machinery method." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/19163512707008052939.

Full text

Abstract:

碩士
國立臺灣科技大學
機械工程系
98
In the industrial sector and people life, rotating machinery is a common and useful dynamic system. In the past RMS (Root Mean Square) and FFT (Fast Fourier Transform) are the two commonly used detection methods for rotating machinery, but these two methods can only do a basic test for mechanical system. In order to improve the testing quality and efficiency an innovative detection method for rotating machinery with MSE-M (Multi-scale Entropy-Machinery) method is introduced in this thesis. MSE algorithm has been widely used in the field of biomedical research to investigate and analyze many biomedical signals from human body. However, it has not been applied to study mechanical systems successfully. A new signal analysis method called MSE-M (Multi-scale Entropy-Machinery) from conventional MSE (Multi-scale Entropy) is developed to investigate signals with periodical characteristics and applied into the field of rotating machinery. The main contribution of this study is to develop the MSE-M method and set up a series of experiments with turning processes and bearing systems to verify it. Finally a prototype of real-time monitoring method for rotating mechanical system has been built.

APA, Harvard, Vancouver, ISO, and other styles

31

Chien-Chin, Chen, and 陳建欽. "The effect of circuit exercise intervention on balancing capability in elderly with multiscale entropy." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/15034768284143829146.

Full text

Abstract:

碩士
國立新竹教育大學
人資處體育碩士專班
101
Purpose: The purpose of this study was to investigate the effects of circuit exercise balancing capability in elderly with multiscale entropy. Method: Fifty-five elderly 55 to 80 years old appearance of integrity and ability to walk alone were randomly assigned to the following three groups. Twenty elderly were in the exercise habits group (age=66.1±8.0yr, ht=159.8±7.0cm, wt=62.8±9.0kg), another twenty elderly were in the circuit exercise group (age=63.9±5.5yr, ht=159.1±9.4cm, wt=59.2±9.7kg), who attended the circuit exercise at 40 minutes per day, 3 days per week for 12 weeks. Fifteen elderly were in the control group (61.5±6.5yr, ht=161.7±7.5cm, wt=62.9±9.0kg). The data were analyzed by multiscale entropy, and assessed by t-test and one-way analysis of covariance (one-way ANCOVA). Result: 1. Exercise habits significantly improved the balancing capability of elderly both eyes open and eyes closed during 0-5 seconds (p<.05). 2. Exercise habits significantly improved the balancing capability of elderly both eyes open and eyes closed during 5-60 seconds (p<.05). 3. The circuit exercise intervention significantly improved the balancing capability of elderly of eyes open during 0-5 seconds (p<.05), but didn’t significantly influential on eyes closed (p>.05). 4. The circuit exercise intervention significantly improved the balancing capability of elderly of eyes open during 5-60 seconds (p<.05), but didn’t significantly influential on eyes closed (p>.05). Conclusion: This study indicated that Regular exercise can improve the elderly terminate gait and static balancing capability both eyes open and eyes closed. The circuit exercise intervention can improve the elderly terminate gait and static balancing capability of eyes open, but can’t improve the terminate gait and static balancing capability of eyes closed. Keywords: multiscale entropy, circuit exercise, balancing capability

APA, Harvard, Vancouver, ISO, and other styles

32

Lin, Yi-ting, and 林宜亭. "Postural balance ability analysis for inpatients after laryngeal microsurgery in anesthesia using multiscale entropy." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/35503062168244906781.

Full text

Abstract:

碩士
元智大學
工業工程與管理學系
97
Instead of physical movement evaluations, the vital sign assessment is a common practice for the recovery room to decide on discharging postsurgical patients. An experiment on evaluating the pre- and post-anesthesia body balancing ability by measuring and analyzing the center of pressure (COP) signals was conducted on 22 volunteers receiving laryngeal microsurgery (LMS) from a medical center. This study investigated the anesthesia recovery time of post-LMS patients with postural balancing indicators to assost doctor to determine the time of discharging postsurgical patients. Complexity is an indicator for evaluating health condition. With complexity concept, before anesthesia, complexity is high and balancing control and environmental adaptability are better; after anesthesia, complexity is low and balancing control and environmental adaptability become weaker. Signals obtained from the experiment are divided into two groups: medio-lateral (ML); and anterior-posterior (AP). High-frequency signals with greater energy were obtained with the empirical mode decomposition (EMD). By analyzing the complexity and assessing the difference in balancing ability of subjects before and after anesthesia with multiscale entropy (MSE), the speed of anesthesia metabolism and balancing ability recovery in the subjects are understood. Results of the repeated-measure ANOVA on complexity and comparison of center of pressure (COP) shift distance show that (1) LMS patients have normal vital signs after entering the recovery room, indicating that vital sign and complexity changes are inconsistent; (2) neither the ML nor the AP balancing ability is recovered to the pre-anesthesia conditions 45 minutes after anesthesia, and (3) 1-2 hours is needed to recover to the pre-anesthesia conditions, and the ML balancing ability recovers more slowly than the AP balancing ability. As the results of this study can help doctors to better understand the anesthesia recovery time of LMS patients, this can save medical resources and increase bed utilization rate if LMS patients can be discharged from the hospital earlier.

APA, Harvard, Vancouver, ISO, and other styles

33

Lin, Cheng-Feng, and 林成峯. "Multiscale Entropy Analysis of Pulse Wave Velocity for Assessing Atherosclerosis in the Aged and Diabetic." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/53760488729776761189.

Full text

Abstract:

碩士
國立東華大學
電機工程學系
99
Many people die each year of atherosclerosis-related diseases, so estimation of the extent of human atherosclerosis is very important, especially for the elderly and diabetics. The thesis will focus on two major risk factors, atherosclerosis for age and glycemic control, utilizing pulse wave velocity as the index of atherosclerosis for research. The human body is a complex physiological system, and in which the physiological signals are likely to contain all the information. A nonlinear and non-stationary analytical method - multiscale entropy is proposed in this thesis to analyze the time series of pulse wave velocity and then compare with the average of pulse wave velocity. In this paper a total of 61 subjects were divided into four groups by age, disease and glycosylated hemoglobin (Group1: young, Group2:middle-aged, Group3:diabetic well-controlled, Group4:diabetic poor-controlled). The results show that dynamic index –(Multiscale Entropy Index large scale, MEILS)of foot is superior to the average of pulse wave velocity in reflecting the atherosclerosis differences between the four of them. The highest value of MEILS for young group is observed, and followed by middle-aged, diabetic well-controlled, and diabetic poor-controlled.

APA, Harvard, Vancouver, ISO, and other styles

34

Su, Hsiu-Yi, and 蘇修儀. "Postural balance ability analysis for outpatients after Port-A surgery in anesthesia using multiscale entropy." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/69605224239998640561.

Full text

Abstract:

碩士
元智大學
工業工程與管理學系
97
Currently, the criterion for hospital discharge after postural surgery is evaluated by using basic physiological indices of the patients; an index for evaluating the body balance of the patient is ignored. To avoid patient failing due to incomplete metabolism of the anesthetic, this study aims to observe the approximate time required for patients using various anesthetics to recover pre-surgical physical activity, the relation between age and balance recovery after the use of anesthetic, and the required recovery time for different age groups. The balance evaluation system used in this study aims to assist the nurse to evaluate whether the ambulatory surgery patient may leave the hospital by providing references; it further aims to improve the safety of the patient after leaving the hospital. The subjects of the study were 87 patients who receive Port-A surgery from a medical center. The study was designed to collect standing center of pressure (COP) from the patients at 3 time points (45min., 1hr., and 2 hrs.) after the surgery; through empirical mode decomposition, high frequency signals are obtained. Then, complexity analysis of the multiscale entropy and evaluating the subject balance variation were performed before and after the surgery. The study found that patients who used combined anesthesia recovered their balance after approximately 65-85 minutes in the recovery room; whereas, patients who used single anesthesia gradually recovered their balance after approximately 45 minutes. In addition, the direction of the balance could be used to differentiate the type of anesthesia the subject received. The medio-lateral (ML) and anterior-posterior (AP) balance of the youth-middle age group that used combined anesthesia almost recovered to the presurgical condition after 65-85 minutes of rest. The ML balance of the single anesthesia users gradually recovered to the presurgical condition after 45 minutes of rest while the AP balance almost had recovered to the presurgical condition at that time. The balance of the elder group that used combined anesthesia had almost recovered to the presurgical condition after 45 minutes of rest and the ML and AP balance of the elder group that used single anesthesia had recovered within 45 minutes according to the study design. For the two anesthesia types studied, we found that the ML balance was affected more by the anesthesia with a slower recovery process. The study observed that anesthesia indeed affects balance ability, and suggested that the balance ability evaluation would be included as a reference index for the hospital discharge of ambulatory surgery patients.

APA, Harvard, Vancouver, ISO, and other styles

35

Gaudêncio, Andreia Sofia Feitor. "Entropy measure algorithms for biomedical applications." Master's thesis, 2019. http://hdl.handle.net/10316/87936.

Full text

Abstract:

Dissertação de Mestrado Integrado em Engenharia Biomédica apresentada à Faculdade de Ciências e Tecnologia
Atualmente, os sinais e imagens biomédicas são fundamentais para o diagnóstico clínico. No entanto, em alguns casos, para um clínico menos experiente a sua interpretação poderá ser uma tarefa bastante difícil. Para algumas doenças, até clínicos com vasta experiência podem demonstrar dificuldades em quantificar e identificar os vários estádios da doença em questão devido à sua natureza.Desde os anos 1990' e, de acordo com a teoria da informação, surgiram várias medidas de entropia com o intuito de estudar a complexidade de sinais e imagens biomédicas. Além disso, a análise de múltiplos fatores de escala foi introduzida com o intuito de permitir uma visão detalhada dos dados em questão. Um valor de entropia elevado num sinal, imagem, ou volume revela uma elevada irregularidade do mesmo. Até agora, foram efetuados poucos avanços científicos no âmbito das medidas de entropia para a análise de volumes.Baseado no conceito de entropia difusa ("fuzzy entropy"), foram propostos três novos algoritmos de medidas de entropia, todos revelando inovações. Antes da sua aplicação em dados biomédicos, estes foram testados e validados em dados sintéticos, de acordo com os métodos na literatura.Em primeiro lugar, foi desenvolvida uma definição alternativa de de entropia difusa unidimensional (FuzEn1D) bem como a sua versão multi-escala (MFE1D), por forma a analisar a complexidade de sinais áudio de roncos bem como os estádios associados de síndrome de apneia-hipopneia do sono (SAHS). Este método revelou ser uma ferramenta interessante, que uma vez aperfeiçoado, poderá vir a ser utilizado no futuro para mais estudos.Posteriormente, com o intuito de processar imagens dermoscópicas, foi introduzida a entropia difusa bidimensional colorida (FuzEnC2D) para conduzir um estudo de microcirculação sangu ínea e, um estudo para identificação de lesões de pele. Conseguiu-se provar que FuzEnC2D poderá ser de grande interesse para ambos os estudos. No caso do estudo de microcirculação sanguínea, demonstrou-se que existem diferenças estatísticas entre uma região da pele em repouso e, uma região vasodilatada do mesmo tamanho e no mesmo indivíduo. Adicionalmente, provou-se que são verificadas diferenças estatísticas entre as demais lesões da pele consideradas no estudo (nevos comuns, nevos atípicos e, melanoma).Finalmente, é proposta ainda a entropia difusa tridimensional (FuzEn3D) e a sua versão multi-escala (MFE3D), para avaliar conjuntos de scans CT como um só volume de modo a proceder à identificação e ao estudo da progressão da doença Fibrose Pulmonar Idiopática (IPF). Neste último estudo, foi possível identificar a existência desta doença extremamente mortal entre dois grupos diferentes (um grupo de indivíduos saudáveis e, um grupo de indivíduos que sofrem de IPF).
Nowadays, biomedical signals and images are of utmost importance for medical diagnosis. Nevertheless, in some cases, for a less experienced doctor, their interpretation can become a very hard task. For some diseases, even experienced doctors can have difficulties in quantifying and identifying several stages due to the disease's nature.Since the 1990s, based on information theory, several entropy measures emerged to study biomedical signals and images' complexity. Moreover, multiple scale analysis has been introduced to have a more detailed view of the studied data. A high entropy value on a signal, image or volume reveals a high irregularity level. So far, little scientific advances have been made in analyzing volumes with entropy measures.Based on fuzzy entropy, we propose three new entropy algorithms measures, all with innovations in the field. Before applying them to biomedical data, all of them were tested and validated on synthetic data, according to previous literature approaches.First, an alternative unidimensional fuzzy entropy (FuzEn1D) definition and the multiscale version (MFE1D) has been developed to analyze snoring audio signals' complexity and Sleep Apnea-Hypopnea Syndrome (SAHS) stages. This method revealed to be an interesting tool, that with some improvements, might be used in the future for further studies.Moreover, to process dermoscopic images a bidimensional colored fuzzy entropy (FuzEnC2D) algorithm was introduced to perform a cutaneous microcirculation study and the identification of skin lesions. It has been proven that FuzEnC2D can be of great interest to both microcirculatory assessment and melanoma identification. For the microcirculation study, statistical differences have been found between a relaxed skin region and vasodilated one of the same sizes for the same individual. Additionally, statistical differences have also been verified between the skin lesions considered (common nevi, atypical nevi, and melanoma).Finally, a tridimensional fuzzy entropy (FuzEn3D) and its multiscale version (MFE3D) is proposed to evaluate sets of CT scans as volumetric data for identification of idiopathic pulmonary fibrosis (IPF) and stage progression. In this study, the existence of this deathly disease between two different groups (a group of healthy subjects and one group of subjects diagnosed with IPF) was identified.

APA, Harvard, Vancouver, ISO, and other styles

36

Zhuang, Wei-Yo, and 莊威佑. "Research of acupuncture Zusanli on whole body peripheral blood flow ,autonomic system activity and Multiscale Entropy." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/s5y484.

Full text

Abstract:

碩士
國立東華大學
電機工程學系
102
Acupuncture is a traditional Chinese medicine method which is used acupoints to cure many diseases. On 1996 WHO announced 64 indications for acupuncture treatment. According to the theory of Chinese medicine , Zusanli (ST-36) is one of the four most important acupoints because it coordinates the functions of the immunological and gastrointestinal systems. But the detailed mechanism of acupuncture is yet not clear and effect of acupuncture also lack scientific evidence. Therefore our research attempted to measure the pulse signal of nailfold microcirculation through non-invasive our invented microcirculation detector. Our research subjects were 28 healthy young adults (22 males and 6 females). We measured their nailfold peripheral blood flow and autonomic activities by computing the area under the pulse volume curves and Heart Rate Variability (HRV) through photoplethysmography (PPG) and electrocardiography (ECG) before and after acupuncture at Zusanli. Moreover, complexity of physiological signals was compared with multiscale entropy (MSE) and short time MSE (sMSE) before and after acupuncture. Bland Altman analysis of the perfusion index (PI) showed that the majority of values were located within 1.96 SD. This suggested our data has high consistency and our invented microcirculation detector has high accuracy.The second result demonstrated significant elevation of peripheral blood flow in all 28 subjects during and after acupuncture. On the other hand, significantly reduced sympathetic activities and elevated parasympathetic activities were noted in subjects with body mass index (BMI) <25. It suggested after acupuncture healthy young adults parasympathetic activities elevate. Additionally, MSE analysis of R-R interval (RRI) from 5-minute recording of ECG from subjects with BMI<25 before and after acupuncture showed significantly elevated sMSE immediately after acupuncture. However, no significant difference was noted in MSE between the two time points. In conclusion, the results of our study demonstrated that acupuncture at Zusanli augments systemic parasympathetic activities and peripheral microcirculation. Furthermore, sMSE revealed increased physiological complexity after acupuncture for individuals of normal healthy weight (BMI <25).

APA, Harvard, Vancouver, ISO, and other styles

37

Chen, Yu-Ching, and 陳育慶. "Integration of Refined Composite Multiscale Cross-sample Entropy and Backpropagation Neural Network for Structural Health Monitoring." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/a49mac.

Full text

Abstract:

碩士
國立交通大學
土木工程系所
108
This study aimed to solve the issues which was the way of distinguishing entropy value and decreased the occurrence of undefined entropy value on the entropy method. Therefore, refined composite multiscale cross-sample entropy (RCMSCE) was utilized to enhance the reliability of entropy value and a new structural health monitoring strategy based on RCMSCE and artificial neural network. A neural network model is developed in accordance with a numerical model which is derived from the entropy value under the ambient vibrations. First, RCMSCE was implemented to extract the damaged feature and used ETABS to generate training samples which was changed stiffness terms to construct various damage pattern. A neural network model was trained and built by the entropy value with these damage patterns. After a seismic event, the proposed artificial intelligence-based structural health monitoring is employed to detect damage location and extent. In this study, a seven-story model was create to validate the performance of proposed method. Subsequently, a seven-story steel benchmark experiment with fifteen damage cases was conduct to compare the difference between numerical and experimental model. The confusion matrix was applied to evaluate the results. The performance evaluation of the proposed Structural Health Monitoring system showed the increase of accuracy to locate damage.

APA, Harvard, Vancouver, ISO, and other styles

38

Chen, Hong-Ruei, and 陳鴻睿. "The Immediate Effects of Overnight Continuous Positive Airway Pressure Ventilation Using Short Time Multiscale Entropy Method." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/31437274386059030448.

Full text

Abstract:

碩士
國立東華大學
電機工程學系
101
Continuous positive airway pressure (CPAP) is a standard hospital treatment for patients with obstructive sleep apnea (OSA). Previous research has proven that long-term and regular provision of CPAP treatment can reduce the incidence of cardiovascular diseases, and improve vascular health and autonomic nerve function in patients with OSA. However, few studies have considered the effects of short-term CPAP treatment on patients. This study used a self-made air pressure sensing system (APSS) as a signal acquisition platform, and collected data on patients with moderate to severe OSA who were undergoing polysomnography (PSG) or CPAP titration treatment at the Kaohsiung Chang Gung Memorial Hospital Sleep Center. A total of 35 patients with moderate to severe OSA who had never received relevant treatment participated in this study. These patients were divided into Group 1, comprising 22 patients receiving a PSG exam for the first time, and Group 2, comprising 13 patients undergoing CPAP titration for the first time. A 5-minute stable pulse signal was obtained from each patient before and after PSG or CPAP titration, with the patient awake and in a supine position. The pulse-pulse interval (PPI) of the signal was obtained, and three indicators of frequency-domain heart rate variability (HRV) were employed to evaluate autonomic nerve function before and after the experiment. In addition, a multiscale entropy (MSE) algorithm, which is used to evaluate physiological signal complexity, was modified to short time MSE (sMSE), which is more appropriate for short-term signal length computations. The sMSE was employed to rapidly evaluate the change in overall health status of the patients before and after the experiment. The experimental results indicated that the patients in Group 1 showed significant increases in sympathetic nerve activity after the experiment. Their LF/HF values, which represent balance in autonomic nerve activity, also exhibited significant increases. However, the sMSE1 physiological signal complexity indicator showed a significant decrease. By contrast, the LF/HF value of the autonomic nerve activity in Group 2 patients did not show significant changes before and after the experiment. Nevertheless, the sMSE1, sMSE2, and sMSE3 indicators for Group 2 patients showed a significant increase. In summary, this study adopted frequency-domain HRV indicators and the sMSE indicator (which reflects the overall health status) to observe enhancements in the autonomic nerve function and overall health status of patients receiving short-term CPAP treatment. The results elucidated the immediate therapeutic effects and health benefits of CPAP, and can be used to facilitate improving the willingness of patients to undergo CPAP treatment.

APA, Harvard, Vancouver, ISO, and other styles

39

Chang, Kai-Yu, and 張凱喻. "Multiscale Cross-Approximate Entropy Analysis for Assessing Atherosclerosis in the Aged and Type II Diabetic Patients." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/m75ssa.

Full text

Abstract:

碩士
國立東華大學
電機工程學系
100
The Translational Medicine is indeed one of the crucial links regarding medical research for it has sped up the developing process from basic medical science to clinical research and application. As far as current clinical research is concerned, however, more than a hundred physiological signals required to be monitored in order to describe the human being’s physiological system, and the existing approaches for analysis are rather complicated to employ. In light of that, how to successfully describe the human being’s physiological system adaptation- as well as function-wise with minimum signals but bearing the most physiological significance is an aspect waiting to be probed into. This study used the Multi-Scale Cross-Approximate Entropy (MCAE) and analyzed the R-R Interval (RRI) and the Pulse Transit Time (PTT) sequences to observe the differences of cardiovascular systems among four groups, Group 1: healthy young people, Group 2: healthy elderly people, Group 3: well-controlled Diabetes Mellitus Type II patients, and Group 4: poorly-controlled Diabetes Mellitus Type II patients, and then compared the MCAE with an older type of entropy, i.e. Multi-scale Entropy (MSE). This study has found that the MSE cannot effectively tell the difference between Group 3 and Group 4; however, the MCAE can effectively tell the differences resulted from aging and diseases among the four groups. In short, this study has succeeded in applying the multi-scale as well as multi-dimensional MCAE to assess the human being’s cardiovascular system, and the impact caused by the control over the blood sugar of the Diabetes Mellitus Type 2 patients.

APA, Harvard, Vancouver, ISO, and other styles

40

Shih-Kao and 高識. "Multiscale Entropy Analysis to Study the Data of Force Plate and Inertial Sensor under Static Balance Measurement." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/dtpx2s.

Full text

Abstract:

碩士
元智大學
工業工程與管理學系
106
Static balance generally refers to the body (mainly the head) does not move, the body's ability to maintain posture for some time. The traditional method of measuring static balance is to stand in one eye with closed eyes in terms of the number of seconds as the balance of strength. A relatively new method is to use a force plate to record the pressure center of the subject and analyze the data. Although the force-measuring board has a strong function and accuracy, but bulky, the price is expensive. Inertial sensor is a kind of balance measuring instrument consisting of accelerometer, gyroscope and magnetometer. Due to its high performance-price ratio and small volume, inertial sensor is often used as a research tool in many scholars' studies on balance and gait in recent years. Multi-scale entropy is a new method, which is generally used as a measure of the complexity index of a finite-length time series. That is, the complexity of the physiological signal is quantified as an index and has drawn much attention in recent years. These indices are very important for evaluating dynamic biological control systems Diagnostic models are of potential importance. In the past, the inertial sensor and force plate data features were analyzed by scholars. However, no multi-scale entropy analysis was used to explore the data of the two devices. This study uses the complexity obtained by multi-scale entropy analysis as an index to investigate the static equilibrium data collected by the force-measuring plate and the inertial sensor. This study recruited 15 young people as subjects, tied inertial sensors at the site of spine L3 and stood on the force-measuring plate for four static balance measurements and collected the force-measuring plate and the inertial sensor Data import force plate characteristic value, inertial sensor characteristic value and multi-scale entropy analysis, discuss the result. The results of this study show that the relative balance of inertial sensors in four kinds of motions is in accordance with the force plate, but the size of features in anterior-posterior and medio-lateral of the three motions does not accord with the force plate. In terms of complexity index, the complexity of the force-measuring plate and the inertial sensor is similar in the case of better balancing ability, but the complexity indexes of the two are different when the balancing ability is not good.

APA, Harvard, Vancouver, ISO, and other styles

41

Lee, Chih-Yuan, and 李志遠. "Applying Multiscale Cross-Approximate Entropy Analysis to Measure the Complex Fluctuation between RRI and PPG Amplitude Series." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/46692485564278329238.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Chang, Hsuan-Chi, and 張軒齊. "Evaluating The Effects of Short-term Diet Supplementation on RRI Complexity by Multiscale Entropy Methods in Young Adults." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/87754578467390180317.

Full text

Abstract:

碩士
國立東華大學
電機工程學系
103
Multiscale entropy is a methods to assess physiological complexity of human body, it has been applied in many biomedical related fields. In recent years, people have been more aware of healthful diet. Previous studies have shown that because of the difference diet habit and lifestyle in young adults, the nutrients in young adults are generally lower than in healthy elder’s. Therefore it’s a important issue to estimate the healthy degree of young adults. This study aimed at assessing therapeutic impact of short-term diet supplement on physiological complexity by multiscale entropy methods in young adults.Fifteen healthy young adult males divided into two groups according to the ratio of serum triglyceride (TC) to serum high-density lipoprotein cholesterol (HDL): Group 1 (TC/HDL ratio>4.1, n=7) and Group 2 (TC/HDL ratio≦4.1, n=8) underwent demographic, anthropometric, serum biochemical, skin carotenoid count (SCC), pulse-wave velocity (PWV), dilatation index (DI) by Bioscanner, ECG-PWV and APSS and analyses physiological complexity by multiscale entropy methods. Although the results demonstrated no notable difference in conventional anthropometric and serum biochemical parameters between baseline and 3-month values for both groups, in vivo parameters of SCC and arterial stiffness (PWV) were significantly improved in both groups after 3 months of diet supplementation.Moreover, vascular endothelial function (DI) and physiological complexity(MSE, sMSE, MMSE) showed improvements only in Group 2 after three months. Besides, SCC exhibited significant correlations with waist circumference, diastolic blood pressure, HDL, TC/HDL, DI, and PWV. The findings suggest that short-term carotenoid-based diet supplementation is beneficial to young males for improving vascular health and overall physiological status

APA, Harvard, Vancouver, ISO, and other styles

43

Halliday, Drew. "Variability in cortical haemodynamic response during executive function tasks in older adults using functional near infrared spectroscopy." Thesis, 2016. http://hdl.handle.net/1828/7461.

Full text

Abstract:

Variability in neural activity has historically been treated as noise, in favour of deriving estimates based on central tendency (e.g., mean). Recently, researchers have shown that variability and mean confer different sources of information and that increased variability in neural activity is associated with superior behavioural performance and that it decreases during late-life. Although mounting evidence suggests that neural variability is beneficial, it is less clear whether these findings are driven by within- or between-person factors and whether they are apparent during higher-order cognitive tasks. Further, variability can be derived in several different ways, drawing into question its congruence across operationalizations. The present investigation sought to separate within- and between-person sources of variance in order to ascertain what was driving any observable effects in three operationalizations of cerebral oxygenation, computed based on central tendency (mean), variability (standard deviation) and signal complexity (multivariate multiscale entropy). 25 older adults (71-81 years of age) completed two tasks of executive functions while undergoing assessment using functional near infrared spectroscopy. Time-varying covariation models were employed to estimate the effects of cerebral oxygenation on behavioural performance, as well as the moderating effects of age and fall status. Findings suggest that mean and variability are differentially associated with behavioural performance and are increased in older adults at greater fall risk. Whereas mean based computations were positively associated with more accurate and faster responding, variability based computations were primarily associated with faster responding only and occurred in non-overlapping regions of prefrontal cortex. Future studies of neural variability may consider examining within- and between-person factors and operationalizing signal complexity in cerebral oxygenation over longer time periods to examine its effects over multiple time scales.
Graduate
drewh@uvic.ca

APA, Harvard, Vancouver, ISO, and other styles

44

Chu, Shiao-Chiang, and 朱孝強. "Use Multiscale Cross-Approximate Entropy to analysis Bilateral Fingertips Photoplethysmographic Pulse of Middle-to-Old Aged Individuals with or without Type 2 Diabetes." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/93w4m2.

Full text

Abstract:

碩士
國立東華大學
電機工程學系
105
Multiscale cross-approximate entropy (MCAE) is a method to calculate the complexity of different signals series. Our research will use above-mentioned method to analysis photoplethysmographic (PPG) pulse amplitudes of the middle-to-old-aged population with or without type 2 diabetes. Hoping the result can evaluate the glycemic status and detect subtle vascular disease in type 2 diabetes. Our laboratory is used to using multiscale sample entropy (MSE) to have complexity of single signal. The past research about Physiological complexity Mainly focused on the quantification of the complexity of Electrocardiography(ECG) signals. So I choose the Non-invasive signal, photoplethysmographic (PPG) pulse amplitudes of bilateral fingertips to analysis by MCAE, and compared with MSE result. I judgment with or without type 2 diabetes by fasting glucose≤ 126 mg/dL or glycated hemoglobin (HbA1c)> 6.5%, and separate the population in three group. From a middle-to-old aged population free of prior cardiovascular disease, we selected the unaffected (no type 2 diabetes, n = 36), the well-controlled diabetes (glycated hemoglobin (HbA1c) < 8%, n = 30), and the poorly- controlled diabetes (HbA1c> 8%, n = 26) groups. I record the populations baseline and parameters relate to arteriosclerosis. I found MCAELS has correlation with HbA1c(r = -0.390 p= 0.001). I also compare the MCAE result with left hand fingertip pulse amplitudes analyzed by Multiscale sample entropy (MSE) in same group. MCAELS is also have better present(Group1 v.s. Group2, p=0.002; Group2 v.s. Group3, p= 0.045; Group1 v.s. Group3, p< 0.001)than large-scale MSE, LMSELS (Group1 v.s. Group2, p=0.014 ; Group1 v.s. Group3, p=0.025). In the future, I hope MCAE can develop to a new index to evaluate the arteriosclerosis and detect subtle vascular disease in type 2 diabetes. Combine to personal device to achieve take care of personal health at any time and effect of prevent disease.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Multiscale Entropy'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles