Thesis (Ph. D.)--University of Rhode Island, 2004. / Typescript. Includes bibliographical references (leaves 105-107).

Thesis (M.S.)--Michigan State University. Dept. of Electrical and Computer Engineering, 2008. / Title from PDF t.p. (viewed on Aug. 7, 2009) Includes bibliographical references (p. 58-59). Also issued in print.

Thesis (Ph. D.)--Brigham Young University. Dept. of Electrical and Computer Engineering, 2007. / Includes bibliographical references (p. 161-167).

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 107-110). Also available on the World Wide Web.

Thesis (Ph. D.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains ix, 131 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 121-131).

Thesis (M.S.)--Montana State University--Bozeman, 2005. / Typescript. Chairperson, Graduate Committee: Vic A. Cundy. Includes bibliographical references (leaf 80).

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Roger T. Bonnecaze. Vita. Includes bibliographical references.

The objective of this work is to offer a new method of evaluation using the corporal and thoracic bioimpedance of pre-term neonate with Respiratory Discomfort Syndrome, submitted or not to the invasive mechanical ventilation. Thirty pre-term neonates with Respiratory Discomfort Syndrome were evaluated. They were admitted interned in the newborn intensive therapy unit of Hospital Universitário Evangélico de Curitiba (HUEC) from August to November of 2004. The percentage average of the gestational age in both groups was 32 weeks and the weight was 1250g. The newborn were divided into two groups, group A (15 newborns), with Respiratory Discomfort Syndrome of medium to moderate clinical repercussion, needing the invasive ventilator support. Group B (15 newborn) with light level of Respiratory Discomfort, without the need of ventilator support. The newborn of both groups were evaluated according to the Silverman-Andersen report. Which average in group A was 7 and in group B was 3. Five time speed measurement of subjects of group A were analyzed in the statistical analyses, and they were compared to an unique observation of group B. On the first measurement made in group A, it was noticed a low resistance both corporal (410) and thoracic (32,53) relative to group B. where the percentage average was 595 in the corporal resistance and 46,13 in the thoracic one. In the capacitive reactance it was noticed in the first analyses an inversely proportional behavior, and an increasing in the capacitive reactance for both corporal and thoracic in group A related to group B. As long as the newborns in group A improved clinically, a tendency in increasing the resistance values both corporal and thoracic was observed, correlating with the ventilator support removal. The opposite occurred in the capacitive reactance, both corporal and thoracic. So, the evaluation through the corporal bioimpedance in this work got statistically significant results, and it can be used as a method of evaluation improving the clinical diagnosis of the patient. / O objetivo deste trabalho é propor um novo método de avaliação através da bioimpedância corporal e torácica em recém-nascidos pré-termo com Síndrome do Desconforto Respiratório, submetidos ou não á ventilação mecânica invasiva. Foram avaliados trinta neonatos pré-termos com Síndrome do Desconforto Respiratório, internados na unidade de Terapia Intensiva Neonatal (UTIN) do Hospital Universitário Evangélico de Curitiba (HUEC), no período de agosto à novembro de 2004. A média da idade gestacional de ambos os grupos foi de 32 semanas e o peso de 1250g. Os recém-nascidos (RN) foram divididos em dois grupos, grupo A (15 neonatos), Síndrome do Desconforto Respiratório de média a moderada repercussão clínica, necessitando de suporte ventilatório invasivo. Grupo B (15 neonatos) Grau leve de Desconforto Respiratório, sem necessidade de suporte ventilatório. Os neonatos dos dois grupos foram avaliados conforme o boletim de Silverman-Andersen, a média percentual no grupo A foi de 77 e no grupo B de 3. Na análise estatística foram analisados cinco momentos do grupo A e comparado esses momentos com uma única observação do grupo B. Nos primeira mensuração realizada no grupo A, observa-se uma resistência tanto corporal (410 Ω) e torácica (32,53 Ω), baixa em relação a obtida no grupo B, onde a média percentual foi de 596 Ω, na resistência corporal e na torácica de 46,13 Ω. Na reatância capacitiva observa-se na primeira análise um comportamento inversamente proporcional, ocorrendo um aumento na reatância capacitiva tanto corporal como torácica no grupo A em relação ao grupo B. A medida que o neonato do grupo A, melhora clinicamente observa-se uma tendência ao aumento de valores de resistência tanto corporal com a torácica, correlacionada com a retirada da prótese ventilatório. Ocorrendo o inverso com a reatância capacitiva tanto corporal como torácica. Portanto, a avaliação através da bioimpedância corporal neste trabalho obteve resultados estatisticamente significativos podendo ser utilizada como um método de avaliação, enriquecendo o diagnóstico clínico do paciente.

De plus en plus d’applications reposent sur l’utilisation des batteries, que cela soit dans le domaine des transports, du smart grid ou des objets connectés. Par conséquent, l’étude des batteries est devenue une problématique majeure. Une batterie est un système électrochimique complexe qui dépend de nombreux paramètres et dont les performances déclinent avec le temps. Ainsi le développement d’un système de gestion efficient de la batterie (battery management system BMS) pour éviter les dégradations, étendre la durée de vie et optimiser son utilisation est une priorité. Un moyen d’obtenir une représentation intéressante de l’état présent de la batterie est d’estimer son impédance électrochimique. Cette thèse développe des techniques d’identification temps-fréquence de cette impédance, qui peuvent facilement être embarquées dans un véhicule ou un autre appareil. La première méthode développée permet non seulement une estimation précise de l’impédance, mais aussi un suivi de son évolution temporelle contrairement aux techniques classiques de spectroscopie d’impédance électrochimique. Cette méthode basée sur la transformée de Fourier repose sur un moyennage local récursif contrôlé par un seul paramètre. Celui-ci gouverne un compromis entre les performances de l’estimation et celles de la pour- suite. La capacité de cette méthode à estimer l’impédance au cours du temps est d’abord démontrée sur un simulateur, puis sur une batterie Lithium ion, sur laquelle une étude de répétabilité est réalisée, et enfin appliquée pour suivre l’évolution de l’impédance de la batterie d’un drone en cours de vol. La seconde méthode basée sur la transformée en ondelettes est développée afin de répondre à la problématique des phénomènes de longue dépendance telles que les réactions de diffusion limitée qui apparaissent dans les batteries. Des modèles de batteries reposant sur des circuits électriques équivalents incluent souvent des éléments à phase constante (constant phase element CPE) pour prendre en compte ces phénomènes. La méthode basée sur la transformée de Fourier est comparée à celle basée sur le transformée en ondelettes sur un simulateur de CPE grâce à une procédure de Monte Carlo. L’approche par les ondelettes avec son pavage temps-fréquence irrégulier apparaît comme une méthode particulièrement adaptée à ces phénomènes. A partir de l’impédance, quatre différents indicateurs de l’état de la batterie sont ensuite développés. L’estimation de l’état de charge via un filtre de Kalman étendu dans le contexte de l’étude de la batterie du drone pendant un vol est d’abord effectuée. Cette thèse s’intéresse aussi à l’estimation des paramètres du CPE liés aux phénomènes de longue dépendance. Un estimateur de la puissance maximale disponible généralement utilisée dans le secteur des transports est élaboré à partir de la réponse impulsionnelle de la batterie. Afin de prévenir du risque d’emballement thermique l’estimation de l’impédance est utilisée pour connaître l’état thermique de la batterie en estimant sa température interne. / More andmore applications rely on batteries, for instance in the field of transport, of smart grid, of connected objects. Therefore, the development of battery has become a crucial issue. Unfortunately, a battery is a complex electrochemical system which depends of many parameters and whose performance deteriorates over time. Thus the development of an efficient battery management system (BMS) to avoid damages, to extend lifespan and to optimize the use of batteries is a priority. One way to obtain interesting information representative of the present state of the battery is to estimate its electrochemical impedance. This thesis presents time frequency impedance identification methods which can be easily embedded in vehiclesor nomad devices.The first developed method not only allows an accurate impedance estimation but also a tracking of its temporal evolution contrary to classical electrochemical spectroscopy techniques. This method based on Fourier transformrelies on recursive local average controlled by a single parameter, managing a trade-off between tracking and estimation performance. The ability of the method to monitor the impedance over time is demonstrated on a simulator, then on a real lithium ion battery, on which a repeatability study is carried out, and finally applied to follow the impedance evolution of a drone battery during a flight.The second method based on wavelet transformis developed to deal with long-range dependence phenomena such as ion diffusion-limited reactions which occur in the battery. Battery models using electrical equivalent circuit often include Constant Phase Elements (CPE) to account for these phenomena. After compared wavelet to Fourier method on a CPE simulator thanks to a Monte Carlo procedure, the wavelet approach and its irregular time-frequency tiling appears to be an interesting method, specificaly for its minor bias error.To develop a powerful BMS, different battery indicators or parameters are then estimated from the impedance to be able to follow the state of the battery in real time and avoid damages. To optimise the use of battery the state of charge, the CPE parameters, the maximum available power and the internal temperature of the cell are estimated.

Two failure modes related to water management in Proton Exchange Membrane fuel cells (dehydration and flooding) were investigated using electrochemical impedance spectroscopy as a diagnosis tool. It was hypothesised that each failure mode corresponds to changes in the overall stack impedance that are observable in different frequency ranges. This hypothesis was corroborated experimentally. The experimental implementation required new testing hardware and techniques. A four-cell stack capable of delivering individually conditioned reactants to each cell was designed, built, tested, and characterised under a variety of operating conditions. This stack is the first reported prototype of its type. The stack was used to perform galvanostatic, impedance measurements in situ. The measurements were made at three different temperatures (62, 70 and 80°C), covering the current density range 0.1 to 1.0 A cm−2 , and the frequency range 0.1 to 4 × 105 Hz. The recorded data represent the first reported set of measurements covering these ranges. The failure modes were simulated on individual cells within the stack. The effects on individual cell and stack impedance were studied by measuring the changes in stack and cell impedances under flooding or dehydration conditions. Dehydration effects were measurable over a wide frequency range (0.5 to 105 Hz). In contrast, flooding effects were measurable in a narrower frequency range (0.5 to 102 Hz). Using these results, separate or concurrent impedance measurements in these frequency ranges (or narrow bands thereof) can be used to discern and identify the two failure modes quasi-instantaneously. Such detection was not possible with pre-existing, do techniques. The measured spectra were modelled by a simple equivalent circuit whose time constants corresponded to ideal (RC) and distributed (Warburg) components. The model was robust enough to fit all the measured spectra (for single cells and the stack), under normal and simulated-failure conditions. Approximate membrane conductivities were calculated using this model. The calculations yielded a range from 0.04 to 0.065 S cm−1 (under normal humidification), and conductivities that deviated from these nominal range under flooding or dehydrating conditions. The highest conductivity value (was ∼0.10 S cm−1) was measured under flooding conditions at j = 0.4 A cm−2. The lowest conductivity (∼0.02 S cm−1) corresponded to a dehydrated cell at j = 0.1 A cm−2. These values fall within the ranges of published data for modern proton exchange membranes. The phenomenological and numerical results reported in this work represent the first demonstration of these techniques on a PEMFC stack under real operating conditions. They are also the basis of ongoing research, development, and intellectual property protection. / Graduate