Thesis. 1977. M.S.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERO. / Includes bibliographical references. / M.S.

A hipoventilação secundária ao procedimento anestésico é comum na prática anestésica, e, sendo assim, o emprego de técnicas de ventilação mecânica é adotado como forma de minimizar e/ou evitar os efeitos deletérios da hipoventilação. Porém, o uso de ventiladores mecânicos não é isento de risco, e atelectasias podem se formar mesmo quando são utilizados. Para análise em tempo real do pulmão, a técnica de tomografia por impedância elétrica vem sendo empregada em conjunto com outros meios de monitoração, tendo se demonstrado um meio útil de avaliação da ventilação pulmonar de maneira não invasiva, passível de ser utilizada à beira do leito e sem emissão de radiação. Estudos utilizando o tomógrafo de impedância elétrica em cães são escassos. O objetivo desse trabalho foi avaliar a ventilação de cães submetidos à anestesia inalatória e à ventilação mecânica utilizando a técnica de tomografia por impedância elétrica. Foram utilizados onze cães com peso superior a 16 kg e classificados como baixo risco anestésico (ASA I ou II). Os animais receberam acepromazina e meperidina como medicação pré-anestésica, propofol como indutor e isofluorano na manutenção da anestesia. Foram mantidos em ventilação mecânica controlada a pressão, com FiO2 de 0,6 e pressão de pico de 10 cmH2O durante os primeiros 90 minutos de anestesia. Foram então realizadas manobras de recrutamento alveolar e instituição de pressão positiva ao final da expiração (PEEP) de 5 cmH2O, e os animais foram avaliados por mais 35 minutos. Os parâmetros foram avaliados 30, 60 e 90 minutos após a indução da anestesia e 5 e 35 minutos após o recrutamento e instituição da PEEP. Apesar de não ter havido diferença estatisticamente significativa nos parâmetros de oxigenação e distribuição da ventilação, foi visível a melhora clínica e nas curvas de oxigenação e impedância. As curvas de impedância geradas a partir dos dados obtidos pelo tomógrafo de impedância elétrica acompanharam as curvas de melhora na oxigenação. O fato de, no estudo, terem sido utilizados animais hígidos e submetidos à ventilação mecânica e FiO2 de 0,6 desde o início pode ter contribuído para não ter havido melhora estatisticamente significativa, embora clinicamente visível. As manobras de recrutamento utilizadas também foram conservadoras em comparação aos outros trabalhos realizados. Infere-se que, se utilizássemos animais doentes e com FiO2 de 1, poderíamos ter obtido um grau maior de atelectasias nos primeiros 90 minutos de anestesia e/ou, se tivéssemos utilizado manobras de recrutamento menos conservadoras, poderíamos ter obtidos melhora estatisticamente significativa após as manobras e instituição da PEEP. A tomografia de impedância elétrica parece ser um bom meio de monitoração do pulmão em tempo real em cães submetidos à anestesia inalatória. / Hypoventilation secondary to anesthesia is common and, therefore, the use of mechanical ventilation techniques is adopted in order to minimize and/or prevent the deleterious effects of hypoventilation. However, the use of mechanical ventilators has risks, and atelectasis can develop even when they are used. For real-time analysis of the lung, the technique of electrical impedance tomography has been used in conjunction with other means of monitoring, having demonstrated to be useful for assessing pulmonary ventilation in a noninvasively way, and also can be used at the bedside and without radiation emission. There are not many studies using electrical impedance tomography in dogs. The aim of this study was to evaluate the ventilation of dogs subjected to inhalation anesthesia and mechanical ventilation using the technique of electrical impedance tomography. We used eleven dogs weighing more than 16 kg and classified as low anesthetic risk (ASA I or II). The animals were premedicated with acepromazine and meperidine, anesthesia was induced with propofol and maintained with isoflurane. Ventilation was then instituted with FiO2 of 0.6 and peak pressure of 10 cm H2O during the first 90 minutes of anesthesia. Alveolar recruitment maneuvers were realized and pressure positive end- expiratory pressure (PEEP) of 5 cmH2O was initiated. The animals were evaluated for more 35 minutes then. The parameters were measured at 30, 60 and 90 minutes after induction of anesthesia and 5 and 35 minutes after recruitment. Although there was no statistically significant difference in the parameters of oxygenation and ventilation distribution, clinical improvement was visible as was the oxygenation and impedance curves. The impedance curves generated from the data obtained with the electrical impedance tomograph followed the improvement in oxygenation curves. The fact that in this study we used healthy animals undergoing mechanical ventilation with FiO2 of 0.6 right from the beginning, may have contributed to no improvement statistically significant but clinically visible. Recruitment maneuvers used were also conservative in comparison to other papers. We think that, if we used animals and patients with FiO2 of 1, we could have obtained a higher degree of atelectasis in the first 90 minutes of anesthesia and/or, if we had used less conservative recruitment maneuvers, we could have obtained statistically significant improvement after maneuvers and institution of PEEP. The electrical impedance tomography seems to be a good means of real time monitoring the lung of dogs undergoing inhalation anesthesia.

L’objectif de cette thèse est de développer la caractérisation et le diagnostic non destructif de microbatteries « tout solide » par spectroscopie d’impédance électrochimique. Ces travaux s’appuient sur des microbatteries commerciales EnFilmTM EFL700A39, basées sur une architecture lithium métal Li/LiPON/LiCoO2. La caractérisation unitaire des couches actives, constituant ces microbatteries, a permis d’une part, d’identifier les principales propriétés de transport des ions Li+ dans l’électrolyte solide, et d’autre part, a permis de mettre en avant la présence de zones plus ou moins conductrices dans la couche active LiCoO2, pouvant engendrer des limitations électroniques et/ou ioniques lors du fonctionnement de la microbatterie. L’étude des microsystèmes complets par spectroscopie d’impédance électrochimique a ensuite été effectuée en fonction du taux de lithiation de l’électrode positive, du nombre de cycles, et du vieillissement calendaire de la microbatterie. Les résultats obtenus ont donné naissance à un circuit électrique équivalent permettant de modéliser le comportement (souvent indépendant) des différentes couches actives durant l’utilisation d’une microbatterie. Cette modélisation permet en outre de cibler les origines éventuelles de défaillances, soit après la fabrication, soit au cours du vieillissement d’une microbatterie. Les travaux additionnels effectués sur des systèmes lithium free (LiCoO2/LiPON/Cu) révèlent, quant à eux, une forte interaction électrochimique entre le lithium et le collecteur de cuivre (partiellement oxydé) et mettent en évidence l’importance capitale des premiers cycles de la cellule pour ses performances ultérieures / The goal of this work is to develop characterization and non-destructive diagnosis of all-solid-state lithium microbatteries, essentially by means of electrochemical impedance spectroscopy. This work is based on commercial microbatteries EnFilmTM EFL700A39, built with the lithium metal architecture Li/LiPON/LiCoO2. Firstly, the elemental characterization of active layers allowed us to identify the main properties of the ionic motion in the solid electrolyte layer. Secondly, characterization of the positive electrode (LiCoO2) revealed the existence of more or less conductive areas inside the layer. Theses areas can cause ionics or electronics limitations during battery operation. The study of the entire microsystems by electrochemical impedance spectroscopy was then performed according to lithiation rate (SOC), number of cycles, and battery aging. The results obtained allowed the building of an electrical equivalent circuit for modeling the behaviour of the different active layers of a microbattery in use. This model also allows targeting the origins of any failures after manufacturing or upon microbattery aging. Additional works on lithium free systems (LiCoO2/LiPON/Cu) reveals a strong electrochemical interaction between in situ deposited lithium and copper current collector (partially oxidized) and highlight the critical importance of the very first cycles of the cell for subsequent performance

Mechanical ventilation is vital for the treatment of patients in respiratory intensive care and can be life saving. However, the risks of regional pressure gradients and over-distension must be balanced with the need to maintain function. For these reasons mechanical ventilation can benefit from the regional information provided by bedside imaging such as electrical impedance tomography (EIT). In this thesis we develop and test methods to retrieve clinically meaningful measures of lung function from EIT and examine the feasibility of closing the feedback loop to enable EIT-guided control of mechanical ventilation. Working towards this goal we develop a reconstruction algorithm capable of providing fast absolute values of conductivity from EIT measurements. We couple the resulting conductivity time series to a compartmental ordinary differential equation (ODE) model of lung function in order to recover regional parameters of elastance and airway resistance. We then demonstrate how these parameters may be used to generate optimised pressure controls for mechanical ventilation that expose the lungs to minimal gradients of pressure and are stable with respect to EIT measurement errors. The EIT reconstruction algorithm we develop is capable of producing low dimensional absolute values of conductivity in real time after a limited additional setup time. We show that this algorithm retains the ability to give fast feedback on regional lung changes. We also describe methods of improving computational efficiency for general Gauss-Newton type EIT algorithms. In order to couple reconstructed conductivity time series to our ODE model we describe and test the recovery of regional ventilation distributions through a process of regularised differentiation. We prove that the parameters of our ODE model are recoverable from these ventilation distributions apart from the degenerate case where all compartments have the same parameters. We then test this recovery process under varying levels of simulated EIT measurement and modelling errors. Finally we examine the ODE lung model using control theory. We prove that the ODE model is controllable for a wide range of parameter values and link controllability to observable ventilation patterns in the lungs. We demonstrate the generation and optimisation of pressure controls with minimal time gradients and provide a bound on the resulting magnitudes of these pressures. We then test the control generation process using ODE parameter values recovered through EIT simulations at varying levels of measurement noise. Through this work we have demonstrated that EIT reconstructions can be of benefit to the control of mechanical ventilation.

Made available in DSpace on 2014-06-11T19:22:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-12Bitstream added on 2014-06-13T19:07:27Z : No. of bitstreams: 1 vulcano_dsb_me_botfm.pdf: 1165851 bytes, checksum: ae1702dfaee6063d32a01859daa38f20 (MD5) / A doença hepática crônica influencia direta e indiretamente o estado nutricional do paciente, sendo a desnutrição bastante prevalente nesta população. As causas da desnutrição são multifatoriais, relacionadas à alteração na ingestão, na absorção e no metabolismo dos macro e micronutrientes. O diagnóstico nutricional torna-se difícil, pois, não existe um método considerado padrão-ouro e os métodos disponíveis podem não ser fidedignos pela influência da própria doença no resultado. O objetivo do trabalho foi avaliar os indicadores do estado nutricional e a composição corporal dos pacientes portadores de cirrose hepática e relacioná-los com o sexo, a etiologia e a gravidade da doença hepática. Os indicadores nutricionais avaliados foram os antropométricos (Índice de Massa Corpórea específico para pacientes cirróticos, dobras cutâneas e circunferências), os funcionais (dinamometria e espessura do músculo adutor do polegar), a avaliação nutricional subjetiva global e os laboratoriais (albumina, hemoglobina, hematócrito e contagem total de linfócitos). Para a avaliação da composição corporal foi utilizada a bioimpedância elétrica unifrequencial (BIA) que mensurou a resistência (R), a reactância (Xc), o ângulo de fase (AF) e a massa celular corpórea (MCC). A gravidade da doença hepática foi estimada pelos critérios de Child-Pugh e pelo Meld (The model end-stage liver disease). Os indicadores do estado nutricional foram dicotomisados em: desnutrição e sem desnutrição ou com depleção e sem depleção. Os pacientes cirróticos de etiologia alcoólica apresentaram maior depleção em todos os parâmetros antropométricos, funcionais e na avaliação nutricional subjetiva global (ANSG), sendo estatisticamente significante para Circunferência do Braço (CB), Circunferência Muscular do Braço (CMB) e ANSG... / The chronic hepatic disease directly and indirectly influences on patient’s nutritional status and malnutrition is highly prevalent in this population. The causes of malnutrition are multifactorial, related to alterations on ingestion, absorption and metabolism of macro and micronutrients. The nutritional diagnosis is difficult, because there isn’t a gold standard method, and available methods are not reliable, once the disease itself interferes in the result. The objective of the work was to appraise nutritional status indicators and body composition of cirrhotic patients treated in the nutrition first aid posts of Faculdade de Medicina de Botucatu – UNESP, and relate them to gender, etiology and severity of the liver disease. The nutritional indicators appraised have been the anthropometrical (specific body mass index for cirrhotic patients, skinfolds and circumferences), the functional (dynamometry and thickness of the adductor pollicis muscles), the Subjective Global Assessment of Nutritional Status (SGA) and the laboratorial (albumin, hemoglobin, hematocrit, lymphocytes total count). On the appraisement of body composition, unifrequency bioelectrical impedance analysis (BIA) has measured resistance (R), reactance (Xc), phase angle (PA) and body cell mass (BCM). The severity of the liver disease has been estimated by the Child-Pugh score and by Meld (The Model end-stage liver disease). The nutritional status indicators have been dichotomized as following: malnutrition and without malnutrition, or with depletion and without depletion. Cirrhotic patients with alcoholic etiology have exhibited more depletion in all the anthropometrical and functional parameters and in the Subjective Global Assessment of Nutritional Status (SGA) and they have been statistically relevant for Arm Circumference (AC), Arm Muscular Circumference (AMC) and SGA... (Complete abstract click electronic access below)

There is a critical need for inspection and condition monitoring of high temperature critical components such as pipelines and welds in electrical power generation and other plants operating at temperatures as high as 580°C. The high temperatures and pressures experienced in these pipelines, particularly for ageing plants lead to creep, fatigue and corrosion type defects. Safety of these plants is of paramount importance, and regular maintenance is carried out during planned outages at ambient temperatures. Ultrasonic non-destructive testing can be used to detect defects in the weld at ambient temperatures. However, at high operational temperatures, this technique cannot be applied due to the lack of high temperature transducers. This research has achieved significant advances towards enabling ultrasonic inspection and condition monitoring of high temperature critical points, by developing an ultrasonic transducer around an advanced piezoelectric single crystal material, called Gallium Orthophosphate (GaPO4), which can operate at the required temperature of 580°C. Based on its reported piezoelectric and other properties, and its commercial availability, GaPO4 was chosen as a candidate active material for application in a prototype high temperature transducer. In a series of confidence building tests with the selected piezoelectric material (electrical characterisation via the impedance method), it has been demonstrated that the GaPO4 piezoelectric elements are stable when subjected to 580°C for more than 600 hours. Ultrasonic thickness gauging has shown that GaPO4 works as a functional transducer generating and receiving ultrasound waves at 580°C for at least 360 hours. Furthermore, the sensitivity of the GaPO4 transducer to detect defects with simple geometry was successfully tested through measurements on steel blocks containing artificial defects (side-drilled holes) up to the same high temperatures. Based on the characterisation results from the impedance and ultrasonic measurements, a prototype ultrasonic transducer for operation at high temperatures has been designed and manufactured. The new ultrasonic transducer was tested in a laboratory environment using a steel calibration block, high temperature couplant, SONO 1100, and an electric furnace. In the range from ambient temperatures up to the target of 580°C, the ultrasonic transducer kept a signal-to-noise (SNR) level sufficiently high, above the threshold of 6 dB, which is high enough for practical non-destructive testing and condition monitoring.

Este trabalho analisa a qualidade dos combustíveis derivados de petróleo através de suas propriedades acústicas, visando assim um monitoramento contínuo e instantâneo. Analisa a variação da impedância acústica da gasolina com acréscimo de vários componentes como: tolueno, óleo diesel, querosene e álcool anidro. Os resultados obtidos mostram uma variação significativa embora não linear da impedância acústica nos combustíveis derivados de petróleo com acréscimo de tais substâncias. / This work is related with research project focused on the development of low cost and robust quality monitoring equipment and methods, suitable for application in the production of petrochemical compounds. The main objective of this work is to assess the quality of automotive gasoline through the analysis of its acoustic properties. More specifically, pure gasoline\'s acoustic impedance (defined as the product between its density and the velocity of propagation of an acoustic wave) is analyzed with respect to the addition of toluene, kerosene, ethanol and diesel fuel. Results show that the acoustic impedance is sensitive to the addition of such components, although this relation may be non-linear in some cases.

Este trabalho analisa a qualidade dos combustíveis derivados de petróleo através de suas propriedades acústicas, visando assim um monitoramento contínuo e instantâneo. Analisa a variação da impedância acústica da gasolina com acréscimo de vários componentes como: tolueno, óleo diesel, querosene e álcool anidro. Os resultados obtidos mostram uma variação significativa embora não linear da impedância acústica nos combustíveis derivados de petróleo com acréscimo de tais substâncias. / This work is related with research project focused on the development of low cost and robust quality monitoring equipment and methods, suitable for application in the production of petrochemical compounds. The main objective of this work is to assess the quality of automotive gasoline through the analysis of its acoustic properties. More specifically, pure gasoline\'s acoustic impedance (defined as the product between its density and the velocity of propagation of an acoustic wave) is analyzed with respect to the addition of toluene, kerosene, ethanol and diesel fuel. Results show that the acoustic impedance is sensitive to the addition of such components, although this relation may be non-linear in some cases.

Student Number : 0009815Y - PhD thesis - School of Physics - Faculty of Science / Determining the properties of composites and how these relate to those of the components and the microstructure is extremely useful as it enables the understanding of existing materials and the design of new materials with a variety of applications. However, the link between the ac conductivity data and the microstructure and composition of the composite is not a simple one. Simulations of binary composites are presented which show that from relatively simple component properties arise complex composite properties. Accurate identi¯cation of the components of composites, using characteristic frequencies, is demonstrated for simulated and actual experimental data. The Maxwell-Wagner and Brick Layer Models, which are often applied beyond the range of their original derivation, are found to consistently ¯t the data of yttria-stabilized zirconia ceramics measured at various tempera- tures. The results from ¯tting single crystal and polycrystalline sample data indicate that accurate modeling of the properties of the polycrystalline sam- ples requires more theoretical work on the conduction mechanisms in single crystals and the grains of the ceramics. Data from a polyester-resin/silicon system is found to be best ¯tted us- ing the Single Exponent Phenomenological Percolation Equation (SEPPE) with experimentally measured component properties as input. The percola- tion threshold obtained suggests a system where the insulator tends coat the conductor. The results show that, with the actual component properties as input, the SEPPE can be used to qualitatively and semi-quantitatively model and ¯t composite ac conductivity data. Analysis of the ac conductivity of liquid-phase-sintered silicon carbide ce- ramics showed that for this system, the features often observed in the imped- ance spectra are all due to a multi-component grain bondary/binder phase and not the SiC grains. This multi-component grain boundary phase can be ¯tted accurately to the Brick Layer Model, indicating a microstructure where an insulating component coats a more conducting component.

Energy quantities, which are calculated from pressure and particle velocity, yield a great deal of information about acoustic fields. Errors in pressure or particle velocity estimation lead to bias errors the estimation of energy quantities. The bias errors arise from different probe configurations and processing methods. Two processing methods are examined: the traditional method and the recently developed Phase and Amplitude Gradient Estimation (PAGE) method. These two methods are compared to investigate how each estimates pressure and particle velocity and the subsequent bias errors in a plane wave, standing wave, and spherical spreading wave field. Analytical expressions are derived for the energy quantity estimation using ideal one-dimensional probes. A simulation of the field from a baffled circular piston and measurements using ideal two-dimensional probes is computed. Compared to the traditional method, the PAGE method significantly extends the range of frequencies for which the results are accurate. It is found that a probe with a center microphone significantly reduces the estimation error and extends the usable range of frequencies. The PAGE method with unwrapping, perfectly matches the analytical results for plane waves, while the traditional method is only good at wavelengths that are large compared to the probe size. Furthermore, the PAGE method has a constant bias error in spherical wave fields due to the 1/r decrease in pressure. The traditional method has a frequency dependent bias error that is much worse at higher frequencies. Lastly, the PAGE method has the same or worse error for the standing wave. As an application of energy quantities, acoustic intensity is used to develop an equivalent source model for jet noise from an F-22 at military and afterburner engine conditions. An optimization is used to find the best-matching wavepacket model for measured intensity vectors. The results are compared to another intensity method of estimating the source region and source directivity, and the two methods have good agreement.