Made available in DSpace on 2014-10-09T12:26:44Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:08Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Les fluctuations du taux de dégagement de chaleur sont souvent responsables d’intensification des flux thermiques aux parois, de vibrations et d’émissions sonores qui peuvent éventuellement dégénérer en instabilités thermo-acoustiques auto-entretenues. Ces phénomènes instationnaires dégradent les performances des foyers, provoquent un vieillissement prématuré de certains éléments de la chambre de combustion, voire des dégâts plus importants sur l’installation. Ces perturbations sont cependant difficiles à mesurer dans les foyers car il n’existe pas de diagnostic qui permette d'accéder directement au taux de dégagement de chaleur. L’objectif de ce travail est d'explorer deux alternatives aux solutions existantes pour accéder aux fluctuations du taux de dégagement de chaleur avec une bonne résolution temporelle. Ces nouvelles méthodes sont testées dans des configurations génériques parfaitement prémélangées pour des écoulements laminaires. La première méthode est une technique acoustique, qui repose sur la détermination du temps de vol d’ondes ultrasonores qui traversent l’écoulement. Les fluctuations du temps de vol de ces ondes sont utilisées pour détecter des perturbations de la largeur des gaz brûlés le long du chemin acoustique. Cette information permet de reconstituer les fluctuations du taux de dégagement de chaleur dans des flammes prémélangées. Les premières validations de cette méthode sont présentées pour des flammes en l'absence de perturbation externe lorsqu'elles présentent une instabilité de type Kelvin-Helmholtz pilotée par les phénomènes de flottabilité du panache des gaz brûlés. Des mesures sont ensuite conduites pour des flammes soumises à des modulations harmoniques de l'écoulement. Les données obtenues dans ces configurations sont comparées à des mesures optiques ainsi qu'à des prévisions analytiques. La seconde méthode est une technique optique utilisant un système d’interférométrie laser Doppler permettant de déterminer les fluctuations de densité intégrées le long du chemin optique. On montre dans un premier temps que les perturbations de densité sont principalement causées par des fluctuations du taux de dégagement de chaleur lorsque les flammes sont confinées. Un lien est établi pour reconstituer les perturbations du taux de dégagement de chaleur exploitant le signal de l'interféromètre. La technique est validée pour des flammes pulsées pour différentes richesses et débits. Les données obtenues sont comparées à des mesures reposant sur la chimiluminescence de la flamme. Un bon accord est obtenu pour des modulations harmoniques de l'écoulement à différentes fréquences et niveaux de perturbation. Ce travail permet de valider le principe de ces deux techniques pour détecter les perturbations du taux de dégagement de chaleur lorsque l'accès optique à la zone de combustion est réduit et lorsque des informations quantitatives résolues temporellement sont nécessaires. / Heat release rate disturbances are the sources of additional thermal stresses, direct and indirect combustion noise and undesirable vibrations. In extreme cases, these perturbations may even cause destructive combustion instabilities. These quantities are difficult to measure in practical burners. The objective of this work is to develop two alternative diagnostics to measure heat release rate fluctuations in unsteady flames. These techniques are validated in generic configurations for perfectly premixed laminar flames. The first method is an acoustic technique, which is based on the measurement of the travel time of ultrasonic waves through the flames. Fluctuations of the sound propagation time transmission through unsteady flames are used to estimate perturbations in the burned gases width along the acoustic path. This information is then used to reconstruct heat release rate fluctuations. This technique is validated in the cases of unstable laminar premixed flames driven by buoyancy forces and for flames submitted to harmonic flow velocity modulations. Analytical expressions are derived linking fluctuations in heat release rate and disturbances of the sound travel time. Measurements made with this acoustic technique are compared with optical detections based on the flame chemiluminescence and with predictions from an analytical model. Good agreements are obtained between these different methods validating the proposed technique. The second method envisaged is an optical technique based on a Laser Interferometric Vibrometer used to measure integrated density perturbations along the optical path of a laser beam. It is shown that density disturbances along this path result mainly from heat release rate fluctuations when the flames are confined. A link is established to reconstruct heat release rate disturbances from the signal of the interferometer. The technique is validated in the case of pulsated laminar premixed flames. Measurements are compared to line-of-sight integrated chemiluminescence emission measurements. A good agreement is obtained for harmonic flow modulations at different forcing frequencies and perturbation levels for flames operating at different flow conditions. This work validates the principle of this alternative technique for detecting heat release rate perturbations.

Os ensaios não destrutivos visam avaliar um elemento sem gerar danos a ele com a técnica empregada. Um tipo de ensaio não destrutivo é o método da velocidade do pulso de ondas ultrassônicas. Este método é comumente utilizado para determinar propriedades elásticas de um dado material e verificar danos no interior dos elementos estudados. Outra aplicação do ultrassom é a medição do nível de tensão num material por meio da propagação das ondas ultrassônicas, tendo como base a teoria da acustoelasticidade. Entretanto, o uso do ultrassom para esta finalidade ainda é pouco difundido, principalmente na aplicação em estruturas de concreto. Este trabalho teve como objetivo estudar a possibilidade de medir tensões em estruturas de concreto com o uso do ultrassom. Para tanto, foram realizados ensaios de compressão uniaxial em prismas de concreto. Durante os ensaios, foram emitidas ondas ultrassônicas nos elementos para cada nível de tensão aplicada no material. A partir destes ensaios, foi feito um estudo do comportamento acustoelástico do concreto. Verificou-se que as velocidades das ondas ultrassônicas variaram em função da intensidade das tensões normais de compressão existentes nos corpos de prova. Com base na variação das velocidades, os coeficientes acustoelásticos do concreto de cada prisma foram determinados e relacionados com propriedades do concreto. Verificou-se a possibilidade de se estimar o nível mínimo de tensão em determinadas estruturas de concreto a partir do conhecimento de seus coeficientes acustoelásticos. Concluiu-se que é possível estimar tensões em estruturas de concreto utilizando o ultrassom. / Nondestructive tests aim to analyze an element generating no damages. The pulse velocity of ultrasonic waves method is a type of nondestructive test. This method is commonly used to determine elastic properties of materials and to verify damages inside studied elements. Another application for ultrasound is the measurement of stress level in a material by means of propagation of ultrasonic waves. This application is based on the theory of acoustoelasticity. However, the use of ultrasound is still unusual for this purpose, mainly in application in concrete structures. This work intended to study the possibility of measuring stresses in concrete structures with the use of ultrasound. Uniaxial compression tests were performed on concrete prisms. During tests, ultrasonic waves were propagated in elements for each level of applied stress in the material. Then, a study about acoustoelastic behavior of concrete was performed. It was verified that the velocities of ultrasonic waves changed according to the intensity of normal compressive stresses there were in the specimens. Based on the variation of velocities, the acoustoelastic coefficients of concrete were determined for each prism. The coefficients were related with properties of concrete. The possibility of estimating the minimum level of stress in certain structures of concrete from their acoustoelastic coefficients was verified. It was concluded it is possible to estimate stresses in concrete structures using ultrasound.

Made available in DSpace on 2014-10-09T12:26:44Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:08Z (GMT). No. of bitstreams: 0 / O câncer é hoje a segunda maior causa de morte por doenças em vários países, inclusive o Brasil. Excluindo-se o câncer de pele não melanoma, o câncer de próstata é o mais incidente na população, em geral. O tumor de próstata pode ser tratado por diversos métodos, incluindo a braquiterapia, que consiste na colocação de fontes radioativas seladas na forma de sementes, contendo o radioisótopo iodo-125 junto ao tumor. Dessa maneira, a região alvo do tratamento recebe alta dose de radiação, sendo essa dose reduzida sensivelmente nos tecidos circunvizinhos saudáveis. A semente é composta de uma cápsula de titânio selada por meio de soldagem, com 0,8mm de diâmetro externo e 4,5mm de comprimento, contendo em seu interior um fio de prata de 0,5mm de diâmetro, com o iodo-125 adsorvido. Após sua construção, a semente deve ser submetida a um ensaio de estanqueidade, garantindo a ausência de qualquer vazamento de material radioativo. Os principais objetivos deste trabalho foram o estudo e desenvolvimento dos métodos de ensaio de estanqueidade aplicáveis às sementes de iodo-125, propostos pela norma ISO 997820, a escolha do método mais adequado para o processo de produção e a determinação do fluxograma do processo a ser utilizado. Os ensaios realizados excederam a exigência da norma, com a aplicação de ultra-som durante o período de imersão das sementes. Os resultados mostraram a eficácia da aplicação de ultra-som, aumentando muito a detecção de vazamentos de material radioativo. Os melhores resultados foram obtidos utilizando-se água destilada a 20º C com imersão por 24 horas e água destilada a 70º com imersão por 30 minutos. Esses métodos são os escolhidos para serem utilizados durante a produção das sementes. O fluxograma de processo desenvolvido contempla todas as fases do ensaio de estanqueidade, de acordo com a seqüência realizada durante os experimentos. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

M.Tech. / Purpose: This study aims to determine whether adjusting the area of nerve root supply, or adjusting the attachment site of the latissimus dorsi muscle, will have an effect on the latissimus dorsi muscle and to which extend, with regards to strength and electromyographic (sEMG) activity. These effects were evaluated by measuring the latissimus dorsi .muscle strength using a Jamar dynamometer as well as sEMG readings of the latissimus dorsi muscle using a Neuro Trac ETS unit. Readings were taken prior to treatment on the first, third, and fifth consultations. Method: Forty five participants who met the inclusion criteria were stratified in number and gender between three groups of equal size (15 participants each). Group 1 received lower cervical adjustments (C5 - C7), group 2 received lower thoracic and lumbar adjustments (T6 - L5) and group 3 received detuned ultrasound therapy on the latissimus dorsi muscle. Group three served as the control group. Participants were treated four times out of a total of five sessions, over a maximum three week period Procedure: Objective data was collected at the beginning of the first and third session, as well as on the fifth consultation by means of a Jamar dynamometer and a Neuro Trac ETS unit in order to assess the functionality of the latissimus dorsi muscle. Analysis of collected data was performed by a statistician. Results: Statistically significant improvement in the dynamometry readings of both the experimental groups were noted when compared to that of the control group. The results of the sEMG activity were variable. Conclusion: The results show that adjusting the area of nerve root supply as well as adjusting the attachment site of the latissimus dorsi muscle are effective treatment protocols (as demonstrated statistically) in increasing strength of the latissimus dorsi muscle. The results suggest that adjusting the attachment site of the latissimus dorsi muscle is most effective in increasing the strength of the latissimus dorsi muscle. The results of the sEMG activity were variable and there were no evidence supporting the effectiveness of adjusting the area of nerve root supply versus adjusting the attachment site ofthe latissimus dorsi muscle on sEMG activity.

Cette thèse s’est déroulée dans le contexte de l’évaluation non destructive du collage de patches composites employés pour la réparation de structures aéronautiques. Le besoin a été exprimé par la DGA Techniques Aéronautiques (Toulouse). Le travail effectué a consisté en l’exploitation des ondes guidées, de type SH puis Lamb, pour mesurer des caractéristiques mécaniques d'un joint de colle et tenter d’évaluer, de manière non destructive, la qualité du collage. Dans un premier temps, les propriétés viscoélastiques des matériaux assemblés sont déterminées. Elles servent alors de données d’entrée à des modèles, basés sur la méthode SAFE (Semi Analytical Finite Element method), permettant d’obtenir les courbes de dispersion ainsi que les champs des différents modes guidés se propageant le long de l’assemblage collé. Ces simulations numériques permettent alors d’évaluer le potentiel des ondes guidées à caractériser un adhésif. Des mesures expérimentales sont ensuite menées pour confirmer les prédictions numériques. Finalement la résolution d’un problème inverse, qui consiste à évaluer les modules de rigidité de la couche de colle se situant entre une plaque d’aluminium et un patch, est proposée pour établir des pistes d’évaluation non destructive d’un collage répondant au besoin industriel. Cette étude a été financée par la DGA, France. / Repairing of metallic structures using composite patches bonded with an adhesive layer is more and more common in the aeronautic field, and particularly at DGA Techniques Aéronautiques. In order to guarantee the quality of this bond, the sensitivity of ultrasonic guided waves is investigated. Shear-horizontally polarized (SH) waves, and Lamb waves are investigated to infer the stiffness of the adhesive layer. The SAFE method is used to predict the dispersion curves and mode shapes of the different wave modes propagating along the three-layer assembly. Numerical simulations are run for selecting the most appropriate wave modes, i.e. with higher sensitivity to the stiffness of the bond than to other components properties. Experiments are also made for generating-detecting pre-selected SH or Lamb wave modes in order to confirm the numerical predictions. Finally the resolution of an inverse problem, consisting in the evaluation of the stiffness modulus of the bond layer between an aluminium plate and a carbon-epoxy composite patch, at different curing time, is proposed as a contribution to the establishment of possible strategies for bonds testing. This work was supported by DGA, France.

The growth in the extent of applications of composite materials, particularly in commercial products, has been dramatic and carries an implied mandate for effective methods for material quality evaluation. The cost of composite materials dictates that non-destructive test methods be used. At the same time, the nature of composites limits the use of conventional techniques such as radiography , eddy-current or ultrasonics. Recently, a new technique known as the Acousto-Ultrasonic (AU) technique, has been developed and appears to hold promise as a method for the evaluation of composite material quality. Implementation of the AU method is examined using the zeroth moment method developed by Henneke et.al. A new parameter termed as Acousto Ultrasonic Factor (AUF) has been defined for this purpose. The behavior of the AUF response to specimens of known quality is investigated statistically. It is found that the transformed/actual readings follow a Beta distribution and that specimens of different quality are readily distinguishable using the statistical analysis of the AUF response. Reasonable future steps for translating these findings into efficient quality evaluation methods have been suggested.</p / Master of Science

Thesis (PhD (Food Science))--University of Stellenbosch, 2007. / Thermal pasteurisation failures in the dairy industry have often been found to cause end-products of poor quality and short shelf-life. Therefore, alternative methods to eliminate microbial contaminants in raw milk are being studied. Ultrasonication is one such non-thermal technology that could offer the dairy industry an alternative to traditional pasteurisation. The main objective of this dissertation was to evaluate the use of high-power lowfrequency ultrasound (20 kHz, 750 W, 124 μm) applied in batch mode to eliminate a selection of spoilage and potentially pathogenic microbes, commonly associated with milk. These included Gram-positive and negative microbes, comprising of rods and cocci, an endospore-former, and a yeast (Escherichia coli, Bacillus cereus, Chryseobacterium meningosepticum, Lactobacillus acidophilus, Lactococcus lactis, Listeria monocytogenes, Micrococcus luteus, Pseudomonas fluorescens and Saccharomyces cerevisiae). Three strains of E. coli (1 x 106 cfu.ml-1) tested, viz. ATCC 11775, a wild strain from raw milk, and an O157:H7 strain from milk were sensitive to ultrasonication. Complete elimination of viable cells occurred within 10 min. Viable counts of P. fluorescens were reduced by 100% within 6 min of ultrasonication and L. monocytogenes was reduced by 99.0% within 10 min. Lactococcus lactis was reduced by 97.0% and M. luteus, B. cereus and C. meningosepticum by 88.0%, 87.0% and 85.0% respectively. Lactobacillus acidophilus showed the most resistance to ultrasound with only 78.0% of viable cells being eliminated. Under similar conditions, S. cerevisiae was reduced by 99.7%. Microbial cell morphology, size and Gram status did not necessarily influence the efficacy of ultrasonication. Sterile saline solution and UHT milk were used as the suspension media, and the reputed protective effect of milk fat was not observed under the parameters used in this study. A higher wave amplitude (100%; 124 μm) was found to be more efficient in eliminating microbes than a lower wave amplitude (50%; 62 μm). Pulsed-ultrasonication did not enhance the efficiency of ultrasonication indicating that standing waves were absent. Limited success was achieved by ultrasonication itself, and the long batch treatment time (10 min or more) was found to be unrealistic for industrial implementation. Hence the simultaneous application of ultrasound and heat (thermoultrasonication) was examined. Thermo-ultrasonication proved to be more effective than either an ultrasonic or heat treatment with all viable M. luteus cells being eliminated within 4 min (100% amplitude at 72°C). Similarly, to eliminate E. coli and Lb. acidophilus from milk, only 2 min and 4 min thermo-ultrasonication was required, respectively. Bacillus cereus endospores remained resistant and after a 10 min thermo-ultrasonic treatment only 78.04% were eliminated. During this investigation both extensive surface (SEM) and internal (TEM) cell damage caused by ultrasonication were observed in E. coli, Lb. acidophilus and S. cerevisiae. Hence ultrasonication physically/mechanically damages these microbial cells causing cell death/injury. Microbial proteins and DNA released from cells into the environment after an ultrasonic treatment was measured and an increase in released microbial proteins and DNA was found to be indicative of a decrease in the number of viable cells, providing that the initial cell concentration was high enough. It was, however, not possible to correlate the concentration of released microbial proteins and DNA with the exact number of viable cells eliminated, rendering it an ineffective quality indicator for the industry. Ultrasonication had no statistically significant influence on the protein, fat and lactose content of both raw and pasteurised milk. The somatic cell count of raw and pasteurised milk was found to decrease after ultrasonication. Unlike with heating, activity of alkaline phosphatase and lactoperoxidase were not reduced by ultrasonication. Hence neither enzyme can be used to indicate a successful ultrasonic treatment of milk. This study has demonstrated that ultrasonication offers a viable alternative to pasteurisation as it is effective in eliminating microbes, and does not alter native milk components. However, to attain a more effective killing, thermo-ultrasonication is recommended for the treatment of milk to be used for the production of different dairy products.

Wei, Fangyuan. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 182-211). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

O solo é base de praticamente todas as obras de Engenharia Civil e em algumas situações este não apresenta condições de suportar o carregamento imposto. Tal problema pode ser solucionado com técnicas de estabilização. A estabilização com cal é uma técnica clássica, porém não apresenta um método racional de dosagem e uma superfície de falha tridimensional conhecida. Entretanto este quadro vem alterando-se por meio de pesquisas que buscam utilizar o coeficiente porosidade/teor volumétrico de cal para dosar solo-cal. Assim, esta pesquisa tem como objetivo avaliar a influencia do coeficiente n/(Liv) na variação de resistência à tração na compressão diametral de misturas solo- cinza volante-cal para diferentes temperaturas e diferentes tempos de cura. Busca-se obter, também, a envoltória de ruptura tridimensional deste material. Para isso foram realizados ensaios de tração por compressão diametral em corpos de prova da mistura areia de Osório e cinza volante com 3, 5 e 7 % de cal (em peso), com peso especifico aparente seco de 14, 15 e 16 kN/m², curados a 20, 27, 35, 50, 65,80 e 90ºC por 1, 3 e 7 dias. Ensaios em Triaxial Verdadeiro e de ondas ultrassônicas foram executadas em amostras com 3 dias de cura a 35º, 3% de cal, peso específico seco de 14kN/m³ e nvariando de 0 até 180º. A relação porosidade/teor volumétrico de cal ajustado por um coeficiente [n/(Liv)0,3] mostrou-se adequada na previsão da resistência à tração para todas as temperaturas e tempos de cura estudados. O uso deste coeficiente permitiu a obtenção de curvas que permitem o cálculo da temperatura máxima que influência na resistência da mistura estudada para cada tempo de tempo. Este coeficiente também permitiu a obtenção de uma equação capaz de determinar a resistência máxima que pode ser obtida em cada tempo de cura independente da temperatura de cura. A envoltória de ruptura encontrada tem formato não circular, logo a resistência do material é dependente do caminho de tensões. A isotropia do material foi confirmada através da comparação entre caminhos de tensão iguais, porém executados em diferentes direções e através da comparação entre o Módulo Oedométrico há pequenas deformações (M0)e o Módulo de Cisalhamento há pequenas deformações (G0) das direções x, y e z da amostra. / Soil is the base of most civil engineering constructions, and when it cannot support the construction loads, such problem can be solved through the use of soil stabilization technique. Lime stabilization is a classical technique, but does not present a rational dosage method and a known three-dimensional failure envelope. This situation has been changed with researches using the porosity/lime ratio to dose soil-lime. Thereby this research aims to evaluate the influence of the quotient n/(Liv) in the assessment of splitting tensile at different temperatures and time of curing and find. It was also looked for the three dimensional rupture envelope of this material. For this research splitting tensile tests were carried out with lime contents varying from 3% to 7%, dry unit weight ranging from 14kN/m³ to 16kN/m³, time curing varying from 1 to 7 days and curing time varying from 20º to 90º. True Triaxial tests and ultrasonic waves tests were carried out with samples with 3% of lime content, 14kN/m³ of dry weight, 3 days of curing at 35º and nangle between nz and the consider stress path) in ranging from 0º to 180º. The porosity/lime ratio, defined as the ratio of the compacted mixture porosity and the lime volumetric content, adjusted by an exponent, proves to be an appropriate parameter to estimate the splitting tensile strength of the soil-fly ash-lime studied in all time and temperature studied. The use of this coefficient allowed obtaining curves that allow the calculation of the maximum temperature that influences the resistance of the studied mixture for each time period. This coefficient also allowed obtaining an equation capable of determining the maximum resistance that can be reached in each curing time independent of curing temperature. The failure envelope found has a non-circular shape, so the strength of the material is dependent on the stress path. The isotropy of the material was confirmed by comparing equal stress paths, but executed in different directions and by comparing the Oedometric Modulus in small strains (M0 ) and Shear Modulus in small strains (G0 ) of the x, y, and z directions the sample.