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Forward looking logics and automataLey, Clemens January 2011 (has links)
This thesis is concerned with extending properties of regular word languages to richer structures. We consider intricate properties like the relationship between one-way and two-way temporal logics, minimization of automata, and the ability to effectively characterize logics. We investigate whether these properties can be extended to tree languages or word languages over an infinite alphabet. It is known that linear temporal logic (LTL) is as expressive as first-order logic over finite words [Kam68, GPSS80]. LTL is a unidirectional logic, that can only navigate forwards in a word, hence it is quite surprising that it can capture all of first-order logic. In fact, one of the main ideas of the proof of [GPSS80] is to show that the expressiveness of LTL is not increased if modalities for navigating backwards are added. It is also known that an extension of bidirectional LTL to ordered trees, called Conditional XPath, is first-order complete [Mar04]. We investigate whether the unidirectional fragment of Conditional XPath is also first-order complete. We show that this is not the case. In fact we show that there is a strict hierarchy of expressiveness consisting of languages that are all weaker than first-order logic. Unidirectional Conditional XPath is contained in the lowest level of this hierarchy. In the second part of the thesis we consider data word languages. That is, word languages over an infinite alphabet. We extend the theorem of Myhill and Nerode to a class of automata for data word languages, called deterministic finite memory automata (DMA). We give a characterization of the languages that are accepted by DMA, and also provide an algorithm for minimizing DMA. Finally we extend theorems of Büchi, Schützenberger, McNaughton, and Papert to data word languages. A theorem of Büchi states that a language is regular iff it can be defined in monadic second-order logic. Schützenberger, McNaughton, and Papert have provided an effective characterization of first-order logic, that is, an algorithm for deciding whether a regular language can be defined in first-order logic. We provide a counterpart of Büchi's theorem for data languages. More precisely we define a new logic and we show that it has the same expressiveness as non-deterministic finite memory automata. We then turn to a smaller class of data languages, those that are recognized by algebraic objects called orbit finite data monoids. We define a second new logic and show that it can define precisely the languages accepted by orbit finite data monoids. We provide an effective characterization of a first-order variant of this second logic, as well as of restrictions of first-order logic, such as its two variable fragment and local variants.
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Design and Characterization of an Altitude Chamber for Chemical Rocket EnginesJacob M McCormick (7043039) 15 August 2019 (has links)
<p>This thesis focuses on the development of reduced pressure
testing capabilities at Zucrow Laboratories.
A two-stage ejector on loan from NASA Marshall is used in series with a
supersonic diffuser to allow for the testing of up to100 lb<sub>f</sub> rocket
engines at equivalent altitudes of up to 100,000 ft. The objective of this research is to
implement a one-dimensional (1-D) model which accurately predicts the
performance of the two-stage ejector in real time, informing the maximum thrust
and simulated altitude capabilities within the altitude chamber located in room
134A of ZL3 during experimental testing.</p>
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[en] EFFECT OF INTERFACE ROUGHNESS AND HEAT-TREATMENT OF THE SUPERCONDUCTING PROPERTIES OF NB/CO MULTILAYERS / [pt] RUGOSIDADE DA INTERFACE E EFEITO DE TRATAMENTO TÉRMICO NAS PROPRIEDADES SUPERCONDUTORAS DE MULTICAMADAS NB/COLIYING LIU 21 November 2012 (has links)
[pt] Neste trabalho foram preparadas multi-camadas supercondutor(SC)/
ferromagneto(FM) Nb/Co via pulverização catódica (Magnetron Sputtering).
O principal objetivo é estudar o efeito de diferentes espessuras da camada
ferromagnética (Co) nas propriedades supercondutoras do Nb. Era esperado
que, após tratamentos térmicos, as camadas de Co formassem um plano de
nanopartículas magnéticas ordenadas, cujo efeito deve ser muito diferente das
nanopartículas aleatoriamente orientadas e camadas magnéticas continuas. As
microestruturas foram investigadas por Difração de Raios-X em baixos ângulos
(LAXRD), Microscopia de Força Atômica (AFM) e Microscopia Eletrônica
de Transmissão (TEM). Propriedades magnéticas e de transporte tem sido
estudadas com o Sistema de Medição de Propriedade Físicas (PPMS), da
empresa Quantum Design. As medidas magnéticas e de transporte mostram
que, com o aumento da espessura das camadas de Co, a temperatura de
transição supercondutora (Tc) aumenta significativamente para as amostras
como preparadas. Foi relatado na literatura que quando a espessura das
camadas magnéticas da ordem de alguns nanômetros, a Tc aumenta e diminui
periodicamente com o aumento da espessura das camadas magnéticas. No
entanto, nesta pesquisa, a espessura das camadas magnéticas é de dezenas
de nanômetros, sendo muito maior do que este alcance e portanto, não pode
ser explicado baseando-se no mesmo modelo. Propusemos que a rugosidade da
interface entre as camadas de Co e Nb desempenha um papel importante para
este comportamento. Os resultados de AFM e XRD mostram que a rugosidade
máxima da interface é da ordem de 7 a 10 nm, o que é comparável à espessura
de camadas de Co (de 5 a 20 nm). Introduzimos um parâmetro R igual a d,
onde R é a rugosidade da interface e d é a espessura da camada magnética,
para discutir o efeito da interface sobre as propriedades supercondutoras da
nossa amostra. Quando delta maior que 1, a camada magnética pode ser considerada uma
forma não-continua e somente quando delta menor que 1, as camadas magnéticas continuas
podem ser formadas. Com base em observações de topografia de interfaces
na nano-escala , podemos compreender que primeiro a rugosidade aumenta a
área da interface, resultando em um efeito de proximidade mais forte, além
de aumentar o efeito do campo de dispersão na Tc. Este efeito depende não
somente da rugosidade, mas também da espessura da camada magnética.
Verificou-se que o parâmetro determina o efeito das camadas magnéticas.
As diferentes propriedades magnéticas abaixo da Tc para diferentes amostras
também pode ser explicada por este modelo. Após o tratamento térmico, a Tc
das amostras diminuiu e as propriedades magnéticas também se tornam piores
do que as amostras como preparadas. Os resultados de TEM mostram que as
camadas de Co estam interconectadas e depois do recozimento não há indícios
de interdifusão entre as camadas Nb e Co. Mais medidas são necessárias
para verificar se as camadas magnéticas podem induzir vórtices espontâneos,
assim como para explicar a diferença entre as amostras com nanopartículas
magnéticas ordenadas comparadas com aquelas orientadas aleatoriamente. / [en] In this work we prepared Superconductor(SC)/ferromagnet(FM) Nb/Co
multi-layers with magnetron-sputtering. The main purpose of this work is to
study the effect of different shape of ferromagnetic layers on the superconducting
properties of Nb. We expected that after annealing the Co layers can form
in-plane ordered magnetic nanoparticles and the effect of ordered magnetic
nanoparticles should be very different from randomly oriented nanoparticles
and continues magnetic layers. The microstructures have been investigated
by means of Low Angle X-ray Diffraction (LAXRD), Atomic Force Microscopy
(AFM) and Transmission Electron Microscopy (TEM). Magnetic and
transport properties have been studied with Physical Property Measurement
System (PPMS) from Quantum Design. The magnetic and transport measurements
show that with increase of the thickness of Co layers the superconducting
transition temperature (Tc) signifficantly increases for the as-prepared samples.
It was reported in the literature that when the thickness of the magnetic layers
is in the range of several nanometers, Tc increases and decreases periodically
with the increase of the thickness of the magnetic layers. In our samples, however,
the thickness of the magnetic layers (several tens nanometers) is much
larger than that range and therefore, cannot be explained within the same
model. We proposed that the roughness of the interface between Co and Nb
layers plays an important role for this behavior. The AFM and LAXRD results
show that the maxim roughness of the interface is in the range of 7 until 10 nm,
which is comparable to the thickness of Co layers (5 until 20 nm). We introduced
one parameter R equal d, where R is the roughness of the interface and d is
the thickness of the magnetic layer, to discuss the effect of the interface on
the superconducting properties of our sample. When delta more 1, the magnetic layer
may be in a non-continues form and only when delta less1 continues magnetic layers
can be formed. Based upon nano-scale observations of interfaces topography
we can understand that the roughness first increases the area of the interface,
which gives stronger proximity effect and, second, enhances the effect of the
stray eld on Tc. This effect depends not only the roughness but also the thickness
of the magnetic layer. It was found out that the parameter determines
the effect of the magnetic layers. The different magnetic properties below Tc
for different samples can also be explained by this model. After annealing, Tc
of the samples decreased and magnetic properties also became worse than the
as-prepared samples. The TEM results show that the Co layers is interconnected
and after annealing there is no indication of interdiffusion between Nb and
Co layers. More measurements are needed to see if the magnetic layers can
induce spontaneous vortices and what the difference is between samples with
ordered and randomly oriented magnetic nano-particles.
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Méthodes robustes en traitement d'image pour la détection et la caractérisation d'objets compacts : application à la biologie / Robust image analysis methods for the detection and the characterization of compact objects : application to biologyMarin, Ambroise 05 July 2019 (has links)
Dans le domaine de la microbiologie, de nombreuses expériences se basent sur une fine observation des micro-organismes. De par leur intérêt dans le développement de procédés agroalimentaires modernes, il est important d’étudier leur développement et leur taux de survie dans des conditions environnementales spécifiques telles que des stress osmotiques ou thermiques. L’imagerie microscopique est un des outils les plus utilisés pour observer les micro-organismes. L’interprétation manuelle des images acquises pose des problèmes de subjectivité, de coût et reproductibilité. Cette thèse propose le développement d’outils d’analyse d’image standardisés permettant l’interprétation des images à deux échelles :- A l’échelle de la lame d’observations : l’utilisation de lames de comptage spécifiques (Malassez) permet, à partir du comptage des cellules présente dans la zone d’intérêt de la lame, de déduire la concentration cellulaire d’une solution de Saccharomyces cerevisiae soumises à un stress osmotique. Les outils développés permettent l’identification et la caractérisation de cette zone d’intérêt (grille) puis le comptage précis des cellules.- A l’échelle de la cellule : une souche mutante de Saccharomyces cerevisiae permet d’observer en fluorescence la protéine Pab1p-GFP impliquée dans la formation d’agrégats ribo-nucléoprotéiques intracellulaires consécutifs à un stress thermique. Les outils développés permettent d’obtenir une vue statistique du développement de ces agrégats grâce à l’automatisation de l’estimation de leur nombre pour un très grand nombre de cellules. / In the field of microbiology, many experiments are based on a fine observation of microorganisms. Because of their interest in the development of modern agri-food processes, it is important to study their development and survival rate under specific environmental conditions such as osmotic or thermal stress. Microscopic imaging is one of the most used tools for observing microorganisms. The manual interpretation of acquired images raises problems of subjectivity, cost and reproducibility. This thesis proposes the development of standardized image analysis tools allowing the interpretation of images at two scales:- At the scale of the observation slide: the use of specific counting slides (Malassez) allows, from the counting of the cells present in the zone of interest of the slide, to deduce the cell concentration of a solution of Saccharomyces cerevisiae subjected to osmotic stress. The tools developed allow for the identification and characterization of this area of interest (grid) and precise counting of the cells.- At the cell scale: a mutant strain of Saccharomyces cerevisiae allows for the observation in fluorescence the Pab1p-GFP protein involved in the formation of intracellular ribo-nucleoprotein aggregates consecutive to thermal stress. The tools developed allows for obtaining a statistical view of the development of these aggregates by automating the estimation of their number for a very large number of cells.
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Modifying the three-dimensional network of polyamide 6,10 for designing a novel drug delivery systemKolawole, Oluwatoyin Ayotomilola 29 September 2008 (has links)
ABSTRACT WOULD NOT COPY
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Impact du procédé de fabrication des stators slinky sur les propriétés des matériaux / Impact of manufacturing process of slinky stators on the properties of materialEl youssef, Mohamad 21 December 2017 (has links)
La machine synchrone à griffes est un dispositif très utilisé comme alternateur dans l’automobile. La fabrication de cette machine, produite en masse, met en œuvre des procédés impactant les caractéristiques des matériaux ferromagnétiques et donc, in fine , les performances de l’alternateur. Ce travail de thèse est donc consacré à étudier l’impact du processus de fabrication d’un stator Slinky (basé sur un enroulement d’une bande de tôle plutôt qu’un empilement) sur les propriétés magnétiques. Pour ce faire, une première partie du travail consiste à quantifier l’impact de chaque procédé mis en œuvre. Le but est de séparer les procédés les plus fortement impactant. Une campagne de caractérisation magnétique, sur des échantillons prélevés avant et après chaque procédé, a été réalisée. Les résultats montrent que le procédé d’enroulement est l’étape la plus destructive à cause des déformations et des contraintes engendrées dans le plan de la tôle à la fois en traction et en compression. L’optimisation de ce procédé nécessite donc d’établir le lien entre les propriétés mécaniques et magnétiques. Nous proposons une nouvelle méthode de caractérisation magnéto-mécanique. Elle permet de réaliser une caractérisation magnétique sous chargement uni axial en traction et en compression. Enfin, nous présentons des résultats montrant l’évolution du comportement magnétique, d’un matériau FeSi NO, en fonction de la déformation et de la contrainte appliquée. / The synchronous claw pole machine represents a widely used device, as an alternator, in the automobile industry. The production of this machine implements a line of several processes which impact the characteristics of ferromagnetic materials and, ultimately, the performance of the alternator. Therefore, this work is devoted to studying the impact of the manufacturing processes of a Slinky stator (based on a rolled sheet metal strip rather than stacked sheets) on the magnetic properties. To reach our goal, a first task consists in quantifying the impact of each manufacturing process. The aim is to separate the most detrimental processes. Thus, a magnetic measurement campaign was carried out on samples withdrawn before and after each process.The results show that the rolling step represents the most detrimental process due to the generated stresses and strains in the plane of the sheet in both modes (tension and compression). Therefore, the optimization of this process requires setting up the link between the mechanical and magnetic properties. Hence, we propose a new method of magneto-mechanical characterization. It enables to carry out magnetic measurements under uniaxial loading (tension and compression). Finally, we present results showing the evolution of the magnetic behavior of a FeSi NO material depending on the applied stress and strain.
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Caracterização eletrostática de tapetes e carpetes / not availableFaesarella, Annete Silva 29 March 2001 (has links)
Quando uma pessoa fricciona os sapatos num tapete, seu corpo pode carregar-se com um potencial de alguns milhares de volts em relação ao referencial de terra. Se esta pessoa tocar um objeto aterrado, uma faísca pode salta entre o objeto e a ponta do seu dedo. O corpo desta pessoa age como um capacitor, e um fluxo rápido de eletricidade estática armazenada, resultado das cargas estáticas armazenadas no copo, flui deste para um objeto de potencial menor. Essas descargas podem provocar desde pequenos danos, como desconforto físico, até incêndios em grandes construções. Na tentativa de minimizar ou eliminar esses problemas, tapetes e carpetes antiestáticos são utilizados. Muitos métodos têm sido propostos para caracterizar esses produtos de acordo com suas características eletrostáticas. Dentre eles, o recomendado pela norma francesa NF G35-025 [Essais des Revêtements de Sol Textiles-Propension à l\'accumulation de Charges Életrostatiques, Méthode d\'essai et spécification, Décembre 1983], prescreve que alguém usando sapatos especiais deve caminhar em uma amostra de tapete por longo período e, então, o potencial eletrostático adquirido por ele é medido através de um eletrômetro. Por este método são reproduzidas as condições reais, mas, ele é muito caro e trabalhoso, pois requer uma sala climatizada. Na tentativa de descobrir métodos alternativos, encontram-se na literatura vários estudos e métodos. Taylor [An Instrument for Measuring Static Dissipation from Materials, Journal of Electrostatics, (1987) 53-64, Elsevier Science Publishers B.V., Amsterdam-Printed in the Netherlands] desenvolveu um medidor de decaimento de carga para medir tempo de decaimento em polímeros antiestáticos. Nesse método, ele determinou uma boa correlação entre a resistência superficial e o tempo de meia-vida do material. Usando a mesma ideia, foi possível desenvolver o método apresentado nesta tese, aplicado a amostras de tapete e carpetes. Neste método, a caracterização eletrostática de tapetes ou carpetes é realizada também através da medida do tempo de decaimento do potencial eletrostático. Porém, sua ideia principal é que todas as medidas são realizadas dentro de uma câmara especial isenta de umidade, pois este pode influenciar o carregamento das amostras. Dentro desta câmara, as amostras de tapete ou carpete são inicialmente carregadas através de descarga corona, após cessar o carregamento, é medido o seu tempo de decaimento. Um programa computacional especialmente desenvolvido para este fim permite o controle da medição e do processo de carregamento. / When a person rubs his shoes in a rug, his body may be charged with a potential of some thousands of volts in relation to the earth reference. If this person touches a grounded object, a spark can travel between the object and the tip of his finger. The person\'s body acts like a capacitor, and a fast flow of stored static electricity, which is a result of the static loads stored in the body, flows from the body to an object in a smaller potential. Those discharges can cause from small damages, as physical discomfort, to fires in big constructions. ln the attempt to minimize or to eliminate these problems, antiestatic rugs and carpets are used. Many methods have been proposed 10 characterize those products in agreement with the electrostatic characteristics . Among them the recommended methods by the French standard NF G35-025 [Essais des Revêtements de Sol Textiles-Propension à I\'accumulation de Charges Életrostatiques, Méthode d\'essai et spécification, Décembre 1983], prescribe that somebody using special shoes should walk in a rug sample for a long period, and then the electrostatic potential acquired by him is measured using an electrometer. ln this method the real conditions are reproduced, but, it is very expensive and difficult, because it requires an aclimatized room. There are in the literature several studies attempting to devise alternative methods. Taylor [An Instrument goes Measuring Static Dissipation from Materiais, Journal of Electrostatics, (1987) 53-64, Elsevier Science Publishers B. V, Amsterdam-Printed in the Netherlands] developed a meter of charge decline to measure time of decline in antistatic polymers. ln his method, Taylor determined a good correlation between the superficial resistance and the time of stocking-life of the material. Using the same idea, it was possible to develop the method that is presented in this thesis, applied to samples of rugs and carpets. ln this method the electrostatic characterization of rugs or carpets is also accomplished through the measurement of the time of decline of the electrostatic potential. However its main idea is that all the measures are accomplished inside a special camera without humidity, since it can influence the charging of the samples. lnside this camera, the rugs or carpet samples are initially charged using corona discharge, after interrupting the charging, time of decline is measured. A computer program was especially developed for this reason, it allows the control of the measurement and of the charging process.
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Desenvolvimento de método para caracterização de embalados de rejeitos radioativos / Development of a method for the radioisotopic characterization of waste packagesSouza, Daiane Cristini Barbosa de 16 September 2013 (has links)
Atualmente, a caracterização dos resíduos radioativos gerados na operação do reator nuclear de pesquisas IEA-R1 está em curso. O reator IEA-R1 é um reator do tipo piscina aberta, moderado e refrigerado por água leve, utilizando dois leitos de resinas de troca iônica e de carvão ativado para purificação de água de refrigeração. Estes meios filtrantes são substituídos quando já não são capazes de manter a qualidade da água dentro dos limites exigidos e são tratados como rejeitos radioativos. Contendo produtos de fissão, ativação e actinídeos que escapam do núcleo do reator para a água da piscina, apresentam altas taxas de dose devido à quantidade de emissores gama de meias-vidas curtas e intermediárias, emissores alfa, elementos transurânicos de meia-vida longa bem como emissores beta puros. A caracterização destes rejeitos, consequentemente, requer métodos de análise radioquímica que incluem a amostragem e o processamento das amostras, resultando em doses elevadas para os trabalhadores. Nesse contexto, o objetivo deste trabalho consistiu em correlacionar os resultados das análises radioquímicas de amostras de rejeitos, com os resultados das medições radiométricas, utilizando a modelagem das taxas de dose em diferentes distâncias da superfície dos embalados. As taxas de dose medidas foram comparadas com os resultados de cálculos . Massa, volume e geometria das fases sólidas e líquidas de cada um dos tambores também foram determinadas, uma vez que o teor de água varia amplamente entre diferentes tambores, e são essenciais para estimar as atividades totais em cada tambor. / The characterization of the radioactive wastes generated in the operation of the nuclear research reactor IEA-R1 is currently ongoing. The IEA-R1 is an open pool type reactor, moderated and cooled by light water that uses two beds of ion-exchange resins and activated charcoal to remove impurities from the cooling water. These filter media are replaced when they are no longer able to maintain water quality within the required limits and are treated as radioactive waste. They contain the actinides and the fission and activation products that leaked into the reactor pool water. They give off high dose rates due to the amount of gamma-emitters present and are a long-term radiation safety concern because of their content of long-lived alpha- and beta-emitters. The characterization of these wastes requires radiochemical analysis methods, which include the sampling and processing of samples, resulting in high exposure to the workers. The objective of this study was to correlate the results of activity concentrations obtained in previous radiochemical analyses with the results of measurements of dose rates at various distances from the package surfaces, aiming at reducing the exposure of personnel by avoiding more sampling and sample analysis operations. Mass, volume and geometry of solid and liquid phases of each drum, which vary widely among different drums, were also estimated and use to determine total activity. The measured and calculated dose rates were compared to confirm the activity estimates.
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Caracterização mecânica de um robô manipulador paralelo de 3 graus de liberdade. / Mechanical characterization of a parallel manipulator robot with 3 degrees of freedom.Rinaldi, Decio de Moura 14 May 2018 (has links)
Esta dissertação aborda a caracterização mecânica de um robô manipulador paralelo de 3 graus de liberdade. A topologia do manipulador corresponde a um mecanismo de estrutura cinemática paralela, cujo efetuador é capaz de realizar 3 deslocamentos lineares no espaço tridimensional. A tecnologia associada ao controle de robôs de estrutura cinemática serial encontra-se bastante madura. No entanto, o mesmo não se dá nos robôs paralelos. Para que se avance no domínio do controle de trajetória destes robôs é necessária a sua caracterização mecânica, a qual fornecerá os subsídios para identificação paramétrica, calibração de modelos, ajuste de ganhos dos controladores, etc. Especificamente, a caracterização mecânica neste trabalho teve por objetivo o levantamento experimental dos erros de posicionamento do efetuador com relação a exatidão e repetibilidade, sua rigidez sob a ação de cargas externas, bem como das frequências naturais do sistema. Os ensaios realizados foram executados no robô Laila, que é um protótipo físico de um robô manipulador, desenvolvido pelo Departamento de Engenharia Mecatrônica e Sistemas Mecânicos da Escola Politécnica da Universidade de São Paulo. A dissertação apresenta como resultados os mapeamentos dos erros de posicionamento do efetuador, a rigidez sob a ação de cargas externas, bem como suas frequências naturais, ao longo do espaço de medição. A seguir, apresenta-se uma discussão da consistência dos valores obtidos para estas propriedades. Por fim, é feita uma análise sobre a influência das folgas mecânicas sobre os índices de desempenho do robô. / This dissertation deals with the mechanical characterization of a parallel manipulator robot of 3 degrees of freedom. The topology of the manipulator corresponds to a mechanism of parallel kinematic structure, whose effector is capable of performing 3 linear displacements in the three-dimensional space. The technology associated with the control of robots of serial kinematic structure is quite mature. However, the same is not true of parallel robots. In order to advance in the field of control of trajectory of these robots it is necessary to characterize them mechanically, which will provide the subsidies for parametric identification, calibration of models, adjustment of gains of the controllers, etc. Specifically, the mechanical characterization in this work had as objective the experimental study of the positioning errors of the effector in relation to the accuracy and repeatability, its rigidity under the action of external loads, as well as the natural frequencies of the system. The tests were performed in the Laila robot, which is a physical prototype of a manipulator robot, developed by the Department of Mechatronics Engineering and Mechanical Systems of the Polytechnic School of the University of São Paulo. The dissertation presents as results the mappings of the positioning errors of the effector, the rigidity under the action of external loads, as well as their natural frequencies, along the measurement space. The following is a discussion of the consistency of the values obtained for these properties. Finally, an analysis is made on the influence of the mechanical gaps on the performance indexes of the robot.
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Estudos termoanalíticos dos edulcorantes acessulfame-K, aspartame, ciclamato, esteviosídeo e sacarina / Thermoanalytical studies of the sweeteners acesulfame-K, aspartame, ciclamate, stevioside and sacharineCarvalho, Lucinéia Cristina de 30 July 2007 (has links)
Neste trabalho, estudou-se a decomposição térmica dos edulcorantes não calóricos acessulfame-K, aspartame, ciclamato de sódio, esteviosídeo, sacarina e sacarina sódica de crescente uso na indústria alimentícia. Para tanto, essas amostras foram submetidas à análise por TG, DTG DTA e DSC, após caracterização por análise elementar e por IV. Após recristalização dos compostos comerciais ciclamato de sódio e sacarina sódica, observou-se nas curvas TG a presença de águas de hidratação no aspartame e na sacarina sódica. Nesta última, a primeira água é muito volátil e pode ser eliminada na secagem. O esteviosídeo apresentou umidade. Os intermediários e os resíduos dos mesmos foram caracterizados por IV e quando necessário por difração de raios X. De maneira geral os compostos apresentaram decomposição com formação de resíduo carbonizado e geração de sulfato de potássio, no caso do acessulfame-K e sulfato de sódio na sacarina e ciclamato de sódio. Estudos de cinética de decomposição em fase sólida foram realizados para o aspartame e sacarina, pois estes não apresentavam sobreposição de eventos. Os estudos cinéticos para decomposição térmica usando o método de Flynn-Wall-Ozawa só puderam ser realizados para o aspartame resultando em log A = 23,2 +-0,1 min-1 e Ea = 206,6 +- 0,3 KJ mol-1. Os demais compostos apresentaram decomposição por eventos simultâneos, que dificultam os cálculos cinéticos. A sacarina H apresentou volatilização após fusão, com Ea = 154,9 +- 0,7 KJ mol-1 e log A = 15,2 +- 0,1 min-1. / In this work the thermal decomposition of the non-caloric sweeteners acesulfame-K, aspartame, sodium ciclamate, stevioside, saccharine and sodium saccharine was performed. Initially, the compounds were characterized usually elemental analysis and IR spectroscopy some were recrystallised from commercial samples, resulting in purified compounds. After characterization the sweetener were analysed by TG/DTG, DTA and DSC. The recrystallised compounds presented hydration water in aspartame and sodium saccharine. In the last the first water can be lost during drying, since it seems to be weakely bounded. Stevioside showed humidity water. In a general way the sweeteners decomposes by a carbonaceous residue, and formed potassium sulfate as final residue in the acesulfame-K case as well as sodium sulfate in sodium saccharine and sodium ciclamate. Due to the overlapping of consecutive decomposition steps. The use o the Flynn-Wall-Ozawa method for kinetic calculations only could be performed for the decomposition of aspartame, resulting in log A = 23,2 +-0,1 min-1 and Ea = 206,6 +-0,3 KJ mol-1. The volatilization of saccharine H, after fusion, resulted in Ea = 154,9 +-0,7 KJ mol-1 and log A = 15,2 +-0,1 min-1.
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