• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 404
  • 129
  • 99
  • 44
  • 39
  • 28
  • 11
  • 10
  • 7
  • 6
  • 4
  • 4
  • 3
  • 3
  • 2
  • Tagged with
  • 966
  • 200
  • 127
  • 118
  • 90
  • 81
  • 77
  • 72
  • 69
  • 69
  • 63
  • 62
  • 61
  • 53
  • 51
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
821

Analyse spectrale des signaux chaotiques / Spectral analysis of chaotic signals

Feltekh, Kais 12 September 2014 (has links)
Au cours des deux dernières décennies, les signaux chaotiques ont été de plusen plus pris en compte dans les télécommunications, traitement du signal ou transmissionssécurisées. De nombreux articles ont été publiés qui étudient la densitéspectrale de puissance (DSP) des signaux générés par des transformations spécifiques.La concentration sur la DSP est due à l’importance de la fréquence dans lestélécommunications et la transmission sécurisée. Grâce au grand nombre de systèmessans fil, la disponibilité des fréquences de transmission et de réception est de plus enplus rare pour les communications sans fil. Aussi, les médias guidés ont des limitationsliées à la bande passante du signal. Dans cette thèse, nous étudions certainespropriétés associées à la bifurcation collision de frontière pour une transformationunidimensionnelle linéaire par morceaux avec trois pentes et deux paramètres. Nouscalculons les expressions analytiques de l’autocorrélation et de la densité spectralede puissance des signaux chaotiques générés par les transformations linéaires parmorceaux. Nous montrons l’existence d’une forte relation entre les différents typesde densité spectrale de puissance (passe-bas, passe-haut ou coupe-bande) et les paramètresde bifurcation. Nous notons également en évidence une relation entre le typede spectre et l’ordre des cycles attractifs. Le type du spectre dépend de l’existencedes orbites périodiques au-delà de la bifurcation de collision de frontière qui a donnénaissance au chaos. Nous utilisons ensuite les transformations chaotiques pour étudierla fonction d’ambiguïté. Nous combinons quelques transformations chaotiquesbien déterminées pour obtenir un spectre large bande avec une bonne fonction d’ambiguïtéqui peut être utilisée en système radar / During the two last decades, chaotic signals have been increasingly consideredin telecommunications, signal processing or secure transmissions. Many papers haveappeared which study the power spectral density (PSD) of signals issued from somespecific maps. This interest in the PSD is due to the importance of frequency in thetelecommunications and transmission security. With the large number of wirelesssystems, the availability of frequencies for transmission and reception is increasinglyuncommon for wireless communications. Also, guided media have limitations relatedto the bandwidth of a signal. In this thesis, we investigate some properties associatedto the border-collision bifurcations in a one-dimensional piecewise-linear map withthree slopes and two parameters. We derive analytical expressions for the autocorrelationsequence, power spectral density of chaotic signals generated by our piecewiselinearmap. We prove the existence of strong relation between different types of thepower spectral density (low-pass, high-pass or band-stop) and the parameters. Wealso find a relation between the type of spectrum and the order of attractive cycleswhich are located after the border collision bifurcation between chaos and cycles.We use the chaotic transformations to study the ambiguity function. We combinesome chaotic transformations well determined to obtain a broadband spectrum witha good ambiguity function that can be used in radar systems
822

Cláusula de não concorrência no contrato de emprego: efeitos do princípio da proporcionalidade

Oliveira Neto, Celio Pereira 14 June 2013 (has links)
Made available in DSpace on 2016-04-26T20:21:41Z (GMT). No. of bitstreams: 1 celio Pereira Oliveira Neto.pdf: 1507882 bytes, checksum: 7103e8b0600844203d81f93da63c2f69 (MD5) Previous issue date: 2013-06-14 / Although there isn‟t a specific rule in the native law, the application of the non concurrence clause profits from the constitutional protection, which is based on the free initiative, private property, free concurrence, property law, consumer defense and general freedom law. Due to constitutional propagation, it enjoys equally of protection in the general clauses of the objective good faith and social function, besides the lawfulness presumption of the contract. On the other hand, there are some directives that can‟t be disregarded when having to limit the freedom right of the work. Indeed, the economical order must be based on the importance of the human work, as well as the reduction of the social inequalities and in the search of the perfect job. Moreover, the private property is established on the basis of the free exercise of any work, occupation or profession, that is to say, it must be observed the social right of the worker in choosing the developed activity, this means that any act that disrespect the importance of the work can be understood as unconstitutional. There is a clear confront between the non concurrence clause and the freedom work both under the constitutional protection in the articles 5° and 170 of the CF. The solution of this conflict is coped with the principles of proportionality, which it justifies and limits the application of the non concurrence clause. However, to reach such point, it‟s necessary the constitutional passage about the traditional methods of constitutional interpretation getting to the pos-positivist moment, taking care of the constitutional‟s principles of interpretation reading as a leading of the whole arrangement, differing from the rules relating them with the principle of proportionality use and its sub-principles of adequacy, necessity and proportionality in the strict way / Although there isn‟t a specific rule in the native law, the application of the non concurrence clause profits from the constitutional protection, which is based on the free initiative, private property, free concurrence, property law, consumer defense and general freedom law. Due to constitutional propagation, it enjoys equally of protection in the general clauses of the objective good faith and social function, besides the lawfulness presumption of the contract. On the other hand, there are some directives that can‟t be disregarded when having to limit the freedom right of the work. Indeed, the economical order must be based on the importance of the human work, as well as the reduction of the social inequalities and in the search of the perfect job. Moreover, the private property is established on the basis of the free exercise of any work, occupation or profession, that is to say, it must be observed the social right of the worker in choosing the developed activity, this means that any act that disrespect the importance of the work can be understood as unconstitutional. There is a clear confront between the non concurrence clause and the freedom work both under the constitutional protection in the articles 5° and 170 of the CF. The solution of this conflict is coped with the principles of proportionality, which it justifies and limits the application of the non concurrence clause. However, to reach such point, it‟s necessary the constitutional passage about the traditional methods of constitutional interpretation getting to the pos-positivist moment, taking care of the constitutional‟s principles of interpretation reading as a leading of the whole arrangement, differing from the rules relating them with the principle of proportionality use and its sub-principles of adequacy, necessity and proportionality in the strict way / Embora inexista regra específica no direito pátrio, a aplicação da cláusula de não concorrência goza de amparo constitucional, fundado na livre iniciativa, propriedade privada, livre concorrência, direito de propriedade, defesa do consumidor e direito geral de liberdade. Por irradiação constitucional, usufrui igualmente de amparo nas cláusulas gerais da boa-fé objetiva e função social do contrato, além da presunção de licitude do contrato. Por outro lado, há diretrizes que não podem ser desconsideradas quando se trata de limitar o direito de liberdade ao trabalho. Com efeito, a ordem econômica deve ser fundada na valorização do trabalho humano, bem como na redução das desigualdades sociais, e na busca do pleno emprego. Ademais, a propriedade privada é estabelecida com base no livre exercício de qualquer trabalho, ofício ou profissão ou seja, deve ser observado o direito social do trabalhador de escolher a atividade desenvolvida, o que significa que qualquer ato que desrespeite a valorização do trabalho poderá ser entendida como inconstitucional. Há nítido confronto, pois, entre a cláusula de não concorrência e a liberdade ao trabalho ambas com amparo constitucional nos arts. 5º e 170 da CF. A resolução desse conflito é enfrentada à luz do princípio da proporcionalidade, que justifica e limita a aplicação da cláusula de não concorrência. Porém, para se chegar a tal ponto, antes se faz necessária passagem constitucional, acerca dos tradicionais métodos de interpretação constitucional chegando ao momento pós-positivista, cuidando-se da leitura dos princípios de interpretação constitucional como vetores de todo o ordenamento, diferenciando-os das regras, e relacionando-os com o uso do princípio da proporcionalidade e seus subprincípios da adequação, necessidade e proporcionalidade em sentido estrito. Daí se observa que a Constituição Federal preserva ambos os bens, e a interpretação constitucional deve ser levada a efeito de modo a harmonizar o conflito, de sorte que um direito ceda ao outro no caso concreto, sem que isso represente a completa exclusão do direito preterido, conservando-se a unidade do sistema e promovendo-se a concordância prática através da ponderação de bens. O princípio da proporcionalidade passa a ser conceituado e aferido em todas as suas nuances, demonstrando-se os prós e contras de seu uso como critério para resolução de conflitos na sociedade contemporânea. Passa-se à análise do direito contratual contemporâneo, em que a autonomia da vontade é mitigada frente à defesa dos direitos sociais, e a responsabilidade pós-contratual é inserida com fulcro nas cláusulas gerais. Com o uso de todos os fundamentos apontados, torna-se ao debate original, justificando e limitando a cláusula de não concorrência, apresentando as possibilidades de uso da cláusula de não concorrência pós pactum finitum em uma relação de desigualdade como é o caso da relação de emprego, valendo-se do princípio da proporcionalidade e seus subprincípios, indicando-se as posições da doutrina e jurisprudência, sem olvidar do direito estrangeiro / Embora inexista regra específica no direito pátrio, a aplicação da cláusula de não concorrência goza de amparo constitucional, fundado na livre iniciativa, propriedade privada, livre concorrência, direito de propriedade, defesa do consumidor e direito geral de liberdade. Por irradiação constitucional, usufrui igualmente de amparo nas cláusulas gerais da boa-fé objetiva e função social do contrato, além da presunção de licitude do contrato. Por outro lado, há diretrizes que não podem ser desconsideradas quando se trata de limitar o direito de liberdade ao trabalho. Com efeito, a ordem econômica deve ser fundada na valorização do trabalho humano, bem como na redução das desigualdades sociais, e na busca do pleno emprego. Ademais, a propriedade privada é estabelecida com base no livre exercício de qualquer trabalho, ofício ou profissão ou seja, deve ser observado o direito social do trabalhador de escolher a atividade desenvolvida, o que significa que qualquer ato que desrespeite a valorização do trabalho poderá ser entendida como inconstitucional. Há nítido confronto, pois, entre a cláusula de não concorrência e a liberdade ao trabalho ambas com amparo constitucional nos arts. 5º e 170 da CF. A resolução desse conflito é enfrentada à luz do princípio da proporcionalidade, que justifica e limita a aplicação da cláusula de não concorrência. Porém, para se chegar a tal ponto, antes se faz necessária passagem constitucional, acerca dos tradicionais métodos de interpretação constitucional chegando ao momento pós-positivista, cuidando-se da leitura dos princípios de interpretação constitucional como vetores de todo o ordenamento, diferenciando-os das regras, e relacionando-os com o uso do princípio da proporcionalidade e seus subprincípios da adequação, necessidade e proporcionalidade em sentido estrito. Daí se observa que a Constituição Federal preserva ambos os bens, e a interpretação constitucional deve ser levada a efeito de modo a harmonizar o conflito, de sorte que um direito ceda ao outro no caso concreto, sem que isso represente a completa exclusão do direito preterido, conservando-se a unidade do sistema e promovendo-se a concordância prática através da ponderação de bens. O princípio da proporcionalidade passa a ser conceituado e aferido em todas as suas nuances, demonstrando-se os prós e contras de seu uso como critério para resolução de conflitos na sociedade contemporânea. Passa-se à análise do direito contratual contemporâneo, em que a autonomia da vontade é mitigada frente à defesa dos direitos sociais, e a responsabilidade pós-contratual é inserida com fulcro nas cláusulas gerais. Com o uso de todos os fundamentos apontados, torna-se ao debate original, justificando e limitando a cláusula de não concorrência, apresentando as possibilidades de uso da cláusula de não concorrência pós pactum finitum em uma relação de desigualdade como é o caso da relação de emprego, valendo-se do princípio da proporcionalidade e seus subprincípios, indicando-se as posições da doutrina e jurisprudência, sem olvidar do direito estrangeiro
823

Reconstruction de la Dynamique Précoce d'un Orogène : Mise en évidence de la Transition Rifting-Collision dans le système est-pyrénéen (France) par la Géo-thermochronologie / Reconstruction of early orogen dynamics : geo-thermochronological evidence of the rift-to-collision transition in the eastern Pyrénées (France)

Ternois, Sébastien 05 July 2019 (has links)
Les orogènes collisionnels sont classiquement décrits comme le résultat de l'accrétion continentale de marges proximales. Cette accrétion conduit à la surrection des reliefs et à l'export important de produits d'érosion dans les bassins d'avant-pays qui les jalonnent. Dans ce schéma géodynamique sont alors uniquement considérés les domaines pré-orogéniques les moins déformés. Pourtant, un nombre croissant d'évidences géologiques de terrain indiquent la conservation voire la réutilisation de structures héritées de la phase extensive précédant la convergence et la collision au coeur des orogènes. À partir de l'étude géo-thermochronométrique de la bordure orientale du domaine hyper-étiré nord-pyrénéen (massif de l'Agly, Zone Nord Pyrénéenne) et de son avant-pays précoce (synclinal de Rennes-les-Bains, Bassin Aquitain), cette thèse a pour objectifs de décrire l'évolution d'une marge distale au cours des premiers stades de convergence, de quantifier les processus source-réceptacle associés et d'apporter des contraintes temporelles et paléogéographiques quant à la création des tout premiers reliefs pyrénéens issus de son inversion. Grâce à l'utilisation du multi-thermochronomètre (U-Th)/He sur zircon et apatite, deux épisodes de refroidissement sont mis en évidence dans le prisme nord-pyrénéen (Campano-Maastrichtien et Eocène), chacun d'eux synchrone d'une phase de subsidence dans le bassin d'avant-pays. J'ai ainsi pu proposer un modèle équilibré d'évolution d'une marge distale hyper-amincie par inversion de structures héritées, chevauchements de socle et sous-placage continental se matérialisant par une signature thermochronologique claire de refroidissement sans érosion au début de la convergence. L'absence d'enregistrement de refroidissement au Paléocène par l'arrêt prématuré de l'inversion précoce dans le prisme nord-pyrénéen indique l'absence significative d'érosion et la position bordière de ce prisme par rapport à un édifice déjà construit plus à l'est à cette époque. Pour caractériser cet édifice aujourd'hui disparu du fait de l'ouverture du Golfe du Lion, j'ai utilisé une approche détritique de double datation in situ (U-Th)/He - U/Pb sur zircon et mis en évidence une histoire de dénudation rapide pendant le Campano-Maastrichtien, caractéristique de la création d'une topographie précoce. Ce travail montre pour la première fois clairement la migration progressive de la déformation d'est en ouest par l'inversion de structures héritées au début de la convergence pyrénéenne, ce qui suggère l'existence d'un domaine ouvert à l'est à la fin de l'épisode extensif précédant la convergence. Cette étude met en avant le rôle de l'architecture des systèmes hyper-amincis dans la formation des orogènes collisionnels et confirme les liens étroits existant entre un orogène et ses bassins d'avant-pays. / Collisional orogens are classically described as the result of continental accretion of proximal margins. This accretion leads to the creation of relief and to the important export of erosion products in the directly adjacent foreland basins. In this geodynamic scheme, only the least deformed pre-orogenic domains are considered. However, a growing number of geological field evidences indicate the preservation or even the reuse of structures inherited from the rifting phase preceding convergence and collision within orogens. By conducting a geo-thermochronometric study of the easternmost, inverted hyperextended Aptian-Cenomanian rift system (Agly massif, North Pyrenean Zone) and the adjacent early retroforeland (Rennes-les-Bains syncline, Aquitaine Basin), this thesis aims to describe the evolution of a distal rifted margin during the first stages of convergence, to quantify the associated source-to-sink processes and to provide temporal and paleogeographic constraints regarding the creation of the very first Pyrenean reliefs resulting from inversion of the margin. Using the zircon and apatite (U-Th)/He multi-thermochronometers, I show that the Pyrenean retro-wedge records two clear phases of orogenic cooling, Late Campanian-Maastrichtian and Ypresian-Bartonian, which I relate to early inversion of the distal rifted margin and main collision, respectively. I have thus been able to propose a crustal-scale sequentially restored model for the tectonic and thermal transition from extension to peak orogenesis in the eastern Pyrenees, which suggests that both thrusting and underplating processes contributed to early inversion of the Aptian-Cenomanian rift system. The absence of Paleocene cooling record indicates little to no erosion of the Pyrenean retro-wedge, suggesting the existence of a more easterly source area supplying early retroforeland sediments at this time. To characterize this eastern edifice, which has since been destroyed by the Oligocene-Miocene opening of the Gulf of Lion, I used in situ (U-Th)/He - U/Pb double dating on detrital zircons and show rapid denudation rates during early convergence, characteristic of early topographic growth. This work shows for the first time clearly the progressive migration of deformation from east to west by inversion of inherited structures at the beginning of Pyrenean convergence. This suggests the existence of an open domain in the east at the end of the rifting phase preceding convergence. This study highlights the role of the architecture of hyper-thinned systems in the formation of collisional orogens and confirms the close links between an orogen and its foreland basins.
824

Problemas direto e inverso de processos de separação em leito móvel simulado mediante mecanismos cinéticos de adsorção / Direct and inverse problems of separation processes moving bed simulated by kinetic mechanisms of adsorption

Kamilla Vogas Romualdo 21 December 2012 (has links)
Diversas aplicações industriais relevantes envolvem os processos de adsorção, citando como exemplos a purificação de produtos, separação de substâncias, controle de poluição e umidade entre outros. O interesse crescente pelos processos de purificação de biomoléculas deve-se principalmente ao desenvolvimento da biotecnologia e à demanda das indústrias farmacêutica e química por produtos com alto grau de pureza. O leito móvel simulado (LMS) é um processo cromatográfico contínuo que tem sido aplicado para simular o movimento do leito de adsorvente, de forma contracorrente ao movimento do líquido, através da troca periódica das posições das correntes de entrada e saída, sendo operado de forma contínua, sem prejuízo da pureza das correntes de saída. Esta consiste no extrato, rico no componente mais fortemente adsorvido, e no rafinado, rico no componente mais fracamente adsorvido, sendo o processo particularmente adequado a separações binárias. O objetivo desta tese é estudar e avaliar diferentes abordagens utilizando métodos estocásticos de otimização para o problema inverso dos fenômenos envolvidos no processo de separação em LMS. Foram utilizados modelos discretos com diferentes abordagens de transferência de massa, com a vantagem da utilização de um grande número de pratos teóricos em uma coluna de comprimento moderado, neste processo a separação cresce à medida que os solutos fluem através do leito, isto é, ao maior número de vezes que as moléculas interagem entre a fase móvel e a fase estacionária alcançando assim o equilíbrio. A modelagem e a simulação verificadas nestas abordagens permitiram a avaliação e a identificação das principais características de uma unidade de separação do LMS. A aplicação em estudo refere-se à simulação de processos de separação do Baclofen e da Cetamina. Estes compostos foram escolhidos por estarem bem caracterizados na literatura, estando disponíveis em estudos de cinética e de equilíbrio de adsorção nos resultados experimentais. De posse de resultados experimentais avaliou-se o comportamento do problema direto e inverso de uma unidade de separação LMS visando comparar os resultados obtidos com os experimentais, sempre se baseando em critérios de eficiência de separação entre as fases móvel e estacionária. Os métodos estudados foram o GA (Genetic Algorithm) e o PCA (Particle Collision Algorithm) e também foi feita uma hibridização entre o GA e o PCA. Como resultado desta tese analisouse e comparou-se os métodos de otimização em diferentes aspectos relacionados com o mecanismo cinético de transferência de massa por adsorção e dessorção entre as fases sólidas do adsorvente. / Several important industrial applications involving adsorption processes, citing as an example the product purification, separation of substances, pollution control and moisture among others. The growing interest in processes of purification of biomolecules is mainly due to the development of biotechnology and the demand of pharmaceutical and chemical products with high purity. The simulated moving bed (SMB) chromatography is a continuous process that has been applied to simulate the movement of the adsorbent bed, in a countercurrent to the movement of liquid through the periodic exchange of the positions of input and output currents, being operated so continuous, notwithstanding the purity of the outlet streams. This is the extract, rich in the more strongly adsorbed component, and the raffinate, rich in the more weakly adsorbed component, the method being particularly suited to binary separations. The aim of this thesis is to study and evaluate different approaches using stochastic optimization methods for the inverse problem of the phenomena involved in the separation process in LMS. We used discrete models with different approaches to mass transfer. With the benefit of using a large number of theoretical plates in a column of moderate length, in this process the separation increases as the solute flowing through the bed, i.e. as many times as molecules interact between the mobile phase and stationary phase thus achieving the equilibrium. The modeling and simulation verified in these approaches allowed the assessment and identification of the main characteristics of a separation unit LMS. The application under consideration refers to the simulation of the separation of Ketamine and Baclofen. These compounds were chosen because they are well characterized in the literature and are available in kinetic studies and equilibrium adsorption on experimental results. With the results of experiments evaluated the behavior of the direct and inverse problem of a separation unit LMS in order to compare these results, always based on the criteria of separation efficiency between the mobile and stationary phases. The methods studied were the GA (Genetic Algorithm) and PCA (Particle Collision Algorithm) and we also made a hybridization between the GA and PCA. This thesis, we analyzed and compared the optimization methods in different aspects of the kinetic mechanism for mass transfer between the adsorption and desorption of the adsorbent solid phases.
825

Application de la spectrométrie de masse COINTOF à l'étude de la dissociation de petits agrégats d'eau protonés par collision sur un atome d'argon : développement d'une cible de nano-gouttes de gaz rare / Collision induced dissociation of protaned water clusters studies with the COINTOF mass spectrometry technique : development of a target of rare gas droplets

Buridon, Victor 13 December 2013 (has links)
L'étude de l'irradiation dans le système moléculaire à l'échelle du nanomètre est un domaine d'investigation innovant des sciences des radiations. Le Dispositif d'Irradiation d'Agrégats Moléculaires (DIAM) est conçu en vue les conséquences de l'irradiation dans des petits systèmes moléculaires modèles comme les agrégats d'eau protonés. L'irradiation provoque la fragmentation en plusieurs fragments neutres ou chargés. La technique de spectrométrie de masse COINTOF (Correlated Ion and Neutral Time of Flight) permet la détection corrélées des fragments neutres et chargés issus de la dissociation d'un système moléculaire préalablement sélectionné en masse et en vitesse. Les données collectées sont traitées et structurées pour permettre l'analyse statistique des corrélations sur un grand nombre d'événements de fragmentation. Parallèlement à l'identification des canaux de fragmentation, la technique COINTOF permet la mesure de leur rapport de branchement et de leur section efficace. La méthode est présentée pour la dissociation induite par collision sur un atome d'argon, d'agrégats d'eau protonés H+(H2O)n:[2;7], accélérés à 8keV. L'efficacité de détection, information déterminante pour la production de données quantitatives, est mesurée à partir des données et étudiée en fonction de la distribution l'amplitude des signaux de détection. Enfin, un nouveau système de cible constituée de nanogouttes de gaz rares a été développé / The study of irradiation in molecular systems at the nanometer scale is an innovative field of research in radiation sciences. The DIAM set-up (Dispositif d'Irradiation d'Agrégats Moléculaires) is designed in order to observe and to characterize the consequences of radiation action on model molecular nanosystems such as protonated water clusters. Irradiation induces the fragmentation of the nanosystem in several neutral and charged fragments. The COINTOF (Correlated Ion and Neutral fragments Time of Flight) mass spectrometry techniques allows the correlated detection of the neutral and charged fragments resulting from the dissociation of a mass and velocity selected molecular system. The data processing is performed before the statistical analysis of the fragment production over a large number of fragmentation events. In parallel with the fragmentation channel identification, branching ratio and cross sections are measured with the COINTOF technique. The method is presented here for the collision induced dissociation on argon atoms of protonated water clusters H+(H2O)n, n=2-7, accelerated at 8keV. The detection efficiency, key parameter for the production of quantitative results, is measured from the set of data itself and studied as a function of the amplitude distribution of the detection signal. Finally, a new set-up for production of rare-gas nanodroplets target has been developed
826

Problemas direto e inverso de processos de separação em leito móvel simulado mediante mecanismos cinéticos de adsorção / Direct and inverse problems of separation processes moving bed simulated by kinetic mechanisms of adsorption

Kamilla Vogas Romualdo 21 December 2012 (has links)
Diversas aplicações industriais relevantes envolvem os processos de adsorção, citando como exemplos a purificação de produtos, separação de substâncias, controle de poluição e umidade entre outros. O interesse crescente pelos processos de purificação de biomoléculas deve-se principalmente ao desenvolvimento da biotecnologia e à demanda das indústrias farmacêutica e química por produtos com alto grau de pureza. O leito móvel simulado (LMS) é um processo cromatográfico contínuo que tem sido aplicado para simular o movimento do leito de adsorvente, de forma contracorrente ao movimento do líquido, através da troca periódica das posições das correntes de entrada e saída, sendo operado de forma contínua, sem prejuízo da pureza das correntes de saída. Esta consiste no extrato, rico no componente mais fortemente adsorvido, e no rafinado, rico no componente mais fracamente adsorvido, sendo o processo particularmente adequado a separações binárias. O objetivo desta tese é estudar e avaliar diferentes abordagens utilizando métodos estocásticos de otimização para o problema inverso dos fenômenos envolvidos no processo de separação em LMS. Foram utilizados modelos discretos com diferentes abordagens de transferência de massa, com a vantagem da utilização de um grande número de pratos teóricos em uma coluna de comprimento moderado, neste processo a separação cresce à medida que os solutos fluem através do leito, isto é, ao maior número de vezes que as moléculas interagem entre a fase móvel e a fase estacionária alcançando assim o equilíbrio. A modelagem e a simulação verificadas nestas abordagens permitiram a avaliação e a identificação das principais características de uma unidade de separação do LMS. A aplicação em estudo refere-se à simulação de processos de separação do Baclofen e da Cetamina. Estes compostos foram escolhidos por estarem bem caracterizados na literatura, estando disponíveis em estudos de cinética e de equilíbrio de adsorção nos resultados experimentais. De posse de resultados experimentais avaliou-se o comportamento do problema direto e inverso de uma unidade de separação LMS visando comparar os resultados obtidos com os experimentais, sempre se baseando em critérios de eficiência de separação entre as fases móvel e estacionária. Os métodos estudados foram o GA (Genetic Algorithm) e o PCA (Particle Collision Algorithm) e também foi feita uma hibridização entre o GA e o PCA. Como resultado desta tese analisouse e comparou-se os métodos de otimização em diferentes aspectos relacionados com o mecanismo cinético de transferência de massa por adsorção e dessorção entre as fases sólidas do adsorvente. / Several important industrial applications involving adsorption processes, citing as an example the product purification, separation of substances, pollution control and moisture among others. The growing interest in processes of purification of biomolecules is mainly due to the development of biotechnology and the demand of pharmaceutical and chemical products with high purity. The simulated moving bed (SMB) chromatography is a continuous process that has been applied to simulate the movement of the adsorbent bed, in a countercurrent to the movement of liquid through the periodic exchange of the positions of input and output currents, being operated so continuous, notwithstanding the purity of the outlet streams. This is the extract, rich in the more strongly adsorbed component, and the raffinate, rich in the more weakly adsorbed component, the method being particularly suited to binary separations. The aim of this thesis is to study and evaluate different approaches using stochastic optimization methods for the inverse problem of the phenomena involved in the separation process in LMS. We used discrete models with different approaches to mass transfer. With the benefit of using a large number of theoretical plates in a column of moderate length, in this process the separation increases as the solute flowing through the bed, i.e. as many times as molecules interact between the mobile phase and stationary phase thus achieving the equilibrium. The modeling and simulation verified in these approaches allowed the assessment and identification of the main characteristics of a separation unit LMS. The application under consideration refers to the simulation of the separation of Ketamine and Baclofen. These compounds were chosen because they are well characterized in the literature and are available in kinetic studies and equilibrium adsorption on experimental results. With the results of experiments evaluated the behavior of the direct and inverse problem of a separation unit LMS in order to compare these results, always based on the criteria of separation efficiency between the mobile and stationary phases. The methods studied were the GA (Genetic Algorithm) and PCA (Particle Collision Algorithm) and we also made a hybridization between the GA and PCA. This thesis, we analyzed and compared the optimization methods in different aspects of the kinetic mechanism for mass transfer between the adsorption and desorption of the adsorbent solid phases.
827

Géodynamique du bassin de Sivas (Turquie) : de la fermeture d’un domaine océanique à la mise en place d’un avant-pays salifère / Geodynamics of the Sivas basin (Turkey) : from oceanic closure to a salt foreland

Legeay, Étienne 13 October 2017 (has links)
L’Anatolie fait partie d’un vaste domaine orogénique qui s’étend des Alpes à l’Himalaya. Les sutures ophiolitiques rencontrées marquent les cicatrices de plusieurs domaines océaniques (branches de la Néotéthys Nord), interdigités entre plusieurs blocs crustaux au cours du Mésozoïque. La fermeture de ces domaines au Crétacé supérieur est accompagnée de la mise en place de bassins tertiaires syn-orogéniques dont fait partie le Bassin de Sivas, limité au nord par le bloc du Kırşehir et au Sud par les Taurides. Une étude structurale de terrain, complétée d’analyses géochimiques, biostratigraphiques et thermochronologiques ainsi que l’étude de 700 km de lignes sismiques 2D inédites, a été menée pour tenter de comprendre (i) le contexte géodynamique régional et (ii) l’architecture tectono-sédimentaire de ce bassin.L’étude des ophiolites présentes le long de la bordure sud du Bassin de Sivas met en évidence des péridotites intensément serpentinisées. La partie supérieure de l’ophiolite présente des brèches et ophicalcites caractéristiques de l’exhumation mantellique, alors que l’analyse géochimique des corps magmatiques révèle un environnement de supra-subduction, daté à circa 90 Ma (U-Pb sur zircon). Ces analyses démontrent la présence d’un domaine océanique embryonnaire entre le Kırşehir et les Taurides, dont la fermeture s’initie le long d’ancienne failles de détachement. L’obduction de la nappe de péridotite et de son mélange frontal sur la marge Nord des Taurides entre le Turonien et le Maastrichtien, permet de former le « socle ophiolitique » commun aux bassins est-anatoliens. L’analyse détaillée de la partie centrale du bassin, en carte et à l’aide de lignes sismiques 2D inédites et de thermochronologie basse température [AFTA et (U-Th)/sur apatite], a permis de proposer un modèle d’évolution cinématique sur la base de coupes équilibrées. La propagation de la déformation vers le Nord, initiée dès l’Eocène inférieur, permet l’isolation progressive du bassin et une forte accumulation d’évaporites à l’Eocène supérieur. Les dépôts de l’Oligo-miocène sont ensuite contrôlés par l’halocinèse, permettant la mise en place de deux générations de mini-bassins salifère, séparés d’une canopée. Les géométries dans le domaine halocinétique, et les variations latérales dans le bassin, montrent le contrôle exercé par (i) le bassin pré-évaporite affleurant le long de la moitié sud du bassin et (ii) l’épaisseur du niveau de sel initial.L’intégration de ces observations à l’échelle régionale met en évidence un contrôle du raccourcissement crustal, dans les Taurides et les bassins tertiaires, lié à la fermeture de la Néotéthys Sud, en générant l’émergence de structures de socles. La collision enregistrée à l’Oligocène supérieur - Miocène lors de l’indentation de la plaque Arabe le long des Taurides est contemporaine de la déformation du Bassin de Sivas et des bassins adjacents. / Anatolia is part of a vast orogenic domain that extends from the Alps to the Himalayas. Numerous ophiolitic sutures defined the remnants of several oceanic domains (Northern and southern Neotethys), between continental fragments formed during Mesozoic time. Oceanic closure during Late Cretaceous is recorded by the establishment of syn-orogenic tertiary basins, including the Sivas Basin bounded to the north by the Kırşehir block and to the south by the Taurides. An extended study based on field and completed by geochemistry, biostratigraphy and thermochronology analyzes and more than 700 km unpublished seismic data, was conducted to resolve (i) the regional geodynamic context and (ii) the tectono-sedimentary architecture of this basin.The ophiolites located along the southern edge of the Sivas Basin are made of serpentinized peridotites. The upper part of the ophiolite present breccias and ophicalcites commonly described as associated to mantle exhumation environment, while the geochemical analysis of the magmatic bodies reveals a supra-subduction environment dated at circa 90 Ma (U-Pb on zircon). These observations are in agreement with an embryonic ocean domain located between the Kırşehir and the Taurides, the closure which was initiated along fossil detachment faults. The obduction of the peridotite nappe and its frontal mélange on the northern margin of the Taurides between the Turonian and the Maastrichtian allows forming the “ophiolitic basement” of the east-anatolian basins.A detailed map and cross-section analysis, supported by 2D seismic lines and low-temperature thermochronology [AFTA and (U-Th) / on apatite], resulted in a kinematic evolution model and the realization of balanced cross-sections. The propagation of the deformation towards the north, initiated in the Lower Eocene, results in the progressive isolation of the basin and a strong accumulation of evaporites during the Upper Eocene. The Oligo-Miocene depocenters were controlled by halokinesis, forming two generations of mini-basins, separated by a salt canopy. The geometries in the halokinetic domain and the lateral variations in the basin show the control exerted by (i) the pre-evaporite basin outcropping along the southern half of the basin and (ii) the thickness of the initial salt level.Integration at the regional scale within the Taurides highlights the propagation of crustal shortening related to the Southern Neotethys closure, which formed linear tectonic basement exhumation. The collision recorded in the Upper Oligocene - Miocene during the indentation of the Arabic plate along the Taurides is contemporaneous to the deformation the Sivas Basin.
828

Calcul des coefficients de transport dans des plasmas hors de l'équilibre / Calculation of transport coefficients in plasmas out of equilibrium

Mahfouf, Ali 18 July 2016 (has links)
Les propriétés de transport à haute température dans les gaz et/ou dans les plasmas ont une importance capitale dans différents domaines, à savoir dans le domaine de technologie de coupure à arc, plasmas de coupure, de soudure ou de gravure. La connaissance des coefficients de transport est nécessaire pour toute modélisation faisant intervenir les équations hydrodynamiques. Dans le cadre de la théorie cinétique des gaz dilués, une solution approchée de l’équation intégro-différentielle de Boltzmann régissant les fonctions de distribution a été proposée par Chapman-Enskog. Les coefficients de transport sont calculés classiquement par la méthode de Chapman-Enskog via les intégrales de collision. Dans le cadre de notre étude nous avons développé, dans un premier temps, un code numérique permettant l’obtention de ces intégrales de collision en tenant compte des singularités qui peuvent apparaître dans le calcul des sections efficaces relatives aux interactions entre les particules constituant les gaz et/ou les plasmas. Dans un second temps nous avons étudié l’influence du choix des paramètres des potentiels d’interaction sur les coefficients de transport. Par la suite, nous avons utilisé le code numérique ainsi développé pour évaluer les coefficients de transport du plasma d’hélium en étudiant l’influence du choix de la méthode de calcul de composition chimique sur ces coefficients. Enfin, un modèle simplifié d’une interaction entre une onde électromagnétique et un plasma d’hélium a été proposé comme une application directe des coefficients de transport. / Transport properties at high temperature in gases and/or in plasmas are of very importance in various fields, namely in the field of breaking technology in arc, cutting plasma, welding or burning. Knowledge of transport coefficients is necessary for any modeling involving hydrodynamic equations. As part of the kinetic theory of diluted gas, an approximate solution of the integro-differential Boltzmann equation governing distribution functions was proposed by Chapman-Enskog. Transport coefficients are classically computed using the method of Chapman-Enskog through the collision integrals. In our study we have developed, initially, a numerical code to obtain these collision integral taking into account the singularities that may occur in the calculation of the cross sections relating to interactions between particles forming the gas and/or plasmas. Secondly, we have studied the influence of the choice of parameters of interaction potentials on transport coefficients. Subsequently, we have used the numerical code developed for evaluating and helium plasma transport coefficients by studying the influence of the choice of method for calculating chemical composition on these coefficients. Finally, a simplified model of an interaction between an electromagnetic wave and a helium plasma has been proposed as a direct application of the transport coefficients.
829

Právní souvislosti nočních dopravních nehod s chodci / Legal Context of Nightime Road Accidents with Pedestrians

Daněk, Vladimír January 2017 (has links)
The thesis „Legal Context of Night-time Road Accidents with Pedestrian „deals with the interpretation of legal decisions on traffic accidents caused by the vehicle during the night and where the other participant was a pedestrian. The main aim of this thesis is to find the established limits for the assessing of blame in comparable accident situations in cases of traffic accidents of the vehicle and the pedestrian at the reduced visibility with emphasis on the assessing in relation to the circumstances of the cases from the technical and legal point of view and in relation to the health consequences. Legal interpretations of the law are defined within the theoretical part of the thesis with emphasis on the ones which appear repeatedly in the judicial decisions. Approximately 1530 judicial decisions were studied and analysed in the analytical part, of which 56 were selected, that corresponds to the requirements of this thesis. There are also 5 expert evidences provided by the Institute of Forensic Engineering of Brno University of Technology. In the above mentioned cases there were defined the limits for the assessing of accidents based on which the judicial decision was predicted in context with the defined established limits for the judicial decisions at the top of the court hierarchy.
830

Caractérisation d’auto-assemblages de polyoxométallates hybrides organiques-inorganiques par spectrométrie de mobilité ionique couplée à la spectrométrie de masse / Characterization of self-assemblies of organic-inorganic hybrid polyoxometalates by ion mobility spectrometry coupled to mass spectrometry

Hupin, Sébastien 03 December 2018 (has links)
Les polyoxométallates (POM) sont des composés anioniques constitués par l’assemblage de polyèdres d’oxydes métalliques {MOy}, (avec M, MoVI ou WVI) reliés entre eux par des atomes d'oxygène. Les POM forment ainsi une classe remarquable de clusters d’oxydes métalliques inorganiques nanométriques, avec une grande variété de charges et de structures. Il est possible de former des systèmes hybrides incluant la partie inorganique du POM et une partie organique greffée, permettant d’apporter de nouvelles fonctionnalités aux POM, tel que l’auto-assemblage. Nous avons consacré ces travaux de thèse à la caractérisation de systèmes classiques, hybrides et auto-assemblés de POM par spectrométrie de masse couplée à la spectrométrie à la mobilité ionique (IMS-MS). Une première approche expérimentale par spectrométrie de mobilité ionique en tube de dérive (DTIMS) nous a permis de déterminer les sections efficaces de collisions (CCS) de POM étalons dans l’hélium et dans l’azote. Les CCS des étalons POM nous ont ensuite permis d’étalonner une cellule IMS de type Travelling Wave (TWIMS). L’analyse par IMS-MS de POM hybrides organiques-inorganiques seuls ou en présence de PdCl2 a mis en évidence la présence de systèmes auto-assemblés triangulaires [POM3·cation3], carrés [POM4·cation4] ou pentagonaux [POM5·cation5] avec différents états de charges. Des valeurs de CCS de ces auto-assemblages ont également pu être estimées à partir de l’étalonnage de la cellule TWIMS. Par une approche théorique, nous avons modélisé plusieurs structures de POM standards avec et sans contre-ion tetrabutylammonium (TBA+) par la théorie de la fonctionnelle de la densité (DFT). Les structures optimisées ont été utilisées afin de déterminer des CCS théoriques grâce au logiciel MOBCAL, auquel nous avons incorporé les atomes de molybdène et de tungstène pour lesquels nous avons optimisé de nouveaux paramètres de potentiel de Lennard Jones. La correspondance des CCS expérimentales et théoriques des structures de POM standards offre de nouvelles possibilités pour une attribution structurale pour les POM hybrides auto-assemblés par coordination en présence de cations métalliques. / Polyoxometalates (POM) are anionic compounds formed by the assembly of metal oxide polyhedra {MOy}, (with M, MoVI or WVI) linked together by oxygen atoms. POM thus form a remarkable class of nanometric inorganic metal oxide clusters, with a wide variety of charges and structures. It is possible to form hybrid systems including the inorganic part of the POM and a grafted organic part, allowing new functionalities to be added to the POM, such as selfassembly. We have dedicated this thesis work to the characterization of standards, hybrid and self-assembled POM systems by mass spectrometry coupled to ion mobility spectrometry (IMS-MS). A first experimental approach using drift tube ion mobility spectrometry (DTIMS) allowed us to determine the collision cross sections (CCS) of standard POM in helium and nitrogen. The CCS of the POM standards then allowed us to calibrate an IMS cell of a Travelling Wave ion mobility instrument (TWIMS). The analysis by IMS-MS of organic-inorganic hybrid POMs alone or in the presence of transition metal cations revealed the presence of self-assembled triangular [POM3·cation3], square [POM4·cation4] or pentagonal [POM5·cation5] systems with different charge states. CCS values of these self-assemblies was estimated from the calibration of the TWIMS cell. Using a theoretical approach, we modelled several standard POM structures with and without tetrabutylammonium counterion (TBA+) using density functional theory (DFT). The optimized structures were used to determine theoretical CCS using the trajectory method of the MOBCAL software, in which we incorporated molybdenum and tungsten atoms for which we optimized new Lennard Jones potential parameters. The correspondence of experimental and theoretical CCS of standard POM structures offers new possibilities for structural attribution of self-assembled hybrid POM by coordination in the presence of metal cations.

Page generated in 0.0752 seconds