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Coherent structures and impact of the external thermal stratification in a transitional natural convection vertical channel / Structure cohérentes et impact de la stratification extérieure dans un écoulement de convection naturelle en canal verticalThebault, Martin 05 December 2018 (has links)
Dans les écoulements de convection naturelle en canal, de nombreuses structures cohérentes se développent. Leur rôle dans les transferts de masse et de chaleurs reste aujourd’hui mal connu. Des études numériques basées sur des Simulations aux Grandes Echelles d’un canal vertical dont un des côtés est chauffé uniformément à flux constant ont donc été entreprises. Différentes étapes de la transition laminaire-turbulente sont identifiées et deux bandes de fréquences sont observées en proche paroi chauffée. Une méthode, basée sur la Proper Orthogonal Decomposition (POD), a aussi été utilisée et a permis une très nette séparation spatio-temporelle des modes les plus énergétiques de l’écoulement en fonction des fréquences précédemment identifiées. Il devient donc possible d’étudier la contribution de ces modes à l’écoulement. Une analyse POD des champs de vitesses expérimentaux permet l’identification de similarités avec les structures observées numériquement.Les variations du gradient de température extérieur au canal, ont été identifiées comme l’une des sources de ces différences et ont fait l’objet d’études expérimentales et numériques. Il est montré qu’un augmentation du gradient positif de température diminue le débit mais aussi déplace la transition plus bas dans le canal. Les études numériques permettent également d’étudier le cas de gradients de température faibles ou négatifs, gradients qui sont difficile à obtenir expérimentalement. Un modèle théorique de l’influence de la stratification extérieure sur le débit massique induit est aussi développé. L’accord entre les résultats prédits et les résultats expérimentaux et numériques est excellent. Ce dernier point souligne que la stratification thermique est un facteur clé dans ce type d’écoulement et que son influence est précisément quantifiée dans ce travail / In natural convective flows, complex coherent structures develop whose the role in heat and mass transfer are not well understood. A numerical study, based on Large-Eddy-Simulations of a vertical channel with one side uniformly was therefore carried out. Different stages of transitional flow development were identified numerically with two characteristic frequency bands being observed in the flow, near the heated wall. Methods derived from the Proper Orthogonal Decomposition (POD) was also used and allows the most energetic modes to be separated accordingly to two characteristic frequency bands found numerically. As result, the contribution of the two families of modes to the near wall turbulent heat transfer and velocity-temperature correlation has been evaluated. POD was also performed on experimental measurements showing similarities with the numerically observed structures.In this work, variations of the external thermal stratification have been identified as one possible source of these differences and its influence was therefore investigated experimentally and numerically. It is shown that the increase in the positive gradient of the external stratification not only decreases the mass flow rate but also displaces the transition height to a lower location in the channel. Numerical simulations also allow the study of cases of weak and negative thermal stratifications which are difficult to achieve in laboratories. A theoretical model of the influence of the external thermal stratification on the mass flow rate was also developed. There is an excellent agreement between the theoretical predictions and the experimentally and numerically obtained mass flow rates. This clearly highlights that external temperature distributions are key driving factors and their influence is accurately quantified in this work
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An adaptive model order reduction for nonlinear dynamical problems. / Um modelo de redução de ordem adaptativo para problemas dinâmicos não-lineares.Nigro, Paulo Salvador Britto 21 March 2014 (has links)
Model order reduction is necessary even in a time where the parallel processing is usual in almost any personal computer. The recent Model Reduction Methods are useful tools nowadays on reducing the problem processing. This work intends to describe a combination between POD (Proper Orthogonal Decomposition) and Ritz vectors that achieve an efficient Galerkin projection that changes during the processing, comparing the development of the error and the convergence rate between the full space and the projection space, in addition to check the stability of the projection space, leading to an adaptive model order reduction for nonlinear dynamical problems more efficient. This model reduction is supported by a secant formulation, which is updated by BFGS (Broyden - Fletcher - Goldfarb - Shanno) method to accelerate convergence of the model, and a tangent formulation to correct the projection space. Furthermore, this research shows that this method permits a correction of the reduced model at low cost, especially when the classical POD is no more efficient to represent accurately the solution. / A Redução de ordem de modelo é necessária, mesmo em uma época onde o processamento paralelo é usado em praticamente qualquer computador pessoal. Os recentes métodos de redução de modelo são ferramentas úteis nos dias de hoje para a redução de processamento de um problema. Este trabalho pretende descrever uma combinação entre POD (Proper Orthogonal Decomposition) e vetores de Ritz para uma projecção de Galerkin eficiente que sofre alterações durante o processamento, comparando o desenvolvimento do erro e a taxa de convergência entre o espaço total e o espaço de projeção, além da verificação de estabilidade do espaço de projeção, levando a uma redução de ordem do modelo adaptativo mais eficiente para problemas dinâmicos não-lineares. Esta redução de modelo é assistida por uma formulação secante, que é atualizado pela formula de BFGS (Broyden - Fletcher- Goldfarb - Shanno) com o intuito de acelerar a convergência do modelo, e uma formulação tangente para a correção do espaço de projeção. Além disso, esta pesquisa mostra que este método permite a correção do modelo reduzido com baixo custo, especialmente quando o clássico POD não é mais eficiente para representar com precisão a solução.
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A Hierarchical POD Reduction Method of Finite Element Models with Application to Simulated Mechanical SystemsBjörklund, Martin January 2012 (has links)
When simulating mechanical systems the flexibility of the components often has to be taken into account. This is particularly important for simulations when high detailed information is demanded, e.g. to calculate stresses. To this end the Finite Element Method (FEM) is often used. However the models can become very large, containing millions of degrees of freedom. Solving large linear systems are computationally demanding. Therefore ways of reducing the problem is often sought. These reduction does, however, remove much of the details that was to be investigated. In this thesis this problem is addressed by creating a reduction scheme, using Proper Orthogonal Decomposition (POD), that significantly reduces a problem but still captures much of the details. A novel method for enriching regular POD-based model reduction methods with hierarchically determined enrichment POD-modes is developed. The method is proposed and validated in a FEM application towards dynamical simulation. The enriched method is compared against a regular POD reduction technique. An numerical study is made of a model example of linear elasticity in a gearwheel. The numerical study suggests that the error of displacements is around ten times smaller, on average, when using the enriched basis compared to a reference basis of equal dimensionality consisting of only regular POD modes. Also it is shown that local quantities as the von Mises stress in a gearwheel tooth is preserved much better using the enriched basis. An a posteriori error estimate is proposed and proved for the static case, showing that the error is bound. / När man simulerar mekaniska system så måste man ofta ta hänsyn till de ingående komponenternas flexibilitet. Detta är särskilt viktigt då man gör simuleringar med krav på hög detaljkännedom, såsom mätningar av spänningar i kugghjul etc. Till detta ändamål används ofta en Finit Element Metod (FEM). Dock kan modellerna ofta bli väldigt stora, med över en miljon frihetsgrader. Att lösa linjära system av den storleken är beräkningsmässigt krävande. Därför är det naturligt att försöka reducera problemen. Reduktion innebär dock att information försvinner, i synnerhet de detaljer som skulle beräknas. I detta examensarbete så behandlas problemet genom att skapa en ny metod för reducering av stora finita element modeller. Metoden bygger på tidigare kunskap om Proper Orthogonal Decomposition (POD) som ett sätt att reducera modeller. Den nya metoden reducerar finita ellement modeller samtidigt som den bibehåller hög detalj. En ny metod utvecklas för att berika en vanlig POD-baserad modellreduktion med hjälp av hieraktiskt bestämda berikningsmoder. Metoden beskrivs och testas i en dynamisk FEM-applikation av elasticitet i ett kugghjul i 2 dimensioner. Metoden för berikning jämförs numeriskt med en metod som använder vanlig POD-reduktion. Körningar visar att felet i den berikade metoden är omkring 10 gånger mindre, i genomsnitt, jämfört med en vanlig metod. Det visas också att spänningar bevaras på ett mycket bra sätt med den nya berikningsmetoden. Dessutom så formuleras och bevisas ett a posteriori estimat för statiska lastfall, vilket innebär att felet i metoden är bundet.
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Investigation et application des méthodes d'ordre réduit pour les calculs d'écoulements dans les faisceaux tubulaires d'échangeurs de chaleurPomarede, Marie 07 February 2012 (has links) (PDF)
Cette thèse s'intéresse à la faisabilité de la mise en place de modèles d'ordre réduit pour l'étude des vibrations sous écoulement au sein de faisceaux tubulaires d'échangeurs de chaleur. Ces problématiques sont cruciales car les systèmes étudiés sont des éléments majeurs des centrales nucléaires civiles et des chaufferies embarquées dans les sous-marins.Après avoir rappelé le fonctionnement et les risques vibratoires existants au sein des échangeurs de chaleur, des calculs complets d'écoulement et de vibrations sous écoulement ont été effectués, d'abord pour un tube seul en milieu infini, puis pour un faisceau de tubes. Ces calculs ont été menés avec l'outil CFD Code_Saturne. La méthode de réduction de modèle POD (Proper Orthogonal De-composition) a été appliquée au cas des écoulements avec la structure laissée fixe.Les résultats obtenus montrent l'efficacité de la méthode pour ces configurations, moyennant l'introduction de méthodes de stabilisation pour l'écoulement au sein du faisceau. La méthode POD-multiphasique, permettant d'adapter la méthode POD à l'interaction fluide-structure, a ensuite été appliquée. Les grands déplacements d'un cylindre seul dans la zone d'accrochage (lock-in) ont été correctement reproduits par cette méthode de réduction de modèle. De même, on montre que les grands déplacements d'un cylindre en milieu confiné dans un faisceau de tubes sont fidèlement reconstruits.Enfin, l'extension de l'utilisation de la réduction de modèle aux études d'évolution paramétrique a été testée. Nous avons d'abord utilisé la technique considérant une base POD unique pour reproduire des écoulements à divers nombres de Reynolds autour d'un cylindre seul. Les résultats confirment la prédictivité bornée à une gamme de paramètres de cette méthode. Enfin, l'interpolation de bases POD pré-calculées pour une famille de paramètres donnés, utilisant les variétés de Grassmann et permettant de générer de nouvelles bases POD, a été testée sur des cas modèles.
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Envolvimento da peroxidase e polifenoloxidase no bloqueio xilemático de hastes de ave-do-paraíso (Strelitzia reginae) / Involvment of peroxidase and polyliphenoloxyidase in the vascular occlusion of stalks of bird-of-paradise (Strelitzia reginae)Karsten, Juliane 16 February 2009 (has links)
Made available in DSpace on 2015-03-26T13:36:39Z (GMT). No. of bitstreams: 1
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Previous issue date: 2009-02-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The goals of this work were to determine the time in which occurs the vascular occlusion and the contribution of the peroxidase (POD) and polyphenoloxidase (PPO) in this process; partially purify and characterize these enzymes and verify the effect of the use of enzymatic inhibitors combined or not with sucrose in the pulsing solution on the postharvest life of the bird-of-paradise. To determine the time of occlusion, the stalks were dry stored for different periods of time (0, 8, 16, 24, 32, 40 and 48 hours), and after being placed in water. The variation of fresh mass and the relative water content (RWC) of the sepals were evaluated within the first 24 hours, and the POD and PPO activity were determined after 100 hours. Harvested flowers were immediately placed in water and had their fresh mass variation, and POD and PPO activity daily evaluated up to 8th day, when the first floret was complete wilted. Flowers maintained for 16 hours under dry storage recuperated the initial fresh mass index and RWC after being placed in water, suggesting that the vascular occlusion occured after 16 hours of dry storage. The POD activity was higher in control stalks and the PPO was higher in stalks which suffered moderated water stress (16, 24, 32 and 40 hours). Throughout the vase life, the POD activity reached the highest level in the 8th day of vase life, and the PPO was kept constant. The POD activity was higher than the PPO in all the analyses, suggesting a higher influence of the POD in the xylematic occlusion of this specie. In the process of enzymatic characterization, the ideal pH and the optimum temperature for both enzymes were determined, as well as the optimum substrate for the PPO. The stability in different pHs, thermal stability and the effect of different inhibitors were also observed. The highest activity of POD was found in pH 5.0 and 60ºC, and the prexi incubation for 120 minutes in pH 2.5 and 25ºC lead to the inhibition of 93.1% of the initial activity, 120 minutes in 70ºC to 98.7% of inhibition and 80ºC for 10 minutes or 90ºC for 1 minute lead to complete inactivation. A complete inhibition of this enzyme was also achieved in the presence of different inhibitors, like ascorbic acid, L-cysteine, sodium metabissulfite, sodium azide, β-mercaptoethanol and DTT. The PPO presented the highest activity with 4-methylcatecol as substrate, in pH 6.0 and 40ºC. Complete inactivation of this enzyme was obtaining by incubating for 10 minutes at 80ºC or using 1 mM of DTT, L-cisteyne, sodium metabissulfite and β-mercaptoethanol. Finally, different pulsing solutions containing enzymatic inhibitors, combined or not with sucrose 40% were applied for 24 hours. The fresh mass variation, RWC and number of open florets were daily determined, and the longevity was determined until the wilting of the last opened floret. From the inhibitors applied alone, the sodium azide was able to provide the highest values of fresh mass, longest longevity and highest number of open florets. Combined with sucrose, the ascorbic acid and the sodium azide were able to provide the best results, with the highest number of open florets and longer longevity. The occlusion of xylematic vessels of this specie is related to the POD and PPO activity and the use of pulsing solutions containing enzymatic inhibitors is a viable technique to extend the vase life of bird-of-paradise of flowers. / Os objetivos deste trabalho foram: determinar o momento de ocorrência do bloqueio vascular e a contribuição da peroxidase (POD) e polifenoloxidase (PPO) neste processo; purificar parcialmente e caracterizar essas enzimas; e verificar o efeito da utilização de inibidores enzimáticos combinados ou não com sacarose na solução de pulsing sobre a vida pós-colheita de ave-do-paraíso. Para determinar o tempo para a oclusão, hastes florais foram armazenadas a seco por diferentes períodos (0, 8, 16, 24, 32, 40 e 48 horas), e após foram colocadas na água. A variação de massa fresca e o teor relativo de água (TRA) das sépalas foram avaliados nas primeiras 24 horas, e a atividade da POD e PPO foram determinadas após 100 horas. Flores colhidas e colocadas imediatamente na água, tiveram sua variação de massa fresca, e atividade da POD e PPO avaliadas diariamente até o 8º dia, quando o 1º florete estava completamente seco. Flores mantidas por até 16 horas em armazenamento a seco, recuperaram os valores de massa fresca e TRA iniciais após serem mantidas em água, sugerindo que o bloqueio vascular esteja ocorrendo após essas 16 horas. A atividade da POD foi maior em hastes controle e a da PPO em hastes que sofreram estresse hídrico moderado (16, 24, 32 e 40 horas). Ao longo da vida de vaso, a atividade da POD alcançou maiores níveis após o 8º dia da vida de vaso, e a da PPO manteve-se constante. A atividade da POD foi superior a da PPO em todas as análises, sugerindo uma maior influência da POD no bloqueio xilemático desta espécie. No processo de caracterização enzimática, o pH ideal e a temperatura ótima para ambas as enzimas foi determinado, bem como o substrato ótimo para a PPO. A estabilidade a diferentes pHs, estabilidade térmica e o efeito de diferentes inibidores também foram acompanhados. Maior atividade da POD foi encontrada em pH 5,0 e 60ºC, e a pré-incubação por 120 minutos em pH 2,5 a 25ºC levou a inibição de 93,13% da atividade inicial, 120 minutos a 70ºC a 98,69% de inibição, e a 80ºC por 10 minutos ou 90ºC por 1 minuto levou a inativação completa. Uma completa inibição desta enzima também foi encontrada na presença de diferentes inibidores, como ácido ascórbico, L-císteina, metabissulfito de sódio, sódio azida, β-mercaptoetanol e DTT. A PPO apresentou maior atividade com 4-metil-catecol como substrato, em pH 6,0 e 40ºC. Inativação completa desta enzima foi obtida com pré-incubação por 10 minutos a 80ºC ou usando 1 mM de DTT, L-cisteína, metabissulfito de sódio e β-mercaptoetanol. Finalmente, diferentes soluções de pulsing contendo inibidores enzimáticos, combinados ou não com sacarose 40% foram aplicadas por 24 horas. A variação de massa fresca, TRA e o número de floretes abertos foram determinados diariamente, e a longevidade foi acompanhada até o murchamentodo último florete aberto. A partir dos inibidores aplicados sozinhos, o sódio azida foi que proporcionou maiores valores de massa fresca, maior longevidade e maior número de floretes abertos. Combinados com sacarose, o ácido ascórbico e o sódio azida foram capaz de proporcionar os melhores resultados, com maior número de floretes abertos e maior longevidade. O bloqueio dos vasos xilemáticos desta espécie está relacionado à atividade da POD e PPO e o uso de soluções de pulsing contendo inibidores enzimáticos é uma técnica eficiente em prolongar a vida de vaso de flores de ave-doparaíso.
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An adaptive model order reduction for nonlinear dynamical problems. / Um modelo de redução de ordem adaptativo para problemas dinâmicos não-lineares.Paulo Salvador Britto Nigro 21 March 2014 (has links)
Model order reduction is necessary even in a time where the parallel processing is usual in almost any personal computer. The recent Model Reduction Methods are useful tools nowadays on reducing the problem processing. This work intends to describe a combination between POD (Proper Orthogonal Decomposition) and Ritz vectors that achieve an efficient Galerkin projection that changes during the processing, comparing the development of the error and the convergence rate between the full space and the projection space, in addition to check the stability of the projection space, leading to an adaptive model order reduction for nonlinear dynamical problems more efficient. This model reduction is supported by a secant formulation, which is updated by BFGS (Broyden - Fletcher - Goldfarb - Shanno) method to accelerate convergence of the model, and a tangent formulation to correct the projection space. Furthermore, this research shows that this method permits a correction of the reduced model at low cost, especially when the classical POD is no more efficient to represent accurately the solution. / A Redução de ordem de modelo é necessária, mesmo em uma época onde o processamento paralelo é usado em praticamente qualquer computador pessoal. Os recentes métodos de redução de modelo são ferramentas úteis nos dias de hoje para a redução de processamento de um problema. Este trabalho pretende descrever uma combinação entre POD (Proper Orthogonal Decomposition) e vetores de Ritz para uma projecção de Galerkin eficiente que sofre alterações durante o processamento, comparando o desenvolvimento do erro e a taxa de convergência entre o espaço total e o espaço de projeção, além da verificação de estabilidade do espaço de projeção, levando a uma redução de ordem do modelo adaptativo mais eficiente para problemas dinâmicos não-lineares. Esta redução de modelo é assistida por uma formulação secante, que é atualizado pela formula de BFGS (Broyden - Fletcher- Goldfarb - Shanno) com o intuito de acelerar a convergência do modelo, e uma formulação tangente para a correção do espaço de projeção. Além disso, esta pesquisa mostra que este método permite a correção do modelo reduzido com baixo custo, especialmente quando o clássico POD não é mais eficiente para representar com precisão a solução.
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Análise da expressão do fator de transcrição TCF21/POD-1 e de genes do ciclo celular em tumores adrenocorticais humanos. / Analysis of TCF21/POD-1 transcriptor factor and cycle cells genes expression in adult adrenocortical tumors.Barbara dos Santos Passaia 31 May 2016 (has links)
As massas adrenocorticais são majoritariamente (70-80%) adenomas adrenocorticais (ACA). Os carcinomas adrenocorticais (ACC) são mais raros e de prognóstico restrito, com incidência de 1-2 casos por milhão, com alta taxa de reincidência (70-80%). Apesar dos tumores adrenocorticais (ACT) serem raros, no Brasil a incidência desses tumores em crianças é cerca de 10 vezes superior ao do restante do mundo, devido a uma mutação do gene TP53. Atualmente, o diagnóstico de massas adrenocorticais é realizado através dos critérios de Weiss, que possuem limitações, e por isso é intensa a busca de novos marcadores moleculares que facilite o diagnóstico de ACTs. POD-1/ TCF21 é um fator de transcrição do tipo helix-loop-helix básica (bHLH) expresso nos sítios de interação mesênquima-epitélio durante o desenvolvimento embrionário. Em ACTs, POD-1 regula a expressão endógena de SF-1 através da ligação na sequencia E-box da região promotora de SF-1, e nesses tumores parece estar relacionado negativamente com genes reguladores do ciclo celular, como BUB1B. BUB1B é um gene que codifica uma quinase com funções importantes durante o checkpoint mitótico. A expressão de BUB1B é considerada fator de prognóstico em diferentes tipos de tumores, inclusive em ACTs humanos, nos quais a expressão combinada de BUB1B e PINK1 (ΔCtBUB1B - ΔCtPINK1) mostrou-se um bom marcador de sobrevida em pacientes com ACC. PINK1, quinase 1 induzida por PTEN, é regulada principalmente pela mitocôndria, e em ACTs sua expressão está reduzida em ACC mais agressivos. Temos como hipótese que a expressão de POD-1 pode ter valor diferencial no diagnóstico de massas adrenocorticais, e que a análise da expressão combinada de POD-1, BUB1B e PINK1 pode ter valor diferencial para prognóstico de pacientes com ACT. Nesse trabalho foram analisados, por reação de qPCR com sondas Taqman, o cDNA obtido de 130 amostras de tumores: 79 adultos (44 ACAs e 35 ACCs), 35 crianças com menos de 5 anos de idade (27 ACAs e 8 ACCs) e 16 crianças de 5 a 18 anos de idade (6 ACAs e 10 ACCs). Nossos resultados mostram que POD-1 e BUB1B tem valor diferencial em ACT adulto e que a expressão combinada de POD-1 e BUB1B pode ser um marcador de prognóstico em pacientes com carcinoma adulto. Enquanto que, a expressão combinada de POD-1 e SF-1 pode ter valor de diagnóstico em pacientes pediátricos com menos de 5 anos. Em resumo, concluímos que estudos experimentais devem ser realizados para comprovar a relação entre os genes estudados, para que os resultados sejam sólidos o suficiente para serem utilizados no diagnóstico e prognóstico dos tumores adrenocorticais. / The adrenocortical masses are mostly (70-80%) adrenocortical adenomas (ACA). Adrenocortical carcinomas (ACC) are scarce and have limited prognosis, with an incidence of 1-2 cases per million and high recurrence rate (70-80%). Despite adrenocortical tumors (ACT) are rare in Brazil the incidence of these tumors in children is about 10 times higher than the rest of the world, due to a mutation of the TP53 gene. Currently, the diagnosis of adrenocortical mass is carried through Weiss criteria that have limitations, so it is intensive the search for new molecular markers that facilitate the diagnostic of ACTs. TCF21/POD-1 is a transcription factor helix-loop-helix type expressed in mesenchymal-epithelial sites of interaction during embryonic development. In ACTs, POD-1 regulates the expression of endogenous SF-1 through binding the E-box sequence of SF-1 promoter region, and seems to be negatively relates with cell cycle regulatory genes such as BUB1B. BUB1B is a gene encoding a kinase-with important function during mitotic checkpoint. The expression of BUB1B is considered a prognostic factor in different types of tumors, including ACTs. Combined expression of BUB1B and PINK1 (ΔCtBUB1B - ΔCtPINK1) has been shown to be a good marker of survival in adults with ACC, whereas the PINK1 expression is reduced in the most aggressive ACC. We hypothesized that the POD-1 expression may have differential value in the diagnosis of adrenocortical masses, and that the analysis of the combined expression of POD-1, BUB1B and PINK1 may have differential value for the prognosis of patients with ACT. In this work were analyzed by PCRq Taqman probes the cDNA obtained from 130 tumor samples: 79 adults (44 ACAs and 35 ACCs), 35 children under 5 years old (27 ACAs and 8 ACCs) and 16 children 5-18 years of age (6 ACAs and 10 ACCs). Our results show that POD-1 and BUB1B has differential value in adult ACT, and the combined expression of POD-1 and BUB1B may have a prognostic value in patients with adult carcinoma. In addition, the combined expression of POD-1 and SF-1 might have diagnostic value in pediatric patients younger than 5 years. In summary, we conclude that experimental studies should be conducted to confirm the relationship between the genes studied, so that the results are solid enough to be used in the diagnosis and prognosis of adrenocortical tumors.
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Destinační management a jeho praktická aplikace v oblasti Pece pod Sněžkou / Management of destination and its practical application in the area of Pec pod SněžkouČerná, Karolína January 2012 (has links)
The aim of this paper is an evaluation of destination's management in particular czech tourist destination. The paper begins with the theoretical part which explains basic relations and issues in management of destination. Such information is then applied in the practical part on destination Pec pod Sněžkou. It begins with the introduction of the destination. Afterwards are described main subjects, form of their cooperation and results of their activities. The deduction of the paper features an evaluation of destination and it's management and recommendations to the future.
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Méthodologies de réduction de modèles multiphysiques pour la conception et la commande d’une chaîne de traction électrique / Multiphysics model reduction methodologies for the design and control of an electric power trainDa Silva, Frédéric 24 November 2015 (has links)
La simulation numérique occupe une part de plus en plus importante dans les phases de conception mais aussi de validation de systèmes innovants. Dans le cadre de la conception d’une chaîne de traction d’un véhicule électrique, la simulation numérique peut par exemple être employée pour choisir une technologie de moteur électrique ou encore pour mettre au point des stratégies de pilotage au regard de critères de décision tels que l’autonomie du véhicule, son coût mais aussi sa performance.Les systèmes devenant de plus en plus complexes, ils requièrent des simulations de plus en plus fines afin d’appréhender au mieux les phénomènes qu’ils mettent en œuvre - par exemple l’étude des pertes fer dans une machine électrique. L’utilisation de simulations 3D permet d’avoir des résultats très précis à l’échelle d’un organe mais ne se prête pas encore aujourd’hui à l’étude de systèmes de grande taille (c’est-à-dire avec beaucoup de degrés de liberté, de nombreux paramètres d’optimisation et plusieurs domaines de la Physique en jeu). En effet, les simulations 3D sont d’autant plus coûteuses en temps de calcul que le modèle à étudier contient de degrés de liberté. C’est pourquoi, depuis quelques années les techniques de réduction de modèles attisent les développements. En effet, elles permettent de garantir un bon compromis entre le temps de calcul et la précision des résultats produits par les modèles réduits.Nous nous intéressons ici à l’utilisation de ces techniques dans un contexte industriel autour de deux axes : - l’étude de phénomènes thermiques (dans les modules d’électronique de puissance) - l’étude de phénomènes électromagnétiques (dans les machines électriques) / Numerical simulations are widely used during the design phase of a product but also for the validation of an innovative system. For example, during the conception of an electric vehicle’s powertrain, numerical simulations can be used to select the appropriate electric engine technology or for the development of control strategies taking into account decision criteria such as vehicle’s autonomy, but also its cost and performance.System’s complexity is always increasing, so they require more and more precise simulations in order to better understand the phenomena involved - for example to study iron losses in an electric engine. 3D simulations provide very accurate results to study a body but are still not appropriate today for the study of large scale systems (ie. with many degrees of freedom, many optimization parameters and several areas of Physics). Indeed, 3D simulations computing time cost is directly linked with the number of degrees of freedom. That’s why, in recent years, model order reduction techniques stir developments because they guarantee a good compromise between the computation time and accuracy of results produced by these models.In this study, we are interested in techniques that can be used in an industrial context around two axes: - the study of thermal phenomena (in the power electronics modules) - the study of electromagnetic phenomena (in electric engines)
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Cesta na Hostýn / Path to the HostýnBulisová, Lenka January 2015 (has links)
Proposal to adjust the pedestrian paths in urban and forest parts. Urban solution of the complex in the sv. Hostýn. Creating multiple stop for rest and meditation.
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