Letteratura scientifica selezionata sul tema "RMN en flux"
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Articoli di riviste sul tema "RMN en flux"
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Perrillat-Mercerot, A., A. Miranville, C. Guillevin e R. Guillevin. "Modélisation mathématique des flux de glutamate intracérébraux intégrant les données RMN spectroscopiques". Journal of Neuroradiology 45, n. 2 (marzo 2018): 92. http://dx.doi.org/10.1016/j.neurad.2018.01.014.
Testo completo
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Beauvieux, M. C., P. Couzigou, H. Gin, V. Rigalleau e J. L. Gallis. "P175 Les flux unidirectionnels du métabolisme du glycogène du foie isolé sont inhibés par la perfusion d’éthanol 10 mM en présence d’insuline. Étude RMN chez le rat". Diabetes & Metabolism 34 (marzo 2008): H89. http://dx.doi.org/10.1016/s1262-3636(08)73087-8.
Testo completo
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Mhd Noor, Ervina Efzan, e Ayodeji Samson Ogundipe. "Effect of fluxes on Sn-Zn-Bi solder alloys on copper substrate". Soldering & Surface Mount Technology 29, n. 4 (4 settembre 2017): 225–34. http://dx.doi.org/10.1108/ssmt-05-2017-0014.
Testo completoAbstract (sommario):
Purpose This paper aims to investigate the effect different fluxes have on the mechanical properties of lead-free solders, specifically Sn-Zn-Bi solder alloy. The solder billets were soldered in between copper substrates and flux was applied. The mechanical tests carried out on the solder alloys were tensile and shear tests. They were experimented on with different fluxes, namely, water-soluble (paste), rosin mildly activated (RMA) and insoluble (RMA) flux. From these experiments, the ultimate tensile strength, shear strength, elongation, yield stress, Young’s modulus and the stress-strain curve are derived. The results showed that solder billets that were soldered onto copper substrates with water-soluble flux yielded the highest ultimate tensile strength and shear strength values of 9.9961 MPa and 118.836 MPa, respectively. Billets soldered using RMA flux had the highest values of elongation and Young’s modulus, 0.306 mm and 50,257.295 MPa, respectively. However, on viewing the failure of all the specimens under an optical microscope and scanning electron microscope (SEM), specimens soldered using water-soluble flux possessed the least deformities, depicting their higher level of mechanical properties, entailing their strength and ductility, deeming them as the most suitable flux for microelectronic applications. Design/methodology/approach The solder billets were soldered in between copper substrates and flux was applied. The mechanical tests carried out on the solder alloys were tensile and shear tests. They were experimented on with different fluxes, namely, water-soluble (paste), RMA and insoluble flux (RMA) flux. From these experiments, the ultimate tensile strength, shear strength, elongation, yield stress, Young’s modulus and the stress-strain curve are derived. Findings The results showed that solder billets that were soldered onto copper substrates with water-soluble flux yielded the highest ultimate tensile strength and shear strength values of 9.9961 MPa and 118.836 MPa, respectively. Originality/value This paper demonstrated that water-soluble fluxes gave the better strength and were most suitable for microelectronics applications.
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Ryabenko, L. G., V. S. Zelentsov, L. R. Ovcharova, G. G. Galkina, S. V. Sklyarov, S. V. Zelentsov e E. V. Moshnenko. "The oil flax variety RFN". Oil Crops 177, n. 1 (25 maggio 2019): 143–45. http://dx.doi.org/10.25230/2412-608x-2019-1-177-143-145.
Testo completo
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Travis, Mike. "RCN must flex its union muscles". Nursing Standard 30, n. 45 (6 luglio 2016): 30. http://dx.doi.org/10.7748/ns.30.45.30.s30.
Testo completo
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Vettier, Christian, e Anne Le Noel. "Le réacteur à haut flux et l'institut Laue-Langevin". Revue Générale Nucléaire, n. 6 (novembre 2000): 61–62. http://dx.doi.org/10.1051/rgn/20006061.
Testo completo
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Silva, Priscila de Souza, e Silvana Nunes de Queiroz. "Migração intraestadual no Rio Grande do Norte". Ideias 11 (1 maggio 2020): e020008. http://dx.doi.org/10.20396/ideias.v11i0.8658503.
Testo completoAbstract (sommario):
O principal objetivo deste trabalho é analisar a evolução recente da migração intraestadual no Rio Grande do Norte, a partir dos fluxos entre a Região Metropolitana de Natal (RMN) e o interior do estado, e o interior e a Região Metropolitana de Natal, durante os quinquênios de 1995/2000 e 2005/2010. Para tanto, a principal fonte de informações são as amostras dos microdados dos Censos Demográficos de 2000 e 2010 fornecidos pelo Instituto Brasileiro de Geografia e Estatística (IBGE). Os principais resultados mostram maior dinamização das migrações dentro do próprio estado e intensificação da tendência do fluxo metrópole-interior, com expressiva diminuição no saldo negativo do interior em relação à RMN. Em termos de municípios, o destaque foi Mossoró, que apresentou o maior volume de imigrantes e de emigrantes do e para a RMN, e maior redução no saldo migratório negativo, entre os interregnos de 1995/2000 e 2005/2010. Em contrapartida, na RMN houve declínio nos ganhos populacionais vindos do interior e significativo aumento das emigrações para a respectiva área, evidenciando a redução na capacidade de atração, notadamente da capital (Natal), que figura com maior saldo migratório positivo e volume de entradas e saídas, do e para o interior potiguar.Com isso, entre os interregnos em análise, Natal diminui expressivamente o saldo positivo, fruto de um conjunto de externalidades negativas que associadas a maior dinamização do interior, sobretudo, cidades médias, impulsionam a manutenção da população no interior, bem como a reemigração, desconcentrando a população da RMN.
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Hugrass, WN. "A General Physical Model for RMF Current Drive". Australian Journal of Physics 41, n. 6 (1988): 765. http://dx.doi.org/10.1071/ph880765.
Testo completoAbstract (sommario):
Rotating magnetic fields (RMF) have been used successfuly to drive steady currents in plasmas in many experiments. Some recent experimental and theoretical results did not seem to agree with the standard model based on assuming that the electrons are 'tied' to the lines of the RMF. A more general model based on the concept of flux preserving motion is developed in this paper. It appears that this model provides a unified approach for predicting the qualitative features of RMF current drive under a variety of conditions.
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Hanine, Ilyas. "La difficile équation économique de la chaleur nucléaire". Revue Générale Nucléaire, n. 3 (2024): 44–45. http://dx.doi.org/10.1051/rgn/20243044.
Testo completoAbstract (sommario):
Les modèles économiques dans le secteur de l’énergie jouent un rôle crucial dans la sécurisation des flux de revenus attendus par les financeurs. Or ces modèles évoluent et nécessitent une adaptation constante de tous les acteurs.
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Perthame, Benoît, Nicolas Vauchelet e Zhian Wang. "The flux limited Keller–Segel system; properties and derivation from kinetic equations". Revista Matemática Iberoamericana 36, n. 2 (25 novembre 2019): 357–86. http://dx.doi.org/10.4171/rmi/1132.
Testo completoTesi sul tema "RMN en flux"
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Higazi, Ahmed. "Contribution à l'étude des profils des vitesses des fluides dans les conduites par l'imagerie de flux RMN". Toulouse 3, 1993. http://www.theses.fr/1993TOU30032.
Testo completoAbstract (sommario):
Ce travail porte sur l'etude des profils de vitesse d'ecoulement des fluides (newtoniens, non-newtoniens) et le calcul de la contrainte de cisaillement a partir des profils de vitesse mesures par la resonance magnetique nucleaire (rmn) a l'echelle macroscopique et a l'echelle microscopique. Ce travail comporte deux volets, le premier volet concerne l'analyse theorique du phenomene de la rmn et les principes de l'imagerie de flux a deux echelles. Le deuxieme volet concerne l'analyse experimentale, il comporte trois series d'experiences effectuees sur un spectro-imageur de 2. 35 tesla, afin de mesurer les profils de vitesse d'ecoulement d'un fluide newtonien (eau), d'un fluide non-newtonien, et d'ecoulement sanguin (in-vivo). Les resultats de ces experiences montrent une bonne concordance avec ce qui est predit par la theorie
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WECKER, DIDIER. "Imagerie de flux par resonance magnetique nucleaire". Université Louis Pasteur (Strasbourg) (1971-2008), 1989. http://www.theses.fr/1989STR13070.
Testo completoAbstract (sommario):
Deux techniques sont presentees: les images a contraste de phase (reelles, imaginaires et de phase) qui permettent d'etudier les mouvements des parois cardiaques et l'angiographie irm obtenue par soustraction de deux images dans lesquelles les fluides en ecoulement donnent une intensite de signal differente. Trois methodes sont comparees. Une technique de "cine" irm basee sur la sequence echo de gradient ainsi que ses applications pour caracteriser les pathologies valvulaires est presentee
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Mahmoud, Mohamed. "Effets de modifications génétiques et environnementales sur le métabolisme de bactéries lactiques : étude quantitative de flux par SMRI et 2H-RMN en abondance naturelle". Nantes, 2004. http://www.theses.fr/2004NANT2013.
Testo completoAbstract (sommario):
L'influence des facteurs génétiques et environnementaux sur l'utilisation des substrats au cours de la fermentation par les bactéries lactiques a été étudiée par le biais des méthodes isotopiques quantitatives. L'étude a été menée sur trois plans. Dans la première partie, on a fait varier de façon systématique les concentrations en glucose et en citrate. Dans la deuxième partie, deux souches génétiquement manipulées, dont les gènes codant pour deux enzymes clés ont été successivement modifiés, ont été choisis comme modèle d'étude. Il a pu être établi, grâce aux études isotopiques menées par SMRI en abondance naturelle, que ces modifications engendrent de considérables changements du flux métabolique. Ces études ont également montré clairement le rôle clé du pyruvate dans le métabolisme énergétique des bactéries lactiques. Dans la troisième partie, les coefficients de transfert du deutérium entre les hydrogènes du glucose (substrat) et ceux de l'acide lactique (produit principal) ont été déterminés par RMN 2H-en abondance naturelle. Il a été démontré que ce transfert dépendait à la fois de la voie métabolique empruntée et du type génétiqueThe way in which genetic and environmental factors influence the utilisation of substrates during fermentation by lactic acid bacteria has been examined using quantitative isotopic techniques. Three approaches have been used. Firstly, the concentrations of citrate and glucose and their ratio were systematically varied. Secondly, a genetically manipulated model was studied in which two key genes were altered sequentially. These deletions cause a major shift in the metabolic flux. The associated changes in substrate partitioning were determined by IRMS at natural abundance. These studies clearly show the key role of pyruvate in the energy metabolism of lactic acid bacteria. In the third part, the transfer coefficients of deuterium between glucose as substrate and lactic acid as product were measured by NMR at natural abundance. It was shown that these depend both on the pathway being used to metabolise glucose and on the genetic composition of the bacterial strain used
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Beuste, Christophe. "Analyse modulaire in vivo du contrôle du flux énergétique dans le muscle squelettique de rat par spectroscopie RMN 31P : influence de l'hypoxie et de l'activité physique". Bordeaux 2, 2007. http://www.theses.fr/2007BOR21483.
Testo completoAbstract (sommario):
Nous étudions les propriétés cinétiques in vivo de l’énergétique dans le muscle squelettique actif. Le métabolisme énergétique est abordé comme un système de transfert d’énergie via des intermédiaires métaboliques : un système à deux modules (Producteur et Consommateur) connectés par un intermédiaire énergétique commun (PCr). L’analyse MoCA associée à la mesure de PCr par SRM 31P permet d’obtenir in vivo les coefficients d’élasticité et de contrôle pour une large gamme d’activité. Notre première étude montre un déplacement du contrôle sur le flux, de la demande vers la production, à mesure que l’activité contractile augmente; ce changement est principalement dû à un changement de sensibilité du Producteur vis-à-vis des intermédiaires énergétiques. L’analyse top-down d’élasticité est utilisée pour identifier les cibles de l’hypoxie chronique (6 semaines, 10,5%O2), de l’hypothyroïdisme et de l’activité physique chronique, décrits comme des stress pouvant modifier des réactions du Producteur et/ou du Consommateur. Les propriétés internes du système ne sont pas affectées par les changements de masse mitochondriale et/ou du type de fibres musculaires. La détermination expérimentale des propriétés internes du système permet de quantifier l’effet direct de l’hypoxie aiguë. Dans nos conditions, la principale adaptation du métabolisme énergétique à l’hypoxie chronique est une baisse de la sensibilité du Producteur vis-à-vis d’une diminution de l’O2 ambiant. La mise au point de notre approche permet d’étudier de manière intégrée le métabolisme énergétique du muscle squelettique et d’identifier les altérations fonctionnelles suite à des stimuli physiologiques ou pathologiquesWe attempted to describe quantitatively the main kinetic properties of energy metabolism of contracting skeletal muscles of rats in vivo. For that, energy metabolism was defined as a two-module system (supply-demand) connected by energetic intermediate (PCr as representative) assessed in vivo by 31P MRS; such a simplification allowed application of top-down (modular) control analysis to obtain elasticity and control coefficients over a broad spectrum of muscle activities. The main finding of our first study was the shift of control over the contraction from demand at low workloads to supply at high workloads. This was mainly due to the change in sensitivity of supply toward energetic intermediates. Top-down elasticity analysis was used to identify the targets (supply and/or demand) of hypoxic conditioning (6 weeks at 10. 5% O2), hypothyroïdism and chronic physical activity, described as stress generating muscle remodelling. No change in the elasticity of neither supply nor demand toward intermediates were observed: internal properties of the system were unaffected by reported changes in mitochondrial content and/or change in fibre type composition. Once internal properties experimentally obtained, the direct effect of acute hypoxia by measuring the contraction energy flux change was quantified. The main response of energy metabolism to chronic hypoxia was the decrease in sensitivity of supply toward acute decrease in ambient O2. As demonstrated by these applications, the design and set up of our experimental modular approach has the potential to detect a number of physiological effects on energy metabolism of skeletal muscle at a system level of integration
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Chaumeil, Myriam. "Mesure du métabolisme énérgétique cérébral par RMN du 31P in vivo : validation méthodologique multimodale et application à l'étude de la neurodégénérescence". Paris 11, 2008. http://www.theses.fr/2008PA112365.
Testo completoAbstract (sommario):
Au cours des dernières décennies, des techniques de neuroimagerie atraumatiques et non invasives visant à évaluer les flux métaboliques cérébraux ont été développées. Parmi elles, la spectroscopie par résonance magnétique (SRM) du 31P présente l'avantage de permettre la mesure directe du flux cérébral de synthèse d'ATP, mais apparaît encore à ce jour un défi méthodologique. Dans une première étude de neuroimagerie multimodale, la consommation régionale de glucose CMRglc, la vitesse du cycle de Krebs (Vtca) et la vitesse de synthèse d'ATP (Vatp) ont été mesurées dans le cerveau de primate sain respectivement par TEP (tomographie par émission de positrons) 18F-FDG, SRM du 13C et transfert de saturation par SRM du 31P. La cohérence de ces trois flux a permis de valider la méthode de transfert de saturation par SRM du 31P pour la mesure directe de Vatp cérébrale. L'intérêt de la SRM du 31P a ensuite été évalué sur des patients atteints de la maladie de Huntington (MH). Un maintien de l’homéostasie métabolique, une diminution non significative de Vatp, et une augmentation significative du pH ont été mis en évidence dans le cerveau de ces patients. L'alcalinisation cérébrale, pour la première fois mesurée dans la MH, présentait de plus une corrélation avec les scores cliniques moteurs. Au vu de ce résultat, une étude visant à évaluer la précocité des variations de pH associées à la MH a été réalisée sur un modèle rongeur au cours d'une intoxication chronique à l'acide 3-nitropropionique (3NP). Une augmentation significative du pH précédant l'apparition de lésions striatales a été mise en évidence, démontrant la potentialité du pH comme biomarqueur précoce de la MHNeuroimaging methods have considerably developed over the last decades and offer various non-invasive approaches for measuring cerebral metabolic fluxes. Among these methods, 31P magnetic resonance spectroscopy (MRS) has the particularity to directly measure cerebral ATP synthesis, but is still methodologically challenging. In this context, a multimodal neuroimaging study was performed in order to validate the saturation transfer 31P MRS method as a quantitative measurement of brain ATP synthesis. Glucose consumption (CMRglc), TCA cycle flux (Vtca ) and rate of ATP synthesis (Vatp) were measured in primate monkeys using 18F-FDG PET scan, indirect 13C MRS and saturation transfer 31P MRS, respectively. The consistency of these three fluxes with literature and, more interestingly, one with each other, demonstrated the robustness of saturation transfer 31 P MRS for directly evaluating ATP synthesis in the living brain. The potential of 31P MRS was then evaluated on Huntington's disease patients. Stability of metabolic homeostasis, non-significant decrease in Vatp, and significant increase in cerebral pH were shown in HD patient's brain. The increase in cerebral pH, detected for the first time in MH, was correlated with motor scores. Given these results, in order to assess the precocity of pH variations associated with MH, a study was performed on a rodent chronic model of MH. A significant increase in cerebral pH was detected before any lesions evidence, showing the potentiality of pH measurement as early biomarker of MH
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Boulais, Myrina. "Métabolisme énergétique du spermatozoïde d'huître creuse (Crassostrea gigas)". Thesis, Brest, 2014. http://www.theses.fr/2014BRES0116/document.
Testo completoAbstract (sommario):
Cette thèse présente une étude du métabolisme énergétique du spermatozoïde d’huître creuse, Crassostrea gigas. Les principaux objectifs sont (1) d’établir la dynamique des caractéristiques cellulaires et biochimiques du spermatozoïde de cette espèce durant la phase de mouvement, (2) d’identifier les voies de synthèse d’ATP et leurs substrats et (3) de déterminer l’implication du métabolisme énergétique dans le succès à la fécondation du spermatozoïde de cette espèce. Les résultats de ce travail montrent la longue durée du mouvement (de 24 à 72h) du spermatozoïde d’huître creuse et le maintien d’une concentration élevée en ATP intracellulaire, jusqu'à la fin du mouvement. Le rôle de la phosphorylation oxydative (OXPHOS) dans la synthèse d’ATP a été mis en évidence. Le spermatozoïde d’huître creuse montre une grande plasticité dans l’utilisation de ses voies de production d’énergie, assurant la synthèse d’ATP par d’autres voies qu’OXPHOS lorsque la mitochondrie est inhibée. L’accumulation de phosphoarginine en fin de mouvement montre une capacité de stockage de l’ATP synthétisé. La nature des substrats endogènes utilisés pour la synthèse d’ATP reste cependant à déterminer. La forte capacité de régulation du métabolisme énergétique du spermatozoïde d’huître creuse, associée à la possibilité de synthétiser de l’énergie au cours de sa longue phase de nage, contribuent probablement au succès du peuplement observé chez cette espèce. Ce travail apporte une première description du métabolisme énergétique du spermatozoïde d’huître creuse, améliorant la connaissance fine de cette celluleThe present study aims at describing the energy metabolism of Pacific oyster, Crassostrea gigas, spermatozoon. The main objectives are: (1) describing the kinetic of cellular and biochemical characteristics of Pacific oyster spermatozoon during its movement phase, (2) identifying the metabolic pathways to produce energy and their substrates, (3) determining the involvement of energy metabolism in fertilization success. The results showed the long duration (ranging 24 to 72h) of the movement of Pacific oyster spermatozoon and the maintenance of a high intracellular ATP content until the end of the movement phase. The role of oxidative phosphorylation (OXPHOS) in ATP production was highlighted. Alternative ATP producing pathways might contribute to sustain energy production when OXPHOS is impaired, showing the high adaptation capacity of Pacific oyster spermatozoa. An increase of phosphoarginine content observed at the end of the movement phase suggests energy storage capacity. Endogenous substrates involved in ATP synthesis must be determined. Both the high regulation capacity of the energy metabolism of Pacific oyster spermatozoa and their ability to restore energy stores catabolized during movement likely contribute to the successful settlement observed in the wild. In conclusion, this work provided a fine description of energetic metabolism of Pacific oyster spermatozoon
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ROTH, MURIEL. "Développements méthodologiques en imagerie d'activation cérébrale chez l'homme par résonance magnétique nucléaire : quantification de flux, imagerie de l'effet BOLD et correction des mouvements de la tête". Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10016.
Testo completoAbstract (sommario):
Ce travail est centre sur les developpements methodologiques en imagerie par resonance magnetique des fonctions du cerveau. Une nouvelle methode d'irm fonctionnelle quantitative basee sur la mesure du debit sanguin est tout d'abord decrite. Des images angiographiques ont permis de mesurer le debit dans une veine drainant le cortex moteur. Des variations significatives du debit sanguin entre des periodes de repos, de simulation mentale et d'execution d'un acte moteur ont ete mises en evidence. Ces informations fonctionnelles ne permettent pas de localiser precisement les regions corticales activees. Cette localisation a ete effectuee en appliquant un traitement approprie sur des images sensibles aux variations du taux d'oxygenation sanguine. Des cartes d'activation cerebrale de bonne resolution spatiale ( 3 mm) sont ainsi obtenues. Nous avons alors demontre que l'aire motrice primaire est activee lors de la simulation mentale d'un acte moteur. Les mouvements de la tete survenant pendant un examen fonctionnel induisent des erreurs sur les cartes d'activation. Un nouvel algorithme de correction des deplacements dans le plan des images est presente. Cet algorithme utilise les proprietes de la transformation de fourier concernant les rotations et les translations afin de determiner rapidement les parametres du deplacement. Des tests sur des images simulees ont permis de montrer la fiabilite et la precision de l'algorithme.
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Netto, Antonio Marchi. "Análise da influência dos parâmetros espectrais da RMN-CWFP em medidas quantitativas em fluxo". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-18092009-090420/.
Testo completoAbstract (sommario):
A seqüência de pulsos RMN-CWFP (Ressonância Magnética Nuclear - Precessão Livre de Onda Contínua) tem encontrado diversas aplicações na ciência. O presente trabalho analisa a grande sensibilidade dessa seqüência em relação a variações de seus parâmetros espectrais, exclusivamente em uma caracterização teórico-experimental da RMN-CWFP em fluxos do tipo plug-flow, exemplificados por medidas online através do transporte de sementes por uma esteira sob um campo magnético constante no tempo. Foram feitas simulações e medições em várias condições, variando os fatores que influenciam as medidas, como ângulo de nutação (?), ângulo de offset (?), tempo entre pulsos (Tp), gradiente (G), velocidade (v) e tempos de relaxação longitudinal (T1) e transversal (T2). Em determinadas condições fixas de ângulo de nutação, precessão, tempo entre pulsos, gradiente e velocidade, foi observado que poderia existir um ponto nulo com dependência entre T1 e T2. Esse fenômeno foi estudado e algumas aplicações foram sugeridas. O trabalho também validou a seqüência de pulsos CWFP em fluxo como ferramenta para análises quantitativas da massa de óleo em sementes.The NMR-CWFP pulse sequence (Nuclear Magnetic Resonance - Continuous Wave Free Precession) has met several applications in the science. The present work analyses the high sensibility of this sequence to its spectral parameters variation, exclusively in a theoretical and experimental characterization of the flow NMR-CWFP of the kind plug-flow, exemplified by online measures by seeds transport through a mat under a magnetic field constant in time. Simulations and measurements were made on several conditions, varying the factors that have measurement influence, like flip angle (??, offset angle (??, time between pulses (Tp), gradient (G), velocity (v) and longitudinal and transversal relaxation times (T1 and T2). Under certain conditions of flip angle, precession, time between pulses, gradient and velocity, it was noticed that there might be a null point with T1 and T2 dependence. This phenomenon was studied and some applications have been suggested. The work has also validated the CWFP pulse sequence as a quantitative tool to quantitative analysis of seeds oil mass.
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Ridel, Mélissa. "Reconstruction du flux d'énergie et recherche de squarks et gluinos dans l'expérience DØ". Paris 11, 2002. http://www.theses.fr/2002PA112101.
Testo completoAbstract (sommario):
DØ est l'une des 2 expériences du collisionneur pp ̃du Fermi National Accelerator Laboratory près de Chicago. Après 5 années d'arrêt, le Run II a débuté en mars 2001. Il permettra d'explorer de nouveaux domaines de masses de squarks et de gluinos, particules supersymétriques dont la signature en jets et énergie tranverse manquante est l'objet de ce travail. Mais, avant le démarrage, j'ai travaillé sur des améliorations hardware et software de la mesure de l'énergie, essentielle pour les jets et l'énergie transverse manquante. Une simulation des chaînes de lecture et de calibration de chaque voie du calorimètre a été réalisée. Son résultat dépend de 8 grandeurs caractéristiques qui ont été extraites par traitement du signal de mesures de réflectométrie temporelle. Elle permettra de définir une stratégie de calibration du calorimètre. Une clusterisation des dépôts d'énergie calorimétrique a été réalisée (cellNN) basée sur la cellule et non la tour et exploitant au maximum la granularité du calorimètre notamment en débutant dans le 3ème compartiment électromagnétique, 4 fois plus granulaire que les autres. L'information longitudinale permet de séparer les particules électromagnétiques et hadroniques superposées. Ainsi, tous les éléments indispensables à la reconstruction individuelle des gerbes sont mis en œuvre. Puis, l'energy flow combine les clusters cellNN et les traces reconstruites dans la cavité centrale pour conserver la meilleure mesure de l'énergie et améliorer ainsi la reconstruction du flux d'énergie de chaque événement. L'efficacité des déclenchements calorimétriques actuels a été déterminée et utilisée pour une recherche de squarks et gluinos utilisant des événements Monte Carlo dans le cadre de mSUGRA. Une limite inférieure sur les masses des squarks et des gluinos qu'atteindra DØ avec 100 pb^(-1) de luminosité est prédite à partir d'outils de reconstruction standard; elle pourra être améliorée grâce à l'utilisation de l'energy flowThe DØ experiment is located at the Fermi National Accelerator Laboratory on the TeVatron proton-antiproton collider. The Run II has started in march 2001 after 5 years of shutdown and will allow DØ extend its reach in squarks and gluinos searches, particles predicted by supersymmetry. In this work, I focussed on their decays that lead to signature with jets and missing transverse energy. But before the data taking started, I studied bath software and hardware ways to improve the energy measurement which is crutial for jets and for missing transverse energy. For each calorimeter channel, the physics and the calibration signal has been simulated based on a database of the 8 parameters that describe each channel. The parameters have been extracted from time reflectometry measurements. The calibration strategy can be defined using this simulation. Energy deposits in the calorimeter has been clustered with celINN, at the cellievei instead of the tower level. Efforts have been made to take advantage of the calorimeter granularity to aim at individual particles showers reconstruction. CellNN starts from the third floor which has a quadruple granulariry compared to the other floors. The longitudinal information has been used to detect electromagnetic and hadronic showers overlaps. Then, clusters and reconstructed tracks from the central detectors are combined and their energies compared. The better measurement is kept. Using this procedure allows to improve the reconstruction of each event energy flow. The efficiency of the current calorimeter triggers has been determined. They has been used to perform a Monte Carlo search analysis of squarks and gluinos in the mSUGRA framework. The lower bound that DO will be able to put on squarks and gluinos masses with a 100 pb^(-1) integrated luminosity has been predicted. The use of the energy flow instead of standard reconstruction tools will be able to improve this lower limit
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Mayaffre, Hadrien. "Etude d'un supraconducteur organique bidimensionnel par resonance magnetique nucleaire". Paris 11, 1996. http://www.theses.fr/1996PA112115.
Testo completoAbstract (sommario):
Ce travail porte sur le compose kappa-(et)2cun(cn)2br, supraconducteur organique a caractere bidimensionnel. La technique d'investigation utilisee est la resonance magnetique nucleaire (rmn). Les mesures ont ete menees sur deux types de noyaux, les protons et les carbones du centre de la molecule et. Ceci nous a permis d'avoir acces a des informations tres complementaires sur le systeme. Les conclusions essentielles de cette these sont les suivantes. La phase metallique ne peut pas etre decrite comme un liquide de fermi traditionnel. La rmn revele l'existence de fortes correlations antiferromagnetiques bien au-dessus de la transition supraconductrice qui sont sans doute les vestiges d'une phase antiferromagnetique. L'application d'une pression hydrostatique tend a ramener le systeme vers un comportement plus normal. Les proprietes de la phase mixte de l'etat supraconducteur sont tres anisotropes. En champ perpendiculaire, la contribution des curs de vortex domine la relaxation nucleaire du carbone qui depend donc fortement du champ. En champ parallele au contraire, les lignes de flux sont bloquees et cette contribution disparait. En revanche, sur le proton la relaxation est dominee par les effets lies aux mouvements des lignes de flux. Les excitations de basse energie revelees par la relaxation nucleaire du carbone montrent que le gap supraconducteur presente des lignes de zeros au niveau de fermi ou est tout au moins fortement anisotrope
Libri sul tema "RMN en flux"
1
Huiqi, Chen, a cura di. Tou nao hao de ren dou he ya ma ren you: Chan sheng jue jia xiao guo de yin shi shu = Flax seed oil. Taizhong Shi: Chen xing chu ban you xian gong si, 2012.
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2
1945-, Gerba Charles P., Ning Bo e Zhang Hongbin, a cura di. Bie chuan ran wo!: Xian dai sheng huo gong gong wei sheng shou ce = The germ freak's guide to outwitting colds and flu. Beijing: Dang dai Zhongguo chu ban she, 2006.
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3
Wright, A. G. Measurement of low light flux. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199565092.003.0007.
Testo completoAbstract (sommario):
There are three experimental methods for quantifying the flux of light incident on a photocathode: counting the anode output pulses initiated by photoelectrons—known as photon counting; measuring the DC current flowing at the anode—referred to as analogue detection, or charge integration; and determining the rms noise in the anode current—known as shot noise power detection. The statistical performances of the three methods, based on weighting factors, are compared, revealing the theoretical superiority of the photon-counting method. Optimal time allocation between signal and background measurement is derived for photon counting. An amplifier discriminator is the simplest and preferred instrumentation for photon counting, but setting the optimal counting threshold is ultimately a matter of judgement. This is because the plateau has a different slope for signal, background, and afterpulses. Rudiments of signal recovery instrumentation covering boxcar integrators, lock-in detection, and synchronous signal averaging are given.
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Hart-Brinson, Peter. The Gay Marriage Generation. NYU Press, 2018. http://dx.doi.org/10.18574/nyu/9781479800513.001.0001.
Testo completoAbstract (sommario):
The rapid increase in public support for gay marriage in the United States between 1988 and 2015 is unprecedented in modern polling. How and why did an idea that was once nonsense become a political reality supported by a majority of the population in such a short period of time? This book analyzes historical data, public opinion data, and qualitative interview data to explain the role of generational change in causing the legalization of gay marriage. Despite the evidence of generational change we see all around us, social scientists have struggled to document and explain generational change thoroughly; this has allowed myths and stereotypes about generations to run amok in popular culture. This book corrects this shortcoming and explains America’s cultural revolution in attitudes about gay marriage. It argues that the rapid shift in public support for gay marriage was caused by a change in the social imagination of homosexuality. Americans coming of age during different historical periods developed understandings of homosexuality that were consistent with the cultural common sense of the era, thus making them more or less likely to support gay marriage. The story of gay marriage’s rapid ascent offers profound insights about how the continuous remaking of the population through birth and death, mixed with our shared history and culture and our individual life experiences, produces a society that is continually in flux and constantly reinventing itself anew.
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Guarneri, Michael. Vampires in Italian Cinema, 1956-1975. Edinburgh University Press, 2020. http://dx.doi.org/10.3366/edinburgh/9781474458115.001.0001.
Testo completoAbstract (sommario):
The book takes as its subject a corpus of thirty-three vampire movies made, distributed and exhibited during the peak years of film production in Italy, and certified to be of Italian nationality by state institutions such as the Italian Show Business Bureau and the Italian Film Censorship Office. Positioning itself at the intersection of Italian film history, horror studies and cultural studies, the book asks: why, and how, is the protean, transnational and transmedial figure of the vampire appropriated by Italian cinema practitioners between 1956 and 1975? Or, more concisely, what do the vampires of post-war Italian cinema mean? The aim is to show that – in spite of Italian vampire cinema’s imported and derivative nature, and its great reliance on profits coming from distribution on the international market – Italian cinematic vampires reflect their national zeitgeist from the economic miracle of the late 1950s to the mid-1970s austerity, twenty years of large political and socio-economic change in which gender politics were also in relative flux. The result of an original research into film production data, film censorship files, screenplays, trade papers, film magazines and vampire-themed paraliterature, the book leaves the well-trod track of award-winning art films to shed light on some of the so-called ‘lower forms’ of cinematic culture, looking for the economic backbone and cultural instrumentality of post-war Italian cinema in the run-of-the-mill genre movies rushed through a cheap production and into domestic and international distribution to parasitically (vampirically?) exploit a given commercially successful film.
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Castro, Miranda. Complete Homeopathy Handbook: Safe and Effective Ways to Treat Fevers, Coughs, Colds and Sore Throats, Childhood Ailments, Food Poisoning, Flu, and a Wide Ran. Echo Point Books & Media, LLC., 1991.
Cerca il testo completoCapitoli di libri sul tema "RMN en flux"
1
Levine, Alison J. Murray. "Depth of Field". In France in Flux, 63–91. Liverpool University Press, 2019. http://dx.doi.org/10.3828/liverpool/9781786941787.003.0004.
Testo completoAbstract (sommario):
This chapter investigates the field of contemporary French documentary as a source for cultural representations of farmland and farm life, a segment of the national territory that has undergone profound change in the past half-century. Farmland, which represents over half of the surface area of metropolitan France, provides employment to an ever-smaller percentage of the population. The amount of land needed to make a living continues to grow, and farms are increasingly run by corporations rather than by people who live and work on the same property. Since 2000, a significant number of French documentaries have explored to the changes wrought to the landscape and to farm life by the agricultural industrialisation of the previous half-century. By reading across a broad collection of recent documentaries on farming, this chapter reveals the contours of a broader conversation about the emergence of, and need for, new forms of reconnection between the inhabitants of rural and urban France. The contours of this conversation emerge both in the documentary forms and practices in the films as well as new forms of interaction between films and their audiences.
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Wildman, Steven S., e Han Ei Chew. "Television in Flux". In Understanding the Interactive Digital Media Marketplace, 378–91. IGI Global, 2012. http://dx.doi.org/10.4018/978-1-61350-147-4.ch030.
Testo completoAbstract (sommario):
The television landscape is in a state of flux. In this new environment, profit-driven media companies have to balance tradeoffs between traditional and new channels of video distribution to optimize returns on their investments in content generation. This chapter describes the challenges traditional television service providers face in adapting their strategies to an environment in which the internet is playing an increasingly prominent role as a new distribution channel. In the short to intermediate run there is the challenge of finding ways to monetize an internet audience without cannibalizing profits earned through traditional distribution channels. The longer-term challenge is adapting to a distribution technology that embeds a fundamentally different economic logic for video market organization. In this chapter, we describe and analyze current trends in the internet television market and traditional television industry players’ efforts to respond to the opportunities and threats posed by internet distribution.
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Bilston, Sarah. "Plotting the Suburbs". In The Promise of the Suburbs, 53–73. Yale University Press, 2019. http://dx.doi.org/10.12987/yale/9780300179330.003.0004.
Testo completoAbstract (sommario):
Novels set in suburban locales represent a world in flux. Beneath the shifting sands of social mobility run thick strands of apparently common knowledge that reassure readers of continuity with the past and the existence of enduring values. These values—such as suspicion of suburban homes’ commodity status, the charge of vulgar furnishing—undoubtedly express suspicion of the new masses. But they also form a means of fostering connections, shared perspectives, in a time of dizzying change.
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O’Shaughnessy, C. L., e 0. Durosinmi-Etti. "The use of hydraulic mechanisms for the development of high flux crossflow microfiltration systems". In European Brewery Convention, 681–90. Oxford University PressOxford, 1997. http://dx.doi.org/10.1093/oso/9780199636907.003.0081.
Testo completoAbstract (sommario):
Abstract The main reasons that crossflow microfiltra!ion has not been widely accepted in brewing is due to low filtrate productivity and potential loss of quality components. Studies aimed at understanding the fouling mechanisms involved have shown that filtration performance is influenced by raw materials, distribution of particulates within the beer and the filter membrane material. Three novel techniques for enhancing filtrate productivity without loss of beer components have been demonstrated, warmer filtration, pressure ramping (gradually increasing the pressure during a filter run) and backpulsing (the momentary reversal of filtrate flow to dislodge the fouling layer). The latter is the most effective.
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Eaglin, Jennifer. "Proálcool Reimagined, 1985–2003". In Sweet Fuel, 149—C6.F3. Oxford University PressNew York, 2022. http://dx.doi.org/10.1093/oso/9780197510681.003.0007.
Testo completoAbstract (sommario):
Abstract This chapter follows the story of the ethanol program from its rapid collapse in the late 1980s to its resurgence with the launch of the flex-fuel car in 2003. Drought and political mismanagement caused ethanol shortages that encouraged public debate about Proálcool’s long-term viability by 1990. In turn, the new democratic government removed support for the fuel replacement program but continued support for the fuel supplement program under Proálcool II. Propaganda for the revised program focused more on ethanol production’s environmental benefits, the alternative fuel’s contribution to reducing air pollution in large city centers, and the electricity grid. This new focus allowed the industry to successfully transition to a fully privatized industry by the end of the century. The 2003 launch of the new flex-fuel car which could run on any combination of ethanol and gasoline heralded a new beginning for the privatized industry in the twenty-first century.
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Shipton, Alyn. "Teddy Hill and Edgar Hayes". In Groovin’ High, 33–49. Oxford University PressNew York, NY, 1999. http://dx.doi.org/10.1093/oso/9780195091328.003.0003.
Testo completoAbstract (sommario):
Abstract In his autobiography, Dizzy lists the after hours joints where he was one of a coterie of sitters-in, despite the attempts of the American Federation of Musicians to discourage jam sessions. The union disliked club owners who paid a trio and, by encouraging guests, ended up appearing to present a full band, but Dizzy and his fellow trumpeters Charlie Shavers and Barna Warwick took every chance to flex their musical muscles, and ran rings round the union officials who checked up on clubs like George’s, the Yeah Man, the Victoria, the 101 Ranch, and Clark Monroe’s Uptown House.
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Kizza, Joseph M., e Li Yang. "Is the Cloud the Future of Computing?" In Cloud Technology, 2149–64. IGI Global, 2015. http://dx.doi.org/10.4018/978-1-4666-6539-2.ch102.
Testo completoAbstract (sommario):
Cloud computing as a technology is difficult to define because it is evolving without a clear start point and no clear prediction of its future course. Even though this is the case, one can say that it is a continuous evolution of a computer network technology. It extends client-server technology that offers scalability, better utilization of hardware, on-demand applications and storage, and lower costs over the long run. It is done through the creation of virtual servers cloned from existing instances. The cloud technology seems to be in flux; hence, it may be one of the foundations of the next generation of computing. A grid of a few cloud infrastructures may provide computing for millions of users. Cloud computing technology consists of and rests on a number of sound, fundamental, and proven technologies. This includes virtualization, service-oriented architectures, distributed computing, and grid computing. Based on these fundamental and sound computing principles, one wonders whether cloud computing is the next trajectory of computing. This chapter discusses this in depth and also looks at the security issues involved.
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Kizza, Joseph M., e Li Yang. "Is the Cloud the Future of Computing?" In Advances in Business Information Systems and Analytics, 57–72. IGI Global, 2014. http://dx.doi.org/10.4018/978-1-4666-5788-5.ch003.
Testo completoAbstract (sommario):
Cloud computing as a technology is difficult to define because it is evolving without a clear start point and no clear prediction of its future course. Even though this is the case, one can say that it is a continuous evolution of a computer network technology. It extends client-server technology that offers scalability, better utilization of hardware, on-demand applications and storage, and lower costs over the long run. It is done through the creation of virtual servers cloned from existing instances. The cloud technology seems to be in flux; hence, it may be one of the foundations of the next generation of computing. A grid of a few cloud infrastructures may provide computing for millions of users. Cloud computing technology consists of and rests on a number of sound, fundamental, and proven technologies. This includes virtualization, service-oriented architectures, distributed computing, and grid computing. Based on these fundamental and sound computing principles, one wonders whether cloud computing is the next trajectory of computing. This chapter discusses this in depth and also looks at the security issues involved.
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Vilela Junio, Juscelino Francisco, Juceluce da Silva Vilela e José Davi Ferreira Lopes. "PÓS-COVID-19: TREINAMENTO COM RESTRIÇÃO DE FLUXO SANGUÍNEO COMO ALIADO NO PROCESSO DE REABILITAÇÃO". In Ciências da Saúde: desafios e potencialidades em pesquisa - Volume 2, 383–93. Editora Científica Digital, 2022. http://dx.doi.org/10.37885/230211979.
Testo completoAbstract (sommario):
Objetivo: Analisar a literatura sobre o uso do método de restrição de fluxo sanguíneo e seu uso na reabilitação em indivíduos pós Covid-19. Métodos: Trata-se de uma revisão da literatura, onde foi realizada buscas nas bases de dados eletrônicas: Pubmed, Scielo,LILACS e Bireme, no período de janeiro 2023; os critérios de inclusão foram publicação entre o período de 2020 a 2023, que abordassem reabilitação de indivíduos que tiveram Covid-19 e treinamento com restrição de fluxo sanguíneo, já os critérios de exclusão foram artigos que envolvessem populações distintas ou estudos não disponíveis na integra. A seleção dos artigos foi desempenhada por dois revisores, que utilizaram as palavras-chave: Rehabilitation; strength training; restriction of blood flow; Covid-19; Kaatsu training. em combinações específicas com os buscadores boleanos “AND” e “OR”. Discussão: O Colégio Americano de Medicina Esportiva preconiza uma carga de 70 a 85% de 1 RM como uma carga ideal para modificar as variáveis musculares(força e hipertofia), porém na reabilitação de grupos especiais como o indivíduos pós covid 19, torna essa metodologia incapaz de ser utilizado na reabilitação, como contra medida a esse contexto o método Kaatsu training utiliza baixas carga de 1RM associado a restrição do fluxo sanguíneo para obter resultados na reabilitação similares a treinamentos de alta intensidades. Conclusão: essa metodologia de tratamento quando utilizada em indivíduos pós covid 19, pode ser uma alternativa favorável para aumento de força e melhora da funcionalidade.
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Vas, Peter. "Steady-State and Transient Operation Of Synchronous Machines and Synchronous Motor Drives". In Electrical Machines and Drives, 662–740. Oxford University PressOxford, 1993. http://dx.doi.org/10.1093/oso/9780198593782.003.0004.
Testo completoAbstract (sommario):
Abstract In the normal configuration, a three-phase synchronous machine has a symmetrical three-phase winding on its stator, which is sometimes also referred to as the armature winding, and it is similar to the stator winding of a three-phase induction machine. Its rotor can be either cylindrical or it can have salient poles, as shown in Fig. 2.25. As discussed in Section 2.7.6.2, on the rotor their is a field winding which is excited by d.c., and it is connected to the external d.c. source via slip rings and brushes. Sometimes there are no brushes, but there is brushless excitation by (rotating) diodes. Further-more, sometimes there are also damper windings on the rotor, the roles of which have been described in Section 2.7.6.2. Steam turbine driven synchronous machines (turbogenerators) run at high speeds (they have 2–4 poles) and are equipped with cylindrical rotors, since this construction is mechanically more reliable (it withstands the centrifugal forces at high speeds) than a salient-pole construction. However, water-driven generators (hydrogenerators) and also smaller independent generators (for example, used in emergency power supplies), run at relatively low speeds (a few hundred revolutions per minute) and they are constructed with salient poles (since this requires a larger number of poles; see eqn (4.1-1)). It should be noted that it is possible to construct a three-phase synchronous machine where the d.c. excitation winding is on the stator and the three-phase winding, supplied by a.c. is on the rotor, (inverted machine). However, this would require an increased number of slip rings and the currents through the slip rings would be large. It is an advantage of the application of the wound-rotor machine that the excitation flux can be varied to operate the synchronous machine with any desired value of power factor, which can be lagging, unity, or leading.
Atti di convegni sul tema "RMN en flux"
1
Li, Wanlin, Kan Wang, Ganglin Yu e Yaodong Li. "Research on Coupling Scheme of Monte Carlo Burnup Calculation in RMC". In 2018 26th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icone26-81140.
Testo completoAbstract (sommario):
Monte Carlo (MC) burnup calculation method, implemented through coupling neutron transport and point depletion solvers, is widely used in design and analysis of nuclear reactor. Burnup calculation is generally solved by dividing reactor lifetime into steps and modeling geometry into numbers of burnup areas where neutron flux and one group effective cross sections are treated as constant during each burnup step. Such constant approximation for neutron flux and effective cross section will lead to obvious error unless using fairly short step. To yield accuracy and efficiency improvement, coupling schemes have been researched in series of MC codes. In this study, four coupling schemes, beginning of step approximation, predictor-corrector methods by correcting nuclide density and flux-cross section as well as high order predictor-corrector with sub-step method were researched and implemented in RMC. Verification and comparison were performed by adopting assembly problem from VERA international benchmark. Results illustrate that high order coupled with sub-step method is with notable accuracy compared to beginning of step approximation and traditional predictor-corrector, especially for calculation in which step length is fairly long.
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Rule, Toby D., e Jungho Kim. "Wall Heat Transfer Measurements in Saturated Pool Boiling of FC-72 on a Small Heated Area". In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0794.
Testo completoAbstract (sommario):
Abstract Local wall heat flux measurements of saturated pool boiling of FC-72 on a small heated area held at constant wall temperature were made. An array of 96 temperature controlled heaters was used to measure the heat flux distribution on this surface. Array-averaged heat flux, RMS variations in heat flux, and local heat flux information is presented. Local heat flux variations are shown to be three to six times larger than variations in the spatially averaged heat flux.
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Agrawal, Smita, Terrence Simon, Mark North e Tianhong Cui. "Unsteady Heat Flux Measurements in Agitated Channel Flows". In ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ipack2015-48753.
Testo completoAbstract (sommario):
In this experiment, agitation is used in a rectangular channel for convective heat transfer enhancement. The channel under study is representative of a flow channel in an electronics cooling finned heat sink module. It is open at one end and has a translationally oscillating plate within it that agitates the flow. Contrary to the heat sink cooling channel, the test channel has no net through-flow so that agitation, isolated from throughflow effects, is studied. The channel is divided into three regions. The entry region is close to the open end of the channel. This would be near the fin tips in the finned heat exchanger channel. The base region is close to the other end of the channel where the flow makes an abrupt U-bend around the agitator plate. This is near the fin base region of a finned channel of a heat sink heat exchanger. The central region is between the two. Each region has special flow and convective heat transfer features for study. Ensemble-averaged velocities and RMS fluctuations of velocity are measured over the cycle. Measured data lend insight into the mixing phenomena in each region over the oscillation cycle. Unsteady heat flux measurements were made in each region and over the cycle to help in understanding the mechanisms affecting heat transfer. The unsteady heat flux characteristics in the entry and base regions seem to be more influenced by the RMS fluctuations of velocity, indicating that heat transfer in these regions is governed by turbulence generated by agitation. The unsteady heat flux trends in the central region seem to be more influenced by acceleration/deceleration of the flow than by turbulence-like structures.
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Rao, Junjie, Xiaotong Shang e Kan Wang. "Verification of Shielding Calculation Capability of RMC With H.B.Robinson-2 Pressure Vessel Benchmark". In 2018 26th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icone26-81694.
Testo completoAbstract (sommario):
RMC is a 3-D continuous energy Monte Carlo code developed by REAL team in Tsinghua University, China. Besides the capability of fuel cycle burnup calculation, hybrid MPI/OpenMP parallelism strategy, sensitivity and uncertainty analysis, N-TH coupling calculation, shielding calculation methods including general source description, regional importance method, weight window method and source biasing method have been also developed for deep penetration problems. H.B.Robinson-2 Pressure Vessel Benchmark (HBR-2 benchmark) is used for the qualification of pressure vessel neutron flux calculation methods and shielding calculations based on this model have been performed by Monte Carlo codes such as SCALE, MCNPX and deterministic transport code DORT. In this work, the verification calculation of shielding calculation capability of RMC is conducted based on HBR-2 benchmark. The total calculation consists of two stages. Criticality calculation is performed first to obtain the fission neutron distribution in the reactor core assemblies. Then the fission neutron distribution is regarded as the initial neutron source in the following fixed source calculation. Variance reduction techniques such as source biasing and regional importance methods are combined together to be able to reduce the variance of the neutron flux in regions within and outside the pressure vessel including the downcomer and cavity regions. The preliminary calculation results show good agreement with MCNP and the shielding calculation of RMC is justified and applicable for deep penetration problems.
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Woll, Alex, Guanlan Liu e Zhuoran Zhang. "Risk Modeling for Rupture Mitigation Valve". In 2024 15th International Pipeline Conference. American Society of Mechanical Engineers, 2024. https://doi.org/10.1115/ipc2024-129992.
Testo completoAbstract (sommario):
Abstract Per PHMSAs recent additions to 192.935 (c), if an operator determines that a Rupture Mitigation Valve (RMV) would be an efficient means of adding protection to their High Consequence Areas (HCAs) then they must install them. In order to determine if an RMV would be an efficient means of adding HCA protection, a risk analysis approach must be devised which considers the impacts of installing additional RMVs. RMV installation can improve both failure response time and valve spacing, both of which have an impact on the total time that a rupture with ignition can be sustained. PHMSAs definition of Potential Impact Radius (PIR) in 192.903 is associated with a sustained heat flux for a thirty second timeframe which results in a one percent likelihood of mortality. Because the PHMSA defined PIR has a fixed timeframe of concern and an RMV installation can impact the time that a rupture with ignition is maintained, in order to assess the impacts of an RMV, we cannot rely upon PHMSA PIR definition for this analysis. Instead, a correlation between heat flux over time (heat dosage) and distance with the likelihood of mortality and building ignition need be established to assess the impacts of RMV installation on reducing consequences associated with a sustained rupture with ignition. In developing that correlation, an operator can then evaluate if the installation of an RMV would be an efficient means of protecting their HCAs. An RMV risk modeling tool was developed to help operators minimize the consequences of a pipeline incident surrounding their HCAs. This presentation will cover the flow modeling approach, heat flux calculations, approximation of the transient state, and consequence modeling included in our RMV approach. This model supports operators in selecting optimal RMV spacing and locations surrounding their HCAs to most effectively protect public safety.
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Ratts, Eric B., e J. Steven Brown. "Laminar Entropy Generation Over a Flat Plate With Isothermal and Constant Heat Flux Boundary Conditions Using the Von Ka´rma´n Integral Method". In ASME 2004 Heat Transfer/Fluids Engineering Summer Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ht-fed2004-56088.
Testo completoAbstract (sommario):
This paper is a fundamental study on the irreversibility of single-phase laminar convective heat transfer over a flat plate with isothermal and constant heat flux boundary conditions. It quantifies the losses due to viscous momentum transfer losses and heat transfer losses and presents the irreversibility of the convective flow based on the entropy generation (EG) method. This paper determines the entropy generation for incompressible, single phase, laminar flow for large and small Prandtl numbers over a flat plate with isothermal and constant heat flux boundary conditions using von Ka´rma´n’s integral theory.
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Holmberg, D. G., T. Reid, T. Kiss, H. L. Moses, W. F. Ng e T. E. Diller. "Effects of Shock Wave Passage on Heat Transfer in a Transonic Turbine Cascade". In ASME 1994 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1994. http://dx.doi.org/10.1115/94-gt-179.
Testo completoAbstract (sommario):
Results from a new facility for measuring heat transfer in transonic turbine cascades are repotted. An air heater has been built into the blow-down wind tunnel to heat the main flow for a 20 second run time. This allows control of the direction and magnitude of the heat transfer into the blade throughout the tests. A Heat Flux Microsensor was inserted into the blade to measure simultaneous surface heat flux and temperature. Measurements were made on the suction surface of the blades toward the trailing edge. Because of the long run times (20 s), the adiabatic wall temperature could be determined directly from the measured surface temperature and heat flux. Simultaneous pressure measurements were made with a Kulite transducer at the same distance from the leading edge to document shock passage. A separate shock tube was used to generate a shock wave which was introduced into the test section in front of the cascade. This shock was carried over the blade by the main flow. The resulting changes in heat flux correlated strongly with the unsteady pressure changes. An overall increase of 1.5 W/cm2 in heat flux was recorded for a pressure increase of 7 kPa during the initial passage of the shock.
8
Hradisky, Michal, e Thomas Hauser. "Evaluating LES Subgrid-Scale Models for High Heat Flux Flows". In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32504.
Testo completoAbstract (sommario):
This work is concerned with the modeling of a strongly heated, low Mach number, gas flowing upward within a vertical tube with constant heat flux boundary conditions. Four large eddy subgrid models are compared in their ability to predict the temperature distribution in the heated pipe. All LES models predict the mean velocity profile reasonably well. The RMS values of the Smagorinsky-Lilly model and the WALE model show the same shape but different magnitude while the standard Smagorinsky model shows the maximum at a different location. The mean temperature profiles along the wall in the section with the prescribed heat flux are underpredicted by all LES models.
9
Yellowhair, Julius, e Charles E. Andraka. "Projection of Flat-Plane Fluxmap Images Onto Non-Flat Receiver Surfaces". In ASME 2011 5th International Conference on Energy Sustainability. ASMEDC, 2011. http://dx.doi.org/10.1115/es2011-54153.
Testo completoAbstract (sommario):
When designing or evaluating a dish concentrator system, it is desirable to determine the incident flux profile on the receiver surface, regardless of the absorber surface geometry. During the design process, analytical tools are used to predict flux profiles. During product evaluation, a flux-mapper (beam characterization system) can be used to measure the flux profile on a flat target surface. Radiosity concerns typically limit flux mapping measurements of dish-engine systems to a flat plate target. We propose and demonstrate an analytical method to project such a measured flat-target flux profile onto a non-flat receiver surface. We analytically estimate the angular content of the flux profile, and use this estimate combined with the measured flat-plate flux profile to project an estimate of the flux pattern onto another receiver surface. In this paper, we analytically demonstrate the technique. We first model a dish concentrator using CIRCE2. We then develop an analytic flux-map, in CIRCE2, on a flat target, simulating a flux-mapper output. Next, we use our new software tool and the CIRCE2 angular flux binning to project this flux pattern onto a non-flat receiver surface. Finally, we run a CIRCE2 model of the same dish with the non-flat target geometry, and compare this CIRCE2 output to the projected data. We also demonstrate the technique using a measured flux-map from a dish system in the field.
10
Sahai, Vivek, e Salvador M. Aceves. "Analysis of Heat Transfer During Quenching of a Gear Blank". In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-1073.
Testo completoAbstract (sommario):
Abstract This paper presents experimental and numerical results for the quench of a gear blank in agitated and stagnant oil. Temperatures within the gear blank are determined with a whole domain-optimizer technique inverse solution method, to calculate the time history at every point in the gear blank. The development of this procedure represents the first stage in an overall analysis of the quench process that will later include material phase transformations and deformation. The paper presents ten variations in setting up the inverse problem, to analyze which combination of independent variables and decision variables results in the best match between experimental and numerical results. The results indicate that dividing the boundary of the gear blank into four zones and assigning a fixed heat transfer coefficient or heat flux to each zone yields an average RMS error (average difference between experimental and numerical results) of the order of 40 K. This error can be reduced by either increasing the number of zones, by reducing the number of thermocouples being matched, or by allowing the heat transfer or heat flux to vary within the zones. Of these possibilities, variation of heat transfer within the zones gives the best improvement in the quality of the match for the amount of extra computational effort required to run the problem.
Rapporti di organizzazioni sul tema "RMN en flux"
1
Aceves, S., V. Sahai e W. Stein. Explanation of how to run the global local optimization code (GLO) to find surface heat flux. Office of Scientific and Technical Information (OSTI), marzo 1999. http://dx.doi.org/10.2172/8214.
Testo completo
2
Donna P. Guillen. As-Run Thermal Analysis of the GTL-1 Experiment Irradiated in the ATR South Flux Trap. Office of Scientific and Technical Information (OSTI), maggio 2011. http://dx.doi.org/10.2172/1027935.
Testo completo
3
Dejus, R. Effect of emittance and rms phase error on angular flux density and pinhole flux-a simulation study of two undulators at 10.5 mm gap including very high harmonics. Office of Scientific and Technical Information (OSTI), marzo 2004. http://dx.doi.org/10.2172/822558.
Testo completo
4
Taylor, S., J. Lever, K. Burgess, R. Stroud, D. Brownlee, L. Nittler, A. Bardyn et al. Sampling interplanetary dust from Antarctic air. Engineer Research and Development Center (U.S.), febbraio 2022. http://dx.doi.org/10.21079/11681/43345.
Testo completoAbstract (sommario):
We built a collector to filter interplanetary dust particles (IDPs) larger than 5 µm from the clean air at the Amundsen Scott South Pole station. Our sampling strategy used long duration, continuous dry filtering of near-surface air in place of short duration, high-speed impact collection on flags flown in the stratosphere. We filtered ~107 m³ of clean Antarctic air through 20 cm diameter, 3 µm filters coupled to a suction blower of modest power consumption (5–6 kW). Our collector ran continuously for 2 years and yielded 41 filters for analyses. Based on stratospheric concentrations, we predicted that each month’s collection would provide 300–900 IDPs for analysis. We identified 19 extraterrestrial (ET) particles on the 66 cm² of filter examined, which represented ~0.5% of the exposed filter surfaces. The 11 ET particles larger than 5 µm yield about a fifth of the expected flux based on >5 µm stratospheric ET particle flux. Of the 19 ET particles identified, four were chondritic porous IDPs, seven were FeNiS beads, two were FeNi grains, and six were chondritic material with FeNiS components. Most were <10 µm in diameter and none were cluster particles. Additionally, a carbon-rich candidate particle was found to have a small ¹⁵N isotopic enrichment, supporting an ET origin. Many other candidate grains, including chondritic glasses and C-rich particles with Mg and Si and FeS grains, require further analysis to determine if they are ET. The vast majority of exposed filter surfaces remain to be examined.
5
Turekian, K. K. (The determination of sup 222 Rn flux from soils based on sup 210 Pb and sup 226 Ra disequilibrium). Office of Scientific and Technical Information (OSTI), gennaio 1991. http://dx.doi.org/10.2172/5811774.
Testo completo
6
Mondragon, Tomas, Jeffrey Allen, Reena Patel e Oliver-Denzil Taylor. Comparison of numerical simulations of heat-induced stress in basalt. Engineer Research and Development Center (U.S.), settembre 2024. http://dx.doi.org/10.21079/11681/49191.
Testo completoAbstract (sommario):
Energy losses due to excessive noise and heat are primary liabilities in traditional mining processes. Some of the currently researched methods to improve these liabilities involve heating the rock to induce internal stress fractures that make it easier to extract or remove rock with traditional mining equipment. Physical experimentation has yielded useful data that have been applied to numerical simulations of the heating and fracturing of rock, and multiple such simulations have been developed in the commercial multiphysics simulator COMSOL. Since COMSOL is not widely available on DoD high-performance computers, the goal of this research is to develop methods of replicating simulations developed in COMSOL as simulations that run in Abaqus FEA, another commercial multiphysics simulator. In this work, a simulated basalt cylinder with a 25 mm radius and a 158 mm height is subjected to a surface heat flux approximating the effects of a laser beam applied to the top of the cylinder. Simulated stress distributions, displacements, and temperatures obtained from both simulators are compared. When comparable results were not obtained using both simulators, the differences in results were investigated using simplified versions of the simulation.
7
Kamai, Tamir, Gerard Kluitenberg e Alon Ben-Gal. Development of heat-pulse sensors for measuring fluxes of water and solutes under the root zone. United States Department of Agriculture, gennaio 2016. http://dx.doi.org/10.32747/2016.7604288.bard.
Testo completoAbstract (sommario):
The objectives defined for this study were to: (1) develop a heat-pulse sensor and a heat-transfer model for leaching measurement, and (2) conduct laboratory study of the sensor and the methodology to estimate leaching flux. In this study we investigated the feasibility for estimating leachate fluxes with a newly designed heat-pulse (HP) sensor, combining water flux density (WFD) with electrical conductivity (EC) measurements in the same sensor. Whereas previous studies used the conventional heat pulse sensor for these measurements, the focus here was to estimate WFD with a robust sensor, appropriate for field settings, having thick-walled large-diameter probes that would minimize their flexing during and after installation and reduce associated errors. The HP method for measuring WFD in one dimension is based on a three-rod arrangement, aligned in the direction of the flow (vertical for leaching). A heat pulse is released from a center rod and the temperature response is monitored with upstream (US) and downstream (DS) rods. Water moving through the soil caries heat with it, causing differences in temperature response at the US and DS locations. Appropriate theory (e.g., Ren et al., 2000) is then used to determine WFD from the differences in temperature response. In this study, we have constructed sensors with large probes and developed numerical and analytical solutions for approximating the measurement. One-dimensional flow experiments were conducted with WFD ranging between 50 and 700 cm per day. A numerical model was developed to mimic the measurements, and also served for the evaluation of the analytical solution. For estimation WFD, and analytical model was developed to approximate heat transfer in this setting. The analytical solution was based on the work of Knight et al. (2012) and Knight et al. (2016), which suggests that the finite properties of the rods can be captured to a large extent by assuming them to be cylindrical perfect conductors. We found that: (1) the sensor is sensitive for measuring WFD in the investigated range, (2) the numerical model well-represents the sensor measurement, and (2) the analytical approximation could be improved by accounting for water and heat flow divergence by the large rods.
8
Turekian, K. K. [The determination of {sup 222}Rn flux from soils based on {sup 210}Pb and {sup 226}Ra disequilibrium]. Progress report. Office of Scientific and Technical Information (OSTI), dicembre 1991. http://dx.doi.org/10.2172/10116847.
Testo completo
9
Keller, David P., Neha Mehendale e Tronje P. Kemena. Analysis (report) of high- resolution modelling of efficacy, and regional impacts of selected ocean NETs close to the deployment sites. OceanNets, novembre 2023. http://dx.doi.org/10.3289/oceannets_d4.3_v1.
Testo completoAbstract (sommario):
Many recent ocean modelling studies have demonstrated the added value of enhanced horizontal resolution, although it comes at a high computational cost. However, few modeling studies of ocean-based CDR have been done at high resolution. Here we assess the effects of model resolution on two simulated ocean-based CDR methods, unequilibrated ocean alkalinity enhancement (OAE) and the direct marine capture (DMC) of CO2 from seawater (with assumed permanent storage), in experiments with the FOCI Earth system model. To do this we utilized two FOCI configurations, one with a 1/2° ocean resolution and the other with a 1/10° ocean nest in the N. Atlantic. Both configurations were run in a series of “paired” experiments with identical climate forcing and CDR deployments. We show that model resolution does appear to matter when simulating OAE and DMC. For OAE, parameterization of physical processes in the coarse resolution version of the model appears to overestimate how long alkalized waters stay in contact with the atmosphere and where they are transported. This results in large differences in OAE efficacy with almost twice as much carbon sequestered when the model resolution is coarse. For the DMC simulations, at one site there were clear differences in the compensating CO2 flux induced by DIC removal, which was again higher with a coarse resolution, while at the other site variability was high and differences were difficult to determine. At both DMC sites there were clear differences in circulation with the two model resolutions, and thus on downstream biogeochemistry. We suggest that well resolving ocean physics may be necessary to best calculate unequilibrated OAE and DMC efficacies and side effects. These results should be confirmed using other models and with different resolutions.