Relevant bibliographies by topics / Thermal crossover

Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers

Academic literature on the topic 'Thermal crossover'

Author: Grafiati
Published: 28 September 2022
Last updated: 23 October 2022

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Journal articles on the topic "Thermal crossover"

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Wang, Jian, and Jian-Sheng Wang. "Dimensional crossover of thermal conductance in nanowires." Applied Physics Letters 90, no. 24 (June 11, 2007): 241908. http://dx.doi.org/10.1063/1.2748342.

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Bushuev, Mark B. "Kinetics of spin crossover with thermal hysteresis." Physical Chemistry Chemical Physics 20, no. 8 (2018): 5586–90. http://dx.doi.org/10.1039/c7cp08554k.

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Grossmann, Siegfried, and Victor S. L’vov. "Crossover of spectral scaling in thermal turbulence." Physical Review E 47, no. 6 (June 1, 1993): 4161–68. http://dx.doi.org/10.1103/physreve.47.4161.

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Halcrow, Malcolm A. "Spin-crossover Compounds with Wide Thermal Hysteresis." Chemistry Letters 43, no. 8 (August 5, 2014): 1178–88. http://dx.doi.org/10.1246/cl.140464.

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Desmarest, Ph, and R. Tufeu. "Thermal diffusivity and thermal conductivity of steam in the crossover region." International Journal of Thermophysics 11, no. 6 (November 1990): 1035–46. http://dx.doi.org/10.1007/bf00500558.

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Kou, S. P., J. Q. Liang, Y. B. Zhang, X. B. Wang, and F. C. Pu. "Crossover from thermal hopping to quantum tunneling inMn12Ac." Physical Review B 59, no. 9 (March 1, 1999): 6309–16. http://dx.doi.org/10.1103/physrevb.59.6309.

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Laermans, C., and D. A. Parshin. "Tunneling–thermal activation crossover in neutron irradiated quartz." Physica B: Condensed Matter 263-264 (March 1999): 143–45. http://dx.doi.org/10.1016/s0921-4526(98)01320-9.

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Real, José Antonio, Ana Belén Gaspar, and M. Carmen Muñoz. "Thermal, pressure and light switchable spin-crossover materials." Dalton Transactions, no. 12 (2005): 2062. http://dx.doi.org/10.1039/b501491c.

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Bodapati, Arun, Pawel Keblinski, Patrick K. Schelling, and Simon R. Phillpot. "Crossover in thermal transport mechanism in nanocrystalline silicon." Applied Physics Letters 88, no. 14 (April 3, 2006): 141908. http://dx.doi.org/10.1063/1.2192145.

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Lambaré, H., P. Roche, E. Rolley, S. Balibar, C. Guthmann, and H. J. Maris. "Crossover from quantum to thermal cavitation in superfluid4He." Czechoslovak Journal of Physics 46, S1 (January 1996): 383–84. http://dx.doi.org/10.1007/bf02569607.

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Dissertations / Theses on the topic "Thermal crossover"

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Billon, Alice. "Rheology of dense suspensions in the thermal crossover." Thesis, Aix-Marseille, 2021. http://www.theses.fr/2021AIXM0634.

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Les suspensions de sphères dures se rencontrent en géophysique, dans l’industrie et même en biologie. À première vue ce sont des systèmes assez simples, mais le très grand nombre de particules en jeu ainsi que la complexité des contacts et des interactions électrostatiques et hydrodynamiques entre particules qui jouent un rôle non négligeable dès que la suspension est dense en font un objet d’étude compliqué, même pour le cas de particules sphériques dans un fluide newtonien. Jusqu’à présent, deux régimes distincts ont été largement étudiés : les sphères dures athermiques frictionnelles, pour lesquelles les forces électrostatiques et de Van der Waals sont négligeables, et les suspensions colloïdales, pour lesquelles l’agitation thermique domine. Ces deux régimes sont des cas limites contrôlés soit par la pression de confinement, soit par l’agitation thermique. Les écoulements où les deux sont du même ordre manquent encore d’une description complète, malgré leur importance cruciale dans l’étude des écoulements réels. En s’inspirant des expériences de plan incliné macroscopiques, nous avons conçu un plan incliné microscopique sous observation confocale, sur lequel nous faisons couler des suspensions micrométriques. Les profils de vitesse obtenus sont comparés à un modèle théorique qui éclaire la transition entre les régimes athermique et colloïdal. Pour compléter notre étude, nous avons aussi mis au point une expérience d’écoulement sur tas microscopique, avec des réseaux de tambours micrométriques immergés, remplis par nos suspensions micrométriques, pour mesurer leur angle de repos
Hard spheres suspensions are present in a wide range of geophysical, industrial and even biological domains. They might seem very simple systems at first sight, but the number of particles and the complexity of interparticulate contacts, electrostatic and hydrodynamic forces as soon as the suspension is dense makes it a very tough object to study, even for spherical particles in a Newtonian fluid. Until now, two distinct cases have been widely studied: frictional athermal spheres, for which electrostatic and Van derWaals forces are negligible, and colloidal suspensions, where thermal agitation dominates. These two regimes are limit cases controlled either bythe confining pressure or by thermal motion. Flows for which both stresses are of the same order of magnitude are still lacking a complete description, despite their crucial importance in understanding realistic flows. Inspired by macroscopic inclined plane experiments, we designed a microscopic inclined plane under confocal observation, using micron-size suspensions. We compare the experimental velocity profiles with a theoretical model which enlights the transition between granular and colloidal regimes. To complete our investigation, we also set up a microscopic heap flow experiment with immersed micro drums arrays filled with our micron-size suspension to track the angle of repose
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Raza, Yousuf. "Spin Crossover Nanoparticles of Fe (pyrazine) [Pt(CN)4] : Role of Environment on Thermal Bistability." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112042.

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Ce travail a porté sur la synthèse et l'étude de nanoparticules à transition de spin du réseau tridimensionnel Fe(pyrazine)[Pt(CN)4]. L'objectif principal de ce travail était d’étudier l’effet de l'environnement (matrice) sur les propriétés de transition de spin des nanoparticules de Fe(pyrazine)[Pt(CN)4]. Dans un premier temps, la synthèse en microémulsion et l’étude de quelques paramètres permettant de varier la taille des particules ont été menées. La morphologie de deux tailles de particules a été étudiée en particulier par tomographie électronique. Les propriétés des particules de Fe(pyrazine)[Pt(CN)4] de 10 nm récupérées sans enrobage sont présentées et révèlent une coopérativité comparable au composé massif. L’étude a ensuite été poursuivie en modifiant uniquement l'environnement des particules en gardant les autres paramètres (taille, composition, forme) constants. Des particules de Fe(pyrazine)[Pt(CN)4] de 10 nm ont été protégées par différentes molécules telles qu’un dérivé calix-8-arène comportant des pyridines, le para-nitrobenzylpyridine (pNBP), un polymère (PVP) ou encore par croissance par voie sol-gel d’une coquille de silice de différentes épaisseurs. L’effet de l’environnement des nanoparticules sur les propriétés de transition de spin a été mis en évidence de manière très claire et la compressibilité de la matrice a été proposée comme élément permettant de moduler cette coopérativité. Par ailleurs, l'influence de la nature du réseau inorganique modifié par insertion d’iode dans le réseau de Fe(pyrazine) [Pt(CN)4] des nanoparticules a été étudiée, afin d’augmenter la température de transition autour de l’ambiante. Un effet particulièrement important été observé sur la coopérativité de la transition de spin des particules enrobées. Les résultats ont été discutés dans le contexte de récentes études de modélisation
This work is focused on the synthesis and study of the spin crossover nanoparticles of 3D Fe (pyrazine) [Pt(CN)4] network. The main objective of this work was to study the environment (matrix) effects on the spin crossover (SCO) behavior of the Fe(pyrazine)[Pt(CN)4] nanoparticles. At first, microemulsion synthesis and study of some parameters affecting the size of the particles have been conducted. The morphology of particles of two sizes has been studied in particular using Electron Tomography. The properties of the 10 nm Fe(pyrazine)[Pt(CN)4] particles recovered without coating are presented and reveal cooperativity comparable to the bulk compound. The study was followed by changing only the environment and keeping other parameters (size, composition, shape) constant. 10 nm Fe(pyrazine)[Pt(CN)4] nanoparticles were protected by different molecules such as a derivative of calix-8-arene having pyridine groups, para-nitrobenzylpyridine (pNBP), a polymer (PVP) or a silica shell of different thicknesses grown via sol-gel process. The effect of the environment of nanoparticles on the spin transition properties has been demonstrated very clearly and the compressibility of the matrix has been proposed as an element to modulate the cooperativity. In addition, the influence of the nature of the inorganic network modified by insertion of iodine in the network Fe(pyrazine)[Pt(CN)4] nanoparticles has been studied to increase the transition temperature around ambient temperature. A particularly significant effect was observed on the cooperativity of the spin transition of the coated particles. The results were discussed in the context of recent modelisation studies
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Watashige, Tatsuya. "Quasiparticle excitations in FeSe in the vicinity of BCS-BEC crossover studied by thermal transport measurements." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225391.

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Alfurayj, Ibrahim A. "Solid-state Spin Equilibrium in Tetrakis(N,N'-diethylthiourea)nickel(II) dichloride, [Ni(detu)4]Cl2: Structural and Thermal Characterization." Ohio University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1435790988.

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Kraieva, Olena. "New approaches for high spatial and temporal resolution nanothermometry : development of hot wire nano heater devices and investigation of thermosensitive materials with fluorescent and spin crossover properties." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30315.

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L'objectif de cette thèse était de développer de nouvelles méthodes micro- et nano-thermométriques proposant de hautes résolutions spatiales et temporelles. Dans ce cadre nous nous sommes concentrés sur deux tâches : dans un premier temps, nous avons développé un dispositif de nano-chauffage qui peut aisément servir à la caractérisation thermo-physique de matériaux à l'échelle nanométrique. Dans un second temps, en utilisant cette plate-forme nous avons étudié des matériaux thermosensibles, incluant divers luminophores et des complexes à transition de spin ainsi que leurs mélanges. Les dispositifs de nano-chauffage, basés sur des nanofils chauffés par effet Joule, ont été fabriqués par lithographie électronique conventionnelle. Grâce à leur faible inertie thermique, les dispositifs basés sur des nanofils sont particulièrement intéressants en termes de temps de réponse et de confinement des changements de température induits. La caractérisation thermique de ces éléments de chauffage a été réalisée à l'aide de méthodes électriques et optiques ainsi que de simulations par éléments finis. Nous avons montré expérimentalement que nos chauffages prodiguent des perturbations en température (1 K < DeltaT < 80 K) rapides (< µs) et spatialement localisées (< µm) lorsque stimulées par des impulsions de courant électrique. Les simulations par éléments finis reproduisent ces résultats expérimentaux avec une bonne précision et prouvent ainsi leur intérêt pour le design de tels dispositifs. Les performances thermométriques de matériaux fluorescents, incluant des colorants organiques (Rhodamine B), des nanoparticules inorganiques (PbF2:Er3+/Yb3+, CdSe) et des nanoparticules hybrides organiques/inorganiques ([Fe(Htrz)2(trz)]BF4@SiO2-pyrene), ont ensuite été étudiées. D'une manière générale, leur intérêt pour l'imagerie thermique a été démontré, mais des problèmes de stabilité rendent les mesures quantitatives difficiles avec de tels matériaux. D'un autre côté, nous avons réussi à synthétiser des films de nanoparticules du complexe à transition de spin [Fe(Htrz)2(trz)]BF4 (non-dopé). Ces films qui nous ont permis de suivre les changements de température à l'aide de mesures de réflectivité optique plus robustes. La boucle d'hystérèse thermique dans ce matériau procure un effet de mémoire thermique à long terme dont nous avons usé avec succès pour imager les changements de température très rapides (< µs) et spatialement localisés (< µm) - même après que la chaleur se soit dissipée. Cette méthode originale nous procure une combinaison sans précédent de sensitivité spatio-temporelle dans le champ de la nano-thermométrie aux applications pratiques prometteuses
The overall objective of this PhD thesis was to develop novel micro- and nano-thermometry methods providing high spatial and temporal resolution thermal imaging. To achieve this goal we have focused on two tasks: First, we developed a nano-heater device that can be easily employed for the thermo-physical characterization of materials at the nanoscale. In a second time, using this platform we investigated thermo-sensitive materials, including different luminophores and spin crossover complexes as well as their mixtures. The nano-heater device, based on Joule-heated metallic nanowires, was fabricated by standard electron beam lithography. Due to their small thermal mass, nanowire based devices are particularly interesting in terms of response times and also in terms of confinement of the induced temperature changes. The thermal characterization of these heating elements was carried out using electrical and optical methods as well as finite element simulations. We have shown experimentally that our heaters can provide fast (< µs) and spatially well localized (< µm) T-jump perturbations (1 K < DeltaT < 80 K) driven by an electrical current pulse. Finite element simulations reproduced these experimental results with good accuracy and proved to be a powerful tool of prediction for the device design. Fluorescent materials, including organic dyes (Rhodamine B), inorganic nanoparticles (PbF2:Er3+/Yb3+, CdSe) and hybrid organic/inorganic nanoparticles ([Fe(Htrz)2(trz)]BF4@SiO2-pyrene), were then investigated for their thermometry performance. Overall, they were found useful for thermal imaging, but stability problems make quantitative measurements challenging with these materials. On the other hand, we have succeeded in synthesizing nanoparticle films of the (undoped) [Fe(Htrz)2(trz)]BF4 spin crossover complex, which allowed us to infer temperature changes through more robust optical reflectivity measurements. The thermal hysteresis loop in this material provides a long-term thermal memory effect which we used successfully to image very fast (˜µs) transient temperature changes with high spatial resolution (sub-µm) - even when the heat is dissipated. This original method provides an unprecedented combination of spatio-temporal sensitivity within the field of nanothermometry with promising potential applications
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Suleimanov, Iurii. "Nano-objets et nano-composites à transition de spin basés sur des complexes du fer(II) avec des ligands 1,2,4-triazoles." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30017.

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L'échelle moléculaire est de plus en plus considérée comme une solution alternative pour la miniaturisation des composants électroniques en vue de la construction de dispositifs fonctionnels. L'approche actuelle "top-down" basée sur la technologie du silicium force les chimistes du solide, les physiciens et les électroniciens à manipuler progressivement des quantités de matière de plus en plus faibles. Dans ce domaine, les dispositifs moléculaires offrent des perspectives remarquables avec des niveaux de sensibilité et de sélectivité qui ne peuvent pas être atteints avec les matériaux à semi-conducteurs conventionnels. Dans ce contexte, les complexes ou polymères de coordination représentent une classe importante de composés possédant des propriétés de commutation magnétiques, optiques et électrochimiques intéressantes. En particulier, les composés à transition de spin (transition intra-métallique de l'état haut spin vers l'état bas spin) des métaux de transition sont bien adaptés à cette stratégie car ils peuvent être le siège d'une transition réversible du premier ordre avec hystérésis sous l'effet d'une perturbation extérieure (température, pression ou éclairement) impliquant des modifications magnétique, optique et structurale. Dans ces travaux de thèse, des matériaux susceptibles de présenter des propriétés de bistabilité avec hystérésis autour de la température ambiante sont présentés et discutés. Un des objectifs est d'étudier l'évolution de leurs propriétés en fonction de la taille et de valoriser ces matériaux. Pour cela, ces composés ont été nano-structurés. Ainsi nous avons élaboré des nanoparticules à base de composé à transition de spin par différentes voies de synthèse et réalisé des films minces et des nanostructures de ces matériaux par des méthodes de lithographie douce et de lithographie électronique. Pour caractériser les propriétés de ces nouveaux objets, nous nous sommes orienté vers l'utilisation de nouvelles techniques de détection optiques et en particulier vers des techniques qui permettent la mesure de la variation du changement d'indice optique de ces matériaux, à savoir, des mesures de la variation des plasmons de surface lorsque des couches minces bistables de ces composés sont mises au contact de surface d'or et des mesures de variation de l'efficacité de diffraction à partir de réseaux de motifs de tailles micro- et nanométriques. Par ailleurs, une méthode basée sur la variation de l'intensité de fluorescence d'un fluorophore sélectionné et intégré au sein de composé mixte (composé à transition de spin - fluorophore) a également été développée. L'ensemble de ces méthodes concourt à pouvoir détecter un objet unique de taille nanométrique
The thesis is devoted to the preparation of new nanoobjects and nanocomposites of spin crossover complexes [Fe(Htrz)2(trz)](BF4) and [Fe(NH2-trz)3](NO3)2 (where Htrz - 1,2,4-triazole, trz - 1,2,4-trazolato, NH2-trz - 4-amino-1,2,4-triazole) and investigation their properties. Nanoobjects of mixed-ligand complexes with different ratio of 4-amino-1,2,4-triazole to 1,2,4-triazole were synthesized in reverse emulsions. It was shown that the increasing of the of 4-amino-1,2,4-triazole quantity leads to the increasing of nanoparticles anisotropy while spin crossover temperatures decrease. Double-step spin transition was observed at 20% mol of 4-amino-1,2,4-triazole, while at concentrations over 50% mol. spin crossover properties of [Fe(Htrz)2(trz)](BF4) completely disappear. Investigations of their morpholgy, size and spin transition characteristics as well as investigations of mechanisms of the fluorescent properties change under the spin switching process are shown. We consider obtaining nanoobjects of mixed-ligand complexes of iron (II) based on 1,2,4-triazole and 4-amino-1,2,4-triazole. The ligands ratio influences the morphology, size and characteristics of the spin transition of nanoobjects obtained. New modification of the complex [Fe(NH2-trz)3](NO3)2 in the form of nanoobjects was obtained using ligand excess. High transition temperature of this form was evidenced by various methods of analysis. This form was found to be isostructural with a resolved structure of [Fe(NH2-trz)3](NO3)2 · 2H2O. Series of nanocomposites with plasmonic and luminescent properties were prepares. For the core-shell composite with gold nanoparticles higher efficiency of the spin state switching due to the photothermal effect was demonstrated in comparison to the control sample. Fluorescent spin crossover composites with quantum dots, organic luminophors and terbium complexes were described. For all these composites the luminescence intensity variation as a function of temperature have been found. The mechanisms responsable of the luminescence intensity variation at two spin state are discussed. These mechanisms include resonant energy transfer, mechanical strain and photon reabsorption. High photostability fort he terbium - spin crossover composite is demonstrated comparing to previously obtained similar spin crossover luminescetnt composites. An example of a practical application of obtained composites for manufacturing fluorescent thermosensitive paper is shown
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Martinez, Felipe Alfonso. "Preparation and characterisation of new materials for electrolytes used in Direct Methanol Fuel Cells." Doctoral thesis, Universitat Politècnica de València, 2010. http://hdl.handle.net/10251/8327.

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Summary The aim of this PhD thesis is the preparation and study of new materials to be used as electrolytes in Direct Methanol Fuel Cells (DMFC) in order to reduce crossover of methanol. Different materials have been prepared, including polymer dispersed liquid crystals, crosslinked polymers with high protonic conductivity and polymeric liquid crystals. Moreover, a methodology to characterise potential new materials for their application in DMFC has been developed. The absorption properties of water and methanol in the materials have been studied in different conditions and compared with the results obtained for commercial Nafion membranes used in DFMC. The absorption and diffusion properties of water and methanol through the materials have been studied by means of Fourier Transform Infrared Spectroscopy and thermal analysis techniques. The methodology provides important information to analyse the interactions between the different functional groups of the polymers and the solvents commonly used in DMFC. Finally, a device has been designed and set-up to analyse the effect on crossover of methanol of the electro-osmotic drag and the polarisation of the polymeric electrolytes.
Martinez Felipe, A. (2009). Preparation and characterisation of new materials for electrolytes used in Direct Methanol Fuel Cells [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8327
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Jeftić, Jelena. "The influence of pressure on the thermal equilibrium and the relaxation dynamics in the iron(II) spin-crossover systems : [Zn1-xFex(ptz)6](BF4)2 and [Fe(ptz)6](PF6)2, (x = 0.1, 0.32 and 1, ptz = 1-n-propyltetrazole) /." [S.l.] : [s.n.], 1997. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.

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Armijo, Julien. "Fluctuations de densité dans des gaz de bosons ultafroids quasi-unidimensionnels." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00601066.

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Cette thèse présente la conception et l'implémentation d'une nouvelle génération de puces à atomes, ouvrant de nouvelles perspectives expérimentales dans des micropièges magnétiques très anisotropes. Les propriétés thermiques des puces en nitrure d'aluminium sont étudiées en détail. Le dispositif a été optimisé pour piéger de plus grands nombres d'atomes et améliorer la qualité de l'imagerie, notamment en fabriquant un miroir de planéité sub-λ/10 à la surface de la puce.Nous étudions des gaz quasi-1D grâce à des images in situ de profils fluctuants et des méthodes précises de calibration et d'analyse statistique. Nous mesurons des fluctuations non-gaussiennes, ce qui permet de tester sensiblement la thermodynamique du gaz et donne une mesure de corrélations à trois corps. Nous étudions précisément la transition de quasicondensation et mesurons pour la première fois sa loi d'échelle. En régime 3D, c'est une condensation transverse qui déclenche la quasicondensation longitudinale, tandis qu'en régime 1D, la formation d'un quasicondensat est gouvernée par les interactions répulsives et non par la dégénérescence quantique.Obtenant des températures record pour des gaz 1D, nous observons des fluctuations subpoissoniennes lorsque les corrélations atomiques sont déterminées, au moins localement, par les fluctuations quantiques qui dominent les fluctuations thermiques. Nous discutons également la thermalisation étonnamment rapide mesurée en régime 1D profond qui suggère que des collisions effectives à 3 corps brisent l'intégrabilité du système.
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Hoefer, Andreas. "Vibrational spectroscopy on thermally and optically switchable spin crossover compounds." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=960457364.

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Books on the topic "Thermal crossover"

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United States. National Aeronautics and Space Administration., ed. Studying the thermal/non-thermal crossover in solar flares: Final report, NRA-92-OSSA-17. [Washington, DC: National Aeronautics and Space Administration, 1994.

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United States. National Aeronautics and Space Administration., ed. Studying the thermal/non-thermal crossover in solar flares: Final report, NRA-92-OSSA-17. [Washington, DC: National Aeronautics and Space Administration, 1994.

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United States. National Aeronautics and Space Administration., ed. Studying the thermal/non-thermal crossover in solar flares: Final report, NRA-92-OSSA-17. [Washington, DC: National Aeronautics and Space Administration, 1994.

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Book chapters on the topic "Thermal crossover"

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Uehara, Mitsuru. "Crossover from Thermal to Quantum Regime in Vortex Motion in Conventional Type II Superconductors." In Quantum Tunneling of Magnetization — QTM ’94, 455–69. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0403-6_25.

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Nishino, Masamichi, Kamel Boukheddaden, Seiji Miyashita, and François Varret. "Dynamical Properties of Photoinduced Magnetism and Spin-Crossover Phenomena in Prussian Blue Analogs - Photoinduced Thermal Hysteresis of Magnetization -." In Solid State Phenomena, 73–80. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/3-908451-19-1.73.

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Gaspar, Ana B., M. Carmen Muñoz, Nicolás Moliner, Vadim Ksenofontov, Georgii Levchenko, Philipp Gütlich, and José Antonio Reall. "Polymorphism and Pressure Driven Thermal Spin Crossover Phenomenon in [Fe(abpt)2(NCX)2] (X=S, and Se): Synthesis,Structure and Magnetic Properties." In Molecular Magnets Recent Highlights, 169–78. Vienna: Springer Vienna, 2002. http://dx.doi.org/10.1007/978-3-7091-6018-3_12.

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Christov, S. G. "The Characteristic (Crossover) Temperature in the Theory of Thermally Activated Tunneling Processes." In Quantum Systems in Chemistry and Physics. Trends in Methods and Applications, 109–47. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-4894-8_7.

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Shakirova, Olga G. "Thermally Induced Spin Crossover in Iron (II, III) Complexes with Tripodal Ligands." In Current Problems and Ways of Industry Development: Equipment and Technologies, 319–30. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-69421-0_34.

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Coffey, W. T., D. A. Garanin, and D. J. Mccarthy. "Crossover formulas in the kramers theory of thermally activated escape rates-application to spin systems." In Advances in Chemical Physics, 483–765. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470141779.ch5.

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"Crossover from thermal to quantum decay." In Quantum Dissipative Systems, 265–72. 5th ed. World Scientific, 2021. http://dx.doi.org/10.1142/9789811241505_0014.

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"Landscape Influences on Stream Habitats and Biological Assemblages." In Landscape Influences on Stream Habitats and Biological Assemblages, edited by Christian E. Torgersen, Colden V. Baxter, Hiram W. Li, and Bruce A. McIntosh. American Fisheries Society, 2006. http://dx.doi.org/10.47886/9781888569766.ch23.

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<em>Abstract.</em>—Longitudinal analysis of the distribution and abundance of river fishes provides a context-specific characterization of species responses to riverscape heterogeneity. We examined spatially continuous longitudinal profiles (35–70 km) of fish distribution and aquatic habitat (channel gradient, depth, temperature, and water velocity) for three northeastern Oregon rivers. We evaluated spatial patterns of river fishes and habitat using multivariate analysis to compare gradients in fish assemblage structure among rivers and at multiple spatial scales. Spatial structuring of fish assemblages exhibited a generalized pattern of cold- and coolwater fish assemblage zones but was variable within thermal zones, particularly in the warmest river. Landscape context (geographic setting and thermal condition) influenced the observed relationship between species distribution and channel gradient. To evaluate the effect of spatial extent and geographical context on observed assemblage patterns and fish–habitat relationships, we performed multiple ordinations on subsets of our data from varying lengths of each river and compared gradients in assemblage structure within and among rivers. The relative associations of water temperature increased and channel morphology decreased as the spatial scale of analysis increased. The crossover point where both variables explained equal amounts of variation was useful for identifying transitions between cool- and coldwater fish assemblages. Spatially continuous analysis of river fishes and their habitats revealed unexpected ecological patterns and provided a unique perspective on fish distribution that emphasized the importance of habitat heterogeneity and spatial variability in fish–habitat relationships.
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Nayak, Ratikanta, Bentham Science Publisher Harilal, and Prakash Chandra Ghosh. "Polymer Nanocomposite Membrane for Fuel cell Applications." In Current and Future Developments in Nanomaterials and Carbon Nanotubes, 176–89. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815050714122030013.

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Polymer nanocomposite is a new kind of material that offers to substitute traditionally filled polymers. The nanomaterial polymer matrix inter-phase area increases drastically due to the inherent high surface-to-volume ratio resulting in remarkably enhanced properties compared to the pristine polymers or their conventional counterpart filled nanocomposites. Nanocomposites have several novel properties such as nonlinear optical properties, electronic conductivity and luminescence. Therefore, their use has been projected in many areas like chemical sensors, polymer electrolyte membrane fuel cell (PEMFCs), electroluminescent devices, batteries, electrocatalysis, smart windows and memory devices. PEMFCs embody a potential candidate for electrochemical energy generation in the twenty-first century due to their better efficiency and environmentally friendly nature. Proton exchange/Polymer electrolyte membrane (PEM) plays a vital role in the PEMFCs. Currently, PEM like Nafion and Flemions are widely used in PEMFC, which have certain drawbacks such as fuel cross-over through the membrane, low operating temperature, and high cost. The researchers from several laboratories across the globe have put their extreme effort into preparing a novel polymer electrolyte membrane with high proton conductivity, better long-term stability, improved thermal stability, high peak power density (PPD), and less fuel crossover with minimum cost. The advent of nanotechnology has brought a new scope to this research area. The hybrid (organic polymer with inorganic nanoparticle) nanocomposite membrane has developed into an exciting alternative to the conventional polymer membrane applications. It provides an exclusive blend of inorganic and organic properties and helps to overcome the drawbacks of align="center"pristine polymer membranes. In this book chapter, we have focused on different nanomaterials and their effect is analyzed in polymer electrolyte nanocomposite membranes for PEMFC applications.
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Conference papers on the topic "Thermal crossover"

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Retief, S. J. Paul, C. J. Willers, and M. S. Wheeler. "Prediction of thermal crossover based on imaging measurements over the diurnal cycle." In AeroSense 2003, edited by Nickolas L. Faust and William E. Roper. SPIE, 2003. http://dx.doi.org/10.1117/12.488358.

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Misaki, Y., A. Saito, and K. Hamasaki. "Crossover of Noise Power from Thermal to Shot Noise in Superconducting Mesoscopic Devices." In 1995 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics, 1995. http://dx.doi.org/10.7567/ssdm.1995.pd-1-5.

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Hughes, Katherine W. "Effect of Thermal Mass and Aging on CO-NOx Crossover and Light Off Behavior." In SAE 2005 World Congress & Exhibition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2005. http://dx.doi.org/10.4271/2005-01-1106.

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Kulkarni, M. R. "Critical Radius for Radial Heat Conduction: A Necessary Criterion but Not Always Sufficient." In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-1140.

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Abstract Use of the critical radius for radial heat conduction in thermal insulation systems has been widely reported in the literature. When it is desirable to increase heat dissipation, this critical radius can be used in a definitive manner to maximize the heat dissipation. However, if it is desirable to decrease heat gain or heat loss, the critical radius only serves as a necessary condition, but it is not sufficient. To address design of such thermal systems, a new crossover radius is introduced. A crossover radius is a radius greater than the critical radius and is defined such that the heat transfer with the corresponding amount of insulating material is equal to that of the bare thermal system. Both cylindrical and spherical systems are considered.
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Mayer, Luke J., and Darryl L. James. "Experimental Analysis of Flow Crossover in a Solar Thermochemical Reactor." In ASME 2012 10th International Conference on Fuel Cell Science, Engineering and Technology collocated with the ASME 2012 6th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/fuelcell2012-91398.

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As energy and fuel security continue to be of increasing importance to economies around the world, countries are looking to move away from oil dependency. Energy solutions are being sought in the area of solar fuels to meet these growing needs. Concentrated solar thermochemical technology has the potential to directly convert sunlight into a useable, carbon-neutral liquid fuel that can be easily stored and integrated into our existing forms of energy demand such as transportation and heating fuels. Ongoing research performed by several groups at Sandia National Laboratories seeks to fundamentally understand the complex physics and chemistry occurring within a solar thermochemical reactor prototype named the CR5 [counter-rotating-ring receiver/reactor/recuperator]. The CR5 utilizes a stack of counter-rotating disks with metal oxide reactive material fins which are cycled through oxidation and reduction zones. The metal oxide is thus used to reduce H2O and CO2 into H2 and CO respectively, which can be combined using known processes to form a liquid fuel. The effectiveness of such a solar thermochemical reactor depends on its ability to efficiently integrate reduction and oxidation reactions, a solar receiver, thermal recuperation, and separation of end product gases. Efficient separation of end product gases within the reactor is of critical importance as without it, the crossover of gases occurs, which results in lower reduction rates, recombination of end product gases, and additional energy spent in downstream processes. A validation reactor model called the CR5v (v for validation) has been fabricated to validate numerical models of the reactor processes. Crossover testing is done without any chemical reactions (therefore with no O2 or H2 present), but rather by examining the flow of CO2 and Argon. This work presents experimental crossover for the CR5v reactor as a function of ring rotation speed, internal purge gas, and sweep gas to injection gas ratio. Initial crossover experimental results from the CR5v reactor suggest that crossover levels are largely not affected by ring rotation, center purge or injection gas/sweep gas ratio. Argon flow remained on average at a crossover value of 52 %, while CO2 crossover levels were on average around 8 %. The crossover flow in the system is thought to be dominated by the flow rates of the two pumps used in the system and to a lesser degree, the geometry of the system.
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Elebiary, K., and M. E. Taslim. "Experimental/Numerical Crossover Jet Impingement in an Airfoil Leading-Edge Cooling Channel." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46004.

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Technological advancement in gas turbine field demands high temperature gases impacting on the turbine airfoils in order to increase the output power as well as the thermal efficiency. Leading-edge is one of the most critical and life-limiting sections of the airfoil which requires intricate cooling schemes to maintain a robust design. In order to maintain coherence with a typical external aerodynamic blade profile, cooling processes usually take place in geometrically complex internal paths where analytical approaches may not provide a proper solution. In this study, experimental and numerical models simulating the leading-edge and its adjacent cavity were created. Cooling flow entered the leading-edge cavity through the crossover ports on the partition wall between the two cavities and impinged on the internal surface of the leading edge. Three flow arrangements were tested: 1,2) flow entering from one side (root or tip) of the adjacent cavity and emerging from either the same side or the opposite side of the leading-edge cavity and 3) flow entering from one side of the adjacent cavity and emerging from both sides of the leading-edge cavity. These flow arrangements were tested for five crossover-hole settings with a focus on studying the heat transfer rate dependency on the axial flow produced by upstream crossover holes (spent air). Numerical results were obtained from a three-dimensional unstructured computational fluid dynamics model with 1.1 million hexahedral elements. For turbulence modeling, the realizable k–ε was employed in combination with enhanced wall treatment approach for the near wall regions. Other available RANS turbulence models with similar computational cost did not produce any results in better agreement with the measured data. Nusselt numbers on the nose area and the pressure/suction sides are reported for jet Reynolds numbers ranging from 8000 to 55000 and a constant crossover hole to the leading-edge nose distance ratio, Z/Dh, of 2.81. Comparisons with experimental results were made in order to validate the employed turbulence model and the numerically-obtained results. Results show a significant dependency of Nusselt number on the axial flow introduced by upstream jets as it drastically diminishes the impingement effects on the leading-edge channel walls. Flow arrangement has immense effects on the heat transfer results. Discrepancies between the experimental and numerical results averaged between +0.3% and −24.5%, however correlation between the two can be clearly observed.
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Dong, Yuan, Chi Zhang, Chenghao Diao, and Jian Lin. "First Principles Study of Interlayer Interaction Effect on Graphene Thermal Conductivity." In ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/mnhmt2019-3905.

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Abstract It is known that the interlayer van der Waals (vdW) interactions will decrease the thermal conductivity of graphene. Single layer graphene (SLG) has the highest thermal conductivities, double layer graphene (DLG) would decrease to about half of the thermal conductivity of SLG. The graphite was measured to have a thermal conductivity of about 2000 W/m-K. Some research shows that graphite differs from SLG within a factor of 2, and DLG has almost the same thermal conductivity with graphite. In theoretical aspect, how to simulate the vdW interaction between graphene layers is a long existing problem. It is only until recently that the vdW interaction is still an active topic in first principle calculations. The popular methods include the Grimme’s DFT-D, vdW-DF and vdW-DFT-R methods. The vdW-DFT-R method was further optimized to increase accuracy by Hamada and was found to predict the most accurate interlayer distance between AB-stacked graphene in our recent study. The motivation of this work is to investigate the effect of vdW interaction on the thermal conductivity of multiple layer graphene from principles. We will calculate firstly the phonon dispersion relations of multiple layer graphene with the vdW interaction included. The obtained phonon properties and force constants will be combined with the ShengBTE method to calculate the thermal conductivity. The results show how vdW interaction causes the dimensional crossover of graphene thermal conductivity.
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Ahn, Jeongmin, Paul D. Ronney, Zongping Shao, and Sossina M. Haile. "A Thermally Self-Sustaining Miniature Solid Oxide Fuel Cell." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41137.

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A thermally self-sustaining miniature power generation device was developed utilizing a single-chamber solid oxide fuel cell (SOFC) placed in a controlled thermal environment provided by a spiral counterflow “Swiss roll” heat exchanger and combustor. With the single-chamber design, fuel/oxygen crossover due to cracking of seals via thermal cycling is irrelevant and coking on the anode is practically eliminated. Appropriate SOFC operating temperatures were maintained even at low Reynolds numbers (Re) via combustion of the fuel cell effluent at the center of the Swiss roll. Both propane and higher hydrocarbon fuels were examined. Extinction limits and thermal behavior of the integrated system were determined in equivalence ratio - Re parameter space and an optimal regime for SOFC operation was identified. SOFC power densities up to 420 mW/cm2 were observed at low Re. These results suggest that single-chamber SOFC’s integrated with heat-recirculating combustors may be a viable approach for small-scale power generation devices.
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King, James P., and Robert D. Hendrix. "Investigation of Radiant Superheater Crossover Pipe Weld Cracking at Big Cajun II Station." In ASME 2002 Pressure Vessels and Piping Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/pvp2002-1319.

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This paper describes the many features of a detailed investigation into the determination of a root cause for internal cracking found in the circumferential welds of radiant superheater crossover piping lines, in the Units No. 1 and 2 boilers at Big Cajun II Station in New Roads, Louisiana. The history of inside diameter, circumferential cracks dates back to 1992. The cracking had been recorded during several outages for both units. It was discovered by use of ultrasonic shear wave testing, and verified by ultrasonic time of flight diffraction methods. During each of the ensuing unit outages, the crack depths were recorded and mapped. Repairs were undertaken by machining out the complete girth weld followed by re-welding. During the interim years cracking did re-occur at many of the weld locations. In 2000, a detailed investigation into the cause of the cracking was initiated, which resulted in recommendations for resolving the ongoing problem. This detailed study included; nondestructive testing and metallurgy of removed metal samples, boiler performance testing and analysis and stress, fatigue and fracture mechanics evaluations. The detailed background, applications and results of the many and varied testing and analytical tasks are fully described herein. The main conclusion to the root cause of the cracking is identified as fatigue caused by the combined effects of thermal and pressure cycles. Recommendations are given which address the actions needed to limit or prevent re-occurrence of the cracking, including revised boiler operating procedures. In addition, a series of fatigue crack growth curves is presented, as a monitoring toot for evaluating existing cracks in the welds.
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Anderson, Eric K., John L. Hoke, and Fred R. Schauer. "Study of a Thermal Barrier Coating in a Pulsed Detonation Engine." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-38594.

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A pulse detonation engine (PDE) works by establishing regular purge-detonation cycles. During a cycle, a point inside the detonation tube downstream of the ignition source is exposed to extreme high temperature briefly as the detonation wave passes, followed by near room temperature purge gas. As is the case for many combustion systems, minimizing unwanted heat loss in a PDE is important to maximizing efficiency. For this reason, the effect of coating the inner wall of a detonation tube with a thin, low thermal conductivity coating was studied experimentally and computationally. A three inch diameter 304 stainless steel detonation tube with 1.65 mm wall thickness was coated on the inside with a 0.635 mm thick layer of 93% Zirconium Oxide and 7% Yttrium Oxide. Experimental results were obtained operating the PDE at a frequency of 10 Hz. Temperature was measured at four points on the exterior of the detonation tube between 33 and 45 inches downstream of the ignition source. At all locations measured, the exterior tube temperature would rise from an initial ambient temperature faster with the uncoated tube until a crossover point approximately 1000–1500 cycles after the start of the experiment. After this cross over point, outer wall temperature was higher for the coated tubes, which at this point was increasing faster for the tube with the thermal barrier. To better understand the physical reason why the insulated tube always reached a higher temperature after roughly 1000 cycles, a simplified computational model was created using a time-dependent, one-dimensional, implicit finite difference method to calculate the temperature at 20 evenly spaced nodes. The temperature profile of the tube was assumed to vary only radially, so the interior points were solved using the transient one-dimensional heat conduction equation. One dimensional convection boundaries were applied at the inner and outer walls of the tube. Boundary conditions of increasing complexity were applied, beginning with a constant temperature, natural convection condition at the outer wall and a forced convection boundary condition at the inner wall with a step change in temperature to simulate the detonation wave. Experimentally measured wall temperatures are presented and compared to computationally obtained temperature profiles. The focus is on understanding the physical reason for the behavior of the insulated tubes.
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