Relevant bibliographies by topics / In compositional fluctuations

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Academic literature on the topic 'In compositional fluctuations'

Author: Grafiati
Published: 4 June 2021
Last updated: 12 February 2022

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Journal articles on the topic "In compositional fluctuations"

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Cohen, Norman S., and Leon D. Strand. "Combustion response to compositional fluctuations." AIAA Journal 23, no. 5 (May 1985): 760–67. http://dx.doi.org/10.2514/3.8981.

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Klochikhin, A. A., V. Yu Davydov, and E. R. Seel’. "Compositional fluctuations in isotopic solid solutions." Physics of the Solid State 49, no. 1 (January 2007): 46–54. http://dx.doi.org/10.1134/s106378340701009x.

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Verwey, G. C., and M. Warner. "Compositional Fluctuations and Semisoftness in Nematic Elastomers." Macromolecules 30, no. 14 (July 1997): 4189–95. http://dx.doi.org/10.1021/ma961801i.

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Grout, R. W., N. Swaminathan, and R. S. Cant. "Effects of compositional fluctuations on premixed flames." Combustion Theory and Modelling 13, no. 5 (December 2, 2009): 823–52. http://dx.doi.org/10.1080/13647830903160291.

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Chen, Shih-Yun, In-Gann Chen, Yang-Chung Liao, and Maw-Kuen Wu. "Effect of different nanoscale RE2BaCuO5 additions on the formation of compositional fluctuation in Sm–Ba–Cu–O superconducting bulk materials." Journal of Materials Research 20, no. 2 (February 2005): 482–88. http://dx.doi.org/10.1557/jmr.2005.0055.

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This study presents the effect of different nanoscale RE211 additions—Y2BaCuO5 (nmY211), Sm2BaCuO5 (nmSm211), and Nd4Ba2Cu2O10 (nmNd422)—on the nano-scale compositional fluctuation and associated pinning mechanism of the melt-textured growth (MTG) Sm–Ba–Cu–O [SmBCO, of which the composition is Sm123 (Sm1Ba2Cu3Oy) + 25 wt% Sm211 (Sm2BaCuO5)] superconducting bulk materials. The superconductivity and microstructure results indicated that in samples with the addition of these nano-sized particles, nanoscale compositional fluctuations form during the peritectic transformation of melt-growth process, which cause Tc variation on a nanoscale and result in the formation of δTc pinning centers at high magnetic field. The compositional fluctuation regions (δTc pinning centers) are altered by the difference in peritectic temperature, the solubility in the liquid phase, and the ion radius. The direct current transport R-T properties elucidate the change of flux pinning behavior. In addition, the different influence on microstructure and superconductivity between the two methods: mixing rare-earth elements in nanoscale RE211 or in the homogeneous mixed precursor powders [e.g., (Nd, Eu, Gd)–Ba–Cu–O (NEG)] is also discussed.
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Uenoyama, Takeshi. "Optical Gain Spectra in InGaN/GaN Quantum Wells with the Compositional Fluctuations." MRS Internet Journal of Nitride Semiconductor Research 4, S1 (1999): 112–17. http://dx.doi.org/10.1557/s1092578300002313.

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The compositional fluctuations of the In content were found in InGaN/GaN quantum wells and it caused the localized states by the potential fluctuation. We have evaluated the optical gain of GaN based quantum well structures with localized states. The localized states are treated as the subband states of the quantum disk-like dots in the well. It was found that the inhomogeneous broadening played an important role in the optical gain and that it should be reduced to use the benefit of the localized states for laser oscillations.
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Portz, V., M. Schnedler, M. Duchamp, F. M. Hsiao, H. Eisele, J. F. Carlin, R. Butté, N. Grandjean, R. E. Dunin-Borkowski, and Ph Ebert. "Strain and compositional fluctuations in Al0.81In0.19N/GaN heterostructures." Applied Physics Letters 109, no. 13 (September 26, 2016): 132102. http://dx.doi.org/10.1063/1.4963184.

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PĂCURAR, Florin, Ioan ROTAR, Albert REIF, Roxana VIDICAN, Vlad STOIAN, Stefanie M. GÄRTNER, and Robert B. ALLEN. "Impact of Climate on Vegetation Change in a Mountain Grassland – Succession and Fluctuation." Notulae Botanicae Horti Agrobotanici Cluj-Napoca 42, no. 2 (December 2, 2014): 347–56. http://dx.doi.org/10.15835/nbha4229578.

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Traditionally managed Central European mountain grasslands have high nature conservation value because of their high species diversity. Whether these grasslands and their diversity can be preserved will depend on many factors, including how plant species composition responds to changes in climate conditions. To differentiate between fluctuations and directional succession in the herbaceous layer composition of a Romanian Festuca rubra L. and Agrostis capillaris L. grassland in Apuseni and whether any compositional changes can be related to climate. The vegetation of permanent plots was recorded annually between 2004 and 2012. Temperature and precipitation were measured by an automatic weather station at the study site. Cluster analysis, Indicator Species Analysis and the co-dominance ratio between F. rubra L.- A. capillaris were analysed. The compositional data was related to the climate variables. Thresholds of relevant climate variables differentiating between clusters of plots with similar vegetation composition were determined using classification tree methods. The vegetation composition in our plots within the years 2004, 2005 and 2008 were different from each other. From 2004 to 2006 directional succession could be identified; however the major patterns to emerge were fluctuations which occurred over the whole study period. Compositional shifts included A. capillaris L. and F. rubra L exchanging co-dominance with each other. The most important variables differentiating clusters were temperature during the dormant and vegetation periods and water balance during the vegetation period. It can be concluded that compositional shifts among years were largely a consequence of year to year climatic fluctuations; however, there is some evidence for a directional shift during the early years of the study./span>
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Newcomb, S. B., and W. M. Stobbs. "Compositional fluctuations in scaling processes: their characterisation and relevance." Materials Science and Technology 4, no. 5 (May 1988): 384–90. http://dx.doi.org/10.1179/mst.1988.4.5.384.

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Li, S., L. Charles Dickinson, and James C. W. Chien. "Local compositional fluctuations in PPO/HIPSand PPO/SBS blends." Journal of Polymer Science Part B: Polymer Physics 32, no. 4 (March 1994): 607–13. http://dx.doi.org/10.1002/polb.1994.090320402.

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Dissertations / Theses on the topic "In compositional fluctuations"

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Flanigan, Sean Gerard. "From Deux Danses to Fluctuations: Compositional components and innovations in two solo trombone works of Jean-Michel Defaye." Thesis, connect to online resource, 2006. http://www.unt.edu/etd/all/Aug2006/flanigan%5Fsean%5Fgerard/index.htm.

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Thesis (D.M.A.)--University of North Texas, 2006.
System requirements: Adobe Acrobat Reader. Accompanied by 4 recitals, recorded June 28, 1999, Jan. 24, 2000, Jan. 29, 2001, and Apr. 10, 2006. Includes bibliographical references and discography (p. 66-70).
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Belloeil, Matthias. "Croissance par épitaxie par jets moléculaires et caractérisation optique d'hétérostructures de nanofils GaN/AlGaN émettant dans l'ultraviolet." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY021/document.

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Dans des conditions de croissance spécifiques, des sections nanofilaires d’AlGaN peuvent croître en épitaxie sur des bases nanofilaires de GaN. De telles croissances, effectuées par épitaxie par jets moléculaires dans le cadre dans le cas présent, permettent la caractérisation ultérieure de petits volumes d’AlGaN exempt de défauts étendus communément observés dans les couches planaires. Cette absence de défauts rend ces fils prometteurs pour les dispositifs optoélectroniques émettant dans l’ultraviolet. Cependant, la réalisation de tels composants nécessite de mieux comprendre les propriétés fondamentales des fils.La question des inhomogénéités d’alliage à l’échelle nanométrique reste notamment à éclaircir. Afin d’y voir plus clair, ces dernières ont été dans un premier temps étudiées dans cette thèse. Pour nos expériences, des nanofils d’AlGaN non-intentionnellement dopés (NID) ont été crûs dans des conditions variées afin d’ajuster potentiellement les fluctuations de composition de l’alliage et ainsi sonder éventuellement des centres de localisation de porteurs de taille et composition différentes. Il a premièrement été observé au moyen de méthodes de caractérisation structurale que la longueur des sections plus riches Al qui nucléent préférentiellement au sommet des fils de GaN peut être ajustée en variant les paramètres cinétiques de croissance, mettant en lumière un mécanisme de croissance gouverné par la cinétique. Des études optiques ont ensuite démontré que les fluctuations de composition induisent de la localisation et présentent un comportement de type boîte quantique. Ce dernier a été observé quel que soit les conditions de croissance explorées dans ce travail. Il est ensuite démontré que les régions plus riches Ga spontanément formés durant la synthèse de l’AlGaN partagent des propriétés µ-optiques similaires sur une plage de longueur d’onde d’émission donnée, pour toutes les conditions de croissance utilisées dans cette étude. De telles régions, émettrices de photons uniques, sont présentes à très petite échelle, puisque elles ont été également mises en évidence dans des nanodisques quantiques d’AlGaN très fins.En outre, le dopage des nanofils d’AlGaN, surtout de type p, est loin d’être totalement compris. En particulier, En particulier, le problème de l’incorporation ainsi que de l’activation optique et électrique dans les fils demeure nébuleux. Cette question a été étudiée pour des jonctions pn nanofilaires d’AlGaN dopées avec des atomes Mg et Si. Premièrement, des signatures propres à l’incorporation des dopants dans les nanofils ont été mises en exergue au travers de techniques de caractérisation structurale, avant que des jonctions pn AlGaN soient mises en évidence électriquement. De plus, des analyses optiques ont mis en lumière des dopants de type n et p optiquement actifs. Néanmoins, les dopants Mg ne sont que partiellement actifs électriquement en raison de la passivation par l’hydrogène mise en évidence par l’observation de complexes Mg-H. Pour résoudre ce problème, des recuits post-croissance ont été effectués. En parallèle, des jonctions pn nanofilaires d’AlN ont été préliminairement examinées et présentent des caractéristiques morphologiques intéressantes. En effet, des creux profonds ont été observés dans les fils et associés au dopage Mg effectué à basse température de croissance. La morphologie des fils peut être ajustée en jouant sur les paramètres cinétiques de croissance et sur l’effet surfactant des atomes Mg. En augmentant la température, les creux disparaissent tandis que la forme du sommet des fils, usuellement hexagonale, change pour devenir « étoilée », mettant en exergue des conditions de croissance très éloignées de l’équilibre thermodynamique. L’activation électrique des dopants n’a pas été observée jusqu’à présent dans ces jonctions pn d’AlN
Using specific growth conditions, AlGaN nanowire (NW) sections can be grown in epitaxy on top of GaN NW templates. Such NW growth, performed by plasma-assisted molecular beam epitaxy in the present case, allows the subsequent characterization of very small volume of material free of extended defects commonly observed in planar structures. This absence of defects makes these NWs very promising for optoelectronic devices operating in the ultraviolet. However, achieving such devices requires a better understanding of the NW fundamental properties.The issue of alloy inhomogeneity at nanoscale has notably remained obscure so far. In order to make it clearer, the latter has been first investigated in the present work, especially through optical characterization. For our experiments, non-intentionally doped (NID) AlGaN NWs have been grown in various conditions in order to potentially tune the compositional fluctuations within the AlGaN alloy and therefore possibly probe for carrier localization centers of different size and Al composition. It has been firstly observed through structural characterization that the length of Al-rich sections preferentially nucleating on top of GaN NWs can be tuned by varying the growth kinetical parameters, emphasizing a growth mechanism governed by kinetics. Optical studies have then evidenced that compositional fluctuations induce carrier localization and exhibit a quantum dot-like behavior. The latter has been observed whatever the growth conditions explored in this work. Our results are consistent with the spontaneous formation during growth of tiny Ga-richer regions shown to share similar micro-optical features over a given emission wavelength range for all investigated growth conditions. Such regions exhibiting the single-photon emission character are present at very small scale, as signs of their existence have been also evidenced in thin NID AlGaN quantum disks.In addition, doping in Al(Ga)N NW, especially p-type, is far from being fully comprehended. In particular, the issue of dopant incorporation as well as optical and electrical activation in such NWs remains unclear. The latter has been examined in Al(Ga)N NW pn junctions doped with Mg and Si atoms. First, signatures specific to dopant incorporation in NWs have been highlighted through structural characterization, before evidencing AlGaN pn junctions electrically. Moreover, optical analysis have exhibited optically active both dopant types. Nonetheless, Mg dopants are but partially active electrically due to passivation by hydrogen emphasized by the observation of Mg-H complexes. To cope with the latter issue, post-growth annealing experiments have been attempted. Concomitantly, AlN NW pn junctions have been also preliminarily investigated and present interesting morphological features. Indeed, deep hollows have been observed in NWs and associated with Mg doping carried out at low growth temperature. The NW morphology can be tuned by varying growth kinetical parameters and by using the surfactant effect of Mg atoms. When increasing growth temperature, these hollows disappear, while the NW top shape has been observed to switch from hexagonal to star-like, emphasizing growth conditions very far from thermodynamical equilibrium. Electrical activation of dopants has not been evidenced so far in AlN NW pn junctions
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Wozniak, Trevor Mathew. "Four Fluctuations for Chamber Ensemble or Chamber Orchestra." Kent State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=kent1291050505.

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Mutta, Geeta Rani. "Propriétés structurales, optiques et électroniques des couches d’InN et hétérostructures riches en indium pour applications optoélectroniques." Caen, 2012. http://www.theses.fr/2012CAEN2013.

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Les semi-conducteurs nitrures (AlN, GaN, InN) focalisent une activité de recherche intense en raison de nombreuses applications comme les diodes électroluminescentes, les composants de puissance ou hyperfréquence. Dans cette recherche, nous avons abordé le travail sous deux angles: a) la conduction électrique dans les couches d'InN produites par croissance épitaxiale aux jets moléculaires assistée par plasma (PAMBE) et une recherche sur l'origine de la forte émission bleue dans les puits de quantiques d'InGaN/GaN. L'accumulation d'électron en surface dans les couches d'InN constitue une limitation importante pour la fabrication de composants. Au cours de ce travail, nous avons exploré l'utilisation des mesures de bruit de basse fréquence sur les couches d'InN et pu accéder à leur conductivité électrique en volume. L'étude des puits quantiques d'InGaN/GaN, obtenue par croissance épitaxiale aux jets moléculaires (MBE) ou épitaxie en phase vapeurs aux organométalliques (MOVPE) , a été effectuée par analyses de la microstructure par microscopie électronique en transmission (MET, HRTEM et STEM) en corrélation avec les propriétés optiques d'un grand nombre d'échantillons provenant de conditions de croissance différentes. Ce travail nous a permis d'acquérir une vision plus critique du rôle des conditions de fabrication et des paramètres comme la morphologie, les fluctuations de composition et la présence des défauts en V sur les explications actuellement avancées pour la forte efficacité d'émission dans les puits quantiques d' InGaN/GaN
The nitride semiconductors (AlN, GaN, InN) are subject to a large research effort due to their numerous applications, such as light emitting diodes, high power and high frequency components. Following the trend, the aim of this dissertation has been twofold: first, we have probed the bulk electrical conduction in InN layers, second, we investigated the origin of the high emission efficiency in InGaN/GaN Quantum Wells (QWs). The surface electron accumulation in InN layers is still an important limitation to device applications. W have explored this point using low frequency noise measurements on Plasma Assisted Molecular Beam Epitaxy (PAMBE) InN layers and we demonstrated that the bulk electrical conductivity of InN can be accessed. The investigation of quantum wells produced by molecular beam epitaxy (MBE) or matalorganic vapour phase epitaxy (MOVPE), has been carried out through microstructural analyses by transmission electron microscopy techniques(TEM, HRTEM, STEM) in correlation with optica properties on a large number of samples grown in different growth conditions. This experimental work has allowed us to obtain a critical view on the role of the growth conditions and such parameters as the well morphology, composition fluctuations, as well as the V shaped defects on the current explanations of high emission efficiency in InGaN/GaN QWs
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CASTRO, MARY LUCIA DIAZ. "INTRINSIC FLUCTUATIONS OF EXTENSIVE AIR SHOWERS AND THE CHEMICAL COMPOSITION OF ULTRA HIGH ENERGY COSMIC RAYS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=19921@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
O Observatório Pierre Auger é um detector de raios cósmicos ultra-energéticos (E maior ou igual 1018 eV) com características híbridas, que combinam detectores de superfície e de fluorescência. A determinação da composição química primária destes raios cósmicos é um dos seus principais objetivos. Há indícios de que os primários dos raios cósmicos com E maior que 1018.5 eV tem massa maior, conclusão baseada nos resultados recentes sobre a evolução dos chuveiros atmosféricos extensos (cascatas de partículas formadas quando da colisão do raio cósmico primário no topo da atmosfera com moléculas de N2 ou O2). Encontrar parâmetros, que caracterizam o chuveiro, no processo de sua reconstrução e que forneçam informações associadas a este resultado, são essenciais para validar esta conclusão. Nesta tese estuda-se a evolução como função da energia, de parâmetros que caracterizam os chuveiros, que sejam sensíveis à sua composição primária. Mais especificamente aqueles determinados pelo detector de superfície, pois há uma estatística de chuveiros detectados significativamente maior. Damos especial atenção às flutuações intrínsecas – chuveiro-a-chuveiro – do parâmetro de inclinação (beta) da Função de Distribuição Lateral, que descreve a variação da densidade de partículas ao longo da direção perpendicular ao eixo do chuveiro, como função da distância a esse eixo. Os resultados indicam que a flutuação intrínseca em beta, para eventos inclinados (45-60 graus) com E maior que 1018.5 eV, possui uma tendência de diminuição com a energia até valores em torno de 1019.8 eV. Este resultado é consistente com o encontrado anteriormente em análises de composição química sobre a evolução com a energia da profundidade de máximo (Xmax) dos chuveiros atmosféricos extensosmedida pelos detectores do Auger em modo híbrido, em que em energias acima de 1018.5 eV, observase que os chuveiros tendem a atingir seu máximo numa região mais bem definida da atmosfera, levando, por conseguinte, a flutuações menores no sinal no solo.
The Pierre Auger Observatory is an ultra high energy cosmic ray detector (E more than or equal as 1018 eV) which has hybrid characteristics combining surface and fluorescence detectors. Determining the cosmic rays chemical composition is one of its most important challenges. There are evidences that cosmic ray primaries with energy above 1018.5 eV are heavy and this conclusion is based on recent results on the evolution of extensive air showers (cascades of particles formed by the collision of primary cosmic rays in the top of the atmosphere with nitrogen and oxygen molecules). Therefore, it is mandatory to find additional parameters supporting that conclusion. In this thesis, the evolution with energy of parameters characterizing the shower and with sensitivity to chemical composition are studied. More specifically, parameters determined by the surface detector are analyzed due to the high statistics in this operation mode. Special attention is given to the instrinsic - shower to shower - fluctuations of the slope parameter (beta) of the Lateral Distribution Function which describes the particles density variation in the plane perpendicular to the shower axis as a function of distance to that axis. The results show that the intrinsic fluctuation of Beta, for inclined showers (45-60 degrees) with energy above 1018.5 eV, where the detector resolution is small compared to the total fluctuation, has a trend to decrease with energy up to 1019.6 eV. This result is consistent with recent results on the energy evolution of the depth of shower maxima (Xmax) of extensive air showers, where above 1018.5 eV, the distributions of Xmax show less fluctuations, leading, in turn, to less fluctuations on the ground level.
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Mayhall, Ronald Bruce. "Tempo fluctuation in the Romantic Era as revealed by nineteenth-century sources and applied to selected choral compositions /." Full-text version available from OU Domain via ProQuest Digital Dissertations, 1990.

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Zhang, Xin. "Growth and characterization of GaN/lnGaN nanowire heterostructures." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY107.

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Les nanostructures de nitrures d’éléments III sont considérées comme des candidats prometteurs visant à la réalisation de divers dispositifs innovants. Depuis quelques années, l'intérêt croissant des nano-LEDs basés sur l’InGaN a été relevé dans le domaine de l'éclairage et de l'affichage. Ce travail de thèse porte sur la croissance par épitaxie par jets moléculaires assistée plasma (PA-MBE) et sur la caractérisation d'hétérostructures InGaN/GaN à base de nanofils.Tout d'abord, un modèle de croissance cinétique de nanofils de nitrures d’éléments III a été établi, en vue d'une analyse en profondeur et d'un meilleur contrôle des processus cinétiques atomiques impliqués dans la croissance MBE. Ce travail de modélisation construit la base théorique et guide l'interprétation expérimentale dans cette thèse.Ensuite, les propriétés morphologiques, structurelles, compositionnelles et optiques des hétérostructures de nanofils GaN/InGaN/GaN axiaux ont été étudiées à nano-échelle par une combinaison de microscopie électronique (SEM / STEM / TEM), photoluminescence (PL), nano-cathodoluminescence (nano-CL), spectroscopie de rayons-X à énergie dispersive (EDX). Sur la base des résultats expérimentaux, nous avons obtenu une description statistique du paysage morphologique pour tous les NWs InGaN/GaN sous différentes conditions thermodynamiques et de flux atomiques. De plus, la corrélation entre les caractéristiques morphologiques & compositionnelles et les propriétés électroniques & optiques des NWs InGaN/GaN a été établie.En outre, divers types de superstructures InGaN à base de nanofils ont été étudiés. On constate que tant le taux de croissance axiale que la composition réelle d’Indium vont diminuer dans le cas de l'excès d'Indium, en raison de l'effet surfactant de l’Indium et d'un flux effectif d’azote réduit. En même temps, un élargissement spectaculaire des sections de l'InGaN a été observé sous des conditions riches en azote, suggérant que la condition riche en métal n'est pas nécessaire pour l'élargissement de l'InGaN. En conséquence, nous proposons le mécanisme de la croissance d’InGaN, pour lequel la croissance axiale est un processus cinétique déterminé par le flux et l'élargissement latéral est principalement induit par la contrainte.Enfin, nous avons étudié l'influence du processus de recuit pour l'efficacité de la luminescence et proposé nos recettes de croissance de plaques LEDs, visant à aborder la fabrication de plaques LED développées par MBE
Group-III-nitride nanostructures are considered as promising candidates aiming at the realization of various innovative devices, including fields from electronics, photonics, to biochemistry and energy. Since recent years, a growing interest of InGaN-based nano-LEDs has been raised in the field of lighting and display. This PhD work focuses on the growth by plasma-assisted molecular beam epitaxy and on the characterization of nanowire-based InGaN/GaN heterostructures.Firstly, a kinetic growth model of III-nitride nanowires has been established, aiming at an in-depth analysis and a better control of atomically kinetic processes involved in MBE growth. This modeling work constructs the theoretical basis and guides the experimental interpretation in this thesis.Then, the morphological, inner-structural, compositional and optical properties of axial GaN/InGaN/GaN nanowire heterostructures have been investigated at nano-scale by a combination of electron microscopy (SEM/STEM/TEM), photoluminescence (PL), nano-cathodoluminescence (nano-CL), energy-dispersive X-ray spectroscopy (EDX). On the basis of experimental results, we have achieved a statistical description of morphological landscape for all InGaN/GaN NWs under different thermodynamic and atomic fluxes conditions. Meanwhile, the correlation between the morphological & compositional features and the electronic & optical properties of InGaN/GaN NWs has been established.Furthermore, various types of NW-based InGaN superstructures have been grown and investigated. It is found that both axial growth rate and real In composition will decrease in the case of Indium excess, due to In surfactant effect and a reduced effective nitrogen flux. Meanwhile, a dramatic widening of InGaN sections has been observed under N-rich condition, suggesting the metal-rich condition is not necessary for the InGaN enlargement. Accordingly, we propose the driving mechanism of InGaN growth, for which the axial growth is a flux-determined kinetic process and the lateral widening is mainly strain-induced.Finally, we have investigated the influence of post-growth annealing process for the luminescence efficiency and proposed our growth recipes of LED plates, aiming at approaching the fabrication of MBE-grown LED plates
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Vilalta-Clemente, Arantxa. "Structure des Couches d'InN et d'alliages (In,Al)N." Phd thesis, Université de Caen, 2012. http://tel.archives-ouvertes.fr/tel-00779488.

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En raison de leurs applications prometteuses dans les domaines de l'optoélectronique et de l'électronique, les semiconducteurs III-V à base d'azote: les nitrures (AlN, GaN, InN) et leurs alliages (InAlN, InGaN, AlGaN), font l'objet, depuis les années 1990, d'une activité intense en recherche et développement. Dans ce travail, nous avons étudié les propriétés structurales des couches d'InN et de l'alliage InAlN dans les hétérostructures InAlN/AlN/GaN et InAlN/GaN en combinant les techniques AFM, IBA, DRXHR, Raman et MET. L'étude des couches d'InN a été menée par DRX afin de déterminer la contrainte résiduelle, et on a cherché à faire une corrélation avec la morphologie des surfaces par AFM. Les contraintes résiduelles obtenues par DRX ont été comparées aux résultats de spectroscopie Raman, et on a pu montrer que toutes les couches avaient une contrainte résiduelle qui n'est pas purement bi-axiale. Les hétérostructures InAlN pour transistors à haute mobilité électronique (HEMTs) sont des couches ultraminces de quelques monocouches atomiques à plusieurs dizaines de nanomètres d'épaisseur. De plus, leur structure peut être assez complexe dans le but d'optimiser le gaz d'électrons généré dans le canal du transistor. Dans l'idéal, on utilise une concentration en indium autour de 17%, qui est celle de l'accord de paramètres cristallins avec le GaN. Nos travaux ont mis en évidence qu'il n'est pas facile de contrôler la composition locale; en effet la structure et morphologie des couches sont très sensibles aux conditions de croissance.
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Mutta, G. R. "Propriétés structurales, optiques et électroniques des couches d'InN et hétérostructures riches en indium pour applications optoélectroniques." Phd thesis, Université de Caen, 2012. http://tel.archives-ouvertes.fr/tel-00779495.

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Les semi-conducteurs nitrures (AlN, GaN, InN) focalisent une activité de recherche intense en raison de nombreuses applications comme les diodes électroluminescentes, les composants de puissance ou hyperfréquence. Dans cette recherche, nous avons abordé le travail sous deux angles: a) la conduction électrique dans les couches d'InN produites par croissance épitaxiale aux jets moléculaires assistée par plasma (PAMBE) et une recherche sur l'origine de la forte émission bleue dans les puits de quantiques d'InGaN/GaN. L'accumulation d'électron en surface dans les couches d'InN constitue une limitation importante pour la fabrication de composants. Au cours de ce travail, nous avons exploré l'utilisation des mesures de bruit de basse fréquence sur les couches d'InN et pu accéder à leur conductivité électrique en volume. L'étude des puits quantiques d'InGaN/GaN, obtenue par croissance épitaxiale aux jets moléculaires (MBE) ou épitaxie en phase vapeurs aux organométalliques (MOVPE) , a été effectuée par analyses de la microstructure par microscopie électronique en transmission (MET, HRTEM et STEM) en corrélation avec les propriétés optiques d'un grand nombre d'échantillons provenant de conditions de croissance différentes. Ce travail nous a permis d'acquérir une vision plus critique du rôle des conditions de fabrication et des paramètres comme la morphologie, les fluctuations de composition et la présence des défauts en V sur les explications actuellement avancées pour la forte efficacité d'émission dans les puits quantiques d' InGaN/GaN.
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Cheaito, Bassam. "Contribution à l'étude de la supraconductivité anormale du composé EuMo6S8." Grenoble 1, 1986. http://www.theses.fr/1986GRE10100.

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Etude de monocristaux de eumo::(6)s::(8) et d'echantillons frittes de yb::(1,2-x)eu::(x)mo::(6)s::(8) basee sur des mesures de transport sous pression et sous champ magnetique, des mesures de la susceptibilite magnetique et des mesures rpe; mise au point d'un dispositif automatise de mesures de transport. Correlations entre la temperature de transition structurale, la remontee de la resistivite a basse temperature et la transition supraconductrice sous pression; effets de la composition des echantillons frittes. Mise en evidence d'une valeur tres elevee du coefficient de chaleur massique electronique. Discussion des proprietes anormales dans le cadre d'un modele de melange de phases triclinique et rhomboedrique et d'un modele de supraconductivite propre
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Books on the topic "In compositional fluctuations"

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Renard, Maurice. Geochimie des Carbonates Pelagiques: Mise en evidence des fluctuations de la composition des eaux oceaniques depuis 140 ma essai de chimiostratigraphie. Orlean,France: Recherches Geologiques et minieres, 1985.

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Shrock, Dennis. Johannes Brahms – Ein deutsches Requiem. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780190469023.003.0008.

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Chapter 8 begins with historical precedents, including Brahms’s appointments as a choral conductor during his early professional life, his interest in and performance of works by J. S. Bach, and his association with Robert Schumann—of short duration but of profound influence. Substantial discussion is also given to the texts about life suffering that Brahms chose for most of his sacred choral compositions. The Requiem is discussed in terms of its long gestation, unification through use of musical motifs, and balanced and mirror structures. Performance practice issues include timbre and vibrato, metric accentuation, disposition of performers on stage, and tempo fluctuation.
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Higdon, Dave, Katrin Heitmann, Charles Nakhleh, and Salman Habib. Combining simulations and physical observations to estimate cosmological parameters. Edited by Anthony O'Hagan and Mike West. Oxford University Press, 2018. http://dx.doi.org/10.1093/oxfordhb/9780198703174.013.26.

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This article focuses on the use of a Bayesian approach that combines simulations and physical observations to estimate cosmological parameters. It begins with an overview of the Λ-cold dark matter (CDM) model, the simplest cosmological model in agreement with the cosmic microwave background (CMB) and largescale structure analysis. The CDM model is determined by a small number of parameters which control the composition, expansion and fluctuations of the universe. The present study aims to learn about the values of these parameters using measurements from the Sloan Digital Sky Survey (SDSS). Computationally intensive simulation results are combined with measurements from the SDSS to infer about a subset of the parameters that control the CDM model. The article also describes a statistical framework used to determine a posterior distribution for these cosmological parameters and concludes by showing how it can be extended to include data from diverse data sources.
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Book chapters on the topic "In compositional fluctuations"

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Holzmann, Roswitha. "Seasonal fluctuations in the diversity and compositional stability of phytoplankton communities in small lakes in upper Bavaria." In Intermediate Disturbance Hypothesis in Phytoplankton Ecology, 101–9. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-1919-3_10.

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Lutsenko, G. V., and Andriy Gusak. "Composition Fluctuations in the Ostwald Ripening." In Defect and Diffusion Forum, 187–92. Stafa: Trans Tech Publications Ltd., 2008. http://dx.doi.org/10.4028/3-908451-55-8.187.

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Chrissopoulou, K., F. Rittig, and G. Fytas. "Long wavelength composition fluctuations in diblock copolymers." In Molecular Interactions and Time-Space Organization in Macromolecular Systems, 109–13. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-60226-9_12.

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Teubner, Max. "Composition Fluctuations and Phase Diagrams for Ternary Mixtures." In Structure and Dynamics of Strongly Interacting Colloids and Supramolecular Aggregates in Solution, 579–85. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2540-6_29.

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Krivolaz, Mikhail A. "Fluctuation Waves of the Composition and Order Parameters." In Diffuse Scattering of X-Rays and Neutrons by Fluctuations, 1–50. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-642-78765-2_1.

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Fontvieille, Louis. "The Movement of Capital’s Composition : Long Term Fluctuations and Trend." In Lecture Notes in Economics and Mathematical Systems, 177–205. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-48360-8_11.

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Krivoglaz, Mikhail A. "Fluctuations of Composition and Order Parameters in Undistorted Solid Solutions." In Theory of X-Ray and Thermal Neutron Scattering by Real Crystals, 3–60. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4899-5582-1_1.

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Salemink, H. W. M., M. B. Johnson, U. Maier, P. Koenraad, and O. Albrektsen. "Epitaxial Interfaces of III-V Heterostructures: Atomic Resolution, Composition Fluctuations and Doping." In Semiconductor Interfaces at the Sub-Nanometer Scale, 151–60. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-2034-0_16.

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Correia, M. R. "Strain and indium compositions fluctuations in InGaN/GaN wurtzite epitaxial films studied by Raman Spectroscopy." In Spectroscopy of Systems with Spatially Confined Structures, 712. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0287-5_39.

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Navarro, Enrique, and Juan I. P. Iglesias. "Infaunal Filter-Feeding Bivalves and the Physiological Response to Short-Term Fluctuations in Food Availability and Composition." In Bivalve Filter Feeders, 25–56. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-78353-1_2.

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Conference papers on the topic "In compositional fluctuations"

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Wongratanaphisan, Duangmanee, Theerapong Santhaveesuk, and Supab Choopun. "Raman spectroscopy of compositional fluctuations in spinel Zn2TiO4 nanostructures." In 2010 IEEE 3rd International Nanoelectronics Conference (INEC). IEEE, 2010. http://dx.doi.org/10.1109/inec.2010.5424666.

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Stevens, M. "Electrostatic Fields and Compositional Fluctuations in InGaN Quantum Wells." In PHYSICS OF SEMICONDUCTORS: 27th International Conference on the Physics of Semiconductors - ICPS-27. AIP, 2005. http://dx.doi.org/10.1063/1.1994069.

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Yen-Cheng Lu, Damdin Tuvshin, Yung-Chen Cheng, and Chih-Chung Yang. "Monte Carlo simulation of carrier dynamics in semiconductors with compositional fluctuations." In 2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference. IEEE, 2006. http://dx.doi.org/10.1109/cleo.2006.4628595.

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Sun, Xiao. "Broadband gain incorporating N compositional fluctuations for a GaInNAs semiconductor optical amplifier." In Asia Communications and Photonics Conference. Washington, D.C.: OSA, 2014. http://dx.doi.org/10.1364/acpc.2014.ath3a.15.

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Sun, X., N. Vogiatzis, and J. M. Rorison. "Modelling dilute nitride 1.3 μm quantum well lasers: Incorporation of N compositional fluctuations." In 2013 Conference on Lasers & Electro-Optics Europe & International Quantum Electronics Conference CLEO EUROPE/IQEC. IEEE, 2013. http://dx.doi.org/10.1109/cleoe-iqec.2013.6800742.

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Giusti, Andrea, Luca Magri, and Marco Zedda. "Flow Inhomogeneities in a Realistic Aeronautical Gas-Turbine Combustor: Formation, Evolution and Indirect Noise." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76436.

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Indirect noise generated by the acceleration of combustion inhomogeneities is an important aspect in the design of aeroengines because of its impact on the overall noise emitted by an aircraft and the possible contribution to combustion instabilities. In this study, a realistic rich-quench-lean combustor is numerically investigated, with the objective of quantitatively analyzing the formation and evolution of flow inhomogeneities and determine the level of indirect combustion noise in the nozzle guide vane (NGV). Both entropy and compositional noise are calculated in this work. A high-fidelity numerical simulation of the combustion chamber, based on the Large-Eddy Simulation (LES) approach with the Conditional Moment Closure (CMC) combustion model, is performed. The contributions of the different air streams to the formation of flow inhomogeneities are pinned down and separated with seven dedicated passive scalars. LES-CMC results are then used to determine the acoustic sources to feed an NGV aeroacoustic model, which outputs the noise generated by entropy and compositional inhomogeneities. Results show that non-negligible fluctuations of temperature and composition reach the combustor’s exit. Combustion inhomogeneities originate both from finite-rate chemistry effects and incomplete mixing. In particular, the role of mixing with dilution and liner air flows on the level of combustion inhomogeneities at the combustor’s exit is highlighted. The species that most contribute to indirect noise are identified and the transfer functions of a realistic NGV are computed. The noise level indicates that indirect noise generated by temperature fluctuations is larger that the indirect noise generated by compositional inhomogeneities, although the latter is not negligible and is expected to become louder in supersonic nozzles. It is also shown that relatively small fluctuations of the local flame structure can lead to significant variations of the nozzle transfer function, whose gain increases with the Mach number. This highlights the necessity of an on-line solution of the local flame structure, which is performed in this paper by CMC, for an accurate prediction of the level of compositional noise. This study opens new possibilities for the identification, separation and calculation of the sources of indirect combustion noise in realistic aeronautical gas turbines.
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Sun, Xiao, and Qingjiang Chang. "Ultra-broadband GaInNAs semiconductor optical amplifier incorporating N compositional fluctuations for the next generation passive optical network." In SPIE OPTO, edited by Benjamin B. Dingel and Katsutoshi Tsukamoto. SPIE, 2015. http://dx.doi.org/10.1117/12.2077686.

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Rolland, Erwan O., Francesca De Domenico, and Simone Hochgreb. "Direct and Indirect Noise Generated by Injected Entropic and Compositional Inhomogeneities." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-64428.

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Flow disturbances are generated inside a duct via pulsed injection of helium into a flow of air. This leads to the generation of an acoustic pulse (direct noise), as well as the production of entropic and compositional inhomogeneities which are convected with the mean flow. As these inhomogeneities are convected through a choked nozzle, they generate indirect noise. The resulting acoustic pressure fluctuations are measured experimentally using pressure transducers upstream of the nozzle. Insight obtained from theoretical models and a time-delay analysis can be used to isolate and extract the contributions of direct and indirect noise in the experimental signal. These results are directly compared to existing one-dimensional direct and indirect noise models. The experimental measurement of indirect noise is found to be in good agreement with the theoretical models for entropy noise and compositional noise for a compact one-dimensional isentropic nozzle.
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O’Brien, Jeffrey D., and Matthias Ihme. "Species Dependency of the Compositional Indirect Noise Mechanism." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63076.

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Indirect combustion noise is a growing concern for aviation engine designers. It is typically associated with the distortion of “hot spots” (entropy structures) and vortical structures that generate excess noise as they are convected by an accelerating mean flow. Recently, it has been shown theoretically that fluctuations in a gas’s chemical composition can act as an additional source of indirect noise in aviation engines. This work examines this composition noise mechanism, focusing on the underlying chemical effects that drive this source of indirect noise. Since the mechanism has yet to be confirmed experimentally, this paper begins by applying the theory to inert mixtures of noble gases and air, in an attempt to guide experimentalists by identifying the set of operating conditions that will produce the strongest acoustic response. Turning from non-reacting to reacting flows, the paper next examines the sensitivity of the compositional noise mechanism to fuel type, testing several common fuels. It is found that, while there is a substantial difference between hydrogen and hydrocarbon fuels, overall noise levels vary only slightly between different hydrocarbon fuels. Additionally, there appears to be a common underlying structure to the response of a product-gas mixture generated by burning a fuel, which is explained through linearized theory and confirmed with numerical results. Lastly, the physics of composition noise is examined at the species-specific level, attempting to provide a link between individual combustion products and changes in a mixture’s propensity to generate indirect noise. The sensitivity of individual species can be explained by a combination of differences between the species and mixture’s Gibbs free energy and strong gradients in product gas concentration with mixture fraction. However, by analyzing the species dependency of combustion products at several different mean mixture fractions, it is found that no single species dominates the noise generation over the combustor’s entire range, but rather the most acoustically active species varies strongly with local stoichiometry.
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Sun, Xiao, Nikolaos Vogiatzis, and Judy M. Rorison. "Theoretical study of dilute nitride 1.3 µm quantum well semiconductor lasers for short pulse generation: Effect of incorporation of N compositional fluctuations." In 2013 15th International Conference on Transparent Optical Networks (ICTON). IEEE, 2013. http://dx.doi.org/10.1109/icton.2013.6602762.

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Reports on the topic "In compositional fluctuations"

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Havrlant, David, and Abdulelah Darandary. Economic Diversification under Saudi Vision 2030. King Abdullah Petroleum Studies and Research Center, April 2021. http://dx.doi.org/10.30573/ks--2021-dp06.

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The last decade has brought a row of substantial changes that have profound implications for the traditional hydrocarbon resource-rich economies. Economic conditions may change radically either throughout a decade or within months. The question is whether there is no other option for a hydrocarbon resource-rich economy than to be held hostage to the fluctuations in global oil prices. The general answer to a changing environment is: Adapt! From the macroeconomic perspective, this means diversifying the economy to broaden the income base and significantly reduce the dependence on oil revenues. The Saudi Vision 2030 represents a complex plan for substantial socioeconomic adjustments that are about to move the economy toward a more diversified and sustainable one. This discussion paper examines the preferred diversification paths for the Saudi economy in more detail, with a focus on the foreseen adjustments in the sectoral composition of the economy along with broader macroeconomic shifts. The evaluation of the foreseen diversification impacts is based on the updated Vision 2030 Input-Output Table that maps the changing structure of the Saudi economy over the coming decade. We discuss the assumed expansion of the diversification frontrunners, their changing contribution to the overall economic activity and identify the preferred diversification paths for the Saudi economy. The advances in economic diversification are measured by applying the Shannon-Weaver index to sectoral GDP and household income. The expected sectoral changes are wide-reaching, so the basic macroeconomic relations are also subject to adjustments. We also conduct a sensitivity analysis to examine the effects of the foreseen diversification on the resilience of the Saudi economy to external shocks.
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