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Relevant bibliographies by topics / Phase isotrope

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Academic literature on the topic 'Phase isotrope'

Author: Grafiati

Published: 4 June 2021

Last updated: 2 February 2022

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Journal articles on the topic "Phase isotrope"

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Pelzl, Gerhard. "Umwandlung einer nematischen in die isotrope Phase durch photochemische Isomerisierung." Zeitschrift für Chemie 17, no. 8 (September 1, 2010): 294–95. http://dx.doi.org/10.1002/zfch.19770170809.

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Zou, Peng, and Jiubing Cheng. "Three-dimensional passive-source anisotropic reverse time migration for imaging lithospheric discontinuities." Geophysical Journal International 226, no. 3 (June 3, 2021): 2103–15. http://dx.doi.org/10.1093/gji/ggab201.

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SUMMARY The scattered teleseismic body waves have been used intensively to characterize the receiver-side lithospheric structures. The routinely used ray-theory-based methods have limitations to image complex structures and tackle strong heterogeneities. The newly developed wave-equation based, passive-source reverse time migration (RTM) approach can overcome such limitations. To date, passive-source RTM has been developed only for isotropic media. However, at least to the first-order, most lithospheric structures possess effective transverse isotropy with spatially variable symmetry directions. It is important to know the magnitudes of imaging errors that may be introduced by passive-source RTM when seismic anisotropy is treated in an incorrect way. In this paper, we investigate the influence of elastic anisotropy on teleseismic P-to-S conversions at the lithospheric discontinuities and explain why an isotropic RTM may fail to focus the converted wavefields from the perspective of relative arrival time variations with backazimuth and shear wave splitting. Accordingly, we extend the passive-source RTM approach for imaging 3-D lithospheric targets possessing transverse isotropy from the following two aspects: First, the teleseismic recordings with direct P and converted S phases are reverse-time extrapolated using rotated staggered grid (RSG) pseudospectral method, which can tackle strong heterogeneity and transverse isotropies with symmetry axes in arbitrary direction; Secondly, the backward elastic wavefields are efficiently decomposed into vector anisotropic P and S modes to support accurate imaging.

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Chen, Shi-Lin, Zhi-Cheng Ma, Chang-Ling Fan, Yu-Lin Liang, and Chong Ye. "Study on spinning stability and microstructure of mesophase pitch." Materials Express 10, no. 10 (October 31, 2020): 1711–17. http://dx.doi.org/10.1166/mex.2020.1802.

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The effect of spinning temperature on phase stability, rheological stability, and thermal stability of mesophase pitch (MP), naphthalene-based mesophase pitch (AR) and microstructure of pitch filament were investigated in this study. Results showed that the interface stratification of anisotropic and isotropic phases, local enrichment of isotropic phases and extensive enrichment of isotropic phases existed in the spinning process for mesophase pitch. The local enrichment of isotropic phase was observed in MP and AR at the spinning temperature of 320 °C. The interface stratification of anisotropic and isotropic phases and extensive enrichment of isotropic phases were generated in MP when the spinning temperature reached 340 °C. This phase separation reduced the rheological stability and thermal stability of mesophase pitch and then affected the spinning ability. The inhomogeneous pores were also formed in the MP and AR mesophase pitch filament at the spinning temperature of 340 °C.

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Bailly-Reyre, Aurélien, and Hung T. Diep. "Nematic and Smectic Phases: Dynamics and Phase Transition." Symmetry 12, no. 9 (September 22, 2020): 1574. http://dx.doi.org/10.3390/sym12091574.

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We study in this paper the dynamics of molecules leading to the formation of nematic and smectic phases using a mobile 6-state Potts spin model with Monte Carlo simulation. Each Potts state represents a molecular orientation. We show that, with the choice of an appropriate microscopic Hamiltonian describing the interaction between individual molecules modeled by 6-state Potts spins, we obtain the structure of the smectic phase by cooling the molecules from the isotropic phase to low temperatures: molecules are ordered in independent equidistant layers. The isotropic-smectic phase transition is found to have a first-order character. The nematic phase is also obtained with the choice of another microscopic Hamiltonian. The isotropic-nematic phase transition is a second-order one. The real-time dynamics of the molecules leading to the liquid-crystal ordering in each case is shown by a video.

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Reyes, Catherine G., Jörg Baller, Takeaki Araki, and Jan P. F. Lagerwall. "Isotropic–isotropic phase separation and spinodal decomposition in liquid crystal–solvent mixtures." Soft Matter 15, no. 30 (2019): 6044–54. http://dx.doi.org/10.1039/c9sm00921c.

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Ji, Guangzhong, Pingsong Zhang, Rongxin Wu, Liquan Guo, Zean Hu, and Haibo Wu. "Calculation method and characteristic analysis of dispersion curves of Rayleigh channel waves in transversely isotropic media." GEOPHYSICS 85, no. 6 (November 1, 2020): C187—C198. http://dx.doi.org/10.1190/geo2019-0345.1.

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Coal seams have beddings and fissures and are typically anisotropic media. Current channel wave theories are mainly based on isotropic media, and few studies exist on the dispersion characteristics of Rayleigh channel waves in anisotropic models, such as transversely isotropic (TI) media. We chose the generalized reflection-transmission coefficient method to solve the dispersion curves of Rayleigh channel waves in TI media. However, it is difficult to solve the associated dispersion equations of Rayleigh channel waves using this method directly. Therefore, we have extended the generalized reflection-transmission coefficient method and determined the improved accuracy through numerical simulation. We analyzed the dispersion characteristics of Rayleigh channel waves of several typical coal seam models in TI media. The results showed that in the three-layer model, the difference in fundamental-mode dispersion curves between vertically transversely isotropic (VTI) media and isotropic media was relatively small; however, the differences in the higher order dispersion curves were slightly larger. The difference in the Airy phase velocity between horizontal transversely isotropic (HTI) and isotropic media was relatively large. When the coefficient of variation in the qP waves ([Formula: see text]) was greater than 0, the fundamental-mode and first-order phase velocity curves of HTI media exhibited an evident intersection at the head end. In the dirt-band-containing coal seam model, within the 350 and 550 Hz band, the high-frequency velocity of fundamental-mode phase velocity curve of isotropy and HTI media was slightly higher than the low-frequency velocity, which is a notable phenomenon.

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Kurbatov, A., A. Drozd-Rzoska, S. J. Rzoska, M. Paluch, P. Malik, J. Zioło, and J. Jadżyn. "Universal Scaling of Alpha Relaxation in Complex Liquids." Zeitschrift für Naturforschung A 56, no. 12 (December 1, 2001): 893–94. http://dx.doi.org/10.1515/zna-2001-1217.

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Abstract A plot is given, showing the result of a scaling analysis of dielectric loss curves containing, apart from low molecular glass former data (glycerol, dibutyl phtalate), also loss curves of the following liquid crystalline materials, mostly in the iso tropic phase: 4-(2-methylbutyl)-4'cyanobiphenyl (5*CB, supercooled isotropic phase), 4-cyano-4-n-alkyl biphenyls (nematogens 5CB and 8CB, isotropic phase), 4-(4-cyano-4-butylcyclohexyl)-4'-octylbiphenyl (laterally substituted nema-togen, isotropic phase), and 4-n-alkyl-4'-isothiocyanatobiphe-nyl (5 and 10 BT, isotropic and SmE phases). The plot applies the scaling formula originally proposed for glassforming, super cooled liquids [Dendzik et al.7]. The result supports the recent suggestion that dielectric relaxation in the isotropic phase of nematogens may show some features typical for "glassy" mate rials.

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Kawakatsu, Hitoshi. "A new fifth parameter for transverse isotropy." Geophysical Journal International 204, no. 1 (December 1, 2015): 682–85. http://dx.doi.org/10.1093/gji/ggv479.

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Abstract Properties of a new parameter, ηκ, that is recently introduced by Kawakatsu et al. for transverse isotropy are examined. It is illustrated that the parameter nicely characterizes the incidence angle dependence of bodywave phase velocities for vertical transverse isotropy models that share the same P- and S-wave anisotropy. When existing models of upper-mantle radial anisotropy are compared in terms of this new parameter, PREM shows a distinct property. Within the anisotropic layer of PREM (a depth range of 24.4–220 km), ηκ < 1 in the upper half and ηκ > 1 in the lower half. If ηκ > 1, anisotropy cannot be attributed to a layering of homogeneous isotropic layers, and thus requires the presence of intrinsic anisotropy.

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Gradišek, Anton, Mario Cifelli, Michal Wojcik, Tomaž Apih, Sergey Dvinskikh, Ewa Gorecka, and Valentina Domenici. "Study of Liquid Crystals Showing Two Isotropic Phases by 1H NMR Diffusometry and 1H NMR Relaxometry." Crystals 9, no. 3 (March 26, 2019): 178. http://dx.doi.org/10.3390/cryst9030178.

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In this work, we report a study of two thermotropic liquid crystalline samples showing a not common mesophase behavior. The samples, namely a di-benzyloxy biphenyl derivative labelled 9/2 RS/RS, and a bimesogenic liquid crystal labelled L1, show a direct transition between two isotropic phases followed, at lower temperatures, by the optically isotropic, 3D structured, cubic phase. These systems have been investigated by means of 1H NMR diffusometry and 1H NMR relaxometry in order to characterize their isotropic–isotropic’–cubic mesophase behavior, mainly on the dynamic point of view. In particular, the temperature trend of the self-diffusion coefficients measured for both samples allowed us to significantly distinguish between the two isotropic phases, while the temperature dependence of the 1H spin-lattice relaxation time (T1) did not show significant discontinuities at the isotropic–isotropic’ phase transition. A preliminary analysis of the frequency-dependence of 1H T1 at different temperatures gives information about the main motional processes active in the isotropic mesophases.

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de las Heras, Daniel, and Matthias Schmidt. "Bulk fluid phase behaviour of colloidal platelet–sphere and platelet–polymer mixtures." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 371, no. 1988 (April 13, 2013): 20120259. http://dx.doi.org/10.1098/rsta.2012.0259.

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Using a geometry-based fundamental measure density functional theory, we calculate bulk fluid phase diagrams of colloidal mixtures of vanishingly thin hard circular platelets and hard spheres. We find isotropic–nematic phase separation, with strong broadening of the biphasic region, upon increasing the pressure. In mixtures with large size ratio of platelet and sphere diameters, there is also demixing between two nematic phases with differing platelet concentrations. We formulate a fundamental measure density functional for mixtures of colloidal platelets and freely overlapping spheres, which represent ideal polymers, and use it to obtain phase diagrams. We find that, for low platelet–polymer size ratio, in addition to isotropic–nematic and nematic–nematic phase coexistence, platelet–polymer mixtures also display isotropic–isotropic demixing. By contrast, we do not find isotropic–isotropic demixing in hard-core platelet–sphere mixtures for the size ratios considered.

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Dissertations / Theses on the topic "Phase isotrope"

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Eich, Andreas. "Elektrorheologie homogener Systeme nematische Flüssigkristalle und isotrope Polymerlösungen /." [S.l. : s.n.], 2002. http://ArchiMeD.uni-mainz.de/pub/2002/0151/diss.pdf.

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Chang, Ze Zhou. "Etude de collisions interparticulaires en écoulement turbulent isotrope ou anisotrope par une approche lagrangienne à plusieurs trajectoires simultanées." Rouen, 1998. http://www.theses.fr/1998ROUES008.

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Une étude des interactions particule/particule est présentée suivant une simulation lagrangienne de plusieurs trajectoires simultanées et la simulation réelle des collisions entre les particules dans un écoulement turbulent donne. Un cas test en turbulence homogène isotrope, sans gravite, a ensuite été étudié et comparé à une simulation directe LES. On montre l'importance de conserver la corrélation V#PU#F globalement constante par une modification de la vitesse des particules fluides lors d'une collision. Cette modification a permis d'observer que pour un nuage distribué aléatoirement dans une turbulence isotrope ou aucune direction n'est privilégiée, les résultats ne montrent pas de variations sensibles des fluctuations de vitesses sous l'effet des collisions, mais la dispersion des particules est réduite. Un second cas test a été étudié suivant la même démarche, à savoir une turbulence de cisaillement donnée par des résultats les, afin de déterminer l'influence des collisions sur l'anisotropie du mouvement fluctuant des particules. Les résultats entre les différentes approches sont tout à fait similaires et montrent un retour vers l'isotropie des fluctuations de vitesses des particules. Enfin le couplage entre la phase dispersée et la turbulence est étudiée dans le cas d'un écoulement de tuyau. Les résultats sont en accord avec des résultats expérimentaux et montrent la diminution de l'anisotropie des deux phases sous l'effet des collisions.

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Campbell, Bernard. "Étude des cristaux liquides 8CB et 7CB en phase nématique et isotrope par la méthode de la spectroscopie dans le domaine du temps." Thèse, Université du Québec à Trois-Rivières, 1988. http://depot-e.uqtr.ca/5662/1/000569497.pdf.

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Hannebique, Grégory. "Etude de la structure des flammes diphasiques dans les brûleurs aéronautiques." Thesis, Toulouse, INPT, 2013. http://www.theses.fr/2013INPT0026/document.

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La régulation des polluants a mené à la création de nouveaux systèmes de combustion. Le carburant étant stocké sous forme liquide, sa transformation jusqu’à sa combustion est complexe. La capacité de la Simulation aux grandes échelles à simuler des écoulements turbulents réactifs a été montrée sur des cas académiques comme sur des configurations industrielles, tout en prenant en compte les phénomènes multiphysiques intervenant dans ces configurations, mais les études sur la structure de flamme diphasique sont encore trop peu nombreuses. La présence de deux solveurs pour la simulation d’une phase liquide étant disponible dans le code AVBP, leur utilisation permet une comparaison et une compréhension des phénomènes en jeu combinant dispersion, évaporation, et combustion. La première partie de l’étude relate la validation du modèle d’injection FIM-UR. Ce modèle est capable de reconstruire les profils de vitesses et de granulométrie à l’injecteur sans avoir à simuler les phénomènes d’atomisation primaire et secondaire. Une validation en régime turbulent avait déjà été réalisée, et on propose ici de valider le modèle dans un cas laminaire. Des comparaisons entre simulations monodisperses et polydisperse et des expériences sont effectuées. La simulation monodisperse Lagrangienne donne une bonne structure globale mais la simulation polydisperse Lagrangienne permet de retrouver le comportement au centre du cône avec la présence des petites gouttes et à la périphérie du cône par la présence des grosses gouttes. De plus, des améliorations sont apportées au modèle pour le formalisme Eulérien et montrent de bons résultats. La partie suivante s’intéresse à caractériser un spray polydisperse par une distribution monodisperse. En effet, au cas où une approche polydisperse n’est pas possible, le choix du diamètre moyen à prendre pour une simulation monodisperse est délicat. On propose donc d’analyser le comportement d’un spray polydisperse en le comparant à ceux de sprays monodisperses. Deux configurations académiques sont choisies : des cas de Turbulence Homogène Isotrope chargée en particules pour étudier la dynamique, et des calculs d’évaporation 0D. Trois paramètres sont étudiés pour la dynamique : la concentration préférentielle (ou ségrégation), la traînée moyenne et la traînée réduite moyenne. Cette dernière et la ségrégation de la distribution polydisperse semblent affectées par les tailles de goutte les plus faibles, et la concentration préférentielle apparait alors comme la moyenne des ségrégations des classes qui la composent pondérées par l’inverse du nombre de Stokes associé à chacune de ces classes. La traînée moyenne de la simulation polydisperse possède un comportement proche des diamètres moyens D10 et D20. Ces analyses nous poussent donc à choisir le D10 pour caractériser la dynamique d’un spray polydisperse. Les calculs d’évaporation 0D ne permettent pas dans un premier temps de caractériser efficacement la masse évaporée d’un spray polydisperse par celle d’un spray monodisperse équivalent, mais la définition de nouveaux diamètres issus de la littérature des lits fluidisés comme le D50% le permet, ce qui le place autour du D32. On propose donc de caractériser l’évaporation d’un spray polydisperse par ce diamètre. Enfin, la dernière partie étudie la structure de flamme diphasique dans la chambre MERCATO, à l’aide du formalisme Lagrangien, monodisperse et polydisperse, mais aussi en utilisant le formalisme Eulérien. La validation du modèle FIM-UR du premier chapitre et ses améliorations sont utilisées pour représenter les conditions d’injection liquide. En plus d’un calcul polydisperse, deux simulations monodisperses Lagrangiennes sont réalisées en prenant les diamètres moyens D10 et D32, suite à la partie précédente. Des comparaisons qualitatives et des validations sont réalisées, en comparant des profils de vitesses gazeuses axiale et fluctuante et vitesse axiale liquide issus de l’expérience
Regulations on pollutants have led to the creation of new combustion systems. Giving that fuel is stored in a liquid form, its evolution until combustion is complex. The ability of Large Eddy Simulation has been demonstrated on academic cases, as well as on industrial configurations, by taking into account the multi-physics phenomena, but there is a lack of studies about two-phase flow flame structures. Two solvers for the simulation of two-phase flows are available in the AVBP code, hence both simulations are performed to compare and increase understanding of the phenomena involved such as dispersion, evaporation and combustion. The first part of the study focuses on the validation of the FIM-UR injection model. This model is able to build velocity and droplet profiles at the injector, without simulating primary and secondary break up. A validation in a turbulent case has already been done, and this study validates the model in a laminar case. Comparisons between monodisperse and polydisperse simulations, and experiments are performed. The monodisperse Lagrangian simulation shows good results but the polydisperse simulation is able to represent profiles in the center of the cone by small droplets and at the peripheral part of the cone, by big ones. Moreover, improvements in the Eulerian model exhibit good results. The next section tries to evaluate the impact of polydispersion. Indeed, when a polydisperse approach is not available, choosing the mean diameter can be tricky. A comparison between the behavior of polydisperse spray and monodisperse sprays ones is realised. Two academic cases are studied: Homogeneous Isotropic Turbulence with particles to analyze the dynamics, and 0D evaporation cases. For the dynamics, preferential concentration, mean drag and reduced mean drag are studied. The latter and preferential concentration are affected by small droplets, and the preferential concentration of a polydisperse spray is equivalent to the average of preferential concentration of classes, extracted from the polydisperse distribution, weighted by the inverse of the Stokes number of each class. The mean drag behaves like the D10 and D20 mean drags. This analysis allows us to choose the D10 to characterize a polydisperse distribution for the dynamics. Zero-D evaporation simulations cannot characterize the polydisperse spray evaporated mass by the evaporated mass of monodisperses sprays. New definitions of diameters from fluidized bed literature enable the use of D50%, which is close to D32. We propose to use this diameter to characterize the evaporation of a polydisperse spray. Finally, the last section studies the structure of two-phase flames in the MERCATO bench, using the Lagrangian formalism, monodisperse and polydisperse but also using the Eulerian formalism. The validation of FIM-UR model and improvements from the first section are used to represent liquid injection conditions. A polydisperse simulation is realized and two monodisperse simulations are computed using mean diameters D10 and D32, thanks to the previous section. Qualitative comparisons and validations are realized, comparing gaseous velocity profiles and liquid velocity profiles. Good agreements are found and the mean diameter D32 seems to be close to the polydisperse spray. A comparison between mean flames is done with an Abel transform of the flame from the experiments. The flame has an "M shape", anchored by small recirculation zones out of the swirler, and by a point at the tip of the central recirculation zone. Then, the impact of droplet distributions is analyzed. Even if few bigger droplets from the polydisperse distribution are convected in the hot gases due to bigger particular time and evaporation time, two-phase flow flame structures are equivalent. Different combustion regimes appeared with premixed flames and pockets of fuel burning in the hot gases

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Elhimer, Medhi. "The dynamics of neutrally buoyant particles in isotropic turbulence : an experimental study." Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0049/document.

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Le but de cette étude expérimentale est de caractériser la dynamique de particules solides, à flottabilité nulle, incluse dans un écoulement turbulent isotrope en décroissance libre. Les particules utilisées sont de forme sphérique et ont un diamètre de 4 à 5 fois plus grand que l'échelle spatial de Kolmogorov de l'écoulement. De part leur taille, les particules ont également un nombre de Stokes proche de l'unité. On s'attend alors à ce que ces particules aient une dynamique différente de celle du fluide environnant. Dans cette étude, ont se propose de quantifier les différences de vitesses entre les deux phases à l'aide d'une technique de vélocimétrie simultanée
In this experimental study, the focus is made on the characterization of the dynamics of solid neutrally buoyant particles embedded in a freely decaying, nearly isotropic turbulence, with a weak mean flow. The particles are spherical with diameters several times larger than the Kolmogorov scale. The study of this flow configuration is still challenging both theoretically and numerically. Due to large particle sizes, the local flow around particles can not be considered as uniform and due to fluid-particle density ratio of around unity, the history and Basset forces cannot be neglected in comparison with the viscous drag force. Particle equation of motion is then fully non-linear, in contrast to the equation for heavy particles with diameters smaller then the Kolmogorov scale, for which only the Stokes drag is considered. In several experimental and numerical studies, the effect of particle size on velocity and acceleration statistics has been investigated (Homann and Bec 2010 ; Qureshi et al. 2008 ; Ouellette et al. 2008 ; Xu and Bodenschatz 2008). In the case of isotropic turbulence, Homann and Bec (2010) show that while the PDF of the particle velocity normalized by the square root of its variance does not vary with particle size, the variance itself is size dependent. A scaling relation for particle velocity variance has been proposed by using the Faxen correction (Gatignol 1983) which takes into account the non uniformity of the fluid flow at the scale of the particle. The aim of our research is to further study the dependence of particle dynamics on particle size. To that purpose, a turbulence generator has been set-up and the resulting turbulence is characterized. Then the flow was seeded with millimeter sized, neutrally-buoyant particles and the velocity of the two phases have been measured simultaneously. Simultaneous measurements of particle and surrounding fluid velocities show that although the global velocity statistics of the two phases have comparable values, the particles may have different local velocity from the velocity of the neighboring fluid

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Kahl, Philipp. "Identification of long-range solid-like correlations in liquids and role of the interaction fluid-substrate." Thesis, Le Mans, 2016. http://www.theses.fr/2016LEMA1002/document.

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Les liquides diffèrent des solides par une réponse retardée à la sollicitation en cisaillement; c’est-à-dire une absence d’élasticité de cisaillement et un comportement d'écoulement à basses fréquences (<1 Hz). Ce postulat pourrait ne pas être vrai à toutes échelles. A l’échelle submillimétrique, les mesures viscoélastiques (VE) réalisées en améliorant l'interaction entre le liquide et le substrat, montrent qu’une élasticité basses-fréquences existe dans des liquides aussi variés que les polymères, les surfondus, les liquides à liaison H, ioniques ou van der Waals. Ce résultat implique que les molécules à l'état liquide ne seraient pas dynamiquement libres, mais élastiquement corrélées.En utilisant les propriétés biréfringentes des fluctuations prétransitionnelles qui coexistent dans la phase isotrope des cristaux liquides, nous montrons qu'il est possible de visualiser ces corrélations « cachées ». Dans des conditionssimilaires aux mesures VE, une biréfringence optique synchrone à la déformation est observée dans la phase isotrope à des fréquences aussi basses que 0.01 Hz et des températures éloignées de toute transition. Le comportement dela biréfringence basses-fréquences a des similitudes avec l'élasticité; elle est en phase avec la déformation à faibles amplitudes de déformation, puis en phase avec le taux de déformation à plus grandes amplitudes. La biréfringence basses- fréquences est forte, sans défaut et réversible. Elle indique un ordre à longue portée. La synchronisation de la réponse à la sollicitation en fréquence et l’état ordonné qu’elle produit ne sont pas compatibles avec un état liquide isotrope mais montrent qu’il s’agit d’un état élastique soumis à déformation (entropie élastique)
Liquids differ from solids by a delayed response to a shear mechanical solicitation; i.e. they have no shearelasticity and exhibit a flow behaviour at low frequency (<1 Hz). This postulate might be not verified at thesub-millimeter scale. By optimizing the measurement in particular by improving the liquid/substrate interactions (wetting), a low frequency shear elasticity has been found in liquids including molten polymers, glass-formers, H-bond polar, ionic or van der Waals liquids. This result implies that molecules in the liquid state may not be dynamically free but weaklyelastically correlated. Using the birefringent properties of the pretransitional fluctuations coexisting in the isotropic phase of liquid crystals, we show that it is possible to visualize these “hidden” shear-elastic correlations. We detect a synchronized birefringent optical response in the isotropic phase that is observable at frequencies as low as 0.01 Hz and at temperatures far away from anyphase transition. The low-frequency birefringence exhibits a strain dependence similar to the low frequency elasticity: An optical signal that is in-phase with the strain at low strain amplitudes and in-phase with the strain-rate at larger strain amplitudes. The birefringent response is strong, defect-free, reversible and points out a collective response. This long-range ordering rules out the condition of an isotropic liquid and its synchronized response supports the existenceof long-range elastic (solid-like) correlations. In the light of this, the strain dependence of the harmonic birefringent signal and the shear elasticity may correspond to an entropy-driven transition

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Birlenbach, Lars. "Strömungsorientierung und Vorumwandlungserscheinungen in der isotropen Phase thermotroper Flüssigkristalle." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972553479.

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Nguyen, Hoang-Phuong. "Structure and elasticity of nematic and isotropic liquid crystals." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=96397677X.

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Haïdar, Riad. "Nouveaux scenarii de quasi-accord de phase dans les semiconducteurs isotropes." Paris 11, 2003. http://www.theses.fr/2003PA112117.

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Les sources émettant dans la région du moyen infrarouge revêtent un grand intérêt environnemental et écologique. Les semiconducteurs de la branche électronique, tels que le séléniure de zinc ou l'arseniure de gallium, sont d'excellents candidats pour la conversion d'un rayonnement optique du proche vers le moyen infrarouge. Ces matériaux sont cependant isotropes, et seule la technique du quasi-accord de phase permet de réaliser une conversion efficace. Ce travail concerne le quasi-accord de phase par réflexion. Lés conditions d'accord de phase sont obtenues par biréfringence de Fresnel en réflexion interne totale. Il est montré que cette technique est analogue dans son principe à celle de l'accord de phase par biréfringence naturelle: on parle donc d'accord de phase de Fresnel. Deux situations schématiques sont analysées. La première est celle du quasi-accord de phase résonnant classique: le modèle théorique que nous avons développé prédit correctement les observations expérimentales. La seconde est une particularité de l'accord de Fresnel: il s'agit du quasi-accord de phase non résonnant, qui permet d'alléger considérablement les conditions d'accord de phase et autorise une grande accordabilité spectrale. L'influence de facteurs limitants est également quantifiée. Ainsi, le décalage de Goos-Hänchen rappelle, par ses effets, le walk-off classique. Ceci limite en fait les dimensions de la plaque. Cependant, le facteur le plus sévèrement limitant s'avère être la rugosité de surface: en effet, ce paramètre suffit seul à quantifier l'efficacité de toute la structure. Des calculs du seuil d'oscillation paramétrique optique sont développés sur la base de la formule de Brosnan et Byer. La fluorescence paramétrique a été observée dans une plaque en accord de Fresnel. Les premières estimations du seuil d'oscillation sont prometteuses
Mid-infrared tunable sources are becoming of considerable interest for applications in environmental monitoring. Semiconductors of the technological mainstream (such as gallium arsenide or zinc selenide) are excellent candidates for optical conversion of near-infrared waves into the mid-infrared range. However, these materials are isotropic, so that quasiphase-matching scenarios are needed to get an efficient conversion. Reflection quasiphase-matching techniques are studied here. We make use of the Fresnel birefringence at total internal reflection to reach the phase-matching conditions in a plane parallel plate. It is shown that this technique is very similar in its principle to the natural birefringence phase-matching : we thus call it Fresnel phase-matching. Two schematic situations are explored. First, a model of classical resonant quasi-phase matching scenario is presented; the agreement between theoretical predictions and experimental results is convincing. Second, the Fresnel birefringence allows a new non-resonant quasiphase-matching scenario: this appears to greatly alleviates the phase-matching conditions and provides a high tenability. The impact of restricting factors is also quantified. So, the Goos-Hänchen shift is similar, in terms of conversion yield, to the classical walk-off. This actually limits the dimensions of the plate. However, the most inhibiting parameter appears to be the surface roughness : indeed, this sole factor is enough to determine the conversion efficiency of the whole structure. Optical parametric oscillation threshold calculations based on the Brosnan and Byer formula are finally presented. Parametric fluorescence is measured in a Fresnel phase-matched plate. The first estimations of the oscillation threshold are promising

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10

Raybaut, Myriam. "Sources paramétriques optiques innovantes à base de semiconducteurs isotropes." Paris 11, 2006. http://www.theses.fr/2006PA112238.

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Diverses applications, telles que la détection de polluants ou neurotoxiques, nécessitent de disposer de sources optiques accordables intenses dans l’infrarouge (IR) moyen (8–12 µm). Une voie bien adaptée pour répondre à ces besoins est d’utiliser l’optique non linéaire pour convertir vers l’IR moyen le rayonnement d’un laser émettant dans l’IR proche. Cependant, les matériaux non linéaires usuels ne peuvent être utilisés pour la bande 8–12 µm car ils absorbent au-delà de 4 µm. Afin de s’affranchir de cette limitation, nous étudions ici l’utilisation des semiconducteurs isotropes comme matériaux non linéaires alternatifs. En effet, ces matériaux (GaAs, ZnSe, etc. ) présentent de forts coefficients non linéaires, et sont transparents dans l’IR moyen. Comme ces matériaux sont isotropes, des techniques de quasi-accord de phase doivent être mises en place pour une conversion non linéaire efficace. La technique choisie ici est celle de la biréfringence de Fresnel. Nous avons étudié cette technique aussi bien d’un point de vue expérimental par des expériences de différence de fréquences dans GaAs entre deux faisceaux proche IR accordables (~1,9 µm et 2,4 µm), que d’un point de vue théorique par le développement de nouveaux modèles prenant en compte tous les processus linéaire et non linéaire intrinsèques à la biréfringence de Fresnel. Enfin, cette technique d’accord de phase a été appliquée à l’auto-différence de fréquences dans les lasers ZnSe:Cr afin de générer une onde IR moyen à partir d’un faisceau pompe unique. L’onde à 10 µm est alors générée par différence de fréquences entre l’onde pompe à 1,9 µm et l’onde laser émise par les ions Cr2+ autour de 2,3 µm
Tunable mid-infrared (IR) sources are of high interest for many applications, including chemical monitoring, gas analysis, remote sensing, and IR countermeasures. A promising way to obtain such mid-IR emission is to use optical sources based on parametric conversion in nonlinear materials. However, apart from few materials (ZnGeP2, AgGaSe2, CdSe,…), most of usual nonlinear materials exhibit strong multiphonon absorption beyond 5 µm. Therefore, an important issue is to find adequate materials for the 8﷓12 µm band. In this context, semiconductors of the technological mainstream, such as GaAs or ZnSe, are excellent candidates for mid-infrared parametric generation. Indeed, they display high non linear susceptibility and they are transparent from the near-infrared up to 20 µm. However, since these materials are isotropic, quasi-phase-matching techniques have to be implemented to get an efficient conversion. Nonetheless, this limitation can be overcome using Fresnel birefringence that takes place at total internal reflection. We present here an experimental and theoretical study of this phase matching technique : difference frequency generation experiments are carried out and new models are developped to take into account all the physical processes involved. We investigate then self-difference frequency mixing in Cr:ZnSe laser using Fresnel phase matching. Taking advantage of both the lasing and nonlinear properties of this material, we demonstrate that 8–12 µm radiation can be produced using a single pump beam at 1. 9 µm. Subsequently, difference frequency mixing between the 1. 9µm pump beam and 2. 3µm laser beam produces a mid-IR radiation in the 9 µm range

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Books on the topic "Phase isotrope"

1

Marques, Elizabeth R. C. Stress waves in transversely isotropic media: The homogeneous problems. Cleveland, Ohio: Lewis Research Center, 1986.

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H, Williams James, United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch., and Lewis Research Center, eds. Stress waves in transversely isotropic media: The homogeneous problem. [Washington, D.C.]: National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1986.

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Thurner, Stefan, Rudolf Hanel, and Peter Klimekl. Networks. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198821939.003.0004.

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Understanding the interactions between the components of a system is key to understanding it. In complex systems, interactions are usually not uniform, not isotropic and not homogeneous: each interaction can be specific between elements.Networks are a tool for keeping track of who is interacting with whom, at what strength, when, and in what way. Networks are essential for understanding of the co-evolution and phase diagrams of complex systems. Here we provide a self-contained introduction to the field of network science. We introduce ways of representing and handle networks mathematically and introduce the basic vocabulary and definitions. The notions of random- and complex networks are reviewed as well as the notions of small world networks, simple preferentially grown networks, community detection, and generalized multilayer networks.

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Book chapters on the topic "Phase isotrope"

1

Vanweert, F., and W. Van Dael. "Optical Activity in the Isotropic and Blue Phases of a Chiral Liquid Crystal." In Phase Transitions in Soft Condensed Matter, 91–94. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4613-0551-4_9.

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Roux, D., and M. E. Cates. "The Sponge State: A Striking Isotropic Liquid Phase." In Springer Proceedings in Physics, 19–33. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-76008-2_2.

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Ordonez, Andres F., and Olga Smirnova. "Inducing Enantiosensitive Permanent Multipoles in Isotropic Samples with Two-Color Fields." In Molecular Beams in Physics and Chemistry, 335–52. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63963-1_16.

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AbstractWe find that two-color fields can induce field-free permanent dipoles in initially isotropic samples of chiral molecules via resonant electronic excitation in a one-$$3\omega $$ 3 ω -photon versus three-$$\omega $$ ω -photons scheme. These permanent dipoles are enantiosensitive and can be controlled via the relative phase between the two colors. When the two colors are linearly polarized perpendicular to each other, the interference between the two pathways induces excitation sensitive to the molecular handedness and orientation, leading to uniaxial orientation of the excited molecules and to an enantio-sensitive permanent dipole perpendicular to the polarization plane. We also find that although a corresponding one-$$2\omega $$ 2 ω -photon versus two-$$\omega $$ ω -photons scheme cannot produce enantiosensitive permanent dipoles, it can produce enantiosensitive permanent quadrupoles that are also controllable through the two-color relative phase.

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Etchepare, J., G. Grillon, I. Thomazeau, G. Hamoniaux, and A. Orszag. "Phase Grating Approach to Susceptibility Tensors: Determination in Isotropic Media." In Springer Series in Chemical Physics, 504–9. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-82918-5_135.

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Maeda, T. "The Dynamical Structure Factor of Rodlike Polymers in the Isotropic Phase." In Springer Proceedings in Physics, 76–77. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-76008-2_13.

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Chandrakumar, Narayanan. "NMR of Systems Involving Spin-1 Nuclei in the Isotropic Phase." In Spin-1 NMR, 27–58. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-642-61089-9_2.

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Lee, Suk Bin, and Anthony D. Rollett. "Three Dimensional Monte Carlo Simulation of Isotropic Coarsening of Particles in Liquid Phase." In Materials Science Forum, 1115–20. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-443-x.1115.

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Bülow, Thomas, Dieter Pallek, and Gerald Sommer. "Riesz Transforms for the Isotropic Estimation of the Local Phase of Moire Interferograms." In Informatik aktuell, 333–40. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-642-59802-9_42.

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Singh, Alok, Y. Osawa, H. Somekawa, and T. Mukai. "Improved Processing of Mg-Zn-Y Alloys Containing Quasicrystal Phase for Isotropie High Strength and Ductility." In Magnesium Technology 2011, 239–44. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118062029.ch46.

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Zachmann, H. G., D. Chen, J. Nowacki, E. Olbrich, and C. Schulze. "Molecular Order, Morphology and Phase Separation in Blends of Isotropic and Liquid-Crystalline Polymers." In Integration of Fundamental Polymer Science and Technology—4, 242–60. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0767-6_29.

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Conference papers on the topic "Phase isotrope"

1

Oh, Jeonghun, Moosung Lee, Seungwoo Shin, and Yongkeun Park. "Realization of isotropic resolution in optical diffraction tomography by exploiting a tomographic mould for optical trapping." In Quantitative Phase Imaging V, edited by Gabriel Popescu and YongKeun Park. SPIE, 2019. http://dx.doi.org/10.1117/12.2513335.

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Cinquemani, Simone, Hermes Giberti, and Giovanni Legnani. "Continuum Isotropy Loci of a 2-DoF Parallel Kinematic Manipulator." In ASME 2012 11th Biennial Conference on Engineering Systems Design and Analysis. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/esda2012-82514.

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Parallel Kinematic Machines (PKM) are interesting in industrial field because of their ability to ensure high dynamic performance, stiffness, accuracy and precision. One of the parameters used in the design phase of a manipulator relates the opportunity to ensure isotropic performance within the workspace. This paper presents a methodology to graphically identify the points of isotropy of a planar manipulator and defines the geometrical conditions to maximize the number. It is demonstrated that, for some configurations of the manipulator, continuum isotropy loci can be identified. Achieving this goal ensures the efforts related to the design of a manipulator are paid in terms of ability to work, as much as possible, with ideal kinematical conditions.

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Kitchenside, Philip W. "Phase shift‐based migration for transverse isotropy." In SEG Technical Program Expanded Abstracts 1991. Society of Exploration Geophysicists, 1991. http://dx.doi.org/10.1190/1.1888796.

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Lin, Yu-Zi, Hsi-Hsun Chen, Kuang-Yuh Huang, and Yuan Luoc. "Isotropic quantitative differential phase contrast microscopic imaging." In Biomedical Imaging and Sensing Conference, edited by Osamu Matoba, Yasuhiro Awatsuji, Yuan Luo, Toyohiko Yatagai, and Yoshihisa Aizu. SPIE, 2018. http://dx.doi.org/10.1117/12.2316751.

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Palto, S. P., T. Sergan, Georges E. Durand, C. Germain, J. Malthete, and A. Moradpour. "Photoinduction of nematic order in isotropic phase." In International Liquid Crystal Workshop: Surface Phenomena, edited by Evgenij Rumtsev and Maxim G. Tomilin. SPIE, 1996. http://dx.doi.org/10.1117/12.230636.

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Fan, Yao, Jiasong Sun, Qian Chen, Xiangpeng Pan, and Chao Zuo. "Isotropic quantitative phase imaging with optimal differential phase contrast illumination scheme." In Seventh International Conference on Optical and Photonic Engineering (icOPEN 2019), edited by Motoharu Fujigaki, Huimin Xie, Qican Zhang, Song Zhang, Jianguo Zhu, Qian Kemao, and Anand Asundi. SPIE, 2019. http://dx.doi.org/10.1117/12.2547850.

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Araoka, Fumito, Satoshi Aya, Khoa V. Le, and Hideo Takezoe. "Optical isotropic phases towards display application." In SPIE OPTO, edited by Karlheinz Blankenbach, Liang-Chy Chien, Sin-Doo Lee, and Ming Hsien Wu. SPIE, 2011. http://dx.doi.org/10.1117/12.881133.

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Beese, A. M., D. Mohr, and P. O. Santacreu. "Isotropic Phase Transformation in Anisotropic Stainless Steel 301LN Sheets." In ESOMAT 2009 - 8th European Symposium on Martensitic Transformations. Les Ulis, France: EDP Sciences, 2009. http://dx.doi.org/10.1051/esomat/200902001.

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Jadzyn, Jan, Christian Legrand, B. Zywucki, Grzegorz Czechowski, and Roman S. Dabrowski. "Dielectric relaxation in isotropic phase of mesomorphic n-TPEB's." In Liquid and Solid State Crystals: Physics, Technology, and Applications, edited by Jozef Zmija. SPIE, 1993. http://dx.doi.org/10.1117/12.156978.

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Yaroshchuk, Oleg V., Dmitry A. Voloshchenko, Victor Y. Reshetnyak, and G. Pelzl. "Saturating holograms due to space-modulated phase-transition LC-isotropic phase in liquid crystals." In Holography, Correlation Optics, and Recording Materials, edited by Oleg V. Angelsky. SPIE, 1993. http://dx.doi.org/10.1117/12.165366.

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Reports on the topic "Phase isotrope"

1

Kamrath, Matthew, Vladimir Ostashev, D. Wilson, Michael White, Carl Hart, and Anthony Finn. Vertical and slanted sound propagation in the near-ground atmosphere : amplitude and phase fluctuations. Engineer Research and Development Center (U.S.), May 2021. http://dx.doi.org/10.21079/11681/40680.

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Sound propagation along vertical and slanted paths through the near-ground atmosphere impacts detection and localization of low-altitude sound sources, such as small unmanned aerial vehicles, from ground-based microphone arrays. This article experimentally investigates the amplitude and phase fluctuations of acoustic signals propagating along such paths. The experiment involved nine microphones on three horizontal booms mounted at different heights to a 135-m meteorological tower at the National Wind Technology Center (Boulder, CO). A ground-based loudspeaker was placed at the base of the tower for vertical propagation or 56m from the base of the tower for slanted propagation. Phasor scatterplots qualitatively characterize the amplitude and phase fluctuations of the received signals during different meteorological regimes. The measurements are also compared to a theory describing the log-amplitude and phase variances based on the spectrum of shear and buoyancy driven turbulence near the ground. Generally, the theory correctly predicts the measured log-amplitude variances, which are affected primarily by small-scale, isotropic turbulent eddies. However, the theory overpredicts the measured phase variances, which are affected primarily by large-scale, anisotropic, buoyantly driven eddies. Ground blocking of these large eddies likely explains the overprediction.

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