Bibliographies thématiques / Anisotropy reduction

Littérature scientifique sur le sujet « Anisotropy reduction »

Auteur : Grafiati
Publié le 4 mai 2024

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Articles de revues sur le sujet "Anisotropy reduction"

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Grudinin, Dmitriy, Olga Matveeva, Georgy Ermolaev, Andrey Vyshnevyy, Aleksey Arsenin et Valentyn Volkov. « Reduction in Crosstalk between Integrated Anisotropic Optical Waveguides ». Photonics 10, no 1 (5 janvier 2023) : 59. http://dx.doi.org/10.3390/photonics10010059.

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The minimization of waveguide crosstalk is a long-standing challenge for optical engineers. Nowadays, the most popular technique to suppress crosstalk is anisotropic nanostructures, realized as subwavelength stripes between waveguides. However, the influence of material anisotropy on the efficiency of such structures remains unknown. In this work, we consider MoS2 waveguides separated by MoS2 stripes because this material has the record value of optical anisotropy. We discover that the use of MoS2 instead of Si results in a several-orders-of-magnitude-larger crosstalk distance. Therefore, we envision that by combining the extraordinary material properties with the known crosstalk-suppression methods, one can make the integration density of photonic devices close to electronics.
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Lim, Young Soo, Bae Gun Park et Gil-Geun Lee. « Synthesis of N-type Bi2Te2.7Se0.3 Compounds through Oxide-Reduction Process and Related Thermoelectric Transport Properties ». Korean Journal of Metals and Materials 60, no 6 (5 juin 2022) : 463–70. http://dx.doi.org/10.3365/kjmm.2022.60.6.463.

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We present a study on the synthesis of Bi2Te2.7Se0.3 powders through an oxide reduction process and also on the effect of the oxide reduction process on the thermoelectric transport properties of the resulting Bi2Te2.7Se0.3 compounds. Starting materials of Bi2O3, TeO2 and SeO2 were mechanical milled for homogeneous mixing, and then oxidized to prepare complex oxide powders. The complex oxide powders were reduced at different reduction temperatures under hydrogen atmosphere, and a single phase of Bi2Te2.7Se0.3 could be achieved in the reduced powder, with shorter reduction times as the reduction temperature was increased. The shape of the synthesized powder particles changed from granules to flakes with increasing reduction temperature and longer reduction time. Bi2Te2.7Se0.3 powders with different shapes were consolidated by spark plasma sintering (SPS). The SPSed Bi2Te2.7Se0.3 compounds exhibited anisotropic n-type thermoelectric transport properties along the vertical and parallel planes with respect to the pressing direction of the SPS. The degree of anisotropy in the thermoelectric properties was quite consistent with the degree of anisotropy in the microstructure, which originated from the anisotropic shapes in the Bi2Te2.7Se0.3 powders depending on the reduction conditions. Detailed thermoelectric transport properties of the n-type Bi2Te2.7Se0.3 compounds were interpreted in terms of anti-site defect formation and their structural anisotropy.
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FROHNAPFEL, B., P. LAMMERS, J. JOVANOVIĆ et F. DURST. « Interpretation of the mechanism associated with turbulent drag reduction in terms of anisotropy invariants ». Journal of Fluid Mechanics 577 (19 avril 2007) : 457–66. http://dx.doi.org/10.1017/s0022112007005083.

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A central goal of flow control is to minimize the energy consumption in turbulent flows and nowadays the best results in terms of drag reduction are obtained with the addition of long-chain polymers. This has been found to be associated with increased anisotropy of turbulence in the near-wall region. Other drag reduction mechanisms are analysed in this respect and it is shown that close to the wall highly anisotropic states of turbulence are commonly found. These findings are supported by results of direct numerical simulations which display high drag reduction effects of over 30% when only a few points inside the viscous sublayer are forced towards high anisotropy.
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Tong, P., W. I. Goldburg, J. S. Huang et T. A. Witten. « Anisotropy in turbulent drag reduction ». Physical Review Letters 65, no 22 (26 novembre 1990) : 2780–83. http://dx.doi.org/10.1103/physrevlett.65.2780.

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Choi, Seungsoon, Olivier Fabbri, Gültekin Topuz, Aral I. Okay et Haemyeong Jung. « Twin Induced Reduction of Seismic Anisotropy in Lawsonite Blueschist ». Minerals 11, no 4 (10 avril 2021) : 399. http://dx.doi.org/10.3390/min11040399.

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Lawsonite is an important mineral for understanding seismic anisotropy in subducting oceanic crust due to its large elastic anisotropy and prevalence in cold subduction zones. However, there is insufficient knowledge of how lawsonite twinning affects seismic anisotropy, despite previous studies demonstrating the presence of twins in lawsonite. This study investigated the effect of lawsonite twinning on the crystal preferred orientation (CPO), CPO strength, and seismic anisotropy using lawsonite blueschists from Alpine Corsica (France) and the Sivrihisar Massif (Turkey). The CPOs of the minerals are measured with an electron backscatter diffraction instrument attached to a scanning electron microscope. The electron backscatter diffraction analyses of lawsonite reveal that the {110} twin in lawsonite is developed, the [001] axes are strongly aligned subnormal to the foliation, and both the [100] and [010] axes are aligned subparallel to the foliation. It is concluded that the existence of twins in lawsonite could induce substantial seismic anisotropy reduction, particularly for the maximum S-wave anisotropy in lawsonite and whole rocks by up to 3.67% and 1.46%, respectively. Lawsonite twinning needs to be considered when determining seismic anisotropy in the subducting oceanic crust in cold subduction zones.
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Elliott, Jacob C., Andrea Arguelles et Julianna Simon. « Histotripsy bubble dynamics in tendon and anisotropic gel phantoms ». Journal of the Acoustical Society of America 151, no 4 (avril 2022) : A31. http://dx.doi.org/10.1121/10.0010561.

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Collagenous, anisotropic tissues such as tendon have demonstrated resistance to liquefaction by histotripsy, despite the creation, oscillation, and collapse of bubbles verified using B-mode imaging. The objective of this work is to evaluate effects of anisotropy on bubble dynamics in tissue-mimicking hydrogels and compare to anisotropic tissues. Polyacrylamide, fibrin, and collagen hydrogels were fabricated; ex vivo bovine tendons were obtained. Sound speeds were measured in each axial direction to evaluate degree of anisotropy. Hydrogels and tendons were exposed to 1.5-MHz focused ultrasound with 10-ms pulses repeated at 1-Hz with p + =89 MPa, p − = 26 MPa. Cavitation activity was monitored with simultaneous high-speed photography and passive cavitation imaging using a Philips/ATL L7-4 transducer and Vantage® ultrasound system. Violent cavitation activity and fractionation was observed in polyacrylamide, collagen, and fibrin hydrogels with low degrees of anisotropy (<1.2); such behavior is unlike that of tendon. Dehydration of fibrin gels resulted in a 55% reduction in peak cavitation emission energy and a 260% increase in anisotropy compared to standard fibrin formulations. These gels demonstrated similar cavitation energy than tendon (within 4%) but 50% less anisotropy, indicating more hydrogel formulations should be explored to better mimic collagenous, anisotropic tissue. [Work supported by NIH R21EB027886.]
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Bachrach, Ran. « Elastic and resistivity anisotropy of shale during compaction and diagenesis : Joint effective medium modeling and field observations ». GEOPHYSICS 76, no 6 (1 novembre 2011) : E175—E186. http://dx.doi.org/10.1190/geo2010-0381.1.

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Shales are anisotropic materials which have been observed to have both electrical and elastic anisotropy. Shales also comprise most of the sedimentary column in clastic basins, and thus, the ability to model shale response to electrical and seismic fields may improve our ability to better resolve anisotropy by using different measurements. Compacting shale-effective media modeling, which captures the geological process of porosity reduction and geochemical compaction, was formulated in this research in microstructural parameters associated with particle alignment and pore-shape deformation. The state of compaction, captured by the porosity of the soft sediment, governs the pore aspect ratio and the amount of particle alignment. Diagenetic processes are captured using temperature-dependent mineral elasticity and conductivity. The model uses the same microstructural parameters and equivalent effective medium approximation scheme to predict electrical and elastic anisotropy. In situ measurements of electrical anisotropy and seismic based estimates of elastic anisotropy in shales in the same basin compare favorably with modeling results. The joint-modeling formulation provides ways to study electrical resistivity and elastic-anisotropy jointly and explore the use of electrical resistivity anisotropy measurements to constrain elastic anisotropy, and vice versa.
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Wang, Yangxin, Aijun Li, Chundong Hu, Xiaofei Guo, Xufei Li, Wenzhen Bi, Xicheng Wei et Han Dong. « Microstructure, Texture, and Anisotropic Properties of High-Strength Low-Alloy Steel ». Coatings 13, no 8 (16 août 2023) : 1442. http://dx.doi.org/10.3390/coatings13081442.

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The effects of cold rolling reduction rates and recrystallization annealing temperature on the microstructure, texture, and anisotropic properties of high-strength low-alloy (HSLA) steel were investigated using scanning electron microscopy and electron backscatter diffraction. The results revealed that the constituents of recrystallized, substructured, and deformed structures were strongly affected by cold rolling reduction rates ranging from 33.3% to 66.7% and recrystallization temperatures ranging from 780 to 840 °C. At an annealing temperature of 820 °C, when the cold rolling reduction rate was 33.3%, HSLA steel exhibited a low percentage of recrystallization, with cubic, γ-linear, rolled, and Z-texture (the texture at Euler angles φ1 = 30° and Φ = 20°–30°) structures. The rolled texture and Z-texture increased the strength anisotropy and disappeared at high cold rolling reduction rates. When the annealing temperature was increased from 780 °C to 820 °C, the proportion of recrystallized grains increased, the rolling texture disappeared, and grain orientation gradually gathered in the cubic texture and γ line texture, resulting in low anisotropy of strength. At an annealing temperature of 840 °C, the deformation of the grain disappeared; however, the anisotropy increased compared to annealing at 820 °C because of the formation of a new texture of {001}<−1–20>.
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Jung, I., D. Chae et Bruno C. De Cooman. « Influence of the Cold Rolling Reduction on the Texture Development and r-Value Anisotropy in Ti-Stabilized 18% Cr Ferritic Stainless Steel ». Solid State Phenomena 160 (février 2010) : 129–34. http://dx.doi.org/10.4028/www.scientific.net/ssp.160.129.

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Ti stabilized AISI 439 type 18% Cr ferritic stainless steel offers an attractive alternative for replacing Ni-containing austenitic steels. The influence of the cold rolling reduction on texture development and the planar anisotropy of Ti-stabilized 18% Cr ferritic stainless steel have been studied in order to find an optimized processing route to obtain improved formability properties. In the present study, both annealed and un-annealed hot strips were given different cold rolling reductions up to 86%, and recrystallization annealed. The recrystallization texture was analyzed by means of XRD. Tensile tests were carried out on cold rolled and annealed samples oriented in seven different directions to the rolling direction to evaluate the planar anisotropy in detail. The mean normal anisotropy rm increased with increasing cold reduction for both annealed hot band and un-annealed hot band. The planar anisotropy revealed a behavior related to the development of the recrystallization texture component in the annealed hot band and the texture component in the un-annealed hot band, with increasing cold reduction.
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Vernik, Lev, et Xingzhou Liu. « Velocity anisotropy in shales : A petrophysical study ». GEOPHYSICS 62, no 2 (mars 1997) : 521–32. http://dx.doi.org/10.1190/1.1444162.

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Using ultrasonic velocity and anisotropy measurements on a variety of shales with different clay and kerogen content, clay mineralogy, and porosity at a wide range of effective pressure, we find that elastic anisotropy of shales increases substantially with compaction. The effect is attributed to both porosity reduction and smectite‐ to‐illite transformation with diagenesis. A means of kerogen content mapping using velocity versus porosity crossplot for shales is shown. Matrix anisotropy of shales dramatically increases with kerogen reaching the maximum values of about 0.4 at total organic carbon (TOC)=15–20%. A strong chemical softening effect was found in shales containing even minor amounts of swelling (smectite) clay when saturated with aqueous solution. This effect results in a significant P‐wave anisotropy reduction as compared to dry and oil‐saturated shales. Since mature black shales are normally oil wet, this effect can only have a local significance restricted to the wellbore wall. Accurate measurements of phase velocities, including velocities at a 45° direction to the bedding plane, allow us to immediately calculate elastic stiffnesses and anisotropic parameters. Intrinsic (high pressure) properties of shales display an ε > δ > 0 relation. Introduction of the bedding‐parallel microcracks in overpressured shales results in a δ decrease when fully fluid saturated and a δ increase when partially gas saturated, with a characteristic effect on the shape of the P‐wave velocity surface at small angles of incidence. Filtering the contribution of the intrinsic anisotropy of shales, it is possible to estimate the pore fluid phase, microcrack density, and aspect ratio parameters using seismic anisotropy measurements.
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Thèses sur le sujet "Anisotropy reduction"

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Jonsson, B. Lars G. « Directional Decomposition in Anisotropic Heterogeneous Media for Acoustic and Electromagnetic Fields ». Doctoral thesis, Stockholm : Tekniska högsk, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3099.

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Tezeghdanti, Walid. « Stratégie de réduction de modèle appliquée à un problème de fissuration dans un milieu anisotrope : application à la modélisation de la plasticité crystalline ». Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN006/document.

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Les aubes des turbines à haute pression des réacteurs d'avion subissent des chargements complexes dans un environnement réactif. Prédire leur durée de vie peut nécessiter une approche en tolérance aux dommages, basée sur la prédiction de la propagation d'une fissure supposée. Mais cette approche est confrontée au comportement non linéaire sous des chargements à amplitudes variables et au coût énorme des calculs elasto-plastiques des structures 3D complexes sur des millions des cycles. Dans ce cadre, un modèle incrémental de fissuration a été proposé. Ce modèle est basé sur la plasticité comme mécanisme principal de propagation de fissure par fatigue pure. Cette modélisation passe par une réduction de modèle de type POD. La plasticité en pointe de la fissure est alors modélisée par un nombre réduit de variables non locales et des variables internes. Un ensemble d'hypothèses doit être respecté pour garantir la validité de cette modélisation. Pour décliner ce modèle dans le cas d'un matériau anisotrope représentatif du comportement des monocristaux, une première étude a été faite sur le cas d'une élasticité cubique avec de la plasticité de Von-Mises. Une stratégie a été proposée pour identifier un modèle matériau basé sur les facteurs d'intensité non locaux. Cette stratégie comporte une détermination de la fonction critère basée sur les solutions élastiques en anisotrope. L'étude des directions d'écoulement plastique avec les variables non locales montre une forte dépendance à l'anisotropie élastique du modèle même avec une plasticité associée de Von-Mises. La stratégie comporte également une identification des variables internes.Dans la deuxième partie, le problème d'une fissure avec un modèle de plasticité cristalline a été traité. L'activation de différents systèmes de glissement a été alors prise en compte dans la modélisation. Finalement, différentes méthodologies ont été explorées en vue de transposer le modèle local de plasticité cristalline à l'échelle non locale de la région en pointe de la fissure
The fatigue life prediction of high pressure turbine blades may require a damage tolerance approach based on the study of possible crack propagation. The nonlinear behavior of the material under complex nonproportional loadings and the high cost of running long and expensive elastic-plastic FE computations on complex 3D structures over millions of cycles are some major issues that may encounter this type of approach.Within this context, an incremental model was proposed based on plasticity as a main mechanism for fatigue crack growth.A model reduction strategy using the Proper Orthogonal Decomposition (POD) was used to reduce the cost of FEA. Based on a set of hypotheses, the number of the degrees of freedom of the problem is reduced drastically. The plasticity at the crack tip is finally described by a set of empirical equations of few nonlocal variables and some internal variables.In order to apply this modeling strategy to the case of anisotropic materials that represent the behavior of single crystals, a first study was done with cubic elasticity and a Von-Mises plasticity. Elastic and plastic reference fields, required to reduce the model, were determined. Then, a material model of the near crack tip region was proposed based on nonlocal intensity factors. A yield criterion function was proposed based on Hoenig's asymptotic solutions for anisotropic materials. The study of plastic flow directions with the nonlocal variables of the model shows a strong dependency on the cubic elasticity. A strategy to identify internal variables is proposed as well. In the second part, a crystal plasticity model was implemented. The activation of different slip systems was taken into account in the model reduction strategy. A kinematic basis was constructed for each slip system. Finally, a strategy was proposed to transpose the local crystal plasticity model to the nonlocal scale of the crack
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Tran, Viviane. « Développement de polymères nanocomposites à propriété vitrimère par extrusion réactive : application à la diminution de l’anisotropie des propriétés mécaniques en impression 3D ». Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS251.pdf.

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L’impression 3D est un procédé de fabrication couche par couche qui permet de transformer une création réalisée par conception assistée par ordinateur (CAO) en un objet 3D tangible. Parmi les inconvénients majeurs de ce procédé, l’anisotropie des propriétés mécaniques, intrinsèque à la technique de fabrication additive qui conduit à une faible adhésion entre les couches et une porosité importante, limite drastiquement son utilisation à l’échelle industrielle. Les réseaux covalents dynamiques (CAN) sont une famille de matériaux dont les macromolécules sont réticulées par des liaisons dites réversibles. Parmi ces réseaux, les vitrimères sont généralement constitués de liaisons aux points de réticulation, qui activées par la température, suivent un mécanisme d’échange de type associatif. Ces réseaux chimiques ont des propriétés qui s’apparentent à celles des thermodurcissables ou des élastomères à température ambiante et qui peuvent être mis en forme comme les thermoplastiques par le contrôle des viscosités à une température plus élevée. Ils combinent donc a priori les avantages des polymères thermodurcis ou des élastomères sans leurs inconvénients : une bonne résistance thermique et chimique tout en étant recyclables et potentiellement imprimables en impression 3D de type dépôt de fil fondu (FDM). Ce manuscrit décrit un système de type polymère nanocomposite composé d’une matrice organique, un copolymère poly(éthylène acétate de vinyle) (EVA) réticulé avec des liaisons métal-ligands réversibles apportées par un précurseur oxo-alcoxyde de titane. En mettant à profit la propriété acide de Lewis de la composante inorganique des matériaux, en particulier via des réactions de transestérification activées sans ajout de catalyseur, par la température aux nœuds de réticulation du réseau, ces nouveaux polymères nanocomposites possèdent ainsi un comportement vitrimère. Après avoir décrit les systèmes hybrides organique-inorganique vitrimères étudiés, ce manuscrit se focalise sur l’élaboration des matériaux nanocomposites par extrusion réactive pour ensuite discuter de leur imprimabilité en FDM. Les paramètres de procédé ont été ajustés de façon à obtenir des vitrimères en une étape, de façon continue et à différentes concentrations en agents réticulant, par extrusion réactive. Ces derniers ont été caractérisés par des tests de gonflement, par DSC, DMTA et en rhéologie, la distribution de la composante inorganique au sein de la matrice organique a été mise en évidence par imagerie (MEB et MET). Par ailleurs, il a été démontré que ces polymères nanocomposites dynamiques sont imprimables et que la présence des points de réticulation réversibles permet une adhésion améliorée entre les filaments après traitement thermique. En effet, grâce au mécanisme d’échange associatif, l’objet imprimé conserve une bonne stabilité dimensionnelle sur une large gamme de températures ; un post-traitement thermique permet alors de favoriser l’adhésion des filaments, de diminuer le nombre et la taille des pores de façon concomitante avec la diffusion des macromolécules d’un filament à un autre, sans écoulement de la matière. Il en résulte une diminution de l’anisotropie des propriétés mécaniques qui a été déterminée par des tests de traction sur des échantillons imprimés dans deux orientations différentes
3D printing is a manufacturing process that enables the conversion of computer design into tangible 3D object by a layer-by-layer printing. One of the main drawbacks of this technique is the induced anisotropy of the mechanical properties caused by the weak interlayer bonds between printed layers and porosity. Covalent adaptable networks (CAN) are polymers bonded with reversible crosslinkers. Vitrimer is a new class of polymer among the CAN polymers in which crosslinking between the covalent networks is reversible owing to a thermally activated associative mechanism bond exchange. The network, thus, behaves like a thermoset or elastomer at room temperature but like a thermoplastic at higher temperature. The vitrimer has the advantages of both without their inconvenient: it has chemical and thermal resistance, can be recycled and can be theoretically printed by Fused Deposition Modeling (FDM) technique. This manuscript highlights a reversible metal-ligand bond nanocomposite EVA system, a polyethylene vinyl acetate copolymer crosslinked with an inorganic component brought by a titanium-oxo-alcoxo precursor. Thanks to reversible transesterification reaction at the crosslinking point, these new nanocomposite polymers lead to 3D permanent network with a vitrimer behavior. After defining this vitrimeric systeme, this manuscript focus on the synthesis of the vitrimer by continuous reactive extrusion and then on its printability in FDM. The process parameters for reactive extrusion had been adjusted in order to obtain materials with vitrimer properties proved by characterizations such as gel content, DSC, DMTA or rheology. Moreover, we demonstrated that such dynamic polymer nanocomposites can be printable and can reinforce the interlayer bonds between two printed layers thanks to the introduced reversible bonds that are activated by the rise of temperature. Following an associative mechanism, there is no loss of the dimensional stability upon reheating the printed object so thermal treatment can be used to enhance the diffusion of macromolecules from one layer to the other layer without loss of the integrity of the network. Thus, after thermal treatment, porosity of the printed sample decreases in number and in size leading to smaller anisotropy of the mechanical properties which are measured with tensile test of samples printed in two different directions
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Traforti, Anna. « Reactivated fault zones : kinematic complexity and fault rock spectral characterization ». Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3421819.

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In the present work three main factors contributing to the overall complexity of reactivated fault zones have been investigated: i) the problematic reconstruction of polyphase brittle tectonic evolution accommodated by fault zones dissecting lithologically heterogeneous rock domains; ii) the estimate of the mechanical anisotropy associated with pre-existing planar discontinuities (i.e., metamorphic foliations and inherited faults) steering their brittle reactivation process; iii) the spectral characterization of fault zone rocks in complex fault architectures aimed at inferring the distribution of fault zone domains by means of remote sensing techniques. In order to achieve the goal of improving current understanding of these factors defining reactivated fault zone complexity, different methodologies have been applied: i) a paleostress inversion analysis that carefully considers each analyzed fault zones and the different mechanical behavior of the lithological domains they deform; ii) a bootstrapping statistical approach aimed at evaluating the homogeneity between the resulting stress tensors and identifying possible local stress perturbations; iii) a normalised slip tendency analysis that, integrated with paleostress reconstructions and detailed meso- and micro-structural observations, allows constraining the mechanical properties of pre-existing planar discontinuities; iv) a spectral features analysis of fault zone rock reflectance spectra, aimed at highlighting the correlation between variations in fault rock spectral signatures and grain size reduction related to fault comminution processes. The main results of this work highlighted that: i) polyphase brittle tectonics within lithologically heterogeneous rock domains can be efficiently unrevealed by applying a paleostress inversion combined with bootstrapping statistical analysis of the resulting reduced stress tensors; ii) normalised slip tendency analysis can be considered a reliable method to investigate and constrain the weakness of pre-existing anisotropies at a regional scale (104-103 m); iii) the grain size reduction resulting from fault-related comminution processes on mineralogically homogenous bedrocks (carbonates in this case) influences the spectral signatures of fault rock samples, which absorption feature parameters vary systematically with the grain size in the VNIR and SWIR wavelength ranges; iv) consequently, remote sensing analysis, based on fault rock reflectance spectrum variabilities due to comminution processes, has a good potential in the identification of the spatial distribution and extent of fault core and damage zone domains (i.e., characterized by different grain sizes) on mineralogically homogenous bedrocks (carbonates in this case).
Nel presente lavoro sono stati investigati tre fattori che contribuiscono alla definizione della complessità delle zone di faglia riattivate: i) la ricostruzione dell’evoluzione tettonica polifasica accomodata da zone di faglia che interessano litologie eterogenee; ii) la stima del grado di anisotropia meccanica associata alla presenza di discontinuità planari pre-esistenti (i.e., foliazioni metamorfiche e faglie), il quale influenza i meccanismi di riattivazione lungo tali piani; iii) la caratterizzazione spettrale delle rocce di faglia, finalizzata all’ identificazione della distribuzione delle zone di danno e di core tramite tecniche di remote sensing, con particolare riguardo a zone di faglie mature aventi un’architettura complessa. Al fine di dare un nuovo contributo alla comprensione dei fattori che definiscono le complessità insite nelle zone di faglia riattivate, sono state applicate diverse metodologie che comprendono: i) l’inversione del campo di paleostress, applicata considerando il comportamento meccanico dei domini litologici interessati da ogni differente zona di faglia; ii) l’approccio statistico di tipo ‘bootstrapping’ applicato al fine di valutare l’omogeneità tra i tensori di stress ricavati e di identificare possibili perturbazioni locali del campo di paleostress; iii) la ‘normalised slip tendensy analysis’ che, integrata alla ricostruzione del campo di paleostress e ad una caratterizzazione di tipo micro- e meso-strutturale, permette di stimare quantitativamente le proprietà meccaniche di discontinuità planari pre-esistenti; iv) l’analisi delle bande di assorbimento osservate negli spettri di riflettenza di diverse rocce di faglia, al fine di evidenziare il rapporto esistente tra le variazioni osservate nei parametri spettrali e i processi di comminuzione dovuti all’evolversi della zona di faglia stessa. I principali risultati di questo lavoro evidenziano come: i) tettoniche polifasiche che si sviluppano in domini rocciosi altamente eterogenei possono essere efficacemente ricostruite applicando in maniera integrata l’inversione del campo di paleostress e l’analisi statistica di tipo ‘bootstrapping’; ii) la ‘normalised slip tendency analysis’ permette di investigare la debolezza di anisotropie pre-esistenti a scala regionale (104-103 m); iii) la riduzione granulometrica connessa ai processi di comminuzione dovuti all’evolversi di una zona di faglia in rocce incassanti omogenee dal punto di vista mineralogico (carbonati in questo caso) influenza la firma spettrale delle rocce di faglia, le cui bande di assorbimento hanno caratteristiche che variano sistematicamente con la diminuzione della granulometria; iv) di conseguenza, l’analisi in remoto, basata sugli effetti della comminuzione sulle firme spettrali delle rocce di faglia, dimostra un buon potenziale nell’identificazione della distribuzione spaziale delle zone di danno e di core di una faglia in rocce incassanti omogenee dal punto di vista mineralogico.
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Dieulangard, Anthony. « Nouvelles configurations d'interaction pour l'optimisation conjointe des performances des composants acouto-optiques ». Thesis, Valenciennes, 2014. http://www.theses.fr/2014VALE0027/document.

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Une description des différentes configurations d’interaction ayant lieu dans les matériaux usuellement employés dans le domaine acousto-optique est proposée. Un exemple d’application illustre les caractéristiques déterminantes propres à chaque fonction que permet l’interaction acousto-optique, à savoir la modulation, la déviation, le décalage en fréquence et le filtrage d’un faisceau optique. Cette thèse est plus particulièrement consacrée aux interactions acousto-optiques anisotropes dans le cristal de Paratellurite, matériau majoritairement employé pour les applications de déflexion et de filtrage de par ses qualités photo-élastiques remarquables et son large domaine de transparence optique. Ces propriétés optiques, acoustiques et acousto-optiques sont décrites en détail. Nous nous intéressons plus particulièrement aux caractéristiques de l’interaction NPM (Narrow Phase Mismatch) et TPM (Tangent Phase Mismatch), respectivement employées pour le filtrage et la déflexion. Ceci nous conduit à l’étude de la bande passante spectrale d’un déflecteur et de sa potentielle application en tant que réseau de diffraction à bande passante et périodicité spatiale modulable. Ensuite nous proposons la mise en cascade d’un déflecteur et d’un filtre dans le but de concevoir un décaleur de fréquence variable à faible décalage. Enfin, nous proposons une configuration originale pour répondre aux contraintes d’utilisation rencontrées avec l’interaction NPM pour les applications de filtrage. La conception et la réalisation d’un composant multiélectrodes à interaction double est alors présentée dans la gamme spectrale [400; 650 nm]. La configuration proposée permet à la fois de réduire de 50% l’intensité des lobes secondaires tout en homogénéisant la bande passante optique du filtre sur sa bande spectrale de travail
The different configurations of acousto-optic interactions taking place in usual employed materials are presented. For each function (modulation, deflection, shifting and filtering), an exemple of application highlights the decisive characteristics of the component. This thesis is particularly devoted to the anisotropic interactions occuring in Paratellurite crystal. Such material is widely used for filtering and deflection applications due to its high figure of merit and also for its large optical transparency domain, from Ultra-Violet to Infra-Red. Optical, acoustical and acoustooptical properties of Paratellurite cristal are detailed. More precisely, we are interested in anisotropic interactions, in particular NPM (Narrow Phase Mismatch) and TPM (Tangent Phase Mismatch), respectively employed for Acousto-Optic Tunable Filters (AOTF) and Acousto-Optic Deflectors (AOD). This leads to the study of the optical bandwidth of a deflector with a potential application as a tunable transmissive grating beam splitter for multiple laser line separation. Then, we propose to cascade an AOTF with an AOD in order to get a wide bandwidth tunable optical low frequency shifter. Finally, we present the design and fabrication of a multi-transducer component based on dual anisotropic interaction in the visble spectral range, from 400 to 650 nm. A significative reduction of sides lobes is observed (-50%) with an homogenisation of the optical bandwidth of the filter on its spectral working range
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Coble, Kimberly Ann. « Data reduction and analysis of the Python V cosmic microwave background anisotropy experiment / ». 1999. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:9951776.

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Vogt, Björn [Verfasser]. « Reduction of quantum fluctuations by anisotropy fields in Heisenberg ferro- and antiferromagnets / Björn Vogt ». 2009. http://d-nb.info/996407685/34.

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Chapitres de livres sur le sujet "Anisotropy reduction"

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Verstraeten, G. J. M. « Thermodynamical reduction of the anisotropy of time by introducing irreversibility on microscopical scale ». Dans The Physics of Phase Space Nonlinear Dynamics and Chaos Geometric Quantization, and Wigner Function, 438–40. Berlin, Heidelberg : Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/3-540-17894-5_403.

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Lee, Hunju, et Jong-Tae Park. « Effect of Cold Rolling Reduction on Recrystallization Texture and Magnetic Anisotropy of Non-Oriented Electrical Steel ». Dans Proceedings of the 6th International Conference on Recrystallization and Grain Growth (ReX&GG 2016), 185–89. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48770-0_27.

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Lee, Hunju, et Jong-Tae Park. « Effect of Cold Rolling Reduction on Recrystallization Texture and Magnetic Anisotropy of Non-Oriented Electrical Steel ». Dans Proceedings of the 6th International Conference on Recrystallization and Grain Growth (ReX&GG 2016), 185–89. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2016. http://dx.doi.org/10.1002/9781119328827.ch27.

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Khoromskij, Boris N., et Gabriel Wittum. « Robust Interface Reduction for Highly Anisotropic Elliptic Equations ». Dans Lecture Notes in Computational Science and Engineering, 140–56. Berlin, Heidelberg : Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-642-58734-4_8.

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Noor, A. K. « Reduction Method for the Nonlinear Analysis of Symmetric Anisotropic Panels ». Dans Finite Element Methods for Nonlinear Problems, 389–407. Berlin, Heidelberg : Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-82704-4_21.

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Gavgani, A. Mazloumi, et Y. Serinagaoglu Dogrusoz. « Noise Reduction Using 2D Anisotropic Diffusion Filter in Inverse Electrocardiography ». Dans IFMBE Proceedings, 505–8. Cham : Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-00846-2_125.

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Shoaib, Muhammad Ali, Joon Huang Chuah, Azira Khalil, Muhammad Hanif Ahmad Nizar et Khin Wee Lai. « Anisotropic Diffusion for Reduction of Speckle Noise in Knee Articular Cartilage Ultrasound Images ». Dans IFMBE Proceedings, 46–53. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-65092-6_5.

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Sun, Li-mei, Wei Qiao, Meng-lu Han, Xiao-wei Guan et Peng Zhang. « Research and Application of Anisotropic Prestack Inversion Technology Based on OVT Domain Dimension Reduction in Fracture Prediction-Taking Shahezi Formation of Dsh20 Well Area in Anda Area of Northern Songliao Basin as an Example ». Dans Springer Series in Geomechanics and Geoengineering, 251–62. Singapore : Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-97-0483-5_26.

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Hiremath, Shilpa, et A. Shobha Rani. « Image Filtering Using Anisotropic Diffusion for Brain Tumor Detection ». Dans Applications of Parallel Data Processing for Biomedical Imaging, 244–60. IGI Global, 2024. http://dx.doi.org/10.4018/979-8-3693-2426-4.ch012.

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Brain tumor analysis is a critical aspect of medical applications, offering valuable structural and functional insights crucial for disease diagnosis. Early detection of tumors significantly enhances treatment outcomes and patient survival rates. However, the manual segmentation of numerous magnetic resonance images poses challenges due to the increased risk of human error. Therefore, there is a pressing need for computer-aided detection systems to ensure higher accuracy and faster tumor identification. In our work, we propose computer-aided techniques utilizing anisotropic diffusion filtering, Otsu threshold segmentation, and morphological procedures for noise reduction, segmentation, and tumor area detection in MR images. Our approach aims to streamline the process of tumor identification by automating key steps through advanced image processing methods. Notably, simulation results highlight the superiority of anisotropic diffusion and Otsu thresholding over other filtering and segmentation combinations, underscoring their effectiveness in enhancing tumor detection accuracy.
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Pavithra D., Vanithamani R. et Judith Justin. « Computer-Aided Diagnosis of Knee Osteoarthritis From Radiographic Images Using Random Forest Classifier ». Dans Research Anthology on Improving Medical Imaging Techniques for Analysis and Intervention, 1398–414. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-7544-7.ch071.

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Knee osteoarthritis (OA) is a degenerative joint disease that occurs due to wear down of cartilage. Early diagnosis has a pivotal role in providing effective treatment and in attenuating further effects. This chapter aims to grade the severity of knee OA into three classes, namely absence of OA, mild OA, and severe OA, from radiographic images. Pre-processing steps include CLAHE and anisotropic diffusion for contrast enhancement and noise reduction, respectively. Niblack thresholding algorithm is used to segment the cartilage region. GLCM features like contrast, correlation, energy, homogeneity, and cartilage features such as area, medial, and lateral thickness are extracted from the segmented region. These features are fed to random forest classifier to assess the severity of OA. Performance of random forest classifier is compared with ANFIS and Naïve Bayes classifier. The classifiers are trained with 120 images and tested with 45 images. Experimental results show that random forest classifier achieves a higher accuracy of 88.8% compared to ANFIS and Naïve Bayes classifier.
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Actes de conférences sur le sujet "Anisotropy reduction"

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Woo, C. H. « State reduction and cosmic anisotropy ». Dans After the first three minutes. AIP, 1991. http://dx.doi.org/10.1063/1.40442.

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Junqueira, Mateus A. F. C., Lucas H. Gabrielli et Danilo H. Spadoti. « Anisotropy Reduction Strategies for Transformation Optics Designs ». Dans Latin America Optics and Photonics Conference. Washington, D.C. : OSA, 2014. http://dx.doi.org/10.1364/laop.2014.lm4a.1.

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Junqueira, Mateus A. F. C., Lucas H. Gabrielli et Danilo H. Spadoti. « Parameterization strategy for anisotropy reduction in the carpet cloak ». Dans 2015 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC). IEEE, 2015. http://dx.doi.org/10.1109/imoc.2015.7369076.

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Hales, Alistair, Lorna J. Ayton, Roman Kisler, Ahmed Mahgoub, Chaoyang Jiang, Rowena Dixon, Charitha de Silva, Danielle Moreau et Con J. Doolan. « Reduction of Leading-Edge Noise by Tailored Turbulence Anisotropy ». Dans 28th AIAA/CEAS Aeroacoustics 2022 Conference. Reston, Virginia : American Institute of Aeronautics and Astronautics, 2022. http://dx.doi.org/10.2514/6.2022-3046.

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Wiese, D., et M. Breitwieser. « Reduction of the 2F-Vibrations of Simple Flexible Rolls by Partial Machining ». Dans ASME 1999 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/detc99/vib-8281.

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Abstract In paper and foil production plant, roll vibrations occurring at twice the rotational frequency often present serious problems. These are caused by anisotropy of roll stiffness — referred to below as stiffness anisotropy. In the past the reduction of this stiffness anisotropy was impossible. When vibrations occurring at twice the frequency of rotation became too high, the entire roll had to be scrapped. This paper deals with a method for the identification of the anisotropy of rotor stiffness on a balancing machine. If the stiffness anisotropy is known, vibrations occurring at twice the frequency of rotation can be systematically reduced to a tolerable level by partial machining of the roll.
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Huai, Xiaoning, Kijong Lee et Chaesung Kim. « Image noise reduction by dynamic thresholding of correlated wavelet intensity and anisotropy ». Dans 2010 International SoC Design Conference (ISOCC 2010). IEEE, 2010. http://dx.doi.org/10.1109/socdc.2010.5682982.

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Dhifallah, Chaima, Nejeh Hamdaoui, Sami Ameur et Ridha Ajjel. « The impact of electrodes on the reduction of anisotropy in biological tissue ». Dans 2021 18th International Multi-Conference on Systems, Signals & Devices (SSD). IEEE, 2021. http://dx.doi.org/10.1109/ssd52085.2021.9429393.

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Semenikhin, A. I., D. V. Semenikhina, Y. V. Yukhanov et P. V. Blagovisnyy. « Digital 2-bit metasurfaces with coding orientation of anisotropy for RCS reduction ». Dans 2017 International Conference on Electromagnetics in Advanced Applications (ICEAA). IEEE, 2017. http://dx.doi.org/10.1109/iceaa.2017.8065250.

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Xu, Ping, Ling-Yun Fang et Zhi-Jun Sun. « Research on Limit Equilibrium Analysis Method of Loess Slope Considering Cross-anisotropy ». Dans 2021 7th International Conference on Hydraulic and Civil Engineering & Smart Water Conservancy and Intelligent Disaster Reduction Forum (ICHCE & SWIDR). IEEE, 2021. http://dx.doi.org/10.1109/ichceswidr54323.2021.9656329.

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Olson, Brandon, et Samuel Graham. « Extending the 3 Omega Method to Measure Thermal Conductivity Anisotropy in Three Dimensions ». Dans ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72509.

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A simplified method of measuring three-dimensional thermal conductivity anisotropy has been developed around the popular 3ω method. This approach utilizes a pair of surface mounted test elements as both heating and sensing probes. 3ω has historically been used to measure thermal conductivity in homogeneous, low conductivity substrates and thin surface films. The present technique employs a combination of broad band frequency measurements and directionally oriented test elements to extract property information that was previously inaccessible. Data reduction is dramatically improved through the use of a full accuracy analytical solution that replaces the heavily approximated original 3ω solution. Anisotropic degrees of freedom are optimized using an efficient gradient based algorithm that can be coded using any number of commercially available software packages. Test element design guidelines are presented to help insure that optimal experimental conditions exist during material testing. Comparative experimental results are presented for an aligned graphite fiber / epoxy composite.
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