Journal articles: 'Anisotropy reduction'

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Grudinin, Dmitriy, Olga Matveeva, Georgy Ermolaev, Andrey Vyshnevyy, Aleksey Arsenin, and Valentyn Volkov. "Reduction in Crosstalk between Integrated Anisotropic Optical Waveguides." Photonics 10, no. 1 (January 5, 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, and 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 (June 5, 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, and F. DURST. "Interpretation of the mechanism associated with turbulent drag reduction in terms of anisotropy invariants." Journal of Fluid Mechanics 577 (April 19, 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, and T. A. Witten. "Anisotropy in turbulent drag reduction." Physical Review Letters 65, no. 22 (November 26, 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, and Haemyeong Jung. "Twin Induced Reduction of Seismic Anisotropy in Lawsonite Blueschist." Minerals 11, no. 4 (April 10, 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, and Julianna Simon. "Histotripsy bubble dynamics in tendon and anisotropic gel phantoms." Journal of the Acoustical Society of America 151, no. 4 (April 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 (November 1, 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, and Han Dong. "Microstructure, Texture, and Anisotropic Properties of High-Strength Low-Alloy Steel." Coatings 13, no. 8 (August 16, 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, and 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 (February 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, and Xingzhou Liu. "Velocity anisotropy in shales: A petrophysical study." GEOPHYSICS 62, no. 2 (March 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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Yu, Gengfeng, Chao Yu, Zunan Fu, Jianguo Jing, Zheng Hu, and Kun Pan. "Mechanical Consequences of Suffusion on Gap-Graded Soils with Stress Anisotropy: A CFD–DEM Perspective." Buildings 14, no. 1 (January 2, 2024): 122. http://dx.doi.org/10.3390/buildings14010122.

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Natural soil in geotechnical engineering is commonly in the anisotropic stress state, but the effect of stress anisotropy on soil suffusion remains unclear. In this study, the coupled computational fluid dynamics–discrete element method was utilised to simulate the complete suffusion process of gap-graded soils by introducing a vertical seepage flow through the soil assembly. The mechanical consequences of suffusion on gap-graded soils were evaluated by comparing the triaxial shear responses of soil specimens before and after suffusion. The results indicated that the specimens with greater stress anisotropy are more vulnerable to suffusion, particularly those with the principal stress that is coincident with the principal flow direction. Compared with the isotropically consolidated specimens, the specimens with greater stress anisotropy exhibited more pronounced reduction in shear strength and secant stiffness after suffusion. The effects of stress anisotropy on the suffusion and mechanical properties of gap-graded soils were also evaluated from a microcosmic perspective in terms of force chain, coordination number, and fabric tensor.

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Kim, Min-Soo, Min-Ji Shin, Akshay Kumar, Kavita Kumari, Seok-Hwan Huh, and Bon-Heun Koo. "Unravelling the Anisotropic Behavior of Nickel—Wires Prepared through External Magnetic Field Assisted Hydrazine Reduction Method." Applied Sciences 11, no. 18 (September 16, 2021): 8627. http://dx.doi.org/10.3390/app11188627.

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Ni wires, prepared through a hydrazine reduction, were exposed to external magnetic fields of different geometrical shape and configuration during the synthesis denoted as Ni-Non-Magnetic, Ni-Double, Ni-Single, Ni-Ring. Their effect on the wire morphology, magnetization and magnetic anisotropy was then investigated via various characterization techniques viz. X-ray diffraction (XRD), high-resolution field emission scanning electron microscopy (HR-FESEM), and vibrating sample magnetometer (VSM). The polycrystalline single phase of the Ni-wires with face centered cubic symmetry was confirmed through the analysis of XRD patterns. Analysis of HR-FESEM images revealed that the Ni-particles were aligned in form of wire-like morphology. The Ni-single sample formed the wires with minimum diameter compared to the parent sample. The magnetization measurements performed at 300 K and 50 K demonstrated the ferromagnetic behavior of all the samples. The room temperature saturation magnetization (MS) and anisotropy constant (K) of the Ni-wires were reduced upon providing the external field during synthesis. However, the low temperature (50 K) magnetization behavior was rather opposing, indicating enhanced values of MS and K. Among all, Ni-ring sample showed maximum anisotropy with a value of 3.84 × 104 erg/cm3 at 50 K. The ambiguous nature of the anisotropic constant and saturation magnetization ascribed partly to the variation in diameters of Ni-wires and to the intermittent spin-spin exchange interactions of unaligned/partially aligned particles during the synthesis. Briefly, in the present study, it was established that the morphology and magnetic anisotropy of the Ni-wires could be tailored through the external magnetic field assisted synthesis method.

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Shi, Zhijun, Wei Shao, Lixiang Rao, Xiaolei Xing, Yefei Zhou, Xuejun Ren, and Qingxiang Yang. "Pressure-induced structure, elasticity, intrinsic hardness and ideal strength of tetragonal C₄N." Physical Chemistry Chemical Physics 24, no. 8 (2022): 5171–84. http://dx.doi.org/10.1039/d1cp05163f.

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The novel t-C4N predicted via CALYPSO could be a potential superhard material, with pressure-induced hardness reduction, mechanical properties and anisotropy increase. The hardness reduction is related to anisotropy increase.

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Zahn, Anna, and Daniel Balzani. "MODELING OF ANISOTROPIC GROWTH AND RESIDUAL STRESSES IN ARTERIAL WALLS." Acta Polytechnica CTU Proceedings 7 (December 9, 2016): 85. http://dx.doi.org/10.14311/app.2017.7.0085.

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Based on the multiplicative decomposition of the deformation gradient, a local formulation for anisotropic growth in soft biological tissues is formulated by connecting the growth tensor to the main anisotropy directions. In combination with an anisotropic driving force, the model enables an effective stress reduction due to growth-induced residual stresses. A method for the imitation of opening angle experiments in numerically simulated arterial segments, visualizing the deformations related to residual stresses, is presented and illustrated in a numerical example.

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Stepanenko, A. V. "Study of the anisotropy of the polycrystal properties based on texture data." Industrial laboratory. Diagnostics of materials 85, no. 9 (September 28, 2019): 46–51. http://dx.doi.org/10.26896/1028-6861-2019-85-9-46-51.

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The results of studying correlation between the crystallographic texture of polycrystalline materials and anisotropy of their physical and mechanical properties are considered. The methods for calculating the anisotropic properties of polycrystals based on the data obtained by X-ray methods of direct and inverse pole figures are reviewed. Calculation methods based on the use of the distribution function of crystallite orientations require the use of a large amount of experimental data and, hence, they are not suitable for express estimation of the anisotropy level of the physical properties of samples upon their thermomechanical processing. A method for rapid estimation of the anisotropic properties of the sample based on the use of Д; ("orientation factors") in the calculations, is proposed. Experimental data of X-ray analysis (method of inverse pole figures) are used to calculate the absolute and relative deviations of the physical parameter of textured polycrystal from the same value in the isotropic sample. The contributions of individual crystallographic orientations to the formation of the anisotropy of the properties of the sample are estimated. The dynamics of quantitative changes in the anisotropic properties of a polycrystal in the process of texture formation is studied. To analyze the source of the most rapid changes in the anisotropy of properties, we used the coefficients of the "response" matrix, the calculation of which does not depend on the results of specific diffractometric measurements, but is common for all metals with a hexagonal close-packed (hep) lattice. The anisotropy of the coefficient of thermal conductivity, electrical conductivity, and thermal diffusivity was calculated for the samples of deformed yttrium which underwent cold rolling with a reduction ratio of e = 25%. It is shown that the final physical properties_of the hep polycrystal are largely determined by the pyramidal crystallographic orientations {1015}, {1124}. The results of the study form a basis for analysis of the anisotropy of the physical properties of hep-metal samples upon thermomechanical processing.

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Grechnikov, F. V., Ya A. Erisov, S. V. Surudin, and V. A. Razzhivin. "Effect of reduction ratio during cold rolling and final annealing temperature on the properties and microstructure of Al–Mg–Sc alloy sheets." Izvestiya Vuzov. Tsvetnaya Metallurgiya (Universities' Proceedings Non-Ferrous Metallurgy) 28, no. 4 (August 19, 2022): 75–83. http://dx.doi.org/10.17073/0021-3438-2022-4-75-83.

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The study covers the effect of the reduction ratio during cold rolling (εh) and the final annealing temperature of sheets rolled with different reduction ratios on the microstructure and the complex of mechanical and processing properties of cold-rolled sheets made of the V-1579 aluminum alloy of the Al–Mg–Sc system. It was established that as εh increases, the nature of plastic anisotropy changes slightly, and an increase in tensile strength and yield strength with a decrease in relative elongation is observed. In this case, the ultimate strength and yield strength anisotropy is practically absent. As the reduction ratio increases to 30–40 %, the relative elongation anisotropy increases, and its value in the rolling direction decreases more rapidly. However, after rolling with εh > 50 %, the relative elongation anisotropy practically disappears. Regardless of the annealing temperature, samples rolled with a higher reduction ratio have better strength properties. It was found that as the annealing temperature increases, the ultimate strength and yield strength decrease, and the relative elongation increases. In this case, softening with an increase in the annealing temperature occurs more intensively for samples rolled with a lower reduction. After annealing, the distribution nature of anisotropy indices in the sheet plane does not decrease and corresponds to the deformation type of textures for all analyzed modes. Moreover, the value of the in-plane anisotropy coefficient decreases in comparison with a cold-rolled sample. At the same time, processing properties of samples rolled with a higher degree of deformation after annealing are higher than those of samples rolled with a lower reduction, regardless of the annealing temperature.

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Ghorbanalilu, Mohammad, and Elahe Abdollahazadeh. "Extension of temperature anisotropy Weibel instability to non-Maxwellian plasmas by 2D PIC simulation." Laser and Particle Beams 36, no. 1 (December 29, 2017): 1–7. http://dx.doi.org/10.1017/s0263034617000842.

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AbstractThe Weibel instability driven by temperature anisotropy is investigated in a two-dimensional (2D) particle-in-cell simulation in non-extensive statistics in the relativistic regime. In order to begin the simulation, we introduced a new 2D anisotropic distribution function in the context of non-extensive statistics. The heavy ions considered to be immobile and form the neutralizing background. The numerical results show that non-extensive parameterqplays an important role on the magnetic field saturation time, the time of reduction temperature anisotropy, evolution time to the quasi-stationary state, and the peak energy density of magnetic field. We observe that the instability saturation time increases by increasing the non-extensive parameterq. It is shown that structures with superthermal electrons (q< 1) could generate strong magnetic fields during plasma thermalization. The simulation results agree with the previous simulations for an anisotropic Maxwellian plasma (q= 1).

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Song, Honghua, Yixin Zhao, Yaodong Jiang, and Jiehao Wang. "Scale Effect on the Anisotropy of Acoustic Emission in Coal." Shock and Vibration 2018 (December 18, 2018): 1–11. http://dx.doi.org/10.1155/2018/8386428.

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Acoustic emission (AE) in coal is anisotropic. In this paper, we investigate the microstructure-related scale effect on the anisotropic AE feature in coal at unconfined loading process. A series of coal specimens were processed with diameters of 25 mm, 38 mm, 50 mm, and 75 mm (height to diameter ratio of 2) and anisotropic angles of 0°, 15°, 30°, 45°, 60°, and 90°. The cumulative AE counts and energy dissipation increase with the specimen size, while the energy dissipation per AE count behaves in the opposite way. This may result from the increasing amount of both preexisting discontinuities and cracks (volume/number) needed for specimen failure and the lower energy dissipation AE counts generated by them. The effect of microstructures on the anisotropies of AE weakens with the increasing specimen size. The TRFD and its anisotropy reduce as the specimen size increases, and the reduction of fractal dimension is most pronounced at the anisotropic angle of 45°. The correlation between TRFD and cumulative AE energy in the specimens with different sizes are separately consistent with the negative exponential equation proposed by Xie and Pariseau. With the specimen size gain, the reduction of the TRFD weakens with the increasing amount of cumulative absolute AE energy.

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Yeo, K. S. "The hydrodynamic stability of boundary-layer flow over a class of anisotropic compliant walls." Journal of Fluid Mechanics 220 (November 1990): 125–60. http://dx.doi.org/10.1017/s0022112090003214.

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This paper examines the linear stability of zero-pressure-gradient boundary-layer flow over a class of anisotropically responding compliant walls. The anisotropic wall behaviour is derived from a material anisotropy which is characterized by relatively high tensile and compressive strength along a certain direction, termed the fibre axis. When the material stiffness along the fibre axis is sufficiently high, the resulting correlation between the horizontal and the vertical components of wall displacement induces at the flow–wall interface a Reynolds shear stress of a sign that is predetermined by the angle with which the fibre axis makes with the direction of the flow. The notion that anisotropic surface response could be employed to produce turbulent Reynolds shear stresses of predetermined sign at a surface was first explored by Grosskreutz (1971) in an experimental study on turbulent drag reduction. The present paper examines the implications of this interesting idea in the context of two-dimensional flow stability over anisotropic compliant walls. The study covers single- and two-layer compliant walls using the methodology described in Yeo (1988). The effects of wall anisotropy, as determined by the orientation of the fibre axis and the material stiffness along the fibre axis, on flow stability are examined for a variety of walls. The potential of some anisotropic compliant walls for delaying laminar–turbulent transition is investigated, and the contribution of the anisotropy to transition delay is appraised.

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Grechka, Vladimir, and Sergey Yaskevich. "Azimuthal anisotropy in microseismic monitoring: A Bakken case study." GEOPHYSICS 79, no. 1 (January 1, 2014): KS1—KS12. http://dx.doi.org/10.1190/geo2013-0211.1.

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Hydraulic fracturing, routinely applied for enhancing the permeability of unconventional oil and gas reservoirs, is one of the possible causes for azimuthal anisotropy of the treated formations. Accounting for both naturally occurring and completion induced azimuthal anisotropy leads to marked improvements in the results of microseismic data processing. As illustrated on a data set acquired in the Bakken Field, North Dakota, USA, those improvements include the possibility of modeling the observed shear-wave splitting, reduction of misfit between the picked and modeled traveltimes of microseismic events, and relocation and tightening of the spatial distribution of the event hypocenters. In addition and perhaps most importantly for the development of microseismic technology, the feasibility of joint inversion of field microseismic data for the event locations and azimuthally anisotropic velocity model containing triclinic layers is demonstrated.

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Delabrouille, Jacques. "Issues and methods for CMB anisotropy data reduction." New Astronomy Reviews 45, no. 4-5 (March 2001): 313–20. http://dx.doi.org/10.1016/s1387-6473(00)00153-6.

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Senuma, Takehide, and Natsuko Hashimoto. "Influence of Grain Refinement of Hot Band and Cold Rolling Reduction on the Formation of Textures and R-Value of Cold Rolled Plain Extralow-Carbon Steel Sheets." Textures and Microstructures 30, no. 1-2 (January 1, 1997): 97–123. http://dx.doi.org/10.1155/tsm.30.97.

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A textural analysis was carried out to explain the cause of the planar anisotropy of r-value of cold rolled plain extralow-carbon steel sheets. For a detailed analysis, a model for calculating r-values from ODF-data of texture was applied and the influence of each or a group of crystal orientations of the recrystallization texture on the planar anisotropy of r-values was studied. The following results were obtained:A development of {111}〈110〉−{443}〈110〉−{332}〈110〉−{221}〈110〉 enhanced the V-type planar anisotropy of r-values. A decrease in the intensity of these orientations by increasing the cold rolling reduction or the refinement of the hot band microstructure reduced the r-values in L and C directions and hardly affected the r-value in D direction, and as a result, the V-type planar anisotropy of r-values was improved. On the other hand, an increase in the intensity of {111}, {334} orientation by increasing the cold rolling reduction or the refinement of the hot band microstructure raised r-values in sequence of L < D < C directions and contributed to the reduction of V-type planar anisotropy of r-values as a whole.

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Plummer, Christopher J. G., Hans-Henning Kausch, Yujun Wu, and Muzio Gola. "The Long Term Mechanical Behaviour of Filled and Unfilled Injection Moulded Thermotropic Liquid Crystalline Polymers." Engineering Plastics 2, no. 5 (January 1994): 147823919400200. http://dx.doi.org/10.1177/147823919400200505.

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Injection mouldings of thermotropic liquid crystalline polymers (TLCPs) have complex, highly anisotropic layered structures, and correspondingly large spatial variations in orientation and mechanical properties. The room temperature axial mechanical properties of standard tensile test specimens moulded from TLCPs are remarkable (ten-fold and two-fold increases in modulus and strength respectively, compared with conventional resins). Nevertheless, in practice glassfibre or mineral fillers are recommended to overcome problems associated with the anisotropy of unfilled TLCP mouldings, such as warping. The resulting reduction of anisotropy and more uniform local properties are not found to compromise seriously the axial mechanical properties, and indeed may improve both the short and the long-term behaviour, depending on the moulding conditions. Short glass-fibre addition appears particularly beneficial for the creep and fatigue resistance.

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Plummer, Christopher J. G., Hans-Henning Kausch, Yujun Wu, and Muzio Gola. "The Long Term Mechanical Behaviour of Filled and Unfilled Injection Moulded Thermotropic Liquid Crystalline Polymers." Polymers and Polymer Composites 2, no. 5 (January 1994): 307–16. http://dx.doi.org/10.1177/096739119400200505.

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Injection mouldings of thermotropic liquid crystalline polymers (TLCPs) have complex, highly anisotropic layered structures, and correspondingly large spatial variations in orientation and mechanical properties. The room temperature axial mechanical properties of standard tensile test specimens moulded from TLCPs are remarkable (ten-fold and two-fold increases in modulus and strength respectively, compared with conventional resins). Nevertheless, in practice glassfibre or mineral fillers are recommended to overcome problems associated with the anisotropy of unfilled TLCP mouldings, such as warping. The resulting reduction of anisotropy and more uniform local properties are not found to compromise seriously the axial mechanical properties, and indeed may improve both the short and the long-term behaviour, depending on the moulding conditions. Short glass-fibre addition appears particularly beneficial for the creep and fatigue resistance.

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Zhang, Gong Ting, Zhi Wang Zheng, and Jun Chang. "Effect of Coiling Temperature and Cold Rolling Reduction on Planar Anisotropy of Ti-Alloyed Low Carbon Steel." Applied Mechanics and Materials 576 (June 2014): 161–65. http://dx.doi.org/10.4028/www.scientific.net/amm.576.161.

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The effects of coiling temperature and cold rolling reduction on planar anisotropy of Ti-alloyed low carbon steel were investigated. The results show that as the coiling temperature increases from 509°C to 633°C, the strength and elongation have little change, and the planar anisotropy trends to decrease. When coiling at 580°C to 640°C, the value of planar anisotropy index (△r) can be reduced to no more than 0.15. As the total cold rolling reduction increasing from 55% to 85%, the plastic strain ratio values (r-values) perpendicular to rolling direction increase firstly, then decrease; the change regulation of rolling direction is reverse, and the values of 45°direction nearly have no change. And the planar anisotropy can reach 0.07 as cold rolling at 75%.

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Wan, Wei, Changxin Tang, Jianjie Zhang, and Lang Zhou. "General Molecular Dynamics Approach to Understand the Mechanical Anisotropy of Monocrystalline Silicon under the Nanoscale Effects of Point Defect." Nanomaterials 11, no. 8 (July 30, 2021): 1965. http://dx.doi.org/10.3390/nano11081965.

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Mechanical anisotropy and point defects would greatly affect the product quality while producing silicon wafers via diamond-wire cutting. For three major orientations concerned in wafer production, their mechanical performances under the nanoscale effects of a point defect were systematically investigated through molecular dynamics methods. The results indicated anisotropic mechanical performance with fracture phenomena in the uniaxial deformation process of monocrystalline silicon. Exponential reduction caused by the point defect has been demonstrated for some properties like yield strength and elastic strain energy release. Dislocation analysis suggested that the slip of dislocations appeared and created hexagonal diamond structures with stacking faults in the [100] orientation. Meanwhile, no dislocation was observed in [110] and [111] orientations. Visualization of atomic stress proved that the extreme stress regions of the simulation models exhibited different geometric and numerical characteristics due to the mechanical anisotropy. Moreover, the regional evolution of stress concentration and crystal fracture were interrelated and mutually promoted. This article contributes to the research towards the mechanical and fracture anisotropy of monocrystalline silicon.

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NITTA, S., T. KASHIMA, R. NAKAMURA, M. IWAYA, H. AMANO, and I. AKASAKI. "MASS TRANSPORT OF GaN AND REDUCTION OF THREADING DISLOCATIONS." Surface Review and Letters 07, no. 05n06 (October 2000): 561–64. http://dx.doi.org/10.1142/s0218625x00000567.

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Mass transport of patterned GaN at around 1100°C in nitrogen with an ammonia atmosphere has been discovered for the first time. The mass transport process is found to be affected by the anisotropy of surface energy of GaN. Behaviors of threading dislocations which are predominantly of the mixed type and the pure edge type are affected by the anisotropy during mass transport. Mixed type dislocations are bent keeping the geometrical relationship normal to the surfaces, while pure edge type dislocations are bent horizontally. This new-found process, the so-called "mass transport epitaxy," is one of the best methods for achieving low dislocation density GaN on the highly lattice-mismatched substrate.

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Ouyang, Fang, Jianguo Zhao, Shikun Dai, and Shangxu Wang. "Seismic wave modeling in vertically varying viscoelastic media with general anisotropy." GEOPHYSICS 86, no. 4 (June 15, 2021): T211—T227. http://dx.doi.org/10.1190/geo2020-0406.1.

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Seismic anisotropy, wave attenuation, and dispersion are critical phenomena of wave propagation in real media. Full-wavefield modeling of wave behavior in such media plays an important role in investigating dynamic features of the earth’s interior and in full-waveform inversion of anisotropic parameters and velocity dispersion. We have developed a numerical scheme to model the full-waveform response from a point source in a vertically varying viscoelastic medium of arbitrary anisotropy. The method is implemented in the frequency domain, so the complexity of anelasticity and anisotropy can be described by a complex elastic stiffness matrix and frequency-dependent moduli can also be readily incorporated. In our scheme, we solve the elastodynamic equations for general anisotropy through finite-element method in the frequency-wavenumber domain and we use the stiffness reduction method to suppress reflections from artificial boundaries along the depth direction. A nonuniform 2D Fourier transform strategy is developed to reconstruct the spatial-domain counterparts from the wavenumber-domain solutions. The time-domain responses are then obtained by taking inverse fast Fourier transform with respect to frequency. We validate the method by comparing the numerical results with the exact solutions for a homogeneous transversely isotropic model and a two-layered model. In the application example, we further proved the feasibility and generality of the scheme using an attenuative, dispersive model with velocity and attenuation anisotropy. Our scheme enjoys significant advantages in incorporating various viscoelastic/dispersive behaviors and general anisotropy, and thus provides a useful tool for numerical simulation of dynamic responses in practical application.

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Talapatra, A., and J. Mohanty. "Anisotropy Induced Switching Field Distribution in High-Density Patterned Media." SPIN 07, no. 02 (June 2017): 1750005. http://dx.doi.org/10.1142/s2010324717500059.

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We present here micromagnetic study of variation of switching field distribution (SFD) in a high-density patterned media as a function of magnetic anisotropy of the system. We consider the manifold effect of magnetic anisotropy in terms of its magnitude, tilt in anisotropy axis and random arrangements of magnetic islands with random anisotropy values. Our calculation shows that reduction in anisotropy causes linear decrease in coercivity because the anisotropy energy tries to align the spins along a preferred crystallographic direction. Tilt in anisotropy axis results in decrease in squareness of the hysteresis loop and hence facilitates switching. Finally, the experimental challenges like lithographic distribution of magnetic islands, their orientation, creation of defects, etc. demanded the distribution of anisotropy to be random along with random repetitions. We have explained that the range of anisotropy values and the number of bits with different anisotropy play a key role over SFD, whereas the position of the bits and their repetitions do not show a considerable contribution.

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30

Birn, Joachim, S. Peter Gary, and Michael Hesse. "Microscale anisotropy reduction and macroscale dynamics of the magnetotail." Journal of Geophysical Research 100, A10 (1995): 19211. http://dx.doi.org/10.1029/95ja01401.

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Junqueira, M. A. F. C., L. H. Gabrielli, and D. H. Spadoti. "Comparison of Anisotropy Reduction Strategies for Transformation Optics Designs." IEEE Photonics Journal 7, no. 1 (February 2015): 1–10. http://dx.doi.org/10.1109/jphot.2015.2396008.

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Patel, S., P. Varma, M. S. Tiwari, and N. Shukla. "Effect of ion beam on electromagnetic ion cyclotron instability in hot anisotropic plasma-particle aspect analysis." Annales Geophysicae 29, no. 8 (August 30, 2011): 1469–78. http://dx.doi.org/10.5194/angeo-29-1469-2011.

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Abstract. Using the general loss-cone distribution function electromagnetic ion cyclotron (EMIC) instability affected by up going ion beam has been studied by investigating the trajectories of charged particles. The plasma consisting of resonant and non-resonant particles has been considered. It is assumed that the resonant particles participate in energy exchange with the wave, whereas non-resonant particles support the oscillatory motion of the wave. The effect of ion beam velocity on the dispersion relation, growth rate, parallel and perpendicular resonant energy of the EMIC wave with general loss-cone distribution function in hot anisotropic plasma is described by particle aspect approach. The effect of beam anisotropy and beam density on electromagnetic ion cyclotron instabilities is investigated. Growth length is derived for EMIC waves in hot anisotropic plasma. It is found that the effect of the ion beam is to reduce the energy of transversely heated ions, whereas the thermal anisotropy of the background plasma acts as a source of free energy for the EMIC wave and enhances the growth rate. It is observed that ion beam velocity opposite to the wave propagation and its density reduces the growth rate and enhance the reduction in perpendicularly heated ions energy. The effect of ion beam anisotropy on EMIC wave is also discussed. These results are determined for auroral acceleration region. It is also found that the EMIC wave emissions occur by extracting energy of perpendicularly heated ions in the presence of an up flowing ion beam.

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A. Zainulabdeen, Ahmed, Jabbar H. Mohmmed, and Najmuldeen Y. Mahmood. "Effect of Annealing Treatment on the Anisotropy Behavior of Cold Rolled Stainless Steel 304 Sheets." Diyala Journal of Engineering Sciences 11, no. 2 (June 1, 2018): 84–89. http://dx.doi.org/10.24237/djes.2018.11212.

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Anisotropy of materials has harmful effects during deep drawing operations and reduce it will strongly enhance the productivity and quality of deep drawing yields. In this work the effect of annealing treatment on texture and anisotropy behavior of cold rolled stainless steel 304 sheets were investigated. Uniaxial tensile test samples cut at 0o, 45o and 90o to the rolling direction were prepared in order to measure the anisotropy parameters (normal anisotropy, r_n, and planar anisotropy, ∆r). Two annealing temperatures (1050, and 1150) °C were used to study their effects on anisotropy behavior. The results show that the normal anisotropy value of annealed samples at 1150°C increases by (31%) as compared to the received samples. This indicates that the annealed samples at 1150 °C have the highest formability. Also, results show significant reduction (about 88.7%) in planar anisotropy value for 1150°C annealed samples. This gave rise to an increase in deep drawing yield

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Gao, Yan, Ketian Sun, Quan Yuan, and Tiangen Shi. "Stiffness Anisotropy and Micro-Mechanism of Calcareous Sand with Different Particle Breakage Ratios Subjected to Shearing Based on DEM Simulations." Journal of Marine Science and Engineering 12, no. 5 (April 24, 2024): 702. http://dx.doi.org/10.3390/jmse12050702.

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Stress-induced anisotropy in calcareous sand can cause an uneven displacement in island reef engineering. In this study, stiffness, as a quantitative indicator, is explored to reveal the stress-induced anisotropy in calcareous sand. Based on the discrete element method, the stiffness anisotropic characteristics of calcareous sand during shearing, as well as the impact of particle breakage, are investigated by numerical simulations. Both the macro and micro responses, i.e., the maximum shear modulus, contact normal, strong and weak contact normal force, and the direction of particle breakage, are explored for calcareous sand with different particle breakage ratios. The results show that calcareous sand exhibits notable anisotropy during shearing, with the maximum shear modulus in the vertical direction (deviatoric stress direction) being significantly greater than that in the horizontal direction. Moreover, the higher the particle breakage rate, the lower the stiffness and its anisotropy. The micro-mechanism results indicate that the primary particle breakage during the shearing process occurs in the vertical direction. That is, the particle breakage weakens the strong contact force in the vertical direction, leading to a redistribution of the strong contact forces from the vertical direction to other directions. This redistribution mainly manifests in a decrease in the anisotropy of contact normal and contact vector within the sample, as well as a decrease in the proportion of strong contact forces in the overall contacts. This, in turn, reduces the shear strength and stiffness of calcareous sand, particularly in the vertical direction, and results in a decrease in the maximum shear modulus and its anisotropy. The maximum reduction can be up to 50% of the original value. These insights can provide a certain theoretical support for the uneven displacement and long-term stability of calcareous sand for islands and reefs.

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L'vov, Victor A., and Volodymyr A. Chernenko. "Magnetic Anisotropy of Ferromagnetic Martensites." Materials Science Forum 684 (May 2011): 31–47. http://dx.doi.org/10.4028/www.scientific.net/msf.684.31.

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The analytic survey of experimental and theoretical studies of the magnetic anisotropy of ferromagnetic shape memory alloys (FSMAs) is presented. The interdependence between the magnetic anisotropy of FSMAs, their lattice parameters, microstructure, and magnetostrain properties is considered. The temperature dependencies of the magnetocrystalline anisotropy energy density (MAED) and magnetically induced mechanical stress are described in the framework of magnetoelastic model based on Landau theory of phase transitions. The magnetic anisotropy of thin martensitic platelets/films and wires is considered. The effect of compensation of magnetocrystalline anisotropy by the magnetostatic one is studied. The reduction of MAED as a result of internal twinning of single crystal is discussed. The possibility of observation of reversible magnetic-fieldinduced strain in the twinned FSMAs with reduced MAED is demonstrated.

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Denisova, Elena, Lidia Chekanova, Rauf Iskhakov, Sergey Komogortsev, Ivan Nemtsev, Dmitry Velikanov, and Svetlana Mel’nikova. "Magnetic Anisotropy of Co-Nanostructures Embedded in Matrices with Different Pores Size and Morphology." Solid State Phenomena 233-234 (July 2015): 583–86. http://dx.doi.org/10.4028/www.scientific.net/ssp.233-234.583.

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Composite materials with Co (P) particles embedded into pores of silica and track etched polycarbonate membranes were fabricated by an electroless reduction. The magnetic and structural properties of the composite materials are characterized by scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometer. The macroscopic and local magnetic anisotropy of the Co (P) particles electroless deposited in the pores of the polycarbonate membrane and silica is studied. The composite materials with linear pores exhibit uniaxial magnetic anisotropy. The easy axis lies along the Co (P) rods, the shape anisotropy dominates over the intrinsic crystalline anisotropy. Information on local anisotropy field and the grain size was obtained from investigation of approach to saturation magnetization law. The local anisotropy field for all the samples depends on P content. For Co (P) rods the local anisotropy value is also determined by nominal pore sizes. It was found that the investigated Co (P) rods is nanocrystalline. The effects of different pores morphology on the FMR-spectra characteristics are studied.

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37

Kito, Shinsuke, Jiuk Jung, Tetsuo Kobayashi, and Yoshihiko Koga. "Fiber tracking of white matter integrity connecting the mediodorsal nucleus of the thalamus and the prefrontal cortex in schizophrenia: A diffusion tensor imaging study." European Psychiatry 24, no. 5 (June 2009): 269–74. http://dx.doi.org/10.1016/j.eurpsy.2008.12.012.

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AbstractThe goal of this study was to detect abnormalities in white matter integrity connecting the mediodorsal nucleus of the thalamus and the prefrontal cortex using fiber-tracking technique. Diffusion tensor imaging was acquired in 20 patients with schizophrenia and 20 normal comparison subjects. Fiber tracking was performed on the anterior thalamic peduncle, and the tractography was used to determine the cross-sectional area, mean fractional anisotropy, and standard deviation of fractional anisotropy for every step separately in the right and left hemispheres. Compared with normal subjects, patients showed a significant reduction in the cross-sectional area of the left anterior thalamic peduncle. There were no significant differences for the mean fractional anisotropy bilaterally between the two groups, but significant differences for the standard deviation of fractional anisotropy in both hemispheres. Reduction in the cross-sectional area of the left anterior thalamic peduncle suggests the presence of the failure of left-hemisphere lateralization. In schizophrenic patients a significant increase of the standard deviation of fractional anisotropy raise the possibility that the inhomogeneity of white matter integrity, which is densely or sparsely distributed by site. These findings might provide further evidence for disruption of white matter integrity between the thalamus and the prefrontal cortex in schizophrenia.

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38

Di, Yong Jiang, Peng Jun Cao, Bi Jia, and Jian Jun Jiang. "Micromagnetic Simulation on the Microwave Magnetic Properties of Glass-Coated Amorphous Alloy Microwires." Advanced Materials Research 668 (March 2013): 733–36. http://dx.doi.org/10.4028/www.scientific.net/amr.668.733.

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The magnetic structure of the glass-coated magnetic alloy microwires were modeled based on the main magnetic domain structure and meshed by finite element method. The magnetic spectrum of the magnetic alloy microwires was calculated based on the micromagnetic theory. The simulation results of the magnetic spectrum of glass-coated magnetic alloy microwires showed that the magnetic anisotropy field increase as the magneto-crystalline anisotropy constants increase. The microwave resonance frequency increased accompanied by the reduction of the permeability and the increase of the magnetic anisotropy field of the glass-coated magnetic alloy microwires.

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Liang, Yu, Jun Ma, Baogang Zhou, and Wei Li. "Selective Anisotropy of Mechanical Properties in Inconel718 Alloy." Materials 14, no. 14 (July 11, 2021): 3869. http://dx.doi.org/10.3390/ma14143869.

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Mechanical anisotropy behaviors are investigated in slightly rolled Inconel718 alloy with string-like δ phase and carbides produced during various solid-solution and aging treatments. A weak anisotropy in the strengths and rupture properties at 650 °C is visible, whereas ductility, i.e., reduction in area (RA) and impact toughness (CVN), presents a sound anisotropy behavior. MC carbides promote the operation of slip systems and thus are conducive to weakening the strength anisotropy. The RA anisotropy mainly stems from high-density δ phase particles that provide more crack nucleation sites and stimulate rapid propagation because of the shorter bridge distance between micro-cracks at the rolling direction. In contrast, CVN anisotropy arises from both δ phase and carbides at a lower solid-solution temperature of 940 °C but only depends on carbides at 980 °C where the δ phase fully dissolves. Apart from dislocation motions operated at room temperature, the activated grain boundary processes are responsible for the weak anisotropy of rupture properties at the elevated temperature. This work provides a guideline for technological applications in the hot working processes for Inconel718 alloys.

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Dzenis, Yu A., and S. P. Joshi. "Damage Induced Anisotropy in Laminates." Advanced Composites Letters 2, no. 3 (May 1993): 096369359300200. http://dx.doi.org/10.1177/096369359300200303.

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A damage evolution model developed by the authors is utilized to study the effect of damage induced anisotropy on constitutive behavior and failure strength of laminates. It is shown that extension-shear coupling coefficients of the in-plane stiffness matrix radically change due to unequal damage accumulation in plies with opposite orientation under shear loading. This, in general, causes significant reduction in laminate shear strength. The angle-ply orientation and presence of zero degree plies in a laminate have a notable effect on damaged induced anisotropy.

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41

Vargas, J. M., E. Lima, R. D. Zysler, J. G. S. Duque, E. De Biasi, and M. Knobel. "Effective anisotropy field variation of magnetite nanoparticles with size reduction." European Physical Journal B 64, no. 2 (July 2008): 211–18. http://dx.doi.org/10.1140/epjb/e2008-00294-6.

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42

Juntunen, J. S., and T. D. Tsiboukis. "Reduction of numerical dispersion in FDTD method through artificial anisotropy." IEEE Transactions on Microwave Theory and Techniques 48, no. 4 (April 2000): 582–88. http://dx.doi.org/10.1109/22.842030.

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43

Arote, Ashish, Junji Shinjo, D. Graham McCartney, and Roger C. Reed. "Grid anisotropy reduction method for cellular automata based solidification models." Computational Materials Science 217 (January 2023): 111880. http://dx.doi.org/10.1016/j.commatsci.2022.111880.

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44

Kim, Tae Hyeong, Jaimyun Jung, and Jae Wung Bae. "Suppressed Plastic Anisotropy via Sigma-Phase Precipitation in CoCrFeMnNi High-Entropy Alloys." Materials 17, no. 6 (March 8, 2024): 1265. http://dx.doi.org/10.3390/ma17061265.

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The effect of sigma-phase precipitation on plastic anisotropy of the equiatomic CoCrFeMnNi high-entropy alloy was investigated. Annealing at 700 °C after cold-rolling leads to the formation of the Cr-rich σ phase with a fraction of 2.7%. It is experimentally found that the planar anisotropy (∆r = −0.16) of the CoCrFeMnNi alloy annealed at 700 °C is two times lower than that of the alloy annealed at 800 °C (∆r = −0.35). This observation was further supported by measuring the earing profile of cup specimens after the deep drawing process. The plastic strain ratio, normal anisotropy, and planar anisotropy were also predicted using the visco-plastic self-consistent model. The results indirectly indicated that the reduction of plastic anisotropy in alloy annealed at 700 °C can be attributed to the formation of the σ phase.

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45

Zubov, V. E., A. D. Kudakov, N. L. Levsнin, M. Yu Gusev, and N. S. Neustroev. "Domain Structure Reversible Reconstruction and Changing of Domains Width in Ferrite-Garnet Films Caused by Water Molecules Adsorption." Solid State Phenomena 190 (June 2012): 538–41. http://dx.doi.org/10.4028/www.scientific.net/ssp.190.538.

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Due to water molecules adsorption the reversible change of domains width and domain structure reconstruction in bismuth-doped ferrite-garnet thin films with perpendicular magnetic anisotropy was observed. The change of domains width was 15% in saturated water vapor at room temperature. The decrease of domains width is explained by the reduction of effective perpendicular magnetic anisotropy constant due to water molecules adsorption.

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Tsvankin, Ilya. "Anisotropic parameters and P‐wave velocity for orthorhombic media." GEOPHYSICS 62, no. 4 (July 1997): 1292–309. http://dx.doi.org/10.1190/1.1444231.

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Although orthorhombic (or orthotropic) symmetry is believed to be common for fractured reservoirs, the difficulties in dealing with nine independent elastic constants have precluded this model from being used in seismology. A notation introduced in this work is designed to help make seismic inversion and processing for orthorhombic media more practical by simplifying the description of a wide range of seismic signatures. Taking advantage of the fact that the Christoffel equation has the same form in the symmetry planes of orthorhombic and transversely isotropic (TI) media, we can replace the stiffness coefficients by two vertical (P and S) velocities and seven dimensionless parameters that represent an extension of Thomsen's anisotropy coefficients to orthorhombic models. By design, this notation provides a uniform description of anisotropic media with both orthorhombic and TI symmetry. The dimensionless anisotropic parameters introduced here preserve all attractive features of Thomsen notation in treating wave propagation and performing 2-D processing in the symmetry planes of orthorhombic media. The new notation has proved useful in describing seismic signatures outside the symmetry planes as well, especially for P‐waves. Linearization of P‐wave phase velocity in the anisotropic coefficients leads to a concise weak‐anisotropy approximation that provides good accuracy even for models with pronounced polar and azimuthal velocity variations. This approximation can be used efficiently to build analytic solutions for various seismic signatures. One of the most important advantages of the new notation is the reduction in the number of parameters responsible for P‐wave velocities and traveltimes. All kinematic signatures of P‐waves in orthorhombic media depend on just the vertical velocity [Formula: see text] and five anisotropic parameters, with [Formula: see text] serving as a scaling coefficient in homogeneous media. This conclusion, which holds even for orthorhombic models with strong velocity anisotropy, provides an analytic basis for application of P‐wave traveltime inversion and data processing algorithms in orthorhombic media.

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Higuchi, Ryo, Takashi Sako, Toshihiro Fujii, Kazumasa Kawata, and Eiji Kido. "Estimation and reduction of the biases by the galactic magnetic field on the UHECR correlation studies." EPJ Web of Conferences 283 (2023): 03011. http://dx.doi.org/10.1051/epjconf/202328303011.

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The correlation studies between ultrahigh-energy cosmic ray (UHECR) anisotropy and source candidates are keys to understand the origin of UHECRs. Especially, studies with consideration of source models, magnetic fields, and mass compositions are necessary. We estimated the biases caused by the coherent deflection due to the galactic magnetic field (GMF) in the previous maximum-likelihood analysis for searching the UHECR sources (Aab et al. 2018, Abbasi et al. 2018). In our work with simulated mock datasets, we find that the anisotropic fraction fani is estimated systematically lower than the true value when we ignore the effect caused by the GMF. We also develop the maximum-likelihood method which includes the GMF model and confirm that the estimated parameters would be improved. We apply the method to the observational datasets obtained from the Telescope Array and Auger experiments.

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Kulitskiy, Vladislav, Sergey Malopheyev, and Rustam Kaibyshev. "Effect of Extensive Isothermal Rolling on Microstructure and Mechanical Properties of an Al-Mg-Sc Alloy." Materials Science Forum 794-796 (June 2014): 1187–92. http://dx.doi.org/10.4028/www.scientific.net/msf.794-796.1187.

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The evolution of microstructure and mechanical properties of an Al-5.4Mg-0.4Mn-0.2Sc-0.09Zr alloy subjected to rolling at 300oC was studied. It was shown that the rolling of the alloy leads to strong anisotropy in mechanical properties. The formation of the lamellar structure occurs at a total reduction of 60% due to alignment of initial boundaries along rolling direction (RD), and appearance of geometrically necessary boundaries (GNB) aligned with {111} planes. This process is accompanied by a strong increase in the lattice dislocation density by a factor of 50. Further rolling induces the formation of subgrains within lamellar structure that diminishes the anisotropy. The GNBs have low-angle misorientations, initially. After a reduction of 80%, minor part of GNBs acquires high-angle misorientation. The formation of well-defined subgrains within lamellas leads to a decrease in the lattice dislocation density by a factor of about 10; the yield stress (YS) decrease is -25% along the RD. At the same time the YS in the transverse direction tends to increase with increasing reduction from 60 to 80%. The effect of the deformation structure on the mechanical properties and their anisotropy is discussed.

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Lin, Che-Yu, Bayode E. Owolabi, and Chao-An Lin. "Polymer-turbulence interactions in a complex flow and implications for the drag reduction phenomenon." Physics of Fluids 34, no. 4 (April 2022): 043106. http://dx.doi.org/10.1063/5.0086686.

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We present direct numerical simulation data for turbulent duct flow of a finite-extensibility non-linear elastic dumbbell model with the Peterlin approximation (FENE-P) fluid in the high drag reduction regime. While the secondary flow pattern is qualitatively similar to that in a Newtonian fluid, its magnitude is significantly reduced, resulting in a less uniformly distributed velocity profile and hence smaller gradients at the wall. The Reynolds stress tensor in the polymer-laden flow was found to be increasingly anisotropic with most of the turbulent kinetic energy retained in the streamwise component, [Formula: see text]. We introduce a novel approach for investigating polymer stretching using the anisotropy invariant map of the polymer stress tensor and observe the persistence of both uniaxial and biaxial extension. Analysis of the transport equation for the mean kinetic energy indicates that polymer stretching and relaxation is a highly dissipative process; hence, the introduction of an additional channel for dissipation in a flow is key to drag reduction.

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Zhu, Yaping, and Ilya Tsvankin. "Plane-wave attenuation anisotropy in orthorhombic media." GEOPHYSICS 72, no. 1 (January 2007): D9—D19. http://dx.doi.org/10.1190/1.2387137.

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Orthorhombic models are often used in the interpretation of azimuthally varying seismic signatures recorded over fractured reservoirs. Here, we develop an analytic framework for describing the attenuation coefficients in orthorhombic media with orthorhombic attenuation (i.e., the symmetry of both the real and imaginary parts of the stiffness tensor is identical) under the assumption of homogeneous wave propagation. The analogous form of the Christoffel equation in the symmetry planes of orthorhombic and VTI (transversely isotropic with a vertical symmetry axis) media helps to obtain the symmetry-plane attenuation coefficients by adapting the existing VTI equations. To take full advantage of this equivalence with transverse isotropy, we introduce a parameter set similar to the VTI attenuation-anisotropy parameters [Formula: see text], [Formula: see text], and [Formula: see text]. This notation, based on the same principle as Tsvankin’s velocity-anisotropy parameters for orthorhombic media, leads to concise linearized equations for thesymmetry-plane attenuation coefficients of all three modes (P, [Formula: see text], and [Formula: see text]).The attenuation-anisotropy parameters also allow us to simplify the P-wave attenuation coefficient [Formula: see text] outside the symmetry planes under the assumptions of small attenuation and weak velocity and attenuation anisotropy. The approximate coefficient [Formula: see text] has the same form as the linearized P-wave phase-velocity function, with the velocity parameters [Formula: see text] and [Formula: see text] replaced by the attenuation parameters [Formula: see text] and [Formula: see text]. The exact attenuation coefficient, however, also depends on the velocity-anisotropy parameters, while the body-wave velocities are almost unperturbed by the presence of attenuation. The reduction in the number of parameters responsible for the P-wave attenuation and the simple approximation for the coefficient [Formula: see text] provide a basis for inverting P-wave attenuation measurements from orthorhombic media. The attenuation processing must be preceded by anisotropic velocity analysis that can be performed (in the absence of pronounced velocity dispersion) using existing algorithms for nonattenuative media.

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Journal articles on the topic 'Anisotropy reduction'

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