Direction Of Anisotropy Research Articles

Relationship between UCS and Anisotropic Angle: A Case Study for Slate of Himalaya Region

The strength of rocks exhibits anisotropy, because of its mode of formation and its developing through different pressure and temperature environment. A rock can display anisotropy due to inhomogeneity, where sedimentary varying with the degree of the anisotropic plane. This strength anisotropy" refers to the change in intact rock strength under uniaxial loading conditions based on the orientation of anisotropy, the strength and deformation behavior of rocks under load is critical for underground excavations, mining, and civil engineering projects, as it directly impacts the stability of such structures. This study examines the strength index, which is influenced by the anisotropic plane at different loading angles. The rock material, characterized by layers developed by platy minerals with sometime varying grain sizes, shows that an increase in foliation degree to loading angle directly impacts its strength. In slate, the strength index is influenced by the anisotropic plane and loading direction, which are also controlled by characters of mineral grains. This study seeks to enhance the existing understanding of this behavior by analyzing uniaxial compressive strength (UCS) performed on anisotropic low grade metamorphic rock.

Multi-scale fracture characterization method for transitional shale reservoir based on post-stack multi-attribute ant-tracking fusion and pre-stack wide-azimuth gathers AVAZ analysis

Transitional shale gas represents a significant domain for exploration in the oil and gas sector. The distribution area is extensive, and the resource potential is significant, representing approximately 25% of China's total shale gas resources. Approaches for predicting reservoir fractures using seismic attributes has been well-established. Seismic attributes are frequently constrained by elements including the frequency and resolution of seismic data. The characteristics of transitional shale reservoirs, including complex lithological combinations, frequent changes in lithology, low resolution and variable frequency of seismic data, as well as the presence of strong reflection shielding in coal seams, significantly influence fracture prediction. The use of a single seismic attribute technique presents challenges in delivering a thorough and precise prediction of fractures within transitional reservoirs. This study extracts discontinuity information of large fractures, fine fractures, and fractures obscured by strong reflections from coal seams using variance attributes, amplitude contrast attributes, and the amplitude of diffracted waves, respectively. The discontinuity features obtained from the three methods are monitored through an ant-tracking technique and integrated. Fractures in the work area are methodically described. The near-offset Rüger formula method is utilized to analyze the pre-stack wide-azimuth gathers. Anisotropic gradients and anisotropic directions have been derived. The results of the fracture prediction are analyzed and validated. A novel and reliable methodology, designed specifically for the challenges of transitional shale reservoirs, has been developed for combined pre-stack and post-stack seismic multi-scale fracture prediction. The robust reflection shielding effect of the coal seam has been effectively eliminated. The characterization of fractures in transitional shale reservoirs has been enhanced.

Thermal expansion and ionic conductivity of K5Pb0,5Zr1,5 (MoO4)6

The present study is aimed at the directed synthesis of a new ternary molybdate K5Pb0.5Zr1.5(MoO4)6 isostructural to K5Pb0.5Hf1.5(MoO4)6 by solid-phase reaction within the temperature range of 350–550 °С (for 100 h). The compound crystallizes in the rhombohedral system with the space group R3̅ and unit cell parameters of a = 10.6604(2) Å, c = 37.9769(9) Å, and V = 3737.6(2) Å3. The structure was refined using the Rietveld method. The atomic positions were refined in the isotropic approximation, with soft constraints on Mo–O distances and O–Mo–O bond angles. The crystal structure constitutes a 3D scaffold comprising PbO6 and ZrO6 octahedrons and MoO4 tetrahedrons sharing oxygen vertices. The thermal expansion of K5Pb0.5Zr1.5(MoO4)6 was studied via high-temperature X-ray powder diffraction. The calculated thermal expansion coefficients along both crystallographic axes remain positive over the entire temperature range. In this case, the value of αa remains constant, while that of αc increases with rising temperature. The obtained ternary molybdate belongs to materials with high thermal expansion (αV = 60×10-6 °С-1). The significant anisotropy in the crystallographic direction c can be attributed to the soft K–O and Pb-O bonds. The electrical conductivity of K5Pb0.5Zr1.5(MoO4)6 was studied via impedance spectroscopy within the temperature range of 30–500 °С; at 500 °С, the conductivity amounted to 0.7×10-4 S/cm, with Ea = 0.59 eV.

Evaluation of three modelling frameworks of thermal infrared radiative transfer for directional anisotropies of temperatures

Evaluation of three modelling frameworks of thermal infrared radiative transfer for directional anisotropies of temperatures

Improvement of directional anisotropy and its impact on surface and mechanical properties of a rib-on-plate structure fabricated through friction stir processing of additively manufactured friction stir surfaced structure

Improvement of directional anisotropy and its impact on surface and mechanical properties of a rib-on-plate structure fabricated through friction stir processing of additively manufactured friction stir surfaced structure

Strain Control of Third Harmonic Generation in Nb2SiTe4 Driven by Tuneable Anisotropic Characteristics

AbstractStrain engineering constitutes one of the main control knobs for material properties. The material's crystal and band structure can be strongly modified by mechanical strain, thus tailoring the electronic and photonic properties toward specific applications. However, the strain control of the higher‐order nonlinear optical (NLO) processes in crystals characterized by in‐plane anisotropy remains mostly unexplored. It is demonstrated that 2D ternary Nb2SiTe4 crystals provide an excellent platform for tuning NLO properties with uniaxial strain due to the inherently anisotropic band structure around the fundamental bandgap in the near‐infrared region. Resonant conditions between the interband excitations and third harmonic signals are realized, a record‐high third‐order susceptibility of 2.43 × 10−18m2/V2 is observed, exceeding by over an order of magnitude the values reported for commonly used NLO crystals. The measurements of the third harmonic intensity as a function of the linear polarization revealed that the anisotropic characteristics of Nb2SiTe4 can be tuned into qualitatively different regimes by the application of a uniaxial strain along the principal crystallographic axes. Notably, with increasing strain, the characteristic anisotropic direction can be reoriented. The findings provide unique perspectives for applying the modulation of the broadband NLO properties enabled by anisotropic materials in optoelectronics and all‐optical devices.

Impact of Cell Design Parameters on Mechanical Properties of 3D-Printed Cores for Carbon Epoxy Sandwich Composites.

The introduction of 3D printing technology has broadened manufacturing possibilities, allowing the production of complex cellular geometries, including auxetic and curved plane structures, beyond the standard honeycomb patterns in sandwich composite materials. In this study, the effects of cell design parameters, such as cell geometry (honeycomb and auxetic) and cell size (cell thickness and width), are examined on acrylonitrile butadiene styrene (ABS) core materials produced using fusion deposition modeling (FDM). They are produced as a result of the epoxy bonding of carbon epoxy prepreg composite materials to the surfaces of core materials. Increasing the wall thickness from 0.6 mm to 1 mm doubled the elastic modulus of the re-entrant structures (5 GPa to 10 GPa) and improved compressive strength by 50-60% for both geometries. In contrast, increasing cell size from 6 mm to 10 mm significantly reduced compressive strength by 80% (from 2.5-2.8 MPa to 0.5-0.6 MPa) and elastic modulus by 70-78% (from 9-10 GPa to 2-3 GPa). Flexural testing showed that the re-entrant cores, with a maximum load capacity of 148 N, exhibited more uniform deformation, while the honeycomb cores achieved a higher load capacity of 273 N but were prone to localized failures. These findings emphasize the directional anisotropy and specific advantages of auxetic and honeycomb designs, offering valuable insights for lightweight, high-strength structural applications.

Quasi-One-Dimensional Spin Dynamics in a Molecular Spin Liquid System.

The molecular triangular lattice system, β^{'}-EtMe_{3}Sb[Pd(dmit)_{2}]_{2}, is considered as a candidate material for the quantum spin liquid state, although ongoing debates arise from recent controversial results. Here, the results of electron spin resonance and muon-spin relaxation measurements on β^{'}-EtMe_{3}Sb[Pd(dmit)_{2}]_{2} are presented. Both results indicate characteristic behaviors related to quasi-one-dimensional spin dynamics, whereas the direction of anisotropy found in electron spin resonance is in contradiction with previous theories. We succeed in interpreting the experiments by combining density-functional theory calculations and analysis of the effective model taking into account the multiorbital nature of the system. While the quantum-spin-liquid-like origin of β^{'}-EtMe_{3}Sb[Pd(dmit)_{2}]_{2} was initially attributed to the magnetic frustration of the triangular lattice, it appears that the primary origin is a 1D spin liquid resulting from the dimensional reduction effect.

Serial Dependence in Smooth Pursuit Eye Movements of Preadolescent Children and Adults.

Serial dependence refers to the attraction of current perceptual responses toward previously seen stimuli. Despite extensive research on serial dependence, fundamental questions, such as how serial dependence changes with development, whether it affects the perception of sensory input, and what qualifies as serial dependence, remain unresolved. The current study aims to address these questions. We tested 81 children (8-9 years) and 77 adults (18-30 years) with an ocular tracking task in which participants used their eyes to track a target moving in a specific direction on each trial. This task examined both the open-loop (pursuit initiation) and closed-loop (steady-state tracking) smooth pursuit eye movements. We found an attractive bias in pursuit direction toward previously seen target motion direction during pursuit initiation but not sustained pursuit in both children and adults. Such a bias displayed both feature- and temporal-tuning characteristics of serial dependence, showed oblique-cardinal directional anisotropy, and was more pronounced in children than adults. The greater effect of serial dependence around oblique than cardinal directions and its increased magnitude in children compared to adults can be explained by the larger variability in pursuit direction around oblique directions and in children, as predicted by the Bayesian framework. Serial dependence in smooth pursuit occurs early during pursuit initiation when the response is driven by the perception of sensory input. Age-related changes in serial dependence reflect the fine-tuning of general brain functions, enhancing precision in tracking a moving target and thus reducing serial dependence effects.

Geodesic Distance Integration in Analytical Frameworks for Aquifer Hydraulic Modeling

AbstractTraditional analytical models in groundwater studies often simplify the complexities arising from spatial variations in aquifer geometry and anisotropy, limiting their ability to capture the full theoretical nuances of groundwater flow. In this study, we present a novel methodology that integrates geodesic distances within the intrinsic geometry of confined, constant‐thickness aquifers, while also accounting for directional anisotropy in hydraulic properties. This approach provides a rigorous mathematical framework for accurately capturing the true distances along the aquifer geometry between pumping and observation wells, in contrast to traditional Euclidean distances. Our methodology is compatible with various analytical solutions, including the Theis (1935, https://doi.org/10.1111/jawr.1965.1.3.9) and Papadopulos and Cooper (1967, https://doi.org/10.1029/wr003i001p00241) solutions, extending their theoretical applicability to more complex aquifer geometries and anisotropic conditions. Numerical simulations of synthetic examples illustrate the theoretical consistency of the proposed approach, aligning drawdown patterns within this advanced framework. While primarily focused on enhancing existing analytical models, this methodology sets the stage for future theoretical advances in groundwater modeling, offering a conceptual expansion of analytical solutions to better address geometric and anisotropic complexities.

QCD phase transition with nonextensive NJL model in the strong magnetic field

In this work we make use of the Nambu–Jona-Lasinio model to investigate thermodynamic properties of magnetized three-flavor quark matter. The nonequilibrium Tsallis distribution is characterized by a dimensionless nonextensive parameter q. We find that the system always undergoes a crossover transition for all given q values and the pseudocritical temperature decreases with the increasing nonextensive parameter. We show the variation of the pressure and its anisotropy in parallel and perpendicular directions. However, the diamagnetic nature appears within a certain temperature range at zero chemical potential. Moreover, strong magnetic fields can affect the property of a nonextensive system by changing the magnetization significantly. At high temperatures, the paramagnetic nature always occurs no matter how strong the magnetic field is. Finally, we study the effects of nonextensive parameter q on the trace anomaly and the speed of sound of the system. Published by the American Physical Society 2024

Azimuthal seismic anisotropy of the Iran plateau: Insights from ambient noise analysis

The continental lithosphere of the Iran plateau is complicated by many tectonic processes that affected both the Arabian and Eurasian plates before and after their convergence. To investigate the deformation mechanisms of the crust and mantle lithosphere, we directly invert Rayleigh wave phase velocity dispersion data (5–60 s) for a 3-D shear wave velocity and depth-dependent azimuthal anisotropy model using ambient noise tomography from the surface down to 100 km with data recorded in 84 seismic stations. The shear wave velocity maps reveal a reasonable match with geological domains and agree with those previously published. The projections of the fast axes of Rayleigh wave azimuthal anisotropy in the subcrustal lithosphere allowed us to divide the Iran plateau into two main regions: the Zagros Mountains and the rest of the country. Furthermore, the anisotropy pattern illustrates a prominent contrast between the NW and SE Zagros Mountains. In both the crust and subcrustal lithosphere, the NW Zagros shows relatively weak but coherent azimuthal anisotropy in the NE-SW direction (i.e., orogen-perpendicular orientation). We ascribe the orogen-perpendicular fast axis in NW Zagros to stress-induced anisotropy. However, in the SE Zagros, the north-northwest orientations of the fast axes are attributed to the N-S trending basement structures, which are inherited from the Pan-African construction phase. The azimuthal anisotropy pattern displays an overall NW-SE trend dominant over the rest of the country. This NW-SE direction can be explained by an NW-SE extension due to transpressional deformation beneath Central Iran resulting from the oblique indentation of the Arabian plate into Eurasia. Nevertheless, strike-parallel anisotropy directions along the western and central Alborz Mountains throughout the entire lithosphere may be related to pure shear deformation. The persistence of azimuthal anisotropy patterns in the crust and subcrustal lithosphere implies that the whole lithosphere deforms coherently in the NW Zagros, west Iran, the Alborz Mountains, and across the Lut block. However, strong contrasts between the crustal and subcrustal pattern of anisotropy observed in the SE Zagros as well as in north Central Iran suggest that in these regions, the crust and the underlying mantle lithosphere do not deform coherently. A strong correlation between the Rayleigh wave anisotropy directions at subcrustal depths and the anisotropy patterns estimated from the shear-wave core phases suggests that in many places over the plateau, the SKS directions may have been dominated by the deformation of the lithosphere.

On the accuracy of numerical methods for the discretization of anisotropic elliptic problems

In this paper the loss of precision of numerical methods discretizing anisotropic elliptic problems is analyzed. This feature is prominently observed when the coordinates and the mesh are unrelated to the anisotropy direction. This issue is carefully analyzed and related to the asymptotic instability of the discretizations. The investigations carried out within this paper demonstrate that, high order methods commonly implemented to cope with this difficulty, though bringing evident gains, remain for far from optimal and limited to moderate anisotropy strengths. A second issue, related to the reconstruction of the solution discrete parallel gradients, is also addressed. In particular, it is demonstrated that an accurate approximation can hardly be computed from a precise numerical approximation of the solution. A new method is proposed, consisting in introducing an auxiliary variable providing discrete approximations of the parallel gradient with a precision unrelated to the anisotropy strength.

Symmetry in Hyper Suprime-Cam Galaxy Spin Directions

Abstract We perform a Bayesian analysis of anisotropy in binary galaxy spin directions in the Hyper-Suprime Cam Data Release 3 catalog, in response to a recent claim that it exhibits a dipole. We find no significant evidence for anisotropy, or for a direction-independent spin probability that differs from 0.5. These results are unchanged allowing for a quadrupole or simply searching for a fixed anisotropy between any two hemispheres, and the Bayes factor indicates decisive evidence for the isotropic model. Our principled method contrasts with the statistic employed by Shamir, which lacks a strong theoretical foundation. Our code is available at ✎.

A study of crustal deformation beneath the Qinling Orogenic belt, Central China based on receiver function data

A joint shear wave splitting technique based on receiver function data is employed to invert the crustal anisotropy, Moho depth, and Vp/Vs ratio in the Qinling Orogenic belt (QOB). Our findings reveal a relatively low Vp/Vs ratio (∼1.74) and a thin crust in east QOB. This suggests that potential crustal flow from central Tibet may not significantly influence the crustal deformation in east QOB. Our results demonstrate high Vp/Vs ratios (∼1.75–1.88), thick crust (∼44–56 km), and significant crustal anisotropy with a delay time of 0.22–0.86 s in south QOB, Dabashan, and west QOB regions. The fast directions of crustal anisotropy in the south QOB and Dabashan areas are NW-SE, which reflect the orientation of crustal fabrics associated with the collision between the North China Block and the South China Block. However, weak or negligible splitting times are observed beneath the Shennongjia-Huangling (SNHL), Hannan-Micang (HNMC) domes, and Jianghan Basin. The presence of weak crustal anisotropy is likely related to the stable basements beneath two domes, while the negligible splitting time beneath the Jianghan Basin might be attributed to the nearly vertical α-axis of olivines or mica associated with a subvertical mantle flow caused by slab break-off of the subducted Yangtze Block. The underlying magmas have gathered in the lower crust and formed the mafic lower crust, which cause an increase in the crust Vp/Vs ratio and crustal extension.

Viscous tweezers: Controlling particles with viscosity

Control of particle motion is generally achieved by applying an external field that acts directly on each particle. Here, we propose a global way to manipulate the motion of a particle by dynamically changing the properties of the fluid in which it is immersed. We exemplify this principle by considering a small particle sinking in an anisotropic fluid whose viscosity depends on the shear axis. In the Stokes regime, the motion of an immersed object is fully determined by the viscosity of the fluid through the mobility matrix, which we explicitly compute for a pushpin-shaped particle. Rather than falling upright under the force of gravity, as in an isotropic fluid, the pushpin tilts to the side, sedimenting at an angle determined by the viscosity anisotropy axis. By changing this axis, we demonstrate control over the pushpin orientation as it sinks, even in the presence of noise, using a closed feedback loop. This strategy to control particle motion, that we dub viscous tweezers, could be experimentally realized in systems ranging from polyatomic fluids under external fields to chiral active fluids of spinning particles by suitably changing their direction of global alignment or anisotropy. Published by the American Physical Society 2024

Involvement of KATANIN1, a microtubule-severing enzyme, in hypergravity-induced modification of growth anisotropy in Arabidopsis hypocotyls

The mechanism by which gravity affects the growth anisotropy of plant organs is an important issue for the cultivation of plants under microgravity conditions in space. This study aimed to examine the roles of KATANIN1 (KTN1), a microtubule-severing enzyme, in the modification of the direction of cortical microtubules (CMTs) and growth anisotropy in Arabidopsis hypocotyls induced by gravity using hypergravity conditions that can be created on Earth. The KTN1 mutants (ktn1P393S, ktn1R465Q, and ktn1S342F) exhibited shorter and thicker hypocotyls than the wild type (ecotype Columbia-0). Hypergravity at 300 g modified growth anisotropy in wild-type hypocotyls; hypergravity inhibited elongation but stimulated lateral growth. In contrast, hypergravity-induced modification of growth anisotropy was suppressed in hypocotyls of the three mutants. The wild type had an abundance of CMTs in transverse orientation (between 0° and 30°) under 1 g conditions and a tendency toward increased CMTs in longitudinal orientation under hypergravity conditions (between 60° and 90°). However, hypergravity-induced reorientation was not observed in hypocotyls of ktn1 mutants. The transcript level of the KTN1 gene in wild-type hypocotyls increased within 1 h of onset of hypergravity treatment and promptly decreased to the same level as the 1 g control. These findings suggest that the reorientation of CMTs is mediated by KTN1, which is regulated by transient expression upregulation, which is responsible for the modification of growth anisotropy induced by hypergravity in Arabidopsis hypocotyls.

Mechanical properties of TPDH-graphene: atomistic aspect

Abstract TPDH-graphene is a new type of two-dimensional carbon material predicted by first-principles calculations to have tetragonal (T), pentagonal (P), decagonal (D) and hexagonal (H) carbon ring structures. First-principles calculations show that this special structure gives it excellent mechanical properties and promising applications in nanoelectronics. In this paper, a comprehensive test of its mechanical properties was carried out using the classical molecular dynamics (MD), mainly exploring the effects of factors such as tensile direction and temperature on its mechanical properties, and exploring the effects of introducing rectangular and circular defects on its mechanical properties. The results show that: TPDH-graphene exhibits significant anisotropy in zigzag and armchair directions, and the material exhibits some tensile toughness in armchair direction; the mechanical properties of the material are weakened at higher temperatures; the adding of defects leads to the reduction of the mechanical properties of the material in different directions to different degrees, and the The tensile toughness in the armchair direction is weakened by the addition of defects.

Constitutive modelling and wave propagation through a class of anisotropic elastic metamaterials with local rotation

Elastic metamaterials are typically periodic materials possessing unit cells endowed with engineered architecture much smaller than the typical phenomenological length scale. The development of continuum models capable of accurately representing the effects of this aforementioned architecture is extremely challenging, and hence a sparsely developed area. This paper develops a novel 2-D continuum model capable of capturing the dynamic behaviour of a class of anisotropic elastic metamaterials with local rotational elements in the long wavelength limit. A constitutive relation incorporating these local rotational effects is proposed, and ratified using a representative discrete model using linear Hookean springs and identical rigid disks. The new continuum model is used to generate a dispersion relation for harmonic plane waves propagating in an arbitrary direction, which is subsequently compared to the dispersion behaviour of the original discrete model. The general behaviour of this continuum when subjected to 2-D planar harmonic wave propagation in the anisotropic medium is then analysed, with specific attention given to the effect of material anisotropy and wave propagation direction. This work is the first of its kind to create a new continuum model of a class of anisotropic elastic metamaterials with local rotational effects.

Analysis of Magnetization Dynamics in NiFe Thin Films with Growth-Induced Magnetic Anisotropies

We have used angled magnetron sputter deposition with and without sample rotation to control the magnetic anisotropy in 20 nm NiFe films. Ferromagnetic resonance spectroscopy, with data analysis using a Bayesian approach, is used to extract material parameters relating to the magnetic anisotropy. When the sample is rotated during growth, only shape anisotropy is present, but when the sample is held fixed, a strong uniaxial anisotropy emerges with in-plane easy axis along the azimuthal direction of the incident atom flux. When the film is deposited in two steps, with an in-plane rotation of 90 degrees between steps, the two orthogonal induced in-plane easy-axes effectively cancel. The analysis approach enables precise and accurate determination of material parameters from ferromagnetic resonance measurements; this demonstrates the ability to precisely control both the direction and strength of uniaxial magnetic anisotropy, which is important in magnetic thin-film device applications.