Anisotropic Patterns Research Articles

Analysis and Accuracy Improvement of UWB-TDoA-Based Indoor Positioning System.

Positioning systems are used in a wide range of applications which require determining the position of an object in space, such as locating and tracking assets, people and goods; assisting navigation systems; and mapping. Indoor Positioning Systems (IPSs) are used where satellite and other outdoor positioning technologies lack precision or fail. Ultra-WideBand (UWB) technology is especially suitable for an IPS, as it operates under high data transfer rates over short distances and at low power densities, although signals tend to be disrupted by various objects. This paper presents a comprehensive study of the precision, failure, and accuracy of 2D IPSs based on UWB technology and a pseudo-range multilateration algorithm using Time Difference of Arrival (TDoA) signals. As a case study, the positioning of a 4×4m2 area, four anchors (transceivers), and one tag (receiver) are considered using bitcraze's Loco Positioning System. A Cramér-Rao Lower Bound analysis identifies the convex hull of the anchors as the region with highest precision, taking into account the anisotropic radiation pattern of the anchors' antennas as opposed to ideal signal distributions, while bifurcation envelopes containing the anchors are defined to bound the regions in which the IPS is predicted to fail. This allows the formulation of a so-called flyable area, defined as the intersection between the convex hull and the region outside the bifurcation envelopes. Finally, the static bias is measured after applying a built-in Extended Kalman Filter (EKF) and mapped using a Radial Basis Function Network (RBFN). A debiasing filter is then developed to improve the accuracy. Findings and developments are experimentally validated, with the IPS observed to fail near the anchors, precision around ±3cm, and accuracy improved by about 15cm for static and 5cm for dynamic measurements, on average.

High‐Resolution Lithospheric Structure of the Zagros Collision Zone and Iranian Plateau

AbstractFrom a joint analysis of fundamental mode Rayleigh wave group velocities and P‐wave receiver functions, we derive a new, high‐resolution 3D shear‐wave velocity (Vs) model for the crust and uppermost mantle of the Iranian Plateau. The thickest crust (>55 km) is located beneath the Sanandaj‐Sirjan Zone and the deforming belts of Alborz‐Binalud‐Kopet Dag Mountains, whereas regions of lower topography/deformation (e.g., central Iran and the Lut Block), and the regions of younger deformation such as the Makran Accretionary Wedge and the Zagros Simply Folded Belt (SFB) have a thinner (<45 km) crust. Our model reveals a low‐Vs tongue‐shaped feature, indicating the underthrusting of the Arabian crust beneath central Iran. In the central Zagros, the underthrusting of the Arabian crust is steeper, resulting in a narrower deforming zone (∼150 km) and a thicker crust (∼60–65 km), compared to the NW or SE Zagros where the deforming zone is broader (∼250 km) and the crust is thinner (∼55–60 km). Regions of low‐Vs in the upper crust correspond to regions of thick sediments; the South Caspian Basin, the Zagros SFB and foreland basin of the Zagros, and the Makran Subduction Wedge. The subcrustal Rayleigh wave azimuthal anisotropy of the Plateau shows a rather uniform and smoothly‐varying pattern. In the NW Zagros the crustal and subcrustal pattern of anisotropy agrees with that previously estimated from the shear‐wave core phases, implying that the whole lithosphere deforms coherently, but for other regions (e.g., the western Alborz and Kopet Dag), the anisotropic pattern does not support a coherent deformational fabric throughout the lithosphere.

Growth of oriented orthotropic structures with reaction/diffusion

Lattice structures can present advantageous mechanical properties while remaining remarkably lightweight. Precise lattice design can however be tricky to set up with classical 3D modeling methods as it involves very fine details. Interestingly, natural porous structures can present such lattice-like or membrane-like features which motivates to seek for more bio-inspired approaches to microstructure design. In this paper, we present a novel method to grow lattice-like and membrane-like structures within an arbitrary shape and aligned along an oriented field. Our method relies on the use of a dedicated anisotropic reaction–diffusion system guided by an orthotropic diffusion tensor field. Assuming for instance the diffusion tensor to be related to the stress analysis of a given shape allows to generate emerging stripes patterns aligned along each one of the principal stress directions independently. A globally coherent mechanical model conforming to the initial shape boundary and infilled with oriented microstructures can therefore be synthesized. Further, we demonstrate the capability of this approach to handle other types of oriented fields such as obtained through optimization of material directions in scenarios with multiple load cases. Our approach relies on spatially and temporally local operations allowing for efficient parallelization. This permits user-interaction and automated adaptation of the design, even for fine meshes over large volumes. For instance, a designer can locally erase or “draw” over the structure and let it regrow and adapt as well as enforce regions to be deliberately full or empty. The proposed approach yields smooth and conformal oriented anisotropic geometrical patterns. This is related to recent effort in the structural optimization community on the topic of optimized oriented infills and microstructure de-homogenization. One of the resulting designs is validated by means of a full scale general non-linear analysis showcasing the advantageous properties of oriented microstructures for stability and robustness to buckling.

Alpine Fault‐Related Microstructures and Anisotropy of the Mantle Beneath the Southern Alps, New Zealand

AbstractMantle xenoliths from the Southern Alps, New Zealand, provide insight into the origin of mantle seismic anisotropy related to the Australian‐Pacific plate boundary. Most xenoliths from within 100 km lateral distance of the Alpine Fault are coarse grained, but a small number are finer grained protomylonites. The protomylonites contain connected networks of fine grains with a different crystallographic preferred orientation (CPO) to coarse porphyroclasts in the same xenolith, suggesting that protomylonites and coarse‐grained samples record different deformation kinematics. The CPOs of fine grains in protomylonites have monoclinic symmetry, with the 2‐fold rotation axis normal to a plane that contains olivine [010] and orthopyroxene [100] maxima, suggesting that the protomylonite deformation involved significant simple shear. Some coarse‐grained samples contain unconnected lenses and layers of fine grains with the same CPO as the coarse grains. Microstructures suggest that these fine grains formed by subgrain rotation recrystallization and that protomylonites may represent an up‐strain progression of this microstructure, where the connectivity of fine grains has allowed them to localize shear and develop a new Alpine Fault CPO. The samples tell us about the state of the mantle at 25 Ma, in the early history of the plate boundary. If this suite of samples is representative of the mantle beneath the Alpine Fault in the present day, then we can interpret the complex seismic anisotropy patterns in the lithospheric mantle as representative of blocks containing variably rotated older CPOs juxtaposed by narrow shear zones associated with Alpine Fault deformation.

Crust-mantle decoupling beneath Afar revealed by Rayleigh-wave tomography

The Afar triple junction accustoms the diverging plate dynamics between the Arabian, Nubian, and Somalian plates along the Red Sea, Gulf of Aden, and East African rifts. The average anisotropy obtained from shear-wave splitting measurements agrees with the surface motion recovered by geodetic analyses. However, the vertical layering of anisotropy in this region is yet to be accurately determined. Here, we use earthquake seismic data to map Rayleigh-wave azimuthal anisotropy in the crust and lithospheric mantle beneath the East African Rift System. Our results suggest that a layering of anisotropy is present around the East African Rift System. At shorter periods that sample the crust, rift-parallel anisotropy is present in the vicinity of the rift, but in the central part of the rift, rift-normal anisotropy is found. At longer periods, sampling the lithospheric mantle, the anisotropic pattern is quite different. These observations suggest that the crust and lithospheric mantle are mechanically decoupled beneath the environs of the East African Rift System. Similarly, these results suggest complex dynamics within the crust and lithosphere in the region of the Afar triple junction.

Construction of Biomimetic Tissues with Anisotropic Structures via Stepwise Algorithm-Assisted Bioprinting.

Tissue-specific natural anisotropic microstructures play an important role in the normal functioning of tissues, yet they remain difficult to construct by current printing techniques. Herein, a stepwise algorithm-assisted bioprinting technology for the construction of biomimetic tissues with a customizable anisotropic microstructure by combining the Adaptive Mesh Generation algorithm and the Greedy Search algorithm is developed. Based on the mechanical topology optimization design mechanism, the Adaptive Mesh Generation algorithm can generate controllable anisotropic mesh patterns with the minimum free energy in plane models according to tissue-specific requirements. Subsequently, the Greedy Search algorithm can program the generated pattern data into optimized printing paths, effectively avoiding structural deformations caused by the multiple stacking of materials and reducing the printing time. The developed bioprinting technique is suitable for various types of bioinks including polymers, hydrogels, and organic/inorganic complexes. After combining with a calcium phosphorus bioink, the compound algorithm-assisted bioprinting technique successfully customizes femurs with biomimetic chemical compositions, anisotropic microstructures, and biological properties, demonstrating its effectiveness. Additionally, algorithm-assisted bioprinting is generally suitable for most commercial extrusion bioprinters that function in the geometric code (G-code) drive mode. Therefore, the algorithm-assisted extrusion bioprinting technology offers an intelligent manufacturing strategy for the customization of anisotropic microstructures in biomimetic tissues.

Three-Dimensional Printing of Dipeptides with Spatioselective Programming of Crystallinity for Multilevel Anticounterfeiting.

The functionalities of peptide microstructures and nanostructures can be enhanced by controlling their crystallinity. Gaining control over the crystallinity within the desired structure, however, remains a challenge. We have developed a three-dimensional (3D) printing method that enables spatioselective programming of the crystallinity of diphenylalanine (FF) dipeptide microarchitectures. A femtoliter ink meniscus is used to spatially control reprecipitation self-assembly, enabling the printing of a freestanding FF microstructure with programmed shape and crystallinity. The self-assembly crystallization of FF can be switched on and off at will by controlling the evaporation of the binary solvent. The evaporation-dependent crystallization was theoretically studied by the numerical simulation of supersaturation fields in the meniscus. We found that a 3D-printed FF microarchitecture with spatially programmed crystallinity can carry a 3D digital optical anisotropy pattern, applicable to generating polarization-encoded anticounterfeiting labels. This crystallinity-controlled additive manufacturing will pave the new way for facilitating the creation of peptide-based devices.

Study on dynamic behaviors from non-circular dense granular jet impact

Dynamic behaviors of non-circular dense granular jets impacting a sufficiently large target are studied by experiment and DEM simulation. Effects of the granular jet velocity, particle diameter, and aspect ratio on the anisotropic pattern were investigated. Results show that the anisotropy of particle concentration of the granular sheet is enhanced with increasing aspect ratio. Interestingly, despite the significant differences in flux, the particle velocities are approximately consistent along the long and short axes. Unlike liquid, a dead zone is present in the impact zone, and the axial-to-radial transformation of the velocity is achieved by similar circular motion along the dead zone. Because the dead zone is adaptively adjusted with the cross section, the particle fluxes are anisotropic. Frequent collisions and frictions contribute to the homogenization of velocity in azimuths. Increasing particle diameter causes the enhancement of velocity fluctuations, the circular motion cannot be maintained and particles become scattered and isotropic. • The anisotropy in velocity and flux of particles from non-circular dense particle jet impact is characterized. • The effects of the velocity, aspect ratio, and particle diameter on anisotropy are assessed. • The mechanism of the anisotropy of the granular sheet is simulated by DEM.

New SKS splitting anisotropy measurements point to tearing beneath Central Italy

In the middle of the Mediterranean, the partly still active Apennines subduction system has been usually defined using tomographic images and available shear wave splitting measurements. In this paper we describe the new seismic anisotropy dataset for Central Italy, the region where the transition between Northern and Southern Apennines occurs. The new measurements show NW-SE fast polarisation directions beneath the belt, due to the retreat of the slab, NNE-SSW orientations from proper Adriatic mantle sources, and E-W directed anisotropy, attributed to mantle convection flow at the Thyrranian side. Additionally, the new data suggest the presence of a toroidal mantle flow through a tear in the Apenninic slab, from the Adria to the Tyrrhenian side. However, mantle circulation and flows, identified by the pattern of shear wave splitting results, seem different from what was proposed in previous geodynamic models. Indeed, our results support the presence of a vertical slab tear with limited dimension. In the geodynamic model we propose, the tear acts to accommodate a differential slab retreat. The slab partitioning results in a different pattern and strength of seismic anisotropy traced from the Central Apennines with respect to the adjacent Northern and Southern Apennines.

Unravelling the regulating role of stacking pattern on the tunable dipole, mechanical behavior and carrier mobility for asymmetric Janus SnSSe bilayer

Recently, Janus two-dimensional (2D) materials have attracted considerable interest because of the novel physical properties in view of reducing dimensionality and breaking reflection symmetry. With the help of first-principles calculations, the structural and mechanical, electronic structure and vertical dipole, and carrier mobility of SnSSe bilayer with different stacking patterns were comprehensively evaluated in this study. The calculations of binding energy and elastic constants demonstrate the experimental feasibility of SnSSe bilayer configurations with different stacking patterns. The bandgaps of SnSSe bilayer configurations can be regulated in the range of ~ 0.50 to ~ 0.75 eV due to the diversity of stacking patterns. Non-zero dipole moments induced built-in electric fields are found in SSnSe/SSnSe configurations, which unravels the dependence of the dipole moments on thickness and different stacking patterns. Additionally, the calculated carrier mobilities of SnSSe bilayer exhibits anisotropy and stacking pattern dependence, and the electron mobility can reach up to ~ 8513.63 cm2/V·s along the y-direction. Our present work would not only provide fundamental understanding of stacking dependence of dipole moment, mechanical behavior, and carrier mobility on asymmetric SnSSe bilayer, but also shed some light on the theoretical design of Janus SnSSe material within electronic, optoelectronic and thermoelectric applications.

Velocity and azimuthal anisotropy structures beneath the Dianzhong Block and its vicinity, SE Tibetan Plateau, revealed by eikonal equation-based traveltime tomography

The Dianzhong Block (DZB) located on the southeastern margin of the Tibetan Plateau is an important tectonic zone characterized by the intense flow of crustal material. Although it is widely accepted that materials originating from the Tibetan Plateau migrate southeastward in the DZB and its vicinity, the flow mechanism and subsurface structures remain controversial. Here, we image the subsurface velocity and azimuthal anisotropy structures beneath the DZB and its surroundings by using eikonal equation-based tomography to study the crustal flow and deformation mechanisms. In this study, we collect high-quality seismic data from 290 broadband seismic stations and manually pick a total of 31,981 first arrivals. Our tomographic results display prominent velocity anomalies and complex azimuthal anisotropy patterns. In the upper crust, our results reveal predominant high-velocity anomalies, which are related to the Emeishan large igneous province (ELIP) and the stable Simao Block. We find strong low-velocity anomalies beneath the DZB in the middle–lower crust. The low-velocity anomalies extend southward from the Xiaojinhe Fault (XJHF) to the Red River Fault (RRF) and then rotate southeastward to the east of the Xiaojiang Fault (XJF). In addition, the inverted fast velocity directions generally follow the strike of the low-velocity anomalies. Based on these findings, we consider the existence of middle–lower crustal flow inside the DZB. Three distinct features of azimuthal anisotropy in the middle-upper crust are found around the XJF reflecting complex deformation, which may indicate different factors controlling the deformation of the XJF from the north to the south. In the lower crust and uppermost mantle, the azimuthal anisotropy beneath the RRF is relatively complex, exhibiting two patterns: one perpendicular and another parallel to the fault.

Surface symmetry determination by a deep learning application of optical second-harmonic generation results

Optical second-harmonic generation (SHG) technique is widely used to characterize the structural symmetry of condensed matters not only for the bulk but also for the surface states. Since experimental results of the SHG anisotropy patterns often contain multiple contributions from bulk and surface states, a conventional regression process may not provide a unique solution about the symmetry of each part. With a given symmetry for the bulk state, we here develop a discriminator for the surface symmetry by exploiting neural architectures based on 1D convolution layers where simulation results of SHG anisotropy patterns are taken as learning sequence data. Since SHG experimental results have limited information for determining a unique symmetry out of several symmetry candidates, our discriminator consists of tens of neural architectures optimized with different hyperparameters. As a final output, the surface symmetry discriminator gives a weighted sum of results suggested from all the individual neural architectures. We demonstrate that the discrimination results of the deep learning approach agree well with those of the conventional regression method for GaAs and Bi2Se3.

Crustal anisotropy beneath southeastern Tibet inferred from directional dependence of receiver functions

The present study reveals depth-dependent crustal anisotropic signatures beneath southeastern Tibet. It is used to characterize the rheology of major faults and shear zones, which is important for understanding crustal deformation and geodynamic processes beneath the study area. The depth-dependent anisotropic orientations have been investigated based on the directional dependence of radial and tangential receiver functions (RFs). To achieve our objective, we first computed 3683 good-quality P-RFs from 174 teleseismic earthquakes (M ≥ 5.5) recorded within epicentral distance range of 30∘ to 90∘ at 70 seismic stations of the Eastern Syntaxis experiment (XE Network). After that, we employed the harmonic decomposition technique at each seismic station to retrieve the first (k = 0), second (k = 1) and third (k = 2) degree harmonics from the RF dataset. Our study characterizes the type (horizontal or plunging) of the symmetry axis. The anisotropic axes of the upper crust (0–20 km) appear to vary from approximately N-S to NE-SW. They are usually orthogonal to orientations of major faults and suture zones in the region, implying the effect of structure-induced anisotropy. It can be explained by regularly oriented cracks or macroscopic structure alignment along the major faults. The anisotropic orientations of the middle crust (20–40 km) are NE-SW to E-W direction, reflecting a different pattern than those estimated in the upper crust. The lower crustal (40–70 km) anisotropic pattern (E-W or ESE-WNW direction) exhibits distinct orientations than the upper and middle crust. The crystal preferred orientations (CPO) of the mica and amphibole minerals are likely to cause anisotropy observed at mid-to-lower crustal depth ranges, emphasizing the role of ductile deformation due to material movement towards the east underneath southeastern Tibet. Our results, along with S(K)KS and direct S-waves splitting signatures, suggest mid-to-lower crust and lithospheric mantle material movement towards the east, while the discrepancies in anisotropic symmetric axes directions may be indicative for the partial coupling between the crust and upper mantle beneath the region.

Stochastic stratigraphic modeling using Bayesian machine learning

Stratigraphic modeling with quantified uncertainty is an open question in engineering geology. In this study, a novel stratigraphic stochastic simulation approach is developed by integrating a Markov random field (MRF) model and a discriminant adaptive nearest neighbor-based k-harmonic mean distance (DANN-KHMD) classifier into a Bayesian framework. The DANN-KHMD classifier is effective for extracting anisotropic patterns from sparse and heterogeneous spatial categorical data such as borehole logs. The MRF parameters can be initially estimated roughly or customized (if site-specific knowledge is available). Later these parameters can be updated and regularized in an unsupervised manner with constraints from site exploration results in a Bayesian manner. Throughout the learning process, both the soil profile and the MRF parameters are updated in a probabilistic manner. The advantages of the proposed approach can be summarized into four points: 1) inferring stratigraphic profile and associated uncertainty in an automatic and fully unsupervised manner; 2) reasonable initial stratigraphic configurations can be sampled and hence lower the computational cost; 3) both stratigraphic uncertainty and model uncertainty are taken into consideration throughout the inferential process; 4) relying on no training stratigraphy images. To illustrate the effectiveness of the developed approach, two synthetic cases and three real-world cases are studied and the advantages of the new approach over existing approaches are demonstrated.

Biomimicked large-area anisotropic grooves from Dracaena sanderiana leaf enhances cellular alignment and subsequent differentiation

Cellular alignment is important for the proper functioning of different tissues such as muscles or blood vessel walls. Hence, in tissue engineering, sufficient effort has been made to control cellular orientation and alignment. It has been shown that micro-and nanoscale anisotropic topological features on cell culture substrates can control cellular orientation. Such substrates are fabricated using various lithography techniques such as photolithography and soft lithography. Although such techniques are suitable for creating patterns in small areas to establish a proof-of-concept, patterning large areas with intricate features is an unsolved problem. In this work, we report that a replica of the groove-like anisotropic patterns of the abaxial side of a Dracaena sanderiana (bamboo) leaf can be used for large-area patterning of cells. We imprinted the leaf on polydimethylsiloxane (PDMS) and characterised its surface topography using scanning electron microscopy. We further cultured bone marrow human mesenchymal cells (BM-hMSCs), skeletal muscle cells (C2C12), and neuroblastoma cells (SHSY5Y) on the patterned PDMS on which the cells orient along the direction of the grooved pattern. Further, we observed enhanced neuronal differentiation of SHSY5Y cells on biomimicked pattern compared to flat PDMS as measured by percentage of cells with neurites, neurite length and the expression of neuronal differentiation marker beta-III tubulin (TUJ1). This process is simple, frugal, and can be adopted by laboratories with resource constraints. This one-step technique to fabricate large-area anisotropic surface patterns from bamboo leaves can be used as a platform to study cellular alignment and its effect on various cellular functions, including differentiation.

Anisotropy with respect to the applied magnetic field of spin qubit decoherence times

Electron spin qubits are a promising platform for quantum computation. Environmental noise impedes coherent operations by limiting the qubit relaxation (T1) and dephasing (Tϕ) times. There are multiple sources of such noise, which makes it important to devise experimental techniques that can detect the spatial locations of these sources and determine the type of source. In this paper, we propose that anisotropy in T1 and Tϕ with respect to the direction of the applied magnetic field can reveal much about these aspects of the noise. We investigate the anisotropy patterns of charge noise, evanescent-wave Johnson noise, and hyperfine noise in hypothetical devices. It is necessary to have a rather well-characterized sample to get the maximum benefit from this technique. The general anisotropy patterns are elucidated. We calculate the expected anisotropy for a particular model of a Si/SiGe quantum dot device.

Tomographic Image Interpretation and Central-Western Mediterranean-Like Upper Mantle Dynamics From Coupled Seismological and Geodynamic Modeling Approach

The Central-Western Mediterranean (CWM) is one of the most complex tectonic setting on Earth. Episodes of slab rollback, break-off and tearing, the opening of back-arc extensional basins (i.e., Liguro-Provencal, Alborean, Algerian and Tyrrhenian basins), the presence of large mountain ranges, active volcanoes and violent earthquakes have made the Mediterranean an ideal environment to study a wide range of geodynamic processes and an important target for seismological studies (e.g, seismic tomography). Here we build a geodynamic model which, although it does not reproduce its exact tectonic structure (e.g., due to the limits of the numerical method, approximations in the initial setup, etc), presents multiple and geometrically complex subduction systems analogous to those found in the CWM. The tectonic evolution of this model is estimated with petrological-thermo-mechanical 3D simulations, then, we dynamically compute the upper mantle fabrics and seismic anisotropy as a function of the strain history and local P-T conditions. After comparing the model with SKS splitting observations in order to quantify the discrepancies with the true Central-Western Mediterranean, we use the elastic tensors predicted for the modeled configuration to perform 3D P-wave anisotropic tomography by inverting synthetic P-wave delay times. Using the geodynamic model as reference, we evaluate the capabilities of a recently developed seismic tomography technique to recover the isotropic anomalies and anisotropy patterns related to a complex subduction environment in different conditions, such as poor data coverage and bad data quality. We observe that, although P-wave tomography still remains a powerful tool to investigate the upper mantle, the reliability of the retrieved structures strongly depends on data quality and data density. Furthermore, the recovered anisotropic patterns are consistent with those of the target model, but in general an underestimation of the anisotropy magnitude in the upper mantle is observed. In the light of future developments, our study suggests that by combining micro- and macro-scale geodynamic simulations and seismological modeling of seismic anisotropy it will be possible to reproduce, at least to a first order, the tectonic evolution of real study regions (e.g., the Mediterranean) thus providing fundamental constraints on the processes that have contributed in shaping their current geological scenario.

A confined-etching strategy for intrinsic anisotropic surface wetting patterning

Anisotropic functional patterned surfaces have shown significant applications in microfluidics, biomedicine and optoelectronics. However, surface patterning relies heavily on high-end apparatuses and expensive moulds/masks and photoresists. Decomposition behaviors of polymers have been widely studied in material science, but as-created chemical and physical structural changes have been rarely considered as an opportunity for wettability manipulation. Here, a facile mask-free confined-etching strategy is reported for intrinsic wettable surface patterning. With printing technology, the surface wetting state is regulated, enabling the chemical etching of setting locations and efficient fabrication of complex patterns. Notably, the created anisotropic patterns can be used for realizing water-responsive information storage and encryption as well as fabricating flexible electrodes. Featuring advantages of simple operation and economic friendliness, this patterning approach brings a bright prospect in developing functional materials with versatile applications.

Interpretation of the Spectra and Anisotropy of Galactic Cosmic Rays

Recent measurements of the spectra and anisotropy of cosmic rays (CRs) show a fine structure that reflects the spectral hardenings of CRs nuclei at the rigidity R ∼ 200 GV followed by softenings at R ∼ 10 TV, and reveal complicated energy dependence of the amplitude and phase of anisotropy from 100 GeV to PeV. Numerous studies have shown that the existence of nearby CR sources and a local interstellar magnetic field (LIMF) near the solar system are crucial for such CR spectral and anisotropic patterns. In this work, we analyze the CR spectra of different CR components and the anisotropy considering the nearby Geminga supernova remnants (SNRs) source. In the calculation process, we also introduce the anisotropic diffusion of CRs induced by the LIMF based on the spatial-dependent propagation (SDP) model. As a result, our model can simultaneously account for the CR spectra and the anisotropy from 100 GeV to PeV. Future high-precision measurements of the CR anisotropy, for example, by the LHAASO experiment, would be of the essence in the assessment of our proposed model.

Slab Geometry and Upper Mantle Flow Patterns in the Central Mediterranean From 3D Anisotropic P-Wave Tomography.

We present the first three‐dimensional (3D) anisotropic teleseismic P‐wave tomography model of the upper mantle covering the entire Central Mediterranean. Compared to isotropic tomography, it is found that including the magnitude, azimuth, and, importantly, dip of seismic anisotropy in our inversions simplifies isotropic heterogeneity by reducing the magnitude of slow anomalies while yielding anisotropy patterns that are consistent with regional tectonics. The isotropic component of our preferred tomography model is dominated by numerous fast anomalies associated with retreating, stagnant, and detached slab segments. In contrast, relatively slower mantle structure is related to slab windows and the opening of back‐arc basins. To better understand the complexities in slab geometry and their relationship to surface geological phenomenon, we present a 3D reconstruction of the main Central Mediterranean slabs down to 700 km based on our anisotropic model. P‐wave seismic anisotropy is widespread in the Central Mediterranean upper mantle and is strongest at 200–300 km depth. The anisotropy patterns are interpreted as the result of asthenospheric material flowing primarily horizontally around the main slabs in response to pressure exerted by their mid‐to‐late Cenezoic horizontal motion, while sub‐vertical anisotropy possibly reflects asthenospheric entrainment by descending lithosphere. Our results highlight the importance of anisotropic P‐wave imaging for better constraining regional upper mantle geodynamics.