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Defects such as gaps, delamination, and the misalignment of fibres impair the performance of carbon fibre-reinforced composites and can lead to structural failure during operation. Eddy current testing has proven to be a suitable method for detecting these defects early in the manufacturing process. However, validated electromagnetic modelling techniques are required to develop new eddy current sensors and gain a better understanding of the eddy current signals caused by different defect sizes. This paper proposes a novel finite element modelling approach to better account for fibre heterogeneity using spline approximation. Further, adaptive mesh refinement is used to reduce FEM solution errors. A defect in the form of a gap is modelled by adjusting the spline approximation accordingly. Finally, the model also accounts for inter-laminar current paths between carbon fibre layers, which are determined by four-terminal resistance measurement. The results show that the electromagnetic properties of the structure can be successfully modelled. The simulation is validated by comparing the virtual scans with eddy current scans of dry carbon fibre fabric with and without artificially manufactured gaps.

Electrical-conductivity anomalies in subduction zones are believed to be strongly connected with global water cycling, volcanism and seismicity. However, the causal atomic-scale processes related to conductivity of rock-forming minerals in subducting rocks are virtually unknown. Here, in situ simultaneous high-temperature Raman spectroscopy and resistivity measurements on riebeckite as a model Fe-rich amphibole in subduction zones show that (1) electronic small polarons, with high mobility along the c -axis of the amphibole structure, activate above 500 K; (2) H + starts diffusing within the crystal above 650 K, although electron transport via polaron hopping is still the dominant mechanism of charge transfer; (3) the anisotropy in the conductivity is enhanced with increasing temperature, emphasizing the dominant role of e − over H + in causing the high conductivity (above 0.01 S/m) of Fe-rich amphiboles. We show that conductivity data obtained via magnetotelluric measurements are best modelled by considering the effect of stress-driven alignment of amphiboles during plate motion. Our results thus link atomic- and Earth-scale conductivity processes, significantly improving our understanding of subduction processes.

For certain shapes of inclusions embedded in a body, the field inside the inclusion is uniform for some boundary condition. We provide a construction scheme for inclusions of general shapes having such a uniformity property in two dimensions based on the conformal mapping technique for the potential problem. Using this complex analysis method, we also design nonelliptical neutral coated inclusions with anisotropic conductivity. Neutral coated inclusions do not perturb a background uniform field when they are inserted into a homogeneous matrix. Although coated inclusions of various shapes are neutral to a single field, only concentric ellipses or confocal ellipsoids can be neutral to all uniform fields. This paper presents our work relating to the construction of nonelliptical coated inclusions with anisotropic conductivity in two dimensions that are neutral to all uniform fields, where the assignment of the flux condition on the boundary of the core depends on the applied background field. Using these neutral inclusions, we obtain cylindrical neutral inclusions in three dimensions, with no flux applied to the boundary of the core and with the anisotropic conductivity function of the shell given in accordance with the background uniform field.

To investigate the influence of anisotropic electrical conductivity in white matter on the forward and inverse solution in electroencephalography (EEG) and magnetoencephalography (MEG) numerical simulation studies were performed. A high-resolution (1 mm3 isotropic) finite element model of a human head was implemented to study the sensitivity of EEG and MEG source localization. In vivo information on the anisotropy was obtained from magnetic resonance diffusion tensor imaging and included into the model, whereas both a direct transformation and a direct transformation with volume normalization were used to obtain conductivity tensors. Additionally, fixed artificial anisotropy ratios were also used, while considering only the orientation information from DTI, to generate conductivity tensors. Analysis was performed using over 25,000 single dipolar sources covering the full neocortex. Major findings of the study include that EEG is more sensitive to anisotropic conductivities in white matter compared to MEG. Especially with the inverse analysis, we found that sources placed deep in sulci are located more laterally if anisotropic conductivity of white matter tissue is neglected. Overall, the single-source localization errors resulting from a neglect of anisotropy were found to be smaller compared to errors associated with other modeling errors, like misclassified tissue or the use of nonrealistic head models. In contrast to the small localization error we observed significant changes in magnitude and orientation. The latter is important since dipole orientation might be more important than absolute dipole localization in assigning, e.g., epileptic activity to the wall of the affected brain sulcal area. If high-resolution finite element models are used to perform source localization in EEG and MEG experiments and the quality of the measured data permits localization accuracy of 1 mm and below, the influence of anisotropic compartments has to be taken into account.

Soft nano electronic materials based on conductive hydrogels have attracted considerable attention due to their exceptional properties. Particle deposition and poor interface compatibility often diminish the mechanical strength and electron transport capabilities of the conductive hydrogel. Mechanical damage can severely impact the performance of the conductive hydrogel and can even damage electronic devices based on the conductive hydrogel. In the current study, a transparent nano-silica hydrogel is prepared by employing an extremely easy-to-operate method. This approach can preclude the deposition of particles via strong mechanical force. In addition, controlling the concentration of the reaction interface makes the hydrogel grow along the mechanical force in the direction with a special directional hole structure formed. The hydrogel is transparent, showing excellent self-healing properties—it can self-heal within 15 seconds. Remarkably, the hydrogel after self-healing maintains its performance. Moreover, it has excellent mechanical properties and can be stretched in length. Up to 1,200% of the original length, the tensile strength of the gel spline can reach 7 MPa. The viscosity of the hydrogel can reach 1.67 × 10 8 (MPs). In addition, a large amount of Na + in this hydrogel endow it a conductivity of 389 ε/cm. The conductivity of this hydrogel is adjustable result from the special pore structure. Lastly, the difference between the horizontal and vertical conductivity of the same sample can reach 3–4 times, thus this hydrogel can be used in the field of nano conductive materials.

Controlled-source electromagnetic (CSEM) surveys are moving increasingly toward realistic and complicated scenarios where the survey region may contain undulated topography, complex geometries, and electrical anisotropy media. In this paper, the adaptive finite element numerical method is employed to discrete the total electric field equation, which can provide precise electromagnetic (EM) responses even with a coarse initial mesh. The unstructured tetrahedral grid is employed to effectively address arbitrary irregular geometry and mountain terrain. Then, the flexible generalized minimum residual solver (FGMRES), auxiliary-space Maxwell pre-conditioner, and grid division technique were used to solve the large-scale linear system of equations, which can stably solve ill-conditioned problems using fewer computing resources. Finally, we conducted a numerical experiment via our newly proposed forward modeling scheme on a synthetic model with multi-contrast electrical anisotropy. It validated that accurate EM fields could be obtained against the semi-analytic solutions, and this iterative solver has good robustness for various anisotropic media. As a result, we have developed a state-of-the-art 3D CSEM anisotropic forward modeling engine, which can quickly and accurately deal with large-scale and complex geo-models.

The conductivity of brain tissues is not only essential for electromagnetic source estimation (ESI), but also a key reflector of the brain functional changes. Different from the other brain tissues, the conductivity of whiter matter (WM) is highly anisotropic and a tensor is needed to describe it. The traditional electrical property imaging methods, such as electrical impedance tomography (EIT) and magnetic resonance electrical impedance tomography (MREIT), usually fail to image the anisotropic conductivity tensor of WM with high spatial resolution. The diffusion tensor imaging (DTI) is a newly developed technique that can fulfill this purpose. This paper reviews the existing anisotropic conductivity models of WM based on the DTI and discusses their advantages and disadvantages, as well as identifies opportunities for future research on this subject. It is crucial to obtain the linear conversion coefficient between the eigenvalues of anisotropic conductivity tensor and diffusion tensor, since they share the same eigenvectors. We conclude that the electrochemical model is suitable for ESI analysis because the conversion coefficient can be directly obtained from the concentration of ions in extracellular liquid and that the volume fraction model is appropriate to study the influence of WM structural changes on electrical conductivity.

Motivated by advances in flexible electronic technologies and by the endeavour to develop non-destructive testing methods, this article analyses the capability of computational multiscale formulations to predict the influence of microscale cracks on effective macroscopic electrical and mechanical material properties. To this end, thin metal films under mechanical load are experimentally analysed by using in-situ confocal laser scanning microscopy (CLSM) and in-situ four point probe resistance measurements. Image processing techniques are then used to generate representative volume elements from the laser intensity images. These discrete representations of the crack pattern at the microscale serve as the basis for the calculation of effective macroscopic electrical conductivity and mechanical stiffness tensors by means of computational homogenisation approaches. A comparison of simulation results with experimental electrical resistance measurements and a detailed study of fundamental numerical properties demonstrates the applicability of the proposed approach. In particular, the (numerical) errors that are induced by the representative volume element size and by the finite element discretisation are studied, and the influence of the filter that is used in the generation process of the representative volume element is analysed.

We study thrust production in a single-fluid magnetohydrodynamic (MHD) thruster with Hall-type coaxial geometry and show how velocity–field alignment and magnetic topology set the operating regime. Starting from the momentum equation with anisotropic conductivity, the axial Lorentz force density reduces to fz=σθzEzBr(χ−1), with the motional-field ratio χ≡(uBr)/Ez. Hence, net accelerating force (fz>0) is achieved if and only if the motional electric field Em=uBr exceeds the applied axial bias Ez (χ>1), providing a compact, testable design rule. We separate alignment diagnostics (cross-helicity hc=u·B) from the thrust criterion (χ) and generate equation-only axial profiles for χ(z), jθ(z), and fz(z) for representative parameters. In a baseline case (Ez=150Vm−1,σθz=50Sm−1,u0=12kms−1,Br0=0.02T,L=0.10m), the χ>1 band spans ≈21.2% of the channel; a lagged correlation peaks at Δz★≈8.82mm(CHU=0.979), and ∫0Lfzdz is slightly negative—indicating that enlarging the χ>1 region or raising σθz are effective levers. We propose a reproducible validation pathway (finite-volume MHD simulations and laboratory measurements: PIV, Hall probes, and thrust stand) to map fz versus χ and verify the response length. The framework yields concrete design strategies—Br(z) shaping where u is high, conductivity control, and modest Ez tuning—supporting applications from station-keeping to deep-space cruise.

Directional control of heat flow is essential for advanced energy and electronic systems, yet strategies for tuning anisotropic phonon transport in low-dimensional materials remain limited. Hollow tellurium (Te) nanowires were synthesized via a solvothermal method and modified through Pd electroless plating to achieve tunable anisotropic thermal transport. Structural analyses confirmed Pd incorporation as nanoscale surface deposits without crystalline Pd phases, while SEM observations revealed cavity enlargement due to galvanic displacement at higher PdCl2 concentrations. Bulk films prepared by cold pressing exhibited direction-dependent behavior. Thermal conductivities remained nearly unchanged below 2.2 mM PdCl2, but at 5.5 mM, the in-plane value increased to 2.14 W/(m·K) and the cross-plane value decreased to 0.39 W/(m·K), enhancing the anisotropy ratio from 2.71 to 5.49. This divergence arises from direction-selective phonon scattering, where Pd-rich regions promote in-plane heat flow while junction irregularity suppresses cross-plane transport. These results demonstrate a controllable approach for engineering anisotropic thermal properties in functional energy materials.