Dispersion properties of artifi cial topological insulators based on an infi nite double-periodic array of elliptical quartz elements

Subject and Purpose. Special features of all-dielectric electromagnetic analogues of topological insulators (TI) in the microwave range are considered, aiming at studying the influence of geometrical and constitutive parameters of TI elements on the dispersion properties of topological insulators based on a two-dimensional double-periodic array of dielectric elements. Methods and Methodology. The evaluation of dispersion properties and electromagnetic field spatial distribution patterns for topological insulators is performed using numerical simulation programs. Results. The electromagnetic analogue of a topological insulator based on a double-periodic array of elliptical quartz cylinders has been considered. By numerical simulation, it has been demonstrated that the electromagnetic properties of the structure are controllable by changing the quartz uniaxial anisotropy direction without any changes in other parameters. A combined topological insulator made up of two adjoining ones differing in shapes of their unit cells has been considered with the numerical demonstration that frequencies of surface states are controllable by choosing the quartz uniaxial anisotropy direction. It has been shown that it is at the interface of two different in shape unit cells that the electromagnetic field concentration at a surface state frequency takes place. Conclusion. A possibility has been demonstrated of controlling microwave electromagnetic properties of topological insulators by changing their geometric parameters and permittivity of the constituents. From a practical point of view, topological insulators can be used as components of microwave transmission lines and devices featuring very small propagation loss.

Investigation of anisotropic spatial correlations of intra-event residuals of multiple earthquake intensity measures using latent dimensions method

SUMMARY Considering spatial correlation of multiple earthquake intensity measures (IMs) is of particular importance in loss assessment of spatially distributed assets. This subject has been investigated in previous studies under the assumption of isotropy. Considering the fact that the assumption of isotropy is not valid in general, the present study employs a non-separable covariance model based on latent dimensions method to investigate anisotropic properties of spatial correlations and cross-correlations of intra-event residuals of multiple earthquake IMs. This method leads to the generation of valid covariance matrix in order to model anisotropic spatially distributed multivariate random fields. Two sets of IMs are considered in this study; the first set consists of peak ground intensity values (acceleration, velocity, and displacement), and the second set consists of spectral accelerations at three different periods. Data of 10 earthquake events in California and Japan are utilized in this study to estimate parameters of marginal and cross-covariance models. Moreover, parameters of covariance model of regional site condition, which is considered as average shear wave velocity of top 30 m of soil profile (Vs30), are obtained in order to investigate the effect of local sited conditions on spatial correlations of IMs. It is shown that maximum range and anisotropy ratio of covariance models of intra-event residuals of IMs are correlated with those of Vs30 values. Also, it is observed that the anisotropy direction of residuals of IMs is consistent with anisotropy direction of Vs30 values. Finally, predictive models are proposed to obtain marginal and cross-covariance functions for different earthquake IMs considering anisotropy.

Where is seismic anisotropy located beneath the Alps and the Apennines?

<p>A general review on measurements of upper mantle seismic anisotropy in the Alpine and Apennines region is now encouraged by the large amount of data produced by several projects (i.e AlpArray, Cifalps1). Geodynamic studies need to have a sketch of mantle flows that drives the evolution of a<br>tectonically active region. This is particularly important for the Italian peninsula, where several slabs have been involved in the Alps and Apennines building and where they are still interacts with the Adriatic plate. Draw mantle flows starting from seismic anisotropy requires to locate the source of what SKS phases detect. The answer, often undetermined, it is frequently hypothesized cross-checking different seismological observation. Overlapping SKS data with tomographic models in this region gives little help, because of the large differences in the shape, depth and dimension of fast bodies identified by different tomographic studies. Mapping and comparing SKSs data with other types of anisotropy measurements (Pn anisotropy, azimuthal anisotropy from surface waves tomography, crustal anisotropy) allow to discretise where fast anisotropy direction is much more probably astenospheric or where it pervades also regions at shallower depths.</p>

Seepage, Deformation, and Stability Analysis of Sandy and Clay Slopes with Different Permeability Anisotropy Characteristics Affected by Reservoir Water Level Fluctuations

Evaluation of slope stability under water level fluctuations is an important topic in the Three Gorges Reservoir (TGR) in China. However, most of the previous studies regarded slope soil as isotropic material, or only considered the influence of anisotropy ratio (kr = kx/ky) but ignored the anisotropy direction (α). Meanwhile, the pore pressure–stress coupling was rarely considered in the previous numerical simulations. In the present study, the SIGMA/W and SLOPE/W modules in Geo-studio are utilized to carry out the numerical simulation of Caipo slope under the drawdown of the reservoir water level, and the anisotropy ratio (kr) as well as the anisotropy direction (α) of two kinds of soils (clay and sand) are included. Results show that the anisotropy ratio kr and anisotropy direction α decrease the infiltration capacity of the soil, which increases the infiltration line hysteretic elevation (ILHE) as well as maximum horizontal displacement (MHD), and reduces the minimum safety factor (MSF). The slope toe firstly fails with the drawdown of water level. The influence of reservoir water level drop on seepage, deformation, and stability of the sand slope is less than that of the clay slope. For the sandy soil slope, it is not only necessary to consider the influence of kr, but also the influence of α. For the soil slope, we can only consider α in order to simplify calculation.

A wavelet-based approach to quantify the anisotropy degree of spatial random point configurations

A two-dimensional point process, if considered as a random measure, can be expressed as a countable sum of Delta Dirac measures concentrated at some random points. Then a continuous wavelet transform can be applied to obtain information on some structural properties. We introduce the notions of wavelet-based isotropy, main anisotropy direction and anisotropy degree to characterize the implicit anisotropic structure of the point process. We propose several statistical hypothesis tests that are proved to be useful to test for the presence of anisotropy. An application to a real case is also included.