This work analytically and numerically investigates the effect of a slightly rough surface with a Gaussian profile on the scattering coefficients and corresponding shielding effectiveness (SE) for a finite-width slab immersed in air. The Gaussian profile is modeled using the Small Perturbation Method, which is employed to calculate the bistatic scattering and transmission coefficients, along with the SE, for both parallel and perpendicular polarizations. Initially, the considered framework is modeled for a conventional copper slab, yielding an analysis in the radio frequency range. To explore higher-frequency regimes, the investigation is extended into the far-infrared and near-infrared regions by incorporating graphene, which exhibits an exceptionally adjustable optical response. To this end, a finite number of graphene sheets are integrated – modeling it as a homogeneous, isotropic slab with a complex permittivity that is implicitly dependent on the incident frequency, chemical potential, temperature, and number of graphene sheets. Additionally, the effects of variation in roughness parameters, namely height h, correlation length l c , and scattering angles, are examined for both cases: with and without graphene integration. Furthermore, the proposed methodology is numerically validated against previously published results, demonstrating strong agreement with established findings. The results reveal how graphene's tunable properties and surface roughness collectively influence scattering behavior, offering design guidelines for graphene-based optical devices and temperature-sensing applications across extended frequency ranges.

A uniform geometrical theory of diffraction (UTD) solution was developed earlier for radiation from sources on an analytically defined conducting convex surface. However, its application to meshed surfaces is challenging since it requires geodesic ray tracing and geometry based parameter extraction needed by UTD. The geodesic ray tracing algorithm, and the closed-form expressions and algorithms for geometry-based parameter extraction, which were developed previously for the UTD solution for mutual coupling, are modified accordingly for the application of the UTD solution for radiation to predict near and far fields from a source on a triangulated convex surface. Values for the geometry based parameters extracted from a triangulated circular cylinder and a triangulated sphere are compared with their actual values for validation. Although the proposed approach is applicable to triangulated arbitrary conducting convex surfaces, near and far field results obtained by applying the UTD solution to the analytically defined circular cylinder and sphere are respectively used to validate the results for the triangulated surfaces for these geometries. UTD is the only asymptotic method that includes creeping rays. Hence, the proposed approach is critically important for applications where creeping rays provide a significant contribution to fields radiated into or near shadow regions.

The Love waves propagation in a micro-waveguide loaded with a biopolymer is investigated analytically. In this article, the small-scale effect in the micro-waveguide is introduced using successively second gradient model with a negative sign and second gradient model with a positive sign. Furthermore, the biopolymer viscoelasticity is depicted by the Zener fractional model. A dispersion equation derived from appropriate boundary conditions is used to determine the Love wave velocity and attenuation. The effect of the strain gradient model, waveguide thickness, frequency and derivative order on the Love wave velocity and attenuation are investigated. The obtained results show that the damping frequency band decreases as the derivative order increases. These investigations are fundamental for designing Love wave sensors intended to characterize media with complex rheological properties as biopolymers. In addition, this study can be very useful to interpret the experimental measurements.

This investigation centers on the analysis of horizontally polarized shear wave (SH-wave) behavior in an irregular piezoelectric–viscoelastic layer positioned atop a piezoelectric–viscoelastic substrate. The framework of this study also encompasses the use of perturbation technique solution of first order, the non-dimensional aspects of the resulting equations of motion, and the grooved boundary conditions that emerge from the modeled problem. Considering that the irregularities are extremely small, we maintain upto first order terms. The dispersion equations for SH-wave propagation have been established for both electrically open (EO) and short (ES) conditions with the aid of supportable boundary conditions. The influence of various parameters on the dispersion relations and SH-wave velocity profile has been examined by numerical examples and graphical demonstrations. The effects of viscoelasticity and electric constants are remarkable in the dynamics of the wave distribution profiles of the material. It is crucial to state that the presence of irregularity negatively affects velocity profile of the wave for both electrical conditions. For the analysis and design of SAW devices made of piezoelectric materials, this work may offer theoretical insight. Also, researchers in the fields of geophysics, industrial engineering, material sciences, amongst others should be able to find the work helpful.

In this paper, the second harmonic generation of the laser beam in a parabolic plasma channel has been studied. The intensity profile of the higher modes of Laguerre–Gaussian laser beam propagating in plasma having relativistic-ponderomotive nonlinearity has been taken into account. Ponderomotive effects occur for lasers having strong intensity gradients while relativistic effects come into existence when plasma electron oscillation velocity approaches light's velocity. When a laser beam propagates in such plasma, it modifies the plasma's dielectric function and excites an electron plasma wave (EPW). In-phase mixing of the incoming laser beam with EPW generates second harmonics of the incident beam. The expression for self-focusing of laser in plasma has been obtained by the method of moments and WKB approximation. It has been observed that the higher modes of laser beam, density ramp and plasma channel play an important role for enhancing the second harmonic yield under the combined effect of relativistic-ponderomotive nonlinearity.

Closed-form expressions were recently derived for depolarization dyadics for truncated spheres and truncated spheroids, and the formalism was extended to truncated ellipsoids. These results were exploited to develop an implementation of the Maxwell Garnett homogenization formalism for the relative permittivity parameters of homogenized composite mediums (HCMs) arising from an isotropic host medium impregnated with isotropic inclusions that are truncated spheres, spheroids, and ellipsoids. In so doing, the anisotropy of the HCM was related to the geometry of the inclusions: in general, the more the shape of the inclusions deviated from spherical, the greater was the degree of anisotropy exhibited by the HCM.

The present paper is concerned with a theory of thermoelasticity based upon a newly developed temperature-rate-dependent thermoelastic model that was proposed by Yu et al. [Meccanica. 2018;53:2543–2554], which has eliminated the discontinuity observed in the displacement field during transient motion. The basic governing equations for a homogeneous and isotropic medium are formulated to deduce the significant theorems. Firstly, we prove the uniqueness theorem concerning a mixed initial and boundary value problem within the framework of linear thermoelasticity. Furthermore, we establish a reciprocity theorem utilizing the Laplace transform, which provides insight into the mutual influence between different aspects of the system under consideration. Consequently, we proved the Somigliana and Green theorems. This generalized theorem extends the applicability and versatility of the classical theorems and also assists the issue of thermal and mechanical fields as well as is beneficial for geophysics and mining.

Propagation properties of plasma-filled PPWG surrounded by BP layers are explored in this research. Field equations are derived with the help of Maxwell’s equations. Boundary conditions x = d / 2 and x = − d / 2 are applied to obtain the characteristic equation for transverse magnetic (TM) mode. The influence of plasma frequency, electron doping, number of BP layers and core width on effective mode index are analyzed for armchair and zigzag conductivity of BP in the THz frequency range. It is concluded that armchair conductivity has a higher effective mode index compared to the zigzag conductivity of BP for the proposed waveguide structure. The presented results may have potential applications to fabricate black phosphorus-based nanophotonic devices in the THz frequency range.