Tunneling effect in gapped graphene disk in magnetic flux and electrostatic potential

We investigate the tunneling effect of a Corbino disk in graphene in the presence of a variable magnetic flux Φi created by a solenoid piercing the inner disk under the effect of a finite mass term in the disk region (R1 < r < R2) and an electrostatic potential. Considering different regions, we explicitly determine the associated eigenspinors in terms of Hankel functions. The use of matching conditions and asymptotic behavior of Hankel functions for large arguments, enables us to calculate transmission and other transport quantities. Our results show that the energy gap suppresses the tunneling effect by creating singularity points of zero transmission corresponding to the maximum shot noise peaks quantified by the Fano factor F . The transmission as a function of the radii ratio R2/R1 becomes oscillatory with a decrease in periods and amplitudes. It can even reach one (Klein tunneling) for large values of the energy gap. The appearance of the minimal conductance at the points kF R1 = R1δ is observed. Finally we find that the electrostatic potential can control the effect of the band gap.

3D Monte Carlo analysis on photons step through turbid medium by Mie scattering

Photon Scattering Profiles in a turbid media were investigated through numerical simulation based on Monte Carlo-Mie method, at this present work. Using Wolfram Mathematics in the program algorithm. Photon Scattering was treated using electromagnetic spherical harmonics waves, in three-dimensional scattering. The proposal, as an alternative to the Henyey-Greensein phase approximation, was defining an unit vector that represents a phase distribution, as an equivalent function with three vector components, within the turbid media. Associating the step component, as projection using Legendre polynomials and for the transverse plane components were defining as vector bases in terms of Legendre-Hankel functions, according to Gustav Mie theory. This composite vector was defined as a step function and was evaluated within Monte Carlo algorithm, obtaining simulations of light scattering. Backscatter profiles were compared for different geometric dimensions of the spherical particles within the turbid media, including a validation of the model with an experimental Lidar signal from low clouds, obtaining physical properties of the turbid media by the proposed theoretical model.

Dynamic Stress-Deformed States of a Circular Tunnel of Small Position Under Harmonic Disturbances

There are many underground tunnels of various shapes located in seismically active areas that need to be protected from seismic impacts. The paper considers the impact of harmonic waves on a cylindrical shell located in a viscoelastic half-plane. The study's main purpose is to determine the stress-strain state of a cylindrical shell when exposed to harmonic waves. The basic equation of viscoelasticity in displacements with the corresponding boundary conditions is obtained. The problem posed is solved in mixed potentials that satisfy the wave equation with complex parameters. The solution is expressed in terms of special Bessel and Hankel functions. As a result of multiple reflections, a system of algebraic equations with complex coefficients is obtained. In the future, this system is solved by the Gauss method with the selection of the main element. The analytical solution is obtained in infinite series, the convergence of which is investigated numerically. The numerical results were obtained using the MATLAB software package. The reliability of the research results is confirmed by good agreement with theoretical and experimental results and those obtained by other authors.

On the Electromagnetic Field of an Overhead Line Current Source

This work presents an analytical series-form solution for the time-harmonic electromagnetic (EM) field components produced by an overhead current line source. The solution arises from casting the integral term of the complete representation for the generated axial electric field into a form where the non-analytic part of the integrand is expanded into a power series of the vertical propagation coefficient in the air space. This makes it possible to express the electric field as a sum of derivatives of the Sommerfeld integral describing the primary field, whose explicit form is known. As a result, the electric field is given as a sum of cylindrical Hankel functions, with coefficients depending on the position of the field point relative to the line source and its ideal image. Analogous explicit expressions for the magnetic field components are obtained by applying Faraday’s law. The results from numerical simulations show that the derived analytical solution offers advantages in terms of time cost with respect to conventional numerical schemes used for computing Sommerfeld-type integrals.

On the Flux Linkage between Pancake Coils in Resonance-Type Wireless Power Transfer Systems

This work presents a series representation for the mutual inductance of two coaxial pancake coils which remains accurate in non-quasi-static regime under the hypothesis that the current in the source coil is uniformly distributed. Making use of Gegenbauer’s addition theorem and a term-by-term analytical integration, the mutual inductance between two generic turns belonging to distinct coils is expressed as a sum of spherical Hankel functions with algebraic coefficients. The accuracy and efficiency of the resulting expression is proved through pertinent numerical examples.

Evaluation of Inverse Fourier Pressure Integrals for Finite Acoustic Sources on Cylindrical Baffles

For various types of finite acoustic sources placed on an infinite cylindrical baffle, the pressure solution in cylindrical coordinates can be given by an infinite series of Inverse Fourier Integrals involving a singular quotient of Hankel functions. A hybrid method is introduced addressing these integrals’ singularity analytically and truncating their infinite integration range with predictable error. Maximum number of significant terms to be taken into account is discussed and determined. Results are obtained for a wide range of dimensionless frequency values ([Formula: see text]–100) and observation point distances ranging from 3 to 100 radii of the cylindrical baffle. As an application, the baffle diffraction step of the infinite cylindrical baffle is evaluated for the on-axis pressure of a uniformly-vibrating piston.