scholarly journals Axial-Symmetric Diffraction Radiation Antenna with a Very Narrow Funnel-Shaped Directional Diagram

2021 ◽  
Vol 11 (21) ◽  
pp. 10381
Author(s):  
Yuriy Sirenko ◽  
Seil Sautbekov ◽  
Merey Sautbekova ◽  
Nataliya Yashina ◽  
Nursaule Burambayeva ◽  
...  
Keyword(s):  
Surface Wave ◽  
Dielectric Waveguide ◽  
Symmetry Axis ◽  
Coherent Radiation ◽  
Diffraction Radiation ◽  
Spatial Harmonic ◽  
Axially Symmetric ◽  
Directional Diagram ◽  
Modeling And Analysis ◽  
Periodic Grating

The paper is focused on reliable modeling and analysis of axially symmetric radiators with a very narrow (throat) funnel-shaped radiation pattern. When such a diagram is formed, a wave analogue of Smith–Purcell coherent radiation is realized—the surface wave of a radial dielectric waveguide ‘sweeps out’ with its exponentially decaying part a concentric periodic grating, the fundamental spatial harmonic of which, propagating without attenuation in a direction close to the symmetry axis of the structure, generates a radiation field with the required characteristics.

MODELING AND ANALYSIS OF A FASTSCANNING DIFFRACTION RADIATION ANTENNA

2016 ◽  
Vol 75 (3) ◽  
pp. 189-199 ◽  
Author(s):  
N. Burambayeva ◽  
V. Naumenko ◽  
S. Sautbekov ◽  
Yurii Konstantinovich Sirenko ◽  
Alexey A. Vertiy
Keyword(s):  
Diffraction Radiation ◽  
Modeling And Analysis

scholarly journals The Stationary Concentrated Vortex Model

Climate ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 39
Author(s):  
Oleg Onishchenko ◽  
Viktor Fedun ◽  
Wendell Horton ◽  
Oleg Pokhotelov ◽  
Natalia Astafieva ◽  
...  
Keyword(s):  
Vortex Structure ◽  
Radial Direction ◽  
Symmetry Axis ◽  
Outer Part ◽  
Vertical Direction ◽  
Axially Symmetric ◽  
New Model ◽  
Vortex Model ◽  
Axis Of Symmetry ◽  
Good Agreement

A new model of an axially-symmetric stationary concentrated vortex for an inviscid incompressible flow is presented as an exact solution of the Euler equations. In this new model, the vortex is exponentially localised, not only in the radial direction, but also in height. This new model of stationary concentrated vortex arises when the radial flow, which concentrates vorticity in a narrow column around the axis of symmetry, is balanced by vortex advection along the symmetry axis. Unlike previous models, vortex velocity, vorticity and pressure are characterised not only by a characteristic vortex radius, but also by a characteristic vortex height. The vortex structure in the radial direction has two distinct regions defined by the internal and external parts: in the inner part the vortex flow is directed upward, and in the outer part it is downward. The vortex structure in the vertical direction can be divided into the bottom and top regions. At the bottom of the vortex the flow is centripetal and at the top it is centrifugal. Furthermore, at the top of the vortex the previously ascending fluid starts to descend. It is shown that this new model of a vortex is in good agreement with the results of field observations of dust vortices in the Earth’s atmosphere.

scholarly journals Направленные поверхностные акустические волны в нецентросимметричных решетках

2021 ◽  
Vol 55 (4) ◽  
pp. 308
Author(s):  
А.Н. Поддубный
Keyword(s):  
Spatial Distribution ◽  
Surface Wave ◽  
Acoustic Wave ◽  
Wave Vector ◽  
Bloch Wave ◽  
Interface Plane ◽  
Russian Science ◽  
Periodic Grating ◽  
Nonzero Mean ◽  
Nonzero Degree

Spatial distribution of surface Rayleigh acoustic wave propagating along the surface of GaAs semiconductor covered by a periodic grating of gold stripes is calculated. We demonstrated that when the lattice has no center of spatial inversion the distribution of deformation for the surface wave with the Bloch wave vector kx = 0 is asymmetric and characterized by nonzero mean momentum in the interface plane and nonzero degree of transverse polarization in the plane perpendicular to the surface. The work has been supported by the Russian Science Foundation Grant No. 20-12-00194.

scholarly journals Deprojection of Galaxies: How Much Can Be Learned?

1987 ◽  
Vol 127 ◽  
pp. 397-398 ◽  
Author(s):  
George B. Rybicki
Keyword(s):  
Symmetry Axis ◽  
Three Dimensional ◽  
Light Distribution ◽  
Axially Symmetric ◽  
Simple Criterion ◽  
Slice Theorem ◽  
Intrinsic Shape ◽  
Model Independent ◽  
Fourier Slice Theorem

A general discussion, based on the ht “Fourier Slice Theorem,” is given for the problem of deprojecting the observed light distribution of galaxies to obtain their intrinsic three dimensional light distribution or “shape.” Several results are obtained: 1) A model-independent deprojection of an axially symmetric galaxy is shown to be possible only if the symmetry axis lies in the plane of the sky. 2) A simple criterion is given to test whether two different galaxies can have the same intrinsic shape, based solely on their observed projections. 3) It is shown that a homogeneous class of galaxies can be deprojected using a sufficiently large number of projections of random perspective.

scholarly journals Relativistic Rotating Electromagnetic Fields

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
H. Vargas-Rodríguez ◽  
A. Gallegos ◽  
M. A. Muñiz-Torres ◽  
H. C. Rosu ◽  
P. J. Domínguez
Keyword(s):  
Electromagnetic Field ◽  
Electromagnetic Fields ◽  
Symmetry Axis ◽  
Poynting Vector ◽  
Momentum Density ◽  
Axially Symmetric ◽  
Speed Of Light ◽  
Vector Form ◽  
Magnetic Dipoles ◽  
Axis Of Symmetry

In this work, we consider axially symmetric stationary electromagnetic fields in the framework of special relativity. These fields have an angular momentum density in the reference frame at rest with respect to the axis of symmetry; their Poynting vector form closed integral lines around the symmetry axis. In order to describe the state of motion of the electromagnetic field, two sets of observers are introduced: the inertial set, whose members are at rest with the symmetry axis; and the noninertial set, whose members are rotating around the symmetry axis. The rotating observers measure no Poynting vector, and they are considered as comoving with the electromagnetic field. Using explicit calculations in the covariant 3 + 1 splitting formalism, the velocity field of the rotating observers is determined and interpreted as that of the electromagnetic field. The considerations of the rotating observers split in two cases, for pure fields and impure fields, respectively. Moreover, in each case, each family of rotating observers splits in two subcases, due to regions where the electromagnetic field rotates with the speed of light. These regions are generalizations of the light cylinders found around magnetized neutron stars. In both cases, we give the explicit expressions for the corresponding velocity fields. Several examples of relevance in astrophysics and cosmology are presented, such as the rotating point magnetic dipoles and a superposition of a Coulomb electric field with the field of a point magnetic dipole.

3-D modeling and analysis of meander-line-coil surface wave EMATs

Mechatronics ◽  
2012 ◽  
Vol 22 (6) ◽  
pp. 653-660 ◽  
Author(s):  
Shujuan Wang ◽  
Lei Kang ◽  
Zhichao Li ◽  
Guofu Zhai ◽  
Long Zhang
Keyword(s):  
Surface Wave ◽  
Modeling And Analysis ◽  
Meander Line
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