scholarly journals Acoustic integrated extinction

2015 ◽  
Vol 471 (2177) ◽  
pp. 20150008 ◽  
Author(s):  
Andrew N. Norris
Keyword(s):  
Plane Wave ◽  
Cross Section ◽  
Acoustic Scattering ◽  
Forward Direction ◽  
Time Dependent ◽  
Incident Plane Wave ◽  
Scattering Function ◽  
Long Wavelength ◽  
Incident Plane ◽  
Finite Integral

The integrated extinction (IE) is defined as the integral of the scattering cross section as a function of wavelength. Sohl et al. (2007 J. Acoust. Soc. Am. 122 , 3206–3210. ( doi:10.1121/1.2801546 )) derived an IE expression for acoustic scattering that is causal, i.e. the scattered wavefront in the forward direction arrives later than the incident plane wave in the background medium. The IE formula was based on electromagnetic results, for which scattering is causal by default. Here, we derive a formula for the acoustic IE that is valid for causal and non-causal scattering. The general result is expressed as an integral of the time-dependent forward scattering function. The IE reduces to a finite integral for scatterers with zero long-wavelength monopole and dipole amplitudes. Implications for acoustic cloaking are discussed and a new metric is proposed for broadband acoustic transparency.

Diffraction of a cylindrical pulse by a metallic half plane

1980 ◽  
Vol 58 (4) ◽  
pp. 433-442
Author(s):  
A. Chakrabarti ◽  
V. V. S. S. Sastry
Keyword(s):  
Plane Wave ◽  
Half Plane ◽  
Time Dependent ◽  
Incident Plane Wave ◽  
Total Field ◽  
Time Harmonic ◽  
Incident Plane ◽  
Time Dependent Problem ◽  
General Time

A direct transform technique is applied to the initial and boundary value problem involving diffraction of a cylindrical pulse by a half plane, on which impedance type of boundary conditions must be met by the total field. The solution to the time harmonic incident plane wave is deduced as a particular case of the general time-dependent problem considered here and we avoid the Wiener–Hopf technique which leads to very complicated factorization and which masks the role of the impedance factor Z′ (a small quantity) in the expression for the scattered field.

scholarly journals Free space transmission lines in receiving antenna operation

2019 ◽  
Author(s):  
Reuven Ianconescu ◽  
Vladimir Vulfin
Keyword(s):  
Plane Wave ◽  
Cross Section ◽  
Incident Wave ◽  
Transmission Lines ◽  
Incident Plane Wave ◽  
Software Simulation ◽  
Incident Plane ◽  
Receiving Antenna ◽  
Scattering Matrices ◽  
Simulation Results

This work derives exact expressions for the voltage and current induced into a two conductors non isolated transmission lines by an incident plane wave. The methodology is to use the transmission line radiating properties to derive scattering matrices and make use of reciprocity to derive the response to the incident wave. The analysis is in the frequency domain and it considers transmission lines of any small electric cross section, incident by a plane wave from any incident direction and any polarisation. The analytic results are validated by successful comparison with ANSYS commercial software simulation results, and compatible with other published results.

scholarly journals Core-Shell Nano-Antenna Configurations for Array Formation with More Stability Having Conventional and Non-Conventional Directivity and Propagation Behavior

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 99
Author(s):  
Qaisar Hayat ◽  
Junping Geng ◽  
Xianling Liang ◽  
Ronghong Jin ◽  
Sami Ur Rehman ◽  
...  
Keyword(s):  
Plane Wave ◽  
Propagation Direction ◽  
Core Shell ◽  
Incident Plane Wave ◽  
Polarization Direction ◽  
Shell Nanoparticles ◽  
Incident Plane ◽  
Core Shell Nanoparticles ◽  
Coated Nanoparticle ◽  
2D Array

The enhancement of optical characteristics at optical frequencies deviates with the choice of the arrangement of core-shell nanoparticles and their environment. Likewise, the arrangements of core-shell nanoparticles in the air over a substrate or in liquid solution makes them unstable in the atmosphere. This article suggests designing a configuration of an active spherical coated nanoparticle antenna and its extended array in the presence of a passive dielectric, which is proposed to be extendable to construct larger arrays. The issue of instability in the core-shell nanoantenna array models is solved here by inserting the passive dielectric. In addition to this, the inclusion of a dielectric in the array model reports a different directivity behaviour than the conventional array models. We found at first that the combination model of the active coated nanoparticle and passive sphere at the resonant frequency can excite a stronger field with a rotated polarization direction and a propagation direction different from the incident plane-wave. Furthermore, the extended 2D array also rotates the polarization direction and propagation direction for the vertical incident plane-wave. The radiation beam operates strong multipoles in the 2D array plane at resonant frequency (behaving non-conventionally). Nevertheless, it forms a clear main beam in the incident direction when it deviates from the resonance frequency (behaving conventionally). The proposed array model may have possible applications in nano-amplifiers, nano-sensors and other integrated optics.

An accurate theory of X-ray coplanar multiple SRMS diffractometry

2018 ◽  
Vol 74 (6) ◽  
pp. 673-680 ◽  
Author(s):  
V. G. Kohn
Keyword(s):  
Synchrotron Radiation ◽  
Plane Wave ◽  
Experimental Setup ◽  
Incident Plane Wave ◽  
Instrumental Function ◽  
Multiple Diffraction ◽  
Double Crystal ◽  
X Ray ◽  
Double Crystal Monochromator ◽  
Incident Plane

The article reports an accurate theory of X-ray coplanar multiple diffraction for an experimental setup that consists of a generic synchrotron radiation (SR) source, double-crystal monochromator (M) and slit (S). It is called for brevity the theory of X-ray coplanar multiple SRMS diffractometry. The theory takes into account the properties of synchrotron radiation as well as the features of diffraction of radiation in the monochromator crystals and the slit. It is shown that the angular and energy dependence (AED) of the sample reflectivity registered by a detector has the form of a convolution of the AED in the case of the monochromatic plane wave with the instrumental function which describes the angular and energy spectrum of radiation incident on the sample crystal. It is shown that such a scheme allows one to measure the rocking curves close to the case of the monochromatic incident plane wave, but only using the high-order reflections by monochromator crystals. The case of four-beam (220)(331)({\overline {11}}1) diffraction in Si is considered in detail.

Currents and charges induced by a normally incident plane wave on single and crossed tubular cylinders withka= 2

Radio Science ◽  
1978 ◽  
Vol 13 (1) ◽  
pp. 107-119 ◽  
Author(s):  
R. W. P. King ◽  
D. J. Blejer ◽  
S.-K. Wan ◽  
R. W. Burton
Keyword(s):  
Plane Wave ◽  
Incident Plane Wave ◽  
Incident Plane
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