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Tytuł:
A spectral-based method for tissue characterization
Autorzy:
Wójcik, J.
Byra, M.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/331796.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
quantitative ultrasound
signal analysis
wave scattering
Opis:
Quantitative ultrasound methods are widely investigated as a promising tool for tissue characterization. In this paper, a novel quantitative method is developed which can be used to assess scattering properties of tissues. The proposed method is based on analysis of oscillations of the backscattered echo power spectrum. It is shown that these oscillations of the power spectrum are connected with the distances between scatterers within the medium. Two techniques are proposed to assess the scatterer’s distribution. First, we show that the inverse Fourier transform of the backscattered echo power spectrum corresponds to a histogram of the distances between scatterers. Second, the Hilbert-Huang transform is used to directly extract the power spectrum oscillations. Both methods are examined by means of a numerical experiment. A cellular gas model of a biological medium is considered. Results are presented and discussed. Both methods can be used to evaluate the scatterer’s distribution by means of the power spectrum oscillations.
Źródło:
Hydroacoustics; 2016, 19; 369-375
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic Wave Correlation Tomography of Time-Varying Disordered Structures
Autorzy:
Samelsohn, G.
Tapuchi, S.
Powiązania:
https://bibliotekanauki.pl/articles/177920.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
wave scattering
random media
time correlation
tomographic reconstruction
Opis:
An original model based on first principles is constructed for the temporal correlation of acoustic waves propagating in random scattering media. The model describes the dynamics of wave fields in a previously unexplored, moderately strong (mesoscopic) scattering regime, intermediate between those of weak scattering, on the one hand, and diffusing waves, on the other. It is shown that by considering the wave vector as a free parameter that can vary at will, one can provide an additional dimension to the data, resulting in a tomographic-type reconstruction of the full space-time dynamics of a complex structure, instead of a plain spectroscopic technique. In Fourier space, the problem is reduced to a spherical mean transform defined for a family of spheres containing the origin, and therefore is easily invertible. The results may be useful in probing the statistical structure of various random media with both spatial and temporal resolution.
Źródło:
Archives of Acoustics; 2018, 43, 4; 647-655
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Method of analytical regularization based on the static part inversion in wave scattering by imperfect thin screens
Autorzy:
Nosich, A.I.
Powiązania:
https://bibliotekanauki.pl/articles/309580.pdf
Data publikacji:
2001
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
wave scattering
imperfect boundary conditions
thin screens
regularization
Opis:
The paper is focussed on the development of the method of analytical regularization (MAR) in electromagnetic wave scattering and absorption by imperfect scatterers shaped as thin screens.
Źródło:
Journal of Telecommunications and Information Technology; 2001, 3; 72-79
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydrodynamic forces on a submerged horizontal circular cylinder in uniform finite depth ice covered water
Autorzy:
Sahu, M.
Das, D.
Powiązania:
https://bibliotekanauki.pl/articles/1839795.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
fala powierzchniowa
elektrodynamika
dyfrakcja fal
wave scattering
hydrodynamic forces
submerged cylinder
ice-covered water
Opis:
Hydrodynamic forces on a submerged cylinder in uniform finite depth ice-covered water is formulated by using the method of multipoles, the ice-cover being modelled as an elastic plate of very small thickness. The forces (vertical and horizontal) are obtained analytically as well as numerically and depicted graphically for various values of flexural rigidity of the ice-cover to show the effect of its presence. When the flexural rigidity and surface density of the ice-cover are taken to be zero, then the curves for the forces almost coincide with the curves for the case of uniform finite depth water with free surface.
Źródło:
International Journal of Applied Mechanics and Engineering; 2020, 25, 3; 219-227
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design, Manufacture and Characterization of an Acoustic Barrier Made of Multi-Phenomena Cylindrical Scatterers Arranged in a Fractal-Based Geometry
Autorzy:
Casteneira-Ibanez, S.
Rubio, C.
Romero-Garcia, V.
Sanchez-Perez, J. V.
Garcia-Raffi, L. M.
Powiązania:
https://bibliotekanauki.pl/articles/176662.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
acoustic arrays
acoustic attenuation
acoustic wave absorption
acoustic wave scattering
phononic crystals
acoustic barrier
physical effect of sound
Opis:
In this work we present the design and the manufacturing processes, as well as the acoustics standard- ization tests, of an acoustic barrier formed by a set of multi-phenomena cylindrical scatterers. Periodic arrangements of acoustic scatterers embedded in a fluid medium with different physical properties are usually called Sonic Crystals. The multiple scattering of waves inside these structures leads to attenuation bands related to the periodicity of the structure by means of Bragg scattering. In order to design the acoustic barrier, two strategies have been used: First, the arrangement of scatterers is based on fractal geometries to maximize the Bragg scattering; second, multi-phenomena scatterers with several noise con- trol mechanisms, as resonances or absorption, are designed and used to construct the periodic array. The acoustic barrier reported in this work provides a high technological solution in the field of noise control.
Źródło:
Archives of Acoustics; 2012, 37, 4; 455-462
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Water wave scattering by an infinite step in the presence of an ice-cover
Autorzy:
Ray, S.
De, S.
Mandal, B. N.
Powiązania:
https://bibliotekanauki.pl/articles/265982.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
fala wodna
pokrywa lodowa
aproksymacja Galerkina
water wave scattering
ice cover
infinite step
integral equation
Galerkin approximation
reflection and transmission coefficients
Opis:
The classical problem of water wave scattering by an infinite step in deep water with a free surface is extended here with an ice-cover modelled as a thin uniform elastic plate. The step exists between regions of finie and infinite depths and waves are incident either from the infinite or from the finite depth water region. Each problem is reduced to an integral equation involving the horizontal component of velocity across the cut above the step. The integral equation is solved numerically using the Galerkin approximation in terms of simple polynomial multiplied by an appropriate weight function whose form is dictated by the behaviour of the fluid velocity near the edge of the step. The reflection and transmission coefficients are obtained approximately and their numerical estimates are seen to satisfy the energy identity. These are also depicted graphically against thenon-dimensional frequency parameter for various ice-cover parameters in a number of figures. In the absencje of ice-cover, the results for the free surface are recovered.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 4; 157-168
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Scattering of interface wave by bottom undulations in the presence of thin submerged vertical wall with a gap
Autorzy:
Dolai, P.
Powiązania:
https://bibliotekanauki.pl/articles/265016.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
dyfrakcja fal
fala powierzchniowa
fala grawitacyjna
submerged vertical wall
perturbation analysis
interface wave scattering
sinusoidal bottom
Galerkin approximations
zero-order reflection coefficient
first-order reflection coefficient
Opis:
In this paper, the problem of interface wave scattering by bottom undulations in the presence of a thin submerged vertical wall with a gap is investigated. The thin vertical wall with a gap is submerged in a lower fluid of finite depth with bottom undulations and the upper fluid is of infinite height separated by a common interface. In the method of solution, we use a simplified perturbation analysis and suitable applications of Green’s integral theorem in the two fluid regions produce first-order reflection and transmission coefficients in terms of integrals involving the shape function describing the bottom undulations and solution of the scattering problem involving a submerged vertical wall present in the lower fluid of uniform finite depth. For sinusoidal bottom undulations, the first-order transmission coefficient vanishes identically. The corresponding first-order reflection coefficient is computed numerically by solving the zero-order reflection coefficient and a suitable application of multi-term Galerkin approximations. The numerical results of the zero-order and first-order reflection coefficients are depicted graphically against the wave number in a number of figures. An oscillatory nature is observed of first-order reflection coefficient due to multiple interactions of the incident wave with bottom undulations, the edges of the submerged wall and the interface. The first-order reflection coefficient has a peak value for some particular value of the ratio of the incident wavelength and the bottom wavelength. The presence of the upper fluid has some significant effect on the reflection coefficients.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 2; 303-322
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Features of light scattering by surface fractal structures
Autorzy:
Semchuk, O.
Grechko, L.
Vodopianov, D.
Kunitska, L.
Powiązania:
https://bibliotekanauki.pl/articles/1964137.pdf
Data publikacji:
2009
Wydawca:
Politechnika Gdańska
Tematy:
fractal
scattering
light
electromagnetic wave
scattering coefficient
rough surface
Opis:
The average coefficient of light scattering by surface fractal structures is calculated within the limits of the Kirchhoff method. A normalized band-limited Weierstrass function is presented for modeling 2D fractal rough surfaces. On the basis of the numerical calculation of the average scattering coefficient, scattering indicatrices diagrams are calculated for various surfaces and falling angles. An analysis of the diagrams leads to the following conclusions: the scattering is symmetric relatively to the plane of fall; the picture becomes complicated when the surface calibration degree is increased; the greatest intensity of a scattering wave is observed in the mirroring direction; there are other directions in which bursts of intensity are observed.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2009, 13, 3; 199-206
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of a tunable and switchable multi-wavelength bidirectional Brillouin-erbium fiber ring laser
Autorzy:
Wang, F.
Yuan, R. Y.
Powiązania:
https://bibliotekanauki.pl/articles/2033954.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Rayleigh scattering
stimulated Brillouin scattering
four-wave mixing
laser
laser optics
Opis:
A multi-wavelength bidirectional Brillouin-erbium fiber ring laser with switchable Brillouin frequency spacing (BFS) is proposed and experimentally demonstrated. In the presented Brillouin-erbium ring laser, including an optical amplifier and a highly nonlinear fiber, and without any optical isolator, due to Rayleigh scattering, stimulated Brillouin scattering, and cascaded four-wave mixing initiated successively by the Brillouin pump (BP) light, the odd- and even-order Stokes lines are generated and circulate in the opposite direction in the ring cavity. The BP light and Stokes-induced Rayleigh backscattering light also simultaneously circulate in the ring cavity. Only by adjusting BP power, the gain competition between Brillouin based Stokes and cavity modes’ oscillation can be controlled, the laser output can be conveniently switched between single BFS and odd- or even-order double BFS. In addition, under the certain BP power conditions, the proposed multi-wavelength Brillouin-erbium fiber laser also can realize switchable odd- or even-order Stokes generation and Stokes generation with single BFS, with an increasing wavelength number in turn, only by simply adjusting pump power of the erbium-doped fiber amplifier. Stability and wavelength tunability of the proposed multi-wavelength bidirectional Brillouin-erbium fiber ring laser are also investigated, respectively.
Źródło:
Optica Applicata; 2021, 51, 3; 375-389
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Non-plane wave scattering from a single eccentric circular inclusion - Part I: SH waves
Niepłaskie rozpraszanie fal od kołowego mimośrodowo osadzonego wtrącenia w materiale – część I: fale SH
Autorzy:
Weber, W.
Zastrau, B. W.
Powiązania:
https://bibliotekanauki.pl/articles/281878.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
non-plane waves
eccentric scatterer
scattering
SH wave
elastic wave
TRC
Opis:
In this contribution, an analytical formalism for investigating the scattering behaviour of a single multi-layered inclusion in a homogeneous isotropic matrix under the influence of non-plane elastic SH waves is derived. Herein, the inclusion is assumed to have a circular shape with its layers being eccentrically arranged. Numerical examples are performed with Textile Reinforced Concrete, a new building material in civil engineering. Within these investigations both shielding and amplification of SH waves is shown.
W pracy przedstawiono analityczny formalizm zagadnienia rozpraszania fal na pojedynczym, wielowarstwowymwtrąceniu materiałowym w izotropowej, jednorodnej strukturze osnowy poddanej działaniu niepłaskich fal spolaryzowanych w płaszczyźnie poziomej (fale typu SH). Założono, że wtrącenie ma kołowy kształt, a jego warstwy są rozmieszczone mimośrodowo. Zamieszczono rezultaty symulacji numerycznych na przykładzie nowego materiału budowlanego, jakim jest beton wzmacniany tekstyliami. Pokazano efekt ekranowania i wzmacniania fal SH w takiej strukturze.
Źródło:
Journal of Theoretical and Applied Mechanics; 2011, 49, 4; 1183-1201
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electromagnetic Scattering by a Cylinder in a Lossy Medium of an Inhomogeneous Elliptically Polarized Plane Wave
Autorzy:
Mangini, Fabio
Dinia, Lorenzo
Frezza, Fabrizio
Powiązania:
https://bibliotekanauki.pl/articles/309521.pdf
Data publikacji:
2019
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
electromagnetic scattering
inhomogeneous wave dispersion
vectorial cylindrical-harmonics
Opis:
In this paper, a rigorous theoretical approach, adopted in order to generalize the Vectorial CylindricalHarmonics (VCH) expansion of an inhomogeneous elliptically polarized plane wave, is presented. An application of the VCH expansion to analyze electromagnetic field scattered by an infinite circular cylinder is presented. The results are obtained using the so-called complex-angle formalism reaching a superposition of Vectorial Cylindrical-Harmonics. To validate the method, a Matlab code was implemented. Also, the validity of the methodology was confirmed through some comparisons between the proposed method and the numerical results obtained based on the Finite Element Method (FEM) in the canonical scenario with a single cylinder.
Źródło:
Journal of Telecommunications and Information Technology; 2019, 4; 36-42
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Finite Difference Analysis of Surface Wave Scattering by Underwater Rectangular Obstacles
Autorzy:
Szmidt, K.
Powiązania:
https://bibliotekanauki.pl/articles/241339.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
water wave
scattering of waves
finite difference method
Opis:
This paper deals with the problem of the scattering of surface water waves by underwater obstacles. The main goal of the investigations is to estimate the efficiency of such structures in protecting sea shelf zones from open sea waves. A useful measure of the protection is the ratio of the square of the amplitude of the transmitted wave to the square of the amplitude of the arriving wave. The problem is formulated in terms of the finite difference method. It is shown that the discrete approach to the problem leads to eigenvalue problems for two matrices resulting from the discrete description. As compared to analytical formulation, the discrete method may be convenient in application to unsteady problems and obstacles of complicated geometry.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2010, 57, 3-4; 179-198
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electromagnetic Scattering of Inhomogeneous Plane Wave by Ensemble of Cylinders
Autorzy:
Dinia, Lorenzo
Mangini, Fabio
Frezza, Fabrizio
Powiązania:
https://bibliotekanauki.pl/articles/309062.pdf
Data publikacji:
2020
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
electromagnetic scattering
inhomogeneous wave dispersion
lossy media
multi-cylinders scattering
vectorial cylindrical-harmonics
Opis:
The interaction between an ensemble of cylinders and an inhomogeneous plane wave is introduced and is determined, in the present paper, through a rigorous theoretical approach. Scattered electromagnetic field generated by an indefinite number of infinite circular cylinders is analyzed by the application of the generalized vector cylinder harmonics (VCH) expansion. The exact mathematical model relied upon to represent this scenario considers the so-called complex-angle formalism reaching a superposition of vectorial cylindrical-harmonics and Foldy-Lax Multiple scattering equations (FLMSE) to account for the multiscattering process between the cylinders. The method was validated by comparing the numerical results obtained with the use of the finite element method and a homemade Matlab code.
Źródło:
Journal of Telecommunications and Information Technology; 2020, 3; 86-92
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Components for differential cross-section with taking into account the polarization effects in elastic electron-deuteron scattering
Autorzy:
Zhaba, V. I.
Powiązania:
https://bibliotekanauki.pl/articles/1066249.pdf
Data publikacji:
2019
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
cross-section
deuteron
deuteron wave function
electron-deuteron scattering
Opis:
The components for differential cross-section was considered with taking into account the polarization effects in elastic electron-deuteron scattering. These characteristics are analyzed for angle of electron scattering θ = 70º and different momentums. The angular-momentum dependence of values components for differential cross-section have been evaluated in 3D format. The wave function of the deuteron in the coordinate representation for the Reid93 potential was applied to numerical calculations.
Źródło:
World Scientific News; 2019, 131; 279-286
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The variable phase approach: phase, amplitude and wave functions of the states for np- system for Argonne v18 potential
Autorzy:
Zhaba, V. I.
Powiązania:
https://bibliotekanauki.pl/articles/1070870.pdf
Data publikacji:
2019
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
amplitude function
phase function
phase shifts
single-channel scattering
variable phase approach
wave function
Opis:
Numerical calculations of the values of phase, amplitude and wave functions for the nucleon-nucleon potential Argonne v18 are carried out using the variable phase approach. Peculiarities of the behavior of these functions are described for coordinates up to 7 fm and with energies of interaction Еlab = 1; 50; 100; 150; 250; 350 MeV. 1S0-, 1P1-, 3P0-, 3P1-, 1D2-, 3D2-, 1F3-, 3F3-, 1G4-, 3G4- states for the np- system are considered. The obtained graphic materials for the indicated functions can help to give a better and more complete quantum mechanical representation of the scattering phase and scattering amplitudes for the neuron-proton scattering, as well as better understand and supplement the data for the problem of scalar amplitude and the full cross-section of the nucleon-nucleon scattering.
Źródło:
World Scientific News; 2019, 123; 161-180
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
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