Temat: wave scattering - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: A spectral-based method for tissue characterization
Autorzy:: Wójcik, J.
Byra, M.
Nowicki, A.
Tematy:: quantitative ultrasound
signal analysis
wave scattering; Pokaż więcej
Wydawca:: Polskie Towarzystwo Akustyczne
Powiązania:: https://bibliotekanauki.pl/articles/331796.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 2.

Tytuł:: Acoustic Wave Correlation Tomography of Time-Varying Disordered Structures
Autorzy:: Samelsohn, G.
Tapuchi, S.
Tematy:: wave scattering
random media
time correlation
tomographic reconstruction; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/177920.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 3.

Tytuł:: Method of analytical regularization based on the static part inversion in wave scattering by imperfect thin screens
Autorzy:: Nosich, A.I.
Tematy:: wave scattering
imperfect boundary conditions
thin screens
regularization; Pokaż więcej
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/309580.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 4.

Tytuł:: Hydrodynamic forces on a submerged horizontal circular cylinder in uniform finite depth ice covered water
Autorzy:: Sahu, M.
Das, D.
Tematy:: fala powierzchniowa
elektrodynamika
dyfrakcja fal
wave scattering
hydrodynamic forces
submerged cylinder
ice-covered water; Pokaż więcej
Wydawca:: Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:: https://bibliotekanauki.pl/articles/1839795.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 5.

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.
Tematy:: acoustic arrays
acoustic attenuation
acoustic wave absorption
acoustic wave scattering
phononic crystals
acoustic barrier
physical effect of sound; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/176662.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 6.

Tytuł:: Water wave scattering by an infinite step in the presence of an ice-cover
Autorzy:: Ray, S.
De, S.
Mandal, B. N.
Tematy:: fala wodna
pokrywa lodowa
aproksymacja Galerkina
water wave scattering
ice cover
infinite step
integral equation
Galerkin approximation
reflection and transmission coefficients; Pokaż więcej
Wydawca:: Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:: https://bibliotekanauki.pl/articles/265982.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 7.

Tytuł:: Scattering of interface wave by bottom undulations in the presence of thin submerged vertical wall with a gap
Autorzy:: Dolai, P.
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; Pokaż więcej
Wydawca:: Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:: https://bibliotekanauki.pl/articles/265016.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 8.

Tytuł:: Identification of an arbitrary shape rigid obstacle illuminated by flat acoustic wave using near field data
Identyfikacja sztywnej przeszkody o dowolnym kształcie oświetlonej płaską falą akustyczną przy użyciu danych z bliskiego pola
Autorzy:: Rymarczyk, Tomasz
Sikora, Jan
Tematy:: acoustics wave scattering by arbitrary shaped objects
simulation of external acoustic problems using the Boundary Element Method (BEM)
inverse problem
zagadnienie rozpraszania fal akustycznych przez obiekty o dowolnym kształcie
symulacja zewnętrznych zagadnień akustycznych Metodą Elementów Brzegowych (MEB)
zagadnienie odwrotne; Pokaż więcej
Wydawca:: Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Powiązania:: https://bibliotekanauki.pl/articles/58907946.pdf Link otwiera się w nowym oknie
Opis:: The inverse problem concerning the identification of rigid surfaces of scattering objects formulated in the frequency domain is presented in this paper. Differences in the identification of concave objects, such as kite-shaped, and convex objects (circle) are indicated. The reader’s attention is focused on the conventional boundary element method with small number of boundary elements and the small number of sensors, which is significant for inverse problems.
Zagadnienie odwrotne dotyczące identyfikacji sztywnych powierzchni obiektów rozpraszających sformułowanych w dziedzinie częstotliwości została przedstawiona w tej pracy. Wskazano na różnice w identyfikacji obiektów wklęsłych jak na przykład typu kite i wypukłych (okrąg). Skoncentrowano uwagę czytelnika na konwencjonalnej metodzie elementów brzegowych z oszczędną dyskretyzacją oraz ilością czujników pomiarowych co ma istotne znaczenia dla zagadnień odwrotnych.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 9.

Tytuł:: Features of light scattering by surface fractal structures
Autorzy:: Semchuk, O.
Grechko, L.
Vodopianov, D.
Kunitska, L.
Tematy:: fractal
scattering
light
electromagnetic wave
scattering coefficient
rough surface; Pokaż więcej
Wydawca:: Politechnika Gdańska
Powiązania:: https://bibliotekanauki.pl/articles/1964137.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 10.

Tytuł:: What can we learn about laser-induced plasmas from Thomson scattering experiments
Autorzy:: Pokrzywka, Bartłomiej
Mendys, Agata
Dzierżęga, Krzysztof
Opis:: This article describes laser Thomson scattering as applied to investigate laser-induced plasmas originating from gas breakdown or ablation of solid samples. Thomson scattering provides a reliable and direct mean of determining plasma electron density and electron temperature with high spatial and temporal resolution. Moreover, unlike e.g. optical emission spectroscopy, no assumptions about axial symmetry, thermodynamic conditions in the plasma or its chemical composition are needed to quantify these fundamental plasma parameters. Because Thomson scattering is inherently accompanied by Rayleigh light scattering, information about concentration of heavy particles and their temperature can be simultaneously derived from the experimental data. The heavy particle temperature and the electron one are the primary indicators of the plasma thermodynamic equilibrium. The goals of this article are to describe the theory of Thomson scattering relevant for the studies of low-temperature laser-induced plasmas, discuss the instrumental details of Thomson scattering experiments, and review the results of studies in which this technique has been used to characterize laser-induced plasmas.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

Artykuł

na półce

Informacja

Wyszukujesz frazę "wave scattering" wg kryterium: Temat