Temat: dispersion relation

Skocz do pozycji: 1.

Tytuł:: The influence of wave-noise on wave speeds and amplitudes of surface-gravity waves
Autorzy:: Murawski, K.
Zawada, A.
Tematy:: random waves
dispersion relation
wave-noise; Pokaż więcej
Wydawca:: Politechnika Gdańska
Powiązania:: https://bibliotekanauki.pl/articles/1954094.pdf Link otwiera się w nowym oknie
Opis:: We have analytically examined surface-gravity waves which propagate in space- and time-dependent random velocity fields. Using a perturbative method, we have derived a dispersion relation which is solved for the case of wave-noise whose spectrum E(k,omega) ~ E(k)delta(omega-crk), where delta is Dirac's delta-function and cr is the random phase speed. We have found that for a dispersionless noise resonance occurs when cr is equal to the group velocity cg of the surface-gravity wave. In this resonance the real part of the wave frequency is finite, but its imaginary part exhibits the characteristic 1/x singularity. The wave-noise interacts with a packet of the surface-gravity waves in such a way that the waves are attenuated for cr < cg and are amplified for cr > cg. As the real part is positive for high values of k, the surface-gravity waves are accelerated by the wave-noise.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: The properties of coupled waves propagating in long suspended cables
Własności sprzężonych fal rozprzestrzeniających się w linach o znacznej długości
Autorzy:: Snamina, J.
Tematy:: long cables
coupled waves
dispersion relation
cut-off frequencies; Pokaż więcej
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Powiązania:: https://bibliotekanauki.pl/articles/280708.pdf Link otwiera się w nowym oknie
Opis:: In this paper, the properties of coupled waves travelling along a long cable are analysed. Since the tension and curvature in the equilibrium position of the cable are slowly varying functions of the arc co-ordinate, the problems concerning the travelling waves can be solved using the Wentzel-Kramers-Brillouin (WKB) method. The waves propagating in the plane of the equilibrium curve are coupled. The wave associated with displacements perpendicular to the plane is uncoupled from the remaining waves. Applying the WKB method, the dispersion relation and equations describing the amplitudes of waves are determined. For a longitudinal-dominated pair of waves, there exist two cut-off frequencies depending on the arc co-ordinate. The results of calculations of wavelengths and amplitudes are presented in the form of plots.
W pracy przedstawiono analizę własności fal mechanicznych rozprzestrzeniających się w linach o znacznej długości. W liniowej teorii fale rozchodzące się w płaszczyźnie zwisu są ze sobą sprzężone, a fala wywołująca przemieszczenia punktów liny w kierunku prostopadłym do płaszczyzny zwisu rozprzestrzenia się niezależnie od pozostałych fal. W rozważaniach uwzględniono wolno-zmienną zależność siły osiowej i krzywizny od współrzędnej łukowej, w położeniu równowagi statycznej liny. Zagadnienia dotyczące przemieszczających się wzdłuż przewodu fal rozwiązano metodą WKB (Wentzel-Kramers-Brillouin).Wyznaczono związki dyspersyjne charakteryzujące ruch falowy w linach, wyprowadzono prędkości fazowe i grupowe z uwzględnieniem sprzężenia fal rozchodzących się w płaszczyźnie zwisu. Analizie poddano zależność liczb falowych oraz amplitud od współrzędnej łukowej. W rozważaniach wykorzystano symetrię ruchu fal. Wyniki obliczeń zostały zobrazowane na szeregu wykresach.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Surface plasmon polariton dispersion relation at organic/dielectric/metal interfaces
Autorzy:: Kawalec, Tomasz
Józefowski, Leszek
Fiutowski, Jacek
Bordo, Vladimir
Kostiučenko, Oksana
Rubahn, Horst-Günter
Opis:: The dispersion relation of a hybrid photonic–plasmonic system consisting of a light emitting thin organic para-Hexaphenylene (p-6P) layer separated by a dielectric gap from a plasmonic silver film is investigated using leakage radiation spectroscopy. Experimental studies are complemented by numerical simulations for the same structure but in the complementary, inverted configuration. The numerical simulations use as input ellipsometric measurements providing optical constants of p-6P in a wide spectral range. From a comparison between calculated and measured dispersion curves it is concluded that the molecular excitons in the p-6P film, created in the course of ultraviolet illumination of the sample, are de-excited via excitation of a plasmonic mode of the metal film.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 4.

Tytuł:: Anisotropic plasma at strong coupling and R-charge fluctuations
Autorzy:: Witaszczyk, Przemysław
Opis:: We briefly discuss our first attempt to describe an anisotropic quark-gluon plasma at strong coupling in the AdS/CFT correspondence framework. We constructed an exact dual gravity solution and found that despite the fact that it is singular it allows for a construction of natural incoming boundary conditions. A study of a small perturbation about this geometry shows that the dispersion relation depends strongly on the relative sign of the wave vector and the sign of the anisotropy. Yet, we did not encounter any instabilities.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 5.

Tytuł:: Extended elliptic mild slope equation incorporating the nonlinear shoaling effect
Autorzy:: Xiao, Q. L.
Li, Ch. H.
Fu, X. Y.
Wang, M. J.
Tematy:: nonlinear dispersion relation
nonlinear shoaling coefficient
extended elliptic mild slope equation
surf zone
wave transformation; Pokaż więcej
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Powiązania:: https://bibliotekanauki.pl/articles/258718.pdf Link otwiera się w nowym oknie
Opis:: The transformation during wave propagation is significantly important for the calculations of hydraulic and coastal engineering, as well as the sediment transport. The exact wave height deformation calculation on the coasts is essential to near-shore hydrodynamics research and the structure design of coastal engineering. According to the wave shoaling results gained from the elliptical cosine wave theory, the nonlinear wave dispersion relation is adopted to develop the expression of the corresponding nonlinear wave shoaling coefficient. Based on the extended elliptic mild slope equation, an efficient wave numerical model is presented in this paper for predicting wave deformation across the complex topography and the surf zone, incorporating the nonlinear wave dispersion relation, the nonlinear wave shoaling coefficient and other energy dissipation factors. Especially, the phenomenon of wave recovery and second breaking could be shown by the present model. The classical Berkhoff single elliptic topography wave tests, the sinusoidal varying topography experiment, and complex composite slopes wave flume experiments are applied to verify the accuracy of the calculation of wave heights. Compared with experimental data, good agreements are found upon single elliptical topography and one-dimensional beach profiles, including uniform slope and step-type profiles. The results indicate that the newly-developed nonlinear wave shoaling coefficient improves the calculated accuracy of wave transformation in the surf zone efficiently, and the wave breaking is the key factor affecting the wave characteristics and need to be considered in the nearshore wave simulations.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Estimation of acoustically induced refractive index perturbation in silicon and germanium slab for optical applications
Autorzy:: Sharma, G.
Kumar, S.
Kumar, D.
Singh, V.
Tematy:: dispersion relation
Lamb wave mode in silicon and germanium
displacement field
refractive index modulation; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/173371.pdf Link otwiera się w nowym oknie
Opis:: In-plane displacement field and refractive index variation for silicon and germanium in the presence of Lamb wave is estimated for optical applications. The required dispersion equation in a thin silicon and germanium plates is obtained using the method of potentials with boundary conditions involving the bulk and surface stress of the materials considered. The eigen-values thus obtained are used to compute the Lamb wave modes for the slab of silicon and germanium at same thickness. The fundamental anti-symmetric and symmetric plate modes and their overtones are observed due to confinement of acoustic energy within the slab thickness. In addition, the excited symmetric modes in silicon have longer wavelengths than those of germanium at a fixed frequency. Therefore, the refractive index modulation through the Lamb wave in silicon is always larger as compared to that of germanium. This refractive index modulation can be treated as periodic sinusoidal refractive index variation and may be considered as a tunable one-dimensional photonics crystal.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Properties of low frequency TE-electromagnetic wave in ternary plasma photonic crystal
Autorzy:: Dehnavi, Z. N.
Askari, H. R.
Malekshahi, M.
Dorranian, D.
Tematy:: plasma photonic crystal
effective plasma frequency
photonic band gap
dispersion relation
group velocity
reflectivity; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/174815.pdf Link otwiera się w nowym oknie
Opis:: In this study, the oblique incident of the electromagnetic waves with frequencies lower than plasma frequency in one dimensional ternary plasma photonic crystal has been investigated. The unit cell of crystal contains a plasma layer that is embedded in two different dielectric layers. Using the wave equation, Bloch theory, and boundary condition, the dispersion relation, the group velocity and the reflection relation of the structure have been obtained. Numerical results are presented in the form of dispersion curves. The dependence of photonic band gap characteristics on plasma frequency is discussed. One attempt has been made to show how the photonic band gap characteristic of a particular structure changes when the dielectric material of the unit cell is replaced by other dielectric materials or when the incident angle of the electromagnetic wave is changed. Results show that plasma layer characteristics has a significant effect on band gaps and wave propagation characteristics; also the results show that the proposed multi-layered structure can act as a tunable photonic crystal which can be controlled by the external parameters.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Instability and the formation of bubbles and the plugs in fluidized beds
Autorzy:: Schulz, P.
Tematy:: multiphase flow
bubbling
linear and non linear instability
dispersion relation
periodic plugs (or slugs); Pokaż więcej
Wydawca:: Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Powiązania:: https://bibliotekanauki.pl/articles/2050193.pdf Link otwiera się w nowym oknie
Opis:: This is an review paper, particulary concentrate on results not many researches by reason that are explain in the text. We consider stability of disperse, two-phase flow (gas-solid particles or liquid-solid particles) linear and non-linear. In particular we discuss the result of Anderson, Sundareson and Jackson (1995) [3] that for vertical dispersion flow one- and two-dimensional, they attack problem growing disturbances directly by numerical integration of equations of motion from given initial conditions (using computer Cray C-90). In principle, this would allow authors to explore all aspects of dynamical behaviour of fluidized beds. It is interesting mechanism of periodic plug describing by Anderson et al. and attest by other researchers. Second part of paper is more general, dedicate the problem of linear stability of uniformly fluidized state ("fluidized bed"). We make the most important stages of calculations (after to Jackson (2000) [23]) and demonstrate that the majority (but not all) of fluidized beds with parameters having technical importance is unstable, or stable in narrow interval of wave numbers k.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Edge waves over a shelf
Autorzy:: Dolai, P.
Dolai, D. P.
Tematy:: fala brzegowa
wielomian Gegenbauera
relacja dyspersji
shelf
edge wave
Havelock expansion
Galerkin approximation
Gegenbauer polynomial
dispersion relation; Pokaż więcej
Wydawca:: Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:: https://bibliotekanauki.pl/articles/264611.pdf Link otwiera się w nowym oknie
Opis:: The problem considered in this paper is the derivation of properties of edge waves travelling along a submerged horizontal shelf. The problem is formulated within the framework of the linearized theory of water waves and Havelock expansions of water wave potentials are used in the mathematical analysis to obtain the dispersion relation for edge waves in terms of an integral. Appropriate multi-term Galerkin approximations involving ultra spherical Gegenbauer polynomials are utilized to obtain a very accurate numerical estimate for the integral and hence to derive the properties of edge waves over a shelf. The numerical results are illustrated in a table and curves are presented showing the variation of frequency of the edge waves with the width of the shelf.
Dostawca treści:: Biblioteka Nauki

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