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Wyszukujesz frazę "wave damping" wg kryterium: Temat

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    Wyświetlanie 1-10 z 10
    Tytuł:
    Modeling of Waves Propagating in Water with a Crushed Ice Layer on the Free Surface
    Autorzy:
    Szmidt, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/241428.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
    Tematy:
    gravitational wave
    crushed ice
    wave damping
    Opis:
    A transformation of gravitational waves in fluid of constant depth with a crushed ice layer floating on the free fluid surface is considered. The propagating waves undergo a slight damping along their path of propagation. The main goal of the study is to construct an approximate descriptive model of this phenomenon.With regard to small displacements of the free surface, a viscous type model of damping is considered, which corresponds to a continuous distribution of dash-pots at the free surface of the fluid. A constant parameter of the dampers is assumed in advance as known parameter of damping. This parameter may be obtained by means of experiments in a laboratory flume.
    Źródło:
    Archives of Hydro-Engineering and Environmental Mechanics; 2017, 64, 2; 87-99
    1231-3726
    Pojawia się w:
    Archives of Hydro-Engineering and Environmental Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of Structural and Non-Structural Disaster Mitigation Due to Erosion in the Timbulsloko Village, Demak – Central Java
    Autorzy:
    Sugianto, Denny Nugroho
    Widiaratih, Rikha
    Widada, Sugeng
    Suripin, -
    Handayani, Elinna Putri
    Cahyaningtyas, Putri
    Powiązania:
    https://bibliotekanauki.pl/articles/2027833.pdf
    Data publikacji:
    2022
    Wydawca:
    Polskie Towarzystwo Inżynierii Ekologicznej
    Tematy:
    wave damping
    permeable breakwater
    coastal erosion
    Timbulsloko Village
    coastal vulnerability analysis
    coastal vulnerability index
    Opis:
    Timbulsloko is a village on the coast of Sayung District, Demak Regency that is severely affected by coastal erosion. The coastal erosion in the Timbulsloko Village is mainly caused by the removal of mangrove areas, which has eliminated the function of the natural breakwater for the coast of the Timbulsloko Village. This study aimed to mitigate the coastal erosion in the form of structural and non-structural protection. Structurally (physically), mitigation is conducted by protecting the coastal area with the application of environmentally friendly coastal protection technology in the form of a Permeable breakwater with a Hybrid Engineering structure. Furthermore, the effectiveness of two different structure segments in damping waves from September 2020 – March 2021 will be measured. In contrast, non-structurally, mitigation is conducted in a non-physical way by analyzing the Coastal Vulnerability Index of Timbulsloko Village based on the parameters of Coastal Typology, Average Tidal Range, Significant Wave Height, Coastal Slope, Coastal Geomorphology, Sea Level Rises, and Shoreline Displacement using the CVI method. The effectiveness of the permeable structure’s wave damping is determined by the initial wave height and transmission wave height measured by the ultrasonic sensor. On the basis of segment differences, the Permeable Breakwater Segment 2 with a distance between bamboo of 0.25 m has better effectiveness than a Permeable Breakwater Segment 1 with a distance between bamboo of 0.5 m. The results of the Coastal Vulnerability Analysis show that the Timbulsloko Village is vulnerable to coastal disasters, especially coastal erosion.
    Źródło:
    Journal of Ecological Engineering; 2022, 23, 2; 246-254
    2299-8993
    Pojawia się w:
    Journal of Ecological Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Detection of wavy sea surface oil-derivative contamination with forward specular high-frequency scattering
    Autorzy:
    Pogorzelski, Stanisław
    Rochowski, Paweł
    Grzegorczyk, Maciej
    Linde, Bogumił B. J.
    Skrodzka, Ewa
    Bielasiewicz, Łukasz
    Powiązania:
    https://bibliotekanauki.pl/articles/260616.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    crude oil contamination
    capillary wave damping
    acoustic surface scattering
    statistical-frequency analyses
    at-sea pollution detection
    Opis:
    A spectrum of low-frequency (20‒30 Hz) amplitude fluctuations of the ultrasonic (10 MHz) signal specularly scattered from water surfaces covered with monomolecular and thicker crude oil origin films of well-defined, oceanographically relevant viscoelastic properties was examined in laboratory and at-sea conditions. The relationship between the Surface water wave (30 Hz) damping coefficient and the oil layer thickness was established, and compared to the one predicted by the classical Stokes theory. The depression of the spectral energy density of wind-driven waves by surface films was inferred from the ratio of acoustic signal fluctuations spectra with/without films, and compared to that resulting from the Marangoni damping theory applicable to monolayers of particular surface viscoelasticity. The agreement between the theory and experimental data was satisfactory. As shown in at-sea experiments performed with a free-floating, buoy-like acoustic system, and an artificial oil slick spread over the Baltic Sea surface, the film’s rheological Surface properties can be recovered from acoustic surface probing, as well as oil spill edge detection. Simultaneous statistical analyses of the scattered signal amplitude distribution parameters turned out to be unequivocally related to the oil substance fraction weight, oil layer thickness, and the form of oil contamination.
    Źródło:
    Polish Maritime Research; 2020, 1; 173-179
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Global well-posedness of a class of fourth-order strongly damped nonlinear wave equations
    Autorzy:
    Yanbing, Yang
    Ahmed, Md Salik
    Lanlan, Qin
    Runzhang, Xu
    Powiązania:
    https://bibliotekanauki.pl/articles/255961.pdf
    Data publikacji:
    2019
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    fourth-order nonlinear wave equation strong damping
    blow up
    global existence
    Opis:
    Global well-posedness and finite time blow up issues for some strongly damped nonlinear wave equation are investigated in the present paper. For subcritical initial energy by employing the concavity method we show a finite time blow up result of the solution. And for critical initial energy we present the global existence, asymptotic behavior and finite time blow up of the solution in the framework of the potential well. Further for supercritical initial energy we give a sufficient condition on the initial data such that the solution blows up in finite time.
    Źródło:
    Opuscula Mathematica; 2019, 39, 2; 297-313
    1232-9274
    2300-6919
    Pojawia się w:
    Opuscula Mathematica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Selfsimilar profiles in large time asymptotics of solutions to damped wave equations
    Autorzy:
    Karch, Grzegorz
    Powiązania:
    https://bibliotekanauki.pl/articles/1205809.pdf
    Data publikacji:
    2000
    Wydawca:
    Polska Akademia Nauk. Instytut Matematyczny PAN
    Tematy:
    generalized wave equation with damping
    the Cauchy problem
    large time behavior of solutions
    selfsimilar solutions
    Opis:
    Large time behavior of solutions to the generalized damped wave equation $u_{tt} +A u_t +ν B u+F(x,t,u,u_t,∇ u) = 0$ for $(x,t)∈ ℝ^n × [0,∞)$ is studied. First, we consider the linear nonhomogeneous equation, i.e. with F = F(x,t) independent of u. We impose conditions on the operators A and B, on F, as well as on the initial data which lead to the selfsimilar large time asymptotics of solutions. Next, this abstract result is applied to the equation where $Au_t = u_t$, $Bu = -Δu$, and the nonlinear term is either $|u_t|^{q-1}u_t$ or $|u|^{α-1}u$. In this case, the asymptotic profile of solutions is given by a multiple of the Gauss-Weierstrass kernel. Our method of proof does not require the smallness assumption on the initial conditions.
    Źródło:
    Studia Mathematica; 2000, 143, 2; 175-197
    0039-3223
    Pojawia się w:
    Studia Mathematica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On the nonlinear stabilization of the wave equation
    Autorzy:
    Guesmia, Aissa
    Powiązania:
    https://bibliotekanauki.pl/articles/1294506.pdf
    Data publikacji:
    1998
    Wydawca:
    Polska Akademia Nauk. Instytut Matematyczny PAN
    Tematy:
    wave equation
    nonlinear damping
    integral inequality
    Opis:
    We obtain a precise decay estimate of the energy of the solutions to the initial boundary value problem for the wave equation with nonlinear internal and boundary feedbacks. We show that a judicious choice of the feedbacks leads to fast energy decay.
    Źródło:
    Annales Polonici Mathematici; 1998, 68, 2; 191-198
    0066-2216
    Pojawia się w:
    Annales Polonici Mathematici
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Stability of higher-level energy norms of strong solutions to a wave equation with localized nonlinear damping and a nonlinear source term
    Autorzy:
    Lasiecka, I.
    Toundykov, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/970252.pdf
    Data publikacji:
    2007
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    wave equation
    localized nonlinear damping
    nonlinear source
    stability
    uniform boundedness
    higher energy
    strong solutions
    Opis:
    We derive global in time a priori bounds on higher-level energy norms of strong solutions to a semilinear wave equation: in particular, we prove that despite the influence of a nonlinear source, the evolution of a smooth initial state is globally bounded in the strong topology ∼ H2 x H1. And the bound is uniform with respect to the corresponding norm of the initial data. It is known that an m-accretive semigroup generator moriotoni-cally propagates smoothness of the initial condition; however, this result does not hold in general for Lipschitz perturbations of monotone systems where higher order Sobolev norms of the solution may blowup asymptotically as t → ∞. Due to nonlinearity of the system, the only a priori global-in-time bound that follows from classical methods is that on finite energy: ∼ H1 x L2. We show that under some correlation between growth rates of the damping and the source, the norms of topological order above the finite energy level remain globally bounded. Moreover, we also establish this result when damping exhibits sublinear or superlinear growth at the origin, or at infinity, which has immediate applications to asymptotic estimates on the decay rates of the finite energy. The approach presented in the paper is not specific to the wave equation, and can be extended to other hyperbolic systems: e.g. plate, Maxwell, and Schrodinger equations.
    Źródło:
    Control and Cybernetics; 2007, 36, 3; 681-710
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Uniform stabilization of the quasi-linear Kirchhoff wave equation with a nonlinear boundary feedback
    Autorzy:
    Lasiecka, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/206039.pdf
    Data publikacji:
    2000
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    quasi-liniowe równanie falowe Kirchhoffa
    a priori bounds
    global existence
    nonlinear damping
    quasilinear Kirchhoff wave equation
    uniform decay rates
    Opis:
    An n-dimensional quasi-linear wave equation defined on bounded domain Omega with Neumann boundary conditions imposed on the boundary Gamma and with a nonlinear boundary feedback acting on a portion of the boundary [Gamma sup 1 is a subset of Gamma] is considered. Global existence, uniqueness and uniform decay rates are established for the model, under the assumption that the H[sup 1](Omega) x L[sub 2](Omega) norms of the initial data are sufficiently small. The result presented in this paper extends these obtained recently in Lasiecka and Ong (1999), where the Dirichlet boundary conditions are imposed on the uncontrolled portion of the boundary Gamma[sub o] = Gamma \ [closure of a set Gamma sub 1], and the two portions of the boundary are assumed disjoint, i.e. [... ]. The goal of this paper is to remove this restriction. This is achieved by considering the "pure" Neumann problem subject to convexity assumption imposed on Gamma[sub o]. \@eng\\
    Źródło:
    Control and Cybernetics; 2000, 29, 1; 179-197
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Existence and uniqueness of solutions to wave equations with nonlinear degenerate damping and source terms
    Autorzy:
    Barbu, V.
    Lasiecka, I.
    Rammaha, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/970548.pdf
    Data publikacji:
    2005
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    równanie falowe
    rozwiązania słabe
    wave equations
    damping and source terms
    weak solutions
    subdifferential
    blow-up of solutions
    energy estimates
    Opis:
    In this article we focus on the global well-posedness of the differential equation u [...] in Omega x(O, T), where j' denotes the derivative of a C1 convex and real valued function j. The interaction between degenerate damping and a source term constitutes the main challenge of the problem. Problems with non-degenerate damping (k = 0) have been studied in the literature (Georgiev and Todorova, 1994; Levine and Serrin, 1997; Vitillaro, 2003). Thus the degeneracy of monotonicity is the main novelty of this work. Depending on the level of interaction between the source and the damping we characterize the domain of the parameters p, m, k, n (see below) for which one obt ains existence, regularity or finite time blow up of solutions. More specifically, when p [is less than or equal to] m + k global existence of generalized solutions in H1 x L2 is proved. For p > m + k, solutions blow up in a finite time. Higher energy solutions are studied as well. For H2 x H1 initial data we obtain both local and global solutions with the same regularity. Higher energy solutions are also proved to be unique.
    Źródło:
    Control and Cybernetics; 2005, 34, 3; 665-687
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ultrasound Wave Attenuation of Grain Refined High – Zinc Aluminium Sand-cast Alloys
    Autorzy:
    Krajewski, W. K.
    Buraś, J.
    Krajewski, P. K.
    Piwowarski, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/379936.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    high zinc Al alloy
    sand casting
    grain refinement
    damping capacity
    attenuation
    ultrasound wave
    strength properties
    stop wysokocynkowy
    stop Al
    odlew piaskowy
    rozdrobnienie ziarna
    tłumienie
    fala ultradźwiękowa
    właściwości wytrzymałościowe
    Opis:
    The paper presents results of measuring attenuation coefficient of the Al-20 wt.% Zn alloy (AlZn20) inoculated with different grain refiners. During experiments the melted alloys were doped with Al-Ti3-C0.15 refining master alloy. Basing on measurements performed by Krautkramer USLT2000 device with 1MHz ultrasound wave frequency it was stated that grain refinement reduces the attenuation coefficient by about 20-25%. However, the examined alloys can be still classified as the high-damping ones of attenuation greater than 150 dB/m.
    Źródło:
    Archives of Foundry Engineering; 2015, 15, 2; 51-54
    1897-3310
    2299-2944
    Pojawia się w:
    Archives of Foundry Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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