Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

English (EN)·Polski (PL)·Yкраїнський (UK)
Przejdź do strony domowej biblioteki Centralna Biblioteka Wojskowa Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaCentralna Biblioteka Wojskowa

Wyszukujesz frazę "Waves" wg kryterium: Temat

  Lista filtrów
Wyrównaj
Wyświetlanie 1-15 z 18
Tytuł:
Numerical simulations of sound wave generation in a random medium
Autorzy:
Murawski, K.
Selwa, M.
Powiązania:
https://bibliotekanauki.pl/articles/1955700.pdf
Data publikacji:
2004
Wydawca:
Politechnika Gdańska
Tematy:
sound waves
random waves
frequency shift
amplitude alteration
Opis:
In turbulent media, both sound wave sources and the speed of sound can be stochastic variables. By means of numerical simulations of one-dimensional Euler equations with random source terms we have studied two cases in a homogeneous stochastic random medium for which the speed of sound and sound sources are: (1) correlated and (2) uncorrelated. The numerical simulations indicate that, if the source and the speed of sound fluctuations are uncorrelated, the acoustic field is incoherent, with a zero expectation value. The mean field is non-zero in the correlated case. The correlated and uncorrelated cases are clearly distinguishable by the mean field, but also - to some extent - in the power spectrum, which displays a modified Lorentzian profile with a shift in frequency.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2004, 8, 1; 109-114
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sound waves in a wave noise
Autorzy:
Murawski, K.
Tarnowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1955702.pdf
Data publikacji:
2004
Wydawca:
Politechnika Gdańska
Tematy:
sound waves
random waves
frequency shift
amplitude alteration
Opis:
We examine by analytical and numerical means sound waves which propagate in a space- and time-dependent random mass density field in the form of dispersionless wave noise of its spectrum E(kappa,omega) ~ E(kappa) delta (omega-crk), where cr is a random speed. Numerical simulations are in agreement with the analytical theory which shows that at cr=omega/k resonance occurs and the cyclic frequency omega tends to infinity. For values of cr which are close to the resonance point, the sound waves are slowed down and attenuated (accelerated and amplified) for cr < omega/k (cr > omega/k).
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2004, 8, 1; 103-108
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
General dynamic projecting of Maxwell equations
Autorzy:
Wojda, P.
Leble, S.
Powiązania:
https://bibliotekanauki.pl/articles/1940709.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska
Tematy:
general electrodynamics
electromagnetic waves
dynamic projecting operators
hybrid waves
parabolic equation
Opis:
A complete – system of Maxwell equations is splitting into independent subsystems by means of a special dynamic projecting technique. The technique relies upon a direct link between field components that determine correspondent subspaces. The explicit form of links and corresponding subspace evolution equations are obtained in conditions of certain symmetry, it is illustrated by examples of spherical and quasi-one-dimensional waves.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2017, 21, 2; 85-96
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Flow simulation at shock wave triple point
Autorzy:
Doerffer, P.
Namieśnik, K.
Magagnato, F.
Powiązania:
https://bibliotekanauki.pl/articles/1967643.pdf
Data publikacji:
2001
Wydawca:
Politechnika Gdańska
Tematy:
transonic flow
shock waves
lambda-foot
Opis:
The paper presents supersonic flow simulation results concerning the lambda-foot formation in the divergent nozzle. The SPARC code was used and the vicinity of the triple point was analysed. Special boundary conditions have been used in order to obtain supersonic inlet velocity with shock wave in the divergent nozzle. It was proved that the condition of pressure equality on both sides of shear layer following the triple point for flow parameter of interest, does not hold.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2001, 5, 4; 549-556
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulation of shock wave patterns in supersonic divergent symmetric nozzles
Autorzy:
Namieśnik, K.
Doerffer, P.
Powiązania:
https://bibliotekanauki.pl/articles/1965149.pdf
Data publikacji:
2005
Wydawca:
Politechnika Gdańska
Tematy:
supersonic flows
supersonic nozzle
shock waves
Opis:
This paper presents the results of numerical simulations of supersonic flows with shock waves in a divergent symmetric nozzle of an opening angle ranging from 2 degrees to 6 degrees. At certain Mach number values the shock pattern becomes asymmetric. This asymmetry is analysed here for different values of velocity upstream of the shock wave and for different nozzle divergence angles. Only the divergent part of the nozzle is considered. Supersonic conditions at the nozzle inlet were prescribed with a chosen Mach number value Ma>1. The inlet velocity profile included a turbulent boundary layer profile on side walls. The steady flow simulation was applied for nozzle opening angles, α , of 1.877 degrees, 2.5 degrees and 3 degrees, whereas the unsteady approach was necessary for a nozzle of the divergence angle α =6.54 degrees to obtain a converged solution. The asymmetry of the shock structure is visible in the unevenness of the heights of both λ-feet. It happens at the same Mach number, at the same boundary layer and with the same geometrical constraints. This is in contradiction with our current understanding of the parameters affecting λ-foot size. The paper provides an explanation of this problem.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2005, 9, 1; 53-63
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interaction of orthogonal-polarized waves in 1D metamaterial with kerr nonlinearity
Autorzy:
Ampilogov, D.
Powiązania:
https://bibliotekanauki.pl/articles/1940704.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska
Tematy:
metamaterials
wave interaction
orthogonal polarized waves
Opis:
The investigation of the wave propagation in a 1D metamaterial is continued in this paper. A nonlinear evolution equation of the wave interaction of two polarizations by means of the projection operator method is obtained and a particular solution in the case of slow-varying envelopes is found.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2017, 21, 2; 149-163
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of wave-noise on wave speeds and amplitudes of surface-gravity waves
Autorzy:
Murawski, K.
Zawada, A.
Powiązania:
https://bibliotekanauki.pl/articles/1954094.pdf
Data publikacji:
2004
Wydawca:
Politechnika Gdańska
Tematy:
random waves
dispersion relation
wave-noise
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.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2004, 8, 3; 321-326
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unsteady Shock Wave: Turbulent boundary layer interaction in the Laval Nozzle
Autorzy:
Doerffer, P.
Szulc, O.
Magagnato, F.
Powiązania:
https://bibliotekanauki.pl/articles/1965143.pdf
Data publikacji:
2005
Wydawca:
Politechnika Gdańska
Tematy:
unsteady transonic flow
shock waves
nozzle flow
Opis:
The flow in transonic diffusers and supersonic air intakes often becomes unsteady due to shock wave-boundary layer interaction. Oscillations may be induced by natural separation unsteadiness or forced by boundary conditions. Significant improvements of CFD tools, increased computer resources and the development of experimental methods have again drawn the attention of researchers to this topic. Forced oscillations of a transonic turbulent flow in an asymmetric two-dimensional Laval nozzle have been considered to investigate the problem. A viscous, perfect gas flow was numerically simulated using SPARC, a Reynolds-averaged compressible Navier-Stokes solver, employing a two-equation, eddy viscosity, turbulence closure in the URANS approach. For time-dependent and stationary flow simulations, Mach numbers upstream of the shock between 1.2 and 1.4 were considered. Comparison of computed and experimental data for steady states generally gave acceptable agreement. In the case of forced oscillations, a harmonic pressure variation was prescribed at the exit plane resulting in shock wave motion. Excitation frequencies between 0Hz and 1024Hz were investigated at a constant pressure amplitude. The main result of the work is the relation between the amplitude of shock wave motion and the excitation frequency in the investigated range. Increasing excitation frequency resulted in decreasing amplitude of the shock movement. At high frequencies, a natural mode of shock oscillation (of small amplitude) was observed, which was insensitive to forced excitement.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2005, 9, 1; 115-132
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamics of wheel-tyre subjected to moving oscillating force
Autorzy:
Bogacz, R.
Kocjan, M.
Kurnik, W.
Powiązania:
https://bibliotekanauki.pl/articles/1986961.pdf
Data publikacji:
2002
Wydawca:
Politechnika Gdańska
Tematy:
railway vehicles
waves
oscillating force
railway wheels
Opis:
The subject of the paper is analysis of wheel of a moving railway vehicle which is subjected to a moving oscillating force. Rail ring is treated as a beam of small curvature connected to wheel axle with a Winkler foundation. Bernoulli-Euler and Timoshenko beam model is used. Results are gained using Fourier transformation. Space and space-time graphs, showing wave propagation in subcritical and supercritical zones of excitation, concerning resonance of transverse vibrations, are included.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 3; 343-350
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tsunami-driven plane acoustic waves in the atmosphere
Autorzy:
Leble, Sergey
Smirnona, Ekaterina
Powiązania:
https://bibliotekanauki.pl/articles/1955273.pdf
Data publikacji:
2018
Wydawca:
Politechnika Gdańska
Tematy:
analytical-numeric modeling
atmosphere waves
tsunami
ionosphere effect
Opis:
A problem of analytical-numerical modeling of the plane wave propagation from an ocean surface to the atmosphere is considered. We are interested in the thermosphere impact of tsunami waves. We suppose that the transport of energy and the momentum from lower atmosphere to thermosphere heights is due to acoustic waves.A set of expressions for the atmosphere variables (pressure, velocity, entropy) as a function of the atmosphere parameters, time and height is derived and illustrated by plots. The surface water wave parameters, typical for tsunami also enter final expressions for the atmosphere and ionosphere variables.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2018, 22, 3; 237--253
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kinetic-induced moment systems for the Saint-Venant equations
Autorzy:
Gil Montoya, D. C.
Struckmeier, J.
Powiązania:
https://bibliotekanauki.pl/articles/1933941.pdf
Data publikacji:
2013
Wydawca:
Politechnika Gdańska
Tematy:
Saint-Venant equations
shallow water equations
Boltzmann equation
hyperbolic conservation laws
kinetic models
kinetic representations
relaxion systems
shock waves
rarefaction waves
Opis:
Based on the relation between kinetic Boltzmann-like transport equations and nonlinear hyperbolic conservation laws, we derive kinetic-induced moment systems for the spatially one-dimensional shallow water equations (the Saint-Venant equations). Using Chapman-Enskog-like asymptotic expansion techniques in terms of the relaxation parameter of the kinetic equation, the resulting moment systems are asymptotically closed without the need for an additional closure relation. Moreover, the new second order moment equation for the (asymptotically) third order system may act as a monitoring function to detect shock and rarefaction waves, which we confirm by a number of numerical experiments.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2013, 17, 1-2; 63-90
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
General equation for directed electromagnetic wave propagation in 1D metamaterial: projecting operator method
Autorzy:
Ampilogov, D.
Leble, S.
Powiązania:
https://bibliotekanauki.pl/articles/1938596.pdf
Data publikacji:
2016
Wydawca:
Politechnika Gdańska
Tematy:
metamaterials
directed waves interactions
Drude dispersion
Kerr nonlinearity
solitary solutions
Opis:
We consider a boundary regime problem for 1D wave propagation in a metamaterial medium with simultaneously negative dielectric permittivity and magnetic permeability. We apply a projecting operator method to the Maxwell system in the time domain that allows the space of the linear propagation problem to be split into subspaces of directed waves for the relations of a given material with general dispersion. After projection, the equations for directed waves have a maximally simplified form, which is most convenient for numerical and analytical integration. Matrix elements of the projectors act as integral operators. For a given nonlinearity and dispersion we derive a general system of interacting right/left waves with combined (hybrid) amplitudes. The result is specified for the Drude metamaterial model for both permittivity and permeability coefficients and the Kerr nonlinearity. We also discuss and investigate singular solitary wave solutions of the system as a limit stationary elliptic system related to some boundary regimes.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2016, 20, 2; 143-155
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effects of lean and sweep on transonic fan performance a computational study
Autorzy:
Denton, J. D.
Powiązania:
https://bibliotekanauki.pl/articles/1986819.pdf
Data publikacji:
2002
Wydawca:
Politechnika Gdańska
Tematy:
transonic fan
transonic compressor
three-dimensional flow
shock waves
CFD
Opis:
The aerodynamics of transonic fans is discussed with emphasis on the use of three-dimensional design techniques, such as blade sweep and lean, to improve their performance. In order to study the interaction of these 3D features with the shock pattern a series of five different designs is produced and analysed by CFD. It is found that the 3D features have remarkably little effect on the shock pattern near the tip where the shock must remain perpendicular to the casing. Lower down the blade significant shock sweep, and hence reduced shock loss, can be induced by 3D design but this is usually at the expense of reduced stall margin and increased loss elsewhere along the blade span. Overall, very little change in efficiency is produced by blade sweep or lean. However, forwards lean of the rotor does produce a small increase in mass flow. Radial migration of the boundary fluid on the suction surface behind the shock is shown to play a large part in the aerodynamics near the blade tip.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 1; 7-23
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On reflection and refraction of plane electromagnetic waves at a conducting matter surface
Autorzy:
Leble, S.
Vereshchagina, S.
Powiązania:
https://bibliotekanauki.pl/articles/1938591.pdf
Data publikacji:
2016
Wydawca:
Politechnika Gdańska
Tematy:
electromagnetic waves
conducting medium
reflection
refraction
Fresnel formula
X-rays refraction
PACS
Opis:
A general problem of monochrome plane electromagnetic wave reflection and refraction at the interface between the conducting medium and the dielectric is formulated and solved by symbolic computation for given incident wave polarization. The conductivity account via the Ohm law directly in the Maxwell equation leads to a complex wavenumber and hence complex amplitudes of the reflected and refracted waves. Atomic absorption is taken into account via the imaginary part of permittivity. The general formula for the time-averaged Pointing vector in the conducting media as a function of the medium parameters and the incident angle is derived and used for the refraction angle definition. The result is compared with textbooks and recent publications. The dependence of intensity as a function of the angle to the interface is determined also via the Pointing vector as a function of the incident wave and medium parameters.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2016, 20, 2; 207-217
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On problem of Rossby and Pointcare atmospheric waves separation and spectra
Autorzy:
Karpov, I.
Leble, S.
Powiązania:
https://bibliotekanauki.pl/articles/1940708.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska
Tematy:
geophysical hydrodynamics
Rossby and Poincare waves
projecting operators
inverse problem
regularization
PACS
Opis:
We propose a new inverse problem formulation based on the hydrodynamics consideration of a gas/water fluid that results in planetary waves diagnostics. We analyze such a possibility beginning from a simplest version of geophysical hydrodynamics, written in the b-plane model. The problem of diagnostics is solved approximately after expansion with respect to the transverse basis functions applying projecting to Rossby and Poincare waves in each transverse subspace that contains its superposition. The corresponding discrete version of the operators is built to be applied to the observation data.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2017, 21, 2; 97-108
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 18

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies