scholarly journals Wave reflection and transmission by an open-bottom airtight chamber for an active wave control system.

1986 ◽  
pp. 271-280
Author(s):  
Tetsushi KIYOKAWA ◽  
Takumi OHYAMA
Keyword(s):  
Control System ◽  
Wave Reflection ◽  
Reflection And Transmission ◽  
Active Wave ◽  
Airtight Chamber ◽  
Wave Control

Wave Propagation Analysis of an Axially Strained, Rotating Timoshenko Shaft: Part II

1997 ◽  
Author(s):  
Bongsu Kang ◽  
Chin An Tan
Keyword(s):  
Boundary Conditions ◽  
Wave Reflection ◽  
Axial Strain ◽  
Free Vibration Analysis ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Propagation Analysis ◽  
Geometric Discontinuities ◽  
Bernoulli Models ◽  
Incident Waves

Abstract In this paper, the wave reflection and transmission characteristics of an axially strained, rotating Timoshenko shaft under general support and boundary conditions, and with geometric discontinuities are examined. As a continuation to Part I of this paper (Kang and Tan, 1997), the wave reflection and transmission at point supports with finite translational and rotational constraints are further discussed. The reflection and transmission matrices for incident waves upon general supports and geometric discontinuities are derived. These matrices are combined, with the aid of the transfer matrix method, to provide a concise and systematic approach for the free vibration analysis of multi-span rotating shafts with general boundary conditions. Results on the wave reflection and transmission coefficients are presented for both the Timoshenko and the Euler-Bernoulli models to investigate the effects of the axial strain, shaft rotation speed, shear and rotary inertia.

THE REFLECTION, REFRACTION, AND DIFFRACTION OF WAVES IN MEDIA WITH AN ELLIPTICAL VELOCITY DEPENDENCE

Geophysics ◽  
1978 ◽  
Vol 43 (3) ◽  
pp. 528-537 ◽  
Author(s):  
Franklyn K. Levin
Keyword(s):  
Wave Reflection ◽  
Transversely Isotropic ◽  
Velocity Dependence ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Transversely Isotropic Media ◽  
Surface Data ◽  
Isotropic Media ◽  
Surface Measurements ◽  
Time Distance

Assuming media having a velocity dependence on angle which is an ellipse, we have confirmed previously reported time‐distance relations for reflections from single interfaces, for reflections from sections of beds separated by horizontal interfaces, for refraction arrivals, and added the expression for diffractions. We also have derived expressions for plane‐wave reflection and transmission coefficients at an interface separating two transversely isotropic media. None of the properties differs greatly from those for isotropic media. However, velocities found from seismic surface reflections or refractions are horizontal components. There seems to be no way of obtaining vertical components of velocity from surface measurements alone and hence no way to compute depths from surface data.

scholarly journals Reflection and Transmission of Acoustic Waves through the Layer of Multifractional Bubbly Liquid

2018 ◽  
Vol 148 ◽  
pp. 15001
Author(s):  
Damir Anvarovich Gubaidullin ◽  
Ramil Nakipovich Gafiyatov
Keyword(s):  
Acoustic Waves ◽  
Wave Reflection ◽  
Water Model ◽  
Bubbly Liquid ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Multilayer Medium ◽  
Bubble Layer ◽  
The Mathematical Model ◽  
Theoretical Results

The mathematical model that determines reflection and transmission of acoustic wave through a medium containing multifractioanl bubbly liquid is presented. For the water-water with bubbles-water model the wave reflection and transmission coefficients are calculated. The influence of the bubble layer thickness on the investigated coefficients is shown. The theory compared with the experiment. It is shown that the theoretical results describe and explain well the available experimental data. It is revealed that the special dispersion and dissipative properties of the layer of bubbly liquid can significantly influence on the reflection and transmission of acoustic waves in multilayer medium

Numerical Simulation of Water Wave Propagation Over Porous Slope Bottom by Using Two-Domain Method

2019 ◽  
Author(s):  
Eun-Hong Min ◽  
Weoncheol Koo
Keyword(s):  
Wave Reflection ◽  
Computational Domain ◽  
Numerical Wave Tank ◽  
Flow Conditions ◽  
Reflection And Transmission ◽  
Wave Characteristics ◽  
Boundary Interaction ◽  
Domain Method ◽  
Propagating Waves ◽  
Numerical Wave

Abstract This study aims at the numerical analysis of wave characteristics when a wave propagates on the porous slope seabed. Numerical wave tank technique was developed using boundary element method with constant panels on the boundary. The fluid was satisfied with potential flow conditions and Darcy’s law was applied for porous intersection. Two computational domain method, which consists of fluid and porous domains, was used to simulate the propagating waves over a sloped seabed having a permeability. To consider fluid-porous boundary interaction, three-step boundary value problems were calculated. The wave amplitude decreased along the free surface as the wave propagated over a sloped bottom. The wave reflection and transmission by subsea structures were also analyzed.

Hybrid Active Wave/Mode Control of Space Prestressed Taut Cable Net Structures

2018 ◽  
Vol 10 (06) ◽  
pp. 1850062 ◽  
Author(s):  
Xiao-Fei Ma ◽  
Tuan-Jie Li ◽  
Zuo-Wei Wang
Keyword(s):  
Shape Control ◽  
Large Scale ◽  
Control Method ◽  
Wave Mode ◽  
Control Model ◽  
Force Balance ◽  
Control Force ◽  
Mode Control ◽  
Active Wave ◽  
Wave Control

The space environments and special mission demands require large-scale and high shape accuracy cable net structures. The vibration control is an essential issue for shape control and performance conservation of large flexible cable net structures. This paper investigates the hybrid active wave/mode control of space prestressed taut cable net structures. First, the traveling wave dynamic model of cable net structures is explored by elemental waveguide and propagation equations of cables together with force balance conditions and compatibility conditions of joints. Then, the active wave control model is established by using the assumption forms of wave controllers to adjust the mechanical boundaries of the controlled joints. Finally, the hybrid active wave/mode control model is proposed by constructing the mapping relationship between wave control force, modal damping and natural frequencies. The proposed control method is verified by a planar cable net structure and the results show that the hybrid active wave/mode control can give a better broadband vibration attenuation performance for space prestressed taut cable net structures.

scholarly journals On Internal Waves Propagating across a Geostrophic Front

2019 ◽  
Vol 49 (5) ◽  
pp. 1229-1248 ◽  
Author(s):  
Qiang Li ◽  
Xianzhong Mao ◽  
John Huthnance ◽  
Shuqun Cai ◽  
Samuel Kelly
Keyword(s):  
Internal Wave ◽  
Internal Waves ◽  
Wave Reflection ◽  
Wave Theory ◽  
Horizontal Shear ◽  
Mixing Rate ◽  
Reflection And Transmission ◽  
Topographic Slope ◽  
Virtual Boundary ◽  
The Impact

AbstractReflection and transmission of normally incident internal waves propagating across a geostrophic front, like the Kuroshio or Gulf Stream, are investigated using a modified linear internal wave equation. A transformation from depth to buoyancy coordinates converts the equation to a canonical partial differential equation, sharing properties with conventional internal wave theory in the absence of a front. The equation type is determined by a parameter Δ, which is a function of horizontal and vertical gradients of buoyancy, the intrinsic frequency of the wave, and the effective inertial frequency, which incorporates the horizontal shear of background geostrophic flow. In the Northern Hemisphere, positive vorticity of the front may produce Δ ≤ 0, that is, a “forbidden zone,” in which wave solutions are not permitted. Thus, Δ = 0 is a virtual boundary that causes wave reflection and refraction, although waves may tunnel through forbidden zones that are weak or narrow. The slope of the surface and bottom boundaries in buoyancy coordinates (or the slope of the virtual boundary if a forbidden zone is present) determine wave reflection and transmission. The reflection coefficient for normally incident internal waves depends on rotation, isopycnal slope, topographic slope, and incident mode number. The scattering rate to high vertical modes allows a bulk estimate of the mixing rate, although the impact of internal wave-driven mixing on the geostrophic front is neglected.

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