scholarly journals WAVE TRANSMISSION THROUGH TRAPEZOIDAL BREAKWATERS

1978 ◽  
Vol 1 (16) ◽  
pp. 129 ◽  
Author(s):  
Ole Secher Madsen ◽  
Paisal Shusang ◽  
Sue Ann Hanson
Keyword(s):  
Energy Dissipation ◽  
Approximate Method ◽  
Cross Section ◽  
Wave Energy ◽  
Graphical Form ◽  
Dissipated Energy ◽  
Simple Method ◽  
Reflection And Transmission ◽  
Transmission Coefficients

In a previous paper Madsen and White (1977) developed an approximate method for the determination of reflection and transmission characteristics of multi-layered, porous rubble-mound breakwaters of trapezoidal cross-section. This approximate method was based on the assumption that the energy dissipation associated with the wave-structure interaction could be considered as two separate mechanisms: (1) an external, frictional dissipation on the seaward slope; (2) an internal dissipation within the porous structure. The external dissipation on the seaward slope was evaluated from the semi-theoretical analysis of energy dissipation on rough, impermeable slopes developed by Madsen and White (1975). The remaining wave energy was represented by an equivalent wave incident on a hydraulically equivalent porous breakwater of rectangular cross-section. The partitioning of the remaining wave energy among reflected, transmitted and internally dissipated energy was evaluated as described by Madsen (1974), leading to a determination of the reflection and transmission coefficients of the structure. The advantage of this previous approximate method was its ease of use. Input data requirements were limited to quantities which would either be known (water depth, wave characteristics, breakwater geometry, and stone sizes) or could be estimated (porosity) by the design engineer. This feature was achieved by the employment of empirical relationships for the parameterization of the external and internal energy dissipation mechanisms. General solutions were presented in graphical form so that calculations could proceed using no more sophisticated equipment than a hand calculator (or a slide rule). This simple method gave estimates of transmission coefficients in excellent agreement with laboratory measurements whereas its ability to predict reflection coefficients left a lot to be desired.

scholarly journals ARPEC: A NOVEL STAGGERED PERFORATED CAISSON FOR WAVE ABSORPTION AND TIDAL FLUSHING

2020 ◽  
pp. 26
Author(s):  
Paolo Sammarco ◽  
Leopoldo Franco ◽  
Giorgio Bellotti ◽  
Claudia Cecioni ◽  
Stefano DeFinis
Keyword(s):  
Energy Dissipation ◽  
Water Flow ◽  
Wave Energy ◽  
Reflection And Transmission ◽  
Wave Energy Dissipation ◽  
Wave Absorption ◽  
Transmission Coefficients ◽  
Open Sea ◽  
Caisson Breakwater ◽  
Perforated Caisson

An innovative caisson breakwater geometry (patent pending) named "ARPEC" (Anti Reflective PErmeable Caisson) includes openings at all external and internal walls and at lateral (cross) ones, yet in a staggered pattern, to provide a labyrinthian hydraulic communication between the open sea and the internal waters. The complex sinuous water-flow within the consecutive permeable chambers thus favors wave energy dissipation as well as port water flushing and quality, with very low reflection and transmission coefficients. 2D lab model tests demonstrate the system effectiveness.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/PaUsinYO-Zo

THE SEISMIC WAVE ENERGY REFLECTED FROM VARIOUS TYPES OF STRATIFIED HORIZONS

Geophysics ◽  
1940 ◽  
Vol 5 (2) ◽  
pp. 149-155 ◽  
Author(s):  
M. Muskat ◽  
M. W. Meres
Keyword(s):  
Seismic Wave ◽  
Wave Energy ◽  
Incident Energy ◽  
Preceding Paper ◽  
Reflection And Transmission Coefficients ◽  
Angle Of Incidence ◽  
Reflection And Transmission ◽  
Transmission Coefficients

Two applications are made of the reflection and transmission coefficients reported in the preceding paper. These concern the effect of the angle of incidence upon the fraction of incident energy returning to the surface, and the effect of velocity stratification upon the energy return.

Thin-Film Optical Constants Determined from Infrared Reflectance and Transmittance Measurements

1989 ◽  
Vol 43 (6) ◽  
pp. 1027-1032 ◽  
Author(s):  
Thierry Buffeteau ◽  
Bernard Desbat
Keyword(s):  
Thin Films ◽  
Optical Constants ◽  
Grazing Incidence ◽  
Infrared Region ◽  
Matrix Formalism ◽  
Experimental Conditions ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Multilayered Systems

A general method based upon reflectance and transmittance measurements in the infrared region has been developed for the determination of the optical constants n( v) and k( v) of thin films deposited on any substrate (transparent or not). The corresponding computer program, written in FORTRAN 77, involves three main parts: (1) a matrix formalism to compute reflection and transmission coefficients of multilayered systems; (2) an iterative Newton-Raphson method to estimate the optical constants by comparison of the calculated and experimental values; and (3) a fast Kramers-Krönig transform to improve the accuracy of calculating the refractive index. The first part of this program can be used independently to simulate reflection and transmission spectra of any multilayered system using various experimental conditions. Two practical examples are given for illustration. Simulation of reflection spectra at grazing incidence for thin films deposited on a metal surface and determination of the optical constants for thin CaF2 layers deposited on a silicon substrate are presented.

scholarly journals Determination of Complex Conductivity of Thin Strips with a Transmission Method

Electronics ◽  
2018 ◽  
Vol 8 (1) ◽  
pp. 21 ◽  
Author(s):  
Morteza Shahpari
Keyword(s):  
Method Of Moments ◽  
Material Properties ◽  
Reflection And Transmission Coefficients ◽  
Complex Conductivity ◽  
Transmission Method ◽  
Reflection And Transmission ◽  
Wave Modelling ◽  
Transmission Coefficients ◽  
Full Wave

Induced modes due to discontinuities inside the waveguide are dependent on the shape and material properties of the discontinuity. Reflection and transmission coefficients provide useful information about material properties of discontinuities inside the waveguide. A novel non-resonant procedure to measure the complex conductivity of narrow strips is proposed in this paper. The sample is placed inside a rectangular waveguide which is excited by its fundamental mode. Reflection and transmission coefficients are calculated by the assistance of the Green’s functions and enforcing the boundary conditions. We show that resistivity only impacts one of the terms in the reflection coefficient. The competency of the method is demonstrated with a comparison of theoretic results and full wave modelling of method of moments and finite element methods.

Propagation of acoustic waves in layered porous media

2007 ◽  
Vol 5 ◽  
pp. 169-175
Author(s):  
V.L. Dmitriev ◽  
Е.А. Ponomareva
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Dispersion Relation ◽  
Acoustic Waves ◽  
Saturated Liquid ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Layered Porous Media ◽  
The Media

The paper considers the processes of reflection and transmission acoustic waves at the interface between two porous media, saturated liquid or gas. The cases of a porous medium whose layers have the same porosity, but are saturated with different fluids. Based The dispersion relation and the conditions at the interface between the media are obtained reflection and transmission coefficients. The possibility determination of the parameters of the porous material and its saturating fluid based on the signal reflected from the interface.

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