Scattering relations for point-source excitation in chiral media

2005 ◽  
Vol 29 (1) ◽  
pp. 27-48 ◽  
Author(s):  
Christodoulos Athanasiadis ◽  
Nikolaos Berketis
Geophysics ◽  
1996 ◽  
Vol 61 (1) ◽  
pp. 282-287
Author(s):  
Philip Carrion ◽  
José Carcione ◽  
Edson E. S. Sampaio

Recent field measurements of the radiation in boreholes indicate that the radiation patterns of real seismic sources are not always in agreement with those corresponding to the point‐source excitation in unbounded homogeneous and isotropic acoustic or elastic media [we refer the reader to Aki and Richards (1980) for the basic discussion on the radiation patterns in homogeneous media]. This mismatch results from the fact that the point‐source radiation patterns corresponding to homogeneous media are too simplistic to satisfy any experiment in the more realistic Earth environment. A study of radiation patterns is certainly important not only to predict possible seismic events but also to analyze the source performance itself by recording seismic arrivals.


Author(s):  
Amir Darabi ◽  
Michael Leamy

This paper introduces an analytical framework for predicting wave energy harvested by a circular piezoelectric layer from a harmonic point source excitation. The explored acoustic system analyzes a circular piezoelectric disk attached to an infinite host domain. An harmonic point source is located away from the piezoelectric disk on the infinite host layer. The analysis approach decomposes the system into two subdomains, the piezoelectric disk and an infinite plate, which are then separately analyzed. In contrast to traditional analysis methods for such systems (a sandwich of layers with different dimensions), this technique uses internal interaction forces between the different subdomains to find a close-form solution for the vibration of propagating waves over the entire field. In addition, the voltage generated by the harvester is calculated by using coupled electromechanical equations. The analysis is validated by comparing response quantities and frequency response functions at different points on the piezoelectric circular layer and host layers to those predicted using COMSOL simulations, which document good agreement. Analysis of this system is an important stepping stone to the next goal, which is optimization of energy captured from the propagating wave by designing boundary walls (reflector) on the host layer which focus the energy of the wave onto the piezoelectric domain. This focused energy can then be transferred to the electrical power by via a piezoelectric layer through an electrical circuit.


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