scholarly journals Transient elasticity imaging and time reversal

2011 ◽  
Vol 141 (6) ◽  
pp. 1121-1140 ◽  
Author(s):  
Habib Ammari ◽  
Lili Guadarrama Bustos ◽  
Hyeonbae Kang ◽  
Hyundae Lee
Keyword(s):  
Elastic Wave ◽  
Time Reversal ◽  
Stokes System ◽  
Quantitative Estimation ◽  
Field Measurements ◽  
Geometrical Parameters ◽  
Far Field ◽  
Layer Potential ◽  
Incompressible Elasticity ◽  
Wave Induced

We consider a purely quasi-incompressible elasticity model. We rigorously establish asymptotic expansions of near- and far-field measurements of the transient elastic wave induced by a small elastic anomaly. Our proof uses layer potential techniques for the modified Stokes system. Based on these formulae, we design asymptotic imaging methods leading to a quantitative estimation of elastic and geometrical parameters of the anomaly.

Ultrasonic Imaging of a Crack Using Modified Time Reversal

2016 ◽  
Vol 846 ◽  
pp. 553-558
Author(s):  
Jed Guinto ◽  
Philippe Blanloeuil ◽  
Chun H. Wang ◽  
Francis Rose ◽  
Martin Veidt
Keyword(s):  
Time Reversal ◽  
Computational Simulation ◽  
Field Measurements ◽  
Tone Burst ◽  
Data Matrix ◽  
Accurate Estimation ◽  
Diffraction Tomography ◽  
Static Data ◽  
Reconstruction Quality ◽  
Scatter Field

A majority of the research in Structural Health Monitoring focuses on detection of damage. This paper presents a method of imaging crack damage in an isotropic material using the Time Reversal imaging algorithm. Inputs for the algorithm are obtained via computational simulation of the propagation field of a crack in a medium under tone-burst excitation. The approach is similar to existing techniques such as Diffraction Tomography which makes use of the multi-static data matrix constructed using scatter field measurements from the computational simulation. Results indicate excellent reconstruction quality and accurate estimation of damage size.

Micro Roughness Determination Of Periodic Microelectronics Structures Using Optical Far Field Measurements

2011 ◽  
Author(s):  
Alexandre Vauselle ◽  
Philippe Maillot ◽  
Gaëlle Georges ◽  
Carole Deumié ◽  
David G. Seiler ◽  
...  
Keyword(s):  
Field Measurements ◽  
Far Field

Modal structure from far-field measurements

1988 ◽  
Vol 24 (12) ◽  
pp. 2352-2354 ◽  
Author(s):  
R.T. Hammond
Keyword(s):  
Field Measurements ◽  
Far Field ◽  
Modal Structure

Antenna Far Field Reconstruction by a Minimum Near Field Measurements

1984 ◽  
Author(s):  
G. D'Elia ◽  
G. Leone ◽  
R. Pierri ◽  
G. Schirinzi
Keyword(s):  
Near Field ◽  
Field Measurements ◽  
Far Field ◽  
Field Reconstruction

Mode analysis of gyrotron radiation by far field measurements

1983 ◽  
Author(s):  
Z. X. Zhang ◽  
G. Janzen ◽  
G. Muller ◽  
P. G. Schuller ◽  
M. Thumm ◽  
...  
Keyword(s):  
Field Measurements ◽  
Mode Analysis ◽  
Far Field

scholarly journals Scattering centers modeling of non-anechoic measurement environments

2012 ◽  
Vol 10 ◽  
pp. 69-73 ◽  
Author(s):  
K. A. Yinusa ◽  
C. H. Schmidt ◽  
T. F. Eibert
Keyword(s):  
Near Field ◽  
Field Measurements ◽  
Field Pattern ◽  
Far Field ◽  
Scattering Centers ◽  
Field Transformation ◽  
Field Radiation ◽  
Echo Suppression ◽  
Multipath Signals ◽  
Far Field Pattern

Abstract. Near-field measurements are established techniques to obtain the far-field radiation pattern of an Antenna Under Test via near-field measurements and subsequent near-field far-field transformation. For measurements acquired in echoic environments, additional post-processing is required to eliminate the effects of multipath signals in the resulting far-field pattern. One of such methods models the measurement environment as a multiple source scenario whereby the collected near-field data is attributed to the AUT and some scattering centers in the vicinity of the AUT. In this way, the contributions of the AUT at the probe can be separated from those of the disturbers during the near-field far-field transformation if the disturber locations are known. In this paper, we present ways of modeling the scattering centers on equivalent surfaces such that echo suppression is possible with only partial or no information about the geometry of the scatterers.

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