scholarly journals Three dimensional complex permittivity reconstruction by means of Newton-type microwave imaging

2006 ◽  
Author(s):  
J. De Zaeytijd ◽  
A. Franchois ◽  
C. Eyraud ◽  
J-M. Geffrin
Keyword(s):  
Complex Permittivity ◽  
Three Dimensional ◽  
Microwave Imaging

Experimental microwave imaging of three-dimensional targets with different inversion procedures

2009 ◽  
Vol 106 (3) ◽  
pp. 034901 ◽  
Author(s):  
P. C. Chaumet ◽  
K. Belkebir ◽  
A. Sentenac
Keyword(s):  
Three Dimensional ◽  
Microwave Imaging

scholarly journals A Subspace Preconditioned LSQR Gauss-Newton Method with a Constrained Line Search Path Applied to 3D Biomedical Microwave Imaging

2015 ◽  
Vol 2015 ◽  
pp. 1-21
Author(s):  
Jürgen De Zaeytijd ◽  
Ann Franchois
Keyword(s):  
Complex Permittivity ◽  
Line Search ◽  
Synthetic Data ◽  
Iterative Solution ◽  
Initial Guess ◽  
Microwave Imaging ◽  
Single Frequency ◽  
Problem Solution ◽  
Source Position ◽  
Search Path

Three contributions that can improve the performance of a Newton-type iterative quantitative microwave imaging algorithm in a biomedical context are proposed. (i) To speed up the iterative forward problem solution, we extrapolate the initial guess of the field from a few field solutions corresponding to previous source positions for the same complex permittivity (i.e., “marching on in source position”) as well as from a Born-type approximation that is computed from a field solution corresponding to one previous complex permittivity profile for the same source position. (ii) The regularized Gauss-Newton update system can be ill-conditioned; hence we propose to employ a two-level preconditioned iterative solution method. We apply the subspace preconditioned LSQR algorithm from Jacobsen et al. (2003) and we employ a 3D cosine basis. (iii) We propose a new constrained line search path in the Gauss-Newton optimization, which incorporates in a smooth manner lower and upper bounds on the object permittivity, such that these bounds never can be violated along the search path. Single-frequency reconstructions from bipolarized synthetic data are shown for various three-dimensional numerical biological phantoms, including a realistic breast phantom from the University of Wisconsin-Madison (UWCEM) online repository.

Microwave imaging by three-dimensional Born linearization of electromagnetic scattering

Radio Science ◽  
1990 ◽  
Vol 25 (6) ◽  
pp. 1221-1229 ◽  
Author(s):  
S. Caorsi ◽  
G. L. Gragnani ◽  
M. Pastorino
Keyword(s):  
Electromagnetic Scattering ◽  
Three Dimensional ◽  
Microwave Imaging

scholarly journals The effective complex permittivity stability in filled polymer nanocomposites studied above the glass transition temperature

2018 ◽  
Vol 149 ◽  
pp. 01080 ◽  
Author(s):  
F. Elhaouzi ◽  
A. Mdarhri ◽  
M. Zaghrioui ◽  
C. Honstettre ◽  
I. El Aboudi ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Complex Permittivity ◽  
Dielectric Response ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Mechanical Analysis ◽  
Low Frequencies ◽  
Neat Polymer

The temperature effecton the dielectric response of nanocomposite at low frequencies range is reported. The investigated samples are formed by a semi-crystalline ethylene-co-butyl acrylate (EBA) polymer filled with three concentrations of the dispersed conducting carbon black (CB) nanoparticles. The temperature dependence of the complex permittivity has been analyzedabove the glass transition temperature of the neat polymer matrix Tg=-75°C. For all CB concentrations, the dielectric spectra follow a same trend in frequency range 100-106Hz. More interestingly, the stability of the effective complex permittivity ɛ=ɛ' -iɛ'' with the temperature range of 10-70°C is explored. While the imaginary part of the complex permittivity ɛ'' exhibits a slight decreasewith temperature, the real part ɛ' shows a significant reduction especially for high loading samples. The observed dielectric response may be related to the breakup of the three-dimensional structurenetwork formed by the aggregation of CB particles causing change at the interfaceEBA-CB.This interface is estimated bythe volume fraction of constrained polymer chain according to loss tangent data of dynamic mechanical analysis.

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