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1

Non-invasive mesurements of transparent fibres

Świrniak Grzegorz

Metrology and Measurement Systems

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2020

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Vol. 27, nr 1

19--31

EN

This paper presents a non-invasive measurement method for simultaneous characterization of diameter and refractive index of transparent fibres. The method is based on scattering of a polychromatic beam of light by a side-illuminated fibre under study. Both quantities of interest are inversely calculated from the scattering far-field region in the vicinity of the primary rainbow. The results of practical measurements are examined with the use of a novel optical system for laboratory-level tests. An analysis of prediction errors for 20–120 μm thick fibres having various refractive indices helps to assess the outcome of the measurement data. The results show a clear route to improve the measurement process in on-line industrial process control.

2

Description of the scattering data for Sturm-Liouville operators on the half-line

Mykytyuk Yaroslav, Sushchyk Natalia

Opuscula Mathematica

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2019

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Vol. 39, no. 4

557--576

EN

We describe the set of the scattering data for self-adjoint Sturm-Liouville operators on the half-line with potentials belonging to [formula], where [formula] is a monotonically nondecreasing function from some family R. In particular, R includes the functions [formula]

3

Variational Bayesian inversion for microwave breast imaging

Gharsalli L., Ayasso H., Duchêne B., Mohammad-Djafari A.

Computer Assisted Methods in Engineering and Science

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2014

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Vol. 21, no. 3-4

199--210

EN

Microwave imaging is considered as a nonlinear inverse scattering problem and tackled in a Bayesian estimation framework. The object under test (a breast affected by a tumor) is assumed to be composed of compact regions made of a restricted number of different homogeneous materials. This a priori knowledge is defined by a Gauss-Markov-Potts distribution. First, we express the joint posterior of all the unknowns; then, we present in detail the variational Bayesian approximation used to compute the estimators and reconstruct both permittivity and conductivity maps. This approximation consists of the best separable probability law that approximates the true posterior distribution in the Kullback-Leibler sense. This leads to an implicit parametric optimization scheme which is solved iteratively. Some preliminary results, obtained by applying the proposed method to synthetic data, are presented and compared with those obtained by means of the classical contrast source inversion method.

4

Radar Signatures of Complex Buried Objects in Ground Penetrating Radar

Panzner B., Jöstingmeier A., Omar A.

International Journal of Electronics and Telecommunications

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2011

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Vol. 57, No. 1

9-14

EN

The evaluation of radar signatures of buried objects for three experimental ground penetrating radar setups will be addressed in this paper. The contribution will present corresponding results and experiences. The performance of the imaging capabilities of the designed radar system will be assessed by reconstruction of complex shaped test objects, which have been placed within the ground. The influence of system parameters of the ground penetrating radar have been varied systematically in order to analyze their effects on the image quality. Among the modified parameters are the step size in transverse plane, height of the antenna over ground, frequency range, frequency points, antennas and varying instrument settings. A signal processing technique based on synthetic aperture radar has been applied on the measured raw data. The focus radius around a specific target has been analyzed concerning the compromise between image quality and processing time. The experiments demonstrate that the designed ground penetrating radar systems are capable for detection of buried objects with high resolution.