Liste des communications
Human Liver Tissue Characterization Using Backscattered Ultrasound Signals Mean Scatterer Spacing
Using the backscattered ultrasound signals, we studied the periodicity of in vitro healthy and pathological liver tissue, we utilized the mean scatterer spacing (MSS) as a parameter of tissue characterization, estimated by: Spectral Auto-Correlation (SAC), Spectral Correlation of the autoregressive model (AR-SAC) and the Discrete Wavelet Technique (DWT), in comparison between this three method, the result of simulation confirm that DWT with Fourier Transform together (DWT with FT) can provide a very effective tool to extract the MSS from such structure and characterize the tissue. Voir les détails
Mots clés : Periodicity, Liver tissue, Mean scatterer spacing, Backscattered Ultrasound Signals
PREPARATION OF ELABORATION AND CHARACTERIZATION OF CdZnS THIN FILMS DEPOSED BY CHEMICAL BATH DEPOSITION
This work involves the development of thin films of CdxZn1-xS on glass substrates for photovoltaic applications, solar cells. The thin buffer CdZnS was synthesized by chemical bath (CBD), with different deposition protocols, studies the parameters influencing these layers as the temperature, deposition time and pH. The structural and optical properties of various thin films are studied and in relation to the photovoltaic performance. This work is a contribution in the field of thin films, to revive the CdZnS a new air of research and its introduction to nanotechnology. The different structural, morphological and optical analyzes yielded very interesting results. Voir les détails
Mots clés : CdZnS, chemical bath, Thin films, solar cells.
Reconstitution of complex defects with the methodof neural network: Application for the nondestructiveevaluation
in this work, we propose a reconstitution of complex defects starting from the results obtained during a nondestructive testing by eddy currents carried out on aconducting plate by using the neural network. We provided tothe neural network the values of impedance of the differential sensor calculated using a modeling by finite elements.The values of impedance are injected at the input of the neural network and the depth of the defect is recovered in its output, we used the gradient of the error propagation algorithm for performing learning of the neural network. Voir les détails
Mots clés : Neural Network, eddy currents, impedance, complex defect, nondestruction evaluation
Non intrusive stochastic finite elements method applied for non destructives NDT problems
The current work concerns the study of harmful defect detection for the inspected structure by eddy current non destructive testing. So a non intrusive stochastic finite element method was exploited in the case of 2D magnetodynamic equation. The electrical conductivity is considered as random variables and generated using Monte -Carlo method. Voir les détails
Mots clés : Stochastic finite element method, Eddy Current, Conducting plate, Random variable
Temperature Effects on Thin film Based SPR-Sensor
In this paper, using the angle interrogation methods, we simulate the effect of temperature fluctuation on thin film based SPR-sensor. The sensor configuration is a three layer Krestchmann configuration consisting of glass prism, thin metallic layer, and bulk sensing layer. The temperature sensor uses RPS geometry of three interfaces where the refractive index of the layer adjacent to the environment is very sensitive to changes in the environmental temperature. The final results indicate that, as the temperature decreases, Θmin (resonance angle) shift to larger angles and increased in Rmin .These results can be used in the development of chemical, biomedical sensors, is suggested Voir les détails
Mots clés : surface plasmon resonance (SPR), thermo-optic effect, temperature sensor.
Non-destructive testing of cover concrete using spectral analysis of ultrasonic surface waves
Concrete cover evaluation with NDT technique is a critical issue in the diagnosis of structures service life. Ultrasonic NDT technique is one of the most efficient techniques for concrete strength evaluation. This paper presents the use of spectral analysis of ultrasonic surface waves for the non destructive evaluation of concrete cover in laboratory. The procedure consists in generation and reception of surface waves using the time of flight diffraction method. After extraction of the lateral wave in the received signal using the matching pursuit method, the phase velocity dispersion characteristic is determined, and concrete cover is characterized. Voir les détails
Mots clés : Time of flight diffraction, matching pursuit, concrete cover
Estimation of ultrasonic wave parameters in materials under bending force
this paper presents the use of prism technique todetermine the longitudinal and transversal wave parameters in materials under simple bending forces. The weak number of studies on acoustoelastic behavior and the evolution of measurement methods led us to propose a complete feasibility study on measurements of longitudinal and shear waves for different mediums subjected to uniaxial compressive stresses.The expectation maximization algorithm is employed for parameters estimation those are amplitude, phase, time of flight, frequency and bandwidth. These parameters allow the verification of the parameter values modification resulting from the effect of bending stresses. Voir les détails
Mots clés : Ultrasonic, prism technique, expectation maximization algorithm
PROPRIETES ELECTRONIQUES DES NANOCOMPOSITES Ni/MgO
Le but de ce travail est d'étudier les propriétés électronques des nanocomposites Ni/MgO, obtenus par imprégnation avec échange ionique, suivie soit d’une irradition gamma, soit d’une calcination diverses températures (T=100-600°C). La diffraction des rayons X a révélé la formation de l’hydroxyde de magnésium après l’étape d’imprégnation. Après traitement thermique, cette phase disparait au détriment de composés intermétalliques Mg-Ni (Mg2Ni, Mg6Ni et Ni2Mg), qui à leurs tour disparraissaient audela de 300°C.L’étude ds propriétés électroniques des composites Ni/MgO par la spectroscopie (XPS), a confirmer la formation de composés intermétalliques Ni-Mg, et qui affecte l’energie de liaison de l’oxyde de nickel (NiO) détécté en surface. Voir les détails
Mots clés : Ni-MgO, nanoparticules, XPS
Fast Finite Element Computation for 3D Eddy Current Testing Problems with T-Ω Formulation
The paper deals with T-Ω formulation modeling of eddy current problems. The method is applied to the analysis of 3D eddy current testing of metallic plate with cracks, and the usefulness of the method is investigated by comparing calculated results with measured ones. Voir les détails
Mots clés : nondestructive testing, Eddy Current, Cracks, T-Ω formulation, 3D finite element.
Study of the Effet of the Geometry Shape of defecton the Reliability of NDT Device
This work concerns the study the effect of random properties and defect geometry on the reliability analysis ofthe non-destructive testing inspection device. Two kinds ofdefects geometries are considered as rectangle and triangle shapes respectively. A stochastic finite element method (SFEM) was used to solve the 2D electromagnetic equation incylindrical structure. The results obtained for both rectangle and triangle random shapes are given. Voir les détails
Mots clés : random geometry, random propertie, nondestructive testing, reiability analysis, stochastic finite elements