Joseph Moysan

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-In this paper we present innovative research for the processing of an ultrasonic image obtained in non-destructive testing (NDT). We also present an algorithm for automatic thresholding segmentation. The image analysis is based on the calculation of cooccurrence matrices. The method we used is the Spatial Grey-Level Dependence Method (SGLDM); it shows the(More)
Nonlinear resonant ultrasound spectroscopy (NRUS) consists of evaluating one or more resonant frequency peak shifts while increasing excitation amplitude. NRUS exhibits high sensitivity to global damage in a large group of materials. Most studies conducted to date are aimed at interrogating the mechanical damage influence on the nonlinear response, applying(More)
The knowledge of the anisotropic and heterogeneous behaviour of the material is the key point for understanding ultrasonic testing. In the case of austenitic stainless steel multipass welds, there was no exact knowledge. The succession of passes and complex solidification processes makes the modelling of the resulting grain orientation difficult. The MINA(More)
Research studies are currently being conducted to understand the phenomena governing the acoustic coupling of ultrasonic transducers immersed in liquid sodium in relation to the development of a Generation IV sodium-cooled fast reactors (SFR). The gas surface fraction at a solid/liquid interface determines the amount of acoustic energy that can be(More)
A new application of data fusion is presented within the context of national research project named SENSO. The aim is to improve evaluation of indicators or pathologies of in situ concrete structures by combining measurements from different NDE techniques (radar, electrical resistivity and capacity, infrared thermography, impact echo and ultrasounds). Every(More)
The characterization of argon microbubbles in liquid nitrogen is currently being investigated in connection with the development of Generation IV nuclear reactors. It seems that non-linear acoustic techniques can be used to determine the void fraction (volumetric fraction of free gas) and the histogram of the bubble radiuses. We discuss the first stage of(More)
In the case of multi-pass welds, the material is very difficult to describe due to its anisotropic and heterogeneous properties. Anisotropy results from the metal solidification and is correlated with the grain orientation. A precise description of the material is one of the key points to obtain reliable results with wave propagation codes. A first advance(More)
In some austenitic stainless steel welds grains orientations cause deviation and splitting of the ultrasonic beam. It is especially true in the case of multipass welds when the remelting process after each pass causes complex solidification process. With the new model MINA (Modelling anisotropy from Notebook of Arc welding) we show that we are able to(More)
We study the development potential of ultrasonic thermometry in a liquid fluctuating sodium environment similar to that present in a Sodium-cooled Fast Reactor, and thus investigate if and how ultrasonic thermometry could be used to monitor the sodium flow at the outlet of the reactor core. In particular we study if small temperature variations in the(More)