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Reims, France

Maxel X.,Ecole Superieure dOsteopathie | Bodnar J.L.,GRESPI | Stubbe L.,Ecole Superieure dOsteopathie
Mechanics and Industry | Year: 2014

The aim of this study is to approach the possibilities of stimulated infrared thermography to the carpal tunnel syndrome diagnosis. Eleven patients were studied. Six of them were affected by the carpal tunnel syndrome. The five others were healthy. The study consists in exciting the patients' hands and in analyzing their thermal response. The infrared thermograms obtained show that the hands infected by the carpal tunnel syndrome give a different thermal response. © AFM, EDP Sciences 2014. Source

The influence of changes of the work function, φ, or electron affinity, χ, on the escape probability, A, of Secondary Electrons, SE, is derived from their angular and energy distributions, respectively ∂δ/ ∂α and ∂δ/∂Ek. Based on the evaluation of the spectral distribution of inner SEs, the present approach quantifies the dominant role of potential barrier on the SE emission and its change with surface treatments or thin film deposits. For instance it is shown that a 1 eV-increase of φ for Au leads to a decrease of A, and then of SE emission yield, δ, of about 50% while a 0.4 eV-increase of χ for potassium chloride induces a decrease of a factor 4 for A and then for the SEE yield δ. These results are summarized by empirical expressions of form A/A° = (φ/φ°)-3 for Au and A/A° =(χ/χ°) -3/2 for KCl. Applied here to an insulating sample and to a metal, the present approach may be easily transposed to any kind of material of known Fermi energy and work function, metals, or known affinity, semiconducting and insulating samples. The large SEE yield values of inorganic insulators relative to that of metals are explained by larger values of their escape probability A - KCl: A° ∼ 25% for χ° = 0.6 eV; Au: A° ∼ 4% for φ° = 3.5 eV - combined to larger SE attenuation lengths and despite a less SE generation factor. This approach underlines the significant role of A on the large deviations between SEEY data as reported in literature and a strategy combining in situ δ and φ measurements is suggested to partly compensate the corresponding dispersion of experimental results. The present approach may be transposed to other energetic projectiles such as X-rays or ions and some practical consequences related to Scanning Electron Microscopy, mechanisms of contamination and crystalline contrasts, are pointed out. © 2010 Elsevier B.V. All rights reserved. Source

Bouteille P.,CETIM | Legros G.,CETIM | Walaszek H.,CETIM | Bodnar J.L.,GRESPI
Mechanics and Industry | Year: 2014

In this work, we approach the possibilities of infrared thermography for non-destructive testing of metallic materials. We show that the passive alternative of the method makes it possible to improve detection of surface defects existing in deep-drawn parts and visible to the naked eye. We then show that active infrared thermography, in particular coupled with induction excitation, can replace in certain cases the magnetic particle inspection, allowing the detection of very fine defects in forged parts. Finally, the study of a stepped block confirms the possibilities of active infrared thermography to detect defects not open to the surface and underlying defects. © 2014 AFM, EDP Sciences . Source

The bearing is one of the most important components of rotating machines. Nevertheless, in normal conditions of use, it is subject to fatigue which creates a defect called a rolling fatigue spalling. In this work, we present a follow-up of the thrust bearing fatigue on a test bench. Vibration analysis is a method used to characterize the defect. In order to obtain the fatigue curve more adjusted, we have studied the vibration level according to statistical indicators: the Root Mean Square value (RMS value), which is one of the best indicators to show the evolution of the bearing degradation. The approach follows the working of the bearing until the degradation with an on line acquisition of vibration statements in form of time signals. With the signal treatment, we obtain the values of the vibration amplitudes which characterize the vibration state of the bearing. Consequently, these values allow us to plot the fatigue curves. During our experimental work, this operation is applied for a batch of thrust bearings for which we have obtained similar fatigue curves where the evolution trend follows a regression model from the detection of the onset of the first spall. The result of this work will contribute to predict the working residual time before failure. © 2013 AFM, EDP Sciences. Source

Mouhoubi K.,GRESPI | Bodnar J.L.,GRESPI | Ousseni S.,GRESPI | Nicolas J.L.,GRESPI | Caron D.,GRESPI
Mechanics and Industry | Year: 2014

In this paper, we consider the possibilities of the stimulated infra-red thermography for local metallic sample thermal characterization. At first we introduce the measurement principle, which is based on the local measurement of the thermal diffusivity parameter. Then, using simulations, we demonstrate the feasibility of the method. We then present the experimental device implemented for the study. Finally, we show that this approach allows a good estimation of the thermal diffusivity of a metal sample. © 2014 AFM, EDP Sciences . Source

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