Uncertainty on fringe projection technique: a Monte-Carlo-based approach

International audienceError estimation on optical full field techniques (OFFT) is millstone in the diffusion of OFFT. The present work describes a generic way to estimate overall error in fringe projection, either due to random sources (phase error, basically related to the quality of the camera and of the fringe extraction algorithm) or the bias (calibration errors). Here, a high level calibration procedure based on pinhole model has been implemented. This model compensates for the divergence effects of both the video-projector and the camera. The work is based on a Monte Carlo procedure. So far, the complete models of the calibration procedure and of a reference experiment are necessary. Here, the reference experiment consists in multiple step out-of-plane displacement of a plane surface. Main conclusions of this work are: 1/ the uncertainties in the calibration procedure lead to a global rotation of the plane, 2/ the overall error has been calculated in two situations; the overall error ranges from 104 µm down to 10 µm, 3/ the main error source is the phase error even if errors due to the calibration are not always negligible

Role of Proteins on the Electrochemical Behavior of Implanted Metallic Alloys, Reproducibility and Time-Frequency Approach from EIS (Electrochemical Impedance Spectroscopy)

Metallic alloys are commonly used in orthopedic implants. Some attempts were investigated for replacing the human organs or joints. Without being exhaustive, some key points of the history of the orthopedic implants could be presented (Callaghan, 2007): - In 1826, the first pseudoarthrosis was practiced by J. Barton with a wood piece of the hip joint; - In 1891, the first femoral head in ivory was implanted by T. Gluck (Gluck, 1890); - In 1923, the "Molded arthroplasty" using hollow hemisphere made of glass was practiced by M.N. Smith-Petersen; - In 1936, the first acrylic femoral stem was implanted by Judet's brothers. One might suggest the implanted materials are close to the organic materials in terms of natural origin. The last one, acrylic polymer, would be a dedicated material because their mechanical properties are close to the ones of bone. However the mechanical and tribological properties are not sufficient for being enough resistants. Thus the metallic implants were investigated because of their better mechanical properties, elastic modulus and tensile strength. Following, few important dates are suggested: - In 1938, M.N. Smith-Petersen used the Vitallium® made of Co-Cr-Mo, Cobalt-Chromium-Molybdenum, alloy for the femoral stem; - In 1949, Judet's brothers implanted the first total hip arthroplasty (Judet, 1949); - Finally, in 1962, Sir J. Charnley imposed the low friction arthroplasty with a femoral stem made of 316L stainless steel (Charnley, Livingstone, 1970; Charnley, Springer, 1970).Finally 3 main materials are implanted as femoral stem or metallic components: the titanium alloy, Ti-6Al-4V, the stainless steel, 316L SS, and the cobalt-chromium alloy (Park, 1992). The first one is dedicated to the femoral stem, the second one is used as material for manufacturing femoral stem, metal back and possibly the head for Metal on Polymer, MoP, contact, the third metal could be investigated as the Head and cup assembly for Metal on Metal, MoM, assembly, the head component for MoP assembly and no frequently the femoral stem. Figure 1 highlights the different assemblies involved in the femoral stem. The ceramic material will not be presented in this work

Influence of proteins from physiological solutions on the electrochemical behaviour of the Ti-6Al-4V alloy: reproducibility and time-frequency dependence. ---- Influence de la teneur en prot\'eines de solutions physiologiques sur le comportement \'electrochimique du Ti-6Al-4V : reproductibilit\'e et repr\'esentation temps-fr\'equence

The electrochemical behaviour of the biomedical and metallic alloys, especially in the orthopaedic implants fields, raises many questions. This study is dedicated for studying the Ti-6Al-4V alloy, by electrochemical impedance spectroscopy, EIS, in various physiological media,: Ringer solution, phosphate buffered solution (PBS), PBS solution and albumin, PBS solution with calf serum and PBS solution with calf serum and an antioxidant (sodium azide). Moreover, the desionised water was considered as the reference solution. The tests reproducibility was investigated. The time-frequency-Module graphs highlighted that the desionised water is the most protective for the Ti-6Al-4V alloy. This biomedical alloy is the less protected in the solution constituted by PBS and albumin. The time-frequency graph allows pointing out the graphic signatures of adsorption for organic and inorganic species (differences between the modules means in studied solution and the modules mean in the reference solution). --- Le comportement \'electrochimique des alliages m\'etalliques biom\'edicaux, notamment dans le domaine des implants orthop\'ediques, pose encore de nombreuses questions. Ce travail propose d'\'etudier l'alliage de titane Ti-6Al-4V, par spectroscopie d'imp\'edance \'electrochimique, SIE, dans diff\'erents milieux physiologiques : solution de Ringer, solution \`a base d'un tampon phosphate (PBS), solution PBS avec de l'albumine, solution PBS avec du s\'erum bovin et une solution PBS avec du s\'erum bovin et un antioxydant (azoture de sodium). De plus, une solution d'eau ultra-pure servira de r\'ef\'erence. La reproductibilit\'e des tests a \'et\'e \'etudi\'ee. Les repr\'esentations temps-fr\'equence des modules ont mis en \'evidence que l'eau d\'esionis\'ee est la solution qui pr\'esente le caract\`ere le plus protecteur pour le Ti-6Al-4V. Cet alliage de titane est le moins prot\'eg\'e dans la solution de PBS contenant de l'albumine. Cette repr\'esentation permet de mettre en \'evidence des signatures graphiques d'adsorption des esp\`eces inorganiques et organiques (diff\'erences entre les moyennes des modules dans les solutions \'etudi\'ees et la moyenne des modules dans la solution de r\'ef\'erence)

Wavelet Analysis of the Turbulent LES Data of the Lid-Driven Cavity Flow

International audienceBoth Fourier and wavelet transforms are performed on data obtained from large-eddy simulations of the turbulent flow in a lid-driven cubical cavity. The analyzed data or synthetic signals are picked at three specific points inside the cavity allowing to investigate three regimes over time: laminar, transitional and turbulent. The main objective of this study is to generate and analyze synthetic signals in order to confirm the correlation between the computed physical quantities and those expected theoretically

Semi-automatic Endogenous Enrichment of Collaboratively Constructed Lexical Resources: Piggybacking onto Wiktionary

International audienceThe lack of large-scale, freely available and durable lexical resources, and the consequences for NLP, is widely acknowledged but the attempts to cope with usual bottlenecks preventing their development often result in dead-ends. This article introduces a language-independent, semi-automatic and endogenous method for enriching lexical resources, based on collaborative editing and random walks through existing lexical relationships, and shows how this approach enables us to overcome recurrent impediments. It compares the impact of using different data sources and similarity measures on the task of improving synonymy networks. Finally, it defines an architecture for applying the presented method to Wiktionary and explains how it has been implemented

Efficiency and comfort of knee braces: A parametric study based on computational modelling

International audienceKnee orthotic devices are widely proposed by physicians and medical practitioners for preventive or therapeutic objectives in relation with their effects, usually known as to stabilize joint or restrict ranges of motion. This study focuses on the understanding of force transfer mechanisms from the brace to the joint thanks to a Finite Element Model. A Design Of Experiments approach was used to characterize the stiffness and comfort of various braces in order to identify their mechanically influent characteristics. Results show conflicting behavior: influent parameters such as the brace size or textile stiffness improve performance in detriment of comfort. Thanks to this computational tool, novel brace designs can be tested and evaluated for an optimal mechanical efficiency of the devices and a better compliance of the patient to the treatment

Hyperbolic Wavelet-Fisz denoising for a model arising in Ultrasound Imaging

International audienceWe present an algorithm and its fully data-driven extension for noise reduction in ultrasound imaging. Our proposed method computes the hyperbolic wavelet transform of the image, before applying a multiscale variance stabilization technique, via a Fisz transformation. This adapts the wavelet coefficients statistics to the wavelet thresholding paradigm. The aim of the hyperbolic setting is to recover the image while respecting the anisotropic nature of structural details. The data-driven extension removes the need for any prior knowledge of the noise model parameters by estimating the noise variance using an isotonic Nadaraya-Watson estimator. Experiments on synthetic and real data, and comparisons with other noise reduction methods demonstrate the potential of our method at recovering ultrasound images while preserving tissue details. Finally, we emphasize the noise model we consider by applying our variance estimation procedure on real images