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A new method to determine fluid flux at high pressures and temperatures has been developed and used to study serpentinites at subduction zone conditions. Drill cores of a natural antigorite‐serpentinite with a strong foliation were used in multi‐anvil experiments in the range of 2–5 GPa and 450–800°C. Fluids released upon dehydration are fixed by the formation of brucite in an adjacent fluid sink. The amount and distribution of brucite serves as a proxy for fluid flow. In our specific setup the sample reacted with the surrounding fluid sink to form an additional layer of olivine, which has the potential to limit fluid flux within our experiments. For conditions prior to serpentine dehydration we used Al(OH)3 as fluid source. Fluid in this experiment did not migrate through the serpentinite, indicating that serpentine has a low diffusivity. The experiments also show that small deviatoric stresses have an influence on the fluid flux and can cause an anisotropic fluid flux. Comparison between the time scales of the determined fluid flux with fluid production rates indicates fluid pressure buildup during dehydration reactions. Adjacent less permeable layers can inhibit fluid flux and cause fluid pressure buildup even at conditions when an interconnected pore space formed., Plain Language Summary: Subduction zones are regions where tectonic plates are recycled into the Earth's interior. Prior to subduction, the plates experienced extensive chemical interaction with the ocean water, forming hydrous minerals. Serpentine is an important hydrous mineral that can transport significant amounts of water into the Earth's interior. During subduction both pressure and temperature increase whereby hydrous minerals break down and release their water. The fluid migrates into the overlying mantle wedge, where it accounts for hydration as well as melting processes. The global flux balances would require this process to be very effective. However, it was so far not possible to measure the fluid flux at the subduction zone conditions in laboratories. In this study, we present a new method to determine the fluid flux prior and during dehydration. We found that prior to dehydration, the fluid flux in serpentinites is small. During dehydration the rocks ability to let fluids pass through increases. However, adjacent rocks with a low ability for fluid transport can further inhibit a fluid flux at these conditions. Generally, our experimental setup can be used for any system that immobilizes migrating fluids by hydration reactions., Key Points: A new method to determine fluid flux at high pressure and temperature conditions is developed. Slow fluid migration in serpentinites promotes brittle fracturing in subduction zones. Fast fluid migration upon dehydration of serpentinites promotes large‐scale fluid flux, if not inhibited by adjacent less permeable layers., Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659, JSPS Japanese‐German Graduate Externship, Nederlandse Organisatie voor Wetenschappelijk Onderzoek http://dx.doi.org/10.13039/501100003246, https://doi.org/10.24416/UU01-PB440D

Elastic properties of B2‐Fe0.67Ni0.06Si0.27 (15 wt.% Si) alloy have been investigated by combined high‐resolution inelastic X‐ray scattering and powder X‐ray diffraction in diamond anvil cells up to 100 GPa at room temperature. Densities (ρ), compressional (VP) and shear (VS) wave velocities were extrapolated to inner core conditions to enable comparison with the preliminary reference Earth model. The modeled aggregate compressional and shear wave velocities and densities of the two‐phase mixture of B2‐Fe0.67Ni0.06Si0.27 and hcp‐Fe‐Ni are consistent with inner core PREM values of VP, VS, and ρ based on a linear mixing model with 30(5) vol % B2‐Fe0.67Ni0.06Si0.27 and 70(5) vol % hcp Fe‐Ni, which corresponds to ∼3–5 wt.% Si and ∼5–12 wt.% Ni., Plain Language Summary: The composition of the inner core holds key information about how Earth evolved and how current processes such as the geomagnetic field work. Because the core cannot be directly sampled, our best estimates of its composition are based on the comparison of geophysical data with laboratory measurements of candidate materials. Decades of study have shown the inner core to be composed mainly of iron (with a minor amount of nickel) alloyed with one or more light elements, such as silicon. However, the effect of Si on the geophysical properties of Fe‐Ni alloys is not well established. In this study, we performed laboratory experiments to determine the density and sound velocity of Fe‐Ni‐Si alloy under extreme pressure conditions. We compared our results with seismological determinations and found that Earth's inner core can be accounted for by a mechanical mixture of cubic Fe‐Ni‐Si and hexagonal Fe‐Ni alloys. This mixture has a bulk composition of ∼3–5 weight % Si and ∼5–12 weight % Ni and is consistent with geophysical constraints., Key Points: Sound velocities and densities of B2‐Fe‐Ni‐Si alloy are determined at high pressure, up to 100 GPa, using inelastic X‐ray scattering and X‐ray diffraction. Seismologically observed compressional and shear wave velocities and density of Earth's inner core can be accounted for by a two‐phase mixture of 30 vol % B2‐Fe‐Ni‐Si and 70 vol % hcp Fe‐Ni alloys. Extrapolated results at inner core boundary conditions are consistent with an inner core composition containing ∼3–5 wt.% Si and ∼5–12 wt.% Ni., Japan Society for the Promotion of Science http://dx.doi.org/10.13039/501100001691, Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659, JSPS Japanese‐German graduate externship, https://doi.org/10.6084/m9.figshare.13370795.v1, https://doi.org/10.6084/m9.figshare.13370792.v1

To explore the dynamic mechanism of continental rifting within a convergent setting, we determine the first P wave radial anisotropic tomography beneath the Woodlark rift in southeastern Papua New Guinea, which develops within the obliquely colliding zone between the Australian and southwest Pacific plates. The rift zone is depicted as localized low‐velocity anomalies with positive radial anisotropy, which rules out a dominant role of active mantle upwelling in promoting the rift development and favors passive rifting with decompression melting as main processes. Downwelling slab relics in the upper mantle bounding the rift zone are revealed based on observed high‐velocity anomalies and negative radial anisotropy, which may contribute to the ultra‐high pressure rock exhumations and rift initiation. Our observations thus indicate that the Woodlark rift follows a passive model and is mainly driven by slab pull from the northward subduction of the Solomon plate., Plain Language Summary: The Woodlark rift in Papua New Guinea develops within the shear zone between the Australian and southwest Pacific plates and is one of the youngest and most rapidly extending continental rifts in the world. In this work, we analyze teleseismic P wave arrivals to study both 3‐D velocity and radial anisotropy structures of the upper mantle, offering new evidence to understand rift initiation under a generally convergent setting. Slab remnants in the upper mantle bordering the rift zone are detected and sinking into the deeper mantle. Downwelling of these slab segments may induce small scale return flows in the mantle and contribute to exhumation of the ultra‐high pressure rocks and rift development. Significant low‐velocity anomalies are revealed beneath the rift zone and have consistently positive radial anisotropy, which indicates a dominant strain in the horizontal plane and supports a passive rifting model, where mantle material is brought to shallower depths simply as a result of the extension of the lithosphere and melt is produced due to the lowered melting point at reduced pressure (decompression melting). Tensional stresses transferred from slab pull of the northward Solomon subduction are probably driving the rifting., Key Points: P wave radial anisotropic structure beneath the young and highly extended Woodlark rift is constrained from teleseismic tomography. Downwelling of slab relics bordering the rift zone may contribute to ultra‐high pressure rock exhumation and rift development. Slab‐pull drives rift initiation and induces decompression melting in the upper mantle under the rift zone by horizontal stress transfer., National Natural Science Foundation of China (NSFC) http://dx.doi.org/10.13039/501100001809, National Science Foundation (NSF) http://dx.doi.org/10.13039/100000001, MEXT | Japan Society for the Promotion of Science (JSPS) http://dx.doi.org/10.13039/501100001691, Alexander von Humboldt‐Stiftung (Humboldt‐Stiftung) http://dx.doi.org/10.13039/100005156, https://doi.org/10.7914/SN/XD_1999, https://doi.org/10.7914/SN/ZN_2010

A comprehensive review of physics at an e+e- Linear Collider in the energy range of sqrt{s}=92 GeV--3 TeV is presented in view of recent and expected LHC results, experiments from low energy as well as astroparticle physics.The report focuses in particular on Higgs boson, Top quark and electroweak precision physics, but also discusses several models of beyond the Standard Model physics such as Supersymmetry, little Higgs models and extra gauge bosons. The connection to cosmology has been analyzed as well., 179 pages, plots and references updated, version to be published at EPJC

We estimate the presently unknown constant in the 4-loop relation between the quark pole mass and the MS¯ mass, by requiring stability of the perturbative prediction for Etot(r)=2mpole+VQCD(r) in the intermediate-distance region. The estimate is fairly sharp due to a severe cancellation between 2mpole and VQCD(r). This would provide a test, based on general properties of the gauge theory, for the size of ultra-soft contributions to VQCD(r).

International audience; Physical and social activities should be included in an efficient e-coaching for older adults and immersive virtual reality (IVR) is efficient if behavioral changes are transferred to the real physical world. In an experiment con-ducted with 42 older adults (63-85 years-old), participants were asked to interact with a specific immersive virtual reality (IVR) daily for 4 months in their homes, at least 15 minutes per day. Results demonstrate several positive impacts related to the use of the IVR (decrease of weight, decrease of waist circumference, number of steps outside) even if the time spent to use this IVR system decreases. So, the transfer from the IVR to the real world is very encouraging.

International audience; Computational fluid dynamics (CFD) is a key tool for a wide range of research areas, beyond the computer science community. In particular, CFD is used in medicine to measure blood flow from patient specific models of arteries. In this field, the creation of accurate meshes remains the most challenging step, as it is based on the segmentation of medical images, a time-consuming task which often requires manual intervention by medical doctors. In this context, userfriendly, interactive softwares are valuable. They enable to spread the new advances in numerical treatment to the medical community and enrich them with the expert knowledge (e.g anatomical knowledge) of clinicians. In this work, we present a user interface dedicated to the meshing of vascular networks from centerlines. It allows for the 3D visualization and edition of input centerlines, which constitute a simplified, easy-tomanipulate representation of vascular networks. The surface of the artery can be reconstructed from the modified centerlines by an editable parametric model and then meshed with high quality hexahedral elements. At every step of the process, the network can be confronted with medical images with enhanced visualization. The software will be released publicly. Clinical relevance - This tool facilitates the manual extraction and editing of vascular networks by medical doctors. It opens the generation of hexahedral meshes for computational fluid dynamics studies to non-expert users.

IntroductionDespite a decade of research into virtual stent deployment and the post-stenting aneurysmal hemodynamics, the hemodynamic factors which correlate with successful treatment remain inconclusive. We aimed to examine the differences in various post-treatment hemodynamic parameters between successfully and unsuccessfully treated cases, and to quantify the additional flow diversion achievable through stent compaction or insertion of a second stent.MethodsA systematic review and meta-analysis were performed on eligible studies published from 2000 to 2019. We first classified cases according to treatment success (aneurysm occlusion) and then calculated the pooled standardized mean differences (SMD) of each available parameter to examine their association with clinical outcomes. Any additional flow diversion arising from the two common strategies for improving the stent wire density was quantified by pooling the results of such studies.ResultsWe found that differences in the aneurysmal inflow rate (SMD −6.05, 95% CI −10.87 to −1.23, p=0.01) and energy loss (SMD −5.28, 95% CI −7.09 to −3.46, pConclusionsInflow rate and energy loss have shown promise as identifiers to discriminate between successful and unsuccessful treatment, pending future research into their diagnostic performance to establish optimal cut-off values.

International audience; Polymer coating by cold-spray presents interesting features such as the possibility to protect metallic substrates or to add functionalities to a structure. However, it is characterized by a low deposition efficiency and a weak interface between the substrate and the coating. In this study, we performed fluoropolymer coatings by the cold-spray process. Analysis of the particle deposition during cold-spray highlighted the importance of the particle size, substrate temperature, and inlet gas temperature and pressure on the adhesion polymer/substrate. The addition of hydrophobized fumed nano-ceramics (FNC) to the polymer feedstock enhances the deposition efficiency and polymer adhesion on the substrate. The addition of fumed nano-alumina (FNA) to the polymer feedstock tends to give better results than fumed nano-silica in terms of deposition efficiency thanks to (i) the difference of surface charge leading to the attractive force between the polymer and the FNA during the powder preparation stage, and (ii) a homogeneous repartition of the FNA on the polymer particle surface. In addition, the hydrophobization of the FNC maintains and enhances the hydrophobicity and water repellency properties of the fluoropolymer coating.

International audience; By using a qualitative method (focus group) with 42 seniors, this exploratory study is aiming to investigate attitudes and opinions of seniors about five types of trainers/coaches (self-training, human personal trainer, robot, virtual immersion, E-coach) to promote physical activity. Our results tend to confirm that a hybrid solution such as an E-coach (combining human appearance and digital dimensions) could be the most relevant and acceptable for elderly people to promote and maintain physical activity at home.

International audience; This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution.It is well known that physical exercise has beneficial effects on cognitive function in older adults. Recently, several physical exercise programs with virtual reality (VR) have been proposed to support physical exercise benefits. However, it is still unclear whether VR physical exercise (VR-PE) has positive effects on cognitive function in older adults. The purpose of this study was to conduct a systematic review (SR) of the effects of VR-PE on cognitive function in older adults with and without cognitive decline. We used academic databases to search for research papers. The criteria were intervention study using any VR-PE, participants were older adults with and without mild cognitive decline (not dementia), and cognitive functions were assessed. We found that 6 of 11 eligible studies reported the significant benefits of the VR-PE on a wide range of cognitive functions in aging populations. The SR revealed that VR-PE has beneficial effects on the inhibition of executive functions in older adults with and without mild cognitive decline. Moreover, VR-PEselectively leads to improvements in shifting and general cognitive performance in healthy olderadults. The SR suggests that VR-PE could be a successful approach to improve cognitive function inolder adults with and without cognitive decline.

International audience; For the first time, the low-pressure cold spray (LPCS) process was used to manufacture Gallium Nitride (GaN) films to enhance its photocatalytic properties and decrease its manufacturing cost. The deposition behavior of the GaN powder on stainless steel substrates was investigated. Several specimens, with sparsely deposited agglomerated GaN particles, were prepared under different spray conditions. Quantitative analysis of the evolution of the coverage area, deposited particle count, and average sectional area shows that, upon impact, agglomerated GaN particles disintegrate, leading to large deposition of small particles. By analyzing the cross-sectional area of the deposited 2 particle, no discernible permanent deformation of the substrate was observed. In addition, X-ray diffraction analysis of the coatings and powder indicated that no phase transformation occurred during the process. Based on Williamson-Hall analysis, the broader peaks of the coatings were mainly attributed to the distortions in the GaN lattice rather than changes in the crystallite size. At 400°C and 0.6 MPa, the deposition efficiency reached 5.3%, and the photocatalytic activities of the coating were about 33% (+9% compared to the powder). It is attributed to the higher specific surface area and roughness that the coatings exhibit after the breakage of the particles during the cold spray.

ObjectivesTreating intracranial aneurysms with flow-diverting stents sometimes requires deployment of a second device. Herein we quantify the sizing effects of devices in dual-stent treatments upon the final stent microstructure and the post-treatment aneurysmal haemodynamics.MethodsFifteen sidewall ICA aneurysm geometries were included. Using a virtual stenting technique, we implanted either one or two stents for each aneurysm treatment considered, with each stent specified as one of two different sizes, yielding a total of two single-stent and fouir dual-stent treatment scenarios for each aneurysm. Three stent microstructural parameters and nine aneurysmal haemodynamic parameters were quantified and systematically compared across the 90 treatment scenarios.ResultsDeployment of a second stent further reduced the aneurysmal inflow rate (IR) and energy loss (EL) by, respectively, 14 ± 11% (p = 0.001) and 9 ± 12% (p = 0.056), relative to the untreated condition. Sizing effects of the earlier-deployed stent led to largest differences of 6.9% for the final IR reduction and 11.1% for the EL, whereas sizing effects from the later-deployed stent were minor (≤2.1%). The change in stent pore size was the only microstructural parameter demonstrating a strong correlation with the reduction in the post-treatment aneurysmal haemodynamics, in terms of the IR (r = 0.50, p < 0.001) and pressure drop (r = 0.63, p < 0.001).ConclusionSize of the earlier-deployed stent has substantial effects on the final haemodynamic outcomes after dual-stent treatment. The average pore size of stent wires at the aneurysm orifice shows promise as a potential index for predicting the efficacy of flow-diversion treatments.

International audience; This study proposes a probability of detection (POD) model for the probabilistic analysis of the detectability of electromagnetic acoustic resonance (EMAR) method for the detection and evaluation of pipe wall thinning. Forty-one carbon steel plate samples with an artificially corroded groove were prepared to simulate pipe wall thinning caused by flow-assisted corrosion. Experiments were performed to gather EMAR signals from the samples, and subsequently the depths of the grooves were evaluated based on the fundamental frequency of the measured signals. The results of the experiments showed that the error in evaluating the depth of a groove tended to increase with the depth. The results also confirmed that the surface roughness of the groove would contribute to the error, and the thickness of a plate without corrosion can be quite accurately evaluated. Analyzing the measured EMAR signals using the proposed POD model, which takes these characteristics into consideration, and a conventional one confirmed that the proposed model can more reasonably evaluate the probability of detection against small wall thinning, as well as the false positive rate.

A fabrication of superhydrophobic Perfluoroalkoxy Alkane (PFA) coatings on stainless steel surfaces by cold-spray technique has been demonstrated in this work. The in-situ supersonic impact deposition and consolidation of finely divided 20–40 μm powder material yielded hydrophobic thin coatings of PFA which exhibited contact angles of 125° but high roll off angles of 60°. The deposition efficiencies were less than 0.5%, coating was mechanically very fragile and non-uniform. However, the cold-spray deposition efficiency was subsequently increased to almost 15% by performing simple modification of particle surface morphology by introducing organosilane coated nanoceramic layers on the PFA particles and by laser texturing the stainless steel substrate surfaces to form mountain-valley micro-structures. The nanoceramic interlayers formed bridge bonds at the particle-particle interface and laser texturing achieved efficient coating-substrate interlock. The improved coatings exhibited super-hydrophobic character with 160° contact angle and 6° roll-off angle. The superhydrophobicity was seen to be as a result of micro-/nano-structured surface consisting of papillae like structures capped by a layer of hydrophobic nanoceramic. The coating also exhibited excellent water repellency.

International audience; A model of structured Magneto-rheological Elastomer made of a soft matrix filled by magnetic particles was studied for energy harvesting, in pure shear condition. The particles were supposed to be aligned in a chain along which the magnetic field is applied and considering a shear strain applied in a plane perpendicularly to the chain. As the strain is applied and assuming the deformation is homogeneous and the particles remain aligned, both of the axis of their alignment and inter-distance between particles change, affecting their magnetic state. The aim of this work is to evaluate how far the magnetic induction variation induced by mechanical solicitation can be converted into electric signal. We firstly analyzed the magnetic susceptibility of a particle in the chain, and then derived an analytical expression for the composite permeability as a function of shear strain. FEM simulations taking into account the particle magnetic saturation was also performed to estimate the optimal conditions (magnetic field values, shear amplitude, etc.) maximizing the energy conversion potentials.

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International audience; As an alternative to thermoelectric generators, heat engines show great interest thanks to their ability to convert temperature spatial gradient into time-domain temperature variations or vibrations. To this end, MultiPhysic Memory Alloys (MPMAs), combining shape memory characteristics with ferromagnetic properties, provide significant attractive characteristics such as sharp transition with reduced hysteresis as well as magnetic properties enabled by heating, thus allowing easier device development and implementation. In this study, we report the development of a heat engine for small-scale energy harvesting where the MPMA transfers its heat to a pyroelectric element that provides thermal to electrical energy conversion, yielding a more direct energy conversion path compared to conventional electromechanical heat engines. Furthermore, thermally decoupling the pyroelectric element from the MPMA allows a faster cooling of the latter, accounting for higher variation frequency. Compared to the use of electromagnetic transduction through a coil attached to the moving MPMA, this approach is shown to provide 3 to 9 times more power density (according to considered volume), with theoretical potential gains from 8 to 25 with the use of nonlinear electrical interfaces.

International audience; Nondestructive testing (NDT) techniques are used to evaluate the material degradation of ferromagnetic materials, for example, in sensitive environments, such as thermal power plants, where the materials are subjected to creep damage. There is no consensus on the use of an electromagnetic NDT technique to characterize the evolution of creep damage in high-chromium ferritic steels. In this work, an overview and comparison of three different electromagnetic NDT techniques that were applied to high-chromium steels is provided to understand creep evolution in terms of microstructural changes, such as precipitation, dislocation and grain size. To quantify the empirical measurements, a modelling technique was proposed for each applied method. The model parameters were optimized for each NDT technique and tested material. Depending on the model parameters, the accuracy of the parameter determination depends strongly on the NDT technique, which indicates its correlation with the microstructural information.

International audience; Numerous models have been developed in the literature to simulate the thermomechanical behavior of amorphous polymer at large strain. These models generally show a good agreement with experimental results when the material is submitted to uniaxial loadings (tension or compression) or in case of shear loadings. However, this agreement is highly degraded when they are used in the case of combined load cases. A generalization of these models to more complex loads is scarce. In particular, models that are identified in tension or compression often overestimate the response in shear. One difficulty lies in the fact that 3D models must aggregate different physical modeling, described with different kinematics. This requires the use of transport operators complex to manipulate. In this paper, we propose a mechanical model for large strains, generalized in 3D, and precisely introducing the adequate transport operators in order to obtain an exact kinematic. The stress strain duality is validated in the writing of the power of internal forces. This generalized model is applied in the case of a polycarbonate amorphous polymers. The simulation results in tension/compression and shear are compared with the classical modeling and experimental results from the literature. The results highly improve the numerical predictions of the mechanical response of amorphous polymers submitted to any load case.

Materials composed of metals and plastic composites joined through adhesive bonding are being increasingly used. However, debonding of such materials may occur during manufacture or use. Non-destructive testing of adhesive bonding structures is required to evaluate their debonding. Herein, electromagnetic pulse-induced acoustic testing (EPAT) was used to detect debonding at the adhesive joint in plastic composite/metal specimens. EPAT uses a pulsed excitation current to generate guided waves in a specimen to detect debonding without contact, which makes it suitable for testing from the plastic composite side. Simulations were performed to analyze acrylic/aluminum (Al) and carbon fiber-reinforced plastic (CFRP)/Al specimens. The results showed that the Lorentz force in the z direction was the dominant mechanism in the generation of guided waves, and mainly the A0-mode Lamb wave was excited. The simulation and experimental results revealed that for specimens where the mechanical parameters of the plastic composite layer differed greatly from those of the metal, such as the acrylic/Al specimen, debonding could only be detected directly above debonding. Therefore, it is necessary to evaluate the debonding position by scanning the receiver sensor. Conversely, for specimens with reasonably similar mechanical parameters of the plastic composite and metal layers, like the CFRP/Al specimen, the debonding position could be evaluated by scanning the receiver sensor or excitation coil.

The frequency dependence of ferromagnetic hysteresis and the related core losses is still an open question. From scaling relations up to space discretized and simultaneous contributions resolutions, different levels of accuracy in the estimation of these losses can be reached. Below a given frequency known as the quasi-static threshold, it is well admitted that the hysteresis cycle remains unchanged. A precise evaluation of this threshold is fundamental to simulate and evaluate precisely the magnetization behaviors under higher frequencies. But this estimation is complex, especially through the unique observation of the hysteresis cycles and because of instrumentation limitations. In this manuscript, we propose an alternative and simple method to precisely refine this threshold's estimation. By using an alternative magnetic signature known as the magnetic incremental permeability butterfly loop ( μ IP _ ( H ) ), improvements are proposed in observing the very low-frequency magnetization behaviors and assessing the quasi-static threshold. This work constitutes a leap forward in understanding the magnetic low-frequency behaviors of laminated electric steel sheets.

International audience; Magneto Rheological Elastomers (MREs) are composite materials based on an elastomer filled by magnetic particles. Anisotropic MRE can be easily manufactured by curing the material under homogeneous magnetic field which creates column of particles. The magnetic and elastic properties are actually coupled making these MREs suitable for energy conversion. From these remarkable properties, an energy harvesting device is considered through the application of a DC bias magnetic induction on two MREs as a metal piece is applying an AC shear strain on them. Such strain therefore changes the permeabilities of the elastomers, hence generating an AC magnetic induction which can be converted into AC electrical signal with the help of a coil. The device is simulated with a Finite Element Method software to examine the effect of the MRE parameters, the DC bias magnetic induction and applied shear strain (amplitude and frequency) on the resulting electrical signal.

Magnetism has been used for years as a subsidiary method to identify the level of mechanical residual stress through ferromagnetic steels. It is admitted that residual stress strongly modifies the magnetic behavior and consequently the monitored magnetic signatures. However, some of them like the Eddy Current Magnetic Signature (EC-MS) happen to be especially sensitive. EC-MS exhibits drastic changes, strong enough to predict and anticipate the presence of elastic or plastic deformations. The EC-MS signature is obtained by plotting the imaginary part versus the real part of an Eddy current probe impedance, controlling locally a tested sample under the influence of a slowly varying high amplitude magnetic excitation. The superimposition of the weak amplitude, high-frequency magnetic excitation of the Eddy current probe to the quasi-static contribution creates minor hysteresis loop situations where the reversible magnetic contribution is the main provider. EC-MS is, therefore, an exceptional way to observe and characterize this reversible contribution and this over different average magnetic states. This contribution tends to be particularly sensitive to residual stresses and strains, and so is EC-MS. In this article, the Jiles-Atherton-Sablik theory and an improved Dodd and Deeds analytical solution for the simulation of a pancake-type Eddy current coil are combined to simulate EC-MS. From the simulation results, we illustrate and understand why EC-MS is so sensitive to residual stress. Eventually, we justify this method as probably the most indicated magnetic method for the control and evaluation of residual stresses through structural and construction steels.

The tribo electrochemical behavior of 2205 duplex stainless steel had been studied under acidic and neutral solutions with control of the dissolved dioxygen. The study focused on the oxide film formation using a galvanic technique approach implemented in a tribometer. Higher wear rates were measured in low pH and aerated solution. In low O2 concentration, a wear reduction was observed for each pH. Analysis of the passivation transients showed the pH influence on the oxide growth mechanism, irrespective of the O2 level. Temporal analysis of the transients confirmed the faster passivation of the wear track in acidic solution. In a controlled O2 environment, the nucleation and the oxide growth were slow down, irrespective of pH. The degradation rate was then correlated to the passivation kinetic and the aging of the passive film.

International audience; In large vascular networks with small vessels, the low resolution of medical images causes the segmentation algorithms to fail. Simplified models based on the vessel centerline are convenient to represent complex networks, but are associated with a loss of information. In this work, we propose a pipeline which overcomes the limitations of manually extracted centerlines (low sampling, noise) to reconstruct an anatomically accurate surface or volume mesh suitable for numerical simulation.

This paper describes the detectability of eddy current testing (ECT) using directional eddy current for detection of in-plane fibre waviness in unidirectional carbon fibre reinforced plastic (CFRP) laminate. Three different types of probes, such as circular driving, symmetrical driving and uniform driving probe, were proposed, and the waviness angle was extracted from the contour map of the ECT signal by applying a Canny filter and a Hough transform. By comparing both the waviness angle estimated by ECT and that obtained by an X-ray CT image, the standard deviation (precision) and root mean square error (accuracy) were evaluated to discuss the detectability of these probes. The directional uniform driving probe shows the best detectability and can detect fibre waviness with a waviness angle of more than 2° in unidirectional CFRP. The probe shows a root mean square error of 1.90° and a standard deviation of 4.49° between the actual waviness angle and the angle estimated by ECT. This article is part of the theme issue ‘Advanced electromagnetic non-destructive evaluation and smart monitoring’.

Cold spray coatings elaboration requires optimization of numerous parameters in order to reach the best coatings' performances. A systematic approach can be avoided by using an experimental design. A Doehlert uniform shell design was applied in this work to Zn cold sprayed coating. Coatings were produced on steel substrates to provide high corrosion resistant layers. N2 temperature and gas pressures varied from 200 °C to 320 °C and from 2.0 MPa to 3.0 MPa, respectively. Performance maps were plotted for two descriptors: (i) the interfacial porosity volume (substrate coating interface defects), (ii) coating thickness (i.e., coating durability), and validated with the polarization resistance (i.e., corrosion resistance). Results reported three set of optimized temperature and gas pressure values according to the descriptor. Two optimized protection modes can be obtained: a sacrificial mode from heterogeneities in the coating (290 °C and 3.0 MPa), and a barrier protection mode from homogeneous and dense coatings (320 °C and 2.5 MPa). Mechanism of corrosion has been investigated.

International audience; Extending the concept of Shape Memory Alloys (SMAs), MultiPhysic Memory Alloys (MPMAs) based on Heusler compounds show remarkable properties in terms of multiphysic transitions coupling thermal, structural and magnetic domains. Such characteristics thus unveil new application potentials in the field of actuation or energy harvesting for instance. In particular, one of the most notable features of such materials lies in the presence of a magnetic response in a particular temperature range. In order to further investigate the origin of such characteristics, this study aims at providing qualitative and quantitative theoretical insights for shaping potential future material developments and tailoring, along with experimental investigations supporting the proposed theoretical framework. Such a development is done by considering that the unique MPMA behavior originates from the combination of a first-order hysteretic structural transition between martensitic and austenite phase with a ferromagnetic behavior of the austenite phase. Comparison of such an approach with experimental magnetic property measurements of a Heusler Nickel-Cobalt-Manganese-Indium alloy shows a good ability to predict the low-field magnetic response, highlighting the main involved parameters for further developments.

International audience; Recent works demonstrated the abilities of magneto rheological elastomers (MREs) for mechanical to electrical energy conversion. This class of materials consists of composites composed of a soft elastic matrix filled by ferromagnetic particles. In this work we focus primarily on anisotropic MREs featuring particles that are non-homogenously dispersed in the matrix but form of chains of particles. Such anisotropic MRE are good candidates for energy conversion and harvesting purpose because of the coupling between high magnetization of the soft ferromagnetic particles and low elastic modulus of the matrix; thus, the anisotropic MREs can convert a mechanical cyclic deformation into electric signal. In the framework of magnifying the conversion capabilities of such materials, this study reports the investigation of different filling factors of particles, submitted to various magnetic excitations and amplitudes of mechanical deformation. The multiscale analysis provided by this work, from local effect to global characterization, shows that optimal conditions depend on intrinsic material parameters (e.g., filling factor) as well as external conditions (mainly bias magnetic flux density and applied mechanical solicitation).

Coronary artery bypass grafts (CABGs), including saphenous vein grafts (SVGs) or left internal mammary artery (LIMA) grafts, are recently applied to treat coronary artery aneurysm (CAA). Surgical outcomes are considered to be related to surgical strategies (types of the bypass graft and whether CAA ligated or not) and the size of the CAA (usually characterized by diameter). However, the understanding of the relationship between the surgical outcomes and the abovementioned factors is limited. Previous studies related to CABG treatments have shown hemodynamic studies could help evaluate surgical outcomes through graft mass flow rate, wall shear stress (WSS), and oscillatory shear index (OSI). It is believed that the hemodynamic study of applying CABGs to CAA, which is not studied yet, could help us understand the different CABG surgeries. The aim of the study was to evaluate the hemodynamic differences among different surgical methods. To do this, eight three-dimensional models were constructed, representing application of SVGs and LIMA grafts to CAAs (whether ligated or not) with diameters two, three, and five times the normal diameter, to perform computational fluid dynamics (CFD) simulation. The lumped-parameter model (LPM) was coupled to the boundary of the 3D models which increase the complexity of the simulation, but it can ensure the stability of the simulation boundary conditions. The results show that SVG (no matter whether ligated or not) hemodynamic characteristics are positive, with an average high graft mass flow rate of 70 ml/min, an average WSS of 0.479 Pa, and a low OSI of 0.001. LIMA with CAA ligation has the same characteristics with higher WSS (average 1.701 Pa). The hemodynamic characteristics of LIMA without CAA ligation are negative, including high reverse mass flow rate and high OSI (0.367). The results indicate that the surgical outcomes of LIMA with CAA ligation are likely to be the best among these models. The surgical outcomes of LIMA without CAA ligation seem to be undesirable due to the high reverse mass flow and high OSI. The CAA diameter may not have a significant effect on surgical outcomes.

Two-dimensional triangulated surface models for membranes and their three-dimensional (3D) extensions are proposed and studied to understand the strain-induced crystallization (SIC) of rubbers. It is well known that SIC is an origin of stress relaxation, which appears as a plateau in the intermediate strain region of stress&ndash, strain curves. However, this SIC is very hard to implement in models because SIC is directly connected to a solid state, which is mechanically very different from the amorphous state. In this paper, we show that the crystalline state can be quite simply implemented in the Gaussian elastic bond model, which is a straightforward extension of the Gaussian chain model for polymers, by replacing bonds with rigid bodies or eliminating bonds. We find that the results of Monte Carlo simulations for stress&ndash, strain curves are in good agreement with the reported experimental data of large strains of up to 1200%. This approach allows us to intuitively understand the stress relaxation caused by SIC.

Induced contraction of the suprahyoid muscles via magnetic stimulation is considered to be effective for the rehabilitation of dysphagia. In our previous study, a magnetic stimulation coil with a U-shaped core for stimulating the suprahyoid muscles was developed based on the results of numerical analysis using a simplified human head model. It was confirmed that magnetic stimulation by the coil causes large contraction of the muscles. However, the human head has a complex structure that includes bone structures through which current cannot easily pass. To accurately predict the current density distribution induced by magnetic stimulation, a model that accurately describes the human head is required for numerical analysis. Therefore, in this study, numerical analysis using the finite element method with a human head model that includes the bone structure obtained from computed tomography scans was performed. The results for the model with bone structure show that the coil with a U-shaped core can stimulate the motor points of the suprahyoid muscles in the middle of the submental region. When compared with the current density observed in a model without the bone structure, that in the model with the bone structure was reduced by 29% at a point 20 mm below the mandibular surface. It is thus necessary to perform a numerical analysis using a model with the bone structure to obtain accurate analysis results.

The clinical treatment planning of coronary heart disease requires hemodynamic parameters to provide proper guidance. Computational fluid dynamics (CFD) is gradually used in the simulation of cardiovascular hemodynamics. However, for the patient-specific model, the complex operation and high computational cost of CFD hinder its clinical application. To deal with these problems, we develop cardiovascular hemodynamic point datasets and a dual sampling channel deep learning network, which can analyze and reproduce the relationship between the cardiovascular geometry and internal hemodynamics. The statistical analysis shows that the hemodynamic prediction results of deep learning are in agreement with the conventional CFD method, but the calculation time is reduced 600-fold. In terms of over 2 million nodes, prediction accuracy of around 90%, computational efficiency to predict cardiovascular hemodynamics within 1 second, and universality for evaluating complex arterial system, our deep learning method can meet the needs of most situations., Anzai et al. propose a deep learning approach to estimate the 3D hemodynamics of complex aorta-coronary artery geometry in the context of coronary artery bypass surgery. Their method reduces the calculation time 600-fold, while allowing high resolution and similar accuracy as traditional computational fluid dynamics (CFD) method.