Development of a dynamic virtual reality model of the inner ear sensory system as a learning and demonstrating tool

In order to keep track of the position and motion of our body in space, nature has given us a fascinating and very ingenious organ, the inner ear. Each inner ear includes five biological sensors - three angular and two linear accelerometers - which provide the body with the ability to sense angular and linear motion of the head with respect to inertial space. The aim of this paper is to present a dynamic virtual reality model of these sensors. This model, implemented in Matlab/Simulink, simulates the rotary chair testing which is one of the tests carried out during a diagnosis of the vestibular system. High-quality 3D-animations linked to the Simulink model are created using the export of CAD models into Virtual Reality Modeling Language (VRML) files. This virtual environment shows not only the test but also the state of each sensor (excited or inhibited) in real time. Virtual reality is used as a tool of integrated learning of the dynamic behavior of the inner ear using ergonomic paradigm of user interactivity (zoom, rotation, mouse interaction,…). It can be used as a learning and demonstrating tool either in the medicine field - to understand the behavior of the sensors during any kind of motion - or in the aeronautical field to relate the inner ear functioning to some sensory illusions

Damage localization map using electromechanical impedance spectrums and inverse distance weighting interpolation: Experimental validation on thin composite structures

Piezoelectric sensors are widely used for structure health monitoring technique. In particular, electromechanical impedance techniques give simple and low-cost solutions for detecting damage in composite structures. The purpose of the method proposed in this article is to generate a damage localization map based on both indicators computed from electromechanical impedance spectrums and inverse distance weighting interpolation. The weights for the interpolation have a physical sense and are computed according to an exponential law of the measured attenuation of acoustic waves. One of the main advantages of the method, so-called data-driven method, is that only experimental data are used as inputs for our algorithm. It does not rely on any model. The proposed method has been validated on both one-dimensional and two-dimensional composite structures

Smart EMI monitoring of thin composite structures

This paper presents a structural health monitoring (SHM) method for in-situ damage detection and localization in carbon fibre reinforced plates (CFRP). The detection is achieved using the electromechanical impedance (EMI) technique employing piezoelectric transducers as high-frequency modal sensors. Numerical simulations based on the finite element method are carried out so as to simulate more than a hundred damage scenarios. Damage metrics are then used to quantify and detect changes between the electromechanical impedance spectrum of a pristine and damaged structure. The localization process relies on artificial neural networks (ANN) whose inputs are derived from a principal component analysis of the damage metrics. It is shown that the resulting ANN can be used as a tool to predict the in-plane position of a single damage in a laminated composite plate

Smart monitoring of aeronautical composites plates based on electromechanical impedance measurements and artificial neural networks

This paper presents a structural health monitoring (SHM) method for in situ damage detection and localization in carbon fiber reinforced plates (CFRPs). The detection is achieved using the electromechanical impedance (EMI) technique employing piezoelectric transducers as high-frequency modal sensors. Numerical simulations based on the finite element method are carried out so as to simulate more than a hundred damage scenarios. Damage metrics are then used to quantify and detect changes between the electromechanical impedance spectrum of a pristine and damaged structure. The localization process relies on artificial neural networks (ANNs) whose inputs are derived from a principal component analysis of the damage metrics. It is shown that the resulting ANN can be used as a tool to predict the in-plane position of a single damage in a laminated composite plate

Modélisation des assemblages de ballons pressurisés stratosphériques

Long duration super-pressure balloon design and manufacturing is a great challenge for the CNES in scientific ballooning. They are made of 50 µm thick polymer films (PET/PA/PET) which are joined with 23 µm thick adhesive PET bands. To date, during flight missions, a real problem appears: some balloons explode prematurely. This is why this study deals with the mechanical behaviour of the stratospheric pressurized balloons and particularly with the assembly of the constitutive materials. Firstly, a nanoindentation test campaign makes it possible to identify the elastic properties of the materials directly in the assembly at two different temperatures. Then, we simulate a nominal assembly in two approaches: 2D and 3D. More particularly, we present an example concerning a defect of the junction in 3D approach using the submodeling technique. Finally, we use the factorial design method at two levels and finite-element models to study the influence of the various conception parameters on the mechanical behaviour of the assembly

Mapping roadless areas in regionswith contrasting human footprint

In an increasingly human- and road-dominated world, the preservation of functional ecosystems has become highly relevant. While the negative ecological impacts of roads on ecosystems are numerous and well documented, roadless areas have been proposed as proxy for functional ecosystems. However, their potential remains underexplored, partly due to the incomplete mapping of roads. We assessed the accuracy of roadless areas identification using freely available road-data in two regions with contrasting levels of anthropogenic influence: boreal Canada and temperate Central Europe (Poland, Slovakia, Czechia, and Hungary). Within randomly selected circular plots (per region and country), we visually examined the completeness of road mapping using OpenStreetMap 2020 and assessed whether human influences affect mapping quality using four variables. In boreal Canada, roads were completely mapped in 3% of the plots, compared to 40% in Central Europe. Lower Human Footprint Index and road density values were related to greater incompleteness in road mapping. Roadless areas, defined as areas at least 1 km away from any road, covered 85% of the surface in boreal Canada (mean size ± s.d. = 272 ± 12,197 km2), compared to only 0.4% in temperate Central Europe (mean size ± s.d. = 0.6 ± 3.1 km2). By visually interpreting and manually adding unmapped roads in 30 randomly selected roadless areas from each study country, we observed a similar reduction in roadless surface in both Canada and Central Europe (27% vs 28%) when all roads were included. This study highlights the urgent need for improved road mapping techniques to support research on roadless areas as conservation targets and surrogates of functional ecosystems. Roadless areas, OpenStreetMap, Road mapping, Road ecology, Anthropogenic impact, Human footprint index, Human modification index, Travel time to major citiespublishedVersio

Toward a three-dimensional finite-element model of the human inner ear angular accelerometers sensors

The vestibular section of the inner ear is partly comprised of three semicircular canals that detect head angular acceleration. This system is filled with a Newtonian fluid and its functioning pertains on fluid-structure interactions. The aim of the present paper is first to present a two-dimensional model of a single semicircular canal using fluid-structural finiteelements simulations. Second, this two-dimensional model is extended to 3-D space and to the case where the entire set of canals is considered. To achieve this goal, we first develop a two dimensional finite-elements model of a single canal. Using a strong coupling between the fluid flow and the structural displacements and also an Arbitrary Lagrangian Eulerian (ALE) approach for the moving mesh, we analyze displacements of the cupulae and fluid velocity during head rotation. Second, this 2-D model is extended to a three-dimensional case by considering the entire set of canals. Preliminary results showing cupula deformation as well as fluid flow highlight a good correlation with the 2-D model

Numerical modelling of parts distortion and beam supports breakage during selective laser melting (SLM) additive manufacturing

The Selective Laser Melting (SLM) process has been progressively endorsed as an industrial manufacturing technique to produce high value-added components. However, one of the main obstacles to its wide application is the uncertainty regard- ing the successful completion of the manufacturing process. Mechanical stresses are generated and accumulated during the process, which may lead to the parts warping and cracking. Support structures may also detach from the part but it is not certain that these cracks conduct to the manufacturing failure. The process simulations currently available do not consider the cracking of the supports and the ongoing part’s deflection. The aim of this study is to investigate cone supports fracture behaviour comparing the results from a numerical model and the manufacturing of an industrial part. A model using 1D-beam elements to mesh the supports has been developed to consider the damage of the supports, their breakage and the ongoing deflection. Some numerical convergence issues are identified and solutions are proposed. Specific experimental set-ups are developed to characterise the behaviour of the supports individually and as a group. Significant improvements are denoted while injecting the measured characteristics within the model. Some key parameters of the supports damage behaviour are identified. It is shown that the supports mechanical characteristics are significantly different from the parts due to their manufacturing conditions and environment. Also, limitations regarding the characterisation of the supports as well as strong numerical convergence issues brought by multiple supports cracking are discussed

Numerical and mechanical modeling of the inner ear vestibular apparatus

As you read this text, tilt your head left and right. Note then that the text stands still. Now draw a clear line onto the ground, close your eyes and walk over it. You most likely succeeded. The aforementioned facts or abilities are remarkable skills given by a small inner ear organ set, the vestibular system. Usually operating in the background, this structure infrequently comes to the attention of our conscious mind. In this work, three finite element models (in CATIA V5R18 and COMSOL Multiphysics 3.5a environments) are developed to provide a mechanical understanding of this formidable nature’s gift. In these numerical models, a fluid structure interaction modeling is presented to show the system behavior during a horizontal head spin. Finally, a physical augmented scale model is proposed, including the choice of materials and a similitude study

Patterns and correlates of claims for brown bear damage on a continental scale

Wildlife damage to human property threatens human-wildlife coexistence. Conflicts arising from wildlife damage in intensively managed landscapes often undermine conservation efforts, making damage mitigation and compensation of special concern for wildlife conservation. However, the mechanisms underlying the occurrence of damage and claims at large scales are still poorly understood. Here, we investigated the patterns of damage caused by brown bears Ursus arctos and its ecological and socio-economic correlates at a continental scale. We compiled information about compensation schemes across 26 countries in Europe in 2005-2012 and analysed the variation in the number of compensated claims in relation to (i) bear abundance, (ii) forest availability, (iii) human land use, (iv) management practices and (v) indicators of economic wealth. Most European countries have a posteriori compensation schemes based on damage verification, which, in many cases, have operated for more than 30 years. On average, over 3200 claims of bear damage were compensated annually in Europe. The majority of claims were for damage to livestock (59%), distributed throughout the bear range, followed by damage to apiaries (21%) and agriculture (17%), mainly in Mediterranean and eastern European countries. The mean number of compensated claims per bear and year ranged from 0·1 in Estonia to 8·5 in Norway. This variation was not only due to the differences in compensation schemes; damage claims were less numerous in areas with supplementary feeding and with a high proportion of agricultural land. However, observed variation in compensated damage was not related to bear abundance. Synthesis and applications. Compensation schemes, management practices and human land use influence the number of claims for brown bear damage, while bear abundance does not. Policies that ignore this complexity and focus on a single factor, such as bear population size, may not be effective in reducing claims. To be effective, policies should be based on integrative schemes that prioritize damage prevention and make it a condition of payment of compensation that preventive measures are applied. Such integrative schemes should focus mitigation efforts in areas or populations where damage claims are more likely to occur. Similar studies using different species and continents might further improve our understanding of conflicts arising from wildlife damage