Analytical electron tomography mapping of the SiC pore oxidation at the nanoscale

Silicon carbide is a ceramic material that has been widely studied because of its potential applications, ranging from electronics to heterogeneous catalysis. Recently, a new type of SiC materials with a medium specific surface area and thermal conductivity, called β-SiC, has attracted overgrowing interest as a new class of catalyst support in several catalytic reactions. A primary electron tomography study, performed in usual mode, has revealed a dual surface structure defined by two types of porosities made of networks of connected channels with sizes larger than 50 nm and ink-bottled pores with sizes spanning from 4 to 50 nm. Depending on the solvent nature, metal nanoparticles could be selectively deposited inside one of the two porosities, a fact that illustrates a selective wetting titration of the two types of surfaces by different liquids. The explaining hypothesis that has been put forward was that this selectivity against solvents is related to the pore surface oxidation degree of the two types of pores. A new technique of analytical electron tomography, where the series of projections used to reconstruct the volume of an object is recorded in energy filtered mode (EFTEM), has been implemented to map the pore oxidation state and to correlate it with the morphology and the accessibility of the porous network. Applied, for the first time, at a nanoscale resolution, this technique allowed us to obtain 3D elemental maps of different elements present in the analysed porous grains, in particular oxygen; we found thus that the interconnected channel pores are more rapidly oxidized than the ink-bottled ones. Alternatively, our study highlights the great interest of this method that opens the way for obtaining precise information on the chemical composition of a 3D surface at a nanometer scale.     

Robust deformation capture from temporal range data for surface rendering

Imagine an object such as a paper sheet being waved in front of some sensor. Reconstructing the time‐varying 3D shape of the object finds direct applications in computer animation. The goal of this paper is to provide such a deformation capture system for surfaces. It uses temporal range data obtained by sensors such as those based on structured light or stereo. So as to deal with many different kinds of material, we do not make the usual assumption that the object surface has textural information. This rules out those techniques based on detecting and matching keypoints or directly minimizing color discrepancy. The proposed method is based on a planar mesh that is deformed so as to fit each of the range images. We show how to achieve this by minimizing a compound cost function combining several data and regularization terms, needed to make the overall system robust so that it can deal with low quality datasets. Carefully examining the parameter to residual relationship shows that this cost function can be minimized very efficiently by coupling nonlinear least squares methods with sparse matrix operators. Experimental results for challenging datasets coming from different kinds of range sensors are reported. The algorithm is reasonably fast and is shown to be robust to missing and erroneous data points. Copyright © 2008 John Wiley & Sons, Ltd.     

Time-lapse,three-dimensional in situ imaging of ice crystal growth in a colloidal silica suspension

The freezing of colloidal suspensions is encountered in many natural and engineering processes such as the freezing of soils, food engineering and cryobiology. It can also be used as a bio-inspired, versatile and environmentally friendly processing route for porous materials and composites. Yet, it is still a puzzling phenomenon with many unexplained features, owing to the complexity of the system and the space and time scales at which the process should be investigated. This study demonstrates the interest in fast X-ray computed tomography for providing time-lapse, three-dimensional, in situ imaging of ice crystal growth in a colloidal silica suspension. The experimental measurements show that the local increase in colloid concentration does not affect the growth kinetics of the crystals until the colloidal particles become closely packed. For particles much smaller than ice crystals, the concentrated colloidal suspension is equivalent to a simple liquid phase with higher viscosity and a freezing point determined by the concentration of colloidal particles.     

Revue de Introduction a la Psychologie de l'Enfant (Tomes 1, 2 et 3).

Reviews the book, Introduction a la Psychologie de l'Enfant edited by Michel Hurtig and Jean-Adolphe Rondal (1981). The three volumes of this handbooks covers theories of child psychology as presented by numerous authories in the field. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Procedural generation of villages on arbitrary terrains

Although procedural modeling of cities has attracted a lot of attention for the past decade, populating arbitrary landscapes with non-urban settlements remains an open problem. In this work, we focus on the modeling of small, European villages that took benefit of terrain features to settle in safe, sunny or simply convenient places. We introduce a three step procedural generation method. First, an iterative process based on interest maps is used to progressively generate settlement seeds and the roads that connect them. The fact that a new road attracts settlers while a new house often leads to some extension of the road network is taken into account. Then, an anisotropic conquest method is introduced to segment the land into parcels around settlement seeds. Finally, we introduce open shape grammar to generate 3D geometry that adapts to the local slope. We demonstrate the effectiveness of our method by generating different kinds of village on arbitrary terrains, from a mountain hamlet to a fisherman village, and validate through comparison with real data.     

State‐of‐the‐Art Report on Temporal Coherence for Stylized Animations

Non‐photorealistic rendering (NPR) algorithms allow the creation of images in a variety of styles, ranging from line drawing and pen‐and‐ink to oil painting and watercolour. These algorithms provide greater flexibility, control and automation over traditional drawing and painting. Despite significant progress over the past 15 years, the application of NPR to the generation of stylized animations remains an active area of research. The main challenge of computer‐generated stylized animations is to reproduce the look of traditional drawings and paintings while minimizing distracting flickering and sliding artefacts present in hand‐drawn animations. These goals are inherently conflicting and any attempt to address the temporal coherence of stylized animations is a trade‐off. This state‐of‐the‐art report is motivated by the growing number of methods proposed in recent years and the need for a comprehensive analysis of the trade‐offs they propose. We formalize the problem of temporal coherence in terms of goals and compare existing methods accordingly. We propose an analysis for both line and region stylization methods and discuss initial steps towards their perceptual evaluation. The goal of our report is to help uninformed readers to choose the method that best suits their needs, as well as motivate further research to address the limitations of existing methods.     

Monocular Template-based Reconstruction of Inextensible Surfaces

We present a monocular 3D reconstruction algorithm for inextensible deformable surfaces. It uses point correspondences between a single image of the deformed surface taken by a camera with known intrinsic parameters and a template. The main assumption we make is that the surface shape as seen in the template is known. Since the surface is inextensible, its deformations are isometric to the template. We exploit the distance preservation constraints to recover the 3D surface shape as seen in the image. Though the distance preservation constraints have already been investigated in the literature, we propose a new way to handle them. Spatial smoothness priors are easily incorporated, as well as temporal smoothness priors in the case of reconstruction from a video. The reconstruction can be used for 3D augmented reality purposes thanks to a fast implementation. We report results on synthetic and real data. Some of them are compared to stereo-based 3D reconstructions to demonstrate the efficiency of our method.     

A locally anisotropic fluid–structure interaction remeshing strategy for thin structures with application to a hinged rigid leaflet

An immersed finite element fluid–structure interaction algorithm with an anisotropic remeshing strategy for thin rigid structures is presented in two dimensions. One specific feature of the algorithm consists of remeshing only the fluid elements that are cut by the solid such that they fit the solid geometry. This approach allows to keep the initial (given) fluid mesh during the entire simulation while remeshing is performed locally. Furthermore, constraints between the fluid and the solid may be directly enforced with both an essential treatment and elements allowing the stress to be discontinuous across the structure. Remeshed elements may be strongly anisotropic. Classical interpolation schemes – inf–sup stable on isotropic meshes – may be unstable on anisotropic ones. We specifically focus on a proper finite element pair choice. As for the time advancing of the fluid–structure interaction solver, we perform a geometrical linearization with a sequential solution of fluid and structure in a backward Euler framework. Using the proposed methodology, we extensively address the motion of a hinged rigid leaflet. Numerical tests demonstrate that some finite element pairs are inf–sup unstable with our algorithm, in particular with a discontinuous pressure. Copyright © 2015 John Wiley & Sons, Ltd.     

Batch distillation of spirits: experimental study and simulation of the behaviour of volatile aroma compounds

This paper focuses on the behaviour of volatile compounds during batch distillation of wine or low wine, in traditional Charentais copper stills, heated with a direct open flame at laboratory (600 L) and industrial (2500 L) scale. Sixty‐nine volatile compounds plus ethanol were analysed during the low wine distillation in the 600 L alembic still. Forty‐four were quantified and classified according to their concentration profile in the distillate over time and compared with previous studies. Based on the online recording of volume flow, density and temperature of the distillate with a Coriolis flowmeter, distillation was simulated with ProSim® BatchColumn software. Twenty‐six volatile compounds were taken into account, using the coefficients of the ‘Non‐Random Two Liquids’ model. The concentration profiles of 18 compounds were accurately represented, with slight differences in the maximum concentration for seven species together with a single compound that was poorly represented. The distribution of the volatile compounds in the four distillate fractions (heads, heart, seconds and tails) was well estimated by simulation. Finally, data from wine and low wine distillations in the large‐scale alembic still (2500 L) were correctly simulated, suggesting that it was possible to adjust the simulation parameters with the Coriolis flowmeter recording and represent the concentration profiles of most of the quantifiable volatile compounds. © 2019 The Institute of Brewing & Distilling