Search results for "roughness"
showing 10 items of 216 documents
How and why does willow biochar increase a clay soil water retention capacity?
2018
Addition of biochar into a soil changes its water retention properties by modifying soil textural and structural properties. In addition, internal micrometer-scale porosity that is able to directly store readily plant available water affects soil water retention properties. This study shows how precise knowledge of the internal micrometer-scale pore size distribution of biochar can deepen the understanding of the biochar-water interactions in soils. The micrometer-scale porosity of willow biochar was quantitatively and qualitatively characterized using X-ray tomography, 3D image analysis and Helium ion microscopy. The effect of biochar application on clay soil water retention was studied by…
Impact of very low crop residues cover on wind erosion in the Sahel
2011
International audience; In the Sahel, with average annual precipitation in the order of 500 mm yr− 1, wind erosion occurs mainly on cultivated millet fields whose surfaces are only partially covered by crop residues. The impact of these residues on wind erosion was not clearly established. The objective of this study is thus to quantify the actual amount of crop residues in traditional Sahelian fields and to determine their impacts on wind erosion by reference to a bare surface throughout the seasonal cycle over several years. At the beginning of the year during dry season, Sahelian farmers use to "clean" their fields, i.e. cut and lay flat on the soil surface any millet stalks still standi…
Roughness evaluation of vine leaf by image processing
2013
International audience; The study of leaf surface roughness is very important in the domain of precision spraying. It is one of the parameters that allow to reduce costs and losses of phytosanitary prod- ucts and to improve the spray accuracy. Moreover, the leaf roughness is related to adhesion mechanisms of liquid on a surface. It can be used to define leaf nature surface (hy- drophilic/hydrophobic). The main goal of this study is thus to estimate and to follow the evolution of leaf roughness using image processing and computer vision. The develop- ment and application of computer vision for measurement of surface leaf roughness using artificial neural networks will be described. The syste…
Digital Correlation Method Based on Microgeometrical Texture Patterns for Strain Fields Measurements
2005
International audience; Digital correlation method is widely used in experimental mechanics to obtain the deformation field. Currently this method is applied with digital images of the initial and deformed surface sprayed with black or white painting. Speckle patterns are then captured and the correlation can be made with high 0.01 pixel accuracy in 2D-cases. In three-dimensions, the stereo-correlation can be used with a lower accuracy. The work presented in this paper, is a first approach based on the use of a 3D laser scanner in the objective of three-dimensional strain field measurement. The digital speckle patterns are not given by gray level but from the micro-geometrical surface textu…
Study and Comparison of Surface Roughness Measurements
2014
Journées du Groupe de Travail en Modélisation Géométrique (GTMG'14), Lyon; This survey paper focus on recent researches whose goal is to optimize treatments on 3D meshes, thanks to a study of their surface features, and more precisely their roughness and saliency. Applications like watermarking or lossy compression can benefit from a precise roughness detection, to better hide the watermarks or quantize coarsely these areas, without altering visually the shape. Despite investigations on scale dependence leading to multi-scale approaches, an accurate roughness or pattern characterization is still lacking, but challenging for those treatments. We think there is still room for investigations t…
Morphological and chemical dynamics upon electrochemical cyclic sodiation of electrochromic tungsten oxide coatings extracted by in situ ellipsometry.
2020
The sodiation–desodiation process of sputtered amorphous electrochromic tungsten oxide coatings in an aqueous-based medium was simultaneously monitored over 99 cycles by cyclic voltammetry and in situ spectroscopic ellipsometry. This allowed extracting the evolution of optical and geometrical parameters upon cycling. The resulting electrochemical coloring-bleaching process was dynamically fitted in the 1.8–2.8 eV optical range with a four-phase model including a constrained spline parametrization of the dielectric function. This allows real time access to thickness, surface roughness, and dielectric function of N a x W O 3 . The temporal evolution of the latter in the fully colored state wa…
Measuring vine leaf roughness by image processing
2013
International audience; In precision spraying, spray application efficiency depends on the pesticide application method, the phytosanitary product as well as the leaf surface properties. For environmental and economic reasons, the global trend is to reduce the pesticide application rate of the few approved active substances. Under these constraints, one of the challenges is to improve the efficiency of pesticide application. Different parameters can influence on pesticide application as nozzle types, liquid viscosity and leaf surface. Specific models have been developed showing that the predominant factor for the leaf is the leaf roughness, because it is related on adhesion mechanisms of li…
Leaf surface roughness characterization by image processing
2013
International audience
3 D digitization of specular metallic surfaces by means of infrared imaging
2012
For the past twenty years, the need for three-dimensional digitization of manufactured objects has increased significantly and consequently, many experimental techniques and commercial solutions have been proposed. However, difficulties remain for the acquisition of optically non cooperative surfaces, such as transparent or specular ones. Since the working principle of conventional scanners is based on the acquisition of the diffuse part of the reflection, transparency and specular reflections may cause outliers. To address highly reflective metallic surfaces, we propose the extension of a non conventional technique that was originally dedicated to glass objects, called “Scanning from Heati…
Coupling two radar backscattering models to assess soil roughness and surface water content at farm scale
2013
Remote sensing techniques are useful for agro-hydrological monitoring at the farm scale because the availability of spatially and temporally distributed data improves agricultural models for irrigation and crop yield optimization under water scarcity conditions. This research focuses on the surface water content retrieval using active microwave data. Two semi-empirical models were chosen as these showed the best performances in simulating cross and co-polarized backscatter. Thus, these models were coupled to obtain reliable assessments of both soil water content and soil roughness. The use of the coupled model enables one to avoid using roughness measured in situ. Remote sensing images and …