Ontology-based Land Degradation Assessment from Satellite Images

International audienceIn this paper, we introduce the idea of documenting operational chains for land degradation assessment using ontologies. We believe that this will help end-users in better understanding the land degradation characteristics and evaluate the results of the assessment process. Since the application domain is wide, various operational chains for land degradation assessment and their associated documentation exist, according to different options. This parameterization causes the development of different ontologies, which, nonetheless are to a certain extent linked because of the common software components of the corresponding operational chains. We therefore propose a hierarchical structure of these ontologies; so that several requirements such as understanding of expert knowledge interconnections and application domain variety, documentation, assimilation of new expert knowledge, and reusability of software components become feasible

Growth of self-organized cobalt nanostructures on Au(111) vicinal surfaces

We studied the growth of cobalt on Au(lll) vicinal surfaces in the submonolayer range. We found that the presence of a surface reconstruction leads to interesting self-organized nanostructures, such as very regular arrays of clusters or nanowires. We show that the use of a vicinal substrate strongly improves their long-range order properties. These results, together with the periodic faceting behaviour of gold vicinal surfaces, open the way to fabricate cobalt nanostructures or ultrathin films with original magnetic properties. (C) 2000 Elsevier Science B.V. All rights reserved

Reconstruction, step edges and self-organization on the Au(111) surface

5th International Conference on Atomic Controlled Surfaces, Interfaces and Nanostructures (ACSIN 5), UNIV AIX MARSEILLE, AIX PROVENCE, FRANCE, JUL 06-09, 1999It has been shown recently that vicinal surfaces of Au(lll) are unstable towards faceting. The period of the faceted morphology is very sensitive to the step edge atomic structure and can vary from about 10 up to 200 nm. We report a scanning tunneling microscopy (STM) study demonstrating that the famous 22 x root 3 reconstruction of the Au(lll) surface interacts differently with both types of close-packed step edges that can be found on a (111) surface: the lines of discommensuration cross (111) step edges and are stopped by (100) ones. This observation could be essential in order to explain the drastic change in the faceted morphology of Au(111) vicinal surfaces with different step edges. Furthermore, it is promising in the way of realizing original nanostructures on these vicinal surfaces. Preliminary results are shown. (C) 2000 Elsevier Science B.V. All rights reserved

Interaction between steps and reconstruction on Au(111)

Due to its famous 22x root 3 reconstruction, the Au(lll) surface can he considered as an ideal substrate to grow nanostructured arrays of metallic clusters. In this letter, we report a complete investigation of the interaction between this reconstruction and the close-packed steps of the Au(lll) surface. Scanning tunneling microscopy experiments clearly demonstrate that the behaviour of the reconstruction in the vicinity of steps depends drastically on the step microstructure. This result, of particular interest for the managing of new nanostructured substrates, is interpreted in terms of the relative stability of both types of steps

Ontology-based documentation of land degradation assessment from satellite images

International audienceIn this paper, we introduce the idea of documenting operational chains for land degradation assessment using ontologies. We believe that this process will help end users better understand the application domain characteristics and evaluate the results of the assessment process. Since the application domain is wide, various operational chains for land degradation assessment and their associated documentation exist, according to different options. This parameterization process causes the development of different ontologies, which nonetheless are, to a certain extent, linked because of the common software components of the corresponding operational chains. We therefore propose a hierarchical structure of these ontologies; so that several requirements such as understanding of expert knowledge interconnections and of application domain variety, documentation and assimilation of new expert knowledge, and reusability of software components become feasible

Morphology of Au(1,1,1) vicinal surfaces studied by grazing incidence X-ray diffraction

6th International Conference on X-ray and Neutron Scattering, LEEWENHORST CONGRESS CTR, NOORDWIJKERHOUT, NETHERLANDS, SEP 12-17, 1999Two gold vicinal surfaces misoriented by 6 degrees, in opposite direction with respect to the (1,1,1) plane, namely the (4,5,5) and the(11,9,9) surfaces have been studied by grazing incidence X-ray diffraction. The main difference between these two surfaces is the step microscopic structure since the (4,5,5) surface presents \1,1,1\ like steps whereas the (11,9,9) surface exposes \1,0,0\ like steps, Two strongly different faceted morphologies are observed in good agreement with Scanning Tunneling Microscopy experiments. Surface reconstruction has also been extensively studied and our results open the way to understand the original faceting properties of gold vicinal surfaces. (C) 2000 Elsevier Science B.V. All rights reserved

HgTe-CdTe superlattices: Experimental and theoretical curves of band gap versus HgTe layer thickness

An experimental curve of room-temperature band gap versus HgTe layer thickness for HgTe-CdTe superlattices is presented for the first time. The room-temperature experimental results are compared to theoretical results determined using the envelope function approximation. Also a few values of the band gap at 2 K are given and compared to theoretical predictions. A good agreement between experiment and theory is found

Data assimilation of satellite images within an oceanographic circulation model

We tackle the problem of coupling a geophysical simulation model with data coming from image processing. It needs to define the image observation space and to design an operator to transform results from the image space to the model space. In this study, we use a shallow-water oceanographic circulation model developed at MHI. We propose a processing chain first based on an image processing step relying on a dedicated motion estimation operator, and then a data assimilation step of the estimated velocity. We illustrate the method on different results without and with assimilation. 1. OBJECTIVES In the framework of numerical forecasting for the evolution of geophysical fluid, we are interested in the assimilation of data coming from images. In order to forecast the behavior of geophysical fluids we need: a forecast model to describe the evolution of a state variabl