Integrating Perceptual Signal Features within a Multi-facetted Conceptual Model for Automatic Image Retrieval

International audienceThe majority of the content-based image retrieval (CBIR) systems are restricted to the representation of signal aspects, e.g. color, texture... without explicitly considering the semantic content of images. According to these approaches a sun, for example, is represented by an orange or yellow circle, but not by the term "sun". The signal-oriented solutions are fully automatic, and thus easily usable on substantial amounts of data, but they do not fill the existing gap between the extracted low-level features and semantic descriptions. This obviously penalizes qualitative and quantitative performances in terms of recall and precision, and therefore users' satisfaction. Another class of methods, which were tested within the framework of the Fermi-GC project, consisted in modeling the content of images following a sharp process of human-assisted indexing. This approach, based on an elaborate model of representation (the conceptual graph formalism) provides satisfactory results during the retrieval phase but is not easily usable on large collections of images because of the necessary human intervention required for indexing. The contribution of this paper is twofold: in order to achieve more efficiency as far as user interaction is concerned, we propose to highlight a bond between these two classes of image retrieval systems and integrate signal and semantic features within a unified conceptual framework. Then, as opposed to state-of-the-art relevance feedback systems dealing with this integration, we propose a representation formalism supporting this integration which allows us to specify a rich query language combining both semantic and signal characterizations. We will validate our approach through quantitative (recall-precision curves) evaluations

Efecto de la presión de confinamiento y el método de deposición sobre la respuesta de corte no drenada de arena de densidad media

This study examines the effects of the confining pressure and sample preparation method on the shearing behavior shown by sand from the Chlef River (Algeria). Undrained monotonic triaxial compression tests were performed on samples with an initial relative density of 50% at initial confining pressures of 50 to 200 kPa. Samples were prepared using two depositional methods: dry funnel pluviation and wet deposition. Our results reveal marked differences in the undrained shearing responses produced under identical conditions of density and stress and therefore determined by the soil fabric. Thus, at low confining pressures, samples prepared by the wet deposition method showed complete static liquefaction (zero effective confining pressure and zero stress difference). For both sample types, as confining pressures increased, effective stress paths exhibited increasing resistance to liquefaction indicated by increasing dilatant tendencies.En este trabajo se han estudiado los efectos de la presión de confinamiento y los métodos de preparación de muestras sobre el comportamiento de rotura de arena Chlef. Los resultados de las pruebas sin escurrir monótona de compresión triaxial realizadas en muestras con una densidad relativa inicial del 50% y presiones de confinamiento inicial variaron desde 50 hasta 200 kPa. Las muestras fueron preparadas por dos métodos de deposición seca con embudo de pluviacion y deposición húmeda. Se encontró que existía una marcada diferencia en el comportamiento sin escurrir a pesar de que las condiciones de la densidad y el estrés eran idénticas. La conclusión fue que la estructura del suelo fue la responsable de este resultado. Los resultados también indicaron que a baja presión de confinamiento, las muestras preparadas mediante un método de deposición húmedo, completan la licuefacción estática (ninguna presión de confinamiento efectiva y ninguna diferencia de estress). Los resultados indicaron también que a bajas presiones de confinamiento, los especímenes reconstituida por el método de deposición húmeda expuesto licuefacción estática completa (cero de la presión efectiva de confinamiento y cero diferencia de estrés). Como las presiones de confinamiento se incrementaron, las trayectorias de tensiones efectivas aumentaron la resistencia a la licuefacción, mostrando aumento de la tendencia dilatante