Designing a Belief Function-Based Accessibility Indicator to Improve Web Browsing for Disabled People

The purpose of this study is to provide an accessibility measure of web-pages, in order to draw disabled users to the pages that have been designed to be ac-cessible to them. Our approach is based on the theory of belief functions, using data which are supplied by reports produced by automatic web content assessors that test the validity of criteria defined by the WCAG 2.0 guidelines proposed by the World Wide Web Consortium (W3C) organization. These tools detect errors with gradual degrees of certainty and their results do not always converge. For these reasons, to fuse information coming from the reports, we choose to use an information fusion framework which can take into account the uncertainty and imprecision of infor-mation as well as divergences between sources. Our accessibility indicator covers four categories of deficiencies. To validate the theoretical approach in this context, we propose an evaluation completed on a corpus of 100 most visited French news websites, and 2 evaluation tools. The results obtained illustrate the interest of our accessibility indicator

Be analysis of bottom sediments in dynamic fluid-structure interaction problems

Sediment materials play an important role on the dynamic response of large structures where fluid-soil-structure interaction is relevant and materials of that kind are present. Dam-reservoir systems and harbor structures are examples of civil engineering constructions where those effects are significant. In those cases the dynamic response is determined by hydrodynamic water pressure, which depends on the absorption effects of bottom sediments. Sediments of very different mechanical properties may exist on the bottom. A three-dimensional BE model for the analysis of sediment effects on dynamic response of those structures is presented in this paper. One of the most extended models for sediment materials corresponds to Biot’s fluid-filled poroelastic solid. The BE formulation for dynamics of poroelastic solids is reviewed including a weighted residual formulation more general and concise than those previously existing in literature. Systems consisting of water, other pressure wave propagating materials, viscoelastic solids and fluid-filled poroelastic zones, are studied. Coupling conditions at interfaces are taken into account in a rigorous way. A simple geometry coupled problem is first studied to asses the effects of sediments on its dynamic response and to determine the influence of parameters such as sediment depth, consolidation, compressibility and permeability. A fully 3-D arch dam-reservoir-foundation system where sediments and radiation damping play an important role is also studied in this paper. Obtained results show the importance of a realistic representation of sediments and the influence of their consolidation degree, compressibility and permeability on the system dynamic response.Ministerio de Ciencia y Tecnología BIA2004-03955-C02-01/0

A 3-D boundary element model for the dynamic analysis of arch dams with porous sediments

A three-dimensional boundary element technique for dynamic analysis of arch dams including dynamic interaction and sediments on the bottom of the reservoir is presented. The dam and the foundation rock are assumed to be viscoelastic domains with linear behaviour. The water is assumed to be compressible and the sediment is considered as a two-phase poroelastic material according to Biot's theory. The four domains (dam, foundation rock, water and bottom sediments) are discretized and the interaction between them is rigorously represented. The effects of sediments on the dynamic response of arch dams are evaluated for rigid and compliant foundation. Upstream, vertical and cross-stream excitation are considered. The influence of the degree of saturation of the sediment is analysed. Other modelling of the sediment as a single-phase scalar medium are considered in order to reduce the degrees of freedom of the system.Ministerio de Ciencia y Tecnología PB96-1322-C03-0

Testicular development in migrant and spawning bluefin tuna (Thunnus thynnus (L.)) from the eastern Atlantic and Mediterranean

Testis histological structure was studied in bluefin tuna (Thunnus thynnus) from the eastern Atlantic and Mediterranean during the reproductive season (from late April to early June). Testicular maturation was investigated by comparing samples from bluefin tuna caught on their eastward reproductive migration off Barbate (Strait of Gibraltar area) with samples of bluefin tuna fished in spawning grounds around the Balearic Islands. Histological evaluations of cross sections showed that the testis consists of two structurally different regions, an outer proliferative region where germ cells develop synchronously in cysts, and a central region made up of a well-developed system of ducts that convey the spermatozoa produced in the proliferative region to the main sperm duct. Ultrastructural features of the different stages of the male germ cell line are very similar to those described in other teleost species. The bluefin tuna testis is of the unrestricted spermatogonial testicular type, where primary spermatogonia are present all along the germinative portion of the lobules. All stages of spermatogenesis were present in the gonad tissue of migrant and spawning bluefin tuna, although spermatids were more abundant in spawning fish. The testis size was found to increase by a factor of four (on average) during migration to the Mediterranean spawning grounds, whereas the fat bodies (mesenteric lipid stores associated with the gonads) became reduced to half their weight, and the liver mass did not change significantly with sexual maturation. Linear regression analysis of the pooled data of migrant and spawning bluefin tuna revealed a significant negative correlation between the gonad index (IG) and the fat tissue index (IF), and a weaker positive correlation between the gonad index (IG) and the liver index (IL). Our analyses indicate that the liver does not play a significant role in the storage of lipids and that mesenteric lipid reserves constitute an important energy source for gametogenesis in bluefin tuna

El uso del método de los elementos de contorno en el cálculo dinámico de problemas axilsimétricos

VII CONGRESO NACIONAL DE INGENIERIA MECANICA En VALENCIAThe objetive of this paper is to show the flexibility of he B.E.M. for calculation of the dynamic impedances of axisymmetric rigid foundations in homogeneuos and layered media. Beside introducing the below formulation the method is applied to the case of hemispherical foundation in order to show certain aspects of its behavior and the influence of different factors upen dynamical impedances such as internal soil damping and relative rigidity of the base in the case of two l ayered media.El objetivo de esta comunicación es mostrar la flexibilidad del Método de los Elementos de Contorno para abordar el cálculo de las impedancias dinámicas de las cimentaciones rígidas con simetría de revolución embebidas en medios homogéneos y estratificados. Además de presentar la formulación desarrollada, el método se aplica al caso de cimentaciones semiesféricas poniéndose de manifiesto ciertos aspectos de su comportamiento y la influencia de los diferentes factores sobre las impedancias dinámicas tales como: índice de amortiguamiento y rigidez relativa de la base para el caso de terrenos estratificados de tipo bicapa. Los resultados obtenidos se comparan con los de otros autores

Análisis mediante elementos de contorno de problemas de propagación cuasi-estática de fisuras

XIV Encuentro del Grupo Español de Fractura, celebrado en Ribadesella en 1997En esta comunicación se presenta la formulación mixta del Método de los Elementos de Contorno para la resolución de problemas bidimensionales de propagación cuasi-estática de grietas dentro del régimen elástico-lineal. Mediante la formulación mixta del Método de los Elementos de Contorno pueden analizarse problemas de fractura discretizando únicamente el contorno del dominio bajo consideración y ambas caras de la grieta, lo cual reduce enormemente el trabajo de modelado y remallado. Los factores de intensidad de tensiones en el vértice de la grieta, en modo I, II o mixto, se calculan de manera directa a partir de los desplazamientos de apertura y cizalladura del elemento adyacente al vértice. A partir de los factores de intensidad de tensión se ha calculado la dirección de propagación mediante el criterio de la mínima energía de deformación. En esta dirección se incrementa la longitud de la grieta simplemente añadiendo un nuevo elemento, sin necesidad de un costoso remallado del dominio, tal y como ocurre en otros métodos. Se muestra finalmente una serie de problemas de crecimiento cuasi-estático de fisuras.In this paper the mixed formulation of the Boundary Element Method is presented. This formulation is used to solving quasi-static crack propagation problems within the Linear Elas­tic Fracture Mechanics framework. The meshing effort is greatly reduced in the Mixed Boundary Element Method since only the exterior boundary and both faces of the crack have to be meshed. The Stress Intensity Factors, in mode I, II or mixed, are obtained form the crack opening and shearing displacement computed in a special element adjacent to crack tip. From the Stress In­tensity Factors the crack propagation path can be predicted. The mínimum strain energy density criterion has been used in this communication to predict. In the predicted direction the crack is extended simply appending a new boundary element, so there is no need of a complex remeshing effort as it happens in sorne other methods, Finally severa! problems of quasi-static crack-growth are shown

On the Design of Ambient Intelligent Systems in the Context of Assistive Technologies

The design of Ambient Intelligent Systems (AISs) is discussed in the context of assistive technologies. The main issues include ubiquitous communications, context awareness, natural interactions and heterogeneity, which are analyzed using some examples. A layered architecture is proposed for heterogeneous sub-systems integration with three levels of interactions that may be used as a framework to design assistive AISs.Ministerio de Ciencia y Tecnología TIC2001-1868-C0

Impedancias dinámicas en zapatas rígidas y flexibles sobre medios viscoelásticos

Se presentan aplicaciones recientes del Método de los Elementos de Contorno al cálculo de impedancias de cimentaciones en terrenos viscoelásticos, haciendo especial hincapié en el tratamiento de medios estratificados para problemas con simetría de revolución y en la forma de tratar zapatas flexibles

3D Eddy-Current Imaging of Metal Tubes by Gradient-Based, Controlled Evolution of Level Sets

9 pagesInternational audienceEddy-current non-destructive testing is widely used to detect defects within a metal structure. It is also useful to characterize their location and shape provided that proper maps of variations of impedance which the defects induce are available. Imaging of void defects in the wall of a hollow, non-magnetic metal tube, is performed herein by controlled evolution of level sets. Such data are variations of impedance collected by a circular probe array close to the inner surface of the tube when a coil source operated at one single frequency is set along its axis at some distance from the array, both receiver and coil source being moved simultaneously. The defect zone is represented in implicit fashion as a zero level set, amenable to topological changes via a nonlinear iterative method that minimizes a least-square cost functional made of the difference between the measured (computer simulated) and model data. The procedure involves the rigorous calculation of the gradient of the variations of impedance, in the case of a multi-static configuration, a vector domain integral field formulation being used to that effect. Numerical examples, via a dedicated extension of the general-purpose CIVA platform, exhibit pros and cons of the approach for inner, outer, and through-wall void defects, with further comparisons to results provided by an independently-developed binary-specialized method