Safety Evaluation of Critical Applications Distributed on TDMA-Based Networks

Critical embedded systems have to provide a high level of dependability. In automotive domain, for example, TDMA protocols are largely recommended because of their deterministic behavior. Nevertheless, under the transient environmental perturbations, the loss of communication cycles may occur with a certain probability and, consequently, the system may fail. This paper analyzes the impact of the transient perturbations (especially due to Electromagnetic Interferences) on the dependability of systems distributed on TDMA-based networks. The dependability of such system is modeled as that of "consecutive-k-out-of-n:F" systems and we provide a efficient way for its evaluation

Claude Parent, the Risk erected in Operating Mode

La totalidad de la obra de Claude Parent puede ser entrepretada como una constante oposición al academicismo, el poder, el reconocimiento social e incluso las leyes que rigen la lógica estructural de la arquitectura. De este modo, obras como la Maison Soultrait o la Iglesia de Sta. Bernadette se postulan como auténticos manifiestos de límite, violentos y contradictorios. Casos de estudio que serán interpretados desde la catástrofe de sus tiempos presentes.ENG: The whole work of Claude Parent can be interpreted like a constant opposition to academicism, power, social recognition and even the laws that govern the structural logic of architecture. Thus, works such as the Maison Soultrait or the Church of St. Bernadette are postulated as real risky maniphestos, violent and contradictory. Case studies to be interpreted from the catastrophe of our present times.Peer Reviewe

Un référentiel des compétences documentaires utiles en premier cycle universitaire

Intervention à la 3e journée FORMIST qui s\u27est déroulée à l\u27enssib le 12 juin 2003

Matrix method to predict the spectral reflectance of stratified surfaces including thick layers and thin films

The most convenient way to assess the color rendering of a coated, painted, or printed surface in various illumination and observation configurations is predict its spectral, angular reflectance using an optical model. Most of the time, such a surface is a stack of layers having different scattering properties and different refractive indices. A general model applicable to the widest range of stratified surfaces is therefore appreciable. This is what we propose in this paper by introducing a method based on light transfer matrices: the transfer matrix representing the stratified surface is the product of the transfer matrices representing the different layers and interfaces composing it, each transfer matrix being expressed in terms of light transfers (e.g. diffuse reflectances and transmittances in the case of diffusing layers). This general model, inspired of models used in the domain of thin films, can be used with stacks of diffusing or nonscattering layers for any illumination-observation geometry. It can be seen, in the case of diffusing layers, as an extension of the Saunderson-corrected Kubelka-Munk model and Kubelka's layering model. We illustrate the through an experimental example including a thin coating, a thick glass plate and a diffusing background. 2. Introduction For a long time, the variation of the spectral properties of surfaces and objects by application of coatings has been a wide subject of investigation for physicians who proposed several models based on specific mathematical formalisms according to the type of physical components and the application domain. In the domain of paints, papers, and other diffusing media, a classical approach is to use the Kubelka-Munk system of two coupled differential equations to describe the propagation of diffuse fluxes in the medium [1,2]. The extension of this model by Kubelka to stacks of paint layers is based on geometrical series describing the multiple reflections and transmissions of these diffuse fluxes between the different layers [3,4]. Geometrical series were also used by Saunderson [5] when deriving his correction of the Kubelka-Munk model in order to account for the internal reflections of light between the paint layer and the paint-air interface, by Clapper and Yule [6] in their reflectance mode

Assessing the capacity of two-flux models to predict the spectral properties of layered materials

International audienceA classical way of coloring a surface in order to create a still image is the application of a colored coating. The more recent digital printing systems enable depositing thick coatings or successive ink layers. The color rendering of the surface depends on the optical properties of the coated materials (optical index, spectral scattering and absorption coefficients) and their thickness. In order to predict its spectral reflectance as a function of these parameters, the so-called two-flux approach is to be tested in first since the model is simple and relies on analytical equations. It has a good chance to provide accurate predictions for coatings made of solid layers of strongly scattering or nonscattering media, or even complex stratified coatings obtained by stacking nonsymmetrical components such as printed films. The generalized Kubelka-Munk model summarized in this paper enables treating all these configurations with a unified mathematical formalism. But it has limitations and may provide poor color predictions for certain types of layered materials. We therefore propose a simple method based on parameters of the model to check the precision of the two-flux model for a given type of coating

Modélisation de la diffusion multiple de la lumière dans un réseau cubique selon une approche discrète

La modélisation de la diffusion multiple de la lumière doit prendre en compte la localisation spatiale des éléments diffusants, et la répartition angulaire des flux donnée par la diffusion simple. Le problème général étant complexe, de nombreuses méthodes de résolution ont été proposées selon des hypothèses simplificatrices. Nous présentons une méthode originale basée sur la discrétisation des éléments diffusants supposés formés un réseau cubique, et sur le découpage en six flux de la lumière diffusée par une seule particule. Cette méthode à six flux avec discrétisation sur les trois dimensions spatiales peut être considérée comme une extension tridimensionnelle de la méthode de Kubelka [Kubelka48] (méthode à deux flux avec discrétisation sur une seule dimension spatiale). Avec un nombre de paramètres réduits pour décrire la diffusion simple (au minimum trois paramètres indépendants : probabilités d'absorption, de diffusion vers l'avant et vers l'arrière), ce nouveau modèle permet d'accéder à la répartition de la lumière diffusée latéralement dans le matériau

Should We "Redshirt" in Kindergarten? A Study of the Effect of Age on Kindergarteners' Reading Readiness

This study examined the effect of chronological age on kindergarten children's reading readiness skills. Specifically, we ask whether chronological age should be considered when making decisions about academic redshirting: the practice of delaying younger children's entrance into kindergarten. We were concerned particularly with reading readiness because research has shown consistently that kindergarten children who demonstrate strong prereading skills such as phonological awareness and letter-sound understanding are more likely to become strong readers in later grades (Snow, Burns, & Griffin, 1998). The participants in this study were 625 kindergarten children who were measured for age, phonological awareness, and letter-sound understanding. Results of analysis indicate that younger children were no different from their older peers in their phonological awareness skills whereas significant between-group differences did occur for letter-sound understanding. These results give strength to the notion that younger children in kindergarten were comparable to older children in their phonological awareness skills. However, younger children were less skilled in understanding letter-sound relationships.Cette étude porte sur l'effet de l'âge chronologique sur les habiletés relatives à la capacité de lecture d'enfants à la maternelle. Plus précisément, nous considérons s'il faudrait tenir compte de l'âge chronologique lors de la prise de décision impliquant la pratique académique de "redshirting" qui consiste à retarder l'entrée à la maternelle d'enfants plus jeunes. Nous nous sommes penchés sur la préparation à la lecture, les recherches démontrant, de façon persistante, que les enfants de la maternelle qui font preuve d'habiletés de prélecture - telles la conscience phonologique et le sens de la relation grapho-phonémique - très développées sont plus aptes à devenir de bons lecteurs plus tard (Snow, Burns, & Griffin, 1998). Les enfants qui ont participé à cette étude, 625 jeunes de la maternelle, ont été évalués en fonction de leur âge, leur conscience phonologique et leur sens de la relation grapho-phonémique. L'analyse des données a révélé qu'il n'y avait pas de différences dans les habiletés liées à la conscience phonologique entre les enfants plus jeunes et leurs pairs plus âgés. Pour le sens de la relation grapho-phonémique toutefois, les différences entre les groupes d'âge étaient importantes. Ces résultats viennent appuyer la notion selon laquelle les habiletés liées à la conscience phonologique chez les enfants plus jeunes sont comparables à celles des enfants plus âgés. Les plus jeunes, par contre, comprenaient moins bien la relation grapho-phonémique

Two-flux transfer matrix model for predicting the reflectance and transmittance of duplex halftone prints

International audienceWe introduce a model allowing convenient calculation of the spectral reflectance and transmittance of duplex prints. It is based on flux transfer matrices and enables retrieving classical Kubelka-Munk formulas, as well as extended formulas for non-symmetric layers. By making different assumptions on the flux transfers, we obtain two predictive models for the duplex halftone prints: The "duplex Clapper-Yule model" which is an extension of the classical Clapper-Yule model, and the "duplex primary reflectance-transmittance model". The two models can be calibrated from either reflectance or transmittance measurements; only the second model can be calibrated from both measurements, thus giving optimal accuracy for both reflectance and transmittance predictions. The conceptual differences between the two models are deeply analyzed, as well as their advantages and drawbacks in terms of calibration. According to the test carried out in this study with paper printed in inkjet, their predictive performances are good provided appropriate calibration options are selected