Dynamic condensation and selective mass scaling in RADIOSS Explicit

RADIOSS Explicit is a famous industrial FE code largely used for dynamic problems. To reduce the computation time, both dynamic condensation and selective mass scaling are used to increase the critical time step without modifying the low frequencies response, neither the rigid body momentum. The implementation of these two methods is discussed. Then the performances and limits of these methods are illustrated through some use cases, issued from crash and stamping process simulations

Towards Coq-verified Esterel Semantics and Compiling

This paper focuses on semantics of the Esterel synchronous programming language. In particular, in addition to the usual behavioral (CBS) and state (CSS) semantics, it introduces a novel microstep semantics which does not need the Can potential function. Formal proofs in Coq of the equivalence between the CBS and CSS semantics and of the refinement between the CSS and microstep semantics are also provided

An AOP Layer to Abstract Programming with Distributed Components

International audienceComponent models such as EJB or CCM are increasingly used to create complex and distributed systems and applications. Unless the details of the API and mechanisms used for programming with these models differ, the general features provided by the models share many characteristics. In this paper, we propose to capture these features in a common layer that can be used to develop model independant component programs. The layer is then mapped either onto EJB or CCM. This layer is defined with the AspectJ aspect-oriented programming language. We report on two samples applications that were developped with this layer: an application-level load balancing service and a contract enforcement service

Une industrie pré-acheuléenne en Brivadois (Haute-Loire): A pre-acheulian assemblage in Brivadois (Haute-Loire)

pdf du manuscritNational audienceA pebble-tools assemblage made of quartz has been recently discovered near Brioude on a high terrace of the Allier river. It brings us details about the first phases of the succession previously established from the sites of Bourbonnais. According to indirect dating data, one can estimate the age between 0.8 and 0.5 M.aUn outillage sur galets de quartz a été récemment découvert près de Brioude, en surface d'une haute terrasse de l'Allier. Il permet de préciser les caractères des stades anciens du schéma évolutif établi à partir des nombreux gisements du Bourbonnais. En fonction des éléments de datation indirecte, l'âge de ces objets est estimé entre 0,8 et 0,5 M.a

Structural interpretation of the modification of soda-lime-silica glass properties by P2O5

The influence of P2O5 addition on soda-lime-silica glass properties is discussed on the basis of a structural model. It involves two effects: Insertion of phosphate molecular complexes into the silicate network interstices, and increase in silicate network condensation. The latter results from the scavenging of sodium and calcium cations by P2O5. The properties considered in this paper are high-temperature viscosity and liquidus temperature. The P2O5 additions are in the 0.8 to 3.0 mol% range. The silica content of the glasses varies from 60 to 67 mol%, and the ratio CaO/(CaO+Na2O) from 0 to 0.85. Phosphate molecular complexes decrease the liquidus temperature and the high-temperature viscosity increasing the network condensation results in an increase in the viscosity, but its effect on the liquidus temperature depends on whether the glass composition lies on an upward or downward liquidus surface of the phase diagram

Dissolution of (50-x)Na₂O-xCaO-50P₂O₅ metaphosphate glasses in different saline Solutions: mechanism and kinetic control

The dissolution of (50-x)Na₂O-xCaO-50P₂O₅ metaphosphate glasses has been investigated at pH 3 in Solutions containing in Na⁺, Ca²⁺, Cl⁻, NO₃⁻ and (PO₃⁻)n ions. Whatever the conditions, a hydrated layer develops over a surface covered with etch pits. Na⁺ and Cl⁻ have no specific effect on the dissolution kinetics and mechanism. In Ca²⁺-containing Solutions, XPS, electrophoretic mobility and ³¹P NMR show that Na⁺ is exchanged for Ca²⁺ in the hydrated layer, resulting in a decreased dissolution rate. Polyphosphate anions, (PO₃⁻)n, act as complexing agent for Ca²⁺, and counterbalance its inhibiting effect on the dissolution rate

Ultrasonic Inspection of Titanium Alloys with a Time Reversal Mirror

Ultrasonic Time Reversal Mirror (TRM) is an original solution to detect small cracks in a solid of any geometrical shape. Indeed, nondestructive testing need high resolution capabilities, high reliability and shortest control time. But the more recent techniques need an a priori knowledge of the liquid-solid interface and present limitations. The first of these uses several large prefocussed arrays, one array for each testing depth. Therefore this control system is sensitive to the arrays alignment, limited by the array precision focusing, and requires a complex mechanical follower system. A greater flexibility can be obtained by a second technique that is based on delay lines. But an accurate knowledge of the interface and a high calculs resolution are indispensable

Internal structure and fragmentation kinetics of silica granules

International audienceTo improve the mechanical properties of tires, silica granules can be incorporated into the elastomer as well as carbon black. Ideally, the fragmentation of the granules in the elastomer must be obtained with low mechanical stresses and lead to very small fragments distributed homogeneously in the material. On the other hand, granules must present a sufficient cohesion, in order to avoid the generation of fine particles during handling operations. Thus it appears necessary to control the mechanical strength of granules and the mechanism of their fragmentation. In this experimental study, we investigated the fragmentation of silica granules of 250 microns produced by spray drying. For this, we characterized by granulometry the evolution of the Particle Size Distribution of silica powder in water. The granules were suspended in water and submitted to ultrasounds. This treatment is used to create the fragmentation that occurs by viscous shearing in industrial rubber processing. A core-shell structure, characteristic of granules obtained by atomization process, was observed by SEM. Furthermore, by varying the intensity of mechanical stress, the multi-scale structure of granules was evidenced as well as the existence of different regimes of fragmentation. The kinetics of fragmentation was experimentally followed on two grades of silica that showed significant differences in their behavior during the fragmentation process

Aspect-Oriented Software Development with Java Aspect Components

In the last four years, our research project dealt with separation of concerns for distributed programming environments and applications. This research effort led to the implementation of the Java Aspect Component (JAC) framework for aspect-oriented programming (AOP) in Java. Among the many requirements for distribution, flexibility and adaptability play a stringent role. The high variability of executing conditions (in terms of resources, servers availability, faults, ...) also brings the need for powerful programming paradigms. This led us to develop a dynamic model of AOP which, unlike statically compiled approaches, allows to on-the-fly deploy and undeploy aspects on top of running applications. This model comes with an UML notation and an implementation. An IDE is provided with JAC to support all the development steps of an aspect oriented application, from its design, to its implementation, to its deployment