Wave Computation on the Hyperbolic Double Doughnut

We compute the waves propagating on the compact surface of constant negative curvature and genus 2. We adopt a variational approach using finite elements. We have to implement the action of the fuchsian group by suitable boundary conditions of periodic type. A spectral analysis of the wave allows to compute the first eigenvalues of the Laplace-Beltrami operator. We test the exponential decay due to a localized dumping and the ergodicity of the geodesic flow.Comment: 13 pages, 6 figure

Forecasting of Object-Oriented Faults

International audienceObject-Oriented Technologies, such as Java, provide efficient features to develop software applications. In particular, they allow the development costs to be reduced. However, issues highlighted by the “Object- Oriented Technology in Aviation” group have to be handled to guarantee a high level of safety, in order to use such technologies in avionics software. In particular, the risk of Object-Oriented Technologies design faults has to be reduced to an acceptable level. These risk reduction actions must be preceded by forecasting the actual risk level of the developed application. The paper aims at presenting a method used to forecast the risk of the presence of these Object-Oriented Technologies faults in a given program. The approach proposed is based on Bayesian networks. Its principles are introduced. It is illustrated on an example of faults: the Accidental Overriding (AO). We highlight that our approach takes into account the complex relationships existing between the various object-oriented features: inheritance, distribution of the attributes and methods, etc. To conclude, we show how the obtained data can be analysed to specify design guidelines allowing an acceptable risk level to be reached

Formalizing Safety Requirements Using Controlling Automata

Safety is an important element of dependability. It is defined as the absence of accidents. Most accidents involving software-intensive systems have been system accidents, which are caused by unsafe inter-system or inter-component interactions. To validate the absence of system hazards concerning dysfunctional interactions, industrials call for approaches of modeling system safety requirements and interaction constraints among components. This paper proposes such a formalism, namely interface control systems (or shortly C-Systems). An interface C-System is composed of an interface automaton and a controlling automaton, which formalizes safe interactions and restricts system behavior at the meta level. This framework differs from the framework of traditional model checking. It explicitly separates the tasks of product engineers and safety engineers, and provides a top-down technique for modeling a system with safety constraints, and for automatically composing a safe system that conforms to safety requirements. The contributions of this work include formalizing safety requirements and a way of automatically ensuring system safety.Comment: 6 pages. In Proceedings of the 2nd International Conference on Dependability (DEPEND 2009), Athens, Greece. IEEE Computer Society, 200

Identification Model of the Object Oriented Technology risks, for Avionics Certification

International audienceThe introduction of any new technology in an existing industrial process has a dual effect: on the one hand, it is expected to bring some well-identified benefits, but on the other hand, it also brings a certain number of new risks. It is the role and responsibility of decision makers, designers, and developers to estimate and balance these two aspects, taking into account the very specific characteristics of their industrial domain. In the domain of software systems, for instance, object-oriented technologies have been demonstrated to increase software quality and productivity, but they simultaneously bring some specific risks that must be carefully characterized and handled, especially when they are integrated in the development of software applications for critical systems. In the avionics domain, the OOTiA document proposes a first and informal identification of some of these risks. However this identification process misses the formal background that would guarantee its consistency and completeness. In this paper, we suggest to fill this gap by considering the management of software risk as a specific case of industrial risk management. To achieve this goal, we propose a generic model for the identification of software risks. This model provides the information required by the subsequent phases of risk management: risk estimation, risk acceptance, and risk mitigation

Toward a Human-Centered Uml for Risk Analysis

Safety is now a major concern in many complex systems such as medical robots. A way to control the complexity of such systems is to manage risk. The first and important step of this activity is risk analysis. During risk analysis, two main studies concerning human factors must be integrated: task analysis and human error analysis. This multidisciplinary analysis often leads to a work sharing between several stakeholders who use their own languages and techniques. This often produces consistency errors and understanding difficulties between them. Hence, this paper proposes to treat the risk analysis on the common expression language UML (Unified Modeling Language) and to handle human factors concepts for task analysis and human error analysis based on the features of this language. The approach is applied to the development of a medical robot for teleechography

1.4 ps rise‐time high‐voltage photoconductive switching

We report on the generation of 825 V electrical pulses with 1.4 ps rise time and 4.0 ps duration using a pulse‐biased low‐temperature‐grown GaAs photoconductive switch triggered by an amplified femtosecond dye laser. Dependence of the pulse shape on both electric field and optical energy is observed and discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70925/2/APPLAB-59-12-1455-1.pd

UML Inconsistencies Assessment

International audienceThe UML modelling language provides diagrams allowing multiple viewpoints of one system to be described. However, certain sets of elements of a model can be inconsistent. Inconsistencies are not drawbacks of the language as they highlight the presence of faults in the models. This paper proposes an assessment of the inconsistencies in order to estimate the effort which must be provided to handle them

Chemie ist Leben – (über)lebt die Chemie?

International audienceBrief bibliographical information : The team EMC of LESIA/INSA works on emission and susceptibility of electronic systems in cooperation with numerous firms from several domains including avionics (EADS) and automotive (Motorola, Siemens VDO). The team is a co-author of the standard IEC 62014-3, the organizer of the international conference EMC Compo and participates to the European projects MESDIE and LIMA

Understanding Interactive Dynamic Situations

Abstract The system presented here is developed to interpret dynamic situations involving several moving objects in a known environment. It is part of the ESPRIT VIEWS project and processes data coming from sequences of video frames. These numerical data are interpreted to identify in real-time situations including complex interactions between moving objects in the scene. The principle is to compile pre-defined behaviours for individual objects then for groups of objects from elementary events. The method used to accomplish this is based on temporal networks and dynamic grouping. The applications studied here consists in the detection of incidents on an urban roundabout