Asymptotic-Preserving scheme for a bi-fluid Euler-Lorentz model

The present work is devoted to the simulation of a strongly magnetized plasma considered as a mixture of an ion fluid and an electron fluid. For the sake of simplicity, we assume that the model is isothermal and described by Euler equations coupled with a term representing the Lorentz force. Moreover we assume that both Euler systems are coupled through a quasi-neutrality constraint. The numerical method which is described in the present document is based on an Asymptotic-Preserving semi-discretization in time of a variant of this two-fluid Euler-Lorentz model with a small perturbation of the quasi-neutrality constraint. Firstly, we present the two-fluid model and the motivations for introducing a small perturbation into the quasi-neutrality equation, then we describe the time semi-discretization of the perturbed model and a fully-discrete finite volume scheme based on it. Finally, we present some numerical results which have been obtained with this method

Challenges to support automated random testing for dynamically typed languages

International audienceAutomated random testing is a proven way to identify bugs and precondition violations, and this even in well tested libraries. In the context of statically typed languages, current automated random testing tools heavily take advantage of static method declaration (argument types, thrown exceptions) to constrain input domains while testing and to identify errors. For such reason, automated random testing has not been investigated in the context of dynamically typed languages. In this paper we present the key challenges that have to be addressed to support automated testing in dynamic languages

Assessing the Quality of your Software with MoQam

International audienceOver the last decade, the need for quality in software has increased. Several quality models have been proposed [4, 6, 11]. These mod- els emphasize the need to have quality checks while developing a software program. As far as we are aware of, no model to assess quality of existing software have reached a significant acceptance. This paper describes the Qualixo quality model. Qualixo is an open-source quality model developed by several companies and pushed further in the context of the Squale research project. Ac- cording to Marinescu and Ratiu [9], Qualixo can be classified as a Factor-Criteria-Metrics quality model. Qualixo is being applied in large companies such as AirFrance or PSA. It uses measurements to assess software quality. These measurements cover a number of different aspects of a software, including specification accuracy, programming rules, and test coverage. Qualixo has been origi- nally implemented on top of Eclipse. In this paper we present Mo- Qam (Moose Quality Assessment Model), the implementation of the Qualixo quality model in the Moose open-source reengineering environment

Numerical resolution of an anisotropic non-linear diffusion problem

International audienceThis paper is devoted to the numerical resolution of an anisotropic non-linear diffusion problem involving a small parameter ε, defined as the anisotropy strength reciprocal. In this work, the anisotropy is carried by a variable vector function b. The equation being supplemented with Neumann boundary conditions, the limit ε → 0 is demonstrated to be a singular perturbation of the original diffusion equation. To address efficiently this problem, an Asymptotic-Preserving scheme is derived. This numerical method does not require the use of coordinates adapted to the anisotropy direction and exhibits an accuracy as well as a computational cost independent of the anisotropy strength