8720 articles  [english version]

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Publications HAL de la collection INRIA-RRRT

2014

Titre
Construction et validation des éléments Serendip associés á un carreau de degré arbitraire
Auteurs
Paul-Louis George; Houman Borouchaki; Nicolas Barral
Détail
[Research Report], 2014, pp. 107. RR-8572
Début du résumé
We give a method to constructing Serendipity elements for quads and hexes with full symmetry properties and indicate the reading of their shape functions. We show that, since the degree~5, the Serendipity elements are no longer symmetric but we propose a method resulting in a Lagrange element of degree 5 with full symmetry properties after adding an adequate number of additional nodes. On the other hand, we show how to guarantee the geometric validity of a given curved element (seen as a patch) of a mesh. This is achieved after writing the patch in a Bézier setting (Bernstein polynomials and .....
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Titre
Construction et validation des éléments réduits associés á un carreau simplicial de degré arbitraire
Auteurs
Paul-Louis George; Houman Borouchaki; Nicolas Barral
Détail
[Research Report], 2014, pp. 55. RR-8571
Début du résumé
We give a method to constructing Lagrange Serendipity (or reduced) simplices with a detailed description of the triangles of degree 3 and 4. We indicate that higher order triangles are not candidate apart if we impose a restricted polynomial space. We show that a tetrahedron of degree 3 is a candidate while high order elements are not candidate even if a restriction in the polynomial space is considered. In addition, we propose a method for the validation of such elements, in a given mesh, where the validation means the positiveness of the jacobian .....
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Titre
Can Homomorphic Cryptography ensure Privacy?
Auteurs
Antoine Guellier
Détail
[Research Report], 2014, pp. 111. RR-8568
Début du résumé
The advent of information technology, the dramatic increase of computational and storage capacities along with the development of worldwide communications promise very personalized, well designed and convenient services. However, although privacy is an important right in our societies, these services often neglect and abuse their consumers' privacy, by collecting sensible data notably. This work focuses on the protection of privacy in information systems. For this, it is known that traditional cryptography (e.g. encryption or signature schemes) is necessary, for instance to ensure confidentiality, but it is not sufficient. To enable usability and privacy at the same time, stronger tools are .....
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Titre
Combinatorial optimization in networks with Shared Risk Link Groups
Auteurs
David Coudert url; Stéphane Pérennes; Hervé Rivano url; Marie-Emilie Voge
Détail
[Research Report], 2014, pp. 26. RR-8575
Début du résumé
The notion of Shared Risk Link Groups (SRLG) captures survivability issues when a set of links of a network may fail simultaneously. The theory of survivable network design relies on basic combinatorial objects that are rather easy to compute in the classical graph models: shortest paths, minimum cuts, or pairs of disjoint paths. In the SRLG context, the optimization criterion for these objects is no longer the number of edges they use, but the number of SRLGs involved. Unfortunately, computing these combinatorial objects is NP-hard and hard to approximate with this objective in general. Nevertheless some objects can be computed .....
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Titre
A Simple Two-Dimensional Extension of the HLL Riemann Solver for Gas Dynamics
Auteurs
Jeaniffer Vides; Boniface Nkonga; Edouard Audit
Détail
[Research Report], 2014. RR-8540
Début du résumé
We report on our study aimed at deriving a simple method to numerically approximate the solution of the two-dimensional Riemann problem for gas dynamics, using the literal extension of the well-known HLL formalism as its basis. Essentially, any strategy attempting to extend the three-state HLL Riemann solver to multiple space dimensions will by some means involve a piecewise constant approximation of the complex two-dimensional interaction of waves, and our numerical scheme is not the exception. In order to determine closed form expressions for the involved fluxes, we rely on the equivalence between the consistency condition and the use of Rankine-Hugoniot .....
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