Search results for "Geometric"
showing 10 items of 652 documents
A predictive approach for a real-time remote visualization of large meshes
2012
Déjà sur HAL; Remote access to large meshes is the subject of studies since several years. We propose in this paper a contribution to the problem of remote mesh viewing. We work on triangular meshes. After a study of existing methods of remote viewing, we propose a visualization approach based on a client-server architecture, in which almost all operations are performed on the server. Our approach includes three main steps: a first step of partitioning the original mesh, generating several fragments of the original mesh that can be supported by the supposed smaller Transfer Control Protocol (TCP) window size of the network, a second step called pre-simplification of the mesh partitioned, ge…
La théorie des lignes parallèles de Johann Heinrich Lambert
2014
International audience; The memoir "Theory of parallel lines" (1766) by Johannes Heinrich Lambert is one of the founding texts of hyperbolic geometry, even though his author conceived it as an attempt to show that this geometry does not exist. In fact, Lambert developed that theory with the hope of finding a contradiction. In doing so, he obtained several fundamental results of hyperbolic geometry. This was sixty years before the first writings of Lobachevsky and Bolyai appeared in print. This book contains the first complete translation of Lambert's memoir as well as mathematical and historical commentaries.
Coplanar control of a satellite around the Earth
2001
We investigate the minimum time transfer of a satellite around the Earth. Using an optimal control model, we study the controllability of the system and propose a geometrical analysis of the optimal command structure. Furthermore, in order to solve the problem numerically, a new parametric technique is introduced for which convergence properties are established.
Variational methods in imaging and geometric control
2016
International audience
A combination of algebraic, geometric and numerical methods in the contrast problem by saturation in magnetic resonance imaging
2014
In this article, the contrast imaging problem by saturation in nuclear magnetic resonance is modeled as a Mayer problem in optimal control. The optimal solution can be found as an extremal solution of the Maximum Principle and analyzed with the recent advanced techniques of geometric optimal control. This leads to a numerical investigation based on shooting and continuation methods implemented in the HamPath software. The results are compared with a direct approach to the optimization problem and implemented within the Bocop toolbox. In complement lmi techniques are used to estimate a global optimum. It is completed with the analysis of the saturation problem of an ensemble of spin particle…
Implementation of single-qubit quantum gates by adiabatic passage and static laser phases
2006
International audience; We propose and analyse experimentally feasible implementations of single-qubit quantum gates based on stimulated Raman adiabatic passage (STIRAP) between magnetic sublevels in atoms coupled by elliptically polarized pulsed laser fields, in part based on a proposal by Kis and Renzoni [Z. Kis, F. Renzoni, Phys. Rev. A 65 (2002) 032318]. These techniques require only the control of the relative phase of the driving fields but do not involve any dynamical or geometric phases, which makes it independent of the other interaction details: detuning, pulse shapes, pulse areas and pulse durations. The suggested techniques are immune to spontaneous emission since the qubit mani…
Modelling of interference fits with taking into account surfaces roughness with homogenization technique
2013
International audience; The assembly technique by shrink fit is increasingly used today because it allows for the assembly of two pieces without any intermediary part simply by the tightening effect given by the difference in diameters of the two parts assembled. The definition of assemblies depends on calculation models available in the standard. They make very restrictive assumptions that limit the geometrical defects and the surface finish. It is increasingly common to use a finite element method to better adapt the model to the complex forms of industrial parts. However, the standard is limited with regard to the consideration of roughness which results in a loss of tightening. An easy …
Path Planning in Inspection Process of 3-D Parts Used the Visibility Technique
2006
International audience; In this paper presents a new method for digitalization of parts with non-contact sensor remains nevertheless complex. It is not completely solved today, in particular from a metrological point of view. In this article, we consider the determination of the trajectory planning within the framework of the control of dimensional and geometrical specifications. The sensor used in this application is a laser planner scanner with CCD camera oriented and moved by a CMM. Thus, we seek to determine which are the best possible orientations of the sensor with respect to the geometrical specifications of the measured part, giving the admissible measurement uncertainties. The deve…
3D surfaces automated acquisition using non contact sensor with repect of metrological conditions
2013
International audience
Modélisation géométrique de formes fractales pour la CAO
2020
International audience