Results for "Taoufik Ouali"

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Dynamical system approach of non-minimal coupling in AdS/CFT cosmologyMay 08 2018Nov 13 2018We study the dynamical system approach of non minimally coupled scalar field to induced gravity on the brane in the framework of the AdS/CFT correspondence. In this context, we derive the modified Friedmann equation and the equation of motion. The dynamics ... More
Constraints on tachyon inflationary models with an AdS/CFT correspondenceOct 06 2016Nov 14 2016In order to study the effect of the anti de Sitter/ conformal field theory correspondence (AdS/CFT) on the primordial inflationary era, we consider a universe filled with a tachyon field in a slow-roll regime. In this context, the background and perturbative ... More
Constraints on tachyon inflationary models with an AdS/CFT correspondenceOct 06 2016In order to study the effect of the anti de Sitter/ conformal field theory correspondence (AdS/CFT) on the primordial inflationary era, we consider a universe filled with a tachyon field in a slow-roll regime. In this context, the background and perturbative ... More
Induced gravity effect on inflationary parameters in an holographic cosmologyApr 12 2019We investigate observational constraints on inflationary parameters in the context of an holographic cosmology with an induced gravity correction. We consider two situations where a universe is firstly filled with a scalar field and secondly with a tachyon ... More
An existence result of energy minimizer maps between riemannian polyhedraAug 18 2004Sep 29 2004In this paper, we prove the existence of energy minimizers in each free homotopy class of maps between polyhedra with target space without focal points. Our proof involves a careful study of some geometric properties of riemannian polhyedra without focal ... More
Bifurcation of rotating patches from Kirchhoff vorticesAug 19 2015Sep 14 2015In this paper we prove the existence of countable branches of rotating patches bifurcating from the ellipses at some implicit angular velocities.
The little sibling of the big rip singularityJul 09 2014Jun 24 2015We present a new cosmological event, which we named the little sibling of the big rip. This event is much smoother than the big rip singularity. When the little sibling of the big rip is reached, the Hubble rate and the scale factor blow up but the cosmic ... More
Existence of corotating and counter-rotating vortex pairs for active scalar equationsJan 10 2016In this paper, we study the existence of corotating and counter-rotating pairs of simply connected patches for Euler equations and the generalized SQG equations with $\alpha\in ]0,1[.$ From the numerical experiments implemented for Euler equations in ... More
Mixed finite element formulation in large deformation frictional contact problemFeb 08 2005In this paper, we propose an efficient numerical treatment for solving contact problems with friction between deformable bodies. The discretized normal and tangential constraints at the candidate contact interface are expressed by using either continuous ... More
On the global well-posedness of the critical quasi-geostrophic equationFeb 08 2007We prove the global well-posedness of the critical dissipative quasi-geostrophic equation for large initial data belonging to the critical Besov space $\dot B^0_{\infty,1}(\RR^2).$
Small $\dot B^{-1}_{\infty,\infty}$ implies regularitySep 08 2016We show that smallness of $\dot B^{-1}_{\infty,\infty}$ norm of solution to $d$-dimensional ($d\ge 3$) incompressible Navier-Stokes prevents blowups.
On the global solutions of the super-critical 2D quasi-geostrophic equation in Besov spacesNov 16 2006In this paper we study the super-critical 2D dissipative quasi-geostrophic equation. We obtain some regularization effects allowing us to prove global well-posedness result for small initial data lying in critical Besov spaces constructed over Lebesgue ... More
Existence of small loops in the Bifurcation diagram near the degenerate eigenvaluesAug 30 2016In this paper we study for the incompressible Euler equations the global structure of the bifurcation diagram for the rotating doubly connected patches near the degenerate case. We show that the branches with the same symmetry merge forming a small loop ... More
Spectral distribution of the free unitary Brownian motion: another approachMar 24 2011We revisit the description provided by Ph. Biane of the spectral measure of the free unitary Brownian motion. We actually construct for any $t \in (0,4)$ a Jordan curve $\gamma_t$ around the origin, not intersecting the semi-axis $[1,\infty[$ and whose ... More
On the global well-posedness for Euler equations with unbounded vorticityMar 25 2013In this paper, we are interested in the global persistence regularity for the 2D incompressible Euler equations in some function spaces allowing unbounded vorticities. More precisely, we prove the global propagation of the vorticity in some weighted Morrey-Campanato ... More
General position of a projection and its image under a free unitary Brownian motionFeb 20 2013Apr 07 2013Given an orthogonal projection $P$ and a free unitary Brownian motion $Y = (Y_t)_{t \geq 0}$ in a $W^{\star}$-non commutative probability space such that $Y$ and $P$ are $\star$-free in Voiculescu's sense, the main result of this paper states that $P$ ... More
Degenerate bifurcation of the rotating patchesOct 15 2015In this paper we study the existence of doubly-connected rotating patches for Euler equations when the classical non-degeneracy conditions are not satisfied. We prove the bifurcation of the V-states with two-fold symmetry, however for higher $m-$fold ... More
Algorithm for the k-Position Tree Automaton ConstructionFeb 22 2015The word position automaton was introduced by Glushkov and McNaughton in the early 1960. This automaton is homogeneous and has (||\E||+1) states for a word expression of alphabetic width ||\E||. This kind of automata is extended to regular tree expressions. ... More
The cosmology of an holographic induced gravity model with curvature effectsApr 06 2011Sep 19 2011We present an holographic model of the Dvali-Gabadadze-Porrati scenario with a Gauss-Bonnet term in the bulk. We concentrate on the solution that generalises the normal Dvali-Gabadadze-Porrati branch. It is well known that this branch cannot describe ... More
An Efficient Algorithm for the Equation Tree Automaton via the $k$-C-ContinuationsJan 23 2014Champarnaud and Ziadi, and Khorsi et al. show how to compute the equation automaton of word regular expression $E$ via the $k$-C-Continuations. Kuske and Meinecke extend the computation of the equation automaton to a regular tree expression $E$ over a ... More
Root-Weighted Tree Automata and their Applications to Tree KernelsJan 16 2015In this paper, we define a new kind of weighted tree automata where the weights are only supported by final states. We show that these automata are sequentializable and we study their closures under classical regular and algebraic operations. We then ... More
K-Position, Follow, Equation and K-C-Continuation Tree Automata ConstructionsMar 25 2014Jul 11 2014There exist several methods of computing an automaton recognizing the language denoted by a given regular expression: In the case of words, the position automaton P due to Glushkov, the c-continuation automaton C due to Champarnaud and Ziadi, the follow ... More
Side-slipping of a radiating particleAug 01 2002Radiation reaction is revisited, first in a new classical aproach, where the physical particle 4-momentum is redefined as the energy-momentum flux across the future light cone and is not parallel to the 4-velocity. Then in a semi-classical approach, it ... More
On rotating doubly connected vorticesOct 01 2013In this paper we consider rotating doubly connected vortex patches for the Euler equations in the plane. When the inner interface is an ellipse we show that the exterior interface must be a confocal ellipse. We then discuss some relations, first found ... More
Boundary regularity of rotating vortex patchesAug 02 2012Oct 31 2014We show that the boundary of a rotating vortex patch (or V-state, in the terminology of Deem and Zabusky) is of class C^infinity provided the patch is close enough to the bifurcation circle in the Lipschitz norm. The rotating patch is convex if it is ... More
Maxwell's equations in the context of the Fock transformation and the magnetic monopoleFeb 28 2019In the R-Minkowski space-time, which we recently defined from an appropriate deformed Poisson brackets that reproduce the Fock coordinate transformation, we derive an extended form for Maxwell's equations by using a generalized version of Feynman's approach. ... More
Time-dependent delta-interactions for 1D Schrödinger HamiltoniansMar 31 2009The non autonomous Cauchy problem for time dependent 1D point interactions is considered. The regularity assumptions for the coupling parameter are accurately analyzed and show that the general results for non autonomous linear evolution equations in ... More
Visual object categorization with new keypoint-based adaBoost featuresOct 07 2009We present promising results for visual object categorization, obtained with adaBoost using new original ?keypoints-based features?. These weak-classifiers produce a boolean response based on presence or absence in the tested image of a ?keypoint? (a ... More
On the global existence for the axisymmetric Euler equationsMar 06 2007This paper deals with the global well-posedness of the 3D axisymmetric Euler equations for initial data lying in some critical Besov spaces
On the global well-posedness for the axisymmetric Euler equationsJan 15 2008This paper deals with the global well-posedness of the 3D axisymmetric Euler equations for initial data lying in critical Besov spaces $B_{p,1}^{1+3/p}$. In this case the BKM criterion is not known to be valid and to circumvent this difficulty we use ... More
Characterizing Quantum Properties of a Measurement Apparatus: Insights from the Retrodictive ApproachJun 30 2010Nov 02 2010Using the retrodictive approach of quantum physics, we show that the state retrodicted from the response of a measurement apparatus is a convenient tool to fully characterize its quantum properties. We translate in terms of this state some interesting ... More
Error estimates for Stokes problem with Tresca friction conditionMar 17 2010In this work we propose and study a three field mixed formulation for solving the Stokes problem with Tresca-type non-linear boundary conditions. Two Lagrange multipliers are used to enforce div(u)=0 constraint and to regularize the energy functional. ... More
BiHom-alternative, BiHom-Malcev and BiHom-Jordan algebrasNov 26 2018The purpose of this paper is to introduce and study BiHom-alternative algebras and BiHom-Malcev algebras. It is shown that BiHom-alternative algebras are BiHom-Malcev admissible and BiHom-Jordan admissible. Moreover, BiHom-type generalizations of some ... More
Global well-posedness for Euler-Boussinesq system with critical dissipationMar 22 2009In this paper we study a fractional diffusion Boussinesq model which couples the incompressible Euler equation for the velocity and a transport equation with fractional diffusion for the temperature. We prove global well-posedness results.
On the spectral distribution of the free Jacobi processApr 27 2012Jul 07 2012In this paper, we are interested in the free Jacobi process starting at the unit of the compressed probability space where it takes values and associated with the parameter values $\lambda=1, \theta =1/2$. Firstly, we derive a time-dependent recurrence ... More
Imperfect bifurcation for the quasi-geostrophic shallow-water equationsJan 06 2018We study analytical and numerical aspects of the bifurcation diagram of simply-connected rotating vortex patch equilibria for the quasi-geostrophic shallow-water (QGSW) equations. The QGSW equations are a generalisation of the Euler equations and contain ... More
Non uniform rotating vortices and periodic orbits for the two-dimensional Euler EquationsJul 26 2018Sep 12 2018This paper concerns the study of some special ordered structures in turbulent flows. In particular, a systematic and relevant methodology is proposed to construct non trivial and non radial rotating vortices with non necessarily uniform densities and ... More
The holographic Ricci dark energy and its possible doomsdaysJan 31 2013It is well known that the holographic Ricci dark energy can induce some future doomsdays in the evolution of the universe. Here we analyse the possible avoidance of those doomsdays by invoking a modification to general relativity on the form of curvature ... More
Lasers for coherent optical satellite links with large dynamicsMay 14 2013We present the experimental realization of a laser system for ground to satellite optical Doppler ranging at the atmospheric turbulence limit. Such a system needs to display good frequency stability (a few parts in 10^{-14}) whilst allowing large and ... More
Bottom Up Quotients and Residuals for Tree LanguagesJun 09 2015In this paper, we extend the notion of tree language quotients to bottom-up quotients. Instead of computing the residual of a tree language from top to bottom and producing a list of tree languages, we show how to compute a set of k-ary trees, where k ... More
Extended and localized Hopf-Turing mixed-mode in non-instantaneous Kerr cavitiesNov 13 2016We investigate the spatio-temporal dynamics of a ring cavity filled with a non-instantaneous Kerr medium and driven by a coherent injected beam. We show the existence of a stable mixed-mode solution that can be either extended or localized in space. The ... More
On the Query Complexity of Black-Peg AB-MastermindNov 17 2016Mastermind game is a two players zero sum game of imperfect information. The first player, called codemaker, chooses a secret code and the second player, called codebreaker, tries to break the secret code by making as few guesses as possible, exploiting ... More
The holographic induced gravity model with a Ricci dark energy: smoothing the little rip and big rip through Gauss-Bonnet effects?Dec 26 2011Mar 09 2012We present an holographic brane-world model of the Dvali-Gabadadze-Porrati (DGP) scenario with and without a Gauss-Bonnet term (GB) in the bulk. We show that an holographic dark energy component with the Ricci scale as the infra-red cutoff can describe ... More
An analytical and numerical study of steady patches in the discOct 06 2015In this paper, we prove the existence of $m$-fold rotating patches for the Euler equations in the disc, for both simply-connected and doubly-connected cases. Compared to the planar case, the rigid boundary introduces rich dynamics for the lowest symmetries ... More
Block thresholding for wavelet-based estimation of function derivatives from a heteroscedastic multichannel convolution modelFeb 28 2012Mar 13 2013We observe $n$ heteroscedastic stochastic processes $\{Y_v(t)\}_{v}$, where for any $v\in\{1,\ldots,n\}$ and $t \in [0,1]$, $Y_v(t)$ is the convolution product of an unknown function $f$ and a known blurring function $g_v$ corrupted by Gaussian noise. ... More
Hamming distance geometry of a protein conformational space. Application to the clustering of a 4 ns molecular dynamics trajectory of the HIV-1 integrase catalytic coreOct 23 2001Protein structures can be encoded into binary sequences, these are used to define a Hamming distance in conformational space: the distance between two different molecular conformations is the number of different bits in their sequences. Each bit in the ... More
Doubly connected V-states for the generalized surface quasi-geostrophic equationsDec 15 2014Jun 30 2015In this paper, we prove the existence of doubly connected V-states for the generalized SQG equations with $\alpha\in ]0,1[.$ They can be described by countable branches bifurcating from the annulus at some explicit "eigenvalues" related to Bessel functions ... More
The Influence of Canyon Shadowing on Device-to-Device Connectivity in Urban ScenarioOct 08 2018In this work, we use percolation theory to study the feasibility of large-scale connectivity of relay-augmented device-to-device (D2D) networks in an urban scenario, featuring a haphazard system of streets and canyon shadowing allowing only for line-of-sight ... More
Doubly connected V-states for the planar Euler equationsSep 24 2014We prove existence of doubly connected V-states for the planar Euler equations which are not annuli. The proof proceeds by bifurcation from annuli at simple "eigenvalues". The bifurcated $V$-states we obtain enjoy a $m$-fold symmetry for some $m\ge 3.$ ... More
Adaboost with "Keypoint Presence Features" for Real-Time Vehicle Visual DetectionOct 07 2009We present promising results for real-time vehicle visual detection, obtained with adaBoost using new original ?keypoints presence features?. These weak-classifiers produce a boolean response based on presence or absence in the tested image of a ?keypoint? ... More
Optical phase locking of two infrared CW lasers separated by 100 THzMay 03 2014We report on phase-locking of two continuous wave infrared laser sources separated by 100 THz emitting around 1029 nm and 1544 nm respectively. Our approach uses three independent harmonic generation processes of the IR laser frequencies in periodically ... More
CW frequency doubling of 1029 nm radiation Using single pass bulk and waveguide PPLN crystalsMay 17 2013Following various works on second harmonic process using periodically poled Lithium Niobate crystals (PPLN), we report on the performances comparison between commercial bulk and waveguide crystals at 1029 nm. We use a continuous wave (CW) amplified Yb ... More
A coherent optical link through the turbulent atmosphereNov 23 2009Jan 28 2010We describe the realization of a 5 km free space coherent optical link through the turbulent atmosphere between a telescope and a ground target. We present the phase noise of the link, limited mainly by atmospheric turbulence and mechanical vibrations ... More
Percolation for D2D Networks on Street SystemsJan 31 2018We study fundamental characteristics for the connectivity of multi-hop D2D networks. Devices are randomly distributed on street systems and are able to communicate with each other whenever their separation is smaller than some connectivity threshold. ... More
Sensitivity of anomalous localized resonance phenomena with respect to dissipationJun 26 2014We analyze cloaking due to anomalous localized resonance in the quasistatic regime in the case when a general charge density distribution is brought near a slab superlens. If the charge density distribution is within a critical distance of the slab, then ... More
Frequency tripled 1542 nm telecom laser diode stabilized to iodine hyperfine line in the 10-15 rangeJul 01 2016We report on telecom laser frequency stabilization to narrow iodine hyperfine line in the green range of the optical domain, after a frequency tripling process using two nonlinear PPLN crystals. We have generated up to 300 mW optical power in the green ... More
Experimental study of radiative shocks at PALS facilityMar 13 2010We report on the investigation of strong radiative shocks generated with the high energy, sub-nanosecond iodine laser at PALS. These shock waves are characterized by a developed radiative precursor and their dynamics is analyzed over long time scales ... More
Quantum Decoherence of Single-Photon CountersMay 20 2011Sep 02 2011The interaction of a quantum system with the environment leads to the so-called quantum decoherence. Beyond its fundamental significance, the understanding and the possible control of this dynamics in various scenarios is a key element for mastering quantum ... More
Key technologies to accelerate the ICT Green evolution -- An operator's point of viewMar 22 2019The exponential growth in networks' traffic accompanied by the multiplication of new services like those promised by the 5G led to a huge increase in the infrastructures' energy consumption. All over the world, many telecom operators are facing the problem ... More