The Experts below are selected from a list of 29409 Experts worldwide ranked by ideXlab platform
Quo Canh Ngo - One of the best experts on this subject based on the ideXlab platform.
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existence results for the einstein scalar field lichnerowicz Equations on compact riemannian manifolds
Advances in Mathematics, 2012Co-Authors: Quo Canh NgoAbstract:Abstract This article mainly concerns with the non-existence, existence, and multiplicity results for positive solutions to the Einstein-scalar field Lichnerowicz Equation on closed manifolds with a negative conformal-scalar field invariant. This Equation arises from the Hamiltonian Constraint Equation for the Einstein-scalar field system in general relativity. Our analysis introduces variational techniques to the analysis of the Hamiltonian Constraint Equation, especially those cases when the prescribed scalar curvature-scalar field function may change sign. To our knowledge, such a problem remains open.
Sunday A Reju - One of the best experts on this subject based on the ideXlab platform.
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penalty cost for one dimensional energized wave Equation
2007Co-Authors: Victor O Waziri, Sunday A RejuAbstract:This paper constructs the penalty cost functional for optimizing the onedimensional energized wave control operator. In some multiplier methods such as the Lagrange multipliers and Conjugate Gradient Method (CGM), the cost of augmenting the dynamical Constraint Equation into an unConstraint formulation involving an integral objective functional is guessed. The Extended Conjugate Gradient Method (ECGM) demands that the penalty cost functional be determined by computational procedure. The functional is completely given in terms space x and time dependent variable t.
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the penalty cost functional for the two dimensional energized wave Equation
2006Co-Authors: Victor O Waziri, Sunday A RejuAbstract:This paper constructs the penalty cost functional for optimizing the two-dimensional control operator of the energized wave Equation. In some multiplier methods such as the Lagrange multipliers and Pontrygean maximum principle, the cost of merging the Constraint Equation to the integral quadratic objective functional to obtain an unConstraint Equation is normally guessed or obtained from the first partial derivatives of the unconstrained Equation. The Extended Conjugate Gradient Method (ECGM) necessitates that the penalty cost be sequentially obtained algebraically. The ECGM problem contains a functional which is completely given in terms of state and time spatial dependent variables.
Romain Gicquaud - One of the best experts on this subject based on the ideXlab platform.
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A large class of non constant mean curvature solutions of the Einstein Constraint Equations on an asymptotically hyperbolic manifold
Communications in Mathematical Physics, 2012Co-Authors: Romain Gicquaud, Anna SakovichAbstract:We construct solutions of the Constraint Equation with non constant mean curvature on an asymptotically hyperbolic manifold by the conformal method. Our approach consists in decreasing a certain exponent appearing in the Equations, constructing solutions of these sub-critical Equations and then in letting the exponent tend to its true value. We prove that the solutions of the sub-critical Equations remain bounded which yields solutions of the Constraint Equation unless a certain limit Equation admits a non-trivial solution. Finally, we give conditions which ensure that the limit Equation admits no non-trivial solution.
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a limit Equation associated to the solvability of the vacuum einstein Constraint Equations using the conformal method
arXiv: General Relativity and Quantum Cosmology, 2010Co-Authors: Mattias Dahl, Romain Gicquaud, Emmanuel HumbertAbstract:Let $(M,g)$ be a compact Riemannian manifold on which a trace-free and divergence-free $\sigma \in W^{1,p}$ and a positive function $\tau \in W^{1,p}$, $p > n$, are fixed. In this paper, we study the vacuum Einstein Constraint Equations using the well known conformal method with data $\sigma$ and $\tau$. We show that if no solution exists then there is a non-trivial solution of another non-linear limit Equation on $1$-forms. This last Equation can be shown to be without solutions no solution in many situations. As a corollary, we get existence of solutions of the vacuum Einstein Constraint Equation under explicit assumptions which in particular hold on a dense set of metrics $g$ for the $C^0$-topology.
Seongdae Kim - One of the best experts on this subject based on the ideXlab platform.
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the effect of spatial filtering on accuracy of motion Constraint Equation
Signal Processing, 1993Co-Authors: Junghee Lee, Seongdae KimAbstract:Abstract The motion Constraint Equation has been widely investigated to find optical flow, but little attention has been paid to accuracy and reliability of the Constraint Equation. In this paper, the bound on accuracy of the Constraint Equation is derived and the effect of spatial filtering on the bound is examined.
Hanshellmut Nagel - One of the best experts on this subject based on the ideXlab platform.
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optical flow estimation and the interaction between measurement errors at adjacent pixel positions
International Journal of Computer Vision, 1995Co-Authors: Hanshellmut NagelAbstract:In order to estimate both components of optical flow as well as their first spatio-temporal derivatives, it is postulated that the Optical Flow Constraint Equation (OFCE) is valid in a spatio-temporal neighborhood of pixels. So far, it has been tacitly assumed that the partial derivatives of the gray value distribution—which are required for this approach at the pixel positions involved—are independent from each other. It is shown how dropping this assumption affects the estimation procedure, based on well established approaches of estimation theory. The insight gained thereby is used to develop an approach towards merging image regions based on the compatibility of optical flow estimates obtained within the regions considered for merger.