This paper focuses on the problem of multiplicative noise removal. We draw our inspiration from the modeling of speckle noise. By using a MAP estimator, we can derive a functional whose minimizer corresponds to the denoised image we want to recover. Although the functional is not convex, we prove the existence of a minimizer and we show the capability of our model on some numerical examples. We...

This paper studies three deregistration strategies (explicit, implicit, and timeout (TO) deregistration) for personal communication service (PCS) networks to determine the network conditions under which each strategy gives the best performance. Two performance measures are considered: 1) the probability that a portable cannot register (and receive service) and 2) the number of deregistration me...

The aim of the present article is to exhibit a method to embed the fourth power moment of the Riemann zeta-function Z 2 (g) = ∞ −∞ ζ 1 2 + it 4 g(t)dt into the structure of L 2 (Γ \G), with Γ = PSL 2 (Z) and G = PSL 2 (R). It is shown that there exists a Γ-automorphic function on G, whose value at the unit element is closely related to Z 2 (g), and whose spectral decomposition in L 2 (Γ \G) giv...

Let v be a valuation of the quotient field of a noetherian local domain R. Assume that v is centered at R. This paper studies the structure of the value semigroup of v, S. Ideals defining toric varieties can be defined from the graded algebra K[T ] of cancellative commutative finitely generated semigroups such that T ∩ (−T ) = {0}. The value semigroup of a valuation S need not be finitely gener...

In the present paper we construct differential invariants for generic rank 2 vector distributions on n-dimensional manifold. In the case n = 5 (the first case containing functional parameters) E. Cartan found in 1910 the covariant fourth-order tensor invariant for such distributions, using his ”reduction-prolongation” procedure (see [12]). After Cartan’s work the following questions remained op...

A method is presented to easily derive von Neumann stability conditions for a wide variety of time discretization schemes for the convection-di usion equation. Spatial discretization is by the -scheme or the fourth order central scheme. The use of the method is illustrated by application to multistep, Runge-Kutta and implicit-explicit methods, such as are in current use for ow computations, and...

Equivalences between conformal foliations on Euclidean 3-space, Hermitian structures on Euclidean 4-space, shear-free ray congruences on Minkowski 4-space, and holomorphic foliations on complex 4-space are explained geometrically and twistorially; these are used to show that 1) any real-analytic complex-valued harmonic morphism without critical points defined on an open subset of Minkowski spac...

We present and analyze a linearly implicit finite-difference scheme for computing approximate solutions and interface curves for the porous medium equation in one space variable. Our scheme requires only that linear, tridiagonal systems of equations be solved at each time step. We derive error bounds for the approximate interface curves as well as for the approximate solutions under the rather ...

A new logic of belief (in the “Only knowing” family) with confidence levels is presented. The logic allows a natural distinction between explicit and implicit belief representations, where the explicit form directly expresses its models. The explicit form can be found by applying a set of equivalence preserving rewriting rules to the implicit form. The rewriting process is performed entirely wi...

In this paper, we introduce the concept of constant time updateability for the functional operations that can be used for constructing functions. We believe that constant time updateability will be important in the future for guaranteeing interactive modeling of implicit surfaces that are defined by functional construction of functions. We have developed several tests to determine if a function...