Multi-scale MAP despeckling of sonar images

Abstract

The SONAR images are perturbed by a multiplicative noise calIed speckle, due to the coherent nature of the scattering phenomenon. The use of speckle reduction filters is necessary to optimize the images exploitation procedures. This paper presents a new speckle reduction method in the waveiets domain using a novel Bayesian-based algorithm, which tends to reduce the speckle, preserving the structural features (like the discontinuities) and textural information of the scene. A blind specklesuppression method tbat performs a nonlinear operation on the data, based on B new bishrink filter variant is obtained. Finally, some simulation examples prove the performances of the proposed denoising method. These performances are compared with the results obtained applying state-of-the-art speckle reduction techniques.

A wavefunction description of quantum Fokker–Planck dissipation: derivation and numerical approximation of transient dynamics

“…We recall that the D pp -term, one of the sources of decoherence [21], does not contribute to the final form of equation (7). This is due to the fact that the moment system associated with the WFPE has been truncated at the level of the momentum equation, while the D pp -contribution is only 'visible' at the next level, i.e.…”

Quantum-to-classical transition and entanglement sudden death in Gaussian states under local-heat-bath dynamics

“…The linearity of the evolution map ensures that any density matrix ρ(0) = P (λ,λ * ,0)|λ λ|d 2 λ will evolve to ρ(t) = P (α,α * ,t)|α α|d 2 …”

“…Unfortunately, quantum systems are inherently fragile and extremely sensitive to environmental interactions. It is a common belief that the evolution of a quantum system in contact with a dissipative environment results in an asymptotic transition to classicality [2][3][4] and thus an inevitable loss of entanglement, since classicality subsumes disentanglement. Recently however it has been shown [5][6][7] that there exists a certain class of two-qubit states which display a finite entanglement decay time.…”