Indexing terms: Coding, Image processing, Fractal transforms In this letter the contractivity of existing fractal transforms for use in image compression schemes is examined. The coding process is described as nonlinear transformation in the finite dimensional euclidean vector space. We derive sufficient conditions for contractivity based on the spectral norm and the spectral radius of the tran...

We use dispersive Fourier transformation to measure shot-to-shot spectral instabilities in femtosecond supercontinuum generation. We study both the onset phase of supercontinuum generation with distinct dispersive wave generation, as well as a highly-unstable supercontinuum regime spanning an octave in bandwidth. Wavelength correlation maps allow interactions between separated spectral componen...

I apply Fourier and Chebyshev spectral methods to derive accurate and efficient algorithms for velocity continuation. As expected, the accuracy of the spectral methods is noticeably superior to that of the finite-difference approach. Both methods apply a transformation of the time axis to squared time. The Chebyshev method is slightly less efficient than the Fourier method, but has less problem...

We consider non-vanishing boundary conditions (NVBC) for the NLS model [1, 2, 3] in the context of the hybrid dressing transformation and τ -function approach. In order to write the NLS model in a suitable form to deal with non-vanishing boundary conditions it is introduced a new spectral parameter in such a way that the usual NLS parameter will depend on the affine parameter through the so-cal...

Land use change may influence many natural phenomena and ecological processes, including runoff, soil erosion, sedimentation and soil conditions. Decreasing of forest area in the North of Iran is one of the critical problems in recent years. The aims of this study are to detect land use changes between 1967 to 2002 using satellite images of Land Sat 7 ETM+ (2002), aerial photos and digital topo...

Abstract We study a Miura-type transformation between Kac - van Moerbeke (Volterra) and Toda lattices in terms of the inverse spectral problem for Jacobi operators, which appear Lax representation such systems. This method, amounts to reconstruction operator from moments its Weyl function, can be used solving initial-boundary value both It is shown that Miura easily described these moments. Usi...

Advances in remote sensing technology can help estimate biodiversity at large spatial extents. To assess whether we could use hyperspectral visible near-infrared (VNIR) spectra to estimate species diversity, we examined the correlations between species diversity and spectral diversity in early-successional abandoned agricultural fields in the Ridge and Valley ecoregion of north-central Virginia...

In this paper the high-order accurate spectral difference method for the Navier-Stokes equations is applied to moving boundary problems. Boundary movements are achieved, firstly, through rigid displacement of the entire flow domain. In order to account for the dynamic rigid mesh motion, the Navier-Stokes equations are modified through an unsteady coordinate transformation. Airfoils in pitching ...