During the long main phase of St Patrick’s Day storm on March 17, 2015, we found three separate enhancements westward electrojet. These are observed in ionospheric equivalent currents computed using geomagnetic data over Fennoscandia. Using from IMAGE magnetometer network, identified localised field-aligned current (FAC) systems superimposed pre-existing system. We suggest that these wedgelets ...

We study a simple “Horizon Model” for the problem of recovering an image from noisy data; in this model the image has an edge with α-Hölder regularity. Adopting the viewpoint of computational harmonic analysis, we develop an overcomplete collection of atoms called wedgelets, dyadically organized indicator functions with a variety of locations, scales, and orientations. The wedgelet representati...

Recently, Field, Lewicki, Olshausen, and Sejnowski have reported efforts to identify the “Sparse Components” of image data. Their empirical findings indicate that such components have elongated shapes and assume a wide range of positions, orientations, and scales. To date, Sparse Components Analysis (SCA) has only been conducted on databases of small (e.g. 16-by-16) image patches and there seem...

Signal processing plays a pivotal role in information gathering and decision making. This paper presents and compares different signal processing techniques used in marine and navy applications, primarily based on using wavelets as kernel. The article covers Fourier transform, time frequency wavelet based techniques such as bandelets, contourlets, curvelets, edgelets, wedgelets, shapelets, and ...

This paper presents the estimation methods of subtle hypodense changes of brain tissue in noncontrast CT scans. The purpose of reported research is improved detection of direct signs of hyperacute ischemic stroke. Proposed tool is nonlinear approximation in base of multiscale functions with respective thresholding. Different rationales for best basis selection were considered. Several local bas...

We introduce graph wedgelets - a tool for data compression on graphs based the representation of signals by piecewise constant functions adaptively generated binary partitionings. The adaptivity partitionings, key ingredient to obtain sparse representations signal, is realized in terms recursive wedge splits adapted signal. For this, we transfer adaptive partitioning and techniques known 2D ima...

Multiresolution triangulation meshes are widely used in computer graphics for 3-d modeling of shapes. We propose an image representation and processing framework using a multiscale triangulation of the grayscale function. Triangles have the potential of approximating edges better than the blocky structures of tensorproduct wavelets. Among the many possible triangulation schemes, normal meshes a...