The polar regions of the solar corona exhibit during solar minima very faint ray-like structures which apparently outline the lines of polar magnetic field. Usually they are named plumes in the solar coronal literature. In order to understand the spatiotemporal characteristics of these plumes we analyze a sequence of 400 continuous observations covering a period of 3 days. For such analysis we ...

This paper applies a sensor which has been developed based on a model of primate vision to corner fixation. Fixation is critical for the log-polar sensor as many of the sensor’s advantages are demonstrated only under fixation. This paper presents a fast corner fixation algorithm using the log-Hough transform to find the dominant centre-most corner and aligning the optical axis with the corner. ...

A type of conductive graphite/cellulose composite film used for chemical vapor-sensing material was prepared at room temperature in the ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIm]Cl). Graphite was pretreated with both oxidation and reduction processes. Due to the use of N,N-carbonyldiimidazole (CDI), as a covalent cross-linking agent in [BMIm]Cl, there were limited chemical bonds ...

| The 3D Radon transform of an object is an important intermediate result in many analytically exact cone-beam reconstruction algorithms. In this paper, we present a new, highly eecient method for 3D Radon inversion, i.e. reconstruction of the image from the 3D Radon transform, called Direct Fourier Inversion (DFI). The method is based directly on the 3D Fourier Slice Theorem. From the 3D Radon...

This paper presents a non-binary polar coding scheme that can reach the equidistant distant spectrum bound for discrete memoryless channels. This is the best that can be reached up to now and is tight for additive white Gaussian channels. To do this, we first define the equidistant property for the polarizing transforms. We have designed transforms that have better distance characteristics usin...

We develop fast discrete Fourier transforms (and their adjoints) from a square in space to a disk in the Fourier domain. Since our new transforms are not unitary, we develop a fast inversion algorithm and derive corresponding estimates that allow us to avoid iterative methods typically used for inversion. We consider the eigenfunctions of the corresponding band-limiting and space-limiting opera...

In this paper, we study the result of applying a lowpass variant filtering using scaling-rotating kernels to both the spatial and spatial-frequency representations of a two-dimensional (2-D) signal (image). It is shown that if we apply this transformation to a Fourier pair, the two resulting signals can also form a Fourier pair when the filters used in each domain maintain a dual relationship. ...

In this paper, we first give a characterization of sub-topical functions with respect to their lower level sets and epigraph. Next, by using two different classes of elementary functions, we present a characterization of sub-topical functions with respect to their polar functions, and investigate the relation between polar functions and support sets of this class of functions. Finally, we obtai...

Polar code is a recent forward error correction technique that characterized by its low encoding/decoding complexity and good performance. In this paper, complete image transmission system (transmitter receiver) proposed to improve the quality over different types of channels such as Gaussian, Rayleigh Rician channels. The based on encoding most significant quantized Discrete Cosine Transform (...