 Abstract—Discrete trigonometric transformations, such as the discrete Fourier and cosine/sine transforms, are important in a variety of applications due to their useful properties. For example, one well-known property is the convolution theorem for Fourier transform. In this letter, we derive a discrete Fresnel transform (DFnT) from the infinitely periodic optical gratings, as a linear trigon...

We studied coupling phenomena between surface plasmons and electromagnetic waves in the microwave spectrum using circular apertures surrounded by array of grooves.We first present experimental and theoretical results of enhanced microwave transmission though a subwavelength circular aperture with concentric periodic grooves around the surface plasmon resonance frequency. This is followed by tra...

A non-abelian finite group is called sequenceable if for some positive integer , is -generated ( ) and there exist integers such that every element of is a term of the -step generalized Fibonacci sequence , , , . A remarkable application of this definition may be find on the study of random covers in the cryptography. The 2-step generalized sequences for the dihedral groups studi...

A numerical study is carried out to investigate the laminar forced convection heat transfer from a circular cylinder. The fluid is assumed to be incompressible, the Reynolds number ranged from 0.1 to 1000, and the Prandtl number was equal to 0.7. The range of study includes heat transfer in creeping flow (Re40). The equations were discretized by a control-volume-based finite difference techniqu...

It has been previously shown that a radially periodic image having a symmetric radial period can be decomposed into a circular Fourier series of circular cosine functions with radial frequencies of f = 1/T , 2/T , . . . , and that its Fourier spectrum consists of a series of half-order derivative impulse rings with radii f = n/T (which are the Fourier transforms of the circular cosines in the s...